Abstract
The elution of bismuth, silver and tin into acid rain from three kinds of lead-free solder with different melting points (different proportions of bismuth) was investigated and com-pared with that of lead from Sn37Pb solder. The amount of bismuth eluted from lead-free solders ranged from approximately 1/100 to 1/3 of that of lead eluted from Sn37Pb solder, whereas the amount of silver eluted was less than 1/100 of that of lead. In contrast, the elution of tin from lead-free solders alloyed with much bismuth, which has a higher oxidation-reduction potential than tin, was more than that from Sn37Pb solder. The galvanic potential difference increased the elution of tin, lead and bismuth from solders joined to copper. Since eluted bismuth, silver and tin were easily changed to colloidal precipitate, it is considered that lead-free solder is unlikely to cause significant water pollution.
