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The heat dissipation technique of PCB circuit board
- May 16, 2017 -

For electronic equipment, work will produce a certain amount of heat, so that the equipment internal temperature rises rapidly, if the heat will not be circulated in time, the equipment will continue to heat up, the device will be overheating and failure, the reliability of electronic equipment will be reduced. Therefore, it is very important to have a good thermal treatment of the circuit board. The next branch friend Circuit for everybody to explain about PCB circuit board heat dissipation way.
1. Through the PCB itself heat dissipation: the current widely used PCB board is copper/epoxy glass cloth substrate or phenolic resin glass cloth substrate, there are a small amount of paper-based copper clad laminate. Although the substrate has excellent electrical properties and processing performance, but poor heat dissipation, as the heat dissipation way of high heating elements, it can hardly be expected to transmit heat from the PCB itself, but to heat dissipation from the surface of the component to the ambient air. However, as electronic products have entered into the miniaturization of components, high-density installation, high Fever assembly era, if only the surface of very small components to heat dissipation is very insufficient. At the same time because of the QFP, BGA and other surface installation components of a large number of use of the heat generated by the PCB board, so the best way to solve the heat dissipation is to improve the direct contact with the heating elements of the PCB itself, through the PCB conduction out or out.
2. For equipment using free convection air cooling, it is preferable to arrange integrated circuits (or other devices) by longitudinal length or by transverse length.
3. Adopt reasonable line design to realize heat dissipation: due to the poor thermal conductivity of the resin plates, and copper foil wiring and holes are hot good conductors, so improve the residual rate of copper foil and increase the guide Gecon is the main means of cooling.
4. High heating device plus radiator, heat conduction board: When the PCB has a small number of devices calorific value (less than 3), the heating device can be added to the radiator or heat pipe, when the temperature can not fall down, the radiator may be used with a fan to enhance the cooling effect. When the heating device is more (more than 3), can use a large heat sink (plate), it is on the PCB board heating device position and high and low customized special radiator or a large flat plate radiator to pull out different components of high-low position. The heat sink integrally buckle on the component surface, contact with each component heat dissipation. However, because of the high and low consistency of components welding, the heat dissipation effect is not good. Usually on the components surface with a soft thermal phase change heat conduction pad to improve the cooling effect.
5. In the horizontal direction, high-power devices as close as possible to the edge of the PCB layout, in order to shorten the heat transfer path; In the vertical direction, high-power devices as far as possible close to the PCB layout, so as to reduce the work of these devices on other device temperature impact.
6. The device on the same printed board should be arranged as far as possible according to its calorific value and the heat dissipation degree partition, small or heat-resistant devices (such as small signal transistors, small-scale integrated circuits, electrolytic capacitors, etc.) are placed in the most high (entrance) of the cooling airflow, large or heat-resistant devices (such as power transistors, LSI, etc.) are placed at the downstream of the cooling airflow.
7. Temperature-sensitive devices are preferably positioned in the lowest temperature areas (such as the bottom of the device), and do not put it on the top of the heating device, a number of devices preferably in the horizontal plane staggered layout.
8. The most power-consuming and heating device is arranged near the optimum heat dissipation position. Do not place high fever devices in the corners and edges of the printed boards unless there is a cooling device arranged around it. When designing a power resistor, select the larger device as much as possible, and have sufficient heat dissipation space when adjusting the layout of the printed board.
9. The heat dissipation of printed boards in the equipment depends mainly on the air flow, so the air flow path is studied at design time, the device is configured rationally or printed circuit boards. Air flows always tend to flow in small areas where resistance, so when configuring devices on a printed circuit board, avoid having a larger airspace in a region. The same problem should be noticed in the configuration of multiple printed circuit boards in the whole machine.
10. Avoid the hot spots on the PCB, as far as possible to distribute the power evenly on the PCB board, to maintain the PCB surface temperature performance uniformity and consistency. Often in the design process to achieve a strict uniform distribution is more difficult, but must avoid the high power density of the area, so that there is a hotspot to affect the entire circuit of normal work. If there is a condition, the thermal efficiency analysis of the printed circuit is very necessary, such as some professional PCB design software to increase the thermal efficiency Index analysis software module, can help designers optimize the circuit design.