Sn-Ag-Cu和Sn-Ag-Bi焊料在Ni-P基板上焊点剪切强度的分析

Analysis about Shear Strength of Sn-Ag-Cu and Sn-Ag-Bi Solder on Ni-P Board

采用改进的剪切强度测试方法，对Sn-Ag-Cu，Sn-Ag-Bi无铅焊料在Ni-P基板上的焊点，经0～1000h热时效后的剪切强度进行了测量，并对断裂面的微观结构进行了观察分析．结果表明焊点的剪切断裂位置与焊接界面金属间化合物（intemetallic compound，IMc）的厚度有关，随着IMC的增厚，前切断列的位置将逐渐接近于IMC与基板的界面；Sn-Ag-Bi焊点的剪切强度明显高于Sn-Ag-Cu，剪切断裂则更易于发生在IMC层中。

The shear sthrength of Sn-Ag-Cu and Sn-Ag-Bi lead-free solder joints on Ni-P board are tested after aging up to 1 000 h by an improved shear test method. Moreover, the microstructures of the facture surface are studied. The results indicate that the shear strength of solder joint and fracture location are related to the morphology and composition of the intermetallic compound（IMC）. With the increase of IMC thickness, the fracture location approaches gradually to the interface between IMC and the board. The shear strength, of Sn-Ag-Bi solder joint is much higher than that of Sn-Ag-Cu, while the fracture failure in brittle IMC layer is more easily to occur for Sn-Ag-Bi solder joint.