WO2018021623A1 - Feuille complexe pour charge sans fil et procédé de fabrication de celle-ci - Google Patents

Feuille complexe pour charge sans fil et procédé de fabrication de celle-ci Download PDF

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Publication number
WO2018021623A1
WO2018021623A1 PCT/KR2016/013187 KR2016013187W WO2018021623A1 WO 2018021623 A1 WO2018021623 A1 WO 2018021623A1 KR 2016013187 W KR2016013187 W KR 2016013187W WO 2018021623 A1 WO2018021623 A1 WO 2018021623A1
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electromagnetic wave
parts
wave shielding
layer
complex sheet
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PCT/KR2016/013187
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English (en)
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Sang Seok Park
Doo Hyeon Kim
Jung Il Park
Eun Kwang Hur
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Innox Advanced Materials Co., Ltd.
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Publication of WO2018021623A1 publication Critical patent/WO2018021623A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
    • H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
    • H01F1/20—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of particles, e.g. powder
    • H01F1/22—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together
    • H01F1/24—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together the particles being insulated
    • H01F1/26—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together the particles being insulated by macromolecular organic substances
    • 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
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
    • C09J11/02—Non-macromolecular additives
    • C09J11/04—Non-macromolecular additives inorganic
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
    • C09J11/02—Non-macromolecular additives
    • C09J11/06—Non-macromolecular additives organic
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
    • C09J11/08—Macromolecular additives
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J163/00—Adhesives based on epoxy resins; Adhesives based on derivatives of epoxy resins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
    • H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
    • H01F1/147—Alloys characterised by their composition
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
    • H01F1/34—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials non-metallic substances, e.g. ferrites
    • H01F1/36—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials non-metallic substances, e.g. ferrites in the form of particles
    • H01F1/37—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials non-metallic substances, e.g. ferrites in the form of particles in a bonding agent
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/34—Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
    • H01F27/36—Electric or magnetic shields or screens
    • H01F27/366—Electric or magnetic shields or screens made of ferromagnetic material
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
    • H02J50/70—Circuit arrangements or systems for wireless supply or distribution of electric power involving the reduction of electric, magnetic or electromagnetic leakage fields
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
    • H02J50/10—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling

Definitions

  • Embodiments of the present invention relate to a wireless charging technique.
  • the battery is charged using transmission of electromagnetic wave over air, such that the electromagnetic wave is principally harmful to a human body and affects other electronic parts, which in turn, needs to be shielded. Further, heat is generated in a wireless charging module during wireless charging, and therefore, it is necessary to rapidly transmit the generated heat to an outside to protect damage of the electronic parts caused by the heat.
  • an electromagnetic wave shielding sheet some commercially available products made of diverse materials have been widely used. However, such conventional electromagnetic wave shielding sheets have low thermal conductivity and could not obtain sufficient heat radiation effect. Accordingly, it is required that heat radiation effect and electromagnetic wave shielding effect are preferably and simultaneously achieved.
  • Patent Document 1 Korean Patent Laid-Open Publication No. 10-2016-0043294 (2016. 04. 21)
  • Embodiments of the present invention provide a complex sheet for wireless charging able to achieve electromagnetic wave shielding effect and heat radiation effect, simultaneously, and a method for fabricating the same.
  • a complex sheet for wireless charging including: an electromagnetic wave shielding layer configured to shield electromagnetic wave generated in a wireless charging coil; and a graphite layer which is adhered to the electromagnetic wave shielding layer by the electromagnetic wave shielding layer, and includes a plurality of through holes formed therein, wherein at least a portion inside of the through hole is filled with an adhesive component derived from the electromagnetic wave shielding layer.
  • the electromagnetic wave shielding layer may be made of a cured product of a resin mixture including a thermosetting epoxy resin, a rubber binder, a silane coupling agent, a fluorine surfactant, soft magnetic powders, a hardener and a moisture-proof agent.
  • the resin mixture may include 160 to 350 parts by weight of the rubber binder, 4 to 25 parts by weight of the silane coupling agent, 0.5 to 5 parts by weight of the fluorine surfactant, 700 to 1,500 parts by weight of the soft magnetic powders, 2 to 30 parts by weight of the hardener and 1 to 25 parts by weight of the moisture-proof agent to 100 parts by weight of the thermosetting epoxy resin.
  • the soft magnetic powder may include at least one selected from an Fe-Si-Al alloy, Fe-Si-Cr alloy, Fe-Si-B alloy, highflux, permalloy alloy, Ni-Zn ferrite alloy and Mn-Zn ferrite alloy.
  • the soft magnetic powder may have a mean particle diameter of 20 ⁇ m to 100 ⁇ m,
  • the electromagnetic wave shielding layer may be laminated on the graphite layer, and the through hole may be formed to perforate from one surface of the graphite layer facing the electromagnetic wave shielding layer to the other surface of the graphite layer.
  • the through hole may have a degree of transformation satisfying Equation 1 below:
  • the through hole may have a cross-section formed in a circular shape, and has a mean diameter of 0.5 mm to 8 mm.
  • An entire area of the through holes may range from 2% to 30% to an entire area of one surface or the other surface of the graphite layer.
  • a complex sheet for wireless charging including: an electromagnetic wave shielding layer configured to shield electromagnetic wave generated in a wireless charging coil; a graphite layer including a plurality of through holes formed therein; and an adhesive layer disposed between the electromagnetic wave shielding layer and the graphite layer to adhere the electromagnetic wave shielding layer and the graphite layer together with each other, wherein at least a portion inside of the through hole is filled with an adhesive component derived from the adhesive layer.
  • the electromagnetic wave shielding layer, the adhesive layer and the graphite layer may be laminated in this order from one surface to the other surface of the complex sheet for wireless charging, and the through hole may be formed to perforate from one surface of the graphite layer facing the adhesive layer to the other surface of the graphite layer.
  • the adhesive layer may include a thermosetting resin, a rubber binder, a silane coupling agent, a fluorine surfactant, a hardener, a curing enhancer, a flame retardant and a moisture-proof agent, in a range of: 25 to 100 parts by weight of the rubber binder, 1 to 10 parts by weight of the silane coupling agent, 0.01 to 2 parts by weight of the fluorine surfactant, 5 to 20 parts by weight of the hardener, 1 to 5 parts by weight of the curing enhancer, 30 to 60 parts by weight of the flame retardant, and 0.5 to 10 parts by weight of the moisture-proof agent to 100 parts by weight of the thermosetting epoxy resin.
  • the adhesive layer may further include thermoconductive filler containing at least one selected from graphite powders, carbon nanotube (CNT), carbon black powders, carbon fiber, ceramic powders and metal powders.
  • thermoconductive filler containing at least one selected from graphite powders, carbon nanotube (CNT), carbon black powders, carbon fiber, ceramic powders and metal powders.
  • the through hole may have a degree of transformation satisfying Equation 1 below:
  • An entire area of the through holes may range from 2% to 30% to an entire area of one surface or the other surface of the graphite layer.
  • a method of preparing a complex sheet for wireless charging including: introducing a laminate, in which an electromagnetic wave shielding layer and a graphite layer including a plurality of through holes are laminated, into a hot press machine; heating and pressing the laminate at 145°C to 160°C and under a pressure of 45 to 60 kgf/cm 2 to conduct a hot-pressing process; and cooling the hot press and separating the laminate from the hot press.
  • a method of preparing a complex sheet for wireless charging including: introducing a laminate in which an electromagnetic wave shielding layer, an adhesive layer and a graphite layer including a plurality of through holes are laminated, into a hot press machine; heating and pressing the laminate at 145°C to 160°C and under a pressure of 45 to 60 kgf/cm 2 to conduct a hot-pressing process; and cooling the hot press and separating the laminate from the hot press.
  • the electromagnetic wave shielding layer may be combined with the graphite layer by an adhesive component derived from the electromagnetic wave shielding layer, so as to reduce a thickness of a complex sheet for wireless charging 100 and thus form a thin film type complex sheet for wireless charging.
  • an adhesive component derived from the electromagnetic wave shielding layer since the electromagnetic wave shielding layer and the graphite layer are directly adhered to each other, heat transfer performance from the electromagnetic wave shielding layer to the graphite layer may be improved.
  • a vertical thermal conductivity of the graphite layer may be minimized while maximizing a horizontal thermal conductivity, thereby enhancing heat radiation performance of the graphite layer.
  • a peel-off strength between the electromagnetic wave shielding layer and the graphite layer and an interlayer peel-off strength in the graphite layer may be increased, so that impact resistance and durability of the complex sheet for wireless charging may be improved.
  • FIG. 1 is a cross-sectional view illustrating a configuration of a complex sheet for wireless charging according to an exemplary embodiment.
  • FIG. 2 is views illustrating a cross-section of through holes in a graphite layer of the complex sheet for wireless charging according to the exemplary embodiment.
  • FIG. 3 is a flow chart illustrating a method of preparing a complex sheet for wireless charging according to the exemplary embodiment.
  • FIG. 4 is a cross-sectional view illustrating a configuration of a complex sheet for wireless charging according to another exemplary embodiment.
  • FIG. 1 is a cross-sectional view illustrating a configuration of a complex sheet for wireless charging according to an exemplary embodiment of the present invention.
  • a complex sheet for wireless charging 100 may include an electromagnetic wave shielding layer 102 and a graphite layer 104.
  • a coil 50 may be formed on the electromagnetic wave shielding layer 102.
  • the coil 50 may sever to transmit a wireless power, and may serve to receive the wireless power. That is, the complex sheet for wireless charging 100 may be used in a device for wireless power transmission or in another device for wireless power reception.
  • the graphite layer 104 may include a plurality of through holes 104a formed therein. The through holes 104a may be filled with an adhesive component derived from the electromagnetic wave shielding layer 102, which will be described in detail below.
  • the electromagnetic wave shielding layer 102 may shield electromagnetic wave generated in the coil 50.
  • the coil 50 may be formed on one surface of the electromagnetic wave shielding layer 102.
  • the electromagnetic wave shielding layer 102 may serve to shield the electromagnetic wave, as well as, absorb the electromagnetic wave.
  • the electromagnetic wave shielding layer 102 may be made of a cured product of a resin mixture including, for example, a thermosetting epoxy resin, a rubber binder, a silane coupling agent, a fluorine surfactant, soft magnetic powders, a hardener (curing agent) and a curing enhancer.
  • the electromagnetic wave shielding layer 102 may be a metal sheet.
  • the adhesive component in the electromagnetic wave shielding layer 102 may be partially molten and filled in the through holes 104a of the graphite layer 106.
  • the electromagnetic wave shielding layer 102 and the resin mixture forming the same may have the same as or lower melting point than a hot-press processing temperature (145°C-160°C), and preferably, it is advantageous to more or less lower melting point.
  • the thermosetting epoxy resin may include at least one selected from a bisphenol A epoxy resin, bisphenol F epoxy resin, novolac epoxy resin, Br containing epoxy resin, etc., which may be used alone or in combination with two or more thereof.
  • the rubber binder may include at least one selected from acryl rubber, silicone rubber, carboxylated nitrile elastomer and phenoxy, and preferably, at least one alone or two or more of acryl rubber and silicone rubber.
  • the rubber binder used therein may be carboxylic elastomer, and preferably, carboxylated nitrile elastomer.
  • the carboxylic elastomer used herein has a weight average molecular weight of 180,000 to 350,000, preferably, 210,000 to 280,000, and more preferably, 215,000 to 255,000, in terms of securing bending resistance and heat resistance of the complex sheet for wireless charging 100.
  • An amount of the rubber binder used in the resin mixture may range from 160 to 360 parts by weight ('wt. parts') to 100 wt. parts of thermosetting epoxy resin. The reason is that: if the used amount of the rubber binder is less than 160 wt. parts to 100 wt. parts of thermosetting epoxy resin, the electromagnetic wave shielding layer 102 has reduced flexibility, and thus, when the complex sheet for wireless charging 100 is bent, a bonded portion between the electromagnetic wave shielding layer 102 and the graphite layer 104 may be partially peeled-off; and, if the used amount of the rubber binder exceeds 350 wt. parts to 100 wt.
  • thermosetting epoxy resin it is economically disadvantageous and amounts of other components may be relatively reduced, hence deteriorating electromagnetic wave shielding performance of the electromagnetic wave shielding layer 102 and adhesiveness to the graphite layer 104.
  • the used amount of the rubber binder preferably ranges from 180 to 300 wt. parts, and more preferably, ranges from 200 to 280 wt. parts to 100 wt. parts of thermosetting epoxy resin.
  • the silane coupling agent among the components of the resin mixture plays a role of dispersing particles, which may include any typical silane coupling agent used in the related art.
  • at least one selected from glycidoxy(C2-C5 alkyl)trialkoxysilane, vinyltri(C2-C5 alkoxy)silane and aminoethyl aminopropyl silanetriol is used.
  • one selected from glycidoxyethyl trimethoxysilane, glycidoxypropyl trimethoxysilane, glycidoxypropyl ethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane and aminoethyl aminopropyl silanetriol may be used alone or in combination with two or more thereof.
  • an amount of the silane coupling agent used may range from 4 to 25 wt. parts to 100 wt. parts of thermosetting epoxy resin. The reason is that: if the used amount of the silane coupling agent is less than 4 wt. parts to 100 wt.
  • thermosetting epoxy resin the used amount is too small to obtain effects of dispersing particles of the component in the resin mixture; and, if the used amount of the coupling agent exceeds 25 wt. parts to 100 wt. parts of thermosetting epoxy resin, particle agglomeration due to a reaction between the coupling agents may cause a problem.
  • An amount of the silane coupling agent used preferably ranges from 4 to 18 wt. parts, and more preferably, ranges from 4 to 12 wt. parts to 100 wt. parts of thermosetting epoxy resin.
  • the fluorine surfactant among the components of the resin mixture plays a role of reducing surface tension thus to improve coating properties, and may include any one used in the related art, preferably, fluoroaliphatic polymeric ester. Particular examples may include FC4430 manufactured by 3M Co., 4300 manufactured by Novec Co., Capstone manufactured by DuPont Co., or the like. Further, an amount of the fluorine surfactant used herein may range from 0.5 to 5 wt. parts to 100 wt. parts of the thermosetting resin. If the fluorine surfactant is used in an amount of less than 0.5 wt. part to 100 wt. parts of the thermosetting resin, the used amount is too small to provide excellent coating properties.
  • the used amount of the fluorine surfactant exceeds 5 wt. parts to 100 wt. parts of the thermosetting resin, adhesiveness to the graphite layer 104 may be reduced.
  • the used amount of the fluorine surfactant ranges from 0.5 to 3 wt. parts to 100 wt. parts of the thermosetting resin.
  • the soft magnetic powder among the components of the resin mixture may include at least one or two or more selected from an Fe-Si-Al alloy, Fe-Si-Cr alloy, Fe-Si-B alloy, highflux, permalloy alloy, Ni-Zn ferrite, Mn-Zn ferrite, and preferably, at least one or two or more selected from the Fe-Si-Al alloy, Fe-Si-Cr alloy and Fe-Si-B alloy.
  • the soft magnetic powder may be used in an amount of 700 to 1,500 wt. parts to 100 wt. parts of the thermosetting epoxy resin. If the soft magnetic powder is included in an amount of less than 700 wt. parts to 100 wt.
  • the soft magnetic powder is used in an amount of exceeding 1,500 wt. parts to 100 wt. parts of the thermosetting epoxy resin, mechanical properties such as flexibility may be deteriorated although electromagnetic wave shielding effect is excellent.
  • the used amount of the soft magnetic powder preferably ranges from 850 to 1,350 wt. parts, and more preferably, ranges from 900 to 1,300 wt. parts to 100 wt. parts of the thermosetting epoxy resin.
  • the soft magnetic powder used herein may have an average diameter of 20 ⁇ m to 100 ⁇ m. If the average diameter of the soft magnetic powder is less than 20 ⁇ m, electromagnetic wave shielding or absorption performance may be deteriorated. If the average diameter of the soft magnetic powder exceeds 100 ⁇ m, coating properties may be reduced.
  • soft magnetic powders having an average diameter of 30 ⁇ m to 70 ⁇ m are preferably used.
  • the hardener among the components of the resin mixture may include at least one selected from an amine type hardener, anhydride type hardener and phenol type hardener, and preferably, at least one or more selected from the amine type hardener and anhydride type hardener.
  • a particular example of the hardener may be 4,4'-diaminodiphenylsulfone.
  • an amount of the hardener used herein may range from 2 to 30 wt. parts to 100 wt. parts of the thermosetting epoxy resin. If the hardener is used in an amount of less than 2 wt. parts to 100 wt. parts of the thermosetting epoxy resin, a hardening time may be excessively increased to reduce workability.
  • an amount of an adhesive component filled in the through holes 104a of the graphite layer 104 during the hot-pressing process may be decreased to cause a problem of reducing adhesiveness to the graphite layer 104.
  • the used amount of the hardener preferably ranges from 3 to 20 wt. parts, and more preferably, ranges from 4 to 15 wt. parts to 100 wt. parts of the thermosetting epoxy resin.
  • the moisture-proof agent among the components of the resin mixture is used for controlling a water content in the electromagnetic wave shielding layer 102 and a viscosity of the adhesive component, and may include, for example, at least one selected from aluminum sulfate, latex, silicon emulsion, poly(organosiloxane), hydrophobic polymer emulsion and silicon moisture-proof agent, or in combination of two or more thereof. Further, an amount of the moisture-proof agent may range from 1 to 25 wt. parts to 100 wt. parts of the thermosetting resin. If the used amount of the moisture-proof agent is less than 1 wt. part to 100 wt. parts of the thermosetting resin, the amount is too small to provide effects obtained by introducing the moisture-proof agent.
  • the moisture-proof agent is used in an amount of exceeding 25 wt. parts to 100 wt. parts of the thermosetting resin, there is a difficulty in controlling a proper water content of the electromagnetic wave shielding layer 102 due to excessive use thereof.
  • the used amount of the moisture-proof agent ranges from 5 to 20 wt. parts to 100 wt. parts of the thermosetting resin.
  • the resin mixture may be prepared by introducing a mixture of the above-described thermosetting epoxy resin, rubber binder, silane coupling agent, fluorine surfactant, soft magnetic powders, hardener and moisture-proof agent into an organic solvent, thereby adjusting a viscosity and solid content of a composition for forming an electromagnetic wave shielding layer 102.
  • the organic solvent may include at least one selected from methylethylketone, toluene, tetrahydrofuran (THF) and cyclohexanone.
  • the resin mixture may adjust the viscosity in a range of 800 to 1,200 cps (25°C) and the solid content in a range of 40 to 60 percent by weight ('wt.%'), and preferably, the viscosity in a range of 950 to 1,200 cps (25°C) and the solid content in a range of 48 to 56 wt.%.
  • the coated layer After applying (or coating) the resin mixture having the above-described constitutional compositions and a compositional ratio to the graphite layer 104, the coated layer may be subjected to drying to semi-harden the same, thereby forming an electromagnetic wave shielding layer 102 on the graphite layer 104.
  • the electromagnetic wave shielding layer 102 may have a mean thickness of 30 ⁇ m to 300 ⁇ m in the complex sheet for wireless charging 100.
  • the reason is that: if the mean thickness of the electromagnetic wave shielding layer 102 is less than 30 ⁇ m, electromagnetic wave shielding effects may be insignificant; and if the mean thickness of the electromagnetic wave shielding layer 102 exceeds 300 ⁇ m, the prepared layer is very unfavorable in an aspect of a decrease in thickness and has an economic disadvantage.
  • the mean thickness of the electromagnetic wave shielding layer 102 preferably ranges from 30 ⁇ m to 200 ⁇ m, and more preferably, ranges from 35 ⁇ m to 100 ⁇ m.
  • the graphite layer 104 may be combined with the electromagnetic wave shielding layer 102 at a bottom of the electromagnetic wave shielding layer 102.
  • the graphite layer 104 may be adhered to the electromagnetic wave shielding layer 102 by an adhesive component included in the electromagnetic wave shielding layer 102. That is, the graphite layer 104 may be adhered to the electromagnetic wave shielding layer 102 by the adhesive component derived from the electromagnetic wave shielding layer 102 without any alternative adhesive layer.
  • an entire thickness of the complex sheet for wireless charging 100 may be reduced to become a thin film sheet.
  • thermal conductivity from the electromagnetic wave shielding layer 102 to the graphite layer 104 may be improved.
  • the graphite layer 104 may play a role of discharging a heat generated from the coil 50.
  • the graphite layer 104 may be formed in a sheet or film shape.
  • the graphite layer 104 may have a plurality of through holes 104a formed therein.
  • the through hole 104a may be formed by perforating from one surface of the graphite layer 104 (that is, a surface facing the electromagnetic wave shielding layer 102) to the other surface of the graphite layer 104.
  • the inside of the through hole 104a may fill with the adhesive component 120 derived from the electromagnetic wave shielding layer 102.
  • Adhesion may be performed at an interface between the electromagnetic wave shielding layer 102 and the graphite layer 104 by the adhesive component contained in the electromagnetic wave shielding layer 102, and the adhesive component derived from the electromagnetic wave shielding layer 102 is filled in the through holes 104a to increase adhesiveness between the electromagnetic wave shielding layer 102 and the graphite layer 104.
  • the graphite layer 104 is formed in a plate-shaped structure, hence causing peel-off in a direction perpendicular to a thickness direction of the graphite layer 104 (that is, a direction parallel to the surface of the graphite layer 104) within the graphite layer 104, when a physical impact occurs (for example, when stripping a protective film or the like). Accordingly, forming the through holes 104a in the thickness direction of the graphite layer 104 (that is, a direction perpendicular to the surface of the graphite layer 104) may prevent the peel-off of the graphite layer 104 from further proceeding, thereby increasing the peel-off strength of the graphite layer 104.
  • the through hole 104a in the graphite layer 104 may improve a horizontal thermal conductivity.
  • the through hole 104a may be prepared to have a degree of transformation satisfying Equation 1 below, so as to achieve excellent horizontal thermal conductivity and high peel-off strength.
  • the degree of transformation may be represented by (internal area of corresponding through hole shape/circumferential length of corresponding through hole shape) 1/2 .
  • Equation 1 if the degree of transformation is less than 0.500, overall heat diffusion of the graphite layer 104 may be improved. However, the peel-off strength of each through hole 104a, and the peel-off strength between the electromagnetic wave shielding layer 102 and the graphite layer 104 may be decreased. On the other hand, if the degree of transformation exceeds 1,300, there may be a problem of increasing a vertical thermal conductivity although the peel-off strengths described above are improved.
  • a cross-sectional shape of the through hole 104a may include different cross-sectional shapes satisfying the above degree of transformation, as illustrated in FIG. 2. As shown in FIG. 2A, the cross-section of the through hole 104a may be formed in a circular shape.
  • a mean diameter of the through hole may range from 0.5 mm to 8mm. If the mean diameter of the through hole 104a is less than 0.5 mm, there may be a problem of deteriorating durability to thermal impact due to an increase in the number of through holes 104a provided in the graphite layer 104, and a reduction in a filling rate of the adhesive component filled in the through holes 104a.
  • the mean diameter of the through holes 104a preferably ranges from 0.5 to 5 mm, and more preferably, from 1 to 4 mm.
  • the cross-section of the through hole 104a may be formed in a circular shape.
  • a diameter ratio of an inscribed circle to a circumscribed circle of an oval shape may range from 1: 2 to 10.
  • a distance between the through holes 104a may defer to a size of the through hole 104, however, since the through holes are formed with a separation distance of, for example, 4 mm to 16 mm in a major axis direction of the graphite layer 104 (a transversal direction in FIG. 2) and 6 mm to 18 mm in a minor axis direction of the graphite layer 104 (a longitudinal direction in FIG. 2) based on a central part of each through hole 104, it is possible to secure a desired horizontal thermal conductivity of the graphite layer 104 and desired adhesiveness between the electromagnetic wave shielding layer 102 and the graphite layer 104, while preventing delamination between the graphite layers 104.
  • a distance between the through holes 104a may be a separation distance ranging from 6 mm to 14 mm in the major axis direction and ranging from 8 to 14 mm in the minor axis direction, respectively.
  • the cross-sectional shape of the through hole 104a may be at least one selected from circle, oval, + shape, x shape, ⁇ shape, L shape, I shape and linear shape, and such through holes 104a having various cross-sectional shapes may be formed in the graphite layer 104.
  • the through hole 104a may be formed to have such a cross-sectional shape that two through holes having a linear cross-section are perpendicularly crossed (for example, + shape or x shape).
  • the through hole 104a may be formed to have such a cross-sectional shape that a through hole having a linear cross-section is perpendicularly extending from one surface or an end of another through hole having a linear cross-section (for example, ⁇ shape or L shape).
  • an entire area of the through holes 104a may be set to have 2% to 30% of an entire area of upper or lower surface of the graphite layer 104. If the area of the through hole 104a is less than 2%, a peel-off strength between the electromagnetic wave shielding layer 102 and the graphite layer 104 may be reduced. If the area of the through hole 104a exceeds 30%, there are problems of increasing a vertical thermal conductivity while deteriorating heat diffusion performance although the above peel-off strength is excellent.
  • the entire area of the through holes 104a preferably ranges from 3.5 to 15%, and more preferably, from 3.5 to 10% to an entire area of the upper or lower surface of the graphite layer 104.
  • a graphite sheet (or film) forming the graphite layer 104 may include any typical graphite sheet used in the related art.
  • a graphite sheet including at least one selected from pyrolytic graphite and graphitized polyimide may be used.
  • the pyrolytic graphite refers to high purity graphite having high thermal conductivity and electric conductivity, is used at a high temperature, prepared by a vapor immersion method and may have a greatly developed microfine structure.
  • the graphitized polyimide may be prepared by following graphitization processes.
  • an advance preparation step of the graphitization may include laminating polyimide on a natural graphite sheet, then introducing the laminate into a calcination furnace.
  • polyimide may have a film form, this step may be conducted to prevent fusion between the films.
  • a first step of the graphitization may include a carbonization of polyimide at a temperature of 600 to 1,800°C for 2 to 7 hours. According to such carbonization as described above, nitrogen and hydrogen or other components in the polyimide as well as carbon may be removed.
  • heat treatment may be performed thereon at a temperature of 2,000°C to 3,200°C.
  • carbon atoms may be aligned in different forms. More particularly, pores may be present between carbon stacks in the polyimide after the first step. By passing these stacks through a mill roll at a temperature of 2,000 to 3,200°C, such pores may be eliminated while increasing a density of the stacks, thereby preparing graphitized polyimide having maximum heat radiation performance.
  • the electromagnetic wave shielding layer 102 and the graphite layer 104 are combined by the adhesive component derived from the electromagnetic wave shielding layer 102. Therefore, a thickness of the complex sheet for wireless charging 100 may be decreased thus to produce a thin film type complex sheet for wireless charging 100.
  • the electromagnetic wave shielding layer 102 and the graphite layer 104 are directly adhered to each other, heat transfer performance from the electromagnetic wave shielding layer 102 to the graphite layer 104 may be improved.
  • forming a plurality of through holes 104a in a thickness direction of the graphite layer 104 may minimize a vertical thermal conductivity of the graphite layer 104 while maximizing a horizontal thermal conductivity thereof, so as to improve heat radiation performance of the graphite layer 104.
  • the peel-off strength between the electromagnetic wave shielding layer 102 and the graphite layer 104 and the interlayer peel-off strength in the graphite layer 104 may be increased thus to improve impact resistance and durability of the complex sheet for wireless charging 100.
  • FIG. 3 is a flow chart illustrating a method for preparing the complex sheet for wireless charging according to the exemplary embodiment.
  • the electromagnetic wave shielding layer 102 is laminated on the graphite layer 104 (S101). That is, the electromagnetic wave shielding layer 102 may be formed and laminated on the graphite layer 104 having a plurality of through holes 104a formed therein.
  • a laminate in which the electromagnetic wave shielding layer 102 is laminated on the graphite layer 104 is introduced into a hot press machine, followed by conducting a hot-pressing process (S103) by heating and pressing the same at 145°C to 160°C under a pressure of 45 to 60 kgf/cm 2 .
  • the adhesive component in the electromagnetic wave shielding layer 102 is not sufficiently molten and may reduce the filling rate of the graphite layer 104 in the through holes 104. If the hot-pressing process temperature exceeds 160°C, the adhesive component in the electromagnetic wave shielding layer 102 is molten too much and may cause a deterioration in mechanical properties while having a difficulty in maintaining a shape of the electromagnetic wave shielding layer 102.
  • a pressure during hot pressing is less than 45 kgf/cm 2 , an amount of the adhesive component in the electromagnetic wave shielding layer 102 flowing into the through holes 104a may become small. Further, the pressure exceeding 60 kgf/cm 2 is economically disadvantageous.
  • the hot-pressing process may be executed by heating and pressing the laminate under the above pressure and temperature for 40 minutes to 80 minutes, and preferably, 50 minutes to 70 minutes. If the hot-pressing process is conducted for less than 50 minutes, the adhesive component is not sufficiently outflowed from the electromagnetic wave shielding layer 102 and an amount filled in the through holes 104a is small, hence causing a problem of reducing the peel-off strength. Further, a time for the hot-pressing process exceeding 70 minutes is economically disadvantageous.
  • heating during the hot-pressing process may be executed by heating a hot press from 10°C-35°C to 145°C-160°C at a heating rate of 3°C/min to 5°C/min.
  • the cooling of the hot press may be executed by cooling the hot press from 145°C-160°C to 10°C-35°C at a cooling rate of 3°C/min to 5°C/min.
  • the complex sheet for wireless charging 100 may have a horizontal thermal conductivity ranging from 100 to 1,000 W/m ⁇ k, and a vertical thermal conductivity of 1 to 15 W/m ⁇ k or less.
  • the horizontal thermal conductivity ranges from 200 to 1,000 W/m ⁇ k and the vertical thermal conductivity ranges from 1 to 10 W/m ⁇ k or less.
  • the complex sheet for wireless charging 100 may have a peel-off strength of the graphite layer 104 in a range of 390 gf/cm 2 to 770 gf/cm 2 , preferably, 450 gf/cm 2 to 750 gf/cm 2 , and more preferably, 500 gf/cm 2 to 740 gf/cm 2 , when the above peel-off strength is measured by 90° Peel Test according to JIS C 6741 standard.
  • the complex sheet for wireless charging 100 may have a peel-off strength of each through hole 104a in a range of 50 to 1,500 gf/hole, preferably, 250 to 1,000 gf/hole, and more preferably, 350 to 950 gf/hole.
  • FIG. 4 is a cross-sectional view illustrating a configuration of a complex sheet for wireless charging according to another exemplary embodiment.
  • a complex sheet for wireless charging 200 may include an electromagnetic wave shielding layer 202, a graphite layer 204 and an adhesive layer 206.
  • the graphite layer 204 is substantially the same as the graphite layer 104 illustrated in FIG. 1, and therefore will not be described in detail.
  • the electromagnetic wave shielding layer 202 is made of a material having heat radiation and electromagnetic wave shielding functions, which may be any typical metal foil used in the related art. Preferable examples thereof may include copper foil or aluminum foil. Further, the electromagnetic wave shielding layer 202 may have a mean thickness of 5 ⁇ m to 70 ⁇ m. The reason is that: if the mean thickness of the electromagnetic wave shielding layer 202 is less than 5 ⁇ m, there may be problems of poor appearance and an occurrence of tearing.; and if the mean thickness of the electromagnetic wave shielding layer 202 exceeds 70 ⁇ m, there are a difficulty in forming a thin film and a problem of reducing product flexibility. The mean thickness of the electromagnetic wave shielding layer 202 preferably ranges from 8 to 40 ⁇ m, and more preferably, from 8 to 35 ⁇ m.
  • the adhesive layer 206 may be formed between the electromagnetic wave shielding layer 202 and the graphite layer 204.
  • the adhesive layer 206 may adhere the electromagnetic wave shielding layer 202 and the graphite layer 204 to each other.
  • the adhesive layer 206 may include a high heat-resistant and heat radiation adhesive in order to effectively transfer heat from the electromagnetic wave shielding layer 202 to the graphite layer 204.
  • the adhesive layer 206 may contain a thermosetting resin, a rubber binder, a silane coupling agent, a fluorine surfactant, a hardener, a curing enhancer, a flame retardant and a moisture-proof agent.
  • the thermosetting resin may include at least one selected from a thermosetting epoxy resin, thermosetting phenoxy resin, thermosetting amino resin, thermosetting polyester resin and thermosetting polyurethane resin.
  • the thermosetting epoxy resin is used. More preferably, at least one or two or more selected from a bisphenol A epoxy resin, bisphenol F epoxy resin, novolac epoxy resin, halogen-containing epoxy resin may be included.
  • the bisphenol A epoxy resin and novolac epoxy resin is mixed in a weight ratio of 1 : 0.15-0.4, and preferably, 1 : 0.18-0.35, in terms of improving a melting point of the heat radiation adhesive and enhancing adhesiveness thereof.
  • the rubber binder may play a role of endowing bending resistance, and may include at least one selected from acryl rubber, silicone rubber, carboxylated nitrile elastomer and phenoxy, and preferably, one or two or more among the acryl rubber and silicon rubber may be included.
  • the above rubber binder used herein may be carboxyl elastomer, and preferably, carboxyl nitrile elastomer.
  • the carboxyl elastomer has weight average molecular weight of 180,000 to 350,000, preferably, 210,000 to 280,000, and more preferably, 215,000 to 255,000, in terms of securing desired bending-resistance of the complex sheet and desired heat-resistance of the heat radiation adhesive layer.
  • a used amount of the rubber binder may range from 25 to 100 wt. parts to 100 wt. parts of the thermosetting resin. The reason is that: if the rubber binder is used in an amount of less than 25 wt. parts to 100 wt.
  • the hardened adhesive layer has deteriorated flexibility to cause a problem of partially stripping the bonded portion between the electromagnetic wave shielding layer 202 and the graphite layer 204 when the complex sheet is bent; and if the rubber binder is used in an amount of exceeding 100 wt. parts to 100 wt. parts of the thermosetting resin, an amount of other components in the adhesive layer 206 is relatively decreased to hence reduce adhesiveness of the adhesive layer 206.
  • the used amount of the rubber binder ranges from 35 to 80 wt. parts to 100 wt. parts of the thermosetting resin.
  • the silane coupling agent may play a role of dispersing particles, which may include any typical silane coupling agent used in the related art.
  • at least one selected from glycidoxy(C2-C5 alkyl) trialkoxysilane, vinyl tri(C2-C5 alkoxy)silane and aminoethyl aminopropylsilane triol is used.
  • a used amount of the silane coupling agent may range from 1 to 10 wt. parts to 100 wt. parts of the thermosetting resin. The reason is that: if the silane coupling agent is used in an amount of less than 1 wt. part to 100 wt.
  • the used amount is too small to achieve particle dispersion effects; and if the silane coupling agent is used in an amount of exceeding 10 wt. parts to 100 wt. parts of the thermosetting resin, particle agglomeration may occur due to a reaction between the coupling agents.
  • the used amount of the silane coupling agent preferably ranges from 1 to 5 wt. parts to 100 wt. parts of the thermosetting resin.
  • the fluorine surfactant plays a role of reducing surface tension to improve coating properties, and may include any one typically used in the related art.
  • fluoroaliphatic polymeric ester is used. Particular examples thereof may include FC4430 manufactured by 3M Co., 4300 manufactured by Novec Co., Capstone manufactured by DuPont Co., or the like.
  • an amount of the fluorine surfactant used herein may range from 0.01 to 2 wt. parts to 100 wt. parts of the thermosetting resin. The reason is that: if the fluorine surfactant is used in an amount of less than 0.01 wt. part to 100 wt.
  • thermosetting resin this amount is too small to improve coating properties; and if the fluorine surfactant is used in an amount of exceeding 2 wt. parts to 100 wt. parts of the thermosetting resin, adhesiveness may be reduced.
  • the used amount of the fluorine surfactant preferably ranges from 0.02 to 1.2 wt. parts to 100 wt. parts of the thermosetting resin.
  • the hardener may include at least one selected from an amine type hardener, anhydride type hardener and phenol type hardener, and preferably, at least one or more selected from the amine type hardener and anhydride type hardener.
  • a particular example of the hardener may be 4,4'-diaminodiphenylsulfone.
  • an amount of the hardener used herein may range from 5 to 20 wt. parts to 100 wt. parts of the thermosetting resin. The reason is that: if the hardener is used in an amount of less than 5 wt. parts to 100 wt.
  • thermosetting resin durability may be deteriorated; and if the hardener is used in an amount of exceeding 20 wt. parts to 100 wt. parts of the thermosetting resin, adhesiveness may be reduced.
  • the used amount of the hardener preferably ranges from 8 to 17 wt. parts to 100 wt. parts of the thermosetting resin.
  • the curing enhancer may include at least one of aromatic amine, aliphatic amine and aromatic tertiary amine, and preferably, at least one selected from the aromatic amine and aromatic tertiary amine.
  • An amount of the curing agent used herein may range from 1 to 5 wt. parts to 100 wt. parts of the thermosetting resin. The reason is that: if the curing enhancer is used in an amount of less than 1 wt. part to 100 wt. parts of the thermosetting resin, a curing rate of a heat radiation adhesive is too low, hence deteriorating workability; and if the curing enhancer is used in an amount of exceeding 5 wt. parts to 100 wt.
  • the used amount of the curing enhancer preferably ranges from 1.5 to 4.5 wt. parts to 100 wt. parts of the thermosetting resin.
  • the flame retardant is used for providing flame retardant effect to a product, and may include any one typically used in the related art, and preferably, one selected from phosphorous flame retardant, inorganic flame retardant and chloride flame retardant, or a combination of two or more thereof. Particular examples thereof may include Clariant EXOLIT OP 935, H42M and/or H43M manufactured by Showa Denko Co. Further, an amount of the flame retardant used herein may range from 30 to 60 wt. parts to 100 wt. parts of the thermosetting resin. The reason is that: if the flame retardant is used in an amount of less than 30 wt. parts to 100 wt.
  • thermosetting resin it is difficult to achieve perfect flame-retardant effect; and if the flame retardant is used in an amount of exceeding 60 wt. parts to 100 wt. parts of the thermosetting resin, there may be a problem of reducing adhesiveness to the product by excessively using a flame retardant component.
  • the used amount of the flame retardant preferably ranges from 35 to 55 wt. parts to 100 wt. parts of the thermosetting resin.
  • the moisture-proof agent is used for adjusting a water content of the heat radiation adhesive layer and a viscosity of the heat radiation adhesive, and may include any one typically used in the related art. Particular examples thereof may include one selected from aluminum sulfate, latex, silicon emulsion, poly(organosiloxane), hydrophobic polymer emulsion, silicon moisture-proof agent, or the like, or a combination of two or more thereof.
  • An amount of the moisture-proof agent used herein may range from 0.5 to 10 wt. parts to 100 wt. parts of the thermosetting resin. The reason is that: if the moisture-proof agent is used in an amount of less than 0.5 wt. part to 100 wt.
  • the used amount of the moisture-proof agent preferably ranges from 1.5 to 8 wt. parts to 100 wt. parts of the thermosetting resin.
  • the adhesive layer 206 of the present invention may further include a thermoconductive filler and/or dispersant.
  • the thermoconductive filler may include one of graphite powder, carbon fiber tube (CNT), carbon black, carbon fiber, ceramic and metal powder, or a combination of two or more thereof, and preferably, one of graphite powders, ceramics and metal powders or a combination of two or more thereof.
  • this filler may be used in an amount of 45 to 1,100 wt. parts to 100 wt. parts of the thermosetting resin. The reason is that: if the thermoconductive filler is used in an amount of less than 45 wt. parts to 100 wt.
  • thermosetting resin heat transfer performance from the electromagnetic wave shielding layer 202 to the graphite layer 204 may be reduced; and if the thermoconductive filler is used in an amount of exceeding 1,100 wt. parts to 100 wt. parts of the thermosetting resin, adhesiveness to the graphite layer 204 may be deteriorated while greatly increasing a vertical thermal conductivity of the complex sheet.
  • the used amount of the thermoconductive filler preferably ranges from 75 to 800 wt. parts to 100 wt. parts of the thermosetting resin.
  • the thermoconductive filler used herein may have a mean particle diameter of 3 ⁇ m to 25 ⁇ m.
  • thermoconductive filler if the mean particle diameter of the thermoconductive filler is less than 3 ⁇ m, there may be a difficulty in dispersing particles; and if the mean particle diameter of the thermoconductive filler exceeds 25 ⁇ m, problems of reducing thin film coating properties and adhesiveness may be caused.
  • dispersant used herein may include any one typically used in the related art, and preferably, an acryl block amine-based dispersant.
  • a mixture of the curable resin, rubber binder, silane coupling agent, fluorine surfactant, hardener, curing enhancer, flame retardant and moisture-proof agent may be introduced into an organic solvent to adjust a viscosity of the moisture-proof agent and a solid content, a surface condition of the composition for forming a heat radiation adhesive layer may become favorable through the adjustment of viscosity and solid content, and adhesiveness to a material and particle orientation may be controlled.
  • the organic solvent used herein may include at least one selected from methylethylketone, toluene, tetrahydrofuran (THF) and cyclohexanone, or a combination of two or more thereof.
  • an applied amount of the heat radiation adhesive may be desirably defined so that a mean thickness of the heat radiation adhesive layer reaches a range of 2 ⁇ m to 25 ⁇ m based on the complex sheet after the hot-pressing process.
  • the mean thickness of the heat radiation adhesive layer in the complex sheet is less than 2 ⁇ m, adhesiveness (cohesion) between the electromagnetic wave shielding layer 202 and the graphite layer 204 may be deteriorated; and if the mean thickness of the heat radiation adhesive layer in the complex sheet exceeds 25 ⁇ m, it is economically disadvantageous and a thickness of the complex sheet is increased, hence being unfavorable. It is preferable to apply the heat radiation adhesive layer until the mean thickness reaches the range of 4 ⁇ m to 15 ⁇ m.
  • the adhesive layer 206 may be filled in the through holes 204a formed in the graphite layer 204 in the hot-pressing process of the complex sheet. More particularly, after introducing a laminate in which the electromagnetic wave shielding layer 202, adhesive layer 206 and graphite layer 204 are sequentially laminated into a hot press machine, the laminate may be subjected to a hot-pressing process by heating and pressing the same at 145°C to 160°C under a pressure of 45 to 60 kgf/cm 2 . In this regard, a part of the adhesive layer 206 may be filled in the through holes 204a.
  • the electromagnetic wave shielding layer 202 has been described as a metal foil, but it is not limited thereto. As illustrated and described in FIG. 1, this layer may also be made of a resin mixture including a thermosetting epoxy resin, rubber binder, silane coupling agent, fluorine surfactant, soft magnetic powder, hardener and curing enhancer.
  • Each of electromagnetic wave shielding sheets as the electromagnetic wave shielding layer 102 was prepared by the same procedures as described in Preparative Example 1-1 above, except that the electromagnetic wave shielding sheets had constitutional compositions listed in Table 1 below.
  • a plurality of through holes 104a were formed in a graphite sheet having a mean thickness of 17 ⁇ m (T Co., TGS15).
  • the punched through holes 104a were formed to have a mean particle diameter of 3 mm, an interval in the major axis direction of 10 mm and an interval in the minor axis distance of 12 mm between central parts of the through holes 104a, an entire area of the through holes 104a in a range of 3.9 to 4.1% to an entire area of upper surface of the graphite layer 104. Further, a degree of transformation of the through hole 104a was 0.866 according to Equation 1 below.
  • the graphite sheet in Preparative Example 2-1 was temporary bonded and laminated to the electromagnetic wave shielding sheet in Preparative Example 1-1.
  • the heat compressed sheet was taken out of the hot press, thereby providing an integrated complex sheet with electromagnetic wave shielding and heat radiation functions, wherein an adhesive component derived from the electromagnetic wave shielding layer 102 was filled in the through holes 104a of the graphite layer 104 having the shape as shown in FIG. 1.
  • the prepared integrated complex sheet 100 had an entire thickness of 67 ⁇ m, while the electromagnetic wave shielding layer 102 had a thickness of 50 ⁇ m and the graphite layer 104 had a thickness of 17 ⁇ m.
  • Integrated complex sheets having combinations listed in Table 3 below were prepared, respectively, by the same procedures as described in Example 1-1, and then, Examples 1-2 and 1-17 were executed, respectively.
  • the prepared integrated complex sheet 100 had an entire thickness of 67 ⁇ m, while the electromagnetic wave shielding layer 102 had a thickness of 50 ⁇ m and the graphite layer 104 had a thickness of 17 ⁇ m.
  • An integrated complex sheet was prepared by the same procedures as described in Example 1-1, except that heat compression was executed at 150°C and under a pressure of 50 kgf/cm 2 for 30 minutes.
  • An integrated complex sheet was prepared by the same procedures as described in Example 1-1, except that the graphite layer in Comparative Preparative Example 2-3 was temporary bonded and laminated to the electromagnetic wave shielding sheet in Preparative Example 1-1.
  • An integrated complex sheet was prepared by the same procedures as described in Example 1-1, except that heat compression was executed at 130°C under a pressure of 50 kgf/cm 2 for 60 minutes.
  • An integrated complex sheet was prepared by the same procedures as described in Example 1-1, except that heat compression was executed at 150°C under a pressure of 70 kgf/ cm 2 for 60 minutes.
  • the integrated complex sheets prepared in the respective examples and comparative examples were cut into a size of 100 mm x 10 mm (width and length).
  • the prepared sample was attached to a heating block and a temperature of the heating block was raised to 80°C (evaluation was conducted while raising the temperature to 80 °C which is in a temperature level of heat generated on AP chip in a smart phone).
  • a temperature of the heating block was measured using IR camera to determine a highest temperature (hot spot) and lowest temperature (cold spot) of the complex sheet. Then, heat diffusion performance of the complex sheet was determined by estimating a difference between the above temperatures.
  • ⁇ T difference in the above-two temperatures
  • Example 2-1 the integrated complex sheet prepared using the graphite sheet in Comparative Preparative Example 2-1, which was provided with the through holes having a degree of transformation of 1.5 and an entire area of through holes of 14.8%, it could be seen that the sheet had excellent peel-off strength compared to other examples.
  • this complex sheet showed a little higher hot spot temperature and somewhat deterioration in heat diffusion performance.
  • Example 2-2 prepared by introducing the graphite sheet having a degree of transformation of less than 0.500, which was prepared in Comparative Preparative Example 2-2, it could be seen that the sheet had excellent heat diffusion performance, however, showed a little decreased peel-off strength of each through hole.
  • Example 2-3 that included introducing a metal sheet (an electromagnetic wave shielding layer) prepared using the rubber binder in an amount of less than 160 wt. parts, it could be seen that the sheet had excellent peel-off strength and heat diffusion performance. However, when the composite was randomly bent, the bonded portion between the electromagnetic wave shielding layer and the graphite layer was partially peeled-off. The reason of this fact is considered that flexibility of the metal sheet itself was a little reduced.
  • Example 2-5 that was subjected to hot pressing for 30 minutes in the preparation of a complex sheet, it could be seen that the peel-off strength of each through hole was slightly decreased and heat diffusion performance was also slightly deteriorated.
  • the reason of this fact is considered that, since the adhesive component was not sufficiently derived from the electromagnetic wave shielding layer and a part of the through holes was not filled with the adhesive component, the peel-off strength was decreased and heat diffusion was inhibited due to a non-filled area.
  • Comparative Example 3 that included hot pressing at a temperature of less than 145°C, that is, at 130°C, since the adhesive component was not sufficiently derived from the electromagnetic wave shielding layer and a part of the through holes was not filled with the adhesive component, it resulted in that the peel-off strength and heat diffusion performance were considerably deteriorated.

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Abstract

L'invention concerne une feuille complexe pour charge sans fil et un procédé de préparation de celle-ci. La feuille complexe pour charge sans fil selon un mode de réalisation donné à titre d'exemple, comprend une couche de protection contre les ondes électromagnétiques conçue pour bloquer les ondes électromagnétiques générées dans une bobine de charge sans fil ; et une couche de graphite, qui est collée à la couche de protection contre les ondes électromagnétiques par la couche de protection contre les ondes électromagnétiques, et comprend une pluralité de trous traversants formés dans celle-ci, au moins une partie du trou traversant étant remplie d'un composant adhésif provenant de la couche de protection contre les ondes électromagnétiques.
PCT/KR2016/013187 2016-07-27 2016-11-16 Feuille complexe pour charge sans fil et procédé de fabrication de celle-ci WO2018021623A1 (fr)

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KR102280257B1 (ko) * 2019-10-29 2021-07-21 에스케이씨 주식회사 무선충전 패드, 무선충전 장치, 및 이를 포함하는 전기 자동차
KR102280259B1 (ko) * 2019-10-29 2021-07-21 에스케이씨 주식회사 무선충전 패드, 무선충전 장치, 및 이를 포함하는 전기 자동차
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KR20230155255A (ko) 2022-05-03 2023-11-10 주식회사 위츠 선택적으로 자성체가 밀봉된 무선 충전 모듈, 무선 충전 모듈에 포함된 자기장 차폐 시트 및 그 제조 방법

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