JP3215410B2 - Manufacturing method of multilayer ceramic capacitor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a multilayer ceramic capacitor.

2. Description of the Related Art In recent years, demand for multilayer ceramic capacitors has been increasing with the miniaturization and higher frequency of electronic devices.

The general manufacturing method of the multilayer ceramic capacitor is as follows. First, a green sheet is prepared by a doctor blade method using a slurry composed of a dielectric powder such as barium titanate, an organic binder, a plasticizer and an organic solvent. Next, the internal electrodes are screen-printed on the sheet. Next, the green sheets on which the internal electrodes are formed are arranged so that the internal electrodes are alternately opposed to each other with the dielectric layer interposed therebetween, and are sequentially laminated. Then, lamination is repeated up to a desired number of laminations to produce a laminated molded body, which is then cut into chips and fired. The sintered body thus obtained is mixed with a SiC abrasive or a grinding stone ball using water as a medium, and after polishing the corners of the chip-shaped ceramic capacitor body in a barrel method, the external electrodes are baked to laminate ceramic capacitors. Has been manufactured. However, this method is not only high in cost due to two firing steps such as firing the external electrode after firing the laminated molded body, but also because the firing temperatures are different, so that the external electrode and the internal electrode are hardened. There is a problem that the mechanical strength of the joint between them is weak. At present, in order to solve these problems, a manufacturing method has been proposed in which an external electrode paste is applied to a surface from which an internal electrode of a laminated molded product is taken out, and then the laminated molded product and the external electrode are simultaneously baked. 54-140959). In this method, since the external electrode and the internal electrode are fired at the same time, the sintering between the external electrode and the internal electrode progresses, so that the mechanical strength of the joint is improved, and the firing step is performed once. The cost can be reduced.

Problems to be Solved by the Invention After applying an external electrode paste to the internal electrode take-out surface of the laminated molded body, in the case of a manufacturing method in which the laminated molded body and the external electrode are simultaneously fired, the corners of the laminated molded body are After polishing, it is necessary to apply an external electrode paste and fire it. However, when the laminated molded body is polished by a method using a SiC abrasive or a whetstone ball with water as a conventional method as in the conventional method, the mechanical strength of the laminated molded body is remarkably lower than that of a sintered body, so that the laminated molded body is easily polished. Cracking and chipping occur in the laminated molded article, and the grain size of the SiC abrasive is small,
Since it is square, there is a problem that the laminated molded article gets into and adheres to the laminated molded article.

The present invention has been made in view of the above problems, and provides a polishing method that does not chip a laminated molded article and does not attach an abrasive when polishing a corner portion of the laminated molded article in a manufacturing process of a ceramic capacitor. .

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a method for polishing a corner of a laminated molded article, which comprises mixing the laminated molded article with wood chips, food powder or a mixture thereof, and polishing the mixture by forced vibration. Is what you do.

Effect of the Invention The present invention uses food powder such as wood chips, corn flour, and walnut powder, or a mixture thereof, which is softer than a laminated molded product, and collides the laminated molded product or the wall of the barrel with the laminated molded product by forced vibration. As a result, the corners are polished, so that the occurrence of cracks and chips can be prevented. Here, when the amount of the polishing medium is extremely large as compared with the laminated molded body, the number of collisions between the laminated molded bodies is drastically reduced, and it is difficult to obtain desired polishing, and it takes a long time for polishing. That is, the desired polishing can be obtained in a short time if the mixing is performed at a mixing volume ratio of 3/1000 or more to the polishing medium of the laminated molded body. Moreover, since the wood chips or food powder used in the present invention have a large particle size, they do not adhere to the laminated molded body unlike SiC abrasives and the like.

Examples Hereinafter, examples of the present invention will be described.

First, using a general method using a barium titanate-based dielectric material, a chip type consisting of 50 layers and a dielectric thickness of 15 μm, in which a dielectric layer and an internal electrode layer are mutually laminated 3.2 ×
A 1.6 × 1.0 mm laminate was produced. Wood chips are combined with the laminated molded product so that the mixing volume ratio of the laminated molded product to the polishing medium is 3/100 in a combination as shown in Table 1 below.
Walnut flour, corn flour or a mixture thereof was sealed in a plastic container and subjected to forced vibration for 30 minutes. After the forced vibration, the radius of curvature (R) was measured in order to confirm the polished state of the corners of the laminate. In addition, the surface of the laminated molded body after polishing was observed. For comparison, Table 1 also shows the results of a conventional method in which a laminated molded body was mixed with a SiC abrasive and a grindstone ball using water as a medium at the same ratio as described above and forcedly vibrated.

As shown in Table 1 above, when wood chips, walnut powder, corn powder or a mixture thereof were used, chipping of the laminated molded product and adhesion of the medium were not observed, and the radius of curvature was also 0.
It was as good as 05mm. In the case of the shape of the laminated molded product used in the present example, the radius of curvature of the corner portion is 0.01 to 0.10 mm as a good product. However, when using a SiC abrasive and a grinding ball, a large number of chips in the laminated molded body occurred, and the abrasive was found to adhere to the surface of the laminated molded body, and the radius of curvature was 0.50 mm.
Greatly exceeded the specified value.

Next, changing the mixing volume ratio of the laminated molded product and the wood chips,
The other conditions are the same as those described above, the forced vibration is performed, and the results of measuring the radius of curvature are shown in Table 2 below.

As shown in Table 2 above, the desired radius of curvature could be obtained when the mixing volume ratio of the laminated molded body to the polishing medium was 3/1000 or more, but below that, the radius of curvature was smaller than the specified value. Was.

Based on the above results, wood chips, food powder or a mixture of these was used as the polishing medium, and the laminated compact was destroyed by forcibly vibrating when the mixing volume ratio of the laminated compact to the polishing medium was 3/1000 or more. It was confirmed that the entire corner was finely scraped off without polishing, and uniform polishing was possible. After polishing, the external electrodes are baked to manufacture a multilayer ceramic capacitor in the same manner as in the related art.

Effect of the Invention As described above, the present invention provides a method for polishing a multilayer molded body by forced vibration using wood chips, food powder or a mixture thereof in a polishing step of a corner of a chip in a manufacturing process of a multilayer ceramic capacitor. As a result, it is possible to eliminate chipping of the laminated molded body and to polish the laminated molded body to a desired radius of curvature, so that productivity of the laminated ceramic capacitor is greatly improved, and its industrial value is extremely large.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Yasutaka Horibe 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-2-101725 (JP, A)

Claims (1)

(57) [Claims] 1. A laminated molded body in which a dielectric layer and an internal electrode are alternately laminated in a container, and only wood chips, food powder or a mixture thereof are sealed before firing, and the container is forcedly vibrated to form the laminated body. A step of polishing the corners of the laminated molded article only by collision between the molded articles or the inner wall surface of the container, the mixing volume ratio of the laminated molded article to the wood chips, food powder or a mixture thereof is 3 / A method for manufacturing a multilayer ceramic capacitor, wherein the number is 1000 or more and 3/10 or less.