Effects of Ag Content on the Mechanical Properties of Bi-Ag Alloys Substitutable for Pb based Solder

As one of the candidate materials for the high-temperature-resistant joining materials which substitute from the conventional Pb-rich solder, Bi-Ag solder alloys were used to investigate the characteristics. The mechanical properties have been investigated on lead-free Bi-Ag alloys using tensile tests to clarify the important characteristics for solder alloys having reflow resistant relatively high melting temperature solders. The tensile strength gradually increased with increase of Ag content, however, the elongation showed a minimum at eutectic Bi-2.5Ag and it only slightly increased with increase of Ag content up to 11%Ag for quenched alloys. On the other hand, air cooled Bi-11Ag alloy showed improved elongation about 20%, the value is much higher than that of quenched one, about 3%. The hypereutectic Bi-11Ag solder can be used as a solder material having relatively good wettability and mechanical properties, in particular it showed elongation of 20% under air cooled condition.