This research sought to improve the properties of SAC305 solder joints by the addition of 1 and 2 wt.%Bi.The effects of bismuth doping on the microstructure,thermal properties,and mechanical performance of the SAC305−...This research sought to improve the properties of SAC305 solder joints by the addition of 1 and 2 wt.%Bi.The effects of bismuth doping on the microstructure,thermal properties,and mechanical performance of the SAC305−xBiCu solder joints were investigated.Bi-doping modified the microstructure of the solder joints by refining the primaryβ-Sn and eutectic phases.Bi-doping below 2 wt.%dissolved in theβ-Sn matrix and formed a solid solution,whereas Bi additions equal to or greater than 2 wt.%formed Bi precipitates in theβ-Sn matrix.Solid solution strengthening and precipitation strengthening mechanisms in theβ-Sn matrix increased the ultimate tensile strength and microhardness of the alloy from 35.7 MPa and 12.6 HV to 55.3 MPa and 20.8 HV,respectively,but elongation decreased from 24.6%to 16.1%.The fracture surface of a solder joint containing 2 wt.%Bi was typical of a brittle failure rather than a ductile failure.The interfacial layer of all solder joints comprised two parallel IMC layers:a layer of Cu6Sn5 and a layer of Cu3Sn.The interfacial layer was thinner and the shear strength was greater in SAC305−xBiCu joints than in SAC305Cu solder joints.Therefore,small addition of Bi refined microstructure,reduced melting temperature and improved the mechanical performance of SAC305Cu solder joints.展开更多
Diamond/SnAgCu composite solder bumps were prepared on Cu pad by mechanically incorporating diamond particles into Sn3.0Ag0.5Cu （SAC） solder powders, mixing with flux and reflowing at 260℃ for 60 s. The spreading a...Diamond/SnAgCu composite solder bumps were prepared on Cu pad by mechanically incorporating diamond particles into Sn3.0Ag0.5Cu （SAC） solder powders, mixing with flux and reflowing at 260℃ for 60 s. The spreading areas of composite solder were calculated and the distributions of copper-coated diamonds were characterized. When diamond additions were below 3 wt%, the spreading area decreased with diamond additions, and the diamonds distributed mainly at the interface between solder and Cu pad; however, when additions were beyond 4 wt%, the discharge of diamond particle occurred, and the spreading area increased due to the reduction of surface energy.展开更多
文摘This research sought to improve the properties of SAC305 solder joints by the addition of 1 and 2 wt.%Bi.The effects of bismuth doping on the microstructure,thermal properties,and mechanical performance of the SAC305−xBiCu solder joints were investigated.Bi-doping modified the microstructure of the solder joints by refining the primaryβ-Sn and eutectic phases.Bi-doping below 2 wt.%dissolved in theβ-Sn matrix and formed a solid solution,whereas Bi additions equal to or greater than 2 wt.%formed Bi precipitates in theβ-Sn matrix.Solid solution strengthening and precipitation strengthening mechanisms in theβ-Sn matrix increased the ultimate tensile strength and microhardness of the alloy from 35.7 MPa and 12.6 HV to 55.3 MPa and 20.8 HV,respectively,but elongation decreased from 24.6%to 16.1%.The fracture surface of a solder joint containing 2 wt.%Bi was typical of a brittle failure rather than a ductile failure.The interfacial layer of all solder joints comprised two parallel IMC layers:a layer of Cu6Sn5 and a layer of Cu3Sn.The interfacial layer was thinner and the shear strength was greater in SAC305−xBiCu joints than in SAC305Cu solder joints.Therefore,small addition of Bi refined microstructure,reduced melting temperature and improved the mechanical performance of SAC305Cu solder joints.
基金supported by the Scientific and Technological Development Projects in Shandong Province under Grant No.2010GGX10307
文摘Diamond/SnAgCu composite solder bumps were prepared on Cu pad by mechanically incorporating diamond particles into Sn3.0Ag0.5Cu （SAC） solder powders, mixing with flux and reflowing at 260℃ for 60 s. The spreading areas of composite solder were calculated and the distributions of copper-coated diamonds were characterized. When diamond additions were below 3 wt%, the spreading area decreased with diamond additions, and the diamonds distributed mainly at the interface between solder and Cu pad; however, when additions were beyond 4 wt%, the discharge of diamond particle occurred, and the spreading area increased due to the reduction of surface energy.
