Magnetic sheet for radio frequency identification antenna, method of manufacturing the same, and radio frequency identification antenna using the same

Abstract

Provided are a magnetic sheet for use in a radio frequency identification (RFID) antenna, an RFID antenna including the magnetic sheet, and a method of manufacturing the magnetic sheet, in which the magnetic sheet includes an amorphous alloy selected from the group consisting of Fe—Si—B, Fe—Si—B—Cu—Nb, Fe—Zr—B and Co—Fe—Si—B. The magnetic sheet is made by laminating amorphous alloy ribbons made of an amorphous alloy between magnetic sheet layers formed of alloy powder including at least one amorphous alloy and then compression-molding the amorphous alloy ribbons, to thereby control microcrack of the amorphous alloy ribbons and enhance characteristic of an end-product. The magnetic sheet is also thin, and has an excellent magnetic permeability, and a simple manufacturing process.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a magnetic sheet for use in a radio frequency identification (RFID) antenna, a method of manufacturing the same, and a radio frequency identification (RFID) antenna using the magnetic sheet. More particularly, the present invention relates to a magnetic sheet for use in a radio frequency identification (RFID) antenna, a method of manufacturing the same, and a radio frequency identification (RFID) antenna using the magnetic sheet, in which the magnetic sheet is a mono-layer structure which is made of alloy powder including at least one amorphous alloy, or a multilayer structure which is formed by laminating an amorphous alloy ribbon made of an amorphous alloy between magnetic sheet layers and compression-molding the same. [0003] 2. Description of the Related Art [0004] Recently, a radio frequency identification (RFID) system communicating data between a transponder including an integr...

AI Technical Summary

Benefits of technology

[0018] The inventors have proved the fact that these inventors could manufacture a magnetic sheet having the thin and uniform thickness of 0.35 mm or less in comparison with an existing metal sheet at the low cost with the minimum process, since the magnetic sheet includes an amorphous alloy selected from the group consisting of Fe—Si—B, Fe—Si—B—Cu—Nb, Fe—Zr—B and Co—Fe—Si—B, and an alloy ribbon is directly manufactured into a thin film type of 0.03 mm or less.

[0019] Moreover, in the case of the magnetic sheet made of the amorphous alloy, the saturationmagnetic flux density 0.57 T-1.6 T is much higher than the saturation magnetic flux density 0.45 T of the existing ferrite, and the magnetic permeability is high even in the thin thickness. Accordingly, the inventors have discovered the fact that the magnetic flux which modulates in the RFID communications can be effectively focused on the transponder antenna coil. In addition, the inventors has discovered the fact that the electromagnetic waves of 0.9 GHz and 1.9 GHz frequency band having no concern with the RFID communications, and the several gigahertz (GHz) band which is the harmonic component of standard communications electromagnetic wave bands, during the communications process of the cellular phone, without having the metal layer, in comparison with the ferrite sheet, can be blocked effectively. The conventional problem can be solved in the case that the magnetic sheet is used as the absorber for the RFID antenna of the portable device including the mobile phone.

[0021] To solve the above problems, it is another object of the present invention to provide a magnetic sheet for use in a radio frequency identification (RFID) antenna, an RFID antenna including the magnetic sheet, and a method of manufacturing the magnetic sheet, in which the magnetic sheet is made by laminating amorphous alloy ribbons made of an amorphous alloy between magnetic sheet layers formed of alloy powder including at least one amorphous alloy and then compression-molding the amorphous alloy ribbons, to thereby provide a multilayer structure of a simple process of manufacturing a thin magnetic sheet and having an excellent magnetic permeability.

[0030] In this case, since the amorphous alloy ribbon laminated between the mixed sheets causes the microcrack to occur through a rolling or a press of the sheet thereby dropping down a loss, the frequency characteristic being the disadvantage of the amorphous alloy ribbon can be enhanced, and a complicated process which is slit in order to use an existing amorphous alloy ribbon. In this case, it is possible that the capacity of a battery is extended in a battery pack of the same thickness or the thickness of the battery pack is made into an ultra thin type, since inductance necessary for RFID communications can be effectively obtained.

Problems solved by technology

Accordingly, if a magnetic material having a higher magnetic permeability is employed as a material of the absorber sheet for the tag antenna, a data communication distance is increased and an error probability of data can be lowered.

In the conventional technology, it is very difficult to tune the LC resonance circuit since an inductance deviation of the transponder antenna is serious due to the non-uniformity of the thickness of these ferrites.

Moreover, the non-uniformity exceeding the error range of the thickness may cause difficulty of an installation when a magnetic sheet is attached in a battery pack space, and an error occurs in the process of the formation and transmission of binary code data during the mutual transmission process of data, to thereby make a very high inferiority ratio, as well.

Accordingly, an amount of the power consumption increases.

In this case, the communications distance is excessively shortened, that is, the quality of performance is not implemented.

However, since the powder manufactured in the form of a spherical shape should be pulverized into the nano size and made to be flat, the manufacturing process is complicated and the original material is expansive.

Moreover, since these conventional materials have the problem that an effective cross-sectional area of the material representing the magnetic property cannot be secured as the thickness of the conventional materials is thinner, it has a limitation in heightening the inductance necessary for securing the distance of the RFID communications.

Also, since a thickness of the conventional materials is uneven during manufacturing, the deviation of inductance becomes serious.

However, the magnetic permeability of the magnetic sheet is not high even in the thin thickness below 0.35 mm.

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