Abstract:
A radio frequency identification (RFID) antenna coil and fabricated method therefor are provided. One or more antennas are connected to be a plane or three-dimensional structure via substrate surface modified procedure, an inkjet-printing process for forming antenna patterning, and an electroless plating process, so that the RFID antenna coil can be flexibility and have higher inductance.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This non-provisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No(s). 094143233 filed in Taiwan, R.O.C. on Dec. 7, 2005, the entire contents of which are hereby incorporated by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of Invention  
         [0003]     The present invention relates to an antenna coil structure and fabricated method therefor and more particularly, to a radio frequency identification (RFID) antenna coil with flexible substrate, higher inductance and a fabricated method therefor.  
         [0004]     2. Related Art  
         [0005]     Nowadays, non-contact radio frequency systems have been generally applied in many industries. In the future, after each product leaves the factory, a non-contact radio frequency system will be attached on the product. This system will record relative data about upstream and downstream manufacturers of the product (such as product specification, material, and shipping data), data required by logistics (such as logistics network and stock information), information required by consumers (such as price, qualified mark, instruction manual, and service station). And different clients have different access rights to the information.  
         [0006]     The structure of the radio frequency identification (RFID) antenna coil system may be divided into two parts: the first part is a card module, comprising: a power supply and an antenna coil for transmitting and receiving data, a transceiver module, and an identification data; the second part is a reader device, comprising: a transceiver antenna coil, a transceiver module, and a control circuit. The reader device transmits an electromagnetic wave, and when the card module approaches the reader device, the antenna coil in the card module will receive the electromagnetic wave, and store the energy as an electric power for the card module, and transmit the identification date in the card module to the reader device as a radio wave, for confirmation and further control.  
         [0007]     To enhance the inductive coupling efficiency, usually the number of turns of coil windings is increased to enhance inductance. However, many problems may be caused with the fabricated method, such as, enlarged element volume, increased resistance value, multi-circle signal noise, reduced induction distance, and weaker recognition rate.  
         [0008]     Referring to Japanese Patent No. JP2002368525, wherein the antenna coil is processed with a multi-layer lamination and a magnetic powder substrate (e.g. Mg, Fe, Co etc.) perpendicular to the antenna coil is disposed at a central part of the antenna coil, thereby increasing the inductance, such a method can increase the inductance, however, the element thickness is increased, and also the antenna is inflexible, and therefore, the method has no essential advantage and competitiveness in market application.  
         [0009]     Referring to Japanese Patent No. JP2000261230, the fabrication of an antenna coil is similar to the above one in that multi-layers of antenna are laminated, and the difference there-between is in that here the magnetic substance is arranged in a same direction with the metal wiring. The element thickness can be reduced; however, the inductance can thus only be raised in a limited range.  
         [0010]     Therefore, it becomes one of the problems to be solved by the researchers how to provide a RFID antenna coil and fabricated method therefor, for enabling the antenna coil to be flexibility and have higher inductance.  
       SUMMARY OF THE INVENTION  
       [0011]     In view of above problems, an object of the present invention is to provide a radio frequency identification (RFID) antenna coil and fabricated method therefor, for raising the inductance of the antenna through the resonance between the magnetic metal layer and the metal wiring.  
         [0012]     Therefore, to achieve the above object, the fabricated method of the RFID antenna coil disclosed in the present invention comprises: processing a substrate by a surface modified procedure (e.g. plasma treatment, ion treatment, or ozone treatment), to form a self-assembly membranes (SAMs) on a surface of the substrate; spray catalyst on the SAMs of the substrate according to patterning; carrying out the first electroless plating procedure for the substrate, to generate a magnetic metal layer corresponding to the wiring pattern on the catalyst; and carrying out the second electroless plating procedure for the substrate, to generate the metal layer on the magnetic metal layer.  
         [0013]     Furthermore, to achieve above object, the fabricated method of a RFID antenna coil disclosed in the present invention comprises: processing a substrate through a surface modified procedure, to form the SAMs on the top and bottom surfaces of the substrate; forming a cover layer on the SAMs; fabricating at least one through hole in the substrate; further forming the SAMs on the cover layer; spray catalyst on the SAMs of the cover layer according to patterning; carrying out the first electroless plating procedure for the substrate, to generate a magnetic metal layer corresponding to the patterning on the catalyst; and carrying out the second electroless plating procedure for the substrate, to generate a metal layer on the magnetic metal layer.  
         [0014]     Furthermore, to achieve the above object, the fabricated method of the RFID antenna coil disclosed in the present invention comprises: processing a substrate by surface modified procedure, to form the SAMs on the top and bottom surfaces of the substrate; spray catalyst on the SAMs of the top and bottom surfaces of the substrate according to the first patterning; electroless plating the substrate, to generate a magnetic metal corresponding to the first patterning on the top and bottom surfaces of the substrate; forming an insulation layer on the magnetic metal wiring; fabricating at least one through hole in the substrate; further forming the SAMs on the insulation layer; spray the catalyst on the insulation layer of the top surface of the substrate according to the second patterning; carrying out a first chemical plating procedure for the substrate, to generate a metal wiring corresponding to the second patterning on the catalyst of the top surface of the substrate; spray the catalyst on the insulation layer of the bottom surface of the substrate according to a third patterning; and carrying out a second chemical plating procedure for the substrate, to generate a metal layer corresponding to the third patterning on the catalyst of the bottom surface of the substrate.  
         [0015]     Furthermore, to achieve the above object, a RFID antenna coil structure disclosed in the present invention comprises: a substrate; a SAMs, formed on a surface of the substrate; a magnetic metal layer, formed on the SAMs; and a metal layer, formed on the magnetic metal layer.  
         [0016]     With the RFID antenna coil structure and fabricated method therefor, the antenna coil is made flexible by a flexible substrate, and the thickness of the antenna coil can be reduced and its inductance can be raised by generating a magnetic metal layer and a metal by electroless plating.  
         [0017]     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]     The present invention will become more fully understood from the detailed description given herein below for illustration only, and which thus is not limitative of the present invention, and wherein:  
         [0019]      FIG. 1  is a flow chart of fabricating a single-layer radio frequency identification (RFID) antenna coil according to a first embodiment of the present invention;  
         [0020]      FIG. 2  is a flow chart of fabricating a self-assembly membranes (SAMs) according to the present invention;  
         [0021]      FIG. 3  is a schematic view of the single-layer RFID antenna coil according to the first embodiment of the present invention;  
         [0022]      FIG. 4  is a flow chart of fabricating a double-layer RFID antenna coil according to a second embodiment of the present invention;  
         [0023]      FIG. 5A  is a schematic view of the double-layer RFID antenna coil according to the second embodiment of the present invention;  
         [0024]      FIG. 5B  is a schematic view of a multi-layer RFID antenna coil according to the second embodiment of the present invention;  
         [0025]      FIGS. 6A and 6B  are flow charts of fabricating a thread typed RFID antenna coil according to a third embodiment of the present invention; and  
         [0026]      FIG. 7  is a schematic view of a thread typed RFID antenna coil according to the third embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0027]     Referring to  FIG. 1 , it is a flow chart of fabricating a single-layer radio frequency identification (RFID) antenna coil according to a first embodiment of the present invention, which comprises the following steps. Process a substrate through a surface modified procedure (e.g. plasma treatment, ion treatment, or ozone treatment), to form a self-assembly membranes (SAMs) on a surface of the substrate (e.g. a top surface or a bottom surface) (Step  100 ). Spray catalyst (such as Na 2 PdCl 4  solutions and Pd (NH 3 ) 4 Cl 2  solutions) on the SAMs of the substrate according to patterning by a PZT inkjet printer (Step  101 ), wherein the PZT inkjet printer sprays the catalyst on the substrate.  
         [0028]     Carry out the first electroless plating procedure for the substrate, to generate a magnetic metal (such as Ni, Fe, or Co) layer corresponding to the patterning on the catalyst (Step  102 ). In the first electroless plating procedure, the substrate is immersed in an electroless plating tank filled with electroless plating bath (such as Ni plating solution), and then a magnetic metal layer is generated based on a redox potential principle, wherein the thickness of the magnetic metal layer can be changed by adjusting the electroless plating bath temperature and the electroless plating time. Then, take out the impurities on the substrate for carrying out a rinsing procedure (Step  103 ).  
         [0029]     Carry out a second electroless plating procedure for the substrate, to generate a metal (such as Al, Ag, Cu, Ni, Fe, Co, Cd, or Pt) layer on the magnetic metal layer (Step  104 ). In the second electroless plating procedure, the substrate is immersed in an electroless plating tank filled with electroless plating bath (e.g. Cu plating solution), and then a metal layer is generated based on the redox potential principle, wherein the thickness of the metal layer can be changed by adjusting the electroless plating bath temperature and electroless plating time.  
         [0030]     Referring to  FIG. 2 , it is a flow chart of fabricating SAMs according to the present invention, which comprises the following steps. At first, immerse a substrate in an anionic polyelectrolytes solution (e.g. PAA solution) for several minutes (Step  200 ). Then, take out and soak the substrate in DI water (Step  201 ). Then, soak the substrate in the cationic polyelectrolytes solution (e.g. PAA solution) for several minutes (Step  202 ). Take out the substrate and immerse it in DI water (Step  203 ). And then, back to Step  200 , repeat the above steps until the layers of required number are formed.  
         [0031]     Referring to  FIG. 3 , it is a schematic view of the single-layer antenna coil according to the first embodiment of the present invention, which comprises a substrate  10 , SAMs  11 , a catalyst  12 , a magnetic metal layer  13 , and a metal layer  14 .  
         [0032]     In practice, the substrate  10  may comprise a glass substrate, a PET substrate, a flame retardant fiber glass epoxy (FR- 4 ) substrate, and a flexible substrate (e.g. Polyimide substrate).  
         [0033]     The SAMs  11  is formed on a surface of the substrate  10 , and is in a structure of multi-layer membrane, for increasing the metal adhesiveness during the electroless plating processing of the substrate  10  and the lubricity and anti-corrosiveness of the substrate itself. In practice, the SAMs  11  may adopt a PAH/PAA multi-layer membranes.  
         [0034]     The catalyst  12  is formed on the SAMs  11 , and in practice may comprise Na 2 PdCl 4  solutions and Pd (NH 3 ) 4 Cl 2  solutions.  
         [0035]     The magnetic metal layer  13  is formed on the catalyst  12  and in practice may comprise Ni, Fe, and Co material.  
         [0036]     The metal layer  14  is formed on the magnetic metal layer  13 , and in practice may comprise Al, Ag, Cu, Ni, Fe, Co, Cd, and Pt material.  
         [0037]     Referring to  FIG. 4 , it is a flow chart of fabricating a double-layer RFID antenna coil according to a second embodiment of the present invention, which comprises the following steps. At first, process a substrate by a surface modified procedure (e.g. plasma treatment, ion treatment, or ozone treatment), to form SAMs on the top and bottom surfaces of the substrate (Step  300 ), wherein the step of forming the SAMs is as shown in  FIG. 2 , and will not be described here.  
         [0038]     Then, form a cover layer on the SAMs (Step  301 ). Fabricate at least one through hole in the substrate by mechanical drilling or laser drilling (Step  302 ). Further form SAMs on the cover layer (Step  303 ). Spray catalyst (such as Na 2 PdCl 4  solution and Pd (NH 3 ) 4 Cl 2  solution) on SAMs of the cover layer according to patterning by a PZT inkjet printer (Step  304 ), wherein the PZT inkjet printer sprays the catalyst.  
         [0039]     Carry out the first electroless plating procedure for the substrate, to generate a magnetic metal (e.g. Ni, Fe or Co) layer corresponding to the patterning on the catalyst (Step  305 ). In the first electroless plating procedure, the substrate is immersed in an electroless plating tank filled with electroless plating bath (e.g. Ni plating solution), and then a magnetic metal layer is generated based on the redox potential principle, wherein the thickness of the magnetic metal layer may be changed by adjusting the electroless plating bath temperature and electroless plating time. Remove the cover layer on the substrate (Step  306 ). Then, take out the substrate to carry out a rinsing procedure (Step  307 ).  
         [0040]     Carry out a second electroless plating procedure for the substrate, to generate a metal (such as Al, Ag, Cu, Ni, Fe, Co, Cd, or Pt) layer on the magnetic metal layer (Step  308 ). In the second electroless plating procedure, the substrate is immersed in an electroless plating tank filled with electroless plating bath (e.g. Cu plating solution), and a metal layer is generated based on the redox potential principle, wherein the thickness of the metal layer can be changed by adjusting the electroless plating bath temperature and electroless plating time.  
         [0041]     Referring to  FIG. 5A , it is a schematic view of the double-layer RFID antenna coil according to the second embodiment of the present invention. Part of the structure is as shown in  FIG. 3  and will not be described. SAMs  11 , a magnetic metal layer  13 , and a metal layer  14  are formed on the top and bottom surfaces of the substrate  10  respectively. And a through hole  20  is formed in the substrate  10  for connecting other embodied passive components (not shown).  
         [0042]     Referring to  FIG. 5B , it is a schematic view of a multi-layered RFID antenna coil according to the second embodiment of the present invention. Part of the structure is as shown in  FIG. 5A , and will not be described here. Another substrate with metal wiring is pressed onto the top surface or the bottom surface of the substrate  10 , and a through hole  20  is formed in each substrate for connecting other embodied passive components (not shown).  
         [0043]     Referring to  FIGS. 6A and 6B , they are flow charts of fabricating a thread typed antenna coil according to a third embodiment of the present invention, which comprise the following steps. At first, process a substrate by a surface modified procedure (e.g. plasma treatment, ion treatment, or ozone treatment), to form SAMs on the top and bottom surfaces on the substrate (Step  400 ), wherein the step of forming the SAMs is as shown in  FIG. 2 , and will not be described here.  
         [0044]     Spray catalyst (such as Na 2 PdCl 4  solution and Pd (NH 3 ) 4 Cl 2  solution) on the SAMs of the top and bottom surfaces of the substrate according to a first patterning by a PZT inkjet printer (Step  401 ), wherein the PZT inkjet printer sprays the catalyst on the substrate.  
         [0045]     Carry out a first electroless plating procedure for the substrate, to generate a magnetic metal (e.g. Ni, Fe, or Co) layer corresponding to the first patterning (Step  402 ). In the first electroless plating processing, the substrate is immersed in an electroless plating tank filled with electroless plating bath (e.g. Ni plating solution), and a magnetic metal layer is generated based on the redox potential principle, wherein the thickness of the magnetic metal layer can be changed by adjusting the electroless plating bath temperature and electroless plating time. Form an insulation layer on the magnetic metal layer (Step  403 ).  
         [0046]     Fabricate at least one through hole in the substrate through mechanical drilling or laser drilling (Step  404 ). Form SAMs on the insulation layer (Step  405 ). Spray the catalyst on the insulation layer of the top surface of the substrate according to a second patterning by a PZT inkjet printer (Step  406 ).  
         [0047]     Carry out a second electroless plating procedure to the substrate, to generate a metal (such as Al, Ag, Cu, Ni, Fe, Co, Cd, or Pt) layer corresponding to the second patterning on the catalyst of the insulation layer of the top surface of the substrate (Step  407 ). In the second electroless plating procedure, the substrate is immersed in an electroless plating tank filled with electroless plating bath (e.g. Cu plating solution), and a metal layer is generated based on a redox potential principle, wherein the thickness of the metal layer can be changed by adjusting the electroless plating bath temperature and electroless plating time. Then, take out the substrate to carry out a rinsing procedure (Step  408 ).  
         [0048]     Spray the catalyst on the insulation layer of the bottom surface of the substrate according to a third patterning by a PZT inkjet printer (Step  409 ). Carry out a third electroless plating procedure for the substrate, to generate a metal (such as Al, Ag, Cu, Ni, Fe, Co, Cd, or Pt) layer corresponding to the third patterning on the catalyst of the insulation layer of the bottom surface of the substrate (Step  410 ). In the third electroless plating procedure, the substrate is immersed in an electroless plating tank filled with an electroless plating bath (e.g. Cu plating solution), and a metal layer is generated based on the redox potential principle, wherein the thickness of the metal layer can be changed by adjusting the electroless plating bath temperature and electroless plating time. In the embodiment, the second patterning and the third patterning form a thread shape.  
         [0049]     Referring to  FIG. 7 , it is a schematic view of the thread typed RFID antenna coil according to the third embodiment of the present invention. Part of the structure is as shown in  FIG. 3 , and will not be described here. SAMs  11 , a magnetic metal layer  13 , an insulation layer  15  and a metal layer  14  are formed on the top and bottom surfaces of the substrate  10  respectively, wherein the metal layer  14  is selectively formed on the top surface or the bottom surface of the substrate  10 . A through hole  20  is formed in the substrate  10  for connecting other embodied passive components (not shown).  
         [0050]     With the RFID antenna coil and fabricated method therefor, the antenna coil is made flexible by a flexible substrate, and the antenna coil thickness can be reduced and the antenna inductance can be raised through generating a magnetic metal layer and a metal layer by electroless plating.  
         [0051]     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.