JP2001196261A - Method of manufacturing laminated ceramic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a laminated ceramic capacitor whereby the homogeneity of a dielectric layer is improved to reduce the characteristics variation of the capacitor. SOLUTION: The manufacturing method comprises a step of mixing a main material powder of the dielectric layer with a subsidiary material powder to obtain a mixed powder, a step of mixing the mixed powder with a binder to precursor, and a step of baking this precursor. Before the step of obtaining the mixed powder, the main material powder is processed by a jet mill, or the mixing of the main material powder with the subsidiary material powder or the mixing of the mixed powder with the binder is executed by a jet mill.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer ceramic capacitor.

[0002]

2. Description of the Related Art In recent years, ceramic electronic components have been rapidly becoming smaller and more sophisticated in order to cope with miniaturization of electronic devices. The same holds true for multilayer ceramic capacitors, in which the performance of dielectric materials is improved, and the thickness and thickness of dielectric layers are being increased. As an approach to these goals, various element technologies such as blending, molding, and firing of the raw material powder constituting the dielectric layer have been developed.

A multilayer ceramic capacitor has a structure in which dielectric layers and internal electrode layers are alternately stacked. The dielectric layer is usually composed of a sintered body of a mixed powder obtained by adding a main raw material powder such as barium titanate as a main component and various auxiliary raw material powders. In such a multilayer ceramic capacitor, a main raw material powder and an auxiliary raw material powder are mixed, the mixed powder and a binder are mixed and molded into a sheet, and the molded body and an internal electrode layer are laminated. It is manufactured by firing. A medium stirring type mill such as a ball mill is used for mixing the main raw material powder and the auxiliary raw material powder and mixing the mixed powder with the binder.

[0004]

It is considered that the characteristics of the multilayer ceramic capacitor are greatly affected by the homogeneity of the dielectric layer. It is considered that the homogeneity of the dielectric layer is caused by the dispersibility of the auxiliary raw material powder in the main raw material powder, the dispersibility of the main raw material powder in the binder, and the uniformity of the growth of the sintered grains. However, in the conventional manufacturing method,
It is hard to say that these factors have been sufficiently considered, and the composition of the dielectric layer and the sintered particle diameter tended to vary. Therefore, the conventional multilayer ceramic capacitor is composed of such a heterogeneous dielectric layer, so that the electric field distribution when a voltage is applied becomes non-uniform, and initial characteristics such as a breakdown voltage and durability are deteriorated. There has been a problem that the variation increases.

The present invention improves the homogeneity of a dielectric layer,
An object of the present invention is to provide a method for manufacturing a multilayer ceramic capacitor capable of reducing variations in the characteristics of the capacitor.

[0006]

In order to achieve the above object, a first method of manufacturing a multilayer ceramic capacitor according to the present invention is a method of manufacturing a multilayer ceramic capacitor in which a dielectric layer and an electrode layer are stacked. Mixing the main raw material powder and the auxiliary raw material powder to obtain a mixed powder, forming the mixed powder to obtain a dielectric layer precursor, and firing the dielectric layer precursor. And obtaining the dielectric layer by treating the main raw material powder with a jet mill before the step of obtaining the mixed powder.

[0007] With this configuration, the particle size distribution of the main raw material powder is adjusted, the dispersibility of the auxiliary raw material powder in the main raw material powder is improved, and partial abnormal grain growth during sintering is prevented. It becomes possible to suppress. As a result, the homogeneity of the dielectric layer can be improved, and the variation in the characteristics of the multilayer ceramic capacitor can be reduced.

In order to achieve the above object, a second manufacturing method of the present invention is a method for manufacturing a multilayer ceramic capacitor in which a dielectric layer and an electrode layer are laminated. Mixing the powder with a body to obtain a mixed powder, forming the mixed powder to obtain a dielectric layer precursor, and firing the dielectric layer precursor to obtain the dielectric layer. Wherein, in the step of obtaining the mixed powder, the main raw material powder and the auxiliary raw material powder are mixed by a jet mill.

With this configuration, it is possible to improve the dispersibility of the auxiliary raw material powder in the main raw material powder, improve the homogeneity of the dielectric layer, and reduce the variation in the characteristics of the multilayer ceramic capacitor. Can be reduced. In addition, when the main raw material powder and the auxiliary raw material powder are mixed by a medium stirring mill as in the conventional manufacturing method, there is a problem that a long time is required for the treatment and foreign substances may be mixed from the medium. there were. However, according to the second manufacturing method of the present invention, such a problem can be reduced,
By shortening the processing time and suppressing the contamination, it is possible to improve the manufacturing efficiency and the yield.

To achieve the above object, a third manufacturing method of the present invention is a method for manufacturing a multilayer ceramic capacitor in which a dielectric layer and an electrode layer are laminated, comprising a main raw material powder and a sub raw material powder. Mixing the powder with the body to obtain a mixed powder, and mixing the mixed powder and a binder to obtain a slurry,
Forming a slurry to obtain a dielectric layer precursor,
Baking the dielectric layer precursor to obtain the dielectric layer. In the step of obtaining the slurry, the mixed powder and the binder are mixed by a jet mill.

With this configuration, the dispersibility of the powder mixture in the binder can be improved, the homogeneity of the dielectric layer can be improved, and the variation in the characteristics of the multilayer ceramic capacitor can be reduced. it can. In addition, when the mixed powder and the binder are mixed by a medium stirring mill as in the conventional manufacturing method, there is a problem that a long time is required for the treatment and that there is a possibility that foreign matter may be mixed in from the medium. However, according to the third manufacturing method of the present invention, such a problem can be reduced, and the manufacturing efficiency and the yield can be improved by shortening the processing time and suppressing the inclusion of foreign matter.

In the first, second and third manufacturing methods, it is preferable that the treatment by the jet mill is performed in a wet manner. According to this preferred example, the processing time can be more reliably reduced, and the homogeneity of the dielectric layer can be improved.

[0013] In the first, second and third production methods, the main raw material powder comprises barium titanate, strontium titanate, calcium titanate, magnesium titanate, strontium zirconate and calcium zirconate. It is preferable to include at least one selected from the group consisting of:

[0014]

(First Embodiment) A first embodiment of the present invention.
A method for manufacturing the multilayer ceramic capacitor according to the embodiment will be described.

First, an inorganic powder (hereinafter, referred to as a "main raw material powder") serving as a main raw material of the dielectric layer is processed using a jet mill. By this jet mill treatment, the aggregated particles of the main raw material powder are crushed, and the uniformity of the particle size distribution can be improved.

The main raw material powder is not particularly limited, and those conventionally known as dielectrics for capacitors can be used. For example, barium titanate, strontium titanate, calcium titanate, and the like can be used. Magnesium titanate, strontium zirconate or calcium zirconate or mixtures thereof can be used. In particular, it is preferable to use barium titanate, strontium titanate, a solid solution of strontium titanate and calcium titanate, a solid solution of magnesium titanate and calcium titanate, or a solid solution of strontium zirconate and calcium zirconate.
Further, impurities such as alkaline earth metals other than barium, iron, silicon and aluminum may be mixed in the main raw material powder. In this case, the impurity concentration is several hundreds.
It is preferably at most 0 ppm.

The average particle size of the main raw material powder is 0.1 to
It is preferably 1.0 μm, more preferably 0.3 to 0.5 μm. If the average particle size is less than 0.1 μm, abnormal grain growth may appear remarkably during sintering. If the average particle size exceeds 1.0 μm, the number of particles filled in the dielectric layer in the thickness direction decreases. This is because the reliability as an electronic component may decrease.

The processing by the jet mill is a processing in which a compressed gas of a predetermined pressure is injected, the raw material powder particles are accelerated by the jet stream, and the particles collide with each other to be pulverized. In the production method of the present invention, the jet mill treatment is preferably performed in a wet manner, that is, in a state where the main raw material powder is suspended in an appropriate solvent.

Water and organic solvents can be used as a solvent for suspending the main raw material powder. Suitable organic solvents include, for example, alcohols such as ethanol.

The mixing ratio of the main raw material powder and the solvent is as follows:
The amount of the solvent is suitably 10 to 30 parts by weight, preferably 15 to 20 parts by weight, based on 100 parts by weight of the main raw material powder. If it exceeds 30 parts by weight, the powder may precipitate during processing and the operability may be deteriorated. If it is less than 10 parts by weight,
This is because the viscosity of the slurry becomes too high and the pulverization and mixing may not proceed smoothly.

The processing pressure of the jet mill is 50 to 150
MPa, preferably 70 to 120 MPa, more preferably 90 to 100 MPa. 50MP
If it is less than a, it may be difficult to sufficiently disintegrate the agglomerated particles, and if it exceeds 150 MPa, excessively fine particles are expressed, and abnormal grain growth may occur during sintering. It is.

The number of times of processing by the jet mill is usually set according to the processing pressure. The appropriate number of treatments is, for example, preferably 15 or more when the treatment pressure is 50 MPa, and more preferably 20 or more.
When the pressure is 0 MPa, it is preferably at least 3 times, more preferably at least 5 times. The upper limit of the number of treatments is not particularly limited, but from the viewpoint of manufacturing efficiency, when the treatment pressure is set to 50 MPa, 25 treatments or less and 150 MPa
In this case, 10 or less times is appropriate.

After the processing by the jet mill is performed,
The solvent is removed from the slurry, and a processed main raw material powder is obtained. Further, the processed main raw material powder may be subjected to processing such as crushing and removal of coarse particles as necessary.

Next, the treated main raw material powder and an inorganic powder other than the main raw material powder (hereinafter, referred to as “sub raw material powder”) are mixed to obtain a mixed powder. The mixing method is not particularly limited. For example, the mixing can be performed using a medium stirring type mill such as a ball mill.

Examples of the auxiliary raw material powder include a sintering aid, a reduction inhibitor, a shifter (an additive for adjusting the Curie temperature), a depressor (an additive for reducing a change in the relative permittivity with temperature), and the like. No. Specifically, Mn
₃ O ₄ , Dy ₂ O ₃ , MgO, BaCO ₃ , CaCO ₃ , Si
O ₂ , Al ₂ O ₃ , Y ₂ O ₃ , V ₂ O ₅ , Ho ₂ O ₃ , Er ₂ O ₃
Etc. can be used. The amount of the auxiliary raw material powder is suitably 0.005 to 6 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the main raw material powder.

Subsequently, the mixed powder is mixed with a binder and, if necessary, a solvent to prepare a slurry. As the binder, a butyral resin, an acrylic resin, or the like can be used. Further, the mixing method is not particularly limited, and for example, the mixing can be performed using a medium stirring type mill such as a ball mill.

Next, the slurry is molded to prepare a dielectric layer precursor. The molding method is not particularly limited, but for example, a doctor blade method or the like can be adopted.

The dielectric layer precursor is laminated with the electrode layer precursor to obtain a laminate. As the electrode layer precursor, for example,
A conductive paste obtained by mixing a binder and a solvent with a base metal powder such as copper, nickel or cobalt can be used.

Next, after performing a binder removal treatment or the like as necessary, the laminate is fired. The firing temperature and the firing time are appropriately set according to the type of the dielectric layer and the electrode layer. In addition, the firing atmosphere is preferably a non-oxidizing atmosphere in order to suppress oxidation of the electrode layer.

Further, external electrodes and the like are appropriately formed on the fired laminate to obtain a multilayer ceramic capacitor.

According to such a manufacturing method, by treating the main raw material powder by the jet mill, the aggregated particles of the main raw material powder are dissociated, and the variation in the particle size distribution can be reduced. Therefore, in addition to being able to suppress partial abnormal grain growth during sintering, the dispersibility of the auxiliary material powder in the main material powder is improved, and the uniformity of the reaction during sintering is improved. Can be improved. (Second Embodiment) A method for manufacturing a multilayer ceramic capacitor according to a second embodiment of the present invention will be described.

First, a mixed powder of a main raw material powder and an auxiliary raw material powder is processed by a jet mill. That is, the main raw material powder and the auxiliary raw material powder are mixed by a jet mill.
By this jet milling, the aggregated particles of the main raw material powder and the auxiliary raw material powder are crushed to improve the uniformity of the particle size distribution, and the dispersibility of the auxiliary raw material powder in the main raw material powder is improved. Note that, as the main raw material powder and the auxiliary raw material powder, those similar to those in the first embodiment can be used in the same mixing ratio.

The jet mill treatment is preferably performed in a wet manner. As a solvent for suspending the mixed powder, an organic solvent such as water and alcohol can be used.

The mixing ratio of the mixed powder and the solvent is suitably 10 to 30 parts by weight, preferably 15 to 20 parts by weight, based on 100 parts by weight of the mixed powder. If the amount exceeds 30 parts by weight, the powder may precipitate during processing and the operability may be deteriorated. If the amount is less than 10 parts by weight, the viscosity of the slurry may be too high and the pulverization and mixing may not proceed smoothly. Because there is.

The conditions such as the processing pressure and the number of times of the jet mill can be the same as those in the first embodiment.

After the processing by the jet mill is performed,
The solvent is removed from the slurry to obtain a processed mixed powder. In addition, the processed mixed powder, if necessary,
Processing such as crushing and removal of coarse particles may be performed.

Subsequently, the treated mixed powder is mixed with a binder and, if necessary, a solvent to prepare a slurry,
This is molded to produce a dielectric layer precursor. After laminating the dielectric layer precursor and the electrode layer precursor, and performing a binder removal process or the like as necessary, it is fired. Further, external electrodes and the like are appropriately formed to obtain a multilayer ceramic capacitor. These steps can be performed in the same manner as in the first embodiment.

According to such a production method, the main raw material powder and the auxiliary raw material powder are mixed by a jet mill, whereby the dispersibility of the auxiliary raw material powder in the main raw material powder is improved, and It is possible to improve the uniformity of the reaction at the time of sintering. Further, by using a jet mill for mixing the main raw material powder and the auxiliary raw material powder, contamination of impurities can be suppressed and the processing time can be shortened as compared with the case where a medium stirring mill is used.

(Third Embodiment) A method for manufacturing a multilayer ceramic capacitor according to a third embodiment of the present invention will be described.

First, the main raw material powder and the auxiliary raw material powder are mixed to obtain a mixed powder. The mixing method is not particularly limited. For example, the mixing can be performed using a medium stirring type mill such as a ball mill. Note that, as the main raw material powder and the auxiliary raw material powder, those similar to those in the first embodiment can be used in the same mixing ratio.

Next, the mixture of the mixed powder, the binder and the solvent is processed by a jet mill to prepare a slurry. That is, the mixed powder, the binder, and the solvent are mixed by a jet mill. By this jet mill treatment, the dispersibility of the mixed powder in the slurry is improved.

As the binder, a butyral resin, an acrylic resin, or the like can be used. The ratio of the binder is 2 to 1 with respect to 100 parts by weight of the mixed powder.
It is appropriate to use 5 parts by weight, preferably 5 to 10 parts by weight.

Further, as the solvent, ethanol, butyl acetate, pure water and the like can be used. The proportion of the solvent is suitably 10 to 30 parts by weight, preferably 15 to 20 parts by weight, based on 100 parts by weight of the mixed powder. If it exceeds 30 parts by weight, the powder may precipitate during processing and the operability may be deteriorated. If it is less than 10 parts by weight,
This is because the viscosity of the slurry becomes too high and the mixing may not proceed smoothly.

The conditions such as the processing pressure and the number of times of the jet mill can be the same as in the first embodiment.

Subsequently, the slurry is formed to prepare a dielectric layer precursor. After laminating the dielectric layer precursor and the electrode layer precursor, and performing a binder removal process or the like as necessary, it is fired. Further, external electrodes and the like are appropriately formed,
A multilayer ceramic capacitor is obtained. These steps can be performed in substantially the same manner as in the first embodiment.

According to such a production method, the raw material powder and the binder are mixed by the jet mill, whereby the dispersibility of the raw material powder in the binder is improved, and the uniformity of the reaction during sintering is improved. It can be improved. Further, by using a jet mill for mixing the raw material powder and the binder, the mixing of impurities can be suppressed and the processing time can be reduced as compared with the case where a medium stirring type mill is used.

[0047]

EXAMPLES (Example 1) Barium titanate powder (BT-03, manufactured by Sakai Chemical Industry Co., Ltd .: average particle diameter 0.3 μm)
15 parts by weight of pure water was added to 100 parts by weight, and this was treated using a wet jet mill (manufactured by Genus Corporation) to obtain a suspension. The treatment pressure was 150 MPa, and the number of treatments was three. The suspension after the treatment was dried using a drum dryer set at 120 ° C. After the dried powder was crushed in an alumina mortar, coarse particles were removed through a 30-mesh sieve. With respect to 100 parts by weight of the dry powder, 0.04 parts by weight of Mn ₃ O ₄ , 2.0 parts by weight of Dy ₂ O ₃ , 0.25 parts by weight of MgO, and 1.0 part by weight of BaCO ₃ .
0 part by weight, 1.0 part by weight of CaCO ₃ and 1.0 part by weight of SiO ₂ were added to obtain a mixed powder. 200 parts by weight of pure water was added to 100 parts by weight of the mixed powder, and mixed with a zirconia ball as a medium in a ball mill for 20 hours to obtain a suspension. The suspension was dried using a drum dryer set at 120 ° C., crushed in an alumina mortar, and coarse grains were removed through a 30-mesh sieve. Next, 100 parts by weight of the obtained dry powder, 7 parts by weight of butyral resin, and 15 parts by weight of butyl acetate were mixed with a zirconia ball as a medium in a ball mill for 6 hours to prepare a dielectric slurry. A dielectric green sheet having a thickness of 6 μm was prepared using the dielectric slurry, and an internal electrode pattern was formed on the surface of the dielectric green sheet using a nickel paste. A laminate was prepared by laminating 100 dielectric green sheets on which internal electrode patterns were formed. The dielectric slurry is used to have a thickness of 50 μm.
Was prepared, and four such dielectric green sheets were laminated on the upper and lower surfaces of the laminate as protective layers. This was thermocompression bonded to produce a 3216 size multilayer capacitor green chip.

Subsequently, after performing the binder removal treatment, the multilayer capacitor green chip was fired. In the binder removal treatment, the temperature is increased to 400 ° C. in the atmosphere at a rate of 15 ° C./h,
After holding at 400 ° C. for 5 hours, the furnace was cooled down. Further, in the firing, the temperature was raised from room temperature to 900 ° C. at a rate of 200 ° C./h in a mixed gas atmosphere of nitrogen and hydrogen. After adjusting the oxygen partial pressure to be two orders of magnitude smaller than the pressure, the temperature was raised to 1325 ° C. at 200 ° C./h while operating the mass flow controller so that the oxygen partial pressure was maintained.
After maintaining at 325 ° C for 2 hours, the temperature was lowered to room temperature at 200 ° C / h. Thereafter, the fired chip is chamfered by barrel polishing, an external electrode is formed by applying a copper paste to a portion where the internal electrode is taken out and baking to form an external electrode, and sequentially applying nickel plating and solder plating to the external electrode. Thus, a multilayer ceramic capacitor was manufactured.

(Example 2) Barium titanate powder 100
Parts by weight, 0.04 parts by weight of Mn ₃ O ₄ , 2.0 parts by weight of Dy ₂ O ₃ , 0.25 parts by weight of MgO,
₃ , 1.0 part by weight, 1.0 part by weight of CaCO ₃ ,
1.0 part by weight of O ₂ was weighed into a pot. Pure water is added to the raw material powder, and pure water 15
The suspension was added at a ratio of parts by weight and mixed using a wet jet mill (manufactured by Genus Corporation) to obtain a suspension. The treatment pressure was 150 MPa, and the number of treatments was three. The same raw material powder as in Example 1 was used. The suspension after the treatment was dried using a drum dryer set at 120 ° C., and then crushed in an alumina mortar.
Coarse grains were removed through a 0 mesh sieve. next,
100 parts by weight of this dry powder, 7 parts by weight of butyral resin, and 15 parts by weight of butyl acetate were mixed in a ball mill for 6 hours using zirconia balls as a medium to prepare a dielectric slurry. Using this dielectric slurry, a multilayer capacitor green chip is manufactured by the same operation as in Example 1, and after performing binder removal processing and firing, external electrode formation, nickel plating and solder plating are sequentially performed. A multilayer ceramic capacitor was manufactured.

Example 3 Barium titanate powder 100
Parts by weight, 0.04 parts by weight of Mn ₃ O ₄ , 2.0 parts by weight of Dy ₂ O ₃ , 0.25 parts by weight of MgO,
₃ , 1.0 part by weight, 1.0 part by weight of CaCO ₃ ,
1.0 part by weight of O ₂ was weighed into a pot. Pure water is added to this raw material powder, and pure water 20
0 parts by weight and mixed for 20 hours in a ball mill using zirconia balls as a medium to obtain a suspension. The suspension was dried using a drum dryer set at 120 ° C., then crushed in an alumina mortar, and passed through a 30-mesh sieve to remove coarse particles. Next, the dry powder 10
0 parts by weight, butyral resin 7 parts by weight, and butyl acetate 1
5 parts by weight were mixed and treated using a wet jet mill (manufactured by Genus Corporation) to obtain a dielectric slurry. The treatment pressure was 100 MPa, and the number of treatments was three. Using this dielectric slurry, a multilayer capacitor green chip is manufactured by the same operation as in Example 1, and after performing binder removal processing and firing, external electrode formation, nickel plating and solder plating are sequentially performed. A multilayer ceramic capacitor was manufactured.

Comparative Example 100 parts by weight of barium titanate powder, 0.04 part by weight of Mn ₃ O _4, and 2.0 parts by weight of Dy ₂ O ₃
0 parts by weight, 0.25 parts by weight of MgO, 1.0 parts by weight of BaCO ₃ , 1.0 parts by weight of CaCO ₃ , and SiO ₂
And 1.0 part by weight was weighed into a pot. Pure water was added to the raw material powder at a ratio of 200 parts by weight of pure water to 100 parts by weight of the total powder, and mixed by a ball mill using zirconia balls as a medium for 20 hours to obtain a suspension. The suspension was dried using a drum dryer set at 120 ° C., crushed in an alumina mortar, and passed through a 30-mesh sieve to remove coarse particles. Next, 100 parts by weight of the dried powder, 7 parts by weight of butyral resin, and 15 parts by weight of butyl acetate were mixed in a ball mill using zirconia balls as a medium.
After mixing for a time, a dielectric slurry was obtained. Using this dielectric slurry, a multilayer capacitor green chip is manufactured by the same operation as in Example 1, and after performing binder removal processing and firing, external electrode formation, nickel plating and solder plating are sequentially performed. A multilayer ceramic capacitor was manufactured.

With respect to the above Examples and Comparative Examples, the capacitance failure rate, dielectric loss tangent failure rate, high temperature life failure rate, and average accelerated life of the manufactured multilayer ceramic capacitors were evaluated.
Table 1 shows the evaluation results.

[0053]

[Table 1]

In the above Examples and Comparative Examples,
The variation of the dielectric breakdown voltage of the manufactured multilayer ceramic capacitor was evaluated. The evaluation results are shown in FIG. 1 for Example 1, FIG. 2 for Example 2, FIG. 3 for Example 3, and FIG. 4 for Comparative Example.

Each evaluation method is as follows.

(Capacitance defective rate) The capacitance was measured for 500 multilayer ceramic capacitors, and the number of capacitors whose measured values did not fall within a range of ± 10% of the designed capacitance (3.3 μF) as a center value was determined. Examined. The capacitance was measured under the conditions of normal temperature, an effective voltage of 1 V, and a frequency of 1 kHz.

(Dielectric loss tangent defect ratio) The dielectric loss tangent (tan δ) of 500 laminated ceramic capacitors was measured, and the number of those having a measured value exceeding 0.02 was examined. The dielectric loss tangent is normal temperature, effective voltage 1 V, frequency 1 kHz.
It measured on condition of.

(High temperature life failure rate) The insulation resistance was measured for 500 multilayer ceramic capacitors when a DC voltage of 12.6 V was applied at 125 ° C. for 1000 hours.
The number of samples whose measured value was 5 × 10 ⁸ Ω or less was examined.

(Average Accelerated Life) For the 24 multilayer ceramic capacitors, a DC voltage of 72 V was continuously applied at 150 ° C., and the time required until the insulation resistance became 5 × 10 ⁸ Ω or less was measured. The value was determined.

(Distribution of Breakdown Voltage) The breakdown voltage was measured for 50 multilayer ceramic capacitors, and the distribution of the measured values was examined.

As shown in Table 1, the multilayer ceramic capacitors manufactured in Examples 1 to 3 have less occurrence of defects in capacitance, dielectric loss tangent and high temperature life than those manufactured in Comparative Example. In addition, the characteristics of the accelerated life were improved by 20% or more. In particular, according to Examples 2 and 3, better results were obtained than in Example 1.

As shown in FIGS. 1 to 4, the multilayer ceramic capacitors manufactured in Examples 1 to 3 have greatly reduced variation in dielectric breakdown voltage distribution as compared with those manufactured in Comparative Example. It was also confirmed that the average dielectric breakdown voltage value was increased.

[0063]

As described above, according to the first manufacturing method of the present invention, there is provided a method of manufacturing a multilayer ceramic capacitor in which a dielectric layer and an electrode layer are stacked, Obtaining a mixed powder by mixing the mixed powder and the auxiliary raw material powder, forming the mixed powder to obtain a dielectric layer precursor, and firing the dielectric layer precursor to form the dielectric layer. And a step of processing the main raw material powder by a jet mill before the step of obtaining the mixed powder, whereby variations in characteristics of the multilayer ceramic capacitor can be reduced.

According to the second manufacturing method of the present invention,
A method for producing a multilayer ceramic capacitor comprising a dielectric layer and an electrode layer laminated, wherein a step of mixing a main raw material powder and an auxiliary raw material powder to obtain a mixed powder, and forming the mixed powder Obtaining a dielectric layer precursor, and firing the dielectric layer precursor to obtain the dielectric layer. In the step of obtaining the mixed powder, the main raw material powder and the auxiliary By mixing the raw material powder with a jet mill, variations in the characteristics of the multilayer ceramic capacitor can be reduced.

According to the third manufacturing method of the present invention,
What is claimed is: 1. A method for manufacturing a multilayer ceramic capacitor comprising a dielectric layer and an electrode layer laminated, comprising: mixing a main raw material powder and an auxiliary raw material powder to obtain a mixed powder; Mixing the slurry to obtain a slurry, forming the slurry to obtain a dielectric layer precursor, and firing the dielectric layer precursor to obtain the dielectric layer, wherein the slurry In the step of obtaining, by mixing the mixed powder and the binder by a jet mill,
Variations in the characteristics of the multilayer ceramic capacitor can be reduced.

[Brief description of the drawings]

FIG. 1 is a view showing a breakdown voltage distribution of a multilayer ceramic capacitor in Example 1.

FIG. 2 is a diagram showing a breakdown voltage distribution of the multilayer ceramic capacitor in Example 2.

FIG. 3 is a diagram showing a breakdown voltage distribution of a multilayer ceramic capacitor in Example 3.

FIG. 4 is a diagram showing a breakdown voltage distribution of a multilayer ceramic capacitor in a comparative example.

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Claims (5)

[Claims] 1. A method for manufacturing a multilayer ceramic capacitor comprising a dielectric layer and an electrode layer laminated, comprising: mixing a main raw material powder and an auxiliary raw material powder to obtain a mixed powder; Forming a mixed powder to obtain a dielectric layer precursor, and firing the dielectric layer precursor to obtain the dielectric layer, before the step of obtaining the mixed powder, A method for manufacturing a multilayer ceramic capacitor, comprising processing a main raw material powder by a jet mill. 2. A method for manufacturing a multilayer ceramic capacitor comprising a dielectric layer and an electrode layer laminated, comprising: mixing a main raw material powder and an auxiliary raw material powder to obtain a mixed powder; Forming a mixed powder to obtain a dielectric layer precursor, and firing the dielectric layer precursor to obtain the dielectric layer; A method for manufacturing a multilayer ceramic capacitor, comprising mixing powder and the auxiliary raw material powder by a jet mill. 3. A method for manufacturing a multilayer ceramic capacitor comprising a dielectric layer and an electrode layer laminated, the method comprising: mixing a main raw material powder and an auxiliary raw material powder to obtain a mixed powder; A step of obtaining a slurry by mixing the mixed powder and the binder, a step of forming the slurry to obtain a dielectric layer precursor, and a step of firing the dielectric layer precursor to obtain the dielectric layer Wherein in the step of obtaining the slurry, the mixed powder and the binder are mixed by a jet mill. 4. The method for producing a multilayer ceramic capacitor according to claim 1, wherein the treatment by a jet mill is performed by a wet method. 5. The main raw material powder contains at least one selected from the group consisting of barium titanate, strontium titanate, calcium titanate, magnesium titanate, strontium zirconate and calcium zirconate. The method for manufacturing a multilayer ceramic capacitor according to any one of the above.