An X-ray study on the mechanical effects of the peel test in a Cu/Cr/polyimide system

In order to understand the effects of plastic deformation and the interfacial fracture energy on the peel strength, thickness of the metal layer and the pretreatment conditions of polyimide were varied in the Cu/Cr polyimide system. The work expenditure during the peel test was estimated using the stress-strain curves of metal films, X-ray measurements of the plastic strain in peeled films, and the elastoplastic beam analysis. Results indicate that the peel strength is strongly affected by the film thickness and the pretreatment condition in a synergistic way, and that the peel strength shows a maximum at an intermediate thickness level. The estimated work expenditure was close to measured peel strength for most of the cases, which indicates that the measured peel strength is more a measure of the plastic deformation during the peel test than a measure of the true interfacial fracture energy. (C) 1997 Acta Metallurgica Inc.