JP3393775B2 - Dielectric ceramic composition and dielectric resonator - 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 example, a circuit element substrate and a dielectric resonator support member used in microwave and millimeter wave bands such as microwave and millimeter wave integrated circuits. , Dielectric resonator, dielectric waveguide,
The present invention relates to a high-frequency dielectric ceramic composition useful as a material for a dielectric antenna and the like, and a dielectric resonator in which the dielectric ceramic is fixed to a substrate via a supporting member.

[0002]

2. Description of the Related Art A high frequency circuit element such as a microwave or millimeter wave integrated circuit may employ a structure in which a dielectric ceramic is fixed to a substrate through a supporting member. For example,
As shown in FIG. 1, the dielectric resonator control type microwave oscillator mounts the dielectric porcelain 1 on the porcelain substrate 3 via the support member 2 and utilizes the magnetic field H leaking to the outside of the dielectric porcelain 1. It is connected to the strip line 4 provided on the porcelain substrate 3, and is housed in the metal case 5.

In this type of high frequency circuit, by controlling the leakage of the electromagnetic field of the dielectric porcelain 1 through the support member 2, a resonance system with a high no-load Q is constructed, so that it is supported. The member has a low relative permittivity and a dielectric loss (t
It is necessary to use a material having a small an δ) (having a large Q value). Therefore, conventionally, as the material of the supporting member, the relative dielectric constant is about 7, and the Q value at the measurement frequency of 10 GHz is about 150.
00 forsterite is used, and the material of the porcelain substrate is mainly a dielectric constant of about 10 and a measurement frequency of 1
Alumina porcelain having a Q value at 0 GHz of 20000 or more has been adopted (see, for example, JP-A-62-103904).

On the other hand, cordierite is conventionally known as a material having a low relative dielectric constant. However, since a firing temperature range is extremely narrow, it is difficult to obtain a dense sintered body. It was used as a glass ceramic having a relative dielectric constant of 4 to 6 and a Q value of about 1000 at a measurement frequency of 10 GHz (see, for example, JP-A-61-23).
4128, etc.).

[0005]

However, the relative permittivities of conventionally used alumina and forsterite are about 10 and about 7, respectively, and with the recent widespread use of high frequency dielectric resonators. , Lower dielectric constant materials have been sought.

On the other hand, porcelain such as glass ceramics used as a low dielectric constant material has a small relative dielectric constant of about 4 to 6, but has a Q value of about 1000 at 10 GHz. Along with the widespread use of resonators, there has been a demand for a low dielectric constant material having a higher Q value.

Alumina porcelain, which is mainly used for the porcelain substrate of the resonator, has a relatively high relative permittivity of about 10, and the line width becomes too small when forming a high impedance stripline (usually (1 μm or less), there is a problem that disconnection occurs or relative line width variation increases, and the defect rate of the microwave integrated circuit increases.

On the other hand, the impedance of the strip line in this type of porcelain substrate is inversely proportional to the relative permittivity and the width of the strip line if the substrate thickness is constant. Therefore, instead of reducing the line width, Impedance can also be increased by using a substrate material having a low relative dielectric constant, and therefore, a lower dielectric constant material has been required.

As a means for solving the above problems, the present applicant has proposed a complex oxide composed of Mg, Al, and Si as metal elements, the molar ratio composition formula of which is an oxide of each metal element is xMgO.yAl ₂ O. _When expressed as ₃ · zSiO ₂ , the above x, y and z are 10 ≦ x ≦ 40, 10 ≦ y ≦ 40, 20.
≦ z ≦ 80, x + y + z = 100 are satisfied, the relative dielectric constant is 7 or less, and the Q value at the measurement frequency of 10 GHz is 200.
A dielectric ceramic composition for high frequency of 0 or more and a dielectric resonator have already been proposed (Japanese Patent Application No. 7-195211).
issue).

This high frequency dielectric ceramic composition was excellent in that it had a lower relative permittivity than alumina and forsterite and a higher Q value than glass ceramics.

However, conventionally, since cordierite has an extremely narrow firing temperature range, it is difficult to obtain a dense sintered body, and the high frequency dielectric ceramic composition previously filed by the applicant was no exception.

The present invention has a low dielectric constant and a measurement frequency of 1
An object of the present invention is to provide a dielectric ceramic composition and a dielectric resonator that have a high Q value at 0 GHz (room temperature) and that can improve firing conditions.

[0013]

The dielectric porcelain composition of the present invention is a composite oxide composed of Mg, Al and Si as metal elements, and the composition formula based on the molar ratio of each metal element oxide is xMgO. When expressed as yAl ₂ O ₃ · zSiO ₂ ,
The above x, y and z are 10 ≦ x ≦ 40 and 10 ≦ y ≦ 4.
0 to 20 ≦ z ≦ 80, consisting of 60 to 99.9% by weight of main components satisfying x + y + z = 100 and 0.1 to 40% by weight of Ce in terms of CeO ₂ , and measured with a relative dielectric constant of 7 or less. The Q value at a frequency of 10 GHz (room temperature) is 3000 or more, and it is used for high frequency. In addition, 60 to 99.9% by weight of the main component and Ti as TiO
Consists of 0.1 to 40% by weight in terms of ₂ , 1250-1
Firing at 450 ℃, dielectric constant 7 or less, measurement frequency 1
It is characterized in that the Q value at 0 GHz (room temperature) is 3000 or more.

The dielectric resonator of the present invention is a dielectric resonator in which a dielectric ceramic is fixed on a substrate through a supporting member, wherein the substrate and / or the supporting member is the above-mentioned dielectric ceramic composition. It consists of

[0015]

In the dielectric porcelain composition of the present invention, the firing conditions such as the firing temperature are strictly controlled by containing Ti or Ce in the specified amounts in terms of TiO ₂ or CeO ₂ with respect to the above main components. The firing conditions can be improved without significantly deteriorating the characteristics obtained in this way.

That is, the relative dielectric constant is 4 to 7, and the measurement frequency is 10
It is possible to obtain a dielectric ceramic with a low dielectric constant having a Q value of 3000 or more at GHz, and for example, a firing temperature range of 1
It is possible to improve the temperature from about 0 ° C. to about 100 ° C., facilitate the manufacturing, and improve the mass productivity.

Further, by using such a dielectric ceramic having a low dielectric constant and a high Q value for a supporting member and / or a substrate of a dielectric resonator, for example, a high impedance microwave integrated circuit for high frequencies and the like can be obtained. The circuit element for use can be manufactured without impairing reliability.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION In the dielectric ceramic composition of the present invention, when the composition formula of the molar ratio is represented by xMgO.yAl ₂ O ₃ .zSiO ₂ , x, y and z are 10 ≦ x ≦ 40, 10 ≦ y
The main component is one that satisfies ≦ 40, 20 ≦ z ≦ 80, and x + y + z = 100.

The reason why the component composition of the dielectric ceramic composition of the present invention is limited to the above range is as follows. That is, M
The reason that x, which represents the mole percentage of gO, is 10 to 40 mol% is that if it is less than 10 mol%, a good sintered body cannot be obtained and the Q value is low, and if it exceeds 40 mol%, the relative dielectric constant becomes high. Is. In particular, x, which indicates the amount of MgO, is preferably 15 to 35 mol% from the viewpoint of setting the Q value to 5000 or more.

Further, y, which indicates the molar percentage of Al ₂ O ₃ , is set to 10 to 40 mol%, because a good sintered body can be obtained when the amount of Al ₂ O ₃ y is smaller than 10 mol%. This is because the Q value becomes low and the relative dielectric constant becomes high when it exceeds 40 mol%. Y showing the amount of Al ₂ O ₃ has a Q value of 5
From the viewpoint of being 000 or more, 15 to 35 mol% is desirable.

The molar percentage z of SiO ₂ is 20 ≦ z ≦ 80.
The mol ratio is set so that when z is less than 20 mol%, the relative dielectric constant becomes large, and when it exceeds 80 mol%, a good sintered body cannot be obtained and the Q value becomes low. Z showing the amount of SiO ₂
Is preferably 30 to 65 mol% from the viewpoint that the Q value is 5000 or more.

According to the present invention, T
The content of i or Ce was 0.1 to 40% by weight in terms of TiO ₂ or CeO ₂ , respectively, when the content of TiO ₂ or CeO ₂ was less than 0.1% by weight (the main component was 99.9% by weight). %, The densification firing temperature does not increase, and if it exceeds 40% by weight (main component is 60%).
This is because the firing temperature range rather narrows when it is less than wt%. Higher becomes densification sintering temperature is large to increase the content of TiO ₂ or CeO _2, whereas since the dielectric constant is increased, in consideration of these characteristics and densification sintering temperature, the content of TiO ₂ or CeO ₂ It is desirable to determine the amount, but in particular 0.1 to 20% by weight is desirable.

The dielectric ceramic composition of the present invention has a Q value of 50.
15 ≦ x ≦ 35, 15 ≦ y ≦ 3 in order to be 00 or more
It is desirable to satisfy 5, 30 ≦ z ≦ 65. In the present invention, in particular, the composition of cordierite, ie x = 22.
2, y = 22.2, z = 55.6, TiO ₂ or Ce
It is desirable to contain O _{2 in an amount} of 0.1 to 40% by weight.

Q value of 3000 at a measurement frequency of 10 GHz
The reason for satisfying the above is that when the Q value is 3,000 or more, it is possible to sufficiently cope with a recent high frequency band dielectric resonator. The higher the Q value, the more desirable, but especially the measurement frequency is 10 GHz.
It is desirable that the Q value at is 5000 or more.

In the dielectric porcelain composition of the present invention, the main crystal phase is cordierite, and other crystal phases include mullite, spinel, protoenstatite, clinoenstatite, cristobalite, forsterite, tridymite and safarin. In some cases, CeO ₂ or Ce ₂ Si ₂ O ₇ may be precipitated.
When Ti is Ti, MgTiO ₃ , Mg ₂ Al ₆ T
i ₇ O ₂₅ etc. may precipitate, but the precipitation phase differs depending on the composition.

Further, the dielectric resonator of the present invention, as shown in FIG. 1, has the dielectric ceramic 1 on the substrate 3 via the supporting member 2.
Are fixed, and the supporting member 2 or the substrate 3, or the supporting member 2 and the substrate 3 are made of the above dielectric ceramic composition. In this case, a well-known material is used as the dielectric ceramic 1. The dielectric ceramic composition of the present invention may be used as the dielectric ceramic 1.

The dielectric porcelain of the present invention, as a raw material powder,
For example, MgCO ₃ powder, Al ₂ O ₃ powder, SiO ₂ powder, CeO ₂ powder or TiO ₂ powder is used, weighed at a predetermined ratio, wet-mixed and dried, and this mixture is dried at 1100-1300 ° C. in the atmosphere. After calcination in, it was crushed. It can be obtained by adding an appropriate amount of a binder to the obtained powder to form a compact, and firing the compact at 1250 to 1450 ° C. in the atmosphere.

The dielectric ceramic composition of the present invention is composed of Mg, Al, Si, Ti or Ce as a metal element. For example, Ca is used as a ball component of a crushed ball or an impurity of raw material powder. , Ba, Zr, Ni, Fe,
Although Cr, P, Na, etc. may be mixed in, a porcelain having a low dielectric constant and a high Q value can be obtained also in this case as long as the above composition is satisfied.

In the dielectric ceramic composition of the present invention, if a low dielectric constant and a high Q value are required, for example, a circuit element substrate, a dielectric resonator dielectric ceramic, or a dielectric waveguide. , A dielectric antenna, etc. can be applied, but as described above, it is most suitable for a supporting member or a substrate of a dielectric resonator.

[0030]

【Example】

Example 1 MgCO _{3 having} a purity of 99% as a raw material powder, a purity of 99.7
% Al ₂ O ₃ , 99.4% pure SiO ₂ powder, and 99.9% pure CeO ₂ were used.
The composition was weighed so as to have the composition shown in Examples ₂ and 3, wet-mixed for 15 hours by a ball mill using ZrO ₂ balls, dried and calcined at 1200 ° C. for 2 hours, and then pulverized. Granulate by adding an appropriate amount of binder to the obtained powder,
This was molded under a pressure of 1000 kg / cm ² to obtain a molded product having a diameter of 12 mm and a thickness of 8 mm. This molded body was fired in the atmosphere at the temperatures shown in Tables 1, 2, and 3 for 2 hours to give a diameter of about 10
A dielectric ceramic sample having a thickness of 5 mm and a thickness of about 5 mm was obtained.

Using this sample, the dielectric constant and the Q value at a frequency of 10 GHz (room temperature) were measured by the dielectric cylinder resonator method, and the results are shown in Tables 1, 2 and 3.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

[Table 3]

According to these Tables 1, 2, and 3, the dielectric ceramic composition according to the present invention has a low relative permittivity of 7 or less and a high Q value of 3000 or more at a measurement frequency of 10 GHz. You can see that. Further, it can be seen that the baking temperature range can be expanded from 10 ° C to 80 ° C.

Incidentally, in FIG. The X-ray-diffraction chart figure of 59 is shown. From FIG. 2, in addition to cordierite,
It can be seen that CeO ₂ is precipitated.

Example 2 Instead of the CeO ₂ powder of Example 1, T having a purity of 99.0% was used.
A dielectric ceramic sample was prepared and evaluated in the same manner as in Example 1 except that the iO ₂ powder was used. The results are shown in Table 4.

[0038]

[Table 4]

From Table 4, the dielectric ceramic composition according to the present invention has a low relative permittivity of 6 or less, and a measurement frequency of 1
It can be seen that the Q value at 0 GHz is as high as 3000 or more. Further, it can be seen that the baking temperature range can be expanded from 10 ° C to 120 ° C.

The sample No. is shown in FIG. The X-ray-diffraction chart figure of 105 is shown. It can be seen from FIG. 2 that MgTiO ₃ is precipitated in addition to cordierite.

[0041]

The dielectric porcelain composition of the present invention has a low relative dielectric constant of 7 or less and a Q value of 3000 at 10 GHz.
It is possible to obtain a porcelain having a high Q value as described above. For example, it is possible to improve a firing temperature range of about 10 ° C. to about 100 ° C., facilitate manufacturing, and improve mass productivity.

By using this dielectric ceramic composition as a supporting member or substrate of a dielectric resonator, a high-frequency circuit element such as a high-impedance microwave integrated circuit can be manufactured without impairing reliability. be able to. Further, because of the low dielectric constant and high Q value, for example,
It is most suitable as a material for circuit element substrates used in microwave and millimeter wave bands such as microwave and millimeter wave integrated circuits, support members for dielectric resonators, dielectric resonators, dielectric waveguides, and dielectric antennas. .

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a dielectric resonator control type microwave oscillator showing an example of a high frequency circuit element.

2] Sample No. It is an X-ray diffraction pattern which shows the crystal structure of 59.

3] Sample No. 5 is an X-ray diffraction diagram showing a crystal structure of 105. FIG.

[Explanation of symbols]

1. Dielectric porcelain 2 ... Support member 3 ... Porcelain substrate 4 ... strip line 5: Metal case

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01B 3/12 C04B 35/195

Claims (3)

(57) [Claims] 1. A composite oxide composed of Mg, Al and Si as metal elements, wherein xMgO.yAl ₂ O ₃ .zSiO ₂ represents the composition formula based on the molar ratio of each metal element oxide. , And y and z satisfy 10 ≦ x ≦ 40 10 ≦ y ≦ 40 20 ≦ z ≦ 80 x + y + z = 100, and 60 to 99.9 wt% of the main component, and Ce is Ce.
It has a relative permittivity of 0.1 to 40% by weight in terms of O _2.
7 or less, Q value at measurement frequency 10 GHz (room temperature) is 30
A dielectric porcelain composition characterized in that it is at least 00 and is used for high frequencies . 2. From Mg, Al and Si as metal elements
It is a composite oxide consisting of
The composition formula xMgO / yAl ₂ O ₃ ・ ZSiO ₂ And x, y and z are 10 ≦ x ≦ 40 10 ≦ y ≦ 40 20 ≦ z ≦ 80 x + y + z = 100 60 to 99.9% by weight of the main component satisfying
O ₂ Consists of 0.1-40% by weight, 1250-
Firing at 1450 ° C, relative permittivity 7 or less, measurement frequency
Q value at 10 GHz (room temperature) is 3000 or more
A dielectric porcelain composition characterized by: 3. A dielectric resonator formed by fixing a dielectric ceramic on a substrate via a supporting member, wherein the substrate and / or the supporting member has a dielectric ceramic composition according to claim 1 or 2. A dielectric resonator characterized by comprising a thing.