| About this Abstract |
| Meeting |
2024 TMS Annual Meeting & Exhibition
|
| Symposium
|
Phase Stability, Phase Transformations, and Reactive Phase Formation in Electronic Materials XXIII
|
| Presentation Title |
Effective Suppression of Boron Dopant on the Interfacial Reactions of Electroplating Co(B) Deposits and Lead-free Solders |
| Author(s) |
Chao-hong Wang, Yu-bin Guo |
| On-Site Speaker (Planned) |
Chao-hong Wang |
| Abstract Scope |
Co is known for its superior electromigration resistance, making it a as a viable material for serving as a diffusion barrier in solder joints within electronic devices. Electroless Co deposition with sodium hypophosphite as a reducing agent forms Co(P) layers, but rapid CoSn3 formation and subsequent spalling during reflow soldering are severely disadvantageous for the reliability of solder joints. This study investigated Co(B) deposits using Dimethylamine borane (DMAB) as a Co(P) substitute. The interfacial reactions between lead-free solders and electroplated Co(B) deposits with varying B contents (ranging from 0.8 at.% to 3.2 at.%) were examined. When the B content exceeded 1.3 at.%, the dominant CoSn3 phase was formed. Additionally, a thin Co-Sn-B phase layer was formed, which acted as a diffusion barrier, significantly suppressing the total reaction layer's growth rate by ~90%. Unlike Co(P) deposits, no massive CoSn3 spalling occurred in Co(B) deposits. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Joining, Surface Modification and Coatings, Copper / Nickel / Cobalt |