Electrolytic Chromate Films Prepared via Pulse Electrodeposition as a Cu-Epoxy Adhesion Promoter

Abstract

Chromate films with nanometer-scale thicknesses typically act as secondary adhesive layers between Cu and a polymer film to produce a copper clad laminate (CCL); chromate films provide surface hydroxyl (-OH) that ensures strong binding with the silane coupling agent (primary adhesion promoter). To improve the adhesive strength between Cu and epoxy substrates, in this study, Cr(OH) 3 films with high surface coverages were deposited via the pulse electrodeposition technique. In comparison with conventional direct current modes, pulse plating enables the development of high densities of Cr(OH) 3 nuclei, resulting in a uniform film growth. Thus, the use of pulse plating leads to good coverage of Cr(OH) 3 on a Cu surface, and in turn, a higher peel strength with epoxy, and excellent corrosion protection. These observations indicate that chromate films generated via pulse plating may be a good option for post-treatment of Cu foils to ensure their reliable application for 5 G electronic devices.