JPH097880A - Laminated ceramic capacitor and manufacture thereof - Google Patents

Abstract

PURPOSE: To enable a laminated ceramic capacitor to be prevented from deteriorating in characteristics in a manufacturing process and lessened in cost by a method wherein the main component and auxiliary component of a dielectric ceramic layer are lead composite perovskite compound and reduction inhibiting agent respectively, and inner electrodes are formed of nickel or nickel alloy. CONSTITUTION: A dielectric ceramic layer 1 comprises lead composite perovskite compound as a main component and reduction inhibiting agent as an auxiliary component. Inner electrodes are formed of nickel or nickel alloy. Reduction inhibiting agent is represented by a general formula, wherein MOx is one compound selected out of MnO2 , Li2 O, and ZnO, R is one element selected out of Mg, Sr, Ca, and Ba, and α, β, and γ are indicated in mol% and set so as to satisfy formulas, 5<=α<=20, 10<=β<=60, and 20<=γ<=.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art A multilayer ceramic capacitor has a plurality of dielectric ceramic layers and a plurality of internal electrodes formed between the respective dielectric ceramic layers, and external electrodes connected to these internal electrodes at both end faces of the dielectric ceramic layers. And electrodes.

Conventionally, as a material of the dielectric ceramic layer, for example, a material which becomes a lead-based composite perovskite type compound by firing is used for the purpose of obtaining a small size and a large capacity. Further, as the material of the internal electrodes, noble metals such as platinum and silver-palladium alloy, which have a high melting point and are hard to oxidize at high temperature, have been used.

A monolithic ceramic capacitor using these materials has generally been manufactured as follows. That is, first, after producing a ceramic green sheet containing a dielectric ceramic material, a thick film internal electrode paste layer is formed on this ceramic green sheet by screen printing or the like. After that, a predetermined number of ceramic green sheets having the internal electrode paste layer formed thereon are stacked and pressure-bonded, and then fired at a temperature of about 1000 ° C. in an air atmosphere to obtain a sintered body. Then, an external electrode such as silver is baked on the exposed portion of the internal electrode of the sintered body to obtain a monolithic ceramic capacitor.

[0005]

However, the use of noble metals such as platinum and silver-palladium alloys for the internal electrodes greatly hinders cost reduction of the monolithic ceramic capacitor because these materials are expensive. Was becoming. In addition, the characteristics of the internal electrode formed of a silver-palladium alloy may be deteriorated by the migration of silver, and the internal electrode formed of platinum has a low electrical conductivity, resulting in a large equivalent series resistance of the capacitor. I will end up.

Therefore, in order to solve the above problems,
The use of base metals such as high melting point nickel, cobalt, and tungsten can be considered. However, these base metals are easily oxidized in a high temperature oxidizing atmosphere and cannot serve as electrodes. Therefore, in order to use these base metals as the internal electrodes of the monolithic ceramic capacitor, it is necessary to fire them together with the dielectric material in a neutral or reducing atmosphere.

However, when the above-mentioned dielectric material containing a material which becomes a lead-based composite perovskite type compound as a main component by firing is fired in a neutral or reducing atmosphere, the dielectric material is reduced and the resulting dielectric ceramic is obtained. There is a problem that the insulation resistance of the layer is reduced.

Therefore, a main object of the present invention is to provide a low-cost monolithic ceramic capacitor which does not deteriorate in characteristics during production and a method for producing the monolithic ceramic capacitor.

[0009]

In order to achieve the above object, a laminated ceramic capacitor of the present invention comprises a plurality of dielectric ceramic layers, a plurality of internal electrodes arranged via the dielectric ceramic layers, and In a multilayer ceramic capacitor including an external electrode connected to an internal electrode, the dielectric ceramic layer is composed of a material containing a lead-based composite perovskite type compound as a main component and a reduction inhibitor as a sub-component, The internal electrode is characterized by being made of nickel or a nickel alloy.

The reducing agent is represented by the general formula: αMOx
+ ΒRO + γB ₂ O ₃ + (100-α-β-γ) SiO
₂ (where MOx is at least one selected from MnO ₂ , Li ₂ O and ZnO, R is Mg, Sr, Ca
And at least one selected from Ba, α, β and γ are mol%, and 5 ≦ α ≦ 20 and 10 ≦ β, respectively.
≦ 60, 20 ≦ γ ≦ 35).

Further, the internal electrodes are characterized by being made of nickel or nickel alloy formed by a thin film forming method.

Further, the method for producing a monolithic ceramic capacitor of the present invention comprises a ceramic green sheet made of a material containing a lead-based composite perovskite type compound as a main component by firing and a reduction inhibitor as a sub-component.
A nickel or nickel alloy layer is formed by a thin film forming method, the ceramic green sheets are laminated to form a laminated body, and then the laminated body is fired at high speed.

In the method of forming the nickel or nickel alloy layer on the ceramic green sheet by the thin film forming method, a metal film made of nickel or nickel alloy is formed on the resin film by the thin film forming method, and the metal film is formed into a photo film. After patterning by etching to form the internal electrodes, the metal film is transferred from the resin film having the metal film onto the ceramic green sheet.

Further, the thin film forming method is characterized by at least one of vapor deposition, sputtering and plating.

[0015]

The dielectric ceramic material is obtained by adding a reduction inhibitor to a material that becomes a lead-based composite perovskite type compound by firing, a nickel or nickel alloy layer is used as an internal electrode, and the oxygen partial pressure at 900 ° C. to 1100 ° C. 1
By rapid firing in a neutral or reducing atmosphere of 0 ⁻⁶ to 10 ⁻¹¹ MPa, a laminated ceramic capacitor can be obtained without deteriorating its characteristics.

Copper is known as a metal which can be sintered in a neutral atmosphere having an oxygen partial pressure of about 10 ^-7 MPa at around 1000 ° C. However, copper easily undergoes an oxidation reaction from a relatively low temperature, and when a multilayer ceramic capacitor is obtained by firing copper as an internal electrode, Cu / CuO
If the firing is carried out at an oxygen partial pressure higher than the equilibrium oxygen partial pressure of, the copper will diffuse into the dielectric ceramic layer during firing, which has the drawback of deteriorating the characteristics, and it is necessary to accurately control the atmosphere during firing. is there.

On the other hand, nickel is relatively unlikely to undergo an oxidation reaction, and when nickel is used as the internal electrode,
Even if firing is performed at an oxygen partial pressure higher than the equilibrium oxygen partial pressure of / NiO, the characteristics of the monolithic ceramic capacitor are unlikely to deteriorate at a high speed for a short time. In particular, when the nickel or nickel alloy internal electrode is formed by a metal film formed by a thin film forming method such as vapor deposition, sputtering or plating, the oxygen partial pressure is 1 at 900 ° C to 1100 ° C.
The characteristics of the monolithic ceramic capacitor are not deteriorated by firing in a neutral or reducing atmosphere of 0 ^-6 to 10 ^-11 MPa.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The laminated ceramic capacitor of the present invention and the method for manufacturing the same will be described below. FIG. 1 is a sectional view of an example of a monolithic ceramic capacitor obtained by the following examples. In the figure, reference numeral 1 is a dielectric ceramic layer containing a lead-based composite perovskite compound as a main component.
Reference numeral 2 is an internal electrode made of nickel or a nickel alloy, and 3 is an external electrode.

Next, a method for manufacturing the monolithic ceramic capacitor of the present invention will be described based on examples. Of the samples shown in Table 1, the laminated ceramic capacitors of sample numbers 1 to 13 were manufactured as follows.

That is, first, as the dielectric powder, 92 Pb
(Mg _1/3 Nb _2/3 ) O ₃ -2Pb (Zn _1/2 N
b _1/2 ) O ₃ -6PbTiO ₃ (mol%) so that a three-component composition is obtained, PbO, MgCO ₃ , Nb
₂ O ₅ , TiO ₂ and ZnO are weighed and ball milled to 1
The mixture was wet mixed for 6 hours to obtain a powder having a particle size of 1 μm or less. Next, this powder is put into a zirconia-like box and heated at 680 ° C to 7 ° C.
After calcination at 30 ° C. for 2 hours, coarse pulverization was performed so as to pass through a 200-mesh sieve, and firing was performed to obtain a dielectric powder that became a lead-based composite perovskite compound.

Further, αMOx + βRO + γB ₂ O ₃ + (1
00-α-β-γ) SiO ₂ (where MOx is Mn
At least one selected from O ₂ , Li ₂ O and ZnO, R is at least one selected from Mg, Sr, Ca and Ba, α, β and γ are mol%) In order to obtain the agent, oxide, carbonate or hydroxide of each component was prepared. Then, these were weighed so as to obtain the reduction inhibitor having the composition shown in Table 1, wet-mixed with a ball mill and pulverized to obtain a powder. Then, this powder was put into an alumina crucible, held at 1200 to 1500 ° C. for 1 hour to melt, and then rapidly cooled to vitrify. Then, it was pulverized to obtain a reduction inhibitor having an average particle size of 1 μm.

Next, the previously prepared dielectric powder and these reducing agents were mixed in the ratio shown in Table 1, polyvinyl butyral binder, ethanol and toluene were added and mixed in a ball mill for 16 hours to form a slurry. Obtained. Then, this slurry was formed into a sheet by a doctor blade method to obtain a ceramic green sheet.

On the other hand, a 1.0 μm nickel metal film was formed on the polyethylene terephthalate film by vapor deposition. Then, after coating the nickel metal film with a photoresist, patterning was performed by a photoetching method so as to form internal electrodes.

Next, the nickel metal film on this film is placed on the ceramic green sheet,
The film was placed on the ceramic green sheet, and the nickel metal film was transferred onto the ceramic green sheet by hot pressing. Then, a plurality of ceramic green sheets to which this metal film was transferred were laminated to obtain a laminated body.
Then, this laminate is heated to 300 ° C. in air to burn the organic binder, and then the oxygen partial pressure is 10 ⁻⁷ MP.
It was fired at the temperature shown in Table 1 in the atmosphere of H ₂ —N ₂ —H ₂ O gas of a. At this time, heat at a temperature rising rate of 6 ° C / min to 20 ° C / min until the maximum temperature is reached,
After holding for 30 minutes to 60 minutes, it was cooled to room temperature at a temperature decreasing rate of 6 ° C / minute to 20 ° C / minute.

Next, silver paste is applied to both end faces of the obtained sintered body and baked at 600 ° C. in a nitrogen atmosphere,
An outer electrode was formed that was electrically connected to the inner electrode.

In this way, the external dimensions are 0.8 mm in width.
× length 1.6 mm × thickness 0.8 mm, the thickness of the dielectric ceramic layer between the internal electrodes is 15 μm, the total number of effective dielectric ceramic layers is 20, and the area of the counter electrode per layer is 0.
A 45 mm ² monolithic ceramic capacitor was obtained (Sample Nos. 1 to 13).

[0027]

[Table 1]

A laminated ceramic capacitor of sample No. 14 shown in Table 1 was prepared as follows.

That is, using the same dielectric ceramic green sheet as in the case of the laminated ceramic capacitor of sample No. 7 described above, the metal film formed by the thin film forming method to be the internal electrodes is a nickel vapor deposition film with a thickness of 1.0 μm. Instead, a copper deposited film having a thickness of 0.1 μm was formed by vapor deposition, and then a nickel plated film having a thickness of 0.9 μm was formed by electroless plating. The others were the same as in the case of sample number 7 to produce a laminated ceramic capacitor (sample number 14).

A laminated ceramic capacitor of sample No. 15 shown in Table 1 was manufactured as follows.

That is, using the same laminated body as in the case of the laminated ceramic capacitor of Sample No. 7 described above, after heating to 300 ° C. in air to burn the organic binder, the oxygen partial pressure is 10 ⁻⁶ to 10 ^−11. Firing was performed at 1000 ° C. in an atmosphere composed of H ₂ —N ₂ —H ₂ O gas of MPa.
At this time, firing is performed by heating up to 1000 ° C. at a temperature rising rate of 3.0 ° C./min, holding at 1000 ° C. for 2 hours, and then 2.0 ° C.
It was performed by cooling to room temperature at a temperature decrease rate of / min (normal firing). Otherwise, a laminated ceramic capacitor was manufactured by the same method as in the case of sample number 7 (sample number 15).

Further, as a comparative example, the above sample No. 1
No reduction inhibitor was added to the same dielectric powder as in the case of the laminated ceramic capacitors Nos. 15 to 15 to prepare a laminated ceramic capacitor (Sample No. 16).

Further, 27.9Li ₂ O-7.4BaO-5.6CaO was added to the same dielectric powder as in the case of the laminated ceramic capacitors of Sample Nos. 1 to 15 without adding a reduction inhibitor.
-5.6SrO-44.5SiO ₂ -2.0TiO ₂ -
A low temperature sintering agent represented by 7.0CuO (mol%) was added to produce a laminated ceramic capacitor (Sample No. 1).
7).

Next, for these laminated ceramic capacitors, at a temperature of 25 ° C., a frequency of 1 kHz and a voltage of 1 V.
Capacitance and dielectric loss (tan δ) under rms condition
Was measured. Then, the dielectric constant (ε) was calculated from the obtained capacitance. Furthermore, the insulation resistance was measured by applying a series voltage of 25 V for 2 minutes. Table 1 shows the results.

As shown in Table 1, the present invention makes it possible to obtain a monolithic ceramic capacitor having a relatively high dielectric constant, a small dielectric loss, and a high insulation resistance. In the manufacturing method, when high speed firing is not performed, the dielectric loss tends to increase as shown in Sample No. 15.

The composition range of the reduction inhibitor is as follows:
General formula, αMOx + βRO + γB _{2 O3} + (100-α-
β-γ) SiO ₂ (where MOx is MnO ₂ , Li ₂ O
And at least one selected from ZnO, and R is M
at least 1 selected from g, Sr, Ca and Ba
Type, α, β, and γ are mol%), and α, β, and γ are 5 ≦ α ≦ 20, 10 ≦ β ≦ 60, and 20 ≦ γ ≦ 3, respectively.
It is preferably 5.

That is, as in sample No. 1, the MOx amount α is 5
When it is less than mol%, the sintering temperature becomes higher than 1000 ° C. and the dielectric loss becomes large. On the other hand, when the MOx amount α is more than 20 mol% as in Sample No. 13, delamination occurs, which is not preferable.

When the RO amount β is less than 10 mol% as in sample No. 2, the sintering temperature is higher than 1000 ° C., the dielectric loss is large and the insulation resistance is low.
On the other hand, when the RO amount β is more than 60 mol% as in the sample No. 12, the sintering temperature becomes high and the dielectric loss becomes large.

Further, as in the case of sample No. 3, the B ₂ O ₃ amount γ is 2
If it is less than 0 mol%, the sintering temperature is 1000 ° C.
, The dielectric loss is large, and the insulation resistance is low. On the other hand, as in Sample No. 11, the B ₂ O ₃ amount γ is 35
If it is more than mol%, delamination occurs, which is not preferable.

On the other hand, when the reduction inhibitor is not added, the characteristics as a capacitor cannot be obtained as shown in sample No. 16. When a low-temperature sintering agent is added instead of the reduction inhibitor, as shown in Sample No. 17, the dielectric loss increases and the insulation resistance decreases, so that the multilayer ceramic capacitor cannot be used.

The dielectric used in the present invention is not limited to the above embodiment. That is, for example, Pb
(Fe _2/3 W _1/3 ) O ₃ -PbZrO ₃ system, Pb (Fe
_{2/3 W 1/3) O 3 -PbZrO 3} -Pb (Mn 2/3 W
_1/3 ) O ₃ system, Pb (Mn _{1/3 N} b _2/3 ) O ₃ -Pb (M
g _1/2 W _1/2 ) O ₃ -PbTiO ₃ system, Pb (Mg _{1/3
Nb 2/3) O 3 -Pb (Cu} 1/2 W 1/2) O 3 -PbT
iO ₃ system, Pb (Mg _1/3 Nb _2/3 ) O ₃ -Pb (Cu
Similar effects can be obtained in a lead-based composite perovskite type compound such as _1/2 W _1/2 ) O ₃ -Pb (Fe _1/2 Nb _1/2 ) O ₃ system.

Further, as a thin film forming method for forming the internal electrodes, a sputtering method can be used in addition to the vapor deposition and plating shown in the above embodiment.

As the metal film to be the internal electrode, nickel or nickel alloy is mainly used. For example, as shown in Sample No. 14, nickel is deposited on a copper vapor deposition film which is alloyed with nickel. A metal film may be provided to form an internal electrode composed of a plurality of metal films. In this case, depending on the type and thickness of the metal film other than nickel, the conductivity, melting point,
In addition, the oxidizability may change. Therefore, the type and thickness of the metal film to be combined are defined by the composition of the dielectric powder and the reduction inhibitor, and further the application of the obtained laminated ceramic capacitor.

As the external electrode material, the same material as the internal electrode, silver, palladium, silver-palladium alloy or the like can be appropriately used. As a method of forming the same, paste baking, vapor deposition, sputtering, plating or the like can be appropriately used.

[0045]

As is clear from the above description, according to the present invention, the action of the reduction inhibitor does not reduce the dielectric resistance of the dielectric ceramic layer during firing, thereby lowering the insulation resistance of the ceramic. Further, by performing high-speed firing using nickel or a nickel alloy as the internal electrodes, the internal electrodes are not oxidized and the dielectric loss of the ceramic is not increased, so that the dielectric constant is not lowered.

Further, since nickel or nickel alloy is used as the material of the internal electrodes, characteristic deterioration due to migration of the internal electrodes can be suppressed.

Furthermore, cost reduction can be achieved by using nickel or nickel alloy, which is cheaper than the noble metal used conventionally, as the internal electrode and by performing high-speed firing.

Therefore, according to the present invention, it is possible to obtain a low-cost monolithic ceramic capacitor which is free from characteristic deterioration during manufacture.

[Brief description of drawings]

FIG. 1 is a sectional view of a monolithic ceramic capacitor showing an embodiment of the present invention.

[Explanation of symbols]

 1 Dielectric ceramic layer 2 Internal electrode 3 External electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukio Hamaji 2 26-10 Tenjin Tenjin, Nagaokakyo City, Kyoto Murata Manufacturing Co., Ltd.

Claims (7)

[Claims] 1. A multilayer ceramic capacitor comprising a plurality of dielectric ceramic layers, a plurality of internal electrodes arranged via the dielectric ceramic layers, and external electrodes connected to the internal electrodes, wherein the dielectric The ceramic layer is made of a material containing a lead-based composite perovskite type compound as a main component and a reduction inhibitor as a sub-component, and the internal electrodes are made of nickel or a nickel alloy. Capacitors. 2. The reducing agent is represented by the general formula: αMOx + βR
O + γB ₂ O ₃ + (100-α-β-γ) SiO ₂ (where MOx is at least one selected from MnO ₂ , Li ₂ O and ZnO, R is Mg, Sr, Ca and B
At least one selected from a, α, β, and γ is mol%, and 5 ≦ α ≦ 20 and 10 ≦ β ≦ 6, respectively.
0, 20 ≦ γ ≦ 35), The multilayer ceramic capacitor according to claim 1. 3. The internal electrode is formed by a thin film forming method,
3. The multilayer ceramic capacitor according to claim 1, which is nickel or a nickel alloy. 4. A nickel or nickel alloy layer is formed by a thin film forming method on a ceramic green sheet made of a material whose main component is a lead-based composite perovskite type compound by firing and which contains a reduction inhibitor as an accessory component. After that, the ceramic green sheets are laminated to form a laminated body, and then the laminated body is fired at high speed, which is a method for manufacturing a laminated ceramic capacitor. 5. The reducing agent is represented by the general formula: αMOx + βR
O + γB ₂ O ₃ + (100-α-β-γ) SiO ₂ (where MOx is at least one selected from MnO ₂ , Li ₂ O and ZnO, R is Mg, Sr, Ca and B
At least one selected from a, α, β, and γ is mol%, and 5 ≦ α ≦ 20 and 10 ≦ β ≦ 6, respectively.
0, 20 ≦ γ ≦ 35)). The method for manufacturing a multilayer ceramic capacitor according to claim 4, wherein 6. A method of forming a nickel or nickel alloy layer on a ceramic green sheet by a thin film forming method, wherein a metal film made of nickel or nickel alloy is formed on a resin film by the thin film forming method, and the metal film is formed as a photo film. The method for producing a monolithic ceramic capacitor according to claim 4, wherein the metal film is transferred from the resin film having the metal film onto the ceramic green sheet after patterning by etching to form the internal electrodes. . 7. The method of manufacturing a multilayer ceramic capacitor according to claim 4, wherein the thin film forming method is at least one of vapor deposition, sputtering and plating.