WO2021241567A1 - 電波吸収体 - Google Patents

電波吸収体 Download PDF

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Publication number
WO2021241567A1
WO2021241567A1 PCT/JP2021/019780 JP2021019780W WO2021241567A1 WO 2021241567 A1 WO2021241567 A1 WO 2021241567A1 JP 2021019780 W JP2021019780 W JP 2021019780W WO 2021241567 A1 WO2021241567 A1 WO 2021241567A1
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WO
WIPO (PCT)
Prior art keywords
radio wave
material layer
wave absorber
heat radiating
radiating material
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PCT/JP2021/019780
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English (en)
French (fr)
Japanese (ja)
Inventor
健史 小山
潤 田中
英人 西澤
Original Assignee
積水化学工業株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by 積水化学工業株式会社 filed Critical 積水化学工業株式会社
Priority to JP2021537833A priority Critical patent/JP7564106B2/ja
Priority to CN202180011793.5A priority patent/CN115066995A/zh
Publication of WO2021241567A1 publication Critical patent/WO2021241567A1/ja

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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
    • H05K7/00—Constructional details common to different types of electric apparatus
    • H05K7/20—Modifications to facilitate cooling, ventilating, or heating
    • 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

Definitions

  • the present invention relates to a radio wave absorber or the like.
  • radio wave absorber a material obtained by dispersing magnetic metal powder in various rubber or resin materials is used. Further, for example, a noise absorbing cloth in which a metal is adhered on the surface of the cloth has been reported (Patent Document 1).
  • Patent No. 5722608 Japanese Unexamined Patent Publication No. 2004-13464
  • the radio wave absorber may be installed near the IC chip in applications such as optical transceivers. In order to prevent a circuit short circuit, it is also required to have a certain level of insulation.
  • An object of the present invention is to provide a radio wave absorber having all of radio wave absorption, heat dissipation, and insulation.
  • the present inventor includes the heat radiating material layer 1, the conductive fiber sheet, and the heat radiating material layer 2, and the heat radiating material layer 1, the conductive fiber sheet, and the heat radiating material layer 2. They are stacked in order, (A) the resistance value by the non-contact resistance meter is 10 to 350 ⁇ / ⁇ , (B) the thermal conductivity in the stacking direction is 3 W / m ⁇ K or more, and (C) the stacking direction. It has been found that the above problem can be solved if the insulation breakdown voltage is 2.5 kV or more and the radio absorber is used. The present inventor has completed the present invention as a result of further research based on this finding. That is, the present invention includes the following aspects.
  • Item 1 The heat radiating material layer 1, the conductive fiber sheet, and the heat radiating material layer 2 are included. The heat radiating material layer 1, the conductive fiber sheet, and the heat radiating material layer 2 are laminated in this order.
  • the resistance value by the non-contact resistance tester is 10 to 350 ⁇ / ⁇ .
  • the thermal conductivity in the stacking direction is 3 W / m ⁇ K or more, and
  • the dielectric breakdown voltage in the stacking direction is 2.5 kV or more.
  • Radio wave absorber Item 2.
  • Item 2. The radio wave absorber according to Item 1 or 2, wherein the heat radiating material layer 1 has a thickness of 1200 ⁇ m or less.
  • Item 4. Item 2. The radio wave absorber according to any one of Items 1 to 3, wherein the heat radiating material layer 1 has a thickness of 300 ⁇ m or more.
  • Item 5. Item 2. The radio wave absorber according to any one of Items 1 to 4, wherein the heat radiating material layer 1 has a thickness of less than 300 ⁇ m.
  • Item 6. Item 2. The radio wave absorber according to any one of Items 1 to 5, wherein the conductive fiber sheet has a fiber base material containing a resin having a melting point of 250 ° C. or higher.
  • Item 7. Item 2.
  • Item 8. Item 2.
  • Item 9. Item 2.
  • Item 10. A housing having the radio wave absorber according to Items 1 to 9 on the inner surface of the housing.
  • Item 11 A housing having the radio wave absorber according to Items 1 to 9 in the opening of the housing.
  • Item 12. Item 10.
  • Item 14 An electronic device in which one surface of the radio wave absorber according to Items 1 to 9 is arranged so as to be in contact with a radio wave absorbing object.
  • Item 15 An electronic device in which one surface of the radio wave absorber according to Items 1 to 9 is arranged so as to be in contact with a heat radiating member.
  • radio wave absorber having all of radio wave absorption, heat dissipation, and insulation.
  • the heat radiating material layer 1, the conductive fiber sheet, and the heat radiating material layer 2 are included, and the heat radiating material layer 1, the conductive fiber sheet, and the heat radiating material layer 2 are laminated in this order (A). )
  • the resistance value by the non-contact resistance meter is 10 to 350 ⁇ / ⁇
  • (B) the thermal conductivity in the stacking direction is 3W / m ⁇ K or more
  • (C) the breakdown voltage in the stacking direction is 2.5kV.
  • the above is related to the radio wave absorber (in the present specification, it may be referred to as "the radio wave absorber of the present invention”). This will be described below.
  • the conductive fiber sheet is not particularly limited as long as it is a conductive fiber sheet.
  • the conductive fiber sheet preferably comprises a fiber substrate and a metal layer disposed on at least one surface of the fiber substrate.
  • the fiber base material is a base material containing a fiber or a fiber bundle as a material, and is not particularly limited as long as it is in the form of a sheet.
  • the fiber base material may contain components other than fibers and fiber bundles as long as the effects of the present invention are not significantly impaired.
  • the total amount of fibers and fiber bundles in the fiber substrate is, for example, 80% by mass or more, preferably 90% by mass or more, more preferably 95% by mass or more, still more preferably 99% by mass or more, and usually 100. Less than% by mass.
  • the material constituting the fiber is not particularly limited as long as it is a fibrous material or a material that can be formed into a fibrous form.
  • the fiber material include polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate, and modified polyester, polyethylene (PE) resin, polypropylene (PP) resin, polystyrene resin, and cyclic olefin resin.
  • Polyolefin resins such as resins, vinyl resins such as polyvinyl chloride and vinylidene chloride, polyvinyl acetal resins such as polyvinyl butyral (PVB), polyether ether ketone (PEEK) resins, polysulfone (PSF) resins, polyphenylene sulfide (PPS).
  • PVB polyvinyl butyral
  • PEEK polyether ether ketone
  • PSF polysulfone
  • PPS polyphenylene sulfide
  • the fiber may be composed of one kind of single fiber material, or may be a combination of two or more kinds of fiber materials.
  • the basis weight (basis weight) of the fiber base material is, for example, 1 to 500 g / m 2 , preferably 3 to 300 g / m 2 , and more preferably 5 to 150 g / m 2 .
  • the thickness of the fiber base material is, for example, 1 ⁇ m or more, preferably 5 ⁇ m or more, and more preferably 10 ⁇ m or more. Further, from the viewpoint of improving heat dissipation, the thickness of the fiber base material is, for example, 3000 ⁇ m or less, preferably 1500 ⁇ m or less, and more preferably 800 ⁇ m or less. The reason for this is not bound by a specific theory, but it is considered that by suppressing the thickness of the fiber base material, heat can be easily transferred between the heat radiating material layer 1 and the heat radiating material layer 2, and the heat radiating property is further improved. ..
  • the lower limit of the density of the fiber substrate is preferably 2.0 ⁇ 10 4 g / m 3 , more preferably 1.0 ⁇ 10 5 g / m 3 , and even more preferably 1.5 ⁇ 10 5 g. / M 3 .
  • the upper limit of the density of the fiber base material is preferably 8.0 ⁇ 10 5 g / m 3 , and more preferably 6.0 ⁇ 10 5 g / m 3 .
  • the reason for this is not bound by a specific theory, but by using a fiber base material with a specific range of density, the metal does not adhere only to the surface of the fiber base material, but penetrates into the inside of the fiber base material. It is considered that the absorption characteristics (particularly the absorbability) are improved. Further, it is considered that when the metal penetrates into the fiber base material, heat is easily transferred between the heat radiating material layer 1 and the heat radiating material layer 2 through the metal, and the heat radiating property is further improved.
  • the fiber base material examples include non-woven fabrics, meshes, woven fabrics, knitted fabrics and the like. Among these, a non-woven fabric is preferable from the viewpoint of flexibility, followability and the like.
  • the fiber base material preferably contains a resin having a melting point of 250 ° C. or higher.
  • the resin may be a material of a fiber constituting a fiber base material, or may be a component other than the fiber. Examples of such a resin include various LCP resins, PET resins, polyamide resins (nylon 66) and the like.
  • the layer structure of the fiber base material is not particularly limited.
  • the fiber base material may be composed of one type of fiber base material alone, or may be a combination (laminated) of two or more types of fiber base materials.
  • the melting point is the main absorption peak temperature measured and observed using a differential scanning calorimeter (DSC; for example, “TA3000” manufactured by METTLER CORPORATION) in accordance with JIS K7121. .. Specifically, when measuring with a DSC device, when 10 to 20 mg of a measurement sample is taken, sealed in an aluminum pan, nitrogen is flowed as a carrier gas at a flow rate of 100 mL / min, and the temperature is raised at 20 ° C./min. Measure the absorption peak of 1st run.
  • DSC differential scanning calorimeter
  • the temperature is raised to a temperature 50 ° C higher than the expected melting temperature at a heating rate of 50 ° C / min, and that temperature is used for 3 minutes or longer.
  • the mixture is cooled to 50 ° C. at a rate of 80 ° C./min, and then the endothermic peak of 2nd run is measured at a heating rate of 20 ° C./min.
  • Metal layer is placed directly on the fiber substrate or via another layer, in other words, on the surface of at least one of the two main surfaces of the fiber substrate.
  • the stacking relationship will be described with reference to FIG. 1, which is an example of the conductive fiber sheet.
  • the metal layer 1 is arranged on one surface of the main surface of the fiber base material 3.
  • the metal layer is not particularly limited as long as it is a layer containing metal as a material.
  • the metal layer may contain a component other than the metal as long as the effect of the present invention is not significantly impaired.
  • the amount of metal in the metal layer is, for example, 80% by mass or more, preferably 90% by mass or more, more preferably 95% by mass or more, still more preferably 99% by mass or more, and usually less than 100% by mass.
  • the metal constituting the metal layer is not particularly limited as long as it can exhibit radio wave absorption characteristics.
  • the metal include nickel, molybdenum, chromium, titanium, aluminum, gold, silver, copper, zinc, tin, platinum, iron, indium, alloys containing these metals, and alloys containing these metals or these metals. Metal compounds and the like.
  • the metal layer contains at least one metal element selected from the group consisting of nickel, molybdenum, chromium, titanium, and aluminum from the viewpoint of suppressing changes in the electromagnetic wave absorption characteristics of the conductive fiber sheet over time (durability). It is preferable to contain it.
  • the content thereof is, for example, 10% by mass or more, preferably 20% by mass or more, more preferably. It is 40% by mass or more, more preferably 60% by mass or more, and usually less than 100% by mass.
  • a metal layer containing molybdenum is preferably used from the viewpoint of durability and easy adjustment of sheet resistance.
  • the lower limit of the molybdenum content is not particularly limited, but from the viewpoint of further enhancing durability, 5% by weight is preferable, 7% by weight is more preferable, 9% by weight is further preferable, 11% by weight is further preferable, and 13% by weight is used. % Is particularly preferable, 15% by weight is very preferable, and 16% by weight is most preferable.
  • the upper limit of the molybdenum content is preferably 70% by weight, more preferably 30% by weight, still more preferably 25% by weight, still more preferably 20% by weight, from the viewpoint of facilitating the adjustment of the surface resistance value.
  • the metal layer contains molybdenum
  • nickel and chromium in addition to molybdenum in the metal layer, a more durable conductive fiber sheet can be obtained.
  • Alloys containing nickel, chromium and molybdenum include, for example, Hastelloy B-2, B-3, C-4, C-2000, C-22, C-276, G-30, N, W, X and the like. Various grades can be mentioned.
  • the metal layer contains molybdenum, nickel and chromium
  • the molybdenum content is 5% by weight or more
  • the nickel content is 40% by weight or more
  • the chromium content is 1% by weight or more.
  • the molybdenum, nickel and chromium contents are more preferably 7% by weight or more
  • the nickel content is 45% by weight or more
  • the chromium content is 3% by weight or more.
  • the molybdenum, nickel and chromium contents are more preferably 9% by weight or more, the nickel content is 47% by weight or more, and the chromium content is 5% by weight or more.
  • the molybdenum, nickel and chromium contents are more preferably 11% by weight or more, the nickel content is 50% by weight or more, and the chromium content is 10% by weight or more.
  • the contents of molybdenum, nickel and chromium it is particularly preferable that the molybdenum content is 13% by weight or more, the nickel content is 53% by weight or more, and the chromium content is 12% by weight or more.
  • the molybdenum content is 15% by weight or more, the nickel content is 55% by weight or more, and the chromium content is 15% by weight or more.
  • the molybdenum, nickel and chromium contents are most preferably 16% by weight or more, the nickel content is 57% by weight or more, and the chromium content is 16% by weight or more.
  • the nickel content is preferably 80% by weight or less, more preferably 70% by weight or less, and further preferably 65% by weight or less.
  • the upper limit of the chromium content is preferably 50% by weight or less, more preferably 40% by weight or less, and further preferably 35% by weight or less.
  • the metal layer may contain a metal other than the above molybdenum, nickel and chromium.
  • a metal include iron, cobalt, tungsten, manganese, titanium and the like.
  • the upper limit of the total content of the metals other than molybdenum, nickel and chromium is preferably 45% by weight, more preferably 40% by weight from the viewpoint of durability of the metal layer. %, More preferably 35% by weight, even more preferably 30% by weight, particularly preferably 25% by weight, and very preferably 23% by weight.
  • the lower limit of the total content of the metals other than molybdenum, nickel and chromium is, for example, 1% by weight or more.
  • the preferable upper limit of the content is 25% by weight, the more preferable upper limit is 20% by weight, the further preferable upper limit is 15% by weight, and the preferable lower limit is 1 from the viewpoint of the durability of the metal layer. It is% by weight.
  • the preferable upper limit of the content is 5% by weight, the more preferable upper limit is 4% by weight, and the further preferable upper limit is 3 independently from the viewpoint of the durability of the metal layer. It is% by weight, and the preferable lower limit is 0.1% by weight.
  • the preferable upper limit of the content is 8% by weight, the more preferable upper limit is 6% by weight, the further preferable upper limit is 4% by weight, and the preferable lower limit is 4% by weight from the viewpoint of the durability of the metal layer. 1% by weight.
  • the metal layer may contain silicon and / or carbon.
  • the content of the silicon and / or carbon is preferably 1% by weight or less, more preferably 0.5% by weight or less, respectively. ..
  • the content of the silicon and / or carbon is preferably 0.01% by weight or more.
  • the amount of metal element and / or metalloid element attached from the metal layer is not particularly limited as long as it can satisfy the sheet resistance described later.
  • the amount of the metal element and / or the metalloid element attached to the metal layer is, for example, 5 to 200 ⁇ g / cm2, preferably 10 to 100 ⁇ g / cm2, and more preferably 20 to 50 ⁇ g / cm2.
  • the amount of metal element and / or metalloid element attached from the metal layer can be determined by fluorescent X-ray analysis. Specifically, using a scanning fluorescent X-ray analyzer (for example, Rigaku's scanning fluorescent X-ray analyzer ZSX PrimusIII + or an equivalent product), the acceleration voltage is 50 kV, the acceleration current is 50 mA, and the integration time is 60 seconds. Analyze as. The X-ray intensity of the K ⁇ ray of the component to be measured is measured, and the intensity at the background position is also measured in addition to the peak position so that the net intensity can be calculated. From the calibration curve created in advance, the measured strength value can be converted into the adhesion amount. The same sample is analyzed 5 times, and the average value is taken as the average adhesion amount.
  • a scanning fluorescent X-ray analyzer for example, Rigaku's scanning fluorescent X-ray analyzer ZSX PrimusIII + or an equivalent product
  • the acceleration voltage is 50 kV
  • the acceleration current is 50 mA
  • the layer structure of the metal layer is not particularly limited.
  • the metal layer may be composed of a single metal layer of one type, or may be a combination of a plurality of metal layers of two or more types.
  • the conductive fiber sheet preferably has a barrier layer on at least one surface (preferably on both sides) of the metal layer.
  • the stacking relationship will be described with reference to FIG. 2, which is an example of the conductive fiber sheet.
  • the barrier layer 2 is arranged on one surface of the main surface of the fiber base material 3, and the barrier layer 2 is arranged.
  • the metal layer 1 is arranged on the surface of the barrier layer 2 (barrier layer 2a) opposite to the fiber base material 3 side, and the barrier layer is placed on the surface of the metal layer 1 opposite to the fiber base material 3 side.
  • a barrier layer 2 (barrier layer 2b) different from 2a is arranged.
  • the barrier layer is not particularly limited as long as it is a layer capable of protecting the metal layer and suppressing its deterioration, but it is preferably a composition different from that of the metal layer, and is a metal oxide constituting the metal layer. More preferably, they are different layers.
  • the material of the barrier layer include metals, metalloids, alloys, metal compounds, and metalloid compounds.
  • the barrier layer may contain components other than the above-mentioned materials as long as the effects of the present invention are not significantly impaired. In that case, the amount of the material in the barrier layer is, for example, 80% by mass or more, preferably 90% by mass or more, more preferably 95% by mass or more, still more preferably 99% by mass or more, and usually less than 100% by mass. ..
  • Examples of the metal preferably used for the barrier layer include nickel, titanium, aluminum, niobium, cobalt and the like.
  • Examples of the metalloid preferably used for the barrier layer include silicon, germanium, antimony, bismuth and the like.
  • the metal compound and the semi-metal compound used for the barrier layer are SiO2, SiOx (X represents an oxidation number, 0 ⁇ X ⁇ 2), Al2O3, MgAl2O4, CuO, CuN, TiO2, TiN, AZO (aluminum). Dope zinc oxide) and the like.
  • the barrier layer preferably contains at least one element selected from the group consisting of nickel, silicon, titanium, and aluminum. Among these, silicon is preferably mentioned.
  • the amount of metal element and / or metalloid element attached from the barrier layer is not particularly limited as long as it can satisfy the sheet resistance described later.
  • the amount of the metal element and / or the metalloid element attached to the barrier layer is, for example, 1 to 50 ⁇ g / cm 2 , preferably 2 to 20 ⁇ g / cm 2 , and more preferably 4 to 10 ⁇ g / cm 2 .
  • the layer structure of the barrier layer is not particularly limited.
  • the barrier layer may be composed of one type of barrier layer alone, or may be a combination of two or more types of barrier layers.
  • Heat dissipation material layer In the present specification, the heat radiating material layer 1 and the heat radiating material layer 2 may be collectively referred to as a "heat radiating material layer".
  • the radio wave absorber of the present invention is preferably used so that the heat radiating material layer 1 side is the radio wave incident surface.
  • the heat radiating material layer is a layer containing the heat radiating material, and is not particularly limited as long as it can satisfy the characteristics (A) to (C) of the present invention described later in the radio wave absorber of the present invention.
  • the heat radiating material layer preferably contains a binder resin and heat radiating particles.
  • the binder resin is not particularly limited as long as it can disperse heat-dissipating particles.
  • the binder resin include silicone resin, crosslinkable rubber, epoxy resin, polyimide resin, bismaleimide resin, benzocyclobutene resin, phenol resin, unsaturated polyester, diallyl phthalate resin, polyurethane, polyimide silicone, and thermosetting polyphenylene ether.
  • examples thereof include heat-curable modified polyphenylene ether and fluororubber.
  • the binder resin may be used alone or in combination of two or more.
  • a silicone resin can be preferably used from the viewpoint of easy processing, high heat resistance and high insulating properties.
  • the silicone resin is preferably a silicone resin composed of a main agent of a liquid silicone gel and a curing agent. Examples of such a silicone resin include an addition reaction type liquid silicone resin, a hot vulcanization type mirable type silicone resin using a peroxide for vulcanization, and the like.
  • the content of the binder resin is, for example, 1 to 70% by mass with respect to 100% by mass of the heat radiating material layer.
  • the content is preferably 5 to 50% by mass, more preferably 15 to 30% by mass, from the viewpoint of improving processability, thermal conductivity, and dispersibility of the heat radiating material particles.
  • the heat-dissipating particles are not particularly limited as long as they can satisfy the characteristics (A) to (C) of the present invention described later when the heat-dissipating material layer is formed together with the binder resin.
  • heat-dissipating particles examples include metal oxides (alumina, magnesium oxide, etc.), metal nitrides (aluminum nitride, boron nitride, silicon nitride, etc.), metal carbides (silicon carbide, etc.) and other ceramics, bariums, magnesiums, etc.
  • Metals such as calcium, gold, silver, copper, steel, titanium oxide, aluminum, tin, zinc, zirconium, duralumin, molybdenum, beryllium and their hydroxides, minerals such as talc, carbon materials (carbon nanotubes, carbon nano) Fiber, filler, graphene, graphite, diamond, etc.) and the like.
  • the shape of the heat-dissipating particles is not particularly limited, and examples thereof include fibrous, needle-like, scaly, spherical, and pellet-like.
  • heat-dissipating particles examples include ceramics such as alumina, and more preferably alumina and the like, from the viewpoint of having excellent insulating properties and being suitably used for the heat-dissipating material layer 1.
  • a carbon material more preferably a fibrous carbon material (carbon fiber) and the like can be mentioned.
  • the particle size (average of major axis and minor axis) of the heat-dissipating particles is not particularly limited, and is, for example, 0.1 to 50 ⁇ m, preferably 0.2 to 15 ⁇ m.
  • the particle size can be measured by a microscope, a scanning electron microscope (SEM), or the like, and can be a number average value of the particle sizes of a plurality of (for example, 50) samples arbitrarily selected.
  • the heat-dissipating particles may be one kind alone or a combination of two or more kinds.
  • the content of the heat-dissipating particles is, for example, 30 to 99% by mass with respect to 100% by mass of the heat-dissipating material layer.
  • the content is preferably 50 to 95% by mass, more preferably 70 to 85% by mass from the viewpoint of processability and thermal conductivity.
  • the thickness of the heat radiating material layer is not particularly limited.
  • the thickness of the heat radiating material layer 1 is preferable because the insulating property can be further improved by increasing the thickness of the heat radiating material layer on the incident surface side. Is 100 ⁇ m or more, more preferably 150 ⁇ m or more, and even more preferably 300 ⁇ m or more.
  • the thickness of the heat radiating material layer 1 is preferably 1500 ⁇ m or less, more preferably 1200 ⁇ m or less, from the viewpoint of improving radio wave absorption and heat dissipation.
  • the thickness of the heat radiating material layer 2 is not particularly limited. From the viewpoint of heat dissipation and handleability, the thickness of the heat dissipation material layer 2 is preferably 100 to 3000 ⁇ m, more preferably 200 to 2000 ⁇ m.
  • the thickness of the heat radiating material layer 1 is preferably less than 300 ⁇ m.
  • the heat radiating property can be further improved by reducing the thickness of the heat radiating material layer on the incident surface side, and the overall thickness can be suppressed. can.
  • the thermal conductivity of the heat radiating material layer is not particularly limited, but the thermal conductivity of the heat radiating material layer is, for example, 0.5 W / m ⁇ K or more, preferably 3 W / m ⁇ K or more.
  • the upper limit of the thermal conductivity of the heat radiating material layer is not particularly limited, but is, for example, 20 W / m ⁇ K and 10 W / m ⁇ K.
  • the thermal conductivity of the heat radiating material layer 1 is preferably 0.5 W / m ⁇ K or more, more preferably 1 W / m ⁇ K or more.
  • the upper limit of the thermal conductivity of the heat radiating material layer 1 is not particularly limited, but is preferably 4 W / m ⁇ K, more preferably 2 W / m ⁇ K from the viewpoint of achieving both insulation and heat dissipation.
  • the thermal conductivity of the heat radiating material layer 2 is preferably 6 W / m ⁇ K or more, more preferably 10 W / m ⁇ K or more.
  • the upper limit of the thermal conductivity of the heat radiating material layer 2 is not particularly limited, but is, for example, 50 W / m ⁇ K and 25 W / m ⁇ K.
  • the method for controlling the thermal conductivity of the heat radiating material layer is not particularly limited, and can be adjusted, for example, by the type, shape, content, thickness of the heat radiating material layer, and the like described above.
  • the above-mentioned "thermal conductivity of the heat radiating material layer" is preferably the thermal conductivity in the stacking direction of the radio wave absorber when used for the radio wave absorber.
  • the layer structure of the heat radiating material layer is not particularly limited.
  • the heat radiating material layer may be composed of one type of heat radiating material layer alone, or may be a combination of two or more types of heat radiating material layers.
  • the radio wave absorber of the present invention includes the heat radiating material layer 1, the conductive fiber sheet, and the heat radiating material layer 2, and is particularly limited as long as the heat radiating material layer 1, the conductive fiber sheet, and the heat radiating material layer 2 are laminated in this order. Not restricted. These three layers may be arranged adjacent to each other or may be arranged via another layer (for example, an adhesive layer), but preferably adjacent to each other (without interposing another layer). ) Have been placed. The stacking relationship will be described with reference to FIG. 3, which is an example of the radio wave absorber of the present invention.
  • the heat radiating material layer 110 is on one surface of the main surface of the conductive fiber sheet 9. Is arranged, and the heat radiating material layer 211 is arranged on the other surface of the main surface of the conductive fiber sheet 9.
  • a part of the material of the heat radiating material layer may permeate a part or all of the conductive fiber sheet.
  • the radio wave absorber of the present invention has (A) a resistance value of 10 to 350 ⁇ / ⁇ by a non-contact resistance tester, (B) a thermal conductivity of 3 W / m ⁇ K or more in the stacking direction, and (C). It has the characteristic that the dielectric breakdown voltage in the stacking direction is 2.5 kV or more. Combined with these characteristics and the above-mentioned layer structure, it is possible to have all of radio wave absorption, heat dissipation, and insulation.
  • the resistance value in the characteristic (A) is preferably 10 to 350 ⁇ / ⁇ , more preferably 20 to 250 ⁇ / ⁇ , and further preferably 40 to 150 ⁇ / ⁇ . When the resistance value is within the above range, the absorption performance of the radio wave absorber becomes excellent.
  • the resistance value can be measured as follows.
  • a non-contact resistance measuring instrument manufactured by Napson Corporation, EC-80P or an equivalent product thereof
  • EC-80P or an equivalent product thereof
  • the method of controlling the resistance value is not particularly limited.
  • Examples of the method for controlling the resistance value include a method for controlling the amount of metal element and / or metalloid element attached to the above-mentioned metal layer.
  • the thermal conductivity in the stacking direction in the characteristic (B) is preferably 3 W / m ⁇ K or more, more preferably 6 W / m ⁇ K or more, and further preferably 8 W / m ⁇ K or more.
  • the upper limit of the thermal conductivity in the stacking direction in the characteristic (B) is not particularly limited, but is, for example, 20 W / m ⁇ K. From the viewpoint of having sufficient insulating properties and excellent heat dissipation, it is preferably 15 W / m ⁇ K or less, more preferably 10 W / m ⁇ K or less.
  • the thermal conductivity can be measured by using a thermal conductivity measuring device (manufactured by Center Graphics, T3Star DynaTIM Tester, or an equivalent product thereof) in accordance with ASTM-D5470.
  • the method of controlling the thermal conductivity is not particularly limited.
  • Examples of the method for controlling the thermal conductivity include a method for adjusting the thermal conductivity of the heat radiating material layer, a method for adjusting the thickness of the fiber base material, a method for adjusting the density of the fiber base material, and the like.
  • the dielectric breakdown voltage in the characteristic (C) is preferably 2.5 kV or more, more preferably 3.0 kV or more, and further preferably 4.0 kV or more from the viewpoint of excellent insulation. Further, from the viewpoint of excellent heat dissipation, it is preferably 15 kV or less, more preferably 10 kV or less, and further preferably 8 kV or less. In one aspect of the present invention, it is preferable that the dielectric breakdown voltage in the stacking direction is 2.5 kV or more.
  • the dielectric breakdown voltage conforms to ASTM-D149, and a withstand voltage tester (7343 AC Withstand Voltage Tester manufactured by EXTECH Electricals, or an equivalent product thereof) is used, a sample is brought into contact with the electrodes, and 0.5 kV / sec is applied to both electrodes. An AC voltage is applied so that the voltage rises at a speed, and the voltage at the time of dielectric breakdown is measured.
  • a withstand voltage tester 7343 AC Withstand Voltage Tester manufactured by EXTECH Electricals, or an equivalent product thereof
  • the method of controlling the breakdown voltage is not particularly limited.
  • Examples of the method for controlling the dielectric breakdown voltage include a method of adjusting the thickness of the heat radiating material layer, a method of adjusting the type of heat radiating particles contained in the heat radiating material layer, a method of adjusting the type of binder contained in the heat radiating material layer, and the like. Can be mentioned.
  • the radio wave absorber of the present invention comprises a step of adhering a metal, a barrier layer component, etc. to the surface of the fiber base material to obtain a conductive fiber sheet, and a step of laminating each layer including the conductive fiber sheet and the heat radiating material layer. It can be obtained by the method including.
  • the adhesion can be performed by, for example, a sputtering method, a vacuum vapor deposition method, an ion plating method, a chemical vapor deposition method, a pulse laser deposition method, or the like.
  • the sputtering method is preferable from the viewpoint of film thickness controllability, radio wave absorption characteristics, and the like.
  • the sputtering method is not particularly limited, and examples thereof include DC magnetron sputtering, high frequency magnetron sputtering, and ion beam sputtering. Further, the sputtering apparatus may be a batch system or a roll-to-roll system.
  • the gradient of the amount of metal adhering between the surface and the inside thereof can be adjusted by the gas pressure at the time of sputtering.
  • the metal can be adhered to the inside of the fiber base material deeper and can be distributed with a gentle gradient. This further improves the radio wave absorption.
  • the method for molding the heat radiating material layer in the present invention is not particularly limited.
  • press molding, injection molding, extrusion molding, calender molding, roll molding, doctor blade molding, printing, coating and the like can be mentioned.
  • the method of laminating each layer including the conductive fiber sheet and the heat radiating material layer is not particularly limited.
  • a method of impregnating the conductive fiber sheet with the heat-dissipating material layer material before curing and then curing the heat-dissipating material layer material, a method of laminating via an adhesive layer, and the like can be mentioned.
  • the radio wave absorber of the present invention is preferably used so that the heat radiating material layer 1 side is the radio wave incident surface.
  • the radio wave absorber of the present invention has the ability to absorb unnecessary electromagnetic waves in one aspect thereof, it can be suitably used, for example, as an optical transceiver or a radio wave countermeasure member in a next-generation mobile communication system (5G). Also, for other purposes, it should be used for the purpose of suppressing radio wave interference and reducing noise in the millimeter-wave radar used in intelligent transportation systems (ITS) and automobile collision prevention systems that communicate information between automobiles, roads, and people. Can be done.
  • the frequency of the radio wave targeted by the radio wave absorber of the present invention is, for example, 1 GHz or more and 150 GHz or less, preferably 1.5 GHz or more and 85 GHz or less, and more preferably 40 GHz or less.
  • the radio wave absorber of the present invention it is preferable to arrange one surface of the radio wave absorber so as to be in contact with the radio wave absorbing object, and it is more preferable to arrange the other surface so as to be in contact with the heat radiating member. preferable.
  • the stacking relationship will be described with reference to FIG. 5, which is an example of the usage mode of the radio wave absorber of the present invention.
  • the inner wall of the IC chip 7 arranged on the inner wall of the metal housing 4 The heat dissipation material layer of the radio wave absorber 8 of the present invention is arranged so as to be in contact with the surface on the opposite side, and the heat spreader 12 is arranged on the surface of the other heat radiation material layer of the radio wave absorber of the present invention. Will be done.
  • An electronic device arranged so that one surface of the radio wave absorber is in contact with a radio wave absorbing object is also one of the present inventions.
  • An electronic device arranged so that one surface of the radio wave absorber is in contact with the heat radiating member is also one of the present inventions.
  • the object of radio wave absorption is not particularly limited.
  • radio wave absorbing objects include electronic parts such as LSI, circuit front surface or back surface such as glass epoxy board and FPC, connection cables and connectors between parts, housing for electronic parts / devices, and back of holder.
  • a table, a power line, a cable such as a transmission line, or the like can be mentioned.
  • the heat radiating member is not particularly limited as long as it conducts the generated heat and dissipates it to the outside. Examples of the heat radiating member include a radiator, a cooler, a heat sink, a heat spreader, a die pad, a printed circuit board, a cooling fan, a Pelche element, a heat pipe, a metal cover, a housing, and the like.
  • the radio wave absorption target is a noise source and often generates heat. Since the radio wave absorber of the present invention is excellent in radio wave absorption and heat dissipation, it can be suitably used as a heat transfer member.
  • the radio wave absorber of the present invention can be used in one embodiment by covering the periphery of the radio wave absorbing object. Therefore, it is appropriately molded according to the shape of the object.
  • the molded product is referred to as a "radio wave absorbing molded product" in the present specification.
  • a radio wave absorbing molded body in which a radio wave absorber is arranged around a radio wave absorbing object is also one of the present inventions. This case will be described with reference to FIG. 5, which is an example of the usage mode of the radio wave absorber of the present invention.
  • the present invention covers the entire IC chip 7 around the IC chip 7.
  • the radio wave absorber 8 of the above is arranged.
  • the radio wave absorber of the present invention is arranged at a position away from the source of radio wave noise and is used so as to cover the periphery of the radio wave absorbing object, thereby more effectively exhibiting the performance of absorbing unnecessary radio wave noise. can do.
  • FIG. 4 is an example of the usage mode of the radio wave absorber of the present invention.
  • the IC chip 7 is arranged on the inner wall of the metal housing 4, and the inner wall is described.
  • the radio wave absorber 5 of the present invention is arranged on the inner wall facing the above. Further, by arranging it at a position away from the source of radio wave noise, it becomes difficult to interfere with heat dissipation of heat generated from an LSI or the like.
  • the radio wave absorber of the present invention is preferably arranged at a position ⁇ / 2 ⁇ or more away from the source of radio wave noise.
  • ⁇ indicates the wavelength of the target radio wave.
  • the housing itself can become a radio wave noise source due to the cavity resonance phenomenon.
  • the housing containing an electronic device or the like when the housing containing an electronic device or the like has an opening, the housing having excellent radio absorption can be obtained by attaching the housing to the opening. can.
  • FIG. 4 is an example of the usage mode of the radio wave absorber of the present invention.
  • the IC chip 7 is arranged on the inner wall of the metal housing 4 having an opening.
  • the radio wave absorber 6 of the present invention is arranged in the opening.
  • the radio wave absorber of the present invention in the opening of the housing, the noise generated from the housing can be reduced.
  • a housing having the radio wave absorber of the present invention in the opening of the housing and an electronic device having the housing are also one of the present inventions.
  • the amount of element adhered to the conductive fiber sheet was determined by fluorescent X-ray analysis. Specifically, analysis was performed using a scanning fluorescent X-ray analyzer (scanning fluorescent X-ray analyzer ZSX PrimusIII + manufactured by Rigaku) with an acceleration voltage of 50 kV, an acceleration current of 50 mA, and an integration time of 60 seconds. The X-ray intensity of the K ⁇ ray of the component to be measured was measured, and the intensity at the background position was also measured in addition to the peak position so that the net intensity could be calculated. From the calibration curve prepared in advance, the measured strength value was converted into the adhesion amount. The same sample was analyzed 5 times, and the average value was taken as the average adhesion amount.
  • a scanning fluorescent X-ray analyzer scanning fluorescent X-ray analyzer ZSX PrimusIII + manufactured by Rigaku
  • the X-ray intensity of the K ⁇ ray of the component to be measured was measured, and the intensity at the background position was also measured in addition to the peak position so that the
  • Liquid additive reaction type silicone (Silmer G102, hereinafter Preparation Example 1) filled with 85% wt% of aluminum oxide (AS40 manufactured by Showa Denko KK) as a heat conductive filler is seated by doctor blade molding, and one side thereof.
  • the above-mentioned conductive fiber sheet was laminated and cured by heating, and the heat radiating material layer 1 and the conductive fiber sheet were laminated.
  • the heat-dissipating material layer 2 MANION-D3 manufactured by Sekisui Polymatec Co., Ltd. was used as a liquid silicone (Silmer G102) of 10 ⁇ m.
  • a radio wave absorber (radiating material layer 1 / conductive fiber sheet / heat radiating material layer 2) was obtained by adhesively laminating as a layer.
  • Examples 2 to 14 and Comparative Examples 1 to 5 Except for changing the type of fiber base material, the amount of element adhesion, the layer structure of the layer formed by spatter, the material of the heat dissipation material layer, the thickness of the heat dissipation material layer, the presence or absence of the heat dissipation material layer, etc., as described in the table below.
  • a radio wave absorber was obtained in the same manner as in Example 1.
  • the radio wave absorber that is, the laminated body composed of the conductive fiber sheet / the heat radiating material layer 2 was obtained without forming the heat radiating material layer 1.
  • Fiber base material 1 Melt blow non-woven fabric, material LCP (melting point 350 ° C), basis weight 6 g / m2, thickness 24 ⁇ m
  • Fiber base material 2 mesh, material PET (melting point 255 ° C.), basis weight 19 g / m2, thickness 100 ⁇ m.
  • the alloys used for the barrier layer are as follows. Monel (CuNi): Ni65%, Cu33%, Fe2%.
  • the types of the heat radiating material layer 2 are as follows. ⁇ Sekisui Polymatec Co., Ltd. MANION-D3 thickness 2000 ⁇ m thermal conductivity 19 W / m ⁇ K carbon fiber contained ⁇ Sekisui Polymatec Co., Ltd. PT-V thickness 2000 ⁇ m thermal conductivity 12 W / m ⁇ K carbon fiber contained ⁇ Sekisui Polymatec Co., Ltd. MANION-50 ⁇ Thickness 2000 ⁇ m Thermal conductivity 17W / m ⁇ K Carbon fiber containing ⁇ Sekisui Polymatec Co., Ltd.
  • thermo conductivity measuring device manufactured by Menteor Graphics, T3Star DynaTIM Tester was used to measure the thermal conductivity in the stacking direction of the radio wave absorber in accordance with ASTM-D5470.
  • the radio wave absorption was evaluated according to the following criteria based on the loss rate at each frequency.
  • ⁇ loss rate is 0.7 or more
  • ⁇ loss rate is 0.50 or more and less than 0.7.
  • X The loss rate is less than 0.5.
  • radio wave reflectivity The radio wave reflectivity was evaluated based on S11 at each frequency according to the following criteria. ⁇ : S11 is 0.10 or less. ⁇ : S11 is more than 0.10 and 0.20 or less. X: S11 exceeds 0.20.
  • Radio wave absorber of the present invention located on the inner wall of the metal housing
  • Radio wave absorber of the present invention located in the opening
  • IC chip Radio wave absorber of the present invention
  • Conductive fiber sheet 10 Heat dissipation material layer 1 11 Heat dissipation material layer 2 12 heat spreader

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
PCT/JP2021/019780 2020-05-26 2021-05-25 電波吸収体 WO2021241567A1 (ja)

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