JP5737278B2 - Circuit connection material, connection body, and method of manufacturing connection body - Google Patents

Description

  The present invention relates to a circuit connection material, a connection body, and a method for manufacturing the connection body.

  In recent years, electronic components have been reduced in size, thickness and performance, and economical high-density mounting technology has been actively developed. It is difficult to cope with the connection between the electronic component and the fine circuit electrode by the conventional solder and rubber connector. Therefore, an anisotropic conductive adhesive excellent in resolution and a connection method using the film are frequently used. For example, when connecting a liquid crystal display (Liquid Crystal Display) glass and a circuit member such as TAB (Tape Automated Bonding) and FPC (Flexible Print Circuit), an anisotropic conductive adhesive film containing conductive particles. Electrons having fine electrodes by electrically connecting the electrodes of both substrates while maintaining the insulation between adjacent electrodes on the same substrate by sandwiching between the electrodes facing each other and heating and pressing The component and the circuit member are bonded and fixed.

  In order to reduce the weight and thickness of modules, studies are underway to use flexible substrates such as plastic substrates instead of conventional glass substrates as substrates for display modules such as liquid crystal display devices and electronic paper. .

Japanese Patent Laid-Open No. 08-148213 Japanese Patent Application Laid-Open No. 08-124613 Japanese Patent Laid-Open No. 11-50032

  A flexible wiring board generally has a flexible substrate containing a thermoplastic resin and an electrode formed on the flexible substrate. The electrodes of the flexible wiring board are mainly thin films such as metals.

  In order to connect a high-definition circuit, an anisotropic conductive adhesive containing conductive particles is often used as a circuit connection material. However, when a conventional circuit connection material is used, there is a problem that the electrodes on the flexible substrate are easily broken or cracked by heating and pressurization for circuit connection.

  Therefore, the main object of the present invention is to sufficiently prevent the electrodes on the flexible substrate from being damaged when the circuit member having the flexible substrate is connected by a circuit connecting material containing conductive particles.

  The present invention relates to a circuit connecting material containing an insulating adhesive and conductive particles dispersed in the insulating adhesive. The circuit connection material according to the present invention includes a first circuit member having a first substrate and a first connection terminal provided on the first substrate, a second substrate, and the second substrate. It is used to electrically connect and bond the second circuit member having the provided second connection terminal. The first substrate and / or the second substrate is a flexible substrate containing a thermoplastic resin. The conductive particles have plastic particles and a metal layer (metal coating) that covers the plastic particles. The compression hardness K value when the conductive particles are compressed and displaced by 20% of the diameter is, for example, 0.20 to 3.2 GPa.

  According to the circuit connection material according to the present invention, it is possible to obtain a connection body in which circuit members are electrically connected while preventing damage to electrodes on the flexible substrate.

  The first substrate is an IC chip or a flexible substrate, and the second substrate is a flexible substrate containing at least one thermoplastic resin selected from the group consisting of polyimide, polyethylene terephthalate, polycarbonate and polyethylene naphthalate. Good.

  The compression hardness K value when the conductive particles are compressed and displaced by 40% of the diameter thereof may be 0.29 to 3.4 GPa.

  The compression recovery rate of the conductive particles may be 1 to 90%.

  The conductive particles may further have an insulating resin layer provided outside the metal layer.

  The storage elastic modulus E ′ at a frequency of 10 Hz of the circuit connecting material at 40 ° C. after being heated at 170 ° C. or lower for 10 seconds may be 0.5 to 2.5 GPa.

  In another aspect, the present invention is a first circuit member having a first substrate and a first connection terminal provided on the first substrate, and is disposed to face the first circuit member. A second circuit member having a second substrate and a second connection terminal provided on the second substrate; and a first circuit provided between the first circuit member and the second circuit member. The present invention relates to a connection body including an adhesive layer that electrically connects and bonds a member and a second circuit member.

  In still another aspect, the present invention provides a first circuit member having a first substrate and a first connection terminal provided on the first substrate, and disposed opposite to the first circuit member. The circuit connection material is disposed between the second substrate and the second circuit member having the second connection terminal provided on the second substrate, and the whole is heated and pressurized in that state, The present invention relates to a method of manufacturing a connection body to which a circuit member is connected, which includes a step of electrically connecting and bonding a first circuit member and a second circuit member with an adhesive layer formed of a circuit connection material.

  Said 1st board | substrate and / or 2nd board | substrate are flexible substrates containing a thermoplastic resin. The adhesive layer is a layer formed from the circuit connection material according to the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, when connecting the circuit member which has a flexible substrate by the circuit connection material containing electroconductive particle, damage to the electrode on a flexible substrate can fully be prevented. For example, according to the present invention, it is possible to reduce the occurrence of breakage and cracking of the electrodes on the flexible substrate during circuit connection. Further, by optimizing the size and density of the conductive particles, high-resolution circuit connection can be performed while ensuring a good connection state and connection reliability.

It is sectional drawing which shows typically the connection part of the connection body of an Example and a comparative example. It is sectional drawing which shows typically the connection part of the connection body of a reference example.

  Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments. All the configurations described in the present specification can be arbitrarily combined without departing from the spirit of the present invention. For example, the upper and lower limits of the numerical ranges described in this specification, and numerical values arbitrarily selected from the numerical values described in the examples are used as the upper and lower limits, and the numerical ranges relating to various characteristics are defined. can do.

  The circuit connection material according to the present embodiment is a composition containing an insulating adhesive and conductive particles.

  The insulating adhesive may be a thermoplastic material used for an insulating sheet or the like, or may be a curable resin that is cured by heat or light. Since it is excellent in heat resistance and moisture resistance after connection, a curable resin can be used as an insulating adhesive. Among them, the epoxy adhesive has characteristics such that it can be cured for a short time, has good connection workability, and has excellent adhesion due to its molecular structure.

  The epoxy adhesive mainly contains, for example, an epoxy resin such as a polymer epoxy resin, a solid epoxy resin, and a liquid epoxy resin. The epoxy adhesive may optionally contain resins such as phenoxy resin, polyurethane, polyester, NBR and rubber, various modifiers such as curing agents and coupling agents, and additives such as catalysts.

Epoxy resins include bisphenol type epoxy resins derived from epichlorohydrin and bisphenol A, F, AD, etc., epoxy novolac resins derived from epichlorohydrin and phenol novolac or cresol novolac, naphthalene type epoxy resins containing a naphthalene ring, glycidylamine , Various epoxy compounds having two or more glycidyl groups in one molecule, such as glycidyl ester, biphenyl type epoxy resin, and alicyclic epoxy resin. These may be used alone or in combination of two or more. Epoxy resin, impurity ions (Na ^+, C1 ^-, etc.), and the concentration of such hydrolyzable chlorine is preferred in order to prevent electromigration of high purity product was reduced to 300ppm or less.

  The curing agent may be, for example, imidazole, hydrazide, boron trifluoride-amine complex, sulfonium salt, amine imide, diaminomaleonitrile, melamine and derivatives thereof, polyamine salt or dicyandiamide, and modified products thereof. It may be. These are used alone or in combination of two or more. These are anionic or cationic polymerizable catalyst-type curing agents and are easy to obtain fast curability. Moreover, in the case of these hardening | curing agents, the necessity of a chemical equivalent consideration is small. Other examples of the curing agent include polyaddition type curing agents such as polyamines, polymercaptans, polyphenols, and acid anhydrides. A polyaddition type curing agent and a catalyst type curing agent can be used in combination.

  An insulating adhesive containing secondary amines, imidazoles, or both, which are anionic polymerization type catalyst type curing agents, and an epoxy resin is several tens of seconds to several hours at a medium temperature of about 160 ° C. to 200 ° C. Since it hardens | cures by a certain amount of heating, pot life (pot life) is comparatively long. As the cationic polymerization type catalyst-type curing agent, a photosensitive onium salt that cures the resin by energy ray irradiation, such as an aromatic diazonium salt and an aromatic sulfonium salt, can be mainly used. Catalytic curing agents that are activated by heat to cure the epoxy resin include aliphatic sulfonium salts. This type of curing agent is characterized by rapid curing.

  A microencapsulated curing agent obtained by coating these curing agents with a polymer material such as polyurethane or polyester, a metal thin film such as Ni or Cu, or an inorganic material such as calcium silicate has a pot life. Can be extended.

  Insulating adhesives include, for example, fillers, softeners, accelerators, anti-aging agents, colorants, flame retardants, dielectric materials, thixotropic agents, coupling agents, phenol resins, melamine resins, and isocyanates. You may contain the additional component chosen from a hardening | curing agent.

  The circuit connection material may be in the form of a film from the viewpoint of handleability. Examples of the film forming material that can be contained in the circuit connection material include epoxy resin, acrylic resin, polyurethane, and rubber. In order to obtain high reliability as a circuit connection material, a phenoxy resin can be used. The phenoxy resin corresponds to a high molecular weight epoxy resin having a weight average molecular weight of 10,000 or more determined by high performance liquid chromatography (HPLC). Similar to the epoxy resin, the phenoxy resin includes bisphenol A type, AD type, and AF type. The phenoxy resin is compatible with the epoxy resin because of its similar structure, and also has good adhesion. The larger the molecular weight of the film-forming material, the easier the film-forming property is obtained, and the melt viscosity that affects the fluidity during connection can be set in a wide range. From the standpoints of melt viscosity and compatibility with other resins, the weight average molecular weight may be 10,000 to 80,000, or 20,000 to 60,000. The resin as the film forming material has a polar group such as a hydroxyl group and a carboxyl group, so that compatibility with the epoxy resin is improved, and a film having a uniform appearance and characteristics can be obtained. It is also possible to obtain a short time cure by promotion. 20-80 mass% may be sufficient with respect to the whole insulating adhesive from the point of acceleration | stimulation of film formation property and hardening reaction. In order to adjust the melt viscosity and the like, a styrene resin and an acrylic resin may be mixed as appropriate.

  Film forming materials are, for example, 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 It may be at least one resin from the group consisting of a resin, a polyimide resin, and a polyester urethane resin. Adhesion can be further improved by a resin having a functional group such as a hydroxyl group. Further, these resins (polymers) may be modified with radically polymerizable functional groups.

  The insulating adhesive can contain a curing agent that generates free radicals by heating or light, and a radical polymerizable substance.

  A curing agent that generates free radicals by heating or light (hereinafter, also referred to as “free radical generator”) is decomposed by heating to generate free radicals. The free radical generator is, for example, a peroxide compound or an azo compound. The free radical generator is appropriately selected according to the intended connection temperature, connection time, pot life, and the like. From the viewpoint of high reactivity and pot life, the free radical generator may be an organic peroxide having a half-life of 10 hours at a temperature of 40 ° C. or more and a half-life of 1 minute at a temperature of 180 ° C. or less. In this case, the amount of the curing agent that generates free radicals by heating or light may be about 0.05 to 10% by mass or 0.1 to 5% by mass based on the mass of the insulating adhesive. .

  The curing agent that generates free radicals by heating or light is, for example, at least one compound selected from diacyl peroxide, peroxydicarbonate, peroxyester, peroxyketal, dialkyl peroxide, and hydroperoxide. May be. In order to suppress corrosion of the connection terminals of the circuit member, a free radical generator selected from peroxyesters, dialkyl peroxides and hydroperoxides can be used. Peroxyesters that can provide high reactivity can also be used.

  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-methylethylperoxyneodecanoate, 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, and 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 and 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, and t. -Butyl cumyl peroxide is mentioned.

  Examples of the hydroperoxide include diisopropylbenzene hydroperoxide and cumene hydroperoxide.

  These curing agents that generate free radicals by heating or light can be used alone or in combination of two or more. A decomposition accelerator, an inhibitor and the like may be combined with a free radical generator.

  The radical polymerizable substance is a substance having a functional group that is polymerized by radicals. The radically polymerizable substance is selected from, for example, acrylate, methacrylate, and maleimide compounds.

  Examples of the acrylate and methacrylate include urethane acrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, 2-hydroxy-1,3-diaacryloxypropane, 2,2-bis [4- (acryloxymethoxy) phenyl] propane, 2,2-bis [4- (acryloxypolyethoxy) phenyl] propane, dicyclo Pentenyl acrylate, tricyclodecanyl acrylate, bis (acryloxyethyl) isocyanurate, ε-caprolactone modified tris (a Rirokishiechiru) isocyanurate, and tris (acryloyloxyethyl) isocyanurate.

  These radically polymerizable substances can be used singly or in combination of two or more. The insulating adhesive according to the present embodiment may contain at least one radical polymerizable substance having a viscosity at 25 ° C. of 100,000 to 1,000,000 mPa · s. The insulating adhesive may contain a radical polymerizable substance having a viscosity (25 ° C.) 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.

  By using urethane acrylate or urethane methacrylate among radically polymerizable substances, particularly excellent adhesiveness can be obtained. A radically polymerizable substance having a glass transition temperature (Tg) of 100 ° C. or higher alone can be used in combination with urethane acrylate or urethane methacrylate after being crosslinked with an organic peroxide used to improve heat resistance. . Examples of such radically polymerizable substances include compounds having a dicyclopentenyl group, a tricyclodecanyl group, a triazine ring, or a combination thereof. In order to obtain even better characteristics, a radical polymerizable substance having a tricyclodecanyl group or a triazine ring can also be used.

  The insulating adhesive may contain a polymerization inhibitor such as hydroquinone or methyl ether hydroquinone as necessary.

  When the insulating adhesive contains a radical polymerizable substance having a phosphate ester structure in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the total amount of the radical polymerizable substance, the adhesive strength to the surface of an inorganic substance such as a metal can be obtained. It can improve. From the same point of view, this amount may be 0.5-5 parts by weight. The radically polymerizable substance having a phosphoric ester structure is obtained as a reaction product of phosphoric anhydride and 2-hydroxyl (meth) acrylate, for example. Specific examples include 2-methacryloyloxyethyl acid phosphate and 2-acryloyloxyethyl acid phosphate. These can be used singly or in combination of two or more.

  The maleimide compound has, for example, two or more maleimide groups. Examples of maleimide compounds include 1-methyl-2,4-bismaleimidebenzene, N, N′-m-phenylenebismaleimide, N, N′-P-phenylenebismaleimide, and N, N′-m-toluylenebis. Maleimide, N, N′-4,4-biphenylenebismaleimide, 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 bismaleimide, 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 and 2,2-bis [4- (4-maleimidophenoxy) phenyl] It may be at least one compound selected from hexafluoropropane. These may be used alone or in combination of two or more. You may use together a maleimide compound and allyl compounds, such as allyl phenol, allyl phenyl ether, and allyl benzoate.

  The circuit connecting material can also contain a filler, a softener, an accelerator, an anti-aging agent, a colorant, a flame retardant, a thixotropic agent, a coupling agent, a phenol resin, a melamine resin, isocyanates, and the like.

  When the circuit connection material contains a filler, connection reliability and the like can be further improved. The maximum diameter of the filler may be less than the particle diameter of the conductive particles. The amount of filler may be 5 to 60% by volume. When the amount of the filler exceeds 60% by volume, the reliability improvement effect may be saturated.

  The coupling agent may be, for example, a compound having 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. According to the compound having these groups, the adhesiveness of the insulating adhesive can be improved.

K value (K20) when the conductive particles contained in the circuit connecting material are compressed and displaced by 20% of the diameter, in other words, K values when the conductive particles are compressed and deformed until the deformation rate becomes 20%. 0.20 to 3.2 GPa (20 to 320 kgf / mm ² ) may be sufficient as (K20) (the deformation rate is the ratio of displacement to the diameter of the conductive particles). K20 may be 0.29 to 2.4 GPa (30 to 240 kgf / mm ² ).

The K value (K40) when this conductive particle is compressed and displaced by 40% of its diameter is 0.29 to 3.4 GPa (30 to 350 kgf / mm ² ) or 0.39 to 1.9 GPa (40 to 190 kgf / mm). mm ² ).

The compression hardness K value is an index of the softness of the conductive particles. The K value of the conductive particles is set at a stage temperature of 200 ° C. using a micro-compression tester, and the conductive particles are compressed at a rate of 0.33 mN / sec using a flat indenter. From the line, when the load F (kgf), displacement S (mm), particle radius (mm) R, elastic modulus E (kgf / mm ² ), Poisson's ratio σ, the compression formula of elastic sphere (F = (2 ^{1 /} 2/3)) · (S ^3/2 ) · (E · R ^1/2 ) / (1-σ ² )): K = E / (1-σ ² ) = (3/2 ^{1 / 2} ) · F · (S ^−3/2 ) · (R ^−1/2 ). Further, assuming that the deformation rate X (%) and the sphere diameter D (μm), the K value can be obtained by the equation: K = 3000 F / (D ² · X ^3/2 ) * 10 ⁶ . The deformation rate X is calculated by the formula: X = (S / D) × 100. As a planar indenter for K value measurement, a prismatic diamond indenter having a square bottom with a side of 50 μm can be used. The maximum test load in the compression test is set to 50 mN, for example.

  The compression recovery rate of the conductive particles may be 1 to 90%, or 10 to 60%. The compression recovery rate of the conductive particles is measured using a micro compression tester. The compression recovery rate is defined as the ratio of the amount of displacement until the load of 5 mN is applied after the compression tester detects the contact of particles to the amount of displacement after the load is released. The stage temperature at the time of measuring the recovery rate is set to 200 ° C.

  The conductive particles having the K value and the compression recovery rate as described above have, for example, a configuration according to an embodiment described below.

  The electroconductive particle which concerns on this embodiment has a metal layer which coat | covers a plastic particle and this plastic particle. The metal layer does not need to cover the entire surface of the plastic particle, and may cover a part of the surface of the plastic particle.

  The metal layer includes, for example, various metals selected from the group consisting of Ni, Ni / Au, Ni / Pd, Cu, and NiB. The metal layer may be a thin film produced by plating, vapor deposition, sputtering, or the like. From the viewpoint of improving insulation, the conductive particles may have a layer (insulating resin layer) of an insulating material such as silica or acrylic resin covering the metal layer outside the metal layer.

  The average diameter of the plastic particles may be 1 to 15 μm. From the viewpoint of high-density mounting, the diameter of the plastic particles may be 1 to 5 μm on average. From the viewpoint of maintaining the connection state more stably when there are variations in the surface irregularities of the electrodes, the diameter of the plastic particles may be 2 to 5 μm on average.

  The plastic particles include, for example, resins selected from acrylic resins such as polymethyl methacrylate and polymethyl acrylate, polyolefin resins such as polyethylene, polypropylene, polyisobutylene and polybutadiene, and polystyrene resins.

  From the viewpoint of easy control of the compression hardness K value and the compression recovery rate, plastic particles made of a resin obtained by polymerizing one type of polymerizable monomer having an ethylenically unsaturated group, or ethylenically unsaturated Plastic particles made of a resin obtained by copolymerizing two or more kinds of polymerizable monomers having a saturated group can be used. When two or more kinds of polymerizable monomers having an ethylenically unsaturated group are copolymerized to obtain plastic particles, a non-crosslinkable monomer and a crosslinkable monomer are used in combination, and their copolymerization ratio By appropriately adjusting the type, the compression hardness K value and the compression recovery rate of the plastic particles can be easily controlled. As said non-crosslinkable monomer and said crosslinkable monomer, the monomer described in Unexamined-Japanese-Patent No. 2004-165019 can be used, for example.

  The density of the conductive particles contained in the circuit connection material is determined according to the definition of the electrodes to be connected. The density of the conductive particles is usually 1 to 50% by volume with respect to 100% by volume of the insulating adhesive. From the viewpoint of insulation and manufacturing cost, the density of the conductive particles may be 1 to 30% by volume.

  The film-like circuit connecting material (anisotropic conductive adhesive film) is, for example, a step of preparing a coating liquid by dissolving the above-mentioned insulating adhesive and conductive adhesive in a solvent or dispersing them in a dispersion medium Then, this coating solution is applied onto a releasable substrate such as a release paper, or impregnated into a substrate such as a nonwoven fabric, and the coating solution is dried below the active temperature of the curing agent, and the solvent or dispersion And a step of removing the liquid. By using a mixed solvent of an aromatic hydrocarbon type and an oxygen-containing type as the solvent, the solubility of the material can be improved. When the SP value of the oxygen-containing solvent is 8.1 to 10.7, the latent curing agent can be particularly effectively protected. This oxygen-containing solvent is, for example, acetate. The boiling point of the solvent may be 150 ° C. or lower. When the boiling point exceeds 150 ° C., a high temperature is required for drying. Since the drying temperature is close to the activation temperature of the latent curing agent, the potential decreases, and at low temperatures, the workability during drying tends to decrease. Therefore, the boiling point of the solvent may be 60 to 150 ° C or 70 to 130 ° C.

  The film-like circuit connection material may have multiple adhesive layers. For example, an anisotropic conductive adhesive having a two-layer structure composed of an adhesive film containing conductive particles (conductive pattern layer) for imparting anisotropic conductivity and an insulating layer containing no conductive material An anisotropic conductive adhesive film having a three-layer structure composed of a film or an adhesive film containing conductive particles (conductive pattern) and an insulating layer provided on both sides thereof and containing no conductive material It can be used as a circuit connection material. The conductive particles (conductive pattern) can exist in a plurality of layers.

  These anisotropic conductive adhesive films having a multi-layer structure are advantageous for electrode connection arranged at a narrow pitch because conductive particles (conductive pattern) can be efficiently arranged on the electrodes to be connected. In consideration of adhesiveness with the circuit member, the circuit connection material can be multilayered by laminating an adhesive film excellent in adhesiveness to each circuit member to be connected.

  The circuit connection material according to the present embodiment can be used to electrically connect electrodes via conductive particles by reducing the viscosity by heating at 170 ° C. or lower for 10 seconds, for example. A storage elastic modulus E ′ at a frequency of 10 Hz at 40 ° C. of a cured body (adhesive layer) formed by heating the circuit connecting material according to the present embodiment at 120 ° C. or more and 170 ° C. or less for 10 seconds has a value of 0.5-2. It may be 5 GPa.

  The circuit connection material according to the present embodiment is disposed so as to face the first circuit member, the first circuit member having the first substrate and the first connection terminal provided on the first substrate. The circuit connection material is disposed between the second substrate and the second circuit member having the second connection terminal provided on the second substrate, and the whole is heated and pressurized in that state. The first circuit member and the second circuit member are electrically connected and bonded together by an adhesive layer formed of a circuit connection material, and used for a method of connecting circuit members.

  Said 1st board | substrate, a 2nd board | substrate, or both are flexible boards containing a thermoplastic resin. The flexural modulus of the flexible substrate is, for example, 10 GPa or less.

  The flexible substrate includes, for example, polyimide (PI) having relatively high heat resistance and a thermoplastic resin selected from polyethylene terephthalate (PET), polycarbonate (PC), and polyethylene naphthalate (PEN) having relatively low heat resistance. Having an organic substrate.

  The flexible substrate further has one or more layers selected from a modified film such as a hard coat and a protective film for improving optical and mechanical properties, which are formed on the surface of the organic base material. It may be. As a reinforcing material for facilitating the handling and conveyance of the substrate, a composite material having a glass base material, SUS, and the like disposed by bonding or coating can be used as a flexible substrate.

  The thickness of the flexible substrate may be about 10 to 200 μm or about 10 to 125 μm from the standpoint of maintaining the strength as a single film and ensuring the bendability.

  Examples of the electrode material for forming the connection terminal provided on the flexible substrate include metals such as Ni, Al, Au, Cu, Ti, and Mo, and transparent conductors such as ITO and IZO.

  When the second substrate is a flexible substrate, the first substrate may be an IC chip or a flexible substrate. When the first substrate is an IC chip and the second substrate is a flexible substrate, a circuit connection material is used for COP (Chip on Plastic substrate) connection. When the first substrate and the second substrate are flexible substrates, a circuit connection material is used for FOP (Film on Plastic substrate) connection.

  Electronic components such as active elements such as semiconductor chips, transistors, diodes, and thyristors, and passive elements such as capacitors, resistors, and coils can be connected to the second circuit member having the flexible substrate. , A printed circuit board, a glass substrate on which ITO or the like is formed. On the electrode pad of the semiconductor chip or substrate, the bump formed by plating or the tip of the gold wire is melted with a torch or the like to form a gold ball, and after the ball is pressed onto the electrode pad, the wire is cut. Protruding electrodes such as wire bumps obtained in this way can be provided and used as connection terminals.

  Although the number of connection terminals of the circuit member may be single, usually a large number are provided. At least one set of circuit members is arranged so that at least a part of connection terminals of the circuit members are opposed to each other, and a circuit connection material is interposed between the connection terminals arranged to face each other. By heating and pressurizing in this state, the connection terminals arranged opposite to each other are electrically connected to obtain a connection body. The connection terminals arranged opposite to each other are electrically connected via conductive particles.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

Example 1
Urethane acrylate (product name: UA-5500T, manufactured by Shin-Nakamura Chemical Co., Ltd.) 20 parts by mass, bis (acryloxyethyl) isocyanurate (product name: M-215, manufactured by Toagosei Co., Ltd.) 15 mass Parts, dimethylol tricyclodecane diacrylate (product name: DCP-A, manufactured by Kyoeisha Chemical Co., Ltd.) 5 parts by mass and 2-methacryloyloxyethyl acid phosphate (product name: P-2M, manufactured by Kyoeisha Chemical Co., Ltd.) 1 Mass parts, 8 parts by mass of benzoyl peroxide (product name: Nyper BMT-K, manufactured by NOF Corporation) and polyester urethane resin (product name: UR4800, manufactured by Toyobo Co., Ltd.) mixed solvent of toluene / methyl ethyl ketone = 50/50 40 parts by mass of a 40% by mass polyester urethane resin solution obtained by dissolution in the mixture, stirred, and vine To obtain a solution of a resin (insulating adhesive). In this binder resin solution, an average particle diameter of 3 μm having polystyrene particles as nuclei, a nickel layer having a thickness of 0.2 μm and a gold layer having a thickness of 0.04 μm provided in order from the inside covering the surface of the polystyrene particles. The conductive particles were dispersed at a rate of 10% by volume with respect to the insulating adhesive. K value (K20) at 20% compression deformation of conductive particles is 0.74 GPa (75 kgf / mm ² ), K value (K40) at 40% compression deformation is 0.66 GPa (67 kgf / mm ² ), compression recovery The rate was 30%. Further, silicone fine particles having an average particle diameter of 2 μm (product name: KMP-605, manufactured by Shin-Etsu Chemical Co., Ltd.) are dispersed at a ratio of 20 parts by mass with respect to 100 parts by mass of the binder resin, and the binder resin, conductive particles, and silicone are dispersed. A coating solution of a circuit connecting material containing fine particles was obtained. This coating solution is applied to a polyethylene terephthalate (PET) film (thickness 50 μm) with one surface treated using a coating device, and the coating film is dried with hot air at 70 ° C. An anisotropic conductive adhesive film (thickness 20 μm) was formed. The K value of the conductive particles was measured by performing a compression test at a maximum test load of 50 mN and a compression speed of 0.33 mN / sec using a prismatic diamond indenter having a square bottom with a side of 50 μm.

A polyimide film (elastic modulus at 25 ° C .: 5800 MPa), an SiO ₂ film (thickness 1000 mm) formed on the polyimide film, and an ITO film having a thickness of 2500 mm as an electrode provided on the SiO ₂ film A flexible substrate was prepared. An anisotropic conductive adhesive film was sandwiched between this flexible substrate and an IC chip having 12 μm × 100 μm bumps. In this state, while heating so that the anisotropic conductive adhesive film reaches a temperature of 160 ° C., the whole is pressed at a pressure of 100 MPa per total connection area for 5 seconds to connect the flexible substrate and the IC chip. A connected body was obtained.

  When the cross section of the obtained connection body was observed and the amount of deformation of the connection terminal (ITO film) in contact with the conductive particles was measured, it was 0.5 μm or less. FIG. 1A is a cross-sectional view schematically showing a connection portion of the connection body of the first embodiment. As shown in FIG. 1, an indentation is formed on the connection terminal (ITO film) 1 on the flexible substrate (polyimide film) 10 by contact with the conductive particles 5, and the connection terminal 1 and the bump 3 of the ITO chip are formed. It was confirmed that continuity was ensured. The depth of the concave portion of the ITO film formed by contact with the conductive particles was defined as the amount of deformation of the electrode. This amount of deformation is the depth of the portion of the recess where the displacement from the electrode surface of the portion that is not in contact with the conductive particles (the portion other than the recess) is the largest.

Example 2
100 g of bisphenol F-type phenoxy resin was dissolved in a mixed solvent of toluene and ethyl acetate having a mass ratio of 50:50 to obtain a bisphenol F-type phenoxy resin solution having a concentration of 60% by mass. Further, 50 g of bisphenol A / F copolymer phenoxy resin is dissolved in a mixed solvent of toluene and ethyl acetate having a mass ratio of 50:50 to obtain a bisphenol A / F copolymer phenoxy resin solution having a concentration of 45% by mass. It was.

  The obtained two phenoxy resin solutions were mixed to obtain a mixed solution. A liquid epoxy resin was added to this mixed solution. The amount of the liquid epoxy resin was adjusted so that the mass ratio of bisphenol F type phenoxy resin: bisphenol A / F copolymer type phenoxy resin: liquid epoxy resin was 30:30:40.

  In 100 g of the obtained solution, the same conductive particles as in Example 1 were dispersed at a ratio of 10% by volume with respect to the insulating adhesive. Thereto was further added 2.4 g of an aromatic sulfonium salt as a latent curing agent to obtain a coating solution. This coating solution is applied to a polyethylene terephthalate (PET) film (thickness 50 μm) with one surface treated by using a coating device and dried with hot air at 70 ° C. for 5 minutes. A conductive adhesive film (thickness 20 μm) was formed.

  Using the produced anisotropic conductive adhesive film, a connection body in which the flexible base material and the IC chip were connected was produced in the same manner as in Example 1. When the cross section of the obtained connection body was observed and the amount of deformation of the connection terminal (ITO film) in contact with the conductive particles was measured, it was 0.5 μm or less. Circuit breaks and cracks were not observed. It was observed that indentations were formed on the connection terminals (ITO film) by contact with the conductive particles.

Comparative Example 1
Conductive particles having an average particle diameter of 3 μm having polystyrene particles as nuclei and a nickel layer having a thickness of 0.2 μm and a gold layer having a thickness of 0.04 μm provided in order from the inside covering the surface of the polystyrene particles were prepared. The conductive particles had a K value at 20% compression deformation of 3.43 GPa (350 kgf / mm ² ), a K value at 40% compression deformation of 4.02 GPa (410 kgf / mm ² ), and a compression recovery rate of 40%. there were. An anisotropic conductive adhesive film was produced in the same manner as in Example 1 except that the conductive particles were used, and a connection body between the flexible substrate and the IC chip was produced using the anisotropic conductive adhesive film.

  The cross section of the obtained connection body was observed. FIG. 1B is a cross-sectional view schematically showing a connection portion of the connection body of Comparative Example 1. When the amount of deformation of the connection terminal (ITO film) 1 in the portion in contact with the conductive particles 5 was measured, it was 1.0 μm or more, and a circuit breakage was observed.

Comparative Example 2
Conductive particles having an average particle diameter of 3 μm having polystyrene particles as nuclei and a nickel layer having a thickness of 0.2 μm and a gold layer having a thickness of 0.04 μm provided in order from the inside covering the surface of the polystyrene particles were prepared. The conductive particles had a K value at 20% deformation of 350 kgf / mm ² , a K value at 40% deformation of 410 kgf / mm ² , and a recovery rate of 40%. An anisotropic conductive adhesive film was prepared in the same manner as in Example 2 except that the conductive particles were used, and a connection body between the flexible substrate and the IC chip was prepared using the anisotropic conductive adhesive film.

  When the cross section of the obtained connection body was observed and the amount of deformation of the connection terminal (ITO film) in contact with the conductive particles was measured, it was 1.0 μm or more, and a circuit breakage was observed. .

Reference example 1
The anisotropic conductive adhesive film produced in Example 1 is made of a glass substrate having a glass plate (thickness 0.5 mm, OA-10) and an aluminum sputtered film electrode (thickness 2500 mm) formed on the glass plate. Sandwiched between a material and an IC chip having a bump of 12 μm × 100 μm, and heated for a total of 5 seconds at a pressure of 100 MPa per total connection area while heating the anisotropic conductive adhesive film to a temperature of 160 ° C. Was pressed to obtain a connection body in which the glass substrate and the IC chip were connected.

  The cross section of the obtained connection body was observed. 2A is a cross-sectional view schematically showing a connection portion of the connection body of Reference Example 1. FIG. When the amount of deformation of the connection terminal (ITO film) 1 at the portion in contact with the conductive particles 5 was measured, it was 0.1 μm or less, and no breakage or cracks in the circuit were observed. Moreover, the impression of the electrode formed with electroconductive particle used for the pass / fail determination of the connection state of a glass base material was not observable.

Reference example 2
A connection body of a glass substrate and an IC chip was prepared in the same manner as in Reference Example 1 except that the anisotropic conductive adhesive film prepared in Example 2 was used, and the cross section thereof was observed. The deformation of the electrode in contact with the conductive particles was 0.1 μm or less, and no circuit breakage was observed. The indentation of the electrode formed by the conductive particles could not be observed.

Reference example 3
2 except that the anisotropic conductive adhesive film produced in Comparative Example 1 was used, in the same manner as in Reference Example 1, and a connection body of a glass substrate and an IC chip was produced and the cross section thereof was observed. (B) is sectional drawing which shows typically the connection part of the connection body of the reference example 3. FIG. The deformation amount of the connection terminal (electrode) 1 at the portion in contact with the conductive particles 5 was 0.1 μm or less, and no circuit breakage was observed. Indentation of the electrode formed by the conductive particles 5 was observed.

Reference example 4
A connection body of the glass substrate and the IC chip was prepared in the same manner as in Reference Example 1 except that the anisotropic conductive adhesive film prepared in Comparative Example 2 was used, and the cross section thereof was observed. The deformation of the electrode in contact with the conductive particles was 0.1 μm or less, and no circuit breakage was observed. Indentations of the electrodes formed by the conductive particles were observed.

  Table 1 shows the configuration and evaluation results of each connection body produced. As shown in the table, according to the example, it was possible to perform circuit connection of the flexible base material while forming indentations without causing breakage and cracking of the circuit.

  DESCRIPTION OF SYMBOLS 1 ... Connection terminal, 3 ... Connection terminal (IC chip bump), 5 ... Conductive particle, 10 ... Flexible substrate (substrate), 20 ... Glass substrate (substrate)

Claims (6)

A first circuit member having a first substrate and a first connection terminal provided on the first substrate;
A second circuit member disposed opposite to the first circuit member and having a second substrate and a second connection terminal provided on the second substrate;
An adhesive layer provided between the first circuit member and the second circuit member, electrically connecting and bonding the first circuit member and the second circuit member;
The first substrate is a flexible substrate containing an IC chip or a thermoplastic resin,
The second substrate is a flexible substrate containing a thermoplastic resin,
The adhesive layer contains an insulating adhesive and conductive particles dispersed in the insulating adhesive, the conductive particles have plastic particles and a metal layer covering the plastic particles, A connection body, which is a layer formed of a circuit connection material , having a compression hardness K value of 0.20 to 3.2 GPa when the conductive particles are compressed and displaced by 20% of the diameter thereof . The connection body according to claim 1, wherein the thermoplastic resin is at least one selected from the group consisting of polyimide, polyethylene terephthalate, polycarbonate, and polyethylene naphthalate. The connection body according to claim 1 or 2, wherein a compression hardness K value when the conductive particles are compressed and displaced by 40% of the diameter thereof is 0.29 to 3.4 GPa. The connection body as described in any one of Claims 1-3 whose compression recovery rate of the said electroconductive particle is 1 to 90%. 5. The storage elastic modulus E ′ at a frequency of 10 Hz at 40 ° C. after being heated for 10 seconds at 170 ° C. or less of the circuit connection material is 0.5 to 2.5 GPa. Connection body . The connection body according to claim 1, wherein the circuit connection material is an anisotropic conductive adhesive.

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