CN114762470A - Electromagnetic wave shielding film - Google Patents
Electromagnetic wave shielding film Download PDFInfo
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- CN114762470A CN114762470A CN202180007123.6A CN202180007123A CN114762470A CN 114762470 A CN114762470 A CN 114762470A CN 202180007123 A CN202180007123 A CN 202180007123A CN 114762470 A CN114762470 A CN 114762470A
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- Prior art keywords
- layer
- shielding film
- conductive
- 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
- H05K9/0084—Electromagnetic shielding materials, e.g. EMI, RFI shielding comprising a single continuous metallic layer on an electrically insulating supporting structure, e.g. metal foil, film, plating coating, electro-deposition, vapour-deposition
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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
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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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- 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
- H05K9/00—Screening of apparatus or components against electric or magnetic fields
-
- 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
- H05K1/0218—Reduction of cross-talk, noise or electromagnetic interference by printed shielding conductors, ground planes or power plane
Abstract
Provided is an electromagnetic wave shielding film which has excellent transparency and a low connection resistance value even when a conductive adhesive layer contains a large amount of conductive particles. In the electromagnetic wave shielding film of the present invention, a 1 st insulating layer, a transparent conductive layer, a 2 nd insulating layer and a conductive adhesive layer are laminated in this order, the transparent conductive layer is a metal layer having a thickness of 5 to 100nm and made of gold, silver, copper, palladium, nickel, aluminum or an alloy of the foregoing metals, the thickness of the 2 nd insulating layer is 50 to 1000nm, the conductive adhesive layer contains a binder component and spherical or dendritic conductive particles, and the content ratio of the conductive particles is 1 to 80% by mass with respect to 100% by mass of the conductive adhesive layer.
Description
Technical Field
The present invention relates to an electromagnetic wave shielding film. More particularly, the present invention relates to an electromagnetic wave shielding film used in a printed wiring board.
Background
Printed wiring boards are widely used for electronic devices such as mobile phones, video cameras, and notebook personal computers to incorporate circuits in the devices. It is also used for connection of such a movable portion of the print head to the control portion. In these electronic devices, electromagnetic wave shielding measures are essential, and even printed wiring boards used in the devices are shielded printed wiring boards on which the electromagnetic wave shielding measures are implemented.
In a shielded printed wiring board, an electromagnetic wave shielding film (hereinafter, sometimes simply referred to as "shielding film") is used in order to achieve measures for shielding electromagnetic waves. For example, a shielding film used for bonding to a printed wiring board includes a shielding layer such as a metal layer and a conductive bonding sheet provided on the surface of the shielding layer.
As a shielding film including a conductive bonding sheet, for example, those disclosed in patent documents 1 and 2 are known. The shielding film is used by adhering the exposed surface of the conductive bonding sheet to the surface of the printed wiring board, specifically, to the surface of a cover film provided on the surface of the printed wiring board. The conductive bonding sheet is generally subjected to heat pressing under high temperature and high pressure conditions to bond and laminate with a printed wiring board. The shielding film disposed on the printed wiring board as described above exerts a performance of shielding electromagnetic waves from the outside of the printed wiring board (shielding performance).
Documents of the prior art
Patent literature
patent document 2 japanese patent laid-open No. 2012-28334.
Disclosure of Invention
Technical problem to be solved by the invention
In recent years, a shielding film is sometimes required to have a property of being easily aligned when attached to a printed wiring board. Therefore, the shielding film tends to be required to have transparency. As a method for improving the transparency, for example, a transparent conductive layer having a small layer thickness is used as a conductive layer in a shielding film.
However, in the conventional shielding film, the conductivity is higher as the amount of the conductive particles in the conductive adhesive layer is increased, whereas in the shielding film using the transparent conductive layer, if a large amount of the conductive particles is mixed in the conductive adhesive layer, the electrical connection resistance value is increased and the conductivity is lowered.
In view of the above problems, an object of the present invention is to provide an electromagnetic wave shielding film having excellent transparency and a low electrical connection resistance value even when a large amount of conductive particles are blended in a conductive adhesive layer.
Means for solving the problems
The inventors of the present invention have made a keen study to find out that: an electromagnetic wave shielding film having a specific layer structure is excellent in transparency and low in electrical connection resistance even when a large amount of conductive particles are mixed in a conductive adhesive layer. The present invention has been completed based on this finding.
That is, the present invention provides an electromagnetic wave shielding film in which a 1 st insulating layer, a transparent conductive layer, a 2 nd insulating layer, and a conductive adhesive layer are laminated in this order, the transparent conductive layer is a metal layer having a thickness of 5 to 100nm and made of gold, silver, copper, palladium, nickel, aluminum, or an alloy containing one or more of the foregoing metals, the 2 nd insulating layer has a thickness of 50 to 1000nm, the conductive adhesive layer contains a binder component and spherical or dendritic conductive particles, and the content ratio of the conductive particles is 1 to 80% by mass with respect to 100% by mass of the conductive adhesive layer.
Preferably, the 2 nd insulating layer and the conductive adhesive layer are directly laminated.
Preferably, one surface of the 2 nd insulating layer is directly laminated on the conductive adhesive layer, and the other surface is directly laminated on the transparent conductive layer.
Preferably, the content of the conductive particles is 30 to 80% by mass with respect to 100% by mass of the conductive adhesive layer.
Preferably, the electromagnetic wave shielding film has a total light transmittance of 10% or more in a measurement method according to JIS K7361-1.
In addition, the present invention provides a shielded printed wiring board comprising the electromagnetic wave shielding film.
Effects of the invention
The electromagnetic wave shielding film of the present invention has excellent transparency and a low electrical connection resistance value, regardless of whether a small amount of conductive particles are blended in the conductive adhesive layer or a large amount of conductive particles are blended in the conductive adhesive layer.
Drawings
Fig. 1 is a schematic cross-sectional view of an embodiment of an electromagnetic wave shielding film according to the present invention.
Detailed Description
[ Shielding film ]
The shielding film of the present invention has a layer structure in which a 1 st insulating layer, a transparent conductive layer, a 2 nd insulating layer, and a conductive adhesive layer are laminated in this order.
An embodiment of the shielding film of the present invention will be described below. Fig. 1 is a schematic cross-sectional view of an embodiment of a shielding film of the present invention. The shielding film 1 of the present invention shown in fig. 1 comprises a 1 st insulating layer 11, a transparent conductive layer 12, a 2 nd insulating layer 13, and a conductive adhesive layer 14 in this order.
(insulating layer 1)
In the shielding film of the present invention, the 1 st insulating layer is a transparent substrate that functions as a support for protecting the transparent conductive layer and the transparent conductive layer. Examples of the 1 st insulating layer include a plastic substrate (particularly, a plastic film), a glass plate, and the like. The 1 st insulating layer may be a single layer or a laminate of the same or different types.
Examples of the resin constituting the plastic substrate include: polyolefin resins such as low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, ultra-low-density polyethylene, random copolymer polypropylene, block copolymer polypropylene, homo-polypropylene, polybutene, polymethylpentene, ethylene-vinyl acetate copolymer (EVA), ionomers, ethylene- (meth) acrylic acid copolymers, ethylene- (meth) acrylic acid ester (random, alternating) copolymers, ethylene-butene copolymers, ethylene-hexene copolymers and the like; a polyurethane; polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate, and polybutylene terephthalate (PBT); polycarbonate (PC); polyimide (PI); polyetheretherketone (PEEK); a polyetherimide; polyamides such as aromatic polyamides and wholly aromatic polyamides; polyphenylene sulfide; polysulfone (PS); polyethersulfone (PES); acrylic resins such as polymethyl methacrylate (PMMA); acrylonitrile-butadiene-styrene copolymer (ABS); a fluorocarbon resin; polyvinyl chloride; polyvinylidene chloride; cellulose resins such as cellulose Triacetate (TAC); silicone, and the like. The resin may be used alone or in combination of two or more. Among the above resins, polyester and cellulose resins are preferable, and polyethylene terephthalate and cellulose triacetate are more preferable from the viewpoint of more excellent transparency.
For the purpose of improving close adhesiveness with an adjacent layer such as a transparent conductive layer, holding performance, and the like, the surface of the 1 st insulating layer (particularly, the transparent conductive layer side surface) may be subjected to, for example, the following surface treatment: physical treatments such as corona discharge treatment, plasma treatment, sand blasting treatment, ozone exposure treatment, flame exposure treatment, high-voltage electric shock exposure treatment, ionizing radiation treatment and the like; chemical treatments such as chromic acid treatment; easy bonding treatment using a coating agent (primer), and the like. The surface treatment for improving the close adhesion is preferably applied to the entire surface of the transparent conductive layer side in the 1 st insulating layer.
The thickness of the 1 st insulating layer is not particularly limited, but is preferably 1 to 15 μm, more preferably 3 to 10 μm. If the thickness is 1 μm or more, the shielding film and the protective transparent conductive layer can be supported more sufficiently. If the thickness is 15 μm or less, the transparency and flexibility are excellent, and the cost efficiency is also advantageous. When the 1 st insulating layer has a multilayer structure, the thickness of the 1 st insulating layer is the sum of all layer thicknesses.
(transparent conductive layer)
The transparent conductive layer is an element that functions as a shielding layer in the shielding film of the present invention. The transparent conductive layer may be a single layer or a laminate of the same or different types.
The transparent conductive layer is made of gold, silver, copper, palladium, nickel, aluminum, or an alloy containing one or more of the foregoing metals. The transparent conductive layer has shielding performance and excellent transparency.
Examples of the alloy include silver/copper alloy, silver/zinc alloy, silver/tin alloy, silver/palladium alloy, silver/nickel alloy, silver/aluminum alloy, silver/bismuth alloy, silver/germanium alloy, silver/yttrium alloy, silver/neodymium alloy, silver/scandium alloy, silver/indium alloy, silver/antimony alloy, and silver/gallium alloy. Among the metals, copper and silver are preferable from the viewpoint of more excellent electromagnetic wave shielding performance, and silver/copper alloy is preferable from the viewpoint of suppressing silver from being sulfided by sulfur components or corroded by chlorine contained in sweat or the like at the time of solder reflow or when the shielding film is used under a high-temperature and high-humidity environment.
The thickness of the transparent conductive layer is 5 to 100nm, preferably 10 to 50 nm. By setting the thickness to 5nm or more, the shielding performance can be maintained. When the thickness is 100nm or less, the transparency of the barrier film is excellent. When the transparent conductive layer is a multilayer structure, the thickness of the transparent conductive layer is the sum of all the layer thicknesses. The thickness of the transparent conductive layer can be calculated by measuring the cross section of the transparent conductive layer with a Transmission Electron Microscope (TEM).
The method for forming the transparent conductive layer is not particularly limited, and examples thereof include electrolysis, vapor deposition (e.g., vacuum vapor deposition), sputtering, CVD, Metal Organic (MO), plating, and rolling. Among them, a transparent conductive layer formed by vapor deposition or sputtering is preferable from the viewpoint of ease of production.
(the 2 nd insulating layer)
The 2 nd insulating layer is a transparent layer protecting the transparent conductive layer. By providing the 2 nd insulating layer between the transparent conductive layer and the conductive adhesive layer, it is possible to suppress a decrease in transparency and connection stability. The decrease in transparency and connection stability is presumably caused by damage to the transparent conductive layer due to friction with the conductive particles in the conductive adhesive layer. The 2 nd insulating layer may be a single layer or a plurality of layers.
The 2 nd insulating layer preferably contains a binder component. Examples of the binder component include thermoplastic resins, thermosetting resins, and active energy ray-curable compounds. The thermoplastic resin, the thermosetting resin, and the active energy ray-curable compound are exemplified as binder components that can be contained in the conductive adhesive layer described later. The binder component may be used alone or in combination of two or more.
The content of the binder component in the 2 nd insulating layer is not particularly limited, but is preferably 70 mass% or more, more preferably 80 mass% or more, and still more preferably 90 mass% or more with respect to 100 mass% of the 2 nd insulating layer. If the content is 70 mass% or more, flexibility is more excellent, insertion property into a small-diameter hole is excellent, and connection stability is more excellent.
The 2 nd insulating layer may contain other components than the above binder component within a range not to impair the effects of the present invention. Examples of the other components include a curing agent, a curing accelerator, a plasticizer, a flame retardant, an antifoaming agent, a viscosity adjuster, an antioxidant, a diluent, an anti-settling agent, a filler, a leveling agent, a coupling agent, an ultraviolet absorber, a tackifying resin, and an anti-blocking agent. The other components may be used alone or in combination of two or more.
The thickness of the 2 nd insulating layer is 50 to 1000nm, preferably 100 to 300 nm. By making the thickness more than 50nm, the shielding performance and the connection stability are superior. By setting the thickness to 1000nm or less, the transparency and the connection stability are excellent. When the 2 nd insulating layer is a multi-layer structure, the thickness of the 2 nd insulating layer is the sum of all the layer thicknesses.
From the viewpoint of protecting the transparent conductive layer, the 2 nd insulating layer is preferably directly laminated with the conductive adhesive layer, and particularly preferably directly laminated with the conductive adhesive layer on one surface and directly laminated with the transparent conductive layer on the other surface.
(conductive adhesive layer)
The conductive adhesive layer has, for example, bondability for bonding the shielding film of the present invention to a printed wiring board, and conductivity for electrically connecting the transparent conductive layer. The conductive adhesive layer functions as a shielding layer that exhibits shielding performance together with the transparent conductive layer. The conductive adhesive layer may be a single layer or a plurality of layers.
The conductive adhesive layer contains a binder component and spherical or dendritic (dendritic) conductive particles.
Examples of the binder component include thermoplastic resins, thermosetting resins, and active energy ray-curable compounds. The binder component may be used alone or in combination of two or more.
Examples of the thermoplastic resin include polystyrene resin, vinyl acetate resin, polyester resin, polyolefin resin (e.g., polyethylene resin, polypropylene resin composition, etc.), polyimide resin, and acrylic resin. The thermoplastic resin may be used alone or in combination of two or more.
Examples of the thermosetting resin include both a resin having thermosetting properties (thermosetting resin) and a resin obtained by curing the thermosetting resin. Examples of the thermosetting resin include phenol resins, epoxy resins, polyurethane urea resins, melamine resins, alkyd resins, and the like. The thermosetting resin may be used alone or in combination of two or more.
Examples of the epoxy resin include a bisphenol epoxy resin, a spiro (spiro) epoxy resin, a naphthalene epoxy resin, a biphenyl epoxy resin, a terpene epoxy resin, a glycidyl ether epoxy resin, a glycidyl amine epoxy resin, and a (phenol) novolac epoxy resin.
Examples of the bisphenol epoxy resin include bisphenol a epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, tetrabromobisphenol a epoxy resin, and the like. Examples of the glycidyl ether type epoxy resin include tris (glycidyl ether oxyphenyl) methane and tetrakis (glycidyl ether oxyphenyl) ethane. Examples of the glycidyl amine type epoxy resin include tetraglycidyl diaminodiphenylmethane and the like. Examples of the (novolak) type epoxy resin include cresol (novolak) type epoxy resin, phenol (novolak) type epoxy resin, α -naphthol (novolak) type epoxy resin, and brominated phenol (novolak) type epoxy resin.
Examples of the active energy ray-curable compound include both a compound curable by irradiation with an active energy ray (active energy ray-curable compound) and a compound obtained by curing the active energy ray-curable compound. The active energy ray-curable compound is not particularly limited, and examples thereof include polymerizable compounds having at least 2 radically reactive groups (e.g., (meth) acryloyl groups) in the molecule. The active energy ray-curable compound may be used alone, or two or more kinds thereof may be used.
Among them, the binder component is preferably a thermosetting resin. In this case, after the shielding film of the present invention is disposed on a printed wiring board for bonding to the printed wiring board, the adhesive component can be cured by applying pressure and heat, and the bonding property to the printed wiring board is good.
When the binder component contains a thermoplastic resin, a monomer component of the thermoplastic resin may be contained as a component constituting the binder component. By including a monomer component as the binder component, the adhesive composition is excellent in temporary adhesiveness, reworkability, and close adhesiveness after hot pressing to an object to be bonded.
When the binder component contains a thermosetting resin, a curing agent for promoting a thermosetting reaction may be contained as a component constituting the binder component. The curing agent can be appropriately selected according to the kind of the thermosetting resin. The curing agent may be used alone or in combination of two or more.
The content of the binder component in the conductive adhesive layer is not particularly limited, and is preferably 20 to 99 mass%, more preferably 30 to 80 mass%, and still more preferably 40 to 70 mass% with respect to 100 mass% of the total amount of the conductive adhesive layer. If the content ratio is 20% by mass or more, the close adhesion to the printed wiring board is more excellent. If the content ratio is 99% by mass or less, the conductive particles can be sufficiently contained.
Spherical conductive particles and/or dendritic conductive particles are used as the conductive particles. By using the spherical or dendritic conductive particles, the transparency and the connection stability are excellent even when a large amount of the particles are mixed. When spherical conductive particles are used, the transparency is more excellent.
Examples of the conductive particles include metal particles, metal-coated resin particles, and carbon-based fillers. The conductive particles may be used alone or in combination of two or more.
Examples of the metal constituting the coating portion of the metal particles and the metal-coated resin particles include gold, silver, copper, nickel, and zinc. The metal may be used alone or in combination of two or more.
Specifically, examples of the metal particles include copper particles, silver particles, nickel particles, silver-coated copper particles, gold-coated copper particles, silver-coated nickel particles, gold-coated nickel particles, and silver-coated alloy particles. Examples of the silver-coated alloy particles include silver-coated copper alloy particles formed by coating copper alloy particles (for example, copper alloy particles formed of an alloy of copper, nickel, and zinc) with silver. The metal particles can be produced by an electrolytic method, an atomization method, a reduction method, or the like.
Among them, the metal particles are preferably silver particles, silver-coated copper particles, or silver-coated copper alloy particles. Silver-coated copper particles and silver-coated copper alloy particles are particularly preferable from the viewpoint of being excellent in conductivity, suppressing oxidation and coagulation of metal particles, and reducing the cost of metal particles.
The median diameter (D50) of the conductive particles is not particularly limited, but is preferably 5 to 15 μm, more preferably 5 to 10 μm. The median diameter is a median diameter of all spherical conductive particles and/or dendritic conductive particles in the conductive adhesive layer, and refers to a particle diameter at a cumulative value of 50% in a particle size distribution obtained by laser diffraction/seed scattering method. By making the median diameter within the above range, the connection stability of the present invention using the conductive particles is more excellent. The median diameter can be measured, for example, by a laser diffraction particle size analyzer (trade name "SALD-2200", manufactured by Shimadzu corporation).
In the conductive adhesive layer, the content of the conductive particles is 1 to 80% by mass, preferably 20 to 70% by mass, and more preferably 30 to 60% by mass, relative to 100% by mass of the conductive adhesive layer. In the shielding film of the present invention, the conductive adhesive layer has a low connection resistance value and excellent connection stability regardless of whether the conductive adhesive layer contains a small amount of the conductive particles of about 1 mass% or contains a large amount of the conductive particles of up to 80 mass%.
The conductive adhesive layer may contain other components than the above components within a range not to impair the effects of the present invention. The other components include those contained in a known or commonly used adhesive layer. Examples of the other components include a curing accelerator, a plasticizer, a flame retardant, an antifoaming agent, a viscosity modifier, an antioxidant, a diluent, an anti-settling agent, a filler, a leveling agent, a coupling agent, an ultraviolet absorber, a colorant, and an anti-blocking agent. The other components may be used alone or in combination of two or more. On the other hand, the content of the conductive particles other than the spherical conductive particles and the dendritic conductive particles is, for example, less than 10 parts by mass, preferably less than 5 parts by mass, and more preferably less than 1 part by mass, relative to 100 parts by mass of the spherical conductive particles and/or the dendritic conductive particles.
The thickness of the conductive adhesive layer is not particularly limited, but is preferably 3 to 20 μm, and more preferably 5 to 15 μm. If the thickness is 3 μm or more, the shielding performance is more excellent. If the thickness is 20 μm or less, the surface of the conductive particle tends to be closer to the surface of the layer or exposed from the surface, and the connection stability is more excellent.
The ratio [ adhesive layer thickness/D50 ] of the thickness of the conductive adhesive layer to the D50 of the conductive particles is not particularly limited, but is preferably 0.2 to 1.5, more preferably 0.5 to 1.0. If the ratio is 0.2 or more, the bondability to the object to be bonded such as a printed wiring board is further improved. If the ratio is 1.5 or less, the amount of conductive particles exposed from the surface of the conductive adhesive layer is large, and the connection stability is more excellent.
The shielding film of the present invention may contain a separator (release film) on the conductive adhesive layer side. The separator is laminated so as to be peelable from the shielding film of the present invention. The separator is an element for covering and protecting the conductive adhesive layer and is peeled off when the shielding film of the present invention is used.
Examples of the separator include a polyethylene terephthalate (PET) film, a polyethylene film, a polypropylene film, and a plastic film or paper coated with a release agent such as a fluorine-based release agent or a long-chain alkyl acrylate-based release agent.
The thickness of the separator is preferably 10 to 200 μm, and more preferably 15 to 150 μm. If the thickness is 10 μm or more, the protective properties are more excellent. If the thickness is 200 μm or less, the separator is easily peeled off in use.
The shielding film of the present invention may contain other layers than the 1 st insulating layer, the transparent conductive layer, the 2 nd insulating layer and the conductive adhesive layer. Examples of the other layer include other insulating layers, antireflection layers, antiglare layers, antifouling layers, hard coat layers, ultraviolet absorbing layers, and newton ring prevention layers.
The shielding film of the present invention is superior in transparency. The total light transmittance of the barrier film of the present invention is preferably 10% or more, more preferably 20% or more, further preferably 50% or more, and particularly preferably 65% or more in the measurement method according to JIS K7361-1. The total light transmittance can be measured using a known spectrophotometer. The total light transmittance was measured for a laminate having the 1 st insulating layer and the conductive adhesive layer as both end layers.
The haze value of the barrier film of the present invention is preferably 95% or less, more preferably 92% or less, and further preferably 90% or less in the measurement method according to JIS K7361-1. The haze value can be measured using a well-known spectrophotometer. The haze value was measured for a laminate having the 1 st insulating layer and the conductive adhesive layer as both end layers.
The shielding film of the present invention is preferably used for a printed wiring board or for a wireless power transmission system, and particularly preferably used for a flexible printed wiring board (FPC) or for an electromagnetic induction type wireless power transmission system. The shielding film of the present invention has a low electrical connection resistance value regardless of whether a small amount of conductive particles are mixed in the conductive adhesive layer or a large amount of conductive particles are mixed in the conductive adhesive layer. The shielding film of the present invention is excellent in transparency and can be easily aligned with an object to be bonded, such as a printed wiring board or a power supply or power transmission coil in a wireless power transmission system. Therefore, the shielding film of the present invention is preferably used as an electromagnetic wave shielding film for a flexible printed wiring board.
(method for producing electromagnetic wave shielding film)
The method for producing the shielding film of the present invention is explained below.
In the production of the shielding film 1 of the present invention shown in fig. 1, a transparent conductive layer 12 is first formed on a 1 st insulating layer 11. The transparent conductive layer 12 is preferably formed by an evaporation method or a sputtering method. The vapor deposition method and the sputtering method can be any known or conventional methods. In this manner, the transparent conductive layer is formed by the vapor deposition method or the sputtering method, whereby a conductive layer having an appropriate thickness and transparency can be easily produced.
Next, the surface of the formed transparent conductive layer 12 can be coated with (coated with) a resin composition for forming the 2 nd insulating layer 13, and the 2 nd insulating layer 13 can be formed by removing a solvent and/or partially curing, if necessary.
For example, the resin composition may further include a solvent (solvent) in addition to the components contained in the 2 nd insulating layer. Examples of the solvent include toluene, acetone, methyl ethyl ketone, methanol, ethanol, propanol, ethyl acetate, propyl acetate, butyl acetate, and dimethylformamide. The solid content concentration of the resin composition is appropriately set according to the thickness of the 2 nd insulating layer to be formed, and the like.
The resin composition can be applied by a known coating method. For example, a gravure roll coater, a reverse roll coater, an oil feed roll coater, a lip coater, a dip roll coater, a bar coater, a knife coater, a spray coater, a comma coater, a direct coater, a slit coater, or the like can be used.
Next, an adhesive composition for forming the conductive adhesive layer 14 is applied (coated) on the surface of the formed insulating layer 2, and the conductive adhesive layer 14 can be formed by removing a solvent and/or partially curing the composition as necessary.
For example, the adhesive composition may contain a solvent (solvent) in addition to the components contained in the conductive adhesive layer. The solvent is exemplified as the solvent that the resin composition may contain. The solid content concentration of the adhesive composition is appropriately set according to the thickness of the conductive adhesive layer to be formed, and the like.
The adhesive composition can be applied by a known coating method. Examples of the coating machine used for coating the resin composition include those exemplified above.
In the above-described manufacturing method, a method (direct coating method) of forming each layer in sequence has been described, but the present invention is not limited to the above-described method, and may be formed by a method (lamination method) of laminating and sequentially bonding each layer formed separately on a temporary substrate such as a release film or a substrate.
The shielding film of the present invention can be used to manufacture a printed wiring board. For example, a shielded printed wiring board in which the shielding film of the present invention is bonded to a printed wiring board can be obtained by bonding the conductive adhesive layer of the shielding film of the present invention to a printed wiring board (for example, a cover film). In the shielded printed wiring board, the conductive adhesive layer may be thermally cured.
Examples
The present invention will be described in further detail below based on examples, but the present invention is not limited to these examples. The conductive particle content in the table indicates the content in the conductive adhesive layer.
Comparative example 1
A silver/copper alloy layer (thickness: 10 nm) was formed on the surface of a PET film (thickness: 6 μm) by sputtering. Then, an adhesive composition obtained by mixing and mixing an epoxy resin solution and conductive particles a (silver-coated copper powder, spherical, 5 μm median diameter) was applied to the surface of the alloy layer using a wire bar, and the mixture was heated at 120 ℃ for 1 minute to form a conductive adhesive layer (5 μm thickness). The shielding film of comparative example 1 was produced as described above. The amount of the epoxy resin solution and the conductive particles a mixed is such that the ratio of the epoxy resin in the conductive adhesive layer is 70 mass% and the ratio of the conductive particles a is 30 mass%.
Comparative examples 2 to 4
Each barrier film was produced in the same manner as in comparative example 1, except that the kind and content ratio of the conductive particles were changed as shown in table 1. The conductive particles B were silver-coated copper powder (dendritic, median diameter 5 μm).
Example 1
A silver/copper alloy layer (thickness 10 nm) was formed on the surface of the PET film (thickness 6 μm) by sputtering. Subsequently, a polyester resin composition was applied to the surface of the alloy layer using a wire bar, and the resultant was heated at 100 ℃ for 1 minute to form a resin layer (thickness 50 nm). Then, an adhesive composition obtained by mixing an epoxy resin solution and conductive particles a was applied to the surface of the above resin layer using a wire bar, and heated at 120 ℃ for 1 minute to form a conductive adhesive layer (thickness 5 μm). The shielding film of example 1 was produced as above. The amount of the epoxy resin solution and the conductive particles a mixed is such that the ratio of the epoxy resin in the conductive adhesive layer is 70 mass% and the ratio of the conductive particles a is 30 mass%.
Examples 2 to 4 and comparative examples 5 and 6
Each of the shielding films was produced in the same manner as in example 1, except that the thickness of the resin layer was changed as shown in table 1.
Example 5
A shielding film was produced in the same manner as in example 1, except that the content ratio of the conductive particles was changed as shown in table 1.
Examples 6 to 8 and comparative examples 7 and 8
Each of the shielding films was produced in the same manner as in example 5, except that the thickness of the resin layer was changed as shown in table 1.
Example 9
A shielding film was produced in the same manner as in example 1, except that the kind of the conductive particles was changed as shown in table 1.
Examples 10 to 12 and comparative examples 9 and 10
Each of the shielding films was produced in the same manner as in example 9, except that the thickness of the resin layer was changed as shown in table 1.
(evaluation)
Each of the shielding films obtained in examples and comparative examples was evaluated as follows. The evaluation results are set forth in the table. Only a PET film (thickness: 6 μm) was used as an evaluation object in reference example 1. Further, "OL" in the table indicates a value exceeding the measurement limit of 100 Ω due to overload.
(1) Connection resistance value
Preparing the following printed circuit base materials: on a base member made of a polyimide film, 2 copper foil patterns (width 4mm, pitch 1 mm) similar to a ground pattern were formed, and a cover film (insulating film) made of an insulating adhesive layer and a polyimide film was formed thereon. And a gold plating layer is arranged on the surface of the copper foil pattern to be used as a surface layer. And a circular opening portion simulating a ground connection portion having a diameter of 0.8mm is formed in the cover film. The shielding films and the printed wiring substrates fabricated in the respective examples and comparative examples were bonded to each other by using a press under conditions of a temperature of 170 ℃, a time of 30 minutes, and a pressure of 2 to 3 MPa. After the shield film was bonded, the resistance value between 2 copper foil patterns was measured by a resistance meter, and the connectivity between the copper foil patterns and the conductive bonding sheet was evaluated as a connection resistance value.
(2) Total light transmittance
The shielding films obtained in examples and comparative examples were measured by irradiating the surface of a PET film with measuring light on the integrating sphere side in accordance with JIS K7361-1 using a haze meter apparatus (trade name "NDH 4000", manufactured by japan electro-color industries, ltd.).
When a silver/copper alloy layer having a thickness of 10nm is used as the transparent conductive layer, the barrier film of the present invention can provide a high total light transmittance, excellent transparency, a low connection resistance value, and excellent connection stability even when a large amount of conductive particles is contained as much as 30 to 50 mass% (examples 1 to 12). In addition, compared with the use of dendritic conductive particles (examples 9 to 12), in the use of spherical conductive particles (examples 1 to 4) in the total light transmittance high, transparency tendency. On the other hand, as shown by the results, when no resin layer is present between the silver/copper alloy layer and the conductive adhesive layer (comparative examples 1 to 4), the connection resistance value was high under a large amount of 30 mass% or more. On the other hand, when the thickness of the resin layer is 2000nm or more, the connection resistance value is high (comparative examples 5 to 10).
Description of the numbering
1 Shielding film
11 st insulating layer
12 transparent conductive layer
13 nd 2 nd insulating layer
14 conductive adhesive layer
Claims (6)
1. An electromagnetic wave shielding film, characterized in that:
in the electromagnetic wave shielding film, a 1 st insulating layer, a transparent conductive layer, a 2 nd insulating layer, and a conductive adhesive layer are laminated in this order;
the transparent conducting layer is a metal layer which is composed of gold, silver, copper, palladium, nickel, aluminum or an alloy containing more than one of the metals and has the thickness of 5-100 nm;
the thickness of the 2 nd insulating layer is 50-1000 nm;
the conductive adhesive layer contains a binder component and spherical or dendritic conductive particles;
the content ratio of the conductive particles is 1-80% by mass relative to 100% by mass of the conductive adhesive layer.
2. The electromagnetic wave shielding film according to claim 1, characterized in that:
the 2 nd insulating layer and the conductive adhesive layer are directly laminated.
3. The electromagnetic wave shielding film according to claim 1, characterized in that:
one surface of the 2 nd insulating layer is directly laminated on the conductive adhesive layer, and the other surface is directly laminated on the transparent conductive layer.
4. The electromagnetic wave shielding film according to any one of claims 1 to 3, characterized in that:
The content ratio of the conductive particles is 30-80% by mass relative to 100% by mass of the conductive adhesive layer.
5. The electromagnetic wave shielding film according to any one of claims 1 to 4, characterized in that:
the electromagnetic wave shielding film has a total light transmittance of 10% or more in a measurement method according to JIS K7361-1.
6. A shielded printed wiring board characterized in that:
the shielding printed wiring board includes the electromagnetic wave shielding film of any one of claims 1 to 5.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2020000637 | 2020-01-07 | ||
| JP2020-000637 | 2020-01-07 | ||
| PCT/JP2021/000263 WO2021141067A1 (en) | 2020-01-07 | 2021-01-07 | Electromagnetic wave shielding film |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114762470A true CN114762470A (en) | 2022-07-15 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202180007123.6A Pending CN114762470A (en) | 2020-01-07 | 2021-01-07 | Electromagnetic wave shielding film |
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| Country | Link |
|---|---|
| JP (1) | JP6956926B1 (en) |
| KR (1) | KR20220124684A (en) |
| CN (1) | CN114762470A (en) |
| TW (1) | TWI807242B (en) |
| WO (1) | WO2021141067A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| KR102594352B1 (en) * | 2022-10-13 | 2023-10-26 | 주식회사 유라 | High-speed communication cable for autovehicles with improved electromagnetic wave shielding performance and manufacturing method thereof |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02271697A (en) * | 1989-04-13 | 1990-11-06 | Nitto Denko Corp | Electrostatic and electromagnetic wave shielding material |
| JP2001185894A (en) * | 1999-10-12 | 2001-07-06 | Bridgestone Corp | Electromagnetic wave-shield glass |
| JP4491929B2 (en) * | 2000-07-27 | 2010-06-30 | 株式会社ブリヂストン | Electromagnetic wave shielding light transmissive laminate, method for producing the same, and method for mounting the same |
| JP2002246788A (en) * | 2000-12-12 | 2002-08-30 | Nisshinbo Ind Inc | Transparent electromagnetic radiation shielding material |
| JP2005183652A (en) * | 2003-12-19 | 2005-07-07 | Fuji Photo Film Co Ltd | Electromagnetic wave shielding material and its manufacturing method, and display |
| JP5672201B2 (en) | 2011-09-07 | 2015-02-18 | デクセリアルズ株式会社 | Anisotropic conductive film and method for manufacturing connection structure |
| WO2015068611A1 (en) | 2013-11-07 | 2015-05-14 | 東洋インキＳｃホールディングス株式会社 | Electroconductive adhesive, electroconductive adhesive sheet, wiring device, and method for manufacturing wiring device |
| JP6512804B2 (en) * | 2014-12-05 | 2019-05-15 | 日東電工株式会社 | Transparent conductive film laminate and use thereof |
| JP6516108B2 (en) * | 2017-08-10 | 2019-05-22 | 東洋インキＳｃホールディングス株式会社 | Electromagnetic wave shield laminate for vacuum forming, and electromagnetic wave shield molded body using the same |
| JP6863908B2 (en) * | 2018-01-12 | 2021-04-21 | タツタ電線株式会社 | Electromagnetic wave shield film |
-
2021
- 2021-01-07 CN CN202180007123.6A patent/CN114762470A/en active Pending
- 2021-01-07 WO PCT/JP2021/000263 patent/WO2021141067A1/en active Application Filing
- 2021-01-07 KR KR1020227019747A patent/KR20220124684A/en not_active Application Discontinuation
- 2021-01-07 JP JP2021522110A patent/JP6956926B1/en active Active
- 2021-01-07 TW TW110100652A patent/TWI807242B/en active
Also Published As
| Publication number | Publication date |
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| JPWO2021141067A1 (en) | 2021-07-15 |
| TW202134051A (en) | 2021-09-16 |
| KR20220124684A (en) | 2022-09-14 |
| JP6956926B1 (en) | 2021-11-02 |
| TWI807242B (en) | 2023-07-01 |
| WO2021141067A1 (en) | 2021-07-15 |
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