Influence of indium on microstructure and creep properties of SnAg3.5InX (X=0,2,4,8) solder alloys

This work aims to investigate the influence of the element In content on the microstructure and creep properties of Sn-Ag-In solder alloys. For that, four different alloy compositions consisting of a base alloy SnAg3.5 and the addition of 0, 2, 4 and 8 wt% of indium were studied. Those alloys were tested concerning melting and recrystallization temperatures, creep resistance and microstructures. For the creep tests, bulk tensile specimens were used. The creep experiments were performed under different temperatures and stresses. The results were fitted according to the Sinh-Law. Microstructural investigation showed the refinement of microstructure and the formation of different intermetallic compounds in the presence of higher indium contents. Creep measurements have shown that there is a tendency of increasing creep resistance as the indium content is increased. The Sinh-Law describes the alloys creep behaviour properly and the influence of indium content on the constants Q, n, B and A was established. Activation energy for creep (Q) increases with indium content, while the stress exponent (n) decreases.