JPH02110999A - Conductive net for electromagnetic shielding - Google Patents

Abstract

PURPOSE:To obtain an electromagnetic shielding conductive net which is uncombustible, lightweight, and low in cost by a method wherein a chemical plating or an electroplating is performed onto a carbon fiber net, or a plating is performed onto a glass long fiber net through a silver or a copper mirror reaction, or a conductive paint is applied onto a glass long fiber, which is chemically or electrically plated. CONSTITUTION:A net, which is formed of carbon fibers of twill weave, leno weave, or plain weave, is chemically or electrically plated to be electrically conductive, and a single layer or a dual layer of copper, nickel, cobalt, gold, or the like or alloy is formed on the surface of the net. Or, a conductive layer excellent in adhesion is formed through a silver mirror or a copper mirror reaction on the surface of a net which is formed of glass long fibers of twill weave, leno weave, or plain weave. Or, conductive epoxy paint is applied to form a well attached conductive layer after a titanium coupling agent or a silane coupling agent is applied. Then, moreover a plating layer is formed through a conduction processing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a conductive net used for shielding (reflecting) electromagnetic waves.

[Conventional technology]

The housings of devices equipped with digital devices, such as personal computers, are often made of plastic molded products.

This plastic housing is non-conductive and has no free electrons, so it is transparent to radiated electromagnetic waves. Devices equipped with digital devices may leak electromagnetic waves radiated from internal devices to the outside and interfere with peripheral devices, or allow interference electromagnetic waves from other external devices to enter the device, causing interference. There is.

In order to prevent the leakage and intrusion of such unnecessary electromagnetic waves, the inner surface of the plastic housing is coated with conductive paint, metal spraying,
Conductive coatings are performed by chemical plating (also known as electroless plating), vacuum deposition, etc.

[Problem that the invention seeks to solve]

However, it is necessary to dissipate heat generated from ICs and other components used in devices equipped with digital devices to the outside of the device, and for this purpose, openings for heat dissipation are provided in the housing.

Of the conductive coatings mentioned above, excluding chemical plating,
Painting with conductive paint, metal thermal spraying with zinc, etc., and vacuum deposition with aluminum, etc. are all processed by spraying, so spraying from this heat dissipation opening will overspray the material and cause the back surface (outer surface) not to be coated with conductive coating. defile the

In order to prevent dirt on the back side, this heat dissipation opening is masked for protection, but this masking prevents the opening and its surroundings from being coated with conductive coating, and becomes a window for leakage and intrusion of unnecessary electromagnetic waves. Put it away.

Furthermore, plating has the disadvantage that it cannot be easily adopted due to its high cost.

The conventional measures to block the heat dissipation openings, which serve as windows for leakage and intrusion of unnecessary electromagnetic waves, have been to use metal nets or perforated metal plates (punched metal) to coat the periphery with a conductive coating. covering the opening in such a way that conductive contact can be made to the opening.

However, these metal nets and perforated thin plates that have an electromagnetic wave shielding effect have the following drawbacks.

(1) Because the material is hard, it is difficult to process it to match the shape around the opening of the plastic casing. Therefore, it is necessary to apply these metal shielding materials to the conductive coating surface that has been processed up to the periphery so that conductive contact is made around the entire periphery. It cannot be done, and an electrical blank is created.

■ This metal shielding material has a different coefficient of thermal expansion and expansion/contraction speed than the plastic molded product of the casing to which it is attached, so the bonded part (1) is likely to peel off.

(31 Cost is high.

[Means for solving problems]

In view of the above circumstances, the inventors of the present invention have conducted extensive research and have developed a method for using twill, twine, or plain weave nets made of carbon fibers or long glass fibers that are nonflammable and coated with a conductive coating on their surfaces. In this case, the present invention has been completed by discovering that the above-mentioned conventional problems can be solved.

That is, the present invention provides a conductive net for electromagnetic shielding made of carbon fibers which is subjected to chemical plating or electroplating, plating by silver mirror reaction or copper mirror reaction, or coating with conductive paint, and then further chemical plating or electroplating. This invention provides an electromagnetic wave shielding conductive net made of electroplated long glass fibers.

The present invention will be explained in detail below.

The net used in the present invention is made of carbon fibers or long glass fibers, and is made of twill weave, twine weave, or plain weave.

To impart conductivity to such a net (conductivity processing), a single layer or multiple layers of a single metal or alloy such as copper, nickel, cobalt, or gold is coated on the surface by conventional chemical plating or electroplating. This is done by forming a plating layer.

For example, a copper plating layer is formed by electroplating or chemical plating (also known as electroless plating) on a twill weave, twine weave, or plain weave net made of carbon fiber, and then a copper plating layer is formed by electroplating or chemical plating or other One plating method involves forming a plating layer of nickel, cobalt, gold, or the like to prevent the previous copper plating layer from oxidizing.

Alternatively, the formation of the copper plating layer may be omitted and a single plating layer made of a single metal such as nickel or an alloy may be formed for finishing.

Note that this conductive net can also be made by applying the conductive coating using the above-mentioned plating to the carbon fibers as they are, and then manufacturing a net using twill weave, twine weave, or plain weave.

However, the shielding effect will be higher if the carbon fiber net is woven first and then the net is processed to be conductive.

However, when long glass fibers are used as fibers, unlike carbon fibers, they are not conductors, so the current required for electroplating cannot be passed through them, and metal ions cannot be replaced during chemical plating, so the following steps must be performed before the conductive process: It is necessary to pre-process.

In other words, a twill weave, twine weave, or plain weave net made of long glass fibers is made by a reaction with a commonly known silver mirror or copper mirror.
First, a well-adhered conductive layer is formed on the surface of the glass fiber, or a titanium coupling agent or a silane coupling agent is applied to this net, and then a commonly known conductive paint such as epoxy is applied. This forms a conductive layer with good adhesion.

Thereafter, a plating layer is further formed thereon by the conductive process described above.

The conductive network of the present invention formed in this manner not only eliminates the conventional drawbacks as described above, but also has the following features.

(a) It is nonflammable.

(b) Since it is flexible, it can be attached to an R surface etc. with the entire circumference bonded.

(c) It can be easily cut with scissors.

(d) There is little expansion and contraction due to heat, so there is no peeling of the bonded parts.

(e) Lighter than metal shielding materials.

(f) Cheaper than metal shielding materials.

The present invention will be specifically explained below using Examples.

〔Example〕

Example 1 A 20 cm square mesh made by twilling carbon fibers was first degreased by alkaline immersion, electrolytically degreased, and solvent degreased with trichlorethylene vapor, then copper plated with the following bath composition and conditions, and after washing with water. Further, nickel plating was applied using the bath composition and conditions shown below, and then the conductive net for shielding electromagnetic waves of the present invention was obtained by washing with hot water.

Copper sulfate plating bath composition Sulfuric acid M Steel 460g Sulfuric acid 100g Chlorine ion 120g Water 2 yen 1 Conditions Liquid temperature 25℃ Current density 1 to 4 A/d m" Nickel sulfate plating bath composition Niracle sulfate 300g Ammonium chloride 30g Water Uric acid
30g water 2 strands Conditions Liquid Temperature 25°C Current density 0.6~L A/dm"Example 2 A 20cm square mesh made by twill weaving long glass fibers was first mixed with alcohol, nitric acid aqueous solution, and dichloride. After degreasing by immersing in a tin aqueous solution, a second liquid 25 (bywt.
) was added to the copper mirror treatment.

Soda carbonate 20g Water 2ml (2nd liquid) Rochelle salt 60g Formfuldet
After washing with 200 cc of water and 2 Yz of water, steel plating and nickel plating were applied in the same manner as in Example 1 to obtain a conductive net for shielding electromagnetic waves of the present invention.

Example 3 A two-component epoxy-based conductive paint containing copper powder was applied to the same long glass fiber net as in Example 2 using a roll coater, and after curing, copper powder was coated in the same manner as in Example 1. Plating and nickel plating were performed to obtain the electromagnetic shielding conductive net of the present invention.

Compounding base for two-component epoxy-based conductive paint containing copper powder Dosufznol A type epoxy resin 125 parts by weight Copper powder (particle size 5-15 μm) 200 parts by weight Ultrafine silica powder 30 parts by weight Toluene 50 Hardener by weight
Boreamide 100 parts by weight Toluene 55 parts by weight The conductive nets of Examples 1 to 3 thus obtained were cut with scissors, and a conductive nickel-based coating film for EMI shielding was applied around them. C that formed the product name 5bintron E-3063 manufactured by Tochemitron Co., Ltd.
Since it is flexible and is attached to the heat dissipation opening of the RT display using conductive double-sided adhesive tape containing nickel powder, it can be attached to the R surface with the entire circumference bonded. The reception was 5 to 6 μV lower than when no screen was attached.

〔Effect of the invention〕

The conductive network of the present invention is (&) Non-flammable.

(b) Since it is flexible, it can be attached to an R surface etc. with the entire circumference bonded.

(e) It can be easily cut with scissors.

(d) Since the expansion and contraction due to heat is small, There is no peeling.

(e) Lighter than metal shielding materials.

(f) Cheaper than metal shielding materials.

Therefore, it is suitable for shielding electromagnetic waves in heat dissipation openings of CRT displays, etc.

Patent applicant Shinto Paint Co., Ltd. Pasting part

Claims (2)

[Claims] 1. A conductive mesh for shielding electromagnetic waves made of chemically plated or electroplated carbon fiber. 2. Apply plating by silver mirror reaction or copper mirror reaction,
Or conductive mesh for shielding electromagnetic waves made of long glass fibers coated with conductive paint and then chemically or electroplated.