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.