Electrochemical deposition of gold–tin alloy from ethylene glycol electrolyte

Abstract

The possibility of Au–Sn alloy deposition from the ethylene glycol electrolyte has been shown. Deposited alloys contain 27–54 at.% of tin and include AuSn 2, Au 5Sn, AuSn crystalline phases together with amorphous gold. The coatings consist of tightly packed submicron grains grown up into agglomerates 2–4 μm in diameter. The rate of the alloy deposition can be varied from 1 to 5 μm h − 1 at current density 5–50 mA cm − 2 . The process of Au–Sn electroplating is characterized by the absence of noticeable cathode passivation, diffusion limitations and hydrogen reduction. The rate of electrodeposition is greatly dependent on Au(III) and Sn(IV) concentration in solution that allows to control Au:Sn ratio in the alloy.