Microstructure and mechanical properties of AlN and Cu joint using SnAgTi solder metal

Aluminum nitride (AlN) ceramics copper-clad laminates stand out in the field of electronic packaging for their excellent thermal conductivity, insulation, and stability. Conventional AgCuTi brazing materials produce large residual stresses in the joints. In order to regulate the residual stress, AlN ceramics and oxygen-free Cu were brazed with Sn–Ag–Ti solder. The effects of brazing temperature and Ti content on the microstructure and mechanical properties of the joints were studied. The AlN/SnAgTi/Cu-brazed joint was composed of AlN/Ti diffusion layer/Ti₆Sn₅ + Cu₃Sn + Ag₃Sn + Ti (s, s) + Cu (s, s)/Cu. Both the brazing temperature and titanium content influence the joint structure similarly, which are mainly reflected in the diffusion and aggregation of Ti elements. At low brazing temperature or Ti content, the Ti diffusion layer on the ceramic side was thin and discontinuous. At higher brazing temperatures or Ti contents, the Sn–Ti compounds were found to be agglomerated in large quantities on the ceramic side, which reduced the strength of the joint. At a brazing temperature of 900 °C and a Ti content of 3 wt. %, the shear strength of the brazed joints reached a maximum of 89.8 MPa.