Interfacial evolution of pure Sn solder bearing silicon carbide nanowires under isothermal aging and thermal cycling

Abstract

In this paper, the intermetallic compound (IMC) growth behaviors of Sn/Cu and Sn–0.6SiC/Cu solder under isothermal aging (50, 100, 150, 200 and 250 h) and thermal cycling (300, 600, 900, 1200 and 1500 cycles) were studied. The results manifested that the IMC layer got thicker in Sn/Cu solder and Sn–0.6SiC/Cu solder as the aging time or thermal cycles increased, but the IMC thickness of Sn solder incorporated with silicon carbide nanowires (SiC NWs) was smaller than that of Sn solder in the same condition. According to the adsorption theory, SiC NWs would adsorb on the IMC grains and then reduce the surface tension of IMC, which made for the suppression of IMC growth. Also, SiC NWs could nail at grain boundaries and then prohibit the further growth of IMC grains. Thus, doping 0.6 wt% SiC NWs could reduce the size of IMC grains and decrease the diffusion coefficient of IMC growth, which led to prohibiting the interfacial IMC growth at solder/substrate under isothermal aging. During thermal cycling process, SiC NWs addition was beneficial to decrease the rate of IMC growth at the interface of Sn/Cu solder. Moreover, adding SiC NWs into Sn solder could improve the reliability of solder joints in that there were less cracks formed at IMC layer in Sn–SiC/Cu solder.