Low-Temperature Cu–(Sn–Bi) Solid Liquid Interdiffusion Bonding – An Initial Study

This work is an initial study of the metal system Cu-(Sn-Bi) for low-temperature solid-liquid interdiffusion (SLID) bonding. Different samples were prepared with a bonding temperature set to 155 °C and bonding times varying from 10 minutes to 24 hours to study the evolution of the bond-line. Bonded samples were characterized through cross-sectional microscopy, using scanning electron microscopy imaging and energy-dispersive x-ray spectroscopy. Successful bonds were achieved for all samples, and the growth of the CU
6
Sn
5
phase was observed over time. Although Cu
3
Sn phase was not found in any of the samples, the results suggest that this phase can be achieved in the bonds by modifying some parameters in the process, like, the thicknesses of the metals and/or the applied pressure during the bonding process.