JP2000196286A - Translucent electromagnetic wave shielding member and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a translucent electromagnetic wave shielding member being excellent in an electromagnetic wave shielding effect, translucency, visibility and an angle of a field and manufactured at low cost, and a manufacturing method thereof. SOLUTION: A translucent electromagnetic wave shielding member 1 has an electromagnetic wave shielding pattern 10 constituted of a pattern 10a formed on the surface of a translucent base 2 by printing by an intaglio offset printing method using a blanket excellent in ink releasability, with conductive paste containing metal powder and resin used, and of a metal film 10b formed on the surface of the pattern 10a by electroplating. It is characteristic in that the ratio Sk/Ss between the whole area Ss of a region wherein the shielding pattern 10 is formed and the whole area Sk of a region wherein the shielding pattern is not formed meets the condition of being 1-9 and in that a line width Ws is 5-40 μm and a film thickness 0.5-50 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a translucent electromagnetic wave shielding member capable of effectively shielding electromagnetic waves emitted from a display section of an electronic device such as a CRT (CRT), a PDP (Plasma Display Panel), and the like. And its manufacturing method.

[0002]

2. Description of the Related Art In recent years, various reports have been made on the effects of electromagnetic waves radiated from electric devices on the human body.
Along with this, there is increasing interest in techniques for shielding electromagnetic waves radiated from a display screen such as a CRT. Conventionally,
In order to shield electromagnetic waves radiated from a display screen, an electromagnetic wave shielding member having a pattern made of a metal such as a copper foil formed on a surface of a transparent base material such as a transparent film is used. This electromagnetic wave shield member has a shield (shield) for electromagnetic waves.
In addition to being highly effective, it is required to have excellent translucency (transparency) and visibility, and to have a wide viewing angle. In particular, an electromagnetic wave shielding member for a PDP which is attracting attention as a next-generation image display device. Since electromagnetic waves emitted from a display screen of a PDP are stronger than a CRT or the like, more excellent electromagnetic wave shielding characteristics are required.

As a standard for the electromagnetic wave shielding effect, the Swedish MPRII standard is known as the strictest standard in the world, and is becoming a practical standard. In order to satisfy this standard, it is necessary to sufficiently cut electromagnetic waves in an extremely wide frequency range of 1 to 1000 MHz.

[0004]

The electromagnetic wave shielding effect,
Japanese Patent Application Laid-Open No. H10-163 discloses a method for manufacturing an electromagnetic wave shielding member that sufficiently satisfies various characteristics such as translucency, visibility, and viewing angle.
No. 673 and JP-A-5-16281 disclose that a copper foil layer is formed on the surface of a transparent substrate by electroless plating, a resist pattern is formed by a photolithographic method, and then the copper foil layer is patterned by etching. A method for doing so is disclosed. If a pattern is formed by the etching process in this manner, a very fine pattern can be formed with high accuracy. However, since most of the thin copper layer formed by plating is removed by etching, there is a problem that the manufacturing cost of the electromagnetic wave shielding member increases, such as waste of copper material and cost of waste liquid treatment. is there.

In particular, since PDPs are mainly developed for large screens, the size of the electromagnetic wave shielding member is also required to be increased. In this case, an exposure apparatus for forming a resist pattern in a photolithography method, an etching apparatus for etching, and the like. It is necessary to increase the size of the device and the like, and costs are increased in terms of capital investment. On the other hand, Japanese Patent Publication No. 2-48159 discloses an electromagnetic wave shielding member in which an electromagnetic wave shielding pattern made of a conductive paste containing a metal powder and a resin is formed on a transparent substrate by pattern printing. According to such an electromagnetic wave shielding member, since the formation of a copper coating layer by the above-described electroless copper plating or the like and the etching treatment are not required, the production thereof is simple, and there is no need to worry about copper waste liquid treatment. In addition, the amount of metal used, such as copper, is sufficient for the pattern formation, so that manufacturing costs can be reduced.

However, when an electromagnetic wave shielding pattern is formed by a printing method, a sufficient electromagnetic wave shielding effect and light transmission cannot generally be achieved at the same time, and at present, it has not been put to practical use. For example, in order to enhance the electromagnetic wave shielding effect, it is necessary to increase the thickness of the pattern and increase the amount of the metal powder in the pattern.

Further, in order to obtain good translucency, it is necessary to make the line width of the pattern extremely small and increase the interval between them, but it is difficult to form a fine pattern by the above-mentioned printing method. That is, in the screen printing method, since the screen plate is stretched at the time of printing, the mesh expands and contracts, causing a variation of about ± 20 μm in the printing dimensions and the printing position. Further, when a pattern having a line width of 50 μm or less is printed by a conventional screen printing method or a gravure printing method, variations in the pattern line width and disconnection occur, and the electromagnetic wave shielding effect and visibility are reduced.

Further, in the conventional method of forming a pattern with a conductive paste containing a metal powder and a resin, the heating temperature for curing the pattern is limited due to the heat resistance of the transparent substrate. As a result, there is a problem that the conductive paste cannot be sufficiently cured and the conductive shield effect is reduced. Therefore, an object of the present invention is to solve the above-mentioned problems, to have an excellent electromagnetic wave shielding effect, to be excellent in each property of translucency, visibility and a viewing angle, and to have a low manufacturing cost. It is to provide.

Another object of the present invention is to provide a light-transmitting electromagnetic wave shielding member which has an excellent electromagnetic wave shielding effect and also has excellent characteristics of light transmission, visibility and viewing angle at low cost. An object of the present invention is to provide a manufacturing method that can be easily manufactured.

[0010]

According to an aspect of the present invention, there is provided a light-transmitting electromagnetic wave shielding member in which a conductive paste containing a metal powder and a resin is printed on a surface of a transparent substrate. A translucent electromagnetic wave shielding member having an electromagnetic wave shielding pattern comprising a formed pattern and a metal film formed by electroplating on the surface of the pattern, wherein the shield pattern is formed on the surface of the transparent base material. The total area Ss of the region where the shield pattern is not formed and the total area Sk of the region where the shield pattern is not formed are expressed by the formula (1)
: 1 ≦ Sk / Ss ≦ 9, and the line width Ws of the shield pattern is 5 to 5.
The thickness is 40 μm, and the film thickness Wt is 0.5 to 50 μm.

[0011] The method for producing a light-transmitting electromagnetic wave shielding member according to the present invention is characterized in that an intaglio offset printing using a blanket excellent in ink releasability is performed by using a conductive paste containing a metal powder and a resin. After printing on the surface of the pattern to form a pattern, this pattern is cured, then a metal coating is provided only on the surface of the pattern by electroplating, and the area of the transparent substrate surface where the electromagnetic wave shielding pattern is formed The total area Ss and the total area Sk of the region where the shield pattern is not formed are expressed by the following equation.
(1): An electromagnetic wave shield pattern satisfying 1 ≦ Sk / Ss ≦ 9, having a line width Ws of 5 to 40 μm and a film thickness Wt of 0.5 to 50 μm is formed.

According to the above-mentioned light-transmitting electromagnetic wave shielding member of the present invention, a pattern made of a conductive paste is printed on a transparent substrate by, for example, intaglio offset printing using a blanket having excellent ink release properties. A metal coating is selectively provided only on the surface of the pattern by electroplating. Therefore, the shielding member having the electromagnetic wave shielding pattern obtained in this way is compared with a conventional shielding member in which a metal film is formed on a transparent substrate by electroless plating or the like, and this is patterned by photolithography, etching, or the like. Therefore, the manufacturing process is simple and the manufacturing cost is greatly reduced.

The line width W of the conductive shield pattern
Since s, the film thickness Wt, and the ratio Sk / Ss are each set within the above-mentioned predetermined ranges, the electromagnetic wave shielding effect, light transmission, visibility, and viewing angle are all excellent. Furthermore, since the metal film by electroplating is provided on the surface of the pattern made of the conductive paste, even when the heat curing of the conductive paste cannot be sufficiently performed due to the low heat resistance of the transparent base material. An excellent electromagnetic wave shielding effect can be obtained.

According to the electroplating, although metal is deposited on a pattern made of a conductive paste containing metal powder, polyethylene terephthalate (PET) is used.
No metal is deposited on the surface of plastic or glass, such as the surface of a transparent substrate. Therefore, according to the present invention, only the surface of the pattern made of the conductive paste on the transparent substrate is selectively plated.

On the other hand, according to the method for manufacturing a light-transmitting electromagnetic wave shielding member of the present invention, any of the characteristics of the electromagnetic wave shielding effect, light-transmitting property, visibility, and viewing angle can be achieved with a simple process and at low cost. Thus, an excellent light-transmitting electromagnetic wave shielding member can be manufactured. In the manufacturing method of the present invention, the electroless plating is performed on the pattern made of the conductive paste.
No plating is applied to the entire surface of the transparent base material or most of the plating layer is removed by etching, unlike the invention disclosed in Japanese Patent Application Laid-Open No. Hei. Therefore, as compared with the invention disclosed in the above-mentioned publication, the cost for plating and etching and the cost for plating metal and waste liquid treatment can be significantly reduced.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. As shown in FIG. 1, for example, a translucent electromagnetic wave shielding member 1 according to the present invention has an electromagnetic wave shielding pattern 10 formed on a surface of a transparent base material 2, and the shielding pattern 10 is made of a metal powder and a resin. And a metal film 10b formed by electroplating on the surface of the pattern by printing a conductive paste containing

[Shape of Electromagnetic Wave Shield Pattern] Examples of the shape of the electromagnetic wave shield pattern include a stripe pattern 11 shown in FIG. 2 and lattice patterns 12 and 13 shown in FIGS. The shape of the electromagnetic wave shield pattern may be a geometric pattern other than the above-mentioned stripe shape and lattice shape. That is, for example, a triangle such as an equilateral triangle, an isosceles triangle, or a right triangle; a square;
Rectangle such as rectangle, rhombus, parallelogram, trapezoid; (positive)
Hexagon, (regular) octagon, (regular) dodecagon, (regular) N-gon such as (decagonal) octagon; geometric pattern obtained by repeating various graphic units such as circle, ellipse, star May be used as the electromagnetic wave shield pattern 10. In such a geometric pattern,
The graphic unit may be a combination of two or more types. In addition, from the viewpoint of smoothly removing static electricity from the electromagnetic wave shielding member, it is preferable that each figure unit in the geometric pattern is continuous. As a specific example of the pattern shape composed of a geometric pattern, for example, as shown in FIG. 5, a circular pattern (FIG. 5A), a diamond pattern (FIG. 5B), and a regular hexagonal pattern (FIG. 5C) And the like.

In FIGS. 2 to 4 and FIGS. 5A to 5C, the hatched portions indicate the electromagnetic wave shield patterns 10, and the unhatched portions indicate the regions where the electromagnetic wave shield patterns are not formed. 20 is shown.
Line width Ws and line spacing Wk of the electromagnetic wave shield pattern 10
(Interval between adjacent patterns 10) and film thickness Wt;
The ratio Sk / Ss of the total area Ss of the electromagnetic wave shield pattern 10 to the total area Sk of the region 20 where the shield pattern is not formed is within a range in which the electromagnetic wave shielding effect can be sufficient. In order to ensure the translucency of the electromagnetic wave shielding member, the shielding pattern 10
It is set within a range that cannot be recognized by the naked eye.

In the case where the electromagnetic wave shield pattern has a rectangular lattice shape (FIG. 3), there are two types of line intervals Wk of the shield pattern, Wk and Wk '. It is sufficient that Wk 'is within a predetermined range described later. In the case where the electromagnetic wave shield pattern is a geometric pattern, the line width Ws refers to the width of one unit (that is, a constituent unit such as a triangle, a quadrangle, an N-gon, a circle, an ellipse, etc.) constituting the geometric pattern. The line interval Wk refers to the distance between units, and the square root of the area of one unit (that is, the length of one side when one unit is simulated as a square) is calculated from the distance at the center position between adjacent units. The value obtained by subtracting the square root is defined as the distance between the units.

In the light-transmitting electromagnetic wave shielding member of the present invention, the total area Ss of the area where the electromagnetic wave shielding pattern is formed on the surface of the transparent base material and the total area Sk of the area where the shield pattern is not formed are calculated. Ratio Ss / S
k is 1 or more and 9 or less, and the line width Ws of the shield pattern is 5 to 40 μm and the film thickness Wt is 0.5 to 5
It is set to be 0 μm.

When the ratio Sk / Ss is less than 1, the light transmittance becomes insufficient. Conversely, if the ratio Sk / Ss exceeds 9, the electromagnetic wave shielding effect becomes insufficient. The ratio Sk / Ss is particularly preferably from 1 to 5 and more preferably from 1 to 3 in the above range. Line width W of electromagnetic wave shield pattern
It is difficult to form s less than 5 μm,
Disconnection is likely to occur, leading to a reduction in the electromagnetic wave shielding effect and the generation of defective products. Conversely, when the line width Ws is 40 μ
If it exceeds m, the electromagnetic wave shield pattern is easily recognized visually, leading to a decrease in light transmission. The line width Ws is particularly preferably 5 to 25 μm in the above range.
More preferably, it is 20 μm.

When the film thickness Wt of the electromagnetic wave shield pattern is 0.
If the thickness is less than 5 μm, disconnection of the pattern is likely to occur, and the conductivity is also reduced, which leads to a decrease in the electromagnetic wave shielding effect. Conversely, when the film thickness Wt exceeds 50 μm, the electromagnetic wave shield pattern is easily recognized depending on the angle at which the shield member is viewed, which leads to a decrease in visibility and a viewing angle, and eventually a decrease in light transmission. The film thickness Wt is particularly preferably 1 to 30 μm in the above range.

Aperture ratio (%) of translucent electromagnetic wave shielding member
Is determined from the line width Ws and the line interval Wk of the electromagnetic wave shield pattern by the following equation. Opening ratio = [Wk / (Wk + Ws)] ² × 100 Further, the opening ratio (%) has a relationship shown in the following equation with the ratio Sk / Ss. Sk / Ss = Aperture ratio / (100−Aperture ratio) In the translucent electromagnetic wave shielding member of the present invention, the aperture ratio is not particularly limited, and is determined according to the above-described ratio Sk / Ss and the like. Due to the balance between the translucency and the electromagnetic wave shielding property, it is usually 50 to 90%, preferably 60 to 90%.
It is set to be in the range of 80%. When the aperture ratio is less than the above range, the electromagnetic wave shielding effect is improved, but the light transmittance may be insufficient. Conversely, if it exceeds the above range, the electromagnetic wave shielding effect may be insufficient. In the case of a shield member for a PDP, since an excellent electromagnetic wave shielding property is required, the aperture ratio is particularly preferably 60% or more in the above range.

[Transparent Substrate] As the transparent substrate in the translucent electromagnetic wave shielding member of the present invention, in addition to having excellent translucency with respect to visible light, a conductive resin composition may be used. Since a heating process is performed after printing on a material, a material having sufficient heat resistance is preferable. Further, it is preferable that the material has flexibility so that continuous processing can be performed by winding the film into a roll at the time of manufacturing.

Specifically, transparent substrates include polyesters such as polyethylene terephthalate (PET); polyolefins such as polyethylene, polypropylene and polystyrene; vinyls such as polyvinyl chloride (PVC) and polyvinylidene chloride (PVDC). Polyether sulfone; acrylic resins such as polymethyl methacrylate (PMMA resin); polyamides and polyimide resins. Above all, a PET film having very good visible light transmittance and being inexpensive is preferably used.

The thickness of the transparent substrate is not particularly limited, but is preferably as thin as possible from the viewpoint of maintaining the translucency of the electromagnetic wave shielding member, and the form (film or sheet) in use and the required mechanical strength Usually 0.05, depending on
What is necessary is just to set suitably within the range of 5 mm. (Metal powder) In the present invention, examples of the metal powder to be blended in the conductive paste include powders of silver, copper, nickel, palladium, gold, aluminum, tungsten, chromium, titanium, and the like. A mixture of two or more types is used. In addition, in the present invention, in addition to the powder of the simple metal, a powder obtained by coating the surface of a copper powder or a nickel powder with silver can be used.

Among the metal powders exemplified above, silver powder is particularly preferably used because it is difficult to form an oxide having high insulation and has low volume resistivity. Although the nickel powder has a volume resistivity not smaller than that of the silver powder or the copper powder, it has a high oxidation resistance, and thus is suitable for producing an electromagnetic wave shield pattern portion in which the shielding effect has little change with time. Copper powder is apt to be oxidized on the surface, and therefore is preferably used together with a resin that generates a reducing gas when cured.

The packing density of the metal powder in the conductive resin composition is preferably higher from the viewpoint of enhancing the conductivity of the electromagnetic wave shielding pattern and further enhancing the electromagnetic wave shielding effect. However, if the packing density is too high, the conductivity tends to worsen. In general, the conductivity is
It is best when the filling ratio of the metal powder is around 80%.

The conductivity of the electromagnetic wave shield pattern is not determined only by the volume resistivity of the metal powder used itself, but is greatly influenced by the contact resistance between the metal powders inside the pattern. For example, even if metal particles are densely filled in the electromagnetic shield pattern, if the contact resistance between the metal powders is large, the conductivity of the entire pattern may be reduced.

Although the average particle size of the metal powder is not particularly limited, it is usually preferably set in the range of 1 to 15 μm in consideration of being uniformly mixed in the conductive resin composition. If the average particle size exceeds the above range, the number of contact points between the metal powders decreases, and the contact resistance may increase.
In addition, there is a possibility that the surface of the electromagnetic wave shield pattern becomes uneven. Conversely, if the average particle size is below the above range, it may be difficult to uniformly disperse the metal powder in the conductive resin composition. On the other hand, for the purpose of increasing the packing density of the metal powder, a metal powder having an average particle diameter in the above range and a small particle having an average particle diameter of 0.01 to 3 μm have a particle diameter of 100: 1 to 100: 50. You may mix by weight ratio.

The shape of the metal powder may be any shape such as a sphere or a scale. However, in consideration of increasing the contact surface between the metal powders (reducing the contact resistance), the scale is larger than the sphere. It is preferred to use ones in the form. The compounding amount of the metal powder is set according to the packing density of the metal powder and the conductivity required for the electromagnetic wave shielding pattern, and is not particularly limited, but is usually a resin component in the conductive paste. 400 to 100 parts by weight
It is set in the range of 1200 parts by weight, preferably 600 to 1000 parts by weight. If the compounding amount of the metal powder is less than 400 parts by weight, the contact points between the metal powders become insufficient, and the volume resistivity of the electromagnetic wave shielding pattern may increase. Conversely, if the amount of the metal powder exceeds 1200 parts by weight, the content of the resin with respect to the total amount of the conductive resin composition becomes too small, and the force for bonding the metal powder becomes small. May have an increased volume resistivity. The amount of the metal powder is 1
If the amount exceeds 200 parts by weight, the strength of the electromagnetic wave shield pattern may be insufficient.

[Conductive paste] In the present invention, the resin component used for the conductive paste includes, for example, polyester resin, polyvinyl butyral resin, ethyl cellulose resin, (meth) acrylic resin, polyethylene resin, polystyrene resin, polyamide resin and the like. Thermoplastic resin; polyester-melamine resin, melamine resin, epoxy-melamine resin, phenol resin, epoxy resin,
Any of thermosetting resins such as amino resin, polyimide resin, and (meth) acrylic resin can be used.

Among them, a resin that generates a reducing gas upon heating and curing is preferable because it can prevent oxidation of the metal powder and prevent a reduction in the volume resistivity of the metal powder. is there. Examples of such a resin include a thermosetting resin that generates a reducing gas such as ammonia, hydrogen halide, or formaldehyde during curing, preferably formaldehyde. Examples of the thermosetting resin that generates formaldehyde include a phenol resin (especially a resole-type phenol resin having many methylol groups) and an amino resin (especially a melamine resin).

The conductive paste is prepared by further adding a solvent to the mixture of the resin and the metal powder in order to obtain a viscosity suitable for printing by an intaglio offset printing method or the like. As the solvent to be used, for example, a solvent having a boiling point of 150 ° C. or more is preferably used. When the boiling point of the solvent is lower than the above range, the solvent tends to dry during printing, and pinholes may be generated.

Specific examples of usable solvents include hexanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, stearyl alcohol,
Alcohols such as seryl alcohol, cyclohexanol, and terpineol; ethylene glycol monobutyl ether (butyl cellosolve), ethylene glycol monophenyl ether, diethylene glycol, diethylene glycol monobutyl ether (butyl carbitol),
Cellosolve acetate, butyl cellosolve acetate,
Examples thereof include alkyl ethers such as carbitol acetate and butyl carbitol acetate, which may be appropriately selected in consideration of printability and workability.

When a higher alcohol is used as the solvent, there is a possibility that the drying property and fluidity of the ink may be reduced. Therefore, butyl carbitol, which has a better drying property than these, may be used.
Butyl cellosolve, ethyl carbitol, butyl cellosolve acetate, butyl carbitol acetate and the like may be used in combination. The amount of the solvent to be used is determined by the viscosity of the conductive paste, but usually is 10 to 100 parts by weight of the resin component in consideration of the amount of the metal powder.
The amount is preferably 0 to 500 parts by weight, preferably 100 to 300 parts by weight. When the amount of the solvent used falls below the above range, the viscosity becomes 1000 P (poise) or more even when the addition amount of the metal powder is the minimum of 400 parts by weight, and pinholes frequently occur when printing on a transparent substrate. I will. Conversely, if it exceeds the above range, the viscosity becomes 10 P or less even when the maximum amount of the metal powder used is 1000 parts by weight, and the adhesive strength to the transparent substrate is insufficient. As a result, the conductive paste is repelled from the transparent base material, and it becomes impossible to form an electromagnetic wave shielding pattern with a good printed shape.

In the present invention, the viscosity of the conductive paste is
Usually, it is preferably adjusted to 10 to 1000 P, preferably 100 to 500 P. If the viscosity is lower than the above range, the printed shape is deteriorated. On the other hand, when the viscosity is higher than the above range, many pinholes occur. It is preferable that the conductive paste of the present invention further contains a black pigment in addition to the resin component and the metal powder. The black pigment blackens the layer formed by printing the conductive paste, prevents reflection from external light, and contributes to improving the contrast of the display screen.

Examples of the black pigment include various conventionally known carbon blacks such as acetylene black. Also, the content of the black pigment in the conductive paste,
It is set in the range of 0.5 to 50% by weight based on the total amount of the conductive paste. If the amount of the black pigment is less than the above range, the effect of blackening becomes insufficient, and it may not be possible to improve the contrast. Conversely, if the amount of the black pigment exceeds the above range, the conductivity of the electromagnetic wave shielding pattern may be poor, and the electromagnetic wave shielding effect may be reduced.

In addition, if agglomeration or poor dispersion of the metal powder occurs in the conductive paste, a short circuit may occur between the internal electrodes. Therefore, a dispersant may be added to the conductive paste. Examples of the dispersant include various surfactants that are commonly used for preparing a conductive paste. Among them, a polymer surfactant is preferable from the viewpoint of stabilizing the conductive paste.

The conductive paste used in the present invention may optionally contain auxiliary agents such as a plasticizer, an antistatic agent, an antifoaming agent, an antioxidant, a lubricant, and a curing agent in addition to the above components. And
It is prepared by kneading and dispersing using a mixer such as a three roll or kneader. Further, in order to further improve the dispersibility of the metal powder, the metal powder may be sufficiently mixed in advance with a planetary mixer or the like before kneading with three rolls or the like.

[Printing of Conductive Paste] In the present invention, the conductive paste is prepared, for example, by intaglio offset printing using a blanket having excellent ink release properties.
Printed on a transparent substrate. The printed conductive paste is then cured by heating and drying to form a layer corresponding to the electromagnetic wave shielding pattern.

The printing method for printing the conductive paste is as follows.
The method is not particularly limited as long as it can be formed at t, but it is most preferable to use an intaglio offset printing method which has good linearity of formed lines and can reproduce and print an extremely fine pattern with high accuracy. According to the intaglio offset printing method, even when the line width of the pattern is extremely narrow,
A pattern having a uniform thickness can be formed.

Further, by using a blanket having excellent ink release properties, it is possible to transfer 100% of the ink transferred from the intaglio to the blanket onto the transparent substrate, and a sufficient film can be formed by one printing. A pattern having a thickness can be formed. For example, when an intaglio having a depth of 10 μm and a blanket whose surface rubber is made of silicone rubber is used, a pattern having a thickness of about 5 μm can be formed by one printing. Therefore, it is not necessary to repeat printing to obtain a film thickness necessary for the conductive shield pattern, and it is possible to reduce the manufacturing cost. In addition,
Assuming that the cost when the conductive paste is formed by printing the conductive paste by the intaglio offset printing method is 1, the cost when the conductive shield pattern is formed by the photolithographic method is 3 to 10.

Examples of the intaglio used in the present invention include glasses such as soda lime glass, non-alkali glass, quartz glass, low alkali glass, and low expansion glass; fluororesins, polycarbonate resins, polyethersulfone resins, polymethacrylic resins, etc. Resin; stainless steel, copper,
A metal such as low expansion alloy invar is used. Among them, the use of soft glass such as soda lime glass,
This is preferable for reproducing a fine pattern with high accuracy.

The surface of the intaglio printing plate is required to be extremely flat in order to prevent non-image areas from being left unscraped by doctoring and causing stains on the non-image area (ground stains). In order to produce an intaglio with excellent surface flatness at the lowest cost, it is preferable to produce an intaglio by etching using the glass exemplified above. The line width, line interval, and depth of the intaglio recess are appropriately set according to the shape of the electromagnetic wave shield pattern portion.

The blanket used in the present invention is not particularly limited as long as it has excellent ink releasability. For example, the surface is made of silicone rubber, fluororesin, fluororubber or a mixture thereof. Blanket. The silicone rubber is roughly classified into a room temperature-curable silicone rubber (RTV) and a heat-curable silicone rubber (HTV). In the present invention, any of the above types can be used. But,
RTV silicone rubbers that do not generate any by-products at the time of curing are more preferably used because they have better dimensional accuracy.

An index indicating the ink releasability of the blanket includes, for example, the surface energy of the blanket surface, and the value is preferably from 15 to 30 dyn / cm, more preferably from 18 to 25 dyn / cm. . The hardness of the blanket has a great effect on the transferability of the ink from the intaglio to the blanket. For high-precision printing, the JIS A hardness is in the range of 20 to 70, preferably 30 to 60. Is preferred. Also,
Since the surface roughness of the blanket greatly affects the shape of the pattern to be formed, it is preferable to use a blanket having a flat surface.

The pattern of the conductive resin composition printed and formed on the transparent substrate is usually cured by heating at 80 to 250 ° C. for 10 to 90 minutes, preferably at 100 to 150 ° C. for 15 to 60 minutes. . [Formation of Metal Coating] In the present invention, a metal coating is formed by electroplating on the surface of a pattern formed by printing and curing a conductive paste on a transparent substrate.

Examples of the metal film formed by electroplating include a film made of a metal such as copper, nickel, and gold. Also, taking into account that the surface of the metal film is oxidized, for example, after copper plating, the surface is further plated with nickel or gold to form a plating film composed of two or more metals. You may. Electroplating is performed by the following method. That is, the conductive paste is printed and cured on a transparent substrate to form a layer made of the paste, and then the transparent substrate is immersed in a plating solution for electroplating. Next, an electric current is applied to the plating solution using the transparent substrate as a cathode and the target metal alone for plating as an anode.

The composition of the plating solution used for electroplating is not particularly limited, and it can be prepared according to a conventional method. For example, when forming copper plating, an aqueous solution of copper sulfate may be used as a plating solution. In the above electroplating, on the surface of the pattern made of the conductive paste, since the pattern contains metal powder and has conductivity, a metal is deposited and a target metal film is formed. On the other hand, no metal is deposited on the surface of the transparent substrate made of plastic or glass, and no metal film is formed. Therefore, by electroplating the transparent substrate on which the layer made of the paste is formed, only the surface of the pattern is selectively plated.

The metal powder is not completely exposed on the surface of the pattern made of the conductive paste. For this reason, it is preferable to perform processing (activation) in which the resin on the pattern surface is etched to expose the metal powder on the surface. Such an activation treatment usually involves forming a pattern made of a conductive paste in concentrated sulfuric acid (98%) and concentrated hydrochloric acid (36%) at 30 to 50 ° C. for 3 to 3 hours.
It may be carried out by immersion for about 5 minutes.

[Embodiment of translucent electromagnetic wave shielding member]
The translucent electromagnetic wave shielding member of the present invention is, for example, a CRT,
By being installed on the front of the display screen of a display such as a PDP, it is used for the purpose of shielding electromagnetic waves radiated from the display screen, and a transparent adhesive layer is formed on the surface of a light-transmitting electromagnetic wave shielding member. By attaching a display panel or a transparent substrate of the display to the display panel, it can be used as an electromagnetic wave shielding panel integrated with the display.

[0053]

The present invention will be described below with reference to examples and comparative examples. [Manufacture of translucent electromagnetic wave shielding member] As the conductive paste, polyester resin [manufactured by Sumitomo Rubber Industries, Ltd .;
80 parts by weight of an ester of trimellitic anhydride and neopentyl glycol, weight average molecular weight Mw = 20,000, and a melamine resin [Sumimar M- manufactured by Sumitomo Chemical Co., Ltd.]
100C ”], 20 parts by weight, acetylene black 5 parts by weight, and flake-form silver powder [Fukuda Metal Foil Powder Co., Ltd., average particle size 5 μm] 800 parts by weight were mixed, and butyl carbitol acetate and carbon number 13 were mixed. Adjust the viscosity with a mixture (30-50 parts by weight) with a higher alcohol of ~ 15,
Further, p-toluenesulfonic acid (1-2) as a curing catalyst
Parts by weight) (hereinafter referred to as “silver paste”), or 800 parts by weight of flake-form copper powder (manufactured by Fukuda Metal Foil & Powder Co., Ltd., average particle size 5 μm) instead of silver powder Other than the above, any one prepared in the same manner as the above “silver paste” (hereinafter referred to as “copper paste”) was used.

As a transparent substrate, a polyethylene terephthalate (PET) film having a thickness of 100 μm was used.
When printing the conductive paste by intaglio offset printing, the intaglio should be made of soda lime glass.
The surface of the blanket is made of silicone rubber [additional silicone rubber of room temperature curing type, rubber hardness (JIS-A hardness 4)
0)] (10-point average roughness of the surface of 0.1 μm)
m) were each used.

Example 1 A silver paste was printed on the surface of the PET film by intaglio offset printing to form a square lattice pattern. This pattern was heated and cured in a clean oven (100 ° C.) for 20 minutes to obtain a pattern having a thickness of 7 μm.

Next, the PET on which the above pattern is formed
The film was immersed in an electrolytic copper plating solution (aqueous copper sulfate solution) for electroplating. The electroplating treatment is performed by applying a current of 2 A / dm ³ generated by a rectifier for 20 minutes using metallic copper for the anode and the PET film for the cathode, and forming a thickness on the surface of the pattern made of the silver paste. A 5 μm copper coating was formed.

In this way, a copper film is formed on the surface of the pattern made of the silver paste, and its line width Ws, line interval Wk,
A translucent electromagnetic wave shielding member having an electromagnetic wave shielding pattern in which the film thickness Wt and the ratio Sk / Ss were set to the values shown in Table 1 below was obtained. Example 2 A translucent electromagnetic wave shielding member was obtained in the same manner as in Example 1 except that the line width Ws and the line interval Wk of the electromagnetic wave shielding pattern were changed.

Example 3 Example 1 was repeated except that a copper paste was used instead of the silver paste.
In the same manner as in the above, a light-transmitting electromagnetic wave shielding member was manufactured. Comparative Example 1 A translucent electromagnetic wave shielding member was manufactured in the same manner as in Example 1 described in JP-A-10-163673.

That is, a mixed solution containing a polyvinyl butyral resin and a palladium catalyst was applied to the entire surface of a PET film as a transparent base material, and the surface was further subjected to electroless copper plating to form a copper thin film. Next, a photoresist was applied to the entire surface of the copper thin film, and a grid-like resist pattern was formed by exposure and development. Then, the copper plating film was removed by etching with a ferric chloride / hydrochloric acid aqueous solution, and the resist was peeled off. .

In this way, a translucent electromagnetic wave shielding member having an electromagnetic wave shielding pattern composed of a copper thin film and having the line width Ws, the ratio Sk / Ss, and the film thickness Wt set to the values shown in Table 1 below was obtained. Comparative Example 2 A translucent electromagnetic wave shielding member was obtained in the same manner as in Example 1 except that electroplating was not performed.

Comparative Example 3 A translucent electromagnetic wave shielding member was obtained in the same manner as in Example 3 except that electroplating was not performed. The line width Ws, the line interval Wk, the film thickness Wt, the ratio Sk / Ss and the aperture ratio of the electromagnetic wave shield pattern and the type of the conductive paste, and the type of the metal film formed by the electroless plating in the above-described Examples and Comparative Examples are as follows. , As shown in Table 1 below.

[Evaluation of Physical Properties of Transparent Electromagnetic Wave Shielding Member]
The following physical properties were evaluated for the translucent electromagnetic wave shielding members obtained in the above Examples and Comparative Examples. (Electromagnetic Wave Shielding Effect) A sample of 20 cm × 20 cm was cut out from the electromagnetic wave shielding members obtained in Examples and Comparative Examples, sandwiched in a closed cell, and shielded from electromagnetic waves by the KEC method of Kansai Electronic Industry Promotion Center. The property (shielding effect) was evaluated. In addition, measurement is 0.1-100.
The shielding effect was evaluated in the range up to 0 MHz and the attenuation rate of the electromagnetic wave at 1000 MHz.

The shielding effect of the electromagnetic wave is determined by the attenuation rate (dB).
The larger the better. The evaluation criteria are as follows. A ⁺ : 60 dB or more, very good shielding properties. A: 50 dB or more, less than 60 dB, good electromagnetic wave shielding properties. A ^-: 40 dB or more and less than 50 dB, was practically sufficient shielding property. B: 20 dB or more and less than 40 dB, and the shielding property was insufficient. C: Less than 20 dB, the shielding property was extremely insufficient.

(Visible light transmittance) Using a spectroscopic microscope (“MCPD2000” manufactured by Otsuka Electronics Co., Ltd.), a wavelength of 400 to
Measure the transmittance (%) of 700 nm light (visible light),
The light transmittance was evaluated from the average value. The higher the transmittance, the better the light transmittance. A ⁺ : 90% or more, light transmittance was extremely good. A: 80% or more, less than 90%, good light transmission. A ^-: 70% or more and less than 80%, translucency was practically favorable. B: 50% or more, less than 70%, insufficient light transmission. C: Less than 50%, light transmittance was extremely insufficient.

(Evaluation by visual observation) A translucent electromagnetic wave shielding member was adhered to the forefront of the PDP screen and observed visually.
Evaluation was made according to the following criteria. A: No pattern such as unevenness or mesh could be observed over the entire surface. A ^-: unevenness and mesh were observed faintly. B: Patterns such as unevenness and mesh were observed over the entire surface.

(Comparison of Manufacturing Costs) The cost required for manufacturing the translucent electromagnetic wave shielding member in Example 1 was set to 1, and the ratio of the manufacturing cost by another manufacturing method was determined. Table 1 shows the evaluation results of the respective physical properties of the electromagnetic wave shield pattern portions of the above-mentioned Examples and Comparative Examples.

[0067]

[Table 1]

As is clear from Table 1, the shielding effects of electromagnetic waves were good in Examples 1 to 3, whereas Comparative Example 2 in which the metal coating by electroplating was not provided.
In Nos. 3 and 3, the electromagnetic wave shielding effect was insufficient. Comparative Example 1 in which an electromagnetic wave shielding pattern was formed by copper plating on a transparent substrate and photoetching.
However, although the electromagnetic wave shielding effect, the transmittance, and the visibility were all good, there was a problem that the manufacturing cost was extremely high, 5 to 10 times that of the first embodiment.

[0069]

As described in detail above, according to the present invention,
It is possible to obtain a low-cost electromagnetic wave shielding member which is excellent in the characteristics of the electromagnetic wave shielding effect, translucency, visibility, and viewing angle, and is low in cost.

[Brief description of the drawings]

FIG. 1 (a) is a perspective view showing a translucent electromagnetic wave shielding member, FIG. 1 (b) is an enlarged sectional view of AA part thereof, FIG. 1 (c)
FIG. 3 is a sectional view further enlarging the electromagnetic wave shield pattern 10.

FIG. 2 is a schematic diagram showing an example of a stripe pattern.

FIG. 3 is a schematic diagram illustrating an example of a lattice pattern.

FIG. 4 is a schematic view showing another example of a lattice pattern.

FIGS. 5A to 5C are schematic diagrams showing an example of a pattern formed of a geometric pattern.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent electromagnetic wave shielding member 2 Transparent base material 10 Electromagnetic wave shielding pattern 10a Layer made of conductive paste 10b Metal coating Ws Line width Wk Line spacing Wt Film thickness

Continued on the front page F-term (reference) 2K009 BB24 CC02 CC34 DD02 EE03 4F100 AB01B AB01C AB16C AB17C AB25C AK01B AK42 AR00A BA03 BA07 BA10A BA10C BA32 DE01B EH71C EH712 GB90 HB31B JD08 JG01B JM01K12 AB01 JB02A13A FA01 GA16 5E321 AA04 BB23 BB32 BB41 GG05 GH01 5G435 AA00 AA01 AA16 BB02 BB06 GG33 HH02 HH12 KK07

Claims (4)

[Claims] An electromagnetic wave shield comprising a pattern formed by printing a conductive paste containing a metal powder and a resin on a surface of a transparent substrate, and a metal film formed by electroplating on the surface of the pattern. A transparent electromagnetic wave shielding member having a pattern, wherein the total area Ss of a region where the shield pattern is formed on the surface of the transparent substrate and the total area Sk of a region where the shield pattern is not formed are expressed by the following equation. (1): 1 ≦ Sk / Ss ≦ 9, and the line width Ws of the shield pattern is 5 to 5.
A light-transmitting electromagnetic wave shielding member having a thickness of 40 μm and a thickness Wt of 0.5 to 50 μm. 2. A metal coating comprising at least one metal selected from the group consisting of copper, nickel and gold.
The translucent electromagnetic wave shielding member according to the above. 3. A pattern is formed by printing a conductive paste containing a metal powder and a resin on the surface of a transparent substrate by intaglio offset printing using a blanket having excellent ink release properties, and then forming the pattern. After curing, a metal coating is provided only on the surface of the pattern by electroplating, and the total area Ss of the area of the transparent substrate surface where the electromagnetic wave shield pattern is formed and the entire area of the area where the shield pattern is not formed An electromagnetic wave shielding pattern is formed in which the area Sk satisfies the formula (1): 1 ≦ Sk / Ss ≦ 9, the line width Ws is 5 to 40 μm, and the film thickness Wt is 0.5 to 50 μm. A method for producing a translucent electromagnetic wave shielding member. 4. The method according to claim 3, wherein the surface of the blanket is made of silicone rubber.