WO2023090334A1 - Film de blindage contre les ondes électromagnétiques - Google Patents

Film de blindage contre les ondes électromagnétiques 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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Prior art keywords
electromagnetic wave
shielding film
wave shielding
filler
protective layer
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PCT/JP2022/042463
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English (en)
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/fr

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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

La présente invention concerne un film de blindage contre les ondes électromagnétiques qui n'est pas facilement endommagé même lorsqu'il est placé sur un substrat à hauteur élevée. Le film de blindage contre les ondes électromagnétiques comprend une couche de protection et une couche adhésive conductrice isotrope stratifiée sur la couche de protection, la couche de protection contenant une charge de couche de protection, la couche adhésive conductrice isotrope contenant un composant de résine, une charge conductrice, et une charge non conductrice, le rapport du poids de la charge conductrice au poids de la charge non conductrice (le poids de la charge conductrice/le poids de la charge non conductrice) étant de 15,0 à 23,0, et le rapport du poids total de la charge conductrice et de la charge non conductrice au poids de la charge de couche protectrice ((le poids de la charge conductrice + le poids de la charge non conductrice)/le poids de la charge de couche de protection) étant de 1,9 à 2,2.
PCT/JP2022/042463 2021-11-16 2022-11-16 Film de blindage contre les ondes électromagnétiques WO2023090334A1 (fr)

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JP2021-186489 2021-11-16

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015206992A (ja) * 2014-04-11 2015-11-19 太陽インキ製造株式会社 感光性樹脂組成物、ドライフィルム、硬化物およびプリント配線板
JP2019046871A (ja) * 2017-08-30 2019-03-22 タツタ電線株式会社 電磁波シールドフィルム、シールドプリント配線板、及び、シールドプリント配線板の製造方法
JP2019163419A (ja) * 2018-03-20 2019-09-26 タツタ電線株式会社 導電性接着剤層
WO2020009229A1 (fr) * 2018-07-06 2020-01-09 タツタ電線株式会社 Film adhésif pour carte de circuit imprimé
JP2020007484A (ja) * 2018-07-11 2020-01-16 タツタ電線株式会社 導電性接着剤

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015206992A (ja) * 2014-04-11 2015-11-19 太陽インキ製造株式会社 感光性樹脂組成物、ドライフィルム、硬化物およびプリント配線板
JP2019046871A (ja) * 2017-08-30 2019-03-22 タツタ電線株式会社 電磁波シールドフィルム、シールドプリント配線板、及び、シールドプリント配線板の製造方法
JP2019163419A (ja) * 2018-03-20 2019-09-26 タツタ電線株式会社 導電性接着剤層
WO2020009229A1 (fr) * 2018-07-06 2020-01-09 タツタ電線株式会社 Film adhésif pour carte de circuit imprimé
JP2020007484A (ja) * 2018-07-11 2020-01-16 タツタ電線株式会社 導電性接着剤

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