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CatalogⅠIntroductionⅡ Brief introduction of a CapacitorⅢ What is Parallel Plate Capacitor ?Ⅳ The Working Principle and Application of Parallel Plate Capacitor4.1 Construction & Principle4.2 The Application of Parallel Plate CapacitorⅤ Parallel Plate Capacitor Formula5.1 The formula5.2 How to Derivate Parallel Plate CapacitorⅥ Solved Examples6.1 Exemplification 16.2 Exemplification 2Ⅶ Frequently Questions about Parallel Plate Capacitor ⅠIntroductionWe are so reliant on mobile applications and devices for entertainment and work in the digital electronic platform. Laptops and mobile phones have rechargeable batteries to make them more convenient. These batteries are subject to the charging and discharging phenomena. When these are charged, they become mobile. Capacitors are used in all rechargeable circuits. These capacitors are filled with various dielectrics, resulting in various capacitor types. Paper capacitors, for example, mica capacitors, and so on. Similarly, a parallel plate capacitor is a type of capacitor that can increase capacitance. These are the most common energy-storing elements.  Ⅱ Brief introduction of a CapacitorThe capacitor, a component, like a small rechargeable battery, has the ability or "capacity" to store energy in the form of an electrical charge that produces a potential difference (Static Voltage) across its plates.Capacitors contain various sizes and shapes, ranging from very small capacitor beads used in resonance circuits to large power factor correction capacitors, but they all do the same thing: they store charge.A capacitor, in its most basic form, is made up of two or more parallel conductive (metal) plates that are not connected or touching each other, but are electrically separated by air or some form of good insulating material such as waxed paper, mica, ceramic, plastic, or some form of a liquid gel as used in electrolytic capacitors. The Dielectric is the insulating layer that exists between the plates of a capacitor. Ⅲ What is Parallel Plate Capacitor ? A parallel plate capacitor consists of two parallel metal conductor plates that are separated in the middle by a dielectric material. There will be an electrostatic field distribution between the two plates when there is a certain potential difference between them. The area between the two plates has a uniform electric field distribution. The electric field lines at the capacitor's edge are curved and divergent due to the edge effect. The parallel plate capacitor is the most basic type of capacitor. Any non-parallel plate capacitor can be thought of as a series and parallel connection of a number of small parallel plate capacitors.A parallel plate capacitor is an arrangement of two plates that are parallel to each other and separated by a dielectric material. These plates perform the function of electrodes. Figure1: basics of a parallel plate capacitor Ⅳ The Working Principle and Application of Parallel Plate Capacitor This section will be divided into two parts. The first section introduces construction steps. Another section will demonstrate how a parallel plate capacitor works. 4.1 Construction & Principle The parallel plate capacitor can be built by following the steps outlined below：The plates used to build the parallel plate capacitor must have the same dimensions.The power supply for these plates has to be provided.Positive charges are necessary for a plate to connect the positive side of the battery.Similarly, the plate connected to the supply's negative terminal is charged with negative charges.As a result, an electric field is formed between those plates.As a result, an electric field is formed between those plates. Figure2: the construction of parallel plate capacitor The parallel plate capacitor operates on the following principle:• A plate in the capacitor is charged to a specific value.• As the number of charges applied to the plate increases, so does the potential.• The charges may leak due to the increase in potential.• To overcome such a situation, another plate is placed next to the first positively charged plate.• The negative charges are transferred to the next plate that is placed.• Both plates are now charged.• Because of the presence of negative charges on the second plate, the potential difference on the first plate tends to be reduced.• Similarly, the presence of positive charges on the opposite side of the second plate tends to increase the potential difference on the first plate.• However, the effect of potential difference due to negative charges on the second plate is significant. As a result, the first plate receives a greater number of charges. Figure3: the principle of parallel plate capacitor 4.2 The Application of Parallel Plate CapacitorCapacitors, in addition to storing electricity, play an important role in electricians and electronic circuits. Capacitors are used in the control of current and voltage in an alternating current circuit, the generation of oscillating current in a transmitter, tuning in a receiver, filtering in a rectifier circuit, time delay in an electronic circuit, and so on.Parallel plate capacitors operate in the following applications:• This type of capacitor works in batteries (Rechargeable Energy System).• Such capacitors are applied to dynamic digital memory systems.• Such capacitors are used in radars and Pulsed LASER circuits.• Parallel plate capacitors are used in signal suppression or signal coupling. Ⅴ Parallel Plate Capacitor FormulaThe electric field's direction is defined as the direction in which the positive test charge would flow. Capacitance is the body's inability to store an electric charge. Each capacitor has its own capacitance. A typical parallel-plate capacitor is made up of two metallic plates of area A separated by d. 5.1 The formulaThe parallel plate capacitor formula is given byC=kϵ0AdWhere,ϵo is the permittivity of space (8.854 × 10−12 F/m)k is the relative permittivity of dielectric material Figure4:Parallel Plate Capacitor Formula 5.2 How to Derivate Parallel Plate Capacitor A parallel plate capacitor is depicted in the diagram below. Two large plates are parallel to each other and separated by a small distance d. As shown by the dotted array, the space between the plates is filled with a dielectric medium. The two plates are charged in opposite directions. Figure5:Two plates We can see that the first plate has a charge +Q and the second plate has a charge –Q. Each plate's area is A, and the distance between these two plates is d. The distance d is much smaller than the area of the plates, and we can write dA, so the effect of the plates is treated as that of an infinite plane sheet with uniform surface charge density, and the electric field generated by them is treated as that of an infinite plane sheet with uniform surface charge density. Because the total charge on plate 1 is Q and the plate area is A, the surface charge density can be calculated as ：Similarly, for plate 2 with a total charge of –Q and area A, the surface charge density can be calculated as follows:The regions surrounding the parallel plate capacitor are divided into three sections, with area 1 being the area to the left of the first plate, area 2 being the area between the two planes, and area 3 being the area to the right of plate 2.Let's compute the electric field in the vicinity of a parallel plate capacitor.Region I: The magnitude of the electric field due to infinite plane sheets I and II is the same at any point in this region, but the direction is opposite. The two forces cancel each other out, and the overall electric field is given as,Region II: The magnitude and direction of the electric field due to plane sheets I and II in these regions are the same, and the overall effect is as follows:Region III: As in Region I, the magnitude of the electric field generated by plane sheets I and II is the same, but the direction is opposite, yielding the same result as,The electric field is uniform throughout and runs from the positive plate to the negative plate in this case. The potential difference across the capacitor can be calculated by multiplying the electric field by the distance between the planes, as shown in the equation.The following is the  capacitance  of parallel plate capacitor:  Ⅵ Solved Examples 6.1 Exemplification 1A parallel plate capacitor is kept in the air and has an area of 0.50m2 and a distance of 0.04m between them. Determine the parallel plate capacitor.Solution:Given:Area A = 0.50 m2,Distance d = 0.04 m,relative permittivity k = 1,ϵo = 8.854 × 10−12 F/mThe parallel plate capacitor formula is as follows:C=k0Ad = 8.8541092 0.50 / 0.044.427 x 1012 / 0.04As a result, C = 110.67 x 1012 F. 6.2 Exemplification 2If the capacitance is 25 nF and the separation between the plates is 0.04m, calculate the area of a parallel plate capacitor in the air.Solution:Given:Capacitance is equal to 25 nF.d = 0.04 m distancek = relative permittivity8.854 1012 F/m = o The parallel plate capacitor formula is as follows:C=k0Ad A=dCk0 = 0.04 25109 / 18.5541012A = 1 x109/ 8.854 1012As a result, the area of the parallel plate capacitor is 112.94 m2. Ⅶ Frequently Questions about Parallel Plate Capacitor1. What happens to the charge on A parallel plate capacitor?What happens to the charge on a parallel-plate capacitor if the potential difference doubles? The charge on each plate doubles. You want to increase the maximum potential difference of a parallel-plate capacitor. Describe how you can do this for a fixed plate separation. 2. When a battery is connected to a capacitor Why do the two plates?Explanation: In any circuit, electrons are neither created nor destroyed according to the laws of conservation of charge, but are transferred from one point to another on the circuit. When the plates of a capacitor are connected to battery, the battery pushes the electron to move due to its potential difference. 3. How do you find the charge on each plate of a capacitor?The amount of charge that moves into the plates depends upon the capacitance and the applied voltage according to the formula Q=CV, where Q is the charge in Coulombs, C is the capacitance in Farads, and V is the potential difference between the plates in volts. 4. How can we increase the capacitance of a parallel plate capacitor?Hence the capacitance can be increased by either increasing the plate area or decreasing the spacing between plates. Hence, by decreasing the plate separation, the capacitance of a parallel-plate capacitor can be increased. Thus, option (E) is the correct answer. 5. How many types are there for increasing the capacitance of parallel plate capacitor?If you want to increase the Capacitance of Parallele Plate Capacitor then increase the surface area, reduce the separation between the plate and use a dielectric material in between the plate which have higher dielectric breakdown strength.

Ⅰ IntroductionOne of those imperative passive electrical components that are present in a large range of circuits is capacitors. If you are a DIY enthusiast who is enthusiastic about electronic circuits, it is a must to understand the condenser types to use them correctly in suitable circuits. We help you decode and understand the uses of one of the most common types of capacitors are called the film capacitors here in this article. The fundamentals of capacitors, their forms and when to use them, have already been discussed. Notice that Film Capacitors are known by several names, Polyester Capacitors and Mylar Capacitor are some common ones, all of them, in general, are covered in this article. Capacitors can generally be divided into two broad categories: polarized and nonpolarized. Due to its flexibility and low cost, the film capacitor is a form of non-polarized capacitor and is very common. Read on to learn more about a film condenser: what a film condenser is, how it is made, and what makes it so famous. Let's start with this little passive gadget with a brief introduction.CatalogⅠ IntroductionⅡ Definition of Film CapacitorsⅢ A Variety of CapacitorsⅣ Brief History of Film CapacitorsⅤ Types of Film Capacitors and Their Applications  5.1 Film/Foil Capacitors  5.2 Metalized Film CapacitorsⅥ Features and Applications of Film CapacitorsⅦ How is Film Capacitor different from Electrolytic Capacitor and Ceramic Capacitor?Ⅷ Construction of Film CapacitorⅨ FAQⅡ Definition of Film CapacitorsThe film capacitor is a non-polarized capacitor and thin plastic films are used to produce its dielectric. These plastic films are often metalized and are available under the name of 'metalized condenser' on the market. Such capacitors are also often referred to as plastic capacitors or metalized capacitors. A Thin Film Capacitor is nothing but a plastic film with bipolar capacitors as their dielectric. To form a roll or a candy-like rectangular shape, these films are either metalized or just put in layers. Polypropylene(PP) /Polyethylene terephthalate (PET)/ Polytetrafluoroethylene(PTFE)/Polyphenylene Sulfide (PET) are the dielectrics widely used (PPS) The primary benefit of using a film capacitor is that it has a very low distortion factor and excellent frequency features. The wide variety of plastic film used for various film condensers makes them flexible. These capacitors often do not wear off easily and are ideal for applications such as coupling/decoupling circuits, ADC, audio circuits, and many more for high voltage and high-frequency applications. Bypass and decoupling capacitors, which are popular applications for condensers, have also been addressed previously.Ⅲ A Variety of CapacitorsWe need to understand the context behind the common words Film Capacitor, Polyester Capacitor, Mylar Capacitor, and Polypropylene Capacitor before we continue with our post. There are several types of film capacitors depending on the type of dielectric plastic material used in the capacitor, one of which is the most widely used polyester condenser and polypropylene condenser. Often known as Polyester Film Capacitors, the polyester capacitor has a dielectric material made of a polymer named polyethylene terephthalate (PET). This is why often this capacitor is referred to as the PET Film Capacitor. There are several Polyester Capacitor manufacturers, of which Hostaphan is the leading one. The Polyester Capacitor is also often called a Mylar Capacitor to address the vendor term. Below, a typical Mylar capacitor is shown.Another type of film capacitor in which the dielectric material is made of polymer caller polypropylene (PP), is the polypropylene film capacitor, hence the name Polypropylene Film Capacitor or PP Film Capacitor. Below is a typical polypropylene capacitor.Similarly, depending on the type of polymer used for the dielectric, there are more than 10 different types of film capacitors, the properties of which vary slightly, but the overall functionality and application almost remain the same. We will get into the specifics later, but let's dive into history before that.Ⅳ Brief History of Film CapacitorsPaper capacitors were used in the decoupling circuits before film capacitors came into the picture. Impregnated paper that was placed with metal strips and rolled into cylindrical forms was used by paper condensers. Since these capacitors had paper as a dielectric, however, they were not only likely to be vulnerable to environmental defects and were very voluminous in size. Scientists have therefore started to look for a solution that would mitigate these problems. It was at a time when the plastic industry was booming and scientists discovered how long-term stability in terms of its electrical parameters was given by the use of complex plastic films as a dielectric. As multilayers of paper were replaced by only a few sheets of plastic, it also helped to reduce the bulk. As technology progressed, thinner plastics with high reliability decreased the size of these capacitors.Ⅴ Types of Film Capacitors and Their ApplicationsThe plastic industry saw growth in the production of thinner and more robust goods soon after the first film capacitor was introduced. Different kinds of plastic film capacitors have been used as a dielectric to accommodate various circuit applications over the years. There are several film condensers in which the plastic films are actually put between the aluminum foils and there are others in which the plastic film is metalized by a phase in which the metal is coated on the film itself. In general, based on construction, film capacitors can be divided narrowly into two groups. Notice that only the construction is based on the classification.5.1 Film/Foil CapacitorsThe film/foil capacitor, as the name implies, uses plastic films as a dielectric and is mounted within two layers of aluminum foil electrodes. These interleaved layers are so organized that they do not touch each other with the metallic layers. Such capacitors can be either non-inductive or inductive.In such a way that the aluminum foils are located in the middle of the two films, an inductive film foil capacitor is wound. The aluminum foils are not directly attached but through a leading wire that carries the entire winding. A pictorial representation of it is shown in Figure 1.In a non-inductive fill foil capacitor, the aluminum foils are arranged in such a way that each foil is positioned to a certain degree out of the films, such as that shown in Figure 2.Plastic Film Capacitor Characteristics:• High insulation resistance• Good capacitance stability• High efficiency even at high frequency• Dielectric used: Polypropelene(PP)/ Polyethylene terephthalate (PET)/Polytetrafluoroethylene(PTFE)Plastic Film Capacitor ApplicationThe film/foil capacitor application depends on the type of dielectric used. For coupling, decoupling, and bypassing, PET Film/foil capacitors are great. PP Film/Foil (PP) capacitors are a good choice for use in circuits requiring high switching frequencies, such as resonant and oscillator circuits, power supplies, etc.5.2 Metalized Film CapacitorsThe primary distinction between a film foil capacitor and a metalized capacitor is that the metallic electrodes are fused into either side of the dielectric plastic in the latter instead of layering. While it raises the cost and also adds a step in the production process, it has greater reliability and smaller dimensions than in a film foil condenser. To get the desired capacitance value, the thickness of the plastic film can be as low as 0.6μm.Metalized Film Capacitor Characteristics:• Self-healing property: This property helps the capacitor to repair itself if the electrodes are exposed to each other instead of being short-circuited. This increases the capacitor reliability• Compact in dimension and form• Polypropylene(PP)/polyethylene terephthalate(PET)/ polytetrafluoroethylene(PTFE)/ polyphenylene sulfide Dielectric used: polypropylene(PP)/polyethylene terephthalate (PET) (PPS)Metalized Film Capacitor Application:In electronic control circuits, including DC link circuits, pulse circuits, switching circuits, etc., metallic film capacitors are commonly used.  In decoupling and filtering applications, the low power metalized film capacitor finds use.Ⅵ Features and Applications of Film CapacitorsThe film capacitors often provide other features, in addition to the normal use of condensers to accumulate electrical charges. In high-frequency circuits, their bipolar nature and exceptional frequency characteristics make them famous. The standard capacitance value for these capacitors, in general, ranges from 1nF to 30muF. These small passive parts can have a voltage level of as low as 50 V and as high as 2 kV, so they can be used in a wide variety of applications. One of the fascinating facts is that various types of plastic film are used by these film capacitors as a dielectric. In general, each type of film provides a condenser with different temperature and frequency characteristics. Therefore, one can select the best solution for their needs in their circuits with the correct choice of the dielectric. For example, the PP film capacitor would be the best choice if you are looking for a film capacitor to be mounted in a circuit intended for high-power/high-frequency applications, such as induction heaters, for example. A comparison of the frequency and temperature characteristics of 4 different plastic film dielectrics, namely PP, PPS, PEN, and PET, is shown in the figure below. The only difference is the dielectric material between these capacitors and you will note the shift in temperature and frequency is very obvious.Among other aspects, film capacitors are mainly known for their low dissipation factor, stable capacitance, and high insulation resistance, such as negative temperature and high-reliability characteristics. Hence, for a wide range of applications, they are common choices. These film capacitors generate optimum output from simple sample/hold circuits for ADCs, oscillatory circuits, timers, to finding a position in the coupling/decoupling units of high-end electronic power circuits. Over the past few decades, these capacitors have replaced the use of ceramic and electrolyte capacitors in many circuits in automotive and industrial applications. For some applications, let's compare the film capacitor with the other common capacitors and get to know what makes them a better option.Ⅶ How is Film Capacitor different from Electrolytic Capacitor and Ceramic Capacitor?The first difference between these three capacitors that is quite obvious is the type of dielectric used and their construction. While film capacitors use thin sheets of plastic film, ceramic capacitors, like the dielectric, use sheets made of ceramic material. In nature, both of them are bipolar. On the other hand, electrolytic capacitors have oxides that act as dielectrics and are polar. The differences in their production and dielectrics have an enormous impact on their results. As discussed above, a wide variety of capacitance values are available for plastic film/metalized film capacitors. Ceramic capacitors, on the other hand, are only ideal for circuits that have low requirements for capacitance. For specific applications such as analog signal processing and audio circuits, due to the low distortion factor they offer, film capacitors are preferred over ceramic capacitors. Ceramic capacitors also tend to have high nonlinearities at high capacitances that affect the performance of the circuits. Capacitors with high capacitance and a low cost are favored for applications such as coupling/decoupling circuits. Both electrolytic and film capacitors are also good choices to choose from. The ESR (Equivalent Series Resistance) and ESL (Equivalent Series Inductance) value of the capacitor is another major factor that is considered when designing such circuits. As already discussed, in contrast to electrolytic capacitors, film capacitors have a stronger ESR and ESL performance and a much lower distortion factor and are thus favored over aluminum electrolytic capacitors. Also, if the aging time between these three capacitors is compared, film capacitors appear to avoid the wearing out process between them for the longest time. For high voltage and high-frequency applications, this makes them a safer option.Ⅷ Construction of Film CapacitorThe generic method of development for these capacitors begins with the removal of a thin layer of plastic film. This film's thickness determines the capacitance value. Since the capacitance value increases with a decrease in the gap between the electrodes, the higher capacitance value is thus indicated by the lower film thickness. The standard capacitance value for these capacitors, in general, ranges from 1nF to 30muF. Once the film is removed according to the desired capacitance value and the breakdown voltage, either aluminum or zinc is metalized and rolled over to form a' mother roll.' The films are only interlaced between sheets of aluminum foil to form the roll in the case of a film/foil capacitor. A flow diagram of the different steps involved in producing a metalized film capacitor is shown in the figure below.This roll is then manipulated to accommodate the capacitor size and the desired electrical characteristics by several processes such as slitting, winding and flattening. The projecting electrodes are subjected to a metalizing process called 'Schoopage' until the capacitor obtains its desired shape and size. To create a protective coating on the electrodes, liquefied metals such as zinc, aluminum, or tin are used here. To burn away any existing defects on the electrode surface, the lateral ends of the winding are then sprayed with compressed air and then exposed to a voltage. Since the capacitors can be easily influenced by moisture, silicone oil, or some other insulating fluid is impregnated with the winding. Finally, this winding is prepared to be soldered to the capacitor's metallic terminals. The capacitor is subjected to a final round of protection coating until soldered, where its body is dipped into a protected coating or potted on the outer casing.Ⅸ FAQ1. What is a film capacitor?A film capacitor is a plastic capacitor that is used to construct the dielectric and aluminum or zinc is used to construct the electrodes of the capacitor. 2. Can film capacitors explode when overloaded (like electrolytic)?If the overvoltage is very large you can damage them, eventually burn them, as with any electronic component you abuse. But IMHO explosion of film capacitors is not very likely. The danger when dealing with liquid electrolytic capacitors is that the electrolyte is acid, and if they explode they can cause severe injuries, for instance in the eyes. When they are 'abused' with over-voltage or with high reverse voltage (they are polarized, remember…) the pressure inside increases and they eventually explode. To avoid the pressure increases too much, they have 'escape valves' in the same way as high-pressure kitchen boilers have. In the capacitors those escape valves are thin 'weakened spots' in the plastic cover or there are cross-shaped grooves in the aluminum.  3. What is a film capacitor used for?Film capacitors can also be used in a more conventional way as voltage smoothing capacitors, filters, audio crossovers. They can be used to store energy and release it in a high-current pulse when needed. High-current electrical pulses are used to power pulsed lasers or generate lightning discharges. 4. What is the preferred application of a film capacitor?For particular applications like analog signal processing and audio circuits, film capacitors are preferred over ceramic capacitors due to the low distortion factor which they offer. Also at high capacitances, ceramic capacitors tend to have high nonlinearities which affect the performance of the circuits. 5. How do you determine the polarity of a film capacitor?Based on the height of the capacitor leads we can identify which is negative polarity and which is positive polarity. Capacitor whose terminal is longer is a positive polarity terminal or an anode and the capacitor whose terminal is shorter is a negative polarity or cathode. 6. What is an electrolytic or film capacitor?While the active part of electrolytic capacitors, the so-called wound cell, consists of aluminum (anode and cathode foil), paper, and electrolyte, the film capacitor is made of metal-coated plastic film that builds its electrodes. 7. Can I replace the film capacitor with ceramic?Yes, they are interchangeable, but ceramic disc capacitors are considerably more nonlinear in their voltage and frequency response compared to film capacitors. Ceramic caps can also be microphonic. 8. How do you use a film capacitor?Most power capacitors, the largest capacitors made, generally use polypropylene film as the dielectric. PP film capacitors are used for high-frequency high-power applications such as induction heating, pulsed power energy discharge applications, and AC capacitors for electrical distribution. 9. How long do film capacitors last?The MKP1848 film capacitor has a life quoted as 100000 hrs at 70 degC. The life of a Rubycon BXC series wet electrolytic capacitor is quoted as 12000 hrs at 105degC. By way of the '10 degree rule', we can say that the lifetime of the Rubycon electrolytic capacitor at 70 degC would be 96000 hrs. 10. Do film capacitors degrade?The degradation of metalized film capacitors is a concern in applications exposed to high humidity environments. The metalized electrode layer in metalized film capacitors is very thin, typically less than 50 nm, which is susceptible to corrosion due to the ingress of atmospheric moisture.

IntroductionDefinition: A ceramic capacitor is a capacitor that has a ceramic dielectric as its dielectric material. Multi-layer ceramic capacitors and ceramic disc capacitors are the two most common types. The dielectric in a ceramic capacitor is ceramic. Ceramics, a well-known insulator, is one of the first materials used in the manufacture of capacitors. Ceramic capacitors come in a variety of geometric forms, some of which have been phased out due to size, parasitic effects, or electrical characteristics, such as ceramic tubular capacitors and barrier layer capacitors. Multi-layer ceramic capacitor, also known as ceramic multi-layer chip capacitor (MLCC), and ceramic disc capacitor are the two types of ceramic capacitors most widely used in modern electronics.                                                                                                                                             Typical Multilayer Ceramic Capacitor With a production volume of about 1000 billion devices per year, MLCCs are the most widely used capacitors. Due to their small size, they are commonly used and manufactured using SMD (surface-mounted) technology. Ceramic capacitors are usually made with very small capacitance levels, ranging from 1nF to 1F, with a maximum capacitance of 100F. Ceramic capacitors are thin, and their maximum rated voltage is low. Since they lack polarity, they can be safely linked to AC electricity. Due to low parasitic effects including resistance and inductance, ceramic capacitors have excellent frequency response. Ceramic capacitors have the following advantages over other capacitors: small size, large capacity, good heat resistance, mass production suitability, and low price.CatalogIntroductionCatalogⅠThe Origin of Ceramic CapacitorsⅡ Classification of Ceramic Capacitors  2.1 Semiconductor Ceramic Capacitors  2.2 High Voltage Ceramic CapacitorsⅢ Characteristics  3.1 Precision and Tolerance  3.2 Size Advantages  3.3 High Voltage and High PowerⅣ Ceramic Dielectric TypesⅤ Construction and Properties of Ceramic Capacitors  5.1 Ceramic Disc Capacitors  5.2 Multi-layer Ceramic Capacitor (MLCC) Ⅵ Advantages and Disadvantages  6.1 Advantages  6.2 DisadvantagesⅦ Applications for Ceramic CapacitorsⅧ How to read ceramic capacitor value?Ⅸ How to Test Ceramic Disc CapacitorⅩ FAQⅠThe Origin of Ceramic CapacitorsLombardi from Italy invented ceramic dielectric capacitors in 1900. It was discovered in the late 1930s that by adding titanate to ceramics, the dielectric constant can be doubled, resulting in cheaper ceramic dielectric capacitors. Ceramic capacitors were first used in military electronic equipment around 1940, following the discovery of the insulation properties of BaTiO3 (Barium titanate), the primary raw material for today's ceramic capacitors. Around 1960, ceramic laminate capacitors became commercially available. It had become an essential part of electronic devices by 1970, thanks to the rapid growth of hybrid IC, computers, and portable electronic devices. Ceramic dielectric capacitors currently account for approximately 70% of the overall capacitor market.                                                                                                             Historic Ceramic CapacitorsⅡ Classification of Ceramic Capacitors2.1 Semiconductor Ceramic Capacitors(1)Surface Layer Ceramic CapacitorThe miniaturization of capacitors, that is, the capacitor obtains the largest possible capacity in the smallest possible volume, which is one of the development trends of capacitors. For the separation of capacitor components, there are two basic approaches to miniaturization: ①Make the dielectric constant of the dielectric material as high as possible; ②Make the thickness of the dielectric layer as thin as possible. Among ceramic materials, the dielectric constant of ferroelectric ceramics is very high, but when ferroelectric ceramics are used to manufacture ordinary ferroelectric ceramic capacitors, it is difficult to make the ceramic dielectric very thin. Firstly, due to the low strength of ferroelectric ceramics, it is difficult to carry out actual production operations because it is easy to fracture when it is thin. Secondly, when the ceramic medium is fragile, it is easy to cause various structural defects and the production process will be challenging.(2)Grain Boundary Layer Ceramic CapacitorThe surface of BaTiO3 semiconductor ceramics with sufficiently developed grains is coated with appropriate metal oxides (such as CuO or Cu2O, MnO2, Bi2O3, Tl2O3, etc.), and heat treatment is performed under oxidizing conditions at appropriate temperatures. Then the substance will form a low eutectic solution phase with BaTiO3, rapidly diffuse and penetrate into the ceramic along with the open pores and grain boundaries, forming a thin solid solution insulating layer on the grain boundaries. The resistivity of this thin solid solution insulating layer is very high (up to 1012~1013Ω·cm). Although the ceramic grain interior remains as semiconductor, the entire ceramic body is shown as the dielectric constant of 2×104 to 8×104 dielectric medium. Capacitors made with this kind of porcelain are called boundary layer ceramic capacitors, or BL capacitors for short.2.2 High Voltage Ceramic CapacitorsThe ceramic materials of high-voltage ceramic capacitors are barium titanate-based and strontium titanate-based. Barium titanate-based ceramic materials have the advantages of high dielectric coefficient and good AC withstand voltage characteristics, but also have the shortcomings of capacitance change rate with the increase of medium-temperature and decrease of insulation resistance. The Curie temperature of strontium titanate crystal is -250℃, and it is a cubic perovskite structure at room temperature.  It is a para-electric body, and there is no spontaneous polarization phenomenon. Under high voltage, the dielectric coefficient of strontium titanate ceramic material changes little. The dielectric loss tangent value (tgδ) and capacitance change rate are small, which makes it a high-voltage capacitor dielectric. 2.3 Multilayer Ceramic CapacitorsMultilayer ceramic capacitors are the most widely used type of electronic component. They are stacked alternately in parallel with the internal electrode material and ceramic body and fired into a whole, also known as chip monolithic capacitors. It has the characteristic of small size, high specific volume and high precision. It can be mounted on a printed circuit board (PCB) and hybrid integrated circuit (HIC) substrates. It can effectively reduce the volume and weight of electronic information terminal products (especially portable products), and also improve product reliability.                                                             Multilayer ceramic capacitors conform to the IT industry's development direction of miniaturization, lightweight, high performance, and multifunction. The outline of the national vision goal for 2010 clearly puts forward that new components such as surface-mounted components should be the development focus of the electronic industry. It is not only simple packaging, good sealing, and can effectively isolate the opposite electrode. MLCC can store charge, block DC, filter merge, distinguish different frequencies and tune the circuit in the electronic circuit.  It can partially replace organic film capacitors and electrolytic capacitors in high-frequency switching power supplies, computer network power supplies and mobile communication equipment. What's more, it can greatly improve the filtering performance and anti-interference performance of high-frequency switching power supplies.                                                Ⅲ Characteristics3.1 Precision and ToleranceCeramic capacitors are currently available in two classes: class 1 and class 2. When high stability and low losses are needed, Class 1 ceramic capacitors are used. They are extremely precise, and the capacitance value remains constant regardless of applied voltage, temperature, or frequency. Within a total temperature range of -55 to +125 °C, the capacitance thermal stability of the NP0 series of capacitors is 0.54%. The nominal capacitance value's tolerances can be as poor as 1%. Class 2 capacitors have a large capacitance per volume and are used in less sensitive applications. Their thermal stability in the operating temperature range is usually 15%, and nominal value tolerances are about 20%.3.2 Size AdvantagesMLCC devices outclass other capacitors when high component packing densities are needed, as is the case in most modern printed circuit boards (PCBs). The “0402 multi-layer ceramic capacitor package” measures just 0.4 mm x 0.2 mm to demonstrate this point. There are 500 or more ceramic and metal layers in such a box. As of 2010, the minimum ceramic thickness was on the order of 0.5 microns.3.3 High Voltage and High PowerCeramic capacitors that are physically bigger and can withstand even higher voltages are known as power ceramic capacitors. These are much larger than the ones used on PCBs, and they have specialized terminals for connecting to a high-voltage supply safely. Ceramic capacitors with a power specification of much more than 200 volt-amperes can withstand voltages ranging from 2 kV to 100 kV. Printed circuit boards use smaller MLCCs that are rated for voltages ranging from a few volts to several hundreds of volts, depending on the application.Ⅳ Ceramic Dielectric TypesUnlike other capacitor types such as tantalum capacitors and electrolytic capacitors, ceramic capacitors may use a variety of dielectrics. These various dielectrics give capacitors very different properties, so in addition to deciding on a ceramic capacitor, a second decision about the type of dielectric may be needed. Popular ceramic capacitor dielectrics, such as C0G, NP0, X7R, Y5V, Z5U, and many others, are frequently listed in distributors' lists. However, determining which form is best necessitates a little more study. Ceramic Capacitor Dielectric ClassesSome industry organizations have identified a range of ceramic dielectric application classes to make selecting capacitors with the appropriate dielectric easier. These application groups divide the various ceramic capacitor dielectrics into separate classes based on the anticipated application.     International bodies such as the IEC (International Electrotechnical Commission) and the EIA (Electronic Industries Alliance) have standardized these ceramic capacitor classes.Ⅴ Construction and Properties of Ceramic Capacitors5.1 Ceramic Disc CapacitorsCeramic disc capacitors are made by coating a ceramic disc on both sides with silver contacts. These devices can be constructed from several layers to achieve higher capacitances. Ceramic disc capacitors are usually through-hole components that have lost popularity due to their large scale. If capacitance values allow, MLCCs are used instead. Ceramic disc capacitors have capacitance values ranging from 10pF to 100pF and voltage ratings ranging from 16 volts to 15 kV and beyond.                                                                    5.2 Multi-layer Ceramic Capacitor (MLCC)MLCCs are made by combining finely ground granules of paraelectric and ferroelectric materials and layering the mixture with metal contacts alternately. Following the layering, the device is heated to a high temperature and the mixture sintered, yielding a ceramic substance with the desired properties. The capacitance of the resulting capacitor is increased by connecting several smaller capacitors in parallel. MLCCs are made up of 500 layers or more, with a minimum layer thickness of 0.5 microns. As technology advances, layer thickness decreases, allowing for higher capacitances in the same volume.Ⅵ Advantages and Disadvantages6.1 AdvantagesThe following are some of the benefits of using a ceramic capacitor:• This capacitor's physical structure is very compact.• It is well suited for the application of AC signals due to its non-polarized nature.• Signal interference suppression, such as radiofrequency suppression and electromagnetic interference suppression, is improved with these capacitors.• This capacitor is reasonably priced, and it can withstand voltages of up to 100 volts.6.2 DisadvantagesThe following are the drawbacks of using these capacitors:• The capacitance value of these capacitors is less than one microfarad.• These components are also responsible for the Microphonic effect in circuits.• It is unable to withstand high voltages. Since it can easily impact the dielectric present in it. As a consequence, there is a breakdown.Ⅶ Applications for Ceramic CapacitorsGiven that MLCCs are the most commonly manufactured capacitor in the electronics industry, it should come as no surprise that they have a wide range of applications. A resonant circuit in transmitter stations is an interesting high-precision, high-power application. High-voltage laser power supplies, power circuit breakers, and induction furnaces all use Class 2 high-power capacitors. Small-form SMD (surface mount) capacitors are commonly used in printed circuit boards, and capacitors the size of a grain of sand are used in high-density applications. They're also used in DC-DC converters, where high frequencies and high levels of electrical noise put a lot of strain on the components. Since ceramic capacitors are non-polarized and come in a wide range of capacitances, voltage ratings, and sizes, they can be used as a general-purpose capacitor. Ceramic disc capacitors, which are used throughout brush DC motors to reduce RF noise, are familiar to many hobbyists, especially in the field of robotics.Ⅷ How to read ceramic capacitor value?Ceramic capacitors normally have three digits for their values, such as 102, 103, and 101, and the values are in Pico farads. The numbering scheme is simple to understand if you note that picofarads, not microfarads, are used.The worth of a ceramic capacitor with three digits – ABC is AB*10^C Pico Farad. The digit 104 means 10*104pF = 100000pF = 100nF = 0.1uF if ABC is 104. The first two digits of the printed code correspond to the first two digits of the capacitor value, while the third digit indicates the number of zeroes that must be applied to convert the capacitor value to Pico Farad. If we calculate in Nano Farad for values ending with 4, then the reading becomes easy like 104 is 100nF. If we calculate in Nano Farad for values ending with 3, then the reading becomes easy like 103 is 10nF.Some ceramic capacitors are polarized, meaning they have both positive and negative terminals. The capacitor can be identified by its tolerance in addition to its capacitance value. There is many tolerance marking schemes in use, with one and two alphabets being the most common. You don't need to recall them unless you're dealing with a precise circuit. We only looked at ceramic capacitors in direct current (DC) circuits with voltages ranging from 12V to near zero in this short article. Hobbyists are familiar with this collection. It is also useful to be familiar with the tolerance marking scheme for professional purposes. Ⅸ How to Test Ceramic Disc CapacitorCeramic disc capacitors are units used in the computer industry to control voltage for various dielectric functions. Ceramic layers aim to dissipate heat generated by high voltage while also protecting the environment — both internal and external — from damage. Volumetric efficiency is inversely proportional to stability and accuracy with these capacitors, making testing difficult.Step 1 Ceramic capacitors must be tested since they will short out if they are exposed to high voltage. Your monitor can blink or go blank if this happens. This issue can be resolved by removing all of the ceramic capacitors. Ceramic capacitors, on the other hand, can be tested if you have the right tools. Step 2To measure a ceramic capacitor, use a wireless multimeter. The capacitor works properly when the voltage is constant. However, you won't be able to accurately calculate it if the ohmmeter's output and digital capacitance don't match the capacitor's voltage, so the second option is preferable. Step 3To locate the short circuit or assess cases where optical capacitance meters fail to produce shortened readings, use an analog insulation tester. In order to obtain a 12-volt output, set the analog meter to 10 Kohm. This phase is needed for the ceramic capacitor to be tested. You may also use both methods to improve measurement precision if you do want to stop removing the capacitor and test it aboard.Related recommendation: How to Test a Start Capacitor?                                             How to Discharge a Capacitor? Ⅹ FAQ1. What is Ceramic Capacitor?A fixed value type of capacitor where the ceramic material within the capacitor acts as a dielectric is the Ceramic Capacitor. This capacitor consists of more alternating layers with ceramic and also a metal layer which acts as an electrode. The composition of this ceramic material in this capacitor tells about the electrical behavior along with its applications. We can define a ceramic capacitor as A fixed-value capacitor where the ceramic material acts as the dielectric. 2. What are the advantages of ceramic capacitors?Following are the advantages of ceramic capacitors:Manufacturing cost is lessHigh-frequency performance is exhibitedThe stability of the capacitor is dependent on the ceramic dielectric 3. What is the capacitance range for a ceramic capacitor?The typical capacitance range for a ceramic capacitor is 10 pF to 0.1 μF. 4. Can I replace all electrolytic capacitors with ceramic ones?If you can find ceramic capacitors of the correct value, you can certainly do this. Ceramic capacitors are more stable, have a longer useful lifetime, have higher voltage ratings and are not polarized. Be prepared to find that there will be a substantial size difference. 5. What are the differences between electrolytic, tantalum and ceramic capacitors?Ceramic capacitors don't have polarity, their terminals can be interchanged. They are suitable for both ac and dc. They don't have any chemical reaction involved in their work. They have a lesser capacity for the same given size. Electrolytic capacitors have polarity (i.e. they have fixed positive and negative terminal), Suitable for dc only. A chemical reaction involves the formation of aluminum oxide on the electrode. ( Consists of aluminum electrodes in a solution of Ammonium borate).Higher capacity. A tantalum electrolytic capacitor, a member of the family of electrolytic capacitors, is a polarized capacitor whose anode electrode (+) is made of tantalum on which a very thin insulating oxide layer is formed, which acts as the dielectric of the capacitor. A solid or liquid electrolyte that covers the surface of the oxide layer serves as the second electrode (cathode) (-) of the capacitor. 6. What is the time constant for the discharge of the capacitors in (figure 1)?figure 1The equivalent resistance:R= 2*1× 10∧3 = 2000 i©=> the time constant: T= R*C = 2000*1× 10∧-6 = 2×10∧-3s = 2ms 7. How do you read a ceramic capacitor value?The first two digits, in this case, the 10 give us the first part of the value. The third digit indicates the number of extra zeros, in this case, 3 extra zeros. So the value is 10 with 3 extra zeros, or 10,000. Ceramic disc capacitor codes are always measured in pico Farads or pF. 8. How can you tell if a ceramic capacitor is bad?Use the multimeter and read the voltage on the capacitor leads. The voltage should read near 9 volts. The voltage will discharge rapidly to 0V because the capacitor is discharging through the multimeter. If the capacitor will not retain that voltage, it is defective and should be replaced. 9. Do ceramic capacitors degrade over time?Among ceramic capacitors, the capacitance, especially of capacitors classified as a high dielectric constant (B/X5R, R/X7R characteristics), decreases over time. ... When the capacitor cools down below the Curie point, aging starts again. 10. How do you tell the positive and negative of a ceramic capacitor?In general, the ceramic capacitor has no positive and negative poles, and the capacity is generally small. It is often used for signal source filtering, and the polarity is only temporary behavior. This is a kind of non-polar electrolytic capacitor, so it is not polar. 

IntroductionCapacitors are components that store electricity and electrical energy (potential energy) and play an important role in circuits such as tuning, bypassing coupling, and filtering. Capacitors are connected in parallel to increase capacity, and capacitors are connected in series to decrease capacity. When the capacitor is connected in series in the circuit, it can prevent the sudden change of voltage and absorb the overvoltage in the peak state. The series resistance plays a damping role, and the resistance consumes the energy of the overvoltage, thereby suppressing the oscillation of the circuit. When the capacitor is connected in parallel, the parallel resistor can absorb the electric energy of the capacitor, prevent the discharge current of the capacitor from being too large, and avoid damaging the devices (such as thyristors) connected in parallel with it. This is a very comprehensive article including the calculation formulas, circuits, and related common problems of series capacitors and parallel capacitors.Capacitors in Series & Parallel - Electronics BasicsCatalogIntroductionCatalogI What are the Capacitors in Series and Parallel?II Calculation Methods of Capacitance of a Series/Parallel Network  2.1 The Series and Parallel Combination  2.2 Voltage Division  2.3 How to Divide the Voltage When Capacitors are Connected in Series?  2.4 What is the Voltage Division Formula When Connecting 2 Capacitors in Series?III The Equivalent Method of Series or Parallel Connection of Capacitors with Different Rated Voltages and CapacitiesIV Comparison Table of Capacitors in Series and Parallel  4.1 Calculation Comparison of Capacitors in Series and Parallel  4.2 Correspondence Between Magnetic Circuit and Electric Circuit  4.3 Basic Physical Quantities of Magnetic Field and Magnetic CircuitV Frequently Asked Questions about Capacitors in Series and ParallelVI Electrolytic Capacitors in Series  6.1 Function and Purpose of 2 Electrolytic Capacitors in Anti-phase Series  6.2 Is the Electrolytic Capacitor in Series a Non-polarised Capacitor?VII QuizVIII FAQI What are the Capacitors in Series and Parallel?1.1 Parallel Connection of CapacitorsWe can describe the capacitors in parallel as a "water tank", but the water tank stores water, and the capacitor stores electric charges. If multiple capacitors are connected in parallel, they can naturally store more charge.(1) The equivalent capacitance after parallel connection is equal to the sum of the capacitance of each capacitance;(2) The voltage at both ends of each capacitor after parallel connection is equal;The withstand voltage after parallel connection is equal to the smallest capacitor voltage, and the equivalent capacitance is C1+C2, as shown in the figure below.Figure1. Parallel Connection of Capacitors1.2 Series Connection of Capacitors(1) The equivalent capacitance capacity after series connection is equal to the sum of the reciprocal of each capacitance;(2) The capacitance of each capacitor after series connection is equal;(3) The withstand voltage after series connection is equal to the sum of each capacitor voltage.After the capacitor is connected in series, it is equivalent to increase the distance between the two poles. The more the number in series, the smaller the capacitance, but the higher the withstand voltage. In actual circuit design, we generally rarely use capacitors in series, but capacitors in parallel are often used. Sometimes the capacity of a single capacitor is not enough, and one more is added.Figure2. Series Connection of CapacitorsII Calculation Methods of Capacitance of a Series/Parallel Network2.1 The Series and Parallel Combination(1) How to calculate the series capacitance of a capacitor?Suppose there are n capacitors connected in series. The series combination of these n capacitors is connected across a voltage source of V volts. Let us consider that the voltages across capacitors 1, 2, 3...n are V 1, V 2, V 3... Vn, respectively. The capacitances of capacitors 1, 2, 3 ... n are C 1, V 2, V 3 ... C n farad. Since all capacitors are connected in series, each of them will get the same charge, ie it is Q Coulomb. Now we know that the charge at both ends of the capacitor is only the product of the potential difference between the two ends of the capacitor and its capacitance value.Since the series combination of these capacitors is connected across the source of the voltage V volts, replacing the series combination n of multiple capacitors.If we consider a single equivalent capacitor of C,Now we get from equations 1 and 2,Therefore, when multiple capacitors are connected in series, the reciprocal of the equivalent capacitance of the system is given by the arithmetic sum of the reciprocal of their respective capacitances. (2) How to calculate the capacitance in parallel circuits?Suppose there are n capacitors connected in parallel. The parallel combination of these n capacitors is connected across the V volt voltage source. Since the capacitors are connected in parallel to the same voltage source, the charge of each capacitor is different and depends on their respective capacitance values. Let us consider that the charges of capacitors 1, 2, 3...n are Q 1, Q 2, Q 3,..., Q n coulombs, respectively. The capacitances of capacitors 1, 2, 3,..., n are C_1, C_2, C_3,... C_n coulombs respectively. It is now known that a charging capacitor is just the product of the voltage across the capacitor and its capacitance value. therefore,Now instead of connecting multiple capacitors in parallel, if we connect a single equivalent capacitor with capacitance C across the voltage source, then the total charge at both ends of the equivalent capacitor,Since all capacitors are connected in parallelWe can get from equations 1 and 2,Therefore, when multiple capacitors are connected in parallel, the capacitance of the system is given by the arithmetic sum of their respective capacitances.Figure3. (a) Three capacitors are connected in parallel. Each capacitor is connected directly to the battery.              (b) The charge on the equivalent capacitor is the sum of the charges on the individual capacitors. (3) Other related calculation formulasWhen the capacitor is connected in parallel, the area of the electrode is increased, and the capacitance is increased. The total capacity when connected in parallel is the sum of each capacity. When the capacitors are connected in series, the resistance value of the capacitor should be smaller than the insulation resistance of the capacitor in parallel to make the voltage distribution on each capacitor even, so as not to damage the capacitor due to uneven voltage distribution. The series and parallel calculations of capacitors are just the opposite of the series and parallel calculations of resistors.Voltage is the voltage during charging. The relationship between capacity and current, voltage is similar to power and is related to load.When voltage and capacity are quantitative, the smaller the load resistance, the larger the current and the shorter the time.When the voltage and load are quantitative, the larger the capacity, the longer the current and the longer the time.But in the actual discharge circuit, the general load is unchanged, the voltage of the capacitor is gradually reduced, and the current is gradually reduced. (1) Electric capacity (uf) = current (mA)/15Current limiting resistance (Ω)=310/maximum allowable surge currentDischarge resistance (KΩ)=500/capacitance (uf) (2) Calculation method C=15×IC is the capacitance of the capacitor, the unit is microfarad; the i device is the working current, the unit is ampere.For example, if the resistance of a bulb is 0.6 amps, the capacitance should be 15×0.6=9 microfarads, and a 9 microfarad capacitor in series is sufficient. (3) Empirical formula, 1uF output 50mA (if it is linear, a 10000F super capacitor can reach a surge current of 500 megaamps) (4) The calculation of the half-wave rectification method should provide about 30mA current per uF capacitance, which is a reference on the 50Hz220V line in China.The current is doubled in full-wave rectification, that is, 60mA current can be provided per uF.Formula: R*C≥(3～5)*T/2, you need to know the frequency of the lowest signal in the ripple component (that is, the maximum T), and then determine the value of C. ● Capacitor capacityCapacitor capacity indicates the size of electric energy that can be stored. The obstructive effect of capacitors on AC signals is called capacitive reactance. The capacitive reactance is related to the frequency and capacitance of the AC signal. The capacitive reactance XC=1/2πf c (f represents the frequency of the AC signal, and C represents the capacitance of the capacitor). ● The capacity unit and withstand voltage of the capacitor.The basic unit of capacitance is F (farad), and other units include: millifarad (mF), microfarad (uF), nanofarad (nF), picofarad (pF). Since the capacity of the unit F is too large, we generally see units of μF, nF, and pF. Conversion relationship: 1F=1000000μF, 1μF=1000nF=1000000pF. Each capacitor has its withstand voltage value, denoted by V. Generally, the nominal withstand voltage of the electrodeless capacitor is relatively high: 63V, 100V, 160V, 250V, 400V, 600V, 1000V, etc. The withstand voltage of polar capacitors is relatively low. Generally, the nominal withstand voltage values ​​are: 4V, 6.3V, 10V, 16V, 25V, 35V, 50V, 63V, 80V, 100V, 220V, 400V, etc. Power capacitor calculation: such as a three-phase capacitor bank with a nominal voltage of 690v and a capacity of 15kvar. Used in 600v circuit, delta connection, the actual effective capacity is: s=15kvar*600*600/(690*690)=11.34kvar. That is: the capacity and voltage are proportional to the square.2.2 Voltage DivisionDue to the large capacity of large capacitors, the volume is generally large, and they are usually made by multi-layer winding, which leads to a relatively large distributed inductance of large capacitors (also called equivalent series inductance, or ESL for short). The impedance of the inductor to the high frequency signal is very large, so the high frequency performance of the large capacitor is not good. Some small-capacity capacitors are just the opposite. Because of their small capacity, the volume can be made small (shortening the lead wire reduces the ESL, because a piece of wire can also be regarded as an inductance), and flat capacitors are often used Structure, such a small capacity capacitor has a small ESL so that it has a good high frequency performance, but due to the small capacity, the impedance to low frequency signals is large. So, if we want to pass the low frequency and high frequency signals well, we use a large capacitor and then a small capacitor.The commonly used small capacitor is 0.1uF CBB capacitor is better (ceramic capacitor is also OK), when the frequency is higher, you can also connect smaller capacitors in parallel, such as a few pF, hundreds of pF. In digital circuits, a 0.1uF capacitor is generally connected to the ground in parallel to the power pin of each chip (this capacitor is called a decoupling capacitor, of course, it can also be understood as a power filter capacitor, the closer the chip is, the better), because The signal in these places is mainly high-frequency signal, and it is enough to use a smaller capacitor to filter. The impedance of an ideal capacitor decreases as the frequency increases (R = 1/jwc), but an ideal capacitor does not exist. Due to the distributed inductance effect of the capacitor pins, the capacitor is no longer a simple capacitor in the high frequency range. , It should be regarded as a series high-frequency equivalent circuit of capacitance and inductance. When the frequency is higher than its resonance frequency, the impedance shows the characteristic of increasing with the increase of frequency, which is the inductance characteristic. At this time, the capacitance is like An inductance. On the contrary, inductors have the same characteristics. Large capacitors in parallel with small capacitors are widely used in power supply filtering. The fundamental reason is the self-resonance characteristics of the capacitor. The combination of large and small capacitors can well suppress low-frequency to high-frequency power interference signals. Small capacitors filter high frequencies (high self-resonant frequency), and large capacitors filter low frequencies (low self-resonant frequency). The two complement each other. ● Series voltage divider ratio: V1 = C2/(C1 + C2)*V...the larger the capacitance, the smaller the voltage divided, which is the same under AC and DC conditions● Parallel shunt ratio: I1 = C1/(C1 + C2)*I...The larger the capacitance, the larger the current that passes. Of course, this is under AC conditions.Explanation: When two or more capacitors are connected in series, it is equivalent to lengthening the insulation distance, because only the two polar plates on the two sides work, and because the capacitance is inversely proportional to the distance, the distance increases and the capacitance decreases; two or two When the above capacitors are connected in parallel, the area equivalent to the plate increases, and because the capacitance is proportional to the area, the area increases and the capacitance increases. ● Capacitors in series: After the capacitors are connected in series, the capacity decreases and the withstand voltage increases. Formula: 1C1+1C2=1C If two 50uf are connected in series, it becomes 25uf.● Withstand voltage = add the withstand voltage values ​​of two capacitors. If two 100V withstand voltages are connected in series, it becomes 200V.● The formula for calculating the capacity of the series circuit of the capacitor C: 1/C=1/C+1/C2+1/C3+.+1/CnC is the total capacitance value of the capacitor series circuit, C1, C2, C3, Cn are the capacitance values of each capacitor in the capacitor parallel circuit, that is, the reciprocal of the total capacitance of the series circuit is equal to the sum of the reciprocal of the capacitance of each capacitor in the series circuit.Figure4. Capacitors in Series and Parallel2.3 How to Divide the Voltage When Capacitors are Connected in Series?For example 4V voltage source, two capacitors of 0.5F and 1F in series. If it is a DC voltage source, according to the characteristics of capacitor series voltage division introduced in middle school physics:(1) The total voltage across the capacitor series circuit is equal to the sum of the divided voltages across the capacitors. That is, U= U1+ U2+ U3+…+Un.(2) When capacitors are connected in series, the voltage distributed on each capacitor is inversely proportional to its capacitance. That is, Un = Q / Cn (because in the capacitor series circuit, the amount of charge carried on each capacitor is equal, so the larger the capacitor, the lower the voltage, and the smaller the capacitor, the higher the voltage. .)Then the voltage source of 4V, the voltage on the two capacitors of 0.5F and 1F are 8/3V and 4/3V respectively 2. If it is an AC voltage source, from the impedance of the capacitor Xc=1/jωC, we can see |Xc| and C In inverse proportion, the same result can be obtained by using |Xc| as a resistor to calculate the voltage divider.2.4 What is the Voltage Division Formula When Connecting 2 Capacitors in Series?This is a theoretical calculation problem. It is necessary to assume that the withstand voltage value of the capacitor has no margin, that is, a capacitor of 200pF is breakdown when it exceeds 500V; a capacitor of 300pF is breakdown when it exceeds 900V.After adding 1000V voltage, the 200pF capacitor will withstand 600V voltage. Regardless of the capacitor's withstand voltage margin, the 200pF capacitor will break down; at this time, 1000V will all be added to the 300pF capacitor, which exceeds its withstand voltage, so it will breakdown. Calculation formula:If there are M capacitors connected in series, the actual voltage value Un of any capacitor Cn is:Un=U*C/Cn Among them: U is the total voltage; C is the total capacity of M capacitors in series.For two capacitors in series, the formula evolves into:Assuming that the total voltage is U, the voltages on C1 and C2 are U1 and U2 respectively, thenU1=C2*U/(C1+C2)U2=C1*U/(C1+C2)III The Equivalent Method of Series or Parallel Connection of Capacitors with Different Rated Voltages and CapacitiesThe equivalent method of using capacitors with the same rated voltage in series or in parallel is relatively simple and commonly used.Several capacitors with different rated voltages and different capacities are connected in series or in parallel, and the equivalent methods are different. Now give examples to illustrate. There are three capacitors C1: 220µF /10V C2: 100µF/25V C3: 10µF/100VCalculate their parallel and series equivalent values ​​respectively. (1) Parallel equivalent method1) Equivalent capacitanceC and = C1 + C2 + C3= 220µF + 100µF + 10µF/= 330µF2) Equivalent withstand voltageU parallel = U1 = 10V (take the minimum withstand voltage value U1) (2) Series equivalent method1) Equivalent capacitance1/C string ==1/C1 + 1/C2 + 1/C3= 1/220 + 1/100 + 1/10= 252/2200C string == 2200/252≈ 8 (µF)2) Equivalent withstand voltage ● Compare the Q value of each capacitorQ1= C1 X U1 Q2=C2 X U2 Q3=C3 X U3= 220 X 10 =100 X 25 =10 X 100=2200 (C) =2500 (C) =1000 (C)Q = Q3 =1000 (C) (take the minimum power value Q3) ● Find the actual allowable withstand voltage value of each capacitorU1 (actual) = Q/C1 U2 (actual) = Q/C2 U3 (actual) = Q/C3= 1000/220 = 1000/100 = 1000/10≈4.5(V) = 10 (V) =100 (V)3) U string = U1 (actual) + U2 (actual) + U3 (actual)≈4.5 + 10 + 100≈114.5(V)Figure5. Equivalent CapacitanceIV Comparison Table of Capacitors in Series and Parallel4.1 Calculation Comparison of Capacitors in Series and Parallel4.2 Correspondence Between Magnetic Circuit and Electric Circuit4.3 Basic Physical Quantities of Magnetic Field and Magnetic CircuitV Frequently Asked Questions about Capacitors in Series and Parallel(1) Do capacitors charge faster in parallel or series?If two capacitors with the same capacity are connected in parallel or in series in the same circuit, the capacitor in series will charge faster, because the capacity of the capacitor is reduced by half after the capacitor is connected in series, and the charging time becomes shorter. The capacity of the capacitor after parallel connection is doubled, and the charging time will be longer for the same charging circuit. (2) The electric charge of each capacitor in the series circuit is equal. Why is the electric charge of each capacitor equal to the electric charge of the equivalent capacitor?Capacitor voltage: U=Q/CQ=I*tSo U=(I*t)/CWhen the capacitors connected in series are connected to the power supply, the capacitors start to charge. The current flowing through each capacitor is the same. As time goes by, the voltage of each capacitor increases. However, due to the different voltage rise rates of C, the sum of the voltage of each capacitor is equal to the power supply. When the voltage is applied, charging stops and the current is zero. Analyze this process: the current flowing through each capacitor during the entire charging process is the same, and the elapsed time is the same, so the current of each capacitor is the same over time, so the amount of charge is the same and equal to the capacity of the capacitor.Figure6. A Charging State of Three Capacitors in Parallel(3) Are the filter capacitors in the power amplifier power supply connected in parallel?The filter capacitor of the power amplifier power supply is set to eliminate some of the AC components contained in the rectification from AC to DC (the purpose is to improve the audio quality), so all capacitors with larger capacity are selected, generally using electrolysis above tens of microfarads Capacitor. The parallel connection of capacitors is the addition of the capacity of each capacitor, usually forming a standard type 1 filter circuit: "capacitor-resistor (or inductance)-capacitor". If the capacitors are connected in series, the capacity will decrease, it will only increase the cost and occupy more space, meaningless. The power supply line filter capacitor of the amplifier circuit of the power amplifier is generally grouped in parallel. Depending on the design of the power supply, the single power supply circuit may also be directly connected in parallel, or divided into two groups. The two groups are separated by power inductors or resistors into two filter circuits to form a pie-type filter circuit; if it is a dual power supply circuit, , It is generally divided into two groups as for the two groups of power lines. The easiest way to increase the filter capacitor of the power amplifier is to see the positive and negative poles and the rated withstand voltage. Connecting them in parallel can improve the stability of the DC voltage and improve the low-frequency characteristics of the amplifier, making the low frequency of the speaker sound more full and round. Capacitors are generally used in parallel, and capacitors of different capacities filter noise at different frequencies. Large-capacity capacitors can only be realized by electrolytic capacitors. Electrolytic capacitors have positive and negative polarity and are very loud when connected reversely.VI Electrolytic Capacitors in Series6.1 Function and Purpose of 2 Electrolytic Capacitors in Anti-phase SeriesIn some circuit designs, it is seen that two electrolytic capacitors are connected in series in the reverse phase. The capacity of the two components should be equal and the withstand voltage is the same. In AC circuits, the leakage current can be reduced. Just use a non-polar capacitor to get a large-capacity non-polar capacitor. . Large-capacity non-polar capacitors are more expensive. The electrolytic capacitor has a large capacity and is cheap, but it has a polarity, and the two are connected in reverse series. It is non-polar. It can only be used in very low voltage applications (up to 1-2V). The voltage is slightly higher. When the capacitor is used in the opposite direction, the leakage will be large. The accumulated effect will cause the electrolytic capacitor to heat up and eventually cause the capacitor to explode. Electrolytic capacitors are used in DC circuits. So its series connection should be the negative pole of the first one and the positive pole of the second (just like dry batteries in series). But in the circuit, there is indeed a case where the negative poles of two electrolytic capacitors are connected to the negative pole (inverted series), and the two positive poles are used. This is because it is used in an AC circuit (in a circuit where DC and AC coexist), There is no guarantee that the potential of one pole is always higher than the other pole), so that when the capacitor is under reverse voltage, serious leakage current will be generated. At this time, non-polar capacitors should be used, but non-polar capacitors are expensive and expensive. The volume is large, so some people use two electrolytic capacitors to "reverse series".  Its working state is that when there is alternating current, one of them is in the reverse state. Due to its serious leakage, the voltage drop across it is very small. Almost all of the voltage falls on the positive capacitor, and when the other half cycle of the alternating current, the state of the two capacitors will be exchanged, so these two capacitors are used as one, and the total capacitance is equal to any one of them. The total withstands voltage value is equal to 2 times of any capacitor.6.2 Is the Electrolytic Capacitor in Series a Non-polarised Capacitor?Of course, two electrolytic capacitors in parallel will not work. If two electrolytic capacitors are connected in series, it will still not work without applying a proper bias voltage. Applying a bias voltage is quite complicated, especially when both ends of the capacitor (two in series) are not grounded (the bias voltage must be floating). Considering the complexity of applying the bias voltage, it is better not to use this method: connect the negative poles of the two capacitors, and connect the two capacitors in parallel with a high-current diode. The positive of the diode is connected to the negative of the capacitor, and the negative is connected to the positive of the capacitor. Parallel connection of course still has polarity. If reverse parallel connection, it is non-polar, but it is non-polar. Reverse series connection is also not advisable. If you do a test, you will find that there must be a capacitor that withstands the backpressure. If the voltage is large, it will blow up. Unless special measures are taken, the voltage is always applied to the capacitor with the positive voltage. on. Two electrolytic capacitors of the same capacity can be connected in series, but a diode must be connected in anti-parallel to prevent the reverse breakdown of the electrolytic capacitor. After adding a diode, it is okay if it is used for filtering, but it is definitely not good for blocking DC. Because the electrolytic capacitor is only charged and not discharged. Two identical electrolytic capacitors connected in reverse series can replace non-polar capacitors with the same capacity. The dielectric loss of the electrolytic capacitor is very large, and it must be connected to the AC circuit after the voltage is greatly reduced. Otherwise, it is either burned or fried.VII Quiz● QuestionA network of five capacitors of C is connected to a 100 V supply, as shown below figure. Determine(a) the equivalent capacitance of the network(b) the charge on each capacitor. ● SolutionIn the given network, the top three Capacitance is in series, So equivalent capacitance of the top part1C1=1C+1C+1CC1=C3Similarly, the lower two Capacitance is in series, So equivalent capacitance of lower part1C2=1C+1CC2=C2 Now both C1 and C2 are in parallel, so equivalent Capacitance of the NetworkCeq=C1+C2=C3+C2=5C3Now Charge on top part will beQ1=C1V=CV3Now Charge on lower part will beQ2=C2V=CV2  VIII FAQ1. How do you solve capacitors in series and parallel?To calculate the total overall capacitance of a number of capacitors connected in this way you add up the individual capacitances using the following formula: CTotal = C1 + C2 + C3 and so on Example: To calculate the total capacitance for these three capacitors in parallel. 2. How do you know if a capacitor is in series or parallel?In your circuit current, all of the current going to one capacitor must also go to the other. Therefore they are in series. Hope this helps. If two (two-terminal) circuit elements are series-connected, they have identical (not just equal) currents through. 3. What is a capacitor in parallel?Capacitors are connected together in parallel when both of their terminals are connected to each terminal of another capacitor. The voltage ( Vc ) connected across all the capacitors that are connected in parallel is the same. 4. Can you put two capacitors in series?If two or more capacitors are connected in series, the overall effect is that of a single (equivalent) capacitor having the sum total of the plate spacings of the individual capacitors. With resistors, series connections result in additive values while parallel connections result in diminished values. 5. How are capacitors connected in series?Here are the rules for calculating capacitances in series: If the capacitors are of equal value, you're in luck. All you must do is divide the value of one of the individual capacitors by the number of capacitors. For example, the total capacitance of two, 100 μF capacitors is 50 μF. 6. Why capacitor is connected in parallel?Capacitors are devices used to store electrical energy in the form of electrical charges. By connecting several capacitors in parallel, the resulting circuit is able to store more energy since the equivalent capacitance is the sum of individual capacitances of all capacitors involved. 7. Do capacitors in series increase voltage?Capacitors connected in series will have lower total capacitance than any single one in the circuit. This series circuit offers a higher total voltage rating. The voltage drop across each capacitor adds up to the total applied voltage. This is why series capacitors are generally avoided in power circuits. 8. Do capacitors in series or parallel store more energy?The energy stored in a capacitor is a function of the voltage across the capacitor. The voltage will be higher when they are in parallel, so the parallel connection stores the most energy. 9. Why voltage is different in a series combination of capacitors?In a series combination, since the charge stored is the same as the same charge flows through all the capacitors, the potential difference across each will be different. 10. When capacitors are wired in parallel what must be the same for the two capacitors?The charge in the two capacitors is different. Capacitors connected in parallel are connected to the same start and end points of the input and output that's why they have the same potential difference.  

I IntroductionA capacitor is an electronic component composed of an insulator between two conductors, like a sandwich. We can understand it as a container that holds the electric charge. In actual capacitors, two conductors are filled with an insulating dielectric. There are numerous types of dielectrics, so the types of capacitors formed are also different. For example, according to dielectric materials, capacitors can be divided into gas dielectric capacitors, liquid dielectric capacitors, inorganic solid dielectric capacitors, and organic solid dielectric capacitors; according to polarity, they can be divided into polarized capacitors and non-polarized capacitors. This article will introduce the various types of capacitors in detail and some additional basic knowledge of them, mainly explaining from the perspective of the manufacturing process and structure.Capacitors: types, use and testing. CatalogI IntroductionII The Basic Principle of CapacitorsIII Film Capacitor  3.1 Metal Foil Film Capacitor  3.2 Metallized Film CapacitorIV Electrolytic Capacitor  4.1 Aluminum Electrolytic Capacitors  4.2 Tantalum Electrolytic Capacitors  4.3 Niobium Electrolytic CapacitorsV Ceramic Capacitor  5.1 Ceramic Disc Capacitor  5.2 Multi-layer Ceramic Capacitor  5.3 Monolithic Capacitors  5.4 Classification of Ceramic MediaVI SupercapacitorVII Fixed, Trimmer and Variable Capacitors  7.1 Mica Capacitor  7.2 Paper Capacitor  7.3 Trimmer Capacitor  7.4 Variable CapacitorVIII Comparison of Polarized Capacitors and Non-polarized Capacitors  8.1 Medium  8.2 Performance  8.3 Capacity  8.4 Structure  8.5 Application Environments and UseIX Axial and Radial Leaded CapacitorsX A Quiz About Capacitor TypesⅪ FAQII The Basic Principle of CapacitorsCapacitors, along with inductors and resistors, are the three basic passive devices in electronics. The function of the capacitor is to store electrical energy in the form of electric field energy.Taking the parallel plate capacitor as an example, we briefly introduce the basic principle of capacitance.Figure1. Parallel Plate CapacitorAs shown in the figure above, a DC voltage is applied to two metal plates that are close to each other and are parallel to each other (the dielectric between the plates). After stabilization, the metal plate connected to the positive electrode of the voltage will exhibit a certain amount of positive charge, while the metal plate connected to the negative electrode of the voltage will exhibit an equal amount of negative charge. In this way, an electrostatic field is formed between the two metal plates, so the capacitor stores electrical energy in the form of electric field energy, and the stored charge is Q. The amount of charge stored in the capacitor Q is related to the voltage U and its own property (that is, the capacitance value C), that is, Q=U*C. According to the theoretical derivation, the capacitance formula of the parallel plate capacitor is as follows:In this formula:C is the capacitance value, the unit is F (Farad)ε is the dielectric constant of the medium, F/mS is the area of the metal flat plate, m²d is the distance between metal plates, mThe ideal capacitor contains a dielectric, and there is no free charge, so it is impossible to produce charge movement, which is the current.  How does the ideal capacitor pass AC power? AC PowerVoltage can form an electric field inside the capacitor, and alternating voltage will produce an alternating electric field. According to the law of full current in Maxwell's equations:This means that either a current or a changing electric field can generate a magnetic field. Maxwell defines ε(∂E/∂t) as a displacement current, which is an equivalent current and represents the change of the electric field. (The current here represents the current density, or J)Let the AC voltage change sinusoidally, ie:The actual displacement current is equal to the current density times the area:Therefore, the capacitive reactance of the capacitor is 1/ωC. When the frequency is high, the capacitive reactance will be very small, which means passing the high frequency. DC BlockingThe DC voltage does not change with time, the displacement current ε(∂E/∂t) is 0, and the DC component cannot pass through.The characteristics of actual capacitors are non-ideal and have some parasitic effects; therefore, a more complicated model is needed to represent the actual capacitors. The commonly used equivalent model is as follow:Figure2. Equivalent ModelSince the medium is not absolutely insulated, there is a certain conductivity; therefore, any capacitor has a leakage current, expressed by the equivalent resistance Rleak;The conductors and electrodes of the capacitor have a certain resistivity, and there is a certain dielectric loss of the dielectric; these losses are uniformly expressed as the equivalent series resistance ESR;There is a certain inductance in the conductor of the capacitor, which has a greater impact at high frequencies, expressed as the equivalent series inductance ESL;In addition, there is a certain hysteresis in any medium, that is, after the capacitor is quickly discharged, the voltage is suddenly disconnected, and the capacitor will recover part of the charge, which is represented by a series RC circuit（Related post: LC circuit）.Most of the time, the main concern is the ESR and ESL of the capacitor. Quality FactorAs with inductors, the quality factor of the capacitor can be defined, which is the Q value, which is the ratio of the stored power of the capacitor to the power loss:Qc=(1/ωC)/ESRThe Q value is a relatively important parameter for high-frequency capacitance. Self-Resonance FrequencyBecause of the existence of ESL, a resonant circuit is formed together with C, and its resonant frequency is the self-resonant frequency of the capacitor. Before the self-resonant frequency, the impedance of the capacitor becomes smaller as the frequency increases; after the self-resonant frequency, the impedance of the capacitor becomes smaller as the frequency increases, which is inductive. As shown in the following figure:Figure3. Self-Resonance FrequencyAccording to the capacitance formula, in addition to the size of the capacitor, the size of the capacitance is related to the Permittivity of the dielectric. The performance of the dielectric affects that of the capacitor, and different media are suitable for different manufacturing processes.Capacitors can be divided into three main categories according to the manufacturing process: Film Capacitor Electrolytic Capacitor Ceramic CapacitorIII Film CapacitorFilm capacitors are made by winding two plastic films with metal electrodes into a cylindrical shape, and finally encapsulated; because its medium is usually plastic material, also known as plastic film capacitors. Its internal structure is rough as shown in the following figure:Figure4. The Structure of Film CapacitorFilm capacitors can be divided into two categories according to the manufacturing process of their electrodes:3.1 Metal Foil Film Capacitor For metal foil film capacitors, a thin metal foil, usually aluminum foil, is directly added to the plastic film as an electrode. This process is relatively simple, the electrode is easy to lead out, and can be applied to large current occasions.3.2 Metallized Film CapacitorMetalized film capacitors form a thin metal surface directly on the surface of the plastic film by vacuum deposition process as an electrode. Because the thickness of the electrode is very thin, it can be wound into a capacitor with a larger capacity. However, due to the thickness of the electrode, it is only suitable for small current applications.Figure5. Metallized Film ConstructionThe metalized film capacitor has the function of self-repair, that is, if there is a breakdown point inside the capacitor, an avalanche effect will occur at the damaged place, and the vaporized metal will form a vaporized assembly surface at the damaged place, the short circuit disappears, and the damaged point is repaired. Therefore, the reliability of the metalized thin film capacitor is very high, and will not fail due to a short circuit. There are two winding methods for film capacitors:Inductive winding method Before winding, the lead has been connected with the internal electrode.After the non-inductive winding method, gold plating and other processes are used to connect the internal electrodes of the two end surfaces into one surface, so that a smaller ESL can be obtained, and the high frequency performance should be higher.In addition, there is a laminated type non-inductive capacitor, the structure is similar to MLCC, the performance is better, and it is easy to make SMD package.Figure6. Winding MethodsThe characteristic of the film capacitor is that it can achieve large capacity and high withstand voltage. However, due to process reasons, its size is difficult to be small, and it is usually used in strong electric circuits, such as the power electronics industry.Figure7. Winding MethodsIV Electrolytic CapacitorElectrolytic capacitors use metal as an anode, and form a metal oxide film on the surface as a medium, and then wet or solid electrolyte and metal as a cathode. Electrolytic capacitors are mostly polarized. If the metal on the cathode side also has an oxide film, it is a non-polarized electrolytic capacitor.Depending on the metal used, there are three types of electrolytic capacitors:4.1 Aluminum Electrolytic CapacitorsAluminum electrolytic capacitors should be the most widely used electrolytic capacitors and the cheapest. Its basic structure is shown in the following figure:Figure8. The Structure of Aluminum Electrolytic CapacitorThe manufacturing process of aluminum electrolytic capacitors is roughly as follows:First, the aluminum foil will form a very rough surface by electroetching process, which increases the surface area of the electrode and can increase the capacitance;The anode is oxidized by a chemical method to form an oxide layer as a medium;Then, a layer of electrolytic paper is added between the anode aluminum foil and the cathode aluminum foil as a separator, and is pressed and wound;Finally, fill the electrolyte, the electrolytic paper will absorb the electrolyte, and the package is molded.Wet aluminum electrolytic capacitors using electrolyte are the most widely used, with the advantages of large capacitance, high rated voltage, and low cost. The disadvantages are also obvious, that is, shorter life, poor temperature characteristics, and larger ESR and ESL. For hardware development, it is necessary to avoid over-design. In the case of meeting performance requirements, cheap is the biggest advantage.Recommendation: How to Test Aluminum Electrolytic Capacitors4.2 Tantalum Electrolytic CapacitorsThe most widely used tantalum electrolytic capacitor should use manganese dioxide as a solid electrolyte. The internal structure of the solid tantalum electrolytic capacitor is rough as shown in the figure below:Figure9. The Internal Structure of the Solid Tantalum Electrolytic CapacitorCompared with aluminum electrolytic capacitors, the dielectric constant of tantalum oxide (tantalum pentoxide) is much higher than that of aluminum oxide (aluminum oxide). With the same volume, the capacity of tantalum capacitors is larger than that of aluminum electrolytic capacitors. Tantalum capacitors have a longer life and more stable electrical performance.Figure10. The Internal Structure of the Solid Tantalum Electrolytic CapacitorTantalum capacitors also use conductive polymer as electrolyte, the structure is similar to the manganese dioxide tantalum capacitor in the above figure, which is to replace manganese dioxide with a conductive polymer. Conductive polymers have higher conductivity than manganese dioxide, so ESR will be lower. In addition, there are wet tantalum capacitors, which are characterized by super large capacity, high withstand voltage, and low DC leakage current, which is mainly used in military and aerospace fields.Figure11. Wet Tantalum Capacitors4.3 Niobium Electrolytic CapacitorsNiobium electrolytic capacitors are similar to tantalum electrolytic capacitors, in that niobium and its oxides replace tantalum. The dielectric constant of niobium oxide (niobium pentoxide) is higher than that of tantalum oxide (tantalum pentoxide). The performance of niobium capacitors is more stable and more reliable.V Ceramic CapacitorCeramic capacitors use ceramic materials as dielectric materials. There are many types of ceramic materials with different dielectric constants and stability, which are suitable for different occasions.Ceramic capacitors mainly include the following:5.1 Ceramic Disc CapacitorThe main advantage of the ceramic capacitor is that it can withstand high voltage, and it is usually used as a safety capacitor, which can withstand 250V AC voltage. Its appearance and structure are shown below:Figure12. The Structure of Ceramic Disc Capacitor5.2 Multi-layer Ceramic CapacitorMulti-layer ceramic capacitors, that is, MLCCs, chip multi-layer ceramic capacitors are currently the most widely used capacitor types in the world. Their standardized packaging and small size are suitable for automated high-density chip production.The internal structure of the multilayer ceramic capacitor is shown below:Figure13. Internal Structure of Chip Multilayer Ceramic Capacitor5.3 Monolithic CapacitorsBecause multilayer ceramics need to be sintered and porcelainized to form an integrated structure, the multilayer ceramic capacitors in lead packages are also called monolithic capacitors.The structure of monolithic capacitors is that several ceramic film blanks are covered with electrode paddle material, and after being laminated, they are wound into an inseparable whole at a time, and the outside is encapsulated with resin.Monolithic capacitors are a new type of capacitors with small volume, large capacity, high reliability and high-temperature resistance. Low-frequency monolithic capacitors with high dielectric constant also have stable performance and are actively small.5.4 Classification of Ceramic MediaAccording to EIA-198-1F-2002, ceramic media are mainly divided into four categories:Class I: Ceramic medium with temperature compensation characteristics, the dielectric constant is mostly low, not more than 200. It is usually a paraelectric medium. Under temperature, frequency and bias voltage, the dielectric constant is relatively stable and the change is small. The loss is also very low, the dissipation factor is less than 0.01.Figure14. Coding of Class 1 Capacitors According to EIA SpecificationThe most stable and most used is the C0G capacitor, or NP0. NP0 is the code name for the IEC/EN 60384-1 standard as Negative Positive Zero, using N and P for Positive and Negative deviations.Due to the low dielectric constant, the capacitance value of C0G capacitor is small and can be up to 0.1uF. The 0402 package usually has a maximum of 1000pF. Class II, III: Among them, the temperature characteristic A-S belongs to Class II, and the dielectric constant is about several thousand. The temperature characteristic T-V belongs to Class III, and the dielectric constant can be as high as 20000. It can be seen that the performance of Class III is more unstable. According to the classification of IEC, both Class II and III belong to the second category, high dielectric constant media. For example, X5R and X7R are Class II capacitors, which are widely used in power supply decoupling, while Y5V belongs to Class III capacitors, and their performance is not stable.Figure15. EIA Coding of Class 2 and 3 CapacitorsThe capacitance value of Class II and III capacitors can be up to several hundred uF, but due to the high dielectric constant medium, most of them are ferroelectric medium (Ferroelectric), and the temperature stability is poor. In addition, the dielectric constant of ferroelectric media will decrease under DC bias voltage. Class IV: The manufacturing process is different from the usual ceramic materials. The internal ceramic particles are all a thin oxide layer on the outside, and the core is a conductor. This type of capacitor has a large capacity but a small breakdown voltage. Due to the unstable performance and high loss of these capacitors, they have been basically eliminated.VI SupercapacitorSupercapacitor refers to a new type of energy storage device between a traditional capacitor and a rechargeable battery. There are two ways to store charge: EDLC and pseudocapacitance. It not only has the characteristics of rapid charge and discharge of the capacitor but also has the energy storage characteristics of the battery. The capacity of the supercapacitor is particularly large. It can replace the battery as a power supply device, and can also be used in conjunction with the battery. Supercapacitors charge fast, can be fully charged and discharged, and can be charged to any desired voltage, as long as the rated voltage is not exceeded. There are many applications of supercapacitors, for example, many cities in China have supercapacitor electric buses. There are also applications in some electronic products, such as some driving recorders, which can continue to supply power for several days.Figure16. SupercapacitorsVII Fixed, Trimmer and Variable CapacitorsA capacitor with a fixed capacitance is called a fixed capacitor. According to the different media can be divided into ceramics, mica, paper, film, electrolysis. Having described film capacitors, electrolytic capacitors, and ceramic capacitors, let's look at the other two types of fixed capacitors.  7.1 Mica CapacitorMica capacitors can be divided into foil type and silver type. Silver electroplating is very direct on mica sheets by vacuum evaporation or sintering method. Due to the elimination of the air gap, the temperature coefficient is greatly reduced and the capacitance stability is higher than foil type. Mica capacitors are widely used in high-frequency electrical appliances and can be used as standard capacitors. The glaze capacitor is made of a special mixture with a concentration suitable for spraying into a film. The medium is then sintered with a silver layer electrode to form a "monolithic" structure. Glass glaze capacitor is comparable to a mica capacitor in performance and can withstand various climates. It can generally work at 200℃ or higher, with rated working voltage up to 500 V and loss tan = 0.0005 ~ 0.008.Figure17. Silver Mica Capacitors7.2 Paper CapacitorPaper capacitors are widely used in radio and electronic equipment. Generally, two aluminum foils are used as electrodes, which are separated by overlapping winding of capacitor paper with a thickness of 0.008 ~ 0.012 mm. Simple manufacturing process, low price, can obtain a large capacitance, generally below 0.25 F, but the capacity error is large and difficult to control, good quality is ±10%, loss (tan ≤ 0.015), temperature and frequency characteristic stability is poor. The paper capacitors commonly used in the past are non-sealed, impregnated only with ground wax, paraffin wax and chlorinated diphenyl, etc., which are prone to aging and poor stability. They are easily affected by humidity, insulation resistance decreases after being affected by moisture, and atmospheric pressure also affects them. The paper capacitor whose core is sealed inside the metal or ceramic tube is of good quality and has little influence on the external climatic conditions. It can be normally used in the situation with the relative humidity up to 95 ~ 98 %. The electrode of metalized paper capacitor uses vacuum evaporation to directly attach the metal to the capacitor paper, which is only about 1/4 of the volume of the ordinary paper capacitor. Its main feature is its "self-recovery" function, that is, it can be "self-healing" after a breakdown. It is an improved type of paper capacitor. Oil-immersed capacitors have a higher voltage than ordinary paper capacitors, good stability, suitable for high-voltage circuits.Paper capacitors are intermediate frequency capacitors, which are generally used in low-frequency circuits and usually cannot be used in frequencies higher than 3 ~ 4 MHz.Figure18. Paper Capacitor7.3 Trimmer CapacitorTrimmer capacitors, also called semi-variable capacitors, have a capacitance that can be adjusted within a small range and fixed to a certain capacitance value after adjustment.Ceramic trimmer capacitors are of high quality and small size, and can usually be divided into two types: round tube type and round chip type.Trimmer capacitors for mica and polystyrene media are usually of spring-loaded structure, which is simple in structure but less stable.The wire-wound porcelain trimmer capacitor is used to change the capacitance by removing the copper wire (external electrode), so the capacitance can only be reduced and is not suitable for repeated debugging.7.4 Variable CapacitorAs the name implies, a variable capacitor means that the capacitance value can vary over a large range and can be determined to a certain value. Variable capacitors are divided into two forms: film medium and air medium. It is commonly used in coupling and tuning circuits, such as double capacitors, ceramic capacitors and so on.VIII Comparison of Polarized Capacitors and Non-polarized Capacitors8.1 MediumWhat is the medium? To put it bluntly, is the substance between the two plates of the capacitor. Most polarized capacitors use an electrolyte as the dielectric material. Generally, capacitors of the same volume have large polar capacitance. In addition, different electrolytic materials and processes produce polarized capacitors of the same volume. Furthermore, pressure resistance is also closely related to the use of dielectric materials. There are likewise many non-polarized capacitor dielectric materials, most of which use metal oxide film and polyester. Because the reversible or irreversible performance of the medium determines the use environment of polarized and non-polarized capacitors.8.2 PerformancePerformance is the requirement for use, and maximum demand is the requirement for use. If the metal oxide film capacitor is used for filtering in the power supply part of the TV, the capacitor capacity and withstand voltage required by the filtering must be achieved. Maybe only a power supply can be installed in this case. Therefore, only polarized capacitors can be utilized for filtering, and these capacitors are irreversible. In other words, the positive electrode must be connected to the high potential end, and the negative electrode must be connected to the low potential end. Generally, the electrolytic capacitor is above 1 microfarad for coupling, decoupling, power supply filtering, etc. Non-polarized capacitors are mostly below 1 microfarad, participating in resonance, coupling, frequency selection, current limiting, etc. Of course, there are also large-capacity and high-pressure-resistant ones, which are mostly used for reactive power compensation of electric power, phase shifting of motors, and frequency shifting power supply. There are many types of non-polarized capacitors, so this article won’t go into detail.Figure19. Classification of Capacitors8.3 CapacityAs mentioned earlier, the electrical media of the same volume are different, so the capacity is not equal.8.4 StructureIn principle, any shape capacitors can be used in the environment without considering the tip discharge. The electrolytic capacitors (polarized capacitors) that are usually used are round, and the square ones are rarely utilized. The shape of non-polarized capacitors varies. Like tube shape, deformed rectangle, sheet shape, square shape,combined square shape and round shape, etc., see where it is used. Of course, there are invisible. Intangible here refers to distributed capacitance. The distributed capacitance must not be ignored in high-neck and intermediate-frequency devices.8.5 Application Environments and UseIn the repair of home appliances, all of the above may be found. If you want to understand in a simple way, you have to find out by yourself.Because of the relationship between its internal materials and construction, the capacity of polarized capacitors (such as aluminum electrolysis) can be very large, but its high-frequency characteristics are not good, so it is suitable for power supply filtering and other occasions, but there are also good high-frequency characteristics. Polarized capacitor-tantalum electrolysis, its price is relatively high; Non-polarized capacitors are small in size, low in price, and satisfactory in high-frequency characteristics, but they are not suitable for large capacity. Like ceramic capacitors, monolithic capacitors, and polyethylene (CBB) capacitors, ceramic capacitors are generally used in high-frequency filtering and oscillation circuits.Figure20. Axial and Radial Type ConstructionIX Axial and Radial Leaded CapacitorsOne method of packaging capacitors is the lead structure. 　　Axial capacitance refers to the capacitance of the two pole leads on the same axis. Generally, it is a non-inductive structure. It is made of metalized polyester film as the dielectric/electrode. The wire is tinned copper clad steel wire (or flexible wire), the outer layer is wrapped with polyester tape, and both ends are sealed with epoxy resin.Figure21. Axial Lead StructureAxial leads (the leads are on the same plane as the capacitor axis) are radial leads. The figure below shows an example of a radial lead. The lead is in the radial position of the capacitor. Critical dimensions are lead spacing "S", height "H", length "L" and thickness "P'. Because they are inserted on the printed circuit board rather than on the surface of the circuit board like surface mount components, axial And radial elements are collectively referred to as "plug-in elements".Figure22. Radial Lead StructureX A Quiz About Capacitor TypesQuestion:The capacitors which use chemical reactions to store charge are calledA.ceramic capacitorsB.fixed capacitorsC.parallel plate capacitorsD.electrolytic capacitorsAnswer:D Ⅺ FAQ1. How do you identify a capacitor?Ceramic types of capacitors generally have a 3-digit code printed onto their body to identify their capacitance value in pico-farads. Generally, the first two digits indicate the value of the capacitor and the third digit indicates the number of zero's to be added. 2. What are the 2 types of capacitors?Capacitors are divided into two mechanical groups: Fixed capacitors with fixed capacitance values and variable capacitors with variable (trimmer) or adjustable (tunable) capacitance values. The most important group is the fixed capacitors. Many got their names from the dielectric. 3. Can a 440v capacitor be used for a 230v application?The 440 volts listed on the cap is the maximum allowable voltage the capacitor can handle. You could actually use a 370-volt cap on 230 volts. ... Capacitor is connected in series with the auxiliary winding of the motor. Since winding is inductive, the voltage across the capacitor is much higher than the supply voltage. 4. What side of the capacitor is positive?Electrolytic capacitors have positive and negative sides. To tell which side is which, look for a large stripe or a minus sign (or both) on one side of the capacitor. The lead closest to that stripe or minus sign is the negative lead, and the other lead (which is unlabeled) is the positive lead. 5. What does 50 uF mean on a capacitor?It's a symbol that means micro so 50 μF means 50 microfarads or 000050 Farads. The farad is such a large unit that the microfarad is the practical unit for capacitance. 6. What are capacitors in parallel called?When capacitors are connected in parallel, the total capacitance is the sum of the individual capacitors' capacitances. If two or more capacitors are connected in parallel, the overall effect is that of a single equivalent capacitor having the sum total of the plate areas of the individual capacitors. 7. Are AC and DC capacitors interchangeable?You can use AC caps on DC. AC caps have a much higher DC rating. All capacitors have microscopic air bubbles between the foil layers. DC is just a special case where the polarity of the voltage does not change, so you can use AC capacitors - as is - in a DC application. 8. Which type of capacitor is polarized?The only type of capacitor that is polarized (works differently depending on which way the current is flowing) is the electrolytic capacitor. Electrolytic capacitors have higher capacitance, but for most purposes, the non-polarized capacitor is preferred. 9. What is the main function of the capacitor?A capacitor is an electronic component that stores and releases electricity in a circuit. It also passes alternating current without passing direct current. A capacitor is an indispensable part of electronic equipment and is thus almost invariably used in an electronic circuit. 10. What happens if you use the wrong size capacitor?If the wrong run capacitor is installed, the motor will not have an even magnetic field. This will cause the rotor to hesitate at those spots that are uneven. This hesitation will cause the motor to become noisy, increase energy consumption, cause performance to drop, and cause the motor to overheat. 

I IntroductionTwo adjacent conductors are sandwiched by a layer of a non-conductive insulating medium to form a capacitor. Capacitors are one of the most commonly used electronic components. They play an important role in circuits like tuning, bypassing, coupling, and filtering. For example, they are often used in the tuning circuit of the transistor radio, coupling circuit and bypass circuit of the color TV. This article mainly introduces how to properly use multimeters to test capacitors and aluminum electrolytic capacitors (solid state capacitor), including detailed operating steps, working principles, notice, and explaining some fundamental knowledge about capacitors. We also have a related post about how to check start capacitors you may be interested in. Don't miss it! How to Test Capacitors with a Digital MultimeterCatalogI IntroductionII Definition of CapacitorIII The Reasons and Effects of Testing Capacitors and Withstand Voltage Performance  3.1 Why Should We Measure the Capacitance of A Capacitor?  3.2 Why Should Capacitors Undergo A Withstand Voltage Test?IV The Difference of Capacitors with Different Capacity in Test  4.1 Small-capacity Capacitor Test  4.2 Large-capacity Capacitor Test  4.3 Supercapacitor TestV How to Test Capacitors with A Multimeter?  5.1 Direct Test with A Capacitor  5.2 Test with Resistance File  5.3 Test with Voltage File  5.4 Test with Buzzer  5.5 Use a Digital Multimeter to Measure Capacitance Greater Than 20μFVI How to Detect Capacitors in Aluminum Capacitors  6.1 Appearance Physical Inspection  6.2 Capacity and Loss Test  6.3 Ripple Voltage Test  6.4 Leakage Current Test  6.5 Explosion Test  6.6 Temperature TestVII Considerations for Capacitor TestingVIII One Question Related to Testing Capacitor  8.1 Question  8.2 AnswerⅨ Frequently Asked Questions about How to Test a CapacitorII Definition of CapacitorCapacitors comprise components that store electricity and electrical energy (potential energy). A conductor is surrounded by another conductor, or the electric field lines emitted by one conductor all terminate in the conduction system of the other conductor, called a capacitor. This is a short introduction of capacitor. Under what circumstances do you need to test the capacitors, that's when you have capacitor uncertainty in use. So let's analyze it here. III The Reasons and Effects of Testing Capacitors and Withstand Voltage Performance3.1 Why Should We Measure the Capacitance of A Capacitor?The purpose of measuring the capacitance value of a capacitor in a general sense of electricity is to check the change of its capacitance value. By comparing the measured value with the value on the nameplate, you can judge whether the internal wiring is correct and whether the insulation has deteriorated because of moisture, whether the component has broken down, and whether oil leakage has caused the capacitance to decrease. So be careful during the substantial operation. 3.2 Why Should Capacitors Undergo A Withstand Voltage Test?The withstand voltage test refers to the test of the capability of withstanding voltage of various electrical devices and structures. The process of applying a high voltage to an insulating material or an insulating structure without damaging the performance of the insulating material is considered a withstand voltage test. Broadly speaking, the primary purpose of the capability of withstanding voltage test is to check the ability of the insulation to withstand working voltage or overvoltage, and then to check whether the insulation performance of the product equipment meets safety standards capability of withstanding voltage test is to check the ability of the insulation to withstand working voltage or overvoltage, and then to check whether the insulation performance of the product equipment meets safety standards.Figure1. Capacitor TestingIV The Difference of Capacitors with Different Capacity in Test4.1 Small-capacity Capacitor TestThe capacitance of a small-capacity capacitor is generally below 1 UF because the capacity is too minor, the charging phenomenon is unobvious, and the angle of the hand to the right is not large when measuring. Therefore, it is generally impossible to estimate its capacitance with a multimeter, but only to detect whether it has leakage or breakdown. Under normal conditions, the resistance value of both ends of the multimeter R × 10 k should be infinite. If the certain resistance value is measured or the resistance value is close to 0, it means that the capacitor has leaked electricity or has been damaged by a breakdown.Related recommendation: How to Test Ceramic Disc Capacitor 4.2 Large-capacity Capacitor TestLarge capacity can generally be tested by 1K-10K, see the sweep of the meter during charging, and the resistance value indicated by the last meter. The closer to the left, the better. If the resistance is too small, it cannot be used. 4.3 Supercapacitor TestThe method of measuring supercapacitors is completely different from other types of capacitors. Supercapacitors have exceptionally large capacitance values that cannot be measured directly by standard equipment. Ordinary methods for testing the capacitance of these capacitors are by charging the supercapacitors at the rated voltage and discharging the supercapacitors by a constant current load.Figure2. Different CapacitorsV How to Test Capacitors with A Multimeter?5.1 Direct Test with A CapacitorSome digital multimeters have the function of measuring capacitance, and their ranges are divided into five ranges of 2,000p, 20n, 200n, 2μ and 20μ. When measuring, you can directly insert the two pins of the discharged capacitor into the Cx jack on the meter board and select the appropriate range to read the display data. 2,000p file, suitable for measuring capacitance less than 2000pF; 20n file, suitable for measuring the capacitance between 2000pF and 20nF; 200n file, suitable for measuring the capacitance between 20nF and 200nF; 2μ file, suitable for measuring between 200nF and 2μF Capacitance; 20μ range, suitable for measuring the capacitance between 2μF and 20μF. Experience has shown that some types of digital multimeters (like DT890B +) allow a considerable error when measuring small-capacity capacitors below 50pF, and there is almost no reference value for measuring capacitance below 20pF. At this time, the small value capacitance can be measured by the series method. Method: First find a capacitor of about 220pF, use a digital multimeter to measure its actual capacity C1, and then connect the small capacitor to be tested in parallel to measure its total capacity C2. The difference between the two (C1-C2) is subsequently the capacity of small capacitors under test.It is extremely accurate to measure the small capacitance of 1 ~ 20pF with this method.Figure3. How to Test a Capacitor with a Multimeter5.2 Test with Resistance FileThe practice has proved the charging process of capacitors can also be observed by using a digital multimeter, which actually reflects the change of charging voltage in discrete digital quantities. Assuming that the digital multimeter's measurement rate is n times/second, in the process of observing the charging of the capacitor, you can see n readings that are independent of each other and increase sequentially. According to this display characteristic of the digital multimeter, it is possible to detect the quality of the capacitor and estimate the size of the capacitance. The following describes the method of detecting the capacitor using the resistance meter of a digital multimeter, which is of practical value for instruments without a capacitor. This method is suitable for measuring large-capacitance capacitors from 0.1 μF to several thousand microfarads. 5.2.1 Operation Method of MeasurementAs shown in Figure 4, set the digital multimeter to the appropriate resistance level. The red and black test leads respectively to touch the two poles of the capacitor Cx under test. At this time, the displayed value will gradually increase from "000" until the display Overflow symbol "1."If"000" is consistently displayed, it means the capacitor is short-circuited internally; if it is constantly displayed, the internal poles of the capacitor may be open-circuited, or the selected resistance level may be inappropriate. When checking electrolytic capacitors, pay attention to the red test lead (positive charge) is connected to the positive electrode of the capacitor, and the black test lead is connected to the negative electrode of the capacitor.Figure4. Digital Multimeter 5.2.2 Measurement PrincipleFigure5 shows the measurement principle of measuring capacitors with resistance files. During the measurement, the positive power source charges, the capacitor Cx to be measured through the standard resistor R0. At the moment when charging starts, Vc = 0, so “000” is displayed. As Vc gradually increases, the displayed value increases. When Vc = 2VR, the meter starts to display the overflow symbol "1." The charging time t is the time required for the displayed value to alter from "000" to overflow. This time interval can be measured with a quartz meter.Figure5. Principle of Measurement 5.2.3 Measured Data Using DT830 Digital Multimeter to Estimate CapacitanceThe principle of selecting the resistance range is: when the capacitance is small, a high resistance should be selected, and when the capacitance is large, a low resistance should be selected. If you use a high-resistance range to estimate a large-capacity capacitor, the measurement time will last a long time because the charging process is very slow. If you use a low-resistance range to check a small-capacity capacitor, the meter will always show an overflow because the charging time is extremely short, and you cannot see the change. 5.3 Test with Voltage FileDetecting capacitors with the DC multimeter of a digital multimeter is actually an indirect measurement method. This method can measure small-capacitance capacitors from 220pF to 1μF, and can accurately measure the capacitor leakage current.5.3.1 Measurement Methods and PrinciplesThe measurement circuit is shown in Figure6. E is an external 1.5V dry battery. Set the digital multimeter to the DC 2V range, connect the red test lead to one electrode of the capacitor Cx under test, and the black test lead to the battery negative. The input resistance of the 2V range is RIN = 10MΩ. After the power is turned on, battery E charges Cx via RIN and starts to establish voltage Vc. The relationship between Vc and charging time t isFigure6. Wiring Diagram of Measuring Capacitor with Voltage Block Here, because the voltage across RIN is the instrument input voltage VIN, so RIN actually has the function of a sampling resistor. obviously,VIN (t) = E-Vc (t) = Eexp (-t / RINCx) (5-2)Figure7 is the change curve of the input voltage VIN (t) and the charging voltage Vc (t) on the capacitor under test. It can be seen from the figure that the change process of VIN (t) and Vc (t) is just the opposite. The curve of VIN (t) decreases with time, while Vc (t) increases with time. Although the meter shows the change process of VIN- (t), it indirectly reflects the charging process of the capacitor Cx under test. During the test, if Cx is open (no capacity), the displayed value will always be “000”. If Cx is internally short-circuited, the displayed value will always be the battery voltage E and will not change with time.Figure7. Change Curve of VIN (t) and Vc (t) Equation (5-2) shows that when the circuit is turned on, t = 0, VIN = E, the initial display value of the digital multimeter is the battery voltage, and then as Vc (t) increases, VIN (t) gradually decreases. Until VIN = 0V, the Cx charging process ends, at this timeVcx (t) = EUsing digital multimeter voltage level detection capacitor, not only can check small-capacitance capacitors from 220pF to 1μF, but also measure the capacitor leakage current. Let the leakage current of the capacitor being measured be ID, and the stable value displayed by the meter at the end is VD (the unit is V), thenFigure8. Equation (5-3) 5.3.2 ExamplesExample 1:The measured capacitance is a 1μF / 160V fixed capacitor, using the 2VDC range of the DT830 digital multimeter (RIN = 10MΩ). Connect the circuit according to Figure6. Initially, the meter displayed 1.543V, and then the displayed value gradually decreased. After about 2 minutes, the displayed value stabilized at 0.003V. Find the leakage current of the capacitor under test.Figure9. Equation The leakage current of the capacitor under test is only 0.3nA, indicating good quality.Example 2:The capacitor under test is a 0.022μF / 63V polyester capacitor. The measurement method is the same as in Example 1. Due to the small capacity of this capacitor, VIN (t) decreases rapidly during measurement, and after about 3 seconds, the displayed value decreases to 0.002V. Substituting this value into equation (5-3), the leakage current was calculated to be 0.2nA. 5.3.3 Notes(1) Before measurement, the two pins of the capacitor should be short-circuited and discharged, otherwise, the change process of the reading may not be observed.(2) Do not touch the capacitor electrode with both hands during the measurement to avoid meter jumping.(3) During the measurement, the value of VIN (t) changes exponentially, and decreases rapidly at the beginning. With the increase of time, the decline rate will become slower and slower. When the capacitance of the capacitor Cx under test is less than a few thousand picofarads, because VIN (t) initially drops too quickly, and the meter's measurement rate is too low to reflect the original voltage value, the initial display value of the meter is lower than the battery Voltage E.(4) When the measured capacitor Cx is greater than 1 μF, in order to shorten the measurement time, a resistance file can be used for measurement. However, when the capacitance of the capacitor under test is less than 200pF, it is difficult to observe the charging process because the change in the reading is very short. 5.4 Test with BuzzerUsing the buzzer file of the digital multimeter, you can quickly check the quality of the electrolytic capacitor. The measurement method is shown in Figure10. Set the digital multimeter to the buzzer position, and use two test leads to contact the two pins of the capacitor Cx under test. A short beep sound should be heard, the sound will stop, and the overflow symbol "1" will be displayed. Then, measure the two test leads again, and the buzzer should sound again, and the overflow symbol “1” will be displayed at last, which indicates that the electrolytic capacitor under test is basically normal. At this time, you can dial to 20MΩ or 200MΩ high resistance to measure the leakage resistance of the capacitor to determine its quality.Figure10. Wiring Diagram For Testing Electrolytic Capacitor with Buzzer The principle of the above measurement process is: At the beginning of the test, the charging current of the instrument to Cx is large, which is equivalent to the path, so the buzzer sounds. As the voltage across the capacitor continues to increase, the charging current rapidly decreases, and finally, the buzzer stops sounding. During the test, if the buzzer keeps sounding, it means that the internal of the electrolytic capacitor has been short-circuited. If the buzzer keeps sounding and the meter always shows "1" when the meter pen is repeatedly measured, it means that the capacitor under test is open or the capacity disappears. 5.5 Use a Digital Multimeter to Measure Capacitance Greater Than 20μFFor common digital multimeters, the maximum measurement value of the capacitance file is 20 μF, which sometimes cannot meet the measurement requirements. For this reason, the following simple method can be used to measure the capacitance of more than 20μF with the capacitance file of the digital multimeter, and the maximum capacitance of several thousand microfarads can be measured. When using this method to measure large-capacitance capacitors, there is no need to make any changes to the original digital multimeter circuit. The measurement principle of this method is based on the formula C string = C1C2 / (C1 + C2) of two capacitors in series. Since two capacitors with different capacities are connected in series, the total capacity after the series connection is smaller than that of the capacitor with the smaller capacity. Therefore, if the capacity of the capacitor to be measured exceeds 20 μF, only one capacitor with a capacity of less than 20 μF is used. In series with it, you can measure directly on the digital multimeter. According to the formula of two capacitors in series, it is easy to derive C1 = C2C string / (C2-C string). Using this formula, the capacitance value of the measured capacitor can be calculated. Here is a test example to illustrate the specific method of using this formula. The component under test is an electrolytic capacitor with a nominal capacity of 220 μF, and is set to C1. Select an electrolytic capacitor with a nominal value of 10μF as C2, use a digital multimeter 20μF capacitor to measure the actual value of this capacitor as 9.5μF, and connect the two capacitors in series to measure the C string as 9.09μF. Substituting C2 = 9.5 μF and C string = 9.09 μF into the formula, thenC1 = C2C string / (C2-C string) = 9.5 9.09 / (9.5-9.09) ≈211 (μF)Figure11. Digital MultimeterNote: No matter how much the capacity of C2 is selected, a capacitor with a larger capacity must be selected under the premise of less than 20μF, and C2 in the formula should be substituted into the actual measured value instead of the nominal value, which can reduce errors. The two capacitors are connected in series and measured with a digital multimeter. Due to the capacitance error and measurement error of the capacitor itself, as long as the actual measured value is close to the calculated value, the capacitor C1 to be measured is considered good. capacity. In theory, this method can measure the capacitance of any capacity, but if the capacity of the capacitor under test is too large, the error will increase. The error is proportional to the size of the capacitor to be measured.Do you want to know about other tools to test capacitors? You can Three Measuring Tools to Test Capacitors. VI How to Test Aluminum Electrolytic Capacitors6.1 Appearance Physical Inspection(1) First check whether the capacitor under test has a formal "Product Specification", which includes the product name, specifications, installation dimensions, process requirements, technical parameters, and supplier name, address and contact information to ensure this. Batch products are provided by regular manufacturers. The logo on the capacitor should include the trademark, working voltage, standard capacitance, polarity, and operating temperature range. (2) Refer to the process parameters in the “Product Specification” and observe whether the appearance, color, and material of the capacitor are consistent with the process indicators marked on it. (3) Use a vernier caliper to confirm the installation size of the capacitor to ensure that the diameter, height, and diameter and spacing of the lead-out terminal are within the tolerance of the product process, and the external dimensions must meet the company's selection requirements. (4) Check the appearance of the capacitor to ensure its appearance is neat, without obvious deformation, breakage, cracks, spots, dirt, rust, etc., and its marking is clear, firm, correct and complete. (5) Check the lead-out terminals to ensure that their terminals are straight, free from oxidation, rust, and have no effect on their conductive properties and that the lead-out terminals are free of distortion, deformation, and mechanical damage that affects insertion and removal. (6) Check that the production date marked on the electrolytic capacitor should not exceed six months, and make a record.Figure12. Aluminum Electrolytic Capacitor6.2 Capacity and Loss Test(1) Use the electric bridge to test whether the actual capacity is consistent with the nominal capacity (the electrolytic capacitor generally has an error range of ± 20%). The loss tangent value tanθ (that is, the D value) is in compliance with the standard. (2) How to use the Zen tech bridge tester: After connecting the power supply correctly, press the "POWER" key to turn on the tester's working voltage; press the "LCR" key to select the test type (L: Inductance, C: Capacitance, R: resistance). (3) Press the "UP" and "DOWN" keys to select the test range (μF, nF, pF) and press the "FREQ" key to select the test frequency (100HZ,(120HZ, 1KHZ) can choose the required test frequency according to the technical parameters provided by the manufacturer, the test in this article selects "100HZ". (4) Press "SERIES" (parallel) and "PARALLEL" (parallel) to select the connection mode for the test, small capacitance (less than 10μF)To use parallel mode, use large mode (10μF and above) in series mode. (5) After the setting is completed, connect the bridge test ports ("LOW" and "HIGH") to the two ends of the capacitor, and use the label paper to record the capacity value and loss value on the display respectively. And attach the label paper to the corresponding capacitor for subsequent analysis. 6.3 Ripple Voltage Test(1) Connect the circuit as shown below, and connect the capacitor to be tested to the adjustable DC power supply (note that the positive and negative poles are not connected reversely). Connect the positive electrode of the oscilloscope probe with a non-inductive capacitor (1μF 1200V.DC) in series to the positive electrode of the capacitor to be tested.Figure13. Circuit of Ripple Voltage Test (2) For the setting of the oscilloscope, it must be set to the DC test position first, and the fine adjustment knob of the oscilloscope voltage must be locked. (3) During the test, the DC voltage should be slowly increased to the rated voltage with a voltage regulator, and the changes displayed by the oscilloscope should be closely monitored. The correct range should be selected to ensure that the voltage can be accurately read from the oscilloscope waveform. (4) Take the ripple waveform with the camera, and record the range and division of the oscilloscope with label paper (that is, calculate the ripple voltage and paste it on the corresponding capacitor for subsequent analysis and comparison. (5) After the recording is completed, disconnect the DC power supply, discharge the capacitor under test and the non-inductive capacitor with the bulb load, and then remove the capacitor under test from the test bench. 6.4 Leakage Current Test6.4.1 Indirect Measurement Method OneConnect as shown below. Connect a 1K resistor in series with the capacitor under test and connect it to a DC adjustable power supply. Use an oscilloscope probe to connect to both ends of the resistor. Indirectly calculate the leakage current of the capacitor to be measured by sampling the voltage signal across the resistor. Operating essentials and precautions: After the circuit is connected, adjust the DC adjustable power supply to the rated voltage of the capacitor. After the circuit is equilibrated for two minutes, read the voltage value across the resistor. When reading the oscilloscope, the voltage trimming knob should be locked. Record the maximum value of the voltage waveform as the voltage value and divide it by the resistance value to obtain the value of the leakage current. The current is too large and the resistor is burned out. After the test, the capacitor should be discharged and then removed to avoid accidents.Figure14. Circuit 6.4.2 Indirect Measurement Method TwoConnect the wiring as shown in the figure, and add an air switch in series between the capacitor and the DC power supply. First close S1 and S2 respectively, and adjust the voltage regulator to the rated voltage to charge the capacitor for two minutes.Figure15. Circuit After that, both S1 and S2 are disconnected. At this time, the adjustable power supply is at the rated value. Do not move. Add a milliamp meter between S1 and S2, as shown in the figure below: S1 and S2 are both closed, and the leakage current can be directly read through the milliamp meter after one minute of stabilization.Figure16. Circuit 6.4.3 PrecautionsRemember not to connect the milliamp meter to the line directly when the capacitor is not charged, because the initial charging current is large, the milliamp meter will be burned out by accident. In the disassembly process, first discharge the capacitor with the bulb load. When discharging, remove the milliamp meter first, and ensure that the discharge current does not pass the test resistor to prevent damage to the test resistor and the millimeter meter.6.4.4 Leakage Current at 1.2UnAdjust the DC voltage to 1.2 times the rated voltage of the electrolytic capacitor, measure its leakage current again and compare different samples. 6.5 Explosion Test6.5.1 DC TestApply reverse DC voltage to the capacitor under test, slowly adjust the adjustable DC voltage, and observe the current closely with a clamp meter.The DC power setting is generally not more than 30V. The current value is set according to the size of the capacitor as follows:When the capacitor diameter is 6mm ≤ 22.4mm, the current cannot exceed 1A; when the capacitor diameter is> 22.4mm, the current cannot exceed 10A. 6.5.2 Observe The Surface Temperature of The CapacitorDuring the experiment, use a thermometer to closely observe the surface temperature of the capacitor (the sensing contact of the thermometer can be wrapped around the capacitor with tape). Note that the initial current is very small and almost zero. When the temperature of the capacitor rises (about 35-40 ° C) The current is significantly increased. At this time, close observation should be made. When the current reaches or approaches 10A, the voltage should be lowered to ensure that the current is controlled within 10A. 6.5.3 Capacitor Safety ValveWithin 30 minutes after the start of the test, the capacitor safety valve should be opened. If the capacitor fuse is open, the power should be cut off immediately (the electrolytic capacitor of 350V 6800F will automatically open under the following conditions, the current is about 8A, the surface temperature is about 45-60 ° C.), If the current is close to 10A and the fuse is still 30 minutes later, If it is not turned on, this function is missing.Figure17. DC Digital Voltmeter6.6 Temperature TestThe capacity of a capacitor will change due to different ambient temperatures. In general, the capacity will increase as the temperature rises. The temperature test is to test the change of capacitance after equilibration under the set temperature. 6.6.1 High-Temperature Test(1) Connect two small wires to the lead-out terminal of the capacitor to be tested respectively, and test the capacity of the two lead terminals at normal temperature, and label them for record.(2) Put the capacitor into the high and low temperature alternating humidity and heat test box, and leave the leads outside the test box to test the capacitance.(3) Turn on the test box switch button, click "Temperature Setting" on the screen, set the temperature to 100 ° C, and click "Run" to start the test box.(4) Test the capacity again about 2 hours after the temperature reaches 100 ° C, and calculate the percentage change in capacity (the initial measurement of the difference). 6.6.2 Low-Temperature Test(1) Put the capacitor to be tested into the test box (be careful not to use capacitors that have been tested at high temperatures, except for special needs).(2) Turn on the test box switch button, click "temperature setting" on the screen, set the temperature to -25 ° C, and click "run".(3) Test the capacity again about 2 hours after the temperature reaches -25 ° C, and calculate the percentage change in capacity (the initial measurement of the difference). 6.6.3 PrecautionsThe test should pay close attention to whether there is any obvious change in the capacitor. If serious conditions such as cracking of the capacitor surface and opening of the safety valve occur, the test box should be stopped immediately. During the test, the operating procedures of the test box should be strictly followed, and the door of the test box should not be opened at will. At the end of the high temperature test, the capacitor can only be taken out after the temperature inside the test box has dropped to prevent accidents such as burns.Figure18. CapacitorsVII Considerations for Capacitor Testing(1) When measuring with a multimeter, select the gear according to the rated voltage of the capacitor. For example, the capacitor voltage commonly used in electronic equipment is low, only a few volts to dozens of volts. If the multimeter RX10k is used for measurement, the battery voltage in the meter is 12 ～ 22.5V, which is likely to cause capacitor breakdown. Therefore, the RXlk file should be used. measuring.(2) For the capacitor just removed from the line, be sure to discharge the capacitor before measurement to prevent the residual charge in the capacitor from being discharged to the meter and damage the meter.(3) For capacitors with high working voltage and large capacity, the capacitors should be sufficiently discharged, and the operator should have protective measures to prevent electric shocks during discharge. VIII One Question Related to Testing Capacitor8.1 QuestionWhat should we do when checking a capacitor with an ohm meter？8.2 AnswerTo remove the capacitor from the circuit. It's usually easy to remove a start or run capacitor – you simply unhook it from its harness and disconnect the wires. However, be careful to avoid touching the capacitor terminals. If the capacitor isn't dead, it might have a full charge, and if so, you could get a serious shock.  Ⅸ Frequently Asked Questions about How to Test a Capacitor1. How do you check if a capacitor is bad with a multimeter?Use the multimeter and read the voltage on the capacitor leads. The voltage should read near 9 volts. The voltage will discharge rapidly to 0V because the capacitor is discharging through the multimeter. If the capacitor will not retain that voltage, it is defective and should be replaced. 2. How do you test a capacitor at home?Set your voltmeter to read DC voltage (if it's capable of reading both AC and DC). Connect the voltmeter leads to the capacitor. Connect the positive(red) lead to the positive (longer) terminal and the negative (black) lead to the negative (shorter) terminal. Note the initial voltage reading. 3. How to test capacitor using multimeter? 4. Can you test capacitor on board?You just cannot test a bad capacitor inside or outside a circuit board by measuring its capacitance value with a capacitor meter or a multimeter. ... When the capacitor is outside the board, sometimes a bad capacitor may give you a proper capacitance value on the multimeter or capacitor meter. 5. What is the best capacitor tester?Best Capacitance Meter Review:Signstek MESR-100 V2 Auto Ranging in Circuit ESR LCR Meter CapacitorELIKE Digital Capacitor Tester 0.1pF to 20mFHoneytek A6013l Capacitor TesterMESR-100 circuit tester, KKMOON mesr-100 capacitor testerMultimeter Digital Capacitance Meter Capacitor Tester 0.1Pf to 2000uFExcelvan M6013 Digital Auto Ranging Capacitance Meter Capacitor TesterDigital Capacitance Meter Professional Capacitor 0.1Pf – 20000Uf 6. How do you test a capacitor with a cheap multimeter? 7. How many ohms should a capacitor have?1,000 ohmsSet it to its highest ohm (Ω) setting, at least 1 kΩ (1,000 ohms). At this setting, the meter generates a small current when you connect the meter leads to the capacitor terminals. 8. What is the capacitor symbol on a multimeter?Most digital multimeters use a symbol similar to –|(– to signify capacitance. Move the dial to that symbol. If several symbols share that spot on the dial, you may need to press a button to cycle between them until the capacitance symbol appears on the screen. 9. What if a capacitor reads high?It is reading as if there is a short circuit across it. If we read a very high resistance across the capacitor (several MΩ), this is a sign that the capacitor likely is defective as well. It is reading as if there is an open circuit across the capacitor. ... But not 0Ω or several MΩ. 10. What is the first step in testing a capacitor?The first and most simple is to inspect the capacitor. If it appears “blotted” or swelled, it is a safe bet that it is bad. It is good practice to go ahead and perform the following test even though it is swelled. Make a sketch of the wires connected to the capacitor and note the colors or numbers that identify them.