How to Improve Heat Dissipation with PCB Design
For electronic devices, a certain amount of heat is generated during operation, which causes the internal temperature of the device to rise rapidly.
If the heat is not dissipated in time, the device will continue to heat up, the device will fail due to overheating, and the reliability of the electronic device will decrease.
Therefore, it is very important to perform a good heat dissipation process on the board.
- 1. Add heat-dissipating copper foil and copper foil with large-area power supply.
As can be seen from the above figure, the larger the area connecting the copper, the lower the junction temperature.
According to the above figure, it can be seen that the larger the copper area, the lower the junction temperature.
- 2. Thermal Vias
Thermal vias can effectively reduce the junction temperature of the device and increase the uniformity of the temperature in the thickness direction of the board, which makes it possible to adopt other heat dissipation methods on the back side of the PCB.
Through simulation, it is found that compared with the non-thermal via, the thermal via of the device with a thermal power consumption of 2.5W, a pitch of 1mm, and a central design of 6x6 can reduce the junction temperature by about 4.8°C, and the temperature difference between the top and bottom of the PCB. Reduced from the original 21 ° C to 5 ° C. After changing the thermal via array to 4x4, the junction temperature of the device is 2.2°C higher than that of 6x6, which is worthy of attention.
- 3. Theexposed copper on the back of the IC reduces the thermal resistance between the copper and air.
- 4. PCB layout
High power, thermal device requirements.
a. The heat sensitive device is placed in the cold air area.
b. The temperature sensing device is placed in the hottest position.
c. The devices on the same printed board should be arranged as far as possible according to their heat generation and heat dissipation. Devices with low heat generation or poor heat resistance (such as small signal transistors, small scale integrated circuits, electrolytic capacitors, etc.) should be placed. The uppermost flow (at the inlet) of the cooling airflow, the device that generates a large amount of heat or heat (such as a power transistor, a large-scale integrated circuit, etc.) is placed at the most downstream of the cooling airflow.
d. In the horizontal direction, the high-power devices are placed as close as possible to the edge of the printed board to shorten the heat transfer path; in the vertical direction, the high-power devices are placed as close as possible to the top of the printed board, so as to reduce the temperature of other devices while the devices are operating. Impact.
e. The heat dissipation of the printed circuit board in the device mainly depends on the air flow, so the air flow path should be studied during the design, and the device or the printed circuit board should be properly configured. When the air flows, it tends to flow in a place with low resistance. Therefore, when configuring the device on the printed circuit board, avoid leaving a large air space in a certain area. The same problem should be noted in the configuration of multiple printed circuit boards in the whole machine.
f. Temperature sensitive devices should be placed in the lowest temperature area (such as the bottom of the device). Do not place it directly above the heating device. Multiple devices are preferably staggered on a horizontal plane.
g. Place the device with the highest power consumption and maximum heat generation near the best position for heat dissipation. Do not place a device with a higher heat on the corners and peripheral edges of the printed board unless a heat sink is placed near it. When designing the power resistor, choose a larger device as much as possible, and have enough space for heat dissipation when adjusting the layout of the printed board.
h. component spacing recommendations:
