JPH0634475B2 - Manufacturing method of housing or its member excellent in electromagnetic wave shielding - Google Patents

Description

The present invention relates to a method of manufacturing a housing or a member thereof having excellent electromagnetic wave shielding properties.

In recent years, with the progress of plastics, the housings of electronic devices are being changed from conventional sheet metal products to plastic products. However, along with this, electromagnetic waves generated from electronic devices affect surrounding electronic devices, causing malfunctions and noise. This is because the plastic is essentially high in electrical insulation and poor in electromagnetic wave shielding ability. As a method to improve the drawbacks of such plastic housing,
It has been proposed to form a metal layer on the surface of the housing by vacuum vapor deposition, thermal spraying or the like, or to paint the housing with a conductive material. All of these are methods of imparting an electromagnetic wave shielding ability to the housing by secondary processing, and it is difficult to say that these methods are advantageous in terms of productivity.

The present invention provides a method for producing a casing having electromagnetic wave shielding ability or a member thereof by using a metal-plastic laminated plate which can be molded in the same manner as plastic, without secondary processing.

That is, the gist of the present invention is an electromagnetic wave shielding property characterized by forming a laminated plate of a thermoplastic synthetic resin and a metal exhibiting superplasticity at the forming temperature of the resin into a casing or its member by plastic working. It exists in the manufacturing method of the excellent housing or its member.

The present invention will be described in detail. In the method of the present invention, a laminate of a thermoplastic synthetic resin and a metal having superplasticity is used as a material. Examples of the thermoplastic synthetic resin include polyethylene, polypropylene, polyvinyl chloride acrylonitrile-styrene copolymer, addition polymer such as acrylonitrile-styrene-butadiene copolymer, polyester such as polybutylene terephthalate, nylon-6, nylon 6, and the like. Any of condensation polymers such as polyamides such as 6 and the like, polyamide amide imides and polycarbonates can be used. When the product is required to have flame retardancy, it is preferable to use polyester, nylon, or the like, which is easy to add a flame retardant. As the metal having superplasticity, a metal having superplasticity at the molding temperature of the synthetic resin which is integrally formed with the metal and constitutes the laminated plate is used. For example, if the synthetic resin to be laminated is polyethylene, a metal exhibiting superplasticity at about 100 ° C. and about 200 ° C. for polybutylene terephthalate or nylon-6 is used. When two types of resins are laminated, a metal that exhibits superplasticity at the molding temperature of a laminated plate made of only these resins is used. Examples of such metals include Pb-19% Sn, Sn-2% Pb, Sn-38.
% Pb and other Sn-Pb alloys, Sn-1% Bi, Sn-5% Bi, Bi-
Sn-Bi alloys such as 44% Sn, Zn-0.2% Al, Zn-0.
Examples thereof include Zn-Al alloys such as 4% Al, Pb-Cd alloys such as Pb-18% Cd, and Cd-Zn alloys such as Cd-16% Zn and Cd-27% Zn. Among them, Sn-Pb based alloys are preferable. In addition, in this specification, showing superplasticity is 20
It indicates that the elongation is 0% or more. Preferably, a superplastic metal showing an elongation of 500% or more, particularly 1000% or more at the forming temperature is used.

The laminated plate is obtained by laminating the above-mentioned thermoplastic synthetic resin layer on one side or both sides of the metal plate having the superplasticity as described above. The thickness of the laminate is arbitrary, but is usually 1 to 5
mm, especially 2 to 4 mm. Further, the thickness of the metal plate among them is determined by the elongation required for the laminated plate at the time of molding and the electromagnetic wave shielding ability required for the product casing,
Usually, it is 10 to 1000 μ. If the metal plate in the laminated plate is too thin, the elongation of the metal plate cannot follow this during plastic working of the laminated plate, and the metal plate easily breaks. Also, the thicker the metal plate, the better the electromagnetic wave shielding ability. The laminated plate can be manufactured according to a known method for manufacturing a metal-synthetic resin laminated plate.
For example, a thermoplastic synthetic resin plate and a metal plate are superposed on each other via an adhesive film and heated and pressed to be integrated. On this occasion,
If desired, the surface of the metal plate may be roughened or an adhesive may be kneaded into the synthetic resin plate. Further, an adhesive and a thermoplastic synthetic resin are melt-extruded in a sheet form from an extruder onto a metal plate continuously fed out from a coil, and then a pair of rollers are passed through to laminate the two by a continuous method for integrating them. Plates can also be manufactured. The laminated plate thus manufactured usually has a structure in which a synthetic resin is laminated on one side or both sides of a metal plate, but other structures can be used if desired. The case or the member thereof can be manufactured from the laminated plate according to a known method for manufacturing the case or the member thereof from the thermoplastic synthetic resin plate by plastic working. Preferably, a vacuum molding method in which a laminate heated to the molding temperature is fixed on the upper surface of the female mold, and then the closed space formed by the female mold and the laminated plate is decompressed to bring the laminated plate into close contact with the surface of the female mold, A pressure molding method is used in which pressure is applied to the laminated plate from the back to bring the laminated plate into close contact with the female mold. According to these methods, it is possible to mold only with an inexpensive female mold.

Since the plastic deformation rate of the superplastic metal is lower than that of the thermoplastic synthetic resin, it is preferable that the working rate of the laminated plate is considerably lower than the working rate of the thermoplastic synthetic resin plate. If the processing speed is too high, the metal in the laminated plate will not be able to follow this and will be broken. The breakage is likely to occur in a greatly stretched portion such as a corner portion of the housing. Even if a rupture occurs, the rupture is usually localized, and usually the metal is not completely divided into individual fragile pieces and the fragile pieces are bonded to each other and exist as an integral metal plate, so The shielding ability is maintained with almost no loss.

According to the method of the present invention, it is possible to easily manufacture a housing having a high electromagnetic wave shielding property in one step.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples as long as the gist thereof is not exceeded.

Example ADMER VE205 (adhesive film, product of Mitsui Petrochemical Industry Co., Ltd.) was overlaid on Kaidatsuku (manufactured by Tsutsunaka Plastics Co., Ltd., acrylic modified vinyl chloride resin plate, thickness 1 mm), and a superplastic alloy was further overlaid on it. Rolled sheet (60:40 tin and lead)
Of the above alloy, thickness 100 μ) were stacked and heated and pressed at 120 ° C. for 1 minute under a pressure of 1 kg / cm ² to bond them to obtain a laminated plate. The above laminated plate heated to 150 ° C. was placed with the metal surface facing upward in a mold having a recess of 60 × 60 × 21 mm and rounded upper edges and corners, and was pressurized with compressed air from the upper surface. The laminated plate was brought into close contact with the concave portion of the mold. The appearance of the resin surface of the obtained molded product was completely the same as that of the molded product itself. In addition, the metal surface of the molded product had cracks at some corners and part of the bottom surface, but it was such that it did not pose any problem in terms of electromagnetic wave shielding ability. This crack can be eliminated by adjusting the pressurization rate in compressed air.

Front Page Continuation (72) Inventor Nobuyuki Matsuzoe 1000 Kamoshida-cho, Midori-ku, Yokohama-shi, Kanagawa Sanryo Kasei Kogyo Co., Ltd. (56) Reference JP 57-91600 (JP, A) -195499 (JP, U) JP-B 56-13780 (JP, B2)

Claims (3)

[Claims] 1. An electromagnetic wave shielding property which is characterized in that a laminated plate of a thermoplastic synthetic resin and a metal exhibiting superplasticity at a molding temperature of this resin is molded into a casing or a member thereof by plastic working. Manufacturing method of housing or its components. 2. The method according to claim 1, wherein a vacuum forming method or a pressure forming method is used as the plastic working method. 3. A tin-lead superplastic alloy is used as a metal having superplastic performance.
The method according to item 2 or item 2.