JPH07154105A - Dielectric filter - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide a miniaturized broadband dielectric filter. [Structure] The outer conductors 1 are respectively provided in the dielectric resonators 11 and 12.
Notches 11k and 12k are provided in 1c and 12c, and interstage coupling electrodes 11f and 12f are provided therein. At this time, the electrodes 11f and 12f are connected to each conductor, for example, the outer conductor 11
c, 12c and the inner conductors 11d, 12d are not in contact with each other. The dielectric resonators 11 and 12 are bonded so that the electrodes 11f and 12f contact each other. Furthermore, the notch 11k,
Reference numeral 12k is provided on the outer surface 11l which is in contact with and orthogonal to the outer surface 11i provided with the electrodes 11f, 12f for inter-stage coupling, and the electrodes 11g, 11h for input / output coupling are provided on the remaining outer surfaces 11m, 11n. To provide. Then, the electrode 11f and the electrode 12f are joined.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter mounted on a communication device such as a mobile phone or a wireless phone.

[0002]

2. Description of the Related Art A conventional dielectric filter will be described below.

4 and 5 are a perspective view and an exploded perspective view showing a conventional dielectric filter, respectively. 4 and 5, reference numerals 1 and 2 denote dielectric resonators, and reference numerals 1a and 2a respectively denote dielectric substrates made of a dielectric material. Through holes 1b and 2b are provided in the dielectric substrates 1a and 2a, respectively. Outer conductors 1c and 2c are provided on the outer peripheral portions of the dielectric substrates 1a and 2a, respectively.
Inner conductors 1d and 2d are provided on b and 2b, respectively.

Also, the outer conductors 1c and 2c and the inner conductors 1d and 2d.
Connection conductors 1e and 2e for electrically connecting and are respectively provided on one end faces of the respective dielectric substrates 1a and 1b. Further, the electrodes 1f and 2f for interstage coupling and the electrodes 1g and 1 for input / output coupling are provided on the respective three outer surfaces of the dielectric substrates 1a and 2a so as not to come into contact with other outer conductor portions.
h, 2g, 2h are provided. Further, the electrodes 1f and 2f for interstage coupling and the outer conductors 1i and 2i are electrically and mechanically joined to each other by a conductive joining material such as cream solder to form a two-stage filter.

[0005]

However, in the above-mentioned conventional structure, the bandwidth of the filter is determined by the size of the area (coupling capacitance) of the interstage coupling conductor, and when the filter becomes smaller, the interstage coupling becomes smaller. It is difficult to realize a wideband filter because the area of the conductor for use cannot be increased, and if the area of the conductor for interstage coupling is increased, the resonance frequency of the resonator becomes high, and when the filter is constructed, the shape becomes large. There was a problem.

The present invention solves the above-mentioned problems of the prior art, and an object of the present invention is to provide a dielectric filter which is small in size, has a wide band, and is excellent in mass productivity.

[0007]

In order to achieve this object, one surface of the outer conductor which is in contact with the surface of the outer conductor provided with the inter-stage coupling electrode and which is orthogonal to the outer conductor surface is provided with the connecting electrode. The dielectric resonator with the end face on the non-contact side removed is adhered between the inter-stage coupling electrodes and the outer conductor provided with the inter-stage coupling electrode with solder or the like, and further printed with the input / output coupling electrode. The input / output line of the substrate was directly electrically and mechanically connected by soldering or the like to form a dielectric filter.

[0008]

With this configuration, input / output coupling and interstage coupling are performed by the capacitance between the inner conductor of the dielectric substrate and the input / output coupling electrode and the capacitance between the inner conductor and the interstage coupling electrode. As a result, a wide band filter can be realized without increasing the filter shape.

[0009]

1 and 2 are a perspective view and an exploded perspective view, respectively, showing a dielectric filter according to an embodiment of the present invention. In FIGS. 1 and 2, 11 and 12 are dielectric resonators, respectively. Hereinafter, the structure of the dielectric resonator will be described using the dielectric resonator 11. BaO-TiO ₂ -
_{Nd 2 O 3, BaO-TiO} 2, ZnO 2 -SnO 2 -Ti
_{O 2, BaO-Sm 2 O} 3 -TiO 2, Ln 2 O 3 -BaO-
Dielectric substrate 11 made of dielectric material such as TiO ₂ system
A through hole 11b is provided in a.

At this time, the outer shape of the dielectric substrate 11a is rectangular, and the through hole 11b is formed to have a cylindrical cross section.
An outer conductor 11c is provided on the outer surface of the dielectric substrate 11a, and an inner conductor 11 is provided on the inner surface of the through hole 11b.
d is provided. The outer conductor 11c and the inner conductor 11d are connected by a connecting conductor 11e provided on one end surface. Further, among the four outer surfaces of the dielectric substrate 11a, a cutout portion 11k is provided on the outer surface 11i side on the open end 11j side so that the dielectric substrate 11a is exposed.

Further, an electrode 11f for interstage coupling is provided on the open end 11j side of the outer surface 11l which is in contact with the outer surface 11i and is orthogonal to the outer surface 11i, and the electrode 11f is in contact with the outer conductor 11c. It is provided in the notch groove portion 11o provided on the outer surface 11l so as not to do so.

Further, the open ends 1 of the outer side surfaces 11m and 11n.
Input / output coupling electrodes 11g and 11h are provided on the 1j side and across the respective surfaces.
g and 11h are outer surfaces 1 so as not to contact the outer conductor 11c.
It is provided in a notched groove portion 11p provided over 1m and 11n.

The dielectric resonator 12 also has substantially the same structure as the dielectric resonator 11. That is, the dielectric substrate 12a,
Through hole 12b, outer conductor 12c, inner conductor 12d, connecting conductor 12e, interstage coupling electrode 12f, input / output coupling electrodes 12g, 12h, outer side surfaces 12i, 12l, 12m, 12
n, open end 12j, notch 12k, notch groove 12o, 1
It is composed of 2p. The portions of the dielectric resonator 11 and the dielectric resonator 12 corresponding to the alphabet (for example, the dielectric base body 11a and the dielectric base body 12a) have substantially the same configuration. The reason why they are described as substantially the same is that, as can be seen from FIG. 2, the dielectric resonator 11 and the dielectric resonator 12 are mirror-symmetrical to each other. Therefore, the formation positions of the electrodes 11f, 11g, 11h and the electrodes 12f,
It is necessary to pay attention to the formation positions of 12g and 12h.

When the dielectric resonator 11 and the dielectric resonator 12 are butted so that the inter-stage coupling electrode 11f and the electrode 12f face each other and are joined together by cream solder or the like, the electrodes 11g, 11h and the electrode 12g, 12h face the same plane.

As described above, this is the dielectric resonator 1
This is because 1 and 12 are mirror-symmetrical to each other.

The outer conductors 11c and 12c, the inner conductor 11
d, 12d, connecting conductors 11e, 12e electrodes 11f, 12
Each of f, electrodes 11g, 11h, 12f, 12g, and the like (hereinafter, these films are collectively referred to as a conductor film) is composed of a thin film made of a conductive material such as copper or silver, and has a film thickness of 5 μm. It is formed to a certain extent. In this embodiment,
Although the conductor film is composed of one layer, it may be composed of two or more layers. Further, the film thickness is set to about 5 μm, but the film thickness must be appropriately determined according to the use conditions of the filter and the like.

FIG. 3 shows a cutout portion 11 according to an embodiment of the present invention.
6 is a graph showing the relationship with the inter-stage coupling degree K depending on the size of the area S of k and 12k (area shown by Z1 × Z2 in the figure).

As can be seen from FIG. 3, notches 11k and 12k
The larger the area S of, the larger the inter-stage coupling degree K becomes.
Further, the degree of inter-stage coupling K can be increased as compared with the conventional example, and a wide band filter can be constructed.

A method of manufacturing the dielectric filter having the above structure will be described below. First, the raw materials (Ba
O, TiO ₂ , Nd ₂ O _{3 and the} like) are mixed in a predetermined amount, and the mixture is mixed using a mill or the like. Next, this mixture is granulated by adjusting the particle size and adding a binder using a spray dryer or the like. Next, the granulated product is molded into a predetermined shape by using a dry press, and the molded product is heated in a baking furnace at 130 ° C.
Sintering is performed at a temperature of 0 ° C. to 1400 ° C. to produce a cylindrical dielectric substrate 11a. Next, a conductor film is formed on the dielectric substrate 11a. First, there are various forming methods for forming a conductor film, and therefore several examples will be described.

First, as a first method, the case where copper is used as the material forming the conductor film will be described. Dielectric substrate 11
The surface of a is roughened by a barrel polisher or a blasting device, and then the dielectric substrate 11a is subjected to etching treatment to adjust the surface roughness of the dielectric substrate 11a to about 5 μm to 9 μm. At this time, as the etching liquid, for example, HF-
HNO ₂ type is used. Next, after sensitizing the entire surface of the dielectric substrate 11a with stannous chloride or the like, palladium serving as a catalytic metal is attached to the entire surface to form a resist film on a part of the dielectric substrate 11a. To do.

That is, the portion of the dielectric substrate 11a to which the conductor film should not adhere (notch portion 11k, notch groove portion 1 in the future).
1o, a resist film is formed in the cut groove portion 11p). The resist film is formed by applying a resist ink on the dielectric substrate 11a by using a printing technique, a transfer technique or the like, and drying and curing the applied resist ink. Then, a thin first copper film is formed on the dielectric substrate 11a thus processed by electroless copper plating. At this time, the first copper film is selectively formed only in the portion where the resist film is not formed.

Next, a second layer is formed on the first copper film by electrolytic copper plating.
A copper film is laminated to form a conductor film. At this time, the conductor film is 5
It is formed to have a thickness of about μm. Finally, the resist film is dissolved with a solvent or the like to form an electrode. In this manufacturing method, the resist film is formed by printing the resist ink on a predetermined position of the dielectric substrate 11a by printing and then drying and curing, but there is also a method of using a photosensitive resist as the resist. That is, after a catalytic metal such as palladium is attached to the dielectric substrate 11a, a photosensitive resist is applied to the entire surface of the dielectric substrate 11a and exposed to cure only a predetermined portion of the photosensitive resist. Then, the portion where the photosensitive resist is not cured is washed away with the developer to form a predetermined electrode.

As another method, the Ag paste is applied on the entire surface of the dielectric substrate 11a by printing or dipping, dried and then heat-treated at a temperature of 800 ° C. to 900 ° C. to form a dielectric film on the conductor film. It may be formed on the entire surface of the base 11a. Further, after forming the conductor film on the entire surface, an unnecessary portion of the conductor film may be removed using an etching technique such as chemical etching or dry etching to form a predetermined electrode.

As another method, after forming a conductor film on the entire surface of the dielectric substrate 11a, cutting, laser processing, etc. are performed and physically removed to form a predetermined electrode.

The dielectric resonator 11 and the dielectric resonator 12 configured as described above are butted so that the electrodes 11f and 12f face each other, and the outer conductor 11c and the outer conductor 12c are joined by cream solder or the like. The electrode 11f and the electrode 12f are bonded to each other with a bonding material such as cream solder.

In this embodiment, the cutouts 11k and 12k are provided.
Although not shown in FIG. 1, the cutouts 11k and 12 are provided.
k may be formed so as to reach at least the open end m.
Further, in the present embodiment, the notch portions 11k and 12k are provided in the dielectric resonators 11 and 12, respectively, but they may be provided in at least one of the dielectric resonators.

[0027]

As described above, according to the present invention, one surface of the outer conductor which is in contact with the surface of the outer conductor provided with the inter-stage coupling electrode and which is perpendicular to the outer conductor surface, and which is the end surface on the side not in contact with the connecting conductor. In the dielectric resonator from which the above is deleted, at least two electrodes for inter-stage coupling are arranged so that the conductors are in close contact with each other, and the electrodes are electrically and mechanically connected by soldering, and the electrodes for input / output coupling are further connected. A small wide band filter can be realized by connecting the input / output line on the printed circuit board with solder etc., and by using the capacitance between these electrodes, the interstage coupling and the input / output coupling are made to constitute the dielectric filter. , The performance can be improved.

[Brief description of drawings]

FIG. 1 is an overall perspective view of a dielectric filter according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a dielectric filter according to an embodiment of the present invention.

FIG. 3 is a graph showing the relationship between the area S of the cutout portion and the inter-stage coupling degree K in one embodiment of the present invention.

FIG. 4 is a perspective view showing a conventional dielectric filter.

FIG. 5 is an exploded perspective view showing a conventional dielectric filter.

[Explanation of symbols]

11, 12 Dielectric resonator 11a, 12a Dielectric substrate 11b, 12b Through hole 11c, 12c Outer conductor 11d, 12d Inner conductor 11e, 12e Connecting conductor 11f, 11g, 11h, 12f, 12g, 12h Electrode 11i, 11l, 11m , 11n, 12i, 12l, 1
2m, 12n Outer side surface 11j, 12j Open end 11k, 12k Cutout 11o, 11p, 12o, 12p Cutout groove

Claims (5)

[Claims] 1. A cylindrical dielectric substrate, an outer conductor provided on an outer surface of the dielectric substrate, an inner conductor provided on an inner surface of the dielectric substrate, and one of the dielectric substrate. A connecting conductor provided on an end face for connecting the outer conductor and the inner conductor; an interstage coupling electrode provided on the outer face and not electrically contacting each conductor; and an open end side of the outer conductor. A dielectric filter comprising a plurality of dielectric resonators each having a notch reaching the open end, and the plurality of dielectric resonators being bonded so that the inter-stage coupling electrodes are bonded to each other. 2. The dielectric filter according to claim 1, wherein at least two of the plurality of dielectric resonators are provided with input / output coupling electrodes so as not to contact the outer conductor. 3. The dielectric filter according to claim 1, wherein in each dielectric resonator, the outer conductor surface is electrically or mechanically fixed by solder or a conductive adhesive. . 4. A cylindrical dielectric substrate, an outer conductor provided on an outer surface of the dielectric substrate, an inner conductor provided on an inner surface of the dielectric substrate, and one of the dielectric substrate. A connecting conductor provided on an end surface for connecting the outer conductor and the inner conductor, a first notch provided on the outer surface and having a part of the outer conductor removed, and the first notch in the first notch. An inter-stage coupling electrode that does not make electrical contact with each conductor; a second cutout portion that is provided on the outer surface and has a part of the outer conductor removed so as not to connect with the first cutout portion; A pair of dielectric resonators each having an input / output electrode provided in the second cutout portion are provided, and the open end side of the outer conductor is removed from at least one of the pair of dielectric resonators to open the dielectric resonators. An electrode for interstage coupling of each of the pair of dielectric resonators is provided with a third notch reaching the end. Dielectric filter, characterized in that the joined. 5. A cylindrical dielectric substrate, an outer conductor provided on an outer surface of the dielectric substrate, an inner conductor provided on an inner surface of the dielectric substrate, and one of the dielectric substrate. A connecting conductor provided on an end surface for connecting the outer conductor and the inner conductor, a first notch provided on the outer surface and having a part of the outer conductor removed, and the first notch in the first notch. A dielectric filter in which a pair of dielectric resonators provided with electrodes for interstage coupling that are not in electrical contact with each conductor is provided, and electrodes for interstage coupling of the pair of dielectric resonators are joined, A dielectric filter comprising: a second cutout formed by removing an outer conductor so as to reach an open end across a pair of dielectric resonators.