Co-fireable copper multilayered ceramic substrates

The authors discuss the manufacture of co-fireable copper multilayered ceramic substrates utilizing green-tape technology. The substrates were manufactured using an oxidation-reduction reaction, employing CuO paste as an inner-layer conductor. Two types of substrate materials were developed, a crystallizable glass that has good flexural strength, and an amorphous glass which has a low dielectric constant. The burnout process is performed in air. The reduction process is carried out in a nitrogen atmosphere containing 10% hydrogen in which copper oxide is reduced into copper, and sintering is performed in the nitrogen. Low impedance, migration resistance, and low cost have resulted from the use of a Cu conductor