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PCB Tech

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PCB Tech

PCB Tech

PCB circuit board heat dissipation skills
2021-10-04
View:25
Author:Downs

The heat generated by the work of the circuit board causes the temperature inside the device to rise 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 reliability of the electronic equipment will decrease. Therefore, it is very important to deal with the heat dissipation of the circuit board.

1. Analysis of temperature rise factors of printed circuit boards

Two phenomena of printed circuit board temperature rise:

(1) Local temperature rise or large area temperature rise;

(2) The temperature rises for a short time or for a long time.

In the analysis of PCB thermal power consumption, it is generally analyzed from the following aspects.

1. Electrical power consumption

(1) Analyze the power consumption per unit area;

(2) Analyze the power distribution on the printed circuit board.

2. The structure of the printed board

(1) The size of the printed board;

(2) The material of the printed board.

pcb board

3. How to install the printed board

(1) Installation method (such as vertical installation, horizontal installation);

(2) The sealing condition and the distance from the casing.

4. Thermal radiation

(1) The emissivity of the printed board surface;

(2) The temperature difference and absolute temperature between the printed circuit board and the adjacent surface;

5. Heat conduction

(1) Install the radiator;

(2) Transmission of other installation structures.

6. Thermal convection

(1) Natural convection;

(2) Forced cooling convection.

2. Circuit board heat dissipation method

1. High-heat equipment, radiators and heat conducting plates

When several devices in the pcb have a large heating value (less than 3), when the temperature has not yet reached, a radiator or a heat pipe can be added to the heating device.

When it can be lowered, a radiator with a fan can be used to enhance the heat dissipation effect. It can be used when the amount of heating device is large (greater than 3).

2. The PCB board itself dissipates heat

At present, the widely used printed circuit boards are copper clad/epoxy glass cloth or phenolic resin glass cloth, and a small amount of paper-based copper clad laminates are also used.

3. Reasonable linear design for heat dissipation

Due to the poor thermal conductivity of the resin in the sheet, copper foil wires and copper foil holes are good heat conductors, increasing the residual rate of the copper foil, and increasing the heat conduction holes is the key to heat dissipation.

The main means.

4. For equipment that adopts free convection air cooling, it is best to set the integrated circuit (or other device) to the longitudinal length or the transverse length.

5. The components on the same printed circuit board should be arranged as much as possible according to the heat generation and heat dissipation degree, and the heat generation is small or the heat resistance is poor.

6. In the horizontal direction, the high-power device is as close as possible to the edge of the printed circuit board in order to shorten the heat transfer path; in the vertical direction, the high-power device

7. The heat dissipation of the printed circuit board mainly depends on the airflow, so the airflow path should be studied in the design, and the device or the printed circuit board should be reasonably configured.

8. Avoid hot spots concentrated on the PCB, distribute power on the PCB as evenly as possible, and maintain the uniformity of the PCB surface temperature performance.

9. Arrange the equipment with the highest power consumption and the highest heat output near the best heat dissipation position. Do not place the heating device at the corner of the printed circuit board.

10. The high heat dissipation device must be able to reduce the thermal resistance between them connected to the substrate. In order to better meet the thermal characteristics requirements, at the bottom of the chip

12. Connection between device and substrate:

(1) Shorten the lead length of the device as much as possible;

 (2) When selecting high-power devices, the thermal conductivity of lead materials should be considered. If possible, the largest cross-sectional surface of lead should be selected as much as possible;

(3) Choose a device with more pins.

13. Packaging options for pcb circuit equipment:

(1) When considering thermal design, pay attention to the packaging instructions of the device and its thermal conductivity.

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

     (3) Air isolation should be avoided in the heat conduction path. If so, it can be filled with a thermally conductive material.