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CatalogⅠ What is a D Battery?Ⅱ How a D battery WorksⅢ Types of D Battery3.1 Non-Rechargeable D-Cell Batteries3.2 Rechargeable D-Cell BatteriesⅣ D Battery VS. AA BatteryⅤ D Battery VS. C Battery5.1 What Are The Similarities?5.2 What Are The Differences?Ⅵ D Batteries Buying GuideⅦ Frequently Asked Questions About D Battery Ⅰ What is a D Battery?A D battery (D cell or IEC R20) is a dry cell of standardized size. A D cell is cylindrical and features an electrical contact at either end, with a nub or bump on the positive end. D cells are commonly used in high current drain applications such as big flashlights, radio receivers and transmitters, and other devices that require a long operating period. D cells can be rechargeable or non-rechargeable. Its terminal voltage and capacity are determined by the chemistry of its cell. In 1898, the National Carbon Company introduced the first D cell. D cells were popularly recognized as flashlight batteries until smaller cells became more common. The D cell battery is a huge storage container for chemicals that generate electrons inside. The battery has two opposite terminals at each end of the casing, which are often referred to as the positive (+) and negative (-) terminals. Carbon and zinc plates float and rotate inside the battery's shell in an acidic solution such as sulphuric acid, manganese dioxide, or hydrochloric acid. The acidic paste works as an electrolyte, causing a chemical reaction that generates electrons. These electrons accumulate at the negative battery terminal of the carbon because they have nowhere else to go and no reactions are taking place.  Ⅱ How a D battery WorksA accumulation of electrons at the battery's negative carbon terminal will result in the battery powering your gadget. The battery's positive terminal includes zinc, which naturally attracts electrons. If you attached a wire from the positive connection to the negative terminal the battery's energy would soon dissipate as electrons raced along the wire to the zinc plate at the positive terminal. When you place a battery into an electronic gadget, each terminal is connected to a wire.  The negative terminal then establishes a conduit for electrons to pass through the electrical device's wiring. This powers the equipment as it travels until the electrons arrive at the positive terminal at the end of their journey. This flow of electrons is what causes the wheels of your toy truck to spin or your radio to play music. This effectively converts the gadget into a circuit for electron flow. Batteries are not limitless, and this is due to the loss of zinc present at the battery's positive end. D batteries typically have a lifespan of 60 times that of an AA battery. The capacity of the battery and the drain applied to it by the device it is powering determine the battery's life. A typical D battery has a capacity (mAh) of 12000 and a drain (mA) of 200. Each cycle of electrons travelling through the battery wears away at the zinc plate over time. When the zinc plate is completely depleted, the battery is dead and must be replaced. Rechargeable batteries are another alternative that can save you money over time versus buying new batteries every time you need to replace them. Ⅲ Types of D Battery Primary batteries are available in Alkaline, Lithium, Zinc Carbon, and Lithium Iron Disulfide varieties (LiFeS2). Zinc Carbon and LiFeS2 are the only two chemistries that are completely disposable cells. As in the case of  RAMs and Lithium-ion or rechargeable Lithium, both Alkaline and Lithium offer rechargeable variations. The rechargeable batteries Nickel Metal Hydride (NiMH) and Nickel Cadmium (NiCad) have nominal voltages and other characteristics that are predetermined by their individual battery chemistry. D-cell batteries have dimensions of 34.2 61.5 mm (1.35 2.42 inches) and are one of the largest cylindrical batteries in general usage. F-cells (33.0 x 91.0 mm) are larger than D-cells but are not as prevalent. The chemistry of the battery has a large impact on its capacity, voltage, output current, and other characteristics. The following comparison table lists the most frequent chemistries: ChemistryTypical LabelRechargeableTypical Capacity (Ah)Nominal Voltage (V)Zinc-CarbonR20, 13DNo6 to 81.5AlkalineLR20, 13ANo (Mostly No)10 to 181.5NiCdKR20Yes2 to 61.2NiMHHR20, B006Yes8 to 121.2Li-SOCl2ER 34615No18 to 193.6Li-FeS2-No18 to 241.8 (1.5)Lithium-Yes4 to 81.5 (built-in DC-DC converter) 3.1 Non-Rechargeable D-Cell BatteriesNon-rechargeable D-cells based on the iron disulfide (Li-FeS2) chemistry are not yet widely used, at least as D-cells, despite offering a nominal voltage of 1.5 volts (up to 1.8 open-circuit voltage), ultra-long storage time (10-20 years), and higher capacity, particularly in high-drain applications. Non-rechargeable D-cell chemistries include zinc-carbon, alkaline, and Lithium-Thionyl Chloride (Li-SOCl2) batteries, whereas NiOOH (non-rechargeable chemistry) and NiZn (rechargeable chemistry) are uncommon in this battery size. Zinc-Carbon D-cells typically have a capacity of 6-8 Ah (6000-8000 mAh) with a nominal voltage of 1.5 volts. Zinc-carbon D-cells are the most traditional type of D-cell, with a nominal voltage of 1.5V that is still practically required for D-cell batteries. Zinc-carbon D-cells have a shelf life of 3-5 years and are reasonably priced and dependable. However, if they are not properly preserved, their shelf life can be reduced to 1-2 years. Furthermore, due to their chemistry, they may leak easily after a while. Alkaline batteries have significant advantages over zinc-carbon batteries. Alkaline D-cell batteries are slightly more expensive than zinc-carbon batteries, but they have a much larger capacity (12-18 Ah vs 6-8 Ah), a similar nominal voltage of 1.5 volts, and a shelf life of 5-10 years or more. It is important to note that the actual capacity of these batteries is very dependent on the discharge current - some battery brands advertise 20+ Ah capacity for their D-cells, but such capacities are only attained when the batteries are drained at very low currents (15-30 mAh). The most common type of D-cell battery is an alkaline D-cell. Lithium-Thionyl Chloride (Li-SOCL2) batteries are a type of D-cell battery that is very specialized. These batteries have a 3.6V nominal voltage and are incompatible with 1.5V D-cell batteries. They also have a very large capacity of 18-19Ah and a very long shelf life of 20+ years. However, Lithium-Thionyl Chloride (Li-SOCl2) D-cell batteries are incapable of providing higher currents. - The normal maximum continuous discharge current of Lithium-Thionyl Chloride (Li-SOCl2) D-cell batteries is 50-150 mAh, with a pulse current of 200-300 mAh. As a result, Li-SOCl2 D-cell batteries are utilized in electronics as memory backup batteries, CMOS batteries, and other similar applications. Li-SOCl2 D-cell batteries are available in a variety of configurations, including traditional D-cell batteries, batteries with soldering tabs, and batteries with pre-soldered wires and connectors. 3.2 Rechargeable D-Cell BatteriesNiCd, NiMH, and different lithium-ion batteries are the most common rechargeable D-cell batteries. Due to the presence of cadmium, a heavy metal that is a severe pollutant, nickel-cadmium (NiCd) D-cell batteries are rarely used. NiCd batteries have a relatively high self-discharge rate, a nominal voltage of 1.2 volts, and a typical capacity of 2-6 Ah. When properly maintained and charged with intelligent chargers that monitor the battery's status, NiCd batteries may withstand hundreds of charging-discharging cycles. However, NiCd batteries are noted for their ability to generate enormous currents, with some NiCd D-cell batteries capable of providing 50+ Amps. Nickel Metal Hydride (NiMH) D-cell batteries have a comparable output voltage of 1.2 volts as NiCd batteries, but they have a bigger capacity (8-12 Ah), don't contain heavy metals like cadmium or mercury, have a significantly lower self-discharge rate, and can endure up to 1000-1200 charge/discharge cycles. Some NiMH batteries are geared for high-drain applications and have lower capacity, whilst others are optimized for low-drain applications and have larger capacity. The average capacity of a NiMH D-cell is roughly 10 Ah. Modern NiMH batteries surpass NiCd batteries in practically every manner, making them the favored battery chemistry for rechargeable D-cells - and not only D-cells. Lithium D-cell batteries have an internal voltage of 3.2-3.7 volts, depending on the lithium battery chemistry, but this voltage is reduced to 1.5 volts using DC-DC converters built into the batteries' built-in Battery Management Systems (BMS), making them backward compatible with non-rechargeable zinc-carbon and alkaline D-cell batteries. These batteries' effective capacities are often in the 3-6Ah range. Lithium 1.5V D-cells are recharged using micro-USB charging cables and any available USB charging connection, taking approximately 3-6 hours to fully recharge. Because of the internal lithium batteries, lithium 1.5V D-cells can be charged and discharged 1000-2000 times. Note: Lithium rechargeable 3.2-3.7 volts D-cell batteries are either not available or are extremely rare. However, they will NOT be compatible with "1.5V only" apps when they come. Ⅳ D Battery VS. AA Battery AA batteries have physical dimensions of (D x H) 14.5 x 50.5 mm and are significantly less in volume than D-cell batteries (34.2 x 61.5 mm). As a result, AA cells have a far lower capacity than D-cell batteries; for example, alkaline AA batteries have a nominal capacity of 1.8-2.7Ah, whereas alkaline D-cells have a nominal capacity of 10-18Ah. Similarly, D-cells can deliver far higher currents than AA batteries without causing any damage to the batteries. However, some manufactures provide AA-to-D battery adapters, which allow the user to replace the D battery with one, two, or three AA batteries connected in parallel. Note: When putting AA batteries in such adapters, always use the same AA battery model from the same manufacturer, preferably from the same batch, to avoid battery imbalances. Ⅴ D Battery VS. C Battery   5.1 What Are The Similarities?The voltage is the most striking similarity between C and D batteries. Both alkaline batteries are 1.5 volts. The rechargeable versions of these batteries have a voltage of 1.2 volts. The only thing these two types of batteries have in common is this. 5.2 What Are The Differences?Battery SizeC batteries measure 50mm x 26.2mm.D size batteries measure 61.5mm x 33.2mm. Because of the size difference, it is critical to ensure that you choose the correct ones when purchasing new batteries. If not, you may need to modify them to fit within the battery compartment or pay additional money to get the exact size. Physical SizeLarger physical size for higher capacity D batteries are larger than C batteries in order to store more energy. As a result, they will be more durable. Furthermore, these batteries have larger electrodes, allowing them to deliver much higher current levels. Larger capacity batteries can supply a higher level of current concurrently and for longer periods of time. In terms of mAh, the C battery has a capacity of up to 8,000 mAh, while the D battery has a capacity of up to 17,000 mAh. Larger battery size for larger electronic devicesBecause of the size difference, these batteries will be employed in a variety of equipment. C cell batteries are often used in devices that don't require a lot of power, such as small flashlights, toys, and some musical instruments. D cell batteries, on the other hand, are used in devices that require greater power, such as medium/large flashlights, radios, and alarm systems. In addition, any other gadgets that require batteries with a long run life. These batteries are twice as large as C batteries. Can You Use C Batteries In Place Of D Ones?Yes, C batteries can be used in place of D batteries. However, you must ensure that they are of the same voltage. So, if the D batteries in the device are 1.5 volts, you must replace them with 1.5 volt C batteries. What will happen when replacing D battery with C battery?The differences in voltage and capacity of batteries impact how successfully they produce power. In a flashlight, for example, the voltage of the battery determines how strong the light it emits. The current, on the other hand, regulates how long a flashlight will glow. As a result, when the flashlight is turned on, batteries with a greater voltage will create a significantly brighter light. Higher amp-hour batteries will produce more light for a longer period of time. As a result, using a C cell instead of a D battery makes no change in the brightness of the light. However, because the number of amps in a C battery is fewer, you'll need to replace the batteries more frequently because they have a considerably shorter running time. How To Use A C Battery  In A D-Size Spacer?Another factor to consider is the amount of space available for the battery. Remember that C batteries are somewhat shorter than D batteries, so you'll need to create an adaptor to keep them in position. To use a C battery in a D-size spacer, just insert two quarters, one at each end of the battery, into the gap where the battery sits. Can You Place A D-Size Battery Into One Of The C-Spacers Or AA-Spacers?Unfortunately, D-size batteries cannot be used in devices that require C or AA-spacers. As previously stated, these batteries are significantly larger and will not fit into the allotted area. TV remote controls, for example, are frequently powered by C or AA batteries. They avoid using D size batteries since the remote control would have to be larger, making it more difficult to use. Plus, devices like these don't use as much energy to operate. What To Consider Before Buying C, D Batteries?When shopping for such batteries, the capacity is the most important factor to consider. Choose batteries with a greater mAh rating if possible, as these will have a longer run time. It is also critical to avoid purchasing low-cost generic models in stores, particularly rechargeable D-size models. These typically have a capacity of roughly 2,500 mAh, which is insufficient. You'll probably spend more time charging them than utilizing them in the devices for which they were designed. Instead, go online and get such rechargeable batteries, as there are plenty that can give you with 9,000 mAh. It may cost more, but it will be worth it in the long run. Ⅵ D Batteries Buying Guide  The Most Important Features to Consider 1.Shelf Life and Work in Extreme TemperaturesEach battery has a minimum suggested shelf life of five years. Many of our recommendations have a 10-year shelf life. The greater the shelf life, the longer they are functional, regardless of environmental exposure. Some batteries, such as the Duracell DC1300, can also work in temperatures as low as -4 degrees Fahrenheit and as high as 129 degrees Fahrenheit, increasing reliability in searing hot vehicle trunks and outdoor emergencies. 2.Number per PackThe more batteries there are in a pack, the longer you can keep a single gadget charged over its service life. 3.Power or mAhmAh stands for milliamp hours. The greater the number, the longer your devices will remain powered. It is important to note that the longevity of your device is determined by its power draw. Look for D batteries that have a minimum capacity of 10,000 mAh. If your device draws 100mA of current, the battery will last approximately 100 hours. 4.Rechargeable vs Single UseWhen compared to single-use batteries, rechargeable batteries offer significant cost savings. The EBL Rechargeable D batteries have a lifespan of up to 1,200 cycles @ 10,000 mAh, equating to cents each charge. It's worth noting that rechargeable batteries often have a lower mAh rating than single-use batteries, so you're trading power for convenience. However, if you are powering low-power gadgets, this should be inconsequential. Ⅶ Frequently Asked Questions  About D Battery1. Are all D batteries the same?They differ in amperage, which means they have varied total amounts  of energy (which is also why they are different sizes). D batteries are commonly used in high current drain applications, i.e. items that demand a long run time. 2. What is equivalent to D battery?Electrically, one AA battery might accomplish the job because it has the same voltage as a D battery. It was, however, easier to combine four AA batteries into one to imitate the size of a D cell and effectively replace it. 3. Can you recharge D batteries?Alkaline batteries can, in fact, be recharged. However, it is not seen as cost effective and carries some dangers. When a battery is recharged, gas is produced within the battery. 4. Is D4 same as D batteries?The D4 is identical to the D3, but has only one layer of shielding and a 50 impedance. A D battery (also known as a D cell or IEC R20) is a type of dry cell. A D cell is cylindrical and features an electrical contact at either end, with a nub or bump on the positive end. D cells can be rechargeable or non-rechargeable. 5. Do D batteries have more power?Some electrical gadgets require a lot of current but not a lot of voltage to function. This is when the size of the battery comes into play. The D size battery has a higher current rating than the C, AA, and AAA size batteries. 6. How can you tell if an a D battery is good?Drop each battery from a couple of inches up (with the flat, negative end down). If the battery is fully charged, it should create a strong thud and most likely remain upright. If the battery dies, it will quickly bounce and tumble over. 7. How are D cell batteries made?The battery shell is made of steel and houses the electrodes, an anode (the negative terminal) and a cathode (the positive terminal). The cathode is built up of silvery matte rings of manganese dioxide, graphite, and electrolyte. The anode is the zinc paste that is contained within the separator. 8. Whats the difference between D4 and D8?Here are the D4's advantages, in my opinion: Smaller size, lighter weight, and fewer batteries to purchase and charge. The advantage of D8 is that it is much brighter. The D4 is powered by two 5.8 watt lamps, whereas the D8 is powered by two 14 watt lamps. According to UK, the D4 and D8 have a battery life of 7-10 hours. 9. How long do D batteries last in a fan?While the four D batteries required aren't included, this fan can run for up to 214 hours on a single set, so you won't need to replace them very frequently. With a maximum noise level of 50 decibels, it's also an excellent choice for people looking for a quieter fan. 10. Why are D cell batteries so big?In general, the larger the battery, the greater its potential for energy storage. So, while both the big and small batteries are rated at 1.5V, the big battery stores more energy and has a longer battery life. 

What is the pcb?What is the pcb assembly?Video about the pcb assemblyWhat are the differences between the PCB and PCBA?Types of pcb assemblySMT assemblyBGA assemblyThrough-hole assemblyMixed assemblyRigid-flex printed circuit board assemblyConclusion of SMT assembly VS BGA assembly VS Through-hole assembly VS Mixed assembly VS Rigid-Flex PCBAFrequently Asked Questions – FAQsWhat is the pcb?The fundamental component of the majority of contemporary electronic gadgets are printed circuit boards, or PCBs. Printed circuit boards are the base on which all other electronic components are assembled, ranging from simple single-layered boards used in your garage door opener to the six-layer board in your smart watch to the 60-layer, extremely high density and high-speed circuit boards used in super computers and servers. The PCB serves as a mounting surface for semiconductors, connections, resistors, diodes, capacitors, and radio equipment, all of which "speak" to one another.PCBs are the best choice for these applications because of their mechanical and electrical qualities. Roughly 90% of the PCBs produced today are rigid, making them the most common type of PCB in the world. Some PCBs are flexible, allowing the circuits to be stretched and folded into shape. Other times, flexible circuits are employed in applications where they can withstand hundreds of thousands of bend cycles without failing. Ten percent or so of the market is made up of these flexible PCBs. A tiny subset of these kinds of circuits are referred to as rigid flex circuits, which have firm parts of the board that are perfect for mounting and connecting components and flexible parts that offer the benefits of flexible circuits that were previously mentioned.What is pcb What is the pcb assembly?PCBA  = assembly of PCB. A surface encapsulation procedure is used to integrate various electrical components on the circuit board. The box assembly comes next, which joins the finished product's outer case and assembled PCB. In other words, the PCB bare board travels via the SMT top section before traveling through the full DIP plug-in process, also known as PCBA. In contrast to PCB'A, which adds a slant point, which is the norm in Europe and America, this approach is widely employed in the nation. PCBA stands for printed circuit board assembly. If a market is viable, mass production for new electronic designs would typically follow prototype pcb assembly (Sample PCBA) to verify designs.PCB Assembly Video about the pcb assemblyVideo Description: This is a great explanation of the printed circuit board (PCB) and electronics manufacturing process in the context of IOT. What are the differences between the PCB and PCBA?The terms "bare circuit board" (PCB) and "circuit board plug-in assembly" (PCBA) both relate to the SMT technique. A finished board is one, and a naked board is the other. According to the number of signal layers, PCB (Printed Circuit Board), made of epoxy glass resin material, is divided into 4, 6, and 8 layers. The most typical layer counts are 4 and 6. The bare board has chip components like chips attached to it. PCBA can be thought of as a finished circuit board, and it can only be produced if the circuit board's manufacturing process is concluded. PCBA=Printed Circuit Board +Assembly. Types of pcb assemblySMT assemblyBGA assemblyThrough-hole assemblyMixed assemblyRigid-Flex PCBA SMT assemblyWhat is the SMT assembly?SMT, or surface mount technology, is its full name. SMT is a technique for attaching parts or components to circuit boards. SMT has replaced other methods in PCB assembly due to its superior results and increased efficiency. Through-hole assembly was mostly utilized in the past by PCB producers to add components. But SMT has introduced welding technology to replace the previous assembling technique. And all electronic businesses, including those in computers, telephones, smartphones, home appliances, etc., use PCBs made using the SMT assembly process. Printing solder paste, mounting components, reflow soldering, AOI, or AXI are all components of the basic SMT assembly process.SMT Assembly The advantages of SMT assemblySmall size and lightweightThe total size and weight of the PCBs are reduced by directly attaching the components to the board using SMT technology. This assembly process enables us to fit more components into a small area, resulting in smaller designs and improved performance. High reliabilityAfter the prototype has been validated, the entire SMT assembly process is almost fully automated using precise equipment, which reduces the possibility of human error. SMT technology ensures the consistency and dependability of the PCBs because of automation. Cost-savingSMT assembly is often carried out using automated equipment. Even though the machines' input costs are expensive, the automatic machines assist in reducing manual steps throughout SMT operations, which considerably increases production efficiency and, over time, lowers labor costs. Additionally, through-hole assembly requires less materials, which lowers the cost. SMT assembly capabilities of PCBGOGOA fully automated SMT workshop for bulk production is owned by PCBGOGO. We also offer manual welding services for difficult items, prototyping, and small quantity orders. For PCB assembly, we have FR4 board, aluminum board, flexible board, and rigid-flex board options. Other assembly types, besides SMT assembly, include BGA assembly, through-hole assembly, mixed assembly, and kit assembly. The following files should be included with your SMT orders: a Gerber file (used for PCB fabrication), a BOM list, a CPL list, or a PNP list (pick and place). BGA assemblyWhat is BGA?An integrated circuit is packaged using a surface-mount device called a ball grid array (BGA), sometimes known as a chip carrier. Devices like microprocessors are permanently mounted using BGA packaging. A BGA can offer more connector pins than a dual in-line or flat package can accommodate. Instead of simply the edge, the entire bottom surface of the gadget can be used. Additionally, compared to a perimeter-only type, the traces connecting the package's leads to the wires or balls that connect the die to the package are typically shorter, improving performance at high speeds.BGA Assembly The advantages of BGA assemblyHigher-density circuitsThrough-hole circuits got more densely populated, making it practically impossible to solder them precisely without crossover or short-circuits. Heat conductionBGA circuits minimize overheating issues by facilitating significantly easier heat transfer from the integrated circuit externally. Lower inductanceThe likelihood of interference issues in a BGA circuit is considerably reduced because each solder ball typically only measures a few millimeters in size.  Through-hole assemblyWhat is a through-hole assembly?Electronic circuits are created using the through-hole assembly technique, in which the components are inserted using leads. It describes the installation procedure in which the leads are inserted into the pre-drilled holes and the components are soldered to the board using either wave soldering or manual soldering.PCB design evolved over time from single-sided to double-sided, and finally to multi-layer boards. It is challenging to adapt through-hole assembly to the needs of contemporary electronics. In today's PCB production, SMT technology has essentially taken the place of through-hole construction. However, some applications, including those for electrolytic capacitors, connections, and big transformers, still require through-hole installation.Through-hole AssemblyThe advantages and disadvantages of Through-hole assemblyHigh reliabilityAs opposed to SMT components, which are simply soldered on the PCB's surface, through-hole assemblies require leads that are inserted into the holes to secure the components to the board, which results in higher environmental stress. As a result, through-hole assembly provides a stronger physical connection, making it the preferred method for the aerospace sector and the military, both of which have high dependability requirements. Easy for manual operationBecause replacing or moving through-hole components is simpler, this assembly technique is frequently utilized in applications that call for PCB testing and PCB prototyping. Higher durabilityIndustrial machinery and equipment frequently use through-hole components due to their strong heat resistance and high stress tolerance. Through-hole LEDs are used in the LED lights on enormous billboards because they are strong and bright. Lower manufacturing efficiencyDue to the extra step of drilling and hold the components using leads, through-hole assembly is time-consuming, which causes higher costs and lower production efficiency. Limited PCB designDrilled holes must penetrate all layers of the board in through-hole assembly, which makes multi-layer PCBs unsuitable since it makes layout design and PCB manufacturing more challenging. Additionally, the board would be larger overall than SMT PCBs, which would limit its range of applications. Mixed assemblyWhat is the mixed assembly?Although surface mount technology has taken over as the primary mounting technique in PCB manufacture, some components are still incompatible with SMT assembly. The same board must then be used for SMT assembly and THT assembly. A mixed assembly is what is referred to as a blend of assembly technologies without the usage of solder paste during production.The majority of the components are welded in surface mount configuration on the board, although mixed PCB assembly is required for some specific components that are not available in the SMT process.Mixed AssemblyThe advantages of Mixed assemblyThrough-Hole, SMT, and BGA components are housed on the PCB in a mixed assembly.SMT (Surface Mount Technology) or single- or double-sided mixed technology for PCB assembly BGAs have one or two sides, as well as micro-BGA.100% X-ray inspection during installation and rework.Small-quantity PCB board components include all varieties of BGAs, QFNs, CSPs, 0201, 01005, POP, and Pressfit Components.SMT and through-hole polarized capacitors are examples of part polarity capacitors.Rework capabilities include the ability to remove and replace BGAs and MBGAs, as well as having experience with ceramic and plastic BGAs. Rigid-flex printed circuit board assemblyWhat is Rigid-Flex PCBA?Printed circuit boards that combine rigid and flexible board technologies are known as rigid-flex boards. Depending on the application's design, the majority of rigid flex boards are made up of many layers of flexible circuit substrates that are outwardly or internally attached to one or more rigid boards. The flexible substrates are typically formed into the flexed curve during manufacturing or installation and are intended to be in a constant state of flexibility.Rigid-Flex PCBAThe advantages of Rigid-Flex PCBABy using 3D, space requirements can be reduced.The size of the board and the weight of the entire system can be decreased by doing away with the requirement for connectors and cables between the various rigid pieces.There is frequently a lower part count when space is maximized.Lower solder junctions guarantee more reliable connections.Assembling rigid boards is easier than handling flexible boards.PCB assembly procedures that are simpler.Simple modular interfaces to the system environment are provided by integrated ZIF contacts.Simpler test conditions are used. a thorough test is conducted before installation is possible.Rigid-Flex boards greatly lower the cost of logistics and assembly.It is feasible to make mechanical designs more sophisticated, which raises the degree of freedom for ideal housing solutions. Conclusion of SMT assembly VS BGA assembly VS Through-hole assembly VS Mixed assembly VS Rigid-Flex PCBA Which one is better in PCBA: SMT, BGA, or Through-hole?Through-hole technology might be the most effective for low-volume PCB fabrication (like prototyping). For components that must withstand high stress, through-hole is frequently viewed as the superior option since wire leads provide a solid link. The preferred mounting method for front connectors, where USB cables and cords will be plugged in, is frequently via hole. However, drilling holes costs more and requires soldering on both sides of the PCB, which extends the production cycle. On multi-layer boards, through hole connectors can reduce the available routing space.Multiple advanced functions, effective performance, and enhanced speed are required for modern electronic gadgets, all in a smaller device. Even with more electronic components, the assembly still needs to be thinner. BGA packages are the best choice for these needs. For instance, BGAs are typically used in the manufacturing of ICs having more than 200 I/O connections. Surface Mount is a superior option when production volumes are high since SMD components take up less space, resulting in a more compact, component-dense circuit board. SMT is a more dependable method than manual assembly using through-hole technology because SMDs are amenable to automation utilizing pick-and-place robotic machines—no drilling is necessary. The industry standard method for back connectors is SMT. SMT does have some drawbacks, too. For example, it is not recommended for connecting high-stress components, and it necessitates an initial investment in pricey technology for mass production.Overall, SMT is more cost-effective and time-efficient. The comparison between SMT assembly and THT assemblyFirst, SMT components are fully automated and welded onto the board using a reflow machine. While wave-soldered and hand-soldered techniques are both traditional approaches in the THT assembly process, THT assembly requires pre-drilling holes in the board and employing leads to link the components and circuits.Second, only wave soldering is permitted for PCBs with through-hole components; reflow or wave soldering are not permitted for PCBs with surface mount devices (SMDs). Therefore, if both SMT components and THT components are used on the board, there are extra stages in the assembly process. Typically, SMT is carried out first, followed by THT assembly.Thirdly, SMT assembly can be completed quickly and accurately thanks to advanced and precise machinery. SMT is more suited to high-density and tiny size PCB applications due to its ability to precisely insert thin and small components on the board. Additionally, THT is favoured by components with high requirements for dependability and huge size since it offers more durable connections than SMT components.SMT assemblies have a number of advantages, including high productivity, high precision, light weight, and low cost. SMT is quicker and more cost-effective for mass production. THT assemblies are often very dependable, have a high stress tolerance, are heavier, and cost more. THT is the ideal assembly technique for prototype and small-scale PCB production. The comparison between SMT assembly and Rigid-Flex PCBAElectrical components are put directly onto the surface of a printed circuit board using surface-mount technology (SMT) (PCB). Because SMT components can have smaller leads or no leads at all, they are often smaller than their through-hole counterparts.Photolithographic technology is used to create flexible printed circuits (FPC). Stiff flex printed circuit boards are circuit boards that combine rigid and flexible board technology. Depending on the application's design, the majority of rigid flex boards are made up of many layers of flexible circuit substrates that are outwardly or internally attached to one or more rigid boards.All in all, SMT is more cost-effective and time-efficient and Rigid-Flex PCBA is time-consuming and expansive. Frequently Asked Questions – FAQsWhat is PCB board?Copper conductors are used to make electrical connections between components on a printed circuit board (PCB), which is an electronic assembly. Electronic components are mechanically supported by printed circuit boards, allowing a device to be housed in an enclosure. What are the differences between the rigid pcb and flexible pcb?From their names, it may be deduced that stiff PCBs and flex PCBs differ most significantly. Flex PCBs can be bent or otherwise shaped to fit inside the designated system while rigid PCBs cannot be bent or otherwise shaped. When properly engineered, flexible circuits can be repeatedly stretched for hundreds of thousands of cycles without breaking. Flex boards are more expensive on average, but they are necessary for applications with constrained space requirements, such as consumer electronics, medical devices, space applications, and automotive applications. The affordability of rigid circuit boards is a major factor in their popularity. Because rigid circuit boards take up less space, manufacturers can save a lot on traditional electronics, especially consumer electronics. What does PCB assembly mean?A printed wiring board (PWB), on the other hand, is a board that is devoid of components and is used in electronics that do not require complicated functionality. A printed circuit board (PCB) is a completely constructed board that has all the circuitry required to go into an electronic device. What is PCB SMT assembly?The technique of soldering electronic components to a printed circuit board (PCB) is known as SMT assembly technology. Small amounts of molten solder paste are utilized in this procedure to join the component leads to pads on the PCB surface. What is PCB BGA assembly?Ball grid array, sometimes known as BGA, is a type of packaging used to mount components with hundreds of pins, such as microprocessors. It also goes by the name Ball Grid Array. BGA assembly is the process of directly mounting the BGA packages or integrated circuits (ICs) onto the BGA board and soldering them in place.

What is a resistor? In short, resistors are electronic components which have a specific, never-changing electrical resistance. The resistor's resistance limits the flow of electrons through a circuit. So in this article today, we will have a detailed discussion on resistors, which will present you as much as information about resistor as possible.I What is a Resistor?1.1 Brief IntroductionResistors are passive electrical components that limit electric current. This video explains in an easy way the most basic background to help you understand resistors and use them.A resistor refers to a two-terminal electronic element made of resistor material with a certain structure that can limit the current passing through the circuit. It is the most widely used component in electronic circuits, which usually form different series according to its power and resistance values. Its function in circuits is to regulate and stabilize current and voltage, that is,  used as shunt and voltage divider, or circuit matching load. According to the circuit requirements, it can also be used for negative feedback or positive feedback of amplifying circuit, voltage-current conversion, voltage or current protecting element when existing input overload. With the capacitor, it can form an RC circuit, which can be used as oscillation, filter, bypass, differential, Integral and time constant elements, etc. Those whose resistance values cannot be changed are called fixed resistors, and those with variable resistance values are called potentiometers or variable resistors. Some special resistors, such as thermistors, varistors, and sensitive elements, have a nonlinear relationship between voltage and current.1.2 Resistor and ResistanceThe resistor is a current limiting element in daily life. Resistance is a physical quantity describing the conductivity of a conductor, represented by R. Resistance is defined by the ratio of the voltage U at the two ends of the conductor and the current I passing through the conductor, that is, R=V/I. When the resistor is connected to the circuit, the resistor's resistance is fixed by two pins, which can limit the current to flow through the branch of the resistor. The resistance that cannot be changed is called a fixed resistor. In addition, a variable resistance is called a potentiometer or a variable resistor. The ideal resistor is linear, that is, the instantaneous current of the resistor is positive to the applied instantaneous voltage, for example, the variable-voltage resistor is used as a voltage divider. On a bare resistor, there are one or two removable metal contacts, and the contact position determines the resistance between any end of the resistor and the contact.  The terminal voltage and current have a definite function relation, and the two-terminal device which embodies the conversion of electric energy into other forms, represented by the letter R, and its unit is Ω. Devices such as light bulbs, heating wires, resistors, and so on can be expressed as resistor elements.The resistance value of the resistor is generally related to temperature, material, component length, and cross-section area. The physical quantity of measuring resistance affected by the temperature is the temperature coefficient, which is defined as the percentage of resistance value changing when the temperature rises 1℃. The main physical characteristic of resistors is transforming the electricity into heat energy, also the resistor can be said to be an energy dissipation element because the internal energy will be generated when current flows through it. Resistors usually act as a divider and shunt in a circuit. And for signals, both AC and DC signals can pass through resistors.In physics, resistance is a figure to indicate the magnitude of a conductor's hindrance to current. The greater the resistance of a conductor, the greater the resistance of the conductor to the current. Generally, different conductors have different resistances, in other words, resistance is a characteristic of the conductor itself. The resistance element is a kind of energy dissipation element which hinders the current. The stuff under the action of matter called resistive substance because of its blocking effect on the current. The resistor will lead to the change of the electron flux. When the voltage at both ends of the conductor is fixed, the larger the resistance, the smaller the current passing through, on the other hand, the smaller the resistance, the greater the current passing through. 1.3 Resistor BasicsThe resistor consists of three parts of a resistor body, a framework, and a lead-out end (the resistor body of the solid-core resistor is integrated with the framework), and the resistor body plays an important part in this electronic component. For a resistor body with a uniform cross-section, the resistance value is calculated by the following formula: ρ is the electrical resistivity (ohm-cm), L is the length (cm) of the resistor, and A is the cross-sectional area of the resistor (square centimeter).R=ρ× L/AThe thickness of the thin film resistor is very small and difficult to measure accurately, and ρ varies with the thickness values, so the constant related to the film material is regarded as the film resistance. In fact, it is the resistance of the square film, so it is also known as the square resistance. For homogeneous films, W is the width of the film (cm), in general, Rs should be in a limited range because large Rs will affect the stability of resistor performance. Therefore the cylindrical resistor is notched and the planar resistor uses the etching method of a detour to extend the range of resistance and to fine-tune the resistance.R=Rs×L/WThe volt-ampere characteristic is a graph that represents the relationship between the voltage and the current of the resistor terminal. When the voltage-current is proportional (representing a straight line), it is called a linear resistor, otherwise referred to as a non-linear resistor.The vertical coordinates of this diagram are current I and the transverse coordinates are voltage U. This graph is also called the current-voltage curve, more often is referred to as the volt-ampere characteristics curve. As we can see, the blue curve is a straight line passing through the origin, and its resistance does not change with the change of voltage and current, in fact, elements that satisfy this volt-ampere characteristic curve are called linear elements. On the other hand, for the red curve, we can see that it is a curve, its resistance value changes with the change of voltage and current.The main parameters used to characterize the resistance have nominal resistance, allowable deviation, rated power, load characteristic, resistor temperature coefficient, and so on.1.4 Resistor Operation TheoryOhm's lawThe behavior of an ideal resistor is dictated by the relationship specified by Ohm's law:V=I ∙ ROhm's law states that the voltage (V) across a resistor is proportional to the current (I), where the constant of proportionality is the resistance (R). For example, if a 300-ohm resistor is attached across the terminals of a 12-volt battery, then a current of 12/300 = 0.04 amperes flows through that resistor.Practical resistors also have some inductance and capacitance which affect the relation between voltage and current in alternating current circuits.In addition, linear or ohmic resistance meets Ohm's law, but nonlinear resistance does not satisfy Ohm's law.The nominal resistance is the design resistance of the sign on the resistor with a digital or color code. The units are Ω, KΩ, and MΩ. Resistance values are written according to standardized priority series, which correspond to allowable deviations.The electrical resistance of a resistor is measured in ohms. The symbol for an ohm is the greek capital-omega: Ω. The ohm (symbol: Ω) is the SI unit of electrical resistance, named after Georg Simon Ohm. An ohm is equivalent to a volt per ampere. Since resistors are specified and manufactured over a very large range of values, the derived units of milliohm (1 mΩ = 10−3 Ω), kilohm (1 kΩ = 103 Ω), and megohm (1 MΩ = 106 Ω) are also in common usage. For example, a 4,700Ω resistor is equivalent to a 4.7kΩ resistor, and a 5,600,000Ω resistor can be written as 5,600kΩ or (more commonly as) 5.6MΩ. 1.5 Resistor Electronic SymbolsNotation1Ω= 1 Ohms1 KΩ= 1 Kilo Ohms1 MΩ= 1 Mega Ohms1 GΩ= 1 Giga OhmsWhen the value can be expressed without a prefix (that is, multiplicator 1), an "R" is used instead of the decimal separator. For example, 1R3 indicates 1.3Ω, and 15R indicates 15Ω.Marking method for Resistance and Tolerance of Resistors：① Direct Scaling MethodThe resistance and error of the resistor are directly printed on the resistor by numbers and letters (no error is indicated as the tolerance ±20%). There are also manufacturers who use customary marking methods, such as:3Ω3Ⅰis represent the resistance 3.3Ω, tolerance is ±5%1 K 8 represents the resistance 1.8 KΩ, tolerance is ±20%5 M 1Ⅱis represent the resistance 5.1 MΩ, tolerance is ±10% ② Resistor Color Bands/CodesThis Physics video tutorial is explaining the fundamentals of color code for four colour bands in a carbon resistor.The color bands are coated on the resistor to indicate the nominal value of the resistor and the allowable tolerance. The corresponding values of various colors and the recognition rules of the color bands/codes of the reading principle of the fixed resistor are shown in the following figure.Four-band ResistorsIn the standard four-band resistors, the first two bands indicate the two most significant digits of the resistor’s value. The third band is a weight value, which multiplies the two significant digits by a power of ten.The final band indicates the tolerance of the resistor. The tolerance explains how much more or less the actual resistance of the resistor can be compared to what its nominal value is. No resistor is made to perfection, and different manufacturing processes will result in better or worse tolerances. For example, a 1kΩ resistor with 5% tolerance could actually be anywhere between 0.95kΩ and 1.05kΩ.Example: red-orange black gold=23*10^0=23Ω(±5%)Five-band and six-band ResistorsFive band resistors have a third significant digit band between the first two bands and the multiplier band. Five band resistors also have a wider range of tolerances available.Six band resistors are basically five band resistors with an additional band at the end that indicates the temperature coefficient. This indicates the expected change in resistor value as the temperature changes in degrees Celsius. Generally, these temperature coefficient values are extremely small, in the ppm range.Example: red blue green black brown=265*10^0=265Ω(±1%)ToleranceThe maximum tolerance between the actual resistance and the nominal resistance, represented by percentages. Commonly used are ±5%, ±10%, ±20%, precision is less than ±1%, high precision up to 0.001%. The accuracy is determined by both the tolerance and the irreversible resistance.Power RatingMaximum power dissipation allowed for continuous operation of resistors at rated temperature (maximum ambient temperature) tR. And the maximum operating voltage is also specified for each resistor, that is, the maximum operating voltage cannot be exceeded even if the resistance value is high.Identification of rated Power of ResistorsThe rated power of a resistor refers to the maximum power that a resistor is allowed to consume in a long-term continuous operation in a DC or AC circuit. There are two marking methods: the resistance above 2W is directly printed on the resistor body, and the resistance below 2W is represented by its own volume. When the resistance power is expressed on the circuit diagram, the following symbols are used: 1) Load CharacteristicWhen the working temperature is lower than tR, the resistor can not exceed its rated power, and the load power must be reduced when it exceeds tR. Each resistor has its own specified load characteristic. In addition, the load is allowed to be reduced accordingly at low pressure. Under pulse load, the average power of the pulse is much lower than the rated power, the load is according to the practical situation.2) Resistance Temperature CoefficientThe average relative variation of the resistance value at each change of 1℃ is expressed in terms of ppm/ ℃ within a specified range of ambient temperature. In addition to the above parameters, there are other technical indicators, such as nonlinearity (the extent to which the characteristics of the current and the applied voltage deviate from the linear relationship), the voltage coefficient (the relative rate of change of the voltage at which the voltage is applied, the relative rate of change of the volt resistance), current noise (the ratio of the effective value of the noise potential generated by the current flow in the resistor to the measured voltage, expressed by the current noise index), the high-frequency characteristic (due to the effect of the distributed capacitance and the distributed inductance in the resistor; a curve in which the resistance value decreases as the operating frequency increases; long-term stability (such as irreversible changes in resistance values affected by environmental conditions during long term use or storage).II Resistor CharacteristicsDependent on the application, the electrical engineer specifies different properties of the resistor. The primary purpose is to limit the flow of electrical current; therefore the key parameter is the resistance value. The manufacturing accuracy of this value is indicated with the resistor tolerance in percentage. Many other parameters that affect the resistance value can be specified, such as long-term stability or the temperature coefficient. The temperature coefficient, usually specified in high precision applications, is determined by the resistive material as well as the mechanical design.In high-frequency circuits, such as in radio electronics, the capacitance and inductance can lead to undesired effects. Foil resistors generally have a low parasitic reactance, while wire-wound resistors are amongst the worst. For accurate applications such as audio amplifiers, the electric noise must be as low as possible. This is often specified as microvolts noise per volt of applied voltage, for a 1 MHz bandwidth. For high-power applications, the power rating is important. This specifies the maximum operating power the component can handle without altering the properties or damage. The power rating is usually specified in free air at room temperature. Higher power ratings require a larger size and may even require heat sinks. Many other characteristics can play a role in the design specification. Examples are the maximum voltage or the pulse stability. In situations where high voltage surges could occur this is an important characteristic.Resistors in series and parallel ConnectionIn electronic circuits, resistors are very often connected in series or in parallel. A circuit designer might for example combine several resistors with standard values (E-series) to reach a specific resistance value. For series connection, the current through each resistor is the same and the equivalent resistance is equal to the sum of the individual resistors. For parallel connection, the voltage through each resistor is the same, and the inverse of the equivalent resistor value is equal to the sum of the inverse values for all parallel resistors. In the articles resistors in parallel and series, a detailed description of calculation examples is given. To solve even more complex networks, Kirchhoff’s circuit laws may be used.The Total resistance of resistors connected in series is the sum of each single individual resistance value.The total resistance of resistors connected in parallel is the reciprocal of the sum of the reciprocals of the individual resistors.As a special case of this equation: if you have just two resistors in parallel, their total resistance can be calculated with this slightly-less-inverted equation:Termination and MountingResistors will come in one of two termination types: through-hole or surface-mount. These types of resistors are usually abbreviated as either PTH (plated through-hole) or SMD/SMT (surface-mount technology or device).Through-hole resistors come with long, pliable leads which can be stuck into a breadboard or hand-soldered into a prototyping board or printed circuit board (PCB). These resistors are usually more useful in breadboarding, prototyping, or in any case where you’d rather not solder tiny, little 0.6mm-long SMD resistors. The long leads usually require trimming, and these resistors are bound to take up much more space than their surface-mount counterparts.The most common through-hole resistors come in an axial package. The size of an axial resistor is relative to its power rating. A common 1/2W resistor measures about 9.2mm across, while a smaller 1/4W resistor is about 6.3mm long.Surface-mount resistors are usually tiny black rectangles, terminated on either side with even smaller, shiny, silver, conductive edges. These resistors are intended to sit on top of PCBs, where they’re soldered onto mating landing pads. Because these resistors are so small, they’re usually set into place by a robot and sent through an oven where solder melts and holds them in place.III Resistor TypesMost types of the resistor are linear devices that produce a voltage drop across themselves when an electrical current flows through them because they obey Ohm’s Law, and different values of resistance produce different values of current or voltage. This can be very useful in Electronic circuits by controlling or reducing either the current flow or voltage produced across them we can produce a voltage-to-current and current-to-voltage converter.Resistors come in a variety of shapes and sizes. They might be through-hole or surface-mount. They might be a standard, static resistor, a pack of resistors, or a special variable resistor. The different types of resistors are discussed in the following section.1. Classified by Volt-ampere Characteristic*Linear resistors*Non-linear resistorsFor most conductors, at a certain temperature, the resistance is almost unchanged and is a certain value, the resistors having this kind of resistance is called a linear resistor. The resistors of some materials vary obviously with the current (or voltage) change, and the volt-ampere characteristic of them is a curve, which is called a nonlinear resistor. Under a given voltage (or current), the ratio of voltage to current is the static resistance at the working point, and the slope on the voltage-ampere characteristic curve is dynamic resistance. The expression of nonlinear resistance characteristics is complicated, but these nonlinear relations are widely used in electronic circuits.2. Classified by Material1) Wirewound resistor is made of resistive wires, wound high resistance alloy wires on an insulating skeleton, and coated with a heat-resistant glaze insulating layer or insulating paint. The wire-wound resistor has a low-temperature coefficient, high resistance accuracy, good stability, sound heat resistance, and corrosion resistance. It is mainly used for precise and high power resistance. The shortcoming is that the high-frequency performance is poor and the time constant is large.  ApplicationsIt has high securityAccurate measurement and balance current control is required.2) The carbon composition resistor is made from the mixer of granulated or graphite, an insulation filter, and a resin binder. The actual resistance of the resistor is determined by the ratio of the insulation material. The shape of the insulating binder is in the shape of roads and there are two metal caps at both the end of the roads. At both ends of the resistor, it has two wire conductors for easy connectivity in the circuit design. There are different colors that are printed on the resistor to find the value of it and the road is covered with the plastic coat.   ApplicationsThe composition resistor is used in the high energy pulses.·It has a relatively small size.·High voltage power supplies·Welding·High power3) A carbon film resistor is plated with a carbon layer on the porcelain tube, and the crystalline carbon is deposited on the ceramic rod framework. Furthermore, the temperature coefficient is from -100 to -900 ppm/°C. The carbon film resistor has the advantages of low cost, stable performance, wide resistance range, low-temperature coefficient, and low voltage coefficient, and is the most widely used resistor.  ApplicationsThe carbon film resistors are available in High plus stability.4) A metal film resistor is coated with a layer of metal on the ceramic tube, and the alloy material is plated on the surface of the ceramic rod skeleton by vacuum evaporation.Metal film resistor is more accurate than carbon film resistor, other advantages such as good stability, small noise, low-temperature coefficient. It is widely used in instrumentation and communication equipment.5) Metal oxide film resistors are coated with tin oxide on the ceramic tube, and a layer of metal oxide is deposited on the insulating rod. Because its body is an oxide, so it has high temperature stability, heat shock resistance, sound load capacity. According to the purpose, it is divided into universal, precision, high frequency, high voltage, high resistance, and high power type, also it can forms resistors network.IV Special Resistors1) KNP-RF: it also called a fuse resistor, which functions like a resistor and a fuse in the normal condition. When the circuit fails to make the power exceed the rated power, it will be blown as if the fuse is blown and the connection circuit is disconnected. The general resistance of the fuse resistance is small (0.33Ω ~ 10KΩ), and the power is also small. The common types of fuse resistors are RF10 type, RF111-5 fuse resistor symbol type, RRD0910 type, RRD0911 type, etc.2) Sensitive resistor: a resistor whose resistance value is sensitive to certain physical quantities (such as temperature, humidity, light, voltage, mechanical force, gas concentration, etc.). When these quantities change, The resistance value of the sensitive resistors will change with the change of physical quantity, showing different resistance values. According to the sensitivity to different physical quantities, the sensitive resistor can be classified as heat-sensitive, humidity-sensitive, photosensitive, pressure-sensitive, force-sensitive, magnetic sensitive, and gas sensitive. Sensitive resistors are almost made of semiconductor materials, thus they are also known as semiconductor resistors.The resistance of the thermistor varies with the change of temperature, when the temperature rise, this resistor is a negative temperature coefficient (NTC) thermistor. In most cases, the NTC thermistor is widely used, according to its different use, it can be divided into common NTC thermistor, steady-voltage NTC thermistor, thermometric NTC thermistor, and so on. The resistance of the photosensitive resistor changes with the intensity of the incident light. When the incident light is enhanced, the resistance decreases and the resistance increases when the incident light weakens.V How to Select a Suitable Resistor1) There are many types of fixed resistors, what materials and structures should be selected, it is necessary to consider the specific requirements of the application circuit. In high-frequency circuits, non-wire-wound resistors with small distributed inductance and capacitance should be selected,  such as carbon film resistor, metal resistor, and metal oxide film resistor, thin-film resistor, thick film resistor, alloy resistor, corrosion-resistant film resistor, etc. In high gain and small-signal amplifying circuits, low noise resistors should be used, such as metal film resistors, carbon film resistors, and wire-wound resistors, rather than synthetic carbon film resistors and organic solid resistors with high noise.There are different types of the resistor which are in the following:Carbon compositionCarbon PileCarbon filmPrinted carbon resistorThick and thin filmMetal filmMetal oxide filmWire woundFoil resistorAmmeter shuntGrid resistorSpecial veritiesLed ArrangementThe resistance value of the selected resistor shall be close to a nominal value of the calculated value in the application circuit, and the standard series resistor shall be preferred. The tolerance of resistors used in general circuits is ±5%~±10%. Precision resistors should be used in precision instruments and special circuits, with precision within 1%, such as 0. 01%, 0.1% or 0. 5% tolerance. The rated power of the selected resistor should not be arbitrarily increased or reduced in order to meet the requirements of the power capacity of the resistor in the application circuits.If the circuit is required to be a power resistor, the rated power can be 2 times higher than that required by the practical application circuit.Selection of Fuse ResistorFuse resistor, a kind of resistor with a protective function. The dual performance should be considered and the parameters such as resistance and power should be selected according to the specific requirements of the circuits. It is not only to ensure that it can fuse quickly when it is overloaded but also to guarantee that it can work stably for a long time under normal conditions. In addition, if the resistance is too high or the power is too large, it can not play a protective role either.Three basic principles for the selection of resistors:Select high-level standard resistors manufactured by a production line certified by the certification administrations.Select resistors manufactured by manufacturers with advantages of function, quality, efficiency,  price, and service.Select the manufacturer who meets the above requirements.VI Things Needing AttentionThe resistors should be checked before use, checking their performance is to measure whether the actual resistance value is consistent with the nominal value and whether the error is within the allowable range. The method is to measure the resistance by the multimeter.Two points need to pay attention to when measuring.1)The range should be determined according to the measured resistance when the pointer is indicated in the middle of the scale, which is easy to observe.2)After determining the resistor range, having zero adjustments is that the two table pens are directly touching (short circuit), that is, the "zero adjustments" device is adjusted so that the pointer is accurately pointed to the "0" of the Ω scale, and then the resistance value is measured again. Also, be careful not to touch both ends of the resistor or the metal part of the pen, otherwise, the test error will be caused.If the resistance measured by the multimeter is close to the nominal value, the basic quality is good, and if the difference is big or the multimeter does not work at all, this resistor is bad.VII Resistor Detection1. Appearance CheckFor a fixed resistor, check the logo clear firstly: intact protective paint, no charring, no scars, no cracks, no corrosion, resistive body and pin connected closely. For potentiometers, the axis flexible, proper tight, the comfortable handle should be the key point. If there is a switch, checking the switch whether is working properly.2. Multimeter Detection① detection of fixed resistanceWhen measuring, the different resistances are measured by the proper electric gears of the multimeter. For the pointer type multimeter, because the indicator of electric gear is nonlinear, the larger the resistance value, the more dense the indicator number is, so the more accurate the reading is, the larger the angle of needle deviation should be, to make more accurate reading numbers. If the measured result exceeds the error range of the resistor, the resistance value is infinite, unstable, or zero, which indicates that the resistor has been broken.In the measuring process, the hands holding the resistor should not contact the two pins of the resistor, which will affect the accuracy of the measurement. In addition, the multimeter can not be used to detect the resistance during power on, because online detection shouldn’t be allowed.② Detection of fuse resistors and sensitive resistorsThe resistance range of fuse resistors is generally only a few to dozens of Ω. If the detecting resistance is infinite, it indicates that the fuse has been fused. The resistance can also be measured online, measuring the grounding voltage at both ends respectively, if one end is equal to the power supply voltage and another end voltage is 0V, indicating the fuse resistor has broken.There are many kinds of sensitive resistors, in this section, taking thermistors as an example. As above mentioned, it is divided into positive temperature coefficient(PTC) thermistors and negative temperature coefficient(NTC) thermistors. For the PTC thermistor, the resistance value is usually small at normal temperatures. In the measurement, when using the electric soldering iron with burning heat close to the resistor, the resistance value will be obviously increased, which indicates the resistor is normal, and if no change appears, indicating the component is damaged. The NTC thermistor is the opposite.Under the circumstance without light, the resistance value of light-sensitive resistors is large, on the contrary, the measuring resistance will be reduced obviously when there is light, if there is no change, the component is damaged.③ Detection of variable resistors and potentiometerFirstly, measuring whether the resistance values between the two fixed ends are normal, if the detecting values are infinite or zero, or is larger or small than the nominal values, exceeding the tolerances, which indicates the device is damaged. If the resistance value of the resistive body is normal, then a meter pen of the multimeter is connected with the sliding end of the potentiometer, the other pen is connected with any fixed end of the potentiometer (adjustable resistor), and the footstalk is slowly rotated to observe whether the meter needle is stably changed.when the resistance value is changed from zero to the nominal value (or vice versa) from one end to the other end, and there is no jump or jitter in the course of rotation, which indicating the potentiometer is normal, if any, it is indicated that the sliding point of resistance is in poor contact3. Measuring resistance with bridgeIf the accurate measurement of resistor resistance is required, it can be measured by a bridge (digital). The resistance can be read from the display by inserting the resistor into the measuring end of the bridge by selecting an appropriate range. For example, when a resistor is made from a wire or a fixed resistor is processed to obtain a more accurate resistance value, under this situation, the resistance of the self-made resistor must be measured by a bridge.Different applications, the purpose of applying varistor, different voltage/current stress acting on the varistor, so the requirements for the varistors are different, thus it is necessary to pay attention to detecting. According to the purpose of the application, the varistors can be divided into two categories: the protection varistor and the circuit function varistor.1) Distinguish between the power supply, signal lines, and data wire protection for varistors, because they should meet the requirements of different technical standards.2) According to the difference of the continuous working voltage applied on the varistors, the power lines can be divided into two types: AC or DC, in addition, the aging characteristics of varistors under these two voltage stresses are different.3) According to the abnormal overvoltage of varistors, it can be divided into three types: surge suppression type, high power type, and high energy type.Surge suppression type: it is used to suppress transient overvoltages caused by lightning and improper operation. Transient overvoltages are random, aperiodic, and the peak value of current voltages may be very large.High power type: it is used to absorb a continuous group of pulses occurring in a period, for example, a varistor connected to a switching power converter, where the impulse voltage period occurs, and the period is knowable, so the energy value can generally be calculated. From this, we can see the peak value of voltage is not large, but occurs frequently, thus its average power is quite large.High energy type: it is used to absorb magnetic energy in large inductance coils such as generator excitation coils, lifting electromagnet coils, etc. For such applying requirements, the main technical index is energy absorption capacity.The protection of varistor can be used repeatedly in most applications, but sometimes it can be made into a one-off protection device such as a current fuse. For example, a varistor with short-circuit contact connected to a load of some current transformers. VIII How to Recognize a Resistor1. Color bands resistorThe first and second bands with four color bands represent the first two digits of the resistance respectively; the third band represents the multiplier; the fourth band represents the tolerance.   ColorDigitMultiplierToleranceBlack0100 Brown11011Red21022Orange3103 Yellow4104 Green51050.5Blue61060.25Violet71071Grey8108 White9109 Gold 10-15Silver 10-210None  20(1) The key to fast recognition is to determine the resistance value within a certain magnitude according to the color of the third band, and then to recognize the resistance of first and second band, following this way, the number can be read out quickly.GoldunitsBlacktensBrownhundredsRedthousandsOrangeten thousandsYellowhundred thousandsGreenmillionsBlueten millions(2) Memorize the number of colors represented by the first and second rings, the following table is the number each color represents.On the order of magnitude, they can be divided into three grades: gold, black, brown is Ω; red, orange, yellow are KΩ; green, blue is MΩ.(3) When the second band is black, the third band is represented by an integer, and a special case at the time of reading needs to be noted, for example, the third band is red, the resistance value is a whole number kΩ.(4) Remember the errors represented by the fourth band color, that is, gold is 5%, silver is 10%, colorless is 20%.Examples(1) When the four-color bands are yellow, orange, red, and gold successively because the third ring is red, the resistance range is several kΩ, according to the representing number of yellow and orange is "4" and "3" respectively, the reading number is 4.3 kΩ, and the fourth band is gold, so the error is 5%.(2) When the four-color bands are brown, black, orange, and gold in turn, because the third band is orange and the second band is black, the resistance range should be tens of kΩ, the brown is representing “1”, so the reading number is 10 kΩ, the fourth band is gold, its error is 5%.2. Chip resistorsChip resistors have the advantages of small size, lightweight, high installation density, high seismic resistance, sound anti-interference ability, and good high-frequency characteristic. It is widely used in computers, mobile phones, electronic dictionaries, medical e-products, video cameras, VCD machines,s, etc.Chip components can be divided into three types according to their shape: rectangular, cylindrical, and special-shaped. There are resistors, capacitors, inductors, transistors, and small integrated circuits. The nominal method of the chip components is different from that of the common components. The following is mainly about the nominal method of chip resistors.The resistance value of a chip resistor is the same as that of a general resistor. There are three methods of nominal resistance, but it is not exactly the same as that of general resistors.1) Digital nominal method (usually for general rectangular chip resistors)This method is using a three-digit number on the resistance body to indicate its resistance. Its first digit and second digit are significant digits, and the third digit represents the numbers of "0" added after the significant number, and this digit place does not appear as a letter.Example: “472′” represents “4700Ω”, “151” represents “150”.If it is a decimal, use "R" to denote "decimal point" and take up an effective digit, and the remaining two digits are valid numbers.Example: “2R4” represents “2.4Ω”, “R15” represents “0.15Ω”.2) Colour bands nominal method (used in general cylindrical fixed resistors)The chip resistor, like general resistors, is usually indicated by four/five/six bands. The first band and second band are significant numbers and the third band is a multiplier.IX. Resistor FunctionSmall power resistors are usually made of carbon film packaged in plastic shells, while high power resistors are usually wire wound resistors, which are made by metal wires with high resistance wrapped on the porcelain core.If the resistance value of a resistor is close to 0Ω, the resistor has not any effect on the current. In parallel with this kind of resistors, the circuit will be short-circuited and the current is infinitely large. If resistance is very large or infinite, the circuit is in series with such a resistor can be regarded as an open circuit, that is, the current is 0A. The commonly used resistor in the industry is between two these extreme cases. In other words, it has a certain resistance and can pass through a certain current, but the current is not as large as in a short circuit. The resistor's current limiting effect is similar to that of a small diameter tube connected to two large-diameter tubes to limit water flow. It is defined as the resistance corresponding to that 1V voltage is added to the conductor to generate 1A current, in fact, the term "resistance" refers to a property, whereas in electronic products, it often refers to a component such as a resistor.FAQ1. How does a resistor work?A resistor is a little package of resistance: wire it into a circuit and you reduce the current by a precise amount. ... A resistor like this is described as wire-wound. The number of copper turns controls the resistance very precisely: the more copper turns, and the thinner the copper, the higher the resistance.2. What are the 4 types of resistors?Resistor types:Fixed resistors.Variable resistors.Thermistors.Varistors.Light dependent resistors.3. What is resistor and its unit?Resistor is an electrical component that reduces the electric current. The resistor's ability to reduce the current is called resistance and is measured in units of ohms (symbol: Ω). If we make an analogy to water flow through pipes, the resistor is a thin pipe that reduces the water flow.4. What is resistor in simple words?A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active elements, and terminate transmission lines, among other uses.5. What is the main function of resistor?A resistor is a passive electrical component with the primary function to limit the flow of electric current.6.How do you identify a resistor?Some resistors have contact plates on the bottom. Read the 3 or 4 numbers on the resistor. The first 2 or 3 represent the significant digits and the last indicates the number of 0s that should follow. For example, a resistor reading 1252 indicates a rating of 12,500 ohms or 1.25 kilo-ohms.7. What is resistor formula?According to Ohm's law, the voltage drop, V, across a resistor when a current flows through it is calculated by using the equation V=IR, where I is current in amps (A) and R is the resistance in ohms (Ω). So the voltage drop across R1 is V1=IR1, across R2 is V2=IR2, and across R3 is V3=IR3.8. What is difference between resistor and resistance?Resistance is the property of a conductor, which determines the quantity of current that passes through it when a potential difference is applied across it. A resistor is a electrical componet with a predetermined electrical resistance, like 1 ohm, 10 ohms 100 ohms 10000 ohms etc.9. What are the 2 types of resistors?The resistors are mainly divided into two types, first Fixed Resistors and second, variable resistors. In Fixed resistors, the electrical resistance of the resistor the remains same while in variable resistor it does change with some physical variable.10. What are the five examples of fixed resistor?The different types of fixed resistors include:Wire wound resistor.Carbon composition resistor.Carbon film resistor.Metal film resistor.Metal oxide film resistor.Metal glaze resistor.Foil resistor.11. What can be used as a resistor?Explained another way: an electrical circuit that has a difference of 2 volts, with 1 Ampere of current flowing through it, has a resistance of 2 Ohms. All electrically conductive materials are somewhat resistive, too. Because of this, even a good electrical conductor, such as metal wire, can be used as a resistor.12. How do you use a resistor in a circuit?Dividing voltage: You can also use resistors to reduce voltage to a level that's appropriate for specific parts of your circuit. For example, suppose your circuit is powered by a 3 V battery but a part of your circuit needs 1.5 V. You could use two resistors of equal value to split this voltage in half, yielding 1.5 V.13. What happens if there is no resistor in a circuit?If there really were no resistance in the circuit, the electrons would go around the circuit, and arrive back at the beginning of the circuit with as much energy as the potential difference (the voltage). That final energy is usually what is dissipated as heat or other types of energy by the circuit.14. How do you connect a resistor?Resistors are said to be connected in “Series”, when they are daisy chained together in a single line. Since all the current flowing through the first resistor has no other way to go it must also pass through the second resistor and the third and so on.15. What is the use of resistor color code?Components and wires are coded with colors to identify their value and function. Resistor Color Coding uses colored bands to quickly identify a resistors resistive value and its percentage of tolerance with the physical size of the resistor indicating its wattage rating.You May Also LikeHow to Distinguish Resistor Color Codes? (Axial Resistors)

2026 Executive Summary: The MAP SensorThe Manifold Absolute Pressure (MAP) sensor is a critical component in modern internal combustion and hybrid engines. It measures air pressure inside the intake manifold to calculate air density and determine the precise fuel mass required for combustion. Failure leads to poor fuel economy, rough idling, and failed emissions tests.Key Data Points (2026):Lifespan: Typically 80,000 to 100,000 miles.Replacement Cost: $50–$250 (Part) + $100–$200 (Labor).Primary Codes: P0106, P0107, P0108.Why is the MAP Sensor Important in 2026?The powertrain control module (PCM) relies on the Manifold Absolute Pressure (MAP) sensor to monitor intake manifold pressure instantaneously. Because pressure is inversely related to vacuum, the PCM utilizes the MAP sensor input to calculate engine vacuum and load with high precision. In modern 2026 vehicle architectures, including hybrids, this data controls fuel injection pulse width, ignition timing, and EGR flow.This comprehensive guide details the diagnostic power of the MAP sensor, updated for 2026 maintenance standards.Video: Testing a MAP Sensor with modern diagnostic tools.Ⅰ What is a MAP Sensor?A MAP (Manifold Absolute Pressure) sensor is an electronic device that calculates air density by measuring the pressure variance inside the intake manifold. The Engine Control Unit (ECU) uses this real-time data to adjust the air-fuel mixture to the ideal stoichiometric ratio (14.7:1 for gas engines) and optimize ignition timing. This ensures the engine operates efficiently, minimizing emissions and maximizing power output.Ⅱ What is the Main Function of a MAP Sensor?The primary function of the MAP sensor is to provide the PCM with instantaneous manifold pressure data to calculate engine load. Specifically, it allows the computer to decide exactly how much fuel to inject into the cylinders. Furthermore, it retards or advances ignition timing to prevent "spark knock" (detonation), protecting internal engine components from severe damage.Ⅲ How Does A MAP Sensor Work (Technical Breakdown)Figure: Piezoresistive element operation within the sensor.The MAP sensor functions by converting intake air pressure changes into a voltage signal recognizable by the ECU. Modern sensors utilize a technology called piezoresistivity.The Mechanism: Inside the sensor housing lies a sealed vacuum chamber covered by a flexible silicon chip (diaphragm).Engine Off: When the engine is off, the pressure inside the manifold equals atmospheric pressure. This baseline helps the ECU determine altitude/air density.Engine Idle: When the engine starts, the pistons create a vacuum, lowering the pressure. The silicon chip flexes, altering its electrical resistance.Acceleration: When the throttle opens, air rushes in, increasing pressure (reducing vacuum). The chip flexes upward, resistance drops, and the output voltage signal to the ECU rises.The ECU processes this voltage spike (typically 0.5V to 4.5V range) to immediately enrich the fuel mixture for acceleration.Ⅳ Why is the MAP Sensor Critical for Fuel Economy?The MAP sensor ensures that the engine does not waste fuel or run too lean (which causes overheating). By providing "Total Mass Air Flow" calculations indirectly, it allows the vehicle to adapt to changing environments—such as driving from sea level to a high-altitude mountain pass—without driver intervention.Ⅴ 9 Common Bad MAP Sensor Symptoms (2026 Update)Diagnosing a failing sensor early prevents catalytic converter damage. Always start by scanning for Diagnostic Trouble Codes (DTCs).1. Check Engine Light (DTC P0106 - P0109)The most reliable indicator. Common codes include P0106 (Range/Performance), P0107 (Low Input), and P0108 (High Input). Note: A vacuum leak can trick the sensor into triggering these codes even if the sensor itself is healthy.2. Decreased Engine PowerIf the ECU cannot read load, it defaults to a "safe mode," retarding timing and reducing fuel, making the car feel sluggish—especially on inclines.3. Hard StartingWithout an atmospheric pressure reading at key-on, the ECU may inject too little or too much fuel for startup.4. Poor Fuel EconomyThe ECU may default to a "rich" mixture to protect the engine, causing a noticeable drop in MPG (often 10-20% reduction).5. Rough IdleFluctuating RPMs while stopped are common. The engine may hunt for a steady idle as the ECU struggles to compensate for missing pressure data.6. Engine MisfiresLean mixtures cause "lean pops," while rich mixtures foul spark plugs. Both result in misfires that shake the vehicle.7. Rich Fuel Smell from ExhaustIf the sensor reads high pressure erroneously, the ECU dumps excess fuel. This unburned fuel exits the tailpipe, creating a strong gasoline odor and potentially ruining the catalytic converter.8. SurgingYou may feel the car speed up or slow down unexpectedly while maintaining a steady throttle position.9. Failed Emission TestsHigh NOx (from running lean) or high HC/CO (from running rich) will cause an immediate failure in state inspections.Ⅵ How to Replace a MAP Sensor (Step-by-Step)Replacing a MAP sensor is typically a Level 1 DIY repair achievable in 15 minutes.Safety First: Disconnect the negative battery terminal to reset the ECU and prevent shorts.Locate: Find the sensor on the intake manifold (usually top or side) or connected via a vacuum hose near the firewall.Disconnect: Unclip the electrical harness. If there is a locking tab, slide it back first.Remove: Unscrew the retaining bolts (usually T20 Torx or 10mm) or carefully pull the sensor if it is held by friction/O-rings.Install: Lubricate the O-ring of the new sensor with a drop of clean oil, push it in, secure bolts, and reconnect the harness.Ⅶ Diagnostic Workflow: Is it the Sensor or Wiring?Before purchasing parts, verify the failure:1. Electrical CheckInspect the connector for corrosion or bent pins. Wiggle the wires while the engine idles; if the idle changes, you have a wiring short or open circuit, not a bad sensor.2. Vacuum Hose CheckIf your sensor connects via a hose, check for cracks. A $2 hose replacement often fixes "Bad Sensor" codes. Ensure the intake port is free of carbon buildup.3. Voltage TestWith the key ON (engine off), a healthy sensor reads atmospheric pressure (approx 4.5V or 100kPa). Upon starting, voltage should drop to approx 1.0V-1.5V. If it stays stuck, replace the sensor.Ⅷ Can You Clean a MAP Sensor?Yes, but with caution. Sensors blocked by carbon or blow-by oil can be restored.Remove Sensor: Carefully extract the sensor from the manifold.Select Cleaner: Use a dedicated Electronic Parts Cleaner or MAF Sensor Cleaner. Do not use Brake Cleaner, as it can melt the plastic housing and destroy the membrane.Spray: Hold the sensor with the port facing down. Spray the cleaner gently into the port.NO TOUCHING: Never insert a cotton swab, screwdriver, or compressed air into the sensor port. The silicon chip is thinner than a human hair and will break.Dry: Allow it to air dry completely (about 10 minutes) before reinstalling.If cleaning does not clear the error code, the piezoresistive electronics have failed and the unit must be replaced.Ⅸ MAP vs. MAF: What is the Difference?Most 2026 vehicles use both, but they function differently.MAP (Manifold Absolute Pressure): Measures Pressure (Air Density). Located on the manifold. Better for estimating load on turbocharged engines.MAF (Mass Air Flow): Measures Air Volume/Mass. Located on the intake tube before the throttle body. More precise for fuel tuning but sensitive to vacuum leaks.FeatureMAP SensorMAF SensorReliabilityHigh. Not affected by air leaks before the sensor.Sensitive. Any leak after the sensor throws off readings.PrecisionCalculated Load (Indirect).Actual Flow (Direct). More accurate for MPG.Ⅹ How Much Does MAP Sensor Replacement Cost in 2026?Prices have adjusted for the 2026 market. Replacing a MAP sensor remains an affordable repair relative to the damage ignoring it causes.DIY Cost: $40 to $150 for the part (Aftermarket vs. OEM).Professional Repair: $150 to $400 total.Note: Professional labor rates in 2026 average $120–$180 per hour. Since this is a quick job, shops often charge a minimum 1-hour diagnostic/labor fee.Ⅺ Frequently Asked Questions (FAQ)1. Do I need to upgrade my MAP sensor for tuning?Yes, only if adding a turbocharger. Stock sensors typically read up to 1 Bar (atmospheric). Boosted engines require 2-Bar or 3-Bar sensors to read positive pressure. You will need a "Plug-and-Play" adapter and an ECU retune to scale the new voltage map.2. Does a bad MAP sensor always throw a code?Not always. A sensor can be "lazy"—reading slowly or slightly off-spec—without triggering a hard fault code immediately. However, you will likely see "Pending Codes" on an OBD2 scanner before the check engine light turns on.3. Is it safe to drive with a bad MAP sensor?You can drive short distances in an emergency, but it is not recommended. The car may stall at intersections, suffer from severely reduced power ("Limp Mode"), and dump unburned fuel into the exhaust, which can destroy your catalytic converter—a repair costing over $1,000.4. Can a bad MAP sensor cause a misfire?Yes. If the sensor reports higher pressure than actual, the ECU injects too much fuel, fouling the spark plugs and causing misfires. Conversely, a low reading causes a lean misfire.5. Why does a bad MAP sensor prevent the car from starting?The ECU uses the MAP sensor reading before the engine cranks to determine barometric pressure. If this initial reading is dead, the ECU cannot calculate the initial fuel prime, leading to a "crank, no start" condition.6. How long do MAP sensors last?Modern sensors are designed for the life of the engine but realistically fail between 80,000 and 100,000 miles due to heat cycles and carbon contamination from the intake manifold.7. Will a bad MAP sensor trigger Limp Mode?Yes. Because the MAP sensor is critical for load calculation, losing its signal forces the ECU into "Open Loop" or Limp Mode to protect the engine, significantly restricting RPM and speed.{ "@context": "https://schema.org", "@type": "Article", "headline": "The Ultimate Guide to MAP Sensors: Symptoms, Function & Replacement (2026)", "datePublished": "2022-05-16", "dateModified": "2026-01-08", "author": { "@type": "Organization", "name": "ApogeeWeb Tech Team" }, "mainEntity": [ { "@type": "FAQPage", "mainEntity": [ { "@type": "Question", "name": "What is a MAP Sensor?", "acceptedAnswer": { "@type": "Answer", "text": "A Manifold Absolute Pressure (MAP) sensor is an electronic component that measures the pressure inside the intake manifold to help the engine control unit (ECU) calculate air density and determine the correct fuel injection rate." } }, { "@type": "Question", "name": "What are the symptoms of a bad MAP sensor?", "acceptedAnswer": { "@type": "Answer", "text": "Common symptoms include a Check Engine Light (codes P0106-P0109), poor fuel economy, rough idling, hard starting, engine misfires, and a smell of gas from the exhaust." } }, { "@type": "Question", "name": "Can you clean a MAP sensor?", "acceptedAnswer": { "@type": "Answer", "text": "Yes, you can clean a MAP sensor using specialized electronic parts cleaner. However, do not touch the internal sensor element with any physical object, as it is fragile." } }, { "@type": "Question", "name": "How much does it cost to replace a MAP sensor in 2026?", "acceptedAnswer": { "@type": "Answer", "text": "In 2026, the part typically costs between $40 and $150. If you hire a professional, expect to pay an additional $100 to $200 in labor, bringing the total to $150–$350." } } ] }, { "@type": "HowTo", "name": "How to Clean a MAP Sensor", "step": [ { "@type": "HowToStep", "name": "Locate and Remove Sensor", "text": "Disconnect the negative battery terminal, locate the MAP sensor on the intake manifold, unplug the connector, and remove the screws." }, { "@type": "HowToStep", "name": "Inspect Sensor", "text": "Check for carbon buildup or oily residue on the sensor port." }, { "@type": "HowToStep", "name": "Apply Cleaner", "text": "Spray Electronic Parts Cleaner or MAF Cleaner into the sensor port. Do not use brake cleaner or touch the element." }, { "@type": "HowToStep", "name": "Dry and Reinstall", "text": "Shake out excess fluid gently and let it air dry for 10 minutes before reinstalling." } ] } ]}

2026 Executive SummaryThis authoritative guide explores the function, diagnostics, and wiring of Start Relays in modern HVAC and automotive systems. As of 2026, start relays remain the critical failure point in 15-20% of refrigeration breakdowns. We cover the three primary architectures (Current, PTC, and Potential), provide step-by-step troubleshooting for multimeter testing, and detail updated 12V wiring standards for automotive ignition systems.Introduction: The Role of Start Relays in 2026The Start Relay is a specialized electromechanical component designed to initiate the rotation of single-phase asynchronous motors. In the 2026 landscape of home appliances and automotive engineering, its primary function is to momentarily engage the auxiliary (start) winding or starter solenoid to overcome inertia. While variable-frequency drives (VFDs) are gaining popularity, the vast majority of residential refrigerators and air conditioners still rely on single-phase split-phase induction motors, necessitating precise relay activation. Once the motor reaches approximately 75% to 80% of its rated speed, the relay automatically disconnects the start circuit to prevent the auxiliary winding from overheating or burning out.Ⅰ What is a Start Relay and How Does It Work?A start relay is an automatic switch that utilizes electromagnetic force or thermal resistance to control the high-current startup phase of an electric motor.Technically, start relays fall under the category of momentary control switches. They utilize electromagnetic and electromechanical principles to bridge contacts within a control circuit. A relay system comprises two distinct loops:The Control System (Input Loop): Responds to physical quantities like electricity or heat.The Controlled System (Output Loop): Manages the high-load circuit.When the input parameter (e.g., inrush current) hits a specific threshold, the output state changes abruptly from zero to a set value, effectively managing circuit protection and power transmission without manual intervention.Figure 1. Standard Electrical Relay Symbols (IEC/NEMA Standards)Ⅱ Applications: HVAC vs. Automotive SystemsStart relays are predominantly used in single-phase refrigeration compressors to engage torque windings and in automobiles to switch high-amperage starter currents.1. HVAC & Refrigeration:The starting relay is the control element that automates the induction motor startup. When a refrigerator compressor cycles on, the motor winding is energized; once stable operation is achieved, the relay cuts power to the start winding. In 2026, the three industry-standard types found in appliances are:Current Relays: Common in older, smaller units.PTC (Positive Temperature Coefficient): The standard for modern residential fridges.Potential (Voltage) Relays: Used in high-torque commercial HVAC units.2. Automotive Systems:In vehicles, the start relay acts as a low-current switch controlling a high-current circuit. It preserves the ignition switch by handling the heavy load required to engage the starter solenoid. When activated, it drives the magneto rotor, inputs an ignition pulse, and ultimately allows the spark plugs to ignite the air-fuel mixture in the cylinders. Ⅲ Types of Start Relays: 2026 Industry Overview3.1 Current Starting Relays (Magnetic)Current relays operate by sensing the high inrush current drawn by the motor at a standstill.The coil is connected in series with the compressor's run winding. When the motor is stationary, the current is high, creating a strong magnetic field that closes the contacts to engage the start capacitor/winding. As speed increases, current drops, and gravity (or a spring) opens the contacts.(1) Heavy Hammer (Gravity) RelayThis legacy design relies on gravity to reset the armature. It consists of a coil, armature, moving contact, and static contact.Figure 2. Structure of a Heavy Hammer Start RelayMechanism: The contacts are Normally Open (NO). Upon power-up, the massive starting current (often 5-6x rated amps) magnetizes the coil, lifting the armature to close the start circuit. As the motor speeds up, current drops, and the armature falls, disconnecting the start winding. Note: These must be mounted perfectly vertical to function.(2) PTC Start Relay (Solid State)The most common relay in modern refrigerators. The PTC element is a barium titanate semiconductor. In its cold state (room temperature), resistance is low (approx. 4.7Ω to 33Ω), allowing current to pass.Mechanism: As high current flows during startup, the ceramic disc self-heats to its Curie point (100°C - 140°C). Resistance spikes effectively to infinity (open circuit), cutting off the start winding.Figure 3. PTC Start Relay Wiring SchematicAdvantages: No moving parts, high reliability, and low cost. Disadvantages: Requires a "cool down" period of 3-5 minutes between cycles to reset low resistance.(3) Mercury Start RelayA high-durability, non-arcing design often used in hazardous environments. It uses a plunger coil and a mercury reservoir.Figure 4. Mercury Relay Internal StructureWhen energized, the plunger displaces mercury, bridging the electrodes to complete the circuit. While highly reliable, environmental regulations in 2026 have limited their production due to mercury toxicity.Figure 5. Automotive Start Relay Assembly3.2 Potential (Voltage) RelaysPotential relays are voltage-sensing devices used in high-torque applications (central AC units, heat pumps).Figure 6. Potential Relay Internal ArchitectureThe coil operates on Back Electromotive Force (Back EMF) generated by the start winding. The contacts are Normally Closed (NC).Startup: Contacts are closed; full power goes to start capacitor/winding.Run: As motor speed hits ~80%, the Back EMF voltage across the start winding increases.Disengage: When voltage exceeds the "Pick-Up" rating (e.g., 300V), the coil energizes, opening the contacts and removing the start gear. Ⅳ Troubleshooting: Why Do Start Relays Fail?4.1 Symptoms of Relay FailureA failed relay usually results in a compressor that "hums" but won't start (clicking sound) or a car that won't turn over.Common Failure Modes:Contact Fusion: Contacts weld together due to electrical arcing, keeping the start winding engaged until the overload trips.Coil Burnout: The internal copper winding breaks or shorts due to overheating.Carbon Buildup: Increases resistance across contacts, causing voltage drops.Fatigue: Return springs lose elasticity over thousands of cycles.Relay wire connections should also be checked for corrosion or looseness, which mimics relay failure.4.2 Automotive Diagnostic Case StudyScenario: The driver turns the key, but the engine does not crank.🔺Case 1: Total Silence (No Crank)Potential Causes:Power Supply: Battery voltage < 12.4V or corroded terminals.Ignition Switch: Signal not reaching the relay control terminal (86).Relay Coil: Open circuit in the relay electromagnet.Diagnostic Steps:Check Power: Turn on headlights. Significant dimming suggests a weak battery.The "Bypass" Test: Use a screwdriver to momentarily bridge the large terminals on the starter solenoid. (Caution: Sparks will occur). If it cranks, the starter motor is good, pointing to a bad relay or ignition switch.Relay Swap: Swap the starter relay with a similar relay (e.g., Horn or Wiper) from the fuse box to test function.🔺Case 2: Slow Cranking (Dragging)Causes: High resistance in relay contacts or worn starter brushes.Fix: Measure voltage drop across the relay terminals while cranking. A drop >0.2V indicates bad contacts.🔺Case 3: Starter Spinning (Whirring) but Engine Not TurningAnalysis: The starter motor is running, but the bendix gear is not engaging the flywheel. This is typically a mechanical failure of the starter drive (Bendix), not the relay itself.Figure 7. Thermal Overload Relay Structure (Often paired with Start Relays)For a visual guide on testing, refer to the tutorial below:Video: How To Test and Replace A Starter RelayⅤ Step-by-Step: Wiring a 12V Starter RelayWiring a standard 4-pin 12V relay follows the DIN 72552 standard numbering system.The goal is to use a low-current signal (Pin 85/86) to switch a high-current path (Pin 30/87).Figure 8. 12V Start Relay Wiring DiagramStandard Pin Configuration:Pin 30 (High Power In): Connect directly to the Battery Positive (+). Fused.Pin 87 (High Power Out): Connect to the load (Starter Solenoid/Motor).Pin 86 (Control Power): Connect to the Ignition Switch (Start position).Pin 85 (Ground): Connect to the Chassis Ground (-).Installation Tips for 2026: Ensure wire gauge for Pins 30/87 is sufficient for the amperage (typically 10-12 AWG or larger for main starter leads). Control wires (85/86) can be thinner (16-18 AWG). If the relay has a diode (protection), ensure Pin 85 and 86 are not reversed to avoid shorting. Ⅵ FAQ: Top Questions About Start Relays1. What is the primary purpose of a starting relay?A starting relay manages high-current loads. It allows a low-current signal (like turning a key) to activate a high-current device (like a starter motor) without melting the ignition switch or wiring. 2. How do I know if my refrigerator relay is bad?The most common sign is a "click-buzz-click" cycle where the compressor tries to start but fails. Additionally, if you remove the relay and shake it, a rattling sound indicates the internal ceramic PTC disc has shattered. 3. Can I bypass a refrigerator start relay temporarily?Technically yes, for testing purposes only. You can momentarily bridge the Run and Start pins on the compressor to jump-start it. However, never leave it bypassed permanently, as the start winding will overheat and destroy the compressor within minutes. 4. What are the symptoms of a bad automotive starter relay?Symptoms include a silent start (no noise when turning key), a rapid clicking sound (insufficient voltage transfer), or the starter remaining engaged after the engine starts (welded contacts). 5. How long is the lifespan of a starter relay?Modern OEM relays are designed for approximately 50,000 to 100,000 cycles, typically lasting the life of the vehicle (100,000+ miles) or 10-15 years for household appliances. 6. Is a starter relay the same as a starter solenoid?They are often confused but distinct. The relay is a small remote switch (usually in the fuse box) that sends power to the solenoid. The solenoid is physically mounted on the starter motor; it pushes the drive gear into the flywheel and bridges the massive battery cables.{ "@context": "https://schema.org", "@graph": [ { "@type": "Article", "headline": "Start Relays Explained: Types, Diagnostics, and Wiring (2026 Guide)", "datePublished": "2021-10-18", "dateModified": "2026-01-09", "description": "A comprehensive guide to Start Relays for HVAC and Automotive applications. Learn about PTC, Current, and Potential relays, including wiring diagrams and troubleshooting steps.", "image": "https://www.kynix.com/editor_u/image/20211018/2021101815335454.jpg", "author": { "@type": "Organization", "name": "Kynix Electronics" } }, { "@type": "FAQPage", "mainEntity": [ { "@type": "Question", "name": "What is the primary purpose of a starting relay?", "acceptedAnswer": { "@type": "Answer", "text": "A starting relay manages high-current loads. It allows a low-current signal (like turning a key) to activate a high-current device (like a starter motor) without melting the ignition switch or wiring." } }, { "@type": "Question", "name": "How do I know if my refrigerator relay is bad?", "acceptedAnswer": { "@type": "Answer", "text": "The most common sign is a 'click-buzz-click' cycle where the compressor tries to start but fails. If you shake the relay and it rattles, the internal PTC disc is likely shattered." } }, { "@type": "Question", "name": "Is a starter relay the same as a starter solenoid?", "acceptedAnswer": { "@type": "Answer", "text": "No. The relay is a low-current switch in the fuse box that activates the solenoid. The solenoid is a high-current device mounted on the starter motor that engages the physical gears and main battery power." } } ] }, { "@type": "HowTo", "name": "How to Wire a 12V Starter Relay", "step": [ { "@type": "HowToStep", "name": "Connect High Power Input", "text": "Connect Pin 30 directly to the positive terminal of the battery (fused)." }, { "@type": "HowToStep", "name": "Connect Control Input", "text": "Connect Pin 86 to the ignition switch output." }, { "@type": "HowToStep", "name": "Connect Ground", "text": "Connect Pin 85 to the vehicle chassis ground." }, { "@type": "HowToStep", "name": "Connect Load", "text": "Connect Pin 87 to the starter solenoid or motor input." } ] } ]}

  A MOSFET is a four-terminal device having source(S), gate (G), drain (D), and body (B) terminals. In general, the body of the MOSFET is in connection with the source terminal thus forming a three-terminal device such as a field-effect transistor. MOSFET is generally considered as a transistor and employed in both analog and digital circuits. This is the basic introduction to MOSFET. Let’s step into the world of MOSFET and find out its secret.     Catalog   I. What is MOSFET? 1.1 Brief Introduction 1.2 MOSFET Structure 1.3 Electrical Symbol and Types 1.4 MOSFET Operating Principle II. MOSFET Selection III. MOSFET Gate Material IV. MOSFET Advantage V. MOSFET Technology VI. Common MOSFET Failures VII. MOSFET Well-known Brands FAQ   I. What is MOSFET?   1.1 Brief Introduction     MOSFET(metal-oxide-semiconductor field-effect transistor) is a type of field-effect transistor (FET), most commonly fabricated by the controlled oxidation of silicon. It has an insulated gate, whose voltage determines the conductivity of the device. This video will cover the basics of what you need to use it in your circuit, including calculating if you need a heat sink or not.   MOSFET (metal-oxide semiconductor field-effect transistor) is a kind of field effect transistors (FET), that is, the gate of metal layer (M) is separated by oxide layer (O) to control the semiconductors (S) by the field effect transistor.   1.2 MOSFET Structure   Fig. 1 mosfet body structure Fig. 1 is a cross-sectional view of a typical N-channel enhanced NMOSFET diagram. a P-type silicon semiconductor material is used as a substrate, two N-type regions are diffused on the surface of the substrate, a layer of silicon dioxide (SiO2) insulating layer is covered on the substrate, and finally, two holes are formed by using an etching method over the N region. The metallization method is used to make three electrodes: G (gate), S (source), and D (drain) in the insulating layer and the two holes, respectively.   From Fig. 1, we can see that the gate G is insulated from drain D and source S, and there are two PN junctions between D and S. In general, the substrate and the source S are connected internally, in other words, there is a PN junction between D and S.   Fig. 1 is a basic block diagram of a common n-channel enhancement MOSFET. To improve the performance of some parameters, such as improving the working current, increasing the working voltage, reducing the on-resistance, improving the switching characteristic, and so on. With different structures and processes, there are VMOS, DMOS, TMOS, etc. Although their structures are different, the working principle is the same.   1.3 Electrical Symbol and Types Fig. 2 mosfet symbols There are many variations in circuit symbols commonly used in MOSFET. The most common design is to represent the channel in a straight line, two lines perpendicular to the channel to represent the source and drain, and the left and the channel parallel and shorter lines to represent the grid. Sometimes a straight line representing the channel is replaced by a broken line to distinguish between an enhancement mode MOSFET or a depletion mode MOSFET and each mode divided into two types respectively, NMOSFET and PMOSFET. Fig. 3 NMOSFET and PMOSFET     Depletion Mode: the Gate-Source voltage of a transistor switches the device “OFF”. The depletion-mode MOSFET is equivalent to a “Normally Closed” switch.   Fig. 4 structure and electrical symbol  (depletion mode mosfet)   Enhancement Mode: the Gate-Source voltage of a transistor switches the device “ON”. The enhancement-mode MOSFET is equivalent to a “Normally Open” switch.   Fig. 5 enhancement type MOSFET(channel structure) Since the MOSFET on the integrated circuit chip is a four-terminal component, there is a bulk or body except for the gate, source and drain. The arrow extending from the channel to the right can indicate that the component is an NMOSFET or PMOSFET. In addition, the arrow direction is always pointed from the P end to the N end, so the arrow points from the channel to the base is the P-type MOSFET, abbreviated PMOS.   On the contrary, if the arrow points from the base to the channel, the base is P-type, and the channel is N-type, which is the N-type MOSFET. In a typical discrete device, that base and source are typically connected together so that the distributed MOSFET is typically a three-terminal element. Whereas a MOSFET in an integrated circuit, the polarity of the base is not indicated because of the use of the same base, and a circle is added to the gate terminal of the PMOS to distinguish.     P-Channel MOSFET: It has a P-Channel region between source and drain. It is a four-terminal device such as gate, drain, source, body. The drain and source are heavily doped p+ region and the body or substrate is n-type. The flow of current is positively charged holes. When we apply the negative gate voltage, the electrons present under the oxide layer are pushed downward into the substrate with a repulsive force. The depletion region populated by the bound positive charges which are associated with the donor atoms. The negative gate voltage also attracts holes from the p+ source and drain region into the channel region.       N- Channel MOSFET: It has an N-channel region between source and drain. It is a four-terminal device such as gate, drain, source, body. In this type of MOSFET, the drain and source are heavily doped n+ region and the substrate or body is P-type. The current flows due to the negatively charged electrons. When we apply the positive gate voltage the holes present under the oxide layer pushed downward into the substrate with a repulsive force. The depletion region is populated by the bound negative charges which are associated with the acceptor atoms. The electron's reach channel is formed. The positive voltage also attracts electrons from the n+ source and drains regions into the channel. Now, if a voltage is applied between the drain and source the current flows freely between the source and drain and the gate voltage controls the electrons in the channel. Instead of positive voltage if we apply negative voltage a hole channel will be formed under the oxide layer.       Therefore, the MOSFET has 4 modes: P-channel enhancement mode, P-channel depletion mode, N-channel enhancement mode, N-channel depletion mode. Their circuit symbols and application characteristic curves are shown in the following figure.  Fig. 6 circuit symbols and application characteristic curves of MOSFET 1.4 MOSFET Operating Principle The internal structure and electrical symbols of power MOSFET can be divided into NPN type and PNP type. That is, the source and drain poles of the N-channel FET are connected to the N-type semiconductor, and the source and drain of the P-channel FET are connected to the P-type semiconductor. We know that the output current of the general transistor is controlled by the input current. But for field-effect transistors, the output current is controlled by the input voltage (or field voltage), which can be considered to be minimal or no input current, causing the device to have a high input impedance, and it is the reason why we call it a FET.   The working principle of power MOSFET is as follows: adding positive power supply between drain and source, and no voltage between gate and sources. The PN junction J1 formed between drain and source is anti-biased, and there is no current flow between drain-source.    Conductive: adding the positive voltage UGS, the gate is insulated between the gate and source, so there will be no gate current flowing through. However, the positive voltage of the gate pushes the hole in the P region below it and attracts the minority electron in the P region to the surface of the P region below the gate when the UGS is greater than the UT (on voltage or threshold voltage). The electron concentration on the surface of the P region under the gate will exceed the hole concentration, making the P-type semiconductor invert into the N-type. For the inversion layer, the N-channel is formed and the PN junction J1 is disappeared, and meanwhile, the drain electrode and the source electrode are conductive.    Basic static characteristics of power MOSFET: Its transfer and output characteristics are shown in Fig. 7.   Fig. 7 transfer and output characteristics of mosfet The relationship between drain current ID and voltage UGS between gate and source is called the transfer characteristic of MOSFET. When ID is large, the relationship between ID and UGS is approximately linear, and the slope of the curve is defined as grid-anode transconductance Gfs.   The voltage-current characteristic (output characteristics) of drain include the cut-off region (corresponding to the cut-off region of GTR), the saturated region (corresponding to the magnification region of GTR), and the unsaturated region (corresponding to the saturation region of GTR). The MOSFET operates in the on-off state, that is, switching back and forth between the cut-off zone and the unsaturated zone. There are parasitic diodes between the drain and source, and the devices are on when a reverse voltage is added between the drain and source. The on-state resistance of the power MOSFET has a positive temperature coefficient, which is beneficial to the current sharing of the devices in parallel.   1. Cut-off Region: with the transistor acting as an open switch, the gate-source voltage is much lower than the transistor's threshold voltage so the MOSFET transistor is switched off fully.   2. Linear (Ohmic) Region: the transistor is in its constant resistance region behaving as a voltage-controlled resistance whose resistive value is determined by the gate voltage.   3. Saturation Region: the transistor is in its constant current region and is therefore switched on fully. The Drain current is equal to the maximum with the transistor acting as a closed switch.   Dynamic Properties   On-delay time (Td): it is the time experienced when the gate-source voltage rises to 10% of the gate drive voltage to the specified current rises to 10%.   Rise time (Tr): it is the time taken to increase the drain current from 10% to 90%. The ID steady-state value is determined by the drain-source voltage UE and the drain load resistance. The UGSP is related to the steady-state value of the ID, and when the UGS reaches the UGSP, it continued to increase until it reached the steady-state, but the ID did not change.   Turn-on time: the sum of turn-on delay time and rise time.   Turn-off delay time (Td): it refers to the time from when the voltage between gate and source drops to 90% of the gate drive voltage to the leakage current of 90% of the specified current. This shows the delay before the current is transferred to the load.    Drop time: it is the time experienced by the drain current drops from 90% to 10%.    Turn-off time: the sum of the turn-off delay time and drop time.   Understand several commonly used parameters of MOSFET. VDS is the drain-source voltage, which is an absolute parameter rating of MOSFET, which indicates the maximum voltage value that MOSFET can bear between drain and source. It is important to note that this parameter is related to junction temperature, and the higher the junction temperature is, the greater the value is. RDS (on), refers to the leakage source on-resistance, which represents the on-resistance between drain and source when MOSFET is on under certain conditions.    This parameter is related to MOSFET junction temperature and driving voltage Vgs. In a certain range, the higher the junction temperature, the greater the Rds, the higher the driving voltage, the smaller the Rds. Qg is the gate charge, gate charge is the charge required to increase the gate voltage from 0V to the termination voltage (such as 15V) under the action of the driving signal.   That is the charge required by the driving circuit from the cut-off state to the full-on state, which is the main parameter used to evaluate the driving ability of the driving circuit of the MOSFET. Id (drain current), is usually described in several different ways. According to the form of the working current, it divided into the continuous drain current and the pulse drain current.    In addition, it is also an absolute parameter rating of MOSFET, but this maximum current value does not mean that the drain current can reach this value during operation. It means that when the shell temperature is at a certain point if the operating current of MOSFET is the maximum drain current mentioned above, the junction temperature will reach the maximum value. Thus this parameter is also related to device packaging and ambient temperature.   Eoss (output volume energy), representing the output capacitance Coss stored in the MOSFET. Because the output capacitance Coss of MOSFET has very obvious nonlinear characteristics, it varies with the change of Vds voltage. If the datasheet identifies this parameter, it will be helpful to evaluate the switching loss of the MOSFET. The current rate of the body diode di/dt reflects the MOSFET reverse recovery characteristics. Because the diode is a bipolar device, it is affected by the charge storage, when the diode reverses bias, the charge stored in the PN junction must be removed, which is precisely the reaction of the above-mentioned parameters characteristic.   The maximum gate-source driving voltage Vgs, which is also an absolute parameter rating of the MOSFET, represents the maximum driving voltage that the MOSFET can withstand. Once the driving voltage exceeds this limit, permanent damage to the gate oxide can occur even in a very short period of time. Generally speaking, as long as the driving voltage does not exceed the limit, there will be no problem. However, due to the existence of parasitic parameters in some special cases, the Vgs will be affected unpredictably, which needs to be paid more attention to. SOA (safe work area), each MOSFET will give its safe working area. For example, different bipolar transistors, power MOSFET does not show a second breakdown, so the safe operation area is simply defined from the dissipative power that causes the junction temperature to reach the maximum allowable value.      II. MOSFET Selection   After understanding the principle of MOSFET selection, You can select the correct MOSFET with the following four steps.   1) channel selection The first step in choosing the right device for design is to decide whether to use N-channel or P-channel MOSFET. In typical power applications, when a MOSFET is grounded and the load is connected to the trunk voltage, the MOSFET forms a low-voltage side switch. N-channel MOSFET should be used in the low-voltage side switch, which is due to the voltage required by switching on or switching off the device. When the MOSFET is connected to the bus and the load is grounded, the high-voltage side switch is used. P-channel MOSFET is usually used in this case, which is also due to the consideration of driving voltage.   2) selection of voltage and current The higher the rated voltage, the higher the cost of the device. According to practical experience, the rated voltage should be greater than trunk voltage or bus voltage. This will provide sufficient protection so that the MOSFET can work well. As far as MOSFET is concerned, it is necessary to determine the maximum possible voltage between the drain and the source. Other safety factors that design engineers need to consider include voltage transients induced by switchgear, such as motors or transformers. And rated voltages vary from application to application, typically, portable devices are 20V, FPGA power supplies are 20V~30V, and so on.　   In the continuous conduction state, the MOSFET is stable and the current passes through the device continuously. A pulse spike refers to a large number of surge current (or peak current) flowing through the device. Once the maximum current is determined under these conditions, simply select the device that can withstand the maximum current.   3) calculating on-loss The power loss of MOSFET devices can be calculated by Iload2×RDS (on). Because the on-resistance varies with temperature, the power loss also varies proportionally. For portable designs, lower voltages are more common, and for industrial designs, higher voltages can be used. Note that the RDS (on) resistance increases slightly with the current. Variations in the electrical parameters of the RDS (on) resistance can be found in the technical datasheet provided by the manufacturer.   4) heat dissipation requirements for a computing system　 The designer must consider two different situations, the worst case, and the real situation. It is recommended that the worst-case results be used because the results provide a greater security margin to ensure that the system does not fail. There are also some measurements on the MOSFET table that need to be noticed, such as the thermal resistance between the semiconductor junction and the environment of the packaged device, and the maximum junction temperature.   Switching loss is also a very important indicator. The voltage-current product of the on-off moment is quite large, which determines the switching performance of the device to a certain extent. However, if the system requires high switching performance, you can choose a power MOSFET with a lower gate charge.     III. MOSFET Gate Material   Theoretically, the gate of MOSFET should be chosen as well as possible, and the conductivity of polysilicon doped by heavy can be used on the gate of MOSFET.    The reasons for using polysilicon in MOSFETs are as follows:    1) The threshold voltage of the MOSFET is mainly determined by the difference between the work function of the gate and the channel material, and because the polysilicon is essentially a semiconductor, it is possible to change its work function by doping impurities of different polarities. More importantly, since the gap between the polysilicon and the silicon as the channel is the same, it is possible to achieve the demand by directly adjusting the work function of the polysilicon when the threshold voltage of the PMOS or NMOS is reduced. Conversely, the work function of the metallic material is not like the semiconductor is then easily changed so that it becomes difficult to reduce the critical voltage of the MOSFET. And if the threshold voltage of the PMOS and the NMOS is to be reduced at the same time, two different metals are required to do their gate material, respectively, and a large variable for the producing process.   2) After years of research on the silicon-silica interface, it has been proved that the defect between the two materials is relatively small. On the contrary, there are many defects in the metal-insulator interface, so it is easy to form a lot of surface energy levels between the two, which greatly affects the characteristics of the elements.   3) The melting point of the polycrystalline silicon is higher than most of the metal, while in the modern semiconductor process, the gate material is used to deposit the gate material at high temperatures to improve the efficiency of the element. The low melting point of the metal will affect the upper-temperature limit that can be used by the process.   However, although polysilicon has been the standard material for the manufacture of MOSFET gates, there are also a number of shortcomings of it, which makes it possible for some MOSFET to use metal gates in the future.    These shortcomings are as follows:   (1) Polysilicon is less conductive than metal, limiting the speed of signal transmission. Although doping can be used to improve its conductivity, the effectiveness is still limited. Some metal materials with a high melting point, such as tungsten, titanium, cobalt, or nickel, are used to make alloys with polysilicon. This type of mixture is commonly referred to as metal silicide. The polysilicon gate with metal silicide has good electrical conductivity and can withstand a high-temperature process. In addition, because the position of the metal silicide is on the surface of the grid, therefore, the critical voltage of MOSFET will not be affected much.   The process of plating a metal silicide on the gate, source, and drain is referred to as self-aligned metal, commonly referred to as salicide process.   (2) When the size of the MOSFET is small and the gate oxide layer also becomes very thin, for example, the new process can reduce the oxide layer to a thickness of about one nanometer, and a phenomenon is also generated unprecedentedly, and that is "polysilicon depletion". When the inversion layer of the MOSFET is formed, the MOSFET gate polysilicon depletion phenomenon is occurring close to the oxide layer, and a depletion layer is present to influence the conduction characteristics of the MOSFET. To address this problem, one way is the metal gate. Reasonable materials include tantalum, tungsten, tantalum nitride, or titanlium nitride. The gates made by these metals usually form MOS capacitors along with oxide formed by high permittivity substances. Another solution is the polysilicon alloying, also called FUSI (FUlly-SIlicide polysilicon gate).   IV. MOSFET Advantage   MOSFET was first made successfully in 1960 by D. Kahng and Martin Atalla in Bell Labs, and the operating principle of this element was very different from that of the bipolar junction transistor (BJT) invented by William Shockley in 1947. And because of the low cost and small size, it plays a very important role in large-scale integrated circuits (LSI) and very large-scale integrated circuits (VLSI) than BJT.   1) Field-effect transistor (FET) is a voltage control element, and bipolar junction transistor (BJT) is a current control element. The FET should be selected when only less current is allowed, and the BJT should be chosen when the signal voltage is low and more current is allowed to flow through from the source of the signal.   2) The source and drain poles of some FET can be used interchangeably, the gate voltage can also be positive and negative, and the flexibility is better than the bipolar transistor.   3) FET is called a monopole device because it makes use of majority carriers to conduct electricity, while BJT is conducting by majority carrier or minority carrier, therefore, it is called bipolar device.   4) FET can work under the conditions of very low current and low voltage, and its manufacturing process can easily integrate many FETs on a silicon wafer. Therefore, FET has been widely used in large-scale integrated circuits (LSI).   With the improvement of the performance of MOSFET components, except the traditional applications in digital signal processing such as microprocessors and microcontrollers, more and more integrated circuits for analog signal processing can be implemented by MOSFET.   V. MOSFET Technology   1) Dual-gate MOSFET Dual-gate MOSFET is usually used in radio frequency (RF) integrated circuits. The two gates of the MOSFET can control the current. In RF circuits, the second gate of the dual-gate MOSFET is mostly used for gain, mixer, or frequency conversion control.   2) Depletion Type MOSFET In general, a depletion-mode MOSFET is less common than the enhancement mode MOSFET. The depletion-mode MOSFET changes the impurity concentration of the channel in the doping process so that the channel still exists even if the gate of the MOSFET is not applied voltage. If you want to close the channel, you must apply a negative voltage to the gate. Thus the most application of the depleted MOSFETs is in the "normally-off" switch, while the enhancement-mode MOSFET is usually used in the " normally-on" switch.   3) NMOS Logic The NMOS of the same driving capability is generally smaller than the area occupied by the PMOS, and therefore, if an NMOS is used only on the design of the logic gate, the chip area itself can be reduced. However, although the area of the NMOS logic is small, the static power will be consumed unlike the CMOS logic, so it has gradually exited the market after the mid-1980s.   4) Power MOSFET There is a significant structural difference between the power MOSFET and the above-mentioned MOSFET elements. In general, MOSFET in integrated circuits are planar structures, and the endpoints of transistors are only a few microns away from the surface of the chip. But all the power components are vertical structures, which allows the components to withstand both high voltage and high current working environments. A power MOSFET withstand voltage is a function of the doping concentration and the thickness of the N-type epitaxial layer, and the width of the channel is related to how much the current can pass through, that is, the wider channel can accommodate more current. For a planar MOSFET, the current and the breakdown voltage are dependent on the length and width of the channel. For a vertical MOSFET, the area of the element is approximately proportional to the current it can hold, and the thickness of the epitaxial layer is proportional to its breakdown voltage.   Working principle Due to the positive power supply between the source and the drain, the voltage between them is zero. The PN junction J1 formed between the P base region and the N drift region is anti-biased, and no current flows between the source and the drain.   Conduction: the positive voltage UGS, the gate is insulated between the gate and the source, so there will be no gate current flowing through. However, when the positive voltage of the gate pushes the hole in the P region below it and attracts the minority electron in the P region to the surface of the P region below the gate and the UGS is greater than the UT (on voltage or threshold voltage), the electron concentration on the surface of the P region under the gate will exceed the hole concentration, which causes the P-type semiconductor inversion to become N-type and becomes the inversion layer. The inversion layer forms N-channel and makes the PN junction J1 disappear, and the drain and the source turn to conductive.   It is worth mentioning that power MOSFET with planar structure is not non-existent, and this kind of element is mainly used in advanced sound amplifiers. The characteristics of planar power MOSFET in the saturation region are better than that of vertical structure MOSFET. Vertical power MOSFET takes the advantage of very small turn-on resistance and is mostly used for switches.   5) DMOS DMOS is an abbreviation for a double-diffused MOSFET, which is mainly used for high voltage and belongs to the category of high-voltage MOSFET.   The MOSFET is used to realize the analog switch. The channel resistance of the MOSFET is low when the MOSFET is turned on, and the resistance is almost infinite when the MOSFET is turned off so that the switch which is suitable as a switch of the analog signal (the energy of the signal is not lost due to the resistance of the switch). When the MOSFET is a switch, its source and drain are different from each other, respectively, because the signal can be accessed from any end of the MOSFET. For an NMOS switch, the negative voltage is in the source, it opposite to the PMOS, the positive voltage is in the source. The signal that the MOSFET switch can transmit is subject to its voltage between gate and source, gate and drain, drain and source. If the upper limit of the voltage is exceeded, the MOSFET may burn out.   MOSFET switches have a wide range of applications, such as the need for sampling holding circuit (sample-and-hold circuits) or truncated circuit (chopper circuits) design, For example, MOSFET switch can be seen on the analog-digital converter (A / D converter) or switched capacitor filter (switch-capacitor filter).   6) Single MOSFET Switch When the NMOS is used as a switch, the base is grounded and the gate is the controlling end of the switch. The state of the switch is on when the gate voltage subtracts the source voltage exceeding the critical voltage. If the gate voltage continues to rise, the current through which the NMOS can pass more. NMOs operate in the linear region when the switch is turned on because the voltage of the source and drain tends to be consistent when the switch is on.   When the PMOS is used as a switch, its base is connected to the highest potential in the circuit, usually a power supply. The voltage of the gate is very low than the source. And when the gate exceeds the critical voltage, the PMOS switch will be turned on.   And a single MOSFET switch may reduce the amplitude of the signal and distort the signal.   7) Double MOSFET (CMOS) Switch In order to improve the signal distortion caused by the single MOSFET switch mentioned above, the use of a PMOS plus and an NMOS of CMOS switch has become the most common practice at present. The PMOS switch connects the source and drain of the NMOS separately. The basic joining rule is the same as the traditional connecting method of NMOS and PMOS. When the input voltage is at (VDD-Vthn) and (VSS+Vthp), the PMOS and NMOS are on, but when the input is less than (VSS+Vthp), only NMOS is on and the input is greater than (VDD-Vthn), and only the PMOS turns on. The advantage of this is that under most of the input voltage, both the PMOS and the NMOS are turned on at the same time, and if the on-resistance of either side is increased, the on-resistance on the other side is reduced, so that the resistance of the switch can be kept almost constant, thus the signal distortion is reduced.   Fig. 8 switching process of power MOSFET   VI. Common MOSFET Failures     Overvoltage damage, including gate overvoltage and drain overvoltage, often accompanied by overcurrent. If protection happened in a very short period of time, it may be overvoltage damage. If there is no overvoltage protection and the state turns into overcurrent damage, the chip in the source non-line region will burn out.   A large current, such as severe over-current short-circuit damage, will cause a large amount of heat to burn out the chip.   Overheat damage, if the MOS tube isn’t appearing overcurrent and overvoltage, just because the junction temperature is too high, if the chip is protected, the surface will not see obvious burns, if not, there will be a large amount of burning area.   In general, the mechanism of MOS tube damage is usually thermal damage, local overheating, or overall heating, such as overvoltage, is a crystal package that can’t stand high voltage breakdown causing heating damage.   The fault analysis of the MOS tube should be based on the combination of specific circuit and burning phenomenon to be more accurate. Fig. 9 basic structure of an n-channel mosfet     VII. MOSFET's Well-Known Brands   MOSFETs are mainly divided into several series: American, Japanese, Korean, Taiwan, and so on. The brand's representatives of each system are as follows:   American: IR ST TI PI Fairchild Infineon ON Semiconductor Japanese: TOSHIBA RENESAS SHINDENGEN Taiwan: APEC CET Korean: KEC AUK MagnaChip KIA Truesemi Wisdom   FAQ 1. What is Mosfet and how it works? In general, the MOSFET works as a switch, the MOSFET controls the voltage and current flow between the source and drain. The working of the MOSFET depends on the MOS capacitor, which is the semiconductor surface below the oxide layers between the source and drain terminal.   2. What is Mosfet and its characteristics? MOSFETs are tri-terminal, unipolar, voltage-controlled, high input impedance devices which form an integral part of vast variety of electronic circuits. ... In this region, MOSFET behaves like an open switch and is thus used when they are required to function as electronic switches.   3. How many types of Mosfet are there? Four types. There are two classes of MOSFETs. There is depletion mode and there is enhancement mode. Each class is available as n- or a p-channel, giving a total of four types of MOSFETs.   4. What is an ideal Mosfet? In an ideal MOSFET, setting the gate-source voltage to a value VGS < VTn places the transistor into cutoff with ID = O. Increasing the gate-source voltage to a value VGS > VTn allows the transistor to conduct current ID; this defines the active mode of operation. 5. How do I know if my MosFet is bad? A good MOSFET should have a reading of 0.4V to 0.9V (depends on the MOSFET type). If the reading is zero, the MOSFET is defective and when the reading is “open” or no reading, the MOSFET is also defective. When you reverse the DMM probe connections, the reading should be “open” or no reading for a good MOSFET.   6. What is a Mosfet used for? What is a MOSFET and How does it work? MOSFET, in short, is a metal oxide semiconductor field-effect transistor used to switch or amplify voltages in circuits. Being part of the field-effect transistor family, it is a current-controlled device that is constructed with 3 terminals.   7. Is Mosfet still used? The MOSFET is by far the most widely used transistor in both digital circuits and analog circuits, and it is the backbone of modern electronics. It is the basis for numerous modern technologies, and is commonly used for a wide range of applications.   8. Why is it called Mosfet? The source is so named because it is the source of the charge carriers (electrons for n-channel, holes for p-channel) that flow through the channel; similarly, the drain is where the charge carriers leave the channel.   9. What causes a Mosfet to fail? If the maximum operating voltage of a MOSFET is exceeded, it goes into Avalanche breakdown. ... If the energy contained in the transient over-voltage is above the rated Avalanche energy level, then the MOSFET will fail. The device fails short circuit, initially, with no externally visible signs.   10. Why N channel is better than P channel Mosfet? N-Channel MOSFETs are more efficient than P-Channel MOSFETs.It comes down to physics. N-Channel MOSFETs use electron flow as the charge carrier. P-Channel MOSFETs use hole flow as the charge carrier, which has less mobility than electron flow. And therefore, they have higher resistance and are less efficient.   You May Also Like Selection of Drive Resistor: MOSFET | Gate Drive Reference Component KY56-SQ7415AEN-T1_GE3 KY56-STP160N3LL