JP2024033072A - Anisotropic conductive film, connection structure and manufacturing method of connection structure - Google Patents

Abstract

To provide an anisotropic conductive film which suppresses increase in a conductive resistance value, prevents a gap between the anisotropic conductive film and a terminal, and can keep connection reliability for a long period, in the case of high pressure mounting, and to provide a connection structure, and a manufacturing method of the connection structure.SOLUTION: An anisotropic conductive film contains (A) an epoxy resin, (B) an epoxy resin curing agent having a melting point of 60°C or higher, (C) a (meth)acrylate monomer, and (D) a radical polymerization initiator, and has a glass transition temperature of 85°C or higher and minimum melting viscosity of 20,000 Pa s or more and 90,000 Pa s or less.SELECTED DRAWING: None

Description

The present invention relates to an anisotropic conductive film, a connected structure, and a method for manufacturing a connected structure.

2. Description of the Related Art Anisotropic conductive films (ACF) are widely used as a means for bonding electronic components, circuit boards, and the like. As this anisotropic conductive film, an anisotropic conductive film containing an epoxy resin is used from the viewpoint of adhesiveness and connection reliability.

Furthermore, in order to reduce thermal stress on the terminal portions of rigid substrates, it is required to lower the thermocompression bonding temperature of anisotropic conductive films. Furthermore, from the viewpoint of improving productivity, it is desired to shorten the crimping time. In response to such demands, an anisotropic conductive film using a radically polymerizable (meth)acrylic compound that can be cured at low temperatures and in a short time in place of epoxy resin has also been proposed.

Furthermore, since anisotropic conductive films using radically polymerizable (meth)acrylic compounds have room for improvement in adhesion, anisotropic conductive films that use a combination of epoxy resin and radically polymerizable (meth)acrylic compounds are also available. It has been proposed (for example, see Patent Documents 1 to 4).

In recent years, in order to stabilize the conduction resistance value of connected structures bonded with anisotropic conductive films, it has become desirable to mount them at a high pressure of about 6 MPa, which was conventionally crimped at about 3 to 4 MPa. There is. However, when high-voltage mounting is performed using the conventionally used anisotropic conductive film, the amount of film pushed into the connection part is large, and the stress that the pushed film recovers due to elasticity after mounting is large, so the circuit board There were problems such as voids (peeling) occurring around the sides of the terminals, adhesive strength decreasing after environmental testing, and voids widening to increase conduction resistance.

Japanese Patent Application Publication No. 2006-127776 JP2007-224228A Japanese Patent Application Publication No. 2021-93357 JP2021-88645A

The present invention has been made in view of the above, and even when high-voltage mounting is performed, the increase in conduction resistance is suppressed, and the connection is reliable without creating a gap between the anisotropic conductive film and the terminal. An object of the present invention is to provide an anisotropic conductive film, a connected structure, and a method for manufacturing the connected structure that can maintain properties for a long period of time.

As a result of intensive studies on the above-mentioned problems, the present inventors discovered that the above-mentioned problems can be solved by an anisotropic conductive film, a connected structure, and a method for manufacturing a connected structure having the following configurations, and have completed the present invention. Ta.

That is, the present invention includes the following contents.
[1] (A) Epoxy resin;
(B) an epoxy resin curing agent with a melting point of 60°C or higher;
(C) (meth)acrylate monomer;
(D) a radical polymerization initiator;
including;
Glass transition temperature is 85℃ or higher,
An anisotropic conductive film having a minimum melt viscosity of 20,000 Pa·s or more and 90,000 Pa·s or less.
[2] (E) Contains a film-forming resin with a glass transition temperature of 100°C or higher,
The anisotropic conductive film according to claim 1, wherein the blending ratio of the film-forming resin (E) having a glass transition temperature of 100° C. or higher in the anisotropic conductive film is 20 to 60% by mass.
[3] Contains (C') (meth)acrylate oligomer,
The anisotropic conductive film according to claim 1, wherein the mass mixing ratio of (C) (meth)acrylate monomer and (C') (meth)acrylate oligomer is 10:90 to 70:30.
[4] (F) Contains filler,
The anisotropic conductive film according to claim 1, wherein the blending ratio of the filler (F) in the anisotropic conductive film is 1 to 15% by mass.
[5] The anisotropic conductive film according to claim 2, wherein (E) the film-forming resin having a glass transition temperature of 100° C. or higher is a phenoxy resin.
[6] (G) The anisotropic conductive film according to claim 1, comprising conductive particles.
[7] A connected structure in which a first electronic component and a second electronic component are connected by the anisotropic conductive film according to claim 1.
[8] A method for manufacturing a connected structure, comprising the step of crimping a first electronic component and a second electronic component with the anisotropic conductive film according to claim 1 interposed therebetween.

According to the present invention, even when performing high-voltage mounting, it is possible to obtain an anisotropic conductive film that has excellent conduction resistance and has high connection reliability over a long period of time without creating gaps due to pressing.

FIG. 1 is a schematic cross-sectional view when a connected structure is manufactured using an anisotropic conductive film.

Embodiments of the present invention will be described in detail below. The present invention is not limited to the following description, and each component can be modified as appropriate without departing from the gist of the present invention.

[Anisotropic conductive film]
The anisotropic conductive film of the present invention comprises (A) an epoxy resin, (B) an epoxy resin curing agent having a melting point of 60°C or higher, (C) a (meth)acrylate monomer, and (D) a radical polymerization initiator. , and has a glass transition temperature of 85° C. or higher and a minimum melt viscosity of 20,000 Pa·s or more and 90,000 Pa·s or less.

(A) Epoxy resin Examples of epoxy resins include bisphenol A epoxy resin, bisphenol F epoxy resin, phenol novolac epoxy resin, naphthalene epoxy resin, biphenyl epoxy resin, trisphenol epoxy resin, naphthol epoxy resin, etc. can be used. When imparting good low-temperature and rapid curing properties to the anisotropic conductive film, it is preferable to use an alicyclic epoxy resin having two or more glycydicyl groups in one molecule as the epoxy resin. The epoxy resin used may be liquid or solid, and two or more types may be used in combination. Preferred examples of the epoxy resin include diglycidylhexahydrobisphenol A, 3,4-epoxycyclohexenylmethyl-3',4'-epoxycyclohexenecarboxylate, and diepoxybicyclohexyl. Among these, diglycidylhexahydrobisphenol A, particularly diepoxybicyclocyclohexyl, is preferred from the viewpoint of ensuring the optical transparency of the cured product and having excellent rapid curing properties.

The content of the epoxy resin in the anisotropic conductive film is preferably 2% by mass or more, more preferably 4% by mass or more, and particularly preferably 6% by mass or more, based on the total amount of resin components. Moreover, the content of the epoxy resin in the anisotropic conductive film is preferably 35% by mass or less, more preferably 30% by mass or less, and particularly preferably 20% by mass or less, based on the total amount of the resin component and the curing agent component. By setting the content of the epoxy resin within the above range, high adhesive strength and pressure bonding can be achieved at low temperatures and in a short time.

(B) Epoxy resin curing agent with a melting point of 60°C or higher The anisotropic conductive film of the present invention contains an epoxy resin curing agent with a melting point of 60°C or higher. By using an epoxy resin curing agent with a melting point of 60° C. or higher, the storage stability of the anisotropic conductive film is improved. The epoxy resin curing agent having a melting point of 60° C. or higher is preferably a latent curing agent that does not react at room temperature, and the reaction proceeds and completes in a short time at the pressure bonding temperature during mounting.

Epoxy resin curing agents with a melting point of 60°C or higher are not particularly limited as long as they have a melting point of 60°C or higher and function as a curing agent for epoxy resins, but include amine-based, imidazole-based, hydrazide-based, and trifluoride-based curing agents. Examples include boron-amine complexes, sulfonium salts, amine imides, dicyandiamide salts, and modified products thereof. As the epoxy resin curing agent having a melting point of 60° C. or higher, diaminodiphenylmethane, metaphenylenediamine, diaminodiphenylsulfone, etc. are preferable. Epoxy resin curing agents with a melting point of 60°C or higher may be used in combination of two or more types, but the combination with an epoxy resin curing agent with a melting point of less than 60°C may affect the storage stability of the anisotropic conductive film. Not desirable from that point of view.

The content of the epoxy resin curing agent having a melting point of 60° C. or higher in the anisotropic conductive film is preferably 0.5% by mass or more, more preferably 0.8% by mass or more, and particularly preferably 1% by mass or more. The content of the epoxy resin curing agent having a melting point of 60° C. or higher in the anisotropic conductive film is preferably 5% by mass or less, more preferably 4% by mass or less, and particularly preferably 3.5% by mass or less. By setting the content of the epoxy resin curing agent having a melting point of 60°C or higher within the above range, high adhesiveness can be exhibited even at low temperatures and for a short time.

(C) (meth)acrylate monomer The anisotropic conductive film of the present invention contains a (meth)acrylate monomer. In this specification, the term (meth)acrylate monomer is used to include acrylate monomers and methacrylate monomers. By containing the (meth)acrylate monomer in the anisotropic conductive film, pressure bonding can be performed at low temperatures and in a short time. The (meth)acrylate monomer preferably has two functional groups. Moreover, from the viewpoint of adjusting adhesive strength, the anisotropic conductive film of the present invention preferably contains a (meth)acrylate oligomer in addition to a (meth)acrylate monomer.

Examples of (meth)acrylate monomers and (meth)acrylate oligomers include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, isooctyl ( meth)acrylate, lauryl(meth)acrylate, stearyl(meth)acrylate, cyclohexyl(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, phosphate ester type(meth)acrylate, bisphenoxyethanol full Orange (meth)acrylate, 2-(meth)acryloyloxyethylsuccinic acid, isobornyl (meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, Tetrahydrofurfuryl (meth)acrylate, o-phthalic acid diglycidyl ether (meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethanetetra(meth)acrylate, 2-hydroxy-1,3-di(meth)acrylate Acryloxypropane, 2,2-bis[4-((meth)acryloxymethoxy)phenyl]propane, 2,2-bis[4-((meth)acryloxypolyethoxy)phenyl]propane, dicyclopentenyl(meth) ) acrylate, tricyclodecanyl (meth)acrylate, tris((meth)acryloyloxyethyl)isocyanurate, and urethane (meth)acrylate.

The total content of the (meth)acrylate monomer and (meth)acrylate oligomer in the anisotropic conductive film is preferably 5% by mass or more, more preferably 10% by mass or more, and particularly preferably 15% by mass or more. The total content of the (meth)acrylate monomer and (meth)acrylate oligomer in the anisotropic conductive film is preferably 60% by mass or less, more preferably 50% by mass or less, and particularly preferably 40% by mass or less. By setting the total content of the (meth)acrylate monomer and (meth)acrylate oligomer within the above range, high adhesiveness can be exhibited even at low temperatures and for a short time.

When (meth)acrylate monomer and (meth)acrylate oligomer are used together, the blending ratio (mass) is preferably 10:90 to 70:30.

(D) Radical polymerization initiator The anisotropic conductive film of the present invention contains a radical polymerization initiator. The radical polymerization initiator is not particularly limited as long as it can generate free radicals at the thermocompression bonding temperature during packaging and advance the polymerization reaction of (meth)acrylate monomers and (meth)acrylate oligomers, and can be selected as appropriate. can.

Examples of the radical polymerization initiator include peroxide compounds and azo compounds. As the peroxide compound, organic peroxides are suitable, and examples thereof include lauroyl peroxide, butyl peroxide, benzyl peroxide, dilauroyl peroxide, dibutyl peroxide, peroxydicarbonate, and benzoyl peroxide. These may be used alone or in combination of two or more.

The content of the radical polymerization initiator in the anisotropic conductive film is preferably 1% by mass or more, more preferably 3% by mass or more, and particularly preferably 5% by mass or more. The content of the radical polymerization initiator in the anisotropic conductive film is preferably 20% by mass or less, more preferably 18% by mass or less, and particularly preferably 15% by mass or less. By setting the content of the radical polymerization initiator within the above range, high adhesiveness can be exhibited even at low temperatures and for a short time.

(E) Film-forming resin The anisotropic conductive film of the present invention contains a film-forming resin. Examples of film-forming resins include phenoxy resins, unsaturated polyester resins, saturated polyester resins, urethane resins, butadiene resins, polyimide resins, polyamide resins, and polyolefin resins. These may be used alone or in combination of two or more. As the film-forming resin, those having a glass transition temperature of 100°C or higher are preferred, and phenoxy resins having a glass transition temperature of 100°C or higher are particularly preferred. By including a film-forming resin with a glass transition temperature of 100°C or higher, it becomes easy to adjust the glass transition temperature of the anisotropic conductive film to 85°C or higher. It becomes possible to suppress the rise in

From the viewpoint of film-forming properties, the weight average molecular weight (Mw) of the film-forming resin in terms of polystyrene is preferably 10,000 or more, more preferably 15,000 or more, and particularly preferably 20,000 or more. The upper limit of the weight average molecular weight (Mw) is preferably 80,000 or less, more preferably 70,000 or less, and particularly preferably 60,000 or less. The polystyrene equivalent Mn of the film-forming resin can be measured by gel permeation chromatography (GPC) and calculated using a standard polystyrene calibration curve.

The content of the film-forming resin in the anisotropic conductive film is preferably 20% by mass or more, more preferably 25% by mass or more, and particularly preferably 30% by mass or more. The content of the film-forming resin in the anisotropic conductive film is preferably 60% by mass or less, more preferably 55% by mass or less, and particularly preferably 50% by mass or less.

(F) Filler The anisotropic conductive film of the present invention preferably contains a filler. By containing the filler, it becomes easy to adjust the minimum melt viscosity, and it is possible to prevent the generation of voids during high-pressure mounting.

Examples of 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, calcium carbonate, magnesium carbonate, and carbonate. Examples include inorganic carbonates such as zinc 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. Silica is preferred as the filler. The size of the filler is preferably 10 nm to 2 μm.

The content of the filler in the anisotropic conductive film is preferably 0.5% by mass or more, more preferably 1% by mass or more, and particularly preferably 2% by mass or more. The content of filler in the anisotropic conductive film is preferably 30% by mass or less, more preferably 20% by mass or less, particularly preferably 15% by mass or less.

(G) Conductive particles The anisotropic conductive film of the present invention contains conductive particles. As the conductive particles, known conductive particles used in anisotropic conductive films may be used. 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; metal oxides, carbon, graphite, glass, Examples include coated particles in which the surfaces of particles of ceramic, resin, etc. are coated with metal. When using metal-coated resin particles in which the surface of the resin particles is coated with metal, examples of the material for the resin particles include epoxy resin, phenol resin, acrylic resin, acrylonitrile styrene (AS) resin, benzoguanamine resin, and divinylbenzene resin. , styrene resin, etc. In addition, conductive particles may be coated with an insulating thin film on the surface of the conductive particles or coated with insulating particles in order to avoid the risk of short circuits between terminals, as long as they do not interfere with the conductivity after connection. It may also be one that has been subjected to insulation treatment, such as one that is attached to the surface. These conductive particles may be used alone or in combination of two or more.

The average particle diameter of the conductive particles is preferably 1 μm or more, more preferably 2 μm or more. Further, the average particle diameter of the conductive particles is preferably 10 μm or less, more preferably 7 μm or less. The average particle diameter of the conductive particles may be determined by, for example, observing with a scanning electron microscope (SEM), measuring the particle diameters of a plurality of conductive particles (n≧10), and calculating the average value. Alternatively, it may be a measured value (N=1000 or more) measured using an image-type particle size distribution analyzer (for example, FPIA-3000 (Malvern)).

The content of conductive particles in the anisotropic conductive film is not particularly limited and may be appropriately determined depending on the purpose, but is preferably 1% by mass or more, more preferably 2% by mass or more. The upper limit of the content of conductive particles is preferably 20% by mass or less, more preferably 10% by mass or less from the viewpoint of obtaining a predetermined anisotropic conductivity.

(H) Other components The anisotropic conductive film of the present invention may contain a silane coupling agent. By containing a silane coupling agent, interfacial adhesion with inorganic materials can be improved. Examples of the silane coupling agent include those having a vinyl group, an acrylic group, a methacryl group, an epoxy group, a mercapto group, an amino group, an isocyanate group, a ureido group, and an imidazole group. The silane coupling agents may be used alone or in combination of two or more.

In the anisotropic conductive film 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.

The anisotropic conductive film of the present invention may further contain other components as necessary. Such components include, for example, known additives used in the manufacture of adhesive compositions, such as surface modifiers, flame retardants, colorants, and the like.

(I) Physical properties of anisotropic conductive film The anisotropic conductive film of the present invention has a glass transition temperature of 85°C or higher. When the glass transition temperature of the anisotropic conductive film is 85° C. or higher, it is possible to suppress a decrease in adhesive strength and an increase in conduction resistance value in a reliability test. In order to make the glass transition temperature of the anisotropic conductive film 85°C or higher, it is preferable to use a film-forming resin with a glass transition temperature of 100°C or higher.

The anisotropic conductive film of the present invention has a minimum melt viscosity of 20,000 Pa·s or more and 90,000 Pa·s or less. By setting the minimum melt viscosity of the anisotropic conductive film to 20,000 Pa·s or more and 90,000 Pa·s or less, it is possible to prevent the generation of voids during high-pressure mounting. In order to set the minimum melt viscosity of the anisotropic conductive film to 20,000 Pa·s or more and 90,000 Pa·s or less, it is preferable to mix a filler. The minimum melt viscosity of the anisotropic conductive film is particularly preferably 30,000 Pa·s or more and 80,000 Pa·s or less.

[Configuration of anisotropic conductive film]
The anisotropic conductive film of the present invention may consist of a single layer or multiple layers. When the anisotropic conductive film is composed of multiple layers, the anisotropic conductive film may include a laminated film consisting of the anisotropic conductive film layer according to the present invention and an insulating layer, or a laminated film comprising the anisotropic conductive film layer according to the present invention, an insulating layer, and an insulating layer. A laminated film consisting of two anisotropic conductive film layers is exemplified. The second anisotropic conductive film layer may be an anisotropic conductive film according to the present invention, or may be an anisotropic conductive film different from the present invention.

The anisotropic conductive film can be produced, for example, by mixing the constituent materials of the anisotropic conductive film of the present invention with an organic solvent as necessary to form a mixed composition, and then applying the composition onto a release substrate and drying it. It can be manufactured by forming an anisotropic conductive film layer. The mixed composition may be applied using a coating device such as a bar coater. A known anisotropic conductive film coating method such as a doctor blade method can be used. When manufacturing an anisotropic conductive film consisting of multiple layers, the above coating and drying steps may be repeated multiple times. Alternatively, they may be manufactured individually and laminated together using laminate or the like.

The release base material 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 a desired timing. Examples of materials for the release base material 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). may be used. The release base material may also be a base material having a release layer on the surface to be bonded to the anisotropic conductive film, and the release layer may include a release agent such as a silicone resin or a polyolefin resin.

The thickness of the release base material 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 base material is not particularly limited, but is preferably 8 μm or more from the viewpoint of ease of handling during production and slitting of the anisotropic conductive film.

The thickness of the anisotropic conductive film of the present invention is not particularly limited and may be appropriately determined depending on the purpose, but is preferably 1 μm or more, more preferably 2 μm or more, and still more preferably 3 μm or more. The upper limit of the thickness of the anisotropic conductive film is not particularly limited, but is preferably 50 μm or less, more preferably 40 μm or less, even more preferably 30 μm or less, even more preferably 20 μm or less, particularly preferably 10 μm or less. If multiple layers are laminated, the total thickness excludes the insulating layer.

The anisotropic conductive film may be slit to have a predetermined width. During slitting, a cover film may be provided on the exposed surface of the adhesive layer in order to prevent the adhesive layer from being contaminated by cutting debris or the like. The thickness in this case may be appropriately selected depending on the purpose. As the cover film, a known film used for slitting an anisotropic conductive film may be used. The cover film may be provided separately from the release base material in order to prevent contamination during use, in addition to the manufacturing process of slits, etc., and as a product used for connection. In this case, the cover film preferably has releasability and preferably has the same thickness as or thinner than the release base material.

The anisotropic conductive film of the present invention suppresses an increase in conduction resistance even when mounted under high pressure, and does not create a gap between the anisotropic conductive film and the terminal of the electronic component to be connected. It becomes possible to maintain connection reliability for a long period of time.

[Connection structure]
Using the anisotropic conductive film of the present invention, a connected structure in which electronic components are bonded together can be manufactured. The present invention includes a connected structure in which a first electronic component and a second electronic component are connected by the anisotropic conductive film of the present invention.

The first electronic component may be, for example, a general PWB, such as a rigid substrate, a glass substrate, a ceramic substrate, a plastic substrate, an FPC, etc., and the second electronic component may be an FPC, an IC chip, Examples include semiconductor elements other than IC chips. There are no particular restrictions on the electronic components, and there are no particular restrictions on the uses of the connection structure. For example, it may be used for a portable information terminal or for electrical mounting on a vehicle. In the present invention, various connection structures such as FOB, FOG, FOP, FOF, COG, and COP can be manufactured, for example.

[Method for manufacturing connected structure]
The method for manufacturing a connected structure of the present invention is not particularly limited as long as it can manufacture a connected structure in which a first electronic component and a second electronic component are connected by the anisotropic conductive film of the present invention. An example of the method for manufacturing the connected structure of the present invention will be shown below.

In one embodiment, the method for manufacturing a bonded structure of the present invention includes the step of crimping a first electronic component and a second electronic component with the anisotropic conductive film of the present invention interposed therebetween.

First, a first electronic component is placed on a stage, the anisotropic conductive film of the present invention is provided thereon, and then a second electronic component is placed thereon. Here, after providing the anisotropic conductive film of the present invention on the first electronic component placed on the stage, the electrodes of the first electronic component and the second electronic component are aligned so that they face each other. Then, temporary crimping is performed using a crimping tool from the second electronic component side. The temperature, pressure, and time during temporary pressure bonding may be determined as appropriate 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. It is preferable to carry out preliminary crimping before carrying out the main crimping described later, since it is possible to more accurately align and connect the electronic components (conducting portions of the respective components) to each other. By performing temporary crimping, it can be expected to suppress positional displacement during main crimping, which is performed by pressing with higher pressure.

After the preliminary crimping, the main crimping is performed from the second electronic component side using a crimping tool. The temperature, pressure, and time during the main pressure bonding may be any known conditions used when bonding electronic components using an anisotropic conductive film, and may be determined as appropriate depending on the specific design. For example, even if the pressure bonding is performed at a low temperature (e.g., 160°C or less), for a short time (e.g., 10 seconds or less), and at a high pressure (e.g., 6 MPa), the first electronic component and the second electronic component can be bonded well. It is possible to glue.

Note that a cushioning material (for example, a buffer sheet) may be provided between the second electronic component and the crimping tool, regardless of whether the crimping is temporary crimping or actual crimping. The cushioning material, including whether or not to use it, may be adjusted and determined as appropriate depending on the combination of electronic components.

The anisotropic conductive film of the present invention has a high trapping efficiency of conductive particles present between the electrodes of the first electronic component and the electrodes of the second electronic component during pressure bonding. Even when the amount of conductive particles incorporated therein is reduced, it is possible to keep the electrical resistance low.

Hereinafter, the present invention will be specifically explained by showing 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.

[Materials used]
-Epoxy resin-
Epoxy resin (EP828, manufactured by Japan Epoxy Resin Co., Ltd.)
-Epoxy resin curing agent with a melting point of 60℃ or higher-
Diaminodiphenylmethane (DDM) manufactured by Tokyo Chemical Industry Co., Ltd.
- Epoxy resin curing agent with a melting point of less than 60°C -
2-ethyl-4-methyl-imidazole (2E4MZ, manufactured by Shikoku Kasei Co., Ltd.)
-(meth)acrylate monomer-
Polyethylene glycol diacrylate (A-200, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.)
-(meth)acrylate oligomer-
Urethane acrylate (U-2PPA, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.)
-Radical polymerization initiator-
Dilauroyl peroxide (Perloyl (registered trademark) L, manufactured by NOF Corporation)
-Film-forming resin-
Phenoxy resin (FX-293, manufactured by Nippon Steel Chemical & Materials Co., Ltd., Tg: 158°C)
Phenoxy resin (FX-316, manufactured by Nippon Steel Chemical & Materials Co., Ltd., Tg: 68°C)
-Filler-
Silica (Aerosil (registered trademark) R202, manufactured by Nippon Aerosil Co., Ltd.)
-Conductive particles-
Nickel particles (Micropearl Au, manufactured by Sekisui Chemical Co., Ltd., average particle size 3 μm)

[Example 1]
-Preparation of adhesive composition-
30 parts by mass of (meth)acrylate oligomer, 50 parts by mass of (meth)acrylate monomer, 20 parts of epoxy resin, 3 parts by mass of epoxy resin curing agent with a melting point of 60°C or higher, 12 parts by mass of radical polymerization initiator, phenoxy resin (FX- 293) 100 parts by mass, 20 parts by mass of filler, and 5 parts by mass of conductive particles were added to 150 parts of solvent and mixed uniformly to obtain an adhesive composition.

-Preparation of anisotropic conductive film-
A PET film (thickness: 50 μm) was prepared as a release base material. The adhesive composition was uniformly applied onto this release base material so that the thickness of the adhesive layer after drying was 35 μm. Thereafter, it was dried at 60° C. for 5 minutes to form an adhesive layer on the release base material to obtain an anisotropic conductive film.

- Fabrication of connected structure -
A connected structure was produced using a glass substrate, FPC, and the above-mentioned anisotropic conductive film. After the anisotropic conductive film was slit to a predetermined width and pasted on a glass substrate, and the FPC was temporarily fixed on the pasted anisotropic conductive film, it was covered with tetrafluoroethylene (average thickness 50 μm) as a cushioning material. Pressure bonding was performed using a heated heat tool at a temperature of 160° C. and a pressure of 6 MPa for 5 seconds to complete a connected structure.

-Evaluation of continuity resistance-
Regarding the connection state between the FPC and the glass substrate, the conduction resistance (Ω) at the initial stage and after the environmental test was measured using a digital multimeter. The environmental test was conducted under the conditions of temperature 85° C., humidity 85%, and time 500 hours.
Regarding the conduction resistance value, less than 5Ω was evaluated as “○”, 5Ω or more and less than 10Ω was evaluated as “△”, and 10Ω or more was evaluated as “x”. Practically speaking, it is sufficient if it is "△" or more, and preferably "○".

-Evaluation of adhesive strength-
The adhesive strength of the connected structure was measured by a 90 degree peel test. Specifically, the FPC and the cured product were cut to a length of 1.0 cm, the 1.0 cm long FPC was grabbed with a grip, and the FPC was cut vertically at a speed of 50 mm/min at room temperature (25°C). The load (N/cm) when peeled off from the glass substrate was measured. Note that a Tensilon tester (manufactured by Orientec Co., Ltd.: STA-1150) was used for the measurement. Furthermore, the adhesive strength of the connected structure after the environmental test (temperature: 85° C., humidity: 85%, time: 500 hours) was similarly evaluated.
The adhesive strength was evaluated as "○" if it was 10 N/cm or more, "△" if it was 5 N/cm or more and less than 10 N/cm, and "x" if it was less than 5 N/cm. Practically speaking, it is sufficient if it is "△" or more, and preferably "○".

-Peeling evaluation-
The connected structure was visually evaluated using an electron microscope for the presence or absence of peeling between the anisotropic conductive film and the terminal of the FPC. Furthermore, the connected structure after the environmental test (temperature: 85° C., humidity: 85%, time: 500 hours) was similarly evaluated for peeling.
FIG. 1 is a schematic cross-sectional view of a connected structure using an anisotropic conductive film. As shown in FIG. 1, the connected structure is one in which an FPC 10 and a glass substrate 20 are connected by an anisotropic conductive film 30, and the terminals of the glass substrate 20 (not shown) and the terminals 11 of the FPC 10 are connected to conductive particles 31. electrically connected. 1(a) shows a state in which the terminal 11 and the anisotropic conductive film 30 are in close contact with each other without any gaps, and FIG. , FIG. 1(c) was evaluated as "x" in a state where the void 40 was generated to the side and below the terminal 11. Practically speaking, it is sufficient if it is "△" or more, and preferably "○".

-Evaluation of glass transition point-
The glass transition point of the anisotropic conductive film was measured using a dynamic viscoelasticity measuring device Rheobabloon manufactured by A&D Co., Ltd. The glass transition point was measured after the anisotropic conductive film was placed in an oven at 200° C. for 3 hours and completely cured.
Measurement temperature: -10°C to 200°C, heating rate: 3°C/min, frequency: 11Hz. Those with a glass transition point of 85°C or higher were evaluated as "○", and those with a glass transition point of less than 85°C were evaluated as "x".

-Minimum melt viscosity-
A sheet was prepared by stacking anisotropic conductive films to a thickness of 300 μm, and the minimum melt viscosity was measured using a melt viscometer (manufactured by Thermo Fisher Scientific).
Measurement was performed at a heating rate of 10°C/min, a frequency of 1Hz, a pressing force of 1N, and a measurement temperature range of 30 to 180°C.
If the minimum melt viscosity is 30,000 Pa・s or more and 80,000 Pa・s or less, “○”, 20,000 Pa・s or more and less than 30,000 Pa・s, and more than 80,000 Pa・s and 90,000 Pa・s or less “△” ”, less than 20,000 Pa·s, and larger than 90,000 Pa·s were evaluated as “×”. Practically speaking, it is sufficient if it is "△" or more, and preferably "○".

-Film life-
After being left at 55° C. for 24 hours, a bonded structure was prepared using the film, and the adhesive strength was evaluated. 10 N/cm or more was rated "○", 5 N/cm or more but less than 10 N/cm was rated "Δ", and less than 5 N/cm was rated "x".

Table 1 shows the formulation and evaluation results of the anisotropic conductive film.

[Example 2] to [Example 5]
An anisotropic conductive film was produced by changing the blending amounts of epoxy resin, acrylate monomer, acrylate oligomer, phenoxy resin, and filler to those shown in Table 1, and a connected structure was produced under the same conditions as in Example 1, We conducted an evaluation. The results are shown in Table 1.

[Comparative Examples 1 to 6]
The anisotropic conductive film was prepared by changing the formulations of epoxy resin, (meth)acrylate monomer, (meth)acrylate oligomer, filler, type and amount of phenoxy resin, and type of epoxy resin curing agent to those shown in Table 1. A connected structure was prepared under the same conditions as in Example 1, and evaluated. The results are shown in Table 1.

Contains an epoxy resin, an epoxy resin curing agent with a melting point of 60°C or higher, a (meth)acrylate monomer, and a radical polymerization initiator, and has a glass transition temperature of 85°C or higher and a minimum melt viscosity of 20,000 Pa·s or higher. The connected structures using the anisotropic conductive films of Examples 1 to 5, which have a strength of 90,000 Pa·s or less, did not peel off even after the initial and environmental tests, or had no practical problems, and had excellent adhesive strength and conductivity. It was confirmed that the resistance value was at a practical level even after the initial and environmental tests.

On the other hand, in Comparative Example 1 which did not contain an epoxy resin, peeling occurred after the environmental test and the adhesive strength decreased. Furthermore, in Comparative Example 2, which did not contain a (meth)acrylate monomer, peeling occurred from the beginning, and the adhesive strength and conduction resistance values were not at a practical level. Furthermore, in Comparative Example 3, in which the glass transition point was lower than 85° C., the conduction resistance increased and peeling increased after the environmental test. Note that phenoxy resins (YP-50, YD-019, manufactured by Nippon Steel Chemical & Materials Co., Ltd.) used as film-forming resins in Patent Document 4 (Japanese Unexamined Patent Publication No. 2021-88645) etc. also have a glass transition temperature. However, the glass transition temperature of the anisotropic conductive film using this film cannot be higher than 85°C, which is the same result as Comparative Example 3.

Furthermore, in Comparative Example 4 in which the minimum melt viscosity is less than 20,000 Pa·s, since the minimum melt viscosity is low, the amount of indentation of the film increases during mounting, causing peeling and increasing conduction resistance. Furthermore, in Comparative Example 5 in which the minimum melt viscosity is higher than 90,000 Pa·s, the minimum melt viscosity is too large, so that the conductive particles are not crushed during mounting, resulting in a high conduction resistance value. Furthermore, in Comparative Example 6 in which an epoxy resin curing agent with a melting point of less than 60° C. was used, it was confirmed that the film life was reduced due to the low stability of the epoxy resin curing agent.

Furthermore, Table 2 shows the results of evaluation of mounting structures prepared using the recipe of Example 1 and changing the mounting pressure to 3 Mpa and 8 Mpa. According to Table 2, it was confirmed that the anisotropic conductive film according to the present invention can be used when mounted at a pressure of 3 Mpa to 8 Mpa.

Claims (8)

(A) an epoxy resin;
(B) an epoxy resin curing agent with a melting point of 60°C or higher;
(C) (meth)acrylate monomer;
(D) a radical polymerization initiator;
including;
Glass transition temperature is 85℃ or higher,
An anisotropic conductive film having a minimum melt viscosity of 20,000 Pa·s or more and 90,000 Pa·s or less. (E) Contains a film-forming resin with a glass transition temperature of 100°C or higher,
The anisotropic conductive film according to claim 1, wherein the blending ratio of the film-forming resin (E) having a glass transition temperature of 100° C. or higher in the anisotropic conductive film is 20 to 60% by mass. (C') Contains (meth)acrylate oligomer,
The anisotropic conductive film according to claim 1, wherein the mass mixing ratio of (C) (meth)acrylate monomer and (C') (meth)acrylate oligomer is 10:90 to 70:30. (F) Contains a filler;
The anisotropic conductive film according to claim 1, wherein the blending ratio of the filler (F) in the anisotropic conductive film is 1 to 15% by mass. (E) The anisotropic conductive film according to claim 2, wherein the film-forming resin having a glass transition temperature of 100° C. or higher is a phenoxy resin. (G) The anisotropic conductive film according to claim 1, comprising conductive particles. A connected structure in which a first electronic component and a second electronic component are connected by the anisotropic conductive film according to claim 1. A method for manufacturing a connected structure, comprising the step of crimping a first electronic component and a second electronic component with the anisotropic conductive film according to claim 1 interposed therebetween.

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