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

Patent metadata

Field	Value
Publication number	US-9832917-B2
Application number	US-201314652960-A
Country	US
Kind code	B2
Filing date	Dec 27, 2013
Priority date	Dec 27, 2012
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

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.

First claim

The invention claimed is:

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 μm.

8. The electromagnetic wave absorbing sheet of claim 1 , wherein the electromagnetic wave absorbing sheet is made of a 30 μm to 300 μm 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 .

Assignees

• Amosense Co Ltd

Inventors

• Jang Kil Jae
• Lee Dong Hoon
• Kim Ki Chul

Classifications

• H01Q17/00

  Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems · CPC title

• H05K9/0075 Primary

  Magnetic shielding materials · CPC title

• B32B7/12 Primary

  using interposed adhesives or interposed materials with bonding properties · CPC title

• B32B2307/208

  Magnetic, paramagnetic · CPC title

• H01F1/34

  non-metallic substances, e.g. ferrites · CPC title