Facile synthesis of Cu-Sn nanoparticle film and its bonding mechanism for power electronic packaging

The Cu-Sn full intermetallic compound is a promising high-temperature electronic packaging material, while its preparation is usually time-consuming. In this work, a novel dual-beam laser co-deposition method was proposed to prepare Cu-Sn nanoparticle film for power electronic packaging with high bonding efficiency. Various Cu-Sn contents were prepared to reveal the bonding mechanism of the full intermetallic compound structure. The results show that joints with a Cu content ranging from 20 wt% to 80 wt% could form full intermetallic compounds within 2 min with the shear strength reaching 120 MPa. Specifically, Cu₆Sn₅, 'island-like' Cu₃Sn, and sintered Cu generated successively in the bondline center with the increasing Cu content. All failures occurred within the bondline indicating a higher interface bonding quality, while the 'island-like' Cu₃Sn enhanced the shear strength. This die attach process is compatible with current commercial SiC die attach process with lower material cost as well as high efficiency, enabling the Cu-Sn nanoparticle film to be a promising material for high-reliability power electronic packaging.