JP7179264B2 - IC tag - Google Patents

Description

TECHNICAL FIELD The present invention relates to an IC tag, and more particularly to an IC tag having an antenna in which the distribution of resistance values in the antenna pattern is varied.

2. Description of the Related Art RFID, which uses an IC tag that reads and writes information on an IC chip without contact using radio waves, has been widely used. For example, inventory management by attaching IC tags to various articles has become widely practiced. An IC tag is a tag-type electronic device that operates by receiving radio waves from a reader/writer, in which an antenna or the like is connected to an IC chip that stores ID information and the like. Regarding such an IC tag, a flat array antenna and a communication terminal using the flat array antenna and a communication terminal using the same are used to concentrate electromagnetic waves in a specific direction to improve the directivity of the antenna. There is a technology related to wireless modules (Patent Document 1). A flat plate array antenna according to this technology consists of a set of a plurality of micro planar conductor elements distributed within a plane, and in a predetermined length direction with respect to a specific azimuth angle with respect to the normal of the plane, the micro plane A part of the micro planar conductors constitutes a feeding point, and each of the micro planar conductors functions as a radiation conductor and a feeding line of an antenna. The technology can eliminate unnecessary radiation from the feeder line, which is a factor in degrading the characteristics of the array antenna. It is said to have the effect of eliminating the need for a structure for shielding the feeder line. However, even with an IC tag having such an array antenna, it is possible to improve the overall sensitivity when receiving radio waves from a reader/writer with the antenna, while suppressing reflection when transmitting the received radio waves to the IC chip. No consideration has been given to doing

Japanese Patent No. 5086217

In the prior art, the connection between the antenna and the IC chip has not been optimized in terms of suppressing reflections from the IC chip while improving overall sensitivity. In particular, there was no idea to improve the overall electrical properties by varying the resistance value according to position within the antenna. Therefore, there is room for improving the electrical characteristics of IC tags, such as increasing sensitivity and reducing reflection.

The present invention has been made in view of the above problems, and has the following features. That is, the present invention comprises an IC chip, a pair of antennas connected thereto, a first substrate, a second adhesive layer, and respective bonding regions and portions of the pair of peripheral side edges of the antennas. An IC tag in which a set of auxiliary antennas each having a pattern that overlaps in the vertical direction and extends in the peripheral direction around the IC chip, and a second substrate are sequentially laminated, wherein the auxiliary antenna is 0.1 Ω/□ or more and 1 kΩ. It has a surface resistivity of /□ or less, and the auxiliary antenna is characterized in that the surface resistivity is lower in the peripheral region than in the region close to the IC chip. The present invention is a label form in which the cover portion having the first adhesive layer disposed on the cover is further disposed on the upper surface of the IC chip, and the mount portion having the third adhesive layer disposed on the release mount is further disposed on the lower surface of the second substrate. can also be configured. The present invention is a label form in which the cover portion having the first adhesive layer disposed on the cover is further disposed on the lower surface of the second substrate, and the mount portion having the third adhesive layer disposed on the release mount is further disposed on the upper surface of the IC chip. can also be configured. The present invention also allows the auxiliary antenna to be formed by solidifying a conductive ink. In the present invention, the antenna can also be formed by fixing conductive particles containing any one of metal particles, carbon particles, and carbon nanotubes with a resin.

The present invention provides an IC tag in which an IC chip, a set of antennas connected thereto, a set of auxiliary antennas, and a second base material are sequentially laminated, wherein the auxiliary antenna has a resistance of 0.1Ω/□ or more and 1 kΩ. /□ or less surface resistivity. The sensitivity of the antenna is increased by lowering the surface resistivity of the peripheral regions, which are both ends in the longitudinal direction. can be suppressed from being reflected by the IC chip, the reflected current can be reduced, and the standing wave can be minimized.

1 is a schematic plan view of an IC tag having a basic configuration according to the present invention; FIG. 1 is a schematic cross-sectional view of an IC tag having a basic configuration according to the present invention; FIG. 1 is a schematic cross-sectional view of a label-type IC tag according to the present invention; FIG.

The IC tag 100 according to the present invention is a tag-type electronic device that operates by receiving radio waves. It is a tag-type electronic device in which an IC chip, an antenna, a base material, etc. are laminated, and which can read and transmit stored ID information. The IC tag 100 has a basic structure having a shape and operation as an IC tag, but is further laminated on both sides so as to sandwich a cover portion and a mount portion, and is a label-type IC tag that can be attached to a product or the like. It can also be 100A.

FIG. 1 shows a schematic plan view of an IC tag 100 having a basic configuration, and FIG. 2 shows a schematic cross-sectional view of the IC tag 100 having a basic configuration. FIG. 2 is a cross-sectional view taken along the line A-A' in FIG. 1 when the arrow direction is viewed from the position along the line A-A'. Although FIG. 2 shows the order of stacking each layer, the shape of the cross section is an outline and does not accurately represent the actual cross section. In addition, the space between each layer in FIG. 2 may actually be filled by the layers above and below the space being in close contact with each other. The upper direction in FIG. 2 is the direction opposite to the sticking surface when the IC tag 100 is stuck to the product. Define 100 downwards. The IC tag 100 typically has a basic structure in which an IC chip 103, an antenna 104, a first base material 105, a second adhesive layer 106, an auxiliary antenna 107, and a second base material 108 are laminated in that order. .

A configuration of the IC tag 100 having a basic configuration will be described. The IC chip 103 is an integrated circuit chip that stores ID information and the like, and is a component that outputs the ID information by sending a command there. Also, the IC chip 103 can preferably store other information or rewrite ID information or the like by sending commands and write data to it. The output of the ID information is preferably output as a high-frequency signal containing the information and can be transmitted contactlessly. Note that the IC chip 103 can also be a circuit in which an integrated circuit having a function related to data storage and a high-frequency circuit are combined. IC chip 103 has a set of antenna contacts (not shown), typically two, which are electrical contacts with antenna 104 . The antenna contact and the antenna 104 are conductively adhered with ACP (anisotropic conductive paste) or the like. The IC chip 103 acquires the radio signal received by the antenna 104 through the antenna contact, obtains driving power therefrom, and acquires and executes information such as a command included in the radio signal. If the command is a command for outputting ID information, the IC chip 103 reads out the stored ID information, generates a high frequency wave containing the information, and transmits reflected waves from the antenna 104 and the auxiliary antenna 107 via the antenna contact. output as

Antenna 104 is an element for receiving electromagnetic waves from an external reader and transmitting reflected waves thereto. Antenna 104 contacts a set of antenna contacts on the lower surface of IC chip 103 at its central end, extends laterally around IC chip 103 in the peripheral direction, and has a set of contact points at each end on the peripheral side. It is formed of a conductive material having a pattern with bonding areas. The antenna 104 is typically formed by fixing conductive particles such as metal particles, carbon particles, and carbon nanotubes with a resin to form a predetermined pattern shape and thickness. The conductive particles are kneaded into a resin or resin binder dissolved in a solvent to form a conductive paste, arranged in a predetermined pattern, and then the solvent is evaporated to solidify the conductive particles in a predetermined pattern. Alternatively, the conductive particles can be kneaded into a thermosetting resin or an ultraviolet curable resin to form a conductive paste, arranged in a predetermined pattern, and then solidified into a predetermined pattern by heat or ultraviolet rays. The pattern can be easily formed by printing or printing with a printer. Antenna 104 is typically formed from a material that is more conductive than auxiliary antenna 107, which will be described later. Antenna 104 preferably forms part of a half-wave dipole, in which case the pattern is a pair of dipoles extending laterally (right and left) in the peripheral direction with each of the two antenna contacts as the central end. It is a linear pattern. That is, the patterns of the antenna 104 extending from the left and right to the lower surface of the IC chip 103 in FIG. It is connected with each of the antenna contacts. At the peripheral edge of the pattern, there is a bonding area of a planar pattern having a certain area (in FIG. 1, a rectangular pattern at the edge of a linear pattern extending left and right). It is capacitively coupled with a partial area of a pair of auxiliary antennas 107 facing each other with the base material 105 and the second adhesive layer 106 interposed therebetween. And typically, the antenna 104 and the auxiliary antenna 107 are electrically integrated to form a half-wave dipole. In the pattern shown in FIG. 1, the linear pattern extending to the left and right branches downward at a position slightly closer to the center than the connecting region, and the left and right branch patterns are connected to form a loop pattern. is doing. This loop-shaped pattern has an inductance component and forms part of a matching circuit for efficiently coupling the IC chip 103, the antenna 104, the auxiliary antenna 107, and the like. Note that this loop pattern is not always essential. Antenna 104 (and auxiliary antenna 107 capacitively coupled thereto) is typically a half-wave dipole, but can be any antenna configuration capable of transmitting and receiving electromagnetic waves.

The first base material 105 is a sheet placed on the lower surface of the antenna 104 to hold it flat. The first base material 105 is composed of a plastic sheet or the like. The first base material 105 can have, for example, a rectangular shape slightly larger than the antenna 104 . The second adhesive layer 106 is a sheet-like adhesive that is placed on the lower surface of the first base material 105 for bonding the first base material to the auxiliary antenna 107 and the second base material 108 on the lower surface. The adhesive in the present invention may be one that solidifies after bonding or one that does not solidify after bonding (adhesive).

Auxiliary antenna 107 is arranged on the lower surface of second adhesive layer 106 and extends in the peripheral direction centering on IC chip 103 while partially overlapping each of the pair of coupling regions at the peripheral edge of antenna 104 in the vertical direction. A set of planar patterns formed of a conductive material, each having a pattern. In the area where the auxiliary antenna 107 vertically overlaps the coupling area at the peripheral edge of the antenna 104, they are capacitively coupled. Auxiliary antenna 107 is typically integrated with antenna 104 to form a half-wave dipole. The area of the pattern of the auxiliary antenna 107 is considerably larger than the area of the pattern of the antenna 104 and occupies most of the area of the IC tag 100 . Therefore, the auxiliary antenna 107 can efficiently transmit and receive electromagnetic waves, and can transmit such electromagnetic waves to the antenna 104 through capacitive coupling. Auxiliary antenna 107 is typically formed by solidifying a conductive ink on second substrate 108 . Conductive ink is obtained by dispersing conductive particles in a binder dissolved in a solvent, and after arranging it in a predetermined pattern, the conductive particles can be solidified in a predetermined pattern by evaporating the solvent. The solidified conductive ink may have slightly lower conductivity than the solidified conductive paste forming the antenna 104, but it is preferable to use an inexpensive material. For that purpose, for example, inexpensive conductive particles can be used, or the proportion of the binder can be increased. Pattern formation using conductive ink can be easily performed by printing or a printer. Therefore, by forming the auxiliary antenna 107 by solidifying the conductive ink, it is possible to form an antenna pattern with a large area easily and inexpensively. If the area of the antenna pattern is large, the sensitivity of the IC tag 100 to electromagnetic waves can be increased. Auxiliary antenna 107 is preferably formed to have a surface resistivity (sheet resistance) of 0.1 Ω/sq. be. If the surface resistivity is within this range, it is possible to transmit and receive electromagnetic waves without any problem, and at the same time, it is possible to form the substrate at a low cost.

The auxiliary antenna 107 has a substantially rectangular pattern shape when viewed from the top and bottom direction of the IC tag 100, but the thickness when viewed from the cross-sectional direction is such that the peripheral area is closer to the IC chip and the center side. is formed to have a thicker profile than the region of In the plan view of FIG. 1, the peripheral area of the auxiliary antenna 107 is darker and the area closer to the IC chip is lighter. The darker the color, the thicker the antenna. FIG. 2 shows a cross section of the antenna portion viewed from line A-A' in FIG. It should be noted that the shape of the cross section in FIG. 2 is an outline and does not accurately represent the actual shape. Here, the cross section of the auxiliary antenna 107 shows that the area on the peripheral side is thick and the area close to the IC chip is thin. Unlike etching, the thickness profile can be freely set when the conductive ink is printed and solidified after being printed by a printer, so that such a profile with a thick peripheral region can be easily formed. In other words, a larger amount of conductive ink may be printed or adhered onto the second substrate 108 at the time of printing where the thickness is to be increased. For printing, various known printing methods (letterpress printing, offset printing, on-demand printing, etc.) can be used. In order to control the thickness of the conductive ink in printing, various well-known techniques for expressing densities can be used. For example, by forming a pattern with a large number of halftone dots and controlling the size of each halftone dot, the conductive ink can be printed with different shades. In the case of printing by a printer, various known printing methods (ink jet, thermal transfer, etc.) can be used. In order to control the thickness of the conductive ink, various known techniques for representing shading in printing can be used. For example, in the case of inkjet printing, the conductive ink can be printed with different densities by changing the amount of ink ejected per unit area.

Since the auxiliary antenna 107 has a profile in which the area on the peripheral side is thicker than the area close to the IC chip, the surface resistivity (resistance per unit width and unit length) is increased in the area close to the IC chip. The area on the side of the IC chip is lower than the area close to the IC chip, and the current flows more easily in the area on the peripheral side. It is preferable that the surface resistivity of the peripheral region is 10% or more lower than the surface resistivity of the region adjacent to the IC chip. When the IC tag 100 receives an electromagnetic wave from a reader/writer, a main electric charge is induced in the large-area auxiliary antenna 107 and transmitted to the IC chip 103 via the antenna 104 . Here, first, both ends of the entire antenna including the auxiliary antenna 107 and the antenna 104 in the longitudinal direction are areas on the peripheral side of the auxiliary antenna 107, but since the surface resistance value there is small, the received electromagnetic waves are It can be efficiently converted into an electric charge. Since the impedance matching among the auxiliary antenna 107, the antenna 104, and the IC chip 103 is not necessarily perfect, reflection occurs due to impedance discontinuity at their connection portions. If the surface resistivity of the auxiliary antenna 107 does not change depending on the position and is constant, the current due to the charge induced in the auxiliary antenna 107 tries to flow into the IC chip 103 as it is. Then, since the reflection is considered to be proportional to the value of the current, reflection corresponding to the value of the current occurs at the impedance discontinuity. This can lead to adverse effects due to reflected waves. However, by configuring the auxiliary antenna 107 so as to have such a profile that the area on the peripheral side is thick and the area close to the IC chip is thin, electric charges are induced in the auxiliary antenna 107 upon receiving electromagnetic waves from the reader/writer. In this case, the resistance in the vicinity of the impedance discontinuity increases, making it difficult for a large current to flow there. As a result, reflection at the connecting portion between the auxiliary antenna 107, the antenna 104, and the IC chip 103 is less likely to occur, and adverse effects caused by reflection can be reduced. In this way, by configuring the auxiliary antenna 107 so that the surface resistivity of the peripheral area is lower than that of the area close to the IC chip, electric charges are easily induced near both ends of the entire antenna, thereby increasing the sensitivity of the entire antenna. By limiting the current flowing through the connecting portion while increasing the , the reflection can be suppressed, and the adverse effect of the reflection can be suppressed.

The second base material 108 is a sheet placed on the lower surface of the auxiliary antenna 107 to hold it flat. The second base material 108 is composed of a plastic sheet or the like. The second base material 108 has a rectangular shape with substantially the same shape and area as the IC tag 100 when viewed from above and below. The IC tag 100 having the basic configuration is formed by stacking the IC chip 103 to the second base material 108 in the order described above.

Next, the label type IC tag 100A will be described. When the IC tag 100 is in the form of a label that can be adhered to a product, in addition to the above-described basic structure in which the IC chip 103 to the second base material 108 are laminated, an upward A label is formed by laminating a cover portion consisting of a cover 101 and a first adhesive layer 102 when viewed from above, and laminating a mount portion consisting of a third adhesive layer 109 and a release mount 110 when viewed from above on the lower surface thereof. Additional lamination for morphology is done.

FIG. 3 shows a schematic cross-sectional view of an IC tag 100A in the form of a label. Although FIG. 3 shows the order of stacking each layer, the shape of the cross section is an outline and does not accurately represent the actual cross section. In addition, the space between each layer in FIG. 3 may actually be filled by the layers above and below the space being in close contact with each other. An IC tag 100 having a basic configuration is additionally laminated so as to be sandwiched between a cover portion where the first adhesive layer 102 is arranged on the cover 101 and a mount portion where the third adhesive layer 109 is arranged on the release mount 110. Thus, the IC tag 100A includes a cover 101, a first adhesive layer 102, an IC chip 103, an antenna 104, a first base material 105, a second adhesive layer 106, an auxiliary antenna 107, a second base material 108, and a third adhesive layer 109. , the structure in which the release mount 110 is laminated in that order (or, the cover part and the mount part are turned upside down with respect to the IC tag 100 part of the basic structure from the IC chip 103 to the second base material 108, Release mount 110, third adhesive layer 109, IC chip 103, antenna 104, first base material 105, second adhesive layer 106, auxiliary antenna 107, second base material 108, first adhesive layer 102, cover sheet 101) It has the structure laminated|stacked in the order. With this configuration, it is possible to function as a label-type IC tag that can be attached to a product or the like.

Specifically, on the upper surface of the IC chip 103, a sheet for bonding the IC chip 103 to the cover 101 together with the upper surfaces of the antenna 104, the first base material 105, the auxiliary antenna 107, the second base material 108, etc., having a larger area than that of the IC chip 103, is provided. A first adhesive layer 102 is disposed. Then, the cover 101 is adhered to the top surface by the first adhesive layer 102 . The cover 101 is a sheet of paper, a plastic sheet, or the like, and serves as the uppermost surface of the IC tag 100 in the form of a label to protect the inside. The cover 101 and the first adhesive layer 102 have substantially the same shape as the IC tag 100 when viewed from above and below. Cover 101 is adhered to the upper surfaces of IC chip 103, antenna 104, first base material 105, auxiliary antenna 107, second base material 108, etc. by first adhesive layer 102, thereby bonding IC chip 103, antenna 104, and second base material 108 together. 1 Base material 105, auxiliary antenna 107, etc. are enclosed in a pouch to protect the inside.

Furthermore, a third adhesive layer 109, which is a sheet-like adhesive, is arranged on the lower surface of the second base material 108 to releasably adhere the second base material 108 to the release liner 110 on the lower surface. Then, the release mount 110 is releasably adhered to the bottom surface by the third adhesive layer 109 . The third adhesive layer is an adhesive that does not harden after adhesion, and can be adhered to a product or the like after peeling off the release liner 110 . The release mount 110 is a release agent-coated mount that detachably holds the label-shaped IC tag 100, and is peeled off and discarded when the IC tag 100 is attached to a product. The release liner 110 may be larger than the IC tag 100 when viewed from the top and bottom direction, and may be tape-shaped or sheet-shaped, for example, and may be shaped to hold a plurality of IC tags 100 thereon. In this manner, a label-type IC tag 100A that can be attached to a product or the like after being peeled off from the release mount 110 is constructed.

In addition, in the case of the IC tag 100A having a configuration in which the cover portion and the mount portion are turned upside down with respect to the IC tag 100, the IC chip 103 is placed on the top surface of the IC chip 103, the antenna 104 having a larger area, and the first base. A third adhesive layer 109, which is a sheet-like adhesive, is arranged to releasably adhere to the release board 110 together with the top surface of the material 105, the auxiliary antenna 107, the second base material 108, and the like. is releasably adhered to the uppermost surface by a third adhesive layer 109, and the first adhesive layer 102 for adhering to the cover 101 is arranged on the lower surface of the second base material 108, and the cover 101 is further attached to the lowermost surface. placed.

INDUSTRIAL APPLICABILITY The present invention can improve electrical characteristics such as sensitivity and reflection of IC tags and label-type IC tags used in RFID, and can be suitably applied to them.

100: IC tag (basic configuration)
100A: IC tag (label form)
101 : Cover 102 : First adhesive layer 103 : IC chip 104 : Antenna 105 : First substrate 106 : Second adhesive layer 107 : Auxiliary antenna 108 : Second substrate 109 : Third adhesive layer 110 : Release mount

Claims (5)

an IC chip;
A pattern having a pair of coupling regions on each of the peripheral side edges, each of which is in contact with a pair of antenna contacts on the lower surface of the IC chip and extends horizontally around the IC chip in a peripheral direction. an antenna formed of a conductive material having
a first substrate disposed on the lower surface of the antenna and holding the antenna;
a second adhesive layer disposed on the lower surface of the first substrate for adhesion;
It is arranged on the lower surface of the second adhesive layer and formed of a conductive material having a pattern that partially overlaps with each of the coupling regions of the antenna in the vertical direction and extends in the peripheral direction around the IC chip. a pair of auxiliary antennas;
a second base material arranged on the lower surface of the auxiliary antenna and holding the auxiliary antenna; and a laminated IC tag,
The auxiliary antenna has a surface resistivity of 0.1 Ω/□ or more and 1 kΩ/□ or less,
The auxiliary antenna has a lower surface resistivity in a peripheral area than in an area close to the IC chip.
An IC tag characterized by: a first adhesive layer disposed on the upper surface of the IC chip for adhesion;
a cover arranged on the upper surface of the first adhesive layer;
a third adhesive layer disposed on the lower surface of the second substrate for adhesion;
2. The IC tag according to claim 1, further comprising a release backing sheet disposed on the lower surface of said third adhesive layer and releasably adhered to said third adhesive layer to form a label. a third adhesive layer disposed on the upper surface of the IC chip for adhesion;
a release liner disposed on the upper surface of the third adhesive layer and releasably adhered to the third adhesive layer;
a first adhesive layer disposed on the lower surface of the second substrate for adhesion;
2. The IC tag according to claim 1, wherein a cover disposed on the lower surface of said first adhesive layer is further laminated to form a label. 4. The IC tag according to any one of claims 1 to 3, wherein said auxiliary antenna is formed by solidifying conductive ink. 5. The IC tag according to any one of claims 1 to 4, wherein said antenna is formed by fixing conductive particles containing any one of metal particles, carbon particles and carbon nanotubes with resin.

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