Because there are a large number of high-power semiconductor devices with relatively large heat generation in the switching power supply. Such as rectifier bridge stack, high current rectifier, high power transistor or field effect tube and other devices. If the heat of these relatively large components can not be reasonably discharged, it will affect the normal operation of the switching power supply. To improve the stability of the switching power supply, when the thermal design of the switching power supply is designed, the heat dissipation becomes a A very important link in the design of switching power supplies. Several methods commonly used in the thermal design of switching power supplies are: the use of passive heat dissipation (radiators, cooling fans), metal PCBs, and thermally conductive graphite sheets. In actual applications, the above requirements should be tailored to customer requirements and the best and most reasonable solutions. Used in switching power supply. Let's take a look at the application of thermally conductive graphite sheet in switching power supply to solve the heat problem:

1. From the perspective of conducive to heat dissipation, the printed plate is preferably installed upright, and the distance between the board and the board should generally not be less than 20mm.

2. The devices on the same printed board should be arranged according to their heat generation and heat dissipation as much as possible. Devices with small heat generation or poor heat resistance (such as small signal transistors, small-scale integrated circuits, electrolytic capacitors, etc.) are placed in The uppermost part of the cooling airflow (at the entrance), the devices with large heat generation or good heat resistance (such as power transistors, large-scale integrated circuits, etc.) are placed at the most downstream of the cooling airflow.

3. In the horizontal direction, high-power devices should be placed as close to the edge of the printed board as possible to shorten the heat transfer path; in the vertical direction, the high-power devices should be placed as close as possible to the top of the printed board to reduce the temperature of these devices on other devices during operation Impact.

4. The temperature-sensitive device is best placed in the lowest temperature area (such as the bottom of the device). Never place it directly above the heat-generating device. Multiple devices are preferably staggered on the horizontal plane.

5. The heat dissipation of the printed board in the device mainly depends on the air flow, so the air flow path should be studied in the design, and the device or the printed circuit board should be reasonably configured. When the air flows, it tends to flow where the resistance is small, so when configuring devices on the printed circuit board, it is necessary to avoid leaving a large air space in a certain area. The configuration of multiple printed circuit boards in the whole machine should also pay attention to the same problem.