About this Abstract |
Meeting |
2021 TMS Annual Meeting & Exhibition
|
Symposium
|
Electronic Packaging and Interconnections 2021
|
Presentation Title |
Reconciling Phase Equilibria and Crystal Structures for the Cu6Sn5 Intermetallic in the Cu-Sn System |
Author(s) |
Andreas Leineweber |
On-Site Speaker (Planned) |
Andreas Leineweber |
Abstract Scope |
The Cu6Sn5 region of the Cu-Sn phase diagram is perhaps the most basic part of fundamental knowledge for understanding the processes in solder joints involving Sn-based solders and Cu-based substrates. The most prominent phase diagrams imply a high-temperature η and a low-temperature η’ phase. The η phase has a Ni2In/NiAs structure whereas η’ is an ordered variant thereof. Later reported structures called η8, η6 and η4+1 were not connected to the phase diagram.
New insight on the phase diagram obtained by X-ray diffraction and microstructure analysis on dedicatedly heat-treated Cu-Sn alloys are presented. The analyses reveal a significant and temperature dependent homogeneity range of the disordered eta phase as well as existence of an incommensurate η’’ phase closely related to η’ which develops from Cu-rich eta phase upon low-temperature annealing. Implications of the crystallographic and constitutional insight for the heat treatment of solder joints will be discussed. |
Proceedings Inclusion? |
Planned: |