Thick film metallization of AlN substrate with Cu conductive pastes

Metallization of AlN substrate is employed with Cu conductive pastes through a thick-film screen printing process. The morphological development of the conductive/substrate interface and the element distribution of the compound precipitates are investigated with the aid of electron microscopy and X-ray diffraction. For higher sintering temperature paste Cu 1, the reaction of PbO₂ and W forms PbWO ₄ and results in the reduction of Cu₂O to metallic Cu. The as-sintered Cu 1 metallized specimen exhibits higher adhesion strength than the lower sintered Cu 2 specimen. It is argued that the more highly densified film morphology, the compound formation, and mechanical interlocking are the major factors in the enhancement of the adhesion strength. It is also observed that the sintering atmosphere has a significant effect on the distribution of the morphological development of precipitates near the conductive/substrate interface