JP2024104323A - Dual Interface IC Card - Google Patents

Abstract

[Problem] To provide a dual interface IC card in which a first coupling coil on the IC module side and a second coupling coil on the card base side are electromagnetically coupled well, and disconnection of the second coupling coil is suppressed even when the arrangement of the second coupling coil or the position of the recess is changed. [Solution] An IC card 1 includes an IC module 7 having a substrate, an external connection terminal 71, an IC chip, and a first coupling coil 110, a card base 2, a second coupling coil 120 and an external communication antenna 80 arranged at a distance from and facing the first coupling coil 110. The IC module is arranged in the recess so that the external connection terminal 71 is exposed. The recess is composed of a first recess for mounting the substrate, and a second recess smaller than the first recess for housing the IC chip 7. The IC card further includes a capacitance section 121 arranged at a distance from and facing the second coupling coil in the thickness direction inside the innermost circumference of the second coupling coil, and the second coupling coil, the capacitance section, and the external communication antenna form a closed circuit. [Selected Figure] Figure 1

Description

The present invention relates to a dual interface IC card capable of contact and non-contact communication with an external device.

Conventionally, IC cards include contact IC cards that input and output electrical signals through an external connection terminal on the surface of the card, and contactless IC cards that input and output electrical signals by electromagnetic induction or the like via an antenna. In addition to these, contact and contactless compatible IC cards, that is, dual interface IC cards, are also used, which can realize both the functions of a contact IC card and a contactless IC card with a single IC chip on the card. In particular, dual interface IC cards can be used as contact IC cards that are effective in preventing external leakage of input and output data during financial settlements, and as highly convenient contactless IC cards that exchange data in close proximity when entering and leaving a room or at a ticket gate at a station. For this reason, dual interface IC cards are also becoming more and more popular on the market.

Now, dual interface IC cards are manufactured as follows. First, as described in Patent Document 1, a card substrate containing one or more core sheets is formed, and an area in which an IC module is to be embedded is cut from the surface of the card substrate. Then, the IC module is embedded in the area in which it is to be embedded. Here, a conductor is arranged in one of the one or more core sheets, and the conductor forms a wound antenna part for providing the contactless communication function, and a contact terminal part that is in electrical contact with a terminal of the IC module, and the contact terminal part is arranged, for example, in a meandering shape.

Here, in Patent Document 1, when cutting the area to embed the IC module, a contact opening is provided in a part of the first recess for placing the outer periphery of the IC module, which is deeper than the first recess, so that the contact terminal of the winding antenna is exposed only at the contact opening. For this reason, the contact opening is filled with a liquid conductive adhesive to electrically connect the terminal of the IC module and the contact terminal. In this manner, in this manufacturing method, the IC module and the winding antenna are electrically connected via the conductive paste, so that the reliability of the electrical connection between the IC module and the winding antenna may vary depending on the conditions of the degree of exposure of the contact terminal of the winding antenna and the conditions of applying the conductive paste.

On the other hand, Patent Document 2 describes a communication medium including an IC module including an IC chip including a non-contact communication unit with a communication terminal and a contact communication unit, and a first coupling coil connected to the communication terminal. The communication medium further includes a second coupling coil arranged outside the first coupling coil so as to be capable of electromagnetic coupling with the first coupling coil and having an inductance smaller than that of the first coupling coil, and an antenna connected in series with the second coupling coil, and a base on which the IC module is mounted. With this configuration, the communication medium can electrically connect the IC module and the wound antenna by electromagnetic coupling between the first coupling coil and the second coupling coil without using a conductive paste. As a result, a highly reliable dual interface IC card can be provided with a reduced risk of breakage due to external force loads such as bending and environmental loads.

When manufacturing such a dual interface IC card, it is necessary to form a recess in the card base for housing the IC module by cutting or other processes. However, in order to obtain good electromagnetic coupling with the first coupling coil on the IC module side, it is necessary to provide a second coupling coil in a position close to the recess in the card base. However, slight deviations in the arrangement of the second coupling coil or the cutting position can cause the second coupling coil to break, which can prevent normal contactless communication.

JP 2019-219732 A JP 2016-12255 A

The present disclosure has been made in consideration of these circumstances, and aims to provide a dual interface IC card that can achieve good electromagnetic coupling between the first coupling coil on the IC module side and the second coupling coil on the card base side, and can prevent breakage of the second coupling coil due to variations in the arrangement of the second coupling coil or the position of the recess.

The first configuration of the dual interface IC card capable of contact and non-contact communication with an external device according to this embodiment includes an IC module having a substrate, an external connection terminal formed on one side of the substrate, an IC chip disposed on the other side, and a first coupling coil electrically connected to the IC chip to form a closed circuit; a card base; a second coupling coil disposed inside the card base and spaced apart from and facing the first coupling coil, and an external communication antenna connected in series to the second coupling coil; the IC module is disposed in a recess provided in the card base so that its external connection terminal is exposed, and the recess is composed of a first recess in which the substrate is mounted, and a second recess in which the IC chip is housed and which is smaller than the first recess in a plan view of the card base; and a capacitance section composed of conductive elements disposed apart from and facing each other in the thickness direction inside the innermost circumference of the second coupling coil in the plan view, and the second coupling coil, the capacitance section, and the external communication antenna form a closed circuit.

In addition, a second configuration of a dual interface IC card according to another embodiment of the present invention may further include an additional element formed by heating on the surface of the card base on which the external connection terminal is exposed, and the second coupling coil may be positioned 1.0 mm or more away from the additional element in the plan view in the first configuration described above.

In addition, a third configuration of the dual interface IC card according to another embodiment of the present invention may be such that, in the plan view, the second coupling coil is positioned 2.0 mm or more and 5.0 mm or less away from the second recess toward the outside, and the second coupling coil is positioned 0.0 mm or more and 6.5 mm or less away from the first recess.

In addition, a fourth configuration of the dual interface IC card according to another embodiment of the present invention relates to the first or second configuration described above, and when, in the plan view, the innermost portion of the first coupling coil is included between the innermost and outermost portions of the second coupling coil, and the distance by which the innermost portion of the second coupling coil protrudes inward from the innermost portion of the first coupling coil is defined as a first distance, and the distance by which the outermost portion of the second coupling coil protrudes outward from the outermost portion of the first coupling coil is defined as a second distance, the first distance may be 0.5 mm or more and 3.5 mm or less, and the second distance may be -1.0 mm or more and 1.0 mm or less.

In addition, a fifth configuration of a dual interface IC card according to another embodiment of the present invention relates to the first to fourth configurations described above, and in the plan view, the inductance of the second coupling coil may be greater than the inductance of the first coupling coil.

According to this embodiment, it is possible to provide a dual interface IC card that can effectively electromagnetically couple the first coupling coil on the IC module side with the second coupling coil on the card base side, and can prevent the second coupling coil from breaking due to variations in the arrangement of the second coupling coil or the position of the recess.

1 is a plan view illustrating a structure of a dual interface IC card according to a first embodiment. FIG. 2 is a diagram illustrating a configuration of an IC module. 2 is a cross-sectional view showing a cross section taken along line AA in FIG. FIG. 2 is a schematic circuit diagram showing an equivalent circuit of a dual interface IC card. FIG. 11 is a plan view corresponding to FIG. 1 and explaining the structure of a dual interface IC card according to a second embodiment. 5(a) is a cross-sectional view taken along line BB in FIG. 5(a) and corresponds to FIG. 3. FIG.

An example of a dual interface IC card according to the present disclosure will be described below with reference to the drawings. However, the dual interface IC card according to the present disclosure is not limited to the embodiment and examples described below.

The figures shown below are schematic. Therefore, the size and shape of each part are appropriately exaggerated to make it easier to understand. Hatching showing the cross section of a member is also omitted in each figure. The numerical values such as dimensions of each member and the names of materials described in this specification are examples of embodiments, and are not limited to these, and may be selected and used as appropriate. In this specification, terms that specify shapes or geometric conditions, such as parallel, orthogonal, and perpendicular, are intended to include substantially the same state in addition to their strict meaning.

1. First embodiment An example of a first embodiment of a dual interface IC card of the present disclosure will be described. Here, for convenience of description, an XYZ coordinate system is set for the IC card 1. The IC card 1 is a dual interface IC card. As shown in FIG. 1(a) and FIG. 3, the Z axis is taken in the normal direction of the main surface of the IC card 1. The direction from the main surface on the side where the external connection terminals 71 of the IC module 7 are not arranged to the main surface on the side where the external connection terminals 71 are arranged is defined as the +Z direction or the upward direction in the thickness direction, and the opposite direction is defined as the -Z direction or the downward direction in the thickness direction.

When IC card 1 is viewed from the +Z direction, the straight line perpendicular to both short sides of IC card 1 and the Z axis is defined as the X axis, the direction from one short side closer to external connection terminal 71 toward the other short side is defined as the +X direction or rightward direction, and the opposite direction is defined as the -X direction or leftward direction. Furthermore, the axis perpendicular to the X and Z axes is defined as the Y axis, the direction from one long side farther from external connection terminal 71 toward the other long side is defined as the +Y direction or upward direction, and the opposite direction is defined as the -Y direction or downward direction.

Here, FIG. 1(a) is a plan view of IC card 1 seen from the +Z direction, and FIG. 1(b) is a diagram of only the core layer 5 of IC card 1 in FIG. 1(a) that explains the configuration of antenna 8 including second coupling coil 120 and external communication antenna 80. FIG. 1(b) shows only the elements of antenna 8 arranged on the surface of core layer 5 on the +Z direction side. Meanwhile, FIG. 1(c) is a diagram of only the core layer 5, but shows only the elements of antenna 8 arranged on the surface of core layer 5 on the -Z direction side. Also, FIG. 1(d) is a diagram of IC card 1 in FIG. 1(a) that shows only IC module 7.

Figure 2(a) is an enlarged view showing the configuration of IC module 7 shown in Figure 1(d), and Figure 2(b) is a view of IC module 7 in Figure 2(a) seen from the opposite side, i.e., rotated 180° about the Y axis. Also, Figure 3 is a cross-sectional view of IC card 1 in Figure 1(a) taken along line A-A along the X axis near IC module 7, seen from the -Y direction side. Figure 4 is a diagram showing a schematic equivalent circuit of IC card 1.

As shown in FIG. 1(a), IC card 1 has the form of a generally rectangular thin plate with rounded corners in a plan view from the +Z direction side. Also, on the surface on the +Z direction side of the dual interface IC card, IC module 7 including external connection terminal 71 is disposed slightly to the upper left of the center, that is, closer to the -X direction and closer to the +Y direction than the center. As shown in FIG. 1(a) and FIG. 3, IC module 7 is embedded in recess 9 formed in card base 2, and disposed so that the surface on the +Z direction side of external connection terminal 71 is approximately flush with the surface on the +Z direction side of card base 2. Such a form of IC card 1 complies with ISO/IEC 7816, the international standard for IC cards.

As shown in FIG. 3, the card base 2 constituting the card body of the IC card 1 is, in order as viewed from the -Z direction, an oversheet layer 6, a core layer 5, a core layer 4, and an oversheet layer 3 laminated and integrated together. Typically, the oversheet layers 6 and 3 are transparent substrates, and the core layers 5 and 4 are white substrates, but this is not limited thereto. In addition, the antenna wire 83 constituting the antenna 8 is disposed between the core layers 5 and 4 so as to be sandwiched between them.

As shown in FIG. 1(b), the antenna 8 formed by this antenna wire 83 includes an external communication antenna 80 wound in a substantially rectangular loop shape along the outer periphery of the card base 2, a second coupling coil 120 wound in a substantially rectangular loop shape with a smaller diameter than the external communication antenna 80, and a capacitance section 121. The external communication antenna 80 and the second coupling coil 120 are connected to each other in series.

Here, the external communication antenna 80 and the second coupling coil 120 are arranged on one surface of the core layer 5 in the card base 2, i.e., the surface on the +Z direction side, as shown in FIG. 1(b). A flat conductive element 121a that is approximately C-shaped or U-shaped in a planar view is connected to the inner tip of the antenna wire 83 that forms the loop of the second coupling coil 120. The inner tip of the antenna wire 83 that forms the loop of the external communication antenna 80 is connected to the back side of the core layer 5 via the front-back conductive part 84.

That is, as shown in FIG. 1(c), the other surface of the core layer 5, i.e., the surface on the -Z direction side, is connected to a flat conductive element 121b having a shape similar to that of the conductive element 121a described above, via a lead wire 85 at a predetermined distance from the front-back conductive portion 84. The lead wire 85 may be, for example, an antenna wire 83. The front-back conductive portion 84 may be, for example, a through hole formed in the core layer 5, the side of which is subjected to a conductive treatment such as metal plating. The conductive elements 121a and 121b are arranged opposite each other in the thickness direction of the card base 2, separated by the thickness of the core layer 5, as shown in FIG. 3, to form a capacitance portion 121 that constitutes a capacitor.

In this way, the antenna 8 is formed by connecting in series the external communication antenna 80 and the second coupling coil 120 formed on one side of the core layer 5, and the capacitance section 121 composed of conductive elements 121a and 121b arranged to face each other and spaced apart in the thickness direction of the card base 2, forming one closed circuit. The conductive elements 121a and 121b are formed across the front and back surfaces of the core layer 5. The capacitance section 121 is provided inside the innermost circumference of the second coupling coil 120. Therefore, even if a part of the capacitance section 121 is cut during the cutting process to form the recess 9, it is possible to prevent the closed circuit of the antenna 8 from being immediately disconnected. Since the capacitance section 121 has a certain width as the conductive elements 121a and 121b, it will not lose its function as the capacitance section 121 unless they are completely cut and disappear, and good communication of the second coupling coil 120, etc. can be ensured.

On the other hand, as shown in Figures 1(a), 1(d), 2(a) and 2(b), the IC module 7 comprises a flat substrate 72 and an external connection terminal 71 formed on the surface of the substrate 72 facing the +Z direction. The IC module 7 also comprises an IC chip 74a arranged on the surface of the substrate 72 facing the -Z direction, and a first coupling coil 110 wound in a substantially rectangular loop and electrically connected to the IC chip 74a so as to form a closed circuit. The second coupling coil 120 arranged inside the card base 2 together with the external communication antenna 80 is arranged facing and spaced apart from the first coupling coil 110. If the schematic circuit configuration of the IC card 1 is replaced with an equivalent circuit, it will look like, for example, Figure 4.

When electromagnetic waves of a specific wavelength are received from an external device by the external communication antenna 80, which is coil L3, a current due to the induced electromotive force flows in the closed circuit formed by coils L2, L3 and capacitance C2, and a magnetic field is generated in the second coupling coil 120, which is coil L2. A similar magnetic field is generated in the first coupling coil 110, which is coil L1, which is disposed opposite to this. As a result, a current due to the induced electromotive force flows in the closed circuit formed by capacitance C1, resistance R1 and coil L1 of the IC chip 74a, and the power required for the operation of the IC chip 74a is supplied.

Here, coil L2, coil L3, and capacitance C2 in the equivalent circuit of FIG. 4 respectively represent the coil and capacitance formed by the second coupling coil 120, external communication antenna 80, and capacitance section 121 formed on the card base 2. In the closed circuit formed by coil L2, which is the second coupling coil 120, L3, which is the external communication antenna 80, and capacitance C2, which is the capacitance section 121, the communication strength is maximized at a resonant frequency determined by a predetermined inductance and capacitance. For example, when contactless communication at 13.56 MHz is assumed, capacitance C2, which is the capacitance section 121, can be set so that the resonant frequency of the closed circuit is 13.56 MHz.

In addition, the electromagnetic waves of a specific wavelength that the external communication antenna 80 receives from an external device are input as signals that comply with standards for non-contact IC cards and communication media, as described below, so ultimately, it becomes possible not only to supply power to the IC chip 74a, but also to input specific data. Conversely, it is also possible to transmit specific data from the IC chip 74a to an external device via the external communication antenna 80.

In this way, the first coupling coil 110 provided on the IC module 7 side and the second coupling coil 120 provided on the card base 2 side, spaced apart and facing each other, are electromagnetically coupled to each other, thereby enabling the necessary power supply and data transmission and reception. This has the following advantages over a method in which the IC module 7 and the external communication antenna 80 are physically connected via a conductive adhesive such as conductive paste. That is, it is possible to prevent the reliability of the electrical connection between the IC module 7 and the external communication antenna 80 from decreasing due to external force loads such as bending or twisting of the IC card 1, or environmental loads such as temperature and humidity.

In the IC card 1 of this embodiment, the IC module 7 is disposed in a recess 9 provided in the card base 2 so that its external connection terminal 71 is exposed on the surface in the +Z direction, as shown in FIG. 3. The recess 9 further comprises a first recess 91 in which the substrate 72 is mounted, and a second recess 92 in which the IC chip body 74 including the IC chip 74a is housed and which is smaller than the first recess 91 in a plan view along the Z axis direction of the card base 2.

Here, in the plan view, the second coupling coil 120 has a capacitance section 121 composed of conductive elements 121a and 121b arranged opposite each other and spaced apart in the thickness direction, inside the innermost circumference. As a result, the antenna 8 composed of the second coupling coil 120, the capacitance section 121, and the external communication antenna 80 forms a single closed circuit.

In general, when forming the recess 9 for embedding the IC module 7 in the card base 2 by cutting or the like, if the arrangement or cutting position of the second coupling coil 120 is deviated from the design value, the following problems may occur. That is, cutting the recess 9 may damage the second coupling coil 120 or break the antenna wire 83, making it impossible to perform good non-contact communication. However, in the IC card 1 of this embodiment, the capacitance section 121 is provided inside the innermost circumference of the second coupling coil 120, and even if a part of the capacitance section 121 is cut during cutting, the closed circuit of the antenna 8 is not immediately broken. Since the capacitance section 121 has a certain width as the conductive elements 121a and 121b, it does not lose its function as the capacitance section 121 unless these are completely cut and disappear, and communication of the second coupling coil 120 and the like can be performed normally.

Furthermore, if part of the capacitive portion 121 is cut during cutting, depending on the extent of the cutting, a change in capacitance occurs as the area of the conductive elements 121a and 121b is reduced, and the resonant frequency, etc. changes. As a result, by monitoring the change in the resonant frequency of the manufactured IC card 1, it is possible to estimate the degree to which the arrangement of the second coupling coil 120 and the cutting position deviate from the design values, making it possible to inspect the manufacturing conditions and the stability of product quality while preventing defects such as breakage of the antenna 8.

As described above, in this embodiment, it is possible to provide a dual interface IC card that can effectively electromagnetically couple the first coupling coil on the IC module side with the second coupling coil on the card base side, and can suppress breakage of the second coupling coil due to variations in the arrangement of the second coupling coil or the position of the recess formation. The configuration of the IC card 1 of this embodiment and the manufacturing method thereof are described in detail below.

(a) Card Base The card base 2 refers to the card body excluding the IC module 7 constituting the IC card 1. As described above, the card base 2 typically has a configuration in which the oversheet layer 6, the core layer 5, the core layer 4, and the oversheet layer 3 are laminated in this order from one end on the -Z direction side in the thickness direction. In addition, between the core layer 5 and the core layer 4, an antenna 8 formed of a coated conductor wire or the like is arranged, including an external communication antenna 80 wound in a substantially rectangular loop shape along the outer periphery of the card, and a second coupling coil 120 wound in a substantially rectangular loop shape that is one size smaller than the external communication antenna 80. The antenna 8 also includes a capacitance section 121. The card base 2 may refer to both the card before the recess 9 is formed and the card after the recess 9 is formed, and may refer to both the card without the antenna 8 and the card including the antenna 8.

However, the layer structure of the card base 2 is not limited to this, and may be a three-layer structure of an oversheet layer, a core layer, and an oversheet layer, a two-layer structure of a core layer and a core layer, or a five-layer structure of an oversheet layer, a core layer, a pair of antenna holding layers sandwiching the antenna, a core layer, and an oversheet layer. In addition, printing or embedding of a magnetic stripe may be performed on the surface of the oversheet layer 3 or 6 of the card base 2 opposite the core layer 4 or 5, and printing may be performed on the surface of the core layer 4 or 5 adjacent to the oversheet layer 3 or 6.

As shown in FIG. 1(a) and FIG. 3, the IC card 1 of this embodiment further includes an additional element 200 formed by printing, transfer, or the like on the surface of the +Z direction side of the card base 2, i.e., the surface on which the external connection terminal 71 is exposed. The additional element 200 includes, for example, a thermal head that is used to thermally transfer dye-based ink from an ink ribbon onto the surface of the card base 2, by thermal transfer, sublimation transfer, inkjet printing, or the like, to form patterns such as letters, designs, and facial photographs. It also includes a hologram foil or metal foil formed on a continuous film that is thermally transferred onto the surface of the card base 2. The additional element 200 includes a printed element having letters, symbols, facial photographs, etc., particularly indicating personal information or unique numbers, and a security element such as a hologram, printed or transferred onto the surface of either the +Z direction side or the -Z direction side of the card base 2.

The thickness of the card base 2 is preferably 0.76 mm or more and 0.84 mm or less in terms of compliance with standards such as ISO/IEC 7816, but may be outside this range.

(i) Core layer As the core layers 4 and 5, various types of white or colored plastic sheets can be widely used, and the following single films or composite films thereof can be used. For example, polyethylene terephthalate (PET), PET-G (terephthalic acid-cyclohexanedimethanol-ethylene glycol copolymer), polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polycarbonate, polyamide, polyimide, cellulose diacetate, cellulose triacetate, polystyrene, ABS, polyacrylic acid ester, polypropylene, polyethylene, polyurethane, etc. The thickness of the core sheet can be appropriately selected taking into account the overall thickness of the card, and can be, for example, about 0.25 mm or more and 0.38 mm or less. As described later, it is necessary to arrange the antenna 8, excluding the capacitance part 121, on the surface of either the core layer 4 or 5 so that it is sandwiched between the two core layers.

(ii) Over-sheet layer The over-sheet layers 3 and 6 are usually made of the same material as the core layer, and are often made of a transparent material having a thickness of about 0.05 mm or more and 0.10 mm or less. From the viewpoint of preventing curling when the laminate of the core layer and the over-sheet layer is integrated by heat pressing or the like, it is preferable that the over-sheet layers 3 and 6 have the same thickness, but they do not necessarily have to be the same.

The material of the oversheet layer may be any material that is adhesive when heated, but even if the oversheet layer itself does not have adhesive properties when heated, the core layer and the oversheet layer can be integrated by forming an additional layer of a known adhesive that generates adhesive strength when heated between them. When the IC card 1 is used as a magnetic card, a magnetic stripe may be embedded in advance by thermal transfer or the like on the main surface side opposite the core layers 4 and 5 of either or both of the oversheet layers 3 and 6. As mentioned above, the oversheet layer may have a coloring layer that turns black or another chromatic color when irradiated with laser light of a specified wavelength.

(iii) Antenna Sheet In this embodiment, as described later, an antenna 8 is formed on one surface of the core layer 5, the antenna 8 including an external communication antenna 80 wound in a substantially rectangular loop shape along the outer periphery of the card, and a second coupling coil 120 wound in a substantially rectangular loop shape that is one size smaller than the external communication antenna 80. The formation of the antenna 8 on the core layer 5 is performed by applying a predetermined heat and pressure to the antenna wire 83, and embedding the antenna wire 83 in the core layer 5 while melting the core layer 5 and the coating of the antenna wire 83. However, at the point where the antenna wires 83 cross each other, one of the antenna wires 83 is not embedded in the core layer 5.

Before embedding the antenna wire 83 in the core layer 5, the front-back conductive portion 84, the lead wire 85, and the flat conductive elements 121a and 121b constituting the capacitance portion 121 are formed at predetermined positions on the core layer 5 at opposing positions on the front and back of the core layer 5. As described above, the front-back conductive portion 84 may be a through-hole formed in the core layer 5, with the side of the through-hole subjected to a conductive treatment such as metal plating. The lead wire 85 and the conductive elements 121a and 121b may also be formed by a printing method using conductive ink. In this embodiment, the external communication antenna 80 and the second coupling coil 120 are drawn and embedded on one side of the core layer 5 in a so-called one-stroke drawing, with one antenna wire 83 drawn around, starting from the front-back conductive portion 84 and ending at the conductive element 121a. The connection of the antenna wire 83 to the conductive element 121a may be by welding via solder or the like, or by bonding via a conductive adhesive or the like.

As a result, the front-back conductive portion 84, external communication antenna 80, second coupling coil 120, and conductive element 121a formed on one side of the core layer 5 are electrically connected to the conductive element 121b, lead wire 85, and front-back conductive portion 84 formed on the other side. The conductive elements 121a and 121b form the capacitance portion 121, and these antennas 8 form a closed circuit.

Such an intermediate product in which the antenna 8 is embedded in the core layer 5 is sometimes called an antenna sheet 12. The antenna sheet 12 can be distributed on the market as a component for manufacturing IC cards 1 by itself, or a commercial model may exist in which sheet material such as the core layer 5 is supplied to a processor who processes it into an antenna sheet 12 and delivers it to the supplier.

The details of the method for forming the antenna sheet 12 will be described later, but the outline is as follows. First, as described above, a coated conductor covered with an insulating material is embedded in the surface of the core layer 5 on which the front-back conductive portion 84, the lead wire 85, and the capacitance portion 121 have been formed in advance, starting from the front-back conductive portion 84 and ending at the conductive element 121a, using a winding forming machine. That is, while applying a predetermined heat pressure to the core layer 5, the antenna supply head is drawn into two large and small loop shapes as shown in FIG. 1 (b). Then, the antenna wire 83 supplied from the antenna supply head is embedded in the core layer 5 in sequence so as to form the external communication antenna 80 and the second coupling coil 120. After that, the starting point and the ending point of the antenna wire 83 are connected to complete the embedding. In this way, the core layer 5 (antenna sheet 12) on which the antenna 8 is formed is obtained.

(iv) Antenna The antenna 8 formed on the core layer 5 has an antenna wire 83 that is connected at its start and end to form a closed circuit. The antenna 8 includes an external communication antenna 80 wound in a substantially rectangular loop shape along the outer periphery of the card, and a second coupling coil 120 wound in a substantially rectangular loop shape that is one size smaller than the external communication antenna 80, and the external communication antenna 80 and the second coupling coil 120 are connected in series to each other. The second coupling coil 120 of the antenna 8 is spaced apart from and faces the first coupling coil 110 formed on the IC module 7 side. The first coupling coil 110 and the second coupling coil 120 are electromagnetically coupled to each other, so that the IC chip 74a of the IC module 7 and the external communication antenna 80 form a communication circuit for non-contact communication.

As shown in FIG. 3, in a plan view along the Z axis, the second coupling coil 120 has a capacitance section 121 composed of conductive elements 121a and 121b arranged opposite each other and spaced apart from each other in the thickness direction of the core layer 5, located inside the innermost circumference. Illustratively, the conductive elements 121a and 121b are provided on the front and back surfaces of the core layer 5, respectively. Through the front and back conductive section 84, the second coupling coil 120, the capacitance section 121, and the external communication antenna 80 form a communication circuit for non-contact communication that is a closed circuit. The capacitance of the capacitance section 121 is determined in accordance with the inductance of the second coupling coil 120 and the external communication antenna 80 so that the communication circuit can communicate at a predetermined resonant frequency.

The communication circuit may perform close-proximity communication using, for example, the 13.56 MHz HF frequency band defined by ISO/IEC 18092, ISO/IEC 144443, etc. Alternatively, it may perform communication using other frequencies, such as the 920 MHz UHF frequency band, the 125 KHz LF frequency band, or the 2.45 GHz microwave frequency band. In this embodiment, it is assumed that close-proximity communication is performed using the 13.56 MHz HF frequency band, and the first coupling coil 110, the second coupling coil 120, and the external communication antenna 80 all have a loop coil shape.

When IC card 1 is held over an external device such as a reader/writer, an electromotive force or current is generated in the communication circuit by the magnetic field generated by the reader/writer, and power is supplied to IC chip 74a. This enables IC chip 74a to be driven, enabling contactless transmission and reception of information with the reader/writer, and reading and rewriting information from and to the memory.

The antenna wire 83 constituting the antenna 8 is typically formed of a coated conductor wire in which the periphery of a copper wire is coated with an insulating material. In addition to this, it is also possible to select copper alloy wires such as Cu-Ni, Cu-Cr, Cu-Zn, Cu-Sn, and Cu-Be, or various metal wires and metal alloy wires such as iron, stainless steel, and aluminum. By using coated conductor wires, the IC card 1 can be manufactured more inexpensively than, for example, a copper foil etching method.

There are no particular limitations on the diameter of the antenna wire 83, so long as the characteristics as a non-contact communication circuit can be ensured, but it can be, for example, 0.03 mm or more and 0.30 mm or less, and preferably 0.05 mm or more and 0.15 mm or less. By keeping it in the latter range, durability against heat pressure due to embedding processing and external forces due to cutting processing can be improved, and good communication characteristics can be ensured.

The self-inductance of the second coupling coil 120 is preferably 0.5 μH or more and 10 μH or less. The self-inductance of the second coupling coil 120 is preferably greater than the self-inductance of the first coupling coil 110 described below. This reduces the degree of fluctuation in the induced electromotive force on the first coupling coil 110 side relative to fluctuations in the induced electromotive force on the second coupling coil 120 side, thereby stabilizing the power supply to the IC chip 74a.

The conductive elements 121a and 121b constituting the capacitance section 121 can be formed into a flat pattern, for example, by a printing method using conductive ink. Other methods include attaching a flat metal foil or metal plate, or forming a metal vapor deposition film by sputtering. Furthermore, the antenna wires 83 themselves can be densely arranged at opposing positions on the front and back surfaces of the core layer 5 so as to be approximately flat, and this can be used as the capacitance section 121. In this way, the capacitance section 121 can be formed only by forming the antenna wires 83 without using a separate member, making it easy to reduce the number of types of members and the number of work processes. When the antenna wires 83 themselves are arranged to be approximately flat to form the capacitance section 121, it is preferable to set the arrangement interval of the antenna wires 83 to 0.5 mm or less. This makes it possible to ensure the required capacitance while reducing the area of the flat plate.

The conductive elements 121a and 121b constituting the capacitance section 121 are flat parts that are approximately C-shaped, U-shaped, or U-shaped in a planar view along the Z axis. However, the shape of the conductive elements 121a and 121b is not limited to this, and may be linear, approximately L-shaped, approximately arc-shaped, or may have an approximately rectangular outline. The area and width can be set arbitrarily within the range in which the required resonant frequency can be adjusted, but from the viewpoint of preventing damage to the second coupling coil 120 during cutting, it is preferable that they are 0.5 mm or more and 2.5 mm or less.

The front-back conductive portion 84 can be, for example, a through-hole formed in the core layer 5, with the side of the through-hole subjected to a conductive treatment such as metal plating. As another method, a hollow or solid metal member may be arranged to penetrate the core layer 5 so as to straddle the front and back. The lead wire 85 may be formed of conductive ink or the like, like the conductive elements 121a and 121b, or may be formed of the antenna wire 83.

(b) IC Module Next, each part of the main components of the IC module 7 will be described mainly with reference to Figures 1(a), 2(a), 2(b) and 3. The IC module 7 is embedded in a recess 9 formed in the card base 2 so that its external connection terminal 71 is exposed on the surface of the card base 2 on the +Z direction side. The IC module 7 has a substrate 72, an external connection terminal 71 formed on the surface of the substrate 72 on the +Z direction side, an IC chip body 74 including an IC chip 74a arranged on the surface on the -Z direction side, and a first coupling coil 110 electrically connected to the IC chip 74a to form a closed circuit.

The IC chip 74a and the first coupling coil 110 form a closed circuit, which forms a communication circuit for non-contact communication. On the other hand, contact communication can also be performed with a contact type reader/writer or the like through the external connection terminal 71 provided on the IC module 7.

The substrate 72 is made by attaching copper foil to the front and back of a flexible insulating resin film such as glass epoxy resin or polyimide resin with an adhesive, and leaving the copper foil attached to the front and back of the resin film to form a predetermined pattern. Specifically, a photosensitive material is applied, a film plate with a predetermined pattern is placed, exposed, and the non-photosensitive portion is etched away in order to form an external connection terminal 71 on one copper foil surface of the resin film and a first coupling coil 110 and a lead portion 77 on the other copper foil surface. This forms the substrate 72 with some of the copper foil remaining in a predetermined pattern on the front and back of the resin film. In addition, the substrate 72 is provided in advance with a plurality of bonding holes 76, which are through holes for wire bonding to the external connection terminals 71.

2(a), the external connection terminal 71 is divided into sections of the external terminal as defined by the ISO/IEC 7816-2 standard. As shown in FIG. 2(b), each of these sections and the pads 74p of the IC chip 74a are connected by wires 75 such as gold wires through the above-mentioned bonding holes 76 provided in the substrate 72. Also, the start and end points of the first coupling coil are provided with lead portions 77, which are conductive parts. For example, in FIG. 2(b), the outermost end of the first coupling coil 110 is connected to the horizontally elongated, approximately rectangular lead portion 77. Also, the innermost end of the first coupling coil 110 is connected to the approximately circular lead portion 77. The first coupling coil 110 and these lead portions 77 may be formed integrally.

With this configuration, each pad 74p, which is the communication electrode of the IC chip 74a, is electrically connected to each terminal of the external connection terminal 71 and the start and end points of the first coupling coil 110. These bonding holes 76, parts of the lead portions 77, and the wires 75 are covered and protected by the molded portion 74b.

An IC chip body 74 is disposed on the surface of the substrate 72 opposite to the surface on which the external connection terminals 71 are formed. The IC chip body 74 is composed of an IC chip 74a bonded and fixed to the substrate 72 with an adhesive, bonding wires 75 for connection, and a molded part 74b which is a sealing resin for protecting these. The IC chip 74a includes a CPU for controlling the operation of both contact and non-contact communication, a storage device such as RAM, ROM, EEPROM, flash memory, and various circuits such as an interface circuit that decodes input signals and generates output signals for contact and non-contact communication, and a power generation circuit. Note that the various circuits may be provided as elements separate from the IC chip 74a.

The molded portion 74b is provided as a protruding portion that covers the IC chip 74a and the wires 75 to protect them from external force loads and environmental loads. UV-curable resin, thermosetting resin, or the like is used for the molded portion 74b.

In this embodiment, the IC module 7 is illustrated as being configured such that each section of the external connection terminal 71 and each pad 74p of the IC chip 74a are connected by wires 75 through bonding holes 76 provided in the substrate 72. The configuration of the IC module 7 is not limited to this, and the IC chip 74a may be mounted by a flip-chip method. In other words, the mounting surface of the IC chip 74a on the substrate 72 may be provided with multiple lead portions such as copper foil, and each pad 74p of the IC chip 74a mounted face-down may be configured to directly abut one end of the lead portion.

At this time, the other end of the lead portion is electrically connected to each section of the external connection terminal 71 via a through hole, or is electrically connected to the start point and end point of the first coupling coil 110. In this way, by electrically connecting the IC chip 74a to each section and the first coupling coil 110 without using wires 75, the area in which the first coupling coil 110 can be placed can be expanded toward the IC chip 74a.

The self-inductance of the first coupling coil 110 is preferably 0.1 μH or more and 8.0 μH or less. The self-inductance of the first coupling coil 110 is preferably smaller than the self-inductance of the second coupling coil 120 described above.

(c) Adhesive Layer After forming the recess 9 for embedding the IC module 7 in the card base 2 by cutting with an end mill or the like, the adhesive layer 11 for embedding and fixing the IC module 7 in the recess 9 will be described. As shown in Fig. 3, the adhesive layer 11 is a liquid or tape-like member that is disposed so as to be sandwiched between the core layer 5 at the portion where the antenna wire 83 is cut and exposed at the bottom surface 91a, and the substrate 72 of the IC module 7. The adhesive layer 11 may be applied or affixed in advance to the surface of the substrate 72 of the IC module 7 opposite to the external connection terminal 71, or may be applied or affixed on the bottom surface 91a after the recess 9 of the card base 2 has been cut.

A typical adhesive layer 11 may be applied or stuck to the entire back surface of the substrate 72 of the IC module 7 or to a portion of the recess 9 that corresponds to the first recess 91. For the adhesive layer 11, adhesives containing thermoplastic resins, such as vinyl chloride, vinyl acetate, and acrylic adhesives, hot melt adhesives, and rubber adhesives, can be selected. Also, adhesives containing thermosetting resins, such as polyester resin, phenolic resin, polyurethane resin, and epoxy resin adhesives, can be selected.

(c) Positional Relationship of the Recess, IC Module, First Coupling Coil, and Second Coupling Coil Next, a preferred positional relationship between the recess 9 and second coupling coil 120 formed in the card base 2 of the IC card 1, and the IC module 7 embedded in the recess 9 and its first coupling coil 110 will be described. As shown in Fig. 3, in a cross-sectional view of the IC card 1 seen from the -Y direction side, the distance between the innermost peripheries of the first coupling coil 110, i.e., the distance of the opening formed by the first coupling coil 110, is taken as DC. Also, the distance between the outermost peripheries of the first coupling coil 110, i.e., the distance of the maximum width of the first coupling coil 110, is taken as DB.

Similarly, the distance between the innermost parts of the second coupling coil 120, i.e., the distance of the opening formed by the second coupling coil 120, is DD, and the distance between the outermost parts of the second coupling coil 120, i.e., the distance of the maximum width of the second coupling coil 120, is DA. Also, the distance between the innermost parts of the capacitance part 121, i.e., the distance of the opening of the capacitance part 121, is DE. Also, the distance between the side surfaces of the second recess 92, i.e., the distance of the width of the second recess 92, is DF. Furthermore, the distance between the outer peripheral side surface of the first recess 91 and the outermost part of the second coupling coil 120, i.e., the distance away from the first recess 91 of the second coupling coil 120 to the outside is DG. Also, the distance between the outer peripheral side surface of the second recess 92 and the capacitance part 121 is DH.

On the other hand, the distance between the outermost part of the second coupling coil 120 and the end of the additional element 200, i.e., the separation distance between the second coupling coil 120 and the additional element 200, is defined as DI. Note that the distances DA, DB, DC, DD, DE, DF, DG, DH and DI all refer to the distances in a planar view along the Z-axis direction. Furthermore, the distances DA, DB, DC, DD, DE, DF, DG, DH and DI are not defined only for a cross section seen from the -Y direction side, but also apply to any cross section cut around an axis along the Z-axis.

Here, in a plan view along the Z axis, it is preferable that the capacitance section 121 is arranged at a distance of 0.5 mm or more and 2.5 mm or less outward from the second recess 92. In other words, it is preferable that DH is 0.5 mm or more and 2.5 mm or less, and it is even more preferable that DH is 0.75 mm or more and 2.0 mm or less. Under the former condition, even if the size or position of the second recess 92 varies to a certain extent or the position of the capacitance section 121 is shifted during cutting of the recess 9 into the card base 2, the risk of capacitance fluctuation due to cutting of the capacitance section 121 can be reduced while ensuring the arrangement area of the second coupling coil. Moreover, under the latter condition, the risk of capacitance fluctuation can be further reduced.

It is also preferable that the second coupling coil 120 is arranged so as to extend from the first recess 91 to the outside by 0.0 mm or more and 6.5 mm or less. In other words, it is preferable that DG is 0.0 mm or more and 6.5 mm or less, and more preferably 0.5 mm or more and 6.0 mm or more. The fact that the second coupling coil 120 is arranged so as to extend from the first recess 91 to the outside by 0.0 mm means that the outer edge of the second coupling coil 120 approximately coincides with the outer edge of the first recess 91. Under the former condition, even if the first coupling coil 110 is arranged up to the outermost periphery of the substrate 72, the arrangement of the second coupling coil in an unnecessary region is suppressed, and the risk of the first coupling coil 110 not overlapping the second coupling coil 120 and the coupling being weakened can be reduced. Under the latter condition, the risk of the first coupling coil 110 not overlapping the second coupling coil 120 and the coupling being weakened can be further reduced.

Generally, the range of variation in size and positional deviation of the first recess 91 and the second recess 92 when forming the recess 9 in the card base 2 is within approximately ±0.1 mm. Therefore, if DG and DH are within the above range, the capacitance variation due to cutting of the capacitance section 121 and the variation in the overlapping area between the first coupling coil 110 and the second coupling coil 120 can be suppressed as much as possible.

The surface of the card base 2 of the IC card 1 on which the external connection terminal 71 is exposed, i.e., the surface on the +Z direction side, may further include an additional element 200 formed by heating. In this case, in a plan view along the Z axis, it is preferable that the second coupling coil 120 is disposed at a distance of 1.0 mm or more from the additional element 200. In other words, it is preferable that DI is 1.0 mm or more. The additional element 200 is formed on the surface of the card base 2 using a printing or transfer means such as an inkjet printer, a thermal head, or a hot stamp. On the other hand, since the second coupling coil 120 is embedded inside the card base 2, unevenness corresponding to the antenna wire 83 appears on the surface of the card base 2 during lamination formation by heat pressing. In other words, unevenness appears on the surface of the card base 2 on the +Z direction side or the -Z direction side, or on both surfaces.

At this time, if the separation distance DI between the second coupling coil 120 and the additional element 200 is small, unevenness will occur on the surface of the card base 2 in the formation area of the additional element 200, and the formation of a good additional element 200 may be hindered due to blurring or missing print. Even if the additional element 200 can be formed, the unevenness on the surface of the card base 2 may cause distortion of the letters, symbols, photographs, etc. of the additional element 200, making it difficult to clearly view this information. Furthermore, if the additional element 200 is a hologram label or the like formed by thermal transfer, the unevenness on the surface of the card base 2 may cause poor adhesion.

However, in this embodiment, the second coupling coil 120 is positioned at a distance of 1.0 mm or more from the additional element 200, so that unevenness on the surface of the card base 2 caused by the second coupling coil 120 is suppressed. As a result, the additional element 200 can be formed well on the surface of the card base 2, and the letters, symbols, photographs, etc. of the additional element 200 can be clearly seen.

In addition, in a plan view along the Z axis, the innermost portion of the first coupling coil 110 is included between the innermost and outermost portions of the second coupling coil 120, and the distance by which the innermost portion of the second coupling coil 120 protrudes inward from the innermost portion of the first coupling coil 110 is defined as the first distance. In addition, the distance by which the outermost portion of the second coupling coil 120 protrudes outward from the outermost portion of the first coupling coil 110 is defined as the second distance. In this case, it is preferable that the first distance is 0.5 mm or more and 3.5 mm or less, and the second distance is -1.0 mm or more and 1.0 mm or less. When the second distance is negative, it means that the outermost portion of the first coupling coil 110 protrudes inward from the outermost portion of the second coupling coil 120 by the distance of the absolute value of the value of the second distance. Furthermore, it is even more preferable that the innermost and outermost parts of the first coupling coil 110 are included between the innermost and outermost parts of the second coupling coil 120, the first distance is 0.5 mm or more and 3.5 mm or less, and the second distance is 0.1 mm or more and 1.0 mm or less. This is because, even if the first coupling coil 110 and the second coupling coil 120 are misaligned relative to each other, the first coupling coil 110 is prevented from protruding inside the innermost circumference or outside the outermost circumference of the second coupling coil 120, thereby preventing a decrease in magnetic field strength.

In other words, between the first distance (DA-DB)/2 and the second distance (DC-DD)/2, it is preferable that (DA-DB)/2 is 0.5 mm or more and 3.5 mm or less, and (DC-DD)/2 is -1.0 mm or more and 1.0 mm or less. However, this condition applies only when the innermost and outermost circumferences of the first coupling coil 110 and the second coupling coil are arranged at equal distances from the center of the IC module 7 when the IC module 7 is mounted. Note that when the second distance has a negative sign, it means that the outermost circumference of the second coupling coil 120 protrudes inward from the outermost circumference of the first coupling coil 110 by the distance of the absolute value of the second distance.

By satisfying these conditions, the overlapping area of the first coupling coil 110 and the second coupling coil 120 can be maintained substantially constant as long as the relative positional deviation between the first coupling coil 110 and the second coupling coil 120 does not exceed the smaller of the first distance and the second distance. This makes it possible to maintain relatively stable electromagnetic coupling and communication characteristics while suppressing the placement of the second coupling coil in unnecessary areas, making it even easier to guarantee the quality of the IC card 1.

(d) Method for Manufacturing a Dual Interface IC Card Next, an example of a method for manufacturing the IC card 1, which is a dual interface IC card, using the card base 2, IC module 7, and adhesive layer 11 described above will be described.

First, the antenna wire 83, which is a coated conductor wire coated with an insulating material, is embedded by a winding forming machine on the surface of the core layer 5, etc., on which the front-back conductive part 84, the lead wire 85, and the capacitance part 121 have been formed in advance, on the side not adjacent to the oversheet layer 6 or 3. The start point of the embedding is the front-back conductive part 84, and the end point is the conductive element 121a. The front-back conductive part 84 is formed into a through hole by forming a through hole in the core layer 5 and performing a conductive process such as metal plating. The lead wire 85 and the conductive elements 121a and 121b are formed by a printing method using conductive ink. The external communication antenna 80 and the second coupling coil 120 are drawn and embedded in such a core layer 5 by drawing the antenna wire 83 from the start point to the end point. After that, the supply unit cuts the antenna wire 83, and the embedding of the antenna 8 in the core layer 5, etc. is completed.

Next, as shown in the layered structure of the card base 2 in Figure 3, oversheet layer 6, core layer 5, core layer 4, and oversheet layer 3 are layered in this order from the bottom in the thickness direction. After that, the laminated unit of large sheets in which the cards are arranged vertically and horizontally in multiple faces is sandwiched between stainless steel plates from above and below in the thickness direction, and heat and pressure are applied to the laminated unit through the stainless steel plates. At this time, the antenna 8 including the capacitance section 121 is formed in advance in the core layer 5, as described above.

By going through this heat pressing process, a card base made up of large sheets in which the layers of the laminate are integrated can be obtained. Also, if either the oversheet layer or the core layer is heat resistant and does not heat fuse at a specified temperature, an adhesive sheet that heat fuses at a specified temperature can be sandwiched between the layers, or an adhesive can be applied, and then these can be subjected to a heat pressing process to obtain a card base made up of integrated large sheets.

The large-sized card base obtained as described above, on which the cards are arranged in a multi-faceted vertical and horizontal arrangement, is punched out by a punching machine into the card base 2 that is the size of an ISO/IEC 7816 card. In addition, a recess 9 for embedding the IC module 7 in the card base 2 is formed by cutting using an end mill. This results in the cut card base 2. The recess 9 is composed of a first recess 91 in which the substrate 72 is mounted, and a second recess 92 in which the IC chip 74a is housed, which is smaller than the first recess 91 when viewed from above the card base 2.

The recess 9 is formed to a depth such that the surface of the external connection terminal 71 is approximately flush with the surface of the non-cut area of the card base 2. Here, the thickness of the substrate 72 of the IC module 7 is approximately 0.07 mm or more and 0.2 mm or less, and the thickness of the IC chip body 74 is approximately 0.45 mm or more and 0.75 mm or less. The thickness of the adhesive layer 11 is usually approximately 0.03 mm or more and 0.2 mm or less. Taking these factors into consideration, the depth of the first recess 91 is usually approximately 0.1 mm or more and 0.4 mm or less, and the depth of the second recess 92 is usually approximately 0.48 mm or more and 0.78 mm or less. The depth of the second recess 92 is deeper than the depth of the first recess 91.

On the other hand, separate from the manufacturing of the card base 2 and the cutting process for forming the recess 9, the adhesive layer 11 is attached to the IC module 7. As described above, the IC module 7 has a substrate 72, an external connection terminal 71 formed on one side of the substrate 72, an IC chip 74a arranged on the other side, and a first coupling coil 110 electrically connected to the IC chip 74a so as to form a closed circuit. As the IC module 7, a module tape is usually used in which the IC module 7 is formed on a long tape in one or two rows. A tape-like adhesive layer 11 is attached to the surface of the module tape opposite to the surface on which the external connection terminal 71 is formed, while applying a certain amount of heat and pressure. Thereafter, the module tape with the adhesive layer 11 attached is punched out by a punching machine into an approximately rectangular IC module 7 with rounded corners, thereby obtaining the IC module 7 with the adhesive layer 11 attached.

Then, the IC module 7 with the adhesive layer 11 attached is embedded in the card base 2 with the recess 9 formed therein, and a predetermined heat block is pressed against the external connection terminal 71 to apply a predetermined heat pressure for a predetermined time toward the card base 2. This melts the adhesive layer 11, thereby bonding and fixing the IC module 7 to the card base 2. The application time and heat pressure conditions for the adhesive layer 11 vary depending on the type and composition, but as an example, the time can be 0.5 seconds or more and 10.0 seconds or less, the temperature can be 150°C or more and 250°C or less, and the pressure can be 20 MPa or more and 100 MPa or less.

(e) Regarding the Dual Interface IC Card of the First Embodiment In summary, the IC card 1 of the first embodiment is a dual interface IC card capable of contact communication and contactless communication with an external device. The IC card 1 includes an IC module 7 having a substrate 72, an external connection terminal 71 formed on one side of the substrate 72, an IC chip 74a disposed on the other side, and a first coupling coil 110 electrically connected to the IC chip 74a so as to form a closed circuit. The IC card 1 also includes a card base 2, a second coupling coil 120 disposed inside the card base 2 and spaced apart from and facing the first coupling coil 110, and an external communication antenna 80 connected in series to the second coupling coil 120. The second coupling coil 120 and the external communication antenna 80 constitute an antenna 8.

The IC module 7 is placed in a recess 9 provided in the card base 2 so that its external connection terminal 71 is exposed. The recess 9 is composed of a first recess 91 in which the substrate 72 is mounted, and a second recess 92 in which the IC chip 74a is housed and which is smaller than the first recess 91 in a plan view of the card base 2. In this case, in the plan view, a capacitance section 121 composed of conductive elements 121a, 121b arranged opposite and spaced apart from each other in the thickness direction is provided inside the innermost circumference of the second coupling coil 120. The antenna 8 composed of the second coupling coil 120, the capacitance section 121, and the external communication antenna 80 form a closed circuit.

As a result, in the IC card 1 of this embodiment, the capacitive section 121 is provided inside the innermost circumference of the second coupling coil 120, so even if part of the capacitive section 121 is cut during cutting, the closed circuit of the antenna 8 is prevented from being immediately disconnected. Since the capacitive section 121 has a certain width as the conductive elements 121a and 121b, the function of the capacitive section 121 is not lost unless these are completely cut and disappear, and communication with the second coupling coil 120 and the like can be performed normally.

Furthermore, if part of the capacitive portion 121 is cut during cutting, depending on the extent of the cutting, a change in capacitance occurs as the area of the conductive elements 121a and 121b is reduced, and the resonant frequency, etc. changes. As a result, by monitoring the change in the resonant frequency of the manufactured IC card 1, it is possible to estimate the degree to which the arrangement of the second coupling coil 120 and the cutting position deviate from the design values, making it possible to inspect the manufacturing conditions and the stability of product quality while preventing defects such as breakage of the antenna 8.

As described above, in this embodiment, a dual interface IC card can be provided in which the first coupling coil on the IC module side and the second coupling coil on the card base side can be electromagnetically coupled well, and disconnection of the second coupling coil can be suppressed even when the arrangement of the second coupling coil or the position of the recess is changed.

2. Second embodiment Next, an example of a second embodiment of the dual interface IC card of the present disclosure will be described. Figures 5(a), 5(b), 5(c), and 5(d) are plan views of an IC card 1a of the second embodiment corresponding to Figures 1(a), 1(b), 1(c), and 1(d) of the first embodiment, respectively. Also, Figure 6 is a cross-sectional view of the IC card 1a of Figure 5(a) taken along line B-B along the X-axis near the IC module 7, as viewed from the -Y direction side, corresponding to Figure 3.

The IC card 1 of the first embodiment has a capacitance section 121 composed of conductive elements 121a and 121b arranged opposite and spaced apart from each other in the thickness direction inside the innermost circumference of the second coupling coil 120 in a plan view along the Z axis. In contrast, the IC card 1a of the second embodiment differs from the IC card 1 in that it has a capacitance section 122 composed of conductive elements 122a and 122b arranged opposite and spaced apart from each other in the thickness direction outside the outermost circumference of the second coupling coil 120. Note that the second coupling coil 120, the capacitance section 122, and the external communication antenna 80 constitute the antenna 8a and form a closed circuit, similar to the IC card 1. Also, except for the different arrangement of the capacitance section 122, the configuration of the IC card 1a is similar to that of the IC card 1.

A flat conductive element 122a that is roughly C-shaped or U-shaped in a planar view is connected to the outside of the antenna wire 83 that forms the loop of the second coupling coil 120. The inside tip of the loop of the second coupling coil 120 is electrically connected to the conductive element 122a that straddles the loop of the second coupling coil 120 and is located outside the outermost circumference of the loop. On the other hand, the inside tip of the antenna wire 83 that forms the loop of the external communication antenna 80 is connected to the back side of the core layer 5 via the front-back conductive part 84.

That is, as shown in FIG. 5(c), on the other surface of the core layer 5, i.e., the surface on the -Z direction side, a lead wire 85 is connected a predetermined distance from the front-back conductive portion 84 to a flat conductive element 122b having a similar shape to the conductive element 122a described above, the tip of which is connected to the flat conductive element 122b. The conductive elements 122a and 122b are arranged opposite each other with the thickness of the core layer 5 between them, forming a capacitance portion 122, which is a capacitor.

As a result, the antenna 8a is configured by connecting the external communication antenna 80 and the second coupling coil 120 formed on one side of the core layer 5 in series with the capacitance section 122 formed across the front and back sides of the core layer 5, forming a closed circuit.

When the recess 9 for embedding the IC module 7 is formed in the card base 2 by cutting or the like in the IC card 1a of this embodiment, the following may occur. That is, if the arrangement or cutting position of the second coupling coil 120 deviates from the design value, the second coupling coil 120 may be damaged or the antenna wire 83 may be broken by cutting, which may result in poor contactless communication. However, the capacitance section 122, which is provided as a capacitance adjustment section to ensure good communication at a specified frequency, is located outside the outermost circumference of the second coupling coil 120, so that the resonance frequency can be prevented from fluctuating due to damage to the capacitance section 122.

Also, unlike the IC card 1 of the first embodiment, if the innermost periphery of the second coupling coil 120 is cut during cutting and the antenna wire 83 is broken, the IC card 1a will immediately be unable to perform non-contact communication. Therefore, the quality of the manufactured IC card 1a can be easily determined based on the presence or absence of non-contact communication, and defects such as the IC card being shipped as a defective product can be prevented.

The distances DA, DB, DC, DD, DE, DF, DG, and DH described based on FIG. 3 of the first embodiment are also common to the IC card 1a of the second embodiment. On the other hand, in a plan view along the Z axis, it is preferable that the capacitance section 122 is disposed at a distance of 1.0 mm or more from the additional element 200. In other words, it is preferable that DJ is 1.0 mm or more. This suppresses unevenness on the surface of the card base 2 caused by the second coupling coil 120. Therefore, the additional element 200 can be well formed on the surface of the card base 2, and the letters, symbols, facial photographs, etc. of the additional element 200 can be well viewed.

Next, we will explain this disclosure in detail for the first embodiment using examples.

(a) IC module For the IC module 7, copper foil is attached to the front and back of a glass epoxy base material, and an etching process is performed to form a pattern of the external connection terminal 71 on one side, and a pattern of the first coupling coil 110 and the lead portion 77 on the other side. In addition, each copper foil pattern is nickel-plated and gold-plated. On the other side, an IC chip 74a is mounted face-down via an adhesive so that the lead portion 77 and the pad 74p are in contact, and the periphery is sealed with an epoxy resin molded resin 74b.

The first coupling coil 110 had a line width of 0.12 mm and 8 turns, and in the cross section cut along the XZ plane in FIG. 1(a), DB = 12.3 mm and DC = 8.0 mm. In addition, in the cross section cut along the YZ plane perpendicular to this, DB = 11.1 mm and DC = 7.0 mm. Meanwhile, the self-inductance of the first coupling coil 110 was 1.0 μH.

(b) Card Base and Antenna A PET-G base material was used for the core layers 4, 5 and the oversheet layers 3, 6, and these were laminated and integrated by hot pressing so that the total thickness of the card base 2 was 0.80 mm. This was then punched out to a card size, and a recess 9 for accommodating the IC module 7 was formed, and then the IC module 7 was accommodated and fixed in the recess 9 of the card base 2 via an adhesive layer 11. Furthermore, a hologram label having a width of 20 mm along the long side direction of the card base 2 and a width of 20 mm along the short side direction was formed as an additional element 200 at a predetermined position on the surface on the +Z direction side of the card base 2 by thermal transfer using a hot stamp. The heating temperature of the hot stamp was 120° C., and the transfer time was 1.5 seconds.

The antenna wire 83 was a coated conductor wire with a diameter of 0.08 mm coated with copper wire, the number of turns of the external communication antenna 80 was 3, and the opening area was about 3500 ^mm2 . On the other hand, for the second coupling coil 120, the cross section cut on the XZ plane in Fig. 1(a) was DA = 17.5 mm, DD = 8.0 mm, DE = 6.0 mm, DF = 4.0 mm, DG = 3.0 mm, DH = 0.5 mm, and DI = 1.0 mm. Also, the cross section cut on the YZ plane perpendicular to this was DA = 17.5 mm, DD = 9.0 mm, DE = 7.0 mm, DF = 5.0 mm, DG = 4.0 mm, DH = 0.5 mm, and DI = 1.0 mm. The self-inductance of the second coupling coil 120 was 4.0 μH, and the self-inductance of the external communication antenna 80 was 1.5 μH.

Here, we created samples that change the positional relationship between the DF, DG, first coupling coil 110, and second coupling coil 120 by changing the mounting position of the recess 9 and IC module 7 on the card base 2 without changing the shape of the second coupling coil 120. The specifications of these samples are as shown in Table 1 below.

(c) Reading test results Five samples each of the above A to F were created, and the distance from the IC card 1 and the reading results for each sample using a specified contactless reader/writer are summarized in Table 2 below. The reader/writer used was a Fujifilm Corporation model ICT-3192. Table 3 shows the results of measuring the amount of distortion of the additional element 200 using samples with different DI. Furthermore, the resonance frequency was measured for samples C1 to C3 in which DH was changed in stages.

1, 1a IC card 2 Card base 3, 6 Oversheet layer 4, 5 Core layer 7 IC module 8, 8a Antenna 9 Recess 11 Adhesive layer 12 Antenna sheet 71 External connection terminal 72 Substrate 74 IC chip body 74a IC chip 74b Molded portion 74p Pad 75 Wire 76 Bonding hole 77 Lead portion 80 External communication antenna 83 Antenna line 84 Front-back conductive portion 85 Lead wire 91 First recess 91a Bottom surface 92 Second recess 110 First coupling coil 120 Second coupling coil 121, 122 Capacitive portion 121a, 122a Conductive element 121b, 122b Conductive element 200 Additional element

Claims (5)

A dual interface IC card capable of contact communication and non-contact communication with an external device,
an IC module including a substrate, an external connection terminal formed on one surface of the substrate, an IC chip disposed on the other surface of the substrate, and a first coupling coil electrically connected to the IC chip so as to form a closed circuit;
A card base;
a second coupling coil disposed inside the card body and spaced apart from and facing the first coupling coil, and an external communication antenna connected in series to the second coupling coil,
the IC module is disposed in a recess provided in the card base so that an external connection terminal of the IC module is exposed;
the recess includes a first recess in which the substrate is mounted, and a second recess in which the IC chip is housed and which is smaller than the first recess in a plan view of the card base,
a capacitance section including conductive elements disposed opposite to and spaced apart from each other in a thickness direction, the capacitance section being located inside an innermost periphery of the second coupling coil in the plan view;
A dual interface IC card, wherein the second coupling coil, the capacitance portion and the external communication antenna form a closed circuit. The dual interface IC card according to claim 1, further comprising an additional element formed by heating on the surface of the card base on which the external connection terminal is exposed, and the second coupling coil is disposed at a distance of 1.0 mm or more from the additional element in the plan view. The dual interface IC card according to claim 1, wherein, in the plan view, the second coupling coil is disposed at a distance of 2.0 mm or more and 5.0 mm or less outward from the second recess, and the second coupling coil is disposed so as to extend outward from the first recess to a distance of 0.0 mm or more and 6.5 mm or less. an innermost periphery portion of the first coupling coil is included between an innermost periphery portion and an outermost periphery portion of the second coupling coil in the plan view,
When a distance by which an innermost peripheral portion of the second coupling coil protrudes inward from an innermost peripheral portion of the first coupling coil is defined as a first distance, and a distance by which an outermost peripheral portion of the second coupling coil protrudes outward from an outermost peripheral portion of the first coupling coil is defined as a second distance,
2. The dual interface IC card of claim 1, wherein the first distance is 0.5 mm or more and 3.5 mm or less, and the second distance is −1.0 mm or more and 1.0 mm or less. The dual interface IC card of claim 1, wherein, in the plan view, the inductance of the second coupling coil is greater than the inductance of the first coupling coil.

Images