Influence of Ag-modified graphene nanosheets addition into Sn-Ag-Cu solders on the formation and growth of intermetallic compound layers

In this study, varying amounts of Ag-modified graphene nanosheets (Ag-GNSs) were added to Sn-Ag-Cu (SAC) solders to synthesize composite solders. Then, the morphology and thickness of the intermetallic compound (IMC) layers were investigated during the liquid solid reactions and isothermal aging. The test results revealed that the IMCs were scallop-shaped after soldering, but they changed from scallop shaped to an irregular shape with increasing aging time. The IMC thickness and diffusion coefficients of the composite solders were both found to be lower than those of the plain solders. Moreover, it is worth noting that with the same amount of reinforcement, the composite solders reinforced with Ag-GNSs exhibited thinner IMC layers and lower diffusion coefficients than the solders reinforced with GNSs alone. Furthermore, Ag-GNSs prepared using ball milling yielded thinner IMC layers and lower diffusion coefficients than the same amount of Ag-GNSs prepared via mechanical mixing using a blender. Our results indicate that Ag-GNSs are more influential on delaying the growth of IMC layers than GNSs alone and that ball milling has advantages over mechanical mixing using a blender for the preparation of Ag-GNS composite solders. (C) 2017 Elsevier B.V. All rights reserved.