Effect of Graphene Nanoplatelets on Wetting, Microstructure, and Tensile Characteristics of Sn-3.0Ag-0.5Cu (SAC) Alloy

The effect of graphene nanoplatelets (GNPs) on the wettability, microstructure, and tensile properties of Sn-3.0Ag-0.5Cu (SAC 305) was studied using melting and casting route. The microstructure of the bulk solder is observed with a scanning electron microscope and transmission electron microscope, and the intermetallic compound (IMC) phases are identified by electron probe micro-analyzer. The solderability of the samples is assessed by spreading and wetting tests on a Cu substrate. The experimental results indicate that an addition of 0.05 wt pct GNPs in Sn-3Ag-0.5Cu solder improves the spreading and wettability significantly compared to monolithic SAC. It is also revealed that the thickness of the Ag3Sn IMCs is reduced as compared to the monolithic SAC alloy. Tensile results show that the composite solder exhibits the 13.9 pct elongation and 17 pct increase in the ultimate tensile strength when 0.05 wt pct GNPs in Sn-3Ag-0.5Cu alloy are added. This may be due to the refinement of the IMCs in composite solders compared to the same in Sn-3Ag-0.5Cu alloy brought about by the uniform dispersion of graphene nanoplatelets. It is suggested in this study that the amount of GNPs in Sn-3Ag-0.5Cu alloy should not exceed 0.05 wt pct as it may degrade the desired properties due to the agglomeration of GNPs. (C) The Minerals, Metals & Materials Society and ASM International 2015