Mode Mixity Dependency on Fatigue Crack Propagation for an Epoxy molding Compound/Copper Interface

Citation: 
Samet, D., Rambhatla, V. N. N. Trilochan,, and Sitaraman, S.K, “Mode Mixity Dependency on Fatigue Crack Propagation for an Epoxy molding Compound/Copper Interface”, TECHCON, Austin, TX, Sep. 2017
Abstract: 
Interfacial crack propagation for metal-polymer interfaces is an important area of study for microelectronic package reliability. Interfacial delamination has been studied with both traditional fracture mechanics and cohesive zone modeling (CZM) approaches. Unlike traditional linear elastic fracture mechanics (LEFM) based simulations; CZM can predict both the initiation and propagation of a crack without requiring an initial crack. The authors have developed a fatigue compatible CZM approach enabling a computationally affordable model incorporating fatigue effects for such interfaces. The energy decrement method (EDM) modifies the CZM traction-separation laws to model fatigue crack propagation in an energy conservative manner. As the adhesion strength of bimaterial interfaces is a function of mode mixity, the mode mixity dependency of the fatigue crack growth relationships must be explored to establish an accurate generalized numerical model. This work presents preliminary fatigue results for an epoxy molding compound/copper interface under different mode mixity conditions.
Link to Paper: 
https://www.src.org/library/publication/p091318/