JP5104015B2 - Metal mesh sheet for shielding electromagnetic wave and method for producing the same - Google Patents

Description

  The present invention relates to an electromagnetic wave shielding metal mesh sheet provided on a front plate of a plasma display and provided with a metal mesh on a polymer sheet, and a method for producing the same.

  Gas discharge display devices used for image display, for example, plasma display panels (PDPs), when a voltage is applied between electrodes, gas molecules enclosed inside are excited by the discharge caused by the application, and encapsulated in the generated ultraviolet light. Excites rare fluorescent materials. At this time, a light beam in the visible light region is generated to display an image, but electromagnetic waves are generated by this discharge, and a slight amount of electromagnetic waves are leaked to the outside. In order to shield this electromagnetic wave, this function is provided in the filter installed on the front plate of the plasma display. In order to obtain this shielding function, for example, a polyethylene terephthalate (PET) film laminated with a conductive metal film formed in a mesh shape can be achieved. The conductive metal mesh covers the frequency range to be shielded and the width and spacing of the metal mesh grid are optimally set so as not to disturb the image light. The metal mesh is connected to the PDP housing and induced by electromagnetic waves. The generated charge is removed by grounding. The PDP pixel matrix and the metal mesh overlap, and the direction of the metal mesh is set obliquely as shown in FIG. 1 so as not to disturb the generation of moire fringes and image light. Patent Documents 1 and 2 will be described as conventional examples of filters effective for shielding such electromagnetic waves.

  In Patent Document 1, in order to shield the electromagnetic wave generated from the entire surface of a screen such as a liquid crystal screen and a CRT while ensuring visibility, a mesh-like pattern made of silver paste is screen printed on a transparent resin substrate by a line width of 30. An electromagnetic wave cut filter characterized by being formed in a range of 80 to 90% at an aperture ratio of ˜50 μm is disclosed.

In Patent Document 2, a register mark for detecting a position is used as a light projecting portion provided in a frame portion, and even if the area of the light projecting portion is large, the light projecting portion has a geometric shape such as a mesh shape, a dot shape, or a slit shape. An electromagnetic wave shielding sheet is disclosed that can be cut with high positional accuracy by leaving a metal layer with a geometric pattern, which is difficult to block during production and storage.
JP-A-2005-243661 Japanese Patent Laid-Open No. 2005-11994

When a metal thin film is bonded onto a polymer sheet via an adhesive layer and this metal thin film is processed into a mesh shape by photolithography to produce a metal mesh sheet for electromagnetic wave shielding, In order to improve the adhesion to the metal thin film, there is a step of aging in a heated atmosphere of 50 to 80 ° C. However, since the thermal expansion coefficients of the polymer sheet and the metal thin film are different, there is a problem that deformation occurs between the two due to aging in a heated atmosphere at 50 to 80 ° C., resulting in a decrease in production yield.
Therefore, even if the object of the present invention is to approximate the physical properties such as elongation of the polymer sheet and the metal thin film as much as possible and perform the above aging in a heating atmosphere at 50 to 80 ° C., the result of distortion and the like is not generated. An object of the present invention is to provide a metal mesh sheet for shielding electromagnetic waves and a method for producing the same.

As a result of intensive studies, the present inventor was able to solve the above problems by controlling the orientation of the copper crystals in the metal mesh.
The invention according to claim 1 is provided on the front plate of the plasma display, and in the metal mesh sheet for shielding electromagnetic waves, comprising a metal mesh on the polymer sheet,
The polymer sheet is made of polyethylene terephthalate, polycarbonate, or polymethyl methacrylate,
The polymer sheet and the metal mesh are aged after bonding through an adhesive layer,
The metal characterized in that the metal mesh is made of a copper mesh, and the copper mesh has columnar crystals of (110) orientation, thereby preventing distortion of the polymer sheet of the sheet during the aging. It is a mesh sheet.
The invention according to claim 2 is characterized in that the metal mesh has a line pitch of 20 to 50 μm, a line width of 8 to 20 μm, and a bias angle of 40 to 60 °. It is a metal mesh sheet.
The invention according to claim 3 is provided in the front plate of the plasma display, and in the method for producing an electromagnetic wave shielding metal mesh sheet comprising a metal mesh on a polymer sheet,
A step of providing an adhesive layer on the polymer sheet; a step of laminating a copper thin film obtained by electrodeposition on the adhesive layer; a step of aging after the step of laminating; and the copper thin film. The polymer sheet is made of polyethylene terephthalate, polycarbonate, or polymethylmethacrylate, and the copper thin film obtained by the electrodeposition has a (110) orientation. It is a manufacturing method of the metal mesh sheet | seat characterized by having a columnar crystal.

  According to the present invention, the physical properties such as the elongation ratio of the polymer sheet and the metal thin film are approximated as much as possible, and even if the aging is performed in a heated atmosphere at 50 to 80 ° C., the result such as distortion is not generated. A metal mesh sheet for shielding electromagnetic waves and a method for producing the same can be provided.

Hereinafter, the present invention will be described in more detail.
2 and 3 are views showing the steps of the method for producing a metal mesh sheet for shielding electromagnetic waves according to the present invention, FIG. 2 is a sectional view, and FIG. 3 is a plan view.

A copper thin film 2 is laminated on the polymer sheet 1. This lamination can be achieved by forming a transparent adhesive layer on the polymer sheet 1 and then laminating the copper thin film 2.
Next, a metal mesh is produced by photolithography. The surface of the copper thin film 2 is covered with an etching resist 3 and patterned. The metal mesh sheet of the present invention has a metal mesh line pitch of 20 to 50 μm, a line width of 8 to 20 μm, because the mesh shape is difficult to be visually recognized when provided on a display and has sufficient electromagnetic wave shielding ability. In addition, the bias angle is desirably in the range of 40 to 60 °. FIG. 4 shows the line pitch and the bias angle. The line pitch is a distance between fine lines of the metal mesh. The bias angle is an inclination angle of the thin line with respect to the length direction of the metal mesh sheet. The resist type and patterning method are selected according to the above specifications. A general method is to coat a photosensitive dry film resist or liquid resist, and to expose and develop through a photomask.

  Next, the copper thin film 2 is developed to form a copper mesh pattern. Development can be performed using an alkaline aqueous solution.

  Subsequently, the surface of the formed copper mesh pattern may be blackened (reference numeral 4). It is desirable that the surface is degreased and chemically roughened as the immediately preceding treatment. By blackening, the light transmittance is appropriately adjusted, and the visibility of the plasma display image is improved. The blackening method is not particularly limited, and a known method can be appropriately selected.

  As the polymer sheet 1 used in the present invention, polyester (PE), polyethylene terephthalate (PET), polycarbonate (PC), polyvinyl alcohol (PVA), polyethylene (PE), polymethyl methacrylate (PMMA), polystyrene (PS) Polyurethane (PU), triacetylrose (TAC), cellophane, ethylene-vinyl acetate copolymer, and the like can be used. Among these, a sheet made of PET, PC, PMMA, or the like can be preferably used.

  As the adhesive layer, any of a thermosetting type and a photosetting type such as an epoxy-based and urethane-based one having an ethylene-vinyl acetate copolymer as a main component can be used.

  The present invention is characterized in that the copper thin film has columnar crystals of (110) orientation. The (110) orientation here means that the diffraction of the (110) plane is the strongest in the X-ray diffraction as compared with the non-oriented crystal. Therefore, it can be said that the copper thin film having columnar crystals of (110) orientation is oriented in the thickness direction with the crystal grains in the copper thin film being gathered together. Such columnar crystals can be produced by changing conditions such as current density in electrodeposition, plating bath temperature, and additives added to the plating bath. For example, the additive includes a brightener (sulfur compound). The columnar crystals can be produced by adding the additive to the plating bath in the degree (quantitative relationship) described in the following examples. In the present invention, all copper crystals need not be columnar crystals. Although it is considered that the copper crystal has various orientations in the copper thin film, in the present invention, the columnar crystal only needs to be the most quantitatively in the copper thin film.

  As a method for bonding the polymer sheet and the copper thin film, there are methods such as heat crosslinking and photocrosslinking. Adhesion by heat crosslinking is usually performed at a temperature of 80 to 140 ° C. for 20 to 60 minutes, depending on the type of adhesive. For adhesion by photocrosslinking, a light source that emits light in the ultraviolet to visible region can be used. For example, high pressure, low pressure mercury lamp, halogen lamp, incandescent lamp, and the like can be mentioned, and high pressure mercury lamp is most suitable.

The pressure applied at the time of adhesion is usually in the range of 10 to 100 Kg / cm ² , preferably 20 to 50 Kg / cm ² .

  In the present invention, in order to make the adhesion between the polymer sheet and the copper thin film more reliable, aging is further performed in a heated atmosphere at 50 to 80 ° C. The aging time is 48 to 96 hours, for example. In the present invention, since the orientation direction of the copper crystal in the copper thin film is specified, the physical properties such as the elongation ratio of the polymer sheet and the copper thin film are approximated. Does not occur.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not restrict | limited to the following example.

Example 1
First, a copper thin film was prepared by copper sulfate plating. The bath composition is copper sulfate pentahydrate 200-230 g / L, sulfuric acid 40-80 g / L, and chlorine ions 80-120 mg / L dissolved in ion-exchanged water. The compound (Bis (3-sulfopropyl) disulfide disodium salt (SPS)) was added in an amount of 10 to 20 mg / L, the bath temperature was set to 30 ° C., and the plating was performed on the cylindrical drum so that the plating thickness was about 5 to 25 μm. This drum was subjected to a metal peeling treatment with a chromate solution in advance, and a peeling surface was put into a surface length method with a cutter after plating, and peeling was performed by winding. When the crystal orientation of the plating film was examined by an X-ray diffractometer, it showed a strong (110) orientation and was a columnar crystal in the thickness direction.
FIG. 5 shows a photograph of a cross-sectional structure etched by Focused Ion Beam (FIB) of columnar crystals of the copper thin film of Example 1.

Next, on the PET sheet, a thermosetting polyurethane adhesive was uniformly applied and dried, and the copper thin film prepared above was placed on the PET sheet while applying pressure in the range of 20 to 50 Kg / cm ² . Heated to 80-100 ° C for about 2 hours. Next, in order to improve the adhesion between the copper thin film and the PET sheet, aging was performed at 60 ° C. for 72 hours. Further, a negative resist film was thermocompression bonded onto the copper thin film. Thereafter, exposure was performed with a predetermined bias angle by a YAG laser. Next, it developed with the alkali developing solution and produced the mesh sheet using the copper chloride etching liquid. Thereafter, a sulfur compound was added to the copper sulfate nickel plating solution, and known black plating was performed to produce a metal mesh sheet for shielding electromagnetic waves. The metal mesh had a line pitch of 30 μm, a line width of 15 μm, and a bias angle of 50 °.

  The metal mesh sheet produced in this way was able to suppress the occurrence of a dent-like defect with a small depth and to improve the final yield.

Comparative Example 1
First, a copper thin film was prepared by copper sulfate plating. The bath composition is copper sulfate pentahydrate 200-230 g / L, sulfuric acid 40-80 g / L, and chlorine ions 80-120 mg / L dissolved in ion-exchanged water. About 200 mg / L of a certain polyethylene glycol (PEG) was added, the bath temperature was set to 30 ° C., and the drum was plated to have a plating thickness of about 5 to 25 μm. The drum was previously subjected to a metal peeling treatment with a chromate solution or the like, and after the plating, a peeling surface was put into a surface length method by a cutter, and peeling was performed by winding. When the crystal orientation of this plating film was examined with an X-ray diffractometer, it showed a weak (100) orientation, and it was a randomly oriented crystal without a columnar shape in the cross section.
FIG. 6 shows a photograph of a cross-sectional structure etched by Focused Ion Beam (FIB) of the columnar crystal of the copper thin film of Comparative Example 1.

Next, on the PET sheet, a thermosetting polyurethane adhesive was uniformly applied and dried, and the copper thin film prepared above was placed on the PET sheet while applying pressure in the range of 20 to 50 Kg / cm ² . Heated to 80-100 ° C for about 2 hours. Next, in order to improve the adhesion between the copper thin film and the PET sheet, aging was performed at 60 ° C. for 72 hours. Further, a negative resist film was thermocompression bonded onto the copper thin film. Thereafter, exposure was performed with a predetermined bias angle by a YAG laser. Next, it developed with the alkali developing solution and produced the mesh sheet using the copper chloride etching liquid. Thereafter, a sulfur compound was added to the copper sulfate nickel plating solution, and known black plating was performed to produce a metal mesh sheet for shielding electromagnetic waves.
The metal mesh had a line pitch of 30 μm, a line width of 15 μm, and a bias angle of 50 °.

  The metal mesh sheet produced in this way could not suppress the occurrence of a dent-like defect with a small depth, and the final yield was lowered.

  As described above, the metal mesh sheet of the present invention can be used as a filter for shielding electromagnetic waves generated from a PDP screen or a liquid crystal screen, and can be used by being installed at a location where electromagnetic waves are generated.

It is a figure which shows the directionality of a metal mesh. It is a figure (sectional drawing) for demonstrating the manufacturing method of the metal mesh sheet for electromagnetic wave shielding of this invention. It is a figure (plan view) for demonstrating the manufacturing method of the metal mesh sheet for electromagnetic wave shielding of this invention. It is a figure for demonstrating a line pitch and a bias angle. It is a figure which shows the cross-sectional structure | tissue photograph etched by Focused Ion Beam (FIB) of the columnar crystal of the copper thin film of Example 1. FIG. It is a figure which shows the cross-sectional structure | tissue photograph etched by Focused Ion Beam (FIB) of the columnar crystal of the copper thin film of the comparative example 1.

Claims (3)

In the metal mesh sheet for shielding electromagnetic waves, which is provided on the front plate of the plasma display and provided with a metal mesh on the polymer sheet,
The polymer sheet is made of polyethylene terephthalate, polycarbonate, or polymethyl methacrylate,
The polymer sheet and the metal mesh are aged after bonding through an adhesive layer,
The metal characterized in that the metal mesh is made of a copper mesh, and the copper mesh has columnar crystals of (110) orientation, thereby preventing distortion of the polymer sheet of the sheet during the aging. Mesh sheet.   2. The metal mesh sheet according to claim 1, wherein the metal mesh has a line pitch of 20 to 50 [mu] m, a line width of 8 to 20 [mu] m, and a bias angle of 40 to 60 [deg.]. In the method for producing a metal mesh sheet for shielding electromagnetic waves, which is provided on the front plate of the plasma display and provided with a metal mesh on the polymer sheet,
A step of providing an adhesive layer on the polymer sheet; a step of laminating a copper thin film obtained by electrodeposition on the adhesive layer; a step of aging after the step of laminating; and the copper thin film. The polymer sheet is made of polyethylene terephthalate, polycarbonate, or polymethylmethacrylate, and the copper thin film obtained by the electrodeposition has a (110) orientation. A method for producing a metal mesh sheet, comprising columnar crystals.

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