SnAgCu-xTi在单晶硅表面的润湿行为

采用改良座滴法在高真空条件下研究了熔融Sn0.3Ag0.7Cu(SAC)-xTi(x为质量分数，%)在800 ~ 900 ℃与单晶硅表面的润湿行为. 结果表明，SAC-xTi/Si体系属于惰性润湿体系，钛的添加显著改善了润湿性. 在不添加钛时，SAC钎料在800 ℃与单晶硅润湿1 800 s后达到平衡，平衡接触角为63°；SAC-1Ti钎料在900 ℃润湿1 800 s后获得最小平衡接触角41°；SAC-3Ti钎料在900 ℃时达到平衡润湿的时间最短，仅为50 s，平衡接触角为48°. 润湿机制为钛加速了单晶硅表面氧化膜的去除. 在熔融钎料的铺展过程中，通过溶解?再析出机制和微掩膜机制，在固/液界面处形成了温度依赖的“金字塔”结构，温度越高，“金字塔”结构越稀疏且形貌越大. “金字塔”结构的出现并未改善体系的润湿性，由于其对三相线的钉扎作用，进而使得体系的润湿性变差.

Wetting behavior of monocrystalline Si by SnAgCu-xTi alloys

The wetting behavior of molten Sn0.3Ag0.7Cu (SAC)-xTi (x=wt.%) on the surface of monocrystalline Si at 800?900 ℃ was studied under high vacuum by the modified drop method. The results show that SAC-xTi/Si system belongs to the inert wetting system, and the Ti addition improved wettability, significantly. Without Ti addition, the system achieved the equilibrium?contact angle of 63° after 1 800 s at 800 °C; With 1% Ti addition, the system achieved the lowest equilibrium?contact angle of 41° after 1 800 s at 900 °C; With 3% Ti addition, the system achieved the fastest spreading in 50 s at 900 °C. The wetting mechanism is that the active component Ti accelerates the removal of oxide film on the surface of monocrystalline Si. During the spreading process of the molten solder, the temperature-dependent “pyramid” microstructure was formed at the solid/liquid interface through dissolution-reprecipitation mechanism and micro-mask mechanism, i.e., the higher temperature induced the sparse and larger “pyramid” microstructures. The appearance of “pyramid” microstructures did not improve the wettability of the system, on the contrary, the wettability became worse due to the pinning of the triple line.