JP3309048B2 - 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, for example, a circuit element substrate used in a microwave and a millimeter wave integrated circuit, and the like. High frequency dielectric ceramic composition useful as a material for a dielectric resonator support, a dielectric resonator, a dielectric waveguide, a dielectric antenna, etc., and a dielectric in which the dielectric ceramic is fixed to a substrate via the support It relates to a resonator.

[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 generates a magnetic field H leaking out of the dielectric porcelain 1. It has a structure in which it is connected to a strip line 4 provided on a porcelain substrate 3 using a metal case 5.

In this type of high-frequency circuit, a resonance system having a high no-load Q is formed by controlling the leakage of the electromagnetic field of the dielectric ceramic 1 through the support member 2. For the member 2, it is necessary to use a material having a low relative dielectric constant and a small dielectric loss (tan δ) (a large Q value). For this reason, conventionally, as a material of the support member, the relative dielectric constant is about 7, and the Q value at the measurement frequency of 10 GHz is about 1
5000 forsterite is used, and alumina porcelain having a relative dielectric constant of about 10 and a Q value of 20,000 or more at a measurement frequency of 10 GHz is mainly used as a material of the porcelain substrate 3 (for example, Japanese Patent Application Laid-Open No. -10390
No. 4 gazette).

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, and a glass material is added. The relative dielectric constant obtained by this is 4 to
6. A glass ceramic having a Q value of about 1000 at a measurement frequency of 10 GHz is known (for example, Japanese Patent Application Laid-Open No.
No. 234128).

[0005]

However, with the alumina and forsterite conventionally used, the Q value at a measurement frequency of 10 GHz is 20,000 or more and 1500 or more.
Although it is as high as 0, the relative dielectric constant is about 10 and about 7, respectively. With the recent spread of dielectric resonators in a high frequency band, a material having a lower relative dielectric constant has been required.

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, 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 when the thickness of the substrate is constant. In addition, by using a substrate material having a low relative dielectric constant,
Dance can be enhanced, and therefore, a material having a lower dielectric constant has been demanded.

As one means for solving the above-mentioned 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).

The high frequency dielectric ceramic composition comprises alumina,
It was an excellent material having a lower dielectric constant than forsterite and a higher Q value than glass ceramic.

Conventionally, however, cordierite has a very narrow sintering temperature range, so that it is difficult to obtain a dense sintered body, and the dielectric ceramic composition for high frequency application previously filed by the inventor was 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. .

[0013]

That is, the high frequency dielectric ceramic composition of the present invention comprises Mg, Al, Si as a metal element.
A composite oxide comprising an oxide xMgO · a molar ratio composition formula according yAl ₂ O ₃ · zSiO ₂ for each metal element
When x, y, z are 10 ≦ x ≦ 40, 10 ≦
Ga is added and contained in an amount of 0.1 to 10 parts by weight in terms of Ga ₂ O ₃ with respect to 100 parts by weight of the main component satisfying y ≦ 40, 20 ≦ z ≦ 80, and x + y + z = 100.

Further, the dielectric resonator according to the present invention is a dielectric resonator comprising a dielectric ceramic fixed on a substrate via a supporting member, wherein the substrate and / or the supporting member are:
A composite oxide composed of Mg, Al, and Si as metal elements, and the molar ratio composition formula of the oxide of each metal element is xM
When expressed as gO.yAl ₂ O ₃ .zSiO ₂ , the above x,
y and z are 10 ≦ x ≦ 40, 10 ≦ y ≦ 40, 20 ≦ z ≦
80, and 0.1 to 10 parts by weight of Ga in terms of Ga ₂ O ₃ with respect to 100 parts by weight of the main component satisfying x + y + z = 100.

[0015]

In the dielectric ceramic composition of the present invention, a predetermined amount of Ga in terms of Ga ₂ O ₃ is contained with respect to the above-mentioned main component, whereby the firing conditions such as the firing temperature are strictly controlled. The firing conditions can be improved without greatly deteriorating the characteristics. That is, the dielectric constant is 4 to 6 and the measurement frequency is 1
It is possible to obtain a dielectric ceramic having a low dielectric constant having a Q value of 2000 or more at 0 GHz and, for example, a firing temperature range of about 10 ° C. can be expanded to about 50 ° C., thereby facilitating production. , Mass productivity can be improved.

Further, by using such a dielectric porcelain having a low dielectric constant and a high Q value for a supporting member and / or a substrate of a dielectric resonator, for example, the characteristics can be improved and a high impedance microporous material can be obtained. A high-frequency circuit element such as a wave integrated circuit can be manufactured without deteriorating reliability.

[0017]

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

The composition of the high frequency ceramic composition of the present invention is limited to the above range for the following reason. That is,
The reason why x indicating the molar percentage of MgO 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.

The reason why y representing the mole 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.

When the molar percentage z of SiO ₂ is 20 ≦ z ≦ 80
The reason for the mol% is 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 indicating 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, the a Ga with respect to the 100 parts by weight of the main component was 0.1 to 10 parts by weight additives contained in terms _of Ga ₂ O ₃ is the content of at terms _of Ga ₂ O ₃ 0 If the amount is less than 1 part by weight, the densification firing temperature is not widened,
If the amount is more than 0 parts by weight, the dielectric loss increases and the Q value decreases. As the content of Ga increases, the densification firing temperature increases, but on the other hand, the relative permittivity increases and the Q value decreases. Therefore, the content of Ga is determined in consideration of these characteristics and the densification firing temperature. It is desirable to determine the amount.

The dielectric ceramic composition for high frequency wave of the present invention has Q
To make the value 5000 or more, 15 ≦ x ≦ 35, 17
It is desirable to satisfy ≦ y ≦ 35 and 30 ≦ z ≦ 65. In the present invention, in particular, the composition of cordierite, ie, x
= 22.2, y = 22.2, z = 55.6 and Ga ₂ O ₃
Is desirably contained in an amount of 0.1 to 10% by weight.

In the present invention, Q at a measurement frequency of 10 GHz
The value satisfies 2000 or more, which means that the Q value is 200
This is because if the number is 0 or more, it can sufficiently cope with a dielectric resonator in a high frequency band in recent years. The Q value is preferably as high as possible.
It is desirable that the Q value at 0 GHz is 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, GaAlO ₃ , MgGa ₂
O _{4 and the} like may precipitate, but the precipitated phase differs depending on the composition.

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. 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 Ga ₂ O ₃ powder are weighed at a predetermined ratio, wet-mixed, and dried.
After calcining at 0 to 1300 ° C., it was pulverized. The resulting powder was added with an appropriate amount of binder, a known method, for example, formed by press molding, the molded body oxidizing atmosphere such as air, Ar, in a reducing atmosphere such as N ₂ 1,300 to 1
It is obtained by baking at 450 ° C. for 5 minutes to 10 hours.

The dielectric porcelain composition of the present invention is composed of Mg, Al, Si, and Ga as metal elements.
a, Ba, Zr, Ni, Fe, Cr, P, Na, Ti and the like may be mixed.

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.

[0029]

EXAMPLE As raw material powder, 99% pure MgCO ₃ , 99.7% pure Al ₂ O ₃ , 99.4% pure SiO ₂
Powder, 99.9% pure Ga ₂ O ₃ powder was prepared, and Mg
Using CO ₃ , Al ₂ O ₃ , and SiO ₂ powders, the main component composition was weighed so as to have the composition shown in Table 1, and thereafter, Ga ₂ O ₃ was added to Table 1 with respect to 100 parts by weight of the main component. The mixed powder was added in the amount indicated, wet mixed with a ball mill using ZrO ₂ balls for 15 hours, dried, calcined at 1200 ° C. for 2 hours in the air, and then pulverized. The obtained powder was granulated by adding an appropriate amount of a binder, and the obtained powder was press-molded under a pressure of 1000 kg / cm ² to obtain a compact having a diameter of 12 mm and a thickness of 8 mm. This molded body is fired at 1270-1550 ° C. for 2 hours in the atmosphere,
A dielectric ceramic sample having a diameter of 10 mm and a thickness of 6 mm 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.

[0031]

[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 5.6 or less and a high Q value at a measurement frequency of 10 GHz of 2540 or more. I understand.

Incidentally, FIG. 11 shows an X-ray diffraction chart. From FIG. 2, it can be seen that mullite is precipitated in addition to cordierite.

[0034]

According to the dielectric ceramic composition for high frequency wave of the present invention, the sintering conditions can be improved, and the ceramic material has a low relative dielectric constant of 6 or less and a high Q value of 2000 or more at 10 GHz. Can be easily obtained, for example, by using it for a support member or a substrate of a dielectric resonator, thereby improving characteristics and manufacturing a high-frequency circuit element such as a high-impedance microwave integrated circuit without deteriorating the reliability. be able to. 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. 11 is an X-ray diffraction diagram showing the crystal structure of Sample No. 11.

[Explanation of symbols]

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

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-9-295861 (JP, A) JP-A-9-286662 (JP, A) JP-A-9-165257 (JP, A) JP-A 8- 69715 (JP, A) JP-A-63-151655 (JP, A) JP-A-53-84199 (JP, A) JP-A-9-48661 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 35/195 H01B 3/12 H01G 4/12 H01P 7/10

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 , wherein x , y, with respect to z is 100 parts by weight of the main component which satisfies 10 ≦ x ≦ 40 10 ≦ y ≦ 40 20 ≦ z ≦ 80 x + y + z = 100, the Ga Ga ₂
A dielectric ceramic composition for high frequencies, characterized in that it contains 0.1 to 10 parts by weight in terms of O ₃ . 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.
A composite oxide comprising, when the molar ratio composition formula 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 ≦ y ≦ 40 20 ≦ z ≦ 80 x + y + z = 100 with respect to 100 parts by weight of the main component which satisfies the Ga Ga ₂
A dielectric resonator containing 0.1 to 10 parts by weight in terms of O ₃ .