JP2003100544A - Porcelain capacitor and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the following problem that, recently, demands for the improvement of the performance of electronic equipment limitlessly increase and, accordingly, demands for the electric characteristics of electronic parts become increasingly strict and, in addition, demands for the electric characteristics of porcelain capacitors also become increasingly strict and, particularly, porcelain capacitors having better temperature characteristics and life characteristics are demanded. SOLUTION: In a porcelain capacitor, a dielectric layer is formed of two or more kinds of ceramic particles containing different kinds of component elements or containing identical component elements at different concentrations. The component elements may have concentration gradients between internal electrodes, or the elements may have such concentration gradients that the concentrations become higher as becoming closer to the internal electrodes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic capacitor having excellent temperature characteristics and life characteristics and a method for manufacturing the same.

[0002]

2. Description of the Related Art Generally, a porcelain capacitor comprises a chip-shaped element body and a pair of electrodes formed on both sides of the element body. In the case of a laminated type ceramic capacitor, the element body is generally composed of a laminated body in which a plurality of dielectric layers and internal electrodes are alternately laminated. Among the internal electrodes, adjacent internal electrodes face each other via a dielectric layer and are electrically connected to different external electrodes.

Here, as the dielectric layer, for example, a dielectric ceramic composition having barium titanate zirconate {Ba (TiZr) O ₃ } as a main component and a rare earth element added thereto and having reduction resistance is used. Is used. Further, as the internal electrodes, for example, one obtained by sintering a conductive paste containing Ni metal powder as a main component is used.

After debinding the chip-shaped laminated body in which the ceramic green sheets and the internal electrode patterns are alternately laminated integrally, the element body is heated at a high temperature of about 1200 to 1300 ° C. in a non-oxidizing atmosphere. It is manufactured by firing and then reoxidizing it in a weakly oxidizing atmosphere.

[0005]

By the way, in order to improve the performance of electronic equipment, a ceramic capacitor having good temperature characteristics and life characteristics is required, and therefore various ceramic capacitors have been proposed.

However, in recent years, the demands for improving the performance of electronic devices are not limited, and therefore, the demands for the electrical characteristics of electronic parts are more and more strict, and the demands for the electrical properties of porcelain capacitors are also increasing. There are some strict requirements, and in particular, those with even better temperature characteristics and life characteristics are required.

It is an object of the present invention to provide a porcelain capacitor having excellent temperature characteristics and life characteristics and a method for manufacturing the same.

[0008]

A ceramic capacitor according to the present invention comprises a dielectric layer made of a dielectric ceramic composition, an internal electrode sandwiching the dielectric layer, and an electrical connection to the internal electrode. And a dielectric ceramic composition, wherein the dielectric ceramic composition is composed of two or more kinds of ceramic particles having different concentrations of predetermined constituent elements.

Here, the predetermined component element may have a concentration gradient between the internal electrodes. Here, having a concentration gradient with respect to a predetermined component element means that the concentration of the predetermined component element continuously increases or decreases as it approaches or moves away from the internal electrode. Further, with respect to a certain ceramic particle, the concentration of another component element may decrease as the concentration of a specific component element increases, or vice versa. Further, the concentration of the predetermined component element in the ceramic particles may be uniform, or may have a concentration gradient in the vicinity of the surface and inside.

The predetermined constituent elements are Ba, Ti, Zr,
Rare earth elements, Mn, Si, Cr, V, Co, Mo and W
One or two or more selected from the above can be listed, but any other element may be used as long as the life characteristics of the porcelain capacitor can be improved.

Further, the method of manufacturing a porcelain capacitor according to the present invention comprises, as basic steps, a ceramic raw material adjusting step of adjusting a ceramic raw material, a sheet forming step of forming a ceramic green sheet using the ceramic raw material,
A printing step of printing an internal electrode pattern made of a conductive paste on the ceramic green sheet, a stacking step of stacking the ceramic green sheets printed with the internal electrode pattern to obtain a laminate, and the stack for each internal electrode pattern. Cutting step to obtain a chip-shaped laminated body by cutting into a chip, a firing step of firing the chip-shaped laminated body in a non-oxidizing atmosphere, and a firing of the laminated body after the firing step in a weakly oxidizing atmosphere. And a reoxidation step of

In the method for manufacturing a porcelain capacitor according to the present invention, the raw material preparing step is an additive component powder obtained by calcining two or more kinds of compounds, for example, Ho ₂ O ₃ and Mn ₃ O ₄ . And a step of mixing the main component powder having ferroelectricity with the additive component powder, another manufacturing method of a porcelain capacitor is characterized in that the raw material preparing step is two types having ferroelectricity. The above main component powder, for example, BaTiO 3.
No. ₃ and BaZrO ₃ are mixed, and the method for manufacturing a porcelain capacitor according to still another embodiment of the present invention is such that the conductive paste contains component elements, and the component elements are Ba, Ti, Z.
It is characterized by comprising one or more selected from r, rare earth elements, Mn, Si, Cr, V, Co, Mo and W.

[0013]

EXAMPLES Example 1: First, BaTi _0.854 Zr _0.146
O ₃ powder was synthesized and crushed with a pot mill to give a particle size D
A main component powder of 50 (%) = 0.55 μm was obtained. Also,
29.6 g of Ho ₂ O ₃ and 9.6 g of Mn ₃ O ₄ were weighed and put in a pot mill together with beads, stirred and mixed by a wet method, and the resulting slurry was taken out and dried. It was calcined at ℃ for 2 hours to obtain a Ho-Mn calcined product. Next, this Ho-Mn calcined product is put into a pot mill together with beads and pulverized by a dry method to obtain a particle size D50.
(%) = 1.5 μm of additive component powder was obtained.

Next, the main component {BaTi _0.854 Zr _0.146 O
₃ } powder, 1.26 g of SiO ₂ was added to 500 g, and these were put in a pot mill together with ZrO ₂ beads, stirred and mixed by a wet method, and when the particle size D50 (%) reached 0.46 μm, the addition prepared in advance 3.92 g of the component (Ho-Mn calcined product) powder was added, stirred and mixed for 1 hour, and the obtained slurry was taken out and dried to obtain a dielectric material powder. The particle size D50 (%) of each powder was measured by a laser diffraction particle size distribution meter.

Next, 1000 g (1
(00 parts by weight), 15% by weight of an organic binder composed of an aqueous solution of an acrylic ester polymer, glycerin, and a condensed phosphate is added, and further 50% by weight of water is added. To make a slurry.

Next, this slurry was put into a vacuum defoaming machine to defoam, and then put into a reverse roll coater to form a thin film of this slurry on the polyester film.
Then, this thin film is placed on a polyester film at 100 ° C.
Heat to dry and punch out, thickness about 5μm, 10
A square green sheet of cm × 10 cm was obtained.

On the other hand, 10 g of nickel powder having an average particle size of 0.5 μm and 0.9 g of ethyl cellulose dissolved in 9.1 g of butyl carbitol were placed in a stirrer, and 1
After stirring for 0 hour, a conductive paste for internal electrodes was obtained.
Then, a conductive pattern made of this conductive paste was printed on the green sheet and dried.

Next, 11 green sheets were laminated with the printed surface of the conductive pattern facing up. At this time, the adjacent upper and lower sheets were arranged such that their printing surfaces were displaced by about half in the longitudinal direction of the pattern. Further, green sheets on which conductive patterns were not printed were laminated on the upper and lower surfaces of this laminate.

Next, this laminate is pressure-bonded at a temperature of about 50 ° C. in the thickness direction by about 40 tons, and thereafter, the laminate is cut into a lattice shape, and the length is 4.0 mm × width 2 0.0 m
m laminated chips were obtained.

Next, a Ni external electrode is formed by dipping on the end face of the laminated chip from which the internal electrode is exposed, and the laminated chip is placed in a furnace capable of atmospheric firing and heated in an N ₂ atmosphere to remove the organic binder. The oxygen partial pressure is 10
1260 ° C to 136 under the condition of ^-5 to 10 ^-10 atm.
Baking at 0 ° C. for 1 to 5 hours, then under N ₂ atmosphere, 60
Reoxidation treatment was performed at 0 to 800 ° C. to obtain a laminated ceramic capacitor.

Next, TEM is performed on 30 to 50 ceramic particles forming the dielectric layer of the laminated ceramic capacitor.
-EDS was used to analyze the component composition, and the results were classified into three types (particles A, B, and C) by paying attention to the concentrations of Ho and Mn, and as shown in the column of Example 1 in Table 1. became. The composition ratio of particle A / particle B / particle C is 35/26 /
It was 39.

It is considered that this dielectric layer has a fine structure as shown in FIG. The composition values shown in Table 1 were obtained by three-point analysis of one ceramic particle.
It is the average value of the individual composition values.

Next, the electrical characteristics of the obtained laminated ceramic capacitor were measured, and the results were as shown in Table 2.

The electrical characteristics were measured as follows.

(A) The relative permittivity ε is a temperature of 20 ° C. and a frequency of 1
Capacitance was measured under the condition of kHz and voltage (effective value) of 1.0 V, and calculated from the measured value, the facing area of the pair of internal electrodes 14, and the thickness of the dielectric ceramic layer between the pair of internal electrodes. I asked for.

(B) Dielectric loss tan δ (%) was measured under the same conditions as in the above-mentioned measurement of relative permittivity.

(C) The capacity change rate ΔC (%) was measured by placing the sample in a constant temperature bath and statically at a temperature of -25 ° C and + 85 ° C at a frequency of 1 kHz and a voltage (effective value) of 1.0 V. It was obtained by measuring the capacitance and determining the rate of change of the capacitance with respect to the capacitance of 20 ° C.

(D) Accelerated life (sec) is 150 ° C / 2
Insulation resistivity (ρ) is 1 × 1 under 0V / μm DC electric field
It was obtained by measuring the time to reach 0 ¹⁰ Ωcm.

Example 2: First, BaTiO ₃ and BaZ
rO ₃ was synthesized, and each was crushed to obtain a particle size D50.
(%) = 0.52 μm BaTiO ₃ and particle size D50
(%) = 0.65 μm of BaZrO ₃ was formed.

Next, BaTiO 3_Three229.45g, Ba
ZrO_Three270.55g, Ho_TwoO _Three2.96 g, Si
O_Two1.26 g, Mn_ThreeO_FourWeigh 0.96g, this
ZrO_TwoPut the beads in a pot mill together with the beads, and the particle size D
Stir and mix by wet method until 50 (%) = 0.48 μm
Then, the obtained slurry is taken out and dried, and the dielectric material
A raw powder was obtained.

Next, a laminated ceramic capacitor was prepared in the same manner as in Example 1, and 30 to 50 ceramic particles forming the dielectric layer were analyzed for component composition using TEM-EDS. Pay attention to the concentration of Ti and Zr 3
The results are shown in Table 1 when the particles (particles D, E, F) are classified. The composition ratio of the particles D, the particles E, and the particles F was 29/40/31. It is considered that this dielectric layer also has a fine structure as shown in FIG. However, in FIG. 1, particle A is replaced with particle D, particle B is replaced with particle E, and particle C is replaced with particle F.

Next, the electrical characteristics of the obtained laminated ceramic capacitor were measured in the same manner as in Example 1, and the results are shown in Table 2.

Comparative Example 1: BaT which was previously synthesized and crushed
i _0.854 Zr _0.146 O ₃ {D50 (%) = 0.53 μm}
Ho ₂ O ₃ 2.96 g, SiO ₂ 1.26 in 500 g.
g, Mn ₃ O ₄ 0.96 g was added, and these were added to ZrO ₂
Put in beads in a pot mill, stir and mix by wet method, stir until particle size D50 (%) = 0.45 μm
After mixing, the resulting slurry was taken out and dried to obtain a dielectric material powder.

Next, a laminated ceramic capacitor was prepared in the same manner as in Example 1, and 30 to 50 ceramic particles forming the dielectric layer were analyzed for composition by TEM-EDS. Comparative Example 1 was obtained. It is considered that the fine structure of this dielectric layer is as shown in FIG.

Next, the electrical characteristics of the obtained laminated ceramic capacitor were measured in the same manner as in Example 1, and the results are shown in Table 2.

Example 3 Pre-synthesized and crushed BaT
i _0.854 Zr _0.146 O ₃ {D50 (%) = 0.53 μm}
Ho ₂ O ₃ 2.96 g, SiO ₂ 1.26 in 500 g.
g, Mn ₃ O ₄ 0.96 g was added, and these were added to ZrO ₂
Put in beads in a pot mill, stir and mix by wet method, stir until particle size D50 (%) = 0.45 μm
After mixing, the resulting slurry was taken out and dried to obtain a dielectric material powder. Then, a green sheet was formed in the same manner as in Example 1.

On the other hand, 10 g of nickel powder having an average particle size of 0.5 μm, 0.9 g of ethyl cellulose dissolved in 9.1 g of butyl carbitol, and 2.5 g of an additive material (sintering delay material) were stirred. And was stirred for 10 hours to obtain a conductive paste for internal electrodes. ZrO as an additive
₂ used a material 20 mol% more than the green sheet. Then, a conductive pattern made of this conductive paste was printed on the green sheet and dried.

Then, a laminated ceramic capacitor was prepared in the same manner as in Example 1, and 30 to 50 ceramic particles forming the dielectric layer were analyzed for composition by TEM-EDS. As shown in Example 3. The electrical characteristics of the obtained laminated ceramic capacitor were measured in the same manner as in Example 1, and the results are shown in Table 2. The fine structure of this dielectric layer is considered to have a fine structure as shown in FIG.

Example 4: Pre-synthesized and crushed BaT
i _0.854 Zr _0.146 O ₃ {D50 (%) = 0.53 μm}
Ho ₂ O ₃ 2.96 g, SiO ₂ 1.26 in 500 g.
g, Mn ₃ O ₄ 0.96 g was added, and these were added to ZrO ₂
Put the beads in a pot mill, stir and mix them in a wet manner, and stir until the particle size D50 (%) becomes 0.45 μm.
After mixing, the resulting slurry was taken out and dried to obtain a dielectric material powder. Then, a green sheet was formed in the same manner as in Example 1.

On the other hand, 10 g of nickel powder having an average particle size of 0.5 μm, 0.9 g of ethyl cellulose dissolved in 9.1 g of butyl carbitol, and 2.5 g of an additive material (sinter retarder) were stirred. And was stirred for 10 hours to obtain a conductive paste for internal electrodes. Mn ₃ as an additive
A material in which O ₄ is 2 atomic% higher than that of the green sheet was used. Then, a conductive pattern made of this conductive paste was printed on the green sheet and dried.

Then, a laminated ceramic capacitor was prepared in the same manner as in Example 1, and 30 to 50 ceramic particles forming the dielectric layer were analyzed for composition by TEM-EDS. Came to show. The electrical characteristics of the obtained laminated ceramic capacitor were measured in the same manner as in Example 1, and the results are shown in Table 2. It is considered that the fine structure of this dielectric layer also has a fine structure as shown in FIG. However, in FIG.
Particle H is particle K, particle I is particle L, particle J is particle M
Replace it with

Example 5: BaT pre-synthesized and crushed
i _0.854 Zr _0.146 O ₃ {D50 (%) = 0.53 μm}
Ho ₂ O ₃ 2.96 g, SiO ₂ 1.26 in 500 g.
g, Mn ₃ O ₄ 0.96 g was added, and these were added to ZrO ₂
Put in beads in a pot mill, stir and mix by wet method, stir until particle size D50 (%) = 0.45 μm
After mixing, the resulting slurry was taken out and dried to obtain a dielectric material powder. Then, a green sheet was formed in the same manner as in Example 1.

On the other hand, 10 g of nickel powder having an average particle size of 0.5 μm, 0.9 g of ethyl cellulose dissolved in 9.1 g of butyl carbitol, and 2.5 g of an additive material (sintering delay material) were stirred. And was stirred for 10 hours to obtain a conductive paste for internal electrodes. As an additive material, Mn,
A material in which Cr, Co, and V are 2 atomic% more than the above green sheet was used. Then, a conductive pattern made of this conductive paste was printed on the green sheet and dried.

Then, a laminated ceramic capacitor was prepared in the same manner as in Example 1, and 30 to 50 ceramic particles forming the dielectric layer were analyzed for composition by TEM-EDS. Came to show. The electrical characteristics of the obtained laminated ceramic capacitor were measured in the same manner as in Example 1, and the results are shown in Table 2. It is considered that the fine structure of this dielectric layer also has a fine structure as shown in FIG. However, in FIG.
Particle H is particle N, particle I is particle O, particle J is particle P
Replace it with

Example 6: BaT pre-synthesized and crushed
i _0.854 Zr _0.146 O ₃ {D50 (%) = 0.53 μm}
Ho ₂ O ₃ 2.96 g, SiO ₂ 1.26 in 500 g.
g, Mn ₃ O ₄ 0.96 g was added, and these were added to ZrO ₂
Put the beads in a pot mill, stir and mix them in a wet manner, and stir until the particle size D50 (%) becomes 0.45 μm.
After mixing, the resulting slurry was taken out and dried to obtain a dielectric material powder. Then, a green sheet was formed in the same manner as in Example 1.

On the other hand, 10 g of nickel powder having an average particle size of 0.5 μm, 0.9 g of ethyl cellulose dissolved in 9.1 g of butyl carbitol, and 2.5 g of an additive material (sinter retarder) were stirred. And was stirred for 10 hours to obtain a conductive paste for internal electrodes. Sm as an additive,
A material in which Gd and Y were 2 atomic% higher than the above green sheet was used. Then, a conductive pattern made of this conductive paste was printed on the green sheet and dried.

Then, a laminated ceramic capacitor was prepared in the same manner as in Example 1, and 30 to 50 ceramic particles forming the dielectric layer were analyzed for composition by TEM-EDS. Came to show. The electrical characteristics of the obtained laminated ceramic capacitor were measured in the same manner as in Example 1, and the results are shown in Table 2. It is considered that the fine structure of this dielectric layer also has a fine structure as shown in FIG. However, in FIG.
Particle H is particle Q, particle I is particle R, particle J is particle S
Replace it with

Example 7: BaT previously synthesized and crushed
i _0.854 Zr _0.146 O ₃ {D50 (%) = 0.53 μm}
Ho ₂ O ₃ 2.96 g, SiO ₂ 1.26 in 500 g.
g, Mn ₃ O ₄ 0.96 g was added, and these were added to ZrO ₂
Put the beads in a pot mill, stir and mix them in a wet manner, and stir until the particle size D50 (%) becomes 0.45 μm.
After mixing, the resulting slurry was taken out and dried to obtain a dielectric material powder. Then, a green sheet was formed in the same manner as in Example 1.

On the other hand, 10 g of nickel powder having an average particle diameter of 0.5 μm, 0.9 g of ethyl cellulose dissolved in 9.1 g of butyl carbitol, and 2.5 g of an additive material (sintering delay material) were stirred. And was stirred for 10 hours to obtain a conductive paste for internal electrodes. Mo as an additive material,
A material in which W is 2 atomic% higher than that of the green sheet was used. Then, a conductive pattern made of this conductive paste was printed on the green sheet and dried.

Then, a laminated ceramic capacitor was prepared in the same manner as in Example 1, and 30 to 50 ceramic particles forming the dielectric layer were analyzed for composition by TEM-EDS. Came to show. The electrical characteristics of the obtained laminated ceramic capacitor were measured in the same manner as in Example 1, and the results are shown in Table 2. It is considered that the fine structure of this dielectric layer also has a fine structure as shown in FIG. However, in FIG.
Particle H is particle T, particle I is particle U, particle J is particle V
Replace it with

[0051]

[Table 1]

[0052]

[Table 2]

From Tables 1 and 2, it is understood that when the dielectric ceramic composition forming the dielectric layer is composed of particles having different component compositions, the life characteristics of the ceramic capacitor are improved.

[0054]

According to the present invention, there is an effect that it is possible to obtain a porcelain capacitor having good electric characteristics, particularly excellent life characteristics.

[Brief description of drawings]

FIG. 1 is an explanatory view schematically showing a fine structure of a dielectric layer according to Examples 1 and 2.

FIG. 2 is an explanatory view schematically showing the fine structure of dielectric layers according to Examples 3 to 7.

FIG. 3 is an explanatory view schematically showing a fine structure of a dielectric layer according to Comparative Example 1.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C04B 35/495 C04B 35/00 JF term (reference) 4G030 AA10 AA11 AA16 AA17 AA19 AA22 AA23 AA24 AA25 AA28 AA37 AA61 BA09 CA03 CA08 GA19 GA24 GA34 4G031 AA06 AA07 AA11 AA12 AA13 AA16 AA17 AA18 AA19 AA22 AA30 AA39 BA09 CA03 CA08 GA08 GA17 5E001 AB03 AE02 AH01 AH09 AJ01 AJ02

Claims (7)

[Claims] 1. A dielectric layer made of a dielectric ceramic composition,
Two or more kinds of internal electrodes sandwiching the dielectric layer and external electrodes electrically connected to the internal electrode, wherein the dielectric ceramic composition has different concentrations of predetermined constituent elements. A porcelain capacitor characterized by comprising ceramic particles of. 2. The ceramic capacitor according to claim 1, wherein the predetermined component element has a concentration gradient between the internal electrodes. 3. The porcelain capacitor according to claim 2, wherein the predetermined component element has a concentration gradient such that the concentration is higher as the ceramic particles are closer to the internal electrodes. 4. The predetermined constituent element is Ba, Ti, Z
The porcelain capacitor according to any one of claims 1 to 3, which is composed of one or more selected from r, rare earth elements, Mn, Si, Cr, V, Co, Mo and W. 5. A ceramic raw material adjusting step of adjusting a ceramic raw material, a sheet forming step of forming a ceramic green sheet using the ceramic raw material, and a printing step of printing an internal electrode pattern made of a conductive paste on the ceramic green sheet. A step of laminating ceramic green sheets printed with the internal electrode patterns to obtain a laminate, a step of cutting the laminate for each internal electrode pattern to obtain a chip-like laminate, and a step of cutting the chips. And a reoxidation step of firing the laminated body that has undergone the firing step in an oxidizing atmosphere, wherein the raw material preparation step comprises two or more compounds. Calcination to form an additive component powder, and a step of mixing the ferroelectric component main component powder with the additive component powder. Manufacturing method of porcelain capacitor. 6. A ceramic raw material adjusting step of adjusting a ceramic raw material, a sheet forming step of forming a ceramic green sheet using the ceramic raw material, and a printing step of printing an internal electrode pattern made of a conductive paste on the ceramic green sheet. A step of laminating ceramic green sheets printed with the internal electrode patterns to obtain a laminate, a step of cutting the laminate for each internal electrode pattern to obtain a chip-like laminate, and a step of cutting the chips. And a re-oxidation step of firing the laminated body that has undergone the firing step in an oxidizing atmosphere, and the raw material preparation step has ferroelectricity. A method of manufacturing a porcelain capacitor, comprising a step of mixing two or more kinds of main component powders. 7. A ceramic raw material adjusting step of adjusting a ceramic raw material, a sheet forming step of forming a ceramic green sheet using the ceramic raw material, and a printing step of printing an internal electrode pattern made of a conductive paste on the ceramic green sheet. A step of laminating ceramic green sheets printed with the internal electrode patterns to obtain a laminate, a step of cutting the laminate for each internal electrode pattern to obtain a chip-like laminate, and a step of cutting the chips. And a reoxidation step of firing the laminated body that has undergone the firing step in an oxidizing atmosphere. The conductive paste is made of Ba, Ti, Zr, Porcelain condensate containing one or more elements selected from rare earth elements, Mn, Si, Cr, V, Co, Mo and W Manufacturing method of service.