About this Abstract |
| Meeting |
2020 TMS Annual Meeting & Exhibition
|
| Symposium
|
Advanced Microelectronic Packaging, Emerging Interconnection Technology and Pb-free Solder
|
| Presentation Title |
A Preliminary Study of the Dissolution of Bi in β-Sn using In Situ Scanning Electron Microscopy |
| Author(s) |
Andre M. Delhaise, Peter Banh, Dian Yu, Hong Ran Wang, Jason Tam, Jane Howe, Doug D. Perovic |
| On-Site Speaker (Planned) |
Andre M. Delhaise |
| Abstract Scope |
The inclusion of bismuth (Bi) in lead (Pb)-free solder alloys causes stabilization in mechanical properties after aging. Bi precipitates dissolve into the β-tin (Sn) matrix upon heating, and precipitate out uniformly upon cooling, creating a homogenous microstructure. Bi-bearing alloys also outperform traditional Pb-free alloys in accelerated thermal cycling (ATC). However, it is unknown whether Bi strengthens the alloy via solid solution or precipitation during each phase of the thermal cycle.
A preliminary study was conducted to understand the kinetics of Bi dissolution in β-Sn using in situ Scanning Electron Microscopy (SEM). Binary Sn-Bi samples with 3, 6, or 9wt% Bi were sectioned, then heated at either 65°C or 90°C in SEM. Sn-6Bi samples were also pre-aged to look at the effects of Bi precipitate distribution. Images were taken periodically during heating. A mathematical model is proposed to define the visible precipitate area as a function of heating time. |
| Proceedings Inclusion? |
Planned: Supplemental Proceedings volume |