RFID module

Abstract

The RFID module 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 formed by winding a lead wire a plurality of times. One end of the RFIC chip is electrically connected with one end of the coil element, and the other end of the RFIC chip is electrically connected with the other end of the coil element. The coil element has at least one sparsely wound portion, and both end portions of the coil element are first densely wound portions in which the pitch between the wires is narrower than 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, products are provided with RFID (Radio-Frequency Identification) modules as wireless communication devices for product management. One form of RFID modules is a form in which a coil conductor functioning as an antenna is arranged on an insulating substrate together with an RFIC (Radio-Frequency Integrated Circuit) chip.

[0003] For example, Patent Document 1 proposes an RFID module including a coil conductor formed by arranging coil prototypes having mounting legs in a row.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2018-235714 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] Since the coil conductor of the RFID module disclosed in Patent Document 1 has mounting legs, the coil opening diameter is reduced by an amount corresponding to the mounting space. In order to ensure antenna characteristics, the RFID module must be large.

[0009] An object of the present invention is to provide an RFID module that can be miniaturized while maintaining antenna characteristics.

[0010] Solutions for solving problems

[0011] An RFID module of a technical solution of the present invention includes: a substrate having a first main surface and a second main surface facing each other; an RFIC chip arranged on the first main surface side 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 sparsely wound portion, and both ends of the coil element are first densely wound portions in which the pitch between the conductors is narrower than that of the sparsely wound portion.

[0012] Effects of the Invention

[0013] According to the present invention, it is possible to provide an RFID module that can be reduced in size while maintaining antenna characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a longitudinal sectional view showing a schematic structure of the RFID module according to the first embodiment.

[0015] Figure 2 It is a three-dimensional diagram of a coil element.

[0016] Figure 3 It is a cross-sectional view of the conductor of the coil element.

[0017] Figure 4 It is a top view showing wiring electrodes on the substrate according to the first embodiment.

[0018] Figure 5 This is a top view illustrating the current flowing in the metal plate when the RFID module is placed on the metal plate.

[0019] Figure 6 This is a longitudinal cross-sectional view for explaining the current flowing through the metal plate when the RFID module is placed on the metal plate.

[0020] Figure 7 This is a longitudinal sectional view showing a schematic structure of an RFID module according to the second embodiment.

[0021] Figure 8 It is a plan view showing each base material layer of the laminated substrate.

[0022] Fig. 9 It is a longitudinal sectional view showing a schematic structure of an RFID module according to a modified example. DETAILED DESCRIPTION

[0023] The embodiments described below all represent a specific example of the present invention, and the present invention is not limited to this structure. In addition, the numerical values, shapes, structures, steps, the order of steps, etc. specifically shown in the following embodiments are examples and do not limit the present invention. For the constituent elements of the following embodiments that are not recorded in the independent claims representing the highest concept, they are described as arbitrary constituent elements. In addition, in all embodiments, the structures of the various modified examples are also the same, and the structures recorded in the various modified examples can also be combined respectively.

[0024] (Implementation Method 1)

[0025] Next, a schematic configuration of the RFID module 1 according to the first embodiment of the present invention will be described. Figure 1 This is a longitudinal sectional view of the RFID module 1 according to the first embodiment. Figure 2It is a three-dimensional diagram of a coil element. In the figure, the X-Y-Z coordinate system is used to make the invention easier to understand and does not limit the invention. The X-axis direction represents the length direction of the RFID module 1, the Y-axis direction represents the depth (width) direction, and the Z-axis direction represents the thickness direction. The X, Y, and Z directions are orthogonal to each other. In addition, in the embodiment, the positive direction of the Z axis is set to the upward direction and the negative direction of the Z axis is set to the downward direction for description.

[0026] 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 as 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 as input and output terminals. The substrate 3 of the embodiment 1 is a double-sided substrate, and the second main surface 62 and the first main surface 61 as the lower surface of the substrate 3 are opposite to each other. The substrate 3 is insulating, for example, a glass epoxy substrate, a ceramic substrate, etc.

[0027] A first resist layer 16 is stacked on the first main surface 61 of the substrate 3, and a second resist layer 17 is stacked on 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 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 described later. The first resist layer 16 and the second resist layer are, for example, insulating resin layers.

[0028] like Figure 1 and Figure 2 As shown, the coil element 5 is formed by winding the conductive wire 31 multiple times, and the coil element 5 functions as an antenna. The communication frequency band of the RFID module 1 of the embodiment is, for example, the UHF band of 860 MHz to 960 MHz. The number of turns and size of the coil element 5 can also be changed in accordance with the communication characteristics.

[0029] 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 a hollow 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 between the first densely wound portion 5a at both ends, for example, in the central portion 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 conductor 31 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 conductor 31 may be the same. In this case, the conductors 31 are in contact with each other in the first densely wound portion 5a and the second densely wound portion 5b.

[0030] 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, for example, twice or greater. In the first densely wound portion 5a, the number of turns of the conductive wire 31 is, for example, two or more.

[0031] Each first closely wound portion 5a is connected to the first pad (Japanese: ランド) 19 and the first electrode 27 arranged on the first main surface of the substrate 3 by means of the solder 23. In this way, the first closely wound portion 5a functions as a solder joint portion. The second closely wound portion 5b functions as an adsorbed portion when adsorbed to the component mounting machine, and can also be connected to the auxiliary electrode 29 arranged on the first main surface of the substrate 3 by means of the solder 23. Thus, the coil element 5 can be prevented from being bent when the resin layer 9 is molded. The length of the second closely wound portion 5b in the X-axis direction is larger than the aperture of the adsorption nozzle of the component mounting machine.

[0032] Reference Figure 3 . Figure 3 3 is a cross-sectional view of the wire 31 of the coil element 5. The wire 31 of the coil element 5 is covered with an insulating film 33. In addition, at the joint portion of the coil element 5 and the solder 23, the insulating film 33 is peeled off, and the wire 31 and the solder 23 are joined. The coil element 5 may also be composed of only the wire 31 not covered with the insulating film 33.

[0033] like Figure 1 As shown, 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 common sealing resin such as epoxy resin.

[0034] Next, refer to Figure 4 The substrate 3 will be described. Figure 4 It is a plan view showing the wiring electrodes on the substrate 3 . Figure 4 (a) is a plan view showing wiring electrodes on the first main surface 61 of the substrate 3 . Figure 4 (b) is a perspective plan view obtained by seeing through the substrate 3 , and shows the wiring electrodes on the second main surface 62 . Figure 4 The single-dot dash line in represents a through-hole connection.

[0035] like Figure 4 As shown in (a), the first pad 19 connected to the first terminal 7a of the RFIC chip 7 and the first closely wound portion 5a on the side closer to the RFIC chip 7 by means of the solder 23 and the second pad 21 connected to the second terminal 7b of the RFIC chip 7 by means of the solder 23 are arranged on the first main surface 61 as the upper surface of the substrate 3. In addition, the auxiliary electrode 29 connected to the second closely wound portion 5b by means of the solder 23 and the first electrode connected to the first closely wound portion 5a on the side farther from the RFIC chip 7 by means of the solder 23 are also arranged on the first main surface 61 of the substrate 3.

[0036] A first interlayer connection conductor 55 and a second interlayer connection conductor 57 are formed penetrating through the substrate 3. The first interlayer connection conductor 55 is a conductive path connecting the second pad 21 and the conductive pattern 53. The second interlayer connection conductor 57 is a conductive path connecting the first electrode 27 and the conductive pattern 53.

[0037] The first interlayer connection conductor 55 and the second interlayer connection conductor 57 are, for example, conductors formed by curing (metallizing) a conductive paste filled in a hole provided in the insulating substrate 3, but may also be plated through holes. The first interlayer connection conductor 55 and the second interlayer connection conductor 57 are arranged opposite to each other in the longitudinal direction of each of the third substrates.

[0038] A 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 is, for example, a straight line extending in the longitudinal direction of the substrate 3. Since the conductor pattern 53 is not arranged at a position further outward than the first interlayer connection conductor 55 and the second interlayer connection conductor 57 in the longitudinal direction, it is possible to prevent the conductor pattern 53 from being worn away when the RFID module comes into contact with other objects during the manufacturing process or post-manufacturing processing.

[0039] The first pads 19 , the second pads 21 , the first electrodes 27 , the auxiliary electrodes 29 , and the conductor pattern 53 are conductors, respectively, and are formed by patterning copper foil by, for example, photolithography.

[0040] Since an LC parallel resonant circuit is formed in the RFID module 1 and matches the radio wave of the communication frequency, current flows in the RFIC chip 7 when the coil element 5 receives the radio wave of the communication frequency.

[0041] like Figure 1 and Figure 2As shown, since the coil element 5 has the first densely wound portion 5a at both ends, it can be welded to the substrate 3, and the fixing strength of the coil element 5 can be improved. In addition, the coil element 5 has the sparsely wound portion 5c in which the conductive wire 31 is wound more sparsely than the first densely wound portion 5a at the parts other than the two ends. Since the coupling coefficient Ka between 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, it is easier to release the magnetic field from the sparsely wound portion 5c to the outside of the coil element 5 than the first densely wound portion 5a and the second densely wound portion 5b. In this way, since a large amount of magnetic field is released from the sparsely wound portion 5c, the performance of the coil element 5 as an antenna can be improved. In addition, in the winding axis direction of the coil element 5, the ratio of the length of the sparsely wound portion 5c is larger than the ratio of the length of the first densely wound portion 5a. In addition, in the winding axis direction of the coil element 5, the ratio of the length of the sparsely wound portion 5c is larger than the ratio of the sum of the length of the first densely wound portion 5a and the length of the second densely wound portion 5b. In this way, since the ratio of the length of the sparsely wound portion 5 c is large, a larger magnetic field can be released.

[0042] Reference Figure 5 and Figure 6 The current flowing through the metal plate 101 when the RFID module 1 is disposed on the metal plate 101 will be described. Figure 5 1 is a plan view for explaining currents Ia and Ib flowing through the metal plate 101 when the RFID module 1 is placed on the metal plate 101 . Figure 6 1 is a longitudinal cross-sectional view for explaining the current flowing in the metal plate 101 when the RFID module 1 is placed on the metal plate 101. Figure 5 In the figure, the substrate 3 is omitted for easy understanding of the flow of current.

[0043] 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 current Ia and the current 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 densely coiled portion 5b exists in the center of the coil element 5, it will not have a significant effect on the magnetic field coupling with the metal plate 101.

[0044] 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 formed by winding a plurality of conductors 31. 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 first densely wound portions 5a in which the conductors 31 are wound with a narrower pitch than the sparsely wound portion 5c.

[0045] According to the RFID module 1 of this structure, since the coil element 5 formed by winding the conductor 31 multiple times is adopted, the coil opening diameter can be increased compared with the use of a coil prototype body with legs, so that the miniaturization can be maintained while maintaining the antenna characteristics. In addition, the two ends of the coil element 5 are wound with a narrower pitch of the conductor 31 than the sparsely wound portion 5c, and the sparsely wound portion 5c is wound with a wider pitch of the conductor 31 than the two ends. Therefore, the sparsely wound portion is easy to release the magnetic field to the outside of the coil element 5, so it functions as an antenna, and the two ends that are wound more densely can improve the fixing strength as the connection part of the substrate 3.

[0046] In addition, the length ratio of the sparsely wound portion 5c is greater than the length ratio of the first densely wound portion 5a in the winding axis direction of the coil element 5. Since the length ratio of the sparsely wound portion 5c is greater than the length ratio of the first densely wound portion 5a, the antenna characteristics of the RFID module 1 can be improved.

[0047] The coil component 5 has the second densely wound portion 5b wound with a narrower pitch of the conductor 31 than the sparsely wound portion 5c. The coil component 5 has the second densely wound portion 5b, so that the second densely wound portion 5b can function as a suctioned portion suctioned to a component mounting machine.

[0048] Furthermore, the conductive wire 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 miniaturized.

[0049] Furthermore, the conductive wire 31 of the coil element 5 may not be covered with the insulating film 33. In this case, when mounting on the substrate 3 by soldering, it is possible to omit the step of peeling off the insulating film 33 at the joining portion.

[0050] (Implementation Method 2)

[0051] Next, refer to Figure 7 and Figure 8 An RFID module 1A according to the second embodiment will be described. Figure 7 This is a longitudinal sectional view schematically showing the structure of an RFID module 1A according to the second embodiment. Figure 8 It is a plan view showing each base material layer of the substrate 3A. Figure 8 (a) is a plan view showing wiring electrodes on the first main surface 61 of the substrate 3A. Figure 8 (b) is a plan view showing the wiring electrodes on the fifth main surface of the second base layer 13 . Figure 8 (c) is a perspective plan view obtained by seeing through the second base material layer 13, and shows the wiring electrodes on the sixth main surface 13b. Figure 8 (d) is a perspective plan view obtained by seeing through the third base material layer 15 , and shows the electrodes on the eighth main surface 15 b . Figure 8 The single-dot dash line in represents a through-hole connection.

[0052] The substrate 3A of the second embodiment is a laminated substrate, the first pad 19 extends to a position closer to the center of the length direction of the substrate 3 than the first embodiment, and the second electrode 47 capacitively coupled to the first pad 19 is provided in the substrate 3. With respect to the structure other than this point and the points described below, the RFID module 1A of the second embodiment is the same as the RFID module 1 of the first embodiment, and the description of the common structure is omitted.

[0053] The substrate 3A includes a first base layer 11, a second base layer 13, and a third base layer 15. The third base layer 15 is used as a bottom base layer, the second base layer 13 is stacked on the third base layer 15 toward the coil element 5, and the first base layer 11 is further stacked on the second base layer 13. The first base layer 11 to the third base layer 15 are insulating, for example, glass epoxy base material, ceramic base material, etc.

[0054] The third principal surface 11a of the first base material layer 11 corresponds to the first principal surface 61 of the substrate 3. The fourth principal surface 11b on the second principal surface 62 side of the first base material layer 11 is in contact with the fifth principal surface 13a on the first principal surface 61 side of the second base material layer 13. The sixth principal surface 13b on the second principal surface 62 side of the second base material layer 13 is in contact with the seventh principal surface 15a on the first principal surface 61 side of the third base material layer 15. The eighth principal surface 15b, which is the lower surface of the third base material layer 15, is opposite to the seventh principal surface 15a and corresponds to the second principal surface 62 of the substrate 3.

[0055] like Figure 8 As shown in (b), on the fifth main surface 13a which is the upper surface of the second base material layer 13, the second electrode 47 is arranged below the first pad 19 and the second pad 21. The second electrode 47 is opposite to the first pad 19 and the second pad 21, and the first pad 19 and the second pad 21 and the second electrode 47 generate a capacitance C1.

[0056] like Figure 7 and Figure 8As shown in FIG. 2 ( c ), a conductive pattern 53 is arranged on the sixth main surface 13 b which is the lower surface of the second base layer 13 . Figure 8 (c) is a view obtained by seeing through the fifth main surface 13a from above.

[0057] The substrate 3 has a first interlayer connection conductor 55A and a second interlayer connection conductor 57A that penetrate the first base material layer 11 and the second base material layer 13, respectively. The first interlayer connection conductor 55 is a conductive path that connects the first pad 19 to the second electrode 47 and the conductor pattern 53. The second interlayer connection conductor 57 is a conductive path that connects the first electrode 27 and the conductor pattern 53.

[0058] The first interlayer connection conductor 55A and the second interlayer connection conductor 57A are, for example, conductors formed by curing (metallizing) a conductive paste filled in holes provided in the insulating first base layer 11 and the second base layer 13, but may also be plated through holes. The first interlayer connection conductor 55A and the second interlayer connection conductor 57A are arranged opposite to each other in the longitudinal direction of the first base layer 11 and the second base layer 13, respectively.

[0059] The coil element 5 has an inductance L1, and the conductor pattern 53 has an inductance L2. The capacitor C1 is composed of the first pad 19, the second pad 21, the first substrate layer 11 and the second electrode 47. In addition, the RFIC chip 7 has a resistor R and a capacitor C2 inside. The larger the capacitor C1, the larger the composite capacitance C, and the smaller the resonant frequency f. In the case where the resonant frequency resonating with the communication frequency must be reduced, it can be dealt with by increasing the area of ​​the second electrode 47.

[0060] According to the RFID module 1A of the second embodiment, the substrate 3A has a first base layer 11 arranged on the first main surface 3a side and a second base layer 13 arranged on the second main surface 3b side. The RFID module 1A includes a first pad 19 arranged on the first main surface 3a side of the first base layer 11 and connected to the first terminal 7a of the RFIC chip 7, a second pad 21 arranged on the first main surface 3a side of the first base layer 11 and connected to the second terminal 7b of the RFIC chip 7, a second electrode 47 opposite to the first pad 19 and the second pad 21 and arranged on the first main surface 3a side of the second base layer 13, a first interlayer connection conductor 55A and a second interlayer connection conductor 57A respectively penetrating the first base layer 11 and the second base layer 13, and a conductor pattern 53 arranged on the second main surface 3b side of the second base layer 13 and connecting the first interlayer connection conductor 55A and the second interlayer connection conductor 57A. The second pad 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 pad 19 and one end of the coil element 5 are connected.

[0061] Since the capacitance C1 formed by the first pad 19 , the second pad 21 , the first base material layer 11 , and the second electrode 47 is generated, the resonance frequency of the RFID module 1A can be reduced.

[0062] The present invention is not limited to the configurations of the above-described embodiments, and can be implemented in the following modified forms.

[0063] In the above-mentioned embodiments, the coil element 5 has the second densely wound portion 5b, but the present invention is not limited thereto. Fig. 9 The coil component 5D shown here does not have the second densely coiled portion 5b.

[0064] The present invention is described in detail to a certain extent in each embodiment, but the disclosure of the above-mentioned embodiment can be changed in structural details, and the combination and order of elements of each embodiment can be changed without departing from the scope and concept of the claimed invention.

[0065] (Overview of Embodiments)

[0066] The RFID module of the first technical solution of the present invention includes: a substrate having a first main surface and a second main surface opposite to each other; an RFIC chip arranged on the first main surface side 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 sparsely wound portion, and both ends of the coil element are first densely wound portions in which the pitch between the conductors is narrower than that of the sparsely wound portion.

[0067] In the RFID module of this technical solution, since a coil element formed by winding a conductor multiple times is used, the coil opening diameter can be increased compared to using a coil prototype body with legs. As a result, the RFID module can be miniaturized while maintaining antenna characteristics. The two ends of the coil element are the first densely wound portion in which the pitch between the conductors is narrower than that of the sparsely wound portion. The sparsely wound portion is wound with a wider pitch between the conductors than the first densely wound portion. Therefore, it is easy to release the magnetic field to the outside of the coil element in the sparsely wound portion, so that it functions as an antenna, and the two ends of the first densely wound portion as connecting parts of the substrate can improve the fixing strength.

[0068] According to the second technical solution, in the RFID module of the first technical solution, in the winding axis direction of the coil element, the ratio of the length of the sparsely wound portion is greater than the ratio of the length of the first densely wound portion. Since the ratio of the length of the sparsely wound portion in the coil element is greater than the ratio of the length of the first densely wound portion, the antenna characteristics of the RFID module can be improved.

[0069] According to the third aspect, the RFID module of the first aspect includes a second densely wound portion wound with a narrower wire pitch than the sparsely wound portion. Thus, the second densely wound portion can function as a suctioned portion suctioned to a component mounting machine.

[0070] According to the fourth technical solution, in the RFID module of the third technical solution, in the winding axis direction of the coil element, the ratio of the length of the sparsely wound portion is greater than the ratio of the sum of the length of the first densely wound portion and the length of the second densely wound portion. Since the ratio of the length of the sparsely wound portion in the coil element is greater than the ratio of 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.

[0071] According to the fifth aspect, in the RFID module of any one of the first to fourth aspects, the conductive wire of the coil element is covered with an insulating film. This can increase the inductance component of the coil element, thereby shortening the length of the coil element and miniaturizing the RFID module.

[0072] According to the sixth aspect, in the RFID module of any one of the first to fourth aspects, the conductive wire of the coil element is not covered with an insulating film. This can omit the step of peeling off the insulating film at the joint portion when mounting on the substrate by solder.

[0073] According to a seventh aspect, in the RFID module of the third aspect or the fourth aspect, an auxiliary electrode is provided on the first main surface side of the substrate, and the second closely wound portion is connected to the auxiliary electrode via solder. This can prevent the coil element from being bent.

[0074] According to the eighth technical solution, in the RFID module of any one of the first technical solution to the seventh technical solution, the substrate has a first substrate layer arranged on the first main surface side and a second substrate layer arranged on the second main surface side. The RFID module includes: a first pad arranged on the first main surface side of the first substrate layer, connected to one end of the RFIC chip; a second pad arranged on the first main surface side of the first substrate layer, connected to the other end of the RFIC chip; a second electrode arranged on the first main surface side of the second substrate layer opposite to the first pad and the second pad; a first interlayer connection conductor and a second interlayer connection conductor, the first interlayer connection conductor and the second interlayer connection conductor respectively penetrating the first substrate layer and the second substrate layer; and a conductor pattern arranged on the second main surface side of the second substrate layer, connecting the first interlayer connection conductor and the second interlayer connection conductor. The second pad, the second electrode, and one end of the conductor pattern are connected by means of 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 pad and one end of the coil element are connected. Since capacitance is generated between the first pad and the second pad and the second electrode, the resonance frequency of the RFID module can be reduced.

[0075] According to a ninth aspect, in the RFID module of the eighth aspect, the substrate further includes a third base layer on the second main surface side of the second base layer. The third base layer can protect the conductor pattern arranged on the second main surface side of the second base layer.

[0076] Description of Reference Numerals

[0077] 1, 1A, RFID module; 3, 3A, substrate; 5, coil element; 5a, first densely wound portion; 5b, second densely wound portion; 5c, sparsely wound portion; 7, RFIC chip; 7a, first terminal; 7b, second terminal; 9, resin layer; 11, first substrate layer; 11a, third main surface; 11b, fourth main surface; 13, second substrate layer; 13a, fifth main surface; 13b, sixth main surface; 15, third substrate layer; 15a, seventh main surface surface; 15b, the 8th main surface; 16, the 1st anti-etching layer; 17, the 2nd anti-etching layer; 19, the 1st pad; 21, the 2nd pad; 23, solder; 27, the 1st electrode; 29, the auxiliary electrode; 31, the wire; 33, the insulating film; 47, the 2nd electrode; 53, the conductor pattern; 55, the 1st interlayer connecting conductor; 57, the 2nd interlayer connecting conductor; 61, the 1st main surface; 62, the 2nd main surface; 101, the metal plate; Ia, Ib, the current.

Claims

1. An RFID module, wherein: The RFID module 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 Coil components are made by winding a wire 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 portion. Both ends of the coil element are first densely wound portions wound with a narrower wire pitch than the sparsely wound portions.

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

3. The RFID module according to claim 1, wherein: The RFID module includes a second densely wound portion in which the wire pitch is wound narrower than that of the sparsely wound portion.

4. The RFID module according to claim 3, wherein: In the winding axis direction of the coil element, a ratio of the length of the sparsely wound portion is greater than a ratio of a sum of a length of the first densely wound portion and a length of the second densely wound portion.

5. The RFID module according to any one of claims 1 to 4, wherein: The conductive wire of the coil element is covered with an 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, wherein: The RFID module includes an auxiliary electrode disposed on the first main surface side of the substrate. The second closely wound portion is connected to the auxiliary electrode via solder.

8. The RFID module according to any one of claims 1 to 7, wherein: The substrate includes 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 comprises: a first pad disposed on the first main surface side of the first base layer and connected to one end of the RFIC chip; a second pad 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 the first main surface side of the second base material layer, facing the first pad and the second pad; a first interlayer connection conductor and a second interlayer connection conductor, the first interlayer connection conductor and the second interlayer connection conductor respectively penetrating the first base material layer and the second base material layer; and 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 pad, 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 pad is connected to one end of the coil element.

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

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