JP2014149918A - Film-like circuit connection material and circuit connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film-like circuit connection material having excellent insulation which can ensure visibility by a sensor while reducing connection resistance between circuit electrodes, and to provide a circuit connection structure using the same.SOLUTION: A film-like circuit connection material 1 has an adhesive layer 61 interposed between circuit electrodes facing each other, and interconnecting the circuit electrodes. The adhesive layer 61 contains an adhesive component 3 containing (a) a thermoplastic resin, (b) a curable material, (c) a hardener, and (d) a dye stuff, and conductive particles 5 which is a metal plating having a plastic nucleus and a metal layer covering the plastic nucleus, where the outermost layer of the metal layer contains at least one kind selected from Ni, an Ni alloy and an Ni oxide, and having an average grain size of 2.0-3.5 μm.

Description

  The present invention relates to a film-like circuit connection material and a circuit connection structure.

  Conventionally, anisotropic conductive adhesive films are known as film-like circuit connecting materials for heating and pressurizing opposing circuits to electrically connect electrodes in the pressing direction, such as epoxy adhesives and acrylics. An anisotropic conductive adhesive film in which conductive particles are dispersed in an adhesive is known. Such an anisotropic conductive adhesive film is mainly composed of a TCP (Tape Carrier Package) or COF (Chip On Flex) on which a semiconductor for driving a liquid crystal display (hereinafter referred to as “LCD”) is mounted and the LCD panel. Widely used for electrical connection or electrical connection between a TCP or COF and a printed wiring board.

  Recently, even when a semiconductor is directly mounted on an LCD panel or a printed wiring board face down, flip chip mounting, which is advantageous for thinning and narrow pitch connection, has been adopted instead of the conventional wire bonding method. Also in this flip chip mounting, an anisotropic conductive adhesive film is used as an adhesive film for circuit connection (see, for example, Patent Documents 1 to 4).

  By the way, in recent years, with the increase in COF and fine pitch of LCD modules, there is a problem that a short circuit occurs between adjacent circuit electrodes when connecting using a film-like circuit connecting material. As a countermeasure, a technique is known in which insulating particles are dispersed in an adhesive component to prevent a short circuit (see, for example, Patent Documents 5 to 9).

  When the insulating particles are dispersed in the adhesive component, there is a tendency that a decrease in the adhesive force of the film-like circuit connecting material or peeling at the interface between the substrate and the circuit connecting portion becomes a problem. For this reason, a film-like circuit connecting material is used for bonding a wiring member made of an insulating organic substance or glass to a wiring member made of at least one of silicon nitride, silicone resin, and polyimide resin. In order to reduce the internal stress based on the method of improving the adhesive force by adding silicone particles to the adhesive (see, for example, Patent Document 10) and the difference in thermal expansion coefficient after adhesion, the rubber particles are dispersed in the film-like circuit connecting material. A method is known (see, for example, Patent Document 11).

  Furthermore, as a means for preventing a short circuit between circuit electrodes, a method is known in which conductive particles whose surfaces are coated with an insulating film are dispersed in a film-like circuit connecting material (see, for example, Patent Documents 12 and 13). .

JP 59-120436 A JP-A-60-191228 JP-A-1-251787 JP-A-7-90237 JP 51-20941 A JP-A-3-29207 JP-A-4-174980 Japanese Patent No. 3048197 Japanese Patent No. 3477367 International Publication No. 01/014484 Pamphlet JP 2001-323249 A Japanese Patent No. 2779409 Japanese Patent Laid-Open No. 2001-195921

  In recent years, an indium-zinc oxide (IZO) electrode has been used instead of an indium-tin oxide (ITO) electrode as a circuit electrode of a glass substrate from the viewpoint of reducing costs. Yes. For IZO electrodes, from the viewpoint of reducing connection resistance between circuit electrodes, instead of film-like circuit connection material in which conductive particles covered with an outermost layer made of Au or the like are dispersed, Ni or Ni alloy or Ni A film-like circuit connecting material in which conductive particles covered with an outermost layer containing an oxide or the like are dispersed has been studied.

  In the TFT-LCD, it is common to form a metal circuit such as Mo or Al as a base for the above-mentioned thin film electrode. However, due to the fact that the number of parts such as driver ICs has been reduced for the purpose of cost reduction, the way of drawing a thin film circuit is very complicated. Especially in a panel using IZO electrodes, electrodes caused by circuit resistance Burning (burnt phenomenon) may occur. Therefore, a low-resistance film-like circuit connection material in which conductive particles covered with an outermost layer containing Ni, Ni alloy, Ni oxide, etc. are dispersed has attracted attention.

  When connecting a circuit using such a film-like circuit connecting material, it is broadly divided into (1) application of the film-like circuit connecting material to the substrate and peeling of the base film by heating and pressing, (2) The three steps of temporary connection of the flexible substrate to the film-like circuit connection material by heating and pressing and (3) main connection of the flexible substrate to the film-like circuit connection material by heating and pressing are performed.

  In the step (1), a CCD camera or a laser sensor is installed in the production facility in order to check whether or not the film-like circuit connecting material is stuck at a predetermined position on the substrate. However, in a film-like circuit connecting material in which conductive particles covered with an outermost layer containing Ni, Ni alloy, Ni oxide, etc. are dispersed, there is a problem that visibility when using a laser sensor is lowered, for example. Yes. Furthermore, when the transparency of the film-like circuit connection material is high, or when the thickness of the film-like circuit connection material is thin, not only the laser sensor but also the CCD camera has poor visibility, the conductive particles are made smaller, and high definition. In the case of a connection-compatible film-like circuit connection material, it has become a problem that the visibility is further significantly reduced. On the other hand, the visibility can be improved by using fine particles such as titanium oxide. However, when the particle size is large or when the dispersion state in the adhesive is poor, the aggregate is formed particularly in a high-definition circuit. As a result, there is a problem that a short circuit occurs due to clogging of the conductive particles between the circuits, so that it is difficult to use the film-like circuit connection material for high definition.

  The present invention has been made in order to solve the above-mentioned problems, and has a film-like circuit connection material that has excellent insulation and can ensure visibility by a sensor while reducing the connection resistance between circuit electrodes, and uses the same. An object of the present invention is to provide a circuit connection structure.

  The present invention relates to a film-like circuit connecting material having an adhesive layer interposed between opposing circuit electrodes to electrically connect circuit electrodes. The adhesive layer comprises (a) a thermoplastic resin, (b) a curable material, (c) a curing agent, and (d) an adhesive component containing a dye, a plastic core, and a metal that covers the plastic core. The outermost layer of the metal layer is a metal plating containing at least one selected from the group consisting of Ni, Ni alloy and Ni oxide, and the average particle size is 2.0 to 3.5 μm Conductive particles.

  When the average particle diameter of the conductive particles is 2.0 μm to 3.5 μm, a short circuit between the circuit electrodes can be suppressed even in a high-definition circuit electrode. By combining conductive particles of such an average particle size with a dye or the like, the color difference between the portion where the film-like circuit connecting material is affixed and the portion where the film-like circuit connection material is affixed is increased while reducing the connection resistance. Thus, the visibility can be ensured without depending on the type of the sensor, and the pasted state can be easily recognized.

The number of conductive particles is preferably 2000 to 15000 / mm ² when viewed from the thickness direction of the adhesive layer. In this case, a sufficient contact area can be ensured in order to obtain a good connection resistance while suppressing costs. Moreover, deterioration of insulation resistance can be suppressed.

  The circuit connection structure according to the present invention includes an adhesive layer of the film-like circuit connection material between a first circuit member having a first circuit electrode and a second circuit member having a second circuit electrode. And is obtained by electrically connecting the first circuit electrode and the second circuit electrode by heating and pressurizing them.

  In this circuit connection structure, by using the circuit connection material, the connection resistance between the circuit electrodes can be reduced without depending on the type of the circuit electrodes. Visibility can be ensured without depending on the type of sensor, and the sticking state can be easily recognized, so that connection reliability can be ensured.

  ADVANTAGE OF THE INVENTION According to this invention, sufficient visibility with a sensor is securable, reducing the connection resistance between circuit electrodes. In addition, it is easy to check the presence or absence of the adhesive layer even when the film circuit connection material is wound in a reel shape, and it is easy to check whether the circuit connection material is flowing properly after circuit connection. However, the present invention has advantageous effects.

It is a schematic cross section which shows one Embodiment of the film-form circuit connection material which concerns on this invention. It is the schematic cross section which illustrated the electroconductive particle contained in a film-form circuit connection material. 1 is a schematic cross-sectional view showing an embodiment of a circuit connection structure according to the present invention. It is a schematic cross section which shows the formation process of a circuit connection structure. It is a figure which shows the structure of the film-form circuit connection material which concerns on an Example. It is a figure which shows the structure of the film-form circuit connection material which concerns on a reference example or a comparative example. It is a figure which shows the evaluation result of a film-form circuit connection material.

  Hereinafter, preferred embodiments of a film-like circuit connection material and a circuit connection structure according to the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments.

  FIG. 1 is a schematic cross-sectional view showing an embodiment of a film-like circuit connecting material according to the present invention. As shown in the figure, the film-like circuit connecting material 1 has an adhesive layer (anisotropic conductive adhesive layer) 61 containing an adhesive component 3 and conductive particles 5. The film-like circuit connecting material (adhesive layer) 1 is used to electrically connect circuit electrodes by interposing between facing circuit electrodes when a circuit connecting structure as described later is manufactured. This film-like circuit connection material 1 is used for, for example, FOG (Film on Glass) connection between a TCP or COF on which a semiconductor for driving an LCD is mounted and an LCD panel, or FOG connection between a TCP or COF and a printed wiring board. Is. The film-like circuit connecting material 1 is also useful for FOP (Film on Plastic) connection.

  The adhesive component 3 contains (a) a thermoplastic resin, (b) a curable substance, (c) a curing agent, and (d) a dye.

  (A) As a thermoplastic resin, polystyrene, polyethylene, polyvinyl butyral, polyvinyl formal, polyimide, polyamide, polyester, polyvinyl chloride, polyphenylene oxide, urea resin, melamine resin, phenol resin, xylene resin, epoxy resin, polyisocyanate resin Phenoxy resin, polyimide resin, polyester urethane resin, etc. are used.

  Among these, a resin having a functional group such as a hydroxyl group is more preferable from the viewpoint of improving adhesiveness. Moreover, what modified | denatured the said thermoplastic resin with the radically polymerizable functional group can also be used. The weight average molecular weight of the thermoplastic resin is preferably 10,000 or more. Further, the weight average molecular weight is preferably less than 1,000,000 because the mixing property tends to decrease when it becomes 1,000,000 or more.

  The weight average molecular weight in the present embodiment is determined by gel permeation chromatography (GPC) analysis under the following conditions and converted using a standard polystyrene calibration curve.

The GPC conditions are as follows.
Equipment used: Hitachi L-6000 type (manufactured by Hitachi, Ltd., trade name)
Detector: L-3300RI (trade name, manufactured by Hitachi, Ltd.)
Column: Gel pack GL-R420 + Gel pack GL-R430 + Gel pack GL-R440 (3 in total) (trade name, manufactured by Hitachi Chemical Co., Ltd.)
Eluent: Tetrahydrofuran Measurement temperature: 40 ° C
Flow rate: 1.75 ml / min

  (A) The content of the thermoplastic resin is preferably 30 parts by mass to 80 parts by mass, and more preferably 35 parts by mass to 70 parts by mass with respect to 100 parts by mass of the adhesive component 3.

  (B) The curable substance can be, for example, (b1) a radically polymerizable substance having a functional group that is polymerized by radicals. Examples of the radical polymerizable substance include acrylates (including corresponding methacrylates, the same applies hereinafter) and maleimide compounds.

  Examples of the acrylate include urethane acrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, trimethylolpropane triacrylate, tetramethylol methane tetraacrylate, 2- Hydroxy-1,3-diaacryloxypropane, 2,2-bis [4- (acryloxymethoxy) phenyl] propane, 2,2-bis [4- (acryloxypolyethoxy) phenyl] propane, dicyclopentenyl acrylate , Tricyclodecanyl acrylate, bis (acryloxyethyl) isocyanurate, ε-caprolactone-modified tris (acryloxyethyl) Isocyanurate, tris (acryloyloxyethyl) isocyanurate.

  As the maleimide compound, those containing at least two maleimide groups in the molecule are preferable. For example, 1-methyl-2,4-bismaleimidebenzene, N, N′-m-phenylenebismaleimide, N, N ′ -P-phenylene bismaleimide, N, N'-m-toluylene bismaleimide, N, N'-4,4-biphenylene bismaleimide, N, N'-4,4- (3,3'-dimethyl-biphenylene ) Bismaleimide, N, N′-4,4- (3,3′-dimethyldiphenylmethane) bismaleimide, N, N′-4,4- (3,3′-diethyldiphenylmethane) bismaleimide, N, N ′ -4,4-diphenylmethane bismaleimide, N, N'-4,4-diphenylpropane bismaleimide, N, N'-4,4-diphenyl ether bisma Imido, N, N′-3,3′-diphenylsulfone bismaleimide, 2,2-bis [4- (4-maleimidophenoxy) phenyl] propane, 2,2-bis [3-s-butyl-4,8 -(4-maleimidophenoxy) phenyl] propane, 1,1-bis [4- (4-maleimidophenoxy) phenyl] decane, 4,4'-cyclohexylidene-bis [1- (4-maleimidophenoxy) -2 -Cyclohexyl] benzene, 2,2-bis [4- (4-maleimidophenoxy) phenyl] hexafluoropropane. These may be used alone or in combination of two or more, and may be used in combination with allyl compounds such as allylphenol, allylphenyl ether, and allyl benzoate.

  (B1) As a radically polymerizable substance, an acrylate is preferable and urethane acrylate or urethane methacrylate is more preferable from the viewpoint of improving adhesiveness. (B1) A radically polymerizable substance can be used alone or in combination of two or more.

  The adhesive component 3 preferably contains at least a radical polymerizable substance having a viscosity at 25 ° C. of 100,000 to 1,000,000 mPa · s, and more preferably contains a radical polymerizable substance of 100,000 to 500,000 mPa · s. The viscosity of the radical polymerizable substance can be measured using a commercially available E-type viscometer.

  (B1) The content of the radical polymerizable substance is preferably 20 to 70 parts by mass, more preferably 30 to 65 parts by mass with respect to 100 parts by mass of the adhesive component.

  (B1) In addition to the above radical polymerizable substance, the radical polymerizable substance is crosslinked with a curing agent (organic peroxide) in order to improve heat resistance and alone exhibits a Tg of 100 ° C. or higher. It is particularly preferred to further contain a substance. As such a radically polymerizable substance, a substance having a dicyclopentenyl group, a tricyclodecanyl group and / or a triazine ring can be used. Among these, radically polymerizable substances having a tricyclodecanyl group or a triazine ring are preferably used. Moreover, you may use suitably polymerization inhibitors, such as hydroquinone and methyl ether hydroquinones, as needed.

  Further, the (b1) radical polymerizable substance preferably further contains a radical polymerizable substance having a phosphate ester structure in addition to the above radical polymerizable substance. The radically polymerizable substance having a phosphoric ester structure is obtained as a reaction product of phosphoric anhydride and 2-hydroxyl (meth) acrylate. Specific examples include 2-methacryloyloxyethyl acid phosphate and 2-acryloyloxyethyl acid phosphate. These can be used individually by 1 type or in combination of 2 or more types.

  The content of the radical polymerizable substance having a phosphate ester structure is 0.1 parts by mass to 10 parts by mass with respect to 100 parts by mass of the adhesive component from the viewpoint of improving the adhesive strength with the surface of an inorganic substance such as a metal. It is preferably 0.5 to 5 parts by mass.

  (B) The curable substance may be (b2) a thermosetting resin. The thermosetting resin is preferably an epoxy resin. The epoxy resin is used alone or in combination of two or more of various epoxy compounds having two or more glycidyl groups in one molecule. Epoxy resins include bisphenol-type epoxy resins derived from epichlorohydrin and bisphenol A, bisphenol F and / or bisphenol AD, and skeletons containing an epoxy novolac resin derived from epichlorohydrin and phenol novolac or cresol novolac, or a naphthalene ring. Naphthalene type epoxy resin having glycidyl amine type epoxy resin, glycidyl ether type epoxy resin, biphenyl type epoxy resin, alicyclic epoxy resin and the like. Epoxy resins can be used alone or in combination of two or more. For the epoxy resin, it is preferable to use a high-purity product in which impurity ions (Na +, Cl-, etc.), hydrolyzable chlorine, etc. are reduced to 300 ppm or less.

  (C) The curing agent is appropriately selected depending on the intended connection temperature, connection time, adherend, etc. (c1) heating such as a peroxide compound (organic peroxide), an azo compound or a photoinitiator And a compound that generates an active radical by at least one treatment of light irradiation.

  From the viewpoint of achieving both high reactivity and excellent pot life, the organic peroxide has a half-life temperature of 40 ° C or higher and a half-life temperature of 1 minute is 180 ° C or lower. preferable. The organic peroxide preferably has a half-life of 10 hours at a temperature of 60 ° C. or more and a half-life of 1 minute at a temperature of 170 ° C. or less. The organic peroxide preferably has a chlorine ion or organic acid content of 5000 ppm or less in order to prevent corrosion of the circuit electrode of the circuit member, and further generates less organic acid after thermal decomposition. Is more preferable.

  The organic peroxide can be selected from, for example, diacyl peroxide, peroxydicarbonate, peroxyester, peroxyketal, dialkyl peroxide, hydroperoxide and the like. Among these, it is preferable to select from peroxyesters, dialkyl peroxides, and hydroperoxides from the viewpoint of suppressing corrosion of connection terminals of circuit members, and from the viewpoint of obtaining high reactivity, it is selected from peroxyesters. More preferably.

  Examples of the diacyl peroxide include isobutyl peroxide, 2,4-dichlorobenzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, and succinic peroxide. , Benzoylperoxytoluene, and benzoyl peroxide.

  Examples of peroxydicarbonate include di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, di-2-ethoxymethoxyperoxydicarbonate, Examples include di (2-ethylhexylperoxy) dicarbonate, dimethoxybutylperoxydicarbonate, and di (3-methyl-3-methoxybutylperoxy) dicarbonate.

  Examples of peroxyesters include cumyl peroxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, 1-cyclohexyl-1-methylethylperoxynoedecanoate, t -Hexylperoxyneodecanoate, t-butylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2,5-dimethyl-2,5-bis ( 2-ethylhexanoylperoxy) hexane, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethyl Hexanonate, t-butylperoxyisobutyrate, 1,1-bis (t-butylperoxy) cyclo Xane, t-hexylperoxyisopropyl monocarbonate, t-butylperoxy-3,5,5-trimethylhexanonate, t-butylperoxylaurate, 2,5-dimethyl-2,5-bis (m- Toluoyl peroxy) hexane, t-butyl peroxyisopropyl monocarbonate, t-butyl peroxy-2-ethylhexyl monocarbonate, t-hexyl peroxybenzoate, t-butyl peroxyacetate.

  Examples of the peroxyketal include 1,1-bis (t-hexylperoxy) -3,5,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) cyclohexane, 1,1-bis ( t-butylperoxy) -3,5,5-trimethylcyclohexane, 1,1- (t-butylperoxy) cyclododecane, 2,2-bis (t-butylperoxy) decane.

  Examples of the dialkyl peroxide include α, α′-bis (t-butylperoxy) diisopropylbenzene, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, t -Butyl cumyl peroxide is mentioned.

  Examples of the hydroperoxide include diisopropylbenzene hydroperoxide and cumene hydroperoxide.

  Examples of the azo compound include 2,2′-azobis-2,4-dimethylvaleronitrile, 1,1′-azobis (1-acetoxy-1-phenylethane), and 2,2′-azobisisobutyronitrile. 2,2′-azobis (2-methylbutyronitrile), dimethyl-2,2′-azobisisobutyronitrile, 4,4′-azobis (4-cyanovaleric acid) and 1,1′-azobis ( 1-cyclohexanecarbonitrile).

  Photoinitiators include, for example, benzoin ethers such as benzoin ethyl ether and isopropyl benzoin ether, benzyl ketals such as benzyl and hydroxycyclohexyl phenyl ketone, ketones and derivatives thereof such as benzophenone and acetophenone, thioxanthones, and bisimidazoles Are preferably used.

  When a photoinitiator is used, an optimal photoinitiator is selected according to the wavelength of the light source used, desired curing characteristics, and the like. Moreover, you may use together sensitizers, such as amines, a sulfur compound, and a phosphorus compound, with a photoinitiator in arbitrary ratios as needed.

  Sensitizers include aliphatic amines, aromatic amines, cyclic amines such as piperidine having a nitrogen-containing cyclic structure, o-tolylthiourea, sodium diethyldithiophosphate, soluble sulfinic acid salts, N, N′-dimethyl -P-aminobenzonitrile, N, N'-diethyl-p-aminobenzonitrile, N, N'-di (β-cyanoethyl) -p-aminobenzonitrile, N, N'-di (β-chloroethyl)- P-aminobenzonitrile, tri-n-butylphosphine and the like are preferable. As sensitizers, propiophenone, acetophenone, xanthone, 4-methylacetophenone, benzophenone, fluorene, triphenylene, biphenyl, thioxanthone, anthraquinone, 4,4'-bis (dimethylamino) benzophenone, 4,4'- Bis (diethylamino) benzophenone, phenanthrene, naphthalene, 4-phenylacetophenone, 4-phenylbenzophenone, 1-iodonaphthalene, 2-iodonaphthalene, acenaphthene, 2-naphthonitrile, 1-naphthonitrile, chrysene, benzyl, fluoranthene, pyrene, Non-pigment sensitizers such as 1,2-benzoanthracene, acridine, anthracene, perylene, tetracene, 2-methoxynaphthalene, thionine, methylene blue, lumiflavin, ribo Rabin, lumichrome, coumarin, psoralen, 8-methoxypsoralen, 6-methylcoumarin, 5-methoxypsoralen, 5-hydroxypsoralen, coumarylpyrone, acridine orange, acriflavine, proflavine, fluorescein, eosin Y, eosin B, erythrosine Examples include dye-based sensitizers such as Bengal.

  These free radical generators can be used singly or in combination of two or more, and may be used by mixing a decomposition accelerator, an inhibitor and the like. Moreover, it is preferable that it is 0.05 weight%-10 mass% with respect to the whole adhesive agent component, and, as for content of a free radical generator, it is more preferable that it is 0.1 weight%-5 mass%.

  The (c) curing agent is preferably a (c2) latent curing agent from the viewpoint of obtaining a longer pot life. (B) When the polymerizable substance is (b2) an epoxy resin as a thermosetting resin, the latent curing agent includes imidazole, hydrazide, boron trifluoride-amine complex, sulfonium salt, amine imide, polyamine salt And dicyandiamide. These can be used individually by 1 type or in mixture of 2 or more types. The latent curing agent may be mixed with a decomposition accelerator, an inhibitor and the like. The latent curing agent is preferably microencapsulated by coating with a polyurethane-based or polyester-based polymeric substance or the like because the pot life is extended.

  (D) The dye preferably contains at least one dye selected from a black dye, a green dye, and a blue dye. In this case, even the most widely used sensor using a red laser can be sufficiently recognized, and in particular, the recognizability is higher than when a blue color which is a complementary color of red is contained.

  In a hue circle composed of 12 different colors, a dye having a complementary color relationship with the color used in the laser or a dye having a complementary color relationship (a color adjacent to each color in the hue circle) Is preferable, and it is more preferable to use a dye having a complementary color. Thus, for example, when a red laser is used, a blue dye and / or a green dye is preferable, when a green / blue laser is used, a red dye is preferable, and when a red / yellow laser is used, a blue dye is preferable.

  The dye is preferably soluble in a low boiling point solvent such as toluene, methyl ethyl ketone, and ethyl acetate from the viewpoint of suppressing aggregation during heating and pressurization. The boiling point of the low boiling point solvent is preferably 50 to 140 ° C, more preferably 60 to 130 ° C. From the viewpoint of storage stability of the circuit connection material and connection reliability of the circuit connection structure, it is preferable to use a non-hydrophilic dye instead of a hydrophilic dye.

  It is preferable that content of dye is 0.05-1.0 mass part with respect to 100 mass parts of adhesive components, 0.05-0.5 mass part is more preferable, 0.05-0.3 Part by mass is more preferable. In this case, the visibility of the film-like circuit connecting material itself can be particularly improved, and after the film-like circuit connecting material is attached to the adherend, the alignment mark placed on the adherend is more easily recognized. be able to.

  Next, the conductive particles 5 will be described. FIG. 2 is a schematic cross-sectional view illustrating the conductive particles 5.

  For example, as shown in FIG. 2A, the conductive particle 5 includes a core body 21 and a metal layer 22 that covers the surface of the core body 21. In this conductive particle 5, the core body 21 has a core portion 21a and a protrusion 21b formed on the surface of the core portion 21a. The metal layer 22 is formed so as to cover the entire core body 21 including the core portion 21a and the protruding portion 21b. As a result, the protrusion 14 is formed on the surface of the conductive particle 5 by the metal layer 22 that covers the protrusion 21 b.

  The core 21 is preferably made of an organic polymer compound such as plastic. By using a plastic core, the cost of the core 21 can be reduced compared to a core made of metal. Moreover, the elastic deformation range with respect to the coefficient of thermal expansion and the dimensional change during pressure bonding can be secured, which is particularly suitable for circuit connection applications.

  Examples of the organic polymer compound constituting the core portion 21a of the core body 21 include acrylic resin, styrene resin, benzoguanamine resin, silicone resin, polybutadiene resin, or a copolymer thereof. May be. The organic polymer compound constituting the protruding portion 21b of the core body 21 may be the same as or different from the organic polymer compound constituting the core portion 21a.

  The average particle size of the core 21a of the core 21 is preferably 2.0 μm to 3.5 μm, more preferably 2.0 μm to 3.25 μm, and 2.5 μm to 3.0 μm. Is more preferable. When the average particle size is less than 1 μm, secondary aggregation of the particles occurs, and the insulation with an adjacent circuit tends to be insufficient. On the other hand, if the average particle size exceeds 5 μm, the insulation from adjacent circuits tends to be insufficient due to the size. Therefore, the insulating property of a circuit can be suitably ensured by setting the average particle diameter of the core portion 21a within the above range.

  The core 21 can be formed by adsorbing a plurality of protrusions 21b having a smaller diameter than the core 21a on the surface of the core 21a. As a method for adsorbing the protrusion 21b on the surface of the core 21a, for example, the core 21a and the protrusion 21b or both particles may be diluted with various coupling agents such as silane, aluminum, titanium, and an adhesive. After surface treatment, the method of mixing and adhering both is mentioned. In addition, it is preferable that the average particle diameter of the protrusion part 21b is 50 micrometers-500 nm.

  The metal layer 22 is formed to include a metal having a Vickers hardness of 300 Hv or higher, such as Ni, Pd, and Rh. Examples of Ni include at least one selected from the group consisting of pure Ni, Ni alloy, and Ni oxide. Among these, pure Ni and pure Pd are preferable. Examples of the Ni alloy include Ni-B, Ni-W, Ni-B, Ni-W-Co, Ni-Fe, and Ni-Cr. Examples of the Ni oxide include NiO. The metal layer 22 may be composed of a single layer or may be composed of a plurality of layers. When the metal layer 22 is composed of a plurality of layers, the outermost layer is preferably metal plating including at least one selected from the group consisting of Ni, Ni alloys, and Ni oxides. The Vickers hardness can be measured using, for example, “Maicroharadness Tester MHT-4 (trade name)” manufactured by Japan High-Tech, under the conditions of a load load of 20 kgf, a load speed of 20 kgf / second, and a holding time of 5 seconds. .

  The metal layer 22 can be formed by, for example, plating the above metal on the core body 21 using an electroless plating method. The electroless plating method is roughly divided into a batch method and a continuous dropping method, and any method may be used.

  The thickness of the metal layer 22 is preferably 50 μm to 170 nm, and more preferably 50 nm to 150 nm. By setting the thickness of the metal layer 22 in such a range, the connection resistance between the circuit electrodes can be reduced. If the thickness of the metal layer 22 is less than 50 nm, plating defects tend to occur, and if it exceeds 170 nm, condensation occurs between the conductive particles and a short circuit tends to occur between adjacent circuit electrodes. Therefore, by making the thickness of the metal layer 22 in the above range, the circuit electrodes can be suitably connected.

  Note that the core 21 may be partially exposed in the conductive particles 5. In this case, from the viewpoint of connection reliability, the coverage of the metal layer 22 with respect to the surface area of the core 21 is preferably 70% or more, more preferably 80% or more, and further preferably 90% or more. preferable.

  The height of the protrusion 14 of the conductive particle 5 is preferably 50 nm to 500 nm, and more preferably 75 nm to 300 nm. If the height of the protrusion 14 is less than 50 nm, the connection resistance tends to increase after the high-temperature and high-humidity treatment, and if it exceeds 500 nm, the contact area between the conductive particles and the circuit electrode is reduced, so that the connection resistance is increased. Tend. Therefore, the connection resistance can be suppressed by setting the height of the protrusion 14 within the above range.

  The distance between the adjacent protrusions 14 and 14 is preferably 1000 nm or less, and more preferably 500 nm or less. Moreover, the distance between the adjacent protrusions 14 and 14 is such that the cured body 11 (described later) of the adhesive component 3 does not enter between the conductive particles 5 and the circuit electrodes, and the conductive particles 5 and the circuit electrodes are sufficiently in contact with each other. Therefore, it is preferable that the thickness is at least 50 nm. In addition, the height of the protrusion part 14 and the distance between the adjacent protrusion parts 14 can be measured with an electron microscope.

  As shown in FIG. 2B, the conductive particles 5 may be configured only with the core 21a without providing the protrusions 21b. Such conductive particles 5 can be obtained by metal-plating the surface of the core portion 21a and forming the metal layer 22 having the protrusions 14 on the surface of the core portion 21a.

  Such a protrusion 14 can be formed by partially changing the thickness of the metal layer 22 by changing the plating conditions during metal plating. In this case, for example, a plating solution having a higher concentration than the plating solution used first can be added during the plating reaction to make the concentration of the plating solution non-uniform.

  Further, as shown in FIG. 2C, the conductive particles 5 may have a simple spherical shape without providing the protrusions 14.

  The conductive particles 5 as described above may be those in which insulating particles such as non-conductive glass, ceramic, and plastic are covered with a metal layer 22 containing Ni or the like. When the metal layer 22 includes Ni and the core 21 is plastic, or when the conductive particles 5 are hot-melt metal particles, the metal particles 22 are deformable by heating and pressurization, and the conductive particles 5 and the circuit electrodes are connected at the time of connection. The contact area is increased and the connection reliability is improved, which is preferable.

  The content of the conductive particles 5 is preferably 0.1 to 20 parts by volume with respect to 100 parts by volume of the adhesive component 3 in the anisotropic conductive layer, and is appropriately adjusted depending on the application. In addition, the content of the conductive particles 5 is 0.1 volume parts to 10 volumes with respect to 100 volume parts of the adhesive component 3 in the anisotropic conductive layer from the viewpoint of more sufficiently suppressing short circuit between adjacent circuits. More preferably, it is a part.

Further, from the viewpoint of the more reliable conduction between the circuit electrodes, 10% compressive elasticity modulus of the conductive particles 5 (K value) ^is preferably ^{100kgf / mm 2 ~1000kgf / mm 2} . The 10% compression modulus (K value) refers to the modulus of elasticity when the conductive particles 5 are 10% compressed and deformed, and can be measured by, for example, an H-100 micro hardness tester manufactured by Fisher Instruments Co., Ltd.

  The average particle diameter of the conductive particles 5 is preferably 2.0 μm to 3.5 μm from the viewpoint of further easily suppressing a short circuit between adjacent circuit electrodes by making it lower than the height of the circuit electrodes to be connected. The thickness is more preferably 0.0 μm to 3.25 μm, and further preferably 2.5 μm to 3.0 μm. Here, the “average particle diameter” of the conductive particles 5 means a particle diameter calculated without including the height of the protrusions 14.

  The average particle diameter of the conductive particles 5 can be measured as follows. First, 50 particles are arbitrarily selected from a particle image of conductive particles magnified 3000 times with a differential scanning electron microscope (SEM: for example, S800 manufactured by HITACHI). Next, the maximum diameter and the minimum diameter are measured for each of the selected plurality of particles using the enlarged particle image. The square root of the product of the maximum diameter and the minimum diameter of each particle is defined as the particle diameter of the particle. The particle diameter of each of 50 arbitrarily selected conductive particles is measured as described above, and the value obtained by dividing the sum of the particle diameters by the measured number of particles is taken as the average particle diameter.

When viewed from the thickness direction of the film-like circuit connecting material 1 (direction perpendicular to the main surface), the number of conductive particles 5 present per 1 mm ² is preferably 2000 to 15000, 3000 to 13000. More preferably. In that case, it is possible to obtain a contact area of the conductive particles sufficient to obtain a better connection resistance and to sufficiently prevent a short circuit between the circuits.

  Furthermore, the film-like circuit connecting material 1 of the present embodiment includes rubber fine particles, fillers, softeners, accelerators, anti-aging agents, colorants, flame retardants, thixotropic agents, coupling agents, phenol resins, melamines. You may contain resin, isocyanates, etc.

  As the rubber fine particles, the average particle size of the particles is not more than twice the average particle size of the conductive particles 5 to be blended, and the storage elastic modulus at room temperature (25 ° C.) is the room temperature of the conductive particles 5 and the adhesive component 3. Those having a storage elastic modulus of not more than ½ are preferred. In particular, when the material of the rubber fine particles is silicone, acrylic emulsion, SBR, NBR, or polybutadiene rubber, it is preferable to use one kind alone or a mixture of two or more kinds. These three-dimensionally crosslinked rubber fine particles have excellent solvent resistance and are easily dispersed in the adhesive component 3.

  The filler contributes to improvement in connection reliability and the like. The maximum diameter of the filler is preferably less than the average particle diameter of the conductive particles 5. The content of the filler is preferably in the range of 5% by volume to 60% by volume with respect to the entire circuit connecting adhesive film 1. When the content exceeds 60% by volume, the effect of improving reliability tends to be saturated.

  As the coupling agent, a compound containing one or more groups selected from the group consisting of a vinyl group, an acrylic group, an amino group, an epoxy group, and an isocyanate group is preferable from the viewpoint of improving adhesiveness.

  The film-like circuit connecting material 1 is one in which the adhesive melts and flows at the time of connection, connects the circuit electrodes facing each other, and then cures to maintain the connection. The fluidity of the adhesive is an important factor. When the film-like circuit connecting material 1 having a thickness of 35 μm and 5 mm × 5 mm is sandwiched between a glass plate having a thickness of 0.7 mm and 15 mm × 15 mm, and heating and pressurization are performed at 170 ° C., 2 MPa, and 10 seconds, The value of the fluidity (B) / (A) expressed by using the area (A) and the area (B) after heating and pressing is preferably 1.3 to 3.0, and 1.5 More preferably, it is -2.5. When (B) / (A) is less than 1.3, the fluidity is poor and there is a tendency that good connection cannot be obtained. When it exceeds 3.0, bubbles tend to be generated and the reliability tends to be poor. Moreover, it is preferable that the elasticity modulus in 40 degreeC after hardening of the film-form circuit connection material 1 is 100 MPa-3000 MPa, and it is more preferable that it is 500 MPa-2000 MPa.

  Then, the circuit connection structure 100 formed using the film-form circuit connection material 1 is demonstrated. FIG. 3 is a schematic cross-sectional view showing an embodiment of a circuit connection structure according to the present invention. As shown in the figure, the circuit connection structure 100 includes a circuit member (first circuit member) 30 and a circuit member (second circuit member) 40 facing each other, and the circuit member 30 and the circuit member 40. And a circuit connecting member 10 for connecting them.

  The circuit member 30 includes a circuit board 31 and a circuit electrode (first circuit electrode) 32 formed on the main surface 31 a of the circuit board 31. The circuit member 40 includes a circuit board 41 and a circuit electrode (second circuit electrode) 42 formed on the main surface 41 a of the circuit board 41.

  The material of the circuit boards 31 and 41 is not particularly limited, but is usually an organic insulating material, glass or silicon. Examples of the material of the circuit electrodes 32 and 42 include Au, Ag, Sn, and Pt group metals, indium-tin oxide (ITO), indium-zinc oxide (IZO), Al, and Cr. At least one of the circuit electrodes 32 and 42 preferably contains at least one of indium-tin oxide (ITO) and indium-zinc oxide (IZO) from the viewpoint of significantly improving electrical connection. Further, the circuit electrodes 32 and 42 may be entirely made of the above material, or only the outermost layer may be made of the above material.

  At least one of the circuit members 30 and 40, preferably the circuit pitch of the flexible substrate is 200 μm or less. Further, the lower limit of the circuit pitch is not particularly limited, but can be about 20 μm, for example. The surfaces of the circuit electrodes 32 and 42 are preferably flat. Here, “the surface of the circuit electrode is flat” means that the unevenness of the surface of the circuit electrode is 20 nm or less.

  When the conductive particles 5 having protrusions are used, when the thickness of the circuit electrodes 32 and 42 is less than 50 nm, the conductive particles are pressed when the circuit connecting adhesive film 1 is pressed between the circuit members 30 and 40. 5 may penetrate the circuit electrodes 32 and 42 and directly contact the circuit boards 31 and 41. Therefore, by setting the thickness of the circuit electrodes 32 and 42 to 50 nm or more, the contact area between the circuit electrodes 32 and 42 and the conductive particles 5 can be increased, and the connection resistance can be further reduced. In addition, the thickness of the circuit electrodes 32 and 42 is preferably 1000 nm or less, and more preferably 500 nm or less, from the viewpoint of manufacturing cost.

  In the circuit member 30, an insulating layer may be further provided between the circuit electrode 32 and the circuit board 31. In the circuit member 40, an insulating layer is further provided between the circuit electrode 42 and the circuit board 41. May be. The material of the insulating layer is not particularly limited as long as it is made of an insulating material, but is usually an organic insulating material, silicon dioxide or silicon nitride.

  Specific examples of the first circuit member 30 and the second circuit member 40 include chip components such as a semiconductor chip, a resistor chip, and a capacitor chip, and a substrate such as a printed circuit board. These circuit members 30 and 40 are usually provided with a large number of circuit electrodes (connection terminals) 32 and 42 (in some cases, the number may be one).

  The circuit connection member 10 is obtained by curing the above-described film-like circuit connection material 1 and includes a cured body 11 obtained by curing the adhesive component 3 and the conductive particles 5.

  In the circuit connection structure 100, the facing circuit electrode 32 and the circuit electrode 42 are electrically connected through the conductive particles 5. That is, the conductive particles 5 are electrically connected by directly contacting both the circuit electrodes 32 and 42. When the conductive particle 5 has a plurality of protrusions, it is preferable that a part of the conductive particle 5 bites into the circuit electrode 32 or the circuit electrode 42. In this case, the contact area between the protrusions of the conductive particles and the circuit electrodes 32 and 42 can be further increased, and the connection resistance can be further reduced.

  FIG. 4 is a process cross-sectional view schematically showing the method for manufacturing the circuit connection structure. FIG. 4A shows a state before the circuit members are connected to each other, FIG. 4B shows a state when the circuit members are connected to each other, and FIG. The circuit connection structure after connecting is shown.

  First, as shown in FIG. 4A, an LCD panel 73 having a circuit electrode 72 and a liquid crystal display 74 on the main surface is prepared. Next, a film-like circuit connecting material (adhesive layer) 61 equivalent to the circuit connecting adhesive film 1 is adhered and placed on the circuit electrode 72. Then, the circuit board 75 provided with the circuit electrode 76 such as COF is aligned so that the circuit electrode 72 and the circuit electrode 76 face each other through the film-like circuit connecting material 61. The circuit electrode 72 and the circuit electrode 76 have, for example, a structure in which a plurality of electrodes are arranged.

  Next, as shown in FIG. 4B, the circuit electrode 72 and the circuit electrode 76 are opposed to each other through the film-like circuit connecting material 61 while aligning the LCD panel 73 and the circuit board 75. Then, the circuit board 75 is placed on the film-like circuit connecting material 61. Thereby, the circuit electrode 72 and the circuit electrode 76 are connected by the conductive particles 5 in the film-like circuit connecting material 61.

  Next, the circuit board 75 is pressurized from the surface opposite to the surface on which the circuit electrodes 76 are arranged (in the direction of arrow A in FIG. 4B), and the film-like circuit connecting material 61 is heated. Thereby, the film-form circuit connection material 61 hardens | cures and the circuit connection member 60 is obtained. 4C, the circuit connection structure 70 in which the LCD panel 73 and the circuit board 75 are firmly connected via the circuit connection member 60 is obtained. In addition, the method of a hardening process can employ | adopt one or both of a heating and light irradiation according to the adhesive agent component to be used.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

Example 1
While stirring 400 parts by mass of polycaprolactone diol having a weight average molecular weight of 800, 131 parts by mass of 2-hydroxypropyl acrylate, 0.5 parts by mass of dibutyltin dilaurate as a catalyst, and 1.0 part by mass of hydroquinone monomethyl ether as a polymerization inhibitor, 50 Heat to ℃ and mix. Next, 222 parts by mass of isophorone diisocyanate was dropped, and the temperature was raised to 80 ° C. while stirring to carry out a urethanization reaction. After confirming that the reaction rate of the isocyanate group was 99% or more, the reaction temperature was lowered to obtain urethane acrylate.

  Further, terephthalic acid was used as the dicarboxylic acid, propylene glycol was used as the diol, and 4,4′-diphenylmethane diisocyanate was used as the isocyanate, and the molar ratio of terephthalic acid / propylene glycol / 4,4′-diphenylmethane diisocyanate was 1.0 / 1.3 / A 0.25 polyester urethane resin A was prepared.

  Next, the said polyester urethane resin was melt | dissolved in methyl ethyl ketone so that it might become 20 mass%. Using a methyl ethyl ketone solution of the above-mentioned polyester urethane resin, it was applied to a PET film having a thickness of 80 [mu] m on one surface (silicone treatment) using a coating apparatus. Furthermore, a film having a thickness of 35 μm was produced by hot air drying at 70 ° C. for 10 minutes. The temperature dependence of the elastic modulus was measured at a tensile load of 5 g and a frequency of 10 Hz using a wide-range dynamic viscoelasticity measuring device (trade name: RSAII, manufactured by Rheometric Scientific). The glass transition temperature of polyester urethane resin A obtained from the measurement results was 105 ° C.

  25 parts by mass of the urethane acrylate as a radical polymerizable substance, 20 parts by mass of isocyanurate type acrylate (product name: M-325, manufactured by Toagosei Co., Ltd.), 2-methacryloyloxyethyl acid phosphate (product name: P-2M) , Manufactured by Kyoeisha Chemical Co., Ltd.) 1 part by mass, and 4 parts by mass of benzoyl peroxide (product name: Nyper BMT-K40, manufactured by NOF Corporation) as a free radical generator, the polyester urethane resin as a film-forming polymer The mixture was mixed with 55 parts by mass of a 20% methyl ethyl ketone solution of A, and 0.5 parts by mass of a black dye (product name: NUBIAN BLACK, manufactured by Orient Kogyo Co., Ltd.) was dispersed and stirred to obtain a binder resin.

Furthermore, conductive particles (average particle diameter: 3 μm, hereinafter sometimes referred to as “Ni-coated particles”) covered with an outermost layer containing Ni whose core is polystyrene and having protrusions on the surface of the outermost layer. 2% by volume (number of particles: 7000 particles / mm ² ) was mixed and dispersed with respect to the binder resin. Then, the mixed solution was applied using a coating apparatus to the surface of the PET film having a thickness of 50 μm that had been subjected to surface treatment (silicone treatment) on one side, and dried by hot air at 70 ° C. for 10 minutes. An adhesive layer (width 15 cm, length 70 m) having a thickness of 18 μm was formed as the anisotropic conductive adhesive layer A. The obtained anisotropic conductive adhesive layer A was cut to a width of 1.5 mm, and wound with 50 m with the plastic reel adhesive film face inside, to obtain a tape-like film-like circuit connection material.

(Examples 2 to 16)
A film-like circuit connecting material was obtained in the same manner as in Example 1 except that the average particle diameter of conductive particles, the number of conductive particles, the type of dye, the amount of dye, and the thickness of the film-like circuit connecting material were changed as shown in FIG. Produced.

(Examples 17 and 18)
25 parts by mass of the urethane acrylate as a radical polymerizable substance, 20 parts by mass of isocyanurate type acrylate (product name: M-325, manufactured by Toagosei Co., Ltd.), 2-methacryloyloxyethyl acid phosphate (product name: P-2M) ) 1 part by mass and 4 parts by mass of benzoyl peroxide (product name: Nyper BMT-K40) as a free radical generator are added to 55 parts by mass of a 20% methyl ethyl ketone solution of the polyester urethane resin A as a film-forming polymer. After mixing, 0.5 part by mass of a black dye (product name: NUBIAN BLACK, manufactured by Orient Kogyo Co., Ltd.) was dispersed and stirred to obtain a binder resin.

  Furthermore, 4% by volume (6000 particles / mm 2) of conductive particles (average particle diameter: 3 μm) covered with an outermost layer containing Ni having polystyrene as a core and having protrusions on the surface of the outermost layer with respect to the binder resin. Formulated and dispersed. Then, the mixed solution was applied using a coating apparatus to the surface of the PET film having a thickness of 50 μm that had been subjected to surface treatment (silicone treatment) on one side, and dried by hot air at 70 ° C. for 10 minutes. An adhesive layer having a thickness of 3 μm (width: 15 cm, length: 70 m) was formed as the anisotropic conductive adhesive layer A.

  25 parts by mass of the urethane acrylate as a radical polymerizable substance, 20 parts by mass of an isocyanurate type acrylate (product name: M-325), 1 part by mass of 2-methacryloyloxyethyl acid phosphate (product name: P-2M), And 4 parts by mass of benzoyl peroxide (product name: Nyper BMT-K40) as a free radical generator are mixed with 55 parts by mass of a 20% methyl ethyl ketone solution of the above-described polyester urethane resin A as a film-forming polymer and stirred. A binder resin was used. Next, the binder resin was applied using a coating apparatus to the surface of the PET film having a thickness of 50 μm that was surface-treated on one side (silicone treatment), and dried with hot air at 70 ° C. for 10 minutes. An adhesive layer B (width 15 cm, length 70 m) having a thickness of 10 μm was obtained.

  After overlaying anisotropic conductive adhesive layer A and adhesive B and laminating them using a laminator (Dupont RISTON, model; HRL, roll pressure is spring load only, roll temperature 40 ° C., speed 50 cm / min) The anisotropic conductive adhesive layer A side PET was peeled off to obtain a 14 μm thick adhesive layer (width 15 cm, length 60 m) as an anisotropic conductive adhesive. The obtained anisotropic conductive adhesive was cut to a width of 1.5 mm, and wound on a plastic reel with an adhesive film surface inside by 50 m to obtain a tape-like film-like circuit connecting material.

(Reference Example 1, Comparative Examples 1 to 11)
Example 1 except that the average particle size of the conductive particles, the number of particles of the conductive particles, the thickness of the film-like circuit connecting material, the dye amount, and the layer configuration of the film-like circuit connecting material were changed as shown in FIG. Thus, a film-like circuit connecting material was produced.

(Circuit connection)
The adhesive layer of the film-like circuit connecting material (width 1.5 mm, length 3 cm) obtained in the examples and comparative examples was heated and pressed at 70 ° C. and 1 MPa for 1 second to provide a 0.7 mm thick Cr / indium. -Transferred onto a zinc oxide (IZO) coated glass substrate and peeled off the PET film. Next, a flexible circuit board (FPC) having 500 tin-plated copper circuits with a pitch of 40 μm and a thickness of 8 μm was placed on the transferred adhesive layer, and temporarily fixed by pressing at 24 ° C. and 0.5 MPa for 1 second. (However, for a sample having a conductive particle diameter of 10 μm, a flexible circuit board having 100 gold-plated copper circuits with a pitch of 100 μm and a thickness of 18 μm was used as the FPC.) The FPC was temporarily fixed by a circuit connection film. A glass substrate is installed in the main pressure bonding apparatus, and a 150 μm thick Teflon (registered trademark) sheet is used as a cushioning material. , Got the connection.

(Measurement of connection resistance)
About the said connection body, the resistance value in each electrode was measured with the digital multimeter (device name: TR6845, product made from an Advantest company) by 4 terminal method, and the average value of 10 electrodes was calculated | required.

(Measurement of the number of conductive particles)
Using a BH3-MJL liquid crystal panel inspection microscope manufactured by Olympus Corporation, the film-like circuit connecting material was observed from the thickness direction, and the number of conductive particles per 1 mm ² was measured by image analysis.

(Visibility of film-like circuit connection material)
An adhesive layer made of a film-like circuit connection material (width 1.5 mm, length 3 cm) is heated and pressurized at 70 ° C. and 1 MPa for 1 second, transferred onto a 0.7 mm thick slide glass substrate, and the PET film is peeled off. A sample was prepared. After placing A4 size OA paper on a white work table and placing the sample on it, using a sensor equipped with Hybrid Fiber Sensor FS-V11 as a red LED light source on Switching Power Supply MS2-H50 manufactured by KEYENCE Irradiate red light from the film-like circuit connection material side to the part (A) where only the film-like circuit connection material is pasted and the part (A) where only the glass slide is not pasted. The intensity of reflected light was measured. The case where the difference in the intensity of the reflected light between the part (A) and the part (B) was sufficiently large was determined to be OK, and the case where the difference was small was determined to be NG.

(Verification of visibility)
An adhesive layer of a film-like circuit connection material (width 1.2 mm, length 4 cm) is heated and pressed at 70 ° C. and 1 MPa for 1 second using a film-type circuit connection material pasting apparatus manufactured by Panasonic, thickness 0.7 mm The film was transferred onto the TFT glass substrate and the PET film was peeled off. And using the laser sensor installed in the apparatus, it was confirmed from the film side whether the film-form circuit connection material was appropriately affixed on the glass substrate.

(Visibility of alignment mark)
An adhesive layer of film-like circuit connection material (width 1.5 mm, length 3 cm) is heated and pressed at 70 ° C. and 1 MPa for 1 second to mount alignment marks. Tin-plated copper with a pitch of 40 μm and a thickness of 8 μm It was transferred onto a flexible circuit board (FPC) having 500 circuits, and the PET film was peeled off. The said sample was observed from the thickness direction of the film-form circuit connection material using the Olympus BH3-MJL liquid crystal panel inspection microscope, and it was confirmed whether the alignment mark part was visible. The case where the alignment mark was visible was determined to be OK, and the case where the alignment mark was not visible was determined to be NG.

  FIG. 7 is a diagram illustrating the evaluation results of the film for circuit connection according to Examples and Comparative Examples. As shown in the figure, in the embodiment, the connection resistance is suppressed to 0.4Ω to 0.9Ω. Moreover, in an Example, after sticking to a to-be-adhered material, it becomes easy to visually recognize the position of an adhesive agent from the film side. On the other hand, in the comparative example, the connection resistance is 0.7Ω to 3.5Ω, which is higher than the example. Further, in the comparative example, it is difficult to visually recognize the position of the adhesive from the film side after being attached to the adherend. In Comparative Example 8, although the visibility of the circuit connection material was improved as compared with other Comparative Examples, it was not yet sufficient as compared with the Examples. In addition, it can be seen from Reference Example 1 that when conductive particles having an average particle diameter larger than 3.5 μm are used, the problem of visibility does not occur.

  DESCRIPTION OF SYMBOLS 1,61 ... Film-like circuit connection material (adhesive layer), 3 ... Adhesive component, 5 ... Conductive particle, 14 ... Protrusion part, 21 ... Core, 22 ... Metal layer (outermost layer), 30, 40 ... Circuit Member, 32, 42, 72, 76 ... circuit electrode, 70, 100 ... circuit connection structure.

Claims (3)

Having an adhesive layer that is electrically connected between the circuit electrodes interposed between opposing circuit electrodes;
The adhesive layer is
An adhesive component containing (a) a thermoplastic resin, (b) a curable material, (c) a curing agent, and (d) a dye;
A metal core covering the plastic core and the plastic core, the outermost layer of the metal layer being a metal plating containing at least one selected from the group consisting of Ni, Ni alloy and Ni oxide, Conductive particles having a particle size of 2.0 to 3.5 μm;
A film-like circuit connecting material comprising: The number of the conductive particles is from 2,000 to 15,000 pieces / mm ² when viewed from the thickness direction of the adhesive layer, the film-like circuit connecting material according to claim 1.   The adhesive layer of the film-like circuit connecting material according to claim 1 or 2 is interposed between the first circuit member having the first circuit electrode and the second circuit member having the second circuit electrode. A circuit connection structure obtained by electrically connecting the first circuit electrode and the second circuit electrode by heating and applying pressure thereto.

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