How PCB design can improve heat dissipation?

How PCB design can improve heat dissipation?

1. Add heat-dissipating copper foil and copper foil with large area power supply;

a. The larger the area connected to the copper skin, the lower the junction temperature

b. The larger the copper area, the lower the junction temperature.

2. Thermal vias;

Thermal vias can effectively reduce the junction temperature of the device, improve the uniformity of the temperature in the thickness direction of the board, and provide the possibility of adopting other heat dissipation methods on the back of the PCB. Through simulation, it is found that compared with non-thermal vias, the thermal power consumption of the device is 2.5W, the spacing is 1mm, and the 6x6 thermal vias in the center 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 the thermal via array is changed to 4x4, the junction temperature of the device has increased by 2.2°C compared with 6x6, which is worthy of attention.

3. The copper is exposed on the back of the IC to reduce the thermal resistance between the copper skin and the air;

4. PCB layout: requirements for high-power and thermal-sensitive devices;

a. Place the heat sensitive device in the cold wind area.

b. Place the temperature detection device in the hottest position.

c. The devices on the same printed board should be arranged as far as possible according to their calorific value and degree of heat dissipation. Devices with low calorific value or poor heat resistance (such as small signal transistors, small-scale integrated circuits, electrolytic capacitors, etc.) should be placed The uppermost flow of the cooling airflow (at the entrance), and the devices with large heat generation or good heat resistance (such as power transistors, large-scale integrated circuits, etc.) are placed at the lowermost of the cooling airflow.

d. In the horizontal direction, high-power devices are arranged as close as possible to the edge of the printed board to shorten the heat transfer path; in the vertical direction, high-power devices are arranged as close as possible to the top of the printed board to reduce the temperature of other devices when these devices work. Impact.

e. The heat dissipation of the printed board in the equipment mainly relies on air flow, so the air flow path should be studied during the design, and the device or printed circuit board should be reasonably configured. When air flows, it always tends to flow in places with low resistance, so when configuring devices on a printed circuit board, avoid leaving a large airspace in a certain area. The configuration of multiple printed circuit boards in the whole machine should also pay attention to the same problem.

f. 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 heating device. It is best to stagger multiple devices on the horizontal plane.

g. Arrange the devices with the highest power consumption and the highest heat generation near the best position for heat dissipation. Do not place high-heating devices on the corners and peripheral edges of the printed board, unless a heat sink is arranged near it. When designing the power resistor, choose a larger device as much as possible, and make it have enough space for heat dissipation when adjusting the layout of the printed board.