JP5172762B2 - Antenna circuit, IC inlet, IC tag, and capacity adjustment method of antenna circuit - Google Patents

Description

  The present invention relates to an antenna circuit, an IC inlet, an IC tag, and a capacity adjustment method for the antenna circuit.

  In recent years, non-contact type IC tags that are attached to a person to be managed or a product (adhered body) and manage distribution and the like of the management object have become widespread. This non-contact type IC tag can store data in a built-in IC chip, and can exchange data to be managed with an interrogator by communicating with the interrogator in a non-contact manner via radio waves.

  Fields of use of non-contact type IC tags are diverse, such as, for example, commuter pass for various transportation facilities, management of people in and out of a company building, inventory management of goods, logistics management, and the like. There are various types according to these fields of use.

  The non-contact type IC tag mainly includes an IC chip and an antenna circuit. The resonance frequency (f) of an IC tag composed of an IC chip and an antenna circuit is mainly determined by the capacitance (C) of the IC chip and the inductance (L) of the antenna circuit. The relationship is represented by the following formula (1).

f = 1 / {2π (LC) ^1/2 } (1)

  From the above equation (1), in order to adjust the resonance frequency f, at least one of the capacitance (C) and the inductance (L) must be adjusted. In an IC tag, the capacitance is usually a value unique to the IC chip. In order to change the capacitance of the entire IC tag, the capacitance (C) must be corrected on the antenna circuit side. Further, in order to change the inductance (L) of the IC tag, it is necessary to increase or decrease the number of turns of the antenna circuit or change the circuit length.

  Conventionally, the following has been proposed as a method of adjusting the resonance frequency of such an IC tag. For example, in Patent Document 1, a plurality of short-circuited one side of the loop and a branch wiring branching from a side adjacent to the one side of the innermost loop of the antenna coil configured by a rectangular loop of one turn or more A technique is disclosed in which trimming wirings are formed substantially in parallel and the trimming wirings are sequentially cut to adjust the inductance of the antenna coil.

  In Patent Document 2, a first electrode pattern is formed on one surface of a base material, and a second electrode pattern including comb-shaped electrodes is formed on a bridge circuit disposed on the other surface of the base material. A technique is disclosed in which the capacitor is formed by the first electrode pattern, the base material, and the second electrode pattern, and the resonance frequency is adjusted by trimming the comb-shaped electrode.

Japanese Patent No. 3781109 Japanese Patent No. 4016261

  However, in Patent Document 1, since it is necessary to increase the area of the coil portion, there is a problem that the effect is small when the circuit size is small, and the resonance frequency cannot be adjusted with high accuracy. Moreover, since the patent document 2 uses a double-sided wiring pattern, there is a problem in that it cannot be manufactured at low cost because the number of steps for making both sides of the circuit conductive is increased.

  The present invention has been made in view of the above problems, and provides an antenna circuit, an IC inlet, an IC tag, and an antenna circuit capacity adjustment method capable of adjusting the resonance frequency with low cost and high accuracy. For the purpose.

  In order to solve the above-described problems and achieve the object, an antenna circuit according to the present invention comprises an antenna wiring formed by opening a conductive material in a loop shape at both ends, and an electronic component at both ends of the antenna wiring. An antenna portion that forms a closed circuit when connected, and a capacitance adjustment wiring that is provided outside the closed circuit and that has one end connected to the antenna wiring and formed along the antenna wiring. It is characterized by having.

  Moreover, the antenna circuit according to the present invention is characterized in that the capacitance adjusting wiring is formed on at least one of the inside, the outside, and the wiring of the antenna wiring.

  The IC inlet according to the present invention includes the antenna circuit and electronic components connected to both ends of the antenna wiring.

  In addition, an IC tag according to the present invention includes the IC inlet.

  Further, in the antenna circuit capacity adjustment method according to the present invention, the antenna circuit is composed of an antenna wiring in which a conductive material is formed in a loop shape with both ends open, and electronic components are connected to both ends of the antenna wiring. An antenna portion that forms a closed circuit in the case, and a capacitance adjusting wiring that is provided outside the closed circuit and has one end connected to the antenna wiring and formed along the antenna wiring, The capacity of the antenna circuit is adjusted by changing the length of the capacity adjustment wiring.

  According to the present invention, an antenna circuit, an IC inlet, an IC tag, and an antenna that can adjust the capacity of the antenna circuit with low cost and high accuracy and can adjust the resonance frequency with low cost and high accuracy. The circuit capacity adjustment method can be provided.

FIG. 1-1 is a plan view showing a configuration of an antenna circuit according to the present embodiment. 1-2 is a diagram showing a cross-sectional configuration of the antenna circuit of FIG. 1-1 along the line AA. FIG. 2-1 is a plan view showing the configuration of the IC inlet according to the present embodiment. FIG. 2B is a diagram illustrating a cross-sectional configuration of the IC inlet of FIG. FIG. 3 is a diagram showing an equivalent circuit of the IC inlet of FIG. 2-1. FIG. 4A is a cross-sectional view illustrating an example of an IC adhesive label. FIG. 4B is a cross-sectional view of another example of the IC adhesive label. FIG. 5A is a cross-sectional view illustrating an example of an IC card. FIG. 5B is a cross-sectional view illustrating another example of the IC card. FIG. 6A is a plan view illustrating a configuration of a comparative example of the IC inlet. FIG. 6B is a plan view illustrating the configuration of the IC inlet according to the first embodiment. FIG. 6-3 is a plan view illustrating the configuration of the IC inlet according to the second embodiment. FIG. 6-4 is a plan view showing the configuration of the third embodiment of the IC inlet. 6-5 is a top view which shows the structure of Example 4 of an IC inlet. FIG. 7 is a diagram illustrating a modification of the arrangement position of the adjustment coil. FIG. 8 is a diagram illustrating a modification of the arrangement position of the adjustment coil. FIG. 9 is a diagram showing a modification of the shape of the planar coil of the antenna circuit.

  Hereinafter, embodiments of an antenna circuit, an IC inlet, an IC tag, and a capacity adjustment method for an antenna circuit according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or that are substantially the same.

  The antenna circuit according to the present embodiment is composed of an antenna wiring formed of a conductive material in a loop shape with both ends open, and is closed when an electronic component (for example, an IC chip) is connected to both ends of the antenna wiring. An antenna portion (for example, a planar coil) that forms a circuit, and a capacitance adjusting wiring (for example, a wiring that is provided outside the closed circuit and that has one end connected to the antenna wiring and formed along the antenna wiring. Adjustment coil), and a desired resonance frequency can be obtained by changing the length of the capacitance adjustment wiring.

(Antenna circuit, IC inlet)
1-1 is a plan view showing a schematic configuration of an antenna circuit according to an embodiment of the present invention. FIG. FIG. 1-2 is a diagram illustrating a cross-sectional configuration along the line AA in FIG. 1-1. FIG. 2-1 is a plan view illustrating a schematic configuration of the IC inlet according to the present embodiment. FIG. 2B is a diagram illustrating a cross-sectional configuration along the line AA in FIG. FIG. 3 is a diagram showing an equivalent circuit of the IC inlet of FIG. 2-1.

  1-1 and FIG. 1-2, the antenna circuit 1 includes a planar coil (antenna portion) 12, pads 13a and 13b, a jumper 14, an insulating resist 18, an IC on a circuit base material 11. The chip mounting connector 15, an external capacitor 16, and an adjustment coil 17 (capacitance adjustment wiring) are provided. The antenna circuit 1 is an open circuit, and becomes a closed circuit when an IC chip is mounted on the IC chip mounting connector 15.

  2A and 2B, the IC inlet 2 has an IC chip 21 (electronic component) mounted on the IC chip mounting connector 15 of the antenna circuit 1 shown in FIGS. 1-1 and 1-2. State circuit. In the present embodiment, the case where one IC chip 21 is provided in a single antenna circuit 1 is illustrated, but a plurality of IC chips 21 may be mounted.

  The IC chip 21, which is an electronic component, stores data such as a code unique to the ID tag, and performs a transmission operation of the stored data by receiving an interrogation radio wave from an interrogator (not shown). Is. The energy required for such transmission / reception processing by the IC chip 21 includes the inductance (L component) of the planar coil 12 and the capacitance (C component) of the IC chip 21, the external capacitor 16, the adjustment coil 17, and the like. ) Is obtained from the interrogation radio wave due to resonance.

  As the circuit substrate 11, a sheet material such as a synthetic resin film such as polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride, polyimide, or polycarbonate, or a paper material such as fine paper, coated paper, glassine paper, or non-woven fabric is used. it can. Although the thickness of the circuit base material 11 is not specifically limited, 5-300 micrometers is preferable and 10-200 micrometers is especially preferable.

  The planar coil 12 forming the antenna unit mainly has an antenna function and a power supply function. The planar coil 12 is an antenna wiring in which a conductive material is formed in a loop shape (annular) with both ends open, and has a substantially circular shape. For the planar coil 12, a method of winding a coated copper wire in a coil shape, a method of printing a conductive paste in a coil shape, and forming a conductive metal layer such as a copper foil laminated on the circuit substrate 11 into a coil shape by etching It can form by the method of doing. As the conductive paste, a paste in which metal particles such as gold, silver and nickel are dispersed in a binder can be used. Moreover, as a binder, a polyester resin, a polyurethane resin, an epoxy resin, etc. are applicable. The number of turns, the line width, and the distance between the planar coils 12 can be arbitrarily set according to acquisition of a desired resonance frequency.

  The end portion (outermost end portion) located outside the planar coil 12 is one side of the IC chip mounting connector 15 located inside the planar coil 12 via the pad 13a, the jumper 14 and the pad 13b. Connected to the electrode section. Further, an end portion (innermost end portion) located inside the planar coil 12 is connected to the other electrode portion of the IC chip mounting connector 15. As the pads 13a and 13b, for example, a metal such as copper or aluminum, or a conductive material such as conductive ink such as silver paste can be used.

  The jumper 14 is for making an electrical connection between the outer end and the inner end of the planar coil 12. As the jumper 14, for example, a conductive paste or conductive ink in which metal particles such as gold, silver, and nickel are dispersed can be applied.

  An insulating resist 18 is disposed below the jumper 14. The insulating resist 18 provides insulation between the jumper 14 and each loop of the planar coil 12. As the insulating resist 18, for example, an insulating resin whose main component is an acrylic resin, a urethane resin, an acrylic urethane resin, or the like can be applied. In addition, a through-hole is formed in the circuit base material 11 at the position where the pads 13a and 13b of the circuit board 11 are formed, and the jumper 14 is a surface opposite to the surface on which the planar coil 12 is formed in the circuit base material 11. It is good also as a structure which is drawn around and makes the pad 13a and 13b conduct | electrically_connect. Thereby, when adjusting the length of the coil 17 for adjustment, a process may become easy.

  The IC chip mounting connector 15 includes a pair of electrode portions for mounting the IC chip 21. As the electrode portion of the IC chip mounting connector 15, for example, a metal such as copper or aluminum, or a conductive material such as conductive ink such as silver paste can be applied.

  When the IC chip 21 is mounted on the electrode portion of the IC chip mounting connector 15, the IC chip 21 is connected to the electrode portion of the IC chip mounting connector 15 using a connecting material. As the connecting material, solder, anisotropic conductive adhesive, anisotropic conductive adhesive film, and the like can be applied. As the anisotropic conductive adhesive and the anisotropic conductive adhesive film, those mainly composed of an epoxy resin in which metal particles or the like are dispersed can be used.

  The external capacitor 16 is connected in parallel to a closed circuit formed by the antenna circuit 1 and the IC chip 21. Specifically, the external capacitor 16 is connected between the pad 13b and the innermost end of the planar coil 12. Yes. The capacity of the external capacitor 16 can be arbitrarily set according to acquisition of a desired resonance frequency. In the present embodiment, the external capacitor 16 is not necessarily an essential component, and is unnecessary when the capacitance can be adjusted only by the adjustment coil 17.

  The adjustment coil 17, which is a capacitance adjustment wiring, is for adjusting the C component of the resonance frequency of the IC inlet 2, and is provided outside the closed circuit formed by the planar coil 12 and the IC chip 21, In addition, one end side thereof is connected to the planar coil 12 and is formed along the planar coil 12, and the other end side is not connected to the planar coil 12. The adjustment coil 17 forms a capacity with the adjacent planar coil 12. The length, position, number, line width, and line spacing of the adjustment coil 17 can be arbitrarily set according to acquisition of a desired resonance frequency. For the adjustment coil 17, for example, the same material as that of the planar coil 12 can be used.

  Here, when the inductance of the planar coil 12 is L, the capacitance of the IC chip 21 is C1, the capacitance of the external capacitor 16 is C2, and the stray capacitance formed by the adjustment coil 17 is C3, the IC inlet 2 can be represented by the equivalent circuit of FIG. Further, the resonance frequency (f) of the IC inlet 2 can be expressed by the following expression (2).

f = 1 / {2π (L (C1 + C2 + C3)) ^1/2 } (2)

  As can be seen from the above equation (2), the resonance frequency f can be lowered by increasing the capacitance C3 formed by the adjustment coil 17, and the resonance frequency f can be increased by reducing the capacitance C3. Can do.

  In the present embodiment, a desired resonance frequency can be obtained by adjusting the capacitance formed by the adjustment coil 17 by changing the length of the adjustment coil 17. As a method of adjusting the length of the adjustment coil 17, for example, (1) without adjusting coil 17 being formed in the antenna circuit 1, the adjustment of the length necessary for obtaining a desired resonance frequency later There are a method of forming the coil 17 and (2) a method of forming the adjustment coil 17 longer in the antenna circuit 1 and cutting the adjustment coil 17 to obtain a desired resonance frequency later.

(IC tag)
Next, the configuration of the IC tag of this embodiment will be described with reference to the drawings. In the present specification and claims, an IC tag includes an IC adhesive label and an IC card, and refers to an IC inlet that has been subjected to predetermined processing, and the IC inlet is sealed with resin. An IC sealing body is also included. Hereinafter, an example in which the IC inlet according to the present embodiment is processed into an IC adhesive label and an IC card will be described.

[IC adhesive label]
FIG. 4A is a cross-sectional view illustrating an example of an IC adhesive label. In the figure, an IC adhesive label 3 has an adhesive layer 31 formed on the upper surface of the IC inlet 2 shown in FIG. 2-2 so as to cover the planar coil 12, the adjustment coil 17, the IC chip 21 and the like. A release material 32 is detachably attached to the upper surface of the adhesive layer 31. In the present specification, the adhesive is a concept including a normal adhesive and a pressure-sensitive adhesive. In addition, as the adhesive layer 31, a film, paper, a nonwoven fabric, or the like may be used as the core, and an adhesive layer having an adhesive layer on both surfaces of the core may be used.

  The adhesive layer 31 has a function of covering the IC chip 21 and the antenna circuit 1 and embedding them in the adhesive layer 31 so as to follow these irregularities and sealing them. As the adhesive layer 31, a known adhesive can be used without limitation, and specifically, an acrylic adhesive, a urethane adhesive, a natural rubber or a synthetic rubber adhesive, a silicone resin adhesive, Examples include polyolefin adhesives, polyester adhesives, ethylene-vinyl acetate adhesives, and the like.

For example, it can be formed by applying the adhesive layer 31 on the release treatment surface of the release material 32 and then bonding the adhesive layer 31 to the circuit formation surface of the IC inlet 2. The coating amount of the adhesive is preferably ^{5~300g / m 2, 10~100g / m} 2 is particularly preferred.

  A known material can be used as the release material 32. For example, films made of various resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene, polypropylene, polyethylene laminated paper, polypropylene laminated paper, clay coated paper, resin Various paper materials such as coated paper and glassine paper can be used as the base material, and the surface of the base material bonded to the adhesive layer can be peeled off if necessary. In this case, a representative example of the form subjected to the release treatment includes formation of a release agent layer made of a release agent such as a silicone resin, a long-chain alkyl resin, or a fluorine resin. The thickness of the release material is not particularly limited and may be appropriately selected.

  Next, a method for using the IC adhesive label 3 will be described. First, the release material 32 of the IC adhesive label 3 is peeled off from the adhesive layer 31, and the IC adhesive label 3 is attached to an adherend (not shown) that is a data management object. As a result, the IC tag 3 can be used, and by exchanging data with the interrogator, various types of management of the adherend can be performed.

  FIG. 4B is a cross-sectional view of another example of the IC adhesive label. In FIG. 4B, the same parts as those in FIG. In the example shown in FIG. 4B, the IC adhesive label 3 has an adhesive layer 33 formed on the surface opposite to the antenna circuit forming surface of the circuit base 11 of the IC inlet 2. The surface base material 34 is stuck. The material of the adhesive layer 33 can be the same as that of the adhesive layer 31.

  The surface base material 34 is preferably capable of printing visible information such as a trade name, and is not particularly limited as long as it is suitable for printing on the surface. For example, a synthetic resin film, synthetic paper, non-woven fabric, paper, or a surface on which various recording layers for thermal recording, pressure-sensitive recording, thermal transfer recording, laser light recording, and inkjet recording are formed may be used.

[IC card]
The IC inlet of the present invention can also be configured in the form of a non-contact type IC card. FIG. 5A is a cross-sectional view illustrating an example of an IC card. In the example shown in FIG. 5A, the IC card 4 is formed by sealing the planar coil 12, the adjustment coil 17, the IC chip 21 and the like of the IC inlet 2 shown in FIG. It is formed into a shape. This resin layer 41 functions as a surface protective layer of the IC inlet 2.

  The resin layer 41 can be formed by, for example, injection molding. The injection molding conditions themselves are known. The resin used for the resin layer 41 is preferably polyethylene terephthalate, polycarbonate, polyacrylonitrile-butadiene, polyethylene, polypropylene, acrylonitrile-butadiene-styrene copolymer, or the like.

  Examples of the use of the IC card 4 include cash cards, credit cards, membership cards, employee cards, entrance / exit management cards, and commuter passes.

  FIG. 5B is a cross-sectional view illustrating another example of the IC card. In FIG. 5B, the same parts as those in FIG. In the example shown in FIG. 5B, the IC card 4 is formed in the form of a card in which the IC inlet 2 shown in FIG. 2B is enclosed in two surface base materials 42 and 43 to which the peripheral edge portion 44 is bonded. Has been. Examples of the bonding method of the peripheral edges 44 of the surface base materials 42 and 43 include heat bonding and bonding methods using various adhesives.

  The surface substrates 42 and 43 are not particularly limited, but paper such as high-quality paper and coated paper, synthetic resin films, and the like are preferable. Resin materials constituting the synthetic resin film include polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyester, polyvinyl acetate, polybutene, polyacrylate ester, polymethacrylate ester, polyacrylonitrile, polyimide, polycarbonate, polyamide, ethylene- Examples include vinyl acetate copolymer, polyvinyl acetal, polyethylene terephthalate, acrylonitrile-butadiene-styrene copolymer, and the like. 10-500 micrometers is preferable and, as for the thickness of a surface base material, 50-400 micrometers is especially preferable.

(IC inlet and IC tag manufacturing method)
Next, an example of a method for manufacturing the IC inlet 2 and the IC tag (IC adhesive label 3, IC card 4) according to the present embodiment will be described.

  The IC tag according to the present embodiment can be manufactured generally by the first to fifth steps described below. In the following manufacturing method, a case will be described in which the length of the adjustment coil 5 for obtaining a desired resonance frequency is known in advance by an experiment before manufacturing.

  First step (conductive layer forming step): On the sheet material to be the circuit substrate 11, the planar coil 12, the pads 13a and 13b, the IC chip mounting connector 15 and the external capacitor 16 (on the antenna circuit 1) ( Conductive portion) and a conductive layer made of adjustment coil 5 having a predetermined length for obtaining a desired resonance frequency are simultaneously formed.

  The conductive layer is formed by a method of bonding a copper foil or aluminum foil previously formed into a predetermined coil shape on the circuit substrate 11 by punching or the like through an adhesive layer (not shown), or the circuit substrate 11. Forming method in which a metal layer is formed on the top by, for example, ion plating, vapor deposition, etc., etching resist printing by screen printing or the like is performed on the metal layer, and the exposed portion is etched to form a coil shape Alternatively, a forming method such as formation by screen printing or the like can be applied to a predetermined coil shape using a metal paste such as silver paste, and the type of conductive material is not limited. In addition, in the formation method of a conductive layer, you may use the thing by which the contact bonding layer was produced previously in copper foil, aluminum foil, etc.

  Second step (insulating layer forming step): An insulating layer to be the insulating resist 18 of the antenna circuit 1 is formed so as to cover the upper surfaces of the planar coil 12 and the adjustment coil 17 between the pads 13a and 13b. Any existing method can be applied to this insulating layer forming method, and the type of insulating material is not limited. Since the formed area is small, screen printing is easy to apply.

  Third step (jumper forming step): A conductive layer to be the jumper 14 of the antenna circuit 1 is formed on the upper surfaces of the pads 13 a and 13 b and the insulating resist 18. For the formation of the conductive layer, any forming method such as a printing process using screen printing using a metal paste or a metal foil can be applied, and the type of the conductive material is not limited. The above first to third steps are steps for forming the antenna circuit 1.

  Fourth step (IC chip mounting step): A predetermined IC chip 21 is formed by attaching a bonding material to a predetermined position of the electrode part of the IC chip mounting connector 15 of the antenna circuit 1 using a flip chip mounting machine. Implement. An anisotropic conductive paste can be used as the bonding material. Thereby, the IC inlet 2 is produced.

  Fifth step (IC tag processing step): When the formation and mounting of the electrical circuit elements is completed, the surface of the IC inlet 2 is covered with an adhesive or resin, for example, a card shape, a label shape, It is made into an arbitrary shape such as a seal shape.

(Example)
An example in which the IC inlet 2 of the above embodiment is manufactured and the resonance frequency thereof is measured will be described. FIGS. 6-1 to 6-5 are diagrams for explaining an example of the IC inlet 2, and are planes for explaining a configuration example of the IC inlet 2 of the comparative example and the examples 1 to 4, respectively. FIG.

In the comparative example, a resist pattern was formed by screen printing on Cu / PET (Nikaflex manufactured by Nikkan Kogyo Co., Ltd.), in which a 35 mm copper foil was bonded to a 50 μm polyethylene terephthalate film (PET) as the circuit substrate 11 via an adhesive. By printing and etching, as shown in FIG. 6A, the planar coil 12 is spirally drawn on the circuit substrate 11 with a copper wiring having an outermost diameter of 50 mm, a line width of 400 μm, and a line spacing of 300 μm. Thus, the antenna circuit 1 having a double-sided pattern with an area of 8 mm ² was formed as the external capacitor 16. The jumper 14 shown by a wavy line was formed on the surface opposite to the surface on which the planar coil 12 was formed using a silver paste (DW250L-1 manufactured by Toyobo Co., Ltd.) with a through hole. The adjustment coil 17 is not formed. For this antenna circuit 1, a flip chip mounting machine (manufactured by Kyushu Matsushita, FB30T-M) is used, an anisotropic conductive paste (manufactured by Kyocera Chemical, TAP0402E) is used as a bonding material, and an IC chip mifare for RFID manufactured by NXP is used. (Type name MF1IC S50) was mounted by thermocompression bonding.

  As shown in FIGS. 6-2 to 6-5, in Examples 1 to 4, the adjustment coil 17 from the innermost end of the planar coil 12 is added to the IC inlet 2 according to the comparative example shown in FIG. 6A. A half of the first turn (about 139 mm), a whole of the first turn (about 278 mm), a half of the second turn (about 137 mm), and a whole of the second turn (about 274 mm) were formed.

  The resonance frequency f of the IC inlet 2 formed as described above, the coil inductance L (μH), the capacitance C “pF” of the external capacitor 16 and the IC chip 21, and the stray capacitance [pF] were measured. pF] is a value obtained by subtracting the capacitance C “pF] of the external capacitor 16 and the IC chip 21 in the IC inlet 2 and includes the capacitance due to the adjustment coil 17. This result is shown in Table 1.

  In the comparative example and Examples 1 to 4, the coil inductance L (μH) = 5.41 μH of the planar coil 12 and the capacitance C “pF” = 21.6 pF of the external capacitor 16 and the IC chip 21 are the same.

  The comparative example is the IC inlet 2 without the adjustment coil 17, the stray capacitance [pF] = 3.3 pF, and the resonance frequency f [MHz] = 13.70 MHz.

  The first embodiment is an IC inlet 2 to which the first turn half (about 139 mm) of the adjustment coil 17 is added, the stray capacitance [pF] = 4.1 pF, and the resonance frequency f [MHz] = 13.50 MHz. It became.

  Example 2 is an IC inlet 2 in which the entire first turn (about 278 mm) of the adjustment coil 17 is added, the stray capacitance [pF] = 4.9 pF, and the resonance frequency f [MHz] = 13.30 MHz. It became.

  The third embodiment is an IC inlet 2 in which the second turn (about 137 mm) of the adjustment coil 17 is further added to the second embodiment, the stray capacitance [pF] = 5.3 pF, and the resonance frequency f [ MHz] = 13.18 MHz.

  Example 4 is the IC inlet 2 in which the entire second turn (about 274 mm) of the adjustment coil 17 is further added to Example 2, the stray capacitance [pF] = 5.7 pF, and the resonance frequency f [ MHz] = 13.09 MHz.

  From the above, it was confirmed that the resonance frequency f can actually be adjusted in the direction of decreasing by increasing the length of the adjustment coil 17. In this way, the length of the adjustment coil 17 that obtains a desired resonance frequency is searched, and the adjustment coil 17 is formed to that length. It should be noted that the adjustment coil 17 formed longer may be cut or removed to adjust the resonance frequency in a larger direction to obtain a desired resonance frequency.

  Further, when adjusting the length of the adjustment coil 17, the resonance frequency may be detected for all the IC inlets 2 to be manufactured, and the length adjustment (characteristic adjustment) of the adjustment coil 17 may be performed. Alternatively, processing may be performed for each product lot as follows. For example, a predetermined number (for example, three) of IC inlets 2 are extracted from a product lot (for example, 100) of IC inlets 2 that can be regarded as having substantially the same characteristics as manufactured by the same machine at the same time, and these are extracted. The length of the adjustment coil 17 may be determined from the predetermined number of IC inlets 2, and the adjustment coil having the determined length may be formed for all the IC inlets 2 of the product lot.

(Modification 1)
In the example illustrated in FIG. 1A, the adjustment coil 17 is formed inside the planar coil 12. However, the adjustment coil 17 may be formed at another position, or a plurality of adjustment coils 17 may be formed. 7 and 8 are diagrams showing modifications of the arrangement position of the adjustment coil 17 of the antenna circuit 1. 7 and 8, parts having the same functions as those in FIG. 1-1 are denoted by the same reference numerals. For example, as shown in FIG. 7, the adjustment coil 17 may be formed outside the planar coil 12. Thereby, even when there is no space for arranging the adjustment coil 17 on the inner side, the adjustment coil 17 can be formed.

  Further, as shown in FIG. 8, the adjustment coil 17 may be formed between the wirings of the planar coil 12. Thereby, the adjustment coil 17 can be formed even when there is no space for the adjustment coil 17 inside and outside.

  The adjustment coil 17 may be arranged at least one of the inside and outside of the planar coil 12 and between the coils in consideration of the adjustment capacity and space, and may be arranged in combination. Good.

(Modification 2)
In the example illustrated in FIG. 1A, the planar coil 12 and the adjustment coil 17 have a circular shape, but may have other shapes depending on the usage mode. Other shapes may be, for example, a rectangle, a triangle, a quadrangle, a hexagon, and the like. FIG. 9 is a diagram illustrating a modification of the shape of the planar coil 12 and the adjustment coil 17 of the antenna circuit 1. 7 and 8, parts having the same functions as those in FIG. 1-1 are denoted by the same reference numerals. In the example shown in FIG. 9, the planar coil 12 and the adjustment coil 17 are rectangular.

(Effect of embodiment)
According to the above embodiment, the conductive material is formed in a loop shape with its both ends open, and a planar coil that forms a closed circuit when an IC chip is connected to both ends, outside the closed circuit, and By connecting the one end side to the planar coil, providing an adjustment coil for forming the stray capacitance along the planar coil, and adjusting the stray capacitance by adjusting the length of the adjustment coil, Since the resonance frequency is adjusted, the resonance frequency can be adjusted with low cost, simple and high accuracy.

  Further, according to the above embodiment, since the adjustment coil is formed on at least one of the inside and outside of the planar coil and between the wirings, the adjustment coil is considered in consideration of the adjustment capacity and the space. Layout becomes possible.

  As described above, the antenna circuit, the IC inlet, the IC tag, and the capacity adjustment method for the antenna circuit according to the present invention are useful for manufacturing an antenna, and particularly for non-contact type IC adhesive labels and IC cards. Is suitable.

DESCRIPTION OF SYMBOLS 1 Antenna circuit 2 IC inlet 3 IC adhesive label 4 IC card 11 Circuit base material 12 Planar coil (antenna part)
13a, 13b Pad 14 Jumper 15 IC chip mounting body 16 External capacitor 17 Adjustment coil (capacitance adjustment wiring)
18 Insulation resist 21 IC chip (electronic parts)
31, 33 Adhesive layer 32 Release material 41 Resin layer 42, 43 Surface substrate

Claims (5)

An antenna portion that is formed of an antenna wiring formed by opening a conductive material in a loop shape at both ends thereof, and forming a closed circuit when electronic components are connected to both ends of the antenna wiring; and
Capacitance adjustment wiring provided outside the closed circuit and having one end connected to the antenna wiring and formed along the antenna wiring;
An antenna circuit comprising:   The antenna circuit according to claim 1, wherein the capacitance adjusting wiring is formed on at least one of an inner side, an outer side, and a wiring between the antenna wirings. An antenna circuit according to claim 1;
Electronic components connected to both ends of the antenna wiring;
An IC inlet characterized by comprising:   An IC tag comprising the IC inlet according to claim 3. A capacity adjustment method for an antenna circuit,
The antenna circuit is
An antenna portion that is formed of an antenna wiring formed by opening a conductive material in a loop shape at both ends thereof, and forming a closed circuit when electronic components are connected to both ends of the antenna wiring; and
Capacitance adjustment wiring provided outside the closed circuit and having one end connected to the antenna wiring and formed along the antenna wiring;
With
A method of adjusting a capacity of an antenna circuit, wherein the capacity is adjusted by changing a length of the capacity adjusting wiring.

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