When the PCB is working, a certain amount of heat will be generated, so that the internal temperature of the device will 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 decline.
Therefore, it is very important to dissipate heat on the circuit board.
However, as electronic products have entered the era of miniaturization of components, high-density installation, and high-heat-generation assembly, it is not enough to rely on the surface of components with very small surface area to dissipate heat.
At the same time, due to the large-scale use of surface-mounted components such as QFP and BGA, the heat generated by the components is transferred to the PCB board in a large amount. Therefore, the best way to solve the heat dissipation is to improve the heat dissipation capacity of the PCB itself that is in direct contact with the heating element. conduct or emanate.
Devices that are more sensitive to temperature are best placed in the area with the lowest temperature (such as the bottom of the device). Never place it directly above the heat-generating device. Multiple devices are best staggered on a horizontal plane.
- Place the devices that consume the most power and generate the most heat near the best heat dissipation locations. Do not place high-heat components on the corners and 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 adjust the layout of the printed board so that there is enough space for heat dissipation.
- High-heat-generating devices plus radiator and heat-conducting plate. When there are a few devices in the PCB that generate a large amount of heat (less than 3), a heat-sink or heat-conducting pipe can be added to the heat-generating device. When the temperature cannot be lowered, use Radiator with fan for enhanced cooling.
When there are many heat-generating devices (more than 3), a large heat-dissipating cover can be used. It is a special heat-sink customized according to the position and height of the heat-generating devices on the PCB or cut out on a large flat-plate heatsink. Different component height positions. Fasten the heat dissipation cover on the component surface as a whole, and contact with each component to dissipate heat.
However, the heat dissipation effect is not good due to the poor consistency of the components during assembly and welding. Usually, a soft thermal phase change thermal pad is added to the component surface to improve the heat dissipation effect.
- For equipment cooled by free convection air, it is best to arrange the integrated circuits (or other devices) in a vertical arrangement or a horizontal arrangement.
- Use reasonable trace design to achieve heat dissipation. Because the resin in the plate has poor thermal conductivity, and copper foil lines and holes are good conductors of heat, improving the residual rate of copper foil and increasing thermal vias are the main means of heat dissipation. To evaluate the heat dissipation capability of the PCB, it is necessary to calculate the equivalent thermal conductivity of the composite material composed of various materials with different thermal conductivity—the insulating substrate for PCB.
- 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.) The uppermost stream (at the inlet), the devices with high heat generation or good heat resistance (such as power transistors, large-scale integrated circuits, etc.) are placed in the most downstream of the cooling airflow.
- In the horizontal direction, the high-power devices are arranged as close to the edge of the printed board as possible to shorten the heat transfer path; in the vertical direction, the high-power devices are arranged as close to the top of the printed board as possible to reduce the temperature impact of these devices on other devices. .
- The heat dissipation of the printed board in the equipment mainly depends on the air flow, so the air flow path should be studied in the design, and the device or printed circuit board should be reasonably configured.
When air flows, it always tends to flow where the resistance is small, so when configuring components on a printed circuit board, it is necessary to 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.
- Devices that are more sensitive to temperature are best placed in the area with the lowest temperature (such as the bottom of the device). Never place it directly above the heat-generating device. Multiple devices are best staggered on a horizontal plane.
Place the devices that consume the most power and generate the most heat near the best heat dissipation locations. Do not place high-heat components on the corners and 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 adjust the layout of the printed board so that there is enough space for heat dissipation.
- Avoid the concentration of hot spots on the PCB, distribute the power evenly on the PCB board as much as possible, and keep the temperature performance of the PCB surface uniform and consistent.
Wonderful PCB You can send us your requirements first, we will reply you as soon as possible. Click here to contact us.
You can click on our component store. Click here to contact us.
English