KR20100103388A - Barium titanate dielectric powder, method for manufacturing the same, method for manufacturing ceramic green sheet, and method for manufacturing laminated ceramic capacitor - Google Patents

Abstract

PURPOSE: Barium titanate-based dielectric material powder, a manufacturing method thereof, a manufacturing method of a ceramic green sheet, and a manufacturing method of a laminated ceramic condenser are provided to planarize the temperature property of the dielectric rate of the powder. CONSTITUTION: Barium titanate-based dielectric material powder is coated with a barium compound having BaTiO3 powder with the surface having the molar ratio of BaCO3 and BaO more than 0.55. A manufacturing method of the barium titanate-based dielectric material powder comprises the following steps: preparing the BaTiO3 powder; and dipping the BaTiO3 powder to a water based solvent. A manufacturing method of a ceramic green sheet comprises the following steps: forming sheet molding slurry containing the barium titanate-based dielectric material powder, a binder, and a dispersing agent; and molding the slurry into a sheet form.

Description

Barium titanate-based dielectric raw material powder, a method of manufacturing the same, a method of manufacturing a ceramic green sheet, and a method of manufacturing a multilayer ceramic capacitor CAPACITOR}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric ceramic raw material powder and a method for manufacturing the same. Specifically, a barium titanate-based dielectric raw material powder used in a multilayer ceramic capacitor and the like, a method for manufacturing the same, and a ceramic green sheet using the barium titanate-based dielectric raw material powder A method and a method of manufacturing a multilayer ceramic capacitor using the ceramic green sheet.

BACKGROUND ART Barium titanate (BaTiO ₃ ) -based dielectric ceramics are widely used in electronic components such as multilayer ceramic capacitors as dielectric materials.

And when using this barium titanate-type dielectric ceramic as a dielectric material, in order to improve various electrical characteristics, adding various subcomponents (for example, rare earth elements, Mg, Mn, etc.) is performed.

In particular, it is preferable that includes temperature characteristics and, in order to achieve both the reliability of the high-temperature high electric field, the employment of the auxiliary component (固溶) in the surface layer portion of the BaTiO ₃ crystal grains of the core shell structure of the dielectric constant. That is, it is preferable that a subcomponent does not exist in the part of a core, and a subcomponent exists in the part of a shell.

In addition, in order to make both the temperature characteristic of dielectric constant and the reliability in a high temperature high electric field high level, the core and the shell are concentric, and it is preferable that the state of solid solution of a subcomponent is uniform regardless of the location of crystal grains. .

However, in order to obtain crystal grains having a crystal structure of such a preferred form, it is necessary to perform an appropriate treatment on the BaTiO ₃ powder in the raw material step, and it is easy to obtain a BaTiO ₃ -based ceramic powder having desired characteristics by performing such treatment. It is a fact not to do.

Thus, in order to solve these problems, in the step of calcining BaTi0 ₃ , barium titanate-based dielectric ceramics are calcined in a predetermined CO ₂ atmosphere to form BaCO ₃ layers on the surface of BaTiO ₃ powder. The manufacturing method of is proposed (refer patent document 1).

That is, Patent Document 1 discloses that the barium carbonate is formed on the surface of the barium titanate-based powder obtained by setting the carbon dioxide partial pressure at the time of calcination of barium titanate to be 400 to 1000 ppm higher than the carbon dioxide partial pressure in the atmosphere. In the process, the method of suppressing reaction and particle growth of powders, and manufacturing a barium titanate powder of fine and uniform particle diameter is disclosed.

And when baking the molded object formed using such a barium titanate-type powder, grain growth is suppressed by the reaction inhibitory effect of barium carbonate, and the dielectric ceramic of the barium titanate-based sintered compact which consists of crystal grains of fine and uniform particle diameter is carried out. It is supposed that this is obtained.

However, as in the above-mentioned prior art, only by setting the carbon dioxide partial pressure during the calcining of barium titanate to an atmosphere of 400 to 1000 ppm, the temperature characteristics of the dielectric constant and the reliability in a high temperature high electric field may not be sufficiently improved.

This is because the carbon dioxide partial pressure at the time of calcination of barium titanate is 400-1000 ppm, and the ratio of BaC0 ₃ in the carbonate compound of Ba on the surface of barium titanate powder is not necessarily high enough. do.

Japanese Laid-Open Patent Publication No. 2007-1840

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above problems, and the barium titanate-based dielectric material powder capable of forming a dielectric ceramic having excellent reliability at high temperature high electric fields while the temperature characteristic of the dielectric constant is flattened, a method of manufacturing the same, and further, the titanic acid A method of manufacturing a ceramic green sheet using a barium-based dielectric material powder, and a multilayer ceramic capacitor capable of producing a multilayer ceramic capacitor having excellent temperature characteristics of dielectric constant and excellent reliability in high temperature high electric fields using the ceramic green sheet. An object of the present invention is to provide a manufacturing method.

Barium titanate-based dielectric material powder of the present invention,

The surface of the BaTiO ₃ powder is coated with a barium compound having a BaCO ₃ /BaO=0.55 or more in a molar ratio of BaC0 ₃ and BaO.

In addition, the barium titanate-based dielectric material powder of the present invention may contain an additive component for adjusting properties.

The method for producing a barium titanate-based dielectric material powder of the present invention is characterized by comprising a step of preparing BaTiO ₃ powder and a step of immersing the BaTiO ₃ powder in an aqueous solvent for at least 16 hours.

Further, in the production process of the barium titanate based dielectric material powder of the invention, as the BaTiO ₃ powder and BaTiO ₃ powder can be used for the additive component of the characteristics adjusting added.

In addition, the method for forming a ceramic green sheet of the present invention comprises the steps of preparing a slurry for forming a sheet containing the barium titanate-based dielectric material powder according to claim 1 or 2, a binder and a dispersion medium, and the slurry for forming the sheet. And forming a ceramic green sheet by molding into an image.

In addition, the method of manufacturing a multilayer ceramic capacitor of the present invention comprises the steps of forming an internal electrode pattern by applying a conductive paste to the ceramic green sheet formed by the method of claim 5, and the ceramic green sheet on which the internal electrode pattern is formed. Laminating and pressing to form a laminate, and firing the laminate to obtain a ceramic capacitor device having a structure in which internal electrodes are laminated through a ceramic layer.

In the barium titanate-based dielectric material powder of the present invention, the surface of BaTiO ₃ powder is covered with a barium compound having a BaCO ₃ /BaO=0.55 or more ratio in a molar ratio of BaC0 ₃ and BaO, and the proportion of BaC0 _{3 in} the barium compound is Since it is high, particle growth is suppressed by the reaction inhibitory effect of BaC0 ₃ , the temperature characteristic of dielectric constant is flat, and the barium titanate-based dielectric raw material powder having excellent reliability in high temperature high electric field can be obtained.

As in the barium titanate-based dielectric material powder of the present invention, a large BaC0 ₃ to BaO ratio (BaCO ₃ / BaO ratio) on the surface of the BaTiO ₃ powder is covered with BaC 0 ₃ and the degree of exposure of the Ti-rich surface layer. Decreases and the degree of exposure of BaO to the powder surface decreases.

In the state where BaC0 ₃ is present on the surface of the barium titanate-based dielectric material powder, grain growth is suppressed, and local grain growth is suppressed, thereby flattening temperature characteristics. In addition, in the state where the Ti rich phase does not exist on the surface, the solid solution (employment nonuniformity) of a local additional element is suppressed and the reliability with respect to high temperature high electric field load improves.

On the other hand, in a state in which BaTiO ₃ is plastically synthesized in the air, the BaC0 ₃ / BaO ratio on the surface of the powder becomes small, but by immersion in water for a long time, the elution of Ba and the eluted Ba ions on the surface of the BaTiO ₃ powder, BaC0 ₃ generated by the reaction of C0 ₂ in water is reprecipitated to increase the concentration of BaCO _{3 on} the surface, thereby obtaining the above-mentioned effect.

In addition, in the barium titanate-based dielectric material powder of the present invention, it is possible to contain an additive component for characteristic adjustment, and by including the additive component, it becomes possible to obtain a barium titanate-based dielectric material powder with further improved intended characteristics.

Moreover, rare earth elements, Mg, Mn, etc. are illustrated as an addition component for characteristic adjustment. More specifically, BaZrO ₃ , BaC0 ₃ , Gd ₂ 0 ₃ , Dy ₂ 0 ₃ , MnC0 ₃ , MgCO ₃ , Si0 _2, or the like may be added. However, the addition component is not limited to what was illustrated above.

In the method for producing a barium titanate-based dielectric material powder of the present invention, BaTi0 ₃ powder is prepared, and the BaTiO ₃ powder is immersed in an aqueous solvent for 16 hours or more, so that the ratio of BaCO ₃ to BaO ₃ is in a molar ratio. By the barium compound of /BaO=0.55 or more, the barium titanate-based dielectric material powder coated with the surface of the BaTiO ₃ powder can be efficiently produced.

In addition, it is possible to efficiently manufacture a, intended barium titanate-based dielectric material powder was further improved characteristics, comprising the additive components by using a BaTi0 ₃ powder is added to the components of the characteristics adjusting added as BaTiO ₃ powder.

In addition, as in the method of forming the ceramic green sheet of the present invention, a sheet forming slurry including the barium titanate-based dielectric material powder according to claim 1 or 2, a binder, and a dispersion medium is prepared, and the sheet forming slurry is prepared in a sheet form. When molded into a ceramic green sheet, it is possible to obtain a ceramic green sheet which is capable of forming a dielectric ceramic layer excellent in temperature characteristics of dielectric constant and excellent in high temperature high electric field during load testing and the like. Therefore, by using the ceramic green sheet of the present invention, it becomes possible to efficiently manufacture a multilayer ceramic capacitor having good characteristics.

In forming a ceramic green sheet, BaTiO ₃ coated with a barium compound having BaCO ₃ /BaO=0.55 or more in a molar ratio of BaC0 ₃ and BaO after immersing BaTi0 ₃ powder in an aqueous solvent for 16 hours or more. It is also possible to add a binder to a slurry containing powder to form a slurry for forming a sheet, and to form the slurry for forming a sheet into a sheet to form a ceramic green sheet. In this case, it is possible to efficiently obtain a slurry containing barium titanate-based dielectric raw material powder without being subjected to drying or calcining, and further after dispersing or slurrying after immersion in an aqueous solvent. By molding into a sheet, a ceramic green sheet capable of efficiently producing a multilayer ceramic capacitor having good characteristics can be efficiently produced.

This method is particularly meaningful when it is preferable to use a ceramic green sheet containing an aqueous solvent as the ceramic green sheet.

In the method of manufacturing a multilayer ceramic capacitor of the present invention, a conductive paste is applied to the ceramic green sheet produced as described above to form an internal electrode pattern, which is laminated and pressed to form a laminate, followed by firing the laminate. Since a ceramic capacitor element having a structure in which internal electrodes are laminated through a ceramic layer is obtained, it is possible to efficiently manufacture a multilayer ceramic capacitor which is excellent in temperature characteristics of dielectric constant and high in reliability at high temperature high electric fields.

FIG. 1: is a figure which shows the result (chart) of the spectrum derived from Ba3d5 / 2 and Ti2p of XPS with respect to the barium titanate type dielectric material powders of the sample numbers 1 and 3 of Table 1 in XPS.
FIG. 2 is a diagram showing the state of peak separation between BaC0 ₃ and BaO in XPS of the barium titanate-based dielectric material powder of Sample No. 1 in Table 1. FIG.
3 is a view showing the configuration of a multilayer ceramic capacitor manufactured using a barium titanate-based dielectric material powder according to an embodiment of the present invention.

EMBODIMENT OF THE INVENTION Embodiment of this invention is shown to the following, and the feature of this invention is demonstrated in detail.

Example 1

BaCO ₃ and Ti0 ₂ were prepared as starting materials, and weighed and blended so that the ratio of Ba and Ti was Ba / Ti = 1.01 (at ratio). Then, this blended raw material was mixed by a ball mill (using a PSZ media having a diameter of 2 mm) and heat-treated at 900 to 1050 ° C in air to synthesize a barium titanate compound represented by the general formula Ba _1.01 Ti0 ₃ .

Then, by milling the barium titanate-based compound, the average primary particle size to give the respectively 80㎚, 150㎚, barium titanate-based compounds 340㎚ powder (Ba _{1 .01} Ti0 ₃ powder).

Next, those of Ba _{1 .01} Ti0 ₃ 100g powder into the container with 100g of water, the time (from 1 to 120 hours) indicated in Table 1, while performing the stirring was immersed in water. Agitation, specifically by grinding media were subjected to an insert port poly (container) Ba _{1 .01} Ti0 ₃ powder and in that, rotation, dilute with water. In addition, the process is a process of dipping in water (which involves only stirred) does not involve the crushing of barium titanate-based compound powder (Ba _{1 .01} TiO ₃ powder).

Thereafter, some of them were dried immediately to obtain a barium titanate-based dielectric material powder. Then, the obtained barium titanate-based dielectric material powder was measured by XPS (quantum 2000 manufactured by PHYSICAL ELECTRONICS Co., Ltd.) and the spectrum derived from Ba3d5 / 2 and Ti2p on the surface thereof, and the barium titanate-based dielectric material was determined from the ratio of the respective peaks. The Ba / Ti ratio of the powder was calculated.

Table 1 shows the Ba / Ti ratio (mol ratio) of each barium titanate-based dielectric material powder (sample).

1 shows the results (chart) of the spectra derived from Ba3d5 / 2 and Ti2p on the surface of the barium titanate-based dielectric material powders of Sample No. 1 and Sample No. 3 in Table 1 by XPS.

In addition, the BaC0 ₃ / BaO ratio (mol ratio) of the surface of each sample was calculated by peak separation using a Gaussian Lorentz function. The results are shown in Table 1.

2 shows the state of peak separation between BaC0 ₃ and BaO in XPS of the barium titanate-based dielectric material powder of Sample No. 1 in Table 1. FIG.

The remaining slurry, within 30 minutes after the end of the stirring with respect to the Ba _{1 .01} Ti0 ₃ powder 100mol,

Dy ₂ 0 ₃ : 4mol

MnCO ₃ : 1mol

MgCO ₃ : 3mol

Si0 ₂ : 3mol

The mixture was added at a ratio of, and stirred for 15 minutes in a beaker, followed by pulverization with a forced circulation grinder (using a 0.3 mm diameter PSZ media) for 1 hour. The obtained slurry was put into an oven at 140 ° C. within 15 minutes after completion of grinding to obtain a dielectric material powder (barium titanate-based dielectric material powder containing an additive component).

An organic solvent such as a polyvinyl butyral binder and ethanol was added to the dielectric material powder (barium titanate-based dielectric material powder containing an additive component), and wet-mixed by a ball mill to prepare a ceramic slurry.

This ceramic slurry was sheet-molded by the doctor blade method so that the dielectric element thickness after baking might be set to 2 micrometers, and the rectangular green sheet was obtained.

Next, a conductive paste containing Ni as a conductive component was screen printed on the ceramic green sheet, and an internal electrode pattern (conductive paste layer) serving as an internal electrode was formed after firing.

From there, the ceramic green sheet in which the internal electrode pattern is formed and the ceramic green sheet in which the internal electrode pattern is not formed are laminated and pressed in a predetermined order, and then cut, and the internal electrode patterns are alternately drawn out on the opposite end faces. A laminate having a structure obtained was obtained. In addition, in order to measure the sintered compact, the end plate of the same dimension as a laminated body was produced.

The laminate and the single plate were heated to 350 ° C. to remove the binder, and then maintained at a maximum temperature of 1230 ° C. and an oxygen partial pressure of 10 ^{−9 · 5} MPa for 120 minutes, whereby a ceramic capacitor device having a structure in which internal electrodes were laminated through a ceramic layer. (Ceramic laminate) was obtained.

Cu pastes (conductive pastes) containing glass flits were applied to both end surfaces of the obtained ceramic capacitor elements, and baked at a temperature of 800 ° C. in an N ₂ atmosphere to form external electrodes conducting with the internal electrodes. As a result, a multilayer ceramic capacitor having a structure as shown in FIG. 3 is obtained.

In addition, as shown in Fig. 3, the multilayer ceramic capacitor has internal electrodes at both ends of the ceramic elements (capacitor elements) 1 arranged such that the internal electrodes 2a and 2b face each other via the ceramic layer (dielectric layer) 3. The external electrodes 4a and 4b are arranged so as to conduct with the 2a and 2b.

The external dimensions of the multilayer ceramic capacitor produced as described above were 1.6 mm wide, 3.2 mm long and 0.8 mm thick, and the thickness t (FIG. 3) of the ceramic layer interposed between the internal electrodes was 2 μm. The total number of effective dielectric layers (ceramic layers) was 100, and the counter electrode area per layer was 2.1 mm 2.

The temperature characteristic of the capacitance was measured for the multilayer ceramic capacitor thus obtained.

As an index of the temperature characteristic, the rate of change of the capacitance at 125 ° C was measured based on the capacitance at 25 ° C. The capacitance was measured by applying an alternating electric field of 1 kHz and 1 Vrms.

The high temperature load life test was performed by applying a voltage of 60 V at a temperature of 125 ° C. and measuring the change over time of the insulation resistance. In addition, the high temperature load life test was performed on 50 samples, and it determined that the sample whose insulation resistance value was 100 k ohm or less until 2000 hours passed was faulty.

The measurement result of the temperature characteristic (rate of change in the capacitance) and the occurrence rate of failure in the high temperature load life test are shown together with Table 1. In addition, in Table 1, the sample with * attached to the sample number is a sample outside the scope of the present invention.

The characteristics of each sample will be described below with reference to Table 1.

[About Samples of Sample Nos. 1-5]

The barium titanate-based dielectric material powders of Sample Nos. 1 to 5 in Table 1 are barium titanate-based dielectric material powders prepared by changing the immersion time in water using BaTi0 ₃ having an average primary particle diameter of 150 nm.

From the measurement results of the samples of the samples Nos. 1 to 5, it was confirmed that the longer the immersion time, the larger the BaC0 ₃ / BaO ratio measured by XPS, thereby improving the temperature characteristics and reliability.

Further, it was confirmed that the barium titanate-based dielectric material powder of BaCO ₃ /BaO≧0.55 was obtained by the immersion time being 16 h or more.

On the other hand, in the case of the sample of Sample No. 1 having the immersion time in water of 1 h, BaC0 ₃ /BaO=0.47 was low, and thus, the preferred barium titanate-based dielectric material powder could not be obtained.

In addition, when the multilayer ceramic capacitor was manufactured using the barium titanate-based dielectric material powder having the immersion time of Sample Nos. 2 to 5 of 16 h or more among Sample Nos. 1 to 5, the number of failures in the high temperature load life test was zero. It was confirmed that a multilayer ceramic capacitor having high temperature characteristics (X7S characteristics) with high reliability under high temperature load conditions and a change rate of capacitance of less than ± 22% was obtained.

On the other hand, when a multilayer ceramic capacitor was manufactured using the barium titanate-based dielectric material powder of Sample No. 1 having a immersion time in water of 1 h, the number of failures in the high temperature load life test was 42, which was low in reliability under high temperature load conditions. It was also confirmed that the rate of change of the capacitance was also unfavorable at -23.3%.

[Samples of Sample Nos. 6 and 7]

The barium titanate-based dielectric material powders of Sample Nos. 6 and 7 shown in Table 1 are barium titanate-based dielectric material powders prepared by changing the immersion time into 1h and 48h using BaTi0 ₃ having an average primary particle diameter of 80 nm. .

From the results of the measurement of the properties of the samples of Sample Nos. 6 and 7, it was confirmed that in the case of the sample of Sample No. 7 having the immersion time in water of 48 h, a barium titanate-based dielectric material powder having BaCO ₃ /BaO≧0.55 was obtained.

On the other hand, in the case of the sample of sample No. 6 having the immersion time in water of 1 h, BaC0 ₃ /BaO=0.49 was low, so that the preferred barium titanate-based dielectric material powder could not be obtained.

In addition, when a multilayer ceramic capacitor was fabricated using the barium titanate-based dielectric material powder of Sample No. 7, the number of failures in the high temperature load life test was 0, which is highly reliable under high temperature load conditions, and the change rate of the capacitance is -20.8%. It was confirmed that a multilayer ceramic capacitor having good furnace temperature characteristics (X7S characteristics) was obtained.

On the other hand, when a multilayer ceramic capacitor was manufactured using the barium titanate-based dielectric material powder of Sample No. 6 having the immersion time in water of 1 h, the number of failures in the high temperature load life test was 19, which was low in reliability under high temperature load conditions. It was also confirmed that the rate of change in capacitance was also -27.3%, which is not preferable.

[About Samples of Sample Nos. 8 and 9]

The barium titanate-based dielectric material powders of Sample Nos. 8 and 9 in Table 1 are barium titanate-based dielectric material powders prepared by changing the immersion time into 1h and 48h using BaTi0 ₃ having an average primary particle diameter of 340 nm. .

From the results of the measurement of the characteristics of the samples of Sample Nos. 8 and 9, it was confirmed that in the case of the Sample No. 9 having the immersion time in water of 48 h, a barium titanate-based dielectric material powder having BaCO ₃ /BaO≧0.55 was obtained.

On the other hand, in the case of the sample of Sample No. 8 having the immersion time in water of 1 h, BaCO ₃ /BaO=0.50 was low, and thus, the preferred barium titanate-based dielectric material powder could not be obtained.

In the case of the multilayer ceramic capacitor fabricated using the barium titanate-based dielectric material powder of Sample No. 9, the number of failures in the high temperature load life test is 0, and the rate of change in capacitance is -14.7%, which is a good temperature characteristic (X7S Characteristics) were obtained.

On the other hand, when the multilayer ceramic capacitor was manufactured using the barium titanate-based dielectric material powder of Sample No. 8 having the immersion time in water for 1 h, the change rate of the capacitance was -18.6% and the temperature characteristic (X7S characteristic) was good. In the high temperature load life test, the number of failures was 50, and it was confirmed that the reliability under the high temperature load condition was low.

[Example 2]

BaCO ₃ and Ti0 ₂ were prepared as starting materials, and weighed and blended so that the ratio of Ba and Ti was Ba / Ti = 1.000 (at ratio). Then, this blended raw material was mixed by a ball mill (using a PSZ media having a diameter of 2 mm) and heat-treated at 1000 ° C. in the air to synthesize barium titanate represented by the general formula BaTiO ₃ .

The barium titanate powder (BaTiO ₃ powder) having an average primary particle diameter of 150 nm was obtained by pulverizing the barium titanate.

Moreover, BaZr0 ₃ , BaC0 ₃ , Gd ₂ 0 ₃ , Dy ₂ 0 ₃ , MnCO ₃ , MgCO ₃ , Si0 ₂ were prepared as additional components.

And, with respect to the average primary particle size of the barium titanate powder 150㎚ (BaTi0 ₃ powder) 100g prepared as above described, of the additional component _{group, BaZrO 3, BaCO 3, Gd} 2 0 3, Dy 2 0 3, MnCO _3, MgCO ₃ were prepared, each sample of sample numbers 10 to 13 of Si0 blended at a ratio higher than the additive component is selected from _2, and Table 2 (barium titanate-based dielectric material powder).

That is, in Sample Nos. 10 and 11, an additive component is added to 100 g of barium titanate powder (BaTiO ₃ powder) having an average primary particle diameter of 150 nm,

BaTiO ₃ : 100mol

BaCO ₃ : 1mol

Dy ₂ O ₃ : 2mol

MnCO ₃ : 1mol

MgCO ₃ : 1.5mol

SiO ₂ : 1.5mol

The raw material of the composition A added so that it may become the ratio of is put into the beaker with 100 g of water, and the beaker is not sealed (exposed to air), and it is a screw-type stirrer, for 1 hour (sample number) as shown in Table 2. 10) or 48 hours (Sample No. 11).

And the obtained slurry was grind | pulverized for 1 hour by the forced circulation type grinder (using PSZ media of diameter 0.3mm). The obtained slurry was put into an oven at 140 ° C. within 15 minutes after completion of grinding to obtain a barium titanate-based dielectric material powder (samples 10 and 11 samples).

In addition, in sample numbers 12 and 13, the additive component is added to 100 g of barium titanate powder (BaTi0 ₃ powder) having an average primary particle diameter of 150 nm.

BaTi0 ₃ : 100mol

BaZrO ₃ : 9mol

BaCO ₃ : 2mol

Gd ₂ 0 ₃ : 4mol

Dy ₂ 0 ₃ : 0.5mol

MnC0 ₃ : 1mol

MgC0 ₃ : 3mol

SiO ₂ : 3mol

The raw material of the composition B added so that it may become a ratio of 100 g of water was put into a beaker, and the beaker was not sealed (exposed to air), and it was a screw-type stirrer for 1 hour as shown in Table 2 (sample number 12) or 48 hours (Sample No. 13).

And the obtained slurry was grind | pulverized for 1 hour by the forced circulation type grinder (using PSZ media of diameter 0.3mm). The obtained slurry was put into 140 degreeC oven within 15 minutes after completion | finish of grinding | pulverization, and the barium titanate type dielectric raw material powder (sample No. 12, 13) was obtained.

Then, using a part of the barium titanate-based dielectric material powders of Sample Nos. 10 to 13, the analysis was carried out by XPS. For samples Nos. 10 and 11 of the composition A, the Ba / Ti ratio of the raw material surface was determined. About the samples of the sample numbers 12 and 13 of the composition B, the Ba / (Ti + Zr) ratio was measured, and the BaC0 ₃ / BaO ratio was measured about each sample of the sample numbers 10-13. The results are shown in Table 2.

Next, to the barium titanate-based dielectric material powder prepared as described above, an organic solvent such as a polyvinyl butyral binder and ethanol was added to the barium titanate-based dielectric material powder prepared as described above, and wet-mixed by a ball mill to form a green sheet. A ceramic slurry was produced.

Thereafter, the multilayer ceramic capacitors (samples) of Sample Nos. 10 to 13 were produced under the same method and conditions as in Example 1, and the characteristics were evaluated.

The results are shown in Table 2. In addition, in Table 2, the sample with * attached to the sample number is a sample outside the scope of the present invention.

[About Samples of Sample Nos. 10 and 11]

The barium titanate-based dielectric material powders of Sample Nos. 10 and 11 in Table 2 were prepared by changing the immersion time into water at 1h and 48h using a raw material powder of composition A containing BaTi0 ₃ and an additive component. It is a raw powder.

From the measurement results of the samples of the samples Nos. 10 and 11, it was confirmed that the barium titanate-based dielectric material powder of BaCO ₃ /BaO≧0.55 was obtained by setting the immersion time to 48 h as in sample No. 11.

On the other hand, in the case of the sample of Sample No. 10 having the immersion time in water of 1 h, BaCO ₃ /BaO=0.50 was low, and thus the preferred barium titanate-based dielectric material powder could not be obtained.

In the case of the multilayer ceramic capacitor fabricated using the barium titanate-based dielectric material powder having the immersion time of the sample number 11 set to 48 h in the samples of the sample numbers 10 and 11, the number of failures in the high temperature load life test is zero, and the power failure It was confirmed that favorable temperature characteristics (X7S characteristics) were obtained at a rate of change of capacity of -18.4%.

On the other hand, when the multilayer ceramic capacitor was manufactured using the barium titanate-based dielectric material powder of sample No. 10 having the immersion time in water for 1 h, the number of failures in the high temperature load life test was 39, which was low in reliability under high temperature load conditions. It was also confirmed that the rate of change in capacitance was also -22.8%, which is not preferable.

[About Samples of Sample Nos. 12 and 13]

The barium titanate-based dielectric material powders of Sample Nos. 12 and 13 in Table 2 were prepared by changing the immersion time in water to 1h and 48h using a raw material powder of composition B containing BaTi0 ₃ and an additive component. It is a raw powder.

From the results of the measurement of the characteristics of the samples of the samples Nos. 12 and 13, it was confirmed that in the case of the sample of No. 13 having the immersion time in water of 48 h, a barium titanate-based dielectric material powder having BaCO ₃ /BaO≧0.55 was obtained.

On the other hand, in the case of the sample of sample No. 12 having the immersion time in water of 1 h, BaC0 ₃ /BaO=0.51 was low, so that a preferable barium titanate-based dielectric material powder could not be obtained.

In addition, in the case of the multilayer ceramic capacitor fabricated using the barium titanate-based dielectric material powder of Sample No. 13, the number of failures in the high temperature load life test was 0, and the change rate of the capacitance was -20.9%, which is good temperature characteristics (X7S characteristics). Was obtained.

On the other hand, when the multilayer ceramic capacitor was manufactured using the barium titanate-based dielectric material powder of sample No. 12 having the immersion time in water for 1 h, the failure count in the high temperature load life test was 28, which was low in reliability under high temperature load conditions. It was also confirmed that the rate of change of the capacitance was also -23.7%, which is not preferable.

From the results of the above examples, according to the method of the present invention, by using the barium titanate-based dielectric material powder satisfying the requirements of BaCO ₃ /BaO≧0.55, and using the barium titanate-based dielectric material powder, the temperature characteristic of dielectric constant is improved. While flattening, it was confirmed that a multilayer ceramic capacitor having excellent reliability in a high temperature high field at the time of load testing or the like was obtained.

In Examples 1 and 2, a ceramic green sheet is manufactured by using the barium titanate-based dielectric material powder prepared by applying the present invention, and a multilayer ceramic capacitor is manufactured by using the obtained ceramic green sheet as an example. However, the barium titanate-based dielectric material powder produced according to the present invention is not limited to a multilayer ceramic capacitor but can be applied to LC composite parts, PTC thermistors and the like.

In Examples 1 and 2, water is used as the aqueous solvent in which the BaTiO ₃ powder is immersed. The aqueous solvent is not limited to this, but an organic solvent is added to water, and a trace amount for improving the dispersant and the characteristics. It is possible to use a variety of aqueous solvents containing water as the main component, such as adding an additional component.

The present invention is not limited to Examples 1 and 2 in other respects as well, and the temperature and agitation conditions when the BaTi0 ₃ powder is immersed in an aqueous solvent, using the barium titanate-based dielectric material powder of the present invention It is possible to add various applications and modifications within the scope of the invention with respect to specific conditions in the case of forming the ceramic green sheet, the order and conditions when manufacturing the multilayer ceramic capacitor using the ceramic green sheet, and the like.

1: ceramic element (capacitor element) 2a, 2b: internal electrode
3: ceramic layer 4a, 4b: external electrode
t: element film (thickness of ceramic layer)

Claims (6)

A barium titanate-based dielectric material powder, wherein a surface of a BaTi0 ₃ powder is coated with a barium compound having a BaC0 ₃ /BaO=0.55 ratio in a molar ratio of BaC0 ₃ and BaO. The method of claim 1,
A barium titanate-based dielectric material powder containing an additive component for adjusting properties. Preparing a BaTiO ₃ powder,
16. The method of manufacturing the barium titanate-based dielectric material powder, wherein the BaTiO ₃ powder is immersed in an aqueous solvent for at least 16 hours. The method of claim 3,
A method for producing a barium titanate-based dielectric material powder, wherein BaTiO ₃ powder to which an additive component for adjusting properties is added is used as the BaTiO ₃ powder. A process for preparing a slurry for sheet molding containing the barium titanate-based dielectric material powder according to claim 1 or 2, a binder, and a dispersion medium;
And forming the ceramic green sheet by molding the sheet forming slurry into a sheet. Forming an internal electrode pattern by applying a conductive paste to the ceramic green sheet formed by the method of claim 5;
Stacking and compressing the ceramic green sheets on which the internal electrode patterns are formed to form a laminate;
And firing the laminate to obtain a ceramic capacitor device having a structure in which internal electrodes are laminated through a ceramic layer.

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