无铅焊点拉伸性能的影响
(华南理工大学 机械与汽车工程学院，广州 510640)
摘 要: 采用扫描电子显微镜(SEM)、能谱仪(EDS)和微拉伸实验，研究Cu/Sn-3.0Ag-0.5Cu/Cu对接焊点在不同电迁移时间下阳极、阴极界面金属间化合物(IMC)的生长演变规律及焊点抗拉强度的变化，同时对互连焊点的断口形貌及断裂模式进行分析。结果表明：在电流密度(J)为1.78×104 A/cm2、温度为373 K的加载条件下，随着加载时间的延长，焊点界面IMC的生长呈现明显的极性效应，阳极界面IMC增厚，阴极界面IMC减薄，且阳极界面IMC的生长符合抛物线规律；同时，互连焊点的抗拉强度不断下降，焊点的断裂模式由塑性断裂逐渐向脆性断裂转变，断裂位置由焊点中心向阴极界面处转移。
关键字: 界面化合物；电迁移；极性效应；抗拉强度；断裂
tensile properties of Sn-3.0Ag-0.5Cu lead-free solder joint
（School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640，China）
Abstract:The butting solder joint of Cu/Sn-3.0Ag-0.5Cu/Cu was used to investigate the evolution of the intermetallic compound (IMC) at the anode and cathode interface, and the degradation of the tensile strength of solder joint with different electric current stressing times, by a scanning electron microscope equipped with energy dispersive spectrometer and micromechanical test. Meanwhile, the fracture of solder joint was also evaluated. The results show that under the condition of J=1.78×104 A/cm2 and T=373 K, with increasing the current stressing time, the growth of interfacial IMC presents an obviously polarity effect, the IMC thickens at the anode surface and thins at the cathode surface, and the growth of the interfacial IMC at anode follows a parabolic growth rule. The ultimate tensile strength of the solder joint declines continuously. The fracture mode gradually transforms from plastic fracture to brittle fracture, and the fracture position transfers from the middle to the cathode interface of solder joint.
Key words: intermetallic compound; electromigration; polarity effect; tensile strength; fracture
