JP3873922B2 - Manufacturing method of ceramic electronic component - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a ceramic electronic component such as a multilayer ceramic capacitor.
[0002]
[Prior art]
A conventional method for manufacturing a ceramic electronic component will be described by taking a multilayer ceramic capacitor as an example.
[0003]
A ceramic sheet is produced using ceramic raw material powder and an organic substance such as a binder or a plasticizer.
[0004]
In addition, a metal paste to be an internal electrode is produced using metal powder and a binder.
[0005]
A plurality of the ceramic sheets are laminated to produce a second ceramic layer, and a ceramic sheet to be the first ceramic layer and an internal electrode produced using a metal paste are alternately laminated thereon. Then, a plurality of ceramic sheets are again laminated thereon to produce a second ceramic layer to obtain a laminate.
[0006]
Since the second ceramic layer is produced by laminating a plurality of ceramic sheets, it is thicker than the first ceramic layer.
[0007]
Next, the laminate is integrated by heating and pressing, and then cut into a desired shape and fired.
[0008]
Next, by forming external electrodes on both end faces of the multilayer body, a multilayer ceramic capacitor is obtained.
[0009]
As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
[0010]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-67578
[Problems to be solved by the invention]
When a plasticizer is contained in the ceramic sheet, the physical properties change depending on the storage period and storage state. However, the ceramic sheet containing no plasticizer has low adhesive strength, and the second ceramic layer that is not laminated alternately with the internal electrodes has insufficient adhesive strength between the sheets, and the second ceramic layer peels off. It had the problem that.
[0012]
Therefore, an object of the present invention is to provide a method for manufacturing a ceramic electronic component that can suppress the peeling of the second ceramic layer even when a ceramic sheet containing no plasticizer is used.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has the following configuration.
[0014]
According to the first aspect of the present invention, in particular, the first ceramic layer containing no plasticizer and the internal electrode containing the plasticizer are alternately laminated, and the second ceramic containing no plasticizer on the upper and lower sides. in the laminate in which a layer, by heating and holding the laminate predetermined time, after a plasticizer contained in the internal electrode is diffused into the second ceramic layer, and is then burned, the fluidity of the plasticizer The plasticizer is diffused in the second ceramic layer faster and the adhesive strength between the first ceramic layer and the second ceramic layer is improved, so that peeling of the second ceramic layer can be suppressed.
[0015]
In the invention described in claim 2 of the present invention, in particular, the first and second ceramic layers have a network structure, and the plasticizer can be easily diffused, so that the first ceramic layer and the second ceramic layer can be diffused. Since the adhesive strength is improved, peeling of the second ceramic layer can be suppressed.
[0016]
The invention described in claim 3 of the present invention uses a phthalic acid plasticizer as a plasticizer, and since the molecular weight is not larger than that of a resin usually used for ceramics, it is diffused in the second ceramic layer. It is easy to improve the adhesive strength between the first ceramic layer and the second ceramic layer, and to suppress the peeling of the second ceramic layer.
[0017]
The invention according to claim 4 of the present invention uses, in particular, the first and second ceramic layers having a porosity of 50% or more. The plasticizer is easily diffused in the second ceramic layer. The adhesive strength between the ceramic layer and the second ceramic layer is improved, and the peeling of the second ceramic layer can be suppressed.
[0018]
In the invention described in claim 5 of the present invention, in particular, the density difference between the first ceramic layer and the second ceramic layer after pressurizing the laminate is 0.1 g / cm ³ or less. Since the shrinkage ratio during firing does not differ greatly, the peeling of the second ceramic layer can be suppressed.
[0021]
In the invention according to claim 6 of the present invention, in particular, the particle size of the inorganic powder forming the second ceramic layer is 1.0 μm or less, and generally the smaller the particle size of the inorganic powder, Although it is difficult to improve the density of the second ceramic layer, when the thermocompression bonding is performed by diffusing the plasticizer, the ceramic particles inside the ceramic sheet easily flow and the density of the second ceramic layer is sufficiently increased. Can be improved.
[0022]
In the invention according to claim 7 of the present invention, in particular, the plasticizer in the metal paste is 4 to 6 wt% of the metal component, and the plasticizer is easily diffused in the second ceramic layer. The adhesive strength between the ceramic layer and the second ceramic layer is improved, and peeling of the second ceramic layer can be suppressed.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the first embodiment will be used to explain the present invention, in particular, the invention described in claims 1 to 7 , using a multilayer ceramic capacitor.
[0024]
FIG. 1 is a cross-sectional view of the multilayer ceramic capacitor according to the first embodiment, in which 11 is a first ceramic layer, 12 is a second ceramic layer, 13 is an internal electrode, and 14 is an external electrode.
[0025]
First, a ceramic sheet having a porosity of 50% or more is produced using polyethylene having a weight average molecular weight of 400,000 or more and a ceramic raw material powder mainly composed of barium titanate.
[0026]
The ceramic sheet becomes the first and second ceramic layers 11 and 12 and has a network structure. That is, polyethylene has a network structure and is layered, and the ceramic powder is adsorbed on this network, and eventually the ceramic powder also has a network structure.
[0027]
Also prepared is a metal paste in which nickel cellulose is added as ethyl cellulose, acrylic resin, butyral resin, plasticizer is benzyl butyl phthalate, and aliphatic or aromatic solvent is added as a solvent, and an internal electrode is formed on a base film such as a polyethylene terephthalate film. A plurality of 13 are formed. As a plasticizer, 4 to 6 wt% of nickel is added. The plasticizer is not necessarily added to the metal paste to be the internal electrode 13, and even if added, it is usually about 3 wt%. In the present embodiment, diffusion to the second ceramic layer 12 is promoted by setting the amount of the plasticizer to be 4 to 6 wt% of the metal component.
[0028]
Further, in order to facilitate the release of the internal electrode 13 and the base film in a later process, a release layer composed of at least one of acrylic resin, melamine resin, epoxy resin, and silicon resin is previously formed on the base film. It is desirable to print the internal electrode 13 after the formation. In particular, in a mixed system of acrylic resin and melamine resin, desired releasability can be obtained. In addition, the silicon resin is effective because it provides desired release properties and is excellent in solvent resistance and moisture resistance.
[0029]
Next, the internal electrode 13 and the base film are laminated on the ceramic sheet to be the first ceramic layer 11, and the internal electrode 13 is transferred to the first ceramic layer 11 by pressing and heating from the base film, and then the base film is transferred. The film is peeled off to produce the first ceramic layer 11 with internal electrodes.
[0030]
Next, a desired number of first ceramic layers 11 with internal electrodes are laminated on a second ceramic layer 12 formed by laminating a plurality of ceramic sheets, and then a second ceramic in which a plurality of ceramic sheets are laminated. The layer 12 is laminated | stacked and a laminated body is obtained.
[0031]
Basically, the first ceramic layer 11 is composed of a single ceramic sheet, and the second ceramic layer 12 is composed of a plurality of ceramic sheets.
[0032]
When laminating the first ceramic layer 11 with internal electrodes, pressurization and heating are performed. The pressurization is 115 MPa, the heating is 130 ° C., the first ceramic sheets are bonded together, and the internal electrodes 13 The plasticizer contained in is diffused. However, the plasticizer is not uniformly diffused in the laminate.
[0033]
Further, by holding the laminate at 60 ° C. for 24 hours, the plasticizer of the internal electrode 13 is uniformly diffused into the second ceramic layer 12 and the adhesive strength between the layers is improved. At this time, since the first and second ceramic layers 11 and 12 have a porosity of 50% or more and have a network structure as described above, the plasticizer is easily diffused.
[0034]
It is desirable to hold the laminate at a temperature at which the fluidity of the plasticizer is promoted. However, in order to maintain the shape of the laminate, it is desirable that the melting point of the polyethylene or less. Therefore, 60 ° C. or more and 140 ° C. or less is desirable.
[0035]
Then, the whole laminated body is pressurized and heated at 150 MPa and 165 ° C. to be integrated.
[0036]
Thereafter, the multilayer body is cut into a desired shape, degreased, fired, and the external electrode 14 is formed on the exposed end face of the internal electrode 13 to obtain the multilayer ceramic capacitor shown in FIG.
[0037]
This multilayer ceramic capacitor has excellent characteristics without peeling of the second ceramic layer 12.
[0038]
Furthermore, since no plasticizer is added to the ceramic sheets constituting the first and second ceramic layers 11 and 12, there is no need to consider the storage period or storage state of the ceramic sheets to be used, and excellent productivity It becomes.
[0039]
In the present embodiment, in order to obtain a small-sized and large-capacity capacitor, raw material particles constituting the ceramic sheet are those having an average particle size of 1.0 μm or less. Usually, the smaller the particle size of the raw material particles, the more difficult it is to improve the density of the ceramic sheet. The same applies to the first and second ceramic layers 11 and 12 that do not contain a plasticizer, and it is difficult to reduce the density difference between the two different thicknesses. However, by heating in the plasticizer diffusion step, not only the fluidity of the plasticizer but also the fluidity of the raw material particles can be improved. Therefore, when pressurization and heating are performed after the plasticizer diffusion step, the raw material particles move, and the density difference between the first ceramic layer 11 and the second ceramic layer 12 can be reduced to 0.1 g / cm ³ or less. It is easy to suppress the peeling of the second ceramic layer 12 due to the difference in shrinkage between the two.
[0040]
In this embodiment, benzyl butyl phthalate was used as the plasticizer, but in addition to this, a phthalic acid plasticizer having a low molecular weight such as dioctyl phthalate, dibutyl phthalate, benzyl dibutyl phthalate, benzyl octyl phthalate or the like was used. The same effect can be obtained. These phthalic acid-based plasticizers are excellent in compatibility with the resin (ethyl cellulose, acrylic resin, butyral resin, etc.) usually used in the metal paste that becomes the internal electrode 13, and the plasticizer easily moves inside the laminate. Integration of the second ceramic layer 12 and the first ceramic layer 11 is facilitated.
[0041]
Also, the multilayer ceramic capacitor has been described as an example. However, ceramics such as multilayer thermistors, multilayer inductors, multilayer varistors, and ceramic substrates in which ceramic layers and internal electrodes are alternately stacked and a ceramic layer is further provided on at least one of the upper and lower sides Similar effects can be obtained in parts.
[0042]
【The invention's effect】
As described above, according to the present invention, the plasticizer added to the internal electrode is diffused into the second ceramic layer, and the adhesion with the first ceramic layer is improved. Can be suppressed. As a result, a ceramic electronic component having excellent characteristics can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor according to a first embodiment of the present invention.
11 First ceramic layer 12 Second ceramic layer 13 Internal electrode 14 External electrode

Claims (7)

A laminate in which a plasticizer-free first ceramic layer and internal electrodes formed using a metal paste containing a plasticizer are alternately laminated, and a plasticizer-free second ceramic layer is laminated on the top and bottom. A first step of producing, a second step of heating and holding the laminate for a predetermined time to diffuse the plasticizer in the internal electrode into the second ceramic layer, and pressurization and heating of the laminate. A method for manufacturing a ceramic electronic component, comprising: a third step to be performed; and a fourth step of firing the laminate.   The method for manufacturing a ceramic electronic component according to claim 1, wherein the first and second ceramic layers have a network structure.   The method for producing a ceramic electronic component according to claim 1, wherein the plasticizer is a phthalic acid plasticizer.   The method for producing a ceramic electronic component according to claim 1, wherein the porosity of the first and second ceramic layers is 50% or more. The method for producing a ceramic electronic component according to claim 1, wherein the difference in density between the first ceramic layer and the second ceramic layer after the third step is 0.1 g / cm ³ or less. The method for manufacturing a ceramic electronic component according to claim 1, wherein the inorganic powder forming the second ceramic layer has a particle size of 1.0 μm or less. The method for producing a ceramic electronic component according to claim 1, wherein the plasticizer in the metal paste is 4 to 6 wt% of the metal component.

Images