Interfacial behavior of polyimide/primer/copper system by preoxidation of the primer

Abstract

The copolymers of vinyl imidazole (VI) and vinyl trimethoxy silane (VTS) were applied as the corrosion inhibitors and the adhesion promoters for the polyimide/ copper system at elevated temperatures. The mol ratios of VI to VTS were 100: 0, 70 : 30, 30: 70, and 0: 100. Preoxidation of the primer was performed to improve the reactivity of the primer on poly(amic acid). A peel test was performed to evaluate the adhesion strength of the polyimide/primer/copper system after heat treatment at 400°C in a nitrogen atmosphere. The effect of the preoxidation of the primer on corrosion protection and adhesion promotion were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The adhesion strength of the polyimide/primer/copper system depended on not only the chemical interaction between polyimide and the preoxidized primer, but also the thermal stability of the primer. It showed the highest value when the mol ratio of VI to VTS was 30: 70. The primer layer reduced or suppressed copper diffusion into the polyimide layer. The degree of corrosion protection by the primer was affected by its thermal stability and its reactivity on copper.