Inherent growth habit of Cu6Sn5 phase at the liquid Sn0.7wt%Cu solder/(111)Cu joint interface

Morphologies and growth habits of Cu6Sn5 formed at the liquid Sn0.7wt%Cu solder and (111)(Cu) single crystal joint interface were investigated in this study. The steady-state grain growth of Cu6Sn5 nanorods were observed in the internal liquid solder. Furthermore, the formations of the roof-type morphology of interfacial Cu6Sn5 phase were not only dependent upon the low lattice mismatch directions of Cu atoms between Cu6Sn5 and (111)(Cu), but also controlled by the inherent nanorods growth habit which was confirmed by our theoretical and experimental study. In addition, the side facets of Cu6Sn5 phase on the solder side were also analyzed. From the results, the {10 (1) over bar0} facets of the rod-type morphology is caused by the thermodynamic reason, while the {11 (2) over bar0} facets of the roof-type morphology is due to the kinetic reason.