Effect of Sb Additions on the Creep Behaviour of Bi Containing SAC Alloys

Abstract

Creep behaviour as well as microstructural evolution resulting from long-term isothermal treatment of cast Sn-3Ag-3Bi-0.5Cu-(0.6–5)Sb solder alloys for electronic packaging applications are investigated. Mechanisms of deformation are evaluated via creep tests conducted at a temperature range of 25–150°C using 7.5–12.5 MPa stress and in-depth scanning electron microscopy analysis. Short primary creep stages (< 1 h), an indication of low work hardening, followed by the secondary creep stage occurred in all conditions. Dislocation processes were found to control creep deformation above 100°C. Increase in Sb content has negligible effect on minimum creep rates but does affect the duration of secondary creep stage. A change in activation energy of creep deformation is determined at temperatures below 100°C.