Research On Intelligent Power Module Reliability With Fea Method

Intelligent Power Module(IPM), a new generation of power device, is being widely accepted and used. Compared with the traditional power module, the new one applies circuit protection, and encapsulates control IC like under-voltage lock-out and short-circuit protection in IGBT chips, further enhancing the module reliability.This paper researches the new intelligent power module FSBB30CH60 F made by Fairchild Company, using the method of multiphysics coupling simulation.by ANSYS Workbench. The materials used in the research meet the actual and the simulation needs. Anand model is used to describe the viscoelasticity of the solder layer. Thermal- stress coupled power cycle test complies with JEDEC standard.For loading parameters, the junction temperature and the equivalent stress increase along with the increase of the power dissipation, and the maximum stress occurs at the chip corners. The cycle time of the module has little effect on junction temperature and stress, and plastic strain is reduced with the cycle increases in the same simulation time. What’s more, there is a significant inverse correlation between the strain energy and the cycle time.For the procedure parameters, the solder thickness of the module affects the heat-mechanical properties in many ways. With a low thermal conductivity, the thicker the solder layer is, the higher junction temperature the chip will have, and the lower the chip reliability will be. The thicker solder layer, however, can provide a greater range of strain to reduce the stress concentration of the chip. Physical Properties is the main criterion for ceramic material. The main impact of the solder layer void on the reliability is to increase the contact resistance and cause a higher chip junction temperature. Some voids in special positions can easily lead to stress concentration. In short, void should be avoided in any cases.