Indentation creep of lead-free Sn-Bi solder alloys as replacements of Sn-Pb used in microelectronic packaging

Creep behavior of three lead-free Sn-Bi alloys with 1-5 wt.% Bi, together with the Sn-37%Pb solder alloy as the material for comparison, was studied by Vickers indentation testing at room temperature. The stress exponents in the range 13-16, determined through different indentation methods, are in good agreement. The measured exponents imply that dislocation movement is the possible mechanism during room-temperature creep deformation of these solders alloys. All three tin-based alloys showed creep resistances higher than that of the Sn-37%Pb alloy. Creep resistance increased by increasing Bi content of the alloys.