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

RFID module

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

[0002] Conventionally, products are managed by attaching an RFID (Radio-Frequency Identification) module, which is a wireless communication device, to the product. One form of RFID module is one in which a coil conductor functioning as an antenna is disposed on an insulating substrate together with an RFIC (Radio-Frequency Integrated Circuit) chip.

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

[0004] International Publication No. 2018-235714

[0005] The coil conductor in the RFID module disclosed in Patent Document 1 has legs for mounting, so the diameter of the coil opening is reduced by the amount of mounting space. In order to ensure antenna characteristics, the RFID module becomes larger.

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

[0007] An RFID module according to one aspect of the present invention includes a substrate having a first principal surface and a second principal surface facing each other, an RFIC chip disposed on the first principal surface of the substrate, and a coil element formed by winding a conductor multiple 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 loosely wound portion, and both ends of the coil element are first densely wound portions in which the conductor is wound at a narrower pitch than the loosely wound portion.

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

[0009] A longitudinal sectional view showing an outline of an RFID module of embodiment 1. A perspective view of a coil element. A cross-sectional view of a conductor of a coil element. A plan view showing wiring electrodes on a substrate of embodiment 1. A plan view explaining the current flowing through a metal plate when the RFID module is placed on the metal plate. A longitudinal sectional view explaining the current flowing through a metal plate when the RFID module is placed on the metal plate. A longitudinal sectional view showing an outline of an RFID module of embodiment 2. A plan view showing each base layer of a laminated substrate. A longitudinal sectional view showing an outline of an RFID module in a modified example.

[0010] Each of the embodiments described below shows a specific example of the present invention, and the present invention is not limited to this configuration. Furthermore, the numerical values, shapes, configurations, steps, and step orders specifically shown in the following embodiments are examples and do not limit the present invention. Among the components in the following embodiments, components that are not described in the independent claims that represent the highest concepts are described as optional components. Furthermore, in all embodiments, the configurations in each modification are the same, and the configurations described in each modification may be combined with each other.

[0011] (Embodiment 1) Next, a schematic configuration of an RFID module 1 according to embodiment 1 of the present invention will be described. FIG. 1 is a longitudinal cross-sectional view of the RFID module 1 according to embodiment 1. FIG. 2 is a perspective view of a coil element. In the figures, the X-Y-Z coordinate system is used to facilitate 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 one another. Furthermore, in the description of the embodiment, the positive direction of the Z axis is the upward direction, and the negative direction of the Z axis is the downward direction.

[0012] The RFID module 1 of the embodiment includes a substrate 3, a coil element 5 and an RFIC chip 7 arranged on a 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 the first embodiment is a double-sided substrate, and a 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 second main surface 62 of the substrate 3. The first resist layer 16 prevents short-circuiting of electrodes and wiring arranged on the first base material layer 11, and the second resist layer 17 covers and protects the lower ends of first interlayer connection conductors 55 and second interlayer connection conductors 57, which will be described later. The first resist layer 16 and the second resist layer are, for example, insulating resin layers.

[0014] 1 and 2 , the coil element 5 is configured by winding a conductor 31 multiple times, and the coil element 5 functions as an antenna. The communication frequency band in the RFID module 1 of this embodiment is, for example, the UHF band of 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 loosely wound portion 5c. The coil element 5 is an air-core coil that does not have a 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 between the first densely wound portions 5a at both ends, for example, in the center of the coil element 5. The loosely 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 conductor 31 is narrower in the first densely wound portion 5a and the second densely wound portion 5b than in the loosely wound portion 5c. For example, the wire diameter and winding pitch of the conductor 31 may be the same. In this case, the conductor 31 contacts each other in the first densely wound portion 5a and the second densely wound portion 5b.

[0016] The total number of turns of the loosely wound portion 5c is equal to or greater than the total number of turns of the first densely wound portion 5a and the second densely wound portion 5b, for example, equal to or greater than twice the total number of turns of the wire 31. In the first densely wound portion 5a, the number of turns of the wire 31 is equal to or greater than two.

[0017] Each first dense winding portion 5a is connected via solder 23 to a first land 19 and a first electrode 27 arranged on the first main surface of the substrate 3. In this way, the first dense winding portion 5a functions as a solder joint. The second dense winding portion 5b functions as a part to be suctioned when the component is suctioned by a component mounter, and may also be connected via solder 23 to an auxiliary electrode 29 arranged on the first main surface of the substrate 3. This makes it possible to prevent the coil element 5 from bending when the resin layer 9 is molded. The length in the X-axis direction of the second dense winding portion 5b is greater than the diameter of the suction nozzle of the component mounter.

[0018] Please refer to Figure 3. Figure 3 is a cross-sectional view of the conductor 31 of the coil element 5. The conductor 31 of the coil element 5 is covered with an insulating film 33. At the joint portion of the coil element 5 with the solder 23, the insulating film 33 is removed and the conductor 31 and the solder 23 are joined. The coil element 5 may be composed of only the conductor 31 that is not covered with the insulating film 33.

[0019] 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 material layer 11 and the first resist layer 16. The resin layer 9 is formed of a general sealing resin such as an epoxy resin.

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

[0021] 4(a), a first land 19 connected via solder 23 to a first terminal 7a of the RFIC chip 7 and the first dense winding portion 5a closer to the RFIC chip 7, and a second land 21 connected via solder 23 to a second terminal 7b of the RFIC chip 7 are arranged on a first main surface 61, which is the top surface of the substrate 3. Also arranged on the first main surface 61 of the substrate 3 are an auxiliary electrode 29 connected via solder 23 to the second dense winding portion 5b, and a first electrode connected via solder 23 to the first dense winding portion 5a farther from the RFIC chip 7.

[0022] A first interlayer connection conductor 55 and a second interlayer connection conductor 57 are formed to penetrate the inside of the substrate 3. The first interlayer connection conductor 55 is a conductive via that connects the second land 21 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.

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

[0024] Conductor pattern 53 connecting first interlayer connection conductor 55 and second interlayer connection conductor 57 is arranged on second main surface 62 of substrate 3. Conductor pattern 53 has, for example, a linear shape extending in the longitudinal direction of substrate 3. Since conductor pattern 53 is not arranged outside first and second interlayer connection conductors 55, 57 in the longitudinal direction, it is possible to prevent conductor pattern 53 from being scraped off when contact between the RFID module and other articles occurs during the manufacturing process or handling after manufacturing.

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

[0026] An LC parallel resonant circuit is configured within the RFID module 1 and is matched to radio waves of the communication frequency, so that 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 , the coil element 5 has first dense winding portions 5a at both ends, allowing it to be soldered to the substrate 3, thereby increasing the bonding strength of the coil element 5. The coil element 5 also has loosely wound portions 5c in which the conductor wire 31 is wound more loosely than the first dense winding portion 5a at locations other than the ends. The coupling coefficient Ka between the first dense winding portion 5a and the second dense winding portion 5b is greater than the coupling coefficient Kb between the loosely wound portion 5c. This makes it easier for the loosely wound portion 5c to emit a magnetic field to the outside of the coil element 5 than the first dense winding portion 5a and the second dense winding portion 5b. Because a larger magnetic field is emitted from the loosely wound portion 5c, the performance of the coil element 5 as an antenna can be improved. Furthermore, in the winding axis direction of the coil element 5, the length of the loosely wound portion 5c is greater than the length of the first dense winding portion 5a. Furthermore, in the winding axis direction of the coil element 5, the length of the loosely wound portion 5c is greater than the sum of the lengths of the first dense winding portion 5a and the second dense winding portion 5b. In this way, since the proportion of the length of the open winding portion 5c is large, a larger magnetic field can be emitted.

[0028] The current flowing through the metal plate 101 when the RFID module 1 is placed on the metal plate 101 will be described with reference to Fig. 5 and Fig. 6. Fig. 5 is a plan view illustrating 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 vertical cross-sectional view illustrating the current flowing through the metal plate 101 when the RFID module 1 is placed on the metal plate 101. Note that the substrate 3 is omitted from Fig. 5 to make it easier to understand the current flow.

[0029] When the metal plate 101 is used as a radiating 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. Because the current density on the metal plate 101 is higher at the ends of the metal plate 101, the magnetic field at the ends of the metal plate 101 is stronger and the magnetic field at the center of the metal plate 101 is weaker. Even if the second dense winding portion 5b is present in 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 the substrate 3 having the first main surface 61 and the second main surface 62 facing each other, the RFIC chip 7 disposed on the first main surface 61 side of the substrate 3, and the coil element 5 having the conductor wire 31 wound thereon multiple times. 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 densely wound portions 5a in which the conductor wire 31 is wound at a narrower pitch than in the loosely wound portion 5c.

[0031] The RFID module 1 having this configuration employs a coil element 5 in which the conductor wire 31 is wound multiple times, allowing for a larger coil opening diameter than when a coil element with legs is used, thereby enabling miniaturization while maintaining antenna characteristics. Furthermore, the conductor wire 31 is wound at a narrower pitch at both ends of the coil element 5 than at the sparsely wound portions 5c, and the conductor wire 31 is wound at a wider pitch at the sparsely wound portions 5c than at both ends. Therefore, the sparsely wound portions function as an antenna because the magnetic field is easily released to the outside of the coil element 5, while the densely wound ends function as connection portions for the substrate 3, increasing the bonding strength.

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

[0033] The coil element 5 also has a second densely wound portion 5b in which the pitch between the conductor wires 31 is narrower than that of the loosely wound portion 5c. By having the second densely wound portion 5b in the coil element 5, the second densely wound portion 5b can function as a portion to be attracted to a component mounter.

[0034] Furthermore, the conductor 31 of the coil element 5 may be covered with an insulating film 33. In this case, the inductance component of the coil element 5 can be increased, so that the length of the coil element 5 can be shortened, and the RFID module 1 can be made smaller.

[0035] Furthermore, the conductor 31 of the coil element 5 does not have to be covered with the insulating film 33. In this case, when mounting the coil element 5 on the substrate 3 via solder, the step of peeling off the insulating film 33 at the joining portion can be omitted.

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

[0037] The substrate 3A in the second embodiment is a laminated substrate, in which the first lands 19 extend further toward the center in the longitudinal direction of the substrate 3 than in the first embodiment, and a second electrode 47 that is capacitively coupled to the first lands 19 is provided within the substrate 3. Other than this point and points described below, the configuration of the RFID module 1A in the second embodiment is the same as that of the RFID module 1 in the first embodiment, and therefore a description of the common configuration will be omitted.

[0038] The substrate 3A has a first substrate layer 11, a second substrate layer 13, and a third substrate layer 15, with the third substrate layer 15 serving as the bottom substrate, the second substrate layer 13 being stacked on the third substrate layer 15 facing the coil element 5, and the first substrate layer 11 being further stacked on the second substrate layer 13. The first substrate layer 11 to the third substrate layer 15 are each insulating, and are, for example, a glass epoxy substrate or a ceramic substrate.

[0039] The third main surface 11a of the first base layer 11 corresponds to the first main surface 61 of the substrate 3. A fourth main surface 11b on the second main surface 62 side of the first base layer 11 is in contact with a fifth main surface 13a on the first main surface 61 side of the second base layer 13. A sixth main surface 13b on the second main surface 62 side of the second base layer 13 is in contact with a seventh main surface 15a on the first main surface 61 side of the third base layer 15. An 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] 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 between the first land 19, the second land 21, and the second electrode 47.

[0041] 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 see-through view of the fifth main surface 13a from above.

[0042] The substrate 3 is formed with a first interlayer connection conductor 55A and a second interlayer connection conductor 57A that respectively penetrate the first base material layer 11 and the second base material layer 13. The first interlayer connection conductor 55 is a conductive via that connects 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, for example, conductors formed by solidifying (metallizing) a conductive paste filled in holes provided in the insulating first base layer 11 and second base layer 13, but may also be plated through holes. The first and second interlayer connection conductors 55A and 57A are arranged opposite each other in the longitudinal direction of the first base layer 11 and second base layer 13, respectively.

[0044] The coil element 5 has an inductance L1, and the conductor pattern 53 has an inductance L2. The capacitance C1 is formed by the first land 19, the second land 21, the first base material layer 11, and the second electrode 47. The RFIC chip 7 also has an internal resistance R and capacitance C2. The larger the capacitance C1, the larger the combined capacitance C becomes, and the smaller the resonant frequency f becomes. If the resonant frequency with the communication frequency needs to be reduced, this can be achieved by increasing the area of ​​the second electrode 47.

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

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

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

[0048] In each of the above-described embodiments, the coil element 5 has the second densely wound portion 5b, but this is not limiting. As shown in Fig. 9, a coil element 5D may be used that does not have the second densely wound portion 5b.

[0049] Although the present invention has been described in various embodiments with a certain degree of detail, the disclosure of these embodiments may vary in structural details, and variations in the combination and order of elements in the various embodiments may be realized without departing from the scope and spirit of the invention as claimed.

[0050] (Summary of the Embodiments) An RFID module according to a 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 of the substrate, and a coil element formed by winding a conductor multiple 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 loosely wound portion, and both ends of the coil element are first densely wound portions in which the conductor is wound at a narrower pitch than the loosely wound portion.

[0051] In this RFID module, a coil element in which the conductor wire is wound multiple times is used, allowing for a larger coil opening diameter than when a coil element with legs is used. This allows for a smaller RFID module while maintaining antenna characteristics. Both ends of the coil element are first densely wound sections in which the conductor wires are wound at a narrower pitch than the openly wound section. The openly wound section is wound with a wider pitch than the first densely wound section. Therefore, the openly wound section functions as an antenna because the magnetic field is easily released to the outside of the coil element, and both ends, which are first densely wound sections, can increase the bonding strength as connection parts for the substrate.

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

[0053] According to a third aspect, the RFID module of the first aspect has a second densely wound portion in which the conductors are wound at a narrower pitch than the openly wound portion, thereby allowing the second densely wound portion to function as a portion to be attracted to a component mounter.

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

[0055] According to a fifth aspect, in the RFID module of any one of the first to fourth aspects, the conductor of the coil element is covered with an insulating film, which increases the inductance component of the coil element, thereby shortening the length of the coil element and enabling the RFID module to be miniaturized.

[0056] According to a sixth aspect, in the RFID module of any one of the first to fourth aspects, the conductor of the coil element is not covered with an insulating film, which makes it possible to omit the step of peeling off the insulating film at the joint when the RFID module is attached to the board via solder.

[0057] According to a seventh aspect, in the RFID module of the third or fourth aspect, an auxiliary electrode is provided on the first main surface of the substrate, and the second dense winding portion is connected to the auxiliary electrode via solder, thereby preventing the coil element from sagging.

[0058] According to an eighth aspect, in the RFID module of any one of the first to seventh aspects, the substrate has a first base material layer disposed on the first principal surface side and a second base material layer disposed on the second principal surface side. The RFID module includes: a first land disposed on the first principal surface side of the first base material layer and connected to one end of the RFIC chip; a second land disposed on the first principal 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 principal surface side of the second base material layer facing the first and second lands; first and second interlayer connection conductors penetrating the first and second base material layers, respectively; and a conductor pattern disposed on the second principal 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 a second interlayer connecting conductor, and the first land and one end of the coil element are connected. Capacitance is generated between the first land and the second electrode and between the second land and the second electrode, thereby lowering the resonance frequency of the RFID module.

[0059] According to a 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, and the third base material layer can protect the conductor pattern arranged on the second main surface side of the second base material layer.

[0060] REFERENCE SIGNS LIST 1, 1A RFID module 3, 3A Substrate 5 Coil element 5a First densely wound portion 5b Second densely wound portion 5c Openly wound portion 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 Conductive 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 opposed to each other; An RFIC chip disposed on the first main surface side of the substrate; A coil element having a conductive wire wound multiple 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 open winding portion, Both ends of the coil element are first densely wound portions in which the conductor pitch is narrower than that of the openly wound portion. RFID module.

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

3. a second densely wound portion in which the conductor wires are wound at a narrower pitch than the openly wound portion; The RFID module according to claim 1 .

4. a ratio of a length of the loosely wound portion to a sum of a length of the first densely wound portion and a length of the second densely wound portion in a winding axial direction of the coil element is larger than a ratio of a length of the loosely wound portion to a sum of a length of the first densely wound portion and a length of the second densely 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. an auxiliary electrode disposed on a first main surface side of the substrate; The second dense winding 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 includes: a first land disposed on a first main surface side of the first base layer and connected to one end of the RFIC chip; a second land disposed on the first main surface side of the first base layer and connected to the other end of the RFIC chip; a second electrode disposed on a first main surface side of the second base layer, the second electrode 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 a second main surface side of the second base 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 to each other.

8. An RFID module according to claim 1.

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.