JP2004357203A - Antenna sheet, ic card, and forming method of capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an IC card wherein each of capacitors formed on the surface and the back of a card substrate holds predetermined capacitance. <P>SOLUTION: A surface side capacitor pattern formed on one surface of an insulating substrate is formed in a region smaller than a back side capacitor pattern formed on the other surface of the insulating substrate. A misregistration region of the same profile as a linking part is attached and formed on a side which is reverse to the linking part for linking the surface side capacitor pattern of the small region. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an antenna sheet having a capacitor, an IC card, and a method for forming a capacitor.
[0002]
[Prior art]
With the development of card technology in recent years, there is an IC card used for a wide range of applications as an information recording medium used for various systems. This IC card has a contact-type IC card in which information writing processing and reading processing are performed by being brought into contact with a dedicated device, and information writing processing and reading processing which are performed only by approaching the dedicated device. There is a non-contact type IC card in which the operation is performed. These IC cards have higher security than magnetic cards and have a large amount of information that can be written on the cards themselves, so that only one card can be used in a multifaceted manner, so that the popularity of these IC cards in the industry is ever increasing. I am following.
[0003]
Among them, in particular, a non-contact type IC card does not need to insert the IC card itself into a dedicated device when performing information writing processing or reading processing, and the handling of the card itself may be convenient, It is rapidly spreading in industry.
[0004]
Further, in recent years, IC cards in which the above-mentioned contact-type IC card and non-contact-type IC card are combined are becoming widespread, and an IC chip that performs information writing processing and reading processing in a contact state has been developed. A hybrid IC card equipped with an IC chip for performing information writing processing and reading processing in a non-contact state, and information writing processing in any of a contact state and a non-contact state And a combination type IC card on which one IC chip capable of performing read processing is mounted.
[0005]
In such an IC card, the tuning constant of a circuit composed of an antenna coil and a resonance capacitor must be accurately determined in order to obtain accurate communication characteristics, and the capacitance of the resonance capacitor is adjusted. Then, it is necessary to perform tuning correction of the circuit, and conventionally, an adjustment capacitor is provided to adjust the resonance frequency (for example, see Patent Document 1).
[0006]
[Patent Document 1]
JP 2001-10264 A
[Problems to be solved by the invention]
However, as shown in FIG. 7, since the adjusting capacitor forms a capacitor region when the front-side capacitor pattern and the back-side capacitor pattern are formed with the card substrate sandwiched therebetween, as shown in FIG. The capacitor region obtained by the capacitor pattern formed on the front and back surfaces of the card board is not formed at a predetermined position, and is shifted in a horizontal direction with respect to a connection portion for finally connecting the capacitor region to the antenna coil. If formed, the capacitor capacity corresponding to the shifted connecting portion area will decrease or increase, and it may not be possible to form a capacitor area holding a predetermined capacitor capacity on the card board. is there. For example, as shown in (a), when the misalignment direction (horizontal direction with respect to the connecting portion) is shifted toward the connecting portion, the capacitor capacity corresponding to the shifted connecting portion region decreases. I will. Further, as shown in (b), when the misalignment direction (shown in the horizontal direction with respect to the connecting portion) is shifted to the opposite side to the connecting portion, the capacitance of the capacitor corresponding to the shifted connecting portion region increases. Resulting in.
[0008]
The present invention has been made in view of the above circumstances, and an antenna that retains a predetermined capacitor capacitance even if a displacement or the like occurs and a capacitor pattern formed on the front and back surfaces of a card substrate is not formed at a predetermined position. It is an object to provide a method for forming a sheet, an IC card, and a capacitor.
[0009]
[Means for Solving the Problems]
To achieve this object, the present invention has the following features.
The invention according to claim 1 is an antenna sheet having a capacitor in which a metal piece is formed on the front and back surfaces of an insulating base with an insulating base therebetween, and an antenna coil formed on one side of the insulating base. The metal piece formed on one surface of the insulating base is a metal piece in an area smaller than the metal piece formed on the other surface of the insulating base, and the metal piece in the small area is the metal piece. The connecting portion that finally connects the piece to the antenna coil is formed by attaching a misalignment area of the same shape to the metal piece on the side opposite to the side attached to the metal piece. It is characterized by.
[0010]
According to a second aspect of the present invention, there is provided a capacitor having metal pieces formed on the front and back surfaces of the insulating base material with the insulating base material interposed therebetween, an antenna coil formed on one surface of the insulating base material, and an antenna coil. An IC card comprising: a metal piece formed on one surface of the insulating base material, the metal piece being a smaller area than the metal piece formed on the other surface of the insulating base material. The metal piece in the small area has a misalignment area of the same shape as the connection part on the side opposite to the side where the connection part that finally connects the metal piece to the antenna coil is attached to the metal piece. It is characterized by being formed so as to be attached to a piece.
[0011]
The invention according to claim 3 is a method for forming a capacitor, in which a metal piece to be a capacitor is formed on the front and back surfaces of the insulating base material, wherein the metal piece formed on one surface of the insulating base material is The metal piece formed in an area smaller than the metal piece formed on the other surface, and the metal piece formed in the small area has a connection portion that finally connects the metal piece to the antenna coil. A misalignment region having the same shape as the connection portion is formed on the metal piece on the side opposite to the side on which the connection is provided.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0013]
First, the configuration of a non-contact IC card will be described with reference to FIG.
As shown in FIG. 1, a non-contact IC card according to the present invention is mounted on an insulating card substrate 1 around an antenna coil 2 having a inductance L formed in a spiral shape and a peripheral portion thereof. It comprises a capacitor 3 forming a combined capacitance C, and an IC chip 4 on which a plurality of circuits such as a control device, a storage circuit, and an input / output circuit are mounted. The voltage induced on the card substrate 1 is detected, and the reception is performed.
[0014]
In the non-contact IC card using the short-wave band, in order to obtain sufficient communication characteristics, the constant of a tuning circuit including the antenna coil 2 and the capacitor 3 must be accurately determined. The formation of the capacitor 3 causes a large variation in the capacitance value during the formation process.
[0015]
In order to adjust such a variation in the capacitance value, the capacitor 3 forming the combined capacitance C is changed, and a different resonance frequency f is set for each non-contact IC card.
[0016]
The resonance frequency of the LC resonance circuit is calculated by the following equation (1).
[0017]
f = 1 / 2π√ (LC) Equation (1)
[0018]
As shown in the equation (1), the resonance frequency f is inversely proportional to the square root of the product of the combined capacitance C of the capacitor and the inductance L of the coil.
[0019]
Therefore, the resonance frequency f is set by short-circuiting the capacitor and reducing the capacitance of the combined capacitance C.
[0020]
As shown in FIG. 2, the capacitance C of the capacitor is such that the front-side capacitor pattern formed on the front surface of the card substrate and the back-side capacitor pattern formed on the back surface of the card substrate are symmetrically positioned via the card substrate. And the thickness d (distance between the plates) of the card substrate, and the capacitance C of the capacitor is expressed by the following equation (2). It is calculated. Here, α indicates a predetermined constant (dielectric constant).
[0021]
C = α × S / d Equation (2)
[0022]
According to the present invention, when a metal piece serving as a capacitor portion for setting the resonance frequency f is formed on the front and back surfaces of the card substrate, a predetermined capacitor capacitance C is maintained even if the formation position of the metal piece is shifted. Therefore, as shown in FIG. 3, on the side opposite to the side where the connecting portion for connecting the metal pieces serving as the capacitor C is provided, a position for correcting the capacitor capacitance when a positional shift occurs. A shift capacitor area is provided to form a front-side capacitor pattern on the card substrate.
[0023]
As a result, as shown in FIG. 4, when the formation position of the metal piece is shifted toward the connecting portion by a predetermined distance Δt, the capacitor obtained by the area ΔS of the width r × Δt of the connecting portion connecting the metal pieces. Even if the capacitance ΔC decreases, it is possible to correct the capacitance with the capacitor capacitance ΔC obtained in the displacement region ΔS, and to maintain a predetermined capacitance.
[0024]
Further, as shown in FIG. 5, when the formation position of the metal piece is shifted to the position shift area side by a predetermined distance Δt1, the capacitor obtained by the area ΔS1 of the width r × Δt1 of the connecting portion connecting the metal pieces. Even if the capacitance ΔC1 increases, it is possible to correct the capacitance with the capacitor capacitance ΔC1 obtained in the displacement area ΔS1, and to maintain a predetermined capacitance.
[0025]
Next, the pattern formation of the capacitor formed on the front and back surfaces of the card substrate will be described.
The capacitor pattern formed on the card substrate is preferably formed using a technique such as etching. The etching can accurately form a dense capacitor pattern, and can also lower the surface resistivity. Hereinafter, a method of forming a capacitor pattern by etching will be described.
[0026]
(Method of forming first capacitor pattern)
First, a method for forming the first capacitor pattern will be described.
The first method for forming a capacitor pattern is to form a conductive metal foil such as copper or aluminum on one surface of an insulating card substrate and form a front-side capacitor pattern provided with a misalignment region as shown in FIG. It is formed by etching. On the other side of the card substrate, a backside capacitor pattern as shown in FIG. 3 is formed by etching. Then, in order to connect the capacitor pattern formed on the front and back surfaces, a through hole is formed at a desired position, penetrating the front and back surfaces, and a conductive paste such as silver is inserted into the provided through hole, thereby forming the front and back surfaces. This is a forming method for electrically connecting the capacitor pattern. It should be noted that when forming capacitor patterns on both sides of the card substrate by etching, a method of “caulking” can be applied as a method of providing through holes.
[0027]
As described above, in the first method for forming a capacitor pattern, the area of the capacitor pattern formed on one side of the card substrate is smaller than the area of the capacitor pattern formed on the other side by using an etching technique, and By adding a misalignment area to the capacitor pattern formed in a small area, the capacitor capacitance of the connected part, which changes when the formation position of the capacitor pattern formed on the card board is shifted by a predetermined distance, can be misaligned. The adjustment can be performed by the capacitor capacity obtained in the region, and a predetermined capacitor capacity can be maintained.
[0028]
(Method of forming second capacitor pattern)
Next, a method for forming the second capacitor pattern will be described.
A second method for forming a capacitor pattern is to etch a conductive metal foil such as copper or aluminum on one side of a card substrate to form a front-side capacitor having a misaligned region as shown in FIG. Form a pattern. On the other surface of the card substrate, a backside capacitor pattern as shown in FIG. 3 is formed by using a conductive paste by screen printing or the like. Then, a method of forming a through hole penetrating the front and back at a desired position and inserting a conductive paste such as silver into the provided through hole to electrically connect the capacitor pattern on the front and back is formed. It is. Note that it is also possible to form the backside capacitor pattern using an etching technique and form the frontside capacitor pattern provided with the misalignment region using a printing technique.
[0029]
As described above, in the second capacitor pattern forming method, the area of the capacitor pattern formed on one side of the card substrate is made smaller than the area of the capacitor pattern formed on the other side by using the etching technique and the printing technique. In addition, by forming a capacitor pattern formed in a small area with a misalignment area attached thereto, the capacitance of the coupling portion, which changes when the formation position of the capacitor pattern formed on the card board is shifted by a predetermined distance, is reduced. In addition, the adjustment can be performed by the capacitor capacity obtained in the displacement region, and the predetermined capacitor capacity can be maintained.
[0030]
When the first and second capacitor patterns are formed, the shape of the front-side capacitor pattern formed on one surface of the insulating base material with the misalignment region is provided if the misalignment region is additionally provided. The present invention is not particularly limited, and for example, a capacitor pattern as shown in FIG. 6 can be used.
[0031]
The above-described embodiment is a preferred embodiment of the present invention, and various modifications can be made without departing from the spirit of the present invention.
For example, the capacitor pattern of the present invention can be applied to a card substrate of a type in which a capacitor pattern is formed on both sides irrespective of a contact type or a non-contact type.
Also, the capacitor pattern can be formed by using a known forming method.
[0032]
【The invention's effect】
As is clear from the above description, the present invention has the following effects.
According to the method for forming an antenna sheet, an IC card, and a capacitor according to the present invention, the metal piece formed on one surface of the insulating base material has an area smaller than the metal piece formed on the other surface of the insulating base material. A misalignment region having the same shape as the connecting portion is formed on the side opposite to the side on which the connecting portion for finally connecting the small portion of the metal piece to the antenna coil is formed. , It is possible to maintain a predetermined capacitor capacity.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an IC card on which a capacitor pattern according to the present invention is formed.
FIGS. 2A and 2B are explanatory diagrams for calculating a capacitance C of a capacitor. FIG. 2A is a cross-sectional view of a capacitor pattern formed on the front and back surfaces of a card substrate having a thickness d, and FIG. FIG. 3 is a diagram showing a capacitor region S formed by a capacitor pattern and a back-side capacitor pattern.
FIG. 3 is a view showing a capacitor pattern formed by adding a misalignment region according to the present invention.
FIG. 4 is a diagram illustrating a capacitor pattern when a formation position of a metal piece is shifted toward a connection portion by a predetermined distance Δt.
FIG. 5 is a view showing a capacitor pattern when a formation position of a metal piece is shifted toward a position shift area by a predetermined distance Δt1.
FIG. 6 is a view showing a modified example of a capacitor pattern formed by adding a misalignment region according to the present invention.
FIG. 7 is a diagram showing a capacitor capacity obtained from a conventional capacitor pattern.
8A and 8B are diagrams illustrating a conventional capacitor capacity when the formation position of the capacitor pattern is shifted, and FIG. 8A is a diagram illustrating the capacitor capacity when the position shift direction is shifted to the connecting portion side; (b) is a diagram showing the capacitance of the capacitor when the direction of the displacement is shifted to the side opposite to the connecting portion.
[Explanation of symbols]
1 Card board 2 Antenna coil 3 Capacitor 4 IC chip

Claims (3)

A capacitor having a metal piece formed on the front and back surfaces of the insulating base material with an insulating base material interposed therebetween, and an antenna coil having an antenna coil formed on one surface of the insulating base material,
The metal piece formed on one surface of the insulating base is a metal piece in a region smaller than the metal piece formed on the other surface of the insulating base,
The metal piece in the small area has a misalignment of the same shape as the connection part on the side where the connection part for finally connecting the metal piece to the antenna coil is in the opposite direction to the side attached to the metal piece. An antenna sheet formed by attaching a region to the metal piece. A capacitor in which a metal piece is formed on the front and back surfaces of the insulating base with the insulating base interposed therebetween, an antenna coil formed on one side of the insulating base, and an IC chip connected to the antenna coil; An IC card having
The metal piece formed on one surface of the insulating base is a metal piece in a region smaller than the metal piece formed on the other surface of the insulating base,
The metal piece in the small area has a misalignment of the same shape as the connection part on the side where the connection part for finally connecting the metal piece to the antenna coil is in the opposite direction to the side attached to the metal piece. An IC card comprising an area attached to the metal piece. A method for forming a capacitor that forms a metal piece to be a capacitor on the front and back surfaces of an insulating base material,
The metal piece formed on one surface of the insulating base material is formed of a metal piece in an area smaller than the metal piece formed on the other surface of the insulating base material, and is formed in the small area. The metal piece has a misalignment region of the same shape as the connection part on the side where the connection part for finally connecting the metal piece to the antenna coil is in the opposite direction to the side attached to the metal piece. A method for forming a capacitor, wherein the capacitor is formed by attaching to a piece.

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