| About this Abstract |
| Meeting |
2021 TMS Annual Meeting & Exhibition
|
| Symposium
|
Phase Stability, Phase Transformations, and Reactive Phase Formation in Electronic Materials XX
|
| Presentation Title |
Effect of Initial Volume Ratio and Reflow Temperature on the Microstructure of SnBiAg-SAC Mixed Solder Joints |
| Author(s) |
Eric J. Cotts, Faramarz Hadian, Randy Owen, Mohammed Genanu |
| On-Site Speaker (Planned) |
Eric J. Cotts |
| Abstract Scope |
Significant phase transformations occur in mixed assembly SAC/Bi-Sn solder joints (e.g., SAC305/Sn57Bi1Ag) during standard processing procedures. The changes in microstructure of these mixed assemblies during reflow (140C to 215C) depend upon the peak temperature, and on the initial ratio of the volume of the SnBiAg paste to the volume of the SnAgCu solder ball. The final volume ratio between the volumes of the SnAgCu and SnBiAg phases can be predicted as a function of the peak reflow temperature. Prolonged heating of such mixed assemblies accelerates diffusion of Bi in to the SAC region, resulting in recrystallization of the Sn in the SAC. The newly formed, high energy grain boundaries provide pathways for relatively rapid diffusion of Bi. Transformation rates are characterized and reported. Values of the shear strength of the mixed assemblies as a function of peak reflow temperature and initial volume ratio are also reported. |
| Proceedings Inclusion? |
Planned: |