JPH07142906A - Cover body fitting structure for dielectric filter - Google Patents

Abstract

PURPOSE:To easily position a cover body, to easily fix it without less man-hours, to improve the reliability of fixing and to eliminate an excessive fitting space at a peripheral part. CONSTITUTION:A dielectric resonator 12 is loaded on a circuit substrate 10, and the connection circuit part 14 is formed. The metallic cover body 22 is covered and shielded so that the external surface of the dielectric resonator 12 and the ground pattern of the circuit substrate are conducted. The cover body 22 has plural projections 22a which are diffusively arranged donward at the lower end of the side board, and a projection engagement part into which the respective projections 22a can be inserted and which has a conductive film conducting with the ground pattern on a side wall surface is provided for the circuit substrate 10. The respective projections 22a are inserted into the projection engagement part and they are solder-fixed. The projection engagement part is a hole (through hole 20 and the like) or a groove. The projections can be fixed by a pressure-fitting system instead of soldering.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for mounting a metallic lid for shielding a dielectric filter. More specifically, by forming a plurality of protrusions on the lower end of the side plate of the metal lid body and inserting the protrusions into the protrusion engagement portion of the circuit board,
The present invention relates to a lid mounting structure that can be reliably and easily coupled to both a dielectric resonator and a circuit board.

[0002]

2. Description of the Related Art Various mobile communication devices such as mobile phones and car phones use various dielectric filters including a duplexer. Conventionally, as a dielectric filter, FIG.
As shown in FIG. 3, a plurality of coaxial dielectric resonators 12 are mounted on the circuit board 10, and a coupling circuit portion 14 thereof is provided to couple the dielectric resonators 12 to each other to develop desired filter characteristics. There is a structure that allows it. In such a dielectric filter, in order to prevent radio wave leakage and improve attenuation characteristics,
A metal lid 16 is placed on the top of the dielectric resonator 12
Must be electrically connected to the outer surface of the circuit board and the ground pattern of the circuit board 10.

The conventional lid 16 has a structure in which lower portions of the side plates are bent horizontally outward to form a connecting piece 16a and an elongated hole 16b is formed on the upper surface. The lid 16 is placed on the circuit board 10, the peripheral connecting pieces 16a are soldered to the surface side ground patterns 11a and 11b of the circuit board 10, and the upper surface (metallized) of each dielectric resonator 12 and the lid are covered. The body 16 and the body 16 are soldered to each other using the elongated holes 16b to be grounded. The large number of small holes 18 drawn on the circuit board 10 are through holes (a conductor layer is formed on the peripheral wall surface), and the surface side ground patterns 11a, 11 are formed.
It has a function of electrically connecting b to the ground pattern on the back surface.

[0004]

Due to such a mounting structure, the conventional lid 16 has very strict dimensional accuracy in the height direction. However, since the lid body 16 is manufactured by bending a thin metal plate, the accuracy in the height direction of the lid body is not sufficient in practice, and some variation cannot be avoided. Therefore, as shown in A of FIG. 9, when the height of the lid 16 is insufficient, the connecting piece 16a floats from the circuit board 10 to form a gap g ₁ and solder with the surface side ground pattern of the circuit board 10. It becomes difficult to attach. Conversely, B in FIG.
If the lid 16 is too high as shown in FIG.
2 is floated from the upper surface of the dielectric resonator 12 to form a gap g _{2, which} makes soldering with the upper surface of the dielectric resonator 12 difficult. Even if soldering can be performed, the metallized layer on the outer surface of the dielectric resonator 12 may be peeled off due to excessive stress due to temperature change, vibration, etc. during long-term use. Lack.

Further, in the conventional structure, the lid 16 is the circuit board 1.
Since it is free with respect to 0 and is simply placed, for example, in the soldering process by reflow, positional deviation easily occurs and workability is poor. Further, the lower side plate of the lid 16 is bent horizontally outward to form a connection piece 16a, which is brought into surface contact with the circuit board 10 for soldering. Therefore, the area is wide around the dielectric resonator 12 for connection fixing. Space is required, resulting in a large filter.

The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, to easily position the lid, to fix the lid easily with a small number of steps, and to provide a high reliability of attachment and the surrounding area. It is an object of the present invention to provide a lid mounting structure for a dielectric filter, which can reduce the size of the filter because a large mounting space is not required for the portion.

[0007]

According to the present invention, a dielectric resonator is mounted on a circuit board and a coupling circuit portion thereof is formed so as to be electrically connected to an outer surface of the dielectric resonator and a ground pattern of the circuit board. As described above, in the dielectric filter having a structure in which the lid made of metal is covered and shielded, a plurality of protrusions are distributed downward at the lower end of the side plate of the metal lid, and each protrusion can be inserted and the side wall surface can be inserted. This is a lid mounting structure for a dielectric filter in which a protrusion engagement portion having a conductor film that is electrically connected to the ground pattern is provided on the circuit board, and each protrusion is inserted into the protrusion engagement portion and fixed by soldering. Here, the projection engaging portion may be a through hole (for example, a through hole, that is, a small hole that connects the conductor patterns on the upper and lower sides of the substrate by providing a conductor layer on the peripheral wall surface).
It may be a groove formed on the side surface of the circuit board (for example, a shape obtained by cutting a through hole near the center).

Further, a plurality of protrusions dispersedly arranged at the lower end of the side plate of the metallic lid body have a bulged tip, and a protrusion engaging hole for inserting each protrusion is provided on the circuit board to make the protrusion tip end The bulging portion may be press-fitted into the protrusion engagement hole to be fixed. In that case, it is not always necessary to solder if the conduction and fixing are surely performed.

[0009]

By inserting the protrusion at the lower end of the side plate of the lid into the protrusion engaging portion of the circuit board, the lid is positioned with respect to the circuit board, and the displacement of the lid does not occur even in the soldering process.
Even if the lower edge of the lid side plate is not in contact with the circuit board, it can be fixed by using the protrusion, so that even if the height of the lid varies, the protrusion causes variation in height. Absorb. As a result, the upper portion of the lid is always in close contact with the outer surface of the dielectric resonator, and the protrusion and the protrusion engaging portion can be used for fixing to the circuit board. Since there is no horizontal outward connecting piece in the lower part of the side plate of the lid body, an extra large space for joining the lid body to the circuit board is not required.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an exploded perspective view showing an embodiment of a structure for mounting a lid of a dielectric filter according to the present invention. Here, the basic structure of the dielectric filter itself is the same as that of the conventional technique shown in FIG. The two coaxial dielectric resonators 12 are arranged side by side on the circuit board 10, and a coupling circuit pattern is provided to mount components such as a coupling capacitor to configure the coupling circuit unit 14. The coaxial dielectric resonator 12 has a structure in which a through hole is formed in a rectangular parallelepiped dielectric block, and a metallized layer is formed on the outer surface except one surface where the through hole is open and the inner surface of the through hole. Then, a part of the L-type lead terminal 13 is inserted into the through hole, and the opposite part is connected to the coupling circuit pattern. A large number of through holes (through holes in which a conductor layer is formed on the inner peripheral wall) 20 are provided in the front surface side ground patterns 11a and 11b of the circuit board 10 for electrical connection with the back surface ground pattern.

A metal lid 22 is provided on the circuit board 10 so as to cover the dielectric resonator 12 and the coupling circuit portion 14 thereof.
Install on top. The lid 22 has a structure in which one or more protrusions 22a are provided in the lower part of each side plate and an elongated hole 22b is formed in the upper surface, and is manufactured by punching and bending a thin metal plate. The protrusion 22a may have a mere straight prismatic shape. The height of the side plate is set to be less than or equal to the height of the horizontally placed dielectric resonator. In this embodiment, some of the many through holes 20 provided in the circuit board 10 are also used as the projection engaging holes. Therefore, each protrusion 22a is formed at a position corresponding to the through hole 20 serving as a protrusion engaging hole, and the through hole 22 has a size into which the protrusion 22a can be inserted.

As shown in FIG. 2, the protrusions 22a are inserted into the through holes 20 serving as protrusion engaging holes. Then, in this state, the protrusion 22a and the through hole 20 are soldered,
The lid 22 is fixed. Also, using the long hole 22b, the lid 2
2 is soldered to the dielectric resonator 12. As described above, since the side plate height of the lid body 22 is set to be equal to or lower than the height of the dielectric resonator 12 placed horizontally, if the height dimension of the lid body 22 varies a little, as shown in FIG. When the upper surface of the lid body 22 is in close contact with the upper surface of the dielectric resonator 12, the lower edge of the side plate of the lid body 22 is slightly floating (indicated by symbol f) from the upper surface of the circuit board 10. The protrusion 22a is the through hole 20.
Since it is inserted inside, the positioning is performed and the soldering can be surely performed. Since the structure is almost entirely surrounded by the metal lid and the ground pattern, even if there is a slight gap between the circuit board 10 and the lower edge of the lid side plate, almost no radio wave leakage occurs and the attenuation characteristic is reduced. It does not get worse.

FIG. 4 shows an example of a method of soldering the protrusions. 4A is an example in which the solder rings 24 are fitted into the respective protrusions 22a of the lid body 22, inserted into the through holes 20 of the circuit board 10, and soldered together through a reflow furnace. In FIG. 4B, the solder paste 26 is annularly applied around the through hole 20 serving as the projection engaging hole in the circuit board 10, and the projection 22a of the lid 22 is inserted into the through hole 20. Similarly, this is an example of collectively soldering through a reflow furnace. Of course, it is also free to solder one by one.

FIG. 5 is an exploded perspective view showing another embodiment of the present invention. Since the basic configuration is the same as that in FIG. 1, corresponding parts are designated by the same reference numerals, and description thereof will be omitted. The feature of this embodiment is that the groove 30 formed on the side surface of the circuit board 10 is used as a projection engaging portion into which the projection 22a is inserted. The groove 30 may be considered to be a through hole cut near the center thereof,
There is a conductor layer on the front surface, and thereby the front surface side ground patterns 11a and 11b of the circuit board 10 and the back surface ground patterns are electrically connected. A lid 22 is provided in each groove 30.
The projection 22a is fitted and soldered. Also in this case,
The structure may be such that a solder ring is attached or a solder paste is applied. Since this structure has a groove structure, there is an advantage that the circuit board 10 can be made smaller.

FIG. 6 shows another embodiment of the present invention. Here, in order to simplify the drawing, only the projection and the projection engagement hole are drawn. Here, the projection 32 formed on the lower end of the side plate of the metallic lid has a shape in which the tip bulges like a hook. The circuit board 10 is provided with projection engagement holes (also serving as through holes 34 here) for inserting the projections 32. Then, the protrusion 32 is pressed into the through hole 34 and fixed. The through hole 34 may be a circular hole as shown in A of FIG. 6 or an elongated hole as shown in B, depending on the shape of the protrusion 32. In this way the lid is mechanically fixed, but in practice it is desirable to solder it further.

The present invention is not limited to the dielectric filter alone,
It can also be applied when mounted on a circuit board together with other circuit blocks. An example thereof is shown in FIG. In FIG. 7, the filter section and the amplifier module 42 are provided on the circuit board 40. Here, the filter unit is the same as in FIG. A lid 22 is provided so as to cover the dielectric resonator 12 and the coupling circuit portion 14 thereof. The protrusions 22a are dispersedly arranged on the lower end of the side plate of the lid body 22, and are inserted into the through holes 42 serving as the protrusion engaging portions of the circuit board 40 and soldered. Moreover, the long hole 2 on the upper surface
2b is used to solder to the dielectric resonator 12.

Although some embodiments of the present invention have been described above, the present invention is not limited to such a configuration. The structure of the dielectric resonator, the number of installed (the number of stages), the structure of the coupling circuit unit, and the like are arbitrary. The present invention can be applied to a dielectric filter alone or can be provided on a circuit board together with other circuit modules.

[0018]

As described above, according to the present invention, since a plurality of protrusions are formed on the lower end of the side plate of the metallic lid and are inserted into the protrusion engaging portions of the circuit board, the circuit board is Since the lid is positioned, the lid is not displaced even in the soldering process. Further, even if the lower edge of the lid side plate is not in contact with the circuit board, the protrusion can be used to fix the lid, so that even if the height of the lid varies, the protrusion varies in height. Absorbs. As a result, they can be reliably and easily fixed to both the dielectric resonator and the circuit board, are strong against external stress, and improve reliability. Further, in the present invention, since the lid does not have the horizontally outward connecting piece at the lower part of the side plate, the circuit board does not need a large space for joining, and the dielectric filter can be downsized accordingly.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a lid mounting structure according to the present invention.

FIG. 2 is a partially enlarged perspective view of the protrusion and the protrusion engaging portion.

FIG. 3 is a partial cross-sectional view of the protrusion and the protrusion engaging portion.

FIG. 4 is an explanatory view showing a method of attaching a protrusion to a protrusion engaging portion.

FIG. 5 is an exploded perspective view showing another embodiment of the lid mounting structure according to the present invention.

FIG. 6 is an explanatory view showing another embodiment of a state in which the protrusion is attached to the protrusion engaging portion.

FIG. 7 is an explanatory diagram showing an application example of the present invention.

FIG. 8 is an exploded perspective view showing an example of a conventional technique.

FIG. 9 is a partial cross-sectional view of the protrusion and the protrusion engaging portion.

[Explanation of symbols]

 10 Circuit Boards 11a, 11b Surface Side Ground Pattern 12 Dielectric Resonator 14 Coupling Circuit Section 20 Through Hole 22 Lid 22a Protrusion 22b Oblong Hole

Claims (2)

[Claims] 1. A dielectric resonator is mounted on a circuit board and a coupling circuit portion thereof is formed, and a metal lid is provided so as to be electrically connected to an outer surface of the dielectric resonator and an earth pattern of the circuit board. In a dielectric filter having a structure of covering and shielding, a plurality of projections are distributed downwardly on the lower end of the side plate of the metal lid, and a conductive film which can be inserted into each projection and is electrically connected to the ground pattern on the side wall surface is provided. A lid mounting structure for a dielectric filter, characterized in that a protrusion engaging portion having the protrusion is provided on a circuit board, and each protrusion is inserted into the protrusion engaging portion and fixed by soldering. 2. A dielectric resonator is mounted on a circuit board and a coupling circuit portion thereof is formed, and a metallic lid is provided so as to be electrically connected to an outer surface of the dielectric resonator and a ground pattern of the circuit board. In a dielectric filter having a structure of covering and shielding, a plurality of protrusions having a bulge at the tip are dispersedly arranged downward at the lower end of a side plate of the metal lid, and a protrusion engaging hole for inserting each protrusion is formed in a circuit. A lid mounting structure for a dielectric filter, which is provided on a substrate, and presses each projection into a projection engagement hole to fix it.