JPH11340713A - Dielectric resonance member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dielectric resonance member of a high Q value and excellent handleability by changing the structure of an outer conductor (short- circuit conductor) formed on a short-circuit end face. SOLUTION: In this dielectric resonance member 10, a through-hole 2 passed through from the open end face of a columnar dielectric block 1 to the short- circuit end face is formed at the block 1, an inner conductor 3 composed of a conductor film is formed on the inner wall surface of the through-hole 2 and an outer conductor 4 composed of the conductor film is formed on the short-circuit end face and respective side faces of the dielectric block 1 respectively. Then, in the outer conductor (short-circuit conductor 40) on the short- circuit end face, a thick film metal conductor film 42 is put on a thin film metal base conductor layer 41.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric resonance member comprising a plurality of dielectric filters or a dielectric resonance member which forms a dielectric dielectric resonator by itself.

[0002]

2. Description of the Related Art A dielectric filter is a component in which a plurality of dielectric resonance members are joined to form a predetermined frequency pass band, and is used as a filter for a high-frequency band-pass filter or an antenna filter of a communication device. Many filters are used.

[0003] A dielectric resonator is a component that serves as resonance means of a resonance circuit using a single dielectric resonance member.
It is frequently used in the resonance circuit of a high-frequency oscillation circuit of a communication device.

As shown in the external perspective view of FIG. 1, such a dielectric resonance member has, for example, a through-hole penetrating from one end face (open end face) to the other end face (short-circuit end face). 2, an inner conductor 4 which is a conductor film formed on the inner wall surface of the through hole 2 of the columnar dielectric block 1, the other end face (short-circuit end face) of the columnar dielectric block 1 and four The outer conductor 4 is a conductor film formed on the side surface (especially, the outer conductor formed on the short-circuit surface is denoted by 4).

When a dielectric filter is formed,
The outer conductors on the side surfaces of the dielectric resonator member having the above-described structure are joined to each other, and the inner conductors of the joined dielectric resonator members are capacitively coupled to each other. For example, a structure in which a dielectric substrate having a coupling capacitance component is arranged and coupled outside one end face side of a dielectric resonator, and a dielectric block is provided on a joint side surface of two dielectric resonators that are joined to each other. Are formed so that the coupling windows coincide with each other, and the inner conductors of the two dielectric resonators are coupled to each other through the coupling window.

In a method of manufacturing the dielectric resonator 10 as such a dielectric resonance member, a dielectric block prototype having a predetermined shape is formed by press-forming a predetermined dielectric material.
Thereafter, the dielectric block 1 in which the through holes are formed is formed by a sintering process. Next, the inner conductor 3 and the outer conductor 4 are formed. Thereafter, in the thick conductive film on one end face of the dielectric block 1 and the dielectric resonance member of the dielectric filter,
Unnecessary conductor films have been polished and removed from a part of the outer conductor 4 on the side surface so as to form a predetermined coupling window.

When the above-mentioned inner conductor 3 and outer conductor 4 are formed by a thick film technique, a dielectric block is immersed in a conductive paste containing silver as a main component and containing glass frit.
The centrifugal separation process is repeated, and a thick coating film having a uniform thickness is applied to the entire surface of the dielectric block, and the thick coating film is baked at 800 to 900 ° C. As a result, the entire surface of the dielectric block (including the inner wall surface of the through hole 2)
The baked thick conductor film is deposited.

As another method, when the outer conductor 4 and the inner conductor 3 are formed by plating, the entire surface of the dielectric block 1 is roughened by etching to obtain a Pd
After coating with a catalyst such as this, it was immersed in an electroless copper plating solution to plate copper to a predetermined thickness.

[0009]

FIG. 4 shows a part of the outer conductor 4 when the inner conductor 3 and the outer conductor 4 are formed by a thick film technique. The conductor serving as the outer conductor 4 contains glass frit in the conductive paste in order to achieve close contact with the dielectric block 1. For this reason, as shown in FIG. 4, in the baked outer conductor 4, the molten glass component G is attracted to the dielectric block 1 side, and strong adhesion is obtained.

However, on the other hand, a layer rich in the glass component G is formed at the interface with the outer conductor 4.
Therefore, the conductivity of the surface portion of the outer conductor 4 on the interface side of the dielectric block 1 becomes considerably lower than the conductivity of a single metal (here, silver), and as a result, the Q characteristic of the dielectric resonator deteriorates. I will.

In particular, when the flow of the high-frequency current in the outer conductor 4 and the inner conductor 3 is viewed, the flow concentrates on the surface (inner surface) of the interface with the dielectric block 1. Specifically, it flows intensively from the surface to a depth of about 2 to 3 μm (skin effect of current). In addition, the most concentrated portion of the dielectric resonator 10 having the above-described structure is the short-circuit conductor 44 portion. In particular, since the skin effect of the current cannot be sufficiently exerted at the short-circuit conductor 45, a sufficient Q value cannot be obtained. For example, a dielectric resonator having an inner conductor and an outer conductor mainly composed of silver (having an outer shape of 2 mm square and a resonance frequency of 9 mm).
At a height of 00 MHz), the Q value is theoretically about 320, but actually remains at about 200.

FIG. 5 shows a part of the outer conductor 4 when the outer conductor 4 is formed by a plating technique. In order to use this plating technique, the surface of the dielectric block 1 needs to be roughened S in order to improve the adhesion between the dielectric block 1 and the inner conductor 3 and the outer conductor 4 as described above. This requires a very large amount of time in the manufacturing process.

The current flowing through the dielectric resonator 10 is:
Since the flow concentrates on the surface of the interface between the dielectric block 1 and the inner conductor 3 and the outer conductor 45, the Q characteristic of the dielectric resonator is greatly deteriorated due to the surface roughness of the dielectric block 1. I was Moreover, the electroless copper plating itself is completely
Since it is not a dense metal of copper, the conductivity is low, and the Q value is thereby deteriorated. Specifically, only a Q value of about 180 was obtained with the above-described dielectric resonator.

The present invention has been devised in view of the above-mentioned problems, and has as its object to change the structure of an outer conductor formed on a short-circuit end face to obtain a dielectric material having a high Q value and excellent handling. A body resonance member is provided.

[0015]

According to the present invention, there is provided a columnar dielectric block having an open end face and a short-circuit end face, wherein a through-hole is formed from the open end face to the short-circuit end face, and a conductive film is formed on an inner wall surface of the through-hole. In a dielectric resonance member formed by forming an outer conductor made of a conductive film on the short-circuited end face and the side face of the dielectric block, the outer conductor of the short-circuited end face is formed on a metal thin film layer as a base layer. A dielectric resonance member formed by applying a thick metal conductor film.

[0016]

According to the present invention, an underlying metal thin film layer formed by a thin film technique is formed on the short-circuit end face of a dielectric block, and a thick metal conductor film is deposited on the thin metal underlying conductor layer.

That is, unlike the prior art, there is no need to use a plating technique, and it is not necessary to perform a roughening treatment on the surface of the dielectric block. Therefore, the dielectric block can be formed in a relatively short time in the manufacturing process.

Further, in the outer conductor (short-circuit conductor) of the short-circuit end face having a high current distribution density, the surface of the dielectric block is not roughened, and the short-circuit conductor at the interface with the dielectric block is completely Since it can be formed of a simple metal conductor, it can sufficiently respond to the skin effect of the current and increase the conductivity. Therefore, an improvement in the Q value can be achieved. In addition, since the thick metal conductor film is applied on the thin metal base conductor layer, the outer conductor has a sufficient thickness, and, for example, very stable connection can be achieved even in connection with an external circuit.

A metal such as silver is vapor-deposited on the short-circuit end of the dielectric ceramic or a thin film is formed by a sputtering method, and then a silver paste is applied by printing or dipping to form a baked electrode.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A dielectric resonance member according to the present invention will be described below with reference to the drawings.

FIG. 1 is an external perspective view of a dielectric resonator which is an example of a dielectric resonance member, FIG. 2 is a longitudinal sectional view thereof, and FIG. 3 is an enlarged sectional view illustrating the configuration of a short-circuit conductor. is there.

In the figure, 10 is a dielectric resonator, 1 is a dielectric block, 2 is a through hole, 3 is an inner conductor, and 4 is an outer conductor. In addition, among the outer conductors 4, reference numeral 40 is a short-circuit conductor formed on the short-circuit end face of the dielectric block 1.

The dielectric block 1 constituting the dielectric resonator 10 is made of a block 1 made of a substantially rectangular parallelepiped dielectric ceramic having an end face size of, for example, 2 mm × 2 mm and a length (height) of, for example, 4.6 mm. In the longitudinal direction of the dielectric block 1, a through hole 2 is formed that penetrates one end face (hereinafter, referred to as an open end face) and the other end face (hereinafter, referred to as a short-circuit end face) of the dielectric block 1. . still,
In the figure, there are two steps near the opening on the open end face side.

The opening diameter of the through hole 2 on the open end face is, for example, 1.2 mm, and the opening diameter on the short-circuit end face is, for example, 0.6 mm.
mm.

The inner wall surface of the through hole 2 of the dielectric block 1 has a thickness of about 10 μm formed by a thick film method.
(Hereinafter referred to as inner conductor 3) is formed by deposition. Outer conductors 4 are formed on five outer surfaces of the dielectric block 1 except for the open end surfaces.

The outer conductors 4 on the four side surfaces of the dielectric block 1 have a thickness of about 10 μm formed by a thick film method.
m is a conductor film containing silver as a main component. The outer conductor (especially, short-circuit conductor 40) on the short-circuit end face of the dielectric block 1 is formed from the dielectric block 1 side by a thin-film metal base conductor layer 41 having a thickness of 2 to 3 μm and a thick film formed by a thin-film technique. The conductor film has a two-layer structure of a thick metal conductor film 42 having a thickness of about 10 μm formed by the technique.

In the dielectric resonator 10 having such a structure, the open end face side of the inner conductor 2 serves as the signal side, and the signal input to the inner conductor 3 reduces the length of the dielectric resonator 10 by about 1 /. 4
It resonates at a frequency that is a wavelength, and is thus used as a resonance circuit component.

The above-described dielectric resonator 10 can also be used as a dielectric filter by capacitively joining a plurality of dielectric resonators. For example, a coupling window for capacitively coupling to one side surface (joining side surface) of two dielectric resonators joined to each other is formed, and the inner conductors of the joined dielectric resonators are connected to each other through the coupling window. Or combine them.

A characteristic of the present invention is that the outer conductor 4 at the short-circuit end face portion of the dielectric block 1 having the highest current distribution density is provided.
(Short-circuit conductor 40) has a multilayer structure.

That is, from the dielectric block 1 side, a metal thin film layer (hereinafter, referred to as a base layer) formed by a thin film technique.
This is a conductor film having a two-layer structure of a thick metal conductor film 40 having a thickness of about 10 μm formed by a thick film technique.

Therefore, due to the skin effect of the current (most of the high-frequency current flows in a range of 2 to 3 μm from the surface of the conductor), the surface of the short-circuit conductor 40 on the interface side of the dielectric block 1 where the high-frequency current easily flows is thin film metal. The base conductor layer 41 is provided. The thickness of the thin-film metal base conductor layer 41 is
It is about 0.5 to 1.0 μm. As a result, since the junction interface with the dielectric block 1 where the skin effect of the current is most remarkable can be made of a pure metal material, the conductivity of this portion can be greatly increased, and the dielectric resonator A Q factor of 10 can be greatly improved.

Further, if the thin film metal layer alone is used, the reliability of bonding to an external circuit is greatly reduced, which is not suitable for practical use. However, in the present invention, the thin film metal underlying conductor layer 41 is formed by a thick film technique. Baked thick metal conductor film 42
Are formed. As a result, the dielectric resonator is very easy to handle without any trouble even if it is connected to an external circuit.

In particular, regarding the improvement of the skin effect, in the conventional dielectric resonator (FIG. 4) in which the outer conductor is formed only of the thick metal conductor film 42 containing silver as a main component, in order to improve the adhesion, A conductor paste containing silver as a main component containing glass frit was used, and when baked, the glass components in the dielectric block 1 and the outer conductor 2 were strongly bonded to each other. Although the glass component G precipitated at the interface portion of the dielectric block 1 increased, the conductivity decreased, and the skin resistance increased. However, in the short-circuit conductor 40 having a high current distribution density of the present invention, Since the thin metal base conductor layer 41, which is a pure metal layer, is present, skin reduction in this portion is reduced.

In the conventional dielectric resonator in which the outer conductor is formed by a copper plating layer (FIG. 5), the surface of the dielectric block 1 must be roughened to improve the adhesion of the plating layer. did not become. When the skin effect is taken into consideration, the surface of the short-circuit conductor on the interface side of the dielectric block becomes uneven, which acts in a direction to lower the conductivity. Also, the plating layer cannot be made of dense copper metal,
The conductivity has been reduced. In the present invention, since the short-circuit conductor 40 of the outer conductor 4 having the highest current distribution density is composed of the thin metal base conductor layer 41 and the thick metal conductor film 42, both problems can be solved at once.

The above-described dielectric resonator 10 is formed by the following manufacturing method.

First, for example, a BaO—TiO ₂ system, Zr
O ₂ —SnO ₂ —TiO ₂ , BaO—Sm ₂ O ₃ —T
iO _{2 system, BaO-Nd 2 O 3 -TiO} 2 system or Ca
A predetermined dielectric material such as an O—TiO ₂ —SiO ₂ system is press-formed and fired to mold the dielectric block 1 in which the through holes 2 are formed as described above.

Next, a thin-film metal base conductor layer 41 is formed on the end face of the dielectric block that will be the short-circuit end face. Specifically, it is formed by a thin film technique such as sputtering.
In the sputtering apparatus, the short-circuited end face of the dielectric block is arranged toward the silver target, the inside of the apparatus is evacuated to 10 ^-5 Torr, and a heater is applied to the portion where the dielectric block is arranged using a heater.
Increase temperature to 0 ° C. And supply argon gas,
The inside of the apparatus is maintained at a vacuum of 10 ^-2 Torr, and thereafter, a charge is applied to the silver target (100 W) to perform sputtering.
The time is about one hour, and the thickness of the silver layer as the thin-film metal underlying conductor layer 41 is about 0.8 μm.

At this time, since the dielectric block 1 is not masked, the area where the silver thin-film metal base conductor layer 41 is deposited is not limited to the short-circuit end face but also to the through hole 2 near the short-circuit end face.
Of the inner wall and the side surface of the dielectric block 1,
Since the current is concentrated most on this portion centered on the short-circuit end face, there is an effect of improving the Q characteristic.

Next, a thick metal conductor film 42 is formed on the outer peripheral surface excluding the inner wall surface and the open end surface of the through hole 2 of the dielectric block 1. That is, the conductor film adhered to the inner wall surface of the through hole 2 of the dielectric block 1 becomes the inner conductor 3, and the dielectric block 1
The conductor film adhered to the outer peripheral surface of the outer conductor 4 becomes the outer conductor 4. The short-circuited end face of the dielectric block 1 has
1, a thick metal conductor film 42 is formed,
In particular, it becomes the short-circuit conductor 40.

More specifically, the dielectric block 1 on which the thin-film metal base conductor layer 41 is formed is immersed in a conductive paste containing silver as a main component and containing glass frit. Shake off and dry. This is repeated to a predetermined film thickness (2 to 3 times the skin thickness, about 6 to 10 μm), and finally baking at 900 ° C.

Thereafter, one end face of the dielectric resonator 10, which is to be an open end face, is polished to remove the thick metal conductor film 42, thereby obtaining a quarter-wavelength type dielectric resonator.

The dielectric resonator of the present invention (resonant frequency 900
(Height at which the frequency becomes MHz), a Q value of 230 is also obtained. For example, the Q value (about 200) of the conventional dielectric resonator in which the thin-film metal underlying conductor layer 41 is not formed, the outer conductor and the inner conductor The Q value of a conventional dielectric resonator formed by plating (18
(About 0), the Q value can be greatly improved.

By using such a dielectric resonance member for a dielectric filter, a dielectric filter having very small insertion loss and excellent characteristics can be obtained.

In the above embodiment, the dielectric block 1
Has a prismatic shape, but may be, for example, a columnar shape. Although the description has been made centering on the short-circuit conductor 40 formed on the short-circuit end face having the highest current density distribution, as described above, all of the outer conductors 4 or the inner conductor 3 may be formed by the thin-film metal base conductor layer 41 by the thin-film technique. Alternatively, a multilayer structure of the thick metal conductor film 42 by a thick film technique may be used. Further, the thickness of the thin-film metal underlying conductor layer 41 may be increased to a thickness of 2 to 3 μm so that the efficiency of the skin effect can be sufficiently exhibited.

In the description of the dielectric filter, a filter structure in which a plurality of dielectric resonance members are joined has been described. However, a dielectric block is formed so that a plurality of resonance units can be formed, and the dielectric block is formed. A filter configuration in which a plurality of through-holes are formed in the block and a plurality of resonating sections are integrated may be used. In this case, a multi-layer structure of the thin metal base conductor layer 41 by the thin film technique described above and the thick metal conductor film 42 by the thick film technique on the other end face where the plurality of through holes are opened may be used.

[0046]

According to the present invention, a short-circuit conductor of a dielectric resonance member having a high current density distribution has a thin-film metal base conductor layer in which an interface portion with a dielectric block through which a high-frequency current easily flows is formed by a thin-film technique. And a thick metal conductor film. For this reason, the conductivity of this portion can be greatly improved, and as a result, a dielectric resonator member having a high Q value can be obtained.

Further, since the outer conductor having a sufficient thickness is supplemented with the thin metal film by the thin film technique to provide a sufficient thickness of the outer conductor, the skin effect of the high-frequency current (flows from the surface to a surface of 2 to 3 μm from the surface). ) Can be fully demonstrated. In addition, the reliability as before can be maintained even when the connection with the external circuit is made.

Thus, a dielectric resonance member having a high Q value and excellent handling can be obtained.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a dielectric resonator that is a dielectric resonance member.

FIG. 2 is a cross-sectional view of a dielectric resonator which is a dielectric resonance member of the present invention and corresponds to a cross section taken along line XX of FIG.

FIG. 3 is a partial cross-sectional view of an outer conductor in which a circle portion in FIG. 2 is enlarged.

FIG. 4 is a partial sectional view of an outer conductor of a conventional dielectric resonator.

FIG. 5 is a partial cross-sectional view of an outer conductor of another conventional dielectric resonator.

[Explanation of symbols]

 10 Dielectric resonator 1 Dielectric block 2 Through hole 3 Inner conductor 4 Outer conductor 40 ················································ Thick metal conductor film

Claims (1)

[Claims] 1. A columnar dielectric block having an open end face and a short-circuit end face, a through-hole extending from the open end face to the short-circuit end face is formed, and an inner conductor made of a conductive film is formed on an inner wall surface of the through-hole by the dielectric. In a dielectric resonance member in which an outer conductor made of a conductive film is formed on each of a short-circuit end face and a side face of a body block, the outer conductor on the short-circuit end face is covered with a thick metal conductor film on a metal thin film layer as a base layer. A dielectric resonance member formed by wearing.