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 exhibiting good performance 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, 0.005-0.1% by mass of Ni and the balance of Sn and unavoidable impurities. In an Sn-Ag-Cu solder joint portion on a Cu electrode, a Cu<SUB>3</SUB>Sn intermetallic compound layer is formed directly on the Cu electrode and a Cu<SUB>6</SUB>Sn<SUB>5</SUB> intermetallic compound layer is formed thereon. By substituting a Cu atom site in the Cu<SUB>6</SUB>Sn<SUB>5</SUB> intermetallic compound layer with Ni having a smaller atomic radius than Cu, strain in the Cu<SUB>6</SUB>Sn<SUB>5</SUB> intermetallic compound layer can be reduced, thereby improving impact resistance and vibration resistance in the solder joint portion.