KR100579006B1 - Spacer gasket for emi/rfi shielding lcd module and preparation thereof - Google Patents

Abstract

The present invention relates to a spacer gasket for an electromagnetic interference (EMI) / radio frequency interference (RFI) shield liquid crystal display (LCD) module and a method for manufacturing the same. The polymer elastomer sheet is cast laminated on one side of the base film, the conductive material layer is laminated on the other side of the base film, and then a through hole is formed to penetrate the upper and lower portions of the resulting laminate sheet, and the lamination The spacer gasket sheet manufactured by coating a conductive paint layer on the upper elastic sheet surface of the sieve sheet and the inner wall of the perforation is a simple manufacturing process, and the desired upper and lower surfaces of the high-density elastic body are not damaged without damaging the high impact absorption and vibration blocking properties. By maximizing both conductivity and vertical conductivity at the same time, shock absorption and vibration protection, EMI / RFI shielding and Its excellent sealability at the same time makes it very useful for the manufacture of EMI and RFI shielding gaskets for electronic communication devices.

Description

Spacer gasket for EMG / RFI shielded LC module and its manufacturing method {SPACER GASKET FOR EMI / RFI SHIELDING LCD MODULE AND PREPARATION THEREOF}             

1 is a perspective view of a conventional frame pattern spacer gasket inserted into an LCD module,

2 is a view showing a conventional spacer gasket structure wrapped with a fabric,

3 is a view showing the structure of a spacer gasket according to the present invention,

4A and 4B show a structure in which the perforations are arranged at 45 ° and 60 ° according to one embodiment of the invention,

5 is a view showing a state in which the surface of the polymer elastomer and the inner wall of the perforated gasket sheet coated with a conductive paint,

6 is a view showing a measurement specimen cut to a width of 2 mm x length 5 mm in order to measure the surface conductivity of the gasket sheet prepared according to the present invention.

* Description of reference numerals

1: gasket 10: polyurethane foam sheet

20: polyester film 30: fabric layer

40: conductive material layer 50: conductive paint layer

60: perforation

The present invention relates to a spacer gasket for an electromagnetic interference (EMI) / radio frequency interference (RFI) shielding liquid crystal device (LCD) module and a method of manufacturing the same.

As cellular mobile phones, personal digital assistants (PDAs), navigation systems (Navigation Systems), etc. are required to be miniaturized and freely mobile, they prevent dust or moisture from entering inside the LCD module, a key component of these communication devices, In order to prevent shock and vibration of the module caused by collision, shock and dropping while carrying or transporting, a slow recovery microcellular polyurethane foam 20 having high shock and vibration absorption is shown in FIG. 1. As shown schematically, a sheet cast cast (laminated) on the polyester film 20 is used by die cutting to a required size and shape. The cast laminate is die-cut into a frame pattern having a narrow width of about 1.5-5 mm on one side, and is a flexible polyurethane foam sheet of 0.15-1 mm thickness for easy handling and dimensional safety. I'm using.

However, the screen of LCD module used in these electronic communication devices is enlarged and its functions such as image and text communication and digital camera are diversified, so that the IC and LCD module used are more sensitive to static electricity, electromagnetic waves or electromagnetic waves from inside and outside the communication devices. As it reacts, the shock absorbing gaskets used in communication devices have to function simultaneously to shield EMI / RFI occurring inside and outside the device while being completely in contact with a small space without gaps.

The gasket for preventing shock and vibration is composed of an electrical insulator such as polyurethane or PET (polyethylene terephthalate) resin, and in order to simultaneously perform the EMI / RFI shielding function, upper and lower surfaces of the gasket sheet are electrically conductive. At the same time, it is necessary to have a structure of volume conductivity freely in the vertical direction of the gasket sheet, and is usually point to point measured using a specimen having a width of 2 mm and a length of 50 mm. It is desirable that the surface resistance not exceed 2 ohm.

In order to shield the interference of electromagnetic waves or electromagnetic waves generated in and out of the devices of the electronic communication devices, for example, as shown in FIG. 2, a flexible conductive material 30 such as gold, silver, copper, nickel, aluminum, or the like may be used. By wrapping the front and bottom of the flexible polyurethane foam sheet 10 with an adhesive on the top and bottom, or by adhesive molding by injecting the polyurethane foam individually or continuously into a mold containing a conductive fabric, and die-cut to the required size and shape The method of use is known (see US Pat. No. 4,857,668, 5,028,739 5,045,635 6,121,545, etc.), but the gaskets produced by these methods are shock resistant because the conductive fabrics are rigid, stretchy and non-adhesive on both sides of the polyurethane foam. There is a problem of inhibiting absorbency and vibration blocking property.

In addition, an EMI shielding gasket is disclosed in US Patent Publication No. 2003-621180 which adopts a perforated structure to improve conductivity and then coated the inside and the top thereof with a conductive paint containing conventional metals (gold, silver, copper, nickel, etc.). In this case, however, reinforcement members are used on the upper and lower surfaces of the elastomeric material, which is the basic material of the gasket, thereby impairing the shock and vibration absorbency of the foam sheet itself, and Due to the fine dust, it may interfere with the power supply of the LCD module and the PCB IC, and when processing thinly into a frame pattern, there is a lack of adhesion between the dense gap and the non-uniform LCD module ground plane, and the conductive paint contains a non-conductive resin component. The conventional conductive paint coating alone does not significantly improve conductivity, which is commonly required for EMI / RFI shielding in LCD modules in telecommunications equipment. It does not satisfy the surface resistance of 2 ohm or less in the thin sheet of width 2mm and length 50mm which are conditions.

Accordingly, it is an object of the present invention to provide a spacer gasket for an EMI / RFI shielded LCD module that can satisfy all of the various conditions.

In particular, it is an object of the present invention to maximize the desired upper and lower surface conductivity and the vertical conductivity at the same time without damaging the high shock absorbency and vibration shielding properties of the high density elastic body, so that the shock absorbing and vibration blocking, EMI / RFI with a single sealing gasket An ultra-precision hermetic gasket sheet having both shielding and good conformity is produced in a simple manufacturing process.

In order to achieve the above object, the present invention provides a polyester base film, a polymer elastomer sheet laminated on one side of the base film, and a conductive material layer such as a conductive metal or nonwoven fabric or fabric laminated on the other side of the base film. Laminate sheet containing; A through hole penetrating the upper and lower portions of the laminate sheet; And a conductive paint layer coated on an upper surface of the upper elastic sheet of the laminate sheet and an inner wall of the perforation, electromagnetic interference (EMI) and radio frequency interference (RFI) shielding gasket sheets of an electronic communication device. To provide.

Further, in the present invention, a polymer elastomer sheet is cast laminated on one side of the polyester base film, and a conductive material layer such as a conductive metal or nonwoven fabric or fabric is laminated on the other side of the base film, and then Forming a through hole to penetrate the upper and lower portions, and a method of manufacturing an EMI and RFI shielding gasket sheet of an electronic communication device comprising coating a conductive paint layer on the upper surface of the elastic sheet of the laminate sheet and the inner wall of the perforation. To provide.

Hereinafter, the present invention will be described in more detail.

The present invention introduces a metal film or foil, or a highly conductive nonwoven or fabric into the conductive material layer to increase the conductivity of the gasket on the other side of the base film relative to a laminate of a conventional polyester base film and a polymer elastomer sheet. An additional conductive through hole and surface conductive layer is introduced into the laminate to provide a shock absorbing and EMI / RFI shielding gasket sheet that exhibits sufficient conductivity even with a thin conductive coating layer.

Hereinafter, the present invention will be described in detail with reference to FIG. 3.

(1) Preparation of Polymer Elastomer Sheet / Polyester Film / Conductive Material Laminate

Among the various polyesters, PET (polyethylene terephthalate) may be most preferably used as the polyester film 20 used in the present invention, and the thickness is typically in the range of 0.02-0.15 mm.

The polymer elastomer sheet 10 used in the present invention may be used without limitation as long as the polymer elastomer sheet 10 is made of an elastic polymer material and provided with shock absorbing properties and vibration blocking properties. Foams of polymer synthetic resins such as polyurethane, polyvinyl chloride (PVC), silicone resin, ethylene vinyl acetate copolymer, polyethylene, etc .; Natural or synthetic rubbers such as natural rubber (NR), styrene butadiene rubber (SBR), ethylene propylene diene rubber (EPDM), nitrile butadiene rubber (NBR), and neoprene rubber; And other sponge or foam sheets.

 The polymer elastomer sheet may be laminated on a polyester film by cast lamination. Low compressive strain below 5%, obtained by casting a slow resilient microcellular polyurethane foam sheet known in the art, for example, to a thickness of 0.15 mm-1 mm on a 0.02 mm-0.15 mm PET film A compression set (ASTM 3574) and a slow elastic recovery force can be preferably used because it facilitates die cutting of fine frame pattern gaskets that impart shock and vibration absorption for LCD modules and has excellent dimensional stability.

Slow resilient viscoelastic polyurethane foams that impart shock absorbing and vibration barrier properties to polyurethane foams can be prepared according to known methods (US Pat. Nos. 6,391,935; 6,093,468; 6,051,622; 4,987,156; 5,420,170; 4,987,156; 4,980,386; 4,950,695; 4,839,397 and 4,367,259).

In the present invention, the polymer elastomer sheet is foamed to have a fine bubble of 90 microns or less, and is low density and flexible, and has excellent adhesion and conformability, good impact resistance, and vibration resistance. Polytech Co., Ltd.) can be used preferably. The product thickness is formed as a microscopic structure in which a very thin and flexible, and a specific gravity of 0.20g-0.50 g / cm ³ within, the cell size of the micro-cell foam of 90 microns to 0.15 mm-1 mm, and 0.20g / Excellent adhesion even under the low density of cm ³ and the compressive strength is 5% or less, compressibility up to 50% of the thickness is advantageous because it can be completely in close contact even in the uneven upper and lower planes.

In addition, the present invention satisfies the condition that the surface resistance of a sheet having a width of 2 mm and a length of 50 mm, which is usually required for an EMI / RFI shielding gasket for a conventional LCD module, should be 2 kW or less, and at the same time, necessary in the x, y, and z axis directions. In order to maximize three-dimensional conductivity, the conductive material layer 40, such as a conductive metal film or foil, or a conductive nonwoven fabric or fabric, is laminated to the opposite side of the polymer elastomer sheet of the polyester base film. It is done.

The metal film or foil is preferably a metal material having a high conductivity, such as aluminum or copper, inexpensive and flexible, and the conductive nonwoven fabric or fabric is bonded to the metal containing fibers (yarn) having excellent conductivity using a resin It can be prepared by bonding or weaving. The conductive nonwoven or woven fabric used in accordance with the present invention is present in the lower part of the gasket through the adhesive means and thus does not affect the vibration blocking and the shock absorbing ability of the gasket.

The conductive material layer preferably has a thickness of 0.2 mil or more and within 1 mil. The lamination of the conductive material layer complements the low adhesion of the conductive coating paint on the PET film to be coated later, and forms a plurality of conductive passages while reducing the amount of the overall conductive coating paint, thereby increasing the overall conductivity in the up, down, x, y, z directions. Maximize your role.

(2) formation of perforations

According to the present invention, for the sheet according to the present invention laminated as described above, known perforation method (US Pat. According to Application Publication No. 2003-62180, etc., a plurality of circular or elliptical perforations 60 are formed in the up and down direction of the gasket sheet with the perforated surface on the metal film side. The perforation may be formed by perforating with a conventionally known turret punching machine.

In this case, the perforation is preferably in the range of 0.1-1 mm in diameter, the perforation is a distance to the adjacent hole, that is, the pitch (pitch) 1-2 mm range, at an angle of 45 ° or 60 ° with the adjacent hole It is preferably arranged (see Figs. 4A and 4B). This minimizes the weakening of the strength due to perforation of the gasket sheet, and makes it easy to use by maintaining the shock and vibration absorption and dimensional safety due to the perforation of the frame module gasket for the LCD module, which has a narrow width of 1.5-5 mm. Can maximize the adhesion.

It is also desirable that the area of the entire perforated portion not exceed 20% of the total gasket sheet surface area not perforated.

(3) coating of conductive paints

Subsequently, the conductive paint 50 is coated on the polyurethane foam side and the perforated inner wall side of the perforated sheet, and dried and crosslinked to impart the required EMI / RFI shielding properties according to the conductivity of the used conductive coating (FIG. 5). Reference).

The coating methods include spray coating, knife coating, reverse roll coating, dip coating, brushing, casting, drum coating, dispensing, screen printing And well-known methods, such as impregnating, can be used.

The conductive paint is a solution in which conductive powder or flakes are dispersed in a binder resin using an aqueous medium or an organic solvent. The binder resin is an acrylic resin, a polyurethane resin, a silicone resin, a silicon fluoride resin, an epoxy resin, or a copolymer resin thereof. It may be a crosslinkable or non-crosslinkable synthetic resin that forms a flexible and soft film such as. The conductive powder or flake may be at least one selected from gold, silver, copper, nickel, aluminum, carbon, and graphite.

The conductive paint solution may have a concentration of 60% by weight or more, and the conductive powder or flake used in the conductive paint uses those having a particle diameter in the range of 0.5-50 microns, preferably in the range of 0.5-30 microns.

The physical properties and the amount of the binder resin and the thickness of the coating layer to be coated may affect the texture and adhesion of the open foam surface, wherein the conductive coating layer has a dry coating thickness of 1 mil or less, which is a slow elasticity of the elastic side of the gasket. Maintaining resilience can maximize adhesion when grounding to the LCD module.

The conductive paint used in the present invention is preferably a flexible polyurethane-based adhesive containing 60 to 80% by weight of silver flakes of 0.5-10 microns in order to maximize the conductivity of the polymer elastomer surface.

Due to the high conductivity of the metal film on one side of the foam sheet through the perforated surface by the coating, the volume conductivity of the laminate is increased by the multiple conductive passages formed by the plurality of perforated conductive passages formed with the upper and lower conductive passages and the conductive coating film. Can be maximized accordingly.

The conductivity of the gasket sheet of the present invention will be described with reference to FIG. 6, which shows a specimen for measuring electrical conductivity required for an EMI / RFI shielded LCD module spacer gasket, the conductivity of a specimen having a width of 2 mm and a length of 50 mm. Is evaluated by the surface resistance measured between the midpoint (x) of the width (between aa and bb) of one end in the longitudinal direction and the midpoint (y) of the width (between cc and dd) of the other end, without laminating a metal film. 80% of 1 mil thickness of silver flake conductive paint is only 20 때에는 for coating, drying and crosslinking the surface of the polymer elastomer, whereas according to the present invention, a metal aluminum film having a resistance of 0.05 Ω is laminated and then conductive. In the case of coating, the surface resistance value of 0.5 kPa is shown. As a result, according to the present invention, it can be seen that the electroconductive passage is formed in the lower highly conductive aluminum foil metal layer through the upper and lower conductive passages of the conductive paint coated in the perforated as well as the conductive passage of the conductive paint coated in the polymer elastomer. have.

As such, according to the present invention, the surface resistance of a specimen of width 2 mm, length 50 mm, which is a conductive use requirement of the frame pattern gasket, is formed by the formation of a highly conductive passage through the perforations by means of additional metal film lamination on the coating and the PET film. Can be kept low enough to be less than 2 dB.

Since the frame pattern gasket according to the present invention formed as described above is excellent in conductivity, it is simply acrylic or polyurethane based aqueous or organic on the surface of the conductive material layer without using a conventional expensive conductive adhesive tape when assembling the LCD module. Solvent pressure sensitive adhesives may be coated with a dry film thickness of 0.005-0.01 mm by a method such as a doctor knife or roll coating and then adhesively inserted. As such, the gasket according to the present invention obtains high grounding conductivity due to the high conductivity of the conductive material layer when adhered to the conductive ground plane of the LCD module, thereby simplifying the process and using an economical conductive transfer adhesive tape. Enable adhesive grounding. In general, when using a compact spacer gasket in a narrow space such as an LCD module of a cellular phone, PDA, navigation system, etc., a PET film laminated shock and vibration resistant foam sheet is die-cut into a gasket of the required size and shape. Known adhesive tape is additionally laminated to the PET film side before it is bonded to the LCD module to be assembled and fixed on one side, and the open flexible foam side is assembled without using an adhesive. According to the present invention, however, the pressure-sensitive adhesive is coated on the surface of the metal film, dried and then masked with a release paper such as PET film or kraft paper, and die-cut into a gasket having the required shape. Can be used for module assembly.

The gasket sheet according to the present invention can be usefully used in various electronic communication devices such as televisions, radios, computers, medical devices, office devices or communication devices.

Preferred Embodiment

According to a preferred embodiment of the present invention, the gasket sheet can be prepared as follows:

First, the polyurethane foam sheet is cast laminated on the PET film to a thickness of 0.15-1 mm. At this time, the polyurethane foam sheet is formed of a very fine bubble of less than 90 microns and formed with a soft foam surface layer of 0.5 g / cm ³ specific gravity, so as to closely adhere to the complex and uneven ground surface.

Subsequently, a 10-20 micron thick metal film or foil is laminated to the PET side of the laminated polyurethane / PET laminate and the resulting laminate is then perforated. The diameter of the perforations produced during drilling is in the range of 0.1-1 mm, the arrangement of perforated holes is at an angle of 45 ° or 60 °, and the distance (pitch) between the holes is between 1.0-2 mm, and the total area of the holes Is within 20% of the gasket sheet surface area prior to perforation to maintain the strength of the closed gasket and maintain its function.

In order to retain the high conductivity and adhesion of the laminated sheet thus obtained and the inherent slow elastic recovery, impact and vibration absorption of the polyurethane, a conductive coating layer is then coated on the polyurethane foam surface and the perforated inner wall thereon. do. The conductive coating layer is coated to a dry thickness of 1 mil or less using a conductive paint containing 60 wt% or more of silver flakes of 0.5-30 microns in size so as to be soft and flexible and have excellent adhesion.

The gasket sheet according to the present invention manufactured as described above has a surface resistivity of 0.05 kPa or less, and even when repeated use, surface cracking does not occur due to bending compression, etc. Elastic recovery property is preserved, good adhesion and high EMI / RFI shielding property.

When the gasket sheet is used as a frame pattern sealing gasket for assembling the LCD module, the width of one surface is die cut in a range of 1.5-5 mm and inserted by a pressure-sensitive adhesive.

According to the present invention, after laminating a conductive material on the surface of the base film on the laminate of the polyester base film and the polymer elastomer sheet, the resulting laminate sheet is perforated to form perforations, and the upper elastic sheet side of the laminate sheet and The spacer gasket sheet manufactured by coating the conductive paint layer on the inner wall of the perforation is maximized by simultaneously maximizing the desired upper and lower surface conductivity and vertical conductivity without compromising the high shock absorbency and vibration blocking property of the high density elastic body in a simple manufacturing process. The combination of shock absorption and vibration blocking, EMI / RFI shielding and excellent sealing properties is very useful for the manufacture of electromagnetic interference (EMI) and radiofrequency interference (RFI) shielding gaskets in electronic communication devices.

Claims (15)

A laminate sheet comprising a polyester film, a polymer elastomer sheet laminated on one side of the film, and a conductive material layer laminated on the other side of the film; A through hole penetrating the upper and lower parts of the laminate sheet; And A conductive paint layer coated on the elastic sheet upper surface of the laminate sheet and the inner wall of the perforation Electromagnetic interference (EMI) and radiofrequency interference (RFI) shielding gasket sheet comprising a. 2. The gasket sheet of claim 1, wherein the layer of conductive material consists of a metal film or foil, or a conductive nonwoven or fabric. The gasket sheet according to claim 1, wherein the polymer elastomer sheet is made of a synthetic resin foam or rubber. The gasket sheet according to claim 1, wherein the polyester film has a thickness in the range of 0.02-0.15 mm and the polymer elastomer sheet has a thickness in the range of 0.15-1 mm. 2. The gasket sheet of claim 1, wherein the layer of conductive material has a thickness in the range of 0.2-1 mil. The gasket sheet according to claim 1, wherein the perforation has a diameter in the range of 0.1-1 mm. 7. The gasket sheet according to claim 6, wherein the perforations are in a range of 1-2 mm from the adjacent perforations and are arranged at an angle of 45 ° or 60 ° with the adjacent perforations. 7. The gasket sheet according to claim 6, wherein the perforation is within a range of 1-2 mm from adjacent perforations and the area occupied by the entire perforation is within 20% of the gasket sheet surface area. The gasket sheet according to claim 1, wherein the conductive paint layer has a composition in which conductive powder or flakes are dispersed in a binder resin. The gasket sheet according to claim 1, wherein the conductive paint layer has a dry thickness of 1 mil or less. 2. The gasket sheet according to claim 1, wherein the specimen has a width of 2 mm and a length of 50 mm, indicating a surface resistance of 2 ohm or less when measuring surface resistance. Cast lamination of the polymer elastomer sheet on one side of the polyester film, Laminating a conductive material layer on the other side of the polyester film, Through holes are formed to penetrate the upper and lower portions of the resulting laminate sheet, A method of manufacturing an EMI and RFI shielding gasket sheet, comprising coating a conductive paint layer on the elastic sheet upper surface of the laminate sheet and the inner wall of the perforation. 13. The method of claim 12, wherein the layer of conductive material consists of a metal film or foil, or a conductive nonwoven or fabric. The method according to claim 12, wherein the conductive paint layer is formed by applying a coating solution in which conductive powder or flakes are dispersed in a binder resin at a concentration of 60% by weight or more and then dry crosslinking. An electronic communication device comprising a spacer gasket obtained by die casting a gasket sheet according to any one of claims 1 to 11.

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