JPWO2013191178A1 - Shield material for loop antenna, shield unit, and shield tag - Google Patents

Abstract

A shield tag having a thin shield sheet that can be suitably used in an RFID system and an NFC system is provided. An IC tag 210 on which an IC chip is mounted, a loop antenna 220 connected to the IC tag 210, a tag base 230 on which the IC tag 210 and the loop antenna 220 are mounted, and 13.56 MHz A sheet base material 120 having a plurality of strip-shaped shield materials 101a to 101c having a magnetic permeability of 200 or more and an electromagnetic wave thickness of 60 μm or less with respect to electromagnetic waves, and affixed to the tag base material 230. [Selection] Figure 1

Description

  The present invention relates to a shield material for a loop antenna, a shield unit, and a shield tag, and in particular, a shield material for a loop antenna that can be suitably used for an RFID (Radio Frequency IDentification) system and an NFC (Near Field Communication) system, and a shield It relates to a unit and a shield tag.

  2. Description of the Related Art Conventionally, there is a tag magnetic shield sheet that allows a magnetic field to be concentrated and passed without loss of magnetic field energy even when a metal is present in the vicinity (Patent Document 1). Japanese Patent Application Laid-Open No. H10-228667 discloses a shield layer made of a flat soft magnetic metal material having a large real part of the complex relative permeability μ. According to Patent Document 1, even when metal is present in the vicinity, if this shield layer is provided in the magnetic field, the magnetic lines of force pass through the shield layer in a concentrated manner. It can be said that the magnetic field in this area can be prevented from leaking to the other area. Patent Document 1 discloses that for an electromagnetic wave of 13.56 MHz, the real part μ ′ of the complex relative permeability μ is 30 or more. According to the above, it is understood that the value does not reach 100.

JP 2006-005365 A

  However, in the case of the shield sheet disclosed in Patent Document 1, when it is attempted to obtain sufficient shield characteristics, the thickness of the entire shield sheet usually exceeds 160 μm. This is because, in general, when a shield layer of the same soft magnetic metal material is used, the communication distance between the reader / writer can be increased as the thickness thereof increases.

  On the other hand, in recent years, the progress of thinning of mobile devices such as mobile phones and smartphones has been remarkable, and in order to realize this, it is required to thin various parts such as mobile devices. Of course, mobile devices are typical, but there is a demand for thinning in other industries.

  Then, this invention makes it a subject to make a shield sheet thin considering the said situation.

  In order to solve the above problems, a shield material for a loop antenna according to the present invention includes, for example, a shield material having a permeability of 200 or more and a thickness of 60 μm or less with respect to electromagnetic waves of 13.56 MHz, and at least one of the shield materials And a resin film attached to the surface via an adhesive layer.

The shield unit of the present invention is
The loop antenna shielding material;
Release paper in which the shield material for the loop antenna is arranged,
An adhesive layer formed between the shield material for the loop antenna and the release paper.

Furthermore, the shield tag of the present invention is
The loop antenna shielding material;
A loop antenna connected to the tag,
The loop antenna is covered with a shield material for the loop antenna.

BEST MODE FOR CARRYING OUT THE INVENTION

  Embodiments of the present invention will be described below with reference to the drawings. In addition, in each drawing, the same code | symbol is attached | subjected to the same part. In addition, it should be noted that the scale between the drawings and the number of members shown in each drawing may be different from the actual ones for convenience of explanation.

(Embodiment 1)
FIG. 1 is a schematic explanatory view of a shield tag according to Embodiment 1 of the present invention. The shield tag of the present embodiment is a shield tag that can be suitably used for an ISO15693 standard IC tag. As shown in FIG. 1, the shield tag of this embodiment is roughly divided into a known RFID tag 200 and a shield sheet 100 which is a shield unit attached to the RFID tag 200.

  As is known, the RFID tag 200 includes an IC tag 210 on which an IC chip is mounted, a loop antenna 220 connected to the IC tag 210, and a tag base 230 on which the IC tag 210 and the loop antenna 220 are placed. With. Note that the IC tag 210 is not necessarily provided in the RFID tag 200 itself, and may be provided separately from the RFID tag 200 and electrically connected thereto.

  The shield sheet 100 is a sheet made of, for example, a PET film or a polyimide film having a thickness of 5 μm to 30 μm to which the strip-shaped shield materials 101a to 101c and the like, which are shield materials for the loop antenna, and the shield materials 101a to 101c are attached. The base material 120 and the release paper 130 pasted on the back surface of the sheet base material 120 with respect to the pasting surfaces of the shield materials 101a to 101c and the like via an adhesive layer are provided. The conditions for the shield material 101a and the like will be described later.

  As will be described later, it is not essential for the shield tag of the present embodiment to include the shield sheet 100 itself, and functionally, the shield tag only needs to include the shield materials 101a to 101c included in the shield sheet 100. For example, it should be noted that the sheet base 120 is not essential for constituting the shield sheet 100.

  In the present embodiment, the shield sheet 100 covers one side or both sides with a resin film such as a PET film or a polyimide film. In such a case, an adhesive layer may be provided on the entire surface of the sheet substrate 120, and the shield materials 101a to 101c and the like may be arranged thereon, and then a PET film may be attached. For example, the adhesive layer may be formed using an acrylic or silicon-based adhesive. Further, the shield materials 101a to 101c and the like may be stacked in two depending on the shape and size of the loop antenna 220 or the place where the RFID tag 200 is installed.

  When the shield sheet 100 is attached to the RFID tag 200, the release sheet 130 of the shield sheet 100 is peeled off, the tag base 230 and the sheet base 120 are aligned, and the adhesive layer of the sheet base 120 is formed. What is necessary is just to affix on the tag base material 230.

  For the shield materials 101a to 101c, etc., an alloy foil whose main material is iron can be used. As an example, so-called PC permalloy foil can be used. PC permalloy is an alloy containing nickel, molybdenum, copper, iron, etc., and has a distribution ratio of 77 wt% to 78 wt% of nickel, 5 wt% of molybdenum, 4 wt% of copper, and the remainder of iron.

  Further, the shield materials 101a to 101c and the like can be alloy foils including iron, copper, niobium, silicon, boron, cobalt-based amorphous, and the like. As an example, Finemet (registered trademark) manufactured by Hitachi Metals, Ltd. can be used.

  Since the above alloy foils are usually 30 μm or less in thickness, the thickness of the entire shield sheet 100 excluding the release paper 130 is 80 μm or less even if any of them is used. The outline is as follows. When using the ESD EMAI engineering company's PC permalloy foil tape T8027, the shield materials 101a to 101c are about 24 μm, and the general-purpose adhesive layer is about 5 μm to about 30 μm. The PET film is about 30 μm.

  Therefore, when the adhesive layer having an average thickness is used, the entire thickness of the shield sheet 100 excluding the release paper 130 is about 70 μm, and even if a thick adhesive layer is used, it may be about 85 μm. On the other hand, in the case of the conventional typical shield sheet, the corresponding thicknesses are about 150 μm and about 160 μm, respectively, so that it is possible to reduce the thickness to about ½ compared to these. Become.

  Further, even if two shield materials 101a to 101c are used in a stacked manner, the thickness of the entire shield sheet 100 excluding the release paper 130 is 110 μm or less. Also in this case, the thickness can be reduced to about 2/3 as compared with the conventional typical shield sheet.

  By the way, generally, the communication improvement effect by the shield sheet is adjusted based on the thickness and magnetic permeability of the shield material. When the shield material is made thin, the magnetic permeability of the shield material must be increased.

  The shield materials 101a to 101c and the like according to the present embodiment are made of PC permalloy, fine met, etc., and their magnetic permeability is 200 or more with respect to electromagnetic waves in frequency bands such as 13.56 MHz, 135 KHz, 100 KHz, and 90 KHz. is there. The magnetic permeability of the shield material increases when a high magnetic permeability material such as niobium is added by several atomic%.

  Here, what is important for the shield sheet 100 of the present embodiment to obtain a sufficient shielding effect is the permeability, shape, size, etc. of the shield materials 101a to 101c and the arrangement of the shield materials 101a to 101c etc. with respect to the sheet substrate 120. It is in.

  First, for the shield materials 101a to 101c according to the present embodiment, an alloy foil having a thickness of 30 μm or less should be selected. Otherwise, in some cases, since the shield materials 101a to 101c and the like use two PC permalloy foil tapes as described above, when considering the thickness of the sheet substrate 120 and the PET film, This is because the entire shield sheet 100 cannot be made so thin as compared to the case. In such a case, it has been found that the magnetic permeability of the shield materials 101a to 101c and the like should be approximately 200 or more.

  In addition, when an alloy foil as described above is selected, if a shape like a conventional shield material is adopted, it flows to the loop antenna 220 in order to communicate with a reader / writer (not shown) according to Lenz's law. A current that flows in a direction opposite to the direction of the current is generated. In this case, both currents cancel each other, so that the signal from the RFID tag 200 cannot be received by the reader / writer.

  In this case, in other words, the shield material acts in the same manner as the metal existing in the vicinity of the RFID tag 200, and thus the energy of the magnetic field is lost. This reduces the communication effect.

  Therefore, as shown in FIG. 1, strip-shaped shield materials 101 a to 101 c are employed, and the shield materials 101 a to 101 c are stuck between the shield materials 101 a to 101 c even if the current cancels out. In such a position, the cancellation is avoided.

  The shield materials 101a to 101c and the like are arranged so as to cover the antenna coil constituting the loop antenna 220 and to be orthogonal to the extending direction. The distance between the shield material 101a and the shield material 101b may be 3 mm to 15 mm, for example, and is 10 mm in this embodiment, for example. The distance between the shield material 101b and the shield material 101c may be set to the same condition as this.

  Here, the conventional typical shield sheet is usually provided with a shield material having the same shape as that of the shield sheet body, but naturally, the area of the shield material is also relatively increased. Since the shield material is generally expensive, the cost of the shield sheet 100 is relatively high. On the other hand, in the case of this embodiment, since the area of a shield material may be small, the cost of the shield sheet 100 can be suppressed.

  Further, the length of the shield material 101a or the like may be set to reach, for example, about 3 mm to 5 mm inside the innermost circumference of the antenna coil constituting the loop antenna 220. Furthermore, the width of the shield material 101a and the like may be, for example, about 5 mm to 10 mm. The number of shield materials 101a and the like may be determined according to the size of the RFID tag 200. But in order to process the shield sheet 100 easily, you may stick the shield materials 101a-101c etc. over the both ends of the sheet | seat base material 120. FIG.

  In other words, FIG. 1 shows three shield materials that respectively oppose the shield materials 101a to 101c, but instead of these three opposing shield materials, the shield materials 101a to 101c are replaced by the sheet base material 120. It is good also as an integral thing extended from end to end. The shield material 101 may be provided at a position corresponding to the IC tag 210 and a position corresponding to a connection line connecting the IC tag 210 and the loop antenna 220. This is because the cancellation described above can be avoided also in these places.

  Here, as described above, the shield sheet 100 can be covered with the resin film, and the shield tag of the present embodiment only needs to include the shield material 101 functionally. From this point of view, the relationship between the shield material 101 and the resin film will be added.

  First, the shield material 101 can be considered to cover one side with a resin film or both sides through an adhesive layer. In the former case, the resin film contributes to maintaining the shape of the shield sheet 100 and preventing the shield material 101 from being oxidized. On the other hand, in the latter case, one of the resin films and the adhesive layer attached thereto also function as a spacer between the shield material 101 and the loop antenna 220.

  Next, the relationship between the resin film and the shield material 101 will be described. First, the following four modes are conceivable as modes for covering the shield material 101 with a resin film.

(First aspect)
It is conceivable to cover only the first surface of the shield material 101 with a resin film through the first adhesive layer. In this case, the shield material 101 will stick the 2nd surface which is not covered with the resin film to the tag base material 230 through another adhesion layer. The first surface of the shield material 101 is prevented from oxidation by being blocked from the outside air by the resin film, and the second surface is prevented from being oxidized by being blocked from the outside air by the other adhesive layer.

  In addition, about the resin film, it does not necessarily need to be a single | mono layer and may be comprised with a multilayer. In such a case, since only the other adhesive layer functions as a spacer, it is also a method to make the thickness sufficient to function as a spacer. Specifically, although the adhesive layer depends on the frequency band related to the loop antenna 220, in the case of an electromagnetic wave of 13.56 MHz, it is preferable to secure about 15 μm.

(Second aspect)
As a 2nd aspect, it is possible to cover also the 2nd surface in the shielding material 101 of a 1st aspect with a resin film through a 2nd adhesion layer. In the case of the first aspect, the resin film contributes to maintaining the shape of the shield material 101 before being attached to the tag base material 230, and contributes to oxidation prevention after being attached to the tag base material 230. However, when it takes a long time from when the shield material 101 is manufactured to be attached to the tag base material 230, it is necessary to prevent oxidation from the second surface of the shield material 101.

  For this reason, it is conceivable to cover both the first and second surfaces of the shield material 101 with a resin film. In such a case, the second adhesive layer and the resin film on the second surface side function as spacers. Therefore, in this case, the thickness of the second adhesive layer may be relatively thinner than that of the first embodiment due to the presence of the resin film incidental thereto. 2 The total thickness of the adhesive layer and the resin film may be about 15 μm.

(Third aspect)
As a 3rd aspect, it is possible to cover the 2nd surface in the shielding material 101 of a 1st aspect with a release paper through a 2nd adhesion layer. In the case of the third aspect, as in the second aspect, the second adhesive layer contributes to the prevention of oxidation, and if the release paper is peeled off, the shield material 101 is attached to the tag base through the second adhesive layer. It can be easily attached to the material 230. In this case, since the second adhesive layer functions as a spacer, the thickness of the second adhesive layer should be approximately the same as that of the first aspect.

(Fourth aspect)
As a 4th aspect, all the elements of the 1st-3rd aspect shall be included. Specifically, it is conceivable that any of the resin films of the shield material 101 of the second aspect is covered with a release paper via a third adhesive layer. If the release paper is peeled off, the shield material 101 can be easily attached to the tag base material 230 through the third adhesive layer.

  In such a case, the second and third adhesive layers and the resin film therebetween function as spacers. Therefore, in this case, the thickness of the second adhesive layer may be relatively thin as compared with the case of the first aspect due to the presence of the resin film incidental thereto. Specifically, in the above example, the total thickness of the second and third adhesive layers and the resin film therebetween may be about 15 μm.

  By the way, the shield sheet of this embodiment is required to have a total thickness of 80 μm or less. What is necessary is just to adjust the total thickness of the shield sheet of this embodiment with the thickness of each adhesion layer and each resin film. However, in order to obtain the sufficient adhesive effect, the adhesive layer generally has a thickness of at least about 10 μm. The thickness of the resin film may be determined based on the total thickness of the shield sheet.

  Then, for example, in the case of the first aspect, simply showing an example of the thickness of each member, the shielding material 101 having a thickness of about 18 μm, the first adhesive layer having a thickness of about 10 μm, and about 5 μm. In such a case, the other adhesive layer on the second surface side may be about 15 μm in the case of the above example. In this case, the total thickness of the shield sheet is [18 μm + 10 μm + 5 μm + 15 μ = 48 μm].

  FIG. 2 is a schematic diagram of a shield tape 300 that is a shield unit including the shield members 101a to 101c shown in FIG. FIG. 2 shows the shield materials 101a to 101c described above and the release paper 140 to which the shield material 101a and the like are attached. An adhesive layer (not shown) formed between the shield materials 101a to 101c and the release paper 140 is provided.

  The shield materials 101a to 101c may be covered with a resin film such as a PET film or a polyimide film. In such a case, an adhesive layer may be provided on the entire surface of the release paper 140, and the shield materials 101a to 101c may be arranged thereon, and then a PET film may be attached.

  The length of the shield tape 300 may be 1 m to 10 m, for example. The shield materials 101a to 101c are pasted on the release paper 140 with an interval of, for example, 5 mm to 15 mm. Therefore, when manufacturing the shield sheet 100, for example, the shield tape 300 is cut to a required length, and then the shield materials 101a to 101c are integrally attached to the sheet substrate 120 while peeling the release paper 140. If it does, it will become possible to arrange | position the shielding materials 101a-101c to the sheet | seat base material 120 at equal intervals.

  In addition, you may change the process order of sticking to the sheet | seat base material 120 of the shielding materials 101a-101c, and the cutting | disconnection of the shielding tape 300. FIG. Also in this case, the mutual space | interval of the shield materials 101a-101c in the sheet | seat base material 120 can be hold | maintained easily.

(Embodiment 2)
FIG. 3 is a schematic explanatory view of a shield tag according to the second embodiment of the present invention, and corresponds to FIG. In the shield tag shown in FIG. 3, shield materials 101 a to 101 d are formed at positions corresponding to the four sides of the substantially rectangular loop antenna 220 instead of the shield materials 101 a to 101 c described above.

  Here, the shield materials 101a and 101c have the same shape, and the shield materials 101b and 101d also have the same shape. The width of the shield material 101a to the shield material 101d may be equal to or greater than the width of the loop antenna 220 (the distance between the innermost antenna coil and the outermost antenna coil). In order to cover the width direction of the antenna 220, for example, the width is about 2 mm larger than the width of the loop antenna 220.

  Regarding this point, the shield tag created by attaching the shield sheet 100 to the RFID tag 200 was verified with a reader / writer compatible with the ISO 14443 standard for the NFC system. In addition, as conditions for the shield tag, the width of the loop antenna 220 is 4 mm, the width of the shield material 101a and the like is 6 mm, the center of the width of the loop antenna 220 and the center of the width of the shield material 101a and the like are matched, It was confirmed that good communication characteristics can be obtained when 101a and the like protrude from the loop antenna 220 by 1 mm on both sides.

  It has been found that the communication distance between the shield tag and the reader / writer is saturated even when the width of the shield material 101a or the like is larger. In this case, it is preferable to reduce the material cost of the entire shield tag by reducing the amount of use of the shield material 101a and the like. Conversely, it has also been found that if the width of the shield material 101a or the like is less than the width of the loop antenna, the communication characteristics deteriorate in proportion to the phenomenon of the width.

  In addition, by experiment, the loop antenna and the shielding material 101a with respect to the total area of the loop antenna (area surrounded by the outer edge defined by the innermost antenna coil and the outer edge defined by the outermost antenna coil). It was found that the total area of the overlapping portions with −101 d is preferably about 50% or more. Further, it was found that the communication distance characteristic takes a peak value near 70% and decreases when the total area ratio is increased toward 100%. The communication distance characteristic depends on the material constant of the shield material attached to the antenna, and the peak value can be predicted by the impedance characteristic of the antenna when the shield material is mounted.

  The grounds that the above total area ratio may be 50% or more are that shield tags currently on the market have a communication distance of about 10 mm to 20 mm. If the total area ratio is 50% or more, 20 mm This is because the above communication distance can be realized.

  Moreover, even if the shield tag has a total area ratio of 100%, the manufacturing cost is almost the same as that of the shield tag currently on the market. And can be manufactured at low cost.

  Even when the shielding material 101a or the like is attached in this way, the cancellation as described in the first embodiment can be avoided.

  As described above, in each embodiment of the present invention, the example in which the shield material 101a or the like is attached to the RFID tag 200 through the sheet base material 120 has been described. However, a plurality of shield materials 101a and the like covered with a resin film or the like are prepared, It is also possible to place them in place. The contents described in the embodiments of the present invention can also be applied to wireless power feeding in which power is transmitted without using a metal contact or a connector.

It is typical explanatory drawing of the shield tag of Embodiment 1 of this invention. It is a schematic diagram of the shielding tape 300 containing the shielding materials 101a-101c etc. which are shown in FIG. It is typical explanatory drawing of the shield tag of Embodiment 2 of this invention.

DESCRIPTION OF SYMBOLS 100 Shield sheet 101a-101c Shield material 120 Sheet base material 130 Release paper 140 Release paper 200 RFID tag 210 IC tag 220 Loop antenna 230 Tag base material 300 Shield tape

Claims (3)

A shielding material having a magnetic permeability of 200 or more and a thickness of 60 μm or less with respect to electromagnetic waves;
A shield material for a loop antenna, comprising: a resin film attached to at least one surface of the shield material via an adhesive layer. A shielding material having a magnetic permeability of 200 or more and a thickness of 60 μm or less with respect to electromagnetic waves;
Release paper in which the shield material is arranged;
A shield unit comprising: an adhesive layer formed between the shield material and the release paper. A shielding material having a magnetic permeability of 200 or more and a thickness of 60 μm or less with respect to electromagnetic waves;
A loop antenna connected to the IC tag,
The loop antenna is a shield tag covered with the shield material.

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