JP3437793B2 - Electromagnetic wave shield plate - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic wave shield material that shields electromagnetic waves generated from a high frequency power source and an electromagnetic wave source. In particular, the present invention relates to an electromagnetic wave shield plate that is required to have optical transparency and electromagnetic wave shielding properties.

[0002]

2. Description of the Related Art In recent years, various kinds of electric equipment and electronic equipment have come to be used, but along with this, electromagnetic noise interference such as conduction noise and radiation noise is also increasing. In particular, as a measure against radiated noise, it is necessary to electromagnetically insulate the space, so the housing is made of a metal body or a highly conductive body, a metal plate is inserted between the circuit boards, or a cable is used. Methods such as winding with metal foil are used. With these methods,
The electromagnetic wave shielding effect of circuits and power blocks can be expected, but the front of electronic displays such as CRTs and PDPs, doors,
It has been difficult to apply when the glass surface of the window or the like is required to have light transmittance.

Various proposals have been made to improve this point. As one of the methods, a method of forming a thin film conductive layer by vapor-depositing a metal or a metal oxide on a transparent substrate has been proposed as a method of achieving both electromagnetic wave shielding properties and light transmission properties. However, this method has insufficient electromagnetic wave shielding properties. That is, when the thickness of the conductive layer is such that transparency can be maintained (100 to 2000 angstroms), the resistance of the conductive layer is large and the electromagnetic wave shielding property is insufficient. Further, an electromagnetic wave shield material in which a good conductive fiber is embedded in a transparent substrate has also been proposed. However, in this electromagnetic wave shielding material, in order to enhance the electromagnetic wave shielding effect, it is necessary to increase the thickness of the fiber or increase the fiber density, and as a result, the light transmission becomes insufficient. .

On the other hand, Japanese Patent Laid-Open No. 10-41682 discloses an electromagnetic wave in which a copper foil is adhered to a transparent base material with an adhesive and the copper foil is etched in a photolithography process to form a grid pattern of the copper foil. Shielding materials have been proposed.
This electromagnetic wave shielding material has a well-balanced optical transparency and electromagnetic wave shielding property due to the opening area of about 90% and the good conductivity of the copper foil, but there is a problem in its manufacture. It was That is, about 90% of copper is dissolved and removed by wet etching and photoresist is discarded, which causes a problem that a large amount of waste is generated. Naturally, a large amount of waste not only affects the cost, but also adversely affects the environment.
The improvement is required. In addition, since this electromagnetic wave shield material uses a thin foil, when it is used as a large area shield material, it must be handled with extreme care.
In PDP use, glass use, etc., there was a problem in handling.

[0005]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems in the prior art. That is, the object of the present invention is to achieve both light transparency and electromagnetic wave shielding properties, and at the same time, the amount of the photosensitive curable resin and the conductive member to be discarded at the time of production is extremely small, and the electromagnetic wave capable of being further thinned. Ru near providing an electromagnetic wave shielding plate using <br/> the shielding material.

[0006]

The electromagnetic wave shield of the present invention
Plate, transparent to at least one surface of the support film, on the light-transmitting conductive electromagnetic shield layer is provided with a wave shielding material the electromagnetic wave shielding layer of the antireflection layer is set on one side
The transparent electromagnetic wave shielding layer has a laminated structure in which a striped transparent support plate is adhered , and the electromagnetic wave shield layer includes a conductive part having a striped pattern formed of a conductive member and a conductive line forming the conductive part. br /> that you characterized that is configured of a light transmitting portion and formed of a cured product of the divided photosensitive curable resin Te.

[0007]

[0008]

[0009]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described with reference to the drawings. FIG. 1 is a schematic perspective view of an example of an electromagnetic wave shield material used in the present invention. On the transparent support film 1, a light-curable photosensitive cured resin layer 2 is provided. The photosensitive cured resin layer includes a conductive portion 21 formed of linear, mesh-shaped or lattice-shaped conductive lines, and a light transmission portion 2 formed of a photosensitive cured resin divided into geometric patterns by the conductive lines of the conductive portions.
It is composed of 2 and. 2 is a schematic cross-sectional view of an example of the electromagnetic wave shield plate of the present invention, in which the electromagnetic wave shield material 10 of FIG. 1 is attached to one surface of the transparent support plate 3 with an adhesive layer 4 interposed therebetween. There is. An antireflection layer 5 is provided on the other surface of the transparent support plate.

In the present invention , the transparent support film used for the electromagnetic wave shielding material may be any transparent support film having light transmittance. Preferably, polyethylene terephthalate (hereinafter,
Abbreviated as "PET"), polyolefins such as polyethylene and polypropylene, ethylene-
Vinyl-based resins such as vinyl acetate copolymer (EVA), polyvinyl chloride, polyvinylidene chloride and polystyrene, acrylic resins (including copolymers), triacetyl cellulose (hereinafter abbreviated as "TAC"), polyether monkey Examples include phones, polycarbonates, and polyimides. Among them, PET, TAC and polycarbonate are preferable, and PET and TAC are most preferable, from the viewpoints of transparency, heat resistance, cost and handleability.

In the present invention, the thickness of the transparent support film is preferably in the range of 5 to 200 μm, because if it is thin, the handleability is poor, and if it is thick, the light transmittance is reduced. More preferably 10 to 100 μm, most preferably 25 to 75 μm
The range is m.

An electromagnetic wave shield layer having a light transmitting property is provided on one or both sides of the transparent support film.
The electromagnetic wave shield layer is composed of a stripe-shaped conductive portion formed of a conductive member and a light transmitting portion made of a cured product of a photosensitive curable resin divided by a conductive line forming the conductive portion. . This electromagnetic wave shield layer can be formed, for example, as follows.

That is, first, a photosensitive curable resin layer having light transmittance is formed on one surface of the transparent support film. The composition of the photosensitive curable resin has an oligomer containing an unsaturated group, a reactive diluent, and a photopolymerization initiator that absorbs light energy to generate an active species as a basic component, In the present invention, any material can be used as long as it has light transmittance after being cured. For example, epoxy acrylate, a radical polymerization resin mainly composed of an oligomer having an acryloyl group such as urethane acrylate, and a photocationic polymerization type resin mainly composed of an epoxy compound such as an alicyclic epoxy compound are typical ones. Examples thereof include polyvinyl cinnamate type resist, rubber type resist (for example, polybutadiene mixed with a small amount of bisazide compound), novolac resin-azide type resist and the like.
The photosensitive photocurable resin layer may be formed by coating a photosensitive curable resin on a transparent support film, or may be formed by laminating a film of the photosensitive curable resin. The thickness of the photosensitive photocurable resin layer is preferably in the range of 5 to 50 μm, more preferably 10 to 40 μm.

Next, the photosensitive curable resin layer formed as described above is irradiated with electromagnetic waves to be pattern-exposed.
The pattern exposure by electromagnetic wave irradiation may be carried out by any method, but preferably, pattern exposure is carried out with ultraviolet rays or the like using a photomask having a geometric pattern of a desired shape. As a result, the exposed portion of the photosensitive curable resin layer is cured to form a light transmitting portion having a desired geometrical pattern made of a cured product of the photosensitive curable resin. Geometric patterns include parallel line patterns, triangles, squares, hexagons,
Any shape such as a circular or elliptical pattern may be used.

Then, the photosensitive curable resin in the unexposed portion of the photosensitive curable resin layer is removed by etching.
The etching treatment can be carried out using a known etching treatment liquid, for example, an alkaline solution such as an aqueous solution of sodium carbonate or a solvent such as methanol, ethanol, methyl ethyl ketone or acetone.
As a result, the photosensitive curable resin in the uncured portion is removed, and linear groove portions having a striation pattern such as a linear shape, a mesh shape, or a lattice shape are formed.

Then, a conductive member is inserted into the formed groove to form a conductive portion. As the conductive member, any member can be used as long as it has conductivity and can fill the groove.
It is preferable to use a resin paste that exhibits viscosity when filling the groove and has the property of being curable after filling, specifically, a resin paste having curability and conductivity, and an energy ray curing type having conductivity. Examples include resins. More preferably, a thermosetting resin paste such as an epoxy resin or a phenol resin, or a liquid ultraviolet curable resin paste can be used. To impart conductivity, the resin itself may have conductivity, or metal powder such as gold, silver, copper, nickel, iron, ferrite, magnetite, carbon, or conductive fine powder such as conductive titanium oxide. Dispersing in a resin is also a preferable form. The most preferable one is a low resistance metal powder such as silver, copper or nickel or a carbon powder dispersed in a thermosetting resin or an energy ray curable resin.

It is preferable to insert a conductive member such as a conductive paste into the groove using a blade coater or the like. When a curable conductive member is used as the conductive member, the conductive member may be cured by heat or energy rays to form the conductive portion. That is, when the binder component of the conductive member is thermosetting, it can be heated, and when it is ultraviolet curable, it can be irradiated with ultraviolet rays to be cured.

In the electromagnetic wave shield plate of the present invention, the conductive portion formed as described above preferably has a width of a conductive line forming the conductive portion of 5 to 100 μm, more preferably 5 to 50 μm. Optimally 10-40
It is in the range of μm. The light transmission area ratio per unit area of the photosensitive cured resin layer is preferably 80% or more, more preferably 90% or more. The light transmission area ratio is, for example, (500) ² / when the light transmission portion is a square having a side of 500 μm and the width of the conductive line is 25 μm.
(500 + 12.5 × 2) ² = 90.7%.

[0019] photosensitive curing resin layer surface of the electromagnetic waves shielding material
Preferably, the provided contact Chakuzaiso. As the adhesive used for the adhesive layer, any known adhesive such as pressure-sensitive adhesive (adhesive) and thermosetting adhesive can be used. For example, acrylic adhesive layer To
It is preferably provided such that the thickness after drying is 5 to 30 μm.

The electromagnetic wave shield plate of the present invention can be produced by adhering the above electromagnetic wave shield material to a transparent support plate. For example, the electromagnetic wave shield layer of the electromagnetic wave shield material may be attached to the transparent support plate via an adhesive layer. As the transparent resin plate, for example, one made of acrylic resin is preferably used. The transparent resin plate is
It can be used with an appropriate thickness, but with a thickness of 0.1-5 mm
Those having a thickness of 1 to 3 mm are particularly preferable.

[0021] Oite the electromagnetic wave shielding plate of the present invention, the antireflection layer is preferably provided on the back surface of the transparency support plate. The antireflection layer is formed by alternately laminating two or more layers having a high refractive index and a low refractive index such that the outermost surface layer is a low refractive index layer. As a material of the layer having a low refractive index, MgF
As a material for a layer with a high refractive index such as SiO ₂ and SiO ₂ , TiO 2 is used.
₂ , ZrO _{2 and the} like. Usually, these materials are laminated by a vapor phase method such as vapor deposition or sputtering, or a sol-gel method. The thickness of the antireflection layer is preferably in the range of 1 nm to 5 μm.

In the above description, the case where the electromagnetic wave shield layer is formed on one surface of the transparent support film has been described. However, another electromagnetic wave shield layer may be provided on the other surface of the transparent support film in the same manner as above. it can.

[0023]

EXAMPLES The present invention will now be described in more detail with reference to examples. Example 1 An ultraviolet curable resin having the following composition was applied to a transparent PET film having a thickness of 75 μm, and a photoresist layer having light transmittance was formed so that the thickness after drying was 25 μm. (Ultraviolet curable resin) Urethane acrylate oligomer 9 parts by weight Neopentyl acrylate 2 parts by weight Ethylene glycol diacrylate 1.5 parts by weight Trimethylol propane triacrylate 2.5 parts by weight Benzophenone (photopolymerization initiator) 0.3 parts by weight The exposed photoresist layer was subjected to pattern exposure through a lattice-shaped photomask, and the exposed portion of the photoresist layer was cured to form a light transmitting portion having a square geometric pattern of 500 μm on a side. Then, an uncured portion was removed by performing an etching treatment using a 1% sodium carbonate aqueous solution to form a groove portion having a line width of 25 μm. On the other hand, a conductive paste having the following formulation was inserted into the groove with a blade coater and heated at 120 ° C. for 10 minutes to be cured to obtain an electromagnetic wave shield material of the present invention. The light transmission area ratio per unit area of the obtained electromagnetic wave shielding material was 91%.

Next, a thickness of 20 is applied to the cured photoresist surface.
After forming a μm acrylic pressure-sensitive adhesive layer, a 2 mm thick transparent acrylic plate was attached. Then, on the other surface of this acrylic plate, a PET film having a film thickness of 188 μm that had been subjected to antireflection treatment was attached via an acrylic adhesive layer to form an electromagnetic wave shield plate.

[0025] (Conductive paste prescription) Epoxy resin (EOCN-1020-65,     Made by Nippon Kayaku Co., Ltd.) 13 parts by weight NBR (CTBN1008-SP, Ube Industries, Ltd.) 1.8 parts by weight Resol phenolic resin (MH700,     Made by Shin Nippon Rika Co., Ltd.) 1.2 parts by weight Copper powder (average diameter: 1 μm) 78 parts by weight Carbon (MA-100, manufactured by Mitsubishi Chemical Corporation) 1 part by weight MEK / toluene 5 parts by weight

Example 2 In the same manner as in Example 1, a transparent photoresist film having a thickness of 50 μm was formed with a light-transmitting photoresist layer so that the thickness after drying was 20 μm. This photoresist layer is subjected to pattern exposure through a lattice-shaped photomask to cure the exposed portion of the photoresist layer and then 60
A light transmitting portion having a rectangular geometric pattern of 0 × 400 μm was formed. Then, an uncured portion was removed by performing an etching treatment using a 1% sodium carbonate aqueous solution to form a groove portion having a line width of 25 μm.

On the other hand, a conductive paste having the following composition was inserted into the groove by a blade coater, and the paste was heated at 120 ° C. for 10
It was heated and cured for a minute to obtain the electromagnetic wave shielding material of the present invention. The light transmission area ratio per unit area of the obtained electromagnetic wave shielding material was 90%.

Next, a thickness of 2 is applied to the cured photoresist surface.
After forming a 0 μm acrylic pressure-sensitive adhesive layer, the thickness is 2 mm
I attached the transparent acrylic plate. On the other side of the acrylic plate,
A PET film having a thickness of 188 μm and subjected to antireflection treatment was attached via an adhesive layer to form an electromagnetic wave shield plate.

[0029] (Conductive paste prescription) Epoxy resin (EOCN-1020-65,     Made by Nippon Kayaku Co., Ltd.) 13 parts by weight NBR (CTBN1008-SP, Ube Industries, Ltd.) 1.8 parts by weight Resol phenolic resin (MH700,     New Nippon Rika Co., Ltd.) 1 part by weight Nickel powder (average diameter: 2 μm) 78 parts by weight Carbon (MA-100, manufactured by Mitsubishi Chemical Corporation) 1.2 parts by weight MEK / toluene 5 parts by weight

Example 3 A transparent PET film having a thickness of 75 μm was formed with a photoresist layer having a light-transmitting property so that the thickness after drying was 25 μm in the same manner as in Example 1. This photoresist layer was subjected to pattern exposure through a mesh-like photomask, and the exposed portion of the photoresist layer was cured to form a light transmitting portion having a regular hexagonal geometric pattern with a diagonal diameter of 600 μm. Then, etching treatment was performed using a 1% sodium carbonate aqueous solution to remove the uncured portion and form a groove portion having a line width of 30 μm.

On the other hand, the conductive paste used in Example 2 was inserted into the groove by a blade coater, and 120
It was heated at 10 ° C. for 10 minutes to be cured to obtain the electromagnetic wave shielding material of the present invention. The light transmission area ratio per unit area of the obtained electromagnetic wave shielding material was 91%.

Next, a thickness of 2 is applied to the cured photoresist surface.
After forming a 0 μm acrylic pressure-sensitive adhesive layer, the thickness is 2 mm
I attached the transparent acrylic plate. On the other surface of this acrylic plate, a PET film having a film thickness of 188 μm that had been subjected to antireflection treatment was attached via an adhesive layer to form an electromagnetic wave shield plate.

Example 4 In the same manner as in Example 1, a transparent PET film having a thickness of 50 μm was formed with a light-transmitting photoresist layer so that the thickness after drying was 15 μm. This photoresist layer was subjected to pattern exposure through a mesh-shaped photomask, and the exposed portion of the photoresist layer was cured to form a light transmitting portion having a regular triangular geometric pattern with a base of 500 μm. Then, an uncured portion was removed by performing an etching treatment using a 1% sodium carbonate aqueous solution to form a groove portion having a line width of 20 μm. On the other hand, an ultraviolet curable conductive paste having the following formulation was inserted into the groove by a blade coater and irradiated with ultraviolet rays to be cured to obtain an electromagnetic wave shield material of the present invention. The light transmission area ratio per unit area of the obtained electromagnetic wave shielding material was 92%.

Next, a thickness of 2 is applied to the cured photoresist surface.
After forming a 0 μm acrylic pressure-sensitive adhesive layer, the thickness is 2 mm
I attached the transparent acrylic plate. On the other surface of this acrylic plate, a PET film having a film thickness of 188 μm that had been subjected to antireflection treatment was attached via an adhesive layer to form an electromagnetic wave shield plate.

[0035] (UV curable conductive paste formulation) Urethane acrylate oligomer 9 parts by weight Neopentyl acrylate 2 parts by weight 1.5 parts by weight of ethylene glycol diacrylate 2.5 parts by weight of trimethylolpropane triacrylate Benzophenone (photopolymerization initiator) 0.3 parts by weight Silver powder (average diameter: 3 μm) 82 parts by weight

[0036]

Comparative Example 1 An indium oxide layer was provided as a first layer (15 nm) and a third layer (20 nm) on one surface of the transparent PET film having a thickness of 50 μm used in Example 2, and a silver thin film having a thickness of 14 nm was used as a second layer. The layer was formed by a sputtering method under vacuum to obtain a transparent conductive film. An acrylic pressure-sensitive adhesive layer having a thickness of 20 μm was formed on the other surface of this transparent conductive film, and the acrylic pressure-sensitive adhesive layer used in Example 1 was adhered to obtain a comparative electromagnetic wave shield plate.

Comparative Example 2 A conductive mesh (wire diameter: 43 μm) was prepared by electrolessly plating copper / nickel on a polyester core fiber on one surface of a transparent acrylic plate having a thickness of 2 mm and black-coating the surface with carbon black.
m, mesh size 200 mesh, thickness 66 μm), which was integrally molded using a light-transmitting electromagnetic wave shield sheet for comparison (manufactured by Nisshinbo Co., Ltd., trade name: Denji Sheet MA200-2).
0) was used as an electromagnetic wave shield plate for comparison.

The electromagnetic wave shielding properties and light transmission properties of the electromagnetic wave shielding plates or the electromagnetic wave shielding materials of Examples 1 to 4 and Comparative Examples 1 and 2 were measured. The results are shown in Table 1. Electromagnetic wave shielding property: spectrum analyzer TR-4172 (evaluation unit TR17301) manufactured by ADVANTEST
Was used to measure the shielding rate at 500 MHz. Light transmittance: The light transmittance at 400 to 700 nm was measured using a UVIDEC-670 type visible ultraviolet spectrophotometer manufactured by JASCO Corporation.

(Measurement result)

[Table 1]

[0041]

Since the electromagnetic wave shielding plate of the present invention has the above-mentioned constitution, it exhibits sufficient transparency and electromagnetic wave shielding property. Further, it has a simple structure and can be sufficiently thinned, and it can be suitably used for a large-area electromagnetic wave shield. Further, the electromagnetic wave shielding plate of the present invention, Saishi the production of the conductive portion of the striations pattern, since it does not require etching of the copper foil as in the prior art, the manufacturing operation is simple, waste The quantity is extremely small. Therefore, the electromagnetic wave shield plate of the present invention is excellent in terms of resource saving and also in terms of environment.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of an example of an electromagnetic wave shield material used in the present invention.

FIG. 2 is a schematic sectional view of an example of an electromagnetic wave shield plate of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Transparent support film, 2 ... Photosensitive curable resin layer, 3 ... Transparent support plate, 4 ... Adhesive layer, 5 ... Antireflection layer, 10 ... Electromagnetic wave shield material, 21 ... Conductive part, 22 ... Light transmitting part.

Continuation of the front page (56) References JP-A-10-41682 (JP, A) JP-A-10-161553 (JP, A) JP-A-10-188822 (JP, A) JP-A-11-346088 (JP , A) JP 63-282289 (JP, A) JP 10-335885 (JP, A) JP 5-251890 (JP, A) JP 2000-258922 (JP, A) JP 11 -344933 (JP, A) JP-A-4-175154 (JP, A) JP-A-11-121978 (JP, A) JP-A-11-87987 (JP, A) Actual Kaihei 3-97998 (JP, U) ) (58) Fields investigated (Int.Cl. ⁷ , DB name) H05K 9/00 G09F 9/00 B32B 1/00-35/00

Claims (3)

(57) [Claims] 1. At least one surface of the transparent support film,
Over the electromagnetic wave shielding layer of the electromagnetic wave shielding layer having optical transparency is provided electromagnetic waves shielding material, reflecting on one surface explosion
With a laminated structure in which a transparent support plate with a stop layer is attached
A magnetic wave shield plate , wherein the electromagnetic wave shield layer is composed of a stripe-shaped conductive portion formed of a conductive member and a light-curable cured resin divided by conductive lines forming the conductive portion. An electromagnetic wave shield plate comprising a transparent portion. 2. The conductive line forming the conductive portion has a width of 5 to 100 μm, and a light transmission area ratio per unit area of the electromagnetic wave shield layer is 80% or more. Electromagnetic wave shield plate . 3. The electromagnetic wave shield plate according to claim 1, wherein the conductive portion contains a curable resin and conductive fine powder.