Study of the deposition mechanisms of passivation layers onto electrodeposited copper foils

Abstract

This work, investigates the passivation of electrodeposited (ED) copper foils using single-element passivation baths of Ni, Cr and Zn. Passivation is the final production step, essential for long-term oxidation protection and preservation of the foil’s high performance. The ED copper coatings were characterized by SEM for morphology and uniformity and by ICP-OES for quantitative analysis of the deposits; in addition, substrate roughness was measured to assess its influence on metal deposition. The influence of duration and current density on electrodeposited nickel coatings was examined. No visible when varying the substrate roughness was seen. Chromium deposition proved to be challenging, with a passivation layer forming and preventing high deposition amounts. When results were put in regard of the profilometry of the underlying foil, the roughness tended to not play a major role. A reverse pulse deposition technique was implemented place to overcome this limitation but ultimately proved unsuccessful under experimental conditions, shifting focus to zinc. Zinc deposition was the most thoroughly studied element, with a monolayer deposition test, temperature and pH changes, as well as a comparison between a passivation made at the laboratory and one taken from a production sample to assess the impact of annex ions on deposition. Moreover, foils with lower initial roughness exhibited higher zinc content, demonstrating that substrate topography significantly influences passivation of copper foils when using zinc. .