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.
CONTRACTUAL ORIGIN OF THE INVENTION
 This invention was made with government support under Contract No. DE-ACO2-07CH11358 awarded by the U.S. Department of Energy. The government has certain rights in the invention.