Effect of Sn content on filler and bonding characteristics of active metal brazed Cu/Al2O3 joint

Abstract

This study examined the effects of the Sn content in a pure active metal filler Ag-Cu-Ti for the brazing of a Cu/Al2O3 joint. The optimal content of Sn to effectively wet alumina was 5 wt%. The microstructure of the brazed joint showed the presence of an Ag-rich matrix and a Cu-rich phase, and Cu-Ti intermetallic compounds were observed along the bonded interface. The intermetallic compounds (IMCs) in the filler are found to increase when the Sn content in the alloy approaches to 10 wt%. These results suggest an extremely significant bonding strength of Cu/Al2O3 joint using the Ag-Cu-Ti+Sn filler. The shear strength of the brazed joint increased with Sn content up to 5 wt%, reaching a maximum at ≈15 MPa. In addition, the strength decreased when the Sn content was higher than 5 wt%.