Electromagnetic wave shielding film

Abstract

Provided is an electromagnetic wave shielding film in which both the surface covering property and scratch resistance of a protective layer are sufficiently high. This electromagnetic wave shielding film is characterized by being provided with: a protective layer having a first main surface and a second main surface facing the first main surface; and a shield layer disposed on the second main surface of the protective layer, the expansion area ratio Sdr of the interface of the first main surface being 75.0-250%.

Description

Technical Field

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

[0002] Conventionally, for example, an electromagnetic wave shielding film is attached to a printed circuit board such as a flexible printed circuit board (FPC) to shield electromagnetic waves from the outside.

[0003] As a method for shielding a printed circuit board, there is known a method in which an electromagnetic wave shielding film having a protective layer and a shielding layer is attached to a printed circuit board under heating and pressure to form a shielded printed circuit board.

[0004] Furthermore, a base film made of polyethylene terephthalate (PET) resin or the like is disposed on the surface of the protective layer of the electromagnetic wave shielding film in order to protect the protective layer from scratches and foreign matter.

[0005] After the electromagnetic wave shielding film is attached to the printed circuit board, the base film is peeled off.

[0006] After the base film is peeled off, when the electromagnetic wave shielding film is touched with bare hands, fingerprints and dirt adhere to the protective layer of the electromagnetic wave shielding film, which causes a problem of poor appearance.

[0007] In order to solve such a problem, Patent Documents 1 and 2 form irregularities on the surface of the protective layer of the electromagnetic wave shielding film so that fingerprints, dirt, etc. become less noticeable on the protective layer.

[0008] That is, Patent Document 1 discloses an electromagnetic wave shielding film including an insulating layer and a shielding layer, wherein the insulating layer has a surface having a three-dimensional arithmetic mean surface roughness Sa of 0.8 μm or more.

[0009] Patent Document 2 discloses an electromagnetic wave shielding film including an insulating layer and a shielding layer, wherein the maximum peak height Sp of the surface of the insulating layer is 8.0 μm or more.

[0010] In addition, when an electromagnetic wave shielding film is pasted on a printed wiring substrate having a base layer, a circuit pattern formed of copper foil formed on the base layer, and a covering layer for protecting the circuit pattern, the circuit pattern of the printed wiring substrate may float on the surface of the electromagnetic wave shielding film due to reflection of light, etc., and sometimes sufficient covering power may not be obtained.

[0011] Patent Document 3 discloses an electromagnetic wave shielding film having improved shielding properties.

[0012] That is, Patent Document 3 discloses an electromagnetic wave shielding film including an insulating protective layer and a conductive adhesive layer, wherein the insulating protective layer has a glossiness of less than 15 at 85°.

[0013] Prior art literature

[0014] Patent Literature

[0015] Patent Document 1: Japanese Patent No. 6783205

[0016] Patent Document 2: Japanese Patent Application Publication No. 2021-010032

[0017] Patent Document 3: Japanese Patent No. 6863908 Summary of the invention

[0018] Problem that the invention aims to solve

[0019] In Patent Documents 1 and 2, the distance from the bottom to the top of the concavo-convex on the surface of the insulating layer (protective layer) is extended, so that fingerprints, dirt, etc. become less noticeable in the insulating layer (protective layer). In addition, in Patent Document 3, the surface roughness of the insulating protective layer (protective layer) to which the concavo-convex on the surface of the release film is transferred is increased, thereby improving the hiding property.

[0020] In such an insulating layer (protective layer), the tip of the convex portion is thin and easily weakened. Therefore, if there is an impact on the surface of the insulating layer (protective layer), part of the convex portion is easily damaged, and thus scratches are easily generated on the surface of the insulating layer (protective layer). That is, in the inventions described in Patent Documents 1, 2, and 3, there is a problem that the scratch resistance of the surface of the insulating layer (protective layer) is low.

[0021] In the inventions of Patent Document 1, Patent Document 2 or Patent Document 3, the following methods are considered as methods for improving the scratch resistance of the insulating layer (protective layer): a method of reducing the three-dimensional arithmetic mean surface roughness Sa of the surface of the insulating layer (protective layer); a method of reducing the maximum peak height Sp of the surface of the insulating layer (protective layer), but in this case, the covering property of the surface of the insulating layer (protective layer) becomes insufficient.

[0022] That is, in the inventions of Patent Document 1, Patent Document 2, or Patent Document 3, the hiding power and scratch resistance of the surface of the insulating layer (protective layer) are in a trade-off relationship, and it is not easy to achieve both hiding power and scratch resistance in these inventions.

[0023] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an electromagnetic shielding film having a protective layer with sufficiently high hiding power and scratch resistance on the surface.

[0024] Solutions for solving problems

[0025] The present inventors have found that both hiding power and scratch resistance can be achieved when the interface expansion area ratio Sdr or the root mean square slope Sdq on the surface of the protective layer is within a predetermined range, and have completed the present invention.

[0026] That is, the electromagnetic wave shielding film of the present invention is characterized in that it comprises: a protective layer having a first main surface and a second main surface opposite to the above-mentioned first main surface; and a shielding layer arranged on the second main surface of the above-mentioned protective layer, and the expansion area ratio Sdr of the interface of the above-mentioned first main surface is 75.0~250%.

[0027] In the electromagnetic wave shielding film of the present invention, when the expansion area ratio Sdr of the interface of the first main surface is 75.0 to 250%, the distance from the bottom to the top of the concave-convex of the first main surface and the density of the concave-convex become appropriate ranges. Therefore, the hiding power and scratch resistance of the first main surface of the protective layer become high.

[0028] When the expansion area ratio Sdr of the interface of the first main surface is less than 75.0%, the covering property decreases.

[0029] When the expansion area ratio Sdr of the interface of the first main surface exceeds 250%, the scratch resistance decreases.

[0030] In addition, another embodiment of the electromagnetic wave shielding film of the present invention is characterized in that it comprises: a protective layer having a first main surface and a second main surface opposite to the above-mentioned first main surface; and a shielding layer arranged on the second main surface of the above-mentioned protective layer, and the root mean square slope Sdq of the above-mentioned first main surface is 1.50~2.70.

[0031] In the electromagnetic shielding film of the present invention, when the root mean square slope Sdq of the first main surface is 1.50 to 2.70, the distance from the bottom to the top of the concavities and convexities of the first main surface and the density of the concavities and convexities are in an appropriate range. Therefore, the hiding power and scratch resistance of the first main surface of the protective layer are improved.

[0032] When the root mean square slope Sdq of the first main surface is less than 1.50, the hiding power decreases.

[0033] When the root mean square slope Sdq of the first main surface exceeds 2.70, the scratch resistance decreases.

[0034] In the electromagnetic shielding film of the present invention, it is preferred that the minimum autocorrelation length Sal of the first main surface is 2.5 to 10.0 μm.

[0035] In the electromagnetic shielding film satisfying such parameters, the fineness of the irregularities on the first main surface of the protective layer becomes appropriate. Therefore, the first main surface of the protective layer has high hiding power and high scratch resistance.

[0036] In the electromagnetic shielding film of the present invention, it is preferred that an arithmetic mean height Sa of the first main surface is not less than 0.3 μm and less than 0.8 μm.

[0037] In the electromagnetic wave shielding film satisfying such parameters, the distance from the bottom to the top of the concave-convex of the first main surface of the protective layer is short. Generally, when the distance from the bottom to the top of the concave-convex of the first main surface of the protective layer is short, the covering property of the first main surface of the protective layer tends to be low.

[0038] However, when the extended area ratio Sdr of the interface of the first main surface is 75.0 to 250%, or when the root mean square slope Sdq of the first main surface is 1.50 to 2.70, the covering property of the first main surface of the protective layer is sufficiently high.

[0039] In the electromagnetic shielding film of the present invention, it is preferred that the 60° glossiness of the first main surface is 5.0 or less.

[0040] Furthermore, in the electromagnetic shielding film of the present invention, it is preferred that the 85° glossiness of the first main surface is 60.0 or less.

[0041] In the electromagnetic shielding film of the present invention, when the 60° glossiness or 85° glossiness is within the above range, the hiding power of the first main surface of the protective layer of the electromagnetic shielding film becomes sufficiently high.

[0042] In the electromagnetic shielding film of the present invention, the shielding layer may be formed of a metal layer, and a conductive adhesive layer may be disposed on a principal surface of the metal layer opposite to a principal surface in contact with the protective layer.

[0043] Furthermore, in the electromagnetic shielding film of the present invention, the shielding layer may be formed of a conductive adhesive layer.

[0044] Even if the shielding layer is configured in any of the above-described aspects, it is possible to appropriately shield electromagnetic waves.

[0045] In the electromagnetic shielding film of the present invention, it is preferred that a matte layer is further disposed on the first main surface of the protective layer, and a base film is disposed on a main surface of the matte layer opposite to a main surface in contact with the protective layer.

[0046] When manufacturing the electromagnetic wave shielding film of the present invention, the concavity and convexity formed on the matte layer is transferred to the first main surface of the protective layer, thereby forming the concavity and convexity on the first main surface of the protective layer. Therefore, by adjusting the concavity and convexity of the matte layer, the expansion area ratio Sdr or the root mean square slope Sdq of the interface of the first main surface of the protective layer can be within a specified range.

[0047] Furthermore, if a base film is disposed on the electromagnetic shielding film, the first main surface of the protective layer can be protected from impact, etc. Therefore, when the electromagnetic shielding film is conveyed, the protective layer of the electromagnetic shielding film can be prevented from being scratched.

[0048] Effects of the Invention

[0049] According to the present invention, it is possible to provide an electromagnetic shielding film in which both the hiding power and the scratch resistance of the surface of the protective layer are sufficiently high. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a cross-sectional view schematically showing an example of the cross section of the electromagnetic shielding film according to the first embodiment of the present invention.

[0051] Figure 2 This is a cross-sectional view schematically showing an example of a cross section of an electromagnetic shielding film according to another aspect of the first embodiment of the present invention.

[0052] Figure 3 It is a cross-sectional view schematically showing an example of a cross section of the electromagnetic wave shielding film according to the first embodiment of the present invention, that is, an electromagnetic wave shielding film having a matte layer and a base film.

[0053] Figure 4A This is a cross-sectional view schematically showing an example of a state in which the electromagnetic shielding film according to the first embodiment of the present invention is attached to a printed circuit board.

[0054] Figure 4B This is a cross-sectional view schematically showing an example of a cross section of a shield printed circuit board using the electromagnetic shield film according to the first embodiment of the present invention.

[0055] Figure 5 This is a process diagram schematically showing an example of a matte layer forming step in the method for producing the electromagnetic shielding film according to the first embodiment of the present invention.

[0056] Figure 6 This is a process diagram schematically showing an example of a protective layer forming step in the method for producing the electromagnetic shielding film according to the first embodiment of the present invention.

[0057] Figure 7 This is a process diagram schematically showing an example of a metal layer forming step in the method for producing the electromagnetic shielding film according to the first embodiment of the present invention.

[0058] Figure 8 This is a process diagram schematically showing an example of a conductive adhesive layer forming step in the method for producing the electromagnetic shielding film according to the first embodiment of the present invention.

[0059] Fig.9AThis is a photograph showing the state of the surface of the protective layer of the electromagnetic shielding film which serves as a reference for score 6 in the evaluation of scratch resistance.

[0060] Fig. 9B This is a photograph showing the state of the surface of the protective layer of the electromagnetic shielding film which serves as a reference for score 5 in the evaluation of scratch resistance.

[0061] Fig. 9C This is a photograph showing the state of the surface of the protective layer of the electromagnetic shielding film which serves as a reference for score 4 in the evaluation of scratch resistance.

[0062] Fig.9D This is a photograph showing the state of the surface of the protective layer of the electromagnetic shielding film which serves as a reference for score 3 in the evaluation of scratch resistance.

[0063] Fig.9E This is a photograph showing the state of the surface of the protective layer of the electromagnetic shielding film which serves as a basis for score 2 in the evaluation of scratch resistance.

[0064] Fig.9F This is a photograph showing the state of the surface of the protective layer of the electromagnetic shielding film which serves as a reference for score 1 in the evaluation of scratch resistance.

[0065] Fig. 10A This is a photograph of the first main surface of the protective layer, which serves as a criterion for "excellent (⊚)" in judging the hiding power of the first main surface of the protective layer of the magnetic wave shielding film.

[0066] Fig. 10B This is a photograph of the surface of the protective layer which serves as a standard for "good (0)" in judging the hiding power of the first main surface in the protective layer of the electromagnetic wave shielding film.

[0067] Fig. 10C This is a photograph of the first main surface of the protective layer, which serves as a criterion for "acceptable (△)" in judging the hiding power of the first main surface of the protective layer of the electromagnetic wave shielding film. DETAILED DESCRIPTION

[0068] Hereinafter, the electromagnetic wave shielding film of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be applied by appropriately changing the embodiments within the scope of the present invention.

[0069] (First embodiment)

[0070] Figure 1 It is a cross-sectional view schematically showing an example of the cross section of the electromagnetic shielding film according to the first embodiment of the present invention.

[0071] Figure 1The electromagnetic shielding film 1 shown includes: a protective layer 10 having a first main surface 10 a and a second main surface 10 b facing the first main surface 10 a ; and a shielding layer 20 arranged on the second main surface 10 b of the protective layer 10 .

[0072] In the electromagnetic shielding film 1 , the shielding layer 20 is formed of a metal layer, and a conductive adhesive layer 30 is disposed on a main surface of the metal layer opposite to a main surface in contact with the protective layer 10 .

[0073] In the electromagnetic shielding film 1 , the projections and depressions 11 are formed on the first main surface 10 a of the protective layer 10 , and it is an essential technical feature that the interface expansion area ratio Sdr, which is a parameter of the surface property, is 75.0 to 250%.

[0074] The extended area ratio Sdr of the interface of the first main surface 10 a is preferably 80.0 to 170%, and more preferably 100 to 130%.

[0075] The “expansion area ratio Sdr of the interface” is a numerical value indicating how much the expansion area (surface area) of the definition region increases relative to the area of ​​the definition region.

[0076] When the interface expansion area ratio Sdr of the first main surface 10a is 75.0 to 250%, the distance from the bottom to the top of the concavo-convex 11 of the first main surface 10a and the density of the concavo-convex 11 are in appropriate ranges. Therefore, the first main surface 10a of the protective layer 10 has high hiding power and scratch resistance.

[0077] When the expansion area ratio Sdr of the interface of the first main surface is less than 75.0%, the covering property decreases.

[0078] When the expansion area ratio Sdr of the interface of the first main surface exceeds 250%, the scratch resistance decreases.

[0079] In this specification, the surface properties of the first main surface of the protective layer (Sdr described above, Sdq, Sal, Sa, etc. described below) are values ​​measured based on ISO 25178-6:2010, and the specific measurement method is described in the Examples.

[0080] In the electromagnetic shielding film 1 , the root mean square slope Sdq of the first main surface 10 a of the protective layer 10 is preferably 1.50 to 2.70, more preferably 1.80 to 2.30, and further preferably 1.90 to 2.10.

[0081] The “root mean square slope Sdq” is a parameter calculated from the root mean square of the slopes at all points in the definition area.

[0082] When the RMS slope Sdq of the first main surface 10a is 1.50 to 2.70, the distance from the bottom to the top of the asperities 11 of the first main surface 10a and the density of the asperities 11 are in appropriate ranges. Therefore, the hiding power and scratch resistance of the first main surface of the protective layer are improved.

[0083] When the root mean square slope Sdq of the first main surface is less than 1.50, the hiding power decreases.

[0084] When the root mean square slope Sdq of the first main surface exceeds 2.70, the scratch resistance decreases.

[0085] In the electromagnetic shielding film 1 , the minimum autocorrelation length Sal of the first main surface 10 a of the protective layer 10 is preferably 2.5 to 10.0 μm, more preferably 2.5 to 6.0 μm, and further preferably 2.5 to 4.5 μm.

[0086] "Minimum autocorrelation length Sal" indicates the horizontal distance in the direction where the autocorrelation function decays fastest toward a specific value s (default is 0.2). In addition, "Minimum autocorrelation length Sal" numerically expresses the density of the concave and convex shapes in units of length, so the smaller the value, the finer the pores.

[0087] When the minimum autocorrelation length Sal of the first main surface 10a of the protective layer 10 is 2.5 to 10.0 μm, the roughness of the concavities 11 on the first main surface 10a of the protective layer 10 becomes appropriate. Therefore, the first main surface 10a of the protective layer 10 has high hiding power and high scratch resistance.

[0088] In the electromagnetic shielding film 1 , the arithmetic mean height Sa of the first main surface 10 a of the protective layer 10 is preferably 0.3 μm or more and less than 0.8 μm, and more preferably 0.3 to 0.5 μm.

[0089] The "arithmetic mean height Sa" is a numerical value indicating the average value of the heights (absolute value) of the surface having irregularities from the average surface.

[0090] When the arithmetic mean height Sa of the first main surface 10a of the protective layer 10 is greater than or equal to 0.3 μm and less than 0.8 μm, the distance from the bottom to the top of the concavo-convex 11 in the first main surface 10a of the protective layer 10 is short. Generally, when the distance from the bottom to the top of the concavo-convex 11 in the first main surface 10a of the protective layer 10 is short, the covering property of the first main surface 10a of the protective layer 10 is likely to be reduced.

[0091] However, in the electromagnetic shielding film 1 , the extended area ratio Sdr of the interface of the first main surface 10 a is 75.0 to 250%. Therefore, even if the arithmetic mean height Sa is within the above range, the covering property of the first main surface 10 a of the protective layer 10 is sufficiently high.

[0092] In the electromagnetic shielding film 1 , the 60° glossiness of the first main surface 10 a is preferably 5.0 or less, more preferably 2.0 to 4.0.

[0093] In the electromagnetic shielding film 1 , the 85° glossiness of the first main surface 10 a is preferably 60.0 or less, more preferably 30.0 to 50.0.

[0094] In the electromagnetic shielding film 1 , when the 60° glossiness or the 85° glossiness is within the above range, the hiding power of the first main surface 10 a of the protective layer 10 of the electromagnetic shielding film 1 becomes sufficiently high.

[0095] In addition, in this specification, "60° glossiness" and "85° glossiness" are values ​​measured using BYK Gardner Micro-Gloss (portable gloss meter).

[0096] In the electromagnetic shielding film 1, the L* value on the first main surface 10a is preferably 30.0 or less, and more preferably 26.7 to 28.0. In addition, in this specification, the L* value refers to a value measured in accordance with JIS Z 8781-4 (2013).

[0097] Hereinafter, each structure of the electromagnetic shielding film 1 will be described in detail.

[0098] (Protective layer)

[0099] The protective layer 10 is preferably formed of a resin material, has insulating properties, and satisfies predetermined mechanical strength, chemical resistance, and heat resistance.

[0100] The resin material constituting the protective layer 10 is not particularly limited as long as it has sufficient insulating properties, and for example, a thermoplastic resin composition, a thermosetting resin composition, an active energy ray-curable composition, or the like can be used.

[0101] As the thermoplastic resin composition, there is no particular limitation, and styrene resin compositions, vinyl acetate resin compositions, polyester resin compositions, polyethylene resin compositions, polypropylene resin compositions, imide resin compositions, and acrylic resin compositions can be used. As the thermosetting resin composition, there is no particular limitation, and phenolic resin compositions, epoxy resin compositions, urethane resin compositions, melamine resin compositions, and alkyd resin compositions can be used. As the active energy ray-curable composition, there is no particular limitation, and for example, a polymerizable compound having at least two (meth)acryloyloxy groups in the molecule can be used. These compositions can be used alone or in combination of two or more.

[0102] The protective layer 10 may contain a curing accelerator, a tackifier, an antioxidant, a pigment, a dye, a plasticizer, an ultraviolet absorber, a defoamer, a leveling agent, a filler, a flame retardant, a viscosity modifier, an anti-blocking agent, and the like as necessary.

[0103] The protective layer 10 has projections and depressions 11 on the first main surface 10 a .

[0104] The method for forming the concavo-convex 11 is not particularly limited, and the concavo-convex 11 can be formed, for example, by the following method.

[0105] A method of forming a matte layer having projections and depressions on a base film, applying a resin for forming the protective layer 10 on the surface of the matte layer, and drying the resin to transfer the projections and depressions of the matte layer to the protective layer 10 .

[0106] A method in which a resin for forming a protective layer is applied onto the shield layer (metal layer) 20, a mold having projections and depressions is pressed onto the resin, and then the resin is cured to transfer the projections and depressions of the mold to the protective layer.

[0107] A method of adding unevenness-forming particles to the protective layer 10 .

[0108] A method of forming the asperities 11 by performing a sandblasting process on the first main surface 10 a of the protective layer 10 .

[0109] Among the above methods, a preferred method is to form a matte layer having projections and depressions on a substrate film, apply a resin for forming the protective layer 10 on the surface of the matte layer, and dry the resin to transfer the projections and depressions of the matte layer to the protective layer 10 .

[0110] It should be noted that, when the concavoconvex forming particles are added to the protective layer 10 to form the concavoconvex 11, the concavoconvex forming particles can be, for example, resin particles or inorganic particles. Resin particles can use acrylic resin particles, polyacrylonitrile particles, polyurethane particles, polyamide particles and polyimide particles, etc. In addition, inorganic particles can use calcium carbonate particles, calcium silicate particles, clay, kaolin, talc, silica particles, glass particles, diatomaceous earth, mica powder, aluminum oxide particles, magnesium oxide particles, zinc oxide particles, barium sulfate particles, aluminum sulfate particles, calcium sulfate particles and magnesium carbonate particles, etc. These resin particles and inorganic particles can be used alone or in combination. From the viewpoint of improving the scratch resistance of the protective layer, inorganic particles are preferred.

[0111] The thickness of the protective layer 10 is not particularly limited and can be appropriately set as needed, but is preferably 1 to 20 μm, more preferably 4 to 10 μm.

[0112] If the thickness of the protective layer is less than 1 μm, the strength of the protective layer decreases, making it difficult to protect the shielding layer (metal layer).

[0113] When the thickness of the protective layer exceeds 20 μm, the flexibility of the electromagnetic shielding film decreases.

[0114] (Metal layer)

[0115] The material of the metal layer is not particularly limited, and nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, zinc, and alloys containing two or more of these metals may be used.

[0116] The material and thickness of the metal layer may be appropriately selected according to the desired electromagnetic wave shielding effect and repeated bending / sliding resistance.

[0117] For example, from the viewpoint of obtaining a sufficient electromagnetic wave shielding effect, the thickness of the metal layer is preferably 0.1 μm or more.

[0118] In addition, from the viewpoints of productivity, bendability, and the like, the thickness is preferably 8 μm or less.

[0119] The metal layer may be formed by electrolytic plating, chemical plating, sputtering, electron beam evaporation, vacuum evaporation, CVD, organic metal, etc. The metal layer may also be formed of metal foil, metal nanoparticles, scaly metal particles, etc.

[0120] (Conductive adhesive layer)

[0121] In the electromagnetic shielding film 1 , the conductive adhesive layer 30 may have isotropic conductivity or anisotropic conductivity.

[0122] As described later, the conductive adhesive layer 30 is disposed on the printed circuit board. In this case, if the conductive adhesive layer 30 having either isotropic conductivity or anisotropic conductivity is brought into contact with the ground wiring of the printed circuit board, the ground wiring of the printed circuit board can be electrically connected to the shielding layer (metal layer) 20 of the electromagnetic wave shielding film 1 by means of the conductive adhesive layer 30. Thus, the electromagnetic wave shielding film 1 can suitably shield electromagnetic waves.

[0123] When the conductive adhesive layer 30 has anisotropic conductivity, the transmission characteristics of high-frequency signals transmitted in the signal circuit of the printed wiring board are improved compared to the case where the conductive adhesive layer 30 has isotropic conductivity.

[0124] The conductive adhesive layer 30 contains a conductive filler and an adhesive resin.

[0125] The conductive filler of the conductive adhesive layer 30 is not particularly limited, and may be silver powder, copper powder, nickel powder, solder powder, aluminum powder, silver-coated copper powder obtained by silver-plating copper powder, fine particles of polymer fine particles, glass beads, etc. coated with metal, etc.

[0126] Among these, copper powder or silver-coated copper powder, which is available at low cost, is preferred from the viewpoint of economic efficiency.

[0127] The shape of the conductive filler is not particularly limited, and can be appropriately selected from spherical, flake, scale, dendrite, rod, fiber, etc. Among these, flake is preferred.

[0128] If the conductive filler is a flake-shaped conductive filler, when the electromagnetic shielding film 1 is bent, the conductive filler also bends, and it becomes easy to maintain contact between the conductive fillers. As a result, the conductivity of the conductive adhesive layer becomes less likely to decrease.

[0129] The average major diameter of the conductive filler is not particularly limited, but is preferably 0.5 to 15.0 μm, more preferably 5 to 13 μm.

[0130] When the average major axis of the conductive filler is at least 0.5 μm, the conductivity of the conductive adhesive layer will be good.

[0131] When the average major axis of the conductive filler is at most 15.0 μm, the conductive adhesive layer can be made thin.

[0132] In addition, the average major diameter of the conductive filler in this specification means a value measured by the following method.

[0133] A scanning electron microscope (SEM) image of a cross section of the conductive adhesive layer is obtained. The average major axis of the conductive filler is the average value of the major axes of any five conductive fillers in the SEM image.

[0134] The weight ratio of the conductive filler contained in the conductive adhesive layer 30 is preferably 10 to 80 weight %.

[0135] When the conductive adhesive layer 30 has anisotropic conductivity, the weight ratio of the conductive filler contained in the conductive adhesive layer 30 is preferably 10 to 40% by weight, and more preferably 15 to 35% by weight.

[0136] The thickness of the conductive adhesive layer 30 is not particularly limited and may be appropriately set as needed, but is preferably 0.5 to 30.0 μm.

[0137] If the thickness of the conductive adhesive layer is less than 0.5 μm, it becomes difficult to obtain good conductivity.

[0138] When the thickness of the conductive adhesive layer exceeds 30.0 μm, the entire electromagnetic shielding film becomes thick and becomes difficult to handle.

[0139] The material of the adhesive resin contained in the conductive adhesive layer 30 is not particularly limited, and thermoplastic resins such as styrene resins, vinyl acetate resins, polyester resins, polyethylene resins, polypropylene resins, imide resins, amide resins, acrylic resins, and thermosetting resins such as phenolic resins, epoxy resins, urethane resins, melamine resins, and alkyd resins can be used.

[0140] The material of the adhesive resin of the conductive adhesive layer 30 may be one of these alone or a combination of two or more thereof.

[0141] Next, an electromagnetic shielding film according to another aspect of the first embodiment of the present invention will be described.

[0142] Figure 2 This is a cross-sectional view schematically showing an example of a cross section of an electromagnetic shielding film according to another aspect of the first embodiment of the present invention.

[0143] Figure 2 The electromagnetic wave shielding film 101 shown includes: a protective layer 10 having a first main surface 10 a and a second main surface 10 b facing the first main surface 10 a ; and a shielding layer 120 arranged on the second main surface 10 b of the protective layer 10 .

[0144] Furthermore, the shielding layer 120 is formed of a conductive adhesive layer.

[0145] In addition, since the conductive adhesive layer functions as a shielding layer, it is necessary to be an isotropic conductive adhesive layer.

[0146] That is, in the electromagnetic shielding film 101 , the metal layer and the conductive adhesive layer form a shielding layer (conductive adhesive layer) 120 , and the structure is the same as that of the electromagnetic shielding film 1 described above.

[0147] The electromagnetic wave shielding film according to the first embodiment of the present invention may include a base film having a matte layer formed thereon.

[0148] Such a method will be described with reference to the accompanying drawings.

[0149] Figure 3 It is a cross-sectional view schematically showing an example of a cross section of the electromagnetic wave shielding film according to the first embodiment of the present invention, that is, an electromagnetic wave shielding film having a matte layer and a base film.

[0150] Figure 3 In the electromagnetic wave shielding film 1 , a matte layer 40 is further arranged on the first main surface 10 a of the protective layer 10 , and a base film 50 is arranged on the main surface 40 b of the matte layer 40 opposite to the main surface 40 a in contact with the protective layer 10 .

[0151] When manufacturing the electromagnetic wave shielding film 1, the concavo-convex 41 formed on the matte layer 40 is transferred to the first main surface 10a of the protective layer 10, thereby forming the concavo-convex 11 on the first main surface 10a of the protective layer 10. Therefore, by adjusting the concavo-convex 41 of the matte layer 40, the surface properties such as the extended area ratio Sdr of the interface in the first main surface 10a of the protective layer 10 can be made to be the desired properties.

[0152] When the base film 50 is disposed on the electromagnetic shielding film 1, the first main surface 10a of the protective layer 10 can be protected from impact, etc. Therefore, when the electromagnetic shielding film 1 or 101 is transported, the protective layer 10 can be prevented from being scratched.

[0153] In addition, the preferable materials of the matte layer 40 and the base film 50 are described in detail in the method for producing the electromagnetic shielding film according to the first embodiment of the present invention described later.

[0154] Furthermore, the electromagnetic wave shielding film 101 may include a base film having a matte layer formed thereon.

[0155] Next, applications of the electromagnetic shielding film according to the first embodiment of the present invention will be described.

[0156] The electromagnetic shielding film according to the first embodiment of the present invention is bonded to a printed wiring board.

[0157] A method for attaching an electromagnetic shielding film according to a first embodiment of the present invention and a shielded printed circuit board having the electromagnetic shielding film attached thereto according to the first embodiment of the present invention will be described below with reference to the drawings.

[0158] Figure 4A This is a cross-sectional view schematically showing an example of a state in which the electromagnetic shielding film according to the first embodiment of the present invention is attached to a printed circuit board.

[0159] Figure 4B This is a cross-sectional view schematically showing an example of a cross section of a shield printed circuit board using the electromagnetic shield film according to the first embodiment of the present invention.

[0160] like Figure 4A As shown, the electromagnetic shielding film 1 including the base film 50 on which the matte layer 40 is formed is attached so that the conductive adhesive layer 30 is in contact with the printed circuit board 60 .

[0161] The printed circuit board 60 is formed of a base film 61, a printed circuit 62 including a ground circuit 62a disposed on the base film 61, and a cover layer 63 covering the printed circuit 62. The cover layer 63 has an opening 63a that exposes the ground circuit 62a.

[0162] When the electromagnetic shielding film 1 is attached to the printed circuit board 60 , the conductive adhesive layer 30 of the electromagnetic shielding film 1 fills the opening 63 a of the cover layer 63 so as to be in contact with the ground circuit 62 a .

[0163] In this way, the ground circuit 62a of the printed circuit board 60 is electrically connected to the conductive adhesive layer 30 and the shielding layer (metal layer) 20 of the electromagnetic shielding film 1. Thus, the electromagnetic shielding film 1 suitably shields electromagnetic waves.

[0164] In the printed circuit board 60, the base film 61 and the cover layer 63 are preferably both formed of engineering plastics, such as polypropylene, cross-linked polyethylene, polyester, polybenzimidazole, polyimide, polyimide amide, polyetherimide, polyphenylene sulfide (PPS) and the like.

[0165] In the printed circuit board 60 , the printed circuit 62 can be made of a common circuit material such as copper.

[0166] The base film 61 and the printed circuit 62 may be bonded by an adhesive, or may be bonded in the same manner as a so-called adhesive-free copper-clad laminate without using an adhesive. In addition, the cover layer 63 may be formed by bonding a plurality of flexible insulating films by an adhesive, and may be formed by a series of methods such as coating, drying, exposure, development, and heat treatment of a photosensitive insulating resin.

[0167] As a method of attaching the electromagnetic wave shielding film 1 to the printed wiring board 60 , a conventionally known method can be adopted.

[0168] For example, it is preferred that the electromagnetic wave shielding film 1 is arranged on the printed circuit board 60 in such a manner that the conductive adhesive layer 30 of the electromagnetic wave shielding film 1 contacts the covering layer 63 of the printed circuit board 60, and then thermally pressed under the conditions of 150-200°C, 2-5 MPa, and 1-60 minutes.

[0169] Afterwards, if Figure 4B As shown, the base film 50 on which the matte layer 40 is formed is peeled off from the electromagnetic wave shielding film 1 , thereby forming the shielded printed wiring board 70 .

[0170] Next, a method for producing the electromagnetic shielding film 1 will be described.

[0171] The method for producing the electromagnetic wave shielding film 1 includes the following steps: (1) a matte layer forming step, (2) a protective layer forming step, (3) a metal layer forming step, and (4) a conductive adhesive layer forming step.

[0172] Each process is described in detail below.

[0173] (1) Matt layer forming process

[0174] Figure 5 This is a process diagram schematically showing an example of a matte layer forming step in the method for producing the electromagnetic shielding film according to the first embodiment of the present invention.

[0175] When manufacturing the electromagnetic wave shielding film of the present invention, Figure 5 As shown, a base film 50 is prepared. Then, a resin composition containing concavity-convexity-forming particles is applied to the main surface of the base film 50 and dried to form a matte layer 40 having concavities and convexities 41 .

[0176] The material of the substrate film 50 is not particularly limited, and examples thereof include plastic sheets such as polyethylene terephthalate, polyethylene naphthalate, polyvinyl fluoride, polyvinylidene fluoride, rigid polyvinyl chloride, polyvinylidene chloride, nylon, polyimide, polystyrene, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polycarbonate, polyacrylonitrile, polybutene, soft polyvinyl chloride, polyvinylidene fluoride, polyethylene, polypropylene, polyurethane, ethylene vinyl acetate copolymer, polyvinyl acetate, etc., paper such as cellophane, high-quality paper, kraft paper, coated paper, various nonwoven fabrics, synthetic paper, metal foil, and composite films combining these.

[0177] The concavoconvex forming particles constituting the matt layer 40 are not particularly limited, and resin particles or inorganic particles can be used. Resin particles can use acrylic resin particles, polyacrylonitrile particles, polyurethane particles, polyamide particles, polyimide particles, etc. In addition, inorganic particles can use calcium carbonate particles, calcium silicate particles, clay, kaolin, talc, silicon dioxide particles, glass particles, diatomaceous earth, mica powder, aluminum oxide particles, magnesium oxide particles, zinc oxide particles, barium sulfate particles, aluminum sulfate particles, calcium sulfate particles, magnesium carbonate particles, etc. These resin particles and inorganic particles can be used alone or in combination.

[0178] The resin component constituting the matte layer 40 is not particularly limited, and polyester resin compositions, acrylic resin compositions, phenolic resin compositions, epoxy resin compositions, urethane resin compositions, silicone resin compositions, melamine resin compositions, alkyd resin compositions, etc. can be used.

[0179] The properties of the concavo-convex 41 of the matte layer 40 can be formed into desired properties by adjusting the type, size, and amount of the concavo-convex forming particles used and the type of the resin component.

[0180] (2) Protective layer formation process

[0181] Figure 6 This is a process diagram schematically showing an example of a protective layer forming step in the method for producing the electromagnetic shielding film according to the first embodiment of the present invention.

[0182] Then, if Figure 6 As shown in FIG. 1 , the protective layer 10 is formed on the main surface of the mat layer 40 on which the concavo-convex 41 is formed. Thus, the concavo-convex 41 of the mat layer 40 is transferred to the protective layer 10, and the concavo-convex 11 of the protective layer 10 is formed.

[0183] The protective layer 10 can be formed by a conventionally known method.

[0184] (3) Metal layer formation process

[0185] Figure 7 This is a process diagram schematically showing an example of a metal layer forming step in the method for producing the electromagnetic shielding film according to the first embodiment of the present invention.

[0186] Then, if Figure 7 As shown, a shield layer (metal layer) 20 is formed on the second main surface 10 b of the protective layer 10 .

[0187] The method for forming the metal layer is not particularly limited, and the following methods may be used: a method of laminating a metal foil formed to a predetermined thickness on the protective layer 10; a method of forming the metal layer on the surface of the protective layer 10 by vapor deposition or plating.

[0188] (4) Conductive Adhesive Layer Forming Step

[0189] Figure 8 This is a process diagram schematically showing an example of a conductive adhesive layer forming step in the method for producing the electromagnetic shielding film according to the first embodiment of the present invention.

[0190] Then, if Figure 7 As shown, a conductive adhesive layer 30 is formed on the shielding layer (metal layer) 20 .

[0191] The method for forming the conductive adhesive layer 30 is not particularly limited, and the conductive adhesive layer 30 may be formed by applying a conductive adhesive layer composition containing a material constituting the conductive adhesive layer 30 .

[0192] Examples of coating methods include conventionally known coating methods, such as gravure coating, kiss coating, die coating, lip coating, comma coating, blade coating, roll coating, knife coating, spray coating, rod coating, spin coating, and dip coating.

[0193] Through the above steps, the electromagnetic wave shielding film 1 can be manufactured.

[0194] It should be noted that Figure 8 When the electromagnetic wave shielding film 1 is rotated 180°, it becomes Figure 3The electromagnetic wave shielding film 1 shown has a base film 50 on which a matte layer 40 is formed.

[0195] It should be noted that when manufacturing the above-mentioned electromagnetic wave shielding film 101, the "(3) metal layer forming step" is not carried out, but in the "(4) conductive adhesive layer forming step", a conductive adhesive layer with isotropic conductivity is formed on the second main surface of the protective layer, thereby manufacturing the electromagnetic wave shielding film 101.

[0196] In addition, in the above-mentioned "(1) matt layer forming step", the matt layer 40 is formed by coating the base film 50 with a resin composition containing particles for forming projections and recesses. However, in the case of manufacturing the electromagnetic wave shielding of the first embodiment of the present invention, the base film 50 can be embossed to form a portion of the base film 50 as the matt layer 40, and the base film 50 can be sandblasted to form a portion of the base film 50 as the matt layer 40.

[0197] It should be noted that the properties of the concavo-convex 41 of the matte layer 40 can be controlled by adjusting the conditions of the embossing process and the conditions of the sandblasting process.

[0198] (Second embodiment)

[0199] The essential technical feature of the electromagnetic wave shielding film of the second embodiment of the present invention is that the root mean square slope Sdq of the first main surface is 1.50 to 2.70 instead of the expansion area ratio Sdr of the interface of the first main surface being 75.0 to 250%. Apart from this, it has the same structure as the electromagnetic wave shielding film of the first embodiment of the present invention mentioned above.

[0200] In the electromagnetic shielding film according to the second embodiment of the present invention, the root mean square slope Sdq of the first main surface is more preferably 1.80 to 2.30, and further preferably 1.90 to 2.10.

[0201] In the electromagnetic shielding film according to the second embodiment of the present invention, the expansion area ratio Sdr of the interface of the first main surface is preferably 75.0 to 250%, more preferably 80.0 to 170%, and further preferably 100 to 130%.

[0202] Regarding the points other than the above, the preferred configuration of the electromagnetic shielding film according to the second embodiment of the present invention is the same as the preferred configuration of the electromagnetic shielding film according to the first embodiment of the present invention described above.

[0203] (Other embodiments)

[0204] In the electromagnetic shielding film of the present invention, when the shielding layer is formed of a metal layer, a non-conductive adhesive layer may be disposed on the main surface of the metal layer opposite to the main surface in contact with the protective layer.

[0205] In the electromagnetic wave shielding film of the present invention in this aspect, electromagnetic waves can be sufficiently shielded by the metal layer.

[0206] The material of the non-conductive adhesive layer is not particularly limited, and thermoplastic resins such as styrene resins, vinyl acetate resins, polyester resins, polyethylene resins, polypropylene resins, imide resins, amide resins, acrylic resins, and thermosetting resins such as phenolic resins, epoxy resins, urethane resins, melamine resins, and alkyd resins can be used.

[0207] Example

[0208] Hereinafter, although the Example which demonstrates this invention more concretely is shown, this invention is not limited to these Examples.

[0209] (Example 1) to (Example 11) and (Comparative Example 1) to (Comparative Example 5)

[0210] The following methods for producing electromagnetic shielding films are common to each of the Examples and Comparative Examples except for the "(1) matt layer forming step".

[0211] (1) Matt layer forming process

[0212] A polyethylene terephthalate film was prepared as a base film.

[0213] Next, an epoxy resin containing particles for forming irregularities was applied to the main surface of the polyethylene terephthalate film to a thickness of 4.0 μm, thereby forming a matte layer having irregularities.

[0214] At this time, the type, size and amount of the unevenness forming particles were adjusted so that the surface properties of the first main surface of the protective layer of the electromagnetic shielding film of each example and comparative example produced would have the values ​​shown in Table 1.

[0215] (2) Protective layer formation process

[0216] Next, epoxy resin was applied on the matte layer and heated in an electric oven at 100° C. for 2 minutes to form a protective layer with a thickness of 5 μm. In this way, the concavities and convexities of the matte layer were transferred to the first main surface of the protective layer.

[0217] (3) Metal layer formation process

[0218] Then, a 2 μm copper layer is formed on the protective layer by chemical plating. This copper layer becomes a shielding layer.

[0219] (4) Conductive Adhesive Layer Forming Step

[0220] Next, 100 parts by mass of bisphenol A epoxy resin, 0.1 parts by mass of curing agent (Mitsubishi Chemical, ST14), and 25 parts by mass of dendritic silver-coated copper powder (average particle size 13 μm) were added to toluene so that the solid content was 20% by mass, and stirred and mixed to prepare a conductive adhesive layer composition. The obtained conductive adhesive layer composition was applied to the copper layer to form a conductive adhesive layer with a thickness of 15 μm.

[0221] Through the above steps, the electromagnetic shielding films of the examples and comparative examples were manufactured.

[0222] [Evaluation of electromagnetic wave shielding films]

[0223] A polyimide film with a thickness of 25 μm is prepared as a model of the adhered component, and the electromagnetic wave shielding film of each embodiment and each comparative example is arranged in a manner that the conductive adhesive layer is in contact with the polyimide film. The films are heated and pressurized using a press at 170°C, 3 minutes, and 2.0 MPa, and further heated at 150°C for 1 hour and bonded.

[0224] Thereafter, the base film on which the matte layer was formed was peeled off, and the properties of the first main surface of the protective layer of the electromagnetic shielding film of each example and each comparative example were measured and evaluated as follows.

[0225] [Measurement of surface properties of protective layer]

[0226] After measuring any five locations on the surface of the protective layer of the electromagnetic wave shielding film of each embodiment and each comparative example using a confocal microscope (Lasertec, OPTELICS HYBRID, objective lens 100 times), the surface slope correction was performed using data analysis software (LMeye7), and the surface properties were measured according to ISO 25178-6: 2010. It should be noted that the cutoff wavelength of the S filter was set to 0.0025 mm, and the cutoff wavelength of the L filter was set to 0.8 mm.

[0227] The results are shown in Table 1.

[0228] [Measurement of glossiness]

[0229] The 60° gloss and 85° gloss of the protective layer surface of the electromagnetic wave shielding film of each Example and each Comparative Example were measured using BYK Gardner Micro-Gloss (portable gloss meter).

[0230] [Determination of L* value]

[0231] The L* value of the protective layer surface of the electromagnetic shielding film of each Example and each Comparative Example was measured using an integrating sphere spectrophotometer (X-Rite, Ci64, tungsten light source). It should be noted that the a* value and b* value were also measured.

[0232] [Evaluation of scratch resistance]

[0233] The protective layer of the electromagnetic wave shielding film of each embodiment and each comparative example was scratched with a fingernail at a load of 0.5 to 0.8 N. Afterwards, the protective layer of the electromagnetic wave shielding film of each embodiment and each comparative example was visually inspected, and the scratch resistance was evaluated with a score of 1 to 6. It should be noted that in this evaluation, the higher the score, the higher the scratch resistance. The evaluation results are shown in Table 1.

[0234] For the benchmark of scoring, such as Figures 9A to 9F shown.

[0235] Fig.9A This is a photograph showing the state of the surface of the protective layer of the electromagnetic shielding film which serves as a reference for score 6 in the evaluation of scratch resistance.

[0236] Fig. 9B This is a photograph showing the state of the surface of the protective layer of the electromagnetic shielding film which serves as a reference for score 5 in the evaluation of scratch resistance.

[0237] Fig. 9C This is a photograph showing the state of the surface of the protective layer of the electromagnetic shielding film which serves as a reference for score 4 in the evaluation of scratch resistance.

[0238] Fig.9D This is a photograph showing the state of the surface of the protective layer of the electromagnetic shielding film which serves as a reference for score 3 in the evaluation of scratch resistance.

[0239] Fig.9E This is a photograph showing the state of the surface of the protective layer of the electromagnetic shielding film which serves as a basis for score 2 in the evaluation of scratch resistance.

[0240] Fig.9F This is a photograph showing the state of the surface of the protective layer of the electromagnetic shielding film which serves as a reference for score 1 in the evaluation of scratch resistance.

[0241] [Evaluation of covering property]

[0242] The first main surface of the protective layer of the electromagnetic shielding film of each example and each comparative example was visually inspected to determine the hiding power.

[0243] Specifically, a printed circuit board having a base layer, a circuit pattern formed by a copper foil (line width of 0.1 mm and height of 12 μm) arranged on the base layer, and a polyimide film (thickness of 12.5 μm) bonded to the base layer with an adhesive layer (thickness of 25 μm) in a manner covering the circuit pattern is bonded to an electromagnetic wave shielding film using a press machine at a temperature of 170°C, a time of 3 minutes, and a pressure of 2 to 3 MPa to produce a shielded wiring substrate. The shielded wiring substrate is placed on a flat table, and in an environment where the illumination on the surface of the shielded wiring substrate is 800 to 1000 lux, it is evaluated whether the circuit pattern can be seen from the electromagnetic wave shielding film side. The viewing angle is set to a range of 0 to 180° relative to the electromagnetic wave shielding film surface.

[0244] Table 1 shows the results.

[0245] It should be noted that the determination criteria are as follows.

[0246] Fig. 10A This is a photograph of the first main surface of the protective layer, which serves as a criterion for "excellent (⊚)" in judging the hiding power of the first main surface of the protective layer of the electromagnetic wave shielding film.

[0247] Fig. 10B This is a photograph of the surface of the protective layer which serves as a standard for "good (0)" in judging the hiding power of the first main surface in the protective layer of the electromagnetic wave shielding film.

[0248] Fig. 10C This is a photograph of the first main surface of the protective layer, which serves as a criterion for "acceptable (△)" in judging the hiding power of the first main surface of the protective layer of the electromagnetic shielding film.

[0249] Excellent (◎): Fig. 10A As shown, the gloss of the first main surface of the protective layer is sufficiently suppressed to give a matte feeling, and the circuit pattern of the printed wiring board cannot be discerned.

[0250] Good (○): Fig. 10B As shown, the gloss of the first main surface of the protective layer is suppressed to a certain extent, and the circuit pattern of the printed wiring board is almost indistinguishable.

[0251] Yes (△): If Fig. 10C As shown, the gloss of the first main surface of the protective layer was not suppressed, and it was difficult to say that it had a matte feel, and the circuit pattern of the printed wiring board could be recognized.

[0252] [Table 1]

[0253]

[0254] As shown in Table 1, when the interface expansion area ratio Sdr of the first main surface of the protective layer of the electromagnetic shielding film was 75.0 to 250% and the root mean square slope Sdq was 1.50 to 2.70, both hiding power and scratch resistance were judged to be high.

[0255] In addition, when the interface expansion area ratio Sdr is less than 75.0%, or when the root mean square slope Sdq is less than 1.50, it is judged that the hiding power is low.

[0256] In addition, when the interface expansion area ratio Sdr exceeds 250%, or when the root mean square slope Sdq exceeds 2.70, it is determined that the scratch resistance is low.

[0257] The following matters are described in this manual.

[0258] The present disclosure (1) is an electromagnetic wave shielding film, characterized in that it comprises: a protective layer having a first main surface and a second main surface opposite to the above-mentioned first main surface; and a shielding layer arranged on the second main surface of the above-mentioned protective layer, and the expansion area ratio Sdr of the interface of the above-mentioned first main surface is 75.0~250%.

[0259] The present disclosure (2) is an electromagnetic wave shielding film, characterized in that it comprises: a protective layer having a first main surface and a second main surface opposite to the first main surface; and a shielding layer arranged on the second main surface of the protective layer, wherein the root mean square slope Sdq of the first main surface is 1.50 to 2.70.

[0260] The present disclosure (3) is the electromagnetic shielding film according to the present disclosure (1) or (2), wherein the minimum autocorrelation length Sal of the first main surface is 2.5 to 10.0 μm.

[0261] The present disclosure (4) is the electromagnetic shielding film according to any one of the present disclosures (1) to (3), wherein an arithmetic mean height Sa of the first main surface is 0.3 μm or more and less than 0.8 μm.

[0262] The present disclosure (5) is the electromagnetic shielding film according to any one of the present disclosures (1) to (4), wherein the 60° glossiness of the first main surface is 5.0 or less.

[0263] The present disclosure (6) is the electromagnetic shielding film according to any one of the present disclosures (1) to (5), wherein the 85° glossiness of the first main surface is 60.0 or less.

[0264] The present disclosure (7) is an electromagnetic wave shielding film as described in any one of the present disclosures (1) to (6), wherein the shielding layer is formed by a metal layer, and a conductive adhesive layer is arranged on the main surface of the metal layer opposite to the main surface in contact with the protective layer.

[0265] The present disclosure (8) is the electromagnetic shielding film according to any one of the present disclosures (1) to (6), wherein the shielding layer is formed of a conductive adhesive layer.

[0266] The present disclosure (9) is an electromagnetic wave shielding film described in any one of the present disclosures (1) to (8), wherein an extinction layer is also arranged on the above-mentioned first main surface of the above-mentioned protective layer, and a substrate film is arranged on the main surface of the above-mentioned extinction layer which is opposite to the main surface in contact with the above-mentioned protective layer.

[0267] Description of Reference Numerals

[0268] 1. 101 Electromagnetic wave shielding film

[0269] 10. Protective layer

[0270] 10a First main surface of protective layer

[0271] 10b Second main surface of protective layer

[0272] 11. Concave and convex of protective layer

[0273] 20, 120 shielding layer

[0274] 30 Conductive adhesive layer

[0275] 40 Matt layer

[0276] 40a, 40b Main surface of matte layer

[0277] 41 Concavoconvexity of matte layer

[0278] 50 Base film

[0279] 60 Printed Circuit Board

[0280] 61 Basic film

[0281] 62 Printed Circuit

[0282] 62a Grounding circuit

[0283] 63 Overlay

[0284] 63a Opening

[0285] 70 Shielded printed circuit board.

Claims

1. An electromagnetic wave shielding film, characterized in that: have: a protective layer having a first main surface and a second main surface opposite to the first main surface; and, a shielding layer disposed on the second main surface of the protective layer, The expansion area ratio Sdr of the interface of the first main surface is 75.0 to 250%.

2. An electromagnetic wave shielding film, characterized in that: have: a protective layer having a first main surface and a second main surface opposite to the first main surface; and, a shielding layer disposed on the second main surface of the protective layer, The root mean square slope Sdq of the first main surface is 1.50 to 2.

70.

3. The electromagnetic wave shielding film according to claim 1 or 2, wherein: The minimum autocorrelation length Sal of the first main surface is 2.5 to 10.0 μm.

4. The electromagnetic shielding film according to any one of claims 1 to 3, wherein An arithmetic mean height Sa of the first main surface is greater than or equal to 0.3 μm and less than 0.8 μm.

5. The electromagnetic wave shielding film according to any one of claims 1 to 4, wherein The 60° glossiness of the first main surface is 5.0 or less.

6. The electromagnetic shielding film according to any one of claims 1 to 5, wherein The 85° glossiness of the first main surface is 60.0 or less.

7. The electromagnetic shielding film according to any one of claims 1 to 6, wherein The shielding layer is formed by a metal layer, A conductive adhesive layer is disposed on a main surface of the metal layer opposite to a main surface in contact with the protective layer.

8. The electromagnetic wave shielding film according to any one of claims 1 to 6, wherein The shielding layer is formed of a conductive adhesive layer.

9. The electromagnetic wave shielding film according to any one of claims 1 to 8, wherein A matte layer is further disposed on the first main surface of the protective layer, and a base film is disposed on a main surface of the matte layer opposite to a main surface in contact with the protective layer.

Images