KR101884052B1 - Electromagnetic wave shielding film for flexible printed circuit board and the preparation method thereof - Google Patents
Electromagnetic wave shielding film for flexible printed circuit board and the preparation method thereof Download PDFInfo
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- KR101884052B1 KR101884052B1 KR1020150182935A KR20150182935A KR101884052B1 KR 101884052 B1 KR101884052 B1 KR 101884052B1 KR 1020150182935 A KR1020150182935 A KR 1020150182935A KR 20150182935 A KR20150182935 A KR 20150182935A KR 101884052 B1 KR101884052 B1 KR 101884052B1
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- adhesive layer
- conductive adhesive
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K9/00—Screening of apparatus or components against electric or magnetic fields
- H05K9/0073—Shielding materials
- H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
- H05K9/0083—Electromagnetic shielding materials, e.g. EMI, RFI shielding comprising electro-conductive non-fibrous particles embedded in an electrically insulating supporting structure, e.g. powder, flakes, whiskers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
- B32B7/04—Interconnection of layers
- B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B15/00—Layered products comprising a layer of metal
- B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
- B32B15/08—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
- B32B15/088—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin comprising polyamides
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/0213—Electrical arrangements not otherwise provided for
- H05K1/0216—Reduction of cross-talk, noise or electromagnetic interference
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K9/00—Screening of apparatus or components against electric or magnetic fields
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/20—Properties of the layers or laminate having particular electrical or magnetic properties, e.g. piezoelectric
- B32B2307/212—Electromagnetic interference shielding
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- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Laminated Bodies (AREA)
- Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
Abstract
The present invention relates to an electromagnetic wave shielding film comprising an insulating layer and a conductive adhesive layer and having an electromagnetic shielding ratio of 50 to 65 dB at a frequency of 1 GHz in the ASTM 4935-1 method, wherein the content of the conductive filler in the conductive adhesive layer is 60 to 80% The resistivity [rho d ] value of the conductive adhesive layer is in the range of 1.0E-04 to 3.7E-04 [Omega] cm under the condition that the thickness is 10 mu m.
In the present invention, the flame retardant used as a component of the conductive adhesive layer is not used. Instead, the shape and content of the conductive filler are controlled to increase the packing density, to lower the specific resistance, to provide excellent electromagnetic shielding performance, and to exhibit excellent conductivity, heat resistance and mechanical properties.
Description
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shielding film for shielding electromagnetic waves generated from electronic parts such as a printed circuit board used in electronic products such as a computer, a communication device, a printer, a mobile phone, and a video camera, a communication device such as a cable, And a manufacturing method thereof.
In general, there is an increasing demand for miniaturization, planarization, and high functionality of electronic devices. In order to meet these demands, complex electromagnetic noise is generated by implementing components in different frequency ranges in the same electronic device, and it is becoming difficult to take measures against such complex electromagnetic noise. On the other hand, data transmission cables are also increasingly demanding for thinner and less electromagnetic noise emissions. In the case of transmitting a large amount of data, an error occurs in the data due to the interference of the data due to electromagnetic noise, and data is frequently lost.
In order to satisfy electromagnetic compatibility, it is necessary to reduce the electromagnetic noise generated from various electric / electronic and communication devices as much as possible and to reduce the electromagnetic susceptibility to the external electromagnetic environment so as to enhance the electromagnetic wave resistance of the device itself. The most important characteristics required for electromagnetic compatibility products to be inserted into various electrical, electronic and communication devices are that electromagnetic shielding ratio and absorption rate must be large, and electromagnetic compatibility products should be small and thin according to the trend of short and light equipment.
As a countermeasure for solving the electromagnetic noise problem described above, a shielding film in which a metal layer and a conductive adhesive layer are sequentially provided on one or more insulating layers is often used. In order to increase the flame retardancy of such a shielding film, a flame retardant has been used as a component of the conductive adhesive layer. However, since the content of the conductive filler constituting the conductive adhesive layer is decreased by the amount of the flame retardant, the shielding effect of the electromagnetic shielding film is unsatisfactory .
The present inventors have devised in order to solve the above-mentioned problems. The inventor of the present invention has devised a solution to this problem by providing a conductive adhesive layer of a flame retardant non-emissive type, wherein the insulating layer is made of a polyimide (PI) film, polyimide, Meade and polyamic acid resin, it exhibits a flame retardant effect based on the flame retardancy of the polyimide itself, exhibits excellent electromagnetic shielding performance, and at the same time exhibits conductivity, heat resistance, mechanical properties and flame retardancy And to provide a novel electromagnetic wave shielding film which exhibits the above properties.
In order to achieve the above object, the present invention provides an electromagnetic shielding film comprising an insulating layer and a conductive adhesive layer, wherein the electromagnetic shielding film has an electromagnetic shielding ratio of 50 to 65 dB at a frequency of 1 GHz in ASTM 4935-1 method, The resistivity [rho d ] value of the conductive adhesive layer is in the range of 1.0E-04 to 3.7E-04? Cm under the condition that the content is 60 to 80% and the thickness is 10 mu m.
According to a preferred example of the present invention, the electromagnetic wave shielding film has a conductive filler content of 60 to 80% in the conductive adhesive layer, and the conductive adhesive layer has a thickness of 10 m after hot pressing, The resistivity [rho d ] value of the conductive adhesive layer containing two or more different conductive fillers is 1.0E-04 to 1.5E-04 Lt; / RTI > cm. The sheet resistance can also range from 100 mΩ to 150 mΩ / sq and the contact resistance can range from 0.5 to 2.2 Ω.
In the present invention, the conductive adhesive layer includes two or more conductive fillers and resins having different shapes.
In the present invention, the two or more conductive fillers having different shapes may be selected from the group consisting of spherical, flaky, dendrite, cone, pyramid and amorphous.
In the present invention, the conductive filler may be a mixture of a spherical first conductive filler and a needle-shaped second conductive filler.
In the present invention, the average particle diameter of the first conductive filler may be (d50) 2 to 2.5 占 퐉, and the average particle diameter d50 of the second conductive filler may be 7 to 9 占 퐉.
According to another preferred embodiment of the present invention, the content of the conductive filler may be 60 to 80 parts by weight, preferably 65 to 77 parts by weight, based on 100 parts by weight of the conductive adhesive layer. In this case, the content ratio of the first conductive filler and the second conductive filler may be 15 to 60:70 to 80 by weight based on the weight of each composition.
According to another preferred embodiment of the present invention, the conductive adhesive layer includes a first conductive adhesive layer and a second conductive adhesive layer respectively located on the upper and lower surfaces with respect to a thickness direction; And an intermediate layer disposed therebetween, wherein the first conductive adhesive layer, the intermediate layer, and the second conductive adhesive layer may have different compositions of the first conductive filler and the second conductive filler having different shapes from each other.
In the present invention, the first conductive filler and the second conductive filler may be located in the first conductive adhesive layer and the second conductive adhesive layer, respectively, and the first conductive filler and the second conductive filler may be mixed in the intermediate layer .
In the present invention, the conductive adhesive layer may have a packing density increasing from the both surfaces toward the intermediate layer with respect to the thickness direction.
In the present invention, the conductive adhesive layer may have a value of adhesive force of 1.0 kgf / cm or more with the coverlay in the C-stage state.
In the present invention, the insulating layer, the conductive adhesive layer, or both may be non-flammable type.
In the present invention, the resin constituting the insulating layer and the conductive adhesive layer may be a thermosetting resin, and the insulating layer may be formed of a polyimide (PI) film or a polyimide, a polyamide, a polyamideimide and a polyamic acid resin Or a thermoplastic polyimide layer formed by applying a liquid composition onto a base film and then curing the resin composition containing at least one selected.
In the present invention, the insulating layer may further include 3 to 30 parts by weight of electrically nonconductive organic or inorganic filler based on 100 parts by weight of the insulating layer.
According to a preferred embodiment of the present invention, each of the insulating layer and the conductive adhesive layer may further include a release film.
In addition, the present invention relates to a substrate comprising at least one circuit pattern; And an electromagnetic wave shielding type flexible printed circuit board (FPCB) comprising the electromagnetic wave shielding film disposed on one side or both sides of the substrate.
The novel electromagnetic wave shielding film according to the present invention can increase the amount of the conductive material used instead of the flame retardant used as a component of the conventional conductive adhesive layer and adjust the packing density of the conductive layer by adjusting the shape of the conductive material And exhibits excellent electromagnetic wave shielding performance by decreasing the resistivity, and simultaneously exhibits conductivity, heat resistance, mechanical properties and flame retardancy.
1 is a schematic view showing a cross-sectional structure of an electromagnetic wave shielding film according to an embodiment of the present invention.
2 is a schematic view showing a cross-sectional structure of an electromagnetic wave shielding film according to an embodiment of the present invention.
3 is a schematic view illustrating a cross-sectional structure of an electromagnetic wave shielding film according to an embodiment of the present invention.
4 is a schematic view showing a cross-sectional structure of an electromagnetic wave shielding film according to an embodiment of the present invention.
5 is a view showing a manufacturing process of an electromagnetic wave shielding film according to the present invention.
6 is a view showing a process for producing a base film in the electromagnetic wave shielding film of the present invention.
7 is a view showing a process for producing a base film in the electromagnetic wave shielding film of the present invention.
Description of the Related Art
100, 110, 120, 130: electromagnetic wave shielding film
10, 200: insulating layer
20, 30: conductive adhesive layer
31: first conductive adhesive layer (upper layer)
32: Middle layer
33: second conductive adhesive layer (lower layer)
40, 50: release film
500: first base film
600: second base film
Hereinafter, the present invention will be described in detail.
An electromagnetic wave shielding film refers to a film which is laminated on the outermost portion (coverlay portion) of a flexible printed circuit board for electromagnetic interference (EMI) noise shielding. Such electromagnetic wave shielding films are required to have various physical properties, and they are required to have excellent electromagnetic wave shielding effect, bending property, excellent flame retardancy, thermal stability, chemical resistance, abrasion resistance, low resistance change and the like.
As a conventional electromagnetic wave shielding film, a film in which a conductive adhesive layer is laminated on one or more insulating layers is used. In order to increase the flame retardancy of such a shielding film, a flame retardant may be used as a component of the conductive adhesive layer. However, since the content of the conductive filler constituting the conductive adhesive layer is reduced by an amount corresponding to the amount of the flame retardant, the shielding effect of the electromagnetic shielding film is unsatisfactory .
On the other hand, in order to enhance the shielding effect, the use of a flame retardant as a component constituting the conductive adhesive layer is excluded, and the content of the conductive filler is increased more than the amount of the conventional flame retardant used. In this case, although the shielding property is improved, since the packing density of the conductive adhesive layer is limited in comparison with the content of the conductive filler, the synergistic effect is not so high in terms of the resistivity and shielding effect.
Accordingly, in the present invention, the use of a flame retardant as a component constituting the conductive adhesive layer of the electromagnetic wave shielding film is excluded, and the content of the conductive filler is increased more than the conventional amount of the flame retardant to constitute the flame retardant non- Characterized in that two or more conductive fillers having different shapes and different average particle diameters are mixed as the conductive adhesive layer component.
When the conductive fillers having different shapes are used in combination as described above, the packing density of the conductive adhesive layer is increased due to the increase of the contact points between the particles by mixing particles having different shapes and particle diameters, The resistivity value is decreased. Therefore, even when a small amount of conductive filler is used compared to the prior art, the electric / electromagnetic shielding property can be improved and the contact resistance between the flexible printed circuit board (FPCB) and the ground (GND) can be reduced. At the same time, conductivity, heat resistance and mechanical properties can be improved.
Further, since the conductive filler includes an electrically conductive metal material, a flame retarding effect can be achieved.
In addition, in the present invention, a polyimide layer formed from a commercially available polyimide film and polyamic acid can be used as an insulating layer of an electromagnetic wave shielding film. Due to the inherent flame retardancy of such a polyimide (PI) The flame retardant effect equivalent to that of the conventional flame retardant-containing electromagnetic wave shielding film can be exhibited.
<Electromagnetic wave shielding film>
Hereinafter, an electromagnetic wave shielding film for forming a flexible printed circuit board (FPCB) according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
The electromagnetic wave shielding film of the present invention can be largely divided into an insulating layer and a conductive layer, wherein the conductive layer includes a conductive adhesive layer.
1 to 4, the electromagnetic
≪ Insulating layer &
In the electromagnetic wave shielding film of the present invention, the insulating
The insulating layer may be formed by curing a thermosetting composition including a conventional thermosetting resin and a curing agent known in the art as a coating layer or a film.
In the present invention, a conventional polyimide resin known in the art may be used as the insulating
For example, the polyimide-based resin may be prepared by using a commercially available polyimide (PI) film or a resin composition containing at least one selected from the group consisting of polyimide, polyamide, polyamideimide and polyamic acid resin Or may be a thermoplastic polyimide layer formed by applying a liquid on a film and curing it. Or a soluble soluble polyimide (soluble PI) may be used.
The polyimide (PI) resin is a polymer substance having an imide ring, and exhibits excellent flame retardancy, heat resistance, ductility, chemical resistance, abrasion resistance and weather resistance based on the chemical stability of the imide ring. Low thermal expansion rate, low air permeability and excellent electrical properties. Therefore, when the polyimide film is used as an insulating layer, the flame retardancy of the electromagnetic wave shielding film can be sufficiently secured even if the flame retardant is not contained due to the flame retardancy of the polyimide itself. In addition, surface hardness is increased compared to epoxy or other resins, scratch resistance is increased, heat resistance is increased due to a high glass transition temperature, and flexural strength is higher than epoxy resin.
The polyimide film may be in the form of a film or sheet having a self-supporting property. In this case, a commercially available polyimide (PI) film or a commercially available soluble polyimide may be used, or a condensation reaction of a diamine compound and a tetracarboxylic acid compound may be carried out according to a method known in the art And then coating and drying / curing these reactants on a substrate.
At this time, the composition for forming a polyimide layer may be composed of a polyimide (PI) first resin and a surfactant, and may further include a second resin such as an epoxy resin if necessary. The polyimide (PI) is preferably a thermosetting polyimide, and examples of the polyimide resin that can be used include, but are not limited to, polyimide, polyamideimide, or a composite resin thereof.
Here, the polyimide resin may be prepared by imidizing a polyamic acid varnish obtained through imidization reaction between a conventional aromatic dianhydride and an aromatic diamine (or aromatic diisocyanate) known in the art. An additive such as an inorganic filler or a thermoplastic resin may be added as needed for the purpose of imparting appropriate flexibility to the resin composition after curing. Examples of such a thermoplastic resin include phenoxy resin, polyvinyl acetal resin, polyethersulfone, polysulfone, and the like. Any one of these thermoplastic resins may be used alone, or two or more of them may be used in combination. The polyimide film may be subjected to a surface treatment such as a mat treatment or a corona treatment.
When the polyimide film, the soluble polyimide or the polyamic acid composition described above is used in the present invention, conventional thermosetting resins known in the art such as phosphorus (P) type thermosetting resin and / or phosphorus (P) Resin can be used.
Non-limiting examples of thermosetting resins usable in the present invention include epoxy resin, polyurethane resin, phenol resin, vegetable oil-modified phenol resin, xylene resin, guanamine resin, diallyl phthalate resin, vinyl ester resin, unsaturated polyester resin , A furan resin, a polyimide resin, a cyanate resin, a maleimide resin, and a benzocyclobutene resin. Preferably, it is an epoxy resin, a phenol resin or a vegetable rubidic phenolic resin. The double epoxy resin is preferred because of its excellent reactivity and heat resistance. Here, the thermosetting resin may be a phosphorus-containing thermosetting resin, a phosphorus-containing thermosetting resin, or both.
The epoxy resin may be any conventional epoxy resin known in the art, and it is preferable that two or more epoxy groups are present in one molecule.
Examples of usable epoxy resins include, but are not limited to, bisphenol A type / F type / S type resin, novolak type epoxy resin, alkylphenol novolak type epoxy resin, biphenyl type, aralkyl type, naphthol Naphthol type, dicyclopentadiene type, or mixed form thereof.
More specific examples thereof include epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, naphthalene type epoxy resin, anthracene epoxy resin, biphenyl type epoxy resin, Cresol novolak type epoxy resin, bisphenol A novolak type epoxy resin, bisphenol S novolak type epoxy resin, biphenyl novolac type epoxy resin, naphthol novolak type epoxy resin, naphthol phenol coaxial novolak type epoxy resin , Naphthol cholizole co-novolak type epoxy resin, aromatic hydrocarbon formaldehyde resin modified phenol resin type epoxy resin, triphenyl methane type epoxy resin, tetraphenyl ethane type epoxy resin, dicyclopentadiene phenol addition reaction type epoxy resin, phenol aral A quarternary epoxy resin, a polyfunctional phenol resin, a naphthol aralkyl type epoxy resin There is. At this time, the above-mentioned epoxy resin may be used alone, or two or more epoxy resins may be used in combination.
In the present invention, conventional curing agents known in the art can be used without limitation, and can be appropriately selected depending on the type of epoxy resin to be used. Non-limiting examples of usable curing agents include phenol-based, anhydride-based, dicyanamide-based, and curing agents. Of these, phenolic curing agents are preferred because they can further improve heat resistance and adhesiveness. Non-limiting examples of the phenolic curing agent include phenol novolak, cresol novolac, bisphenol A novolac, naphthalene type, etc. These may be used alone or in combination of two or more.
The insulating layer according to the present invention may further comprise a conventional electrically nonconductive filler known in the art to effectively exhibit the mechanical properties and low resistance change of the final product.
The electrically nonconductive filler may be an organic filler, an inorganic filler, or a mixture thereof. Examples of the electrically nonconductive filler include natural silica, fused silica, amorphous silica, crystalline silica, And the like; Magnesium oxide, magnesia, clay, calcium silicate, titanium oxide, antimony oxide, glass fiber, aluminum borate, strontium titanate, calcium titanate (calcium titanate), talc , Magnesium titanate, bismuth titanate, titanium oxide, barium zirconate, calcium zirconate, boron nitride, silicon nitride, talc, mica and the like. These inorganic fillers may be used singly or in combination of two or more. Carbon black, grapheme, carbon nanotube (CNT), or a mixture of at least one of them may be used.
The content of the electrically nonconductive filler can be appropriately adjusted in consideration of the mechanical properties of the insulating layer, the change in resistance, and other physical properties of the insulating layer. For example, the content of the electrically nonconductive filler is in the range of 3 to 30 parts by weight, May range from 5 to 20 parts by weight.
In addition to the above-mentioned components, the thermosetting resin composition of the present invention may contain a flame retardant generally known in the art, or other thermosetting resins or thermoplastic resins not described above and oligomers thereof And other additives such as an antioxidant, a polymerization initiator, a dye, a pigment, a dispersant, a thickener, a leveling agent, and the like may be further included. Examples thereof include organic fillers such as silicone-based powder, nylon powder and fluororesin powder, thickeners such as orthobenzene and benzene; Polymer-based defoaming agents or leveling agents such as silicones and fluororesins; Adhesion-imparting agents such as imidazole-based, thiazole-based, triazole-based and silane-based coupling agents; And coloring agents such as phthalocyanine, carbon black and the like.
According to a preferred embodiment of the present invention, the insulating layer is a polyimide resin or a mixture of a polyimide resin and an epoxy resin, wherein the electrically conductive filler and an additive are included.
Preferable examples of the composition constituting the insulating layer include 60 to 80 parts by weight of a soluble polyimide resin based on 100 parts by weight as a whole; 5 to 10 parts by weight of an epoxy resin; 3 to 30 parts by weight of electrically conductive filler; And 2 to 5 parts by weight of coloring agent.
Here, the soluble polyimide resin can realize chemical resistance and bending property, and the bisphenol novolac epoxy resin exhibits chemical resistance and stiffness effect. In addition, the electrically conductive filler can secure abrasion resistance and pencil hardness, and the colorant such as carbon black can realize a color desired by the user.
In the electromagnetic wave shielding film of the present invention, the thickness of the insulating layer can be appropriately adjusted in consideration of handling property of the film, physical rigidity, thinning of the substrate, and the like. For example, in the range of 5 to 20 mu m, and preferably in the range of 5 to 6 mu m.
The insulating layer according to the present invention can constitute a single insulating layer made of polyimide (PI) instead of a plurality of insulating layers in the prior art, thereby ensuring flame retardancy, flexibility and chemical resistance based on the flame retardancy of the polyimide itself. In addition, the conductive filler to be added can exhibit characteristics of an abrasion resistance of 3,000 or more and a pencil hardness of 8 to 9H or more.
≪ Conductive adhesive layer &
In the electromagnetic wave shielding film of the present invention, the conductive
Further, since the function of fixing the electromagnetic wave shielding film to the adherend is also provided, it can be stably connected to the electric circuit of the printed circuit board when attached to the flexible printed circuit board (FPCB) It is possible to effectively prevent intrusion into the printed circuit board.
The conductive adhesive layer includes a thermosetting resin component and an electrically conductive filler in order to simultaneously exhibit the adhesive force with the base material and the electromagnetic wave shielding effect. The conductive adhesive layer is used as a component constituting the conductive adhesive layer of the electromagnetic wave shielding film, The conductive filler is added so that the content of the conductive filler is increased to constitute the flame retardant nonconductive type conductive adhesive layer while mixing two or more kinds of conductive fillers having different shapes as the conductive adhesive layer component .
When a conductive filler having a different shape as described above is used in combination, the packing density of the conductive adhesive layer is increased and the specific resistance value is reduced compared with the case of using the conductive filler of the same shape in the related art. Therefore, even if a small amount of conductive filler is used The excellent electrical / electromagnetic wave shielding property and the contact resistance between the flexible printed circuit board (FPCB) and the ground (GND) can be reduced.
In the present invention, the conductive adhesive layer containing two or more kinds of conductive fillers having different shapes exhibits a lower specific resistance value than the specific resistance [rho s ] of the conductive adhesive layer containing the conductive filler of the same shape. For example, the resistivity [rho d ] value of the conductive adhesive layer may be 1.0E-04 to 3.7E-04? Cm under the condition that the content of the conductive filler is 60 to 80% and the thickness is 10 m, May range from 1.0E-04 to 2.0E-04. The content of the conductive filler is preferably in the range of 60 to 77% by weight.
Here, the specific resistance value of the conductive adhesive layer may be in the range of 1.0E-04 to 1.5E-04? Cm based on 10 占 퐉 thickness of the conductive adhesive layer after hot pressing, and the sheet resistance may be 100 m? To 150 m OMEGA / sq. The contact resistance may also be in the range of 0.5 to 2.2 OMEGA, and preferably in the range of 0.5 to 1.00 OMEGA.
In the present invention, the two or more conductive fillers are not particularly limited to the shape and size of the conductive filler, as long as they have different shapes and can increase the packing density. And may be selected from the group consisting of spheres, flakes, needles, cones, pyramids and amorphous.
In order to improve the packing density and the resistivity reducing effect of the conductive adhesive layer, the conductive filler preferably mixes the spherical first conductive filler and the acicular-shaped second conductive filler. The average particle diameter d50 of the first conductive filler may be 2 to 2.5 占 퐉 and the average particle diameter d50 of the second conductive filler may be 7 to 9 占 퐉.
The conductive filler may be any conventional conductive filler known to those skilled in the art. For example, it may be a copper filler or a nickel filler coated with Ag, Cu, Ni, Al or Ag. A polymer filler, a filler obtained by metal plating on a resin ball or a glass bead, a mixture thereof, or the like. Here, silver (Ag) is expensive, copper (Cu) is insufficient in reliability of heat resistance, and aluminum (Al) Ni) filler is preferably used.
The content of the conductive filler is not particularly limited as long as it exhibits an electromagnetic wave shielding effect. For example, the conductive filler may be 60 to 80 parts by weight, preferably 65 to 77 parts by weight based on 100 parts by weight of the conductive adhesive layer. In the conductive adhesive layer, the content ratio of the first conductive filler to the second conductive filler may be 15 to 60:70 to 80 by weight based on the weight of each composition.
Resins usable in the conductive adhesive layer of the present invention may be any of conventional thermosetting resins known in the art.
The thermosetting resin may be composed of the same or different components as the thermosetting resin constituting the insulating layer. For example, a thermosetting resin containing and / or not containing phosphorus (P) may be used.
Examples of the thermosetting resin that can be used include, but are not limited to, epoxy resin, polyurethane resin, phenol resin, vegetable rubidic phenol resin, xylene resin, guanamine resin, diallyl phthalate resin, vinyl ester resin, unsaturated polyester resin, , A polyimide resin, a cyanate resin, a maleimide resin, and a benzocyclobutene resin. Preferably, the polyester-based modified urethane resin and the epoxy resin are used. The double-polyester-modified urethane resin is used for improving the lamination properties with other base layers and securing the flexibility, and the epoxy resin has a curing property of polyurethane, Reactivity, and heat resistance.
In the present invention, in addition to the above-mentioned urethane resin and epoxy resin, other thermosetting resin or thermoplastic resin known in the art may be further included. The thermoplastic resin may be a conventional resin known in the art. For example, one or more selected from the group consisting of a polyester resin, a polyamide resin, a polycarbonate resin and a modified polyphenylene oxide resin can be used have.
In the present invention, conventional curing agents known in the art may be further included. These can be appropriately selected depending on the kind of resin to be used. Non-limiting examples of usable curing agents include phenolic, anhydride, dicyanamide, and curing agents. When the thermosetting resin is an epoxy resin, a polyamine type curing agent, an acid anhydride type curing agent, boron trifluoride amine complex, imidazole type curing agent, aromatic diamine type curing agent, carboxylic acid type curing agent and phenol resin may be used. , A phenol-based curing agent is preferable because heat resistance and adhesiveness can be further improved.
In addition to the above-mentioned components, the conductive adhesive layer of the present invention may contain various additives such as flame retardants generally known in the art, other thermosetting resins, thermoplastic resins and oligomers thereof, And may further contain other additives such as a polymer, solid rubber particles or an ultraviolet absorber, an antioxidant, a polymerization initiator, a dye, a pigment, a dispersant, a thickener, a leveling agent, a colorant and the like.
On the other hand, in the conductive adhesive layer of the present invention, the components constituting the conductive adhesive layer, for example, the first conductive filler and the second conductive filler, which are different in shape from the resin, are uniformly distributed as a whole, It may have a different composition.
As a preferable example of the conductive adhesive layer, the conductive adhesive layer includes a first conductive adhesive layer (upper layer) and a second conductive adhesive layer (lower layer) positioned on both surfaces with reference to the thickness direction. The first conductive adhesive layer, the intermediate layer, and the second conductive adhesive layer may have different compositions of the first conductive filler and the second conductive filler, which have different shapes, respectively.
More specifically, it is preferable that the first conductive filler and the second conductive filler are located in the first conductive adhesive layer and the second conductive adhesive layer, respectively, and the first conductive filler and the second conductive filler are mixed in the intermediate layer Do.
Accordingly, the conductive adhesive layer of the present invention can have a gradient profile in which the packing density increases from both surfaces to the intermediate layer with respect to the thickness direction.
In the electromagnetic wave shielding film of the present invention, the thickness of the conductive adhesive layer can be appropriately adjusted in consideration of electromagnetic wave shielding force, bending property, adhesive force, interlayer adhesive force, and the like of the film. For example, in the range of 3 to 10 mu m.
In addition, the conductive adhesive layer according to the present invention can secure a high adhesive force with a cover printed on a flexible printed circuit board (FPCB). For example, when the adhesive force value with the cover layer is 1.0 kgf / cm or more in the C- . The bendability of the conductive layer may be equivalent to that of the conventional flexible copper clad laminate (FCCL).
In the present invention, it is possible to maintain a low contact resistance between the conductive adhesive layer and the GND of the FPCB. At this time, the electromagnetic wave shielding power may be in the range of 50 to 65 dB at a frequency of 1 GHz in the ASTM 4935-1 method, May be 55 to 65 dB.
According to a preferred embodiment of the present invention, the electromagnetic
The release film may be any conventional plastic film known to those skilled in the art without limitation.
Examples of usable plastic films include polyester films such as polyethylene terephthalate (PET), polybutylene terephthalate and polyethylene naphthalate, polyethylene films, polypropylene films, cellophane, diacetylcellulose films, triacetylcellulose films, acetylcellulose Polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, polymethylpentene film, polysulfone film, polyetheretherketone film , A polyethersulfone film, a polyetherimide film, a polyimide film, a fluororesin film, a polyamide film, an acrylic resin film, a norbornene resin film, and a cycloolefin resin film. These plastic films may be either transparent or semitransparent, and may be colored or non-colored, and may be appropriately selected depending on the application. Preferably, transparent polyethylene terephthalate (PET) is used.
In the present invention, the first release film and the second release film are respectively disposed on the insulating layer and the conductive adhesive layer. At this time, in consideration of the bonding process between the flexible printed circuit board and the electromagnetic shielding film, it is preferable that the interlayer adhesive force between the insulating layer and the first release film is adjusted to be higher than the interlayer adhesion force between the conductive adhesive layer and the second release film. The mold releasing force of the release film may be in the range of 10 to 500 gf / inch. For example, the release force of the first release film may range from 30 to 200 gf / inch, and the release force of the second release film may range from 10 to 30 gf / inch.
To this end, the first release film disposed on the insulating layer is subjected to surface treatment by an oxidation method, an irregularization method or the like on one surface or both surfaces, if necessary, for the purpose of improving adhesion with an insulating layer provided on the surface of the first release film can do.
Examples of the oxidation method include a corona discharge treatment, a plasma treatment, a chromic acid treatment (wet), a flame treatment, a hot air treatment, an ozone / ultraviolet ray irradiation treatment and the like. a sand blast method, a solvent treatment method, and the like. These surface treatment methods are appropriately selected depending on the kind of the base film, but generally mat treatment and corona discharge treatment are preferable in terms of effect and operability. Or beads inside the release film.
According to a preferred embodiment of the present invention, the
The thickness of the release films (40, 50) is not particularly limited and is adjustable within the conventional range known in the art. The release film may be disposed on the insulating layer and the conductive adhesive layer. The thickness of the upper release film (first release film) contacting the insulation layer may be in the range of 50 to 75 mu m, and the lower release film (Second release film) may range from 75 to 150 mu m.
According to another example of the present invention, a release layer may be included on the
The component of the releasing agent used in the releasing layer is not particularly limited, and conventional releasing agent components known in the art can be used. Non-limiting examples thereof include epoxy-based releasing agents, releasing agents comprising fluororesins, silicone-based releasing agents, alkyd resin-based releasing agents, and water-soluble polymers. The thickness of the release layer can be appropriately adjusted within the conventional range known in the art.
According to a preferred embodiment of the present invention, the
If necessary, a powdery filler such as silicon, silica, or the like may be included as a component of the release layer. In this case, the powder filler of the particulate form may be mixed with two types of powder fillers, and the average particle size of the powder fillers may be appropriately selected in consideration of the surface roughness to be formed.
The method for forming the releasing layer is not particularly limited, and known methods such as hot press, heat roll laminate, extrusion laminate, application of a coating liquid, and drying can be employed.
The electromagnetic wave shielding film according to the present invention can have four embodiments. However, the present invention is not limited to the following embodiments, and various modifications and applications are possible as needed.
1 is a cross-sectional view showing a first embodiment of an electromagnetic wave shielding film according to the present invention.
The electromagnetic wave shielding film includes an insulating
2 is a cross-sectional view showing a second embodiment of the electromagnetic wave shielding film according to the present invention.
The electromagnetic wave shielding film includes an insulating
3 is a cross-sectional view showing a third embodiment of the electromagnetic wave shielding film according to the present invention.
The electromagnetic wave shielding film includes an insulating
4 is a cross-sectional view showing a fourth embodiment of the electromagnetic wave shielding film according to the present invention.
The electromagnetic wave shielding film includes an insulating
The electromagnetic wave shielding film for forming a flexible printed circuit board according to the present invention can be produced by a conventional method known in the art.
Hereinafter, preferred two methods of the production method are described below, but the method is not particularly limited thereto, and the steps of each step may be modified or optionally mixed with each other if necessary.
In one preferred embodiment of the method for producing an electromagnetic wave shielding film, (i) forming an insulating layer on a first surface of a first base film ('S10 step'); (ii) coating a second conductive resin composition comprising a needle-shaped second conductive filler and a resin on a first side of a second base film and then drying to form a second conductive adhesive layer (step 'S20'); (iii) forming a first conductive adhesive layer by coating a first conductive resin composition including a spherical first conductive filler and a resin on the insulating layer formed of the first base film, and drying the coated first conductive adhesive composition (step S30); And (iv) stacking the first base film and the second base film so that the first conductive adhesive layer of the first base film and the second conductive adhesive layer of the second base film are in contact with each other, (Step < RTI ID = 0.0 > S40). ≪ / RTI >
First, 1) a resin composition for forming an insulating layer is coated on the first surface of the first base film and dried to form an insulating layer (step S10).
The first base film may be any conventional plastic film known in the art without limitation. For example, the first base film may have the same structure as the release film described above. Preferably a transparent PET film.
It is preferable that a surface roughness is formed on the first surface of the first base film before coating the insulating layer on the first base film to secure the adhesive force between one base film and the insulating layer.
At this time, the surface roughness may be formed by forming a predetermined surface roughness according to a conventional unevenness method known in the art.
For example, as shown in Figs. 6 (a) to 6 (c), a sandblast method is applied to a first surface of a first base film, and then a first surface Coated with a release agent. Here, the releasing agent may be any conventional composition known to those skilled in the art without limitation, and may preferably include acrylic urethane (subject), silicone varnish, and isocyanate-based curing agent. In addition, a method of transferring a surface roughness surface to form a predetermined surface roughness surface can also be carried out.
The surface roughness (Ra) formed on the first surface of the first base film is not particularly limited as long as it can increase the adhesive strength, and may be in the range of 0.2 mu m to 3.0 mu m, for example.
Examples of the organic solvent usable in preparing the resin composition for forming the insulating resin layer include ketones such as acetone, methyl ethyl ketone and cyclohexanone, ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate , And carbitol acetate; carbohydrates such as cellosolve and butyl carbitol; aromatic hydrocarbons such as toluene and xylene; dimethylformamide; dimethylacetamide; and N-methylpyrrolidone. The organic solvents may be used alone or in combination of two or more.
In the present invention, a preferable example of the resin composition constituting the insulating layer includes 60 to 80 parts by weight of a soluble polyimide resin based on 100 parts by weight of the whole resin composition; 5 to 10 parts by weight of an epoxy resin; 3 to 30 parts by weight of electrically conductive filler; And 2 to 5 parts by weight of coloring agent.
Here, the soluble polyimide resin implements the chemical resistance and the bending property, and the epoxy resin plays a role of exhibiting the chemical resistance and the stiffness effect. In addition, the electrically conductive filler ensures abrasion resistance and pencil hardness, and the colorant such as carbon black can realize a color desired by the user.
When the resin composition for forming an insulating layer is applied on a base film, the resin composition for forming an insulating layer may be applied to a base film such as a roll coater, a bar coater, a comer coater, a blade coater, a lip coater, a rod coater, a squeeze coater, a reverse coater, A thermosetting resin composition may be coated on a substrate with a coater and dried at a temperature of 120 to 160 DEG C for 1 to 30 minutes. The insulating layer formed in the above step is preferably in a cured state.
2) A second conductive resin composition containing a needle-shaped second conductive filler and a resin is coated on the second base film and dried to form a second conductive adhesive layer (step S20).
The second base film may also be made of any conventional plastic film known in the art without limitation, and a mold release map can be used. The second base film may be the same as or different from the first base film. Preferably a transparent PET film.
It is preferable to form a surface roughness on the first surface of the second base film so as to secure the adhesive force between the second base film and the second conductive adhesive layer before coating the second conductive adhesive layer on the second base film.
At this time, the surface roughness may be formed by forming a predetermined surface roughness according to a conventional method known in the art.
For example, as shown in Fig. 7 (b), a predetermined surface roughness can be formed by fine particles by applying a releasing agent containing fine particles such as silica onto the first surface of the second base film. The composition of the releasing agent is not particularly limited, and examples thereof may include acrylic urethane (subject), silicone varnish, isocyanate curing agent, and powdered filler such as silicon, silica and the like. In this case, the powder filler of the particulate form may be mixed with two types of powder fillers, and the average particle size of the powder fillers may be appropriately selected in consideration of the surface roughness to be formed. In addition, a method of transferring a surface roughness surface to form a predetermined surface roughness surface can also be carried out.
The surface roughness (Ra) formed on the first surface of the second base film is not particularly limited as long as it can increase the adhesive strength, and may be in the range of 0.2 mu m to 3.0 mu m, for example.
In the present invention, a preferable example of the resin composition constituting the second conductive adhesive layer includes 10 to 25 parts by weight of polyurethane based on 100 parts by weight of the total resin composition; 4 to 20 parts by weight of an epoxy resin; And 60 to 80 parts by weight of the second conductive filler of the dendrite type. At this time, the content of the acicular-shaped second conductive filler may be more than 150 parts by weight and not more than 400 parts by weight based on 100 parts by weight of the resin constituting the second conductive adhesive layer. The epoxy resin may be used in combination of two or more kinds, and the content of each epoxy resin may be 2 to 10 parts by weight.
Here, the polyurethane resin is for securing the adhesion to homology and an adherend, and the epoxy resin serves to cure the polyurethane. Also, the needle-shaped filler plays a role in ensuring conductivity implementation and shielding rate implementation.
In the present invention, when the resin composition for forming the second conductive adhesive layer is applied to the second base film, a roll coater, a bar coater, a comer coater, a blade coater, a lip coater, a rod coater, a squeeze coater, A transfer roller coater, a gravure coater, a spray coater, or the like, and drying it at a temperature of 100 to 150 ° C for 1 to 30 minutes.
3) A first conductive resin composition including a spherical first conductive filler and a resin is coated on the insulating layer on the first base film and dried to form a first conductive adhesive layer (step S30).
In the present invention, a preferable example of the resin composition for forming the first conductive adhesive layer includes 30 to 70 parts by weight of polyurethane based on 100 parts by weight of the whole resin composition; 10 to 40 parts by weight of an epoxy resin; And 15 to 60 parts by weight of the spherical first conductive filler. At this time, the content of the spherical first conductive filler may be more than 100 parts by weight and less than 150 parts by weight based on 100 parts by weight of the resin constituting the first conductive adhesive layer.
Here, the polyurethane resin is a polyester-based modified urethane resin for improving the lamination property with the second conductive adhesive layer and securing flexibility, and the epoxy resin serves to cure the polyurethane. Also, the spherical first conductive filler plays a role of realizing conductivity and realization of shielding rate, and thereafter, permeates between the acicular-shaped second conductive fillers at the time of pressurization to increase the packing density between the particles to increase the conductivity It plays a role. Accordingly, it is possible to realize a low resistivity and a high shielding efficiency in spite of applying a small amount of filler to the conventional single layer structure.
The method of forming the first conductive adhesive layer may be the same as the method of forming the second conductive adhesive layer.
4) The first conductive adhesive layer of the first base film and the second conductive adhesive layer of the second base film are disposed so as to be in contact with each other, and then the first base film and the second base film are pressed together through a pressing process Step S40 ").
In the present invention, the conditions of the pressing process can be appropriately adjusted within the conventional range known in the art. For example, thermocompression Lami. The conditions for the process (roll to roll) are not particularly limited, but may be performed at a temperature of 50 to 130 ° C, a pressure of 3 to 50 kgf / cm 2 , and a compression rate of 3 m / min to 20 m / min.
At this time, the first base film in which the sheet-like first base film and the insulating layer are sequentially laminated, and the second conductive adhesive layer and the second base film on which the first conductive adhesive layer is formed are wound in rolls and laminated continuously Alternatively, it is also possible to perform lamination after cutting both sheets in a roll form.
After the above step, the above-mentioned electromagnetic wave shielding film can be slit to an appropriate size. The electromagnetic wave shielding film of the present invention manufactured as described above may have a structure as shown in FIGS. 2 and 4.
In another preferred embodiment of the method for manufacturing an electromagnetic wave shielding film according to the present invention, there is provided a method of manufacturing an electromagnetic wave shielding film, comprising the steps of: (i) forming an insulating layer on a first surface of a first base film; (ii) coating a resin composition for forming a conductive adhesive layer containing two or more conductive fillers and a resin having different shapes on the insulating layer and then drying to form a conductive adhesive layer.
In this case, the second base film may be laminated on the formed conductive adhesive layer, followed by pressing through a pressing process. The electromagnetic wave shielding film of the present invention manufactured as described above may have a structure as shown in FIGS. 1 and 3.
<Electromagnetic wave shielding type flexible printed circuit board>
The present invention provides an electromagnetic wave shielding type flexible printed circuit board (FPCB) including the above-described electromagnetic wave shielding film.
More specifically, the printed circuit board includes a substrate including at least one circuit pattern; And an electromagnetic wave shielding film disposed on one side or both sides of the substrate.
In the present invention, the above-described electromagnetic wave shielding film may be laminated on a substrate (e.g., a printed circuit board) including a circuit pattern of one or more layers, preferably a coverlay of a flexible printed circuit board (FPCB)
At this time, the bonding between the flexible printed circuit board and the electromagnetic wave shielding film can be performed by a conventional method known in the art. For example, it may be bonded by an adhesive, or may be bonded in a non-adhesive form without using an adhesive.
In one preferred embodiment of the manufacturing process of the EMI shielding film for a flexible printed circuit board, for example, (i) a step of laminating the electromagnetic wave shielding film on the flexible printed circuit board cover layer, removing the first base film provided on the conductive adhesive layer side Stacking the exposed conductive adhesive layer on the coverlay of the flexible printed circuit board and thermocompression bonding; And (ii) removing the second base film located at the top of the squeeze.
The flexible printed circuit board may be a flexible copper clad laminate (FCCL) having a cover layer, for example, a copper foil layer and a cover layer sequentially stacked on a polyimide (PI). The printed circuit board in the present invention refers to a printed circuit board laminated in a single layer or two to three or more layers by a plating through hole method, a build-up method, or the like, and may be a sectional shape or a double-sided type.
The conditions for the thermocompression bonding step are not particularly limited. For example, the thermocompression bonding step may be performed at a temperature of 150 to 170 DEG C, a pressure of 30 to 60 kgf / cm < 2 >
In the present invention, excellent electromagnetic wave shielding performance can be exhibited by bonding the electromagnetic wave shielding film on the flexible printed circuit board as described above.
Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following Examples and Experimental Examples are merely illustrative of the present invention, and the scope of the present invention is not limited by the following Examples and Experimental Examples.
[Examples 1 to 10]
1-1. Preparation of insulating layer coating liquid
75 wt% of a liquid Soluble polyimide resin (Arakawa Chemical PIAD-100) and 6 wt% of a bisphenol novolak epoxy resin (National Chemical Co., Ltd. YDCN-500 90P) were mixed first. 4 wt% of carbon black (COLUMBIA CHEMICALS) and 15 wt% of non-electrically conductive filler (Admatec SC2050) as a coloring agent were mixed and dispersed in the primary mixed polyimide and epoxy resin to prepare an insulating layer coating solution.
1-2. Preparation of coating liquid for forming first conductive adhesive layer [1A to 1C]
, 32% by weight of a polyurethane resin (NINUX NPE-2200) as a thermoplastic resin, 60% by weight of a spherical conductive filler having an average particle diameter of 2.5 占 퐉 (Mumi MCS30C-10P, N-NH2-NH2) was mixed and dispersed using a planetary mixer to prepare a first conductive adhesive layer coating solution.
(wt%)
(wt%)
(wt%)
(wt%)
1-3. Preparation of coating liquid for forming second conductive adhesive layer (2C-1)
75 wt% of a spherical conductive filler (MUMMU MCS30C-10P) having a mean particle size of 3 to 4 mu m, a polyurethane resin (NUNU NPE-2200) as a thermoplastic resin, 75 wt% of a bisphenol A type epoxy resin as a thermosetting resin and a polyurethane curing agent 2.25% by weight of a non-halogen flame-retardant epoxy resin (NANUX NH-E220) and 2.25% by weight of a non-halogen flame retardant epoxy resin (National Kagaku KDP555) were mixed and dispersed using a planetary mixer to prepare a second conductive adhesive layer coating solution 2C-1.
1-4. Preparation of coating solution for forming second conductive adhesive layer (2C-2)
75% by weight of a plate-like conductive filler (Moon Cu @ 10Ag) having an average particle diameter of 5.5 탆 instead of a spherical conductive filler having an average particle diameter of 3 to 4 탆, which is the same as the coating liquid composition for forming the second conductive adhesive layer of 1-3 with a spherical conductive filler. Were used.
1-5. Preparation of coating liquid for forming second conductive adhesive layer (2C-3)
(Mitsui ACBY-2) 75 having an average particle size of 7 to 9 mu m instead of the spherical conductive filler having an average particle size of 3 to 4 mu m, in the same manner as the coating liquid composition for forming the second conductive adhesive layer 1-3 using the spherical conductive filler % By weight.
(wt%)
(wt%)
(wt%)
(wt%)
(wt%)
1-6. Manufacture of electromagnetic wave shielding film
An insulation layer was formed on the first surface of the prepared first base film by comma coating and dried at a maximum temperature of 160 캜 for 3 minutes and 30 seconds to form a cured state of 5 to 6 탆 Thereby forming an insulating layer.
Then, the second conductive adhesive layer-forming coating liquid prepared in 1-3 to 1-5 on the first surface of the second base film thus prepared was applied with a comma coating to form a second conductive adhesive layer and dried at a maximum temperature of 150 캜 for 3 minutes and 30 seconds To form a semi-cured second conductive adhesive layer having a thickness of 15 to 17 mu m. Then, the first conductive adhesive layer-forming coating liquid prepared in 1-2 was formed on the insulating layer formed on the first base film by gravure coating to form a first conductive layer and dried to form a first conductive adhesive layer having a thickness of 1 to 3 탆 .
Thereafter, the first conductive adhesive layer and the second conductive adhesive layer formed on the insulating layer were arranged so as to be in contact with each other, and then pressed through a heat pressing process to produce an electromagnetic wave shielding film for a flexible printed circuit board.
[Comparative Examples 1 to 3]
The electromagnetic wave shielding film is produced as in the above 1-6 except that the first conductive adhesive layer is not formed on the insulating layer formed on the first base film and the insulating layer on the first base film and the second conductive The adhesive layers were arranged so as to be in contact with each other, and then pressed through a heat pressing step to produce an electromagnetic wave shielding film for a flexible printed circuit board.
The laminated structure of the electromagnetic wave shielding films prepared in Examples 1 to 10 and Comparative Examples 1 to 3 and the coating thicknesses of the respective layers are shown in Table 3 below.
(Coating thickness)
(Coating thickness)
(Coating thickness)
(6 탆)
[Evaluation example] Evaluation of electromagnetic wave shielding film
The following properties of the electromagnetic wave shielding films prepared in Examples 1 to 10 and Comparative Examples 1 to 3 were evaluated, respectively, and the results are shown in Table 4 below.
1) Adhesion
After the prepared second base film was removed, the conductive adhesive layer was disposed so as to be in contact with a 50 탆 PI film (SKC Kolon), laminated at 80 to 100 캜, and then the upper first base film was removed.
To form the support layer of the laminated adhesive force evaluation coupon, a bonding sheet and a prepreg impregnated with a resin in a glass fiber matrix were laminated on the bottom of a 50 mu m PI film, and a bonding sheet and a 25 mu m PI film (SKC Kolon) was laminated and subjected to a pressing process at a temperature of 150 ° C for 60 minutes under a pressure of 35 kgf per unit area to completely cure the insulating layer and the conductive adhesive layer.
The fully cured coupon was measured for a 90 degree (vertical) adhesive force (kgf / cm) for the PI film at a pulling rate of 50 mm / min.
2) Heat Resistance Characteristics (Solder Deeping)
After the second base film of the prepared electromagnetic wave shielding film was removed, the 25 μm-thick PI film (SKC Kolon) was placed in contact with the conductive adhesive layer, and the conductive adhesive layer was completely cured by a compression process at 150 ° C. for 60 minutes under a pressure of 35 kgf per unit area The upper first base film was removed.
The electromagnetic wave shielding film from which the upper first base film was removed was immersed in a 300 ° C water bath for 10 seconds to observe the appearance of defects such as lifting and cracking of the electromagnetic wave shielding film and color change of the insulating layer. In this case, it was judged as NG when the appearance defects such as lifting and cracking occurred, and when the appearance defects such as lifting and cracking were not found, it was judged as Pass.
3) Evaluation of chemical resistance in insulating layer:
Evaluation of Heat Resistance Characteristic The coupon was produced by the lamination and compression process in the same manner as the coupon manufacturing method, and the upper first base film was removed. An electromagnetic wave shielding film from which the upper first base film was removed was immersed in an aqueous solution of HCl (2 mol / L) for 10 minutes to prepare a coupon.
The electromagnetic wave shielding film from which the upper first base film was removed was immersed in an aqueous solution of HCl (3%) and H 2 SO 4 (5%, NaOH (5%)) for 30 minutes to prepare a coupon. The chemical resistance of the insulating layer was evaluated based on ASTM D 3359 for the evaluation coupon which was immersed.
4) Pencil Hardness
The hardness of the coating film was measured using the strength of graphite, which is the core of a pencil. First, the upper first base film was removed by producing a coupon by a lamination and pressing process in the same manner as the heat resistance evaluation coupon manufacturing method.
The pencil was shaved bluntly by the strength of the pencil, and the underside of the shim was smoothly rubbed with fine sandpaper. Thereafter, the upper first base film was pushed three times with a weight of 500 g so that the pencil lead reached the surface of the insulating layer of the electromagnetic wave shielding film from which the upper first base film was removed, and the insulating layer was peeled off or judged based on scratches.
5) Evaluation of electromagnetic wave shielding rate
Evaluation of Heat Resistance Characteristic The coupon was produced by the lamination and compression process in the same manner as the coupon manufacturing method, and the upper first base film was removed. The electromagnetic wave shielding rate for the frequency range of 30 MHz to 1 GHz was measured according to ASTM 4935-1. At this time, the tester used the Agilent 8719C Network Analyzer.
6) Contact resistance measurement
Two inner layer circuits were formed on the prepared cross-section FCCL with a width of 5 mm, a length of 50 mm and a spacing distance of 10 mm.
PI film 12.5 탆 and adhesive layer 15 탆 so that a square having a diameter of 0.15 mm and an area of 5 mm x 5 mm is positioned at the end of the inner layer circuit, Was subjected to a thermocompression bonding process at 150 DEG C for 60 minutes. The electroless gold plating was applied to the inner layer circuit which exposed copper by 0.15mm and 5mm × 5mm size by the coverlay punched out after the thermocompression process.
After the second base film of the prepared electromagnetic wave shielding film was removed, the electromagnetic wave shielding film was cut and layered in a width of 10 mm in the area of 0.15 mm located at the center of the inner layer circuit, and thermocompression process was performed at 150 캜 for 60 minutes at 35 kgf per unit area. The contact resistances of the two inner layer circuits exposed to a size of 5 mm were measured.
7) Measuring sheet resistance (conductivity) and resistivity (volume resistance)
After the second base film of the prepared electromagnetic wave shielding film was removed, the 25 μm thick release PET film (SKC Kolon) was placed so as to be in contact with the conductive adhesive layer, followed by compression at 150 ° C. for 60 minutes under a pressure of 35 kgf per unit area, And the upper first base film and the release film were removed.
The method of measuring the sheet resistance is measured by the 4-terminal method according to the method of ASTM F-43-93. The resistivity is measured according to the method of ASTM F-43-93, and the specific resistance is calculated based on the following equation with the measured sheet resistance.
[Mathematical Expression]
Surface Resistance x Thickness of Test Material (Specimen) = Resistivity
(Solder)
(Cross cut)
Hardness
(dB)
Resistance (Ω)
(Ωcm)
> 1.0kgf
Pass
5B
9H
10 탆
Generally, as the thickness of the conductive layer is thicker, the electromagnetic wave shielding film exhibits better resistivity and shielding ratio.
On the other hand, as shown in Table 4, the properties of the electromagnetic wave shielding film were confirmed in the conductive adhesive layer in the condition that the content and the thickness of the conductive filler were fixed under the same conditions. As a result, in Examples 1 to 10 in which conductive fillers of different shapes were mixed, It was confirmed that they exhibited excellent characteristics in terms of contact resistance, resistivity and shielding ratio as compared with Comparative Examples 1 to 3 using conductive filler.
Claims (20)
An electromagnetic wave shielding film comprising a conductive adhesive layer comprising two or more conductive fillers and a resin having different shapes and having an electromagnetic wave shielding ratio of 50 to 65 dB at a frequency of 1 GHz in the ASTM 4935-1 method,
Wherein the conductive adhesive layer comprises a first conductive adhesive layer having different compositions based on the thickness direction of the conductive adhesive layer; A second conductive adhesive layer; And an intermediate layer disposed therebetween,
Wherein the first conductive adhesive layer includes a first conductive filler,
Wherein the second conductive adhesive layer has a second conductive filler having a shape different from that of the first conductive filler,
Wherein the intermediate layer has a first conductive filler and a second conductive filler having different shapes mixed,
The packing density increases from the first conductive adhesive layer and the second conductive adhesive layer located on both surfaces of the conductive adhesive layer toward the intermediate layer,
When the content of the conductive filler in the conductive adhesive layer is 60 to 80 wt% and the thickness of the conductive adhesive layer is 10 m, the value of the resistivity [rho d ] of the conductive adhesive layer is in the range of 1.0E-04 to 3.7E-04 [ Wherein the electromagnetic wave shielding film is made of a metal.
When the thickness of the conductive adhesive layer after hot pressing is 10 占 퐉, the specific resistance? D of the conductive adhesive layer is 1.0E-04 to 1.5E-04 Lt; RTI ID = 0.0 > ohm-cm. ≪ / RTI >
Wherein the two or more conductive fillers are selected from the group consisting of spherical, flake, needle, cone, pyramid and amorphous.
Wherein the conductive filler is a mixture of a spherical first conductive filler and an acicular-shaped second conductive filler.
The average particle diameter (d50) of the first conductive filler is 2 to 2.5 占 퐉,
And the average particle diameter (d50) of the second conductive filler is 7 to 9 占 퐉.
Wherein the content of the conductive filler is 60 to 80 parts by weight based on 100 parts by weight of the conductive adhesive layer.
Wherein the content ratio of the first conductive filler to the second conductive filler in the conductive adhesive layer is 15 to 60:70 to 80 by weight.
Wherein the conductive adhesive layer has a value of adhesive force of 1.0 kgf / cm or more with the coverlay in a C-stage state.
Wherein the insulating layer, the conductive adhesive layer, or both the insulating layer and the conductive adhesive layer contain a flame retardant.
Wherein the resin constituting the insulating layer and the conductive adhesive layer is a thermosetting resin.
The insulating layer may be formed by applying a resin composition containing at least one selected from the group consisting of polyimide (PI) film, polyimide, polyamide, polyamideimide, and polyamic acid resin onto a base film and then curing Wherein the thermoplastic polyimide layer is a thermoplastic polyimide layer formed.
Wherein the insulating layer further comprises 3 to 30 parts by weight of an electrically nonconductive filler based on 100 parts by weight of the insulating layer.
The thickness of the insulating layer after hot pressing is in the range of 5 to 6 mu m,
Wherein the thickness of the conductive adhesive layer is 8 to 13 占 퐉.
The electromagnetic wave shielding film comprising: a first release film disposed on an insulating layer; And a second release film disposed on the conductive adhesive layer,
Wherein a predetermined surface roughness is formed on the first surface of the first release film in contact with the insulating layer and on the first surface of the second release film in contact with the conductive adhesive layer.
The electromagnetic wave shielding film according to any one of claims 1 to 10, which is disposed on one side or both sides of the substrate, according to any one of claims 3 to 8, and 12 to 19.
(FPCB). ≪ / RTI >
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| PCT/KR2016/009600 WO2017111254A1 (en) | 2015-12-21 | 2016-08-29 | Electromagnetic wave shielding film and manufacturing method therefor |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| KR20200049085A (en) * | 2018-10-31 | 2020-05-08 | 주식회사 두산 | Electromagnetic interference shielding film and flexible printed circuit board the same |
| KR20220108635A (en) * | 2021-01-27 | 2022-08-03 | 도레이첨단소재 주식회사 | Conductive adheisive composition and electromagnetic wave shielding film comprising the same |
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| US20040172502A1 (en) * | 2003-02-13 | 2004-09-02 | Lionetta William G. | Composite EMI shield |
| US20080014528A1 (en) * | 2006-07-17 | 2008-01-17 | Richard Kevin Bailey | Metal compositions, thermal imaging donors and patterned multilayer compositions derived therefrom |
| KR100995563B1 (en) * | 2010-05-04 | 2010-11-19 | 주식회사 이녹스 | Electrical conductive adhesive film for emi shielding |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| KR20200049085A (en) * | 2018-10-31 | 2020-05-08 | 주식회사 두산 | Electromagnetic interference shielding film and flexible printed circuit board the same |
| KR102537333B1 (en) * | 2018-10-31 | 2023-05-26 | 주식회사 두산 | Electromagnetic interference shielding film and flexible printed circuit board the same |
| KR20220108635A (en) * | 2021-01-27 | 2022-08-03 | 도레이첨단소재 주식회사 | Conductive adheisive composition and electromagnetic wave shielding film comprising the same |
| KR102451057B1 (en) | 2021-01-27 | 2022-10-04 | 도레이첨단소재 주식회사 | Conductive adheisive composition and electromagnetic wave shielding film comprising the same |
Also Published As
| Publication number | Publication date |
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| WO2017111254A1 (en) | 2017-06-29 |
| KR20170073996A (en) | 2017-06-29 |
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