Electromagnetic wave shielding film

Abstract

An object of the present invention is to provide a novel electromagnetic wave shielding film capable of suppressing peeling caused by gas in an adhesive layer.SOLUTION: An electromagnetic wave shielding film comprising an adhesive layer having an adhesive surface to be adhered to an adherend, wherein a gap material having a gap into which a gas can flow is disposed in the adhesive layer.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an electromagnetic wave shielding film. [Background technology]

[0002] Conventionally, electromagnetic wave shielding films have been used as EMC countermeasures in electronic devices to provide a shield against electromagnetic waves that can become noise. Electromagnetic wave shielding films typically include an adhesive layer with an adhesive surface used for bonding to an adherend, and a film-like outer layer material that contacts the adhesive layer from the side opposite the adhesive surface. Known electromagnetic wave shielding films include those that have a shielding layer such as a metal foil on the outer layer material side, and those that contain a conductive filler in the adhesive layer, giving the adhesive layer itself the function of a shielding layer.

[0003] An example of an adherend for an electromagnetic wave shielding film is a printed circuit board, which typically includes a base film made of a polyimide resin, a circuit pattern formed on the base film, and a coverlay that protects the circuit pattern.

[0004] When an electromagnetic wave shielding film is bonded to a printed circuit board, a process of thermocompression bonding is performed in a state in which the electromagnetic wave shielding film is superimposed on the printed circuit board. Furthermore, components may be mounted on the printed circuit board to which the electromagnetic wave shielding film is bonded by a reflow process. The heat treatment in these processes generates gas from the adhesive layer of the electromagnetic wave shielding film, the base film of the printed circuit board, and the like, and it is believed that this gas causes delamination between the adhesive layer and the shielding layer and peeling of the adhesive layer from the printed circuit board.

[0005] Therefore, Patent Document 1 proposes forming a gap such as a slit in the adhesive layer to allow gas to escape. Patent Document 1 also describes a method for forming a slit, in which an adhesive composition is applied to copper foil that will serve as a shielding layer and dried to laminate the adhesive layer before slit formation on the copper foil, and then irradiates the adhesive layer with laser light to form a slit. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2021-174948 Summary of the Invention [Problem to be solved by the invention]

[0007] However, it is difficult to say that these types of measures have been fully implemented in electromagnetic wave shielding films, and it is desirable to provide new means that differ from conventional techniques.

[0008] In view of the above circumstances, an object of the present invention is to provide a novel electromagnetic wave shielding film that can suppress peeling caused by gas in the adhesive layer. [Means for solving the problem]

[0009] The present inventors have completed the present invention based on the idea that by using a porous material having voids that allow gas to flow in, voids resulting from the porous material can be imparted to the adhesive layer.

[0010] The electromagnetic wave shielding film according to the present invention is as follows. [1] an adhesive layer having an adhesive surface to be adhered to an adherend; An electromagnetic wave shielding film, wherein the adhesive layer is provided with a porous material having voids that allow gas to flow therethrough.

[0011] [2] The electromagnetic wave shielding film according to [1] above, wherein the void material has linear voids.

[0012] [3] the electromagnetic wave shielding film is in a strip shape, The electromagnetic wave shielding film according to [2] above, wherein the void material is arranged so that the voids extend in the longitudinal direction of the electromagnetic wave shielding film.

[0013] [4] The electromagnetic wave shielding film according to any one of the above [1] to [3], wherein the gap material forms one or more gaps extending in the length direction of the electromagnetic wave shielding film.

[0014] [5] The electromagnetic wave shielding film according to any one of the above [1] to [4], wherein the porous material is a facing material made of fiber.

[0015] [6] [5] The electromagnetic wave shielding film according to the above [5], wherein the thickness of the gap material is smaller than the thickness of the adhesive layer.

[0016] [7] The electromagnetic wave shielding film according to the above [5] or [6], wherein the gap material has electrical conductivity.

[0017] [8] The electromagnetic wave shielding film according to any one of the above [5] to [7], wherein the facing material is a nonwoven fabric.

[0018] [9] an outer layer material laminated on the adhesive layer from the side opposite to the adhesive surface, the outer layer material includes a shielding layer or a protective layer as an adjacent layer in contact with the adhesive layer, The electromagnetic wave shielding film according to any one of the above [1] to [8], wherein the adjacent layer has a second gap through which gas can flow. [Effects of the Invention]

[0019] According to the present invention, it is possible to provide a novel electromagnetic wave shielding film that can suppress peeling of the adhesive layer caused by gas. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a schematic cross-sectional view of an electromagnetic wave shielding film according to a first embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view of an electromagnetic wave shielding film according to a second embodiment. [Figure 3] FIG. 10 is a schematic cross-sectional view of an electromagnetic wave shielding film according to a third embodiment. [Figure 4] FIG. 2 is a schematic cross-sectional view showing one embodiment of an adhesive layer. [Figure 5] FIG. 1 is a schematic perspective view showing one embodiment of an adhesive layer, showing a portion in the length direction. [Figure 6] FIG. 1 is a schematic perspective view showing one embodiment of an adhesive layer, showing a portion in the length direction. [Figure 7] FIG. 1 is a manufacturing flow diagram of an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0021] A method for producing an electromagnetic wave shielding film according to an embodiment of the present invention will be described with reference to the drawings.

[0022] First, the electromagnetic wave shielding film, which is a product according to the present embodiment, will be described with reference to Figures 1 to 3. Note that Figure 1 shows a first embodiment, and in the second and third embodiments shown in Figures 2 and 3, the same reference numerals are used to designate the same components as in the first embodiment, and detailed descriptions thereof will be omitted.

[0023] The electromagnetic wave shielding film according to this embodiment is strip-shaped and is cut into pieces according to the size of the adherend surface. Such an electromagnetic wave shielding film may be wound up in a radially overlapping manner around the outer peripheral surface of a cylindrical core material such as a paper tube to form a roll. Hereinafter, the direction in which the electromagnetic wave shielding film extends will be referred to as the length direction, and the two directions perpendicular to the length direction will be referred to as the width direction and the thickness direction.

[0024] As shown in FIG. 1 , an electromagnetic wave shielding film 1a according to a first embodiment comprises an adhesive layer 11 that is adhered to an adherend such as a printed circuit board, and an outer layer material 12 that is laminated on the adhesive layer 11. Before use, the electromagnetic wave shielding film 1a is stored in the form of an electromagnetic wave shielding film 100 with a release film F superimposed thereon so as to cover the adhesive layer 11. That is, the release film F prevents foreign matter from adhering to the adhesive surface of the adhesive layer 11 before use, and prevents the adhesive surface from adhering to the back surface of the electromagnetic wave shielding film 1a (the surface of the shielding layer 121 in this embodiment) when the electromagnetic wave shielding film 1a is rolled up. The electromagnetic wave shielding film 1a is configured to be attached to an adherend by thermocompression bonding between the adhesive layer 11, which is exposed when the release film F is peeled off from the electromagnetic wave shielding film 100 with a release film, and the adherend, such as a printed circuit board.

[0025] The adhesive layer 11 has a first adhesive surface, which is the first surface that comes into contact with the adherend, and a second surface, which is the opposite surface to the first surface, that is adhered to the outer layer material 12 and forms the interface with the outer layer material 12.

[0026] The thickness of the adhesive layer is, for example, 0.5 μm or more and 20 μm or less.

[0027] The outer layer material 12 in the first embodiment is made of a shielding layer 121. That is, the electromagnetic wave shielding film 1a is provided with an outer layer material 12 having a single-layer structure made of a shielding layer 121. The outer layer material 12 has a laminated surface on one of its two surfaces, on which the adhesive layer is laminated. In the first embodiment, the shielding layer 121 is an adjacent layer that contacts the adhesive layer 11.

[0028] The shielding layer may be a metal layer made of metal, or a conductive layer in which a conductive filler is filled in a binder resin. The metal layer may be allowed to contain unavoidable impurities that do not affect the shielding properties. Such a metal layer may be composed of a metal foil formed by rolling, or may be a deposited film formed by a deposition method such as electroplating, vacuum deposition, sputtering, or CVD. Examples of materials for forming the shielding layer include copper, nickel, silver, tin, gold, palladium, aluminum, chromium, titanium, zinc, and alloys of two or more of these.

[0029] The thickness of the shield layer is, for example, not less than 0.1 μm and not more than 20 μm.

[0030] 2, an electromagnetic wave shielding film 1b according to a second embodiment includes an outer layer material 12 made up of a shielding layer 121 laminated on an adhesive layer 11 and a protective layer 122 laminated on the shielding layer 121. That is, the electromagnetic wave shielding film 1b includes an outer layer material 12 with a multilayer structure made up of the shielding layer 121 and the protective layer 122. In the second embodiment, the shielding layer 121 is an adjacent layer that contacts the adhesive layer 11.

[0031] The protective layer is insulating (for example, has a volume resistivity of 1×10 at room temperature (23° C.) 12 The protective layer may be a single layer, or may be composed of two or more layers with different compositions or physical properties.

[0032] The protective layer may be formed from an insulating resin composition, which may contain a thermoplastic resin, a curable resin that is cured by heat or light, a polymerization initiator, a curing agent, etc.

[0033] Examples of the thermoplastic resin for the protective layer include polyester resin, polyethylene resin, polypropylene resin, polystyrene resin, vinyl acetate resin, polyamide resin, polyimide resin, and acrylic resin. Examples of the thermosetting resin include epoxy resin, urethane resin, acrylic resin, melamine resin, phenol resin, and polyester resin (unsaturated polyester resin).

[0034] The protective layer has a thickness of, for example, 1 μm or more and 15 μm or less. When the protective layer is composed of two or more layers, the thickness of each protective layer is, for example, 0.5 μm or more and 12 μm or less.

[0035] Next, as shown in Fig. 3, an electromagnetic wave shielding film 1c according to a third embodiment includes an outer layer material 12 made up of an adhesive layer 11 and a protective layer 122 laminated on the adhesive layer 11. That is, the electromagnetic wave shielding film 1c includes an outer layer material 12 with a single-layer structure made up of the protective layer 122. The adhesive layer 11 in the third embodiment is the conductive adhesive layer. In the third embodiment, the protective layer 122 is an adjacent layer that contacts the adhesive layer 11.

[0036] The adhesive layer of each embodiment includes a void material having voids that allow gas to flow therethrough, and is composed of the void material and an adhesive material. The adhesive material includes a conductive filler and a binder resin and can be used to establish electrical continuity between the shielding layer and the ground circuit of the printed circuit board. That is, the adhesive layer can be a conductive adhesive layer. Alternatively, the adhesive layer may not include a conductive filler and may simply be an insulating layer used to bond the shielding layer to the printed circuit board.

[0037] Examples of the conductive filler include copper particles, silver particles, nickel particles, silver-coated copper particles, gold-coated copper particles, silver-coated nickel particles, gold-coated nickel particles, silver-coated alloy particles, carbon fillers, and metal-coated resin particles.

[0038] The binder resin may be a curable resin or a thermoplastic resin. Examples of the curable resin include phenolic resins, epoxy resins, urethane resins, melamine resins, and alkyd resins. Examples of the thermoplastic resin include polyester resins, polyolefin resins, polystyrene resins, vinyl acetate resins, polyimide resins, polyamide resins, and acrylic resins. The curable resin has reaction curing properties. The curing reaction of the curable resin may be accelerated by, for example, thermal energy or by energy rays such as ultraviolet rays or electron beams. That is, the curable resin may be a thermosetting resin or a photocurable resin.

[0039] When the adhesive layer is a conductive adhesive layer, the content of the conductive filler in the conductive adhesive layer can be, for example, 10% by mass or more. The content here may be 30% by mass or more, or 50% by mass or more. Furthermore, the content here may be 60% by mass or more, or 70% by mass or more. The content here may be 95% by mass or less, 90% by mass or less, or 85% by mass or less.

[0040] The porous material is a material having pores that allow gas to flow in. The shape of the porous material is not particularly limited and may be granular, linear, or film-like. The porous material may be a capsule-like material without openings on the surface, as long as it is made of a material with excellent gas permeability. The porous material preferably has one or more pores, at least some of which are open to the surface of the porous material.

[0041] The porous material may be, for example, porous particles such as activated carbon, silica gel, or zeolite. The porous material may be, for example, a wire material having voids, such as hollow fibers, multifilament yarns, or spun yarns. The porous material may be, for example, a facing material having voids. The facing material may be, for example, a nonwoven fabric, woven fabric, or knitted fabric. When the porous material is a wire material such as hollow fibers or multifilament yarns, or a facing material obtained by weaving such a wire material, voids extending linearly in the length direction of the wire material can be introduced into the adhesive layer. When the porous material is a woven fabric or nonwoven fabric obtained by weaving wire material such as hollow fibers or multifilament yarns, not only can the voids in the wire material itself be used to store gas, but the voids between the wire material can also be used to store gas.

[0042] Furthermore, even if gas is generated from the adhesive layer or the base film of the printed circuit board after the electromagnetic wave shielding film is adhered to the printed circuit board, the voids in the porous material can accommodate some of the gas, preventing the gas pressure from rising to the point where peeling occurs at the interface between the adhesive layer and the printed circuit board or the interface between the adhesive layer and an adjacent layer. In such cases, it is difficult to predict in advance where gas will be generated, so porous materials with linear voids are advantageous in that they can accommodate gas over a wider area than granular porous materials. Furthermore, if the porous material is a surface material, it can be even more advantageous for accommodating gas.

[0043] Furthermore, in an embodiment in which the electromagnetic wave shielding film is strip-shaped and the porous material is arranged so that the voids extend in the longitudinal direction, the porous material is likely to be cut when the film is diced to fit the adherend. In other words, in such an electromagnetic wave shielding film, the cut edges of the porous material are likely to appear on the outer periphery when the film is diced, and generated gas can be guided to the outer periphery and released to the outside through the cut edges, thereby further preventing interfacial peeling due to gas generation.

[0044] 4, the void material 20 may be contained so as to be dispersed in the adhesive layer 11. In such an embodiment, the void material is preferably the porous particles.

[0045] The porous material is preferably a fibrous facing material such as a nonwoven fabric. In particular, nonwoven fabric has voids that are connected in the planar and thickness directions, and the proportion of voids is higher than that of a single thread. Furthermore, since fibrous facing materials are relatively soft, they can deform to conform to the surface of the adherend when pressed to adhere the electromagnetic wave shielding film to the adherend. Therefore, it is thought that fibrous facing materials do not hinder the adhesion of the adhesive layer. From the viewpoint of being able to form a micro-order adhesive layer relatively inexpensively, the fibrous facing material is preferably a nonwoven fabric.

[0046] The gap material may be conductive. Using a conductive face material as the gap material can be expected to exhibit a higher shielding effect than using a face material that is not conductive. Examples of such gap materials include nonwoven fabrics made of conductive fibers (i.e., conductive nonwoven fabrics) and woven or knitted fabrics made of conductive yarns. When such a face material is used, the adhesive layer is preferably a conductive adhesive layer. The use of a conductive face material facilitates electrical connection between the shielding layer and the ground circuit in applications where a printed circuit board equipped with a ground circuit is used as the adherend and the shielding layer is electrically connected via the conductive adhesive layer. Furthermore, in an embodiment (third embodiment) in which the adhesive layer also functions as a shielding layer, the gap material itself can exhibit shielding properties, thereby improving the reliability of the electromagnetic wave shielding film.

[0047] The thickness of the void material is preferably smaller than the thickness of the adhesive layer. In other words, it is preferable that the void material is not exposed at the adhesive surface of the adhesive layer. Furthermore, it is preferable that the adhesive layer contains the void material so that no protrusions protruding from the adhesive surface are formed. To achieve this preferred embodiment, the nonwoven fabric may be made of ultrafine fibers having a fineness of 0.5 denier or less. The nonwoven fabric may be, for example, a thermal bonded nonwoven fabric or a meltblown nonwoven fabric, since relatively thin ones are easily available.

[0048] When the face material is a nonwoven fabric, the thickness of the face material can be measured by the measurement method described in JIS L 1913. When the face material is a woven fabric or knitted fabric, the thickness can be measured by the measurement method described in JIS L 1096. On the other hand, the thickness of the adhesive layer can be determined by randomly selecting 10 locations on the adhesive layer, measuring the thickness of the adhesive layer at each location, and averaging the measurements.

[0049] The weight per unit area of ​​the surface material is 1 g / m 2 More than 100g / m 2 Preferably, it is 15 g / m or less. 2 More than 60g / m 2 It is more preferable that the following is satisfied: When the face material is a nonwoven fabric, the basis weight can be measured by the measurement method described in JIS L1913. When the face material is a woven fabric or knitted fabric, the basis weight can be measured by the measurement method described in JIS L1096.

[0050] The porosity of the nonwoven fabric is preferably 40% to 95%, and more preferably 60% to 85%. This allows sufficient flow of gas generated when the electromagnetic wave shielding film is pressure-bonded to the adherend, and prevents the adhesive layer from interfering with the adhesion of the adhesive layer to the adherend. The porosity here can be calculated using the following formula: Porosity (%) = 100 - [(basis weight) / (thickness x fiber density)] x 100

[0051] Considering that the electromagnetic wave shielding film may be adhered to a printed circuit board and passed through a reflow oven, the gap material is preferably composed of fibers with excellent heat resistance. The gap material may contain inorganic fibers such as alumina fibers, rock wool, basalt fibers, and metal fibers. The gap material may contain fibers with excellent heat deformation resistance such as aromatic polyamide fibers, polyimide fibers, polyamideimide fibers, polyetherimide fibers, polyetheretherketone fibers, polyphenylene sulfide fibers, polysulfone fibers, polyethersulfone fibers, fluororesin fibers, and cellulose fibers.

[0052] In one embodiment of the adhesive layer 11 shown in FIG. 5 , the void material 20 is included in the adhesive layer 11 to form a plurality of voids 21 extending in a length direction D1, which is a first direction. The void material 20 is also included in the adhesive layer 11 to form a plurality of voids 22 extending in a width direction D2, which is a second direction intersecting the first direction. The plurality of voids 21 and 22 are formed to intersect. That is, the void material 20 is included in the adhesive layer 11 to form lattice-shaped voids. As a result, the void material 20 forms voids that are continuous in both the length direction D1 and the width direction D2 in the adhesive layer 11. The adhesive layer 11 also has a plurality of adhesive portions 111 separated by the voids in both the length direction D1 and the width direction D2. In this embodiment, the plurality of voids 22 form the side surfaces of the adhesive layer 11. That is, the void material 20 is exposed on the side surfaces of the adhesive layer 11. This allows gas to be released from the side surface through the gap material 20. In this embodiment, the gap material is preferably the wire material or the surface material.

[0053] In one embodiment of the adhesive layer 11 shown in FIG. 6, the void material 20 is contained in the adhesive layer 11 so as to form a plurality of voids 21 extending only in the length direction D1. As a result, the void material 20 forms a plurality of voids in the adhesive layer 11 that are continuous only in the length direction D1. The adhesive layer 11 also has a plurality of adhesive portions 111 that extend only in the width direction D2. Such an adhesive layer 11 is easy to form continuously. Therefore, an electromagnetic wave shielding film including such an adhesive layer 11 is excellent in mass productivity. In such an embodiment, the void material is preferably the wire material or the surface material.

[0054] In yet another aspect, the void material may be included in the adhesive layer so as to form a plurality of voids extending only in the width direction, thereby forming a plurality of voids in the adhesive layer that are continuous only in the length direction, and the adhesive layer has a plurality of adhesive portions extending only in the length direction.

[0055] The electromagnetic wave shielding film may also have a plurality of second voids that allow gas to flow into the shielding layer or the protective layer that is the adjacent layer to the adhesive layer. The plurality of second voids may be formed, for example, in a columnar shape extending in the thickness direction of the shielding layer or the protective layer. Each second void may penetrate the shielding layer or the protective layer in the thickness direction. Furthermore, at least some of the plurality of second voids may be connected to at least some of the void material in the adhesive layer.

[0056] Next, a method for producing the electromagnetic wave shielding film according to this embodiment will be described.

[0057] In the manufacturing method according to this embodiment, in addition to the void material, a liquid adhesive composition for forming the adhesive layer is prepared as a coating liquid. In the manufacturing method according to this embodiment, a method of applying the coating liquid to a release film to form an adhesive layer on the release film and then transferring the adhesive layer to an outer layer material, or a method of applying the coating liquid to an outer layer material to form an adhesive layer can be employed.

[0058] The release film, outer layer material, and void material used in the production are preferably in strip form, which is suitable for mass production.

[0059] Taking the example of using a long strip of nonwoven fabric as the void material, to produce an electromagnetic wave shielding film, first, a coating liquid is applied to a release film to form a coating film on the release film (first coating). Next, a nonwoven fabric is placed on top of the coating film, and another coating liquid is applied to the nonwoven fabric (second coating). The coating liquid is then dried to form an adhesive layer containing the void material on the release film. The outer layer material and the adhesive layer are then bonded together to produce an electromagnetic wave shielding film. If necessary, a step of drying the coating film formed by the first coating may be provided between the first coating and the second coating. The coating film formed by the first coating may be dried before the nonwoven fabric is placed on top of the coating film.

[0060] In another embodiment, the coating liquid may be applied to an outer layer material instead of a release film. Specifically, first, the coating liquid is applied to the outer layer material to form a coating film on the outer layer material (shielding layer) (primary coating). Next, a nonwoven fabric is placed on top of the coating film, and the coating liquid is further applied to the nonwoven fabric (secondary coating). The coating liquid is then dried to form an adhesive layer containing a void material on the outer layer material, thereby producing an electromagnetic wave shielding film. In this case, too, if necessary, a step of drying the coating film formed by the primary coating may be provided between the primary coating and the secondary coating, and the drying of the coating film formed by the primary coating may be carried out before the nonwoven fabric is placed on top.

[0061] In yet another embodiment, a coating film may be formed on each of the outer layer material and the release film, and a nonwoven fabric may be sandwiched between them and integrated with a nip roll or the like to produce an electromagnetic wave shielding film.

[0062] The adhesive layer of the electromagnetic wave shielding film can also be formed by a single coating process, as in the embodiment shown below.

[0063] In the manufacturing method of this aspect, the first release film is pulled out from the roll as a raw film, and the adhesive layer and / or the outer layer material are formed on the first release film as it moves in the length direction, thereby obtaining the roll of the electromagnetic wave shielding film. That is, the manufacturing method of this embodiment employs a roll-to-roll method.

[0064] 7, the manufacturing method of this embodiment includes an adhesive layer-forming step P1 for forming the adhesive layer. The adhesive layer-forming step P1 includes a coating step P11 for forming a coating film of the adhesive composition while arranging the void material on the surface of the first release film, and a drying step P12 for removing the solvent from the adhesive composition by heating to convert it into the adhesive portion and obtain the adhesive layer.

[0065] The first release film may be a commonly used one, such as a resin film including a polyethylene terephthalate (PET) film, a polyethylene film, a polypropylene film, etc. The release film may also be a resin film whose surface is coated with a release agent such as a fluorine-based release agent or a long-chain alkyl acrylate-based release agent, or a paper film.

[0066] The adhesive composition used in the coating step contains the binder resin, and optionally the conductive particles and a solvent, such as one or more of toluene, acetone, methyl ethyl ketone, methanol, ethanol, propanol, ethyl acetate, propyl acetate, butyl acetate, and dimethylformamide.

[0067] In the coating process, the porous material may be pre-fixed to the first release film, or the strip-shaped porous material may be rolled up and superimposed on the first release film while being pulled out from the roll.

[0068] In the coating process, the adhesive composition is applied to the porous material while maintaining the voids originating from the porous material. Thus, in the coating process, it is necessary to suppress the filling of the voids with the adhesive composition. Therefore, in the coating process, it is preferable to adjust the viscosity of the adhesive composition. In addition, the adhesive composition may be solventless.

[0069] The coating step preferably uses a coating device, such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a lip coater, a dip roll coater, a bar coater, a knife coater, a spray coater, a comma coater, a direct coater, or a slot die coater.

[0070] Specifically, a coating device capable of forming a coating layer on the surface of the release film without contact is preferred over a roll coater, which forms a coating film by contacting a portion such as the periphery of the release film with the surface. Examples of such a coating device include a slot die coater. A non-contact coating device prevents the voids in the porous member from being crushed, making it easier to form voids that allow gas to flow in.

[0071] In the adhesive layer forming step of this embodiment, a coating layer having a thickness equal to or greater than the thickness of the void member (the height of the void portion) may be formed in the coating step, thereby forming an adhesive layer whose adhesion to the adherend is less likely to be hindered by the void material.

[0072] In the drying step, the solvent contained in the adhesive composition is removed by heating, and the adhesive composition is converted into the adhesive material to obtain an adhesive layer. Furthermore, in the drying step, the adhesive composition may be semi-cured into the adhesive material. The semi-cured adhesive material can retain the void material, thereby preventing the void material from separating from the release film and preventing components such as fibers of the void material from falling off.

[0073] Next, as shown in FIG. 7, the manufacturing method of this embodiment includes a lamination step P3, which is the step following the drying step P12, in which at least one layer of the shielding layer and the protective layer as the outer layer material is laminated onto the adhesive layer.

[0074] In the lamination process, the outer layer material may be formed on a second release film, which is a new material, and the adhesive layer may be transferred from the first release film to the outer layer material of the second release film. Here, when slits are formed by irradiating laser light onto an adhesive layer with an adjacent shielding or protective layer laminated thereon before slit formation, as in conventional technology, there is a risk of damaging the adjacent layer with the laser light. This risk is particularly high when the adhesive layer is thin, such as on the order of microns. In contrast, in this embodiment, an adhesive layer having a void material that replaces the slits can be laminated on the adjacent layer, thereby suppressing damage to the adjacent layer as in conventional technology.

[0075] The second release film is preferably used as a release film for the electromagnetic wave shielding film.

[0076] In forming the shield layer, a metal foil may be formed by rolling, or a deposited film may be formed by a deposition method such as electrolytic plating, vacuum deposition, sputtering, or CVD.

[0077] The protective layer may be formed by forming a coating film using a coating liquid containing the above components and, if necessary, a solvent, and then curing the coating film by heating or irradiating it with light.

[0078] Furthermore, the manufacturing method of this embodiment includes a winding step P3, which follows the lamination step P2 and produces a roll body in which the adhesive layer is disposed on the inside and the second release film is disposed on the outside, as shown in Fig. 7. In order to prevent blocking in the roll body, it is preferable that a plurality of convex portions are formed on the back surface of the second release film (the surface opposite to the surface on which the shielding layer or protective layer is formed).

[0079] Although the above embodiments have been shown as examples, the electromagnetic wave shielding film according to the present invention is not limited to the configurations of the above embodiments. Furthermore, the electromagnetic wave shielding film according to the present invention is not limited by the above-described effects. The electromagnetic wave shielding film according to the present invention can be modified in various ways without departing from the gist of the present invention. [Explanation of symbols]

[0080] 1a, 1b, 1c: electromagnetic wave shielding film, 11: adhesive layer, 111: adhesive portion, 12: outer layer material, 121: shielding layer, 122: protective layer, 20: gap material, 21: gap portion, 100: electromagnetic wave shielding film with release film, F: release film, P1: adhesive layer forming step, P11: coating step, P12: drying step, P2: lamination step, P3: winding step

Claims

1. an adhesive layer having an adhesive surface to be adhered to an adherend; An electromagnetic wave shielding film, wherein the adhesive layer is provided with a porous material having voids that allow gas to flow therethrough.

2. The electromagnetic wave shielding film according to claim 1 , wherein the void material has linear voids.

3. the electromagnetic wave shielding film is in a strip shape, The electromagnetic wave shielding film according to claim 2 , wherein the void material is arranged so that the voids extend in the longitudinal direction of the electromagnetic wave shielding film.

4. The electromagnetic wave shielding film according to claim 3 , wherein the void material forms one or more voids extending in the longitudinal direction of the electromagnetic wave shielding film.

5. The electromagnetic wave shielding film according to claim 1 , wherein the gap material is a fibrous facing material.

6. The electromagnetic wave shielding film according to claim 5 , wherein the thickness of the gap material is smaller than the thickness of the adhesive layer.

7. The electromagnetic wave shielding film according to claim 5 , wherein the gap material is electrically conductive.

8. The electromagnetic wave shielding film according to claim 5 , wherein the facing material is a nonwoven fabric.

9. an outer layer material laminated on the adhesive layer from the side opposite to the adhesive surface, the outer layer material includes a shielding layer or a protective layer as an adjacent layer in contact with the adhesive layer, The electromagnetic wave shielding film according to claim 1 , wherein the adjacent layer has a second gap through which gas can flow.

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