JPH10172858A - Laminated layer ceramics capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a capacitor wherein, being permissively of 3000 or above. the insulation resistance at room temperature and 125 deg.C is high, and temperature characteristics of capacitance meet characteristics of each standard while excellent in weather resistance. SOLUTION: The capacitor contains a main component 100mol which is represented by a composition formula (1-α-β-γ)(BaO)m .TiO2 +αM2 O3 +βRe2 O3 +γ(Mn1-x-y Nix Coy )O (where, M2 O3 is at least one kind selected among Sc2 O3 and Y2 O3 , Re2 O3 is at least one kind of molecule selected among Sm2 O3 and Eu2 O3 and the coefficients α, β, γ, m, x, y are 0.0025<=α+β<=0.025, 0<β<=0.0075, 0.0025<=γ<=0.05, γ/(α+β)<=4, 0<=×<1.0, 0<=y<1.0, 0<=x+y<1.0, 1.000<m<=1.035), with 0.05-5.0mol additives, as reduced to MgO, of magnesium oxide. In addition, while the sum of the main component and magnesium oxide being 100 weight part, 0.2-3.0 weight part of glass oxide of SiO2 -TiO2 -MO group (where, MO is one or more kind of oxide selected among BaO, CaO, SrO, MgO, ZnO, MnO) and contained as material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic capacitor used for electronic equipment, and more particularly to a multilayer ceramic capacitor having internal electrodes made of nickel or a nickel alloy.

[0002]

2. Description of the Related Art Conventionally, the manufacturing process of a multilayer ceramic capacitor is generally as follows. First,
A sheet-shaped dielectric ceramic material having its surface coated with an electrode material serving as an internal electrode is prepared. As the dielectric ceramic material, for example, a material mainly containing BaTiO ₃ is used. Next, a dielectric ceramic material in the form of a sheet coated with the electrode material is laminated and thermocompression-bonded, and the integrated material is placed in a natural atmosphere at 1250 to 1350.
By firing at ℃, a dielectric ceramic having internal electrodes is obtained. Then, an external electrode that is electrically connected to the internal electrode is baked on the end face of the dielectric ceramic, whereby a multilayer ceramic capacitor is obtained.

Therefore, the material of the internal electrode must satisfy the following conditions. (A) Since the dielectric ceramic and the internal electrode are fired at the same time, the dielectric ceramic has a melting point higher than the temperature at which the dielectric ceramic is fired. (B) It is not oxidized even in an oxidizing high-temperature atmosphere and does not react with the dielectric ceramic. Electrodes satisfying such conditions include platinum, gold,
Noble metals such as palladium or silver-palladium alloys have been used. However, while these electrode materials have excellent characteristics, they are expensive. Therefore, this has been the biggest factor in increasing the manufacturing cost of the multilayer ceramic capacitor.

[0004] In addition to noble metals, those having a high melting point
There are base metals such as i, Fe, Co, W, and Mo, but these base metals are easily oxidized in a high-temperature oxidizing atmosphere, and do not serve as an electrode.
Therefore, in order to use these base metals as the internal electrodes of the multilayer ceramic capacitor, it is necessary to fire them together with the dielectric ceramic in a neutral or reducing atmosphere. However, with conventional dielectric ceramic materials,
When sintering in such a neutral or reducing atmosphere, there is a drawback that the material is significantly reduced and turned into a semiconductor.

In order to overcome such disadvantages, for example, as disclosed in Japanese Patent Publication No. Sho 57-42588, a barium titanate solid solution having a barium site / titanium site ratio exceeding the stoichiometric ratio is used. As disclosed in Japanese Unexamined Patent Publication (Kokai) No. 61-101449, La, Nd, S
Dielectric ceramic materials to which rare earth oxides such as m, Dy, and Y are added have been proposed.

[0006] Further, as an example in which the temperature change of the dielectric constant is reduced, for example, the composition of BaTiO ₃ -CaZrO ₃ -MnO-MgO system disclosed in JP-A-62-256422 and JP-B-61-14611 are disclosed. Ba shown
TiO ₃ — (Mg, Zn, Sr, Ca) O—B ₂ O ₃ —S
Dielectric ceramic materials having an iO ₂ -based composition have been proposed.

By using such a dielectric ceramic material, a dielectric ceramic which does not turn into a semiconductor even when fired in a reducing atmosphere can be obtained, and a multilayer ceramic capacitor using a base metal such as nickel as an internal electrode can be obtained. Manufacturing has become possible.

[0008]

With the development of electronics in recent years, the miniaturization of electronic components has rapidly progressed, and the tendency of multilayer ceramic capacitors to be smaller and have a larger capacity has become remarkable. Therefore, the dielectric constant of the dielectric ceramic material and the thickness of the dielectric ceramic layer are being rapidly reduced. Therefore, there is an increasing demand for a dielectric ceramic material having a high dielectric constant, a small change in the dielectric constant with temperature, and excellent reliability.

However, the dielectric ceramic materials disclosed in Japanese Patent Publication No. 57-42588 and Japanese Patent Application Laid-Open No. 61-101449 can obtain a large dielectric constant, but have large crystal grains of the obtained dielectric ceramic. Become
When the thickness of the dielectric ceramic layer in the multilayer ceramic capacitor is reduced to 10 μm or less, the number of crystal grains present in one layer is reduced, and the reliability is reduced. In addition, there is also a problem that the temperature change of the dielectric constant is large, and it has not been able to meet the demands of the market.

In the dielectric ceramic material disclosed in Japanese Patent Application Laid-Open No. 62-256422, the dielectric constant is relatively high, the crystal grain of the obtained dielectric ceramic is small, and the temperature change of the dielectric constant is small. Since CaZrO ₃ and CaTiO ₃ generated in the firing process easily form a secondary phase together with MnO and the like, there was a problem in reliability at high temperatures.

In addition, the dielectric ceramic material disclosed in Japanese Patent Publication No. 61-14611 is disadvantageous in that the obtained dielectric ceramic has a dielectric constant of 2000 to 2800, and the multilayer ceramic capacitor has a small size and a large capacity. There was a disadvantage. Moreover, the X7R characteristics defined by the EIA standard, that is, a temperature range of -55 ° C to + 125 ° C
However, there is a problem that the change rate of the capacitance cannot be satisfied within ± 15%.

Further, in the non-reducing dielectric ceramic disclosed in JP-A-63-103861, BaTiO whose insulation resistance and capacitance change rate with temperature are the main components is used.
_It is greatly affected by the crystal grain size of ₃ and it is difficult to control to obtain stable characteristics. Moreover, when the insulation resistance is represented by the product of the capacitance and the capacitance (CR product), 1000 to 2000 MΩ.
-ΜF, which was not practical.

Furthermore, in the non-reducing dielectric ceramics proposed so far, various improvements have been made with respect to the deterioration of the insulation resistance in the high-temperature load life test, but the deterioration of the insulation resistance in the wet and medium load test has been improved. Was not much improved.

To solve the above problems, various compositions have been proposed in JP-A-5-9066, JP-A-5-9067 and JP-A-5-9068.
However, due to the demand for smaller and larger capacity,
In parallel with the thinning of the dielectric ceramic layers, market requirements for reliability have become more stringent, and demands for thinner dielectric ceramic materials with higher reliability have been increasing. Therefore, it has become necessary to propose a small-sized and large-capacity multilayer ceramic capacitor having excellent reliability characteristics under high temperature and high humidity.

However, if the dielectric ceramic layer is simply made thinner at a predetermined rated voltage, the electric field strength per layer increases. Therefore, the insulation resistance at room temperature and high temperature is reduced, and the reliability is significantly reduced.
Therefore, in the case of a conventional dielectric ceramic material, when the thickness of the dielectric ceramic layer is reduced, it is necessary to lower the rated voltage.

Therefore, it has become necessary to propose a multilayer ceramic capacitor which has a high insulation resistance under a high electric field strength and which is excellent in reliability, without having to lower the rated voltage even if the dielectric ceramic layer is made thinner. .

Therefore, a main object of the present invention is to provide a semiconductor device having a dielectric constant of 3,000 or more and the insulation resistance multiplied by the capacitance (CR
Room temperature at 2 kV / mm and 12
Insulation resistance at 5 ° C. is 6000 MΩ · μF, 20
Room temperature at 20 kV / mm or more
Insulation resistance at 25 ° C. is 2000 MΩ · μF, 5
00MΩ · μF or more, and the temperature characteristic of capacitance is JI
Provided is a low-cost, small-sized, large-capacity monolithic ceramic capacitor that satisfies the B characteristic defined by the S standard and the X7R characteristic defined by the EIA standard, and is excellent in weather resistance performance such as high-temperature load, wet and medium load, etc. It is in.

[0018]

That is, a first aspect of the present invention is directed to forming a plurality of dielectric ceramic layers and forming between the dielectric ceramic layers such that respective edges are exposed at both end surfaces of the dielectric ceramic layers. A multilayer ceramic capacitor including a plurality of separated internal electrodes and external electrodes provided so as to be electrically connected to the exposed internal electrodes, wherein the dielectric ceramic layer contains an alkali metal oxide contained as an impurity. Barium titanate having a content of 0.02% by weight or less, at least one or more selected from scandium oxide and yttrium oxide, at least one or more selected from samarium oxide and europium oxide, and manganese oxide , Cobalt oxide, and nickel oxide, and at least one selected from the group consisting of: α-β-γ) {BaO } m · T
iO ₂ + αM ₂ O ₃ + βRe ₂ O ₃ + γ (Mn _1-xy Ni _x C
o _y ) O (where M ₂ O ₃ is at least one kind selected from Sc ₂ O ₃ and Y ₂ O ₃ , and Re ₂ O ₃ is
At least one selected from Sm ₂ O ₃ and Eu ₂ O ₃ , and α, β, γ, m, x, y are 0.0025
≦ α + β ≦ 0.025, 0 <β ≦ 0.0075, 0.0
025 ≦ γ ≦ 0.05, γ / (α + β) ≦ 4, 0 ≦ x <
1.0, 0 ≦ y <1.0, 0 ≦ x + y <1.0, 1.0
00 <m ≦ 1.035), and 100 to 100 mol of a main component represented by the formula: The SiO ₂ —TiO ₂ —MO system (where MO is B
aO, CaO, SrO, MgO, ZnO, MnO, at least one oxide selected from the group consisting of oxide glasses of 0.2 to 3.0 parts by weight. Or it is a multilayer ceramic capacitor made of a nickel alloy.

The second invention is directed to the SiO ₂ —Ti
O ₂ -MO system (where MO is BaO, CaO, Sr
Oxide glass of at least one oxide selected from O, MgO, ZnO and MnO)
When a triangular diagram of O ₂ , TiO ₂ , and MO｝ (however, the unit is mol%), A (85, 1, 14), B (3
5, 51, 14), C (30, 20, 50), D (3
(9, 1, 60) inside or on a region surrounded by four straight lines connecting the four points, and at least one of Al ₂ O ₃ and ZrO ₂ in total with the above components as 100 parts by weight. The multilayer ceramic capacitor contains 15 parts by weight or less (however, ZrO ₂ is 5 parts by weight or less).

Further, a third invention is a multilayer ceramic capacitor in which the external electrode is constituted by a sintered layer of conductive metal powder or conductive metal powder to which glass frit is added.

Further, according to a fourth aspect of the present invention, the external electrode comprises:
A multilayer ceramic capacitor comprising a first layer formed of a sintered layer of conductive metal powder or conductive metal powder to which glass frit is added, and a second layer formed of a plating layer thereon.

[0022]

Embodiments of the present invention will be described below. In the multilayer ceramic capacitor of the present invention, as the material of the dielectric ceramic layer, barium titanate, at least one selected from scandium oxide and yttrium oxide, and at least one selected from samarium oxide and europium oxide The above and one or more selected from manganese oxide, cobalt oxide, and nickel oxide are adjusted to the above composition ratio, and magnesium oxide and a SiO ₂ —TiO ₂ —MO system (where MO is BaO, CaO, SrO, MgO, Zn
By using a dielectric ceramic material to which an oxide glass of at least one oxide selected from O and MnO) is added, even if fired in a reducing atmosphere, its characteristics are deteriorated. The temperature characteristics of the capacitance satisfy the B characteristics specified by the JIS standard and the X7R characteristics specified by the EIA standard, and at room temperature and high temperature under high electric field strength,
A multilayer ceramic capacitor having high insulation resistance and high reliability can be obtained.

Further, since the crystal grain size of the obtained dielectric ceramic layer is as small as 1 μm or less, the number of crystal grains existing in one dielectric ceramic layer can be increased, and the dielectric ceramic layer of the multilayer ceramic capacitor can be increased. The reliability can be prevented from lowering even if the thickness of the substrate is reduced.

Further, the dielectric ceramic layer is made of barium titanate, at least one selected from scandium oxide and yttrium oxide, and samarium oxide;
Among the main components of a dielectric ceramic material composed of at least one or more selected from europium oxide and at least one or more selected from manganese oxide, cobalt oxide, and nickel oxide, barium titanate in the main component thereof Among the alkaline earth metal oxides such as SrO and CaO, the alkali metal oxides such as Na ₂ O and K ₂ O, and the other oxides such as Al ₂ O ₃ and SiO ₂ , particularly Na ₂ It has been confirmed that the content of alkali metal oxides such as O and K ₂ O greatly affects the electrical characteristics.
That is, it has been confirmed that a dielectric constant of 3000 or more can be obtained by using barium titanate having an alkali metal oxide content of less than 0.02% by weight as an impurity.

Further, SiO ₂ is contained in the dielectric ceramic layer.
—TiO ₂ —MO system (where MO is BaO, Ca
By adding an oxide glass mainly containing at least one oxide selected from O, SrO, MgO, ZnO and MnO), sinterability is improved and plating resistance is improved. Have also confirmed. Furthermore, the SiO ₂ —TiO ₂ —MO system (where M
O is BaO, CaO, SrO, MgO, ZnO, Mn
Higher insulation resistance can be obtained by adding Al ₂ O ₃ and ZrO ₂ to an oxide glass mainly containing at least one oxide selected from O).

By forming a dielectric ceramic layer using the above-described dielectric ceramic material, it is possible to realize a small-sized and large-capacity multilayer ceramic capacitor with small capacitance temperature change and high reliability. At the same time, it becomes possible to use nickel or a nickel alloy or those obtained by adding a small amount of ceramic powder to them as the internal electrodes.

The composition of the external electrode is not particularly limited. For example, Ag, Pd, Ag-Pd, Cu,
Sintered layers of various conductive metal powders such as Cu alloys, or
And the conductive metal _{powder, B 2 O 3 -Li 2 O} -SiO 2 -B
aO system, B ₂ O ₃ -SiO ₂ -BaO-based, B ₂ O ₃ -SiO ₂
-ZnO system, may be composed by sintered layer containing a combination of the various glass frit Li ₂ O-SiO ₂ -BaO-based or the like. If the amount is small, ceramic powder may be added together with the conductive metal powder and glass frit. More preferably, a plating layer is coated on the sintered layer, and the plating layer is made of Ni, Cu, Ni-Cu.
A plating layer made of an alloy or the like may be used alone, or a plating layer made of solder, tin, or the like may be further provided thereon.

Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to only these examples. A multilayer ceramic capacitor according to an embodiment of the present invention will be described. FIG. 1 is a schematic sectional view of a multilayer ceramic capacitor of one embodiment, FIG. 2 is a schematic plan view of a dielectric ceramic layer having internal electrodes of one embodiment, and FIG. 3 is an exploded perspective view of the ceramic laminate of one embodiment. Show. Multilayer ceramic capacitor 1 according to the present invention
As shown in FIG. 1, the external electrode 5 and nickel, nickel, and the like are provided on both end surfaces of a ceramic laminate 3 obtained by laminating a plurality of dielectric ceramic layers 2a and 2b with an internal electrode 4 interposed therebetween.
First plating layer 6 of copper, etc. Second plating of solder, tin, etc.
It is a rectangular parallelepiped chip type on which the layer 7 is formed.

Next, a method of manufacturing the multilayer ceramic capacitor 1 according to the present invention will be described in the order of manufacturing steps. First, the ceramic laminate 3 is formed. This ceramic laminate 3 is manufactured as follows. As shown in FIG. 2, barium titanate, scandium oxide, at least one selected from yttrium oxide, samarium oxide, at least one selected from europium oxide, manganese oxide, cobalt oxide, At least one or more selected from nickel oxide, magnesium oxide, and SiO ₂ —TiO ₂ —MO system (where MO is BaO, CaO, SrO, MgO,
A dielectric ceramic layer 2 (green sheet) is prepared by slurrying a material powder comprising an oxide glass containing at least one or more oxides selected from ZnO and MnO) as a main component, and An internal electrode 4 made of nickel or a nickel alloy is formed on one surface thereof. The method for forming the internal electrodes 4 may be either screen printing or the like, or may be deposition or plating.

Next, the required number of dielectric ceramic layers 2b having the internal electrodes 4 are laminated and, as shown in FIG. 3, sandwiched between the dielectric ceramic layers 2a having no internal electrodes 4 and pressed to form a laminate. . Then, the laminated dielectric ceramic layers 2a, 2b,..., 2b, 2a are fired at a predetermined temperature in a reducing atmosphere to form a ceramic laminate 3. Next, two external electrodes 5 are formed on both end surfaces of the ceramic laminate 3 so as to be connected to the internal electrodes 4.

As the material of the external electrode 5, the same material as the internal electrode 4 can be used. Further, silver, palladium, silver-palladium alloy, copper, copper alloy and the like can be used, and B ₂ O ₃ —SiO ₂ —
BaO based glass, Li ₂ O-SiO ₂ but -BaO based material obtained by adding glass frit such as glass are also used, intended use of the multilayer ceramic capacitor, the card in consideration use location, suitable materials are selected You.

The external electrode 5 is formed by applying a conductive paste composed of a metal powder as a material to the ceramic laminate 3 obtained by firing and baking the conductive paste. An external electrode 5 may be formed by applying a conductive paste to the ceramic laminate 3 and firing the ceramic laminate 3 at the same time. Thereafter, plating of nickel, copper, or the like is performed on the external electrodes 5 to form a first plating layer 6. Finally, a second plating layer 7 of solder, tin or the like is formed on the first plating layer 6, and the chip-type multilayer ceramic capacitor 1 is manufactured.

Hereinafter, the present invention will be described in more detail with reference to examples. (Example 1) First, TiC of various purity was used as a starting material.
After preparing and weighing l ₄ and Ba (NO ₃ ) ₂ , titanyl barium oxalate (BaTiO (C ₂ O ₄ ) · 4) was treated with oxalic acid.
H ₂ O) to precipitate as to obtain a precipitate. The precipitate was thermally decomposed at a temperature of 1000 ° C. or more to synthesize four types of barium titanate (BaTiO ₃ ) shown in Table 1.

[0034]

[Table 1]

Further, 0.55SiO ₂ -0.2TiO _2-
0.1BaO-0.05CaO-0.05ZnO-0.
Oxides, carbonates and hydroxides of each component were weighed so as to have a composition ratio of 05MgO (molar ratio), mixed and pulverized, and then evaporated to dryness to obtain a powder. This powder was heated and melted at 1300 ° C. in an alumina crucible, quenched, and pulverized to obtain an oxide glass powder having an average particle diameter of 1 μm or less.

Next, BaCO ₃ for adjusting the Ba / Ti molar ratio m of barium titanate, Sc ₂ O ₃ , Y ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , and 99% or more in purity. MnCO ₃ ,
NiO, Co ₂ O ₃ and MgO were prepared. These raw material powders and the above-mentioned oxide glass powder were blended so as to have a composition ratio shown in Table 2 to obtain a blend.

[0037]

[Table 2]

An organic solvent such as a polyvinyl butyral-based binder and ethanol was added to the mixture, and the mixture was wet-mixed with a ball mill to prepare a ceramic slurry. Thereafter, the ceramic slurry was formed into a sheet by a doctor blade method to obtain a rectangular green sheet having a thickness of 11 μm. Next, a conductive paste mainly composed of Ni was printed on the ceramic green sheet to form a conductive paste layer for forming internal electrodes.

A plurality of ceramic green sheets on which the conductive paste layer was formed were laminated such that the side from which the conductive paste was drawn out was alternated to obtain a laminate. The obtained laminate is heated to a temperature of 350 ° C. in an N ₂ atmosphere to burn the binder, and then the oxygen partial pressure is 10 ⁻⁹ to 10 −10.
^It was fired at a temperature shown in Table 3 for 2 hours in a reducing atmosphere composed of H ₂ —N ₂ —H ₂ O gas at ⁻¹² MPa to obtain a ceramic sintered body. The surface of the obtained ceramic sintered body was observed with a scanning electron microscope at a magnification of 1500, and the grain size was measured.

After firing, B ₂ O ₃ was applied to both end surfaces of the obtained sintered body.
-Li ₂ O-SiO ₂ -A silver paste containing a glass frit of BaO system is applied, and 600 g is applied in an N ₂ atmosphere.
It baked at the temperature of ° C, and formed the external electrode electrically connected with the internal electrode. The external dimensions of the multilayer ceramic capacitor obtained as described above are 1.6 mm in width, 3.2 mm in length, and 1.2 mm in thickness, and the thickness of the dielectric ceramic layer interposed between the internal electrodes. Was 8 μm. The total number of effective dielectric ceramic layers was 19, and the area of the counter electrode per layer was 2.1 mm ² .

Then, the electrical characteristics of these were measured. The capacitance (C) and the dielectric loss (tan δ) are
Frequency 1kHz, 1Vr using automatic bridge type measuring instrument
ms and a temperature of 25 ° C., and a dielectric constant (ε) was calculated from the capacitance. Next, in order to measure the insulation resistance (R), a DC voltage of 16 V was applied for 2 minutes using an insulation resistance meter, and the insulation resistance (R) at 25 ° C. and 125 ° C. was measured. The product of (C) and the insulation resistance (R), that is, the CR product was determined. In order to measure the insulation resistance (R) in an electric field of 20 kV / mm, a DC voltage of 160 V
In the same manner, the insulation resistance (R) at 25 ° C. and 125 ° C. was measured to determine the CR product.

Further, the rate of change of the capacitance with respect to the temperature change was measured. The rate of change of the capacitance with respect to the temperature change was −25 based on the capacitance at 20 ° C.
C and 85 ° C. (ΔC / C 20 ° C.), -55 ° C. and 125 ° C. based on the capacitance at 25 ° C. (ΔC / C 25 ° C.), and −55 ° C. to 125 ° C. The value (| ΔC / △) whose change rate is the maximum as an absolute value within the range of
C25 ° C. | max).

As a high-temperature load life test, 36 samples were applied at a temperature of 150 ° C. and a DC voltage of 100 V was applied, and the change with time of the insulation resistance was measured. In the high-temperature load life test, the insulation resistance value (R) of each sample was 10 ⁶ Ω.
The time when the following condition is reached is defined as the lifetime, and the average lifetime is shown.

Further, as a wet load test, each sample was subjected to 7 tests.
2 at a time, 2 atm (100% relative humidity), temperature 121 ° C
Indicates the number of samples having an insulation resistance value (R) of 10 ⁶ Ω or less by the time 250 hours have passed when a DC current of 16 V was applied. Table 3 shows the above results.

[0045]

[Table 3]

As is clear from Tables 1, 2 and 3, the multilayer ceramic capacitor of the present invention has a high dielectric constant of 3000 or more, a dielectric loss of 2.5% or less, and a rate of change of capacitance with temperature. JIS in the range of -25 ℃ ~ 85 ℃
B characteristic standard specified in the standard and -55 ° C and 1
X7R specified in EIA standard within the range at 25 ° C
Satisfies the characteristic standards. In addition, when the insulation resistance at 25 ° C. and 125 ° C. at a high electric field strength of 20 kV / mm is represented by CR products, 2000 MΩ · μF and 500 MΩ, respectively.
・ High value of μF or more. In addition, the average life time is 50
The time is as long as 0 hours or more, and no failure is observed in the humidity and load test. Furthermore, sintering can be performed at a relatively low temperature of 1300 ° C. or less, and the particle size is as small as 1 μm or less.

Here, the reason for limiting the composition of the dielectric ceramic material used for the multilayer ceramic capacitor of the present invention will be described. (1-α-β-γ) {BaO} _m · TiO ₂ + αM ₂ O ₃ +
βRe ₂ O ₃ + γ (Mn _1-xy Ni _x Co _y ) O (however,
M ₂ O ₃ is Sc ₂ O _3, at least one kind selected from among _{Y 2 O 3, Re 2 O} 3 is at least one or more selected from among _{Sm 2 O 3, Eu 2 O} 3) , The (M ₂ O ₃ + Re ₂ O ₃ ) amount (α + β) is 0.
If less than 0025, the dielectric constant is lower than 3000,
This is because the temperature change rate of the capacitance also increases, the insulation resistance at a high voltage at 125 ° C. decreases, and the average life time becomes extremely short. As shown in sample No. 19, (M ₂ O ₃ + Re
_{When the} amount of (2O ₃ ) (α + β) exceeds 0.025, the dielectric constant is lower than 3000, the insulation resistance at 25 ° C. and 125 ° C. decreases, the average life time is short, and the load test is poor in a wet load test. Is generated and the sintering temperature increases.

As shown in sample No. 2, (Mn, Ni, Co)
If the O content γ is less than 0.0025, firing in a reducing atmosphere reduces the dielectric ceramic, turns it into a semiconductor, and lowers the insulation resistance. When the (Mn, Ni, Co) O amount γ exceeds 0.05 as in Sample No. 20, the insulation resistance at 125 ° C. becomes low and the average life time becomes short without depending on the applied voltage. Also, the rate of temperature change of the capacitance increases.

As shown in sample numbers 23, 24 and 25, Mn
Is not included at all, the insulation resistance decreases and the average life time becomes shorter than 500 hours.

This is because when the amount β of Re ₂ O ₃ is 0 as in sample No. 3, the average life time is shorter than 500 hours. As in Sample No. 22, the Re ₂ O ₃ amount β is 0.
When the value exceeds 0075, the temperature change rate of the capacitance becomes large, and the JIS standard B characteristic and the EIA standard X7
This is because the R characteristic is no longer satisfied.

As shown in sample No. 21, (M ₂ O ₃ + Re ₂
When the ratio γ / (α + β) of the O ₃ ) amount (α + β) and the (Mn, Ni, Co) O amount γ exceeds 4, the temperature change rate of the capacitance becomes large and the insulation resistance at 125 ° C. Is low,
This is because the average life is shorter than 500 hours.

When the molar ratio m of barium titanate is 1.000 or less as in Sample Nos. 4 and 5, when baked in a reducing atmosphere, the barium titanate turns into a semiconductor or has low insulation resistance and has an average life time of Is shorter than 500 hours. As shown in Sample No. 26, the molar ratio m was 1.035.
This is because if the ratio exceeds sinterability, the sinterability becomes extremely poor.

When the amount of MgO is less than 0.5 mol as in sample No. 6, the insulation resistance is reduced, the average life time is shorter than 500 hours, and the temperature change rate of the capacitance is J.
This is because, while satisfying the B characteristic defined by the IS standard, the X7R characteristic defined by the EIA standard cannot be satisfied. When the amount of MgO exceeds 5.0 mol as in Sample No. 27, the sintering temperature becomes high and the dielectric constant becomes 300
This is because it is lower than 0, the average life time is short, and a failure occurs in a wet and medium load test.

As shown in Sample No. 7, SiO ₂ —TiO ₂ —
If the amount of the MO-based oxide glass is less than 0.2 parts by weight, sintering will be insufficient. As in Sample No. 28, if the amount of oxide glass of SiO ₂ -TiO ₂ -MO-based exceeds 3.0 parts by weight, because the dielectric constant does not exceed 3000.

As shown in Sample No. 29, the amount of alkali metal oxide contained as an impurity in barium titanate was 0.1%.
If the amount exceeds 02 parts by weight, the dielectric constant will decrease.

The ratio (β / α) of the amount of Re ₂ O _{3 to the} amount of M ₂ O ₃ α (β / α) is not particularly specified, but in order to allow the temperature change rate of the capacitance to have a margin from the allowable value of the standard, β / α
It is preferred that ≦ 1.

Example 2 As a dielectric ceramic material, barium titanate shown in A of Table 1 was used, and 98.0 was used.
{BaO} _1.010 TiO ₂ + 0.8Y ₂ O ₃ + 0.1Sm ₂
O ₃ + 0.1Eu ₂ O ₃ +1.0 (Mn _0.7 Ni _0.1 C
o _0.3 ) (molar ratio), a raw material mixed with 0.8 mol of MgO was prepared, and heated at 1200 ° C. to 1500 ° C. in the same manner as in Example 1 to produce Table 4. Was added, and an external electrode made of silver electrically connected to the internal electrode was formed in the same manner as in Example 1 by adding a SiO ₂ —TiO ₂ —MO-based oxide glass having an average particle diameter of 1 μm or less. A multilayer ceramic capacitor was manufactured. The outer dimensions of the manufactured multilayer ceramic capacitor are the same as those of the first embodiment.

[0058]

[Table 4]

Then, the electrical characteristics of these were measured. The capacitance (C) and the dielectric loss (tan δ) are
Frequency 1kHz, 1Vr using automatic bridge type measuring instrument
ms and a temperature of 25 ° C., and a dielectric constant (ε) was calculated from the capacitance. Next, in order to measure the insulation resistance (R), a DC voltage of 16 V was applied for 2 minutes using an insulation resistance meter, and the insulation resistance (R) at 25 ° C. and 125 ° C. was measured. I asked. Further, in order to measure the insulation resistance (R) in an electric field of 20 kV / mm, a DC voltage of 160 V was applied for 2 minutes, the insulation resistance (R) was measured at 25 ° C. and 125 ° C., and the CR product was calculated. I asked.

Further, the rate of change of the capacitance with respect to the temperature change was measured. The rate of change of the capacitance with respect to the temperature change was −25 ° C. based on the capacitance at 20 ° C.
And the rate of change at 85 ° C. (ΔC / C 20 ° C.), the rate of change at −55 ° C. and 125 ° C. based on the capacitance at 25 ° C. (ΔC / C 25 ° C.) and the rate of change from −55 ° C. to 125 ° C. A value (| ΔC / C) at which the rate of change is maximum as an absolute value within the range
25 ° C. | max).

As a high-temperature load life test, 36 samples were applied at a temperature of 150 ° C. and a DC voltage of 100 V was applied, and the change in insulation resistance with time was measured. In the high-temperature load life test, the insulation resistance value (R) of each sample was 10 ⁶ Ω.
The time when the following condition is reached is defined as the lifetime, and the average lifetime is shown.

Further, each sample was subjected to a humidity and medium load test as follows.
2 at a time, 2 atm (100% relative humidity), temperature 121 ° C
Indicates the number of samples having an insulation resistance value (R) of 10 ⁶ Ω or less by the time 250 hours have passed when a DC current of 16 V was applied. Table 5 shows the above results.

[0063]

[Table 5]

As is clear from Tables 4 and 5, the multilayer ceramic capacitor composed of a dielectric ceramic layer containing an SiO ₂ —TiO ₂ —MO-based oxide glass according to the present invention has a dielectric constant of 3000 or more. And the dielectric loss is 2.5% or less, and the rate of change of the capacitance with respect to temperature is-
The B characteristic standard specified in the JIS standard in the range of 25 ° C to 85 ° C and the E characteristic in the range of -55 ° C and 125 ° C
Satisfies the X7R characteristic standard specified in the IA standard.
Moreover, at 25 ° C. and 12 kV at a high electric field strength of 20 kV / mm.
The insulation resistance at 5 ° C. shows high values of 2000 MΩ · μF and 500 MΩ · μF or more, respectively, when expressed by CR products.

Further, the average life time is as long as 500 hours or more, and no failure occurs in the wet and medium load test. further,
Sintering can be performed at a relatively low temperature of 1300 ° C. or less, and the particle size is as small as 1 μm or less.

Here, the reasons for limiting the composition of the oxide glass used in the multilayer ceramic capacitor of the present invention will be described. SiO ₂ —TiO ₂ —MO system (where MO is B
The oxide glass of at least one oxide selected from aO, CaO, SrO, MgO, ZnO, and MnO) has a triangular diagram of {SiO ₂ , TiO ₂ , MO} shown in FIG. , SiO ₂ is 85 mol%, TiO ₂ is 1 mol%, the point a indicates a composition MO is 14 mol%, SiO ₂
B having a composition of 35 mol%, 51 mol% of TiO _{2 and} 14 mol% of MO, 30 mol% of SiO ₂ and TiO ₂
C is 20 mol% and MO is 50 mol%.
SiO ₂ 39 mol%, TiO ₂ 1 mol%, MO 60
Sample No. 4 which is inside or outside the range surrounded by four straight lines connecting the four points with point D indicating the composition of mol%
This is because sintering is insufficient for 2 to 48, or even if sintering, a failure occurs in the wet and medium load test.

As shown in Sample Nos. 40 and 41, SiO ₂ -T
the oxide glass consisting iO ₂ -MO-based, Al ₂ O _3, Z
By including rO ₂ , 16 V is applied (electric field intensity 2 k
Insulation resistance at 25 ° C. and 125 ° C. is 7000 MΩ · μF and 3000 MΩ · μF or more, respectively.
Insulation resistance with V applied (electric field strength 20 kV / mm) is 25
3000 MΩ · μF and 1000 at 125 ° C and 125 ° C, respectively.
Although a multilayer capacitor of MΩ · μF or more is obtained, when the addition amount of Al ₂ O ₃ exceeds 15 parts by weight and the addition amount of ZrO ₂ exceeds 5 parts by weight as in sample numbers 46 and 47, sintering is performed. This is because the sex is extremely reduced.

In the above embodiment, powder produced by the oxalic acid method was used as barium titanate. However, the present invention is not limited to this. Barium titanate powder produced by the alkoxide method or hydrothermal synthesis is used. May be used. The use of these powders may improve the characteristics shown in this example. In addition, scandium oxide, yttrium oxide, samarium oxide, europium oxide, manganese oxide, cobalt oxide, nickel oxide, magnesium oxide, and the like also used oxide powder, but are not limited thereto, and are not limited thereto. If blended to constitute the dielectric ceramic layer,
The use of a solution of an alkoxide, an organic metal or the like does not impair the properties obtained at all.

[0069]

The multilayer ceramic capacitor of the present invention is made of a dielectric ceramic material which is not reduced even when fired in a reducing atmosphere and does not turn into a semiconductor.
Nickel or a nickel alloy, which is a base metal, can be used as the electrode material, and can be sintered at a relatively low temperature of 1300 ° C. or less, and the cost of the multilayer ceramic capacitor can be reduced.

The multilayer ceramic capacitor using this dielectric ceramic material has a dielectric constant of 3000 or more and a small temperature change in the dielectric constant. In addition, it has high insulation resistance and shows excellent characteristics without deterioration in characteristics under high temperature and high humidity. Therefore, it is not necessary to lower the rated voltage even if the dielectric ceramic layer is thinned.

Further, since the crystal grain size is as small as 1 μm or less, the amount of crystal grains present in the dielectric ceramic layer can be increased when the dielectric ceramic layer is made thinner as compared with a conventional multilayer ceramic capacitor. Therefore, a highly reliable, small-sized, large-capacity multilayer ceramic capacitor can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention.

FIG. 2 is a schematic plan view of a dielectric ceramic layer having internal electrodes according to one embodiment of the present invention.

FIG. 3 is an exploded perspective view of a ceramic laminate according to one embodiment of the present invention.

FIG. 4 is a three-component composition diagram of {SiO ₂ , TiO ₂ , MO} showing the composition range of an SiO ₂ —TiO ₂ —MO-based oxide glass.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multilayer ceramic capacitor 2 Dielectric ceramic layer 2a Dielectric ceramic layer without internal electrode 2b Dielectric ceramic layer with internal electrode 3 Ceramic laminate 4 Internal electrode 5 External electrode 6 Plating first layer 7 Plating second layer

Claims (4)

[Claims] A plurality of dielectric ceramic layers; a plurality of internal electrodes formed between the dielectric ceramic layers such that respective edges thereof are exposed at both end surfaces of the dielectric ceramic layers; In a multilayer ceramic capacitor including an external electrode provided so as to be electrically connected to an electrode, the dielectric ceramic layer may be a titanium ceramic having an alkali metal oxide content of 0.02% by weight or less as an impurity. Barium acid, at least one selected from scandium oxide, yttrium oxide, at least one selected from samarium oxide, europium oxide, and at least selected from manganese oxide, cobalt oxide, nickel oxide consists of a one or more the following composition formula, (1-α-β- γ) {BaO} m · TiO 2 αM ₂ O ₃ +
βRe ₂ O ₃ + γ (Mn _1-xy Ni _x Co _y ) O (where M ₂ O ₃ is at least one kind selected from Sc ₂ O ₃ and Y ₂ O ₃ , and Re ₂ O ₃ Is Sm
_At least one selected from ₂ O ₃ and Eu ₂ O ₃ , and α, β, γ, m, x, and y are 0.0025 ≦ α + β ≦ 0.0250 <β ≦ 0.00750. .0025 ≦ γ ≦ 0.05 γ / (α + β) ≦ 40 ≦ x <1.00 <y <1.00 <x + y <1.0 1.000 <m ≦ 1.035) With respect to 100 moles of the main component, 0.5 to 5.0 moles of magnesium oxide was added and contained as a subcomponent in terms of MgO. Further, the total of the main component and the magnesium oxide was 100 parts by weight, and SiO _{2 was used.} —TiO ₂ —MO system (where MO is BaO, CaO, SrO, MgO, Zn
O, MnO, at least one oxide selected from the group consisting of oxide glass of 0.2 to 3.0 parts by weight, and the internal electrode is made of nickel or a nickel alloy. A multilayer ceramic capacitor characterized by the following. 2. The SiO ₂ —TiO ₂ —MO system (where MO is BaO, CaO, SrO, MgO, Zn)
Oxide glass of at least one oxide selected from O and MnO) is {SiO ₂ , TiO ₂ , MO}
A (85, 1, 14) B (35, 51, 14) C (30, 20, 50) D (39, 1, 60) Al ₂ O ₃ and ZrO are located inside or on the line surrounded by the four straight lines connecting the points, with the above components as 100 parts by weight.
_2. The multilayer ceramic capacitor according to claim 1, wherein at least one of ₂ is added and contained in a total of 15 parts by weight or less (ZrO ₂ is 5 parts by weight or less). 3. The external electrode according to claim 1, wherein the external electrode is formed of a sintered layer of a conductive metal powder or a conductive metal powder to which glass frit is added. The multilayer ceramic capacitor as described in the above. 4. The external electrode comprises a first layer formed of a sintered layer of conductive metal powder or conductive metal powder to which glass frit is added, and a second layer formed of a plating layer thereon. The multilayer ceramic capacitor according to claim 1, wherein: