Effects of heat treatment on mechanical, electrical properties and curtailment of electromigration in Sn-Ag-3.0-Cu-0.5 soldering based alloys

Sn-Ag-3.0-Cu-0.5 samples were initially prepared by melt mixing in induction furnace which were also re-melted and re-solidified. Afterwards, four Sn-Ag-3.0-Cu-0.5 specimens were additionally heat treated at 40, 60, 80 and 100 degrees C respectively for limited time span of 6 h. The Sn-Ag-3.0-Cu-0.5 specimens revealed 1.03, 1.10, 1.15 and 1.13 times improvement in hardness values relative to untreated or reference specimen. Similarly, ultimate tensile strength exhibited 1.08, 1.18, 1.25 and 1.21 correspondingly when compared with reference specimen. X-ray diffraction pattern further justified Sn-Ag-3.0-Cu-0.5 alloy and negated appearance of any new phase after heat treatment. Average crystallite sizes were also reduced to 1.06, 1.10, 1.42 and 1.09 folds after heat treatment at 40, 60, 80 and 100 degrees C for 6 h. Similarly, both phases (beta-Sn and intermetallic compounds) also evidenced decrement in their crystallite sizes in comparison to reference specimen. Moreover, resistivity also depicted increase of 1.13, 1.24, 1.32 and 1.25 times accordingly. Hence, our results show that the SAC-305 samples treated at 80 degrees C for 6 h may prove effective in countering electromigration problems by minimizing tensile strain gradients as well as current densities. Hence the SAC-305 specimen treated at 80 degrees C for 6 h may be recommended as potential candidate in solder applications.