Matsushita Electric Works, Ltd.

Izuru Yoshizawa

Hiroaki Takahashi

Tomoyuki Kawahara

Masayuki Ishihara

Susumu Kajita

Satoru Ogawa

Kiyotaka Waki

Noboru Yamaguchi

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.

Method of coating a copper film on a ceramic substrate

A method for roughening a ceramic substrate surface includes a step of sequentially taking out part of roughening a treatment bath of phosphoric acid into which the ceramic substrate is dipped prior to a formation on the substrate of conductor a layer, and subjecting the part of the bath taken out sequentially to regeneration treatment. Any increase in the viscosity due to dehydrating condensation of the roughening bath can be thereby effectively restrained to prolong effective life of the bath. Further, the surface roughened ceramic substrate can be provided thereon with conductor layers smoothly formed by means of a plating and eventually with a circuit pattern as well as a resistor formed on the pattern within an inert gas atmosphere.

Method for roughening ceramic substrate surface and method for

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Kadoma, Japan

Izuru Yoshizawa