TWI720337B - Electromagnetic wave shielding film - Google Patents

Abstract

The subject of the present invention is to realize an electromagnetic wave shielding film with high bending resistance. The electromagnetic wave shielding film of the present invention includes a conductive adhesive layer and an insulating protective layer for protecting the conductive adhesive layer. The elongation at break of the conductive adhesive layer is 100% or more and 500% or less.

Description

Electromagnetic wave shielding film

The present invention relates to electromagnetic wave shielding films.

2. Description of the Related Art In order to protect electronic circuits from electromagnetic noise, an electromagnetic wave shielding film to be adhered to the surface of a printed wiring board is used. The electromagnetic wave shielding film is made as a laminate in which a conductive adhesive layer and an insulating protective layer are laminated, and a metal foil may be provided between the conductive adhesive layer and the insulating protective layer.

It is known that there is a printed circuit board, which is repeatedly subjected to bending actions like the connecting part of a foldable display and the main body. The electromagnetic wave shielding film used in such a printed wiring board is required to have high resistance to bending.

In order to improve the bending resistance of the electromagnetic wave shielding film, attempts have been made to control the particle size and shape of the conductive filler used in the conductive adhesive layer (for example, refer to Patent Document 1).

Prior Art Documents Patent Documents [Patent Document 1] JP 2011-187895 A

SUMMARY OF THE INVENTION Problems to be Solved by the Invention However, since the bending resistance of the electromagnetic wave shielding film is affected by various factors, even if the particle size and shape of the conductive filler are controlled, the bending resistance may not be sufficiently improved.

The subject of the present invention is to realize an electromagnetic wave shielding film with high bending resistance.

Means for Solving the Problem One aspect of the electromagnetic wave shielding film of the present invention is provided with a conductive adhesive layer and an insulating protective layer, and the breaking elongation of the conductive adhesive layer is 100% or more and 500% or less.

In one aspect of the electromagnetic wave shielding film, the elastic modulus of the conductive adhesive layer can be set to 30 MPa or more and 500 MPa or less.

In one aspect of the electromagnetic wave shielding film, the overall thickness may be 4 μm or more and 20 μm or less.

One aspect of the electromagnetic wave shielding film may further include a shielding layer, which is disposed between the conductive adhesive layer and the insulating protective layer.

One aspect of the shielding wiring board of the present invention includes: a flexible printed wiring board having a grounding circuit; and the electromagnetic wave shielding film of the present invention, which is connected to the grounding circuit by a conductive adhesive layer.

Effects of the Invention According to the electromagnetic wave shielding film of the present invention, the bending resistance can be improved.

The mode for implementing the invention is shown in FIG. 1. The electromagnetic wave shielding film 101 of this embodiment has: a conductive adhesive layer 111, an insulating protective layer 112, and is provided between the conductive adhesive layer 111 and the insulating protective layer 112的Shielding layer 113+. Furthermore, as shown in FIG. 2, the conductive adhesive layer 111 may function as a shielding layer without an independent shielding layer.

In this embodiment, the breaking elongation of the conductive adhesive layer 111 is 100% or more, preferably 200% or more. By increasing the elongation at break of the conductive adhesive layer 111, the resistance to bending (bending resistance) can be improved, and the increase in connection resistance during repeated bending can be suppressed. From the standpoint of improving the bending resistance, the larger the elongation at break, the better, but from the standpoint of resin flow and the filling property of the hole, the elongation at break is 500% or less, preferably 400% or less.

In addition, from the viewpoint of further improving the bending resistance, the elastic modulus of the conductive adhesive layer is preferably 500 MPa or less, more preferably 300 MPa or less. From the standpoint of bending resistance, the smaller the modulus of elasticity is better, but from the standpoint of resin flow and pore filling properties, the modulus of elasticity is preferably 30 MPa or more, more preferably 80 MPa or more.

Furthermore, the stress applied to the shielding layer 113 when the electromagnetic wave shielding film 101 is bent is that the thicker the overall thickness of the electromagnetic wave shielding film 101, the greater the stress. Therefore, from the viewpoint of further improving the bending resistance, the overall thickness of the electromagnetic wave shielding film 101 is preferably 20 μm or less, and more preferably 15 μm or less. Moreover, even in the case where the shielding layer 113 is not provided, the effect of reducing the stress applied to the conductive adhesive layer 111 that functions as a shielding layer can be obtained by reducing the overall thickness. From the viewpoint of bending resistance, the smaller the modulus of elasticity, the better, but due to physical limitations, the overall thickness is preferably 4 μm or more, preferably 6 μm or more. In addition, the thickness of the electromagnetic wave shielding film is a value after pressure which adheres the electromagnetic wave shielding film to a printed wiring board.

In order to make the elongation at break and the modulus of elasticity of the conductive adhesive layer 111 into the above-mentioned values, various methods can be used, and a preferred method is to control the formulation of the conductive adhesive layer 111. The conductive adhesive layer is mainly blended with a resin component such as a thermoplastic resin or a thermosetting resin, and a filler component. The filler components are powder components such as conductive fillers, flame retardants and coloring agents. By adjusting the amount of powder components other than the conductive filler in the filler component, the elongation at break can be controlled. It is particularly preferable not to contain powders having an average particle diameter D50 of 5 μm or more other than the conductive filler.

Regarding the thermoplastic resins that can be used for the conductive adhesive layer 111, examples of the thermoplastic resins include: styrene resins, vinyl acetate resins, polyester resins, polyethylene resins, polypropylene resins, and imine resins. And acrylic resins, etc. One kind of these resins may be used alone, or two or more kinds may be used in combination.

Regarding the thermosetting resin that can be used for the conductive adhesive layer 111, for example, phenol resin, epoxy resin, urethane resin, melamine resin, polyamide resin, and alkyd resin can be used. Wait. The active energy ray curable composition is not particularly limited, but for example, a polymerizable compound having at least two (meth)acryloxy groups in the molecule, etc. may be mentioned. One of these compositions may be used alone, or two or more of them may be used in combination.

The thermosetting resin contains, for example, a first resin component having a reactive first functional group and a second resin component that reacts with the first functional group. The first functional group can be, for example, an epoxy group, an amino group, or a hydroxyl group. The second functional group may be selected based on the first functional group. For example, when the first functional group is an epoxy group, the second functional group may be a hydroxyl group, a carboxyl group, an epoxy group, an amino group, or the like. Specifically, for example, when the first resin component is epoxy resin, the second resin component can be used: epoxy modified polyester resin, epoxy modified polyamide resin, epoxy modified acrylic Resin, epoxy modified polyurethane polyurea resin, carboxy modified polyester resin, carboxy modified polyamide resin, carboxy modified acrylic resin, carboxy modified polyurethane polyurea resin And urethane modified polyester resin, etc. Among these, carboxyl modified polyester resin, carboxyl modified polyamide resin, carboxyl modified polyurethane polyurea resin, and urethane modified polyester resin are preferred. Also, when the first resin component is a hydroxyl group, it can be used as the second resin component: epoxy modified polyester resin, epoxy modified polyamide resin, epoxy modified acrylic resin, epoxy modified Polyurethane polyurea resin, carboxyl modified polyester resin, carboxyl modified polyamide resin, carboxyl modified acrylic resin, carboxyl modified polyurethane polyurea resin and urethane modified Quality polyester resin, etc. Among these, carboxyl modified polyester resin, carboxyl modified polyamide resin, carboxyl modified polyurethane polyurea resin, and urethane modified polyester resin are preferred.

The thermosetting resin may also contain a hardener to promote the thermosetting reaction. When the thermosetting resin has a first functional group and a second functional group, the curing agent can be appropriately selected according to the types of the first functional group and the second functional group. When the first functional group is an epoxy group and the second functional group is a hydroxyl group, an imidazole-based curing agent, a phenol-based curing agent, a cationic curing agent, etc. can be used as the curing agent. These hardeners may be used singly, or two or more of them may be used in combination.

The conductive filler is not particularly limited, and for example, metal fillers, metal-coated resin fillers, carbon fillers, and mixtures thereof can be used. As for the metal filler, copper powder, silver powder, nickel powder, silver-coated copper powder, gold-coated copper powder, silver-coated nickel powder, and gold-coated nickel powder can be cited. These metal powders can be produced by electrolysis, atomization or reduction. Among them, it is preferably any one of silver powder, silver-coated copper powder and copper powder.

From the viewpoint that the fillers are in contact with each other, the average particle size of the conductive filler is preferably 1 μm or more, more preferably 3 μm or more, and preferably 15 m or less, more preferably 20 μm or less. The shape of the conductive filler is not particularly limited, and it may be spherical, flake, dendritic, fibrous, or the like.

The content of the conductive filler can be appropriately selected according to the application, and the total solid content is preferably 5% by mass or more, more preferably 10% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less. From the viewpoint of landfillability, it is preferably 70% by mass or less, and more preferably 60% by mass or less. In addition, when realizing anisotropic conductivity, it is preferably 40% by mass or less, and more preferably 35% by mass or less.

In addition, it can also contain defoamers, antioxidants, viscosity modifiers, thinners, anti-settling agents, leveling agents, coupling agents, coloring agents, and flame retardants within the range that will not affect the elongation at break. Etc. as optional ingredients.

From the viewpoint of reducing the overall thickness of the electromagnetic wave shielding film 101, the thickness of the conductive adhesive layer 111 is preferably 1 μm to 15 μm.

The shielding layer 113 can be formed of metal foil, vapor-deposited film, conductive filler, and the like.

The metal foil is not particularly limited, and it can be made of any one of nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, and zinc, or an alloy containing two or more of them.

The thickness of the metal foil is not particularly limited, but is preferably 0.5 μm or more, more preferably 1.0 μm or more. If the thickness of the metal foil is 0.5 μm or more, the attenuation of the high-frequency signal can be suppressed when the high-frequency signal of 10 MHz to 100 GHz is transmitted to the shielded printed wiring board. In addition, from the viewpoint of reducing the overall thickness of the electromagnetic wave shielding film 101, the thickness of the metal foil is preferably 15 μm or less, more preferably 12 μm or less, and more preferably 9 μm or less. By reducing the thickness of the metal layer, the cost of raw materials can be suppressed and the effect of judging the elongation of the shielding film can be obtained.

The vapor-deposited film is not particularly limited, and it can be formed by vapor-depositing nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, zinc, and the like. Evaporation can use electrolytic plating, electroless plating, sputtering, electron beam evaporation, vacuum evaporation, chemical vapor deposition (CVD), or metal organic chemical vapor deposition (MOCVD).

The vapor-deposited film is not particularly limited, and it can be formed by vapor-depositing nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, zinc, and the like. Evaporation can use electrolytic plating, electroless plating, sputtering, electron beam evaporation, vacuum evaporation, chemical vapor deposition (CVD), or metal organic chemical vapor deposition (MOCVD).

The thickness of the vapor-deposited film is not particularly limited, but is preferably 0.05 μm or more, more preferably 0.1 μm or more. If the thickness of the metal vapor-deposited film is 0.05 μm or more, the electromagnetic wave shielding film 101 has excellent electromagnetic wave shielding characteristics in shielding the printed wiring board. In addition, from the viewpoint of reducing the overall thickness of the electromagnetic wave shielding film 101 and improving the bending resistance, the thickness of the metal vapor-deposited film is preferably less than 0.5 μm, more preferably less than 0.3 μm.

Regarding the conductive filler, the shielding layer 113 can be formed by coating the surface of the insulating protective layer 112 with a solvent containing the conductive filler and then drying it. As the conductive filler, metal fillers, metal-coated resin fillers, carbon fillers, and mixtures thereof can be used. Regarding metal fillers, copper powder, silver powder, nickel powder, silver-coated copper powder, gold-coated copper powder, silver-coated nickel powder, and gold-coated nickel powder can be used. These metal powders can be produced by electrolysis, atomization or reduction. The shape of the metal powder may be spherical, flake, fibrous, dendritic, and the like.

In this embodiment, the thickness of the shielding layer 113 can be appropriately selected according to the required electromagnetic shielding effect and the resistance to repeated bending and sliding. When the shielding layer 113 is a metal foil, from the viewpoint of ensuring the elongation at break The thickness of the shielding layer 113 is preferably set to 12 μm or less.

Furthermore, in the case of a structure in which the conductive adhesive layer 111 functions as a shielding layer, the shielding layer 113 may not be provided.

The insulating protective layer 112 is not particularly limited as long as it has sufficient insulation and can protect the conductive adhesive layer 111 and the shielding layer 113. For example, thermoplastic resin, thermosetting resin, or active energy ray curable resin can be used. form.

The thermoplastic resin is not particularly limited, and styrene resins, vinyl acetate resins, polyester resins, polyethylene resins, polypropylene resins, imine resins, acrylic resins, and the like can be used. The thermosetting resin is not particularly limited, and phenol resins, epoxy resins, urethane resins, melamine resins, polyamide resins, alkyd resins, and the like can be used. The active energy ray-curable resin is not particularly limited. For example, a polymerizable compound having at least two (meth)acryloxy groups in the molecule can be used. The protective layer may be formed of a single material, or may be formed of two or more materials.

The insulating protective layer 112 is not limited to colorants, but may also include hardening accelerators, adhesiveness-imparting agents, antioxidants, plasticizers, ultraviolet absorbers, defoamers, leveling agents, fillers, flame retardants, and viscosity if necessary. One or more of regulators and anti-caking agents.

The insulating protective layer 112 may be a laminate of two or more layers having different physical properties such as material, hardness, or elastic modulus. For example, if it is a laminate of an outer layer with a lower hardness and an inner layer with a higher hardness, the outer layer has a cushioning effect. Therefore, in the step of heating and pressing the electromagnetic wave shielding film 101 on the printed wiring board 102, the application of the electromagnetic wave shielding film 101 to the printed wiring board 102 can be slowed down. The pressure of 113. Therefore, it is possible to prevent the shield layer 113 from being damaged due to the height difference provided on the printed wiring board 102.

From the viewpoint of reducing the overall thickness of the electromagnetic wave shielding film 101, the thickness of the insulating protective layer 112 is preferably 15 μm or less, preferably 10 μm or less, and more preferably 5 μm or less. From the viewpoint of protecting the conductive adhesive layer 111 and the shielding layer 113, it is preferably 1 μm or more, and more preferably 2 μm or more.

The electromagnetic wave shielding film 101 of this embodiment can be formed in the following manner, for example. First, after coating the insulating protective layer composition on a supporting substrate (not shown), it is heated and dried to remove the solvent, and the insulating protective layer 112 is formed. The supporting substrate may be formed in a film shape, for example. The supporting substrate is not particularly limited, and it can be formed of, for example, a polyolefin-based, polyester-based, polyimide-based, polyethylene naphthalate, or polyphenylene sulfide-based material. A release agent layer may also be provided between the supporting substrate and the composition for the protective layer.

The composition for the insulating protective layer can be prepared by adding an appropriate amount of solvent and other compounding agents to the resin composition for the insulating protective layer. The solvent can be, for example, toluene, acetone, methyl ethyl ketone, methanol, ethanol, propanol, and dimethylformamide. Regarding other formulations, crosslinking agents, polymerization catalysts, hardening accelerators, coloring agents, etc. can be added. Other compounding agents can be added as needed, or not added. The method of coating the protective layer composition on the support substrate is not particularly limited, and well-known techniques such as die nozzle coating method, chipped wheel coating method, gravure coating method, or slit die coating method can be used.

Then, if necessary, a shielding layer 113 is formed on the insulating protection layer 112. The method of forming the shielding layer 113 can be appropriately selected according to the type of the shielding layer 113. When the electromagnetic wave shielding film 101 has a structure without the shielding layer 113, this step can be omitted.

Next, after coating the conductive adhesive layer composition on the insulating protective layer 112 or the shielding layer 113, heat drying is performed to remove the solvent, and the conductive adhesive layer 111 is formed.

The conductive adhesive layer composition contains a conductive adhesive and a solvent. The solvent can be, for example, toluene, acetone, methyl ethyl ketone, methanol, ethanol, propanol, and dimethylformamide. The ratio of the conductive adhesive in the composition for the conductive adhesive layer may be appropriately set according to the thickness of the conductive adhesive layer 111 and the like.

The method of coating the conductive adhesive layer composition on the shielding layer 113 is not particularly limited, and the die nozzle coating method, the chipped wheel coating method, the gravure coating method, or the slit die coating method can be used. Wait.

Furthermore, if necessary, a release substrate (separation film) may be attached to the surface of the conductive adhesive layer 111. The peeling substrate can be used to coat silicon-based or non-silicon-based release agents on the surface of the base film on the side where the conductive adhesive layer 111 is formed on the base film such as polyethylene terephthalate and polyethylene naphthalate. Become. In addition, the thickness of the release substrate is not particularly limited, and can be appropriately determined in consideration of ease of use.

As shown in FIG. 3, the electromagnetic wave shielding film 101 of this embodiment can be combined with the printed wiring board 102 to form a shielding wiring board 103. The electromagnetic wave shielding film 101 may also have a shielding layer 113.

The printed wiring board 102 has, for example, a printed circuit, and the printed circuit includes a base member 122 and a ground circuit 125 provided on the base member 122. On the base member 122, an insulating film 121 is adhered via the adhesive layer 123. The insulating film 121 is provided with an opening through which the ground circuit 125 is exposed. The exposed part of the ground circuit 125 may also be provided with a surface layer such as a gold plating layer. In addition, the printed wiring board 102 is not particularly limited, but it can be a flexible board that can be bent.

When the electromagnetic wave shielding film 101 is attached to the printed wiring board 102, the electromagnetic wave shielding film 101 is arranged on the printed wiring board 102 so that the conductive adhesive layer 111 is located on the opening where the ground circuit 125 is exposed. Then, two heating plates (not shown) heated to a predetermined temperature (e.g., 120°C) sandwich the electromagnetic wave shielding film 101 and the printed wiring board 102 from the top and bottom, and apply a predetermined pressure (e.g., 0.5 MPa) Short time (e.g. 5 seconds). Thereby, the electromagnetic wave shielding film 101 is temporarily fixed to the printed wiring board 102.

Then, the temperature of the two hot plates is set to a predetermined temperature (for example, 170° C.) higher than the temperature during the temporary fixation, and pressurized at a predetermined pressure (for example, 3 MPa) for a predetermined time (for example, 30 minutes). Thereby, the electromagnetic wave shielding film 101 can be fixed to the printed wiring board 102. When applying pressure, by fully embedding the conductive adhesive layer 111 in the opening, the strength and conductivity required for the electromagnetic wave shielding film 101 can be achieved.

[Examples] Hereinafter, the electromagnetic wave shielding film of the present invention will be described in further detail using examples. The following examples are examples and are not intended to limit the present invention.

<Production of electromagnetic wave shielding film> A non-silicon-based release agent is applied to the surface of the intended release film to form a release agent layer. Next, the insulating protective layer composition is coated with a wire rod, and heated and dried to form an insulating protective layer. Then, aluminum was vapor-deposited on the insulating protective layer to form a shielding layer with a thickness of 0.15 μm. Then, after coating a predetermined conductive adhesive layer composition on the shielding layer with a wire bar, it was dried at 100° C. for 3 minutes to obtain an electromagnetic wave shielding film.

<Evaluation of bending resistance> The prepared electromagnetic wave shielding film 101 was adhered to the evaluation substrate 201. The next step is to use a press at 170°C for 30 minutes and pressure from 2MPa to 3MPa. The thickness of the subsequent electromagnetic wave shielding film 101 is a value obtained by subtracting the thickness of the evaluation substrate 201 from the thickness of the smooth portion of the evaluation substrate 201 and the electromagnetic wave shielding film subsequent to the evaluation substrate 201. In addition, the thickness was measured in accordance with JIS C 2151 with a micrometer (manufactured by Mitutoyo Co., Ltd., MDH-25), respectively.

As shown in FIG. 4, the evaluation substrate 201 has a base film 211 having a length of 50 mm, a width of 20 mm, and a thickness of 53 μm, and electrodes 212 of 5 mm×8 mm provided at both ends of the base film 211 separated from each other. The electrode 212 is connected to the conductive adhesive layer 111 of the electromagnetic wave shielding film 101.

The resistance value between the test terminals of the evaluation substrate 201 to which the electromagnetic wave shielding film 101 was adhered was measured with a resistance meter (manufactured by Hioki Electric Co., Ltd., RM3544-01), and set as an initial resistance value. Next, the evaluation substrate 201 was bent 180 degrees from the center, and in this state, the resistance value of the evaluation substrate 201 except the electrode 212 was measured by placing a cylindrical weight of 5 cm in diameter and 1 kg on the evaluation substrate 201, and the measured resistance was measured. The value is set to the resistance value when bending. Then, the resistance value that returned to the original state was measured and set as the resistance value at the time of release. The bending and releasing were repeated 20 times, and the rate of change of resistance value R1 during bending and the rate of change of resistance value R2 during releasing were calculated. The rate of change is calculated as (measured value-initial resistance value)/initial resistance value.

<Physical property measurement> The conductive adhesive used to prepare the conductive adhesive layer of the electromagnetic wave shielding film was applied to a release film, and the release film was peeled off to prepare a conductive adhesive layer for a test. A dumbbell test piece (100 mm×10 mm, gauge length 20 mm) was prepared from the conductive adhesive layer for the test, and the elastic modulus, elongation at break, and maximum stress were measured using a tensile testing machine (AGS-X50S, manufactured by Shimadzu Corporation). The measurement conditions are set as tensile speed: 50mm/min, load cell: 50N, and the elastic modulus is calculated from the slope of the stress (2~3MPa) and the elongation at break.

(Example 1) A conductive adhesive containing spherical silver-coated copper powder with an average particle size D50 of 5 μm, which is 43 parts by mass relative to 100 parts by mass of the resin added to a thermosetting resin, was used to form a conductive adhesive with a thickness of 5 μm Then the agent layer. The thickness of the insulating protective layer was set to 5 μm.

The entire thickness of the electromagnetic wave shielding film after being attached to the printed wiring board was 8 μm. The elongation at break of the conductive adhesive layer was 280%, and the elastic modulus of the conductive adhesive layer was 227 MPa. The rate of change R1 of the resistance value at the time of bending when bending was performed 20 times was 26%, and the rate of change of the resistance value at the time of release R2 was 108%.

(Example 2) A conductive adhesive containing 21 parts by mass of dendritic silver-coated copper powder with an average particle size D50 of 13 μm based on 100 parts by mass of the resin added to a thermosetting resin was used to form a conductive adhesive with a thickness of 17 μm性adhesive layer. The thickness of the insulating protective layer was set to 5 μm.

The entire thickness of the electromagnetic wave shielding film after being attached to the printed wiring board was 15 μm. The elongation at break of the conductive adhesive layer was 325%, and the elastic modulus of the conductive adhesive layer was 165 MPa. The rate of change R1 of the resistance value at the time of bending 20 times was 31%, and the rate of change of the resistance value R2 at the time of release was 282%.

(Comparative Example 1) Used to add dendritic silver-coated copper powder with an average particle diameter D50 of 13 μm to a thermosetting resin of 27 parts by mass relative to 100 parts by mass of the resin, and 55 parts by mass relative to 100 parts by mass of the resin A conductive adhesive made of a nitrogen-based flame retardant, forming a conductive adhesive layer with a thickness of 17 μm. The thickness of the insulating protective layer was set to 5 μm.

The entire thickness of the electromagnetic wave shielding film after being attached to the printed wiring board was 15 μm. The elongation at break of the conductive adhesive layer was 24%, and the elastic modulus of the conductive adhesive layer was 748 MPa. The rate of change R1 of the resistance value at the time of bending when bending was performed 20 times was 67%, and the rate of change of the resistance value at the time of release R2 was 632%.

Table 1 shows the results of each Example and Comparative Example. In addition, the resistance value change rate of each Example and Comparative Example is shown in FIG. 5.

[Table 1]

Industrial Applicability The electromagnetic wave shielding film of the present invention has high bending resistance and is particularly suitable as an electromagnetic wave shielding film for flexible printed wiring boards for shielding bending parts.

101‧‧‧Electromagnetic wave shielding film 102‧‧‧Printed wiring board 103‧‧‧Shielding wiring board 111‧‧‧Conductive adhesive layer 112‧‧‧Insulation protection layer 113‧‧‧Shielding layer 115‧‧‧Release film 121 ‧‧‧Insulation film 122‧‧‧Base member 123‧‧‧Adhesive layer 125‧‧‧Earth circuit 201‧‧‧Evaluation substrate 211‧‧‧Base film 212‧‧‧Electrode 213‧‧‧Insulation film

Fig. 1 is a cross-sectional view showing an electromagnetic wave shielding film according to an embodiment. Fig. 2 is a cross-sectional view showing a modification example of the electromagnetic wave shielding film. Fig. 3 is a cross-sectional view of a shielded wiring board using an electromagnetic wave shielding film according to an embodiment. Fig. 4 is a cross-sectional view showing a substrate for evaluating the bending resistance of the electromagnetic wave shielding film. Figure 5 is a graph showing the rate of change of the resistance value in the bending resistance test.

101‧‧‧Electromagnetic wave shielding film

111‧‧‧Conductive adhesive layer

112‧‧‧Insulation protection layer

113‧‧‧Shielding layer

Claims (4)

An electromagnetic wave shielding film, comprising: a conductive adhesive layer; and an insulating protective layer, wherein the conductive adhesive layer contains a conductive filler, and the breaking elongation of the conductive adhesive layer is 100% or more and 500% or less, elastic The modulus is 30 MPa or more and 500 MPa or less. For example, the electromagnetic wave shielding film of claim 1 has an overall thickness of 4 μm or more and 20 μm or less. According to claim 1 or 2, the electromagnetic wave shielding film further includes a shielding layer provided between the conductive adhesive layer and the insulating protective layer. A shielding wiring board comprising: a flexible printed wiring board having a grounding circuit; and the electromagnetic wave shielding film according to any one of claims 1 to 3, which is connected to the grounding circuit by the conductive adhesive layer.

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