Patent Publication Number: US-7916032-B2

Title: Radio frequency identification (RFID) tag and manufacturing method thereof

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation Application of U.S. patent application Ser. No. 11/006,731, filed on Dec. 8, 2004, now U.S. Pat. No. 7,342,498, the disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1) Field of the Invention 
     The present invention relates to a radio frequency identification (RFID) tag such as a non-contact integrated circuit (IC) card, which receives power supply and information from, and transmits information to, an external device. The “RFID tag” used in the present invention is also known to one skilled in the art as an “RFID tag inlay”, inlay being an internal constituent part (inlay) used in the “RFID tag”. The “RFID tag” is also known as a “wireless IC tag”. 
     2) Description of the Related Art 
     RFID tags such as a non-contact integrated circuit that receive using radio waves, power supply and information from an external device such as an IC card reader/writer and then transmit the received information to the external device contact-free are being used in recent years. A typical RFID tag includes an antenna pattern and an integrated circuit (IC) chip. The antenna pattern, which transmits and receives data, is mounted on a substrate made of plastic, paper, and the like. The antenna pattern and a capacity element built into the IC chip form a resonance circuit, and the RFID tag communicates via radio waves with the external device by means of the antenna pattern. 
     However, there may be instances where an RFID tag is used close to a wave-absorbing material such as a wine bottle or a human body. The wave-absorbing material poses a problem in the communication process since it absorbs the radio waves (for instance, radio waves in the ultra high frequency (UHF) band) that are required by the RFID tag for transmission and reception.  FIG. 26  and  FIG. 27  are drawings of conventional well-known means that enhance the gain of an antenna.  FIG. 26  is a cross-sectional view of a conventional RFID tag in which a plane antenna is provided on the wave-absorbing material.  FIG. 27  is a cross-sectional view of a conventional RFID tag in which a loop antenna is provided on the wave-absorbing material. 
     As shown in  FIG. 26 , a substrate  110  having a plane antenna  120  is fixed to a wave-absorbing material  100  by means of an adhesive  140 . The plane antenna  120  is connected by means of a feeding point  130  to an IC chip (not shown) mounted on another substrate. 
     As a related conventional technology, the RFID tag with a plane coil antenna is well known (for instance, see Japanese Patent Laid-Open Publication No. 2004-206479). An RFID tag with a plane coil antenna includes a dielectric antenna substrate and an antenna coil. The antenna coil includes a first set of coils located on one surface of the antenna substrate and a second set of coils located on a second surface of the antenna substrate. The first set of coils and the second set of coils straddle the antenna substrate, each coil of the first set and each coil of the second set alternating with each other such that a portion of the two coils face each other. The first set of coils and the second set of coils are connected in a predetermined sequence. 
     As shown in  FIG. 27 , a loop antenna  160 , which is in a sheet of a metal, is fixed on the wave-absorbing material  100  by means of the adhesive  140 . The loop antenna  160  encloses a hollow interior  150  and is connected by means of the feeding point  130  to an IC chip (not shown) mounted on another substrate. The RFID loop antenna is widely used in pagers. 
     However, in a RFID tag with the plane antenna  110  shown in  FIG. 26 , an antenna pattern that has a small area can be employed. If the area of the antenna pattern is small, the communication distance is short. The wave-absorbing material  100  causes further degradation of antenna response because it absorbs the radio waves. 
     Similarly, the antenna response is affected and the communication distance also decreases significantly in the case of the RFID tag fabricated using a plane coil antenna disclosed in Japanese Patent Laid-Open Publication No. 2004-206479, since the wave-absorbing material  100  absorbs the radio waves. 
     However, in an RFID tag with a loop antenna  160  shown in  FIG. 27 , since the loop antenna  160  has a diameter, the antenna cannot be made slim. Therefore, the loop antenna can not be employed in small RFID tags. 
     Moreover, the loop antenna  160  may get crushed when subjected to external pressure since it has a hollow interior  150 . 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to solve at least the problems in the conventional technology. 
     An RFID tag according to an aspect of the present invention includes a dielectric member; an antenna pattern formed on and around a surface of the dielectric member whereby the antenna pattern forms a loop; and an IC chip with a built-in communication circuit and a built-in memory circuit, the IC chip being electrically connected to the antenna pattern. 
     An RFID tag according to another aspect of the present invention includes a dielectric member; a film substrate that includes an antenna pattern, the film substrate being tied on and around the dielectric member whereby the antenna pattern forms a loop; and an IC chip with a built-in communication circuit and a built-in memory circuit, the IC chip being electrically connected to the antenna pattern. 
     An RFID tag according to still another aspect of the present invention includes a dielectric member; a dielectric member support that slidably supports the dielectric member; a film substrate that includes an antenna pattern, the film substrate being tied on and around the dielectric member whereby the antenna pattern forms a loop; and an IC chip with a built-in communication circuit and a built-in memory circuit, the IC chip being electrically connected to the antenna pattern. 
     An RFID tag manufacturing method according to still another aspect of the present invention includes mounting a film substrate having a transceiving antenna pattern on a surface of a dielectric member and forming a loop antenna; and electrically connecting an IC chip to the antenna pattern, the IC chip including at least a built-in communication circuit and a built-in memory circuit. 
     An RFID tag manufacturing method according to still another aspect of the present invention includes forming a loop antenna on a surface of a dielectric member by means of a transceiving antenna pattern; and electrically connecting an IC chip to the antenna pattern, the IC chip including a built-in communication circuit and a built-in memory circuit. 
     An RFID tag manufacturing method according to still another aspect of the present invention includes electrically connecting an IC chip to a first transceiving antenna pattern of a first film substrate, wherein the IC chip includes a built-in communication circuit and a built-in memory circuit; laminating a first surface of a dielectric member with the first film substrate such that the IC chip mounted on the first film substrate fits into a concavity provided on the dielectric member; laminating a second surface of the dielectric member with a second film substrate having a second transceiving antenna pattern; and electrically connecting the first transceiving antenna pattern of the first film substrate and the second transceiving antenna pattern of the second film substrate by means of a conductive member. 
     The other objects, features, and advantages of the present invention are specifically set forth in or will become apparent from the following detailed description of the invention when read in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a RFID tag according to a first embodiment of the present invention; 
         FIG. 2  is a cross-sectional view of the RFID tag mounted on a wave-absorbing material; 
         FIG. 3  is a schematic diagram that illustrates a principle of a formation of a large current loop; 
         FIG. 4  is a perspective view of the RFID tag according to a second embodiment of the present invention; 
         FIG. 5  is a top view of a film substrate shown in  FIG. 4 ; 
         FIG. 6  is a perspective view of a modification of the RFID tag shown in  FIG. 4 ; 
         FIG. 7  is a perspective view of another modification of the RFID tag shown in  FIG. 4 ; 
         FIG. 8  is a perspective view of still another modification of the RFID tag shown in  FIG. 4 ; 
         FIG. 9  is a perspective view of the RFID tag according to a third embodiment of the present invention; 
         FIG. 10  is a top view of the film substrate shown in  FIG. 9 ; 
         FIG. 11  is a perspective view of the RFID tag according to a fourth embodiment of the present invention; 
         FIG. 12  is a top view of the film substrate shown in  FIG. 12 ; 
         FIG. 13  is a perspective view of the RFID tag according to a fifth embodiment of the present invention; 
         FIG. 14  is a perspective view of the RFID tag according to a sixth embodiment of the present invention; 
         FIG. 15  is a perspective view of the RFID tag in which an IC chip is mounted on chip pads formed on a dielectric member; 
         FIG. 16  is a perspective view of the RFID tag according to a seventh embodiment of the present invention; 
         FIG. 17  is a top view of the film substrate shown in  FIG. 16 ; 
         FIG. 18  is a perspective view of a modification of the RFID tag shown in  FIG. 16 ; 
         FIG. 19  is a cross-sectional view of the RFID tag according to an eighth embodiment of the present invention; 
         FIG. 20  is a perspective view of the RFID tag according to a ninth embodiment of the present invention; 
         FIG. 21  is a perspective view of the RFID tag in which the dielectric member is secured to a dielectric member support; 
         FIG. 22  is a perspective view of the RFID tag according to a tenth embodiment of the present invention; 
         FIG. 23  is a perspective view of the RFID tag according to an eleventh embodiment of the present invention; 
         FIG. 24  is a cross-sectional view of the RFID tag according to a twelfth embodiment of the present invention; 
         FIG. 25  is a cross-sectional view of the RFID tag to illustrate a lamination step; 
         FIG. 26  is a cross-sectional view of a conventional RFID tag with a plane antenna; and 
         FIG. 27  is a cross-sectional view of a conventional REID tag with a loop antenna. 
     
    
    
     DETAILED DESCRIPTION 
     Exemplary embodiments of a RFID tag and a manufacturing method thereof according to the present invention are explained next with reference to the accompanying drawings. The present invention is not limited to the present embodiment. 
       FIG. 1  is a perspective view of the RFID tag according to a first embodiment of the present invention.  FIG. 2  is a cross-sectional view of the RFID tag mounted on a wave-absorbing material.  FIG. 3  is a schematic diagram that illustrates a principle of the formation of a large current loop. As shown in  FIG. 1  and  FIG. 2 , a RFID tag  5  according to the first embodiment of the present invention includes a rectangular dielectric member  10 , an antenna pattern  30  that transmits and receives data, and an integrated circuit (IC) chip  40 . The antenna pattern  30  is a loop antenna tied around the surface of the dielectric member  10 . The IC chip  40  is electrically connected to the antenna pattern  30  via chip pads  32 . 
     The rectangular dielectric member  10  is composed of a dielectric material having a certain dielectric constant, and may be a high frequency substrate composed of resin containing glass, etc. The antenna pattern  30  on the plane surface of the dielectric member  10  is formed by etching a conductor (for instance, a metallic conductor such as copper). 
     A pair of chip pads  32  on which an IC chip  40  is mounted and that electrically connect the IC chip  40  to the antenna pattern  30  is also formed by etching along with the antenna pattern  30 . The antenna pattern  30  on the side surfaces (thickness of the dielectric member) of the dielectric member  10  is formed by a known side conduction method of plating. 
     The IC chip  40  includes a communication circuit that records and reads the information contact-free, a memory, and a designated control circuit. The IC chip  40  also includes chip electrodes that electrically connect the IC chip  40  to the chip pads  32  that extend to the antenna pattern  30 . The control circuit may not necessarily be provided within the IC chip  40 . 
     A manufacturing method of the RFID tag  5  is explained next. The antenna pattern  30  and the chip pads  32  are formed on the dielectric member  10  by etching process and the like to form a loop antenna (loop antenna formation step). 
     The IC chip  40  mounting step is carried out next. In other words, the IC chip  40  is mounted in such a way that the chip electrodes of the IC chip  40  are electrically connected to the chip pads  32 . A flip chip mount can be used as a mounting means. 
     As shown in  2 , the RFID tag  5  is secured on a wave-absorbing material  100  such as a wine bottle using the adhesive  140  (for instance, a two-sided tape) and is covered by a not shown specified protection film. The RFID tag  5  may be equipped beforehand with the protection film and the adhesive  140  in order to be secured to the article in which it is to be used. 
     The principle of the formation of a large current loop is explained next. The principle is the one by which the communication distance can be increased and is explained with reference to  FIG. 3 . The antenna pattern  30  forms a small loop antenna  30   a  around the dielectric member  10 . The small loop antenna  30   a  also forms an image current  30   b  on the wave-absorbing material  100 . 
     The small loop antenna  30   a  and the image current  30   b  form a large current loop  30   c . The formation of the large current loop  30   c  enhances the transmission gain and significantly increases the communication distance. In other words, reduction of communication distance can be controlled. Moreover, since the antenna pattern  30  is formed on the dielectric member  10 , the antenna pattern  30  does not get damaged even when it is subjected to external pressure. 
     The RFID tag  5  that has a structure as described above that can transmit accurate radio wave information due to enhanced transmission gain of the antenna when receiving power supply and information from and transmitting the received information to an external device (not shown) contact-free. As a result, the reliability of the data communication can be increased. Though a rectangular dielectric member  10  has been used in the RFID tag  5  according to the first embodiment, the dielectric member  10  may be of any shape (for instance, cylindrical, triangular prism, spherical, etc.) depending on the article it is intended for. 
       FIG. 4  is a perspective view of a RFID tag according to a second embodiment of the present invention.  FIG. 5  is a top view of a film substrate. The parts in the second embodiment that are identical to those in the first embodiment are assigned the same reference numerals and their description is made very brief or skipped altogether. 
     As shown in  FIG. 4 , the RFID tag  5  according to the second embodiment of the present invention includes the dielectric member  10 , a film substrate  20 , and the IC chip  40 . The film substrate  20  forms the antenna pattern  30  that transmits and receives data and is wrapped around the dielectric member  10 . The IC chip  40  is connected to the antenna pattern  30 . 
     The rectangular dielectric member  10  is composed of a dielectric material that has a designated dielectric constant and can be formed inexpensively using only glass-free resin. For instance, the dielectric member  10  can be formed with resin such as polytetrafluoroethylene (PTFE), polyphenylether (PPE), and the like, that have excellent processibility and mechanical properties. 
     As shown in  FIG. 4  and  FIG. 5 , the antenna pattern  30  that forms the transceiving loop antenna is formed on the film substrate  20  by a printing means. The film substrate  20  is composed of a flexible thermoplastic material. Polyethylene terephthalate (hereinafter, “PET”), polyimide (PI), polyethylene naphthalate (PEN), and polyvinyl chloride (PVC) can be used as material for the film substrate  20 . 
     Taking into account the processibility, insulative properties, mechanical strength, and the cost, PET is the most suitable material for the film substrate  20 . The dimensions of the film substrate are in proportion to the dielectric member  10  such that the loop antenna can be formed by means of the antenna pattern  30 . 
     The antenna pattern  30  is formed by silk screen printing a conductive paste over the film substrate  20 . The film substrate  20  includes the chip pads  32  on which the IC chip  40  is connected and that electrically connect the IC chip  40  to the antenna pattern  30 . The chip pads  32  are simultaneously formed along with the antenna pattern  30  by silk screen printing the conductive paste on the film substrate  20 . Using the RFID tag  5  having a structure according to the second embodiment a larger current loop than by conventional technology can be obtained, resulting in increased communication distance. The principle of formation of the large current loop is the same as described in the first embodiment and hence not described here. 
     The manufacturing method of the RFID tag  5  is explained next. The film substrate  20  that includes the antenna pattern  30  is wrapped around the dielectric member  10  by bending at folds  22  corresponding to the edges of the dielectric member  10 . The film substrate  20  is secured to the dielectric member  10  by means of an adhesive or a two-sided tape. The loop antenna is thus formed. This is the loop antenna formation step in the manufacturing method of the RFID tag  5 . 
     The IC chip  40  mounting step is carried out next. In other words, the IC chip  40  is mounted in such a way that the chip electrodes of the IC chip  40  are electrically connected to the chip pads  32 . A flip chip mount can be used as the mounting means. 
     Thus, apart from having an identical effect as the first embodiment, the RFID tag  5  according to the second embodiment of the present invention can be easily and inexpensively manufactured by wrapping the film substrate  20  that includes the antenna pattern  30  around the inexpensive dielectric member  10  having a good processibility and by mounting the IC chip  40  on the chip pads  32 . 
     Though a rectangular dielectric member  10  has been used in the RFID tag  5  according to the first embodiment, apart from rectangular shape, the dielectric member  10  may be, for instance, cylindrical, triangular prism, spherical, etc., depending on the article it is intended for. 
     For instance, as shown in  FIG. 6 , the film substrate  20  may be wrapped around a cylindrical dielectric member  10 . As shown in  FIG. 7  and  FIG. 8 , the film substrate  20  may be wrapped around a triangular prism-shaped dielectric member  10 . The effect produced in all the above case will be the same as for the second embodiment.  FIG. 6 ,  FIG. 7 , and  FIG. 8  are perspective views of RFID tags having different shapes. 
       FIG. 9  is a perspective view of the RFID tag according to a third embodiment of the present invention.  FIG. 10  is a top view of the film substrate. As shown in  FIG. 9  and  FIG. 10 , the chip pad  32  is provided parallel to the length of the antenna pattern  30  in such a way that the position of the feeding point of the IC chip  40  can be adjusted. 
     In other words, the chip pad  32  is connected to the antenna pattern  30  by a connector  32   a  and is provided parallel to the antenna pattern  30 . The chip pad  32  and the connector  32   a  are composed of the same material as the antenna pattern  30  and are simultaneously formed when the antenna pattern  30  is printed on the film substrate  20 . 
     As shown in  FIG. 9 , the film substrate  20  is wrapped around and secured to the dielectric member  10  in such a way that the antenna pattern  30  functions as a patch antenna. The IC chip  40  is mounted after the film substrate  20  is secured to the dielectric member  10  and the position of the feeding point is adjusted. 
     In other words, the position of the feeding point is adjusted by electrically connecting the chip electrode of the IC chip  40  to the chip pad  32  and the antenna pattern  30 , sliding the IC chip  40  along the length (that is, in the direction of the arrow shown in the drawing) of the chip pad  32 , and changing the mounting location of the IC chip  40 . 
     Once the position of the feeding point is adjusted, the IC chip  40  is mounted there. As in the second embodiment, a flip chip mount can be used as the mounting means. 
     Thus, apart from having an identical effect as the second embodiment, the RFID tag  5  according to the third embodiment of the present invention allows the antenna response to be adjusted by adjusting the position of the feeding point by changing the mounting location of the IC chip  40 . 
       FIG. 11  is a perspective view of the RFID tag according to a fourth embodiment of the present invention.  FIG. 12  is a top view of the film substrate. Though the antenna pattern  30  is actually on the underside of the film substrate  20 , to facilitate explanation, the antenna pattern  30  is shown in  FIG. 12  in X-ray view (that is, as appearing to be on the surface of the film substrate  20 ). 
     As in the third embodiment, in the fourth embodiment too the chip pad  32  is provided on the film substrate  20  in such a way that the position of the feeding point can be easily adjusted by changing the mounting location of the IC chip  40 . In other words, as shown in  FIG. 11  and  FIG. 12 , an inverted T-shaped film substrate extension  20   a  is provided from the film substrate  20  and the chip pad  32  is set on the film substrate extension  20   a  along the length of and parallel to the antenna pattern  30  in such a way that the position of the feeding point of the IC chip  40  to the antenna pattern  30  can be adjusted. 
     As shown in  FIG. 11 , the film substrate  20  and the film substrate extension  20   a  are wrapped around and secured to the dielectric member  10  in such a way that the antenna pattern  30  functions as a patch antenna. The rest of the structure of the RFID tag and the method of adjustment of the mounting location of the IC chip  40  are identical to those according to the third embodiment and hence are not described here. 
     Thus, apart from having an identical effect as the second embodiment, the RFID tag  5  according to the fourth embodiment of the present invention allows the antenna response to be adjusted by adjusting the position of the feeding point by changing the mounting location of the IC chip  40 . 
       FIG. 13  is a perspective view of the RFID tag according to a fifth embodiment of the present invention. In the fifth embodiment, a depressed portion  10   a  is provided on a surface of the dielectric member  10  and the film substrate  20  is fit in it. This configuration facilitates alignment of the film substrate  20  with the dielectric member  10 . 
     The depth of the depressed portion  10   a  is substantially equal to the sum of the thickness of the film substrate  20  and the thickness of the IC chip  40 . In other words, the surface of the mounted IC chip  40  sits in the depressed portion  10   a  without jutting out of the surface of the dielectric member  10 . The rest of the structure and the manufacturing method of the RFID tag  5  is identical to that of the RFID tag  5  according to the second embodiment, and hence are not described here. 
     Thus, apart from having an identical effect as the second embodiment, the RFID tag  5  according to the fifth embodiment of the present invention allows the film substrate  20  to be easily aligned with the dielectric member  10  by providing the depressed portion  10   a  on the dielectric member  10 . 
     Since the surface of the mounted IC chip  40  sits in the concave portion  10   a  and does not jut out of the surface of the dielectric member  10 , when secured to an article such as a wave-absorbing material and is covered with the protection film the RFID tag  5  remains safe without any pressure being transferred to it. Consequently, the durability of the RFID tag  5  against external pressure is enhanced. 
     Further, this flat RFID tag  5  is ideal for using on the inner lining of clothing and apparel since it does not poke when coming in contact with the body. 
     The fifth embodiment can be applied to all the embodiments that follow (in case of a ninth embodiment, which is described later, a depressed portion having the same functions as the depressed portion  10   a  may be provided on a dielectric member support  60 , which is described later). However, all the embodiments produce the same effect. 
       FIG. 14  is a perspective view of the RFID tag according to a sixth embodiment of the present invention.  FIG. 15  is a perspective view of the RFID tag in which the IC chip is mounted on the chip pads formed on the dielectric member. As shown in  FIG. 15 , in the RFID tag  5  according to the fifth embodiment of the present invention, chip pads  12  are already provided on the side of the dielectric member  10  and the IC chip  40  is mounted on the chip pads  12 . As shown in  FIG. 14 , the film substrate  20  is wrapped around the dielectric member  10  in such a way that the antenna pattern  30  printed on the bottom surface (underside) of the film substrate  20  is electrically connected to the chip pads  12 . 
     The chip pads  12  can be formed on the dielectric member  10  by etching copper, by printing a conductive ink, or by pasting a conductive material. The connection of the chip pads  12  to the antenna pattern  30  and securing of one to the other can be done by applying a conductive adhesive (silver paste) on the contact surfaces of the chip pads  12  and the antenna pattern  30  and then applying pressure and heat on the portion. The mounting method of the IC chip  40  and the wrapping method of the film substrate  20  are identical to those according to the second embodiment, and hence are not described here. 
     Thus, apart from having an identical effect as the second embodiment, the RFID tag  5  according to the sixth embodiment of the present invention allows the selection of the film substrate  20  that includes the antenna pattern  30  most suited to the mounted IC chip  40 , thus enabling adjustment of the transmission and reception response. 
       FIG. 16  is a perspective view of the RFID tag according to a seventh embodiment of the present invention.  FIG. 17  is a top view of the film substrate. As shown in  FIG. 16 , the IC chip  40  is mounted on a side surface of the dielectric member  10 . In other words, the IC chip  40  is mounted in such a location that a bulge due to the presence of the IC chip  40  is avoided in the largest plane portion of the RFID tag  5 . 
     Thus, as shown in  FIG. 17 , the film substrate  20  is formed in such a way that the IC chip  40  can be mounted on the side surface of the dielectric member  10 . In other words, when the film substrate  20  is wrapped around the dielectric member  10 , a pair of film substrate extensions  20   b  of the film substrate  20  and a pair of chip pads  32  extend towards a side of the dielectric member  10 . 
     The chip pads  32  are printed on the film substrate extensions  20   b  in continuity with the antenna pattern  30 . The mounting method of the IC chip  40  and the wrapping method of the film substrate  20  are identical to those according to the second embodiment, they are not described here. 
     Thus, apart from having an identical effect as the second embodiment, the RFID tag  5  according to the seventh embodiment, the IC chip  40  is mounted on a side surface of the dielectric member  10 . Consequently, a bulge due to the presence of the IC chip  40  is avoided in the largest plane portion of the RFID tag  5 . 
     Further, as in the fifth embodiment, setting the IC chip  40  on the side surface makes the RFID tag  5  safe without any pressure being transferred to it when secured to an article and covered with the protection film. Consequently, the durability of the RFID tag  5  against external pressure is enhanced. Further, this flat RFID tag  5  is ideal for using on the inner lining of clothing and apparel since it does not poke when coming in contact with the body. 
     Though a rectangular dielectric member  10  has been used in the RFID tag  5  according to the seventh embodiment, the dielectric member  10  may be of any shape (for instance, cylindrical, triangular prism, spherical, etc.) depending the article it is intended for. 
     For instance, as shown in  FIG. 18 , the film substrate  20  may be wrapped around a cylindrical dielectric member  10  and the IC chip  40  is provided on the disk portion of the cylinder.  FIG. 18  is a perspective view of an RFID tag having a different shape. 
       FIG. 19  is a perspective view of the RFID tag according to an eighth embodiment of the present invention. In the REID tag  5  according to the eighth embodiment of the present invention, a concavity  10   b  into which the IC chip  40  can be accommodated is provided on the dielectric member  10  and the IC chip  40  is set in the concavity  10   b . The film substrate  20  is wrapped around the dielectric member  10  in such a way that and the IC chip  40  is electrically connected to the antenna pattern  30  formed on the underside of the film substrate  20 . In other words, the RFID tag  5  is fabricated in such a way that the IC chip  40  does not jut out of the surface of the RFID tag  5 . 
     Bumps  50  are provided on the chip electrodes (not shown) of the IC chip  40 . The IC chip  40  is fixed to the bottom of the concavity  10   b , with the bumps  50  facing upward, by means of a thermosetting adhesive or an instant adhesive. The IC chip  40  is covered with an underfill  52  so as to keep the IC chip  40  and the bumps  50  securely held and protected. The film substrate  20  is wrapped and secured around the dielectric member  10  in such a way that the antenna pattern  30  and the bumps  50  of the IC chip  40  are electrically connected. 
     The connection of the bumps  50  with the antenna pattern  30  and the securing of one to the other can be done by applying the conductive adhesive (silver paste) on the contact surfaces of the bumps  50  and the antenna pattern  30  and then applying pressure and heat on the portion. 
     Thus, apart from having an identical effect as the second embodiment, the RFID tag  5  according to the eighth embodiment of the present invention has a plane surface since the IC chip  40  fits inside the concavity  10   b  of the dielectric member  10   
     Further, as in the fifth embodiment, accommodating the IC chip  40  makes the RFID tag  5  safe without any pressure being transferred to it when secured to an article and covered with the protection film. Consequently, the durability of the RFID tag  5  against external pressure is enhanced. Further, this flat RFID tag  5  is ideal for using on the inner lining of clothing and apparel since it does not poke when coming in contact with the body. 
     In the eighth embodiment, the film substrate  20  is wrapped around the dielectric member  10  in such a way that the concavity  10   b  is in aligned against the length edge of the film substrate  20 . However, the film substrate  20  may be wrapped around the dielectric member  10  in such a way that the concavity  10   b  is in aligned against the width edge of the film substrate  20 . 
       FIG. 20  is a perspective view of the RFID tag according to the ninth embodiment of the present invention.  FIG. 21  is a perspective view of the RFID tag in which the dielectric member is secured to a dielectric member support. As shown in  FIG. 20 , the RFID tag  5  according to the ninth embodiment includes the dielectric member  10 , the dielectric member support  60  that slidably supports the dielectric member  10 , the film substrate  20  that is wrapped around the surface of the dielectric member  10  and including the antenna pattern  30 , and the IC chip  40  that is electrically connected to the antenna pattern  30 . 
     The dielectric member support  60 , which may be composed of resin, such as plastic, has a slot  62  for sliding the dielectric member  10  in and out of. The dielectric constant of the dielectric member is adjusted by sliding the dielectric member  10  in the dielectric member support  60  in the direction of the arrow shown in  FIG. 20 . The response of the antenna can be adjusted easily by adjusting the dielectric constant. 
     As shown in  FIG. 21 , the dielectric member  10  and the dielectric member support  60  are secured with an adhesive  70  to maintain the position of the adjusted dielectric member  10 . As shown in  FIG. 21 , the dielectric member  10  can be secured by applying the adhesive  70  on edge at the opening of the slot  62 . The adhesive may be applied inside the slot  62  instead of at the opening. 
     Further, a notch means may be used as a securing means wherein a lug and notches that engage into each other may be provided and the position of engagement may be changed by application of a certain degree of external pressure. The mounting method of the IC chip  40  and the wrapping method of the film substrate  20  are identical to those described in the second embodiment, and hence are not described here. 
     Thus, apart from having an identical effect as the second embodiment, the RFID tag  5  according to the ninth embodiment of the present invention allows adjustment of the dielectric constant, and hence the response of the antenna, by sliding the dielectric member  10  in and out of the dielectric member support  60 . 
     Moreover, the RFID tag can be easily inactivated (that is, communication can be disabled). To inactivate the RFID tag  5  all a user needs to do is remove the adhesive  70  and remove the dielectric member  10  from the dielectric member support  60 . 
       FIG. 22  is a perspective view of the RFID tag according to a tenth embodiment of the present invention. The dielectric member  10  is composed of a plurality of dielectric members  10 A and  10 B, that have different dielectric constants and dielectric losses in order to adjust the dielectric constant and a dielectric loss. 
     For instance, when the dielectric member  10 A with a high dielectric constant and dielectric loss and the dielectric member  10 B with a low dielectric constant and dielectric loss are combined (the dielectric members  10 A and  10 B are integrated by gluing them together), the dielectric member  10  with intermediate properties can be obtained. 
     The dielectric members  10 A and  10 B are combined horizontally in  FIG. 22 . However, the dielectric members  10 A and  10 B may also be combined vertically (that is, in the thickness direction of the dielectric members). The mounting method of the IC chip  40  and the wrapping method of the film substrate  20  are identical to those described in the second embodiment, and hence not described here. 
     Thus, apart from having an identical effect as the second embodiment, the RFID tag  5  according to the tenth embodiment of the present invention allows adjustment of the dielectric constant and the dielectric loss, and hence the response of the antenna, by using the dielectric member  10  formed by combing dielectric members  10 A and  10 B having different dielectric constants and dielectric losses. 
     The tenth embodiment can also be applied to first through eighth embodiments as well as a twelfth embodiment described later to produce identical effect. 
       FIG. 23  is a perspective view of the RFID tag according to an eleventh embodiment of the present invention. The RFID tag  5  according to the eleventh embodiment has a structure similar to the RFID tag  5  according to the second embodiment except that the dielectric member  10  has an airspace  80 . The airspace  80  is a vacant space that forms a layer of air of predetermined thickness within the dielectric member  10 . In other words, the dielectric constant in the dielectric member  10  can be reduced and set to the desired value by the dielectric constant of the air in the airspace  80 . 
     Thus, apart from having an identical effect as the second embodiment, the RFID tag  5  according to the eleventh embodiment of the present invention allows antenna response to be easily adjusted by adjusting the dielectric constant of the dielectric member  10  by increasing or decreasing the airspace  80  within the dielectric member  10 . 
     The eleventh embodiment is explained by taking the RFID tag  5  according to the second embodiment and providing the airspace  80  in the dielectric member  10 . It is also possible to provide the airspace  80  in the dielectric member  10  of the RFID tag  5  according to any of the first embodiment, third to eighth embodiments, and the twelfth embodiment explained next. 
       FIG. 24  is a cross-sectional view of the RFID tag according to a twelfth embodiment of the present invention.  FIG. 25  is a cross-sectional view of the RFID tag to illustrate a lamination step. In the eighth embodiment of the present invention, the RFID tag  5  is formed by mounting the IC chip  40  on the concavity  10 B of the dielectric member  10  and a single sheet of the film substrate  20  is wrapped around the dielectric member  10  to form folds  22 , as shown in  FIG. 19 . 
     However, in the twelfth embodiment, the RFID tag  5  is fabricated by laminating the surface and the underside of the dielectric member  10  by two separate film substrates  20 , as shown in  FIG. 24  and  FIG. 25 . 
     In other words, the manufacturing method of the RFID tag  5  includes two steps, namely the IC chip mounting process and the lamination process. The IC chip mounting process involves electrically connecting the antenna pattern  30  of a first film substrate  20  to the IC chip  40 . The lamination process involves fixing the first film substrate  20  on the surface (a first surface) of the dielectric member  10  in such a way that the IC chip  40  sits in the concavity  10   b  of the dielectric member  10 , fixing a second film substrate  20  on the underside (a second surface) of the dielectric member  10 , and forming the loop antenna by electrically connecting the two antenna patterns  30  of two film substrates  20  by means of a conductive adhesive (conductive member)  24 , such as silver paste. 
     The flip chip mount can be used in the IC chip mounting step. The lamination of the two film substrates  20  and the connection of the antenna patterns  30  in the lamination step are carried out by applying pressure and heat on the portion having the conductive adhesive  24 , as indicated by the arrows in  FIG. 25 . Though not shown, adhesive is used on the contact surfaces of the dielectric member  10  and the film substrate  20  other than in the portions where the conductive adhesive  24  is provided. 
     Thus, apart from having an identical effect as the eighth embodiment, the lamination of the film substrates  20  and the connection of the antenna patterns  30  in the lamination step in the RFID tag  5  according to the twelfth embodiment of the present invention can be done more easily than wrapping the film substrate  20  around the dielectric member  10  as in the eighth embodiment. 
     Since the IC chip  40  is laminated by the film substrates  20 , the need to provide a special lamination (protection film) to protect the RFID tag  5  is obviated, reducing the number of components. 
     According to the present invention, a loop antenna is formed on a surface of a dielectric member. Consequently, the transmission gain of the antenna can be enhanced and communication distance can be increased. Moreover, since an antenna pattern is formed around the dielectric member, the antenna pattern does not get damaged even when subjected to external pressure, ensuring a reliable communication. 
     According to the present invention, a film substrate is provided that forms the loop antenna by virtue of being mounted on the surface of the dielectric member. Consequently, the loop antenna can be formed easily and inexpensively, the transmission gain of the loop antenna can be enhanced, and the communication distance can be increased. Further, since the film substrate, which includes the antenna pattern, is formed on the dielectric member, the antenna pattern does not get damaged even when subjected to external pressure, ensuring a reliable communication. 
     According to the present invention, the mounting of an IC chip and its connection to the antenna pattern can be realized simultaneously and with ease. 
     According to the present invention, the mounting of an IC chip and its connection to the antenna pattern can be realized simultaneously and with ease. 
     According to the present invention, the mounted IC chip sits inside a concavity provided in the dielectric member without jutting out of the surface of the dielectric member. Consequently, the IC chip remains safe against external pressure and the RFID tag is not easily damaged. 
     According to the present invention, the surfaces other than the side surface on which the IC chip is mounted are plane. Consequently, the IC chip remains safe against external pressure and the RFID tag is not easily damaged. 
     According to the present invention, the position of a feeding point can be adjusted easily by changing the mounting location of the IC chip on the chip pad. Consequently, the response of the antenna can be adjusted. 
     According to the present invention, the response of the antenna can be easily adjusted by sliding the dielectric member in and out of a dielectric member support. 
     According to the present invention, the antenna response can be adjusted by adjusting the dielectric constant and the dielectric loss by combining a plurality of dielectric members having different dielectric constants and dielectric losses. 
     According to the present invention, the loop antenna can be easily formed by mounting the film substrate on the surface of the dielectric member using a loop antenna formation step. The RFID can be easily and inexpensively manufactured by mounting the IC chip on the loop antenna using an IC chip mounting step. 
     Although the invention has been described with respect to a specific embodiment for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art which fairly fall within the basic teaching herein set forth.