WO2009025518A2

WO2009025518A2 - Electrically conductive adhesive tape and method for preparing the same

Info

Publication number: WO2009025518A2
Application number: PCT/KR2008/004903
Authority: WO
Inventors: Jin-Ho Song
Original assignee: Nano Interface Technology
Priority date: 2007-08-22
Filing date: 2008-08-22
Publication date: 2009-02-26
Also published as: TW200914574A; WO2009025518A3; KR100825675B1

Abstract

Disclosed is an electrically conductive adhesive tape including: a mesh type elastic support layer having open spaces; an electrically conductive layer laminated one surface of the mesh type elastic support layer; and a conductive adhesive layer disposed on other surface of the mesh type elastic support layer, and a method of preparing the same. In the disclosed adhesive tape including the mesh type elastic support layer having an electrically conductive layer laminated on one surface thereof, and a conductive adhesive layer disposed on the other surface thereof can be used to shield or absorb an electromagnetic wave occurring from an electronic device because through open spaces of the mesh type elastic support layer, the electrically conductive layer comes in contact with the conductive adhesive layer, thereby electrically connecting one surface of the adhesive tape to the other surface.

Description

ELECTRICALLY CONDUCTIVE ADHESIVE TAPE AND METHOD FOR

PREPARING THE SAME

Technical Field The present invention relates to an electrically conductive adhesive tape which can be used for absorbing or shielding an electromagnetic wave and a method of preparing the same.

Background Art

The use of various kinds of electronic communication devices has rapidly increased with the development of technology. Such modern facilities provide great convenience to human life, but at the same time cause an adverse effect. For example, all sorts of harmful electromagnetic waves occurring from electronic communication devices cause problems in peripheral electronic communication devices or components, such as malfunction, performance degradation, noise, image deterioration, lifetime reduction, quality deterioration, etc.

In order to shield an electromagnetic wave causing such problems, various electromagnetic wave shielding materials have been recently developed. For example, there was an electromagnetic wave shielding tape obtained by applying an electrically conductive pressure sensitive adhesive to a metal foil made of gold, silver, aluminum, nickel, tin, etc. However, in preparing such an electromagnetic wave shielding tape or applying the electromagnetic wave shielding tape to an electronic device, it is difficult to process the tape due to irregular minute creases occurring on a tape surface. Also, since flexibility or elasticity is insufficient due to low elongation of metal, a compressed electromagnetic wave shielding tape cannot be restored to its original state. Thus, there is a limitation in the use range of the electromagnetic wave shielding tape.

In order to solve such problems, another electromagnetic wave shielding tape was developed, in which the electromagnetic wave shielding tape was prepared by forming a metal film made of gold, silver, aluminum, nickel, tin, etc. on the surface of a conductive fabric or a non-woven fabric by using electroplating, or electroless plating, etc. and applying a hot-melt adhesive or a pressure sensitive adhesive . However, the above mentioned electromagnetic wave shielding tape including a metal film formed on the surface of a conductive fabric, etc. has a surface resistance (an average of 0.04 ohm/sq) higher than that (an average of about 0.01 ohm/sq) of an electromagnetic wave shielding tape using only a metal foil, and thus has low electromagnetic wave shielding efficiency.

Also, in the case of the electromagnetic wave shielding tape including the conductive fabric, etc., there is a problem in that an electromagnetic wave shielding effect is reduced due to low electric conductivity and rapid oxidation under high temperature and high moisture. Moreover, there is a problem in that minute spaces between yarns used for the fabric, and minute spaces between fibers included in the yarn increase resistance, thereby reducing the electromagnetic wave shielding property. Also, dust or moisture absorbed in the minute spaces may operate as an element interfering with electromagnetic wave shielding, and thus it may be impossible to effectively shield an electromagnetic wave, thereby causing malfunction of an electronic device.

Furthermore, when such an electromagnetic wave shielding tape is used as a gasket, a minute conductive fibrous tissue may be separated from the tape during a cutting process, and may pollute an IC chip, etc. , thereby reducing performance of an electronic device.

Disclosure

Technical Problem

In order to solve the above described problems, the inventors of the present invention have tried to develop a high-quality electromagnetic wave shielding material which can be used for a small-sized precision electronic device, the material having a thinner thickness and yet a high electromagnetic wave shielding/absorbing property and high flexibility. Accordingly, the inventors found that it is possible to effectively shield or absorb an electromagnetic wave by using an adhesive tape including a screen mesh fabric, the screen mesh fabric having an electrically conductive material (capable of shielding or absorbing an electromagnetic wave) laminated on one surface thereof, and a conductive adhesive applied on the other surface thereof, because through mesh portions of the screen mesh fabric, the applied conductive adhesive comes in contact with the electrically conductive material, thereby electrically connecting one surface of the adhesive tape to the other surface.

The present invention is based on this finding. Technical solution

In accordance with an aspect of the present invention, there is provided an electrically conductive adhesive tape including: a mesh type elastic support layer having open spaces; an electrically conductive layer laminated one surface of the mesh type elastic support layer; and a conductive adhesive layer disposed on other surface of the mesh type elastic support layer.

In accordance with another aspect of the present invention, there is provided a method of preparing an electrically conductive adhesive tape, the method including the steps of: forming a mesh type elastic support layer having open spaces; laminating an electrically conductive layer on one surface of the mesh type elastic support layer; and forming a conductive adhesive layer by applying a conductive adhesive on another surface of the mesh type elastic support layer.

Brief Description of the Drawings FIG. 1 is a cross-sectional view of an electrically conductive adhesive tape according to an embodiment of the present invention.

FIG. 2 is a perspective view of the electrically conductive adhesive tape according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of an electrically conductive adhesive tape according to another embodiment of the present invention.

FIG. 4 is a perspective view of the electrically conductive adhesive tape according to another embodiment of the present invention.

FIG. 5 is a conceptual view illustrating a process of preparing an electrically conductive adhesive tape according to an embodiment of the present invention.

FIG. 6 is a conceptual view illustrating a process of preparing an electrically conductive adhesive tape according to another embodiment of the present invention.

1: mesh type elastic support layer,

2: electrically conductive layer,

3: conductive adhesive layer, 4: embossed portion,

101: winding roller for mesh type elastic support layer,

102: winding roller for mesh type elastic support layer, 201: upper heat-pressing roller,

202: lower heat-pressing roller,

301: spray device for application,

401: rubber roller,

402: embossing roller

Best Mode

Mode for Invention

Hereinafter, the present invention will be described in detail.

In the present invention, the term "open space" refers to an empty space upwardly/downwardly penetrated over an entire surface, such as a mesh of a mesh type fabric, or a through hole of an elastic polymer sheet, etc.

FIG. 1 shows an example of an electromagnetic wave shielding sheet according to an embodiment of the present invention. In an electrically conductive adhesive tape as shown in FIG. 1, a mesh type elastic support layer 1 has an electrically conductive layer 2 laminated on one surface thereof and a conductive adhesive layer 3 disposed on the other surface of thereof.

In the electrically conductive adhesive tape according to the present invention, the conductive adhesive layer 3 comes in contact with the electrically conductive layer 2 through open spaces of the mesh type elastic support layer 1, thereby electrically connecting one surface of the adhesive tape to the other surface. Accordingly, the electrically conductive adhesive tape according to the present invention can shield or absorb an electromagnetic wave occurring from an electronic device.

The electrically conductive adhesive tape according to the present invention includes a mesh type elastic support layer 1 capable of protecting an electronic device from impact or vibration. As the mesh type elastic support layer 1, a mesh type fabric may be used. There is no limitation in the mesh type fabric that may be used in the present invention, as long as the mesh type fabric is a loosely weaved fabric obtained by using yarn, like a net, that is, a weaved fabric obtained by crossing warp and weft yarns with a predetermined interval in which meshes are formed. Examples of the yarn include: spun yarn obtained by twisting natural fibers such as cotton, wool, hemp, etc.; filament yarn made of natural fibers such as silk; and mono filament yarn or multi-filament yarn, which is obtained by twisting synthetic fibers such as nylon, polyethylene, polyester, polyurethane, etc. According to an embodiment of the present invention, as the mesh type elastic support layer, a mesh type fabric that is weaved by crossing polyester filament yarns in both warp and weft directions is used.

Such a mesh type fabric has meshes formed therein, and herein, there is no particular limitation in the rate of such meshes. However, according to an embodiment of the present invention, it is preferable that the meshes are formed at a ratio of about 10 to 100 mesh per lciif. Accordingly, the elastic support layer 1 may include open spaces of about 10 to 80% with respect to the entire surface, and through such open spaces, the conductive adhesive layer 3 comes in contact with the electrically conductive layer 2, thereby electrically connecting one surface of the adhesive tape to the other surface.

In addition to the mesh type fabric, as the mesh type elastic support layer 1, a polymer sheet having through holes formed therein with a predetermined interval may be used. There is no limitation in the polymer sheet that may be used in the present invention, as long as the polymer sheet is made of an elastic material capable of protecting an electronic device from impact or vibration. Examples of the polymer sheet include a polyethylene-based resin, a polypropylene- based resin, a polyvinyl chloride-based resin, a polyvinylidene chloride-based resin, a polystyrene-based resin, a polyester-based resin, a polyacrylic resin, a styrene-acrylonitrile (SAN) copolymer, an ethylene-vinyl alcohol copolymer (EVA resin) , an acrylonitrile- butadiene-styrene (ABS) resin, a polyurethane-based resin, a fluoro resin, a silicon-based resin, etc., but the present invention is not limited thereto.

The polymer sheet made of the above mentioned polymer resin may include open spaces by formation of through holes with a predetermined interval. It is preferable that the through holes are formed at a ratio of about 1 to 100 holes per lcuf in such a manner that the polymer sheet made of the polymer resin includes open spaces of about 10 to 80% with respect to the entire surface. Also, the diameter of each through hole is not particularly limited, but is preferably within a range of about 0.1 to 5mπi . Each through hole and its adjacent through holes form an angle of about 30 to 90°. The through holes generally have a circular shape, a triangular shape, or a square shape, etc, without particular limitation.

The thickness of the mesh type elastic support layer may be adjusted according to a portion where an adhesive tape is applied so as to protect an electronic device or an electronic component from impact or vibration. For example, in a large size electronic device such as a notebook computer, a relatively thick elastic support layer is preferably used, and in a small size electronic device such as a cellular phone, a thin elastic support layer is preferably used. According to an embodiment of the present invention, the thickness of the mesh type elastic support layer 1 may be about 0.05 to 5mm.

On one surface of such a mesh type elastic support layer 1, an electrically conductive layer 2 is laminated. As the electrically conductive layer, a metal film made of a metal material capable of shielding or absorbing an electromagnetic wave occurring from an electronic device may be used, and preferably, a metal foil may be used. Unlike a conventional electromagnetic wave shielding tape employing a conductive fabric, the adhesive tape of the present invention, the tape using such a metal film as an electrically conductive layer, even when cut, is not subjected to contamination by a metal particle or a fibrous tissue. Also, the electrically conductive layer has a surface resistance of about 0.01 ohm/sq, which is lower than that (about 0.04 ohm/sq) of a conventional conductive fabric used for a conventional electromagnetic wave shielding tape. In other words, the electrically conductive layer has high surface electrical conductivity. Thus, the adhesive tape according to the present invention may have a high electromagnetic wave shielding/absorbing property.

Non-limiting examples of the metal material include gold, platinum, silver, copper, aluminum, tin, nickel, and an alloy thereof. According to an embodiment of the present invention, as the electrically conductive layer, a metal foil made of aluminum may be used.

The thickness of the electrically conductive layer may be easily adjusted by a person skilled in the art as required. According to an embodiment of the present invention, the thickness of the electrically conductive layer is within a range of about 2 to 300μm, preferably of about 3 to lOOμm, and more preferably of about 5 to 50 μm. On the other surface of the mesh type elastic support layer including the electrically conductive layer laminated thereon as described above, a conductive adhesive layer 3 is disposed. The conductive adhesive layer 3 may be formed by applying a conductive adhesive on the other surface of the mesh type elastic support layer 1.

The conductive adhesive is not particularly limited as long as the conductive adhesive is known in the art. In general, the conductive adhesive includes an adhesive polymer resin, conductive filler, and other filler. The conductive filler is uniformly dispersed within the adhesive polymer resin, and thus conductive filler particles may be connected to each other thereby forming a continuous path. Since electrons can be passed through such a continuous path, one surface of the adhesive tape of the present invention may be electrically connected to the other surface when the conductive adhesive layer comes in contact with the electrically conductive layer through open spaces of the mesh type elastic support layer.

Examples of an adhesive polymer resin that may be used for the conductive adhesive may include, but are not limited to, an epoxy resin, a polyester resin, an acrylic resin, a polyimide resin, polysulfone, a phenolic resin, a melamine resin, etc.

As the conductive filler, gold, platinum, silver, copper, aluminum, tin, nickel, carbon black, carbon fiber, graphite, polyacetylene, polyaniline, polypyrrole, polythiophene, polysulfurnitride, poly-p- phenylene, polyphenylenesulfide, poly-p- phenylenevinylene, and a mixture thereof may be used, but the present invention is not limited thereto. Such conductive filler may be included in an amount of about

10 to 200 parts by weight based on 100 parts by weight of the adhesive polymer resin.

The thickness of the conductive adhesive layer 3 is not particularly limited, but is preferably within a range of about 5 to 50μm. If the thickness of the conductive adhesive layer is less than 5μm, adhesive strength of an adhesive tape may be reduced. If the thickness of the conductive adhesive layer is greater than 50μm, conductivity may be reduced, and also, it may be difficult to apply the conductive adhesive layer in an electronic device having densely disposed components.

Also, on the surface of the electrically conductive adhesive tape according to the present invention, embossed portions 4 may be formed in respective open spaces of the mesh type elastic support layer 1 (see FIGs. 3 and 4) . Compared to an electromagnetic wave shielding adhesive tape with no embossed portion, a conductive adhesive tape having such embossed portions 4 formed on the surface thereof have improved processibility due to reduction of irregular creases. Further, even when an electronic device has an uneven surface, that is, a rough surface, the electrically conductive adhesive tape according to the present invention may have an improved adhesion property with the electronic device due to the embossed portions.

Also, the shape and depth of the embossed portions 4 may be variously adjusted according to a case where the adhesive tape is required. The shape of the embossed portions may include a concave hemisphere shape, a concave quadrangle, etc. without particular limitation. According to an embodiment of the present invention, when a mesh type fabric is used as the mesh type elastic support layer, the shape of the embossed portions is preferably a concave quadrangle. Also, the depth of the embossed portions may correspond to the thickness of the mesh type elastic support layer, for example, about less than 5mm, but is not particularly limited thereto as long as the embossed portions are seen.

Meanwhile, the present invention provides a method of preparing the electrically conductive adhesive tape.

According to an embodiment of the present invention, the electrically conductive adhesive tape may be prepared by the steps of: forming a mesh type elastic support layer; laminating an electrically conductive layer on one surface of the mesh type elastic support layer; and forming a conductive adhesive layer by applying a conductive adhesive on the other surface of the mesh type elastic support layer.

For example, a mesh type elastic support layer is formed by using a mesh type fabric weaved by a conventional method known in the art, and then on one surface of the mesh type elastic support layer, an electrically conductive layer made of a metal material is laminated. Herein, an adhesive means, such as a conductive or non-conductive hot-melt adhesive, or a pressure sensitive adhesive, may be used to easily laminate the mesh type elastic support layer with the electrically conductive layer. Then, a conductive adhesive layer is disposed by applying a conductive adhesive on the other surface of the mesh type elastic support layer, and thereby an electrically conductive adhesive tape may be obtained.

Otherwise, a mesh type elastic support layer is prepared by disposing a conductive or non-conductive hot-melt adhesive on a polymer sheet prepared by a conventional method known in the art, and forming through holes with a predetermined interval by using a punching machine. Then, a preliminarily prepared electrically conductive layer is laminated on the prepared mesh type elastic support layer. Herein, when heat is added to the mesh type elastic support layer, the hot-melt adhesive disposed on the surface of the mesh type elastic support layer is melted, thereby facilitating the lamination of the mesh type elastic support layer with the electrically conductive layer. Then, a conductive adhesive layer is disposed by applying a conductive adhesive on the other surface of the mesh type elastic support layer, and thereby an electrically conductive adhesive tape may be obtained.

As a more specific example, as shown in FIG. 5, in a winding roller 101, a mesh type fabric is rolled up, the mesh type fabric being weaved by uniformly crossing polyethylene filament yarns in both warp and weft directions so that a mesh can be formed, and in another winding roller 102, a prepared aluminum foil is rolled up. Then, when the mesh type fabric 1 and the aluminum foil 2 fed from the winding rollers 101 and 102 pass through between an upper heat-pressing roller 201 and a lower heat-pressing roller 202, the aluminum foil 2 is laminated on one surface of the mesh type fabric 1. Herein, if an adhesive means, such as a conductive or non-conductive hot-melt adhesive, is disposed on the surface of the mesh type fabric 1, it is possible to easily laminate the mesh type fabric 1 with the aluminum foil 2 by heating.

After the laminating process, on the other surface of the mesh type fabric 1, a conductive adhesive is applied from a spray device for application 301, thereby forming a conductive adhesive layer 3. Herein, since the conductive adhesive is also applied to meshes of the mesh type fabric, the conductive adhesive layer can come in contact with the aluminum foil, thereby electrically connecting one surface of the adhesive tape to the other surface. Accordingly, an electrically conductive adhesive tape capable of shielding or absorbing an electromagnetic wave may be obtained.

Also, the preparation method according to the present invention may further include, after the step of forming the conductive adhesive layer, a step of forming embossed portions in respective open spaces of the mesh type elastic support layer by using an embossing roller (see FIG. 6) .

The embossed portions 4 may be formed by a roller device including an embossing roller 402 having embossed portions formed on the surface thereof, and a rubber roller 401 having a flat surface. Specifically, the embossed portions 4 on the surface of the adhesive tape may be formed by using a conventional roller device known in the art, such as the embossing roller 402 having embossed portions formed on the surface thereof.

For example, the embossed portions 4 can be easily formed by using a roller device including a rubber roller 401 with a flat outer circumferential surface and an embossing roller 402 having various convex-shaped embossed portions formed on the outer circumferential surface thereof, the embossing roller 402 rotating while contacting the rubber roller. When the rubber roller 401 and the embossing roller 402 are driven, the adhesive tape including the mesh type elastic support layer 1 having an electrically conductive layer 2 laminated on one surface thereof and a conductive adhesive layer 3 laminated on the other surface thereof is passed through between the rubber roller 401 and the embossing roller 402, and herein, on the contact portion where the embossed portions of the embossing roller 402 and the rubber of the rubber roller 401 are contact with each other, pressure of the embossing roller and elasticity of the rubber roller form the embossed portions 4 on the surface of the adhesive tape. The embossed portions 4 formed as described above can prevent the occurrence of irregular creases in the electrically conductive layer and can improve adhesion property with the adhesive tape .

Industrial Applicability

The adhesive tape according to the present invention, which includes a mesh type elastic support layer having an electrically conductive layer laminated on one surface thereof, and a conductive adhesive layer disposed on the other surface thereof, can be used to shield or absorb an electromagnetic wave occurring from an electronic device because through open spaces of the mesh type elastic support layer, the electrically conductive layer comes in contact with the conductive adhesive layer, thereby electrically connecting one surface of the adhesive tape to the other surface.

Although several exemplary embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

1. An electrically conductive adhesive tape comprising : a mesh type elastic support layer having open spaces; an electrically conductive layer laminated one surface of the mesh type elastic support layer; and a conductive adhesive layer disposed on another surface of the mesh type elastic support layer.

2. The electrically conductive adhesive tape as claimed in claim 1, wherein the conductive adhesive layer comes in contact with the electrically conductive layer through the open spaces of the mesh type elastic support layer, thereby electrically connecting one surface of the adhesive tape to another surface.

3. The electrically conductive adhesive tape as claimed in claim 1, wherein embossed portions are formed in respective open spaces of the mesh type elastic support layer.

4. The electrically conductive adhesive tape as claimed in claim 1, wherein the open spaces of the mesh type elastic support layer are within a range of about 10 to 80% with respect to an entire surface.

5. The electrically conductive adhesive tape as claimed in claim 1, wherein the mesh type elastic support layer has a thickness ranging from 0.05 to 5mm.

6. The electrically conductive adhesive tape as claimed in claim 1, wherein the mesh type elastic support layer comprises a mesh type fabric or an elastic polymer sheet having through holes formed therein with a predetermined interval.

7. The electrically conductive adhesive tape as claimed in claim β, wherein the mesh type fabric comprises meshes formed therein at a ratio of 10 to 100 per lcm².

8. The electrically conductive adhesive tape as claimed in claim 6, wherein the mesh type fabric is weaved by using cotton yarn, mono filament yarn, or multi-filament yarn.

9. The electrically conductive adhesive tape as claimed in claim 6, wherein the elastic polymer sheet is made of a material selected from the group including a polyethylene-based resin, a polypropylene-based resin, a polyvinyl chloride-based resin, a polyvinylidene chloride-based resin, a polystyrene-based resin, a polyester-based resin, a polyacrylic resin, a styrene- acrylonitrile (SAN) copolymer, an ethylene-vinyl alcohol copolymer (EVA resin), an acrylonitrile-butadiene- styrene (ABS) resin, a polyurethane-based resin, a fluoro resin, a silicon-based resin.

10. The electrically conductive adhesive tape as claimed in claim 6, wherein the through holes have a diameter ranging from 0.1 to 5mm.

11. The electrically conductive adhesive tape as claimed in claim 6, wherein the through holes are formed at a ratio of about 1 to 100 per lcm².

12. The electrically conductive adhesive tape as claimed in claim 1, wherein the electrically conductive layer has a thickness ranging from 2 to 300μm.

13. The electrically conductive adhesive tape as claimed in claim 1, wherein the electrically conductive layer is a metal film made of a material selected from the group including gold, platinum, silver, copper, aluminum, tin, nickel, and an alloy thereof.

14. The electrically conductive adhesive tape as claimed in claim 1, wherein the conductive adhesive layer comprises an adhesive polymer resin and conductive filler.

15. The electrically conductive adhesive tape as claimed in claim 14, wherein the adhesive polymer resin is selected from the group including an epoxy resin, a polyester resin, an acrylic resin, a polyimide resin, polysulfone, a phenolic resin, and a melamine resin.

16. The electrically conductive adhesive tape as claimed in claim 14, wherein the conductive filler is selected from the group including gold, platinum, silver, copper, aluminum, tin, nickel, carbon black, carbon fiber, graphite, polyacetylene, polyaniline, polypyrrole, polythiophene, polysulfurnitride, poly-p- phenylene, polyphenylenesulfide, poly-p- phenylenevinylene, and a mixture thereof.

17. The electrically conductive adhesive tape as claimed in claim 1, wherein the conductive adhesive layer has a thickness ranging from 5 to 50/ffll.

18. A method of preparing an electrically conductive adhesive tape, the method comprising the steps of: forming a mesh type elastic support layer having open spaces; laminating an electrically conductive layer on one surface of the mesh type elastic support layer; and forming a conductive adhesive layer by applying a conductive adhesive on another surface of the mesh type elastic support layer.

19. The method as claimed in claim 18, further comprising the step of forming embossed portions in respective open spaces of the mesh type elastic support layer by using an embossing roller, after the step of forming the conductive adhesive layer.