Abstract
Engine control units or power control unit are key technologies for new vehicles like hybrid cars, electric cars and hydrogen-fuel cell vehicles. These power devices must be protected by plastic packages from circumstances. However, severe circumstances in engine rooms cause delaminations between components in the plastic packages. In this study, we evaluated the stress intensity factors of a corner and a small crack along the interface between molding resin and a substrate in the plastic package of a power devise. Stress intensity factors of a corner were useless because the order of stress singularities of a corner change with temperature and the combination of components. However, evaluated stress intensity factors of a crack on the interface can evaluate the strength of the interface between molding resin and a substrate reasonably.
