Polymeric coatings on copper surfaces are known to degrade at a faster rate than identical materials on other metals such as aluminum, particularly during thermal aging. We have studied the interfacial reactions occurring at copper surfaces coated with poly(esterimide) and polyimide wire enamels. Thin coatings (100 Å–1 μm) were heat treated at temperatures from 200 to 240 °C. Interfacial reactions were studied by x-ray photoelectron spectroscopy (XPS), Auger profiling, and reflectance infrared spectroscopy. In addition to copper oxide growth at the interface, thermal oxidative degradation of the polymer leads to thinning of the coating. This reaction is catalyzed by the copper (oxide) surface and material loss occurs primarily at the polymer/copper (oxide) interface. Migration of mobile copper species into the bulk of the coating is observed by its appearance at the surface and by depth profiling. For polyimide films prepared from poly(amide-acid) precursors, an interfacial reaction occurs during initial contact, prior to curing or aging, and infrared and XPS measurements show incomplete curing of the film. The formation of a copper carboxylate is postulated.

Burrell, M. C., Codella, P. J., Fontana, J. A., & Chera, J. J. (1989). Interfacial reactions at copper surfaces coated with polymer films. Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 7(3), 1778–1783.