Analysis of Transient Thermal Stress of IGBT Module Based on Electrical-Thermal-Mechanical Coupling Model

Reliability of IGBT power module is one of the biggest concerns regarding wind power system, which generates the non-uniform distribution of temperature and thermal stress. The effects of non-uniform distribution will cause failure of IGBT module. Therefore, analysis of thermal mechanical stress distribution is crucially important for investigation of IGBT failure mechanism. This paper uses FEM method to establish an electrical-thermal mechanical coupling model of IGBT power module. Firstly, thermal stress distribution of solder layer is studied under power cycling. Then, the effects of initial failure of solder layer on the characteristic of IGBT module is investigated. Experimental results indicate that the strain energy density and inelastic strain are higher which will reduce reliability and lifetime of power modules.