JP2000236194A - Electromagnetic shielding filter and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily bond adhesive to the adhered to a plastic base material and a display surface by bonding a transparent base material, where an adhesive layer is installed at a rear face and a conduction material, where a mesh-like geometric graphic is formed by means of chemical etching work via adhesive. SOLUTION: For forming a mesh-like geometric graphic in a conduction material, it is advantageous to generate it by a microlithography in terms of precision and the efficiency of circuit work. When the conduction material is formed of copper and a bonding face with a transparent base material is blacking-processed, contrast becomes high. A plastic film is most preferable as a transparent base material by taking into consideration chemical resistance, handling property and cost at chemical etching of the conduction material. The adhesion property of the transparent base material and the conduction material can be improved by a primer processing on the surface of the transparent base material. Composition flowing at a prescribed temperature is desirable as adhesive for bonding the transparent base material and the conduction material. An adhesion resin layer is made to flow by heating and pressurizing the base material and the conduction material, and they can be bonded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a CRT, a PDP,
The present invention relates to an electromagnetic wave shield filter for shielding electromagnetic waves generated from the front of a display such as an EL, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, society has become increasingly sophisticated, and a display is one of the indispensable elements for attaining this. It is widely used not only for TV but also for word processors, personal computers, analytical instruments, game machines, in-car monitors, and the like. In addition, each of them has a remarkable increase in size.
On the other hand, electromagnetic waves radiated from electric and electronic instruments are becoming a major social problem. Electromagnetic waves may cause noise or malfunction in surrounding equipment. Since computers are frequently used to increase the number of electronic devices themselves and to control each device, a failure may easily occur, which may lead to a serious accident. It has also been pointed out that there is a risk of health problems for the human body. Legal regulations have already been set in Europe and the United States, and in Japan there are also self-regulations by manufacturers. As a method for shielding these electromagnetic waves, there are a method of making the device housing itself a metal body or a high conductor, a method of inserting a metal plate between circuit boards, and a method of winding a metal foil around a cable. However, for the electromagnetic waves radiated from the display surface, the above-mentioned method does not satisfy the most important function of “viewing” the display. Therefore, for shielding electromagnetic waves for a display, both electromagnetic shielding properties and transparency for obtaining visibility are required.

[0003] Various methods have been proposed as methods for achieving both electromagnetic shielding properties and transparency. In particular,
As disclosed in JP-A-41682 and JP-A-10-75087, a transparent plastic film and a conductive material are bonded together via an adhesive, and a geometric pattern is formed on the conductive material by a chemical etching process. It has been found that the method gives the best properties. However, when this method is applied to the surface of an adherend such as a display, the method requires heating and pressurizing the adhesive used for bonding the transparent substrate and the conductive material, and an adhesive having excellent fluidity is required. Must be used.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has as its object to provide an electromagnetic wave shielding filter which can be easily attached to an adherend such as a plastic substrate or a display surface. I do.

[0005]

That is, the present invention relates to an electromagnetic wave shielding filter comprising a transparent base material and a conductive material having a mesh-like geometric pattern formed by chemical etching, which are bonded together via an adhesive. An electromagnetic wave shield filter with a viscous (adhesive) adhesive layer provided on the back of the material, a process of bonding a transparent substrate and a conductive material with an adhesive, and forming a mesh-like geometric figure on the conductive material by chemical etching And a step of forming a viscous (contact) adhesive layer on the back surface of the transparent substrate.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The transparent substrate used in the present invention is not particularly limited, but a plastic film is most preferable in consideration of chemical resistance, handleability, cost, and the like when a conductive material is chemically etched. For example, polyethylene terephthalate, polyesters such as polyethylene naphthalate, polyethylene, polypropylene, polyolefins such as polystyrene, polyvinyl chloride, vinyl resins such as polyvinylidene chloride, polycarbonate,
A film made of an acrylic resin or the like can be given. The thickness of the film is preferably 10 to 500 μm, and a polyethylene terephthalate or polycarbonate film is preferable in consideration of transparency, heat resistance, handleability, and the like. Further, by performing primer coating, corona treatment or plasma treatment on the surface of the transparent substrate, the adhesion between the transparent substrate and the conductive material can be improved.

In the present invention, the conductive material is not particularly limited, but may be copper, aluminum, nickel, iron,
Alloys of one or more of metals such as gold, silver, stainless steel, tungsten, chromium, and titanium can be used, but copper, aluminum, or copper is preferred in view of conductivity, ease of circuit processing, and price. Nickel is suitable,
It is preferable to use a metal foil having a thickness of 3 to 40 μm. When the thickness exceeds 40 μm, it is difficult to form a fine line width, and the viewing angle becomes narrow. If the thickness is less than 3 μm, the surface resistance increases and the electromagnetic wave seed effect is poor. It is preferable that the conductive material is copper and the surface to be bonded to the transparent substrate is subjected to blackening treatment because the contrast is increased. Further, it is possible to prevent the conductive material from being oxidized with time and discolored.

The adhesive for bonding the transparent substrate and the conductive material is not particularly limited, but is preferably a composition that flows at a predetermined temperature. Those which can be easily adhered by flowing the layer are preferable. The softening temperature of the polymer that forms these adhesive resin layers is preferably 150 ° C. or less from the viewpoint of handleability. The use environment is usually 8
Since it is 0 ° C. or lower, the softening temperature of the adhesive resin is most preferably 80 to 120 ° C. from the viewpoint of workability. On the other hand, although it depends on the resin system used, it is generally preferable that the weight average molecular weight of the polymer is 10,000 or more. Further, such a polymer preferably has a refractive index in the range of 1.40 to 1.70. This is because if the refractive index of the transparent substrate used in the present invention is different from that of the adhesive layer, the visible light transmittance is reduced.

As a material which flows into the adhesive layer by heating or pressurizing, the following thermoplastic resins or thermosetting resins are mainly used. Natural rubber (refractive index
n = 1.52), polyisoprene (n = 1.521), polyisobutene (n = 1.505-1.51), polybutene (n = 1.51)
3), (di) enes such as polyoxyethylene (n =
1.456), polyoxypropylene (n = 1.450), polyethers such as polyvinyl ethyl ether (n = 1.454), polyesters such as polyvinyl acetate (n = 1.467), polyvinyl propionate (n = 1.467),
Polyacrylonitrile (n = 1.52), polymethacrylonitrile (n = 1.52), polysulfone (n = 1.633),
Polysulfide (n = 1.6), phenoxy resin (n =
1.5-1.6), polymethyl acrylate (n = 1.472-
1.480), poly (meth) acrylates such as polyethyl acrylate (n = 1.469), polybutyl acrylate (n = 1.466), polymethyl methacrylate (n = 1.489). Also uses polyvinyl butyral, polyvinyl alcohol, polyvinyl acetate, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyvinyl chloride, epoxy resin, phenol resin, cresol resin, nitrile rubber, cyclized rubber, etc. can do. If necessary, two or more of these may be copolymerized, or two or more of them may be used as a blend.

Next, the above-mentioned transparent substrate and the conductive material are bonded together via the above-mentioned adhesive. The adhesive is applied to either the transparent substrate or the conductive material, or both. Its application,
The drying method is not limited as long as it is a known method. The thickness of the adhesive is 10 to 50 μm, more preferably 10 to 2 μm.
0 μm. The bonding method is not limited, but examples thereof include a pressing method, a roll laminating method, and an autoclave method. The roll lamination method is most preferable in consideration of mass productivity and economy.

The mesh-shaped geometric figures of the present invention include triangles such as equilateral triangles, isosceles triangles and right triangles, squares such as rectangles, rectangles, rhombuses, parallelograms and trapezoids,
(Regular) hexagon, (Regular) octagon, (Regular) dodecagon, (Regular)
The pattern is a combination of (positive) n-sided polygons such as icosagons, circles, ellipses, and stars, and these units can be used alone or in combination of two or more. From the viewpoint of electromagnetic wave shielding, a triangle is most effective, but from the viewpoint of visible light transmission, the aperture ratio increases as the number of (positive) n-gons increases for the same line width. From the point, the aperture ratio must be 50% or more and 60%
The above is more preferred. The aperture ratio is a percentage of the ratio of the area obtained by subtracting the area of the conductive material of the geometric figure drawn with the conductive material from the effective area to the effective area of the electromagnetic wave shielding film. When the area of the display screen is defined as the effective area of the electromagnetic wave shielding film, the display screen is a ratio that can be seen.

As a method for forming a mesh-like geometric figure on a conductive material, it is advantageous to produce the figure by a microlithographic method from the viewpoint of the precision and efficiency of circuit processing.
This microlithography includes photolithography,
There are an X-ray lithography method, an electron beam lithography method, an ion beam lithography method and the like, and in addition to these, a screen printing method and the like are also included. Among these, the photolithographic method is the most efficient in terms of its simplicity and mass productivity. Above all, a photolithography method using a chemical etching method is most preferable in terms of its simplicity, economy, circuit processing accuracy, and the like. The method using the microlithography method is to provide a photosensitive layer on the surface of a conductive material obtained by laminating a transparent substrate and a conductive material, and to expose and develop a mask having a mesh-shaped pattern formed on the photosensitive layer, In this method, a resist image is formed, the conductive material is etched to form a geometric pattern, and finally, the resist is peeled. Among the photolithographic methods, in addition to the chemical etching method, it is also possible to form a geometric figure by a method using electroless plating or electroplating, or a combination of electroless plating or electroplating and chemical etching.

The line width of the etching resist pattern is 10 to 5 from the viewpoint of facilitating formation of a good pattern.
0 μm, more preferably 10 to 3 μm.
0 μm. The line width of a geometric figure drawn with a conductive material is preferably 30 μm or less, and more preferably 20 μm or less. The line pitch is preferably in the range of 100 to 500 μm. Further, the line width is preferably narrower from the viewpoint of visible light transmittance as long as the line is electrically conductive. However, if the line width is too narrow, the production becomes difficult, so that the line width is preferably 10 μm or more. The larger the line pitch, the higher the aperture ratio and the higher the visible light transmittance, but the lower the electromagnetic wave shielding property. Therefore, the line pitch is preferably 500 μm or less. When the line pitch is complicated by a combination of geometric figures and the like, the area is converted into the area of a square on the basis of the repeating unit, and the length of one side is defined as the line pitch.

In the present invention, a tackifier is applied to the back surface of the transparent substrate. The method for applying the adhesive (contact) is not particularly limited, and examples thereof include a method of applying a pressure-sensitive adhesive to a transparent substrate in advance, and a method of performing the method after chemical etching. However, it is preferable to perform it after the completion of chemical etching in consideration of the penetration of the developer and the etching agent into the photosensitive layer and contamination. There is no limitation on the type of adhesive to be applied. Resins, 2
More than one kind of resin may be combined. Above all,
In the case of using an adhesive, an acrylic resin is preferable because the adhesiveness, glass transition temperature and the like can be easily set by molecular design. If necessary, a crosslinking agent, a tackifier, a plasticizer, and a filler may be added. Further, a material which is cured by heating or light irradiation or a water-soluble adhesive can be used. What is important is that the pressure-sensitive adhesive layer needs to be made to flow under pressure to easily adhere to an adherend such as a display surface. Therefore, the glass transition temperature of the adhesive
Considering that the paste is performed at around room temperature, -50 to 40
C. is preferred. It is more preferable that the temperature is -50 to 10C. Although the molecular weight depends on the resin system used, it is generally preferable to use those having a weight average molecular weight of 100,000 or more. When the molecular weight is less than 100,000, the cohesive force of the pressure-sensitive adhesive is too low, and there is a possibility that the adhesion to the adherend is reduced. The thickness of the adhesive layer to be applied is determined according to the desired adhesive strength, but is generally from 1 to 80 μm. The coating and drying method is not particularly limited, and a known method can be employed.
Providing a separator on the applied adhesive (contact) adhesive layer is preferable because adhesion of dust and dust can be prevented, and there is no time limit for sticking to an adherend. This is because when an adhesive is used, the molecular weight and the glass transition temperature of the polyester resin can be easily controlled in the same manner as the acrylic resin.
Additives, such as a crosslinking agent and a plasticizer, can also be compounded. The glass transition temperature of the adhesive is preferably from 60 to 90 ° C., and if it is higher than that, the heat flow temperature is undesirably high. As for the molecular weight, the weight average molecular weight is preferably from 1 to 100,000. If the weight-average molecular weight is less than 10,000, sufficient cohesion may not be obtained, or it may be difficult to apply uniformly in a solution. On the other hand, if it is larger than 100,000, the melt viscosity increases, and the workability deteriorates. Adhesive thickness is usually 5
２０20 μm.

This electromagnetic wave shield filter is used as an electromagnetic wave shield by attaching it to a transparent plastic or glass plate. Acrylic resin (n = 1.49) and polymethyl methacrylate resin (n
= 1.49), polycarbonate resin (n = 1.58), polyvinyl chloride resin (n = 1.54) and the like. The thickness of the plastic plate is preferably 0.5 mm to 5 mm from the viewpoint of protection, strength, and handleability of the display. Although glass has the disadvantage of being heavy, glass is preferable because of its excellent weather resistance, chemical durability, light transmission, and tentative heat resistance. There is no particular limitation on the method of sticking, and examples thereof include a method using a press method, a roll laminating method, and an autoclave method. The roll lamination method is most preferable in consideration of mass productivity and economy.

[0016]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. (Example 1) As a transparent substrate, an acrylic pressure-sensitive adhesive film (trade name, manufactured by Hitachi Chemical Co., Ltd .; HITALEX K330)
A release-treated polyester (trade name, manufactured by Unitika Ltd .; Embret SC25, thickness 25) was used as a separator on the pressure-sensitive adhesive layer of 3,25 μm PET base and pressure-sensitive adhesive thickness of 7 μm.
μm) was used. In addition, a saturated polyester resin (trade name, manufactured by Toyobo Co., Ltd .; Byron UR-140) was selected as an adhesive for bonding the transparent base material and the conductive material. Apply the above adhesive on the back side) using a coating machine and dry apply thickness 30 μm
And dried. The roughened surface of a 18 μm-thick rolled copper foil (trade name, manufactured by Japan Energy Co., Ltd .; BHY-02B-T, blackened matte surface), which is a conductive material, is provided on the adhesive side via the adhesive. So that 150
Roll lamination was performed at 200 ° C. and 200 N / cm to obtain a plastic film with a copper foil. Photolithographic process using a chemical etching method on the obtained plastic film with copper foil (resist film sticking-exposure-development-chemical etching-resist film peeling)
After that, an electromagnetic wave shielding filter having a copper grid pattern with a line width of 25 μm and a line interval of 250 μm was obtained.
Next, the separator on the side of the pressure-sensitive adhesive film on which the pressure-sensitive adhesive treatment was performed was peeled off, and a 3 mm-thick soda glass plate as an adherend was subjected to temperature: 25 ° C., pressure: 60 N / cm, and speed: 2 m /
It was pasted using a rubber roll under the conditions of minutes. The obtained electromagnetic wave shield showed some contamination by the drug around it, but it was in a range where there was no practical problem.

Example 2 One side of a release-treated polyester film (trade name, manufactured by Unitika Ltd .; Emblet SC25, thickness 25 μm) was placed on the PET side of the electromagnetic wave shielding filter prepared in Example 1 without the adhesive film. In addition, saturated polyester resin (trade name of Toyobo Co., Ltd .;
(Byron 24SS) is dried and roll-laminated with an adhesive film having a thickness of 25 μm at 120 ° C. and 50 N / cm. Then, the polyester film of the adhesive film is peeled off, and the thickness of the adherend is 3 mm.
100 ° C, pressure: 0.5MPa, 5
Pasted under the conditions of minutes. There was no practical problem in the obtained electromagnetic wave shield.

Example 3 Instead of the adhesive film of Example 2, a release-treated polyester film (Unitika Co., Ltd.)
Product name; Emblet SC25, thickness 25 μm), an acrylic pressure-sensitive adhesive (Tg: -45 ° C, Mw: 70)
A cross-linking agent: 25 phr of butylated melamine) is dried and then applied to a thickness of 8 μm to form a pressure-sensitive adhesive film. The electromagnetic wave shield filter prepared without the pressure-sensitive adhesive film of Example 1 and having a temperature of 25 ° C. , Pressure: 60N
/ Cm, speed: 2 m / min, using a rubber roll. Next, the polyester film of the pressure-sensitive adhesive film was peeled off, so that 100
C., pressure: 0.5 MPa, for 5 minutes. There was no practical problem in the obtained electromagnetic wave shield.

(Comparative Example) The PET side and the soda glass plate of the electromagnetic wave shielding filter prepared without providing the adhesive film of Example 1 were autoclaved through an EVA sheet (trade name: R5011 manufactured by Sekisui Chemical Co., Ltd., thickness: R5011: 400 μm). Bonding at 150 ° C, 0.5MPa, 30MPa
Severe conditions were required compared to the minutes and the examples.

[0020]

As described above, in the electromagnetic wave shielding filter, the side which is not in contact with the conductive material as the transparent substrate is subjected to the adhesive (contact) processing, so that it can be easily applied to the adherend such as the display surface. As a result, it has become possible to provide an electromagnetic wave shield filter at low cost.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kazumi Nakamura 1150 Goshomiya, Oaza, Shimodate, Ibaraki Pref.Hitachi Kasei Kogyo Co., Ltd. F-term (reference) at Goshomiya Works of Chemical Industry Co., Ltd. 5E321 AA04 BB23 BB41 BB44 CC16 GG05 GH01 5G435 AA00 BB02 BB05 BB06 FF00 GG33 HH12 KK07

Claims (4)

[Claims] 1. An electromagnetic wave shielding filter comprising a transparent base material and a conductive material having a mesh-like geometric pattern formed by chemical etching and bonded to each other via an adhesive, to adhere (stick) to the back surface of the transparent base material. An electromagnetic wave shield filter provided with an agent layer. 2. The electromagnetic wave shielding filter according to claim 1, wherein the side of the conductive material that adheres to the transparent substrate is blackened. 3. The transparent substrate is a plastic film,
3. The electromagnetic wave shielding filter according to claim 1, wherein the conductive material is a copper foil. 4. A step of bonding a transparent substrate and a conductive material with an adhesive, a step of forming a mesh-like geometric pattern on the conductive material by chemical etching, and a step of attaching a viscous (adhesive) adhesive to the back surface of the transparent substrate. A method for manufacturing an electromagnetic wave shield filter, comprising a step of forming a layer.