JPH06268390A - Electromagnetic shield case - Google Patents

Abstract

PURPOSE:To provide an electromagnetic shield case, which is able to provide stable, high shielding effect against electromagnetic wave and which can be produced by simple metal plating with an ordinary electrolytic plating method even to complicated shapes. CONSTITUTION:This comprises a main body of case consisting of scattered plastic 13 of conductive fibers 12 and a metal plating layer 15 laminated on the inner surfaces 14 of the main body of case; and conductive fibers 12a near the inner surfaces of the main body of said case are exposed from the inner surfaces of the main body of said case and touches the rear side of said metal plated layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic electromagnetic wave shielding case which is preferably used as a housing for electronic equipment.

[0002]

2. Description of the Related Art For example, plastics are often used as a housing material for electronic appliances such as laptop computers, laptop computers, and AC adapters because of their advantages such as workability, economy, and lightness.

However, since the plastic allows electromagnetic waves to pass therethrough, electromagnetic waves (EMI: Electr) such as deletion of stored information and erroneous operation of equipment are caused.
omagnetic Interference) may occur. Therefore, an electromagnetic shielding case made of plastic has come to be used as the housing.

As a conventional plastic electromagnetic wave shielding case, (1) the whole plastic case is metal-plated by electroless plating, (2) the inner surface of the plastic case is affixed with aluminum foil or the like, and (3) carbon. Known are plastics in which conductive fibers such as fibers and copper fibers are dispersed, and (4) those in which the inner surface of the case is coated with a conductive paint.

However, the case (1) has a problem that the electroless plating method used for metal-plating plastic is complicated in process and inferior in working efficiency as compared with a general electrolytic plating method. In addition, since a metal plating layer is formed on the entire surface of the case, it is necessary to mask the areas that do not require plating in advance. Further, when the masking treatment is omitted, a pretreatment such as an undercoat is additionally required after the plating treatment on a portion such as a product surface that needs to be coated, and the workability problem cannot be solved. On the other hand, the case (2) has a problem that not only a new step for attaching aluminum is required, but also a case having a complicated shape becomes difficult to handle. (3) and (4)
In case (2), there is a problem in that the conductive fibers and the conductive paint are likely to be non-uniformly dispersed, and it is difficult to obtain a stable electromagnetic wave shielding effect.

[0006]

SUMMARY OF THE INVENTION The present invention has been proposed in order to solve all of these problems and has a high shielding effect against electromagnetic waves, and moreover, it is a common electrolytic material in the production. Metal plating can be easily performed using the plating method, and in addition, complex shapes can be manufactured,
Furthermore, it is an object of the present invention to provide an electromagnetic wave shielding case in which the outer surface of the case can be easily coated.

[0007]

That is, the present invention is
A case body made of a plastic in which conductive fibers are dispersed, and a metal plating layer laminated on the inner surface of the case body, wherein the conductive fibers near the inner surface of the case body are exposed from the inner surface of the case body to form the metal. The present invention relates to an electromagnetic wave shielding case, which is in contact with the back side of a plating layer.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. 1 is a sectional view showing an example of an electromagnetic wave shielding case of the present invention, FIG. 2 is an enlarged sectional view of an essential part thereof, FIG. 3 is a sectional view of a case body, and FIG. 4 is a diagram showing an outline of an electromagnetic wave shielding effect measuring method. .

As shown in FIGS. 1 and 2, the electromagnetic wave shielding case 10 of the present invention includes a case body 11 and a metal plating layer 15 laminated on the inner surface 14 of the case body 11.
It consists of and. Reference numeral 19 is a surface coating layer provided as necessary.

The case body 11 is made of a plastic 13 in which conductive fibers 12 are uniformly dispersed, and is formed into a desired housing shape for electronic equipment such as a laptop computer by injection molding or the like. The method of molding the case body is not particularly limited, and press molding, blow molding, and the like other than injection molding are appropriately selected depending on the shape of the product and the type of plastic used.

The conductive fiber 12 used in the case body 11 is preferably a known conductive fiber made of stainless steel, aluminum, copper, carbon or the like, or glass fiber plated with aluminum or the like. The conductive fiber 12 is appropriately selected depending on the type of the plastic 13 to be mixed, the case to be molded, and the like.
It is used after being formed into an appropriate fiber shape having a size of about 00 mm.

The amount of the conductive fiber 12 added to the plastic 13 can be appropriately determined depending on the physical properties required of the case body 11 and the like, and is from 5% by weight to 50% by weight.
About wt% is preferable. If the amount of the conductive fibers 12 added is less than 5% by weight, not only the physical properties of the case body are insufficient, but also the metal plating layer 15 cannot be reliably formed inside the case body 11. On the other hand, if it is more than 50% by weight, it becomes difficult to mold the case body 11 itself.

As the plastic 13 used for molding the case body 11, a known plastic which can be molded by dispersing the conductive fibers 12 is used. If the plastic 13 is a thermoplastic resin, for example, acrylonitrile-butadiene-styrene resin, polyamide, polypropylene, polyphenylene ether, polybutylene terephthalate, and alloy materials thereof, such as a thermosetting resin, phenol resin, urea resin. ,
A polyester resin or the like is preferably used.

On the inner surface 14 of the case body 11, the conductive fibers 12 dispersed in the vicinity thereof are exposed on the surface. A metal plating layer 15 described below is laminated integrally on the exposed conductive fiber 12a with the back surface thereof in contact. As shown in FIG. 3, the exposed conductive fibers 12a are obtained by thinly removing the plastic on the inner surface 14 to which metal plating is applied after molding the case main body 11 and dispersing the conductive fibers 12 in the vicinity thereof. Obtained by exposing to the surface. This is because when injection-molding a plastic in which conductive fibers are dispersed, the melted plastic flows along the mold surface and solidifies, so the surface of the resulting molded product is covered with the plastic and the conductive fibers are almost free. This is because it is not exposed.

The method of exposing the conductive fibers 12 near the inner surface of the case body 11 is not particularly limited, and the shape of the case body may be changed by blasting, removing the plastic surface by sanding, or removing the plastic surface by flame. It is appropriately selected depending on the type of plastic used for molding.

The presence of the exposed conductive fibers 12a imparts high conductivity to the inner surface 14 of the case body 11, so that a metal plating layer can be easily formed on the surface by an ordinary electrolytic plating process. You can

On the other hand, the outer surface of the case body 11 is not subjected to blast treatment or the like, and the conductive fibers 12 are barely exposed. Therefore, conductivity of the outer surface of the case body 11 is low, and even if the entire case body 11 is immersed in a plating solution and subjected to normal electrolytic plating, the metal plating layer is not formed on the outer surface of the case body 11. Therefore, the case body 1
The surface coating layer 19 can be applied to the outer surface of No. 1 without treatment such as undercoating.

As the metal used for the metal plating layer 15, those generally used in the known electrolytic plating method are suitable, and one or more kinds of copper, nickel, chromium, zinc and the like are appropriately combined.

Next, the electromagnetic wave shielding effect of the electromagnetic wave shielding case of the present invention was measured as follows. (1) First, using a plastic compound having the following composition, injection molding is performed to obtain 150 × 150 × 3.
It is formed into a plate body of (mm). Acrylonitrile-butadiene-styrene resin 70% by weight Copper fibers (average fiber length 5 mm) 30% by weight (2) One side of the obtained plate body is thinly removed by shot blasting, and conductive fibers near the removed surface are exposed on the surface. Let (3) A copper-nickel plating layer having a thickness of 2 μm is integrally formed on the removed surface by electrolytic plating. (4) The electromagnetic wave shielding effect of the plate body (sample piece) provided with the plating layer is measured by the KEC method (method of Kansai Electronics Industry Promotion Center Hariya). The results are shown in the table below.

In the KEC method, as shown in FIG. 4, a sample S is placed in a space surrounded by a metal and irradiated with an electromagnetic wave, and the intensity of the electromagnetic wave incident on the sample S and the electromagnetic wave transmitted through the sample S are measured. It is a method of evaluating the electromagnetic wave shielding effect by measuring the intensity. The electromagnetic wave shielding effect in this case; SE (dB) is expressed by the following equation. SE = 20 log (E1 / E2) E1; Incident electric field intensity (V / m) E2; Transmission electric field intensity (V / m)

In order to compare with the product of the present invention, the electromagnetic wave shielding effect is similarly applied to the case of copper-nickel plating or the case made of aluminum by the electroless plating method on the ordinary plastic to which the conductive fiber is not added. To measure.

[0022]

As can be seen from the table, the electromagnetic wave shielding case according to the present invention is comparable to a case in which ordinary plastic is copper-nickel plated by electroless plating or an aluminum case. An electromagnetic wave shielding effect can be obtained.

[0024]

As shown and described above, the electromagnetic wave shielding case of the present invention is provided with a case or a conductive coating film which can surely shield electromagnetic waves and which is made of only plastic in which conductive fibers are dispersed. Compared to the simple case, since it has a metal plating layer on the inner surface, a stable electromagnetic wave shielding effect can always be obtained.

Further, in the electromagnetic wave shielding case of the present invention, it is not necessary to stick an aluminum foil or the like on the inner surface of the case at the time of manufacturing, so that it is possible to cope with a complicated shape. Moreover, since it can be manufactured using the usual electrolytic plating method, the work required for plating is simplified compared to the electroless plating method, and even when coating the outer surface of the case, painting such as undercoat or topcoat Therefore, it is possible to easily and economically manufacture. Actually, when comparing the present invention product having the same shape and coated on the outer surface with the conventional electroless plated product, it was possible to achieve a cost reduction of about 30%.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of an electromagnetic wave shielding case of the present invention.

FIG. 2 is an enlarged cross-sectional view of the relevant part.

FIG. 3 is a cross-sectional view of a case body.

FIG. 4 is a diagram showing an outline of an electromagnetic wave shielding effect measuring method.

[Explanation of symbols]

 10 Electromagnetic Wave Shielding Case 11 Case Body 12 Conductive Fiber 13 Plastic 14 Inner Surface 15 Metal Plated Layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shozo Kato 28, Futamata, Kitaura, Koushida-cho, Toda-gun, Miyagi Prefecture Tohoku Inoac Co., Ltd. (72) Inventor Shinichiro Nishimura 2-9-12 Osaki, Shinagawa-ku, Tokyo Stock Company Inoac Corporation

Claims (1)

[Claims] 1. A case main body made of plastic in which conductive fibers are dispersed, and a metal plating layer laminated on the inner surface of the case main body. The conductive fibers near the inner surface of the case main body are separated from the inner surface of the case main body. An electromagnetic wave shielding case, which is exposed and is in contact with the back side of the metal plating layer.