JP7733359B2 - RFID module - Google Patents

Description

The present invention relates to an RFID module having a substrate on which a coil conductor is mounted.

Traditionally, products are managed by attaching an RFID (Radio-Frequency Identification) module, a wireless communication device, to them. One form of RFID module consists of an RFIC (Radio-Frequency Integrated Circuit) chip and a coil conductor that functions as an antenna, placed on an insulating substrate.

For example, Patent Document 1 proposes an RFID module having a coil conductor in which coil elements with legs for mounting are arranged in a row.

International Publication No. 2018-235714

The coil conductor in the RFID module disclosed in Patent Document 1 is placed inside a mold, so the opening of the coil conductor is narrow, reducing the communication characteristics as an antenna.

The present invention aims to provide an RFID module with improved communication characteristics.

An RFID module according to one aspect of the present invention comprises a substrate, a first electrode and a second electrode disposed on the substrate, a coil element connected at one end to the first electrode and at the other end to the second electrode, an RFIC chip electrically connected at one end to the first electrode and at the other end to the second electrode, and a first insulating layer covering the RFIC chip. The coil element wraps around the substrate, with at least a portion exposed outside the first insulating layer.

The present invention makes it possible to provide an RFID module with improved communication characteristics.

FIG. 1 is a perspective view showing an outline of an RFID module according to a first embodiment; Transparent side view of RFID module A longitudinal cross-sectional view of an RFID module with the coil element omitted FIG. 1 is a plan view showing electrodes arranged on a substrate; An explanatory diagram explaining the opening area FIG. 1 is an explanatory diagram illustrating a method for forming a resist layer. FIG. 10 is a plan view showing an outline of an RFID module according to a second embodiment; 8 is a cross-sectional view taken along line A-A of FIG. FIG. 10 is a longitudinal sectional view of an RFID module according to a third embodiment. FIG. 10 is a plan view showing electrodes arranged on a substrate according to a third embodiment; 10 is a side view of an RFID module according to a fourth embodiment of the present invention; FIG. 10 is a longitudinal sectional view of an RFID module according to a fourth embodiment. Equivalent circuit diagram of the RFID module of the fourth embodiment

The embodiments described below each illustrate a specific example of the present invention, and the present invention is not limited to this configuration. Furthermore, the numerical values, shapes, configurations, steps, and step orders specifically shown in the following embodiments are merely examples and do not limit the present invention. Of the components in the following embodiments, components that are not described in the independent claims that represent the highest concept are described as optional components. Furthermore, in all embodiments, the configurations in each variation are the same, and the configurations described in each variation may be combined with each other.

(Embodiment 1)
Next, a schematic configuration of an RFID module 1 according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a perspective view of the RFID module 1 according to the first embodiment. FIG. 2 is a perspective side view of the RFID module 1. FIG. 3 is a longitudinal cross-sectional view of the RFID module 1 with the coil element 6 omitted. In the figures, the X-Y-Z coordinate system is used to facilitate understanding of the invention and does not limit the invention. The X-axis direction indicates the longitudinal direction of the RFID module 1, the Y-axis direction indicates the depth (width) direction, and the Z-axis direction indicates the thickness direction. The X, Y, and Z directions are perpendicular to one another. In addition, in the following description of the embodiment, the positive direction of the Z axis is defined as the upward direction, and the negative direction of the Z axis is defined as the downward direction.

The RFID module 1 of this embodiment includes a substrate 3, a coil element 6 and an RFIC chip 7 disposed on a first main surface 4, which is the upper surface of the substrate 3, and a resin layer 10 that seals the coil element 6 and the RFIC chip 7. The RFID module 1 is, for example, a cube or rectangular parallelepiped.

The RFIC chip 7 has a first terminal 8 and a second terminal 9, which are input/output terminals. The substrate 3 in embodiment 1 is a double-sided substrate, and the second main surface 5, which is the underside of the substrate 3, and the first main surface 4 face each other. The substrate 3 is insulating, and may be, for example, a glass epoxy substrate or a ceramic substrate.

A resist layer 17 is laminated on the second main surface 5 of the substrate 3. The resist layer 17 covers and protects the first electrode 29 and second electrode 31 arranged on the second main surface 5, which will be described later. The resist layer 17 is, for example, an insulating resin layer.

1 and 2, the coil element 6 is configured by winding a conducting wire 41 multiple times around the winding axis Wa, and the coil element 6 functions as an antenna. The communication frequency band in the RFID module 1 of this embodiment is, for example, the UHF band from 860 MHz to 960 MHz. The number of turns and dimensions of the coil element 6 may be changed according to the communication characteristics.

The coil element 6 has a first end 44 connected to the first electrode 29 and a second end 45 connected to the second electrode 31. The coil element 6 is an air-core coil with an internal cavity. The winding pitch of the conductor 41 is larger than the wire diameter of the conductor 41. As a result, the coil element 6 has gaps between adjacent wound conductors 41, which makes it easier for the magnetic field generated by the coil element 6 to be released to the outside and facilitates magnetic field coupling, thereby improving communication characteristics.

The conductor 41 may have a conductive core wire and an insulating film covering the outer periphery of the core wire, or may consist of only the core wire. If the conductor 41 has an insulating film, the insulating film is peeled off at the joints between the coil element 6 and the first electrode 29 and the second electrode 31, respectively, and the core wire is joined to the respective electrodes. The conductor 41 and the first electrode 29 and the second electrode 31 are fixed by heating or laser irradiation. After connecting the conductor 41 to either the first electrode 29 or the second electrode 31, the coil element 6 is wound around the substrate 3 and the resin layer 10 and then connected to the other of the first electrode 29 and the second electrode 31. If the conductor 41 consists of only the core wire, an insulating film is formed to coat the coil element 6 exposed from the substrate 3 and the resin layer 10.

As shown in Figure 3, the resin layer 10 as the first insulating layer seals the RFIC chip 7 and is laminated on the first main surface 4 of the substrate 3. The resin layer 10 is formed of a general sealing resin such as epoxy resin.

Next, the substrate 3 will be described with reference to Figures 3 and 4. Figure 4 is a plan view showing the wiring electrodes on the substrate 3. Figure 4(a) is a plan view showing the wiring electrodes on the first main surface 4 of the substrate 3. Figure 4(b) is a perspective plan view looking through the substrate 3, showing the wiring electrodes on the second main surface 5. The dashed dotted lines in Figure 4 indicate through-hole connections.

3 and 4(a), a first land 19 connected to the first terminal 8 of the RFIC chip 7 via solder 23, and a second land 21 connected to the second terminal 9 of the RFIC chip 7 via solder 23 are arranged on the first main surface 4 of the substrate 3. Also arranged on the first main surface 4 of the substrate 3 are an electrode 27 that faces the first land 19 in the longitudinal direction of the substrate 3, and a conductor pattern 25 that connects the first land 19 and the electrode 27. The conductor pattern 25 has, for example, a linear shape extending in the longitudinal direction of the substrate 3.

A second interlayer connection conductor 57 and a first interlayer connection conductor 55 are formed to penetrate the interior of the substrate 3. The first interlayer connection conductor 55 is a conductive via that connects the electrode 27 and the first electrode 29. The second interlayer connection conductor 57 is a conductive via that connects the second land 21 and the second electrode 31.

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

A first electrode 29 and a second electrode 31 are arranged on the second main surface 5 of the substrate 3, and are connected to the first end 44 and the second end 45 of the coil element 6, respectively. The first electrode 29 and the second electrode 31 face each other in the longitudinal direction of the substrate 3.

The first terminal 8 of the RFIC chip 7 is connected to the first end 44 of the coil element 6 via the solder 23, the first land 19, the conductor pattern 25, the electrode 27, the first interlayer connecting conductor 55, and the first electrode 29.

The second terminal 9 of the RFIC chip 7 is connected to the second end 45 of the coil element 6 via the solder 23, the second land 21, the second interlayer connection conductor 57, and the second electrode 31.

An LC parallel resonant circuit is configured within the RFID module 1 and is matched to radio waves of the communication frequency, so when the coil element 6 receives radio waves of the communication frequency, a current flows through the RFIC chip 7.

The portion of the conductor 41 of the coil element 6 that contacts the second main surface 5 of the substrate 3, and the first electrode 29 and second electrode 31 on the second main surface, are covered and protected by a resist layer 17. This prevents short-circuiting between the metal outside the RFID module 1 and the coil element 6, first electrode 29, and second electrode 31, and prevents the resonant frequency of the RFIC chip 7 from being affected.

In one turn of the conductor 41 of the coil element 6, the conductor 41 protrudes from inside one side of the resist layer 17 of the RFID module 1, then wraps around one side of the substrate 3 and the resin layer 10, the top surface of the resin layer 10, and the surface facing the one side of the substrate 3 and the resin layer 10, before again re-entering the interior from the surface facing the one side of the resist layer 17. In this way, the coil element 6 wraps around the outer periphery of the resin layer 10.

The longitudinal cross section of the RFID module 1 perpendicular to the winding axis Wa of the coil element 6 is rectangular, and therefore the opening P of the coil element 6 formed by the conductor 41 wound around a portion of the outer periphery of the RFID module 1 is also rectangular when viewed from the winding axis Wa, as shown in Figure 5(a). Therefore, compared to the circular coil-shaped coil element 91 shown in Figure 5(b), assuming the diameter R of the circle and the side length L of the rectangle are the same, the rectangular opening has a larger opening area, and therefore the RFID module 1 of embodiment 1 has better antenna characteristics.

The manufacturing procedure for the RFID module 1 will now be described. First, the conductors, namely the first land 19, second land 21, conductor pattern 25, electrode 27, first electrode 29, and second electrode 31, are patterned on a large double-sided board, for example, by photolithography using copper foil. At this time, the wiring for multiple RFID modules 1 is patterned.

Next, an RFIC chip 7 is mounted on each of the first lands 19 and second lands 21, and the RFIC chip 7 on the substrate is molded with a resin layer 10. The molded large-sized double-sided substrate is then diced into individual modules. At this time, barrel processing may be performed to round off the corners of the individual modules. Next, as shown in FIG. 6, the second main surface 5 side of the substrate 3 of each individual module 2 is immersed in, for example, a UV-curable resin liquid 101, which is then applied to the second main surface 5 side and irradiated with UV light, thereby forming a resist layer 17 and manufacturing the RFID module 1.

As described above, the RFID module 1 of embodiment 1 includes the substrate 3, the first electrode 29 and the second electrode 31 arranged on the substrate 3, the coil element 6 connected at one end to the first electrode 29 and the other end to the second electrode 31, the RFIC chip 7 electrically connected at one end to the first electrode 29 and the other end to the second electrode 31, and the resin layer 10 covering the RFIC chip 7. The coil element 6 wraps around the substrate 3, with at least a portion exposed to the outside of the resin layer 10.

With this configuration of RFID module 1, at least a portion of coil element 6 is exposed outside resin layer 10, so that a portion of coil element 6 reaches the outer periphery of RFID module 1, allowing the opening of coil element 6 to be widened. This allows a magnetic field to be radiated widely from coil element 6, improving the communication characteristics of coil element 6 as an antenna.

By placing the RFID module 1, for example, inside a metal coil spring, the coil spring can be excited, thereby increasing the communication distance.

The substrate 3 has a first main surface 4 and a second main surface 5 facing each other, with the RFIC chip 7 arranged on the first main surface 4 and the first electrode 29 and second electrode 31 arranged on the second main surface 5. The RFID module 1 has a resin layer 10 arranged on the first main surface 4 to cover the RFIC chip 7, and a resist layer 17 on the second main surface 5 to cover the first electrode 29 and second electrode 31. The coil element 6 is wound around the substrate 3 and the resin layer 10.

This allows the coil element 6 to be exposed to the outside of the top and side surfaces of the resin layer 10, thereby making it possible to enlarge the opening of the coil element 6 and further improving communication characteristics.

(Embodiment 2)
Next, an RFID module 1A according to a second embodiment will be described with reference to Fig. 7 and Fig. 8. Fig. 7 is a plan view showing an outline of the RFID module 1A according to the second embodiment. Fig. 8 is a cross-sectional view taken along line AA in Fig. 7.

The substrate 3A in embodiment 2 is a single-sided substrate. Other than this and the points described below, the configuration of the RFID module 1A in embodiment 2 is the same as that of the RFID module 1 in embodiment 1, and a description of the common configuration will be omitted.

The thickness of substrate 3A in embodiment 2 is greater than the thickness of substrate 3 in embodiment 1, for example, approximately 1 mm.

In embodiment 2, the first land 19A extends from the center of the substrate 3A to one end in the longitudinal direction, and the second land 21A extends from the center of the substrate 3A to the other end in the longitudinal direction. The first end 44A of the coil element 6A is connected to one end of the first land 19A, and the second end 45A of the coil element 6A is connected to the other end of the second land 21A. The first land 19A on the center side of the substrate 3A is connected to the first terminal 8 of the RFIC chip 7 via solder 23. The second land 21A on the center side of the substrate 3A is connected to the second terminal 9 of the RFIC chip 7 via solder 23.

An insulating resist layer 18 is laminated on the first land 19A opposite the substrate 3A, except for the connection portion with the first end 44A of the coil element 6A and the connection portion with the solder 23. An insulating resist layer 18 is also laminated on the second land 21A opposite the substrate 3A, except for the connection portion with the second end 45A of the coil element 6A and the connection portion with the solder 23. This prevents electrical continuity between the coil element 6A and the first land 19A and second land 21A, even when the conductive wire 41 of the coil element 6A is wound from one end of the first land 19A around the substrate 3A, the first land 19A, and the second land 21A.

The conductor 41 of the coil element 6A in embodiment 2 has a conductive core wire and an insulating film covering the outer periphery of the core wire. In this case, it is also possible to communicate by placing the second main surface 5A of the RFID module 1A on a metal surface so that it faces the metal surface. In this case, the RFID module 1A can communicate by exciting the metal surface. If the conductor 41 is composed of only a core wire, a resin layer may be formed to cover the coil element 6A on the second main surface 5A side of the substrate 3A.

An insulating resin layer 10A is laminated on the first main surface 4A of the substrate 3A, covering the RFID module 1A, first land 19A, second land 21A, and coil element 6A. The resin layer 10A does not need to be formed by resin molding and may be formed, for example, from a UV-curable resin. In this case, the resin layer is not formed by resin molding, so the RFID module 1 can be manufactured inexpensively.

Also, as shown in Figure 7, the RFIC chip 7 is positioned at the longitudinal center of the coil element 6A in a planar view. Since the coil element 6A is positioned symmetrically around the RFIC chip 7, symmetrical communication characteristics can be obtained.

Furthermore, on the first main surface 4A side of the substrate 3A, the coil element 6A and the RFIC chip 7 do not overlap in a planar view. This reduces the influence of the magnetic field induced by the current flowing through the coil element 6A on the RFIC chip 7. It also reduces the load on the RFIC chip caused by the tension of the coil element winding.

In the RFID module 1A of embodiment 2, the substrate 3A has a first principal surface 4A and a second principal surface 5A that face each other, and the RFIC chip 7, a first land 19A serving as a first electrode, and a second land 21A serving as a second electrode are arranged on the first principal surface 4A side. The coil element 6A is wound around the substrate 3A, and at least a portion of it is exposed to the outside of the resin layer 10A.

As a result, in the RFID module 1A of embodiment 2, like the RFID module 1 of embodiment 1, at least a portion of the coil element 6A is exposed to the outside of the resin layer 10A, thereby improving the communication characteristics of the coil element 6 as an antenna.

(Embodiment 3)
Next, an RFID module 1B according to a third embodiment will be described with reference to Fig. 9 and Fig. 10. Fig. 9 is a plan view showing an outline of an RFID module 1B according to the third embodiment, from which the coil element is omitted. Fig. 10 is a plan view showing electrodes arranged on a substrate 3.

In embodiment 3, the connection point between the interlayer connection conductor and the electrode disposed on the second main surface 5 of the substrate 3 is offset from the connection point between this electrode and the coil element 6. Other than this and the points described below, the configuration of the RFID module 1B of embodiment 3 is the same as that of the RFID module 1 of embodiment 1, and a description of the common configuration will be omitted.

As shown in Figures 9 and 10(a), a first land 19B connected to the first terminal 8 of the RFIC chip 7 via solder 23 and a second land 21B connected to the second terminal 9 of the RFIC chip 7 via solder 23 are arranged on the first main surface 4, which is the upper surface of the substrate 3.

The first land 19B has an electrode 19Ba connected to the first terminal 8 of the RFIC chip 7, and an electrode 19Bb extending outward from the electrode 19Ba in the longitudinal direction of the substrate 3. The tip of the electrode 19Bb is connected to the upper end of the first interlayer connection conductor 55B that penetrates the substrate 3, and the lower end of the first interlayer connection conductor 55B is connected to the first electrode 29B arranged on the second main surface 5, which is the lower surface of the substrate 3.

The second land 21B has an electrode 21Ba connected to the second terminal 9 of the RFIC chip 7, and an electrode 21Bb extending outward from the electrode 21Ba in the longitudinal direction of the substrate 3. The tip of the electrode 21Bb is connected to the upper end of the second interlayer connection conductor 57B that penetrates the substrate 3, and the lower end of the second interlayer connection conductor 57B is connected to the second electrode 31B arranged on the second main surface 5, which is the lower surface of the substrate 3.

The first electrode 29B disposed on the second principal surface 5 of the substrate 3 includes an electrode 29Ba connected to the first interlayer connection conductor 55B, a wiring 29Bb extending from the electrode 29Ba outward in the longitudinal direction of the substrate 3, and an electrode 29Bc connected to the outer end of the wiring 29Bb. The electrode 29Bc is connected to the first end 44 of the coil element 6.

The second electrode 31B disposed on the second principal surface 5 of the substrate 3 includes an electrode 31Ba connected to the second interlayer connection conductor 57B, a wiring 31Bb extending from the electrode 31Ba outward in the longitudinal direction of the substrate 3, and an electrode 31Bc connected to the outer end of the wiring 31Bb. The electrode 31Bc is connected to the second end 45 of the coil element 6.

Electrode 29Ba and wiring 29Bb of first electrode 29B are covered and protected by resist layer 61. Electrode 31Ba and wiring 31Bb of second electrode 31B are also covered and protected by resist layer 61. The connection portions between the coil element 6 and the respective electrodes 29Bc and 31Bc arranged on the second main surface 5 of the substrate 3 are exposed and not covered by resist layer 61.

The first terminal 8 of the RFIC chip 7 is connected to the first end 44 of the coil element 6 via solder 23, first land 19B, first interlayer connection conductor 55B, and first electrode 29B. The second terminal 9 of the RFIC chip 7 is connected to the second end 45 of the coil element 6 via solder 23, second land 21B, second interlayer connection conductor 57B, and second electrode 31B.

In the case of an electrode on the second main surface 5 of the substrate 3 that is connected to an interlayer connection conductor and a coil element, if the electrode and coil element are connected along the extension of the interlayer connection conductor, the step in the interlayer connection conductor may affect the connection with the coil element.

The RFID module 1B of embodiment 3 includes a first interlayer connection conductor 55B that connects the RFIC chip 7 and the first electrode 29B by penetrating the substrate 3, and a second interlayer connection conductor 57B that connects the RFIC chip 7 and the second electrode 31B by penetrating the substrate 3. Electrode 29Bc, which is the connection point between the first electrode 29B and the coil element 6, is located further outward in the longitudinal direction of the substrate 3 than electrode 29Ba, which is the connection point between the first electrode 29B and the first interlayer connection conductor 55B. Electrode 31Bc, which is the connection point between the second electrode 31B and the coil element 6, is located further outward in the longitudinal direction of the substrate 3 than electrode 31Ba, which is the connection point between the second electrode 31B and the second interlayer connection conductor 57B. In this way, the electrode 29Ba connected to the first interlayer connection conductor 55B and the electrode 29Bc connected to the first end 44 of the coil element 6 are positioned apart from each other, which prevents a step at the connection portion between the first interlayer connection conductor 55B and the electrode 29Ba from affecting the connection between the electrode 29Bc and the first end 44 of the coil element 6. Similarly, it is possible to prevent a step at the connection portion between the second interlayer connection conductor 57B and the electrode 31Ba from affecting the connection between the second end 45 of the coil element 6 and the electrode 31Bc.

Furthermore, in the RFID module 1B of embodiment 3, a matching capacitor 11 is connected in parallel to the RFIC chip 7 to the electrode 19Ba of the first land 19B and the electrode 21Ba of the second land 21B. The capacitance component of the capacitor 11 can reduce the resonant frequency of the RFID module 1B. Note that the RFID module 1B may be configured without the capacitor 11.

(Embodiment 4)
Next, an RFID module 1C according to a fourth embodiment will be described with reference to Figs. 11 to 13. Fig. 11 is a side view showing an outline of the RFID module 1C according to the third embodiment. Fig. 12 is a longitudinal sectional view of the RFID module 1C. Fig. 13 is an equivalent circuit diagram of the RFID module 1C.

The coil element 6C in embodiment 4 extends in the longitudinal direction of the substrate 3, winding outward beyond the substrate 3 and the resin layer 10. Other than this and the points described below, the configuration of the RFID module 1C in embodiment 4 is the same as that of the RFID module 1 in embodiment 1 or the RFID module 1B in embodiment 3, and a description of the common configuration will be omitted.

As shown in Figure 12, a first land 19C connected to the first terminal 8 of the RFIC chip 7 via solder 23 and a second land 21C connected to the second terminal 9 of the RFIC chip 7 via solder 23 are arranged on the first main surface 4, which is the upper surface of the substrate 3.

The outer end of the first land 19C in the longitudinal direction of the substrate 3 is connected to the upper end of a first interlayer connection conductor 55 that penetrates the substrate 3, and the lower end of the first interlayer connection conductor 55 is connected to a first electrode 29 disposed on the second main surface 5 of the substrate 3. The first electrode 29 is joined to the first connection portion 44C of the coil element 6C, for example, by solder 47. The first electrode 29 and the first connection portion 44C of the coil element 6C may be joined electrically by welding or ultrasonic waves, in addition to solder 47.

The outer end of the second land 21C in the longitudinal direction of the substrate 3 is connected to the upper end of a second interlayer connection conductor 57 that penetrates the substrate 3, and the lower end of the second interlayer connection conductor 57 is connected to a second electrode 31 disposed on the second main surface 5 of the substrate 3. The second electrode 31 is joined to the second connection portion 45C of the coil element 6C, for example, by solder 47. The second electrode 31 and the second connection portion 45C of the coil element 6C may be joined electrically by welding or ultrasonic waves, in addition to solder 47.

As shown in FIG. 13 , the RFIC chip 7 has a feed point 7a and a capacitance C1 inside. A first terminal 8 electrically connected to one of the feed point 7a and the capacitance C1 is connected to the first connection portion 44C of the coil element 6C via solder 23, a first land 19C, a first interlayer connection conductor 55, and a first electrode 29. A second terminal 9 electrically connected to the other of the feed point 7a and the capacitance C1 is connected to the second connection portion 45C of the coil element 6C via solder 23, a second land 21C, a second interlayer connection conductor 57, and a second electrode 31.

The joint between the first electrode 29 and the first connection portion 44C of the coil element 6C, which is joined by solder 47, is covered and protected by an insulating resist layer 17 such as resin. The joint between the second electrode 31 and the second connection portion 45C of the coil element 6C, which is joined by solder 47, is also covered and protected by a resist layer 17.

The coil element 6C has a first coil extension 6Ca and a second coil extension 6Cb that protrude further in the longitudinal direction of the substrate 3 than the substrate 3 and the resin layer 10. This allows the coil element 6C to function as a dipole antenna, further improving communication performance.

As such, according to the RFID module 1C of embodiment 4, the coil element 6C has a first coil extension 6Ca on one side that extends from the connection with the first electrode 29 further outward from the substrate 3, and a second coil extension 6Cb on the other side that extends from the connection with the second electrode 31 further outward from the substrate 3 in the opposite direction to the extension of the first coil extension 6Ca. This further improves the communication performance of the RFID module 1C.

The present invention is not limited to the above embodiments and can be modified as follows:

In the above-mentioned embodiment 1, the RFIC chip 7 was arranged at the end of the substrate 3, but this is not limited to this. As in embodiment 2, the RFIC chip 7 may be arranged in the center of the substrate 3 together with the first land 19 and the second land 21. This places the RFIC chip 7 in the longitudinal center of the coil element 6 in a planar view. When the coil element 6 is arranged symmetrically around the RFIC chip 7, symmetrical communication characteristics can be obtained. In addition, the load transmitted to the RFIC chip 7 when connecting the coil element 6 to the first electrode 29 and the second electrode 31 can be reduced.

While the present invention has been described in detail in each embodiment, the disclosure of these embodiments may vary in structural details, and variations in the combination and order of elements in each embodiment may be realized without departing from the scope and spirit of the invention as claimed.

The RFID module of the first aspect of the present invention comprises a substrate, a first electrode and a second electrode disposed on the substrate, a coil element connected at one end to the first electrode and at the other end to the second electrode, an RFIC chip electrically connected at one end to the first electrode and at the other end to the second electrode, and a first insulating layer covering the RFIC chip. The coil element wraps around the substrate, with at least a portion exposed to the outside of the first insulating layer.

In this RFID module, at least a portion of the coil element is exposed to the outside of the first insulating layer, so that a portion of the coil element reaches the outer periphery of the RFID module, allowing the opening of the coil element to be widened. This allows the magnetic field to be radiated widely from the coil element, improving the communication characteristics of the coil element as an antenna.

According to the second aspect, in the RFID module of the first aspect, the coil element has a conductor wound multiple times, and the winding pitch of the conductor is larger than the wire diameter of the conductor. As a result, the coil element has gaps between adjacent wound conductors, which makes it easier for the magnetic field generated by the coil element to be released to the outside and facilitates magnetic field coupling, thereby improving communication characteristics.

According to a third aspect, in the RFID module of the first or second aspect, the substrate has a first principal surface and a second principal surface facing each other, an RFIC chip is disposed on the first principal surface, a first electrode and a second electrode are disposed on the second principal surface, a first insulating layer covering the RFIC chip is disposed on the first principal surface, and a second insulating layer is provided on the second principal surface covering at least a portion of the first electrode and the second electrode, and the coil element is wound around the substrate and the first insulating layer. This makes it possible to use a double-sided substrate as the substrate, and even with this configuration, it is possible to realize an RFID module with improved communication characteristics.

According to the fourth aspect, in an RFID module according to any one of the first to third aspects, the cross section of the first insulating layer perpendicular to the winding axis of the coil element is rectangular. Since the opening of the coil element can be made rectangular, communication characteristics can be improved compared to a coil element with a circular opening.

According to the fifth aspect, the substrate of the first or second aspect has a first main surface and a second main surface that face each other, and the RFIC chip, first electrode, and second electrode are arranged on the first main surface. This makes it possible to use a single-sided substrate as the substrate, and even with this configuration, it is possible to realize an RFID module with improved communication characteristics.

According to the sixth aspect, in the RFID module of any one of the first to third aspects, the RFIC chip is arranged in the longitudinal center of the coil element in a planar view. This allows the coil elements to be arranged symmetrically around the RFIC chip, thereby achieving symmetric communication characteristics.

According to the seventh aspect, in the RFID module of the sixth aspect, the coil element and the RFIC chip do not overlap in a planar view on the first main surface side of the substrate. This reduces the influence of the magnetic field induced by the current flowing through the coil element on the RFIC chip.

According to an eighth aspect, the RFID module of the third aspect further includes a first interlayer connection conductor that connects the RFIC chip and the first electrode through the substrate, and a second interlayer connection conductor that connects the RFIC chip and the second electrode through the substrate. The connection point between the first electrode and the coil element is located further outward in the longitudinal direction of the substrate than the connection point between the first electrode and the first interlayer connection conductor, and the connection point between the second electrode and the coil element is located further outward in the longitudinal direction of the substrate than the connection point between the second electrode and the second interlayer connection conductor. This reduces the effect of steps at the connection points between each interlayer connection conductor and electrode on the connection points between the coil element and each electrode.

According to the ninth aspect, in the RFID module of the third or eighth aspect, the coil element has a first coil extension on one side that extends from the connection with the first electrode further outward from the substrate 3, and a second coil extension on the other side that extends from the connection with the second electrode further outward from the substrate 3 in the opposite direction to the extension of the first coil extension. This can improve communication characteristics.

REFERENCE SIGNS LIST 1, 1A RFID module 2 Module 3, 3A Substrate 4, 4A First main surface 5, 5A Second main surface 6, 6A, 6C Coil element 7 RFIC chip 7a Feeding point 8 First terminal 9 Second terminal 10, 10A Resin layer 11 Capacitor 17 Resist layer 18 Resist layer 19, 19A, 19B, 19C First land 21, 21A, 21B, 21C Second land 23 Solder 25 Conductive pattern 27 Electrode 29, 29B First electrode 29Ba Electrode 29Bb Wiring 29Bc Electrode 31, 31B Second electrode 31Ba Electrode 31Bb Wiring 31Bc Electrode 41 Conductive wire 44, 44A First end 44C First connection portion 45, 45A Second end 45C Second connection portion 47 Solder 55, 55B First interlayer connection conductor 57 Second interlayer connection conductor 61 Resist layer 91 Coil element 101 UV curable resin liquid Wa Winding axis

Claims (8)

A substrate;
a first electrode and a second electrode disposed on the substrate;
a coil element connected at one end to the first electrode and at the other end to the second electrode;
an RFIC chip electrically connected to the first electrode and the second electrode;
a first insulating layer covering the RFIC chip;
the coil element is wound around the substrate, and at least a portion of the coil element is exposed to the outside of the first insulating layer ;
The coil element
a first coil extension portion extending from a connection portion with the first electrode on one side to an outside of the substrate;
and a second coil extension portion on the other side extending from the connection portion with the second electrode further outward from the substrate in a direction opposite to the direction in which the first coil extension portion extends.
RFID module. The coil element has a conductive wire wound multiple times,
The winding pitch of the conductor is larger than the wire diameter of the conductor.
The RFID module according to claim 1 . the substrate has a first main surface and a second main surface facing each other,
The RFIC chip is disposed on the first main surface side,
the first electrode and the second electrode are disposed on the second principal surface side,
the first insulating layer is disposed on the first main surface;
a second insulating layer on the second main surface that covers at least a portion of the first electrode and the second electrode;
the coil element is wound around the substrate and the first insulating layer;
The RFID module according to claim 1 . a cross section of the first insulating layer perpendicular to the winding axis of the coil element is rectangular;
The RFID module according to claim 1 . the substrate has a first main surface and a second main surface facing each other,
the RFIC chip, the first electrode, and the second electrode are arranged on the first main surface side;
The RFID module according to claim 1 . The RFIC chip is disposed at the center of the coil element in a longitudinal direction in a plan view.
The RFID module according to claim 1 . On the first main surface side of the substrate, the coil element and the RFIC chip do not overlap in a plan view.
The RFID module according to claim 6 . a first interlayer connection conductor that connects the RFIC chip and the first electrode through the substrate;
a second interlayer connection conductor that connects the RFIC chip and the second electrode through the substrate,
a connection point between the first electrode and the coil element is located outside a connection point between the first electrode and the first interlayer connection conductor in a substrate longitudinal direction;
a connection point between the second electrode and the coil element is located outside a connection point between the second electrode and the second interlayer connection conductor in a substrate longitudinal direction;
The RFID module according to claim 3 .