About this Abstract |
| Meeting |
2026 TMS Annual Meeting & Exhibition
|
| Symposium
|
Electronic Packaging and Interconnection Materials III
|
| Presentation Title |
Thermal Expansion of Near-Eutectic Sn-Bi Solder: Effects of Temperature Ramp Rate and Bi Dissolution |
| Author(s) |
Xin Fu Tan, Stuart D. McDonald, Tetsuro Nishimura, Kazuhiro Nogita |
| On-Site Speaker (Planned) |
Xin Fu Tan |
| Abstract Scope |
Sn-Bi alloys are promising low temperature solders. Thermal expansion is a critical property in solder alloys, as mismatches between solder, substrate and die can lead to mechanical failure. Literature shows that Bi dissolution in Sn with increasing temperature is kinetically limited, leading to potential deviations from equilibrium thermal expansion depending on the temperature ramp rate. This work examines the thermal expansion of the near-eutectic Sn-58wt.%Bi alloy between 25-130°C using dilatometry, at temperature ramp rates of 2 and 5°C per minute. The alloy exhibits non-linear expansion with increasing temperature, reaching peak expansion at 90.3 °C and 100.7 °C for temperature ramp rates of 2 and 5 °C per minute, respectively. Beyond these temperatures, the alloy contracts with further heating. This behaviour is attributed to the combined effect of a decreasing Bi volume fraction following its dissolution in Sn, along with corresponding changes in the unit cell volume of Sn crystals. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Electronic Materials, Characterization, |