Thermal aging study of encapsulated power devices under autonomous driving condition and its effect on board level reliability

This study presents an investigation of the effect of thermal aging of encapsulated power devices under autonomous driving conditions on the board level reliability. An activation energy-based empirical model to predict the thickness of the oxidized layer in EMC during isothermal aging is proposed, based on the oxidized layer thickness measurement data. A numerical analysis is followed to investigate this effect on solder joint reliability. Two thermal cycling conditions are considered, which simulate the commuting condition and the autonomous driving condition. The results show that, based on the current constitutive properties and modeling approach, solder joint reliability for the two conditions are virtually the same while solder joint reliability of the oxidized package under the autonomous driving condition is reduced significantly. This paper also reports changes in IMC morphology under the two thermal cycling conditions. Significant morphology changes are observed, and these will be incorporated in the prediction of solder joint reliability under autonomous driving conditions in the future study.