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How to solve the thermal reliability problem of circuit boards?

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Update time : 2020-01-09 16:50:47

The thermal reliability of circuit boards has always been the issue that everyone is most concerned about. Today, circuit board manufacturers will talk to you about this issue of circuit boards.

Under normal circumstances, the copper foil distribution on the circuit board is very complicated and difficult to accurately model. Therefore, the shape of the wiring needs to be simplified when modeling, and the ANSYS model close to the actual circuit board should be made as close as possible. The electronic components on the circuit board can also be simulated by simplified modeling, such as MOS tube, integrated

1.Thermal analysis

Circuit board manufacturers introduce thermal analysis to help designers determine the electrical performance of components on a circuit board and help designers determine whether components or circuit boards will burn out due to high temperatures. Simple thermal analysis only calculates the average temperature of the circuit board, while more complicated one needs to establish a transient model for electronic equipment with multiple circuit boards. The accuracy of thermal analysis ultimately depends on the accuracy of component power consumption provided by the board designer.

Weight and physical size are very important in many applications. If the actual power consumption of the component is small, the safety factor of the design may be too high, so that the circuit board design uses the power consumption value of the component that is inconsistent with the actual or too conservative. Perform thermal analysis. In contrast (and more serious), the thermal safety factor is too low, that is, the temperature of the component during actual operation is higher than the analyst predicted. Such problems generally require the installation of a heat sink or a fan on the circuit board. Cool it down. These external accessories increase the cost and prolong the manufacturing time. Adding a fan to the design will also bring instability to the reliability. Therefore, the circuit board mainly adopts active rather than passive cooling methods (such as natural convection, conduction and radiation). Cooling).

2. Simplified modeling of circuit boards

Before modeling, analyze what are the main heating components in the circuit board, such as MOS tubes and integrated circuit blocks, etc. These components convert most of the loss power into heat during work. Therefore, these devices need to be considered when modeling. In addition, it is necessary to consider the copper foil coated as a lead on the circuit board substrate. They not only play a conductive role in the design, but also play a role in conducting heat. Their thermal conductivity and heat transfer area are relatively large. Circuit boards are an indispensable part of electronic circuits. Its structure is made of epoxy resin substrate. It consists of copper foil coated as a lead. The thickness of the epoxy substrate was 4 mm, and the thickness of the copper foil was 0.1 mm.