About this Abstract |
Meeting |
2021 TMS Annual Meeting & Exhibition
|
Symposium
|
Electronic Packaging and Interconnections 2021
|
Presentation Title |
Effect of Current Stress on the Microstructure of SnBiAg-SAC Mixed Solder Joints |
Author(s) |
Eric J. Cotts, Faramarz Hadian, Randy Owen |
On-Site Speaker (Planned) |
Eric J. Cotts |
Abstract Scope |
We examined the effect of current stressing on the distribution of Bi in SAC/Bi-SnAg solder joints (mixed assemblies), and in more homogeneous, SnBiAg solder joints. After reflow of mixed assemblies, a large gradient in the concentration of Bi in SnBiAg region of the assemblies was observed. The effects of both heat treatment and electro migration were studied, at temperatures up to 150C and current densities up to 4000 amps/cm2. In this regime, both Bi concentration gradients and the electron wind, were found to be significant driving forces for Bi diffusion. The migration of the Bi atoms could be described using a simple model, with reasonable values for the diffusion coefficient of Bi in Sn, and for the effective charge of Bi. Some indication of the current density limits of such Sn-Bi based solder joints was obtained. |
Proceedings Inclusion? |
Planned: |