JP2872513B2 - Dielectric porcelain and porcelain capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric ceramic having a high dielectric constant and a single-layer or multilayer dielectric ceramic capacitor using the same.

[0002]

BACKGROUND ART porcelain the BaTiO ₃ as a dielectric ceramic substrate for magnetic capacitor (barium titanate) as a main component, or a portion of Ba (barium) of BaTiO ₃ Ca
It is known to use a porcelain in which (calcium) is substituted and a part of Ti (titanium) is substituted by Zr (zirconium). It is also known to include Mn (manganese) compounds in these porcelains. The maximum value of the relative permittivity of this type of dielectric porcelain is approximately 14,000.

[0003]

By the way, there is a demand for an increase in capacitance and an improvement in reliability of a dielectric ceramic capacitor. In order to increase the capacitance, it is conceivable to reduce the thickness of the dielectric ceramic layer interposed between the pair of electrodes. However, when the dielectric ceramic layer is made thin, the dielectric strength between the pair of electrodes decreases. As another method for increasing the capacitance, there is a method using a dielectric ceramic having a high relative dielectric constant and a high withstand voltage. However, the conventional BaTiO ₃ -based dielectric porcelain has a limit in the relative dielectric constant and dielectric strength, and has a limit in increasing the capacity.

[0004] Therefore, an object of the present invention is to provide a temperature range from -25 ° C to + 8 ° C.
The maximum value of the relative dielectric constant in the range of 5 ° C. is 14000 or more, the tan δ (dielectric loss) at 20 ° C. is 1.5% or less, and the resistivity at 150 ° C. is 5 × 10 ⁵ MΩ · cm.
An object of the present invention is to provide a dielectric porcelain and a porcelain capacitor using the same.

[0005]

[MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
The present invention relates to (Ba_1-xSr_x) (Ti_1-yZr_y) O₃  Here, x is a numerical value in the range of 0.05 to 0.15, and y is
100 mol consisting of a number in the range 0.10 to 0.24
The basic components of the part,Er ₂O₃ToConvert0.5-2.0
A molar erbium compound;Converted to MnO0.0
3 to 0.30 mole parts of a manganese compound, and
Substantially other componentsIs not included, and
Fired in air, and -25 ° C to + 85 ° C
The maximum value of the relative permittivity in the range of
Tan δ at 20 ° C. is 1.5% or less,
At 5 × 10⁵MΩ · cm or more
The present invention relates to a dielectric porcelain characterized by the following. In addition,
As described in claim 2, the dielectric porcelain of claim 1 is
It can be used as a dielectric porcelain base of a denser.

[0006]

When the dielectric ceramic has the composition specified in the present invention, the maximum relative permittivity ε _max in the range of -25 ° C. to + 85 ° C. is 14000 or more, and tan δ at 20 ° C.
Is 1.5% or less, and the resistivity ρ at 150 ° C. is 5 × 10
⁵ MΩ · cm or more. The erbium (Er) compound contained in the porcelain of the present invention contributes to the improvement of the dielectric strength and the relative dielectric constant. That is, the erbium compound reduces the average particle size of the crystal grains constituting the dielectric ceramic to, for example, 5%.
It has the effect of reducing the size to less than μm. Further, the erbium compound has an action of suppressing the generation of abnormal particles having an average particle size of, for example, 10 times or more of the crystal particles. A dielectric porcelain composed of small crystal grains exhibits a higher dielectric strength than a dielectric porcelain composed of large crystal grains. The size of the crystal grains becomes a problem particularly when the dielectric ceramic between the pair of electrodes in the multilayer ceramic capacitor is made thin. Therefore,
According to the present invention, there is no reduction in dielectric strength and reliability.
Can obtain a relative dielectric constant of 14,000 or more. What
As the relative permittivity increases, the size of porcelain capacitors can be reduced.
Alternatively, the capacity can be increased.

[0007]

First Embodiment Next, in a first embodiment of the present invention, a dielectric ceramic capacitor 10 shown in FIG. 1 was manufactured.
This porcelain capacitor 10 is a disk-shaped dielectric porcelain base 1
2 and a pair of electrodes 14, 1 provided on the pair of main surfaces.
6.

In order to form a ceramic substrate 12 of FIG. 1, first, as zirconate titanate, barium strontium compound _{(Ba 1-x Sr x)} (Ti 1-y Zr y) O
₃ and erbium oxide (Er ₂
O ₃ ) and manganese oxide (Mn) as a manganese compound
O). Next, (Ba _1-x Sr _x ) (Ti
_1-y Zr _y) and the values of x and y in O _3, Er ₂ O ₃
And the molar part of MnO as shown in Table 1 to obtain 2
20 kinds of dielectric ceramic materials for 0 kinds of samples were prepared.

A method of manufacturing a ceramic capacitor according to the dielectric ceramic material of Sample No. 1 will be described below. In the case of sample No. 1, x indicating the molar ratio between the basic components Sr and Zr is 0.0
9. Since y is 0.17, a basic component satisfying the following equation was prepared. (Ba _0.91 Sr _0.09 ) (Ti _0.83 Zr _0.17 ) O _{3 The} basic components are BaCO ₃ (barium carbonate) and SrC so as to satisfy the molar ratio of each atom contained therein.
O ₃ (strontium carbonate) and TiO ₂ (titanium oxide)
And ZrO ₂ (zirconium oxide) were mixed and calcined. Next, 0.50 mole part of Er ₂ O ₃ and 0.18 mole part of MnO were added to 100 mole parts of the basic component, and this was added to about 15 parts by a ball mill.
The mixture was ground and crushed for an hour, and then dried at 150 ° C. for 3 hours to obtain a porcelain material powder. Next, a powder obtained by adding an organic binder to the powder of the porcelain material and stirring the resultant was press-molded to have a diameter of 10 mm and a thickness of 0.4 mm.
Was formed. Next, the formed body of the porcelain material was fired in air (oxidizing atmosphere) at 1300 ° C. for 2 hours to obtain a dielectric porcelain base body 12 shown in FIG. 1 made of a sintered body. Next, a silver paste is applied to one and both main surfaces of the porcelain base 12 by a printing method, and then 800 ° C.
By baking, a pair of electrodes 14 and 16 were formed, and the ceramic capacitor 10 was completed.

Next, the maximum relative permittivity ε _max , tan δ, resistivity ρ, and crystal diameter D of the porcelain substrate of the completed porcelain capacitor
And abnormal particles were measured in the following manner. (A) Maximum relative permittivity Put a porcelain capacitor in a thermostat and keep it at -25 ° C to + 85 ° C.
The maximum capacitance when the temperature was changed until was measured by an impedance analyzer, and the relative permittivity was calculated based on the maximum capacitance and the dimensions of the porcelain base. (B) tan δ (dielectric loss) tan δ at 20 ° C. was measured. (C) Resistivity ρ The ceramic capacitor is set to 150 ° C.
During that time, 100 V DC was applied for 20 seconds to measure the insulation resistance, and the resistivity ρ was calculated from the value of the insulation resistance and the dimensions of the porcelain base 12. (D) Average particle size D The porcelain base 12 was cut and five places were 2,000
The photograph was taken at a magnification of × 5000 or × 5,000, and 200 crystal grains were randomly selected from these photographs, the dimensions were measured, and the average value was determined. (E) Judgment of abnormal particles The porcelain substrate cut for measuring the average particle diameter D was observed with an electron microscope at 100 times, and the presence or absence of crystals having an average particle diameter of 10 times or more was examined. The crystals were regarded as abnormal particles.

In the case of sample No. 1, as shown in Table 1, ε _max is 24200, tan δ is 0.63%, ρ is 8.0 × 10 ⁵ MΩ · cm, and average particle diameter D is 3 .1 μm, and no abnormal particles were present.

In each of Samples Nos. 2 to 20, a porcelain capacitor was formed in the same manner as in Sample No. 1, and ε was formed in a similar manner.
_max , tan δ, ρ, and D were measured, and the presence or absence of abnormal particles was determined. The abnormal particles occurred only in Samples Nos. 3 and 11, and did not occur in other samples.

[0013]

[Table 1]

As is clear from Table 1, Samples Nos. 1, 2, 5, 6, 9, 10, and 10 satisfying the composition specified in the present invention.
The ceramic capacitors of 13, 16 to 20 have a maximum relative dielectric constant ε _max in the range of −25 ° C. to + 85 ° C., which is the target of the present invention, of 14000 or more, and a tan δ at 20 ° C. of 1.5%.
Hereinafter, the resistivity ρ at 150 ° C. is 5 × 10 ⁵ MΩ · c.
m or more, and the average particle diameter D satisfies 5 μm or less. In these cases, no abnormal particles are generated. Sample No. of Table 1
The 3, 4, 7, 8, 11, 12, 14, and 15 porcelain capacitors are other than the present invention because they cannot obtain the characteristics targeted by the present invention.

The reasons for limiting the composition of the dielectric ceramic will now be described. When the value of x is 0.04 as shown in Sample No. 3, abnormal particles are generated. However, when the value of x is 0.05 as shown in Sample No. 6, desired characteristics can be obtained.
Therefore, the lower limit of x is 0.05. As shown in Sample No. 4, when the value of x is 0.16, ρ is less than the desired value. However, as shown in Sample No. 5, the value of x was set to 0.
In the case of 15, desired characteristics can be obtained. Therefore, the upper limit of x is 0.15.

As shown in Sample No. 7, the value of y was 0.09
In this case, tan δ becomes larger than the desired range. However, when the value of y is 0.10 as shown in sample No. 10, desired characteristics can be obtained. Therefore, the lower limit of y is 0.1
0. When the value of y is 0.25 as shown in sample No. 8, ε _max is less than the desired value. However, sample N
As shown in O.9, when y is 0.24, desired characteristics can be obtained. Therefore, the upper limit of y is 0.24.

[0017] As shown in Sample No. 11, when the content of Er ₂ O ₃ is 0.4 mole parts, abnormal particles having an average particle diameter of 10 times or more are generated. However, as shown in sample No. 1, E
When r ₂ O ₃ is 0.50 mol part, no abnormal particles are generated and desired characteristics can be obtained. Therefore, Er
The lower limit of ₂ O ₃ is 0.10 mol part. Sample No. 12
When Er ₂ O ₃ is 2.10 mol parts as shown in FIG.
_max is less than the desired value and tan δ is greater than the desired range. However, as shown in Sample No. 13, Er ₂
When O ₃ is 2.00 mol parts, desired characteristics can be obtained. Therefore, the upper limit of Er ₂ O ₃ is 2.00 mol parts.

As shown in sample No. 14, MnO was 0.0
In the case of 2 mole parts, ρ is less than the desired value. However, when MnO is 0.03 mol part as shown in Sample No. 16, desired characteristics can be obtained. Therefore, the lower limit of MnO is 0.03 mol part. As shown in Sample No. 15, Mn
When O is 0.31, ε _max and ρ are less than desired values. However, as shown in Sample No. 17, MnO was 0.3
In the case of 0 mole part, desired characteristics can be obtained. Therefore,
The upper limit of MnO is 0.30 mol part.

[0019]

FIG. 2 shows a laminated ceramic capacitor 18 according to a second embodiment. The ceramic capacitor 18 includes a dielectric ceramic base 20, a plurality of first internal electrodes 22, a plurality of second internal electrodes 24, and first and second external electrodes 26,2.
8 The dielectric ceramic body 20, similarly to the dielectric ceramic substrate 12 of FIG. 1, the basic components of 100 molar parts consisting of _{(Ba 1-x Sr x)} (Ti 1-y Zr y) O 3, 0.5 It is formed of a composition comprising -2.0 mol parts of erbium oxide and 0.03-0.30 mol parts of manganese oxide. First
The second internal electrodes 22 and 24 are embedded in the dielectric porcelain base 20, respectively, and one end of each of these is embedded in the dielectric porcelain base 20.
Exposed on a pair of side surfaces of the first and second
Are connected to the external electrodes 26 and 28. First and second
Since the internal electrodes 22 and 24 are opposed to each other via a dielectric ceramic layer which is a part of the dielectric ceramic base 20, a capacitance can be obtained between them.

When manufacturing a laminated ceramic capacitor,
As is well known, a plurality of green sheets (unfired ceramic sheets) made of a dielectric ceramic material are prepared. Next, the first and second internal electrodes 22 and 2 are provided on the plurality of green sheets.
The conductive paste for obtaining 4 is applied and laminated in a desired pattern, and furthermore, the conductive paste is layered on the upper and lower sides, and these are pressed and then cut into a desired shape and fired. Thereby, the first and second internal electrodes 22, 2 shown in FIG.
4 is obtained. After that, the first and second external electrodes 26 and 28 are formed by applying and baking a conductive paste to the side surface of the porcelain base 20.

The multilayer capacitor 18 shown in FIG. 2 has the same characteristics as those of the ceramic capacitor 10 shown in FIG.
Various samples having the same composition as 2, 5, 6, 9, 10, 13, 16 to 20 were prepared, and their ε _max , tan δ, ρ,
When D was measured, the target characteristics of the present invention were satisfied. No abnormal particles were generated.

[0022]

[Modifications] The present invention is not limited to the above-described embodiment, and for example, the following modifications are possible. (1) Basic component (Ba _1-x Sr _x ) (Ti _1-y Z
r _y ) To obtain O ₃ , BaTiO ₃ , SrO and Zr
O ₂ and BaT _i O ₃
And SrZrO ₃ in an appropriate ratio, or B
_{a (Ti 1-y Zr y} ) O 3 and SrTiO ₃ and the blending in suitable proportions, or a BaTiO ₃ and SrTiO ₃ and BaZrO ₃ can be blended at an appropriate ratio. (2) The firing temperature can be changed, for example, in the range of 1100 to 1400 ° C. (3) as the starting material of the dielectric ceramic material can be used Er (OH) erbium compounds such as 3 in place of the Er ₂ O _3. (4) Instead of MnO, oxides such as Mn ₃ O ₄ , Mn ₂ O ₃ , MnO ₂ , M
Hydroxides such as n (OH) ₂ and MnO (OH) can be used. (5) The calcination step for obtaining the basic components is omitted, and for example, BaTiO ₃ , SrZrO ₃ , Er ₂ O ₃ and M
It may be mixed with nO, and a molded body of this mixture may be prepared and fired.

[Brief description of the drawings]

FIG. 1 is a front view showing a ceramic capacitor according to a first embodiment.

FIG. 2 is a sectional view showing a laminated ceramic capacitor according to a second embodiment.

[Explanation of symbols]

 12 Dielectric porcelain base 14, 16 Electrodes

Claims (2)

(57) [Claims] (1) (Ba_1-xSr_x) (Ti_1-yZr_y) O₃  Wherein x is a numerical value in the range of 0.05 to 0.15, y is a numerical value in the range of 0.10 to 0.24, andEr ₂ O₃ Converted to0.5 to 2.0 mol parts of Erbius
CompoundConverted to MnO 0.03 to 0.30 mol part of manganese
Consisting of a compound andSubstantially other componentsIncluding
And fired in the air,
And the maximum relative dielectric constant in the range of −25 ° C. to + 85 ° C.
Value is 14000 or more and tan δ at 20 ° C. is 1.5
% Or less and the resistivity at 150 ° C. is 5 × 10⁵M
A dielectric porcelain characterized by being Ω · cm or more. 2. A dielectric porcelain base and the dielectric porcelain base
A porcelain condenser comprising at least two electrodes in contact
A dielectric element, wherein the dielectric porcelain base comprises: (Ba)_1-xSr_x) (Ti_1-yZr_y) O₃  Wherein x is a numerical value in the range of 0.05 to 0.15, y is a numerical value in the range of 0.10 to 0.24, andEr ₂ O₃ Converted to0.5 to 2.0 mol parts of Erbius
CompoundConverted to MnO 0.03 to 0.30 mol part of manganese
Consisting of a compound andSubstantially other componentsIncluding
And fired in the air,
And the maximum relative dielectric constant in the range of −25 ° C. to + 85 ° C.
Value is 14000 or more and tan δ at 20 ° C. is 1.5
% Or less and the resistivity at 150 ° C. is 5 × 10⁵M
Dielectric porcelain condenser characterized by being Ω · cm or more
Sensor.