Reaction layer formation in nitride ceramics(Si3N4 and AlN) to metal joints bonded with active filler metals.

Abstract

Bonding of nitride ceramics (Si3N4 and AlN) to metals was carried out in a vacuum of about 6 mPa using Cu-base active filler metals. Reaction layers existed at the interfaces between Si3N4 or AlN and insert layers, and Cu enriched layers were found in the bonding layers. Reaction layers in Si3N4 to W joints were composed of nitrides and silicides of active metals, and those in AlN-Cu joints were composed of nitrides of active metals. The thermodynamic calculation suggested that these products were formed by the reactions between nitride ceramics and the melted active filler metals. It was elucidated that the growth behavior of the reaction layer in Si3N4-W joints could be expressed by the Johnson-Mehl type equation with a time exponent 'n' of 1/2. It was deduced that the growth of reaction layers were controlled by the diffusion process of active metals in the reaction layers.