Patent Publication Number: US-2022237427-A1

Title: Rfic module and rfid tag

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of PCT/JP2020/034003 filed Sep. 8, 2020, which claims priority to Japanese Patent Application No. 2019-227113, filed Dec. 17, 2019, the entire contents of each of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a radio frequency integrated circuit (RFIC) module and a radio frequency identifier (RFID) tag including the RFIC module. 
     BACKGROUND 
     An RFID system including an RFID tag attached to an article and a reader/writer that performs reading and writing for the RFID tag is used as an article information management system. 
     WO 2016/084658 A (hereinafter “Patent Literature 1”) discloses an RFID tag including a conductor acting as an antenna and an RFIC module coupled to the conductor. 
     The RFID tag disclosed in Patent Literature 1 includes an RFIC chip that stores predetermined information and processes a predetermined radio signal, and an antenna element (e.g., a radiator) that transmits and receives a high-frequency signal, and is used by being affixed to various articles or packaging materials thereof to be managed. 
     There are a variety of articles to be managed, and its range is expanding. However, in the case of a small-sized article, the RFID tag is relatively large with respect to the article, and in some cases, an attaching method of the RFID tag to the article is an issue. 
     In addition, the RFIC is mounted on the RFIC module used for the RFID tag, and the electrical characteristics of the RFIC may differ depending on the IC manufacturer. In this case, it is necessary to properly select an impedance matching circuit suitable for each RFIC to be used. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide an RFIC module with a downsized RFID tag, and an RFID tag including the RFIC module. Moreover, it is an object of the present invention to provide an RFIC module that easily copes with a difference in electrical characteristics of RFIC to be used, and an RFID tag including the RFIC module. 
     In an exemplary aspect, an RFIC module is provided that includes a base material including a first face and a second face opposite to each other, an RFIC mounted near and/or above the first face of the base material, and an RFIC-side terminal electrode provided on the first face of the base material and connected to the RFIC. Moreover, an insulator film is provided on a surface of the RFIC-side terminal electrode, and a conductor film facing the RFIC-side terminal electrode is provided on the insulator film. 
     With this configuration, a capacitance is formed between the RFIC-side terminal electrode and the conductor film facing each other with the insulator film interposed therebetween, and the capacitance is connected to the RFIC. Therefore, such a structure is configured to act as the RFIC to which the capacitance is added, the inductance component required for the impedance matching unit between the RFIC and the antenna can be reduced, and thereby the RFID tag can be downsized as a whole. In addition, for example, even when an RFIC having a different internal capacitance component is used for each manufacturer, desired electrical characteristics can be obtained only by changing the conductor film according to the capacitance component. 
     In an exemplary aspect, an antenna-side terminal electrode can be provided on the second face of the base material, and an interlayer connection conductor connecting the RFIC-side terminal electrode and the antenna-side terminal electrode can be provided on the base material. 
     Moreover, an RFIC module in an exemplary aspect includes a base material including a first face and a second face opposite to each other, an RFIC mounted near and/or above the first face of the base material, and an RFIC-side terminal electrode provided on the first face of the base material and connected to the RFIC. Moreover, a conductor film facing the RFIC-side terminal electrode is provided on the second face of the base material. 
     In yet another exemplary aspect, an RFID tag is provided that includes an antenna and an RFIC module. The antenna includes an antenna base material and an antenna conductor pattern provided on the antenna base material, and the RFIC module includes the above described configuration(s). 
     According to the exemplary aspects of the present invention, an RFIC module with reduced size of an RFID tag and an RFID tag including the RFIC module are obtained. In addition, according to the present invention, an RFIC module and be provided that easily copes with a difference in electrical characteristics of RFIC to be used and an RFID tag including the RFIC module is also provided. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1A  is a plan view of an RFIC module  101  according to a first exemplary embodiment, and  FIG. 1B  is a longitudinal sectional view taken along line X-X in  FIG. 1A . 
         FIG. 2A  is a plan view of the RFIC module  101  mounted on an antenna  30 .  FIG. 2B  is a longitudinal sectional view taken along line X-X in  FIG. 2A . 
         FIG. 3  is a partial equivalent circuit diagram in a state where the RFIC module  101  is mounted on the antenna  30 . 
         FIG. 4A  is a perspective view of an RFID tag  201 .  FIG. 4B  is a perspective view before the RFIC module  101  is mounted on an antenna  30 . 
         FIG. 5  is a circuit diagram illustrating a relationship between an RFIC  2 , an impedance matching circuit  7 , and antenna conductors  32   a  and  32   b.    
         FIG. 6  is a diagram illustrating two resonance frequencies generated by the impedance matching circuit. 
         FIG. 7A  is a plan view of an RFIC module  102  according to a second exemplary embodiment, and  FIG. 7B  is a longitudinal sectional view taken along line X-X in  FIG. 7A . 
         FIG. 8A  is a plan view of the RFIC module  102  mounted on the antenna  30 .  FIG. 8B  is a longitudinal sectional view taken along line X-X in  FIG. 8A . 
         FIG. 9  is a longitudinal sectional view of an RFIC module  103  according to a third exemplary embodiment. 
         FIG. 10  is a partial equivalent circuit diagram in a state where the RFIC module  103  is mounted on an antenna. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Hereinafter, a plurality of exemplary aspect of the present invention will be described with some specific examples with reference to the drawings. In the drawings, the same portions are denoted by the same reference numerals. In consideration of the description of the main points or ease of understanding, the exemplary embodiment is divided into a plurality of embodiments/aspects for convenience of description, but partial replacement or combination of configurations shown in different embodiments is possible in alternative aspects. In the second and subsequent embodiments, descriptions of matters common to the first embodiment will be omitted, and only different points will be described. Specifically, the same operation and effect by the same configuration will not be sequentially mentioned for each subsequent embodiment. 
     First Exemplary Embodiment 
       FIG. 1A  is a plan view of an RFIC module  101  according to the first exemplary embodiment, and  FIG. 1B  is a longitudinal sectional view taken along line X-X in  FIG. 1A . 
     As shown, the RFIC module  101  includes a base material  1  having a first face S 1  and a second face S 2  opposite to each other, an RFIC  2  mounted near and/or above the first face S 1  of the base material  1 , and RFIC-side terminal electrodes  11  and  12  which are formed on the first face S 1  of the base material  1  and to which the RFIC  2  is connected. In an exemplary aspect, the base material  1  is, for example, a sheet of polyethylene terephthalate (PET) or polyimide (PI). Moreover, the RFIC-side terminal electrodes  11  and  12  are, for example, patterned Cu foils. 
     An insulator film  3  is formed on the surface of each of the RFIC-side terminal electrodes  11  and  12 . In this example, an opening is formed in the insulator film  3  to define a mounting position of the RFIC  2 . A conductor film  4  is formed on the insulator film  3 . The conductor film  4  includes conductor films  41  and  42  facing the RFIC-side terminal electrodes  11  and  12 , and a conductor film  43  connecting the conductor film  41  and the conductor film  42 . The insulator film  3  is, for example, various resist films of epoxy type, polyester type, or the like, and is formed by, for example, printing. Furthermore, the conductor film  4  is formed by printing and heating and curing Ag paste. Alternatively, conductor film  4  is formed by Cu plating in another exemplary aspect. 
     The RFIC  2  has two terminal electrodes that are connected to the RFIC-side terminal electrodes  11  and  12  by soldering or the like. Since the RFIC-side terminal electrode  11  and the conductor film  41  face each other with the insulator film  3  interposed therebetween, capacitance is generated between the RFIC-side terminal electrode  11  and the conductor film  41 . Similarly, since the RFIC-side terminal electrode  12  and the conductor film  42  face each other with the insulator film  3  interposed therebetween, capacitance is generated between the RFIC-side terminal electrode  12  and the conductor film  42 . 
       FIG. 2A  is a plan view of an RFIC module  101  mounted on an antenna  30 .  FIG. 2B  is a longitudinal sectional view taken along line X-X in  FIG. 2A . The antenna  30  includes an antenna base material  31  and a conductor pattern formed on the antenna base material  31 . The entire conductor pattern formed on the antenna base material  31  will be described later. 
     In  FIGS. 2A and 2B , the ends of antenna conductors  32 LPa and  32 LPb face each other along the face of the antenna base material  31 . The RFIC module  101  is mounted at a position where the antenna conductors  32 LPa and  32 LPb face each other. In this example, the lower face of the RFIC module  101  (i.e., the lower face of the base material  1 ) is bonded on the antenna base material  31  (i.e., on the antenna conductors  32 LPa and  32 LPb) via a bonding material  40 . The bonding material  40  is, for example, an insulating adhesive in an exemplary aspect. 
     Since the base material  1  is thicker than the bonding material  40 , variations in the values of capacitances Ca and Cb generated when the RFIC-side terminal electrodes  11  and  12  and the antenna conductors  32 LPa and  32 LPb face each other can be adjusted not by the thickness of the bonding material  40 , but by the thickness of the base material  1 . Since the thickness of the base material  1  can be adjusted by about ±1 μm, variations in the values of the capacitances Ca and Cb can be easily reduced/adjusted. This enables antenna design in consideration of the capacitances Ca and Cb, and enables antenna design even when the values of the capacitances Ca and Cb are reduced. Specifically, the planar outer dimension of the RFIC module  101  can be reduced to about 3.2×2.5 mm, and the values of the capacitances Ca and Cb can be set to 2 pF or less. Such downsizing of the RFIC module  101  enables the RFIC module  101  to be mounted on the antenna  30  with a chip mounter. This significantly improves the mounting speed of the RFIC module  101 . 
       FIG. 3  is a partial equivalent circuit diagram in a state where the RFIC module  101  is mounted on the antenna  30 . Additional capacitances Cca and Ccb are connected via the conductor film  4  between two terminals of the RFIC  2 . The additional capacitances Cca and Ccb are capacitances generated between the RFIC-side terminal electrodes  11  and  12  and the conductor film  4 . Capacitances Ca and Cb are connected between the two terminals of the RFIC  2  and the antenna conductors  32 LPa and  32 LPb, respectively. As described above, the capacitances Ca and Cb are capacitances generated between the RFIC-side terminal electrodes  11  and  12  and the antenna conductors  32 LPa and  32 LPb, respectively. 
     There is an equivalent capacitance Cp between the two terminals of the RFIC  2 . The series circuit of the additional capacitances Cca and Ccb is connected in parallel to the capacitance Cp. Therefore, the capacitance between the two terminals of the RFIC increases by the series combined capacitance due to the presence of the additional capacitances Cca and Ccb. 
       FIG. 4A  is a perspective view of an RFID tag  201 .  FIG. 4B  is a perspective view before the RFIC module  101  is mounted on the antenna  30 . The RFID tag  201  is configured by mounting the RFIC module  101  on the antenna  30 . 
     The antenna  30  includes an antenna base material  31  and an antenna conductor pattern  32  formed on the antenna base material  31 . The antenna conductor pattern  32  includes belt-shaped antenna conductors  32   a  and  32   b  and a loop-shaped antenna conductor  32 LP partially having a cutout portion CT. In  FIGS. 4A and 4B , two broken lines are virtual lines indicating boundaries between the antenna conductors  32   a  and  32   b  and the antenna conductor  32 LP. In an exemplary aspect, antenna base material  31  is a flexible insulator sheet made of, for example, polyethylene terephthalate (PET) resin or polyphenylene sulfide (PPS) resin. The antenna conductor pattern  32  is a thin conductor exhibiting flexibility, such as an aluminum foil or a copper foil. 
     The length of the loop-shaped antenna conductor  32 LP in the X direction is larger than the length of the RFIC module  101 . The loop-shaped antenna conductor  32 LP acts as an inductor for impedance matching. 
       FIG. 5  is a circuit diagram illustrating a relationship between the RFIC  2 , the impedance matching circuit  7 , and the antenna conductors  32   a  and  32   b .  FIG. 6  is a diagram illustrating two resonance frequencies generated by the impedance matching circuit. 
     The antenna conductor  32 LP illustrated in  FIG. 4B  can be equivalently represented by the impedance matching circuit  7  illustrated in  FIG. 5 . As described above, the RFIC  2  has a parasitic capacitance Cp due to the internal circuit, the stray capacitance, and the like. As illustrated in  FIG. 6 , two resonances occur in a state where the impedance matching circuit  7  is connected to the RFIC  2 . The first resonance is a resonance generated in a current path including the antenna conductors  32   a  and  32   b , an inductor L 3 , and an inductor L 4 , and the second resonance is a resonance generated in a current path (e.g., a current loop) including the inductors L 1  to L 4 , the capacitances Ca, Cb, Cca, and Ccb, and the parasitic capacitance Cp. The two resonances are coupled by inductors L 3  and L 4  shared by the respective current paths, and two currents i 1  and i 2  respectively corresponding to the two resonances flow as shown in  FIG. 5 . 
     In operation, both the first resonance frequency and the second resonance frequency are affected by the inductors L 3  and L 4 . A difference of several 10 MHz (specifically, about 5 to 50 MHz) is generated between the first resonance frequency and the second resonance frequency. These resonance frequency characteristics are expressed by a curve A and a curve B in  FIG. 6 . By coupling the two resonances having such resonance frequencies, broadband resonance frequency characteristics as indicated by a curve C in  FIG. 6  are obtained. 
     The additional capacitances Cca and Ccb illustrated in  FIG. 5  are capacitances generated between the RFIC-side terminal electrodes  11  and  12  and the conductor film  4 , and the capacitances Ca and Cb are capacitances generated between the two terminals of the RFIC  2  and the antenna conductors  32 LPa and  32 LPb. That is,  FIG. 5  is a diagram represented by including the impedance matching circuit  7  in the equivalent circuit illustrated in  FIG. 3 . 
     With the above-described configuration, the additional capacitances Cca and Ccb are connected to the RFIC  2 . Therefore, the loop size of the antenna conductor  32 LP required to obtain the predetermined resonance frequency characteristic can be reduced by adding the additional capacitances Cca and Ccb, and the RFID tag  201  can be downsized as a whole accordingly. In addition, for example, even when the RFIC  2  having different internal capacitance components is used for each manufacturer, it is possible to obtain desired electrical characteristics only by changing the additional capacitances Cca and Ccb according to the parasitic capacitance Cp. The capacitances of the additional capacitances Cca and Ccb can be determined by the areas of the conductor films  41  and  42 , or by the thickness of the insulator film  3  or further by the dielectric constant of the insulator film  3 . Further, after the conductor films  41  and  42  are formed, the additional capacitances Cca and Ccb can be finely adjusted by trimming in an exemplary aspect. 
     Second Exemplary Embodiment 
     In the second exemplary embodiment, an RFIC module tag and an RFID tag having a formation position of an additional capacitance different from that of the first embodiment will be exemplified. 
       FIG. 7A  is a plan view of an RFIC module  102  according to the second embodiment, and  FIG. 7B  is a longitudinal sectional view taken along line X-X in  FIG. 7A . 
     The RFIC module  102  includes a base material  1  having a first face S 1  and a second face S 2  opposite to each other, an RFIC  2  mounted near and/or above the first face S 1  of the base material  1 , and RFIC-side terminal electrodes  11  and  12  which are formed on the first face S 1  of the base material  1  and to which the RFIC  2  is connected. 
     An insulator film  3  having a predetermined thickness is formed on the entire surface of the first face S 1  of the base material  1 . As shown in this embodiment, a conductor film  4  is formed on the second face S 2  of the base material  1 . Therefore, the conductor film  4  faces the RFIC-side terminal electrodes  11  and  12  via the base material  1 . The conductor film  4  is formed by printing and heating and curing Ag paste. Alternatively, conductor film  4  is formed by Cu plating. Other configurations are as described in the first embodiment and not repeated herein. 
     Since the RFIC-side terminal electrodes  11  and  12  and the conductor film  4  face each other with the base material  1  interposed therebetween, additional capacitances Cca and Ccb are generated between the RFIC-side terminal electrodes  11  and  12  and the conductor film  4 , respectively. 
       FIG. 8A  is a plan view of the RFIC module  102  mounted on the antenna  30 .  FIG. 8B  is a longitudinal sectional view taken along line X-X in  FIG. 8A . The antenna  30  includes an antenna base material  31  and a conductor pattern formed on the antenna base material  31 . The conductor pattern formed on the antenna base material  31  is as described in the first embodiment. 
     In  FIGS. 8A and 8B , the RFIC module  102  is mounted such that the RFIC-side terminal electrodes  11  and  12  face the antenna conductors  32 LPa and  32 LPb, respectively. In this example, the surface of the insulator film  3  of the RFIC module  102  is bonded on the antenna base material  31  (i.e., on the antenna conductors  32 LPa and  32 LPb) via the bonding material  40 . The bonding material  40  is, for example, an insulating adhesive. 
     In this manner, the additional capacitances Cca and Ccb can be formed at positions between which the base material  1  is interposed. 
     Third Exemplary Embodiment 
     In the third exemplary embodiment, an RFIC module and an RFID tag in which an antenna conductor and an RFIC  2  are connected to each other via an inductor or directly are illustrated. 
       FIG. 9  is a longitudinal sectional view of an RFIC module  103  according to the third embodiment. The RFIC module  103  includes the base material  1  having the first face S 1  and the second face S 2  opposite to each other, the RFIC  2  mounted near the first face S 1  of the base material  1 , and the RFIC-side terminal electrodes  11  and  12  which are formed on the first face S 1  of the base material  1  and to which the RFIC  2  is connected. As further shown, the insulator film  3  is formed on the surface of each of the RFIC-side terminal electrodes  11  and  12 . Moreover, the conductor film  4  is formed on the insulator film  3 . The antenna-side terminal electrodes  21  and  22  are formed on the second face S 2  of the base material  1 . Interlayer connection conductors V 1  and V 2  respectively connecting the RFIC-side terminal electrodes  11  and  12  and the antenna-side terminal electrodes  21  and  22  are formed inside the base material  1 . 
       FIG. 10  is a partial equivalent circuit diagram in a state where the RFIC module  103  is mounted on an antenna. The additional capacitances Cca and Ccb are connected via the conductor film  4  between two terminals of the RFIC  2 . The additional capacitances Cca and Ccb are capacitances generated between the RFIC-side terminal electrodes  11  and  12  and the conductor film  4 . In addition, the two terminals of the RFIC  2  and the antenna conductors  32   a  and  32   b  are directly connected via a parasitic inductor. 
     In this manner, the RFIC module  103  in which the terminals of the RFIC  2  are drawn out to the antenna-side terminal electrodes  21  and  22  through a conductor can be configured, and the RFID tag in which the RFIC module is connected to the antenna conductor via an inductor or directly can be configured. 
     Finally, it is generally notes that the description of the above-described embodiments is illustrative in all respects and is not restrictive. Modifications and changes can be made as appropriate by those skilled in the art. 
     REFERENCE SIGNS LIST 
     
         
         
           
             Ca, Cb capacitance 
             Cca, Ccb additional capacitance 
             Cp parasitic capacitance 
             L 1  to L 4  inductor 
             S 1  first face 
             S 2  second face 
             V 1 , V 2  interlayer connection conductor 
               1  base material 
               2  RFIC 
               3  insulator film 
               4  conductor film 
               7  impedance matching circuit 
               11 ,  12  RFIC-side terminal electrode 
               21 ,  22  antenna-side terminal electrode 
               30  antenna 
               31  antenna base material 
               32  antenna conductor pattern 
               32   a ,  32   b  antenna conductor 
               32 LP,  32 LPa,  32 LPb antenna conductor 
               40  bonding material 
               41 ,  42 ,  43  conductor film 
               101 ,  102 ,  103  RFIC module 
               201  RFID tag