| 摘要 |
PROBLEM TO BE SOLVED: To obtain a solder alloy having low melting point without deteriorating the mechanical property by keeping a prescribed content ratio of Bi and In in an Sn-Ag base solder alloy containing Bi and In of specified quantities. SOLUTION: This Sn-Ag base solder alloy contains, by wt.% 3-4% Ag, 5-10% In and 2-6% Bi and the balance Sn, and <12% In+Bi and Bi<=In. This solder alloy has low melting point, such as <=210 deg.C, and has excellent mechanical characteristics, including tensile strength and elongation, and does not contain the harmful elements such as Pb or Cd. Since this solder alloy does not have an eutectic peak at low temperature, the heat fatigue characteristics is improved. Then Ag content is 3.5% in the most suitable state, actually 3-4%, based on the producing yield of the solder alloy. The In content is preferably 6 to 10%.
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