JPH0548402U - Dielectric filter - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] To provide a dielectric filter that can maintain stable filter characteristics at the time of design. A filter member 1 having an inner conductor 12 on an inner surface of a through hole of a dielectric block having a through hole 11 penetrating from one main surface to an opposite main surface and an outer conductor 13 on an outer peripheral surface excluding the one main surface.
Is a dielectric filter in which the substrate 2 having the capacitance means is joined, and the land electrode on the substrate 2 connected to the inner conductor 12 is completely separated by the earth electrode protruding pattern, and the earth electrode protruding pattern is further provided. The space between the case body 3 and the case body 3 is partitioned by the conductive partition plates 32b and 32c.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a dielectric filter used for a microwave band filter.

[0002]

[Prior art]

 2. Description of the Related Art Conventionally, dielectric filters are often used in devices such as personal radios and car phones that utilize microwaves because of their small size and high selectivity.

A conventional dielectric filter is a filter member using a dielectric porcelain and has a plurality of through holes penetrating one surface (open end surface) of the dielectric block and the other surface (short-circuited end surface) facing the one surface. And a conductive film (hereinafter referred to as an inner conductor) formed on the inner surface of the through hole, and a conductive film (hereinafter referred to as an outer conductor) on the outer peripheral surface of the dielectric block excluding the open end surface. Were joined together. Further, as a coupling structure of each resonator, a groove having a predetermined depth (hereinafter referred to as a coupling groove) is formed from the open end face side, or a substrate having a coupling capacitance is provided separately from the filter member, Each inner conductor of the filter member and the land electrode pattern on the substrate are connected by a wire bonding member or the like (Japanese Patent Laid-Open Nos. 61-15401, 61-192101 and 1-153703).

In FIG. 5, 50 is a filter member composed of a plurality of dielectric resonators 51a, 51b, 51c, and 55 is a substrate having a coupling capacitance component.

The filter member 50 is made up of, for example, three dielectric resonators 51a, 51b, 51c joined together. Each of the resonators 51a, 51b, 51c has a through hole 52 penetrating from the open end surface to the short circuit end surface, and an inner conductor 53 is formed on the inner wall of the through hole 52. An outer conductor 54 is formed on the outer surface except the open end surface.

At least a coupling capacitance component connected to the inner conductor 53 of the resonators 51 a, 51 b, 51 c described above is formed on the substrate 55. The coupling capacitance component is formed by the conductor patterns 56a, 56b, 56c formed on the substrate 55 and the conductor patterns 57a, 57b on the back surface of the substrate 55 shown by the dotted line in FIG.

Between the conductor patterns 56a and 56b and 56b and 56c on the front surface side of the substrate 55, there are predetermined comb-shaped intervals, and a capacitance (coupling capacitance K between the resonators) is generated between them. Capacitance (input / output capacitance Co, Cin of the resonator) between the conductor pattern 56a on the front surface side of the substrate 55, the conductor pattern 57a on the rear surface side, and between the conductor pattern 56c on the front surface side of the substrate 55 and the conductor pattern 57b on the rear surface side. Will occur.

The filter member 50 in which the three resonators 51 a, 51 b, and 51 c are bonded is bonded to the above-described substrate 55, and the inner conductors 53 of the resonators 51 a, 51 b, and 51 c and the front surface side of the substrate 55 are further bonded. The formed conductor patterns 56a, 56b, 56c were connected to each other using a conducting means 58 such as a conducting pin or a conducting wire. Further, the structure of the filter member 50 and the substrate 55 described above is covered with the case body 59 from above.

[0009]

[Problems of conventional technology]

 However, in the above-described dielectric filter, since the conductor patterns 56a, 56b, 56c are exposed on the surface, stray capacitance or the like is placed on the conductor patterns 56a, 56b, 56c, and a predetermined filter member at the time of designing. There was a change from the characteristics of. The ground electrode extends in the actual flat plate 1-153703 so as to separate the conductor patterns 56a, 56b, 56c, which are the land electrodes connected to the inner conductor 53 of the resonators 51a, 51b, 51c, but are floating. The failure due to capacity was not sufficiently prevented.

An object of the present invention was devised in view of the above-mentioned problems, and it is an object of the present invention to provide a dielectric filter capable of completely preventing a failure due to a stray capacitance which is likely to occur in a land electrode pattern.

[0011]

[Concrete means for solving the problem]

 In order to achieve the above-mentioned object of the present invention, the present invention provides a dielectric filter member having a plurality of resonance means composed of an inner conductor and an outer conductor, and a plurality of dielectric filter members which are connected to the inner conductor of the filter member on the surface. A dielectric filter in which a filter member and a substrate are covered with a case body while being joined to a substrate on which a land electrode is formed, and a plurality of earth electrode patterns are provided on the surface of the substrate, and an earth electrode pattern is provided on the surface of the substrate. A conductive partition plate was formed to divide the land electrode and connect to the case body in the ground electrode pattern.

[0012]

[Action]

 As described above, the plurality of land electrodes formed on the substrate are separated by the ground electrode pattern, and the conductive partition plate is arranged between the ground electrode pattern and the case. Since the pattern and the conductive partition plate at the ground potential are surrounded by the case body, the stray capacitance does not reach the land electrode, and the filter characteristics of the dielectric filter are stabilized.

[0013]

【Example】

 Hereinafter, the dielectric filter of the present invention will be described in detail with reference to the drawings. FIG. 1 is an exploded perspective view of a dielectric filter of the present invention, FIG. 2 is an equivalent circuit diagram, and FIGS. 3 (a) to 3 (c) are diagrams for explaining the structure of a substrate, respectively.

The dielectric filter of the present invention is a substrate having a filter member 1 formed by abutting three dielectric resonators 1a, 1b, 1c, a coupling capacitance component K, and input / output capacitance components Cin, Co. 2 and a case body 3 that covers the filter member 1 and the substrate 2 from the outside.

The dielectric resonator, for example, 1a, has a through hole 11 penetrating from one surface (surface serving as an open end surface) of the dielectric block body to the other opposing surface (surface serving as a short-circuit end surface). An inner conductor 12 is formed on the inner surface of the through hole 11. Further, the outer conductor 13 is formed on the outer peripheral surface of the dielectric block body excluding the open end surface. The outer conductor 13 where the three dielectric resonators 1a and 1b, 1b and 1c are in contact with each other is integrated with solder or a conductive adhesive to form the filter member 1.

The dielectric block body is a BaO—TiO ₂ system, a ZrO ₂ —SnO ₂ —TiO ₂ system, a BaO—Sm ₂ O ₃ —TiO ₂ system, a BaO—Nd ₂ O ₃ —TiO ₂ system or a CaO— system. It is made of TiO ₂ —SiO ₂ system ceramic with a predetermined dielectric constant and is set to a predetermined length according to the resonance frequency. The dielectric block body is formed by pressing the above-mentioned material into a predetermined shape having a through hole 11, and is further fired.

An inner conductor 12 such as silver or copper is formed on the inner wall surface of the through hole 11 of the dielectric block body, and silver, copper or the like is formed on the outer peripheral surface except the open end surface where the opening of the through hole 11 appears. Outer conductor 13 is formed. The outer conductor 13 is also formed on the short-circuited end face of the block body facing the open end face, and is electrically connected to the inner conductor 12. The inner conductor 12 and the outer conductor 13 are formed by depositing silver, copper, or the like by a method such as printing, coating, transferring, or plating, and firing.

As a result, the dielectric resonator 1a is determined by the capacitance component of the dielectric portion sandwiched between the inner conductor 12 and the outer conductor 13 and the length of the current path between the inner conductor 12 and the outer conductor 13. The inductive component constitutes the LC resonance circuit.

The substrate 2 is made of a dielectric ceramic such as alumina, and has a two-layer laminated structure. 3A is a front surface side plan view of the upper layer side substrate 2a, FIG. 3B is a top surface side plan view of the lower layer side substrate 2b, and FIG. 3C is a back surface side plan view of the lower layer side substrate 2b. As shown in FIG. 3A, three land electrodes 21a, 21b, 21c and a ground electrode pattern 22 are formed on the surface of the upper layer side substrate 2a. Further, via holes 23a, 23b, 23c having conductors on at least inner surfaces thereof are formed in the three land electrodes 21a, 21b, 21c. The ground electrode pattern 22 is provided between the land electrodes 21a, 21b, and 21c in order to prevent the interlaced capacitance (unnecessary capacitance generated between the land electrodes 21a and 21c) of the three land electrodes 21a, 21b, and 21c. The ground electrode protrusion patterns 22a, 22b, 22c, 22d are formed in a comb-teeth shape.

As shown in FIG. 3B, three conductor patterns 24a, 24b, 24c forming a capacitance component are formed on the upper surface of the lower layer substrate 2b. The conductor patterns 24a, 24b and 24c are electrically connected to the land electrodes 21a, 21b and 21c through via holes 23a, 23b and 23c, respectively.

As shown in FIG. 3C, input / output conductor patterns 25a and 25b and a ground electrode pattern 26 are formed on the back surface of the lower substrate 2b so as to correspond to the conductor patterns 24a and 24c. There is. The ground electrode pattern 26 is formed on substantially the entire back surface of the substrate 2b so as to surround the island-shaped input / output conductor patterns 25a and 25b.

The ground electrode pattern 22 formed on the surface of the substrate 2a, the ground electrode pattern 25 formed between the substrate 2a and the substrate 2b, and the ground electrode pattern 26 formed on the back surface of the substrate 2b are respectively They are connected by one or more end face through holes 27.

Next, a method of manufacturing the substrate 2 will be briefly described. First, prepare two large alumina green sheets.

Next, in the large-sized green sheet that becomes the upper substrate 2 a, break grooves are formed vertically and horizontally in order to divide each region that becomes the substrate 2. At the same time, holes to be the conductive via holes 23a, 23b, 23c are formed by punching. Here, the holes to be the via holes 23a, 23b, 23c are formed at predetermined positions where the land electrodes 21a, 21b, 21c are formed.

Next, a conductive paste containing Ag, Ag alloy, Cu, Cu alloy or the like is used to print by suction through the via holes 23a, 23b, and 23c to fill the via holes with the conductive paste. ..

Next, in the large-sized green sheet that becomes the lower substrate 2b, three conductor patterns 24a, 24b, and 24c are formed by screen printing in the region that becomes the substrate 2 using the above-mentioned conductive paste. ,dry.

The two large green sheets thus formed are aligned and integrated by thermocompression bonding. Next, in order to establish continuity between the ground electrode pattern 22 on the front surface side of the substrate 2a and the ground electrode pattern 26 on the back surface side of the substrate 2b, a hole to be the end face through hole 27 is punched so as to straddle the break groove. It is formed by processing.

Next, the green sheet, the internal conductor patterns 24a, 24b, 24c, and the ground electrode pattern 25 are integrally sintered by firing at about 900 ° C. in the atmosphere.

Next, a conductive paste containing Ag, Ag 2 alloy, Cu, Cu alloy or the like is used in each area of the surface of the sintered laminated large-sized substrate to be the substrate 2, and three land electrodes 21 a are used. , 21b and 21c and the ground electrode pattern 22 are formed by screen printing and dried. At this time, a conductor film is also printed on the inner surface of the hole to be the end surface through hole 27.

Next, using a conductive paste containing Ag, Ag alloy, Cu, Cu alloy, etc., in each region to be the substrate 2 on the back surface of the sintered large laminated substrate, the input / output conductor pattern 25a, 25b and the ground electrode pattern 26 are formed by screen printing using the above-mentioned conductive paste and dried. At this time, the conductor film is also printed on the inner surface of the hole to be the end surface through hole 27, and the inner surface of the end surface hole 27 is printed twice, and the reliability of the bonding is significantly improved.

Next, the conductor films of the land electrodes 21a, 21b, 21c, the ground electrode pattern 22, the protruding patterns 22a to 22d, the input / output conductor pattern, the ground electrode pattern 26, and the end surface through holes 27 are formed on both front and back surfaces. The formed large-sized laminated substrate is baked again, and the land electrodes 21a, 21b, 21c, the ground electrode patterns 22, 27, the input / output conductor patterns 25a, 25b, etc. are baked.

Finally, the substrate 2 is divided along the flake groove to extract a plurality of substrates 2 of a predetermined size.

In the manufacturing method described above, if the internal conductor patterns 24a, 24b, 24c are printed from the back surface side of the large green sheet on the upper layer side in which the holes to be the via holes 23a, 23b, 23c are formed, the via holes 23a, It is more preferable that the filling of 23b and 23c and the connection between the via holes 23a, 23b and 23c and the internal conductor patterns 24a, 24b and 24c can be formed by a single printing process, and the connection can be secured.

The connection between the substrate 2 and the filter member 1 thus manufactured is performed by connecting the land electrodes 21a, 21b and 21c formed on the surface of the substrate 2 and the inner conductor 12 of the three resonators 1a, 1b and 1c. .. are electrically connected to each other by wire bonding or connecting means of a separate connecting piece.

After the filter member 1 and the substrate 2 are bonded in this way, they are covered from above by the conductive case body 3.

The case body 3 is in the form of a housing having at least one opening 31 so that the filter member 1 and the substrate 2 are covered from the upper side. In FIG. 1, two surfaces, that is, a bottom surface that covers the filter member 1 and the substrate 2 and a surface that corresponds to the short-circuit end surface side of each resonator 1a, 1b, 1c are opened.

Further, a part of the side wall of the three sides corresponding to the substrate 2 is formed with bent portions 32a, 32b, 32c which are slightly bent toward the case body opening 31 side.

The case body 3 is further electrically connected to the outer conductor 13 on the upper side of the filter member 1 by a conductive paste such as solder. By joining the case bodies 3, the filter member 1 and the substrate 1 are firmly joined, and substantially the entire outer conductor 13 of the filter member 1 is grounded to the ground potential. If necessary, a plurality of outwardly bent earth terminals may be formed at the edge of the opening 31 of the case body 3.

Further, the upper surface of the case body 3 is connected to the ground electrode protruding patterns 22b and 22c for separating the case body 3 and the land electrodes 21a, 21b and 21c from each other, and the land electrodes 21a and 21b are electrically separated from each other. The sex partition plates 33a and 33b are formed. The electrically conductive partition plates 33a and 33b may have windows 34a and 34b formed on the upper surface of the case body 3, and may also serve as bent portions to form the windows 34a and 34b. In this case, it is desirable that the tip ends of the conductive partition plates 33a and 33b be bent so as to be horizontal with respect to the substrate 2 so as to be easily connected to the substrate 2. Further, it may be erected as a separate projecting piece that acts on the partition pieces 33a and 33b.

The connection between the conductive partition plates 33a, 33b and the ground electrode projecting patterns 22b, 22c on the substrate 2 is performed by preliminarily setting the conductive partition plates 33a, 33b of the case body 3 in advance. When cream solder or the like is applied onto the protruding patterns 22b and 22c to cover the filter member 1 and the substrate 2 with the case body 3, the conductive partition plates 33a and 33b and the earth electrode protruding patterns 22b and 22c are brought into contact with each other. This is achieved by melting and joining the cream solder on the ground electrode protruding patterns 22b and 22c when soldering the filter member 1 and the substrate 2 with the body 3.

Further, without using the solder paste, the conductive partition plates 33a and 33b are brought into contact with the ground electrode projecting patterns 22b and 22c on the substrate 2 and then melted through the windows 34a and 34b of the case body 3. You may join by supplying the solder.

As described above, the conductive patterns are connected to the ground electrode projecting patterns 22 b and 22 c formed on the surface of the substrate 2 so as to separate the land electrodes 21 a, 21 b and 21 c from each other, and are substantially vertically erected on the substrate 2. Since the partition plates 33a, 33b are formed, the land electrodes 21a, 21b, 21c are two-dimensionally separated into the ground electrode projecting patterns 22b, 22c, and three-dimensionally the conductive partition plates 33a, 33b and the case body. Since it is individually partitioned by 3, the stray capacitance and the like generated between the land electrodes 21a, 21b, 21c and the outside can be completely prevented. Therefore, the coupling capacitance K between the resonators 1a, 1b, and 1c is not affected by stray capacitance outside the design, and stable filter characteristics as designed can be stably maintained.

Although the structure of the substrate 2 is described as a laminated substrate having a two-layer structure, the capacitor electrode pattern is formed so that the land electrode is on the front surface of the single-layer substrate and the land electrode is on the back surface. And a ground electrode protruding pattern is formed on the surface thereof, or another substrate structure may be used. Further, although the substrate 2 has been described as the substrate arranged on the open end face side of the filter member, the size of the substrate 2 is increased to form a ground electrode having a large area, and the filter member 1 is placed on the ground electrode. It doesn't matter.

Further, as the structure of the filter member 1, the resonance means in which the three resonators are in contact with each other has been described, but the number of the resonance means is not limited to three, and the resonance means may be selected depending on the filter characteristics. The number of means can be set as appropriate, and a plurality of inner conductors are formed on a single dielectric block, and outer conductors are formed on the outer surface of a single dielectric block. It doesn't matter.

[0045]

As described above, according to the present invention, the coupling capacitance for joining the plurality of resonance means constituting the filter member is composed of the substrate separate from the filter member, and each resonance means formed on the substrate. Since the land electrode that is connected to the inner conductor is separated by the ground electrode pattern and is further separated by a conductive partition plate between the ground electrode pattern and the case body, unnecessary stray capacitance that easily gets on the land electrode Can be completely cut off, and the filter characteristics at the time of design can be maintained stably.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a dielectric filter of the present invention.

FIG. 2 is an equivalent circuit diagram of the dielectric filter of the present invention.

3A and 3B are views for explaining the structure of a substrate used in the dielectric filter of the present invention, in which FIG. 3A is a plan view of a front surface of an upper substrate, and FIG. ,
FIG. 6C is a back side plan view of the lower layer side substrate.

FIG. 4 is a cross-sectional view of the dielectric filter of the present invention seen from the open end face side.

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

FIG. 6 is a plan view of a substrate used in a conventional dielectric filter.

[Explanation of symbols]

1 --- Filter member 1a, 1b, 1c-dielectric resonator 11 --- through hole 12 --- inner conductor 13 --- Outer conductor 2 ... Substrate 21a, 21b, 21c ... Land electrode 22a, 22b, 22c, 22d ... Ground electrode protruding pattern 3 ... Case body 33a, 33b ... Conductive partition plate

Claims (1)

[Scope of utility model registration request] 1. A dielectric filter member having a plurality of resonance means composed of an inner conductor and an outer conductor, and a substrate having a plurality of land electrodes formed on its surface for connecting to each inner conductor of the filter member, and being joined together. A dielectric filter in which the filter member and the substrate are covered with a case body, wherein a ground electrode pattern is formed on the surface of the substrate so as to divide a plurality of land electrodes provided on the substrate surface, and the ground electrode is formed. A dielectric filter, wherein a conductive partition plate connected to the case body is arranged in a pattern.