JP3538309B2 - Manufacturing method of multilayer ceramic electronic component - Google Patents

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 In a multilayer ceramic capacitor manufactured by alternately laminating ceramic sheets and conductor layers, the ceramic sheet contains at least a dielectric material such as barium titanate and polyethylene and has a porosity of 30%. % Or more, and the conductor layer was formed using a paste in which a metal powder such as palladium or nickel and a resin component such as ethyl cellulose were mixed.

[0003]

However, according to the above method, an organic solvent is used as a diluent for dissolving a resin component such as ethyl cellulose or adjusting the viscosity of a conductive layer paste which is a mixture of a metal powder and a resin. However, the ceramic sheet is swelled or dissolved by the organic solvent, causing a short circuit of the internal electrode and a decrease in withstand voltage, and has a problem in reliability and quality.

Accordingly, an object of the present invention is to provide a multilayer ceramic electronic component which does not have the above-mentioned problems with respect to the ceramic sheet by using water as a diluent for the conductive paste. .

[0005]

In order to achieve the above object, a method for manufacturing a multilayer ceramic electronic component according to the present invention comprises the steps of:
A plurality of ceramic sheets containing ethylene and ceramic raw materials, and a plurality of conductor layers containing metal, resin, and water are alternately laminated, and first pressurized.
The polyethylene is heated to melt the ceramic sheet.
A first step of the bonding of the bets with each other and firmly to form a laminate, even then a second step of firing the laminate
The above object can be achieved by using water as a diluent so that the ceramic sheet does not swell or dissolve when it enters the ceramic sheet.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention comprises alternately laminating a plurality of ceramic sheets containing polyethylene and ceramic raw materials and a plurality of conductor layers containing metal, resin and water. First, pressurize and hold this pressure
The polyethylene is melted by heating while heating.
A first step of forming a laminate by strengthening the adhesion between Kkushito, then a second step of firing the laminate
A manufacturing method of a multilayer ceramic electronic component having, Serra
By preventing swelling or dissolution of the Mick sheet,
It is possible to prevent short-circuiting of the conductor layer and decrease in withstand voltage, and to improve reliability and quality.

[0007]

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 a water-soluble resin is used as the resin component, and the ceramic sheet swells.
Alternatively, by suppressing dissolution, a short circuit of the conductor layer and a decrease in withstand voltage can be prevented, and reliability and quality can be improved.

[0009] According to a third aspect of the invention, as a resin component, a method of manufacturing a multilayer ceramic electronic component according to claim 1 using a water-dispersed synthetic resin emulsion, Serra
By suppressing the swelling or dissolution of the mic sheet,
It is possible to prevent short-circuiting of the conductor layer and decrease in withstand voltage, and to improve reliability and quality.

[0010] According to a fourth aspect of the invention, in a first step, the polyethylene in the ceramic sheet is a method of manufacturing a multilayer ceramic electronic component of claim 1 the weight average molecular weight of 400,000 or more, porous Since the ceramic sheet has a high degree, a step due to the presence or absence of the conductor layer can be absorbed.

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 cross-sectional view showing one step of a monolithic ceramic capacitor according to the present embodiment, wherein 1a is a ceramic sheet, and 2a is a metal serving as an internal electrode 2 formed on the ceramic sheet 1a. Paste, 4
a indicates a metal paste forming portion, 5a indicates a metal paste non-forming portion, 6 indicates 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. FIG. 2 is a partially cutaway perspective view of a general multilayer ceramic capacitor, wherein 1 is a ceramic dielectric layer, 2 is an internal electrode, and 3 is an external electrode.

First, a ceramic sheet 1 made of polyethylene having a weight average molecular weight of 400,000 and a dielectric powder containing barium titanate as a main component and having a porosity of 70%.
a, a metal paste 2 to be an internal electrode 2 by a printing method
a is formed in a desired shape. This metal paste 2a
Contains 40 to 70% by weight of nickel as a metal component, 2 to 20% by weight of a water-soluble resin component, and 30 to 70% by weight of ion-exchanged water as a diluent. Examples of the water-soluble resin include KW-1 of Sekisui Chemical Co., Ltd., AQ2266 of Lion Corporation, and TB-13 of Daiichi Kogyo Seiyaku Co., Ltd. After removing the moisture in the metal paste 2a from these ceramic sheets 1a, the metal paste 2a is sandwiched between the ceramic sheets 1a.
Are stacked alternately so as to obtain a temporary laminate. Then, this temporary laminated body was sandwiched between the metal upper plate 6 and the metal lower plate 7, and the gauge pressure was 5 to 100 MPa with a uniaxial press at room temperature.
Pressurize in the range of a. Here, the surfaces of the metal upper plate 6 and the metal lower plate 7 that are in contact with the temporary laminate are polished, and the variation in the distance 8 between the surfaces of the metal upper plate 6 and the metal lower plate 7 is controlled to 40 μm or less. Thereafter, it was confirmed that sufficient pressure was applied to the temporary laminate, and the maximum temperature of the temporary laminate was 150 ° C to 200 ° C.
The temperature was raised to ℃ to obtain a laminate. Here, 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 ceramic sheets becomes strong. The reason for setting the temperature to 200 ° C. or less is that
If the temperature is higher than 200 ° C., the polyethylene is decomposed and does not contribute to the adhesion between the ceramic sheets. Thereafter, the chip was cut into a chip shape having a length of 3.2 mm and a width of 1.6 mm, and the polyethylene was removed at 350 ° C. in the atmosphere (debuying). It is desirable that the temperature at the time of the de-buying be such that the polyethylene can be removed from the laminate and the oxidation of the nickel in the metal paste 2a does not proceed too much. Then, the metal paste 2a is formed using nitrogen gas and hydrogen gas.
Sintering is performed at 1300 ° C. while maintaining an atmosphere in which oxidation of nickel in the inside does not proceed excessively. 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, external electrodes 3 made of copper or the like are baked on the exposed both end surfaces of the internal electrodes 2 of the sintered body, plated, and the finished product is obtained.

FIG. 4 is a graph showing the relationship between the effective layer thickness and the withstand voltage characteristic of a multilayer ceramic capacitor having a size of 3.2 mm in length and 1.6 mm in width and having 100 effective layers.
The solid line is a product of the present invention, in which a water-soluble resin is used as a resin component of the metal paste 2a, and ion-exchanged water is used as a diluent. The dotted line is a conventional product in which an organic solvent is used as a diluent.

Referring to FIG. 4, in the conventional multilayer ceramic capacitor, since the ceramic sheet swells or dissolves due to the permeation of the organic solvent used for the metal paste into the ceramic sheet, when the effective layer thickness is 7 μm or less,
Variations in withstand voltage become particularly large. However, the multilayer ceramic capacitor of the present invention in which a water-soluble resin is used as a resin component of the metal paste 2a and ion-exchanged water is used as a diluent has a large variation in withstand voltage characteristics even when the effective layer thickness becomes 7 μm or less. Was small. From this result, as shown in FIG. 3, it is possible to suppress the short circuit 100 of the internal electrode and the deterioration of the withstand voltage characteristic due to the swelling or melting of the ceramic sheet, which frequently occur when the internal electrode is formed using the conventional metal paste. It can be seen that the yield can be greatly improved.

Needless to say, this 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) Although only the case where the porosity of the ceramic sheet 1a is 70% is shown, similar effects can be obtained if the porosity is 30% or more and less than 80%. When the number of effective layers exceeds 100, the ceramic sheet 1a having a porosity of 40 to 75% is used.
It is desirable to use

(2) Although only the water-soluble resin is shown as the resin component contained in the metal paste 2a forming the internal electrode 2, the same effect can be obtained with a water-dispersed synthetic resin emulsion.

(3) Nickel was used as the metal component of the metal paste 2a, but a base metal such as copper, palladium,
A noble metal such as silver-palladium may be used.

(4) Although ion-exchanged water is used as a diluent for the metal paste 2a, it is preferable to use water from which contained ions such as pure water have been removed.

(5) As the water-soluble resin or the water-dispersed synthetic resin emulsion, it is desirable to use one that decomposes at a temperature not higher than the heat treatment temperature during debubbling in order to prevent deterioration of insulation resistance due to residual carbon after firing. .

(6) In the first embodiment, only the multilayer ceramic capacitor has been described. However, the multilayer varistor, multilayer thermistor, multilayer filter, ferrite component, ceramic multilayer substrate, etc., manufactured using the ceramic sheet 1a. A similar effect can be obtained in the manufacture of a die ceramic electronic component.

[0023]

As described above, according to the present invention, even if the diluent in the conductor layer enters the inside of the ceramic sheet, the ceramic sheet does not swell or dissolve, so that the conductor layer is short-circuited and the withstand voltage is reduced. Can be prevented, and improvement in reliability and quality can be achieved. Also, the yield can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a crimping step as one manufacturing step of a multilayer ceramic capacitor according to an embodiment of the present invention.

FIG. 2 is a partially cutaway perspective view of a general multilayer ceramic capacitor.

FIG. 3 is a cross-sectional view of a sintered body in which a short circuit has occurred.

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

[Explanation of symbols]

1 ceramic dielectric layer 1a Ceramic sheet 2 Internal electrode 2a Metal paste 3 External electrodes

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Kurumitsu Hideki               1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric               Kiki Sangyo Co., Ltd. (72) Inventor Kazuhiro Komatsu               1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric               Kiki Sangyo Co., Ltd.                (56) References JP-A-4-196009 (JP, A)                 JP-A-5-190043 (JP, A)                 JP-A-3-273696 (JP, A)

Claims (4)

(57) [Claims] Claims: 1. A material containing polyethylene and a ceramic raw material.
A plurality of ceramic sheets and a plurality of conductor layers containing a metal, a resin, and water are alternately laminated, and firstly, pressure is applied.
The polyethylene is melted by heating while maintaining the pressure.
A first step of forming a laminate by strengthening the adhesion between the ceramic sheets, and a second step of firing the laminate next.
And a method for manufacturing a multilayer ceramic electronic component. 2. The method according to claim 1, wherein the resin is a water-soluble resin . 3. The resin is an aqueous dispersion type synthetic resin emulsion.
The method for producing a multilayer ceramic electronic component according to claim 2, wherein 4. The polyethylene in the ceramic sheet,
The method for producing a multilayer ceramic electronic component according to claim 1, wherein the weight average molecular weight is 400,000 or more .