工艺参数对Sn-0.3Ag-0.7Cu/Cu焊点界面组织和力学性能的影响

互连焊点界面反应形成的金属间化合物(IMC)对焊点服役可靠性会产生显著影响。研究了不同工艺参数(回流温度、回流时间和回流次数)条件下,Sn-0.3Ag-0.7Cu/Cu焊点界面金属间化合物的演变及对焊点力学性能的影响,同时对焊点断裂机制进行了分析。结果表明,随着回流温度和回流时间的增加,金属间化合物η-Cu6Sn5相的形貌由贝状向板条状转变,并可观察到η相溶入焊点内部。在265℃回流时,随着回流时间增加,贝状η相不断长大,晶粒数不断减少;界面IMC的生长符合幂指数生长规律,其生长指数为0.339。回流次数对焊点剪切强度的影响为先增后减,断裂模式从纯剪切断裂到微孔聚集型断裂再到局部脆断转变。

Effect of Processing Parameters on Interfacial Microstructure and Mechanical Property of Sn-0.3Ag-0.7Cu/Cu Solder Joint

The intermetallic compound (IMC) formed at the interface between solder and substrate has a significant effect on the reliability of interconnection solder. The evolution of interfacial IMC in Sn-0.3Ag-0.7Cu/Cu solder joint and its effect on the mechanical properties were investigated under the different processing parameters including reflowing temperature, reflowing number and reflowing time, meanwhile, the fracture mechanism was also evaluated. The results indicate that IMC (η-Cu6Sn5) morphology is transformed from scallop-shaped to lath-shaped with the increase of reflowing time and temperature, and η phase dissolved into the solder position can be observed. With increasing in the reflowing time at 265 ℃, the η phase is grown increasingly with the decrease of grains. The growth rate of the interfacial IMC follows index power rules and its growth exponent is 0.339. It is also shown that the influence of the reflowing number on the shear strength is first increased and then decreased, and fracture mechanism is changed from pure shear fracture to micro-pore gathering fracture and then to partial brittle failure.