Electrodeposition of copper – tin alloys from glycol electrolytes

Abstract

Stable ethylene glycol (EG) and propylene glycol (PG) electrolytes containing СuCl2 · 2H2O, SnCl4 · 5H2O and Trilon B have been developed, which provide electrodeposition of Cu – Sn alloy with tin content varying from 34 to 52 at. % in case of EG and from 51 to 91 at. % in case of PG electrolytes. It is found that the coatings contain phases of Cu6Sn5 и Cu10Sn3 intermetallic compounds, and metallic tin is also present in case of its highest content in the alloy. It is revealed that tin content can be simply varied by the change of current density or concentrations of tin and copper compounds in glycols. The effect of electrolyte composition, deposition conditions, a nature of a substrate on the coatings deposition rate (in the limits of 0.9‒2.9 μm ∙ h‒1), total metal current efficiency (from 40 to 95 %), the ratio of metals in the alloy (from 34 to 91 at. %), its phase composition and microstructure is determined. The conditions for the deposition of Cu – Sn alloy close to the eutectic composition have been found.

Keywords

• electrochemical deposition
• alloy
• copper
• tin
• eutectic
• glycol electrolyte
• elemental and phase composition
• microstructure