JPH1173818A - Conductive particle, anisotropic conductive adhesive and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive particle, an isotropic conductive adhesive and a liquid crystal display device that are new and can offer an excellent conductive connection without deforming or damaging the wiring pattern on a board and an externally leading electrode on the board. SOLUTION: An anisotropic conductive adhesive is made by including conductive particles 1 in an insulating adhesive; when a predetermined compressive load is imposed on the anisotropic adhesive between the conductive members in order to make conductive bonding between multiple conductive members (for instance, two wiring patterns) together by using the anisotropic conductive adhesive, the recessed and projecting parts 6 of the conductive particles 1 are formed enough to reach the conductive members by pushing aside the insulating adhesive existing among the conductive particles and the conductive members.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of electrically connecting a plurality of substrates with their wiring patterns facing each other, and providing a conductive pattern between an external lead wiring electrode of one element substrate and a wiring electrode terminal of another device. The present invention relates to a conductive particle, an anisotropic conductive adhesive, and a liquid crystal display device used for connection purposes.

[0002]

2. Description of the Related Art Conventionally, for example, two wiring boards each having a wiring pattern formed on the surface thereof are bonded in a state where the wiring patterns of the respective boards face each other, and the wiring patterns on the same board are insulated and face each other. An anisotropic conductive adhesive (anisotropic conductive film) is used as an adhesive to secure electrical conductivity between wiring patterns (securing insulation in the horizontal direction and ensuring conductivity only in the vertical direction). Anisotropic conductive films). Such an anisotropic conductive adhesive (anisotropic anisotropic conductive adhesive) is an adhesive component having thermal adhesiveness and electrical insulation.
(Insulating adhesive; binder) Provided as a film in which conductive particles are dispersed. Specifically, when the anisotropic conductive adhesive (anisotropic conductive film; anisotropic conductive film) is sandwiched between two wiring boards and the two wiring boards are heated and pressed, the wiring pattern is formed. The insulating adhesive in the formed portion moves in the horizontal direction, and the wiring patterns facing each other on the two substrates are electrically connected by conductive particles in the vertical direction. Electrical connection can be secured. That is, anisotropic conductive bonding can be performed.

In such an anisotropic conductive adhesive, conductive particles formed by coating (coating) a conductive layer (conductive metal film) on the surface of metal particles or hard resin particles are used. I have. Such conductive particles usually have high hardness and thus make point contact with the wiring pattern on the substrate.

[0004]

However, in the case of conventional conductive particles, the conductive particles are used as an anisotropic conductive adhesive so that a plurality of conductive members (for example, two wiring patterns) are conductively bonded. In this case, the insulating adhesive remains between the conductive particles and the wiring pattern, for example, and there has been a problem that good conductivity between the conductive particles and the wiring pattern may not be secured.

The present invention relates to a novel conductive particle and an anisotropic conductive particle capable of obtaining an extremely good conductive connection without deforming or damaging a wiring pattern on a substrate or an external lead-out electrode on the substrate. It is an object of the present invention to provide an adhesive and a liquid crystal display device.

[0006]

In order to achieve the above object, according to the first aspect of the present invention, in the conductive particles having irregularities on the surface, the conductive particles are contained in an insulating adhesive. When a predetermined compressive load is applied to the anisotropically conductive adhesive between the conductive members in order to electrically bond between the plurality of conductive members using the anisotropically conductive adhesive, In addition, the irregularities on the surface of the conductive particles are formed to an extent sufficient to reach the conductive member by eliminating the insulating adhesive interposed between the conductive particles and the conductive member. Features.

[0007] According to the second aspect of the present invention, the first aspect is provided.
In the conductive particles described above, the irregularities on the surface of the conductive particles have a depth in the range of 0.05 to 2 μm, and the surface density of the convex portions of the irregularities is 1000 to 500.
000 / mm ² .

[0008] According to the third aspect of the present invention, the first aspect of the present invention.
Or the conductive particles according to claim 2, wherein the conductive particles are obtained by forming a conductive layer on the surface of core material particles, and the irregularities on the surface of the conductive particles are irregularities on the conductive layer. It is characterized by being defined by.

Further, according to the invention described in claim 4, according to claim 1,
4. The conductive particles according to claim 3, which have a characteristic as a hard elastic sphere at a normal temperature under a compressive load of 2 gf / particle to 3 gf / particle, and a compressive load of 2 gf / particle. It is characterized by crushing and plastic deformation when particles reach 3 gf / particle.

Further, according to the invention described in claim 5, according to claim 1,
The conductive particles according to any one of claims 4 to 4 are dispersed in the insulating adhesive at a predetermined ratio.

Further, according to the invention described in claim 6, according to claim 5,
In the anisotropic conductive adhesive described, the anisotropic conductive adhesive is formed as a film-like film, and in this case, the relationship between the particle diameter D of the conductive particles and the film thickness T of the insulating adhesive. Satisfies D ≧ T.

Further, according to the invention described in claim 7, according to claim 5,
Or the anisotropic conductive adhesive according to claim 6, wherein the average particle diameter of the conductive particles dispersed in the insulating adhesive is in the range of 2 μm to 30 μm, and the CV value of the conductive particles. Is 20% or less.

According to the present invention, a wiring electrode for external drawing of a liquid crystal display element using a resin substrate and a flexible wiring electrode terminal for a predetermined device are provided.
When performing thermocompression bonding using the anisotropic conductive adhesive according to any one of claims 7 to 7, the compression deformation rate of the conductive particles of the anisotropic conductive adhesive during thermocompression bonding is 20 to 80. %.

According to the ninth aspect of the present invention, the external wiring electrode of the liquid crystal display element using the resin substrate and the flexible wiring electrode terminal for the predetermined device are provided.
A thermocompression connection is made using the anisotropic conductive adhesive according to any one of claims 8 to 8.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a diagram (cross-sectional view) illustrating a configuration example of the conductive particles according to the present invention. Referring to FIG. 1 (a), as described later, the conductive particles 1 are contained in an insulating adhesive to form an anisotropic conductive adhesive. When a predetermined compressive load is applied to the anisotropic conductive adhesive between the conductive members in order to conductively bond between a plurality of conductive members (for example, two wiring patterns) using a material, the surface of the conductive particles 1 The irregularities 6 are formed to a degree sufficient to reach the conductive member by removing the insulating adhesive interposed between the conductive particles and the conductive member.

When the conductive particles 1 of the present invention are used for an anisotropic conductive adhesive (anisotropic conductive film) as described later, the conductive particles 1 are usually 2 to 50 μm, preferably 5 to 30 μm.
It is preferable to have an average particle diameter (average diameter) of m.

In this case, the irregularities 6 on the surface of the conductive particles are
For example, the depth is in the range of 0.05 to 2 μm, and the surface density of the projections of the unevenness 6 is 1000 to 5 μm.
It is in the range of 00000 / mm ² .

More specifically, the conductive particles 1 are shown in FIG.
As shown in (b), the core material particles 2 and the conductive layer 3 formed on the surface of the core material particles 2, and the irregularities 6 on the surface of the conductive particles 1 3 asperities.

Here, the conductive layer 3 can be formed of a conductive metal, an alloy containing these metals, a conductive ceramic, a conductive metal oxide, or another conductive material.

Examples of the conductive metal include Zn, Al, S
b, U, Cd, Ga, Ca, Au, Ag, Co, Sn,
Se, Fe, Cu, Th, Pb, Ni, Pd, Be and Mg can be mentioned. The above-mentioned metals may be used alone, or two or more kinds may be used, and other elements and compounds (for example, solder) may be added. Examples of conductive ceramics include Vo ₂ , Ru ₂ O, SiC,
ZrO ₂ , Ta ₂ N, ZrN, NbN, VN, TiB ₂ ,
_{ZrB, HfB 2, TaB 2,} MoB 2, CrB 2, B
₄ C, mention may be made of MoB, ZrC, a VC and TiC. In addition, as conductive materials other than the above, carbon particles such as carbon and graphite, and ITO
And the like.

Among such conductive materials, it is particularly preferable that the conductive layer 3 contains gold. Conductive layer 3
By adding gold to the metal, the electric resistance value is reduced, the spreadability is improved, and good conductivity can be obtained. In addition, since gold has low hardness, as described later, an anisotropic conductive adhesive (anisotropic conductive film, anisotropic conductive film) containing the conductive particles 1 is used to perform conductive bonding between the electrodes. In such a case, there is little damage to the electrodes and the like.

In particular, as the conductive layer 3, as shown in FIG. 2, for example, gold (A) is formed on the surface of a nickel (Ni) metal layer 3a.
u) It is preferable to use the one on which the layer 3b is formed (substituted by gold (Au)).

The above-mentioned various conductive layers 3 are formed by a physical method such as a vapor deposition method, an ion sputtering method, an electroless plating method and a thermal spraying method, and a conductive material is scientifically applied to the surface of a resin core material having a functional group. A method of adsorbing a conductive material on the surface of a core material using a surfactant or the like, a method of bonding conductive particles to a reaction system when forming a core material, The core material and the conductive layer can be simultaneously formed while precipitating the conductive particles. In particular, it is preferable to form this conductive layer by an electroless plating method, and to promote the oxidation-reduction reaction in the electroless plating step by increasing the palladium concentration in the pretreatment step of the electroless plating compared to the conventional method. Good. Also,
Such a conductive layer does not need to be a single layer, and a plurality of layers may be stacked.

The thickness of the conductive layer 3 is usually 0.01 to 10.0 μm, preferably 0.05 to 5 μm.
m, more preferably in the range of 0.2 to 2 μm.
An insulating layer made of an insulating resin may be further formed on the surface of the composite particles. As an example of a method of forming an insulating layer, a method of forming a discontinuous insulating layer made of polyvinylidene fluoride by a hybridization system is described.
85 to 11 parts by weight of polyvinylidene fluoride, 85 to 11 parts by weight
Treat at a temperature of 5 ° C. for 5-10 minutes. The thickness of this insulating layer is usually about 0.1 to 0.5 μm. Note that the insulating layer may incompletely cover the surface of the conductive particles.

As described above, in the conductive particles 1 of the present invention, any conductive material can be used for the conductive layer 3, and the conductive layer 3 can have any layer structure. The conductive particles 1 are contained in an insulating adhesive to form an anisotropic conductive adhesive, and a plurality of conductive members are conductively bonded using the anisotropic conductive adhesive. When a predetermined compressive load is applied to the anisotropic conductive adhesive, irregularities sufficient to reach the conductive member by eliminating the insulating adhesive interposed between the conductive particles and the conductive member are obtained. It must be formed on the surface. More specifically, the unevenness of the conductive layer 3 has a depth in the range of 0.05 to 2 μm, and the surface density of the unevenness is 1000 to 5000.
It must be formed in the range of 00 pieces / mm ² .

FIGS. 3A and 3B show the conductive particles 1 of the present invention.
3 is a photograph showing an example of the above. FIGS. 4 (a) and 4 (b) show conventional conductive particles (conductive particles having almost no irregularities on the surface) for comparison with the conductive particles 1 of FIGS. 3 (a) and 3 (b). A photograph of one example is also shown. 3 (a), 3 (b), 4 (a),
(b) shows conductive particles having a particle diameter of 20 μm in about 4000
Photographed at double magnification.

Here, the conductive particles 1 of the present invention shown in FIGS. 3A and 3B use polystyrene for the core particles 2, and the conductive layer 3 contains the polystyrene core particles 2. The palladium concentration in the pretreatment step of electroless plating is twice the concentration of a conventionally known method, electroless Ni plating is performed, and the surface is further Au-plated.

The conventional conductive particles 1 shown in FIGS. 4 (a) and 4 (b) are obtained by forming the conductive layer 3 by a conventionally known electroless Ni plating.

Due to such a difference in the conductive material and the manufacturing process, the conductive particles 1 of the present invention shown in FIGS.
Compared to the conventional conductive particles of (a) and (b), the surface has irregularities of sufficient depth and surface density.
(b) The conductive particles of the present invention are contained in an insulating adhesive to form an anisotropic conductive adhesive, and a plurality of conductive members (for example, wiring patterns) are formed using the anisotropic conductive adhesive. When a predetermined compressive load is applied to the anisotropic conductive adhesive between the conductive members in order to conductively bond the conductive particles, the unevenness 6 on the surface of the conductive particles 1 causes the insulating material interposed between the conductive particles and the conductive member. The conductive adhesive can be eliminated to reach the conductive member, and therefore, even if the insulating adhesive is present, the conductive particles 1 and the conductive member (for example, a wiring pattern) can be reliably conductive. Connection can be established.

As described above, the conductive particles 1 of the present invention are characterized by having the above-described irregularities 6 on the surface thereof. In addition to this feature, when the conductive particles 1 are further subjected to a compressive load, compressive deformation characteristics of the may be provided with features such as indicated by C ₁ in FIG. In FIG. 5, the compression deformation characteristic C ₂ or C ₃ of a conventional conductive particle is also shown. Note that the compression deformation characteristics shown in FIG.
It is obtained as the amount of compressive deformation S (mm) (or the compressive deformation ratio (%)) of the particles when a compression load F is applied to the particles at room temperature (23 ° C.).

FIG. 6A shows the state of the conductive particles before the application of the compression weight F, and FIG. 6B shows the state of the conductive particles when the compression weight F is applied. Figure 6
From (a) and (b), the amount of compressive deformation S (mm) and the rate of compressive deformation (%) of the conductive particles are represented by x ₀ which is the particle diameter before applying the compression load F.
Where x is the particle size in the compression direction when the compression load F is applied, the amount of compressive deformation S (mm) = (x ₀ −x), the rate of compressive deformation (%) = (x ₀ −x) / x Is required. FIG.
In this example, as the conductive particles, the particle size x ₀ before adding the compressive load F is used as the order of approximately 20 [mu] m.

Referring to FIG. 5, the conventional conductive particles having a compressive deformation characteristic of C ₂ are elastically deformed when the compressive load (gf / particle) is increased. It has a characteristic with a high rate. That is, it has characteristics as a soft elastic sphere.

Conventional conductive particles having a compressive deformation characteristic of C ₃ are also elastically deformed as the compressive load (gf / particle) increases. The compression deformation ratio is small.
That is, it has characteristics as a hard elastic sphere.

[0034] In contrast, the conductive particles 1 of the present invention C ₁
When the conductive particles 1 of the present invention have an initial compression load of F, the compression load F is 2 gf / particle to 3 gf / particle at normal temperature in the example of FIG. Although it has elastic properties of hardness almost the same as that of the conventional conductive particles having a compressive deformation property of C ₃ (although it has properties as a hard elastic sphere), a compressive load is 2 gf / particle to 3 g.
When the load value of f / particle is reached (at an early stage), it is crushed and plastically deformed. Here, crushing means that the conductive particles 1 are plastically crushed (plastically deformed) by pressure and do not return to the original shape even when the pressure is released.

[0035] In other words, the conductive particles 1 of the present invention C ₁
When the conductive particles 1 of the present invention have a compressive deformation characteristic of, as shown in FIG.
When the compressive deformation rate of the conductive particles 1 is in the range of 5 to 40%, the conductive particle 1 has an inflection point at which the compressive deformation rate sharply increases.

More specifically, the K value can be used as a value for evaluating the compressive deformation characteristics of the conductive particles (an index for evaluating hardness). That is, F is the compression load (kgf), S is the amount of compressive deformation (mm), R is the particle radius (mm), and the compressive elastic deformation characteristics of one conductive particle are expressed by the following equation (Equation 1). If the conductive particles 1 of the compressive deformation characteristics of C ₁
Means that the K value is 10 to 10 when the compressive deformation rate is 40%.
0 (kgf / mm ² ).

[0037]

## EQU1 ## K = ( ^3/21/2 ). (S-3 ^{/ 2} ). (R- ^{1 / 2} ) ^.F

The above equation (1) is derived as follows. That is, in general, relation between compressive load and deformation amount of the elastic spheres, compression modulus E (kgf / mm ²⁾
When σ is the Poisson's ratio, it can be approximately obtained by the following equation (Equation 2) by applying Schulz's equation.

[0039]

F = (2 ^1/2/3 ) (S ^3/2 ) (R ^1/2 ) (E) / (1−σ ² )

Here, if K = (E) / (1−σ ² ), Equation 1 is derived. Then, in Equation 1, the K value can be obtained from the actually measured values F, S, and R.

In this case, the conductive particles 1 having a compressive deformation characteristic of C ₁ have a K value of 10 to 10 when the compressive deformation ratio is 40%.
Since the compression deformation rate is 100 (kgf / mm ² ) in the above example, it has characteristics as a hard elastic sphere at the stage of the initial load until the compression deformation rate reaches 40%.

The conductive particles 1 having a compressive deformation characteristic of C ₁ have the characteristics of a hard elastic sphere as described above at the initial stage when the compressive load is relatively small. When it grows to some extent, it suddenly collapses,
It has the property of plastic deformation. That is, when the particle deformation ratio is in the range of 5 to 40%, there is an inflection point at which the compression deformation ratio sharply increases.

The compression deformation characteristics C of such conductive particles 1
₁ can give the core material particles 2 of the conductive particles 1. In this case, the core particles 2 having a compressive deformation characteristics C ₁ as described above can be formed of an inorganic material or an organic material. At this time, the core material particles 2 may be solid particles or hollow particles, and furthermore, １ ／ to 1/1 of the average particle size of the core material particles to be used.
An aggregate of fine particles having a particle diameter of about 00 may be used.

More specifically, when the core material particles are formed using an inorganic material, hollow glass particles, hollow silica particles, hollow shirasu particles, hollow ceramic particles, aggregated silica particles, and the like can be used.

As described above, the above-mentioned inorganic material can be used as the core material particles 2. However, since the inorganic material is relatively hard, in the present invention, the resin (polymer) is used as the core material particles 2. ) It is preferable to use particles (for example, particles made of a plastic material).

Among the core particles 2 forming the conductive particles 1, core particles made of resin particles include, for example, (meth) acrylate resin, polystyrene resin, and styrene- (meth) resin.
It can be formed of an acrylic copolymer resin, a urethane resin, an epoxy resin, a polyester resin, or the like.

For example, when the core particles are formed of a (meth) acrylate resin, the (meth) acrylic resin is
It is preferably a copolymer of a (meth) acrylic acid ester, a compound having a reactive double bond copolymerizable therewith, if necessary, and a bifunctional or polyfunctional monomer.

When the core particles are formed of a polystyrene resin, the polystyrene resin may be a styrene derivative, and if necessary, a compound having a reactive double bond copolymerizable therewith and a bifunctional compound. Alternatively, it is preferably a copolymer with a polyfunctional monomer.

However, in the case of a normal (meth) acrylate resin or polystyrene resin, the compression breaking strength is high when the crosslinking density is high, and the conductive particles do not become crushed by the pressure at the time of thermocompression bonding. In the case of cross-linking or low cross-linking density, the conductive particles are crushed at a compression load of less than 2 gf / particle, and good performance cannot be obtained. To make the compressive fracture strength within the above range (compressive load is 2
The conductive particles are crushed when a load value in the range of gf / particle to 3 gf / particle is reached).

When the core particles have core particles made of a (meth) acrylic resin, the (meth) acrylic resin is preferably a (co) polymer of a (meth) acrylic acid ester. A copolymer of this (meth) acrylic ester-based monomer and another monomer can also be used.

Here, examples of the (meth) acrylate-based monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate,
Butyl (meth) acrylate, 2-ethylhexyl (meth)
Acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-propyl (meth) acrylate, chloro-2-hydroxyethyl (meth) acrylate, diethylene glycol mono Examples include (meth) acrylate, methoxyethyl (meth) acrylate, glycidyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, and isoboronor (meth) acrylate.

When the core particles forming the conductive particles are a polystyrene resin, specific examples of the styrene monomer include styrene, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, and diethylstyrene. Alkylstyrenes such as triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, hebutylstyrene and octylstyrene; halogenated styrenes such as fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, iodostyrene and chloromethylstyrene; and nitro Styrene, acetylstyrene and methoxystyrene can be mentioned.

The core particles are preferably formed of one of the above-mentioned (meth) acrylic resin and styrene resin alone, but are formed of a composition comprising these resins. Is also good. Further, a copolymer with the above-mentioned (meth) acrylic ester-based monomer and styrene-based monomer may be used.

Further, the (meth) acrylic resin or styrene resin may contain another monomer copolymerizable with the (meth) acrylate monomer and / or the styrene monomer as required. And may be copolymerized.

Examples of the above-mentioned (meth) acrylate-based monomer or other monomer copolymerizable with the styrene-based monomer include vinyl monomers and unsaturated carboxylic acid monomers.

Here, specific examples of the vinyl monomer include vinyl pyridine, vinyl pyrrolidone, vinyl carbazole, vinyl acetate and acrylonitrile;
Conjugated diene monomers such as butadiene, isoprene and chloroprene; vinyl halides such as vinyl chloride and vinyl bromide; and vinyldene halides such as vinylidene chloride.

Specific examples of the unsaturated carboxylic acid monomer include (meth) acrylic acid, α-ethyl (meth) acrylic acid, crotonic acid, α-methyl crotonic acid, α-ethyl crotonic acid, and isocrotonic acid. , Addition-polymerizable unsaturated aliphatic monocarboxylic acids such as tiglic acid and ungeric acid; addition-polymerizable unsaturated fatty dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, glitaconic acid and hydromuconic acid. Can be mentioned.

In order to form a crosslinked structure in such resin core material particles, a bifunctional or polyfunctional monomer is used. Examples of difunctional or polyfunctional monomers include ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri
(Meth) acrylate, 1,1,1-trishydroxymethylethanediacrylate, 1,1,1-trishydroxymethylethanetriacrylate, 1,1,1-trishydroxymethylpropane triacrylate and divinylbenzene are mentioned. it can.

In particular, it is preferable to use divinylbenzene as the difunctional or polyfunctional monomer. When the core material particles are formed of (meth) acrylic resin,
(Meth) acrylic acid ester monomer
To 100 parts by weight, preferably 40 to 100 parts by weight, a styrene-based monomer, usually 0 to less than 20 parts by weight,
A copolymer obtained by (co) polymerizing a vinyl monomer in an amount of preferably 0 to 15 parts by weight, usually 0 to 50 parts by weight, and an unsaturated carboxylic acid monomer in an amount of usually 0 to 50 parts by weight can be used.

When the core material particles are a styrene resin,
Styrene monomer, usually 20 to 100 parts by weight, preferably 40 to 100 parts by weight, (meth) acrylate monomer, usually 0 parts by weight or more and less than 20 parts by weight,
A copolymer obtained by (co) polymerizing a vinyl monomer in an amount of preferably 0 to 15 parts by weight, usually 0 to 50 parts by weight, and an unsaturated carboxylic acid monomer in an amount of usually 0 to 50 parts by weight can be used.

When the core particles are a copolymer of a (meth) acrylate monomer and a styrene monomer, the (meth) acrylate monomer is usually 20 to 80 parts by weight, preferably Is 40 to 60 parts by weight, the styrene monomer is usually 20 to 80 parts by weight, preferably 40 to 60 parts by weight, and the vinyl monomer is usually 0 to 5 parts by weight.
0 parts by weight of the unsaturated carboxylic acid monomer,
Copolymers (co) polymerized in parts by weight can be used.

Further, in order to form a crosslinked structure in such resin particles, it is preferable to use a bifunctional or polyfunctional monomer. Then, in order to make the compression breaking strength of the core material particles as in the present invention (the conductive particles are crushed when the compression load reaches a load value in the range of 2 gf / particle to 3 gf / particle). For this purpose, the amount of the bifunctional or polyfunctional monomer is adjusted to form a moderately crosslinked structure. Specifically, in order to achieve the above compressive breaking strength, a bifunctional or polyfunctional monomer is usually used in an amount of 0.1 to 50 parts by weight, preferably 1 to 20 parts by weight.

When preparing resin particles by suspension polymerization, by using inorganic particles having a particle diameter of 1 μm or less, preferably 0.5 μm or less as a protective colloid, spherical resin particles are usually provided with irregularities. be able to.

The above example is an example of a method for adjusting the compressive breaking strength of a single particle within a predetermined range, and is not limited to a method using such a bifunctional or polyfunctional monomer, but may be another method. Can also be adopted. For example, resin particles having a particle diameter of about 1/3 to 1/100 of the core particles used in the present invention are produced, and these are aggregated to produce aggregated particles having an average particle diameter of about 2 to 30 μm. Such agglomerated particles have their individual particles bonded together with a relatively weak engaging force such as an adsorbing force, and the internal compression breaking strength of such agglomerated particles is 4 kgf / mm ² or less, preferably 3 kgf / mm ² or less.
Particles up to mm ² can be used.

The hollow resin particles can have a low compressive breaking strength by, for example, reducing the thickness of the resin. Among the hollow resin particles, for example, by reducing the thickness of the resin, the compressive breaking strength can be reduced to 4 kgf / kg. Hollow resin particles adjusted to not more than mm ² , preferably not more than 3 kgf / mm ² can be used. Furthermore, in the case of such hollow resin particles, instead of adjusting the thickness of the resin, or while adjusting the thickness of the resin, the bifunctional or polyfunctional monomer is copolymerized as described above, so that the compression fracture is caused. The strength can also be adjusted.

As described above, when a compressive load is applied to the core particles 2 of the conductive particles 1, the compressive deformation rate sharply increases when the compressive deformation rate of the conductive particles is in the range of 5 to 40%. One having a compression deformation characteristic having an inflection point, in other words, a compression load of 1 gf / particle to 3 gf /
The particles have the characteristics of hard elastic spheres, but when the compression load reaches 1 gf / particle to 3 gf / particle,
A material having a compression deformation characteristic of crushing and plastically deforming can be used.

When the conductive particles 1 (core material particles 2) further have the above-mentioned compressive deformation characteristics, the anisotropic conductive adhesive containing the conductive particles 1 (anisotropic material) Conductive Film,
Even when the electrodes are electrically bonded by using an anisotropic conductive film), the electrodes or the substrate are not deformed or the electrodes or the substrate are not damaged.

FIG. 7 is a diagram showing a configuration example of the anisotropic conductive adhesive according to the present invention. In the example of FIG. 7, the anisotropic conductive adhesive 11 is configured as a film-like film (anisotropic conductive film, anisotropic conductive film). Referring to FIG. 7, the anisotropic conductive adhesive 11 has an insulating adhesive 12 in which conductive particles 1 are dispersed at a predetermined ratio.

Specifically, the conductive particles 1 are formed at such a density that the anisotropic conductive adhesive 11 can function as an anisotropic conductive adhesive (that is, the anisotropic conductive adhesive 11). For example, when two wiring boards each having a wiring pattern (conductive member) formed on the surface thereof are bonded together with the wiring patterns (conductive members) facing each other, Insulate between wiring patterns and ensure electrical conductivity between facing wiring patterns (securing insulation in the horizontal direction and ensuring conductivity only in the vertical direction)
(At such a density as to perform its function) in the insulating adhesive 12. More specifically, in the anisotropic conductive adhesive 11, the conductive particles 1 of the present invention are contained in the insulating adhesive 12 in an amount of 50 to 5000 particles / mm ² , preferably 100 to 3 particles.
000 particles / mm ² , more preferably 300 to 1000 particles / mm ² .

As the conductive particles 1 contained in the anisotropic conductive adhesive 11 of FIG. 7, the above-described conductive particles 1 of the present invention are used. That is, the conductive particles 1 contained in the anisotropic conductive adhesive 11 are electrically conductive because a plurality of conductive members (for example, wiring patterns) are conductively bonded using the anisotropic conductive adhesive 11. When a predetermined compressive load is applied to the anisotropic conductive adhesive 11 between the conductive members, the irregularities on the surface of the conductive particles 1 break through the coating of the insulating adhesive 12 and reach the conductive member. Is formed on

More specifically, the irregularities on the surface of the conductive particles 1 have a depth in the range of 0.05 to 2 μm, and the surface density of the irregularities is 1000 to 5 μm.
It is in the range of 00000 / mm ² .

Then, such surface irregularities are formed in the conductive layer 3 of the conductive particles 1.

The conductive particles 1 have an inflection point at which the compressive deformation rate rapidly increases when the compressive deformation rate of the conductive particles is in the range of 5 to 40% when a compressive load is applied. (At room temperature, a compression load of 2 gf / particle to 3 gf / particle has a characteristic as a hard elastic sphere up to a compression load of 2 gf / particle to 3 gf / particle.
When the particles reach the particles, they have a compressive deformation characteristic of crushing and plastically deforming).

More specifically, in the conductive particles 1, the core particles 2 are formed of a predetermined resin material, and the conductive layer 3 is formed of a predetermined metal material on the entire surface of the core particles 2. The conductive particles 1 are crushed and plastically deformed at a compressive load of 2 gf / particle to 3 gf / particle and have an inflection point at which the compressive deformation rate sharply increases. It is good that it has become.

That is, the conductive particles 1 having the above-mentioned compressive deformation characteristics are particles that are surely crushed when the anisotropic conductive adhesive 11 is heated and pressed between electrodes or the like. More specifically, core material particles 2 forming conductive particles 1 of the present invention
Is 10 to 30 kg / cm ² at a temperature of 120 to 170 ° C.
The pressure is preferably crushed by applying pressure for 1 to 10 seconds, and the form is preferably such that the form does not return to the original state even when the pressure is released.

The conductive particles 1 are usually 2 to 50 μm.
m, preferably 5 to 30 μm. Further, the CV value of the conductive particles 1 is preferably 20% or less, more preferably 15% or less. Here, the CV value is defined as an average value (average particle diameter) AV of each conductive particle 1 contained (dispersed) in the anisotropic conductive adhesive material 11 and the average particle size AV of each conductive particle 1. It means the ratio (σ / AV) to the standard deviation σ of the particle diameter, and the CV value of the conductive particles 1 contained in the anisotropic conductive adhesive 11 is
It is better to be as small as possible. That is, the conductive particles 1 used for the anisotropic conductive adhesive 11 preferably have the same particle diameter as much as possible.

In the anisotropic conductive adhesive 11 shown in FIG. 7, as the insulating adhesive 12, for example, a (meth) acrylic adhesive, an epoxy adhesive, a polyester adhesive,
Urethane-based adhesives and rubber-based adhesives can be used. In particular, in the present invention, it is preferable to use a (meth) acrylic resin adhesive.

Examples of the acrylic resin adhesive include:
Copolymers of (meth) acrylate and a compound having a reactive double bond copolymerizable therewith can be exemplified. Examples of the (meth) acrylate used here include methyl (meth) acrylate, ethyl (meth)
Acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl
(Meth) acrylate, cyclohexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, chloro-2-hydroxypropyl (meth) acrylate, diethylene glycol mono (meth) acrylate, methoxyethyl ( (Meth) acrylate, ethoxyethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate and glycidyl
(Meth) acrylates can be mentioned.

Examples of the compound having a reactive double bond copolymerizable with the (meth) acrylic ester as described above include unsaturated carboxylic acid monomers, styrene monomers and vinyl monomers. .

Here, examples of the unsaturated carboxylic acid monomer include acrylic acid, (meth) acrylic acid, α-ethylacrylic acid, crotonic acid, α-methylcrotonic acid, α-ethylcrotonic acid, isocrotonic acid, tiglin Addition-polymerizable unsaturated aliphatic monocarboxylic acids such as acid and ungeric acid; and addition-polymerizable unsaturated aliphatic dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, glutaconic acid and dihydromuconic acid. be able to.

Examples of the styrene monomer include:
Alkylstyrenes such as styrene, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene and octylstyrene; fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene And halogenated styrenes such as iodostyrene;
Nitrostyrene, acetylstyrene and methoxystyrene can be mentioned.

Further, examples of the vinyl monomer include:
Vinyl pyridine, vinyl pyrrolidone, vinyl carpazole, divinyl benzene, vinyl acetate and acrylonitrile; conjugated diene monomers such as butadiene, isoprene and chloroprene; vinyl halides such as vinyl chloride and vinyl bromide; and vinylidene halides such as vinylidene chloride. be able to.

The (meth) acrylic resin adhesive is
(Meth) acrylic acid ester usually 60 to 90 parts by weight,
It is produced by copolymerizing other monomers usually in an amount of 10 to 40 parts by weight.

[0084] Such an acrylic adhesive can be produced by a usual method. For example, it can be produced by dissolving or dispersing the above-mentioned monomer in an organic solvent, and reacting the solution or dispersion in a reactor substituted with an inert gas such as nitrogen gas. Examples of the organic solvent used herein include aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as n-hexane; esters such as ethyl acetate and butyl acetate;
Examples include aliphatic alcohols such as propyl alcohol and i-propyl alcohol, and ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone. In the above reaction, the organic solvent is usually used in an amount of 100 to 250 parts by weight based on 100 parts by weight of the (meth) acrylic resin adhesive forming raw material.

This reaction is carried out by heating in the presence of a polymerization initiator. Examples of the reaction initiator used here include azobisisobutyronitrile, benzoyl peroxide, di-tert-butyl peroxide, cumene hydroperoxide and the like. The polymerization initiator is used usually in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the raw material monomer.

In the polymerization reaction in an organic solvent as described above, the reaction solution is usually heated to 60 to 75 ° C.,
The reaction is performed for 10 hours, preferably for 4 to 8 hours. The weight average molecular weight of the (meth) acrylic resin adhesive thus produced is usually in the range of 100,000 to 1,000,000.

In such an acrylic adhesive, a thermoplastic resin such as an alkylphenol, terpene phenol, modified rosin, or xylene resin may be blended, or a reactive curable resin such as an epoxy resin may be blended. Further, a curing agent such as an imidazole compound of such a reaction curable resin can be blended.

In the anisotropic conductive adhesive 11 of the present invention, the conductive particles 1 are added to the insulating adhesive 12 as described above.
0-5000 pieces / mm ² , preferably 100-3000
Pieces / mm ² , more preferably 300 to 1000 pieces / mm ²
, It is possible to perform anisotropic conductive bonding.

Further, it is preferable to incorporate a filler into the insulating adhesive 12 used in the present invention. Here, as the filler, insulating inorganic particles are preferable. Examples of the filler include titanium oxide, silicon dioxide, calcium carbonate,
Mention may be made of calcium phosphate, aluminum oxide and antimony oxide. These insulating inorganic particles usually have an average particle size of 0.01 to 5 μm. These insulating inorganic particles can be used alone or in combination.

The insulating inorganic particles are usually 10 to 100 parts by weight, based on 100 parts by weight of the resin component in the adhesive.
It is preferably used in an amount of 50 to 80 parts by weight.

By mixing the insulating inorganic particles as the filler in the above-described amount, the fluidity of the adhesive 12 can be adjusted, and even if heated after bonding, the adhesive 12 flows backward to inhibit conductivity. Less. Further, for example, when the two substrates face each other and the conductive patterns are electrically bonded between the wiring patterns on each substrate, it is possible to prevent the adhesive 12 from protruding from the ends of the substrates. By using the silicon resin powder and / or silicon dioxide as described above, the bonding reliability and conduction reliability of the anisotropic conductive adhesive 11 of the present invention with respect to stress are improved.

As described above, the anisotropic conductive adhesive 1 of the present invention
1 (anisotropic conductive film, anisotropic conductive film) can be produced by mixing the above components.

Further, the anisotropic conductive adhesive 11 of the present invention
When this is configured as an anisotropic conductive film (film), the film
The thickness of the (sheet) is preferably in the range of 10 to 50 μm. In order to form the anisotropic conductive adhesive 11 of the present invention into a sheet, for example, a knife coater, a comma coater, a reverse roll coater, a gravure coater or the like can be used.

The sheet-shaped anisotropic conductive adhesive 11 of the present invention (that is, an anisotropic conductive film) can be used, for example, as shown in FIG. That is, FIG.
(a) and (b) schematically show examples of bonding a substrate using the anisotropic conductive film of the present invention.

In the example of FIGS. 8A and 8B, first, FIG.
As shown in the figure, a wiring pattern (conductive member) 19 is formed on the surface.
a and 19b are formed on the two substrates 18a and 18b,
The wiring patterns 19a and 19b are arranged so as to face each other, and the sheet-shaped anisotropic conductive adhesive 11 (anisotropic conductive film) of the present invention is sandwiched between the wiring patterns 19a and 19b. Note that this anisotropic conductive film 11
For example, the conductive particles 1 of the present invention are dispersed in an insulating adhesive 12 made of an acrylic adhesive, and a filler 16 is further dispersed.

The substrates 18a and 18b on which the anisotropic conductive films 11 are arranged are, for example, 30 to 100 kg at a temperature of 120 ° C. to 170 ° C. in the direction of the arrow shown in FIG.
When bonding is performed by applying pressure at a pressure of / cm ² , as shown in FIG. 8B, the conductive particles 1 between the wiring patterns 19a and 19b receive the highest pressure. At this time, even if the insulating adhesive 12 remains between the conductive particles 1 and the wiring patterns 19a and 19b, the irregularities on the surface of the conductive particles 1 may cause the conductive particles 1 to become uneven between the conductive particles and the conductive member. The wiring pattern 19a, 19b is reliably reached by removing the insulating adhesive interposed therebetween, whereby the conductive particles 1 and the wiring pattern 19 are removed.
a, 19b. At this time, when the conductive particles 1 between the wiring patterns 19a and 19b receive the highest pressure, the conductive particles 1 are crushed. The state where the conductive particles 1 are crushed is shown in more detail in FIG. In FIG. 9, 1b is a conductive particle that is not crushed, and 1a is a crushed conductive particle.

[0097] The pressure applied to the substrate during the thermocompression bonding is as follows:
Generally, the pressure is 30 to 100 kg / cm ² , but the conductive particles 1 are crushed by applying a pressure of, for example, 10 to 30 kg / cm ² . Then, in the portion where the wiring pattern is formed,
Wiring patterns 19a and 19 are formed by conductive particles 1a crushed by wiring patterns 19a and 19b.
b is conducted. On the other hand, since such pressure is not applied to the particles 1b in the portion where the wiring pattern is not formed, a good insulating property is exhibited. Thus, anisotropic conductive bonding can be performed.

In the above description, the embodiment in which the anisotropic conductive adhesive 11 of the present invention is used in the form of a sheet (in the form of an anisotropic conductive film) is used, but the anisotropic conductive adhesive 11 of the present invention is used. Can be used in a paste form by containing an appropriate solvent. This paste-shaped anisotropic conductive adhesive 11 can be used as an anisotropic anisotropic conductive adhesive in the same manner as described above, for example, by applying it on a substrate using a screen coater or the like. That is, the anisotropic conductive adhesive 11 of the present invention can be used in various forms such as a paste shape as well as a sheet shape (film shape).

As described above, the anisotropic conductive adhesive 1 of the present invention
1 has irregularities of sufficient depth and surface density formed on the surface of the conductive particles 1 contained therein, so that the anisotropic conductive adhesive 11 is used to connect a plurality of conductive members. When a predetermined compressive load is applied to the anisotropic conductive adhesive between the conductive members for conductive bonding, the surface of the conductive particles has irregularities interposed between the conductive particles and the conductive member. To reach the conductive member, whereby the conductive particles 1
A conductive connection can be reliably established between the conductive member and the conductive member.

Further, the anisotropic conductive adhesive 11 of the present invention
The conductive particles 1 contained therein have the characteristics of a hard elastic sphere as described above in the initial stage where the compressive load is relatively small, and when the compressive load increases to some extent, suddenly collapse, When it has the property of plastic deformation,
Crushing is performed at a pressure lower than the pressure applied during normal pressure bonding operation. Therefore, when using the anisotropic conductive adhesive material 11 to perform anisotropic conductive bonding on an electrode formed on a film liquid crystal and an electrode formed on a flexible printed board, these electrodes and the substrate may be deformed. No damage.

Therefore, the anisotropically conductive adhesive of the present invention has two hard glass substrates facing each other, and has an anisotropic conductive adhesive between the wiring patterns (conductive members) formed on the two glass substrates. Wiring patterns (conductive members) formed on two soft substrates by facing two soft (flexible) substrates, such as a resin film substrate, as well as being used when connecting. It can be suitably used even when anisotropically conductively bonding between the layers, and is particularly suitable for producing a liquid crystal display device using a polymer film as a substrate.

That is, in recent years, PDAs (Portable Information Terminals),
2. Description of the Related Art As a display serving as a man-machine interface in a portable device such as a mobile phone, a liquid crystal display device using a polymer film having a thin, lightweight, non-breakable characteristic as a substrate has attracted attention. FIG. 8 is a schematic plan view showing an example of this type of liquid crystal display device (liquid crystal display device).
FIG. 9 is a sectional view taken along line AA of FIG. 8.

Referring to FIGS. 10 and 11, a stripe-shaped ITO electrode (wiring pattern) 2 formed at a constant interval is formed on the surface of the first polymer film substrate 21.
2 and an alignment film 23 are formed. On the back surface of the first polymer film substrate 21, a polarizing plate 24, a reflecting plate 25
Are sequentially formed. On the surface of the second polymer film substrate 31 are formed stripe-shaped ITO electrodes (wiring patterns) 32 formed at regular intervals and an alignment film 33.
A polarizing plate 34 is formed on the back surface of the.

Here, the first polymer film substrate 2
The first polymer film substrate 31 is made of, for example, polycarbonate (PC), polyether sulfone (PE).
S) or a material such as polysulfone (PS) with a thickness of, for example, 0.1 to 0.2 mm.

Further, a sealing material 26 is provided on the surface of the first polymer film substrate 21, and a predetermined distance is provided on the surface of the second polymer film substrate 31 (on the surface of the alignment film 33). , A gap material (spacer) 35 is disposed.

Here, the first polymer film substrate 21 and the ITO film formed on the substrate 21 are formed.
The electrode 22, the alignment film 23, the sealing material 26, the polarizing plate 24, and the reflecting plate 25 are collectively referred to as a lower substrate 20, and a second polymer film substrate 31,
The ITO electrode 32, the alignment film 33, the gap material 35, and the polarizing plate 34 formed on the substrate are collectively referred to as an upper substrate 30.

In the examples shown in FIGS. 10 and 11, the lower substrate 20 and the upper substrate 30 are connected in such a manner that the wiring pattern of the ITO electrode 22 and the wiring pattern of the ITO electrode 32 are orthogonal to each other. Part of electrode 22, ITO
Face-to-face (facing) so that a part of the electrode 32 is exposed
Then, they are heat-pressed to form a substrate for a liquid crystal display element. That is, the lower substrate 20 and the upper substrate 30 face each other at an interval determined by the thickness of the gap material (spacer) 35, and the lower substrate 20 and the upper substrate 30
The lower substrate 20 and the upper substrate 30 are exposed in such a manner that a part of the ITO electrode 22 and a part of the ITO electrode 32 are exposed.
Of the sealing material 2 except for the liquid crystal injection part 40.
6 to form a substrate for a liquid crystal display element.

In such a liquid crystal display substrate, a liquid crystal material is injected from a liquid crystal injection portion 40 into a gap separated by a gap material 35 between the lower substrate 20 and the upper substrate 30, and thereafter, the liquid crystal injection is performed. By sealing the portion 40 with a sealing agent, this can be manufactured as a liquid crystal display element.

In the liquid crystal display device thus manufactured,
Striped ITO electrode 22 and striped ITO
The intersection with the electrode 23 (intersection of the wiring pattern) can function as one dot on the liquid crystal display screen. That is, by applying a predetermined drive signal to each of the exposed portions of the ITO electrode 22 and the ITO electrode 32,
By changing the alignment state of the liquid crystal at the intersection of the TO electrode 22 and the ITO electrode 32, predetermined characters and figures can be displayed on this screen when viewed from the upper substrate 30 side.

In other words, in the configuration examples shown in FIGS. 10 and 11, the portion of the ITO electrode 22 exposed on the lower substrate 20 and the portion of the ITO electrode 32
Function as an external lead-out wiring electrode (lower electrode lead-out part) 42 and an external lead-out wiring electrode (upper electrode lead-out part) 43, respectively. The display can be performed by providing the driving signals. For this reason,
The external lead-out wiring electrode (lower electrode lead-out part) 42 and the external lead-out wiring electrode (upper electrode lead-out part) 43
Usually, flexible wiring electrode terminals for drive circuit devices are connected by thermocompression bonding. That is, the electrode terminals on the drive circuit board are connected by thermocompression bonding.

In the configuration examples shown in FIGS. 10 and 11, so-called double-sided electrode extraction is provided in which wiring electrodes (electrode extraction portions) 42 and 43 for external extraction are provided on the lower substrate 20 and the upper substrate 30, respectively. Although it is of a model type, it is also possible to adopt a configuration in which both the external lead-out wiring electrodes (electrode take-out portions) 42 and 43 are provided only on either the lower substrate 20 or the upper substrate 30 ( That is, a so-called one-sided electrode extraction type may be used.

FIG. 12 is a schematic plan view showing an example of a liquid crystal display element (liquid crystal display device) of the one-sided electrode extraction type, and FIG. 13 is a sectional view taken along line BB of FIG. In the case of the one-side electrode extraction type as shown in FIG. 12, for example, the wiring pattern of the striped ITO electrode 22 on the lower substrate 20 is changed to the striped ITO electrode on the upper substrate 30 immediately before the sealing material 26, for example. It is bent at a right angle so as to be parallel to the wiring pattern of the electrode 32, and the IT
This wiring pattern of the O electrode 22 is extended on the upper substrate 30 via upper and lower conductive portions (through holes) 29 formed in the sealing material 26 (see FIG. 13). The wiring is exposed together with the wiring pattern of the electrode 32 to form a wiring electrode (electrode extraction portion) 42 for external drawing.
Can be configured as That is, the upper substrate 30
On the top, a wiring electrode for external extraction (electrode extraction portion) 42,
43 can be provided.

Incidentally, even in the case of the two-sided electrode take-out type as shown in FIGS.
As described above, even the one-sided electrode take-out type electrodes such as 3, the external lead-out wiring electrodes (electrode take-out portions) 42 and 43 are usually provided with flexible wiring electrode terminals for drive circuit devices (that is, The electrode terminals on the drive circuit board are connected by thermocompression bonding. To perform this thermocompression connection, the anisotropic conductive adhesive of the present invention described above (anisotropic conductive film)
11 can be used.

FIG. 14 shows an anisotropic conductive connection according to the present invention in which a thermocompression connection between a wiring electrode for external drawing (conductive member) of a substrate for a liquid crystal display element and a flexible wiring electrode terminal (conductive member) for a drive circuit device is performed. FIG. 3 is a diagram showing an example of a method performed using a conductive adhesive (anisotropic conductive film) 11. In FIG. 14,
In the liquid crystal display element of the double-sided electrode extraction type as shown in FIGS. The case of crimping connection is shown. In the example of FIG. 14, the separator 60 is attached to the anisotropic conductive adhesive (anisotropic conductive film) 11 in advance.

Referring to FIG. 14, first, the lower substrate 20
Upper external wiring electrode (lower electrode extraction portion) 42
On top, the anisotropic conductive adhesive (anisotropic conductive film) 11 of the present invention is placed, and for example, at a temperature of 60 ° C. to 80 ° C., the anisotropic conductive adhesive (anisotropic conductive film) 11 Thermocompression bonding to external lead-out wiring electrode (lower electrode take-out part) 42 on lower substrate 20
(FIG. 14 (a)). At this time, the separator 60 is separated from the anisotropic conductive adhesive (anisotropic conductive film) 11.

Thereafter, the drive circuit board is placed on the external lead-out wiring electrode (lower electrode extraction portion) 42 on the lower substrate 20 via the anisotropic conductive adhesive (anisotropic conductive film) 11. The electrode terminal 52 on the position 51 is positioned (FIG. 14B).
After such positioning, the drive circuit board 51 is thermocompression-bonded to the lower substrate 20 via the anisotropic conductive adhesive (anisotropic conductive film) 11 (FIG. 14C). In addition, this thermocompression bonding process can be performed in two stages, that is, a temporary process and a main process.
(Preferably about 130 ° C.) at a pressure of 2-4 MPa (preferably about 3 MPa) for about 5-15 seconds (preferably about 10
Seconds).

By such a thermocompression bonding process, the anisotropic conductive adhesive (anisotropic conductive film) 11 between the lower substrate 20 and the drive circuit substrate 51 is shown in FIGS. 8B and 9. The state is the same as described above. That is, in the portion where the external lead-out wiring electrode 42 on the lower substrate 20 and the electrode terminal 52 on the drive circuit board 51 exist, the external lead-out wiring electrode 42 on the lower substrate 20 and the drive circuit board 51 The conductive particles 1 a crushed by the electrode terminals 52 conduct the electrical connection between the external lead-out wiring electrodes 42 on the lower substrate 20 and the electrode terminals 52 on the drive circuit board 51. On the other hand, such pressure is not applied to the particles 1b in the portion where the external lead-out wiring electrode 42 on the lower substrate 20 and the electrode terminal 52 on the drive circuit substrate 51 do not exist, so that good insulation is exhibited. Thus, anisotropic conductive bonding can be performed.

In the present invention, since the anisotropic conductive adhesive 11 has irregularities of sufficient depth and surface density formed on the surface of the conductive particles 1 contained therein, Anisotropic conductive adhesive 11 between electrodes 42 and 52 for conductively bonding between electrodes 42 and 52 using conductive adhesive 11
When a predetermined compressive load is applied to the electrode 4, the irregularities 6 on the surface of the conductive particles 1 break through the coating of the insulating adhesive 12 and
2,52, whereby the conductive particles 1 and the electrodes 4
Conductive connection can be reliably established between the first and second members.

In the present invention, the anisotropic conductive adhesive 11
Conductive particles 1 contained in the compression deformation characteristics C ₁ in FIG. 5
Compressive deformation characteristics such as (In the initial stage where the compressive load is relatively small, it has the characteristics as a hard elastic sphere as described above, and when the compressive load increases to some extent, it suddenly collapses,
(A property of plastic deformation), it is crushed at a pressure lower than the pressure applied at the time of a normal pressure bonding operation.
Specifically, the external lead-out wiring electrode 4 on the lower substrate 20
2, when the electrode terminals 52 on the drive circuit board 51 are thermocompression-bonded via an anisotropic conductive adhesive (anisotropic conductive film) 11, the conductive property of the anisotropic conductive adhesive during thermocompression bonding is reduced. The compressive deformation rate of the conductive particles is about 20 to 80%.

FIGS. 15 (a), 15 (b) and 15 (c) show external parts on the lower substrate 20 using the conductive particles having the compressive deformation characteristics C ₁ , C ₂ and C ₃ of FIG. Leading wiring electrode 42
The schematic diagram shows the case where conductive bonding is performed between the electrode terminal 52 on the drive circuit board 51 and the electrode terminal 52 on the drive circuit board 51. Note that FIG.
In the examples of (a), (b) and (c), as shown in FIGS. 4 (a) and 4 (b), the case where conductive particles having little unevenness on the surface are used is shown.

As described above, the conventional conductive particles having a compressive deformation characteristic of C ₂ have a large amount of compressive deformation and a large compressive deformation ratio with respect to a compressive load as described above (ie, as a soft elastic sphere). Properties),
As shown in FIG. 15B, the external lead-out wiring electrode 42 on the lower substrate 20 and the electrode terminal 52 on the drive circuit substrate 51
When thermocompression bonding is performed between the conductive particles 1 and the conductive particles 1, the conductive particles are easily deformed, and the wiring electrodes 42 for external extraction on the lower substrate 20, the electrode terminals 52 on the drive circuit board 51, and the conductive particles 1 In between, the insulating adhesive (binder) 12 is left (the conductive particles 1 are connected to the external lead-out wiring electrode 42 on the lower substrate 20 and the electrode terminal 52 on the drive circuit board 51).
), And good conductive adhesion cannot be achieved.

Further, as described above, the conventional conductive particles having a compressive deformation characteristic of C _{3 have} an amount of compressive deformation with respect to a compressive load,
Although the compressive deformation rate has a small characteristic (that is, it has the characteristics of a hard elastic sphere), since the characteristics of this hard elastic sphere are maintained within a range where the compressive load is considerably large, As shown in FIG. 15C, the external lead-out wiring electrode 42 on the lower substrate 20 and the drive circuit substrate 5
When the thermocompression bonding is performed between the electrode terminal 52 and the upper electrode 1, the hard conductive particles 1 do not crush and deform or damage the substrate 20 and the electrodes 42 and 52 until the compression load becomes considerably large. (For example, cracks may occur in the ITO electrode).

On the other hand, as shown in FIG. 15A, the conductive particles 1 having the compression deformation characteristic of C ₁ are connected to the external lead-out wiring electrode (lower electrode extraction portion) 42 on the lower substrate 20. When performing thermocompression bonding with a flexible wiring electrode terminal for a drive circuit device (that is, the electrode terminal 52 on the drive circuit board 51), the rate at which the conductive particles 1 directly contact the electrode due to the initial hardness. At this stage, the conductive particles 1 are crushed and the substrate 2
0 and the electrodes 42 and 52 are not deformed or damaged, and the crushing causes the contact area between the conductive particles 1 and the electrodes 42 and 52 without deforming or damaging the substrate 20 and the electrodes 42 and 52. Can be increased.

As described above, by using the conductive particles 1 having the compression deformation characteristic of C ₁ and the anisotropic conductive adhesive (anisotropic conductive film) 11 using the conductive particles, the external drawing on the lower substrate 20 can be performed. Conductive bonding between the wiring electrodes 42 for use and the electrode terminals 52 on the drive circuit board 51 can be performed extremely reliably.

However, in the present invention, in order to ensure the conductive bonding between the external lead-out wiring electrode 42 on the lower substrate 20 and the electrode terminal 52 on the drive circuit board 51, the minimum condition is as follows. When a predetermined compressive load is applied to the anisotropic conductive adhesive 11 between the external lead-out wiring electrode 42 on the lower substrate 20 and the electrode terminal 52 on the drive circuit board 51, the surface of the conductive particles 1 It is sufficient that the conductive particles 1 have such a feature that the irregularities are formed to such an extent that they penetrate the coating of the insulating adhesive 12 and reach the electrodes 42 and 52. Further having the compression deformation characteristic of C ₁ is an incidental condition. For example, if those also of compressive deformation characteristics of the conductive particles 1 is C _2, when the conductive particles 1 of the surface irregularities as described above is not formed, unevenness of the conductive particles 1 of the surface Breaks through the coating of the insulating adhesive 12 and
2, 52, so that the conductive connection between the external lead-out wiring electrode 42 on the lower substrate 20 and the electrode terminal 52 on the drive circuit board 51 can be made to some extent.

Further, the anisotropic conductive adhesive (anisotropic conductive film) 11 of the present invention is connected to, for example, an external lead-out wiring electrode (lower electrode extraction portion) 42 on the lower substrate 20 and a drive circuit device. When used for anisotropic conductive bonding with a flexible wiring electrode terminal (that is, the electrode terminal 52 on the drive circuit board 51), the anisotropic conductive adhesive (anisotropic conductive film) 1 of the present invention is used.
As shown in FIG. 14, No. 1 can be configured such that the relationship between the particle diameter D of the conductive particles 1 and the film thickness T of the insulating adhesive (binder) 12 satisfies D ≧ T.

More specifically, the insulating adhesive (binder) 1
The thickness T of the electrode terminal 5 on the lower circuit board 20 and the electrode terminal 5 on the drive circuit board 51 at the time of thermocompression bonding.
2 is almost completely filled with the anisotropic conductive adhesive (anisotropic conductive film) 11 of the present invention, and the excess adhesive
It is preferable that the (binder) 12 does not overflow from between the lower substrate 20 and the drive circuit substrate 51.

As described above, the relationship between the particle diameter D of the conductive particles 1 and the film thickness T of the insulating adhesive (binder) 12 is such that D ≧ T. (Binder) 1 between the conductive particles 1 and the electrodes 42 and 52
2 can be further reduced, and the anisotropic conductive bonding between the lower substrate 20 and the electrode terminals 52 on the drive circuit substrate 51 can be more reliably performed. Furthermore, in this case,
At the time of thermocompression bonding, excess adhesive (binder) 12 can be prevented from overflowing the substrate.

As described above, according to the present invention, since the surface of the conductive particles 1 contained in the anisotropic conductive adhesive 11 is formed with irregularities of sufficient depth and surface density, When a predetermined compressive load is applied to the anisotropic conductive adhesive between the conductive members to electrically conductively bond the plurality of conductive members using the conductive adhesive 11, the irregularities on the surface of the conductive particles may become conductive. The insulating adhesive intervening between the particles and the conductive member is eliminated to reach the conductive member, whereby the conductive particles 1
A conductive connection can be reliably established between the conductive member and the conductive member.

Further, the conductive particles 1 contained in the anisotropic conductive adhesive 11 have the characteristics as hard elastic spheres as described above at the initial stage when the compressive load is relatively small. The rate at which the insulating adhesive (binder) 12 remains between the conductive particles 1 and the external lead-out wiring electrodes 42 on the lower substrate 20 and between the electrode terminals 52 on the drive circuit substrate 51 and the conductive particles 1 is significantly reduced. Through the conductive particles 1, conduction between the external lead-out wiring electrode 42 on the lower substrate 20 and the electrode terminal 52 on the drive circuit board 51 can be reliably ensured. In addition, the conductive particles 1 of the present invention have the property of suddenly crushing and plastically deforming after the initial stage where the compressive load is relatively small, so that the substrate 20 is made of a soft material such as a polymer film. Even if the substrate 20 or the electrodes 42, 52
They do not deform or damage. Then, the conductive particles 1 are crushed and plastically deformed at a stage after the initial stage where the compressive load is relatively small, so that the substrate 20
The contact area of the conductive particles 1 with the electrodes 42 and 52 can be increased without deforming or damaging the electrodes 42 and 52. As a result, the resistance (contact resistance) via the conductive particles 1 between the external lead-out wiring electrode 42 on the lower substrate 20 and the electrode terminal 52 on the drive circuit substrate 51 can be reduced.

That is, by using the anisotropic conductive adhesive 11 containing the conductive particles 1 of the present invention, the conductive particles 1
The surface irregularities eliminate the insulating adhesive interposed between the conductive particles and the conductive member to ensure conductive connection with the conductive member, and furthermore, the contact area between the electrode and the conductive particle is reduced. In addition to the above, cracking of the ITO electrode on the polymer film substrate in contact with the conductive particles can be significantly reduced. Also, from this, the pitch (I
Even in the case of a fine wiring pattern having a pitch of about 200 μm (TO electrode pitch), anisotropic conductive bonding between the lower substrate 20 and the electrode terminals 52 on the drive circuit substrate 51 is performed with high reliability. It becomes possible.

In the above-described example, in the liquid crystal display device of the double-sided electrode extraction type as shown in FIGS. 10 and 11, the external lead-out wiring electrode (lower electrode extraction portion) 42 on the lower substrate 20 and the driving circuit Flexible wiring electrode terminals for devices (that is, electrode terminals 5 on drive circuit board 51)
2) is described in connection with thermocompression bonding.
In the liquid crystal display element of the double-sided electrode extraction type as shown in FIG.
(Lower electrode take-out part) 43, when a flexible wiring electrode terminal for a drive circuit device (that is, an electrode terminal on a drive circuit board) is thermocompression-bonded to the lower electrode extraction portion 43, it can be performed in the same manner as described above. Yes, and Figure 12,
In a liquid crystal display element of a one-sided electrode extraction type as shown in FIG. 13, for example, flexible wiring electrode terminals for a drive circuit device (ie, external wiring lines (lower electrode extraction portions) 42 and 43 on the upper substrate 30). When connecting the electrode terminals on the drive circuit board by thermocompression bonding,
This can be done in exactly the same way as described above.

As described above, by using the conductive particles 1 of the present invention and the anisotropic conductive adhesive 11 containing the conductive particles 1, for example, an electrode formed on a film liquid crystal or a flexible printed board is formed. When performing anisotropic conductive bonding on the electrode, reliable conductive bonding can be performed without deforming or damaging the electrode or the substrate.

[0134]

As described above, according to the first to ninth aspects of the present invention, conductive particles are contained in an insulating adhesive to form an anisotropic conductive adhesive. When a predetermined compressive load is applied to the anisotropic conductive adhesive between the conductive members in order to conductively bond the plurality of conductive members using the conductive adhesive, the irregularities on the surface of the conductive particles may become conductive particles. The conductive connection between the conductive particles and the conductive member is formed so as to be sufficient to reach the conductive member by eliminating the insulating adhesive interposed between the conductive particles and the conductive member. Can be reliably ensured.

Further, in the present invention, the conductive particles
In the initial stage where the compressive load is relatively small, it has the characteristics of a hard elastic sphere, and after the initial stage where the compressive load is relatively small, it suddenly collapses and has the property of plastic deformation. Using an anisotropic conductive adhesive containing the conductive particles, for example, a wiring electrode for external drawing (lower electrode extraction part) on a soft substrate such as a polymer film and a flexible wiring electrode for a drive circuit device Even in the case where anisotropic conductive bonding is performed between the terminal and the terminal, the anisotropic conductive bonding can be achieved with high reliability without deforming or damaging the substrate or the electrode.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a conductive particle according to the present invention.

FIG. 2 is a diagram showing a more specific configuration example of a conductive particle according to the present invention.

FIGS. 3A and 3B are diagrams showing a halftone image obtained by photographing the conductive particles of the present invention. FIGS.

FIG. 4 shows conventional conductive particles (conductive particles having almost no irregularities on the surface) for comparison with the conductive particles 1 of FIGS. 3 (a) and 3 (b).
FIG. 4 is a diagram showing a halftone image obtained by photographing a.

[5] compressive deformation characteristics C ₂ or C ₃ of the compressive deformation characteristics C ₁ of the conductive particles 1 of the present invention conventional general conductive particles
It is a figure which shows roughly by contrasting with FIG.

FIG. 6 is a diagram illustrating a state of conductive particles before applying a compression weight F and a state of the conductive particles when a compression weight F is applied.

FIG. 7 is a diagram showing a configuration example of an anisotropic conductive adhesive according to the present invention.

FIG. 8 is a view schematically showing a bonding method using the anisotropic conductive adhesive of the present invention.

FIG. 9 is an enlarged view of an electrode portion bonded using the anisotropic conductive adhesive of the present invention.

FIG. 10 is a schematic plan view illustrating an example of a liquid crystal display device (liquid crystal display device).

FIG. 11 is a sectional view taken along line AA of FIG. 10;

FIG. 12 is a schematic plan view showing another example of the liquid crystal display device (liquid crystal display device).

13 is a sectional view taken along line BB of FIG.

FIG. 14 is a diagram showing an example of a method of performing thermocompression bonding between an external lead-out wiring electrode of a liquid crystal display element substrate and a flexible wiring electrode terminal for a drive circuit device using the anisotropic conductive adhesive of the present invention. It is.

FIG. 15 shows a method of forming a conductive wiring between the external lead-out wiring electrode on the substrate and the flexible wiring electrode terminal for the driving circuit device by using the conductive particles having the compression deformation characteristics C ₁ , C ₂ , and C ₃ of FIG. 5; It is a figure showing the outline at the time of performing conductive adhesion.

FIG. 16 is a view showing another configuration example of the anisotropic conductive adhesive according to the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 conductive particles 2 core material particles 3 conductive layer 11 anisotropic conductive adhesive 12 insulating adhesive 16 filler 20 lower substrate 30 upper substrate 21 first polymer film substrate 31 second polymer film substrate 22, 32 ITO electrode 23, 33 Alignment film 24, 34 Polarizer 25 Reflector 26 Sealant 35 Gap material 42 External lead-out wiring electrode (lower electrode lead-out part) 43 External lead-out wiring electrode (upper electrode lead-out part) 51 Drive circuit board 52 electrode terminals

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H05K 1/14 H05K 1/14 C // B22F 1/02 B22F 1/02 A (72) Inventor Ikumi Sakata Saitama-shi, Saitama Hirose 130 Soken Chemical Stock Company In-house

Claims (9)

[Claims] 1. An electrically conductive particle having irregularities on its surface, wherein said electrically conductive particle is contained in an insulating adhesive to form an anisotropically conductive adhesive. When a predetermined compressive load is applied to the anisotropic conductive adhesive between the conductive members in order to conductively bond the plurality of conductive members, irregularities on the surface of the conductive particles may be generated between the conductive particles and the conductive member. The conductive particles are formed in a size sufficient to reach the conductive member by removing the insulating adhesive interposed therebetween. 2. The conductive particles according to claim 1, wherein the irregularities on the surface of the conductive particles have a depth of 0.05 to 2.
The conductive particles are in the range of μm, and the surface density of the projections and depressions is in the range of 1,000 to 500,000 particles / mm ² . 3. The conductive particles according to claim 1, wherein the conductive particles are obtained by forming a conductive layer on the surface of core material particles. The conductive particles, wherein the unevenness is defined by unevenness of a conductive layer. 4. The conductive particles according to claim 1, wherein a compressive load is 2 g at normal temperature.
f / particles to 3 gf / particles have properties as hard elastic spheres, and are crushed and plastically deformed when the compression load reaches 2 gf / particles to 3 gf / particles. particle. 5. An anisotropic conductive adhesive characterized in that the conductive particles according to claim 1 are dispersed in an insulating adhesive at a predetermined ratio. . 6. The anisotropically conductive adhesive according to claim 5, wherein the anisotropically conductive adhesive is formed as a film-like film. An anisotropic conductive adhesive, wherein the relation with the thickness T of the adhesive is D ≧ T. 7. The anisotropic conductive adhesive according to claim 5, wherein the average particle diameter of the conductive particles dispersed in the insulating adhesive is in a range of 2 μm to 30 μm, and An anisotropic conductive adhesive, wherein the conductive particles have a CV value of 20% or less. 8. The anisotropic conductive material according to claim 5, wherein the wiring electrode for external drawing of the liquid crystal display element using the resin substrate and the flexible wiring electrode terminal for a predetermined device are provided. An anisotropically conductive adhesive, wherein when subjected to thermocompression bonding using an adhesive, a compression deformation rate of conductive particles of the anisotropically conductive adhesive during thermocompression bonding is 20 to 80%. 9. The anisotropic conductive material according to claim 5, wherein a wiring electrode for external drawing of a liquid crystal display element using a resin substrate and a flexible wiring electrode terminal for a predetermined device are provided. A liquid crystal display device which is connected by thermocompression bonding using an adhesive.