JP2779740B2 - 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. Further, when firing at a high temperature of, for example, 1300 ° C. or more when forming a laminated magnetic capacitor, it is necessary to use expensive palladium (Pd) as a material for the internal electrodes, which inevitably increases the cost. Became.

[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 ⁶ MΩ · c.
It is an object of the present invention to provide a dielectric ceramic which can be obtained by firing at a temperature of not less than 1200 ° C. and a ceramic capacitor using the same.

[0005]

The present invention Means for Solving the Problems] To achieve the above object, where _{(Ba 1-x Ca x)} (Ti 1-y Zr y) O 3, x is 0.01 to 0.10 Where y is a number in the range of 0.10 to 0.24, 100 mole parts of the basic component, 0.1 to 2.0 mole parts of the erbium compound, and 0.03 to 0.30. Mole parts of a manganese compound, 0.03 to 0.40 mole parts of a zinc compound,
The present invention relates to a dielectric porcelain comprising 1 to 0.20 mol parts of a silicon compound. As described in claim 2, the dielectric ceramic of claim 1 can be used as a dielectric ceramic base of a ceramic capacitor.

[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 the tan δ at 20 ° C. is 1.5% or less. Ρ at 150 ° C. is 5 × 10 ⁶
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 μm.
It has the effect of reducing the size to m or less. 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. The zinc compound and the silicon compound enable firing at a low temperature of 1200 ° C. or less. When the firing temperature is 1200 ° C. or lower, the electrode material of the capacitor can be a mixture of Ag and Pd, and the cost can be reduced.

[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 calcium compound and _{(Ba 1-x Ca x)} (Ti 1-y Zr y) O 3, oxides as erbium compound Erbium (Er ₂ O ₃ )
And manganese oxide (MnO) as a manganese compound, zinc oxide (ZnO) as a zinc compound, and silicon oxide (SiO ₂ ) as a silicon compound. next,
_{(Ba 1-x Ca x)} (Ti 1-y Zr y) x in O ₃
And y, and Er ₂ O ₃ , MnO, ZnO and SiO
_By changing the molar part of ₂ as shown in Table 1, 23 kinds of dielectric ceramic materials for 23 kinds of samples were prepared.

[0009]

[Table 1]

In the case where a capacitor according to the dielectric ceramic material of sample No. 1 is manufactured, since the molar ratio x of the basic components is 0.05 and y is 0.19, the basic components satisfying the following equation are satisfied. Was prepared. (Ba _0.95 Ca _0.05 ) (Ti _0.81 Zr _0.19 ) O _{3 The} basic components are BaCO ₃ (barium carbonate), CaCO ₃ (calcium carbonate), TiO ₂ and ZrO ₂ so as to satisfy the molar ratio of each element. And calcined. Next, 100 mole parts (100
0.30 mol part (4.
85 g) of Er ₂ O ₃ and 0.10 mol part (0.30 g)
Of 0.30 mol part (1.03 g) of ZnO and 0.02 mol part (0.05 g) of SiO ₂ ,
This was mixed and pulverized for about 15 hours in a ball mill, and then dried at 150 ° C. for 3 hours to obtain a powder of a porcelain material. Next, a disc-shaped molded body having a diameter of 10 mm and a thickness of 0.6 mm was formed by press molding using a mixture obtained by adding an organic binder to the powder of the porcelain material and stirring the mixture. Next, the formed body of the porcelain material was fired in air at 1200 ° C. for 2 hours to obtain a dielectric porcelain base 12 shown in FIG. 1 made of a sintered body. Next, a frit-free silver paste is applied to one and both main surfaces of the porcelain base 12 by a printing method, and then baked at 800 ° C. to form a pair of electrodes 14 and 16 to form a porcelain capacitor 10. Was completed.

Next, the maximum relative permittivity ε _max , tan δ and resistivity ρ of the completed ceramic capacitor 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. Table 2 shows the characteristics of each sample.

[0012]

[Table 2]

In the case of sample No. 1, as shown in Table 2, ε _max was 23500, tan δ was 0.33%, and ρ was 8.0 × 10 ⁶ MΩ · cm.

In sample Nos. 2 to 23, a porcelain capacitor was formed in the same manner as in sample No. 1, and ε was formed in the same manner.
_{The max} , tan δ, and ρ were measured.

As is clear from Tables 1 and 2, Samples No. 1, 2, 5, 8, 1 satisfying the composition specified in the present invention.
The porcelain capacitors 0, 14, 16, 18, 20, 22, and 23 have a maximum relative dielectric constant ε _max in the range of −25 ° C. to + 85 ° C. targeted by the present invention of 1400 or more, 20
Tan δ of 1.5 ° C or less, resistivity ρ at 150 ° C
Satisfy firing at a temperature of 5 × 10 ⁶ MΩ · cm or more and 1200 ° C. or less. Samples Nos. 3, 4, 6, in Tables 1 and 2
The porcelain capacitors 7, 9, 11, 12, 13, 15, 17, 19, and 21 are not the present invention because the characteristics desired by the present invention cannot be obtained.

The reasons for limiting the composition of the dielectric ceramic will now be described. When the value of x is 0, as shown in sample No. 3, ε
_max is less than the desired value. However, when the value of x becomes 0.01 as shown in Sample No. 18, desired characteristics are obtained. Therefore, the lower limit of x is 0.01. As shown in sample No. 4, when the value of x becomes 0.12, ε _max becomes less than the desired value. However, when the value of x is 0.10 as shown in Sample Nos. 5 and 15, desired characteristics can be obtained. Therefore, the upper limit of x is 0.10.

As shown in Sample No. 6, the value of y was 0.08
In this case, ε _max is smaller than the desired value, and tan δ is larger than the desired range. However, when the value of y is 0.10 as shown in sample No. 2, desired characteristics are obtained.
Therefore, the lower limit of y is 0.10. When the value of y is 0.25 as shown in sample No. 7, ε _max is less than the desired value. However, as shown in sample No. 8, y was 0.2
At 4, the desired characteristics are obtained. Therefore, the upper limit of y is 0.24.

As shown in Sample No. 9, when Er ₂ O ₃ is 0, the resistivity ρ becomes less than the desired value. However, sample N
As shown in O. 10, when 0.10 mol part of Er ₂ O ₃ is included, desired characteristics can be obtained. Therefore, Er ₂
The lower limit of O ₃ is 0.10 mol part. As shown in Sample No. 11, when Er ₂ O ₃ was 2.10 mol parts, ε _max
Is less than the desired value. However, when Er ₂ O ₃ is 2.00 mol parts as shown in Sample No. ₂ , desired characteristics can be obtained. Therefore, the upper limit of Er ₂ O ₃ is 2.00.
It is a molar part.

As shown in sample No. 12, 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. 2, desired characteristics can be obtained. Therefore, the lower limit of MnO is 0.1.
3 mole parts. As shown in Sample No. 13, when MnO is 0.32, ε _max and ρ are less than desired values. However, as shown in Sample No. 14, MnO was 0.1%.
In the case of 30 mole parts, desired characteristics can be obtained. Therefore, the upper limit of MnO is 0.30 mol part.

As shown in sample No. 15, ZnO was 0.0
In the case of 1 mole part, a sintered body cannot be obtained by firing at 1200 ° C. However, as shown in sample No. 16, Z
When nO is 0.03 mol part, desired characteristics can be obtained. Therefore, the lower limit of ZnO is 0.03 mol part. As shown in Sample No. 17, when ZnO was 0.42 mol parts, ε _max was less than the desired value. However, sample N
As shown in O. 18, when ZnO is 0.40 mol part, desired characteristics can be obtained. Therefore, the upper limit of ZnO is 0.40 mol part.

As shown in Sample No. 11, when SiO ₂ is 0, a sintered body cannot be obtained by firing at 1200 ° C. However, as shown in sample No. 20, SiO ₂ was 0.01%.
In the case of a molar part, desired characteristics cannot be obtained. Therefore, the lower limit of SiO ₂ is 0.01 mol part. Sample N
SiO ₂ as shown in O. 21 is the ρ is less than a desired value in the case of 0.21 molar parts. However, when SiO ₂ is 0.2
In the case of 0 mole parts, desired characteristics can be obtained. Therefore, the upper limit of SiO ₂ is 0.20 mol part.

[0022]

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, first and second external electrodes 26,
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 Ca x)} (Ti 1-y Zr y) O 3, 0.1 Erbium oxide, 0.03 to 0.30 mol part of manganese oxide, 0.03 to 0.40 mol part of zinc oxide and 0.01 to 0.20 mol part And a silicon oxide. The first and second internal electrodes 22 and 24 are respectively buried in the dielectric porcelain base 20, and one ends thereof are exposed on a pair of side surfaces of the dielectric porcelain base 20, and the first and second internal electrodes 22 and 24 are provided here. External electrode 2
6, 28. First and second internal electrodes 2
The capacitors 2 and 24 are opposed to each other via a dielectric ceramic layer which is a part of the dielectric ceramic substrate 20, so that 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.
A conductive paste using a mixture of Ag (silver) and Pd (N palladium) as a conductive material to obtain 4 is applied in a desired pattern and laminated, and further, green sheets are laminated on the upper and lower sides thereof, and after these are pressed, Then, cutting into a desired shape and firing. Thereby, the porcelain base 20 with the first and second internal electrodes 22 and 24 shown in FIG. 2 is obtained. After that, the first and second external electrodes 26 and 28 are formed by applying and baking a conductive paste (Ag paste) to the side surface of the porcelain base 20.

As with the ceramic capacitor 10 of FIG. 1, the multilayer capacitors 18 of FIG.
2, 5, 8, 10, 14, 16, 18, 20, 22, 2,
Various samples having the same composition as in No. 3 were prepared, and their ε _max , tan δ, and ρ were measured. As a result, the target characteristics of the present invention were satisfied.

[0025]

[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 Ca x)} (Ti 1-y Z
To obtain _{r y) O 3, BaT i} O 3 and CaZrO ₃
Blending the door at an appropriate ratio, or Ba (Ti _{1- y} Z
r _y ) O ₃ and CaTiO ₃ can be blended at an appropriate ratio, or BaTiO ₃ , CaTiO ₃ and BaZrO ₃ can be blended at an appropriate ratio. (2) The firing temperature can be changed, for example, in the range of 1000 to 1200 ° C. (3) An erbium compound such as Er (OH) ₃ can be used instead of Er ₂ O ₃ as a starting material of the dielectric ceramic material. Incidentally, when obtaining the porcelain of the present invention contain in the range of 0.1 to 2.0 molar parts in terms of the erbium compound in 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 , CaZrO ₃ , Er ₂ O ₃ , M
nO, and ZnO, was mixed with SiO _2, it may be fired to create a compact of the mixture.

[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

────────────────────────────────────────────────── ─── Continued on the front page (72) Katsuyuki Horie, Inventor Taiyo Yuden Co., Ltd., 6-16-20 Ueno, Taito-ku, Tokyo (58) Field surveyed (Int.Cl. ⁶ , DB name) H01G 4/12

Claims (2)

(57) [Claims] [Claim 1] _{(Ba 1-x Ca x)} (Ti 1-y Zr y) O 3 wherein, x represents a number in the range from 0.01 to 0.10, y is the 0.10 to 0.24 A number in the range, consisting of 100
Mole parts of the basic component, 0.1 to 2.0 mole parts of the erbium compound, 0.03 to 0.30 mole part of the manganese compound, 0.03 to 0.40 mole part of the zinc compound, A dielectric ceramic comprising 0.11 to 0.20 mol parts of a silicon compound. 2. A ceramic capacitor comprising a dielectric porcelain base and at least two electrodes in contact with said dielectric porcelain base, wherein said dielectric porcelain base comprises: (Ba _{1 -x} Ca _x ) (Ti here _{1-y Zr y) O 3} , x is a number in the range from 0.01 to 0.10, y consists of numbers, in the range of from 0.10 to 0.24 100
Mole parts of the basic component, 0.1 to 2.0 mole parts of the erbium compound, 0.03 to 0.30 mole part of the manganese compound, 0.03 to 0.40 mole part of the zinc compound, A dielectric ceramic capacitor comprising 0.11 to 0.20 mol parts of a silicon compound.