JP5581605B2 - Method for producing anisotropic conductive adhesive film - Google Patents

Description

  The present invention is excellent in electrical connection of electrodes having a small area in electrical connection of fine patterns, and is less likely to cause dielectric breakdown (short circuit) between fine wirings, and can be electrically connected to semiconductor chips having different electrode patterns. The present invention relates to an anisotropic conductive adhesive film having a high storage stability and capable of providing a long-term reliability.

  An anisotropic conductive adhesive film is a film in which conductive particles are dispersed in an insulating adhesive, in other words, a connection between a liquid crystal display and a semiconductor chip or TCP, or a connection between FPC and TCP, an FPC and a printed wiring board, For example, it is widely used for connecting a liquid crystal display of a notebook personal computer or a cellular phone and a control IC. Recently, a semiconductor chip is directly connected to a printed circuit board or It is also used for flip chip mounting to be mounted on a flexible wiring board (see Patent Documents 1, 2, and 3 below).

  In recent years, the dimensions of connected wiring patterns and electrode patterns have been increasingly miniaturized in this field. On the other hand, the width of the miniaturized wiring or electrode is sometimes miniaturized to a level of several tens of μm. On the other hand, the average particle diameter of the conductive particles used so far is several μm, which is the same level as the line width of the wiring or electrode. To 10 μm level particles. Then, when the dimension of the electrode pattern to be connected is reduced, in the anisotropic conductive adhesive film in which conductive particles are randomly dispersed and arranged, there is a deviation in the distribution of the conductive particles. A case where the particles are arranged at positions where no particles exist and are not electrically connected is inevitable as a probability theory.

  As a technique for solving this problem, a technique for arranging particles has been proposed. Conductive using a method of spreading conductive particles attached to the surface and embedding the conductive particles in the surface layer of the insulating adhesive (refer to Patent Document 4 below) or a conductive particle adsorption jig having suction holes arranged in a predetermined manner. Disclosed are a method of arranging particles and embedding them in an insulating adhesive (hereinafter referred to as Patent Document 5), a method of arranging conductive particles using stretching and embedding them in an insulating adhesive (hereinafter referred to as Patent Document 6), and the like. However, usable electrodes and connection conditions are limited in order to connect the conductive particles arranged at the corners without breaking the arrangement state against the flow of the insulating resin at the time of connection. This is a large practical limitation. On the other hand, the technique corresponding to the connection of the fine pattern which suppresses the flow at the time of the connection of the arranged electroconductive particle is disclosed (refer patent document 7 hereafter).

On the other hand, in this field, a thermosetting adhesive such as an epoxy resin is used as the adhesive in consideration of the reliability of the circuit connection portion. Until the thermosetting adhesive for circuit connection is used, the thermosetting resin and the curing agent exist stably in an unreacted state, and at the time of use, in order to minimize productivity and damage to circuit members It is required to be cured at a low temperature in a short time. In order to achieve both the storage stability and curability, the hardener used in the thermosetting adhesive is a microcapsule type in which a latent hardener, especially a highly reactive hardener, is coated with a capsule film. The latent curing agent is generally used. On the other hand, in order to form a thermosetting adhesive into a film, it is necessary to uniformly mix the film-forming polymer in the thermosetting adhesive and form the film. In general, a coating solution obtained by dissolving or uniformly dispersing a curable adhesive composition in a solvent is applied onto a peelable substrate, and the solvent is removed by heating to form a film. Here, the microcapsule-type curing agent is also dispersed in the coating liquid containing the solvent, and further subjected to heating to remove the solvent. However, the microcapsule type curing agent is contacted with or heated with water contained in the solvent or the coating liquid. Is a factor that swells or breaks the capsule film of a microcapsule type curing agent and lowers the storage stability, and various studies have been made (see Patent Documents 8 and 9 below).
However, the anisotropic conductive adhesive film of the prior art has not yet been achieved to achieve high storage stability while exhibiting the low-temperature short-time curability that is increasingly demanded, and improvements are required.

Japanese Patent Laid-Open No. 03-107888 Japanese Patent Laid-Open No. 04-366630 JP-A-61-195179 JP 2000-151084 A JP 2002-332461 A International Publication No. WO2005 / 054388 JP 2007-217503 A JP 05-295329 A JP 2000-80146 A

  The problem to be solved by the present invention is that, in the electrical connection of a fine pattern, the electrical connectivity of a small area electrode is excellent, and dielectric breakdown (short) between fine wirings hardly occurs and long-term reliability is given. It is an object to provide an anisotropic conductive adhesive film that can be connected, can achieve both low-temperature short-time curability and storage stability, and has good adhesion to a substrate.

As a result of intensive studies to solve the above problems, the inventors of the present invention are very important in the heating step for removing the solvent from the coating liquid, while stretching in the elastic region of the peelable substrate. It has been found that the above problem can be solved by removing the solvent by heating, and the present invention has been completed.
By removing the solvent while stretching, high storage stability can be obtained even with a highly active curing agent, and the above problem has been solved. It was a discovery that should be done.

That is, the present invention is as follows.
[1] In a method for producing an anisotropic conductive adhesive film in which a conductive layer made of a binder resin having conductive particles arranged in a single layer on a surface layer and an insulating adhesive laminated on at least one surface of the conductive layer, the conductive particles The coefficient of variation of the center-to-center distance is from 0.05 to 0.5, the 180 ° C. melt viscosity of the insulating adhesive is lower than the 180 ° C. melt viscosity of the binder resin, and the method comprises: Process of:
A step of preparing a coating liquid in which the insulating adhesive containing a thermosetting resin, a microcapsule-type curing agent, and a film-forming polymer is dissolved or dispersed in a solvent;
A step of applying the coating liquid on a peelable substrate;
A film-forming step in which the peelable substrate coated with the coating liquid is heated while being stretched within the elastic region of the peelable substrate to volatilize the solvent,
The manufacturing method of the said anisotropically conductive adhesive film characterized by including.

  [2] The average distance between the centers of the conductive particles is 2 μm or more and 20 μm or less, and 1.5 times or more and 5 times or less of the average particle diameter of the conductive particles. A method for producing an anisotropic conductive adhesive film.

  [3] The method for producing an anisotropic conductive adhesive film according to [1] or [2], wherein the binder resin has a 180 ° C. melt viscosity of 50 Pa · s or more.

  [4] The method for producing an anisotropic conductive adhesive film according to any one of [1] to [3], wherein the thermosetting resin is an epoxy resin.

  [5] The method for producing an anisotropic conductive adhesive film according to any one of [1] to [4], wherein the microcapsule type curing agent has a structure in which the periphery of the curing agent is coated with a polymer compound. .

  [6] The method for producing an anisotropic conductive adhesive film according to any one of [1] to [5], wherein the activation temperature of the microcapsule type curing agent is 60 ° C. or higher and 100 ° C. or lower.

  [7] The water content in the coating liquid is any one of [1] to [6], which is 0.5% by mass or more and 10% by mass or less with respect to the microcapsule-type curing agent. A method for producing an anisotropic conductive adhesive film.

  [8] The method for producing an anisotropic conductive adhesive film according to any one of [1] to [7], wherein an average particle diameter of the conductive particles is 0.5 μm or more and 10 μm or less.

  [9] The method for producing an anisotropic conductive adhesive film according to any one of [1] to [9], wherein the heating temperature in the film forming step is 50 ° C. or higher and 90 ° C. or lower.

  In the electrical connection of the fine pattern, the present invention is excellent in electrical connectivity of electrodes having a small area, is less likely to cause dielectric breakdown (short) between fine wirings, and can provide a connection that provides long-term reliability. In addition, both low-temperature short-time curability and storage stability can be achieved, and further, there is an effect of having good adhesiveness to a substrate.

Hereinafter, the present invention will be specifically described.
The present invention relates to a conductive layer made of a binder resin in which conductive particles are arranged in a single layer on a surface layer, and a method for producing an anisotropic conductive adhesive film in which an insulating adhesive is laminated on at least one surface of the conductive layer. The conductive layer used in the present invention is made of a binder resin in which conductive particles are arranged in a single layer on the surface layer.
“Arranged in the surface layer” means a state in which a part or all of the conductive particles are embedded in the surface of the binder resin. Alternatively, the binder resin may be thinner than the particle size of the conductive particles, and the conductive particles may be exposed above and below the binder resin. When a part of the conductive particles is embedded, the conductive particles are less likely to be detached from the binder resin if 1/3 or more of the average particle diameter is embedded in the binder resin. This is preferable because it has an effect of suppressing poor connection. It is more preferable to embed 1/2 or more, and it is further preferable to embed 2/3 or more. On the other hand, when the conductive particles are completely embedded in the binder resin, the thickness of the binder resin between the conductive particles and the surface of the binder resin is to suppress the movement of the conductive particles during pressurization for connection. The average particle size of the conductive particles is preferably 1.0 times or less. More preferably, it is 0.8 times or less, More preferably, it is 0.5 times or less, More preferably, it is 0.3 times or less, Especially preferably, it is 0.1 times or less. In the present invention, the conductive particles are arranged in a single layer on the binder resin in order to ensure the conductivity in the thickness direction and the insulation in the plane direction (hereinafter also referred to as “anisotropic conductivity”) at a high level. Here, “disposed in a single layer” means that the variation in the center height of the conductive particles is less than twice the average particle diameter of the conductive particles. The variation in the center height with respect to the average particle diameter of the conductive particles is preferably close to 0, more preferably 1 time or less, still more preferably 0.8 times or less, and still more preferably 0.6 times or less. Here, the variation in the center height of the conductive particles is a standard deviation of the distance from the binder resin surface to the center of the conductive particles. When the center of the conductive particles is not embedded in the binder resin, the center height is This is the value minus the distance.

In the present invention, since the conductive particles exist as a single layer on the surface layer of the binder resin, in particular, the connection between a high connection height and a substantially flat connection, such as a connection between a semiconductor chip and a liquid crystal panel. In this case, it is possible to prevent the arranged conductive particles from largely moving at the time of connection.
The anisotropic conductive adhesive film produced according to the present invention has a high anisotropic conductivity because the conductive particles are arranged at a specific center distance and the center distance is arranged with a specific coefficient of variation. Have. That is, the average distance between the centers of the conductive particles of the anisotropic conductive adhesive film produced according to the present invention is preferably 2 μm or more and 20 μm or less, and 1.5 times or more and 5 times the average particle diameter of the conductive particles. When the distance between the centers is 2 μm or more and 1.5 times or more the average particle diameter of the conductive particles, the insulation in the surface direction, that is, the insulation between adjacent electrodes can be maintained at a high level. . On the other hand, by setting the distance between centers to 20 μm or less and 5 times or less the average particle diameter of the conductive particles, a conductive particle density capable of maintaining the electrical conductivity in the thickness direction, that is, the electrical connectivity between the connection electrodes, is obtained. Therefore, high performance as an anisotropic conductive adhesive film can be exhibited. The average distance between the centers of the conductive particles is preferably 2.5 μm or more and 18 μm or less, more preferably 3 μm or more and 16 μm or less, further preferably 3.5 μm or more and 15 μm or less, and particularly preferably 4 μm or more and 13 μm or less. The average particle diameter is preferably 1.55 times to 4.6 times, more preferably 1.6 times to 4.3 times, and still more preferably 1.65 times to 4.0 times. .

  The “coefficient of variation in the distance between the centers of the conductive particles” is a value obtained by dividing the standard deviation of the distance between the centers of the conductive particles by the average value. In the present invention, it is 0.05 or more and 0.5 or less. Preferably it is 0.1 or more and 0.4 or less, More preferably, it is 0.11 or more and 0.36 or less, More preferably, it is 0.12 or more and 0.34 or less, More preferably, it is 0.13 or more and 0.32 or less, Especially preferably Is 0.14 or more and 0.3 or less. By making the coefficient of variation 0.05 or more, there is no flow of conductive particles at the time of connection, which adversely affects the electrical connectivity between the connection electrodes. Variations in the number of conductive particles to be captured for each electrode can be kept small, variations in connection resistance for each electrode are small, and stable connection can be obtained.

As the conductive particles used in the present invention, metal particles, particles made of carbon, particles obtained by coating a polymer core material with a metal thin film, and the like can be used.
As the metal particles, for example, simple substances such as gold, silver, copper, nickel, aluminum, zinc, tin, lead, solder, indium, and palladium, or two or more kinds of these metals are combined in a layered or inclined manner. Particles are exemplified.
Particles with a polymer core coated with a metal thin film include epoxy resin, styrene resin, silicone resin, acrylic resin, polyolefin resin, melamine resin, benzoguanamine resin, urethane resin, phenol resin, polyester resin, divinylbenzene crosslinked product, NBR , SBR and other polymer core materials combined with one or more polymers, gold, silver, copper, nickel, aluminum, zinc, tin, lead, solder, indium, palladium, etc. The particle | grains which metal-coated by plating etc. in combination of 2 or more types are illustrated. The thickness of the metal thin film is preferably in the range of 0.005 μm to 1 μm from the viewpoint of connection stability and particle cohesion. It is preferable in terms of connection stability that the metal thin film is uniformly coated. Particles obtained by further insulating coating the surfaces of these conductive particles can also be used.

The average particle diameter of the conductive particles is preferably in the range of 0.5 μm or more and 10 μm or less from the viewpoint of compatibility between conductivity and insulation and particle aggregability. More preferably, they are 1 micrometer or more and 7 micrometers or less, More preferably, they are 1.5 micrometers or more and 6 micrometers or less, More preferably, they are 2 micrometers or more and 5.5 micrometers or less, Most preferably, they are 2.5 micrometers or more and 5 micrometers or less. By using conductive particles with an average particle size in the above range, the variation in the electrode height of the IC chip and the circuit board and the variation in the parallelism at the time of connection are absorbed, and at the same time, the dielectric breakdown due to the particle retention between adjacent electrodes is suppressed. can do.
The standard deviation of the particle size of the conductive particles is preferably as small as possible, preferably 50% or less of the average particle size, more preferably 20% or less, still more preferably 10% or less, and particularly preferably 5% or less. The particle size of the conductive particles can be measured using a Coulter counter.

The content of the conductive particles is preferably 0.1% by mass or more and 30% by mass or less, more preferably 0.13% by mass or more and 25% by mass or less, and still more preferably 0% with respect to the anisotropic conductive adhesive film of the present invention. 15% by mass or more and 20% by mass or less, more preferably 0.2% by mass or more and 15% by mass or less, and particularly preferably 0.25% by mass or more and 10% by mass or less. In the region where the content of the conductive particles is 0.1% by mass or more and 30% by mass or less, it is easy to achieve both conductivity between the opposing electrodes and insulation between the adjacent electrodes.
The binder resin used in the present invention contains one or more kinds of resins selected from thermosetting resins, thermoplastic resins, photocurable resins, and electron beam curable resins. Examples of these resins include epoxy resins, phenol resins, silicone resins, urethane resins, acrylic resins, polyimide resins, phenoxy resins, polyvinyl butyral resins, SBR, SBS, NBR, polyether sulfone resins, polyether terephthalate resins, polyphenylenes. Sulfide resin, polyamide resin, polyether oxide resin, polyacetal resin, polystyrene resin, polyethylene resin, polyisobutylene resin, alkylphenol resin, styrene butadiene resin, carboxyl-modified nitrile resin, polyphenylene ether resin, polycarbonate resin, polyether ketone resin, those Modified resin is mentioned. In particular, when long-term reliability after connection is required, it is preferable to contain an epoxy resin.

  Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, tetramethylbisphenol A type epoxy resin, biphenol type epoxy resin, naphthalene type epoxy resin, fluorene type epoxy resin, and phenol novolac. Type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolak type epoxy resin, aliphatic ether type epoxy resin, etc. glycidyl ether type epoxy resin, glycidyl ether ester type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, Hydantoin type epoxy resins, alicyclic epoxides, and the like. These epoxy resins may be halogenated or hydrogenated. Tan modified, rubber-modified, may be a modified epoxy resin such as silicone-modified.

  When an epoxy resin is contained in the binder resin, it is preferable to contain a curing agent for the epoxy resin. The curing agent for the epoxy resin is preferably a latent curing agent from the viewpoint of storage stability. As the latent curing agent, curing agents such as boron compounds, hydrazides, tertiary amines, imidazoles, dicyandiamides, inorganic acids, carboxylic acid anhydrides, thiols, isocyanates, boron complex salts and derivatives thereof are preferable. Among latent curing agents, microcapsule type curing agents are preferred. The microcapsule type curing agent is the one that stabilizes the surface of the curing agent for epoxy resin with a resin film, etc., the resin film is destroyed by the temperature and pressure at the time of connection work, the curing agent diffuses outside the microcapsule, Reacts with epoxy resin. Among the microcapsule type latent curing agents, a latent curing agent obtained by microencapsulating an adduct type curing agent such as an amine adduct or an imidazole adduct is preferable because of excellent balance between stability and curability. Generally these hardening | curing agents for epoxy resins are used in the quantity of 0-100 mass parts with respect to 100 mass parts of epoxy resins.

The binder resin used in the present invention has a property of low fluidity under connection conditions in order to prevent the conductive particles from moving at the time of connection and reducing the number of conductive particles captured between the connection electrodes. In addition, it is preferable to contain a phenoxy resin in consideration of long-term connection reliability.
Examples of the phenoxy resin include bisphenol A type phenoxy resin, bisphenol F type phenoxy resin, bisphenol A bisphenol F mixed type phenoxy resin, bisphenol A bisphenol S mixed type phenoxy resin, fluorene ring-containing phenoxy resin, caprolactone-modified bisphenol A type phenoxy resin, and the like. Illustrated. The weight average molecular weight of the phenoxy resin is preferably 20,000 or more and less than 100,000.

As the binder resin used in the present invention, it is preferable to use a phenoxy resin and an epoxy resin in combination. In that case, the amount of the phenoxy resin used is preferably 50% by mass or more based on the whole binder resin, more preferably. 55 mass% or more and 95 mass% or less, More preferably, they are 60 mass% or more and 90 mass% or less.
The binder resin can further contain insulating particles, fillers, softeners, accelerators, anti-aging agents, colorants, flame retardants, thixotropic agents, coupling agents, and the like. When the insulating particles and the filler are contained, the maximum diameter is preferably less than the average particle diameter of the conductive particles. As the coupling agent, ketimine group, vinyl group, acrylic group, amino group, epoxy group, and isocyanate group-containing silane coupling agent are preferable from the viewpoint of improvement in adhesiveness.

  When mixing each component of binder resin, a solvent can be used as needed. Examples of the solvent include methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, ethyl acetate, butyl acetate, ethylene glycol monoalkyl ether acetate, propylene glycol monoalkyl ether acetate, and the like.

The binder resin can be produced, for example, by mixing each component in a solvent to prepare a coating solution, coating the substrate by applicator coating, etc., and volatilizing the solvent in an oven.
When the binder resin contains a thermosetting resin and a microcapsule-type curing agent, it is preferable to heat while stretching in the elastic region of the substrate when the solvent is volatilized.
Since the binder resin has a function of suppressing the flow of the conductive particles at the time of connection, it needs to have low fluidity under the connection condition, and the melt viscosity at 180 ° C. (hereinafter also referred to as “180 ° C. melt viscosity”). It is preferably 50 Pa · s or more, more preferably 65 Pa · s or more and 20,000 Pa · s or less, and still more preferably 80 Pa · s or more and 10,000 Pa · s or less. If the melt viscosity becomes too high, a high temperature is required when embedding the conductive particles in the binder layer, and the manufacturing difficulty level increases.
In addition, when binder resin is a thermosetting resin, the melt viscosity points out the melt viscosity in the state which removed the hardening | curing agent from binder resin, or the state which has not mix | blended the hardening | curing agent.
The film thickness of the binder resin is preferably equal to or less than the average particle size of the conductive particles, more preferably 10% to 200%, more preferably 20% to 170% of the average particle size of the conductive particles. Particularly preferably, it is 25% or more and 140% or less.
The film thickness of the binder resin is preferably less than the average particle diameter of the conductive particles because it is easy to obtain a low connection resistance. In that case, it is low that the conductive particles are substantially exposed above and below the film. It is further preferable in obtaining.

The insulating adhesive used in the present invention contains a thermosetting resin, a microcapsule type curing agent, and a film-forming polymer.
As the thermosetting resin, a resin that reacts with the microcapsule-type curing agent by heating to crosslink is used. As such a thermosetting resin, for example, an epoxy resin, a phenol resin, an acrylate, a urethane resin, or the like is used. For each thermosetting resin, a suitable microcapsule type curing agent is used. For example, in the case of an acrylate having a reactive double bond at the molecular end, the microcapsule type curing agent can generate radicals by heating. A microcapsule-type curing agent or the like in which the periphery of a curing agent such as peroxide is coated with a capsule film is used.
In the present invention, it is preferable to use an epoxy resin as the thermosetting resin because of high connection reliability.

  Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, tetramethylbisphenol A type epoxy resin, biphenol type epoxy resin, naphthalene type epoxy resin, resorcin type epoxy resin, and fluorene type. Epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolak type epoxy resin, glycidyl ether type epoxy resin such as aliphatic ether type epoxy resin, glycidyl ether ester type epoxy resin, glycidyl ester type epoxy resin, glycidyl There are amine type epoxy resins, hydantoin type epoxy resins, alicyclic epoxides, etc., and these epoxy resins are urethane modified, rubber modified, It may be epoxy resin modified corn modified like. A glycidyl ether type epoxy resin is preferable, and a naphthalene type epoxy resin, a bisphenol A type epoxy resin, and a bisphenol F type epoxy resin are more preferable.

Microcapsule type curing agents include boron compounds, hydrazides, amines, imidazoles, dicyandiamide, carboxylic acid anhydrides, thiols, isocyanate compounds, boron complex salts, urea compounds, melamine compounds, and derivatives thereof. Can be used. When the thermosetting resin is an epoxy resin, an adduct-type curing agent such as an amine adduct or an imidazole adduct is preferable because the balance between stability and curability is excellent. Adduct type curing agents are obtained by reaction of amines and imidazoles with epoxy resins, isocyanate compounds, urea compounds and the like. The microcapsule-type curing agent is the one that is stabilized by covering the surface of the curing agent with a capsule film. The capsule film is destroyed by the temperature and pressure at the time of connection work, the curing agent diffuses outside the microcapsule, and is thermally cured. Reacts with functional resin.
As the capsule membrane, a polymer compound is preferable because it has a high balance between stability at room temperature and expression of activity by low-temperature heating, that is, high potential. Examples of the polymer compound used as the capsule membrane include polymer compounds obtained from polyurethane compounds, polyurethane urea compounds, polyurea compounds, polyvinyl compounds, melamine compounds, epoxy resins, and phenol resins.

The microcapsule type curing agent preferably has a structure in which the surface of a fine powdery curing agent is covered with a capsule film, and the average particle size is preferably 0.2 μm or more and 8 μm or less. When the average particle size is less than 0.2 μm, the ratio of the capsule film to the curing agent increases, and the efficiency as the curing agent decreases. On the other hand, when the average particle diameter exceeds 8 μm, a non-uniform cured product tends to be obtained. The average particle size of the microcapsule type curing agent is more preferably 0.5 μm or more and 6 μm or less because secondary aggregation or sedimentation is unlikely to occur when dispersed in the coating liquid, and more preferably 1 μm or more and 4 μm or less. However, since generation | occurrence | production of the surface foreign material of an anisotropic conductive adhesive film is few, it is further more preferable.
Examples of the method for measuring the average particle size of the microcapsule type curing agent include a method using a Coulter counter.

  The activation temperature of the microcapsule-type curing agent is a factor that greatly affects the curability of the anisotropic conductive adhesive film, and the lower activation temperature is preferable in order to exhibit performance in a short time at a low temperature. On the other hand, in order to prevent the thermosetting resin and the microcapsule-type curing agent from reacting during the production of the anisotropic conductive adhesive film, the heating temperature during the formation of the anisotropic conductive adhesive film is the same as that of the microcapsule-type curing material. It is preferable that the temperature is lower than the activation temperature. The activation temperature of the microcapsule-type curing material is preferably equal to or higher than the temperature at which the solvent can be sufficiently volatilized in order to ensure storage stability. The activation temperature of the microcapsule type curing agent is preferably 60 ° C. or higher and 100 ° C. or lower, more preferably 70 ° C. or higher and 90 ° C. or lower.

  In the present specification, the “activation temperature of the microcapsule-type curing agent” means a temperature at which the gel time of a composition in which a microcapsule-type curing agent and a thermosetting resin are mixed at a mass ratio of 1: 2 is 5 minutes. For example, if the gel time at 70 ° C. exceeds 5 minutes and the gel time at 80 ° C. is less than 5 minutes, the activation temperature is higher than 70 ° C. and lower than 80 ° C. In addition, the thermosetting resin used here is a thermosetting resin used for an insulating adhesive, and it is necessary to use the thermosetting resin in the insulating adhesive from the viewpoint of curability. There is.

  In order to obtain a high curing rate of the thermosetting resin, the microcapsule-type curing agent is preferably used at 5 to 60 parts by mass, more preferably 10 to 50 parts by mass with respect to 100 parts by mass of the thermosetting resin. More preferably, it is 20-40 mass parts, and this can suppress the water absorption rate of hardened | cured material low.

  The film-forming polymer used for the insulating adhesive includes phenoxy resin, polyvinyl butyral, polyester resin, polyurethane resin, polyimide resin, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, polyvinyl acetate resin. , Nylon, styrene-isoprene copolymer, and polymethyl methacrylate resin. Since the anisotropic conductive adhesive film is normally in the form of a film, the glass transition temperature of the film-forming polymer needs to be room temperature or higher, preferably the glass transition temperature is 50 ° C. or higher, more preferably It is 60 degreeC or more, More preferably, it is 70 degreeC or more, Thereby, the blocking property of an anisotropically conductive adhesive film can be suppressed largely. The weight average molecular weight of the film-forming polymer is preferably 5,000 or more, more preferably 10,000 or more and 800,000 or less, and still more preferably 20,000 or more and 500,000 or less. Thereby, it exists easily in an insulating adhesive agent, and when it is set as the cured | curing material of an anisotropically conductive adhesive film, strong mechanical strength is expressed.

When an epoxy resin is used as the thermosetting resin, a phenoxy resin having high compatibility with the epoxy resin is preferable as the film-forming polymer. The phenoxy resin used here includes bisphenol A type phenoxy resin, bisphenol F type phenoxy resin, bisphenol A bisphenol F mixed type phenoxy resin, bisphenol A bisphenol S mixed type phenoxy resin, fluorene ring-containing phenoxy resin, caprolactone modified bisphenol A type. Examples include phenoxy resin. The content of the film-forming polymer is preferably 10 to 200% by mass with respect to the thermosetting resin.
Insulating adhesives are used to suppress degradation of adhesiveness and connection reliability due to thermal stress during curing of anisotropic conductive adhesive films and in usage environments, that is, stress due to differences in linear expansion coefficient from the adherend. It is preferable to contain an insulating filler. Examples of the insulating filler include powders such as fused silica, crystalline silica, calcium silicate, alumina, calcium carbonate, and titanium oxide. The average particle diameter of the insulating filler can be measured using a Coulter counter. The average particle size of the insulating filler is preferably 0.01 μm or more in order to sufficiently exhibit the effect of suppressing the decrease in connection reliability due to thermal stress, and is 5 μm or less in order to keep the electrical resistance between the connection terminals low. It is preferable that the particle diameter is smaller than that of the conductive particles. The average particle size of the insulating filler is more preferably 0.05 μm to 3 μm, and still more preferably 0.1 μm to 2 μm. Thereby, aggregation and sedimentation can be suppressed in the coating solution.

The amount of the insulating filler added to the thermosetting resin is sufficient to exert the effect of suppressing the decrease in connection reliability due to thermal stress, and at the same time to maintain high mechanical strength as a cured product of the anisotropic conductive adhesive film. On the other hand, it is preferably used in an amount of 5 to 200% by mass, more preferably 20 to 150% by mass, and still more preferably 30 to 120% by mass.
For insulating adhesives, polyester resin, acrylic rubber, SBR, NBR, silicone resin, polyvinyl butyral resin, polyurethane resin, polyacetal resin, urea resin, xylene resin for the purpose of imparting adhesiveness and stress relaxation during curing It is preferable to contain elastic polymers such as rubbers and elastomers containing functional groups such as carboxyl group, hydroxyl group, vinyl group and amino group. These elastic polymers preferably have a molecular weight of 10,000 to 3,000,000. The content of the elastic polymer component is preferably 2 to 80% by mass with respect to the thermosetting resin.

The insulating adhesive may further contain a softener, an accelerator, an anti-aging agent, a colorant, a flame retardant, a thixotropic agent, and the like. It is preferable to contain a coupling agent from an adhesive viewpoint. As the coupling agent, a silane coupling agent containing a ketimine group, a vinyl group, an acrylic group, an amino group, an epoxy group, or an isocyanate group is preferable from the viewpoint of improving adhesiveness.
Since the insulating adhesive has a function of flowing at the time of connection and sealing the connection region, it needs to have high fluidity under the connection conditions. The relative value of the high fluidity with the fluidity of the binder resin is important. In the present invention, the 180 ° C. melt viscosity of the insulating adhesive must be lower than the 180 ° C. melt viscosity of the binder resin. . The melt viscosity of the insulating adhesive is preferably 50% or less of the melt viscosity of the binder resin, more preferably 25% or less, still more preferably 15% or less, and particularly preferably 10% or less. It is.
The preferable range of the 180 ° C. melt viscosity of the insulating adhesive is 1 Pa · s or more and less than 100 Pa · s, more preferably 2 Pa · s or more and 50 Pa · s or less, and further preferably 4 Pa · s or more and 30 Pa · s or less. . If the melt viscosity is too high, a high pressure is required at the time of connection. On the other hand, if the melt viscosity is low, it is necessary to store at a low temperature in order to suppress deformation before use.
In addition, when the insulating adhesive is a thermosetting resin, the melt viscosity indicates the melt viscosity in a state where the curing agent is removed from the insulating adhesive or in a state where the curing agent is not blended.

The insulating adhesive may be formed only on one side of the conductive layer or on both sides. When laminating on both surfaces of the conductive layer, the insulating adhesive on each surface may be the same or different. Different ones can be formulated according to the connected member, while the need to prepare two types of formulations arises.
When the insulating adhesive is formed on both sides of the conductive layer, it is preferable that the conductive particles do not enter the inside from the surface on one side of the anisotropic conductive adhesive film in order to suppress the movement of the conductive particles due to the pressure at the time of connection. The center position of the conductive particles is preferably located at 2.0 times or less, more preferably 1.5 times or less, more preferably 1 from the surface of one side of the anisotropic conductive adhesive film. 0.0 times or less, particularly preferably 0.8 times or less. On the other hand, at 0.5 times or less, the conductive particles are exposed from the anisotropic conductive adhesive film, and when the amount of exposure increases, the sticking property of the anisotropic conductive adhesive film decreases, or the conductive particles Is preferably 0.1 times or more, more preferably 0.2 times or more, and still more preferably 0.3 times or more.

The total thickness of the conductive layer is preferably 4 μm to 50 μm, more preferably 5 μm to 30 μm, still more preferably 6 μm to 25 μm, and particularly preferably 7 μm to 22 μm.
The total film thickness of the insulating adhesive is preferably 2 to 100 times the film thickness of the binder resin, more preferably 3 to 75 times, still more preferably 4 to 50 times, especially Preferably they are 5 times or more and 30 times or less.

  In the present invention, in order to obtain an insulating adhesive in which each component in the insulating adhesive is uniform and has little film thickness variation, the insulating adhesive is dissolved or dispersed in a solvent to obtain a coating liquid. In order for the insulating adhesive to be uniformly dissolved or dispersed in the solvent, the solvent used in the present invention is required to have high solubility or dispersibility of each component of the insulating adhesive. Further, in order to ensure the stability of the insulating adhesive, the solvent is required not to dissolve the capsule film of the microcapsule type curing agent. Examples of such a solvent include methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, ethyl acetate, butyl acetate, ethylene glycol monoalkyl ether acetate, propylene glycol monoalkyl ether acetate and the like. A plurality of solvents can be used in combination.

The amount of the solvent used is determined so that the coating solution has a viscosity suitable for coating. The viscosity of the coating liquid is preferably 100 mPa · s or more and 20000 mPa · s or less, more preferably 300 mPa · s or more and 15000 mPa · s or less, and still more preferably 400 mPa · s or more and 10,000 mPa · s or less. .
The water content in the coating liquid is preferably 0.5% by mass or more from the viewpoint of productivity, while it is 10% by mass or less in order to keep the stability of the microcapsule type curing agent high. Preferably, 5 mass% or less is more preferable. In the present invention, the coating liquid is applied onto the peelable substrate. Examples of the peelable substrate include films such as polyesters such as polyethylene, polypropylene, polystyrene, PET, and PEN, nylon, vinyl chloride, and polyvinyl alcohol. From the viewpoints of thickness stability, solvent resistance, and economy, the peelable substrate is preferably polypropylene, PET, or the like. The peelable substrate is preferably subjected to a surface treatment such as fluorine treatment, silicone treatment, alkyd treatment or the like. The thickness of the peelable substrate is preferably 30 μm or more and 100 μm or less because of excellent handling properties and thickness stability during the coating operation.

The elastic region of the peelable substrate means a strain region within the yield point in the stress-strain curve (hereinafter also referred to as “SS curve”) of the peelable substrate. When there is no yield point, in the present invention, the inflection point at which the SS curve deviates from the linear region is taken as the yield point. The yield stress at 70 ° C. of the peelable substrate is preferably higher because of the wide range of stretching conditions, preferably 1 MPa or more, more preferably 2 MPa or more, and further preferably 3 MPa or more.
The 70 ° C. Young's modulus of the peelable substrate is preferably 1 MPa or more and 10 GPa or less, more preferably 3 MPa or more and 5 GPa or less, and further preferably 5 MPa or more and 3 GPa, in order to achieve both the rigidity of the stretching apparatus and the stretching stability. It is as follows.

Hereinafter, the manufacturing method of the anisotropically conductive adhesive film of this invention is demonstrated.
The production of the insulating adhesive of the present invention includes a step of preparing a coating liquid, a step of applying the coating liquid on a peelable substrate, and a film forming step of forming a film by heating.
In the step of preparing the coating liquid, each component of the insulating adhesive is dissolved or uniformly dispersed in the solvent. Each component of the insulating adhesive may be mixed at the same time. However, after the film-forming polymer is first dissolved in a solvent and then the microcapsule-type curing agent is uniformly dispersed, the film-forming polymer remains undissolved. An insulating adhesive having a small amount and high storage stability is preferable. The step of producing the coating liquid is preferably performed at 10 ° C. or higher and 100 ° C. or lower.

  The step of applying the coating liquid onto the peelable substrate can be performed by a method using a bar coater, a blade coater, a roll coater, a die coater, a gravure coater or the like.

In the film forming step, the peelable substrate coated with the coating liquid is heated while being stretched in the elastic region of the peelable substrate to volatilize the solvent to form a film.
Examples of the heating method include a method of supplying hot air into the dryer, a method of irradiating heat rays such as infrared rays, a method of supplying heat from the peelable substrate side by a heating roll, and the like. A method using hot air is preferred because the volatilized solvent easily escapes from the system and the solvent volatilization efficiency is high.
The heating temperature is preferably high in order to increase the volatilization efficiency of the solvent and form a film in a short time, and in order not to react the thermosetting resin with the microcapsule type curing agent, It is preferable that it is below the activation temperature. As heating temperature of a film forming process, 50 degreeC or more and 90 degrees C or less are preferable, More preferably, they are 60 degreeC or more and 80 degrees C or less.

  The heating time is preferably 3 minutes or more and 20 minutes or less. From the point of removing the remaining solvent and improving the storage stability of the insulating adhesive, 3 minutes or more is preferable. On the other hand, the reaction between the thermosetting resin and the microcapsule type curing agent is prevented in the film forming process, and at the same time From the viewpoint of improving the storage stability of the insulating adhesive, it is preferably within 20 minutes, more preferably within 5 minutes to 15 minutes.

  In the film forming step, the peelable substrate coated with the coating solution is stretched. In the film forming process, the solvent is volatilized by heating to near the activation temperature of the microcapsule type curing agent. At this time, if an external stimulus is applied to promote the activation of the microcapsule type curing agent, The reaction between the curable resin and the microcapsule type curing agent starts, and the storage stability of the insulating adhesive is lowered. Examples of the external stimulus include impact caused by contact between the microcapsule type curing agent and the microcapsule type curing agent and the insulating filler caused by the vibration of the film by hot air used in the film forming process, contact with moisture, and the like. . In this invention, the peelable base material which apply | coated the coating liquid in the film forming process is extended | stretched. By suppressing the vibration of the film due to hot air by the tension at the time of stretching, that is, by reducing the external stimulus, it is possible to avoid a decrease in the storage stability of the insulating adhesive. Furthermore, by stretching within the elastic region of the peelable substrate, the volatilization efficiency of the solvent is enhanced, and as a result that moisture that can be an external stimulus is rapidly volatilized out of the system, storage of the insulating adhesive is performed. A decrease in stability is suppressed.

The tension applied at the time of stretching needs to be a deformation amount of the peelable substrate in the elastic region, and is preferably 0.3 MPa or more and 200 MPa or less per peelable substrate cross-sectional area. In order to obtain the effect of keeping the storage stability high, the tension is preferably 0.3 MPa or more. On the other hand, from the viewpoint of suppressing film thickness unevenness of the obtained insulating adhesive, it is preferably 200 MPa or less. . The tension is more preferably 0.5 MPa or more and 100 MPa or less per cross-sectional area, and more preferably 1 MPa or more and 50 MPa or less, whereby the surface smoothness is high, and the sticking property when sticking to the adherend is excellent. Insulating adhesive can be obtained.
Stretching of the peelable substrate in the film forming process may be performed in one direction or in two directions. The elongation percentage of the peelable substrate in stretching is preferably 0.1% or more and 20% or less. In order to obtain the effect of keeping the storage stability high, the elongation is preferably 0.1% or more, while it is preferably 20% or less from the viewpoint of suppression of film thickness unevenness and sticking property, More preferably, it is 0.2% or more and 15% or less.

The method for producing the conductive layer of the present invention is as follows, for example.
First, an arrayed sheet of conductive particles in which conductive particles arranged in a single layer are fixed on a sheet with an adhesive is manufactured. In order to manufacture the array sheet, for example, an adhesive is preferably applied on a stretchable sheet so that the film thickness is equal to or less than the average particle diameter of the conductive particles, and the conductive particles are filled thereon. Thereafter, the conductive particles that have not reached the pressure-sensitive adhesive layer are removed by air blowing or the like, thereby forming a single conductive particle layer in which the conductive particles are densely packed. If necessary, the conductive particles arranged in a single layer are embedded in the adhesive. The filling rate defined by the ratio of the projected area of the conductive particles to the total area at this time is preferably 60% or more and 90% or less, more preferably 65% or more and 88% or less, and further preferably 68% or more and 85%. It is as follows. The filling factor greatly affects the coefficient of variation of the distance between the centers of the conductive particles, which is an important factor in the present invention.

Next, by stretching the sheet on which the obtained conductive particles are fixed at a desired draw ratio, the individual conductive particles are arranged to have a desired center-to-center distance with a coefficient of variation necessary for the present invention. An array sheet of conductive particles obtained is obtained.
Examples of the stretchable sheet include polyesters such as polyethylene, polypropylene, polystyrene, PET, and PEN, and shio such as nylon, vinyl chloride, and polyvinyl alcohol. Examples of the adhesive include urethane resin, acrylic resin, urea resin, melamine resin, phenol resin, vinyl acetate, chloroprene and the like.
Stretching is so-called biaxial stretching in which both longitudinal stretching and lateral stretching are performed, and can be performed by a known method. For example, there are a method of pulling by sandwiching two or four sides of the film with a clip or the like, a method of stretching by sandwiching between two or more rolls and changing the rotation speed of the roll. The stretching may be simultaneous biaxial stretching in which the machine direction and the transverse direction are stretched simultaneously, or may be sequential biaxial stretching in which the other is stretched after stretching in one direction. Simultaneous biaxial stretching is preferred because it is difficult to cause disorder in the arrangement of the conductive particles during stretching. In order to perform stretching with high accuracy, it is preferable to soften a stretchable film. Depending on the stretchable sheet used, for example, it is preferable to perform stretching at 70 ° C. or more and 250 ° C. or less, and more preferably. Is 75 ° C. or higher and 200 ° C. or lower, more preferably 80 ° C. or higher and 160 ° C. or lower, and particularly preferably 85 ° C. or higher and lower than 145 ° C. If the stretching temperature is too high, the adhesive strength of the pressure-sensitive adhesive is reduced, the arrangement of the conductive particles is disturbed, and the coefficient of variation in the distance between the centers of the conductive particles is increased.

Next, a binder resin is stacked on the conductive particle side of the array sheet, and the conductive particles are embedded in the binder resin. Examples of the embedding method include a method in which a film-like binder resin is laminated on the conductive particle side of the array sheet and laminated, and the conductive particles are embedded using a hot roll or the like. The stretchable sheet and the adhesive of the array sheet are peeled from the conductive particles embedded in the binder.
In the present invention, the conductive particles are preferably embedded at a temperature as low as possible. In particular, when the binder resin or the insulating adhesive is a thermosetting resin containing a latent curing agent, when the binder resin or the insulating adhesive is embedded at a high temperature, low temperature storage is required to suppress the progress of the curing reaction. On the other hand, if the temperature is low, embedding becomes difficult because the viscosity of the binder resin is high. Therefore, the embedding temperature of the conductive particles is preferably 35 ° C. or higher and 120 ° C. or lower, more preferably 40 ° C. or higher and 100 ° C. or lower, and further preferably 45 ° C. or higher and 80 ° C. or lower.

When embedding the conductive particles in the binder resin, after peeling the stretchable sheet and the adhesive from the binder resin in which the conductive particles are embedded, the film having a high elastic modulus is stacked on the conductive particle side, and further using a heat roll or the like. It is preferable to embed the conductive particles in the binder resin. Examples of the film having a high elastic modulus include an aramid film.
When the conductive particles are not sufficiently embedded in the binder resin, the conductive particles are missing from the binder resin before use, causing connection failure.
An anisotropic conductive adhesive film is obtained by laminating the conductive layer and the insulating adhesive using a hot roll or the like.

The binder resin may be bonded with an insulating adhesive on the surface opposite to the surface on which the conductive particles are embedded, or after the conductive particles are embedded on the surface of the binder resin opposite to the surface on which the conductive particles are embedded. An insulating adhesive may be bonded by lamination or the like. If necessary, another insulating adhesive is laminated on the surface of the binder resin in which the conductive particles are embedded.
The thickness of the anisotropic conductive adhesive film obtained by the method of the present invention is preferably 5 μm or more and 50 μm or less. From the viewpoint of suppressing surface abnormalities, the film thickness is preferably 5 μm or more. On the other hand, from the viewpoint of storage stability of the anisotropic conductive adhesive film, it is preferably 50 μm or less, more preferably 10 μm or more and 30 μm or less.

The amount of the solvent remaining in the anisotropic conductive adhesive film obtained by the method of the present invention can be a factor that lowers storage stability, so the smaller the amount, the better. The residual solvent is preferably 1% by mass or less, more preferably 0.7% by mass or less, and still more preferably 0.5% by mass or less.
The anisotropic conductive adhesive film obtained by the method of the present invention may be slit to a desired width and wound up in a reel shape.

Hereinafter, the present invention will be described in more detail with reference to examples.
<Melt viscosity measurement>
The measurement was carried out at 180 ° C. using a 20 mm diameter cone (PP20H) using a RAKEStress 600 Thermo manufactured by HAAKE.

<Measurement of moisture>
The measurement was performed using a Karl Fischer moisture meter CA-100 manufactured by Dia Instruments.

<Measurement of gel time>
Using a Clastometer V type manufactured by TS Engineering Co., Ltd., it was determined according to JIS K6300.

<Measurement of Young's modulus and yield stress>
Using a universal material testing machine 5581 manufactured by INS (registered trademark) TRON, the test speed was 50 mm / min, the distance between chucks was 50 mm, and the test piece width was 25 mm in accordance with JIS K7161.

<Film thickness measurement>
It measured using Nikon Digimicro MH-15M, and made the average value of 25 measurement number the film thickness.

<Connection resistance measurement>
The connection resistance between the connection terminals was measured by a four-terminal method using a 3541 REISTANCE HiTESTER manufactured by Hioki Electric Co., Ltd.

[Example 1]
Phenoxy resin (InChem, trade name: PKHC) 100 parts by mass, Bisphenol A type liquid epoxy resin (Asahi Kasei Chemicals, trade name: AER2603) 60 parts by mass, 2-phenylimidazole (Shikoku Chemicals, trade name) : 2PZ) 5 parts by mass, silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name KBM-403) 0.25 part by mass and methyl ethyl ketone 300 parts by mass were mixed to obtain a binder varnish. The binder varnish was applied onto a release sheet made of 50 μm PET film using a blade coater, and the solvent was removed by drying to obtain a film-like binder resin A having a thickness of 4 μm. Separately, the melt viscosity of a binder resin prepared by blending without containing only 2-phenylimidazole was measured, and the 180 ° C. melt viscosity of the binder resin A was 78.4 Pa · s.

  An acrylic polymer diluted with ethyl acetate to a resin content of 5% by mass using a blade coater was applied onto a 100 μm unstretched copolymerized polypropylene film and dried at 80 ° C. for 10 minutes to form an adhesive layer having a thickness of 2 μm. The acrylic polymer used here was 62 parts by mass of methyl acrylate, 30.6 parts by mass of 2-ethylhexyl acrylate, and 7 parts by mass of 2-hydroxyethyl acrylate in 233 parts by mass of ethyl acetate. The weight average molecular weight obtained by polymerizing 0.2 parts by mass of nitrile at 65 ° C. for 8 hours in a nitrogen gas stream is 950,000. The weight average molecular weight was measured by gel permeation chromatography (GPC).

  On this pressure-sensitive adhesive, conductive particles having an average particle diameter of 3 μm were filled on one side, and conductive particles that did not reach the pressure-sensitive adhesive were eliminated by air blowing. As a result, a single-layer conductive particle layer having a filling rate of 82% was formed. Here, the conductive particles have a core of divinylbenzene resin, a nickel layer of 0.07 μm is formed on the surface layer by electroless plating, and a gold layer of 0.04 μm is further formed by electroplating. The one with a ratio of 0.95 and a standard deviation of particle diameter of 0.2 μm was used.

  Next, the conductive film is fixed to the polypropylene film with the adhesive using a test biaxial stretching device, and stretched to 135 times at a rate of 10% / second in both longitudinal and lateral directions at a rate of 10% / second. The array sheet A was obtained by cooling to room temperature.

100 parts by mass of phenoxy resin (InChem, product name: PKHC, the same shall apply hereinafter), bisphenol A type liquid epoxy resin (Asahi Kasei Chemicals Co., Ltd., product name: AER2603, the same shall apply hereinafter), silane coupling agent (Shin-Etsu) Made by Kagaku Kogyo Co., Ltd., trade name: KBM-403, the same applies hereinafter) 1.0 part by mass is dissolved in 400 parts by mass of ethyl acetate, and as a curing agent, the mass ratio of microcapsule type curing agent and liquid epoxy resin is 1: 2. 100 parts by mass of a mixture (made by Asahi Kasei Chemicals Co., Ltd., trade name: NovaCure HX-3932HP, activation temperature 90 ° C., the same shall apply hereinafter) is mixed, and further, spherical silica particles having an average particle diameter of 1 μm (specific gravity 1.82) 20 masses. Parts were dispersed substantially uniformly to obtain a coating liquid A.
The raw materials other than ethyl acetate used here were those that were vacuum dried at 50 ° C. for 24 hours. The ethyl acetate used was one obtained by immersing Molecular Sieves 3A for 1 week and dehydrating it. The water content in the coating liquid A was 9.6% by mass with respect to the microcapsule type curing agent.

  An 80 μm-thick unstretched copolymerized polypropylene film (with Young's modulus and yield stress at a film forming temperature of 70 ° C. and a yield stress of 27 MPa and 5 MPa, respectively) prepared as a peelable substrate was prepared. The coating liquid A was applied to the side using a blade coater. The coated film obtained here was stretched in a uniaxial direction with a tension at which the elongation rate of the peelable substrate at the film-forming temperature was 15% using a manual stretching machine, and 70 with a hot-air circulating dryer. C. (film formation temperature) was heated for 10 minutes to volatilize the solvent to form a film, and an insulating adhesive A was obtained. The film thickness of the insulating adhesive A was 25 μm. Insulating adhesive B having a different film thickness was obtained in the same manner as described above. The film thickness of the insulating adhesive B was 1 μm.

  The binder resin A was overlapped on the conductive particle side of the array sheet A and laminated under the conditions of 55 ° C. and 0.3 MPa to obtain a conductive layer A. After peeling off the release sheet that had been laminated to the binder resin opposite to the surface where the conductive particles were embedded, the insulating adhesive A was superimposed on the surface of the binder resin opposite to the surface where the conductive particles were embedded, and lamination was performed under the same conditions. went. Next, the polypropylene film and the adhesive of the array sheet A were peeled from the binder resin surface in which the conductive particles were embedded. A part of the sample was sampled, and the embedding depth of the conductive particles was observed using a laser microscope (manufactured by Keyence Corporation, trade name VK-9500, hereinafter the same). As a result, the conductive particles were exposed from the 2.25 μm binder resin. In the middle of handling, the absence of particles was observed.

  Next, a film obtained by treating a 16 μm aramid film (manufactured by Teijin Ltd., trade name: Aramika, elastic modulus: 15 Gpa) with a release agent on the binder resin surface in which the conductive particles are embedded is superposed at 60 ° C. and 1.0 MPa. After embedding the conductive particles with a heat roll under the conditions, the aramid film was peeled off, and the insulating adhesive B was laminated on the surface thereof under the same conditions as described above to obtain an anisotropic conductive adhesive film A.

When the embedding depth of the conductive particles of the obtained anisotropic conductive adhesive film A was measured, the exposure from the binder resin was an average of 0.1 μm, and the embedding depth was 97% of the average particle diameter of the conductive particles. It was equivalent. Further, the variation in the center height of the conductive particles calculated from the exposure amount was less than 0.5 μm. Furthermore, as a result of observing the anisotropic conductive adhesive film A with a microscope (manufactured by Keyence Corporation, trade name: VHX-100, the same shall apply hereinafter), the conductive particles are arranged in a single layer on the surface layer of the binder resin A. From the image obtained with the microscope, using image processing software (trade name: A image kun, manufactured by Asahi Kasei Co., Ltd., the same applies hereinafter), the average value of the center-to-center distance of the conductive particles and the coefficient of variation thereof were determined. The average value was 8.3 μm and the coefficient of variation was 0.17. As the distance between the centers of the conductive particles, the length of a side of a triangle formed by Deloni triangulation using the center point of each particle was used, and the observation of the conductive particles was performed for particles within 0.06 mm ² .

  Next, a 1.5 mm × 16.1 mm IC chip in which gold bumps of 25 μm × 100 μm are arranged at a pitch of 50 μm, and a chromium wiring (0.3 μm) on an ITO wiring (0.14 μm) having a corresponding connection pitch. Three glass substrates having a thickness of 0.7 mm were prepared, and an anisotropic conductive adhesive film A of 2 mm × 20 mm was attached so as to cover the IC chip connection position of the glass substrate. Next, thermocompression bonding was performed under the conditions of 70 ° C., 0.5 MPa, and 2 seconds to peel the peelable substrate. In all three groups, the peelable substrate could be peeled off, and the sticking property was good. The glass substrate on which the anisotropic conductive adhesive film A is pasted and the IC chip are aligned using a flip chip bonder (FC2000 manufactured by Toray Engineering Co., Ltd.), reaches 180 ° C. after 2 seconds, and then reaches a certain temperature. Under such conditions, 4 MPa and 10 seconds were heated and pressed to connect the IC chip to the glass substrate.

  From the IC chip and the glass substrate, the four-terminal connection resistance could be measured at five locations, and the average value of the connection resistance at 3 sets × 5 locations (a total of 15 locations) was 11.3Ω, which was stably connected. Furthermore, after leaving for 1,000 hours in an environment of 85 ° C. and a relative humidity of 85%, the connection resistance was measured in the same manner. As a result, the average value of the connection resistance was 15.1Ω, and it had excellent connection reliability. It was.

Comb electrodes having 20 pairs of combs were formed from the IC chip and the glass substrate, and the insulation resistance was measured. The insulation resistance of the comb-shaped electrode was 10 ⁹ Ω or more, and no short circuit occurred between adjacent electrodes. Furthermore, after leaving for 1,000 hours in an environment of 85 ° C. and a relative humidity of 85%, the connection resistance was measured in the same manner. As a result, the insulation resistance was 10 ⁹ Ω or more, and excellent connection reliability was obtained.

Next, using the anisotropic conductive adhesive film A stored at 5 ° C. for 6 months, the sticking property and connection resistance measurement, the insulation resistance measurement, and the connection resistance and insulation resistance measurement after 1000 hours were performed as described above. . Adhesiveness is good, connection resistance is 15.4Ω, connection resistance after 1,000 hours is 17.1Ω, insulation connection resistance is 10 ⁹ Ω or more, and insulation connection resistance after 1,000 hours is It was 10 ⁹ Ω or more, and the anisotropic conductive adhesive film A had high storage stability.

[Examples 2 to 7]
An insulating adhesive was prepared in the same manner as in Example 1 with the blending amounts and manufacturing conditions shown in Table 1 below, and the conductive layer A was laminated with the insulating adhesive in an anisotropic manner as in Example 1. A conductive adhesive film was produced. In the same manner as in Example 1, the moisture content of the coating solution for the insulating adhesive, the sticking property of the anisotropic conductive adhesive film, the connection resistance measurement, and the storage stability were evaluated. The results obtained are shown in Table 1 below. In addition, as in Example 1, the insulation resistance measurement and the insulation connection resistance measurement after 1,000 hours were performed, and all were 10 ⁹ Ω or more.

[Comparative Example 1]
An anisotropic conductive adhesive film was prepared in the same manner as in Example 1 with the blending amounts and production conditions shown in Table 1 below, and in the same manner as in Example 1, the water content of the coating solution, the adhesiveness, and the connection resistance Measurement, insulation resistance measurement, and storage stability were evaluated. The results obtained are shown in Table 1 below. In Comparative Example 1, in the film forming step, the peelable substrate to which the coating liquid was applied did not volatilize the solvent while stretching in the elastic region of the peelable substrate (in Table 1, during film formation). The elongation percentage of the substrate is 0%). The anisotropic conductive adhesive film used in Comparative Example 1 had a slightly low sticking property immediately after production and could not be attached to one of the three sheets, but the one that could be attached was capable of stable connection. . However, when the anisotropic conductive adhesive film is stored, the sticking property is lowered, and furthermore, the pasted one has a high connection resistance and cannot be stably connected. The storage stability of the anisotropic conductive adhesive film Was inferior.

[Comparative Example 2]
An anisotropic conductive adhesive film was prepared in the same manner as in Example 1 with the blending amounts and production conditions shown in Table 1 below, and the water content and adhesiveness of the coating liquid were evaluated in the same manner as in Example 1. . The results obtained are shown in Table 1 below. In the insulating adhesive used in Comparative Example 2, since the stretching tension at the time of film formation exceeded the yield stress of the peelable substrate, it was outside the elastic region, and the peeled substrate was partially stretched greatly (in Table 1). The elongation percentage of the base material during film formation was 30%), and the film thickness of the insulating adhesive varied greatly depending on the location. Furthermore, in the evaluation of stickability, wrinkles due to stretching unevenness occurred on the surface of the insulating adhesive, so that the peelable substrate could not be peeled from the insulating adhesive, and the circuit connecting material was not used.

  The present invention is excellent in electrical connection of electrodes having a small area in electrical connection of fine patterns, and is less likely to cause dielectric breakdown (short circuit) between fine wirings, and can be electrically connected to semiconductor chips having different electrode patterns. Connection is possible, long-term reliability can be achieved, both low-temperature short-time curability and storage stability can be achieved, and in addition, it has good adhesiveness to substrates and is suitable for circuit connection applications. Can also be suitably used.

Claims (9)

In a method for producing an anisotropic conductive adhesive film in which a conductive layer made of a binder resin having conductive particles arranged in a single layer on a surface layer and an insulating adhesive laminated on at least one surface of the conductive layer, The coefficient of variation in distance is from 0.05 to 0.5, the 180 ° C. melt viscosity of the insulating adhesive is lower than the 180 ° C. melt viscosity of the binder resin, and the method comprises the following steps:
A step of preparing a coating liquid in which the insulating adhesive containing a thermosetting resin, a microcapsule-type curing agent, and a film-forming polymer is dissolved or dispersed in a solvent;
A step of applying the coating liquid on a peelable substrate;
A film-forming step in which the peelable substrate coated with the coating liquid is heated while being stretched within the elastic region of the peelable substrate to volatilize the solvent,
The manufacturing method of the said anisotropically conductive adhesive film characterized by including.   2. The anisotropic conductivity according to claim 1, wherein an average distance between centers of the conductive particles is 2 μm or more and 20 μm or less, and is 1.5 times or more and 5 times or less with respect to an average particle diameter of the conductive particles. Method for producing an adhesive film.   The method for producing an anisotropic conductive adhesive film according to claim 1, wherein the binder resin has a melt viscosity at 180 ° C. of 50 Pa · s or more.   The method for producing an anisotropic conductive adhesive film according to any one of claims 1 to 3, wherein the thermosetting resin is an epoxy resin. The said microcapsule type hardening | curing agent is a manufacturing method of the anisotropically conductive adhesive film of Claim 4 which has the structure which coat | covered the circumference | surroundings of the hardening | curing agent for epoxy resins with the high molecular compound.
  The method for producing an anisotropic conductive adhesive film according to claim 1, wherein an activation temperature of the microcapsule type curing agent is 60 ° C. or more and 100 ° C. or less.   The anisotropic conductivity according to any one of claims 1 to 6, wherein a moisture content in the coating liquid is 0.5% by mass or more and 10% by mass or less with respect to the microcapsule type curing agent. A method for producing an adhesive film.   The method for producing an anisotropic conductive adhesive film according to claim 1, wherein the conductive particles have an average particle size of 0.5 μm or more and 10 μm or less.   The method for producing an anisotropic conductive adhesive film according to any one of claims 1 to 8, wherein a heating temperature in the film forming step is 50 ° C or higher and 90 ° C or lower.