Cohesive zone experiments for copper/mold compound delamination

As complex multi-layered packaging becomes more common in microelectronic design, delamination remains a prominent failure mechanism due to coefficient of thermal expansion mismatch. Numerous studies have investigated interfacial cracking in microelectronic packages. These studies commonly use classical interfacial fracture mechanics analyses, but such analyses require knowledge of starter crack size, locations, and propagation paths. Cohesive zone theory has been identified as an alternative method for modeling crack propagation and delamination without the need for a pre-existing crack. This paper presents a framework to determine mixed-mode cohesive zone parameters using experimental methods. We demonstrate this method by characterizing cohesive zone parameters for a copper/epoxy molding compound interface. Fully characterized cohesive zone elements can be placed at interfaces in finite-element models of microelectronic systems to simulate loading and failure in mixed-mode conditions.