| About this Abstract |
| Meeting |
2020 TMS Annual Meeting & Exhibition
|
| Symposium
|
Advanced Microelectronic Packaging, Emerging Interconnection Technology and Pb-free Solder
|
| Presentation Title |
A Model Study of Bi Diffusion and Intermetallic Growth in Sn-Bi Low Temperature Soldering Systems |
| Author(s) |
Yaohui Fan, Yifan Wu, John Blendell, Nilesh Badwe, Carol A. Handwerker |
| On-Site Speaker (Planned) |
Yaohui Fan |
| Abstract Scope |
A new low temperature interconnect technology based on Sn-Bi alloys is being considered for attaching Sn-Ag-Cu (SAC) solder BGAs to circuit boards at temperatures significantly lower than for homogeneous SAC joints. Microstructure development studies of reflow and annealing, including Bi diffusion and precipitation, are important in understanding mechanical reliability and failure paths in the resulting heterogeneous joints. Experiments in several SAC-SnBi geometries revealed that Bi concentration profiles deviate from local equilibrium expected from the phase diagram, with much higher local concentrations and lower volume fractions of liquid than expected during short-time high temperature anneals in the two-phase region. A preliminary model based on Bi interface segregation model was constructed for predicting Bi diffusion and distribution characteristics in Sn during annealing. Rapid (Ni,Au)Sn4 intermetallic growth was also observed at Ni-Sn interface during solid-state annealing in SnBi-ENIG assemblies but is reduced if silver is added to Sn-Bi eutectic. |
| Proceedings Inclusion? |
Planned: Supplemental Proceedings volume |