JP3147085B2 - High frequency filter and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high-frequency filter which is a component of 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 high frequency filter of the present invention can be used for communication devices, radar devices, measuring devices, and the like.
The frequency band used is applicable to circuits for high frequencies of several GHz or more.

[0002]

2. Description of the Related Art Conventionally, there has been known a technique for forming a high-frequency filter by arranging a dielectric resonator near a conductor line formed on a dielectric substrate. For example, Japanese Unexamined Patent Publication
Japanese Patent No. 334413 discloses a high-frequency filter in an MIC in which an insulating film is formed on a surface of a semiconductor substrate, a conductor line is formed on the insulating film, and a dielectric resonator is fixed near the conductor line with an adhesive. A vessel is disclosed.

[0003]

The technique of mounting a dielectric resonator near a conductor line as described above is basically an excellent technique, but it is necessary to fix it with an adhesive while performing positioning. As the number of man-hours increases, the characteristics tend to vary, which is not always suitable for mass production. Also, when designing a filter circuit for use in a frequency band of several tens of GHz, the size of the substrate becomes extremely small. In such a small circuit, a slight dimensional error greatly affects the overall electrical characteristics. Become.

Therefore, it is indispensable to adjust the frequency characteristic after manufacturing. However, in the prior art, this largely depends on experience, and is not suitable for producing a uniform product, and there are problems such as poor reproducibility. Was.

It is an object of the present invention to provide a high-frequency filter which is excellent in mass productivity, hardly causes variation in characteristics, and has uniform and stable high-frequency characteristics.

It is another object of the present invention to provide a high-reliability high-frequency filter capable of improving mechanical working accuracy and mechanical strength.

It is still another object of the present invention to provide a high frequency filter having a higher Q factor.

[0008]

SUMMARY OF THE INVENTION The present invention is characterized in that mechanical precision and mechanical strength are improved by embedding a dielectric resonator in a substrate. A high Q value is obtained by using a material having a lower dielectric constant than the base dielectric substrate as a material in contact with the above surface.

Specifically, in the high-frequency filter of the present invention, a conductor line is formed on the surface of a dielectric substrate, a plurality of dielectric resonators are embedded near the conductor line, and a lower portion of the dielectric resonator is provided. Or the periphery of the dielectric resonator is covered with a material having a dielectric constant lower than that of the base dielectric substrate.

According to the present invention, since the dielectric resonator, which is a component of the high-frequency filter, is embedded and integrated in the substrate, the mechanical strength and mechanical accuracy are improved, and there is no variation and stability. The high frequency filter described above can be configured.

Further, since the material in contact with at least one surface of the dielectric resonator is made of a material having a lower dielectric constant than the dielectric substrate as a base, it is possible to constitute a high-frequency filter having a higher Q value. it can.

As the dielectric substrate in the present invention, it is preferable to use a ceramic, particularly a low-temperature sintered glass ceramic. As the low dielectric constant material, plastic, particularly, polytetrafluoroethylene is preferably used.

[0013]

FIG. 1 is a view showing a first embodiment of a high-frequency filter according to the present invention. FIG. 1 (a) is a plan view thereof, and FIG. 1 (b) is a sectional view taken along line AA. . In FIG.
1 is a dielectric substrate, 2 is a dielectric resonator, 3 is a microstrip line, 4 is a ground conductor, and 5 is a cavity. The dielectric substrate 1 is formed of a low-temperature sintered glass ceramic. This low-temperature sintered glass ceramic is a composite of borosilicate glass and alumina, but may be a composite of lead borosilicate glass and alumina. The size of the substrate is approximately 10 × when the thickness of the conventional substrate is t.
4 × 2 tmm.

Three holes are formed in the surface of the dielectric substrate 1, and these holes have a small diameter in the middle as shown in FIG. The dielectric resonator 2 is buried in the larger diameter hole 7 on the surface side, and the smaller diameter hole 8 becomes the cavity 5. Dielectric resonator 2 Dielectric constant is dielectric substrate 1
By providing the cavity 5, the upper and lower surfaces of the dielectric resonator 2 are in contact with air lower than the dielectric constant of the dielectric substrate 1. The value can be further increased, and a high-frequency filter with small insertion loss can be obtained.

Next, the manufacturing process of the high frequency filter of the present invention will be described. First, several low-temperature sintered glass ceramics
A green sheet is prepared, a ground conductor is printed on one of the green sheets, and holes are formed in a predetermined number of the green sheets by punching. At that time, two kinds of sheets are made, a sheet with a large diameter hole and a sheet with a small diameter hole.

Next, the green sheet having the holes formed thereon and the green sheet on which the ground conductor 4 is printed are placed on a surface having a large hole diameter so that the center lines of both holes are overlapped, and a sheet having a large diameter is disposed below the green sheet. The sheets are stacked in order such that a sheet having a small hole diameter is arranged, and further a green sheet on which a ground conductor is printed is arranged therebelow. After lamination, the dielectric resonator 2 processed into a cylindrical shape is fitted into the hole 7 having the larger hole diameter, and is fired at a time. By firing, the low-temperature sintered glass-ceramic substrate shrinks, and the dielectric resonator 2 has the larger diameter hole 7.
And is embedded in the dielectric resonator 2.
A cavity 5 is formed by a hole 8 having a smaller diameter.

The firing temperature of the substrate 1 is selected to be lower than the firing temperature of the dielectric resonator 2 so as not to affect the dielectric resonator 2. In this embodiment, the firing temperature of the low-temperature sintered glass ceramic substrate is about 900 ° C. while the firing temperature of the dielectric resonator is about 1600 ° C. After that, using a print mask, the gold conductor paste is printed at a predetermined position on the substrate surface, and baked to form the microstrip line 3.

FIGS. 3A and 3B show a high-frequency filter according to a second embodiment of the present invention, wherein FIG. 3A is a plan view thereof, and FIG.
Is a sectional view taken along the line A-A. In FIG. 3, the same numbers as those in FIG. 1 indicate the same materials. Also in this embodiment, the size of the substrate 1 is approximately 10 × 4 × 2 tmm, and the substrate 1 is a multi-layer substrate formed of a low-temperature sintered glass ceramic similarly to the first embodiment, and has a surface. 3
Individual holes are formed. These holes are formed by punching a hole in the green sheet, laminating the green sheet on which the ground conductor is printed, and firing.

In the second embodiment, the dielectric resonator 2 covered with a plastic material, for example, a low dielectric constant material 6 such as polytetrafluoroethylene, except for the upper surface, is inserted into the hole. The dielectric resonator 2 is fixed via a low dielectric constant material 6 by an adhesive applied to the inner wall of the hole. Further, a microstrip line 3 is formed near the dielectric resonator 2.

Low dielectric constant material 6 covering dielectric resonator 2
For example, a Teflon-based material other than polytetrafluoroethylene, benzocyclobutene, a polyimide-based material, an epoxy-based material, or the like can be used. The thickness of the coating is 0.
The thickness is preferably about 5 to 1 mm, whereby a high Q value can be obtained.

[0021]

According to the present invention, the substrate and the dielectric resonator are integrally formed, and a portion made of a material having a lower dielectric constant than the substrate material is provided below or around the dielectric. , A high-precision, high-Q value high-frequency filter can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a high-frequency filter according to a first embodiment of the present invention. (A) is the top view, (b) is the AA sectional drawing.

FIG. 2 is a diagram illustrating the shape of a hole formed in a substrate of the high-frequency filter of FIG.

FIG. 3 is a diagram showing a high-frequency filter according to a second embodiment of the present invention. (A) is the top view, (b) is the BB sectional drawing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dielectric substrate 2 Dielectric resonator 3 Microstrip line 4 Ground conductor 5 Cavity 6 Low dielectric constant material 7 Large diameter hole 8 Small diameter hole

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-7-58505 (JP, A) JP-A-6-334413 (JP, A) JP-A-11-145577 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01P 1/20 H01P 7/10 H01P 11/00

Claims (5)

(57) [Claims] 1. A high-frequency filter in which a conductor line is formed on a surface of a dielectric substrate and at least one dielectric resonator is arranged near the conductor line, wherein the dielectric resonator is provided on the dielectric substrate. The perimeter except the top surface is embedded in the drilled hole ,
A cavity is provided between the lower surface of the dielectric resonator and the dielectric substrate.
A high-frequency filter characterized by having a pattern formed thereon . 2. A conductor line is formed on a surface of a dielectric substrate.
And at least one dielectric resonator is provided near the conductor line.
In the arranged high-frequency filter, the dielectric resonator has a hole formed in the dielectric substrate.
In addition, the periphery except the upper surface has a lower dielectric constant than the dielectric substrate.
Characteristically embedded with a dielectric material interposed
And high frequency filter. 3. The dielectric material is plastic.
3. The high frequency filter according to claim 2, wherein: 4. A plurality of low-temperature sintered glass ceramic groups.
A predetermined number of green sheets among the lean sheets
Drill a hole of the first diameter by punching
Number of green sheets by punching
Forming a hole having a second diameter smaller than the diameter of the green sheet;
The hole of the first diameter and the hole of the second diameter overlap
Laminating so as to form a stepped hole, and forming the first diameter hole of the laminated green sheet.
A dielectric resonator machined into a cylindrical shape is inserted into it.
And the laminated green sheet into which the dielectric resonator is fitted.
Baking the dielectric resonator into holes of the first diameter.
And a step of fixing the filter in a filter.
Method of manufacturing a corrugator. 5. A plurality of low-temperature sintered glass ceramic groups.
A predetermined number of green sheets among the lean sheets
Punching a hole of a predetermined diameter by unching, and forming the plurality of green sheets on the surface side by the predetermined diameter.
By firing and laminating so that holes are formed,
Sheets of a step of a glass ceramic substrate, the baking and the plants which are formed on a glass ceramic substrate
Dielectric resonance processed into a cylindrical shape in a fixed diameter hole
The dielectric constant of the glass ceramic substrate is higher than that of the glass ceramic substrate.
Bonding and fixing with low dielectric constant material
A method for manufacturing a high-frequency filter, comprising: