JP2010283075A - Electromagnetic wave absorbent sheet, method for manufacturing the same, electromagnetic wave absorbent sheet laminated body and member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic wave absorbent sheet and an electromagnetic wave absorbent sheet laminated body which have favorable electromagnetic wave absorption efficiency while reducing thicknesses. <P>SOLUTION: The electromagnetic wave absorbent sheet 1 includes an insulating film 2, and a group of electromagnetic wave absorbing films 3 formed on a surface of the insulating film 2. The insulating film 2 has a laterally long rectangular shape, and the electromagnetic absorbing film 3 has a transversely long rectangular shape, and is arranged to be substantially parallel to each other in the long-side direction. In the electromagnetic wave absorbing film 3, the ratio a/b of a long-side length a to a short-side length b is 1-2,000, the ratio a/c of the long-side length a to a thickness c is 5-2,000,000, and the ratio b/c of the short-side length b to a thickness c is 2.5-1,000,000. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electromagnetic wave absorbing sheet, a manufacturing method thereof, an electromagnetic wave absorbing sheet laminate, and a member provided with the electromagnetic wave absorbing sheet or the electromagnetic wave absorbing sheet laminate.

  In recent years, with the spread of OA equipment, communication equipment, etc., electromagnetic waves generated from these equipment have been regarded as a problem. That is, there are concerns about the influence of electromagnetic waves on the human body, and malfunctions of precision equipment due to electromagnetic waves are problematic.

  Therefore, various electromagnetic wave absorbing materials have been put to practical use in order to block magnetism and radio waves. Such electromagnetic wave absorbers include, for example, front filters of PDPs for OA equipment, window materials for installation of precision equipment such as hospitals and laboratories, CPUs in personal computers, flexible printed boards (liquid crystals, optical pickups), boards in digital cameras, It is used for RFID such as HF band.

  Japanese Patent Application Laid-Open No. 10-322085 discloses that an electromagnetic wave shielding sheet obtained by embedding a metal powder in the form of a layer on the surface of an insulating layer is manufactured by roll molding or extrusion molding.

  When performing roll forming, an insulating material is inserted between a pair of rolls, and metal powder is sprayed and added to the surface of the inserted insulating material. Thereby, the electromagnetic wave shielding sheet in which the metal powder is embedded in layers is manufactured.

  When performing extrusion molding, the whole surface of the massive insulating material is added with metal powder, pressed with a press or the like in the vertical direction, and thinned to form. By cutting out this molded body in a predetermined area, an electromagnetic wave shielding sheet in which the metal powder is embedded in layers is manufactured.

  When an electromagnetic wave hits the electromagnetic wave shielding sheet, the metal powder itself in the electromagnetic wave shielding sheet absorbs the electromagnetic wave.

  Japanese Patent Laid-Open No. 2005-183652 discloses that a mask-like transparent conductive film is formed on the base film by disposing a mask between the metal target and the base film and sputtering the metal target. It is disclosed that an electromagnetic shielding material is formed. This network-like transparent conductive film is electrically connected to the ground.

  When electromagnetic waves are incident on the transparent conductive film of the electromagnetic shielding material, a current is generated, and the current flows through the transparent conductive film to the ground.

Japanese Patent Laid-Open No. 10-322085 JP 2005-183652 A

  When manufacturing an electromagnetic wave shielding sheet by roll molding or extrusion molding as in Patent Document 1 (Japanese Patent Laid-Open No. 10-322085), it is difficult to precisely control the dispersion state of the metal powder in the insulating material. Therefore, it is difficult to reduce the thickness of the electromagnetic wave shielding sheet and to sufficiently improve the electromagnetic wave absorption performance.

  Moreover, the electromagnetic wave shielding material of patent document 2 (Unexamined-Japanese-Patent No. 2005-183652) can be used only when a transparent conductive film can be connected to earth | ground.

  Furthermore, since the electromagnetic shielding material of Patent Document 2 has a shape that makes it possible to connect the pattern shape of the transparent conductive film to the ground, it is possible to improve the electromagnetic wave absorption efficiency of the transparent conductive film by devising such a pattern shape. Have difficulty.

  That is, the shape of the electromagnetic wave absorber affects the electromagnetic wave absorption efficiency. For example, a larger ratio of the long side to the short side (long side / short side) of the electromagnetic wave absorbing material is basically preferable, but if it is too large, the electromagnetic wave absorption efficiency decreases. In the electromagnetic wave shielding material of Patent Document 2, since the current flowing in the transparent conductive film needs to flow to the ground, the pattern shape of the transparent conductive film needs to be a net (a shape in which a plurality of lines are connected to each other). is there. Thus, since the shape of a transparent conductive film is restrict | limited, it is difficult to improve the electromagnetic wave absorption efficiency of a transparent conductive film.

  The present invention is an electromagnetic wave absorbing sheet capable of reducing the thickness and capable of improving electromagnetic wave absorption efficiency and a method for producing the same, and an electromagnetic wave absorbing sheet laminate formed by laminating the electromagnetic wave absorbing sheet, It aims at providing the member provided with this electromagnetic wave absorption sheet or an electromagnetic wave absorption sheet laminated body.

  The electromagnetic wave absorbing sheet of the present invention (invention 1) is an electromagnetic wave absorbing sheet having an insulating film and a plurality of electromagnetic wave absorbing films formed at intervals on the surface of the insulating film, the electromagnetic wave absorbing film Has an elongated shape whose length in the longitudinal direction is larger than the length in the short direction, and the plurality of electromagnetic wave absorbing films are characterized in that their longitudinal directions are substantially parallel to each other.

  The electromagnetic wave absorbing sheet according to claim 2 is characterized in that, in claim 1, the electromagnetic wave absorbing film is rectangular or elliptical.

  The electromagnetic wave absorbing sheet according to claim 3 is the electromagnetic wave absorbing film according to claim 1 or 2, wherein the electromagnetic wave absorbing film has a ratio a / b of a length a in the longitudinal direction to a length b in the short direction of 1 to 2000. Features.

  The electromagnetic wave absorbing sheet according to claim 4 is the electromagnetic wave absorbing film according to any one of claims 1 to 3, wherein the electromagnetic wave absorbing film has a ratio b / c of the length b in the short direction to the thickness c of 2.5 to 1,000,000. It is characterized by being.

  The electromagnetic wave absorbing sheet according to claim 5 is the electromagnetic wave absorbing film according to any one of claims 1 to 4, wherein the electromagnetic wave absorbing film has a ratio a / c between the length a in the longitudinal direction and the thickness c of 5 to 2,000,000. It is characterized by.

  The electromagnetic wave absorbing sheet according to claim 6 is characterized in that 50 to 95% of the area of the insulating film is covered with the electromagnetic wave absorbing film in any one of claims 1 to 5.

  The electromagnetic wave absorbing sheet according to claim 7 is characterized in that, in any one of claims 1 to 6, the insulating film is made of a synthetic resin.

  The electromagnetic wave absorbing sheet according to claim 8 is characterized in that, in claim 7, the synthetic resin is a photo-curing resin, a thermoplastic resin or a thermosetting resin.

  The electromagnetic wave absorbing sheet according to claim 9 is characterized in that, in claim 7 or 8, the insulating film has a thickness of 1 to 200 μm.

  An electromagnetic wave absorbing sheet according to a tenth aspect is characterized in that in any one of the first to eighth aspects, the electromagnetic wave absorbing film is made of a thin film of a magnetic material.

  The electromagnetic wave absorbing sheet according to claim 11 is characterized in that, in claim 10, the electromagnetic wave absorbing film is magnetized in a certain direction.

  The electromagnetic wave absorbing sheet laminate of the present invention (invention 12) is characterized in that a plurality of the electromagnetic wave absorbing sheets described in any one of claims 1 to 11 are included.

  The electromagnetic wave absorbing sheet laminate according to claim 13 is the electromagnetic wave absorbing film laminate according to claim 12, wherein the arrangement pattern of the electromagnetic wave absorbing film in at least one electromagnetic wave absorbing sheet is different from the arrangement pattern of the electromagnetic wave absorbing film in at least one other electromagnetic wave absorbing sheet. Features.

  The electromagnetic wave absorbing sheet laminate according to claim 14 is the electromagnetic wave absorbing film arrangement pattern according to claim 13, wherein the arrangement pattern of the electromagnetic wave absorbing film in each electromagnetic wave absorbing sheet is arranged by shifting the phase of the arrangement pattern of the electromagnetic wave absorbing film in at least one other electromagnetic wave absorbing sheet. It is characterized by a pattern.

  The method for producing an electromagnetic wave absorbing sheet according to the present invention (invention 15) is a method for producing the electromagnetic wave absorbing sheet according to any one of claims 1 to 11, wherein a mask is disposed so as to overlap or face an insulating film. Then, the electromagnetic wave absorbing film is formed by sputtering.

  The member of the present invention (invention 16) is provided with the electromagnetic wave absorbing sheet according to any one of claims 1 to 11.

  The member of the present invention (invention 17) is provided with the electromagnetic wave absorbing sheet laminate according to any one of claims 12 to 14.

  In the electromagnetic wave absorbing sheet of the present invention (invention 1), a plurality of electromagnetic wave absorbing films are formed at intervals on the surface of the insulating film. For this reason, compared with the case where metal powder is embedded in the surface of an insulating layer like patent document 1, the thickness of an electromagnetic wave absorption sheet can be made small and electromagnetic wave absorption efficiency can be made favorable.

  In addition, since the electromagnetic wave absorbing film has an elongated shape whose length in the longitudinal direction is larger than the length in the lateral direction, compared to the case where the length in the longitudinal direction and the length in the lateral direction are the same, Increases electromagnetic wave absorption efficiency.

  Furthermore, the longitudinal directions of the plurality of electromagnetic wave absorbing films are substantially parallel to each other. For this reason, the electromagnetic wave absorption efficiency can be made favorable by arranging a plurality of electromagnetic wave absorption films densely.

  In this electromagnetic wave absorbing sheet, the electromagnetic wave absorbing film is preferably rectangular or elliptical. Thereby, a plurality of electromagnetic wave absorbing films can be arranged more densely.

  In this electromagnetic wave absorbing film, the ratio a / b between the length a in the longitudinal direction and the length b in the short direction is 1 to 2000, and the ratio b / in the length b in the short direction and the thickness c is b /. It is preferable that c is 2.5 to 1,000,000, and the ratio a / c between the length a in the longitudinal direction and the thickness c is 5 to 2,000,000. Within this range, the electromagnetic wave absorption efficiency is high.

  Here, the length a in the longitudinal direction means the length of a line segment (hereinafter referred to as a long line segment) that connects the two most distant points in the periphery of the electromagnetic wave absorbing film, and the length b in the short direction. Means the length of the largest width among the widths of the electromagnetic wave absorbing film in the direction perpendicular to the long line segment.

  It is preferable that 50 to 95% of the area of the insulating film is covered with the electromagnetic wave absorbing film. When it is 50% or more, the electromagnetic wave absorption efficiency is good, and when it is 95%, the electromagnetic wave absorption films are well prevented from contacting each other.

  This insulating film is preferably made of a synthetic resin such as PP, PE, or PET. Moreover, it is preferable that the thickness of this insulating film is 1-200 micrometers. When it is 1 μm or more, the handleability of the insulating film 2 is improved, and when it is 200 μm or less, the electromagnetic wave absorbing sheet is made thin.

  This electromagnetic wave absorbing film is preferably made of a thin film of a magnetic material.

  This electromagnetic wave absorbing film is preferably magnetized in a certain direction. Thereby, the electromagnetic wave absorption efficiency of the electromagnetic wave absorbing film becomes better.

  In the electromagnetic wave absorbing sheet laminate of the present invention (invention 12), the electromagnetic wave absorbing efficiency is further improved because the electromagnetic wave absorbing sheet has a plurality of layers. When the insulating film is made of a thermoplastic resin, an electromagnetic wave absorbing sheet laminate can be easily obtained without using an adhesive by stacking and heat-sealing a plurality of electromagnetic wave absorbing sheets. .

  In this electromagnetic wave absorbing sheet laminate, the arrangement pattern of the electromagnetic wave absorbing film in at least one electromagnetic wave absorbing sheet is preferably different from the arrangement pattern of the electromagnetic wave absorbing film in at least one other electromagnetic wave absorbing sheet. In this case, at least a part of the interval between the electromagnetic wave absorbing films in the one electromagnetic wave absorbing sheet is covered with the electromagnetic wave absorbing film in the at least one other electromagnetic wave absorbing sheet. Thereby, it is further prevented that electromagnetic waves leak from the interval.

  In addition, it is preferable that the arrangement pattern of the electromagnetic wave absorption film in each electromagnetic wave absorption sheet is an arrangement pattern in which the phase of the arrangement pattern of the electromagnetic wave absorption film in the other at least one electromagnetic wave absorption sheet is shifted. Thereby, the space | interval of the electromagnetic wave absorption films of a certain layer can be satisfactorily covered with the electromagnetic wave absorption film of another layer.

  As a method for producing this electromagnetic wave absorbing sheet, it is preferable that the electromagnetic wave absorbing film is formed by sputtering with an insulating film placed over or facing the mask. Thereby, an electromagnetic wave absorption sheet can be manufactured easily. Moreover, the shape of the electromagnetic wave absorbing film can be changed to a desired shape.

  The electromagnetic wave absorbing sheet and the electromagnetic wave absorbing sheet laminate can be applied to various members serving as an electromagnetic wave generation source such as a mobile phone, a PC, and an electronic device.

(A) is a top view of the electromagnetic wave absorption sheet 1, (b) is sectional drawing in alignment with the BB line of (a), (c) is dimension explanatory drawing of an electromagnetic wave absorption film | membrane. 1 is a diagram illustrating an example of a method for producing an electromagnetic wave absorbing sheet 1. It is a top view of the mask 10 of FIG. (A) is a top view before superimposing the four electromagnetic wave absorption sheets 1, (b) is sectional drawing which shows the state superimposed. It is a partial top view of 1 A of electromagnetic wave absorption sheets which concern on different embodiment. It is a top view of another electromagnetic wave absorption film 3B. It is a top view of another electromagnetic wave absorption film 3C. It is a top view of electromagnetic wave absorption film 3D. (A) is a top view of electromagnetic wave absorption sheet 1B, (b) is sectional drawing of an electromagnetic wave absorption sheet laminated body. It is a top view of electromagnetic wave absorbing sheet 1C.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 (a) is a plan view of an electromagnetic wave absorbing sheet according to the embodiment, FIG. 1 (b) is a cross-sectional view taken along line BB of FIG. 1 (a), and FIG. Drawing explaining an example of the manufacturing method of an electromagnetic wave absorption sheet, FIG. 3 is a top view of the mask of FIG.

  As shown in FIG. 1, the electromagnetic wave absorbing sheet 1 is an electromagnetic wave comprising an insulating film 2 and a plurality (36 in this embodiment) of electromagnetic wave absorbing films 3 formed on the surface of the insulating film 2 at intervals. It consists of an absorbing film group.

  As shown in FIG. 1 (a), the insulating film 2 has a rectangular shape that is long in the horizontal direction of the figure. This electromagnetic wave absorbing film group is formed by arranging a plurality of rows of electromagnetic wave absorbing films 3 arranged at intervals in the horizontal direction in a plurality of rows in the vertical direction. These electromagnetic wave absorbing films 3 have a horizontally long rectangular shape and are arranged so that their longitudinal directions are substantially parallel to each other.

  Here, “substantially parallel” means that the crossing angle between the extension lines in the longitudinal direction (in this case, the diagonal direction) of the different electromagnetic wave absorption films 3 is 5 ° or less.

  The length (diagonal length) a in the longitudinal direction of the rectangular electromagnetic wave absorbing film 3 is preferably 10 to 10,000 μm, more preferably 50 to 5000 μm, and particularly preferably 100 to 1000 μm. If it is 10,000 μm or more, eddy currents are generated and electromagnetic waves are emitted. When the thickness is 10 μm or less, it is difficult to align the pattern after the deposition film is formed.

  The length of the rectangular electromagnetic wave absorbing film 3 in the short direction (length in the direction orthogonal to the diagonal) b is preferably 5 to 5000 μm, more preferably 10 to 1000 μm, and particularly preferably 20 to 500 μm. If it is 5000 μm or more, unnecessary electromagnetic waves due to eddy currents are likely to be generated. If the thickness is 5 μm or less, it is difficult to align the pattern after vapor deposition.

  The thickness c of the rectangular electromagnetic wave absorbing film 3 is preferably 0.005 to 2 μm, more preferably 0.05 to 1 μm, and particularly preferably 0.1 to 0.5 μm. Electromagnetic wave absorption efficiency is favorable in it being 0.1 micrometers or more. When the thickness is 0.5 μm or less, the electromagnetic wave absorbing film can be thinned.

The distance d ₁ between the electromagnetic wave absorbing films 3 adjacent in the long side direction is preferably 5 to 500 μm, more preferably 10 to 250 μm, and particularly preferably 20 to 100 μm. When the thickness is 20 μm or more, when the electromagnetic wave absorbing film 3 is produced on the insulating film 2, the adjacent electromagnetic wave absorbing films 3 are favorably prevented from contacting each other. When the thickness is 100 μm or less, the electromagnetic wave absorbing film 3 can be densely arranged on the insulating film 2 and the electromagnetic wave absorption efficiency can be improved.

The distance d ₂ between the electromagnetic wave absorbing films 3 adjacent to each other in the short side direction is preferably 5 to 500 μm, particularly 10 to 250 μm, and particularly 20 to 100 μm. When the thickness is 20 μm or more, when the electromagnetic wave absorbing film 3 is produced on the insulating film 2, the adjacent electromagnetic wave absorbing films 3 are favorably prevented from contacting each other. When the thickness is 100 μm or less, the electromagnetic wave absorbing film 3 can be densely arranged on the insulating film 2 and the electromagnetic wave absorption efficiency can be improved.

  The ratio a / b between the length a in the longitudinal direction and the length b in the short direction of the electromagnetic wave absorbing film 3 is preferably 1 to 2000, particularly 1 to 200, and particularly 1 to 20. Within this range, electromagnetic wave absorption efficiency is high.

  The ratio a / c between the length a and the thickness c in the longitudinal direction of the electromagnetic wave absorbing film 3 is preferably 5 to 2000000, more preferably 100 to 500000, and particularly preferably 200 to 10000. Within this range, electromagnetic wave absorption efficiency is high.

  The ratio b / c between the length b in the short direction of the electromagnetic wave absorbing film 3 and the thickness c is preferably 2.5 to 100,000, more preferably 20 to 100,000, and particularly preferably 40 to 5,000. Within this range, electromagnetic wave absorption efficiency is high.

  The material of the electromagnetic wave absorbing film 3 is not particularly limited. For example, soft magnetic metal such as Fe-Si-Al alloy (Sendust), Ni-Fe alloy (Permalloy), soft ferrite, iron, silicon steel, Fe-Ni Examples thereof include magnetic materials such as -Mo, Fe-Co, and μ metal (Fe-Ni-Cu-Cr).

  The thickness of the insulating film 2 is preferably 1 to 200 μm, more preferably 10 to 50 μm, and particularly preferably 10 to 20 μm. When it is 10 μm or more, the handleability of the insulating film 2 is improved. When the thickness is 20 μm or less, the electromagnetic wave absorbing sheet can be made thin.

  It is preferable that 50 to 95% of the area of the insulating film 2 is covered with the electromagnetic wave absorbing film 3. When it is 50% or more, the electromagnetic wave absorption efficiency is good. When the content is 95% or less, the electromagnetic wave absorbing films 3 can be satisfactorily prevented from contacting each other.

  The material of the insulating film 2 is not particularly limited, and examples thereof include synthetic resins such as polypropylene and polyethylene.

  Next, an example of the manufacturing method of said electromagnetic wave absorption sheet 1 is demonstrated.

  The mask 10 of FIG. 3 is provided with openings 11 having the same pattern as the arrangement pattern of the electromagnetic wave absorbing film 3 in the electromagnetic wave absorbing sheet 1 of FIG.

  As shown in FIG. 2, this mask 10 is placed on the insulating film 2 so as to overlap or face each other and placed in the sputtering apparatus, and the target 20 held by the holder 21 is sputtered. Thereby, the electromagnetic wave absorbing film 3 is formed on the insulating film 2. Thus, the electromagnetic wave absorption film 3 manufactured by sputtering has a small distortion.

  Examples of the material of the target 20 include soft magnetic metals such as Fe—Si—Al alloy (Sendust) and magnetic materials such as Ni—Fe alloy (Permalloy). A plurality of targets having different compositions may be sputtered. For example, when manufacturing an electromagnetic wave absorbing film made of a Ni—Fe alloy, a Ni target and a Fe target may be sputtered simultaneously, or two types of Ni—Fe alloy targets having different compositions may be sputtered simultaneously. It may be.

  As sputtering conditions, for example, the sputtering voltage is 1.0 to 1.5 kW, the Ar gas flow rate during sputtering is 5 to 50 sccm, the sputtering time is 60 to 600 seconds, the sputtering pressure is 0.5 to 1.2 Pa, and the deposition rate is 0. It is preferable to set it as 1-0.5 nm / s.

  As a material of this mask, Ni-Co, SUS or the like is preferable.

  In the electromagnetic wave absorbing sheet 1 according to the present embodiment, a plurality of electromagnetic wave absorbing films 3 are formed on the surface of the insulating film 2 at intervals. For this reason, compared with the case where the electromagnetic wave absorber is embedded in the surface of the insulating film in a layered manner as in the prior art, the thickness of the electromagnetic wave absorbing sheet 1 can be reduced and the electromagnetic wave absorption efficiency can be improved.

  Further, the electromagnetic wave absorbing film 1 has an elongated shape in which the length a in the long side direction is larger than the length b in the short side direction, so that the length in the longitudinal direction is the same as the length in the short direction. The electromagnetic wave absorption efficiency is higher than in some cases.

  Further, the plurality of electromagnetic wave absorbing films 3 are substantially parallel to each other in the long side direction. For this reason, a plurality of electromagnetic wave absorbing films 3 can be arranged densely to improve electromagnetic wave absorption efficiency.

  A method of applying a magnetic field to the electromagnetic wave absorbing sheet 1 and magnetizing the electromagnetic wave absorbing film 3 in a certain direction can also be used. Thereby, the electromagnetic wave absorption efficiency of the electromagnetic wave absorbing film becomes better.

  In the electromagnetic wave absorbing sheet 1 described above, the electromagnetic wave absorbing film 3 positioned outside is separated from the peripheral edge of the insulating film 2, so that the electromagnetic wave absorbing film 3 is prevented from conducting with an external conductor. This separation distance is preferably 50 to 1000 μm, particularly preferably 100 to 500 μm. However, the electromagnetic wave absorbing film 3 may extend to the periphery of the insulating film 2.

  Next, an example of an electromagnetic wave absorbing sheet laminate formed by laminating an electromagnetic wave absorbing sheet in a plurality of layers will be described with reference to FIG. FIG. 4 (a) is a plan view showing a state before the four electromagnetic wave absorbing sheets 1 are overlaid, and FIG. 4 (b) is a diagram showing the state in which these four electromagnetic wave absorbing sheets 1 are overlaid. It is a longitudinal cross-sectional view along the long side direction of the absorption sheet.

  As shown in FIGS. 4 (a) and 4 (b), the above-described electromagnetic wave absorbing sheet 1 is laminated in a plurality of layers (four layers in the present embodiment), and these are joined together to form an electromagnetic wave absorbing sheet laminate. Is done.

  The method for joining the electromagnetic wave absorbing sheets 1 to each other is not particularly limited, but it is preferable that the insulating film 2 is made of a thermoplastic resin and the laminated layers of the electromagnetic wave absorbing sheets 1 are heated to thermocompression-bond each layer. Moreover, you may adhere | attach the electromagnetic wave absorption sheets 1 with an adhesive agent.

  The thickness of the electromagnetic wave absorbing sheet laminate is preferably 10 to 500 μm, particularly 20 to 150 μm, particularly 25 to 100 μm. Electromagnetic wave absorption efficiency improves that it is 25 micrometers or more. When it is 100 μm or less, the size and weight can be reduced.

  The above embodiment is an example of the present invention, and the present invention is not limited to the above embodiment.

  For example, in the above embodiment, the electromagnetic wave absorbing film 3 has a rectangular shape, but is not limited to this, and has an elongated shape in which the length a in the longitudinal direction is larger than the length b in the short direction. Any shape other than a rectangle may be used.

  Specifically, the electromagnetic wave absorbing film 3A may have an elliptical shape as shown in FIG. 5 of the electromagnetic wave absorbing sheet 1A. There may be. 6 may be a rhombic electromagnetic wave absorbing film 3B as shown in FIG. 6, a triangular electromagnetic wave absorbing film 3C as shown in FIG. 7, and a hexagonal electromagnetic wave absorbing film 3D as shown in FIG. Further, it may be a pentagon, a heptagon or more polygon, or a concave polygon. Triangular, quadrangular or polygonal corners may be curved.

  Here, the length a in the longitudinal direction means the length of a line segment (hereinafter referred to as a long line segment) that connects the two most distant points in the periphery of the electromagnetic wave absorbing film, and the length b in the short direction. Means the length of the largest width among the widths of the electromagnetic wave absorbing film in the direction perpendicular to the long line segment. However, as shown in FIG. 1 (c), when the electromagnetic wave absorbing film has a rectangular shape, the length a in the longitudinal direction means the length of the diagonal L, and the length b in the short direction. Means the width in the direction orthogonal to the diagonal L.

  In the electromagnetic wave absorbing sheet laminate of FIG. 4, four layers of the electromagnetic wave absorbing sheet 1 are laminated, but it may be two to three layers or five or more layers. Further, layers other than the electromagnetic wave absorbing sheet 1 may be laminated. For example, the insulating film 2 may be a heat dissipation sheet, or a film on which an antenna-shaped metal is printed.

  In the above embodiment, the electromagnetic wave absorbing film 3 is formed by sputtering. However, the present invention is not limited to this, and vacuum deposition methods such as an ion plating method, gravure printing, screen printing, ink jet printing, electrostatic printing. It may be formed by a printing method such as a dispenser or the like.

  In the electromagnetic wave absorbing sheet laminate of FIG. 4, one type of electromagnetic wave absorbing sheet 1 is laminated in a plurality of layers, but a plurality of types of electromagnetic wave absorbing sheets having different arrangement patterns of electromagnetic wave absorbing films may be laminated. This will be described with reference to FIG.

  FIG. 9 (a) is a plan view of the electromagnetic wave absorbing sheet 1B, and FIG. 9 (b) is an overlapping view of the electromagnetic wave absorbing sheet 1B of FIG. 9 (a) and the electromagnetic wave absorbing sheet 1 of FIG. It is a longitudinal cross-sectional view which shows the state cut | disconnected along the long side direction of this electromagnetic wave absorption sheet | seat 1,1B.

  The electromagnetic wave absorbing sheet 1B of FIG. 9 (a) is obtained by shifting the phase of the arrangement pattern of the electromagnetic wave absorbing film in the horizontal direction in the electromagnetic wave absorbing sheet 1 of FIG. 1 (a). Specifically, each row constituting the electromagnetic wave absorbing film group of the electromagnetic wave absorbing sheet 1B includes five electromagnetic wave absorbing films 3 arranged in the left-right direction at intervals and the left side of the leftmost electromagnetic wave absorbing film 3. The electromagnetic wave absorbing film 3E disposed at a distance from each other and the electromagnetic wave absorbing film 3E disposed at a right side of the rightmost electromagnetic wave absorbing film 3 at a distance. These left and right electromagnetic wave absorbing films 3 </ b> E have a long side length of approximately ½ compared to the electromagnetic wave absorbing film 3.

  As shown in FIG. 9 (b), the electromagnetic wave absorbing sheet 1B of FIG. 9 (a) and the electromagnetic wave absorbing sheet 1 of FIG. A sheet laminate is formed.

  As shown in FIG. 9 (b), the horizontal position of the gap between the electromagnetic wave absorbing films 3 in the first and third stage electromagnetic wave absorbing sheets 1 from the top is the second and fourth stage electromagnetic wave absorption from the top. The position of the gap between the electromagnetic wave absorbing films 3 and 3E in each of the sheets 1B is shifted from the left-right direction. For this reason, it is well prevented that the electromagnetic wave passes through the gap in the thickness direction of the electromagnetic wave absorbing sheet laminate.

  Note that the electromagnetic wave absorbing sheet 1B in FIG. 9 (a) is shifted only in the horizontal phase of the electromagnetic wave absorbing film as compared with the electromagnetic wave absorbing sheet 1 in FIG. 1, but the vertical phase is also shifted. May be. Thereby, the passage of electromagnetic waves is better prevented. Further, in FIG. 9 (b), the electromagnetic wave absorbing sheets 1, 1B having different phases are alternately laminated, but the present invention is not limited to this. For example, the electromagnetic wave absorbing sheets 1, 1, 1B, 1B from above are stacked. The electromagnetic wave absorbing sheets 1B, 1B, 1, 1 may be laminated in this order, the electromagnetic wave absorbing sheets 1B, 1, 1, 1B in this order, and the electromagnetic wave absorbing sheets 1, 1B, 1B, 1 in this order. Alternatively, the number of the electromagnetic wave absorbing sheet 1 and the electromagnetic wave absorbing sheet 1B may be different. For example, the electromagnetic wave absorbing sheets 1, 1, 1B, 1 may be laminated in this order from the top.

  In the electromagnetic wave absorbing sheet 1 of FIG. 1 (a), the arrangement patterns of the six rows constituting the electromagnetic wave absorbing film group are the same, but they may be different. For example, like the electromagnetic wave absorbing sheet 1C in FIG. 10, the second, fourth, and sixth rows from the top may be shifted in the horizontal direction.

  When manufacturing an electromagnetic wave absorbing sheet laminate in which the electromagnetic wave absorbing film is magnetized in a certain direction, an electromagnetic wave absorbing sheet in which the electromagnetic wave absorbing film is magnetized in a certain direction is prepared in advance, and these are laminated to form the electromagnetic wave absorbing sheet. It is good also as a laminated body. Moreover, after manufacturing the electromagnetic wave absorption sheet laminated body by laminating | stacking the electromagnetic wave absorption sheet in which the electromagnetic wave absorption film is not magnetized, you may magnetize this electromagnetic wave absorption sheet laminated body in a fixed direction.

  Hereinafter, the present invention will be described in detail using examples and comparative examples.

Examples 1-25
The electromagnetic wave absorbing sheet 1 shown in FIG. 1 was produced under the following sputtering conditions.

Target: Sendust (dimensions: 150 x 150 x 0.3 mm)
Sputtering voltage: Sputtering voltage of 1 to 1.5 kW
Sputtering atmosphere: Ar gas (flow rate 5-50 sccm)
Sputtering time: 60 to 600 seconds Sputtering pressure: 0.5 to 1.2 Pa
Deposition rate: 0.1-0.5 nm / s
The materials and dimensions of the obtained electromagnetic wave absorbing sheet 1 are as shown in Table 1.

  Four of the obtained electromagnetic wave absorbing sheets were superposed and thermocompression bonded under the following conditions to produce an electromagnetic wave absorbing sheet laminate.

Heating temperature: 130-200 ° C
Heating time: 30-180 seconds

Comparative Example 1
An electromagnetic wave absorbing sheet was manufactured in the same manner as in Examples 1 to 25 except that the directivity direction of the electromagnetic wave absorbing film was random. The materials and dimensions of the obtained electromagnetic wave absorbing sheet are as shown in Table 1.

  Four of the electromagnetic wave absorbing sheets were superposed and thermocompression bonded under the same conditions as in Examples 1 to 25 to produce an electromagnetic wave absorbing sheet laminate.

<Measurement of magnetic permeability>
About the obtained electromagnetic wave absorption sheet laminated body of Examples 1-25 and the comparative example 1, the insulating film was processed into the toroidal shape, this was set to the jig | tool, and the magnetic permeability was measured using the impedance analyzer. The results are shown in Table 1.

<Discussion>
Comparative Example 1 in which the films are randomly oriented has a low magnetic permeability of 5, whereas Examples 1 to 25 in which the films are oriented substantially in parallel have a good electromagnetic wave absorption effect with a magnetic permeability of 10 or more. Obtained. In particular, a / b is 1.0 to 2000 (Examples 2 to 5), b / c is 2.5 to 1000000 (Examples 8 to 12), and a / c is 5.0 to 2000000 (Examples 15 to 19). ), Those having an area ratio of 55 to 95% (Examples 22 to 24) had an excellent electromagnetic wave absorption effect with a magnetic permeability of 30 or more.

1, 1A, 1B, 1C Electromagnetic wave absorbing sheet 2 Insulating film 3, 3A, 3B, 3C, 3D, 3E Electromagnetic wave absorbing film 10 Mask 11 Opening 20 Target 21 Holder

Claims (17)

An electromagnetic wave absorbing sheet having an insulating film and a plurality of electromagnetic wave absorbing films formed at intervals on the surface of the insulating film,
The electromagnetic wave absorbing film has an elongated shape in which the length in the longitudinal direction is larger than the length in the short direction,
The electromagnetic wave absorbing sheet, wherein the plurality of electromagnetic wave absorbing films are substantially parallel to each other in the longitudinal direction.   2. The electromagnetic wave absorbing sheet according to claim 1, wherein the electromagnetic wave absorbing film is rectangular or elliptical.   3. The electromagnetic wave absorbing sheet according to claim 1, wherein the electromagnetic wave absorbing film has a ratio a / b of a length a in the longitudinal direction to a length b in the lateral direction of 1 to 2000. 4.   4. The electromagnetic wave absorption according to claim 1, wherein the electromagnetic wave absorbing film has a ratio b / c of a length b to a thickness c in the short side direction of 2.5 to 1,000,000. Sheet.   5. The electromagnetic wave absorbing sheet according to claim 1, wherein the electromagnetic wave absorbing film has a ratio a / c of a length a in the longitudinal direction to a thickness c of 5 to 2,000,000.   6. The electromagnetic wave absorbing sheet according to claim 1, wherein 50 to 95% of the area of the insulating film is covered with the electromagnetic wave absorbing film.   7. The electromagnetic wave absorbing sheet according to claim 1, wherein the insulating film is made of a synthetic resin.   8. The electromagnetic wave absorbing sheet according to claim 7, wherein the synthetic resin is a thermosetting resin, a thermoplastic resin, or a thermosetting resin.   The electromagnetic wave absorbing sheet according to claim 7 or 8, wherein the insulating film has a thickness of 1 to 200 µm.   10. The electromagnetic wave absorbing sheet according to claim 1, wherein the electromagnetic wave absorbing film is made of a thin film of a magnetic material.   The electromagnetic wave absorbing sheet according to claim 10, wherein the electromagnetic wave absorbing film is magnetized in a certain direction.   An electromagnetic wave absorbing sheet laminate comprising a plurality of layers of the electromagnetic wave absorbing sheet according to any one of claims 1 to 11.   The electromagnetic wave absorbing sheet laminate according to claim 12, wherein an arrangement pattern of the electromagnetic wave absorbing film in at least one electromagnetic wave absorbing sheet is different from an arrangement pattern of the electromagnetic wave absorbing film in the other at least one electromagnetic wave absorbing sheet.   14. The electromagnetic wave according to claim 13, wherein the arrangement pattern of the electromagnetic wave absorption film in each electromagnetic wave absorption sheet is an arrangement pattern in which the phase of the arrangement pattern of the electromagnetic wave absorption film in at least one other electromagnetic wave absorption sheet is shifted. Absorbent sheet laminate.   It is a method of manufacturing the electromagnetic wave absorbing sheet according to any one of claims 1 to 11, wherein the electromagnetic wave absorbing film is formed by sputtering with a mask placed on or facing the insulating film. A method for producing an electromagnetic wave absorbing sheet.   The member provided with the electromagnetic wave absorption sheet of any one of Claims 1 thru | or 11.   The member provided with the electromagnetic wave absorption sheet laminated body of any one of Claims 12 thru | or 14.

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