JPH06232612A - Dielectric resonator - Google Patents

Abstract

PURPOSE:To obtain a dielectric resonator coping with miniaturization, formed with high precision and whose resonance frequency is stable by forming an internal electrode into a plated shape in the dielectric resonator in which the internal electrode is formed in a dielectric body and an outer electrode is formed around the dielectric body. CONSTITUTION:A plate-shaped internal electrode 2 is formed in the middle of a dielectric body 1 and an outer electrode 3 is formed around the dielectric body 1. One end of the internal electrode 2 is connected to the outer electrode 3 at a connection part to form a short-circuit end and the other end is not connected to the outer electrode 3 to form an open end. The dielectric body 1 and the internal electrode 2 are formed by laminating and pressing dielectric sheets including at least a dielectric material and electrode sheets formed by printing the internal electrode 2 to a prescribed position on the dielectric sheet. Furthermore, a width W1 of the internal electrode 2 is selected to be 20-80% of a width W2 of the dielectric body 1, the thickness of the internal electrode 2 is selected to be 3-30mum, the thickness of the dielectric sheet is selected to be 50-1000mum, and the thickness of the outer electrode 3 is selected to be 3-30mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric resonator, and more particularly to its shape.

[0002]

2. Description of the Related Art For example, a combination of a plurality of dielectric resonators is used as a bandpass filter for an automobile radio telephone or a portable radio telephone. As shown in FIG. 5, the dielectric resonator has an inner electrode 13 and an outer electrode 14 on an inner wall and an outer wall of a dielectric 11 having a cavity 12 at the center.
Are formed. The dielectric resonator shown in FIG. 5 is a quarter-wave TEM mode dielectric resonator. A cross-sectional view of this dielectric resonator is shown in FIG. 6. The internal electrode 13 is connected at one end to the external electrode 14 by the connecting portion 15 to form the short-circuit end 11a, and the other end of the internal electrode 13 is connected to the external electrode 14. The open end 11b is formed without being connected.

Such a dielectric resonator is manufactured as follows. First, a dielectric resonator made of a dielectric material and a polymer material is molded into a shape of a dielectric resonator having a cavity at the center by a method such as uniaxial press molding or injection molding. Next, the molded product is fired to obtain a ceramic dielectric. Then, an internal electrode and an external electrode are formed on the inner wall and the outer wall of this dielectric by a method such as baking a conductive paint or applying electroless plating. At this time, since the external electrode is formed on the entire surface around the dielectric, the internal electrode is connected to the external electrode at both ends. Therefore, the external electrode connected to one end of the internal electrode is removed to make it an open end, and the external electrode formed on the cavity is also removed at the short-circuit end which is the other end so that both ends of the cavity become openings. Then, a dielectric resonator as shown in FIG. 5 is obtained.

[0004]

In recent years, miniaturization of communication devices such as the above-mentioned automobile radio telephones and portable radio telephones has been promoted, and in dielectric resonators used as these components. Is also desired to be smaller, specifically, the outer dimensions are 2 mm or less, and the internal electrode dimensions are 1 m.
Those of about m or less are required.

However, since the dielectric of the dielectric resonator having a cavity at the center is molded by uniaxial press molding or injection molding as described above, there is a limit to miniaturization of the dielectric resonator. That is, in such a molding method, there is a limit to the size of the cavity formed in the molded product due to the problem of the strength of the mold, and the dielectric body forming the dielectric resonator having the above dimensions is molded. Is difficult to do. Therefore, there is a limit to miniaturization of the dielectric resonator as described above.

The resonance frequency of such a dielectric resonator is determined by the outer dimensions of the dielectric resonator. A resonant frequency f ₀ when the length of the dielectric resonator as shown in FIG. 6 is L, the relative permittivity of the dielectric is ε _r , and the speed of light is C
Is represented as follows. f ₀ = C / (4L√ε _r )

Therefore, in order to stabilize the resonance frequency f ₀ , it is necessary to increase the dimensional accuracy of the length L. Furthermore, due to the miniaturization of the dielectric resonator as described above, higher dimensional accuracy is required. However, in the dielectric resonator using the dielectric formed by uniaxial press molding or injection molding as described above, the accuracy of the length L is low, and it is difficult to achieve the required dimensional accuracy.

Therefore, the present invention has been proposed in view of the conventional circumstances, and it is an object of the present invention to provide a dielectric resonator which is adaptable to miniaturization, is formed with high precision, and has a stable resonance frequency. To aim.

[0009]

Means for Solving the Problems As a result of intensive studies made by the present inventors in order to achieve the above-mentioned object, when a dielectric and an internal electrode are formed by lamination, a cavity at the center of the dielectric is not necessary. It has been found that the size of the dielectric resonator can be reduced and high-precision processing can be performed, so that the resonance frequency can be stabilized.

That is, according to the present invention, in a dielectric resonator having an internal electrode formed in a dielectric and an external electrode formed around the dielectric, the internal electrode is plate-shaped. To do.

Further, according to the present invention, in the above-described dielectric resonator, the dielectric and the internal electrode are printed by printing the dielectric sheet containing at least the dielectric material and the internal electrode at a predetermined position on the dielectric sheet. It may be formed by laminating and press-bonding the formed electrode sheets and then firing.

Further, in the present invention, in the dielectric resonator as described above, the width W ₁ of the internal electrode is set to the width W of the dielectric.
It may be a 20% to 80% of _2, the thickness of the internal electrode 3
μm to 30 μm, the thickness of the dielectric sheet is 50 μm to 10 μm
The thickness of the external electrode may be set to 00 μm and the thickness of the external electrode may be set to 3 μm to 30 μm.

At this time, if the width W _{1 of the} internal electrode is less than 20% or more than 80% of the width W ₂ of the dielectric material, the Qu value decreases.

Further, if the thickness of the internal electrode is less than 3 μm, sufficient conductivity cannot be obtained, and if it is more than 30 μm, the adhesion to the dielectric is deteriorated. Furthermore, if the thickness of the dielectric sheet is less than 50 μm, the strength of the dielectric sheet itself becomes insufficient and the number of laminated layers increases, which is not preferable. On the other hand, if the thickness of the dielectric sheet is more than 1000 μm, cracks are likely to occur during the formation of the dielectric sheet, and it is difficult to obtain a good dielectric sheet. Furthermore, if the thickness of the external electrode is less than 3 μm, the conductivity of the conductor is not sufficient, the Qu value is lowered, and the thickness of the external electrode is reduced to 30 μm.
If it is thicker than μm, it takes time to form an electrode and productivity is lowered, which is not preferable.

When the dielectric sheet and the electrode sheet are laminated and pressure-bonded, a hydrostatic pressure method may be applied, and the pressure at that time is 50 MPa or more, preferably 10 MPa.
It is 0 MPa or more.

[0016]

According to the present invention, in a dielectric resonator in which an internal electrode is formed in a dielectric and an external electrode is formed around the dielectric, the internal electrode has a plate shape, and the dielectric and the internal Since the electrodes are formed by laminating and pressing a dielectric sheet containing at least a dielectric material and an electrode sheet having internal electrodes formed by printing at predetermined positions on the dielectric sheet, uniaxial press molding or There is no restriction at the time of molding unlike the molding by injection molding, the size of the dielectric and the internal electrode can be changed relatively freely, and the dielectric and the internal electrode having high dimensional accuracy can be formed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments to which the present invention is applied will be described below with reference to the drawings. First, the dielectric resonator of this example is shown in FIG. As shown in FIG. 1, in the dielectric resonator of this embodiment, a plate-shaped internal electrode 2 is formed in the center of a dielectric 1, and an external electrode 3 is formed around the dielectric 1.
Are formed. The dielectric resonator A- in FIG.
A cross-sectional view of the surface indicated by A'is shown in FIG. 2, in which the internal electrode 2 is connected to the external electrode 3 by the connecting portion 4 at one end and the short-circuit end 1a is formed.
Is formed, and the other end of the internal electrode 2 is not connected to the external electrode 3 and forms the open end 1b.

The external dimensions of the dielectric resonator of this embodiment are as follows, and the width W _{1 of the} internal electrode 2 shown in FIG. ₁ is 0.8.
mm, dielectric width W ₂ is 2.0 mm, dielectric resonator length L is 5.59 mm, internal electrode thickness d ₁ is 5 μm, external electrode thickness d ₂ is 5 μm, dielectric thickness D ₃ is 1.0
mm.

The dielectric resonator of this example was manufactured as follows. First, a dielectric material was manufactured. BaCO
₃ 13.9 mol%, Bi ₂ O ₃ 1.5 mol%, Na
₂ O ₃ is 12.7 mol%, Sm ₂ O ₃ is 3.2 mol%,
TiO ₂ was mixed at a ratio of 68.7 mol%, mixed and pulverized in a wet ball mill for 15 hours, calcinated in the atmosphere at 1000 ° C. for 5 hours to obtain a dielectric material powder, and further pulverized in a wet ball mill for 15 hours. Thus, a dielectric material fine powder having a particle size of 1 μm or less was obtained.

Next, the dielectric material fine powder was mixed with a binder made of a polymer material to prepare a dielectric slurry. That is, with respect to 70% by weight of the dielectric material fine powder,
Polyvinyl butyral (PVB) which is a binder and dibutyl phthalate (DBP) which is a plasticizer are added so that the total amount of both is 30% by weight, and toluene, methyl ethyl ketone and butanol are added thereto, and mixed in a ball mill for 5 hours. Then, a dielectric slurry was prepared.

Next, the dielectric slurry was formed into a dielectric sheet (so-called green sheet) having a thickness of 200 μm using a doctor blade. Ten such sheets were prepared, and one of them was formed by screen printing so that the width after drying was 0.8 mm and the thickness was 5 μm, and dried to obtain an electrode sheet. The internal electrodes are composed of a conductive paste. In this embodiment, the composition of the conductive paste was as follows. That is, 100 parts by weight of the conductive powder, 40 parts by weight of the binder, 50 parts by weight of the solvent, and Pd: Ag as the conductive powder.
= 7: 3 was used for the alloy, polyvinyl butyral was used as the binder, and ethylene glycol was used as the solvent. In addition, ethyl cellulose or the like can be used as the binder, and ethyl ether, toluene, xylene or the like may be used as the solvent.

Then, as shown in FIG. 3, after stacking four dielectric sheets 5 as described above, the electrode sheet 6 on which the internal electrodes 2 are formed is placed at the center of the dielectric to be obtained later. As described above, five dielectric sheets 5 were further laminated thereon, and a pressure as shown by an arrow P in FIG. 4 was applied by pressure by a hydrostatic pressure method to perform pressure bonding to obtain a laminated body. The pressure at this time was 100 MPa or more.

The laminated body thus formed is punched so that the width W ₂ of the dielectric body is 2.0 mm and the length L of the dielectric resonator is 5.59 mm as shown in FIG. Was molded. The molding may be performed by grinding with a grindstone. Then, the laminated body is degreased in the air at 500 ° C. for 10 hours and fired in the air at 1200 ° C.
Got

Next, the external electrode 3 was formed on the entire periphery of the dielectric 1 as described above by electroless Cu plating. And
The external electrode 3 connected to one end of the internal electrode 2 was removed by polishing to form the open end 1b, and the dielectric resonator shown in FIG. 1 was obtained. The resonant frequency of the dielectric resonator of this example was 1.5 GHz, and the unloaded Q was 200.

That is, in the dielectric resonator of this embodiment, it is possible to obtain a resonance frequency of 1.5 GHz with a size of 5 mm in length, 2 mm in width and 1 mm in height.

Therefore, in the dielectric resonator according to the present embodiment, the internal electrode is formed in the dielectric, and the external electrode is formed around the dielectric. Forming the dielectric and the internal electrode by laminating and pressing a dielectric sheet containing at least a dielectric material and an electrode sheet having the internal electrode formed by printing at a predetermined position on the dielectric sheet. Achieves miniaturization without degrading the characteristics of the dielectric resonator,
It also achieved high dimensional accuracy.

[0027]

As is apparent from the above description, according to the present invention, a dielectric resonator in which an internal electrode is formed in a dielectric and an external electrode is formed around the dielectric is Since the internal electrodes are plate-shaped, the size of the dielectric and the internal electrodes can be changed relatively freely, and the dielectric resonator can be downsized.

Further, according to the present invention, in the above dielectric resonator, the dielectric and the internal electrode are printed by printing the dielectric sheet containing at least the dielectric material and the internal electrode at a predetermined position on the dielectric sheet. It may be formed by laminating and press-bonding the formed electrode sheets and then firing, and there are no restrictions at the time of molding such as molding by uniaxial press molding or injection molding, and the size of the dielectric and internal electrodes. Is relatively free to change, and can be made smaller. Furthermore, since it is possible to form a dielectric and an internal electrode having high dimensional accuracy and then perform mechanical processing, it is possible to achieve extremely high dimensional accuracy. It is possible to stabilize the resonance frequency and improve the manufacturing yield to improve the productivity.

Further, in the present invention, in the above-described dielectric resonator, the width W ₁ of the internal electrode is set to the width W of the dielectric.
It may be a 20% to 80% of _2, the thickness of the internal electrode 3
μm to 30 μm, the thickness of the dielectric sheet is 50 μm to 10 μm
The thickness of the external electrode may be set to 00 μm, and the thickness of the external electrode may be set to 3 μm to 30 μm. By satisfying these conditions, it is possible to obtain a higher quality dielectric resonator.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a dielectric resonator to which the present invention is applied.

FIG. 2 is a sectional view showing an embodiment of a dielectric resonator to which the present invention is applied.

FIG. 3 is a plan view showing a method of manufacturing the embodiment of the dielectric resonator to which the present invention is applied, in the order of steps, and showing a step of laminating a dielectric sheet and an electrode sheet.

FIG. 4 is a plan view showing a step of pressure-bonding a dielectric sheet and an electrode sheet.

FIG. 5 is a perspective view showing a conventional dielectric resonator.

FIG. 6 is a cross-sectional view showing a conventional dielectric resonator.

[Explanation of symbols]

 1 ... Dielectric 2 ... Internal electrode 3 ... External electrode 4 ... Connection part 5 ... Dielectric sheet 6 ... Electrode sheet

Claims (4)

[Claims] 1. A dielectric resonator in which an internal electrode is formed in a dielectric and an external electrode is formed around the dielectric, wherein the internal electrode is plate-shaped. vessel. 2. A dielectric sheet and an internal sheet by stacking and pressing a dielectric sheet containing at least a dielectric material and an electrode sheet having internal electrodes formed by printing at predetermined positions on the dielectric sheet, followed by firing. The dielectric resonator according to claim 1, wherein electrodes are formed. 3. The width W _{1 of the} internal electrode is _{2 which} is the width W ₂ of the dielectric.
It is 0% -80%, The dielectric resonator of Claim 1 characterized by the above-mentioned. 4. The thickness of the internal electrode is 3 μm to 30 μm, the thickness of the dielectric sheet is 50 μm to 1000 μm, and the thickness of the external electrode is 3 μm to 30 μm. Dielectric resonator.