JP2002237428A - Method of manufacturing ceramic electronic part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic electronic part which has required characteristics. SOLUTION: Ceramic sheets 10 formed of polyethylene and dielectric powder and conductor layers 11 formed of a metal component and an organic material other than polyethylene are alternately laminated to form a laminate. Then, the laminate is burned, and an external electrode 3 is formed on the exposed surface of the conductor layer 11.

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 ceramic electronic component such as a multilayer ceramic capacitor.

[0002]

2. Description of the Related Art FIG. 8 is a partially sectional perspective view of a multilayer ceramic capacitor which is one of ceramic electronic components.
1 is a ceramic dielectric layer, 2 is a conductor layer, 3 is an external electrode, and the conductor layer 2 is connected to the external electrode 3 respectively.

Hereinafter, a method for manufacturing a conventional multilayer ceramic capacitor will be described.

[0004] First, a metal paste to be a conductor layer 2 is printed in a desired shape on a ceramic sheet to be a ceramic dielectric layer 1 by a printing method. Next, a plurality of ceramic sheets on which the metal paste is printed are prepared, and a plurality of the ceramic sheets are stacked so that the conductor layers 2 alternately face each other with the ceramic sheet interposed therebetween to obtain a stacked body.

After that, the laminate was fired to form external electrodes 3 on both end surfaces where the conductor layer 2 of the sintered body was exposed.

[0006]

However, according to the above method, when the porosity of the ceramic sheet is high, the metal component penetrates into the ceramic sheet because the metal paste is printed directly on the ceramic sheet.

In recent years, multilayer ceramic capacitors have been made to have a thin ceramic sheet in order to achieve a high capacitance. In this case, a short circuit occurs between conductive layers due to a metal component penetrating into the ceramic sheet. Had problems.

Accordingly, an object of the present invention is to provide a method of manufacturing a ceramic electronic component with few short-circuit defects.

[0009]

To achieve this object, the present invention comprises the following manufacturing method.

[0010] The first invention of the present invention is directed to a first method for producing a laminate by alternately laminating at least a ceramic sheet composed of a ceramic component and polyethylene, a metal component and a conductor layer composed of one or more kinds of organic substances. And a second step of firing the laminated body, wherein the organic substance is a method for producing a ceramic electronic component, which is an organic substance other than polyethylene, wherein penetration of a metal component into a ceramic sheet is suppressed, Short-circuit failure between conductor layers can be suppressed.

The second invention is the method for manufacturing a ceramic electronic component according to the first aspect, wherein the melting point of the organic substance is higher than the melting point of polyethylene, and the shape accuracy of the laminate can be improved.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings, taking a multilayer ceramic capacitor as an example.

(Embodiment 1) FIGS. 1 to 6 are sectional views showing a lamination process of a multilayer ceramic capacitor according to an embodiment of the present invention.
Is a conductor layer, 12 is a base film, 13 is a metal press plate, and 14 is a temporary laminate.

First, as shown in FIG. 1 (a), a plurality of ceramic sheets 10 having a porosity of 50% and a thickness of 10 μm made of a dielectric powder mainly composed of polyethylene and barium titanate having a weight average molecular weight of 400,000. prepare.

On the other hand, a metal paste containing nickel as a metal component, ethyl cellulose, an acrylic resin, a butyral resin as a binder, benzyl butyl phthalate as a plasticizer, and an aliphatic or aromatic solvent as a solvent was prepared. 2), a metal paste is printed in a desired shape on a base film 12 such as polyethylene terephthalate and dried to form a plurality of conductor layers 11 having a thickness of 2.5 μm.

The base film 12 has no adverse effect even if pressure or heat is applied in a later step. By this drying, most of the solvent in the conductor layer 11 is scattered and the surface is hardened, and almost all of the metal component, the plasticizer and the binder component are left alone. Specifically, the organic component in the conductor layer 11 is 5 to 100% by weight of the metal component.
The content is 15 wt%, preferably 8 to 12 wt%. The reason is that if the amount is less than 5% by weight, the adhesiveness to the ceramic sheet 10 is deteriorated. is there.

Next, as shown in FIG. 2, a plurality of ceramic sheets 10 are laminated on a press plate 13 and a conductive layer 11 is formed on a base film 12 on an ineffective layer formed by pressing.
Each time, after lamination so that the conductor layer 11 is in direct contact with the ceramic sheet 10, pressure is applied using the upper and lower press plates 13 via the base film 12 to bond the conductor layer 11 and the ceramic sheet 10. This pressurization is performed in a temperature range from room temperature to a temperature at which the plasticizer in the conductive layer 11 does not scatter too much (150 ° C. in the present embodiment).
The binder component and the plasticizer component contained in the conductor layer 11 are softened, and the adhesion between the conductor layer 11 and the ceramic sheet 10 is improved. The reason is that if the plasticizer is scattered too much, the conductor layer 11 becomes hard and brittle, and the ceramic sheet 10
This is because the adhesive strength between the conductive layer 11 and the conductive layer 11 is reduced, which causes a problem of causing a structural defect during lamination or firing. When the content of the plasticizer and the binder in the conductor layer 11 is low, the temperature at the time of pressurization is increased to activate the plasticizer and the binder to improve the adhesion between the two. On the other hand, when the content is high, sufficient adhesion between the two can be obtained even at room temperature.

Next, the base film 12 is released from the conductive layer 11 as shown in FIG. At this time, in order to easily release the conductive layer 11 and the base film 12, an acrylic resin,
It is effective to form the conductor layer 11 after forming a release layer (not shown) made of at least one of melamine resin, epoxy resin and silicon resin. Particularly, in a mixed system of an acrylic resin and a melamine resin, a desired release property can be obtained. In addition, silicone resin is effective in that desired release properties can be obtained and solvent resistance and moisture resistance are excellent.

Thereafter, as shown in FIGS. 4 and 5, the ceramic sheet 10 is laminated on the conductor layer 11 again under the same conditions and pressed, and as shown in FIG. Are laminated again and pressed.

In this manner, the ceramic sheet 10 and the conductor layer 11 are laminated a desired number of times so that the conductor layers 11 alternately face each other with the ceramic sheet 10 interposed therebetween, and a temporary laminate 5 shown in FIG. 6 is obtained.

Next, the entire temporary laminated body 5 is subjected to a main pressure of 15%.
After pressurizing at 0 ° C. and 80 MPa for 1 minute, it is cut into a desired shape, and degreased and fired. The condition of the main pressurization is at a temperature not lower than the melting temperature of the polyethylene in the ceramic sheet 10 and lower than the decomposition temperature and in a pressure range of 5 to 100 MPa. It is preferable that the degreasing is performed in the order of first removing the plasticizer in the laminate, and then removing the binder by increasing the temperature. The reason is that when heated at once to remove the plasticizer and the binder at once, a new compound is generated by the plasticizer and the binder and remains in the laminate even after degreasing, and this compound burns during firing. This is because structural defects such as delamination occur by being removed from the laminate, and the occurrence rate of short-circuit defects increases.

Further, conditions for degreasing and baking are set so that nickel serving as the conductive layer 11 is not excessively oxidized.

By this firing, a sintered body is obtained in which the ceramic dielectric layer 1 mainly containing barium titanate and the conductor layer 2 mainly containing nickel are sintered simultaneously. Next, external electrodes 3 made of copper or the like are baked on the exposed end surfaces of the conductor layer 2 of the sintered body, and after plating thereon, a finished product as shown in FIG. 8 is obtained.

(Embodiment 2) Hereinafter, Embodiment 2 of the present invention will be described with reference to the drawings.

In the first embodiment, after laminating the ceramic sheet 10 on the ineffective layer, the sheet is pressed, and the conductive layer 1 is further placed thereon.
1, the base film 12 is disposed so that the conductor layer 11 is in direct contact with the ceramic sheet 10, and is pressed through the base film 12 using the upper and lower press plates 13.
The conductor layer 11 and the ceramic sheet 10 are adhered.

The second embodiment is largely different from the first embodiment in that the ceramic sheets 10 are not simply pressed each time they are laminated, but are simply laminated, and a conductor layer is formed thereon. When pressing after laminating 11, the adhesiveness between the ceramic sheets 10 and between the ceramic sheet 10 and the conductor layer 11 are simultaneously to be ensured.

Thereafter, a completed product is obtained in the same manner as in the first embodiment. As compared with the first embodiment, the number of times of pressurization is reduced by half. This pressurizing process requires a time of about 1 to 30 seconds / time, and as the number of laminations increases, more time is required. In particular, when the conductive layer 1 is formed of a base metal, the effect of the lamination process is enormous because the ratio of the lamination process to the product price is large.

Therefore, in the second embodiment, the number of times of pressurization can be halved as compared with the first embodiment, which can contribute to cost reduction.

(Embodiment 3) Hereinafter, Embodiment 3 of the present invention will be described with reference to the drawings.

The third embodiment differs greatly from the first and second embodiments in that the ceramic sheet 10 and the conductor layer 1 are different.
After the ceramic sheet 10 with the conductor layer 11 is obtained by arranging the conductor layers 11 of the base film 12 with direct contact so as to be in direct contact with each other and integrating them by applying pressure, they are laminated.

Specifically, the ceramic sheet 10 and the base film 12 formed in the same manner as in the first and second embodiments
As shown in FIG. 7, a ceramic sheet 10 and a base film 1 are placed between two rollers 15 as shown in FIG.
2 and the conductor layer 11 are sandwiched simultaneously, and the ceramic sheet 10 and the conductor layer 11 are bonded to each other. Thereafter, the base film 12 is peeled off, cut into a desired shape, and
The ceramic sheet 10 with 1 is obtained.

Next, lamination and pressurization of the ceramic sheet 10 with the conductor layer 11 on the ineffective layer are repeated until a desired number of laminations is obtained, thereby obtaining a temporary laminate 14. At this time, in the case where the conductor layer 11 is laminated so that the conductor layer 11 is on the upper side, for example, the conductor layer 1 is prevented from adhering to the upper press plate 13.
It is important to provide a sheet between the press plate 1 and the press plate 13 so that the conductor layer 11 does not adhere thereto. Therefore, it is desirable that the ceramic sheet 10 be on the upper side.

The subsequent steps are the same as in the first embodiment.

When the ceramic sheet 10 with the conductor layer 11 is manufactured by using the roller 15 as in the third embodiment, it can be performed at a relatively high speed. That is, in the third embodiment, as compared with the first embodiment, the number of times of pressurization at the time of lamination can be reduced by half, which can contribute to cost reduction.

Table 1 shows a multilayer ceramic capacitor having 150 effective layers (the number of ceramic dielectric layers 1 sandwiched between the conductor layers 2) manufactured by the conventional method and the first to third embodiments. Represents the short-circuit rate.

[0036]

[Table 1]

As is clear from Table 1, the multilayer ceramic capacitors according to the first to third embodiments have a drastically reduced short-circuit rate as compared with the related art. Further, as a result of analyzing the internal cross section of the short product, the short was a short between the conductive layers 11.

Therefore, according to the present invention, the conductive layer 1
Dramatically reduce shorts between 1 and greatly improve yield,
And it can contribute to cost reduction.

In each of the above embodiments, a multilayer ceramic capacitor has been described. However, a ceramic electronic component such as a multilayer varistor, a multilayer thermistor, a multilayer coil, and a ceramic multilayer substrate is formed by laminating a ceramic sheet 10 and a conductor layer 11. Has the same effect.

The conductive layer 11 has the same effect of reducing short-circuit defects whether it is a noble metal or a base metal, but is very effective when a base metal is used in terms of reducing the cost of the product. Further, by using an organic substance other than polyethylene as the organic substance contained in the conductor layer 11, the conductor layer 11 is softened by pressurization and heating at the time of forming the laminated body, so that it is possible to prevent the conductor layer 11 from entering the ceramic sheet 10.

The effect of the present invention is greater as the porosity of the ceramic sheet 10 is higher. Particularly, when the ceramic sheet 10 having a porosity of 30% or more is used, an excellent effect is exhibited.

[0042]

According to the present invention described above, a metal paste is not directly printed on a ceramic sheet, but is transferred onto a ceramic sheet after being formed on a base film, so that organic components in the conductor layer are reduced. As a result, the flowability is lowered, and the penetration of the conductor layer into the ceramic sheet can be suppressed to a minimum. Therefore, the occurrence of short-circuit failure of the ceramic electronic component can be extremely suppressed, and the yield can be improved. In particular, the ceramic sheet is thin and has a great effect on the improvement of the retention of the multilayer chip capacitor which requires high lamination.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view of a ceramic sheet according to one embodiment of the present invention. FIG. 1B is a cross-sectional view of a conductor layer according to one embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a stacking step according to one embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a stacking step according to one embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a stacking step according to one embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a stacking step according to one embodiment of the present invention.

FIG. 6 is a cross-sectional view of a temporary laminate according to one embodiment of the present invention.

FIG. 7 is a cross-sectional view illustrating a stacking step according to one embodiment of the present invention.

FIG. 8 is a partial cross-sectional perspective view of a general multilayer ceramic capacitor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic dielectric layer 2 Dielectric layer 3 External electrode 10 Ceramic sheet 11 Conductive layer 12 Base film 13 Press plate 14 Temporary laminated body 15 Roller

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideki Kuramitsu 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Terms (reference) 5E082 AB03 BC36 EE04 EE21 FG06 FG26 FG54 LL01 LL02 MM24

Claims (2)

[Claims] A first step of alternately laminating a ceramic sheet composed of at least a ceramic component and polyethylene, a metal component and a conductor layer composed of at least one kind of organic material to form a laminate, and then laminating the laminate. And a second step of firing the body, wherein the organic substance is an organic substance other than polyethylene. 2. The method according to claim 1, wherein the melting point of the organic substance is higher than the melting point of polyethylene.