WO2021060353A1 - ABSORBEUR D'ONDE λ/4 - Google Patents

ABSORBEUR D'ONDE λ/4 Download PDF

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Publication number
WO2021060353A1
WO2021060353A1 PCT/JP2020/035970 JP2020035970W WO2021060353A1 WO 2021060353 A1 WO2021060353 A1 WO 2021060353A1 JP 2020035970 W JP2020035970 W JP 2020035970W WO 2021060353 A1 WO2021060353 A1 WO 2021060353A1
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WIPO (PCT)
Prior art keywords
radio wave
thickness
layer
wave absorber
dielectric layer
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PCT/JP2020/035970
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English (en)
Japanese (ja)
Inventor
幸子 中尾
勝紀 武藤
哲郎 澤田石
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積水化学工業株式会社
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Priority to JP2020564511A priority Critical patent/JPWO2021060353A1/ja
Publication of WO2021060353A1 publication Critical patent/WO2021060353A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B32B7/025—Electric or magnetic properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
    • 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 ⁇ / 4 type radio wave absorber and the like.
  • Patent Document 1 discloses an electromagnetic wave absorber having a bandwidth of 2 GHz or more in a frequency band having an electromagnetic wave absorption amount of 20 dB or more in a frequency band of 60 to 90 GHz.
  • the radio wave absorption characteristics have been controlled by making the thickness of the dielectric layer as uniform as possible.
  • An object of the present invention is to provide a new technique for controlling radio wave absorption characteristics in a ⁇ / 4 type radio wave absorber.
  • the present inventor has found that even if a step is provided in the dielectric layer, good radio wave absorption characteristics can be exhibited in a target wavelength range.
  • the radio wave absorption peak position when the step is provided almost coincides with the radio wave absorption peak position calculated by regarding the area average thickness of the dielectric layer having the step as the thickness of the dielectric layer. That is, it was found that the radio wave absorption peak position when the step is provided can be controlled based on the respective thicknesses of the thick region and the thin region of the dielectric layer and their area ratios. In the past, it was required to make the thickness of the dielectric layer as uniform as possible, and this result was surprising. The present inventor has completed the present invention as a result of further research based on these findings.
  • the present invention includes the following aspects.
  • a ⁇ / 4 type radio wave absorber including a resistance film, a dielectric layer, and a reflective layer, wherein the dielectric layer has two or more regions having a thickness difference of 15 ⁇ m or more.
  • Item 2 The ⁇ / 4 type radio wave absorber according to Item 1, wherein the difference in thickness is 350 ⁇ m or less.
  • Item 3 The ⁇ / 4 type radio wave absorber according to Item 1 or 2, wherein the thickness of each of the two or more regions is 80 to 120% with respect to the area average thickness of the dielectric layer of 100%.
  • Item 4. The ⁇ / 4 type radio wave absorber according to any one of Items 1 to 3, wherein the area average thickness of the dielectric layer is 100 to 800 ⁇ m.
  • Item 5 The ⁇ / 4 type radio wave absorber according to any one of Items 1 to 4, wherein the radio wave absorption amount at 60 to 90 GHz is 15 dB or more.
  • a ⁇ / 4 type radio wave absorber containing a resistance film, a dielectric layer, and a reflection layer, and having an Rz of 7.5 ⁇ m or more on at least one of the resistance film layer side surface and the reflection layer side surface surface.
  • a ⁇ / 4 type radio wave absorber that includes a resistance film, a dielectric layer, and a reflective layer, and has a thickness difference of 15 ⁇ m or more on the outermost surface.
  • Item 7 A molded product with a radio wave absorber, comprising the molded product and the ⁇ / 4 type radio wave absorber according to any one of Items 1 to 5 attached to the molded product.
  • Item 8. A molded product with a radio wave absorber, which is a millimeter-wave radar.
  • a ⁇ / 4 type radio wave absorber member including a resistance film and a dielectric layer, wherein the dielectric layer has two or more regions having a thickness difference of 25 ⁇ m or more.
  • the radio wave absorption peak position when the dielectric layer is provided with a step has a step based on the knowledge that the radio wave absorption peak position can be controlled based on the respective thicknesses of the thick region and the thin region of the dielectric layer and their area ratios. It is possible to provide a ⁇ / 4 type radio wave absorber including a dielectric layer, and further, a ⁇ / 4 type radio wave absorber having a step formed following the step on the surface.
  • a schematic cross-sectional view of an example of the ⁇ / 4 type radio wave absorber of the present invention is shown.
  • a schematic cross-sectional view of an example of the ⁇ / 4 type radio wave absorber of the present invention is shown.
  • a top view (A) and a schematic cross-sectional view (B) of an example of the ⁇ / 4 type radio wave absorber of the present invention are shown.
  • the gray part shows the convex part and the white part shows the concave part.
  • the top view of an example of the ⁇ / 4 type radio wave absorber of this invention is shown.
  • the gray part shows the convex part and the white part shows the concave part.
  • a schematic cross-sectional view of an example of the ⁇ / 4 type radio wave absorber member of the present invention is shown.
  • a schematic cross-sectional view of an example of a molded product with a radio wave absorber of the present invention is shown.
  • the present invention includes a resistance film, a dielectric layer, and a reflective layer, and the dielectric layer has two or more regions having a thickness difference of 15 ⁇ m or more.
  • ⁇ / 4 type radio wave absorber in the present specification, it may be referred to as “ ⁇ / 4 type radio wave absorber of the present invention”. This will be described below.
  • the resistance film is not particularly limited as long as it includes a layer that can function as a resistance layer in the radio wave absorber.
  • the resistance value of the resistance film is not particularly limited.
  • the resistance value (sheet resistance) of the resistance film is, for example, 100 to 800 ⁇ / ⁇ . Within this range, it is more preferably 150 to 750 ⁇ / ⁇ , still more preferably 200 to 600 ⁇ / ⁇ .
  • the resistance value of the resistance film can be measured by the 4-terminal method using a surface resistance meter (MITSUBISHI CHEMICAL ANALYTECH, trade name "Loresta-EP”).
  • the resistance value is determined by the eddy current method using a non-contact resistance tester (product name "EC-80P, manufactured by Napson, or an equivalent product)" when a support or the like described later is laminated and the resistance film cannot be measured directly. Therefore, it is possible to measure from the surface opposite to the resistance film of the support.
  • the thickness of the resistance film is not particularly limited as long as it has a resistance value that can satisfy the characteristics of the present invention.
  • the thickness of the resistance film is, for example, 1 nm or more and 200 nm or less, preferably 2 nm or more and 100 nm or less, and more preferably 2 nm or more and 50 nm or less.
  • the layer structure of the resistance film is not particularly limited.
  • the resistance film may be composed of a single layer of one type, or may be a combination of a plurality of layers of two or more types.
  • the resistance value of the resistance layer is not particularly limited as long as it can satisfy the characteristics of the present invention.
  • the resistance value of the resistance layer is, for example, 100 to 800 ⁇ / ⁇ . Within this range, it is more preferably 150 to 750 ⁇ / ⁇ , still more preferably 200 to 600 ⁇ / ⁇ .
  • the thickness of the resistance layer is not particularly limited as long as it has a resistance value that can satisfy the characteristics of the present invention.
  • the thickness of the resistance layer is, for example, 1 nm or more and 200 nm or less, preferably 2 nm or more and 100 nm or less, and more preferably 2 nm or more and 50 nm or less.
  • the layer structure of the resistance layer is not particularly limited.
  • the resistance layer may be composed of one type of resistance layer alone, or may be a combination of a plurality of types of resistance layers of two or more types.
  • Indium oxide-containing resistance layer examples include a resistance layer containing a resistance layer material such as indium oxide.
  • the resistance layer material preferably contains a material obtained by doping indium oxide with another material (dopant).
  • dopant another material
  • Other materials are not particularly limited, and examples thereof include tin oxide and zinc oxide, and mixtures thereof.
  • indium oxide preferably, indium (III) oxide (In 2 O 3 ) doped with tin (IV) (SnO 2 ) (indium tin oxide) (tin-).
  • ITO indium oxide
  • the SnO 2 content in ITO is preferably 1 to 40% by weight, because the amorphous structure is extremely stable and the fluctuation of the sheet resistance of the resistance layer can be suppressed even in a high temperature and high humidity environment. It is preferably 2 to 35% by weight.
  • the content of the resistance layer material in the resistance layer is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and usually less than 100% by mass. is there.
  • Molybdenum-containing resistance layer As the resistance layer, a resistance 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 preferred, 15% by weight is very preferred, and 16% by weight is most preferred.
  • the upper limit of the molybdenum content is preferably 30% by weight, more preferably 25% by weight, still more preferably 20% by weight, from the viewpoint of facilitating adjustment of the surface resistance value.
  • the resistance layer contains molybdenum
  • nickel and chromium in addition to molybdenum in the resistance layer, a more durable radio wave absorber can be obtained.
  • alloys containing nickel, chromium and molybdenum include Hastelloy B-2, B-3, C-4, C-2000, C-22, C-276, G-30, N, W and X. Various grades can be mentioned.
  • the resistance 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, nickel content of 45% by weight or more, and chromium content of 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 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 resistance layer may contain a metal other than molybdenum, nickel and chromium.
  • a metal include iron, cobalt, tungsten, manganese, titanium and the like.
  • the upper limit of the total content of metals other than molybdenum, nickel and chromium is preferably 45% by weight, more preferably 40, from the viewpoint of durability of the resistance layer. It is by weight%, 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 15% by weight from the viewpoint of the durability of the resistance layer. 1% 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 independently from the viewpoint of the durability of the resistance layer. It is 3% 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 resistance layer. 1% by weight.
  • the resistance layer may contain silicon and / or carbon.
  • the content of 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 resistance film preferably includes a barrier layer.
  • the barrier layer is placed on at least one surface of the resistance layer.
  • the barrier layer will be described in detail below.
  • the barrier layer is not particularly limited as long as it is a layer that can protect the resistance layer and suppress its deterioration.
  • the material of the barrier layer include metal compounds, metalloid compounds, preferably metal or metalloid oxides, nitrides, nitride oxides and the like.
  • 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 element contained in the barrier layer include titanium, aluminum, niobium, cobalt, nickel and the like.
  • Examples of the metalloid element contained in the barrier layer include silicon, germanium, antimony, and bismuth.
  • MO X As the oxide, for example, MO X [in the formula, X is a number satisfying the formula: n / 100 ⁇ X ⁇ n / 2 (n is a valence of a metal or a metalloid), and M is a metal element or It is a metalloid element. ], Examples thereof include compounds represented by.
  • MN y As the above-mentioned nitride, for example, MN y [in the formula, Y is a number satisfying the formula: n / 100 ⁇ Y ⁇ n / 3 (n is a valence of a metal or a metalloid), and M is a metal element or It is a metalloid element. ], Examples thereof include compounds represented by.
  • nitride oxide examples include MO X N y [in the formula, X and Y are n / 100 ⁇ X, n / 100 ⁇ Y, and X + Y ⁇ n / 2 (n is a metal or metalloid valence). ), And M is a metal element or a metalloid element. ], Examples thereof include compounds represented by.
  • the cross section of the layer containing MOx or MOxNy is elementally analyzed by FE-TEM-EDX (for example, "JEM-ARM200F” manufactured by JEOL Ltd.), and MOx or
  • the valence of oxygen atoms can be calculated by calculating X from the elemental ratio of M and O per area of the cross section of the layer containing MOxNy.
  • the cross section of the layer containing MN y or MO x N y is elementalized by FE-TEM-EDX (for example, "JEM-ARM200F” manufactured by JEOL Ltd.).
  • the valence of nitrogen atoms can be calculated by analyzing and calculating Y from the elemental ratio of M and N per area of the cross section of the layer containing MN y or MO x N y.
  • the material of the barrier layer include SiO 2 , SiO x , Al 2 O 3 , MgAl 2 O 4 , CuO, CuN, TiO 2 , TiN, AZO (aluminum-doped zinc oxide) and the like.
  • the thickness of the barrier layer is not particularly limited.
  • the thickness of the barrier layer is, for example, 1 nm or more and 200 nm or less, preferably 1 nm or more and 100 nm or less, and more preferably 1 nm or more and 20 nm or less.
  • 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.
  • the dielectric layer can function as a dielectric for a target wavelength in a radio wave absorber, and is not particularly limited as long as it has two or more regions having a thickness difference of 15 ⁇ m or more.
  • the dielectric layer is not particularly limited, and examples thereof include an adhesive layer, a resin sheet, and a foam layer.
  • the pressure-sensitive adhesive layer is not particularly limited as long as it contains a pressure-sensitive adhesive.
  • the pressure-sensitive adhesive layer may contain components other than the pressure-sensitive adhesive as long as the effects of the present invention are not significantly impaired.
  • the total amount of the resin in the resin sheet is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and usually less than 100% by mass. is there.
  • the adhesive is not particularly limited, and for example, acrylic adhesive, urethane adhesive, polyolefin adhesive, polyester adhesive, vinyl alkyl ether adhesive, polyamide adhesive, rubber adhesive, silicone adhesive. Examples thereof include adhesives and fluorine-based adhesives. Among these, an acrylic pressure-sensitive adhesive is preferable from the viewpoint of high weather resistance.
  • the resin sheet is not particularly limited as long as it is in the form of a sheet containing resin as a material.
  • the resin sheet may contain components other than the resin as long as the effects of the present invention are not significantly impaired.
  • the total amount of the resin in the resin sheet is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and usually less than 100% by mass. is there.
  • the resin is not particularly limited, and is, for example, ethylene vinyl acetate copolymer (EVA), vinyl chloride, urethane, acrylic, acrylic urethane, polyolefin, polyethylene, polypropylene, silicone, polyethylene terephthalate, polyester, polystyrene, polyimide, polycarbonate, polyamide. , Polysulfon, polyether sulfone, synthetic resins such as epoxy, polyisoprene rubber, polystyrene / butadiene rubber, polybutadiene rubber, chloroprene rubber, acrylonitrile / butadiene rubber, butyl rubber, acrylic rubber, ethylene / propylene rubber, silicone rubber, etc. It is preferable to use a rubber material as a resin component. These can be used alone or in combination of two or more.
  • EVA ethylene vinyl acetate copolymer
  • vinyl chloride urethane
  • acrylic acrylic urethane
  • polyolefin polyethylene
  • the dielectric layer may have adhesiveness. Therefore, when a dielectric having no adhesiveness is laminated on another layer by the pressure-sensitive adhesive layer, the combination of the dielectric and the pressure-sensitive adhesive layer becomes a "dielectric layer".
  • the dielectric layer preferably includes an adhesive layer from the viewpoint of easy stacking with the adjacent layer.
  • the relative permittivity of the dielectric layer is not particularly limited.
  • the relative permittivity of the dielectric layer is, for example, 1 to 20, preferably 1 to 15, more preferably 1 to 10, and even more preferably 1 to 5.
  • the relative permittivity of the dielectric layer can be measured by using a network analyzer, a cavity resonator, or the like to measure the relative permittivity at 10 GHz by the cavity resonator perturbation method.
  • the thickness of each of the two or more regions in the dielectric layer is not particularly limited.
  • the thickness of each region of the dielectric layer is, for example, 100 to 1000 ⁇ m, preferably 200 to 800 ⁇ m, more preferably 300 to 700 ⁇ m, and even more preferably 350 to 650 ⁇ m.
  • the thickness of each of the two or more regions of the dielectric layer can be measured by Nikon DIGIMICRO STANDMS-11C + Nikon DIGIMICRO MFC-101.
  • the difference in thickness between two or more regions in the dielectric layer is not particularly limited as long as it is 15 ⁇ m or more, but is, for example, 25 ⁇ m or more, 50 ⁇ m or more, and 100 ⁇ m or more.
  • the difference is preferably 350 ⁇ m or less, more preferably 200 ⁇ m or less, from the viewpoint that the thickness of the absorber can be reduced.
  • the radio wave absorption peak position when the difference in thickness is provided in this way substantially coincides with the radio wave absorption peak position calculated by regarding the area average thickness of the dielectric layer having a step as the thickness of the dielectric layer. Therefore, the difference in thickness, area, and thickness of each of the two or more regions in the dielectric layer is designed according to the target radio wave absorption peak position (that is, the area average thickness of the dielectric layer having the thickness difference). Can be designed).
  • the thickness of the dielectric layer can be measured as follows.
  • the thickness of the dielectric is measured with a thickness gauge (Nikon DIGIMICRO STANDMS-11C + Nikon DIGIMICRO MFC-101 or equivalent).
  • each of the high and low portions is measured at 5 points or more, and the value obtained by subtracting the average thickness of the low portion from the average thickness of the high portion is defined as the thickness difference.
  • the thickness of the dielectric layer in the ⁇ / 4 type radio wave absorber for example, the thickness of the ⁇ / 4 type radio wave absorber is first measured, and the laminated body other than the dielectric layer is formed from the total thickness of the ⁇ / 4 type radio wave absorber. It can be calculated by subtracting the thickness of the layer (for example, resistance film layer, reflective layer, etc.). The measurement is performed at 5 points, and the average value is taken as the thickness.
  • the area average thickness of the body layer is calculated by the formula: (d1 ⁇ A + d2 ⁇ B + d3 ⁇ C) / 100.
  • at least one of the difference between d1 and d2, the difference between d2 and d3, and the difference between d3 and d1 is 25 ⁇ m or more.
  • the area average thickness of the dielectric layer is preferably 100 to 800 ⁇ m, more preferably 200 to 800 ⁇ m because it is excellent in radio wave absorption (particularly radio wave absorption for high frequency radio waves).
  • the thickness can be appropriately adjusted according to the frequency of the radio wave targeted by the radio wave absorber and the dielectric constant of the dielectric.
  • the area average thickness of the dielectric layer is preferably 350 ⁇ m or more. It is 740 ⁇ m or less, more preferably 415 ⁇ m or more and 680 ⁇ m or less.
  • the thickness of each of the two or more regions in the dielectric layer is preferably 80 to 120%, more preferably 80 to 120%, based on the area average thickness of the dielectric layer of 100%, from the viewpoint that the total thickness of the absorber can be reduced. Is 90 to 110%, more preferably 95 to 105%.
  • the area of each of the two or more regions in the dielectric layer is not particularly limited.
  • the area is, for example, 0.1 cm 2 or more, 0.3 cm 2 or more, 1 cm 2 or more, 3 cm 2 or more, 10 cm 2 or more, 30 cm 2 or more, or 100 cm 2 or more.
  • the upper limit of the area is not particularly limited, for example, 10000 cm 2 or less, 3000 cm 2 or less, 1000 cm 2 or less, 300 cm 2 or less, 100 cm 2 or less, 30 cm 2 or less, or 10 cm 2 or less.
  • the width of each of the two or more regions in the dielectric layer is not particularly limited, and can be appropriately adjusted depending on the wavelength of the radio wave to be absorbed and the irradiation range.
  • the width is, for example, 0.1 cm or more, or 1 cm or more.
  • the upper limit of the width is not particularly limited, and is, for example, 10000 cm or less, 3000 cm or less, 1000 cm or less, 300 cm or less, 100 cm or less, 30 cm or less, or 10 cm or less.
  • the layer structure of the dielectric layer is not particularly limited.
  • the dielectric layer may be composed of one type of single dielectric layer, or may be a combination of two or more types of dielectric layers.
  • a three-layer structure dielectric layer composed of a non-adhesive dielectric and adhesive layers arranged on both sides thereof, a one-layer structure dielectric layer composed of an adhesive dielectric, and the like can be mentioned.
  • the method for forming two or more regions having different thicknesses in the dielectric layer is not particularly limited, and for example, a method using a known method can be adopted. For example, a method of laminating a plurality of dielectric layers having different thicknesses so as not to overlap each other, a method of laminating a dielectric layer having a uniform thickness, and a method of further laminating a dielectric layer on a part thereof can be mentioned.
  • the reflective layer is not particularly limited as long as it can function as a radio wave reflecting layer in the radio wave absorber.
  • the reflective layer is not particularly limited, and examples thereof include a metal film.
  • the metal film is not particularly limited as long as it is a layer containing metal as a material.
  • the metal film may contain a component other than the metal as long as the effect of the present invention is not significantly impaired.
  • the total amount of the metal in the metal film is, for example, 30% by mass or more, preferably 50% by mass or more, more preferably 75% by mass or more, still more preferably 80% by mass or more, still more preferably 90% by mass or more. , Particularly preferably 95% by mass or more, very preferably 99% by mass or more, and usually less than 100% by mass.
  • the metal is not particularly limited, and examples thereof include aluminum, copper, iron, silver, gold, chromium, nickel, molybdenum, gallium, zinc, tin, niobium, and indium. Further, a metal compound such as ITO can also be used as a material for the metal film. These may be one kind alone or a combination of two or more kinds.
  • the thickness of the reflective layer is not particularly limited.
  • the thickness of the reflective layer is, for example, 1 ⁇ m or more and 500 ⁇ m or less, preferably 2 ⁇ m or more and 200 ⁇ m or less, and more preferably 5 ⁇ m or more and 100 ⁇ m or less.
  • the layer structure of the reflective layer is not particularly limited.
  • the reflective layer may be composed of one type of single reflective layer, or may be a combination of a plurality of two or more types of reflective layers.
  • the ⁇ / 4 type radio wave absorber of the present invention preferably further has a support.
  • the support is not particularly limited as long as it is in the form of a sheet.
  • the support is not particularly limited, and examples thereof include a resin base material.
  • the resin base material is a base material containing resin as a material, and is not particularly limited as long as it is in the form of a sheet.
  • the resin base material may contain components other than the resin as long as the effects of the present invention are not significantly impaired.
  • titanium oxide or the like may be contained from the viewpoint of adjusting the relative permittivity.
  • the total amount of the resin in the resin base material 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 resin is not particularly limited, and is, for example, a polyester resin such as polyethylene terephthalate (PET), polyethylene naphthalate, or modified polyester, a polyolefin such as a polyethylene (PE) resin, a polypropylene (PP) resin, a polystyrene resin, or a cyclic olefin resin.
  • a polyester resin such as polyethylene terephthalate (PET), polyethylene naphthalate, or modified polyester
  • a polyolefin such as a polyethylene (PE) resin, a polypropylene (PP) resin, a polystyrene resin, or a cyclic olefin resin.
  • vinyl resins such as polyvinyl chloride and vinylidene chloride, polyvinyl acetal resins such as polyvinyl butyral (PVB), polyether ether ketone (PEEK) resin, polysulfone (PSF) resin, polyether sulfone (
  • polyester resin is preferable, and polyethylene terephthalate is more preferable, from the viewpoint of productivity and strength.
  • the relative permittivity of the support is not particularly limited.
  • the relative permittivity of the support is, for example, 1 to 20, preferably 1 to 15, more preferably 1 to 10, and even more preferably 1 to 5.
  • the thickness of the support is not particularly limited.
  • the thickness of the support is, for example, 5 ⁇ m or more and 500 ⁇ m or less, preferably 10 ⁇ m or more and 300 ⁇ m or less, and more preferably 20 ⁇ m or more and 300 ⁇ m or less.
  • the layer structure of the support is not particularly limited.
  • the support may be composed of one type of support alone, or may be a combination of a plurality of types of two or more types of supports.
  • each layer is arranged in the order in which the radio wave absorption performance can be exhibited.
  • the resistance film, the dielectric layer, and the reflective layer are arranged in this order.
  • the ⁇ / 4 type radio wave absorber of the present invention has a support, as an example, the support, the resistance film, the dielectric layer, and the reflective layer are arranged in this order.
  • the ⁇ / 4 type radio wave absorber of the present invention may include other layers in addition to the support, the resistance film, the dielectric layer, and the reflective layer.
  • the other layer may be placed on the surface of either the support, the resistance film, the dielectric layer, and the reflective layer, respectively.
  • Examples of the other layer include an adhesive layer arranged on the surface of the reflective layer opposite to the dielectric layer side.
  • This pressure-sensitive adhesive layer makes it possible to easily attach the ⁇ / 4 type radio wave absorber of the present invention by another member (for example, a device in an automobile). From this viewpoint, in the ⁇ / 4 type radio wave absorber of the present invention, it is preferable that the pressure-sensitive adhesive layer is arranged on the surface of the reflective layer opposite to the dielectric layer side.
  • the adhesive is not particularly limited, and for example, acrylic adhesive, urethane adhesive, polyolefin adhesive, polyester adhesive, vinyl alkyl ether adhesive, polyamide adhesive, rubber adhesive, silicone adhesive. Examples thereof include adhesives and fluorine-based adhesives.
  • the radio wave absorption peak position of the ⁇ / 4 type radio wave absorber of the present invention is preferably 10 GHz or more and 150 GHz or less, more preferably 20 GHz or more and 120 GHz or less, still more preferably 30 GHz or more and 110 GHz or less, still more preferably 55 GHz or more and 110 GHz or less, particularly. It is preferably 55 GHz or more and 90 GHz or less, and more preferably 70 GHz or more and 90 GHz or less.
  • the radio wave absorption amount of the ⁇ / 4 type radio wave absorber of the present invention at 60 to 90 GHz is preferably 15 dB or more, more preferably 20 dB or more, still more preferably 25 dB or more.
  • the radio wave absorption amount of the ⁇ / 4 type radio wave absorber of the present invention at 70 to 90 GHz is preferably 15 dB or more, more preferably 20 dB or more, still more preferably 25 dB or more.
  • the radio wave absorption peak position and the radio wave absorption amount are measured by the following method.
  • Network analyzer MS4647B manufactured by Anritsu
  • free space material measuring device BD1-26 free space material measuring device BD1-26.
  • a radio wave absorption measuring device is configured using A (manufactured by Keycom), and the radio wave absorption amount of the ⁇ / 4 type radio wave absorber obtained by using this radio wave absorption measuring device in the 55 to 90 GHz band is based on JIS R1679. Can be measured.
  • the ⁇ / 4 type radio wave absorber is set so that the radio wave incident direction is vertical incident and incident from the resistance film side.
  • the ⁇ / 4 type radio wave absorber of the present invention On the outermost surface of the ⁇ / 4 type radio wave absorber of the present invention (at least one of the surface on the resistance film layer side and the surface on the reflection layer side), another layer follows the step of the dielectric layer, and the above-mentioned dielectric layer A structure that reflects the difference in thickness and structure of the above can be formed. That is, it is preferable that the ⁇ / 4 type radio wave absorber of the present invention has two or more regions having a thickness difference of 15 ⁇ m or more on the outermost surface (the surface on the resistance film layer side or the surface on the reflection layer side).
  • the difference in thickness is more preferably 25 ⁇ m or more, still more preferably 50 ⁇ m or more, and more preferably 100 ⁇ m or more.
  • the thickness difference is preferably 350 ⁇ m or less, more preferably 200 ⁇ m or less, from the viewpoint that the thickness of the absorber can be reduced.
  • the area and the like of each region are the same as those of each region in the above-mentioned dielectric layer. Further, as the resistance film, the reflective film and the dielectric, the same ones as described above can be used.
  • the thickness difference can be measured as follows. Measure the thickness of the ⁇ / 4 type radio wave absorber with a thickness meter (Nikon DIGIMICRO STANDMS-11C + Nikon DIGIMICRO MFC-101 or equivalent). Five or more points are measured at each of the high and low portions of the step of the ⁇ / 4 type radio wave absorber, and the value obtained by subtracting the average thickness of the low portion from the average value of the thickness of the high portion is defined as the thickness difference.
  • a structure reflecting the step of the dielectric layer can be formed on the outermost surface of the ⁇ / 4 type radio wave absorber of the present invention (at least one of the surface on the resistance film layer side and the surface on the reflection layer side).
  • the resistance film layer or the reflective layer may not be formed on the raised portion (step surface in the step-terrace structure) of the step.
  • a step formed by following the step of the dielectric layer by another layer is formed.
  • the ⁇ / 4 type radio wave absorber of the present invention can be provided with various properties / functions (for example, surface design, wiring space due to dents, drip property, etc.) utilizing the step on the surface.
  • the step may be formed on both the resistance film layer side surface and the reflection layer side surface.
  • the ⁇ / 4 type radio wave absorber of the present invention On the outermost surface of the ⁇ / 4 type radio wave absorber of the present invention (at least one of the surface on the resistance film layer side and the surface on the reflection layer side), another layer follows the step of the dielectric layer, and the above-mentioned dielectric layer A structure that reflects the difference in thickness and structure of the above can be formed. That is, the ⁇ / 4 type radio wave absorber of the present invention preferably has a surface roughness Rz of 7.5 ⁇ m or more on its outermost surface (at least one of the surface on the resistance film layer side and the surface on the reflection layer side).
  • the present invention includes a resistance film, a dielectric layer, and a reflection layer, and has a surface roughness Rz on the outermost surface (at least one of the surface on the resistance film layer side and the surface on the reflection layer side).
  • the present invention relates to a ⁇ / 4 type radio wave absorber having a thickness of 7.5 ⁇ m or more.
  • the Rz is more preferably 15 ⁇ m or more, still more preferably 25 ⁇ m or more, even more preferably 50 ⁇ m or more, and particularly preferably 100 ⁇ m or more.
  • the upper limit of the Rz is not particularly limited, but is preferably 350 ⁇ m or less, more preferably 200 ⁇ m or less, from the viewpoint that the thickness of the absorber can be reduced.
  • the step may be formed on both the resistance film layer side surface and the reflection layer side surface. Further, as the resistance film, the reflective film and the dielectric, the same ones as described above can be used.
  • the surface roughness Rz on the outermost surface (the surface on the resistance film layer side or the surface on the reflection layer side) of the ⁇ / 4 type radio wave absorber can be measured as follows. It can be measured by a surface roughness meter (manufactured by Tokyo Seimitsu Co., Ltd., trade name Surfcom 1800A or its equivalent) based on JIS B0601 (2001).
  • the ⁇ / 4 type radio wave absorber of the present invention can be obtained according to or according to various methods, for example, a known manufacturing method, depending on its configuration. For example, it can be obtained by a method including a step of sequentially laminating a resistance film, a dielectric layer, and a reflective layer on a support.
  • the stacking method is not particularly limited.
  • the resistance film can be formed 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.
  • the sputtering method is not particularly limited, and examples thereof include DC magnetron sputtering, high frequency magnetron sputtering, and ion beam sputtering.
  • the sputtering apparatus may be a batch system or a roll-to-roll system.
  • the dielectric layer and the reflective layer can be laminated by utilizing, for example, the adhesiveness of the dielectric layer.
  • the present invention includes a resistance film and a dielectric layer, and the dielectric layer has two or more regions having a thickness difference of 15 ⁇ m or more. It relates to a member for a type 4 radio wave absorber.
  • the member for the ⁇ / 4 type radio wave absorber preferably further includes a support.
  • the ⁇ / 4 type radio wave absorber member is a member for forming a ⁇ / 4 type radio wave absorber by arranging it in contact with an adherend (housing or the like) that can function as a reflective layer.
  • the support, resistance film, dielectric layer, and other configurations are the same as those described for the ⁇ / 4 type radio wave absorber of the present invention.
  • the ⁇ / 4 type radio wave absorber of the present invention has the ability to absorb unnecessary electromagnetic waves, and is therefore suitable as a radio wave countermeasure member in, for example, optical transceivers, next-generation mobile communication systems (5G), short-range wireless transfer technology, and the like. Can be used for. In addition, it should also be used for the purpose of suppressing radio wave interference and reducing noise in intelligent transportation systems (ITS) that communicate information between automobiles, roads, and people, and millimeter-wave radars used in automobile collision prevention systems. Can be done.
  • ITS intelligent transportation systems
  • the present invention relates to, in one embodiment, a molded product and a molded product with a radio wave absorber, which comprises the ⁇ / 4 type radio wave absorber of the present invention attached to the molded product.
  • the molded product include members used in the above-mentioned various uses.
  • the method of attaching the ⁇ / 4 type radio wave absorber of the present invention to the molded product is not particularly limited, and examples thereof include a method of attaching via an adhesive and a method of attaching with a fixture.
  • a preferred example of a molded product with a radio wave absorber is a millimeter wave radar.
  • the frequency of the radio wave targeted by the ⁇ / 4 type radio wave absorber of the present invention is preferably 10 GHz or more and 150 GHz or less, more preferably 20 GHz or more and 120 GHz or less, still more preferably 30 GHz or more and 110 GHz or less, still more preferably 55 GHz or more and 110 GHz or less. It is particularly preferably 55 GHz or more and 90 GHz or less, and more preferably 70 GHz or more and 90 GHz or less.
  • the ⁇ / 4 type radio wave absorber of the present invention is installed so as to have two or more regions in which the difference in thickness of the above-mentioned dielectric layer is 15 ⁇ m or more within the irradiation range of the target radio wave. Is preferable. Further, the ⁇ / 4 type radio wave absorber of the present invention has the shape of each region and the installation location of the radio wave absorber so as to have the area average thickness of the above-mentioned dielectric layer within the range irradiated with the target radio wave. It is preferable to adjust.
  • an adhesive tape double-sided adhesive tape used for the dielectric layer was manufactured as follows. Acrylic with a width of 10 cm, a length of 10 cm, a thickness of 500 ⁇ m and a relative permittivity of 2.5 on one side of an acrylic double-sided adhesive tape having a width of 1 cm, a length of 10 cm, a thickness of 100 ⁇ m and a relative permittivity of 2.5. Double-sided adhesive tapes were laminated with a distance of 1 cm each.
  • a ⁇ / 4 type radio wave absorber was manufactured as follows.
  • a white polyethylene terephthalate (PET) film (relative permittivity 3.4) having a thickness of 125 ⁇ m was prepared.
  • Sputtering was carried out using Hastelloy C-276 as a target, introduced at an output of 0.4 kW and an Ar gas flow rate of 100 sccm, and adjusted to a pressure of 0.12 Pa.
  • the dielectric layer made of the adhesive tape was laminated on the formed resistance film with the stepped side facing the resistance film side, and the reflective layer made of copper having a thickness of 12 ⁇ m was laminated on the dielectric layer. Then, a ⁇ / 4 type radio wave absorber was obtained.
  • Example 2 An acrylic double-sided adhesive tape having a thickness of 100 ⁇ m and a relative permittivity of 3.6 was laminated on one side of an acrylic double-sided adhesive tape having a thickness of 400 ⁇ m and a relative permittivity of 3.6 so as to form a stripe.
  • a ⁇ / 4 type radio wave absorber was obtained in the same manner as in Example 1.
  • Example 4 An acrylic double-sided adhesive tape having a thickness of 100 ⁇ m and a relative permittivity of 3.6 was laminated on one side of an acrylic double-sided adhesive tape having a thickness of 400 ⁇ m and a relative permittivity of 3.6 so as to form a stripe. At this time, the width of the stripes was laminated so that the ratio of the non-laminated portion to the laminated portion was 4: 1.
  • a ⁇ / 4 type radio wave absorber was obtained in the same manner as in Example 1.
  • Example 5 An acrylic double-sided adhesive tape having a thickness of 150 ⁇ m and a relative permittivity of 3.0 was laminated on one side of an acrylic double-sided adhesive tape having a thickness of 450 ⁇ m and a relative permittivity of 3.0.
  • a ⁇ / 4 type radio wave absorber was obtained in the same manner as in Example 1.
  • Example 7 An acrylic double-sided adhesive tape having a thickness of 150 ⁇ m and a relative permittivity of 3.0 was laminated on one side of an acrylic double-sided adhesive tape having a thickness of 450 ⁇ m and a relative permittivity of 3.0. At this time, the width of the stripes was laminated so that the ratio of the non-laminated portion to the laminated portion was 4: 1.
  • a ⁇ / 4 type radio wave absorber was obtained in the same manner as in Example 1.
  • Example 8 A dielectric made of polycarbonate having a thickness of 400 ⁇ m and a relative permittivity of 2.6 and a dielectric made of polycarbonate having a thickness of 500 ⁇ m and a relative permittivity of 2.6 on one side of an acrylic double-sided adhesive tape having a thickness of 30 ⁇ m and a relative permittivity of 3.0.
  • the bodies were arranged alternately in a striped pattern. Further, an acrylic double-sided adhesive tape having a thickness of 30 ⁇ m and a relative permittivity of 3.0 is laminated on it, and a region having a thickness of 460 ⁇ m (area is 50% of the total) and a region having a thickness of 560 ⁇ m (area is 50% of the total) are formed.
  • Example 11 A dielectric made of polycarbonate having a thickness of 300 ⁇ m and a relative permittivity of 2.6 and a dielectric made of polycarbonate having a thickness of 500 ⁇ m and a relative permittivity of 2.6 on one side of an acrylic double-sided adhesive tape having a thickness of 30 ⁇ m and a relative permittivity of 3.0. After cutting the body into small pieces of 10 mm square, they were arranged alternately in a checkered pattern.
  • an acrylic double-sided adhesive tape having a thickness of 30 ⁇ m and a relative permittivity of 3.0 is laminated on the tape, and the region has a thickness of 360 ⁇ m (the area is 50% of the total) and the region has a thickness of 560 ⁇ m (the area is 50% of the total).
  • a ⁇ / 4 type radio wave absorber was obtained in the same manner as in Example 1.
  • Example 12 On one side of an acrylic double-sided adhesive tape with a thickness of 30 ⁇ m and a relative permittivity of 3.0, a dielectric made of polycarbonate having a thickness of 200 ⁇ m and a relative dielectric constant of 2.6 and a dielectric made of polycarbonate having a thickness of 300 ⁇ m and a relative dielectric constant of 2.6 After cutting the body, a dielectric made of polycarbonate having a thickness of 400 ⁇ m and a relative permittivity of 2.6, and a dielectric made of polycarbonate having a thickness of 500 ⁇ m and a relative permittivity of 2.6 into 50 mm squares, one piece each having a thickness of 50 mm square. was arranged so as to form a 100 mm square.
  • an acrylic double-sided adhesive tape with a thickness of 30 ⁇ m and a relative permittivity of 3.0 is laminated on it, and a region with a thickness of 260 ⁇ m (area is 25% of the total), a region with a thickness of 360 ⁇ m (area is 25% of the total), and a thickness.
  • a ⁇ / 4 type radio wave absorber was obtained in the same manner as in Example 1.
  • the ⁇ / 4 type radio wave absorbers of Examples 1 to 8 exhibited good radio wave absorption characteristics in a target wavelength range even though the dielectric layer had a relatively large step.
  • the radio wave absorption peak position when the step is provided almost coincides with the radio wave absorption peak position calculated by regarding the area average thickness of the dielectric layer having the step as the thickness of the dielectric layer. That is, it was found that the radio wave absorption peak position when the step is provided can be controlled based on the respective thicknesses of the thick region and the thin region of the dielectric layer and their area ratios.
  • a step was formed on the surface on the support side following the step of the dielectric layer. From this, when the dielectric layer is positively provided with a step, various properties and functions (for example, surface design, wiring space due to dents, drip property, etc.) can be imparted by utilizing the step on the surface. Do you get it.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
  • Laminated Bodies (AREA)

Abstract

La présente invention aborde le problème de la fourniture d'une nouvelle technologie pour commander les caractéristiques d'absorption d'onde d'un absorbeur d'onde λ/4. Compte tenu de la connaissance que la position de pic d'absorption d'onde dans le cas où les étages sont fournis à une couche diélectrique peut être commandée sur la base des épaisseurs respectives et du rapport de surface des zones épaisses et des zones minces de la couche diélectrique, la présente invention concerne un absorbeur d'onde λ/4 qui comprend une couche diélectrique étagée.
PCT/JP2020/035970 2019-09-25 2020-09-24 ABSORBEUR D'ONDE λ/4 WO2021060353A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5927597A (ja) * 1982-08-06 1984-02-14 ティーディーケイ株式会社 電波吸収体
JPH0384997A (ja) * 1989-08-28 1991-04-10 Akzo Kashima Ltd 電波吸収体
JPH057093A (ja) * 1991-06-28 1993-01-14 Osaka Gas Co Ltd 電波吸収体
JP2002176285A (ja) * 2000-12-05 2002-06-21 Em Techno:Kk 電波吸収体及び電波吸収方法
JP2009193739A (ja) * 2008-02-13 2009-08-27 Mitsubishi Paper Mills Ltd 導電性材料前駆体および導電性材料

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5927597A (ja) * 1982-08-06 1984-02-14 ティーディーケイ株式会社 電波吸収体
JPH0384997A (ja) * 1989-08-28 1991-04-10 Akzo Kashima Ltd 電波吸収体
JPH057093A (ja) * 1991-06-28 1993-01-14 Osaka Gas Co Ltd 電波吸収体
JP2002176285A (ja) * 2000-12-05 2002-06-21 Em Techno:Kk 電波吸収体及び電波吸収方法
JP2009193739A (ja) * 2008-02-13 2009-08-27 Mitsubishi Paper Mills Ltd 導電性材料前駆体および導電性材料

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