The stability of an acidic tin methanesulfonate electrolyte in the presence of a hydroquinone antioxidant

The electrodeposition of tin at a (0.28 cm2) copper surface from 0.014 mol dm−3 SnSO4 and 12.5 vol.% methanesulfonic acid (MSA 1.93 mol dm−3) at 296 K was studied. Hydroquinone concentrations of 0.005, 0.05 and 0.5 mol dm−3 (corresponding to a molar concentration ratio of hydroquinone to stannous ions of 0.36, 3.6 and 36, respectively) were used. Cyclic and linear sweep voltammetry served to characterise the electrochemical behaviour of tin deposition and stripping. The effects of potential sweep rate and electrode rotation speed on the voltammetry were studied. The stability of the electrolyte with storage time was quantified by changes in the limiting current density for tin deposition at a smooth rotating disc electrode and the peak current density at a static disc electrode. The influence of hydroquinone on mass transport controlled tin deposition and suppression of hydrogen evolution was evaluated.