Codeposition of Cu-Sn from Ethaline Deep Eutectic Solvent

Copper and tin have been co-deposited from choline chloride ethylene glycol based deep eutectic solvent (DES) containing CuCl2 center dot 2H(2)O and SnCl2 center dot 2H(2)O. Initially, electrolyte formulation experiments were carried out containing different amounts of copper and tin at a brass cathode in a rotating cylinder Hull cell. It was found that metallic deposits containing copper and tin could be deposited from a DES containing 0.02 M CuCl2 center dot 2H(2)O and 0.1 M SnCl2 center dot 2H(2)O. Polarization scans were carried out to determine the reduction potentials for individual metals and alloys. Anodic stripping voltammetry showed that Sn co-deposits with Cu at -0.36 V, at a lower over-potential than the tin reduction potential. Smooth and bright deposits of thicknesses up to 10 mu m were obtained at a potential of -0.36 V or by using a current density of -0.87 x 10(-3) A cm(-2). XRD analysis showed the formation of mainly Cu3Sn and some Cu5Sn6. Our results suggest that Sn is co-discharged with Cu at potentials which is noble compared to the reduction potential of the individual metal. (C) 2015 Elsevier Ltd. All rights reserved.