Abstract
Tin-antimony alloys were electrodeposited from acidic HEDP solutions containing 1-hydroxyethane-1, 1-diphosphonic acid (HEDP), stannous ions (Sn2+), antimony cations (SbO+), and ammonium ions (NH4+). Plating was conducted under the following conditions: 20±2°C, 2.0±0.1pH, and 10 to 50mA·cm-2 current density with weak agitation. The composition of the tin-antimony alloy deposits was affected by the pH, the metal concentration ratio in the solution, and agitation. The current efficiency tended to decrease with an increase exceeding 20wt % in the antimony concentration in the bath and antimony content of the alloys increased. The codeposition of tin-antimony alloys in a bath with a lower pH was found to be regular type because the antimony content of alloys was higher than that of antimony in the electrolyte. The codeposition changed to potential dependence with increasing pH in the bath, Sn-Sb alloy deposits containing Sb 20wt% to 50wt% were white in appearance and smooth.
