An estimate of Si3N4 diffusion into Cu based filler metal

The diffusion phenomena occurring at the boundary between Si3N4 and active Cu based filler metal during Si3N4/metal joining are discussed as a part of the general theory of reaction layer growth. The mechanism of reaction layer formation is explained in the light of wettability, heterogeneous chemical reactions and diffusion in the presence of a moving interface. Observed processes involve diffusion steps in conjunction with chemical reactions at solid/liquid boundary. Illustrative calculation results based on the proposed procedure are presented. ©