Determination of fracture toughness for metal/polymer interfaces

This work focuses on the interpretation of experimental results obtained from fracture toughness tests conducted for a typical metal/polymer bimaterial interface similar to those encountered in electronic packaging applications. Test specimens,with pre-implanted interfacial cracks were subjected to a series of fracture toughness tests. Interfacial fracture toughness is interpreted from the experimental results as the critical energy release rate (G(c)) at the instant of crack advance. The values of G(c) from the experiments are determined using direct data reduction methods assuming linens elastic material behavior. These G(c). values are compared to critical energy release rate values predicted by closed-form analyses of the tests, and to critical J-integral values obtained from finite-element analyses of the test specimen geometries. The closed-form analyses assume linens elastic material behavior, while the finite-element analyses assume both linear elastic as well as elastic-plastic material behaviors.