JP2016183335A - Conductive Adhesive, Conductive Adhesive Sheet and Electromagnetic Wave Shielding Sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive adhesive which can form a conductive adhesive sheet having high adhesiveness on a plated surface and high heat resistance and also having excellent connection reliability, and provide a conductive adhesive sheet and an electromagnetic wave shielding sheet.SOLUTION: An conductive adhesive comprises a thermosetting resin, a curing agent, conductive fine particles, and heterocyclic amine, where the heterocyclic amine has a 5 membered or 6 membered heterocycle, and the curing agent has at least one curing agent (X) selected from the group consisting of isocyanate compound, aziridine compound, and metal chelate compound.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a conductive adhesive that can be suitably used for a printed wiring board and the like, and an application technique thereof.

  In recent years, flexible and flexible flexible printed wiring boards (hereinafter referred to as FPCs) have become indispensable in electronic devices such as mobile phones, video cameras, and notebook computers that are rapidly becoming smaller and thinner. . In addition, as electronic devices have higher performance, built-in signal wirings are becoming narrower and higher in frequency, and countermeasures against electromagnetic wave noise are becoming increasingly important. Therefore, it is common to incorporate an electromagnetic shielding material that shields or absorbs electromagnetic noise generated from signal wiring and electronic modules into the FPC.

The FPC connector part and electronic component mounting part should be used with a reinforcing plate (for example, a stainless steel plate, an aluminum plate, a copper plate, an iron plate, etc.) pasted with a conductive adhesive to provide electromagnetic shielding and mechanical strength. There are many. In some cases, the reinforcing plate is plated with gold, nickel, palladium, or the like in order to enhance conductivity or prevent corrosion (Patent Documents 1 and 2). For this reason, the conductive adhesive used for bonding the reinforcing plate is required not only for the polyimide film but also for the adhesion with the plated surface to be processed on the reinforcing plate.
In addition, the electromagnetic shielding sheet used by being attached to the FPC has enhanced the electromagnetic shielding performance by connecting the FPC ground wiring and a conductive layer formed of a conductive adhesive, and is processed in the ground portion. Adhesiveness with a gold plating surface is required (Patent Document 3).

JP2013-041869A International Publication No. 2014/132951 International Publication No. 2014/010524 International Publication No. 2016/088127 JP 2008-069237 A JP 2011-86598 A Special table 2013-510220 gazette JP 2007-294918 A

  However, in the FPC manufacturing process, in order to mount electronic components, the entire FPC including the solder portion formed by printing or coating in advance is heated to about 230 to 280 ° C. by infrared reflow or the like to melt the solder and wire the electronic components. A solder reflow process for bonding to a plate is common. In this solder reflow process, if the adhesive force between the conductive adhesive layer and the plating surface is insufficient, there is a problem that foaming or peeling occurs at the adhesive interface, resulting in poor appearance and reduced connection reliability.

  Patent Documents 4 to 8 disclose electromagnetic wave shielding adhesive films in which the conductive adhesive layer contains a thermosetting resin, an epoxy-based curing agent, conductive particles, and a heterocyclic amine compound. However, such a conventional conductive adhesive layer is excellent in electromagnetic wave shielding properties and does not achieve both adhesion to FPC and heat resistance.

  An object of the present invention is to provide a conductive adhesive, a conductive adhesive sheet, and an electromagnetic wave shielding sheet that can form a conductive adhesive sheet having high adhesion to a plated surface and high heat resistance and excellent connection reliability. .

  The conductive adhesive of the present invention contains a thermosetting resin, a curing agent, conductive fine particles, and a heterocyclic amine.

  According to the present invention described above, the conductive adhesive containing a heterocyclic amine improves the adhesive force due to the improved affinity for the plating surface, and has heat resistance that is less likely to cause defects on the adhesive interface even after the solder reflow process. It was.

  According to the present invention, it is possible to provide a conductive adhesive, a conductive adhesive sheet, and an electromagnetic wave shielding sheet that can form a conductive adhesive sheet having high adhesion to a plated surface and high heat resistance and excellent connection reliability.

Sectional drawing which shows the layer structure of an electromagnetic wave shield sheet. Sectional drawing which shows the A aspect of a printed wiring board. Sectional drawing which shows the B aspect of a printed wiring board. Explanatory drawing of the measurement sample of the connection resistance value of a conductive adhesive sheet. Explanatory drawing of the measurement sample of the connection resistance value of an electromagnetic wave shield sheet.

  First, terms used in the present invention will be described. Sheet is synonymous with film and tape. The adherend refers to the other party to which the sheet is attached.

  The conductive adhesive of the present invention contains a thermosetting resin, a curing agent, conductive fine particles, and a heterocyclic amine. The conductive adhesive can be used as a conductive adhesive sheet by, for example, coating on a release sheet to form a conductive adhesive layer (sometimes simply referred to as “conductive layer”). The conductive adhesive sheet can be used as an electromagnetic wave shielding sheet by further including an insulating layer.

<Thermosetting resin>
The thermosetting resin is a resin having a plurality of reactive functional groups capable of crosslinking reaction with a curing agent.
Examples of the functional group include a hydroxyl group, a phenolic hydroxyl group, a carboxyl group, an amino group, an epoxy group, an oxetanyl group, an oxazoline group, an oxazine group, an aziridine group, a thiol group, an isocyanate group, a blocked isocyanate group, and a silanol group. .
Examples of the thermosetting resin having the above functional group include acrylic resin, maleic acid resin, polybutadiene resin, polyester resin, condensation type polyester resin, addition type polyester resin, melamine resin, polyurethane resin, polyurethane urea resin, and epoxy resin. Oxetane resin, phenoxy resin, polyimide resin, polyamide resin, phenol resin, alkyd resin, amino resin, polylactic acid resin, oxazoline resin, benzoxazine resin, silicone resin, fluorine resin, and the like. Among these, polyurethane resin, polyurethane urea resin, epoxy resin, addition type polyester resin, polyimide resin, polyamide resin, and polyamideimide resin are preferable from the viewpoint of surface resistance value and abrasion resistance.

In the present invention, a thermoplastic resin can be used in combination with the thermosetting resin.
Thermoplastic resins include polyolefin resins that do not have curable functional groups, vinyl resins, styrene / acrylic resins, diene resins, terpene resins, petroleum resins, cellulose resins, polyamide resins, polyurethane resins, polyester resins, A polycarbonate resin, a polyimide resin, a fluororesin, etc. are mentioned.
The polyolefin resin is preferably a homopolymer or copolymer such as ethylene, propylene, and α-olefin compound. Specific examples include polyethylene propylene rubber, olefinic thermoplastic elastomer, α-olefin polymer, and the like.
The vinyl resin is preferably a polymer obtained by polymerization of vinyl ester such as vinyl acetate or a copolymer of vinyl ester and olefin compound such as ethylene. Specific examples include ethylene-vinyl acetate copolymer and partially saponified polyvinyl alcohol.
The styrene / acrylic resin is preferably a homopolymer or copolymer composed of styrene, (meth) acrylonitrile, acrylamides, (meth) acrylic acid esters, maleimides and the like. Specific examples include syndiotactic polystyrene, polyacrylonitrile, acrylic copolymer, ethylene-methyl methacrylate copolymer, and the like.
The diene resin is preferably a homopolymer or copolymer of a conjugated diene compound such as butadiene or isoprene and a hydrogenated product thereof. Specific examples include styrene-butadiene rubber and styrene-isoprene block copolymer. The terpene resin is preferably a polymer composed of terpenes or a hydrogenated product thereof. Specific examples include aromatic modified terpene resins, terpene phenol resins, and hydrogenated terpene resins.
The petroleum resin is preferably a dicyclopentadiene type petroleum resin or a hydrogenated petroleum resin. The cellulose resin is preferably a cellulose acetate butyrate resin. The polycarbonate resin is preferably bisphenol A polycarbonate. The polyimide resin is preferably a thermoplastic polyimide, a polyamideimide resin, or a polyamic acid type polyimide resin.

<Curing agent>
The curing agent has a plurality of functional groups capable of reacting with the functional group of the thermosetting resin, such as an epoxy compound, an acid anhydride group-containing compound, an isocyanate compound, an aziridine compound, an amine compound, and a phenol compound. And metal chelate compounds.
A hardening | curing agent can be used individually or in combination with 2 or more types.

  The conductive adhesive of the present invention is characterized by containing at least one curing agent (X) selected from the group consisting of an isocyanate compound, an aziridine compound, and a metal chelate compound as a curing agent.

  0.1-100 weight part is preferable with respect to 100 weight part of thermosetting resins, and, as for the usage-amount of a hardening | curing agent, 1-50 weight part is more preferable.

  The content of the entire curing agent including the curing agent (X) is preferably 2 to 70 parts by weight, more preferably 100 parts by weight with respect to the heterocyclic amine, from the viewpoint of improving adhesive strength and heat resistance. Is 3 to 60 parts by weight.

Moreover, it is preferable to contain a hardening | curing agent (X) and another hardening agent, and it is preferable at the point which is excellent in heat resistance and adhesive force that another hardening | curing agent is an epoxy compound.
Specifically, a combination of an aziridine compound and an epoxy compound, a metal chelate compound and an epoxy compound is preferable, and a combination of a metal chelate compound and an epoxy compound is more preferable. By using together as described above, heat resistance and adhesive strength are improved.

  Thus, when using together hardening | curing agent (X) with an epoxy compound, it is preferable that content of an epoxy compound is 250-2000 weight part with respect to 100 weight part of hardening | curing agents (X), 300-1000 weight. Part.

[Curing agent (X)]
The curing agent (X) is an isocyanate compound, an aziridine compound, or a metal chelate compound, and contains a heterocyclic amine compound and a curing agent (X), so that it has excellent adhesion and connection reliability. Adhesive.
The curing agent (X) can be used alone or in combination of two or more.
Among these, from the viewpoint of improving adhesive strength and connection reliability, an aziridine compound or a metal chelate compound is preferable, and a metal chelate compound is more preferable.
It is also preferable to use an aziridine compound and a metal chelate compound in combination.

  The content of the curing agent (X) is preferably 1 to 100% by weight in the total amount (100% by weight) of the curing agent in the conductive adhesive, and is more preferable in terms of excellent adhesive strength and heat resistance. 2 to 90% by weight.

  The content of the curing agent (X) is preferably 10 to 400 parts by weight, more preferably 100 parts by weight with respect to 100 parts by weight of the heterocyclic amine, from the viewpoint of further improving heat resistance and adhesive strength. It is 25 to 350 parts by weight, particularly preferably 45 to 300 parts by weight.

(Isocyanate compound)
Examples of the isocyanate compound include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, Polyisocyanate compounds such as polymethylene polyphenyl isocyanate, adducts of these polyisocyanate compounds and polyol compounds such as trimethylolpropane, burettes and isocyanurates of these polyisocyanate compounds, and these polyisocyanate compounds and known polyisocyanates. Ether polyol and polyester Le polyols, acrylic polyols, polybutadiene polyols, adducts, etc. and polyisoprene polyol and the like.

(Aziridine compound)
Examples of the aziridine compound include 2,2′-bishydroxymethylbutanol tris [3- (1-aziridinyl) propionate], 4,4′-bis (ethyleneiminocarbonylamino) diphenylmethane, and the like.

(Metal chelate compound)
The metal chelate compound is a compound composed of a metal and an organic substance, and reacts with a functional group of the curable resin to form a crosslink. Although the kind of metal chelate compound is not specifically limited, An organic aluminum compound, an organic titanium compound, an organic zirconium compound, etc. are mentioned. The bond between the metal and the organic substance may be a metal-oxygen bond and is not limited to a metal-carbon bond. In addition, the bonding mode between the metal and the organic substance may be any of a chemical bond, a coordinate bond, and an ionic bond.

  As the organoaluminum compound, an aluminum chelate compound is preferable. Examples of the aluminum chelate compound include ethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate), alkyl acetoacetate aluminum diisopropylate, aluminum monoacetylacetonate bis (ethyl acetoacetate), aluminum tris (acetylacetate), Aluminum monoacetyl acetate bis (ethyl acetoacetate), aluminum di-n-butoxide monomethyl acetoacetate, aluminum diisobutoxide monomethyl acetoacetate, aluminum di-sec-butoxide monomethyl acetoacetate, aluminum isopropylate, mono sec-butoxy aluminum diisopropyl Rate, aluminum-sec-butylate, al Bromide ethylate, and the like.

  As the organic titanium compound, a titanium chelate compound is preferable. Examples of the titanium chelate compound include titanium acetylacetonate, titanium tetraacetylacetonate, titanium ethylacetoacetate, titanium octylene glycolate, titanium ethylacetoacetate, titanium-1.3-propanedioxybis (ethylacetoacetate), Polytitanium acetylacetylacetonate, tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetraoctyl titanate, dark amyl titanate, tetra tertiary butyl titanate, tetrastearyl titanate, titanium isostearate, tri-n-butoxy titanium Monostearate, di-i-propoxytitanium distearate, titanium stearate, di-i-propoxytitanium diisostearate Include (2-n-butoxycarbonyl benzoyloxy) tributoxy titanium.

  As the organic zirconium compound, a zirconium chelate compound is preferable. Zirconium chelate compounds include, for example, zirconium tetraacetylacetonate, zirconium tributoxyacetylacetonate, zirconium monobutoxyacetylacetonate bis (ethylacetoacetate), zirconium dibutoxybis (ethylacetoacetate), zirconium tetraacetylacetonate, normal Examples thereof include propyl zirconate, normal butyl zirconate, zirconium stearate, and zirconium octylate. Among these, an organic titanium compound is preferable from the viewpoints of thermosetting reactivity and heat resistance after curing.

[Other curing agents]
Examples of other curing agents include epoxy compounds, acid anhydride group-containing compounds, amine compounds, and phenol compounds.
When other curing agents are used in combination, it is preferably an epoxy compound, and the combined use of the curing agent (X) and the epoxy compound can further improve the heat resistance and adhesive strength.

(Epoxy compound)
As the epoxy compound, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin, alicyclic epoxy resin and the like are preferable. Bisphenol A type epoxy resin and alicyclic epoxy resin are particularly preferable from the viewpoint of connection resistance value and adhesive strength.

<Conductive fine particles>
In the present invention, the conductive fine particles are preferably gold, platinum, silver, copper, nickel, aluminum, iron, tin and indium, and alloys thereof. Further, the conductive fine particles may be composite fine particles provided with a core and a coating layer covering the surface of the core.

  As the conductive fine particles, composite fine particles having a coating layer in which a metal or a resin is used as a core and the surface of the core is coated are preferable from the viewpoint of cost reduction. Here, the core is preferably selected appropriately from inexpensive nickel, silica, copper and alloys thereof, and resins. The coating layer may be a material that is more conductive than the core, and is preferably a conductive metal or a conductive polymer. Examples of the conductive metal include gold, platinum, silver, nickel, manganese, indium, and alloys thereof. Examples of the conductive polymer include polyaniline and polyacetylene. Among these, silver is preferable from the viewpoints of price and conductivity.

  The metal of the coating layer is preferably formed in a ratio of 1 to 40 parts by weight, more preferably 5 to 20 parts by weight with respect to 100 parts by weight of the core. When the core is coated with the metal in the above range, for example, when the copper core is coated with silver, the price of the conductive fine particles can be further reduced while maintaining the conductivity.

  The shape of the conductive fine particles is not limited as long as desired conductivity is obtained. The shape is preferably, for example, spherical, flake-like, leaf-like, dendritic, plate-like, needle-like or grape-like. Among these, flakes, leaves, and dendrites are preferable because high conductivity can be obtained with a small addition amount. The leaf-shaped conductive fine particles are fine particles in which at least one of notches and branched leaves is formed in the outer edge shape. Further, the flaky conductive fine particles are fine particles having no cuts and no branching leaves in the outer edge shape.

  1-100 micrometers is preferable and, as for the average particle diameter of electroconductive fine particles, 3-50 micrometers is more preferable. When the average particle diameter is in the range of 1 to 100 μm, the conductivity is further improved. The average particle size in the present invention is obtained by measuring each conductive fine particle with a tornado dry powder sample module using a laser diffraction / scattering particle size distribution measuring device LS 13320 (manufactured by Beckman Coulter). D50 average particle size, and the cumulative value in the cumulative particle size distribution is 50%. In the measurement, the refractive index of the fine particles was set to 1.6.

  The conductive fine particles are preferably blended in an amount of 30 to 1500 parts by weight, more preferably 50 to 1000 parts by weight with respect to 100 parts by weight of the thermosetting resin. By blending 30 to 1500 parts by weight, it becomes easy to achieve both conductivity and adhesiveness.

<Heterocyclic amine>
The conductive adhesive of the present invention includes a heterocyclic amine having a 5-membered ring or a 6-membered ring. By containing the heterocyclic amine having a 5-membered ring or 6-membered ring and the curing agent (X), the adhesive force to the plated surface can be improved.
Among them, a heterocyclic amine having a 5-membered ring is preferable.
The heterocyclic amine preferably contains 1 to 4 nitrogen atoms, more preferably 1 to 3 and even more preferably 2 to 3 in one ring structure. The heterocyclic amine may have a ring structure that can resonate with the heterocyclic ring, such as a benzene ring (for example, benzotriazole). Moreover, the heterocyclic amine may contain elements other than carbon and nitrogen in the ring, and may have a substituent. The acid dissociation constant (pKa) of the heterocyclic amine is preferably _{3 to} 15 (20 ° C. in H ₂ O). The heterocyclic amine preferably contains two or more elements other than carbon (for example, nitrogen, oxygen, sulfur) in the ring structure.
The heterocyclic amine is preferably a planar structure (eg, triazole, thiazole, melamine, imidazole). When the heterocyclic amine has a planar structure, the adhesion to the plated surface is further improved.
The heterocyclic amine preferably has a conjugated bond.

  The heterocyclic amine is preferably compounded with the compound alone in the conductive adhesive, or blended with the polymer in a form bonded to the polymer, or a combination thereof. As the polymer to which the heterocyclic amine can be bonded, the thermosetting resin and thermoplastic resin described above can be used. Amino resins are preferred.

Examples of the heterocyclic amine include imidazole, pyrazole, oxazole, thiazole, imidazoline, pyrazine, piperazine, triazole, triazine, melamine, benzimidazole, benzotriazole, benzothiazole, and purine skeleton.
From the viewpoint of heat resistance, a piperazine, triazine, melamine, or benzotriazole skeleton is preferable.
More preferred are triazine, melamine, and benzotriazole skeletons.

  The molecular weight of the heterocyclic amine is preferably 30 to 500, more preferably 50 to 400.

These compounds can be represented by the following general formulas (1) to (17). Among these, general formulas (12) to (16) are preferable in that they can be excellent in heat resistance.
Particularly preferred are heterocyclic amines of the general formulas (12) to (15).

General formula (1)

General formula (2)

General formula (3)

General formula (4)

General formula (5)

General formula (6)

General formula (7)

General formula (8)

General formula (9)

General formula (10)

Formula (11)

Formula (12)

Formula (13)

General formula (14)

General formula (15)

Formula (16)

Formula (17)

In the general formulas (1) to (17), X1 is a hydrogen atom or a hydrocarbon group, and the hydrocarbon group may have a side chain or a functional group. Functional groups include, for example, hydroxyl group, phenolic hydroxyl group, methoxymethyl group, carboxyl group, amino group, epoxy group, oxetanyl group, oxazoline group, oxazine group, aziridine group, thiol group, isocyanate group, blocked isocyanate group, blocked A carboxyl group, a silanol group, etc. are mentioned. Further, it may be a metal salt such as lithium, sodium or potassium.
Among these, a carboxyl group, a thiol group, an epoxy group, and an amino group are preferable.

In the general formulas (1) to (17), R1 to R8 are a hydrogen atom, a hydrocarbon group, or a functional group, and the hydrocarbon group may have a side chain or a functional group. Functional groups include, for example, hydroxyl group, phenolic hydroxyl group, methoxymethyl group, carboxyl group, amino group, epoxy group, oxetanyl group, oxazoline group, oxazine group, aziridine group, thiol group, isocyanate group, blocked isocyanate group, blocked A carboxyl group, a silanol group, etc. are mentioned.
Among these, a hydrogen atom, a hydrocarbon group, a carboxyl group, a thiol group, an epoxy group, and an amino group are preferable.

  The number of functional groups other than hydrogen atoms of the heterocyclic amine is preferably 1 to 3.

  Examples of commercially available heterocyclic amines include “Cureazole 2P4MHZ” [general formula (1)] manufactured by Shikoku Kasei Co., Ltd., “3,5-dimethylpyrazole” [general formula (2)] manufactured by Otsuka Chemical Co., Ltd. “1,2,3-triazole” [general formula (6)] manufactured by Otsuka Chemical Co., Ltd., “3 mercapto-1,2,4-triazole” manufactured by Otsuka Chemical Co., Ltd., “CDA-1” manufactured by ADEKA Co., Ltd. [General Formula (7)] “Tosoh Co., Ltd.” “Ethylaminopiperazine” [General Formula (8)]; BUDIT 313 "," BUDIT 313G "," BUDIT 315 "," TSH "manufactured by Kawaguchi Chemical Co., Ltd. [General formula (12)] “TEPIC-G”, “TEPIC-S”, “TEPIC-SP”, “TEPIC-SS” [general formula (13)] manufactured by Nissan Chemical Industries, Ltd. “Sandant MB” manufactured by Sanshin Chemical Industries, Ltd. [general Formula (14)], “CBT-1”, “BT-120”, “BT-LX”, “TT-LX”, “TT-LYK”, “JC-400”, “JF” manufactured by Johoku Chemical Industry Co., Ltd. -77 "," JF-79 "," JF-80 "," JF-83 "," JF-832 "," JAST-500 "," SEETEC TT-R "," SEETEC TA- "manufactured by Sipro Kasei Co., Ltd. "268" [general formula (15)], "Sunseller M", "Sanbit NG", "Sunbit ABT", "Sanbit PBT" [general formula (16)] manufactured by Sanshin Chemical Industry Co., Ltd. Is available.

  It is preferable that 0.5-20 weight part is mix | blended with respect to 100 weight part of thermosetting resins, and, as for a heterocyclic amine, 1-10 weight part is more preferable. By blending 0.5 to 20 parts by weight, adhesive strength, heat resistance, and connection reliability are further improved.

  The compounding amount of the heterocyclic amine with respect to the conductive fine particles is preferably 0.1 to 20 parts by weight, and more preferably 0.2 to 8 parts by weight with respect to 100 parts by weight of the conductive fine particles. A connection resistance value and heat resistance improve by being 0.1-20 weight part.

  The conductive adhesive of the present invention may contain a solvent, a heat stabilizer, a pigment, a dye, a tackifier resin, a plasticizer, a coupling agent, an ultraviolet absorber, an antifoaming agent, a leveling adjusting agent, and the like as optional components. it can.

  The conductive adhesive can be obtained by stirring and mixing the materials described so far. For the stirring, for example, a known stirring device such as a disperse mat or a homogenizer can be used.

<Conductive adhesive sheet>
The conductive adhesive sheet of the present invention is a sheet provided with a conductive adhesive layer (also referred to as a conductive layer) formed by applying a conductive adhesive onto a peelable sheet. In addition, the surface which is not in contact with the peelable sheet of the conductive adhesive layer can usually prevent adhesion of foreign matters such as dust and dust by attaching another peelable sheet until just before use.

  A known coating method can be used for coating the conductive adhesive. Specifically, for example, gravure coating method, kiss coating method, die coating method, lip coating method, comma coating method, blade method, roll coating method, knife coating method, spray coating method, bar coating method, spin coating method, and dip. A coating method or the like is preferable. Moreover, after coating, drying is performed as necessary. For drying, a known dryer such as a hot air oven or an infrared heater can be used.

  The thickness of the conductive adhesive layer is preferably 3 to 70 μm, and more preferably 5 to 65 μm. By being in the range of 3 to 70 μm, the heat resistance and the connection reliability are further improved by further improving the conductivity and the adhesive force.

  When the conductive adhesive sheet of the present invention is stored, the thermosetting resin and the curing agent are present in an unreacted state, and the thermosetting resin and the curing agent react with each other when the substrate is overheat-pressed. Alternatively, when the conductive adhesive contains two types of curing agents, there is also an embodiment in which one curing agent reacts during the formation of the conductive adhesive sheet and the other curing agent reacts during the thermocompression bonding.

  The conductive adhesive sheet of the present invention can be used for applications that require electrical conductivity. Specifically, when the reinforcing plate to be bonded is a conductive material, the conductive material can function as an electromagnetic wave shielding layer by being electrically connected to the FPC ground circuit. The conductive adhesive sheet of the present invention can be preferably used for a liquid crystal display such as a touch panel, a mobile phone incorporating these, a smartphone, a tablet terminal and the like. In addition, the said description does not prevent use other than the said use of a conductive adhesive sheet.

<Electromagnetic wave shield sheet>
The electromagnetic wave shielding sheet of the present invention has a first aspect including an insulating layer and a conductive layer, and a second aspect including an insulating layer, a metal layer, and a conductive layer.
The conductive layer of the electromagnetic wave shielding sheet of the present invention was formed using the above-described conductive adhesive in both the first and second aspects.

  In the case of the first aspect, the conductive layer is an isotropic conductive layer. In the case of the second aspect, the conductive layer can be appropriately selected from an isotropic conductive layer and an anisotropic conductive layer. However, when the anisotropic conductive layer is used, the content of conductive fine particles can be suppressed, so that cost reduction is facilitated. . In addition, isotropic conductivity means conducting in the vertical direction (longitudinal direction) and the horizontal direction (plane direction) when the electromagnetic wave shielding sheet is placed horizontally. On the other hand, anisotropic conductivity means conducting in the vertical direction (longitudinal direction) when the electromagnetic wave shielding sheet is placed horizontally. The isotropic conductivity can be obtained by a known method such as a method using flaky or dendritic conductive fine particles. The anisotropic conductivity can be obtained by a method using spherical or dendritic conductive fine particles. Note that isotropic conductivity is obtained when the conductive layer contains a large amount of dendritic conductive fine particles. Further, when the conductive layer contains a small amount of dendritic conductive fine particles, anisotropic conductivity can be obtained.

  The production of the first aspect can be obtained by bonding a conductive layer produced in advance as already described and an insulating layer produced separately as described later.

<Insulating layer>
The insulating layer is obtained by molding an insulating resin composition containing a thermosetting resin and a curing agent. As the thermosetting resin and the curing agent, the thermosetting resin and the curing agent already described for the conductive adhesive can be used.

  The insulating resin composition can further improve the visibility of characters printed on the insulating layer by including a black colorant. The black colorant is preferably a black color pigment and a mixed colorant containing a plurality of pigments such as red, green, blue, yellow, purple, cyan and magenta. The mixed colorant can obtain black color by subtractive color mixing of a plurality of pigments.

  Insulating resin compositions include pigments and dyes other than black colorants as necessary, silane coupling agents, antioxidants, tackifier resins, plasticizers, ultraviolet absorbers, antifoaming agents, leveling regulators, It can be appropriately selected from fillers, flame retardants and the like.

  The insulating resin composition can be obtained by mixing and stirring a thermosetting resin and a curing agent. For the stirring, a known stirring device can be used, and a disperse mat or a homogenizer is preferable.

  The insulating layer can be formed, for example, by applying an insulating resin composition onto a peelable sheet. Alternatively, the insulating resin composition can be formed by extruding it into a sheet by an extruder such as a T-die.

  Coating may be performed by the method described in the formation of the conductive adhesive layer.

  The thickness of the insulating layer can be appropriately designed according to the use, but is preferably about 0.5 μm to 25 μm, and more preferably about 2 μm to 15 μm.

  The production of the second aspect can be produced, for example, by forming a conductive layer on a peelable sheet, laminating a metal layer on the surface of the conductive layer, and laminating a separately prepared insulating layer on the metal layer. The creation may be performed by reversing the conductive layer and the insulating layer.

The metal layer is preferably, for example, a conductive metal foil such as aluminum, copper, silver, or gold, more preferably copper, silver, or aluminum, and even more preferably copper from the viewpoint of shielding properties and cost. As the copper, for example, a rolled copper foil or an electrolytic copper foil is preferably used. When the thickness of the metal layer is pursued, a copper foil obtained by etching the rolled copper foil or an electrolytic copper foil is more preferable. In the case of a metal foil, the thickness is preferably 0.1 to 10 μm, and more preferably 0.5 to 5 μm.
In addition to the metal foil, the metal layer may be formed by vacuum deposition, sputtering, CVD, MO (metal organic), plating, or the like. Among these, vacuum deposition and plating are preferable in consideration of mass productivity. The thickness of the metal layer other than the metal foil is usually about 0.005 to 5 μm. In addition, as for the thickness of a metal vapor deposition film, 0.1-3 micrometers is preferable. The thickness of the sputtering film is preferably 10 to 1000 nm.

In addition to the above layer structure, the electromagnetic wave shielding sheet of the present invention can also be laminated with other functional layers other than conductivity and insulation.
The other functional layer is a layer having functions such as hard coat property, water vapor barrier property, oxygen barrier property, low dielectric constant, high dielectric constant property, and heat resistance.

  In addition, when the thermosetting resin is used, the electromagnetic wave shielding sheet of the present invention exists in a state where the crosslinkable functional group of the thermosetting resin and the functional group of the curing agent are partially reacted (semi-cured state). preferable. And when using an electromagnetic wave shield sheet, for example, it piles on or attaches to FPC (flexible printed wiring board), and after that, it is often hardened by a thermocompression bonding process, and desired adhesive strength is often obtained.

  The peelable sheet preferably uses a paper or plastic substrate, and a sheet having a known release treatment on one side of the substrate or a pressure sensitive adhesive layer instead of the release treatment is used. It is a formed sheet.

  Note that the electromagnetic wave shielding sheet is often stored in a state where a peelable sheet is pasted until just before use, in order to facilitate protection and handling of the conductive layer or the insulating layer.

  The electromagnetic wave shielding sheet of the present invention can be used for various applications where electromagnetic waves need to be shielded. For example, rigid printed wiring boards can be used for flexible printed wiring boards, COFs, TABs, flexible connectors, liquid crystal displays, touch panels, and the like. Moreover, it can also be used as a member for shielding electromagnetic waves from a case of a personal computer, a building material such as a wall of a building material and a window glass, a vehicle, a ship, and an aircraft.

  If the 2nd aspect provided with the electromagnetic wave shielding sheet of the printed wiring board of this invention is demonstrated, the electromagnetic wave shielding sheet and the wiring board containing a cover coat layer, a signal wiring, and an insulating base material are provided.

The aspect (A aspect) provided with the electroconductive adhesive sheet and the aspect (B aspect) provided with the electromagnetic wave shielding sheet are preferable for the printed wiring board of the present invention.
About A aspect, the printed wiring board 4 is provided with the wiring board 7, the metal reinforcement board 6, and the electroconductive adhesive layer 5, as shown in FIG. Further, the conductive adhesive layer 5 can be bonded to the insulating substrate 10 of the wiring board 7. Needless to say, the mode of the printed wiring board is not limited to that shown in FIGS.

  The embodiment of the printed wiring board 4 will be further described. The wiring board 7 has the strength required for the printed wiring board 4 by mounting the electronic component 14 on the surface that is in contact with the insulating substrate 10 and that faces the metal reinforcing plate 6. By providing the metal reinforcing plate 6, it is possible to prevent damage to the solder bonding portion or the insulating base material 10 when a force such as bending is applied to the printed wiring board 1. Further, the conductive adhesive 5 can shield electromagnetic waves from the upper side to the lower side of the printed wiring board 4.

Examples of the metal plate 6a of the metal reinforcing plate 6 include conductive metals such as gold, silver, copper, iron, and stainless steel. Among these, stainless steel is preferable in terms of strength, cost, and chemical stability as a reinforcing plate. The thickness of the metal reinforcing plate 6 is generally about 0.04 to 1 mm.
The metal reinforcing plate 6 can also be provided with a plating layer 6b of gold, nickel, palladium or the like on the surface thereof. By providing the plating layer 6b, oxidation and corrosion of the metal reinforcing plate 6 can be prevented, and higher conductivity stability can be obtained. Although not shown, the metal reinforcing plate 6 may not have the plating layer 6b.

  The wiring board 7 includes insulating layers 8a and 8b, adhesive layers 9a and 9b, a ground wiring 11, a signal wiring 12, and an insulating substrate 10. Further, the wiring board 7 includes a cylindrical or mortar-shaped hole called a via 14 (Via). The ground wiring and the signal wiring are collectively referred to as a wiring circuit.

  The insulating layers 8a and 8b are also called cover coat layers and contain at least a resin. Examples of the resin include acrylic resins, epoxy resins, polyester resins, urethane resins, ethane urethane resins, silicone resins, polyamide resins, polyimide resins, amideimide resins, and phenol resins. The resin can be appropriately selected from a thermoplastic resin, a thermosetting resin, and an ultraviolet curable resin, and is preferably a thermosetting resin in terms of heat resistance. These resins can be used alone or in combination of two or more. The thickness of the insulating layers 8a and 8b is usually about 5 to 50 μm.

  Examples of the adhesive layers 9a and 9b include thermosetting resins such as acrylic resins, epoxy resins, polyester resins, urethane resins, silicone resins, and amide resins. Examples of the curing agent used for the thermosetting resin include an epoxy curing agent, an isocyanate curing agent, and an alidiline curing agent. The adhesive layers 9a and 9b are used for bonding the insulating layers 8a and 8b to the insulating base material 9 including the ground wiring 11 and the wiring circuit 12, and have insulating properties. The thickness of the adhesive layers 9a and 9b is usually about 1 to 20 μm.

  The ground wiring 11 and the signal wiring 12 are generally formed by etching a metal foil such as copper or by printing a conductive paste. Although not shown, the wiring board 7 can have a plurality of ground wirings and signal wirings. The ground wiring is a circuit that maintains a ground potential, and the signal wiring is a circuit that transmits an electrical signal to an electronic component or the like. The thickness of the ground wiring 7 and the signal wiring 8 is usually about 5 to 50 μm, respectively.

The insulating base material 10 is an insulating film such as polyimide, polyamideimide, polyferene sulfide, polyethylene terephthalate, and polyethylene naphthalate, and is a base material for the wiring board 7. The insulating substrate 10 is preferably polyferene sulfide and polyimide when the reflow process is performed, and is preferably polyethylene terephthalate when the reflow process is not performed. The thickness of the insulating substrate 10 is usually about 5 to 100 μm. When the printed wiring board is a rigid wiring board, the insulating substrate 10 is preferably glass epoxy.
The insulating substrate 9 is

  The via 14 is formed by etching, laser, or the like in order to expose a part of the circuit pattern appropriately selected from the ground wiring 11 and the signal wiring 12. According to FIG. 2, a part of the ground wiring 11 is exposed by the via 14, and the ground wiring 11 and the metal reinforcing plate 6 are electrically connected through the conductive adhesive layer 5. The diameter of the via 14 is usually about 0.5 to 2 μm.

The method for producing a printed wiring board of the present invention needs to include a step of crimping at least the wiring board 7, the conductive adhesive layer 5, and the metal reinforcing plate 6. Examples of the crimping include a method of crimping the wiring board 7 and the electromagnetic wave shielding sheet, then laminating and bonding the conductive adhesive layer 5 and the metal reinforcing plate 6, and then mounting electronic components. It is not limited. In this invention, what is necessary is just to provide the process of crimping | bonding the wiring board 7, the electroconductive adhesive layer 5, and the metal reinforcement board 6, and another process can be suitably changed according to the structure thru | or use aspect of a printed wiring board. In the case where the conductive adhesive layer 5 contains a thermosetting resin, the pressure bonding is particularly preferably performed simultaneously from the viewpoint of acceleration of curing. On the other hand, even when the conductive adhesive layer 5 includes a thermoplastic resin, it is preferable to heat the adhesive adhesive layer 5 because the adhesion is likely to become strong. The heating is preferably 130 to 210 ° C, more preferably 140 to 200 ° C. The pressure bonding is preferably ² to 120 kg / cm ² , more preferably ³ to 100 kg / cm ² .
As the crimping apparatus, a flat plate crimping machine or a roll crimping machine can be used. However, when a flat plate crimping machine is used, it is preferable because a certain pressure can be applied for a certain period of time. The crimping time is not particularly limited as long as the printed circuit board 6, the conductive adhesive layer 5, and the metal reinforcing plate 6 are in close contact with each other, but is usually about 30 minutes to 2 hours.

The aspect (B aspect) provided with the electromagnetic wave shielding sheet of the printed wiring board of this invention is demonstrated with reference to FIG.
The electromagnetic wave shielding sheet includes an insulating layer 1, a metal layer 3, and a conductive layer 2. Although not shown, the electromagnetic wave shielding sheet preferably includes the insulating layer 1 and the conductive layer 2.

  The cover coat layers 8a and 8b are insulating materials that cover the signal wiring of the wiring board and protect it from the external environment. The cover coat layers 8a and 8b are preferably a thermosetting or ultraviolet curable solder resist or a photosensitive coverlay film, and more preferably a photosensitive coverlay film for fine processing.

The signal wiring includes a ground wiring 11 for grounding and a signal wiring 12 for sending an electric signal to the electronic component. Both are generally formed by etching a copper foil.
When the insulating substrate 10 is a flexible printed wiring board (FPC), a bendable plastic such as polyester, polycarbonate, polyimide, or polyphenylene sulfide is preferable, and polyimide is more preferable. When the wiring board is a rigid wiring board, the constituent material of the insulating substrate 10 is preferably glass epoxy. By providing the insulating base material 10 like these, the wiring board can have high heat resistance.

  Generally, the thermocompression bonding between the electromagnetic wave shielding sheet and the wiring board 7 is performed under conditions of a temperature of about 150 to 190 ° C., a pressure of about 1 to 3 MPa, and a time of about 1 to 60 minutes. The conductive layer 2 and the cover coat layers 8 a and 8 b are brought into close contact with each other by thermocompression bonding, and the conductive layer 2 flows and fills the via 14, thereby establishing conduction with the ground wiring 11. Further, when a thermosetting resin is used, the thermosetting resin and the curing agent react by thermocompression bonding. In order to accelerate curing, post-curing may be performed at 150 to 190 ° C. for 30 to 90 minutes after thermocompression bonding. In addition, an electromagnetic wave shield sheet may be called an electromagnetic wave shield layer after thermocompression bonding.

  The printed wiring board of the present invention is preferably mounted on an electronic device such as a notebook PC, a mobile phone, a smartphone, or a tablet terminal in addition to a liquid crystal display, a touch panel, or the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited at all by these. In addition, a part means a weight part and% means weight%. Mw represents a weight average molecular weight.

The materials used in the examples are shown below.
Conductive fine particles: Silver-coated copper powder (average particle size 11.0 μm Dendritic composite fine particles using copper for the core and silver for the coating layer, manufactured by Fukuda Metal Foil Powder Industry Co., Ltd.)
・ Metal chelate compound: “Orgatics TC100” (Matsumoto Fine Chemical Co., Ltd.)
Isocyanate compound: “Duranate 17B-60PX” (manufactured by Asahi Kasei Chemicals)
Aziridine compound: “Chemite PZ-33” (manufactured by Nippon Shokubai)
Epoxy compound: Multifunctional epoxy resin “JER604” (Mitsubishi Chemical Corporation)
Heterocyclic amine (1): Carboxybenzotriazole Heterocyclic amine (2): 1,2,3-triazole Heterocyclic amine (3): 2-phenyl-4-methyl-5-hydroxymethylimidazole Heterocycle Amine (4): Tris (2,3-epoxypropyl) isocyanurate / heterocyclic amine (5): Melamine polyphosphate (CBC)
• Heterocyclic amine (6): Ethylaminopiperazine • Heterocyclic amine (7): 2-mercaptobenzothiazole • Chain amine: Stearylamine • Electrolytic copper foil: “3EC-M1S-HTE” (thickness 9 μm) (Mitsui (Made by Metal Mining)
Adherent 1: “Electrolytic gold plating sheet” (0.3 μm gold plating layer, 1 μm nickel plating layer, 18 μm rolled copper foil layer, 25 μm adhesive layer, and 25 μm polyimide layer in this order) ) Made by Taiyo Kogyo Co., Ltd .: Substrate 2: “SUS304-1 / 2H NiP2.0UP (W)” (200 μm thick stainless steel plate with 2 μm nickel plating layer), manufactured by Sylvania
Adherent 3: Stainless steel plate with a thickness of 200 μm having a palladium plating layer of 0.02 μm Two-layer CCL: “Esperflex” (8 μm rolled copper foil layer and 38 μm polyimide layer laminate Sumitomo Metal Mining Co., Ltd. Made)

<Synthesis of thermosetting polyamide resin>
A reaction vessel equipped with a stirrer, thermometer, dropping device, reflux condenser, and gas introduction tube was charged with 104.1 parts of dimer acid having an acid value of 194 KOH mg / g and 25.2 parts of norbornane diamine, so that the temperature of heat generation was constant. Stir until. When the temperature was stabilized, the mixture was heated to 110 ° C. Heating was performed 30 minutes after confirming the start of the dehydration reaction, and the reaction temperature was 120 ° C. Thereafter, the dehydration reaction was continued by heating to 230 ° C. so that the reaction temperature increased at a rate of 10 ° C. in 30 minutes. After reaching 230 ° C., the temperature was maintained and the reaction was continued for 3 hours. Next, the pressure was reduced and a vacuum of about 2 kPa was maintained for 1 hour, followed by cooling. An amide resin containing a carboxyl group having a nonvolatile content of 50% was obtained by diluting with appropriate amounts of toluene and isopropyl alcohol. The obtained amide resin had Mw = 15000, an acid value of 18 mgKOH / g, and Tg of 17 ° C.

<Preparation of conductive adhesive sheet>
Example 1
As a thermosetting resin, 20 parts of epoxy compound, 400 parts of conductive fine particles, 3 parts of metal chelate compound, 5 parts of heterocyclic amine compound (1), solvent (toluene) with respect to 100 parts of the obtained thermosetting polyamide resin ) Was added and stirred and mixed with a disper to obtain a conductive adhesive having a nonvolatile content of 40%. The resulting conductive adhesive is coated on a peelable film (50 μm thick polyethylene phthalate) so that the thickness after drying is 20 μm, and dried at 100 ° C. for 2 minutes to provide a conductive adhesive layer A conductive adhesive sheet was prepared.

(Examples 2 to 11, Comparative Examples 1 and 2)
Except having changed the raw material and compounding quantity of Example 1 as shown in Table 1, it carried out similarly to Example 1, and produced the conductive adhesive sheet of Examples 2-11 and Comparative Examples 1 and 2, respectively.

<Production of electromagnetic shielding sheet>
(Example 12)
"Process 1-1"
An insulating resin composition was obtained by adding 20 parts of an epoxy compound, 3 parts of a metal chelate compound, and toluene to 100 parts of a thermosetting polyamide resin and stirring and mixing with a disper. The obtained insulating resin composition was applied to a peelable film using a bar coater so that the thickness after drying was 9 μm, and dried by heating at 100 ° C. for 2 minutes to produce an insulating layer.
"Step 1-2"
To 100 parts of thermosetting polyamide resin, 20 parts of epoxy compound, 600 parts of conductive fine particles, 3 parts of metal chelate compound, 5 parts of heterocyclic amine compound (1) and toluene are added and mixed by stirring with a disper. A resin composition was obtained. The obtained conductive resin composition was applied to a peelable film (polyethylene phthalate having a thickness of 75 μm) using a bar coater so that the thickness after drying was 10 μm, and dried by heating at 100 ° C. for 2 minutes. Thus, an isotropic conductive layer was produced.
"Process 1-3"
The obtained insulating layer and the obtained conductive layer are bonded using a laminator at a temperature of 80 ° C., a pressure of 2 MPa, and a line speed of 2 m / min to produce an electromagnetic wave shielding sheet 1 having the insulating layer and the conductive layer. did.

(Examples 13-20, Comparative Examples 3-5)
Except having changed the raw material and compounding quantity of Example 12 as shown in Table 1, it carried out similarly to Example 12, and produced the electromagnetic wave shield sheet of Examples 13-20 and Comparative Examples 3-5, respectively.

(Example 21)
"Process 2-1"
By adding 20 parts of an epoxy compound, 70 parts of conductive fine particles, 3 parts of a metal chelate compound and 5 parts of a heterocyclic amine compound (1) to 100 parts of a thermosetting polyamide resin, adding toluene and stirring and mixing with a disper. A conductive resin composition was obtained. The obtained conductive resin composition was applied to a peelable film (thickness 75 μm) using a bar coater so that the thickness after drying was 10 μm, and dried by heating at 100 ° C. for 2 minutes. A positively conductive layer was produced.
"Process 2-2"
The insulating layer produced in the same manner as in the above “Step 1-2” and the roughened surface of the copper foil are bonded using a laminator at a temperature of 80 ° C., a pressure of 2 MPa, and a line speed of 2 m / min. Yeah. The copper foil surface of the laminate and the obtained conductive layer were bonded together under the same conditions as above to produce an electromagnetic wave shield sheet provided with an insulating layer, a metal layer, and a conductive layer.

(Examples 22 to 29, Comparative Examples 6 and 7)
The electromagnetic wave shields of Examples 22 to 29 and Comparative Examples 6 and 7, respectively, were carried out in the same manner as in Example 21, except that the raw materials and blending amounts of the conductive resin composition of Example 21 were changed as shown in Table 2. A sheet was produced.

  The following physical properties were evaluated about the obtained electroconductive adhesive sheet and electromagnetic wave shielding sheet.

"Evaluation of conductive adhesive sheet"
(1) Adhesive strength
A conductive adhesive sheet having a width of 10 mm and a length of 100 mm was prepared and attached to the gold-plated surface of the adherend 1 by a roll-type laminate. Next, the peelable sheet of the conductive adhesive sheet was peeled off and bonded to the polyimide surface of the two-layer CCL to obtain a laminate. The laminate is pressure-bonded under conditions of 170 ° C., 2 MPa, and 5 minutes, and then heated in an electric oven at 160 ° C. for 60 minutes to laminate “two layers CCL / conductive adhesive layer / adhered body 1”. Got the body. With respect to the laminate, the adhesive force (N / cm) between the conductive adhesive layer and the metal plating surface was measured under an atmosphere of 23 ° C. and a relative humidity of 50% under a pulling speed of 50 mm / min and a peel angle of 90 °. . About Example 2, 3, it measured by the same method except having used the adherends 2 and 3 instead of the adherend 1, respectively. The results were evaluated according to the following criteria.
A: “Adhesive strength of 6 (N / cm) or more” is excellent.
○: “Adhesion strength of 4.5 (N / cm) or more and less than 6 (N / cm)” Good Δ: “Adhesion strength of 3 (N / cm) or more and less than 4.5 (N / cm)” Practical use Possible x: “Adhesive strength of less than 3 (N / cm)” impractical

(2) Heat resistance The same laminated body as the laminated body used by the measurement of the said adhesive strength was prepared. Next, the laminate was floated on molten solder at 260 ° C. for 1 minute with the polyimide surface of the two-layer CCL facing down. The laminated body was taken out from the molten solder, the appearance of the conductive adhesive layer was visually confirmed, and evaluated according to the following criteria. For the evaluation, 5 samples were used.
A: Bubbles were not generated in all samples. Excellent ○: Air bubbles were generated in the sample. Good Δ: Air bubbles were generated in 2 to 3 samples. Practical use x: Bubbles were generated in 4 samples or more. Impractical

(3) Connection resistance value A conductive adhesive sheet having a width of 20 mm and a length of 50 mm was prepared as Sample 25. 4 (4), the exposed conductive adhesive layer 25 of the sample 25 is not electrically connected to the FPC (12.5 μm-thick polyimide film 21) separately produced. A copper foil circuit 22A and a copper foil circuit 22B having a thickness of 18 μm are formed, and a cover film 23 having a through hole 24 having a thickness of 37.5 μm and a diameter of 1.6 mm with an adhesive is formed on the copper foil circuit 22A. The laminated wiring board) was bonded together by a roll type laminate. Next, the peelable film is peeled off from the conductive adhesive layer 25, a stainless steel plate 26 having a thickness of 3 mm is placed on the exposed conductive adhesive layer 25, and pressure-bonded for 1 hour under conditions of 170 ° C. and 2 MPa. Layer 25 was cured. After pressure bonding, heat treatment was performed three times at a peak temperature of 260 ° C. using a reflow furnace “UNI-5016” (manufactured by Nippon Anton Co., Ltd.). The connection resistance value between the copper foil circuit 22A and the copper foil circuit 22B of this laminate was measured using a four-point probe of “Lorester GP” manufactured by Mitsubishi Chemical. 4 (2) is a sectional view taken along the line DD ′ of FIG. 4 (1), and FIG. 4 (3) is a sectional view taken along the line CC ′ of FIG. 4 (1). Similarly, FIG. 4 (5) is a DD ′ sectional view of FIG. 4 (4), and FIG. 4 (6) is a CC ′ sectional view of FIG. 4 (4). The evaluation criteria for the connection resistance value are as follows.
A: Connection resistance value less than 100 mΩ Excellent.
○: Connection resistance value 100 mΩ or more and less than 250 mΩ Good △: Connection resistance value 250 mΩ or more and less than 500 mΩ Practical use ×: Connection resistance value 500 mΩ or more Practical use impossible

  The results are shown in Table 1.

"Evaluation of electromagnetic wave seal sheet"
(4) Adhesive strength Prepare an electromagnetic shielding sheet with a width of 10 mm and a length of 100 mm, and peel off the peelable sheet on the conductive layer side and attach the exposed conductive layer to the gold-plated surface of the adherend 1 with a roll laminate. I attached. Next, the peelable sheet on the insulating layer side is peeled off, and a polyimide film (Toray DuPont Co., Ltd. “Kapton 200EN”) having a thickness of 50 μm is attached to the exposed insulating layer via a 25 μm thick adhesive sheet (manufactured by Toyochem). A sample was obtained by pasting. Then, in order to protect the sample, both sides of the sample are sandwiched between two 125 μm-thick polyimide films (Toray DuPont Co., Ltd. “Kapton 500H”) and subjected to a pressure-bonding treatment at 170 ° C., 2 MPa for 30 minutes. A laminate of “adherent 1 / electromagnetic wave shield sheet / 25 μm adhesive sheet / 50 μm polyimide film” was obtained. In order to measure the adhesive force between the conductive layer and the metal plating surface, the laminate was subjected to a peel test at a peel rate of 90 ° at a pulling speed of 50 mm / min in an atmosphere of 23 ° C. and 50% relative humidity. The strength (N / cm) was measured. The results were evaluated according to the following criteria.
A: “Adhesive strength of 6 (N / cm) or more” is excellent.
○: “Adhesion strength of 4.5 (N / cm) or more and less than 6 (N / cm)” Good Δ: “Adhesion strength of 3 (N / cm) or more and less than 4.5 (N / cm)” Practical use Possible x: “Adhesive strength of less than 3 (N / cm)” impractical

(5) Heat resistance An electromagnetic wave shielding sheet is prepared with a width of 30 mm and a length of 40 mm, the peelable sheet on the conductive layer side is peeled off, and the exposed conductive layer is rolled against the gold-plated surface of the adherend 1. A sample was obtained by laminating. Thereafter, in order to protect the sample, it was sandwiched between two polyimide films having a thickness of 125 μm and subjected to pressure-bonding treatment at 170 ° C. and 2 MPa for 30 minutes to obtain a laminate of “adhered body 1 / electromagnetic wave shield sheet”. . Next, the release film on the insulating layer side of the laminate was peeled off and floated on molten solder at 260 ° C. for 1 minute with the polyimide surface of the adherend 1 facing down. The appearance of the laminate taken out from the molten solder was visually confirmed and evaluated according to the following criteria. For the evaluation, 5 samples were used.
A: Bubbles were not generated in all samples. Excellent ○: Air bubbles were generated in the sample. Good Δ: Air bubbles were generated in 2 to 3 samples. Practical use x: Bubbles were generated in 4 samples or more. Impractical

(6) Connection resistance value An electromagnetic wave shielding sheet having a width of 20 mm and a length of 50 mm was prepared as Sample 35. 5 (4), the peelable film is peeled off from the sample 35, and the exposed conductive layer 35b is electrically connected to the FPC (polyimide film 31 having a thickness of 12.5 μm) separately produced. A copper foil circuit 32A and a copper foil circuit 32B having a thickness of 18 μm are formed, and a cover having an adhesive and a through hole 34 having a thickness of 37.5 μm and a diameter of 1.6 mm is formed on the copper foil circuit 32A. The film 33 was laminated with a roll type laminate. Next, in order to protect the sample, the peelable film is peeled off from the insulating layer 35a, and a 125 μm-thick polyimide film (Toray DuPont “Kapton 500H”) is layered on the exposed insulating layer 35a, under conditions of 170 ° C. and 2 MPa. The conductive layer 25 was cured by pressing for 30 minutes. After pressure bonding, heat treatment was performed three times at a peak temperature of 260 ° C. using a reflow furnace “UNI-5016” (manufactured by Nippon Anton Co., Ltd.). The connection resistance value between the copper foil circuit 22A and the copper foil circuit 22B of this laminate was measured using a four-point probe of “Lorester GP” manufactured by Mitsubishi Chemical. 5 (2) is a cross-sectional view taken along the line DD ′ of FIG. 5 (1), and FIG. 5 (3) is a cross-sectional view taken along the line CC ′ of FIG. 5 (1). Similarly, FIG. 5 (5) is a DD ′ sectional view of FIG. 5 (4), and FIG. 5 (6) is a CC ′ sectional view of FIG. 5 (4).

A: Connection resistance value less than 100 mΩ Excellent.
○: Connection resistance value 100 mΩ or more and less than 250 mΩ Good △: Connection resistance value 250 mΩ or more and less than 500 mΩ Practical use ×: Connection resistance value 500 mΩ or more Practical use impossible

  The obtained results are shown in Tables 3 to 6.

DESCRIPTION OF SYMBOLS 1 Insulation layer 2 Conductive layer 3 Metal layer 4 Printed wiring board 5 Conductive adhesive layer 6 Metal reinforcement board 6a Metal plate 6b Plating layer 7 Wiring board 8a 8b Cover coat layer 9a 9b Adhesive layer 10 Insulating substrate 11 Ground wiring 12 signal wiring 13 electronic component 14 via 15 printed wiring board

Claims (9)

Including a thermosetting resin, a curing agent, conductive fine particles, and a heterocyclic amine,
The heterocyclic amine has a 5- or 6-membered heterocyclic ring;
The curing agent is
A conductive adhesive containing at least one curing agent (X) selected from the group consisting of an isocyanate compound, an aziridine compound, and a metal chelate compound.   The conductive adhesive according to claim 1, wherein the content of the curing agent (X) is 10 to 400 parts by weight with respect to 100 parts by weight of the heterocyclic amine.   The conductive adhesive according to claim 1 or 2, wherein the curing agent (X) is a metal chelate compound.   The conductive adhesive according to any one of claims 1 to 3, wherein the curing agent further contains an epoxy compound.   The conductive adhesive according to claim 1, wherein the heterocyclic amine contains 1 to 3 nitrogen atoms in one ring structure.   The electroconductive adhesive sheet formed from the electroconductive adhesive of any one of Claims 1-5.   The electromagnetic wave shield sheet provided with the insulating layer and the conductive layer formed from the conductive adhesive of any one of Claims 1-5.   The electromagnetic wave shield sheet provided with the electrically conductive layer formed from an insulating layer, a metal layer, and the electrically conductive adhesive of any one of Claims 1-5.   A printed wiring board comprising at least one sheet of the conductive adhesive sheet according to claim 6 and the electromagnetic wave shielding sheet according to any one of claims 7 and 8.