Solid-state interfacial reaction of Sn-Ag solders with polycrystalline Cu and (0 0 1) Cu substrate

Abstract

• For sn-Ag solder, the growth of Cu 3 Sn on (0 0 1)Cu is faster than on polycrystalline Cu in aging. • Ag increases the difference in Cu 3 Sn thickness on (0 0 1)Cu and polycrystalline Cu in aging. • Ag is beneficial to maintain the preferred orientation of Cu 6 Sn 5 in aging. The growth of Cu 3 Sn is associated with the formation of Kirkendall voids and is important to the reliability of solder joints. In this paper, the effect of Ag on the growth behavior of Cu 3 Sn on (0 0 1) Cu and polycrystalline Cu during aging was compared. Besides, the orientation evolution of Cu 6 Sn 5 on (0 0 1) Cu during aging was also investigated. Results suggested the growth rate of Cu 3 Sn on (0 0 1) Cu is higher than that of polycrystalline Cu during solid-state aging and the difference in the Cu 3 Sn layer thickness increases with the increases of Ag content in the solder. Moreover, the addition of Ag is beneficial to maintaining the preferred orientation of Cu 6 Sn 5 on (0 0 1) Cu during solid-state aging. The results have great help to deepen the understanding of the difference in growth behavior of intermetallic compounds on (0 0 1) Cu and polycrystalline Cu during aging.