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PCB board cooling design tips

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Published by: Keyou September 30,2019

Overheating of the device will cause the device to fail, and the reliability of the electronic device will decrease. Therefore, the heat dissipation of the PCB circuit board is a very important link.

 

 For electronic equipment, a certain amount of heat is generated during operation, so that the internal temperature of the equipment rises rapidly. If the heat is not released in time, the equipment will continue to heat up, the device will fail due to overheating, and the electronic equipment is reliable. Performance will drop. Therefore, it is very important to perform a good heat dissipation process on the PCB board.

 

                    PCB board cooling design tips

 

1. Through the PCB circuit board itself, the currently widely used PCB board is a copper-clad/epoxy glass cloth substrate or a phenolic resin glass cloth substrate. Although these substrates have excellent electrical properties and processability, they have poor heat dissipation properties. However, as electronic products have entered the era of miniaturization, high-density mounting, and high-heat assembly, it is not enough to dissipate heat from the surface of a component with a very small surface area. At the same time, due to the large-scale use of surface mount components such as QFP and BGA, the heat generated by the components is transmitted to the PCB circuit board in a large amount. Therefore, the best way to solve the heat dissipation is to improve the heat dissipation capability of the PCB circuit board directly contacting the heat generating component. Conducted out or emitted through the PCB board.

 

2. For devices that use free convection air cooling, it is best to arrange the integrated circuits (or other devices) in a vertically long manner or in a horizontally long manner.

 

3, using a reasonable wiring design to achieve heat dissipation Because the resin in the sheet is poor thermal conductivity, and the copper foil line and hole is a good conductor of heat, so increasing the copper foil residual rate and increasing the heat conduction hole is the main means of heat dissipation. To evaluate the heat dissipation capability of a PCB board, it is necessary to calculate the equivalent thermal conductivity (nine eq) of a composite material composed of various materials having different thermal conductivity coefficients, and an insulating substrate for a PCB circuit board.

 

4. 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 these devices are operating. Impact.

 

5. The temperature-sensitive device should be placed in the lowest temperature area (such as the bottom of the device). Do not place it directly above the heat-generating device. Multiple devices are preferably staggered on a horizontal plane.

 

6. Avoid the concentration of hotspots on the PCB circuit board, distribute the power evenly on the PCB circuit board as much as possible, and keep the surface temperature performance of the PCB circuit board uniform and consistent. It is often difficult to achieve a strict uniform distribution during the design process, but it is necessary to avoid areas where the power density is too high, so as to avoid the hot spots affecting the normal operation of the entire circuit. If necessary, it is necessary to perform thermal performance analysis of the printed circuit. For example, the thermal performance index analysis software module added in some professional PCB circuit board design software can help the designer to optimize the circuit design.

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