KR20120099424A - Anisotropic conductive film, connection structure and method of manufacturing the same - Google Patents

Abstract

In the anisotropic conductive adhesive film for anisotropic conductive connection between the terminal of the flexible board and the terminal of the rigid board, the particle diameter of the conductive particles after the anisotropic conductive connection is set to A, and the gap between the terminal of the flexible board and the terminal of the rigid board is B. When it is set as the electroconductive particle, what has a particle diameter of 4 micrometers or more and compressive hardness of 4500 kgf / mm <2> or more is used so that the indentation rate defined by 100 (AB) / A may be 40% or more. Moreover, when the maximum diameter of electroconductive particle is made a and the minimum diameter is b, the sphericity of the electroconductive particle represented by a / b is 5 or less.

Description

Anisotropic conductive adhesive film, bonded structure and manufacturing method therefor {ANISOTROPIC CONDUCTIVE FILM, CONNECTION STRUCTURE AND METHOD OF MANUFACTURING THE SAME}

The present invention provides an anisotropic conductive adhesive film for anisotropic conductive connection between a terminal of a flexible substrate and a terminal of a rigid substrate, a bonded structure in which terminals of a flexible substrate and a rigid substrate are anisotropic conductively connected using the anisotropic conductive adhesive film, and the manufacture thereof It is about a method.

As the said electroconductive particle of the anisotropic conductive adhesive film which electroconductive particle disperse | distributed in the binder resin composition, the surface of the resin core particle | grains so that electroconductive particle itself may deform | transform and the contact area with a terminal may increase by the heat press process at the time of anisotropic conductive connection. It is widely used to form an electroless nickel thin film and to use the electroless gold flash plating thin film as needed (patent document 1).

By the way, using the anisotropic conductive adhesive film containing such electroconductive particle, about the connection structure obtained by carrying out the anisotropic conductive connection of the terminal of a flexible board | substrate and the terminal of a rigid board | substrate, such as a glass substrate, the connection state by an anisotropic conductive adhesive film In order to confirm, observing the indentation which generate | occur | produced in the terminal of a flexible substrate with the electroconductive particle in an anisotropic conductive adhesive film using a microscope etc. from the flexible substrate side is performed (patent document 2).

Japanese Patent Laid-Open No. 9-199206 Japanese Unexamined Patent Publication No. 2008-91843

However, as described in patent document 2, the indentation of a terminal from the flexible substrate side about the connection structure obtained by carrying out the anisotropic conductive connection of the terminal of a flexible board | substrate and the terminal of a rigid board | substrate using the anisotropic conductive adhesive film of patent document 1 When it observed, electroconductive particle was too flexible, electroconductive particle did not fully penetrate into the terminal of a flexible board | substrate, and there existed a problem which does not produce the indentation which can be observed in a terminal. Moreover, when storing under high temperature, high humidity environment, there also existed a problem that connection resistance may increase and connection reliability may fall.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems of the prior art, and with respect to a connection structure obtained by anisotropic conductive connection between a terminal of a flexible substrate and a terminal of a rigid substrate using an anisotropic conductive adhesive film, It is possible to observe the indentation, and to ensure good connection reliability even when stored in a high temperature, high humidity environment.

MEANS TO SOLVE THE PROBLEM The present inventors adjust the magnitude | size of the electroconductive particle, compression hardness, and sphericity to a predetermined range, so that the electroconductive particle of an anisotropic electrically conductive adhesive film can fully be dug into the terminal of a flexible board instead of the terminal of a rigid board | substrate. It has been found that the above-described objects can be attained, thereby completing the present invention.

That is, this invention is an anisotropic conductive adhesive film for anisotropic conductive connection of the terminal of a flexible board | substrate and the terminal of a rigid board | substrate, In an anisotropic conductive adhesive film in which electroconductive particle is disperse | distributed to a binder resin composition, electroconductive particle after anisotropic conductive connection When the particle diameter of A is made A and the gap between the terminal of a flexible board | substrate and the terminal of a rigid board | substrate is B, electroconductive particle is 4 micrometers or more so that the indentation rate defined by 100 (AB) / A will be 40% or more. The sphericity of the electroconductive particle represented by a / b is 5 or less, when it has a particle diameter and the compressive hardness of 4500 kgf / mm <2> or more, and the maximum diameter of electroconductive particle is a and the minimum diameter is b, It is characterized by the above-mentioned. An anisotropic conductive adhesive film is provided.

Moreover, this invention is the terminal of a flexible board | substrate and the terminal of a rigid board | substrate, The connection structure of the terminal of a flexible board | substrate and a rigid board | substrate in the bonded structure which anisotropically conductively connected through the anisotropic conductive adhesive film in which electroconductive particle is disperse | distributed to a binder resin composition is When the electroconductive particle of the anisotropic conductive adhesive film which should be clamped between terminals has a particle diameter of 4 micrometers or more, the compressive hardness of 4500 kgf / mm <2> or more, and makes the maximum diameter a and the minimum diameter b, a The sphericity of the electroconductive particle represented by / b is 5 or less, when the particle diameter of the electroconductive particle after anisotropic conductive connection is set to A, and the gap between the terminal of a flexible board | substrate and the terminal of a rigid board | substrate is 100 (AB) Electroconductive particle penetrates into the terminal of a flexible substrate so that the indentation rate defined by / A may be 40% or more, The connection characterized by the above-mentioned. Provide a structure.

Moreover, this invention is a manufacturing method of the above-mentioned connection structure WHEREIN: The anisotropic conductive adhesive film of this invention is temporarily attached on the terminal of a rigid board | substrate, the anisotropic conductive adhesive film is sandwiched, and the terminal of a rigid board | substrate of a flexible substrate is provided. When a flexible board | substrate is arrange | positioned so that a terminal may correspond, the particle diameter of the electroconductive particle after anisotropic conductive connection shall be set to A, and when the gap between the terminal of a flexible board | substrate and the terminal of a rigid board | substrate shall be B, it will be 100 (AB) / A. An anisotropic conductive connection is provided by heat-pressing an anisotropic conductive adhesive film with a heating bonder from the flexible substrate side so that the defined indentation rate is 40% or more.

In the anisotropic conductive adhesive film of this invention, the particle diameter, compressive hardness, and sphericity of electroconductive particle are respectively limited to the specific range. For this reason, when the particle diameter of the electroconductive particle in the bonded structure after anisotropic conductive connection is set to A, and the gap between the terminal of a flexible board | substrate and the terminal of a rigid board | substrate is set to B, it is press-in defined as 100 (AB) / A. The rate can be 40% or more. Therefore, the indentation of a terminal can be observed from the flexible board side of a bonded structure, and also favorable connection reliability can be ensured even when it preserve | stores in a high temperature, high humidity environment.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing of the indentation rate of electroconductive particle.

The anisotropic conductive adhesive film of the present invention is made of a terminal of a flexible substrate on which copper wiring, aluminum wiring, or the like is formed on a resin film such as polyimide, polyester, polyamide, polysulfone, a glass substrate, a ceramic substrate, or a glass epoxy product. Electroconductive particle is disperse | distributed to a binder resin composition as an anisotropic conductive adhesive film for anisotropically conductively connecting the terminal of the rigid board | substrate with which ITO wiring, copper wiring, aluminum wiring, etc. were formed in rigid substrates, such as a printed wiring board. Here, as a preferable rigid substrate, a glass substrate is mentioned from a transparency point. In addition, a semiconductor chip or the like may be mounted on the flexible substrate or the rigid substrate. In addition, you may give gold plating etc. to the terminal of each board | substrate as needed.

In this invention, as shown in FIG. 1, the particle diameter of the electroconductive particle 1 after anisotropic conductive connection is set to A, the terminal 3 of the rigid board | substrate 2, and the terminal 5 of the flexible board | substrate 4 are shown. When the gap between B is set to B, the indentation rate defined by 100? (AB) / A is 40% or more, preferably 60% or more. For this reason, the indentation of a terminal can be observed from the flexible substrate side, and also it can be made not to increase the connection resistance of the anisotropic conductive connection part by an anisotropic conductive adhesive film under a thermo-wetting test. In addition, when an indentation rate is 0% (A-B is 0), it means the state which electroconductive particle was pushed between terminals, without being stuck in a terminal. Moreover, when an indentation rate is 100% (B is 0), it means the state which electroconductive particle fully pressed in the terminal of a flexible substrate.

Since the particle diameter of the electroconductive particle which comprises the anisotropic conductive adhesive film of this invention becomes hard to produce an indentation to the terminal of a flexible substrate, when it is too small, it is 4 micrometers or more, Preferably it is 6 micrometers or more. Although the upper limit of a particle diameter can be suitably determined according to the pitch, thickness variation, etc. of the terminal to be connected, 15 micrometers or less are preferable. The range of the more preferable particle diameter is 6? 10 μm.

Since the compressive hardness of the electroconductive particle used in this invention becomes difficult to produce indentation in the terminal of a flexible board | substrate when it is too low, it is 4500 kgf / mm <2> or more, Preferably it is 6000 kgf / mm <2> or more. Moreover, since it exists in the tendency for connection reliability to fall when too high, 7000 kgf / mm <2> or less is preferable. Here, a compressive hardness is synonymous with the compressive strength at the time of 10% compression displacement, and can be measured using a general micro compression tester.

Moreover, the electroconductive particle used in this invention has a sphericity degree of 5 or less, when defining the sphericity degree as a / b, when the maximum diameter obtained by metal microscopic observation makes a and the minimum diameter is b, Preferably, the sphericity of 3 or less is shown. This is because the connection reliability tends to be lowered when the sphericity exceeds 5. In addition, when the maximum diameter a is too small, the indentation tends to be less likely to be expressed, and when too large, the anisotropic conductivity tends to be lowered. 15 µm, more preferably 6? 10 μm. On the other hand, if the minimum diameter b is too small, the indentation tends to be less likely to be expressed, and if too large, the anisotropic conductivity tends to be lowered. 15 µm, more preferably 6? 10 μm. In addition, in this invention, a sphericity is necessarily 1 or more logically.

Examples of the conductive particles having the properties described above include metal particles such as nickel, cobalt, silver, copper, gold, palladium and solder, electroless nickel plated films and the like on the surfaces of resin particles such as divinylbenzene resin and benzoguanamine resin. The electroless plating film of which is formed is applicable.

As a binder resin composition which disperses such electroconductive particle, the binder resin composition used for the well-known anisotropic conductive adhesive film can be employ | adopted. For example, it can comprise with a film forming resin, a liquid epoxy compound (hardening component) or an acrylic monomer (hardening component), a hardening | curing agent, a silane coupling agent, etc.

Examples of the film-forming resins include phenoxy resins, epoxy resins, unsaturated polyester resins, saturated polyester resins, urethane resins, butadiene resins, polyimide resins, polyamide resins, polyolefin resins, and the like. can do. Among these, phenoxy resin can be used preferably from a film forming property, workability, and connection reliability point.

As a liquid epoxy compound, a bisphenol-A epoxy compound, a bisphenol F-type epoxy compound, a novolak-type epoxy compound, those modified epoxy compounds, an alicyclic epoxy compound, etc. are mentioned, These 2 or more types can be used together. In this case, as a hardening | curing agent, latent hardening | curing agents, such as cationic hardening | curing agents, such as anionic hardening | curing agents, such as a polyamine and an imidazole, and a sulfonium salt, and a phenolic hardening | curing agent, are mentioned.

As an acryl monomer, methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, isobutyl (meth) acrylate, ethylene glycol (meth) acrylate, and ethylene glycol di (meth) acrylate , Diethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylol methane tetra (meth) acrylate, and the like. In this case, an organic peroxide, azobisbutyronitrile, etc. are mentioned as a hardening | curing agent (radical polymerization initiator).

As a silane coupling agent, an epoxy silane coupling agent, an acryl-type silane coupling agent, etc. are mentioned. These silane coupling agents are mainly alkoxysilane derivatives.

A filler, a softener, an accelerator, an anti-aging agent, a coloring agent (pigment, dye), an organic solvent, an ion catcher agent, etc. can be mix | blended with a binder resin composition as needed.

When content of the electroconductive particle in the anisotropic conductive adhesive film of this invention is too small, connection reliability will fall, and when too much, anisotropic conductivity will fall, Preferably it is 0.3? 30 mass%, More preferably, it is 5? 10 mass%.

Although the thickness of the anisotropic conductive adhesive film of this invention is not specifically limited, Usually, 10? 45 μm.

The anisotropic conductive adhesive of this invention can be prepared by putting a binder resin composition structural component and electroconductive particle into a stirring container, and mixing according to a conventional method.

Next, the bonded structure of this invention manufactured using the anisotropic conductive film of this invention is demonstrated.

The connection structure of this invention is a connection structure with which the terminal of a flexible board and the terminal of a rigid board which were demonstrated previously are anisotropic electrically conductively connected via the anisotropic conductive adhesive film in which electroconductive particle is disperse | distributed to a binder resin composition, An anisotropic conductive film of the present invention is used as an anisotropic conductive adhesive film to be sandwiched between a terminal and a terminal of a rigid substrate. Since this bonded structure uses the anisotropic conductive film of this invention, when the particle diameter of the electroconductive particle after anisotropic conductive connection is set to A, and the gap between the terminal of a flexible board | substrate and the terminal of a rigid board | substrate is set to 100? It has a structure in which electroconductive particle penetrates into the terminal of a flexible substrate so that the indentation rate defined by (AB) / A may be 40% or more, Preferably it is 60% or more. In this case, in order to facilitate observation of the indentation of electroconductive particle from a flexible substrate, it is preferable that electroconductive particle does not penetrate into the terminal of a rigid substrate.

As a specific example of such a bonded structure of this invention, a liquid crystal display device, an organic electroluminescence display, a solar cell module, an LED illuminating device, etc. are mentioned.

The bonded structure of this invention can be manufactured as demonstrated below.

First, the anisotropic conductive adhesive film of this invention is temporarily attached on the terminal of a rigid board | substrate according to a conventional method. Then, the flexible substrate is placed so that the terminals of the flexible substrate correspond to the terminals of the rigid substrate, sandwiching the anisotropic conductive adhesive film.

Next, anisotropic conductive connection is performed by heat-pressing an anisotropic conductive adhesive film with a heating bonder from the flexible substrate side. In this case, when the particle diameter of the electroconductive particle after anisotropic conductive connection is set to A, and the gap between the terminal of a flexible board | substrate and the terminal of a rigid board | substrate is B, the indentation rate defined by 100 (AB) / A is 40% or more. Anisotropic conductive connection is performed while considering the compounding composition of a binder resin composition, the material of electroconductive particle, the surface state of a terminal, etc. so that it may become. For this reason, the bonded structure of this invention can be obtained.

In addition, control of a press-fit rate can be performed by adjusting the heating press conditions etc. at the time of anisotropic conductive connection. For example, the indentation rate can be raised by lowering heating temperature or raising pressurization pressure. In contrast, the indentation ratio can be lowered by increasing the heating temperature or lowering the pressurizing pressure. Moreover, it can also adjust by selecting raw materials, such as a flexible board | substrate, a rigid board | substrate, those terminals, and electroconductive particle. Moreover, it can also adjust in combination.

Example

Hereinafter, the present invention will be described in detail with reference to examples.

Example 1? 13, comparative example 2? 5

(Preparation of conductive particles)

100 g of nickel particles having an average particle diameter of Table 1 were stirred for 5 minutes in an aqueous solution of 50 ml / L hydrochloric acid. 1 L (pH 6, temperature 60 degreeC) of the aqueous solution containing EDTA-4Na (10 g / L) and citric acid-2Na (10 g / L) contains the nickel particle which filtered this and washed once with the pulp. It was added to the reaction vessel with stirring while stirring.

Subsequently, in the obtained mixed aqueous solution in the reaction vessel, a mixture containing gold potassium cyanide (10 g / L, 6.8 g / L as Au), EDTA-4Na (10 g / L) and citric acid-2Na (10 g / L) 300 ml of an aqueous solution (Liquid A) and 300 ml of a mixed aqueous solution (Liquid B) containing potassium borohydride (30 g / l) and sodium hydroxide (60 g / l) were simultaneously added from different inlets for 20 minutes Then, electroless gold plating was performed by continuing stirring for 10 minutes.

After completion of the gold plating, the mixed solution was filtered, the filtrate was washed three times with pulp, dried using hot air at 100 ° C., and heated to about 10 ° C. on the surface of the nickel powder. Electroconductive particle in which the 20-nm-thick electroless gold plating thin film was formed was obtained. Since the electroless gold plating thin film is very thin, the average particle diameter of this electroconductive particle can be approximated to the average particle diameter of the nickel particle of a raw material.

In addition, the average particle diameter of nickel particle is the particle diameter in the point which cumulative mass corresponds to 50% by measuring particle size distribution by a laser diffraction scattering method (measurement apparatus: micro truck MT3100, Nikkiso Co., Ltd.). .

Moreover, the compressive hardness at the time of 10% compression displacement of the obtained electroconductive particle was measured using the micro compression tester (PCT-200, Shimadzu Corporation). The obtained results are shown in Table 1.

The sphericity of electroconductive particle image | photographed electroconductive particle using the metal microscope (MX51, Olympus Co., Ltd.), calculated | required the largest diameter a and the minimum diameter b of particle | grains, and computed a / b as a sphericity degree. The obtained results are shown in Table 1.

(Production of Anisotropic Conductive Adhesive Film)

22 parts by mass of phenoxy resin (YP-50, Shin-Nika Epoxy Co., Ltd.), 5 parts by mass of dicyclopentadiene dimethacrylate (DCP, Shin-Nakamura Chemical Industry Co., Ltd.), urethane Acrylate (M-1600, Toa Synthetic Co., Ltd.) 10 parts by mass, acrylic rubber (SG-80H, Nagase Chemtex Co., Ltd.) 5 parts by mass, phosphorus-containing methacrylate (PM2, Nippon Gunpowder Co., Ltd.) 1 Mass part, 2 mass parts of diacyl peroxide type initiators (niper BW, Nichi Oil Co., Ltd.), and 50 mass parts of toluene are mixed, and the obtained mixture is apply | coated to a peeling sheet so that dry thickness may be 35 micrometers, and it is 5 at 80 degreeC. The anisotropic conductive adhesive film was obtained by drying for minutes.

Using the obtained anisotropic conductive adhesive film, a polyimide flexible substrate (polyimide thickness 38 micrometers, copper wiring pitch 200 micrometers, wiring height 8 micrometers), and a printed wiring board (FR-4 grade, Panasonic Corporation: copper wiring pitch 200 micrometers, wiring height 35 micrometers), and the anisotropic conductive connection was carried out on the heating pressurization conditions of 170 degreeC, 4 Mpa, and 5 second, and the bonded structure was produced.

The end face of the anisotropic conductive connection of the obtained bonded structure was polished, the particle diameter A and the gap B between the wirings (gap between terminals on which the conductive particles were sandwiched) were measured with a metal microscope, and the indentation ratio of the conductive particles (= (AB) / A) was calculated | required. The obtained results are shown in Table 1.

Moreover, about the obtained bonded structure, the connection resistance at the time of storing for 500 hours in the high temperature, high humidity environment of 85 degreeC of temperature and 85% of humidity was measured, and connection reliability was evaluated by the following references | standards. The obtained results are shown in Table 1. In practical use, the evaluation result is preferably A or B.

Rank evaluation criteria

A: Connection resistance is less than 2.0 Ω

B: Connection resistance value is 2.0 Ω or more and less than 4.0 Ω

C: Connection resistance is 4.0 Ω or more

Moreover, FIG. 1 of Unexamined-Japanese-Patent No. 2008-91843 is shown. The same structural apparatus as the measuring apparatus of FIG. 3 was manufactured, the indentation of the wiring (terminal) by electroconductive particle was observed from the flexible board side using the connection part of a bonded structure, and the indentation state was evaluated on the following references | standards. The obtained results are shown in Table 1. In practical use, the evaluation result is preferably A or B. Incidentally, the indentation is caused by deformation of the flexible substrate.

Rank evaluation standard

A: Indentation was confirmed at 8 or more points out of 10 observation points of the connection part.

B: 1? Indentation found at 7 points

C: Indentation is not confirmed among 10 observation points

Comparative Example 1

The palladium catalyst was supported by the immersion method on the divinylbenzene-type resin particle (5g) of 8 micrometers of average particle diameters. The resin particles were then electroless nickel plated using an electroless nickel plating solution (pH 12, plating solution temperature 50 ° C.) prepared from nickel sulfate hexahydrate, sodium hypophosphite, sodium citrate, triethanolamine and thallium nitrate. And the nickel coating resin core particle in which the nickel plating layer (10-20 nm thickness) was formed in the surface was obtained as electroconductive particle.

Ni-Au coating resin core particles were obtained as electroconductive particles by performing the electroless gold plating treatment on the obtained nickel coating resin core particles in the same manner as in Example 1.

About the obtained electroconductive particle, the average particle diameter, compressive hardness, and sphericity degree were calculated | required similarly to Example 1, and the obtained result is shown in Table 1. Moreover, similarly to Example 1, the anisotropic conductive adhesive film was produced, the indentation rate of electroconductive particle was calculated | required, the connection reliability was evaluated, and the indentation state was further evaluated. The obtained results are shown in Table 1.

From Table 1, Example 1? In the case of the bonded structure manufactured using the anisotropic conductive adhesive film of 13, all the evaluation results of connection reliability and an indentation state were A or B, and there was no problem practically.

On the other hand, in the case of the bonded structure manufactured using the anisotropic conductive adhesive film of Comparative Example 1, the compressive hardness at the time of 10% compression deformation of the used conductive particles was very low at 700 kgf / mm 2, and the indentation rate of the conductive particles was also 12 Since it was low at%, evaluation of the indentation state was C.

In the case of the bonded structure manufactured using the anisotropic conductive adhesive film of the comparative example 2, since the average particle diameter of the used electroconductive particle was 3 micrometers small, evaluation of the indentation state was C.

In the case of the bonded structure manufactured using the anisotropic conductive adhesive film of the comparative example 3, since the sphericity was 5.3, the evaluation of connection reliability was C.

In the case of the bonded structure manufactured using the anisotropic conductive adhesive film of the comparative example 4, since the average particle diameter of the used electroconductive particle was 3 micrometers small, evaluation of the indentation state was C.

In the case of the bonded structure manufactured using the anisotropic conductive adhesive film of the comparative example 5, since the indentation rate of electroconductive particle was 35%, evaluation of the indentation state was C.

Industrial availability

The anisotropic conductive adhesive film of this invention limits the particle diameter, compressive hardness, and sphericity degree of the electroconductive particle to be used to a specific range, respectively. For this reason, when the particle diameter of the electroconductive particle in the bonded structure after anisotropic conductive connection is set to A, and the gap between the terminal of a flexible board | substrate and the terminal of a rigid board | substrate is set to B, it is press-in defined as 100 (AB) / A. The rate can be 40% or more. Therefore, the indentation of a terminal can be observed from the flexible board side of a bonded structure, and also favorable connection reliability can be ensured even when it preserve | stores in a high temperature, high humidity environment. Therefore, the anisotropic conductive adhesive film of this invention is useful at the time of anisotropic conductive connection of a flexible substrate and a rigid substrate.

1: electroconductive particle
2: rigid substrate
3: terminal of rigid board
4: flexible substrate
5: Terminal of Flexible Board
A: particle diameter of conductive particles
B: gap between terminals

Claims (6)

In the anisotropic conductive adhesive film for anisotropic conductive connection of the terminal of a flexible board | substrate and the terminal of a rigid board | substrate, In an anisotropic conductive adhesive film in which electroconductive particle is disperse | distributed to a binder resin composition,
When the particle diameter of the electroconductive particle after anisotropic conductive connection is set to A, and the gap between the terminal of a flexible board | substrate and the terminal of a rigid board | substrate is B, so that the indentation rate defined by 100 (AB) / A may be 40% or more, The sphericity of the electroconductive particle represented by a / b when electroconductive particle has a particle diameter of 4 micrometers or more, the compressive hardness of 4500 kgf / mm <2> or more, and makes the maximum diameter of electroconductive particle into a, and the minimum diameter into b,眞 球 度) is 5 or less, The anisotropic conductive adhesive film characterized by the above-mentioned. The method of claim 1,
The anisotropic conductive adhesive film whose compressive hardness of electroconductive particle is 7000 kgf / mm <2> or less, particle diameter is 15 micrometers or less, and a sphericity degree is 5 or less. In the bonded structure in which the terminal of a flexible board | substrate and the terminal of a rigid board | substrate were anisotropic electrically conductively connected through the anisotropic conductive adhesive film in which electroconductive particle is disperse | distributed to a binder resin composition,
The electroconductive particle of the anisotropic conductive adhesive film which should be clamped between the terminal of a flexible board | substrate and the terminal of a rigid board | substrate has a particle diameter of 4 micrometers or more, and a compressive hardness of 4500 kgf / mm <2> or more, and makes the maximum diameter a, and is the minimum When the diameter was b, the sphericity of the conductive particles represented by a / b is 5 or less,
When the particle diameter of the electroconductive particle after anisotropic conductive connection is set to A, and the gap between the terminal of a flexible board | substrate and the terminal of a rigid board | substrate is B, so that the indentation rate defined by 100 (AB) / A may be 40% or more, Electroconductive particle penetrates into the terminal of a flexible substrate, The connection structure characterized by the above-mentioned. The method of claim 3, wherein
The bonded structure wherein the rigid substrate is a glass substrate. The method according to claim 3 or 4,
The compressed structure of electroconductive particle is 7000 kgf / mm <2> or less, particle diameter is 15 micrometers or less, and sphericity is 5 or less. As a manufacturing method of the bonded structure of Claim 3,
The flexible board | substrate is arrange | positioned so that the anisotropic conductive adhesive film of Claim 1 or 2 may be temporarily attached on the terminal of a rigid board | substrate, the said anisotropic conductive adhesive film is sandwiched, and the terminal of a flexible board may correspond to the terminal of a rigid board | substrate. ,
When the particle diameter of the electroconductive particle after anisotropic conductive connection is set to A, and the gap between the terminal of a flexible board | substrate and the terminal of a rigid board | substrate is B, so that the indentation rate defined by 100 (AB) / A may be 40% or more, An anisotropic conductive connection is performed by heat-pressing an anisotropic conductive adhesive film with a heating bonder from the flexible substrate side.

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