| 摘要 |
PROBLEM TO BE SOLVED: To provide a solder alloy with excellent soldability and good machining properties, the Pb content of which is kept to be 1 atom% or less. SOLUTION: The solder alloy is mainly composed of Sn and contains 0.05-15 atom% Ag, 0.05-20 atom% Cu, 0.01-10 atom% Al, and less than 1 atom% Pb. Therefore, the temperature of melting start is set suitable for soldering at the extent of 220-350 deg.C, and excellent soldability is obtained for the members to be jointed of electric devices such as a Cu base metallic layer and the like. Furthermore, due to excellent mechanical properties, and particularly excellent tensile strength compared with a conventional non-lead solder, the solder alloy is good in shock resistance and heat cycle fatigue resistance and performs an adequate function to substitute for existing Pb-Sn base solder alloy. The considerable reason is that the Al-Cu base phase is dispersed in a matrix while being fine grains at the extent of 3-20μm.
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