Fe粉对Sn-3Ag-0.5Cu复合钎料组织及性能的影响

通过在钎料中添加Fe粉颗粒,研究其对Sn-3Ag-0.5Cu复合无铅钎料的黏度、熔点、钎焊接头界面微观组织、与Cu基板之间的润湿性及焊点力学性能的影响。结果表明:微米级Fe粉的添加增加了复合钎料焊膏单位体积内焊粉的接触面积,使得焊膏内摩擦力增大,导致复合钎料焊膏的黏度增加;微米级Fe粉的添加对Sn-3Ag-0.5Cu钎料的熔化特性没有显著影响;钎焊时,由于重力偏聚及界面吸附作用,Fe粉颗粒集中沉积于Sn-3Ag-0.5Cu-Fe/Cu钎焊接头界面处靠近钎料一侧,由于增大液态钎料黏度而导致钎料与Cu板间的润湿性降低;与Sn-3Ag-0.5Cu/Cu相比,Sn-3Ag-0.5Cu-Fe/Cu界面处钎料一侧粗大的β-Sn枝晶区消失,取而代之的是细小的等轴晶。Sn-3Ag-0.5Cu-1%Fe/Cu的剪切强度为46 MPa,比Sn-3Ag-0.5Cu/Cu剪切强度提高39%;靠近界面金属间化合物处钎料基体的显微硬度提高约25%。

Effect of Fe particles on microstructures and properties of Sn-3Ag-0.5Cu lead-free solder

The effects of Fe particles on the viscosity,melting point,microstructure,wettability and mechanical properties of Sn-3Ag-0.5Cu solder paste were investigated.The results show that the addition of Fe particles with micro size increases the contact area between the solder balls and friction force of solder pastes,which is due to the increasing viscosity of solder paste.The density of Fe is higher than that of the Sn-3Ag-0.5Cu,and Fe particles are adsorbed to the interface to increase the viscosity of liquid solder,so,the wettability of solder alloys are degraded.Compared with the Sn-3Ag-0.5Cu/Cu,the fine equiax crystal in Sn-3Ag-0.5Cu-Fe/Cu is found instead of the bulky β-Sn arborescent crystal.The shear strength of the Sn-3Ag-0.5Cu-1%Fe/Cu is 46 MPa,which is 39% higher than that of the Sn-3Ag-0.5Cu/Cu.The microhardness of the matrix increases approximately 25% as a result of incorporation of Fe particles.