How to improve the thermal reliability of PCB circuit board
Update Time ： 2017-05-04 View ： 2348
In general, the distribution of copper foil on the PCB circuit board is very complex, it is difficult to accurately model. Therefore, when modeling need to simplify wiring shape, make the electronic components and the ANSYS model of circuit board actual circuit board close can also be used to simplify the modeling simulation, such as MOS tube, integrated circuit block etc..
thermal analysis
The thermal analysis of the patch can assist the designer to determine the electrical performance of the components on the PCB circuit board, and help the designer to determine whether the component or circuit board will burn out because of the high temperature. Simple thermal analysis is to calculate the average temperature of the circuit board, the complexity of the circuit board with a number of electronic equipment to establish a transient model. The accuracy of thermal analysis depends on the accuracy of the power consumption of the circuit board designers.
In many applications the weight and physical size is very important, if the actual power consumption component is very small, may cause the design safety factor is too high, so that the circuit board design was inconsistent with the actual or conservative power consumption value as according to the thermal analysis. On the contrary (and more severe) is the thermal design of safety coefficient is too low, the actual element operating temperature than analysts predicted to be high, such problems should be solved by general add a cooling fan to cool a device or circuit board. These external accessories increase the cost, but also prolong the time of * * in the design, with the fan will bring instability to the reliability, so the circuit board mainly adopts active rather than passive cooling methods (such as natural convection, conduction and radiation).
Simplified modeling of PCB
What are the major heating elements in the circuit board, such as MOS and integrated circuit blocks, which are used to convert most of the loss power into heat. Therefore, these devices need to be considered when modeling.
In addition, consider the circuit board substrate, as the conductor coated copper foil. They are in the design not only played the role of conductivity, but also play the role of heat conduction, the thermal conductivity and heat transfer area are relatively large circuit board is part of an electronic circuit, which is composed of epoxy resin coated copper wire as substrate and composition. The thickness of the epoxy resin is 4mm, and the thickness of the copper foil is 0.1mm. The thermal conductivity of copper is 400W/ (M DEG C), while the thermal conductivity of epoxy resin is only 0.276W/ (M C). Although the copper foil is very thin and thin, it has a strong guiding effect on heat, so it can not be ignored in modeling.
