锗的表面吸附作用对Sn2.5Ag0.7Cu/Cu界面及润湿性能的影响

分析了Sn2．5Ag0．7Cu／Cu钎料在添加活性元素前后，润湿性能及界面形貌的演变规律．测定了Ge元素含量不同时钎料的铺展面积，用扫描电镜对化合物的形态进行了分析．分析了钎焊时固液相界面张力与活性元素在该处吸附量的关系及其对润湿性能的影响．结果表明，在钎料中Ge元素质量分数为0．5％时，其在界面处的吸附量明显增加，化合物向前生长趋势强烈，润湿铺展面积最大．在质量分数为1．0％时其吸附量依然明显，但润湿效果减弱，且化合物的厚度相对变薄．这说明Ge元素在一定的范围内会降低钎焊界面处的张力，并且当偏聚量较大时可抑制铜和钎料之间的扩散作用，阻碍化合物生长．

Effects of surface absorption of Ge on Sn2.5Ag0.7Cu/Cu interfacial reaction and wettability

The evolution of wetting property and interfacial morphology of Sn2.5Ag0.7Cu solder was investigated before and after adding active elements.The spreading areas of solder with different contents of Ge were measured,and the morphology of the compound was analyzed with SEM.The relationship between tension on the solid-liquid interface and the absorption amount of active elements on the same place during soldering and its effect on wetting properties were studied.The results showed that when the Ge content in solder was 0.5%,its absorption on the interface quickly raised,the forward-growing tendency of the compound was strong,and the spreading area was the largest.When the Ge content in solder was 1.0%,the absorption remained obvious but the wetting performance was weakened,and the thickness of the compound was relatively thinner.This phenomenon indicates that Ge can reduce the tension on the soldering interface within a certain range.In addition,when the absorption was relatively large,the diffusion between Cu and solder can be restrained and the growth of the compound can be hindered.