Physicochemical-microstructural approach for modeling the crack passage at topside metallic parts in IGBT semiconductor power electronics

Insulated-gate bipolar transistors (IGBTs) are widely used components in power electronics applications. Upon operation, the difference in thermal expansion coefficients of materials composing the upper metallic parts causes thermal fatigue. The latter leads to degradations at metallic topside interconnections through the formation of cracks [1]. This paper focuses on a new physicochemical-microstructural approach for modeling the crack propagation at the contact interface between wires and metallization layers in a power module to answer the following question: what is the preferential crack path along with the interface, and what are the influencing parameters? The model is based on a cohesive zone model (CZM) approach [2] in the vicinity of the contact, used for predicting the crack propagation pathway in a small interfacial region on either sides of a contact. To achieve such predictability, CZM parameters are linked to physicochemical-microstructural properties, i.e., the crack propagation is interpreted at the metallic contact zone based on this linkage. Therefore, this work's originality lies in combining a fracture mechanics approach and a physicochemical-microstructural one.