The electrodeposition of Cu-Sn-Zn coating on Cu substrate at ambient temperature was investigated. The bath consists of metal salts CuSO4,5H2O, SnSO4, ZnSO4,7H2O and sodium citrate (NaC6H5Na3O7,2H2O) as complexing agent. To prevent precipitation, we varied the pH between 4 and 5.5. The voltammetric curves show four waves clearly defined corresponding to copper, tin and zinc reducing through Cu2HCit2 3-, Sncit2- and ZnHcit- complex respectively, the fourth peak being the reduction of protons. The influence of the concentration of the various bath constituents and the potential scan rate on the voltammetric curves was studied. We have shown that the deposition process of copper and tin is controlled by species mass transfer. For zinc deposition, the mechanism would be controlled by a mixed process: charge transfer and mass transport.
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