JP2895141B2 - Manufacturing method of multilayer ceramic capacitor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic laminate element, in particular, a multilayer ceramic capacitor and a method of manufacturing the element.

[Conventional technology]

2. Description of the Related Art Conventionally, a ceramic laminate element in which ceramic films or thin plates and internal electrodes are alternately laminated, for example, a laminated ceramic capacitor, is usually manufactured by the following method.

First, the raw material composition is mixed and calcined, a suitable binder and a solvent are mixed with the calcined powder, and a thin film is formed using the mixture by a doctor blade method. A metal electrode is printed on this thin film and laminated. Every other metal electrode plate in this laminate is connected to an external electrode, and one system is positive and the other system is negative.

In this manufacturing method, as shown in FIG. 1, the area of the overlapping portion of the positive and negative electrode plates must be smaller than the total cross-sectional area. .

Since the capacitance of the capacitor is proportional to the electrode area, the above-mentioned capacitor cannot utilize the entire cross-sectional area of the ceramic thin film, which is an obstacle to miniaturization and large capacity of the capacitor. Also, depending on the type of ceramics, a relatively large strain is generated by the application of voltage, so stress concentrates near the boundary between the part with and without the electrode, and the ceramic is broken by prolonged or repeated voltage application. Or a failure such as peeling of the internal electrode may occur. Furthermore, in order to manufacture such a multilayer capacitor, it is necessary to increase the printing accuracy of the internal electrodes and the accuracy of the lamination position of each green sheet during lamination, which is an obstacle to improving the productivity.

As a method of solving the above-mentioned disadvantages, an example of a laminated electrostrictive effect element is used, and an electrophoresis method is used in JP-A-59-115579, with respect to an electrode exposed on a side end face of the element. There is disclosed a method for manufacturing an electrostrictive element, wherein an inorganic insulating layer is formed on the entire surface or every other layer. When such a manufacturing method is used, the above-mentioned disadvantages are eliminated. However, this method requires a high temperature to bake the inorganic insulating layer (often glassy) and is not economical. In addition, the inorganic insulating layer has a good compatibility with the ceramic body and thus has a wide range. Adheres to
Therefore, it is said that the distance between the electrodes must be 100 microns or more so that the insulating layers attached to the electrodes exposed on the side end surfaces do not continue with each other.
There is a disadvantage in that a capacitor having a high capacitance cannot be made with a capacitance of less than 100 microns.

[Problems to be solved by the invention]

In recent years, the demand for a multilayer ceramic capacitor having a small size and a large capacitance has been increasing. For this reason, while searching for ceramics having a high relative dielectric constant, efforts are being made to reduce the thickness of the ceramics even further.

In order to efficiently produce a multilayer capacitor having such a thin layer, it is necessary to develop a new electrode insulation method that does not have the disadvantages described in the above [Related Art].

[Means for solving the problem]

The present inventors have previously described the method for insulating a laminated electrostrictive element, but formed a coating layer by depositing polyamic acid by electrophoresis on the element end exposed portion of an internal electrode, and then heating the coating layer by heating. A method for imidizing a polyamic acid resin and forming an insulating layer with the obtained polyimide resin was previously filed (Japanese Patent Application No. 1-171854). The method according to the present application is epoch-making not only in that it has been conventionally difficult to solve the problem with an organic material, but also in that the thickness of one layer of the laminate can be reduced to 100 microns or less. Further, as an improved method of this method, a method of simultaneously depositing an insulating filler at the same time as depositing a polyamic acid on an exposed portion of an element end of an internal electrode has been proposed (Japanese Patent Application No. 1-294900).

The present inventors have discovered that the above method can be applied to the aforementioned multilayer ceramic capacitor, and have completed the present invention.

That is, the present invention provides: (1) a ceramic laminate in which the end faces of all the internal electrode plates are exposed at a specific side end face of a ceramic laminate in which ceramic films or thin plates and internal electrode plates are alternately laminated; The body has the general formula (II) (Wherein X is a phenyl group; a biphenyl group; and at least one of the phenyl group and the biphenyl group is O, CO, S, SO
₂ , a tetravalent group selected from the group consisting of a polyphenyl group linked by at least one of CH ₂ , C (CH ₃ ) ₂ and C (CF ₃ ) ₂ , wherein Y is a phenyl group; At least one of a phenyl group and a biphenyl group is O, CO,
A divalent group selected from the group consisting of a polyphenyl group bonded by at least one of S, SO ₂ , CH ₂ , C (CH ₃ ) ₂ and C (CF ₃ ) ₂ ; an alkylene group; and a xylylene group The carboxyl group of the polyamic acid resin having a repeating unit represented by the formula (1) is neutralized with a base, and immersed in an electrophoresis bath containing a film-forming agent obtained by dilution with water. The polyamic acid is deposited only on the exposed portion on the specific side end surface of the ceramic laminate of the internal electrode plate which is the anode and the vicinity thereof by performing electrophoresis using the internal electrode plate as an anode every other layer. A coating layer is formed and then heat-treated to imidize the polyamic acid resin of the coating layer to obtain a compound represented by the general formula (I) (Wherein, X and Y are as defined above), forming an insulating layer containing a polyimide resin having a repeating unit represented by the following formula: Electrophoresis is performed using the same electrophoresis bath as described above with the plate as the anode, and every other internal layer exposed on another side end surface different from the specific side end surface of the ceramic laminate is used. A multi-layer ceramic capacitor, wherein the polyamic acid is deposited only on the exposed portion of the electrode plate and in the vicinity thereof to form a coating layer, and then heat-treated to form an insulating layer containing the same polyimide resin as above. (2) The ceramic in which the end faces of all the internal electrode plates are exposed on the specific side end faces of the ceramic laminate in which the ceramic films or thin plates and the internal electrode plates are alternately laminated. Composites of the general formula (II) (Wherein X is a phenyl group; a biphenyl group; and at least one of the phenyl group and the biphenyl group is O, CO, S, SO
₂ , a tetravalent group selected from the group consisting of a polyphenyl group linked by at least one of CH ₂ , C (CH ₃ ) ₂ and C (CF ₃ ) ₂ , wherein Y is a phenyl group; At least one of a phenyl group and a biphenyl group is O, CO,
A divalent group selected from the group consisting of a polyphenyl group bonded by at least one of S, SO ₂ , CH ₂ , C (CH ₃ ) ₂ and C (CF ₃ ) ₂ ; an alkylene group; and a xylylene group The carboxyl group of the polyamic acid resin in a composition comprising a polyamic acid resin having a repeating unit represented by the formula and an insulating filler dispersed in the resin is neutralized with a base and diluted with water. Immerse in the obtained electrophoresis bath for film formation, perform electrophoresis using the internal electrode plate of the ceramic laminate every other layer as an anode, and perform the specific The polyamic acid and the insulating filler coated with the polyamic acid are deposited only on the exposed portion on the side end surface and in the vicinity thereof to form a coating layer, and then heat-treated to convert the polyamic acid resin of the coating layer into an imide. Conversion Not by the general formula (I) (Wherein X and Y are as defined above), forming an insulating layer composed of a polyimide resin having a repeating unit represented by the formula (1) and an insulating filler, and then forming a layer different from the internal electrode plate used as the anode. Electrophoresis was performed using the same internal electrode plate as an anode and using the same electrophoresis bath for forming a film as described above, and the ceramic laminate was exposed on another side end surface different from the specific side end surface. Is formed by depositing the polyamic acid and the insulating filler coated with the polyamic acid only on the exposed portion of the alternate internal electrode plate and in the vicinity thereof, to form a coating layer, and then heat-treat the same as above. A method of manufacturing a multilayer ceramic capacitor, characterized by forming an insulating layer comprising a polyimide resin and an insulating filler.

A part of the polyamic acid resin used in the production method of the present invention may be imidized in advance.

In the polyimide resin having the repeating unit represented by the general formula (I) and the polyamic acid resin having the repeating unit represented by the general formula (II), specific examples of X include the following: The following are specific examples of Y.

From the viewpoints of adhesion and heat resistance of the polyimide resin having the repeating unit represented by the general formula (I) to the ceramic laminate base, X is And Y is And the like.

The polyamic acid resin having a repeating unit represented by the general formula (II) used in the production method of the present invention is represented by the general formula (III) (Wherein X is as defined above) and a general formula (IV) H ₂ N—Y—NH ₂ (IV) (where Y is as defined above) Obtained by an addition reaction with diamines.

As the above tetracarboxylic anhydrides, for example,
Pyromellitic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 2,2', 3,3'-benzophenonetetracarboxylic dianhydride, 3,3 ', 4, 4'-biphenyltetracarboxylic dianhydride, 2,2 ', 3,3'-biphenyltetracarboxylic dianhydride, 2,2'-bis (3,4-
Dicarboxyphenyl) propane dianhydride, 2.2-bis (2,3-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride,
Bis (3,4-dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxylphenyl) methane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2, 5,6-naphthalenetetracarboxylic dianhydride,
1,2,3,4-benzenetetracarboxylic dianhydride, 3,4,9,1
Preferred are 0-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride and the like. Among these, particularly preferred tetracarboxylic dianhydrides are pyromellitic dianhydride, 3,3 ′,
4,4'-benzoenonetetracarboxylic dianhydride, 3,4
3 ', 4,4'-bisphenyltetracarboxylic dianhydride,
And bis (3,4-dicarboxyphenyl) ether dianhydride.

Examples of the above diamines include 3,3′-diaminobenzophenone, 1,3-bis (3-aminophenoxy) benzene, 4,4′-bis (3-aminophenoxy) biphenyl, and 2,2-bis [4- (3-aminophenoxy) phenyl] phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, bis [4- Meta-position diamines such as (3-aminophenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) phenyl] ketone, and bis [4- (3-aminophenoxy) phenyl] sulfone are exemplified. They may be used alone or as a mixture of two or more.

The reaction between the tetracarboxylic anhydride and the diamine is usually performed in an organic solvent. Examples of the organic solvent include N-methyl-2-pyrrolidone, N, N-dimedialacetamide, N, N-dimethylformamide, 1,3-dimethyl-2-imidazolidinone, N, N-diethylacetamide, N , N-dimethylmethoxyacetamide, dimethylsulfoxide, pyridine, dimethylsulfone, hexamethylphosphoramide, tetramethylurea, N-methylcaprolactam, tetrahydrofuran, m-dioxane, p
-Dioxane, 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, 1,2-bis (2-methoxyethoxy) ethane, bis [2- (2-methoxyethoxy)
Ethyl] ether and the like. These organic solvents may be used alone or in combination of two or more.

The reaction temperature is usually −20 ° C. or more and 200 ° C. or less, preferably −1
The room temperature is about 0 ° C. or more and 50 ° C. or less, more preferably about 0 ° C. or more.

 The reaction pressure is not particularly limited, and the reaction can be sufficiently performed at normal pressure.

The reaction time may vary depending on the type of the solvent, the reaction temperature and the diamine or acid dianhydride used.
Up to 40 hours, preferably about 4 to 24 hours, is sufficient.

The polyamic acid solution thus obtained is a solution containing about 5 to 40% by weight of polyamic acid, and has a logarithmic viscosity of 0.5 to 0.5%.
It is preferably about 4 dl / g (at 35 ° C., a temperature of 0.5 g / ml, measured with N, N-dimethylacetamide) because the water-solubility described later and the physical properties of the polyimide film after heat treatment are excellent.

In the present invention, an insulating filler can be added to the polyamic acid obtained as described above. As a method of addition, any method such as roll kneading and a ball mill may be used as long as the insulating filler is sufficiently dispersed in the polyamic acid. The addition amount of the insulating filler is preferably about 2 to 70% by volume. If the addition amount is too small, the effect of addition will not appear, and if it is too large, the insulating filler will precipitate in the final electrophoresis bath, which is not preferable.

The insulating filler used in the present invention has a resistivity of 10 ⁵ Ωcm
An inorganic compound or an organic compound may be used as long as it exhibits an electrical resistance of at least a certain level. Examples of the inorganic compound used as such an insulating filler include beryllium, magnesium, calcium, aluminum, boron, silicon, scandium, yttrium, lanthanum, titanium, zirconium, hafnium and rare earth oxides and composite oxides, aluminum and boron. , Silicon, titanium, zirconium, hafnium and other nitrides and oxynitrides, and carbides such as silicon carbide. Also, the organic compound must be one that does not dissolve in the electrophoresis bath,
Such materials include silicone resins, fluororesins represented by Teflon, phenolic resins, furan resins,
Epoxy resins, acrylic resins and the like are exemplified.

In the present invention, the shape of the insulating filler is particulate,
The size is arbitrary irrespective of the fibrous shape or the like, but the dimensions are determined in relation to the required thickness of the insulating layer film. That is,
It is necessary that the maximum diameter of the insulating filler is smaller than the minimum thickness of the insulating layer film. Furthermore, considering that it is important to keep a good dispersion state in an electrophoresis bath industrially,
The average diameter of the insulating filler is 20 microns or less, preferably
Desirably, it is 10 microns or less.

In the production method of the present invention, the polyamic acid resin having the repeating unit represented by the above general formula (II) can be prepared in the presence of water regardless of whether or not the insulating filler is dispersed in the polyamic acid solution. By the addition of a base, for example an amine or an alkali metal ion, the COOH group becomes COO
^- dissociate ions can or stable colloidal dispersion becomes soluble in water, which can be deposited on the internal electrode board exposed in the ceramic laminated body side end surface is an anode by electrophoresis, insolubilized it can.

Examples of the base include ammonia: secondary amines such as dialkylamine, diethanolamine, and morpholine: triethylamine, tributylamine, triethanolamine, triisopropanolamine, dimethylethanolamine, dimethylisopropanolamine, diethylethanolamine, dimethylbenzylamine, and the like. Tertiary amines: Inorganic bases such as caustic soda and caustic potash are used, but tertiary amines are particularly preferable in view of stability after dilution with water and properties of a coating film obtained.

The amount of the base necessary for imparting water dilutability is generally 30 to 110 mol%, particularly preferably 40 to 100 mol%, based on the carboxy equivalent of the polyamic acid to be neutralized. By performing the neutralization in this manner, the polyamic acid becomes completely water-soluble or partially solubilized to become a suspended state and becomes water-dilutable.

An electrophoretic bath for forming a film, comprising a suspension containing a polyamic acid capable of electrophoresis and / or an insulating filler coated with the polyamic acid by diluting the neutralized composition with water. It can be done.

The thus-precipitated polyamic acid resin or a coating layer composed of the polyamic acid resin and the insulating filler is subjected to a heat treatment to obtain the general formula (I) (Wherein, X is as defined above), or a polyimide resin having a repeating unit represented by the following formula (1) or an insulating layer composed of a polyimide resin and an insulating filler.

The polyimide resin obtained as described above, or the insulating layer composed of the polyimide resin and the insulating filler, has excellent dielectric strength and very good adhesion to metal.

The configuration of the multilayer ceramic capacitor according to the present invention,
As shown in FIGS. 2A and 2B, a ceramic film or thin plate and an internal electrode plate are alternately laminated, and the internal electrode plate is either above or below the ceramic film or thin plate. And the end faces of the inner electrode plate are exposed at the end face of the multilayer capacitor, and the end faces of the internal electrode plates have positive and negative polarities separately when the external electrodes are attached. Are insulated by the polyimide resin-containing insulating layer. To attach such a multilayer capacitor to a circuit, the external electrodes Ni, Sn
For example, plating can be applied directly, or a lead wire can be attached to an external electrode, and this lead wire can be used as a circuit.

Moreover, you may seal with a phenol resin etc. as needed.

All ceramics used for ceramic capacitors can be used for the multilayer ceramic capacitor of the present invention. Pb (Zn, Nb) O ₃ , Pb (F
e, W) O, Pb (Fe, Nb) O ₃ , Pb (Mg, Nb) O ₃ , Pb (Ni, W) O
₃ , Pb (Mg, W) O ₃ , PbTiO ₃ , Pb (Zr, Ti) O ₃ , Pb (Li, Fe,
_{W) O 3, (Pb 1} -x La x) (Zr y Ti 1-y) lead-based O _3, Perogusukaito compound or Pb ₅ Ge ₃ O lead-based compounds such as _11, BaTiO _3, Ba
(Ti, Sn) O ₃ , (Ba, Sr, Ca) TiO ₃ , (Ba, Ca) (Zr, Ti) O
₃ , barium-based perovskite compounds such as (Ba, Sr, Ca) (Zr, Ti) O ₃ , strontium-based perovskite compounds such as SrTiO ₃ , calcium-based perovskite compounds such as CaTiO ₃ and CaZrO ₃ , and Bi ₄ Ti ₃ O _{12 and the} like. Further, a mixture thereof may be used. Furthermore, the ceramic thin plate of the present invention includes natural and / or artificial mica.

Examples of the material for the internal electrode plate include conductive metal materials such as silver, palladium, gold, platinum, nickel, copper, and zinc, and alloys thereof.

In addition, the laminated body referred to in the present invention is not only a laminate made by the so-called green sheet method, but also a laminate obtained by laminating a sintered thin plate with an adhesive or the like, and a ceramic thin plate and an electrode alternately formed by CVD or PVD. Of course, stacks and the like are also included.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to examples.
Of course, the present invention is not limited to these examples.

Example 1 In a reaction vessel equipped with a stirrer, a reflux condenser and a nitrogen inlet tube, 53.0 g (0.25 mol) of 3,3'-diaminobenzophenone was dissolved in 240 ml of N, N-dimethylacetamide. To this solution was added powder of 78.6 g (0.244 mol) of 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride,
The mixture was stirred for 24 hours to obtain a polyamic acid solution. The logarithmic viscosity of the obtained polyamic acid was 0.6 dl / g. 23.9 g of dimethylethanolamine (55 mol% based on carboxyl equivalent) was gradually added to the polyamic acid solution, and the mixture was stirred at room temperature for 20 minutes. An aqueous acid solution was prepared (resin concentration 10% by weight).

In addition, a laminated body (one layer having a thickness of about 50 μm and 50 layers laminated, and the ceramic composition is Pb (Zn, Nb) O ₃ -Pb (Mg, Nb) O ₃ -BaTiO ₃
System, the relative dielectric constant is about 9,000, and the internal electrode is mainly made of an alloy of silver and palladium) .The metal electrode is exposed at every other end face, and the other end face is all metal. Those with exposed electrodes were made in advance.
Thus, a ceramic laminate in which the end faces of the metal electrodes are exposed on one side end face and the end faces of all the metal electrodes are exposed on the other side end face is produced, for example, as follows. I do.

First, when printing the electrode material on the green sheet, one coated with the electrode material on one entire surface (an “A” sheet, and the electrode is an “a” electrode), and one with a predetermined width near one side of one surface Two types of green sheets are produced, one in which the electrode material is applied to the remaining area without being applied to the area (the “B” sheet, and the electrode is the “b” electrode). These “A” and “B” sheets are alternately stacked, pressed and molded, degreased and sintered to form a ceramic laminate. The side end face of the ceramic laminate obtained in this way is “B”
There is no "B" sheet electrode on the side end surface ("P side surface") corresponding to one side where the sheet electrode material was not applied, only the "a" electrode applied to the "A" sheet Are exposed, so that the end faces of the metal electrodes are exposed every other layer. On the other hand, on the side end surfaces corresponding to all the remaining sides of the “B” sheet coated with the electrode material (of which the side end surface facing the “P side surface” is “Q side surface”), the “B” sheet is used. “B” electrode is also “a” on “A” sheet
Since the electrodes also exist, the end faces of all the metal electrodes are exposed.

A silver electrode (external electrode) was baked on the side end surface (“P side surface”) where the metal electrode (“a” electrode) was exposed every other layer, and a lead wire was connected to the external electrode by soldering. As a result, all the “a” electrodes are electrically connected to the lead wires.

The aqueous solution was put into a plastic bath to form an electrophoresis bath for film formation. The laminate was immersed in the bath, the lead wire was connected to an anode, and a voltage was applied at 60 V for 4 seconds to perform electrophoresis. . In that case, the side end surfaces where the end surfaces of all the metal electrodes are exposed (“Q side surface” and two side surfaces adjacent thereto)
In, the coating layer is formed only on the exposed portion of the “a” electrode connected to the anode and in the vicinity thereof, and the coating layer is not formed on the exposed portion of the “b” electrode not connected to the anode and in the vicinity thereof . After that, remove the laminate from the bath and wash it with water
The coating layer was subjected to a heat treatment at 150 ° C. for 2 hours and at 280 ° C. for 2 hours to dry imidize the coating layer. As a result, on the “Q side surface”, an insulating layer made of dry imide is formed only on the exposed portion of the “a” electrode and in the vicinity thereof, and the exposed portion of the “b” electrode is left exposed.

Next, the laminate is cut in the middle. Naturally, both the “a” electrode and the “b” electrode are exposed on this cut surface (referred to as “R side surface”). Therefore, a silver electrode (external electrode) was baked on the “Q side surface” where the imidized resin insulating layer was formed only on the “a” electrode portion, and a lead wire was connected to the external electrode with solder. As a result, all the “b” electrodes exposed on the “Q side” are electrically connected to the lead wires. At this time, the “a” electrode on the “Q side surface” is all insulated and thus insulated from the silver electrode. Therefore, the same electrophoresis was performed by using the same electrophoresis bath as above and connecting the lead wire to the anode. When that happens,
On the cut surface (“R side”) where the end faces of all metal electrodes are exposed, a coating layer is formed only on the exposed portion of the “b” electrode connected to the anode and in the vicinity thereof, and is not connected to the anode No coating layer is formed on the exposed portion of the “a” electrode and its vicinity. Therefore, when this laminate was heat-treated in the same manner as described above, an insulating layer of dry imide was formed only on the exposed portion of the “b” electrode on the “R side surface” and in the vicinity thereof, and the exposed portion of the “a” electrode was exposed. It will be left as it is. Therefore, if a silver electrode (external electrode) is baked on the "R side surface", only the exposed "a" electrode is connected to the external electrode.

The thickness of the insulating layer is about 50 microns and the dielectric strength is 50
It was confirmed that the voltage was 0 V or more.

Thus, a multilayer ceramic capacitor as shown in FIG. 2B was obtained. In FIG.
26 corresponds to the “R side”, and the “P side” at the beginning when the metal electrode (“a” electrode) is exposed every other layer.
Is attached to the other cut piece when the laminate is cut in the middle as described above, and is discarded together with the cut piece, so that it does not remain in the multilayer ceramic capacitor obtained by the method of the present invention. . Therefore, in the multilayer ceramic capacitor manufactured according to the present invention, a portion where the electrode plates do not overlap does not occur in the peripheral portion.

Example 2 In a reaction vessel equipped with a stirrer, reflux condenser and nitrogen inlet tube, 53.0 g (0.25 mol) of 3,3'-diaminobenzophenone was dissolved in 240 ml of N, N-dimethylacetamide. To this solution was added powder of 3,3 ′, 4,4 ′ (benzophenonetetracarboxylic dianhydride 78.6 g (0.244 mol)) and at 10 ° C.
The mixture was stirred for 24 hours to obtain a polyamic acid solution. 620 g of alumina powder (AKP-30 manufactured by Sumitomo Chemical Co., Ltd.) is added to this solution.
The resulting mixture was kneaded with three rolls to prepare an alumina-dispersed polyamic acid varnish. 21.7 g of dimethylethanolamine (relative to carboxy equivalent 50 mol%) was gradually added to the varnish, and the mixture was stirred at room temperature for 20 minutes.
3 g was gradually added at room temperature and diluted with water to prepare a polyamic acid suspension containing alumina powder.

Further, the same sample as in Example 1 was used as the sample of the laminate, and a silver electrode was baked on the side where the metal electrode was exposed every other layer, and a lead wire was connected with solder. Put the above suspension into a plastic tank, as an electrophoresis bath for film formation,
The laminate to be coated was used as an anode to infiltrate, and a lead wire was connected to the anode. Electrophoresis was performed by applying a voltage at 20 V for 5 seconds. Thereafter, the laminate was taken out, washed with an aqueous solution containing 20% by weight of N, N-dimethylacetamide, and then subjected to dry imidization by heat treatment at 150 ° C. for 2 hours and 280 ° C. for 2 hours. Next, the laminate was cut in the middle, a silver electrode was applied to the side where the imide resin insulating film was attached, and a lead wire was attached. By performing the same operation, a laminate having insulating layers on the left and right for each electrode was obtained. The thickness of this insulating layer was about 50 microns.

When the dielectric strength of the laminate thus obtained was measured, the voltage was 500 V or more.

Example 3 In a container equipped with a stirrer, a reflux condenser and a nitrogen inlet tube,
2,2-bis [4- (3-aminophenoxy) phenyl]
41.0 g (0.1 mol) of propane and 200 ml of N, N-dimethylacetamide were charged, cooled to around 0 ° C., and a powder of 21.8 g (0.1 mol) of pyromellitic dianhydride was added under a nitrogen atmosphere. The mixture was stirred at around ° C for 2 hours. Next, the solution was returned to room temperature and stirred under a nitrogen atmosphere for about 20 hours.
The logarithmic viscosity of the polyamic acid thus obtained was 1.5 dl / g. Triethylamine 2 in this polyamic acid solution
0.2 g (relative to carboxyl equivalent 100 mol%)
After stirring at room temperature for 97 hours, 973 g of water was gradually added with stirring to dilute to prepare a polyamic acid aqueous solution (resin concentration: 5% by weight).

A sample of the laminated body was prepared in the same manner as in Example 1, and an insulating layer was provided in the same manner as in Example 1 using this sample and the above-mentioned polyamic acid aqueous solution. This insulating layer has a thickness of 50μ and 50
It had a dielectric strength of 0 V or more.

Example 4 In a container equipped with a stirrer, a reflux condenser and a nitrogen inlet tube,
2,2-bis [4- (3-aminophenoxy) phenyl]
Add 41.0 g (0.1 mol) of propane and 219.6 g of N, N-dimethylacetamide, and add 3,3 ′, 4,4 ′ at room temperature under a nitrogen atmosphere.
Benzophenonetetracarboxylic dianhydride 31.6 g (0.0
(98 mol) as a dry solid, while paying careful attention to the rise in solution temperature, and reacted at room temperature for 23 hours. The logarithmic viscosity of the polyamic acid thus obtained was 0.70 dl / g.
14.6 g of triethanolamine in this polyamic acid solution
(Relative to carboxyl equivalent 50 mol%)
The mixture was stirred at 40 ° C., and 117.2 g of water was gradually added while stirring to dilute to prepare a polyamic acid aqueous solution (resin concentration: 15% by weight).

A sample of the laminated body was prepared in the same manner as in Example 1, and an insulating layer was provided in the same manner as in Example 1 using this sample and the above-mentioned polyamic acid aqueous solution. This insulating layer has a thickness of 50μ and 50
It had a dielectric strength of 0 V or more.

Example 5 Instead of alumina powder, use silica powder (average particle size 0.5 μm).
The experiment was performed in exactly the same manner as in Example 2 except that m) was used. The dielectric breakdown voltage of the sample was more than 500V.

Example 6 Instead of alumina powder, silicon nitride powder (average particle size 0.8
The experiment was carried out in exactly the same manner as in Example 2 except that μm) was used. The dielectric breakdown voltage of the sample was more than 500V.

Example 7 Instead of alumina powder, titania powder (average particle size 0.8
The experiment was carried out in exactly the same manner as in Example 2 except that μm) was used. The dielectric breakdown voltage of the sample was 500 V or more.

〔The invention's effect〕

As is clear from the above embodiment, the multilayer ceramic capacitor according to the present invention has a high dielectric strength, and can be manufactured more easily and efficiently than the conventional method, so that a multilayer ceramic capacitor having high reliability can be manufactured at low cost. It can be manufactured by

[Brief description of the drawings]

FIG. 1 is a sectional perspective view of a multilayer ceramic capacitor according to a conventional method which is currently commercially available. In FIG. 1, denotes a dielectric ceramic, denotes an internal electrode, and denotes an external electrode. FIG. 2A is a sectional perspective view of the multilayer ceramic capacitor according to the present invention. In FIG. 2A, denotes a dielectric ceramic, denotes an internal electrode, denotes a polyimide-containing insulating layer, and denotes a Q side surface or an R side surface. In this figure, the external electrodes on both sides of Q and R are omitted. FIG. 2B is a sectional view of the multilayer ceramic capacitor of the present invention. In FIG. 2B, denotes a dielectric ceramic, denotes an internal electrode, denotes a polyimide-containing insulating layer, denotes an external electrode, and denotes a Q side surface or an R side surface. In addition, the internal electrodes protruding on both sides of Q and R reach the side surfaces every other layer, and all the internal electrodes are covered with an insulating layer and insulated.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) H01G 4/12 H01G 4/232 H01G 4/30

Claims (2)

(57) [Claims] 1. A ceramic laminate in which the end faces of all the internal electrode plates are exposed at a specific side end face of a ceramic laminate in which ceramic films or thin plates and internal electrode plates are alternately laminated. Formula (II) (Wherein X is a phenyl group; a biphenyl group; and at least one of the phenyl group and the biphenyl group is O, CO, S, SO
₂ , a tetravalent group selected from the group consisting of a polyphenyl group linked by at least one of CH ₂ , C (CH ₃ ) ₂ and C (CF ₃ ) ₂ , wherein Y is a phenyl group; At least one of a phenyl group and a biphenyl group is O, CO,
A divalent group selected from the group consisting of a polyphenyl group bonded by at least one of S, SO ₂ , CH ₂ , C (CH ₃ ) ₂ and C (CF ₃ ) ₂ ; an alkylene group; and a xylylene group The carboxyl group of the polyamic acid resin having a repeating unit represented by the formula (1) is neutralized with a base, and immersed in an electrophoresis bath containing a film-forming agent obtained by dilution with water. The polyamic acid is deposited only on the exposed portion on the specific side end surface of the ceramic laminate of the internal electrode plate which is the anode and the vicinity thereof by performing electrophoresis using the internal electrode plate as an anode every other layer. A coating layer is formed and then heat-treated to imidize the polyamic acid resin of the coating layer to obtain a compound represented by the general formula (I) (Wherein, X and Y are as defined above), forming an insulating layer containing a polyimide resin having a repeating unit represented by the following formula: Electrophoresis is performed using the same electrophoresis bath as described above with the plate as the anode, and every other internal layer exposed on another side end surface different from the specific side end surface of the ceramic laminate is used. A multi-layer ceramic capacitor, wherein the polyamic acid is deposited only on the exposed portion of the electrode plate and in the vicinity thereof to form a coating layer, and then heat-treated to form an insulating layer containing the same polyimide resin as above. Manufacturing method. 2. A ceramic laminate in which the end faces of all the internal electrode plates are exposed at specific side end faces of a ceramic laminate in which ceramic films or thin plates and internal electrode plates are alternately laminated. Formula (II) (Wherein X is a phenyl group; a biphenyl group; and at least one of the phenyl group and the biphenyl group is O, CO, S, SO
₂ , a tetravalent group selected from the group consisting of a polyphenyl group linked by at least one of CH ₂ , C (CH ₃ ) ₂ and C (CF ₃ ) ₂ , a Y phenyl group; a biphenyl group; At least one of a phenyl group and a biphenyl group is O, CO,
A divalent group selected from the group consisting of a polyphenyl group bonded by at least one of S, SO ₂ , CH ₂ , C (CH ₃ ) ₂ and C (CF ₃ ) ₂ ; an alkylene group; and a xylylene group The carboxyl group of the polyamic acid resin in a composition comprising a polyamic acid resin having a repeating unit represented by the formula and an insulating filler dispersed in the resin is neutralized with a base and diluted with water. Immerse in the obtained electrophoresis bath for film formation, perform electrophoresis using the internal electrode plate of the ceramic laminate every other layer as an anode, and perform the specific The polyamic acid and the insulating filler coated with the polyamic acid are deposited only on the exposed portion on the side end surface and in the vicinity thereof to form a coating layer, and then heat-treated to convert the polyamic acid resin of the coating layer into an imide. Conversion Not by the general formula (I) (Wherein X and Y are as defined above), forming an insulating layer composed of a polyimide resin having a repeating unit represented by the formula (1) and an insulating filler, and then forming a layer different from the internal electrode plate used as the anode. Electrophoresis was performed using the same internal electrode plate as an anode and using the same electrophoresis bath for forming a film as described above, and the ceramic laminate was exposed on another side end surface different from the specific side end surface. Is formed by depositing the polyamic acid and the insulating filler coated with the polyamic acid only on the exposed portion of the alternate internal electrode plate and in the vicinity thereof, to form a coating layer, and then heat-treat the same as above. Forming an insulating layer comprising a polyimide resin and an insulating filler.