JPS61127197A - Plastic housing having electromagnetic wave shielding property - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a glass housing having VTL wave shielding properties, and is suitable for office, home, industrial, and other uses.
It is useful as a nousing for accommodating medical electronic equipment to prevent leakage of electromagnetic waves generated from the electronic equipment and to prevent interference due to electromagnetic waves generated from other equipment.

(Prior Art and its Problems) Currently, many housings for electronic devices are made of plastic molded products from the viewpoints of light weight, durability, freedom of design, and economy.

However, due to the electrical insulating properties of plastics, electromagnetic waves can pass through them5, so the electromagnetic waves generated inside the device may leak and have a negative impact on peripheral devices, or the device itself may be affected by interference from the outside. The problem of electromagnetic interference, such as malfunctions, has become increasingly serious.

Traditionally, shielding has been done with metal plates or nets, but these are hard and difficult to work with, and their high specific gravity makes them inconvenient to transport. Have difficulty.

It also has the disadvantage that it rusts easily, which shortens its useful life.

Zinc spraying and coating with conductive paint are used to directly impart conductivity to plastic housings and shield them from electromagnetic waves. Zinc spraying has been used for a long time as a shielding method for plastic housings, and has an excellent shielding effect. However, this method poses a problem in the adhesion between the plastic substrate and the applied zinc coating. If the zinc coating easily peels off or cracks occur, the shielding effect will be reduced.

Furthermore, the zinc spraying method has drawbacks such as negative effects of zinc vapor on the human body and noise.

By conductive paint. In the case of the i-manufacturing method, it is difficult to apply a coating with a uniform thickness, and although a thicker coating increases the shielding effect, there is a risk that the coating will crack or peel off.

(Means for Solving the Problems) The above is an overview of the conventional techniques.The present invention aims to eliminate the drawbacks of these conventional techniques. It also has a high electromagnetic shielding effect, and as shown in Figure 1, an electroless plating layer (such as nickel, copper, chromium, etc.) of nickel, copper, chromium, etc. 2), a structure in which an adhesive layer (3) and an electrically insulating plastic film layer (4) are laminated, or as shown in FIG. Plating layer (2), the same applies to the entire surface or part of the other side (plating layer (2), adhesive layer (
3) It has a structure in which electrically insulating plastic film layers (4) are laminated.

The housing base material of the plastic housing of the present invention is A
BS resin (acrylonitrile-butadiene-styrene copolymer resin), modified polyphenylene oxide resin, polystyrene resin, polycarbonate)/ABS resin composite is suitable.

The plating layer (2) has a thickness of 0.5 to 10 μm, more specifically 1 to 2 μm, and has a surface resistance value of lO-' to 10"Ω. It has a conductivity of 10"Ω or more. In this case, sufficient electromagnetic shielding effect cannot be obtained, and the lower the surface resistance value is, the better the shielding effect will be.

Considering these conditions, economy, and rust resistance, the plating layer (2) is preferably electroless nickel plating, which can be applied not only to one side of the housing base material (1) but also to the entire surface or a part of both sides. When a higher electromagnetic shielding effect is required, it is particularly preferable to provide electroless nickel plating layers on both sides.

The adhesive layer (3) is polyurethane-based or epoxy resin-based.

Adhesives such as acrylic resins, metal adhesive resins such as ionomer resins, ethylene-acrylic acid copolymer resins, ethylene-methacrylic acid copolymer resins, etc. are used.

The electrically insulating plastic film layer (4) is made of polypropylene, polyvinyl chloride, polyethylene terephthalate, polycarbonate, polyamide.

Plastic films such as polysulfone and polyimide are suitable, and have a thickness of 10 to 100 μm.

The surface resistance value is 1011-10+11Ω.

Next, the present invention will be described in detail with reference to specific examples and comparative examples.

(Example) Electroless nickel plating (film thickness: 2 μm) was applied to a portion of both sides of an ABS resin housing base material, and then a polyurethane-based two-component reactive adhesive (film thickness: 5 μm) was applied to one side of the base material. ) was applied with a polyethylene terephthalate film (thickness: 30 μm), which was used as the plastic housing of the present invention.

In Examples, the electromagnetic shielding effect was measured by the Takeda Riken method using a 150×150×21111 test piece.

(Comparative Example) An ABS resin plate (150 x 150 x 27111) coated with a nickel-based conductive paint (film thickness: 50 μrrL) on one side was used as a comparative example, and the electromagnetic shielding effect was measured using the Takeda embedding method.

The measurement results are shown in Table 1.

Table 1 Shielding effect against electric and magnetic fields (dB)
As shown in Table 1, the plastic housing of the present invention (
Example) has a sufficient shielding effect of 30 to 70 dB against electric and magnetic fields at 20 to 1 OOOMHz, and the nickel-based conductive paint (comparative example)
A higher shielding effect was obtained compared to Adhesion between the ABS resin housing and the electroless nickel plating layer and between the electroless nickel plating layer and the polyethylene terephthalate film was also good, and the film thickness of the electroless nickel plating was uniform.

(Effects of the Invention) Since the present invention has the above configuration, it has the following excellent practical effects.

(a) Since an electrically insulating plastic film layer is further provided on the conductive layer, there is no risk of electric shock or leakage, and furthermore, oxidation and corrosion of the conductive layer can be prevented.

(b) Since the conductive layer is provided on the housing base material by C plating, the thickness is uniform, and the thickness can be easily changed depending on the level of electromagnetic shielding required.

In addition, compared to conventional conductive paints, a high shielding effect can be obtained with a thinner thickness, and the adhesion to the welding base material is also good and there is no risk of peeling.

(c) If the conductive layer is an electroless plating layer of nickel, it will be superior in terms of conductivity and economy compared to copper chromium or the like.

) A high electromagnetic shielding effect can be obtained by applying a plating layer to the entire surface of the plastic base, but a sufficient electromagnetic shielding effect cannot be achieved even if the plating is applied only partially around the electromagnetic wave emitting part of the equipment housed in the housing. can get.

Furthermore, by plating both sides of the plastic material that serves as the base, a high electromagnetic shielding effect can be obtained.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a sectional view showing the layer structure of the first embodiment, and FIG. 2 is a sectional view showing the layer structure of the second embodiment. (1)...Housing base material (2)...Plating layer (3)...Adhesive layer

Claims (2)

[Claims] (1) A plastic housing having electromagnetic shielding properties and having a laminated structure in which a plating layer is provided on the entire surface or a portion of at least one side of a plastic base material, and an electrically insulating plastic film layer is further provided on the plating layer. (2) Claim 1 having a laminated structure in which plated layers are provided on both sides of a plastic base material, and an electrically insulating plastic film layer is further provided on the plated layer on one side.
A plastic housing having electromagnetic shielding properties as described in .