How to Improve the Thermal Reliability of PCB Circuit Boards

In general, the distribution of copper foil on a pcb circuit board is very complex and difficult to model accurately. Therefore, it is necessary to simplify the shape of the wiring when modeling, and try to make an ANSYS model that is close to the actual circuit board. Electronic components on the circuit board can also be simulated by simplified modeling, such as MOS tubes, integrated circuit blocks, etc.
Thermal analysis Thermal analysis
in chip processing can help designers determine the electrical properties of components on a pcb circuit board, and help designers determine whether components or circuit boards will burn out due to high temperatures. A simple thermal analysis simply calculates the average temperature of the circuit board, while a more complex one involves building a transient model of an electronic device with multiple circuit boards. The accuracy of thermal analysis ultimately depends on the accuracy of the component power dissipation provided by the board designer.
In many applications, weight and physical size are very important, and if the actual power dissipation of the components is very small, the safety factor of the design may be too high, so that the design of the circuit board is based on unrealistic or too conservative component power dissipation values. Perform thermal analysis. On the contrary (and more serious), the thermal safety factor is designed too low, that is, the actual operating temperature of the component is higher than the analyst predicts. Such problems are generally solved by installing a heat sink or a fan to the circuit board. Cool down to resolve. These external accessories increase the cost and increase the manufacturing time. Adding fans to the design can also introduce instability factors in reliability. Therefore, the circuit boards are mainly cooled by active rather than passive methods (such as natural convection, conduction and radiation). heat dissipation).
Simplified modeling
of circuit boards Before modeling, analyze the main heating devices in the circuit board, such as MOS tubes and integrated circuit blocks, which convert most of the power loss into heat during operation. Therefore, these devices are primarily considered for modeling.
In addition, consider the copper foil applied as a wire on the circuit board substrate. They not only conduct electricity in the design, but also conduct heat. Their thermal conductivity and heat transfer area are relatively large. The circuit board is an indispensable part of the electronic circuit. Its structure is composed of epoxy resin substrates. and copper foil coated as a wire. The thickness of the epoxy resin substrate was 4 mm, and the thickness of the copper foil was 0.1 mm. The thermal conductivity of copper is 400W/(m°C), while the thermal conductivity of epoxy resin is only 0.276W/(m°C). Although the added copper foil is very thin and thin, it has a strong guiding effect on heat, so it cannot be ignored in modeling.
As far as the heat resistance is concerned, it is also necessary to understand the heat resistance value of the board. Generally, the heat resistance value of the Kingboard (KB) material on the market is TG130. This is common. If the heat resistance needs to be higher, there is Shengyi TG140. And Shengyi TG170 sheet, unless the heat resistance value requires special requirements, Shengyi TG170 sheet will be used, and Shengyi TG140 sheet is generally used. Now there is a company in the Yangtze River Delta that uses Shengyi TG140, Hangzhou Jiepei, I have made samples here, the price is not much different from the price of Kingboard, and there is no rush fee SF Express , this is also a point that attracts me. Finally, fellow Daoists, there are many board factories in the market, and the water is very deep. You should consider carefully if you need proofing. It doesn't matter if the price is cheap, you just like it. Pindao thinks that the documents he designs hope that the finished product will be perfect, and he does not want to affect his design because of the problem of the board