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Catalog Overview       Structure and Working Principle of Power   MOSFET Structure of Power MOSFET WorkingPrinciple of Power MOSFET   Basic Characteristics of Power MOSFET Static Properties Dynamic Characteristics Switching Speed of MOSFET Improvement of Dynamic Performance                   Principle and Performance Analysis of High Voltage MOSFET Principle and Method of Reducing on Resistance of High Voltage MOSFET On-Resistance Distribution of MOSFET with Different Voltage Resistance The Idea of Reducing the On-Resistance of High Voltage MOSFET     Main Characteristics of Built-In Transverse Electric Field MOSFET The Decrease of On-Resistance The Reduction of Package and the Reduction of Thermal Resistance Improvement of Switching Characteristics Anti-Avalanche Breakdown Ability and SCSOA Development Status of Built-in Transverse Electric Field High Voltage MOSFET Comparison Between COOLMOS and IGBT Power MOSFET Drive Circuit Introduction and Analysis of Several MOSFET Drive Circuits An Unisolated Complementary Drive Circuit Isolated Drive Circuit   1. Overview The original meaning of MOSFET is Metal-Oxide-Semiconductor Field-Effect-Transistor. MOS means that the gate of the metal layer (M) is separated by the oxide layer (O) to control the field effect transistor of the semiconductor (S) by the effect of electric field. Power field effect transistors are divided into junction type and insulated gate type, but it usually refers to the MOS type（Metal Oxide Semiconductor FET） in the insulation grid type, which is referred to as power MOSFET. Junction power field effect transistors are generally referred to as Static Induction Transistor (SIT). It is characterized in that the gate voltage is used to control the drain current, the drive circuit is simple, the drive power is small, the switching speed is fast, the working frequency is high, and the thermal stability is better than that of GTR. However, its current capacity is small and it can just withstand low voltage. Generally speaking, it is only suitable for power electronic devices whose power does not exceed 10kW.   2. Structure and working principle of Power MOSFET Types of Power MOSFET: According to the conductive channel, it can be divided into P channel and N channel.  According to the amplitude of gate voltage, it can be divided into: depletion type and enhancement type. Power MOSFET is mainly N-channel enhancement type.   2.1 Structure of Power MOSFET The internal structure and electrical symbols of the power MOSFET are shown in figure 1. When a monopole transistor is turned on, only one polar carrier (multiple carriers) is involved in the conduction. The conductive mechanism is the same as that of the low power MOSFET, but the structure is quite different. The low power MOSFET is a transverse conductive device. The power MOSFET mostly adopts the vertical conductive structure, also known as VMOSFET (Vertical MOSFET), which greatly improves the voltage and current resistance of MOSFET devices. Fig 1.   According to the difference of vertical conductive structure, it can be divided into two types. One is VVMOSFET, which use V-shaped slot to achieve vertical conduction. Another is VDMOSFET (Vertical Double-diffused MOSFET), which has vertical conductive double diffusion MOS structure. In this article, VDMOS devices are discussed as an example.  The power MOSFET is a multivariate integrated structure, such as the hexagonal unit adopted by the HEXFET of International Rectifier, the square unit adopted by the SIPMOSFET of Siemens and rectangular unit adopted by TMOS of Motorola.   2.2 Working principle of Power MOSFET Cut-off: Positive power supply is added between drain and source, and the voltage between gate and source is zero. The J1 of the PN junction formed between the P base region P and the drift region N is inversely biased, and there is no current flow between the drain and source.  Conduction: By adding a positive voltage UGS between the gate sources, the gate is insulated, so no gate current flows through it. However, the positive voltage of the gate pushes away the holes in the region P below it, and attracts the electrons, minority carrier in the region P to the surface of the region P below the gate.  When the UGS is greater than the UT (turn-on voltage or threshold voltage), the electron concentration on the surface of the region P under the gate will exceed the hole concentration, making the P-type semiconductor inverse into the N-type and become the inversion layer. The inversion layer forms the N channel and makes the PN junction J1 disappear. The drain and source conduct electricity.   2.3 Basic characteristics of Power MOSFET  2.3.1 Static properties: the transfer and output properties are shown in figure 2. Fig 2. The relationship between drain current ID and gate source voltage UGS is called the transfer characteristic of MOSFET. When the ID is large, the relationship between ID and UGS is approximately linear, and the slope of the curve is defined as transconductance Gfs.  The drain volt-ampere characteristics (output characteristics) of MOSFET are as follows: Cutoff region (corresponding to the cutoff region of GTR) Saturation region (corresponding to the magnification region of GTR) Unsaturated region (corresponding to the saturation region of GTR)  The power MOSFET works in the switching state, which means that it switches back and forth between the cut-off zone and the unsaturated zone. There is a parasitic diode between the drain and source of power MOSFET, and the device is turned on when the reverse voltage is applied between the drain and source. The on-state resistance of power MOSFET has a positive temperature coefficient, which is beneficial to the current sharing of the devices connected in parallel.   2.3.2 Dynamic characteristics; the test circuit and switching process waveforms are shown in figure 3 Fig 3. 2.3.3 Switching Speed of MOSFET The switching speed of MOSFET has a lot to do with the charge and discharge of Cin. The user can not reduce the Cin, but can reduce the internal resistance of the drive circuit Rs, reduce the time constant and speeds up the switching speed. MOSFET only depends on multiple carriers to conduct electricity, and there is no minority carrier storage effect, so the turn-off process is very fast. The switching time is between 10-100ns, and the working frequency can reach more than 100kHz, which is the highest among the main power electronic devices. When the field control device is static, there is little need for input current. However, during the process of switching, the input capacitor needs to be charged and discharged, and a certain amount of drive power is still needed. The higher the switching frequency, the greater the drive power required.   2.4 Improvement of dynamic performance In the application of the device, in addition to considering the voltage, current and frequency of the device, we must also grasp how to protect the device in the application so as not to damage the device in the transient change. Of course, the thyristor is a combination of two bipolar transistors, coupled with the large capacitance brought by large area, so its dv/dt capability is relatively fragile. For di/dt, it also has a conduction zone extension problem, so it also brings quite strict restrictions. The case of power MOSFET is very different. Its dv/dt and di/dt capabilities are often measured by its ability per nanosecond rather than per microsecond. But in spite of this, it also has the limitation of dynamic performance. These can be understood from the basic structure of power MOSFET.  Fig. 4 is the structure of the power MOSFET and its corresponding equivalent circuit. In addition to the fact that almost every part of the device has a capacitance, it must also be considered that the MOSFET is connected in parallel with a diode. At the same time, from a certain point of view, it also has a parasitic transistor, just as IGBT is parasitic on a thyristor. These aspects are very important factors to study the dynamic characteristics of MOSFET. Fig 4. First of all, the intrinsic diode attached to the MOSFET structure has certain avalanche ability. It is usually expressed as the ability of a single avalanche and the ability of repeated avalanche. When the reverse di/dt is very large, the diode will withstand a very fast pulse spike. It may enter the avalanche area, once its avalanche capacity is exceeded, the device may be damaged. As any kind of PN junction diode, it is very complex to study its dynamic characteristics carefully. They are very different from the simple concept that we generally understand that the PN junction is conducted when it is forward and blocked when it is backward. When the current drops rapidly, the diode loses its reverse blocking ability and this is the so-called backward recovery time. When the PN junction requires rapid conduction, there will be a period of time when the resistance is not very low. Once the diode has a positive injection in the power MOSFET, the injected minority carriers will also increase the complexity of the MOSFET as a multi-subdevice.  During the design process of power MOSFET, measures are taken to make the parasitic transistors as ineffective as possible. The measures are different in different generation of power MOSFET, but the general principle is to make the transverse resistance RB under the drain as small as possible. Because only when the transverse resistance under the region N of drain flows through enough current to establish the positive deviation condition for the region N, the parasitic bipolar thyristor begins to cause difficulties. However, under severe dynamic conditions, the transverse current caused by dv/dt through the corresponding capacitance may be large enough. At this point, the parasitic bipolar transistor will start, possibly causing damage to the MOSFET. Therefore, when considering the transient performance, attention must be paid to the internal capacitance of the power MOSFET device, which is the channel of the dv/dt.  The transient situation is closely related to the line condition, which should be paid enough attention in the application. In order to understand and analyze the corresponding problems, it is necessary to have an in-depth understanding of the device.   3. Principle and Performance Analysis of High Voltage MOSFET In power semiconductor devices, MOSFET plays an important role in all kinds of power conversion, especially in high frequency power conversion with high speed, low switching loss and low drive loss. In the low voltage field, MOSFET has no competitors, but with the increase of the voltage resistance of MOS, the on-resistance increases to the power of 2.4 to 2.6. The growth rate makes MOSFET manufacturers and users have to reduce the rated current by tens of times in order to compromise the contradiction between rated current, on resistance and cost. Even so, the on-voltage drop caused by the on-resistance of the high-voltage MOSFET at the rated junction temperature is still high. The rated junction temperature and current of the MOSFET withstanding voltage above 500V are very high, and the on-voltage above 800V is astonishingly high. The conduction loss accounts for two-thirds to four-fifths of the total loss of MOSFET, which greatly limits the application.   3.1 Principle and Method of Reducing on Resistance of High Voltage MOSFET  3.1.1 On-resistance distribution of MOSFET with different voltage resistance: The resistance proportional distribution of each part of the on-resistance of MOSFET with different voltage resistance is also different. For example, the epitaxial layer resistance of 30V MOSFET is only 29% of the total on resistance, and the epitaxial layer resistance of 600V MOSFET is 96.5% of the total on resistance. From this, it can be inferred that the on-resistance of 800V MOSFET will be almost occupied by the epitaxial layer resistance. In order to obtain high blocking voltage, the epitaxial layer with high resistivity must be used and thickened. This is the fundamental reason for the high on resistance caused by the conventional high voltage MOSFET structure.   3.1.2 The Idea of Reducing the On-Resistance of High Voltage MOSFET　　 Increasing the core area can reduce the on-resistance, but the cost is not allowed by commercial products. Although the introduction of minority carrier for conducting electricity can reduce the conduction voltage drop, but the price is the decrease of switching speed and the appearance of trailing current, the increase of switching loss and the loss of the high speed advantage of MOSFET. The above two methods can not reduce the on-resistance of high voltage MOSFET, the remaining idea is how to separately solve the low doping of high voltage, high resistivity region and the high doping, low resistivity of conductive channel. For example, it has no other use except that the high voltage epitaxial layer low doping can only increase the on resistance. In this way, whether we can realize the conductive channel with high doping and low resistivity, and try to clamp the channel in some way when the MOSFET is turned off, so that the voltage withstand of the whole device depends only on the low doping N-epitaxial layer. Based on this idea, INFINEON introduced a built-in transverse electric field voltage of 600V COOLMOS in 1988 to realize this idea. The profile structure of the high voltage MOSFET with built-in transverse electric field and the schematic diagram of high blocking voltage and low on resistance are shown in figure 5. Different from the conventional MOSFET structure, the MOSFET with the built-in transverse electric field embeds the vertical region P and clamps the region N of the vertical conductive region in the middle, so that when the MOSFET is turned off, the transverse electric field is established between the vertical P and N. The N doping concentration in the vertical conductive region is higher than that in the epitaxial region. When VGS is less than VTH, the N-type conductive channel caused by the inversion of electric field cannot be formed, and the positive voltage between D and S makes the PN junction inside MOSFET backward bias to form a depletion layer and the vertically conductive region N is exhausted. This depletion layer has a longitudinal high blocking voltage, as shown in figure 5 (b), where the voltage resistance of the device depends on the voltage resistance of P and N-. Therefore, low doping and high resistivity of N-are necessary. Fig 5. When CGS is greater than VTH, the N-type conductive channel is formed by the inversion of electric field. The electrons in the source region enter the exhausted vertical region N to neutralize positive charge through the conductive channel, thereby restoring the exhausted N-type characteristics, so the conductive channel is formed. Because of the low resistivity in the vertical region N, the on-resistance will be significantly lower than that of the conventional MOSFET. Through the above analysis, we can see that the blocking voltage and on-resistance are in different functional areas. The contradiction between the blocking voltage and the on-resistance is solved by separating the blocking voltage from the on-resistance function. At the same time, the surface PN junction is transformed into a buried PN junction, and the blocking voltage can be further increased at the same N-doping concentration.   3.2 Main Characteristics of Built-in Transverse Electric Field MOSFET 3.2.1 The decrease of on-resistance The MOSFET of the built-in transverse electric field of the INFINEON withstands 600V and 800V respectively. Compared with conventional MOSFET devices, the on-resistance with the same core area decreases to one fifth and one tenth of conventional MOSFET, and the on-resistance decreases to one second and one third respectively at the same rated current. Under the conditions of rated junction temperature and rated current, the conduction voltage is reduced from 12.6V, 19.1V to 6.07V, 7.5V, and the conduction loss is reduced to one second and one third of conventional MOSFET, respectively. Because of the decrease of conduction loss, the decrease of heat and the relative coolness of the device, it is called COOLMOS.   3.2.2 The reduction of package and the reduction of thermal resistance Compared with the conventional MOSFET, the core of the COOLMOS with the same rated current is reduced to one third and one fourth, which reduces the package by two shell specifications. Because the thickness of COOLMOS core is only one third of that of conventional MOSFET, the RTHJC of TO-220 package is reduced from 1 ℃ / W to 0.6 ℃ / W, and the rated power is increased from 125W to 208W, which improves the heat dissipation capacity of the core.   3.2.3 Improvement of switching characteristics　　 The gate charge and switching parameters of COOLMOS are obviously better than those of conventional MOSFET. Due to the decrease of QG, especially QGD, the switching time of COOLMOS is about one second of that of conventional MOSFET, and the switching loss is reduced by about 50%. The decrease of turn-off time is also related to the low gate resistance in COOLMOS.   3.2.4 Anti-avalanche breakdown ability and SCSOA At present, the new MOSFET has the ability to resist avalanche breakdown without exception. COOLMOS also has the ability to resist avalanche. At the same rated current, the IAS of COOLMOS is the same as ID25 ℃. However, because of the decrease of the core area, when the IAS is smaller than the conventional MOSFET, and has the same core area, the IAS and EAS are larger than the conventional MOSFET. One of the biggest features of COOLMOS is that it has a short circuit safe operation area (SCSOA), but the conventional MOS does not have this feature. The SCSOA of COOLMOS is mainly due to the change of transfer characteristics and the decrease of core thermal resistance. The transfer characteristics of COOLMOS are shown in figure 6. As we can see from figure 6, when VGS is greater than 8V, the drain current of COOLMOS no longer increases, showing a constant current state. Especially when the junction temperature increases, the constant current value decreases, and at the highest junction temperature, it is about twice as much as ID25 ℃, that is, 3 to 3.5 times of the normal working current. In the short circuit state, the drain current will not rise to an intolerable ID25 ℃ due to the 15V drive voltage of the gate, so that the power dissipated by the COOLMOS in the short circuit is limited to 350V × 2ID25 ℃, so as to reduce the core heat during the short circuit as much as possible. The decrease of the thermal resistance of the core can make the heat generated by the core radiate quickly to the shell and restrain the rising rate of the core temperature. Therefore, COOLMOS can be driven by normal gate voltage, withstand 10 MS short circuit shock under 0.6VDSS power supply voltage for 1000 times without damage and the time interval is greater than 1s. Therefore, COOLMOS can be protected effectively in short circuit like IGBT. Fig 6. 3.3 Development Status of Built-in Transverse Electric Field High Voltage MOSFET Following the introduction of COOLMOS in 1988, ST introduced 500V internal structure similar to COOLMOS in early 2000, so that 500V, 12A MOSFET can be packaged in TO-220 shell, the on-resistance is 0.35 Ω, which is lower than that of IRFP450, and the current rating is similar to that of IRFP450. IXYS also has MOSFET that uses COOLMOS technology. IR also introduced the super MOSFET, rated current of 35A and 59A in SUPPER220, SUPPER247 package, and the on-voltage drop of about 4.7V when the on-resistance is 0.082 Ω, 0.045 Ω and 150C, respectively. From the comprehensive index, these MOSFET are superior to the conventional MOSFET. The proportional decrease of on resistance is not due to the increase of core area. Therefore, it can be considered that the above MOSFET must have a special structure similar to the transverse electric field. It can be seen that trying to reduce the conduction pressure drop of high pressure MOSFET has become a reality, and will promote the application of high voltage MOSFET.   3.4 Comparison between COOLMOS and IGBT The high temperature conduction voltage drop of 600V and 800V COOLMOS is about 6V and 7.5V respectively, the turn-off loss is reduced by one second, and the total loss is reduced by more than one second, so that the total loss is 40% to 50% of that of conventional MOSFET. The conduction loss of the conventional 600V MOSFET accounts for about 75% of the total loss, and the equilibrium point corresponding to the same total loss and ultra-high speed IGBT is 160KHZ, of which the switching loss accounts for about 75%. Because the total loss of COOLMOS is reduced to 40% to 50% of that of conventional MOSFET, the corresponding IGBT loss balance frequency will be reduced from 160KHZ to about 40KHZ, which increases the application of MOSFET in high voltage. From the above discussion, it can be seen that the new high voltage MOSFET solves the problem of high conduction voltage drop, and can simplify the design of the whole machine, such as the volume of heat dissipation device can be reduced to about 40%, drive circuit and buffer circuit are simplified. It has the ability to resist avalanche breakdown and short circuit, simplify the protection circuit and improve the reliability of the whole machine.   4. Power MOSFET drive circuit Power MOSFET is a voltage type driver. Because there is no minority carrier storage effect, the input impedance is high, the switching speed can be very high, the drive power is small, and the circuit is simple. However, the interpolar capacitance of the power MOSFET is large, and the relationship between the input capacitance CISS, the output capacitance COSS, the feedback capacitance CRSS and the interpolar capacitance can be expressed as follows: The gate input of the power MOSFET is equivalent to a capacitive network, and its working speed is related to the internal impedance of the drive source. Due to the existence of CISS, the gate drive current is almost zero in static state, but a certain drive current is still needed in the dynamic process of turning on and off. It is assumed that the gate voltage required for saturation conduction of the switch tube is VGS, the turn-on time TON of the switch includes two parts: the turn-on delay time TD and the rise time TR.   During the turn-off process of the switch tube, CISS is discharged through ROFF, COSS is charged by RL, COSS is larger, VDS(T) rises slowly. With the increase of VDS(T), COSS decreases rapidly to close to zero, and VDS(T) increases rapidly. According to the above analysis of the characteristics of the power MOSFET, the drive requirements are as follows: The trigger pulse should have a fast enough rise and fall speed;   Charging with low resistance gate capacitance when turned on, and providing low resistance discharge circuit for gate when turned off in order to improve the switching speed of power MOSFET;  In order to enable the power MOSFET to turn on by trigger, the trigger pulse voltage should be higher than the opening voltage of the tube. In order to prevent misconduction, a negative gate source voltage should be provided at its cut-off time; When the power switch switches, the drive current is the charge and discharge current of the gate capacitance. The larger the interelectrode capacitance of the power tube is, the greater the required current is, that is, the greater the load capacity is.   4.1 Introduction and Analysis of Several MOSFET Drive Circuits   4.1.1 An unisolated complementary drive circuit Figure 7 (a) is a commonly used low power drive circuit, which is simple, reliable and low cost. It is suitable for low power switchgear that does not require isolation. The drive circuit shown in figure 7 (b) has fast switching speed and strong drive capability. In order to prevent the two MOSFET tubes from going straight through, a 0.5 × 1 Ω low resistance is usually connected in series for current limiting. The circuit is suitable for medium power switchgear that does not require isolation. These two kinds of circuits are characterized by simple structure. Fig 7. Power MOSFET is a voltage type control device. As long as the voltage applied between the gate and the source exceeds its threshold voltage, it will be turned on. Because of the junction capacitance of MOSFET, the sudden rise of the voltage at both ends of the drain source will produce interference voltage at both ends of the gate source through the junction capacitance when it is turned off. The turn-off circuit of the commonly used complementary drive circuit has small impedance and fast turn-off speed, but it cannot provide negative pressure, so its anti-interference is poor. In order to improve the anti-interference of the circuit, a circuit composed of V1, V2 and R can be added to the drive circuit to produce a negative pressure. The circuit schematic diagram is shown in Fig. 8. Fig 8. When V1 is turned on, V 2 is turned off, the gate and source of the upper tube in the two MOSFET are discharged, and the gate and source of the lower tube are charged, that is, the upper tube is turned off and the lower tube is turned on, which is turned off by the driven power tube. On the contrary, when V1 is turned off, V 2 is turned on, the upper tube is turned on, and the lower tube is turned off thus to turn on the driven pipe. Because the gate and source of the upper and lower tubes are charged and discharged through different circuits, including the circuit of V 2 and because V2 will continue to exit saturation until it is turned off, it is slower for S1 to turn on than to turn off, and faster to turn on than to turn off for S2. Therefore, the degree of fever of the two tubes is not exactly the same; S1 is more serious than S2. The disadvantage of the drive circuit is that it needs double power supply, and because the value of R cannot be too large, otherwise it will make V1 deeply saturated and affect the turn-off speed. So, there will be a certain loss on R.   4.1.2 Isolated drive circuit Forward drive circuit The circuit principle is shown in figure 9 (a). N3 is demagnetizing winding and S2 is the driven power tube. R2 is a damping resistance to prevent voltage oscillation at the gate and source end of the power tube. Because the leakage sense is not required to be small, and in terms of speed, R2 is generally small, so it is ignored in the analysis. Fig 9. Its equivalent circuit diagram, as shown in figure 9 (b), is a secondary side parallel resistor R1, which is not required for pulse and used as a false load of the forward converter to eliminate the misconduction caused by output voltage oscillations during the turn-off period. At the same time, it can also be used as an energy release circuit when the power MOSFET is turned off. The conduction speed of the drive circuit is mainly related to the driven S2 gate, the equivalent input capacitance of the source, the speed of the drive signal of S1 and the current provided by S1. From the simulation and analysis, we know that the smaller the duty ratio D, the larger R1, the larger L, the smaller the magnetization current, the smaller the U1 value, the slower the turn-off speed. The circuit has the following advantages: The structure of the circuit is simple and reliable, and the isolated drive is realized;   Only a single power supply can provide positive pressure when on and negative pressure when off;   When the duty ratio is fixed, the drive circuit can have a fast switching speed through the reasonable parameter design.   The disadvantages of the circuit are as follows:　 First, because the secondary side of the isolation transformer needs a false load to prevent oscillation, so the circuit loss is large; second, when the duty ratio changes, the turn-off speed changes greatly. When the pulse width is narrow, the turn-off speed of MOSFET gate becomes slower due to the decrease of stored energy.   A complementary drive circuit with an isolation transformer As shown in figure 10, V1 and V2 are complementary, capacitance C acts as an isolated DC, and T1 is a magnetic ring or tank with high frequency and high magnetic flux. Fig 10. The voltage on the isolation transformer is (1 / D) Ui when it is on and D Ui when it is turned off. If the voltage of the main power tube S by conduction is 12 V and the original side-to-turn ratio N1/N2 of the isolation transformer is 12 / [(1 / (1) Ui], the C value can be slightly larger in order to ensure the voltage stability of GS during the conduction period. The circuit has the following advantages: The circuit structure is simple and reliable, and has the function of electrical isolation. The turn-off ability of the drive does not change when the pulse width changes;   The circuit only needs one power supply, that is, it works as a single power supply. The function of isolated capacitance C can provide a negative pressure when the driven tube is turned off, which accelerates the turn-off of the power tube and has high anti-interference ability;   However, one of the major disadvantages of the circuit is that the amplitude of the output voltage will change with the change of duty ratio. When D is small, the negative voltage is small, the anti-interference of the circuit becomes worse, and the positive voltage is higher, so we should pay attention to make its amplitude not exceed the allowable voltage of MOSFET gate. When D is greater than 0.5, the positive voltage of drive voltage is less than its negative voltage, so it should be noted that the negative voltage does not exceed the allowable voltage of MOAFET gate. Therefore, the circuit is more suitable for situations where the duty ratio is fixed or the duty ratio variation range is small or the duty ratio is less than 0.5.   Drive Circuit composed of Integrated Chip UC3724/3725 The circuit composition is shown in fig. 11. UC3724 is used to generate high frequency carrier signal, and the carrier frequency is determined by capacitance CT and resistance RT. In general, the carrier frequency is less than 600kHz, and high frequency modulation waves are generated at both ends of feet 4 and 6. After being isolated by high frequency small magnetic ring transformer, it is sent to feet 7 and 8 of UC3725 chip and modulated by UC3725 and the Drive signal is obtained. A Schottky rectifier bridge in UC3725 simultaneously rectifies the high frequency modulation waves of feet 7 and 8 into a DC voltage for drive power.Generally speaking, the higher the carrier frequency is, the shorter the drive delay time will be, but the anti-interference will become worse if it is too high. The larger the magnetization inductance of the isolation transformer is, the smaller the magnetization current, the less the UC3724 heat will be. However, with the increase of the number of turns, the influence of parasitic parameters becomes greater, and the anti-interference ability will also be weakened.According to the experimental data, it is concluded that for the signal whose switching frequency is less than 100kHz, it is better to choose (400 to 500) kHz carrier frequency, the transformer uses high magnetic conductivity such as 5K, 7K and other high frequency ring magnetic core, the original magnetization inductance is less than about 1 milligram. This kind of drive circuit is only suitable for the situation where the signal frequency is less than 100kHz. If the signal frequency relative carrier frequency is too high, the relative delay is too much, and the drive power is increased, and the heating temperature of UC3724 and UC3725 chips is higher. Therefore, the switching frequency above 100kHz can only be applied to the MOSFET with smaller pole capacitance. When switching frequency of 1kVA is less than 100kHz, it is a good drive circuit. The circuit has the following characteristics: single power supply, the control signal is isolated from the drive, and the structure is simple and small, especially suitable for the situation where the duty ratio is uncertain or the signal frequency is also changed.   Fig 11.

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 If you disassemble several electronic devices, you will discover a printed circuit board (PCB), which is a small green board with maze-like markings.So what is a PCB? These small green boards aid in the operation of electronic devices. The device would not function without them. PCBs connect all of the other components inside, allowing you to use your electronic device for its intended purpose.Despite its small size, the PCB manufacturing process is quite extensive. Whether you make your own or use a PCB manufacturer, multiple steps are required for the board's development. Because each step is critical to the overall process, let's take a closer look at the 4-layer PCB production flow. The production flow of a 4-layer PCB Catalog I Parts of printed circuit boards1.1 Features of printed circuit boards1.2 The role of printed circuit boardII PCB manufacturing processFAQ I Parts of printed circuit boards To have a thorough understanding of Printed Circuit Boards (PCBs), it is important to know the various parts that are used to make the boards.The most obvious starting point is the board itself. It is plastic, reinforced with glass. The next most obvious parts are the lines and pads that connect together. These are made of copper, and are known as ‘traces’. They conduct electricity, allowing electrical charges to be carried through the board. They are similar to wires, but are much finer, and are used to carry the electricity to the end-point (one of the various types of components within the board).  Figure 1. Essential parts of a printed circuit board Simple PCBs are single-sided, with one copper layer. These are structured with one side having all the components, while the other side had the traces. Holes are placed through the board for the circuit to be carried from the trace to the component. For many years, all boards were made in a single-sided design. By definition, double sided PCBs have traces on both sides of the board.To allow the boards to be more complex and control additional functions, multi-layer boards are used. Additional layers of board have their own set of traces and components. In developing multi-layer boards, a range of issues needed to be addressed. Firstly, it is essential that the copper connections do not cross each other, as this would compromise the path of the electrical circuit. Other factors that need to be considered are resonance and noise and capacitance.The layer set in place above the copper is called the soldermask. This is a form of insulation, ensuring that the copper traces aren’t affected by any metal that may come into contact with it. It is traditionally colored green. It is designed to have gaps that expose the copper in specific places, providing points where components can be soldered to the board. The silkscreen is a layer that is printed onto the soldermask. It is a layer where text can be printed (letters and numbers) that provide instructions for the user.A range of components can be incorporated into a PCB. Without components, the PCB is simply a conductor of electricity, with no function. Components can be grouped into two broad categories – passive (components that do not require direction) and active (components that only function when they receive current from one direction). Common components include:1. Batteries: these provide the circuit with voltage.2. Capacitators: The store electricity for later use. They are available as polarized or non-polarized.3. Diodes: allows current to pass in one direction only, blocking the other.4. Inductor: These coils store charge in a magnetic field.5. Light emitting diodes (LEDs). These light up when current flows is applied. They only allow current to flow in one direction.6. Resistors: These control the electric current as it passes through. The level of resistance provided varies based on the needs of the engineer. 7. They are made in different color codes to show the level of resistance.8. Switches: These can be open or closed, allowingor blocking current.9. Transistors: These are a form of switch that performs changes function based on the voltage passing through.10. Vias: small holes in the board that allow a signal to be passed from one side to the other 1.1 Features of printed circuit boards1. After the electronic component is encapsulated, the electrical conduction can be realized.2. It is required that there should be no current flow in the insulating part.　3. It is required that there must be current flow in the conduction part.　4. As the mechanical support for the fixation and assembly of components, it must meet the requirements of mounting components.5. There must be complete and clear recognition characters and component symbols.6. It can be fixed to the appropriate part of the machine. 1.2 The role of printed circuit boardAfter the printed circuit board is adopted in the electronic equipment, the error of manual wiring is avoided because of the consistency of the same kind of printed circuit board. And the automatic insertion or mounting, automatic soldering and automatic detection of electronic components can be realized. In a word, it ensures the quality of electronic equipment, improves the labor productivity, reduces the cost, and is convenient for maintenance.Figure 2. Printed circuit board II PCB manufacturing process Now, let's take four layers as an example to see how printed circuit boards are made.  Figure 3. Chemical clean Step 1: In order to obtain an etching pattern with good quality, it is necessary to make sure that the corrosion resistance layer is firmly combined with the substrate surface, and the substrate surface is required to be free of oxidation layer, oil pollution, dust, fingerprint and other dirt. Therefore, before coating the corrosion resistant layer, it is necessary to clean the surface of the board and make the surface of the copper foil reach a certain degree of coarsening. Core material: when you start making four layers, the inner layer (the second and the third layer) must be done first. The core material is a copper sheet composed of glass fiber and epoxy resin on the upper and lower surfaces.   Figure 4. Cut sheet →dry film lamination Step 2: In order to make the shape we need on the core material, we first paste a dry film (photoresist) on the core material. The dry film is composed of polyester film, photoinduced corrosion resistant film and polyethylene protective film. When sticking the film, the polyethylene protective film is stripped from the dry film, and then the dry film is pasted on the copper surface under the condition of heating and pressurization.  Figure 5.  Image expose→image develop Step 3: Under the irradiation of ultraviolet light, the photoinitiator absorbs the luminous energy to decompose into free groups, which in turn initiate the polymerization and crosslinking of photopolymerizable monomer. After the reaction, a high molecular structure insoluble in dilute alkali solution is formed. The polymerization reaction will continue for a period of time. In order to ensure the stability of the process, the polyester film should not be torn off immediately after exposure. It should stay for more than 15 minutes, so that the polymerization reaction can continue and the polyester film should be torn off before development. Image Develop: the active group in the unexposed part of the photosensitive film reacts with dilute alkali solution to produce a soluble substance and then it dissolves, leaving a graphic part that has been photosensitive crosslinked and solidified.  Figure 6.  Copper etch Step 4: In the production of flexible printed circuit board or printed circuit board, the copper foil is removed by chemical reaction to form the required loop pattern. The copper beneath the photoresist is preserved from etching.   Figure 7. Strip resist→post etch punch→AOI inspection→oxide Step 5: The purpose of removing the film is to remove the corrosion resistant layer retained on the surface of the etched board so that the copper foil below can be exposed. "Membrane slag" filtration and waste liquid recovery should be properly treated. If the water washing after the film removing can completely cleans the board, you can consider not doing pickling. Finally, the board should be completely dry after cleaning.   Figure 8. Lay-up with prepreg Step 6: Before entering the press machine, it is necessary to prepare the raw materials for each multilayer board for lay-up operation. In addition to the oxidized inner layer, the prepreg is also needed. The function of the lamination is to stack the boards covered with protective film in a certain order and place them between the two-layers of steel plate.  Figure 9.  Lay up with copper foil→vacuum lamination press  Step 7: Cover the current core material with a layer of copper foil on both sides, and then cool to room temperature after multi-layer pressurization, which requires temperature and pressure to be measured over a fixed period of time. And a multilayer sheet is finished.   Figure 10.  CNC drill Step 8: Under the accurate condition of inner layer, the CNC drilling machine drills according to the mode. Drilling accuracy is required to ensure that the hole is in the correct position.    Figure 11. Electroless copper Step 9: In order for the through hole to be conductive between the layers ,which means the resin and glass fiber bundles of the non-conductor part of the hole wall should be metalized), copper must be filled in the hole. The first step is to coat the hole with a thin layer of copper, which is a complete chemical reaction. The final copper plating is 1/1000000 of 50 inches thick.   Figure 12. Cut sheet→dry film lamination Step 10: Photoresist: this time we apply photoresist to the outer layer.   Figure 13. Image expose→image develop Step 11:This time we finish the outer exposure and development.   Figure 14. Copper pattern electro plating Step 12:This also becomes the secondary copper plating, the main purpose is to thicken the line copper and the through-hole copper.  Step 13:Its main purpose is to prevent etching and to protect the copper conductors covered by it from attacking during alkaline copper etching. The copper conductors include all the copper lines and the through holes interior.   Figure 15. Strip resist Step 14:We already know the purpose. All we have to do is to make the copper on the surface exposed by using chemical methods.   Figure 16.  Copper etch Step 15:We also know the purpose of etching. And the tinned part protects the copper foil below.   Figure 17. Tack dry→image expose→image develop→thermal cure solder mask Step 16:The welding resistance layer is used to expose the welding pad, that is, the green oil layer, which is actually digging holes in the green oil layer and exposing the welding pad and other places that do not need to be covered with green oil. Suitable surface features can be obtained by proper cleaning.  Figure 18. Surface finish Step 17:The process of hot air leveling solder coating (commonly known as tin spray) is to soak the printed circuit board with flux, then dip it in the molten solder. Next, pass it between the two wind knives and blow off the excess solder on the printed board with the hot compressed air in the wind knives. At the same time, the excess solder in the metal hole is eliminated, so as to obtain a bright, smooth and uniform solder coating.Gold finger (Gold Finger, or Edge Connector) is designed to use the connector insertion as an outlet for external contact with the board, so the gold finger process is required. Gold was chosen because of its superior conductivity and oxidation resistance. But because of the high cost of gold, it can only be used for gold fingers, local plating or electroless gold. FAQ 1. What is a PCB in a printer?While design of a printed circuit board (PCB) can be done internally, manufacturing is generally outsourced. This dependence often results in uncontrollable, and unexpected delays. ... It is here that desktop PCB printers are aiming to come to the rescue. 2. How much does it cost to print a PCB?In general, the cost to produce a PCB will cost between $10 and $50 per board. 3. How does a PCB printer work?A special printer called a plotted printer is used to print the design of the PCB. It produces a film that shows the details and layers of the board. When printed, there will be two ink colors used on the inside layer of the board: Clear Ink to show the non-conductive areas. 4.Why are PCB green?It is due to the solder mask, which protects the copper circuits printed on the fibre glass core to prevent short circuits, soldering errors, etc. ... The colour of the solder mask gives the board its appearance. 5. How much does custom PCB cost?At BatchPCB, a two-layer board costs $2.50 per square inch (about $0.40 per square centimeter), while a four-layer board costs $8 for the same area (about $1.24/cm2). The first step in creating a custom PCB is laying out the schematic view. 6. How do I print directly from PCB?A laser printer is used to print an image of the PCB on special “transfer paper” which is then placed on the bare copperclad board and either ironed or run through a modified laminator to transfer the image to the copper. 7. What does PCB stand for?printed circuit board. A printed circuit board, or PC board, or PCB, is a non-conductive material with conductive lines printed or etched. Electronic components are mounted on the board and the traces connect the components together to form a working circuit or assembly. 8. What is PCB made of?copper circuitry. Printed circuit boards (PCBs) are usually a flat laminated composite made from non-conductive substrate materials with layers of copper circuitry buried internally or on the external surfaces. They can be as simple as one or two layers of copper, or in high density applications they can have fifty layers or more. 9. Which type of PCB is more economical type?Aluminum-Backed PCBs. Aluminum is inexpensive, making almost 8.23% of planet's weight, and leads to most economical manufacturing process. PCBs made up of aluminum are easily recyclable and non-toxic in nature, making them as ideal source for energy conservation. 10. How do you choose a PCB material?Electrical functionality is based on PCB function, which makes it a good criterion for design-based circuit board material selection. According to function, PCBs may be classified as the following board types: High Frequency (High Speed) – These boards can accommodate frequencies in the 500MHz – 2GHz range.

LM4910LQ belonging to the Boomer series of National Semiconductors is an integrated stereo amplifier primarily intended for stereo headphone applications. The IC can be operated from 3.3V ans its can deliver 0.35mW output power into a 32 ohm load. The LM4910LQ has very low distortion ( less than 1%)   and the shutdown current is less than 1uA. This low shut down current makes it suitable for battery operated applications. The IC is so designed that there is no need of the output coupling capacitors, half supply by-pass capacitors and bootstrap capacitors. Other features of the IC are   turn ON/OFF click elimination, externally programmable gain etc. Stereo headphone amplifier LM4910LQCircuit diagram of the LM4910LQ stereo headphone amplifier is shown above.C1 and C2 are the input DC decoupling capacitors for the left and right input channels. R1 and R2 are the respective input resistors. R3 is the feed back resistor for left channel while R4 is the feed back resistor for the right channel. C3 is the power supply filter capacitor. The feedback resistors also sets the closed loop gain in conjunction with the corresponding input resistors. Notes:The IC is available only  in SMD packages and care must be taken while soldering.The circuit can be powered from anything between 2.2V to 5V DC.The load can be a 32 ohm headphone.Absolute maximum supply voltage is 6V  and anything above it will destroy the IC.A logic low voltage at the shutdown pins shut downs the IC and a logic high voltage at the same pin activates the IC. 

The integrated circuit is abbreviated as IC. As the name suggests, an integrated circuit is a circuit with a specific function that integrates a certain number of commonly used electronic components, such as resistors, capacitors, transistors, etc., and the connections between these components through a semiconductor process.Integrated circuits have the advantages of small size, light weight, fewer lead wires and soldering points, long life, high reliability, and good performance. At the same time, they have low cost and are convenient for mass production. They are not only widely used in industrial and consumer electronic equipment such as audio players, televisions, computers, and smartphones, but also in military, communications, automotive, and IoT applications. Using integrated circuits to assemble electronic equipment, the assembly density can be increased several tens to thousands of times compared to discrete transistor circuits, and the stable working time of the equipment can also be greatly improved. What is an IC, how it works, where to use them and can we even make one by ourselves.I What is an Integrated Circuit (IC)?An integrated circuit (IC), also called a microchip, chip, or microelectronic circuit, is a miniaturized electronic circuit consisting mainly of semiconductor devices and passive components manufactured on the surface of a thin substrate of semiconductor material, typically silicon. In other words, it is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material. The IC is then placed in a protective package to allow easy handling and assembly onto printed circuit boards (PCBs) and to protect the devices from damage. Integrated circuits are a cornerstone of modern electronics and have revolutionized the technology industry.Integrated circuitIntegrated circuits can be classified into thin-film integrated circuits (fabricated on the surface of a semiconductor chip) and thick-film hybrid integrated circuits (composed of independent semiconductor devices and passive components integrated onto a substrate or circuit board to form a miniaturized circuit).Integrated circuits have two main advantages over discrete transistors: cost and performance.The lower cost is due to the fact that the chip uses photolithography technology to print all the components as a unit instead of making transistors one at a time. High performance is achieved through fast switching and lower energy consumption because the components are small and close to each other. Modern ICs can contain billions of transistors in an area of just a few square millimeters. As of 2025, advanced process nodes have reached 3nm and below, with leading-edge chips containing over 100 billion transistors.There are many kinds of integrated circuits on the market. Currently, there is no uniform standard for the designation of integrated circuit models worldwide. Each manufacturer names integrated circuits according to its own method. In general, many IC manufacturers place the acronyms of their company names or company product codes at the beginning of the model, followed by device number, package form, and working temperature range.II What are IC Packaging and Common Types?2.1 What is IC Packaging?IC packaging refers to connecting the circuit pads on the silicon chip to external pins using bond wires or other interconnection methods to enable connection with other devices.The package form refers to the housing for mounting semiconductor integrated circuit chips. It not only plays the role of mounting, fixing, sealing, and protecting the chip and enhancing electro-thermal performance, but also connects the chip contacts to the package shell pins through bond wires or flip-chip bumps. These pins then connect via traces on the printed circuit board to other devices, realizing the connection between the internal chip and external circuits.The chip must be isolated from the outside environment to prevent impurities in the air from corroding the chip circuit and causing electrical performance degradation.2.2 What are Common IC Packaging Types?1. BGA (Ball Grid Array)The ball grid array is one of the surface mount packages. Spherical solder balls are manufactured in an array pattern on the bottom surface of the package substrate. An LSI chip is assembled on the top surface of the substrate, and then molding resin or potting methods are used for encapsulation. It is also referred to as a Pad Array Carrier (PAC). The pin count can exceed 200 and is suitable for LSI packages. The package body can also be made smaller than QFP (Quad Flat Package). BGA packages are used to permanently mount devices such as microprocessors. A BGA can provide more interconnection pins than can be accommodated on a dual in-line or flat package.The following are series of the BGA family:AcronymFull NameFBGAFine-pitch Ball Grid ArrayLBGALow-profile Ball Grid ArrayTEPBGAThermally-Enhanced Plastic Ball Grid ArrayCBGACeramic Ball Grid ArrayOBGAOrganic Ball Grid ArrayTFBGAThin Fine-pitch Ball Grid ArrayPBGAPlastic Ball Grid ArrayMAP-BGAMold Array Process Ball Grid ArrayμBGAMicro Ball Grid ArrayLFBGALow-profile Fine-pitch Ball Grid ArrayTBGAThin Ball Grid ArraySBGASuper Ball Grid ArrayUFBGAUltra-fine Ball Grid Array2. BQFP (Bumpered Quad Flat Pack)A four-sided pin flat package with bumpers, one of the QFP packages. A bulge (bumper) is arranged at the four corners of the package body to prevent pin bending during shipping and handling.3. CERDIP (Ceramic Dual In-line Package)Glass-sealed ceramic DIP used for ECL RAM, DSP (Digital Signal Processor), and other circuits. It is also used for UVEPROM or microcontrollers with EPROM.4. CERQUAD (Ceramic Quad Flat Package)One of the surface-mount packages, used for EPROM circuits. The heat-dissipation property is better than that of plastic QFP, allowing 1.5-2W power dissipation under natural air cooling conditions, but the packaging cost is 3-5 times higher than plastic QFP. Pin spacing includes 1.27mm, 0.8mm, 0.65mm, 0.5mm, and 0.4mm, with pin counts from 32 to 368.5. COB (Chip on Board)Chip on board packaging is one of the bare chip mounting technologies. A semiconductor chip is attached directly to the printed circuit board, and electrical connections between the chip and substrate are realized by wire bonding, then covered with resin to ensure reliability. The bare silicon chip, usually an integrated circuit, is supplied without a traditional package.6. DFP (Dual Flat Package)A flat package with pins on two sides.7. DIC (Dual In-line Ceramic Package)Nickname for ceramic DIP (including glass seals).8. DIP (Dual In-line Package)In microelectronics, a dual in-line package (DIP or DIL) is an electronic component package with a rectangular housing and two parallel rows of electrical connecting pins. The package may be through-hole mounted to a printed circuit board (PCB) or inserted in a socket. The packaging materials include plastic and ceramic. DIP is one of the most popular packages, used for standard logic ICs, memory LSI, and microcontroller circuits. Pin spacing is 2.54mm, pin count ranges from 6 to 64, and the packaging width is usually 15.2mm. Some packages with widths of 7.52mm and 10.16mm are called skinny DIP and slim DIP respectively. Ceramic DIP sealed with low melting point glass is also known as CERDIP.The following are the acronyms of the DIP family (they belong to through-hole packages):AcronymFull NameDIPDual In-line PackageCDIPCeramic DIPCERDIPGlass-sealed Ceramic DIPSDIPSkinny DIPSHDIPShrink DIPMDIPMolded DIPPDIPPlastic DIP9. DTCP (Dual Tape Carrier Package)The name for DTCP from the Electronic Industries Association of Japan.10. DIL (Dual In-line)Nickname for DIP. European semiconductor manufacturers often use this name.11. DSO (Dual Small Outline)Dual small-outline package, nickname for SOP. Some semiconductor manufacturers use this name.12. DTCP (Dual Tape Carrier Package)Dual TCP, with pins made on insulating tape and drawn from both sides of the package. Due to the use of TAB (Tape Automated Bonding) technology, the package is very thin. Often used in liquid crystal display driver LSI, but mostly as customized products.13. FP (Flat Package)One of the surface-mount packages. Nickname for QFP or SOP.14. Flip-chipOne of the bare chip packaging techniques. Metal bumps are fabricated in the electrode areas of the LSI chip, and then the chip is flipped and the metal bumps are connected to the electrode areas on the printed substrate. The occupied area of the package is basically the same as the chip size. It is the smallest and thinnest of all packaging types.15. FQFP (Fine Pitch Quad Flat Package)Small pin spacing QFP. Usually refers to a QFP with pin spacing less than 0.65mm. This name is used by some semiconductor manufacturers.16. GTPAC (Globe Top Pad Array Carrier)Nickname for BGA from Motorola Corporation (now part of NXP and ON Semiconductor).17. GQFP (Quad Flat Package with Guard Ring)QFP with protective ring. It is a plastic QFP with pins protected by a resin guard ring to prevent bending deformation.18. Pin Grid Arrays (PGA)A surface-mount or through-hole package with pins arranged in a grid pattern. Generally, through-hole PGA is a plug-in package with pin lengths of about 3.4mm. Surface-mount PGA has shorter pins on the bottom of the package, with lengths ranging from 1.5mm to 2.0mm.The following are series of the PGA family:AcronymFull NamePGA (Also known as PPGA)Pin Grid ArrayCPGACeramic Pin Grid ArrayFCPGAFlip-chip Pin Grid ArrayOPGAOrganic Pin Grid Array19. LCC (Leadless Chip Carrier)A surface-mount package with only electrode contacts but no pins on all four sides. It is used for high-speed and high-frequency IC packaging, also known as ceramic QFN or QFN-C.The following are series of the LCC family (a chip carrier is a rectangular package with contacts on all four edges):AcronymFull NameLCCLeadless Chip CarrierLCCLeaded Chip CarrierLCCCLeaded Ceramic Chip CarrierCLCCCeramic Leadless Chip CarrierDLCCDual Leadless Chip Carrier (ceramic)PLCCPlastic Leaded Chip Carrier20. JLCC (J-leaded Chip Carrier)Nickname for CLCC with window and ceramic QFJ with window. The name adopted by some semiconductor manufacturers.21. PLCC (Plastic Leaded Chip Carrier)One of the surface-mount packages, with pins drawn from the four sides of the package. Texas Instruments first used it for 64k-bit DRAM and 256k-bit DRAM, and it was widely used in logic LSI and memory devices in the 1990s.22. P-LCC (Plastic Leadless Chip Carrier)Sometimes it's a nickname for plastic QFJ, sometimes for QFN (plastic LCC). Some LSI manufacturers use PLCC to express leaded packaging and P-LCC for leadless packaging.23. PCLP (Printed Circuit Board Leadless Package)Printed circuit board packaging without leads. The name used by Fujitsu for plastic QFN (plastic LCC). Pin spacing: 0.55mm and 0.4mm.24. LGA (Land Grid Array)A package with array electrode contacts on the bottom. When assembling, it can be inserted into a socket or soldered directly to a PCB.25. LOC (Lead on Chip)One of the LSI packaging types, a structure in which the front end of the lead frame is located above the chip. Bump contacts are made near the center of the chip, which are electrically connected with wire bonding. The chip width contained in the same size package is reduced by approximately 1mm.26. LQFP (Low Profile Quad Flat Package)A type of QFP with a 1.4mm (or less) package body thickness. LQFP is the name used by the Electronic Industries Association of Japan according to the QFP shape specification.27. L-QUADOne of the ceramic QFP types. The thermal conductivity of aluminum nitride used for the package substrate is 7-8 times higher than that of alumina, providing excellent heat dissipation. The package frame is aluminum oxide and the chip is sealed by potting method, which reduces cost. It is a package developed for logic LSI.28. MCM (Multi-Chip Module)A package in which multiple semiconductor bare chips are mounted on a wiring substrate. According to substrate material, it can be divided into three categories: MCM-L, MCM-C, and MCM-D. MCM-L uses common glass epoxy multilayer printed substrate with lower wiring density and cost. MCM-C uses thick film technology to form multilayer wiring on ceramic (alumina or glass ceramic) substrates, similar to thick film hybrid ICs. MCM-C has higher wiring density than MCM-L. MCM-D uses thin-film techniques to create multilayer wiring on ceramic (alumina or aluminum nitride) substrates.29. MFP (Mini Flat Package)Nickname for plastic SOP or SSOP. The name adopted by some semiconductor manufacturers.30. MQFP (Metric Quad Flat Package)A classification of QFP according to JEDEC standards. It is a standardized QFP with pin spacing of 0.65mm and body thickness of 2.0mm to 3.8mm.31. MQUAD (Metal Quad)A QFP package developed by Olin Corporation. The substrate and seal cover are made of aluminum. It can dissipate 2.5W to 2.8W under natural air cooling conditions.32. MSP (Mini Square Package)Nickname for QFI, known as MSP in the early stages of development. QFI is the name specified by the Electronic Industries Association of Japan.33. OPMAC (Over Molded Pad Array Carrier)Molded resin sealed pad array carrier. The name for molded resin sealed BGA from Motorola Corporation.34. PAC (Pad Array Carrier)Nickname for BGA.35. PFPF (Plastic Flat Package)Nickname for Plastic QFP. The name used by some LSI manufacturers.36. PGA (Pin Grid Array)One of the plug-in packages in which vertical pins on the bottom are arranged in a grid pattern. The package substrate is basically multilayer ceramic. Most PGA packages are ceramic. They are used in high-speed and large-scale logic LSI circuits, with relatively high cost.37. Piggy BackA ceramic package with a socket, similar to DIP, QFP, and QFN. Used during equipment development with microcontrollers for program validation and debugging. For example, EPROM can be inserted into a socket for debugging.38. QFH (Quad Flat High Package)A type of plastic QFP. To prevent package body cracking, the QFP body is made thicker. The name adopted by some semiconductor manufacturers.39. QFI (Quad Flat I-leaded Package)One of the surface-mount packages. Pins are drawn from the four sides of the package. Attachment to printed substrate uses butt welding connection. Because the pins have no protruding parts, the mounting area is less than QFP.40. QFJ (Quad Flat J-leaded Package)One of the surface mount packages. Pins are drawn from the four sides of the package, bent down in J-shape. It is the name prescribed by the Electronic Industries Association of Japan. Pin spacing is 1.27mm.Available in plastic and ceramic materials. Plastic QFJ is called PLCC in most cases, used for microcontrollers, gate arrays, DRAM, ASSP, OTP circuits, etc., with pin counts from 18 to 84.Ceramic QFJ, also known as CLCC or JLCC. Packages with windows are used for UVEPROM and microcontroller chips with EPROM, with pin counts from 32 to 84.41. QFN (Quad Flat Non-leaded Package)One of the surface-mount packages. Also called LCC in the past. QFN is the name prescribed by the Electronic Industries Association of Japan. The four sides of the package have electrode contacts. Because there are no pins, the mounting area is smaller than QFP. Available in ceramic and plastic materials.42. QFP (Quad Flat Package)One of the surface-mount packages, with pins in L-shape extending from four sides. There are three substrate materials: ceramic, metal, and plastic. In terms of quantity, plastic packaging accounts for the majority. The disadvantage of QFP is that when pin spacing is less than 0.65mm, pins are prone to bending.43. QIC (Quad In-line Ceramic Package)Nickname for ceramic QFP. The name adopted by some semiconductor manufacturers.44. QIP (Quad In-line Plastic Package)Nickname for plastic QFP. The name adopted by some semiconductor manufacturers.45. QTCP (Quad Tape Carrier Package)One of the TCP packages with pins on insulating tape drawn from the four sides of the package. It is a thin package using TAB technology.46. QTP (Quad Tape Package)The name used by the Electronic Industries Association of Japan in April 1993 for the shape specification of QTCP.47. QUIL (Quad In-line)Nickname for QUIP.48. QUIP (Quad In-line Package)Pins are drawn from both sides of the package and bent down into four rows at alternate intervals. Pin spacing is 1.27mm, and when inserted into the printed substrate, the insertion center distance becomes 2.54mm. Therefore, it can be used on standardized printed circuit boards. It is a smaller package than standard DIP.49. SDIP (Shrink Dual In-line Package)One of the plug-in packages with the same shape as DIP, but with smaller pin spacing (1.778mm) compared to DIP (2.54mm). Pin counts range from 14 to 90, and substrate materials include both ceramic and plastic.50. SH-DIP (Shrink Dual In-line Package)Same as SDIP. The name adopted by some semiconductor manufacturers.51. SIL (Single In-line)Nickname for SIP. European semiconductor manufacturers adopt this name.52. SIMM (Single In-line Memory Module)A memory assembly with electrodes attached only to one side of the printed substrate. Usually refers to a plug-in component. Standard SIMM has 30 electrodes with 2.54mm pin spacing and 72 electrodes with 1.27mm pin spacing. Note: SIMM has been largely replaced by DIMM (Dual In-line Memory Module) in modern systems.53. SIP (Single In-line Package)Pins are drawn from one side of the package and arranged in a straight line. When assembled on the printed substrate, the package is in a lateral position. Pin spacing is usually 2.54mm, pin count ranges from 2 to 23, and related products are mostly customized.54. SK-DIP (Skinny Dual In-line Package)A type of skinny DIP with body width of 7.62mm and pin spacing of 2.54mm. Usually referred to simply as DIP.55. SMD (Surface Mount Devices)Some semiconductor manufacturers classify SOP as SMD at times.56. SOI (Small Outline I-leaded Package)One of the surface mount packages with I-shaped pins. Pins extend down from both sides of the package in I-shape with 1.27mm pin spacing. Surface mount area is less than SOP.57. SOIC (Small Outline Integrated Circuit)Nickname for SOP. Many semiconductor manufacturers abroad adopt this name.58. SOJ (Small Outline J-Leaded Package)One of the surface-mount packages with J-shaped pins. Pins extend down from both sides of the package in J-shape. Usually plastic. Mostly used for memory LSI circuits such as DRAM and SRAM, but predominantly DRAM.59. SOL (Small Outline L-leaded Package)The name used for SOP in accordance with JEDEC (Joint Electron Device Engineering Council) memory standards.60. SONF (Small Outline Non-Fin)Same as regular SOP but without heat sink fins. To distinguish power IC packages without heat sinks, the NF (non-fin) designation is intentionally added. The name adopted by some semiconductor manufacturers.61. SOP (Small Outline Package)One of the surface-mount packages in which pins are drawn from both sides of the package in L-shape. Substrate materials include plastic and ceramic. Also called SOL and DFP.Used for memory LSI and widely used for small-scale circuits such as ASSP.62. SOW (Small Outline Package - Wide Type)A wide-type SOP. The name adopted by some semiconductor manufacturers.III Development of Integrated CircuitsThe most advanced integrated circuits are the cores of microprocessors or multi-core processors that control everything from computers to mobile phones and even smart home appliances. Although the cost of designing and developing complex integrated circuits is very high, mass production generates huge profits. The performance of integrated circuits is very high because small size brings short signal paths, enabling low-power logic circuits with fast switching speeds.With technological development, integrated circuits have continued to shrink, allowing each chip to contain more circuits. This increases capacity per unit area, reducing costs and increasing functionality. Generally, as feature size decreases, almost all indicators improve: unit cost and switching power consumption decrease while speed increases. However, ICs also face challenges. For example, ICs with nanometer-scale devices experience leakage current, which increases power consumption and decreases operational efficiency. The IC industry continues to innovate to address these challenges.In just over half a century since its development, integrated circuits have become ubiquitous and indispensable. They are essential components of modern life, found in computers, mobile phones, and other digital appliances. Modern computing, communication, manufacturing, transportation systems, and artificial intelligence all depend on integrated circuits. Many scholars believe that the digital revolution brought about by integrated circuits is one of the most important events in human history. The tremendous development of ICs represents progress not only in design and semiconductor technology but also in higher-level technical fields including AI, quantum computing, and advanced materials science.IV Types of Integrated CircuitsThere are many ways to classify integrated circuits.4.1 By Signal TypeIntegrated circuits can be divided into: analog integrated circuits, digital integrated circuits, and mixed-signal integrated circuits.- Digital Integrated CircuitsDigital integrated circuits can contain logic gates, flip-flops, multiplexers, and other circuits ranging from thousands to billions of transistors in a few square millimeters. Despite their small size, they enable higher speed, lower power consumption, and lower manufacturing costs than board-level integration. These digital ICs, represented by microprocessors, digital signal processors, and microcontrollers, process binary "1" and "0" signals.- Analog Integrated CircuitsAnalog integrated circuits include sensors, power control circuits, operational amplifiers, and other components that process analog signals. They can perform amplification, filtering, demodulation, mixing, and other functions. Using analog integrated circuits lightens the burden on circuit designers, eliminating the need to design everything from individual transistors.- Mixed-Signal Integrated CircuitsMixed-signal integrated circuits integrate both analog and digital circuits on a single chip to create devices such as analog-to-digital converters (ADCs) or digital-to-analog converters (DACs). They offer smaller size and lower cost but require careful attention to signal interference issues.4.2 By ApplicationIntegrated circuits can be divided into standard general-purpose integrated circuits and application-specific integrated circuits (ASICs) according to their application fields.4.3 By Package FormIntegrated circuits can be divided into circular (metal transistor package, generally suitable for high power), flat (good stability, small size), and dual in-line types according to package shape.Practical application categories include:1. Television integrated circuits: Include line and field scanning ICs, intermediate amplifier ICs, audio ICs, color decoding ICs, AV/TV conversion ICs, switching power supply ICs, remote control ICs, digital signal processing ICs, picture-in-picture processing ICs, CPU, memory ICs, and display driver ICs.2. Audio integrated circuits: Include AM/FM high-frequency circuits, stereo decoding circuits, audio preamplifier circuits, audio operational amplifier ICs, audio power amplifier ICs, surround sound processing ICs, level driver ICs, electronic volume control ICs, delay/reverb ICs, and electronic switch ICs.3. Video player integrated circuits: Include system control ICs, video encoding ICs, MPEG decoding ICs, audio signal processing ICs, sound effect ICs, RF signal processing ICs, digital signal processing ICs, servo ICs, and motor driver ICs.4. Computer integrated circuits: Include CPUs, RAM, ROM, cache memory, GPU, I/O control circuits, and chipsets.5. Communication integrated circuits: Include RF transceivers, baseband processors, power amplifiers, and network processors.6. Automotive integrated circuits: Include engine control units (ECUs), sensor interfaces, power management ICs, and advanced driver-assistance systems (ADAS) processors.7. IoT and sensor integrated circuits: Include low-power microcontrollers, wireless connectivity ICs (Wi-Fi, Bluetooth, LoRa), and sensor interface ICs.V Best Practices for IC Testing and Handling1. Understand the IC's working principle before testingBefore inspecting and repairing integrated circuits, familiarize yourself with the IC's function, internal circuit architecture, main electrical parameters, pin functions, normal voltage levels, frequency waveforms, and peripheral components.2. Avoid short circuits between pins during testingWhen measuring voltage or waveforms with an oscilloscope probe, avoid short circuits between pins. It's best to measure at peripheral printed circuit traces directly connected to pins. Any momentary short circuit can easily damage IC devices, especially when testing CMOS ICs which require extra care.3. Use proper isolation when testingWhen working with equipment, especially high-power devices, ensure proper electrical isolation. Always verify whether the chassis is grounded to prevent power supply short circuits and equipment damage.4. Ensure proper soldering iron insulationNever solder while power is on. The soldering iron shell should be grounded. For MOS circuits, use a low-voltage soldering iron (6V to 8V) or ESD-safe equipment for added safety.5. Ensure high-quality solderingDuring soldering, avoid solder bridges and cold joints. Soldering time should not exceed 3 seconds, and soldering iron power should be around 25W. After soldering ICs, carefully inspect for shorts between pins using an ohmmeter before applying power.6. Don't hastily conclude IC damageDon't immediately assume an IC is damaged. Since most ICs use direct coupling, abnormal operation in one circuit can cause voltage changes in multiple locations, which doesn't necessarily indicate IC damage. Additionally, in some cases, pin voltages may appear normal or close to normal values, but this doesn't guarantee the IC is functioning properly, as some faults don't affect DC voltage levels.7. Use high-impedance test instrumentsWhen measuring DC voltage at IC pins, use a multimeter with input impedance greater than 20kΩ/V to avoid significant measurement errors on some pins.8. Ensure adequate heat dissipation for power ICsPower integrated circuits must have proper heat dissipation and should not operate at high power without heat sinks.9. Design reasonable circuit layoutsIf adding peripheral components to replace damaged internal IC functions, use small components and design reasonable wiring to avoid unnecessary parasitic coupling. Pay special attention to grounding between audio power amplifier ICs and preamplifier circuits.10. Follow ESD protection proceduresAlways use ESD-safe handling procedures, including wrist straps, ESD mats, and proper grounding when working with sensitive ICs, especially CMOS and high-frequency devices.Frequently Asked Questions (FAQs)1. What is an IC used for?An integrated circuit (IC) is a small chip that can function as an amplifier, oscillator, timer, microprocessor, memory, or even a complete computer system. An IC is a small wafer, usually made of silicon, that can contain anywhere from hundreds to billions of transistors, resistors, and capacitors. ICs are used in virtually all electronic equipment today, including smartphones, computers, automobiles, medical devices, industrial equipment, and IoT devices.2. How does an IC work?Integrated circuits are combinations of diodes, microprocessors, and transistors in miniaturized form on a silicon wafer. Transistors are used to store voltages, stabilize circuits, amplify signals, and function as switches in digital circuits. The interconnected components work together to perform specific functions, from simple logic operations to complex computational tasks.3. What is an IC diagram?In an electronic schematic diagram, an integrated circuit is usually represented as a rectangle with circuit connections placed conveniently around it without regard for the physical positioning of the pins. The schematic diagram shows the logical connections and functions rather than the physical layout. Detailed IC diagrams include pin numbers, power connections, and functional blocks.4. How are IC pins numbered?IC pins are numbered sequentially (pin 1, pin 2, pin 3, etc.). On a DIP IC, a half-circle notch or dot indicates pin 1's location. With the notch or dot oriented at the top, pin 1 of a DIP IC is always the top-left pin, and numbering continues counter-clockwise. For surface-mount packages like QFP, pin 1 is typically marked with a dot, and numbering proceeds counter-clockwise from that corner.5. What are the different types of IC packages?Common IC package types include:DIP (Dual In-line Package) - through-hole mountingSOP/SOIC (Small Outline Package) - surface mountQFP (Quad Flat Package) - surface mount with pins on four sidesQFN (Quad Flat No-lead Package) - surface mount, leadlessBGA (Ball Grid Array) - surface mount with solder ballsCSP (Chip Scale Package) - very small surface mountPGA (Pin Grid Array) - through-hole with pins in grid patternLGA (Land Grid Array) - surface mount with contact pads6. How do you use an IC in a circuit?To use an IC in a circuit: 1) Identify the IC's pin configuration from its datasheet, 2) Connect power supply pins (VCC/VDD and GND) with appropriate bypass capacitors, 3) Connect input and output pins according to your circuit requirements, 4) Add any required external components (resistors, capacitors, crystals) as specified in the datasheet, 5) Ensure proper signal levels and timing, and 6) Follow ESD precautions during handling and installation.7. How are ICs named?IC naming conventions vary by manufacturer but typically include: a prefix indicating the manufacturer or series (e.g., "SN" for Texas Instruments), a number indicating the device family or function (e.g., "74" for 7400 series logic), additional digits specifying the exact function, and sometimes suffixes indicating package type, temperature range, or speed grade. For example, "SN74HC00N" indicates a Texas Instruments 7400 series high-speed CMOS quad NAND gate in a DIP package.8. Which ICs are most commonly used?Some of the most commonly used ICs include: the 555 timer (invented in 1971, still widely used), operational amplifiers like the LM358 and TL072, voltage regulators such as the 7805 series, microcontrollers like Arduino-compatible ATmega chips and ARM Cortex processors, memory chips (DRAM, Flash), and logic gates from the 74 series. Modern applications heavily use system-on-chip (SoC) designs that integrate multiple functions.9. How many types of ICs are there?There are thousands of different IC types. Standard logic ICs alone include roughly 600 types, from basic chips to highly functional arithmetic-logic units. ICs are implemented using different technologies: TTL (Transistor-Transistor Logic) and CMOS being the most common. By function, ICs can be categorized as analog, digital, or mixed-signal. By application, they include microprocessors, memory, power management, communication, sensors, and many specialized functions.10. What are the advantages of ICs?Advantages of ICs include: extremely small physical size compared to discrete circuits, very light weight, high reliability due to fewer interconnections, lower power consumption, faster operation due to shorter signal paths, lower cost in mass production, better performance consistency, improved noise immunity, easier circuit design and assembly, and reduced maintenance requirements. However, ICs are difficult to repair if damaged and typically must be replaced as complete units.11. What is Moore's Law and is it still relevant?Moore's Law, proposed by Gordon Moore in 1965, observed that the number of transistors on integrated circuits doubles approximately every two years. As of 2025, while the pace has slowed somewhat, the semiconductor industry continues to advance through innovations in 3D chip stacking, new materials like gallium nitride (GaN), and advanced packaging techniques. The focus has shifted from pure transistor density to improving performance per watt, specialized AI accelerators, and chiplet architectures.12. What is the difference between an IC and a microprocessor?An IC (Integrated Circuit) is a general term for any chip containing electronic components. A microprocessor is a specific type of IC that contains a central processing unit (CPU) capable of executing instructions and performing computations. All microprocessors are ICs, but not all ICs are microprocessors. Other IC types include memory chips, analog circuits, power management ICs, and sensors.13. How are ICs manufactured?IC manufacturing involves multiple complex steps: 1) Silicon wafer preparation from purified silicon, 2) Photolithography to pattern circuit designs using UV light and photoresist, 3) Etching to remove unwanted material, 4) Doping to create P-type and N-type semiconductor regions, 5) Deposition of insulating and conducting layers, 6) Multiple repetitions of these steps to build up circuit layers, 7) Testing of individual dies on the wafer, 8) Dicing the wafer into individual chips, and 9) Packaging and final testing. Modern fabs can cost billions of dollars and require extremely clean environments.14. What is the difference between ASIC and FPGA?ASIC (Application-Specific Integrated Circuit) is a custom-designed IC optimized for a specific application, offering high performance and efficiency but requiring significant upfront design costs. FPGA (Field-Programmable Gate Array) is a reconfigurable IC that can be programmed after manufacturing, offering flexibility and faster time-to-market but typically with lower performance and higher power consumption than ASICs. FPGAs are ideal for prototyping, low-volume production, or applications requiring updates, while ASICs are preferred for high-volume, performance-critical applications.15. What are emerging IC technologies in 2025?Emerging IC technologies as of 2025 include: 1) 3nm and smaller process nodes using extreme ultraviolet (EUV) lithography, 2) 3D chip stacking and chiplet architectures for improved performance and yield, 3) Neuromorphic computing chips mimicking brain function, 4) Quantum computing processors, 5) Photonic integrated circuits using light instead of electricity, 6) Advanced packaging techniques like fan-out wafer-level packaging, 7) AI-specific accelerators and neural processing units (NPUs), 8) Wide-bandgap semiconductors (GaN, SiC) for power electronics, and 9) Flexible and stretchable electronics for wearable devices.VI IC Applications Across Industries6.1 Consumer ElectronicsICs are fundamental to modern consumer electronics. Smartphones contain dozens of specialized ICs including application processors, memory chips, power management ICs, RF transceivers, camera image processors, and display drivers. Smart TVs use ICs for video processing, audio enhancement, connectivity (Wi-Fi, Bluetooth), and smart features. Wearable devices like smartwatches and fitness trackers rely on low-power microcontrollers, sensor interface ICs, and wireless communication chips.6.2 Automotive IndustryModern vehicles contain hundreds of ICs controlling everything from engine management to infotainment systems. Advanced Driver Assistance Systems (ADAS) use specialized processors for real-time image processing, radar signal processing, and sensor fusion. Electric vehicles require power management ICs for battery management, motor control, and charging systems. Automotive ICs must meet stringent reliability and temperature requirements (AEC-Q100 qualification).6.3 Industrial and IoT ApplicationsIndustrial automation relies on ICs for motor control, sensor interfaces, industrial communication protocols (CAN, Modbus, EtherCAT), and programmable logic controllers (PLCs). IoT devices use ultra-low-power microcontrollers, wireless connectivity ICs (LoRa, NB-IoT, Zigbee), and energy harvesting circuits to enable battery-powered operation for years. Smart home devices integrate multiple functions into system-on-chip designs.6.4 Medical DevicesMedical electronics use specialized ICs for patient monitoring, diagnostic imaging, implantable devices, and therapeutic equipment. These ICs must meet strict regulatory requirements (FDA, CE marking) and often require ultra-low power consumption, high precision, and biocompatibility. Examples include pacemaker controllers, blood glucose monitor ICs, and ultrasound signal processors.6.5 Telecommunications and Data Centers5G infrastructure relies on high-frequency RF ICs, digital signal processors, and network processors. Data centers use specialized ICs for server processors, network switches, storage controllers, and AI acceleration. Power efficiency is critical, driving development of specialized chips optimized for specific workloads like machine learning inference or video transcoding.VII Future Trends in IC Technology7.1 Advanced Manufacturing ProcessesThe semiconductor industry continues pushing toward smaller process nodes. As of 2025, leading manufacturers are producing 3nm chips with plans for 2nm and beyond. These advances use extreme ultraviolet (EUV) lithography, gate-all-around (GAA) transistor structures, and new materials. However, physical and economic limits are driving innovation in alternative approaches like 3D stacking and chiplet architectures.7.2 Heterogeneous IntegrationRather than making single monolithic chips larger and more complex, the industry is moving toward chiplet designs where multiple smaller chips (dies) are integrated in a single package. This approach improves yield, allows mixing different process technologies, and enables modular designs. Advanced packaging techniques like TSMC's CoWoS (Chip-on-Wafer-on-Substrate) and Intel's EMIB (Embedded Multi-die Interconnect Bridge) enable high-bandwidth connections between chiplets.7.3 AI and Machine Learning AccelerationSpecialized AI accelerators and neural processing units (NPUs) are becoming standard in devices from smartphones to data center servers. These chips use architectures optimized for matrix multiplication and other AI operations, offering orders of magnitude better performance and energy efficiency than general-purpose processors for AI workloads. Edge AI chips enable on-device processing for privacy and latency-sensitive applications.7.4 Quantum ComputingWhile still in early stages, quantum computing ICs are advancing rapidly. These chips operate at near absolute zero temperatures and manipulate quantum bits (qubits) to perform certain calculations exponentially faster than classical computers. Companies like IBM, Google, and Intel are developing increasingly capable quantum processors, though practical large-scale quantum computers remain years away.7.5 Sustainable and Green ElectronicsEnvironmental concerns are driving development of more energy-efficient ICs and sustainable manufacturing processes. This includes ultra-low-power designs for battery-powered devices, power management ICs for renewable energy systems, and efforts to reduce water and chemical usage in semiconductor manufacturing. The industry is also addressing electronic waste through improved recyclability and longer product lifespans.VIII ConclusionIntegrated circuits have transformed from simple devices containing a few transistors to incredibly complex systems with billions of components. They are the foundation of modern technology, enabling everything from smartphones and computers to artificial intelligence and autonomous vehicles. As we move forward, ICs will continue to evolve through advanced manufacturing processes, new materials, innovative architectures, and specialized designs for emerging applications.Understanding IC fundamentals, packaging types, and applications is essential for anyone working in electronics, whether as a hobbyist, student, or professional engineer. The field continues to offer exciting opportunities for innovation and remains one of the most important technologies shaping our future.Article Update Information:This article was originally published in 2016 and has been comprehensively updated in November 2025 to reflect current IC technologies, manufacturing processes, and applications. Updates include:Current transistor densities and process node information (3nm and beyond)Modern packaging technologies and advanced integration techniquesEmerging applications in AI, automotive, IoT, and 5GUpdated best practices for IC handling and testingExpanded FAQ section with 15 comprehensive questions and answersNew sections on industry applications and future trendsCorrected outdated references (e.g., tape recorders replaced with modern devices)Improved HTML structure with proper heading hierarchyEnhanced technical accuracy and clarity throughoutLast updated: November 2025

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