Thermomechanical Fatigue Damage Model of a Solder Joint in Electronic Devices: An Interval Arithmetic Based Approach

This paper presents a new opened-up reliability assessment framework and demonstrates the feasibility of using interval arithmetic by considering degradation and uncertainties effects. Instead of obtaining an unrealistic lifetime estimation, an interval useful lifetime estimation (i-ULE) expressing the possibility of a bound value for the lifespan of a power electronic system is defined. To gain an understanding of the open question, a DC–DC boost converter of 3000 W and 200/400 V is considered as a case study for electric vehicle applications. The study presents the significant self- and mutual-degradation effects on the reliability assessment by proposing and implementing an online junction temperature monitoring of insulated-gate bipolar transistors (IGBT) and diodes in the considered power converter. These effects are discussed through the proposed interval reliability assessment via performing power cycling accelerated aging tests on 32 IGBTs and 32 diodes. It reveals that there is a 27% difference in the global system useful lifetime estimation which can be evaluated with the proposed interval reliability assessment.