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

Disclosed is a lead-free solder alloy excellent in impact resistance and vibration resistance. Also disclosed are a solder ball using such a lead-free solder alloy, and an electronic member having a solder bump using such a lead-free solder alloy. Specifically disclosed is a lead-free solder alloy characterized by consisting of 1.0-2.0% by mass of Ag, 0.3-1.0% by mass of Cu, 0.005-0.10% by mass of Co, 0.0001-0.005% by mass of Fe and the balance of Sn and unavoidable impurities. By containing Co and Fe, a Cu atom site in a Cu<SUB>6</SUB>Sn<SUB>5</SUB> intermetallic compound layer formed at the interface with the electrode is substituted with an atomic species having a smaller atomic radius than Cu, thereby reducing strain in the Cu<SUB>6</SUB>Sn<SUB>5</SUB> intermetallic compound layer. Consequently, there can be prevented occurrence of a fracture at the interface between a Cu<SUB>3</SUB>Sn intermetallic compound layer and the Cu<SUB>6</SUB>Sn<SUB>5</SUB> intermetallic compound layer.