Method for producing boundary layer semiconductor ceramic capacitors

• US 4,380,559 A
• Filed: 09/25/1980
• Issued: 04/19/1983
• Est. Priority Date: 09/25/1980
• Status: Expired due to Term

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Yamaguchi, Masami, Mandai, Haruhumi, Kohno, Yoshiaki, Nishimura, Kunitaro
• Primary Examiner(s): Lusignan, Michael R.
• Assistant Examiner(s): Bueker, Richard
• Application Number:
  US06/190,711
• Time in Patent Office: 936 Days
• Field of Search: 427/80, 427/81, 427/126.3, 427/185, 427/242, 427/248.1, 427/251, 427/252, 427/255, 427/255.3, 427/255.5, 427/213, 427/215, 427/217, 427/85, 427/89, 264/61
• US Class Current: 427/80
• CPC Class Codes: H01G 4/1281 with grain boundary layer

Abstract

A method for producing boundary layer semiconductor ceramic capacitors comprises firing shaped bodies of a semiconductor ceramic material in a neutral or reducing atmosphere, heat-treating the resultant semiconductor ceramic bodies to insulatorize crystal grain boundaries of the semiconductor ceramics, and providing opposite electrodes on surfaces of the heat-treated semiconductor ceramic bodies and is characterized in that said heat-treating is carried out by heating the semiconductor ceramic bodies together with power of an insulatorizing agent with stirring in a neutral or oxidizing atmosphere at a temperature ranging from 950° to 1300° C. As a semiconductor ceramic material, there may be used semiconductor ceramics of a barium titanate system, or of a strontium titanate system, or a complex semiconductor ceramic mainly comprising barium titanate or calcium titanate and strontium titanate. This method enables one to produce boundary layer semiconductor ceramics as good quality with small standard deviation and high yield.

Claims

1. A method for producing boundary layer semiconductor ceramic capacitors, comprising the steps of:

firing shaped bodies of a semiconductor ceramic material in a neutral or reducing atmosphere;

heat-treating the resultant semiconductor ceramic bodies to insulatorize crystal grain boundaries of the semiconductor ceramics; and

providing opposite electrodes on surfaces of the heat-treated semiconductor ceramic bodies;

characterized in that said heat-treating is carried out by heating the semiconductor ceramic bodies together with powder of the insulatorizing agent with stirring in a neutral or oxidizing atmosphere.

2. The method according to claim 1 wherein the semiconductor ceramic material is a barium titanate system semiconductor ceramic.

3. The method according to claim 1 wherein the semiconductor ceramic material is a strontium titanate system semiconductor ceramic.

4. The method according to claim 1 wherein the semiconductor ceramic material is a complex semiconductor ceramics mainly comprising barium titanate and strontium titanate.

5. The method according to claim 1 wherein the semiconductor ceramic material is a complex semiconductor ceramics mainly comprising strontium titanate and calcium titanate.

6. The method according to claim 1 wherein the heat-treating is carried out at a temperature ranging from 950°

to 1300°

C.

7. The method of claim 6 wherein the semiconductor ceramic material is a strontium titanate system semiconductor ceramic.

8. The method of claim 7 wherein the insulatorizing agent comprises Bi₂ O₃, Pb₃ O₄ and CuO.

9. The method of claim 8 wherein said heat-treating is carried out in a vessel and said stirring is effected by agitating said vessel.

10. The method of claim 1 wherein said heat-treating is carried out in a vessel and said stirring is effected by agitating said vessel.