JP3089833B2 - Dielectric ceramic composition for temperature compensation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature-compensating dielectric ceramic composition, and more particularly to a temperature-compensating dielectric ceramic composition used as a material for a dielectric ceramic of a multilayer capacitor.

[0002]

2. Description of the Related Art Heretofore, as this kind of dielectric ceramic composition for temperature compensation, there has been an MgTiO ₃ —CaTiO ₃ based composition.

[0003]

However, MgT
The iO ₃ -CaTiO ₃ based ceramics with the composition of, the firing temperature is as high as 1300 ° C. or more, is reduced further calcined at low oxygen partial pressure neutral or reducing, has the property of semiconductive I was Therefore, when such a composition is used as a material for a multilayer capacitor or the like,
As a material for the internal electrode, a noble metal such as Pt or Pd, which does not melt at the temperature at which the dielectric ceramic material sinters and does not oxidize even under a high oxygen partial pressure that does not turn the dielectric ceramic material into a semiconductor, must be used. Did not. Therefore, it has been a great hindrance to reducing the price of the manufactured multilayer capacitor.

Therefore, in order to solve the above-mentioned problem, it has been desired to use an inexpensive base metal such as Ni or Cu as a material for the internal electrodes. However, when such a base metal is used as a material for an internal electrode and fired under a conventional oxidizing atmosphere, the electrode material is oxidized or melted. Therefore, since such a base metal is used as a material for an internal electrode, it does not turn into a semiconductor even when fired at a low temperature in a neutral or reducing atmosphere having a low oxygen partial pressure, and is sufficiently used as a dielectric material for a capacitor. There is a need for a dielectric material having an excellent specific resistance and excellent dielectric properties.

A dielectric porcelain composition for solving this kind of problem is disclosed in Japanese Patent Application Laid-Open No. 1-102806. Since this dielectric porcelain composition can be fired in neutral and reducing atmospheres with low oxygen partial pressure,
Using this, a multilayer capacitor for temperature compensation using a base metal such as Ni or Cu as an internal electrode can be manufactured.
However, in the dielectric porcelain composition disclosed in JP-A-1-102806, the above problems can be solved with respect to the firing temperature and the temperature coefficient of the dielectric constant, but the dielectric constant ε is 1
And a dielectric loss tan δ of 0.1 at 1 MHz.
It is as large as 05% or more.

[0006] Therefore, the main object of the present invention is to provide a neutral or reducing atmosphere having a low oxygen partial pressure.
Sintered at 200 ° C. or less, not reduced, has a dielectric constant ε of 20 or more, and has an absolute value of a temperature coefficient of capacitance of 60
ppm / ° C. or less, dielectric loss tan δ is 0.02% or less,
A specific resistance at 20 ° C. of 1 × 10 ¹³ Ωcm or more;
An object of the present invention is to provide a dielectric ceramic composition for temperature compensation, which can use an inexpensive metal such as Cu as a material for an internal electrode.

[0007]

SUMMARY OF THE INVENTION The present invention provides aCaNb
₂ O ₆ -bZnNb ₂ O ₆ -cZnO-dCaTiO ₃
A dielectric ceramic composition for temperature compensation having a composition represented by the following formula:
0.10 ≦ a ≦ 0.60, 0.05 ≦ b ≦ 0.60,
A temperature-compensating dielectric porcelain composition in the range of 0.15 ≦ c ≦ 0.75 and 0.01 ≦ d ≦ 0.20 and satisfies the relationship of a + b + c + d = 1. Furthermore, the main component 100
B ₂ O ₃ , SiO ₂ , L
0.1 to 20 parts by weight of at least one metal oxide selected from i ₂ O may be added.

[0008]

According to the present invention, sintering is performed at a low temperature of 1200 ° C. or less in a reducing atmosphere, the absolute value of the temperature coefficient of capacitance is 60 ppm / ° C. or less, and the dielectric loss tan
δ is 0.02% or less, and the specific resistance at 20 ° C. is 1
× can be obtained temperature compensating dielectric ceramic composition having a 10 ¹³ [Omega] cm or more properties. Therefore, if this dielectric ceramic composition for temperature compensation is used as a material for a multilayer capacitor, a base metal such as Cu can be used as a material for an internal electrode. Therefore, it is possible to eliminate an increase in the cost of the electrodes due to the increase in the capacity of the multilayer capacitor, and to provide a low-cost multilayer capacitor. Also, since the dielectric loss tan δ is small, it can be used as a material for microwave LC filters, RF modules and the like.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the embodiments.

[0010]

EXAMPLE First, CaNb ₂ O ₆ , ZnNb ₂ O ₆ , C
CaCO ₃ as the starting material of aTiO _3, ZnO, Nb
₂ O ₅ and TiO ₂ were prepared. These raw materials are weighed according to each composition, wet-mixed with a ball mill, and dried, and
Calcination was performed at 0 to 1200 ° C. for 3 hours to obtain a main component material.

Further, a material containing at least one kind of metal oxide among B ₂ O ₃ , SiO ₂ and Li ₂ O is weighed so as to have a compounding ratio shown in Table 1, and these are wet-mixed by a ball mill. After pulverization, the mixture was evaporated to dryness and melted at 1000 ° C. in a natural atmosphere. In addition, 1 ball mill
After wet pulverization to a size of not more than μm, the mixture was evaporated to dryness to obtain an accessory component.

[0012]

[Table 1]

The raw materials thus obtained were weighed so as to have the composition shown in Table 2 and wet-mixed with a ball mill for 16 hours. Then, 5 parts by weight of a vinyl acetate-based binder was added as a binder, and wet-mixed with a ball mill. To obtain a mixture.

[0014]

[Table 2]

Further, after evaporating and drying the mixture,
The particles were sized to obtain a powder material. 2 to
Pressurized with pressure of n / cm ² , diameter 20mm, thickness 1.0
A molded product was obtained by molding into a disk having a thickness of 2 mm. The molded product was placed in an alumina box made of zirconia powder as a ground powder, and the vinyl acetate binder was burned at 500 ° C. for 2 hours in a natural atmosphere. After that, the volume ratio of H ₂ : N ₂ =
In a reducing atmosphere of 3: 100, the molded article is 900
The device was fired at 〜1350 ° C. for 2 hours to obtain an element. An In-Ga alloy is applied to both surfaces of the obtained device to form electrodes,
A capacitor was prepared as a sample.

For the obtained sample, dielectric constant ε, dielectric loss tan δ, temperature coefficient of capacitance α (ppm / ° C.), 2
The specific resistance ρ ₂₀ (Ωcm) at 0 ° C. was measured. In addition,
For the dielectric loss tan δ, 1 MHz, 1 Vrms,
The measurement was performed at 20 ° C. In addition, the temperature coefficient of capacitance T
C (ppm / ° C.) was determined from the capacitance C _{20 at 20} ° C. and the capacitance C _{85 at} 85 ° C. by the following equation.

[0017]

(Equation 1)

Further, the specific resistance ρ ₂₀ (Ωc at 20 ° C.)
m) was determined from a current value flowing when a DC voltage of 500 V was applied at 20 ° C. Table 3 shows the results. In Tables 2 and 3, those marked with * are out of the scope of the present invention, and the others are within the scope of the present invention.

[0019]

[Table 3]

Next, the reason why the numerical values of the main component and the subcomponent of the dielectric ceramic composition for temperature compensation of the present invention are limited will be described. As in sample No. 6, the main component aCaNb ₂
When c of O ₆ -bZnNb ₂ O ₆ -cZnO-dCaTiO ₃ is larger than 0.75, the dielectric loss tan δ is 0.1.
02%, the absolute value of the temperature coefficient of capacitance is greater than 60 ppm / ° C., and the specific resistance is 1 × 1
It is not preferable because it is lower than 0 ¹³ Ωcm. When a of the main component is smaller than 0.10 as in Sample No. 7, the specific resistance is less than 1 × 10 ^13, which is not preferable. When c as the main component is smaller than 0.15 as in Sample No. 8, the firing temperature exceeds 1200 ° C., and the absolute value of the temperature coefficient of the capacitance becomes undesirably higher than 60 ppm / ° C. When b as the main component is smaller than 0.05 as in Sample No. 9, the firing temperature exceeds 1200 ° C., the absolute value of the temperature coefficient of the capacitance becomes larger than 60 ppm / ° C., and the dielectric loss tan δ is 0. 0.02%, which is not preferable. When d of the main component is larger than 0.20 as in the sample No. 11, the firing temperature exceeds 1200 ° C., and the absolute value of the temperature coefficient of the capacitance becomes larger than 60 ppm / ° C., which is not preferable.

As shown in Sample No. 14, when the addition amount of the sub-component of the A series shown in Table 1 is more than 20 parts by weight, the dielectric constant ε
Is smaller than 20, and the dielectric loss tan δ is 0.02%
It is not preferable because it becomes larger. As shown in Sample No. 17, when the addition amount of the sub-component of the B series shown in Table 1 is more than 20 parts by weight, the dielectric constant ε is smaller than 20, and
It is not preferable because nδ is greater than 0.02%, the absolute value of the temperature coefficient of capacitance is greater than 60 ppm / ° C., and the specific resistance is less than 1 × 10 ¹³ Ωcm.

On the other hand, according to the present invention, sintering is performed at a low temperature of 1200 ° C. or less in a reducing atmosphere, the absolute value of the temperature coefficient of capacitance is 60 ppm / ° C. or less, and the capacitance tan δ is 0%. 0.02% or less, and a dielectric ceramic composition for temperature compensation having characteristics of a specific resistance of 1 × 10 ¹³ Ωcm or more at 20 ° C. can be obtained. Therefore,
If this dielectric ceramic composition for temperature compensation is used as a material for a multilayer capacitor, a base metal such as Cu can be used as a material for an internal electrode. Therefore, it is possible to eliminate an increase in the cost of the electrodes due to the increase in the capacity of the multilayer capacitor, and to provide a low-cost multilayer capacitor. Further, since the capacitance tanδ is small,
It can be used as a material for microwave LC filters and RF modules.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-57-145211 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01G 4/00-4/40 H01G 13 / 00-13/06

Claims (2)

(57) [Claims] 1. aCaNb ₂ O ₆ -bZnNb ₂ O _6-
A temperature-compensating dielectric porcelain composition having a composition represented by cZnO-dCaTiO ₃ as a main component, wherein a, b, c, and d are each a mole fraction, and 0.10 ≦ a ≦ 0.600. 0.05 ≦ b ≦ 0.60 0.15 ≦ c ≦ 0.75 0.01 ≦ d ≦ 0.20 and satisfies the relationship of a + b + c + d = 1.
A dielectric ceramic composition for temperature compensation. 2. Addition of 0.1 to 20 parts by weight of at least one kind of metal oxide selected from B ₂ O ₃ , SiO ₂ and Li ₂ O as an auxiliary component to 100 parts by weight of the main component. The dielectric ceramic composition for temperature compensation according to claim 1, wherein