A modified mixed-mode bending specimen for the interfacial fracture testing of dissimilar materials

This paper presents the results of a combined experimental and analytical/computational study of interfacial fracture between dissimilar materials. Analytical expressions are derived for the computation of strain energy release rates and mode mixities in a new dissimilar mixed-mode bending (DMMB) specimen. The energy release rates are compared with numerical results obtained from finite element analysis of interfacial cracks in a model copper/moulding compound system that is used commonly in electronic packages. Interfacial fracture toughness in this system is shown to increase with increasing mode mixity, for mode mixity levels between pure mode I and pure mode II. The potential applications of the DMMB are also discussed.