JPH02260509A - Semiconductor ceramic capacitor of particle boundary insulation type - Google Patents

Abstract

PURPOSE:To obtain the titled capacitor efficiently without increase in characteristic variations and deterioration of the characteristics by subjecting the lamination body to a heat treatment in which the powder whose melting point is over 100 deg.C higher than a temperature of the heat treatment exists among the laminated semiconductor ceramic. CONSTITUTION:After the molded body which is formed by mixing and kneading material powder and squeezing out it into a sheet form is put in a baking sheath made of alumina ceramic, it is subjected to sintering for 4 hours at 1450 deg.C in a reducing atmosphere of H2-10% and N2-90%, thereby obtaining a semiconductor ceramic. Next, a diffusion substance comprising Bi-65% and Cu-35% is applied to a surface of the semiconductor ceramic, followed by drying. Furthermore, an alumina powder (a melting point is about 2015 deg.C) whose average particle diameter is 50mum and a zirconia powder (a melting point is about 2677 deg.C) whose average particle diameter is 50mum are deposited on a surface of the semiconductor ceramic, and two semiconductor ceramics are laminated so that the powder is sandwiched between these ceramics and this lamination body is subjected to a heat treatment again at 1200 deg.C for 2 hours in an atmosphere. Then, Ag electrodes are printed on both main surfaces of the resultant semiconductor ceramic of particle boundary insulation type. Thus, the throughput becomes over 7 times as large as a conventional flat-packing method and the capacitors can be manufactured efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a grain boundary insulated semiconductor ceramic capacitor.

[Conventional technology]

A grain boundary insulated semiconductor ceramic capacitor is generally manufactured by the following process.

(2) For example, after mixing raw materials containing 5rTiOs as a main component, a binder and the like are added and kneaded, extrusion molded into a sheet, and the obtained sheet is punched out to obtain a disc-shaped molded body.

(2) A plurality of the above molded bodies are piled up and packed in pods, and fired in a reducing atmosphere to obtain semiconductor porcelain.

■ Applying a grain boundary layer diffusion substance to the surface of the semiconductor porcelain,
A grain boundary insulated semiconductor porcelain is obtained by heat treatment in the atmosphere.

(2) G-electrode layers are formed on each of the principal surfaces of the grain boundary insulated semiconductor ceramic at opposing positions to obtain a grain boundary insulated semiconductor ceramic capacitor.

In the grain boundary insulated semiconductor ceramic capacitor manufactured by the above manufacturing method, when the semiconductor porcelain whose surface is coated with the grain boundary layer diffusion substance is heat-treated in the air, the surface of the semiconductor porcelain coated with the grain boundary layer diffusion substance is heated. The degree of diffusion of the above-mentioned diffusion substance in the grain boundary layer portion of the above-mentioned semiconductor ceramic varies greatly depending on the degree of oxygen supply and heat treatment temperature conditions, etc., and this causes the capacitance C[+F] and dielectric loss jtn6 to
[%], insulation resistance IR [MΩ], and other characteristics vary greatly.

From this point of view, conventionally, in order to prevent the degree of diffusion of the diffusing substance from varying among individual semiconductor porcelains, the firing pod made of a refractory material such as alumina or zirconia was heated directly or from the refractory material. It was common practice to pack the semiconductor porcelain flatly using a setter so as not to 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 throughput per pod, it has been considered to use the above-mentioned semiconductor porcelain as a whole, but the conditions in which each semiconductor porcelain comes into contact with the oxygen atmosphere differs, resulting in large variations in properties, resulting in an increase in dielectric loss and , a decrease in insulation resistance was undeniable.

An object of the present invention is to provide a manufacturing method capable of solving the above-mentioned conventional problems and efficiently obtaining a grain boundary insulated 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 the raw materials of semiconductor porcelain and then molding it.
After firing the obtained molded body in a reducing atmosphere, a grain boundary layer diffusion substance is applied to the surface of the obtained semiconductor porcelain and heat treated in the air, and a pair of grain boundary layer diffusion substances are applied to the surface of the obtained grain boundary insulated semiconductor porcelain. In the method for manufacturing a grain boundary insulated semiconductor ceramic capacitor having an electrode layer formed thereon, when the semiconductor ceramic coated with the grain boundary layer diffusion material is heat-treated in the atmosphere, metal oxides, carbides, and nitrides are removed. Among these, a powder having a melting point higher than the heat treatment temperature by 100° C. or more is prepared, and the semiconductor ceramics are heat-treated while being stacked so that the powder is present between the semiconductor ceramics.

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

[For production]

In the method for manufacturing a grain boundary insulated semiconductor porcelain capacitor of the present invention, the semiconductor porcelains are heat-treated in a stacked state so that powder exists between them, so that heat conduction and oxygen diffusion to each semiconductor porcelain are improved. done evenly.

〔Example〕

Examples of the grain boundary insulated semiconductor ceramic capacitor of the present invention will be described below along with comparative examples.

First, 5tTi03 85a+o1%, ClTiO31
The raw material powder for semiconductor porcelain with a composition ratio of 5ma1% and Nb2030.15mol1% was mixed, and 7v1% of methyl cellulose as a binder and a 10ml1% aqueous solution of glycerin as a plasticizer were added and kneaded. It was extruded into a sheet. Next, the above-mentioned sheet was punched into a disc shape of 10 mm diameter, and the resulting molded body was packed in an alumina porcelain firing sheath.
145 in a reducing atmosphere of yo1%, N2 9Qya1%
Sintering was performed at 0° C. for 4 hours to obtain semiconductor porcelain. Next, 65m of Bl was applied to the surface of the semiconductor porcelain.

A diffusion material containing 1% Cu and 35 moljl of Cu was applied and then dried.

Furthermore, alumina powder with an average particle size of 50++ m (melting point approximately 2
015°C) and zirconia powder (melting point: about 2677°C) with an average particle size of 50jm were prepared and adhered to the surface of the semiconductor ceramic obtained above by the following steps a to 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 test was carried out again under the conditions of Examples 1 to 4 and Comparative Examples 1 to 3 shown in Table 1.
A grain boundary insulated semiconductor porcelain was obtained by heat treatment at ℃ for 2 hours. Note that in Table 1 above, the spacer means a spacer formed from the above powder. A circular shape of 6IIIlφ is formed on each of the two sides of the grain boundary insulated semiconductor porcelain obtained above. Apply polar material paste to 1 and heat 1 at 800℃.
The 0-minute baking process was performed to obtain a sample of a grain boundary insulated semiconductor ceramic capacitor.

For the 6,500 capacitor samples obtained in this way, a measurement frequency of 1 kHz, a measurement voltage of 0, a capacitance C (nF) at IV, a dielectric loss + 1 fl δ (%), and a voltage of 50 V DC were applied for 15 seconds. Insulation resistance IR (
MQIII is set, and the average value 'i, /< -y Tsuki (3
y/i) and the ratio of the throughput per pod, that is, the throughput ratio, and the results are shown in Table 2.

As shown in Table 1, Table 2, and Table 2, all of the samples obtained in Examples 1 to 4 of the present invention had capacitance, dielectric loss, and insulation resistance of the conventional flat packing shown in Comparative Example 1. It has the same characteristics as the samples obtained by the method, and in terms of capacitance and dielectric loss, Comparative Examples 1-
The variation was smaller than that of the sample obtained in No. 3. Also,
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, a grain boundary insulated semiconductor ceramic capacitor can be efficiently manufactured without increasing variation in characteristics or deteriorating characteristics.

Claims (1)

[Claims] The raw materials for semiconductor porcelain are mixed and molded, the resulting molded body is fired in a reducing atmosphere, a grain boundary layer diffusion substance is applied to the surface of the semiconductor porcelain, and then heat treated in the air. In the method for manufacturing a grain boundary insulated semiconductor ceramic capacitor in which a pair of electrode layers is formed on the surface of a grain boundary insulated semiconductor ceramic, the semiconductor ceramic coated with the grain boundary layer diffusion substance is heat treated in the atmosphere. Prepare a powder of a metal or a metal oxide, carbide, or nitride whose melting point is 100° C. or more higher than the heat treatment temperature, and stack the semiconductor ceramics so that the powder exists between them. 1. A method for manufacturing a grain boundary insulated semiconductor ceramic capacitor, the method comprising heat-treating the capacitor in a state where the grain boundary is insulated.