JPH11134935A - Conductive fine particles, anisotropic conductive adhesive and conductive connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide conductive fine particles, anisotropic conductive adhesive, and conductive connection structure which have a low connection resistance, a large current capacity at the time of connection, are stable in connection, and do not cause a leak phenomenon. I do. SOLUTION: The conductive fine particles having a metal sphere as a nucleus, wherein the metal sphere has an average particle diameter of 0.3 to 25 μm, an aspect ratio of less than 1.5, and a CV value of 40% or less. .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to conductive fine particles, anisotropic conductive adhesive and conductive connection structure used for connection between fine electrodes.

[0002]

2. Description of the Related Art Anisotropic conductive materials include liquid crystal displays,
2. Description of the Related Art In electronic products such as personal computers and portable communication devices, small electronic components such as semiconductor elements are used to electrically connect substrates and to electrically connect substrates.

As such an anisotropic conductive material, a material obtained by mixing conductive fine particles with a binder resin is used. As the conductive fine particles, those obtained by applying metal plating to the surface of organic base particles or inorganic base particles have been used. As the conductive fine particles, for example, Japanese Patent Publication No. 6-96871, Japanese Patent Application Laid-Open No. 4-36902,
JP-A-4-269720, JP-A-3-25771
No. 0 is disclosed.

As an anisotropic conductive adhesive material obtained by mixing such conductive fine particles with a binder resin to form a film or paste, for example, JP-A-63-231
889, JP-A-4-259766, JP-A-3-291807, and JP-A-5-75250.

The conventional anisotropic conductive material has a problem that the current capacity at the time of connection is small since an electrically insulating material is used as a base material of the conductive fine particles.

In particular, in recent years, as electronic devices and electronic components have been reduced in size, wirings on substrates and the like have become finer, and the electrical resistance of connection portions tends to increase. Furthermore, recently developed devices for plasma display applications and the like may be of a large current drive type, and are required to handle large currents. In order to solve the problem of the current capacity, there is a method of increasing the concentration of the conductive fine particles in the anisotropic conductive material. However, when the concentration is increased, there is a problem that a leak easily occurs between adjacent electrodes. Was.

[0007] Further, the conventional anisotropic conductive material has a problem that the connection resistance between the electrode to be connected to a semiconductor, a small component, a substrate or the like and the conductive fine particles is high. this is,
Aluminum, nickel, copper, etc. are usually used as the material used for the electrodes, but their surfaces are oxidized, and when the conductive fine particles come into contact with these electrodes, they hit the surface oxide layer. It is considered that the cause was that it did not have hardness enough to break. Further, since the contact area between the electrode and the conductive fine particles is small, there is a problem that the contact resistance value is not reduced.

[0008] A technique using metal powder as the conductive fine particles is also disclosed in Japanese Patent Application Laid-Open No. 8-273440. However, although the metal powder can have a large electric capacity, it is difficult to obtain a true spherical one when the average particle size is 25 μm or less, and even a true spherical one often has a relatively large aspect ratio. In addition, since the particle diameters are not uniform and the CV value is large, a large amount of metal powder not involved in conduction is generated, and there is a disadvantage that leakage between the electrodes is likely to occur.

[0009]

SUMMARY OF THE INVENTION In view of the above, the present invention provides a conductive fine particle which has a low connection resistance, a large current capacity at the time of connection, a stable connection and does not cause a leak phenomenon.
It is an object to provide an anisotropic conductive adhesive and a conductive connection structure.

[0010]

The present invention provides conductive fine particles having metal spheres as nuclei, wherein the metal spheres have an average particle size of 0.3 to 25 μm, an aspect ratio of less than 1.5, and a CV value. 4
The conductive fine particles are 0% or less. Hereinafter, the present invention will be described in detail.

The conductive fine particles of the present invention have metal spheres as nuclei. The metal sphere has an average particle size of 0.3 to 25 μm.
m. If it is less than 0.3 μm, the conductive fine particles do not contact the surface of the electrode to be joined, and a gap may be formed between the electrodes, which may cause poor contact. If it exceeds 25 μm, the specific gravity of the metal sphere is large. For this reason, if a special treatment is not performed when the adhesive is used as an adhesive, a problem of settling in the matrix occurs. Preferably, it is 1 to 10 μm.

The metal sphere has an aspect ratio of less than 1.5. When it is 1.5 or more, since the particle diameters become irregular, when the electrodes are brought into contact with each other via the conductive fine particles, a large amount of particles that do not come into contact with each other and a leak phenomenon between the electrodes easily occur. Limited to range. It is preferably less than 1.2, more preferably less than 1.15, and even more preferably less than 1.1. Normal,
When the metal particles have a thickness of 25 μm or less, it is difficult to obtain true spherical particles because the particles are coalesced, and many have relatively large aspect ratios. In addition, the particle size is not uniform, and CV
The value should be large. Conventionally, it was difficult to obtain highly accurate metal particles by classification, but it was found that the cause was attraction between the metal particles. That is, the aspect ratio was controlled by lowering the metal concentration in the dispersion medium. However, the invention is not limited to the method described above. The aspect ratio is a value obtained by dividing the average major axis of the particle by the average minor axis.

The metal sphere has a CV value of 40% or less. If it exceeds 40%, the particle diameter becomes uneven,
When the electrodes are brought into contact with each other via the conductive fine particles, a large amount of particles that do not come into contact with each other easily cause a leak phenomenon between the electrodes. Preferably, 20
% Or less, more preferably 15% or less, and still more preferably 10% or less. In addition, the said CV value is a value represented by the following formula CV = ((sigma) / Dn) * 100 ((sigma) represents the standard deviation of a particle diameter, and Dn represents a number average particle diameter.).

The average particle size, aspect ratio and C in the above range
A metal sphere having a V value can be obtained, for example, by observing 300 arbitrary metal spheres with an electron microscope.
Further, the metal spheres can also be obtained by dispersing the metal spheres in a dispersion medium and performing classification by a drop speed. Generally, when metal particles having a certain concentration or more are dispersed in a dispersion medium, a phenomenon occurs in which metal particles coalesce due to an attractive force such as an electrostatic attractive force or a magnetic force acting between the metal particles. It is difficult to perform highly accurate classification operation. Therefore, in order to perform a highly accurate classification operation, it is preferable to lower the concentration of the metal spheres in the dispersion medium.

The metal sphere has a projection.
Is preferred. By forming protrusions on the metal sphere
The metal oxide on the electrode surface to be joined
Because it is easy to cut into the minute, the connection resistance is reduced,
The conductive connectivity can be stabilized. The protrusion
Is a metal material having an arbitrary surface 0.2
5Dn ^Two, The difference in distance from the center of the metal sphere is 0.
30% or more of particles exceeding 04Dn
Is shown.

Preferably, the metal sphere is coated with a resin. By providing a resin layer, which is an insulating layer, on the surface of the metal sphere, a short circuit between the electrodes due to contact between the conductive fine particles is prevented. In particular, when the conductive fine particles are used as an adhesive dispersed in an insulating resin matrix, the layer of the adhesive sandwiched between the electrodes flows when the electrodes are connected. Since the flow of the conductive fine particles differs from that of the conductive fine particles, the conductive fine particles may be concentrated in the insulating resin matrix, which is very effective in this case.

Further, the resin layer, which is an insulating layer, is softened or melted by heating at a contact portion with the electrode and is pushed away, so that the metal sphere directly contacts the electrode and is softened or melted. Since the resin fixes between the electrodes, the continuity of conductivity can be stabilized.

The resin is not particularly restricted but includes, for example, polyolefins such as polyethylene, ethylene-vinyl acetate copolymer and ethylene-acrylic acid copolymer; polymethyl (meth) acrylate, polyethyl (meth) acrylate, polybutyl ( (Meth) acrylate polymers and copolymers such as (meth) acrylate; polystyrene,
Styrene-acrylate copolymer, SB-type styrene-butadiene block copolymer, SBS-type styrene-
Butadiene block copolymers, block polymers such as hydrogenated compounds thereof; thermoplastic resins such as vinyl polymers and copolymers, crosslinked products thereof; thermosetting resins such as epoxy resins, phenol resins, and melamine resins; These mixtures and the like can be mentioned.

The resin layer formed of the above resin has a thickness of 20
Those which once soften at a temperature of 0 ° C. or lower are preferred. Also,
The thickness of the resin layer is 3 to 100% of the diameter of the metal sphere.
It is preferred that

The metal constituting the metal sphere is not particularly limited. For example, gold, platinum, palladium, silver, copper, nickel, cobalt, indium, tin, iron, lead, zinc, chromium, aluminum, and alloys thereof And the like. Among them, silver is preferable because it is excellent in price, oxidizing property, conductivity and the like. Further, copper is preferable because it is relatively inexpensive, does not cause migration, is hard, and can easily break through the insulating oxide film on the electrode surface, and has low connection resistance. Nickel is
It is preferable because it is relatively inexpensive, does not cause migration, is extremely hard, and can easily break through the insulating oxide film on the electrode surface, and has low connection resistance.

The method for producing the metal sphere is not particularly limited, and examples thereof include an atomizing method and a chemical reduction method. When the metal sphere is made of copper, a chemical reduction method is preferable from the viewpoint of oxidation.

The conductive fine particles of the present invention are not particularly limited as long as they have the above-mentioned metal sphere as a nucleus. For example, the above-mentioned metal sphere is coated with an organic compound, resin, inorganic substance or the like. There may be.

The conductive fine particles of the present invention are connected between these electrodes by being sandwiched between a plurality of electrodes, so that current can flow from one electrode to the other electrode via the conductive fine particles of the present invention. Although it is possible, since the conductive fine particles of the present invention use the metal sphere having excellent conductivity as a core material,
Large current capacity when connected. In addition, since the metal sphere is hard, it is possible to easily break through or sufficiently penetrate the insulating oxide film on the electrode surface, so that the connection resistance is small.

[0024] The present invention 2 is an anisotropic conductive adhesive comprising the conductive fine particles of the present invention 1 and an insulating resin. In this specification, the anisotropic conductive adhesive includes an anisotropic conductive film, an anisotropic conductive paste, and an anisotropic conductive ink.

The insulating resin used in the anisotropic conductive adhesive of the present invention 2 is not particularly restricted but includes, for example, thermoplastic resins such as acrylate resins, ethylene-vinyl acetate resins and styrene-butadiene block copolymers; A composition curable by heat or light, such as a curable composition of a monomer or oligomer having a glycidyl group and a curing agent such as isocyanate, and the like can be given.

The coating thickness of the anisotropic conductive adhesive of the present invention 2 is preferably from 10 to several hundreds μm. The connection object to which the anisotropic conductive adhesive of the present invention 2 can be used is not particularly limited as long as an electrode portion is formed on the surface thereof, and examples thereof include a substrate and a component.

The substrate is roughly divided into a flexible substrate and a rigid substrate. As the flexible substrate,
A resin sheet having a thickness of 50 to 500 μm is preferably used. The resin sheet is not particularly limited, for example,
Examples thereof include polyimide, polyamide, polyester, and polysulfone.

As the rigid substrate, a resin substrate and a ceramic substrate are preferably used. The rigid substrate made of the above resin is not particularly limited, and examples thereof include those made of glass fiber reinforced epoxy resin, phenol resin, cellulose fiber reinforced phenol resin, and the like. The rigid substrate made of ceramic is not particularly limited, and examples thereof include those made of silicon dioxide, alumina, and the like.

The substrate may be a substrate having a single layer structure. However, in order to increase the number of electrodes per unit area, a plurality of layers are formed by means such as formation of through holes and the like. It may be a multi-layer substrate that makes a physical connection.

The above components are not particularly limited, and include, for example, active components such as semiconductors such as transistors, diodes, ICs, and LSIs; and passive components such as resistors, capacitors, and crystal oscillators.

The shape of the electrodes formed on the surfaces of the substrate and the component is not particularly limited, and examples thereof include stripes, dots, and arbitrary shapes. The material of the electrode is not particularly limited, and examples thereof include gold, silver, copper, nickel, palladium, carbon, aluminum, and ITO. In order to reduce the connection resistance, copper, nickel or the like further coated with gold can be used. The thickness of the electrode is preferably 0.1 to 100 μm, and the width of the electrode is preferably 1 to 500 μm.

The anisotropic conductive adhesive of the present invention 2 and the above substrate,
As a joining method with the above-mentioned parts and the like, for example, the following methods are available. On a substrate or component with electrodes formed on the surface,
After mounting the anisotropic conductive film which is one embodiment of the anisotropic conductive adhesive of the second invention, a substrate or component having the other electrode surface is placed, and heated and pressed. Instead of using an anisotropic conductive film, a predetermined amount of conductive paste using conductive fine particles can be used by printing means such as screen printing or a dispenser. For the above-mentioned heating and pressurizing, a crimping machine equipped with a heater, a bonding machine or the like is used.

It is also possible to use a method that does not use the anisotropic conductive film or the anisotropic conductive paste. For example, after injecting a liquid binder into a gap between two electrode portions bonded together via conductive fine particles, A curing method or the like can be used.

The anisotropic conductive adhesive of the present invention 2 is the same as that of the present invention 1
When the electrodes are brought into contact with each other, almost no non-contacting conductive particles are generated, and a leak phenomenon between the electrodes hardly occurs. Further, there is no problem that the conductive fine particles settle in the insulating resin matrix.

The joined body of substrates or components obtained as described above is referred to as a conductive connection structure in this specification. That is, the present invention 3 is a conductive connection structure using the conductive fine particles of the present invention 1.

The conductive connection structure according to the third aspect of the present invention uses the conductive fine particles according to the first aspect of the present invention, and therefore can stably flow even with a considerably large current. Also,
Leakage between electrodes is less likely to occur.

[0037]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 A silver sphere having an average particle diameter of 8 μm, an aspect ratio of 1.2, and a CV value of 42% was dispersed in water at a concentration of 0.1%, and classification by a drop speed was repeatedly performed to obtain a conductive material of the present invention. Particles (average particle size 8 μm, aspect ratio 1.2, CV value 30%
Silver ball). The conductive fine particles were mixed and dispersed in a binder solution obtained by dissolving a mixture of an epoxy resin and an acrylic resin in toluene. Next, the conductive fine particle dispersion solution was applied on the release film to a constant thickness, and toluene was evaporated to prepare an anisotropic conductive film. The film thickness was 30 μm, and the concentration of the conductive fine particles was 15%.

Glass-epoxy copper-clad substrate (thickness 1.6)
mm, a wiring width of 50 μm, and an electrode pitch of 100 μm). 100μm thick on this
Polyimide film substrate (thickness 30 μm, wiring width 50
μm, electrode pitch 100 μm)
The mixture was heated and pressurized at 2 ° C. for 2 minutes to produce a conductive connection structure.

The connection resistance value of this conductive connection structure is 0.0
1Ω, low enough, connection resistance between adjacent electrodes is 1 × 10
^{With 9} or more, the line insulation was sufficiently maintained. Also, usually
When the concentration of the conductive fine particles in the anisotropic conductive film is increased, the electric resistance can be reduced. Therefore, when the concentration of the conductive fine particles was increased, no leakage occurred between the electrodes up to a concentration of 35%. .

Example 2 A test was conducted in the same manner as in Example 1 except that a silver sphere having an aspect ratio of 1.17 and a CV value of 18% was used. The connection resistance value of this conductive connection structure was sufficiently 0.006Ω. The connection resistance between adjacent electrodes was 1 × 10 ⁹ or more, and the line insulation was sufficiently maintained. In addition, when the concentration of the conductive fine particles in the anisotropic conductive film was increased, no leakage occurred between the electrodes until the concentration reached 40%.

Example 3 A test was conducted in the same manner as in Example 1 except that a silver sphere having an aspect ratio of 1.13 and a CV value of 13% was used. The connection resistance value of this conductive connection structure was sufficiently 0.004Ω. The connection resistance between adjacent electrodes was 1 × 10 ⁹ or more, and the line insulation was sufficiently maintained. When the concentration of the conductive fine particles in the anisotropic conductive film was increased, no leakage occurred between the electrodes until the concentration reached 50%.

Example 4 A test was conducted in the same manner as in Example 1 except that a silver sphere having an aspect ratio of 1.05 and a CV value of 8% was used. The connection resistance value of this conductive connection structure was sufficiently 0.002Ω. The connection resistance between adjacent electrodes was 1 × 10 ⁹ or more, and the line insulation was sufficiently maintained. When the concentration of the conductive fine particles in the anisotropic conductive film was increased, no leakage occurred between the electrodes until the concentration reached 60%.

Example 5 A test was conducted in the same manner as in Example 2 except that a silver sphere having an average particle diameter of 4 μm was used. As a result, the connection resistance value of this conductive connection structure was sufficiently low at 0.005Ω, and the distance between adjacent electrodes was small. Had a connection resistance of 1 × 10 ⁹ or more, and the line insulation was sufficiently maintained.
In addition, when the concentration of the conductive fine particles in the anisotropic conductive film was increased, no leakage occurred between the electrodes up to a concentration of 35%.

Example 6 0.4 μm silver particles were placed on silver spheres using a hybridizer.
Example 2 except that the projections were provided on the surface.
In a similar test, the connection resistance of this conductive connection structure was
Resistance value is sufficiently low at 0.004Ω, connection between adjacent electrodes
Resistance is 1 × 10 ⁹As described above, sufficient insulation between wires is maintained.
Was. Also, increase the concentration of conductive fine particles in the anisotropic conductive film.
The leak between the electrodes occurred until the concentration reached 40%.
Did not live.

Example 7 A test was conducted in the same manner as in Example 2 except that a silver sphere was coated with a 1 μm thermoplastic vinyl copolymer resin. The connection resistance value of this conductive connection structure was sufficiently low at 0.006Ω. The connection resistance between adjacent electrodes was 1 × 10 ⁹ or more, and the line insulation was sufficiently maintained. When the concentration of the conductive fine particles in the anisotropic conductive film was increased, no leakage occurred between the electrodes until the concentration reached 60%.

Example 8 The conductive fine particles of the present invention (silver spheres having an average particle diameter of 8 μm, an aspect ratio of 1.17 and a CV value of 20%) were mixed and dispersed in an epoxy resin to prepare an anisotropic conductive paste. This was applied to a glass-epoxy copper-clad substrate (thickness: 1.6 mm, wiring width: 50 μm, electrode pitch: 100 μm) to a substantially uniform thickness by a screen printing method. A thickness of 10
A polyimide film substrate of 0 μm (thickness 30 μm, wiring width 50 μm, electrode pitch 100 μm) is overlapped and
Heating and pressurization were performed at 50 ° C. for 2 minutes to produce a conductive connection structure.

The connection resistance value of this conductive connection structure is 0.0
06Ω, which is sufficiently low, and the connection resistance between adjacent electrodes is 1 × 1
With a value of ⁰⁹ or more, the line insulation was sufficiently maintained. In addition, when the concentration of the conductive fine particles in the anisotropic conductive paste was increased, no leakage occurred between the electrodes up to a concentration of 40%.

Comparative Example 1 A test was conducted in the same manner as in Example 1 except that a silver sphere having an aspect ratio of 1.2 and a CV value of 42% was used. The connection resistance value of this conductive connection structure was 0.03 Ω. Inferior to that of the invention, the connection resistance between adjacent electrodes is 1 × 10
^{Although the} line insulation was sufficiently maintained at ⁹ or more, when the concentration of the conductive fine particles in the anisotropic conductive film was increased,
Leakage between the electrodes occurred at a concentration of 30%.

Comparative Example 2 A test was conducted in the same manner as in Example 1 except that a silver sphere having an aspect ratio of 1.6 and a CV value of 30% was used. The connection resistance value of this conductive connection structure was 0.02 Ω. Inferior to that of the invention, the connection resistance between adjacent electrodes is 1 × 10
^{Although the} line insulation was sufficiently maintained at ⁹ or more, when the concentration of the conductive fine particles in the anisotropic conductive film was increased,
Leakage between the electrodes occurred at a concentration of 30%.

Comparative Example 3 A test was conducted in the same manner as in Example 5 except that a silver sphere having an aspect ratio of 1.2 and a CV value of 45% was used. The connection resistance value of this conductive connection structure was 0.02Ω. Inferior to that of the invention, the connection resistance between adjacent electrodes is 1 × 10
^{Although the} line insulation was sufficiently maintained at ⁹ or more, when the concentration of the conductive fine particles in the anisotropic conductive film was increased,
Leakage between the electrodes occurred at a concentration of 25%.

Comparative Example 4 A test was conducted in the same manner as in Example 1 except that a sphere plated with gold on a crosslinked polystyrene polymer having an aspect ratio of 1.05 and a CV value of 8% was used. Is sufficiently low as 0.02 Ω, the connection resistance between adjacent electrodes is 1 × 10 ⁹ or more, and the line insulation is sufficiently maintained, but the concentration of the conductive fine particles in the anisotropic conductive film is increased. As a result, leakage between the electrodes occurred at a concentration of 25%.

Comparative Example 5 Average particle size 200 μm, aspect ratio 1.05, CV value 8
When a test was conducted in the same manner as in Example 1 except that the silver spheres were used, particles were settled at the stage of the binder solution, and an anisotropic conductive film could not be produced successfully.

Comparative Example 6 A test was conducted in the same manner as in Example 1 except that silver powder having a particle size of 0.2 μm or less was used. Could not test. Examples 1 to 8, Comparative Examples 1 to
Table 1 shows the results of No. 6.

[0055]

[Table 1]

Example 9 Copper spheres obtained by a chemical reduction method and having an average particle size of 8 μm, an aspect ratio of 1.2 and a CV value of 42% were dispersed at a concentration of 0.1% in water. By repeating the process, conductive fine particles of the present invention (silver spheres having an average particle diameter of 8 μm, an aspect ratio of 1.2, and a CV value of 30%) were obtained. The conductive fine particles were mixed and dispersed in a binder solution obtained by dissolving a mixture of an epoxy resin and an acrylic resin in toluene. Next, the conductive fine particle dispersion solution was applied on the release film to a constant thickness, and toluene was evaporated to prepare an anisotropic conductive film. The thickness is 30 μm, and the conductive fine particles are 1 μm.
The concentration was 5%.

Glass-epoxy copper-clad substrate (thickness 1.6)
mm, a wiring width of 50 μm, and an electrode pitch of 100 μm). 100μm thick on this
Polyimide film substrate (thickness 30 μm, wiring width 50
μm, electrode pitch 100 μm)
The mixture was heated and pressurized at 2 ° C. for 2 minutes to produce a conductive connection structure.

The connection resistance value of this conductive connection structure is 0.0
1Ω, low enough, connection resistance between adjacent electrodes is 1 × 10
^{With 9} or more, the line insulation was sufficiently maintained. Also, usually
When the concentration of the conductive fine particles in the anisotropic conductive film is increased, the electric resistance can be reduced. Therefore, when the concentration of the conductive fine particles was increased, no leakage occurred between the electrodes up to a concentration of 35%. .

Example 10 A test was performed in the same manner as in Example 9 except that a copper ball having an aspect ratio of 1.17 and a CV value of 18% was used. The connection resistance value of this conductive connection structure was sufficiently 0.006Ω. The connection resistance between adjacent electrodes was 1 × 10 ⁹ or more, and the line insulation was sufficiently maintained. In addition, when the concentration of the conductive fine particles in the anisotropic conductive film was increased, no leakage occurred between the electrodes until the concentration reached 40%.

Example 11 A test was conducted in the same manner as in Example 9 except that a copper ball having an aspect ratio of 1.13 and a CV value of 13% was used. The connection resistance value of this conductive connection structure was sufficiently 0.004Ω. The connection resistance between adjacent electrodes was 1 × 10 ⁹ or more, and the line insulation was sufficiently maintained. When the concentration of the conductive fine particles in the anisotropic conductive film was increased, no leakage occurred between the electrodes until the concentration reached 50%.

Example 12 A test was conducted in the same manner as in Example 9 except that a copper ball having an aspect ratio of 1.05 and a CV value of 8% was used. The connection resistance value of this conductive connection structure was sufficiently 0.002Ω. The connection resistance between adjacent electrodes was 1 × 10 ⁹ or more, and the line insulation was sufficiently maintained. When the concentration of the conductive fine particles in the anisotropic conductive film was increased, no leakage occurred between the electrodes until the concentration reached 60%.

Example 13 A test was conducted in the same manner as in Example 10 except that a copper ball having an average particle size of 4 μm was used. As a result, the connection resistance value of this conductive connection structure was sufficiently low at 0.006Ω, and the distance between adjacent electrodes was small. Had a connection resistance of 1 × 10 ⁹ or more, and the line insulation was sufficiently maintained. In addition, when the concentration of the conductive fine particles in the anisotropic conductive film was increased, no leakage occurred between the electrodes up to a concentration of 35%.

Example 14 Example 10 was repeated except that 0.4 μm copper particles were shot into copper spheres using a hybridizer to provide projections on the surface.
As a result of the test, the connection resistance value of this conductive connection structure was sufficiently low at 0.004Ω, the connection resistance between adjacent electrodes was 1 × 10 ⁹ or more, and the line insulation was sufficiently maintained. In addition, when the concentration of the conductive fine particles in the anisotropic conductive film was increased, no leakage occurred between the electrodes until the concentration reached 40%.

Example 15 A test was conducted in the same manner as in Example 10 except that a copper ball was coated with a thermoplastic vinyl copolymer resin of 1 μm. The connection resistance value of this conductive connection structure was sufficiently low at 0.006Ω. The connection resistance between adjacent electrodes was 1 × 10 ⁹ or more, and the line insulation was sufficiently maintained. When the concentration of the conductive fine particles in the anisotropic conductive film was increased, no leakage occurred between the electrodes until the concentration reached 60%.

Example 16 Anisotropic conductive paste was prepared by mixing and dispersing conductive fine particles of the present invention (copper spheres having an average particle diameter of 8 μm, an aspect ratio of 1.17 and a CV value of 20%) in an epoxy resin. This was applied to a glass-epoxy copper-clad substrate (thickness: 1.6 mm, wiring width: 50 μm, electrode pitch: 100 μm) to a substantially uniform thickness by a screen printing method. A thickness of 10
A polyimide film substrate of 0 μm (thickness 30 μm, wiring width 50 μm, electrode pitch 100 μm) is overlapped and
Heating and pressurization were performed at 50 ° C. for 2 minutes to produce a conductive connection structure.

The connection resistance value of this conductive connection structure is 0.0
06Ω, which is sufficiently low, and the connection resistance between adjacent electrodes is 1 × 1
With a value of ⁰⁹ or more, the line insulation was sufficiently maintained. In addition, when the concentration of the conductive fine particles in the anisotropic conductive paste was increased, no leakage occurred between the electrodes up to a concentration of 40%.

Comparative Example 7 A test was performed in the same manner as in Example 9 except that a copper ball having an aspect ratio of 1.2 and a CV value of 42% was used. The connection resistance value of this conductive connection structure was 0.03 Ω. Inferior to that of the invention, the connection resistance between adjacent electrodes is 1 × 10
^{Although the} line insulation was sufficiently maintained at ⁹ or more, when the concentration of the conductive fine particles in the anisotropic conductive film was increased,
Leakage between the electrodes occurred at a concentration of 30%.

Comparative Example 8 A test was conducted in the same manner as in Example 9 except that a copper ball having an aspect ratio of 1.6 and a CV value of 30% was used. The connection resistance value of this conductive connection structure was 0.02 Ω. Inferior to that of the invention, the connection resistance between adjacent electrodes is 1 × 10
^{Although the} line insulation was sufficiently maintained at ⁹ or more, when the concentration of the conductive fine particles in the anisotropic conductive film was increased,
Leakage between the electrodes occurred at a concentration of 30%.

Comparative Example 9 A test was conducted in the same manner as in Example 13 except that a copper ball having an aspect ratio of 1.2 and a CV value of 45% was used. The connection resistance value of this conductive connection structure was 0.02 Ω. Inferior to that of the invention, the connection resistance between adjacent electrodes is 1 × 1
Although the line insulating property was sufficiently maintained at a value of ⁰⁹ or more, when the concentration of the conductive fine particles in the anisotropic conductive film was increased, a leakage between the electrodes occurred at a concentration of 25%.

Comparative Example 10 Average particle size 200 μm, aspect ratio 1.05, CV value 8
When a test was conducted in the same manner as in Example 9 except that the copper ball was used in the same manner as in Example 9, particles settled at the stage of the binder solution, and an anisotropic conductive film could not be produced successfully.

Comparative Example 11 A test was conducted in the same manner as in Example 9 except that copper powder having a size of 0.2 μm or less was used. , Could not test well. Examples 9 to 16, Comparative Example 7
Table 2 shows the results of Nos. To 11.

[0072]

[Table 2]

Example 17 A nickel sphere having an average particle diameter of 8 μm, an aspect ratio of 1.2 and a CV value of 42% was dispersed in water at a concentration of 0.1%, and classification by drop speed was repeatedly performed to obtain a conductive material of the present invention. Functional fine particles (silver spheres having an average particle size of 8 μm, an aspect ratio of 1.2, and a CV value of 30%) were obtained. The conductive fine particles were mixed and dispersed in a binder solution obtained by dissolving a mixture of an epoxy resin and an acrylic resin in toluene. Next, the conductive fine particle dispersion solution was applied on the release film to a constant thickness, and toluene was evaporated to prepare an anisotropic conductive film. The film thickness is 30
μm, and the concentration of the conductive fine particles was 15%.

Glass-epoxy copper-clad substrate (thickness 1.6)
mm, a wiring width of 50 μm, and an electrode pitch of 100 μm). 100μm thick on this
Polyimide film substrate (thickness 30 μm, wiring width 50
μm, electrode pitch 100 μm)
The mixture was heated and pressurized at 2 ° C. for 2 minutes to produce a conductive connection structure.

The connection resistance value of this conductive connection structure is 0.0
15Ω sufficiently low, connection resistance between adjacent electrodes is 1 × 1
With a value of ⁰⁹ or more, the line insulation was sufficiently maintained. In general, when the concentration of the conductive fine particles in the anisotropic conductive film is increased, the electric resistance can be reduced. Therefore, when the concentration of the conductive fine particles is increased, the leakage between the electrodes is reduced to 40%. Did not occur.

Example 18 A test was conducted in the same manner as in Example 17 except that nickel balls having an aspect ratio of 1.17 and a CV value of 18% were used.
The connection resistance value of this conductive connection structure was sufficiently low at 0.009Ω, the connection resistance between adjacent electrodes was 1 × 10 ⁹ or more, and the line insulation was sufficiently maintained. Further, when the concentration of the conductive fine particles in the anisotropic conductive film was increased, the concentration became 45%.
%, No leak between the electrodes occurred.

Example 19 A test was conducted in the same manner as in Example 17 except that nickel balls having an aspect ratio of 1.13 and a CV value of 13% were used.
The connection resistance value of this conductive connection structure was sufficiently low at 0.006Ω, the connection resistance between adjacent electrodes was 1 × 10 ⁹ or more, and the line insulation was sufficiently maintained. When the concentration of the conductive fine particles in the anisotropic conductive film was increased, the concentration was 55%.
%, No leak between the electrodes occurred.

Example 20 A test was conducted in the same manner as in Example 17 except that nickel balls having an aspect ratio of 1.05 and a CV value of 8% were used. The connection resistance value of this conductive connection structure was sufficiently 0.003Ω. The connection resistance between adjacent electrodes was 1 × 10 ⁹ or more, and the line insulation was sufficiently maintained. When the concentration of the conductive fine particles in the anisotropic conductive film was increased, the concentration was 65%.
No leak occurred between the electrodes.

Example 21 A test was conducted in the same manner as in Example 18 except that a nickel sphere having an average particle size of 4 μm was used. As a result, the connection resistance value of this conductive connection structure was sufficiently low at 0.007Ω, and the connection between adjacent electrodes Had a connection resistance of 1 × 10 ⁹ or more, and the line insulation was sufficiently maintained. In addition, when the concentration of the conductive fine particles in the anisotropic conductive film was increased, no leakage occurred between the electrodes until the concentration reached 40%.

Example 22 A test was conducted in the same manner as in Example 18 except that 0.4 μm nickel particles were bombarded into nickel spheres using a hybridizer and projections were provided on the surface. The connection resistance of the conductive connection structure was measured. The value was as low as 0.007Ω, the connection resistance between adjacent electrodes was 1 × 10 ⁹ or more, and the line insulation was sufficiently maintained. In addition, when the concentration of the conductive fine particles in the anisotropic conductive film was increased, no leakage occurred between the electrodes until the concentration reached 40%.

Example 23 A test was conducted in the same manner as in Example 18 except that a nickel sphere was coated with a 1 μm thermoplastic vinyl copolymer resin. The connection resistance value of this conductive connection structure was 0.00
9Ω sufficiently low, connection resistance between adjacent electrodes is 1 × 10
^{With 9} or more, the line insulation was sufficiently maintained. Also, when the concentration of the conductive fine particles in the anisotropic conductive film was increased,
Leakage between the electrodes did not occur up to a concentration of 60%.

Example 24 The conductive fine particles of the present invention (nickel spheres having an average particle diameter of 8 μm, an aspect ratio of 1.17 and a CV value of 20%) were mixed and dispersed in an epoxy resin to prepare an anisotropic conductive paste. A glass-epoxy copper-clad substrate (thickness 1.6 mm,
(Wiring width 50 μm, electrode pitch 100 μm) was applied to a substantially uniform thickness by a screen printing method. Thickness 1 on this
A polyimide film substrate of 00 μm (thickness 30 μm, wiring width 50 μm, electrode pitch 100 μm) is overlapped,
Heating and pressurization were performed at 150 ° C. for 2 minutes to produce a conductive connection structure.

The connection resistance value of this conductive connection structure is 0.0
09 Ω, which is sufficiently low, and the connection resistance between adjacent electrodes is 1 × 1
With a value of ⁰⁹ or more, the line insulation was sufficiently maintained. When the concentration of the conductive fine particles in the anisotropic conductive paste was increased, no leakage occurred between the electrodes until the concentration reached 45%.

Comparative Example 12 Nickel spheres having an aspect ratio of 1.2 and a CV value of 42% (IN
A test was performed in the same manner as in Example 17 except that nickel powder 4SP manufactured by CO Co., Ltd. was used. The connection resistance value of this conductive connection structure was 0.04Ω, which was inferior to that of the present invention. The connection resistance between the electrodes is 1 × 10 ⁹
As described above, although the line insulation was sufficiently maintained, when the concentration of the conductive fine particles in the anisotropic conductive film was increased, a leak occurred between the electrodes at a concentration of 35%.

Comparative Example 13 A test was conducted in the same manner as in Example 17 except that a nickel sphere having an aspect ratio of 1.6 and a CV value of 30% was used. The connection resistance value of this conductive connection structure was 0.03 Ω. Inferior to that of the invention, the connection resistance between adjacent electrodes was 1 × 10 ⁹ or more, and the line insulation was sufficiently maintained, but the concentration of the conductive fine particles in the anisotropic conductive film was increased. Then, when the concentration was 35%, a leak occurred between the electrodes.

Comparative Example 14 Nickel spheres having an aspect ratio of 1.5 and a CV value of 40% (IN
Example 2 except that Ni♯123 manufactured by CO Co. was used.
When the test was conducted in the same manner as in Example 1, the connection resistance value of this conductive connection structure was 0.03Ω, which was inferior to that of the present invention, and the connection resistance between adjacent electrodes was 1 × 10 ⁹ or more, and the line insulation was Although the properties were sufficiently maintained, the concentration of the conductive fine particles in the anisotropic conductive film was increased to 30%.
Caused a leak between the electrodes.

Comparative Example 15 Average particle size 30 μm, aspect ratio 1.05, CV value 8%
When a test was conducted in the same manner as in Example 17 except that the nickel sphere was used, particles settled out at the stage of the binder solution, and an anisotropic conductive film could not be produced successfully.

Comparative Example 16 A test was conducted in the same manner as in Example 17 except that nickel powder having a size of 0.2 μm or less was used. , Could not test well. Example 17
To 24 and Comparative Examples 12 to 16 are shown in Table 3.

[0089]

[Table 3]

[0090]

According to the present invention, since it has the above-described structure, the connection resistance is low, the current capacity at the time of connection is large, the connection is stable, the conductive fine particles do not cause a leak phenomenon, and the anisotropic conductive adhesive. And a conductive connection structure.

Claims (10)

[Claims] 1. A conductive fine particle having a metal sphere as a nucleus, wherein said metal sphere has an average particle diameter of 0.3 to 25 μm, an aspect ratio of less than 1.5, and a CV value of 40% or less. Characteristic conductive fine particles. 2. The conductive fine particles according to claim 1, wherein the metal sphere has a CV value of 20% or less. 3. The conductive fine particles according to claim 1, wherein the metal sphere has an aspect ratio of less than 1.2. 4. The conductive fine particles according to claim 1, wherein the metal sphere has a CV value of 15% or less. 5. The conductive fine particles according to claim 1, wherein the metal sphere has a projection. 6. The conductive fine particles according to claim 1, wherein the metal sphere is coated with a resin. 7. The conductive fine particles according to claim 1, wherein the metal sphere is made of silver, copper, or nickel. 8. The conductive fine particles according to claim 7, wherein the metal sphere is made of copper produced by a chemical reduction method. 9. An anisotropic conductive adhesive comprising the conductive fine particles according to claim 1, 2, 3, or 8, and an insulating resin. 10. A conductive connection structure comprising the conductive fine particles according to claim 1, 2, 3, 4, 5, 6, 7, or 8.