JPH02260511A - Manufacture of surface reoxidation type semiconductor porcelain capacitor - Google Patents

Abstract

PURPOSE:To manufacture a semiconductor porcelain capacitor with good efficiency without causing any increasing in variety of characteristics and deterioration of characteristics by performing heat treatment in a piled-up state so that powder exist between semiconductor porcelains. CONSTITUTION:At the time of heat treatment of a semiconductor porcelain in the atmosphere, powder of that, whose melting point is higher than heat treatment temperature by more than 100 deg.C, of an oxide, carbide and nitride of a metal, is prepared for performing heat treatment in a piled-up state so that powder may exist between the semiconductor porcelains. Accordingly, thermal conduction to each semiconductor porcelain and oxygen diffusion are uniformly performed. Thereby, an increase in variety of characteristics and deterioration of a characteristics are prevented: this results in a semiconductor porcelain capacitor with good efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of production] The present invention relates to a method for manufacturing a surface reoxidation type semiconductor ceramic capacitor.

[Conventional technology]

The surface reoxidation type semiconductor ceramic capacitor is manufactured by the following steps in the film.

(2) For example, after mixing raw materials containing s Bs7i03 as a main component, adding a binder and the like, kneading, extruding into a sheet, and punching out the obtained sheet to obtain a disc-shaped molded body.

(2) A plurality of the above molded bodies are piled up and packed in pods, fired in the atmosphere, and then the obtained sintered body is heat treated in a reducing atmosphere to obtain semiconductor porcelain.

(2) The above-mentioned semiconductor porcelain is heat-treated again in the atmosphere to re-oxidize the surface to obtain a surface-reoxidized semiconductor porcelain.

(2) Ag electrode layers are formed at mutually opposing positions on both main surfaces of the surface reoxidation type semiconductor ceramic capacitor to obtain a surface reoxidation type semiconductor ceramic capacitor.

In the surface reoxidation type semiconductor ceramic capacitor manufactured by the above manufacturing method, depending on the degree of oxygen supply to the surface of the semiconductor ceramic and the conditions of the heat treatment temperature when the semiconductor ceramic is heat-treated in the atmosphere again, the semiconductor ceramic The degree of oxygen diffusion in the surface layer of
Its characteristics such as capacitance C [nF], dielectric loss jsnJ (%), and insulation resistance IR [MΩ) vary greatly.

From this point of view, conventionally, in order to prevent the degree of oxygen diffusion from varying among individual semiconductor porcelains, a setter made of the above-mentioned refractory material was placed directly on top of the firing pod made of a refractory material such as alumina or zirconia. Via
It was common practice to pack the semiconductor porcelain pieces flat so that they did not overlap each other, and then stack these pods in multiple stages and heat-treat them in the atmosphere.

[Problem to be solved by the invention]

However, in the conventional manufacturing method described above, semiconductor porcelain was packed flat and heat-treated on top of a refractory firing pod or setter so that they did not overlap each other, so the number of semiconductor porcelains that could be processed per pod was limited. Both thermal efficiency and processing efficiency were low.

In addition, in order to increase the amount of processing per pod, it is being considered to heat treat multiple sheets of the semiconductor porcelain described above, but the characteristics of each semiconductor porcelain vary widely, resulting in an increase in dielectric loss and a decrease in insulation resistance. I couldn't deny it.

An object of the present invention is to provide a manufacturing method capable of solving the above-mentioned conventional problems and efficiently obtaining a surface reoxidation type semiconductor ceramic capacitor without increasing variation in characteristics or deteriorating characteristics. There is a particular thing.

[Means to solve the problem]

The present invention involves mixing raw materials, molding the resulting molded product, firing it in the air, heat-treating it in a reducing atmosphere, and then heat-treating it again in the air to re-oxidize the surface. In a method for manufacturing a surface re-oxidized semiconductor ceramic capacitor in which a pair of electrode pentode layers are formed on the surface of an oxidized semiconductor ceramic, when the semiconductor ceramic is heat-treated in the atmosphere again,
Prepare powders of metal oxides, carbides, and nitrides whose melting points are 100°C or more higher than the heat treatment temperature, and heat-treat the semiconductor porcelains in a stacked state so that the powders are present between the semiconductor porcelains. This is a method of manufacturing a surface reoxidation type semiconductor ceramic capacitor.

Specific materials for the powder include, for example, alumina, zirconia, magnesia, or a mixed composition thereof.

[For production]

In the method for manufacturing a surface reoxidation type semiconductor ceramic capacitor of the present invention, the heat treatment for reoxidation is performed while the semiconductor ceramics are stacked so that the powder is present between each semiconductor ceramic. uniform heat conduction and oxygen diffusion.

〔Example〕

Next, examples of the method for manufacturing a surface reoxidation type semiconductor ceramic capacitor of the present invention will be described together with comparative examples.

First, B*ri(h 92io1N, CtOz 5
Semiconductor porcelain raw material powder with a composition ratio of 1% MO and 1% Ti023TSO was mixed, and 7v1% methylcellulose as a binder and a 10wj% aqueous solution of glycerin as a plasticizer were added and kneaded. It was extruded into a sheet. Next, the above-mentioned sheet was punched out into a disc shape of 10 mmφ, and the obtained molded body was packed in an alumina porcelain firing pod, and then exposed to ts in the air.
A sintered body was obtained by firing at oo°C. Next, the above-mentioned sintered body was packed into the firing pod again, and 82 10 mm 01%, th 9
A heat treatment was performed for 2 hours at 1000''C in a reducing atmosphere of 0yo1% to obtain semiconductor porcelain.

Furthermore, alumina powder with an average particle size of 50 m (melting point: approximately 201
5° C.) and zirconia powder (melting point: about 2677° C.) with an average particle size of 501° C. were prepared and adhered to the surface of the semiconductor ceramic obtained above by the following method B-d.

a. The above semiconductor porcelain was placed in a container containing the above powder, and the container was vibrated to cause the above powder to adhere to the surface of the semiconductor porcelain.

b. The above semiconductor porcelain was placed in a container containing the pulverized coumaron resin powder and the above powder, and mixed, and the above powder and the coumaron resin powder were attached to the surface of the semiconductor porcelain by the generated static electricity.

The above C0 powder and an aqueous PVA solution as an organic binder were mixed, and the above semiconductor porcelain was immersed in the mixture and then pulled up and dried to adhere the above powder to the surface of the semiconductor porcelain.

d. A liquid mixture of the powder and an aqueous PVA solution as an organic binder was sprayed onto the surface of the semiconductor ceramic and dried to adhere the powder to the surface of the semiconductor ceramic.

Using the semiconductor porcelain obtained above, the temperature was increased to 900°C in the atmosphere again under the conditions of Examples 1 to 4 and Comparative Examples 1 to 3 shown in Table 1.
A heat treatment was performed for 2 hours to obtain a surface reoxidized semiconductor porcelain. In Table 1, the term "spacer" means a spacer formed from the above powder. Ag electrode material paste was applied in a circular shape of 6 m φ on both sides of the surface reoxidation type semiconductor porcelain obtained above, and baked at 1.800℃ for 10 minutes to test the surface reoxidation type semiconductor porcelain capacitor. I got a fee.

For the 6,500 capacitor samples obtained in this way, the measurement frequency was 1kHz, the measurement voltage was 0.4VC', the capacitance C[nF], g[lt loss 1*nδ(%), O, and the voltage of 50V DC were measured at 15 Insulation resistance IR after applying for seconds
(Measure MQI, average value = 1 variation (3σ/ma),
The ratio of the throughput per pod, that is, the throughput ratio, was determined and the results are shown in Table 2.

As shown in Table 1, Table 2, and Table 2, all the samples obtained in Examples 1 to 4 of the present invention have capacitance, dielectric loss, insulation resistance, and the conventional flat packing shown in Comparative Example 1. It had the same characteristics as the samples obtained by this method, and had smaller variations in capacitance and dielectric loss than the samples obtained in Comparative Examples 2 and 3.

In addition, in terms of the throughput per pod, the throughput was more than seven times that of the conventional flat packing method.

In the above embodiments, alumina or zirconia was used as the powder, but the present invention is not limited to this. Among metals, metal oxides, carbides, and nitrides,
It is possible to use various powders selected from powders having a melting point 100° C. or more higher than the heat treatment temperature.

〔Effect of the invention〕

According to the present invention, as shown in the results of the above examples, surface reoxidation type semiconductor ceramic capacitors can be efficiently manufactured without increasing variation in characteristics or deteriorating characteristics.

Claims (1)

[Claims] The raw materials for semiconductor porcelain are mixed and then molded, the resulting molded body is fired in the air, heat treated in a reducing atmosphere, and then heat treated again in the air to reoxidize the surface. In a method for manufacturing a surface reoxidation type semiconductor ceramic capacitor in which a pair of electrode layers is formed on the surface of a type semiconductor ceramic, metals or metal oxides, carbides, and nitrides are removed when the semiconductor ceramic is heat-treated in the atmosphere again. Of things,
A surface reoxidation type semiconductor porcelain characterized by preparing a powder having a melting point higher than the heat treatment temperature by 100°C or more, and heat-treating the semiconductor porcelain in a stacked state so that the powder exists between the semiconductor porcelains. Method of manufacturing capacitors.