JPH11145703A - High frequency filter and its adjustment method for frequency characteristic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To unitformize and stabilize a high frequency characteristic and to inexpensively manufacture a filter by engaging dielectric parts and magnetic material parts into plural holes provided for a dielectric board and printing and formed conductors on the surface of the dielectric board. SOLUTION: Dielectric parts 2 are engaged into the plural large holes in the board 1 and the magnetic material parts 3 are engaged into the plural small holes. The conductors are printed on the surface of the board 1 and become micro strip lines 4. It is desirable that the dielectric substrate 1 be formed of plastic, especially polytetrafuloroethylene. A reinforcing board for preventing the mechanical distortion of the board 1 is provided at the back of the dielectric board 1. The materials of the magnetic material parts 3 are hard ferrite. Heat is applied to the magnetic material parts 3, and the temperature is once raised higher than the Curie temperature of the materials, thus demagnetizing the ports. Magnetic field is applied from the outside, while the parts are cooled, thus changing a magnetized state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency filter using a high-frequency integrated circuit or a microwave integrated circuit (MIC) formed by mounting or forming a plurality of circuit components on a substrate. The present invention is used for a communication device, a radar device, a measuring device, and others. Although the present invention has been developed with the aim of using it for high-frequency circuits exceeding 10 GHz, it does not limit the frequency to be used.
It can also be used for circuits in the frequency band of 0 GHz or less.

[0002]

2. Description of the Related Art A technique for forming a microwave integrated circuit (MIC) by attaching a plurality of circuit components to a ceramic substrate using an adhesive is known. This technique is disclosed in Japanese Patent Application Laid-Open No. Hei 6-334413, which is a prior application of the present applicant, in which an insulating film is formed on the surface of a semiconductor substrate, and a conductor line is formed on the insulating film. Further, a dielectric resonator is mounted near the conductor line, and the dielectric resonator is described as being fixed to a substrate by an adhesive.

Further, a technique is known in which a hole is formed in an alumina substrate before firing, a ferrite is fitted into the hole, and the ferrite is fixed to the substrate by firing.
No. 8486. This is a useful technique for attaching ferrite to a ceramic substrate, and the present invention is also in the flow of this technique, but this conventional technique is a technique for attaching ferrite alone to an alumina substrate, The idea of arranging mutually related circuit components and integrating them as an integrated circuit has not yet been reached. They have not even conceived mounting dielectric components on the same substrate. Further, the technical idea of using hard ferrite as the ferrite and magnetizing the hard ferrite in accordance with the electrical characteristics of the circuit has not been reached.

[0004]

On the other hand, a high frequency band exceeding 10 GHz has been used for various devices. In particular, the frequency of an automobile radar device or a distance measuring device is allocated to the 60 GHz band or 70 GHz band, and a high-frequency filter having a large amount, low cost, and uniform characteristics can be used stably in this frequency band. Manufacturing technology is required. Also,
Ferrite technology has been improved, and hard ferrites having a high coercive force with low loss and adjustable anisotropic magnetic field can be used.

The technique of mounting a dielectric resonator near a conductor line as described above is basically an excellent technique. However, since an adhesive is used for the work, the number of work steps is increased, and the characteristics are likely to vary, which is not always suitable for mass production. In addition, several tens G
When a filter circuit or an antenna circuit used in a frequency band of Hz is designed, a circuit component to be mounted on the circuit board is, for example, a cylindrical dielectric component having a diameter of about 2 to 3 millimeters, and a magnetic component is less than that. May be smaller. In order to correctly bond a component having such a size to a substrate, a working accuracy of several tens of μm is required. For this purpose, a machine tool having a high degree of machine precision is required, and mass production of such a circuit requires considerable capital investment.

As described above as a conventional example, the technique of mounting ferrite on an alumina substrate before firing is found to be a very useful technique when a ferrite part having a diameter of 2 mm is tested. In order to manufacture a filter circuit or an antenna circuit in a frequency band of several tens of GHz as described above, a desired filter circuit cannot be designed using only a ferrite component as disclosed in the above publication. Regardless, even if a plurality of such components are arranged on a single substrate and circuit connection is performed, the work requires a large number of man-hours, and connection loss and reliability of connection points pose problems. . For that purpose, it is necessary to form a microstrip line of a conductor having substantially the same size or an integrated circuit in which dielectric components are integrally integrated on the same substrate.

When a high-frequency filter used in a frequency band of several tens of GHz as described above is designed by a microwave integrated circuit, the size of the substrate becomes extremely small. In one example, it is 8 mm × 3 mm × 0.3 mm. In such a small circuit, a slight dimensional error greatly affects the entire electrical characteristics, and it is essential to adjust the frequency characteristics after manufacturing. In the prior art, this largely depends on experience, and is not suitable for producing a uniform product, and has problems such as poor reproducibility. further,
When making adjustments to mechanically cut magnetic parts,
The adjustment is limited to one direction, and cannot be undone when it is cut too much, causing a decrease in the production yield.

The present invention has been made in such a background, and provides a high-frequency filter using a microwave integrated circuit (MIC) in which both a dielectric component and a magnetic component are arranged on one substrate. With the goal. An object of the present invention is to improve mechanical working accuracy as compared with a structure in which individual components are arranged on a substrate and connected. SUMMARY OF THE INVENTION An object of the present invention is to improve the mechanical working accuracy to make the high-frequency characteristics uniform and stable. An object of the present invention is to provide a high-reliability high-frequency filter. An object of the present invention is to provide a high-frequency filter having stable electric characteristics and capable of producing electric characteristics uniformly. An object of the present invention is to provide a high-frequency filter using a high-frequency integrated circuit with a small number of manufacturing steps. An object of the present invention is to provide a high-frequency filter that can be manufactured at low cost by mass production. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for adjusting electrical characteristics while observing electrical characteristics after manufacturing, and in particular, a method for adjusting the frequency characteristics of a high-frequency filter capable of reversibly adjusting the characteristics.
SUMMARY OF THE INVENTION An object of the present invention is to make it possible to adjust frequency characteristics after manufacturing, and to improve the manufacturing yield of products.

[0009]

A first aspect of the present invention is a high-frequency filter, wherein a plurality of holes are provided in a dielectric substrate,
A dielectric component serving as a resonator and a magnetic component that adjusts the resonance frequency of the dielectric component by a magnetic field generated by the resonator are fitted into the holes, and a conductor is printed on the surface of the dielectric substrate. It is characterized by the following. The dielectric substrate is made of plastic, particularly preferably polytetrafluoroethylene. It is preferable to provide a reinforcing plate on the back surface of the dielectric substrate to prevent mechanical distortion of the substrate. This dielectric substrate may be made of ceramic.

It is convenient to adjust the frequency characteristics by using hard ferrite as the material of the magnetic component attached to the substrate.

A second aspect of the present invention is a method for adjusting the frequency characteristic of the high-frequency filter, wherein the material of the magnetic component is hard ferrite, and a magnetic field is applied to the magnetic component from outside. The method is characterized by including a step of changing the magnetized state by applying the voltage. In the step of changing the magnetized state, it is preferable to apply a magnetic field while heating or cooling the magnetic component. It is effective to apply heat to the magnetic component to raise the temperature once more than the Curie temperature of the material to demagnetize, and then apply a magnetic field while cooling to effect magnetization. The step of changing the magnetization state is preferably performed while observing the frequency characteristics of the high-frequency filter.

Another frequency characteristic adjusting method includes a step of mechanically shaving a part of the magnetic component. In this case, it is desirable that the height of the magnetic component be set in advance so as to protrude from the surface of the substrate.

When an organic material or plastic is used as the substrate, polytetrafluoroethylene is preferred.

When a ceramic substrate is used as the substrate, a plurality of holes are formed in the green sheet at the stage of the green sheet before the ceramic substrate is fired, and circuit components are fitted into the holes, respectively. A ceramic substrate is formed by firing at a temperature not higher than the deformation temperature and not lower than the firing temperature of the green sheet, and in the firing process of the ceramic substrate, utilizing the property that the diameter of the hole shrinks, the circuit component is used. Is fixed to the ceramic substrate. In this way, both the magnetic component and the dielectric component can be integrated into one substrate.

The material of the magnetic component is hard ferrite, and the temperature at which the green sheet is fired is lower than the temperature at which the hard ferrite is fired. Then, after the ceramic substrate is fired, the hard ferrite may be magnetized by applying a magnetic field to the hard ferrite after the temperature of the hard ferrite becomes close to or lower than the Curie temperature. The temperature for firing the ceramic substrate is 800 to 1200 ° C. The Curie temperature of hard ferrite varies depending on the type of material, but is about 400 to 700 ° C. further,
The magnetization is adjusted by adjusting the magnetic field applied to the hard ferrite. It is desirable to adjust the magnetization state while observing the electrical characteristics of the integrated circuit.

Before firing the ceramic substrate, a plurality of holes are formed by punching at the green sheet stage, circuit components are fitted into the holes, and thereafter firing is performed. By forming holes by punching, the mutual positional relationship can be easily manufactured with high accuracy. Since the mutual positional relationship is such that the shape is shrunk by firing, the final shape after firing is adjusted by a plurality of trial productions so as to have a desired shape. Once this adjustment is made, many integrated circuits of the same shape can be manufactured without individually adjusting the shape.

The size of the hole in the green sheet is also adjusted by a plurality of trial productions so that the magnetic component and the dielectric component are firmly fixed after firing. Once adjusted, many integrated circuits of the same shape can be manufactured uniformly.

The height of the circuit component (the length in the direction perpendicular to the surface of the ceramic substrate) is preferably equal to or greater than the thickness of the substrate. In the case of a dielectric component, it is possible to work even when the height of the component is higher than the thickness of the substrate, in which case the degree of freedom of the shape of the component is increased, and various circuits can be designed. .

It is most preferable that the shape of the hole provided in the green sheet is circular, and the shape of the circuit component fitted in the hole is cylindrical at least at the portion in contact with the substrate, since the tightening force of the component becomes uniform. . Although it is possible to make the outer surface shape of the circuit component into an elliptical cylinder shape,
In this case, the number of times of the repeated test is increased so as to be optimally fixed.

It is necessary to select the firing temperature of the green sheet so that the properties of the magnetic parts, especially the hard ferrite, do not change. However, as a result of the test, when firing at a temperature higher than the Curie temperature of the hard ferrite, Also,
It was found that the desired characteristics were obtained by lowering the temperature after completion of the firing and, when the temperature became lower than the Curie temperature of the hard ferrite, applying a magnetic field to the hard ferrite and adjusting the magnetic arrangement again. Since the firing temperature and Curie temperature of hard ferrite are not uniform depending on the type of ferrite, the temperature of the firing step and the temperature of the magnetizing step are selected according to the properties of the respective materials. It is not always necessary to set the firing temperature to be equal to or higher than the Curie temperature of the hard ferrite.

When the magnetization is performed after the completion of firing, the magnetization can be performed after the sample reaches room temperature. However, if the temperature is lowered from a relatively high temperature, the magnetization is easily performed to a desired value. Further, after the magnetization is performed once, the high frequency circuit is electrically operated, and the state of the magnetization can be changed to be strong or weak while observing the characteristics.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION

[0023]

1 is a view showing a high-frequency filter according to an embodiment of the present invention, wherein FIG. 1 (a) is a plan view, FIG. 1 (b) is a front view, and FIG. is there. In this embodiment, the size of the substrate is approximately 10.times.4.times.0.3 mm, and the substrate is formed of ceramic. Three large holes and ten small holes are drilled in the substrate 1, the dielectric component 2 is fitted into each of the large holes, and the magnetic component 3 is fitted into the small holes. A conductor is printed on the surface of the substrate 1 to form a microstrip line 4.

The manufacturing process will be described in more detail.
A hole is made in the green sheet of the ceramic substrate before firing by punching. Then, the dielectric component 2 and the magnetic component 3 each formed into a cylindrical shape are fitted into the holes. The material of the magnetic component 3 is hard ferrite. Thus, the circuit component is fitted in the state of the green sheet of the substrate, and then the ceramic is fired. The firing temperature is selected to be lower than the hard ferrite firing temperature. Using a print mask, the gold conductor paste is printed and baked to form the microstrip line 4. After the firing, the magnetic component 3 is naturally cooled in the air, and when its surface temperature reaches about 600 ° C., the magnetic component 3 is magnetized by applying a magnetic field to the magnetic component 3 while continuing the cooling.

The relative permittivity (εr) of the ceramic substrate is about 7
The dielectric component 2 is formed of a Ba-based ceramic and has a relative dielectric constant (εr) of about 24.

The magnetization of the magnetic component 3 is performed by individually applying a magnetic field. At this time, while observing the frequency characteristics (frequency loss characteristics) of the high-frequency filter, the magnetization is repeatedly changed so that the characteristic curve approaches the designed value.

FIG. 2 is a diagram for explaining the frequency characteristics of the high-frequency filter of this embodiment. The solid line is the design value of this high frequency filter. The dotted line shows the final characteristics of the high-frequency filter of this embodiment. The broken line is a final characteristic diagram as a comparative example when the dielectric component 2 and the magnetic component 3 are arranged on a ceramic substrate using a manipulator by a conventional method and fixed by bonding.

(Second Embodiment) A manufacturing process of a high-frequency filter using an organic material-based substrate will be described. Drill a hole about 0.05 to 0.1 mm larger than the diameter of the part to be fitted into the board. An adhesive is applied to the inner wall of the hole, and the magnetic component and the dielectric component are fitted and bonded. Thereafter, a metal conductor is formed on one surface of the substrate by plating so that the magnetic component and the dielectric component have a desired positional relationship.
A metal conductor is formed on the entire opposite surface of the substrate.

(Third Embodiment) Another manufacturing process of a high-frequency filter using an organic material-based substrate will be described. A magnetic component is stuck on the metal foil with a conductive adhesive, and a dielectric component is stuck with a conductive adhesive or an insulating adhesive. An organic resin is applied and cured on the same surface of the metal foil as the surface to which the component is adhered so that the height is substantially the same as the magnetic component and the dielectric component. Thereafter, a metal conductor is formed on the surface of the organic resin by plating so as to have a desired positional relationship with the magnetic component and the dielectric component.

(Fourth Embodiment) A process of manufacturing another high-frequency filter using an organic material-based substrate will be described. A hole having a diameter about 0.05 to 0.1 mm larger than the diameter of the component to be fitted to the substrate is formed. On the other hand, a magnetic component is attached on a metal foil with a conductive adhesive, and a dielectric component is attached with a conductive adhesive or an insulating adhesive. The component attached to the metal foil is inserted into a hole in the substrate, and the metal foil is bonded to the surface of the substrate with an adhesive. Thereafter, a metal conductor is formed by plating on the opposite surface of the substrate from the surface to which the metal foil is bonded so as to have a desired positional relationship with each component.

[0031]

As described above, according to the present invention, a dielectric component and a magnetic component are integrated on a single circuit board with high mechanical accuracy by forming holes in the board. Can be. Therefore, a large number of high-frequency filters having uniform characteristics in a frequency range of several tens of GHz can be manufactured. In addition, by adjusting the magnetization using hard ferrite as in the present invention, the frequency characteristics of the filter can be adjusted after manufacturing, and the adjustment can be performed reversibly. Therefore, there is an effect that the production yield of the product is improved and highly accurate adjustment can be performed.

[Brief description of the drawings]

FIG. 1 is a structural diagram of a high-frequency filter according to an embodiment of the present invention. (A) is a plan view, (b) is a front view, and (c) is a CC sectional view.

FIG. 2 is a diagram illustrating frequency characteristics of the high-frequency filter according to the embodiment of the present invention.

[Sign]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Dielectric component 3 Magnetic component 4 Microstrip line

Claims (11)

[Claims] 1. A plurality of holes are provided in a dielectric substrate. In each of the holes, a dielectric component serving as a resonator and a magnetic component that sets a resonance frequency of the dielectric component by a magnetic field generated by the resonator are provided. A high-frequency filter, wherein the filter is fitted and a conductor is formed on a surface of the dielectric substrate. 2. The high frequency filter according to claim 1, wherein said dielectric substrate is made of plastic. 3. The high frequency filter according to claim 2, wherein said dielectric substrate is made of polytetrafluoroethylene. 4. The high-frequency filter according to claim 3, wherein a reinforcing plate for preventing mechanical distortion of the dielectric substrate is provided on a back surface of the dielectric substrate. 5. The high frequency filter according to claim 1, wherein said dielectric substrate is made of ceramic. 6. The high frequency filter according to claim 1, wherein the material of the magnetic component is hard ferrite. 7. A plurality of holes are provided in a dielectric substrate. In each of the holes, a dielectric component serving as a resonator and a magnetic component that sets a resonance frequency of the dielectric component by a magnetic field generated by the resonator are provided. In the method of adjusting the frequency characteristics of a high-frequency filter in which a conductor is printed and formed on the surface of a dielectric substrate, the material of the magnetic component is hard ferrite, and a magnetic field is applied to the magnetic component from outside. And changing the state of magnetization by adjusting the frequency characteristic of the high-frequency filter. 8. The step of changing the magnetized state includes applying heat to the magnetic component to raise the temperature to a temperature equal to or higher than the Curie temperature of the material, thereby demagnetizing the magnetic component, and applying a magnetic field while cooling to magnetize the magnetic component. The method for adjusting the frequency characteristics of a high-frequency filter according to claim 7. 9. The method according to claim 7, wherein the step of changing the magnetized state is performed while observing the frequency characteristics of the high-frequency filter. 10. A plurality of holes are provided in a dielectric substrate. In each of the holes, a dielectric component serving as a resonator and a magnetic component that sets a resonance frequency of the dielectric component by a magnetic field generated by the resonator are provided. A method for adjusting the frequency characteristics of a high-frequency filter in which a conductor is printed and formed on the surface of the dielectric substrate, comprising the step of mechanically shaving a part of the magnetic component. Method. 11. The method according to claim 10, wherein the height of the magnetic component is set in advance so as to protrude from the surface of the substrate.