Effects of aging on Sn-1Ag-0.5Cu solder alloys containing 0.1Â wt.% and 0.5Â wt.% Al

In this paper, we investigate the effects of high-aging temperature and small additions (0.1 and 0.5 wt.%) of Al on the microstructure and mechanical properties of a Sn-1Ag-0.5Cu solder alloy. The results show that Al acts as both a softening and strengthening element for the Sn-1Ag-0.5Cu solder alloy depending on the amount added. The addition of 0.1 wt.% Al reduces the degradation of the mechanical properties associated with aging. This is because 0.1 wt.% Al-modified Sn-1Ag-0.5Cu solder exhibits a greater resistance to the coarsening of the intermetallic compounds formed during solidification compared to the unmodified Sn-1Ag-0.5Cu solder alloy. Conversely, the addition of 0.5 wt.% Al does not enhance the aging resistance. Additionally, like the microstructure of the unmodified Sn-1Ag-0.5Cu solder, the microstructure of the 0.5 wt.% Al-modified Sn-1Ag-0.5Cu solder becomes notably coarsened after aging.