相图计算在电子材料焊接中的应用

Application of CALPHAD in soldering of electronic materials

焊料与基体的界面反应对高性能电子材料焊接接头的力学性能和可靠性都有着很重要的影响。把焊接过程分为界面反应和剩余焊料凝固两个过程进行讨论 ,在相图热力学的基础上 ,通过计算亚稳相图、比较界面处局部平衡时各相形成驱动力大小 ,预测了Sn 3.5 %Ag/Cu、Sn 2 5 %Ag/Cu和Sn 3.5 %Ag/Ni扩散偶界面反应过程中的中间相形成序列 ;同时利用Scheil Gulliver凝固模型模拟了Sn 2 5 %Ag/Cu体系中过剩焊料的非平衡凝固过程 ,预测了焊料在随后冷却过程中的相演变信息。计算预测的结果与前人的实验结果吻合很好。

It is believed that reaction products in the interface between solder and substrate have great effects on mechanical properties and reliability of the solder/substrate joint. Based on the calculations of metastable phase equilibria between the solder and the substrate and the comparison of the driving forces of formation of individual intermetallic compounds, a thermodynamics method was used to predict the formation sequence of the intermetallic compounds during the interfacial reaction period. This method was applied to the interfacial reaction of Sn-3.5%Ag/Cu, Sn-25%Ag/Cu, and Sn-3.5%Ag/Ni solder/substrate systems. In addition, by using Scheil-Gulliver model, the non-equilibrium solidification of Sn-25%Ag/Cu system was modeled and the microstructure evolution was also predicted. The results from thermodynamic calculations are in good agreement with previously reported experiments.