Lead-free “copper wire/Sn-3.0Ag-0.5Cu (SAC305) solder/copper wire” sandwich-structured micro-scale solder joints with a constant diameter (d = 400 μm) and various heights (125, 225, and 325 μm) were adopted to carried out the mechanical behavior research. Experimentally, quasi-static shear and tensile experiments were conducted by using a precision dynamic mechanics analyzer (DMA Q800). Then, the micro-scale solder joint model was built to simulate shear and tensile behavior of solder joints using the finite element analysis software ABAQUS. The experimental results show that, when the solder joint diameter is fixed, the smaller the joint height is, the stronger the shear strength and tensile strength. Under the same test conditions (225 μm), the shear strength of micro-scale solder joints of the same size is lower than the tensile strength, which indicates that the service environment of electronic packaging interconnection solder joints under shear stress is more severe. In addition, the micro-scale solder joints fracture at the interface of the solder joint and copper wire under shear force, but in the middle of the solder joint under tensile force. Different fracture failure mechanisms are found by observing the cross sections under different stress states.

无铅“铜线/的Sn-3.0Ag-0.5Cu的（SAC305）焊料/铜导线”夹心结构的微观尺度的焊点具有恒定直径（d = 400μm）和各种高度（125、225和325μm）进行了力学性能研究。实验上，使用精密动态力学分析仪（DMA Q800）进行了准静态剪切和拉伸实验。然后，使用有限元分析软件ABAQUS建立了微型焊点模型，以模拟焊点的剪切和拉伸行为。实验结果表明，当焊点直径固定时，焊点高度越小，剪切强度和拉伸强度越强。在相同的测试条件下（225μm），相同尺寸的微型焊点的剪切强度低于抗拉强度，这表明电子包装互连焊点在剪切应力下的使用环境更加恶劣。此外，微型焊点在剪切力作用下在焊点与铜线的界面处断裂，但在拉伸力作用下在焊点中间。通过观察不同应力状态下的横截面，可以发现不同的断裂破坏机理。