KR100775763B1 - Tag for RFID and Fabricating method thereof - Google Patents

Abstract

The present invention relates to an RFID tag and a method of manufacturing the same, wherein a reflective electrode is composed of a first electrode and a second electrode spaced apart from each other by engaging each other, and the first electrode and the second electrode are connected at each electrode, and are terminated. After forming so as to face the mutually spaced apart and mutually spaced apart, and to determine the presence or absence of the reflected wave at the reflective electrode according to whether the conductive ink is formed in the mutually spaced areas of the extension of the first electrode and the second electrode Allows you to code the information yourself.

Surface Acoustic Wave, Tag, Reflective Wave, Conductive Ink

Description

RDF tag and manufacturing method {Tag for RFID and Fabricating method

1 is a view schematically showing an RFID tag using a conventional surface acoustic wave (SAW).

2 is a view showing a reflective electrode in an RFID tag using surface acoustic waves.

3A is a diagram illustrating a reflective electrode when a reflected wave is generated.

3B is a view showing a reflective electrode when the reflected wave disappears.

4A is a diagram showing a reflective electrode when the reflected wave of the present invention is generated.

4B is a view showing a reflective electrode when the reflected wave of the present invention disappears.

5a to 5d are views showing an embodiment of a method of manufacturing the RFID tag of the present invention.

Explanation of symbols on the main parts of the drawings

510: piezoelectric substrate 520: interdigital converter

530: reflective electrode 540: support

550: antenna

The present invention relates to a radio frequency identification tag (RFID) and a method of manufacturing the same.

RFID (Radio Frequency IDentification) is a technology that reads information by wirelessly recognizing objects, and is a key technology that enables silent commerce, a key concept of ubiquitous computing, which is drawing attention recently.

RFID, which stores various information such as production, distribution, price, etc., and reads it through a wireless reader on a smart chip that emits powerful radio frequency, can store more information than barcode. The recognition distance is also very long, 1.5 ~ 27m, and it is possible to penetrate obstacles except metal.

Due to these many advantages, RFID has been spotlighted as a next-generation technology following the bar code that is widely used, and its application field is also being applied to various fields such as logistics, distribution, security, and access control.

An RFID system is called a tag and is a transponder that stores unique information, and a transceiver (reader or reader) that functions to read and decrypt. It consists of host computer (server), network, and application program.

Here, the RFID tag is composed of an IC chip, an antenna, and adhesive materials having functions such as data storage, processing, and modulation, and refers to an apparatus for transmitting and receiving predetermined data with an external reader.

RFID tags with IC chips have a fairly long read range that is reliable, but they are expensive and are limited to individual applications where the range of use can be economically justified.

Therefore, recently, a chipless RFID tag that can be manufactured at low cost without having an IC chip is attracting attention, and a representative one of them is an RFID tag using surface acoustic waves.

Here, Surface Acoustic Wave (SAW) refers to a wave in which energy is concentrated and transmitted near the surface of a medium, and two comb-shaped metal plates are alternately arranged on both sides of a piezoelectric substrate, and electrical signals are transmitted in one direction. When input, surface acoustic waves are generated on the piezoelectric substrate.

In other words, when a metal electrode is formed on a substrate having high piezoelectricity and a voltage is applied, the surface of the substrate is temporarily warped. This action causes a physical wave.

1 is a view schematically showing an RFID tag using a conventional surface acoustic wave (SAW).

As shown here, the RF signal transmitted from the reader 10 is converted into a surface acoustic wave signal in the interdigital transducer (IDT) 20 to advance the substrate 30.

That is, the interdigital converter 20 converts the electrical signal transmitted from the reader 10 into a mechanical signal.

The surface acoustic wave signal traveling through the substrate 30 is reflected back to the interdigital transducer 20 through the reflective electrodes 40 positioned at a predetermined distance from the interdigital transducer 20, and the reflected surface acoustic wave signal is again inter In the digital converter 20 is converted into an RF signal.

In more detail, when the interdigital converter 20 generates a surface acoustic wave signal, the surface acoustic wave signal travels along the substrate 30 until it encounters the reflective electrode 40 and reflects a portion of the signal.

The non-reflected portion of the surface acoustic wave signal then continues along the substrate 30 to generate additional reflection signals from all subsequent reflection electrodes 40 to produce a fully modulated reflection response inherent to the RFID tag. .

The interdigital converter 20 then converts the fully modulated reflection response back into an electrical signal that is returned to the reader 10 by the antenna 50.

In this case, the interdigital converter 20 converts a mechanical signal into an electrical signal, and the RF signal converted by the interdigital converter 20 is read by the reader 10 via the antenna 50.

Here, the intensity of the signal read out from the reader 10 changes depending on the presence or absence of the reflective electrode at each position on the substrate 30.

In other words, the presence or absence of the reflected surface acoustic wave signal is determined according to the presence or absence of the reflective electrode 40 at a predetermined interval on the substrate 30, and is read by the reader 10 according to the presence or absence of the reflected surface acoustic wave signal. The strength of the signal changes.

The reader 10 can read the information recorded in the tag by determining whether the reflected signal is 1 and 0. That is, the method of recording information in the RFID tag using the surface acoustic wave is the same as determining the presence or absence of the reflective electrode at each position on the substrate.

The conventional method of arranging reflective electrodes on RFID tags using surface acoustic waves uses a process of manufacturing reflective electrodes at all possible positions and then removing some reflective electrodes according to information to be recorded.

However, this process is only possible in a factory producing RFID tags, and there is a problem in that the user cannot directly record information.

Accordingly, an object of the present invention comprises a first electrode and a second electrode spaced apart from each other while engaging the reflective electrodes in the RFID tag, wherein the first electrode and the second electrode are connected to each electrode, and the ends are opposed to each other, and are spaced apart from each other. It is to provide an RFID tag for coding the information to be recorded according to whether the conductive ink is formed in the mutually spaced areas of the extension portion of the first electrode and the second electrode by providing the extended portion, and a manufacturing method thereof.

An embodiment of the RFID tag according to the present invention includes a piezoelectric substrate bonded to an upper portion of the support, an interdigital converter formed on the piezoelectric substrate, and converting an RF signal into a surface acoustic wave and converting the surface acoustic wave into an RF signal. And reflecting the surface acoustic waves converted by the interdigital transducer back to the interdigital transducer, and having a first electrode and a second electrode that are engaged with and spaced apart from each other, wherein the first electrode and the second electrode are connected at each electrode and are terminated. And a plurality of reflective electrodes including the plurality of reflection electrodes facing each other and spaced apart from each other, and an antenna for inputting an RF signal to the interdigital converter and outputting the RF signal converted by the interdigital converter to the outside. do.

Embodiment of the method of manufacturing an RFID tag of the present invention, the interdigital transducer is formed on the piezoelectric substrate, the first electrode and the second electrode is engaged with and spaced apart from each other, wherein the first electrode and the second electrode is each electrode Forming a plurality of reflective electrodes connected to each other and having opposite ends spaced apart from each other and bonded to each other, bonding the piezoelectric substrate to a support, and inputting an RF signal through the interdigital converter on the support; And forming an antenna for outputting the RF signal converted by the interdigital converter to the outside, and forming conductive ink in mutually spaced areas of the extension portions of the first electrode and the second electrode according to information to be coded. Characterized in that comprises a.

Hereinafter, the RFID tag of the present invention and a manufacturing method thereof will be described in detail with reference to FIGS. 2 to 5.

2 is a diagram illustrating a reflective electrode in an RFID tag using surface acoustic waves. As shown in the drawing, the reflective electrode is disposed to be spaced from and interlocked with the first electrode 100 and the first electrode 100 having a plurality of finger-shaped electrodes 110 (Finger Electrode), a plurality of finger-shaped It consists of a second electrode 150 having an electrode (110) of.

The reflective electrodes are arranged at regular intervals on the substrate, and the finger-shaped electrodes 110 in the reflective electrodes have a constant period T, so as to have a half wavelength period of the surface acoustic wave propagating through the substrate. do.

As such, when the finger-shaped electrodes 110 have a period of half the wavelength of the surface acoustic waves propagating through the substrate, the surface acoustic waves are incident on the reflective electrode and then the surface acoustic waves are incident on the reflective electrode when they are reflected. It comes out with the same wavelength.

On the other hand, depending on whether or not the short (Short) of the reflective electrode disposed at a predetermined interval on the substrate, it is possible to eliminate or generate the reflected wave by the reflective electrode, which will be described with reference to FIG.

3A is a diagram illustrating a reflective electrode when a reflected wave is generated. As shown in the drawing, the reflective electrode includes a plurality of split finger electrodes 210 having a plurality of split finger electrodes 210 and a plurality of split finger electrodes. And a second electrode 250 engaged with the first electrode 200 and spaced apart from each other.

In addition, the split finger electrodes 210 are disposed to have a constant period T. The split finger electrode 210 has a period of 1/4 wavelength of the wavelength of the surface acoustic wave incident on the reflective electrode. do.

As such, when the split finger electrodes 210 have a quarter wavelength period of the surface acoustic wave, the surface acoustic wave is incident on the reflective electrode, and then the surface acoustic wave is incident to the reflective electrode when reflected. It comes out with a wavelength.

3B is a diagram showing a reflective electrode when the reflected wave disappears. As shown in the drawing, the reflective electrode is electrically shorted with the first electrode 200 and the second electrode 250.

As described above, when the first electrode 200 and the second electrode 250 that are opposed to each other with a plurality of split finger electrodes 210 having a quarter wavelength period of the incident surface acoustic wave are shorted, the reflective electrode In the surface acoustic waves, mutual interference interferes with each other and no reflection occurs.

That is, since the phase of the surface acoustic wave reflected from the split finger electrode positioned first and the surface acoustic wave reflected from the split finger electrode positioned next to each other are reversed to cancel each other, the reflected wave is not generated at the reflected electrode. Will not.

As described above, the reflected wave may be generated or eliminated depending on whether the reflective electrode is short-circuited, which may be considered as a switching concept.

4 is a view showing a switching method according to the reflective electrode of the present invention. FIG. 4A illustrates a case in which the switch is off, and FIG. 4B illustrates a case in which the switch is on.

As shown in FIG. 4A, the reflective electrode of the present invention has a plurality of split finger electrodes 310, and a split finger electrode 315 at one end thereof is formed to extend longer than another split finger electrode. An electrode 300,

The plurality of split finger electrodes 360 are arranged to be engaged with the first electrode 300, and extend from the body to mutually extend the split finger electrode 315 longer than the first electrode 300. It is composed of a second electrode 350 having an extended portion 365 formed to face apart.

Here, the plurality of split finger electrodes 310 and 360 are arranged to have a quarter wavelength period of surface acoustic waves, and when the surface acoustic waves are incident on the reflective electrode, the wavelengths are the same as the wavelength of the incident surface acoustic waves. The reflected wave having is generated.

That is, in this case, when the switch is turned off, the first electrode 300 and the second electrode 350 are not short-circuited to generate the reflected wave.

However, as shown in FIG. 4B, when the switch is turned on, the split finger electrode 315 longer than the first electrode 300 and the split finger electrode 315 of the second electrode 350 are shown. The conductive ink 400 is formed in the mutually spaced areas of the extension part 365 formed to be spaced apart from each other to face the first electrode 300 and the second electrode 350.

In this case, even when surface acoustic waves enter the reflective electrode due to a short circuit between the first electrode 300 and the second electrode 350, they cancel each other out of the interference and thus do not generate the reflected wave.

Here, although the split finger electrode 315 positioned at one end of the first electrode 300 has an extended portion formed longer than the other electrodes, the first electrode 300 is the same as the extension portion 365 of the second electrode. It may extend from the body portion of the) to be spaced apart from each other and the extension 365 of the second electrode, it may be formed to extend to face.

That is, the extension portions of the first electrode 300 and the second electrode 350 may be formed in various ways, and the extension portions of each electrode may be formed to be spaced apart from each other and face each other so that the conductive ink may be formed on the spaced portions of the extension portions. The short circuit of the reflective electrode may be determined depending on whether it is formed.

In the present invention, the split finger electrode 315 at one end of the first electrode 300 is formed longer than the other split finger electrode 310, and the extension portion 365 is formed on the second electrode 300. The extended portion 365 is formed to be spaced apart from each other and opposed to the split finger electrode 315 formed longer than the first electrode, the split finger electrode 315 formed longer than the first electrode and It is determined whether the first electrode 300 and the second electrode 350 are short-circuited according to whether the conductive ink 400 is formed in the mutually spaced areas of the extension part 365.

According to whether the first electrode 300 and the second electrode 350 are short-circuited, the presence or absence of the reflected wave at the reflection electrode is determined. In the reader, the presence or absence of the reflected signal is determined to be 1 and 0, so that the tag The recorded information can be read.

For example, in the case of an RFID tag having 64 bits of information, 64 such reflective electrodes are formed on a substrate and spaced apart from each other by extension portions of the first electrode and the second electrode of the corresponding reflective electrode according to the information to be coded. By dropping the conductive ink in the area to dissipate the reflected wave, information can be easily written to the RFID tag.

5A to 5D are views illustrating an embodiment of a method of manufacturing the RFID tag of the present invention.

First, the interdigital converter 520 for converting an RF signal into a surface acoustic wave having a predetermined wavelength on the piezoelectric substrate 510 and the surface acoustic wave converted by the interdigital converter 520 are again interdigital converter 520. Reflecting electrode 530 for reflecting is formed (FIG. 5A).

That is, after the metal and the photoresist are sequentially stacked on the piezoelectric substrate 510, the interdigital converter 520 and the reflective electrode 530 patterns are formed on the photoresist.

After etching the metal using the patterned photoresist as a mask, the remaining photoresist is removed to form the interdigital converter 520 and the reflective electrode 530 on the piezoelectric substrate 510.

Although one chip is shown and described here, it is actually manufactured on a wafer basis and then diced into separate chips.

Next, the piezoelectric substrate 510 on which the interdigital converter 520 and the reflective electrode 530 are formed is placed on a sheet 540 made of any one material selected from plastic, ceramic, metal, and glass. After arranging, the sheet 540 is bonded to the sheet 540 (FIG. 5B).

Subsequently, the information to be recorded on the RFID tag is coded using inkjet printing technology, and then an antenna 550 is formed (FIG. 5C).

That is, the conductive ink is formed in the corresponding region of the reflective electrode according to the information to be coded by the inkjet printing technology to determine whether each reflective electrode is shorted.

In this case, when the conductive ink is formed to short-circuit the reflective electrode, no reflected wave is generated in the reflective electrode, which is determined as 0 by the reader.

When the reflective electrode is not short-circuited because the conductive ink is not formed, the reflected wave is generated at the reflective electrode, which is determined as 1 by the reader.

Accordingly, the information of the RFID tag may be different depending on whether conductive ink is formed in the mutually spaced areas of the first electrode and the second electrode of the reflective electrode to short-circuit the reflective electrode.

In this case, the antenna 550 is formed using the conductive ink. In this case, the antenna 550 may be implemented in various forms such as a dipole antenna and a helical antenna.

Thereafter, the conductive ink is heat-treated to have sufficient conductivity, and then the sheet is cut for each RFID tag to form a separate RFID tag (FIG. 5D).

That is, by removing the solvent (Solvent) of the conductive ink through the heat treatment, the metal powders of the conductive ink are connected to each other to have sufficient conductivity.

On the other hand, while the present invention has been shown and described with respect to specific preferred embodiments, various modifications and variations of the present invention without departing from the spirit or field of the invention provided by the claims below It will be readily apparent to one of ordinary skill in the art that it can be used.

As described above, according to the present invention, the reflective electrodes are configured to be spaced apart from each other by engaging the first electrode and the second electrode, and the first and second electrodes are connected to each electrode, and the ends thereof are spaced apart from each other. By providing the extension, the user can directly code the information to be recorded according to whether the conductive ink is formed in the mutually spaced areas of the first electrode and the second electrode.

In addition, since the fabrication of the antenna used in the RFID tag is also formed using an inkjet printer, the manufacturing process is simplified and the manufacturing cost can be reduced.

Claims (7)

A piezoelectric substrate bonded to the upper portion of the support; An interdigital converter formed on the piezoelectric substrate and converting an RF signal to a surface acoustic wave and converting the surface acoustic wave to an RF signal; The surface acoustic wave converted by the interdigital transducer is reflected back to the interdigital transducer and is composed of a first electrode and a second electrode which are engaged with and spaced apart from each other, wherein the first electrode and the second electrode are connected at each electrode, A plurality of reflective electrodes having extensions extending opposite to each other and spaced apart from each other; And And an antenna for inputting an RF signal to the interdigital converter and outputting the RF signal converted by the interdigital converter to the outside. The reflective electrode is an RFID tag, characterized in that for electrically shorting by connecting the mutually spaced areas of the extension of the first electrode and the second electrode with a conductive ink. The method of claim 1, The first electrode and the second electrode has a plurality of split finger electrodes, the extension of the first electrode RFID tag, characterized in that extending from the split finger electrode located at one end. delete The method of claim 1, The antenna is an RFID tag, characterized in that made of conductive ink. An interdigital transducer is formed on the piezoelectric substrate, and the first and second electrodes are engaged with and spaced apart from each other, and the first and second electrodes are connected at each electrode, and the ends are opposed to each other, and the extension parts are spaced apart from each other. Forming a plurality of reflective electrodes; Bonding the piezoelectric substrate to a support; Forming an antenna on the support part to input an RF signal to the interdigital converter and output the RF signal converted by the interdigital converter to the outside; And And forming a conductive ink in a spaced apart region of the extension of the first electrode and the second electrode according to the information to be coded. The method of claim 5, The antenna is a method of manufacturing an RFID tag, characterized in that formed with a conductive ink. The method according to claim 5 or 6, After the conductive ink is formed, the method of manufacturing an RFID tag further comprising the step of heat-treating the conductive ink.

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