JP2001202830A - Anisotropy conductive film and electrical connection body using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that when an anisotropy conductive film using metal plating resin particle as conductive particle is pressed between a substrate electrode and a connection electrode, plated metal components get stripped off from surface of particle and reliability is reduced. SOLUTION: An anisotropy conductive film has a flexible film, an organic binder and conductive particles. In the anisotropy conductive film, conductive particle includes core nucleus [m] of metal alloy having a high melting point and outer layers of the core nucleus, layer [m+1]... layer [m+n] from the core nucleus to the outside sequentially. If melting points of the core nucleus and the other layers are expressed as (m)mp, (m+1)mp, ...(m+n)mp, melting points of the core nucleus and each layer are (m)mp>(m+1)mp>...>(m+n)mp, an organic binder contains 0.05-300 weight part with respect to conductive particle 1 weight part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anisotropic conductive film using conductive particles and an electrical connection using the same. A liquid crystal panel, a liquid crystal television, a liquid crystal video camera, a thermal head, a solar cell, a calculator, a family computer, a hybrid IC conductor in which a flexible film having a drive IC circuit is directly bonded to a terminal electrode (for example, TAB (Tape Automated Bonding)). It can be applied to the mounting of a circuit board, a printed circuit board, an outer layer chip of a multilayer board for low-temperature firing, and a connection of a flexible printed board to a conductive circuit board.

[0002]

2. Description of the Related Art In recent years, as the density and color of liquid crystal panels and the like have been increased, connection of a driving IC circuit to the panel has become an important factor. Conventionally, IC or LS on printed wiring boards and liquid crystal panel electrodes, insulating film
I. A conductive circuit formed and mounted (for example, TAB (Tape
(Automated Bonding)), there is a method of directly connecting a connection electrode (TAB film external connection lead) on an insulating film by soldering, or a method of connecting conductive particles dispersed in an organic binder.

[0003] The conductive particles used for these are several μm
Particles obtained by plating gold or nickel on the surface of resin particles of polyethylene, polypropylene, polystyrene, or the like (for example, Japanese Patent Application Laid-Open No. H4-2242010), solder powder, and nickel have been used. As the organic binder, a known thermosetting or thermoplastic resin such as an epoxy resin, a urethane resin, a styrene butadiene resin, and a butyral resin has been used.

In the case of an anisotropic conductive film, a film having a thickness of 10 to 40 μm, a width of 2 to 6 mm, and a length of several m to several tens m in which conductive particles are dispersed in an organic binder is generally used. Publicly known. Connection by anisotropic conductive film
For example, in the case of a liquid crystal panel, an extraction electrode (several to several tens lines / mm: <pitch several hundred μm>) on the liquid crystal panel side
A film for anisotropic conductive connection is stuck on top, 50 to 12
Lightly adhere at a temperature of about 0 ° C. and a pressure of about 0.1 to 7 MPa. At this time, a guide tape of tetrafluoroethylene, polyethylene, polypropylene, polyethylene terephthalate, etc. is attached to the anisotropic conductive film or cured so that it can be easily handled on the anisotropic conductive film, and the liquid crystal panel side or flexible After bonding to the insulating film side, the guide tape is also peeled off.

After connecting the anisotropic conductive film, the driving IC
A connection electrode of an insulating film (e.g., a polyimide film) on which a circuit is mounted is positioned and pressed toward an opposite panel electrode (substrate electrode), and is pressed at a temperature of about 50 to 230 ° C. and a pressure of about 0.1 to 18 MPa. Connecting.
In this case, the conductive particles in the anisotropic conductive film present between the connection electrode of the insulating film and the liquid crystal panel electrode (substrate electrode) have contact points at both the connection electrode of the insulating film and the panel electrode (deformable ones). There is also an electrical connection between the circuit on the insulating film and the liquid crystal panel.

At this time, it is manufactured by controlling the amount and diameter of conductive particles in the anisotropic conductive film so that there is no electrical connection between adjacent substrate electrodes or connection electrodes. On the other hand, if there is an electrical connection between adjacent electrodes, the liquid crystal element (liquid crystal matrix) does not operate or an erroneous display occurs. As the substrate electrode on the liquid crystal panel side, there is generally an ITO electrode (indium-tin oxide) or the like, and those formed on a glass substrate by coating, sputtering or vapor deposition are known. In addition, aluminum, tin-plated copper, and the like are mainly used as connection electrodes of the insulating film.

[0007]

The conductive particles used in the anisotropic conductive film have the following problems. In other words, when plating particles such as gold-plated resin particles and nickel-plated resin particles are used, when pressurized between the substrate electrode and the insulating film connection electrode, the plated metal components gold and nickel become resin particles. Peel off from the surface. Although many of the particles are deformed when pressure is applied, in particular, the gold plating layer and the nickel plating layer are severely peeled off, making it difficult to secure conduction between the electrodes. Further, in the case of plating, it may be difficult to completely cover the surface of the resin particles, or the plating may come off from the surface of the particles when dispersed in an organic binder when producing an anisotropic conductive film. I also have problems.

[0008] In particular, as an essential disadvantage, in the flow of high density and fine pitch between electrodes, the number of conductive particles existing between the connection electrode and the substrate electrode is reduced, and the conductivity is reduced by resin particles. There is only a plating metal component on the surface, and sufficient conductivity cannot be ensured. In the case of using known metal or alloy particles, nickel and solder powder are known, but in the case of nickel, a nickel oxide insulating film is easily formed on the nickel surface, and the contact has a high resistance value.

In addition, even when pressure is applied, metal or alloy particles are not easily deformed, and it is difficult to obtain a contact area with an electrode. When a solder powder is used, it is easily deformed and a contact is easily obtained, but tin oxide is easily formed on the surface and the contact resistance increases. In addition, the effects of lead alpha radiation on the human body,
Malfunction of an LSI chip or the like is one of the important drawbacks. When copper powder is used, environmental resistance at the contact point is poor, and the resistance value between the electrodes increases. In the case of using silver powder, a problem of migration of silver occurs when the distance between adjacent electrodes is reduced to several tens of μm, and a short circuit between adjacent electrodes easily occurs.
Further, silver is soft, and when heated and pressurized, deformation is rather likely to occur, and connection resistance increases.

[0010]

Means for Solving the Problems In order to solve the above problems, it has been found that the conductive particles are defined as follows, and the present invention has been accomplished. That is,
The anisotropic conductive film according to claim 1 is an anisotropic conductive film having a flexible film, an organic binder, and conductive particles, wherein the conductive particles are a central core of a metal alloy having a high melting point [ m], and [m + 1] layers and [m +
2] layer: composed of an [m + n] layer and having a melting point of (m) mp, (m + 1) mp, (m +
2) When expressed as mp (m + n) mp, the melting point of the central core and each layer is (m) mp> (m + 1) mp> (m + 2) m
p ...> (m + n) mp, wherein the organic binder is contained in an amount of 0.05 to 300 parts by weight based on 1 part by weight of the conductive particles.

Further, in the anisotropic conductive film according to claim 2, in the anisotropic conductive film according to claim 1, the metal constituting the conductive particles is three or more, and the layers other than the outermost layer are An alloy layer with the central core [m], wherein the outermost layer [m + n] is a tin or tin alloy layer. The anisotropic conductive film according to claim 3 is the anisotropic conductive film according to claim 1 or 2, wherein the conductive particles have an average particle diameter of 2.5 to 40 μm and an average particle diameter of ± 2 μm particles. It is characterized in that the content occupies 80% by volume or more and the oxygen content is 5000 ppm or less.

According to a fourth aspect of the present invention, there is provided the anisotropically conductive film according to any one of the first to third aspects, wherein the metal constituting the conductive particles is gold, silver, copper, tin, bismuth, or zinc. , Nickel, palladium, chromium, indium, antimony, aluminum, germanium, silicon, beryllium, tungsten, molybdenum, manganese, tantalum, titanium, neodymium, and magnesium.

According to a fifth aspect of the present invention, there is provided the anisotropic conductive film according to any one of the first to fourth aspects, wherein the metal particles of the central nucleus [m] of the conductive particles are of the general formula AgxCuy [0]. .001 ≦ x ≦ 0.4, 0.6 ≦ y ≦
0.999, x + y = 1 (atomic ratio)], the average particle diameter is 2.5 to 35 μm, the average particle diameter is ± 2 μm, the content of the particles occupies 80% by volume or more, and the oxygen content is 5000 p.
pm or less, and the Ag concentration on the surface of the central core particle is higher than the average Ag concentration of the particles, and the surface of the central core particle has a fine uneven shape (the difference in height between the convex portion and the concave portion is 1 μm or less). It is characterized by the following.

The anisotropic conductive film according to claim 6 is the anisotropic conductive film according to claims 1 to 5, wherein the organic binder is a thermosetting resin, a thermoplastic resin, a photocurable resin, It is characterized by containing one or more resins selected from a line-curable resin and a photo-thermosetting resin. According to a seventh aspect of the present invention, there is provided an electrical connection body electrically connected to the anisotropic conductive film according to the first to sixth aspects, wherein the electrical connection body is connected to a film connection electrode on the flexible film. An electrode connection is made between the substrate electrode of the connection substrate and the substrate electrode.

According to an eighth aspect of the present invention, in the electrical connection body according to the seventh aspect, the substrate electrode is made of copper, tin-plated copper, gold, solder-plated copper, aluminum, silver, nickel, palladium, platinum. , ITO glass, and IO glass electrodes. According to a ninth aspect of the present invention, in the electrical connection body according to the seventh or eighth aspect, the connection substrate is a liquid crystal panel,
It is a printed circuit board or a hybrid IC board.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. The conductive particles of the present invention are characterized in that the outermost layer [m + n] is a tin or tin alloy layer, and examples of tin alloy layers include tin / silver, tin / copper, tin / bismuth, and tin / tin. Binary alloy layer of zinc, ternary alloy layer of tin / silver / copper, tin / silver / indium, tin / silver / bismuth, tin / zinc / bismuth, and quaternary tin / silver / copper / bismuth Alloy layer, tin / silver /
It is known that the effect is exhibited even with a pentagonal alloy layer of copper / bismuth / germanium.

The outermost layer is preferably a tin-only layer, tin /
It is a binary alloy layer of silver, tin / copper, tin / bismuth, and tin / zinc, and more preferably a tin-only layer, tin / silver, tin / copper,
It is a binary alloy layer of tin / bismuth. In other words, since the outermost layer is a tin or tin alloy layer, the contact resistance at the contact point is small, and it is soft. Even when pressed, the electrode does not deform irregularly, and the composite conductive particles deform. In addition, it has sufficiently excellent characteristics for a high-density pitch requiring dispersibility, such as a sufficient contact area can be ensured.

Tin or copper on and near the surface of the conductive particles;
The concentrations of bismuth, silver and the like were determined as surface concentrations at a depth of about 30 A from the surface using an X-ray photoelectron spectrometer ESCALB200-X manufactured by VG of the United Kingdom.
In this case, the tin concentration was Sn3d (Kα line of Mg), the copper concentration was Cu3p (Kα line of Mg), and bismuth was Bi4f.
(Kα line of Mg), silver concentration is Ag3d (Kα line of Al)
The energy count value was calculated by converting the energy count value to% by weight using the peak of (1).

On the other hand, the average concentration of each element in the conductive particles is determined by dissolving a sample in concentrated nitric acid and using a high frequency inductively coupled plasma emission spectrometer (JY manufactured by Seiko Denshi Kogyo KK).
38P-P2 type). The average particle diameter is 2.5 to 40 μm and the average particle diameter ± 2 μm is 80% by volume or more,
If the average particle diameter exceeds 40 μm, the existing particles are too large, and when crushed, they have a contact with an adjacent electrode, which undesirably generates a leak current. Average particle size 1
If it is less than μm, the particles between the electrodes will be smaller than the thickness of the electrodes, resulting in insufficient contact, and furthermore, the aggregation between the particles will increase, making the dispersion extremely difficult. The preferred average particle size is 2.5 to 20 μm, more preferably 3 to 1 μm.
0 μm.

The ratio of particles having an average particle diameter of ± 2 μm is 8
When the content is 0% by volume or more but less than 80% by volume, a combination in which the particle size distribution is too wide and no particles are present between the electrodes may occur. Preferably, it is at least 85% by volume.
About the average particle diameter and the particle diameter distribution of the composite conductive particles of the present invention, a laser diffraction type particle size distribution analyzer (HEL
OS & RODOS: Japan Laser) or a scanning electron microscope (SEM: Hitachi S-2700). The measured value was a volume-based particle size distribution, and the average particle size was a value of 50% by volume on a volume integration basis.

In the present invention, the oxygen content of the conductive particles is the total oxygen content on the surface and inside of the particles, and is measured by an oxygen / nitrogen simultaneous analyzer (EMGA650 manufactured by Horiba, Ltd.) by an inert gas impulse heating and melting method. be able to. If the oxygen content exceeds 5000 ppm, there is a possibility that poor conductivity due to the oxide film may occur. The preferred oxygen content is 3000 ppm or less, more preferably 2000 ppm or less.

The metal constituting the conductive particles is a metal particle which does not contain lead, which is said to emit α rays which may cause malfunction of the semiconductor element, toxicity to the human body, and reduction as an environmental problem. Features. At normal temperature,
It is characterized by containing any three or more of the elements that are in a metallic state at normal pressure, but is preferably gold, silver, copper,
Tin, bismuth, zinc, nickel, palladium, chromium,
Indium, antimony, aluminum, germanium, silicon, and beryllium are more preferable, and gold, silver, copper, tin, bismuth, zinc, indium, and germanium are more preferable.

The metal particles serving as the central nucleus [m] of the conductive particles developed by the present inventors are to prevent the composite conductive particles from being shattered by the influence of heat, load or the like during connection, thereby causing problems. Was invented. The Ag concentration on the surface and in the vicinity of the surface of the core metal particles [m] was determined as a surface Ag concentration at a depth of about 30 ° from the surface using an X-ray photoelectron spectrometer ESCALAB200-X manufactured by VG of the United Kingdom. Things. The Ag concentration at this time was Ag3d
It is obtained by comparing peaks of _5/2 (Kα line of Al) and Cu3p (Kα line of Mg). On the other hand, the average Ag concentration is obtained by dissolving a sample in concentrated nitric acid and using a high-frequency inductively coupled plasma emission spectrometer (manufactured by Seiko Denshi Kogyo KK)
Y38P-P2).

Further, since the core core metal particles have a region in which the Ag concentration on the surface thereof is higher than the average Ag concentration of the particles, the oxidation resistance of the core metal particles is improved, and the nickel base treatment (commonly used) is performed. (Formation of a diffusion prevention layer referred to as described above) is not required, and an alloy layer can be formed by an Ag-Cu alloy layer of central core metal particles and an outer layer thereof. At this time, if the Ag content x of the metal particles is less than 0.001, sufficient oxidation resistance cannot be obtained, and if it exceeds 0.4, the production cost of the metal particles increases. The preferable range of the amount x of Ag is 0.005 ≦ x ≦ 0.3, and more preferably 0.02 ≦ x0.25.

The average particle diameter is 2.5-35 μm and the average particle diameter ± 2 μm is present in a proportion of 80% by volume or more.
In the case of exceeding, the existing particles are too large, and when crushed, it has an adjacent electrode and a contact point, and it is not preferable because a leak current is generated. Therefore, the average particle diameter of the metal particles serving as the central core is 35 μm or less. Is preferred. Average particle size 2.5 μm
If it is less than 1, the particles between the electrodes are smaller than the thickness of the electrodes, resulting in insufficient contact, and furthermore, the aggregation between the particles becomes large and the dispersion becomes extremely difficult.

Further, the cohesive force between the metal particles is increased, and it is difficult to form a composite. Preferred average particle size is 2.5 to 20
μm, and more preferably 3 to 10 μm. Also,
The ratio of particles having an average particle diameter of ± 2 μm is 80% by volume or more, but if it is less than 80% by volume, a combination in which the particle size distribution is too wide and no particles exist between the electrodes may occur. Preferably, it is at least 85% by volume. The average particle size and the particle size distribution of the conductive particles of the present invention were measured using a laser diffraction type particle size distribution analyzer (HELOS & RODOS: Nippon Laser) or a scanning electron microscope (SEM: Hitachi Ltd. S-2700). . The measured value is based on the volume-based particle size distribution, and the average particle size is 50 based on the volume integration.
Volume% values were used.

In the present invention, the oxygen content of the core metal particles is the total oxygen content on the surface and inside of the particles, and is measured by an oxygen / nitrogen simultaneous analyzer (EMGA650, manufactured by Horiba, Ltd.) using an inert gas impulse heating and melting method. can do. If the oxygen content exceeds 5000 ppm, there is a possibility that poor conductivity due to the oxide film may occur. The preferred oxygen content is 3000 ppm or less, more preferably 2000 ppm or less.

Also, since the surface of the central core particle has a very fine uneven shape (the difference in height between the convex portion and the concave portion is 1 μm or less), it is suitable for increasing the strength in bonding with the outer layer. They also found that the structure was like an anchor effect, and the structure did not cause separation between the central core of the metal particles and the outer layer. The method for producing metal particles serving as the central core of the conductive particles of the present invention is obtained by atomizing a metal melt having such a composition with a high-pressure inert gas.In particular, nitrogen gas and helium gas are used. Is good. The particle shape is preferably spherical. However, if the particle shape is far off from the spherical shape, a combination of the particles existing between the substrate electrode and the chip electrode without having both contact points is likely to occur.

The conductive particles of the present invention not only have good low-temperature connectivity, oxidation resistance, and silver migration resistance, but also have good dispersibility, good bonding to electrodes (easy to deform), high current density, and high conductivity. This has never before been able to ensure sufficient electrical continuity with fine pitch electrodes, which has high performance and can respond to colorization and high density of liquid crystal panels and the like. The present invention provides an anisotropic conductive film containing 0.05 to 300 parts by weight of an organic binder with respect to 1 part by weight of conductive particles having such a composition, and can be used in the present invention. As the organic binder, one or more types selected from a thermosetting resin, a photocurable resin, an electron beam curable resin, a thermoplastic resin, and a photothermosetting resin can be used.

Examples of the thermosetting resin include an epoxy resin, a resol type phenol resin, a polyamide resin, a silicone resin, a novolak type phenol resin, a polyurethane resin, a polyimide resin, and a thermosetting acrylic resin. As epoxy resin, bisphenol A type,
Alicyclic epoxy, chain epoxy, epoxy acrylate, epoxy novolak type, bisphenol F type, brominated bisphenol A type, fatty acid modified epoxy, polyalkylene ether type, diglycidyl ester type, heterocyclic epoxy, etc. Can be Also, if necessary,
Known reactive diluents can also be used. For example, a mixture of diglycidyl ether, ethylene glycol diglycidyl ether, 1,3-butanediol diglycidyl ether, diethylene glycol diglycidyl ether, or the like can be used.

If necessary, known curing agents can be used, for example, aliphatic diamines (epoxy and aliphatic polyamine addition polymers), polyamines and aromatic diamines (metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfate) Fon), acid anhydrides (methylnadic anhydride, hexahydroacid anhydride, pyromellitic anhydride, Lewis acid complex compound), Korea, phenol, melamine, phenol compounds, and mercaptan compounds. Examples of the reactivity accelerator include tertiary amines, amine salts, and imidazole-based curing agents (2-ethyl-4 (5) -methylimidazole, 1-cyanoethyl-2-4 (5) -methylimidazole, 2-heptadecylimidazole). , 2-methylimidazole azine, 2-undecylimidazole, liquid highly active imidazole). Carboxylic acid compounds are preferred as the amine-based curing agent.
There are also dicyandiamide and benzoguanamine.

As the silicone resin,-(R ₂ Si
O) A resin represented by the structural formula of n-. (In the formula, R represents a methyl or phenyl group.) As the phenol resin, a resol type phenol resin and a novolak type phenol resin can be used, and as the resol type phenol resin, phenol formaldehyde type resole resin, alkylphenol resole type, xylene resin modified resole type, rosin modified phenol resin, etc. No.

Examples of the polyimide resin include a condensation type polyimide, a bismaleide resin, and an addition type polyimide resin. As the polyurethane resin, it is preferable to use a urethane prepolymer that forms urethane. Preferably, those mainly using a block isocyanurate in which a terminal active isocyanate group is blocked with an active hydrogen compound are mainly used. As the thermoplastic resin, thermoplastic acrylic resin, butyral resin, vinyl chloride resin, urethane resin, polyethylene terephthalate resin, polyethylene resin, polypropylene resin, polystyrene resin, ABS resin, polycarbonate resin, polyamide resin, unsaturated polyester resin, diallyl phthalate Resin, fluorine resin, polyphenylene sulfide resin, polyether imide resin, polyether ketone resin, polyether ether ether ketone resin, polyether sulfone resin, polyarylate resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyamide imide resin , Modified polyphenylene oxide resin, AAS resin, AES resin, ACS resin, AS resin and the like.

As the photo-curable resin, a photo-polymerizable oligomer and a photo-polymerizable monomer are used, and if necessary, a photo-initiator and a photo-initiating assistant are used to cure the resin. The photopolymerizable oligomer is a low-molecular-weight reactive molecule (several hundreds to thousands), which is obtained by adding two or more acrylic groups and methacryl groups as functional groups to a skeleton of polyester, epoxy, urethane, or the like. , Epoxy acrylate, urethane acrylate, polyester acrylate, and polyether acrylate.

As the photopolymerizable monomer, an acryloyl group (CH ₂ ＣＨCHCO—) or a methacryloyl group (CH ₂
= C (CH ₃ ) CO-) per molecule having one or more than one, and a monofunctional (meth) acrylate having one, a polyfunctional (meth) acrylate having two or more, and a vinyl group (CH Those having ₂ = CH-) are preferred.
Examples of the monofunctional acrylate include allyl acrylate, allyl methacrylate, benzyl acrylate (meth), isobornyl acrylate, cyclohexyl acrylate (meth), N, N-dimethylaminoethyl acrylate, glycidyl methacrylate, lauryl acrylate, and polyethylene acrylate 90. Examples include methacrylate and trifluoroethyl methacrylate.

As the polyfunctional acrylate, for example,
1,4 butanediol diol diacrylate, 1,6
Hexanediol diacrylate, diethylene glycol diacrylate, neopentyl glycol acrylate, polyethylene glycol 400 diacrylate, tripropylene glycol diacrylate, bisphenol A diethoxy diacrylate, tetraethylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, etc. Is mentioned. As the reactive monomer having a vinyl group, for example, styrene, vinyl toluene, vinyl acetate,
N-vinylpyrrolidone and the like can be mentioned.

A photoinitiator is used together with the above photopolymerizable oligomers and photopolymerizable monomers, and a substance which easily absorbs ultraviolet rays and easily generates radicals is preferable. Known acetophenone type, thioxanthone type, benzoin type and peroxide type are known. Substances can be used. For example, diethoxyacetophenone, 4-phenoxydichloroacetophenone, benzoin, benzoin ethyl ether, benzoin isopropyl ether, benzyldimethyl ketal, benzophenone, 4-phenylbenzophenone, acrylated benzophenone, thioxanthone, 2-ethylanthraquinone, and the like. Further, as the photoinitiator, when used with the photoinitiator, the initiation reaction is promoted more than the photoinitiator alone, and the curing reaction is made more efficient,
Known photoinitiating aids such as aliphatic and aromatic amines can be used. For example, a known photoinitiating auxiliary such as triethanolamine can be used. For example, triethanolamine, N-methyldiethanolamine, Michler's ketone,
4,4-diethylaminophenone and the like.

If necessary, antioxidants (eg, higher aliphatic, linolenic acid, balmitic acid, oleic acid, stearic acid, linoleic acid and copper salts thereof, triazole compounds such as benzotriazole, tolyltriazole, etc.) Polymerized phosphates, alkanolamines), thixotropic agent dispersants (silane coupling, aluminum coupling, zirconium coupling agents) and the like can also be added. In addition, a known plasticizer can be used. In this case, 0.0001 to 1 with respect to 100 parts by weight of the conductive powder.
There is an effect when used by adding 5 parts by weight.

In the case of an anisotropic conductive film, the conductive particles are preferably prepared in a highly dispersed state in the organic binder. The anisotropic conductive film may be in a completely dried or cured state. Rather, those in a semi-cured state are more preferable. The anisotropic conductive film does not need to have conductivity by itself, but is preferably an insulative one. In other words, it is sufficient that the film is sandwiched between the flexible insulating film and the substrate and is pressed and heated to exhibit conductivity only in the direction of the electrode and the counter electrode, and the film itself does not need to have conductivity. When it has conductivity, a short circuit occurs between adjacent electrodes.

Although the form of the anisotropic conductive film depends on the size and number of the connection electrodes, a width of 0.1 to 2000 mm is generally used, but is not particularly specified. Preferably, 0.2-200 mm, more preferably 0.3
５０50 mm. The thickness of the anisotropic conductive film is required, and a thickness of about 3 to 200 μm is preferable. The length of the anisotropic conductive film is not particularly specified. For example, it is preferable to cut and use a film having a length of several tens of meters as needed.

The present invention provides an anisotropic conductive film in which the connection electrode on the flexible insulating film and the substrate electrode to be connected are electrically connected only in the direction of the connection electrode and the counter substrate electrode. A known flexible insulating film can be used. For example, polyimide, polyethylene terephthalate, polybutylene terephthalate, polyarylate, polyamide imide, polyamide, polyethylene, alumina, polypropylene, polyphenylene sulfide, polysulfone, polyphenylene ether, polyether ketone, polyether ether ketone, polyarylate, tetrafluoroethylene, It is preferable to use one composed of at least one selected from epoxy and aluminum nitride.

As for the shape of the flexible insulating film, the width is particularly adapted according to the application, but the thickness is 5 to 5 mm.
000 μm is preferable, 5 to 500 μm is more preferable, and 5 to 200 μm is particularly preferable. In addition, the connection electrode on the flexible insulating film is used for external connection of a well-known circuit such as a conductor circuit, an IC circuit, or an LSI chip mounted or directly mounted on the flexible insulating film or via an adhesive. It means a conductor portion or a conductor portion electrically connected to a connected substrate. Capacitors, resistors, LSI, I
A chip component such as C or MCM may be mounted.

The connection electrodes on the flexible insulating film are made of copper, aluminum, gold, silver, platinum, palladium, silver-palladium, tin-lead, tin-lead-bismuth, gold-platinum, nickel, gold-plated nickel, copper- It is characterized by being at least one selected from silver alloy, silver-platinum, tin-lead solder-plated copper, and tin-lead solder-plated aluminum. The shape of the connection electrode depends on the size of the opposing substrate electrode, but is 6 to 5000 μm, preferably 10 to 1000 μm.
It may have a width or diameter of about μm. The thickness of the connection electrode is not particularly specified, but is preferably about 0.5 to 200 μm.

The connection conductor electrode (substrate electrode) on the substrate to which the connection electrode on the flexible insulating film is electrically connected via the anisotropic conductive film is made of ITO (indium-tin-oxide), tin oxide, oxide Indium, fluorine-doped tin oxide, tin-plated aluminum, tin-lead solder-plated aluminum, characterized by comprising at least one selected from palladium, the shape of the substrate electrode,
Good state of oxide thin film, metal or alloy foil. As a substrate electrode for a liquid crystal panel, ITO (indium-tin-oxide), tin oxide, indium oxide, and the like are preferable, and for example, those manufactured by a known method such as sputtering or vapor deposition may be used.

The substrate electrode in the case of a printed circuit board may be a substrate electrode manufactured by a known method for forming a circuit on the substrate by etching a conductor, printing a conductive paste, or the like. The thickness of the substrate electrode is preferably about 0.02 to 1000 μm, more preferably 0.09 to 200 μm,
0.1-100 μm is most preferred. Although the shape is not particularly specified, an electrode having a width of about 6 to 1000 μm is preferable. The distance between the electrodes (pitch) is preferably 6 μm or more, and more preferably 10 μm or more.

The substrate on which the substrate electrodes are formed may be a known substrate, but may be glass, paper phenol resin, glass epoxy resin, polyimide resin, alumina, aluminum nitride, cordierite, mullite, amorphous silicon, Single crystal silicon, polycrystalline silicon, aluminum, nickel, cadmium compound, enamel, polyamide resin, polyphenylene ether resin, polyphenylene sulfide resin, polyether ketone resin, tetrafluoroethylene resin, polyether sulfone resin, polyarylate resin, polyethylene terephthalate resin One or more hard or flexible substrates selected from polyetheretherketone resins are preferred.

In the case of a liquid crystal panel, a glass substrate is preferable. As the glass, known glass materials can be used, but alkali zinc borosilicate, sodium borosilicate,
Glasses selected from soda lime, low alkali borosilicate, barium borosilicate, borosilicate, aluminoborosilicate, aluminosilicate, 96% silicic acid, fused silica glass, synthetic silica glass, and the like are preferable. In the case of a printed circuit board, paper phenol resin, glass epoxy resin, polyimide resin and the like are preferable.

The substrate preferably has a thickness of 0.01 to 40 mm. The substrate may be a multilayer, and may be a substrate having 2 to 20 layers. When the paste of the composition for anisotropic conductive connection of the present invention is applied and used, as described above,
Using a technique of screen printing or a dispenser, print application (including portions other than the electrode portion) is performed on the substrate electrode in advance.
At this time, the printing or coating thickness is preferably about 7 to 50 μm. When a solvent or a volatile component is contained, after sufficiently drying, the connection electrodes on the flexible insulating film are aligned, and the temperature is adjusted to about 0.1 to 12 at a temperature of about 50 to 250 ° C.
The connection is made by applying a pressure of about MPa.

As a method for connecting the connection electrode on the flexible insulating film to the connected substrate electrode using the anisotropic conductive film of the present invention, a known method may be used. For example, as described above, the anisotropic conductive film is laminated on the connection electrode of the substrate. 50-120 ° C as required
Temporarily press at a temperature as low as about 0.1 to 7 MPa. Thereafter, if necessary, the guide film (for example, tetrafluoroethylene) of the anisotropic conductive connection film is peeled off. Further, the connecting electrodes of the flexible insulating film are aligned, the connecting electrodes of the flexible insulating film are further aligned, and further, using a heat tool, at a temperature of about 60 to 250 ° C. and 0.2 to 15 MPa.
Pressure and pressure are applied at about a. Pressure is 0.2-10MPa
Degree is preferable, and 0.6 to 5 MPa is more preferable.

In the anisotropic conductor thus obtained, at least particles having both contacts exist among particles existing between the connection electrode on the flexible insulating film and the opposing substrate electrode. In such a case, the conductive particles having such a composition of the anisotropic conductor may be slightly deformed when pressurized. For example, the deformation of the spherical particles may increase the contact area at the contact. When it is deformed, it can be crushed to 0.3 μm at the shortest distance between the connection electrodes, depending on the distance between the connection electrodes and the counter substrate electrode. At this time, it is necessary to prevent the crushed particles from spreading laterally so as to have a contact with an adjacent electrode, and it is preferable that the crushed particles be controlled by the pitch between adjacent electrodes or terminals.

The distance between the connection electrode and the counter substrate electrode is 0.3
μm or more and 30 μm or less, more preferably 1 μm
m to 30 μm, particularly preferably 1 μm to 25 μm
It is as follows. For example, in the case of spherical particles, the deformation ratio of the particles is the ratio of the length between the connection electrode on the flexible insulating film and the counter substrate electrode and the length of the longest part of the particles in the direction parallel to the flexible insulating film or the substrate). (The direction parallel to the insulating film or the substrate / between the electrodes) is preferably 0.1 to 30, but is not particularly specified.

The connection resistance between the electrodes of the anisotropic conductor thus obtained is a value of 100 Ω or less, and the lower the resistance, the better. The present invention further provides a liquid crystal display using the anisotropic conductor, a printed circuit board, a plasma display, a thermal head, and a membrane switch. Can be used for a simple matrix drive system and an active matrix drive system.

As a display method, a twist nematic method, a ferroelectric positive liquid crystal display method FLC or SSF
TFT combined with LC method, polymer dispersed liquid crystal method, phase transition method, dynamic scattering method, TN method
(META) using a diode as a switching element in the active matrix method
Naturally, a method of increasing the contrast by L-INSULATOR-METAL can also be used. Naturally, it is used for a display that can sufficiently handle monochrome and color. In addition, the electrode connection pitch of the liquid crystal display can be used when the electrode connection pitch is about 5 to 1000 μm.

The anisotropic conductive film of the present invention can be used for connecting a flexible insulating film to a printed circuit board. As described above, the flexible insulating film may, of course, be one in which a conductor circuit and a chip component (capacitor, resistor, LSI, etc.) are formed and mounted on the insulating film. The printed circuit board to be connected includes a hybrid IC, a board subjected to a copper foil etching treatment, a board formed of a conductive paste by a screen printing method, and a multilayer resin board (for example, 2 to 20 layers). is there. There is no particular designation, and a known printed board may be used. In this case, for example, as the conductor electrode on the substrate, a copper foil (for example, 5 to 50 μm thick) formed by etching is preferable.

By using the composition for anisotropically conductive connection of the present invention to connect a flexible insulating film (for example, a flexible printed circuit board) to an electrode on a printed circuit board, fine printed wiring ( Sufficient conduction can be ensured even when the width is, for example, 30 to 400 μm. Also in this case, the conductive particles softly fit any connection electrodes on the printed circuit board,
It has the feature that the electrode on the substrate is not easily damaged. The connection method may be the connection method described above. Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the scope of the Examples.

[0056]

Example 1 16 kg of Cu particles (purity 99% by weight or more)
And 4 kg of Ag particles (purity 99% by weight or more) are put into a graphite crucible and melted at 1400 ° C. by a high frequency induction heating device.
Heated. The atmosphere was performed in nitrogen of 99% by volume or more.
Next, after introducing the molten metal from the tip of the crucible into a spray tank in a helium gas atmosphere, a helium gas (purity of 99% by volume) was supplied from a gas nozzle provided near the tip of the crucible.
As described above, an atomization (manufactured by Makabe Giken) was performed by ejecting an oxygen concentration of 0.1% by volume and a pressure of 3.2 MPaG) to produce metal particles. Observation of the obtained metal particles with a scanning electron microscope (S-2700 manufactured by Hitachi, Ltd.) revealed that the particles were spherical (volume average particle diameter: 12 μm). Ag on the surface of this metal particle
The concentration was measured by X-ray photoelectron spectroscopy (X-ray photoelectron spectrometer ESCALAB200-X manufactured by VG, UK), and the average Ag concentration of the metal particles was dissolved in concentrated nitric acid and plasma emission spectroscopy (Seiko Denshi Kogyo ( JY38P-
P2 type). The average ratio of Ag concentration to the surface of the obtained metal particles was 2.2.

Further, embedding in an epoxy resin, metal particles
The cross section was observed with an electron microscope.
There was no void, and the difference between the heights of the convex and concave portions was 0.5 μm.
Was. The obtained conductive particles are subjected to an airflow classifier (Nisshin Engineer).
Alling). The obtained classified powder has an average particle size.
6.5 μm and an oxygen content of 800 ppm.
Was. In addition, the abundance ratio of classified powder contained in 6.5 ± 2 μm
Was over 99%. The guide obtained by the method described above
Rotating plating equipment (flow from Uemura Kogyo Co., Ltd.)
In the sloop looper RP-1), the plating pretreatment is water
Sn plating was performed only by washing. Sn plating solution is Sn / P
Removed Pb component from solution composition for b-eutectic solder plating
Composition, plating temperature 25 degrees, current density 0.15
A / dm ²The plating time was 0.5 hours.

As a result of observing 100 of the obtained conductive particles with a scanning electron microscope, the volume average particle size was 8.5 μm. The plating thickness by cross section observation was 1 μm.
Furthermore, elemental analysis of the particle surface and center (Horiba Seisakusho E
MAX-5770), the following results were obtained. The line type used in the analysis was Ag; Lα
Line, Cu; Kα line, Sn; Lα line, and the energy count value was converted to% by weight. Next, an elemental analysis of the outermost surface (about 30 ° depth from the surface) was performed by X-ray photoelectron spectroscopy. The peaks used in the analysis were Ag3d _3/2 (Kα line of Mg) and Cu3p
(Kα line of Mg) and Sn3d _5/2 (Kα line of Mg). As a result, it was confirmed that only Sn was present on the outermost surface.

Finally, the conductive particles are converted to DS by Shimadzu Corporation.
The endothermic peak temperature (indicating the melting point) was measured under a nitrogen atmosphere by C-50. As a result, 217 degrees, 353 degrees, 4
Endothermic peaks were present at 90 and 610 degrees. Since the upper limit of the operating temperature of the measuring device was 720 ° C. and the melting point of the alloy particles used as the core was unknown, only the core metal particles were separately measured under a nitrogen atmosphere using a high-temperature microscope manufactured by Vacuum Riko. However, it was observed that the metal particles could not maintain a spherical shape at around 780 degrees, and could be completely dissolved at 990 degrees.
It was confirmed that the endothermic peak obtained by the SC measurement was derived from the plating layer.

[0060]

Example 2 Inert gas atomization and classification were performed in the same manner as in Example 1, and Sn / Bi plating was performed using a rotating plating apparatus with the metal particles as nuclei, and the plating pretreatment was performed only with water washing. The Sn / Bi plating solution had a composition obtained by adding 5% by weight of Bi to the Sn plating solution, and was performed at a plating temperature of 25 ° C., a current density of 0.15 A / dm ² , and a plating time of 0.5 hour. The obtained conductive particles were subjected to 100 scanning electron microscopy.
As a result of observation, the volume average particle size was 8.5 μm.
In addition, the conductive particles were embedded in an epoxy resin, and after polishing, the cross section was observed with a scanning electron microscope. The plating thickness by cross section observation was 1 μm. Further, when the elemental analysis of the particle surface and the center was performed, the following results were obtained. The line types used in the analysis were Ag; Lα line, C
u; Kα line, Sn; Lα line, Bi; Mα line, and the energy count value was converted to% by weight.

Next, elemental analysis of the outermost surface (depth 3 from the surface)
(About 0 °) was carried out by X-ray photoelectron spectroscopy. The peaks used in the analysis were Ag3d _3/2 (Kα line of Mg), Cu3p (Kα line of Mg), and Sn3d _5/2 (Kα line of Mg).
Line) and Bi4f (Kα line of Mg). As a result, it was confirmed that Sn and Bi existed on the outermost surface. The abundance ratio was 46% by weight of Sn and 54% by weight of Bi. Further, the endothermic peak temperature (indicating the melting point) of the conductive particles was measured by DSC under a nitrogen atmosphere. As a result, 1
Endothermic peaks were present at 38 degrees, 217 degrees, 353 degrees, 490 degrees, and 610 degrees. When the melting point of the metal particles used as the nucleus was separately measured under a nitrogen atmosphere with a high-temperature microscope, it was observed that the metal particles could not maintain a spherical shape around 780 ° C. and were completely dissolved at 990 ° C. It was confirmed that the endothermic peak obtained by the DSC measurement was derived from the plating layer.

Using the conductive particles obtained in the above Examples 1 and 2, an anisotropic conductive film was prepared while attaching a guide tape with a coater in a thickness of 5 to 5000 μm. Regarding the width, it was prepared in the range of 0.1 to 2000 mm. Furthermore, using the produced anisotropic conductive film, at least 100 (or 10
(0) or more electrodes were aligned with each other, and temporarily press-bonded on the substrate (a flexible insulating film may be used).
The temperature was in the range of 50 to 120 ° C./1 to 10 seconds.
The pressure was increased using a heat tool in the range of 0.05 to 5 MPa. Thereafter, the guide tape (which may be omitted) is peeled off, and the connection electrode of the flexible insulating film (which may be a substrate) is aligned with the counter substrate electrode, and the pressure is set at a temperature of 60 to 200 ° C./1 to 60 seconds. 0.1
Full connection was made at １２12 MPa. The electrode pitch (distance between conductors) was 40 to 200 μm.

Table 1 shows the composition of the produced anisotropic conductive film, Table 2 shows the form of the obtained anisotropic conductor, and Table 3 shows the properties after the environmental test. The evaluation criterion is based on the resistance value (2) between the connection electrode on the flexible insulating film and the counter substrate electrode.
0Ω or less is good), and insulation between adjacent electrodes (85 ° C. 9
0% (after standing for 1000 hours), good or bad (100 or more pieces are 10 ⁸ Ω or more, good 、, 50 to 99 pieces (pieces), 49 or less are x), and resistance value after environmental test The rate of change was evaluated as good (the rate of change within 20% after 85 cycles of 85 ° C./30 minutes—55 ° C./30 minutes—1000 cycles is good). The application is also shown.

[0064]

Comparative Example A commercially available water atomized copper powder was classified with an airflow classifier and the average particle size was adjusted. The oxygen content after classification is 1
It was 800 ppm. Using the copper powder, an anisotropic conductive film was produced in the same manner as in the example with the exact same composition ratio as shown in Table 1 (Table 4) and evaluated similarly. The evaluation results are shown in Tables 5 and 6.

[0065]

[Table 1]

[0066]

[Table 2]

[0067]

[Table 3]

[0068]

[Table 4]

[0069]

[Table 5]

[0070]

[Table 6]

[0071]

The conductive particles of the present invention have good low-temperature connectivity, conductivity, oxidation resistance, and dispersibility, and are free from lead, so they are friendly to the human body and the environment. Furthermore, tin alloys, silver, copper, etc. The contact area can be increased by being appropriately deformed at the time of bonding between the electrode and the conductor. We provide anisotropic conductors with features such as high connection reliability, connectivity at fine pitch and high current density by using an anisotropic conductive film using conductive particles in consideration of this environmental problem. can do.

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 4F100 AB10B AB11B AB12B AB13B AB14B AB16B AB17B AB18B AB20B AB21B AB22B AB24B AB25B AB31B AK01A AR00B BA02 DE01B GB41 JA04B JB03 JG01B JK17A YY00B 5G307HA02 H03

Claims (9)

[Claims] 1. An anisotropic conductive film having a flexible film, an organic binder, and conductive particles, wherein the conductive particles have a central core [m] of a metal alloy having a high melting point; [M + 1] layer, [m + 2] layer,... [M + n]
The core and the melting point of each layer (m) m
p, (m + 1) mp, (m + 2) mp ... (m + n)
When expressed as mp, the melting point of the central core and each layer is (m) mp>
(M + 1) mp> (m + 2) mp...> (M + n) m
p, wherein the organic binder is contained in an amount of 0.05 to 300 parts by weight based on 1 part by weight of the conductive particles. 2. The anisotropic conductive film according to claim 1, wherein the metal constituting the conductive particles is at least three kinds, and the layers other than the outermost layer are alloy layers with the central core [m]. ,
An anisotropic conductive film, wherein the outermost [m + n] layer is a tin or tin alloy layer. 3. The anisotropic conductive film according to claim 1, wherein said conductive particles have an average particle size of 2.5 to 40.
An anisotropic conductive film characterized in that the content of particles having an average particle diameter of ± 2 μm in μm accounts for 80% by volume or more and the oxygen content is 5000 ppm or less. 4. The anisotropic conductive film according to claim 1, wherein said conductive particles are composed of gold, silver, copper,
Tin, bismuth, zinc, nickel, palladium, chromium,
An anisotropic conductive film comprising at least three of indium, antimony, aluminum, germanium, silicon, beryllium, tungsten, molybdenum, manganese, tantalum, titanium, neodymium, and magnesium. 5. The anisotropic conductive film according to claim 1, wherein the metal particles of the central nucleus [m] of the conductive particles are of the general formula AgxCuy [0.001 ≦ x ≦ 0.4, 0.6
≦ y ≦ 0.999, x + y = 1 (atomic ratio)],
The average particle diameter is 2.5 to 35 μm, the content of the average particle diameter ± 2 μm particles accounts for 80% by volume or more, and the oxygen content is 50%.
The central core particle surface has a fine unevenness (the difference between the height of the convex portion and the concave portion is 1 μm or less) in which the Ag concentration of the central core particle surface is higher than the average Ag concentration of the particles. An anisotropic conductive film, characterized in that: 6. The anisotropic conductive film according to claim 1, wherein said organic binder is selected from a thermosetting resin, a thermoplastic resin, a photocurable resin, an electron beam curable resin, and a photothermosetting resin. An anisotropic conductive film comprising one or more resins. 7. An electrical connection body electrically connected to the anisotropic conductive film according to claim 1, wherein a film connection electrode on the flexible film, a substrate electrode of the connection substrate connected to the flexible film, An electrical connection characterized in that electrodes are connected between the two. 8. The electrical connector according to claim 7, wherein said substrate electrode is selected from copper, tin-plated copper, gold, solder-plated copper, aluminum, silver, nickel, palladium, platinum, ITO glass, and IO glass electrodes. An electrical connector, characterized in that it is at least one kind. 9. The electrical connector according to claim 7, wherein said connection board is any one of a liquid crystal panel, a printed board, and a hybrid IC board.