Supersaturated Ag-Cu nanoalloy film for high reliability power electronic packaging

Nano-Ag sintering can realize superior thermal, electrical, and mechanical properties for power electronic packaging, while it suffers from unstable microstructure and electrochemical migration. In this work, a super-saturated Ag2.8 wt%Cu nanoalloy film has been developed using pulsed laser deposition, which can be sintered at 250 degrees C in air for electronic packaging without sacrificing bondability. It was surprisingly found that both thermal stability and electrochemical migration resistance were significantly improved when alloying the Ag with 2.8 wt% Cu. The in situ formed Cu2O/CuO from Ag-Cu nanoalloy existed on the pore surface and along the grain boundaries of Ag/Ag-Cu nanoalloy, which stabilized the microstructure of bondline from 400 h to 1400 h at 300 degrees C. The synergistic effect of Ag-Cu nanoalloy and Cu oxides realized an obvious protective effect in the process of anodic dissolution, exhibiting a short-circuit time 2.4 times of the pure Ag electrode. The die attach process is compatible with most commercial equipment and Si/SiC dies with improved performance, enabling the supersaturated Ag-Cu nanoalloy to be a promising material for high reliability power electronic packaging.

Automated summary

In this work, a super-saturated Ag2.8 wt%Cu nanoalloy film was fabricated using pulsed laser deposition. The thermal stability and electrochemical migration resistance of the nanoalloy were significantly improved by alloying Ag with 2.8 wt% Cu. The synergistic effect between Ag-Cu nanoalloy and Cu oxides provided a protective effect during anodic dissolution.