Electromagnetic wave shielding film

Abstract

Provided is an electromagnetic wave shielding film having excellent long-term bending resistance. This electromagnetic wave shielding film is provided with a protective layer, a conductive adhesive layer, and a metal vapor deposition layer provided between the protective layer and the conductive adhesive layer, and is characterized in that the electromagnetic wave shielding film has a tensile modulus of 2.1-4.0 GPa (inclusive) and an elongation at break of less than 3.0%.

Description

Technical Field

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

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

[0003] For example, an electromagnetic wave shielding film has a structure composed of a conductive adhesive layer, a shielding layer composed of a metal film, etc., and an insulating layer laminated in this order. By heat pressing the electromagnetic wave shielding film while it is superimposed on a printed wiring board, the electromagnetic wave shielding film is bonded to the printed wiring board via the adhesive layer, thereby producing a shielded printed wiring board. After this bonding, components are mounted on the shielded printed wiring board by reflow soldering. Furthermore, the printed wiring board has a structure in which the printed pattern on the base film is covered by the insulating film.

[0004] Electromagnetic wave shielding films are sometimes used in flexible printed wiring boards. However, since flexible printed wiring boards are repeatedly bent during use, the electromagnetic wave shielding films and their shielding layers used in such flexible printed wiring boards are also repeatedly bent. As a result, the conductive paths of the conductive adhesive layer are disrupted, potentially degrading connection reliability. Furthermore, the shielding layer may be damaged, reducing electromagnetic wave shielding properties.

[0005] In order to solve such a problem, Patent Documents 1 and 2 describe evaluating the resistance value and resistance value change rate of an electromagnetic shielding film when a specific number of bending operations are performed.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent No. 6202767

[0009] Patent Document 2: Japanese Patent No. 5854248 Summary of the Invention

[0010] Problems to be solved by the invention

[0011] However, Patent Documents 1 and 2 do not evaluate the resistance change process, such as measuring the resistance value at each bending. Therefore, it is unclear whether the resistance increase can be suppressed throughout the entire use period of the electromagnetic wave shielding film, given the long service life and frequent bending operations. For example, even if the resistance increase is suppressed during periods of low bending, the resistance value may rise sharply during periods of increased bending.

[0012] 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 excellent long-term folding resistance.

[0013] Solutions for solving problems

[0014] That is, the electromagnetic wave shielding film of the present invention is characterized in that it has a protective layer, a conductive adhesive layer, and a metal vapor-deposited layer arranged between the above-mentioned protective layer and the above-mentioned conductive adhesive layer, and the tensile modulus of the electromagnetic wave shielding film is greater than 2.1 GPa and less than 4.0 GPa, and the elongation at break is less than 3.0%.

[0015] The electromagnetic wave shielding film of the present invention has a tensile modulus of 2.1 GPa to 4.0 GPa and an elongation at break of less than 3.0%. Therefore, a relatively hard and difficult-to-elongate conductive adhesive layer can be used as the conductive adhesive layer. Consequently, the metal vapor-deposited layer on the conductive adhesive layer is less likely to elongate and break during bending. As a result, long-term flex resistance can be improved.

[0016] When the elongation at break is 3.0% or more, the metal vapor-deposited layer on the conductive adhesive layer is easily stretched and broken during bending, and thus high bending resistance cannot be achieved over a long period of time.

[0017] When the tensile modulus is outside the above range, even if the elongation at break is within the above range, high bending resistance may not be obtained for a long period of time.

[0018] It should be noted that in the electromagnetic wave shielding film of the present invention, the metal vapor-deposited layer functions as a shielding layer. For example, if the metal vapor-deposited layer is damaged, the electromagnetic wave shielding properties will be reduced. However, as described above, in the electromagnetic wave shielding film of the present invention, the metal vapor-deposited layer is not easily elongated or damaged. Therefore, the electromagnetic wave shielding film of the present invention can maintain its electromagnetic wave shielding properties for a long time.

[0019] In the electromagnetic wave shielding film of the present invention, it is preferred that the conductive adhesive layer contains a binder component and metal particles, and the binder component contains a urethane-modified polyester resin and an epoxy resin.

[0020] A conductive adhesive layer containing a urethane-modified polyester resin and an epoxy resin as binder components is suitable as the conductive adhesive layer of the electromagnetic wave shielding film having the above-mentioned tensile modulus and the above-mentioned elongation at break.

[0021] Effects of the Invention

[0022] According to the present invention, an electromagnetic wave shielding film having excellent long-term folding resistance can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a cross-sectional view schematically showing an example of the electromagnetic shielding film of the present invention.

[0024] Figure 2 This is a cross-sectional view schematically showing an example of a shield printed wiring board using the electromagnetic shielding film of the present invention.

[0025] Figure 3 This is a graph showing the resistance value change rate (average) of each Example and Comparative Example in the evaluation test of the bending resistance. DETAILED DESCRIPTION

[0026] 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 appropriately modified and applied within the scope of the present invention.

[0027] Figure 1 This is a cross-sectional view schematically showing an example of the electromagnetic shielding film of the present invention.

[0028] Figure 1 The electromagnetic wave shielding film 10 shown includes a protective layer 40 , a conductive adhesive layer 20 , and a metal vapor-deposited layer 30 provided between the protective layer 40 and the conductive adhesive layer 20 .

[0029] The electromagnetic shielding film 10 has a tensile modulus of 2.1 GPa to 4.0 GPa, and a breaking elongation of less than 3.0%.

[0030] Because the electromagnetic wave shielding film 10 has these characteristics, a relatively hard and relatively non-stretchable conductive adhesive layer 20 can be used. Therefore, during bending, the metal vapor-deposited layer 30 on the conductive adhesive layer 20 is less likely to stretch and break. As a result, the long-term (overall) bending resistance can be improved.

[0031] When the breaking elongation of the electromagnetic shielding film 10 is 3.0% or more, the metal vapor-deposited layer 30 on the conductive adhesive layer 20 is easily stretched and broken during bending, thus failing to achieve high bending resistance over a long period of time.

[0032] The breaking elongation of the electromagnetic shielding film 10 is preferably 0.5% or more and less than 3.0%, more preferably 0.6% or more and 2.5% or less, further preferably 0.6% or more and less than 0.7%, or 0.7% or more and 2.0% or less.

[0033] If the tensile modulus of the electromagnetic shielding film 10 is less than 2.1 GPa or greater than 4.0 GPa, even if the elongation at break is less than 3.0%, high bending resistance may not be obtained for a long period of time.

[0034] The tensile modulus of the electromagnetic shielding film 10 is preferably 2.2 GPa or more and 4.0 GPa or less, more preferably 2.3 GPa or more and 3.9 GPa or less, and even more preferably 2.4 GPa or more and 3.8 GPa or less.

[0035] It should be noted that the tensile modulus and elongation at break of the electromagnetic shielding film herein refer to the tensile modulus and elongation at break in the direction perpendicular to the lamination direction of the electromagnetic shielding film, respectively. Furthermore, the tensile modulus and elongation at break of the electromagnetic shielding film can be measured by the methods described in the Examples.

[0036] In the electromagnetic wave shielding film 10 , the conductive adhesive layer 20 contains a resin as a binder component and a conductive filler.

[0037] The conductive adhesive layer 20 may contain more than 39% by weight of a conductive filler. This can impart isotropic conductivity to the conductive adhesive layer 20. To impart isotropic conductivity to the conductive adhesive layer 20, the conductive filler content is preferably 40% to 90% by weight, and more preferably 50% to 80% by weight.

[0038] The conductive adhesive layer 20 may contain 3% to 39% by weight of a conductive filler. This can impart anisotropic conductivity to the conductive adhesive layer 20. To impart anisotropic conductivity to the conductive adhesive layer 20, the conductive filler content is preferably 3% to 35% by weight, and even more preferably 3% to 30% by weight.

[0039] When the proportion of the conductive filler is less than 3% by weight, conductivity is not exhibited.

[0040] Thus, the conductive adhesive layer 20 may have isotropic conductivity ensuring conductivity in all three-dimensional directions consisting of thickness, width, and length, or anisotropic conductivity ensuring conductivity only in the thickness direction.

[0041] In the electromagnetic wave shielding film 10, the particle size (D 50 ) is preferably 3.0 μm or more and 15 μm or less, more preferably 5.0 μm or more and 11 μm or less, and further preferably 5.0 μm or more and 8.0 μm or less.

[0042] Particle size of conductive filler (D 50 ) is less than 3.0 μm, the conductive adhesive layer 20 is thicker than the conductive filler, and the conductive filler cannot come into contact with the ground circuit, so that conductivity may not be obtained.

[0043] Particle size of conductive filler (D 50 ) exceeds 15 μm, the conductive filler may penetrate the protective layer 40 (potentially resulting in poor appearance).

[0044] In the electromagnetic shielding film 10 , the conductive filler is not particularly limited, and may be metal particles (metal fine particles), carbon nanotubes, carbon fibers, metal fibers, or the like.

[0045] When the conductive filler is metal particles, the metal particles are 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, particles obtained by coating polymer particles, glass beads, etc. with metal, etc.

[0046] Among them, from the viewpoint of economic efficiency, copper powder or silver-coated copper powder, which are available at low cost, is preferred.

[0047] The shape of the conductive filler is not particularly limited, and may be appropriately selected from spherical, flat, flaky, dendritic, rod-like, fibrous, and the like.

[0048] In the electromagnetic shielding film 10 , the thickness of the conductive adhesive layer 20 is preferably 5 μm to 50 μm, more preferably 5 μm to 30 μm.

[0049] When the thickness of the conductive adhesive layer is less than 5 μm, the adhesiveness is reduced due to the thinness.

[0050] When the thickness of the conductive adhesive layer exceeds 50 μm, the conductive adhesive layer becomes thick, making it difficult to reduce the size of the electromagnetic wave shielding film.

[0051] In the electromagnetic wave shielding film 10, the material of the binder component (resin) of the conductive adhesive layer 20 is not particularly limited, and thermoplastic resin compositions such as styrene resin compositions, vinyl acetate resin compositions, polyester resin compositions, polyethylene resin compositions, polypropylene resin compositions, imide resin compositions, amide resin compositions, and acrylic resin compositions, and thermosetting resin compositions such as phenolic resin compositions, epoxy resin compositions, urethane resin compositions, melamine resin compositions, and alkyd resin compositions can be used.

[0052] The resin material may be a single type or a combination of two or more types.

[0053] Among them, urethane-modified polyester resin and epoxy resin are preferably included as the adhesive component of the conductive adhesive layer 20. By using the conductive adhesive layer 20 containing such an adhesive component, the tensile modulus and elongation at break of the electromagnetic wave shielding film 10 can be easily set within the above ranges.

[0054] In the electromagnetic wave shielding film 10, the conductive adhesive layer 20 may contain, in addition to the binder component and the conductive filler, a curing accelerator, a thickener, an antioxidant, a pigment, a dye, a plasticizer, an ultraviolet absorber, a defoaming agent, a leveling agent, a filler, a flame retardant, a flame retardant aid, a viscosity regulator, etc. as needed.

[0055] In the electromagnetic wave shielding film 10 , the metal vapor-deposited layer 30 functions as a shielding layer.

[0056] The metal deposition layer 30 preferably contains at least one metal selected from the group consisting of copper, silver, gold, aluminum, nickel, tin, palladium, chromium, titanium, and zinc. Alternatively, the metal deposition layer 30 may be composed of at least two alloys selected from this group.

[0057] The metal vapor-deposited layer 30 composed of these metals can appropriately shield electromagnetic waves.

[0058] Furthermore, as described above, in the electromagnetic shielding film 10 , the metal vapor-deposited layer 30 is not easily stretched and is not easily broken. Therefore, the electromagnetic shielding film 10 can maintain the electromagnetic shielding property for a long period of time.

[0059] In the electromagnetic wave shielding film 10 , the thickness of the metal vapor-deposited layer 30 is preferably 0.1 to 10 μm, more preferably 0.12 to 6 μm, and even more preferably 0.13 to 0.2 μm or 0.25 to 0.4 μm.

[0060] If the shielding layer is less than 0.1 μm thick, it is too thin, resulting in reduced strength. Consequently, bending resistance may be reduced. Furthermore, it is difficult to fully reflect and absorb electromagnetic waves, which can lead to a decrease in electromagnetic shielding properties.

[0061] When the thickness of the shielding layer exceeds 10 μm, the entire electromagnetic shielding film becomes thick and becomes difficult to handle.

[0062] In the electromagnetic wave shielding film 10 , the protective layer 40 has sufficient insulation properties and is not particularly limited as long as it can protect the metal vapor-deposited layer 30 and the conductive adhesive layer 20 . For example, it is preferably composed of a thermoplastic resin composition, a thermosetting resin composition, an active energy ray-curable composition, etc.

[0063] The thermoplastic resin composition is not particularly limited, and examples thereof include styrene resin compositions, vinyl acetate resin compositions, polyester resin compositions, polyethylene resin compositions, polypropylene resin compositions, imide resin compositions, and acrylic resin compositions.

[0064] The thermosetting resin composition is not particularly limited, and examples thereof include phenolic resin compositions, epoxy resin compositions, urethane resin compositions, melamine resin compositions, and alkyd resin compositions.

[0065] The active energy ray-curable composition is not particularly limited, and examples thereof include polymerizable compounds having at least two (meth)acryloyloxy groups in the molecule.

[0066] The protective layer 40 may be composed of a single material or may be composed of two or more materials.

[0067] The protective layer 40 may be a laminate of two or more layers having different physical properties, such as material, hardness, or elastic modulus. For example, if the laminate comprises an outer layer with a lower hardness and an inner layer with a higher hardness, the outer layer provides a cushioning effect, thereby mitigating the pressure applied to the metal-deposited layer 30 during the process of heating and pressing the electromagnetic wave shielding film 10 against the printed wiring board. This prevents the metal-deposited layer 30 from being damaged by steps provided on the printed wiring board.

[0068] The protective layer 40 may contain a curing accelerator, a tackifier, an antioxidant, a pigment, a dye, a plasticizer, an ultraviolet absorber, a defoaming agent, a leveling agent, a filler, a flame retardant, a flame retardant auxiliary, a viscosity modifier, an anti-blocking agent, and the like as needed.

[0069] The pigment is not particularly limited, and examples thereof include black pigments such as carbon black.

[0070] The thickness of the protective layer 40 is not particularly limited and may be appropriately set as needed, but is preferably 1 μm to 15 μm, and more preferably 3 μm to 10 μm.

[0071] When the thickness of the protective layer 40 is less than 1 μm, it is too thin to sufficiently protect the metal vapor-deposited layer 30 and the conductive adhesive layer 20 .

[0072] When the thickness of the protective layer 40 exceeds 15 μm, the electromagnetic shielding film 10 becomes difficult to bend due to excessive thickness, and the toughness of the protective layer 40 decreases, making it difficult to apply the protective layer 40 to parts requiring bending resistance.

[0073] The electromagnetic wave shielding film 10 can be formed, for example, as follows. First, a protective layer composition is applied to a support substrate, followed by heat drying to remove the solvent, thereby forming a protective layer 40. The support substrate can be, for example, a film. The support substrate is not particularly limited and can be formed, for example, from a polyolefin-based, polyester-based, polyimide-based, or polyphenylene sulfide-based material. A release agent layer can be provided between the support substrate and the protective layer composition.

[0074] The protective layer composition can be prepared by adding an appropriate amount of solvent and other compounding agents to the resin composition for the protective layer. Examples of the solvent include toluene, acetone, methyl ethyl ketone, methanol, ethanol, propanol, and dimethylformamide. Other compounding agents may include a crosslinking agent, a polymerization catalyst, a curing accelerator, a colorant, and the like. Other compounding agents may be added as needed or not. Methods for coating the protective layer composition on the supporting substrate include conventionally known coating methods, such as lip coating, comma coating, gravure coating, and die coating.

[0075] Next, the metal vapor deposition layer 30 is formed on the protective layer 40 by vapor deposition.

[0076] Next, the conductive adhesive layer composition is applied onto the metal vapor-deposited layer 30 , and then heated and dried to remove the solvent, thereby forming the conductive adhesive layer 20 .

[0077] The conductive adhesive layer composition includes a conductive adhesive and a solvent. Examples of the solvent include toluene, acetone, methyl ethyl ketone, methanol, ethanol, propanol, and dimethylformamide. The ratio of the conductive adhesive in the conductive adhesive layer composition can be appropriately set according to the thickness of the conductive adhesive layer 20. Examples of methods for coating the conductive adhesive layer composition on the metal vapor-deposited layer 30 include conventional coating methods such as gravure coating, kiss coating, die coating, lip coating, comma coating, blade coating, roller coating, knife coating, spray coating, rod coating, spin coating, and dip coating.

[0078] It should be noted that, if necessary, a release substrate (separator) may be attached to the surface of the conductive adhesive layer 20. The release substrate may be a base film made of polyethylene terephthalate, polyethylene naphthalate, or the like, coated with a silicone or non-silicone release agent on the side where the conductive adhesive layer 20 is to be formed. The thickness of the release substrate is not particularly limited and can be determined based on ease of use.

[0079] Next, a shield printed wiring board using the electromagnetic wave shielding film of the present invention will be described.

[0080] Figure 2 This is a cross-sectional view schematically showing an example of a shield printed wiring board using the electromagnetic shielding film of the present invention.

[0081] Figure 2 The shielded printed wiring board 1 shown is composed of a printed wiring board 50 and an electromagnetic wave shielding film 10 .

[0082] The printed wiring board 50 includes a base film 51 , a printed circuit 52 arranged on the base film 51 , and a cover layer 53 arranged so as to cover the printed circuit 52 .

[0083] In the printed wiring board 50 , the printed circuit 52 includes a ground circuit 52 a , and an opening 53 a is formed in the cover layer 53 to expose the ground circuit 52 a .

[0084] In addition, the printed wiring board 50 is desirably a flexible printed wiring board.

[0085] The shield printed wiring board 1 includes the electromagnetic wave shielding film 10, and the electromagnetic wave shielding film 10 has sufficient flexing resistance. Therefore, the shield printed wiring board 1 also has sufficient flexing resistance.

[0086] In the shield printed wiring board 1 , the electromagnetic wave shielding film 10 is arranged on the printed wiring board 50 so that the coverlay 53 is in contact with the conductive adhesive layer 20 .

[0087] In the shielded printed wiring board 1, the conductive adhesive layer 20 fills the opening 53a of the cover layer 53 and contacts the ground circuit 52a. With such a configuration, the shielding characteristics of the electromagnetic wave shielding film 10 can be improved.

[0088] Example

[0089] Examples are shown below to more specifically illustrate the present invention, but the present invention is not limited to these examples.

[0090] (Example 1)

[0091] A predetermined protective layer composition containing an epoxy nylon resin was applied to the surface of a PET film (25 μm thick) as a support substrate and heat-dried using a wire bar to form a first protective layer having a thickness of 2 μm. Subsequently, a predetermined protective layer composition containing a polyester melamine resin was applied to the first protective layer using a wire bar and heat-dried to form a second protective layer having a thickness of 2 μm.

[0092] Next, a silver-deposited film with a thickness of 0.15 μm was formed as a metal-deposited layer on the second protective layer by vacuum evaporation. Next, a predetermined conductive adhesive layer composition was applied to the metal-deposited layer using a wire bar, and then dried at 100°C for 3 minutes to form a conductive adhesive layer with a thickness of 17 μm exhibiting anisotropic conductivity, thereby producing an electromagnetic wave shielding film. The conductive adhesive layer composition used was a composition containing a urethane-modified polyester resin and a bisphenol A-type epoxy resin (46% by weight in total) as binder components, silver-coated copper powder (23% by weight) as a conductive filler, and a flame retardant (31% by weight).

[0093] (Example 2)

[0094] An electromagnetic wave shielding film was produced in the same manner as in Example 1 except that the metal vapor-deposited layer was a silver vapor-deposited film having a thickness of 0.3 μm.

[0095] (Comparative Example 1)

[0096] The thickness of the first protective layer is set to 5 μm, the metal vapor-deposited layer is set to a copper foil with a thickness of 2 μm, and as the composition for the conductive adhesive layer, a composition containing an epoxy nylon resin (85 weight%, including a flame retardant) as a binder component and a silver-coated copper powder (15 weight%) as a conductive filler is used. The thickness of the conductive adhesive layer is set to 15 μm. Except for this, an electromagnetic wave shielding film is prepared in the same manner as in Example 1.

[0097] (Comparative Example 2)

[0098] As the composition for the conductive adhesive layer, a composition comprising an epoxy nylon resin (55 weight%, including a flame retardant) as a binder component, silver-coated copper powder (15 weight%) as a conductive filler, and a flame retardant auxiliary agent (30 weight%) was used. Except for this, an electromagnetic wave shielding film was prepared in the same manner as in Example 1.

[0099] (Comparative Example 3)

[0100] As a composition for the conductive adhesive layer, a composition comprising an epoxy nylon resin (70 weight%, including a flame retardant) as a binder component and silver-coated copper powder (30 weight%) as a conductive filler was used. The thickness of the conductive adhesive layer was set to 8 μm. Except for this, an electromagnetic wave shielding film was prepared in the same manner as in Example 1.

[0101] (Comparative Example 4)

[0102] An electromagnetic shielding film was produced in the same manner as in Example 1 except that the conductive adhesive layer composition used was a composition containing an acrylate resin (90 wt %) as a binder component and silver-coated copper powder (10 wt %) as a conductive filler.

[0103] (Determination of physical properties)

[0104] Dumbbell test pieces (100 mm × 10 mm, 20 mm spacing between markings) were prepared from the resulting electromagnetic shielding films. The tensile modulus, elongation at break, and maximum stress were measured using a tensile testing machine (AGS-X50S, manufactured by Shimadzu Corporation). The measurement conditions were a tensile speed of 50 mm / min and a load cell of 50 N. The tensile modulus was calculated from the slope between stress (2-3 MPa) and elongation at break. For each example and comparative example, multiple samples were prepared, and the elongation at break and tensile modulus were measured for each sample.

[0105] (Evaluation of bending resistance)

[0106] The folding resistance of the obtained electromagnetic wave shielding film was evaluated by the following method.

[0107] Electromagnetic wave shielding films were attached to both sides of a 50 μm thick polyimide film by hot pressing. The films were then cut into test pieces measuring 130 mm x 15 mm in length and width. The folding resistance of the test pieces was evaluated using an MIT folding fatigue tester (Yasuda Seiki Co., Ltd., Model No. 307 MIT folding fatigue tester) according to the method specified in JIS P8115:2001. A resistance meter was connected to the tester to monitor changes in the resistance of the test pieces during the test.

[0108] The test conditions are as follows.

[0109] Bending fixture front R: 1.5mm

[0110] Bending angle: ±135°

[0111] Bending speed: 90 times / minute

[0112] Load: 500gf

[0113] The configurations and physical properties of the Examples and Comparative Examples are summarized in Table 1. In Table 1, the maximum and minimum values ​​of the elongation at break and the tensile modulus among the measured values ​​obtained from a plurality of samples are described.

[0114] [Table 1]

[0115]

[0116] Figure 3 This is a graph showing the resistance value change rate (average) of each example and comparative example in the evaluation test of bending resistance. Figure 3In the graph shown, the average value of the resistance change rate for the measured values ​​with an operation count of 1 to 1000 is set as the point at which the operation count is 0, and the average value of the resistance change rate for the measured values ​​with an operation count of 1001 to 2000 is set as the point at which the operation count is 1000. The average value of the resistance change rate for each 1000 operation count is then plotted similarly. The resistance change rate is calculated using the following formula.

[0117] Resistance change rate = (resistance value at each operation - resistance value at 0 operation) / resistance value at 0 operation × 100

[0118] like Figure 3 As shown, the electromagnetic wave shielding films of each Example, with a tensile modulus of 2.1 GPa to 4.0 GPa and an elongation at break of less than 3.0%, exhibited substantially the same resistance change rate behavior, indicating that the increase in resistance change rate was suppressed over the entire operating cycle. Specifically, in each Example, a resistance change rate of 500% or less was achieved throughout the entire operating cycle, up to 25,000 cycles.

[0119] Description of Reference Numerals

[0120] 1 shielded printed wiring board

[0121] 10Electromagnetic wave shielding film

[0122] 20 conductive adhesive layer

[0123] 30 metal vapor deposition layer

[0124] 40 protection layers

[0125] 50 printed wiring boards

[0126] 51 basement membrane

[0127] 52 printed circuits

[0128] 52a grounding circuit

[0129] 53 covering layer

[0130] 53a opening.

Claims

1. An electromagnetic wave shielding film, characterized in that The invention comprises a protective layer, a conductive adhesive layer, and a metal vapor-deposited layer provided between the protective layer and the conductive adhesive layer. The electromagnetic wave shielding film has a tensile modulus of 2.1 GPa to 4.0 GPa, and an elongation at break of less than 3.0%.

2. The electromagnetic wave shielding film according to claim 1, wherein The conductive adhesive layer contains a binder component and metal particles. The adhesive component comprises urethane-modified polyester resin and epoxy resin.

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