JP3330005B2 - High frequency 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 high frequency dielectric composition used in a high frequency region such as a microwave, a millimeter wave, etc. High frequency dielectric ceramic composition useful as material for circuit element substrate, dielectric resonator support, dielectric resonator, dielectric waveguide, dielectric antenna, etc. used in band, and support for dielectric ceramic The present invention relates to a dielectric resonator fixed to a substrate via a substrate.

[0002]

2. Description of the Related Art In high frequency circuit elements such as microwave and millimeter wave integrated circuits, a structure in which a dielectric resonant ceramic is fixed to a substrate via a support member may be adopted. For example, as shown in FIG. 1, a dielectric resonator control type microwave transmitter attaches a dielectric porcelain 1 to a porcelain substrate 3 via a support member 2, and an electromagnetic field leaking out of the dielectric resonator 1. H is used to couple to the strip line 4 provided on the porcelain substrate 3, and these are accommodated in a metal case 5.

In this type of high-frequency circuit, a resonance system with a high no-load Q is formed by controlling the electric field of the dielectric ceramic 1 from leaking through the support member 2. No. 2 has a low dielectric constant and a dielectric loss (ta
It is necessary to use a material having a small nδ) (a large Q value). For this reason, conventionally, forsterite having a relative dielectric constant of about 7 and a Q value of about 15,000 at a measurement frequency of 10 GHz has been adopted as a support base material, and the relative permittivity of the ceramic substrate 3 is mainly about 10 , Measurement frequency 10G
Alumina porcelain having a Q value of 20,000 or more at Hz has been employed (for example, see Japanese Patent Application Laid-Open No. 62-103904).

On the other hand, as a material having a low relative dielectric constant, 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 has been known (for example, Japanese Unexamined Patent Application Publication No. Sho 61-61). No. 234128)

[0005]

However, the relative dielectric constants of alumina and forsterite, which have been conventionally used, are about 10 and about 7, respectively, and with the recent spread of high frequency band dielectric resonators. Therefore, a lower dielectric constant material has been demanded.

On the other hand, a porcelain such as glass ceramic used as a low dielectric constant material has a relative dielectric constant as small as about 4 to 6, but has a Q value of about 1000 at 10 GHz, and has a dielectric material in a high frequency band in recent years. With the spread of resonators, a low Q material having a higher Q value has been demanded.

Further, alumina porcelain mainly used for a porcelain substrate of a resonator has a relatively high relative dielectric constant of about 10, and the line width becomes too small to form a high-impedance strip line (usually). (1 μm or less), there is a problem that disconnection occurs, the relative variation in line width increases, and the failure rate of the microwave integrated circuit increases.

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

As one means for solving the above problem, the present applicant has proposed a composite oxide comprising Mg, Al, and Si as metal elements, and the molar ratio composition formula of each metal element oxide is xMgO-yAl ₂ O. _When expressed as _3- zSiO ₂ , the x, y, and z are 10 ≦ x ≦ 40, 10 ≦ y ≦ 40, 20 ≦
z ≦ 80, x + y + z = 100, and a relative dielectric constant of 6
Below, and the Q value at the measurement frequency of 10 GHz is 2000
The above-described dielectric ceramic composition for high frequency and dielectric resonator have already been proposed (Japanese Patent Application No. 7-195211).

This high frequency dielectric ceramic composition was excellent in that it had a lower dielectric constant than alumina and forsterite, and had a higher Q value than glass ceramic. However, conventionally, since the firing temperature range of cordierite is extremely narrow, it is difficult to obtain a dense sintered body, and the above-described high frequency dielectric porcelain composition filed by the present inventors has been no exception.

An object of the present invention is to provide a high-frequency dielectric ceramic composition and a dielectric resonator which have a low dielectric constant, a high Q value at a measurement frequency of 10 GHz, and can improve firing conditions. .

[0012]

That is, the high frequency dielectric ceramic composition of the present invention comprises Mg, Al, Si as a metal element.
Wherein the composition formula of the molar ratio of the oxide of each metal element is xMgO—yAl ₂ O ₃ —zSiO
_When expressed as ₂ , the x, y, and z are 10 ≦ x ≦ 40, 1
Among the main components satisfying 0 ≦ y ≦ 40, 20 ≦ z ≦ 80, x + y + z = 100, Sr is 0.1 to 15 in terms of SrO.
% By weight, having a relative permittivity of 6 or less, and
The Q value at a measurement frequency of 10 GHz is 2000 or more. Further, in a dielectric resonator having a dielectric ceramic fixed on a substrate via a support member, the substrate and / or the support member are made of the above-described dielectric ceramic composition.

[0013]

The dielectric ceramic composition for a high frequency wave according to the present invention contains a predetermined amount of Sr in terms of SrO with respect to the above-mentioned main component, thereby obtaining a characteristic obtained by strictly controlling firing conditions such as firing temperature. Can be improved without greatly deteriorating the firing conditions. That is, while it is possible to obtain a low dielectric constant characteristic having a relative dielectric constant of 4 to 6 and a Q value of 2000 or more at a measurement frequency of 10 GHz, for example, a sintering temperature range of about 10 ° C. To the extent that it is easy to manufacture and mass productivity can be improved.

Further, by using such a dielectric ceramic having a low dielectric constant and a high Q value for a support member and / or a substrate of a dielectric resonator, for example, an integrated circuit for microwaves having a high impedance can be obtained. Can be manufactured without deteriorating the reliability.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The high frequency porcelain composition of the present invention comprises:
The compositional formula of the molar ratio xMgO-yAl ₂ O ₃ -zSiO ₂
Where x, y and z are 10 ≦ x ≦ 40 and 10 ≦ y
Those satisfying ≦ 40, 20 ≦ z ≦ 80, and x + y + z = 100 are the main components.

The main component composition of the high frequency ceramic composition of the present invention is limited to the above range for the following reason. That is, M
The reason why x representing the molar percentage of gO is set to 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. It is. In particular, x indicating the amount of MgO is desirably 15 to 35 mol% from the viewpoint that the Q value is 5000 or more.

Further, the reason why y indicating the molar percentage of Al ₂ O ₃ is set to 10 to 40 mol% is that when the amount y of Al ₂ O ₃ is smaller than 10 mol%, a good sintered body can be obtained. This is because the Q value is low, and when it exceeds 40 mol%, the relative dielectric constant is high. Y indicating the amount of Al ₂ O ₃ indicates that the Q value is 5;
From the viewpoint of being 000 or more, 17 to 35 mol% is desirable.

The reason why the molar percentage z of SiO ₂ is set to 20 to 80 mol% is that when z is smaller than 20 mol%, the relative permittivity becomes large, and when z exceeds 80 mol%, a good sintered body is obtained. No Q value is obtained. Z indicating the amount of SiO ₂ is Q
30 to 65 mol% from the viewpoint of setting the value to 5000 or more
Is desirable.

According to the present invention, the above-mentioned main component is Sr
Is contained in an amount of 0.1 to 15% by weight in terms of SrO. The reason why the content of SrO is limited to 0.1 to 15% by weight is that when the content of SrO is less than 0.1% by weight, the densification firing temperature is not widened, and when the content is more than 15% by weight, the dielectric This is because the loss increases and the Q value decreases. As the content of SrO increases, the densification firing temperature increases, but on the other hand, the relative dielectric constant increases and the Q value decreases. Therefore, these characteristics and the densification firing temperature balance It is desirable to determine the content.

The dielectric ceramic composition for high frequency wave of the present invention has Q
In order to set the value to 5000 or more, 15 ≦ x ≦ 35, 17 ≦ y ≦ 35, 30 ≦ z ≦ 65 in the main component composition.
It is desirable to satisfy the following condition. Furthermore, in order to make the Q value 7000 or more, 20 ≦ x ≦ 30, 17 ≦ y ≦ 30,
It is desirable to satisfy 0 ≦ z ≦ 60. In the present invention,
In particular, the composition of cordierite, ie, x = 22.2, y =
22.2, z = 55.6, and desirably contains 0.1 to 10% by weight of SrO.

When the Q value at a measurement frequency of 10 GHz is 2000
The reason for satisfying the above is that when the Q value is 2,000 or more, it is possible to sufficiently cope with recent high-frequency band dielectric resonators. The Q value is preferably as high as possible, but in particular, the measurement frequency is 10 GHz.
Is preferably 5000 or more.

In the dielectric porcelain composition of the present invention, the main crystal phase is cordierite.
Mullite, spinel, protoenstatite, clinoenstatite, cristobalite, forsterite,
Tridymite, safarin, SrAl ₂ Si ₂ O _{8 and the} like may be precipitated, but the precipitated phase differs depending on the composition.

As shown in FIG. 1, the dielectric resonator according to the present invention has a dielectric porcelain 1 fixed on a porcelain substrate 3 via a support member 2, and the support member 2 or the porcelain substrate 3, Alternatively, the support member 2 and the porcelain substrate 3 are made of the above-mentioned dielectric porcelain composition. In this case, a known material is used for the dielectric porcelain 1. As the dielectric ceramic 1, the dielectric ceramic composition of the present invention may be used.

The dielectric porcelain of the present invention comprises
For example, MgCO ₃ powder, Al ₂ O ₃ powder, SiO ₂ powder, and SrCO ₃ powder are weighed at a predetermined ratio, wet-mixed and dried, and this mixture is dried in air at 110 ° C.
After calcining at 0 to 1300 ° C., it was pulverized. It is obtained by adding an appropriate amount of a binder to the obtained powder and molding, and firing this molded body at 1200 to 1500 ° C. in the air.

The raw material powder made of a metal element such as Mg, Al, Si, or Sr may be an inorganic compound such as an oxide, a carbonate or an acetate, or an organic compound such as an organic metal. What is necessary is just what is formed as.

The dielectric porcelain composition of the present invention is composed of Mg, Al, Si, and Sr as metal elements.
Ca, Ba, Zr, Ni, Fe, Cr, P, Na, Ti
In some cases, a ceramic having a low dielectric constant and a high Q value can be obtained 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 ceramic of a dielectric resonator, a dielectric waveguide Any material such as a dielectric antenna and the like can be applied, but as described above, it is most suitable for a support member or a substrate of a dielectric resonator.

[0028]

EXAMPLE As raw material powder, 99% pure MgCO ₃ , 99.7% pure Al ₂ O ₃ , 99.4% pure SiO ₂
Powder and SrCO ₃ having a purity of 99.9% were weighed so that the sintered body had the composition shown in Table 1, wet-mixed for 15 hours, dried, and calcined at 1200 ° C. for 2 hours. After that, it was pulverized by a ball mill using alumina balls. The obtained powder was granulated by adding an appropriate amount of a binder, and the obtained powder was molded under a pressure of 1000 kg / cm ² to obtain a molded body having a diameter of 12 mm and a thickness of 8 mm. The molded body was fired in the air at 1200 to 1550 ° C. for 2 hours to obtain a diameter of 1 mm.
A 0 mm thick 6 mm dielectric porcelain sample was obtained.

Using this sample, the relative dielectric constant and Q value at a frequency of 10 GHz were measured by the dielectric cylinder resonator method, and the results are shown in Table 1.

[0030]

[Table 1]

According to Table 1, the dielectric ceramic composition for high frequency according to the present invention has a low relative dielectric constant of 6 or less and a high Q value at a measurement frequency of 10 GHz of 2000 or more. . Further, it can be seen that the range of the sintering temperature is expanded as the SiO ₂ content is increased.

FIG. 2 shows an X-ray diffraction chart of the sample No. 5. From FIG. 2, it can be seen that, in addition to cordierite, S
It can be seen that rAl ₂ Si ₂ O ₈ is precipitated.

[0033]

[Effect of the Invention] In the high-frequency dielectric ceramic composition of the present invention, the molar ratio composition formula xMgO-yAl ₂ O ₃ -zSiO
_When expressed as ₂ , the x, y, and z are 10 ≦ x ≦ 40, 10
A main component satisfying ≦ y ≦ 40, 20 ≦ z ≦ 80, and x + y + z = 100 contains a predetermined amount of Sr in terms of SrO, thereby having a low relative dielectric constant of 6 or less and 10 GHz.
In the state where the Q value at the time maintains a high Q value of 2000 or more,
The range of the densification firing temperature is expanded, and the productivity can be improved. And, for example, by using it for a support member or a substrate of a dielectric resonator, a high-frequency circuit element such as a high-impedance microwave integrated circuit can be manufactured without deteriorating reliability. In addition, since it has a low dielectric constant and a high Q value, for example, a substrate for a circuit element used in a microwave or millimeter wave band such as a microwave or a millimeter wave integrated circuit, a support for a dielectric resonator, a dielectric resonator, It is optimal as a material for dielectric waveguides, dielectric antennas and the like.

[Brief description of the drawings]

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

FIG. 5 is an X-ray diffraction diagram showing the crystal structure of Sample No. 5. FIG.

FIG. 3 is a ternary composition diagram showing a composition range of the dielectric ceramic composition for high frequency wave of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Dielectric porcelain 2 ... Support member 3 ... Porcelain board

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-333429 (JP, A) JP-A-9-48661 (JP, A) JP-A-8-77829 (JP, A) JP-A-4-78 338164 (JP, A) JP-A-2-38389 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 35/195 H01B 3/12

Claims (3)

(57) [Claims] 1. A complex oxide comprising metal elements Mg, Al, from Si, when the composition formula of the molar ratio of an oxide of each metal element expressed as _{xMgO-yAl 2 O 3 -zSiO 2} , wherein In the main component satisfying x ≦ y ≦ z 10 ≦ y ≦ 40 20 ≦ z ≦ 80 x + y + z = 100, Sr is 0.1 to 1 in terms of SrO.
A high frequency dielectric porcelain composition containing 5% by weight. 2. A device having a relative dielectric constant of 6 or less and a measurement frequency of 10
The Q value at GHz is 2000 or more
The dielectric ceramic composition for high frequencies according to claim 1 . 3. A dielectric resonator in which a dielectric porcelain is fixed on a substrate via a supporting member, wherein said substrate and / or said supporting member is composed of Mg, Al, Si as a metal element.
A composite oxide comprising, when the composition formula of the molar ratio of an oxide of each metal element expressed as _{xMgO-yAl 2 O 3 -zSiO 2} , wherein x, y, z is 10 ≦ x ≦ 40 10 ≦ In the main component satisfying y ≦ 40 20 ≦ z ≦ 80 x + y + z = 100, Sr is 0.1 to 1 in terms of SrO.
A dielectric resonator containing 5% by weight.