JP2842756B2 - High frequency dielectric ceramic 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 novel high frequency dielectric ceramic composition having a high dielectric constant and a high Q value in a high frequency range such as microwaves and millimeter waves.

[0002]

2. Description of the Related Art In the high frequency region such as microwaves and millimeter waves, dielectric ceramics are widely used for dielectric resonators, MIC dielectric substrates, and the like.

[0003] Conventionally, as this kind of dielectric porcelain,
For example, ZrO ₂ —SnO ₂ —TiO ₂ based material, BaO—
TiO ₂ materials, (Ba, Sr) (Zr, Ti) O ₃ based materials, Ba (Zn, Ta) O ₃ based materials and the like are known.

[0004] The above materials have a frequency of 10 with various improvements.
At GHz, the dielectric constant is 20 to 40, the Q value is 3000 or more, and the temperature coefficient (τf) of the resonance frequency is 0 ppm /
Excellent properties around ° C have been achieved.

[0005]

Recently, there has been a tendency to use higher frequencies and dielectric materials have been required to have more excellent dielectric properties, particularly to improve the Q value. However, in the conventional dielectric material described above,
At 10 GHz, even if the Q value is particularly increased, the limit is about 6000, and at present, it is impossible to sufficiently meet these requirements. Further, the temperature coefficient (τf) of the resonance frequency cannot be controlled with the conventional dielectric material.

An object of the present invention is to provide a dielectric ceramic composition which can meet such a demand, has a high dielectric constant and a high Q value in a high frequency range, and can control the temperature characteristics of a resonance frequency. It is assumed that.

[0007]

Means for Solving the Problems The present inventors have studied the above problems and found that BaO, MgO, WO
_3. It has been found that excellent dielectric properties can be obtained by containing Ta ₂ O ₅ and adjusting them to a specific composition.

That is, the dielectric porcelain composition of the present invention comprises a metal composite oxide, and is composed of BaO, MgO, WO ₃ and Ta _2.
It is composed of O ₅ . In the present invention, the composition formula based on the molar ratio is expressed as xBaO.yMgO.zWO ₃ .w
When expressed as TaO _5/2 , the x, y, z, w are

[0009]

(Equation 2)

The composition range is set so as to satisfy the following.

The reason why these ratios are set in the above range is that if the BaO content (x) is less than 0.40, the Q value decreases and sintering becomes difficult, and if it exceeds 0.55, the Q value decreases. Because. On the other hand, if the amount of MgO (y) is less than 0.10, sinterability becomes difficult or the Q value decreases, and if it is more than 0.40, the Q value tends to decrease. Further, when the WO ₃ amount (z) is more than 0.30, the Q value decreases. Further, when the amount (w) of TaO _5/2 is 0.40 or more, the Q value decreases.

And, in the dielectric ceramic composition of the present invention,
By changing the molar ratio of Ta ₂ O ₅ , BaO, MgO, and WO ₃ within the above range, the temperature characteristics of the resonance frequency can be freely controlled in a certain region while maintaining a high Q value.

Furthermore, the reason for setting 0.20 ≦ z + w ≦ 0.40 is that if z + w is smaller than 0.2 or larger than 0.4, the Q value is reduced or sintering is poor. is there.

Also,

[0015]

(Equation 3)

The reason is that when the value is less than 0.17 or 0.94 or more, the Q value is reduced or sintering is poor.

Further, with respect to 1 mol part of the composition, Y, H
f, Zr, Mn, Sn, Ti, Ca, La, Ce, N
By adding and containing at least one oxide of d, Pr, and Sm in a range of 0.3 mol part or less, sinterability can be improved and dielectric properties can be controlled.

As a method for producing a porcelain based on the present invention, for example, an oxide of Ba, Mg, W or Ta or a metal salt such as a carbonate or a nitrate which forms an oxide upon firing is used as a raw material, After weighing so as to be within the specified range, mix well. Then, the mixture is 900-1
It is calcined at 300 ° C and pulverized. Then, the calcined powder is formed into a predetermined shape by a forming method such as press forming or a doctor blade method.

Then, the molded body is fired at 1300 to 1600 ° C. in an oxidizing atmosphere such as the air to obtain a dielectric ceramic.

[0020]

In the dielectric ceramic composition of the present invention, BaO, Mg
By changing the molar ratio of O, WO ₃ , and Ta ₂ O ₅ , the temperature characteristic of the resonance frequency can be freely controlled in a constant region while maintaining a high Q value. That is, by increasing the Ta amount, the temperature coefficient τf tends to increase, and the temperature coefficient (τf) can be controlled. Hereinafter, the present invention will be described with reference to the following examples.

[0021]

【Example】

Example 1 As raw materials, BaCO ₃ , MgCO ₃ ,
Using WO ₃ and Ta ₂ O ₅ powders,
The mixture was weighed to the ratio shown in Table 1 and put into a ball mill lined with rubber together with water and wet-mixed for 8 hours. Next, after dehydrating and drying the mixture, it was calcined at 1000 ° C. for 2 hours, and the calcined product was wet-pulverized for 8 hours by putting water and an organic binder into a ball mill.

Thereafter, the pulverized material was dried, and then granulated through a No. 50 mesh net.
It was formed into a cylinder having a size of 10 mmφ × 5 mmt under a pressure of kg / cm ² . Furthermore, this column is
It was fired under the condition of 00 ° C. × 6 hours to obtain a porcelain sample.

With respect to the porcelain sample thus obtained, the relative dielectric constant (εr) and Q value at a frequency of 10 GHz were measured by the dielectric resonator method, and the temperature change of the resonance frequency in the temperature range from 25 ° C. to 85 ° C. The temperature coefficient (τf) of the resonance frequency was calculated from the ratio. The results are shown in Table 1.

[0024]

[Table 1]

According to Table 1, BaO, MgO, WO ₃ ,
Sample N in which the composition of Ta ₂ O _{5 is out} of the range of the present invention
o. 4,8,11,12,18,22,25,26,2
In Nos. 7 and 28, the Q value was 1200 or less or poor sintering occurred. In contrast, the sample of the present invention has a relative dielectric constant of 10 or more,
When the Q value of 3000 or more is achieved and the amount of Ta ₂ O ₅ is changed, the temperature characteristic of the resonance frequency becomes −28 to 13 ppm.
/ ° C.

Example 2 As raw materials, BaCO ₃ , MgCO ₃ ,
Using WO ₃ and Ta ₂ O ₅ powder, the materials No. 2 and
The compositions of Nos. 7 and 10 were weighed, and Y ₂ O ₃ , HfO ₂ , ZrO ₂ , MnO ₂ , and Sn were added to 1 mol part of the main component composition.
O ₂ , TiO ₂ , CaO, La ₂ O ₃ , CeO ₂ , Nd
_At least one type of powder of ₂ O ₃ , Pr ₆ O ₁₁ , and Sm ₂ O ₃ was weighed in the proportions shown in Table 2, and this was put together with water in a rubber-lined ball mill and wet-mixed for 8 hours. Next, after dehydrating and drying this mixture, it was calcined at 1000 ° C. for 2 hours, and the calcined product was put into a ball mill with water and an organic binder and wet-ground for 8 hours.

Thereafter, the pulverized product was dried, and then granulated through a No. 50 mesh net.
It was formed into a cylinder having a size of 10 mmφ × 5 mmt under a pressure of kg / cm ² . Furthermore, this column is
It was fired under the condition of 00 ° C. × 6 hours to obtain a porcelain sample.

With respect to the porcelain sample thus obtained, the relative dielectric constant (εr) and Q value at a frequency of 10 GHz were measured by a dielectric resonator method, and the temperature change of the resonance frequency in a temperature range from 25 ° C. to 85 ° C. The temperature coefficient (τf) of the resonance frequency was calculated from the ratio. Table 2 shows the results.

[0029]

[Table 2]

According to Table 2, Y, Hf,
Zr, Mn, Sn, Ti, Ca, La, Ce, Nd, P
Even when at least one of the oxides of r and Sm is added and contained in an amount of 0.2 mol part or less, a high Q value of 3000 or more is obtained, and the temperature characteristic of the resonance frequency is also ± 30 ppm / ° C.
It can be seen that it can be controlled to any value within the range.

[0031]

As described in detail above, according to the present invention, B
By mixing aO, MgO, WO ₃ and Ta ₂ O ₅ at a predetermined ratio, a high dielectric constant and a high Q value can be obtained in a high frequency region, and a temperature characteristic can be controlled in a constant region by controlling the amount of Ta. It can be controlled freely. Thereby, it can be sufficiently applied to various resonator materials and MIC dielectric substrate materials used in microwave and millimeter wave regions.

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-18806 (JP, A)

Claims (1)

(57) [Claims] 1. A composition containing BaO, MgO, WO ₃ and Ta ₂ O ₅ , and having a molar ratio of xBaO.yMgO.z
When expressed as WO ₃ · wTaO _5/2 , the above x, y, z, w
Is A dielectric ceramic composition for high frequencies, characterized by satisfying the following.