JP2024122288A - Antenna device and IC card equipped with same - Google Patents

Abstract

To improve an antenna device equipped with a coil pattern provided on a base material and a magnetic body covering the base material.SOLUTION: An antenna device 1 includes a magnetic body 30 covering a main surface 22 of a base material 20 and having a through hole 31, and a coil pattern CP provided on the base material 20 so that it overlaps the magnetic body 30 as viewed from a Z direction. The coil pattern CP includes a first circling portion 110 and a second circling portion 120 disposed within an opening 110a of the first circling portion 110 as viewed from the Z direction. The second circling portion 120 includes a first portion 121 provided on a main surface 21 and circling along the perimeter of the through hole 31 of the magnetic body 30, and a second portion 122 provided on the main surface 22 and circling along the perimeter of the through hole 31 of the magnetic body 30. This allows a sufficient number of turns of the second circling portion 120 to be secured.SELECTED DRAWING: Figure 3

Description

This disclosure relates to an antenna device and an IC card equipped with the same.

Patent document 1 discloses an antenna device that includes coil patterns provided on both sides of a substrate and a magnetic body that covers the other surface of the substrate. The antenna device described in patent document 1 has an opening in the magnetic body in the area that overlaps with the IC module to enable magnetic coupling with the IC module.

JP 2020-195050 A

The present disclosure aims to provide an improved antenna device that includes a coil pattern provided on a substrate and a magnetic body that covers the substrate.

An antenna device according to one embodiment of the present disclosure includes a substrate having first and second principal surfaces located opposite each other, a magnetic body covering the second principal surface of the substrate and having a through hole, and a coil pattern provided on the first and second principal surfaces of the substrate so as to overlap with the magnetic body when viewed from the thickness direction of the substrate, the coil pattern including a first winding portion provided on the first or second principal surface and a second winding portion disposed within an opening of the first winding portion when viewed from the thickness direction of the substrate, the second winding portion including a first portion provided on the first principal surface and winding around the periphery of the through hole of the magnetic body, and a second portion provided on the second principal surface and winding around the periphery of the through hole of the magnetic body.

This disclosure makes it possible to provide an improved antenna device that includes a coil pattern provided on a substrate and a magnetic body that covers the substrate.

FIG. 1 is a schematic perspective view showing the appearance of an IC card 3 equipped with an antenna device according to an embodiment of the present disclosure. FIG. 2 is a schematic exploded perspective view for explaining the structure of an IC card 3 including an antenna device 1 according to an embodiment of the present disclosure. FIG. 3 is a schematic cross-sectional view for explaining the structure of an IC card 3 including an antenna device 1 according to an embodiment of the present disclosure. FIG. 4 is a schematic plan view of the conductor pattern formed on the first main surface 21 of the substrate 20. As shown in FIG. FIG. 5 is a schematic plan view of the conductor pattern formed on the second main surface 22 of the base material 20. As shown in FIG. FIG. 6 is a schematic perspective view of the IC module 50 as viewed from the rear side. FIG. 7 is a schematic diagram showing a state in which the IC card 3 and the card reader 6 communicate with each other. FIG. 8 is a schematic plan view for illustrating a pattern shape of the first portion 121 of the second winding portion 120 according to a modified example. FIG. 9 is a schematic plan view for illustrating a pattern shape of the second portion 122 of the second winding portion 120 according to a modified example. FIG. 10 is a schematic plan view for explaining a method of forming the second circumferential portion 120 according to a modified example. FIG. 11 is a schematic cross-sectional view for explaining the structure of an IC card 3A including an antenna device 1A according to a first modified example. FIG. 12 is a partial enlarged view of the antenna device 1A. FIG. 13 is a schematic cross-sectional view for explaining the structure of an IC card 3B including an antenna device 1B according to the second modified example. FIG. 14 is a schematic cross-sectional view for explaining the structure of an IC card 3C including an antenna device 1C according to the third modified example. FIG. 15 is a schematic plan view for illustrating the pattern shape of first portion 121 of second winding portion 120 in antenna device 1C according to the third modified example. FIG. 16 is a schematic plan view for illustrating the pattern shape of second portion 122 of second winding portion 120 in antenna device 1C according to the third modified example. FIG. 17 is a schematic cross-sectional view for explaining the structure of an IC card 3D equipped with an antenna device 1D according to the fourth modification.

Embodiments of the present disclosure will be described in detail below with reference to the attached drawings.

Figure 1 is a simplified perspective view showing the appearance of an IC card 3 equipped with an antenna device according to one embodiment of the present disclosure.

As shown in FIG. 1, the IC card 3 according to this embodiment is a plate-like body with the Y direction as the longitudinal direction, the X direction as the lateral direction, and the Z direction as the thickness direction, and has a top surface 3a and a back surface 3b that form the XY plane. The IC card 3 has an IC module built in, which will be described later, and the terminal electrodes E of the IC module are exposed on the top surface 3a of the IC card 3.

Figures 2 and 3 are respectively a simplified exploded perspective view and a simplified cross-sectional view illustrating the structure of an IC card 3 equipped with an antenna device 1 according to one embodiment of the present disclosure.

The IC card 3 shown in Figures 2 and 3 has a structure in which a plastic plate 10, a base material 20, a magnetic body 30, and a metal plate 40 are layered in this order from the back surface 3b side to the top surface 3a side. The plastic plate 10 is made of a resin material that does not impede magnetic flux. The surface of the plastic plate 10 forms the back surface 3b of the IC card 3. The metal plate 40 is made of a metal material such as stainless steel or titanium. The surface of the metal plate 40 forms the top surface 3a of the IC card 3. A through hole 41 is provided in the metal plate 40, and an IC module 50 is arranged inside the through hole 41. In this way, the IC card 3 is a card in which a metal plate is used for the main body.

The substrate 20 is a film made of an insulating resin material, and the coil pattern CP is formed by a conductor pattern formed on the first and second main surfaces 21, 22 located on opposite sides. Examples of conductive materials that constitute the conductor pattern include copper, aluminum, and alloys thereof. Examples of insulating resin materials that constitute the film-like substrate 20 include PET (polyethylene terephthalate) and PI (polyimide). The first main surface 21 of the substrate 20 faces the plastic plate 10, and the second main surface 22 of the substrate 20 faces the metal plate 40 via the magnetic body 30. The plastic plate 10 and the substrate 20 are bonded via an adhesive layer 61. The coil pattern CP may include a pattern made of conductive resin between the conductor pattern and the substrate 20. In this case, the coil pattern CP has a structure in which a pattern made of conductive resin and a conductor pattern are laminated in this order on the first and second main surfaces 21, 22 of the substrate 20.

The other main surface 22 of the substrate 20 is covered with a magnetic body 30. In this embodiment, in a plan view from the Z direction, which is the thickness direction, all of the conductor patterns provided on the substrate 20 overlap with the magnetic body 30. The magnetic body 30 is not a sheet-like member attached to the substrate 20 using an adhesive layer or the like, but is a paste-like member made of a mixture of magnetic particles and resin that is applied to the second main surface 22 of the substrate 20 and hardened. For this reason, the coil pattern provided on the second main surface 22 of the substrate 20 is at least partially embedded in the magnetic body 30 so that not only the top surface (XY surface) located on the opposite side to the bottom surface (XY surface) in contact with the second main surface 22 of the substrate 20, but also the side surface (mainly along the Z direction) connecting the bottom surface and the top surface are covered with the magnetic body 30. In this embodiment, the magnetic body 30 is formed by applying a paste-like material made of a mixture of magnetic particles and resin to the second main surface 22 of the substrate 20, so there is no need for an adhesive layer to bond the substrate 20 and the magnetic body 30, and the overall thickness can be reduced accordingly.

The magnetic body 30 is adhered to the metal plate 40 via an adhesive layer 62. The base material 20 and the magnetic body 30 are provided with through holes 23, 31 at positions overlapping with the through hole 41 of the metal plate 40. The antenna device 1 according to this embodiment is composed of at least the base material 20 and the coil pattern CP formed on its main surfaces 21, 22, and the magnetic body 30 covering the second main surface 22 of the base material 20. The through hole 41 provided in the metal plate 40 and the through holes 23, 31 provided in the base material 20 and the magnetic body 30 are approximately the same size. Therefore, the coil pattern CP formed on the main surfaces 21, 22 of the base material 20 does not overlap with the through hole 41 of the metal plate 40 in a plan view seen from the Z direction.

When manufacturing an antenna device 1 having such a configuration, first, a conductor pattern is formed on the first and second main surfaces 21, 22 of the substrate 20, and then a paste-like material made of a mixture of magnetic particles and resin is applied to the entire surface of the other main surface 22 of the substrate 20, and the magnetic body 30 is formed by hardening the paste-like material. Next, the through holes 23, 31 are simultaneously formed in the substrate 20 and the magnetic body 30 by punching using a mold or the like. As a result, when viewed from the Z direction, the inner circumferential surface of the through hole 23 in the substrate 20 and the inner circumferential surface of the through hole 31 in the magnetic body 30 form the same surface.

Figure 4 is a schematic plan view of the conductor pattern formed on the first main surface 21 of the substrate 20.

As shown in FIG. 4, the first main surface 21 of the substrate 20 is provided with a first winding portion 110 of the coil pattern CP, a first portion 121 constituting a part of the second winding portion 120 of the coil pattern CP, and capacitor patterns 131 and 133. The first winding portion 110 is a pattern that winds around the outer edge of the substrate 20 for about three turns, and the first portion 121 of the second winding portion 120 and the capacitor patterns 131 and 133 are arranged within the opening 110a. The opening 110a is an area surrounded by the innermost turn of the first winding portion 110 of the coil pattern CP. The first portion 121 of the second winding portion 120 is a pattern that winds around the periphery of the through hole 31 of the magnetic body 30 for about three turns, and the pattern width is narrower than the pattern width of the first winding portion 110. This allows each turn constituting the first portion 121 of the second winding portion 120 to be closer to the edge of the through hole 31 of the magnetic body 30, enhancing the coupling with the coupling coil 53 in the IC module 50 described below.

The capacitor pattern 131 is a pattern branched in the X direction from the innermost turn of the first winding part 110. In the example shown in FIG. 4, 16 capacitor patterns 131 branch from the innermost turn of the first winding part 110, but the number of capacitor patterns 131 is not particularly limited. In addition, multiple capacitor patterns 133 branch from one capacitor pattern 131. All of the capacitor patterns 133 extend in the Y direction. In the example shown in FIG. 4, 12 capacitor patterns 133 branch from one capacitor pattern 131, but the number of capacitor patterns 133 is not particularly limited. Note that the capacitor patterns 131 and 133 may include a pattern made of conductive resin between the conductor pattern and the substrate 20. In this case, the capacitor patterns 131 and 133 have a structure in which a pattern made of conductive resin and a conductor pattern are laminated in this order on the first main surface 21 of the substrate 20.

Figure 5 is a schematic plan view of the conductor pattern formed on the second main surface 22 of the substrate 20.

As shown in FIG. 5, the second main surface 22 of the substrate 20 is arranged at a position overlapping with the opening 110a of the first winding portion 110 in a plan view from the Z direction, and includes a second portion 122 constituting the remaining portion of the second winding portion 120, capacitor patterns 132, 134, and a connection pattern 140. The second portion 122 of the second winding portion 120 is a pattern that winds around the periphery of the through hole 31 of the magnetic body 30 for approximately three turns, and the pattern width is the same as the pattern width of the first portion 121 of the second winding portion 120.

The planar positions of the capacitor patterns 132 and 134 are aligned with the capacitor patterns 131 and 133, respectively. That is, the capacitor patterns 131 and 132 face each other through the substrate 20, and the capacitor patterns 133 and 134 face each other through the substrate 20. As a result, the capacitor C is formed by the capacitor patterns 131 and 133 provided on the first main surface 21 of the substrate 20, the capacitor patterns 132 and 134 provided on the second main surface 22 of the substrate 20, and the substrate 20 located between them. The capacitance of the capacitor C having such a pattern shape can be finely adjusted by removing some of the capacitor patterns 133 by trimming. The capacitor patterns 132 and 134 may include a pattern made of conductive resin between the conductor pattern and the substrate 20. In this case, the capacitor patterns 132 and 134 have a structure in which a pattern made of conductive resin and a conductor pattern are laminated in this order on the second main surface 22 of the substrate 20.

4 and 5, the outer peripheral end of the first winding part 110 is connected to the capacitor patterns 132 and 134 through a via conductor 151 provided through the substrate 20. In addition, a part of the second turn counting from the outermost turn (the second turn counting from the innermost turn) of the turns constituting the first winding part 110 is cut off. One end and the other end of the cut off part are respectively connected to via conductors 152 and 153 provided through the substrate 20. The via conductor 152 is connected to one end of the connection pattern 140. The other end of the connection pattern 140 is connected to a via conductor 154 provided through the substrate 20. The via conductor 154 is connected to the outer peripheral end of the first part 121 of the second winding part 120. The inner peripheral end of the first part 121 of the second winding part 120 is connected to a via conductor 155 provided through the substrate 20. The via conductor 155 is connected to the inner peripheral end of the second portion 122 of the second winding portion 120. The outer peripheral end of the second portion 122 of the second winding portion 120 is connected to the via conductor 153. In this way, the second winding portion 120 is connected to the middle of the turn from the outer peripheral end to the inner peripheral end of the first winding portion 110. This allows the second winding portion 120, through which current easily flows, to be positioned closer to the center of the line length of the coil pattern, so that the power received from the coupling coil 53 in the IC module 50 described later can be used efficiently, thereby expanding the communication distance. The connection pattern 140 may include a pattern made of conductive resin between the conductor pattern and the substrate 20. In this case, the connection pattern 140 has a structure in which a pattern made of conductive resin and a conductor pattern are laminated in this order on the second main surface 22 of the substrate 20.

With this configuration, the first winding portion 110 and the second winding portion 120 of the coil pattern CP are connected in series, and the capacitor C is connected to both ends of the first winding portion 110. The coil pattern CP and the capacitor C form a closed circuit that is not connected to an external circuit. The capacitor C plays a role in improving communication characteristics by adjusting the resonant frequency. Then, by setting the resonant frequency of this closed circuit to 13.56 MHz or a frequency band near 13.56 MHz, near field communication (NFC) becomes possible.

Figure 6 is a simplified perspective view of the IC module 50 seen from the back side.

As shown in FIG. 6, the IC module 50 includes a module substrate 51, an IC chip 52 mounted or built into the module substrate 51, and a coupling coil 53. The IC chip 52 is protected by being covered with a dome-shaped protective resin 54. The protective resin 54 is made of an insulating material, and as shown in FIG. 3, a part of it may be disposed in the through holes 23 and 31. The terminal electrode E shown in FIG. 1 is provided on the back side of the module substrate 51. The IC module 50 having such a configuration is accommodated in the through hole 41 provided in the metal plate 40. When the IC module 50 is accommodated in the through hole 41, the coupling coil 53 and the second winding part 120 of the coil pattern CP provided on both sides of the substrate 20 are electromagnetically coupled. And, since the second winding part 120 is connected in series to the first winding part 110, the IC module 50 can communicate with the outside via the first winding part 110 and the second winding part 120.

As a result, as shown in FIG. 7, by facing the back surface 3b of the IC card 3 to the card reader 6, communication can be performed between the card reader 6 and the IC chip 52. In other words, the card reader 6 is coupled to the coupling coil 53 of the IC module 50 via the first winding portion 110 and the second winding portion 120 of the coil pattern CP, thereby achieving communication with the IC chip 52.

As described above, in the antenna device 1 according to this embodiment, the magnetic body 30 is applied to the entire surface of the second main surface 22 of the substrate 20, and then the through holes 23 and 31 are formed by punching, so that all of the conductor patterns formed on the substrate 20 overlap with the magnetic body 30 when viewed from the Z direction. Here, the magnetic body 30 functions as a magnetic path that increases the inductance of the first winding portion 110 of the coil pattern CP, while it can be a factor that inhibits the coupling with the coupling coil 53 of the IC module 50 for the second winding portion 120 of the coil pattern CP. However, in this embodiment, the second winding portion 120 of the coil pattern CP is formed on both sides of the substrate 20, and this allows the second winding portion 120 to be close to the through hole 31 of the magnetic body 30 while ensuring a sufficient number of turns, so that the inductance can be increased and the coupling with the coupling coil 53 of the IC module 50 can be ensured.

In addition, the punching process not only forms the through hole 31 in the magnetic body 30, but also the through hole 23 in the base material 20, so that the dome-shaped protective resin 54 covering the IC chip 52 does not interfere with the base material 20. In this embodiment, the first winding portion 110 is formed on the first main surface 21 of the base material 20, but the first winding portion 110 may be formed on the second main surface 22 of the base material 20.

Figures 8 and 9 are schematic plan views illustrating the pattern shapes of the first and second parts 121 and 122 of the second circumferential portion 120 according to modified examples.

8 and 9, the pattern width of the innermost turns 121a, 122a of the first and second parts 121, 122 of the second winding part 120 is wider than the pattern width of the other turns, and the inner circumferential surfaces of the innermost turns 121a, 122a are flush with the inner circumferential surfaces of the through holes 23, 31 of the substrate 20 and the magnetic body 30. In other words, the position of the inner circumferential edge of the innermost turns 121a, 122a of the first and second parts 121, 122 coincides with the planar position of the inner circumferential edges of the through holes 23, 31 of the substrate 20 and the magnetic body 30, and the substrate 20 does not exist inside the inner circumferential edges of the innermost turns 121a, 122a of the first and second parts 121, 122.

As shown in FIG. 10, such a configuration can be obtained by selectively expanding the pattern width of the innermost turn 121a of the first part 121 of the second winding part 120 so that the opening size of the first part 121 of the second winding part 120 is smaller than the opening size of the through holes 23, 31, and punching the through holes 23, 31 at the position indicated by the symbol A that overlaps with the innermost turn 121a. This not only reduces the resistance value of the second winding part 120, but also enhances the coupling with the coupling coil 53 of the IC module 50, since the inner circumferential surfaces of the innermost turns 121a, 122a of the first and second parts 121, 122 are exposed to the through holes 23, 31 without being covered by the magnetic body 30.

Figure 11 is a schematic cross-sectional view illustrating the structure of an IC card 3A equipped with an antenna device 1A according to a first modified example of this embodiment.

As shown in FIG. 11, the antenna device 1A according to the first modified example differs from the antenna device 1 shown in FIG. 3 in that an insulating layer 70 is provided on the second main surface 22 of the substrate 20 so as to cover the conductor pattern provided on the second main surface 22 of the substrate 20. Since the other basic configuration is the same as that of the antenna device 1 shown in FIG. 3, the same elements are given the same reference numerals and redundant explanations are omitted.

The insulating layer 70 plays a role in preventing short circuits between the turns of the second part 122 through the magnetic body 30 by covering at least the surface of the second part 122 of the second winding part 120. By providing such an insulating layer 70, it is possible to prevent short circuits between the turns even when the space between the turns of the second part 122 is narrow and the insulating properties of the magnetic body 30 are low. In this embodiment, since the magnetic body 30 is formed by coating, the insulating layer 70 does not need to have the function of bonding the base material 20 and the magnetic body 30. In addition, it is not necessary to form the insulating layer 70 on the entire second main surface 22 of the base material 20, and the insulating layer 70 may be selectively formed on the surface of the second part 122 of the second winding part 120. In addition, in this embodiment, since the insulating layer 70 covers the surface of the second part 122 of the second winding part 120, the magnetic body 30 covers the upper surface and part of the side surface of the second part 122 of the second winding part 120.

Also, as shown in the enlarged view of FIG. 12, the thickness of the insulating layer 70 may be greater than the thickness T1 between the second portion 122 of the second winding portion 120 and the magnetic body 30, i.e., the thickness T2 between the substrate 20 and the magnetic body 30. This makes it possible to improve the flatness of the magnetic body 30.

Figure 13 is a schematic cross-sectional view illustrating the structure of an IC card 3B equipped with an antenna device 1B according to a second modified example of this embodiment.

As shown in FIG. 13, the antenna device 1B according to the second modified example differs from the antenna device 1 shown in FIG. 3 in that the through holes 23, 31 provided in the substrate 20 and the magnetic body 30 are tapered. The other basic configuration is the same as that of the antenna device 1 shown in FIG. 3, so the same elements are given the same reference numerals and redundant explanations are omitted.

This tapered shape is obtained by punching the through holes 23, 31 with the magnetic body 30 on the die side and the first main surface 21 of the substrate 20 on the punch side. By using this shape, the opening width of the through hole 31 in the magnetic body 30 becomes narrower as it moves away from the substrate 20, preventing deterioration of the antenna characteristics. In addition, the opening width of the through hole 23 in the substrate 20 also becomes narrower as it moves closer to the magnetic body 30.

Figure 14 is a schematic cross-sectional view for explaining the structure of an IC card 3C equipped with an antenna device 1C according to a third modified example of this embodiment. Also, Figures 15 and 16 are schematic plan views for explaining the pattern shapes of the first and second parts 121, 122 of the second winding part 120 in the antenna device 1C according to the third modified example.

As shown in Figures 14 to 16, the antenna device 1C according to the third modification differs from the antenna device 1B according to the second modification shown in Figure 13 in that the first and second parts 121, 122 of the second winding portion 120 each have approximately one turn. Since the other basic configurations are the same as those of the antenna device 1B according to the second modification, the same elements are given the same reference numerals and redundant explanations are omitted.

As illustrated in the third modified example, the first and second parts 121, 122 of the second winding part 120 do not need to be multiple turns, and may be about one turn. In this case, there is no need to add the insulating layer 70 shown in FIG. 11 because there is no decrease in insulation resistance between the turns of the second part 122, which can be a problem when there are multiple turns. Also, in the third modified example, the winding direction of the second winding part 120 is opposite to the winding direction of the first winding part 110. In this way, the winding direction of the second winding part 120 does not need to be the same as the winding direction of the first winding part 110.

Figure 17 is a schematic cross-sectional view illustrating the structure of an IC card 3D equipped with an antenna device 1D according to a fourth modified example of this embodiment.

As shown in FIG. 17, the antenna device 1D according to the fourth modification differs from the antenna device 1B according to the second modification shown in FIG. 13 in that the second portion 122 of the second winding portion 120 is approximately one turn. The other basic configuration is the same as that of the antenna device 1B according to the second modification, so the same elements are given the same reference numerals and duplicate explanations are omitted.

As illustrated in the fourth modified example, the number of turns of the first and second parts 121, 122 of the second winding part 120 may be different from each other. In the example shown in FIG. 17, the number of turns of the second part 122 of the second winding part 120 is less than the number of turns of the first part 121 of the second winding part 120. This eliminates the need to add the insulating layer 70 shown in FIG. 11, since the insulation resistance between the turns of the second part 122, which can be a problem when there are multiple turns, does not decrease. In addition, the resistance value of the second part 122 can be reduced, and the number of turns of the first part 121, which is farther from the magnetic body 30 than the second part 122, is sufficiently secured, thereby enhancing the coupling with the coupling coil 53 of the IC module 50.

In addition, in the example shown in FIG. 17, the pattern width of the second portion 122 of the second winding portion 120 is wider than the pattern width of the first portion 121 of the second winding portion 120, and one turn constituting the second portion 122 of the second winding portion 120 overlaps with all turns constituting the first portion 121 of the second winding portion 120. This makes it possible to suppress fluctuations in parasitic capacitance caused by relative pattern misalignment between the first portion 121 and the second portion 122.

Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the present disclosure, and it goes without saying that these modifications are also included within the scope of the present disclosure.

The technology disclosed herein includes, but is not limited to, the following configuration examples:

An antenna device according to one embodiment of the present disclosure includes a substrate having first and second main surfaces located opposite each other, a magnetic body covering the second main surface of the substrate and having a through hole, and a coil pattern provided on the first and second main surfaces of the substrate so as to overlap with the magnetic body when viewed from the thickness direction of the substrate, the coil pattern including a first winding portion provided on the first or second main surface and a second winding portion disposed within an opening of the first winding portion when viewed from the thickness direction of the substrate, the second winding portion including a first portion provided on the first main surface and winding around the periphery of the through hole of the magnetic body, and a second portion provided on the second main surface and winding around the periphery of the through hole of the magnetic body. This allows a sufficient number of turns of the second winding portion to be secured, so that even when the second winding portion overlaps with the magnetic body, it is possible to couple with an IC module.

In the above antenna device, the second portion of the second winding portion has a bottom surface that contacts the second main surface of the substrate, a top surface located opposite the bottom surface, and a side surface that connects the bottom surface and the top surface, and at least a portion of the top surface and the side surface may be embedded in the magnetic material so that at least a portion of the top surface and the side surface are covered with the magnetic material. This makes it possible to reduce the overall thickness.

In the above antenna device, the substrate has a through hole that overlaps with the through hole of the magnetic material, and when viewed from the thickness direction, the inner peripheral surface of the through hole of the magnetic material and the inner peripheral surface of the through hole of the substrate may form the same surface. This structure can be obtained by punching, and can prevent interference between the substrate and devices such as IC modules placed in the through hole.

In the above antenna device, the inner circumferential surface of the innermost turn of the first or second part of the second winding section may be flush with the inner circumferential surfaces of the through hole of the magnetic material and the through hole of the base material when viewed from the thickness direction. This enhances the coupling with the IC module.

The antenna device may further include an insulating layer located between the second portion of the second winding part and the magnetic body. This makes it possible to prevent short circuits between the turns constituting the second portion. In this case, the insulating layer may be thicker between the turns of the second portion than it is between the second portion of the second winding part and the magnetic body. This makes it possible to increase the flatness of the magnetic body.

In the above antenna device, the number of turns in the second portion of the second winding portion may be less than the number of turns in the first portion of the second winding portion. This makes it possible to reduce the resistance value of the second portion while ensuring a sufficient number of turns in the first portion.

In the above antenna device, the second portion of the second winding portion may have a pattern width wider than the first portion of the second winding portion, and one turn constituting the second portion of the second winding portion may overlap multiple turns constituting the first portion of the second winding portion. This makes it possible to suppress fluctuations in parasitic capacitance caused by relative pattern misalignment between the first and second portions.

In the above antenna device, the through hole of the magnetic material may have a shape in which the opening width narrows as it moves away from the substrate. This can prevent deterioration of the antenna characteristics.

An IC card according to one embodiment of the present disclosure includes any one of the antenna devices described above, a metal plate having a through hole, and an IC module disposed in the through hole of the metal plate, and the metal plate and the antenna device are stacked such that the through hole of the metal plate and the through hole of the magnetic body overlap, and the magnetic body is sandwiched between the substrate and the metal plate. This makes it possible to couple the second winding portion of the coil pattern to the IC module.

Reference Signs List 1, 1A to 1D Antenna device 3, 3A to 3D IC card 3a Top surface 3b of IC card Back surface 6 of IC card Card reader 10 Plastic plate 20 Base material 21 First main surface 22 Second main surface 23 Through hole 30 Magnetic body 31 Through hole 40 Metal plate 41 Through hole 50 IC module 51 Module substrate 52 IC chip 53 Coupling coil 54 Protective resin 61, 62 Adhesive layer 70 Insulating layer 110 First winding portion 110a Opening 120 Second winding portion 121 First portion 122 Second portion 121a, 122a Innermost turns 131 to 134 Capacitor pattern 140 Connection patterns 151 to 155 Via conductor C Capacitor CP Coil pattern E Terminal electrode

Claims (10)

a substrate having first and second opposed major surfaces;
a magnetic body covering the second main surface of the base material and having a through hole;
a coil pattern provided on the first and second main surfaces of the base material so as to overlap the magnetic body when viewed in a thickness direction of the base material,
the coil pattern includes a first winding portion provided on the first or second principal surface and a second winding portion disposed within an opening of the first winding portion as viewed from the thickness direction,
the second winding portion includes a first portion provided on the first main surface and winding around the periphery of the through hole of the magnetic material, and a second portion provided on the second main surface and winding around the periphery of the through hole of the magnetic material. The antenna device according to claim 1, wherein the second portion of the second winding portion has a bottom surface in contact with the second main surface of the substrate, a top surface opposite the bottom surface, and a side surface connecting the bottom surface and the top surface, and at least a portion of the top surface and the side surface are embedded in the magnetic material so that at least a portion of the top surface and the side surface are covered with the magnetic material. the substrate has a through hole overlapping with a through hole of the magnetic body,
The antenna device according to claim 2 , wherein an inner circumferential surface of the through hole of the magnetic body and an inner circumferential surface of the through hole of the base material form the same plane when viewed from the thickness direction. The antenna device according to claim 3, wherein the inner circumferential surface of the innermost turn of the first or second part of the second winding portion forms the same plane as the inner circumferential surfaces of the through hole of the magnetic body and the through hole of the base material when viewed from the thickness direction. The antenna device according to claim 2, further comprising an insulating layer located between the second portion of the second winding and the magnetic material. The antenna device according to claim 5, wherein the insulating layer is thicker between the turns of the second portion than between the second portion of the second winding and the magnetic body. The antenna device according to claim 1, wherein the number of turns in the second portion of the second winding section is less than the number of turns in the first portion of the second winding section. The antenna device according to claim 7, wherein the second portion of the second winding part has a pattern width wider than the first portion of the second winding part, and one turn constituting the second portion of the second winding part overlaps with multiple turns constituting the first portion of the second winding part. The antenna device according to claim 1, wherein the through hole of the magnetic body has a shape in which the opening width becomes narrower as it moves away from the substrate. An antenna device according to any one of claims 1 to 9,
A metal plate having a through hole;
an IC module disposed in the through hole of the metal plate;
an IC card, wherein the metal plate and the antenna device are stacked such that a through hole of the metal plate and a through hole of the magnetic body overlap, and the magnetic body is sandwiched between the base material and the metal plate;

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