CN110544818A - Conductive ink composition and manufacturing method for making antenna of radio frequency identification tag - Google Patents

Abstract

The invention provides a conductive ink composition for manufacturing an antenna of a radio frequency identification tag and a manufacturing method thereof, wherein the ink composition comprises the following components: the graphite-structure-containing sheet-shaped conductive carbon material, the conductive filler, the dispersant and the solvent are characterized in that the ink composition can be coated on the surface of a fiber base material in a printing or ink-jet printing mode according to the shape of the antenna to form a conductive layer, part of the conductive layer penetrates into pores among fibers of the fiber base material to be attached to the fiber base material, and the fiber base material and the conductive layer form an antenna structure of a radio frequency identification tag without an adhesive (binder-free); the ink composition does not contain an insulating adhesive, so that the conductivity of the antenna structure can be improved, and the resistance and the manufacturing cost can be reduced.

Description

Conductive ink composition and manufacturing method for making antenna of radio frequency identification tag

technical field

The present invention relates to radio frequency identification technology (Radio Frequency Identification, RFID), in particular to a conductive ink composition for making an antenna of a radio frequency identification tag and a manufacturing method of the antenna.

Background technique

The radio frequency identification system includes two parts: a reader (Reader) and a radio frequency identification tag (also known as an electronic tag). The radio frequency identification tag is mainly composed of an IC chip and an antenna. Generally, the common RFID tags are passive tags. The antenna senses the electromagnetic waves emitted by the reader, converts the electromagnetic waves into electric current to activate the IC chip, and then the IC chip returns the pre-stored data to the reader to complete the identification. The radio frequency identification system is classified into low frequency tags (LH, 125 or 134.2KHz), high frequency tags (HF, 13.56MHz), ultra high frequency tags (UHF, 868 to 956MHz) and microwave tags (Microwave, 2.45G) according to the frequency range of electromagnetic waves. Hz), generally speaking, the higher the frequency, the longer the receiving distance and the faster the speed.

The efficiency with which the antenna converts electromagnetic waves into electric current determines the performance of RFID, and the conversion efficiency depends on the antenna design and conductivity. Known antenna manufacturing methods for radio frequency identification tags include copper foil or aluminum foil etching and screen printing. The advantages of copper (aluminum) foil etching include low resistance, high precision, and good performance, but the process is complicated, the production time is long, the cost is high, the use of substrates is limited, and many highly polluting agents such as etching solutions and cleaning agents must be used. Liquid, its manufacturing process is not environmentally friendly. The screen printing method is a fast and cheap method. It directly uses conductive ink to print on the substrate, which has less pollution and since it does not contain an etching process, there are many substrates to choose from. The disadvantage is that the electronic performance of the antenna is not as good as that of the etching method; such as unstable resistance, low conductivity, and poor adhesion. The performance improvement depends on the characteristics of the conductive ink, so the advantages and popularization of the printing method are limited by the price and performance of the conductive ink. At present, metal is the main conductive substance in conductive ink. The commonly used metals are copper and silver, but copper is easy to oxidize, and the price of silver is high, which affects the performance of conductive ink and keeps the price high. The adhesion of metal is also a problem. Since the metal cannot form a film on the substrate by itself, the adhesion of metal conductive ink depends entirely on the adhesive added to the conductive ink, but most of the adhesive is an insulator, which affects the conductivity of the ink. Adhesion The addition of additives makes it difficult to balance both adhesion and resistivity.

Known conductive inks that can be used to make antennas by printing methods, for example: in the published US Patent 2012/027736A1, it is disclosed that the conductive material composition of a conductive ink contains at least one polymer adhesive to achieve good adhesion properties, and contains additional conductive substances such as metals, metal oxides, etc., and its sheet resistance ranges from 0.001 to 500 ohm/sq.

In addition, in the published U.S. Patent 2004/0175515A1, it is proposed that the conductive ink composed of sheet materials can be applied to radio frequency identification through letterpress and gravure printing; polymers and resins are also used as adhesives, and the conductive materials are as follows: Carbon black, metal and metal oxide are the main components, and the sheet resistance is relatively poor at around 200ohm/sq. In the approved U.S. Patent 7017822, it is proposed to mix metal and resin and make wires by molding. The bonding of wires and substrates is still made of resin or molded to the resin substrate. The conductive material is mainly stainless steel. Carbon material is used as filler, and its sheet resistance can reach between 5 and 25 ohm/sq. In the approved Taiwan invention patent I434456 "Method for making RFID antenna with non-woven lava fiber paper substrate", it is proposed to print the antenna with ink containing metal ions, and then reduce the metal by electroless plating. The material is non-woven lava fiber paper, the manufacturing process is complicated and metal is still the main conductive substance. In the published Chinese patent CN101921505B, a conductive ink for radio frequency identification is proposed. The ink material uses a mixture of silver nanowires and silver nanoparticles as a conductive filler, and uses 2 to 10% epoxy resin, but silver The high price of nanowires will increase the manufacturing cost of conductive ink.

The published Chinese patent CN103436099 proposes a composite conductive ink containing flaky silver powder, graphene, and graphite flakes, wherein the silver powder is used as the conductive material for the majority, and the film-forming resin also accounts for 5 to 30% by weight. In addition, as shown in Table 1, in other graphene composite conductive ink patents, all disclosures point out the need for conductive inks containing different amounts of polymer binders. Although the polymer adhesive can effectively increase the adhesion of the conductive printing layer, at the same time, the non-conductive characteristic will also affect the conductivity of the overall printing layer. Therefore, in this case, a polymer adhesive-free conductive ink composition for an RFID tag antenna and a method for manufacturing the antenna will be proposed.

Table 1. The composition and formula of graphene-based conductive ink disclosed by different patents will be listed in full.

Contents of the invention

In order to solve the above-mentioned problems of the known conductive ink, the present invention proposes a conductive ink composition for making an antenna of a radio frequency identification tag, which can be used for printing the antenna of the radio frequency identification tag.

The conductive ink composition used for making the antenna of the radio frequency identification tag of the present invention comprises: sheet-shaped conductive carbon material containing graphite structure, conductive filler, dispersant and solvent.

The manufacturing method of the antenna of the radio frequency identification tag of the present invention comprises: preparing a kind of porous fibrous substrate; preparing a conductive ink composition, and the conductive ink composition comprises: sheet-like conductive carbon material containing graphite structure, conductive filler, A dispersant and a solvent; the conductive ink composition is coated on the surface of the porous fibrous substrate according to the shape of the antenna; the solvent of the conductive ink composition is evaporated by thermal drying to form the conductive ink composition on the surface of the porous fibrous substrate A conductive layer is formed, and part of the conductive layer penetrates into the pores between the fibers of the porous fibrous substrate and adheres to the porous fibrous substrate.

An embodiment of the manufacturing method of the antenna structure of the present invention includes a rolling step of rolling the conductive layer attached to the surface of the porous fiber substrate to a compression ratio of 50-90% of the original thickness.

Among them, a preferred embodiment of the conductive ink composition includes: a sheet-shaped conductive carbon material containing a graphite structure, a conductive filler, a dispersant and a solvent. Wherein, the conductive filler includes other shapes of conductive carbon materials, conductive metal particles, conductive oxides, and conductive polymers.

Wherein, the conductive carbon material includes any one or a combination of graphene, graphite, carbon nanotubes, carbon nanospheres, and conductive carbon black.

Wherein, the conductive metal particles include platinum, gold, palladium, ruthenium, silver, copper, nickel, zinc, or any combination or alloy of more than one.

Wherein, the conductive oxide includes any one or a combination of palladium oxide or ruthenium oxide.

Wherein, the conductive polymer includes any one or a combination of polythiophenes, polypyrroles, polyacetylenes, and polyaniline derivatives.

In the carbon material that adopts sheet-like structure in conductive ink composition, the carbon material of sheet-like structure can stack into irregular fluffy structure, and because the conductive ink composition (the conductive ink composition that contains the carbon material of sheet-like structure Basically, it is a kind of conductive paste) without polymer adhesive in it, and the sheet-like loose structure can be compacted by further rolling treatment, and the van der Waals force of the surface molecular layer of the carbon material with the sheet-like structure can be used to make each other tightly combined. Because there is no insulating and non-conductive polymer binder in the laminated conductive carbon layer, a coating with lower conductivity can be obtained compared to conventional conductive pastes containing polymer binders. In addition to the above-mentioned general use of sheet-like carbon materials as conductive fillers, this case further proposes to take advantage of the characteristics of sheet-like carbon material stacked coatings to form dense layers after rolling, and use sheet-like carbon materials as conductive fillers. Bonding material to grab other conductive fillers. The method is to add other conductive fillers into the conductive ink composition without polymer binder, so that other conductive fillers are dispersed in the loosely stacked sheet-like carbon network structure; The network structure formed by the material is tightly compacted, and other conductive fillers are tightly grasped to form a conductive layer without polymer adhesives, and the antenna of the radio frequency identification tag is made of this high-density Conductive layers of molecular adhesives.

From the above, it can be understood that the conductive ink composition of the radio frequency identification tag of the present invention does not contain an insulating adhesive, which can improve the conductivity of the conductive ink, and the antenna made by applying the conductive ink composition to the surface of the porous fiber substrate The structure has the effect of reducing resistance and production cost, and the combination of the conductive paste made of the conductive ink composition and the porous fiber substrate can further improve the density and conductivity of the conductive layer through a rolling process.

Details about other functions and embodiments of the present invention are described as follows with reference to the accompanying drawings.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments described in this application. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is the sectional structure diagram of the antenna of the radio frequency identification tag of the present invention;

Fig. 2 is a microscopic schematic diagram of the structure of Fig. 1 at position II, showing a schematic diagram of a common film of a sheet-like conductive carbon material and a porous fiber substrate;

Fig. 3 is the step diagram of the manufacturing method of the antenna of the radio frequency identification tag of the present invention;

FIG. 4 is a schematic structural diagram of the antenna of the radio frequency identification tag of the present invention;

FIG. 5 is a graph of signal gain of the radio frequency identification tag antenna of the present invention at different frequencies.

Symbol Description

10 porous fiber substrate 20 conductive layer

21 flake conductive carbon material

Detailed ways

The positional relationships described in the following embodiments include: up, down, left and right. Unless otherwise specified, they are all based on the directions in which the components are drawn in the drawings.

An embodiment of the conductive ink composition used to make the antenna of the radio frequency identification tag in the present invention comprises: a sheet-like conductive carbon material containing a graphite structure, a conductive filler, a dispersant and a solvent, and the solid content of the conductive ink composition The weight ratio of the conductive ink is 2-85% (wt%). Wherein the flaky conductive carbon material accounts for 10 to 90% (wt%) of the total solid weight, generally in the form of powder, and the flaky conductive carbon material includes graphene, graphite micro flakes, natural graphite, and flaky carbon black (such as KS6); the conductive filler accounts for 10-90% (wt%) of the total solid weight, and the conductive filler includes any of other shapes of conductive carbon materials, conductive metal particles, conductive oxides, and conductive polymers Or a combination of more than one; other shapes of conductive carbon materials include graphene, graphite, carbon nanotubes, nanocarbon spheres, conductive carbon black any one or a combination of more than one; conductive metal particles include platinum, gold, Palladium, ruthenium, silver, copper, nickel, zinc, any one or a combination of more than one or an alloy; conductive oxides containing any one or a combination of palladium oxide or ruthenium oxide; conductive polymers Contains any one or a combination of polythiophenes, polypyrroles, polyacetylenes, and polyaniline derivatives. The dispersant accounts for 0.0001 to 10% by weight of the total solids (wt%). The dispersant can be an ionic dispersant or a nonionic dispersant. The ionic dispersant includes P-123, Tween20, Xanthan gum, Carboxymethyl Cellulose (CMC), Triton X-100, Polyvinylpyrrolidone (PVP), any one or combination of more than one of Brji 30, wherein the nonionic dispersant contains Poly(sodium 4-tyrenesulfonate) (PSS), 3- [(3-Cholamidopropyl)dimethyl ammonio]-1-propanesufonate (CHAPS), Hexadecyltrimethylammonium bromide (HTAB), Sodium taurodeoxycholate hydrate (SDS), 1-Pyrenebutyric acid (PBA) any one or a combination of more than one.

The solvent can be pure water or an organic solvent, the organic solvent includes: N-Methyl-2-pyrrolidone (NMP), IPA (Isopropyl alcohol), ethanol, glycerol, ethylene glycol, butanol, propanol, Propylene glycol monomethyl ether (PGME ), any of Propylene glycol monomethylether acetate (PGMEA).

Please refer to Fig. 1 and Fig. 2, the antenna structure of radio frequency identification tag of the present invention comprises: a porous fibrous base material 10 and a conductive layer 20, and the composition of conductive layer 20 comprises: sheet-like conductive carbon material containing graphite structure, Other conductive fillers and dispersants, wherein the flaky conductive carbon material accounts for 10-90% (wt%) of the total solid weight, and other conductive fillers account for 10-90% (wt%) of the total solid weight, the aforementioned The weight ratio of the dispersant to the total solid is 0.0001-10% (wt%).

Please refer to FIG. 3 for the manufacturing method steps of the antenna structure of the radio frequency identification tag of the present invention, including:

1. Prepare a porous fibrous substrate 10. The porous fibrous substrate 10 includes any one of general paper, hemp paper and polyethylene terephthalate (abbreviated as polyester, Polyethylene Terephthalate, PET). kind;

2. Prepare a conductive ink composition without a polymer binder, especially a conductive ink composition without a polymer binder. The conductive ink composition includes: a sheet-like conductive carbon material containing a graphite structure, a conductive Filler, dispersant and solvent, wherein the sheet-like conductive carbon material accounts for 10-90% (wt%) of the total solid weight, the conductive filler accounts for 10-90% (wt%) of the total solid weight, and the dispersant accounts for 10-90% (wt%) of the total solid weight. The weight ratio of the total solids is 0.0001% to 10% (wt%), and the weight ratio of the solid content of the aforementioned conductive ink composition is 2% to 85% (wt%);

3. The conductive ink composition is coated on the surface of the porous fibrous substrate 10 according to the shape of the antenna. The coating implementation can be done by printing (including any one of screen printing, letterpress printing and gravure printing) and spraying. Ink printing (inkjet printing) any one of the ways; and

4. Evaporate the solvent of the conductive ink composition by thermal drying to form a conductive layer 20 on the surface of the porous fiber substrate 10, and part of the conductive layer 20 penetrates into the pores between the fibers of the porous fiber substrate 10 and adheres to the Porous fibrous substrate 10.

5. After the drying and curing step, roll the conductive layer 20 attached to the surface of the porous fibrous substrate 10 to a thickness reduction ratio of the original total thickness of the porous fibrous substrate 10 and the printed antenna. 50-90% ratio.

For the conductive paste containing a polymer resin binder, after curing, the conductive filler can be firmly grasped due to the shrinkage of the resin binder during curing to obtain a conductive layer with good adhesion. Table 2 below compares the commercial epoxy resin conductive silver paste with the graphene/metal composite conductive paste without polymer resin adhesive in this case. In the conductive layer obtained from the commercial epoxy resin conductive silver paste, the polymer has been adhered During the rolling process of the conductive filler firmly grasped by the agent, the conductive filler will loosen from the original firmly adhered resin due to the force of extrusion, and the adhesive will also spread on the surface due to extrusion. The conductive filler blocks the original conductive path, which increases the resistance at both ends of the printed antenna (from 2.1 ohms to 2.5 ohms, and the resistance increases by 19% after rolling); in addition, excessive rolling pressure will also cause polymer The phenomenon that the resin sticks back to the roller may cause part of the printed antenna to peel off from the substrate and stick to the roller; therefore, the conductive paste containing polymer adhesives generally does not reappear after printing and curing. After rolling this process. On the contrary, the conductive ink composition of the present invention is basically prepared as a conductive paste, especially a conductive paste without a polymer adhesive, and the conductive fillers can be more tightly contacted by rolling. , and there is no non-conductive polymer adhesive in the middle, the terminal resistance of the printed antenna can be further reduced significantly (1.8 ohms become 0.9 ohms, and the resistance drops by 50% after rolling), and the sheet carbon material after rolling The structure can stabilize the adhesion of the entire conductive layer; in addition, there is no problem of excessive pressure and anti-sticking of the wheel.

Table 2. Resistance before and after rolling of commercial conductive silver paste containing polymer adhesive and conductive paste without polymer adhesive in this case.

It can be understood from the above description that the antenna structure of the radio frequency identification tag of the present invention is to apply the above-mentioned conductive ink composition on the surface of the porous fiber substrate 10 by printing or ink-jet printing according to the shape of the antenna, and part of the conductive ink composition The ink composition penetrates between the fibers of the porous fibrous substrate 10. Since the sheet-like conductive carbon material 21 contained in the conductive ink has good film-forming properties, the sheet-like conductive carbon material 21 can be used with Porous fiber base material 10 co-membrane reaches the effect of adhesion (seeing Fig. 2), constitutes the antenna structure of a kind of radio frequency identification tag not containing metal and adhesive by porous fiber base material 10 and conductive layer; The ink composition does not contain an insulating adhesive, so the conductivity of the antenna structure can be improved, resistance and production cost can be reduced.

In an embodiment of the above-mentioned method steps of the present invention, if the conductive ink composition is coated on the surface of the porous fiber substrate 10 by screen printing, wherein the mesh number of the screen is between 100 and 400 mesh, the printing The accuracy can reach 100 μm; if inkjet printing is used to coat the conductive ink composition on the surface of the porous fiber substrate 10, according to the positioning ability of the inkjet printing device, the best printing accuracy can even reach 0.1um level. Please refer to FIG. 4 for a schematic diagram of the antenna structure of the radio frequency identification tag printed by the conductive ink composition of the present invention, wherein the appearance of the conductive layer 20 printed by the conductive ink composition of the present invention is the same as that of the traditional aluminum foil etching method, and it is conductive The connection point between the layer 20 and the IC chip can be accurate within 10um without short circuit (see the partial enlarged structure in FIG. 4 ). In another embodiment of the present invention, the conductive ink composition can be directly printed on paper to directly prepare tear-off RFID tags, which can greatly simplify the complex process of traditional metal etching and transfer.

In one embodiment of the present invention, the porous fibrous substrate 10 can be selected from a material with high fiber density and many capillary pores. If it is paper, the basis weight range of the selected paper is 30-200g/m2, and the density is 0.5-2.5 g/cm3, the average pore size is 0.02-500μm.

After the conductive layer 20 is printed, the solvent in the conductive ink is evaporated in a drying step. One embodiment of the drying method is a thermal drying method. The heating temperature ranges from 50 to 300°C. The higher the temperature, the shorter the heating time. In one embodiment of the method of the present invention, a rolling step is included. After the drying step, the conductive layer 20 attached to the surface of the porous fibrous substrate 10 is rolled and the compression ratio is 50-90% of the original thickness by rolling. , the density and conductivity of the conductive layer 20 can be further improved. For the purpose of reducing the resistance, it can be achieved by coating a thicker conductive layer 20 and increasing the density of the conductive layer 20. Therefore, the thicker the thickness and the larger the particle size, the sheet-shaped conductive carbon material can be selected, which is suitable for radio frequency identification. The resistance of the sheet-shaped conductive carbon material of the label is 0.1-50 ohm/sq (resistivity 1×10-6-2.5×10-4 ohm-m).

Please refer to FIG. 5 which is a signal gain diagram of the antenna structure of the radio frequency identification tag of the present invention at different frequencies, showing that different antenna patterns are printed on the surface of the porous fiber substrate 10 using the conductive ink composition without polymer adhesive of the radio frequency identification tag of the present invention. , the signal gain (gain) situation obtained at each frequency. From the comparison of the data in Fig. 5, it can be seen that through different antenna designs, specific signals can be arranged in different frequency ranges for the use of radio frequency identification tags of specific frequencies, and the conductive ink composition of the radio frequency identification tag of the present invention is used in the porosity The antenna structure printed on the surface of the fiber substrate 10 has quite obvious signals in the UHF and microwave frequency ranges.

The antenna structure of the invention radio frequency identification tag is electrically connected to the IC chip, and the reader reading test is performed. The antenna pattern of the tested antenna structure is a commonly used UHF design: one is a relatively simple linear antenna, and the other is a more complex antenna with many bends. The sheet resistance and reading test results of the two antenna structures are shown in Table 3. It is confirmed that the antenna structure printed on the surface of the porous fiber substrate 10 using the conductive ink composition of the radio frequency identification tag of the present invention without a polymer adhesive is suitable for high frequency (HF, 13.56 MHz), ultra high frequency ( UHF, 868 to 956MHz) and microwave (Microwave, 2.45GHz) radio frequency identification tags.

Table 3 The antenna structure of the radio frequency identification tag is electrically connected to the reading test table of the IC chip

The embodiments and/or implementations described above are only used to illustrate the preferred embodiments and/or implementations of the technology of the present invention, and are not intended to limit the implementation of the technology of the present invention in any form. Personnel, without departing from the scope of the technical means disclosed in the content of the present invention, may make some changes or modifications to other equivalent embodiments, but they should still be regarded as essentially the same technology or embodiment as the present invention.

Claims (15)

1. A conductive ink composition for making an antenna of a radio frequency identification tag, comprising: a sheet-like conductive carbon material containing a graphite structure, a conductive filler, a dispersant and a solvent. 2. the conductive ink composition that is used to make the antenna of radio frequency identification label as claimed in claim 1, it is characterized in that, this sheet-like conductive carbon material comprises any one of graphene, natural graphite microflake, sheet-like carbon black or a combination of more than one. 3. the conductive ink composition that is used to make the antenna of radio frequency identification label as claimed in claim 1, is characterized in that, this conductive filler comprises the conductive carbon material of other shapes, conductive metal particle, conductive oxide, conductive polymer wherein any one or a combination of more than one. 4. the conductive ink composition that is used to make the antenna of radio frequency identification label as claimed in claim 3, is characterized in that, this conductive carbon material comprises graphene, graphite, carbon nanotube, nanocarbon sphere, conductive carbon black wherein any One or a combination of more than one. 5. the conductive ink composition that is used to make the antenna of radio frequency identification label as claimed in claim 3, is characterized in that, this conductive metal particle comprises any one of platinum, gold, palladium, ruthenium, silver, copper, nickel, zinc A combination or alloy of one or more. 6 . The conductive ink composition for making an antenna of a radio frequency identification tag according to claim 3 , wherein the conductive oxide comprises any one or a combination of palladium oxide or ruthenium oxide. 7. The conductive ink composition for making the antenna of radio frequency identification tag as claimed in claim 3, is characterized in that, this conductive macromolecule comprises polythiophenes, polypyrroles, polyacetylenes, polyaniline derivatives wherein Any one or a combination of more than one. 8. A method for manufacturing an antenna of a radio frequency identification tag, comprising: (1) preparing a porous fiber substrate; (2) preparing a conductive ink composition, the conductive ink composition comprising: graphite-containing Sheet-shaped conductive carbon material, conductive filler, dispersant and solvent; (3) printing the conductive ink composition on the porous fiber substrate; (4) printing the conductive ink composition on the porous fiber substrate The ink composition is dried and cured to form a printed antenna; (5) rolling the cured printed antenna. 9. The manufacturing method of the antenna of the radio frequency identification tag as claimed in claim 8, it is characterized in that, comprising a rolling step, after the drying and curing step, the printing attached to the surface of the porous fiber substrate is adhered to by rolling The thickness compression ratio of the antenna is 50-90% of the original total thickness of the porous fiber substrate and the printed antenna. 10. The manufacture method of the antenna of radio frequency identification tag as claimed in claim 8, is characterized in that, this sheet-like conductive carbon material comprises any one or more wherein of graphene, natural graphite microflake, sheet-like carbon black combination. 11. The method for manufacturing the antenna of the radio frequency identification tag as claimed in claim 8, wherein the conductive filler comprises any one of conductive carbon materials, conductive metal particles, conductive oxides, and conductive polymers of other shapes or more than one combination. 12. The manufacturing method of the antenna of radio frequency identification tag as claimed in claim 11, is characterized in that, this conductive carbon material comprises graphene, graphite, carbon nanotube, nanocarbon sphere, conductive carbon black wherein any one or a kind combination of the above. 13. The method for manufacturing the antenna of the radio frequency identification tag as claimed in claim 11, wherein the conductive metal particles comprise any one or more of platinum, gold, palladium, ruthenium, silver, copper, nickel, zinc combinations or alloys. 14. The manufacturing method of the radio frequency identification tag antenna according to claim 11, wherein the conductive oxide comprises any one or a combination of palladium oxide or ruthenium oxide. 15. The method for manufacturing the antenna of the radio frequency identification tag as claimed in claim 11, wherein the conductive polymer comprises any one or one of polythiophenes, polypyrroles, polyacetylenes, and polyaniline derivatives more than one combination.