Electromagnetic wave absorbing sheet and method of manufacturing the same and electronic device using the same

• US 9,832,917 B2
• Filed: 12/27/2013
• Issued: 11/28/2017
• Est. Priority Date: 12/27/2012
• Status: Active Grant

• Current Assignee: Amosense Co., Ltd.
• Original Assignee: Amosense Co., Ltd.
• Inventors: Jang, Kil Jae, Lee, Dong Hoon, Kim, Ki Chul
• Primary Examiner(s): Bernatz, Kevin M
• Application Number:
  US14/652,960
• Publication Number:
  US 20150342099A1
• Time in Patent Office: 1,432 Days
• Field of Search: None
• CPC Class Codes: B32B 15/04 comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material next to a bituminous or tarry layer B32B11/08; next to a water-setting substance layer B32B13/06; next to a glass layer B32B17/061; next to a cellulosic plastic layer B32B23/042
• CPC Class Codes: B32B 2307/208 Magnetic, paramagnetic
• CPC Class Codes: B32B 2307/702 Amorphous
• CPC Class Codes: B32B 2307/704 Crystalline
• CPC Class Codes: B32B 7/12 using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: H01F 1/16 in the form of sheets H01F1/147 takes precedence
• CPC Class Codes: H01F 1/34 non-metallic substances, e.g. ferrites
• CPC Class Codes: H01Q 1/52 Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure absorbing means H01Q17/00
• CPC Class Codes: H01Q 17/00 Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
• CPC Class Codes: H05K 9/0075 Magnetic shielding materials
• CPC Class Codes: H05K 9/0081 Electromagnetic shielding materials, e.g. EMI, RFI shielding H05K9/0003 takes precedence
• CPC Class Codes: Y10T 156/10 Methods of surface bonding and/or assembly therefor
• CPC Class Codes: Y10T 428/25 Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• CPC Class Codes: Y10T 428/26 Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
• CPC Class Codes: Y10T 428/2804 Next to metal
• CPC Class Codes: Y10T 428/2848 Three or more layers
• CPC Class Codes: Y10T 428/32 Composite [nonstructural laminate] of inorganic material having metal-compound-containing layer and having defined magnetic layer

Abstract

Provided are an electromagnetic wave absorbing sheet which is a thin film and a low cost and has an excellent electromagnetic wave absorbing rate, a method of manufacturing the same, and an electronic device using the same. The electromagnetic wave absorbing sheet includes: at least one layer thin-film magnetic sheet which is separated into a plurality of fine pieces; a protective film that is adhered on one surface of the thin-film magnetic sheet; and a double-sided tape that is adhered on the other surface of the thin-film magnetic sheet.

Claims

1. An electromagnetic wave absorbing sheet comprising:

at least one layer thin-film magnetic sheet which is broken and separated into a plurality of broken pieces having gaps between the broken pieces by a flake-processing, the broken pieces having a size of no larger than 3 mm;

a protective film that is adhered on one surface of the thin-film magnetic sheet, wherein the protective film includes a first adhesive layer provided on the one surface of the thin-film magnetic sheet, and a portion of the first adhesive layer is filled into the gaps; and

a double-sided tape that is adhered on the other surface of the thin-film magnetic sheet, wherein the double-sided tape includes a second adhesive layer provided on the other surface of the thin-film magnetic sheet, and a portion of the second adhesive layer is filled into the gaps,

wherein the thin-film magnetic sheet has an imaginary part permeability component of not less than 50 at 300 MHz.

2. The electromagnetic wave absorbing sheet of claim 1, wherein the thin-film magnetic sheet is made of a Fe-based amorphous alloy, a Co-based amorphous alloy or a nanocrystalline alloy.

3. The electromagnetic wave absorbing sheet of claim 2, wherein the Fe-based amorphous alloy is formed of a Fe—

Si—

B or Fe—

Si—

B—

Co alloy, and the nanocrystalline alloy is formed of a Fe—

Si—

B—

Cu—

Nb alloy.

4. The electromagnetic wave absorbing sheet of claim 1, wherein a heat treatment is performed in a range of 300°

C. to 600°

C. when the thin-film magnetic sheet is made of a Fe-based amorphous alloy.

5. The electromagnetic wave absorbing sheet of claim 1, wherein a heat treatment is performed in a range of 300°

C. to 700°

C. when the thin-film magnetic sheet is made of a nanocrystalline alloy.

6. The electromagnetic wave absorbing sheet of claim 1, wherein the thin-film magnetic sheet is made of an amorphous ribbon stacked in one to four layers.

7. The electromagnetic wave absorbing sheet of claim 1, wherein the thin-film magnetic sheet is made of an amorphous ribbon, and the amorphous ribbon is formed to have a thickness of 15 to 35 μ

m.

8. The electromagnetic wave absorbing sheet of claim 1, wherein the electromagnetic wave absorbing sheet is made of a 30 μ

m to 300 μ

m thick, and is used in a frequency band of 400 MHz to 10 GHz.

9. The electromagnetic wave absorbing sheet of claim 1, wherein a power loss which is defined as a ratio (P_loss/P_in) of lost power (P_loss) and input power (P_in) is not less than 60% in a frequency band of 1 GHz to 8 GHz.

10. A portable electronic device comprising the electromagnetic wave absorbing sheet according to claim 1.