Study on lifetime prediction considering fatigue accumulative effect for die‐attach solder layer in an IGBT module

Abstract An accurate lifetime model is needed in power electronic systems as a cost‐effective means of improving reliability and performance assessment, which have long been highly desired to reduce the maintenance cost and to make the product more competitive in the market. Die‐attach solder layer fatigue has been identified as one of the root causes of failure of power electronic modules. This paper presents “physics‐of‐failure lifetime model”, which takes fatigue accumulative effect into consideration and can quantify the effect of long‐term small‐temperature cycling to device fatigue life cycle to estimate the lifetime of the power module. First, small ΔTjpower cycling tests were designed to obtain the effects of ΔTjon aged and un‐aged modules. They indicated that the traditional lifetime models were not accurate in predicting the lifetime of power modules. Therefore, a new time‐domain crack propagation model based on the cumulative damage in the die‐attach solder layer is proposed, which includes time‐dependent material properties and temperature profiles. Moreover, power cycling experiments and simulations are conducted to demonstrate the method by comparing the number of cycles to failure. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.