JP2795562B2 - Dielectric porcelain composition - 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 which can be fired at a low temperature, has a large relative dielectric constant, has a large unloaded Q in a microwave region, and has a small temperature change rate of a resonance frequency. It is.

[0002]

2. Description of the Related Art In recent years, there has been a demand for miniaturization of mobile communication devices such as automobile telephones and portable telephones utilizing radio waves in the microwave band, and devices with the development of satellite broadcasting. For this purpose, individual components that make up the equipment must be miniaturized. One of the means is to use a filter using a dielectric material as a band-pass filter (this industry).
Then, it is generally called an LC filter. ) Has been proposed.

In order to manufacture a small LC filter, a material having a high dielectric constant is required. In addition, it is necessary that the unloaded Q in the microwave region is large, the temperature change rate of the dielectric constant is small, and the firing temperature is low for selection of the conductor material to be used and simultaneous firing. on the other hand,
Since the conductivity of the conductor is required to be small, Cu
It is desirable to use Ag or Ag. When Cu and Ag are compared, the conductivity is slightly higher in Ag, but Ag causes migration in the presence of moisture, which is problematic in terms of reliability. Therefore, it is desirable that Cu can be used as the conductive material. In order to use Cu, it is necessary that the dielectric properties of the dielectric do not deteriorate even when firing in an atmosphere in which Cu is not oxidized.

[0004]

However, conventionally,
Ba (Mg _1/3 T) used in the microwave region
Dielectric materials such as a _2/3 ) O ₃ and Ba (Zn _1/3 Ta _1/3 ) O ₃ have firing temperatures as high as 1300 ° C. or higher, and Cu and Ag.
Cannot be used as an electrode, and conversely, a material having a low firing temperature used for a substrate or the like has a small dielectric constant of 10 or less and is difficult to use as a small LC filter material.

In order to solve the above-mentioned problems of the prior art, the present invention provides a dielectric material which can be fired at a low temperature, has a large relative dielectric constant, has a large unloaded Q in the microwave region, and has a small temperature change rate of the resonance frequency. It is an object to provide a body porcelain composition.

[0006]

In order to achieve this object, the dielectric ceramic composition of the first invention of the present invention has a main component represented by the general formula (Bi ₂ O ₃ ) _X (Nb ₂ O ₅ ) _{1 In the} porcelain composition represented by _-X , X is in the range of 0.48 ≦ X ≦ 0.51 and contains at least a V component as a subcomponent, and its amount is based on the total number of atoms of Bi and Nb. Field of V
Expressed as a ratio [V / (Bi + Nb)] of child numbers , 0 <V /
(Bi + Nb) ≦ 0.02.

[0007] The dielectric ceramic composition of the second invention of the present invention further comprises Cu as a third component in the above-mentioned dielectric ceramic composition, and its amount is based on the total number of atoms of Bi and Nb.
It is characterized by being in the range of 0 <Cu / (Bi + Nb) ≦ 0.01, expressed as a ratio of the number of Cu atoms [Cu / (Bi + Nb)].

[0008]

According to the first aspect of the present invention, the general formula
Is (Bi_TwoO_Three)_X(Nb_TwoO _Five)_1-XMagnet represented by
By adding V (vanadium) to the vessel composition,
It can be fired at high temperature and has a large relative dielectric constant.
Dielectric material with low rate of change and large no-load Q
A porcelain composition can be obtained.

Further, according to the structure of the second aspect of the present invention, low-temperature sintering can be performed by adding Cu (copper),
Further, a dielectric ceramic composition having a larger relative dielectric constant, a smaller rate of change in resonance frequency with temperature, a large unloaded Q, and a more excellent dielectric ceramic composition can be obtained.

[0010]

The present invention will be described more specifically with reference to the following examples.

Example 1 High-purity Bi ₂ O ₃ , Nb ₂ O ₅ , V ₂
The O ₅ was used. These were corrected for purity, weighed in a predetermined amount, and mixed with a ball mill for 17 hours using stabilized zirconia balls and pure water as a solvent. This was suction-filtered to separate most of the water, dried and placed in an alumina crucible and calcined at 700 to 800 ° C for 2 hours. Next, the calcined material was coarsely crushed in an alumina mortar, and further crushed in a ball mill for 17 hours using stabilized zirconia cobblestone with pure water as a solvent,
After suction filtration, most of the water was separated and dried. This is pulverized in an alumina mortar, and a 6 wt% aqueous solution of polyvinyl alcohol as a binder is added thereto in an amount of 6 wt% of the powder amount,
Powdered through a 32 mesh sieve, molding pressure 200kg
/ Cm ² and formed into a column having a diameter of 13 mm and a height of about 5 mm.
The molded product was heated to 600 ° C. in the air and held for 2 hours to burn out the polyvinyl alcohol, and after cooling, transferred to a magnesia porcelain container, covered with a homogeneous lid,
The temperature was raised to a predetermined temperature at 400 ° C./hour, and after holding for 2 hours, the temperature was lowered at 400 ° C./hour.

From the obtained sintered body, the resonance frequency and the no-load Q were obtained from the measurement by the dielectric resonance method, and the relative permittivity was calculated from the dimensions of the sintered body and the resonance frequency. Resonant frequency is 4-5G
Hz. Further, the temperature characteristics of the dielectric ceramic composition in the example of the present invention are upwardly convex as shown in FIG. 1, so that the temperature change rate is the resonance frequency in the temperature range of −25 ° C. to 85 ° C. The temperature was measured and, with reference to 20 ° C., the temperature higher than 20 ° C. was expressed as τfH, and the temperature lower than 20 ° C. was expressed as τfL.

Table 1 shows the composition range and peripheral composition components, firing temperature, firing atmosphere, relative dielectric constant, Q, and temperature change rates τfH and τfL of the resonance frequency of this embodiment. In the table, X represents a coefficient in the general formula. The sample N in the table
o. Those marked with * in the column are comparative examples.

[0014]

[Table 1]

As is clear from Table 1, the sample No. 1 to
5, 7 to 8, 10 to 15 were all within the scope of the first invention of the present invention, so that the firing temperature was 850 ° C. to 1000 ° C.
The specific induction power is 40 or more, the no-load Q value in the microwave region is 500 or more, and the temperature change rate of the resonance frequency is -6.
A dielectric ceramic composition as small as 0 to 70 ppm / ° C. was obtained.

On the other hand, in the comparative example, except for the sample No. 17, the Q value was 500 or less, which was not desirable as a microwave dielectric. When vanadium was not added (Sample No. 17), the firing temperature was 1000 ° C. or more, the specific induction power was 40 or less, the sinterability was extremely poor, and the ceramic was not practical because it was fragile. .

Example 2 Bi ₂ O ₃ , Nb ₂ O ₅ , V ₂ of high purity as starting materials
The dielectric ceramic composition was fired in the same manner as in Example 1 except that CuO was used in addition to O ₅ .

From the obtained sintered body, the resonance frequency and the no-load Q were obtained from the measurement by the dielectric resonance method, and the relative dielectric constant was calculated from the dimensions of the sintered body and the resonance frequency. Resonant frequency is 4-5G
Hz. Further, the temperature characteristics of the dielectric ceramic composition of the present invention in the examples are upwardly convex as shown in FIG. 1, so that the temperature change rate is the resonance frequency in the temperature range of −25 ° C. to 85 ° C. The temperature was measured and, with reference to 20 ° C., the temperature higher than 20 ° C. was expressed as τfH, and the temperature lower than 20 ° C. was expressed as τfL.

Table 2 shows the composition range of this embodiment and the components of the peripheral composition, firing temperature, firing atmosphere, relative dielectric constant, Q, and temperature change rates τfH and τfL of the resonance frequency.

[0020]

[Table 2]

As is clear from Table 2, the sample No. 18 ~
28 were all within the scope of the second invention of the present invention,
It was possible to obtain a dielectric ceramic composition having a no-load Q value in a microwave region of 500 or more and having a small temperature change rate of the resonance frequency.

As described above, according to the first and second embodiments of the present invention, the dielectric ceramic composition of the present invention has a firing temperature of 850 ° C. to 1000 ° C., a relative dielectric constant of 40 or more,
The characteristics that the no-load Q in the microwave region is 500 or more and the temperature change rate of the resonance frequency is −60 to 70 ppm / ° C. are obtained. Further, since firing in nitrogen is possible, it is also possible to obtain a microwave electronic device using Cu as an electrode, which has great industrial value.

[0023]

As described above, according to the structure of the first aspect of the present invention, the general formula is represented by (Bi ₂ O ₃ ) _X (Nb
By adding V to the porcelain composition represented by ₂ O ₅ ) _1-X , it can be fired at a low temperature, has a large relative dielectric constant, a small temperature change rate of a resonance frequency, and has a large unloaded Q property. A dielectric porcelain composition can be obtained.

Further, according to the configuration of the second invention of the present invention,
By adding Cu, low-temperature sintering can be performed, and a dielectric ceramic composition having a larger relative dielectric constant, a smaller rate of change in resonance frequency with temperature, a large unloaded Q, and a more excellent dielectric ceramic composition can be obtained. .

[Brief description of the drawings]

FIG. 1 is a diagram showing a temperature change rate of a resonance frequency of a dielectric ceramic composition in an example of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (56) References MATER. SCI. MONOGR. (1987), 38A (HIGH TECH CERAM., PT.A), P.A. 289-P. 297 (58) Fields investigated (Int. Cl. ⁶ , DB name) H01B 3/12 H01P 7/10 C04B 35/00 CA (STN) EPAT (QUESTEL)

Claims (2)

(57) [Claims] The main component is represented by the general formula (Bi ₂ O ₃ ) _X (Nb ₂
O ₅ ) In the porcelain composition represented by _1-X , X is 0.4
8 ≦ X ≦ 0.51 and as an accessory component,
It contains at least the V component and its amount is the sum of Bi and Nb.
Ratio of the number of V atoms to the number of atoms [V / (Bi + Nb)]
A dielectric ceramic composition characterized by the following formula: 0 <V / (Bi + Nb) ≦ 0.02. 2. The dielectric porcelain composition according to claim 1, further comprising Cu as a sub-component, the amount of which is the total number of atoms of Bi and Nb.
A dielectric ceramic composition characterized by being in the range of 0 <Cu / (Bi + Nb) ≦ 0.01, represented by the ratio of the number of atoms of Cu to [Cu / (Bi + Nb)].