Optimization design technique of circuit board heat dissipation

For electronic equipment, working will produce a certain amount of heat, so that the internal temperature of the equipment rises rapidly, if the heat is not dissipated in time, the equipment will continue to heat up, devices will fail due to overheating, and the reliable performance of electronic equipment will decline. Therefore, it is very important to have a good heat dissipation treatment on the circuit board. The heat dissipation of circuit board is a very important link, and then Shenzhen PCBA processing manufacturer - kingford to introduce the optimization design skills of circuit board heat dissipation.

1. The PCB itself dissipates heat

At present, PCB board is widely used in copper/epoxy glass cloth substrate or phenolic resin glass cloth substrate, there is a small amount of paper coated copper board. Although these substrates have excellent electrical properties and processing properties, but poor heat dissipation, as a heat dissipation way of high heating components, almost can not be expected from the PCB resin conduction heat, but from the surface of the components to the surrounding air heat dissipation. However, as electronic products have entered the era of component miniaturization, high-density installation and high thermal assembly, it is not enough to only rely on the surface of components with very small surface area to dissipate heat. At the same time, due to the large number of surface mounted components such as QFP, BGA, the heat generated by components to PCB board, therefore, the best way to solve the heat dissipation is to improve the heat dissipation capacity of PCB in direct contact with the heating element, through the PCB board conduction out or out.

2. High heating device with radiator, heat conduction plate

When the heat of a few components in PCB is large (less than 3), a radiator or heat conduction tube can be added to the heating component. When the temperature can not be lowered, a radiator with a fan can be used to enhance the heat dissipation effect. When the amount of heating devices is large (more than 3), you can use a large heat sink (plate), which is customized according to the position and height of the heating devices on the PCB board, or in a large flat radiator cut out different positions of the components. The radiator cover is fastened on the component surface as a whole, and contact with each component to dissipate heat. However, due to the low consistency of components during welding, the heat dissipation effect is not good. Soft thermal phase change pads are usually added on the surface of components to improve the heat dissipation effect.

3. For the use of free convection air cooling equipment, it is best to arrange integrated circuits (or other devices) in a longitudinal way, or in a transverse way.

SMT patch

4. Adopt reasonable cabling design to dissipate heat

Because the resin in the plate has poor thermal conductivity, and the copper foil line and hole are good conductors of heat, so improving the copper foil residual rate and increasing the heat conduction hole is the main means of heat dissipation. To evaluate the heat dissipation capacity of PCB, it is necessary to calculate the equivalent thermal conductivity of PCB insulating substrate, which is composed of various materials with different thermal conductivity.

5. The devices on the same PCB board should be arranged according to their heat value and heat dissipation degree as far as possible. The devices with small heat value or poor heat resistance (such as small signal transistors, small-scale integrated circuits, electrolytic capacitors, etc.) should be placed at the upper stream (entrance) of the cooling air flow. Devices with high calorific value or good heat resistance (such as power transistors, large-scale integrated circuits, etc.) are placed at the downstream of the cooling flow.

6. In the horizontal direction, the high-power devices should be arranged as close to the PCB board edge as possible, so as to shorten the heat transfer path; In the vertical direction, the high-power components are arranged as close as possible to the top of the PCB board, so as to reduce the influence of these components on the temperature of other components.

7. The heat dissipation of PCB 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. Air flow always tends to flow where the resistance is low, so when configuring components on the printed circuit board, avoid leaving a large area of airspace. The configuration of multiple printed circuit boards in the whole machine should also pay attention to the same problem.

8. More sensitive to temperature of the device is best placed in the lowest temperature area (such as the bottom of the equipment), do not put it on the heating device is above, multiple devices are best in horizontal staggered layout.

9. Arrange the devices with the highest power consumption and maximum heat dissipation near the optimal position for heat dissipation. Do not place hot components at the corners and edges of the PCB board unless there is a cooling device near it. When designing the power resistance, choose a larger device as much as possible, and adjust the PCB layout so that it has enough space for heat dissipation.

10. Avoid the concentration of hot spots on the PCB, distribute the power evenly on the PCB board as far as possible, and maintain the uniform and consistent temperature performance of the PCB surface. Often in the design process to achieve strict uniform distribution is more difficult, but we must avoid the power density is too high in the area, so as to avoid the occurrence of hot spots affect the normal operation of the entire circuit.

Why do you choose kingforfd for PCBA processing?

1. Strength guarantee

▪SMT workshop: We have imported SMT machines and several sets of optical inspection equipment, with a daily output of 4 million. Each process is equipped with QC personnel, who can keep an eye on product quality.

▪DIP production line: We have two wave-soldering machines, among which there are more than 10 old employees who have worked for more than three years. The skilled workers can weld all kinds of plug-in materials.

2. Quality assurance, cost-effective

▪ High-end equipment can stick precision shaped parts, BGA, QFN, 0201 materials. Can also template patch, loose material hand.

▪ Sample and size batch can be produced, proofing from 800 yuan, batch 0.008 yuan/point, no start-up fee.

3. Rich experience in SMT and welding of electronic products, stable delivery

▪ Accumulated SMT SMT processing services for thousands of electronic enterprises, involving many kinds of automotive equipment and industrial control motherboard. The products are often exported to Europe and the United States, and the quality can be affirmed by new and old customers.

▪ On time delivery, normal 3-5 days after complete materials, small batch can also be expedited on the same day shipment

4. Strong maintenance ability and perfect after-sales service

▪ Experienced maintenance engineers can repair all kinds of patch welding caused by bad products, to ensure the connection rate of each piece of circuit board.

▪ 24-hour customer service staff at any time response, the fastest speed to solve your order problems.