End of life and acceleration modelling for power diodes under high temperature reverse bias stress

Abstract

This work is motivated by the growing importance of lifetime modelling in power electronics. Strongly accelerated High Temperature Reverse Bias (HTRB) testing of power diodes at different stress conditions is performed until alterations and fatigue mechanisms become evident. Two categories of effects can be separated: Drifting breakdown voltage and hard failures with complete loss of blocking capability. Nevertheless the overall stress duration needed to provoke destructive failures is very high with test durations >2500h even at almost 230°C and 100% rated voltage. For both mechanisms the temperature and voltage acceleration is evaluated. Especially temperature acceleration is significant in the regime of testing between 200°C and 230°C and an activation energy Ea in the regime >1eV can be deduced which is higher compared to values commonly reported in the literature. Failure analysis shows that both package and also chip related effects could contribute to the observed hard failures in HTRB stress under extreme conditions.