Bonding Mechanism and Microstructure of Bonded Zone of AlN Ceramics with Ti-AgCu Brazing Metal

Metallization and bonding of AIN ceramics were made using active brazing metal (Ti-AgCu). Active brazing metal used in metallization and bonding was in paste form prepared by adding Ti powder and organic solvent in to eutectic silver brazing metal powder. Characterization and bonding mechanism of the bonded layer, and relation between the thichness of the reacted layer and bonding strength were studied. The results of this study are as follows : (1) The microstructure of the bonded layer between AIN ceramics and Ti-AgCu brazing metal is found to be TiN layer of about 0.2 to 0.8 μm in thickness at the AIN interface, a composite layer of TiC, AICu as a middle layer and Ag-Cu alloy layer at the surface side. (2) Thickness of TiN layer did not change by the amount of Ti addition in silver brazing metal but the thicness of TiCu and AlCu layers are increased with increase of Ti addition in silverbrazing metal. Activation energy of growth of TiN layer is found to be 20 kJ/mol. (3) When the amount of Ti addition is more than 15 mass%, the bonding strength is decresed and the bonded layer is broken. Because the thickness of brittle TiCu layer increases with the increase of the Ti cotent in silver brazing metal.