Tin-base solder alloys with and without Pb are widely
used to interconnect electronic devices and Cu-base conductor
alloys in electronic industry. However, binary Cu–Sn intermetallic
compounds are formed at the interface between
the solder and conductor alloys during soldering and then
continuously growdue to heating by energization under usual
service conditions [1–9]. These compounds are very brittle
and possess high electrical resistivities. Thus, the growth of
such intermetallic compounds gradually deteriorates the electrical
and mechanical properties of the interconnection.