The influence of a perfluorinated cationic surfactant on the electrodeposition of tin from a methanesulfonic acid bath

The influence of a perfluorinated, cationic surfactant on the electrodeposition of tin onto a copper surface was investigated. The electrolyte was 0.014 mol dm−3 SnSO4, 0.005 mol dm−3 hydroquinone and 12.5 vol.% methanesulfonic acid (1.93 mol dm−3 MSA) at 296 K, containing a controlled concentration (0–2.4 vol.%) of DuPont™ ForaFac® 1098 surfactant, corresponding to a concentration ratio of surfactant to stannous ions of 0–5.6. Cyclic (at static disc electrode) and linear sweep voltammetry (using the rotating disc electrode) were used to characterise the electrodeposition. The effects of potential sweep rate and electrode rotation speed are discussed. The influences of the surfactant on the region of complete mass transport control and hydrogen evolution are investigated. The effect of surfactant addition to the electrolyte was shown to be potential and flow-dependent. The absorption of surfactant on the electrode surface hindered the hydrogen evolution and resulted in a reduction in the peak and limiting current densities. The reduction of dissolved oxygen from the background electrolyte, in the presence or absence of surfactant, was also investigated. The morphology of electrodeposited tin is characterised; in the presence of surfactant, a compact surface morphology whereas rod-like deposits could be obtained at higher current densities.