Radio wave-absorbing laminate film, production method therefor, and element including same

Patent metadata

Field	Value
Publication number	US-2021227730-A1
Application number	US-201915734079-A
Country	US
Kind code	A1
Filing date	May 30, 2019
Priority date	Jun 6, 2018
Publication date	Jul 22, 2021
Grant date	—

Abstract

A radio wave-absorbing laminate film in which both the top surface and the bottom surface have superior transmission attenuation properties and reflection attenuation capabilities in extremely high-frequency wave bands and higher, and which exhibits excellent radio wave absorption properties even when extremely thin; a production method for the film; and an element containing the film. A radio wave-absorbing laminate film having radio wave-absorbing layers, the radio wave-absorbing laminate film including a center layer, two substrate layers, and two radio wave-absorbing layers, the center layer containing at least one metal layer, and the two substrate layers being laminated on both surfaces of the center layer. With regard to each of the two substrate layers, the radio wave-absorbing layer is laminated on the surface opposite to the center layer, and, the two substrate layers are the same or different, the two radio wave-absorbing layers are the same or different, and at least one of the radio wave-absorbing layers contains a magnetic body.

First claim

1 . A radio wave absorbing laminate film comprising:
a radio wave absorbing layer; the radio wave absorbing laminate film comprising a core layer, two substrate layers, and two radio wave absorbing layer, the core layer comprising at least one metal layer, the two substrate layers being laminated on both surfaces of the core layer, the radio wave absorbing layer being laminated on a surface opposite to the core layer for each of the two substrate layers, the two substrate layers being either the same as or different from each other, the two radio wave absorbing layers being either the same as or different from each other, and at least one of the radio wave absorbing layers comprising a magnetic substance.

2 . The radio wave absorbing laminate film according to claim 1 , wherein
at least one surface of the radio wave absorbing laminate film has a peak at which an absolute value of transmission attenuation is 10 dB or more and an absolute value of reflection attenuation is 10 dB or more within a frequency band of 30 GHz or more and 300 GHz or less.

3 . The radio wave absorbing laminate film according to claim 1 , wherein the radio wave absorbing laminate film has a thickness of 1000 μm or less.

4 . The radio wave absorbing laminate film according to claim 1 , wherein the magnetic substance comprises at least one selected from the group consisting of epsilon-type iron oxide, barium ferrite magnetic substance, and strontium ferrite magnetic substance.

5 . The radio wave absorbing laminate film according to claim 4 , wherein the epsilon-type iron oxide is at least one selected from the group consisting of an ε-Fe 2 O 3 crystal; and a crystal of which crystalline structure and space group are the same as those of the ε-Fe 2 O 3 crystal, in which a part of Fe sites in the ε-Fe 2 O 3 crystal is substituted by an element M other than Fe, and which is represented by a formula ε-M x Fe 2-x O 3 wherein x is 0 or more and 2 or less.

6 . A method for producing the radio wave absorbing laminate film according to claims 1 to 5 , the method comprising:
(a1) performing formation of a laminated product at least twice comprising the radio wave absorbing layer and the substrate layer through formation of the radio wave absorbing layer on the substrate layer, thereby obtaining at least two laminated products; and
(b1) laminating a surface of the substrate layer of the laminated product onto each of both surfaces of the core layer.

7 . A method for producing the radio wave absorbing laminate film according to claim 1 , the method comprising:
(a2) laminating the substrate layer onto each of both surfaces of the core layer; and (b2) forming the radio wave absorbing layer on each of the two substrate layers laminated on the core layer.

8 . The method according to claim 6 , wherein the radio wave absorbing layer is formed by applying a paste comprising the magnetic substance onto the substrate layer.

9 . An element comprising the radio wave absorbing laminate film according to claim 1 .

10 . The method according to claim 7 , wherein the radio wave absorbing layer is formed by applying a paste comprising the magnetic substance onto the substrate layer.

Assignees

• Univ Tokyo
• Tokyo Ohka Kogyo Co Ltd

Inventors

• Ohkoshi Shin-Ichi
• Namai Asuka
• YOSHIKIYO Marie
• Asai Takahiro
• Kuwahara Masaru

Classifications

• H01F1/37

  in a bonding agent · CPC title

• H01F1/348

  Hexaferrites with decreased hardness or anisotropy, i.e. with increased permeability in the microwave (GHz) range, e.g. having a hexagonal crystallographic structure · CPC title

• B32B15/082

  comprising vinyl resins; comprising acrylic resins · CPC title

• H05K9/0084 Primary

  comprising a single continuous metallic layer on an electrically insulating supporting structure, e.g. metal foil, film, plating coating, electro-deposition, vapour-deposition · CPC title

• B32B25/08

  of synthetic resin · CPC title