| 摘要 |
PROBLEM TO BE SOLVED: To prevent the environmental pollution by Pb in which Pb in wastes is eluded by acid rain to form sulfonic acid and to pollute ground water, and to increase the mechanical strength of a soldered part as a result of the alloying by providing a lead-free solder alloy containing Cu and Ni of the specified content, and the balance Sn-Cu-Ni alloy of Sn. SOLUTION: A lead-free solder alloy preferably has the composition consisting of, by weight, 0.05-2% Cu, 0.001-2% Ni, and the balance Sn. In this alloy, Ni is substituted for a part of the Cu-added composition in Sn-Cu alloy as a Pb-free solder alloy. When the ratio of Cu to Ni is appropriately selected by the soldering condition, the mechanical strength and the wettability are not inferior to those of the Sn-Cu alloy. The wettability is better than that of the Sn-Cu alloy by the combination of Cu with Ni. In the soldering, the melting point as low as possible is requested, but the melting point is hardly different from that of the Sn-Cu alloy. |
