JPS59219999A - Method of producing electromagnetic wave shielding case - 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 TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for manufacturing an electromagnetic shielding case having a -C configuration by fitting two or more electromagnetic shielding synthetic resin molded products.

[Technical Background of the Invention] In recent years, with the development of digital electronic devices, the electromagnetic waves generated by these electronic devices may interfere with other devices such as nearby televisions, or may cause malfunctions due to electromagnetic waves from other devices. There is a big problem of causing
-It's getting more and more popular.

These problems can be solved by providing an electromagnetic shielding effect to the case surrounding the electronic circuit.

However, in such a case, monoproductivity, economic efficiency,
Synthetic resin products are often used from the viewpoint of lightness, etc., and due to technical constraints of injection molding and convenience in assembling internal equipment, products are manufactured by fitting two or more molded products together. has been done.

Various methods have been used to provide electromagnetic shielding properties to such cases, as described below.

(a) A metallic electromagnetic shielding layer is provided on the outer or inner surface of the synthetic resin case by plating, painting, thermal spraying, adhesive, etc.

([1) A case is molded from a thermoplastic resin mixed with a conductive filler such as metal powder, carbon powder, metal foil, metal SaW, carbon fiber, etc.

[Problems with the Background Art] However, in the method (a) among these methods, the electromagnetic shielding layer peels off due to the impact caused by dropping, thermal shock, etc.! [L, or falls off d3, and if the peeled piece falls onto the electronic circuit (j
However, there was a problem in that it could easily lead to serious accidents such as short circuits and fires.

In addition, C (d3) in the (mouth) method usually has a smooth appearance,
In order to prevent static electricity, the surface temperature of the mold cavity is raised to 7K (depending on the type of thermoplastic resin).
60℃ or higher) (Molding prevents the conductive filler from being exposed to the surface of the molded product, but as a result, there is no contact of the conductive filler at the fitting part of the electromagnetic shielding case, and this area is where electromagnetic waves Therefore, the contact surface of the fitting part had to be removed until the conductive filler was uniformly exposed, resulting in a drawback that secondary processing was time-consuming.

[Object of the Invention] The present invention has been made in order to address the above-mentioned problems, and the 8! An object of the present invention is to provide a method for manufacturing an electromagnetic shielding case that has electrical properties.

[Summary of the Invention] That is, the method for manufacturing an electromagnetic shielding case of the present invention involves manufacturing an electromagnetic shielding case constructed by fitting two or more molded products made of electromagnetic shielding synthetic resin. A metal plate is inserted into the mold cavity of the part that will become the fitting part, and in this state, electromagnetic shielding synthetic resin is filled into the cavity and solidified, and the metal plate is exposed in the fitting part. It is considered to be a sign of anger.

The electromagnetic shielding synthetic resin used in the present invention is a conductive filler such as gold powder, carbon powder, metal foil, metal string, carbon fiber, etc., mixed with polystyrene, styrene such as BS resin, etc. It is mixed with thermoplastic resins such as A-based resins such as polypropylene, polycarbonate-1, polytsunomide a3J, and polystyrene.

The metal plates used in the present invention include flat or letter-shaped iron, 111, nofluminium, alloys thereof, and those plated on the surface.

Next, the invention method will be explained using drawings.

FIG. 1 shows a cross section of a mold used in the method of the present invention.

In the figure, J3 and sign month 1.2 are the fixed side templates of the mold, respectively.
The temperature of the movable side mold (anti-C), the fixed side key V bit surface 3, the moving side key 1, and the stationary surface 4 are respectively set by the heat medium flow path 5, and the conductive filler is applied to the molded product surface by the heat medium in G. The temperature is controlled at an appropriate temperature of 60℃ or higher to prevent exposure. Code 7
This is a feature of the present invention, and is a metal plate inserted into the mold cavity, which serves as the molded product fitting part. This metal plate 7
Here, the filled synthetic resin with electromagnetic shielding properties is 'c'.
It is rapidly cooled and solidified to expose the conductive filler, and is cooled in advance to -40 to 20 DEG C. and inserted into the mold cavity so as to be in close contact with the metal plate 7.

In the present invention, using such a mold, first, an electromagnetic shielding synthetic resin that has been plasticized in the cylinder of an injection machine is filled into the mold cavity through the nozzle ridge part 8 of the mold. . At this time, the conductive filler is not exposed on the fixed side cavity surface and the moving side cavity surface due to the influence of the heat medium in the heat medium flow path 5.6, but is exposed on the surface of the metal plate 7 which is in a low temperature state, and the conductive filler The electromagnetic shielding synthetic resin solidifies in a state where the plate 7 and the conductive filler are electrically connected.

Figure 2 (a) shows a cross section of an electromagnetic shielding case formed by fitting the molded product 9.10 with the exposed metal plate in contact with the metal plate 7.7' in the fitting part formed in this way. , an enlarged cross section of the fitting portion is not shown in FIG. 2(b). Figure 2 (b
J: The conductive filler in the sea urchin molded product 9 is electrically connected to the metal plate 7, and the gold rA plate 7 is connected to the other molded product 1.
The metal plate 7' of the molded product 10 is in contact with the metal plate 7' of the molded product 10.
' is electrically conductive with the conductive filler in the molded product 10, so the fitted part of the electromagnetic shielding case is electrically conductive as a whole, and the conductive filler is exposed on the case surface. Because it is smooth in appearance and conductive, it does not get charged by contact with the iJ3.

[Embodiment J of the invention Next, embodiments of the present invention will be explained.

EXAMPLE A cold 7JIL plated iron plate was inserted into a mold cavity serving as a fitting part so that the temperature a at the time of insertion was 5'G. In this condition tA (゛, the injection pressure is 900k (1/c) from the nozzle tedge part of the mold, the resin temperature is 230℃, the line 1'1
It was filled with an electromagnetic shielding synthetic resin made of ABS resin containing 40% by weight of brass fibers.

J3 gold W (warm stone has a surface temperature of 75 on the fixed side)
The surface temperature of the moving side cavity was adjusted to 70°C. The molding time was 18 seconds for injection and 60 seconds for cooling in the upper case, and 16 seconds for injection and 55 seconds for cooling in the lower case.

In this way, Te+['300111m, length 400+n
m, height 200 vlm, wall thickness 3 mm upper case, width 300 mm, length 400111111. Height 150I
A lower case with a wall thickness of 3tIIIn was manufactured, a DC motor was built into these molded products, and the upper and lower cases were fitted together. After that, rotate the DC motor,
The noise radio waves generated from the brush were caught by a tie ball antenna C at three positions outside the case, and measured using a spectrum analyzer. The measurement results were as shown in the graph in Figure 3 (a). - Electromagnetic shielding properties An electromagnetic shielding case was manufactured in the same manner as in the example except that no metal plate was used during molding of the synthetic resin. The noise radio waves were measured by incorporating a motor.The measurement results are shown in Figure 3 (b).
) was not shown in the graph.

As is clear from this graph, it was confirmed that the electromagnetic wave shields I to C' of the examples had small miscellaneous radio waves and had good electromagnetic wave shielding of 11 floors.

[Effects of the Invention] As explained above, according to the method of the present invention, the fitting part? 1
``'3!) Since the electromagnetic wave shielding case with an insulating surface can be created, there is no need for secondary processing of the molded product, and an electromagnetic wave shielding case with a large electromagnetic shielding effect can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the mold used in the method of the present invention, Fig. 2 is a cross-sectional view of the mold used in the method of the invention. b) is an enlarged sectional view of the I+X junction in Fig. 2(a), and Fig. 3(a)
Graph C shows the electromagnetic shielding performance of the electromagnetic shielding case obtained by the method of the present invention and the electromagnetic shielding case obtained by the conventional method. '1...Fixed side template 2...
・・・・・・Moving side template 3・・・・・・・・・・・・
Fixed side: Y side 4...Moving side kick 5.6...Heat medium flow path 7.7'...Metal plate 9.10...・Articles representative Patent attorney Satoshi Suyama - Figure 1 No. ? Figure (d) (b) Figure 3 (a) Canter ridge size 2 mark fLfu Ml-1!

Claims (3)

[Claims] (1) Electromagnetic shielding property When manufacturing an electromagnetic shielding case made by fitting two or more molded products made of synthetic resin, metal is placed inside the mold cavity of the part that becomes the fitting part of the molded products. Insert the board and in this state C key 1
7. A method for manufacturing an electromagnetic shielding case characterized by manufacturing a molded product having a metal plate exposed at the joint. (2) The method for manufacturing an electromagnetic wave shielding case according to claim 1, characterized in that the surface temperature of the mold is maintained at 60° C. or higher, and an electromagnetic wave seeding synthetic resin is provided in the cavity. (3) The metal plate is pre-cooled with N1 to 1/IO~20℃.
A method for manufacturing an electromagnetic shielding case according to claim 1 or 7iS2.