WO2012164925A1 - Electrically conductive sheet and process for producing same, and electronic component - Google Patents

Electrically conductive sheet and process for producing same, and electronic component Download PDF

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Publication number
WO2012164925A1
WO2012164925A1 PCT/JP2012/003541 JP2012003541W WO2012164925A1 WO 2012164925 A1 WO2012164925 A1 WO 2012164925A1 JP 2012003541 W JP2012003541 W JP 2012003541W WO 2012164925 A1 WO2012164925 A1 WO 2012164925A1
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WO
WIPO (PCT)
Prior art keywords
conductive
conductive layer
layer
fine particles
dendritic
Prior art date
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PCT/JP2012/003541
Other languages
French (fr)
Japanese (ja)
Inventor
祐司 西山
冨永　浩史
邦広 古川
英宣 小林
和規 松戸
孝洋 松沢
晟 瞿
Original Assignee
東洋インキＳｃホールディングス株式会社
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First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=47258797&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=WO2012164925(A1) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by 東洋インキＳｃホールディングス株式会社 filed Critical 東洋インキＳｃホールディングス株式会社
Priority to KR1020137033789A priority Critical patent/KR101846474B1/en
Priority to KR1020187009342A priority patent/KR101931274B1/en
Priority to CN201280026529.XA priority patent/CN103597551B/en
Priority to JP2013517880A priority patent/JP6064903B2/en
Publication of WO2012164925A1 publication Critical patent/WO2012164925A1/en

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    • 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
    • H05K9/0073—Shielding materials
    • H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
    • H05K9/0083—Electromagnetic shielding materials, e.g. EMI, RFI shielding comprising electro-conductive non-fibrous particles embedded in an electrically insulating supporting structure, e.g. powder, flakes, whiskers
    • 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
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/16—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by features of a layer formed of particles, e.g. chips, powder or granules
    • 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
    • B32B7/04—Interconnection of layers
    • B32B7/06—Interconnection of layers permitting easy separation
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K7/00—Use of ingredients characterised by shape
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/10—Adhesives in the form of films or foils without carriers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J9/00—Adhesives characterised by their physical nature or the effects produced, e.g. glue sticks
    • C09J9/02—Electrically-conducting adhesives
    • 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
    • B32B2264/00—Composition or properties of particles which form a particulate layer or are present as additives
    • B32B2264/10—Inorganic particles
    • B32B2264/105—Metal
    • 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
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/30—Properties of the layers or laminate having particular thermal properties
    • B32B2307/302—Conductive
    • 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
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/30—Properties of the layers or laminate having particular thermal properties
    • B32B2307/304—Insulating
    • 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
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/748—Releasability
    • 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
    • B32B2457/00—Electrical equipment
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2203/00—Applications of adhesives in processes or use of adhesives in the form of films or foils
    • C09J2203/326—Applications of adhesives in processes or use of adhesives in the form of films or foils for bonding electronic components such as wafers, chips or semiconductors
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2301/00—Additional features of adhesives in the form of films or foils
    • C09J2301/40—Additional features of adhesives in the form of films or foils characterized by the presence of essential components
    • C09J2301/408—Additional features of adhesives in the form of films or foils characterized by the presence of essential components additives as essential feature of the adhesive layer

Definitions

  • the present invention relates to a conductive sheet that can be used by being attached to an adherend such as a printed wiring board, and a method for manufacturing the same. Moreover, it is related with the electronic component containing the above-mentioned electroconductive sheet.
  • Patent Document 1 discloses a thermosetting conductive adhesive sheet having a three-layer structure in which a conductive layer is sandwiched between adhesive layers made of a thermosetting adhesive.
  • the conductive layer constituting this sheet has a protruding portion raised in the surface direction.
  • the protruding portion of the conductive layer is in direct electrical contact with the adherend through the adhesive layer by thermocompression bonding the adhesive layer to the adherend. Thereby, it functions as a conductive adhesive sheet.
  • Patent Document 2 discloses a conductive adhesive film containing a thermoplastic resin having a glass transition temperature of ⁇ 10 ° C. or higher and 50 ° C. or lower, and silver powder.
  • the silver powder it is usually described that at least two kinds of silver powder, spherical, fine sphere and flake are used in combination.
  • Patent Document 3 discloses an electromagnetic wave shielding adhesive film comprising a polyurethane polyurea resin, an epoxy resin having two or more epoxy groups, and a conductive filler.
  • the conductive adhesive sheet disclosed in Patent Document 1 employs a structure in which a conductive layer made of a metal foil such as copper, iron, and aluminum is sandwiched between adhesive layers, the thickness of the printed wiring board is reduced. There is a problem that it is not suitable for thinning. Further, since the metal foil has low flexibility, it has been difficult to use it for a flexible printed wiring board in which a conductive adhesive sheet is repeatedly bent.
  • the conductive adhesive film disclosed in Patent Document 2 is not suitable for use in a high temperature environment because the heat resistance of the thermoplastic resin is low.
  • the present invention has been made in view of the above-mentioned background, and the object of the present invention is to minimize the seepage of the conductive layer in a hot press process in which a conductive sheet is adhered to an adherend such as a printed wiring board. It is to provide a conductive sheet having good processability, a method for producing the same, and an electronic component.
  • the conductive sheet according to the present invention comprises a conductive layer containing at least the thermosetting resin (A) and dendritic conductive fine particles (B), and the thickness of the conductive layer is (i) 150 ° C., The thickness after heat pressing under the conditions of 2 MPa for 30 minutes, when the thickness of the conductive layer before heat pressing is 100, is in the range of 30 to 95, and (ii) the dendritic conductivity the average particle diameter D 90 of fine particles (B) is 0.5 times or more the thickness of the conductive layer, those in the range of 3 times or less, at least one of met, the dendritic conductive fine particles (B) And having an average particle diameter D 50 of 3 ⁇ m or more and 50 ⁇ m or less, and containing the dendritic conductive fine particles (B) in the conductive layer in a range of 50 wt% or more and 90 wt% or less. It is.
  • the electronic component according to the present invention is one in which the conductive sheet of the above aspect is stuck.
  • the method for producing a conductive sheet according to the present invention comprises a conductive resin composition comprising dendritic conductive fine particles (B) having an average particle diameter D 50 of 3 ⁇ m or more and 50 ⁇ m or less, and a thermosetting resin (A). Then, it is applied to a peelable sheet to form a conductive layer containing the dendritic conductive fine particles (B) in a range of 50 wt% or more and 90 wt% or less, and the conductive layer is 2.5 MPa or more and 50 MPa. It includes a step of applying the following pressure.
  • a conductive layer containing a large amount of voids is formed before hot pressing, so that, for example, heat flowing when a conductive sheet is hot pressed on a printed wiring board. It became possible to absorb a plastic resin etc. in the said space
  • electronic parts such as a printed wiring board using the conductive sheet have a good yield due to a significant reduction in the number of defective products derived from seepage. Furthermore, the short circuit of the circuit of electronic parts, such as a printed wiring board, and ion migration could be reduced significantly.
  • a conductive sheet having good workability capable of reducing the seepage of the conductive layer to a minimum in the hot press step of sticking the conductive sheet to an adherend such as a printed wiring board, and its production
  • an adherend such as a printed wiring board
  • FIG. 2B is a cross-sectional view taken along the line IIB-IIB in FIG. 2A.
  • FIG. 2C is a cross-sectional view taken along the line IIC-IIC in FIG. 2A.
  • It is explanatory drawing of the circuit for measuring the connection resistance value A and is a schematic plan view of the flexible printed wiring board after heat-pressing a conductive sheet and a stainless steel plate.
  • FIG. 2D is a sectional view taken along the line IIE-IIE in FIG. 2D.
  • FIG. 2D is a cross-sectional view taken along the line IIF-IIF in FIG. 2D.
  • FIG. 3B is a cross-sectional view taken along the line IIIB-IIIB in FIG. 3A.
  • 3C is a cross-sectional view taken along the line IIIC-IIIC in FIG. 3A. It is explanatory drawing of the circuit for measuring the connection resistance value B, and the typical top view after laminating
  • FIG. 3D is a cross-sectional view taken along the line IIIE-IIIE of FIG. 3D.
  • FIG. 3D is a cross-sectional view taken along the line IIIF-IIIF of FIG. 3D.
  • any number A to any number B means a range larger than the numbers A and A but smaller than the numbers B and B.
  • the conductive sheet of the present invention has at least a conductive layer.
  • the conductive sheet may be composed of a single conductive layer, or may be a laminate of a plurality of conductive layers.
  • a layer other than the conductive layer for example, a support layer, an insulating layer, a protective layer, an adhesive layer
  • the electroconductive sheet as used in this specification does not need to have an electroconductive characteristic in the whole sheet, and should just have an electroconductive characteristic in an electroconductive layer at least.
  • the conductive characteristics of the conductive layer can be appropriately set according to the application and needs, and are not particularly limited.
  • the example comprised from one conductive layer is demonstrated as one embodiment of an electroconductive sheet.
  • the conductive layer of the conductive sheet according to the first embodiment includes a thermosetting resin (A) and dendritic conductive fine particles (B) as essential components.
  • A thermosetting resin
  • B dendritic conductive fine particles
  • the thickness after the heat press is 30 or more when the thickness of the conductive layer before the heat press is 100, The range is 95 or less.
  • the “conductive layer before hot pressing” refers to a conductive layer immediately before being attached to an adherend such as a printed wiring board.
  • the adherend is a general object to which the conductive sheet is attached, and examples thereof include a printed wiring board and a flexible board.
  • the thickness of the conductive layer after hot pressing under the above conditions of the conductive layer of the conductive sheet is more preferably 40 or more, and further preferably 45 or more. Further, the thickness of the conductive layer after the hot pressing is more preferably 90 or less, and further preferably 85 or less. Particularly preferred is the range of 60-80. When the thickness after hot pressing is greater than 95, it is assumed that there are few voids in the conductive layer before hot pressing, so there is little change in thickness before and after hot pressing, and the thermosetting resin (A ) May increase.
  • the conductive layer is assumed to have too many voids, so the thickness change before and after the hot pressing is large, and the voids remain even with the hot press, achieving the desired conductivity. It tends to be difficult.
  • the “bleed out” as used in this specification includes bleeding of a low molecular weight component and protrusion of a conductive layer flowing.
  • the void formed by using dendritic conductive fine particles (B) in the conductive layer is filled by hot pressing under conditions of a temperature of 150 ° C., a time of 30 minutes, and a pressure of 2 MPa. It is something that can be done.
  • the conditions at the time of adhering the electroconductive sheet of 1st Embodiment to adherends, such as a printed wiring board explain the example performed on the said heat press conditions, a different heat press process is employ
  • a sheet may be formed. For example, heating conditions, pressing conditions, and the like can be adjusted according to the type of thermoplastic resin used.
  • the conductive sheet of the first embodiment is laminated so that the conductive layer side of the conductive sheet of the first embodiment is in contact with an adherend such as a printed wiring board, and the adherend is subjected to the heating press step.
  • a conductive sheet can be attached to the substrate.
  • the thermoplastic resin since the thermoplastic resin is contained, adhesiveness with a to-be-adhered body can be kept favorable.
  • the adhesive layer different from a conductive layer is provided in a conductive sheet according to a use and needs, and the aspect which joins an adhesive layer and a to-be-adhered body It is good.
  • thermosetting resin (A) used in the first embodiment is not particularly limited as long as it does not depart from the gist of the present invention, but acrylic, phenolic, epoxy, urethane, melamine, alkyd resins, etc. Is preferred. Furthermore, when the adhesive is bonded in the hot press step and is used after being attached like a flexible printed wiring board, an acrylic resin and a urethane resin having both heat resistance and flexibility are more preferable. In addition, a thermosetting resin (A) may use one type, or may mix and use two or more types.
  • a curing agent in combination with the thermosetting resin (A).
  • the curing agent a known compound corresponding to the functional group of the resin to be used can be used.
  • the resin contains a carboxyl group
  • a resin contains a hydroxyl group, an isocyanate hardening
  • FIG. 1A shows an SEM image of an example of dendritic conductive fine particles (B) suitable for the conductive layer of the first embodiment.
  • the dendritic shape is generally called a dendritic shape and means a shape like a tree branch.
  • the material of the dendritic conductive fine particles (B) is a conductive metal such as gold, silver, copper, nickel, zinc or iron or an alloy thereof, a conductive organic compound such as polyaniline, polythiophene, or polyacetylene, or a conductive compound composed of these. Can be exemplified.
  • conductive fine particles in which a metal, an organic compound, or an inorganic compound is used as a nucleus and the surface of the nucleus is covered with a conductive material are also preferable examples.
  • the conductive fine particles having a conductive coating layer particles having a coating layer formed on the surface with respect to a core serving as a core are preferable examples.
  • the core include metals such as copper, nickel, and cadmium, conductive organic compounds such as polyaniline, polythiophene, and polyacetylene, or ordinary non-conductive organic compounds.
  • money, silver, copper is mentioned.
  • more preferable examples include conductive fine particles in which a coating layer is formed of silver with copper as a nucleus.
  • a dendritic electroconductive fine particle (B) may use a single type, and may mix and use multiple types.
  • the proportion of the coating layer in the conductive fine particles having a conductive coating layer is preferably 1% by weight to 40% by weight, more preferably 5% by weight to 20% by weight in 100% by weight of the dendritic conductive fine particles (B). .
  • the thickness of the conductive sheet changes before and after the heating press because the voids are likely to exist in the conductive layer mainly due to the presence of the bulky dendritic conductive fine particles (B), and the thermosetting resin (A) is changed by the heating press. It is speculated that this is due to the flow and filling the gap.
  • the voids of the dendritic conductive fine particles (B) are more easily affected by the relationship between the average particle diameter D 50 and the average particle diameter D 90 of the dendritic conductive fine particles (B) used. And a thickness change becomes large, so that there are many space
  • the dendritic conductive fine particles (B) preferably have an average particle diameter D 50 of 3 ⁇ m to 50 ⁇ m and an average particle diameter D 90 of 1.5 to 5 times the average particle diameter D 50 .
  • the average particle size D 50 is more preferably 3 ⁇ m to 40 ⁇ m, and further preferably 5 ⁇ m to 25 ⁇ m.
  • Mean By particle diameter D 50 is equal to or greater than 3 [mu] m, easily can voids in the conductive layer, it can be reduced exudation. On the other hand, the average particle diameter D 50 is 50 ⁇ m or less, it becomes easy to form the conductive layer of the appropriate thickness.
  • the average particle diameter D 90 of the dendrite conductive fine particles (B) is preferably from 1.5 to 5 times the average particle diameter D 50, 2-fold to 3.5-fold and more preferably.
  • the value of the average particle diameter D 90 tends to depend on the average particle diameter of the average particle diameter D 50 , but is preferably 4.5 ⁇ m to 250 ⁇ m.
  • the average particle diameter D 90 is not more than 5 times the average particle diameter D 50 , the width of the particle diameter distribution is not too wide, and the dendritic conductive fine particles (B) in the conductive layer are appropriately filled. Tend to be. Furthermore, the presence of huge dendritic particles makes it difficult for the huge dendritic particles to protrude from the conductive layer after heat pressing.
  • the dendrite-like conductive fine particles (B) preferably have a tap density (hereinafter also referred to as “TD”) of 0.8 g / cm 3 to 2.5 g / cm 3 .
  • TD tap density
  • the conductive fine particles can be more densely packed in the conductive layer.
  • the TD is 2.5 g / cm 3 or less, the conductive fine particles in the conductive layer are less likely to be overfilled and the film thickness before and after the heating press tends to be maintained at a large state. It is possible to reduce the ejection more.
  • the dendritic conductive fine particles (B) preferably have an apparent density (hereinafter also referred to as “AD”) of 0.4 g / cm 3 to 1.5 g / cm 3 .
  • AD apparent density
  • the conductive fine particles can be more densely packed in the conductive layer.
  • the TD is 1.5 g / cm 3 or less, the conductive fine particles in the conductive layer are less likely to be overfilled and the film thickness before and after the heating press tends to be maintained at a large state. It is possible to reduce the ejection more.
  • the dendritic conductive fine particles (B) By making the values of the apparent density AD and the tap density TD of the dendritic conductive fine particles (B) appropriate, voids can be formed more appropriately in the conductive layer. That is, the dendritic conductive fine particles (B) preferably have an AD / TD ratio (AD / TD) of 0.3 to 0.9. By setting AD / TD to 0.3 or more, the numerical values of AD and TD become more appropriate, and the change in film thickness after hot pressing tends not to be too large. On the other hand, by making AD / TD 0.9 or less, the numerical values of AD and TD become more appropriate, and the change in film thickness after hot pressing tends not to be too small.
  • the proportion of the dendritic conductive fine particles (B) used in the conductive layer is preferably 50% to 90% by weight and more preferably 60% to 80% by weight in 100% by weight of the conductive layer.
  • the amount used is 50% by weight or more, desired conductivity tends to be easily obtained.
  • the amount is 90% by weight or less, the amount of resin for forming a sheet tends to be easily secured.
  • the dendrite-like conductive fine particles (B) are shaped like tree branches as compared with spherical conductive fine particles or flaky conductive fine particles (see FIG. 1B). Easy to form. Therefore, when a conductive layer is formed using dendritic conductive fine particles (B), voids are likely to occur. By using the dendritic conductive fine particles (B), it is possible to stain in the horizontal direction compared to the case where conductive sheets using spherical conductive particles or flaky conductive fine particles as the main component are heated and pressed under the same conditions. It is possible to reduce the ejection more.
  • thermosetting resin (A) and the dendritic conductive fine particles (B) can be included.
  • additives can be included.
  • silane coupling agents, antioxidants, pigments, dyes, tackifying resins, plasticizers, ultraviolet absorbers, antifoaming agents, leveling regulators, fillers, flame retardants and the like can be included.
  • a conductive resin composition (C) is prepared by mixing at least a thermosetting resin (A) and dendritic conductive fine particles (B).
  • the mixing method is not particularly limited, but preferred examples include a method using a mixer, a dissolver, a Hoover Mahler, a three-roll mill, a sand mill, and the like.
  • the conductive resin composition (C) for example, it is coated on a release sheet to form a conductive layer coating.
  • the coating method is not particularly limited, and a conventionally known method can be used without limitation. For example, gravure coating, kiss coating, die coating, lip coating, comma coating, blade coating, roll coating, knife coating, spray coating, bar coating, spin coating, dip coating, etc. A film is formed.
  • the thickness of the conductive layer before being hot-pressed can be appropriately set according to the use, but is preferably 5 ⁇ m to 100 ⁇ m.
  • the thickness is a value measured according to JISB7503 (dial gauge).
  • the film thickness of the conductive sheet of the first embodiment after hot pressing is preferably 0.25 to 10 times the average particle diameter D 50 of the dendritic conductive fine particles (B), preferably 0.5 to 5 times is more preferable.
  • the application of the conductive sheet of the first embodiment is not particularly limited, and can be used for all applications in which a conductive sheet is desired to be used.
  • it can be used for the purpose of attaching an electromagnetic wave shield to a printed wiring board, or for grounding a circuit formed on the printed wiring board.
  • it can be used by being attached to various electronic devices such as home appliances such as a microwave oven.
  • the conductive sheet of the first embodiment even if only one layer is used instead of a three-layer structure, an adhesive force to an adherend can be expressed by using a thermoplastic resin. it can. As a result, there is an excellent merit that it can be used for thin film applications. Moreover, since the electroconductive layer which uses a thermoplastic resin and dendritic electroconductive fine particles as an essential component is used without using metal foil like patent document 1, it is excellent in flexibility. Therefore, it can be suitably applied to flexible printed wiring boards and the like. Further, by using dendritic conductive fine particles as the conductive fine particles, voids or the like can be formed in the conductive layer, and the seepage during heat pressing can be absorbed by the voids.
  • the seepage of the conductive layer can be minimized.
  • the use of dendritic conductive fine particles can effectively suppress the seepage of the conductive layer.
  • the conductive sheet of the present invention it can be suitably used as an application used under severe conditions such as high temperature and high humidity.
  • the conductive sheet according to the second embodiment is a conductive sheet with an insulating layer in which an insulating layer and the conductive layer of the first embodiment are stacked.
  • the insulating layer used in the conductive sheet of the second embodiment is not particularly limited as long as it does not depart from the spirit of the present invention.
  • the raw material of an insulating layer is not specifically limited, For example, it is preferable to use resin which has insulation, such as the thermosetting resin (A) which can be used with a conductive layer.
  • resin which has insulation such as the thermosetting resin (A) which can be used with a conductive layer.
  • plastic films such as polyester, a polycarbonate, a polyimide, polyphenylene sulfide, can also be used.
  • the insulating layer contains a silane coupling agent, an antioxidant, a pigment, a dye, a tackifier resin, a plasticizer, an ultraviolet absorber, an antifoaming agent, a leveling adjusting agent, a filler, a flame retardant and the like as necessary. You can also.
  • the use of the conductive sheet of the second embodiment is not particularly limited, for example, the conductive layer side can be attached to the outer main surface of the printed wiring board and used as an electromagnetic wave shielding film.
  • a well-known method can be used for the formation method of the insulating layer of the electroconductive sheet of 2nd Embodiment, and the lamination
  • a conductive layer can be formed on a previously formed insulating layer, or can be formed on the insulating layer by the same manufacturing method as the conductive layer described in the first embodiment.
  • the thickness of the insulating layer varies depending on the application, but is preferably 5 ⁇ m to 50 ⁇ m, for example.
  • the conductive layer is the same as that of the first embodiment, the same effect as that of the first embodiment can be obtained. Moreover, by using a laminated body with an insulating layer, it is possible to increase the mechanical strength of the conductive sheet or to impart insulating characteristics to the surface.
  • the layer for laminating the conductive layer is not particularly limited, and layers having various functions are used depending on the purpose.
  • stacked optical films such as a support layer, a semiconductor layer, a protective film, and an antireflection film, may be sufficient.
  • the method for manufacturing a conductive sheet according to the third embodiment is different from the method for manufacturing a conductive sheet according to the first embodiment in that a press process is included before the hot pressing described in the first embodiment.
  • a press process is included before the hot pressing described in the first embodiment.
  • the conductive sheet of the third embodiment is formed after applying and forming a conductive layer, and before performing a heat press when adhering to the adherend, a pressurizing step (hereinafter referred to as adherend and conductive).
  • adherend and conductive a pressurizing step
  • adherend and conductive a pressurizing step
  • it is manufactured by performing a “pre-pressurization step”.
  • the pre-pressurization step can be appropriately changed depending on the application, it is preferable to apply a pressure of 2.5 MPa to 50 MPa (25 kg / cm 2 to 510 kg / cm 2.
  • the temperature does not exclude heating. It is not intended to induce deformation or breakage of the dendritic conductive fine particles (B) and to promote the flow of the thermoplastic resin. Therefore, it is preferable that the heating is not performed or the temperature is not higher than the temperature that promotes the flow of the thermoplastic resin. .
  • pressure is applied to the conductive sheet in advance to deform the dendritic conductive fine particles (B) or fold the dendritic particles, thereby dendritic conductive fine particles (B)
  • the contact between each other becomes dense, and the conductive properties of the conductive layer can be further improved.
  • a method for applying pressure to the conductive sheet there is a method using a flat plate press, a roll press or the like. Among these, a roll press machine that can easily increase the pressure (increase the linear pressure) is preferable.
  • rolls having different surface hardnesses such as a metal roll and a resin roll can be used.
  • the conductive layer of the third embodiment performs a pre-pressurization step.
  • the thickness after the heat pressing under the above conditions needs to be in the range of 30 or more and 95 or less when the thickness of the conductive layer before the heat pressing is 100. That is, the thickness of the conductive layer before joining to the adherend after the pre-pressurization step is heated under the above conditions (150 ° C., 2 MPa, heated for 30 minutes).
  • the change needs to be included in the above range (a range of 30 or more and 95 or less when the thickness of the conductive layer is 100).
  • a film thickness may change in a pre-pressurization process. Even if the film thickness changes in the pre-pressurization step, the adherend and the conductive sheet can be removed if there is a gap for absorbing the movement of the thermoplastic resin composition or the bleed low molecular weight component. This is because even if heat-pressing at the time of joining, the seepage of the conductive layer can be effectively suppressed.
  • the conductive sheet having the same conductive layer as in the first embodiment since the same effect as in the first embodiment can be obtained.
  • the conductive layer is pressed in advance and the dendritic conductive fine particles (B) are crushed before the printed wiring board and the conductive sheet are heated and pressed, there is a merit that the conductive characteristics can be effectively extracted. is there.
  • the pre-pressurization step of the third embodiment can be suitably added.
  • the conductive sheet is a conductive sheet with an insulating layer
  • the timing of performing the pre-pressurization step is not limited, but it is more preferable to perform the pre-pressurization step before laminating the insulating layer.
  • the pre-pressurization process is performed on the conductive layer, the surface of the conductive layer becomes smoother.
  • the thickness accuracy of the insulating layer is improved. It becomes easy to obtain characteristics.
  • the conductive sheet according to the fourth embodiment includes a single conductive layer.
  • the conductive layer of the conductive sheet according to the fourth embodiment includes a thermosetting resin (A) and dendritic conductive fine particles (B) as essential components, and dendritic conductive fine particles (B the average particle diameter D 90 of) is intended for a film thickness of the conductive layer is in the range of 0.5 to 3 times.
  • the thickness of the conductive layer specified in the first embodiment is 150 ° C., 2 MPa, and the thickness of the conductive layer after 30 minutes is 30 minutes, the thickness of the conductive layer before the hot press is 100. It is not always necessary to be in the range of 30 or more and 95 or less. This is for a film thickness of the conductive layer, by an average particle diameter D 90 of the dendrite conductive fine particles (B) to 3 times or less, the tip of the fine particles, not easily protrude from the conductive layer when applying the heat press Because it becomes a tendency. Further, the average particle diameter D 90 by more than 0.5 times, because the gap in the conductive layer is less likely excessively occur.
  • the thickness of the conductive layer before hot pressing is 100 Further, it is more preferable to satisfy the condition of being in the range of 30 to 95.
  • the conductive sheet of the fourth embodiment is laminated so that the conductive layer side of the conductive sheet of the fourth embodiment is in contact with an adherend such as a printed wiring board, and is subjected to the heat press step described in the first embodiment.
  • a conductive sheet can be stuck on a to-be-adhered body.
  • the electroconductive sheet of 4th Embodiment since the thermoplastic resin is contained in the electroconductive layer, adhesiveness with a to-be-adhered body can be maintained favorable.
  • the conditions of a heat press can be arbitrarily set according to the use and needs of a conductive layer (for example, according to the electroconductive characteristic calculated
  • the adherend and the conductive sheet may be joined via an adhesive layer, for example, without performing the heat press step.
  • the method through the adhesive layer is not particularly limited.
  • an adhesive layer different from the conductive layer is provided on the conductive sheet, or an adhesive layer is provided on the adherend side and the adhesive layer is attached via the adhesive layer. The method of joining the body is mentioned.
  • thermoplastic resin (A) constituting the conductive layer are as described in the first embodiment.
  • thermoplastic resin (A) for the conductive layer it is preferable to use a curing agent in combination with the thermoplastic resin (A) for the conductive layer. Examples of the curing agent are also as described in the first embodiment.
  • dendritic conductive fine particles (B) those described in the first embodiment can be suitably applied.
  • the dendritic conductive fine particles (B) preferably have an average particle diameter D 50 of 3 ⁇ m to 50 ⁇ m and an average particle diameter D 90 of 1.5 to 5 times the average particle diameter D 50 .
  • the average particle size D 50 is more preferably 3 ⁇ m to 40 ⁇ m, and further preferably 5 ⁇ m to 25 ⁇ m.
  • Mean By particle diameter D 50 is equal to or greater than 3 [mu] m, easily can voids in the conductive layer, it can be reduced exudation. On the other hand, the average particle diameter D 50 is 50 ⁇ m or less, it becomes easy to form the conductive layer of the appropriate thickness.
  • the average particle diameter D 90 of the dendrite conductive fine particles (B) is preferably from 1.5 to 5 times the average particle diameter D 50, 2-fold to 3.5-fold and more preferably.
  • the value of the average particle diameter D 90 tends to depend on the average particle diameter of the average particle diameter D 50 , but is preferably 4.5 ⁇ m to 250 ⁇ m. The reason is as described in the first embodiment.
  • the dendrite-like conductive fine particles (B) preferably have a tap density (hereinafter also referred to as “TD”) of 0.8 g / cm 3 to 2.5 g / cm 3 .
  • the dendritic conductive fine particles (B) preferably have an apparent density (hereinafter also referred to as “AD”) of 0.4 g / cm 3 to 1.5 g / cm 3 .
  • AD apparent density
  • the dendritic conductive fine particles (B) have an AD / TD ratio (AD / TD) of 0.3 to 0.9.
  • the thickness of the conductive sheet of the fourth embodiment is not particularly limited, but is preferably 5 ⁇ m to 100 ⁇ m, and more preferably 10 ⁇ m to 50 ⁇ m.
  • the thickness is a value measured according to JISB7503 (dial gauge).
  • JISB7503 dial gauge
  • the proportion of the dendritic conductive fine particles (B) used in the conductive layer is preferably 50% to 90% by weight and more preferably 60% to 80% by weight in 100% by weight of the conductive layer.
  • the reason is as described in the first embodiment.
  • an additive can be added as necessary, and examples thereof include the additives described in the first embodiment.
  • the manufacturing method of an electroconductive sheet is as having described in 1st Embodiment.
  • the same effect as in the first embodiment can be obtained.
  • a dendrite-like conductive fine particle (B) in the conductive layer having an average particle diameter D 90 in the range of 0.5 to 3 times the thickness of the conductive layer is used as the thickness of the conductive layer.
  • the conductive sheet of the fifth embodiment is a laminate of the insulating layer and the conductive layer of the fourth embodiment.
  • the electromagnetic wave shielding film may be laminated with other layers (for example, a protective layer and an adhesive layer) other than the insulating layer and the conductive layer.
  • the material used for the insulating layer is not particularly limited, but preferred examples include those described in the second embodiment.
  • silane coupling agents, antioxidants, pigments, dyes, tackifier resins, plasticizers, ultraviolet absorbers, antifoaming agents, leveling regulators, fillers, flame retardants, etc., as necessary Can also be included.
  • the method for forming the insulating layer is as described in the second embodiment.
  • the thickness of the insulating layer is preferably 50 to 200 when the thickness of the conductive layer is 100. By making the thickness within the above range, it becomes easy to balance the physical properties of the electromagnetic wave shielding film.
  • the conductive layer of the conductive sheet of the fifth embodiment does not necessarily need to undergo a heating process, and the film thickness of the conductive layer indicates a film thickness when actually used, and before the heating process. Even after the heating process.
  • the adherend to which the electromagnetic wave shielding film can be attached is not particularly limited, and for example, a flexible printed wiring board that is repeatedly bent can be given as a representative example.
  • the present invention can be applied to various substrates such as rigid printed wiring boards, home appliances such as microwave ovens that require electromagnetic shielding, general electronic devices, and general members that want to shield electromagnetic waves.
  • the average particle diameter D 50 and the average particle diameter D 90 were measured using a Microtrac MT3300 manufactured by Nikkiso Co., Ltd.
  • the apparent density was determined by an apparent density test method for metal powder defined in JIS Z 2504: 2000.
  • the tap density was determined by JIS Z 2512: Metal powder-tap density measurement method.
  • a conductive sheet was prepared using the materials shown in Table 1A as the dendritic conductive fine particles, and using a urethane resin (manufactured by Toyochem) as the thermosetting resin.
  • the ratio of dendritic conductive fine particles (B) to thermosetting resin (A) was 250 parts by weight of dendritic conductive fine particles (B) with respect to 100 parts by weight of resin solids.
  • Examples 6 to 10 Using a urethane resin (manufactured by Toyochem Co., Ltd.) as an insulating layer on one side of the conductive sheets obtained in Examples 1 to 5, coating and drying to a dry film thickness of 10 ⁇ m, an insulating layer having a total thickness of 20 ⁇ m An attached conductive sheet was obtained.
  • a urethane resin manufactured by Toyochem Co., Ltd.
  • Example 11 The surface of the conductive sheet obtained in Example 2 was pre-pressurized using a roll press so that a pressure of 3 MPa was applied. Then, a conductive sheet with an insulating layer having a total thickness of 20 ⁇ m is obtained by applying and drying urethane resin (manufactured by Toyochem) as an insulating layer on the pre-pressurized conductive sheet surface so that the dry film thickness becomes 10 ⁇ m. It was.
  • urethane resin manufactured by Toyochem
  • Example 12 and 13 A conductive sheet with an insulating layer was obtained in the same manner as in Example 11 except that the prepressurizing pressure was changed to 10 MPa and 40 MPa, respectively.
  • the evaluation criteria are as follows. ⁇ : The amount of exudation of the conductive sheet is less than 0.01 mm. ⁇ : The amount of exudation of the conductive sheet is 0.01 mm or more and less than 0.05 mm. ⁇ : The amount of exudation of the conductive sheet is 0.05 mm or more.
  • connection resistance value A Samples having a width of 20 mm and a length of 50 mm were prepared for the conductive sheets of Examples 1 to 5 and Comparative Examples 1 and 2, and the connection resistance value A was measured using a separately prepared flexible printed wiring board. Specifically, as shown in FIGS. 2A to 2F, a circuit 2 made of copper foil having a thickness of 18 ⁇ m and not electrically connected is formed on a polyimide film 1 having a thickness of 12.5 ⁇ m. A flexible printed wiring board was prepared by laminating a cover film 3 having a through hole 4 having a thickness of 37.5 ⁇ m and a diameter of 0.8 mm, with an adhesive.
  • a conductive sheet 5 is placed on the cover film 3, and a 200 ⁇ m thick stainless steel plate 6 whose surface is treated with 0.1 ⁇ m thick nickel is placed on the conductive sheet 5 at 150 ° C., Heat pressing was performed for 30 minutes under the condition of 2.0 MPa. Thereafter, the resistance value in the vertical direction between the circuit 2 and the stainless steel plate 6 was measured using a four-point probe of “Lorester GP” manufactured by Mitsubishi Chemical Corporation.
  • the evaluation criteria are as follows. ⁇ : Less than 200 m ⁇ ⁇ : 200 m ⁇ or more, less than 500 m ⁇ x: 500 m ⁇ or more
  • connection resistance value B For the conductive sheets with insulating layers of Examples 6 to 13 and Comparative Examples 3 and 4, samples having a width of 20 mm and a length of 50 mm were prepared, and the connection resistance value B was measured using a separately prepared flexible printed wiring board. Specifically, as shown in FIGS. 3A to 3F, circuits 2A and 2B made of copper foil having a thickness of 18 ⁇ m and not electrically connected are formed on a polyimide film 1 having a thickness of 12.5 ⁇ m. A flexible printed wiring board was prepared in which a cover film 3 having a through hole 4 having a thickness of 37.5 ⁇ m and a diameter of 0.8 mm was laminated on the circuit 2A.
  • a conductive sheet 5 is placed on the cover film 3, and a 200 ⁇ m thick insulating layer 7 whose surface is treated with 0.1 ⁇ m thick nickel is placed on the conductive sheet 5 at 150 ° C. Heating and pressing was performed for 30 minutes under the condition of 2.0 MPa, and the resistance value between the circuit 2A and the circuit 2B was measured using a four-point probe of “Lorestar GP” manufactured by Mitsubishi Chemical Corporation.
  • the evaluation criteria are as follows. ⁇ : Less than 300 m ⁇ ⁇ : 300 m ⁇ or more, less than 500 m ⁇ x: 500 m ⁇ or more
  • the evaluation criteria are as follows. ⁇ : 3000 times or more ⁇ : 2500 times or more and less than 3000 times ⁇ : less than 2500 times
  • an average particle diameter D 50 was prepared a conductive layer by a silver 13 .mu.m.
  • the thermosetting resin a urethane resin (manufactured by Toyochem) is used, and the ratio of the dendritic conductive fine particles (B) to the thermosetting resin is 250 parts by weight of the dendritic conductive fine particles with respect to 100 parts by weight of the resin. Then, it was coated on a polyethylene terephthalate film having a surface of 100 ⁇ m peel-treated so that the dry film thickness was 10 ⁇ m using a bar coater, and dried at 100 ° C.
  • a conductive layer for 3 minutes to obtain a conductive layer.
  • an urethane resin manufactured by Toyochem Co., Ltd.
  • coating and drying were performed so that the dry film thickness was 15 ⁇ m, and an electromagnetic wave shielding film having an insulating layer with a total thickness of 25 ⁇ m was obtained. .
  • Examples 15 to 17 were carried out in the same manner as in Example 1 except that the conductive fine particles, the average particle diameter D 90, and the average particle diameter D 50 were replaced with the raw materials shown in Table 2A to obtain an electromagnetic wave shielding film. .
  • a conductive layer was prepared using the materials shown in Table 2A as the dendritic conductive fine particles (B) and a urethane resin (manufactured by Toyochem) as the thermosetting resin (A).
  • the ratio of the dendritic conductive fine particles (B) to the thermosetting resin (A) is such that the dendritic conductive fine particles are 250 parts by weight with respect to 100 parts by weight of the resin, and the thickness is 100 ⁇ m so that the dry film thickness is 10 ⁇ m.
  • coating was performed using a bar coater and dried at 100 ° C. for 3 minutes to obtain a conductive sheet.
  • an electromagnetic field film having an insulating layer with a total thickness of 18 ⁇ m is obtained. It was.
  • thermosetting resin a urethane resin (manufactured by Toyochem) is used, and the ratio of the dendritic conductive fine particles (B) to the thermosetting resin is 250 parts by weight of the dendritic conductive fine particles with respect to 100 parts by weight of the resin. Then, it was coated on a polyethylene terephthalate film having a 100 ⁇ m thick surface peel-treated so that the dry film thickness was 10 ⁇ m, and dried at 100 ° C. for 3 minutes to obtain a conductive sheet.
  • the thermosetting resin a urethane resin (manufactured by Toyochem) is used, and the ratio of the dendritic conductive fine particles (B) to the thermosetting resin is 250 parts by weight of the dendritic conductive fine particles with respect to 100 parts by weight of the resin. Then, it was coated on a polyethylene terephthalate film having a 100 ⁇ m thick surface peel-treated so that the dry film thickness was 10 ⁇ m, and dried at 100 °
  • a urethane resin (manufactured by Toyochem Co., Ltd.) was used as an insulating layer on one side of the conductive sheet, and a dry film thickness of 25 ⁇ m was provided to obtain an electromagnetic wave shielding film having an insulating layer with a total thickness of 35 ⁇ m.
  • Example 20 The surface of the conductive sheet obtained in Example 18 was pre-pressurized using a roll press so that a pressure of 3 MPa was applied. After that, a conductive sheet with an insulating layer having a total thickness of 20 ⁇ m is formed by applying and drying urethane resin (manufactured by Toyochem) as an insulating layer on the pre-pressurized conductive sheet surface so that the dry film thickness becomes 10 ⁇ m. Obtained.
  • urethane resin manufactured by Toyochem
  • Example 21 and 22 A conductive sheet with an insulating layer was obtained in the same manner as in Example 20 except that the prepressurizing pressure was changed to 10 MPa and 40 MPa, respectively.
  • dendrite silver dendrite copper powder, flaky silver, and spherical silver in Tables 2A and 2B, those manufactured by Fukuda Metal Foil Powder Industry Co., Ltd. were used.
  • the dendrite silver-coated copper powders in Tables 2A and 2B use dendrite copper powders manufactured by Fukuda Metal Foil Powder Industry Co., Ltd., and are coated with silver under the following conditions. A 10% by weight dendrite silver-coated copper powder was obtained.
  • the electromagnetic shielding films of the example of 6 mm width and 120 mm length and the comparative example were evaluated by the same method as the refractive evaluation described in Examples 1 to 13 and Comparative Examples 1 to 4. Evaluation criteria were the same as those described above. It is as follows.
  • ⁇ Insulation reliability> The electromagnetic wave shielding films of Examples 11 to 16 and Comparative Examples 11 to 15 having a width of 100 mm and a length of 100 mm were prepared and subjected to heat press treatment at 150 ° C. for 30 minutes and 2.0 MPa. After 1 minute when contact was made for 1 minute under the condition that the printing voltage was 100V, using HIPE-UP (MCP-HT450) surface resistance tester TYPE URS made by Mitsubishi Chemical Co., Ltd. The insulation reliability was evaluated. The evaluation criteria are as follows.
  • the average particle diameter D 90 of the dendritic conductive fine particles is specified within the range of 0.5 to 3 times the film thickness of the conductive layer, so that the conductive fine particles of the conventional shape are obtained. It can be seen that there is less seepage of the conductive layer in the lateral direction after hot pressing. Moreover, it was confirmed that it showed excellent flexibility and high insulation reliability.
  • An electromagnetic wave shielding film having at least an insulating layer and a conductive layer,
  • the conductive layer contains at least a thermosetting resin (A) and dendritic conductive fine particles (B), and the average particle diameter D90 of the dendritic conductive fine particles (B) is 0.5 to 0.5 with respect to the thickness of the conductive layer.
  • An electromagnetic wave shielding film characterized by being in a range of 3 times.
  • the dendritic conductive fine particles (B) include a nucleus containing copper and a silver coating layer, Item 4.
  • (Appendix 5) 5.
  • the conductive sheet according to the present invention can reduce the seepage of the conductive layer to a minimum in a process such as a heating process, the conductive sheet is attached to all adherends such as printed wiring boards and flexible printed boards. It can be suitably applied to applications that are used at least. In particular, it is particularly effective for sticking to the use of electronic parts where the bleeding of the conductive sheet is a problem.
  • the conductive sheet according to the present invention can be used by being laminated with an insulating layer, a support layer, an adhesive layer, a film having another function, or the like.

Abstract

Provided are: an electrically conductive sheet having good processability, whereby it becomes possible to minimize the leaching of an electrically conductive layer in a hot-pressing step for adhering the electrically conductive sheet onto an object of interest, such as a printed wiring board; a process for producing the electrically conductive sheet; and others. This electrically conductive sheet involves an electrically conductive layer comprising at least a heat-curable resin (A) and dendritic electrically conductive microparticles (B). The thickness of the electrically conductive layer fulfills the following requirement (i) and/or (ii): (i) the thickness of the electrically conductive layer becomes 30-95 after being hot-pressed under the conditions of 150ºC, 2 MPa and 30 minutes when the thickness of the electrically conductive layer before the hot-pressing is defined as 100; and (ii) the average particle diameter (D90) of the dendritic electrically conductive microparticles (B) becomes 0.5-3 times the thickness of the electrically conductive layer. The dendritic electrically conductive microparticles (B) have an average particle diameter (D50) of 3-50 μm inclusive and are contained in an amount of 50-90 wt% inclusive in the electrically conductive layer.

Description

導電性シート及びその製造方法、並びに電子部品Conductive sheet, method for manufacturing the same, and electronic component
　本発明は、例えば、プリント配線板等の被着体に貼着して使用できる導電性シート及びその製造方法に関する。また、前述の導電性シートを含む電子部品に関する。 The present invention relates to a conductive sheet that can be used by being attached to an adherend such as a printed wiring board, and a method for manufacturing the same. Moreover, it is related with the electronic component containing the above-mentioned electroconductive sheet.
　近年の電子機器の軽薄短小化に伴い、プリント配線板の小型化に加えて、フレキシブルプリント配線板が多く使用されるようになってきている。これら配線板には、高機能化を実現すべく、種々の導電性シートが使用されている。 In recent years, as electronic devices have become lighter, thinner, and smaller, flexible printed wiring boards are increasingly used in addition to downsizing printed wiring boards. For these wiring boards, various conductive sheets are used in order to realize high functionality.
　例えば、特許文献１では、導電層が熱硬化性接着剤からなる接着層に挟持された３層構造の熱硬化型導電性接着シートが開示されている。このシートを構成する導電層は、表面方向に隆起した突起部を有する。この導電層の突起部は、被着体に接着層を加熱圧着することによって接着層を貫通して被着体と電気的に直接接触する。これにより、導電性接着性シートとして機能するようになっている。 For example, Patent Document 1 discloses a thermosetting conductive adhesive sheet having a three-layer structure in which a conductive layer is sandwiched between adhesive layers made of a thermosetting adhesive. The conductive layer constituting this sheet has a protruding portion raised in the surface direction. The protruding portion of the conductive layer is in direct electrical contact with the adherend through the adhesive layer by thermocompression bonding the adhesive layer to the adherend. Thereby, it functions as a conductive adhesive sheet.
　また、特許文献２においては、ガラス転移温度が－１０℃以上、５０℃以下の熱可塑性樹脂、及び銀粉を含有する導電性接着フィルムが開示されている。銀粉としては、通常、アドマイズ銀粉、球状、微細球状、フレーク状の中から少なくとも２種以上を組み合わせて用いることが記載されている。 Patent Document 2 discloses a conductive adhesive film containing a thermoplastic resin having a glass transition temperature of −10 ° C. or higher and 50 ° C. or lower, and silver powder. As the silver powder, it is usually described that at least two kinds of silver powder, spherical, fine sphere and flake are used in combination.
　特許文献３においては、ポリウレタンポリウレア樹脂と、２個以上のエポキシ基を有するエポキシ樹脂と、導電性フィラーとを含有してなる電磁波シールド性接着フィルムが開示されている。 Patent Document 3 discloses an electromagnetic wave shielding adhesive film comprising a polyurethane polyurea resin, an epoxy resin having two or more epoxy groups, and a conductive filler.
特開２００２－９７４２４号公報JP 2002-97424 A 特開２００４－２８８５６０号公報JP 2004-288560 A ＷＯ２００６／０８８１２７号公報WO2006 / 088127
　しかしながら、特許文献１で開示されている導電性接着シートは、銅、鉄、アルミなどの金属箔からなる導電層を接着剤層によって挟持する構造を採用しているので、プリント配線板の厚みを薄くする場合には適当でないという問題があった。また、金属箔は屈曲性が弱いので、導電性接着シートを繰り返し屈曲するフレキシブルプリント配線板に使用することは困難であった。 However, since the conductive adhesive sheet disclosed in Patent Document 1 employs a structure in which a conductive layer made of a metal foil such as copper, iron, and aluminum is sandwiched between adhesive layers, the thickness of the printed wiring board is reduced. There is a problem that it is not suitable for thinning. Further, since the metal foil has low flexibility, it has been difficult to use it for a flexible printed wiring board in which a conductive adhesive sheet is repeatedly bent.
　また、特許文献２で開示されている導電性接着フィルムは、熱可塑性樹脂の耐熱性が低いため、高温環境下での使用に適していなかった。 In addition, the conductive adhesive film disclosed in Patent Document 2 is not suitable for use in a high temperature environment because the heat resistance of the thermoplastic resin is low.
　また、導電性シートをプリント配線板等に貼り付ける場合、導電層が染み出すと電子デバイスの電気特性に大きな影響を与える。このため、市場からは、導電性シートの染み出しに対する要求が厳しく、特許文献２や特許文献３などの従来の導電性のシートに対して、導電層の染み出しに対する更なる改良が求められていた。 Also, when a conductive sheet is attached to a printed wiring board or the like, if the conductive layer oozes out, the electrical characteristics of the electronic device are greatly affected. For this reason, the demand for the seepage of the conductive sheet is severe from the market, and further improvements to the seepage of the conductive layer are required for the conventional conductive sheets such as Patent Document 2 and Patent Document 3. It was.
　本発明は上記背景に鑑みてなされたものであり、その目的とするところは、プリント配線板等の被着体に導電性シートを貼着する加熱プレス工程において、導電層の染み出しを最小限に低減できる加工性が良好な導電性シート及びその製造方法、並びに電子部品の提供することである。 The present invention has been made in view of the above-mentioned background, and the object of the present invention is to minimize the seepage of the conductive layer in a hot press process in which a conductive sheet is adhered to an adherend such as a printed wiring board. It is to provide a conductive sheet having good processability, a method for producing the same, and an electronic component.
　本発明に係る導電性シートは、熱硬化性樹脂（Ａ）と、デンドライト状導電性微粒子（Ｂ）と、を少なくとも含む導電層を具備し、前記導電層の厚みが、（ｉ）１５０℃、２ＭＰａ、３０分間の条件で加熱プレスした後の厚みが、加熱プレス前の当該導電層の厚みを１００としたときに３０以上、９５以下の範囲になるもの、及び（ｉｉ）前記デンドライト状導電性微粒子（Ｂ）の平均粒子径Ｄ９０が、当該導電層の厚みに対して０．５倍以上、３倍以下の範囲になるもの、の少なくとも一方を満たし、前記デンドライト状導電性微粒子（Ｂ）の平均粒子径Ｄ５０が３μｍ以上、５０μｍ以下のものであって、かつ、前記デンドライト状導電性微粒子（Ｂ）を前記導電層中に５０重量％以上、９０重量％以下の範囲で含有するものである。 The conductive sheet according to the present invention comprises a conductive layer containing at least the thermosetting resin (A) and dendritic conductive fine particles (B), and the thickness of the conductive layer is (i) 150 ° C., The thickness after heat pressing under the conditions of 2 MPa for 30 minutes, when the thickness of the conductive layer before heat pressing is 100, is in the range of 30 to 95, and (ii) the dendritic conductivity the average particle diameter D 90 of fine particles (B) is 0.5 times or more the thickness of the conductive layer, those in the range of 3 times or less, at least one of met, the dendritic conductive fine particles (B) And having an average particle diameter D 50 of 3 μm or more and 50 μm or less, and containing the dendritic conductive fine particles (B) in the conductive layer in a range of 50 wt% or more and 90 wt% or less. It is.
　本発明に係る電子部品は、上記態様の導電性シートが貼着せしめられたものである。 The electronic component according to the present invention is one in which the conductive sheet of the above aspect is stuck.
　本発明に係る導電性シートの製造方法は、平均粒子径Ｄ５０が３μｍ以上、５０μｍ以下のデンドライト状導電性微粒子（Ｂ）と、熱硬化性樹脂（Ａ）とを含む導電性樹脂組成物を、剥離性シートに塗工して、前記デンドライト状導電性微粒子（Ｂ）を５０重量％以上、９０重量％以下の範囲で含有する導電層を形成し、前記導電層に２．５ＭＰａ以上、５０ＭＰａ以下の圧力を加える工程を含むものである。 The method for producing a conductive sheet according to the present invention comprises a conductive resin composition comprising dendritic conductive fine particles (B) having an average particle diameter D 50 of 3 μm or more and 50 μm or less, and a thermosetting resin (A). Then, it is applied to a peelable sheet to form a conductive layer containing the dendritic conductive fine particles (B) in a range of 50 wt% or more and 90 wt% or less, and the conductive layer is 2.5 MPa or more and 50 MPa. It includes a step of applying the following pressure.
　本発明によれば、デンドライト状導電性微粒子を用いることにより、加熱プレス前に空隙を多く含む導電層を形成しているので、例えば、プリント配線板に導電性シートを加熱プレスする時に流動する熱可塑性樹脂等を当該空隙で吸収することが可能となった。これにより導電層の染み出しを防止し、加工性を改善できた。その結果、当該導電性シートを使用したプリント配線板等の電子部品は、染み出し由来の不良品が大幅に減少し歩留まりが良好である。さらにはプリント配線板等の電子部品の回路のショートや、イオンマイグレーションを大幅に低減できた。 According to the present invention, by using the dendritic conductive fine particles, a conductive layer containing a large amount of voids is formed before hot pressing, so that, for example, heat flowing when a conductive sheet is hot pressed on a printed wiring board. It became possible to absorb a plastic resin etc. in the said space | gap. This prevented the conductive layer from seeping out and improved the workability. As a result, electronic parts such as a printed wiring board using the conductive sheet have a good yield due to a significant reduction in the number of defective products derived from seepage. Furthermore, the short circuit of the circuit of electronic parts, such as a printed wiring board, and ion migration could be reduced significantly.
　本発明によれば、プリント配線板等の被着体に導電性シートを貼着する加熱プレス工程において、導電層の染み出しを最小限に低減できる加工性が良好な導電性シート、及びその製造方法、並びに電子部品を提供できるという優れた効果がある。 According to the present invention, a conductive sheet having good workability capable of reducing the seepage of the conductive layer to a minimum in the hot press step of sticking the conductive sheet to an adherend such as a printed wiring board, and its production There is an excellent effect that a method and an electronic component can be provided.
デンドライト状導電性微粒子の一例を示すＳＥＭ像。The SEM image which shows an example of a dendrite-like electroconductive fine particle. フレーク状導電性微粒子の一例を示すＳＥＭ像。The SEM image which shows an example of flake shaped electroconductive fine particles. 接続抵抗値Ａを測定するための回路の説明図であり、カバーフィルムが積層されたフレキシブルプリント配線板の模式的平面図。It is explanatory drawing of the circuit for measuring the connection resistance value A, and is a schematic plan view of the flexible printed wiring board with which the cover film was laminated | stacked. 図２ＡのＩＩＢ－ＩＩＢ切断部断面図。FIG. 2B is a cross-sectional view taken along the line IIB-IIB in FIG. 2A. 図２ＡのＩＩＣ－ＩＩＣ切断部断面図。FIG. 2C is a cross-sectional view taken along the line IIC-IIC in FIG. 2A. 接続抵抗値Ａを測定するための回路の説明図であり、導電性シートとステンレス板を重ね、加熱プレスした後のフレキシブルプリント配線板の模式的平面図。It is explanatory drawing of the circuit for measuring the connection resistance value A, and is a schematic plan view of the flexible printed wiring board after heat-pressing a conductive sheet and a stainless steel plate. 図２ＤのＩＩＥ－ＩＩＥ切断部断面図。FIG. 2D is a sectional view taken along the line IIE-IIE in FIG. 2D. 図２ＤのＩＩＦ－ＩＩＦ切断部断面図。FIG. 2D is a cross-sectional view taken along the line IIF-IIF in FIG. 2D. 接続抵抗値Ｂを測定するための回路の説明図であり、カバーフィルムが積層されたフレキシブルプリント配線板の模式的平面図。It is explanatory drawing of the circuit for measuring the connection resistance value B, and is a schematic plan view of the flexible printed wiring board with which the cover film was laminated | stacked. 図３ＡのＩＩＩＢ－ＩＩＩＢ切断部断面図。FIG. 3B is a cross-sectional view taken along the line IIIB-IIIB in FIG. 3A. 図３ＡのＩＩＩＣ－ＩＩＩＣ切断部断面図。3C is a cross-sectional view taken along the line IIIC-IIIC in FIG. 3A. 接続抵抗値Ｂを測定するための回路の説明図であり、導電性シートとステンレス板を重ね、加熱プレスした後の模式的平面図。It is explanatory drawing of the circuit for measuring the connection resistance value B, and the typical top view after laminating | stacking a conductive sheet and a stainless steel plate and carrying out the heat press. 図３ＤのＩＩＩＥ－ＩＩＩＥ切断部断面図。FIG. 3D is a cross-sectional view taken along the line IIIE-IIIE of FIG. 3D. 図３ＤのＩＩＩＦ－ＩＩＩＦ切断部断面図。FIG. 3D is a cross-sectional view taken along the line IIIF-IIIF of FIG. 3D.
　以下、本発明の実施の形態を、詳細に説明する。なお、本発明の趣旨に合致する限り、他の実施形態も本発明の範疇に属し得る。また、以下の実施形態は、互いに好適に組み合わせることができる。また、本明細書において「任意の数Ａ～任意の数Ｂ」なる記載は、数Ａ及び数Ａより大きい範囲であって、数Ｂ及び数Ｂより小さい範囲を意味する。 Hereinafter, embodiments of the present invention will be described in detail. In addition, as long as it agree | coincides with the meaning of this invention, other embodiment can also belong to the category of this invention. Further, the following embodiments can be suitably combined with each other. In the present specification, the description “any number A to any number B” means a range larger than the numbers A and A but smaller than the numbers B and B.
　本発明の導電性シートは、少なくとも導電層を有するものである。導電性シートは、一層の導電層からなるものでも、複数の導電層が積層されたものでもよく、また、導電層以外の層（例えば、支持層、絶縁層、保護層、接着層）などが積層されたものでもよい。なお、本明細書でいう導電性シートは、シート全体において導電特性を有する必要はなく、少なくとも導電層において導電特性を有していればよい。導電層の導電特性は、用途やニーズに応じて適宜設定することができ、特に限定されるものではない。 The conductive sheet of the present invention has at least a conductive layer. The conductive sheet may be composed of a single conductive layer, or may be a laminate of a plurality of conductive layers. In addition, a layer other than the conductive layer (for example, a support layer, an insulating layer, a protective layer, an adhesive layer) or the like may be used. It may be laminated. In addition, the electroconductive sheet as used in this specification does not need to have an electroconductive characteristic in the whole sheet, and should just have an electroconductive characteristic in an electroconductive layer at least. The conductive characteristics of the conductive layer can be appropriately set according to the application and needs, and are not particularly limited.
［第１実施形態］
　第１実施形態においては、導電性シートの一実施態様として、１層の導電層から構成される例について説明する。第１実施形態の導電性シートの導電層は、熱硬化性樹脂（Ａ）と、デンドライト状導電性微粒子（Ｂ）を必須構成として含むものである。導電層の厚みが、１５０℃、２ＭＰａ、３０分間の条件で、被着体と加熱プレスした場合に、加熱プレス前の導電層の厚みを１００としたときに加熱プレス後の厚みが３０以上、９５以下の範囲になるものである。なお、「加熱プレス前の導電層」とは、プリント配線板等の被着体に貼り付ける直前の導電層をいう。また、被着体は、導電性シートを貼り付ける対象物全般であり、例えば、プリント配線基板、フレキシブル基板等が挙げられる。 [First Embodiment]
In 1st Embodiment, the example comprised from one conductive layer is demonstrated as one embodiment of an electroconductive sheet. The conductive layer of the conductive sheet according to the first embodiment includes a thermosetting resin (A) and dendritic conductive fine particles (B) as essential components. When the thickness of the conductive layer is 150 ° C., 2 MPa, and 30 minutes press-adhered to the adherend, the thickness after the heat press is 30 or more when the thickness of the conductive layer before the heat press is 100, The range is 95 or less. The “conductive layer before hot pressing” refers to a conductive layer immediately before being attached to an adherend such as a printed wiring board. Further, the adherend is a general object to which the conductive sheet is attached, and examples thereof include a printed wiring board and a flexible board.
　導電性シートの導電層の上記条件下での加熱プレス後の導電層の厚みは、４０以上がより好ましく、４５以上であることがさらに好ましい。また、当該加熱プレス後の導電層の厚みは９０以下であることがより好ましく、８５以下であることがさらに好ましい。特に好ましくは、６０～８０の範囲である。加熱プレス後の厚みが９５より大きい場合、加熱プレス前の導電層に空隙が少ないことが想定されるため、加熱プレス前後で厚み変化が少なく、加熱プレス時に水平方向への熱硬化性樹脂（Ａ）の染み出しが大きくなる恐れがある。一方、加熱プレス後の厚みが３０より小さい場合、導電層に空隙が多すぎることが想定されるため加熱プレス前後の厚み変化が大きく、加熱プレスによっても空隙が残り、所望の導電性が達成しにくい傾向にある。なお、本明細書でいう「染み出し」とは、低分子量成分がブリードすること、及び導電層が流動したはみ出しを含むものとする。 The thickness of the conductive layer after hot pressing under the above conditions of the conductive layer of the conductive sheet is more preferably 40 or more, and further preferably 45 or more. Further, the thickness of the conductive layer after the hot pressing is more preferably 90 or less, and further preferably 85 or less. Particularly preferred is the range of 60-80. When the thickness after hot pressing is greater than 95, it is assumed that there are few voids in the conductive layer before hot pressing, so there is little change in thickness before and after hot pressing, and the thermosetting resin (A ) May increase. On the other hand, if the thickness after hot pressing is smaller than 30, the conductive layer is assumed to have too many voids, so the thickness change before and after the hot pressing is large, and the voids remain even with the hot press, achieving the desired conductivity. It tends to be difficult. In addition, the “bleed out” as used in this specification includes bleeding of a low molecular weight component and protrusion of a conductive layer flowing.
　第１実施形態の導電性シートは、導電層にデンドライト状導電性微粒子（Ｂ）を用いることによって形成させた空隙を温度１５０℃、時間３０分、圧力２ＭＰａの条件で加熱プレスすることで埋めることができるものである。なお、第１実施形態の導電性シートをプリント配線板等の被着体に貼着せしめる際の条件は、上記加熱プレス条件で行う例を説明するが、異なる加熱プレス工程を採用して導電性シートを形成してもよい。例えば、用いる熱可塑性樹脂の種類に応じて、加熱条件、プレス条件等を調整することができる。 In the conductive sheet of the first embodiment, the void formed by using dendritic conductive fine particles (B) in the conductive layer is filled by hot pressing under conditions of a temperature of 150 ° C., a time of 30 minutes, and a pressure of 2 MPa. It is something that can be done. In addition, although the conditions at the time of adhering the electroconductive sheet of 1st Embodiment to adherends, such as a printed wiring board, explain the example performed on the said heat press conditions, a different heat press process is employ | adopted and it conducts. A sheet may be formed. For example, heating conditions, pressing conditions, and the like can be adjusted according to the type of thermoplastic resin used.
　第１実施形態の導電性シートは、プリント配線板等の被着体に、第１実施形態の導電性シートの導電層側が接するように積層し、上記加熱プレス工程を経ることにより、被着体に導電性シートを貼着せしめることができる。第１実施形態の導電性シートによれば、熱可塑性樹脂を含有させているので、被着体との接着性を良好に保つことができる。なお、導電層を被着体に接合する例を述べたが、用途やニーズに応じて導電性シートに導電層とは別の接着剤層を設け、接着剤層と被着体を接合する態様としてもよい。 The conductive sheet of the first embodiment is laminated so that the conductive layer side of the conductive sheet of the first embodiment is in contact with an adherend such as a printed wiring board, and the adherend is subjected to the heating press step. A conductive sheet can be attached to the substrate. According to the electroconductive sheet of 1st Embodiment, since the thermoplastic resin is contained, adhesiveness with a to-be-adhered body can be kept favorable. In addition, although the example which joins a conductive layer to a to-be-adhered body was described, the adhesive layer different from a conductive layer is provided in a conductive sheet according to a use and needs, and the aspect which joins an adhesive layer and a to-be-adhered body It is good.
　第１実施形態において用いられる熱硬化性樹脂（Ａ）は、本発明の趣旨を逸脱しない範囲において特に限定されないが、アクリル系、フェノール系、エポキシ系、ウレタン系、メラミン系、アルキッド系などの樹脂が好ましい。さらにフレキシブルプリント配線板のように加熱プレス工程にて接着し、貼り付した後に屈曲して使用する場合には、耐熱性と屈曲性を兼ね備えたアクリル系樹脂、ウレタン系樹脂がより好ましい。なお、熱硬化性樹脂（Ａ）は、１種類を用いても、２種類以上を混合して使用してもよい。 The thermosetting resin (A) used in the first embodiment is not particularly limited as long as it does not depart from the gist of the present invention, but acrylic, phenolic, epoxy, urethane, melamine, alkyd resins, etc. Is preferred. Furthermore, when the adhesive is bonded in the hot press step and is used after being attached like a flexible printed wiring board, an acrylic resin and a urethane resin having both heat resistance and flexibility are more preferable. In addition, a thermosetting resin (A) may use one type, or may mix and use two or more types.
　導電層には、熱硬化性樹脂（Ａ）と併用して硬化剤を用いることが好ましい。硬化剤は、用いる樹脂の官能基に対応した公知の化合物を使用できる。例えば、樹脂がカルボキシル基を含有する場合はエポキシ硬化剤、アジリジン硬化剤等が好ましい。また、樹脂が水酸基を含有する場合はイソシアネート硬化剤や酸無水物基含有化合物等が好ましい。 For the conductive layer, it is preferable to use a curing agent in combination with the thermosetting resin (A). As the curing agent, a known compound corresponding to the functional group of the resin to be used can be used. For example, when the resin contains a carboxyl group, an epoxy curing agent, an aziridine curing agent and the like are preferable. Moreover, when a resin contains a hydroxyl group, an isocyanate hardening | curing agent, an acid anhydride group containing compound, etc. are preferable.
　図１Ａに、第１実施形態の導電層に好適なデンドライト状導電性微粒子（Ｂ）の一例のＳＥＭ像を示す。デンドライト状とは、一般に樹枝状ともいい、樹木の枝のような形状を意味する。デンドライト状導電性微粒子（Ｂ）の素材は、金、銀、銅、ニッケル、亜鉛または鉄などの導電性金属やその合金、ポリアニリン、ポリチオフェン、ポリアセチレンなどの導電性有機化合物、あるいはこれらを複合した導電性化合物が例示できる。または、金属や有機化合物や無機化合物を核とし、当該核の表面を導電性の素材で被覆した導電性微粒子も好ましい例として挙げられる。 FIG. 1A shows an SEM image of an example of dendritic conductive fine particles (B) suitable for the conductive layer of the first embodiment. The dendritic shape is generally called a dendritic shape and means a shape like a tree branch. The material of the dendritic conductive fine particles (B) is a conductive metal such as gold, silver, copper, nickel, zinc or iron or an alloy thereof, a conductive organic compound such as polyaniline, polythiophene, or polyacetylene, or a conductive compound composed of these. Can be exemplified. Alternatively, conductive fine particles in which a metal, an organic compound, or an inorganic compound is used as a nucleus and the surface of the nucleus is covered with a conductive material are also preferable examples.
　導電性の被覆層を有する導電性微粒子は、コアとなる核に対し、表面に被覆層が形成された粒子が好ましい例として挙げられる。核としては、銅、ニッケル、カドニウム等の金属その合金、ポリアニリン、ポリチオフェン、ポリアセチレンなどの導電性有機化合物、あるいは通常の非導電性の有機化合物などが挙げられる。また、被覆層としては、金、銀、銅などの導電性に優れる金属が挙げられる。また、銅を核として銀で被覆層を形成した導電性微粒子がより好ましい例として挙げられる。なお、デンドライト状導電性微粒子（Ｂ）は、単一種類を用いてもよいし、複数種類を混合して用いてもよい。 As the conductive fine particles having a conductive coating layer, particles having a coating layer formed on the surface with respect to a core serving as a core are preferable examples. Examples of the core include metals such as copper, nickel, and cadmium, conductive organic compounds such as polyaniline, polythiophene, and polyacetylene, or ordinary non-conductive organic compounds. Moreover, as a coating layer, the metal which is excellent in electroconductivity, such as gold | metal | money, silver, copper, is mentioned. Further, more preferable examples include conductive fine particles in which a coating layer is formed of silver with copper as a nucleus. In addition, a dendritic electroconductive fine particle (B) may use a single type, and may mix and use multiple types.
　導電性の被覆層を有する導電性微粒子における被覆層の割合は、デンドライト状導電性微粒子（Ｂ）１００重量％中、１重量％～４０重量％が好ましく、５重量％～２０重量％がより好ましい。被覆された導電性微粒子を使用することで、高価な銀の使用量の低減によるコストダウンや、銅の導電性微粒子を使用した場合の銅の酸化による導電性低下を抑制できる。 The proportion of the coating layer in the conductive fine particles having a conductive coating layer is preferably 1% by weight to 40% by weight, more preferably 5% by weight to 20% by weight in 100% by weight of the dendritic conductive fine particles (B). . By using the coated conductive fine particles, it is possible to suppress the cost reduction due to a reduction in the amount of expensive silver used, and the decrease in conductivity due to copper oxidation when copper conductive fine particles are used.
　加熱プレス前後で導電性シートの厚みが変化するのは、主として嵩高いデンドライト状導電性微粒子（Ｂ）の存在により導電層に空隙が存在しやすく、加熱プレスによりに熱硬化性樹脂（Ａ）が流動してその空隙を埋めることによるものと推測している。デンドライト状導電性微粒子（Ｂ）の空隙は、使用するデンドライト状導電性微粒子（Ｂ）の平均粒子径Ｄ５０と平均粒子径Ｄ９０の関係によって、より影響を受けやすい。そして、加熱プレス前の導電層に空隙が多いほど厚み変化が大きくなる。つまり、加熱プレス前の厚みを１００とした場合に、加熱プレス後の厚みの値が小さくなるほど導電層に空隙が多いと考えられる。 The thickness of the conductive sheet changes before and after the heating press because the voids are likely to exist in the conductive layer mainly due to the presence of the bulky dendritic conductive fine particles (B), and the thermosetting resin (A) is changed by the heating press. It is speculated that this is due to the flow and filling the gap. The voids of the dendritic conductive fine particles (B) are more easily affected by the relationship between the average particle diameter D 50 and the average particle diameter D 90 of the dendritic conductive fine particles (B) used. And a thickness change becomes large, so that there are many space | gaps in the conductive layer before a hot press. That is, when the thickness before hot pressing is 100, it is considered that the conductive layer has more voids as the thickness value after hot pressing becomes smaller.
　デンドライト状導電性微粒子（Ｂ）は、平均粒子径Ｄ５０が３μｍ～５０μｍであり、かつ平均粒子径Ｄ９０が平均粒子径Ｄ５０の１．５～５倍であることが好ましい。また、平均粒子径Ｄ５０は３μｍ～４０μｍがより好ましく、５μｍ～２５μｍがさらに好ましい。平均粒子径Ｄ５０が３μｍ以上になることで、導電層に空隙が出来やすくなり、染み出しを低減できる。一方、平均粒子径Ｄ５０が５０μｍ以下になることで、適切な厚さの導電層を形成しやすくなる。 The dendritic conductive fine particles (B) preferably have an average particle diameter D 50 of 3 μm to 50 μm and an average particle diameter D 90 of 1.5 to 5 times the average particle diameter D 50 . Further, the average particle size D 50 is more preferably 3 μm to 40 μm, and further preferably 5 μm to 25 μm. Mean By particle diameter D 50 is equal to or greater than 3 [mu] m, easily can voids in the conductive layer, it can be reduced exudation. On the other hand, the average particle diameter D 50 is 50μm or less, it becomes easy to form the conductive layer of the appropriate thickness.
　デンドライト状導電性微粒子（Ｂ）の平均粒子径Ｄ９０は、平均粒子径Ｄ５０の１．５倍～５倍が好ましく、２倍～３．５倍がより好ましい。平均粒子径Ｄ９０の値は、平均粒子径Ｄ５０の平均粒子径に依存する傾向にあるが、４．５μｍ～２５０μｍが好ましい。平均粒子径Ｄ９０が、平均粒子径Ｄ５０の１．５倍以上になることで、粒子径分布の幅が広がるため導電層中に空隙が生じやすい傾向にある。一方、平均粒子径Ｄ９０が、平均粒子径Ｄ５０の５倍以下になることで、粒子径分布の幅が広がりすぎず、導電層中のデンドライト状導電性微粒子（Ｂ）の充填が適切になる傾向にある。さらには、巨大な樹枝状粒子の存在により加熱プレス後に当該巨大な樹枝状粒子が導電層から突き出る現象が起こりにくくなる。 The average particle diameter D 90 of the dendrite conductive fine particles (B) is preferably from 1.5 to 5 times the average particle diameter D 50, 2-fold to 3.5-fold and more preferably. The value of the average particle diameter D 90 tends to depend on the average particle diameter of the average particle diameter D 50 , but is preferably 4.5 μm to 250 μm. The average particle diameter D 90 of, it becomes 1.5 times or more the average particle diameter D 50, it tends to easily occur a gap in the conductive layer in order to broadening the particle size distribution. On the other hand, when the average particle diameter D 90 is not more than 5 times the average particle diameter D 50 , the width of the particle diameter distribution is not too wide, and the dendritic conductive fine particles (B) in the conductive layer are appropriately filled. Tend to be. Furthermore, the presence of huge dendritic particles makes it difficult for the huge dendritic particles to protrude from the conductive layer after heat pressing.
　デンドライト状導電性微粒子（Ｂ）は、タップ密度（以下、「ＴＤ」ともいう）が、０．８ｇ／ｃｍ３～２．５ｇ／ｃｍ３であることが好ましい。ＴＤが０．８ｇ／ｃｍ３以上になることで、導電層中の導電性微粒子の充填をより密にできる。一方、ＴＤが２．５ｇ／ｃｍ３以下になることで、導電層中の導電性微粒子の充填が過密になりにくく、加熱プレス前後の膜厚変化が大きい状態を維持できる傾向にあるため、染み出しをより低減できる。 The dendrite-like conductive fine particles (B) preferably have a tap density (hereinafter also referred to as “TD”) of 0.8 g / cm 3 to 2.5 g / cm 3 . When the TD is 0.8 g / cm 3 or more, the conductive fine particles can be more densely packed in the conductive layer. On the other hand, when the TD is 2.5 g / cm 3 or less, the conductive fine particles in the conductive layer are less likely to be overfilled and the film thickness before and after the heating press tends to be maintained at a large state. It is possible to reduce the ejection more.
　また、デンドライト状導電性微粒子（Ｂ）は、見掛密度（以下、「ＡＤ」ともいう）が０．４ｇ／ｃｍ３～１．５ｇ／ｃｍ３であることが好ましい。ＡＤが０．４ｇ／ｃｍ３以上になることで、導電層中の導電性微粒子の充填をより密にできる。一方、ＴＤが１．５ｇ／ｃｍ３以下になることで、導電層中の導電性微粒子の充填が過密になりにくく、加熱プレス前後の膜厚変化が大きい状態を維持できる傾向にあるため、染み出しをより低減できる。 The dendritic conductive fine particles (B) preferably have an apparent density (hereinafter also referred to as “AD”) of 0.4 g / cm 3 to 1.5 g / cm 3 . When AD is 0.4 g / cm 3 or more, the conductive fine particles can be more densely packed in the conductive layer. On the other hand, since the TD is 1.5 g / cm 3 or less, the conductive fine particles in the conductive layer are less likely to be overfilled and the film thickness before and after the heating press tends to be maintained at a large state. It is possible to reduce the ejection more.
　デンドライト状導電性微粒子（Ｂ）の見掛密度ＡＤとタップ密度ＴＤの値を適切にすることで、より適切に導電層に空隙を形成できる。すなわち、デンドライト状導電性微粒子（Ｂ）は、ＡＤとＴＤの比率（ＡＤ／ＴＤ）が０．３～０．９であることがより好ましい。ＡＤ／ＴＤを０．３以上とすることで、ＡＤとＴＤの数値がより適切になり、加熱プレス後の膜厚変化が大きくなりすぎない傾向にある。一方、ＡＤ／ＴＤを０．９以下にすることで、ＡＤとＴＤの数値がより適切になり、加熱プレス後の膜厚変化が小さすぎない傾向にある。 By making the values of the apparent density AD and the tap density TD of the dendritic conductive fine particles (B) appropriate, voids can be formed more appropriately in the conductive layer. That is, the dendritic conductive fine particles (B) preferably have an AD / TD ratio (AD / TD) of 0.3 to 0.9. By setting AD / TD to 0.3 or more, the numerical values of AD and TD become more appropriate, and the change in film thickness after hot pressing tends not to be too large. On the other hand, by making AD / TD 0.9 or less, the numerical values of AD and TD become more appropriate, and the change in film thickness after hot pressing tends not to be too small.
　導電層中にデンドライト状導電性微粒子（Ｂ）を使用する割合は、導電層１００重量％中、５０重量％～９０重量％が好ましく、６０重量％～８０重量％がより好ましい。使用量が５０重量％以上になることで所望の導電性が得やすい傾向にある。一方、９０重量％以下になることでシート化するための樹脂量が確保しやすい傾向にある。 The proportion of the dendritic conductive fine particles (B) used in the conductive layer is preferably 50% to 90% by weight and more preferably 60% to 80% by weight in 100% by weight of the conductive layer. When the amount used is 50% by weight or more, desired conductivity tends to be easily obtained. On the other hand, when the amount is 90% by weight or less, the amount of resin for forming a sheet tends to be easily secured.
　デンドライト状導電性微粒子（Ｂ）は、球状導電性微粒子やフレーク状導電性微粒子（図１Ｂ参照）と比較すると、樹の枝のような形状をしているため、１つ１つの粒子間に隙間を形成しやすい。そのため、デンドライト状導電性微粒子（Ｂ）を使用して導電層を形成すると、空隙が生じやすい。デンドライト状導電性微粒子（Ｂ）を用いることにより、球状導電性粒子やフレーク状導電性微粒子を主成分として使用した導電性シートを同一条件で加熱プレスする場合と比較して、横方向への染み出しをより低減できる。 The dendrite-like conductive fine particles (B) are shaped like tree branches as compared with spherical conductive fine particles or flaky conductive fine particles (see FIG. 1B). Easy to form. Therefore, when a conductive layer is formed using dendritic conductive fine particles (B), voids are likely to occur. By using the dendritic conductive fine particles (B), it is possible to stain in the horizontal direction compared to the case where conductive sheets using spherical conductive particles or flaky conductive fine particles as the main component are heated and pressed under the same conditions. It is possible to reduce the ejection more.
　導電層には、熱硬化性樹脂（Ａ）とデンドライト状導電性微粒子（Ｂ）の他、本発明の趣旨を逸脱しない範囲で他の添加剤を加えることができる。例えば、シランカップリング剤、酸化防止剤、顔料、染料、粘着付与樹脂、可塑剤、紫外線吸収剤、消泡剤、レベリング調整剤、充填剤、難燃剤等を含むことができる。 In addition to the thermosetting resin (A) and the dendritic conductive fine particles (B), other additives can be added to the conductive layer without departing from the spirit of the present invention. For example, silane coupling agents, antioxidants, pigments, dyes, tackifying resins, plasticizers, ultraviolet absorbers, antifoaming agents, leveling regulators, fillers, flame retardants and the like can be included.
　続いて、第１実施形態の導電性シートの製造方法について説明する。まず、少なくとも熱硬化性樹脂（Ａ）と、デンドライト状導電性微粒子（Ｂ）を混合することで導電性樹脂組成物（Ｃ）を調合する。混合方法は、特に限定されないが、好ましい例としてミキサー、ディソルバー、フーバーマーラー、３本ロールミル、サンドミル等を使用する方法が挙げられる。 Then, the manufacturing method of the electroconductive sheet of 1st Embodiment is demonstrated. First, a conductive resin composition (C) is prepared by mixing at least a thermosetting resin (A) and dendritic conductive fine particles (B). The mixing method is not particularly limited, but preferred examples include a method using a mixer, a dissolver, a Hoover Mahler, a three-roll mill, a sand mill, and the like.
　導電性樹脂組成物（Ｃ）を用いて、例えば、剥離シート上に塗工して導電層の塗膜を形成する。塗工方法は特に限定されず、従来公知の方法を制限なく利用できる。例えば、グラビアコート方式、キスコート方式、ダイコート方式、リップコート方式、コンマコート方式、ブレードコート方式、ロールコート方式、ナイフコート方式、スプレーコート方式、バーコート方式、スピンコート方式、ディップコート方式等により塗膜を形成する。 Using the conductive resin composition (C), for example, it is coated on a release sheet to form a conductive layer coating. The coating method is not particularly limited, and a conventionally known method can be used without limitation. For example, gravure coating, kiss coating, die coating, lip coating, comma coating, blade coating, roll coating, knife coating, spray coating, bar coating, spin coating, dip coating, etc. A film is formed.
　導電層の加熱プレスを行う前の厚みは、用途に応じて適宜設定できるが、５μｍ～１００μｍが好ましい。なお、厚みは、ＪＩＳＢ７５０３（ダイヤルゲージ）に則って測定した値である。 The thickness of the conductive layer before being hot-pressed can be appropriately set according to the use, but is preferably 5 μm to 100 μm. The thickness is a value measured according to JISB7503 (dial gauge).
　第１実施形態の導電性シートの加熱プレス後の膜厚は、デンドライト状導電性微粒子（Ｂ）の平均粒子径Ｄ５０の０．２５倍～１０倍であることが好ましく、０．５倍～５倍がより好ましい。 The film thickness of the conductive sheet of the first embodiment after hot pressing is preferably 0.25 to 10 times the average particle diameter D 50 of the dendritic conductive fine particles (B), preferably 0.5 to 5 times is more preferable.
　第１実施形態の導電性シートの用途は特に限定されず、導電性シートを貼り付けて使用したい用途全般に対して利用できる。例えば、プリント配線板に貼り付けて電磁波シールドをする目的で用いたり、プリント配線板に形成した回路のアースを取る為に使用することができる。また、電子レンジ等の家電をはじめとする各種電子機器等に貼り付けて使用できる。 The application of the conductive sheet of the first embodiment is not particularly limited, and can be used for all applications in which a conductive sheet is desired to be used. For example, it can be used for the purpose of attaching an electromagnetic wave shield to a printed wiring board, or for grounding a circuit formed on the printed wiring board. Further, it can be used by being attached to various electronic devices such as home appliances such as a microwave oven.
　第１実施形態の導電性シートによれば、特許文献１のように、３層構造とせずに１層のみだけでも、熱可塑性樹脂を用いることにより被着体への接着力を発現させることができる。その結果、薄膜用途にも利用できるという優れたメリットがある。また、特許文献１のように金属箔を用いずに、熱可塑性樹脂とデンドライト状導電性微粒子を必須構成成分とする導電層を用いているので、フレキシブル性に優れている。従って、フレキシブルプリント配線板等に好適に適用できる。また、導電性微粒子として、デンドライト状の導電性微粒子を用いることにより、導電層内に空隙等を形成して加熱プレス時の染み出しを空隙により吸収することができる。その結果、導電層の染み出しを最小限の抑制することができる。また、高温環境下において使用が難しい耐熱性の低い樹脂等においてもデンドライト状導電性微粒子を用いることにより、導電層の染み出しを効果的に抑制できる。本発明の導電性シートによれば、高温・高湿等の過酷な条件下で使用される用途としても好適に利用できる。 According to the conductive sheet of the first embodiment, as in Patent Document 1, even if only one layer is used instead of a three-layer structure, an adhesive force to an adherend can be expressed by using a thermoplastic resin. it can. As a result, there is an excellent merit that it can be used for thin film applications. Moreover, since the electroconductive layer which uses a thermoplastic resin and dendritic electroconductive fine particles as an essential component is used without using metal foil like patent document 1, it is excellent in flexibility. Therefore, it can be suitably applied to flexible printed wiring boards and the like. Further, by using dendritic conductive fine particles as the conductive fine particles, voids or the like can be formed in the conductive layer, and the seepage during heat pressing can be absorbed by the voids. As a result, the seepage of the conductive layer can be minimized. In addition, even in a resin having low heat resistance that is difficult to use in a high temperature environment, the use of dendritic conductive fine particles can effectively suppress the seepage of the conductive layer. According to the conductive sheet of the present invention, it can be suitably used as an application used under severe conditions such as high temperature and high humidity.
［第２実施形態］
　次に、上記第１実施形態とは異なる導電性シートの一例について説明する。第２実施形態に係る導電性シートは、絶縁層と、上記第１実施形態の導電層とが積層された絶縁層付きの導電性シートである。 [Second Embodiment]
Next, an example of a conductive sheet different from the first embodiment will be described. The conductive sheet according to the second embodiment is a conductive sheet with an insulating layer in which an insulating layer and the conductive layer of the first embodiment are stacked.
　第２実施形態の導電性シートに用いられる絶縁層は、本発明の趣旨を逸脱しない範囲で特に限定されない。絶縁層の素材は、特に限定されないが、例えば、導電層で使用できる熱硬化性樹脂（Ａ）など絶縁性を有する樹脂を使用することが好ましい。また、ポリエステル、ポリカーボネート、ポリイミド、ポリフェニレンサルファイドなどのプラスチックフィルムを使用することもできる。 The insulating layer used in the conductive sheet of the second embodiment is not particularly limited as long as it does not depart from the spirit of the present invention. Although the raw material of an insulating layer is not specifically limited, For example, it is preferable to use resin which has insulation, such as the thermosetting resin (A) which can be used with a conductive layer. Moreover, plastic films, such as polyester, a polycarbonate, a polyimide, polyphenylene sulfide, can also be used.
　また絶縁層には、必要に応じてシランカップリング剤、酸化防止剤、顔料、染料、粘着付与樹脂、可塑剤、紫外線吸収剤、消泡剤、レベリング調整剤、充填剤、難燃剤等を含むこともできる。 Further, the insulating layer contains a silane coupling agent, an antioxidant, a pigment, a dye, a tackifier resin, a plasticizer, an ultraviolet absorber, an antifoaming agent, a leveling adjusting agent, a filler, a flame retardant and the like as necessary. You can also.
　第２実施形態の導電性シートの用途は、特に限定されないが、例えば、導電層側をプリント配線板の外側主面に貼着せしめて電磁波シールドフィルムとして利用することができる。 Although the use of the conductive sheet of the second embodiment is not particularly limited, for example, the conductive layer side can be attached to the outer main surface of the printed wiring board and used as an electromagnetic wave shielding film.
　第２実施形態の導電性シートの絶縁層の形成方法、及び導電層と絶縁層との積層方法は、公知の方法を制限なく使用できる。例えば、予め形成してある絶縁層上に導電層を形成したり、第１実施形態で説明した導電層と同様の製造方法により絶縁層に形成したりすることができる。絶縁層の厚さは、用途によっても異なるが、例えば、５μｍ～５０μｍが好ましい。 A well-known method can be used for the formation method of the insulating layer of the electroconductive sheet of 2nd Embodiment, and the lamination | stacking method of an electroconductive layer and an insulating layer without a restriction | limiting. For example, a conductive layer can be formed on a previously formed insulating layer, or can be formed on the insulating layer by the same manufacturing method as the conductive layer described in the first embodiment. The thickness of the insulating layer varies depending on the application, but is preferably 5 μm to 50 μm, for example.
　第２実施形態によれば、第１実施形態と同様の導電層を有するので、第１実施形態と同様の効果を得ることができる。また、絶縁層との積層体とすることにより、導電性シートの機械的強度を高めたり、表面に絶縁特性を付与したりすることができる。 According to the second embodiment, since the conductive layer is the same as that of the first embodiment, the same effect as that of the first embodiment can be obtained. Moreover, by using a laminated body with an insulating layer, it is possible to increase the mechanical strength of the conductive sheet or to impart insulating characteristics to the surface.
　なお、第２実施形態においては、絶縁層と導電層を積層する導電性シートの例を説明したが、導電層と積層する層は、特に限定されず目的に応じて種々の機能を有する層を積層することができる。例えば、支持層や半導体層、保護膜、反射防止フィルム等の光学フィルム等を積層した導電性シートであってもよい。 In the second embodiment, the example of the conductive sheet for laminating the insulating layer and the conductive layer has been described. However, the layer for laminating the conductive layer is not particularly limited, and layers having various functions are used depending on the purpose. Can be stacked. For example, the electroconductive sheet which laminated | stacked optical films, such as a support layer, a semiconductor layer, a protective film, and an antireflection film, may be sufficient.
［第３実施形態］
　次に、上記第１実施形態とは異なる製造方法により製造した導電性シートの例について説明する。第３実施形態の導電性シートの製造方法は、第１実施形態で説明した加熱プレス前に、プレス工程を含む点において第１実施形態の導電性シートの製造方法と相違する。それ以外の点については、第１実施形態で説明した工程と同様であり、用いる導電層の構成も同様である。 [Third Embodiment]
Next, an example of a conductive sheet manufactured by a manufacturing method different from that of the first embodiment will be described. The method for manufacturing a conductive sheet according to the third embodiment is different from the method for manufacturing a conductive sheet according to the first embodiment in that a press process is included before the hot pressing described in the first embodiment. About other points, it is the same as that of the process demonstrated in 1st Embodiment, and the structure of the conductive layer to be used is also the same.
　第３実施形態の導電性シートは、塗工して導電層を形成した後であって、被着体と接着する際に加熱プレスを行う前に、加圧工程（以下、被着体と導電性シートを加熱プレスする工程と区別するために「プレ加圧工程」という）を行うことにより製造したものである。プレ加圧工程は、用途により適宜変更し得るが、２．５ＭＰa～５０ＭＰa（２５ｋｇ／ｃｍ２～５１０ｋｇ／ｃｍ２の圧力を加えることが好ましい。温度は、加熱することを排除するものではないが、デンドライト状導電性微粒子（Ｂ）の変形や折れを誘起し、熱可塑性樹脂の流動を促す目的ではないので、加熱しない、若しくは、熱可塑性樹脂の流動を促す温度以下の加熱とすることが好ましい。 The conductive sheet of the third embodiment is formed after applying and forming a conductive layer, and before performing a heat press when adhering to the adherend, a pressurizing step (hereinafter referred to as adherend and conductive). In order to distinguish it from the step of heat-pressing the adhesive sheet, it is manufactured by performing a “pre-pressurization step”. Although the pre-pressurization step can be appropriately changed depending on the application, it is preferable to apply a pressure of 2.5 MPa to 50 MPa (25 kg / cm 2 to 510 kg / cm 2. Although the temperature does not exclude heating. It is not intended to induce deformation or breakage of the dendritic conductive fine particles (B) and to promote the flow of the thermoplastic resin. Therefore, it is preferable that the heating is not performed or the temperature is not higher than the temperature that promotes the flow of the thermoplastic resin. .
　被着体と導電性シートを接合する前に予め導電性シートに圧力を加えてデンドライト状導電性微粒子（Ｂ）を変形させたり、樹枝状の粒子を折ったりすることで、デンドライト状導電性微粒子（Ｂ）同士の接触が密になり導電層の導電特性をより向上させることができる。
　導電性シートに圧力を加える方法としては、平板プレス機、ロールプレス機等を用いる方法がある。これらの中でも圧力を高めやすい（線圧を高められる）ロールプレス機が好ましい。使用するロールは、金属ロール及び樹脂ロール等の表面硬度が異なるロールを使用できる。この加圧後の導電性シートを使用して、プリント配線板等の被着体と接合して加熱プレスをすることで導電層の染み出しをより効果的に抑制できる。 Before joining the adherend and the conductive sheet, pressure is applied to the conductive sheet in advance to deform the dendritic conductive fine particles (B) or fold the dendritic particles, thereby dendritic conductive fine particles (B) The contact between each other becomes dense, and the conductive properties of the conductive layer can be further improved.
As a method for applying pressure to the conductive sheet, there is a method using a flat plate press, a roll press or the like. Among these, a roll press machine that can easily increase the pressure (increase the linear pressure) is preferable. As the roll to be used, rolls having different surface hardnesses such as a metal roll and a resin roll can be used. By using the pressed conductive sheet and bonding to an adherend such as a printed wiring board and performing a heat press, the bleeding of the conductive layer can be more effectively suppressed.
　第３実施形態の導電層は、プレ加圧工程を行うものであるが、被着体と導電性シートを接合する際には第１実施形態で述べたように、１５０℃、２ＭＰａ、３０分間の条件で加熱プレスした後の厚みが、加熱プレス前の当該導電層の厚みを１００としたときに３０以上、９５以下の範囲になるものである必要がある。すなわち、プレ加圧工程を経た後の被着体との接合前の導電層の厚みに対して、上記条件で加熱プレス（１５０℃、２ＭＰａ、３０分間の条件で加熱プレス）をした場合の厚み変化が上記範囲（導電層の厚みを１００としたときに３０以上、９５以下の範囲）に含まれるものである必要がある。なお、上記条件を満たすものであればよく、プレ加圧工程において膜厚が変化するものであってもよい。プレ加圧工程において膜厚が変化するものであっても、熱可塑性樹脂組成物やブリードした低分子量成分の移動を吸収するための空隙が存在していれば、被着体と導電性シートを接合する際に加熱プレスしても、導電層の染み出しを効果的に抑制できるからである。 The conductive layer of the third embodiment performs a pre-pressurization step. When the adherend and the conductive sheet are joined, as described in the first embodiment, 150 ° C., 2 MPa, 30 minutes. The thickness after the heat pressing under the above conditions needs to be in the range of 30 or more and 95 or less when the thickness of the conductive layer before the heat pressing is 100. That is, the thickness of the conductive layer before joining to the adherend after the pre-pressurization step is heated under the above conditions (150 ° C., 2 MPa, heated for 30 minutes). The change needs to be included in the above range (a range of 30 or more and 95 or less when the thickness of the conductive layer is 100). In addition, what satisfy | fills the said conditions may be sufficient, and a film thickness may change in a pre-pressurization process. Even if the film thickness changes in the pre-pressurization step, the adherend and the conductive sheet can be removed if there is a gap for absorbing the movement of the thermoplastic resin composition or the bleed low molecular weight component. This is because even if heat-pressing at the time of joining, the seepage of the conductive layer can be effectively suppressed.
　第３実施形態によれば、第１実施形態と同様の導電層を有する導電性シートを用いているので第１実施形態と同様の効果が得られる。また、プリント配線板等と導電性シートを加熱プレスする前に予め導電層をプレスしてデンドライト状導電性微粒子（Ｂ）を潰しているので、導電特性を効果的に引き出すことができるというメリットがある。 According to the third embodiment, since the conductive sheet having the same conductive layer as in the first embodiment is used, the same effect as in the first embodiment can be obtained. In addition, since the conductive layer is pressed in advance and the dendritic conductive fine particles (B) are crushed before the printed wiring board and the conductive sheet are heated and pressed, there is a merit that the conductive characteristics can be effectively extracted. is there.
　なお、第３実施形態においては、導電層を１層有する導電性シートの例について説明したが、第２実施形態のように絶縁層付きの導電性シートや、他の層が積層された導電性シートにおいても第３実施形態のプレ加圧工程を好適に付加することができる。導電性シートを絶縁層付きの導電性シートとする場合、プレ加圧工程を行う時期は制限されないが、絶縁層を積層する前にプレ加圧工程を行うことがより好ましい。導電層にプレ加圧工程を行うと導電層の表面がより平滑になるため、さらに絶縁層を積層する場合は、絶縁層の厚み精度が向上するため、絶縁層の厚みが薄くとも所望の絶縁特性が得やすくなる。 In the third embodiment, an example of a conductive sheet having one conductive layer has been described. However, as in the second embodiment, a conductive sheet with an insulating layer or a conductive layer in which other layers are stacked. Also in the sheet, the pre-pressurization step of the third embodiment can be suitably added. When the conductive sheet is a conductive sheet with an insulating layer, the timing of performing the pre-pressurization step is not limited, but it is more preferable to perform the pre-pressurization step before laminating the insulating layer. When the pre-pressurization process is performed on the conductive layer, the surface of the conductive layer becomes smoother. When the insulating layer is further laminated, the thickness accuracy of the insulating layer is improved. It becomes easy to obtain characteristics.
　［第４実施形態］
　次に、上記第１実施形態とは異なる導電性シートの一例について説明する。第４実施形態に係る導電性シートは、１層の導電層からなる。第４実施形態の導電性シートの導電層は、熱硬化性樹脂（Ａ）と、デンドライト状導電性微粒子（Ｂ）を必須構成として含むものであり、導電層中のデンドライト状導電性微粒子（Ｂ）の平均粒子径Ｄ９０が、導電層の膜厚に対して０．５～３倍の範囲内にあるものである。 [Fourth Embodiment]
Next, an example of a conductive sheet different from the first embodiment will be described. The conductive sheet according to the fourth embodiment includes a single conductive layer. The conductive layer of the conductive sheet according to the fourth embodiment includes a thermosetting resin (A) and dendritic conductive fine particles (B) as essential components, and dendritic conductive fine particles (B the average particle diameter D 90 of) is intended for a film thickness of the conductive layer is in the range of 0.5 to 3 times.
　なお、第１実施形態において特定していた導電層の厚みが、１５０℃、２ＭＰａ、３０分間の条件で加熱プレスした後の厚みが、加熱プレス前の当該導電層の厚みを１００としたときに３０以上、９５以下の範囲になるものであることは必ずしも必要ではない。これは、導電層の膜厚に対して、デンドライト状導電微粒子（Ｂ）の平均粒子径Ｄ９０を３倍以下にすることで、微粒子の先端が、加熱プレスをかける際に導電層から突き出にくい傾向になるからである。また、平均粒子径Ｄ９０を０．５倍以上にすることで、導電層に空隙が過剰に生じにくくなるからである。但し、導電層の染み出しをより効果的に防止する観点からは、１５０℃、２ＭＰａ、３０分間の条件で加熱プレスした後の厚みが、加熱プレス前の当該導電層の厚みを１００としたときに３０以上、９５以下の範囲にあるという条件も満たすことがより好ましい。 In addition, when the thickness of the conductive layer specified in the first embodiment is 150 ° C., 2 MPa, and the thickness of the conductive layer after 30 minutes is 30 minutes, the thickness of the conductive layer before the hot press is 100. It is not always necessary to be in the range of 30 or more and 95 or less. This is for a film thickness of the conductive layer, by an average particle diameter D 90 of the dendrite conductive fine particles (B) to 3 times or less, the tip of the fine particles, not easily protrude from the conductive layer when applying the heat press Because it becomes a tendency. Further, the average particle diameter D 90 by more than 0.5 times, because the gap in the conductive layer is less likely excessively occur. However, from the viewpoint of more effectively preventing the conductive layer from exuding, when the thickness after hot pressing under conditions of 150 ° C., 2 MPa, 30 minutes is 100, the thickness of the conductive layer before hot pressing is 100 Further, it is more preferable to satisfy the condition of being in the range of 30 to 95.
　第４実施形態の導電性シートは、プリント配線板等の被着体に、第４実施形態の導電性シートの導電層側が接するように積層し、第１実施形態で説明した加熱プレス工程を経ることにより、被着体に導電性シートを貼着せしめることができる。第４実施形態の導電性シートによれば、導電層に熱可塑性樹脂を含有させているので、被着体との接着性を良好に保つことができる。なお、加熱プレスの条件は、導電層の用途やニーズに応じて（例えば、求められる導電特性や空隙の割合等に応じて）任意に設定できる。 The conductive sheet of the fourth embodiment is laminated so that the conductive layer side of the conductive sheet of the fourth embodiment is in contact with an adherend such as a printed wiring board, and is subjected to the heat press step described in the first embodiment. By this, a conductive sheet can be stuck on a to-be-adhered body. According to the electroconductive sheet of 4th Embodiment, since the thermoplastic resin is contained in the electroconductive layer, adhesiveness with a to-be-adhered body can be maintained favorable. In addition, the conditions of a heat press can be arbitrarily set according to the use and needs of a conductive layer (for example, according to the electroconductive characteristic calculated | required, the ratio of the space | gap, etc.).
　第４実施形態の導電性シートは、導電層においてデンドライト状導電性微粒子（Ｂ）の空隙を加熱プレスにより埋めることが好ましいが、埋めないで空隙として利用することも可能である。例えば、加熱プレス工程を行わずに、例えば、接着剤層を介して被着体と導電性シートを接合してもよい。接着剤層を介する方法は、特に限定されないが、例えば、導電層とは別の接着剤層を導電性シートに設け、若しくは被着体側に接着剤層を設けて接着剤層を介して被着体を接合する方法が挙げられる。 In the conductive sheet of the fourth embodiment, it is preferable to fill the voids of the dendritic conductive fine particles (B) in the conductive layer with a hot press, but it is also possible to use them as voids without filling them. For example, the adherend and the conductive sheet may be joined via an adhesive layer, for example, without performing the heat press step. The method through the adhesive layer is not particularly limited. For example, an adhesive layer different from the conductive layer is provided on the conductive sheet, or an adhesive layer is provided on the adherend side and the adhesive layer is attached via the adhesive layer. The method of joining the body is mentioned.
　導電層を構成する熱可塑性樹脂（Ａ）の好ましい例は、第１実施形態で述べたとおりである。また、導電層には、熱可塑性樹脂（Ａ）と併用して硬化剤を用いることが好ましい。硬化剤の例についても第１実施形態で述べたとおりである。 Preferred examples of the thermoplastic resin (A) constituting the conductive layer are as described in the first embodiment. In addition, it is preferable to use a curing agent in combination with the thermoplastic resin (A) for the conductive layer. Examples of the curing agent are also as described in the first embodiment.
　デンドライト状導電性微粒子（Ｂ）の好ましい態様、素材は、第１実施形態において述べたものを好適に適用できる。 As preferred embodiments and materials of the dendritic conductive fine particles (B), those described in the first embodiment can be suitably applied.
　デンドライト状導電性微粒子（Ｂ）は、平均粒子径Ｄ５０が３μｍ～５０μｍであり、かつ平均粒子径Ｄ９０が平均粒子径Ｄ５０の１．５～５倍であることが好ましい。また、平均粒子径Ｄ５０は３μｍ～４０μｍがより好ましく、５μｍ～２５μｍがさらに好ましい。平均粒子径Ｄ５０が３μｍ以上になることで、導電層に空隙が出来やすくなり、染み出しを低減できる。一方、平均粒子径Ｄ５０が５０μｍ以下になることで、適切な厚さの導電層を形成しやすくなる。 The dendritic conductive fine particles (B) preferably have an average particle diameter D 50 of 3 μm to 50 μm and an average particle diameter D 90 of 1.5 to 5 times the average particle diameter D 50 . Further, the average particle size D 50 is more preferably 3 μm to 40 μm, and further preferably 5 μm to 25 μm. Mean By particle diameter D 50 is equal to or greater than 3 [mu] m, easily can voids in the conductive layer, it can be reduced exudation. On the other hand, the average particle diameter D 50 is 50μm or less, it becomes easy to form the conductive layer of the appropriate thickness.
　デンドライト状導電性微粒子（Ｂ）の平均粒子径Ｄ９０は、平均粒子径Ｄ５０の１．５倍～５倍が好ましく、２倍～３．５倍がより好ましい。平均粒子径Ｄ９０の値は、平均粒子径Ｄ５０の平均粒子径に依存する傾向にあるが、４．５μｍ～２５０μｍが好ましい。その理由は、第１実施形態で述べたとおりである。 The average particle diameter D 90 of the dendrite conductive fine particles (B) is preferably from 1.5 to 5 times the average particle diameter D 50, 2-fold to 3.5-fold and more preferably. The value of the average particle diameter D 90 tends to depend on the average particle diameter of the average particle diameter D 50 , but is preferably 4.5 μm to 250 μm. The reason is as described in the first embodiment.
　デンドライト状導電性微粒子（Ｂ）は、タップ密度（以下、「ＴＤ」ともいう）が、０．８ｇ／ｃｍ３～２．５ｇ／ｃｍ３であることが好ましい。また、デンドライト状導電性微粒子（Ｂ）は、見掛密度（以下、「ＡＤ」ともいう）が０．４ｇ／ｃｍ３～１．５ｇ／ｃｍ３あることが好ましい。さらに、デンドライト状導電性微粒子（Ｂ）は、ＡＤとＴＤの比率（ＡＤ／ＴＤ）が０．３～０．９であることがより好ましい。これらの理由は、第１実施形態で述べたとおりである。 The dendrite-like conductive fine particles (B) preferably have a tap density (hereinafter also referred to as “TD”) of 0.8 g / cm 3 to 2.5 g / cm 3 . The dendritic conductive fine particles (B) preferably have an apparent density (hereinafter also referred to as “AD”) of 0.4 g / cm 3 to 1.5 g / cm 3 . Furthermore, it is more preferable that the dendritic conductive fine particles (B) have an AD / TD ratio (AD / TD) of 0.3 to 0.9. These reasons are as described in the first embodiment.
　第４実施形態の導電性シートの厚みは、特に限定されないが、５μｍ～１００μｍが好ましく、１０μｍ～５０μｍがより好ましい。なお、厚みは、ＪＩＳＢ７５０３（ダイヤルゲージ）に則って測定した値である。導電層の厚みが５μｍ以上になると導電性が得やすくなる。また、１００μｍ以下になることで屈曲性のバランスがとりやすくなる。 The thickness of the conductive sheet of the fourth embodiment is not particularly limited, but is preferably 5 μm to 100 μm, and more preferably 10 μm to 50 μm. The thickness is a value measured according to JISB7503 (dial gauge). When the thickness of the conductive layer is 5 μm or more, conductivity is easily obtained. Further, when the thickness is 100 μm or less, it becomes easy to balance the flexibility.
　導電層中にデンドライト状導電性微粒子（Ｂ）を使用する割合は、導電層１００重量％中、５０重量％～９０重量％が好ましく、６０重量％～８０重量％がより好ましい。その理由は、第１実施形態で述べたとおりである。また、第４実施形態の導電層においても、必要に応じて添加剤を加えることができ、その一例として、第１実施形態で述べた添加剤を挙げることができる。また、導電性シートの製造方法は、第１実施形態で述べたとおりである。 The proportion of the dendritic conductive fine particles (B) used in the conductive layer is preferably 50% to 90% by weight and more preferably 60% to 80% by weight in 100% by weight of the conductive layer. The reason is as described in the first embodiment. Also, in the conductive layer of the fourth embodiment, an additive can be added as necessary, and examples thereof include the additives described in the first embodiment. Moreover, the manufacturing method of an electroconductive sheet is as having described in 1st Embodiment.
　第４実施形態によれば、上記第１実施形態と同様の効果が得られる。また、導電層の厚みとして、導電層中のデンドライト状導電性微粒子（Ｂ）の平均粒子径Ｄ９０が、導電層の膜厚に対して０．５～３倍の範囲内にあるものを用いることにより、導電層の膜厚と平均粒子径Ｄ９０を設計することによって、導電層の染み出しを最小限にすることができる信頼性の高い導電性シートを提供することができるというメリットがある。 According to the fourth embodiment, the same effect as in the first embodiment can be obtained. In addition, as the thickness of the conductive layer, a dendrite-like conductive fine particle (B) in the conductive layer having an average particle diameter D 90 in the range of 0.5 to 3 times the thickness of the conductive layer is used. Thus, by designing the film thickness and average particle diameter D 90 of the conductive layer, there is a merit that it is possible to provide a highly reliable conductive sheet that can minimize the seepage of the conductive layer. .
［第５実施形態］
　次に、第５実施形態の導電性シートとして電磁波シールドフィルムに適用した例について説明する。第５実施形態の導電性シートは、絶縁層と第４実施形態の導電層が積層されたものである。用途として、例えば、プリント配線板等の電子部品に貼着せしめる電磁波シールドフィルムとして利用できる。なお、電磁波シールドフィルムは、絶縁層と導電層以外の他の層（例えば、保護層、接着層）が積層されていてもよい。 [Fifth Embodiment]
Next, an example in which the conductive sheet of the fifth embodiment is applied to an electromagnetic wave shielding film will be described. The conductive sheet of the fifth embodiment is a laminate of the insulating layer and the conductive layer of the fourth embodiment. As an application, for example, it can be used as an electromagnetic wave shielding film to be attached to an electronic component such as a printed wiring board. The electromagnetic wave shielding film may be laminated with other layers (for example, a protective layer and an adhesive layer) other than the insulating layer and the conductive layer.
　絶縁層に用いる材料は、特に限定されないが、好ましい例としては、第２実施形態で述べたものを挙げることができる。また、絶縁層には、必要に応じて、シランカップリング剤、酸化防止剤、顔料、染料、粘着付与樹脂、可塑剤、紫外線吸収剤、消泡剤、レベリング調整剤、充填剤、難燃剤などを含むこともできる。絶縁層の形成方法については、第２実施形態で述べたとおりである。 The material used for the insulating layer is not particularly limited, but preferred examples include those described in the second embodiment. In addition, for the insulating layer, silane coupling agents, antioxidants, pigments, dyes, tackifier resins, plasticizers, ultraviolet absorbers, antifoaming agents, leveling regulators, fillers, flame retardants, etc., as necessary Can also be included. The method for forming the insulating layer is as described in the second embodiment.
　また、絶縁層の厚みは、導電層の厚みを１００とするときに、５０～２００の割合が好ましい。前記範囲内の厚みにすることで電磁波シールドフィルムの物性バランスを取りやすくなる。なお、第５実施形態の導電性シートの導電層は、必ずしも加熱プロセスを経る必要はなく、上記導電層の膜厚は、実際に利用する際の膜厚を示すものであり、加熱プロセス前のものであっても、加熱プロセス後であってもよい。 In addition, the thickness of the insulating layer is preferably 50 to 200 when the thickness of the conductive layer is 100. By making the thickness within the above range, it becomes easy to balance the physical properties of the electromagnetic wave shielding film. In addition, the conductive layer of the conductive sheet of the fifth embodiment does not necessarily need to undergo a heating process, and the film thickness of the conductive layer indicates a film thickness when actually used, and before the heating process. Even after the heating process.
　電磁波シールドフィルムを貼着することができる被着体としては、特に限定されないが、例えば、繰り返し屈曲を受けるフレキシブルプリント配線板を代表例として挙げることができる。もちろん、リジッドプリント配線板をはじめとする各種基板、電磁波シールドが要求される電子レンジ等の家電や、電子機器全般、電磁波をシールドしたい部材全般に適用できる。 The adherend to which the electromagnetic wave shielding film can be attached is not particularly limited, and for example, a flexible printed wiring board that is repeatedly bent can be given as a representative example. Of course, the present invention can be applied to various substrates such as rigid printed wiring boards, home appliances such as microwave ovens that require electromagnetic shielding, general electronic devices, and general members that want to shield electromagnetic waves.
　第５実施形態に係る電磁波シールドフィルムによれば、上記実施形態と同様の効果が得られる。 According to the electromagnetic wave shielding film according to the fifth embodiment, the same effect as in the above embodiment can be obtained.
　以下、実施例、比較例を挙げて本発明を詳細に説明するが、本発明は以下の実施例のみに限定されるものではない。なお、以下の「部」及び「％」は、それぞれ「重量部」及び「重量％」に基づく値である。 Hereinafter, the present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples. The following “parts” and “%” are values based on “parts by weight” and “% by weight”, respectively.
　平均粒子径Ｄ５０及び平均粒子径Ｄ９０は、日機装社製のマイクロトラックＭＴ３３００を使用して測定した。見掛密度は、ＪＩＳ　Ｚ　２５０４：２０００に定められた金属粉の見掛密度試験方法により求めた。タップ密度は、ＪＩＳ　Ｚ　２５１２：金属粉―タップ密度測定方法により求めた。 The average particle diameter D 50 and the average particle diameter D 90 were measured using a Microtrac MT3300 manufactured by Nikkiso Co., Ltd. The apparent density was determined by an apparent density test method for metal powder defined in JIS Z 2504: 2000. The tap density was determined by JIS Z 2512: Metal powder-tap density measurement method.
　＜実施例１～５＞
　デンドライト状導電性微粒子として、表１Ａの材料を用い、熱硬化性樹脂としては、ウレタン樹脂（トーヨーケム社製）を用いて導電性シートを作製した。デンドライト状導電性微粒子（Ｂ）と熱硬化性樹脂（Ａ）の比率は、樹脂固形分１００重量部に対してデンドライト状導電性微粒子（Ｂ）を２５０重量部とした。そして、乾燥膜厚が１０μｍになるように、表面を剥離処理した厚み１００μｍのポリエチレンテレフタレートフィルム上に、バーコーターを用いて塗工し、１００℃で３分乾燥させて導電性シートを得た。 <Examples 1 to 5>
A conductive sheet was prepared using the materials shown in Table 1A as the dendritic conductive fine particles, and using a urethane resin (manufactured by Toyochem) as the thermosetting resin. The ratio of dendritic conductive fine particles (B) to thermosetting resin (A) was 250 parts by weight of dendritic conductive fine particles (B) with respect to 100 parts by weight of resin solids. And it coated using the bar-coater on the 100-micrometer-thick polyethylene terephthalate film which peel-processed the surface so that a dry film thickness might be 10 micrometers, and it was made to dry at 100 degreeC for 3 minutes, and obtained the electroconductive sheet.
　＜実施例６～１０＞
　実施例１～５で得られた導電性シートの片面上に絶縁層としてウレタン樹脂（トーヨーケム社製）を用い、乾燥膜厚が１０μｍになるように塗工・乾燥し、総厚２０μｍの絶縁層付き導電性シートを得た。 <Examples 6 to 10>
Using a urethane resin (manufactured by Toyochem Co., Ltd.) as an insulating layer on one side of the conductive sheets obtained in Examples 1 to 5, coating and drying to a dry film thickness of 10 μm, an insulating layer having a total thickness of 20 μm An attached conductive sheet was obtained.
　＜実施例１１＞
　実施例２で得られた導電性シート表面を、ロールプレス機を使用して３ＭＰaの圧力がかかるようにプレ加圧した。その後プレ加圧した導電性シート面に、絶縁層としてウレタン樹脂（トーヨーケム社製）を乾燥膜厚が１０μｍになるように塗工・乾燥することで総厚２０μｍの絶縁層付き導電性シートを得た。 <Example 11>
The surface of the conductive sheet obtained in Example 2 was pre-pressurized using a roll press so that a pressure of 3 MPa was applied. Then, a conductive sheet with an insulating layer having a total thickness of 20 μm is obtained by applying and drying urethane resin (manufactured by Toyochem) as an insulating layer on the pre-pressurized conductive sheet surface so that the dry film thickness becomes 10 μm. It was.
　＜実施例１２、１３＞
　プレ加圧する圧力を、それぞれ１０ＭＰa、４０ＭＰaに変更した以外は、実施例１１と同様にして絶縁層付き導電性シートを得た。 <Examples 12 and 13>
A conductive sheet with an insulating layer was obtained in the same manner as in Example 11 except that the prepressurizing pressure was changed to 10 MPa and 40 MPa, respectively.
　＜比較例１～２＞
　表１Ｂに示す導電性微粒子を用いて、実施例１～５と同様の方法で、導電性シートを得た。 <Comparative Examples 1 and 2>
Using conductive fine particles shown in Table 1B, conductive sheets were obtained in the same manner as in Examples 1 to 5.
　＜比較例３～４＞
　表１Ｂに示す導電性微粒子を用いて、実施例６～１０と同様の方法で、絶縁層付き導電性シートを得た。 <Comparative Examples 3 to 4>
Using the conductive fine particles shown in Table 1B, conductive sheets with insulating layers were obtained in the same manner as in Examples 6 to 10.
＜染み出し性評価＞
　厚さが５０μｍのポリイミドフィルム（東レ・デュポン社製「カプトン２００ＥＮ」）の一方の面に、各実施例、及び各比較例の導電性シートをラミネートにより貼付し、穴あけ機で直径５ｍｍの穴を貫通させた。
　別途、厚さが５０μｍのポリイミドフィルム（東レ・デュポン社製「カプトン２００ＥＮ」）を用意し、前述の導電性シートと１５０℃、３０分間、２．０ＭＰａの条件で加熱プレス処理することにより、ポリイミドフィルムによって挟持された導電性シートのサンプルを得た。加熱プレス処理後、導電性シートの穴部分を、拡大鏡を用いて観察し、染み出し量を測定した。評価基準は以下の通りである。
○：導電性シートの染み出し量が０．０１ｍｍ未満
△：導電性シートの染み出し量が０．０１ｍｍ以上０．０５ｍｍ未満
×：導電性シートの染み出し量が０．０５ｍｍ以上 <Exudation evaluation>
The conductive sheet of each example and each comparative example was pasted on one side of a polyimide film (“Kapton 200EN” manufactured by Toray DuPont) with a thickness of 50 μm, and a hole with a diameter of 5 mm was formed with a punching machine. Penetrated.
Separately, a polyimide film having a thickness of 50 μm (“Kapton 200EN” manufactured by Toray DuPont Co., Ltd.) was prepared, and the polyimide film was subjected to heat press treatment with the above-described conductive sheet at 150 ° C. for 30 minutes at 2.0 MPa. A sample of a conductive sheet sandwiched between films was obtained. After the heat press treatment, the hole portion of the conductive sheet was observed using a magnifying glass, and the amount of seepage was measured. The evaluation criteria are as follows.
○: The amount of exudation of the conductive sheet is less than 0.01 mm. Δ: The amount of exudation of the conductive sheet is 0.01 mm or more and less than 0.05 mm. ×: The amount of exudation of the conductive sheet is 0.05 mm or more.
＜接続抵抗値Ａの測定＞
　実施例１～５、及び比較例１、２の導電性シートについて、幅２０ｍｍ、長さ５０ｍｍのサンプルを用意し、別に作製したフレキシブルプリント配線板を用いて接続抵抗値Ａを測定した。具体的には、図２Ａ～図２Ｆに示すように、厚み１２．５μｍのポリイミドフィルム１上に、厚み１８μｍの銅箔からなり、電気的に接続されていない回路２が形成され、回路２上に、接着剤付きの、厚み３７．５μｍ、直径０．８ｍｍのスルーホール４を有するカバーフィルム３が積層されてなるフレキシブルプリント配線板を用意した。そして、カバーフィルム３上に導電性シート５を載置し、この導電性シート５上に表面が厚さ０．１μｍのニッケルで処理された厚さ２００μｍのステンレス板６を載せて、１５０℃、３０分間、２．０ＭＰａの条件で加熱プレスした。その後、回路２とステンレス板６間の縦方向の抵抗値を三菱化学社製「ロレスターＧＰ」の四探針プローブを用いて測定した。評価基準は以下の通りである。
○：２００ｍΩ未満
△：２００ｍΩ以上、５００ｍΩ未満
×：５００ｍΩ以上 <Measurement of connection resistance value A>
Samples having a width of 20 mm and a length of 50 mm were prepared for the conductive sheets of Examples 1 to 5 and Comparative Examples 1 and 2, and the connection resistance value A was measured using a separately prepared flexible printed wiring board. Specifically, as shown in FIGS. 2A to 2F, a circuit 2 made of copper foil having a thickness of 18 μm and not electrically connected is formed on a polyimide film 1 having a thickness of 12.5 μm. A flexible printed wiring board was prepared by laminating a cover film 3 having a through hole 4 having a thickness of 37.5 μm and a diameter of 0.8 mm, with an adhesive. Then, a conductive sheet 5 is placed on the cover film 3, and a 200 μm thick stainless steel plate 6 whose surface is treated with 0.1 μm thick nickel is placed on the conductive sheet 5 at 150 ° C., Heat pressing was performed for 30 minutes under the condition of 2.0 MPa. Thereafter, the resistance value in the vertical direction between the circuit 2 and the stainless steel plate 6 was measured using a four-point probe of “Lorester GP” manufactured by Mitsubishi Chemical Corporation. The evaluation criteria are as follows.
○: Less than 200 mΩ Δ: 200 mΩ or more, less than 500 mΩ x: 500 mΩ or more
＜接続抵抗値Ｂの測定＞
　実施例６～１３及び比較例３、４の絶縁層付き導電性シートについて、幅２０ｍｍ、長さ５０ｍｍのサンプルを用意し、別に作製したフレキシブルプリント配線板を用いて接続抵抗値Ｂを測定した。具体的には、図３Ａ～図３Ｆに示すように、厚み１２．５μｍのポリイミドフィルム１上に、厚み１８μｍの銅箔からなり、電気的に接続されてはいない回路２Ａ、回路２Ｂが形成されており、回路２Ａ上に、接着剤付きの、厚み３７．５μｍ、直径０．８ｍｍのスルーホール４を有するカバーフィルム３が積層されてなるフレキシブルプリント配線板を用意した。そして、カバーフィルム３上に導電性シート５を載置し、この導電性シート５上に表面が厚さ０．１μｍのニッケルで処理された厚さ２００μｍの絶縁層７を載せて、１５０℃、３０分間、２．０ＭＰａの条件で加熱プレスし、回路２Ａと回路２Ｂ間の抵抗値を三菱化学社製「ロレスターＧＰ」の四探針プローブを用いて測定した。評価基準は以下の通りである。
○：３００ｍΩ未満
△：３００ｍΩ以上、５００ｍΩ未満
×：５００ｍΩ以上 <Measurement of connection resistance value B>
For the conductive sheets with insulating layers of Examples 6 to 13 and Comparative Examples 3 and 4, samples having a width of 20 mm and a length of 50 mm were prepared, and the connection resistance value B was measured using a separately prepared flexible printed wiring board. Specifically, as shown in FIGS. 3A to 3F, circuits 2A and 2B made of copper foil having a thickness of 18 μm and not electrically connected are formed on a polyimide film 1 having a thickness of 12.5 μm. A flexible printed wiring board was prepared in which a cover film 3 having a through hole 4 having a thickness of 37.5 μm and a diameter of 0.8 mm was laminated on the circuit 2A. Then, a conductive sheet 5 is placed on the cover film 3, and a 200 μm thick insulating layer 7 whose surface is treated with 0.1 μm thick nickel is placed on the conductive sheet 5 at 150 ° C. Heating and pressing was performed for 30 minutes under the condition of 2.0 MPa, and the resistance value between the circuit 2A and the circuit 2B was measured using a four-point probe of “Lorestar GP” manufactured by Mitsubishi Chemical Corporation. The evaluation criteria are as follows.
○: Less than 300 mΩ Δ: 300 mΩ or more, less than 500 mΩ x: 500 mΩ or more
＜屈曲性＞
　幅６ｍｍ、長さ１２０ｍｍの実施例、及び比較例の導電性シートを、別に作製したフレキシブルプリント配線板（厚み２５μｍのポリイミドフィルム上に、厚み１２μｍの銅箔からなる回路パターンが形成されており、さらに回路パターン上に、接着剤付きの、厚み４０μｍのカバーフィルムが積層されてなる配線板）のカバーフィルム面に、１５０℃、３０分間、２．０ＭＰａ、の条件で圧着した。そして、曲率半径０．３８ｍｍ、荷重５００ｇ、速度１８０回／ｍｉｎの条件でＭＩＴ屈曲試験機にかけ、回路パターンが断線するまでの回数により耐屈曲性を評価した。評価基準は以下の通りである。
○：３０００回以上
△：２５００回以上、３０００回未満
×：２５００回未満 <Flexibility>
A flexible printed wiring board prepared separately from the conductive sheet of the example of width 6 mm and length 120 mm and the comparative example (a circuit pattern made of a 12 μm thick copper foil is formed on a 25 μm thick polyimide film, Furthermore, it was crimped | bonded on the conditions of 150 degreeC, 30 minutes, and 2.0 MPa conditions on the cover film surface of the wiring board by which a 40-micrometer-thick cover film with an adhesive was laminated | stacked on the circuit pattern. And it applied to the MIT bending test machine on conditions with a curvature radius of 0.38 mm, a load of 500 g, and a speed of 180 times / min, and the bending resistance was evaluated by the number of times until the circuit pattern was disconnected. The evaluation criteria are as follows.
○: 3000 times or more Δ: 2500 times or more and less than 3000 times ×: less than 2500 times
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表１Ａ、表１Ｂの結果より、デンドライト状導電性微粒子を使用することで、従来形状の導電性微粒子よりも加熱プレス後の横方向への染み出しが少ない事がわかる。また、縦方向への接続抵抗Ａが従来形状の導電性微粒子と比べて、デンドライト状導電性微粒子を用いることにより特性が優れることが明らかである。さらには、デンドライト状導電性微粒子を使用した導電性シートは、屈曲性に優れることが確認できた。 From the results of Table 1A and Table 1B, it can be seen that by using dendritic conductive fine particles, there is less oozing in the lateral direction after heat pressing than the conductive fine particles of the conventional shape. Further, it is apparent that the connection resistance A in the vertical direction is superior in characteristics by using dendritic conductive fine particles as compared with the conductive fine particles having the conventional shape. Furthermore, it has been confirmed that a conductive sheet using dendritic conductive fine particles is excellent in flexibility.
　＜実施例１４＞
　デンドライト状導電性微粒子として、平均粒子径Ｄ９０が２５μｍ、平均粒子径Ｄ５０が１３μｍの銀を用いて導電層を作製した。熱硬化性樹脂としては、ウレタン樹脂（トーヨーケム社製）を用い、デンドライト状導電性微粒子（Ｂ）と熱硬化性樹脂の比率は、樹脂１００重量部に対してデンドライト状導電性微粒子を２５０重量部とし、乾燥膜厚が１０μｍになるように、厚み１００μｍの表面を剥離処理したポリエチレンテレフタレートフィルム上に、バーコーターを用いて塗工し、１００℃で３分乾燥させて導電層を得た。上記の導電層の片面に絶縁層としてウレタン樹脂（トーヨーケム社製）を用い、乾燥膜厚が１５μｍになるように塗工・乾燥して、総厚２５μｍの絶縁層を有する電磁波シールドフィルムを得た。 <Example 14>
As dendritic conductive fine particles the average particle diameter D 90 of 25 [mu] m, an average particle diameter D 50 was prepared a conductive layer by a silver 13 .mu.m. As the thermosetting resin, a urethane resin (manufactured by Toyochem) is used, and the ratio of the dendritic conductive fine particles (B) to the thermosetting resin is 250 parts by weight of the dendritic conductive fine particles with respect to 100 parts by weight of the resin. Then, it was coated on a polyethylene terephthalate film having a surface of 100 μm peel-treated so that the dry film thickness was 10 μm using a bar coater, and dried at 100 ° C. for 3 minutes to obtain a conductive layer. Using an urethane resin (manufactured by Toyochem Co., Ltd.) as an insulating layer on one side of the conductive layer, coating and drying were performed so that the dry film thickness was 15 μm, and an electromagnetic wave shielding film having an insulating layer with a total thickness of 25 μm was obtained. .
　＜実施例１５～１７＞
　実施例１５～１７は、導電性微粒子と平均粒子径Ｄ９０と平均粒子径Ｄ５０との部分を表２Ａに示す原料に代えた他は実施例１と同様に行い、電磁波シールドフィルムを得た。 <Examples 15 to 17>
Examples 15 to 17 were carried out in the same manner as in Example 1 except that the conductive fine particles, the average particle diameter D 90, and the average particle diameter D 50 were replaced with the raw materials shown in Table 2A to obtain an electromagnetic wave shielding film. .
　＜実施例１８＞
　デンドライト状導電性微粒子（Ｂ）として、表２Ａの材料を用い、熱硬化性樹脂（Ａ）として、ウレタン樹脂（トーヨーケム社製）を用いて導電層を作製した。デンドライト状導電性微粒子（Ｂ）と熱硬化性樹脂（Ａ）の比率は、樹脂１００重量部に対してデンドライト状導電性微粒子を２５０重量部とし、乾燥膜厚が１０μｍになるように、厚み１００μｍの表面を剥離処理したポリエチレンテレフタレートフィルム上に、バーコーターを用いて塗工し、１００℃３分乾燥させて導電性シートを得た。上記の導電性シートの片面に絶縁層としてウレタン樹脂（トーヨーケム社製）を用い、乾燥膜厚が８μｍになるように塗工・乾燥して、総厚１８μｍの絶縁層を有する電磁波フィールドフィルムを得た。 <Example 18>
A conductive layer was prepared using the materials shown in Table 2A as the dendritic conductive fine particles (B) and a urethane resin (manufactured by Toyochem) as the thermosetting resin (A). The ratio of the dendritic conductive fine particles (B) to the thermosetting resin (A) is such that the dendritic conductive fine particles are 250 parts by weight with respect to 100 parts by weight of the resin, and the thickness is 100 μm so that the dry film thickness is 10 μm. On the polyethylene terephthalate film whose surface was peeled, coating was performed using a bar coater and dried at 100 ° C. for 3 minutes to obtain a conductive sheet. Using an urethane resin (manufactured by Toyochem Co., Ltd.) as an insulating layer on one side of the above conductive sheet, coating and drying to obtain a dry film thickness of 8 μm, an electromagnetic field film having an insulating layer with a total thickness of 18 μm is obtained. It was.
　＜実施例１９＞
　デンドライト状導電性微粒子として、表２Ａの材料を用いて導電性シートを作製した。熱硬化性樹脂としては、ウレタン樹脂（トーヨーケム社製）を用い、デンドライト状導電性微粒子（Ｂ）と熱硬化性樹脂の比率は、樹脂１００重量部に対してデンドライト状導電性微粒子を２５０重量部とし、乾燥膜厚が１０μｍになるように、厚み１００μｍの表面を剥離処理したポリエチレンテレフタレートフィルム上に、バーコーターを用いて塗工し、１００℃で３分乾燥させて導電性シートを得た。上記の導電性シートの片面に絶縁層としてウレタン樹脂（トーヨーケム社製）を用い、乾燥膜厚が２５μｍになるように設けて、総厚３５μｍの絶縁層を有する電磁波シールドフィルムを得た。 <Example 19>
A conductive sheet was produced using the materials shown in Table 2A as dendritic conductive fine particles. As the thermosetting resin, a urethane resin (manufactured by Toyochem) is used, and the ratio of the dendritic conductive fine particles (B) to the thermosetting resin is 250 parts by weight of the dendritic conductive fine particles with respect to 100 parts by weight of the resin. Then, it was coated on a polyethylene terephthalate film having a 100 μm thick surface peel-treated so that the dry film thickness was 10 μm, and dried at 100 ° C. for 3 minutes to obtain a conductive sheet. A urethane resin (manufactured by Toyochem Co., Ltd.) was used as an insulating layer on one side of the conductive sheet, and a dry film thickness of 25 μm was provided to obtain an electromagnetic wave shielding film having an insulating layer with a total thickness of 35 μm.
　＜実施例２０＞
　実施例１８で得られた導電性シート表面を、ロールプレス機を使用して３ＭＰaの圧力がかかるようにプレ加圧した。その後、プレ加圧した導電性シート面に、絶縁層としてウレタン樹脂（トーヨーケム社製）を乾燥膜厚が１０μｍになるように塗工・乾燥することで総厚２０μｍの絶縁層付き導電性シートを得た。 <Example 20>
The surface of the conductive sheet obtained in Example 18 was pre-pressurized using a roll press so that a pressure of 3 MPa was applied. After that, a conductive sheet with an insulating layer having a total thickness of 20 μm is formed by applying and drying urethane resin (manufactured by Toyochem) as an insulating layer on the pre-pressurized conductive sheet surface so that the dry film thickness becomes 10 μm. Obtained.
　＜実施例２１、２２＞
　プレ加圧する圧力を、それぞれ１０ＭＰa、４０ＭＰaに変更した以外は、実施例２０と同様にして絶縁層付き導電性シートを得た。 <Examples 21 and 22>
A conductive sheet with an insulating layer was obtained in the same manner as in Example 20 except that the prepressurizing pressure was changed to 10 MPa and 40 MPa, respectively.
　＜比較例１１～１５＞
　表２Ｂに示す導電性微粒子を用いて、実施例１４～１８と同様の方法で、導電層と絶縁層とを有する電磁波シールドフィルムを得た。 <Comparative Examples 11 to 15>
Using the conductive fine particles shown in Table 2B, an electromagnetic wave shielding film having a conductive layer and an insulating layer was obtained in the same manner as in Examples 14 to 18.
　表２Ａ，表２Ｂのデンドライト銀、デンドライト銅粉、フレーク状銀、球状銀に関しては、福田金属箔粉工業社製を使用した。 For the dendrite silver, dendrite copper powder, flaky silver, and spherical silver in Tables 2A and 2B, those manufactured by Fukuda Metal Foil Powder Industry Co., Ltd. were used.
　表２Ａ，表２Ｂのデンドライト銀コート銅粉は、福田金属箔粉工業社製のデンドライト銅粉を使用し、以下の条件で銀被覆処理を行うことで、銅の核９０重量％、銀被覆層１０重量％のデンドライト銀コート銅粉を得た。 The dendrite silver-coated copper powders in Tables 2A and 2B use dendrite copper powders manufactured by Fukuda Metal Foil Powder Industry Co., Ltd., and are coated with silver under the following conditions. A 10% by weight dendrite silver-coated copper powder was obtained.
＜染み出し性評価＞
　各実施例、及び各比較例に電磁波シールドフィルムを、実施例１～１３、比較例1～４と同様の方法により、染み出し量を測定した。評価基準は、前述した基準と同様とした。 <Exudation evaluation>
For each example and each comparative example, the electromagnetic wave shielding film was measured for the amount of seepage by the same method as in Examples 1 to 13 and Comparative Examples 1 to 4. Evaluation criteria were the same as those described above.
＜屈曲性＞
　幅６ｍｍ、長さ１２０ｍｍの実施例、及び比較例の電磁波シールドフィルムを、実施例１～１３、比較例1～４において説明した屈折性評価と同様の方法により評価した。評価基準は、前述した基準と同様とした。以下の通りである。 <Flexibility>
The electromagnetic shielding films of the example of 6 mm width and 120 mm length and the comparative example were evaluated by the same method as the refractive evaluation described in Examples 1 to 13 and Comparative Examples 1 to 4. Evaluation criteria were the same as those described above. It is as follows.
＜絶縁信頼性＞
　幅１００ｍｍ、長さ１００ｍｍの実施例１１～１６及び比較例１１～１５の電磁波シールドフィルムを用意し、１５０℃、３０分間、２．０ＭＰａの条件で加熱プレス処理をした。絶縁層に、三菱化学社製のＨｉｒｅｓｔａ－ＵＰ（ＭＣＰ－ＨＴ４５０）という表面抵抗試験機のＴＹＰＥ　ＵＲＳを使用し、印圧電圧が１００Ｖの条件下で１分間を接触させたときの１分間後の絶縁信頼性を評価した。評価基準は以下の通りである。
　◎：１×１０７Ω/□以上
　○：１×１０７Ω/□未満、１×１０４Ω/□以上
　×：１×１０４Ω/□未満 <Insulation reliability>
The electromagnetic wave shielding films of Examples 11 to 16 and Comparative Examples 11 to 15 having a width of 100 mm and a length of 100 mm were prepared and subjected to heat press treatment at 150 ° C. for 30 minutes and 2.0 MPa. After 1 minute when contact was made for 1 minute under the condition that the printing voltage was 100V, using HIPE-UP (MCP-HT450) surface resistance tester TYPE URS made by Mitsubishi Chemical Co., Ltd. The insulation reliability was evaluated. The evaluation criteria are as follows.
◎: 1 × 10 7 Ω / □ or more ○: Less than 1 × 10 7 Ω / □, 1 × 10 4 Ω / □ or more ×: Less than 1 × 10 4 Ω / □
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　表２Ａ、表２Ｂの結果より、デンドライト状導電性微粒子の平均粒子径Ｄ９０が導電層の膜厚に対して０．５～３倍の範囲内に特定することで、従来形状の導電性微粒子よりも加熱プレス後の横方向への導電層の染み出しが少ない事がわかる。また、優れた屈曲性を示しているとともに、高い絶縁信頼性も実現できたことが確認された。 From the results shown in Tables 2A and 2B, the average particle diameter D 90 of the dendritic conductive fine particles is specified within the range of 0.5 to 3 times the film thickness of the conductive layer, so that the conductive fine particles of the conventional shape are obtained. It can be seen that there is less seepage of the conductive layer in the lateral direction after hot pressing. Moreover, it was confirmed that it showed excellent flexibility and high insulation reliability.
　以上の実施例を含む実施形態に関し、更に以下の付記を開示する。
（付記１）
　少なくとも熱硬化性樹脂（Ａ）と、デンドライト状導電性微粒子（Ｂ）とを含む導電層を有する導電性シートであって、前記導電性シートを１５０℃、２Ｍｐａ、３０分間の条件で加熱プレスした後の厚みが、加熱プレス前の厚みを１００としたときに３０～９５であることを特徴とする導電性シート。
（付記２）
　少なくとも絶縁層と導電層とを有する電磁波シールドフィルムであって、
前記導電層が少なくとも熱硬化性樹脂（Ａ）とデンドライト状導電性微粒子（Ｂ）を含み、デンドライト状導電性微粒子（Ｂ）の平均粒子径Ｄ９０が導電層の膜厚に対して０．５～３倍の範囲内にあることを特徴とする電磁波シールドフィルム。
（付記３）
　デンドライト状導電性微粒子（Ｂ）の平均粒子径Ｄ５０が３～５０μｍであることを特徴とする付記２記載の電磁波シールドフィルム。
（付記４）
　デンドライト状導電性微粒子（Ｂ）が銅を含む核と、銀被覆層を含み、
前記銀被覆層が、デンドライト状導電性微粒子（Ｂ）１００重量％中、１～４０重量％の割合であることを特徴とする付記２又は３に記載の電磁波シールドフィルム。
（付記５）
　導電層の厚みを１００とするときに、絶縁層の厚みが５０～２００であることを特徴とする付記２～４のいずれかに記載の電磁波シールドフィルム。 The following additional notes are further disclosed with respect to the embodiment including the above examples.
(Appendix 1)
A conductive sheet having a conductive layer containing at least a thermosetting resin (A) and dendritic conductive fine particles (B), wherein the conductive sheet was heated and pressed under conditions of 150 ° C., 2 Mpa, 30 minutes. A conductive sheet characterized in that the subsequent thickness is 30 to 95 when the thickness before hot pressing is 100.
(Appendix 2)
An electromagnetic wave shielding film having at least an insulating layer and a conductive layer,
The conductive layer contains at least a thermosetting resin (A) and dendritic conductive fine particles (B), and the average particle diameter D90 of the dendritic conductive fine particles (B) is 0.5 to 0.5 with respect to the thickness of the conductive layer. An electromagnetic wave shielding film characterized by being in a range of 3 times.
(Appendix 3)
The electromagnetic wave shielding film as set forth in appendix 2, wherein the dendritic conductive fine particles (B) have an average particle diameter D50 of 3 to 50 μm.
(Appendix 4)
The dendritic conductive fine particles (B) include a nucleus containing copper and a silver coating layer,
Item 4. The electromagnetic wave shielding film according to item 2 or 3, wherein the silver coating layer is in a proportion of 1 to 40% by weight in 100% by weight of the dendritic conductive fine particles (B).
(Appendix 5)
5. The electromagnetic wave shielding film according to any one of appendices 2 to 4, wherein when the thickness of the conductive layer is 100, the insulating layer has a thickness of 50 to 200.
　この出願は、２０１１年５月３１日に出願された日本出願特願２０１１－１２１１８８、及び２０１１年１０月２５日に出願された日本出願特願２０１１－２３３５２８を基礎とする優先権を主張し、その開示の全てをここに取り込む。 This application claims priority based on Japanese Patent Application No. 2011-121188 filed on May 31, 2011 and Japanese Patent Application No. 2011-233528 filed on October 25, 2011. The entire disclosure is incorporated herein.
　本発明に係る導電性シートは、加熱プロセス等のプロセスにおいて、導電層の染み出しを最小限に低減できるので、プリント配線板やフレキシブルプリント板をはじめとする基板などの被着体全般に貼着せしめて利用する用途に好適に適用できる。特に、導電性シートの染み出しが問題となる電子部品用途への貼着に特に威力を発揮する。本発明に係る導電性シートは、絶縁層、支持層、接着層、あるいは別の機能を有するフィルム等と積層して利用することも可能である。 Since the conductive sheet according to the present invention can reduce the seepage of the conductive layer to a minimum in a process such as a heating process, the conductive sheet is attached to all adherends such as printed wiring boards and flexible printed boards. It can be suitably applied to applications that are used at least. In particular, it is particularly effective for sticking to the use of electronic parts where the bleeding of the conductive sheet is a problem. The conductive sheet according to the present invention can be used by being laminated with an insulating layer, a support layer, an adhesive layer, a film having another function, or the like.
　１：ポリイミドフィルム
　２：銅箔回路
　３：カバーフィルム
　４：スルーホール
　５：導電性シート
　６：ステンレス
　７：絶縁層 1: Polyimide film 2: Copper foil circuit 3: Cover film 4: Through hole 5: Conductive sheet 6: Stainless steel 7: Insulating layer

Claims (12)

  1. 　熱硬化性樹脂（Ａ）と、
    　デンドライト状導電性微粒子（Ｂ）と、を少なくとも含む導電層を具備し、
    　前記導電層の厚みが、（ｉ）１５０℃、２ＭＰａ、３０分間の条件で、被着体と加熱プレスした後の厚みが、加熱プレス前の当該導電層の厚みを１００としたときに３０以上、９５以下の範囲になるもの、及び（ｉｉ）前記デンドライト状導電性微粒子（Ｂ）の平均粒子径Ｄ９０が、当該導電層の厚みに対して０．５倍以上、３倍以下の範囲になるもの、の少なくとも一方を満たし、
    　前記デンドライト状導電性微粒子（Ｂ）の平均粒子径Ｄ５０が３μｍ以上、５０μｍ以下であって、かつ、前記デンドライト状導電性微粒子（Ｂ）を前記導電層中に５０重量％以上、９０重量％以下の範囲で含有する導電性シート。     A thermosetting resin (A);
    A dendritic conductive fine particle (B), and a conductive layer containing at least,
    When the thickness of the conductive layer is (i) 150 ° C., 2 MPa, 30 minutes, the thickness after hot pressing with the adherend is 30 or more when the thickness of the conductive layer before hot pressing is 100 , those in the range of 95 or less, and the average particle diameter D 90 of (ii) said dendritic conductive fine particles (B) is 0.5 times or more the thickness of the conductive layer, in the range of 3 times or less Satisfy at least one of
    The average particle diameter D 50 of 3μm or more of the dendritic conductive particles (B), there is 50μm or less, and, the dendritic conductive fine particles (B) in the conductive layer 50 wt% or more, 90 wt% A conductive sheet contained in the following range.
  2. 　前記デンドライト状導電性微粒子（Ｂ）の平均粒子径Ｄ９０は、前記平均粒子径Ｄ５０の１．５倍以上、５倍以下である請求項１記載の導電性シート。 The average particle diameter D 90 is the average particle diameter D 50 1.5 times or more, the conductive sheet according to claim 1, wherein is 5 times or less of the dendrite conductive fine particles (B).
  3. 　前記デンドライト状導電性微粒子（Ｂ）のタップ密度が０．８ｇ／ｃｍ３以上、２．５ｇ／ｃｍ３以下であることを特徴とする請求項１または２記載の導電性シート。 3. The conductive sheet according to claim 1, wherein a tap density of the dendritic conductive fine particles (B) is 0.8 g / cm 3 or more and 2.5 g / cm 3 or less.
  4. 　前記デンドライト状導電性微粒子（Ｂ）の見掛密度が０．４ｇ／ｃｍ３以上、１．５ｇ／ｃｍ３以下であることを特徴とする請求項１～３のいずれか１項に記載の導電性シート。 The conductive material according to any one of claims 1 to 3, wherein an apparent density of the dendritic conductive fine particles (B) is 0.4 g / cm 3 or more and 1.5 g / cm 3 or less. Sex sheet.
  5. 　前記デンドライト状導電性微粒子（Ｂ）は、見掛密度ＡＤとタップ密度ＴＤの比率が、ＡＤ／ＴＤ＝０．３～０．９であることを特徴とする請求項１～４のいずれか１項に記載の導電性シート。 5. The dendrite-like conductive fine particle (B) has an apparent density AD / tap density TD ratio of AD / TD = 0.3 to 0.9. The conductive sheet according to item.
  6. 　前記デンドライト状導電性微粒子（Ｂ）は、核が銅であり、その表面に銀被覆層を有し、
    　前記銀被覆層が、デンドライト状導電性微粒子（Ｂ）１００重量％中、１重量％以上、４０重量％以下の割合であることを特徴とする請求項１～５のいずれか１項に記載の導電性シート。     The dendritic conductive fine particles (B) have a nucleus of copper and a silver coating layer on the surface thereof.
    The silver coating layer according to any one of claims 1 to 5, wherein the silver coating layer is in a ratio of 1% by weight to 40% by weight in 100% by weight of the dendritic conductive fine particles (B). Conductive sheet.
  7. 　前記導電層は、塗工した後、２．５ＭＰａ～５０ＭＰａの圧力を加えて形成された層であることを特徴とする請求項１～６のいずれか１項に記載の導電性シート。 The conductive sheet according to any one of claims 1 to 6, wherein the conductive layer is a layer formed by applying a pressure of 2.5 MPa to 50 MPa after coating.
  8. 　前記導電層上に、絶縁層が積層されている請求項１～７のいずれか１項に記載の導電性シート。 The conductive sheet according to any one of claims 1 to 7, wherein an insulating layer is laminated on the conductive layer.
  9. 　前記導電層の厚みを１００とするときに、前記絶縁層の厚みが５０～２００であることを特徴とする請求項８に記載の導電性シート。 The conductive sheet according to claim 8, wherein when the thickness of the conductive layer is 100, the thickness of the insulating layer is 50 to 200.
  10. 　電磁波シールドフィルムとして用いる請求項８又は９に記載の導電性シート。 The conductive sheet according to claim 8 or 9, which is used as an electromagnetic wave shielding film.
  11. 　請求項１～１０のいずれか１項に記載の導電性シートが貼着せしめられた電子部品。 An electronic component to which the conductive sheet according to any one of claims 1 to 10 is adhered.
  12. 　平均粒子径Ｄ５０が３μｍ以上、５０μｍ以下のデンドライト状導電性微粒子（Ｂ）と、熱硬化性樹脂（Ａ）とを含む導電性樹脂組成物を、剥離性シートに塗工して、前記デンドライト状導電性微粒子（Ｂ）を５０重量％以上、９０重量％以下の範囲で含有する導電層を形成し、
    　前記導電層に２.５ＭＰａ以上、５０ＭＰａ以下の圧力を加える工程を含む導電性シートの製造方法。     A dendrite-like conductive fine particle (B) having an average particle diameter D 50 of 3 μm or more and 50 μm or less and a thermosetting resin (A) are coated on a peelable sheet, and the dendrites Forming a conductive layer containing the conductive fine particles (B) in the range of 50 wt% or more and 90 wt% or less,
    A method for producing a conductive sheet, comprising a step of applying a pressure of 2.5 MPa or more and 50 MPa or less to the conductive layer.
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