Anisotropic conductive film, connection structure, and method for manufacturing connection structure

Abstract

Provided is an anisotropic conductive film having high adhesive strength. This anisotropic conductive film contains: a binder composition containing an epoxy compound and a film-forming component; an anionic latent curing agent that cures the epoxy compound; a silane coupling agent having two or more mercapto groups in one molecule, the main chain being an organic chain; and conductive particles.

Description

Technical Field

[0001] The present invention relates to an anisotropic conductive film, a connection structure, and a method for manufacturing the connection structure. Background Art

[0002] As a means for bonding electronic components and circuit boards, etc., anisotropic conductive films or film-like materials (adhesive films) such as anisotropic conductive paste (ACP: Anisotropic Conductive Paste) or anisotropic conductive film (ACF: Anisotropic Conductive Film) are widely used. For example, anisotropic conductive films are used in cases such as connecting the terminals of a flexible printed circuit board (FPC) and the terminals of a glass substrate of an FPD panel (so-called FOG), and bonding and electrically connecting various terminals to each other.

[0003] In the case of joining different base materials such as an FPC and a glass substrate, an anisotropic conductive film containing an epoxy compound having excellent adhesive strength and an anionic curing agent is used. In addition, an anisotropic conductive film in which an epoxy resin and a radically polymerizable (meth)acrylic acid compound are used in combination has been proposed in order to be able to bond at a low temperature while maintaining the adhesive strength (for example, refer to Patent Documents 1 to 3).

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2007-224228;

[0007] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2021-93357;

[0008] Patent Document 3: Japanese Unexamined Patent Application Publication No. 2021-88645. Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] In Patent Documents 1 to 3, by using an epoxy resin and a radically polymerizable (meth)acrylic acid compound in combination, it is possible to bond at a low temperature, but an anisotropic conductive film that can bond at a low temperature and has more excellent bonding strength is required.

[0011] The problem of the present invention is to provide an anisotropic conductive film that can bond at a low temperature and has excellent bonding strength.

[0012] Means for Solving the Problems

[0013] The present inventors conducted in-depth research on the above problems, and as a result, found that the above problems can be solved by an anisotropic conductive film having the following configuration, and thus completed the present invention.

[0014] That is, the present invention includes the following content.

[0015] [1] An anisotropic conductive film, comprising:

[0016] An adhesive composition containing an epoxy compound and a film-forming component;

[0017] An anionic latent curing agent for curing the epoxy compound;

[0018] A silane coupling agent having two or more mercapto groups in one molecule and an organic chain as the main chain; and

[0019] Conductive particles.

[0020] [2] The anisotropic conductive film according to claim 1, wherein the blending amount of the silane coupling agent is 0.5% by mass or more and 2.0% by mass or less.

[0021] [3] The anisotropic conductive film according to claim 1, wherein the blending amount of the silane coupling agent is 1.2% by mass or more and 1.8% by mass or less.

[0022] [4] A connection structure formed by connecting a first electronic component and a second electronic component through the anisotropic conductive film according to claim 1.

[0023] [5] A method for manufacturing a connection structure, comprising: a step of interposing the anisotropic conductive film according to claim 1 between a first electronic component and a second electronic component and performing crimping.

[0024] Advantages of the Invention

[0025] According to the present invention, an anisotropic conductive film can be provided, which can also be used for bonding requiring high bonding strength such as FOG mounting for mounting an FPC on a glass substrate, and has high adhesiveness even in the case of bonding at low temperature. Detailed Embodiments

[0026] Hereinafter, the present invention will be described in detail according to suitable embodiments of the present invention. The present invention is not limited by the following description, and each component can be appropriately changed without departing from the gist of the present invention.

[0027] [Anisotropic Conductive Film]

[0028] The anisotropic conductive film of the present invention is characterized by comprising: an adhesive composition containing an epoxy compound and a film-forming component; an anionic latent curing agent for curing the epoxy compound; a silane coupling agent having two or more mercapto groups in one molecule and an organic chain as the main chain; and conductive particles.

[0029] Hereinafter, each component will be described in detail.

[0030] <Adhesive Composition>

[0031] The anisotropic conductive film of the present invention contains: an adhesive composition containing an epoxy compound and a film-forming component.

[0032] (Epoxy Compound)

[0033] Examples of the epoxy compound used in the anisotropic conductive film of the present invention include: bisphenol A type liquid epoxy compound, bisphenol F type epoxy compound, and naphthalene type epoxy compound. The epoxy compound can be used alone or in combination of two or more.

[0034] The weight-average molecular weight of the epoxy compound used in the anisotropic conductive film of the present invention is preferably 150 to 6000, more preferably 200 to 2000.

[0035] In the anisotropic conductive film of the present invention, when the non-volatile components in the anisotropic conductive film are set to 100% by mass, the content of the epoxy compound is preferably 10% by mass or more, more preferably 15% by mass or more, further preferably 18% by mass or more, and even more preferably 20% by mass or more. There is no particular limitation on the upper limit of this content, and it is preferably 60% by mass or less, more preferably 55% by mass or less or 50% by mass or less.

[0036] (Film-Forming Component)

[0037] The film-forming component is not particularly limited as long as it has film-forming ability. The film-forming component can be appropriately selected according to the purpose, and examples thereof include: phenoxy resin, (meth)acrylate resin, epoxy resin (weight-average molecular weight of 10,000 or more), polyvinyl acetal resin, unsaturated polyester resin, saturated polyester resin, urethane resin, butadiene resin, polyimide resin, polyamide resin, polyolefin resin. The (meth)acrylate resin can preferably be a copolymer of a (meth)acrylate monomer and a compound having a reactive double bond copolymerizable with the (meth)acrylate monomer and a difunctional or polyfunctional monomer. The film-forming component can be used alone or in combination of two or more.

[0038] Among them, from the viewpoints of film-forming property, processability, and connection reliability, phenoxy resin and (meth)acrylate resin can be suitably used.

[0039] From the viewpoint of film-forming properties, the weight-average molecular weight (Mw) of the polystyrene conversion value of the film-forming component is preferably 10,000 or more, more preferably 15,000 or more, and further preferably 20,000 or more. There is no particular limitation on the upper limit of this Mw, and it can be preferably 80,000 or less, more preferably 70,000 or less, and 60,000 or less. It can be appropriately selected according to other blends or usage purposes. The Mw of the polystyrene conversion value of the film-forming component can be measured by gel permeation chromatography (GPC) method and calculated using the standard curve of standard polystyrene.

[0040] There is no particular limitation on the content of the film-forming component in the anisotropic conductive film, and it can be appropriately determined according to the purpose. When the non-volatile component in the anisotropic conductive film is set to 100% by mass, it is preferably 10% by mass or more, more preferably 15% by mass or more, further preferably 20% by mass or more, and still more preferably 25% by mass or more. There is no particular limitation on the upper limit of this content, and it is preferably 60% by mass or less, more preferably 50% by mass or less, and further preferably 40% by mass or less.

[0041] <Anionic latent curing agent>

[0042] The anisotropic conductive film of the present invention contains an anionic latent curing agent for anionic polymerization of an epoxy compound. Examples of the anionic latent curing agent include: imidazole-based curing agents, hydrazide-based curing agents, boron trifluoride-amine complex-based curing agents, amine imide-based curing agents, polyamine salt-based curing agents, dicyandiamide-based curing agents, and substances obtained by modifying them. Two or more of these can also be used in combination. In addition, if necessary, it can also be microencapsulated by a conventional method and used. In the substance obtained by microencapsulating the curing agent (microcapsule-type curing agent), an epoxy compound and an anionic curing agent are contained, and the microcapsule is broken by heating, thereby reacting the curing agent component with the epoxy compound. In 100 parts by mass of the microcapsule-type curing agent, usually 20 to 50 parts by mass of the curing agent and 80 to 50 parts by mass of the epoxy resin are contained.

[0043] As the anionic latent curing agent, a microcapsule-type latent curing agent containing an epoxy compound and an anionic curing agent can be suitably used. For example, NOVACURE HXA3932HP, NOVACURE HX3941HP, etc. can be exemplified.

[0044] When the total amount of the non-volatile component of the epoxy compound is set to 100% by mass, the content of the anionic latent curing agent in the anisotropic conductive film is preferably 10% by mass or more, more preferably 15% by mass or more, and further preferably 20% by mass or more. There is no particular limitation on the upper limit of this content, and it is preferably 50% by mass or less, more preferably 45% by mass or less, and further preferably 40% by mass or less.

[0045] <Silane Coupling Agent>

[0046] The anisotropic conductive film of the present invention contains: a silane coupling agent having two or more mercapto groups in one molecule and an organic chain as the main chain.

[0047] The silane coupling agent used in the anisotropic conductive film of the present invention is not particularly limited as long as it has two or more mercapto groups, one or more alkoxysilyl groups, and an organic chain having mercapto and alkoxysilyl groups as side chains or terminal groups in one molecule. The silane coupling agent having two or more mercapto groups can improve the adhesion to the metal wiring of the FPC, and thus can improve the adhesion strength.

[0048] The alkoxysilyl group of the silane coupling agent is preferably a trialkoxysilyl group, more preferably a trimethoxysilyl group.

[0049] As a suitable embodiment of the silane coupling agent, the compound represented by the following formula (1) can be exemplified.

[0050]

[0051] In the above formula (1), R is selected from a hydroxyl group, a mercapto group, or an alkoxysilyl group represented by the following formula (2), and n is an integer of 1 or more and 100 or less. Among them, at least one of R is an alkoxysilyl group represented by the following formula (2), and at least two of R are mercapto groups.

[0052]

[0053] In the above formula (2), R' is an alkyl group having 1 to 6 carbon atoms, X is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and m is an integer of 1 to 3.

[0054] In addition, as a suitable embodiment of the silane coupling agent, the compound represented by the following formula (3) can be exemplified.

[0055]

[0056] In the above formula (3), R is selected from a hydroxyl group, a mercapto group, or an alkoxysilyl group represented by the following formula (4), a is an integer of 4 or more and 10 or less, and b, c, and d are integers of 0 or more and 10 or less. Among them, at least one of R is an alkoxysilyl group represented by the following formula (4), and at least two of R are mercapto groups.

[0057]

[0058] In the above formula (4), R' is an alkyl group having 1 to 6 carbon atoms, X is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and m is an integer of 1 to 3.

[0059] In the silane coupling agent used in the anisotropic conductive film of the present invention, the ratio of the number of mercapto groups to the number of alkoxysilyl groups is preferably 2 or more, more preferably 3 or more. Further, the ratio of the number of mercapto groups to the number of alkoxysilyl groups is preferably 10 or less, more preferably 7 or less. By making the ratio of the number of mercapto groups to the number of alkoxysilyl groups 2 or more, the compatibility in the binder composition as an organic component is excellent, and the adhesion can be improved by binding to the binder composition or the insulating resin of the FPC. On the other hand, by making the ratio of the number of mercapto groups to the number of alkoxysilyl groups 10 or less, the adhesive strength to inorganic components such as glass substrates can be improved.

[0060] Since the main chain of the silane coupling agent used in the anisotropic conductive film of the present invention is an organic chain, its compatibility and adhesion with the binder composition are excellent.

[0061] Specific examples of the silane coupling agent used in the anisotropic conductive film of the present invention include X-12-1154, X-12-1156, etc. manufactured by Shin-Etsu Chemical Co., Ltd.

[0062] The weight average molecular weight in terms of polystyrene of the silane coupling agent used in the anisotropic conductive film of the present invention is preferably 500 to 3000. If the weight average molecular weight in terms of polystyrene is less than 500, it may be difficult to manufacture, and if the weight average molecular weight in terms of polystyrene is greater than 3000, the operability during manufacturing may deteriorate.

[0063] In the anisotropic conductive film of the present invention, when the non-volatile components in the anisotropic conductive film are set to 100% by mass, the content of the silane coupling agent is preferably 0.5% by mass or more and 2.0% by mass or less. If the content of the silane coupling agent is less than 0.5% by mass or exceeds 2.0% by mass, the indentation state deteriorates and the conduction resistance may increase. The blending amount of the silane coupling agent is more preferably 1.2% by mass or more and 1.8% by mass or less. By making the blending amount of the silane coupling agent 1.2% by mass or more and 1.8% by mass or less, the storage stability is dramatically improved.

[0064] <Conductive particles>

[0065] The anisotropic conductive film of the present invention contains conductive particles. As the conductive particles, known conductive particles used in anisotropic conductive films can be used. Examples of the 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; coated particles in which the surfaces of particles of metal oxides, carbon, graphite, glass, ceramics, resins, etc. are coated with a metal. In the case of using metal-coated resin particles in which the surface of resin particles is coated with a metal, examples of the material of the resin particles include: epoxy resin, phenolic resin, acrylic resin, styrene-acrylonitrile (AS) resin, benzoguanamine resin, divinylbenzene-based resin, styrene-based resin, etc. It should be noted that for the conductive particles, if the conduction performance after connection is not hindered, in order to avoid the risk of short circuit between terminals, an insulating film may be further coated on the surface of the above particles, or insulating particles may be attached to the surface, etc. to perform insulation treatment. These conductive particles can be used alone or in combination of two or more kinds.

[0066] There is no particular limitation on the average particle diameter of the conductive particles, which can be appropriately determined according to the purpose. It is preferably 40 μm or less, more preferably 30 μm or less, further preferably 25 μm or less, and even more preferably 20 μm or less. There is no particular limitation on the lower limit of the average particle diameter, which is preferably 1 μm or more, more preferably 2 μm or more, and further preferably 3 μm or more. The average particle diameter of the conductive particles can be observed, for example, by scanning electron microscopy (SEM). The particle diameters of a plurality of (n≥10) conductive particles are measured, and their average value is calculated. Alternatively, it can also be the measured value (N = 1000 or more) measured using an image-based particle size distribution measuring device (for example, FPIA-3000 (Malvern Corporation)).

[0067] There is no particular limitation on the content of the conductive particles in the anisotropic conductive film, which can be appropriately determined according to the purpose. It is preferably 1% by mass or more, more preferably 2% by mass or more, and further preferably 3% by mass or more. From the viewpoint of obtaining the desired anisotropic conductivity, the upper limit of this content is preferably 20% by mass or less, more preferably 15% by mass or less, further preferably 10% by mass or less, and even more preferably 7% by mass or less.

[0068] As needed, the anisotropic conductive film of the present invention may further contain other components. As the components involved, for example, there may be mentioned: organic fillers (e.g., butadiene-based rubber particles, acrylic-based rubber particles, silicone-based rubber particles), insulating inorganic fillers (e.g., silica fillers), etc. fillers that do not hinder conduction, surface modifiers, flame retardants, coupling agents, colorants, and other known additives used in the manufacture of the anisotropic conductive film. From the viewpoint of improving the bonding strength, it is preferable to add organic fillers such as butadiene-based rubber particles. When adding organic fillers such as butadiene-based rubber particles, it is preferable to use fillers with a particle size of about 0.1 μm to 2.0 μm.

[0069] The anisotropic conductive film of the present invention has a high bonding strength at a low bonding temperature without using a radically polymerizable (meth)acrylic compound. The anisotropic conductive film of the present invention can also be suitably used for bonding that requires a high bonding strength due to different substrates such as FOG mounting where an FPC is mounted on a glass substrate.

[0070] [Morphology of Anisotropic Conductive Film]

[0071] The anisotropic conductive film of the present invention can be composed of a single layer or multiple layers. In the case of being composed of multiple layers, it may also include a first adhesive layer composed of the anisotropic conductive film of the present invention and a second adhesive layer composed of the anisotropic conductive film of the present invention provided on the first adhesive layer. In addition, a layer different from the anisotropic conductive film of the present invention may be provided on the first adhesive layer composed of the anisotropic conductive film of the present invention. Or, a layer different from the present invention may be sandwiched between the first adhesive layer composed of the anisotropic conductive film of the present invention and the second adhesive layer composed of the anisotropic conductive film of the present invention. The layer different from the anisotropic conductive film of the present invention may be a layer composed of an anisotropic conductive film different from the present invention or a resin layer that is a non-adhesive layer (not contributing to adhesion). The layer different from the present invention is preferably insulating.

[0072] [Manufacturing Method of Anisotropic Conductive Film]

[0073] The anisotropic conductive film can be manufactured, for example, as follows: The material of the anisotropic conductive film of the present invention is mixed with an organic solvent as needed to prepare a coating material, and then the coating material is coated on a release substrate and further dried to form a film layer. The coating of the coating material can be carried out using a coating device such as a bar coater. Known coating methods for anisotropic conductive films such as the doctor blade method can be used. In the case of manufacturing an anisotropic conductive film composed of multiple layers, the above coating and drying processes can be repeatedly carried out multiple times. Or they can be manufactured separately and laminated by lamination or the like.

[0074] The release substrate may be any film-like material that can support the anisotropic conductive film and can be released from the anisotropic conductive film at a desired timing, and is not particularly limited. As the material of the release substrate, for example, polyester such as polyethylene terephthalate (PET), polyolefin such as polypropylene (PP), poly-4-methyl-1-pentene (PMP), polytetrafluoroethylene (PTFE) and other plastic materials can be used. The release substrate may also be a substrate having a release layer on the surface on the side joined to the adhesive film, and the release layer may contain a release agent such as silicone resin or polyolefin resin, for example.

[0075] There is no particular limitation on the thickness of the release substrate, and it is preferably 100 μm or less, more preferably 80 μm or less, still more preferably 60 μm or less, and particularly preferably 50 μm or less. There is no particular limitation on the lower limit of the thickness of the release substrate, and from the viewpoint of the operability during the manufacture of the adhesive film and the notch processing, it is preferably 8 μm or more.

[0076] There is no particular limitation on the thickness of the anisotropic conductive film of the present invention, and it can be appropriately determined according to the purpose. It is preferably 1 μm or more, more preferably 3 μm or more, still more preferably 5 μm or more. There is no particular limitation on the upper limit of the thickness of the adhesive layer, and it is preferably 100 μm or less, more preferably 80 μm or less, still more preferably 60 μm or less, still more preferably 50 μm or less, and particularly preferably 40 μm or less. In the case of multi-layer lamination, it is the total thickness.

[0077] The anisotropic conductive film can be notch-processed to have a desired width. During the notch processing, in order to prevent the thin film layer from being contaminated by cutting chips or the like, a cover film can be provided on its exposed surface. The thickness in this case can be appropriately selected according to the purpose. As the cover film, a known film used in the notch processing of the anisotropic conductive film can be used. For the cover film, in addition to manufacturing processes such as notch processing, as a product for connection use, in order to prevent contamination during use, it can also be provided separately from the release substrate. In this case, the cover film preferably has peelability, and the thickness is preferably the same as or thinner than the release substrate.

[0078] [Connection structure]

[0079] By using the anisotropic conductive film of the present invention, a connection structure obtained by bonding electronic components to each other can be manufactured. The present invention includes a connection structure in which a first electronic component and a second electronic component are connected by the anisotropic conductive film of the present invention.

[0080] As the first electronic component, for example, it can be a general printed circuit board, and examples include: rigid substrates, glass substrates, ceramic substrates, plastic substrates, FPCs, etc. In addition, as the second electronic component, examples include: semiconductor components other than FPCs, IC chips, and IC chips. There are no particular limitations on the electronic components, nor are there any particular limitations on the use of the connection structure. For example, it can be used in portable information terminals or for electrical installations in vehicles. In the present invention, as an example, various connection structures such as FOB, FOG, FOP, FOF, COG, and COP can be manufactured. In particular, it is preferably applied to FOG and FOP.

[0081] [Manufacturing Method of Connection Structure]

[0082] The manufacturing method of the connection structure of the present invention is not particularly limited as long as it can manufacture a connection structure formed by connecting a first electronic component and a second electronic component through the anisotropic conductive film of the present invention. Hereinafter, an example of the method for manufacturing the connection structure of the present invention will be shown.

[0083] In one embodiment, the manufacturing method of the connection structure of the present invention includes: a step of interposing the anisotropic conductive film of the present invention between a first electronic component and a second electronic component and performing press bonding.

[0084] First, place the first electronic component on a stage, set the anisotropic conductive film or adhesive film of the present invention thereon, and then place the second electronic component. Here, after setting the anisotropic conductive film of the present invention on the first electronic component placed on the stage, align the electrodes of the first electronic component and the electrodes of the second electronic component in a facing manner, and perform temporary press bonding from the second electronic component side using a press bonding tool. The temperature, pressure, and time during temporary press bonding can be appropriately determined according to the specific design. For example, it can be set to 60 - 80°C, 0.5 - 2 MPa, and 0.5 - 2 seconds. Before performing the formal press bonding described later, by performing such temporary press bonding, the electronic components (the conduction portions of each component) can be more accurately aligned and connected to each other, so it is appropriate. By performing temporary press bonding, it is possible to expect to suppress the positional deviation during the formal press bonding with a higher pressure.

[0085] After temporary press bonding, perform formal press bonding from the second electronic component side using a press bonding tool. The temperature, pressure, and time during formal press bonding can be any known conditions used when bonding electronic components using an adhesive film and can be appropriately determined according to the specific design. For example, even for press bonding at a low temperature (e.g., 200°C or lower, 180°C or lower) and for a short time (e.g., 10 seconds or shorter, 8 seconds or shorter), the first electronic component and the second electronic component can be well bonded.

[0086] It should be noted that, whether it is temporary crimping or formal crimping, a buffer material (such as a buffer sheet) can be provided between the second electronic component and the crimping tool. The buffer material can be appropriately adjusted and determined according to the combination of electronic components, including whether it is used or not.

[0087] The anisotropic conductive film of the present invention has high adhesive strength even at a low bonding temperature. For example, in the case of bonding under the bonding conditions of 180 °C, 3 MPa, and 8 seconds, the connection structure of the FPC and the glass substrate manufactured using the anisotropic conductive film of the present invention, whether using the anisotropic conductive film (bonding film) just after manufacturing or the anisotropic conductive film (bonding film) stored for a certain period of time in a normal temperature or refrigerated environment, can exhibit an adhesive strength of 10 N / cm or more in a 90-degree peel test.

[0088] Examples

[0089] Hereinafter, the present invention will be specifically described by showing examples. However, the present invention is not limited to the examples shown below. In the following description, unless otherwise specified, "parts" and "%" indicating amounts refer to "parts by mass" and "mass %", respectively.

[0090] [Example 1]

[0091] - Preparation of anisotropic conductive film -

[0092] To 40.84 parts by mass of a microcapsule-type curing agent (trade name: NOVACURE HXA3932HP, manufactured by Asahi Kasei Corporation) containing 35 mass % of an anionic latent curing agent and containing a bisphenol F-type epoxy compound and a bisphenol A-type liquid epoxy resin in a total proportion of 65 mass %, 7.21 parts by mass of a naphthalene-type epoxy compound (HP trade name: HP4032D, manufactured by DIC Corporation), 21.12 parts by mass of a phenoxy resin (trade name: YP-50, manufactured by Nippon Steel Chemical Materials Co., Ltd., Mw = 60,000 - 80,000), 7.40 parts by mass of a (meth)acrylate resin (trade name: SG-80H, manufactured by Nagase ChemteX Corporation), 17.41 parts by mass of butadiene-based rubber particles (trade name: RKB5515B, manufactured by Resinous Kasei Corporation, average particle diameter 0.5 μm), 1.50 parts by mass of a silane coupling agent (trade name: X-12-1154, manufactured by Shin-Etsu Chemical Co., Ltd.), and 4.52 parts by mass of conductive particles (trade name: Bright, manufactured by Nippon Chemical Industry Co., Ltd., average particle diameter 4 μm), PMA was added as a solvent to make the total solid content reach 43.4%, and they were uniformly mixed to obtain a coating material for the anisotropic conductive film.

[0093] - Fabrication of anisotropic conductive film -

[0094] As the release substrate, a PET film (thickness: 50 μm) was prepared. An anisotropic conductive film was uniformly coated on this release substrate, and the thickness of the dried adhesive film (adhesive layer) was made 18 μm. Thereafter, it was dried in an oven at 70 °C for 5 minutes to form an adhesive layer on the release substrate. Then, a cover film was laminated on the exposed surface of the adhesive layer at 45 °C.

[0095] [Examples 2 to 6 and Comparative Examples 1 to 2]

[0096] Except for changing the blending amounts of silane coupling agents and the like as shown in Table 1, the operation was carried out in the same manner as in Example 1 to prepare a coating material and produce an anisotropic conductive film.

[0097] [Comparative Examples 3 to 5]

[0098] The silane coupling agent was changed to a silane coupling agent having two epoxy groups in one molecule (trade name: X-12-981S, manufactured by Shin-Etsu Chemical Co., Ltd.), a silane coupling agent having one epoxy group in one molecule (trade name: A187, manufactured by Dow Corning Toray Co., Ltd.), and a silane coupling agent having two or more isocyanate groups in one molecule (trade name: X-12-1159L, manufactured by Shin-Etsu Chemical Co., Ltd.), and the blending amounts of the respective components were changed as shown in Table 1. Otherwise, the operation was carried out in the same manner as in Example 1 to prepare a coating material and produce an anisotropic conductive film.

[0099] [Comparative Example 6]

[0100] Except for blending a tetrafunctional thiol compound (trade name: Karenz MTPE1, manufactured by Showa Denko K.K.) instead of the silane coupling agent and changing the blending amounts of the respective components as shown in Table 1, the operation was carried out in the same manner as in Example 1 to prepare a coating material and produce an anisotropic conductive film.

[0101] Hereinafter, the test and evaluation methods will be described.

[0102] <Temporary adhesion evaluation>

[0103] The produced anisotropic conductive film was pasted on the edge of a glass substrate, and after uniformly applying a force on a hot plate at 45 °C, the PET film as the release substrate was peeled off (Step 1). The metal wiring portions of a flexible printed circuit board (thickness: 50 μm) were connected and bonded so that the exposed surface of the anisotropic conductive film was completely covered (Step 2). The evaluation was carried out in three stages of "○", "△", and "×". In practical applications, it is sufficient if it is "△" or above, and "○" is preferred.

[0104] "○" ··· Satisfies the following two conditions.

[0105] In Process 1, the release substrate can be peeled off at room temperature, and the anisotropic conductive film can be perfectly adhered to the glass substrate.

[0106] In Process 2, the metal wiring portion of the FPC can be connected and bonded to the anisotropic conductive film at room temperature.

[0107] “△”··· satisfies the following two conditions.

[0108] In Process 1, the release substrate cannot be peeled off at room temperature, but can be peeled off on a hot plate, and the anisotropic conductive film can be perfectly adhered to the glass substrate.

[0109] In Process 2, the metal wiring portion of the FPC cannot be connected to the anisotropic conductive film at room temperature, but can be connected and bonded to the metal wiring portion on a hot plate.

[0110] “×”··· satisfies any one of the following.

[0111] In Process 1, the anisotropic conductive film cannot be adhered to the glass substrate even on a hot plate.

[0112] In Process 2, the metal wiring portion of the FPC cannot be connected to the anisotropic conductive film even on a hot plate.

[0113] <Evaluation of conduction resistance>

[0114] -Fabrication of connection structure-

[0115] After processing the cut of the adhesive film produced in the examples and comparative examples to a width of 1.0 mm, the cover film was peeled off. Then, the anisotropic conductive film was adhered to the edge of the glass substrate in such a way that the exposed surface of the anisotropic conductive film was joined to the ITO glass substrate (each with a thickness of 0.7 mm), and a force was uniformly applied on a hot plate at 45°C. After that, the release substrate was peeled off, and the metal wiring portion of the flexible printed circuit board (FPC; thickness 50 μm) was connected and bonded so that the exposed surface of the anisotropic conductive film was completely covered. The anisotropic conductive film was interposed between the FPC and the glass substrate and thermocompression bonded, and all the opposing conduction portions of the FPC and the glass substrate were bonded using the cured product of the adhesive layer, thereby obtaining a connected connection structure. The conditions for thermocompression bonding were 180°C, 3 MPa, and 8 seconds.

[0116] For the obtained connection structure, the conduction resistance was measured immediately after bonding and after being kept in a pressure cooker device (110°C, 85% RH) for 32 hours.

[0117] <Indentation reliability>

[0118] Instead of using a glass substrate, a bonding film was pasted on the edge of the glass substrate in such a way that the exposed surface of the adhesive layer was joined to an AlMoIZO glass substrate (thickness 0.7 mm), and force was uniformly applied on a hot plate at 45°C. After that, the release substrate was peeled off, and the metal wiring portion of a flexible printed circuit board (FPC; thickness 50 μm) was connected and bonded so that the exposed surface of the adhesive layer was completely covered. With the adhesive layer interposed between the FPC and the glass substrate, thermocompression bonding was performed under the conditions of 180°C, 3 MPa, and 8 seconds, and all the opposing conduction portions of the FPC and the glass substrate were bonded using the cured product of the adhesive layer, thereby obtaining a connected structure body.

[0119] The connection conditions were the same as those for the connection body using a glass substrate. The indentation strength of the particles captured by the bumps of the connected body was confirmed using a differential interference microscope. The case where the indentation was more clearly observed was evaluated as "○", the case where the indentation was clearly observed was evaluated as "△", and the case where the indentation was not clearly observed was evaluated as "×". In practical applications, it is sufficient if it is "△" or above, and "○" is preferred.

[0120] <Floating of the anisotropic conductive layer>

[0121] -Fabrication of the connection structure body-

[0122] After the anisotropic conductive films fabricated in the examples and comparative examples were cut to a width of 1.0 mm, the cover film was peeled off. Then, a bonding film was pasted on the edge of the glass substrate in such a way that the exposed surface of the adhesive layer was joined to a SiN glass substrate or an ITO glass substrate (thickness 0.7 mm each), and force was uniformly applied on a hot plate at 45°C. After that, the release substrate was peeled off, and the metal wiring portion of a flexible printed circuit board (FPC; thickness 50 μm) was connected and bonded so that the exposed surface of the adhesive layer was completely covered. With the anisotropic conductive film interposed between the FPC and the glass substrate, thermocompression bonding was performed, and all the opposing conduction portions of the FPC and the glass substrate were bonded using the cured product of the anisotropic conductive film, thereby obtaining a connected structure body. The conditions for thermocompression bonding were 180°C, 3 MPa, and 8 seconds.

[0123] For the obtained connection structure body, the floating state of the anisotropic conductive layer was visually confirmed immediately after bonding and after being kept in a pressure cooker device (110°C, 85% RH) for 32 hours. The evaluation was carried out in three stages: no floating (○), slight floating (△), and floating (×).

[0124] <Evaluation of the bonding strength>

[0125] For the connection structure whose crimping state was evaluated, the adhesive strength 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 FPC with a length of 1.0 cm was grasped by a jig, and the load (N / cm) was measured when the FPC was peeled off vertically at a speed of 50 mm / min at room temperature (25 °C) until it was peeled off from the glass substrate. It should be noted that a TENSILON testing machine (manufactured by ORIENTEC CO., LTD.: STA-1150) was used in the measurement. The adhesive strength was also evaluated in the same manner for the connection structure maintained in a pressure cooker device (110 °C, 85% RH) for 32 hours and the connection structure using an anisotropic conductive film maintained in an oven (55 °C) for 12 hours.

[0126] The constituent components and evaluation results of the examples and comparative examples are shown in Table 1.

[0127] [Table 1]

[0128]

[0129] From the results in Table 1, it was confirmed that when using a silane coupling agent having two or more mercapto groups in one molecule and an organic chain as the main chain, even the adhesion at low temperature has a high adhesive strength and the conduction is also good. In addition, in Examples 1, 4, and 5 in which 1.2 mass% or more and 1.8 mass% or less of a silane coupling agent having two or more mercapto groups in one molecule and an organic chain as the main chain was blended, it was confirmed that high adhesive strength was also exhibited after the pressure cooker test and after film aging, and extremely high storage stability was achieved.

[0130] In addition, from Comparative Examples 3 to 5, it was confirmed that when using a silane coupling agent having an organic chain as the main chain and having one or two or more reactive groups other than mercapto groups (such as epoxy groups, isocyanate groups) in one molecule, there are problems in terms of temporary adhesiveness, and problems such as conduction resistance, indentation, and lifting occur.

[0131] Moreover, in the anisotropic conductive film (Comparative Example 6) in which a tetrafunctional thiol compound was blended to confirm the influence of mercapto groups, problems such as temporary adhesiveness, conduction resistance, indentation, and lifting were confirmed.

Claims

1. An anisotropic conductive film, comprising: An adhesive composition containing an epoxy compound and a film-forming component; An anionic latent curing agent for curing the epoxy compound; A silane coupling agent having two or more mercapto groups in one molecule and an organic chain as the main chain; and Conductive particles.

2. The anisotropic conductive film according to claim 1, wherein The blending amount of the silane coupling agent is 0.5% by mass or more and 2.0% by mass or less.

3. The anisotropic conductive film according to claim 1, wherein, The blending amount of the silane coupling agent is 1.2% by mass or more and 1.8% by mass or less.

4. A connection structure, which is formed by connecting a first electronic component and a second electronic component through the anisotropic conductive film according to claim 1.

5. Method for manufacturing a connecting structure, comprising: A step of interposing the anisotropic conductive film according to claim 1 between the first electronic component and the second electronic component and performing crimping.

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