JPH11260665A - Manufacture of multilayer ceramic electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce permeation of solvent in a laminated ceramic sheet and prevent swell of the sheet, by making ceramic sheets different in degree of porosity a double-layered structure, and forming a conducting layer on the ceramic sheet side whose degree of porosity is low. SOLUTION: Metal paste 3a turning to an inner electrode is printed in a specified shape on a first ceramic sheet 1a whose degree of porosity is low, by a printing method or the like. The metal paste 3a is dried, and solvent component in the metal paste 3a is almost perfectly evaporated. A second ceramic sheet 2a whose degree of porosity is high is pressed and fixed with pressure on the metal paste 3a side of the first ceramic sheet 1a, and a laminated ceramic sheet 9 having the metal paste 3a in the inside is manufactured. In this time, degree of porosity of the first ceramic sheet 1a is set at least 20%, and that of the second ceramic sheet 2a is set at least 30%. As a result, permeation of solvent in the laminated ceramic sheet is reduced, and swell and dissolution of the sheet are prevented.

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 multilayer ceramic electronic component such as a multilayer ceramic capacitor.

[0002]

2. Description of the Related Art A multilayer ceramic capacitor, which is one of the multilayer ceramic electronic components, has a structure in which a metal paste serving as an internal electrode is printed in a desired shape on a ceramic sheet having a porosity of about 50%. It was fired to provide an external electrode.

[0003]

However, since the ceramic sheet has a high porosity, when the metal paste is printed, the ceramic sheet is swollen or dissolved by an organic solvent contained in the metal paste, and short-circuiting and internal resistance of the internal electrodes are prevented. The resulting multilayer ceramic capacitor has reduced voltage characteristics, and has problems in reliability and quality.

Accordingly, the present invention does not have the above-mentioned problems with respect to the above-mentioned ceramic sheet by forming a ceramic sheet having different porosity into a two-layer structure and forming a conductor layer on the side of the ceramic sheet having low porosity. It is an object of the present invention to provide a multilayer ceramic electronic component.

[0005]

In order to achieve this object, a method for manufacturing a multilayer ceramic electronic component according to the present invention comprises the following steps.
A first step of forming a conductor layer on a ceramic sheet using a metal paste containing at least a metal component and a solvent component, and then laminating a second ceramic sheet on the conductor layer, A second step of obtaining, a third step of laminating a plurality of the laminated ceramic sheets to form a laminated body, and a fourth step of subsequently firing the laminated body. ,
The first ceramic sheet having a lower porosity than the second ceramic sheet is used. By using the first ceramic sheet having a lower porosity, the penetration of the solvent into the multilayer ceramic sheet is reduced, and the multilayer ceramic sheet is used. Since the swelling or dissolution becomes difficult, the above object can be achieved.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention comprises a first step of forming a conductor layer on a first ceramic sheet using a metal paste containing at least a metal component and a solvent component. Then, a second ceramic sheet is laminated on the conductor layer to obtain a laminated ceramic sheet.
And a third step of laminating a plurality of the laminated ceramic sheets to form a laminated body; and a fourth step of subsequently firing the laminated body. The first ceramic sheet comprises: 2 is a method of manufacturing a multilayer ceramic electronic component using a material having a lower porosity than the ceramic sheet of 2, the penetration of a solvent into the multilayer ceramic sheet is reduced, and it becomes difficult to swell or dissolve the multilayer ceramic sheet, It is possible to prevent deterioration of reliability and quality due to short-circuit of the conductor layer and deterioration of electric characteristics such as withstand voltage characteristics.

According to a second aspect of the present invention, there is provided the method for manufacturing a multilayer ceramic electronic component according to the first aspect, wherein the porosity of the second ceramic sheet is 30% or more. In the third step, a sufficient pressure is applied to the portion where the conductor layer is not formed, so that a multilayer ceramic electronic component free from cracks and delamination can be obtained. .

According to a third aspect of the present invention, there is provided the method for manufacturing a multilayer ceramic electronic component according to the first or second aspect, wherein the porosity of the first ceramic sheet is 20% or more. When the conductor layer is formed in the second step by setting the porosity of the sheet to 20% or more,
Infiltration of the solvent into the laminated ceramic sheet is reduced,
Since the laminated ceramic sheet is unlikely to swell or dissolve, it is possible to prevent deterioration of reliability and quality due to deterioration of electrical characteristics such as short-circuit of the conductor layer and withstand voltage characteristics.

According to the present invention, the difference in porosity between the first ceramic sheet and the second ceramic sheet is as follows:
The method for producing a multilayer ceramic electronic component according to any one of claims 1 to 3, wherein the content is 10% or more.
The second ceramic sheet prevents the solvent in the conductor layer from penetrating into the laminated ceramic sheet and absorbs the pressure difference between the conductor layer forming portion and the non-forming portion when the laminate is formed by the second ceramic sheet. can do.

According to a fifth aspect of the present invention, there is provided the method for manufacturing a multilayer ceramic electronic component according to any one of the first to fourth aspects, wherein the thickness of the second ceramic sheet is larger than that of the conductor layer. In the third step, when performing pressure bonding in the third step, it is possible to absorb a pressure difference caused by the thickness of the conductive layer, and a sufficient pressure is applied to a portion where the conductive layer is not formed, so that cracks and delamination are caused. , A multilayer ceramic electronic component free of the problem can be obtained.

According to a sixth aspect of the present invention, the polyethylene in the first ceramic sheet and the second ceramic sheet has a weight average molecular weight of 400,000 or more. In the method for manufacturing a multilayer ceramic electronic component according to any one of the above, the multilayer ceramic sheet having a high porosity can absorb a step due to the presence or absence of a conductor layer.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, taking a multilayer ceramic capacitor as an example.

(Embodiment 1) FIG. 1 is a sectional view of a laminated ceramic sheet according to the present embodiment, FIG. 2 is a sectional view showing one step of a laminated ceramic capacitor, and FIG. 3 is a part of a general laminated ceramic capacitor. FIG.
a is a first ceramic sheet, 2a is a second ceramic sheet, 3a is a metal paste to be the internal electrode 2 formed on the first ceramic sheet 1a, 4a is a metal paste forming part, 5a is a metal paste non-forming part. , 6 indicate a metal upper plate, 7 indicates a metal lower plate, and 8 indicates a distance between the metal upper plate 6 and the metal lower plate 7.

First, a metal to be the internal electrode 2 is formed on a first ceramic sheet 1a having a porosity of 20% and comprising a dielectric powder mainly composed of polyethylene having a weight average molecular weight of 400,000 and barium titanate and having a porosity of 20%. The paste 3a is printed in a predetermined shape. The metal paste 3a contains nickel and a solvent, and the thickness of the metal paste 3a is 3 μm. Next, the metal paste 3a is dried to completely evaporate the solvent component in the metal paste 3a. The drying temperature at this time is desirably 60 ° C. or less so that the polyethylene in the first ceramic sheet 1a does not shrink. Next, a porosity of 60
% Of the second ceramic sheet 2a at a gauge pressure of 5 to 5%.
The first ceramic sheet 1a is pressed and pressed against the metal paste 3a side in the range of 100 MPa to obtain a laminated ceramic sheet 9 having the metal paste 3a inside. Next, a desired number of laminated ceramic sheets 9 each having a metal paste 3a therein are stacked on a plurality of second ceramic sheets 2a laminated such that the metal pastes 3a alternately face each other with the laminated ceramic sheets 9 interposed therebetween. After that, a laminate of a plurality of second ceramic sheets 2a is pressed for several seconds at a gauge pressure of 5 to 100 MPa in the same manner as above to obtain a temporary laminate. At this time, before the number of laminated ceramic sheets 9 on which the metal paste 3a is formed reaches the desired number, a press-bonding step of pressing with the above-mentioned pressure may be added when the laminated ceramic sheets 9 are laminated to some extent. The thickness of the first ceramic sheet 1a is 5 μm, and the thickness of the second ceramic sheet 2a is 5 μm. Thereafter, the temporary laminated body is sandwiched between the upper metal plate 6 and the lower metal plate 7 and is subjected to a uniaxial press at room temperature. Apply pressure. Here, the variation in the interval 8 between the surfaces of the upper metal plate 6 and the lower metal plate 7 is controlled to 40 μm or less. After confirming that sufficient pressure was applied to the temporary laminate, the temperature of the temporary laminate was raised until the maximum temperature reached 150 ° C. to 200 ° C., and the maximum temperature was maintained for about 5 to 60 minutes. A laminate in which the sheets 9 are firmly adhered to each other is obtained. The reason why the maximum temperature of the laminate is set to 150 ° C. to 200 ° C. is that polyethylene is melted from about 150 ° C., and the adhesion between the first ceramic sheet 1a and the second ceramic sheet 2a becomes strong. . The reason why the temperature is set to 200 ° C. or lower is that if the temperature is higher than 200 ° C., the polyethylene is decomposed and does not contribute to the adhesion between the first ceramic sheet 1a and the second ceramic sheet 2a. After that, vertical 3.2
mm, 1.6mm wide chip shape
The polyethylene was removed at 50 ° C. (debuying). The temperature at the time of this debuying, polyethylene can be removed from the laminate,
In addition, it is desirable that the oxidation of nickel in the metal paste 3a is not excessively advanced.
It is desirable to carry out at 0 ° C. Thereafter, firing is performed at a maximum temperature of 1300 ° C. while using a nitrogen gas and a hydrogen gas while maintaining an atmosphere in which nickel in the metal paste 3a is not oxidized. By this firing, a sintered body is obtained in which the ceramic dielectric layer 1 mainly containing barium titanate and the internal electrode 2 mainly containing nickel are sintered simultaneously. Next, copper external electrodes 3 are baked on the exposed end surfaces of the internal electrodes 2 of the sintered body, and after plating, a finished product is obtained.

FIG. 4 shows the effective layer thickness and resistance of a multilayer ceramic capacitor having a size of 3.2 mm in length and 1.6 mm in width and having 100 ceramic dielectric layers 1 (hereinafter referred to as effective layers) between the internal electrodes 2. 4 is a graph showing a relationship with a voltage characteristic. The solid line indicates a multilayer ceramic capacitor using the multilayer ceramic sheet 9 of the present invention as an effective layer, and the dotted line indicates a multilayer ceramic capacitor using a conventional ceramic sheet.

Referring to FIG. 4, in a multilayer ceramic capacitor using a conventional ceramic sheet for the effective layer, the ceramic sheet swells or dissolves due to the permeation of the solvent used for the metal paste. In the case of (1), the withstand voltage characteristics vary. However, when the laminated ceramic sheet 9 of the present invention was used for the effective layer, the variation in the withstand voltage characteristics was very small even when the thickness of the effective layer was 7 μm or less. From this result, as shown in FIG. 5, the short circuit 100 of the internal electrode 2 and the decrease in the withstand voltage characteristic due to the swelling or dissolution of the ceramic sheet, which frequently occurs when the conventional ceramic sheet is laminated, are suppressed. Thus, the yield can be greatly improved.

Needless to say, it is particularly effective for the production of a multilayer ceramic capacitor using nickel as the internal electrode 2 which is required to be highly laminated.

The key points in the present invention are described below. (1) The porosity of the first ceramic sheet 1a is 20%,
Although only the case where the porosity of the second ceramic sheet 2a is 60% is shown, the porosity of the first ceramic sheet 1a is not less than 20% and less than 50%, and the porosity of the second ceramic sheet 2a is 30%. % To less than 80%, and
The same effect can be obtained if the difference in porosity between the two is 10% or more. When the number of laminated ceramic sheets 9 serving as effective layers exceeds 100, it is desirable to use a second ceramic sheet 2a having a porosity of 40% to less than 80%.

(2) Although nickel is used as the material of the internal electrode 2, a base metal such as copper or a noble metal such as palladium or silver-palladium may be used.

(3) In preparing the temporary laminate, not only the pressing but also the heating of the upper metal plate 6 and the lower metal plate 7 to 60 to 120 ° C. may be performed. Here, as described above, the polyethylene in the first ceramic sheet 1a and the second ceramic sheet 2a starts shrinking from 60 ° C. In this step, the metal upper plate 6 and the metal lower plate 7 are not a temporary laminate but a metal laminate. 60
Since the heating is performed to about 120 ° C. and the pressing time is as short as several seconds, the first ceramic sheet 1a and the second ceramic sheet 2a are hardly deformed due to the shrinkage of the polyethylene.

(4) The first ceramic sheet 1a and the second ceramic sheet 2a are formed at the stage of forming a temporary laminate of a binder, a solvent, a plasticizer, a dielectric powder, and the like that form the first ceramic sheet 1a and the second ceramic sheet 2a. The components present in the second ceramic sheet 2a are preferably the same. The reason is that the same component improves the adhesion between the first ceramic sheet 1a and the second ceramic sheet 2a more.

(5) The first ceramic sheet 1a is for preventing the solvent component in the metal paste 3a from penetrating into the laminated ceramic sheet 9 as much as possible. Absorbs the step due to the presence or absence of the first ceramic sheet 1a.
It is more preferable to increase the thickness of the second ceramic sheet 2a than to increase the thickness.

(6) As the solvent in the metal paste 3a, it is preferable to use a solvent having as large a polarity as possible, such as alcohols. The reason is that the first ceramic sheet 1
Since the polyethylene in the second ceramic sheet 2a and the second ceramic sheet 2a are non-polar, the use of a polar solvent can prevent the infiltration of the solvent into the laminated ceramic sheet 9 more.

(7) A plurality of second ceramic sheets 2a are laminated above and below the laminated body. The laminated ceramic sheets are formed in order to absorb a step due to the presence or absence of the internal electrode 2. It is preferable to use a ceramic sheet having a porosity equal to or higher than that of the second ceramic sheet 2a.

(8) In the above embodiment, a multilayer ceramic capacitor has been described as an example. Similar effects can be obtained in the production of electronic components.

[0026]

As described above, according to the present invention, by suppressing the swelling or dissolution of the laminated ceramic sheet, it is possible to suppress the electrical characteristics such as short-circuiting and withstand voltage characteristics of the conductive layer,
The yield can be greatly improved.

[Brief description of the drawings]

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

FIG. 2 is a sectional view showing a crimping step which is one manufacturing step of the multilayer ceramic capacitor according to one embodiment of the present invention;

FIG. 3 is a partially cutaway perspective view of a general multilayer ceramic capacitor.

FIG. 4 is a graph showing the relationship between the thickness of the effective layer of the multilayer ceramic capacitor and the withstand voltage characteristics.

FIG. 5 is a cross-sectional view of a sintered body in which a short circuit has occurred.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic dielectric layer 1a 1st ceramic sheet 2a 2nd ceramic sheet 2 Internal electrode 3a Metal paste 3 External electrode 9 Multilayer ceramic sheet

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuhiro Komatsu 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] 1. A first step of forming a conductor layer on a first ceramic sheet using a metal paste containing at least a metal component and a solvent component, and then forming a second ceramic sheet on the conductor layer. A second step of laminating to obtain a laminated ceramic sheet, a third step of laminating a plurality of the laminated ceramic sheets to form a laminated body, and a fourth step of subsequently firing the laminated body, A method for manufacturing a multilayer ceramic electronic component, wherein the first ceramic sheet has a lower porosity than the second ceramic sheet. 2. The porosity of the second ceramic sheet is 30.
%. The method for producing a multilayer ceramic electronic component according to claim 1, wherein 3. The porosity of the first ceramic sheet is 20.
3. The method for manufacturing a multilayer ceramic electronic component according to claim 1, wherein the content is not less than%. 4. The multilayer ceramic electronic component according to claim 1, wherein a difference in porosity between the first ceramic sheet and the second ceramic sheet is 10% or more. Method. 5. The method for manufacturing a multilayer ceramic electronic component according to claim 1, wherein the thickness of the second ceramic sheet is larger than the thickness of the conductor layer. 6. The polyethylene in the first ceramic sheet and the second ceramic sheet has a weight average molecular weight of 4
The method for manufacturing a multilayer ceramic electronic component according to claim 1, wherein the number is 00000 or more.