抄録
Various compositions of tin-zinc alloy deposits were obtained from tetrafluoroborate baths. The corrosion resistance and solderbility of these deposits were studied and the following results were obtained:
(1) The deposit on steel substrate containing about 80% of Sn, which had been obtained from the bath containing a brightener, had the highest corrosion resistance; and the same deposit of 10μ in thickness, which had been treated with choromate solution, did not tend to rust after 3000-4000hrs. of continuous salt spray test.
(2) The alloy deposit on steel or copper plating substrate containing about 60-80% of Sn, which had been obtained from the same bath, had the highest solderbility; and the same deposit treated with chromate solution had a slightly less solderbility.
(3) The composition of these alloy deposits from these baths depended upon the ratio of metallic ion concentrations between the components and concentration of tetrafluoroboric acid in the bath and current density. However, there was not a great change in the composition when the deposits had been obtained from a bath containing 70-80% of Sn in which the concentration of tetrafluoroboric acid and current density were kept constant. Accordingly, it was known that the alloy deposits containing about 80% of Sn and having highest corrosion resistance and solderbility were obtained from the above bath.
