A molecular dynamics study of tensile strength between a highly-crosslinked epoxy molding compound and a copper substrate

Presented in this paper is a numerical study based on classical molecular dynamics simulation to understand the deformation and failure behavior of an epoxy/copper bimaterial under pure tension normal to the interface. The epoxy considered is a highly cross-linked epoxy phenol novolac, and the copper substrate is a standard face-center-cubic single crystal with its (1,1,1) surface as the epoxy/copper interface. Stress versus displacement/strain curves are obtained to understand the bimaterial behavior and to predict the epoxy/copper interfacial tensile strength. It is found that the interfacial failure is brittle caused by simultaneous detachment of epoxy atoms from the copper substrate, and the interfacial tensile strength is almost unaffected by the unloading and reloading before the failure strength is reached. Effects of temperature, epoxy cross-link density, and epoxy functionality are also investigated. Findings of this study provide significant insights into the deformation and failure behavior mechanisms of the epoxy/copper bimaterial interface.