Ferrite material, ferrite film formed thereof, and radio frequency identification tag with ferrite film

Abstract

A ferrite material is disclosed, consisting of an oxide metal composition, the metal composition having the formula of FeaNibZncCod, where: a+b+c+d=3.0; 2.1≦a≦2.7; 0≦b≦0.4; 0≦c≦0.4; and 0.1≦d≦0.5. A ferrite film is made of the ferrite material. Preferably, the ferrite film is formed by a ferrite plating method to have a thickness of 30 μm or less and an aspect ratio of 30 or more. The ferrite film is arranged or provided in the vicinity of an antenna conductor of a radio frequency identification tag. The ferrite film may be in direct contact with the antenna conductor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an RFID tag according to an embodiment of the present invention;

FIG. 2 is an exploded, perspective view showing the RFID tag of FIG. 1;

FIG. 3 is a view schematically showing a film formation apparatus that is used for forming a ferrite film shown in FIG. 2;

FIG. 4 is a top plan view schematically showing an arrangement for evaluating the RFID tag of FIG. 1, wherein a dipole antenna of a reader is now shown;

FIG. 5 is a side view schematically showing the arrangement of FIG. 4 that includes the dipole antenna, too;

FIG. 6 is a graph showing a result of evaluation in accordance with the arrangement of FIGS. 4 and 5;

FIG. 7 is a perspective view showing a modification of the foregoing RFID tag of FIG. 1; and

FIG. 8 is a perspective view showing another modification of the foregoing RFID tag of FIG. 1.

Claims

1. A ferrite material consisting of an oxide metal composition, the metal composition having the formula of FeaNiaZnbCod, where: a+b+c+d=3.0;2.1≦a≦2.7;0≦b≦0.4;0≦c≦0.4; and0.1≦d≦0.5.

2. The ferrite material according to claim 1, having a natural resonance frequency of 1 GHz or more.

3. The ferrite material according to claim 1 or 2, having a tan δ(=μ″/μ′) of 1.0 or less at 900 MHz.

4. The ferrite material according to claim 3, having a resistivity of 0.1 Ωcm or more.

5. A ferrite film made of the ferrite material according to claim 1.

6. The ferrite film according to claim 5, formed by a ferrite plating method.

7. The ferrite film according to claim 5 or 6, having a thickness of 30 μm or less.

8. The ferrite film according to claim 7, having an aspect ratio of 30 or more.

9. A radio frequency identification (RFID) tag, comprising: a main member including an antenna conductor; andthe ferrite film according to claim 5 or 6, the ferrite film being in contact with the main member or being arranged in the vicinity of the main member.

10. The RFID tag according to claim 9, wherein the main member further comprising a tag base, the tag base having a top surface, the antenna conductor being provided on the top surface of the tag base.

11. The RFID tag according to claim 10, wherein the tag base has a bottom surface, and the ferrite film is in contact with the bottom surface of the tag base.

12. The RFID tag according to claim 9, wherein the ferrite film is in direct contact with the antenna conductor.

13. The RFID tag according to claim 9, further comprising a supporter, the ferrite film being formed on the supporter.

14. The ferrite material according to claim 1 or 2, having a resistivity of 0.1 Ωcm or more.

15. A ferrite film made of the ferrite material according to claim 2.

16. The ferrite film according to claim 15, formed by a ferrite plating method.