On Low-Temperature Brazing of AlN Ceramics and Al:Design of Brazing Material, Microstructure and Properties of Joint

This study addresses the lack of brazing materials suitable for low-temperature brazing of AlN ceramics and Al. By adding elements In and Sn to AgCuTi brazing materials to lower their melting points, new low-temperature brazing materials Ag-28Cu-35In-2Ti and Sn-19Ag14.35Cu-17.5In-1Ti were prepared to achieve good bonding of AlN/Al joints. The low-temperature brazing process, joint microstructure and properties of AlN ceramics and Al using two types of brazing materials were explored. Results show that for Sn-19Ag-14.35Cu-17.5In-1Ti brazing materials relatively stable compounds such as InSn3 and Al3Ti form at the solder joints. Ag-28Cu-35In-2Ti brazing material generates relatively stable compounds such as Al2Cu, AgIn2, and TiAl3 at the solder joint, and the joint strength increases with the increase in welding temperature. To prevent the diffusion and precipitation of In, Ni plating is chosen on the surface of Al, but it reduces the thermal conductivity of the joint. It is found that using Ag-28Cu-35In-2Ti brazing material for welding contributes to the highest joint strength of 20.28 MPa at 640 degrees C for 30 min; under the condition of 620 degrees C for 15 min, the thermal diffusion coefficient can reach 65.941 m(2)/s. This brazing material provides a new method for highly reliable connection of AlN ceramics/Al.