Effect of Ni and Ni-coated Carbon Nanotubes on the interfacial reaction and growth behavior of Sn58Bi/Cu intermetallic compound layers

Abstract

The interface reactions between Cu and Sn58Bi solder doped with mass fraction of 0.5 % Ni, 1 % Ni, 0.5 % Ni-CNTs and 1 % Ni-CNTs after reflow and solid-state aging were studied. Results show that the Ni and Ni-CNTs restrain the growth of IMC layer during reflow. After 120 and 240 h aging at 100 °C, the growth of total IMC layer and Cu3Sn layer was inhibited by the addition of Ni and Ni-CNTs. During aging, the thickness of (Cu, Ni)6Sn5 layer in Ni-CNTs-doped solder joint is always thinner than that in Ni-doped solder joint because the Ni-CNTs reduce the CTE of SnBi solder more effectively. The reason for the growth of Cu3Sn with Ni doped less than that with Ni-CNTs is that the stability of (Cu, Ni)6Sn5 gets an improvement as the Ni content increases. Besides, the IMC growth rate of composite solder joints decreases with the increasing Ni and Ni-CNTs content.