Electrodeposition of tin-rich Cu-Sn alloys from a methanesulfonic acid electrolyte

A systematic approach for the selection of electrochemical parameters for the electrodeposition of tin-rich copper-tin alloys has been performed. This was enabled by using a Cu:Sn ratio of 1:10 in the electrolyte. The effect of this metal ion ratio in the electrolyte and surfactants on the tin content in the deposit was examined using a rotating disk electrode. Cyclic voltammetry showed that inclusion of surfactant in the electrolyte had no effect on the reduction potential of tin which remained at -0.45 V. However, the reduction potential for copper decreased from -0.13 to -0.18 V, thereby making alloy deposition more facile. Chronoamperometry and anodic stripping voltammetry showed that current efficiency for copper-tin deposition ranged from 92 to 95%. Electrodeposition experiments to obtain high Sn content were carried out at constant current using vitreous carbon electrodes. Deposits containing up to 96 wt% tin were obtained. Cu-Sn alloys consisted of two phases, tetragonal tin and a hexagonal Cu ₆Sn₅ intermetallic compound.