Ferrite green sheet, sintered ferrite sheet, ferrite composite sheet comprising the same, and conductive loop antenna module

Patent metadata

Field	Value
Publication number	US-9847577-B2
Application number	US-201314649568-A
Country	US
Kind code	B2
Filing date	Dec 2, 2013
Priority date	Dec 6, 2012
Publication date	Dec 19, 2017
Grant date	Dec 19, 2017

Abstract

Disclosed are a ferrite green sheet comprising a pattern formed in a top surface of the ferrite green sheet, a sintered ferrite sheet, a ferrite composite sheet comprising the same, and a conductive loop antenna module. The pattern comprises a plurality of grooves, each groove has a width W and a rounded shape bottom having a radius of curvature of R, wherein a ratio of W to R (W:R) is in the range of 1:0.1 to 1:0.5.

First claim

What is claimed is:

1. A ferrite green sheet comprising:
a pattern formed in a top surface of the ferrite green sheet, the pattern comprising a plurality of grooves, each groove having a width W and a rounded shape bottom having a radius of curvature R,
wherein a ratio (W:R) of W to R is in the range of 1:0.1 to 1:0.5.

2. The ferrite green sheet of claim 1 , wherein the pattern is a lattice-type pattern.

3. The ferrite green sheet of claim 1 , wherein the pattern is formed by coating a ferrite slurry comprising a ferrite powder, a solvent, a dispersing agent, a binder, and a plasticizer, on a patterned peel liner and drying the ferrite slurry.

4. The ferrite green sheet of claim 3 , wherein the ferrite powder is a powder of soft spinel ferrite.

5. A sintered ferrite sheet comprising:
a pattern formed in a top surface thereof,
wherein the pattern comprises a plurality of grooves, and
each of the grooves has a round-shaped bottom, which has a radius of curvature R, and a width W, wherein a ratio (W:R) of W to R is in a range of 1:0.1 to 1:0.5.

6. The sintered ferrite sheet of claim 5 , having a magnetic permeability with a real part ur′ and imaginary part ur″ of not less than 80 and not greater than 20, respectively, at 13.56 MHz.

7. The sintered ferrite sheet of claim 5 , having a magnetic permeability with a real part ur′ and imaginary part ur″ of not less than 80 and not greater than 100, respectively, at 13.56 MHz.

8. The sintered ferrite sheet of claim 5 ,
wherein the pattern is a lattice-type pattern, and
the pattern is formed by coating a ferrite slurry including a ferrite powder, a solvent, a dispersing agent, a binder, and a plasticizer on a patterned peel liner and drying the ferrite slurry,
wherein the ferrite powder is a powder of Ni—Zn—Cu-based spinel ferrite, and the sintered ferrite sheet has a magnetic permeability with a real part ur′ and imaginary part ur″ of not less than 80 and not greater than 20, respectively, at 13.56 MHz, or the ferrite powder is a powder of Mg—Zn—Cu-based spinel ferrite, and the sintered ferrite sheet has a magnetic permeability with a real part ur′ and imaginary part ur″ of not less than 80 and not greater than 100, respectively, at 13.56 MHz.

9. A ferrite composite sheet comprising the sintered ferrite sheet of claim 5 .

10. The ferrite composite sheet of claim 9 , comprising:
an adhesive layer formed on the sintered ferrite sheet;
a protective film formed on the adhesive layer; and
a conductive layer provided on the opposite side of the sintered ferrite sheet from the adhesive layer.

11. The ferrite composite sheet of claim 10 , wherein at least one adhesive layer comprises an air-containing portion.

12. The ferrite composite sheet of claim 10 , wherein at least one of the adhesive layers comprises an embossed coating film.

13. The ferrite composite sheet of claim 9 , comprising:
a first adhesive layer formed on the sintered ferrite sheet;
a protective film formed on the adhesive layer;
a conductive layer formed provided on the opposite side of the sintered ferrite sheet from the first adhesive layer; and
a second adhesive layer provided under the conductive layer.

14. A conductive loop antenna module for use in a wireless communication media and a wireless communication medium processing device comprising:
a magnetic member comprising the sintered ferrite sheet of claim 5 ;
a conductive loop antenna provided on one surface of the magnetic member; and
a conductive layer provided on the opposite surface of the magnetic member from the conductive loop antenna.

15. The conductive loop antenna module of claim 14 , wherein the conductive
layer has a thickness of 50 μm or less and a surface electric resistance 3Ω/□ or less.

16. A ferrite green sheet comprising:
a pattern formed in a top surface of the ferrite green sheet, the pattern comprising an elongated recess in the sheet having a width W at the top surface and a round-shaped bottom having a radius of curvature R, wherein a ratio (W:R) of W to R is in a range from about 1:0.1 to about 1:0.5.

Assignees

• 3M Innovative Properties Co

Inventors

• Hur Eun-Kwang
• Suh Jung-Ju
• Cho Seungah
• Choi Suk-Won

Classifications

• H04B5/43

  Antennas · CPC title

• H04B5/20

  characterised by the transmission technique; characterised by the transmission medium · CPC title

• C04B2235/945

  Products containing grooves, cuts, recesses or protusions · CPC title

• C04B2235/608

  Green bodies or pre-forms with well-defined density · CPC title

• C04B2235/6025

  Tape casting, e.g. with a doctor blade · CPC title