Microstructural stability and mechanical properties of Sn-1Ag-0.5Cu solder alloy with 0.1 wt.% Al addition under high-temperature annealing

Abstract

Effects of 0.1 wt.% Al addition on the microstructural stability and mechanical properties of the low-Ag-content Sn-1Ag-0.5Cu (SAC105) solder alloy under high-temperature aging were investigated. Addition of Al suppresses the formation of Cu 6 Sn 5 intermetallic compound (IMC) particles and leads to the formation of large AlCu IMCs. Moreover, the Ag 3 Sn IMC particles become larger and less-packed in the interdendritic regions after the additions of Al. The addition of Al also leads to enlarge the primary β-Sn dendrites and diminish the interdendritic regions. The tensile test results indicate that the addition of Al significantly decreases the elastic modulus, yield strength, and total elongation. After 720 h and 24 h of aging at 100°C and 180°C, respectively, the Al-bearing SAC105 solder alloy exhibits more resistance to microstructural coarsening than the SAC105 solder alloy which in turn significantly reduces the mechanical properties degradation with aging.