JPS59178799A - Housing with excellent electromagnetic wave shielding property or method of producing same member - 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] The present invention features a housing with excellent electromagnetic shielding properties and a relates to the manufacture of the component.

In recent years, with the advancement of plastics, the housings of electronic devices are being replaced from conventional sheet metals to plastics. However, along with this, electromagnetic waves generated from electronic devices have affected surrounding electronic devices, causing malfunctions and noise. This is because plastic inherently has poor electrical insulation and poor electromagnetic shielding ability.

As a method to improve these drawbacks of plastic casings, it has been proposed to form a metal layer on the surface of the casing by vacuum deposition or thermal spraying, or to paint the casing with conductive material. . These are all methods of imparting electromagnetic shielding ability to the housing through secondary processing, and are far from being advantageous in terms of productivity.

The present invention provides a method for manufacturing a casing or a member thereof that has electromagnetic shielding ability without performing secondary processing by using a metal-plastic laminate that can be molded in the same manner as plastic.

That is, the gist of the present invention is to form a laminate of a thermoplastic synthetic resin and a metal that exhibits superplastic performance at the molding temperature of this resin into a casing by plastic processing. The present invention resides in a method for manufacturing a housing or its members with excellent shielding properties.

To explain the present invention in detail, in the method of the present invention, a laminate of a thermoplastic synthetic resin and a metal having superplastic properties is used as a material. Examples of thermoplastic synthetic resins include addition polymers such as polyethylene, polypropylene, polyvinyl chloride acrylonitrile-styrene copolymer, acrylonitrile-styrene-butadiene copolymer, polyesters such as polybutylene terephthalate, nylon-6, and nylon-2. Any of condensation polymers such as polyamide, polyamideimide, polycarbonate, etc., can be used. When flame retardancy is required for the product, it is preferable to use polyester, nylon, etc. that are easily blended with a flame retardant. As the metal having superplastic performance, there is used a metal that exhibits superplastic performance at the molding temperature of the synthetic resin that forms the laminate together with the metal. For example, if the synthetic resin to be laminated is polyethylene, a metal exhibiting superplastic performance at around /00'Q is used, and if the synthetic resin is polybutylene terephthalate or nylon-6, a metal exhibiting superplastic performance at around 200C is used. Furthermore, when two types of resins are laminated, a metal is used that exhibits superplastic performance at the temperature at which a laminate made only of these resins is formed. Such metals include pb-/%Sn, Sn, 2%Pb,
5n-Pb alloy such as Sn-Jg%Pb, Sn-/%
Bi, 5n-4%B11B soil-! ! 5n- such as %Sn
Bi-based alloy, Zn-0,2%Al, Zn-0,'1%
Zn-Al alloy such as A1, pl)-/, l'%C! d
Pb-Cd alloys such as, Cd-/&%Zn%Cd-
,! 7% Zn etc. C! Examples include d-Zn alloys. Among them, 5n-Pb alloy is particularly preferred. In addition, in this specification, "exhibiting superplastic performance" means 1.2o
It refers to showing an elongation of 0% or more. Preferably, a superplastic metal is used which exhibits an elongation of at least the SOO coefficient, especially at least 1004, at the molding temperature.

The laminate is made by laminating a thermoplastic synthetic resin layer as described above on one or both sides of a metal plate having superplastic properties as described above. The thickness of the laminate is arbitrary, but usually /~-
'a% Especially 2 ~ gu peep. However, the thickness of the metal plate is determined by the elongation required of the laminate during molding and the electromagnetic shielding ability required of the product casing, but is usually 10 to 100 θμ. If the metal plates in the laminate are too thin, the elongation of the metal plates will follow the plastic working of the laminate and the metal plates will easily break.

Further, the thicker the metal plate, the better the electromagnetic shielding ability. The laminate can be manufactured according to a known method for manufacturing metal-synthetic resin laminates. For example, a thermoplastic synthetic resin plate and a metal plate are stacked on top of each other with an adhesive film interposed therebetween, and heated and pressed to integrate them. At this time, if desired, the surface of the metal plate may be roughened or an adhesive may be applied to the synthetic resin plate. By a continuous method, adhesive and thermoplastic synthetic resin are melted and extruded from an extruder into a sheet onto a metal plate that is continuously fed out from a coil, and then passed between a pair of rollers to integrate the two. It is also possible to produce laminates. The laminate produced in this manner usually has a structure in which synthetic resin is laminated on one or both sides of a metal plate, but other structures may be used if desired. The casing or its members can be manufactured from a laminate according to a known method for manufacturing a casing or its members from a thermoplastic synthetic resin plate by plastic working. Preferably, a vacuum forming method is used in which a laminate heated to the molding temperature is fixed on the upper surface of the female mold, and then the pressure is reduced in the sealed space formed by the female mold and the laminate to bring the laminate into close contact with the surface of the female mold. A pressure molding method is used in which pressure is applied to the laminate from behind to bring the laminate into close contact with the female mold. According to these methods, molding can be performed using only an inexpensive female mold.

Furthermore, since the plastic deformation rate of superplastic metal is much smaller than that of thermoplastic synthetic resin, it is preferable that the processing speed of the laminate is considerably lower than the processing speed of thermoplastic synthetic resin. If the processing speed is too high, the metal in the laminate will not be able to follow this speed and will break. Fractures tend to occur in areas that are stretched significantly, such as at the corners of the housing. Even if a fracture occurs, it is usually localized, and the metal is usually not completely divided into individual fragments, but the fragments are interconnected and exist as a single metal plate, so electromagnetic waves Shield ability is maintained almost unimpaired.

According to the method of the present invention, a housing with excellent electromagnetic shielding properties can be easily manufactured in one step.

EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

Example: ADMER”J on Kaidak (manufactured by Tsutsunaka Plastic Industry ■, acrylic modified vinyl chloride resin plate, thickness/mm)
F220! (Adhesive film, Mitsui Petrochemical Industries ■
product), and on top of that, a rolled plate of superplastic alloy (602≠0 alloy of tin and lead, thickness iooμ),
A laminate was obtained by heating and pressurizing and adhering the material under a pressure of kg/cyd using i:zoC for 7 minutes. toxAox2/
Using rrrIn, place the above laminate heated to 1ROC with the metal side facing up in a mold having a concave portion with rounded upper edges and corners, and pressurize the laminate with compressed air from the top to mold the laminate. It was placed in close contact with the recess. The appearance of the resin surface of the obtained molded product was no different from that of the molded product of Kaidac itself. In addition, some of the metal surfaces of the molded products had cracks in the corners and parts of the bottom, but these did not cause any problems in terms of electromagnetic shielding ability. These cracks can be eliminated by adjusting the rate of pressurization with compressed air.

Patent applicant: Mitsubishi Chemical Industries, Ltd. Topura Co., Ltd. Representative Patent Attorney Hase - Others/names

Claims (3)

[Claims] (1) A casing with excellent electromagnetic shielding properties, characterized by forming the laminate of a thermoplastic synthetic resin and a metal that exhibits superplastic performance at the molding temperature of this resin into the casing or its components through plastic processing. or the manufacturing method of its parts. (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) The method according to claim 1, item 2, characterized in that a tin-lead based superplastic alloy is used as the metal having superplastic properties.