JP2001097770A - Dielectric porcelain composition for high-frequency and dielectric resonator using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dielectric porcelain composition which has an εr of about 16 to 24 and a high Q value and is small in the lowering rate of a Q value at 125 deg.C to that at 25 deg.C and in which the curve (temperature drift) of the temperature coefficient τf of resonance frequency in a range of 25 to 85 deg.C can be controlled to a range of 0 ±3 (ppm/ deg.C), and to provide a dielectric resonator. SOLUTION: This dielectric porcelain composition comprises 100 pts.wt. of a main component, 0.1 to 3.5 pts.wt. of at least one of WO3, Al2O3 and CeO2, and <3.0 pts.wt. of Al2O3. The main component contains at least Mg, Ca, and Ti as metal elements, and satisfies 0.42<=(a)<=0.51, 0.01<=(b)<=0.06, and 0.45<=(c)<=0.53 [provided that (a)+(b)+(c)=1], when the molar ratio composition formula of the metal elements is represented by: aMgO.bCaO.cTiO2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency dielectric ceramic composition and a dielectric resonator having a high Q value in a high frequency region such as a microwave and a millimeter wave. High-frequency dielectric materials that can be used for various resonator materials, MIC dielectric substrate materials, dielectric waveguide materials, multilayer ceramic capacitors, and impedance matching of various microwave circuits used in high-frequency regions such as waves The present invention relates to a body porcelain composition and a dielectric resonator.

[0002]

2. Description of the Related Art Dielectric ceramics are widely used in dielectric resonators, MIC dielectric substrates, waveguides, and the like in high-frequency regions such as microwaves and millimeter waves. The required characteristics are (1) since the wavelength is reduced to 1 / εr ^1/2 in the dielectric, the relative dielectric constant is large for the demand for miniaturization, and (2) the dielectric loss at high frequencies Are small, that is, a high Q value, and (3) the change in resonance frequency with respect to temperature is small and stable. Conventionally, as this type of dielectric porcelain, for example, Japanese Unexamined Patent Publication No.
x) MgTiO ₃ · xCaTiO ₃ system material (however, 0.
03 ≦ x ≦ 0.07).
8 No. _{(1-x) MgTiO 3 ·} xCaTiO 3 + C
An o ₂ O ₃ -based material (provided that 0.93 ≦ x ≦ 0.95) is shown, and JP-A-6-199567 discloses (1-x) MgT
iO ₃ xCaTiO ₃ + Al ₂ O ₃ material (however, 0.9
3 ≦ x ≦ 0.95) is shown.

[0003]

However, these prior art dielectric ceramics have a curved temperature coefficient τf of the resonance frequency, that is, the linearity of the temperature drift is low. Further, the Q value at a high temperature (for example, 125 ° C.) is significantly lower than the Q value at a normal temperature (for example, 25 ° C.). For this reason, it is difficult for a dielectric resonator or a dielectric substrate using these dielectric porcelains to accurately control a characteristic change due to a temperature change, and the loss at a high frequency becomes large. Was. The present invention has been completed in view of the above circumstances. While maintaining a high Q value at εr of about 16 to 24, the resonance coefficient has a temperature coefficient τf bend, that is, the linearity of the temperature drift is high, and at room temperature. It is an object of the present invention to provide a high-frequency dielectric ceramic composition and a dielectric resonator in which the rate of decrease in the Q value at a high temperature with respect to the Q value is small.

[0004]

The dielectric porcelain composition of the present invention comprises a composite oxide containing at least Mg, Ca, and Ti as metal elements, and has a composition formula of aMgO.bCaO based on a molar ratio of the metal elements. When expressed as cTiO ₂ , a, b, and c satisfy 0.42 ≦ a ≦ 0.51 0.01 ≦ b ≦ 0.06 0.45 ≦ c ≦ 0.53, where a + b + c = 1 is satisfied. W, A to 100 parts by weight of the main component composition
l and Ce are at least one of WO ₃ and Al ₂
It is characterized in that it contains 0.01 to 3.5 parts by weight in terms of O ₃ and CeO ₂ , and the content of Al is less than 3.0 parts by weight in terms of Al ₂ O ₃ .

[0005] Further, in the above dielectric ceramic composition,
Q value at 125 ° C. is 75% of Q value at 25 ° C.
The above is the feature.

Further, in the dielectric resonator according to the present invention, a dielectric porcelain is arranged between a pair of input / output terminals, wherein the dielectric porcelain operates by electromagnetic field coupling. It is composed of a body porcelain composition.

According to the high frequency dielectric ceramic composition of the present invention,
By including at least one of W, Al, and Ce as the main component, it has a high Q value and exhibits a bending (temperature drift) of the temperature coefficient τf of the resonance frequency of 25 to
Control at 85 ° C. within the range of 0 ± 3 (ppm / ° C.), that is, it is possible to increase the linearity of the temperature drift. In addition, it is possible to reduce the rate of decrease in the Q value at a high temperature with respect to the Q value at a normal temperature.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a composite oxide containing at least Mg, Ca, and Ti as metal elements, and a composition formula based on a molar ratio of the metal elements is aM
When expressed as gO · bCaO · cTiO ₂ , the a, b
And c are 0.42 ≦ a ≦ 0.51 0.01 ≦ b ≦ 0.06 0.45 ≦ c ≦ 0.53 where a + b + c = 1 with respect to 100 parts by weight of the main component composition. W, A
l and Ce are at least one of WO ₃ and Al ₂
It is important to contain 0.01 to 3.5 parts by weight in terms of O ₃ and CeO _2, and to contain Al less than 3.0 parts by weight in terms of Al ₂ O ₃ . These a, b, c and WO ₃ , A
The reasons for limiting the contents of l ₂ O ₃ and CeO ₂ to the above ranges are as follows.

That is, 0.42 ≦ a ≦ 0.51 means that when 0.51 <a, the Q value decreases or τf becomes negative and the absolute value of τf exceeds 50. Because. When a <0.42, the Q value decreases, τf increases positively, the absolute value of τf greatly exceeds 50, the temperature coefficient τf of the resonance frequency bends greatly, and the linearity of the temperature drift decreases. It is because it is lowered. In particular, 0.43 <a <0.49 is desirable.

The reason for setting 0.01 ≦ b ≦ 0.06 is that when 0.06 <b, the temperature coefficient τf of the resonance frequency becomes positive, the absolute value of τf greatly exceeds 50, and Q
When b <0.01, τf becomes negative, the absolute value of τf exceeds 50, and the bending of the temperature coefficient τf of the resonance frequency increases, and the linearity of the temperature drift decreases. Because they do. In particular, 0.02
≦ b ≦ 0.05 is preferred.

Further, the reason that 0.45 ≦ c ≦ 0.53 is satisfied is that when 0.53 <c, the temperature coefficient τ
This is because f becomes positive and the absolute value of τf greatly exceeds 50, and the bending of the temperature coefficient τf of the resonance frequency increases, and the linearity of the temperature drift decreases. c <
This is because in the case of 0.45, the Q value decreases and the relative dielectric constant decreases. In particular, the range of 0.46 ≦ c ≦ 51 is preferable.

In addition, at least one of W, Al and Ce is not less than 0.1 in terms of WO ₃ , Al ₂ O ₃ and CeO ₂ .
The reason for containing 0.1 to 3.5 parts by weight is that when the amount is less than 0.1 part by weight, the linearity of the temperature drift is low.
This is because when the amount is more than the weight part, the decrease rate of the Q value at a high temperature (125 ° C.) is large.

[0012] Incidentally, the content of Al in terms of Al ₂ O ₃ 3.
The reason why the content is less than 0 parts by weight is that when the content is 3.0 parts by weight or more, the reduction rate of the Q value at a high temperature (125 ° C.) is large.

Incidentally, in the present invention, the Q value is a Q value generally established in a microwave dielectric × a measurement frequency f =
It shows a value converted to a Qf value at 1 GHz from a certain relationship.

Thus, the dielectric ceramic composition of the present invention comprises:
A high dielectric constant of about 16 to 24, a high Q value, a high temperature drift linearity, and a small reduction rate of the Q value at a high temperature (125 ° C) with respect to the Q value at a normal temperature (25 ° C). Having.

The high frequency dielectric ceramic composition of the present invention is produced, for example, as follows. As a starting material,
Using each powder of magnesium carbonate, calcium carbonate and titanium oxide, after weighing to the desired ratio described above, pure water is added, and the mixed raw material has an average particle size of 2.0 μm or less for 10 to 30 hours. And wet milling / pulverization with a mill using zirconia balls or the like.

After the mixture has been dried,
Calcination treatment is performed at a temperature of 2 to 10 hours. Tungsten oxide, aluminum oxide and cerium oxide are added to the obtained calcined product in the specific range described above, and the mixture is pulverized. Further, a predetermined amount, for example, about 5% by weight of an organic binder for molding is added, and the resulting powder is sized. The obtained powder is optionally molded by a desired molding means, for example, a die press, a cold isostatic press, an extrusion molding or the like. After being formed into a shape, a binder removal treatment is performed in an oxidizing atmosphere such as air at a temperature of 600 ° C. or more and a holding time of 10 hours or more.
By firing in the air at a temperature of 1400 ° C. for 1 to 10 hours, a dielectric porcelain can be obtained.

As a starting material of the dielectric ceramic composition of the present invention, in addition to oxides, oxides such as carbonates, acetates, nitrates, carbonates, hydroxides and the like can be obtained by heat treatment in an oxidizing atmosphere. A compound that can be produced may be used. Further, for Mg, Ca and Ti, MgTiO ₃ , CaTiO ₃ prepared by a sol-gel method or a hydrothermal method, etc.
May be used.

In the present invention, Zr, Si, Ba and the like may be mixed as unavoidable impurities in the porcelain. However, if these are mixed in 0.4% by weight or less in terms of oxide, there is no problem in characteristics. .

The dielectric ceramic composition of the present invention is most useful for a dielectric resonator. FIG. 1 shows a schematic diagram of a TE mode dielectric resonator as the dielectric resonator of the present invention. The resonator shown in FIG. 1 is formed by forming an input terminal 2 and an output terminal 3 on both sides of a metal case 1 and arranging a dielectric ceramic 4 having the above-described composition between these terminals 2 and 3. You. As described above, in the TE mode type dielectric resonator, the microwave is input from the input terminal 2, and the microwave is confined in the dielectric ceramic 4 by the reflection of the boundary between the dielectric ceramic 4 and the free space, and is specified. Resonance occurs at the frequency of

This signal is electromagnetically coupled to the output terminal 3 and output. Although not shown, the dielectric ceramic composition of the present invention may be applied to a coaxial resonator, a strip line resonator, a TM mode dielectric ceramic resonator, and other resonators using a TEM mode. Of course.

[0021]

EXAMPLES Using high-purity magnesium carbonate (MgCO ₃ ), calcium carbonate (CaCO ₃ ), and titanium oxide (TiO ₂ ) powders as starting materials, they were listed in Table 1.
After weighing so that the molar ratio of the mixture becomes, pure water was added, and wet mixing and grinding were performed for about 20 hours by a mill using ZrO ₂ balls until the average particle size of the mixed raw material became 2.0 μm or less.

After drying this mixture, it was calcined at 1200 ° C. for 2 hours. High purity tungsten oxide (WO ₃ ), aluminum oxide (Al ₂ O ₃ ), and cerium oxide (CeO ₂ ) were added to the obtained calcined product so as to have the ratio shown in Table 1, and the average particle size of the mixed raw material was adjusted. Until it becomes 2.0 μm or less
Wet mixing and grinding were performed for about 20 hours by a mill using ZrO ₂ balls. After drying the slurry, 5 wt% of a binder was further added, and the resulting granules were sized. The obtained powder was formed into a disk at a pressure of about 1 ton / cm ² . The obtained molded body was removed from the atmosphere in the atmosphere at a debailing temperature of 800 ° C. for a holding time of 1 hour.
The binder removal process is performed under the condition of 0 hour, and
Calcination was performed in the air at a temperature of 0 to 1400 ° C. for 4 hours.

The obtained porcelain is polished flat, ultrasonically cleaned in acetone, dried at 150 ° C. for 1 hour, and then room temperature at 25 ° C.
At a measurement frequency of 8 to 10 GH by a cylindrical resonator method.
The relative dielectric constant εr and Q value were measured at z. Qf is a Q value generally established in a microwave dielectric × a measurement frequency f =
It was converted to a Qf value at 1 GHz from a certain relationship. Further, the Q value at a high temperature of 125 ° C. was measured in the same manner, and the retention of the Q value at 125 ° C. with respect to the Q value at 25 ° C. was calculated.

The temperature coefficient τf of the resonance frequency is 25 to 85
It was measured in the range of ° C. Τf at 25 to 55 ° C.
The value obtained by subtracting τf of 55 to 85 ° C from the above was defined as τf bending (temperature drift).

[0025]

[Table 1]

As is clear from Table 1, the dielectric ceramic composition outside the range of the present invention has a low Q value or τf.
Is greater than 50, or the bend (temperature drift) of τf exceeds 0 ± 3 ppm / ° C.

In contrast, the dielectric ceramic composition of the present invention has a relative dielectric constant of 20 to 23 and a Q value of 80,000 (1 G
Hz), τf is within ± 50 (ppm / ° C.), and the bending (temperature drift) of τf is 0 ± 3 (ppm / ° C).
℃), the Q value of 125 ° C against the Q value of 25 ° C is 75
%, Which indicates that excellent dielectric properties can be obtained.

[0028]

As described in detail above, the composition is composed of a composite oxide containing at least Mg, Ca, and Ti as the metal elements, and the composition formula based on the molar ratio of the metal elements is aMgO.
When expressed as bCaO · cTiO ₂ , the a, b and c are 0.42 ≦ a ≦ 0.51, 0.01 ≦ b ≦ 0.
06, 0.45 ≦ c ≦ 0.53 (where a + b + c =
For 100 parts by weight of the main component composition satisfying 1),
At least one of W, Al and Ce
It has a high Q value because it contains 0.01 to 3.5 parts by weight in terms of O ₃ , Al ₂ O ₃ and CeO ₂ , and less than 3.0 parts by weight of Al in terms of Al ₂ O _3. , The decrease rate of the Q value at 125 ° C. with respect to 25 ° C. is small, and
In the range of 5 ° C., the bending (temperature drift) of the temperature coefficient τf of the resonance frequency can be controlled in the range of 0 ± 3 (ppm / ° C.).

Thus, the high frequency dielectric ceramic composition of the present invention can be used for, for example, automobile telephones, cordless telephones,
In devices such as personal radios and satellite broadcast receivers,
Resonator materials used in microwave and millimeter wave regions, dielectric substrate materials for MICs, dielectric waveguides, dielectric antennas, impedance matching of various microwave circuits,
It is applied to various other electronic components and the like, and is particularly suitable for a dielectric resonator.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a dielectric resonator of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Metal case 2 ... Input terminal 3 ... Output terminal 4 ... Dielectric porcelain

Claims (3)

[Claims] 1. At least Mg, Ca, T as a metal element
When a composition formula based on the molar ratio of the metal element is represented by aMgO · bCaO · cTiO ₂ , a, b, and c are 0.42 ≦ a ≦ 0.510. 01 ≦ b ≦ 0.06 0.45 ≦ c ≦ 0.53 where W and A are relative to 100 parts by weight of the main component composition satisfying a + b + c = 1.
l and Ce are at least one of WO ₃ and Al ₂
A dielectric ceramic composition for high frequency use, comprising 0.01 to 3.5 parts by weight in terms of O ₃ and CeO ₂ , and having an Al content of less than 3.0 parts by weight in terms of Al ₂ O ₃ . . 2. The high frequency dielectric ceramic composition according to claim 1, wherein the Q value at 125 ° C. is 75% or more of the Q value at 25 ° C. 3. A high frequency dielectric ceramic composition according to claim 1 is disposed between a pair of input / output terminals to operate by electromagnetic field coupling. Dielectric resonator.