JPH0142392Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to an electromagnetic wave shielding case.

In recent years, with the spread of electronic calculators, the electromagnetic waves emitted by electronic calculators are having a negative impact on nearby televisions and radios, and are even causing other electronic calculators to malfunction, making it necessary to shield electromagnetic waves. ing. An easy way to shield electromagnetic waves is to make the material of the case that blocks the electronic circuit that generates electromagnetic waves conductive.

Conventionally, in order to make the case conductive and improve the electromagnetic shielding effect, it was necessary to apply conductive paint mixed with conductive material powder such as nickel, copper, or carbon to the case, or to make the entire case a copper plate. Metal or carbon powder or fibers are mixed into resin and kneaded to form a case. However, when a conductive paint is applied to the inside of the case, there is a problem in that the paint peels off and falls onto the electronic circuit, causing the circuit to be shot. Furthermore, if a conductive paint is applied to the outside of the case, an additional top coat must be applied to improve the appearance of the product, which increases the cost accordingly. Furthermore, if the case is made by processing a copper plate, there are restrictions on the shape and the case becomes heavy. Furthermore, if the case is molded by mixing metal or carbon powder or fibers into the resin, a sufficient shielding effect cannot be expected because the resin, which is an insulator, is interposed between the conductors. Moreover, since the conductor is exposed on the surface of the molded product, it is necessary to paint it, which increases the cost.

The present invention was developed after studying an inexpensive and highly reliable electromagnetic shielding case that eliminates the drawbacks of conventional shielding methods caused by the conductive layer being exposed on the surface of the molded product. They discovered that the objective could be achieved by insert molding a conductive sheet consisting of layers, and completed the present invention.

The present invention will be explained below using figures.

The figure shows the process of manufacturing the electromagnetic shielding case of the present invention, and Figure 1 shows the plastic layer 1.
and a metal layer 2. The plastic for the plastic layer is preferably a thermoplastic resin, particularly high-density polyethylene, polypropylene, polystyrene, polycarbonate, fluororesin, or vinyl acetate resin. Further, the metal of the metal layer is preferably copper, aluminum, nickel, tin, or iron.

FIG. 2 shows the conductive sheet 3 with 7 and
The pattern shown in the figure is etched using printing or photographic methods similar to the methods used to fabricate printed circuits. The size of the pattern is preferably as small as possible in order to enhance the shielding effect, and the line width is preferably about 0.2 mm. The pattern shown in FIG. 7 allows the conductive sheet 3 to be stretched in one direction, and the pattern shown in FIG. 8 allows the conductive sheet 3 to be stretched in two directions.

Therefore, when performing insert molding using the conductive sheet 3, the conductive sheet stretches and is not cut.

FIG. 3 is a sectional view showing the process of inserting the etched conductive sheet 3 into a preform by vacuum forming into a mold for a molded product. The resin to be molded may be any general-purpose thermoplastic resin or thermosetting resin with good fluidity.

Another method shown in FIGS. 4 to 6 is to set the etched conductive sheet 3 in the mold cavity with a clamp 8 in FIG. 4, and then set the mold as shown in FIG. By closing the molded product and injecting the resin as shown in FIG. 6, the metal layer 2 of the conductive sheet 3 can be molded without being exposed on the surface of the molded product.

The electromagnetic shielding case of the present invention is easy to manufacture, has a highly reliable electromagnetic shielding effect, and is inexpensive.

[Brief explanation of the drawing]

FIG. 1 shows a conductive sheet, and FIG. 2 shows an etched metal layer of the conductive sheet. FIG. 3 shows a cross-sectional view of the step of vacuum forming the etched conductive sheet. FIG. 4 is a sectional view showing the steps of setting the conductive sheet into the mold cavity, FIG. 5 showing the closing of the mold, and FIG. 6 showing the steps of injecting the resin. FIGS. 7 and 8 show an example of an etching pattern (the white portion is removed by etching). 1...Plastic layer, 2...Metal layer, 3...
Conductive sheet, 4... Mold cavity, 5... Mold core, 6... Resin, 7... Gate, 8... Clamp.

Claims (1)

[Scope of utility model registration request] An electromagnetic shielding case obtained by insert molding a conductive sheet consisting of a plastic layer and a metal layer, characterized in that the metal layer of the conductive sheet is etched in advance before insert molding. .