JPH1095667A - Dielectric ceramic composition and ceramic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dielectric ceramic composition freed from a problem of the rise in electric field intensity between the electrodes, resulting in serious deterioration of the direct current characteristics and reliability when a dielectric ceramic base is thinned in order to increase the capacitance of a ceramic capacitor. SOLUTION: This dielectric ceramic composition is obtained by baking a mixture of the basic component expressed by the composition formula (BaαCaβErγOk ) (Ti1-x Zrx O2 ) (0.01<=β<=0.12, 0.003<=γ<=0.026, 0.996<=α+β+γ<=1.020, 0.10<=(x)<=0.21, and the value of (k) settles necessarily by the settlement of the values of α, β and γ) and an ingredient consisting of Mg compound, Mn compound and Si compound. Based on 100 pts.wt. of the basic component, 0.04 to 0.12 pt.wt. of the Mg compound in terms of MgO, 0.05 to 0.50 pt.wt. of the Mn compound in terms of MnO and 0.05 to 0.50 pt.wt. of the Si compound in terms of SiO2 are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-permittivity dielectric ceramic composition containing barium titanate as a basic component and a single-layer or multilayer-structured ceramic capacitor using the same.

[0002]

2. Description of the Related Art As a material for a dielectric ceramic substrate of a ceramic capacitor, a dielectric ceramic composition containing BaTiO ₃ as a main component, or a part of Ba of BaTiO ₃ is replaced by Ca, and a part of Ti is replaced by Zr. It is known to use a dielectric porcelain composition substituted with:

For example, JP-A-6-52718, JP-A-6-103812, and JP-A-6-203632
Gazette, JP-A-6-203633, JP-A-6-2
JP-A-036343, JP-A-6-203635 and JP-A-6-203632 disclose a dielectric ceramic composition of this type and a ceramic capacitor using the same.

According to these publications, the thickness of a single-layer dielectric ceramic substrate (dielectric ceramic body) has been reduced to about 5 μm with the miniaturization and large capacity of the laminated ceramic capacitor. The relative permittivity ε _{s is} also set to exceed 20,000.

[0005]

By the way, progress in miniaturization of electronic equipment in recent years has not stopped.
The density of electronic circuits has also been remarkably increased, and there has been a further demand for porcelain capacitors, which are components thereof, to increase their capacitance and improve their reliability.

In order to increase the capacitance of the ceramic capacitor, it is conceivable to reduce the thickness of the dielectric ceramic substrate interposed between the pair of electrodes. However, when the thickness of the dielectric ceramic substrate is reduced, the electric field strength between the pair of electrodes increases. When the specific dielectric constant epsilon _s is too high, resulting in remarkably deteriorated DC bias characteristic by an increase in the electric field strength. In addition, when particles having a large particle size exist in the dielectric ceramic substrate, the DC bias characteristics are further deteriorated, which may lead to a reduction in reliability.

The present invention densifies by firing at a temperature of about 1250 ° C. and has a maximum relative dielectric constant ε _s of 12000 to 1400.
0. An object of the present invention is to provide a dielectric ceramic composition having an average crystal grain size of 3 μm or less and no particles having a size of 5 μm or more, and a ceramic capacitor having a single-layer or multilayer structure using the same.

[0008]

The dielectric porcelain composition according to the present invention has a composition formula (BaαCaβErγO _k ) (Ti
_1-x Zr _x O ₂ ) (provided that 0.01 ≦ β ≦ 0.12
0.003 ≦ γ ≦ 0.026, 0.996 ≦ α + β +
γ ≦ 1.020, 0.10 ≦ x ≦ 0.21) and a mixture obtained by calcining a mixture of an additive component composed of a Mg compound, a Mn compound and a Si compound. Parts by weight, the Mg compound was 0.04 to 0.12 parts by weight in terms of MgO,
The n compound is 0.05 to 0.50 parts by weight in terms of MnO, and the Si compound is 0.05 to 0.5 parts by weight in terms of SiO _2.
0.50 parts by weight.

Further, the ceramic capacitor according to the present invention is obtained by laminating one or more dielectric ceramic substrates made of a dielectric ceramic composition and two or more electrodes sandwiching the dielectric ceramic substrate. Wherein the dielectric ceramic composition has a composition formula (BaαCaβErγO _k ) (Ti
_1-x Zr _x O ₂ ) (provided that 0.01 ≦ β ≦ 0.12
0.003 ≦ γ ≦ 0.026, 0.996 ≦ α + β +
γ ≦ 1.020, 0.10 ≦ x ≦ 0.21) and a mixture obtained by calcining a mixture of an additive component composed of a Mg compound, a Mn compound and a Si compound. Parts by weight, the Mg compound was 0.04 to 0.12 parts by weight in terms of MgO,
The n compound is 0.05 to 0.50 parts by weight in terms of MnO, and the Si compound is 0.05 to 0.5 parts by weight in terms of SiO _2.
0.50 parts by weight.

In the above composition formula of the basic components of the dielectric ceramic composition, the value of β indicating the molar ratio of Ca is 0.01 ≦ β
The reason for ≦ 0.12 is that when β is less than 0.01, particles of 5 μm or more are formed in the dielectric ceramic composition, the DC bias characteristic of the dielectric ceramic composition exceeds −70%, and β is If it exceeds 0.12, the maximum relative dielectric constant ε of the dielectric ceramic composition
_{This is because max} becomes less than 12,000.

Further, the value of γ indicating the molar ratio of Er is set to 0.
The reason why 003 ≦ γ ≦ 0.026 is that when γ is less than 0.003, the average particle diameter of the particles in the dielectric ceramic composition is 3 μm.
m, particles of 5 μm or more are formed in the dielectric ceramic composition, the DC bias characteristic exceeds -70%, and γ is 0.1%.
026, the maximum relative permittivity ε of the dielectric ceramic composition
_{This is because max} becomes less than 12,000.

Further, the molar ratio of Ba + Ca + Er (A / B
Ratio), the value of α + β + γ is 0.996 ≦ α + β + γ
The reason for setting ≦ 1.020 is that if α + β + γ is less than 0.996, particles of 5 μm or more are formed in the dielectric ceramic composition, and if α + β + γ exceeds 1.020, a dense sintered body cannot be obtained. It is.

Further, the value of x indicating the molar ratio of Zr is set to 0.
The reason why 10 ≦ x ≦ 0.21 is that when x is less than 0.10, the maximum relative permittivity ε _{max of the} dielectric ceramic composition is 1200
If it is less than 0, tan δ exceeds 1.2%, DC bias characteristics exceed -70%, and x exceeds 0.21, the maximum relative permittivity ε _{max of the} dielectric ceramic composition becomes less than 12,000. It is.

The value of α indicating the molar ratio of Ba is 0.1.
The value satisfies the expression of 996 ≦ α + β + γ ≦ 1.020, which is obtained by calculation from the composition formula of the basic component. The value of k is a numerical value that is inevitably determined by determining the values of α, β, and γ.

Further, with respect to 100 parts by weight of the basic component,
The Mg compound is converted to MgO by 0.04 to 0.12.
The parts by weight are as follows.
When the amount is less than 04 parts by weight, the DC bias characteristics of the dielectric ceramic composition exceed -70%, and when the average particle diameter of the particles forming the dielectric ceramic composition exceeds 3 μm and exceeds 0.12 parts by weight. The maximum relative dielectric constant ε _{max of the} dielectric ceramic composition is 12
This is because it is less than 000.

Further, with respect to 100 parts by weight of the basic component,
The Mn compound is converted to MnO at 0.05 to 0.50.
The parts by weight are such that the amount of the Mn compound is 0.1 in terms of MnO.
When the amount is less than 05 parts by weight, the resistivity ρ at 150 ° C. of the dielectric ceramic composition is less than 5 × 10 ^5, and when it exceeds 0.50 parts by weight, a dense sintered body cannot be obtained.

Further, based on 100 parts by weight of the basic component,
The Si compound is converted to SiO ₂ by 0.05 to 0.5.
When the Si compound is less than 0.05 parts by weight in terms of SiO ₂ , a dense sintered body cannot be obtained. When the Si compound exceeds 0.50 parts by weight, the dense sintered body cannot be obtained. This is because it cannot be obtained.

The Mg compound includes MgO,
MgCO ₃ , Mg (OH) ₂ , etc.
Anything that produces O can be used. The Mn compounds include MnO, Mn ₃ O ₄ , Mn ₂ O
₃ , MnO ₂ , Mn (OH) ₂ , MnO (OH), Mn
CO ₃ or any other material that produces MnO by firing can be used. Further, as the Si compound,
SiO ₂ , SiO ₂ .nH ₂ O, silicone, and other materials that generate SiO ₂ by firing can be used.

Further, Pd, A
What is formed by firing a conductive paste mainly containing noble metal fine particles such as g-Pd, Pt, and Au can be used.

In the embodiments described later, a ceramic capacitor having a single-layer structure is mainly described. However, there is no essential difference between a ceramic capacitor having a single-layer structure and a ceramic capacitor having a multilayer structure. The present invention can be applied to not only a laminated ceramic capacitor but also a laminated ceramic capacitor.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, sample Nos. The case of 1 will be described.

First, as a raw material of the basic component, a predetermined amount of B
aCO ₃ , CaCO ₃ , Er ₂ O ₃ , TiO ₂ and Zr
O ₂ was each weighed.

Here, each weighed value of these compounds is determined by the composition formula (BaαCaβErγO _k ) (Ti
_1-x Zr _x O ₂ ), the molar ratios α, β, γ, and x of the respective elements are shown in Table 1. In the case of the composition formula (Ba)
_{0.939 Ca 0.050 Er 0.015 O k)} (Ti 0.084 Zr
_0.016 O ₂ )... It is a value calculated and calculated so as to satisfy (1).

Next, these compounds are put into a ball mill, water is added, and the mixture is sufficiently pulverized and mixed by a wet method. The obtained slurry is put into a drier and dried, and is dried at 1150 ° C. in an air atmosphere (oxidizing atmosphere). For 2 hours to obtain a powder of a basic component having a composition represented by the composition formula (1).

Next, 0.10 parts by weight of MgO, 0.21 parts by weight of MnO, and 0.10 parts by weight of SiO ₂ were weighed with respect to 100 parts by weight of the basic components. Put the ingredients in a ball mill, add water,
The slurry was sufficiently pulverized and mixed by a wet method, and the obtained slurry was placed in a drier and dried to obtain a powder of a porcelain material.

Next, an organic binder was added to the powder of the porcelain material, kneaded sufficiently, and the mixture was molded by a dry press to obtain a disk-shaped compact having a diameter of 10 mm and a thickness of 0.5 mm. Then, the molded body is fired and sintered at 1250 ° C. for 2 hours in an air atmosphere (oxidizing atmosphere).
A dielectric ceramic substrate was obtained.

Next, Ag is applied to the front and back surfaces of the dielectric ceramic substrate.
The paste was applied and baked at 800 ° C. to form electrodes, thereby obtaining a porcelain capacitor as shown in FIG. In FIG. 1, reference numeral 10 denotes a ceramic capacitor. The ceramic capacitor 10 includes a disk-shaped dielectric ceramic substrate 12 and a pair of electrodes 14, 14 sandwiching the dielectric ceramic substrate 12.

[0028]

[Table 1]

Next, regarding the ceramic capacitor obtained as described above, the maximum relative permittivity ε of the dielectric ceramic substrate
_max , tan δ, specific resistance ρ, DC bias characteristics ΔC, and average particle diameter D were measured in the following manner.

(A) Maximum relative permittivity ε _{max A} ceramic capacitor is placed in a thermostat, and the maximum capacitance when the temperature is changed from −25 to + 85 ° C. is measured using an impedance analyzer under the conditions of 1 kHz and 1 V _rms . The maximum relative dielectric constant ε _max was calculated from the measured values, the thickness of the dielectric ceramic base, and the electrode area.

(B) Tan δ Tan δ was measured at 20 ° C. using an impedance analyzer.

(C) Resistivity ρ Under a condition of 150 ° C., a voltage of 100 V DC is applied to the porcelain capacitor for 20 seconds to measure the insulation resistance, and the resistance is determined from the insulation resistance, the thickness of the dielectric porcelain base, and the electrode area. The rate ρ was calculated.

(D) DC bias characteristic ΔC 0.5 calculated from the capacitance C _{0 at} 20 ° C. and the thickness.
The capacitance C _Bias at 20 ° C. when a DC voltage corresponding to V / μm was applied was measured, and the DC bias characteristic ΔC was calculated using the following equation. ΔC = (C _Bias −C ₀ ) / C ₀ × 100 (%)

(E) Average particle diameter D The surface of the dielectric porcelain base before the electrodes are formed is randomly
Select the spots and use a scanning microscope at 2000x or 5
Photographed at a magnification of 000 times,
Zero crystal grains were randomly selected, the size was measured by the intercept method, and the average value was determined.

Sample No. In the case of 1, as shown in Table 2,
The maximum relative permittivity ε _max is 13300 and tan δ is 0.71
%, Resistivity ρ is 4.47 × 10 ⁶ MΩ · cm (expressed as 4.47E + 06 MΩ · cm in Table 2), DC bias characteristic ΔC is −53%, and average particle diameter D is 2.8 μm.
m, and no particles larger than 5 μm were present.

[0036]

[Table 2]

Next, the sample Nos. Samples having the component compositions shown in Sample Nos. A porcelain capacitor was prepared in the same manner as in the case of No. 1 and various characteristics thereof were examined.

As is clear from Tables 1 and 2, Sample No. 3 satisfying the composition specified in the present invention. 1,3,4,7,
8, 11, 12, 15, 16, 19, 20, 23, 2
The ceramic capacitors of 4, 27, 28 and 30 to 35 have a maximum relative dielectric constant ε _max of 12000 or more, a tan δ at 20 ° C. of 1.2% or less, and a resistivity ρ at 150 ° C. of 5 × 10 ^5.
The change in electrostatic capacity (dielectric constant) when a bias voltage of 0.5 V / μm or more was applied was smaller than −70%, the average particle size was 3 μm or less, and no particles were 5 μm or more. . On the other hand, the sample No. 2,5,6,9,1
0,13,14,17,18,21,22,25,2
Samples Nos. 6 and 29 did not satisfy the target characteristics, and are comparative examples of the present invention.

Next, from the results shown in Table 2, the optimum range of the component composition of the dielectric ceramic composition will be verified. First, when the value of β is the sample In the case of 0.01 as shown in FIG. As shown in FIG. 2, in the case of 0, particles of 5 μm or more are formed, and the DC bias characteristic ΔC exceeds -70%. Therefore, the lower limit of β is 0.01.

Further, when the value of β is the sample No. In the case of 0.12 as shown in FIG. 5
Maximum relative permittivity epsilon _max in the case of 0.14 as shown in the 1
Less than 2000. Therefore, the upper limit of β is 0.12.

Next, when the value of γ is the sample No. In the case of 0.003 as shown in FIG.
As shown in FIG. 6, in the case of 0.01, the average particle diameter D exceeds 3 μm, particles of 5 μm or more are formed, and the DC bias characteristic ΔC exceeds −70%. Therefore, the lower limit of γ is 0.0
03.

Further, when the value of γ is the sample No. In the case of 0.026 as shown in FIG.
As shown in FIG. 9, in the case of 0.028, the maximum relative permittivity ε _max
Is less than 12,000. Therefore, the upper limit of γ is 0.0
26.

Next, the value of α + β + γ is the same as that of sample No. 11
In the case of 0.996 as shown in FIG.
Sample No. 5 μm for 0.994 as shown in FIG.
The above particles are formed. Therefore, the lower limit of α + β + γ is 0.996.

Further, when the value of α + β + γ is the value of Sample No. 12
In the case of 1.020 as shown in FIG.
Sample No. As shown in FIG. 13, in the case of 1.029, a dense sintered body cannot be obtained. Therefore, the upper limit of α + β + γ is 1.020.

Next, when the value of x is the sample No. In the case of 0.10 as shown in FIG.
As shown in FIG. 14, in the case of 0.08, the maximum relative permittivity ε _max
Is less than 12000, tan δ exceeds 1.2%,
In addition, the DC bias characteristic ΔC exceeds -70%. Therefore, the lower limit of x is 0.10.

When the value of x is the sample No. In the case of 0.21, as shown in FIG.
As shown in FIG. 17, in the case of 0.22, ε _max is 12000.
Less than. Therefore, the upper limit of x is 0.21.

Next, Mg was added to 100 parts by weight of the basic component.
When the amount of O added to Sample No. In the case of 0.04 parts by weight as shown in FIG. In the case of 0.02 parts by weight as shown in FIG.
Exceeds -70%, and the average particle size also exceeds 3 µm. Therefore, the lower limit of the amount of MgO added is 0.04.

Further, Mg relative to 100 parts by weight of the basic component
When the amount of O added to Sample No. In the case of 0.12 parts by weight as shown in FIG. As shown in FIG. 21, in the case of 0.13 parts by weight, the maximum relative dielectric constant ε _max is less than 12,000. Therefore, the upper limit of the added amount of MgO is 0.12 parts by weight.

Next, Mn based on 100 parts by weight of the basic component
When the amount of O added to Sample No. In the case of 0.05 part by weight as shown in FIG. As shown in FIG. 22, in the case of 0.02 parts by weight, the resistivity ρ at 150 ° C. is less than 5 × 10 ⁵ MΩ · cm. Therefore, the lower limit of MnO is 0.05 parts by weight.

Further, Mn based on 100 parts by weight of the basic component
When the amount of O added to Sample No. In the case of 0.50 parts by weight as shown in FIG. As shown in Fig. 25, when the content is 0.60 parts by weight, a dense sintered body cannot be obtained. Therefore, the upper limit of the amount of MnO added is 0.50 parts by weight.

Next, Si was added to 100 parts by weight of the basic component.
When the addition amount of O ₂ is 0.05 as shown in 27
In the case of parts by weight, desired characteristics are obtained. In the case of 0.02 parts by weight as shown in 26, a dense sintered body cannot be obtained. Therefore, the lower limit of the added amount of SiO ₂ is 0.05
Parts by weight.

In addition, Si based on 100 parts by weight of the basic component
When the addition amount of O ₂ is 0.50 as shown in 28
In the case of parts by weight, desired characteristics are obtained. In the case of 0.60 parts by weight as shown in 29, a dense sintered body cannot be obtained. Therefore, the upper limit of the added amount of SiO ₂ is 0.5
0 parts by weight.

In the above embodiment, BaCO ₃ , CaCO ₃ , Er ₂ O ₃ , TiO ₂ and ZrO ₂ were used as the raw materials of the basic components. However, other oxides, carbonates, hydroxides, etc. BaO, CaO, E by firing
Compounds that produce r ₂ O ₃ , TiO ₂ , and ZrO ₂ may be used.

In the above embodiment, the raw material mixture of the basic components is calcined at 1150 ° C.
It can be changed in the range of 00 to 1300 ° C. Also,
Si, Mn, and Mg may be added from the beginning to perform calcination.

In the above embodiment, a single-layer ceramic capacitor has been described. However, similar results were obtained with a multilayer ceramic capacitor.

[0056]

According to the present invention, since the dielectric ceramic composition constituting the dielectric ceramic substrate of the ceramic capacitor has the above-described composition, the dielectric ceramic substrate can be made thinner. There is an effect that the DC bias characteristics are improved and the size and capacity of the ceramic capacitor can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a ceramic capacitor.

[Explanation of symbols]

 Reference Signs List 10 porcelain capacitor 12 dielectric porcelain base 14 electrode

Claims (2)

[Claims] 1. The composition formula (BaαCaβErγO _k ) (T
i _1-x Zr _x O ₂ ) (provided that 0.01 ≦ β ≦ 0.12
0.003 ≦ γ ≦ 0.026, 0.996 ≦ α + β
+ Γ ≦ 1.020, 0.10 ≦ x ≦ 0.21) and a mixture obtained by calcining a mixture of an additive component composed of a Mg compound, a Mn compound and a Si compound. Parts, the Mg compound is M
0.04-0.12 parts by weight in terms of gO, the Mn 0.05 to 0.50 part by weight compound in terms of MnO, the Si compound in terms of SiO ₂ .05 to 0. 50
A dielectric porcelain composition characterized by being contained in parts by weight. 2. A ceramic capacitor comprising one or two or more dielectric ceramic bases made of a dielectric ceramic composition and two or more electrodes sandwiching the dielectric ceramic base, wherein the dielectric capacitor comprises: The porcelain composition has a composition formula (BaαCaβErγO)
_k ) (Ti _1-x Zr _x O ₂ ) (provided that 0.01 ≦ β ≦
0.12, 0.003 ≦ γ ≦ 0.026, 0.99
6 ≦ α + β + γ ≦ 1.020, 0.10 ≦ x ≦ 0.2
A mixture of the basic component represented by 1) and an additive component comprising a Mg compound, a Mn compound, and a Si compound is fired, and the Mg compound is M based on 100 parts by weight of the basic component.
0.04-0.12 parts by weight in terms of gO, the Mn 0.05 to 0.50 part by weight compound in terms of MnO, the Si compound in terms of SiO ₂ .05 to 0. 50
A porcelain capacitor characterized by being contained in parts by weight.