JP2001053503A - Dielectric filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate manufacture and mounting by fixing the first end edge parallel with the mounting surface of a dielectric filter of a shield member and the second end edge positioned on a side opposite to it and parallel with the mounting surface are fixed onto an open surface. SOLUTION: At fixing of a shield member 31 to a dielectric block 30, both of its end edges 31a and 31b are fixed onto the open surface 30a of the block 30 so as to be parallel with the mounting surface 30c of the block 30. The end edges 31a and 31b are respectively soldered to ground patterns 30d and 30e, provided on the surface 30a by high-temperature soldering, etc. The member 31 can cover the center part of the surface 30a without projecting to outside from the surface 30a. Since the member 31 is fixed by its two edges to obtain sufficient strength in spite of the use of thin material and the edge 31b of the member 31 is mounted without contacting with a substrate 32, handling is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter used for terminal equipment of a portable telephone.

[0002]

2. Description of the Related Art A dielectric filter of this kind, in particular, 2-3.
In a multi-stage filter used for antenna coupling parts, etc., instead of a small product of about a stage, either house the entire filter in a metal case or only the open end face of the high resonator where the electric field tends to leak out. Is often covered with a metal plate.

FIGS. 1 (A) and 1 (B) are an exploded perspective view schematically showing the structure of a conventional dielectric filter having the latter configuration, and BB when the dielectric filter is mounted on a substrate. The sectional views in the line direction are respectively shown.

In these figures, reference numeral 10 denotes a dielectric block, 11 denotes a shield plate attached to the dielectric block 10, and 12 denotes a substrate on which a dielectric filter is mounted.

The outer surface of the dielectric block 10 has an open surface 10
Except for a, the entire surface is covered with the outer conductor 10b. Resonator holes 13 to 15 whose inner surfaces are covered with inner conductors 13 a to 15 a are provided in the dielectric block 10, whereby three resonators are integrally formed.

The shield plate 11 has one edge 11
a is the surface 1 on the opposite side of the mounting surface 10c of the dielectric block 10
0d, and the other edge 11b is a free end. By soldering the free end 11b to the ground electrode on the substrate 12, the open surface 10a is covered by the shield plate 11.

As a result, it is possible to prevent energy from leaking out of the dielectric filter and adversely affecting other circuits. Further, the open surface 10a of the dielectric filter having a fine structure can be protected. In an SMD (Surface Mount Device) type filter in which the resonator holes 13 to 15 are parallel to the mounting substrate, the upper portion of the filter (the surface 10d of 2) can be connected to ground over a short distance, which allows the out-of-band attenuation of the filter to be improved, as shown in FIG.

[0008]

SUMMARY OF THE INVENTION Such a conventional SM
Since the mounting surface 10c and the free end 11b of the shield plate 11 are both mounted on the same substrate 12 in the D-type dielectric filter, the flatness of the filter bottom including the free end 11b of the shield plate 11 (coplanarity) 16) are very strict, making their manufacture and mounting very difficult. In particular, the fired dimensions of ceramic dielectrics often vary, and it is difficult to satisfy the above coplanarity 16 even if electrical performance is obtained. Also, since the free end 11b of the shield plate 11 is not fixed until it is mounted on the substrate 12, great care must be taken in handling so that the distance between the coplanarity 16 and the open surface 10a of the shield plate and the filter is not disturbed. And

Accordingly, an object of the present invention is to provide a dielectric filter including a shield member, which is very easy to manufacture and mount.

Another object of the present invention is to provide a dielectric filter which can achieve a lower profile.

[0011]

According to the present invention, there is provided a dielectric filter in which a resonator hole is provided in a dielectric block and which has a shield member for shielding an open surface of the dielectric block from the outside. The shield member has a first edge parallel to the mounting surface of the dielectric filter, and a second edge opposite to the first edge and parallel to the mounting surface. Wherein a dielectric filter is provided wherein the first and second edges are secured on an open surface.

[0012] Dielectric filters used in terminal equipment such as mobile phones are SMDs because of their small size, light weight and low cost.
The mainstream is a type in which the case is omitted and the dielectric is exposed. However, it is advantageous to cover the open surface portion of the resonator in which a large amount of electric field energy is distributed with a shield member in order to prevent the energy from jumping out and to prevent the characteristics from deteriorating. This shield member
In a conventional dielectric filter, a configuration in which the top surface is directly connected to a ground pattern of a board to be mounted is mainly used. However, as in the present invention, an edge is fixed on an open surface and the open surface is formed. If configured to cover, it is not necessary to consider coplanarity including the shield member. In addition, the height of the dielectric filter can be reduced by the thickness of the shield member. Further, since both end edges of the shield member are fixed, the distance between the shield member and the open surface of the dielectric block is firmly fixed, so that the characteristics as the dielectric filter are stabilized and the handling becomes easy. .

The shield member has third and fourth edges running in a direction substantially orthogonal to the first and second edges, and both the third and fourth edges are free ends. Is there
Alternatively, both are preferably fixed on an open surface.

[0014] The shield member may be in the form of a bridge composed of at least three planes or at least one plane.
It is also preferable that it has a bridge shape composed of two curved surfaces.

[0015] It is also preferable that the shield member has a box-like shape composed of five planes.

The shield member may be constituted by a continuous plate member, or may be constituted by a plate member having at least one cutout or through hole.

[0017]

3A and 3B are an exploded perspective view schematically showing a structure of an SMD type dielectric filter according to an embodiment of the present invention, and this dielectric filter is mounted on a substrate. It is sectional drawing in the BB line direction in the case of having done.

In these figures, 30 is a substantially rectangular parallelepiped dielectric block, 31 is a shield member attached to the dielectric block 30 so as to cover the open surface 30a of the dielectric block 30 via a space, and 32 is a dielectric member. The board | substrate on which a body filter is mounted is each shown.

The outer surface of the dielectric block 30 is
Except for a part of a, the entire surface is covered with the outer conductor 30b. Inside the dielectric block 30, the inner conductors 33a to 35a
There are provided through resonator holes 33 to 35, the inner surfaces of which are covered with, so that three resonators are integrally formed.

In this embodiment, the shield member 31 has a gutter shape (a bridge shape composed of three planes) having a U-shaped cross section formed by bending a flat metal plate by sheet metal working or drawing. ing.

The shield member 31 is attached to the dielectric block 30 by fixing both end edges 31a and 31b on the open surface 30a of the dielectric block 30 so as to be parallel to the mounting surface 30c of the dielectric block 30. Done by More specifically, the edges 31a and 31b are respectively soldered to the ground patterns 30d and 30e provided on the open surface 30a by high-temperature solder or fixed by an adhesive and then reflow soldered. You. Accordingly, the shield member 31 can cover the central portion of the open surface 30a without protruding outside from the open surface 30a, that is, without protruding in the vertical direction of the dielectric filter with respect to the substrate 32. .

In this embodiment, the shield member 31 is used.
(The edges running in a direction substantially perpendicular to the edges 31a and 31b) 31c and 31d are free ends.

As described above, in the present embodiment, since the shield member 31 is fixed on its two sides, sufficient strength can be obtained even with a thinner material than in the past. In addition, since the edge 31b of the shield member 31 is mounted without contacting the substrate 32, there is no need to consider coplanarity as in the related art, handling is easy, and soldering by reflow can be performed. Can be. Further, since the shield member 31 does not project at all in the upward direction of the dielectric filter (in the height direction from the mounting substrate 32), the height of the entire dielectric filter can be reduced.

Of course, it is possible to prevent energy from leaking out of the dielectric filter and adversely affect other circuits, and to protect the open surface 30a of the dielectric filter having a fine structure. Also, as an SMD type filter, the potential at the top of the filter, which is structurally distant from the ground pattern of the mounting substrate and easily floats from the ground potential, can be connected to the ground over a short distance. It is also possible to improve the amount.

FIGS. 4A and 4B are exploded perspective views schematically showing a structure of an SMD type dielectric filter according to another embodiment of the present invention, and a case where this dielectric filter is mounted on a substrate. It is sectional drawing of the BB line direction.

In these figures, 40 is a substantially rectangular parallelepiped dielectric block, 41 is a shield member attached to the dielectric block 40 so as to cover the open surface 40a of the dielectric block 40 through a space, and 42 is a dielectric member. The board | substrate on which a body filter is mounted is each shown.

The outer surface of the dielectric block 40 is
The entire surface is covered with the outer conductor 40b except for a part of a. Inside the dielectric block 40, inner conductors 43a to 45a are provided.
There are provided through resonator holes 43 to 45, the inner surfaces of which are covered by, and thereby three resonators are integrally formed.

In the present embodiment, the shield member 41 has a box shape composed of five flat surfaces formed by bending a flat metal plate by sheet metal working or drawing, and has a notch 41e in a part thereof. And 41f are provided.

When the shield member 41 is attached to the dielectric block 40, both end edges 41a and 41b are perpendicular to the mounting surface 40c of the dielectric block 40 so as to be parallel to the mounting surface 40c of the dielectric block 40. This is done by fixing the remaining edges 41c and 41c on the open surface 40a of the dielectric block 40 as described above. More specifically, the edges 41a, 41f are attached to the ground patterns 40d, 40e, 40f, and 49g provided on the open surface 40a.
This is done by soldering b, 41c and 41d with high-temperature solder or by reflow soldering after fixing with an adhesive. Thereby, the shield member 41 does not protrude outside from the open surface 40a,
That is, it is possible to cover the central portion of the open surface 40a without projecting the dielectric filter in the vertical direction with respect to the substrate 42.

The notches 41e and 41f extend from the open surface 40a of the dielectric block 40, and
h and 40i to pass through the conductive pattern.

As described above, in the present embodiment, since the shield member 41 is fixed on its four sides, a more sufficient strength can be obtained even with a thinner material than in the related art. Moreover,
Since the edge 41b of the shield member 41 is mounted without contacting the substrate 42, there is no need to consider coplanarity as in the related art, handling is easy, and soldering by reflow can be supported. . further,
Since the shield member 41 does not project at all above the dielectric filter (the height direction from the mounting substrate 42), the height of the entire dielectric filter can be reduced.

Of course, it is possible to prevent energy from leaking out of the dielectric filter and adversely affect other circuits, and to protect the open surface 40a of the dielectric filter having a fine structure. Also, SMD
As a (surface mount device) type filter, the potential at the top of the filter, which is structurally distant from the ground pattern of the mounting board and easily floats from the ground potential, can be connected to the ground over a short distance. It is also possible to improve the external attenuation.

FIGS. 5A and 5B are an exploded perspective view schematically showing a structure of an SMD type dielectric filter according to still another embodiment of the present invention, and each resonator of the dielectric filter is separated. It is the perspective view shown.

In these figures, reference numeral 50 denotes a substantially rectangular parallelepiped dielectric block in which a plurality of (three in this case) resonators 501 to 503 having a substantially quadrangular prism shape are fixed with their open surfaces 501a to 503a aligned. 51 is the dielectric block 5
The shield members attached to the dielectric block 50 so as to cover the open surface 50a of the “0” through a space are shown.

The outer surface of the dielectric block 50 is
a except that a part of the outer conductor 50 and a part of the bottom surface
b. Also, the entire outer surface of each of the resonators 501 to 503 is the outer conductor 501b to 503b except for a part of the open surfaces 501a to 503a, a part of the bottom surface, and windows 501c and 502c provided on surfaces that are in close contact with each other.
Covered with.

These windows 501c and 502c are for coupling the respective resonators, and the conductor is removed. Each of the resonators 501 to 503 includes an inner conductor 53a to 5
Penetration resonator holes 53 to 55 whose inner surfaces are covered with 5a are provided.

Although not shown, the input / output terminals of the dielectric filter are formed by providing a portion from which conductors are removed at the bottoms of the resonators 501 and 503 located at both ends of the dielectric block 50.

In this embodiment, the shield member 51 has a gutter shape (a bridge shape composed of three planes) having a U-shaped cross section formed by bending a flat metal plate by sheet metal working or drawing. ing.

The shield member 51 is attached to the dielectric block 50 by fixing both end edges 51a and 51b on the open surface 50a of the dielectric block 50 so as to be parallel to the mounting surface 50c of the dielectric block 50. Done by More specifically, the edges 51a and 51b are respectively soldered to the ground patterns 50d and 50e provided on the open surface 50a by high-temperature solder or fixed by an adhesive and then reflow soldered. You. Thereby, the shield member 51 can cover the central portion of the open surface 50a without protruding outside from the open surface 50a, that is, without protruding in the vertical direction of the dielectric filter with respect to the mounting board. Become.

In this embodiment, the shield member 51 is used.
(Edges running in a direction substantially perpendicular to the edges 51a and 51b) 51c and 51d are free ends.

As described above, in the present embodiment, since the shield member 51 is fixed on its two sides, sufficient strength can be obtained even with a thinner material than in the related art. Moreover, since the edge 51b of the shield member 51 is mounted without contacting the substrate on which it is mounted, there is no need to consider coplanarity as in the past, handling is easy, and soldering by reflow is also supported. can do. further,
Since the shield member 51 does not project at all in the upward direction of the dielectric filter (in the height direction from the mounting substrate), the height of the entire dielectric filter can be reduced.

Of course, it is possible to prevent energy from leaking out of the dielectric filter and adversely affect other circuits, and to protect the open surface 50a of the dielectric filter having a fine structure. Also, as an SMD type filter, the potential at the top of the filter, which is structurally distant from the ground pattern of the mounting substrate and easily floats from the ground potential, can be connected to the ground over a short distance. It is also possible to improve the amount.

In particular, in this embodiment, each of the resonators 501 to 5
03 is formed by integrally fixing independent substantially quadrangular prism-shaped dielectric blocks. Therefore, even in the case of high-mix low-volume production, there is no need to prepare a dedicated dielectric block molding die. Can respond to production.

FIGS. 6A and 6B are exploded perspective views schematically showing the structure of an SMD type dielectric filter according to still another embodiment of the present invention, and FIG. It is the perspective view shown separately.

In these figures, reference numeral 60 denotes a substantially rectangular parallelepiped dielectric block in which a plurality of (three in this case) resonators 601 to 603 each having a substantially quadrangular prism shape are fixed with their open surfaces 601a to 603a aligned. 61 is the dielectric block 6
The shield members attached to the dielectric block 60 so as to cover the open surface 60a of the “0” through a space are shown.

The outer surface of the dielectric block 60 is
Except for a part of a, the entire surface is covered with the outer conductor 60b. Also, the entire outer surfaces of the resonators 601 to 603 are covered with outer conductors 601b to 603b except for a part of the open surfaces 601a to 603a. Each resonator 601
603 are provided with through-hole resonator holes 63 to 65 whose inner surfaces are covered with inner conductors 63a to 65a.

Each resonator 6 forming the dielectric block 60
On the open surfaces 601a to 603a of 01 to 603, chip type elements 66 to 69 such as chip capacitors or chip inductors for forming steps and input / output are provided.

In the present embodiment, the shield member 61 has a gutter shape (a bridge shape composed of one curved surface) having a U-shaped cross section formed by bending a flat metal plate by sheet metal working or drawing. And notches 61e and 61f are provided in a part thereof.

The shield member 61 is attached to the dielectric block 60 by fixing both end edges 61a and 61b on the open surface 60a of the dielectric block 60 so as to be parallel to the mounting surface 60c of the dielectric block 60. Done by More specifically, the edges 61a and 61b are respectively soldered to the ground patterns 60d and 60e provided on the open surface 60a by high-temperature solder or fixed by an adhesive and then reflow soldered. You. Thereby, the shield member 61 can cover the central part of the open surface 60a without protruding outside from the open surface 60a, that is, without protruding in the vertical direction of the dielectric filter with respect to the mounting board. Become.

The notches 61e and 61f extend from the open surface 60a of the dielectric block 60, and
It is provided for passing conductive patterns and chip-type elements 66 and 69 connected to f and 60g.

In this embodiment, the shield member 61 is used.
(The edges running in a direction substantially perpendicular to the edges 61a and 61b) 61c and 61d are free ends.

As described above, in the present embodiment, since the shield member 61 is fixed on its two sides, sufficient strength can be obtained even with a thinner material than in the past. Moreover, since the edge 61b of the shield member 61 is mounted without contacting the substrate on which it is mounted, there is no need to consider coplanarity as in the past, handling is easy, and soldering by reflow is also supported. can do. further,
Since the shield member 61 does not project at all in the upward direction of the dielectric filter (in the height direction from the mounting substrate), the height of the entire dielectric filter can be reduced.

Of course, it is possible to prevent energy from leaking out of the dielectric filter and adversely affect other circuits, and to protect the open surface 60a of the dielectric filter having a fine structure. Also, as an SMD type filter, the potential at the top of the filter, which is structurally distant from the ground pattern of the mounting substrate and easily floats from the ground potential, can be connected to the ground over a short distance. It is also possible to improve the amount.

In particular, in this embodiment, each of the resonators 601 to 6
03 is formed by integrally fixing independent substantially quadrangular prism-shaped dielectric blocks. Therefore, even in the case of high-mix low-volume production, there is no need to prepare a dedicated dielectric block molding die. Can respond to production. Also, since the characteristics of the dielectric filter can be set only by the length of each resonator and the constant number of each chip-type element, a process that requires a precise system for forming a window on the side surface of the dielectric block of each resonator. Becomes unnecessary.

The combination of the dielectric block and the shield member in the present invention is not limited to the above embodiment. For example, the dielectric block shown in FIG.
Alternatively, a shield member as shown in FIG. 6 may be combined, a shield member as shown in FIG. 4 or FIG. 6 may be combined with a dielectric block as shown in FIG. 5, or a dielectric member as shown in FIG. The block may be combined with a shield member as shown in FIG. 4 or FIG.

Further, the configuration of the dielectric block is not limited to the above-described embodiment. The dielectric block is most effective in the case of a so-called block type having a through hole, but is also effective in a multilayer type, a laminated type, or an independent resonator type as long as it has an open surface.

The structure of the shield member is not limited to the embodiment described above. For example, FIG.
As shown in (D), through holes 71 are formed on the upper surface and side surfaces thereof.
1a, 712a, 713a, and 714a and the notch 7 having a shape different from that of the notch of the above-described embodiment.
11b, 712b and 714b.

By providing such a notch or a through hole, the cleaning fluid for the flux in the process of manufacturing the dielectric filter is easily discharged and easily dried. Also, if the line impedance on the board deviates from the design value due to variations in the thickness of the mounting board, trimming the filter body rather than correcting the impedance of the mounting board may make the manufacturing process easier. In such a case, in order to trim the filter after mounting, it is convenient that the shield member has a notch or a through hole.
Further, such a notch or a through hole is also very effective in a case where it is easier to obtain better electrical performance by separating a specific functional portion on the open surface of the dielectric filter main body from the metal plate. .

It is apparent that the present invention can be applied not only to a single dielectric filter but also to a duplexer. The dielectric filter can be applied to any of a band-pass filter and a band-stop filter.

The embodiments described above are merely examples of the present invention, and do not limit the present invention. The present invention can be embodied in other various modifications and alterations. Therefore, the scope of the present invention is defined only by the appended claims and their equivalents.

[0061]

As described in detail above, according to the present invention, a dielectric hole is provided in a dielectric block, and a dielectric member having a shield member for shielding an open surface of the dielectric block from the outside. A first edge parallel to the mounting surface of the dielectric filter and a second edge opposite to the first edge and parallel to the mounting surface. Since the first and second edges are fixed on the open surface, manufacture and mounting including the shield member are very easy, and further, the height is reduced. Can be.

In recent years, in SMD type dielectric filters, in many cases, the entire dielectric block is exposed without being put in a case in order to reduce the size and cost. However, when the required attenuation is large, it is necessary to connect the upper part of the dielectric block to the ground pattern of the mounting board with the shortest distance. Therefore, the open surface is covered with a shield plate as shown in FIG. Connecting has been done conventionally. Since this shield plate is required to be attached to the filter in advance, it is required that the free end of the shield plate be located exactly on the same plane as the bottom surface of the dielectric block (coplanarity). This is very difficult considering the dimensional variation of the dielectric block obtained by firing. Furthermore, if the relative position from the open surface shifts, it will affect the characteristics of the dielectric filter. Therefore, it is necessary to accurately position the shield plate when mounting it, and great care must be taken in handling after mounting. Was.

However, according to the present invention, since the edge of the shield member is fixed on the open surface of the dielectric block, there is no need to consider coplanarity. Moreover, since the shield member is fixed to the open surface of the dielectric block on at least two sides, the position of the shield member and the open surface does not change due to handling. Further, since the shield member does not protrude above the dielectric block, it can contribute to the reduction in height of the filter as described above.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view schematically showing a structure of a conventional dielectric filter, and a cross-sectional view taken along line BB when the dielectric filter is mounted on a substrate.

FIG. 2 is a characteristic diagram showing an effect of a shield plate.

FIG. 3 is an exploded perspective view schematically showing a structure of a dielectric filter according to an embodiment of the present invention, and a cross-sectional view taken along line BB when the dielectric filter is mounted on a substrate.

FIG. 4 is an exploded perspective view schematically showing a structure of a dielectric filter according to another embodiment of the present invention, and a cross-sectional view taken along the line BB when the dielectric filter is mounted on a substrate.

FIG. 5 is an exploded perspective view schematically showing a structure of a dielectric filter according to still another embodiment of the present invention, and a perspective view showing each resonator of the dielectric filter separately.

FIG. 6 is an exploded perspective view schematically showing a structure of a dielectric filter according to still another embodiment of the present invention, and a perspective view showing each resonator of the dielectric filter separately.

FIG. 7 is a perspective view showing various modifications of the structure of the shield member.

[Explanation of symbols]

30, 40, 50, 60 Dielectric block 30a, 40a, 50a, 60a, 501a, 502
a, 503a, 601a, 602a, 603a Open surface 30b, 40b, 50b, 60b, 501b, 502
b, 503b, 601b, 602b, 603b Outer conductor 30c, 40c, 50c, 60c Mounting surface 30d, 30e, 40d, 40e, 40f, 40g, 5
0d, 50e, 60d, 60e Ground pattern 31, 41, 51, 61 Shielding members 31a, 31b, 31c, 31d, 41a, 41b, 4
1c, 41d, 51a, 51b, 51c, 51d, 61
a, 61b, 61c, 61d Edge 32, 42 Substrate 33, 34, 35, 43, 44, 45, 53, 54, 5
5, 63, 64, 65 through resonator holes 33a, 34a, 35a, 43a, 44a, 45a, 5a
3a, 54a, 55a, 63a, 64a, 65a Inner conductors 40h, 40i, 60f, 60g Input / output terminals 41e, 41f, 51e, 61f, 711b, 712
b, 714b Notch 66, 67, 68, 69 Chip type element 501c, 502c Window 711a, 712a, 713a, 714a Through hole

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Koichi Ishii 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDC Corporation F-term (reference) 5E321 AA01 CC12 CC16 GG05 5J006 HA04 HA15 HA25 HA27 JA01 JA11 JA22 LA03 LA09 LA21 LA25 NA04 NB07 NC01 NC02 NC03 PA02 PA06 PA07

Claims (9)

[Claims] 1. A dielectric filter having a resonator member provided in a dielectric block and having a shield member for shielding an open surface of the dielectric block from the outside.
The shield member includes a first edge parallel to the mounting surface of the dielectric filter, and a second edge located on the opposite side of the first edge and parallel to the mounting surface. Have
A dielectric filter, wherein the first and second edges are fixed on the open surface. 2. The method according to claim 1, wherein the shield member includes the first and second shield members.
3. The device according to claim 1, further comprising third and fourth edges running in a direction substantially orthogonal to the edge of the first and second edges, wherein the third and fourth edges are both free ends. Dielectric filter. 3. The shield member according to claim 1, wherein the first and second shield members are provided.
And a third and a fourth edge running in a direction substantially perpendicular to the edge of the third surface, and both the third and fourth edges are fixed on the open surface. Item 2. The dielectric filter according to item 1. 4. The dielectric filter according to claim 1, wherein the shield member has a bridge shape composed of at least three planes. 5. The dielectric filter according to claim 1, wherein the shield member has a bridge shape including at least one curved surface. 6. The dielectric filter according to claim 1, wherein the shield member has a box shape including five planes. 7. The dielectric filter according to claim 1, wherein the shield member is formed of a continuous plate member. 8. The dielectric filter according to claim 1, wherein the shield member is formed of a plate member having at least one notch. 9. The dielectric filter according to claim 1, wherein the shield member is formed of a plate member having at least one through hole.