Bonding Strength and Microstructure of SnAg-Based Solid Liquid Inter-Diffusion Bonds

Abstract

Solid Liquid Inter-diffusion (SLID) is a new technology used as interconnects in high density and 3 dimensional packages. This manuscript investigates effect of process parameters, pressure, time and temperature on the strength of bonds and microstructure produced using this technology. A full factorial experiment is designed and implemented on the process with these 3 variables at 3 levels using Sn3.5Ag. Bonds’ strength were then measured using a micro-tester and load displacements were monitored. This analysis shows that SLID bonds form at temperatures much higher than melting temperature of the low melting material. It also shows that time is a significant factor. Bonds that are formed under 10 minutes of time do not show a significant amount of intermetallics. Although the elemental percentage of copper is high in the middle of the bond, it does not reach enough to form any of intermetallic compounds of this ternary system. The specimens fabricated under longer time around 1 hour showed a more brittle, intermetallic like behavior.