RFID module

Abstract

This RFID module comprises: a substrate having a first main surface and a second main surface opposite each other; an RFIC chip disposed on the first main surface side of the substrate; and a coil element on which a conductive wire is wound a plurality of times. One end of the RFIC chip is electrically connected to one end of the coil element. The other end of the RFIC chip is electrically connected to the other end of the coil element. The coil element has at least one sparsely wound portion. Both ends of the coil element are first densely wound portions in which the inter-conductive wire pitch is narrower than in the sparsely wound portion.

Description

Technical Field

[0001] The present invention relates to an RFID module having a substrate on which a coil conductor is mounted.

Background Art

[0002] Conventionally, an RFID (Radio-Frequency Identification) module, which is a wireless communication device, is attached to a product for product management. As one form of the RFID module, there is a module in which a coil conductor functioning as an antenna is disposed on an insulating substrate together with an RFIC chip (Radio-Frequency Integrated Circuit).

[0003] For example, Patent Document 1 proposes an RFID module including a coil conductor in which coil elements having legs for mounting are arranged in a row.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the coil conductor of the RFID module disclosed in Patent Document 1, since there are legs for mounting, the coil opening diameter is reduced by the amount of the mounting space. If antenna characteristics are to be ensured, the RFID module becomes large-sized.

[0006] An object of the present invention is to provide an RFID module that can be miniaturized while maintaining antenna characteristics.

Means for Solving the Problems

[0007] An RFID module according to one aspect of the present invention includes a substrate having a first main surface and a second main surface facing each other, an RFIC chip disposed on the first main surface side of the substrate, and a coil element around which a conductor is wound a plurality of times. One end of the RFIC chip is electrically connected to one end of the coil element, and the other end of the RFIC chip is electrically connected to the other end of the coil element. The coil element has at least one sparse winding portion, and both ends of the coil element are first tightly wound portions in which the pitch between conductors is wound more narrowly than in the sparse winding portion.

Advantages of the Invention

[0008] According to the present invention, it is possible to provide an RFID module that can be miniaturized while maintaining antenna characteristics.

Brief Description of the Drawings

[0009]

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Embodiments for Carrying Out the Invention

[0010] The embodiments described below all show specific examples of the present invention, and the present invention is not limited to this configuration. Also, the numerical values, shapes, configurations, steps, order of steps, etc. specifically shown in the following embodiments are examples and do not limit the present invention. Among the components in the following embodiments, components not described in the independent claims indicating the most general concept are described as optional components. Also, in all embodiments, the same applies to the configurations in each modification example, and the configurations described in each modification example may be combined with each other.

[0011] (Embodiment 1) Next, the schematic configuration of the RFID module 1 according to Embodiment 1 of the present invention will be described. FIG. 1 is a longitudinal sectional view of the RFID module 1 according to Embodiment 1. FIG. 2 is a perspective view of the coil element. In the figure, the X - Y - Z coordinate system is for facilitating the understanding of the invention and does not limit the invention. The X - axis direction indicates the longitudinal direction of the RFID module 1, the Y - axis direction indicates the depth (width) direction, and the Z - axis direction indicates the thickness direction. The X, Y, and Z directions are perpendicular to each other. Also, in the embodiment, the positive direction of the Z - axis is described as the upward direction, and the negative direction of the Z - axis is described as the downward direction.

[0012] The RFID module 1 of the embodiment includes a substrate 3, a coil element 5 and an RFIC chip 7 disposed on the first main surface 61 which is the upper surface of the substrate 3, and a resin layer 9 that seals the coil element 5 and the RFIC chip 7. The RFIC chip 7 has a first terminal 7a and a second terminal 7b which are input / output terminals. The substrate 3 in Embodiment 1 is a double - sided substrate, and the second main surface 62 which is the lower surface of the substrate 3 and the first main surface 61 face each other. The substrate 3 is insulating and is, for example, a glass - epoxy substrate or a ceramic substrate.

[0013] A first resist layer 16 is laminated on the first main surface 61 of the substrate 3, and a second resist layer 17 is laminated on the surface of the second main surface 62 of the substrate 3. The first resist layer 16 prevents short circuits of electrodes and wirings arranged on the first base material layer 11, and the second resist layer 17 covers and protects the lower ends of the first interlayer connection conductor 55 and the second interlayer connection conductor 57, which will be described later. The first resist layer 16 and the second resist layer are, for example, insulating resin layers.

[0014] As shown in FIGS. 1 and 2, the coil element 5 is formed by winding a conductive wire 31 a plurality of times, and the coil element 5 functions as an antenna. The communication frequency band in the RFID module 1 of the embodiment is, for example, the UHF band from 860 MHz to 960 MHz. The number of turns and dimensions of the coil element 5 may be changed according to the communication characteristics.

[0015] The coil element 5 has a first densely wound portion 5a, a second densely wound portion 5b, and a sparsely wound portion 5c. The coil element 5 is an air-core coil having no cavity or magnetic core material along the winding axis. The first densely wound portion 5a is formed at both ends of the coil element 5, and the second densely wound portion 5b is formed, for example, at the center of the coil element 5 between the first densely wound portions 5a at both ends. The sparsely wound portion 5c is formed between the first densely wound portion 5a and the second densely wound portion 5b. Here, "densely wound" means that the winding pitch of the first densely wound portion 5a and the second densely wound portion 5b is narrower than that of the sparsely wound portion 5c. For example, the wire diameter and the winding pitch of the conductive wire 31 may be the same. In this case, in the first densely wound portion 5a and the second densely wound portion 5b, the conductive wires 31 are in contact with each other.

[0016] The total number of turns of the sparsely wound portion 5c is equal to or more than the total number of turns of the first densely wound portion 5a and the second densely wound portion 5b, for example, 2 times or more. In the first densely wound portion 5a, the number of turns of the conductive wire 31 is, for example, 2 turns or more.

[0017] Each first tightly wound portion 5a is connected to a first land 19 and a first electrode 27 disposed on the first main surface of the substrate 3 via solder 23. In this way, the first tightly wound portion 5a functions as a solder joint portion. The second tightly wound portion 5b functions as a portion to be adsorbed when adsorbed by a component mounter, but may be connected to an auxiliary electrode 29 disposed on the first main surface of the substrate 3 via solder 23. Thereby, when the resin layer 9 is molded, it is possible to prevent the coil element 5 from bending. The length of the second tightly wound portion 5b in the X-axis direction is larger than the aperture diameter of the adsorption nozzle of the component mounter.

[0018] Refer to FIG. 3. FIG. 3 is a cross-sectional view of the conductive wire 31 of the coil element 5. The conductive wire 31 of the coil element 5 is covered with an insulating film 33. Note that at the joint portion of the coil element 5 with the solder 23, the insulating film 33 is peeled off and the conductive wire 31 and the solder 23 are joined. The coil element 5 may be composed only of the conductive wire 31 not covered with the insulating film 33.

[0019] As shown in FIG. 1, the resin layer 9 seals the coil element 5 and the RFIC chip 7 and is laminated on the third main surface 11a of the first base layer 11 and the first resist layer 16. The resin layer 9 is formed of a general sealing resin such as an epoxy resin, for example.

[0020] Next, the substrate 3 will be described with reference to FIG. 4. FIG. 4 is a plan view showing the wiring electrodes on the substrate 3. FIG. 4(a) is a plan view showing the wiring electrodes on the first main surface 61 of the substrate 3. FIG. 4(b) is a perspective plan view of the substrate 3 seen through, showing the wiring electrodes on the second main surface 62. The dashed-dotted line in FIG. 4 indicates a through-hole connection.

[0021] As shown in FIG. 4(a), on the first main surface 61 which is the upper surface of the substrate 3, a first terminal 7a of the RFIC chip 7, a first tightly wound portion 5a on the side closer to the RFIC chip 7, and a first land 19 connected via the solder 23 are arranged, and a second land 21 connected to the second terminal 7b of the RFIC chip 7 via the solder 23 is arranged. On the first main surface 61 of the substrate 3, there are also arranged an auxiliary electrode 29 connected to the second tightly wound portion 5b via the solder 23, and a first electrode connected to the first tightly wound portion 5a on the side farther from the RFIC chip 7 via the solder 23.

[0022] A first interlayer connection conductor 55 and a second interlayer connection conductor 57 penetrating the inside of the substrate 3 are formed. The first interlayer connection conductor 55 is a conductive via connecting the second land 21 and the conductor pattern 53. The second interlayer connection conductor 57 is a conductive via connecting the first electrode 27 and the conductor pattern 53.

[0023] The first and second interlayer connection conductors 55 and 57 are, for example, conductors formed by solidifying (metallizing) a conductive paste filled in holes provided in the insulating substrate 3, but may also be plated through holes. The first and second interlayer connection conductors 55 and 57 are respectively arranged opposite to each other in the longitudinal direction of the third substrate.

[0024] On the second main surface 62 of the substrate 3, a conductor pattern 53 connecting the first interlayer connection conductor 55 and the second interlayer connection conductor 57 is arranged. The conductor pattern 53 has, for example, a linear shape extending in the longitudinal direction of the substrate 3. Since the conductor pattern 53 is not arranged outside the first and second interlayer connection conductors 55 and 57 in the longitudinal direction, when contact occurs between the RFID module and other articles during the manufacturing process or post-manufacturing handling, etc., the conductor pattern 53 can be prevented from being scraped.

[0025] The first land 19, the second land 21, the first electrode 27, the auxiliary electrode 29, and the conductor pattern 53 are all conductors, and are, for example, those obtained by patterning a copper foil by photolithography.

[0026] In the RFID module 1, an LC parallel resonance circuit is configured and is matched to radio waves of the communication frequency. Therefore, when the coil element 5 receives radio waves of the communication frequency, a current flows through the RFIC chip 7.

[0027] As shown in FIGS. 1 and 2, since the coil element 5 has the first tightly wound portions 5a at both ends, it can be soldered to the substrate 3, and the fixing strength of the coil element 5 can be increased. Further, the coil element 5 has a loosely wound portion 5c in a portion other than both ends where the conducting wire 31 is wound more sparsely than the first tightly wound portion 5a. Since the coupling coefficient Ka of the first tightly wound portion 5a and the second tightly wound portion 5b is larger than the coupling coefficient Kb of the loosely wound portion 5c, it becomes easier to release the magnetic field from the loosely wound portion 5c to the outside of the coil element 5 than from the first tightly wound portion 5a and the second tightly wound portion 5b. Thus, since a large amount of magnetic field is released from the loosely wound portion 5c, the performance of the coil element 5 as an antenna can be improved. Also, in the winding axis direction of the coil element 5, the ratio of the length of the loosely wound portion 5c is larger than the length of the first tightly wound portion 5a. Further, in the winding axis direction of the coil element 5, the ratio of the length of the loosely wound portion 5c is larger than the sum of the lengths of the first tightly wound portion 5a and the second tightly wound portion 5b. Thus, since the ratio of the length of the loosely wound portion 5c is large, more magnetic field can be released.

[0028] The current flowing through the metal plate 101 when the RFID module 1 is disposed on the metal plate 101 will be described with reference to FIGS. 5 and 6. FIG. 5 is a plan view for explaining the currents Ia and Ib flowing through the metal plate 101 when the RFID module 1 is placed on the metal plate 101. FIG. 6 is a longitudinal sectional view for explaining the current flowing through the metal plate 101 when the RFID module 1 is placed on the metal plate 101. In FIG. 5, the substrate 3 is omitted for easy understanding of the current flow.

[0029] When the metal plate 101 is used as a radiation element, the coil element 5 of the RFID module 1 couples with the magnetic field generated by the current flowing on the metal plate 101. The currents Ia and Ib flowing on the metal plate 101 flow in opposite directions with the center of the coil element 5 of the RFID module 1 as the boundary. Since the current density on the metal plate 101 is high at the ends of the metal plate 101, the magnetic field at the ends of the metal plate 101 becomes strong, and the magnetic field at the center of the metal plate 101 becomes weak. Even if there is a second closely wound portion 5b at the center of the coil element 5, it does not significantly affect the magnetic field coupling with the metal plate 101.

[0030] As described above, the RFID module 1 of the embodiment includes a substrate 3 having a first main surface 61 and a second main surface 62 facing each other, an RFIC chip 7 disposed on the first main surface 61 side of the substrate 3, and a coil element 5 around which a plurality of conductive wires 31 are wound. The first terminal 7a of the RFIC chip 7 is electrically connected to one end of the coil element 5, and the second terminal 7b of the RFIC chip 7 is electrically connected to the other end of the coil element 5. The coil element 5 has at least one loosely wound portion 5c, and both ends of the coil element 5 are first closely wound portions 5a in which the pitch between the conductive wires 31 is wound more narrowly than in the loosely wound portion 5c.

[0031] According to the RFID module 1 having this configuration, since the coil element 5 around which the conductive wires 31 are wound a plurality of times is adopted, the coil opening diameter can be increased more than when using a coil element body with legs, so that it can be miniaturized while maintaining the antenna characteristics. In addition, both ends of the coil element 5 are wound with a narrower pitch of the conductive wires 31 than the loosely wound portion 5c, and the loosely wound portion 5c is wound with a wider pitch of the conductive wires 31 than both ends. Therefore, in the portion wound loosely, the magnetic field is likely to be released to the outside of the coil element 5, so it functions as an antenna, and both ends wound tightly can increase the fixing strength as the connection portion of the substrate 3.

[0032] Also, in the winding axis direction of the coil element 5, the ratio of the length of the loosely wound portion 5c is larger than the length of the first closely wound portion 5a. Since the length of the loosely wound portion 5c is larger in ratio than the length of the first closely wound portion 5a, the antenna characteristics of the RFID module 1 can be improved.

[0033] Further, it has a second tightly wound portion 5b in which the pitch between the conducting wires 31 is wound more narrowly than in the loosely wound portion 5c. Since the coil element 5 has the second tightly wound portion 5b, the second tightly wound portion 5b can function as a portion to be adsorbed by the component mounter.

[0034] Also, the conducting wires 31 of the coil element 5 may be covered with an insulating film 33. In this case, since the inductance component of the coil element 5 can be increased, the length of the coil element 5 can be shortened, and the RFID module 1 can be miniaturized.

[0035] Also, the conducting wires 31 of the coil element 5 may not be covered with the insulating film 33. In this case, when mounting on the substrate 3 via solder, the process of peeling off the insulating film 33 at the joint portion can be omitted.

[0036] (Embodiment 2) Next, the RFID module 1A of Embodiment 2 will be described with reference to FIGS. 7 and 8. FIG. 7 is a longitudinal sectional view showing the outline of the RFID module 1A of Embodiment 2. FIG. 8 is a plan view showing each base material layer of the substrate 3A. FIG. 8(a) is a plan view showing the wiring electrodes on the first main surface 61 of the substrate 3A. FIG. 8(b) is a plan view showing the wiring electrodes on the fifth main surface of the second base material layer 13. FIG. 8(c) is a perspective plan view through the second base material layer 13, showing the wiring electrodes on the sixth main surface 13b. FIG. 8(d) is a perspective plan view through the third base material layer 15, showing the electrodes on the eighth main surface 15b. The dashed-dotted line in FIG. 8 indicates a through-hole connection.

[0037] The substrate 3A in Embodiment 2 is a laminated substrate, and the first land 19 extends toward the center in the longitudinal direction of the substrate 3 more than in Embodiment 1, and the substrate 3 is provided with a second electrode 47 that capacitively couples with the first land 19. Regarding the configuration other than this point and the points described below, the RFID module 1A of Embodiment 2 is the same as the RFID module 1 of Embodiment 1, and the description of the common configuration will be omitted.

[0038] The substrate 3A has a first base layer 11, a second base layer 13, and a third base layer 15. With the third base layer 15 as the bottom base layer, the second base layer 13 is laminated on the third base layer 15 toward the coil element 5, and the first base layer 11 is further laminated on the second base layer 13. The first base layer 11 to the third base layer 15 are each insulating, for example, a glass epoxy substrate, a ceramic substrate, or the like.

[0039] The third main surface 11a of the first base layer 11 corresponds to the first main surface 61 of the substrate 3. The fourth main surface 11b on the second main surface 62 side of the first base layer 11 is in contact with the fifth main surface 13a on the first main surface 61 side of the second base layer 13. The sixth main surface 13b on the second main surface 62 side of the second base layer 13 is in contact with the seventh main surface 15a on the first main surface 61 side of the third base layer 15. The eighth main surface 15b, which is the lower surface of the third base layer 15, faces the seventh main surface 15a and corresponds to the second main surface 62 of the substrate 3.

[0040] As shown in FIG. 8(b), a second electrode 47 is disposed below the first land 19 and the second land 21 on the fifth main surface 13a, which is the upper surface of the second base layer 13. The second electrode 47 faces the first land 19 and the second land 21, and a capacitance C1 is generated by the first land 19, the second land 21, and the second electrode 47.

[0041] As shown in FIGS. 7 and 8(c), a conductor pattern 53 is disposed on the sixth main surface 13b, which is the lower surface of the second base layer 13. FIG. 8(c) is a perspective view of the fifth main surface 13a from above.

[0042] In the substrate 3, a first interlayer connection conductor 55A and a second interlayer connection conductor 57A that penetrate the first base layer 11 and the second base layer 13, respectively, are formed. The first interlayer connection conductor 55 is a conductive via that connects from the first land 19 to the second electrode 47 and the conductor pattern 53. The second interlayer connection conductor 57 is a conductive via that connects the first electrode 27 and the conductor pattern 53.

[0043] The first and second interlayer connection conductors 55A and 57A are conductors formed by solidifying (metallizing) a conductive paste filled in holes provided in, for example, the insulating first base material layer 11 and the second base material layer 13, but may also be plated through holes. The first and second interlayer connection conductors 55A and 57A are respectively arranged to face each other in the longitudinal directions of the first base material layer 11 and the second base material layer 13.

[0044] The coil element 5 has an inductance L1, and the conductor pattern 53 has an inductance L2. The capacitance C1 is composed of the first land 19, the second land 21, the first base material layer 11, and the second electrode 47. The RFIC chip 7 has a resistor R and a capacitance C2 inside. The larger the capacitance C1, the larger the combined capacitance C and the smaller the resonance frequency f. When the resonance frequency with the communication frequency needs to be reduced, it can be achieved by increasing the area of the second electrode 47.

[0045] According to the RFID module 1A of Embodiment 2, the substrate 3A has a first base material layer 11 disposed on the first main surface 3a side and a second base material layer 13 disposed on the second main surface 3b side. The RFID module 1A includes a first land 19 disposed on the first main surface 3a side of the first base material layer 11 to which the first terminal 7a of the RFIC chip 7 is connected, a second land 21 disposed on the first main surface 3a side of the first base material layer 11 to which the second terminal 7b of the RFIC chip 7 is connected, a second electrode 47 facing the first land 19 and the second land 21 and disposed on the first main surface 3a side of the second base material layer 13, first and second interlayer connection conductors 55A and 57A respectively penetrating the first base material layer 11 and the second base material layer 13, and a conductor pattern 53 disposed on the second main surface 3b side of the second base material layer 13 for connecting the first interlayer connection conductor 55A and the second interlayer connection conductor 57A. The second land 21, the second electrode 47, and one end of the conductor pattern 53 are connected via the first interlayer connection conductor 55A. The other end of the conductor pattern 53 and the other end of the coil element 5 are connected via the second interlayer connection conductor 57A. The first land 19 and one end of the coil element 5 are connected.

[0046] Since the capacitor C1 composed of the first land 19, the second land 21, the first base layer 11, and the second electrode 47 is generated, the resonance frequency of the RFID module 1A can be reduced.

[0047] The present invention is not limited to the above-described embodiments and can be modified as follows.

[0048] In each of the above embodiments, the coil element 5 had the second closely wound portion 5b, but the present invention is not limited thereto. As shown in FIG. 9, a coil element 5D that does not have the second closely wound portion 5b may be used.

[0049] Although the present invention has been described in each embodiment with a certain degree of detail, the disclosed content of these embodiments should change in terms of the details of the configuration, and changes in the combination and order of elements in each embodiment can be realized without departing from the scope and spirit of the claimed invention.

[0050] (Summary of Embodiment) The RFID module according to the first aspect of the present invention includes a substrate having a first main surface and a second main surface facing each other, an RFIC chip disposed on the first main surface side of the substrate, and a coil element around which a plurality of turns of a conductive wire are wound. One end of the RFIC chip is electrically connected to one end of the coil element, and the other end of the RFIC chip is electrically connected to the other end of the coil element. The coil element has at least one loosely wound portion, and both ends of the coil element are first closely wound portions wound with a narrower pitch between conductive wires than the loosely wound portion.

[0051] In the RFID module of this aspect, since a coil element in which a conducting wire is wound multiple times is employed, the coil opening diameter can be made larger than when using a coil body with legs. As a result, the RFID module can be miniaturized while maintaining antenna characteristics. Both ends of the coil element are first tightly wound portions where the pitch between conducting wires is wound more narrowly than in the loosely wound portion. The loosely wound portion is wound with a wider pitch between conducting wires than the first tightly wound portion. Therefore, since the magnetic field is likely to be released to the outside of the coil element in the loosely wound portion, it functions as an antenna, and both ends, which are the first tightly wound portions, can increase the fixing strength as the connection portions of the substrate.

[0052] According to a second aspect, in the RFID module of the first aspect, in the winding axis direction of the coil element, the ratio of the length of the loosely wound portion is larger than the length of the first tightly wound portion. Since the ratio of the length of the loosely wound portion is larger than that of the first tightly wound portion in the coil element, the antenna characteristics of the RFID module can be improved.

[0053] According to a third aspect, in the RFID module of the first aspect, it has a second tightly wound portion where the pitch between conducting wires is wound more narrowly than in the loosely wound portion. As a result, the second tightly wound portion can function as a portion to be adsorbed by a component mounter.

[0054] According to a fourth aspect, in the RFID module of the third aspect, in the winding axis direction of the coil element, the ratio of the length of the loosely wound portion is larger than the sum of the lengths of the first tightly wound portion and the second tightly wound portion. Since the ratio of the length of the loosely wound portion is larger than the sum of the lengths of the first tightly wound portion and the second tightly wound portion in the coil element, the antenna characteristics of the RFID module can be improved.

[0055] According to a fifth aspect, in any one of the RFID modules of the first aspect to the fourth aspect, the conducting wire of the coil element is covered with an insulating film. As a result, the inductance component of the coil element can be increased, so the length of the coil element can be shortened, and the RFID module can be miniaturized.

[0056] According to the sixth aspect, in any one of the RFID modules of the first to fourth aspects, the conducting wire of the coil element is not covered with an insulating film. Thereby, when mounting on a substrate via solder, the process of peeling off the insulating film at the joint portion can be omitted.

[0057] According to the seventh aspect, in the RFID module of the third or fourth aspect, an auxiliary electrode disposed on the first main surface side of the substrate is provided, and the second tightly wound portion is connected to the auxiliary electrode via solder. Thereby, it is possible to prevent the coil element from bending.

[0058] According to the eighth aspect, in any one of the RFID modules of the first to seventh aspects, the substrate has a first base material layer disposed on the first main surface side and a second base material layer disposed on the second main surface side. The RFID module includes a first land disposed on the first main surface side of the first base material layer to which one end of the RFIC chip is connected, a second land disposed on the first main surface side of the first base material layer to which the other end of the RFIC chip is connected, a second electrode facing the first land and the second land and disposed on the first main surface side of the second base material layer, first and second interlayer connection conductors penetrating the first base material layer and the second base material layer respectively, and a conductor pattern disposed on the second main surface side of the second base material layer for connecting the first interlayer connection conductor and the second interlayer connection conductor. The second land, the second electrode, and one end of the conductor pattern are connected via the first interlayer connection conductor. The other end of the conductor pattern and the other end of the coil element are connected via the second interlayer connection conductor, and the first land and one end of the coil element are connected. Since capacitance is generated between the first land and the second land and the second electrode, the resonance frequency of the RFID module can be lowered.

[0059] According to the ninth aspect, in the RFID module of the eighth aspect, the substrate further includes a third base material layer on which the second main surface side of the second base material layer is laminated. The third base material layer can protect the conductor pattern disposed on the second main surface side of the second base material layer.

Description of Reference Numerals

[0060] 1. 1A RFID module 3. 3A substrate 5 Coil element 5a First tightly wound part 5b Second tightly wound part 5c Loosely wound part 7 RFIC chip 7a First terminal 7b Second terminal 9 Resin layer 11 First base material layer 11a Third main surface 11b Fourth main surface 13 Second base material layer 13a Fifth main surface 13b Sixth main surface 15 Third base material layer 15a Seventh main surface 15b Eighth main surface 16 First resist layer 17 Second resist layer 19 First land 21 Second land 23 Solder 27 First electrode 29 Auxiliary electrode 31 Conductive wire 33 Insulating film 47 Second electrode 53 Conductor pattern 55 First interlayer connection conductor 57 Second interlayer connection conductor 61 First main surface 62 Second main surface 101 Metal plate Ia, Ib Current

Claims

1. A substrate having a first main surface and a second main surface facing each other, an RFIC chip disposed on the first main surface side of the substrate, and a coil element around which a plurality of turns of a conductor are wound, one end of the RFIC chip is electrically connected to one end of the coil element, the other end of the RFIC chip is electrically connected to the other end of the coil element, the coil element has at least one sparse winding portion, both ends of the coil element are first tightly wound portions wound with a narrower conductor pitch than that of the sparse winding portion, an RFID module.

2. In the winding axis direction of the coil element, the ratio of the length of the sparse winding portion is larger than the length of the first tightly wound portion, the RFID module according to claim 1.

3. having a second tightly wound portion wound with a narrower conductor pitch than that of the sparse winding portion, the RFID module according to claim 1.

4. In the winding axis direction of the coil element, the ratio of the length of the sparse winding portion is larger than the sum of the lengths of the first tightly wound portion and the second tightly wound portion, the RFID module according to claim 3.

5. the conductor of the coil element is covered with an insulating film, the RFID module according to claim 1.

6. the conductor of the coil element is not covered with an insulating film, the RFID module according to claim 1.

7. including an auxiliary electrode disposed on the first main surface side of the substrate, the second tightly wound portion is connected to the auxiliary electrode via solder, the RFID module according to claim 3.

8. the substrate has a first base material layer disposed on the first main surface side and a second base material layer disposed on the second main surface side, the RFID module a first land disposed on the first main surface side of the first base material layer and connected to one end of the RFIC chip, a second land disposed on the first main surface side of the first base material layer and connected to the other end of the RFIC chip, a second electrode disposed on the first main surface side of the second base material layer and facing the first land and the second land, first and second interlayer connection conductors penetrating the first base material layer and the second base material layer respectively, a conductor pattern disposed on the second main surface side of the second base material layer and connecting the first interlayer connection conductor and the second interlayer connection conductor, the second land, the second electrode, and one end of the conductor pattern are connected via the first interlayer connection conductor, The other end of the conductor pattern and the other end of the coil element are connected via the second interlayer connection conductor, The first land and one end of the coil element are connected, The RFID module according to any one of claims 1 to 7.

9. The substrate further includes a third base material layer on which the second main surface side of the second base material layer is laminated, The RFID module according to claim 8.

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