JP3336179B2 - 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 ceramic composition used at a high frequency such as a microwave and a millimeter wave, and relates to a microwave and a millimeter wave such as a microwave and a millimeter wave integrated circuit. High frequency dielectric ceramic compositions useful as materials for circuit element substrates, dielectric resonator supports, dielectric resonators, dielectric waveguides, dielectric antennas, etc. used in the band, and supports for dielectric ceramics 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 porcelain is fixed to a substrate via a supporting member may be adopted. For example,
As shown in FIG. 1, the dielectric resonator control type microwave transmitter attaches a dielectric porcelain 1 to a porcelain substrate 3 via a support member 2 and uses an electromagnetic field H leaking out of the dielectric porcelain 1. Then, it is connected to a strip line 4 provided on a porcelain substrate 3 and 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 relative dielectric constant and a low dielectric loss (t
an δ) must be used (a Q value is large). For this reason, conventionally, the relative permittivity of the support member material is about 7, and the Q value at the measurement frequency of 10 GHz is about 1500.
Forsterite of 0 is used, and the relative permittivity is about 10 and the measurement frequency is 10
Alumina porcelain having a Q value of 20,000 or more at GHz 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. Therefore, a material having a lower relative dielectric constant has been demanded.

On the other hand, porcelain such as glass ceramic and steatite 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 and has a high frequency band in recent years. With the spread of dielectric resonators, a low Q material having a higher Q value has been demanded.

Alumina porcelain, which is 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 line width varies greatly, 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, respectively, if the substrate thickness is constant. By using a substrate material having a low dielectric constant, the impedance can be increased, and therefore, a material having a lower dielectric constant has been demanded.

It is an object of the present invention to provide a high frequency dielectric ceramic composition having a lower dielectric constant than alumina and forsterite and a higher Q value than glass ceramic.

[0009]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, M
g, Al, made of Si only, xMgO-yAl ₂ O ₃ -zSiO the molar ratio composition formula of an oxide of these elements
When x, y, and z are within a certain range when expressed as ₂ , a high-frequency dielectric ceramic having a lower dielectric constant than alumina and forsterite and having a higher Q value than glass ceramic. It has been found that a composition can be obtained, which has led to the present invention.

That is, the dielectric ceramic composition for high frequencies of the present invention is a composite oxide composed of Mg, Al, and Si as metal elements, and the molar ratio composition formula of each metal element is xMgO-yAl _2. When expressed as O ₃ -zSiO ₂ , x, y, and z are 11 ≦ x ≦ 50, 0 <y ≦ 9, and 41 ≦ z ≦
80, x + y + z = 100, the main crystal phase is any of protoenstatite, cordierite, and cristobalite, the relative dielectric constant is 7 or less, and the Q value at a measurement frequency of 10 GHz is 2000 or more. is there.

The dielectric resonator according to the present invention is a dielectric resonator in which a dielectric ceramic is fixed on a substrate via a support member, wherein the substrate and / or the support member are made of a metal element such as Mg, Al. , A composite oxide comprising Si,
The molar ratio composition formula of the oxide of each metal element is xMgO-y
When expressed as Al ₂ O ₃ -zSiO ₂ , x, y and z are 1
1 ≦ x ≦ 50, 0 <y ≦ 9, 41 ≦ z ≦ 80, x + y +
z = 100, the main crystal phase is any of protoenstatite, cordierite, and cristobalite, the relative dielectric constant is 7 or less, and the measurement frequency is 1
The Q value at 0 GHz is 2000 or more.

[0012]

The dielectric ceramic composition of the present invention has a relative dielectric constant of 6
The Q value at 10 GHz can have a value of 2000 or more. By using such a low dielectric constant and high Q value dielectric porcelain, for example, as a support member or a substrate of a dielectric resonator, a high impedance can be obtained. High frequency circuit elements such as microwave integrated circuits can be manufactured without loss of reliability.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The dielectric porcelain composition of the present invention has a molar ratio composition formula of an oxide of a metal element represented by xMgO-yAl.
_When expressed as ₂ O ₃ -zSiO ₂ , the x, y, z are 11
≦ x ≦ 50, 0 <y ≦ 9, 41 ≦ z ≦ 80, x + y + z
= 100 is satisfied.

The reason why the composition of the dielectric ceramic composition for a high frequency wave of the present invention is limited to the above range is as follows. That is, the reason why the molar percentage x of MgO is set to 11 ≦ x ≦ 50 is that when x is smaller than 11, the sintered body is not densified,
If it exceeds 50, a good sintered body cannot be obtained and the Q value becomes low. The molar percentage x of MgO preferably satisfies 30 ≦ x ≦ 50 in order to make the Q value 3000 or more.

Further, the reason why y representing the molar percentage of Al ₂ O ₃ is set to 0 <y ≦ 9 is that when the amount y of Al ₂ O ₃ exceeds 9, the firing temperature range becomes narrow, and a good sintered body is obtained. It is difficult to obtain. Y indicating the mole percentage of Al ₂ O ₃
In order to make the Q value 3000 or more, it is preferable that 0 <y ≦ 5.

The z representing the molar percentage of SiO ₂ is 41 ≦ z
The reason for ≦ 80 is that if it is less than 41, a good sintered body cannot be obtained and the Q value is low, and if it exceeds 80, the sintered body cannot be densified. Z indicating the molar percentage of SiO ₂
Is 45 ≦ z ≦ 7 in order to make the Q value 3000 or more.
Desirably, it is 0.

The dielectric ceramic composition of the present invention has a molar ratio composition formula of xMgO-yAl ₂ O _3-
When expressed as zSiO ₂ , x, y, z are 30 ≦ x ≦ 50,
It is desirable to satisfy 0 <y ≦ 5, 45 ≦ z ≦ 70, and x + y + z = 100.

Further, in the present invention, the measurement frequency 10
The reason why the Q value at GHz is 2000 or more is that if the Q value is 2000 or more, it can sufficiently cope with recent high frequency band dielectric resonators.

Further, in the dielectric porcelain composition of the present invention, as shown in Table 1 and FIGS. 2 to 4, the main crystal phase is any of protoenstatite, cordierite, and cristobalite. , Forsterite, tridymite and the like may be precipitated. As a main crystal phase, precipitation of protoenstatite is desirable in that it has a high Q value. The precipitation phase varies depending on the composition, but as long as the above composition range is satisfied, the relative dielectric constant is 7 or less, and the Q value at 10 GHz is 2000 or more.

As shown in FIG. 1, the dielectric resonator according to the present invention comprises a dielectric ceramic 1 on a substrate 3 via a support member 2.
Is fixed, and the support member 2 or the substrate 3 or the support member 2 and the substrate 3 are made of the above-described dielectric ceramic composition.

The dielectric porcelain of the present invention comprises,
For example, MgCO ₃ powder, Al ₂ O ₃ powder, and SiO ₂ powder are weighed at a predetermined ratio, wet-mixed and dried, and the mixture is dried at 1100 to 1300 ° C. in the atmosphere.
After calcining with, it was pulverized. An appropriate amount of a binder is added to the obtained powder to form a compact.
It is obtained by firing at 00 ° C. The firing temperature must be strictly controlled at the optimum temperature in order to obtain a dense sintered body.

In the present invention, Mg, Al, Si
The raw material powders containing any of the inorganic compounds such as oxides, carbonates and acetates containing the respective metal elements, or the organic compounds such as organic metals, as long as they become oxides by firing good.

The dielectric ceramic composition of the present invention comprises only Mg, Al, and Si as metal elements.
There are cases where r, Ni, Fe, Cr, Ca, P, Na, Ti, etc. are mixed. In this case, too, 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.

Further, in the present invention, the average crystal grain size of the main crystal grains such as protoenstatite, cordierite, cristobalite and the like is desirably 0.5 to 5 μm from the viewpoint of having a high Q value. .

[0026]

EXAMPLE As raw material powder, 99% pure MgCO ₃ , 99.7% pure Al ₂ O ₃ , 99.4% pure SiO ₂
Using powders, these were weighed so that the sintered bodies had the composition shown in Table 1, wet-mixed for 15 hours, dried, calcined at 1200 ° C for 2 hours, and pulverized. An appropriate amount of a binder was added to the obtained powder and granulated.
It was molded under a pressure of 0 kg / cm ² to obtain a molded body having a diameter of 12 mm and a thickness of 8 mm. This molded product is put in air
It was fired at 1700 ° C. for 2 hours and polished to a diameter of 10 mm and a thickness of 5 mm to obtain a dielectric ceramic sample.

Using this sample, the dielectric constant and Q at a measurement frequency of 15 to 17 GHz were measured by the dielectric cylinder resonator method.
The value was measured. Regarding the Q value, 1 assuming that Qf = constant
The Q value at 0 GHz was determined. Table 1 shows the results.

[0028]

[Table 1]

According to Table 1, the dielectric ceramic composition for high frequencies according to the present invention has a low relative dielectric constant of 7 or less, and a dielectric constant of 10 or less.
It can be seen that the Q value at GHz shows a high value of 2000 or more.

Table 1 also shows the main crystal phases of the respective sintered bodies determined by X-ray diffraction. 2, 3, and 4 show X-ray diffraction charts of Samples No. 5, No. 8, and No. 13. FIG.

From these figures, it can be seen that cristobalite, protoenstatite and cordierite are precipitated as main crystal phases, and clinoenstatite, forsterite and the like are precipitated as other crystal phases.

[0032]

According to the dielectric ceramic composition for high frequency waves of the present invention, a ceramic having a low relative dielectric constant of 7 or less and a high Q value of 2000 or more at 10 GHz can be obtained. By using it for a support member or a substrate of a 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. 8 is an X-ray diffraction diagram showing a crystal structure of No. 8. FIG.

FIG. 13 is an X-ray diffraction diagram showing a crystal structure of No. 13.

[Explanation of symbols]

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

────────────────────────────────────────────────── ─── Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C04B 35/00-35/22 C04B 35/42-35/50 CA (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] 1. A composite oxide comprising Mg, Al, and Si as metal elements, wherein the molar ratio composition formula of each metal element oxide is represented by xMgO-yAl ₂ O ₃ -zSiO ₂ , , Y, z satisfy 11 ≦ x ≦ 500 0 <y ≦ 941 ≦ z ≦ 80 x + y + z = 100, and the main crystal phase is any of protoenstatite, cordierite, and cristobalite, and the relative dielectric constant is A high frequency dielectric ceramic composition, wherein the Q value is 7 or less and the Q value at a measurement frequency of 10 GHz is 2000 or more. 2. A dielectric resonator in which a dielectric ceramic 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.
Wherein the molar ratio composition formula of the oxide of each metal element is represented by xMgO—yAl ₂ O ₃ —zSiO ₂ , wherein x, y, and z are 11 ≦ x ≦ 500 <y. ≦ 941 ≦ z ≦ 80 x + y + z = 100, the main crystal phase is any of protoenstatite, cordierite, and cristobalite, the relative dielectric constant is 7 or less, and the Q value at a measurement frequency of 10 GHz is satisfied. A dielectric resonator, wherein the number is 2000 or more.