Thermal fatigue and failure of power device substrates

摘要

Electronic power devices used for transportation applications (automotive and avionics) experience severe temperature variations which promote their thermal fatigue and failure. Under high temperature variations, conditions failure (conchoidal fracture) can occur in DBC substrates. The Weibull approach was used to model the brittle fracture of the ceramic layer from a natural defect. Besides, geometric singularities in the upper ceramic/copper interface are at the origin of cracks, which grow by fatigue and finally bifurcate and break the ceramic layer. With the framework of linear elastic fracture mechan-ics (LEFM) and using the finite element method, it was possible to analyse how a thermal loading his-tory may modify the risk of failure of the DBC substrate and can increase the fatigue life of a power module. This result shows that the fatigue life and the reliability of power electronic devices could be optimized using a thermo-mechanical approach of the problem and suitable failure criteria.