A solder alloy comprises Sn, Ag, Cu, and Mn and has a melting temperature of about 211 degrees C. A solder joint and solder process embody the solder alloy as well as solder balls and solder paste made therefrom to provide a solidified joint that includes three different intermetallic phases and a Sn metal phase. An exemplary Sn—Ag—Cu—Mn alloy consists essentially of about 3 to about 4 weight % Ag, about 0.80 to about 1.0 weight % Cu, and about 0.05 to about 0.15 weight % Mn, and balance consisting essentially of Sn.
US 2010/0203353 A1
Iowa State University Research Foundation, Inc.
Anderson, Iver E.; Harringa, Joel; and Walleser, Jason K., "Pb-Free Sn-Ag-Cu-Mn Solder" (2010). Iowa State University Patents. 80.