Electro-thermo-mechanical Coupling And Failure Analysis Of IGBT Module

In recent years, with the rapid development of new energy power generation, rail transportation, smart grid, electric vehicles and other emerging industries, IGBT module has been widely used. With the development of renewable energy technology, the requirements of reliabilities of power converters become higher. As the core devices of power converters, the reliability of IGBT module has been paid more and more attention. The existing researches show that the bad working environment accelerates the aging and failure of the device, so the research on the aging and failure mechanism of IGBTs module becomes more and more urgent. In this paper, combining with the actual situation, theoretical analysis and simulation, the reliability analysis of IGBT module is carried out by using the method of multi-physical coupling analysis. There are two main aspects of the research results:The electro-thermo-mechanical coupling physical model of IGBT is established by taking the bonding wire of the IGBT module as the research object. By comprehensively analyzing of the temperature and stress of the bonding wires on normal condition and partial bonding wires failure, it is pointed out that the shear stress is the direct cause of the fatigue and failure of the bonding wires and the main form of bonding wire failure is bonding wires off. Copper bonding wire has better electrical, thermal and mechanical properties than traditional aluminum bonding wire. Copper bonding wire model is established and copper bonding wire can improve the reliability of the module by simulation.The thermo-mechanical coupling physical model of IGBT is established by taking the solder layer of the IGBT module as the research object. By comprehensively analyzing of the temperature and stress of the bonding wires on no void and voids in different positions, it is pointed out that the solder layer is easy to produce crack at the edge of the corner and lead to stratification. Solder layer voids affect the temperature distribution of the module, resulting in local high temperature, hot spot and burned device. In this paper, the simulation of the module in the temperature cycle and power cycle is carried out and the thermal resistance of the module is fitted. The results show that the temperature fluctuation of the module changes with the temperature of the environment under the temperature cycle. When the working frequency of IGBT is low under power cycle, the junction temperature fluctuates greatly, it is easy to produce thermal shock, which is caused by the failure of the solder layer and IGBT module. In the practical work, it should pay attention to the fluctuation of the junction temperature in the low frequency of the IGBT module to reduce the adverse effect of the thermal shock on the life of the IGBT module.