Abstract: The mechanical behaviors and failure mechanism of lead-free Sn-3.0Ag-0.5Cu micro-scale solder joints with a constant diameter of 400 μm and a height range of 125~325 μm during quasi-static tensile and shear state were investigated at 100℃ and 25℃ with accurate dynamic mechanical analyzer DMA Q800.The experimental results show that the tensile and shear strength of all micro-scale solder joints decreased with the increasing of the joint height.However,under the same loading rate of 1N/min at 100℃,the shear strength of solder joints was lower than the tensile strength,and the shear fracture strain was also lower than the tensile one,revealing that the shear loading was severer for micro-interconnection solder joints in electronic packaging.Nevertheless,under the same loading rate,the tensile strength and strain of micro-scale solder joints with the same size decreased with the increasing of service temperature.