Electrochemical plating of Cu-Sn alloys for Ni-free in acid based non-cyanide solution

초록

Nickel (Ni) is mainly used as the undercoat material which is the necessary layer in the many decorative and some technical application. However, Ni caused allergies and skin problems induced by elution of metal ion. Therefore, Cu-Sn layers are considered as the substitutes to avoid the use of Ni. In addition, industrial electroplating is still performed from solutions containing cyanide (CN-). Due to the strict environmental regulations, cyanide solution could not be use any longer because of its toxicity. In this study, we propose the best conditions for co-deposition of Cu and Sn in acid based non-cyanide solution. The electrochemical characteristics of Cu, Sn and Cu-Sn alloy were obtained by using rotating disk electrode (RDE) under static and under controlled flow conditions. The effect of Cu ion, Sn ion and additives/surfactant were investigated as well. Furthermore, Cu-Sn alloy were deposited over a range of operating conditions to produce white and bright surface. Finally, morphologies and chemical compositions of Cu-Sn alloys were evaluated by SEM, EDS, XRD, and XPS analysis.