RFID module

Abstract

This RFID module has the following features: a substrate with a first main surface and a second main surface facing each other; an RFIC chip located on the side of the first main surface of the substrate; and a coil element on which a conductive wire is 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 sparsely wound section. Both ends of the coil element are densely wound sections where the spacing between the conductive wires is narrower than in the sparsely wound section.

Description

Technical area

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

[0002] Traditionally, a product was managed by attaching a radio-frequency identification (RFID) module, a wireless communication device, to the product. One form of RFID module is one in which a coil conductor, acting as an antenna, is mounted on an insulating substrate, along with a radio-frequency integrated circuit (RFIC) chip.

[0003] For example, Patent Document 1 proposes an RFID module including a coil conductor in which coil elements with legs for fixing are arranged in a row. State of the art documentPatent document

[0004] Patent document 1: WO2018 / 235714 Brief description of the inventionTechnical problem

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

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

[0007] An RFID module according to one aspect of the present invention comprises: a substrate having a first main surface and a second main surface facing each other; an RFIC chip disposed on one side of the first main surface of the substrate; and a coil element having a conductor wound multiple times. One end of the RFIC chip is electrically connected to one end of the coil element, while 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, wherein both ends of the coil element are first densely wound portions in which the conductor is wound at a narrower pitch than in the sparsely wound portion. Advantageous effect of the invention

[0008] According to the present invention, an RFID module can be provided that can be downsized while maintaining the antenna characteristics. Short description of the drawings Fig. 1 is a longitudinal sectional view showing a schematic of an RFID module according to a first embodiment. Fig. 2 is a perspective view of a coil element. Fig. 3 is a cross-sectional view of a conductor of the coil element. Fig. 4 is a plan view showing wiring electrodes on a substrate of the first embodiment. Fig. 5 is a plan view illustrating current flowing through a metal plate when the RFID module is placed on the metal plate. Fig. 6 is a longitudinal sectional view illustrating current flowing through the metal plate when the RFID module is placed on the metal plate. Fig. 7 is a longitudinal sectional view showing a schematic of an RFID module according to a second embodiment. Fig. 8 is a plan view showing each base material layer of the laminated substrate. Fig. 9 is a longitudinal sectional view showing a scheme of an RFID module according to a variant. Description of the embodiments

[0009] Embodiments described below show a specific example of the present invention, and the present invention is not limited to these configurations. Furthermore, the numerical values, shapes, configurations, steps, and order of steps specifically shown in the following embodiments show examples and do not limit the present invention. Of the components in the following embodiments, those not described in an independent claim showing the highest concept are described as optional components. Furthermore, in all the embodiments, configurations in their respective variants are also similar, and the configuration described in each variant can be combined with another. First embodiment

[0010] A schematic configuration of an RFID module 1 according to a first embodiment of the present invention will be described below. Fig. 1 is a longitudinal sectional view of the RFID module 1 of the first embodiment. Fig. Figure 2 is a perspective view of a coil element. In the figures, the XYZ 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 orthogonal to each other. In the embodiment, the positive direction of the Z-axis is described as the upward direction, while the negative direction of the Z-axis is described as the downward direction.

[0011] 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 with a second main surface 62, which is the lower surface of the substrate 3, and the first main surface 61 facing each other. The substrate 3 has insulating properties and is, for example, a glass epoxy substrate or a ceramic substrate.

[0012] 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 a first base material layer 11, and the second resist layer 17 covers and protects the lower ends of a first interlayer connection conductor 55 and a second interlayer connection conductor 57, which will be described below. The first resist layer and the second resist layer are, for example, insulating resin layers.

[0013] As it is in Fig. 1 and Fig. As shown in Figure 2, the coil element 5 is configured by winding a conductive wire 31 multiple 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, a UHF band of 860 MHz to 960 MHz. The number of turns and dimensions of the coil element 5 can be changed depending on the communication characteristics.

[0014] 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 that has 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 between the first densely wound portion 5a at both ends, for example, in the center of the coil element 5. 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 conductive wire 31 in the first densely wound portion 5a and the second densely wound portion 5b is narrower than in the sparsely wound portion 5c. For example, the wire diameter and the winding length of the conductive wire 31 may be the same. In this case, the conductive wire 31 in the first densely wound portion 5a and the second densely wound portion 5b is in contact with each other.

[0015] The total number of turns of the sparsely 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, and is, for example, equal to or greater than twice. In the first densely wound portion 5a, the number of turns of the conductive wire 31 is, for example, equal to or greater than two.

[0016] The respective first densely wound portions 5a are connected via solder 23 to a first land 19 and a first electrode 27, respectively, which are arranged on the first main surface of the substrate 3. In this way, the first densely wound portions 5a function as solder connection portions. The second densely wound portion 5b functions as a portion that is sucked when the substrate is sucked by a component mounting device and can be connected via the 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 of the second densely wound portion 5b in the X-axis direction is larger than the hole diameter of the suction nozzle of the component mounting device.

[0017] It will be Fig. 3 referred to. 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 connecting portions of the coil element 5 to the solder 23, the insulating film 33 is removed, so that the conductive wire 31 and the solder 23 are connected. The coil element 5 may be configured with only the conductive wire 31, which is not covered with the insulating film 33.

[0018] As it is in Fig. As shown in Figure 1, the resin layer 9 seals the coil element 5 and the RFIC chip 7 and is laminated on a third main surface 11a of the first base material layer 11 and on the first resist layer 16. The resin layer 9 is formed, for example, from a general sealing resin such as an epoxy resin.

[0019] With reference to Fig. 4 describes the substrate 3. Fig. 4 is a plan view showing 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. Fig. 4(b) is a see-through plan view of the substrate 3 showing wiring electrodes on the second main surface 62. The dashed lines in Fig. 4 indicate through-hole connections.

[0020] As it is in Fig. As shown in Fig. 4(a), on the first main surface 61, which is the upper surface of the substrate 3, there are disposed the first land 19 connected via the solder 23 to the first terminal 7a of the RFIC chip 7 and the first densely wound portion 5a on the side closer to the RFIC chip 7, and a second land 21 connected via the solder 23 to the second terminal 7b of the RFIC chip 7. Also disposed on the first main surface 61 of the substrate 3 are the auxiliary electrode 29 connected via the solder 23 to the second densely wound portion 5b, and the first electrode connected via the solder 23 to the first densely wound portion 5a on the side farther from the RFIC chip 7.

[0021] The first interlayer connection conductor 55 and the second interlayer connection conductor 57 are formed to extend through the interior of the substrate 3. The first interlayer connection conductor 55 is a conductive through-hole connecting the second ridge 21 and a conductor pattern 53. The second interlayer connection conductor 57 is a conductive through-hole connecting the first electrode 27 and the conductor pattern 53.

[0022] The first and second interlayer connection conductors 55 and 57 are, for example, conductors formed by solidifying (metallizing) 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 and 57 are arranged facing each other in the respective longitudinal directions of the substrate 3.

[0023] The conductor pattern 53 connecting the first interlayer connection conductor 55 and the second interlayer connection conductor 57 is arranged on the second main surface 62 of the substrate 3. The conductor pattern 53 has, for example, a rectilinear 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, the conductor pattern 53 can be prevented from being scraped off, for example, when the RFID module comes into contact with other articles during the manufacturing process, post-manufacturing handling, etc.

[0024] The first web 19, the second web 21, the first electrode 27, the auxiliary electrode 29 and the conductor structure 53 are each a conductor and are formed by structuring copper foil, for example by photolithography.

[0025] An LC parallel resonance circuit is configured in the RFID module 1 and is adapted to radio waves of a communication frequency, so that when the coil element 5 receives radio waves of the communication frequency, a current flows through the RFIC chip 7.

[0026] As it is in Fig. 1 and Fig. As shown in Fig. 2, the coil element 5 has the first densely wound portion 5a at both ends and can therefore be soldered to the substrate 3, with the result that the fixing strength of the coil element 5 can be increased. The coil element 5 also has the sparsely wound portion 5c, in which the conductive wire 31 is wound more sparsely than the first densely wound portion 5a, at locations other than both ends. Since the coupling coefficient Ka of the first densely wound portion 5a and the second densely wound portion 5b is larger than the coupling coefficient Kb of the sparsely wound portion 5c, the magnetic field is more easily emitted from the sparsely wound portion 5c to the outside of the coil element 5 than from the first densely wound portion 5a and the second densely wound portion 5b.In this way, since a large amount of magnetic field is emitted from the sparsely 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 sparsely wound portion 5c is proportionally larger than the length of the first densely wound portion 5a. Furthermore, in the winding axis direction of the coil element 5, the length of the sparsely wound portion 5c is proportionally larger than the sum of the length of the first densely wound portion 5a and the length of the second densely wound portion 5b. Since the proportion of the length of the sparsely wound portion 5c is large, a larger amount of magnetic field can be emitted in this way.

[0027] Current flowing through a metal plate 101 when the RFID module 1 is arranged on the metal plate 101 is described with reference to Fig. 5 and Fig. 6 described. Fig. 5 is a plan view explaining currents Ia and Ib flowing through the metal plate 101 when the RFID module 1 is placed on the metal plate 101. Fig. Fig. 6 is a longitudinal sectional view explaining the current flowing through the metal plate 101 when the RFID module 1 is placed on the metal plate 101. It should be noted that the substrate 3 in Fig. 5 is omitted to make it easier to understand the current flow.

[0028] When the metal plate 101 is used as a radiating element, the coil element 5 of the RFID module 1 couples with a magnetic field generated by 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 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 tightly wound 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.

[0029] 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 in which the conductive wire 31 is wound 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 sparsely wound portion 5c, and both ends of the coil element 5 are the first densely wound portions 5a in which the conductive wire 31 is wound at a narrower pitch than in the sparsely wound portion 5c.

[0030] According to the RFID module 1 having this configuration, by using the coil element 5 in which the conductive wire 31 is wound multiple times, the coil opening diameter can be made larger than when using a coil element with legs, and thus the size can be reduced while maintaining the antenna characteristics. The conductive wire 31 is wound at a narrower portion at both ends of the coil element 5 than at the sparsely wound portion 5c, and the conductive wire 31 is wound at a wider pitch in the sparsely wound portion 5c than at both ends. Thus, the sparsely wound portion functions as an antenna because the magnetic field is easily released to the outside of the coil element 5, and the densely wound ends can increase the fixing strength as connecting portions for the substrate 3.

[0031] The length of the sparsely wound portion 5c is proportionally larger 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 sparsely wound portion 5c is proportionally larger than the length of the first densely wound portion 5a, the antenna characteristics of the RFID module 1 can be improved.

[0032] The coil element 5 has the second densely wound portion 5b, in which the distance between the conductor wires 31 is narrower than that of the sparsely wound portion 5c. By having the second densely wound portion 5b, the second densely wound portion 5b can function as a suction portion that is suctioned by a component fixing device.

[0033] The conductive wire 31 of the coil element 5 can be covered with the 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.

[0034] The conductive wire 31 of the coil element 5 does not need to be covered with the insulating film 33. In this case, when the coil element 5 is fixed to the substrate 3 by soldering, the process of peeling off the insulating film 33 at the connecting portions can be omitted. (Second embodiment)

[0035] With reference to Fig. 7 and Fig. 8, an RFID module 1A of a second embodiment is described. Fig. 7 is a longitudinal sectional view showing a schematic of the RFID module 1A of the second embodiment. Fig. 8 is a plan view showing each base material layer of a substrate 3A. Fig. Fig. 8(a) is a plan view showing wiring electrodes on the 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 see-through plan view of the second base material layer 13 showing wiring electrodes on a sixth main surface 13b. Fig. Figure 8(d) is a see-through plan view through a third base material layer 15 showing electrodes on an eighth major surface 15b. The dashed lines in Fig. 8 indicate through-hole connections.

[0036] The substrate 3A in the second embodiment is a laminated substrate in which the first ridge 19 extends further toward the center in the longitudinal direction of the substrate 3 than in the first embodiment, and includes, in the substrate 3, a second electrode 47 capacitively coupled to the first ridge 19. Except for this point and the 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 thus, the description of the general configuration is omitted.

[0037] The substrate 3A includes the first substrate layer 11, the second substrate layer 13, and the third substrate layer 15. The third substrate layer 15 serves as a bottom substrate, the second substrate layer 13 is laminated on the third substrate layer 15 toward the coil element 5, and the first substrate layer 11 is further laminated 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.

[0038] A third main surface 11a of the first base material 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 material layer 11 is in contact with a fifth main surface 13a on the first main surface 61 side of the second base material layer 13. The sixth main surface 13b on the second main surface 62 side of the second base material layer 13 is in contact with a seventh main surface 15a on the first main surface 61 side of the third base material layer 15. An eighth main surface 15b, which is the lower surface of the third base material layer 15, faces the seventh main surface 15a and corresponds to the second main surface 62 of the substrate 3.

[0039] As it is in Fig. As shown in Fig. 8(b), the second electrode 47 is disposed below the first ridge 19 and the second ridge 21 on the fifth main surface 13a, which is the upper surface of the second base material layer 13. The second electrode 47 faces the first ridge 19 and the second ridge 21, and a capacitance C1 is generated between the first ridge 19 and the second electrode 47 and between the second ridge 21 and the second electrode 47.

[0040] As it is in Fig. 7 and Fig. As shown in Fig. 8(c), the conductor pattern 53 is arranged on the sixth main surface 13b, which is the lower surface of the second base material layer 13. Fig. 8(c) is a top view of the fifth principal surface 13a.

[0041] A first interlayer connection conductor 55A and a second interlayer connection conductor 57A are formed in the substrate 3, each extending through the first base material layer 11 and the second base material layer 13. The first interlayer connection conductor 55 is a conductive via that provides a connection from the first ridge 19 through the second electrode 47 to the conductor pattern 53. The second interlayer connection conductor 57 is a conductive via that provides a connection between the first electrode 27 and the conductor pattern 53.

[0042] The first and second interlayer connection conductors 55A and 57A are, for example, conductors formed by solidifying (metallizing) conductive paste filled in holes formed in the insulating first base material layer 11 and the second base material layer 13, but they may also be plated through holes. The first and second interlayer connection conductors 55A and 57A are arranged to face each other in the longitudinal direction of the first base material layer 11 and the second base material layer 13.

[0043] The coil element 5 has an inductance L1, and the conductor structure 53 has an inductance L2. The capacitance C1 is generated by the first land 19, the second land 21, the first base material layer 11, and the second electrode 47. The RFIC chip 7 has an internal resistance R and a capacitance C2. The larger the capacitance C1, the larger the combined capacitance C and the lower the resonant frequency f. If the resonant frequency needs to be reduced with the communication frequency, this can be achieved by increasing the area of ​​the second electrode 47.

[0044] According to the RFID module 1A of the second embodiment, in the substrate 3A, the first base material layer 11 is arranged on the first main surface 3a side, and the second base material layer 13 is arranged on the second main surface 3b side. The RFID module 1A includes: the first ridge 19 arranged on the first main surface 3a side of the first base material layer 11 and connected to the first terminal 7a of the RFIC chip 7; the second ridge 21 arranged on the first main surface 3a side of the first base material layer 11 and connected to the second terminal 7b of the RFIC chip 7; the second electrode 47 associated with the first ridge 19 and the second ridge 21 and arranged on the first main surface 3a side of the second base material layer 13;the first interlayer connection conductor 55A and the second interlayer connection conductor 57A, which extend through the first base material layer 11 and the second base material layer 13, respectively; and the conductor pattern 53, which is arranged on the second main surface 3b side of the second base material layer 13 and connects the first interlayer connection conductor 55A and the second interlayer connection conductor 57A. The second ridge 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 ridge 19 and one end of the coil element 5 are connected to each other.

[0045] Since the capacitance C1 is generated by the first web 19, the second web 21, the first base material layer 11 and the second electrode 47, the resonance frequency of the RFID module 1A can be reduced.

[0046] The present invention is not limited to the above embodiments and may be modified as follows.

[0047] In the above embodiments, the coil element 5 has the second tightly wound portion 5b, but the present invention is not limited thereto. As shown in Fig. 9, a coil element 5D which does not have the second densely wound portion 5 and 5b may be used.

[0048] Although the present invention has been described in each of the embodiments with a certain degree of detail, the contents of the disclosure of these embodiments may vary in the details of configuration, and changes may be made in the combination and order of elements in each embodiment without departing from the scope and spirit of the invention as claimed. (Overview of implementation examples)

[0049] An RFID module of a first aspect according to 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 including a conductive wire wound multiple times. One end of the RFIC chip is electrically connected to one end of the coil element, while the other end of the RFIC chip is electrically connected to the other end of the coil element. The coil element includes at least one sparsely wound portion, both ends of the coil element being first densely wound portions in which the conductive wire is wound at a narrower pitch than in the sparsely wound portion.

[0050] In the RFID module of this aspect, because the coil element is wound with multiple conductor wires, the coil opening diameter can be made larger than that used with a coil element with legs. This makes it possible to downsize the RFID module while maintaining the antenna characteristics. Both ends of the coil element are first densely wound portions, where the conductor wires are wound at a narrower pitch than in the sparsely wound portion. The sparsely wound portion is wound at a wider pitch than in the first densely wound portion. Thus, the sparsely wound portion readily releases the magnetic field to the outside of the coil element, thereby acting as an antenna, and both ends, which are the first densely wound portions, can increase the fixing strength as connecting portions for the substrate.

[0051] According to a second aspect, in the RFID module of the first aspect, the length of the sparsely wound portion is proportionally larger than the length of the first densely wound portions in a winding axis direction of the coil element. Due to the coil element in which the sparsely wound portion is proportionally larger in length than the first densely wound portions, the RFID module can have improved antenna characteristics.

[0052] According to a third aspect, in the RFID module of the first aspect, the coil element has a second densely wound portion in which the conductive wire is wound at a narrower pitch than in the sparsely wound portion. This allows the second densely wound portion to act as a suction portion that is suctioned by a component attachment device.

[0053] According to a fourth aspect, in the RFID module of the third aspect, the length of the sparsely wound portion is proportionally larger than the sum of the length of the first densely wound portions and the length of the second densely wound portion in the winding axis direction of the coil element. Due to the coil element in which the length of the sparsely wound portion is proportionally larger than the sum of the length of the first densely wound portions and the length of the second densely wound portion, the RFID module can have improved antenna characteristics.

[0054] According to a fifth aspect, in the RFID module according to any one of the first to fourth aspects, the conductive wire of the coil element is covered with an insulating film. This increases the inductance component of the coil element, enabling shortening of the coil element and miniaturization of the RFID module.

[0055] According to a sixth aspect, in the RFID module according to any one of the first to fourth aspects, the conductive wire of the coil element is not covered with an insulating film. This makes it possible to omit a step of peeling off the insulating film at the hinge portions when attaching the coil element to the substrate via solder.

[0056] According to a seventh aspect, the RFID module of aspect 3 or 4 includes an auxiliary electrode disposed on one side of the first main surface of the substrate, and the second tightly wound portion is connected to the auxiliary electrode via solder. This makes it possible to prevent the coil element from sagging.

[0057] According to an eighth aspect, in the RFID module according to any one of the first to seventh aspects, the substrate comprises a first base material layer arranged on the first main surface side and a second base material layer arranged on the second main surface side.The RFID module includes: a first ridge disposed on one side of the first main surface of the first base material layer and connected to one end of the RFIC chip; a second ridge disposed on the side of the first main surface of the first base material layer and connected to the other end of the RFIC chip; a second electrode disposed on one side of the first main surface of the second main material layer and facing the first ridge and the second ridge; first and second interlayer connection conductors extending through the first base material layer and the second base material layer, respectively; and a conductor pattern disposed on one side of the second main surface of the second main material layer, the conductor pattern connecting the first interlayer connection conductor and the second interlayer connection conductor.The second ridge, the second electrode, and one end of the conductor pattern are connected via the first interlayer connecting conductor. The other end of the conductor pattern and the other end of the coil element are connected via the second interlayer connecting conductor, while the first ridge and one end of the coil element are connected to each other. Since capacitance is generated between the first ridge and the second electrode, and between the second ridge and the second electrode, the resonant frequency of the RFID module can be reduced.

[0058] 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. The third base material layer can protect the conductor pattern disposed on the second main surface side of the second base material layer. List of reference symbols 1.1A RFID module 3, 3A Substrat 5 coil element 5a first tightly wound section 5b second tightly wound section 5c sparsely wound section 7 RFIC chip 7a first connection 7b second connection 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 bridge 21 second bridge 23 Solder 27 first electrode 29 Auxiliary electrode 31 conductive wire 33 insulating film 47 second electrode 53 Ladder structure 55 first interlayer connecting conductor 57 second interlayer connection conductor 61 first main surface 62 second main surface 101 Metal plate Ia, Ib current QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2018 / 235714

[0004]

Claims

[1] An RFID module having the following features: a substrate having a first main surface and a second main surface facing each other; an RFIC chip arranged on the side of the first main surface of the substrate; and a coil element with a conductive wire wound several times, wherein one end of the RFIC chip is electrically connected to one end of the coil element, wherein the other end of the RFIC chip is electrically connected to the other end of the coil element, wherein the coil element has at least one sparsely wound section and wherein both ends of the coil element are first densely wound sections in which the conductive wire is wound at a narrower pitch than in the sparsely wound section. [2] The RFID module according to claim 1, wherein the length of the sparsely wound portion is proportionally larger than the length of the first densely wound portions in a winding axis direction of the coil element. [3] The RFID module according to claim 1, wherein the coil element has a second densely wound portion in which the conductive wire is wound at a narrower pitch than in the sparsely wound portion. [4] The RFID module according to claim 3, wherein the length of the sparsely wound portion is proportionally larger than the sum of the length of the first densely wound portions and the length of the second densely wound portion in a winding axis direction of the coil element. [5] The RFID module according to any one of claims 1 to 4, wherein the conductive wire of the coil element is covered with insulating film. [6] The RFID module according to any one of claims 1 to 4, wherein the conductive wire of the coil element is not covered with an insulating film. [7] The RFID module according to claim 3 or 4, comprising the following features: an auxiliary electrode arranged on the side of the first main surface of the substrate, wherein the second tightly wound section is connected to the auxiliary electrode via solder. [8] The RFID module according to any one of claims 1 to 7, wherein the substrate has a first base material layer arranged on the side of the first main surface and a second base material layer arranged on the side of the second main surface, wherein the RFID module has the following features: a first land disposed on one side of the first main surface 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 one side of the first main surface of the second main material layer and facing the first ridge and the second ridge; first and second interlayer connection conductors extending through the first base material layer and the second base material layer, respectively; and a conductor structure arranged on one side of the second main surface of the second main material layer, the conductor structure connecting the first interlayer connection conductor and the second interlayer connection conductor, wherein the second web, the second electrode and one end of the conductor structure are connected via the first interlayer connecting conductor, wherein the other end of the conductor structure and the other end of the coil element are connected via the second interlayer connecting conductor and wherein the first web and one end of the coil element are connected to each other. [9] The RFID module according to claim 8, wherein the substrate further comprises a third base material layer on which the second main surface side of the second base material layer is laminated.

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