With the rapid development of the modern electronics industry, the integration of power devices of electronic products is getting higher and higher, and the problem of heat generation is becoming more and more serious, and it has seriously affected the service life and reliability of products.
When the MOSFET heat sink is working, the heat generation is very large. If the MOSFET heat dissipation effect is not good, the temperature may be too high, which may cause the MOSFET to be burned, which may lead to the damage of the entire circuit board. The traditional high-power inverter MOSFET is arranged on the circuit board, and the radiator is also arranged on the circuit board. The MOSFET is in contact with the radiator. When the circuit is working, the heat dissipated by the MOSFET is quickly dissipated by the radiator.
If the circuit power is high, the number of MOSFET will be relatively large. According to the current MOSFET heat dissipation structure, the length of the radiator and the circuit board can only be increased to provide heat dissipation for all MOSFET, which will increase the volume of the chassis. The heat dissipation structure has poor heat dissipation effect. Some high-power inverter MOSFET will install ventilation paper to dissipate heat, but it is very troublesome to install ventilation paper. Therefore, MOSFETs have high requirements for heat dissipation, and the heat dissipation conditions are divided into the lowest and the highest, that is, the upper and lower floating range of the heat dissipation during operation. Generally, the worst heat dissipation conditions are used as the standard when purchasing, so that the maximum safety margin can be left during use, and the normal operation of the system can be ensured even in high temperatures.
At present, screws are used to fasten the MOSFET and the heat sink. The MOSFET is a device that generates a relatively large amount of heat, so it is generally equipped with a heat sink when it is used, usually a small aluminum heat sink. In order to improve the heat dissipation performance, the heat of the MOSFET must be introduced into the radiator as much as possible, and the thermal resistance between the MOSFET and the radiator needs to be reduced, so what thermal insulation material is better to choose?
I have also seen the use of soft thermal pads when disassembling some electronic products. CoolThermo feels that the soft thermal pad is still not very safe, because the strength is not enough, it is easy to damage the adhesive layer when the screw is installed, and the breakdown occurs. Therefore, thermally conductive insulating sheets are generally used. The strength of the thermal insulation sheet should also be considered, and it must withstand a certain amount of tightening force without being damaged.
It is worth mentioning that MOSFET usually adopts the design of heat sink and thermal conductive silicone to directly contact heat dissipation. If the MOSFET shell cannot be grounded, it can be isolated by insulating gasket and then used thermal conductive silicone grease to dissipate heat. Silicone sheets can also be used to cover the MOSFET, which can prevent static electricity damage in addition to heat dissipation.
Installing thermally conductive insulating material between the MOSFET and the heat sink can greatly reduce the interface thermal resistance, increase the heat dissipation efficiency, ensure that the MOSFET operating temperature is maintained within a reasonable range, and enable the system to operate stably and reliably.