JP3291748B2 - 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 dielectric ceramic composition for temperature compensation, and more particularly to, for example, a multilayer capacitor and a multilayer LC.
The present invention relates to a dielectric ceramic composition for temperature compensation used as a dielectric ceramic of a filter.

[0002]

2. Description of the Related Art Conventionally, as this kind of dielectric ceramic composition for temperature compensation, a MgTiO ₃ —CaTiO ₃ series ceramic composition has been used.

[0003]

However, MgT
iO ₃ In -CaTiO ₃ based ceramic composition, as high as the sintering temperature is 1300 ° C. or higher, further, a problem that the semiconductive ceramic is reduced when fired at low oxygen partial pressure neutral or reducing Had a point.

For this reason, a metal that does not melt at a temperature at which the dielectric ceramic material sinters and does not oxidize even when fired under a high oxygen partial pressure at which the dielectric ceramic material does not turn into a semiconductor must be used as a material for the internal electrodes. Must. For this reason, when using a conventional material as the dielectric porcelain of the multilayer capacitor, expensive platinum or palladium which has a high melting point and is hardly oxidized at a high temperature must be used as a material of the internal electrode.
This hindered the cost reduction of multilayer capacitors.

Therefore, in order to solve the above problems,
It has been desired that the material of the internal electrodes be changed from expensive noble metals to inexpensive base metals such as nickel and copper. However, using such a base metal as the material of the internal electrode,
When firing under conventional conditions, the electrode material is oxidized or melted. Therefore, in order to use such a base metal as a material for the 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 as a dielectric ceramic material for a capacitor. There has been a need for a dielectric ceramic composition having sufficient specific resistance and excellent dielectric properties.

A dielectric porcelain composition for solving this kind of problem is disclosed in JP-A-1-102806 and the like. This dielectric ceramic composition can be fired in a neutral or reducing atmosphere having a low oxygen partial pressure. Therefore, a multilayer capacitor for temperature compensation using a base metal such as nickel or copper as a material of an internal electrode can be provided by using this dielectric ceramic composition. But,
This dielectric porcelain composition solves the above-mentioned problems with respect to the firing temperature and the temperature coefficient of the dielectric, but has a Q value of 1
It was as small as 2000 or less at MHz.

[0007] Therefore, the main object of the present invention is to provide a neutral or reducing atmosphere having a low oxygen partial pressure.
Sintering without reduction at a low temperature of 050 ° C. or less, and an absolute value of a temperature coefficient of a dielectric constant of 50 ppm / ° C. or less,
A dielectric ceramic composition having a Q value of 2500 or more at 1 MHz and a specific resistance value of 1 × 10 ¹² Ωcm or more at 20 ° C. can be obtained, and a base metal such as copper can be used as an internal electrode. It is to provide.

[0008]

SUMMARY OF THE INVENTION The present invention provides a TiO ₂ 2
_{2 to} 43 parts by weight, 38 to 58 parts by weight of ZrO ₂ , SnO ₂
9 to 26 parts by weight as a main component, and B ₂ O ₃ , SiO ₂ , Li
It is a dielectric ceramic composition for temperature compensation to which 5 to 35 parts by weight of a metal oxide containing at least one selected from ₂ O is added.

[0009]

According to the present invention, sintering is performed at a low temperature of 1050 ° C. or less without reduction in a neutral or reducing atmosphere having a low oxygen partial pressure, and the absolute value of the temperature coefficient of capacitance is obtained. Is 50 ppm / ° C or less and the Q value is 25 at 1 MHz.
00 or more, and the specific resistance at 20 ° C. is 1 × 10 ¹²
A temperature-compensating dielectric porcelain composition capable of obtaining a dielectric porcelain having a characteristic of Ωcm or more is obtained.

Therefore, when this dielectric ceramic composition for temperature compensation is used as a material for a multilayer capacitor, a base metal such as copper can be used as 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. The dielectric ceramic obtained from the temperature-compensating dielectric ceramic composition has a high Q value and a small temperature coefficient of the dielectric constant. Therefore, by using an electrode having high conductivity such as silver, copper, or gold, it can be used as a material for a laminated LC filter, an RF module, or the like used in a microwave region.

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

[0012]

EXAMPLES First, as a starting material of a main component, a purity of 99.
5% or more of TiO ₂ , ZrO ₂ , and SnO ₂ were blended so as to have the blend ratios shown in Table 1.

[0013]

[Table 1]

Further, B ₂ O ₃ , S
iO ₂ , Li ₂ O, BaO, ZnO, CuO, MnO,
CaO was prepared. These materials were weighed to the ratios shown in Table 2, wet-mixed in a ball mill, pulverized, evaporated to dryness, and dried in a natural atmosphere at 1000 wt.
Melted at ℃. In addition, the molten material is
BR> 1 μm or less, then dry by evaporation
Two types of subcomponents, a sequence and a B sequence, were obtained.

[0015]

[Table 2]

The obtained main component and subcomponent were blended so as to have the ratio shown in Table 1 to obtain a blended raw material.

5 parts by weight of a vinyl acetate-based binder was added as a binder to this compounding raw material, and the mixture was wet-mixed with a ball mill to obtain a mixture. Further, after evaporating and drying the mixture, the mixture was sized to obtain a powder raw material. 2 ton /
It was molded into a disk having a diameter of 20 mm and a thickness of 1.0 mm under a pressure of cm ² to obtain a molded product.

Next, the disc-shaped molded product was placed in an alumina box using zirconia powder as a powder, and the vinyl acetate binder was burned at 500 ° C. for 2 hours in a natural atmosphere. Then, in a reducing gas atmosphere with a volume ratio of N ₂ : H ₂ = 3: 100, the disc-shaped molded product is 900-1.
The element was obtained by firing at 050 ° C. for 2 hours. Further, an In-Ga alloy was applied to both main surfaces of the obtained device to form electrodes, thereby preparing a sample (capacitor).

Then, for the obtained sample, the dielectric constant ε, Q value, temperature coefficient of dielectric constant α (ppm / ° C.), 20 ° C.
Each characteristic of the specific resistance ρ ₂₀ (Ωcm) was measured.

The dielectric constant ε and the Q value are set at a frequency of 1 MHz.
z, voltage 1 Vrms, temperature 20 ° C.
Further, the temperature coefficient α (ppm / ° C.) of the dielectric constant is expressed by a capacitance C _{20 at 20} ° C. and a capacitance C _{85 at} 85 ° C.
From the following equation. α (ppm / ° C.) = {(C ₈₅ −C ₂₀ ) / C ₂₀ } × {1 / (85−20)} × 10 ⁶

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.

[0022]

[Table 3]

In Tables 1 and 3, those marked with an asterisk are outside the scope of the present invention, and the others are within the scope of the present invention.

The composition of the main components of each sample shown in Table 1 is shown in FIG. 1 as a three-component composition diagram. ○ in this drawing
The number with the mark indicates each sample number.

Further, in FIG. 1, regions indicating the composition ratios of the main components of the composition of the present invention are represented by composition points A, B, C, D,
It is shown as a polygon with E and F as vertices.

The composition according to the present invention contains B ₂ O ₃ , S
iO _2, Li ₂ metal oxide containing at least one selected from the O is added 5 to 35 parts by weight.

Next, the reason why the numerical values of the components of the dielectric ceramic composition for temperature compensation according to the present invention are limited as described above will be described.

If the content of TiO ₂ is less than 22 parts by weight, the sinterability is poor, and even if it is fired at a temperature of 1050 ° C., a dense sintered body cannot be obtained. On the other hand, if TiO ₂ exceeds 43 parts by weight, the temperature coefficient becomes large and the specific resistance becomes less than 10 ¹² Ωcm, which is not preferable (see Sample No. 1).

If ZrO ₂ is less than 38 parts by weight, the temperature coefficient is undesirably large. Further, when ZrO ₂ is 58
If the amount is more than 10 parts by weight, the sinterability is poor, and even if firing at a temperature of 1050 ° C., a dense sintered body cannot be obtained, which is not preferable (see Sample No. 11).

If SnO ₂ is less than 9 parts by weight or more than 26 parts by weight, the temperature coefficient is increased and the specific resistance is less than 10 ¹² Ωcm, which is not preferable (see Sample No. 14).

If the amount of the auxiliary component of the A series is less than 5 parts by weight with respect to 100 parts by weight of the main component, the sinterability is poor, and
Firing at a temperature of 50 ° C. is not preferable because a dense sintered body cannot be obtained (see Sample No. 18). On the other hand, if the amount of the auxiliary component in the A series exceeds 35 parts by weight, the Q value becomes 25%.
It is not preferable because it is less than 00 (see Sample No. 21).

If the amount of the B-series subcomponent is less than 5 parts by weight with respect to 100 parts by weight of the main component, the sinterability is poor, and
Firing at a temperature of 50 ° C. is not preferable because a dense sintered body cannot be obtained. In addition, the addition amount of the auxiliary component of the B series is 3
If it exceeds 5 parts by weight, the Q value is less than 2500 and the specific resistance is less than 10 ¹² Ωcm, which is not preferable (see Sample No. 25).

Although the metal oxide powder is used as an auxiliary component in the above embodiment, a solution may be added. In addition, the subcomponents are used by vitrifying each material by melting and pulverization, but may be added to the main component as it is.

[Brief description of the drawings]

FIG. 1 is a three-component composition diagram showing the mixing ratio of the main components of the composition of the present invention.

Continuation of the front page (56) References JP-A-5-182523 (JP, A) JP-A-58-18808 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01B 3 / 12 304 H01B 3/12 320 H01B 3/12 338 H01G 4/12 358 C04B 35/46

Claims (1)

(57) [Claims] 1. ZrO ₂ , 22 to 43 parts by weight of TiO ₂
8 to 58 parts by weight of SnO _{2 and} 9 to 26 parts by weight of SnO _2.
A dielectric ceramic composition for temperature compensation, comprising 5 to 35 parts by weight of a metal oxide containing at least one selected from O ₃ , SiO ₂ and Li ₂ O.