Matsushita Electric Works, Ltd.

Hiroaki Takahashi

Izuru Yoshizawa

Tomoyuki Kawahara

Method for plating independent conductor circuit

An undercoat containing copper and bismuth and/or vanadium is formed on a ceramic substrate such as Al.sub.2 O.sub.3. When the undercoat contains copper and bismuth, the ceramic substrate having the undercoat is heated at a temperature between 600.degree. C. and 1100.degree. C. in an oxidative atmosphere to obtain a fired undercoat on the ceramic substrate. The fired undercoat is formed with copper oxide particles and a binder phase containing bismuth and copper for bonding between adjacent copper oxide particles. A bismuth content in the fired undercoat is determined within a range of 10 to 90 wt %. When the undercoat contains copper and vanadium, the ceramic substrate having the undercoat is heated at a temperature between 450.degree. C. and 1100.degree. C. in the oxidative atmosphere to obtain a fired undercoat which is formed with copper oxide particles and a binder phase containing vanadium and copper. A vanadium content in the fired undercoat is determined within a range of 3 to 63 wt %. The copper oxide particles are reduced by the use of a reducing solution to obtain a reduced undercoat having metallic copper particles. The copper particles are partially exposed on a top surface of the reduced undercoat. Copper is coated on the top surface of the reduced undercoat to obtain a copper film on the ceramic substrate.

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Kadoma, Japan

Hiroaki Takahashi