RFIC module and RFID tag

The present application is a continuation of PCT/JP2020/024786 filed Jun. 24, 2020, which claims priority to Japanese Application No. 2019-202954, filed Nov. 8, 2019, the entire contents of each of which are incorporated herein by reference.

The present invention relates to an RFIC (Radio Frequency Integrated Circuit) module and an RFID (Radio Frequency Identifier) tag including the RFIC module.

International Publication No. 2016/084658 (hereinafter “Patent Literature 1”) discloses an RFIC module to be coupled to a conductor that serves as an antenna. The RFIC module includes a substrate, an RFIC chip mounted in the substrate, and a matching circuit configured by a plurality of coils connected to the RFIC chip.

When the RFIC module having the structure disclosed in Patent Literature 1 is designed to be thinner and smaller, two coils among the plurality of coils that configure the matching circuit may be very close to each other. The coils thus disposed adjacent to each other may cause unwanted coupling between the coils. In addition, under the condition in which a plurality of RFIC modules are adjacent to each other, between the adjacent RFIC modules, the unwanted coupling easily occurs even between the coils for the matching circuits. With this configuration, the characteristics of the RFIC module and the RFID tag may be changed.

In view of the foregoing, an object of the present invention is to provide an RFIC module in which the influence of unwanted coupling between a plurality of coils configuring a matching circuit is significantly reduced and a region in which the plurality of coils configuring the matching circuit are provided is reduced.

Thus, an RFIC module according to an exemplary embodiment is provided that includes a substrate, an RFIC provided at the substrate, an RFIC side first terminal electrode and an RFIC side second terminal electrode to which the RFIC is connected. Moreover, an antenna side first terminal electrode and an antenna side second terminal electrode are provided at the substrate and are each configured to be directly connected or capacitively coupled to an antenna, and an impedance matching circuit is provided at the substrate and is connected to the RFIC side first terminal electrode, the RFIC side second terminal electrode, the antenna side first terminal electrode, and the antenna side second terminal electrode. The impedance matching circuit includes a first inductor, a second inductor, a third inductor, and a fourth inductor that are configured by a conductor pattern provided at the substrate. A first end of the first inductor is connected to the antenna side first terminal electrode, a second end of the first inductor is connected to the RFIC side first terminal electrode, a first end of the second inductor is connected to the antenna side second terminal electrode, and a second end of the second inductor is connected to the RFIC side second terminal electrode. A first end of the third inductor is connected to the antenna side first terminal electrode, a first end of the fourth inductor is connected to the antenna side second terminal electrode, and a second end of the third inductor and a second end of the fourth inductor are connected to each other. The conductor pattern that configures the first inductor, the second inductor, the third inductor, and the fourth inductor defines a single coil-shaped pattern.

In addition, an RFID tag as an exemplary embodiment is provide that includes an antenna, and an RFIC module connected or coupled to the antenna. The structure of this RFIC module is as described above.

According to the exemplary embodiments of the present invention, an RFIC module is provided in which the influence of unwanted coupling between a plurality of coils configuring a matching circuit is reduced and a region in which the plurality of coils configuring the matching circuit are provided is reduced. Moreover, an RFID tag including the RFIC module is provided.

FIG. 1A is a plan view of an RFID tag 201 according to a first exemplary embodiment. FIG. 1B is an enlarged plan view of a portion on which an RFIC module 101 included in the RFID tag 201 is mounted.

FIG. 2A is a plan view showing a conductor pattern provided at a substrate 1 of the RFIC module 101 in a state before a protective film is provided. FIG. 2B is a cross-sectional view of an X-X portion in FIG. 2A .

FIG. 3 is a plan view showing a conductor pattern provided on each layer of the substrate 1 of the RFIC module 101 .

FIG. 4 is a circuit diagram of the RFIC module 101 .

FIG. 5A is a cross-sectional view of the RFIC module 101 , and FIG. 5B is a cross-sectional view showing a state in which the RFIC module 101 is adhered to an insulating film 60 of an antenna 6 through an adhesive layer 5 .

FIG. 6 is a diagram showing a connection relationship between a third inductor L 3 , a fourth inductor L 4 , and conductor patterns 61 and 62 of the antenna.

FIG. 7A shows another RFIC module according to the first exemplary embodiment, and is a plan view of a substrate 1 of the RFIC module in a state before an RFIC 2 is mounted.

FIG. 7B is a cross-sectional view of an X-X portion in FIG. 7A in a state after the RFIC 2 has been mounted.

FIG. 8A shows an RFIC module according to a second exemplary embodiment, and is a plan view of a substrate 1 of the RFIC module in a state before an RFIC 2 is mounted. FIG. 8B is a cross-sectional view of an X-X portion in FIG. 8A in a state after the RFIC 2 has been mounted.

FIG. 9 is a cross-sectional view of the RFIC module 102 according to the second exemplary embodiment, and is a cross-sectional view in a state in which an upper surface of the substrate 1 on which the RFIC 2 is mounted is covered with a protective film 3 .

FIG. 10 is a plan view showing a conductor pattern provided at a substrate 1 of an RFIC module according to a third exemplary embodiment.

FIG. 11 is a plan view showing a conductor pattern provided at a substrate 1 of another RFIC module according to the third exemplary embodiment.

FIG. 1A is a plan view of an RFID tag 201 according to an exemplary embodiment of the present invention. FIG. 1B is an enlarged plan view of a portion on which an RFIC module 101 included in the RFID tag 201 is mounted.

As shown, the RFID tag 201 includes an antenna 6 , and an RFIC module 101 coupled to the antenna 6 . The antenna 6 includes an insulating film 60 , and conductor patterns 61 and 62 provided or otherwise disposed on this insulating film 60 . The insulating film 60 is, for example, a polyethylene terephthalate (PET) film, and the conductor patterns 61 and 62 are, for example, aluminum foil patterns.

The conductor pattern 61 includes conductor patterns 61 P, 61 L, and 61 C, and the conductor pattern 62 includes conductor patterns 62 P, 62 L, and 62 C. The conductor patterns 61 and 62 define a dipole antenna.

According to the exemplary aspect, the RFIC module 101 is mounted on the conductor patterns 61 P and 62 P. As shown, the conductor patterns 61 L and 62 L have a meander line shape and serve as a region having a high inductance component. In addition, the conductor patterns 61 C and 62 C have a planar shape and serve as a region having a high capacitance component. With this configuration, an inductance component in a high current intensity region is increased and a capacitance component in a high voltage intensity region is increased, which reduces a region in which the conductor patterns 61 and 62 of the antenna are provided.

FIG. 2A is a plan view showing a conductor pattern provided at a substrate 1 of the RFIC module 101 in a state before a protective film to be described below is provided. FIG. 2B is a cross-sectional view of an X-X portion in FIG. 2A .

This RFIC module 101 includes a substrate 1 , and an RFIC 2 mounted on the substrate 1 . The substrate 1 is, for example, a flexible substrate including polyimide or the like, and a stacked body including a first layer 1 A and a second layer 1 B.

FIG. 3 is a plan view showing a conductor pattern provided on each layer of the substrate 1 of the RFIC module 101 . The upper portion in FIG. 3 is a plan view of the second layer 1 B of the substrate 1 , and the lower portion in FIG. 3 is a plan view of the first layer 1 A of the substrate 1 .

The upper surface of the second layer 1 B of the substrate 1 includes an RFIC side first terminal electrode 51 , an RFIC side second terminal electrode 52 , a first inductor L 1 , a third inductor L 3 , and a conductor pattern L 13 . An end of the conductor pattern L 13 is connected to a first end E 11 of the first inductor L 1 and a first end E 31 of the third inductor L 3 . The upper surface of the first layer 1 A of the substrate 1 includes an antenna side first terminal electrode 11 , an antenna side second terminal electrode 12 , a second inductor L 2 , a fourth inductor L 4 , and a conductor pattern L 24 . An end of the conductor pattern L 24 is connected to a first end E 21 of the second inductor L 2 and a first end E 41 of the fourth inductor L 4 . Each of the conductor patterns is, for example, obtained by patterning copper foil by photolithography.

In addition, the second layer 1 B includes via conductors V 2 , V 13 , and V 34 . The via conductor V 34 connects a second end E 32 of the third inductor L 3 to a second end E 42 of the fourth inductor L 4 . The via conductor V 2 connects the RFIC side second terminal electrode 52 to a second end E 22 of the second inductor L 2 . The via conductor V 13 connects the other end of the conductor pattern L 13 to the antenna side first terminal electrode 11 .

The connection relationship described above, in other words, is as follows.

That is, the first end E 11 of the first inductor L 1 is connected to the antenna side first terminal electrode 11 , and the second end E 12 of the first inductor L 1 is connected to the RFIC side first terminal electrode 51 .

Moreover, the first end E 21 of the second inductor L 2 is connected to the antenna side second terminal electrode 12 , and the second end E 22 of the second inductor L 2 is connected to the RFIC side second terminal electrode 52 .

Furthermore, the first end E 31 of the third inductor L 3 is connected to the antenna side first terminal electrode 11 , and the first end E 41 of the fourth inductor L 4 is connected to the antenna side second terminal electrode 12 .

Finally, the second end E 32 of the third inductor L 3 and the second end E 42 of the fourth inductor L 4 are connected to each other.

In addition, the first inductor L 1 and the third inductor L 3 are configured by a conductor pattern wound along the second layer 1 B of the substrate 1 and having a partial shape of a coil, and the second inductor L 2 and the fourth inductor L 4 are configured by a conductor pattern wound along the first layer 1 A of the substrate 1 and having a partial shape of a coil.

Moreover, a winding direction from the first end E 11 of the first inductor L 1 to the second end E 12 of the first inductor L 1 , a winding direction from the second end E 32 of the third inductor L 3 to the first end E 31 of the third inductor L 3 , a winding direction from the first end E 41 of the fourth inductor L 4 to the second end E 42 of the fourth inductor L 4 , and a winding direction from the second end E 22 of the second inductor L 2 to the first end E 21 of the second inductor L 2 are all in the left-handed direction according to the exemplary embodiments. In other words, all the winding directions are in the same direction.

In this aspect, the first inductor L 1 , the second inductor L 2 , the third inductor L 3 , and the fourth inductor L 4 define a rectangular coil-shaped pattern.

FIG. 4 is a circuit diagram of the RFIC module 101 . As shown, the RFIC module 101 includes an RFIC 2 and an impedance matching circuit 7 . The impedance matching circuit 7 includes the first inductor L 1 , the second inductor L 2 , the third inductor L 3 , and the fourth inductor L 4 . The dot symbol in FIG. 4 indicates a coil winding direction of each inductor. As shown in FIG. 3 , a sum of the line length (i.e., the number of turns) of the first inductor L 1 and the line length (i.e., the number of turns) of the second inductor L 2 is longer than a sum of the line length (i.e., the number of turns) of the third inductor L 3 and the line length (i.e. the number of turns) of the fourth inductor L 4 . When it is expressed in terms of the magnitude of inductance, the relationship of (L 1 +L 2 )>(L 3 +L 4 ) is satisfied.

FIG. 5A is a cross-sectional view of the RFIC module 101 , and FIG. 5B is a cross-sectional view showing a state in which the RFIC module 101 is adhered to the insulating film 60 of the antenna 6 through an adhesive layer 5 . The upper surface of the substrate 1 on which the RFIC 2 is mounted is covered with a protective film 3 . The protective film 3 includes, for example, a hot melt agent such as elastomer such as polyurethane, and ethylene vinyl acetate (EVA). Both of the substrate 1 and the protective film 3 are flexible, and the entirety of the RFIC module 101 is flexible.

The adhesive layer 5 shown in FIG. 5B is a layer of an insulating adhesive material, and includes an acrylic adhesive agent, for example. The antenna side first terminal electrode 11 faces the conductor pattern 61 P of the antenna 6 through the first layer 1 A and the adhesive layer 5 , and the antenna side second terminal electrode 12 faces the conductor pattern 62 P of the antenna 6 through the first layer 1 A and the adhesive layer 5 . With this structure, the antenna side first terminal electrode 11 and the antenna side second terminal electrode 12 are respectively capacitively coupled to the conductor patterns 61 P and 62 P of the antenna 6 .

FIG. 6 is a diagram showing a connection relationship between the third inductor L 3 and the fourth inductor L 4 , and the conductor patterns 61 and 62 of the antenna. A capacitor Ca in FIG. 6 is a capacitive component generated between the conductor patterns 61 and 62 of the antenna. In addition, a capacitor C 11 is a capacitive component generated between the conductor pattern 61 of the antenna and the antenna side first terminal electrode 11 , and a capacitor C 12 is a capacitive component generated between the conductor pattern 62 of the antenna and the antenna side second terminal electrode 12 . The inductance of the inductors L 3 and L 4 and the capacitance of the capacitors Ca, C 11 , and C 12 define a parallel resonance circuit. The resonance frequency of this resonance circuit is set to match the center frequency of the communication frequency band of the RFID tag 201 .

FIG. 7A shows another RFIC module according to the first exemplary embodiment, and is a plan view of the substrate 1 of the RFIC module in a state before the RFIC 2 is mounted. FIG. 7B is a cross-sectional view of an X-X portion in FIG. 7A in a state after the RFIC 2 has been mounted.

In this example, the number of turns of a conductor pattern that configures the inductors L 1 , L 2 , L 3 , and L 4 is larger than the number of turns in the example mainly shown in FIG. 2A and FIG. 2B .

The upper surface of the second layer 1 B of the substrate 1 includes an RFIC side first terminal electrode 51 , an RFIC side second terminal electrode 52 , a first inductor L 1 , a third inductor L 3 , and a conductor pattern L 13 . The upper surface of the first layer 1 A of the substrate 1 includes an antenna side first terminal electrode 11 , an antenna side second terminal electrode 12 , a second inductor L 2 , a fourth inductor L 4 , and a conductor pattern L 24 . The second layer 1 B of the substrate 1 includes a via conductor V 34 that connects the third inductor L 3 and the fourth inductor L 4 .

As described above, even in a case in which the number of turns of the conductor pattern that configures the inductors L 1 , L 2 , L 3 , and L 4 is increased, a predetermined conductor pattern is made into a spiral shape, so that the conductor pattern that configures the inductors L 1 , L 2 , L 3 , and L 4 is able to be configured to provide a single coil-shaped pattern.

According to the present exemplary embodiment, the following advantageous effects are obtained.

(a) The conductor pattern that configures the inductors L 1 , L 2 , L 3 , and L 4 that configure the impedance matching circuit 7 defines a single coil-shaped pattern, so that a region in which the inductors L 1 , L 2 , L 3 , and L 4 that configure the matching circuit are provided is reduced. In addition, the inductors L 1 , L 2 , L 3 , and L 4 are adjacent to each other from the start, so that, as compared to a case in which when a plurality of coils that configure the inductors L 1 , L 2 , L 3 , and L 4 are arranged in parallel to each other, the coils are adjacent to each other in a plane direction, the influence of unwanted coupling between the plurality of coils is reduced.

(b) As shown in FIG. 4 , the coil winding directions of the inductors L 1 , L 2 , L 3 , and L 4 are in the same direction as that of order of the inductors L 1 , L 3 , L 4 , and L 2 . As a result of this configuration, in a current path viewed from a connection portion (i.e., the RFIC side first terminal electrode 51 and the RFIC side second terminal electrode 52 ) of the RFIC 2 (e.g., a feeding circuit), the inductors L 1 , L 2 , L 3 , and L 4 do not reduce the magnetic flux of each other, and predetermined inductance is able to be obtained, which also results in reducing the region in which the inductors L 1 , L 2 , L 3 , and L 4 are provided.

(c) The substrate 1 includes the first layer 1 A and the second layer 1 B, the first inductor L 1 and the third inductor L 3 are configured on the second layer 1 B of the substrate 1 , and the second inductor L 2 and the fourth inductor L 4 are configured on the first layer 1 A of the substrate 1 . As a result, a pair of the first inductor L 1 with a relatively large inductance and the third inductor L 3 with a relatively small inductance, and a pair of the second inductor L 2 with a relatively large inductance and the fourth inductor L 4 with a relatively small inductance are disposed at different layers, which also results in reducing the region in which the inductors L 1 , L 2 , L 3 , and L 4 , are provided.

(d) The inductance of the inductors L 1 , L 2 , L 3 , and L 4 has a relationship of (L 1 +L 2 )>(L 3 +L 4 ), so that the matching with an RFIC that has usually an impedance value 10 times or more than the impedance of an antenna is easily performed. In addition, the inductors L 1 and L 2 are disposed on the inner peripheral side of the coil pattern, so that the inductors L 1 and L 2 with a plurality of turns are able to be easily provided, and the inductors L 3 and L 4 are disposed on the outer peripheral side of the coil pattern, so that the wiring of the impedance matching circuit 7 to the antenna side first terminal electrode 11 and the antenna side second terminal electrode 12 is easily performed.

Second Exemplary Embodiment

A second exemplary embodiment describes an example in which inductors L 1 , L 2 , L 3 , and L 4 are provided on a single layer of a substrate.

FIG. 8A shows an RFIC module according to the second exemplary embodiment, and is a plan view of a substrate 1 of the RFIC module in a state before an RFIC 2 is mounted. FIG. 8B is a cross-sectional view of an X-X portion in FIG. 8A in a state after the RFIC 2 has been mounted. FIG. 9 is a cross-sectional view of an RFIC module 102 according to the present exemplary embodiment, and is a cross-sectional view in a state in which an upper surface of the substrate 1 on which the RFIC 2 is mounted is covered with a protective film 3 .

In this example, a conductor pattern that configures the inductors L 1 , L 2 , L 3 , and L 4 is provided on the upper surface of a second layer 1 B of the substrate 1 .

The upper surface of the second layer 1 B of the substrate 1 includes an RFIC side first terminal electrode 51 , an RFIC side second terminal electrode 52 , a first inductor L 1 , a second inductor L 2 , a third inductor L 3 , and a fourth inductor L 4 . The upper surface of a first layer 1 A of the substrate 1 includes an antenna side first terminal electrode 11 , an antenna side second terminal electrode 12 , a conductor pattern L 13 , a conductor pattern L 24 , and a conductor pattern L 52 . In addition, the second layer 1 B of the substrate 1 includes a via conductor V 13 that connects the first inductor L 1 and the third inductor L 3 , a via conductor V 24 that connects the second inductor L 2 and the fourth inductor L 4 , and a via conductor V 52 that connects the second inductor L 2 and the conductor pattern L 52 .

As described above, even in a case in which the four inductors L 1 , L 2 , L 3 , and L 4 are provided on a single layer, since a predetermined conductor pattern is made into a spiral shape, the conductor pattern that configures the inductors L 1 , L 2 , L 3 , and L 4 is able to be provided on a single layer of the substrate 1 .

It is noted that the antenna side first terminal electrode 11 and the antenna side second terminal electrode 12 may be provided on the same layer as the layer including the inductors L 1 , L 2 , L 3 , and L 4 .

Third Exemplary Embodiment

A third exemplary embodiment describes an example of an RFIC module configured such that an RFIC side first terminal electrode 51 and an RFIC side second terminal electrode 52 do not overlap with a coil opening of a coil-shaped pattern that configures inductors L 1 , L 2 , L 3 , and L 4 .

FIG. 10 is a plan view showing a conductor pattern provided at a substrate 1 of the RFIC module according to the third exemplary embodiment. FIG. 11 is a plan view showing a conductor pattern provided at a substrate 1 of another RFIC module according to the third exemplary embodiment. In FIG. 10 and FIG. 11 , the position at which the RFIC 2 is mounted is indicated by a two-dot chain line.

In the example shown in FIG. 10 , a conductor pattern that configures inductors L 1 , L 2 , L 3 , and L 4 , conductor patterns L 13 , L 24 , L 51 , and L 52 , a via conductor V 34 , an antenna side first terminal electrode 11 , an antenna side second terminal electrode 12 , an RFIC side first terminal electrode 51 , and an RFIC side second terminal electrode 52 are provided at the substrate 1 .

In the example shown in FIG. 11 , a conductor pattern that configures inductors L 1 , L 2 , L 3 , and L 4 , conductor patterns L 13 , L 24 , L 51 , and L 52 , via conductors V 13 , V 24 , and V 51 , an antenna side first terminal electrode 11 , an antenna side second terminal electrode 12 , an RFIC side first terminal electrode 51 , and an RFIC side second terminal electrode 52 are provided at the substrate 1 .

In either of the examples shown in FIG. 10 and FIG. 11 , the conductor pattern that configures the inductors L 1 , L 2 , L 3 , and L 4 is provided so as to extend around a single coil opening CO. Moreover, the RFIC side first terminal electrode 51 and the RFIC side second terminal electrode 52 are provided at a position that does not overlap with the coil opening CO.

According to the present exemplary embodiment, since the RFIC 2 does not block the magnetic flux that passes through the coil opening CO of the inductors L 1 , L 2 , L 3 , and L 4 , the characteristic degradation of the inductors L 1 , L 2 , L 3 , and L 4 due to the presence of the RFIC 2 is avoided. In addition, the characteristic change due to the deviation of the mounting position of the RFIC 2 is also avoided. Moreover, since the RFIC 2 causes no reduction in the inductance of the inductors L 1 , L 2 , L 3 , and L 4 , the coil opening CO of the conductor pattern that configures the inductors L 1 , L 2 , L 3 , and L 4 is made smaller. With this configuration, the overall size is not increased even when the RFIC 2 is disposed outside of the coil opening CO.

In general, it is noted that the description of the above exemplary embodiments is illustrative in all respects, but not restrictive. Modifications and changes are able to appropriately be made by those skilled in the art.

For example, in the example shown in FIG. 5B , while the antenna side first terminal electrode 11 and the conductor pattern 61 P of the antenna are capacitively coupled and the antenna side second terminal electrode 12 and the conductor pattern 62 P of the antenna are capacitively coupled, this capacitive coupling portion may be directly (e.g., in a direct current manner) connected. Alternatively, one may be directly connected and the other may be capacitively coupled.

In addition, in any of the exemplary embodiments described above, while the example in which the RFIC 2 is mounted on the upper surface of the substrate 1 has been shown, the RFIC 2 may be disposed inside of the substrate 1 . For example, the RFIC side first terminal electrode 51 and the RFIC side second terminal electrode 52 may be provided on the first layer 1 A, and the RFIC 2 may be provided on the first layer 1 A. In such a case, an opening (e.g., a cavity) may be provided on the second layer 1 B to avoid interference with the RFIC 2 .

Ca, C 11 , C 12 —capacitor

CO—coil opening

E 11 —first end of a first inductor L 1

E 12 —second end of a first inductor L 1

E 21 —first end of a second inductor L 2

E 22 —second end of a second inductor L 2

E 31 —first end of a third inductor L 3

E 32 —second end of a third inductor L 3

E 41 —first end of a fourth inductor L 4

E 42 —second end of a fourth inductor L 4

L 1 —first inductor

L 2 —second inductor

L 3 —third inductor

L 4 —fourth inductor

L 13 , L 24 , L 51 , L 52 —conductor pattern

V 2 , V 13 , V 34 , V 24 , V 51 , V 52 —via conductor

1 —substrate

1 A—first layer

1 B—second layer

2 —RFIC

3 —protective film

5 —adhesive layer

6 —antenna

7 —impedance matching circuit

11 —antenna side first terminal electrode

12 —antenna side second terminal electrode

51 —RFIC side first terminal electrode

52 —RFIC side second terminal electrode

60 —insulating film

61 , 62 —conductor pattern

61 P, 61 L, 61 C—conductor pattern

62 P, 62 L, 62 C—conductor pattern

101 , 102 —RFIC module

201 —RFID tag