JPH05136594A - Back board shield structure of electronic equipment case - Google Patents

Abstract

PURPOSE:To prevent electromagnetic waves from leaking out from a case through an opening provided to its back cover and electrostatic troubles by a method wherein an SG layer and an FG layer are formed on both sides of a shield wiring board as isolated from each other. CONSTITUTION:An SG film 16 is formed on the inner side of a shield wiring board 15 set on the rear side of a back board 4, and an FG layer 17 is formed on the opposite side of the shield wiring board 15. A contact spring 19 is interposed between the back board 4 and the shield wiring board 15 in the region of bias holes 14 to electrically connect the SG layer 16 formed on the shield wiring board 15 with the bias hole 14. A grounding pin 8 is made to come into contact with the SG layer 16 through a through-hole 20 provided to the shield wiring board 15. By this setup, the inner SG layer of a back board is electrically connected to the SG layer 16 of the shield wiring board 15. Therefore, a shield structure of this design induces the same effect that an inner SG layer is formed outside of the back board 4, so that it can be enhanced in shield effect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backboard shield structure for an electronic device constructed by accommodating a plurality of packages side by side in a housing and connecting the packages to a common backboard provided on the back side of the housing. Regarding

[0002]

2. Description of the Related Art As shown in FIG. 4, a general structure of an electronic device is such that a printed wiring board 3 is housed inside a casing along a number of rails 2 provided on a top wall and a bottom wall of a casing 1. , The connector protruding from the inner surface of the backboard 4 installed on the rear side of the housing is connected to each other to make a signal connection with each other, and the external cable is connected to the terminal protruding from the rear surface of the backboard 4. It connects to a connector to interface with external devices. The front plate 5 made of metal is attached to the front surface of the housing, and the back cover 6 made of metal is also attached to the back surface thereof to perform electromagnetic shielding.

The structure will be described in more detail on the back side of this housing. As shown in FIG. 5, a plurality of pins 8 that fit into the connectors 7 of the printed wiring board 3 are collected on the inner side of the backboard 4. The connector housing 9 is arranged, and on the other hand, on the back surface side of the backboard, the connector housing 12 is arranged in which a plurality of pins 11 to be fitted with the connector 10 of the external cable are put together.

As shown in FIG. 6, the back cover 6 has openings 13 corresponding to these connector housings 12. The connector 10 of the external cable is fitted into the connector housing 12 of the backboard through the opening 13.

[0005]

Recently, in electronic devices, particularly in transmission devices, the signal frequency has become higher as the line capacity has increased. Along with this, the wavelength of noise electromagnetic waves radiated becomes shorter, and the risk of electromagnetic waves leaking out of the housing even through a small gap is increasing. Particularly in the backboard, since many patterns are longer than other printed wiring boards, it is easy to radiate noise electromagnetic waves, and it has become unacceptable to provide an opening in the back cover as in the past as a measure for EMI.

It is an object of the present invention to provide a backboard shield structure for the purpose of preventing leakage of electromagnetic waves from the inside of the housing and electrostatic damage through the opening of the back cover.

[0007]

The object of the present invention is to accommodate a plurality of printed wiring boards in parallel inside a housing, and to project these signal pins on the inner surface side of a backboard which is arranged in a direction crossing the housing. The connector is connected to the back board, the external cable is connected to the signal pin protruding to the back side of the backboard, and a metal back cover is attached to the back side of the backboard for electromagnetic shielding. In the electronic device configured as described above, the shield wiring board is interposed between the backboard and the back cover, the SG layer is provided on the backboard-side surface of the shield wiring board, and the FG is formed on the opposite surface. Layers are provided inside the backboard S
A via hole that is electrically connected to the G layer is exposed on both sides of the backboard, and the inner SG layer of the backboard and the SG layer of the shield wiring board are electrically connected via a contact spring that comes into contact with the via hole. And SG of the backboard via the ground pin that penetrates both the shield and the wiring board.
And a SG layer of the shield wiring board are electrically connected, and further, the FG layer of the shield wiring board and the back cover are brought into direct contact so as to be electrically connected, thereby achieving a shield structure of a backboard. To be done.

[0008]

The shield wiring board is installed on the back surface of the backboard, and the SG layer and the FG layer are formed on both sides of the shield wiring board. Since the inner SG layer of the backboard is electrically connected to the SG layer of the shield wiring board through the contact spring and the ground pin, noise electromagnetic waves radiated from the inside of the housing are completely shielded by this and leakage to the outside is prevented. Get off. On the other hand, static electricity and noise electromagnetic waves arriving from the outside are shielded by the FG layer of the shield wiring board that is electrically connected to the back cover, so that they can be prevented from entering the inside.

Based on the preferred embodiment shown in the drawings,
The present invention will be described in more detail.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An electronic device to which a backboard shield structure of the present invention is applied has a printed wiring board arranged along a number of rails provided on a top wall and a bottom wall of the housing, as in the above-mentioned prior art. It is housed inside and connected to the backboard installed on the back side of the housing by a connector. Then, a metal front plate is attached to the front surface of the housing, and a metal back cover having an opening for an external cable connector is attached to the back surface to perform shielding. Hereinafter, only the differences from the conventional technique will be described in detail, and the same components will be denoted by the same reference numerals and description thereof will be omitted.

The main components of the present invention will be described with reference to the exploded perspective view shown in FIG. 1. The backboard 4 is fixed to the rear surface of the housing 1. A large number of pins 8 and 11 are implanted in the backboard 4, and the tips of the pins project on both sides of the backboard. The end of the pin 8 is the printed wiring board 3
The connector housing 9 is assembled so as to be fitted with the connector 7 mounted on the rear edge thereof. In the upper region of the backboard 4, there are provided via holes 14 filled with solder to expose an internal SG layer (not shown) on the surface. Further, a part of the pins (the uppermost pin in this example) is a ground pin 8'which is electrically connected to the internal SG layer.

A shield wiring board 15 is installed on the back surface side of the backboard 4. The inner surface of the shield wiring board 15, that is, the surface on the backboard side, is SG-coated with a conductive material.
The layer 16 is formed, and the FG layer 1 is also formed on the opposite surface.
7 are formed. As shown in FIG. 2, the shield wiring board 15 is provided with a through hole 18 at a position corresponding to the tip of the pin 11 protruding to the back surface side of the backboard 4, and the pins 11 and 8'are It penetrates through this through hole 18 and projects to the back surface side of the shield wiring board 15. The tips of the pins 11 and 8'are made so that they can be fitted into the connector 10 of the external cable.
It is summarized in 2.

A back cover 6 having the same construction as the conventional one is mounted on the back side of the shield wiring board 15. Backboard 4
The relationship between the wiring board 15 and the shield wiring board 15 will be described in more detail with reference to FIG. Backboard 4 and shield wiring board 1
5, a contact spring 19 is interposed in the region of the via hole 14 and elastically contacts the SG layer 16 of the shield wiring board 15 and the via hole 14 to electrically connect them. It is conducting. As a result, the internal SG layer of the backboard is electrically connected to the SG layer 16 of the shield wiring board.
Further, the ground pin 8'contacts the SG layer 16 through the through hole 20 of the shield wiring board 15. Therefore, also in this case, the internal SG layer of the backboard and the SG layer 16 of the shield wiring board are electrically connected. This produces the same effect as the internal SG layer is formed outside the backboard 4, and the shield effect is improved.

The back cover 6 is an FG of the shield wiring board 15.
Mounted in direct contact with layer 17. As a result, they are electrically connected and the opening 13 in the back cover is SG
This FG layer 17 which is completely separated from the layer 16 blocks the backboard side and provides a good shielding effect.

[0015]

As described above, according to the present invention, a shield wiring board having an SG layer and an FG layer, which are completely separated on both sides, is provided on the outside of the backboard, and the contact spring and the ground pin are used to interpose the shield wiring board. The internal SG layer of the backboard is electrically connected to the SG layer. Therefore, noise electromagnetic waves generated from the backboard side can be completely blocked by the SG layer of the shield wiring board.

Furthermore, since the back cover is attached to the back of the shield wiring board in contact with the FG layer, the connector opening formed in the back cover is shielded by this FG layer, and the back cover side is opened. Electromagnetic effects are completely cut off.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a main part of a shield structure of the present invention.

FIG. 2 is an assembled side sectional view of the shield structure of the present invention.

FIG. 3 is a partially enlarged view of FIG.

FIG. 4 is an exploded perspective view showing a conventional housing structure.

FIG. 5 is a side view of a conventional shield structure.

FIG. 6 is a perspective view of a conventional backboard and back cover.

[Explanation of symbols]

 1 ... Housing 3 ... Printed wiring board 4 ... Back board 6 ... Back cover 7 ... Printed wiring board connector 8 ... Pin 8 '... Ground pin 9 ... Connector housing 10 ... External cable connector 11 ... Pin 12 ... Connector housing 13 ... Back Opening of cover 14 ... Via hole 15 ... Shield wiring board 16 ... SG layer 17 ... FG layer 18 ... Through hole 19 ... Contact spring 20 ... Through hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiro Iino 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor, Shuichi Tokaibayashi 1015, Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited

Claims (1)

[Claims] 1. A signal which accommodates a plurality of printed wiring boards (3) in parallel inside a housing (1) and projects these to the inner surface side of a backboard (4) arranged in a direction traversing the housing. A connector is connected to the pin (8), an external cable is connected to the signal pin (11) protruding to the back side of the backboard (4), and further to the back side of the backboard (4). In an electronic device configured to mount a metal back cover (6) for electromagnetic shielding, a shield wiring board (15) is interposed between the back board (4) and the back cover (6). A via hole () is provided which has an SG layer (16) on the backboard side surface of the shield wiring board (15) and an FG layer (17) on the opposite surface side, and which is electrically connected to the internal SG layer of the backboard. 14)
Are exposed on both sides of the backboard (4), and the inner SG layer of the backboard and the SG layer (1 of the shield wiring board are provided via contact springs (19) contacting the via holes (14).
6) is electrically connected to the back board (4) and the shield wiring board (15) through an earth pin (8 ') penetrating both the back board (4) and the shield wiring board (15). 16) is electrically connected to the FG layer (17) of the shield wiring board and the back cover (6).
A backboard shield structure characterized by being in direct contact with and conducting.