JP2004023772A - Dielectric resonator and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small sized dielectric resonator which can sufficiently follow transition to microwave strips. <P>SOLUTION: A dielectric resonator 11 is directly bonded on a circuit board 12. An electrode 13 for earth and a wiring 14 are formed in the circuit board 12. The dielectric resonator 11 is formed by the aero- deposition method, and the thickness thereof in the vertical direction in respect to the vertical direction of a substrate is 10-500 micrometers. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a high-speed digital communication such as a wireless LAN and a mobile phone, an intelligent transportation system such as a vehicle-mounted radar, a detecting device for detecting a moving object such as a human body, and a micro device mounted on a communication device used in a frequency control oscillator and the like. The present invention relates to a dielectric resonator for a wave band and a method for manufacturing the same.
[0002]
[Prior art]
Since a dielectric resonator involves radiation loss when placed in free space, it is often used with its periphery shielded by a conductor. As shown in FIG. 7 (a), both ends of the dielectric cylinder in the conductor cylindrical cavity are in contact with both ends of the cavity, as shown in FIG. 7 (a). (C), as shown in (d), a cavity image type resonator having a structure in which only one end of the cylinder is in contact with the conductor surface, as shown in (e). There are a parallel plate short-circuit type where the cavity diameter is infinite and the conductor side wall is removed, and a parallel plate open type and a parallel plate image type resonator as shown in FIG. These are important as resonators for microwave integrated circuits.
[0003]
In the production of a conventional dielectric resonator, an oxide ceramic powder having a dielectric constant of about several tens to one hundred and several tens is formed into, for example, a column shape, and then fired, and then ground with high dimensional accuracy. For a dielectric resonator up to several GHz, a fired body having a diameter and a thickness of several millimeters is used.
[0004]
The configuration often used at present is a kind of open-cavity resonator using TE ₀₁ δ mode, in which a dielectric resonator is supported by a support made of a low dielectric constant material in a conductor cover. is set up. Specifically, a method has been adopted in which a low dielectric constant support (spacer) is mounted on an insulating substrate with an adhesive, and a dielectric resonator is mounted on the support with an adhesive.
[0005]
Japanese Patent Application Laid-Open No. 2001-102824 proposes a method of attaching a dielectric resonator, in which a mounting portion made of a film portion is provided on an insulating substrate, and the dielectric resonator is mounted on the mounting portion. In this configuration, a gap is formed between the lower surface of the resonator and the insulating substrate, and the dielectric resonator is attached to the insulating substrate with an adhesive provided in the gap. The reason is that the variation in the thickness of the adhesive between the two causes the fluctuation of the resonance frequency due to the interaction between the dielectric resonator and the electrode part.
[0006]
In Japanese Patent No. 3168773, a concave portion is provided in a central portion of a thick film body (support), an adhesive is put into the concave portion, and a dielectric resonator is fixed to a substrate, and an electrode portion formed on the substrate and a dielectric resonator are fixed. A stable resonance frequency is obtained with the body resonator.
[0007]
These mounting methods show that it is necessary to employ a bonding step because the dielectric resonator is manufactured separately from the substrate as a fired body.
[0008]
Looking at the trend of dielectric resonators, the frequency of microwaves to be used is increasing as the number of users increases due to the rapid spread of mobile phones and PHS, etc., and the frequency band below 3 GHz is becoming tight. As the frequency is shifting to higher frequencies, the transition to the microwave band of 30 GHz or higher via wireless LAN (4.9 GHz), ETC (automatic toll road toll collection system, 5.8 GHz), etc. will be considered. It has become to. The size of the dielectric resonator depends on the frequency of the microwave used, and the size decreases as the frequency increases.
[0009]
Japanese Patent Application Laid-Open No. 2002-16410 discloses that as a dimension of a TE ₀₁ δ dielectric resonator element, the diameter of a cylindrical dielectric resonator element is about 4 to 5 mm for a 10 GHz band, and about 0.6 to 5 mm for a 60 to 70 GHz band. It is described as 0.7 mm.
[0010]
[Problems to be solved by the invention]
As described above, the size of the dielectric resonator in the microwave band may be as small as 1 mm or less, and in the conventional firing / grinding process, difficulties in handling, dimensional accuracy, and problems of mounting accuracy due to bonding occur. It is feared that.
[0011]
SUMMARY OF THE INVENTION An object of the present invention is to solve these problems in a dielectric resonator in which various problems arise in production because the shape is getting smaller and the dimensional accuracy is becoming stricter as the frequency becomes higher.
[0012]
[Means for Solving the Problems]
To achieve the above object, the present invention directly forms a thick-film ceramic dielectric in a substrate or chip.
Specifically, in the dielectric resonator according to the present invention, in a dielectric resonator installed on a circuit board, a main material is ceramics, and a thickness in a direction perpendicular to an installation surface on the substrate is 10 μm. ５００500 μm.
[0013]
In order to obtain a desired resonance frequency, not only the thickness but also the diameter is a factor. According to the aero deposition method described later, not only the thickness but also the diameter can be easily controlled.
[0014]
Further, the reason why the thickness is set to 10 μm to 500 μm is that 10 μm is considered to be the lower limit of the film thickness that is supposed to be achieved with good film thickness accuracy in the surface polishing of the post-processing, and is not achieved by the sol-gel method, the PVD method or the like It is. In addition, 500 μm is close to the upper limit that can be achieved by the aero method described below without any problem by the position method, and is a thickness that makes it difficult to grind and handle the fired body. This is an area of several tens of GHz.
[0015]
Further, the dielectric resonator is made of polycrystal by the aero deposition method, and the crystals constituting the structure have substantially no crystal orientation, and the interface between the crystals has a grain boundary layer made of a glass layer. Substantially does not exist, and a dielectric resonator having excellent mechanical and chemical properties such as hardness, abrasion resistance, and corrosion resistance is obtained.
In the present specification, the above polycrystal and the like are defined as follows.
(Polycrystalline)
In this case, it refers to a structure formed by bonding and accumulating crystallites. The crystallites substantially constitute a single crystal and have a diameter of usually 5 nm or more. However, in rare cases, for example, the fine particles are taken into the structure without being crushed, but they are substantially polycrystalline.
(Crystal orientation)
In this case, it refers to the degree of orientation of the crystal axis in a polycrystalline structure, and whether or not there is orientation is generally determined by measuring data of raw material powder fine particles which are considered to have substantially no orientation or powder X. JCPDS (ASTM) data used as standard data by line diffraction or the like is determined as an index.
The peak intensity of the three main diffraction peaks in this index, which includes the substances constituting the brittle material crystals in the structure, is taken as 100%, and the peak intensity of the most main peak in the measured data of the same substance of the structure is aligned with this. In this case, a state in which the peak intensities of the other two peaks are within 30% of the index value compared to the index value is referred to in the present case as substantially having no orientation.
(interface)
In the present case, it refers to a region constituting a boundary between crystallites.
(Grain boundary layer)
A layer having a certain thickness (usually several nm to several μm) located at an interface or a grain boundary in a sintered body, usually has an amorphous structure different from the crystal structure in a crystal grain, and in some cases, segregation of impurities. Accompany.
[0016]
In addition, the dielectric resonator of the present invention has a structure directly bonded to a circuit board or a chip mounted on the circuit board, for example, a spacer for resonating in a TE ₀₁ δ mode without using an adhesive, The joint portion forms an anchor portion, and further includes a structure in which the side wall of the dielectric resonator rises substantially perpendicularly to the surface of the circuit board.
In the present case, the anchor portion refers to irregularities formed at the interface between the base material and the structure, and in particular, changes the surface accuracy of the original base material at the time of forming the structure, instead of forming the unevenness on the base material in advance. It refers to the unevenness formed by being made.
[0017]
Further, in the method for manufacturing a dielectric resonator according to the present invention, an aerosol in which ceramic fine particles serving as a raw material of the dielectric resonator are dispersed in a gas is sprayed toward a circuit board or a chip installed on the circuit board. And causing the ceramic fine particles to collide with each other to directly form a film-shaped dielectric resonator in which the ceramic fine particle material is bonded to the circuit board or the spacer on the circuit board.
[0018]
Here, in the above manufacturing method, a method in which an aerosol in which ceramic fine particles are dispersed in a gas is sprayed on a substrate to form a ceramic structure on the substrate is called an aerosol deposition method. What is disclosed in patent No. 3265481 and international application patent WO 01/27348 A1 is known.
[0019]
For example, it is extremely difficult to achieve a thickness region of 500 μm or less by a conventional method of manufacturing a resonator by firing and grinding due to handling problems and the like. Therefore, in the present invention, an aerosol in which ceramic fine particles serving as a raw material of a dielectric resonator are dispersed in a gas is sprayed toward a circuit board or a chip placed on the circuit board to collide with the ceramic fine particles. Then, a film-shaped dielectric resonator formed by bonding a ceramic fine particle material is formed on a circuit board or a chip provided on the circuit board.
[0020]
In this manufacturing method, the step of forming the dielectric resonator is performed in a normal temperature environment. Here, the normal temperature is a temperature near room temperature that is sufficiently lower than the firing temperature of the ceramics, and substantially refers to a temperature of 200 ° C. or less.
[0021]
Here, a circuit board is one in which metal foil or conductor wiring is formed on an insulator such as Teflon, glass epoxy, or ceramics, or a dielectric film of an organic material or ceramic material is formed on a metal plate. Metal foil and conductor wiring are formed, and the location where the dielectric resonator is provided may be on an insulator, or may be on metal foil or conductor wiring. A chip installed on a circuit board is a support made of an insulator or conductor material with a dielectric constant lower than that of a dielectric resonator, or a shielding conductor made of box-shaped metal. One having a support formed therein is exemplified. The one in which the support is formed directly on the substrate is included in the aforementioned circuit board.
[0022]
The method of manufacturing a dielectric resonator according to the present invention includes the steps of spraying an aerosol in which ceramic fine particles serving as a raw material of the dielectric resonator are dispersed in a gas toward a circuit board or a chip mounted on the circuit board. In a method of forming a dielectric resonator by joining fine particles of ceramic to a circuit board or a chip placed on the circuit board by colliding fine particles, a through hole corresponding to the size of the dielectric resonator is formed. A mask provided on a plate is attached to a circuit board or a chip placed on the circuit board, and an aerosol is sprayed on the position of the through hole to form a dielectric resonator inside the through hole along the shape of the through hole.
[0023]
The dielectric resonator is particularly required to have dimensional accuracy. In the case of a firing method or the like, since dimensions change due to shrinkage due to firing, it is necessary to perform grinding after firing. In this means, since the dielectric resonator is formed at room temperature, no shrinkage or the like occurs, and the through-hole shape of the mask is used as a mold in advance and the dimensions are set in a desired shape, so that it can be manufactured with high precision. Can be. Although it is possible to fabricate the dielectric resonator by floating the mask from the substrate, it is more preferable to attach the mask to maintain the accuracy of the external shape of the resonator.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
FIGS. 1, 2 and 3 show cross-sectional views of some embodiments of the dielectric resonator. FIG. 4 is a schematic diagram of a manufacturing apparatus 40 (aerosol deposition apparatus) used to achieve this embodiment.
[0025]
In FIG. 1, the dielectric resonator 11 is arranged directly on a circuit board 12, and the circuit board 12 is provided with a ground electrode 13 and a wiring 14. The material of the circuit board may be an organic material such as Teflon or glass epoxy which is generally used, or a low dielectric constant ceramic such as alumina.
[0026]
In FIG. 2, the dielectric resonator 21 is disposed directly on the spacer portion 23 on the circuit board 22, and the circuit board 22 is formed with the ground electrode 24 and the wiring 25. The spacer portion 23 is formed of a dielectric material having a lower dielectric constant than the dielectric resonator 21, or is formed of a metal film. When the dielectric material is ceramics, a thick film directly formed on the circuit board 22 by using the aerosol deposition method is also conceivable.
[0027]
1 and 2 do not show a conductor cover normally provided around the dielectric resonator. In FIG. 3, the dielectric resonator 31 is disposed directly on the upper surface of a low-dielectric-constant spacer 33 formed inside a housing 32 of a conductor, and the housing 32 is bonded to a circuit board 34. It is adhered via an agent 35. The circuit board 34 has a ground electrode 36 and a wiring 37 formed thereon. Each of these dielectric resonators is formed by the aerosol deposition method, and has a thickness of 10 to 500 μm.
[0028]
Next, an embodiment of a method for manufacturing these dielectric resonators will be described with reference to the case of FIG. In FIG. 4, in a manufacturing apparatus 40, a nitrogen gas cylinder 401 is connected to an aerosol generator 403 containing submicron dielectric ceramic fine particles via a gas transfer pipe 402, and a formation chamber 405 is connected via an aerosol transfer pipe 404. It is connected to a nozzle 406 having an opening of 0.4 mm long and 5 mm wide, which is installed in the inside. A circuit board 408 mounted on an XY stage 407 is disposed beyond the nozzle 406. The formation chamber 405 is connected to a vacuum pump 409. A mask 410 having a through hole according to the size of the dielectric resonator is attached to the surface of the circuit board 408.
[0029]
A procedure for manufacturing a dielectric resonator using the manufacturing apparatus 40 having the above configuration will be described. The nitrogen gas cylinder 401 is opened, and nitrogen gas is introduced into the aerosol generator 403 through the transport pipe 402 to generate an aerosol containing dielectric fine particles. The aerosol is sent to the nozzle 406 through the transport pipe 404, and is ejected at a high speed from the opening of the nozzle 406. At this time, the operation of the vacuum pump 408 keeps the inside of the formation chamber 405 under a reduced pressure environment of several kPa.
[0030]
As shown in FIG. 5A, the dielectric fine particles collide at high speed with a circuit board 408 on which a mask 410 disposed at the tip of the opening of the nozzle 406 is attached, and the fine particles are crushed or deformed to cause particles or the like. The fragments are bonded to each other to form a structure made of a fine particle material on the substrate. The circuit board 408 is swung by the XY stage 407, and a dielectric structure is formed in a desired shape and area. The above operation is performed in a normal temperature environment.
[0031]
When the dielectric structure is laminated in the opening of the mask 410 as shown in FIG. 5B by the above operation, the mask 410 is removed as shown in FIG. As shown in FIG. 5D, the upper surface of the dielectric structure is ground (etched back), and the dielectric resonator 11 is obtained.
[0032]
(Example 1)
Using a manufacturing apparatus having a configuration similar to that of the above-described manufacturing apparatus 40, an oxide solid solution of barium, titanium, and tin having a particle diameter (SEM observation diameter) of 0.3 μm was used as the dielectric fine particles. The dielectric fine particles are obtained by first heat-treating a raw material powder for a commercially available fired microwave dielectric material near the firing temperature, finely crushing the resulting material, and then pulverizing it with a planetary mill to have a desired particle size. . The circuit board used was a glass epoxy board plated with copper foil. The gas used in the production was high-purity nitrogen, the flow rate was 4 L / min, and a plastic film having a thickness of 100 μm and a circular hole having a diameter of about 2.5 mm was used as a mask.
[0033]
FIG. 6 shows a cross-sectional profile of the resulting cylindrical dielectric structure. It can be seen that the structure having a thickness of 13 μm is formed such that the outer surface of the structure stands up substantially at right angles (in the range of 80 ° to 100 °) with respect to the substrate surface.
[0034]
When the dielectric constant of this structure was measured with an impedance analyzer 4194A manufactured by Hewlett-Packard, it was εr: 47 (at 1 MHz), which was almost the same as the dielectric constant of the separately prepared fired body. When the hardness of this structure was measured with a load of 50 gf using a microhardness measuring device DUH-W201 manufactured by Shimadzu Corporation, a value of 499 Hv was obtained, and the structure was not a green compact but had a strength equivalent to a fired body. I understand.
[0035]
[Effects of the present invention]
According to the present invention, it is possible to obtain a small-sized dielectric resonator that can sufficiently follow a shift to a microwave band of, for example, 30 GHz or more.
Further, in the present invention, since no adhesive is interposed, a stable resonance frequency can be obtained without fluctuation of the resonance frequency due to variation in the thickness of the adhesive. Since there is no firing process, a dielectric resonator having an accurate shape can be manufactured by using a mask without considering deformation during firing, and handling is easy.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a circuit board on which a dielectric resonator according to the present invention is mounted. FIG. 2 is a cross-sectional view of a circuit board on which a dielectric resonator according to another embodiment is mounted. FIG. FIG. 4 is a cross-sectional view of a circuit board on which a dielectric resonator is mounted. FIG. 4 is a schematic view of an apparatus for manufacturing a dielectric resonator according to the present invention. FIG. 5A to FIG. FIG. 6 is a view showing an example of a method of manufacturing a resonator. FIG. 6 is a view showing a cross-sectional shape profile of the dielectric resonator according to the present invention. FIGS. 7A to 7F show the structure of a general dielectric resonator. Diagrams [Description of symbols]
11, 21, 31 ... dielectric resonator, 12, 22, 34 ... circuit board, 13, 24, 36 ... ground electrode, 14, 25, 37 ... wiring, 23, 33 ... spacer, 32 ... housing, 35 adhesive, 40 manufacturing apparatus, 401 nitrogen gas cylinder, 402 gas transport pipe, 403 aerosol generator, 404 aerosol transport pipe, 405 forming chamber, 406 nozzle, 407 XY stage, 408 circuit Substrate, 409: vacuum pump, 410: mask.

Claims (8)

In a dielectric resonator installed on a circuit board, a main material is ceramics, and a thickness in a direction perpendicular to an installation surface on the substrate is 10 μm to 500 μm. 2. The dielectric resonator according to claim 1, wherein the dielectric resonator is polycrystalline, crystals constituting the structure have substantially no crystal orientation, and a glass layer is formed at an interface between the crystals. A dielectric resonator substantially free of a grain boundary layer comprising: 3. The dielectric resonator according to claim 1, wherein the dielectric resonator is directly bonded to the circuit board or a chip mounted on the circuit board without using an adhesive. 4. The dielectric resonator according to claim 2, wherein an anchor portion into which a part of the dielectric resonator bites is formed on a surface of the circuit board or a chip provided on the circuit board. And a dielectric resonator. 5. The dielectric resonator according to claim 1, wherein a side wall of the dielectric resonator rises substantially perpendicularly to a surface of the circuit board. An aerosol obtained by dispersing ceramic fine particles serving as a raw material of a dielectric resonator in a gas is sprayed toward a circuit board or a chip mounted on the circuit board so that the ceramic fine particles collide with the circuit board or the circuit board. A method for manufacturing a dielectric resonator, comprising a step of directly forming a film-shaped dielectric resonator in which the ceramic fine particle material is bonded to a chip mounted thereon. 7. The method for manufacturing a dielectric resonator according to claim 6, wherein the step of forming the dielectric resonator is performed in a normal temperature environment. 8. The method of manufacturing a dielectric resonator according to claim 6, wherein a mask having a through-hole corresponding to the size of the dielectric resonator is provided on the circuit board or the circuit board. And forming the dielectric resonator inside the through-hole along the shape of the through-hole by spraying the aerosol on the position of the through-hole. Method.

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