Tin-Silver Alloy Electrodeposition from a Concentrated Calcium Chloride Aqueous Solution and Selective Recovery of Metal Components from The Electrodeposition Bath

Abstract

A concentrated calcium chloride（CaCl₂）-based electrodeposition bath was investigated for use in low-toxicity tin-silver（Sn-Ag）alloy plating processes and for facile recovery of metal components from used plating bath（s）. Flat electrodeposition was achieved using a Sn-Ag alloy electrodeposition bath: 5 mM AgCl＋195 mM SnCl₂＋12 mM HCl in CaCl₂･10H₂O. Moreover, a simple pH adjustment and subsequent filtration removed 99% of the silver as precipitate, leaving tin in the solution. Results show that concentrated CaCl₂ aqueous solutions might be used as a Sn-Ag alloy plating bath, thereby facilitating the selective recovery of metal components.