1. High heating device with heat sink and heat conduction plate

When there are a few components in the PCB that have a high heat output (less than 3), a heat sink or heat transfer tube can be added to the heating device. When the temperature cannot be lowered, a heat sink with a fan can be used to enhance the heat dissipation effect.When there are a large number of heating devices (more than 3), a large heat dissipation cover (board) can be used. It is a specialized heat sink customized according to the position and height of the heating devices on the PCB board, or different component high and low positions can be cut out on a large flat heat sink.Snap the heat dissipation cover onto the surface of each component as a whole and dissipate heat by contacting each component.However, due to poor consistency in height during component assembly and welding, the heat dissipation effect is not good.Generally, soft thermal phase change Thermally conductive pad is added on the surface of components to improve the heat dissipation effect.

2. Heat dissipation through the PCB board itself

Currently, the widely used PCB boards are copper clad/epoxy glass cloth substrates or phenolic resin glass cloth substrates, as well as a small amount of paper based copper clad boards.Although these substrates have excellent electrical and processing properties, their heat dissipation is poor. As a heat dissipation pathway for high heating components, it is almost impossible to rely on the resin of the PCB itself to transmit heat, but rather to dissipate heat from the surface of the component to the surrounding air.But as electronic products have entered the era of miniaturization, high-density installation, and high heat generation assembly, relying solely on the surface of very small components for heat dissipation is not enough.At the same time, due to the widespread use of surface mounted components such as QFP and BGA, a large amount of heat generated by the components is transferred to the PCB board. Therefore, the best way to solve heat dissipation is to improve the heat dissipation ability of the PCB itself, which is directly in contact with the heating element, and transmit or emit it through the PCB board.

3. Adopting a reasonable wiring design to achieve heat dissipation

Due to the poor thermal conductivity of the resin in the board, and the copper foil circuit and holes being good conductors of heat, Jieduobang PCB believes that improving the residual rate of copper foil and increasing thermal conductivity holes are the main means of heat dissipation.

To evaluate the heat dissipation capacity of a PCB, it is necessary to calculate the equivalent thermal conductivity (9 eq) of a composite material composed of various materials with different thermal conductivity - an insulating substrate for PCB.

For equipment that uses free convection air cooling, it is best to arrange integrated circuits (or other devices) in a longitudinal or transverse arrangement.

5. The devices on the same printed board shall be arranged in zones as far as possible according to their calorific value and heat dissipation degree. The devices with small calorific value or poor heat resistance (such as small signal transistors, small-scale integrated circuits, Electrolytic capacitor, etc.) shall be placed at the top (entrance) of the cooling air flow, and the devices with large calorific value or good heat resistance (such as power transistors, large-scale integrated circuits, etc.) shall be placed at the bottom of the cooling air flow.

6. In the horizontal direction, high-power devices should be 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 should be arranged as close as possible to the top of the printed circuit board to reduce the impact of these devices on the temperature of other devices during operation.

7. It is best to place temperature sensitive devices in the lowest temperature area (such as the bottom of the device), and never place them directly above the heating device. Multiple devices should be staggered on a horizontal plane.

8. The heat dissipation of the printed circuit board in the equipment mainly relies on air flow, so during design, it is necessary to study the air flow path and reasonably configure the components or printed circuit board.When air flows, it always tends to flow in areas with low resistance, so when configuring devices on printed circuit boards, it is important to avoid leaving large voids in certain areas.The configuration of multiple printed circuit boards in the entire machine should also pay attention to the same issues.

9. Avoid the concentration of hot spots on the PCB, distribute power evenly on the PCB board as much as possible, and maintain uniform and consistent surface temperature performance of the PCB.It is often difficult to achieve strict uniform distribution during the design process, but it is important to avoid areas with high power density to avoid overheating that may affect the normal operation of the entire circuit.If conditions permit, it is necessary to conduct thermal efficiency analysis of printed circuits. For example, the addition of thermal efficiency index analysis software modules in some professional PCB design software can help designers optimize circuit design.

10. Place the devices with the highest power consumption and maximum heat generation near the optimal heat dissipation location.Do not place devices with high heat generation at the corners and edges of the printed circuit board, unless there are heat dissipation devices arranged near them.When designing power resistors, try to choose larger devices as much as possible, and adjust the layout of the printed circuit board to have sufficient heat dissipation space.

11. High heat dissipation devices should minimize the thermal resistance between them when connected to the substrate.In order to better meet the thermal characteristics requirements, some thermal conductive materials (such as applying a layer of thermal conductive silicone) can be used on the bottom surface of the chip, and a certain contact area can be maintained for device heat dissipation.

12. Connection between device and substrate:

(1) Minimize the length of device leads as much as possible;

(3) Choose devices with a higher number of pins.

13. Packaging selection of devices:

(2) Consideration should be given to providing a good heat conduction path between the substrate and device packaging;

(3) Air separation should be avoided in the heat conduction path, and if this is the case, thermal conductive materials can be used for filling.