Lifetime Evaluation of IGBTs Under PWM by a Physical Iterative Simulation Loop Based on the Crack Initiation and Propagation in Chip Solder Layer

Solder fatigue is quite important for the reliability of IGBTs under thermal cycling. In this work, a Finite Elements Analysis-Fatigue Damage Calculation/Feedback (FEA-FDC) iterative looping was proposed for the evolution of micro-cracks in the solder layer of IGBTs. Secondly, the crack initiation and propagation in chip solder layer was investigated under power cycling (PC) by the iterative looping. Furthermore, the crack initiation and propagation in chip solder layer under lower temperature swings (<20K) was investigated. Finally, the degradation in thermal characteristics of IGBTs under PWM operations was evaluated and then a fatigue lifetime prediction method of IGBT under lower temperature swings was proposed. This work may provide a new insight for evaluating the reliability of IGBTs under their normal operating.