Structural Evolution of Hexagonal η-Cu6Sn5 under Electrical Current Stress: An In-Situ Study

Shubhayan Mukherjee^1*, Shih-kang Lin^1,2,3

¹Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan
²Hierarchical Green-Energy Materials (Hi-GEM) Research Center, National Cheng Kung University, Tainan, Taiwan
³Program on Smart and Sustainable Manufacturing, Academy of Innovative Semiconductor and Sustainable Manufacturing, National Cheng Kung University, Tainan, Taiwan

* Presenter:Shubhayan Mukherjee, email:shubhayan.edu.29@gmail.com

The reliability of electronic packaging is impacted by high current densities due to the formation of intermetallic compounds (IMCs) like Cu6Sn5 at the Sn-Cu interface. Cu6Sn5 has two phases: a high-temperature hexagonal η phase and a low-temperature monoclinic η' phase. This study examines hexagonal η-Cu6Sn5 under electrical current stress. Phase purity was confirmed via SEM and XRD. In-situ synchrotron radiation-based XRD was employed to monitor real-time structural changes under current. Lattice parameter shifts were calculated to assess phase stability, and density functional theory (DFT) simulations explored the effects of electron mobility on structural evolution.

Keywords: Hexagonal η-Cu6Sn5, Electric current stressing, Synchrotron radiation-based XRD, Structural Change