Mechanical and microstructural characteristics of dilute SnBi and SnBiIn alloys

This paper presents extensive data on the mechanical properties of dilute SnBi alloys, where the Bi-content varies from 0.5 to 6 at%. The data are determined experimentally in the temperature range of -20 to +150/spl deg/C using numerous different strain rates. The effect of In addition on the behavior of the SnBi3% and SnBi6% alloys is also investigated. Since it is obvious that the amounts of different phases-and not only the Sn-rich solid solution-change significantly during temperature cycling, notably in the SnBiIn alloys, thermodynamic assessments of the systems are also performed. The analyses which enable to evaluate the volume fractions of the phases in the alloys of fixed nominal compositions as a function of temperature indicated that there are considerable differences in the stabilities of the equilibrium structures of the solder joints at the peak cycling temperatures.