JP2000156591A - Composite member for shielding electromagnetic wave and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize perfect tight protection by bonding the surface of an electromagnetic wave shielding sheet provided with a meshed conductive pattern of specified thickness or above on an electric insulating sheet to a protective sheet through a film-like coreless both-sided adhesive material. SOLUTION: The surface of an electromagnetic wave shielding sheet provided with a meshed conductive pattern of 3 μm thick or above on an electric insulating sheet is bonded to a protective sheet through a film-like coreless both-sided adhesive material. When the conductive face of the electromagnetic wave shielding sheet is protected by bonding the protective sheet through a film-like coreless both-sided adhesive material, the conductive pattern face can be protected perfectly and durbly. When it is applied to a rigid and planar object of large size, it can be completed as one panel supporting the electromagnetic wave shielding sheet itself.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite member for electromagnetic wave shielding and a method of manufacturing the same. More particularly, the member is obtained by adhesively polymerizing an electromagnetic wave shielding sheet having a mesh-like conductive pattern and a protective sheet. About what will be. When the member is transparent, it is effectively used, for example, as an electromagnetic wave shielding filter of a plasma display (hereinafter referred to as PDP).

[0002]

2. Description of the Related Art Electromagnetic waves emitted from various electronic information devices have been problematic because they may cause malfunctions between electronic devices or adversely affect the human body. Various studies have been conducted to solve this problem. It has been done. For example, in a PDP that has attracted attention as a next-generation large-sized TV, a strong electromagnetic wave is radiated from the screen due to its light emitting principle. Therefore, a method under study to prevent this is to attach an electromagnetic wave shielding filter to the front of the screen.

[0003] In general, the means for shielding electromagnetic waves differs depending on the target electronic information equipment. In particular, in such equipment in which the inside or the screen can be visually recognized and the electromagnetic waves need to be shielded, the following methods are generally used. An electromagnetic wave shielding member manufactured by various means is used. (1) A copper foil is laminated on an electrically insulating transparent sheet (transparent sheet made of plastic or glass) and processed by a photo-etching method to form a mesh-shaped copper conductive pattern. (2) A copper conductive pattern is formed on the transparent sheet by electrolytic plating of copper, and the resultant is processed by a photo-etching method. (3) A mesh fabric of fibers obtained by plating copper, nickel, silver, or the like on the surface, directly or another on the transparent sheet.
And a sheet fixed between two transparent sheets.

The obtained electromagnetic wave shielding member is rarely used as it is, and a step of protecting the conductive pattern surface is provided first. As the protection step, for example, a thin film such as ITO (indium tin oxide) or silicon oxide is coated on the entire surface by a thin film forming means such as sputtering, or a hardening resin is coated on the entire surface. For example, using the same or different sheet of the electrically insulating transparent sheet on which the conductive pattern is formed, the sheet itself is laminated on the conductive pattern surface via an adhesive (liquid) (this method is called a laminating method). .

[0005] In particular, the laminating method is a step applied when the electromagnetic wave shielding member itself is flexible, has a relatively large size such as a PDP, and is used in a state like one panel. It is effective to have the function of supporting the member itself at the same time as protecting the pattern.

[0006]

In the electromagnetic wave shielding member formed by the above-mentioned laminating method, the high transparency which is originally considered to be deteriorated especially in applications such as PDP which requires higher transparency. There is a problem that tends to be seen. This was thought to be due to entrapped air bubbles by the adhesive used for laminating the transparent protective sheet, or to local adhesion failure. This is also a significant factor in obtaining a particularly effective electromagnetic wave shielding property, and the tendency of the pattern to decrease is large for a certain or more high-thickness pattern of the conductive pattern.

[0007] In view of the above problems, the present inventors have conducted intensive studies to solve the problems, and as a result, have found a means of solving the problems one by one and have reached the present invention. The solution is as follows.

[0008]

That is, the present invention provides a composite member for shielding electromagnetic waves and a method for manufacturing the same. An electromagnetic wave shielding sheet provided with a mesh-like conductive pattern having a thickness of 3 μm or more is characterized in that the conductive pattern surface and the protective sheet are adhesively polymerized with a film-like core material-less double-sided adhesive. Things.

The composite member for shielding electromagnetic waves according to the first aspect is manufactured by the method according to the second aspect. That is, when a protective sheet is adhered and polymerized to an electromagnetic wave shielding sheet having a mesh-shaped conductive pattern having a thickness of 3 μm or more provided on an electric insulating sheet to produce a composite member for electromagnetic wave shielding, first, After the conductive pattern surface and the protective sheet surface are preliminarily adhered to each other with a film-like core material-less double-sided adhesive, this is left in a pressurized atmosphere. It is to be noted that the manufacturing method is, of course, claimed in claim 1.
It does not specify the composite member for electromagnetic wave shielding of
It is provided as one effective manufacturing mode.

[0010] Claims 1 and 2 provide Claims 3 to 5 as preferred embodiments, and Claim 2 provides Claim 6 together as dependent inventions. Hereinafter, the present invention will be described in more detail in the next section.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an electric insulating sheet of a substrate provided with a mesh-shaped conductive pattern having a thickness of 3 μm or more and a protective sheet adhesively polymerized on the surface of the conductive pattern are generally made of glass or plastic. It is a sheet material of about 0.05 to 10 mm, and its transparency is determined by the target electronic information equipment and the purpose of use. In some cases, it may be opaque; In some cases, it may be necessary. Thus, where it may be opaque, there are ceramics and colored glass or plastic sheets.

The thickness of about 0.05 to 10 mm is set in consideration of the required characteristics of the finally obtained electromagnetic wave shielding member, the steps leading up to its manufacture, and the like. Select a sheet with a rigidity of about 1 to 10 mm and a plate-like thickness, and select an electrically insulating sheet from a film with a thickness of about 0.05 to 0.5 mm. It is desirable to do.

When the electric insulating sheet is made of plastic, generally, polymethyl methacrylate, polystyrene or a copolymer of styrene and acrylonitrile or methyl methacrylate, poly (4-methylpentene-1) , Polypropylene, cyclopentene, norbonene, tetracyclododecane, etc., or an amorphous cyclic olefin polymer alone or copolymerized with ethylene, etc. Polymers or the like are used. Of course, it is not limited to these, and even if they are selected from among these examples and further from other examples, dimensional stability, impact strength, chemical resistance, weather resistance, etc., mainly the transparency If necessary, the best one will be selected on the premise that it is more transparent.

A mesh-like conductive pattern is provided on the insulating sheet. When setting the conductive pattern, a pattern is designed so that electromagnetic waves are most effectively shielded. If transparency is required, the aperture ratio, the adhesion of the conductive pattern to the sheet, the ease of manufacturing, and the like are also taken into consideration. Here, in particular, the shielding efficiency of the electromagnetic wave depends on the type of the conductive material, the shape of the formed pattern, the thickness, the line width, and the aperture ratio (determined by the shape and the line width). In other words, using a conductive material having the lowest electric resistance (generally, 10-3 Ω · cm or less), a higher-density pattern shape (either increase the line width or decrease the line width and increase the number of lines) Therefore, it is better to design with a thicker pattern. Here, the conductive material is generally gold, silver, or copper is good, but for a higher-density pattern shape, especially when transparency is also required, it is necessary to consider the aperture ratio, The pattern density (shape) is determined by itself. Therefore, the only means is to increase the thickness of the formed pattern.

Regarding the thickness of the formed pattern, regardless of the presence or absence of transparency, any formed pattern must have a thickness of 3 μm or more, preferably 5 μm or more in order to effectively shield electromagnetic waves. This is because it is necessary to shield a wide range of electromagnetic waves as much as possible. For example, a PDP is required to clear, for example, VCCI regulations by shielding electromagnetic waves in a band of 10 to 100 MHz. Therefore, it is difficult to obtain a satisfactory electromagnetic wave shielding composite member with a thin thickness pattern of less than 3 μm. Incidentally, it is sufficient that the upper limit of the thickness is up to 50 μm. This is because even if the thickness is more than 50 μm, further improvement of the shielding effect cannot be expected.

When transparency is required, such as PDP, it is desirable to form a conductive pattern under the following conditions. That is, when the thickness is 3 μm or more, the line width is 1 to 25 μm.
m, and a grid pattern so that the aperture ratio is 56 to 96%, transparent (total light transmittance of 50% or more)
Formed on a flexible resin sheet. By setting in this way, the screen can be seen clearly while effectively shielding the electromagnetic waves.

The means for forming the mesh-like conductive pattern is not particularly limited. Generally, according to the means (1) to (3) described in the section of the prior art, in particular, a method of electrolytically plating and photoetching copper using copper described in (2) is, for example, an electric insulating method Electroless plating of copper is performed on the sheet, and copper is electrolytically plated thereon with a thickness of 3 μm or more. Then, photolithography is performed using a mask having a desired pattern, and the non-patterned portion is removed by etching with an acid.
This method of pattern formation is desirable because it can produce finer patterns more accurately than other methods, but the electroless plating layer of copper has poor adhesion to the electrical insulating sheet that is the base. There is a high possibility that the formed copper pattern will peel off.

Therefore, it is more preferable that the copper underlayer formed by electroless plating of copper be replaced with a physical thin film forming means represented by a sputtering method. According to this method, it can be formed on the electric insulating sheet surface directly and quickly in a dry state with sufficient adhesion. Therefore, since the copper layer formed by electroplating on this layer has a sufficient adhesive force with a thickness of 3 μm or more, there is little possibility that the fine pattern is peeled off from the sheet surface.

The formed mesh-shaped conductive pattern having a size of 3 μm or more is generally colored on its surface with a color different from its own color. This is because transparency is particularly required, and coloring the surface is more effective in increasing visibility and contrast and preventing the eyes from feeling tired. Generally, the different colors are brown to black. As for the coloring means, there are a chemical method and a method of simply coating a colored resin. Here, in the chemical method, for example, the copper surface of the pattern is treated with an oxidizing agent (for example, an aqueous solution mainly containing sodium chlorite) or a sulfurizing agent (an aqueous solution mainly containing sulfur or potassium sulfide).
Each of the copper surfaces changes into copper oxide or copper sulfide and is colored. This chemical method has higher coloring freshness than coating with other coloring resin and the like, and is excellent in quality because it is formed integrally with copper.

The electromagnetic wave shielding sheet having a mesh-like conductive pattern having a thickness of 3 μm or more and obtained by the above-mentioned contents can be used for practical purposes by protecting the conductive pattern surface by some means. In the present invention, however, this is achieved particularly by using the above-mentioned protective sheet and bonding and polymerizing it with a film-like core-less double-sided adhesive (hereinafter, referred to as FL adhesive).

Here, by using a sheet made of the above-mentioned resin or the like for the protection, the conductive pattern surface can be completely and durably protected, and particularly, it is rigid, flat, and large in size. For use in a required PDP or the like, the electromagnetic wave shielding sheet itself is supported, and the panel can be completed as one panel.

In addition, since both of the above are bonded and polymerized particularly with an FL adhesive, not only for a conductive pattern having a thickness of 3 μm or more, but also various mesh pattern shapes (square shape). , Rectangular, rhombic lattice-like patterns, triangles, hexagons, circles, etc.) without causing bubbles or local adhesion failure, and can be completely adhered. In addition, with only core material, that is, adhesive material only, it is processed into a film shape, especially for those requiring transparency,
Core material (generally polyester film, polyethylene film, polypropylene film, paper,
(A nonwoven fabric is used.) There is no factor of lowering the transparency by itself. It is considered that the absence of bubbles and the occurrence of local adhesion failure do not occur because the FL adhesive itself has a function of being easy to move because there is no core material. Also, unlike a liquid adhesive, since it is in a film-like solid state, there is little variation in the quality of the obtained electromagnetic shielding composite member, that is, there is no image distortion because the film thickness is easily controlled to be constant, and There is an effect that the manufacturing process can be easily controlled.

The thickness of the FL adhesive is preferably as thin as possible for those requiring transparency. However, in order to perform complete adhesion without defects, the thickness of the conductive pattern is required. It is necessary to consider the shape, shape, and even the workability. Taking such conditions into account, specifically 5μ
m to 2 mm, preferably 10 to 150 μm, and even 20
It is better to select it appropriately in the range of ６０60 μm.

In addition, the protective sheet is not limited to a single sheet, and may be a composite sheet of different kinds. There is no particular limitation as long as UV protection processing, surface reflection prevention processing, antistatic processing and the like have been performed.

The type of the adhesive used for the FL adhesive is preferably an adhesive which can be easily processed into a film, such as an acrylic or silicone adhesive. Further, a near-infrared ray inhibitor, an ultraviolet ray inhibitor, an antistatic agent and the like may be kneaded into the adhesive, and there is no limitation.

Next, a method of manufacturing the composite member for electromagnetic wave shielding having the above-described structure will be described. This manufacturing method is completed in two steps. First, in one step, the mesh conductive pattern surface having a thickness of 3 μm or more provided on the insulating sheet and the protective sheet surface are preliminarily bonded with an FL adhesive. The meaning of the pre-sticking is sticking by other means except for leaving in a high-pressure atmosphere in the next step (final). Therefore, it is a simple physical means generally performed. Specifically, for example, while pulling out a roll-wound FL adhesive through a guide roll, first, a mesh-like conductive material of the electric insulating sheet is drawn out. The entire surface is adhered while rolling on the pattern surface or the protective sheet surface, and then one of the two is adhered while being polymerized via a nip roller. This pre-sticking step is necessary in order to quickly and easily perform the next standing step in a high-pressure atmosphere and obtain a defect-free composite member.

Therefore, it is necessary to completely eliminate the drawbacks of air bubble engulfment and local adhesion failure caused by the above-mentioned pre-sticking, and this is left in a pressurized atmosphere which is the next step. It can be achieved. In this step, specifically, first, the above-mentioned adhesive composite sheet is subjected to about 1 to 1
0 kg / cm ^2, preferably 2~8kg / cm ^2, further from about 5 to a pressure vessel pressurized to 3~6kg / cm ²
Leave for 60 minutes. By simply leaving the device in this state, not only the internal fine bubbles but also the local adhesion failure completely disappear. Here, the numerical content of the high pressure is about 1 to 10 kg /
cm ² , which is exemplified because the elimination efficiency varies depending on the state of the two inherent defects (bubbles and the degree of local adhesion failure) and the like. Yes, but it is not specified as it may need to be less than 1 kg / cm ^{2 or} more than 10 kg / cm ² . In addition, when left, the inside of the pressurized container may be heated. This is because there is a case where the above-mentioned disadvantage elimination is effective to progress more quickly. However, even when heating, it is preferable not to exceed the heat resistant temperature of each material, and it is usually room temperature to 60 ° C. As described above, this step is particularly effective for those having a conductive pattern having a thickness of 3 μm or more, and is more effective when the pattern is fine and complicated. This is because, in the pre-sticking step, when these are fine and complicated, bubbles are more likely to be entrapped.

In consideration of the fact that the effect of the present invention cannot be obtained by other means, it is considered that the effect is achieved by a specific action, but the mechanism is not clear. That is, even if the same two steps of the present invention are performed by using other means, for example, a liquid adhesive instead of the FL adhesive, the disadvantages of air bubbles and local adhesion failure are not completely eliminated. , There is a tendency for air bubbles to be entrapped. This is considered to be due to uneven coating thickness and a small amount of solvent remaining. Further, when the same two steps as in the present invention are performed using a film adhesive having a core material instead of the FL adhesive, the two disadvantages are not completely solved.
This is presumably because the intermediate material interposed in the middle limits the degree of freedom of movement of the adhesive itself, and does not eliminate any disadvantages.

Incidentally, the electromagnetic wave cannot be effectively shielded unless electric charges are released by grounding the conductive pattern. Therefore, it is necessary to provide an earth electrode. Although the shape and method are not particularly limited, for example, a method in which the film end is folded, a method in which the film end is processed by applying silver paste or a copper foil tape, and the method of polymerizing and bonding so that the FL adhesive does not interfere with the method are preferable. Is desired.

[0030]

The present invention will be described in more detail with reference to the following examples together with comparative examples. (Example 1) First, an electromagnetic wave shielding sheet provided with a mesh-shaped conductive pattern having a thickness of 3 µm or more was produced as follows. Thickness 125μm, size 770 × 1
One surface of a biaxially stretched polyethylene terephthalate film (hereinafter referred to as a PET film) having a total light transmittance of 200 mm and a total light transmittance of 90% is subjected to pretreatment (adhesion improvement) by glow discharge,
Using this as a target of copper, a copper thin film having a thickness of 0.12 μm was formed with a magnetron sputtering apparatus. Then, a negative photoresist as a photosensitive resin was uniformly coated on the copper thin film layer with a thickness of 10 μm, and then photolithography was performed using a mask having a square grid pattern image with a line width of 15 μm and a pitch of 200 μm. Then, copper electrolytic plating was performed, and a copper thick film layer having a thickness of 8 μm was laminated only on the pattern portion. After that, the resist was peeled off, and the entire copper thin film layer in the non-pattern portion was removed by etching. The obtained copper pattern had a thickness of 7.8 μm and an aperture ratio of 86%.

Next, the copper pattern is immersed in a sulfurizing bath (40 ° C. for 60 seconds) containing sulfur as a main component, and adding lime, casein, and potassium sulfide as an auxiliary agent thereto to form an aqueous solution.
It was immediately taken out, washed and dried. The surface layer was changed to copper sulfide and colored dark black.

The colored electromagnetic wave shielding sheet thus obtained was adhesively polymerized with a protective sheet by the following method to produce a desired composite member for electromagnetic wave shielding.

First, preliminary bonding was performed as follows. 3.2mm thick, 960x540m as protective sheet
m tempered glass plate (total light transmittance 94%)
A 45 μm thick coreless acrylic double-sided adhesive (LSI 31B manufactured by Lintec) (sandwiched with a double-sided release film) was roll-bonded to one side of the roll under constant pressure with a roll, and the above-obtained product was obtained thereon. The grid-like copper pattern surface of the electromagnetic wave shielding sheet was roll-bonded under a constant pressure, and both were preliminarily polymerized and bonded (referred to as a pre-laminate sheet).

When the preliminary adhesive sheet was observed with a magnifying microscope (magnification: 500), bubbles having a size of about 10 to 100 μm were scattered in the lattice over almost the entire surface. Therefore, further attempts were made to strengthen the preliminary bonding by passing between the nip rollers set at twice the strength of the constant pressure performed above. When this was again observed with a magnifying microscope, the size of the bubbles was slightly smaller and smaller, but was still scattered. Although the overall transparency was judged visually, it was cloudy and lacked sharpness. The above results indicate that the problem cannot be solved by the pre-sticking means.

Then, the pre-adhered sheet obtained by the two rolling-adhesions was placed in a high-pressure container and the whole was pressed under the following conditions. In other words, the inside of the high pressure vessel is heated to 40 ° C.
A pressure of 5 kg / cm ² was applied and left for 30 minutes. When taken out after opening and observed with a magnifying microscope, fine bubbles scattered in the pre-adhered sheet were completely disappeared, and the transparency was dramatically improved. The composite material thus obtained is a transparent composite plate of extremely high quality, which can be clearly seen, for example, placed on the front of a PDP, while effectively shielding electromagnetic waves.

For example, the glass screen of a PDP module itself may be used as a protective sheet, and an electromagnetic wave shielding sheet may be directly bonded and polymerized in the same process. In the case of such a means, it is not necessary to install the device on the front surface as described above.

(Comparative Example 1) (When the thickness of the mesh-shaped conductive pattern is less than 3 μm) First, according to Example 1, an electromagnetic wave shielding sheet was produced. However, the thickness of the copper thick film layer formed by electrolytic plating laminated on the copper thin film layer was 2 μm.

Then, the electromagnetic wave shielding sheet and the glass protective plate were preliminarily adhered to each other through a coreless double-sided adhesive under the same prelaminating conditions as in Example 1. The obtained preliminary composite plate was observed with a magnifying microscope in the same manner as in Example 1. As a result, there were almost no microbubbles as observed in Example 1, and substantially different from the composite member for electromagnetic wave shielding obtained by standing in a pressurized atmosphere further performed in Example 1. Did not. In other words, this result indicates that if the thickness of the conductive pattern is less than 3 μm, the leaving operation in the pressurized atmosphere as in the present invention is not necessary. LS13
Instead of 1B, a preliminary double-adhesion was carried out using a silicone-based double-sided adhesive material (thickness: 100 μm) having a core material. In this case, however, trapping of air bubbles was not substantially confirmed. . If it is less than 3 μm, there is no difference by other means. However, if it is less than 3 μm, for example, P
It goes without saying that the high electromagnetic wave shielding ability required by DP cannot be obtained.

[0039]

The present invention has the following effects because it is configured as described above.

For a mesh-like conductive pattern having a thickness of 3 μm or more, which is particularly necessary for effectively shielding electromagnetic waves,
In order to protect the pattern, especially with a protective sheet, through a film coreless double-sided adhesive,
It has become possible to obtain a composite member for electromagnetic wave shielding that is completely adhered and protected without any trapping of air bubbles or local adhesion failure.

With respect to transparency, which is a necessary condition for shielding electromagnetic waves from a PDP or the like, a double-sided adhesive material without a core material and free of the above-mentioned embracing of bubbles and local adhesion failure is used. As a result, these factors no longer reduced transparency.

Since the bonding between the mesh-shaped conductive pattern surface and the protective sheet is not performed by a liquid adhesive, a member for electromagnetic wave shielding can be obtained quickly and with less variation in quality by a simple manufacturing process. That you can do it.

In addition to PDPs and CRTs, it is more effective to shield electromagnetic waves from electronic information equipment that emits electromagnetic waves by itself, and from equipment that does not emit light by itself but causes malfunctions when received from others. Now available.

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 4F100 AB17 AB17B AG00 AG00A AG00C AK01A AK01C AK25G AK42 AT00A BA02 BA03 BA07 BA10A BA10C CB00 DC16B EC182 EH66 EH71 EJ15 EJ172 EJ38 GB41 JA20A JA20B01J01G01 BB23 BB41 BB44 CC16 GG05 GH01

Claims (6)

[Claims] 1. An electromagnetic wave shielding sheet comprising an electric insulating sheet as a base and a mesh-like conductive pattern having a thickness of 3 μm or more provided thereon, wherein the conductive pattern surface and the protective sheet are free of a film-like core material. A composite member for electromagnetic wave shielding characterized by being adhesively polymerized with a double-sided adhesive. 2. A composite member for electromagnetic wave shielding is produced by bonding and polymerizing a protective sheet on an electromagnetic wave shielding sheet having an electric insulating sheet as a substrate and a mesh-like conductive pattern having a thickness of 3 μm or more provided thereon. 2. The method according to claim 1, wherein the conductive pattern surface and the protective sheet surface are first preliminarily bonded with a film-shaped core-less double-sided adhesive material, and then left under a pressurized atmosphere. A method for manufacturing a composite member for electromagnetic wave shielding. 3. The electric insulating sheet according to claim 1, wherein the electric insulating sheet and the protective sheet are transparent sheets made of plastic or glass, and the protective sheet is a transparent sheet thicker than the electric insulating sheet. A composite member for electromagnetic wave shielding according to the above or a method for producing the same. 4. The grid-like conductive pattern according to claim 1, wherein the mesh-like conductive pattern is a copper-like conductive pattern formed by laminating a copper thin film layer on a copper thin film layer as a base. A composite member for electromagnetic wave shielding or a method for producing the same. 5. The composite member for electromagnetic wave shielding according to claim 1, wherein the thickness of the film-like core material-less double-sided adhesive is 5 μm to 500 μm. 6. The pressure atmosphere is 1 to 10 kg / cm.
^The method for producing a composite member for electromagnetic wave shielding according to claim 2, wherein the composite member is in a high-pressure container.