Studies on the electrodeposition of tin from acidic chloride–gluconate solutions

Electrodeposition of tin from acidic chloride–gluconate baths was investigated. Equilibrium distribution of tin(II) species showed domination of Sn(II)–gluconate complexes, but for Sn2+ concentrations 50 mM or higher increased percentage of Sn(II)–chloride complexes was found. Cyclic voltammetry, anodic stripping analysis and potentiostatic measurements indicated that rate of the cathodic process is determined by the release of metal cations from gluconate complexes in diluted bath (5 mM), but for more concentrated solutions reduction of Sn(II) ions run under diffusion control. Studies of anodic response showed that it depends on the Sn(II)/Glu ratio in the bath and deposition potential due to development of different planes of metal crystal. Average effective diffusion coefficients of metal species were determined. Morphology and structure tin deposits were also presented.