JPH06303004A - Dielectric filter - Google Patents

Abstract

PURPOSE:To make a base member thin in the profile and light in the weight, to reduce the number of components, to facilitate the manufacture, to attain shielding through simple mount of a cover member, and to prevent the occurrence of problems such as exfoliation of adhesion with a built-in dielectric resonator. CONSTITUTION:The structure is adopted that a dielectric resonator is mounted on a metal-made base member 40 having a fixing thread insertion hole 42 at its both ends and a metal-made cover member 50 is used to cover the dielectric resonator for the shielding purpose. The base member is a rectangular metallic plate and a swollen step part 44 so as to be floated from a side opposite to the base is formed integrally and continuously only to parts of both long side ridges, plural claws 52 are formed to a lower end of the cover member, each claw is caulked in the step and the thickness of the claw is made thinner than the height of the step so that the folded claw is not projected from the side opposite to the base.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter mainly used in the microwave band. More specifically, a metal case that houses the dielectric resonator is used as a combination of the base member and the cover member, and bulged step portions are formed on both long side edges of the base member to crimp the claw portions of the cover member. The present invention relates to a case structure of a fixed dielectric filter. This dielectric filter is useful in fields such as various mobile communications for microwaves and satellite communications.

[0002]

2. Description of the Related Art As a dielectric filter, a quarter-wavelength resonance type dielectric coaxial resonator having a plurality of resonator holes is used and housed in a metal case having input / output pin terminals. Is conventionally known. An example thereof is shown in FIG. Here, in the dielectric resonator 10, for example, a plurality of resonator holes 14 and a plurality of connector holes 16 are alternately arranged in a longitudinal direction of a rectangular parallelepiped dielectric block 12 at specified dimensional intervals, and these are opened. One of the surfaces is an open surface, and a conductor film is formed on the outer surface excluding the open surface and the inner surface of the resonator hole to form the outer conductor 18 and the inner conductor 20, respectively. An input / output coupling capacitor 22 is attached to the open ends of the resonator holes located at both ends of the dielectric resonator 10 to form a filter body. In this type of dielectric filter, the resonance frequency of each resonator is mainly determined by the length of the resonator hole. The resonators are properly coupled by the intervening coupler holes to produce the desired filter characteristics. The coupling between the input and output and the resonator is performed by the capacitance of the capacitor 22.

The metal case that houses the dielectric resonator 10 comprises a base member 24 and a cover member 26. The base member 24 is a metal (for example, stainless steel) flat plate having a considerable thickness so as not to cause bending deformation, and has screw insertion holes 28 for fixing at both ends thereof. The dielectric resonator 10 is placed on the center of the upper surface of the base member 24 and fixed by a conductive adhesive. Further, the input / output pin terminals 30 are fixed through the base member 24 near both ends of the dielectric resonator mounting position. Input / output coupling capacitors 22 and input / output pin terminals 30 at both ends of the dielectric resonator 10.
Are connected to each other by a lead wire 32, and the dielectric resonator 10 and the upper and lower protruding portions of the input / output pin terminal 30 and the lead wire 32 are connected.
Etc. are covered with a metal cover member 26, fixed to the side surface of the base member 24 with screws 34, and shielded.

At the time of mounting, this dielectric filter is placed on a ground pattern on a printed circuit board and tightened and fixed by utilizing a screw insertion hole 28. As a result, the entire lower surface of the base member 24 is brought into surface contact with the external earth pattern for grounding. The tip of the input / output pin terminal 30 is
Insert into the input / output wiring connection land pattern formed on the printed circuit board and connect by soldering.

[0005]

With the miniaturization of wireless devices, there is a demand for further reduction in weight and thickness of dielectric filters. If the base member is thinned in order to cope with it, the mechanical strength against bending is lowered and the base member is easily bent.
If the base member bends during mounting (when the mounting screw is tightened), the adhesive layer between the dielectric resonator and the dielectric resonator that is fixed with a conductive adhesive will peel off, and the best electrical characteristics of the product will be achieved. There are drawbacks such that the characteristics cannot be expressed and the electrical characteristics vary greatly among products.

Further, the screw 34 is used to join the cover member 26 and the base member 24. Since the screw hole is formed in the base member, there is a certain limit to the thinning of the base member 24, and the base member 24 is thick. I have no choice. Moreover, because it is necessary to use a plurality of screws and form screw holes corresponding to them,
The number of parts increases, the production man-hours increase, and the production cost increases. It is possible to use a soldering method instead of the screwing method, but when joining by soldering, the internal dielectric resonator is also heated, so peeling off the joint part with the base member and performance deterioration. It may come and is not preferable.

The object of the present invention is to make the base member thinner and lighter, to reduce the number of parts and to manufacture it easily, to easily attach and shield the cover member, and to bond the built-in dielectric resonator. It is an object of the present invention to provide a dielectric filter having a structure in which problems such as peeling off do not occur.

[0008]

In the dielectric filter of the present invention, a dielectric resonator is placed and fixed on a metal base member having screw insertion holes for fixing at both ends and covered with a metal cover member. It is a shielded structure. The base member is a rectangular metal plate body, and a bulged step portion that floats from the substrate facing surface is continuously and integrally formed only on both long edge portions of the base member. A plurality of claws are formed at the lower end of the claws, and the claws are joined by caulking the claws inside the step, and the claws formed by bending the claws to be thinner than the height of the step from the substrate facing surface. It is designed so as not to project.

The bulged step portion formed on the base member is manufactured by press working or the like. It is preferable that the step portion is present in the dielectric resonator mounting range on both long edges of the base member so that both ends of the step portion serve as positioning stoppers for the claw portions of the cover member. . A plurality of claws should be provided on each side at predetermined locations (about 1
It is preferable to disperse substantially evenly (at intervals of / 2 or less).

[0010]

When the bulged step portions are continuously integrally formed on both long side edge portions of the metal base member, the mechanical strength against bending increases even if the base member is thin, and it is difficult for the base member to bend and deform. If a dielectric resonator is mounted between both steps and fixed with a conductive adhesive or the like, the base member is difficult to bend, and therefore the adhesive layer or the like may peel off even when bending stress is applied during mounting on a substrate or the like. There are few. Therefore, the simplest method of screwing can be applied to the attachment to the substrate.
Then, after the attachment, the electrical characteristics (filter characteristics) originally possessed by the dielectric filter are developed.

Since the bulged step portion is formed so as to float from the surface facing the substrate, the claw portion of the cover member can be caulked by utilizing the inside of the step portion. Since the claw portion is set to be thinner than the height of the stepped portion, the bent claw portion does not project from the substrate facing surface of the base member after the caulking (compression bonding) work, and the substrate facing surface of the base member is prevented. A good ground can be obtained by adhering to an external ground pattern.

[0012]

1 is a perspective view showing an embodiment of a dielectric filter according to the present invention with a cover member removed, FIG.
4 is a perspective view with the substrate facing surface facing upward with the cover member attached, FIG. 3 is an enlarged explanatory view of a crimping stop portion, FIG.
FIG. 4 is a sectional view showing an internal structure. The metal case that houses the dielectric resonator 10 and the like is composed of a combination of the base member 40 and the cover member 50, and has a structure in which both are joined by a caulking method to shield the inside and the outside.

The base member 40 is a rectangular, relatively thin-walled metal plate-shaped member having fixing screw insertion holes 42 at both ends. The base member 40 is much thinner than that used conventionally, and only the central portions of both long side edges thereof (only in the range where the dielectric resonator 10 is mounted, excluding the vicinity of both ends). Then, a bulged step portion 44 that floats from the substrate facing surface (lower surface in FIG. 1) is formed.
These step portions 44 can be easily manufactured by drawing or forging using a pressing machine. In the vicinity of both ends of the dielectric resonator mounting position of the base member 40, the input / output pin terminals 3
Fix 0 through. The input / output pin terminal 30 has a structure in which the center lead is surrounded by an insulating material, and is fixed to the base member 40 by a mechanical method such as press fitting or an adhesive. Then, the lead wire 32 is connected to the input / output coupling capacitor 22 of the dielectric resonator 10.

The cover member 50 is a box-shaped molded product made of a thin metal plate, and has a structure in which the claw portions 52 are integrally formed on the long sides of the opening ends. The base member 40 having the dielectric resonator 10 mounted thereon is covered with the cover member 50,
Each claw portion 52 is fixed by crimping (pressing) it in the step portion 44. At this time, the claw portions 52 located at both ends are fitted into the ends of the step portion 44, whereby positioning in the longitudinal direction at the time of mounting is performed. The thickness of each claw portion 52 (the plate thickness of the cover member 50) is smaller than the height (depth) of the stepped portion 44 formed on the base member 40, so that when the caulking is performed, the claw portion 52 is formed. No more than the surface facing the substrate. The distance between the claws arranged in parallel on one side is set to 1/2 or less of the resonance wavelength of the dielectric resonator.

Such a dielectric filter is usually screwed on a printed circuit board by using both mounting screw holes 42. At this time, the step portions 44 formed on both sides of the base member 40 firstly have a function of increasing mechanical strength against bending. If the plate thickness of the base member 40 is thin, bending deformation is likely to occur if it is a flat plate, but since the bulged step portions 44 are provided on both sides, at least the range in which the dielectric resonator in the center is mounted is deformed. Difficult (high mechanical strength) keeps flat state. Therefore, the dielectric resonator 1
There is no risk of the joint between 0 and the base member 40 peeling off. As described above, when the step portion 44 is formed only in the central portion, the bending deformation occurs at the formation start (end) end of the step portion 44. That is, the bending force is absorbed at the boundary between the portion where the step is provided and the portion where the step is not provided, and the bending stress is not applied to the central dielectric resonator 10, resulting in stable quality. A dielectric filter is obtained.

Steps 44 formed on both sides of the base member 40
Secondly, it has a function of accommodating the claw portion 52 of the cover member 50. The stepped portion 44 having the above-mentioned shape also serves as a function of positioning the cover member 50 in the longitudinal direction. Even if the base member 40 is thin, the claw portion 52 is formed by the step portion 44.
Since the thickness of the claw portion 52 can be absorbed, the claw portion 52 does not project beyond the surface facing the substrate, and there is no problem in grounding.

When the dielectric filter is screwed to the substrate,
The substrate facing surface of the base member 40 contacts the ground pattern of the printed circuit board to be grounded, and the input / output pin terminal 30
Connect to the circuit pattern. The device is incorporated in this state. In the present invention, since the adhesion and soldering between the base member and the dielectric resonator are in close contact without peeling off, the filter characteristics are not deteriorated, and the variations in the electrical characteristics of each product are also minimized. It can be suppressed.

The shape (dimension), the forming position (range), etc. of the stepped portion formed on the base member may be appropriately changed according to the shape and size of the case. Needless to say, the size and the number of claws formed on the cover member can be appropriately changed according to the bonding strength with the base member, the electrical characteristics, and the like.

[0019]

As described above, according to the present invention, since the bulged step portions are formed along both sides of the base member, the mechanical strength against bending is improved and the dielectric resonance is achieved even if the plate thickness of the base member is thin. The part of the vessel is difficult to bend, and if the fixing force is screwed using the screw insertion hole, even if the bending force is applied to the end of the base member, the force at the boundary with the step is Will be absorbed. Therefore, the adhesive or the like between the dielectric resonator and the base member is not peeled off, the filter characteristics are not deteriorated, and the variation in characteristics among products can be minimized. Therefore, that much,
The base member can be made thin, and the dielectric filter can be made thin and lightweight. Further, since the claws of the case member can be crimped and joined by utilizing the floating step, the number of parts is reduced, the assembly is facilitated, and the production man-hour is reduced. At this time,
The crimped claw portion is contained in the step portion and does not protrude from the substrate facing surface, so that no trouble occurs in grounding.

[Brief description of drawings]

FIG. 1 is a perspective view of a dielectric filter according to the present invention with a cover member removed.

FIG. 2 is a perspective view seen from the substrate facing surface direction with the cover member attached.

FIG. 3 is an enlarged perspective view of a joined portion by crimping.

FIG. 4 is a sectional view of a dielectric filter according to the present invention.

FIG. 5 is a partially cutaway perspective view showing an example of a conventional dielectric filter.

[Explanation of symbols]

 10 Dielectric Resonator 30 Input / Output Pin Terminal 40 Base Member 42 Screw Fixing Hole for Fixing 44 Step Part 50 Cover Member 52 Claw Part

Claims (3)

[Claims] 1. A dielectric filter having a structure in which a dielectric resonator is mounted and fixed on a metal base member having fixing screw insertion holes at both ends and is covered and shielded by a metal cover member. Is a rectangular metal plate, and a bulged step portion that floats from the substrate facing surface is continuously and integrally formed only on the long edge portions of both of them, and the lower end of the metal cover member A plurality of claws are formed on each of the claws, the claws are crimped and joined to the inside of the step, and the claws that are bent to be thinner than the height of the step do not protrude from the substrate facing surface. A dielectric filter characterized by the above. 2. The bulged step formed on the base member is
2. The dielectric filter according to claim 1, wherein the dielectric filter is present on both sides of the base member in a range where the dielectric resonators are mounted, and both ends of the step portion serve as positioning stoppers for the claw portions of the cover member. 3. The dielectric filter according to claim 1, wherein a plurality of claw portions of the cover member are provided on both sides at intervals of 1/2 or less of the resonance wavelength.