WO2023090334A1 - Electromagnetic wave shield film - Google Patents

Electromagnetic wave shield film Download PDF

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Publication number
WO2023090334A1
WO2023090334A1 PCT/JP2022/042463 JP2022042463W WO2023090334A1 WO 2023090334 A1 WO2023090334 A1 WO 2023090334A1 JP 2022042463 W JP2022042463 W JP 2022042463W WO 2023090334 A1 WO2023090334 A1 WO 2023090334A1
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WO
WIPO (PCT)
Prior art keywords
electromagnetic wave
shielding film
wave shielding
filler
protective layer
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PCT/JP2022/042463
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French (fr)
Japanese (ja)
Inventor
慶彦 青柳
憲治 上農
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タツタ電線株式会社
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Publication of WO2023090334A1 publication Critical patent/WO2023090334A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B32B7/025—Electric or magnetic properties
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00—Screening of apparatus or components against electric or magnetic fields

Definitions

  • the present invention relates to an electromagnetic wave shielding film.
  • an electromagnetic wave shielding film has been attached to a printed wiring board such as a flexible printed wiring board (FPC) to shield electromagnetic waves from the outside.
  • a printed wiring board such as a flexible printed wiring board (FPC)
  • Patent Document 1 discloses an electromagnetic wave shielding film comprising a shield layer and an insulating layer laminated on the shield layer, wherein the insulating layer contains silica fine particles, and in the insulating layer describes an electromagnetic wave shielding film characterized in that the content of said silica fine particles is 10 to 50 wt %.
  • a printed wiring board having a high level difference (hereinafter also referred to as a "high level printed wiring board”) is often used for electronic components for vehicles. If a conventional electromagnetic shielding film used for electronic parts such as smartphones is used for such a high-step printed wiring board, the conventional electromagnetic shielding film cannot cope with the high step, and it is difficult to shield electromagnetic waves during manufacturing and use. The film becomes easily damaged. This is believed to be due to the following reasons.
  • a conventional electromagnetic wave shielding film is placed on a printed wiring board by hot pressing. At this time, since high pressure is applied to the electromagnetic wave shielding film at the corners of the steps, there is a problem that the shield layer of the electromagnetic wave shielding film is likely to break. In addition, even if the shield layer is not broken by sticking the electromagnetic wave shielding film to the high step as described above, the electromagnetic wave shielding film may be bent at the corner of the step and cause a large crack in the protective layer. There is In other words, the electromagnetic wave shielding film described in Patent Document 1 has a problem of low adaptability to high steps.
  • the present invention has been made in view of the above problems, and an object of the present invention is to provide an electromagnetic wave shielding film that is less likely to be damaged even when placed on a substrate having a high level difference.
  • the electromagnetic wave shielding film of the present invention comprises a protective layer and an isotropic conductive adhesive layer laminated on the protective layer, the protective layer containing a protective layer filler, and the isotropic conductive adhesive layer contains a resin component, a conductive filler, and a non-conductive filler, and the ratio of the weight of the conductive filler to the weight of the non-conductive filler (weight of conductive filler/weight of non-conductive filler) is , 15.0 to 23.0, and the ratio of the total weight of the conductive filler and the non-conductive filler to the weight of the protective layer filler ((weight of conductive filler + weight of non-conductive filler) / The weight of the protective layer filler) is 1.9 to 2.2.
  • the electromagnetic wave shielding film of the present invention is attached to a printed wiring board. At this time, the electromagnetic wave shielding film of the present invention is arranged so that the isotropic conductive adhesive layer is in contact with the printed wiring board, and then pressed.
  • the isotropic conductive adhesive layer functions as an adhesive that bonds the electromagnetic wave shielding film of the present invention and the printed wiring board.
  • the isotropic conductive adhesive layer since the isotropic conductive adhesive layer has isotropic conductivity, it also functions as a shield layer for shielding electromagnetic waves.
  • the isotropic conductive adhesive layer contains a non-conductive filler.
  • the fluidity of the isotropic conductive adhesive layer is moderately lowered.
  • the isotropic conductive adhesive layer located at the corners of the steps is subjected to high pressure and becomes thin when the electromagnetic wave shielding film is pressed onto the high-stepped printed wiring board.
  • the strength of the isotropic conductive adhesive layer tends to decrease.
  • the isotropic conductive adhesive layer is cured.
  • the isotropic conductive adhesive layer located at the corners of the step is difficult to thin.
  • the isotropic conductive adhesive layer of the electromagnetic wave shielding film of the present invention is less likely to break.
  • the isotropic conductive adhesive layer contains a non-conductive filler, the non-conductive filler enters between the conductive fillers, and moderate flexibility is exhibited, and in the isotropic conductive adhesive layer after curing , flexibility is less likely to decrease.
  • the protective layer contains a protective layer filler. Therefore, the strength of the protective layer is increased.
  • the protective layer also functions as a support for supporting the isotropic conductive adhesive layer. Therefore, when the electromagnetic wave shielding film of the present invention is attached to a printed wiring board with a high stepped portion, or when the printed wiring board with an electromagnetic wave shielding film of the present invention attached thereto is used, the isotropic conductive adhesive layer is damaged. , can be prevented from breaking.
  • the ratio of the weight of the conductive filler to the weight of the conductive filler is 15.0 to 23.0. With such a ratio, the contents of the conductive filler and the non-conductive filler are well balanced, so that the flexibility of the isotropic conductive adhesive layer is increased. Therefore, when the electromagnetic wave shielding film of the present invention is attached to a printed wiring board with a high level difference, the isotropic conductive adhesive layer is less likely to be damaged. In addition, the level difference adaptability is improved, and a gap is less likely to occur at the level difference portion.
  • the isotropic conductive adhesive layer and the printed wiring board are likely to deteriorate due to accumulation of water vapor and the like.
  • the above ratio is less than 15.0, the ratio of the conductive filler will decrease, and the conductivity of the isotropic conductive adhesive layer will tend to decrease. If the above ratio exceeds 23.0, the ratio of the conductive filler increases, and the isotropic conductive adhesive layer becomes hard and brittle. Therefore, when the electromagnetic wave shielding film is attached to the printed wiring board with a high level difference, the isotropic conductive adhesive layer is likely to be damaged.
  • the ratio of the total weight of the conductive filler and the non-conductive filler to the weight of the protective layer filler is between 1.9 and 2.2.
  • the weight ratio of the conductive filler and the non-conductive filler contained in the isotropic conductive adhesive layer becomes moderately large, so that the isotropic conductive adhesive layer can be used as a protective layer. Hard to get softer. Therefore, it is possible to prevent the isotropic conductive adhesive layer from becoming too thin at the step portion during pressing.
  • the electromagnetic wave shielding film of the present invention when the electromagnetic wave shielding film of the present invention is attached to a high stepped printed wiring board, excessive pressure on the isotropic conductive adhesive layer can be dispersed, and the isotropic conductive adhesive layer at the stepped portion can be prevented from becoming too thin. As a result, the isotropic conductive adhesive layer is less likely to break. If the ratio is less than 1.9, the isotropic conductive adhesive layer is likely to break when the electromagnetic wave shielding film is pressed. When the above ratio exceeds 2.2, the bending resistance of the electromagnetic wave shielding film tends to decrease.
  • the conductive filler includes metal powder such as silver powder, copper powder, nickel powder, solder powder, aluminum powder, silver-coated copper powder obtained by silver-plating copper powder, polymer fine particles and glass. It is preferably at least one selected from the group consisting of metal-coated microparticles such as microparticles in which beads or the like are coated with metal. These materials have high conductivity and are suitable as conductive fillers.
  • the non-conductive filler is preferably at least one selected from the group consisting of polyphosphate, metal phosphinate and silica.
  • Non-conductive fillers made of these materials are suitable for moderately reducing the fluidity of the isotropic conductive adhesive layer.
  • the protective layer filler is selected from the group consisting of silica, clay, gypsum, carbon filler, calcium carbonate, barium sulfate, alumina oxide, beryllium oxide, zinc oxide, silicon carbide and silicon nitride. is preferably at least one.
  • Protective layer fillers made of these materials can favorably improve the strength of the protective layer.
  • the particle diameter D50 of the conductive filler is preferably 20 ⁇ m or less.
  • the particle diameter D50 of the non-conductive filler is preferably 20 ⁇ m or less.
  • the particle diameter D50 of the protective layer filler is preferably 20 ⁇ m or less. When the particle diameter D50 of these fillers is 20 ⁇ m or less, the thickness of the entire electromagnetic wave shielding film can be reduced.
  • the total weight ratio of the conductive filler and the non-conductive filler in the isotropic conductive adhesive layer is preferably 66 to 71% by weight.
  • the fluidity of the isotropic conductive adhesive layer tends to be high, and when attaching the electromagnetic shielding film to a high-step printed wiring board, , the isotropic conductive adhesive layer located at the corner of the step tends to be thin. Therefore, the isotropic conductive adhesive layer is easily damaged. As a result, breakage is likely to occur during pressing.
  • the isotropic conductive adhesive layer becomes hard and the flexibility of the electromagnetic wave shielding film as a whole is reduced, resulting in poor flexibility and temporary fixing properties. descend.
  • the weight ratio of the protective layer filler in the protective layer is preferably 20 to 40% by weight.
  • the weight ratio of the protective layer filler is within the above range, the strength of the protective layer is further improved. If the weight ratio of the protective layer filler is less than 20% by weight, it is difficult to increase the strength of the protective layer. When the weight ratio of the protective layer filler exceeds 40% by weight, the protective layer becomes too hard, and the flexibility of the electromagnetic wave shielding film as a whole tends to decrease.
  • the protective layer and the isotropic conductive adhesive layer may be in direct contact.
  • a shield layer containing silver or silver-coated copper powder may be formed between the protective layer and the adhesive layer of the electromagnetic shielding film.
  • migration of silver from the shield layer to the adhesive layer and migration of silver from the shield layer to the protective layer may occur.
  • the protective layer and the isotropic conductive adhesive layer are in direct contact, there is no metal shield layer between the protective layer and the isotropic conductive adhesive layer. No problem.
  • an electromagnetic wave shielding film that is less likely to be damaged even when placed on a substrate having a high level difference.
  • FIG. 1 is a cross-sectional view schematically showing an example of the electromagnetic wave shielding film of the present invention.
  • FIG. 2 is a cross-sectional view schematically showing an example of a high stepped printed wiring board provided with the electromagnetic wave shielding film of the present invention.
  • FIG. 3 is a plan view schematically showing a method for evaluating embeddability of an electromagnetic wave shielding film.
  • FIG. 4 is a cross-sectional view schematically showing an evaluation method for evaluating breakage after pressing of an electromagnetic wave shielding film.
  • the electromagnetic wave shielding film of the present invention will be specifically described below.
  • the present invention is not limited to the following embodiments, and can be appropriately modified and applied without changing the gist of the present invention.
  • FIG. 1 is a cross-sectional view schematically showing an example of the electromagnetic wave shielding film of the present invention.
  • FIG. 2 is a cross-sectional view schematically showing an example of a high stepped printed wiring board provided with the electromagnetic wave shielding film of the present invention.
  • the electromagnetic wave shielding film 1 shown in FIG. 1 includes a protective layer 10 and an isotropic conductive adhesive layer 20 laminated on the protective layer 10 .
  • the protective layer 10 contains a protective layer filler
  • the isotropic conductive adhesive layer 20 contains a resin component, a conductive filler, and a non-conductive filler.
  • the electromagnetic wave shielding film 1 is adhered to the high stepped printed wiring board 30.
  • a high step printed wiring board 30 shown in FIG. 2 has a base film 31 on which a printed circuit 32 including a ground circuit 32 a is formed, and a coverlay 33 provided on the base film 31 so as to cover the printed circuit 32 .
  • the high stepped printed wiring board 30 has a stepped portion 34 consisting of a corner portion 34a and a recessed portion 34b.
  • An opening 33a is formed in the coverlay 33 to expose the ground circuit 32a, and the isotropic conductive adhesive layer 20 and the ground circuit 32a are in contact with the isotropic conductive adhesive layer 20 in the opening 33a.
  • Adhesive layer 20 is filled. As a result, the isotropic conductive adhesive layer 20 and the ground circuit 32a are electrically connected, so that the electromagnetic wave shielding effect is enhanced.
  • the electromagnetic wave shielding film 1 When the electromagnetic wave shielding film 1 is attached to the high stepped printed wiring board 30, the electromagnetic wave shielding film 1 is arranged so that the isotropic conductive adhesive layer 20 is in contact with the coverlay 33 of the high stepped printed wiring board 30, It is then pressed.
  • the isotropic conductive adhesive layer 20 functions as an adhesive that bonds the electromagnetic wave shielding film 1 and the high stepped printed wiring board 30 together.
  • the isotropic conductive adhesive layer 20 since the isotropic conductive adhesive layer 20 has isotropic conductivity, it also functions as a shield layer for shielding electromagnetic waves.
  • the isotropic conductive adhesive layer 20 contains a non-conductive filler. As a result, the fluidity of the isotropic conductive adhesive layer 20 moderately decreases.
  • Some conventional electromagnetic wave shielding films have isotropic conductive adhesive layers with high fluidity. Therefore, when an electromagnetic wave shielding film having an isotropic conductive adhesive layer with high fluidity is pressed onto a high-stepped printed wiring board, the isotropic conductive adhesive layer located at the corners of the steps is subjected to high pressure and becomes thin. As a result, the strength of the isotropic conductive adhesive layer tends to decrease. In addition, in the high stepped printed wiring board to which the electromagnetic shielding film is adhered after pressing, the isotropic conductive adhesive layer is cured.
  • the fluidity of the isotropic conductive adhesive layer 20 is moderately low, so the isotropic conductive adhesive layer 20 located at the corner 34a of the step 34 is difficult to thin.
  • the isotropic conductive adhesive layer 20 relating to the electromagnetic wave shielding film 1 is less likely to be damaged.
  • the isotropic conductive adhesive layer 20 contains a non-conductive filler, the non-conductive filler enters between the conductive fillers, and moderate flexibility is exhibited, and the isotropic conductive adhesive layer after curing At 20, the flexibility is less likely to become low.
  • the protective layer 10 contains a protective layer filler. Therefore, the strength of the protective layer 10 is increased. When the strength of the protective layer 10 is high, the protective layer 10 also functions as a support for supporting the isotropic conductive adhesive layer 20 . Therefore, when the electromagnetic wave shielding film 1 is attached to the high stepped printed wiring board and when the high stepped printed wiring board 30 to which the electromagnetic wave shielding film 1 is attached is used, the isotropic conductive adhesive layer 20 is damaged and broken. condition can be prevented.
  • the ratio of the weight of the conductive filler to the weight of the conductive filler is 15.0 to 23.0.
  • the ratio is preferably 16.0 to 22.0, more preferably 16.0 to 20.0.
  • the contents of the conductive filler and the non-conductive filler are well balanced, so that the flexibility of the isotropic conductive adhesive layer is increased. Therefore, the isotropic conductive adhesive layer 20 is less likely to be damaged when the electromagnetic wave shielding film 1 is adhered to the high stepped printed wiring board 30 .
  • the level difference adaptability is improved, and a gap is less likely to occur at the level difference portion.
  • the isotropic conductive adhesive layer and the printed wiring board are likely to deteriorate due to accumulation of water vapor and the like.
  • a gap is less likely to form between the isotropic conductive adhesive layer 20 and the high stepped printed wiring board 30, and water vapor and the like are less likely to accumulate, resulting in higher moisture resistance.
  • the above ratio is less than 15.0, the ratio of the conductive filler will decrease, and the conductivity of the isotropic conductive adhesive layer will tend to decrease. If the above ratio exceeds 23.0, the ratio of the conductive filler increases, and the isotropic conductive adhesive layer becomes hard and brittle. Therefore, when the electromagnetic wave shielding film is attached to the printed wiring board with a high level difference, the isotropic conductive adhesive layer is likely to be damaged.
  • the ratio of the total weight of the conductive filler and the non-conductive filler to the weight of the protective layer filler is , from 1.9 to 2.2.
  • the ratio is preferably 1.9 to 2.1, more preferably 1.9 to 2.0.
  • the weight ratio of the conductive filler and the non-conductive filler contained in the isotropic conductive adhesive layer 20 becomes moderately large, so that the isotropic conductive adhesive layer 20 is protected. It is less likely to become soft than the layer 10 . Therefore, it is possible to prevent the isotropic conductive adhesive layer 20 from becoming too thin at the step portion during pressing.
  • the electromagnetic wave shielding film 1 when the electromagnetic wave shielding film 1 is attached to the high stepped printed wiring board 30, excessive pressure on the isotropic conductive adhesive layer 20 can be dispersed, and the isotropic conductive adhesive layer at the stepped portion can be dissipated. 20 can be prevented from becoming too thin. As a result, the isotropic conductive adhesive layer 20 is less likely to be damaged. If the ratio is less than 1.9, the isotropic conductive adhesive layer is likely to break when the electromagnetic wave shielding film is pressed. When the above ratio exceeds 2.2, the bending resistance of the electromagnetic wave shielding film tends to decrease.
  • the protective layer 10 and the isotropic conductive adhesive layer 20 are in direct contact.
  • a shield layer containing silver or silver-coated copper powder may be formed between the protective layer and the adhesive layer of the electromagnetic shielding film.
  • migration of silver from the shield layer to the adhesive layer and migration of silver from the shield layer to the protective layer may occur.
  • the protective layer 10 and the isotropic conductive adhesive layer 20 are in direct contact, there is no metal shield layer between the protective layer 10 and the isotropic conductive adhesive layer 20, so the migration problem does not arise.
  • the protective layer and the isotropic conductive adhesive layer do not have to be in direct contact.
  • a functional layer such as an anchor coat layer may be formed between the protective layer and the isotropic conductive adhesive layer.
  • a shield layer may be formed between the protective layer and the isotropic conductive adhesive layer. In this case, it is preferable to use a metal that is less susceptible to migration.
  • the resin component constituting the protective layer 10 is not particularly limited, but it is preferably composed of a thermoplastic resin composition, a thermosetting resin composition, an active energy ray-curable composition, or the like.
  • thermoplastic resin composition examples include, but are not limited to, styrene resin compositions, vinyl acetate resin compositions, polyester resin compositions, polyethylene resin compositions, polypropylene resin compositions, and imide resin compositions. , acrylic resin compositions, and the like.
  • thermosetting resin composition examples include, but are not limited to, epoxy-based resin compositions, urethane-based resin compositions, urethane-urea-based resin compositions, styrene-based resin compositions, phenol-based resin compositions, and melamine-based resin compositions. at least one resin composition selected from the group consisting of products, acrylic resin compositions and alkyd resin compositions.
  • active energy ray-curable composition examples include, but are not limited to, polymerizable compounds having at least two (meth)acryloyloxy groups in the molecule.
  • the protective layer 10 may be composed of a single material, or may be composed of two or more materials.
  • the protective layer 10 may optionally contain a curing accelerator, a tackifier, an antioxidant, a pigment, a dye, a plasticizer, an ultraviolet absorber, an antifoaming agent, a leveling agent, a filler, a flame retardant, and a viscosity adjuster. agents, anti-blocking agents and the like may also be included.
  • the thickness of the protective layer 10 is not particularly limited and can be appropriately set as necessary, but is preferably 1 to 15 ⁇ m, more preferably 3 to 10 ⁇ m. If the thickness of the protective layer is less than 1 ⁇ m, it is too thin to sufficiently protect the shield layer and the adhesive layer. If the thickness of the protective layer exceeds 15 ⁇ m, the protective layer is too thick to be bent, and the protective layer itself is likely to be damaged. Therefore, it becomes difficult to apply to members requiring bending resistance.
  • the material of the protective layer filler contained in the protective layer 10 is not particularly limited, but silica, clay, gypsum, carbon filler, calcium carbonate, barium sulfate, alumina oxide, beryllium oxide, zinc oxide, carbonization. At least one filler selected from the group consisting of silicon and silicon nitride is preferable. Among these, silica and carbon fillers are more preferable. Protective layer fillers made of these materials can favorably improve the strength of the protective layer.
  • the protective layer filler may be composed of one kind of material alone, or may be composed of two or more kinds of materials.
  • the particle diameter D 50 of the protective layer filler is preferably 20 ⁇ m or less, more preferably 0.1 to 10 ⁇ m, even more preferably 0.1 to 5 ⁇ m.
  • the particle diameter D50 of the protective layer filler is 20 ⁇ m or less, the thickness of the entire electromagnetic wave shielding film 1 can be reduced.
  • the weight ratio of the protective layer filler in the protective layer 10 is preferably 20 to 40% by weight, more preferably 30 to 39% by weight.
  • the strength of the protective layer 10 is further improved. If the weight ratio of the protective layer filler is less than 20% by weight, it is difficult to increase the strength of the protective layer.
  • the weight ratio of the protective layer filler exceeds 40% by weight, the protective layer becomes too hard, and the flexibility of the electromagnetic wave shielding film as a whole tends to decrease.
  • the isotropic conductive adhesive layer 20 contains a resin component, a conductive filler, and a non-conductive filler.
  • the resin component is not particularly limited, but may be composed of a thermosetting resin composition or a thermoplastic resin composition.
  • thermosetting resin compositions include phenolic resin compositions, epoxy resin compositions, urethane resin compositions, melamine resin compositions, polyamide resin compositions and alkyd resin compositions.
  • thermoplastic resin compositions include styrene-based resin compositions, vinyl acetate-based resin compositions, polyester-based resin compositions, polyethylene-based resin compositions, polypropylene-based resin compositions, imide-based resin compositions, and , and acrylic resin compositions.
  • the epoxy resin composition is more preferably an amide-modified epoxy resin composition.
  • These resin components are suitable as resin components that constitute the isotropic conductive adhesive layer 20 .
  • the resin component may be one of these alone, or may be a combination of two or more.
  • the weight ratio of the resin component in the isotropic conductive adhesive layer 20 is preferably 25-50% by weight, more preferably 28-35% by weight. If the weight ratio of the resin component is less than 25% by weight, the adhesiveness of the isotropic conductive adhesive layer tends to deteriorate. When the weight ratio of the resin component exceeds 50% by weight, it becomes difficult for the isotropic conductive adhesive layer to obtain isotropic conductivity.
  • the conductive filler is silver powder, copper powder, nickel powder, solder powder, aluminum powder, silver-coated copper powder obtained by plating copper powder with silver, polymer fine particles, glass beads, or the like coated with metal. It is preferably at least one selected from the group consisting of fine particles. Among these, silver powder, copper powder, and silver-coated copper powder are more preferable. These materials have high conductivity and are suitable as conductive fillers.
  • the particle diameter D50 of the conductive filler is preferably 20 ⁇ m or less, more preferably 1 to 18 ⁇ m, even more preferably 2 to 17 ⁇ m.
  • the particle diameter D50 of the conductive filler is 20 ⁇ m or less, the thickness of the entire electromagnetic wave shielding film 1 can be reduced.
  • the weight ratio of the conductive filler in the isotropic conductive adhesive layer 20 is preferably 50-70% by weight, more preferably 52-69% by weight. If the weight ratio of the conductive filler is less than 50% by weight, it becomes difficult for the isotropic conductive adhesive layer to obtain isotropic conductivity. If the weight ratio of the conductive filler exceeds 70% by weight, the isotropic conductive adhesive layer becomes too hard, and the flexibility of the electromagnetic wave shielding film as a whole tends to decrease.
  • the non-conductive filler is preferably at least one selected from the group consisting of polyphosphate, metal phosphinate and silica.
  • Non-conductive fillers made of these materials are suitable for moderately reducing the fluidity of the isotropic conductive adhesive layer.
  • polyphosphates melamine salts, methylamine salts, ethylamine salts, diethylamine salts, triethylamine salts, ethylenediamine salts, piperazine salts, pyridine salts, triazine salts, ammonium salts and the like can be used, with melamine salts being preferred.
  • phosphinic acid metal salt aluminum salt, sodium salt, potassium salt, magnesium salt, calcium salt and the like can be used, among which aluminum salt is preferable.
  • the particle diameter D 50 of the non-conductive filler is preferably 20 ⁇ m or less, more preferably 1 to 19 ⁇ m, even more preferably 1 to 18 ⁇ m.
  • the particle diameter D50 of the non-conductive filler is 20 ⁇ m or less, the thickness of the entire electromagnetic wave shielding film 1 can be reduced.
  • the weight ratio of the non-conductive filler in the isotropic conductive adhesive layer 20 is preferably 2 to 10 wt%, more preferably 3 to 9 wt%. If the weight percentage of the non-conductive filler is less than 2% by weight, the percentage of the conductive filler becomes excessive and the flexibility is impaired. If the weight ratio of the non-conductive filler exceeds 10% by weight, the ratio of the powdery non-conductive filler becomes excessive, resulting in a decrease in bulk strength and a decrease in adhesive strength.
  • the thickness of the isotropic conductive adhesive layer 20 is not particularly limited, but is preferably 5 to 30 ⁇ m, more preferably 8 to 20 ⁇ m.
  • the thickness of the isotropic conductive adhesive layer is less than 5 ⁇ m, the amount of the resin component constituting the isotropic conductive adhesive layer is small, and it is difficult to obtain sufficient adhesive performance.
  • the thickness of the isotropic conductive adhesive layer exceeds 30 ⁇ m, the entire layer becomes thick and the flexibility is likely to be lost.
  • the total weight ratio of the conductive filler and the non-conductive filler in the isotropic conductive adhesive layer 20 is preferably 66 to 71% by weight, more preferably 66 to 69% by weight. more preferred.
  • the fluidity of the isotropic conductive adhesive layer tends to be high, and when attaching the electromagnetic shielding film to a high-step printed wiring board, , the isotropic conductive adhesive layer located at the corner of the step tends to be thin. Therefore, the isotropic conductive adhesive layer is easily damaged. As a result, breakage is likely to occur during pressing.
  • the isotropic conductive adhesive layer becomes hard and the flexibility of the electromagnetic wave shielding film as a whole is reduced, resulting in poor flexibility and temporary fixing properties. descend.
  • Materials for the base film 31 and the coverlay 33 in the high stepped printed wiring board 30 are not particularly limited, but are preferably made of engineering plastics.
  • engineering plastics include resins such as polyethylene terephthalate, polypropylene, crosslinked polyethylene, polyester, polybenzimidazole, polyimide, polyimideamide, polyetherimide, and polyphenylene sulfide.
  • a polyphenylene sulfide film is preferred when flame retardancy is required, and a polyimide film is preferred when heat resistance is required.
  • the thickness of the base film 31 is preferably 10-40 ⁇ m.
  • the thickness of the coverlay 33 is preferably 20 to 50 ⁇ m.
  • the printed circuit 32 and the ground circuit 32a are not particularly limited, but can be formed by etching a conductive material or the like.
  • conductive materials include copper, nickel, silver, and gold.
  • the height of the step 34 in the high stepped printed wiring board 30 is not particularly limited, but is preferably 100 to 500 ⁇ m, more preferably 150 to 300 ⁇ m. Even if the high stepped printed wiring board 30 has a step 34 of such a height, the electromagnetic wave shielding film 1 arranged on the high stepped printed wiring board 30 is less likely to be damaged.
  • the opening 33a also becomes a step.
  • the electromagnetic wave shielding film 1 is highly adaptable to high steps. Therefore, the isotropic conductive adhesive layer 20 of the electromagnetic wave shielding film 1 corresponds to such openings 33a and can preferably fill the openings 33a. Therefore, a gap is less likely to occur between the isotropic conductive adhesive layer 20 and the ground circuit 32a. If a gap is formed between the isotropic conductive adhesive layer and the ground circuit, moisture may accumulate in the gap and cause deterioration. However, using the electromagnetic wave shielding film 1 makes it difficult for such a problem to occur. Therefore, moisture resistance can be improved.
  • the method of attaching the electromagnetic wave shielding film 1 to the high stepped printed wiring board 30 is not particularly limited, but after placing the electromagnetic wave shielding film 1 on the high stepped printed wiring board 30, for example, 150 to 200 ° C., 2 to 5 MPa, 1 A method of hot pressing under conditions of up to 60 minutes can be mentioned.
  • Example 1 A composition for an isotropic conductive adhesive layer and a composition for a protective layer having the compositions shown in Table 1 were prepared. Next, the protective layer composition was applied to the transfer film and heated at 100° C. for 2 minutes in an electric oven to prepare a protective layer having a thickness of 5 ⁇ m. Next, the composition for an isotropic conductive adhesive layer is applied on the release film that is peeled off before the electromagnetic wave shielding film is attached to the printed wiring board, and an isotropic conductive adhesive layer having a thickness of 15 ⁇ m is formed. formed. Thereafter, an isotropic conductive adhesive layer was overlaid on the protective layer and laminated at a temperature of 125° C. and a pressure of 0.5 MPa using a laminator to produce an electromagnetic wave shielding film according to Example 1.
  • Examples 2 to 5 and Comparative Examples 1 to 15 were prepared in the same manner as in Example 1 except that the compositions of the isotropic conductive adhesive layer composition and the protective layer composition were changed as shown in Table 1. An electromagnetic wave shielding film was produced.
  • the types of the non-conductive filler, conductive filler and protective layer filler shown in Table 1 and the particle size D50 are as follows.
  • Phosphinate trisdiethylphosphinate aluminum salt
  • particle size D50 3.0 ⁇ m
  • Silver-coated copper powder dendritic silver-coated copper powder
  • particle diameter D50 6.0 ⁇ m
  • Carbon Product name: Sheast SP, manufacturer: Tokai Carbon Co., Ltd.
  • particle diameter D50 0.095 ⁇ m
  • Silica trade name: SFP-20M, manufacturer: Denka Co., Ltd.
  • particle diameter D50 0.4 ⁇ m
  • FIG. 3 is a plan view schematically showing a method for evaluating embeddability of an electromagnetic wave shielding film.
  • the electromagnetic wave shielding film 1 was attached to the test printed wiring board 40 using a press under conditions of temperature: 170° C., time: 30 minutes, and pressure: 2 to 3 MPa.
  • the test printed wiring board 40 consists of two copper foil patterns 41 extending parallel to each other with a space therebetween provided on a base film (not shown), and a coverlay (thickness) made of polyimide covering the copper foil patterns.
  • the coverlay 42 had an opening 43 simulating a ground connection of 1.0 mm or 0.8 mm in diameter.
  • the electrical resistance value between the two copper foil patterns 41 formed on the test printed wiring board 40 was measured by the resistance meter 51 at the following times.
  • Initial after 5 times of pseudo-reflow operation exposed to 265°C for 1 second, after 250 hours at temperature: 85°C and humidity: 85%, after 500 hours at temperature: 85°C and humidity: 85% , after 750 hours at 85°C and 85% humidity, after 1000 hours at 85°C and 85% humidity, and after 3000 hours at 85°C and 85% humidity. .
  • Table 2 shows the results.
  • the electromagnetic wave shielding films according to Examples 1 to 4 had no cracks in the protective layer, or had only one crack of less than 100 ⁇ m.
  • those that were evaluated as x in the evaluation of bending resistance had a 1 mm thickness that may significantly affect the reduction in shielding properties after being attached to the printed wiring board. A plurality of cracks as described above were generated.
  • FIG. 4 is a cross-sectional view schematically showing an evaluation method for evaluating breakage after pressing of an electromagnetic wave shielding film.
  • a high level difference for testing having a base film 62 having a concave level difference and a pair of copper foil patterns 61 formed in parallel on the surface of the base film 62 so as to sandwich the concave level difference.
  • a printed wiring board 60 was prepared. The width of the concave step was 10 mm, and the depth of the concave step was 300 ⁇ m.
  • the electromagnetic wave shielding film of the present invention was excellent in evaluation of embeddability, evaluation of bending resistance, and evaluation of breakage after pressing. From these results, it was found that the electromagnetic wave shielding film of the present invention is less likely to be damaged even when placed on a substrate having a high level difference. That is, the electromagnetic wave shielding film of the present invention is highly adaptable to high steps. In addition, as shown in Table 3, it was found that the electromagnetic wave shielding film of the present invention was also excellent in evaluation of temporary fixing properties.

Abstract

The present invention provides an electromagnetic wave shield film that is not easily damaged even when placed on a high step-height substrate. The electromagnetic wave shield film comprises a protective layer and an isotropic conductive adhesive layer laminated on the protective layer, wherein the protective layer contains a protective layer filler, the isotropic conductive adhesive layer contains a resin component, a conductive filler, and a non-conductive filler, the ratio of the weight of the conductive filler to the weight of the non-conductive filler (the weight of the conductive filler/the weight of the non-conductive filler) is 15.0-23.0, and the ratio of the total weight of the conductive filler and the non-conductive filler to the weight of the protective layer filler ((the weight of the conductive filler + the weight of the non-conductive filler)/the weight of the protective layer filler) is 1.9-2.2.

Description

電磁波シールドフィルムelectromagnetic wave shielding film
本発明は、電磁波シールドフィルムに関する。 The present invention relates to an electromagnetic wave shielding film.
従来から、例えばフレキシブルプリント配線板（ＦＰＣ）などのプリント配線板に電磁波シールドフィルムを貼り付けて、外部からの電磁波をシールドすることが行われている。 2. Description of the Related Art Conventionally, an electromagnetic wave shielding film has been attached to a printed wiring board such as a flexible printed wiring board (FPC) to shield electromagnetic waves from the outside.
このような電磁波シールドフィルムとして特許文献１には、シールド層と、前記シールド層に積層された絶縁層とを備える電磁波シールドフィルムであって、前記絶縁層は、シリカ微粒子を含み、前記絶縁層中の前記シリカ微粒子の含有量は、１０～５０ｗｔ％であることを特徴とする電磁波シールドフィルムが記載されている。 As such an electromagnetic wave shielding film, Patent Document 1 discloses an electromagnetic wave shielding film comprising a shield layer and an insulating layer laminated on the shield layer, wherein the insulating layer contains silica fine particles, and in the insulating layer describes an electromagnetic wave shielding film characterized in that the content of said silica fine particles is 10 to 50 wt %.
特開２０１９－４６８７１号公報JP 2019-46871 A
近年、車載向け電子部品にも電磁波ノイズ対策が求められている。
車載向け電子部品には、高段差を有するプリント配線板（以下、「高段差プリント配線板」とも記載する）が多く使用される。
このような高段差プリント配線板に、スマートフォン等の電子部品に対して用いられる従来の電磁波シールドフィルムを用いると、従来の電磁波シールドフィルムは、高段差に対応できず、製造時や使用時に電磁波シールドフィルムが破損しやすくなる。これは以下の理由によると考えられる。 In recent years, there has been a demand for electromagnetic noise countermeasures for electronic components for automobiles.
2. Description of the Related Art A printed wiring board having a high level difference (hereinafter also referred to as a "high level printed wiring board") is often used for electronic components for vehicles.
If a conventional electromagnetic shielding film used for electronic parts such as smartphones is used for such a high-step printed wiring board, the conventional electromagnetic shielding film cannot cope with the high step, and it is difficult to shield electromagnetic waves during manufacturing and use. The film becomes easily damaged. This is believed to be due to the following reasons.
従来の電磁波シールドフィルムは熱プレスによりプリント配線板に配置される。この際、段差の角部で電磁波シールドフィルムに高い圧力がかかるので、電磁波シールドフィルムのシールド層に破断が生じやすくなるという問題がある。
また、上記のように高段差への電磁波シールドフィルムの貼付によって、シールド層に破断が生じなかった場合でも、電磁波シールドフィルムが段差の角部で折り曲げられることで、保護層に大きなクラックが生じる場合がある。
すなわち、特許文献１に記載の電磁波シールドフィルムでは、高段差への対応性が低いという問題がある。 A conventional electromagnetic wave shielding film is placed on a printed wiring board by hot pressing. At this time, since high pressure is applied to the electromagnetic wave shielding film at the corners of the steps, there is a problem that the shield layer of the electromagnetic wave shielding film is likely to break.
In addition, even if the shield layer is not broken by sticking the electromagnetic wave shielding film to the high step as described above, the electromagnetic wave shielding film may be bent at the corner of the step and cause a large crack in the protective layer. There is
In other words, the electromagnetic wave shielding film described in Patent Document 1 has a problem of low adaptability to high steps.
なお、高段差プリント配線板にシールド性を付与する方法として、高段差に対応可能な銀ペーストを塗工し、その後、レジストを塗工する方法もある。しかし、このような方法では、工数が多くなるという問題や、銀が絶縁素材にマイグレーションしてしまい高段差プリント配線板に形成された回路に短絡が生じやすくなるという問題がある。そのため、このような方法で電磁波シールド対策を行うことは嫌厭される傾向がある。 As a method of imparting a shielding property to a printed wiring board with a high level difference, there is also a method of applying a silver paste capable of coping with a high level difference and then applying a resist. However, such a method has a problem that the number of man-hours is increased, and a problem that silver migrates to an insulating material and short-circuiting easily occurs in a circuit formed on a printed wiring board with a high level difference. Therefore, there is a tendency to dislike taking electromagnetic wave shielding measures in this way.
本発明は、上記問題を鑑みてなされたものであり、本発明の目的は、高段差を有する基板に配置しても破損しにくい電磁波シールドフィルムを提供することである。 The present invention has been made in view of the above problems, and an object of the present invention is to provide an electromagnetic wave shielding film that is less likely to be damaged even when placed on a substrate having a high level difference.
本発明の電磁波シールドフィルムは、保護層と、上記保護層に積層された等方導電性接着剤層とを備え、上記保護層は、保護層用フィラーを含み、上記等方導電性接着剤層は、樹脂成分と、導電性フィラーと、非導電性フィラーとを含み、上記非導電性フィラーの重量に対する上記導電性フィラーの重量の割合（導電性フィラーの重量／非導電性フィラーの重量）は、１５．０～２３．０であり、上記保護層用フィラーの重量に対する上記導電性フィラー及び上記非導電性フィラーの合計重量の割合（（導電性フィラーの重量＋非導電性フィラーの重量）／保護層用フィラーの重量）は、１．９～２．２であることを特徴とする。 The electromagnetic wave shielding film of the present invention comprises a protective layer and an isotropic conductive adhesive layer laminated on the protective layer, the protective layer containing a protective layer filler, and the isotropic conductive adhesive layer contains a resin component, a conductive filler, and a non-conductive filler, and the ratio of the weight of the conductive filler to the weight of the non-conductive filler (weight of conductive filler/weight of non-conductive filler) is , 15.0 to 23.0, and the ratio of the total weight of the conductive filler and the non-conductive filler to the weight of the protective layer filler ((weight of conductive filler + weight of non-conductive filler) / The weight of the protective layer filler) is 1.9 to 2.2.
本発明の電磁波シールドフィルムは、プリント配線板に貼付されることになる。この際、等方導電性接着剤層がプリント配線板に接触するように本発明の電磁波シールドフィルムが配置され、その後プレスされる。
等方導電性接着剤層は、本発明の電磁波シールドフィルムとプリント配線板とを接着する接着剤として機能する。
また、等方導電性接着剤層は等方導電性を有するので、電磁波をシールドするシールド層としても機能する。 The electromagnetic wave shielding film of the present invention is attached to a printed wiring board. At this time, the electromagnetic wave shielding film of the present invention is arranged so that the isotropic conductive adhesive layer is in contact with the printed wiring board, and then pressed.
The isotropic conductive adhesive layer functions as an adhesive that bonds the electromagnetic wave shielding film of the present invention and the printed wiring board.
In addition, since the isotropic conductive adhesive layer has isotropic conductivity, it also functions as a shield layer for shielding electromagnetic waves.
本発明の電磁波シールドフィルムでは、等方導電性接着剤層が非導電性フィラーを含む。これにより等方導電性接着剤層の流動性が適度に低下する。
等方導電性接着剤層の流動性が高い場合、高段差プリント配線板に電磁波シールドフィルムをプレスする際、段差の角部に位置する等方導電性接着剤層は高い圧力を受け薄くなる。そのため、等方導電性接着剤層の強度が低下しやすくなる。また、プレス後の電磁波シールドフィルムが貼付された高段差プリント配線板では、等方導電性接着剤層が硬化することになる。電磁波シールドフィルムが貼付された高段差プリント配線板が繰り返し振動を受けると、段差の角部に位置する等方導電性接着剤層に繰り返し圧力がかかりやすくなる。上記の通り段差の角部に位置する等方導電性接着剤層は薄くなりやすく強度が低い傾向があるので、このような圧力がかかると、段差の角部を起点として、等方導電性接着剤層にクラックが生じやすくなる。また、等方導電性接着剤層に薄い部分があると、その部分が破断の起点となるおそれがある。
しかし、本発明の電磁波シールドフィルムでは、等方導電性接着剤層の流動性が適度に低いので、段差の角部に位置する等方導電性接着剤層は薄くなりにくい。その結果、本発明の電磁波シールドフィルムに係る等方導電性接着剤層は破損しにくくなる。また、等方導電性接着剤層が非導電性フィラーを含むことで、導電性フィラー間に非導電性フィラーが入り、適度な柔軟性が発現し、硬化後の等方導電性接着剤層において、可撓性が低くなりにくい。そのため、本発明の電磁波シールドフィルムが貼付された高段差プリント配線板が、繰り返し振動を受けたとしても、段差の部角を起点として、等方導電性接着剤層にクラックが生じにくくなる。また、等方導電性接着剤層に薄い部分が生じにくいので、プレス時に破断が生じにくい。 In the electromagnetic shielding film of the present invention, the isotropic conductive adhesive layer contains a non-conductive filler. As a result, the fluidity of the isotropic conductive adhesive layer is moderately lowered.
When the fluidity of the isotropic conductive adhesive layer is high, the isotropic conductive adhesive layer located at the corners of the steps is subjected to high pressure and becomes thin when the electromagnetic wave shielding film is pressed onto the high-stepped printed wiring board. As a result, the strength of the isotropic conductive adhesive layer tends to decrease. In addition, in the high stepped printed wiring board to which the electromagnetic shielding film is adhered after pressing, the isotropic conductive adhesive layer is cured. When a printed wiring board with a high level difference to which an electromagnetic wave shielding film is attached is subjected to repeated vibrations, repeated pressure is likely to be applied to the isotropic conductive adhesive layers located at the corners of the level difference. As described above, the isotropic conductive adhesive layer located at the corner of the step tends to be thin and weak, so when such pressure is applied, the isotropic conductive adhesive layer starts from the corner of the step. Cracks are likely to occur in the agent layer. In addition, if the isotropic conductive adhesive layer has a thin portion, that portion may become a starting point of breakage.
However, in the electromagnetic wave shielding film of the present invention, since the fluidity of the isotropic conductive adhesive layer is moderately low, the isotropic conductive adhesive layer located at the corners of the step is difficult to thin. As a result, the isotropic conductive adhesive layer of the electromagnetic wave shielding film of the present invention is less likely to break. In addition, since the isotropic conductive adhesive layer contains a non-conductive filler, the non-conductive filler enters between the conductive fillers, and moderate flexibility is exhibited, and in the isotropic conductive adhesive layer after curing , flexibility is less likely to decrease. Therefore, even if the high-stepped printed wiring board to which the electromagnetic wave shielding film of the present invention is adhered is subjected to repeated vibrations, cracks are less likely to occur in the isotropic conductive adhesive layer starting from the corners of the steps. Also, since thin portions are less likely to occur in the isotropic conductive adhesive layer, breakage is less likely to occur during pressing.
本発明の電磁波シールドフィルムでは、保護層が保護層用フィラーを含む。そのため、保護層の強度が高くなる。
保護層の強度が高いと、保護層が等方導電性接着剤層を支える支持体としても機能する。そのため、高段差プリント配線板に本発明の電磁波シールドフィルムを貼付する際、及び、本発明の電磁波シールドフィルムが貼付された高段差プリント配線板の使用時に、等方導電性接着剤層が破損し、破断状態になることを防ぐことができる。 In the electromagnetic wave shielding film of the present invention, the protective layer contains a protective layer filler. Therefore, the strength of the protective layer is increased.
When the strength of the protective layer is high, the protective layer also functions as a support for supporting the isotropic conductive adhesive layer. Therefore, when the electromagnetic wave shielding film of the present invention is attached to a printed wiring board with a high stepped portion, or when the printed wiring board with an electromagnetic wave shielding film of the present invention attached thereto is used, the isotropic conductive adhesive layer is damaged. , can be prevented from breaking.
本発明の電磁波シールドフィルムでは、上記導電性フィラーの重量に対する上記導電性フィラーの重量の割合（導電性フィラーの重量／非導電性フィラーの重量）は、１５．０～２３．０である。
このような割合であると、導電性フィラーと非導電性フィラーとの含有量のバランスが良いので、等方導電性接着剤層の柔軟性が高くなる。そのため、高段差プリント配線板に本発明の電磁波シールドフィルムを貼付した際に、等方導電性接着剤層が破損しにくくなる。また、段差対応性が高くなり段差部において隙間が生じにくくなる。等方導電性接着剤層とプリント配線板との間に隙間が生じると、水蒸気等がたまることにより等方導電性接着剤層やプリント配線板が劣化しやすくなる。しかし、本発明の電磁波シールドフィルムでは、等方導電性接着剤層とプリント配線板との間に隙間が生じにくく、水蒸気等がたまりにくいので、耐湿性が高くなる。
一方、上記割合が１５．０未満であると、導電性フィラーの割合が少なくなり、等方導電性接着剤層の導電性が低下しやすくなる。
上記割合が２３．０を超えると、導電性フィラーの割合が多くなり、等方導電性接着剤層が硬く脆くなってしまう。そのため、高段差プリント配線板に電磁波シールドフィルムを貼付した際に、等方導電性接着剤層が破損しやすくなる。 In the electromagnetic wave shielding film of the present invention, the ratio of the weight of the conductive filler to the weight of the conductive filler (weight of conductive filler/weight of non-conductive filler) is 15.0 to 23.0.
With such a ratio, the contents of the conductive filler and the non-conductive filler are well balanced, so that the flexibility of the isotropic conductive adhesive layer is increased. Therefore, when the electromagnetic wave shielding film of the present invention is attached to a printed wiring board with a high level difference, the isotropic conductive adhesive layer is less likely to be damaged. In addition, the level difference adaptability is improved, and a gap is less likely to occur at the level difference portion. If a gap occurs between the isotropic conductive adhesive layer and the printed wiring board, the isotropic conductive adhesive layer and the printed wiring board are likely to deteriorate due to accumulation of water vapor and the like. However, in the electromagnetic wave shielding film of the present invention, it is difficult for a gap to form between the isotropic conductive adhesive layer and the printed wiring board, and it is difficult for water vapor or the like to accumulate, so that the humidity resistance is improved.
On the other hand, if the above ratio is less than 15.0, the ratio of the conductive filler will decrease, and the conductivity of the isotropic conductive adhesive layer will tend to decrease.
If the above ratio exceeds 23.0, the ratio of the conductive filler increases, and the isotropic conductive adhesive layer becomes hard and brittle. Therefore, when the electromagnetic wave shielding film is attached to the printed wiring board with a high level difference, the isotropic conductive adhesive layer is likely to be damaged.
本発明の電磁波シールドフィルムでは、上記保護層用フィラーの重量に対する上記導電性フィラー及び上記非導電性フィラーの合計重量の割合（（導電性フィラーの重量＋非導電性フィラーの重量）／保護層用フィラーの重量）は、１．９～２．２である。
このような割合であると、等方導電性接着剤層に含まれる導電性フィラーの重量及び非導電性フィラーの重量割合が適度に大きくなるので、等方導電性接着剤層が、保護層に比べ柔らかくなりにくい。そのため、プレス時に段差部において等方導電性接着剤層が薄くなりすぎることを防ぐことができる。
また、高段差プリント配線板に本発明の電磁波シールドフィルムを貼付する際に、等方導電性接着剤層への過度な圧力を分散させることができ、段差部での等方導電性接着剤層が薄くなりすぎることを防ぐことができる。その結果、等方導電性接着剤層が破損しにくくなる。
上記割合が、１．９未満であると、電磁波シールドフィルムのプレス時に等方導電性接着剤層の破断が生じやすくなる。
上記割合が、２．２を超えると、電磁波シールドフィルムの耐屈曲性が低下しやすくなる。 In the electromagnetic wave shielding film of the present invention, the ratio of the total weight of the conductive filler and the non-conductive filler to the weight of the protective layer filler ((weight of conductive filler + weight of non-conductive filler) / for protective layer filler weight) is between 1.9 and 2.2.
With such a ratio, the weight ratio of the conductive filler and the non-conductive filler contained in the isotropic conductive adhesive layer becomes moderately large, so that the isotropic conductive adhesive layer can be used as a protective layer. Hard to get softer. Therefore, it is possible to prevent the isotropic conductive adhesive layer from becoming too thin at the step portion during pressing.
In addition, when the electromagnetic wave shielding film of the present invention is attached to a high stepped printed wiring board, excessive pressure on the isotropic conductive adhesive layer can be dispersed, and the isotropic conductive adhesive layer at the stepped portion can be prevented from becoming too thin. As a result, the isotropic conductive adhesive layer is less likely to break.
If the ratio is less than 1.9, the isotropic conductive adhesive layer is likely to break when the electromagnetic wave shielding film is pressed.
When the above ratio exceeds 2.2, the bending resistance of the electromagnetic wave shielding film tends to decrease.
本発明の電磁波シールドフィルムでは、上記導電性フィラーは、銀粉、銅粉、ニッケル粉、ハンダ粉、アルミニウム粉等の金属粉、銅粉に銀めっきを施した銀コート銅粉、高分子微粒子やガラスビーズ等を金属で被覆した微粒子等の金属被覆微粒子からなる群から選択される少なくとも１種であることが好ましい。
これらの材料は、導電性が高く導電性フィラーとして適している。 In the electromagnetic wave shielding film of the present invention, the conductive filler includes metal powder such as silver powder, copper powder, nickel powder, solder powder, aluminum powder, silver-coated copper powder obtained by silver-plating copper powder, polymer fine particles and glass. It is preferably at least one selected from the group consisting of metal-coated microparticles such as microparticles in which beads or the like are coated with metal.
These materials have high conductivity and are suitable as conductive fillers.
本発明の電磁波シールドフィルムでは、上記非導電性フィラーは、ポリリン酸塩、ホスフィン酸金属塩及びシリカからなる群から選択される少なくとも１種であることが好ましい。
これらの材料からなる非導電性フィラーは、等方導電性接着剤層の流動性を適度に低下させるために適している。 In the electromagnetic wave shielding film of the present invention, the non-conductive filler is preferably at least one selected from the group consisting of polyphosphate, metal phosphinate and silica.
Non-conductive fillers made of these materials are suitable for moderately reducing the fluidity of the isotropic conductive adhesive layer.
本発明の電磁波シールドフィルムでは、上記保護層用フィラーは、シリカ、クレー、石膏、カーボンフィラー、炭酸カルシウム、硫酸バリウム、酸化アルミナ、酸化ベリリウム、酸化亜鉛、炭化珪素及び窒化珪素からなる群から選択される少なくとも１種であることが好ましい。
これらの材料からなる保護層用フィラーは、好適に保護層の強度を向上させることができる。 In the electromagnetic wave shielding film of the present invention, the protective layer filler is selected from the group consisting of silica, clay, gypsum, carbon filler, calcium carbonate, barium sulfate, alumina oxide, beryllium oxide, zinc oxide, silicon carbide and silicon nitride. is preferably at least one.
Protective layer fillers made of these materials can favorably improve the strength of the protective layer.
本発明の電磁波シールドフィルムでは、上記導電性フィラーの粒子径Ｄ５０は、２０μｍ以下であることが好ましい。
本発明の電磁波シールドフィルムでは、上記非導電性フィラーの粒子径Ｄ５０は、２０μｍ以下であることが好ましい。
本発明の電磁波シールドフィルムでは、上記保護層用フィラーの粒子径Ｄ５０は、２０μｍ以下であることが好ましい。
これらのフィラーの粒子径Ｄ５０が、２０μｍ以下であると、電磁波シールドフィルム全体の厚みを薄くすることができる。 In the electromagnetic wave shielding film of the present invention, the particle diameter D50 of the conductive filler is preferably 20 μm or less.
In the electromagnetic wave shielding film of the present invention, the particle diameter D50 of the non-conductive filler is preferably 20 μm or less.
In the electromagnetic wave shielding film of the present invention, the particle diameter D50 of the protective layer filler is preferably 20 μm or less.
When the particle diameter D50 of these fillers is 20 μm or less, the thickness of the entire electromagnetic wave shielding film can be reduced.
本発明の電磁波シールドフィルムでは、上記等方導電性接着剤層に占める上記導電性フィラー及び上記非導電性フィラーの合計重量割合は、６６～７１重量％であることが好ましい。
導電性フィラー及び非導電性フィラーの合計重量割合が６６重量％未満であると、等方導電性接着剤層の流動性が高くなりやすく、高段差プリント配線板に電磁波シールドフィルムを貼付する際に、段差の角部に位置する等方導電性接着剤層は薄くなりやすくなる。そのため、等方導電性接着剤層が破損しやすくなる。その結果、プレス時に破断が生じ易くなる。
導電性フィラー及び非導電性フィラーの合計重量割合が７１重量％を超えると、等方導電性接着剤層が硬くなり、電磁波シールドフィルム全体の柔軟性が減少することにより屈曲性及び仮止め性が低下する。 In the electromagnetic wave shielding film of the present invention, the total weight ratio of the conductive filler and the non-conductive filler in the isotropic conductive adhesive layer is preferably 66 to 71% by weight.
When the total weight ratio of the conductive filler and the non-conductive filler is less than 66% by weight, the fluidity of the isotropic conductive adhesive layer tends to be high, and when attaching the electromagnetic shielding film to a high-step printed wiring board, , the isotropic conductive adhesive layer located at the corner of the step tends to be thin. Therefore, the isotropic conductive adhesive layer is easily damaged. As a result, breakage is likely to occur during pressing.
When the total weight ratio of the conductive filler and the non-conductive filler exceeds 71% by weight, the isotropic conductive adhesive layer becomes hard and the flexibility of the electromagnetic wave shielding film as a whole is reduced, resulting in poor flexibility and temporary fixing properties. descend.
本発明の電磁波シールドフィルムでは、上記保護層に占める上記保護層用フィラーの重量割合は、２０～４０重量％であることが好ましい。
保護層用フィラーの重量割合が上記範囲であると、保護層の強度がより向上する。
保護層用フィラーの重量割合が２０重量％未満であると、保護層の強度が高くなりにくい。
保護層用フィラーの重量割合が４０重量％を超えると、保護層が硬くなりすぎ、電磁波シールドフィルム全体の柔軟性が低下しやすくなる。 In the electromagnetic wave shielding film of the present invention, the weight ratio of the protective layer filler in the protective layer is preferably 20 to 40% by weight.
When the weight ratio of the protective layer filler is within the above range, the strength of the protective layer is further improved.
If the weight ratio of the protective layer filler is less than 20% by weight, it is difficult to increase the strength of the protective layer.
When the weight ratio of the protective layer filler exceeds 40% by weight, the protective layer becomes too hard, and the flexibility of the electromagnetic wave shielding film as a whole tends to decrease.
本発明の電磁波シールドフィルムでは、上記保護層と、上記等方導電性接着剤層とは直接接触していてもよい。
一般的に、電磁波シールドフィルムの保護層と接着剤層との間に銀や銀コート銅粉を含むシールド層が形成されることがある。このような構成の電磁波シールドフィルムではシールド層から接着剤層への銀のマイグレーションや、シールド層から保護層への銀のマイグレーションが生じる場合がある。
保護層と、等方導電性接着剤層とが直接接触している場合、保護層と、等方導電性接着剤層との間に金属からなるシールド層が無いので、上記のようなマイグレーションの問題は生じない。 In the electromagnetic wave shielding film of the present invention, the protective layer and the isotropic conductive adhesive layer may be in direct contact.
In general, a shield layer containing silver or silver-coated copper powder may be formed between the protective layer and the adhesive layer of the electromagnetic shielding film. In the electromagnetic wave shielding film having such a structure, migration of silver from the shield layer to the adhesive layer and migration of silver from the shield layer to the protective layer may occur.
When the protective layer and the isotropic conductive adhesive layer are in direct contact, there is no metal shield layer between the protective layer and the isotropic conductive adhesive layer. No problem.
本発明によれば、高段差を有する基板に配置しても破損しにくい電磁波シールドフィルムを提供することができる。 According to the present invention, it is possible to provide an electromagnetic wave shielding film that is less likely to be damaged even when placed on a substrate having a high level difference.
図１は、本発明の電磁波シールドフィルムの一例を模式的に示す断面図である。FIG. 1 is a cross-sectional view schematically showing an example of the electromagnetic wave shielding film of the present invention. 図２は、本発明の電磁波シールドフィルムを備える高段差プリント配線板の一例を模式的に示す断面図である。FIG. 2 is a cross-sectional view schematically showing an example of a high stepped printed wiring board provided with the electromagnetic wave shielding film of the present invention. 図３は、電磁波シールドフィルムの埋め込み性の評価方法を模式的に示す平面図である。FIG. 3 is a plan view schematically showing a method for evaluating embeddability of an electromagnetic wave shielding film. 図４は、電磁波シールドフィルムのプレス後の破断評価の評価方法を模式的に示す断面図である。FIG. 4 is a cross-sectional view schematically showing an evaluation method for evaluating breakage after pressing of an electromagnetic wave shielding film.
以下、本発明の電磁波シールドフィルムについて具体的に説明する。しかしながら、本発明は、以下の実施形態に限定されるものではなく、本発明の要旨を変更しない範囲において適宜変更して適用することができる。 The electromagnetic wave shielding film of the present invention will be specifically described below. However, the present invention is not limited to the following embodiments, and can be appropriately modified and applied without changing the gist of the present invention.
図１は、本発明の電磁波シールドフィルムの一例を模式的に示す断面図である。
図２は、本発明の電磁波シールドフィルムを備える高段差プリント配線板の一例を模式的に示す断面図である。 FIG. 1 is a cross-sectional view schematically showing an example of the electromagnetic wave shielding film of the present invention.
FIG. 2 is a cross-sectional view schematically showing an example of a high stepped printed wiring board provided with the electromagnetic wave shielding film of the present invention.
図１に示す電磁波シールドフィルム１は、保護層１０と、保護層１０に積層された等方導電性接着剤層２０とを備える。
保護層１０は、保護層用フィラーを含み、等方導電性接着剤層２０は、樹脂成分と、導電性フィラーと、非導電性フィラーとを含む。 The electromagnetic wave shielding film 1 shown in FIG. 1 includes a protective layer 10 and an isotropic conductive adhesive layer 20 laminated on the protective layer 10 .
The protective layer 10 contains a protective layer filler, and the isotropic conductive adhesive layer 20 contains a resin component, a conductive filler, and a non-conductive filler.
図２に示すように、電磁波シールドフィルム１は、高段差プリント配線板３０に貼付されることになる。
図２に示す高段差プリント配線板３０は、グランド回路３２ａを含むプリント回路３２が形成されたベースフィルム３１と、プリント回路３２を覆うようにベースフィルム３１上に設けられたカバーレイ３３を有する。
高段差プリント配線板３０は、角部３４ａ及び凹部３４ｂからなる段差３４を有している。 As shown in FIG. 2, the electromagnetic wave shielding film 1 is adhered to the high stepped printed wiring board 30. As shown in FIG.
A high step printed wiring board 30 shown in FIG. 2 has a base film 31 on which a printed circuit 32 including a ground circuit 32 a is formed, and a coverlay 33 provided on the base film 31 so as to cover the printed circuit 32 .
The high stepped printed wiring board 30 has a stepped portion 34 consisting of a corner portion 34a and a recessed portion 34b.
また、カバーレイ３３にはグランド回路３２ａを露出する開口部３３ａが形成されており、開口部３３ａには、等方導電性接着剤層２０とグランド回路３２ａとが接触するように等方導電性接着剤層２０が充填されている。
これにより等方導電性接着剤層２０とグランド回路３２ａとが電気的に接続されるので、電磁波シールド効果が高くなる。 An opening 33a is formed in the coverlay 33 to expose the ground circuit 32a, and the isotropic conductive adhesive layer 20 and the ground circuit 32a are in contact with the isotropic conductive adhesive layer 20 in the opening 33a. Adhesive layer 20 is filled.
As a result, the isotropic conductive adhesive layer 20 and the ground circuit 32a are electrically connected, so that the electromagnetic wave shielding effect is enhanced.
電磁波シールドフィルム１が、高段差プリント配線板３０に貼付される場合、等方導電性接着剤層２０が高段差プリント配線板３０のカバーレイ３３に接触するように電磁波シールドフィルム１が配置され、その後プレスされる。
等方導電性接着剤層２０は、電磁波シールドフィルム１と高段差プリント配線板３０とを接着する接着剤として機能する。
また、等方導電性接着剤層２０は等方導電性を有するので、電磁波をシールドするシールド層としても機能する。 When the electromagnetic wave shielding film 1 is attached to the high stepped printed wiring board 30, the electromagnetic wave shielding film 1 is arranged so that the isotropic conductive adhesive layer 20 is in contact with the coverlay 33 of the high stepped printed wiring board 30, It is then pressed.
The isotropic conductive adhesive layer 20 functions as an adhesive that bonds the electromagnetic wave shielding film 1 and the high stepped printed wiring board 30 together.
In addition, since the isotropic conductive adhesive layer 20 has isotropic conductivity, it also functions as a shield layer for shielding electromagnetic waves.
電磁波シールドフィルム１では、等方導電性接着剤層２０が非導電性フィラーを含む。これにより等方導電性接着剤層２０の流動性が適度に低下する。
従来の電磁波シールドフィルムには等方導電性接着剤層の流動性が高いものがある。そのため、高段差プリント配線板に等方導電性接着剤層の流動性が高い電磁波シールドフィルムをプレスする際、段差の角部に位置する等方導電性接着剤層は高い圧力を受け薄くなる。その結果、等方導電性接着剤層の強度が低下しやすくなる。また、プレス後の電磁波シールドフィルムが貼付された高段差プリント配線板では、等方導電性接着剤層が硬化することになる。等方導電性接着剤層の流動性が高い電磁波シールドフィルムが貼付された高段差プリント配線板が繰り返し振動を受けると、段差の角部に位置する等方導電性接着剤層に繰り返し圧力がかかりやすくなる。上記の通り、等方導電性接着剤層の流動性が高い電磁波シールドフィルムでは、段差の角部に位置する等方導電性接着剤層は薄くなりやすく強度が低い傾向があるので、このような圧力がかかると、段差の角部を起点として、等方導電性接着剤層にクラックが生じやすくなる。また、等方導電性接着剤層に薄い部分があると、その部分が破断の起点となるおそれがある。
しかし、電磁波シールドフィルム１では、等方導電性接着剤層２０の流動性が適度に低いので、段差３４の角部３４ａに位置する等方導電性接着剤層２０は薄くなりにくい。その結果、電磁波シールドフィルム１に係る等方導電性接着剤層２０は破損しにくくなる。また、等方導電性接着剤層２０が非導電性フィラーを含むことで、導電性フィラー間に非導電性フィラーが入り、適度な柔軟性が発現し、硬化後の等方導電性接着剤層２０において可撓性が低くなりにくい。そのため、電磁波シールドフィルム１が貼付された高段差プリント配線板３０が、繰り返し振動を受けたとしても、段差３４の角部３４ａを起点として、等方導電性接着剤層２０にクラックが生じにくくなる。また、等方導電性接着剤層２０に薄い部分が生じにくいので、プレス時に破断が生じにくい。 In the electromagnetic wave shielding film 1, the isotropic conductive adhesive layer 20 contains a non-conductive filler. As a result, the fluidity of the isotropic conductive adhesive layer 20 moderately decreases.
Some conventional electromagnetic wave shielding films have isotropic conductive adhesive layers with high fluidity. Therefore, when an electromagnetic wave shielding film having an isotropic conductive adhesive layer with high fluidity is pressed onto a high-stepped printed wiring board, the isotropic conductive adhesive layer located at the corners of the steps is subjected to high pressure and becomes thin. As a result, the strength of the isotropic conductive adhesive layer tends to decrease. In addition, in the high stepped printed wiring board to which the electromagnetic shielding film is adhered after pressing, the isotropic conductive adhesive layer is cured. When a high-stepped printed wiring board to which an electromagnetic wave shielding film with a highly fluid isotropic conductive adhesive layer is affixed is subjected to repeated vibrations, repeated pressure is applied to the isotropic conductive adhesive layer located at the corner of the step. easier. As described above, in the electromagnetic wave shielding film with the isotropic conductive adhesive layer having high fluidity, the isotropic conductive adhesive layer located at the corners of the steps tends to be thin and weak. When pressure is applied, cracks tend to occur in the isotropic conductive adhesive layer starting from the corners of the steps. In addition, if the isotropic conductive adhesive layer has a thin portion, that portion may become a starting point of breakage.
However, in the electromagnetic wave shielding film 1, the fluidity of the isotropic conductive adhesive layer 20 is moderately low, so the isotropic conductive adhesive layer 20 located at the corner 34a of the step 34 is difficult to thin. As a result, the isotropic conductive adhesive layer 20 relating to the electromagnetic wave shielding film 1 is less likely to be damaged. In addition, since the isotropic conductive adhesive layer 20 contains a non-conductive filler, the non-conductive filler enters between the conductive fillers, and moderate flexibility is exhibited, and the isotropic conductive adhesive layer after curing At 20, the flexibility is less likely to become low. Therefore, even if the high-stepped printed wiring board 30 to which the electromagnetic wave shielding film 1 is adhered is subjected to repeated vibrations, cracks are less likely to occur in the isotropic conductive adhesive layer 20 starting from the corners 34a of the steps 34. . In addition, since the isotropic conductive adhesive layer 20 is less likely to have a thin portion, it is less likely to break during pressing.
電磁波シールドフィルム１では、保護層１０が保護層用フィラーを含む。そのため、保護層１０の強度が高くなる。
保護層１０の強度が高いと、保護層１０が等方導電性接着剤層２０を支える支持体としても機能する。そのため、高段差プリント配線板に電磁波シールドフィルム１を貼付する際、及び、電磁波シールドフィルム１が貼付された高段差プリント配線板３０の使用時に、等方導電性接着剤層２０が破損し、破断状態になることを防ぐことができる。 In the electromagnetic wave shielding film 1, the protective layer 10 contains a protective layer filler. Therefore, the strength of the protective layer 10 is increased.
When the strength of the protective layer 10 is high, the protective layer 10 also functions as a support for supporting the isotropic conductive adhesive layer 20 . Therefore, when the electromagnetic wave shielding film 1 is attached to the high stepped printed wiring board and when the high stepped printed wiring board 30 to which the electromagnetic wave shielding film 1 is attached is used, the isotropic conductive adhesive layer 20 is damaged and broken. condition can be prevented.
電磁波シールドフィルム１では、導電性フィラーの重量に対する導電性フィラーの重量の割合（導電性フィラーの重量／非導電性フィラーの重量）は、１５．０～２３．０である。また当該割合は、１６．０～２２．０であることが好ましく、１６．０～２０．０であることがより好ましい。
このような割合であると、導電性フィラーと非導電性フィラーとの含有量のバランスが良いので、等方導電性接着剤層の柔軟性が高くなる。そのため、高段差プリント配線板３０に電磁波シールドフィルム１を貼付した際に、等方導電性接着剤層２０が破損しにくくなる。
また、段差対応性が高くなり段差部において隙間が生じにくくなる。等方導電性接着剤層とプリント配線板との間に隙間が生じると、水蒸気等がたまることにより等方導電性接着剤層やプリント配線板が劣化しやすくなる。しかし、電磁波シールドフィルム１では、等方導電性接着剤層２０と高段差プリント配線板３０との間に隙間が生じにくく、水蒸気等がたまりにくいので、耐湿性が高くなる。
一方、上記割合が１５．０未満であると、導電性フィラーの割合が少なくなり、等方導電性接着剤層の導電性が低下しやすくなる。
上記割合が２３．０を超えると、導電性フィラーの割合が多くなり、等方導電性接着剤層が硬く脆くなってしまう。そのため、高段差プリント配線板に電磁波シールドフィルムを貼付した際に、等方導電性接着剤層が破損しやすくなる。 In the electromagnetic wave shielding film 1, the ratio of the weight of the conductive filler to the weight of the conductive filler (weight of conductive filler/weight of non-conductive filler) is 15.0 to 23.0. The ratio is preferably 16.0 to 22.0, more preferably 16.0 to 20.0.
With such a ratio, the contents of the conductive filler and the non-conductive filler are well balanced, so that the flexibility of the isotropic conductive adhesive layer is increased. Therefore, the isotropic conductive adhesive layer 20 is less likely to be damaged when the electromagnetic wave shielding film 1 is adhered to the high stepped printed wiring board 30 .
In addition, the level difference adaptability is improved, and a gap is less likely to occur at the level difference portion. If a gap occurs between the isotropic conductive adhesive layer and the printed wiring board, the isotropic conductive adhesive layer and the printed wiring board are likely to deteriorate due to accumulation of water vapor and the like. However, in the electromagnetic wave shielding film 1, a gap is less likely to form between the isotropic conductive adhesive layer 20 and the high stepped printed wiring board 30, and water vapor and the like are less likely to accumulate, resulting in higher moisture resistance.
On the other hand, if the above ratio is less than 15.0, the ratio of the conductive filler will decrease, and the conductivity of the isotropic conductive adhesive layer will tend to decrease.
If the above ratio exceeds 23.0, the ratio of the conductive filler increases, and the isotropic conductive adhesive layer becomes hard and brittle. Therefore, when the electromagnetic wave shielding film is attached to the printed wiring board with a high level difference, the isotropic conductive adhesive layer is likely to be damaged.
電磁波シールドフィルム１では、保護層用フィラーの重量に対する導電性フィラー及び非導電性フィラーの合計重量の割合（（導電性フィラーの重量＋非導電性フィラーの重量）／保護層用フィラーの重量）は、１．９～２．２である。また当該割合は、１．９～２．１であることが好ましく、１．９～２．０であることがより好ましい。
このような割合であると、等方導電性接着剤層２０に含まれる導電性フィラーの重量及び非導電性フィラーの重量割合が適度に大きくなるので、等方導電性接着剤層２０が、保護層１０に比べ柔らかくなりにくい。そのため、プレス時に段差部において等方導電性接着剤層２０が薄くなりすぎることを防ぐことができる。
また、高段差プリント配線板３０に電磁波シールドフィルム１を貼付する際に、等方導電性接着剤層２０への過度な圧力を分散させることができ、段差部での等方導電性接着剤層２０が薄くなりすぎることを防ぐことができる。その結果、等方導電性接着剤層２０が破損しにくくなる。
上記割合が、１．９未満であると、電磁波シールドフィルムのプレス時に等方導電性接着剤層の破断が生じやすくなる。
上記割合が、２．２を超えると、電磁波シールドフィルムの耐屈曲性が低下しやすくなる。 In the electromagnetic wave shielding film 1, the ratio of the total weight of the conductive filler and the non-conductive filler to the weight of the protective layer filler ((weight of the conductive filler + weight of the non-conductive filler) / weight of the protective layer filler) is , from 1.9 to 2.2. The ratio is preferably 1.9 to 2.1, more preferably 1.9 to 2.0.
With such a ratio, the weight ratio of the conductive filler and the non-conductive filler contained in the isotropic conductive adhesive layer 20 becomes moderately large, so that the isotropic conductive adhesive layer 20 is protected. It is less likely to become soft than the layer 10 . Therefore, it is possible to prevent the isotropic conductive adhesive layer 20 from becoming too thin at the step portion during pressing.
In addition, when the electromagnetic wave shielding film 1 is attached to the high stepped printed wiring board 30, excessive pressure on the isotropic conductive adhesive layer 20 can be dispersed, and the isotropic conductive adhesive layer at the stepped portion can be dissipated. 20 can be prevented from becoming too thin. As a result, the isotropic conductive adhesive layer 20 is less likely to be damaged.
If the ratio is less than 1.9, the isotropic conductive adhesive layer is likely to break when the electromagnetic wave shielding film is pressed.
When the above ratio exceeds 2.2, the bending resistance of the electromagnetic wave shielding film tends to decrease.
電磁波シールドフィルム１では、保護層１０と、等方導電性接着剤層２０とは直接接触している。
一般的に、電磁波シールドフィルムの保護層と接着剤層との間に銀や銀コート銅粉を含むシールド層が形成されることがある。このような構成の電磁波シールドフィルムではシールド層から接着剤層への銀のマイグレーションや、シールド層から保護層への銀のマイグレーションが生じる場合がある。
保護層１０と、等方導電性接着剤層２０とが直接接触している場合、保護層１０と、等方導電性接着剤層２０との間に金属からなるシールド層が無いので、上記マイグレーションの問題は生じない。
なお、本発明の電磁波シールドフィルムでは、保護層と、等方導電性接着剤層とは直接接触していなくてもよい。この場合、保護層と等方導電性接着剤層との間には、アンカーコート層のような機能層が形成されていてもよい。
また、本発明の電磁波シールドフィルムでは、保護層と、等方導電性接着剤層との間にシールド層が形成されていてもよい。この場合、上記マイグレーションが生じにくい金属を用いることが好ましい。 In the electromagnetic wave shielding film 1, the protective layer 10 and the isotropic conductive adhesive layer 20 are in direct contact.
In general, a shield layer containing silver or silver-coated copper powder may be formed between the protective layer and the adhesive layer of the electromagnetic shielding film. In the electromagnetic wave shielding film having such a structure, migration of silver from the shield layer to the adhesive layer and migration of silver from the shield layer to the protective layer may occur.
When the protective layer 10 and the isotropic conductive adhesive layer 20 are in direct contact, there is no metal shield layer between the protective layer 10 and the isotropic conductive adhesive layer 20, so the migration problem does not arise.
In addition, in the electromagnetic shielding film of the present invention, the protective layer and the isotropic conductive adhesive layer do not have to be in direct contact. In this case, a functional layer such as an anchor coat layer may be formed between the protective layer and the isotropic conductive adhesive layer.
Further, in the electromagnetic wave shielding film of the present invention, a shield layer may be formed between the protective layer and the isotropic conductive adhesive layer. In this case, it is preferable to use a metal that is less susceptible to migration.
以下、電磁波シールドフィルム１の各構成について説明する。 Each configuration of the electromagnetic wave shielding film 1 will be described below.
（保護層）
電磁波シールドフィルム１において、保護層１０を構成する樹脂成分は特に限定されないが、熱可塑性樹脂組成物、熱硬化性樹脂組成物、活性エネルギー線硬化性組成物等から構成されていることが好ましい。 (protective layer)
In the electromagnetic wave shielding film 1, the resin component constituting the protective layer 10 is not particularly limited, but it is preferably composed of a thermoplastic resin composition, a thermosetting resin composition, an active energy ray-curable composition, or the like.
上記熱可塑性樹脂組成物としては、特に限定されないが、スチレン系樹脂組成物、酢酸ビニル系樹脂組成物、ポリエステル系樹脂組成物、ポリエチレン系樹脂組成物、ポリプロピレン系樹脂組成物、イミド系樹脂組成物、アクリル系樹脂組成物等が挙げられる。 Examples of the thermoplastic resin composition include, but are not limited to, styrene resin compositions, vinyl acetate resin compositions, polyester resin compositions, polyethylene resin compositions, polypropylene resin compositions, and imide resin compositions. , acrylic resin compositions, and the like.
上記熱硬化性樹脂組成物としては、特に限定されないが、エポキシ系樹脂組成物、ウレタン系樹脂組成物、ウレタンウレア系樹脂組成物、スチレン系樹脂組成物、フェノール系樹脂組成物、メラミン系樹脂組成物、アクリル系樹脂組成物及びアルキッド系樹脂組成物からなる群から選択される少なくとも１種の樹脂組成物が挙げられる。 Examples of the thermosetting resin composition include, but are not limited to, epoxy-based resin compositions, urethane-based resin compositions, urethane-urea-based resin compositions, styrene-based resin compositions, phenol-based resin compositions, and melamine-based resin compositions. at least one resin composition selected from the group consisting of products, acrylic resin compositions and alkyd resin compositions.
上記活性エネルギー線硬化性組成物としては、特に限定されないが、例えば、分子中に少なくとも２個の（メタ）アクリロイルオキシ基を有する重合性化合物等が挙げられる。 Examples of the active energy ray-curable composition include, but are not limited to, polymerizable compounds having at least two (meth)acryloyloxy groups in the molecule.
保護層１０は、１種単独の材料から構成されていてもよく、２種以上の材料から構成されていてもよい。 The protective layer 10 may be composed of a single material, or may be composed of two or more materials.
保護層１０には、必要に応じて、硬化促進剤、粘着性付与剤、酸化防止剤、顔料、染料、可塑剤、紫外線吸収剤、消泡剤、レベリング剤、充填剤、難燃剤、粘度調節剤、ブロッキング防止剤等が含まれていてもよい。 The protective layer 10 may optionally contain a curing accelerator, a tackifier, an antioxidant, a pigment, a dye, a plasticizer, an ultraviolet absorber, an antifoaming agent, a leveling agent, a filler, a flame retardant, and a viscosity adjuster. agents, anti-blocking agents and the like may also be included.
保護層１０の厚さは、特に限定されず、必要に応じて適宜設定することができるが、１～１５μｍであることが好ましく、３～１０μｍであることがより好ましい。
保護層の厚さが１μｍ未満であると、薄すぎるのでシールド層及び接着剤層を充分に保護しにくくなる。
保護層の厚さが１５μｍを超えると、厚すぎるので保護層が折り曲がりにくくなり、また、保護層自身が破損しやすくなる。そのため、耐折り曲げ性が要求される部材へ適用しにくくなる。 The thickness of the protective layer 10 is not particularly limited and can be appropriately set as necessary, but is preferably 1 to 15 μm, more preferably 3 to 10 μm.
If the thickness of the protective layer is less than 1 μm, it is too thin to sufficiently protect the shield layer and the adhesive layer.
If the thickness of the protective layer exceeds 15 μm, the protective layer is too thick to be bent, and the protective layer itself is likely to be damaged. Therefore, it becomes difficult to apply to members requiring bending resistance.
電磁波シールドフィルム１において、保護層１０に含まれる保護層用フィラーの材料は、特に限定されないが、シリカ、クレー、石膏、カーボンフィラー、炭酸カルシウム、硫酸バリウム、酸化アルミナ、酸化ベリリウム、酸化亜鉛、炭化珪素及び窒化珪素からなる群から選択される少なくとも１種であることが好ましい
これらの中では、シリカ及びカーボンフィラーであることがより好ましい。
これらの材料からなる保護層用フィラーは、好適に保護層の強度を向上させることができる。 In the electromagnetic wave shielding film 1, the material of the protective layer filler contained in the protective layer 10 is not particularly limited, but silica, clay, gypsum, carbon filler, calcium carbonate, barium sulfate, alumina oxide, beryllium oxide, zinc oxide, carbonization. At least one filler selected from the group consisting of silicon and silicon nitride is preferable. Among these, silica and carbon fillers are more preferable.
Protective layer fillers made of these materials can favorably improve the strength of the protective layer.
また、保護層用フィラーは１種の材料単独で構成されていてもよく、２種以上の材料から構成されていてもよい。 In addition, the protective layer filler may be composed of one kind of material alone, or may be composed of two or more kinds of materials.
保護層用フィラーの粒子径Ｄ５０は、２０μｍ以下であることが好ましく、０．１～１０μｍであることがより好ましく、０．１～５μｍであることがさらに好ましい。
保護層用フィラーの粒子径Ｄ５０が、２０μｍ以下であると、電磁波シールドフィルム１全体の厚みを薄くすることができる。 The particle diameter D 50 of the protective layer filler is preferably 20 μm or less, more preferably 0.1 to 10 μm, even more preferably 0.1 to 5 μm.
When the particle diameter D50 of the protective layer filler is 20 μm or less, the thickness of the entire electromagnetic wave shielding film 1 can be reduced.
電磁波シールドフィルム１では、保護層１０に占める保護層用フィラーの重量割合は、２０～４０重量％であることが好ましく、３０～３９重量％であることがより好ましい。
保護層用フィラーの重量割合が上記範囲であると、保護層１０の強度がより向上する。
保護層用フィラーの重量割合が２０重量％未満であると、保護層の強度が高くなりにくい。
保護層用フィラーの重量割合が４０重量％を超えると、保護層が硬くなりすぎ、電磁波シールドフィルム全体の柔軟性が低下しやすくなる。 In the electromagnetic wave shielding film 1, the weight ratio of the protective layer filler in the protective layer 10 is preferably 20 to 40% by weight, more preferably 30 to 39% by weight.
When the weight ratio of the protective layer filler is within the above range, the strength of the protective layer 10 is further improved.
If the weight ratio of the protective layer filler is less than 20% by weight, it is difficult to increase the strength of the protective layer.
When the weight ratio of the protective layer filler exceeds 40% by weight, the protective layer becomes too hard, and the flexibility of the electromagnetic wave shielding film as a whole tends to decrease.
（等方導電性接着剤層）
等方導電性接着剤層２０は、樹脂成分と、導電性フィラーと、非導電性フィラーとを含む。 (Isotropic conductive adhesive layer)
The isotropic conductive adhesive layer 20 contains a resin component, a conductive filler, and a non-conductive filler.
電磁波シールドフィルム１において、樹脂成分は、特に限定されないが、熱硬化性樹脂組成物からなっていてもよく、熱可塑性樹脂組成物からなっていてもよい。 In the electromagnetic wave shielding film 1, the resin component is not particularly limited, but may be composed of a thermosetting resin composition or a thermoplastic resin composition.
熱硬化性樹脂組成物としては、例えば、フェノール系樹脂組成物、エポキシ系樹脂組成物、ウレタン系樹脂組成物、メラミン系樹脂組成物、ポリアミド系樹脂組成物及びアルキッド系樹脂組成物等が挙げられる。
また、熱可塑性樹脂組成物としては、例えば、スチレン系樹脂組成物、酢酸ビニル系樹脂組成物、ポリエステル系樹脂組成物、ポリエチレン系樹脂組成物、ポリプロピレン系樹脂組成物、イミド系樹脂組成物、及び、アクリル系樹脂組成物が挙げられる。
また、エポキシ樹脂組成物としては、アミド変性エポキシ樹脂組成物であることがより好ましい。
これらの樹脂成分は、等方導電性接着剤層２０を構成する樹脂成分として適している。
樹脂成分はこれらの１種単独であってもよく、２種以上の組み合わせであってもよい。 Examples of thermosetting resin compositions include phenolic resin compositions, epoxy resin compositions, urethane resin compositions, melamine resin compositions, polyamide resin compositions and alkyd resin compositions. .
Examples of thermoplastic resin compositions include styrene-based resin compositions, vinyl acetate-based resin compositions, polyester-based resin compositions, polyethylene-based resin compositions, polypropylene-based resin compositions, imide-based resin compositions, and , and acrylic resin compositions.
Further, the epoxy resin composition is more preferably an amide-modified epoxy resin composition.
These resin components are suitable as resin components that constitute the isotropic conductive adhesive layer 20 .
The resin component may be one of these alone, or may be a combination of two or more.
電磁波シールドフィルム１において、等方導電性接着剤層２０における樹脂成分の重量割合は、２５～５０重量％であることが好ましく、２８～３５重量％であることがより好ましい。
樹脂成分の重量割合が２５重量％未満であると、等方導電性接着剤層の接着性が低下しやすくなる。
樹脂成分の重量割合が５０重量％を超えると、等方導電性接着剤層が等方導電性を得られにくくなる。 In the electromagnetic wave shielding film 1, the weight ratio of the resin component in the isotropic conductive adhesive layer 20 is preferably 25-50% by weight, more preferably 28-35% by weight.
If the weight ratio of the resin component is less than 25% by weight, the adhesiveness of the isotropic conductive adhesive layer tends to deteriorate.
When the weight ratio of the resin component exceeds 50% by weight, it becomes difficult for the isotropic conductive adhesive layer to obtain isotropic conductivity.
電磁波シールドフィルム１において、導電性フィラーは、銀粉、銅粉、ニッケル粉、ハンダ粉、アルミニウム粉、銅粉に銀めっきを施した銀コート銅粉、高分子微粒子やガラスビーズ等を金属で被覆した微粒子からなる群から選択される少なくとも１種であることが好ましい。
これらの中では、銀粉、銅粉、銀コート銅粉であることがより好ましい。
これらの材料は、導電性が高く導電性フィラーとして適している。 In the electromagnetic wave shielding film 1, the conductive filler is silver powder, copper powder, nickel powder, solder powder, aluminum powder, silver-coated copper powder obtained by plating copper powder with silver, polymer fine particles, glass beads, or the like coated with metal. It is preferably at least one selected from the group consisting of fine particles.
Among these, silver powder, copper powder, and silver-coated copper powder are more preferable.
These materials have high conductivity and are suitable as conductive fillers.
導電性フィラーの粒子径Ｄ５０は、２０μｍ以下であることが好ましく、１～１８μｍであることがより好ましく、２～１７μｍであることがさらに好ましい。
導電性フィラーの粒子径Ｄ５０が、２０μｍ以下であると、電磁波シールドフィルム１全体の厚みを薄くすることができる。 The particle diameter D50 of the conductive filler is preferably 20 μm or less, more preferably 1 to 18 μm, even more preferably 2 to 17 μm.
When the particle diameter D50 of the conductive filler is 20 μm or less, the thickness of the entire electromagnetic wave shielding film 1 can be reduced.
電磁波シールドフィルム１において、等方導電性接着剤層２０における導電性フィラーの重量割合は、５０～７０重量％であることが好ましく、５２～６９重量％であることがより好ましい。
導電性フィラーの重量割合が５０重量％未満であると、等方導電性接着剤層が等方導電性を得られにくくなる。
導電性フィラーの重量割合が７０重量％を超えると、等方導電性接着剤層が硬くなりすぎ、電磁波シールドフィルム全体の柔軟性が低下しやすくなる。 In the electromagnetic wave shielding film 1, the weight ratio of the conductive filler in the isotropic conductive adhesive layer 20 is preferably 50-70% by weight, more preferably 52-69% by weight.
If the weight ratio of the conductive filler is less than 50% by weight, it becomes difficult for the isotropic conductive adhesive layer to obtain isotropic conductivity.
If the weight ratio of the conductive filler exceeds 70% by weight, the isotropic conductive adhesive layer becomes too hard, and the flexibility of the electromagnetic wave shielding film as a whole tends to decrease.
電磁波シールドフィルム１において、非導電性フィラーは、ポリリン酸塩、ホスフィン酸金属塩及びシリカからなる群から選択される少なくとも１種であることが好ましい。
これらの材料からなる非導電性フィラーは、等方導電性接着剤層の流動性を適度に低下させるために適している。
ポリリン酸塩としては、メラミン塩、メチルアミン塩、エチルアミン塩、ジエチルアミン塩、トリエチルアミン塩、エチレンジアミン塩、ピペラジン塩、ピリジン塩、トリアジン塩、及びアンモニウム塩等を用いることができ、中でもメラミン塩が好ましい。
ホスフィン酸金属塩としては、アルミニウム塩、ナトリウム塩、カリウム塩、マグネシウム塩、及びカルシウム塩等を用いることができ、中でもアルミニウム塩が好ましい。 In the electromagnetic wave shielding film 1, the non-conductive filler is preferably at least one selected from the group consisting of polyphosphate, metal phosphinate and silica.
Non-conductive fillers made of these materials are suitable for moderately reducing the fluidity of the isotropic conductive adhesive layer.
As polyphosphates, melamine salts, methylamine salts, ethylamine salts, diethylamine salts, triethylamine salts, ethylenediamine salts, piperazine salts, pyridine salts, triazine salts, ammonium salts and the like can be used, with melamine salts being preferred.
As the phosphinic acid metal salt, aluminum salt, sodium salt, potassium salt, magnesium salt, calcium salt and the like can be used, among which aluminum salt is preferable.
非導電性フィラーの粒子径Ｄ５０は、２０μｍ以下であることが好ましく、１～１９μｍであることがより好ましく、１～１８μｍであることがさらに好ましい。
非導電性フィラーの粒子径Ｄ５０が、２０μｍ以下であると、電磁波シールドフィルム１全体の厚みを薄くすることができる。 The particle diameter D 50 of the non-conductive filler is preferably 20 μm or less, more preferably 1 to 19 μm, even more preferably 1 to 18 μm.
When the particle diameter D50 of the non-conductive filler is 20 μm or less, the thickness of the entire electromagnetic wave shielding film 1 can be reduced.
電磁波シールドフィルム１において、等方導電性接着剤層２０における非導電性フィラーの重量割合は、２～１０重量％であることが好ましく、３～９重量％であることがより好ましい。
非導電性フィラーの重量割合が２重量％未満である場合、導電性フィラーの割合が過剰となり可撓性が損なわれる。
非導電性フィラーの重量割合が１０重量％を超える場合、粉体である非導電性フィラーの割合が過剰となりバルク強度が低下し接着力が低下する。 In the electromagnetic wave shielding film 1, the weight ratio of the non-conductive filler in the isotropic conductive adhesive layer 20 is preferably 2 to 10 wt%, more preferably 3 to 9 wt%.
If the weight percentage of the non-conductive filler is less than 2% by weight, the percentage of the conductive filler becomes excessive and the flexibility is impaired.
If the weight ratio of the non-conductive filler exceeds 10% by weight, the ratio of the powdery non-conductive filler becomes excessive, resulting in a decrease in bulk strength and a decrease in adhesive strength.
電磁波シールドフィルム１において、等方導電性接着剤層２０の厚さは特に限定されないが、５～３０μｍであることが好ましく、８～２０μｍであることがより好ましい。
等方導電性接着剤層の厚さが５μｍ未満であると、等方導電性接着剤層を構成する樹脂成分の量が少ないため、充分な接着性能が得られにくい。
等方導電性接着剤層の厚さが３０μｍを超えると、全体が厚くなり、柔軟性が失われやすい。 In the electromagnetic wave shielding film 1, the thickness of the isotropic conductive adhesive layer 20 is not particularly limited, but is preferably 5 to 30 μm, more preferably 8 to 20 μm.
When the thickness of the isotropic conductive adhesive layer is less than 5 μm, the amount of the resin component constituting the isotropic conductive adhesive layer is small, and it is difficult to obtain sufficient adhesive performance.
When the thickness of the isotropic conductive adhesive layer exceeds 30 μm, the entire layer becomes thick and the flexibility is likely to be lost.
電磁波シールドフィルム１では、等方導電性接着剤層２０に占める導電性フィラー及び非導電性フィラーの合計重量割合は、６６～７１重量％であることが好ましく、６６～６９重量％であることがより好ましい。
導電性フィラー及び非導電性フィラーの合計重量割合が６６重量％未満であると、等方導電性接着剤層の流動性が高くなりやすく、高段差プリント配線板に電磁波シールドフィルムを貼付する際に、段差の角部に位置する等方導電性接着剤層は薄くなりやすくなる。そのため、等方導電性接着剤層が破損しやすくなる。その結果、プレス時に破断が生じ易くなる。
導電性フィラー及び非導電性フィラーの合計重量割合が７１重量％を超えると、等方導電性接着剤層が硬くなり、電磁波シールドフィルム全体の柔軟性が減少することにより屈曲性及び仮止め性が低下する。 In the electromagnetic wave shielding film 1, the total weight ratio of the conductive filler and the non-conductive filler in the isotropic conductive adhesive layer 20 is preferably 66 to 71% by weight, more preferably 66 to 69% by weight. more preferred.
When the total weight ratio of the conductive filler and the non-conductive filler is less than 66% by weight, the fluidity of the isotropic conductive adhesive layer tends to be high, and when attaching the electromagnetic shielding film to a high-step printed wiring board, , the isotropic conductive adhesive layer located at the corner of the step tends to be thin. Therefore, the isotropic conductive adhesive layer is easily damaged. As a result, breakage is likely to occur during pressing.
When the total weight ratio of the conductive filler and the non-conductive filler exceeds 71% by weight, the isotropic conductive adhesive layer becomes hard and the flexibility of the electromagnetic wave shielding film as a whole is reduced, resulting in poor flexibility and temporary fixing properties. descend.
次に、高段差プリント配線板３０の各構成について説明する。 Next, each configuration of high stepped printed wiring board 30 will be described.
高段差プリント配線板３０において、ベースフィルム３１及びカバーレイ３３の材料は、特に限定されないが、エンジニアリングプラスチックからなることが好ましい。
このようなエンジニアリングプラスチックとしては、例えば、ポリエチレンテレフタレート、ポリプロピレン、架橋ポリエチレン、ポリエステル、ポリベンズイミダゾール、ポリイミド、ポリイミドアミド、ポリエーテルイミド、ポリフェニレンサルファイドなどの樹脂が挙げられる。
また、これらのエンジニアリングプラスチックの内、難燃性が要求される場合には、ポリフェニレンサルファイドフィルムが望ましく、耐熱性が要求される場合にはポリイミドフィルムが好ましい。なお、ベースフィルム３１の厚みは、１０～４０μｍであることが好ましい。また、カバーレイ３３の厚みは、２０～５０μｍであることが好ましい。 Materials for the base film 31 and the coverlay 33 in the high stepped printed wiring board 30 are not particularly limited, but are preferably made of engineering plastics.
Examples of such engineering plastics include resins such as polyethylene terephthalate, polypropylene, crosslinked polyethylene, polyester, polybenzimidazole, polyimide, polyimideamide, polyetherimide, and polyphenylene sulfide.
Among these engineering plastics, a polyphenylene sulfide film is preferred when flame retardancy is required, and a polyimide film is preferred when heat resistance is required. The thickness of the base film 31 is preferably 10-40 μm. Moreover, the thickness of the coverlay 33 is preferably 20 to 50 μm.
プリント回路３２及びグランド回路３２ａは、特に限定されないが、導電材料をエッチング処理すること等により形成することができる。
導電材料としては、銅、ニッケル、銀、金等が挙げられる。 The printed circuit 32 and the ground circuit 32a are not particularly limited, but can be formed by etching a conductive material or the like.
Examples of conductive materials include copper, nickel, silver, and gold.
高段差プリント配線板３０において段差３４の高さは、特に限定されないが、１００～５００μｍであることが好ましく、１５０～３００μｍであることがより好ましい。
高段差プリント配線板３０がこのような高さの段差３４を有していたとしても、高段差プリント配線板３０に配置された電磁波シールドフィルム１は破損しにくい。 The height of the step 34 in the high stepped printed wiring board 30 is not particularly limited, but is preferably 100 to 500 μm, more preferably 150 to 300 μm.
Even if the high stepped printed wiring board 30 has a step 34 of such a height, the electromagnetic wave shielding film 1 arranged on the high stepped printed wiring board 30 is less likely to be damaged.
なお、高段差プリント配線板３０においては、開口部３３ａも段差になる。
これまで説明してきたように、電磁波シールドフィルム１は、高段差対応性が高い。そのため、電磁波シールドフィルム１の等方導電性接着剤層２０は、このような開口部３３ａに対応し、好適に開口部３３ａを充填することができる。従って、等方導電性接着剤層２０とグランド回路３２ａとの間には、隙間が生じにくい。
等方導電性接着剤層とグランド回路との間に隙間が生じると、隙間に水分がたまり、劣化の起点となる場合がある。しかし、電磁波シールドフィルム１を用いるとこのような問題は生じにくい。そのため、耐湿性を向上させることができる。 In addition, in the high stepped printed wiring board 30, the opening 33a also becomes a step.
As described above, the electromagnetic wave shielding film 1 is highly adaptable to high steps. Therefore, the isotropic conductive adhesive layer 20 of the electromagnetic wave shielding film 1 corresponds to such openings 33a and can preferably fill the openings 33a. Therefore, a gap is less likely to occur between the isotropic conductive adhesive layer 20 and the ground circuit 32a.
If a gap is formed between the isotropic conductive adhesive layer and the ground circuit, moisture may accumulate in the gap and cause deterioration. However, using the electromagnetic wave shielding film 1 makes it difficult for such a problem to occur. Therefore, moisture resistance can be improved.
電磁波シールドフィルム１を高段差プリント配線板３０に貼付する方法は、特に限定されないが、高段差プリント配線板３０に電磁波シールドフィルム１を配置した後、例えば、１５０～２００℃、２～５ＭＰａ、１～６０ｍｉｎの条件で熱プレスする方法が挙げられる。 The method of attaching the electromagnetic wave shielding film 1 to the high stepped printed wiring board 30 is not particularly limited, but after placing the electromagnetic wave shielding film 1 on the high stepped printed wiring board 30, for example, 150 to 200 ° C., 2 to 5 MPa, 1 A method of hot pressing under conditions of up to 60 minutes can be mentioned.
以下に本発明をより具体的に説明する実施例を示すが、本発明はこれらの実施例に限定されるものではない。 EXAMPLES The present invention will be described below in more detail with examples, but the present invention is not limited to these examples.
（実施例１）
表１に示す組成の等方導電性接着剤層用組成物及び保護層用組成物を作製した。
次に、転写フィルムに保護層用組成物を塗工し、電気オーブンを用い、１００℃で２分間加熱し、厚さ５μｍの保護層を作製した。
次に、電磁波シールドフィルムがプリント配線板へ貼付される前に剥離される離形フィルムの上に等方導電性接着剤層用組成物を塗布し、厚さ１５μｍの等方導電性接着剤層を形成した。その後、保護層に、等方導電性接着剤層を重ね、ラミネーターを用い、温度：１２５℃、圧力０．５ＭＰａでラミネートし、実施例１に係る電磁波シールドフィルムを製造した。 (Example 1)
A composition for an isotropic conductive adhesive layer and a composition for a protective layer having the compositions shown in Table 1 were prepared.
Next, the protective layer composition was applied to the transfer film and heated at 100° C. for 2 minutes in an electric oven to prepare a protective layer having a thickness of 5 μm.
Next, the composition for an isotropic conductive adhesive layer is applied on the release film that is peeled off before the electromagnetic wave shielding film is attached to the printed wiring board, and an isotropic conductive adhesive layer having a thickness of 15 μm is formed. formed. Thereafter, an isotropic conductive adhesive layer was overlaid on the protective layer and laminated at a temperature of 125° C. and a pressure of 0.5 MPa using a laminator to produce an electromagnetic wave shielding film according to Example 1.
（実施例２）～（実施例５）及び（比較例１）～（比較例１５）
等方導電性接着剤層用組成物及び保護層用組成物の組成を表１に示すように変更した以外は、実施例１と同様にして、実施例２～５及び比較例１～１５に係る電磁波シールドフィルムを製造した。 (Example 2) to (Example 5) and (Comparative Example 1) to (Comparative Example 15)
Examples 2 to 5 and Comparative Examples 1 to 15 were prepared in the same manner as in Example 1 except that the compositions of the isotropic conductive adhesive layer composition and the protective layer composition were changed as shown in Table 1. An electromagnetic wave shielding film was produced.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
表１に示す非導電性フィラー、導電性フィラー及び保護層用フィラーの種類、及び、粒子径Ｄ５０は以下の通りである。
ホスフィン酸塩：トリスジエチルホスフィン酸アルミニウム塩、粒子径Ｄ５０：３．０μｍ
銀コート銅粉：樹枝状の銀コート銅粉、粒子径Ｄ５０：６．０μｍ
カーボン：商品名：Ｓｈｅａｓｔ　ＳＰ、製造元：東海カーボン株式会社、粒子径Ｄ５０：０．０９５μｍ
シリカ：商品名：ＳＦＰ－２０Ｍ、製造元：デンカ株式会社、粒子径Ｄ５０：０．４μｍ The types of the non-conductive filler, conductive filler and protective layer filler shown in Table 1 and the particle size D50 are as follows.
Phosphinate: trisdiethylphosphinate aluminum salt, particle size D50 : 3.0 µm
Silver-coated copper powder: dendritic silver-coated copper powder, particle diameter D50 : 6.0 µm
Carbon: Product name: Sheast SP, manufacturer: Tokai Carbon Co., Ltd., particle diameter D50 : 0.095 μm
Silica: trade name: SFP-20M, manufacturer: Denka Co., Ltd., particle diameter D50 : 0.4 μm
＜埋め込み性の評価＞
各電磁波シールドフィルムについて以下の方法で埋め込み性を評価した。
図３は、電磁波シールドフィルムの埋め込み性の評価方法を模式的に示す平面図である。
図３に示すように、試験用プリント配線板４０にプレス機を用いて温度：１７０℃、時間：３０分、圧力：２～３ＭＰａの条件で、電磁波シールドフィルム１を貼付した。
試験用プリント配線板４０は、ベースフィルム（図示せず）の上に設けられた互いに間隔をおいて平行に延びる２本の銅箔パターン４１と、銅箔パターンを覆うポリイミドからなるカバーレイ（厚さ：２５μｍ）４２とを有しており、カバーレイ４２には、直径が１．０ｍｍ又は０．８ｍｍのグランド接続部を模擬した開口部４３を設けた。 <Evaluation of embeddability>
The embeddability of each electromagnetic wave shielding film was evaluated by the following method.
FIG. 3 is a plan view schematically showing a method for evaluating embeddability of an electromagnetic wave shielding film.
As shown in FIG. 3, the electromagnetic wave shielding film 1 was attached to the test printed wiring board 40 using a press under conditions of temperature: 170° C., time: 30 minutes, and pressure: 2 to 3 MPa.
The test printed wiring board 40 consists of two copper foil patterns 41 extending parallel to each other with a space therebetween provided on a base film (not shown), and a coverlay (thickness) made of polyimide covering the copper foil patterns. The coverlay 42 had an opening 43 simulating a ground connection of 1.0 mm or 0.8 mm in diameter.
試験用プリント配線板４０に形成された２本の銅箔パターン４１間の電気抵抗値を抵抗計５１により以下の時期に測定した。
初期、２６５℃に１秒間さらされる疑似リフロー操作を５回行った後、温度：８５℃及び湿度：８５％で２５０時間経った後、温度：８５℃及び湿度：８５％で５００時間経った後、温度：８５℃及び湿度：８５％で７５０時間経った後、温度：８５℃及び湿度：８５％で１０００時間経った後、及び、温度：８５℃及び湿度：８５％で３０００時間経った後。
結果を表２に示す。 The electrical resistance value between the two copper foil patterns 41 formed on the test printed wiring board 40 was measured by the resistance meter 51 at the following times.
Initial, after 5 times of pseudo-reflow operation exposed to 265°C for 1 second, after 250 hours at temperature: 85°C and humidity: 85%, after 500 hours at temperature: 85°C and humidity: 85% , after 750 hours at 85°C and 85% humidity, after 1000 hours at 85°C and 85% humidity, and after 3000 hours at 85°C and 85% humidity. .
Table 2 shows the results.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
＜耐屈曲性の評価＞
各電磁波シールドフィルムを保護層が外側になるように、かつ、曲率半径Ｒが０．２ｍｍとなるように湾曲させ、３秒間保持した後、湾曲させた部分の保護層にクラックが生じるか否かを、顕微鏡を用いて１００倍に拡大して目視にて確認した。
結果を表３に示す。評価基準は以下の通りである。
〇：クラックが生じなかった。
△：１００μｍ未満の大きさのクラックが１個のみ生じた。
×：１００μｍ以上のクラックが、複数個生じた。 <Evaluation of bending resistance>
After bending each electromagnetic wave shielding film so that the protective layer is on the outside and the radius of curvature R is 0.2 mm, and held for 3 seconds, whether cracks occur in the curved part of the protective layer. was visually confirmed using a microscope at a magnification of 100 times.
Table 3 shows the results. Evaluation criteria are as follows.
O: No crack occurred.
Δ: Only one crack having a size of less than 100 μm was generated.
x: A plurality of cracks of 100 μm or more were generated.
表３に示すように、実施例１～４に係る電磁波シールドフィルムは、保護層にクラックが生じない、又は、１００μｍ未満のクラックが１個のみ生じただけであった。
これに対して、比較例に係る電磁波シールドフィルムのうち、耐屈曲性の評価で×となったものは、プリント配線板への貼付後に、シールド性低下への影響が顕著に現れるおそれのある１ｍｍ以上のクラックが複数個発生していた。 As shown in Table 3, the electromagnetic wave shielding films according to Examples 1 to 4 had no cracks in the protective layer, or had only one crack of less than 100 μm.
On the other hand, among the electromagnetic wave shielding films according to the comparative examples, those that were evaluated as x in the evaluation of bending resistance had a 1 mm thickness that may significantly affect the reduction in shielding properties after being attached to the printed wiring board. A plurality of cracks as described above were generated.
＜プレス後の破断評価＞
各電磁波シールドフィルムについて以下の方法でプレス後の破断を評価した。
図４は、電磁波シールドフィルムのプレス後の破断評価の評価方法を模式的に示す断面図である。
図４に示すように凹形状の段差を有するベースフィルム６２と、凹形状の段差を挟むように平行にベースフィルム６２の表面に形成された１対の銅箔パターン６１とを有する試験用高段差プリント配線板６０を準備した。なお、凹形状の段差の幅は１０ｍｍであり、凹形状の段差の深さは３００μｍであった。
電磁波シールドフィルム１の等方導電性接着剤層２０が、試験用高段差プリント配線板６０に接触するように配置した後、プレス機を用いて温度：１７０℃、時間：３０分、圧力：１．５～２．０ＭＰａの条件で、電磁波シールドフィルムを試験用高段差プリント配線板６０に貼付した。
試験用高段差プリント配線板６０に形成された２本の銅箔パターン６１間の電気抵抗値を抵抗計５１により測定した。
結果を表３に示す。 <Break evaluation after pressing>
Each electromagnetic wave shielding film was evaluated for breakage after pressing by the following method.
FIG. 4 is a cross-sectional view schematically showing an evaluation method for evaluating breakage after pressing of an electromagnetic wave shielding film.
As shown in FIG. 4, a high level difference for testing having a base film 62 having a concave level difference and a pair of copper foil patterns 61 formed in parallel on the surface of the base film 62 so as to sandwich the concave level difference. A printed wiring board 60 was prepared. The width of the concave step was 10 mm, and the depth of the concave step was 300 μm.
After placing the isotropic conductive adhesive layer 20 of the electromagnetic wave shielding film 1 in contact with the test high-step printed wiring board 60, a press was used at a temperature of 170°C, a time of 30 minutes, and a pressure of 1. The electromagnetic wave shielding film was attached to the test high-stepped printed wiring board 60 under the condition of 5 to 2.0 MPa.
The electrical resistance value between the two copper foil patterns 61 formed on the test high-stepped printed wiring board 60 was measured by the resistance meter 51 .
Table 3 shows the results.
＜仮止め性の評価＞
各電磁波シールドフィルムをポリイミドからなる絶縁層に１２５℃、０．５ＭＰａ、５ｍｉｎの条件で熱プレスし、仮止めを行った。
その後、電磁波シールドフィルムのみを持ち上げ、電磁波シールドフィルムが絶縁層から剥がれるかどうかを目視で確認した。
結果を表３に示す。評価基準は以下の通りである。
〇：電磁波シールドフィルムに剥がれが生じなかった。
△：電磁波シールドフィルムがわずかに剥がれた。
×：電磁波シールドフィルムが剥がれた。 <Evaluation of Temporary Fixability>
Each electromagnetic wave shielding film was hot-pressed on an insulating layer made of polyimide under the conditions of 125° C., 0.5 MPa, and 5 minutes for temporary fixing.
After that, only the electromagnetic wave shielding film was lifted, and it was visually confirmed whether the electromagnetic wave shielding film was peeled off from the insulating layer.
Table 3 shows the results. Evaluation criteria are as follows.
◯: No peeling occurred in the electromagnetic wave shielding film.
Δ: The electromagnetic wave shielding film was slightly peeled off.
x: The electromagnetic wave shielding film was peeled off.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
表２及び表３に示すように、本発明の電磁波シールドフィルムは、埋め込み性の評価、耐屈曲性の評価及びプレス後の破断評価が良好であった。これらの結果より、本発明の電磁波シールドフィルムは、高段差を有する基板に配置しても破損しにくいことが判明した。すなわち、本発明の電磁波シールドフィルムは高段差対応性が高い。
また、表３に示すように、本発明の電磁波シールドフィルムは仮止め性の評価にも優れていることが判明した。 As shown in Tables 2 and 3, the electromagnetic wave shielding film of the present invention was excellent in evaluation of embeddability, evaluation of bending resistance, and evaluation of breakage after pressing. From these results, it was found that the electromagnetic wave shielding film of the present invention is less likely to be damaged even when placed on a substrate having a high level difference. That is, the electromagnetic wave shielding film of the present invention is highly adaptable to high steps.
In addition, as shown in Table 3, it was found that the electromagnetic wave shielding film of the present invention was also excellent in evaluation of temporary fixing properties.
１　電磁波シールドフィルム
１０　保護層
２０　等方導電性接着剤層
３０　高段差プリント配線板
３１　ベースフィルム
３２　プリント回路
３２ａ　グランド回路
３３　カバーレイ
３３ａ　開口部
３４　段差
３４ａ　角部
３４ｂ　凹部
４０　試験用プリント配線板
４１　銅箔パターン
４２　カバーレイ
４３　開口部
５１　抵抗計
６０　試験用高段差プリント配線板
６１　銅箔パターン
６２　ベースフィルム

  Reference Signs List 1 electromagnetic wave shielding film 10 protective layer 20 isotropic conductive adhesive layer 30 high stepped printed wiring board 31 base film 32 printed circuit 32a ground circuit 33 coverlay 33a opening 34 step 34a corner 34b recess 40 test printed wiring board 41 Copper foil pattern 42 Coverlay 43 Opening 51 Resistance meter 60 High stepped printed wiring board for test 61 Copper foil pattern 62 Base film

Claims (10)

  1. 保護層と、
    前記保護層に積層された等方導電性接着剤層とを備え、
    前記保護層は、保護層用フィラーを含み、
    前記等方導電性接着剤層は、樹脂成分と、導電性フィラーと、非導電性フィラーとを含み、
    前記非導電性フィラーの重量に対する前記導電性フィラーの重量の割合（導電性フィラーの重量／非導電性フィラーの重量）は、１５．０～２３．０であり、
    前記保護層用フィラーの重量に対する前記導電性フィラー及び前記非導電性フィラーの合計重量の割合（（導電性フィラーの重量＋非導電性フィラーの重量）／保護層用フィラーの重量）は、１．９～２．２であることを特徴とする電磁波シールドフィルム。     a protective layer;
    An isotropic conductive adhesive layer laminated on the protective layer,
    The protective layer contains a protective layer filler,
    The isotropic conductive adhesive layer contains a resin component, a conductive filler, and a non-conductive filler,
    The ratio of the weight of the conductive filler to the weight of the non-conductive filler (weight of conductive filler/weight of non-conductive filler) is 15.0 to 23.0,
    The ratio of the total weight of the conductive filler and the non-conductive filler to the weight of the protective layer filler ((weight of conductive filler+weight of non-conductive filler)/weight of protective layer filler) is 1. 9 to 2.2, an electromagnetic wave shielding film.
  2. 前記導電性フィラーは、銀粉、銅粉、ニッケル粉、ハンダ粉、アルミニウム粉、銅粉に銀めっきを施した銀コート銅粉、高分子微粒子やガラスビーズ等を金属で被覆した微粒子からなる群から選択される少なくとも１種である請求項１に記載の電磁波シールドフィルム。 The conductive filler is selected from the group consisting of silver powder, copper powder, nickel powder, solder powder, aluminum powder, silver-coated copper powder obtained by plating copper powder with silver, and fine particles obtained by coating polymer fine particles, glass beads, or the like with metal. 2. The electromagnetic wave shielding film according to claim 1, which is at least one selected.
  3. 前記非導電性フィラーは、ポリリン酸塩、ホスフィン酸金属塩及びシリカからなる群から選択される少なくとも１種である請求項１又は２に記載の電磁波シールドフィルム。 3. The electromagnetic wave shielding film according to claim 1, wherein the non-conductive filler is at least one selected from the group consisting of polyphosphate, metal phosphinate and silica.
  4. 前記保護層用フィラーは、シリカ、クレー、石膏、カーボンフィラー、炭酸カルシウム、硫酸バリウム、酸化アルミナ、酸化ベリリウム、酸化亜鉛、炭化珪素及び窒化珪素からなる群から選択される少なくとも１種である請求項１～３のいずれかに記載の電磁波シールドフィルム。 The protective layer filler is at least one selected from the group consisting of silica, clay, gypsum, carbon filler, calcium carbonate, barium sulfate, alumina oxide, beryllium oxide, zinc oxide, silicon carbide and silicon nitride. 4. The electromagnetic wave shielding film according to any one of 1 to 3.
  5. 前記導電性フィラーの粒子径Ｄ５０は、２０μｍ以下である請求項１～４のいずれかに記載の電磁波シールドフィルム。 The electromagnetic wave shielding film according to any one of claims 1 to 4, wherein the conductive filler has a particle diameter D50 of 20 µm or less.
  6. 前記非導電性フィラーの粒子径Ｄ５０は、２０μｍ以下である請求項１～５のいずれかに記載の電磁波シールドフィルム。 The electromagnetic wave shielding film according to any one of claims 1 to 5, wherein the non-conductive filler has a particle diameter D50 of 20 µm or less.
  7. 前記保護層用フィラーの粒子径Ｄ５０は、２０μｍ以下である請求項１～６のいずれかに記載の電磁波シールドフィルム。 7. The electromagnetic wave shielding film according to claim 1, wherein the protective layer filler has a particle diameter D50 of 20 μm or less.
  8. 前記等方導電性接着剤層に占める前記導電性フィラー及び前記非導電性フィラーの合計重量割合は、６６～７１重量％である請求項１～７のいずれかに記載の電磁波シールドフィルム。 The electromagnetic wave shielding film according to any one of claims 1 to 7, wherein the total weight ratio of said conductive filler and said non-conductive filler in said isotropic conductive adhesive layer is 66 to 71% by weight.
  9. 前記保護層に占める前記保護層用フィラーの重量割合は、２０～４０重量％である請求項１～８のいずれかに記載の電磁波シールドフィルム。 The electromagnetic wave shielding film according to any one of claims 1 to 8, wherein the weight ratio of the protective layer filler in the protective layer is 20 to 40% by weight.
  10. 前記保護層と、前記等方導電性接着剤層とは直接接触している請求項１～９のいずれかに記載の電磁波シールドフィルム。

          The electromagnetic wave shielding film according to any one of claims 1 to 9, wherein the protective layer and the isotropic conductive adhesive layer are in direct contact.
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JP2019046871A (en) * 2017-08-30 2019-03-22 タツタ電線株式会社 Electromagnetic wave shield film, shield printed wiring board, and method for manufacturing shield printed wiring board
JP2019163419A (en) * 2018-03-20 2019-09-26 タツタ電線株式会社 Conductive adhesive layer
WO2020009229A1 (en) * 2018-07-06 2020-01-09 タツタ電線株式会社 Adhesive film for printed wiring board
JP2020007484A (en) * 2018-07-11 2020-01-16 タツタ電線株式会社 Conductive adhesive

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JP2015206992A (en) * 2014-04-11 2015-11-19 太陽インキ製造株式会社 Photosensitive resin composition, dry film, cured product, and printed wiring board
JP2019046871A (en) * 2017-08-30 2019-03-22 タツタ電線株式会社 Electromagnetic wave shield film, shield printed wiring board, and method for manufacturing shield printed wiring board
JP2019163419A (en) * 2018-03-20 2019-09-26 タツタ電線株式会社 Conductive adhesive layer
WO2020009229A1 (en) * 2018-07-06 2020-01-09 タツタ電線株式会社 Adhesive film for printed wiring board
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