JPH08148875A - Circuit board shield device - Google Patents

Abstract

PURPOSE: To manufacture a circuit board shield device into one of a structure, wherein an electromagnetic shielding for a circuit component mounting part, which is formed of the child board in a combination of two circuit boards used as a child board and a parent board, is done very favorably and radiation interference to the other parent board due to the child board can be fully inhibited. CONSTITUTION: A circuit board shielding device is provided with a shielding case member 13, which is housed with the whole first printed-wiring board 11 and is electrically connected with a grounding conductor part of the board 11, and an auxiliary shielding member 14, which is provided on a second printed- wiring board 12 having a connector part 28, which is coupled with a connector part of the board 11, and is brought into contact by the member 13 and is electrically connected with the member 13 when the connector part is coupled with the connector part 28. Moreover, the member 13 is electrically connected with a grounding conductor part 27 of the board 12 through the grounding conductor part of the board 11, the connector part 28 coupled with the connector part of the board 11 and the like and moreover, through the member 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield device for a circuit board, which is provided for a circuit component mounting portion of a circuit board such as a printed wiring board and is intended to suppress radiation interference to other parts.

[0002]

2. Description of the Related Art In circuit boards such as printed wiring boards used in various electronic devices, various circuit components are attached to form circuit component mounting portions of various scales. Among such circuit component mounting parts, those including circuit components forming an oscillation circuit for generating a signal having a relatively high frequency, circuits forming a digital processing circuit for handling a pulse signal having a relatively high frequency In many cases, components and the like are provided with a shield device that applies an electromagnetic shield to unwanted signals radiated from them to prevent them from interfering with each other, that is, radiation interference.

Such a shield device is usually constituted by a conductive member attached to a circuit board so as to cover a circuit component mounting portion to be provided with an electromagnetic shield formed on the circuit board. The conductive member that constitutes the shield device is electrically connected to the grounding conductor portion on the circuit board, and is given the same potential as the grounding conductor portion.

The circuit board forming the circuit component mounting portion in which the shield device is provided is assumed to take various forms. One of them is commonly called a "slave board" and a "parent board". There is a combination of a circuit board having a relatively small scale and a circuit board having a relatively large scale, which are respectively called. When such a combination of the child board and the parent board is adopted, each of the child board and the parent board is provided with a signal path forming section and a grounding conductor section, and further, the signal path forming section and the grounding section are provided. And a connector section electrically connected to the conductor section for use, the connector section provided on the child board is connected to the connector section provided on the mother board, and a signal path is formed on the child board. The section and the grounding conductor section are electrically connected to the signal path forming section and the grounding conductor section on the parent board through the connector sections of both the daughter board and the parent board, respectively.

Then, a predetermined circuit component mounting portion formed on the child board, a predetermined circuit component mounting portion formed on the mother board,
Alternatively, both of them are provided with the shield device. At that time, the conductive member attached to the sub-board to configure the shield device is electrically connected to the ground conductor portion in the sub-board, and the conductive member attached to the main substrate to form the shield device, Electrical connection is made with the grounding conductor portion of the parent board.

FIG. 4 shows a state in which a conventionally proposed shield device is provided for a circuit component mounting portion formed on a child board in a combination of the child board and the parent board.
In FIG. 4, the main board 1 is provided with a connector section 2 that is electrically connected to a signal path forming section and a grounding conductor section (not shown) provided on the parent board 1.
Further, the child board 3 is provided with a connector portion 4 electrically connected to a signal path forming portion and a grounding conductor portion (not shown) provided therein, and the connector portion 2 and the connector are provided. The parts 4 are intended to be interconnected.

The child board 3 is provided with a shield device 5 for the circuit component mounting portion formed on the child board 3. The shield device 5 is configured by a conductive member attached to one of the facing surfaces of the child board 3 so as to cover the circuit component attached thereto. The conductive member including the shield device 5 is attached to the child board 3. Electrical connection is made with the grounding conductor portion provided. Then, the child board 3 provided with the shield device 5 is attached to the parent board 1 by connecting the connector section 4 provided to the child board 3 to the connector section 2 provided to the parent board 1.

[0008]

In the combination of the child board and the parent board as described above, each of the child board and the parent board is supposed to have a grounding conductor portion. It is the grounding conductor part in the parent board that is directly electrically connected to, and the grounding conductor part in the daughter board is through the connector part of the child board and the connector part of the parent board that are interconnected, It is electrically connected to the grounding conductor portion on the mother board. Therefore, for example, when the conventional shield device shown in FIG. 4 is provided to the circuit component mounting portion formed on the child board, it is attached to one of the facing surface portions of the child board to form the shield device. ,
The electrically conductive member electrically connected to the grounding conductor portion provided on the child board, the connector portion of the child board and the connector portion of the parent board interconnected, further, via the grounding conductor portion of the parent board, Electrical connection to the ground potential point is indirectly made.

Therefore, the impedance between the conductive member which is attached to the child board and constitutes the shield device and the ground potential point has a substantially non-negligible value. There is a possibility that a potential substantially equal to the ground potential may not be applied. If a potential substantially equal to the ground potential is no longer applied to the conductive member that constitutes the shield device, the role of the electromagnetic shield for the circuit component mounting portion formed on the sub-board, which the shield device should play, cannot be properly fulfilled. As a result, it is possible that the radiation interference to the other due to the circuit component mounting portion formed on the sub-board cannot be sufficiently suppressed, and further, depending on the situation, the conductive member forming the shield device acts as an antenna. However, radiation interference to the other by the circuit component mounting portion formed on the child board is also promoted.

In view of the above point, the present invention provides a circuit component formed on the first circuit board which is a child board in the combination of the first circuit board and the second circuit board which are the child board and the parent board. The electromagnetic shield for the circuit component mounting portion of the first circuit board is excellently provided under the provision of the mounting portion, so that the circuit component mounting portion of the first circuit board radiates other radiation. An object of the present invention is to provide a circuit board shield device capable of sufficiently suppressing interference.

[0011]

In order to achieve the above object, a shield device for a circuit board according to the present invention includes a shield case member substantially accommodating the entire first circuit board and an auxiliary shield member. And a first case in which the shield case member is provided on the first circuit board and is electrically connected to the first signal path forming section and the first grounding conductor section of the first circuit board. Has a connector opening facing the outside and is electrically connected to the first grounding conductor, and the auxiliary shield member is connected to the first connector. A second signal path forming section and a second signal path forming section in which the first signal path forming section and the first grounding conductor section are electrically connected through the first and second connector sections, respectively. Second circuit board having second grounding conductor portion Is provided and electrically connected to the second grounding conductor portion, and when the first connector portion is coupled to the second connector portion, the shield case member is in contact with and electrically connected. It is supposed to be.

[0012]

The shield device for a circuit board according to the present invention constructed as described above is used, for example, when the first circuit board is the child board and the second circuit board is the parent board. To be The first circuit board provided on the first circuit board
Is connected to the second connector portion provided on the second circuit board, and thus the child board is attached to the parent board, A shield case member that substantially accommodates the whole is provided on the second circuit board via the first grounding conductor portion provided on the first circuit board and the interconnected first and second connectors. Electrically connected to the second grounding conductor part provided, and in addition to that, a second circuit board directly provided on the second circuit board through an auxiliary shield member provided on the second circuit board.
Is electrically connected to the grounding conductor part.

[0013] As a result, the second grounding conductor portion provided on the second circuit board, which serves as the parent board, is directly electrically connected to the ground potential point. The case member includes a first grounding conductor portion provided on the first circuit board, first and second connector portions interconnected to each other, and a second grounding conductor portion provided on the second circuit board. Is electrically connected to the indirect ground potential point via the auxiliary shield member and the second grounding conductor portion provided on the second circuit board. Connection is made.

Therefore, the impedance between the shield case member and the ground potential point is substantially negligible, and a potential substantially equal to the ground potential is applied to the shield case member. Moreover, the shield case member substantially contains the entire first circuit board. Therefore, the electromagnetic shielding of the circuit component mounting portion formed on the first circuit board by the shield case member is performed extremely well, and as a result, the circuit component mounting portion formed on the first circuit board, which is the sub-board, is formed. Radiation interference to the other due to is sufficiently suppressed.

[0015]

1 and 2 show a shield device for a circuit board according to the present invention together with a circuit board to which it is applied.

In the example shown in FIGS. 1 and 2, a first printed wiring board 11 (FIG. 3) which is a child board and a parent board to which the first printed wiring board 11 is attached are used as circuit boards. It is used in combination with the second printed wiring board 12 to form a shield device for the circuit component mounting portion formed by the first printed wiring board 11. Then, in the example shown in FIGS. 1 and 2, the shield case member 13 substantially accommodating the entire first printed wiring board 11 and the first printed wiring board 11 are mounted. The auxiliary shield member 14 provided on the second printed wiring board 12 is a constituent element.

As shown in detail after being disassembled in FIG. 3, the shield case member 13 is formed of a thin plate-shaped conductive material, and has a sealed type in which the first printed wiring board 11 is built. . The first printed wiring board 11 is provided with a large number of circuit components 15 including circuit components forming a digital processing circuit that handles a pulse signal having a relatively high frequency, and forms a signal path electrically connected to them. The portion 16 and the grounding conductor portion 17 are provided. Then, the first printed wiring board 11 is provided with a connector portion 18 that is electrically connected to the signal path forming portion 16 and the grounding conductor portion 17.

The shield case member 13 supports the first printed wiring board 11 in a state of substantially surrounding the peripheral end surface portion 11A of the first printed wiring board 11, and the frame-shaped portion 20 and the frame. A first lid-shaped portion 21 that engages with the groove-shaped portion 20 and covers one of the mutually facing surfaces of the first printed wiring board 11 on which a large number of circuit components 15 are arranged; A second lid that engages with the portion 20 and covers one of the mutually opposing surfaces of the first printed wiring board 11 where the main signal path forming portion 16 and the grounding conductor portion 17 are arranged. The first lid-shaped portion 21 and the second lid-shaped portion 22 are opposed to each other by engaging with the frame-shaped portion 20 with the frame-shaped portion 20 sandwiched therebetween.

The frame-shaped portion 20 includes a plurality of second lid-shaped portions 22.
The connection protrusions 20 </ b> A protruding to the side are provided, and these are connected to the grounding conductor portion 1 of the first printed wiring board 11.
7 are soldered to a plurality of grounding conductor connecting portions 19 partially provided on the conductor 7. Thereby, the frame-shaped portion 20 is electrically connected to the grounding conductor portion 17 of the first printed wiring board 11.

Further, the frame-shaped portion 20 is provided with a cutout portion 20B, and the cutout portion 20B is through which the first printed wiring board 11 supported by the frame-shaped portion 20 is provided.
The connector portion 18 provided in the
It is supposed to form a connector opening that faces the outside of the connector.

On the other hand, the second printed wiring board 12 provided with the auxiliary shield member 14 is mounted with various circuit components 25, and the signal path forming portion 26 and the grounding conductor portion 27 to which they are electrically connected. Is said to have been provided. The second printed wiring board 12 is provided with connector portions 28 and 29 that are electrically connected to the signal path forming portion 26 and the ground conductor portion 27, and the connector portion 28 is the first The connector portion 18 provided on the printed wiring board 11 is connected. Under the condition that the connector portion 18 provided on the first printed wiring board 11 is connected to the connector portion 28, the signal path forming portion 16 of the first printed wiring board 11 is interconnected to the connector portions 18 and 28. Is electrically connected to the signal path forming portion 26 of the second printed wiring board 12 via, and the grounding conductor portion 17 of the first printed wiring board 11 connects the interconnected connector portions 18 and 28 to each other. The second printed wiring board 12 is electrically connected to the grounding conductor portion 27 via the via.

The auxiliary shield member 14 is formed of a thin plate conductive material and substantially surrounds the connector portion 28 provided on the second printed wiring board 12.
It is attached to the second printed wiring board 12 and is electrically connected to the grounding conductor portion 27 of the second printed wiring board 12. The auxiliary shield member 14 has a plurality of contact engagement pieces 1 protruding inward.
4A is provided, these contact engagement pieces 14A,
When the first printed wiring board 11 housed in the shield case member 13 is attached to the second printed wiring board 12, the first lid-shaped portion 21 and the The auxiliary shield member 14 and the shield case member 13 are placed in an electrically connected state by contacting the outer surface portion of the second lid-shaped portion 22.

The second printed wiring board 1 of the first printed wiring board 11 housed in the shield case member 13
2, the connector portion 18 provided on the first printed wiring board 11 is attached to the second
Of the second printed wiring board 12 connected to the connector portion 28 provided on the printed wiring board 12 of FIG.
The plurality of contact engagement pieces 14A of the auxiliary shield member 14 provided in the abutting contact the outer surface portions of the first lid-shaped portion 21 and the second lid-shaped portion 22 that form the shield case member 13, and the auxiliary shield member 14 and the shield case member 13 are placed in an electrically connected state. Then, the ground conductor portion 27 provided on the second printed wiring board 12 is actually electrically connected to the ground potential point to be supplied with the ground potential.

As a result, when the first printed wiring board 11 housed in the shield case member 13 is attached to the second printed wiring board 12, the first printed wiring board 11 is removed.
The shield case member 13 that substantially accommodates the entire printed wiring board 11 is a grounding conductor portion 17 provided on the first printed wiring board 11, and a connector portion 18 provided on the first printed wiring board 11. An indirect ground potential via a connector portion 28 provided on the second printed wiring board 12 to which the connector portion 18 is connected and a grounding conductor portion 27 provided on the second printed wiring board 12. In addition to being electrically connected to a point, a direct electrical connection to a ground potential point is made through the auxiliary shield member 14 and the grounding conductor portion 27 provided on the second printed wiring board 12. To be done.

Therefore, the impedance between the shield case member 13 and the ground potential point is made substantially negligible, and the ground potential is substantially given to the shield case member 13, and moreover, the shield case is provided. The member 13 is configured to substantially accommodate the entire first printed wiring board 11. As a result, the electromagnetic shielding of the circuit component mounting portion formed on the first printed wiring board 11 by the shield case member 13 is performed extremely well, and the circuit component mounting portion formed on the first printed wiring board 11 is The radiation interference with respect to is sufficiently suppressed.

[0026]

As is apparent from the above description, according to the circuit board shield device of the present invention, for example, the first circuit board as the child board and the second circuit board as the parent board to which it is attached Used in combination with the circuit board of the first
In forming the shield device for the circuit component mounting portion formed by the first circuit board, the shield case member substantially accommodating the entire first circuit board is
Provided on the second circuit board via the grounding conductor section provided on the circuit board, the connector section provided on the first circuit board and the connector section provided on the second circuit board, which are interconnected. Electrically connected to the grounding conductor portion provided on the second circuit board, and electrically connected to the grounding conductor portion provided on the second circuit board directly through the auxiliary shield member provided on the second circuit board. To be done.

As a result, the shield case member is provided on the first circuit board under the direct electrical connection between the grounding conductor portion provided on the second circuit board and the ground potential point. The grounding conductor part, the connector part provided on the first circuit board and the connector part provided on the second circuit board, and the grounding conductor part provided on the second circuit board. Is electrically connected to the indirect ground potential point via the auxiliary shield member and the second grounding conductor portion provided on the second circuit board. Connection is made. Therefore, the impedance between the shield case member and the ground potential point is substantially negligible, and the shield case member is substantially provided with the ground potential. Since the entire circuit board is substantially accommodated, electromagnetic shielding of the circuit component mounting portion formed on the first circuit board by the shield case member is performed extremely well, and as a result, the first circuit is provided. Radiation interference to the other due to the circuit component mounting portion formed on the substrate is sufficiently suppressed.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a circuit board shield device according to the present invention together with a circuit board to which the shield device is applied.

FIG. 2 is a perspective view showing an example of a circuit board shield device according to the present invention together with a circuit board to which the shield device is applied.

FIG. 3 is an exploded perspective view for explaining a shield case member that constitutes an example of a circuit board shield device according to the present invention and a circuit board housed therein.

FIG. 4 is a perspective view showing a conventionally proposed shield device for a circuit board.

[Explanation of symbols]

 11 1st printed wiring board 12 2nd printed wiring board 13 Shield case member 14 Auxiliary shield member 14A Contact engagement piece 15,25 Circuit component 16,26 Signal path formation part 17,27 Grounding conductor part 18,28, 29 connector part 19 conductor connection part for grounding 20 frame-shaped part 20A connection protrusion 20B cutout part 21 first lid-shaped part 22 second lid-shaped part

Claims (4)

[Claims] 1. A first circuit board is substantially housed in its entirety,
A connector that is provided on the first circuit board and has a first connector section that is electrically connected to the first signal path forming section and the first grounding conductor section of the first circuit board, and is exposed to the outside. A shield case member having an opening and electrically connected to the first grounding conductor portion and a second connector portion to which the first connector portion is connected are provided, and the first connector portion is provided. A second signal path forming part and a second grounding conductor part, to which the signal path forming part and the first grounding conductor part are electrically connected via the first and second connector parts, respectively. When the first connector portion is connected to the second connector portion while being electrically connected to the second grounding conductor portion, the shield case member is provided on the second circuit board. An auxiliary shield member that is in contact with and electrically connected to, Circuit board shield device consisting of. 2. A frame shape in which a shield case member substantially surrounds a peripheral end face portion of a first circuit board and is electrically connected to a first grounding conductor portion of the first circuit board. Part, a first lid-shaped part that engages with the frame-shaped part and covers one of the mutually opposed surfaces of the first circuit board, and an other part of the mutually opposed surface that is engaged with the frame-shaped part. The circuit board shield device according to claim 1, wherein the shield device is formed so as to include a second lid-shaped portion that covers the second lid-shaped portion. 3. The shield device for a circuit board according to claim 2, wherein the frame-shaped portion is provided with an opening forming portion which forms a connector opening portion. 4. The shield device for a circuit board according to claim 1, wherein the auxiliary shield member substantially surrounds the second connector portion.