Microstructure and mechanical behavior of Graphene NanoSheets enhanced lead-free Sn–0.3Ag–0.7Cu solder

The utilization of Sn–Ag–Cu (SAC) lead-free composite solders as substitutes for traditional Sn–Pb solders has been a subject of interest. This research article focuses on the Graphene NanoSheets (GNSs) dopant into low silver SAC0307 solder to study the impact of GNSs concentration (ranging from 0 to 0.2 wt%) on the microstructural and mechanical properties of soldered joints. The orientation relations demonstrate a notable increment in the number of gains and a significant decrease in the grain size of Sn by adding 0.1 wt% GNSs, attributed promoting heterogeneous Sn grain nucleation. Furthermore, the addition of 0.1 wt% GNSs led to an increase in the dislocation density of SAC0307 from 5.4 × 10¹⁴ to 1.15 × 10¹⁵ m⁻². The mechanical properties of composite solder, hardness (~ 16%), and joint shear strength (~ 23%), were improved when compared to the non-composite SAC0307 solder. Moreover, during the nanoindentation creep test, the solder containing 0.1 wt% GNSs exhibited the lowest penetration depth and highest creep resistance. In addition, the melting point of composite solders did not change significantly with the addition of GNSs dopant. This research features the potential benefits of incorporating GNSs into SAC solder compositions, highlighting improvements in mechanical properties and microstructural characteristics up to an optimal GNSs concentration of 0.1 wt%.