Lead-free solder alloy, solder ball and electronic member, and lead-free solder alloy, solder ball and electronic member for automobile-mounted electronic member

摘要

A lead-free solder alloy exhibiting good performance in impact resistance and vibration resistance. Also provided are a solder ball using such a lead-free solder alloy, and an electronic member having a solder bump using such a lead-free alloy. Specifically, the lead-free solder alloy consists of 1.0 to 2.0% by mass of Ag, 0.3 to 1.0% by mass of Cu, 0.005 to 0.1% by mass of Ni and the balance including Sn and unavoidable impurities. In an Sn—Ag—Cu based solder joint portion on a Cu electrode, a Cu₃Sn intermetallic compound layer is formed directly on the Cu electrode, and then a Cu₆Sn₅ intermetallic compound layer is formed thereon. A Cu atomic site in the Cu₆Sn₅ intermetallic compound layer is replaced by Ni having a smaller atomic radius than Cu to thereby reduce strain in the Cu₆Sn₅ intermetallic compound layer, thus enabling impact resistance and vibration resistance to be improved therein.