JP2784864B2 - 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. When firing at a high temperature such as 1300 ° C. or more when forming a multilayer ceramic capacitor, expensive palladium (P
It became necessary to use d), which inevitably increased the cost.

[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 1200 ° C. or less 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. The present invention relates to a dielectric porcelain comprising a molar part of a manganese compound and 0.01 to 0.50 molar parts of a germanium 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 germanium compound enables 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 and germanium oxide (Ge) as a compound of germanium
O ₂ ). _{Next, (Ba 1-x Ca x} ) (Ti
_1-y Zr _y) and the values of x and y in O _3, Er
23 kinds of dielectric ceramic materials for 23 kinds of samples were prepared by changing the molar parts of ₂ O ₃ , MnO and GeO ₂ as shown in Table 1.

In the case of manufacturing a capacitor based on the dielectric ceramic material of sample No. 1, x, which represents the molar ratio of the basic components, is 0.05 and y is 0.19. 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 MnO and 0.30 mol part (1.33 g) of GeO ₂ were added, mixed and ground in a ball mill for about 15 hours, and then dried at 150 ° C. for 3 hours to obtain a powder of the porcelain material. Obtained. Then, an organic binder was added to the powder of the porcelain material, and the mixture was stirred.
A disc-shaped compact having a thickness of 0.6 mm and a thickness of 0.6 mm was formed by press molding. Next, the molded body of the porcelain material was
It was fired at 200 ° C. for 2 hours to obtain a dielectric ceramic substrate 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 substrate 12 by a printing method, and then baked at 800 ° C. to form a pair of electrodes 14 and 16, thereby forming the porcelain capacitor 1.
0 was completed. The composition of the porcelain base 12 after firing is substantially the same as the composition of the porcelain material before firing.

Next, the maximum relative permittivity ε _max , tan δ, resistivity ρ and magnetism 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.

In the case of Sample No. 1, as shown in Table 1, ε _max was 19000, tan δ was 0.52%, and ρ was 9.0 × 10 ⁶ MΩ · cm.

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

[0013]

[Table 1]

As is clear from Table 1, Samples No. 1, 2, 5, 8, 10, 1 satisfying the composition specified in the present invention.
The ceramic capacitors of 4, 16, and 18 to 23 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 and a tan δ at 20 ° C.
5% or less, the resistivity ρ at 150 ° C. is 5 × 10 ⁶ MΩ
Satisfies firing at a temperature of not less than cm and not more than 1200 ° C.
Sample Nos. 3, 4, 6, 7, 9, 11, 12, 1 in Table 1
The 3, 15, and 17 porcelain capacitors are other than 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. 16, 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 16, 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 smaller than a 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.
03 mol 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, when MnO is 0.30 mol part, desired characteristics can be obtained. Therefore, Mn
The upper limit of O is 0.30 mol part.

As shown in Sample No. 15, when GeO ₂ is 0, no sintering is performed at 1200 ° C. However, sample NO. 1
As shown in FIG. 6, when GeO ₂ is 0.01 mol part, 1
Firing at 200 ° C. becomes possible. Therefore, the lower limit of GeO ₂ is 0.01 mol part. As shown in Sample No. 17, G
When eO ₂ is 0.5, ε _max becomes less than the desired value.
However, as shown in Sample No. 18, GeO ₂ was 0.50
In the case of the molar part, desired characteristics can be obtained. Therefore, GeO ₂
Is an upper limit of 0.50 mol part.

[0020]

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 It is formed of a composition consisting of ２．０2.0 mol parts of erbium oxide, 0.03-0.30 mol parts of manganese oxide, and 0.01-0.50 mol parts of germanium oxide. . The first and second internal electrodes 22 and 24 are provided on the dielectric ceramic base 20.
And one end of each of them is buried in the dielectric ceramic base 2.
0, and are connected to the first and second external electrodes 26 and 28 provided here. Since the first and second internal electrodes 22 and 24 are opposed to each other via a dielectric ceramic layer that is a part of the dielectric ceramic base 20,
Between these, capacity can be obtained.

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 (palladium) as a conductive material to obtain 4 is applied to a desired pattern and laminated, and furthermore, a conductive paste is layered on top and bottom of this, and these are pressed and bonded. Cut into the desired shape and fire. Thereby, the first and second internal electrodes 2 shown in FIG.
A porcelain base 20 with 2, 24 is obtained. Thereafter, 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 for the multilayer capacitor 18 of FIG. 2, the sample Nos. 1 and 2 of Table 1 are similar to the ceramic capacitor 10 of FIG.
Various samples having the same composition as 2, 5, 8, 10, 14, 16, 18 to 23 were prepared, and their ε _max , tan δ, ρ
Was found to satisfy the target characteristics of the present invention.

[0023]

[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
And 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 GeO ₂ may be mixed, 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

──────────────────────────────────────────────────続 き 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 H01B 3/12

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
It consists of a molar part of a basic component, 0.1 to 2.0 parts by mole of an erbium compound, 0.03 to 0.30 part by mole of a manganese compound, and 0.01 to 0.50 part by mole of a germanium compound. Dielectric porcelain. 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
It consists of a molar part of a basic component, 0.1 to 2.0 parts by mole of an erbium compound, 0.03 to 0.30 part by mole of a manganese compound, and 0.01 to 0.50 part by mole of a germanium compound. A dielectric ceramic capacitor characterized by the above-mentioned.