JPH05283275A - Manufacture of laminated ceramic capacitor - Google Patents

Abstract

PURPOSE:To enhance the production yield of the title capacitor by restraining delamination. CONSTITUTION:A laminated ceramic capacitor is manufactured by laminating ceramic green sheets. Each of the green sheets comprises a PET film 1 on which an internal electrode layer 2 is printed with paste, and the internal electrode layer 2 is covered with dielectric slurry 3. Since the solvent used in the dielectric slurry is not the type to dissolve the binder of the paste, the dissolution of the binder does not occur and thus the internal electrode layer 2 is prevented from swelling. As a result, the surface difference in level of each ceramic green sheet becomes extremely small, and no delamination is caused even when many ceramic green sheets are laminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a monolithic ceramic capacitor.

[0002]

2. Description of the Related Art In a conventional method of manufacturing a monolithic ceramic capacitor, first, a dielectric material containing barium titanate as a main component is kneaded with an organic vehicle containing a binder component to prepare a dielectric slurry. Next, this dielectric slurry is applied onto a polyethylene terephthalate film (hereinafter referred to as a PET film) as a support by a doctor blade method or the like and then dried, and further an internal electrode containing fine metal powder such as palladium as an electrode material. An internal electrode layer is printed on the surface using a paste, and this is dried to produce a ceramic green sheet. Then, after separating the ceramic green sheets from the PET film, a plurality of them are laminated and cut into a predetermined size to produce a laminated body. Next, this laminated body is fired and external electrodes are formed to manufacture a laminated ceramic capacitor.

As a manufacturing method different from the above, various manufacturing methods have been proposed in which an electrode-embedded ceramic green sheet for forming a dielectric layer is laminated on an internal electrode layer formed on a support. There is.

[0004]

However, in the above-mentioned prior art, since the internal electrode layers are formed on the dielectric layer, when a large number of ceramic green sheets are laminated,
The thickness of the internal electrode layer causes a step between the ceramic green sheets, and especially when the number of layers is high, there is a problem that the adhesion between the ceramic green sheets is insufficient and the laminated ceramic capacitor causes delamination. ..

Also in the case of an electrode-embedded ceramic green sheet, when the solvent in the dielectric slurry and the binder in the internal electrode paste are compatible, the internal electrode paste is applied and dried, and then the dielectric slurry is applied. Then, the solvent in the dielectric slurry permeates and swells the binder in the internal electrode layer. Due to the swelling of the binder, there is a problem that the same delamination as described above is caused to promote the surface step difference between the portion having the internal electrode layer and the portion having no internal electrode layer in the ceramic green sheet.

The present invention solves such a problem, and an object of the present invention is to provide a method for manufacturing a laminated ceramic capacitor which suppresses the occurrence of delamination and has a high production yield.

[0007]

In order to achieve this object, a method for manufacturing a multilayer ceramic capacitor according to the present invention is to apply an internal electrode paste to the surface of a support to form an internal electrode layer, and to form the internal electrode paste. A dielectric slurry containing a solvent insoluble in the binder contained in is applied to the surface of the support so as to cover the internal electrode layers to produce a ceramic green sheet, which is laminated and fired. To produce a monolithic ceramic capacitor.

[0008]

According to this structure, since the solvent of the dielectric slurry is an insoluble solvent for the binder of the internal electrode paste, the internal electrode paste is applied on the support and dried, Even if the dielectric slurry is applied onto the electrode layer, the internal electrode layer does not swell, and a ceramic green sheet having almost no surface step can be obtained. Therefore, by using this ceramic green sheet, the adhesion between the ceramic green sheets becomes strong, and the laminated ceramic capacitor in which delamination does not occur can be easily manufactured.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing a monolithic ceramic capacitor according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a partial sectional view of a ceramic green sheet according to this embodiment. In FIG. 1, 1 is a PET film that is a support, 2 is an internal electrode layer, and 3 is a dielectric layer.

Next, a method for manufacturing a monolithic ceramic capacitor using such a ceramic green sheet will be described.

First, an electrode paste made of palladium powder, ethyl cellulose as an organic binder component, and α-terpineol as a solvent was prepared. Further, a dielectric material containing barium titanate as a main component was dispersed in methylamyl acetate as an organic solvent together with a polybutyl alcohol resin binder and a plasticizer to prepare a dielectric slurry. The electrode paste was screen-printed on the PET film 1 as a support so as to have a dry film thickness of 5 μm in a predetermined pattern and then dried to form the internal electrode layer 2.

Next, the dielectric slurry is applied by a doctor blade method to one side of the PET film 1 on which the internal electrode layer 2 is formed so that the dry film thickness is 20 μm, and further dried to form the dielectric layer 3. did. This is 100mm × 10
A ceramic green sheet was produced by cutting into a size of about 0 mm. Then, after peeling off the ceramic green sheet from the PET film 1, 50 layers are arranged so that the internal electrode layers 2 face each other with the dielectric layer 3 interposed therebetween,
Further, after pressure bonding, it was cut into a desired size to obtain a green chip. Then, after degreasing this green chip in the atmosphere at 350 ° C. using a box-type electric furnace,
A sintered body was obtained by firing at ° C, and external electrodes were formed on this sintered body to produce a laminated ceramic capacitor.

In this example, the following evaluation was carried out at an intermediate stage of this manufacturing process. First, the difference in thickness between the portion having the internal electrode layer 2 of the ceramic green sheet and the portion not having the internal electrode layer 2 was measured as a surface step. Next, the incidence of delamination in the sintered body produced using this ceramic green sheet was investigated. For comparison, the conventional method, that is, the dielectric slurry was used for P
A ceramic green sheet which was dried on an ET film after coating, printed with an internal electrode layer on the ET film, was dried as a conventional product A, and a PET film containing a binder insoluble in the solvent in the dielectric slurry. The internal ceramic paste which is not printed is dried after printing, the dielectric slurry is applied on it by the doctor blade method, and the dried ceramic green sheet is used as the conventional product B, and the same measurement is performed on the sintered body of the laminated ceramic capacitor using these. I went.

The results of these measurements are shown in (Table 1). However, the delamination occurrence rate in (Table 1) shows the ratio of the number of delamination observed in each of 200 sintered bodies.

[0016]

[Table 1]

As is clear from (Table 1), the laminated ceramic capacitor according to the present embodiment does not cause delamination at all and has an extremely excellent effect.

In this example, the internal electrode paste used ethyl cellulose as a binder and methylamyl acetate, which is insoluble in ethyl cellulose as a solvent for the dielectric slurry, was used. The combination with a solvent is not limited, and the following combinations are also effective. That is, for ethyl cellulose, lactate-n-isoamyl lactate, diethyl ether, butylene glycol and the like are effective in addition to methylamyl acetate.

Further, since ethyl cellulose is insoluble in water, a water-soluble one such as polyvinyl alcohol type polymer, acrylic type polymer or ethylene oxide polymer may be used as the binder of the dielectric slurry. ..

[0020]

As is apparent from the above description, according to the present invention, a ceramic green sheet is prepared by using a solvent of the dielectric slurry which is insoluble in the binder of the internal electrode, and the ceramic green sheets are laminated. By manufacturing the monolithic ceramic capacitor in this manner, a monolithic ceramic capacitor in which delamination does not occur can be easily manufactured, and a great effect is obtained in improving the production yield of the monolithic ceramic capacitor.

[Brief description of drawings]

FIG. 1 is a partial sectional view of a ceramic green sheet according to an embodiment of the present invention.

[Explanation of symbols]

 1 PET film (support) 2 internal electrode layer 3 dielectric layer

Claims (1)

[Claims] 1. An internal electrode paste is applied to the surface of a support to form an internal electrode layer, and then a dielectric slurry containing a solvent insoluble to the binder contained in the internal electrode paste is applied to the internal electrode. A method for producing a monolithic ceramic capacitor, wherein a ceramic green sheet is produced by coating the surface of the support so as to cover the layers, and the ceramic green sheet is laminated and then fired.