热迁移作用下Cu_6Sn_5的组织演变及生长动力学研究

Microstructural Evolution and Growth Kinetic of Cu_6Sn_5 under Thermomigration

以Cu/Sn-0.7Cu/Cu焊点为研究对象,观察其在热迁移作用下界面金属间化合物随时间的演变规律,研究界面IMC的生长,得出生长动力学参数。结果表明,在热迁移作用下,焊点两端IMC呈现非对称性生长,热端减薄而冷端增厚,冷端在增厚的过程中会在IMC内形成空洞。IMC的生长是浓度梯度和热迁移共同作用的结果,在冷端二者效果叠加,在热端二者效果相反。由Cu_6Sn_5厚度随时间变化曲线得到生长动力学时间指数,冷端为0.55,热端为-0.16。Cu原子在冷端的迁移通量为1.37×10^(-7)mol/(m^2·s)。

The Cu/Sn-0.7Cu/Cu solder joint was used as the initial sample to observe the evolution of interfacial IMCs with time under thermomigration.The growth of IMCs was observed and its dynamic parameters were presented.The results show that asymmetrical growth is present at the IMCs in two ends of the solder joint under thermomigration.The hot end is thinned and the cold end is thickened.The cold end forms holes in IMCs during thickening process.The growth of IMCs is the co-action of concentration gradient and thermomigration,which are concentrated to the growth of IMCs in the cold end and opposite effects in the hot end.Time index of growth kinetic is obtained by the thickness curve of Cu6Sn5,which is 0.55in cold end and-0.16in hot end.Finally,the migration flux of Cu atoms is calculated as1.37×10^-7mol/（m^2·s）.