Reliability of Power Modules in Hybrid Vehicles

The life time of a component is defined by the reliability demands place on it due to its operating environment and operation conditions. To evaluate the necessarily thermal / power cycle stability of a power semiconductor module in a hybrid electrical vehicle (HEV), a vehicle driving cycle profile is used to calculate the thermal reliability requirements. The calculations are based on power loss calculation, thermal modeling and a general approach of a life cycle model. This paper discusses the reliability requirements due to active and passive thermal stress on various joints such as solder or bond joints resulting by using different connections of a power module to varied cooling systems.