Influences of composite additives and technological parameters on the microstructure and properties of electrolytic copper foil

Abstract In this paper, the additives consisting of bis‐(3‐sulfopropyl)‐disulfide, hydroxyethylcellulose and collagen additive compounding are used to fabricate ultra‐thin copper foils with low roughness on titanium substrates. The results show that the deposited layers obtained at the electrodeposition time of 3 min, the electrolyte temperature of 50 °C and the output voltage of 2.5 V exhibit small grain size and good adhesion to the substrate. Meanwhile, the effects of the two‐component additive and the three‐component additive on the microstructures, surface roughness and electrochemical behavior of copper foils are studied. The x‐ray diffraction results reveal that copper foils prepared by simultaneous introduction of 0.06 g/L bis‐(3‐sulfopropyl)‐disulfide and 0.08 g/L collagen possess a dense and homogeneous structure with the smallest grain size and the lowest roughness, which is diminished by 26.17 %. The electrochemical results indicated that the SC additive had an inhibitory effect on the deposition of copper ions, while the SH additive exerted depolarizing effect in this electrolyte system, accelerating the deposition of copper particles, which was attributed to the antagonistic interaction between bis‐(3‐sulfopropyl)‐disulfide and hydroxyethylcellulose that hindered the preferential adsorption of the additive at the surface protrusions, resulting in the decrease in the refinement effect of the bis‐(3‐sulfopropyl)‐disulfide additive. Under the optimized process parameters, the increase in the deposition rate of Cu 2+ balances the relationship between nucleation and growth of copper ions, which ultimately produces the copper foil with smooth surface and low roughness.