JPH05291777A - Shield structure of electronic equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] When a material in which a conductive plane body such as a conductive sheet, metal foil, or metal mesh is encapsulated in plastic is used as an electromagnetic wave shield material, the plastic on the surface of the conductive plane-encapsulated plastic is used. The layers are removed to simply and surely ensure electrical connection at the edge of the case. [Structure] Providing a protruding structure such as undercut, slide, etc. on a mold for molding a conductive plane-encapsulated plastic,
By forming a thin part on the case and breaking it off at the thin part after molding, or by pulling out the case with the undercut state at the time of releasing after molding, the plastic layer is removed and the inner conductive flat body is removed. It is exposed on the edge of the case.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an electromagnetic wave shield material,
The present invention relates to a method for ensuring electrical connection at an end face of a conductive flat body-encapsulating plastic case in an electronic device using a material in which a conductive flat body such as a conductive sheet, a metal foil, and a metal mesh is encapsulated in plastic.

[0002]

2. Description of the Related Art In recent years, with the rapid spread of electronic devices, high frequency electromagnetic wave noise radiated from these devices has come to be regarded as a problem. By the way, as a method of preventing such electromagnetic noise, a casing made of a material having conductivity around the electronic device, for example, a casing made of metal, or metal sprayed on the inner surface of a plastic casing, metal plating,
It is better to shield it with a conductive paint. There is also a method of molding a case by mixing a conductive filler such as metal fiber into plastic.

In order to effectively shield electromagnetic waves, the conductive material used for the shield must have the ground of the substrate, which is the source of the electromagnetic waves, and have a plurality of conductivity forming the casing. It is important that an electrical connection is secured between the cases, for example, between the top case and the bottom case.

[0004] Conductive plastics, which are obtained by dispersing conductive fillers inside plastics, have recently attracted attention because of their good shielding properties, low production man-hours, and low final prices. However, although the inside of the plastic secures electrical conductivity by the function of the filler, a skin layer that is an insulating layer is formed on the outermost surface at the time of molding. Hard to get.

Further, as the electromagnetic wave shielding material, a material having a conductive plane body such as a conductive sheet, a metal foil or a metal mesh contained in the plastic may be used as a material having a function similar to that of the above conductive plastic. .. In the case of this conductive plane-encapsulated plastic material, in general,
Conductive sheets such as conductive sheets, metal foils, and metal meshes existing inside the plastic are not exposed at the case end faces, and it is difficult to obtain electrical connection between the cases simply by making contact at the end faces. ..

In the conventional apparatus, as described in JP-A-1-41300, a strip of conductive elastomer is attached to the end face of a conductive plastic by heat fusion or solvent bonding. During installation, the skin layer, which is an insulating layer, is ruptured by heat or solvent, and the conductive filler inside the plastic is electrically joined to the installed conductive elastomer, and the electrical conductivity at the end face of the conductive plastic is increased through this conductive elastomer. It was supposed to secure the joint.

[0007]

The above-mentioned prior art is intended to electrically bond the conductive filler inside the conductive plastic and the conductive elastomer by heat fusion or solvent bonding, which makes the work complicated. Accompanied. Further, the conductive elastomer to be bonded must be one suitable for heat fusion or solvent adhesion, and there is a problem that the material is limited.

An object of the present invention is to easily and surely obtain electrical connection at the end face of a conductive plane-encapsulated plastic.

[0009]

In order to achieve the above-mentioned object, a die for molding a conductive plane-body-encapsulated plastic is provided with an undercut, slide, or other protruding structure (hereinafter referred to as the protruding structure) to form a molded product. V shape, U shape, step shape,
A notched thin portion such as a convex shape or a concave shape is formed, and after molding, the thin portion is folded off to expose the conductive plane body existing inside the plastic to the end face.

Further, an undercut is provided in a mold for molding the conductive plane-body-encapsulated plastic, and when the mold is released after molding, the case is pulled out in the undercut state to remove the plastic layer, The conductive plane body is exposed at the end face.

According to the above-mentioned procedure, by simply breaking off the case end after molding or removing the case from the mold after molding, electrical connection can be easily and surely made to the end face of the conductive plane encapsulating plastic. A secure surface can be formed.

[0012]

If a protruding structure is provided in the mold near the end face that secures the electrical connection of the conductive plane-encapsulated plastic, a thin portion is formed in the case near the end face, and the end face portion can be easily broken off. .. The surface of the conductive plane-encapsulated plastic is covered with a plastic layer that is an insulating layer during molding, so it is difficult to obtain electrical connection at the end face, but if the end is broken off, the conductive plane body inside will be attached to the end face. It becomes exposed, and electrical connection can be easily secured at the end face.

In the case where the die is provided with the protruding structure to form the thin wall portion, compared with the case where the protruding structure is not provided, the thin portion can be folded at the set thin portion, so that the breaking point is determined. Further, since the end surface after being broken off becomes a flat surface, it becomes easy to secure electrical connection.

[0014]

EXAMPLES Examples of the present invention will be described below. FIG. 2 shows a cross-sectional view of the electrically conductive flat body-containing plastic after molding.
The conductive plane-body-encapsulated plastic 1 is composed of a conductive plane body 2 such as a conductive sheet, a metal foil, a metal mesh and the like, and a plastic layer 4 which is an insulating layer existing on the surface.
The conductive plane body 2 is not exposed on the surface of the plastic layer 4. In this embodiment, the base material plastic 4 is A
The BS resin was used, and the conductive plane member 2 was an expanded metal made of aluminum. Base material plastic 4
Is not limited to ABS, polystyrene, polycarbonate,
There is no particular limitation as long as it is a general thermosetting resin such as modified PPO. The material of the conductive flat body 2 is not limited to aluminum, but may be copper, stainless steel, or the like, and the shape is not limited to expanded metal, but may be metal foil, a conductive sheet, or the like, and the electrical conductivity commonly used for electromagnetic wave shielding. There is no particular limitation as long as it is a planar body having.

FIG. 3 (a) is a perspective view of a terminal device in which a housing is made of a conductive plane-encapsulated plastic, and FIG. 3 (b) is a cross-sectional view of a joint portion between its upper and lower cases. The terminal device is formed of a top case 5, a bottom case 6, and a CRT cover 7 which are made of a conductive plane-encapsulated plastic. In the case of the conductive plane-body-encapsulated plastic, the surface of the end face of the case is covered with the plastic layer which is the insulating layer.
It is difficult to obtain electrical connection between both covers with a and 8b.

FIG. 4 shows a method for producing a conductive flat body-containing plastic according to the present invention. The male die 10 is combined with the female die 9 for injection molding, the conductive plane body 2 is set inside, and the die is closed as shown in FIG. Thereafter, the resin injection port 1 provided in the closed male mold 10
From 1, the melted plastic 12 is injected to form a conductive plane-encapsulated plastic cover having a conductive plane body therein. In the female mold 9 and the male mold 10 of the injection molding die, the protruding structures 13a, 13b are provided in the vicinity of the end faces 14a, 14b of the molded conductive flat intrabody plastic 12.
To provide. Due to the presence of the protruding structures 13a and 13b, the end surface 14a of the conductive planar in-plane encapsulating plastic 12 is
Thin portions 15a and 15b are formed near 14b. After molding, remove the case with ejector pin 16. In addition, undercuts 13c and 13d are formed on the mold at the end of the boss portion 22.
To provide. Due to the presence of the undercuts 13c and 13d, a thin portion 15c is formed. After molding, remove the case using the slide structure.

An embodiment of the present invention will be shown. FIG. 1A is a sectional view of an embodiment of the present invention. At the end of the bottom case, there is shown a thin portion 15 and a tip portion 17 formed by the protruding structures 13a and 13b of the mold. The portion in contact with the mold, that is, the surface of the conductive plane-encapsulated plastic case is the plastic layer 4 and thus the insulating layer. By applying force to the thin portion 15 and breaking off the tip portion 17, the conductive plane body 2 is exposed on the end face. FIG. 1 (b) is a sectional view showing how the upper and lower cases are joined according to the present invention. By forming the exposed end faces 18a and 18b of the conductive flat body 2 on the top case 5 and the bottom case 6 and joining the end faces, the electrical joining of the upper and lower covers can be ensured easily and reliably. Thin part 15 with tip 1
A mechanical force is sufficient to break off 7. Further, by providing the undercuts 13a and 13b, the end faces 18a and 18b where the conductive plane body 2 is exposed
Can have a flat surface with a high degree of certainty for ensuring electrical connection.

The larger the area of the exposed end surface 18 of the conductive plane member 2 is, the more stable the electric connection can be obtained, but 10 mm ² is sufficient. If the size is smaller than this, the volume occupied by the conductive plane body in the conductive plane body-encapsulated plastic is not so large that it becomes difficult to obtain a reliable electrical connection. Further, in this embodiment, a case having a thickness of 3 mm was used, but the height of the protruding structure of the mold at this time was 1 mm in total in the left and right directions. A suitable height of this protruding structure is 0.5 mm to 2 mm. 0.
If it is smaller than 5 mm, the thin portion is too thick to be easily broken off, and if it is larger than 2 mm, the area of the end face 18 where the conductive plane member 2 is exposed becomes small.

Another embodiment of the present invention will be described. 5 (a) (b)
[Fig. 3] is a perspective view and a cross-sectional view of a case where a conductive bonding material 20 is attached to the end surface 18 where the conductive flat body 2 is exposed. According to the above-mentioned embodiment, the thin wall portion 15 is formed by providing the die with the protruding structure 13, and the thin wall portion 15 is used to form the tip portion 1.
The end face 18 that exposes the conductive plane member 2 inside is formed by breaking off 7. Even in this state, it is possible to sufficiently secure the electric connection, but in order to further secure the electric connection and to give elasticity to the connecting portion, the end face 18
The conductive bonding material 20 was attached to the. In this embodiment, as the conductive bonding material 20, a conductive gasket covered with a nylon fiber cloth coated with a urethane core material is used, but a conductive finger having elasticity such as a beryllium copper shield finger is used. The material is not particularly limited as long as it is a good material. To bond the end face 18 and the conductive bonding material 20,
The double-sided conductive tape 21 was used. A conductive adhesive may be used for the adhesion. FIG. 5 (b) shows an example of mounting on a case, in which the ends of the bosses 22a, 22b are the exposed end surfaces 18a, 18b of the conductive flat body 2, and the conductive gasket 20 is attached thereto with the conductive double-sided tape 21. Is.

An example in which the present invention is used to secure the ground of a substrate will be shown. FIG. 6A is a perspective view of the substrate 23 and the bottom case 6,
FIG. 6B is a sectional view thereof. The bottom case 6 is made of a conductive plane-encapsulated plastic, and the tip portion 26a of the screw-fastening boss 26 for fixing the substrate 23 exposes the conductive plane body 2 to the end face by the above-mentioned method, thereby electrically connecting. Make sure it can be secured. A metal ground pattern portion 24 for dropping the ground is installed on the substrate 23. The ground pattern portion 24 is aligned with the screw-fastening boss 26,
By tightening the screw holes 25, the ground of the board 23 can be dropped to the bottom case 6. It is desirable for assembly that electrical connection is made by the ground pattern portion 24 and the boss 26 and mechanical connection is made by screwless.

[0021]

EFFECTS OF THE INVENTION According to the present invention, the conductive structure is provided in the mold in the vicinity of the end of the plastic body and the mold is provided with a projecting structure, and the plastic layer is removed by breaking off at the thin portion or by undercutting. Since the conductive plane body can be exposed on the surface of the plane-body-encapsulated plastic, electrical connection at the end face of the plane-body-encapsulated plastic can be easily and reliably ensured.

[Brief description of drawings]

FIG. 1 is a cross-sectional view when an end portion is broken off.

FIG. 2 is a cross-sectional view of a conductive plane-encapsulated plastic.

3A and 3B are a perspective view and a cross-sectional view of a conductive flat body-containing plastic case.

FIG. 4 is a cross-sectional view at the time of molding a conductive flat body-containing plastic.

5A and 5B are a perspective view and a cross-sectional view when a conductive bonding material is attached.

6A and 6B are a perspective view and a cross-sectional view when the substrate is grounded.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Conductive plane body inclusion plastic, 2 ... Conductive plane body, 4 ... Plastic layer, 5 ... Top case, 6 ... Bottom case, 7 ... CRT cover, 8a ... Top case end part, 8b ... Bottom case end part, 9 ... Female mold for injection molding, 10 ... Male mold for injection molding, 11 ... Resin injection port, 12 ... Molten resin, 13, 13a, 13b, 13c, 13d ... Projection structure, 14a, 14b ... Case end face, 15, 15a, 15b, 15c ... Thin portion, 16 ... Ejector pin, 17, 17a, 17b ... End portion, 18, 18a, 18b ... End face exposing conductive plane body, 20 ... Conductive contact Material, 21 ... Double-sided conductive tape, 22, 22a, 22b ... Boss portion, 23 ... Board, 24 ... Ground pattern portion, 25 ... Screw hole, 26 ... Screw fastening boss.

Claims (4)

[Claims] 1. When an electromagnetic wave shielding material is made of a material in which a conductive plane body such as a conductive sheet, a metal foil or a metal mesh is enclosed in plastic, the above-mentioned electrical connection of the conductive plane body-containing plastic case is performed. On the end face to be secured, a protruding structure such as undercut and slide is provided in the mold near the end face, and a notched thin portion such as V-shaped, U-shaped, stepped, convex, concave is formed on the molded product, and molding is performed. A shield structure for an electronic device, characterized in that a conductive plane body such as a conductive sheet, a metal foil, a metal mesh, etc. existing inside the plastic is exposed at an end face by being later broken off at the thin portion. 2. The shield structure for an electronic device according to claim 1, wherein a conductive plane body such as a conductive sheet, a metal foil, a metal mesh, etc., present inside a conductive plane body-containing plastic case is provided. A shield structure for electronic devices, in which a conductive contact material is attached to the exposed end surface. 3. The shield structure for an electronic device according to claim 1, wherein a mounting portion and a substrate having a ground pattern portion are mounted on the mounting portion, the mounting portion is mounted at a position corresponding to the mounting portion of the substrate. In a case for an electronic device having a projecting portion, a conductive flat body such as a conductive sheet, a metal foil, a metal mesh, etc. existing inside the plastic is exposed at the end face of the projecting portion, the shield structure of the electronic device. .. 4. An injection molding die is provided with an undercut for removing the plastic layer after molding, a protruding structure such as a slide, and the molded product is V-shaped, U-shaped, step-shaped, convex-shaped,
A method for molding a material in which a conductive flat body such as a conductive sheet, a metal foil or a metal mesh is encapsulated in plastic by forming a notched thin portion such as a recess.