JP2001039773A - Production of ceramic slurry, ceramic green sheet and laminated ceramic electronic parts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently and uniformly disperse a ceramic powder without causing excess damage on the ceramic powder by mixing and crushing the ceramic powder having a specified average particle size and a dispersing medium by a medium-type dispersing method using dispersing media such as round stones and beads and then high-pressure dispersing the mixed and crushed slurry at a prescribed pressure. SOLUTION: A ceramic powder having an average particle size of 0.01 to 1 μm and a dispersing medium are mixed and crushed by a medium-type dispersing method and the obtained mixed and crushed slurry is high-pressure dispersed at a pressure of >=100 kg/cm2 (primary dispersion slurry). It is preferable to provide a secondary high-pressure dispersing process which comprises adding a binder to the primary dispersion slurry and further high-pressure dispersing the obtained slurry at a pressure of >=100 kg/cm2 to obtain a secondary dispersion slurry (final dispersion slurry). As the binder, a polyvinyl butyral resin, a cellulose resin, an acrylic resin, a polyvinyl acetate resin, or the like, can be used.

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 slurry and a ceramic green sheet used for manufacturing a multilayer ceramic electronic component, and a method for manufacturing a multilayer ceramic electronic component.

[0002]

2. Description of the Related Art A multilayer ceramic electronic component such as a multilayer ceramic capacitor or a ceramic multilayer substrate is usually manufactured through a process of laminating and pressing a ceramic green sheet, heat-treating and sintering a ceramic or an electrode.

For example, as shown in FIG. 1, an internal electrode 2 is provided in a ceramic element 1 and both ends of the ceramic element 1 are connected to internal electrodes 2 alternately drawn to different end faces. A pair of external electrodes 3 so as to be conductive
When manufacturing a multilayer ceramic capacitor having a structure in which a and 3b are provided, it is usually manufactured by the following method.

[0004] First, an electrode-arranged sheet 11 (FIG. 2) is formed by arranging internal electrodes for capacitance formation on the ceramic green sheet manufactured as described above. Next, as shown in FIG. 2, a predetermined number of electrode arrangement sheets 11 are laminated, and ceramic green sheets (outer layer sheets) 21 on which no electrodes are arranged on both upper and lower sides.
Are laminated and crimped to form a laminated body (laminated crimped body) in which one end side of each internal electrode 2 is alternately drawn to an end face on a different side. Then, after firing the laminated pressure-bonded body under predetermined conditions to sinter the ceramic, a conductive paste is applied to both ends of the fired laminated body (ceramic element) 1 (FIG. 1) and baked. External electrodes 3a and 3b (FIG. 1) that are electrically connected to the internal electrodes 2 are formed. Thereby, a multilayer ceramic capacitor as shown in FIG. 1 is obtained.

[0005] Other multilayer ceramic electronic components such as a multilayer ceramic multilayer substrate are also manufactured through a process of laminating ceramic green sheets.

In general, ceramic green sheets used in the production of multilayer ceramic electronic components are prepared by mixing a ceramic powder with a dispersion medium (solvent), a dispersant, a binder, a plasticizer, and the like at a predetermined ratio, and using a bead mill or a ball mill. A ceramic slurry produced by mixing and crushing using a medium-type disperser such as an attritor, a paint shaker, and a sand mill, is formed into a sheet of a predetermined thickness by a method such as a doctor blade method, and then dried. It is manufactured by.

However, in recent years, various multilayer ceramic electronic components such as multilayer ceramic capacitors have been reduced in size and size as in the case of other electronic elements.
Higher performance is required. For that purpose, it is necessary to reduce the thickness of the ceramic green sheet used for manufacturing the multilayer ceramic electronic component. In recent years, it has become necessary to use an extremely thin ceramic green sheet having a thickness of 10 μm or less.

As described above, in order to manufacture a ceramic green sheet having a small thickness, it is necessary to use, as a ceramic slurry used for manufacturing the ceramic green sheet, a slurry in which ceramic raw material powder is sufficiently dispersed. It is necessary to use a fine powder ceramic raw material having an average particle size of 0.01 to 1.0 μm as the ceramic raw material powder.

[0009]

However, the ceramic powder is blended with a dispersion medium (solvent), a dispersant, a binder, a plasticizer and the like at a predetermined ratio, and is mixed with a medium such as a bead mill, a ball mill, an attritor, a paint shaker, and a sand mill. It is difficult to sufficiently disperse a ceramic fine powder of 1.0 μm or less by a conventional method of producing a ceramic slurry in which mixing and crushing are performed using a mold disperser, and it is difficult to obtain a uniformly dispersed ceramic slurry. In fact, it is difficult to manufacture a high-quality ceramic green sheet that cannot be formed with a small thickness.

That is, the ceramic green sheet produced by using the ceramic slurry produced by the above-described conventional method has insufficient surface smoothness, cannot obtain a high density, and has insufficient tensile strength. In addition, there is a problem that the distribution of the resin such as the binder and the plasticizer becomes non-uniform, and the shrinkage ratio in the firing step after lamination varies from part to part, and sufficient dimensional accuracy cannot be obtained.
These problems become particularly remarkable when a binder having a high degree of polymerization is used.

In a conventional method for producing a ceramic slurry, a ball mill filled with a cobblestone or a bead mill filled with beads is used to improve the dispersibility by applying a forced collision or impact force to the ceramic powder. In some cases, the method of dispersing is used, but in that case, the crushing force due to collision or impact is too large, the damage to the ceramic powder is increased, the crystallinity of the ceramic powder is reduced, and the specific surface area is increased, There is a problem that a multilayer ceramic electronic component having desired electric characteristics cannot be obtained.

In some cases, a high-pressure dispersion method is used in which a slurry containing ceramic powder is pressurized at a high pressure and fluidized, and the ceramic powder is dispersed by collision or impact force. Since the crushing force is smaller than that of the method of forcible collision or impact force, such as the medium-type dispersion method, it is difficult to sufficiently crush the agglomerated aggregated particles. There is a problem that a ceramic slurry cannot be produced and a high quality ceramic green sheet cannot be obtained.

The present invention has been made in view of such a background, and can uniformly disperse a ceramic powder without excessively damaging the ceramic powder, and is used for manufacturing a ceramic electronic component. It is an object of the present invention to provide a method for producing a ceramic slurry capable of efficiently producing a ceramic slurry suitable for the above, and a method for producing a ceramic green sheet and a multilayer ceramic electronic component.

[0014]

In order to achieve the above object, a method of manufacturing a ceramic slurry according to the present invention (claim 1) is a method of manufacturing a ceramic slurry used for manufacturing a ceramic electronic component. 0.01
A mixing and crushing step of mixing and crushing a ceramic powder of about 1 μm and a dispersion medium by a medium-type dispersion method using a dispersion medium such as a cobblestone and beads to obtain a mixed and crushed slurry; And a high-pressure dispersing step of dispersing the ground slurry under high pressure at a pressure of 100 kg / cm ² or more to obtain a dispersed slurry.

A ceramic powder having an average particle size of 0.01 to 1 μm and a dispersion medium (solvent) are mixed and crushed by a medium-type dispersion method using a dispersion medium such as a cobblestone and beads to obtain a mixed and crushed slurry. After being obtained, the mixed / crushed slurry was
By performing high-pressure dispersion at a pressure of 0 kg / cm ² or more, a dispersed slurry in which ceramic powder is sufficiently dispersed can be obtained. That is, by dispersing the ceramic powder by combining the medium-type dispersion method and the high-pressure dispersion method, the crystallinity of the ceramic powder is impaired or the specific surface area is suppressed from becoming excessively large, and the ceramic powder is uniformly dispersed. It becomes possible to disperse and to produce a high quality ceramic slurry. In the present invention, it is possible to use a dispersion medium containing a dispersant, a plasticizer, and an antistatic agent,
It is also possible to use those containing other additives.

The high pressure dispersion in the present invention is as follows.
For example, a liquid to be dispersed pressurized to a high pressure may collide against a wall,
This is a broad concept meaning a method of dispersing a slurry by using a high-pressure dispersing device configured to perform dispersion by, for example, passing through a flow path having a tapered diameter gradually reduced.

Further, according to the present invention, the average particle size of ceramic powder (average primary particle size obtained by an electron microscope) is 0.0
It is particularly advantageous when it is in the range of 1 to 1 μm, but it is also possible to apply it when it exceeds the range of 0.01 to 1 μm.

Further, the method for producing a ceramic slurry according to claim 2 is characterized in that mixing and crushing are performed by the medium-type dispersion method in a state where a binder is added.

Even when the mixing / crushing step is carried out with the binder added, the ceramic powder can be dispersed uniformly without excessively damaging the ceramic powder. It becomes possible to produce a quality ceramic slurry. The binder may be previously mixed in the dispersion medium, or may be mixed when the ceramic powder is dispersed in the dispersion medium, and there is no particular restriction on the timing of the addition.

Further, according to the method for producing a ceramic slurry of the present invention (claim 3), there is provided a method for producing a ceramic slurry used for producing a ceramic electronic component, wherein the ceramic powder having an average particle size of 0.01 to 1 μm, And a dispersing medium containing no, a mixing and disintegrating step of mixing and disintegrating by a medium-type dispersing method using a dispersing medium such as a cobblestone and beads to obtain a disintegrating and disintegrating slurry; And a high-pressure dispersion step of obtaining a dispersion slurry by adding a binder to the mixture and performing high-pressure dispersion at a pressure of 100 kg / cm ² or more.

A binder is added to a mixed and crushed slurry obtained by mixing and crushing a ceramic powder and a dispersion medium containing no binder by a medium type dispersion method.
By performing high-pressure dispersion at a pressure of kg / cm ² or more, a dispersion slurry in which the ceramic powder is further dispersed can be obtained.

That is, the binder may be partially gelled and exist in the dispersion medium. In such a state, the binder is added rather than mixing and crushing the ceramic powder by the medium-type dispersion method. By mixing and crushing the ceramic powder and the dispersion medium by the medium-type dispersion method before performing, it is possible to improve the efficiency of mixing and crushing,
The dispersibility of the final ceramic powder can be further improved.

Further, according to the method for producing a ceramic slurry of the present invention (claim 4), there is provided a method for producing a ceramic slurry used for producing a ceramic electronic component, wherein the ceramic powder having an average particle size of 0.01 to 1 μm, And a dispersing medium containing no, a mixing and disintegrating step of mixing and disintegrating by a medium-type dispersing method using a dispersing medium such as a cobblestone and beads to obtain a disintegrating and disintegrating slurry; A high-pressure dispersion at a pressure of 100 kg / cm ² or more to obtain a primary dispersion slurry, adding a binder to the primary dispersion slurry, and further performing high-pressure dispersion at a pressure of 100 kg / cm ² or more. And a secondary high-pressure dispersion step of obtaining a secondary dispersion slurry (final dispersion slurry).

The mixed and crushed slurry obtained by mixing and crushing the ceramic powder and the dispersion medium containing no binder by the medium type dispersion method was obtained by high pressure dispersion at a pressure of 100 kg / cm ² or more. In the case where a binder is added to the primary dispersion slurry and further dispersed under high pressure at a pressure of 100 kg / cm ² or more, the ceramic powder can be uniformly dispersed without excessively damaging the ceramic powder, High quality ceramic slurry can be manufactured.

Further, according to the method for producing a ceramic slurry of the present invention (claim 5), there is provided a method for producing a ceramic slurry used for producing a ceramic electronic component, wherein the ceramic powder having an average particle size of 0.01 to 1 μm, And a dispersing medium containing no, a primary mixing and disintegrating step of mixing and disintegrating by a medium-type dispersing method using a dispersing medium such as a cobblestone and beads to obtain a primary mixing and disintegrating slurry; A secondary mixing / crushing step of adding a binder to the crushed slurry, mixing and crushing by a medium type dispersion method using a dispersion medium such as a boulder or beads to obtain a secondary mixing / crushed slurry, 100 kg / mixed / crushed slurry
a high-pressure dispersion step of obtaining a dispersion slurry by performing high-pressure dispersion at a pressure of ² cm or more.

A binder is added to a primary mixing / crushing slurry obtained by mixing / crushing a ceramic powder and a dispersion medium containing no binder by a medium type dispersion method.
Even when the secondary mixing / crushing slurry obtained by mixing / crushing by the medium type dispersion method is subjected to high pressure dispersion at a pressure of 100 kg / cm ² or more, excessive damage to the ceramic powder is caused. Without this, it becomes possible to uniformly disperse the ceramic powder and to produce a high-quality ceramic slurry.

[0027] The method for producing a ceramic slurry according to claim 6 is characterized in that a binder solution obtained by stirring and mixing a solvent and a binder and dispersing the mixture under a high pressure of 100 kg / cm ² or more is used as the binder. .

By using a binder solution obtained by stirring and mixing a solvent and a binder and dispersing the mixture under high pressure at a pressure of 100 kg / cm ² or more, it is possible to suppress the generation of a gel which is generated when the binder is directly added. This makes it possible to further improve the dispersibility of the ceramic powder.

Further, in the method for producing a ceramic slurry according to claim 7, a binder mixed solution obtained by stirring and mixing a solvent and a binder is used at 40 to 100 ° C.
Characterized in that a binder solution heated and refluxed in step (1) is used.

When a binder solution obtained by heating and refluxing a binder mixed solution obtained by stirring and mixing a solvent and a binder at 40 to 100 ° C. is used as the binder, a state in which the binder is more reliably dissolved (μm size) is used. (Without aggregation) can be added, and the dispersibility of the ceramic powder can be further improved.

Further, the method of manufacturing a ceramic slurry according to claim 8 is characterized in that the viscosity of the dispersion slurry (final dispersion slurry) is 0.01 to 0.1 Pas.

When the viscosity of the dispersion slurry (final dispersion slurry) is adjusted to 0.01 to 0.1 Pas, a ceramic slurry suitable for use in the step of producing a ceramic green sheet formed into a sheet is obtained. And the present invention can be made more effective.

In the method for producing a ceramic slurry according to a ninth aspect, the medium-type dispersion method is a method using a ball mill or a bead mill.

When a method using a ball mill or a bead mill is applied as the medium-type dispersion method, the aggregated particles of the ceramic can be reliably disintegrated, and the present invention can be made effective. In the present invention, in addition to the ball mill and the bead mill described above, for example, a method using a medium-type disperser such as an attritor, a paint shaker, and a sand mill can be applied.

The method for manufacturing a ceramic green sheet according to the present invention (Claim 10) is the same as that of the present invention (Claims 1 to 5).
The ceramic slurry produced by the method of 9) is formed into a sheet on a predetermined base material, and has a thickness of 0.1 to 10
It is characterized by forming a ceramic green sheet of μm.

The ceramic slurry produced by the method according to any one of claims 1 to 9 has an average particle size of 0.01 to 1 μm.
m of the ceramic powder is sufficiently dispersed in the dispersion medium, and is formed into a sheet to have a small thickness (0.
1 to 10 μm), making it possible to reliably produce high-quality ceramic green sheets. In other words, it has excellent surface smoothness, high density, high tensile strength, and
It is possible to obtain a ceramic green sheet suitable for use in manufacturing a multilayer ceramic electronic component, in which the distribution of a resin such as a binder and a plasticizer is uniform. When a multilayer ceramic electronic component is manufactured using the ceramic green sheets, a high-quality and highly reliable multilayer ceramic electronic component having desired characteristics can be obtained.

The method for manufacturing a multilayer ceramic electronic component of the present invention (Claim 11) is the same as that of the invention (Claims 1 to 1).
A ceramic green sheet is formed using the ceramic slurry produced by the method 9), and the ceramic green sheet is laminated with a base metal internal electrode, cut and fired, and then an external electrode is formed.

A ceramic green sheet is formed using the ceramic slurry produced by the method of the present invention, and the ceramic green sheet is laminated, cut, and fired with a base metal internal electrode, and then an external electrode is formed. It is possible to obtain a high-quality and highly reliable multilayer ceramic electronic component having characteristics.

[0039]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be shown and the features thereof will be described in more detail. In practicing the present invention, there are no particular restrictions on the type and specific composition of the ceramic powder, and dielectric ceramic powders such as barium titanate, strontium titanate, and lead titanate, and magnetic materials such as ferrites The present invention can be widely applied to ceramic slurries using various ceramic powders such as body ceramic powder, piezoelectric ceramic powder, and insulator ceramic powder such as alumina and silica.

Further, regarding the particle size of the ceramic powder,
Basically, it can be applied without any problem as long as it has a diameter passing through a high-pressure dispersing apparatus, but it is difficult to disperse by a conventional dispersing method. The average particle diameter obtained by an electron microscope is 0.01 to 1 μm.
When applied to ceramic powders, the effects of the present invention are most exhibited.

Further, the ceramic powder may contain additives and impurities. For example, when the ceramic powder contains barium titanate as a main component, glass, magnesium oxide, manganese oxide, barium oxide, a rare earth oxide, a calcium oxide component, or the like may be contained as an additive.

In the present invention, there is no particular limitation on the type of dispersion medium (solvent). For example, aromatic solvents such as toluene and xylene and alcohols such as ethyl alcohol, isopropyl alcohol and butyl alcohol are used. A dispersion medium (solvent) can be used, and one of these may be used alone or as a mixture. Further, as the dispersion medium, another organic solvent can be used, and water can be used.

Preferred examples of the dispersant usable in the present invention include anionic dispersants such as carboxylate, sulfonate and phosphate. Further, a more preferable example is a polycarboxylic acid type containing no metal ion. There is no particular limitation on the dispersant, and various other dispersants can be used.

As the binder, a polyvinyl butyral resin, a cellulose resin, an acrylic resin, a vinyl acetate resin, or the like can be used, and the type and amount of the binder are appropriately determined according to the intended ceramic green sheet. Selected.

As the plasticizer, various plasticizers such as polyethylene glycol and phthalic acid ester are appropriately used. Further, the amount is selected according to the target ceramic green sheet.

The above-mentioned various conditions for the additives such as the ceramic powder, the dispersion medium, the dispersant, the plasticizer and the like apply to all the claims of the present application.

Example 1 100 parts by weight of a commercially available dielectric material having a particle size of 0.2 μm (here, barium titanate-based ceramic powder) was used.
2 parts by weight of an anionic dispersant, 80 parts by weight of a 10% by weight solution of an acrylic resin-based binder as a binder, 1.4 parts by weight of dioctyl phthalate (hereinafter referred to as “DOP”) which is a phthalate as a plasticizer, and a dispersion medium (solvent) ) Were mixed with 50 parts by weight of toluene and 50 parts by weight of ethanol, respectively.
0 parts by weight are added. Next, the compounded slurry is mixed and crushed by a ball mill for 5 hours. Then, the mixed and crushed slurry mixed and crushed by a ball mill is subjected to a pressure of 1300 kg / c by a high-pressure dispersion device.
Processing is performed 20 times at m ² and a processing rate of 300 cc / min to obtain a dispersion slurry (final dispersion slurry) for producing a ceramic green sheet.

Then, the dispersibility of the dispersion slurry thus obtained was evaluated by a particle size distribution analyzer manufactured by Microtrac. As a result, the integrated 90% particle size (D90) of the particle size distribution was 0.45 μm. Further, after the dispersion slurry was dried and heated to 500 ° C. to remove the binder, the specific surface area was measured. As a result, the rate of increase with respect to the original specific surface area was 8%.

Next, the dispersion slurry was formed into a sheet by a doctor blade method to produce a ceramic green sheet. Then, the surface roughness (Ra) of the produced ceramic green sheet was measured with an atomic force microscope, and further, as a density ratio of the ceramic green sheet,
The ratio between the measured density and the theoretical density (measured density / theoretical density) was determined. As a result, Ra was 60 nm and the density ratio was 1.00.

Next, using this ceramic green sheet, as shown in FIG. 1, an internal electrode 2 is provided in a ceramic element 1 and both ends of the ceramic element 1 are alternately provided on different sides. A multilayer ceramic capacitor having a structure in which a pair of external electrodes 3a and 3b are provided so as to be electrically connected to the internal electrode 2 drawn out to the end face was manufactured.

The method for manufacturing the multilayer ceramic capacitor is as follows. First, a Ni paste is screen-printed on the ceramic green sheet produced as described above to form an electrode-arranged sheet on which internal electrodes for capacitance formation are arranged. Next, as shown in FIG. 2, a predetermined number (here, 70 layers) of electrode arrangement sheets 11 are laminated, and ceramic green sheets (outer layer sheets) 21 on which electrodes are not arranged are provided on the upper and lower surfaces. By laminating and crimping, a laminated body (laminated crimped body) is formed in which one end side of each internal electrode 2 is alternately drawn to an end surface on a different side. Then, after the laminated pressure-bonded body is cut into a predetermined size by a dicer, binder removal and firing are performed. The binder is removed by heat treatment in a nitrogen atmosphere. The firing is performed by heating to a predetermined temperature in a weak reducing atmosphere. Then, a conductive paste containing silver as a conductive component is applied to both ends of the fired laminate (ceramic element) 1 and baked, so that the external electrodes 3 electrically connected to the internal electrodes 2 are formed.
a, 3b (FIG. 1) are formed. Thus, a multilayer ceramic capacitor having Ni as the internal electrode 2 as shown in FIG. 1 is obtained.

The short-circuit rate (short-circuit occurrence rate) of the multilayer ceramic capacitor manufactured as described above was measured and found to be as good as 3.0%. The temperature characteristics of the capacitance satisfied X7R.

Example 2 First, 2 parts by weight of an anionic dispersant, toluene and ethanol were added to 100 parts by weight of a commercially available dielectric material having a particle size of 0.2 μm (here, barium titanate-based ceramic powder). In addition to 35 parts by weight of each, 500 parts by weight of zirconia cobblestone having a diameter of 2 mm are added. Next, the compounded slurry is mixed and crushed by a ball mill for 5 hours. Thereafter, the mixed and crushed slurry mixed and crushed by a ball mill is taken out, and 10 parts by weight of an acrylic resin-based binder as a binder and DO as a plasticizer are previously added thereto.
A binder solution prepared by stirring and dissolving 1.4 parts by weight of P and 35 parts by weight of each of toluene and ethanol as a solvent is added. Then, the pressure was 1300 kg / c
The treatment is performed 15 times at m ² and a treatment amount of 300 cc / min to obtain a dispersion slurry (final dispersion slurry) for producing a ceramic green sheet.

The dispersibility of the dispersion slurry thus obtained was evaluated using a particle size distribution analyzer manufactured by Microtrac. As a result, D90 was 0.45 μm. Further, after the dispersion slurry was dried and heated to 500 ° C. to remove the binder, the specific surface area was measured. As a result, the rate of increase with respect to the original specific surface area was 8%.

Next, this dispersed slurry was formed into a sheet by a doctor blade method to produce a ceramic green sheet. Then, the surface roughness (Ra) of the produced ceramic green sheet was measured with an atomic force microscope, and further, as a density ratio of the ceramic green sheet,
The ratio between the measured density and the theoretical density (measured density / theoretical density) was determined. As a result, Ra was 60 nm and the density ratio was 1.00.

Next, a multilayer ceramic capacitor was manufactured using the ceramic green sheets. The manufacturing method of the multilayer ceramic capacitor is the same as that of the first embodiment, and therefore the description is omitted to avoid duplication. The short-circuit rate of the manufactured multilayer ceramic capacitor was measured and found to be as good as 3.0%. The temperature characteristics of the capacitance satisfied X7R.

Example 3 First, 2 parts by weight of an anionic dispersant, 35 parts each of toluene and ethanol were added to 100 parts by weight of a commercially available dielectric material having a particle size of 0.2 μm (here, barium titanate-based ceramic powder). Parts by weight and 500 parts by weight of zirconia cobblestone having a diameter of 2 mm are added. Then, the compounded slurry is mixed and crushed by a ball mill for 5 hours. Thereafter, the mixed and crushed slurry mixed and crushed by a ball mill is taken out, and the pressure is 1300 kg by a high-pressure dispersion device.
A dispersion slurry (primary dispersion slurry) is obtained by treating 10 times / cm ^{2 at} a treatment rate of 300 cc / min. Next, 10 parts by weight of an acrylic resin-based binder as a binder, 1.4 parts by weight of DOP as a plasticizer, and 35 parts by weight of toluene and ethanol as solvents were mixed and dissolved in the primary dispersion slurry in advance. Add the saved binder solution. Then, further, by a high-pressure dispersion device, a pressure of 130
The slurry is treated 5 times at 0 kg / cm ^{2 at} a treatment rate of 300 cc / min to obtain a secondary dispersion slurry (final dispersion slurry) for producing a ceramic green sheet.

The dispersibility of the final dispersion slurry thus obtained was evaluated using a particle size distribution analyzer manufactured by Microtrac. As a result, D90 was 0.42 μm. Further, the final dispersion slurry is dried, and
After heating to ° C. to remove the binder, the specific surface area was measured, and the rate of increase relative to the original specific surface area was 8%.

Next, the dispersion slurry was formed into a sheet by a doctor blade method to produce a ceramic green sheet. Then, the surface roughness (Ra) of the produced ceramic green sheet was measured with an atomic force microscope, and further, as a density ratio of the ceramic green sheet,
The ratio between the measured density and the theoretical density (measured density / theoretical density) was determined. As a result, Ra was 55 nm and the density ratio was 1.00.

Next, a multilayer ceramic capacitor was manufactured using the ceramic green sheets. The manufacturing method of the multilayer ceramic capacitor is the same as that of the first embodiment, and therefore the description is omitted to avoid duplication. As a result of measuring the short-circuit rate of the obtained multilayer ceramic capacitor, it was as good as 3.0%. The temperature characteristics of the capacitance satisfied X7R.

Example 4 First, 2 parts by weight of an anionic dispersant, 35 parts each of toluene and ethanol were added to 100 parts by weight of a commercially available dielectric material having a particle size of 0.2 μm (here, barium titanate-based ceramic powder). Parts by weight and 500 parts by weight of zirconia cobblestone having a diameter of 2 mm are added. Then, the compounded slurry is mixed and crushed by a ball mill for 5 hours. Thereafter, the mixed and crushed slurry mixed and crushed by a ball mill is taken out, and the pressure is 1300 kg by a high-pressure dispersion device.
A dispersion slurry (primary dispersion slurry) is obtained by treating 10 times / cm ^{2 at} a treatment rate of 300 cc / min. Next, 10 parts by weight of an acrylic resin-based binder as a binder, 1.4 parts by weight of DOP as a plasticizer, and 35 parts by weight of toluene and ethanol as a solvent were combined and dissolved in the primary dispersion slurry with stirring. A binder solution prepared by heating and refluxing at 5 ° C. for 5 hours is added. Then, further, by a high-pressure dispersion device, a pressure of 130
The slurry is treated 5 times at 0 kg / cm ^{2 at} a treatment rate of 300 cc / min to obtain a secondary dispersion slurry (final dispersion slurry) for producing a ceramic green sheet.

The dispersibility of the final dispersion slurry thus obtained was evaluated using a particle size distribution analyzer manufactured by Microtrac. As a result, D90 was 0.42 μm.
The final dispersion slurry was dried, heated to 500 ° C. to remove the binder, and the specific surface area was measured. As a result, the rate of increase relative to the original specific surface area was 8%.

Next, the final dispersion slurry was formed into a sheet shape by a doctor blade method to produce a ceramic green sheet. Then, the surface roughness (Ra) of the produced ceramic green sheet was measured by an atomic force microscope, and the ratio of the measured density to the theoretical density (actual density / theoretical density) was determined as the density ratio of the ceramic green sheet. As a result, Ra was 55 nm and the density ratio was 1.00.
Met.

Next, a multilayer ceramic capacitor was manufactured using the ceramic green sheets. The manufacturing method of the multilayer ceramic capacitor is the same as that of the first embodiment, and therefore the description is omitted to avoid duplication. As a result of measuring the short-circuit rate of the obtained multilayer ceramic capacitor, it was as good as 1.5%. The temperature characteristics of the capacitance satisfied X7R.

Example 5 First, 2 parts by weight of an anionic dispersant, 35 parts each of toluene and ethanol were added to 100 parts by weight of a commercially available dielectric material having a particle size of 0.2 μm (here, barium titanate-based ceramic powder). Parts by weight and 500 parts by weight of zirconia cobblestone having a diameter of 2 mm are added. Then, this slurry is mixed and crushed by a ball mill for 5 hours. Thereafter, the mixed and crushed slurry mixed and crushed by a ball mill is taken out, and the pressure is 1300 kg by a high-pressure dispersion device.
A dispersion slurry (primary dispersion slurry) is obtained by treating 10 times / cm ^{2 at} a treatment rate of 300 cc / min. Next, 10 parts by weight of an acrylic resin-based binder as a binder, 1.4 parts by weight of DOP as a plasticizer, and 35 parts by weight of toluene and ethanol each as a solvent were mixed and dissolved in the primary dispersion slurry in advance. A binder solution prepared by treating five times with a high-pressure disperser at a pressure of 1000 kg / cm ² and a throughput of 300 cc / min is added. Then, further, by a high-pressure dispersion device, a pressure of 130
The slurry is treated 5 times at 0 kg / cm ^{2 at} a treatment rate of 300 cc / min to obtain a secondary dispersion slurry (final dispersion slurry) for producing a ceramic green sheet.

The dispersibility of the final dispersion slurry thus obtained was evaluated using a particle size distribution analyzer manufactured by Microtrac. As a result, D90 was 0.42 μm.
The final dispersion slurry was dried, heated to 500 ° C. to remove the binder, and the specific surface area was measured. As a result, the rate of increase relative to the original specific surface area was 8%.

Next, the final dispersion slurry was formed into a sheet by a doctor blade method to produce a ceramic green sheet. Then, the surface roughness (Ra) of the produced ceramic green sheet was measured by an atomic force microscope, and the ratio of the measured density to the theoretical density (actual density / theoretical density) was determined as the density ratio of the ceramic green sheet. As a result, Ra was 55 nm and the density ratio was 1.00.
Met.

Next, a multilayer ceramic capacitor was manufactured using the ceramic green sheets. The manufacturing method of the multilayer ceramic capacitor is the same as that of the first embodiment, and therefore the description is omitted to avoid duplication. As a result of measuring the short-circuit rate of the obtained multilayer ceramic capacitor, it was as good as 0.5%. The temperature characteristics of the capacitance satisfied X7R.

Example 6 A dispersion slurry was produced under the same conditions as in Example 1 except that the binder was changed to polyvinyl butyral, and a ceramic green sheet was produced from the dispersion slurry. The dispersibility of the dispersion slurry produced in this example was evaluated using a particle size distribution analyzer manufactured by Microtrac. As a result, D9
0 was 0.45 μm. Also, after drying this dispersion slurry and heating to 500 ° C. to remove the binder,
When the specific surface area was measured, the rate of increase with respect to the original specific surface area was 8%.

Next, the dispersed slurry of this embodiment was formed into a sheet by a doctor blade method to produce a ceramic green sheet. Then, the surface roughness (Ra) of the produced ceramic green sheet was measured by an atomic force microscope, and the ratio of the measured density to the theoretical density (actual density / theoretical density) was determined as the density ratio of the ceramic green sheet. As a result, Ra was 60 nm and the density ratio was 1.00.

Next, a multilayer ceramic capacitor was manufactured using the ceramic green sheets. The manufacturing method of the multilayer ceramic capacitor is the same as that of the first embodiment, and therefore the description is omitted to avoid duplication. As a result of measuring the short-circuit rate of the obtained multilayer ceramic capacitor, it was as good as 3.0%. The temperature characteristics of the capacitance satisfied X7R.

[Comparative Example 1] A dispersion slurry was prepared and dispersed under the same conditions as in Example 1 except that the disperser was changed from a high-pressure disperser used in Examples 1 to 6 to a sand mill. A ceramic green sheet was prepared from the slurry. The dispersibility of the dispersion slurry produced by the method of this comparative example was evaluated by a particle size distribution analyzer manufactured by Microtrac. As a result, D90 was 0.60 μm. Further, after drying this dispersion slurry and heating it to 500 ° C. to remove the binder, the specific surface area was measured. As a result, the rate of increase with respect to the original specific surface area was 30%.

Next, the dispersion slurry of this comparative example was formed into a sheet by a doctor blade method to produce a ceramic green sheet. Then, the surface roughness (Ra) of the obtained ceramic green sheet was measured with an atomic force microscope, and the ratio of the measured density to the theoretical density (actual density / theoretical density) was determined as the density ratio of the ceramic green sheet. . As a result, Ra was 110 nm and the density ratio was 0.80.

Next, a multilayer ceramic capacitor was manufactured using the ceramic green sheets. The manufacturing method of the multilayer ceramic capacitor is the same as that of the first embodiment, and therefore the description is omitted to avoid duplication. As a result of measuring the short-circuit rate of the obtained multilayer ceramic capacitor, the short-circuit rate was as high as 50%. Further, the temperature characteristics of the capacitance did not satisfy X7R.

[Comparative Example 2] The pressure at which the slurry was dispersed by the high-pressure disperser was 1300 kg / cm ² to 50 kg / cm ^2.
Except for changing to above, a dispersion slurry was produced under the same conditions as in Example 1 above, and a ceramic green sheet was produced from the dispersion slurry. The dispersibility of the dispersion slurry produced by the method of this comparative example was evaluated by a particle size distribution analyzer manufactured by Microtrac. As a result, D90
Was 0.60 μm. Further, the dispersion slurry was dried, heated to 500 ° C. to remove the binder, and the specific surface area was measured. As a result, the rate of increase with respect to the original specific surface area was 7%.

Next, the dispersion slurry of this embodiment was formed into a sheet by a doctor blade method to produce a ceramic green sheet. Then, the surface roughness (Ra) of the obtained ceramic green sheet was measured with an atomic force microscope, and the ratio of the measured density to the theoretical density (actual density / theoretical density) was determined as the density ratio of the ceramic green sheet. . As a result, Ra was 110 nm and the density ratio was 0.80.

Next, a multilayer ceramic capacitor was manufactured using the ceramic green sheets. The manufacturing method of the multilayer ceramic capacitor is the same as that of the first embodiment, and therefore the description is omitted to avoid duplication. When the short-circuit rate of the obtained multilayer ceramic capacitor was measured, the short-circuit rate was as high as 45%. The temperature characteristics of the capacitance satisfied X7R.

The dispersibility of the dispersion slurries (final dispersion slurries) obtained in Examples 1 to 6 and Comparative Examples 1 and 2, the specific surface area after debinding, the surface roughness of the produced ceramic green sheet, and the density ratio Table 1 summarizes data on the short-circuit rate and the temperature characteristics of the capacitance of the multilayer ceramic capacitor manufactured using the ceramic green sheets.

[0079]

[Table 1]

The present invention is not limited to the above-described embodiments and examples, but includes the type of ceramic powder and dispersion medium, the type of medium-type dispersion method, and the type of high-pressure dispersion used for high-pressure dispersion. With regard to the specific configuration of the dispersing device, and the types and amounts of additives such as dispersants, plasticizers and antistatic agents, various applications and modifications can be made within the scope of the invention.

[0081]

As described above, the method for producing a ceramic slurry according to the present invention (claim 1) has an average particle size of 0.01.
A mixed and crushed slurry obtained by mixing and crushing a ceramic powder of about 1 μm and a dispersion medium (solvent) by a medium-type dispersion method using a dispersion medium such as a cobblestone and beads is 100 kg / cm.
High-pressure dispersion is performed at a pressure of ² or more, and since the ceramic powder is dispersed by combining the medium-type dispersion method and the high-pressure dispersion method, as in the case of performing dispersion only by the medium-type dispersion method, It is possible to prevent the crystallinity of the ceramic powder from being impaired or to prevent the specific surface area from becoming excessively large, and to prevent insufficient disintegration of the aggregated particles as in the case of only high-pressure dispersion. Thus, the ceramic powder can be uniformly dispersed without excessively damaging the ceramic powder, and a high-quality ceramic slurry can be efficiently produced. That is, according to the method for producing a ceramic slurry of the present invention, particles set by the medium-type dispersion method are efficiently crushed, and an ideal slurry dispersion design that avoids excessive pulverization by high-pressure dispersion becomes possible. Also,
Ceramic green sheets manufactured using such a ceramic slurry having good dispersibility have high density and excellent surface smoothness, so when a multilayer ceramic electronic component is manufactured using the ceramic green sheets, It is possible to reduce the short-circuit rate and improve the reliability. Further, since the damage to the ceramic powder is small, the reproducibility of desired characteristics can be improved.

Further, as in the method for producing a ceramic slurry according to the second aspect, mixing and mixing are performed with the binder added.
Even when the crushing step is performed, the ceramic powder can be uniformly dispersed without excessively damaging the ceramic powder, and a high-quality ceramic slurry can be manufactured. .

Further, as in the method for producing a ceramic slurry of the present invention (claim 3), a ceramic powder and a dispersion medium containing no binder are mixed and crushed by a medium-type dispersion method. Even when a binder is added to the mixed / crushed slurry and the mixture is dispersed under high pressure at a pressure of 100 kg / cm ² or more, a dispersed slurry in which the ceramic powder is further dispersed can be obtained.

That is, the binder may be partially gelled and exist in the dispersion medium. In such a state, the binder is added rather than mixing and pulverizing the ceramic powder by the medium-type dispersion method. By mixing and crushing the ceramic powder and the dispersion medium by the medium-type dispersion method before performing, it is possible to improve the efficiency of mixing and crushing,
The dispersibility of the final ceramic powder can be further improved.

Further, as in the method for producing a ceramic slurry according to claim 4, a mixed / crushed slurry obtained by mixing / crushing a ceramic powder and a dispersion medium containing no binder by a medium type dispersion method is used. When a binder is added to the primary dispersion slurry obtained by high-pressure dispersion at a pressure of 100 kg / cm ² or more, and the high-pressure dispersion is further performed at a pressure of 100 kg / cm ² or more, excessive damage to the ceramic powder may occur. In addition, the ceramic powder can be uniformly dispersed, and a high-quality ceramic slurry can be manufactured.

Further, as in the method for manufacturing a ceramic slurry according to claim 5, a ceramic powder and a dispersion medium containing no binder are mixed and crushed by a medium type dispersion method to form a primary mixed / crushed slurry. Even when the secondary mixing / crushing slurry obtained by adding a binder and mixing / crushing again by the medium-type dispersion method is subjected to high pressure dispersion at a pressure of 100 kg / cm ² or more, the ceramic is also used. The ceramic powder can be uniformly dispersed without excessively damaging the powder, and a high-quality ceramic slurry can be manufactured.

Further, as in the method for producing a ceramic slurry according to claim 6, when a binder solution obtained by stirring and mixing a solvent and a binder and dispersing the mixture under a high pressure of 100 kg / cm ² or more is used as the binder. In addition, it is possible to suppress and prevent the generation of a gel which is generated when the binder is directly added, and to further improve the dispersibility of the ceramic powder.

Further, as in the method for producing a ceramic slurry according to claim 7, a binder mixed solution obtained by stirring and mixing a solvent and a binder is used as a binder.
When using a binder solution heated and refluxed at ℃, it becomes possible to add the binder in a state where the binder is more reliably dissolved (without agglomeration of μm size),
Further, the dispersibility of the ceramic powder can be improved.

In the case where the viscosity of the dispersion slurry (final dispersion slurry) is set to 0.01 to 0.1 Pas as in the method for producing a ceramic slurry according to claim 8, the ceramic green sheet is formed into a sheet shape. It is possible to obtain a ceramic slurry suitable for use in the step of producing a sapphire, and to further make the present invention more effective.

Further, when a method using a ball mill or a bead mill is applied as a medium-type dispersion method as in the method for producing a ceramic slurry according to the ninth aspect, the aggregated ceramic particles can be reliably crushed. That is, the present invention can be made effective.

The method for manufacturing a ceramic green sheet according to the present invention (Claim 10) is the same as that of the present invention (Claims 1 to 5).
The average particle size produced by the method of 9) is 0.01 to 1
Since a ceramic slurry in which μm ceramic powder is sufficiently dispersed in a dispersion medium is formed into a sheet on a predetermined base material, a ceramic green sheet having a thickness of 0.1 to 10 μm is formed. , Thin thickness (0.1
-10 μm), which makes it possible to reliably produce high quality ceramic green sheets. That is, a ceramic green sheet which is excellent in surface smoothness, high in density, has high tensile strength, and has a uniform distribution of a resin such as a binder and a plasticizer, which is suitable for use in manufacturing a multilayer ceramic electronic component is obtained. It becomes possible.

The method for manufacturing a multilayer ceramic electronic component of the present invention (Claim 11) is the same as that of the present invention (Claims 1 to 5).
A ceramic green sheet is formed using the ceramic slurry produced by the method 9), and the ceramic green sheet is laminated, cut, and fired with the base metal internal electrode, and then the external electrode is formed. It is possible to obtain a high-quality and highly reliable multilayer ceramic electronic component having characteristics.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a structure of a laminated ceramic capacitor manufactured by laminating ceramic green sheets.

FIG. 2 is a diagram illustrating a method for manufacturing a multilayer ceramic capacitor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic element 2 Internal electrode 3a, 3b External electrode 11 Electrode installation sheet 21 Sheet for outer layer

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 4G030 AA09 AA10 AA16 AA27 AA36 AA37 AA40 BA12 GA04 GA11 GA16 5E001 AB03 AC09 AE00 AE01 AE02 AE03 AE04 AF06 AH00 AH01 AH05 AH06 AH09 AJ02 5E082 AA38 EBBC BC FG27 FG41 FG54 GG10 GG11 GG28 JJ03 JJ12 JJ23 LL01 LL02 LL03 LL35 MM22 MM24 PP07 PP09

Claims (11)

[Claims] 1. A method for producing a ceramic slurry used for producing a ceramic electronic component, comprising: dispersing a ceramic powder having an average particle size of 0.01 to 1 μm and a dispersion medium in a medium type using a dispersion medium such as a boulder or beads. Mixing and crushing steps to obtain a mixed and crushed slurry by mixing and crushing by a method, and a high-pressure dispersion step of obtaining a dispersed slurry by subjecting the mixed and crushed slurry to high pressure dispersion at a pressure of 100 kg / cm ² or more. A method for producing a ceramic slurry, comprising: 2. The method for producing a ceramic slurry according to claim 1, wherein mixing and crushing are performed by the medium-type dispersion method in a state where a binder is added. 3. A method for producing a ceramic slurry used for producing a ceramic electronic component, comprising: disposing a ceramic powder having an average particle size of 0.01 to 1 μm and a dispersion medium containing no binder, such as a cobblestone or beads. A mixing / crushing step of mixing / crushing by a medium-type dispersion method using a dispersion medium to obtain a mixing / crushing slurry;
a high-pressure dispersion step of obtaining a dispersion slurry by performing high-pressure dispersion at a pressure of kg / cm ² or more. 4. A method for producing a ceramic slurry used for producing a ceramic electronic component, comprising: a step of mixing a ceramic powder having an average particle size of 0.01 to 1 μm with a dispersion medium containing no binder, such as cobblestone or beads. A mixing and crushing step of mixing and crushing to obtain a mixed and crushed slurry by a medium-type dispersion method using a dispersion medium, and a high pressure dispersion of the mixed and crushed slurry at a pressure of 100 kg / cm ² or more. A primary high-pressure dispersion step of obtaining a primary dispersion slurry, and adding a binder to the primary dispersion slurry;
A high-pressure dispersion step of obtaining a secondary dispersion slurry (final dispersion slurry) by high-pressure dispersion at a pressure of 00 kg / cm ² or more. 5. A method for producing a ceramic slurry used for producing a ceramic electronic component, comprising: a step of mixing a ceramic powder having an average particle size of 0.01 to 1 μm with a dispersion medium containing no binder, such as cobbles or beads. A primary mixing / crushing step of mixing / crushing by a medium-type dispersion method using a dispersion medium to obtain a primary mixing / crushing slurry; and adding a binder to the primary mixing / crushing slurry, and dispersing cobblestones and beads. A secondary mixing and crushing step of mixing and crushing by a medium-type dispersion method using a medium to obtain a secondary mixing and crushing slurry, and applying the secondary mixing and crushing slurry at a pressure of 100 kg / cm ² or more. A high-pressure dispersion step of obtaining a dispersion slurry by high-pressure dispersion. 6. The method according to claim 1, wherein the binder is a binder solution obtained by stirring and mixing a solvent and a binder and dispersing the mixture under a high pressure of 100 kg / cm ² or more. Manufacturing method of ceramic slurry. 7. A binder mixed solution obtained by stirring and mixing a solvent and a binder as the binder is used in an amount of 40 to 100.
The method for producing a ceramic slurry according to any one of claims 1 to 5, wherein a binder solution heated and refluxed at ℃ is used. 8. The method for producing a ceramic slurry according to claim 1, wherein the viscosity of the dispersion slurry (final dispersion slurry) is 0.01 to 0.1 Pas. 9. The method for producing a ceramic slurry according to claim 1, wherein said medium-type dispersion method is a method using a ball mill or a bead mill. 10. A method of forming a ceramic green sheet having a thickness of 0.1 to 10 μm by forming the ceramic slurry produced by the method of claim 1 into a sheet on a predetermined base material. Characteristic method of manufacturing ceramic green sheets. 11. A ceramic green sheet is formed by using the ceramic slurry produced by the method of claim 1, and the ceramic green sheet is laminated with a base metal internal electrode, cut and fired, and then an external electrode is formed. A method for manufacturing a multilayer ceramic electronic component, comprising: