Narumi China Corporation

Hiroshi Kawabe

Susumu Nishigaki

Junzo Fukuda

Shinsuke Yano

Masashi Fukaya

A multilayer ceramic substrate with multilayered circuit patterns, the improvement in which internal conductors for wiring are formed by a Ag base conductive materials capable of being co-fired with multilayered green ceramic substrate sheets in an oxidizing atmosphere and external conductors electrically connected with the internal conductors are formed by a Cu base conductive material, the external Cu conductors being formed in such a manner so that a liquid phase of Cu-Ag is not formed at the interface of the Cu conductor and the Ag conductor. Further high reliable resistors of RuO.sub.2 or Bi.sub.2 Ru.sub.2 O.sub.7 type may be integrally formed onto and/or inside the substrate. In such an arrangement, problems or difficulties caused due to Ag migration, incomplete binder removal, solder leaching, etc., are eliminated and thereby there can be a multilayer substrate with a high reliability and a high pattern precision.

Multilayer ceramic substrate with circuit patterns

In a multilayer ceramic circuit board comprising a substrate, an insulating layer on the substrate, and a conductive pattern on the insulating layer, an additive of Cr.sub.2 O.sub.3 or MnO.sub.2 is added to the insulating layer to reinforce adhesion between the insulating layer and the conductive pattern. Each of the substrate and the insulating layer is manufactured by firing at a temperature between 800.degree. C. and 1000.degree. C., alumina particles and a glass composition comprising an alumina component. When a total amount of alumina in the substrate is equal to or greater than that in the insulating layer, an amount of Cr.sub.2 O.sub.3 or MnO.sub.2 is restricted to a range between 0.1% and 10.0% by weight, with a difference between the total amounts of alumina falling within a range between 0% and 30% by weight. When the total amount of alumina in the substrate is smaller than that in the insulating layer, the amounts of Cr.sub.2 O.sub.3 and MnO.sub.2 may be between 0.1% and 10.0% by weight and between 0.1% and 15% by weight, respectively. The difference between the total amounts of alumina may be between 0% and 20% by weight.

Growing community of inventors

Nagoya, Japan

Hiroshi Kawabe