Abstract
Sn-(Cu)/Cu 6 Sn 5 /Ni couples with indentation markers are examined at 210 °C. The original thickness of Cu 6 Sn 5 is 20 μm, and the Cu contents of the Sn-(Cu) solders are 0, 0.7 and 1.0 wt%. The Ni 3 Sn 4 phase is formed in all Sn-(Cu)/Cu 6 Sn 5 /Ni couples. In the Sn-0.7 wt%Cu/Cu 6 Sn 5 /Ni, Ni 3 Sn 4 is the dominant growing phase and the thickness of Cu 6 Sn 5 remains almost unchanged with reaction. Both Cu 6 Sn 5 and Ni 3 Sn 4 grow thicker with longer reaction time in the Sn-1.0 wt%Cu/Cu 6 Sn 5 /Ni couple, while the growth rate of the Cu 6 Sn 5 is much higher. In the Sn/Cu 6 Sn 5 /Ni couple, Ni 3 Sn 4 grows at the expense of the Cu 6 Sn 5 phase. Sn and Cu are more active diffusion species. The growth of Cu 6 Sn 5 phase is at the Cu 6 Sn 5 /Ni 3 Sn 4 interface, and that of the Ni 3 Sn 4 phase occurs at both the Cu 6 Sn 5 /Ni 3 Sn 4 and the Ni 3 Sn 4 /Ni interfaces. © 2008 Elsevier Ltd. All rights reserved.