Adhesive composition, anisotropic conductive film, connection structure, and method for manufacturing the connection structure

Abstract

To provide an adhesive composition usable also for connection that requires higher adhesion strength due to substrate difference such as FOG or COG mounting, and excellent in dispersibility of conductive particles and connection reliability.SOLUTION: An adhesive composition of the present invention comprises a binder composition containing a polymerizable component and a film-forming component, a polymerization initiator, conductive particles having a particle size of 1 μm or more and 10 μm or less, an insulating filler having a particle size of 5% or less of the conductive particles, and a silane-coupling agent, wherein the blending amount of the insulating filler is 85 mass% or more and 200 mass% or less of the conductive particles.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an adhesive composition, an anisotropic conductive film, a connection structure, and a method for producing the connection structure. [Background technology]

[0002] Adhesive compositions such as anisotropic conductive paste (ACP) and film-like materials (anisotropic conductive films) such as anisotropic conductive films (ACF) are widely used as means for bonding electronic components to circuit boards, etc. For example, anisotropic conductive films are used to bond and electrically connect various terminals together, such as when connecting terminals of a flexible printed circuit (FPC) to terminals of a glass substrate of an LCD panel (so-called FOG), and when connecting a driving IC to a glass substrate (so-called COG).

[0003] When connecting FOG, COG, etc. using anisotropic conductive films, low-temperature, short-time compression bonding is required to minimize damage to the substrate, and this is achieved by using a radical polymerizable compound and a radical polymerization initiator as adhesive components (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-185399 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, as LCD panels have become more precise, the spacing between connected wiring has become narrower, and the required connection area has become smaller. To meet this demand, it is necessary to increase the amount of conductive particles added to the anisotropic conductive film. On the other hand, when a coupling agent is added to an anisotropic conductive film to improve adhesion when bonding different materials such as FOG and COG, the adhesion between the conductive particles also improves, which can lead to problems such as short circuits caused by the aggregation of the conductive particles.

[0006] An object of the present invention is to provide an adhesive composition that can be used for bonding substrates that require high adhesive strength, such as FOG and COG mounting, and that has excellent conductive particle dispersibility and connection reliability. [Means for solving the problem]

[0007] As a result of extensive research into the above problems, the present inventors have found that the above problems can be solved by an adhesive composition having the following composition, and have thus completed the present invention.

[0008] That is, the present invention includes the following. [1] A binder composition containing a polymerizable component and a film-forming component; a polymerization initiator; Conductive particles having a particle diameter of 1 μm or more and 10 μm or less; an insulating filler having a particle size of 5% or less of the conductive particles; a silane coupling agent; wherein the amount of the insulating filler mixed is 85% by mass or more and 200% by mass or less of the conductive particles. [2] The adhesive composition according to claim 1, wherein the insulating filler is spherical. [3] An anisotropic conductive film comprising the adhesive composition according to claim 1 or 2. [4] A connection structure in which a first electronic component and a second electronic component are connected by the anisotropic conductive film described in claim 3. [5] A method for manufacturing a connection structure, comprising a step of pressure-bonding a first electronic component and a second electronic component with the anisotropic conductive film described in claim 3 interposed therebetween. [Effects of the Invention]

[0009] According to the present invention, an adhesive composition can be provided that can be used for bonding that requires high adhesive strength, such as FOG and COG mounting, and that has excellent dispersibility of conductive particles and connection reliability. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in detail below with reference to preferred embodiments thereof. The present invention is not limited to the following description, and each component can be appropriately modified within the scope of the present invention.

[0011] [Adhesive composition] The adhesive composition of the present invention comprises a binder composition containing a polymerizable component and a film-forming component, a polymerization initiator, conductive particles having a particle diameter of 1 μm or more and 10 μm or less, an insulating filler having a particle diameter of 5% or less of the conductive particles, and a coupling agent, wherein the amount of the insulating filler mixed is 85% by mass or more and 200% by mass or less of the conductive particles. Each component will be described in detail below.

[0012] <Binder composition> The adhesive composition of the present invention comprises a binder composition that includes a polymerizable component and a film-forming component.

[0013] (Polymerizable component) The polymerizable component used in the adhesive composition of the present invention may be, for example, a thermal radical polymerization type, a thermal cationic polymerization type, or a thermal anionic polymerization type. A thermal radical polymerization type polymerizable component is preferred, as it allows pressure bonding at low temperature in a short time.

[0014] An example of a thermal radical polymerization type polymerizable component is (meth)acrylate. As the (meth)acrylate, a monofunctional (meth)acrylate, a bifunctional (meth)acrylate, or a trifunctional or higher functional (meth)acrylate can be used. In this specification, the term (meth)acrylate is used to encompass both acrylic acid esters (acrylates) and methacrylic acid esters (methacrylates).

[0015] Examples of monofunctional (meth)acrylates include polyalkylene glycol ester monomers, alkyl (meth)acrylates having a linear or branched alkyl group, etc. Examples of polyalkylene glycol ester monomers include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polybutylene glycol mono(meth)acrylate, etc.

[0016] Examples of bifunctional (meth)acrylates include tricyclodecane dimethanol di(meth)acrylate, dimethylol-tricyclodecane di(meth)acrylate, bisphenol A-EO modified di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 2-hydroxy-3-acryloxypropyl (meth)acrylate, propoxylated bisphenol A di(meth)acrylate, diethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, polyethylene glycol (200) di(meth)acrylate, Examples of such di(meth)acrylates include tetraethylene glycol di(meth)acrylate, polyethylene glycol (400) di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, alkoxylated hexanediol di(meth)acrylate, alkoxylated cyclohexanedimethanol di(meth)acrylate, ethoxylated (4) bisphenol A-di(meth)acrylate, ethoxylated (10) bisphenol A-di(meth)acrylate, polyethylene glycol (600) di(meth)acrylate, alkoxylated neopentyl glycol di(meth)acrylate, dioxane glycol di(meth)acrylate, and isocyanuric acid EO-modified di(meth)acrylate.

[0017] Examples of trifunctional or higher functional (meth)acrylates include isocyanuric acid EO-modified tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, pentaerythritol tri(meth)acrylate, EO-modified pentaerythritol tri(meth)acrylate, ε-caprolactone-modified tris(acryloxyethyl)(meth)acrylate, ethoxylated (20) trimethylolpropane tri(meth)acrylate, propoxylated (3) trimethylolpropane tri(meth)acrylate, and propoxylated (6) trimethylolpropane tri(meth)acrylate. Examples of the polymerizable component include pantaerythritol tri(meth)acrylate, ethoxylated (9) trimethylolpropane tri(meth)acrylate, propoxylated (3) glyceryl tri(meth)acrylate, ethoxylated (4) pentaerythritol tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, EO-modified dipentaerythritol penta(meth)acrylate, and urethane (meth)acrylates having three to nine functionalities. The polymerizable component may be used alone or in combination of two or more.

[0018] In the adhesive composition of the present invention, the content of the polymerizable component is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 18% by mass or more, and even more preferably 20% by mass or more, based on 100% by mass of the nonvolatile components in the adhesive composition. The upper limit of the content is not particularly limited, but is preferably 60% by mass or less, more preferably 55% by mass or less or 50% by mass or less.

[0019] (Components for film formation) The film-forming component is not particularly limited as long as it has film-forming ability. The film-forming component may be appropriately selected depending on the purpose, and examples thereof include phenoxy resin, epoxy resin, polyvinyl acetal resin, unsaturated polyester resin, saturated polyester resin, urethane resin, butadiene resin, polyimide resin, polyamide resin, and polyolefin resin. The film-forming component may be used alone or in combination of two or more. Among these, phenoxy resins can be preferably used from the viewpoints of film-forming properties, processability, and connection reliability.

[0020] From the viewpoint of film-forming properties, the polystyrene-equivalent weight-average molecular weight (Mw) of the film-forming component is preferably 10,000 or more, more preferably 15,000 or more, and even more preferably 20,000 or more. The upper limit of Mw is not particularly limited, but it may be preferably 80,000 or less, more preferably 70,000 or less, or even 60,000 or less. It may be appropriately selected depending on the other ingredients and the intended use. It is preferable for the film-forming component to contain a phenoxy resin with a Mw of 50,000 or less, since this can significantly prevent the occurrence of lifting at the connection points of the connection structure even after reliability testing under high-temperature, high-humidity environments. The polystyrene-equivalent Mw of the film-forming component can be measured by gel permeation chromatography (GPC) and calculated using a calibration curve of standard polystyrene.

[0021] The content of the film-forming component in the adhesive composition is not particularly limited and may be determined appropriately depending on the purpose, but is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, when the non-volatile components in the adhesive composition are taken as 100% by mass. The upper limit of the content is not particularly limited, but is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less.

[0022] <Polymerization initiator> The adhesive composition of the present invention contains a polymerization initiator. The polymerization initiator is selected according to the polymerizable component used. If the polymerizable component is a thermal radical polymerization type, a radical polymerization initiator is used. If the polymerizable component is a thermal cationic polymerization type, a cationic polymerization initiator is used. If the polymerizable component is a thermal anionic polymerization type, an anionic polymerization initiator is used.

[0023] An organic peroxide can be used as the radical polymerization initiator. The one-minute half-life temperature of the organic peroxide is preferably 130°C or lower, more preferably 80°C or higher and 120°C or lower. The one-minute half-life temperature is lower than the compression bonding temperature, and if the temperature is too high, it becomes difficult to achieve a high reaction rate. Furthermore, if the one-minute half-life temperature is too low, the room temperature storage property decreases.

[0024] Examples of organic peroxides used as radical polymerization initiators include dilauroyl peroxide (1-minute half-life temperature: 116°C), benzoyl peroxide (1-minute half-life temperature: 130°C), di(4-methylbenzoyl) peroxide (1-minute half-life temperature: 128°C), 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (1-minute half-life temperature: 124°C), di(3,5,5-trimethylhexanoyl) peroxide (1-minute half-life temperature: 113°C), t-butylperoxypivalate (1-minute half-life temperature: 110°C), and t-hexylperoxypivalate (1-minute half-life temperature: 1 09°C), t-butyl peroxyneoheptanoate (1-minute half-life temperature: 105°C), t-butyl peroxyneodecanoate (1-minute half-life temperature: 101°C), di(2-ethylhexyl)peroxydicarbonate (1-minute half-life temperature: 91°C), di(4-t-butylcyclohexyl)peroxydicarbonate (1-minute half-life temperature: 92°C), 1,1,3,3-tetramethylbutyl peroxyneodecanoate (1-minute half-life temperature: 85°C), di-sec-butyl peroxydicarbonate (1-minute half-life temperature: 85°C), cumyl peroxyneodecanoate (1-minute half-life temperature: 85°C), etc. The polymerization initiators may be used alone or in combination of two or more.

[0025] The amount of the polymerization initiator is preferably 1 part by mass or more and 30 parts by mass or less, and more preferably 5 parts by mass or more and 20 parts by mass or less, per 100 parts by mass of the polymerizable component. If the content of the polymerization initiator is too low, the reactivity tends to decrease, and if it is too high, the product life tends to decrease.

[0026] <Conductive particles> The adhesive composition of the present invention contains conductive particles. By including the conductive particles, the adhesive composition and a film-like product thereof can be used as a conductive paste and a conductive film, or an anisotropic conductive paste and an anisotropic conductive film.

[0027] The conductive particles may be any known conductive particles used in anisotropic conductive films. Examples of conductive particles include particles of metals such as nickel, iron, copper, aluminum, tin, lead, chromium, cobalt, silver, and gold; particles of alloys of these metals; and coated particles of metal oxides, carbon, graphite, glass, ceramics, and resins. When using metal-coated resin particles, examples of the resin particle material include epoxy resin, phenolic resin, acrylic resin, acrylonitrile-styrene (AS) resin, benzoguanamine resin, divinylbenzene-based resin, and styrene-based resin. To avoid the risk of short circuits between terminals, the conductive particles may be further insulated, such as by coating the surface with an insulating thin film or by attaching insulating particles to the surface, as long as this does not impair the electrical conductivity after connection. These conductive particles may be used alone or in combination of two or more types.

[0028] The conductive particles have an average particle size of 1 μm or more and 10 μm or less, preferably 2 μm or more and 7 μm or less. The average particle size of the conductive particles can be determined, for example, by observing the particles with a scanning electron microscope (SEM), measuring the particle sizes of a plurality of conductive particles (n≧10), and calculating the average value. Alternatively, the average particle size can be measured (N=1000 or more) using an image particle size analyzer (for example, FPIA-3000 (Malvern Instruments)).

[0029] The content of the conductive particles in the adhesive composition is not particularly limited and may be determined appropriately depending on the purpose, but is preferably 1% by mass or more, more preferably 2% by mass or more. From the viewpoint of obtaining the desired anisotropic conductivity, the upper limit of the content of the conductive particles is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less.

[0030] <Silane coupling agent> The adhesive composition of the present invention contains a silane coupling agent. By including the silane coupling agent, the interfacial adhesion with inorganic materials can be improved. Examples of silane coupling agents include those having a vinyl group, an acrylic group, a methacrylic group, an epoxy group, a mercapto group, an amino group, an isocyanate group, a ureido group, or an imidazole group. The silane coupling agents may be used alone or in combination of two or more.

[0031] In the adhesive composition of the present invention, the content of the silane coupling agent is preferably 0.1% by mass or more and 5% by mass or less, when the nonvolatile components in the adhesive composition are taken as 100% by mass.

[0032] <Insulating filler> The adhesive composition of the present invention contains an insulating filler having a particle size of 5% or less of the conductive particles. By including an insulating filler with a predetermined particle size, aggregation of the conductive particles can be suppressed, preventing the occurrence of short circuits. If the particle size of the insulating filler is 5% or less of the conductive particles, aggregation of the conductive particles can be suppressed, but it is preferably 4% or less. There is no particular lower limit for the particle size of the insulating filler, but from the viewpoints of handleability, ease of production, etc., it is 0.1% or more, preferably 0.5% or more.

[0033] Examples of insulating fillers include inorganic oxides such as silica, titanium oxide, aluminum oxide, calcium oxide, and magnesium oxide; inorganic hydroxides such as calcium hydroxide, magnesium hydroxide, and aluminum hydroxide; inorganic carbonates such as calcium carbonate, magnesium carbonate, zinc carbonate, and barium carbonate; inorganic sulfates such as calcium sulfate and barium sulfate; inorganic silicates such as calcium silicate; and inorganic nitrides such as aluminum nitride, boron nitride, and silicon nitride. Furthermore, the insulating filler is not limited to inorganic materials, and organic fillers can also be used. Examples of organic fillers include butadiene-based rubber particles, acrylic-based rubber particles, silicone-based rubber particles, and melamine-based particles.

[0034] The amount of insulating filler in the adhesive composition is 85% by mass or more and 200% by mass or less of the amount of conductive particles. By making the amount of insulating filler 85% by mass or more of the amount of conductive particles, aggregation of the conductive particles can be effectively suppressed. Furthermore, by making the amount of insulating filler 200% by mass or less of the amount of conductive particles, an increase in resistance value can be suppressed. The amount of insulating filler is preferably 90% by mass or more and 150% by mass or less.

[0035] The insulating filler is preferably spherical. The spherical shape improves the effect of inhibiting the aggregation of conductive particles. In this specification, "spherical" means that the ratio (aspect ratio) of the long axis (maximum length) to the short axis (shortest length) of the insulating filler is 1.5 or less. The ratio of the long axis to the short axis of the insulating filler is 1.5 or less, thereby enabling the effect of inhibiting the aggregation of conductive particles to be achieved.

[0036] The adhesive composition of the present invention may further contain other components as needed, such as known additives used in the production of adhesive compositions, such as surface modifiers, flame retardants, and colorants.

[0037] The adhesive composition of the present invention has high adhesive strength and can suppress the aggregation of conductive particles. Therefore, the adhesive composition of the present invention can prevent the occurrence of short circuits, even when used for bonding different substrates that require high adhesive strength, such as FOG mounting in which an FPC is mounted on a glass substrate or COG mounting in which an IC is mounted on a glass substrate. Furthermore, the adhesive composition of the present invention can be easily produced by mixing and stirring the constituent components using a solvent.

[0038] [Anisotropic conductive film] The adhesive composition of the present invention has good film-forming properties and can be suitably formed into an anisotropic conductive film. The present invention also includes an anisotropic conductive film made from the adhesive composition of the present invention.

[0039] The anisotropic conductive film of the present invention may consist of a single layer or multiple layers. When consisting of multiple layers, the anisotropic conductive film may include a first adhesive layer made of the adhesive composition of the present invention and a second adhesive layer made of the adhesive composition of the present invention provided on the first adhesive layer. Furthermore, a layer different from the adhesive layer of the present invention may be provided on the adhesive layer of the present invention. This layer may be sandwiched between the adhesive layers of the present invention on both sides. The layer different from the adhesive layer of the present invention may be a resin layer that is not an adhesive layer (does not contribute to adhesion). It is preferable that the layer different from the adhesive layer of the present invention is insulating.

[0040] An anisotropic conductive film can be produced, for example, by mixing the adhesive composition of the present invention with an organic solvent, if necessary, and then applying it to a release substrate and drying it to form an adhesive layer. The adhesive composition can be applied using a coating device such as a bar coater. Known coating methods for anisotropic conductive films, such as a doctor blade method, can be used. When producing an anisotropic conductive film consisting of multiple layers, the above-mentioned coating and drying steps can be repeated multiple times. Alternatively, the layers can be produced individually and then laminated using a laminate or the like.

[0041] The release substrate is not particularly limited as long as it is a film-like material that can support the anisotropic conductive film and can be peeled off from the anisotropic conductive film at the desired timing. Examples of materials that can be used for the release substrate include polyesters such as polyethylene terephthalate (PET), polyolefins such as polypropylene (PP), and plastic materials such as poly-4-methylpentene-1 (PMP) and polytetrafluoroethylene (PTFE). The release substrate may also be a substrate having a release layer on the surface that is bonded to the anisotropic conductive film, and the release layer may contain a release agent such as a silicone resin or a polyolefin resin.

[0042] The thickness of the release substrate is not particularly limited, but is preferably 100 μm or less, more preferably 80 μm or less, even more preferably 60 μm or less, and even more preferably 50 μm or less. The lower limit of the thickness of the release substrate is not particularly limited, but is preferably 8 μm or more from the viewpoint of ease of handling during slitting during production of the anisotropic conductive film.

[0043] The thickness of the anisotropic conductive film of the present invention is not particularly limited and may be determined appropriately depending on the purpose, but is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more. The upper limit of the thickness of the adhesive layer is not particularly limited, but is preferably 100 μm or less, more preferably 80 μm or less, even more preferably 60 μm or less, even more preferably 50 μm or less, and particularly preferably 40 μm or less. When multiple layers are laminated, the total thickness is used.

[0044] The anisotropic conductive film may be slit to a predetermined width. During slitting, a cover film may be provided on the exposed surface to prevent contamination of the adhesive layer by cutting chips or the like. In this case, the thickness may be selected appropriately depending on the purpose. The cover film may be a known film used when slitting the anisotropic conductive film. The cover film may be provided separately from the release substrate to prevent contamination during use as a product used for connection purposes, in addition to during the manufacturing process such as slitting. In this case, the cover film is preferably releasable, and its thickness is preferably the same as or thinner than the release substrate.

[0045] The anisotropic conductive film of the present invention has high adhesive strength and can suppress the aggregation of conductive particles, and therefore can prevent the occurrence of short circuits and the like even when used for bonding between different substrates that require high adhesive strength, such as FOG mounting for mounting an FPC on a glass substrate or COG mounting for mounting an IC on a glass substrate.

[0046] [Connection structure] The adhesive composition or anisotropic conductive film of the present invention can be used to produce a connection structure in which electronic components are bonded to each other. The present invention encompasses a connection structure in which a first electronic component and a second electronic component are connected by the adhesive composition or anisotropic conductive film of the present invention.

[0047] The first electronic component may be, for example, a general PWB, and examples thereof include rigid substrates, glass substrates, ceramic substrates, plastic substrates, and FPCs. Examples of the second electronic component include FPCs, IC chips, and semiconductor elements other than IC chips. There are no particular restrictions on the electronic component, and there are no particular restrictions on the use of the connection structure. For example, the connection structure may be used in a personal digital assistant (PDAs) or for in-vehicle electrical mounting. In the present invention, a variety of connection structures may be manufactured, including, for example, FOBs, FOGs, FOPs, FOFs, COGs, and COPs.

[0048] [Method of manufacturing the connection structure] The method for producing the connection structure of the present invention is not particularly limited as long as it is possible to produce a connection structure in which a first electronic component and a second electronic component are connected by the adhesive composition or anisotropic conductive film of the present invention. An example of a method for producing the connection structure of the present invention is shown below.

[0049] In one embodiment, the method for producing a connection structure of the present invention includes a step of pressure-bonding a first electronic component and a second electronic component with the adhesive composition or anisotropic conductive film of the present invention interposed therebetween.

[0050] First, a first electronic component is placed on a stage, and the adhesive composition or anisotropic conductive film of the present invention is applied thereon. Then, a second electronic component is placed on the stage. After the adhesive composition or anisotropic conductive film of the present invention is applied to the first electronic component placed on the stage, the first electronic component and the second electronic component are aligned so that their electrodes face each other. Pre-bonding is then performed from the second electronic component side using a crimping tool. The temperature, pressure, and time during pre-bonding can be determined appropriately depending on the specific design, and may be, for example, 60 to 80°C, 0.5 to 2 MPa, and 0.5 to 2 seconds. Pre-bonding is preferably performed prior to the main bonding described below, because it allows for more accurate alignment and connection between the electronic components (the conductive portions of each component). Pre-bonding is expected to reduce misalignment during main bonding, which requires higher pressure.

[0051] After the temporary pressure bonding, a pressure bonding tool is used to perform a final pressure bonding from the second electronic component side. The temperature, pressure, and time during the final pressure bonding may be any known conditions used when bonding electronic components using an anisotropic conductive film, and may be appropriately determined depending on the specific design. For example, even if the pressure bonding is performed at a low temperature (e.g., 160°C or less) and for a short time (e.g., 10 seconds or less), the first electronic component and the second electronic component can be bonded well.

[0052] Regardless of whether temporary or permanent bonding is performed, a buffer material (e.g., a buffer sheet) may be provided between the second electronic component and the bonding tool. The buffer material, including whether or not to use it, may be adjusted and determined appropriately depending on the combination of electronic components.

[0053] The adhesive composition or anisotropic conductive film of the present invention contains a silane coupling agent, and therefore has high adhesive strength even when bonding different substrates such as FOG and COG. Furthermore, when pressure-bonded under low-temperature, short-time conditions, for example, at 150°C, 3 MPa, and 10 seconds, a connection structure between an FPC and a glass substrate produced using the adhesive composition or anisotropic conductive film of the present invention can exhibit a high adhesive strength of 10 N / cm or more in a 90-degree peel test. [Example]

[0054] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the examples shown below. In the following description, "parts" and "%" representing amounts mean "parts by mass" and "% by mass", respectively, unless otherwise specified.

[0055] [Example 1] -Preparation of adhesive composition- 40 parts by mass of phenoxy resin (trade name: YP-50, manufactured by Nippon Steel Chemical & Materials Co., Ltd., film-forming component), 25 parts by mass of urethane acrylate (trade name: UN-5500, manufactured by Negami Chemical Industrial Co., Ltd., polymerizable component), 25 parts by mass of EO-modified isocyanuric acid di- and triacrylate (trade name: M-315, manufactured by Toagosei Co., Ltd., polymerizable component), 2 parts by mass of dilauroyl peroxide (trade name: Perloyl L, manufactured by NOF Corporation, polymerization initiator), 2 parts by mass of benzoyl peroxide (trade name: Niper BW, manufactured by NOF Corporation), An adhesive composition was prepared by adding PMA (propylene glycol monomethyl ether) as a solvent to 1.0 part by mass of imidazole silane (trade name: IM-1000, manufactured by ENEOS Corporation, polymerization initiator), 3 parts by mass of conductive particles (Micropearl AU, manufactured by Sekisui Chemical Co., Ltd., Au-Ni plated resin particles, average particle size 4 μm), and 3 parts by mass of insulating filler (A) (trade name: YA050C, manufactured by Admatechs Corporation, average particle size 50 nm, spherical silica), and mixing them uniformly.

[0056] - Fabrication of anisotropic conductive film - A PET film (50 μm thick, 250 mm square) was prepared as a release substrate. The adhesive composition was uniformly applied to this release substrate so that the thickness of the anisotropic conductive film (adhesive layer) after drying would be 25 μm. The resulting film was then dried in an oven at 80°C to form an adhesive layer on the release substrate.

[0057] [Example 2] An adhesive composition was prepared and an anisotropic conductive film was produced in the same manner as in Example 1, except that the amount of silane coupling agent was 1.5 parts by mass and the insulating filler (A) was changed to insulating filler (B) (product name: YA100C, manufactured by Admatechs Co., Ltd., average particle size 100 nm, spherical silica).

[0058] [Example 3] An adhesive composition was prepared and an anisotropic conductive film was produced in the same manner as in Example 1, except that the amount of silane coupling agent was 1.5 parts by mass and the insulating filler (A) was changed to insulating filler (C) (product name: MX100W, manufactured by Nippon Shokubai Co., Ltd., average particle size 150 nm, spherical silica).

[0059] [Comparative Example 1] An adhesive composition was prepared and an anisotropic conductive film was produced in the same manner as in Example 1, except that the insulating filler (A) and the silane coupling agent were not blended.

[0060] Comparative Example 2 An adhesive composition was prepared and an anisotropic conductive film was produced in the same manner as in Example 1, except that no silane coupling agent was added and the amount of insulating filler (A) added was changed to 1 part by mass.

[0061] Comparative Example 3 An adhesive composition was prepared and an anisotropic conductive film was produced in the same manner as in Example 1, except that no silane coupling agent was added and the amount of insulating filler (A) added was changed to 10 parts by mass.

[0062] Comparative Example 4 An adhesive composition was prepared and an anisotropic conductive film was produced in the same manner as in Example 1, except that the amount of silane coupling agent was 1.5 parts by mass and the insulating filler (A) was changed to insulating filler (E) (trade name: R820, manufactured by Ishihara Sangyo Kaisha, Ltd., titanium oxide, irregular shape).

[0063] Comparative Example 5 An adhesive composition was prepared and an anisotropic conductive film was produced in the same manner as in Example 1, except that the amount of silane coupling agent was changed to 1.5 parts by mass and the insulating filler (A) was changed to insulating filler (D) (trade name: X-52-7030, manufactured by Shin-Etsu Silicones Co., Ltd., average particle size 800 nm, spherical silica).

[0064] Comparative Example 6 An adhesive composition was prepared and an anisotropic conductive film was produced in the same manner as in Example 1, except that the insulating filler (A) was not blended.

[0065] Comparative Example 7 An adhesive composition was prepared and an anisotropic conductive film was produced in the same manner as in Example 1, except that no silane coupling agent was added and the amount of conductive particles added was changed to 6 parts by mass.

[0066] The test and evaluation methods are explained below.

[0067] <Conductive particle aggregation and number of aggregates> The anisotropic conductive films produced in the examples and comparative examples were visually observed on one A4 sheet at 200x magnification using an optical microscope to check for the presence or absence of aggregates (15 μm or more). Furthermore, for films where aggregates were confirmed, the number of aggregates was counted. The number of aggregates was converted into an A4 size area.

[0068] - Fabrication of connection structure - The exposed surface of the adhesive layer was attached to an ITO glass substrate and temporarily fixed by pressure bonding at 45°C, 1 MPa, and 2 seconds. The release substrate was then peeled off, and a flexible printed circuit board (25 μm polyimide layer, 18 μm copper foil, Au plating, L / S = 200 μm / 200 μm) was connected and bonded to the adhesive layer. The FPC and glass substrate were thermocompression bonded via the adhesive layer, and all of the opposing conductive parts of the FPC and glass substrate were bonded with the cured adhesive layer, resulting in a connected structure. Thermocompression bonding conditions were 150°C, 3 MPa, and 10 seconds.

[0069] <Evaluation of conduction resistance> The electrical resistance of the resulting connection structure was measured, and a resistance of 0.5Ω or less was indicated as ◯, and a resistance of more than 0.5Ω was indicated as Δ.

[0070] <Evaluation of adhesive strength> The resulting connection structure was subjected to a 90-degree peel test to measure its adhesive strength. Specifically, the FPC and the cured product were cut to a length of 1.0 cm, and the 1.0 cm FPC was gripped with a gripper and pulled vertically at room temperature (25°C) at a speed of 50 mm / min until the FPC peeled off from the glass substrate. The load (N / cm) was measured. A Tensilon testing machine (STA-1150, manufactured by Orientec Co., Ltd.) was used for the measurement.

[0071] The evaluation results of the examples and comparative examples are shown in Table 1.

[0072] [Table 1]

[0073] According to Comparative Examples 1 and 6, it was confirmed that the addition of a coupling agent improves adhesive strength, but increases the number of agglomerates of conductive particles.

[0074] It was confirmed that the adhesive compositions of Examples 1 to 3, which contain insulating filler with a particle size of 5% or less of the conductive particles in a proportion of 85% by mass to 200% by mass relative to the amount of conductive particles, can suppress the aggregation of conductive particles. By suppressing the aggregation of conductive particles, it is possible to prevent the occurrence of short circuits, etc. Furthermore, in Examples 1 to 3, no increase in resistance was observed even with the addition of insulating filler. Furthermore, it was confirmed that high adhesive strength was obtained even under low-temperature, short-time compression bonding conditions in Example 1. Furthermore, in Comparative Example 4, which contains non-spherical insulating filler, the insulating filler was contained in a proportion of 85% by mass to 200% by mass relative to the amount of conductive particles, but no effect of suppressing the aggregation of conductive particles was observed.

Claims

1. a binder composition containing a polymerizable component and a film-forming component; a polymerization initiator; Conductive particles having a particle diameter of 1 μm or more and 10 μm or less; an insulating filler having a particle size of 5% or less of the conductive particles; a silane coupling agent; and no photocuring initiator, the blending amount of the insulating filler is 85% by mass or more and 200% by mass or less of the conductive particles, the polymerization initiator is an organic peroxide, and the one-minute half-life temperature of the organic peroxide is 80°C or more and 130°C or less.

2. The adhesive composition according to claim 1 , wherein the insulating filler is spherical.

3. An anisotropic conductive film comprising the adhesive composition according to claim 1 or 2.

4. A connection structure in which a first electronic component and a second electronic component are connected by the anisotropic conductive film according to claim 3 .

5. A method for manufacturing a connection structure, comprising a step of pressure-bonding a first electronic component and a second electronic component with the anisotropic conductive film according to claim 3 interposed therebetween.

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