JPH05243811A - Dielectric filter - Google Patents

Abstract

PURPOSE:To facilitate a manufacturing process, to enhance a Q value, and to decrease loss by forming a slit having no outer conductor passing through in the thickness direction, on the joining surface of a layered resonator. CONSTITUTION:Layered resonators 1a, 1b and 1c are connected through a joining end face, and a slit 11 is constituted of one recessed part (constituted by superposing recessed parts of dielectric substrates 41a, 41b) of the resonator 1a and the other recessed part of the resonator 1b. Also, a slit 12 is constituted of the other recessed part formed in the resonator 1b and one recessed part formed in the resonator 1c. Also, in this filter, by joining plural pieces of resonators in the side part end face direction, thickness of the filter can be formed very thinly, and the filter of an extremely low profile is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a triplate type dielectric filter.

[0002]

2. Description of the Related Art Conventionally, dielectric filters have been
A plurality of dielectric resonators in which a through hole is formed in a rectangular parallelepiped block made of a dielectric porcelain and a conductor film is formed on an outer peripheral surface excluding an inner surface of the through hole and one end surface having an opening of the through hole. It was joined.

Regarding the coupling between the dielectric resonators, a slit is formed on the side surfaces that are joined to each other, and the resonators are coupled by the capacitance component of the slit portion.

However, it is difficult for the above-described dielectric filter to sufficiently meet the low profile required for use in communication equipment. In addition, it is difficult to press-mold a rectangular parallelepiped dielectric block, for example, 1.5
φ0.5mm in a dielectric block measuring 15mm x 15mm
When the through hole is formed, the length becomes longer than that of the cross section, and the presence of the through hole easily damages the mold and the like, which reduces productivity such as requiring careful handling of the product. I will end up.

Further, in order to reduce the loss of the inner conductor and obtain a resonator having a high Q value, it is necessary to make the diameter of the through hole as large as possible, but the rigidity of the dielectric block is further reduced. Productivity will decrease.

Further, when slitting the sintered dielectric block, it is necessary to form slits, which causes variations in electromagnetic field coupling due to variations in processing accuracy.

The present invention has been devised in view of the above-mentioned problems, and an object thereof is to provide a low-height dielectric filter having an extremely easy manufacturing process, a high Q value, and a small loss. It is to be.

[0008]

In order to achieve the above-mentioned object of the present invention, the present invention provides a pair of rectangular dielectrics having outer conductors formed on the outer surfaces except one end surface and one main surface. What is claimed is: 1. A dielectric filter comprising a plurality of laminated resonators formed by interposing a strip-shaped conductor pattern between substrates, the side surfaces of which are joined together. It is a dielectric filter having a slit without an outer conductor.

[0009]

As described above, according to the present invention, since the dielectric substrate in which the slits are preformed by press molding is used, the press molding work of the porcelain to be the dielectric substrate is extremely easy, and the shape of the slit is Is also a constant.
Therefore, the variation of electromagnetic field coupling is reduced, and the dielectric filter has stable characteristics.

Further, since the dielectric substrates are laminated, a low-height type dielectric filter is obtained, and the design for obtaining desired characteristics is extremely dependent on the thickness of the dielectric substrate and the pattern shape of the band-shaped conductor. It becomes an easy dielectric filter.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The dielectric filter of the present invention will be described below 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 a sectional view, and FIG. 3 is an exploded perspective view of a laminated dielectric substrate that constitutes the dielectric filter.

In the figure, a dielectric filter 10 includes a filter portion including a first laminated resonator 1a, a second laminated resonator 1b, and a third laminated resonator 1a, a lower case 2, and an upper case 3. It is mainly composed of.

The three laminated resonators 1a, 1b, 1c constituting the filter unit 1 are joined to each other via the side end faces of the respective substrates, and the joined side end faces (hereinafter referred to as the joint end faces) are joined together. Are formed with slits 11 and 12 penetrating in the thickness direction of the laminated resonators 1a, 1b and 1c, respectively. Also,
Capacitance patterns 13 and 14 serving as input / output capacitance components are formed on portions of the first and third laminated resonators 1a and 1c located at both ends of the filter unit 1. The capacitance patterns 13 and 14 are composed of pad portions 13a and 14a and conductor portions 13a and 13b extending from a conductor pattern 42b, which will be described later, and the pad portions 13a and 14a and the conductor portions 13b and 14b.
A predetermined capacity will be generated between and facing.

Of the three laminated resonators 1a, 1b and 1c constituting the filter unit 1, for example, the laminated resonator 1a is used.
Is the first dielectric substrate 41a and the second dielectric substrate 41a, as shown in FIG.
And the dielectric substrate 41b are bonded to each other on one main surface. The length of the first dielectric substrate 41a and the second
The lengths of the dielectric substrates 41b are different from each other.
When a and 41b are joined to each other, the second dielectric substrate 41b extends to the one end side by Δl. This extension X
The capacitance pattern 13 is formed on the one main surface side.

The first dielectric substrate 41a and the second dielectric substrate 41b are bonded to each other on one main surface thereof by the substrate 4
Strip-shaped conductor pattern 4 extending in the longitudinal direction of 1a and 41b
2a and 42b are formed. Further, the conductor films 43a and 43b for bonding are formed on the outer peripheral portion of the one main surface, and the dielectric substrates 41a and 4b on which the conductor patterns 42a and 42b extend further.
The outer conductor 44 except one end surface (referred to as an open end surface) of 1b
a and 44b are formed. Furthermore, the dielectric substrate 41
The concave portions 45a and 45b that have entered the inside of the substrates 41a and 41b are provided on one side end surface, which is the joining end surface of the a and 41b.
Are formed. The end face facing the open end face is called a short-circuit end face, and the conductor patterns 42a and 42b and the outer conductors 44a and 44b are electrically connected on this face.

First and second dielectric substrates 41a and 41b
Is made of a dielectric ceramic for microwaves and has a rectangular shape as a whole. Specifically, the first and second dielectric substrates 41a and 41b are formed by press molding a powder material made of a dielectric ceramic material having a predetermined thickness, for example, 1.0 mm. At this time, the concave portion 45 forming the slit 11
a and 45b are formed at the same time. Then, it is formed by sintering at a predetermined temperature.

The above-mentioned conductor patterns 42a and 42b, the outer conductors 44a and 44b, the conductor films 43a and 43b for joining, and the pad portion 13a and the conductor portion 13b constituting the capacitance pattern 13 on the second dielectric substrate 41a are respectively formed. It has a three-layer structure including a thin film underlayer formed by vapor deposition of silver or copper, an intermediate layer of copper plating, and a surface layer formed by plating a bonding material from the dielectric ceramic side. These are substrates made of the above-mentioned sintered dielectric porcelain, coated with a mask of a predetermined shape, to form an underlayer by vacuum deposition, and further to form an intermediate layer by copper plating on the underlayer, Further, a surface layer is formed on the intermediate layer by plating a bonding material such as Au, Sn or Sn alloy.

The base layer serves as an adhesion layer to the dielectric substrate so that the intermediate layer and the surface layer can be formed on the upper side by plating, and the copper plating layer of the intermediate layer facilitates the passage of high frequency current, and When mounted on a printed wiring board (not shown), it is for preventing solder erosion and the like, and the surface layer is for facilitating bonding with the two dielectric substrates 41a and 41b. Is. That is, when the two dielectric substrates 41a and 41b are bonded together, heat of a predetermined temperature is applied so that the surface layer of the dielectric substrate 41a and the surface layer of the dielectric substrate 41b form a eutectic layer or the like. It is desirable to select materials that are formed and integrated.

Further, the widths of the conductor patterns 42a and 42b are determined so as to obtain predetermined characteristics, and when the conductor patterns 42a and 42b are joined to the two dielectric substrates 41a and 41b only by joining, When the bonding strength is not sufficiently obtained, the bonding conductor films 43a, 43
The width of b is important. The bonding conductor films 43a and 43b
Is for maintaining the bonding strength and for the two dielectric substrates 41a, 41
It is formed to ensure electrical connection between the outer conductors 44a and 44b formed in b and to prevent unnecessary coupling between resonators other than the slit 11.

Further, two dielectric substrates 41a and 41b are provided.
When the two main surfaces are joined together, the dielectric substrate 41
The concave portions 45a and 45b formed on the joint end surfaces of a and 41b are overlapped with each other to form one concave portion that constitutes the slit 11 penetrating in the thickness direction of the laminated resonator 1a. This recess 45a,
The length in the longitudinal direction of the laminated resonator 1a of 45b and the cut amount into the laminated resonator 1a are determined in advance by the degree of coupling between the laminated resonator 1a forming the filter unit 1 and the laminated resonator 1b joined thereto. ing. Incidentally, this recess 45
Outer conductors 44a and 44b are not formed inside a and 45b, and the dielectric ceramic is exposed.

The laminated resonator 1c has the slit 1
2 has the same structure as the above-mentioned first laminated resonator 1a, except that one of the concave portions 45a and 45b constituting the second laminated resonator is formed on the junction end face in the direction opposite to that of the laminated resonator 1a. .. Further, since the laminated resonator 1b does not require an input / output capacitance component, no capacitance pattern is formed on the extending portion X of the second dielectric substrate 42b that constitutes the second laminated resonator 1b. And the other concave portions 45a and 45b forming the slits 11 and 12 are formed in the junction end faces on both sides of the laminated resonator 1b, and have the same structure as the above-described first laminated resonator 1a. There is.

Three laminated resonators 1 having such a configuration
a, 1b, and 1c are joined via the joining end face, and one recessed portion (which is formed by overlapping the recessed portions 45a and 45b of the dielectric substrates 41a and 41b) formed in the laminated resonator 1a is laminated. The other concave portion formed in the resonator 1b constitutes the slit 11, and the laminated resonator 1
The slit 12 is formed by the other concave portion formed in b and the one concave portion formed in the laminated resonator 1c.

As a specific joining method, the joining end surfaces of the first to third laminated resonators 1a to 1c are brought into contact with each other on the lower case 2 whose surface is plated with Sn, and the heat treatment is performed in this state. By doing so, the surface layers of the conductor patterns 42a and 42b and the bonding conductor films 43a and 43b form eutectic layers and are bonded to each other. For example, the conductor pattern 42a and the bonding conductor film 43 on the first dielectric substrate 41a side.
The surface layer of a is formed by Sn plating with a thickness of 10 to 50 μm, and the conductor pattern 42 of the second dielectric substrate 41b is further formed.
b and the surface layer of the bonding conductor film 43b have a thickness of 0.1 to 0.
When formed by 5 μm Au plating, the heat treatment temperature is
Au-Sn can be applied only by applying about 280 to 300 ° C.
A eutectic layer is formed, whereby two dielectric substrates 41 are formed.
a and 41b are joined.

Further, the conductor pattern 42 on the one contact surface side
It is also possible to apply cream solder or the like to a and the conductor film 43a for joining, and to solder jointly in a reflow furnace.
Further, a resinous conductive adhesive may be used.

The lower case 2 is made of Sn-plated iron,
A rectangular flat plate portion 21 made of phosphor bronze or the like on which the three laminated resonators 1a to 1c are mounted, and a protrusion bent upward from a side portion of the flat plate portion 21 to position the laminated resonators 1a to 1c. .. and ground terminals 23, 23 extending horizontally from the side portion of the flat plate portion 21. Further, the cutout portion 2 is provided on the open end face side of the flat plate portion 21.
4, 24 are formed. Although not shown, the lower case 2 has the tips of the ground terminals 23, 23 extended to the outside and joined to the frame body. It is cut from the frame body. That is, since the plurality of lower cases 2 are integrally formed with the frame body, a plurality of dielectric filters can be assembled at once.

The upper case 3 is made of iron plated with Si,
It is made of phosphor bronze or the like, and has a box shape that covers the three laminated resonators 1a to 1c. Multilayer resonators 1a to 1c
On the side wall of the upper case 3 on the open end side of the
Notch 31 for preventing short circuit between a and 4b
And a ground terminal 32 extending in the horizontal direction is formed at the lower end of the side wall. A notch 33 into which the protruding piece 22 of the lower case 2 is inserted is formed on the side wall of the upper case 3 that comes into contact with the side end surfaces of the laminated resonators 1a to 1c.
Are formed.

The input / output terminals 4a and 4b are made of, for example, L-shaped Sn-plated iron, phosphor bronze, or the like.
The vertical surface of the letter shape is a connecting portion soldered to the pad portion 13a extending to the open end surfaces of the laminated resonators 1a and 1c, and the horizontal surface is a lead portion connecting to a printed wiring board (not shown). .. This lead portion is the ground terminal 2 described above.
It is located on the same plane as 3, 23 and 32 and is surface-mounted with the wiring formed on the printed wiring board.

In the dielectric filter 10 having the above-described structure, the three laminated resonators 1a to 1c constitute three resonant circuits, and the three resonant circuits are connected through the slits 11 and 12 by electromagnetic field coupling. , And capacity pattern 1
3 and 14, the input and output capacitors are connected to the resonance circuits located at both ends.

Next, a method of manufacturing the above dielectric filter will be described.

First, the first and second dielectric substrates 41a and 41b forming each of the laminated resonators 1a to 1c are formed.
That is, as described above, a powder material made of a dielectric material is molded into a predetermined shape and fired, and then the conductor patterns 42a and 42b, the bonding conductor films 43a and 43b, and the outer conductor 44a are formed by a thin film technique and a plating technique. , 44b and, if necessary, the capacitance patterns 13 and 14 are formed.

Next, on the flat plate portion 21 of the lower case 2, the first
Then, the main surfaces of the second dielectric substrates 41a and 41b are brought into contact with each other and heat-treated at a temperature of, for example, 280 to 300 ° to form the laminated resonators 1a to 1c. At this time, if the joint end surfaces of the laminated resonators 1a to 1c are brought into contact with each other, the filter portion 1 can be simultaneously formed on the lower case 2.

Next, the pad portions 13a and 14a of the filter portion 1 on the flat plate portion 21 of the lower case 2 are connected to the input / output terminals 4a and 4a.
b, the upper case 3 is arranged from the upper surface side of the filter section 1 via cream solder, respectively.

Next, the filter unit 1 is attached to the lower case 2 described above.
The structure in which the upper case 3 is placed and further the input / output terminals 4a and 4b are arranged is put into a reflow furnace, and the lower case 2 and the upper case 3 and the outer conductor 44 of each of the laminated resonators 1a to 1c.
a and 44b are soldered together and the capacitance pattern 1
The input / output terminals 4a are connected to the pad portions 13a and 14a of
4b is soldered.

Finally, the ground terminals 23, 2 of the lower case 2
At the tip of 3, cut from the frame body to obtain individual dielectric filters.

In the dielectric filter manufactured as described above, since a plurality of laminated resonators in which two dielectric substrates are bonded to each other at their main surfaces are bonded in the side end face direction, the thickness of the filter can be made very thin. Therefore, an extremely low-profile dielectric filter is achieved.

In order to couple the laminated resonators 1a to 1c with each other, slits 11 and 12 penetrating the upper and lower surfaces of the laminated resonators 1a to 1c in the thickness direction are formed, and the slits 11 and 12 are dielectric. Since the green sheet of the body material is processed, the processing becomes extremely easy.

Further, the outer conductor 4 of each of the laminated resonators 1a to 1c.
4a and 44b are recesses 45a in which the slits 11 and 12 are formed,
Since the outer conductors 44a and 44b are substantially covered with only a small portion of the portion 45b and its periphery formed, a dielectric filter having a high Q value and a small loss can be achieved. In particular, the material forming the conductor patterns 42a and 42b and the outer conductors 44a and 44b includes a copper underlayer and a copper-plated intermediate layer, which can significantly reduce the resistance to high-frequency current. It becomes a dielectric filter with little loss.

Further, since the joining of the two main surfaces of the two dielectric substrates 41a and 41b and the joining of the plurality of laminated resonators 1a to 1c are formed by the collective heat treatment by the reflow furnace, the manufacturing process is easy. It becomes a dielectric filter.

Next, in the above manufacturing method, the filter unit 1
Are collectively bonded and formed from the six first and second dielectric substrates 41a and 41b that form the laminated resonators 1a to 1c, so that the laminated resonators 1a to 1c are individually resonant frequencies. Becomes difficult to adjust. Therefore, it is necessary to individually adjust the resonance frequency after joining the laminated resonators 1a to 1c. Therefore, it is performed after the filter unit 1 is placed on the lower case 2. Specifically, the laminated resonator 1
A U-shaped shield metal fitting that extends over the width of b and into which the slits 11 and 12 are inserted is used. As a result, the laminated resonators 1a to 1c are electrically separated completely by the U-shaped shield fittings into which the outer conductors 44a and 44b and the slits 11 and 12 are inserted. In this state, the measurement pattern is applied to the conductor pattern 42b and the shield plate of each of the multilayer resonators 1a to 1c, and the multilayer resonators 1 are monitored while being monitored.
the outer conductor 4a formed on the upper surface of a to 1c at the ridge portion with the open end face of the outer conductor 44a or around the slits 11,
4a is removed by a laser or a lutor, and is driven to a predetermined resonance frequency. That is, the initial laminated resonator 1
The resonance frequencies of a to 1c need to be set to frequencies slightly lower than the desired resonance frequency.

In the above-described embodiment, the recesses 45a and 45b to be the slits 11 and 12 may be formed by mechanical cutting after firing the dielectric substrates 41a and 41b. Also in this case, since the substrate is ground in the thickness direction, it can be processed more quickly than the conventional cutting process of a rectangular parallelepiped dielectric block. In addition, the conductor pattern 42
a, 42b, bonding conductor films 43a, 43b, outer conductor 44
Although a and 44b are formed by a thin film technique, they may be formed by a thick film technique such as a printing method or a coating method of a conductor material, or a joining method of the first and second dielectric substrates 41a and 41b. Alternatively, a conductive adhesive such as high temperature solder may be used in addition to the formation of the eutectic layer between the outer conductors 44a and 44b.

Although the laminated resonators 1a to 1c are joined to the lower case 2 at the same time as the joined case, the laminated resonators 1a to 1c are joined to form the filter portion 1 and then the filter portion 1 is formed. It may be arranged on the lower case 2 via solder.

Further, as shown in the filter section 1 of FIG.
A part of the slits 15 and 16 formed on the joint end faces of each of the laminated resonators 1a to 1c may be extended to the open end face side of each of the laminated resonators 1a to 1c to be opened.

In each of the above embodiments, the slit 1
1 and 12 are formed by the recessed portions 45a and 45b that have entered the inside of the dielectric substrates 41a and 41b,
It may be a window-shaped slit formed by selectively removing only the outer conductors 44a and 44b with a predetermined size. When the slits are formed by removing only the outer conductors 44a and 44b, the coupling degree is adjusted by slightly removing the outer conductors on the upper and lower surfaces of the laminated resonator which are continuous with the slits in which only the outer conductors 44a and 44b are removed. You may go by

[0044]

As described above, according to the dielectric filter of the present invention, since a plurality of laminated resonators in which two dielectric substrates are bonded to each other at their principal surfaces are bonded in the side end face direction, the thickness of the filter is very thin. Since it can be formed, an extremely low-profile dielectric filter is achieved.

Further, since the slits are formed so as to connect the laminated resonators to each other in the thickness direction of the substrate, the slit processing becomes extremely easy. Furthermore, since the outer conductor of each laminated resonator is formed on the outer peripheral surface except for the slit and its surroundings, a dielectric filter having a high Q value of the filter portion and little loss can be achieved.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view taken along the line AA of FIG.

FIG. 3 is a developed perspective view of a laminated resonator of the dielectric filter of the present invention.

FIG. 4 is a perspective view of a filter portion of another dielectric filter of the present invention.

[Explanation of symbols]

 10 ... Dielectric filter 1a to 1c ... Laminated resonator 11, 12, 15, 16 ... Slit 41a ... First dielectric substrate 41b ... Second Dielectric substrate 42a, 42a ... Conductor pattern 43a, 43a ... Bonding conductor film 44a, 44a ... Outer conductor

Claims (2)

[Claims] 1. A plurality of laminated resonators, each of which has a strip-shaped conductor pattern interposed between a pair of rectangular dielectric substrates having outer conductors formed on outer surfaces except one end surface and one main surface. A dielectric filter formed by joining side surfaces, wherein a slit without an outer conductor penetrating in a thickness direction is formed on a joining surface of the laminated resonator. 2. The dielectric filter according to claim 1, wherein the slit is exposed from one end surface of the substrate.