JP4378561B2 - Electromagnetic wave shielding transparent sheet and manufacturing method thereof - Google Patents

Description

【００７７】
図４、図５及び表１に示される結果から明らかなように、本発明のシートはシート抵抗値が高いにも関わらず、良好なシールド特性を有していることが明らかとなった。特に、ＰＤＰの放射ノイズで問題視されている周波数帯（３０〜３００ＭＨｚ）の電磁波が、顕著にシールドされることが明らかとなった。
【００７８】
実施例２
ＰＤＰの前面に、前記実施例１で作成した電磁波シールド透明シートを設置したところ、モアレが発生しなかった。更に、ＰＤＰとの対面角度を４５度ずらして設置しても、モアレが発生しなかった。このことから、本願発明によって、モアレ現象が軽減又は消失されることが明らかとなった
【００７９】
【発明の効果】
本願発明は、上述のような構成を有することによって、細線加工が可能となり、しかも、良好な透明性及びシールド特性を有するという優れた効果を奏する。特に、本願発明においては、低周波領域の電磁波が格段にシールド（遮蔽）されるという、従来技術からは予測できない有利な効果を奏する。
【００８０】
また、本願発明は、微細な細線加工が可能となったことで、モアレ現象が軽減又は消失するという効果も奏する。これによって、従来のような、モアレを解消するための角度の調整が必要なくなり、ＰＤＰ等の機種毎にバイアス角度の調整も不要となる。
【００８１】
更に、本発明のシートの製造に際しては、メッキ等の複雑な工程を必要せず、容易に、しかも、安易に電磁波シールド透明シートが得られるという利点も有する。また、厚さが薄くなったことにより、粘着フィルムとの貼り合わせの際の気泡かみ込みの問題が軽減されるという利点も有する。
【００８２】
本願発明の透明シートは、このような優れた物性を有していることから、ＰＤＰ等の電磁波発生機器からの電磁波シールド用として有用である。
【図面の簡単な説明】
【図１】図１は、パターンが正方形格子パターンである場合の構成を平面図で示した図面である。
【図２】図２は、シート抵抗値を算出するためのモデル回路を示した図面である。
【図３】図３は、（イ）〜（ニ）の各工程で処理されて得られる本発明のシートの構造を断面図で示した図面である。
【図４】図４は、本発明の実施例の電磁波シールド特性を示す図面である。
【図５】図５は、比較例の電磁波シールド特性を示す図面である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improved electromagnetic shielding transparent sheet and a method for producing the same. In particular, the present invention relates to an electromagnetic wave shielding transparent sheet for electronic information equipment such as a plasma display (PDP).
[0002]
[Prior art]
Electromagnetic waves emitted from various electronic information devices, and conversely, electromagnetic waves received from other worlds have become a problem as a factor causing malfunction of the devices.
[0003]
Various measures have already been proposed and implemented for measures to prevent device failures caused by these electromagnetic waves. For example, in an electronic information device such as a plasma display, since an electromagnetic wave emitted from the inside through the screen becomes an obstacle, a method of loading an electromagnetic shielding material on the screen is generally used. In such a case, the shielding material must not be opaque, and is required to be transparent and effectively shield electromagnetic waves.
[0004]
Conventionally, as an electromagnetic shielding member having transparency, a copper foil having a thickness of 10 to 40 μm is bonded onto a transparent substrate, and then patterned by a photolithography method, followed by etching to form a pattern on the sheet. Shield members have been proposed.
[0005]
However, the copper foil having the thickness as described above has good shielding properties, but there is a limit to thinning the pattern, and there are also problems such as a decrease in overall transparency and visibility.
[0006]
[Problems to be solved by the invention]
The main object of the present invention is to provide an electromagnetic wave shielding transparent sheet having good transparency and shielding properties and excellent in fine wire workability.
[0007]
[Means for Solving the Problems]
The present inventor has intensively studied with the main purpose of solving the above problems. As a result, by setting the thickness of the metal layer, the line width, the pitch width, and the ratio between the line width and the pitch width to a specific range, the electromagnetic wave has excellent transparency and shielding characteristics and excellent thin line workability. It has been found that a shield transparent sheet can be obtained, and further studies have been made to complete the present invention.
[0008]
That is, the present invention relates to the following matters.
1. An electromagnetic wave shielding transparent sheet having a conductive pattern comprising a metal layer on a transparent substrate, wherein the metal layer has a thickness of 0.01 to 1 μm.
2. 2. The electromagnetic wave shielding transparent sheet according to 1, wherein the line width (a) of the conductive pattern is 1 to 10 μm.
3. The electromagnetic wave shielding transparent sheet in any one of 1 or 2 whose pitch width (b) of an electroconductive pattern is 5-200 micrometers.
4). The electromagnetic wave shielding transparent sheet according to any one of 1 to 3, wherein a ratio (b / a) of a pitch width to a line width of the conductive pattern is 5 to 40.
5). The electromagnetic wave shielding transparent sheet according to any one of 1 to 4, wherein the opening ratio of the conductive pattern is 64 to 95%.
6). The electromagnetic wave shielding transparent sheet according to any one of 1 to 5, having a sheet resistance value of 0.08 to 50Ω / □.
7. The electromagnetic wave shielding transparent sheet according to any one of 1 to 6 obtained by sequentially performing the steps described in the following (A) to (D).
(A) forming a metal layer on one side of the transparent substrate by a thin film forming means;
(B) developing the metal layer by a photolithography method to expose a non-conductive pattern portion;
(C) a step of chemically etching the non-conductive pattern portion to dissolve and remove the metal layer;
(D) A step of peeling and removing the remaining resist of the conductive pattern.
8). The manufacturing method of the electromagnetic wave shielding transparent sheet | seat characterized by performing the process described in following (I)-(D) sequentially.
(A) forming a metal layer having a thickness of 0.01 to 1 μm on one side of the transparent substrate by a thin film forming means;
(B) developing the metal layer by a photolithography method to expose a non-conductive pattern portion;
(C) a step of chemically etching the non-conductive pattern portion to dissolve and remove the metal layer;
(D) A step of peeling and removing the remaining resist of the conductive pattern.
9. (I) A composite sheet having a shield layer made of the electromagnetic wave shielding transparent sheet according to any one of 1 to 7, (ii) an antireflection layer, and (iii) a near infrared cut layer.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be specifically described.
[0010]
Conductive pattern
The conductive pattern has a geometric shape in which openings having a certain shape are repeated vertically and horizontally, and has a metal layer made of a conductive metal.
[0011]
The shape of the opening is not particularly limited, and examples thereof include a square, a rectangle, 3 or 5 to 10 regular polygons, a circle, and a rhombus. Among these, a square shape is preferable because it is easy to achieve both transmittance and shielding performance.
[0012]
Here, the line width, the pitch width, the ratio of the pitch width to the line width, and the aperture ratio in the present invention will be described using a square lattice pattern as an example with reference to FIG.
[0013]
In FIG. 1, the opening B is formed of A having one of the copper patterns as a structural unit. a is a line width, which indicates the width of a line forming one side of the structural unit A. b is the pitch width and indicates the length of one side of the structural unit A. The ratio of the pitch width to the line width is represented by b / a.
[0014]
The aperture ratio (%), the line width and the pitch width are in the relationship of the following formula 1.
[0015]
Formula 1: Opening ratio (%) = 100 × (b−a)²/ B²
In the present invention, the line width (a) of the conductive pattern is 1 to 10 μm, preferably 1 to 7 μm, more preferably 2 to 5 μm. If the line width is too large, it is not preferable in terms of moire interference and light transmittance, and if it is too small, it is not preferable in terms of shielding characteristics.
[0016]
The pitch width (b) of the conductive pattern is 5 to 200 μm, preferably 5 to 150 μm, and more preferably 10 to 100 μm. If the pitch width is too large, it is not preferable in terms of shielding characteristics, and if it is too small, it is not preferable in terms of light transmittance.
[0017]
The ratio (b / a) of the pitch width to the line width of the conductive pattern is 5 to 40, preferably 10 to 30, and more preferably 15 to 25. If the ratio of the pitch width to the line width is too large, it is not preferable in terms of shielding characteristics, and if it is too small, it is not preferable in terms of moire interference and light transmittance.
[0018]
The aperture ratio of the conductive pattern is 64 to 95%, preferably 75 to 95%, and more preferably 85 to 95%. When the aperture ratio is too large, it is not preferable in terms of shielding performance, and when it is too small, it is not preferable in terms of light transmittance.
[0019]
Metal layer
The thickness of the metal layer in this invention is 0.01-1 micrometer, Preferably, it is 0.05-0.5 micrometer, More preferably, it is 0.05-0.1 micrometer. When it is too thick, it is not preferable in carrying out patterning for thinning. Moreover, when too thin, it is unpreferable at the point of shielding performance.
[0020]
In the present invention, since the thickness of the metal layer is thinner than the conventional one, the pattern can be thinned, and there is an advantage of reducing and eliminating moire interference.
[0021]
The material of the metal layer is not particularly limited as long as it can be used as a conductive metal, and examples thereof include copper, gold, silver, aluminum, nickel, tin, chromium, and alloys thereof. . Among these, copper, gold, silver, aluminum, nickel or an alloy thereof is preferable, and copper or an alloy thereof is particularly preferable.
[0022]
About copper, it is preferable that it is pure copper as much as possible. The alloy is mainly composed of copper, such as Cu / Zn (brass), Cu / Sn (bronze), Cu / Al, Cu / Ni, Cu / Pd, phosphor bronze, Cu / Be, etc. These alloys can be preferably used.
[0023]
Further, the metal layer is not limited to a single metal layer but may be a laminated layer. For example, a two-layer, three-layer, or multilayered layer having a structure of chromium + copper or chromium + copper + chromium can be exemplified. At this time, for the metal layer disposed in the outermost layer, in order to maintain good visibility, a metal having a function of correcting the color from white to black color or a protective film function against the environment resistance of the intermediate layer is selected. It is preferable.
[0024]
Transparent substrate
The shape of the transparent substrate can be appropriately set according to the intended use. Usually, it is used as a flat sheet, but may be bent, or may be used as a film or plate depending on the application. The thickness of the transparent substrate is usually about 0.05 to 5 mm, preferably about 0.1 to 0.3 mm.
[0025]
As the material of the transparent substrate, inorganic materials such as glass, polymethyl methacrylate, polystyrene or a copolymer of styrene and acrylonitrile or methyl methacrylate, poly (4-methylpentene-1), polypropylene, cyclopentene, norbornene, tetracyclo Amorphous cyclic olefin polymer by cyclic olefin monomer such as dodecane or copolymerization of ethylene, polyethylene terephthalate, polyethylene naphthalate, polyarylate, polyethersulfone, polycarbonate, thermoplastics such as various liquid crystalline polymers, acrylic Type, urethane type, epoxy type, silicone type thermosetting transparent resin and the like. Two or more of these may be used in combination.
[0026]
What is selected for the transparent substrate can be appropriately set according to various applications, but the total light transmittance is 50% or more, preferably 70% or more, more preferably 90% or more. . It means that it is transparent and excellent in visibility, so that this value is large. Further, those excellent in heat resistance, weather resistance, non-shrinkage, mechanical strength, chemical resistance and the like are preferable.
[0027]
Electromagnetic wave shielding transparent sheet
The sheet resistance value of the electromagnetic wave shielding transparent sheet of the present invention is 0.08 to 50Ω / □, preferably 0.4 to 10Ω / □, and more preferably 0.6 to 6Ω / □.
[0028]
When the sheet resistance value is too large, it is not preferable in terms of shielding characteristics.
[0029]
Here, the sheet resistance value will be described with reference to FIG. The sheet resistance value (Rs) on the entire surface of the metal layer is obtained by the following equation. ρv is the volume resistivity, and t is the thickness of the metal layer.
[0030]
Formula 2: Rs = ρv / t
Next, in obtaining the sheet resistance value after pattern formation, a structural unit as shown in FIG. 2 having a resistance value r (Ω) is considered. For example, in the sheet resistance value R (Ω / □) having a pattern in which this structural unit is composed of 2 × 2, the longitudinal resistance is considered to be equipotential (for example, current does not flow between AB and BC). Therefore, it can be ignored, and is obtained from the combined resistance of the 2 × 2 equivalent circuit. That is, the relational expression R (Ω / □) = r (Ω) is established. This relational expression holds even if the structural unit is expanded to n × n. This r (Ω) is obtained from the relationship of Formula 3 from the pitch width b of the pattern, the line width a, and the sheet resistance value Rs of the entire metal layer.
[0031]
Formula 3: r = Rs × (b / a)
The sheet resistance value R after pattern formation is finally obtained from R (Ω / □) = Rs × (b / a). For reference, even when the pattern is inclined by 45 °, a relational expression of R = r can be obtained by an equivalent circuit from the following structural units. When the sheet resistance value is required as the characteristic value, the sheet resistance after the pattern formation can be arbitrarily designed based on the sheet resistance value of the base material before the pattern is formed and the designed line width and pitch width.
[0032]
Specifically, the volume specific resistance value (ρv) of the metal is chromium 12.9 × 10^-6Ωcm, nickel 6.84 × 10^-6Ωcm, tin 11.0 × 10^-6Ωcm, aluminum 2.65 × 10^-6Ωcm, gold 2.35 × 10^-6Ωcm, silver 1.59 × 10^-6Ωcm, copper 1.67 × 10^-6Ωcm.
[0033]
The electromagnetic wave shielding transparent sheet of the present invention may be used alone, or may be used as a composite sheet in which (i) a shield layer made of the sheet, (ii) an antireflection layer, and (iii) a near infrared cut layer are laminated. Good.
[0034]
The composite sheet can be used as a filter for an image display device such as a PDP.
[0035]
The antireflection layer is a layer for the purpose of suppressing the reflection of the surface and improving the transmittance of the filter, such as metal oxide, fluoride, silicide, boride, carbide, nitride, sulfide, etc. A method of laminating inorganic materials in a single layer or multiple layers by vacuum deposition, sputtering, ion plating, ion beam assist, etc., or laminating a resin having a different refractive index such as acrylic resin or fluororesin in a single layer or multiple layers It can be formed by a method or the like. Further, an antiglare layer (non-glare layer) may be laminated. The non-glare layer is a layer intended to widen the viewing angle of the filter. In order to scatter the transmitted light, the non-glare layer is formed by, for example, a method of coating powder on silica, melamine, acrylic, or the like and coating the surface. be able to. The ink can be cured by thermal curing or photocuring.
[0036]
The near-infrared cut layer is installed on the front surface of the display for the purpose of preventing malfunction in remote control or transmission optical communication due to near-infrared rays emitted from the plasma display. The near-infrared light cut region is 800 to 1000 nm for remote control and transmission optical communication as a particularly problematic wavelength, and a near-infrared absorbing material having absorption in that region is used. The near-infrared absorbing materials include nitroso compounds and their metal complexes, cyanine compounds, dithiol nickel complex compounds, aminothiol nickel complex compounds, phthalocyanine compounds, triallylmethane compounds, imonium compounds, and diimonium compounds. , Naphthoquinone compounds, anthraquinone compounds, amino compounds, aminium salt compounds of near infrared absorbing dyes, or near infrared absorbing compounds such as carbon black, indium tin oxide and antimony tin oxide may be used alone or in combination. it can.
[0037]
The near-infrared cut layer can be formed by adding a near-infrared absorbing substance to the pressure-sensitive adhesive layer. Examples of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer include rubbers such as styrene butadiene rubber, polyisobutylene, natural rubber, neoprene and butyl rubber, and polyacrylic acid alkyl esters such as polymethyl acrylate, polyethyl acrylate and polybutyl acrylate. Examples thereof include polymers having a low polymerization degree such as those obtained by adding a picolite, a polypel, a rosin ester or the like as a tackifier to these polymers.
[0038]
When attaching a filter to the plasma display, if bubbles enter between the surface of the plasma display and the filter, the image may be distorted or difficult to see. There is a need to. Moreover, since the surface of the plasma display itself becomes high temperature, an adhesive that generates gas by heating should be avoided.
[0039]
Specifically, polymer adhesive such as polyacrylic acid alkyl ester, or rubber adhesive such as styrene butadiene rubber, natural rubber, halogen, alcohol, ketone, ester, ether, aliphatic Dipping method, flow coating method, spray method, bar coating method, gravure coating method by adjusting viscosity by dispersing or dissolving organic solvents such as hydrocarbons, aromatic hydrocarbons, etc. in a solvent system that is single or mixed. Coating is performed by a coating method such as a roll coating method, a blade coating method, or an air knife coating method, and then the solvent is dried to form an adhesive layer.
[0040]
The thickness of the pressure-sensitive adhesive layer at this time is usually 5 to 100 μm, preferably 10 to 50 μm. A release film may be provided on the surface of the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer may be protected until it is attached to the surface of the plasma display so that dust or the like does not adhere to the pressure-sensitive adhesive layer.
[0041]
The composite sheet of the present invention can further be provided with a hard coat layer, a contamination prevention layer, or the like, if necessary.
[0042]
Further, the composite sheet of the present invention may be bonded to a support such as tempered glass and used in the form of a laminated sheet.
[0043]
Method for manufacturing electromagnetic shielding transparent sheet
The electromagnetic wave shield of the present invention is formed by sequentially performing the steps described in the following (A) to (D).
(A) forming a metal layer having a thickness of 0.01 to 1 μm on one side of the transparent substrate by a thin film forming means;
(B) developing the metal layer by a photolithography method to expose a non-conductive pattern portion;
(C) a step of chemically etching the non-conductive pattern portion to dissolve and remove the metal layer;
(D) A step of peeling and removing the remaining resist of the conductive pattern.
[0044]
First, step (a) will be described.
[0045]
In the step (a), a metal layer having a thickness of 0.01 to 1 μm is formed on one side of the transparent substrate by physical means.
[0046]
Here, the thin film forming means is a generally used thin film forming technique, and examples thereof include a chemical thin film forming means and a physical thin film forming means. Specific examples of the chemical thin film forming means include a plating method and a CVD method. Examples of the physical thin film forming means include sputtering, vacuum deposition, and ion plating.
[0047]
In common, these metals or non-metals are made into a gas or ion state by some method, received on the surface of the transparent substrate, and deposited to form a thin film. Use copper or its alloys.
[0048]
Among the thin film forming means, the sputtering method or the ion plating method is preferable from the viewpoint of adhesion with the substrate.
[0049]
More specifically, sputtering deposition is performed on one surface of a sheet-like transparent substrate by sputtering to form a thin film having a thickness of 0.01 to 1 μm using copper or an alloy thereof as a target.
[0050]
In this sputtering, it is not necessary to perform any pretreatment on the sheet, and it can be carried out immediately. However, depending on the case, the surface may be degreased and washed or subjected to a pretreatment such as a discharge treatment using glow or corona. Good. Sputtering conditions may be performed according to general conditions, but low gas pressure sputtering performed under a low gas pressure (the gas is an inert gas such as argon) is preferable. This low gas pressure sputtering corresponds to sputtering with a tripolar glow discharge, a bipolar glow RF discharge, a magnetron, or an ion beam. The sputtering with a magnetron has a high speed and a high purity of a thin film to be formed. It is more preferable because the temperature generated in the vacuum chamber is low.
[0051]
Next, step (b) will be described.
[0052]
The metal layer obtained in the step (a) is developed using a photolithography method to expose a desired pattern. Here, the photolithographic method refers to generally performed application of a photosensitive resist → vacuum adhesion of a masking film → exposure → development for dissolving and removing an exposed portion or an unexposed portion → exposure of a desired pattern. The photosensitive resist includes a negative type and a positive type. When the negative type is exposed and receives ultraviolet rays, only the portion is photocured. The positive type has a light characteristic opposite to that of the negative type, and a portion that receives ultraviolet light undergoes photolysis. If both development processes are performed, the unexposed portion is dissolved and removed in the negative type, and the exposed portion is dissolved and removed in the positive type. Therefore, a positive mask (pattern is black) is used for the positive type and a negative mask (pattern is transparent) is used for the negative type.
[0053]
The type of the photosensitive resist is not particularly limited. Generally, an acrylic type is used for the negative type, and a diazo type is used for the body type. In addition, since the resist is generally in a liquid state, it is applied by a coating method. However, the resist may be in the form of a film in advance like a dry film.
[0054]
Next, step (c) will be described. The chemical etching in (c) is an operation of chemically dissolving and removing the metal constituting the metal layer with an etching solution. Accordingly, the etching solution is not limited as long as the metal dissolves. Generally, it is a commonly used aqueous solution of ferric chloride or cupric chloride, but it is preferable to use, for example, a sulfuric acid / hydrogen peroxide aqueous solution that can be etched more gently than these.
[0055]
In the present invention, since the metal layer is thin, the chemical etching time can be as short as about 30 to 60 seconds.
[0056]
Finally, step (d) will be described. The photosensitive resist layer of the remaining conductive pattern portion is peeled and removed. The stripping removal is generally performed by spraying or rocking dipping using various organic solvents or stripping chemical solutions of an alkaline aqueous solution.
[0057]
Immediately after completion, wash with water and dry to finish the whole process.
[0058]
FIG. 3 shows the structure of the product obtained by processing in each of the above steps according to (a) to (2). In FIG. 3, a part of the structure is shown in a sectional view. In FIG. 3, 1 is a transparent substrate, 2 is a metal layer, and 3 is a photosensitive photoresist.
[0059]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
[0060]
Example 1
A biaxially stretched polyethylene terephthalate film (hereinafter referred to as a PET film) having a thickness of 125 μm, a size of 400 × 1000 mm, and Tt = 90% is placed in a vacuum chamber of a magnetron sputtering apparatus facing a copper target, and air is supplied. Degree of vacuum 2 × 10 obtained by completely replacing with argon^-3Under the Toll environment, sputter deposition was repeated three times at 1 m / min with an applied voltage of DC 9 kW.
[0061]
The thickness of the copper thin film obtained above was uniform at about 0.1 μm. Further, a part of the film was cut off and subjected to a tape peeling test.
[0062]
Next, a positive resist was coated with a roll coater on the sputtered surface of the obtained copper sputtered PET film, and the resist layer having a thickness of 5 μm was provided. Then, a positive mask depicting a pattern having a line width of 5 μm, a pitch width of 100 μm, a pitch width with respect to the line width of 20, and an aperture ratio of 90% was vacuum-adsorbed on the resist layer surface, and then exposed.
[0063]
As the positive mask, a masking film in which the pattern portion was black, the non-pattern portion was transparent, and the opening was drawn in a square shape was used. Exposure is 130 mJ / cm using an ultra-high pressure mercury lamp as a light source.²Was performed. The resist of the non-pattern part was decomposed | disassembled by this exposure, This part was melt | dissolved and removed with the developing solution, and it finally washed with water and dried. The resist in the pattern portion remained in close contact with the copper sputtering surface. Therefore, the pattern portion is masked, and the copper sputter layer is exposed in the non-pattern portion.
[0064]
The entire surface was etched under the following conditions. As a chemical etching solution, an aqueous solution containing sulfuric acid and hydrogen peroxide was used. The solution was put in a bath and etched while stirring. The etching time was 30 seconds, and after 30 seconds, it was immediately washed with water and dried.
[0065]
Next, brushing was performed with a light touch while spraying acetone over the entire surface to dissolve and remove the remaining resist in the pattern portion, followed by washing with water and drying to obtain a transparent sheet on which a conductive pattern was formed on a PET film.
[0066]
Comparative Example 1
A biaxially stretched polyethylene terephthalate film (hereinafter referred to as a PET film) having a thickness of 125 μm, a size of 400 × 1000 mm, and Tt = 90% is placed in a vacuum chamber of a magnetron sputtering apparatus facing a copper target, and air is supplied. Degree of vacuum 2 × 10 obtained by completely replacing with argon^-3Sputtering was repeated three times at 1 m / min with an applied voltage of DC 9 kW in a Toll environment.
[0067]
The thickness of the copper thin film obtained above was uniform at about 0.1 μm. Further, a part of the film was cut off and subjected to a tape peeling test.
[0068]
Next, a positive resist was coated with a roll coater on the sputtered surface of the obtained copper sputtered PET film, and the resist layer having a thickness of 5 μm was provided. Then, a negative mask on which a pattern having a line width of 15 μm, a pitch width of 322 μm, a pitch width with respect to the line width of 21.5, and an aperture ratio of 90% was vacuum-adsorbed on the resist layer surface, and then exposed.
[0069]
As the negative mask, a masking film in which a pattern portion was transparent, a non-pattern portion was black, and an opening portion was drawn in a square shape was used. Exposure is 130 mJ / cm using an ultra-high pressure mercury lamp as a light source.²Was performed. By this exposure, the resist of the pattern portion was decomposed, and this portion was dissolved and removed with a developer, and finally washed with water and dried. The resist in the non-patterned portion remained in close contact with the copper sputtering surface. Therefore, the non-pattern part is masked, and the copper sputter layer is exposed in the pattern part.
[0070]
Next, copper was electrolytically plated on the exposed pattern under the following conditions. That is, using phosphorous copper as an anode, the pattern as a cathode, a mixed solution of copper sulfate, sulfuric acid and water as a plating solution, a bath temperature of 23 ° C., and a cathode current density of 1.7 A / dm.²Electrolytic plating was performed at a plating rate of 0.3 μm / min. It was washed thoroughly with water and dried.
[0071]
Next, brushing was performed with a light touch while spraying acetone over the entire surface of the electroplated material, and the remaining resist in the non-patterned portion was dissolved and removed, washed with water, and dried. When the obtained part was cut out and the cross section was magnified and observed with a microscope, the laminated copper plating layer had a prism shape very sharply.
[0072]
Next, the whole surface was etched under the following conditions.
[0073]
As a chemical etching solution, an aqueous solution containing sulfuric acid and hydrogen peroxide was used. The solution was put in a bath and etched while stirring. The etching time was 30 seconds, and after 30 seconds, it was immediately washed with water and dried to obtain a transparent sheet on which a conductive pattern was formed on a PET film. The final metal (copper) layer thickness was 2.7 μm.
[0074]
Test example 1
The sheet obtained in Example 1 and the sheet obtained in Comparative Example 1 were examined for electromagnetic wave shielding characteristics, sheet resistance value, and total light transmittance. The electromagnetic wave shielding characteristic is expressed by an electromagnetic wave attenuation rate (dB-decibel) measured in a frequency range of 0 to 1000 MHz (megahertz) by a measuring device in the Kansai Electronics Industry Promotion Center method (generally called KEC method). did. The sheet resistance value was measured with a sheet resistance measuring machine (Loresta-EP (MCP-T360) manufactured by Mitsubishi Chemical Corporation, probe used: ESP). The total light transmittance was measured by a turbidimeter type NDH-20D manufactured by Nippon Denshoku Industries Co., Ltd., which was produced based on JIS K7105 (1981).
[0075]
Regarding the test results of the electromagnetic wave shielding characteristics, the result of Example 1 is shown in FIG. 4, and the result of Comparative Example 1 is shown in FIG. Table 1 shows the results of examining the characteristics of each sheet including the sheet resistance value and the total light transmittance.
[0076]
[Table 1]

[0077]
As is clear from the results shown in FIGS. 4 and 5 and Table 1, it was found that the sheet of the present invention has a good shielding property even though the sheet resistance value is high. In particular, it has been clarified that electromagnetic waves in a frequency band (30 to 300 MHz), which is regarded as a problem by radiation noise of PDP, are significantly shielded.
[0078]
Example 2
When the electromagnetic wave shielding transparent sheet prepared in Example 1 was installed on the front surface of the PDP, moire did not occur. Further, even when the facing angle with the PDP was shifted by 45 degrees, no moire was generated. From this, it became clear that the moire phenomenon is reduced or eliminated by the present invention.
[0079]
【The invention's effect】
By having the above-described configuration, the present invention can perform fine wire processing, and also has an excellent effect of having good transparency and shielding characteristics. In particular, in the present invention, there is an advantageous effect that cannot be predicted from the prior art that electromagnetic waves in the low frequency region are significantly shielded.
[0080]
In addition, the present invention has the effect that the moire phenomenon is reduced or eliminated by enabling fine fine wire processing. This eliminates the need for adjusting the angle for eliminating moire as in the prior art, and also eliminates the need for adjusting the bias angle for each model such as a PDP.
[0081]
Furthermore, when manufacturing the sheet of the present invention, there is an advantage that an electromagnetic shielding transparent sheet can be obtained easily and easily without requiring a complicated process such as plating. In addition, since the thickness is reduced, there is an advantage that the problem of bubble entrapment at the time of bonding with the adhesive film is reduced.
[0082]
Since the transparent sheet of the present invention has such excellent physical properties, it is useful for shielding electromagnetic waves from electromagnetic wave generating devices such as PDPs.
[Brief description of the drawings]
FIG. 1 is a plan view showing a configuration when a pattern is a square lattice pattern.
FIG. 2 is a diagram showing a model circuit for calculating a sheet resistance value.
FIG. 3 is a cross-sectional view showing the structure of the sheet of the present invention obtained by processing in the steps (a) to (d).
FIG. 4 is a view showing electromagnetic wave shielding characteristics of an embodiment of the present invention.
FIG. 5 is a drawing showing electromagnetic shielding characteristics of a comparative example.

Claims (5)

An electromagnetic wave shielding transparent sheet having a conductive pattern made of a metal layer on a transparent substrate, the thickness of the metal layer being 0.01 to 0.1 μm,
The line width (a) of the conductive pattern is 1 to 10 μm,
The pitch width (b) of the conductive pattern is 10 to 100 μm,
The ratio (b / a) of the pitch width to the line width of the conductive pattern is 15 to 25 ,
A transparent sheet obtained by sequentially performing the steps described in the following (a) to (d).
(A) forming a metal layer on one side of the transparent substrate by a thin film forming means;
(B) developing the metal layer by a photolithography method to expose a non-conductive pattern portion;
(C) a step of chemically etching the non-conductive pattern portion to dissolve and remove the metal layer;
(D) A step of peeling and removing the remaining resist of the conductive pattern. The electromagnetic wave shielding transparent sheet according to claim 1, wherein the opening ratio of the conductive pattern is 64 to 95%. The electromagnetic wave shielding transparent sheet according to claim 1, wherein the sheet resistance value is 0.08 to 50Ω / □. The method for producing an electromagnetic wave shielding transparent sheet according to any one of claims 1 to 3, wherein the steps described in the following (a) to (d) are sequentially performed.
(A) a step of forming a metal layer having a thickness of 0.01 to 0.1 μm on one side of the transparent substrate by a thin film forming means
(B) developing the metal layer by a photolithography method to expose a non-conductive pattern portion;
(C) a step of chemically etching the non-conductive pattern portion to dissolve and remove the metal layer;
(D) A step of peeling and removing the remaining resist of the conductive pattern. (I) a shield layer comprising the electromagnetic wave shielding transparent sheet according to any one of claims 1 to 3;
A composite sheet having (ii) an antireflection layer, and (iii) a near infrared cut layer.

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