WO2017138483A1 - 絶縁被覆導電粒子、異方導電性接着剤、及び接続構造体 - Google Patents
絶縁被覆導電粒子、異方導電性接着剤、及び接続構造体 Download PDFInfo
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- WO2017138483A1 WO2017138483A1 PCT/JP2017/004175 JP2017004175W WO2017138483A1 WO 2017138483 A1 WO2017138483 A1 WO 2017138483A1 JP 2017004175 W JP2017004175 W JP 2017004175W WO 2017138483 A1 WO2017138483 A1 WO 2017138483A1
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- 0 CC1C2(C(CC3C4)*(C)*2)C2C3C4C12 Chemical compound CC1C2(C(CC3C4)*(C)*2)C2C3C4C12 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J7/00—Adhesives in the form of films or foils
- C09J7/10—Adhesives in the form of films or foils without carriers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B5/00—Non-insulated conductors or conductive bodies characterised by their form
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
- C09C3/00—Treatment in general of inorganic materials, other than fibrous fillers, to enhance their pigmenting or filling properties
- C09C3/12—Treatment with organosilicon compounds
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
- C09J11/02—Non-macromolecular additives
- C09J11/04—Non-macromolecular additives inorganic
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J7/00—Adhesives in the form of films or foils
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J9/00—Adhesives characterised by their physical nature or the effects produced, e.g. glue sticks
- C09J9/02—Electrically-conducting adhesives
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/20—Conductive material dispersed in non-conductive organic material
- H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B5/00—Non-insulated conductors or conductive bodies characterised by their form
- H01B5/16—Non-insulated conductors or conductive bodies characterised by their form comprising conductive material in insulating or poorly conductive material, e.g. conductive rubber
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
- H01R11/00—Individual connecting elements providing two or more spaced connecting locations for conductive members which are, or may be, thereby interconnected, e.g. end pieces for wires or cables supported by the wire or cable and having means for facilitating electrical connection to some other wire, terminal, or conductive member, blocks of binding posts
- H01R11/01—Individual connecting elements providing two or more spaced connecting locations for conductive members which are, or may be, thereby interconnected, e.g. end pieces for wires or cables supported by the wire or cable and having means for facilitating electrical connection to some other wire, terminal, or conductive member, blocks of binding posts characterised by the form or arrangement of the conductive interconnection between the connecting locations
Definitions
- the present invention relates to an insulating coated conductive particle, an anisotropic conductive adhesive, and a connection structure.
- the method of mounting a liquid crystal driving IC on a glass panel for liquid crystal display can be roughly divided into two types: COG (Chip-on-Glass) mounting and COF (Chip-on-Flex) mounting.
- COG mounting a liquid crystal driving IC is directly bonded onto a glass panel using an anisotropic conductive adhesive containing conductive particles.
- COF mounting a liquid crystal driving IC is bonded to a flexible tape having metal wiring, and these are bonded to a glass panel using an anisotropic conductive adhesive containing conductive particles.
- anisotropic as used herein means that conduction is achieved in the pressurizing direction and insulation is maintained in the non-pressurizing direction.
- the metal bumps which are circuit electrodes of the liquid crystal driving IC
- the conductive particles of the anisotropic conductive adhesive may flow out between adjacent circuit electrodes and cause a short circuit. This tendency is particularly noticeable in COG mounting.
- the number of conductive particles in the anisotropic conductive adhesive located between the metal bump and the glass panel decreases. This increases the connection resistance between the circuit electrodes facing each other, which may cause a connection failure. Such a tendency becomes more remarkable when 20,000 particles / mm 2 or more of conductive particles are introduced per unit area.
- Patent Document 1 and Patent Document 2 propose a method of attaching spherical resin particles to the surface of conductive particles.
- Patent Document 1 also discloses a method of deforming insulating particles.
- Patent Documents 3 and 4 propose insulating coated conductive particles in which core-shell type resin particles are attached to the surface of the conductive particles.
- Patent Document 5 proposes composite particles in which hollow resin fine particles are attached to the surface of conductive particles.
- Patent Document 6 proposes insulating coated conductive particles in which first insulating particles and second insulating particles having a glass transition temperature lower than that of the first insulating particles are attached to the surface of the conductive particles.
- the average particle size of the first insulating particles is larger than 200 nm and 500 nm or less, and the average particle size of the second insulating particles is 50 nm or more and 200 nm or less.
- the Tg of the second insulating particles is as low as 80 to 120 ° C.
- the anisotropic conductive adhesive containing the insulating coating conductive particles when heated and pressurized, it melts and diffuses into the resin and disappears. .
- the particle concentration of the conductive particles when the particle concentration of the conductive particles is increased, the metal surface of the adjacent conductive particles easily comes into contact with the portion where the second insulating particles are melted and disappeared. .
- the present inventors have found that the first insulating particles having an average particle size of 200 nm or more and 500 nm or less and the average particle size of 30 nm or more and 130 nm or less. It has been found that the insulating coated conductive particles formed by attaching the second insulating particles made of silica to the surface of the conductive particles are used. Thereby, when the anisotropic conductive adhesive containing the insulating coating conductive particles is heated and pressurized, the second insulating particles made of silica are not melted and the metal surfaces of the adjacent conductive particles are prevented from coming into contact with each other.
- the second insulating particles have an average particle diameter of 30 nm or more and 130 nm or less, the connection resistance is not hindered by the second insulating particles, and excellent conduction reliability can be obtained even in connection of a minute circuit. I found out.
- An insulating coated conductive particle includes a conductive particle and a plurality of insulating particles attached to a surface of the conductive particle, and the average particle diameter of the conductive particle is 1 ⁇ m or more and 10 ⁇ m or less.
- the particles include first insulating particles having an average particle diameter of 200 nm to 500 nm and second insulating particles having an average particle diameter of 30 nm to 130 nm and made of silica.
- the glass transition temperature of the first insulating particles may be 100 ° C. or higher and 200 ° C. or lower.
- the coverage of the conductive particles by the first insulating particles and the second insulating particles may be 35 to 80% with respect to the total surface area of the conductive particles.
- the conductive particles may have protrusions on the surface.
- the second insulating particles are attached to the conductive particles on the smooth surface, even if the average particle size of the second insulating particles is 30 nm or more and 130 nm or less, the function as the insulating spacer of the second insulating particles is high, so that the insulation reliability The conductivity is excellent, but the conduction reliability tends to decrease. For this reason, when conductive particles have protrusions, a decrease in conduction reliability can be suppressed.
- the surface of the second insulating particles may be coated with a hydrophobizing agent.
- the surface of the conductive particles may be coated with a cationic polymer.
- the second insulating particles coated with the hydrophobizing agent are more likely to be negatively charged than the second insulating particles that are not hydrophobized, and are firmly attached to the conductive particles by static electricity. For this reason, it is possible to obtain insulating coated conductive particles having a high function as an insulating spacer and excellent in insulation reliability.
- the surface of the second insulating particles may be selected from the group consisting of a silazane hydrophobic treatment agent, a siloxane hydrophobic treatment agent, a silane hydrophobic treatment agent, and a titanate hydrophobic treatment agent.
- the hydrophobizing agent may be selected from the group consisting of hexamethylene disilazane (HMDS), polydimethylsiloxane (PDMS), and N, N-dimethylaminotrimethylsilane (DMATMS).
- HMDS hexamethylene disilazane
- PDMS polydimethylsiloxane
- DMATMS N, N-dimethylaminotrimethylsilane
- the degree of hydrophobicity of the second insulating particles by the methanol titration method may be 30% or more.
- the conductive particles may include resin particles and a metal layer covering the resin particles, and the metal layer may include a first layer containing nickel.
- the anisotropic conductive adhesive can achieve both excellent conduction reliability and insulation reliability.
- the metal layer may have a second layer provided on the first layer, and the second layer may contain a metal selected from the group consisting of noble metals and cobalt.
- the anisotropic conductive adhesive can achieve both excellent conduction reliability and insulation reliability.
- An anisotropic conductive adhesive according to another embodiment of the present invention includes the insulating coating conductive particles and an adhesive in which the insulating coating conductive particles are dispersed.
- the second insulating particles made of silica are not melted during heating and pressurization, and the metal surfaces of adjacent conductive particles are prevented from coming into contact with each other. Accordingly, even when charged with 100,000 / mm 2 or more of the conductive particles per unit area, it is possible to obtain an excellent insulation reliability.
- the second insulating particles have an average particle diameter of 30 nm or more and 130 nm or less, the connection resistance is not hindered by the second insulating particles, and excellent conduction reliability can be obtained even in connection of a minute circuit. It is.
- the adhesive may be in the form of a film.
- a connection structure includes a first circuit member having a first circuit electrode, a second circuit member facing the first circuit member and having a second circuit electrode, and a first circuit member. And the anisotropic conductive adhesive for bonding the second circuit member, the first circuit electrode and the second circuit electrode are opposed to each other and electrically connected to each other by the anisotropic conductive adhesive Is done.
- connection structure the first circuit member and the second circuit member are electrically connected to each other by the anisotropic conductive adhesive, thereby achieving both excellent conduction reliability and insulation reliability. it can.
- a connection structure includes a first circuit member having a first circuit electrode, a second circuit member facing the first circuit member and having a second circuit electrode, and a first circuit member. And a connection portion disposed between the first circuit electrode and the second circuit member, wherein the insulating coating conductive particles are dispersed in the connection portion, and the first circuit electrode and the second circuit electrode face each other. At the same time, they are electrically connected to each other through the insulating coated conductive particles in a deformed state.
- connection structure the first circuit member and the second circuit member are electrically connected to each other by the insulating coating conductive particles dispersed in the connection portion, thereby achieving both excellent conduction reliability and insulation reliability. can do.
- insulating coated conductive particles capable of achieving both excellent insulation reliability and conduction reliability even in connection of a minute circuit.
- an anisotropic conductive adhesive and a connection structure using the insulating coated conductive particles can be provided.
- FIG. 1 is a schematic cross-sectional view showing insulating coated conductive particles according to the first embodiment.
- FIG. 2 is a schematic cross-sectional view showing insulating coated conductive particles according to the second embodiment.
- FIG. 3 is a schematic cross-sectional view showing insulating coated conductive particles according to the third embodiment.
- FIG. 4 is a schematic cross-sectional view showing insulating coated conductive particles according to the fourth embodiment.
- FIG. 5 is a schematic cross-sectional view showing the connection structure according to the sixth embodiment.
- FIG. 6 is a schematic cross-sectional view for explaining an example of the manufacturing method of the connection structure according to the sixth embodiment.
- FIG. 7 is an SEM image obtained by observing particles obtained after step d in the production of the conductive particles of Example 1.
- FIG. 7 is an SEM image obtained by observing particles obtained after step d in the production of the conductive particles of Example 1.
- FIG. 8 is an SEM image obtained by observing the particles obtained after step d in the production of the conductive particles of Example 1.
- FIG. 9 is an SEM image obtained by observing the particles obtained in step f in the production of the conductive particles of Example 1.
- FIG. 10 is an SEM image obtained by observing the surface of the particles obtained in step f in the production of the conductive particles of Example 1.
- FIG. 11 is a schematic diagram for explaining the trimming process.
- FIG. 12 is a schematic diagram for explaining a method of producing a thin film slice for TEM measurement.
- FIG. 13 is an SEM image obtained by observing the insulating coated conductive particles obtained in step i of Example 1.
- 14 is an SEM image obtained by observing the insulating coated conductive particles obtained in step i of Example 1.
- FIG. 15 is an SEM image obtained by observing the insulating coated conductive particles obtained in step i of Example 7.
- FIG. 16 is an SEM image obtained by observing the insulating coated conductive particles obtained in step i of Example 7.
- FIG. 17 is an SEM image obtained by observing the surface of the insulating coated conductive particles obtained in Comparative Example 1.
- FIG. 1 is a schematic cross-sectional view showing insulating coated conductive particles according to the first embodiment. 1 covers the resin particles 101 constituting the core of the conductive particles 1, the nonconductive inorganic particles 102 adhering to the resin particles 101, and the resin particles 101 and the nonconductive inorganic particles 102.
- a first layer 104 that is a metal layer and insulating particles 210 attached to the first layer 104 are provided.
- a protrusion 109 reflecting the shape of the non-conductive inorganic particles 102 adhered to the resin particles 101 is formed.
- the first layer 104 is a conductive layer containing at least a metal.
- the first layer 104 may be a metal layer or an alloy layer.
- the insulating particles 210 include first insulating particles 210a having an average particle diameter of 200 nm to 500 nm and second insulating particles 210b having an average particle diameter of 30 nm to 130 nm and made of silica.
- the average particle diameter of the insulating coated conductive particles 100a may be, for example, 1 ⁇ m or more, or 2 ⁇ m or more.
- the average particle diameter of the insulating coated conductive particles 100a may be, for example, 10 ⁇ m or less, or 5 ⁇ m or less. That is, the average particle diameter of the insulating coated conductive particles 100a is, for example, 1 to 10 ⁇ m.
- the average particle diameter of the insulating coated conductive particles 100a is an average value obtained by measuring the particle diameter of 300 arbitrary insulating coated conductive particles by observation using a scanning electron microscope (hereinafter referred to as "SEM"). It is good.
- the particle diameter of the insulating coated conductive particles 100a is a diameter of a circle circumscribing the insulating coated conductive particles 100a in an image taken by SEM.
- a commercially available apparatus such as a Coulter counter can be used.
- the average particle diameter can be measured with high accuracy by measuring the particle diameter of 50000 insulating coated conductive particles.
- the average particle diameter of the insulating coated conductive particles 100a may be measured by measuring 50,000 insulating coated conductive particles by COULER MULTISIZER II (trade name, manufactured by Beckman Coulter, Inc.).
- the monodispersion rate of the insulating coated conductive particles 100a may be 96.0% or more, or 98.0% or more. When the monodispersion rate of the insulating coated conductive particles 100a is within the above range, for example, high insulation reliability can be obtained after a moisture absorption test.
- the monodispersion rate of the insulating coated conductive particles 100a can be measured by, for example, COULER MULTISIZER II (trade name, manufactured by Beckman Coulter, Inc.) using 50,000 conductive particles.
- the resin particles 101 are made of an organic resin.
- the organic resin include (meth) acrylic resins such as polymethyl methacrylate and polymethyl acrylate; polyolefin resins such as polyethylene and polypropylene; polyisobutylene resins; and polybutadiene resins.
- the resin particles 101 particles obtained by crosslinking organic resins such as crosslinked (meth) acrylic particles and crosslinked polystyrene particles can also be used.
- the resin particles may be composed of one kind of the organic resin or a combination of two or more kinds of the organic resin.
- the organic resin is not limited to the above resin.
- Resin particles 101 are spherical.
- the average particle diameter of the resin particles 101 may be, for example, 1 ⁇ m or more and 10 ⁇ m or less.
- the average particle diameter of the resin particles 101 may be, for example, 1 ⁇ m or more, or 2 ⁇ m or more.
- the average particle diameter of the resin particles 101 may be, for example, 10 ⁇ m or less, or 5 ⁇ m or less.
- the average particle diameter of the resin particles 101 is an average value obtained by measuring the particle diameter of 300 arbitrary resin particles by observation using an SEM.
- the resin particles 101 may be coated with a cationic polymer as a surface treatment.
- the cationic polymer generally include a polymer compound having a functional group capable of being positively charged, such as polyamine.
- the cationic polymer may be selected from the group consisting of, for example, polyamine, polyimine, polyamide, polydiallyldimethylammonium chloride, polyvinylamine, polyvinylpyridine, polyvinylimidazole, and polyvinylpyrrolidone.
- Polyimine is preferable and polyethyleneimine is more preferable from the viewpoint of high charge density and strong binding force to negatively charged surfaces and materials.
- the cationic polymer is preferably soluble in water or a mixed solution of water and an organic solvent.
- the molecular weight of the cationic polymer varies depending on the type of the cationic polymer used, but is, for example, about 500 to 200,000.
- the coverage of the resin particles 101 with the non-conductive inorganic particles 102 can be controlled. Specifically, when the resin particles 101 are coated with a cationic polymer having a high charge density such as polyethyleneimine, the coverage of the nonconductive inorganic particles 102 (the ratio of the nonconductive inorganic particles 102 covering the resin particles 101) ) Tends to be high. On the other hand, when the resin particles 101 are coated with a cationic polymer having a low charge density, the coverage of the non-conductive inorganic particles 102 tends to be low.
- the coverage of the non-conductive inorganic particles 102 tends to be high, and when the molecular weight of the cationic polymer is small, the coverage of the non-conductive inorganic particles 102 tends to be low. is there.
- Cationic polymers include alkali metal (Li, Na, K, Rb, Cs) ion, alkaline earth metal (Ca, Sr, Ba, Ra) ion, and halide ion (fluorine ion, chloride ion, bromine ion, iodine). Ions) may be substantially absent. In this case, electromigration and corrosion of the resin particles 101 coated with the cationic polymer are suppressed.
- the resin particles 101 before being coated with the cationic polymer have a functional group selected from a hydroxyl group, a carboxyl group, an alkoxy group, a glycidyl group and an alkoxycarbonyl group on the surface. Thereby, the cationic polymer is easily adsorbed on the surface of the resin particle 101.
- the non-conductive inorganic particle 102 is a particle that becomes the core of the protrusion 109 and is adhered to the resin particle 101 by, for example, electrostatic force.
- the shape of the non-conductive inorganic particles 102 is not particularly limited, but may be an ellipsoid, a sphere, a hemisphere, a substantially ellipsoid, a substantially sphere, a substantially hemisphere, or the like. Among these, an ellipsoid or a sphere is preferable.
- the material forming the non-conductive inorganic particles 102 may be harder than the material forming the first layer 104. Thereby, it becomes easy for the conductive particles to pierce the electrode or the like, and the conductivity is improved. That is, the idea is not to harden the entire conductive particles but to harden some of the conductive particles.
- the Mohs hardness of the material forming the non-conductive inorganic particles 102 is larger than the Mohs hardness of the metal forming the first layer 104. Specifically, the Mohs hardness of the material forming the non-conductive inorganic particles 102 is 5 or more.
- the difference between the Mohs hardness of the material forming the non-conductive inorganic particles 102 and the Mohs hardness of the metal forming the first layer 104 may be 1.0 or more.
- the Mohs hardness of the non-conductive inorganic particles 102 may be higher than the Mohs hardness of all metals.
- materials for forming the non-conductive inorganic particles 102 are silica (silicon dioxide (SiO 2 ), Mohs hardness 6-7), zirconia (Mohs hardness 8-9), alumina (Mohs hardness 9), and diamond. You may select from the group which consists of (Mohs hardness 10).
- the surface of the non-conductive inorganic particles 102 may be coated with a hydrophobizing agent so that hydroxyl groups (—OH) are formed.
- the hydrophobizing agent may be the same as that used in the hydrophobizing treatment performed on the second insulating particles 210b (details will be described later).
- the value of the Mohs hardness was referred to “Chemical Dictionary” (published by Kyoritsu Shuppan Co., Ltd.).
- silica particles are used as the non-conductive inorganic particles 102.
- the particle size of the silica particles is preferably controlled.
- the average particle diameter of the non-conductive inorganic particles 102 is, for example, 25 nm to 120 nm, or about 1/120 to 1/10 of the average particle diameter of the resin particles 101.
- the average particle diameter of the non-conductive inorganic particles 102 may be 30 nm to 100 nm, or may be 35 nm to 80 nm.
- the protrusions 109 of the first layer 104 tend to have an appropriate size and the resistance tends to be reduced.
- the non-conductive inorganic particles 102 are less likely to drop off in an electroless nickel plating step, a pretreatment for electroless nickel plating, and the like described later. As a result, the number of protrusions 109 becomes sufficient, and the resistance tends to be reduced.
- the metal of the first layer 104 covers the aggregated pieces of the non-conductive inorganic particles 102 that have fallen and become metal foreign matter. The metal foreign matter may reattach to the resin particles 101, and an excessively long protrusion (for example, a protrusion having a length exceeding 500 nm) may be formed as an abnormal precipitation portion.
- the insulation reliability of the insulation-coated conductive particles 100a may be a factor of deterioration. Furthermore, the metal foreign matter itself may cause a decrease in insulation reliability. Therefore, it is preferable to prevent the non-conductive inorganic particles 102 from dropping from the resin particles 101.
- the particle size of the non-conductive inorganic particles 102 is measured by, for example, a specific surface area conversion method by the BET method or an X-ray small angle scattering method.
- Adhesion of the non-conductive inorganic particles 102 to the resin particles 101 can be performed using an organic solvent or a mixed solution of water and a water-soluble organic solvent.
- water-soluble organic solvents examples include methanol, ethanol, propanol, acetone, dimethylformamide, and acetonitrile.
- the non-conductive inorganic particles 102 and the resin particles 101 may be joined by electrostatic force by coating the non-conductive inorganic particles 102 with a hydrophobic treatment agent and coating the resin particles 101 with a cationic polymer.
- the metal layer that covers the composite particles 103 may have a single-layer structure or a stacked structure having a plurality of layers.
- the first layer 104 may be a plating layer.
- the first layer 104 may be a conductive layer containing nickel as a main component from the viewpoints of cost, conduction reliability, and corrosion resistance. Considering the flatness of electrodes provided on glass in recent years, the first layer 104 may be provided so that the surface thereof has a protrusion 109 in order to improve conduction reliability.
- the thickness of the first layer 104 is, for example, 40 nm to 200 nm. When the thickness of the first layer 104 is within the above range, cracking of the first layer 104 can be suppressed even when the conductive particles 1 are compressed. Further, the surface of the composite particle 103 can be sufficiently covered with the first layer 104. As a result, the non-conductive inorganic particles 102 can be fixed to the resin particles 101, and the non-conductive inorganic particles 102 can be prevented from falling off. As a result, it is possible to form projections 109 having good shapes at high density on each of the obtained conductive particles 1.
- the thickness of the first layer 104 may be 60 nm or more.
- the thickness of the first layer 104 may be 150 nm or less, or 120 nm or less.
- the first layer 104 may have a single layer structure or a stacked structure. In the present embodiment, the first layer 104 has a two-layer structure.
- the thickness of the first layer 104 is calculated using a photograph taken with a transmission electron microscope (hereinafter referred to as “TEM”). As a specific example, first, a cross section of the conductive particle 1 is cut out by an ultramicrotome method so as to pass near the center of the conductive particle 1. Next, the cut section is observed at a magnification of 250,000 times using a TEM to obtain an image. Next, the thickness of the first layer 104 can be calculated from the cross-sectional area of the first layer 104 estimated from the obtained image.
- TEM transmission electron microscope
- the thickness of the first layer 104 is an average value of the thickness of 10 conductive particles.
- the first layer 104 may contain at least one selected from the group consisting of phosphorus and boron in addition to the metal whose main component is nickel. Thereby, the hardness of the first layer 104 containing nickel can be increased, and the conduction resistance when the conductive particles 1 are compressed can be easily kept low.
- the first layer 104 may contain a eutectoid metal together with phosphorus or boron.
- the metal contained in the first layer 104 is, for example, cobalt, copper, zinc, iron, manganese, chromium, vanadium, molybdenum, palladium, tin, tungsten, and rhenium.
- the first layer 104 can increase the hardness of the first layer 104 by containing nickel and the above metal.
- the metal may include tungsten having a high hardness.
- the constituent material of the first layer 104 include a combination of nickel (Ni) and phosphorus (P), a combination of nickel (Ni) and boron (B), nickel (Ni), tungsten (W), and boron (B). And a combination of nickel (Ni) and palladium (Pd).
- a phosphorus-containing compound such as sodium hypophosphite may be used as a reducing agent.
- phosphorus can be co-deposited, and the first layer 104 containing a nickel-phosphorus alloy can be formed.
- the reducing agent boron-containing compounds such as dimethylamine borane, sodium borohydride, potassium borohydride and the like may be used.
- boron can be co-deposited, and the first layer 104 containing a nickel-boron alloy can be formed.
- the hardness of the nickel-boron alloy is higher than that of the nickel-phosphorus alloy. Therefore, when a boron-containing compound is used as the reducing agent, the protrusion 109 formed on the non-conductive inorganic particles 102 can be suppressed from being crushed even when the insulating coated conductive particles 100a are compressed.
- the first layer 104 may have a concentration gradient in which the nickel concentration (content) increases as the distance from the surface of the composite particle 103 increases. With such a configuration, a low conduction resistance can be maintained even when the insulating coated conductive particles 100a are compressed.
- This concentration gradient may be continuous or discontinuous.
- the concentration gradient of nickel is discontinuous, a plurality of layers having different nickel contents may be provided as the first layer 104 on the surface of the composite particle 103. In this case, the nickel concentration of the layer provided on the side far from the composite particle 103 is increased.
- the nickel content in the first layer 104 increases as the surface approaches the surface in the thickness direction of the first layer 104.
- the nickel content in the surface layer of the first layer 104 is, for example, 99 mass% to 97 mass%.
- the thickness of the surface side layer is, for example, 5 to 60 nm.
- the thickness of the layer may be 10 to 50 nm or 15 to 40 nm.
- the connection resistance value of the first layer 104 tends to be low.
- the thickness of the surface-side layer is 60 nm or less, the monodispersion rate of the conductive particles 1 tends to be further improved.
- the first layer 104 it is easy to lower the resistance of the conductive particles 1, further suppress the aggregation of the conductive particles 1, and easily obtain high insulation reliability.
- a layer having a nickel content of 97% by mass or less may be formed on the composite particle 103 side.
- the nickel content of the layer on the composite particle 103 side may be 95% by mass or less, or 94% by mass or less.
- the thickness of the layer on the composite particle 103 side may be 20 nm or more, 40 nm or more, or 50 nm or more.
- the conductive particles 1 are not easily affected by magnetism, and aggregation of the conductive particles 1 tends to be suppressed. is there.
- the kind of element and the content of the element in the first layer 104 can be measured by, for example, cutting out a cross section of the conductive particle by an ultramicrotome method and then performing component analysis by EDX attached to the TEM.
- the first layer 104 is formed by electroless nickel plating.
- the electroless nickel plating solution contains a water-soluble nickel compound.
- the electroless nickel plating solution may further contain at least one compound selected from the group consisting of a stabilizer (for example, bismuth nitrate), a complexing agent, a reducing agent, a pH adjusting agent, and a surfactant.
- water-soluble nickel compound water-soluble nickel inorganic salts such as nickel sulfate, nickel chloride and nickel hypophosphite; water-soluble nickel organic salts such as nickel acetate and nickel malate are used.
- a water-soluble nickel compound can be used individually by 1 type or in combination of 2 or more types.
- the concentration of the water-soluble nickel compound in the electroless nickel plating solution is preferably 0.001 to 1 mol / L, and more preferably 0.01 to 0.3 mol / L.
- concentration of the water-soluble nickel compound is within the above range, it is possible to sufficiently obtain the deposition rate of the plating film, and to suppress the viscosity of the plating solution from becoming too high, thereby improving the uniformity of nickel deposition. Can do.
- any complexing agent may be used as long as it functions as a complexing agent.
- ethylenediaminetetraacetic acid; sodium salt of ethylenediaminetetraacetic acid (for example, 1-, 2-, 3- and 4-sodium salts) Ethylenediaminetriacetic acid; nitrotetraacetic acid, alkali salts thereof; glyconic acid, tartaric acid, gluconate, citric acid, gluconic acid, succinic acid, pyrophosphoric acid, glycolic acid, lactic acid, malic acid, malonic acid, alkali salts thereof (for example, sodium Salt); triethanolamine glucono ( ⁇ ) -lactone and the like.
- a complexing agent can be used individually by 1 type or in combination of 2 or more types.
- the concentration of the complexing agent in the electroless nickel plating solution is usually preferably 0.001 to 2 mol / L, and more preferably 0.002 to 1 mol / L.
- concentration of the complexing agent is within the above range, it is possible to obtain a sufficient deposition rate of the plating film while suppressing precipitation of nickel hydroxide in the plating solution and decomposition of the plating solution, and the viscosity of the plating solution. Can be prevented from becoming too high, and the uniformity of nickel deposition can be improved.
- the concentration of the complexing agent may vary depending on the type.
- reducing agent a known reducing agent used for an electroless nickel plating solution can be used.
- the reducing agent include hypophosphite compounds such as sodium hypophosphite and potassium hypophosphite; borohydride compounds such as sodium borohydride, potassium borohydride and dimethylamine borane; hydrazines and the like. .
- the concentration of the reducing agent in the electroless nickel plating solution is usually preferably 0.001 to 1 mol / L, and more preferably 0.002 to 0.5 mol / L.
- concentration of the reducing agent is within the above range, decomposition of the plating solution can be suppressed while sufficiently obtaining a nickel ion reduction rate in the plating solution.
- concentration of the reducing agent may vary depending on the type of the reducing agent.
- Examples of the pH adjuster include an acidic pH adjuster and an alkaline pH adjuster.
- Acidic pH adjusters include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, acetic acid, formic acid, cupric chloride, iron compounds such as ferric sulfate, alkali metal chlorides, ammonium persulfate, and aqueous solutions containing one or more of these.
- An aqueous solution containing acidic hexavalent chromium such as chromic acid, chromic acid-sulfuric acid, chromic acid-hydrofluoric acid, dichromic acid, dichromic acid-borofluoric acid, and the like.
- alkaline pH adjusters examples include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, and sodium carbonate; alkaline earth metal hydroxides; amino groups such as ethylenediamine, methylamine, and 2-aminoethanol. Compounds containing; solutions containing one or more of these may be mentioned.
- a cationic surfactant an anionic surfactant, an amphoteric surfactant, a nonionic surfactant, a mixture thereof, or the like can be used.
- the composite particles 103 may be preliminarily treated with a palladium catalyst.
- the palladium catalyst treatment can be performed by a known method.
- the pretreatment may be performed by a catalytic treatment method using a catalytic treatment liquid called an alkali seeder or an acidic seeder.
- a protrusion 109 reflecting the shape of the non-conductive inorganic particle 102 is formed on the surface of the conductive particle 1 (specifically, the surface of the first layer 104).
- the protrusion 109 including the non-conductive inorganic particle 102 and the first layer 104 is a first protrusion having a diameter (outer diameter) of less than 100 nm.
- the ratio of the first protrusion to the total number of protrusions may be less than 80%, the ratio of the second protrusion to the total number of protrusions may be 20 to 80%, and the ratio of the third protrusion to the total number of protrusions may be 10% or less.
- the ratio of the first protrusion to the total number of protrusions may be less than 60%, the ratio of the second protrusion to the total number of protrusions may be 40 to 70%, and the ratio of the third protrusion to the total number of protrusions may be 5% or less.
- the insulating coated conductive particles 100a in which the ratio of the first to third protrusions in the total number of protrusions is within the above range has excellent conduction reliability when used as the insulating coated conductive particles blended in the anisotropic conductive adhesive. And the reliability of insulation can be achieved at a higher level.
- the “total number of protrusions” is the total number of protrusions present in concentric circles having a diameter that is 1 ⁇ 2 of the diameter of the conductive particles.
- the area of the protrusion 109 in the conductive particle 1 is the area of the protrusion 109 in a concentric circle having a diameter that is 1 ⁇ 2 of the diameter of the conductive particle 1 on the orthographic projection surface of the conductive particle 1 (due to the valley between adjacent protrusions 109. It means the area of the outline of each projection 109 to be separated.
- the diameter (outer diameter) of the protrusion 109 is calculated for the protrusion 109 existing in a concentric circle having a diameter that is 1 ⁇ 2 of the diameter of the conductive particle 1 on the orthographic projection surface of the conductive particle 1, and is the same as the area of the protrusion 109.
- the diameter of a perfect circle having an area of Specifically, an image obtained by observing the conductive particles 1 at a magnification of 30,000 with an SEM is analyzed, and the contour of the protrusion 109 is defined to determine the area of each protrusion.
- the protrusion 109 may be included in a concentric circle having a diameter that is 1/2 of the diameter of the conductive particle on the orthographic projection surface of the conductive particle as follows.
- the number of protrusions in the concentric circles may be, for example, 50 or more, 70 or more, or 90 or more.
- the number of protrusions in the concentric circles may be, for example, 250 or less, 220 or less, or 200 or less.
- the area ratio (coverage) of the protrusion 109 may be, for example, 60% or more, 80% or more, or 90% or more. When the coverage of the protrusions 109 is 60% or more, the conduction resistance is unlikely to increase even when the conductive particles 1 are placed under high humidity.
- the ratio (coverage) of the area of the protrusion 109 is 1 / of the diameter of the conductive particle 1 with the total area of concentric circles having a diameter of 1/2 of the diameter of the conductive particle 1 on the orthographic projection surface of the conductive particle 1 as the denominator.
- the sum of the areas of the protrusions 109 in the concentric circles having a diameter of 2 can be expressed as a 100-percent fraction calculated as a numerator.
- Examples of a method for forming the protrusion 109 on the surface of the conductive particle 1 include a method using abnormal deposition of plating and a method using a core material.
- the core material may be, for example, a conductive material such as nickel, carbon, palladium, or gold, or may be a nonconductive material such as plastic, silica, or titanium oxide.
- the core material When a non-magnetic material is used for the core material, magnetic aggregation does not occur at the stage of covering the insulating particles 210, and the insulating particles 210 tend to adhere to the conductive particles 1 easily. For this reason, when nickel which is a ferromagnetic material is used as the core material, the core material may further include a nonmagnetic material such as phosphorus.
- a method for forming the protrusion 109 a method using the non-conductive inorganic particles 102 as a core material is used as . Accordingly, the size of the protrusion 109 can be controlled, and the protrusion 109 having a good shape can be formed. Therefore, both insulation reliability and conduction reliability can be achieved.
- the non-conductive inorganic particles 102 even when the conductive particles 1 are highly compressed, the first layer 104 constituting the protrusions 109 formed on the non-conductive inorganic particles 102 is crushed. It is suppressed. For this reason, for example, even when silica is used as the insulating particles 210, the first layer 104 can be prevented from being crushed and a low conduction resistance can be obtained when crimped to an electrode or the like.
- the insulating particles 210 include the first insulating particles 210a having an average particle diameter of 200 nm to 500 nm and the second insulating particles 210b having an average particle diameter of 30 nm to 130 nm and made of silica. .
- the average particle diameter of the first insulating particles 210a is not less than 200 nm and not more than 500 nm.
- the 1st insulating particle 210a fully functions as an insulating spacer, and more excellent insulation reliability is obtained.
- the average particle diameter of the first insulating particles 210a is 500 nm or less, the first insulating particles 210a can be easily attached to the conductive particles 1.
- the shape of the first insulating particle 210a is not particularly limited, but is an ellipsoid, a sphere, a hemisphere, a substantially ellipsoid, a substantially sphere, a substantially hemisphere, or the like. Among these, an ellipsoid or a sphere is preferable.
- the variation in the particle diameter of the first insulating particles 210a may be, for example, 10% or less, or 3% or less.
- CV in this specification means the ratio of the standard deviation of the particle diameter to the average particle diameter expressed as a percentage.
- the average particle diameter of the first insulating particles 210 a is desirably larger than the diameter of the protrusions 109 from the viewpoint of easily attaching the first insulating particles 210 a to the conductive particles 1.
- the first insulating particles 210a are, for example, fine particles composed of an organic polymer compound.
- the organic polymer compound a compound having heat softening properties is preferable.
- Specific examples of the organic polymer compound include polyethylene, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester copolymer, polyester, polyamide, polyurethane, Polystyrene, styrene-divinylbenzene copolymer, styrene-isobutylene copolymer, styrene-butadiene copolymer, styrene- (meth) acrylic acid copolymer, ethylene-propylene copolymer, (meth) acrylic acid ester rubber Styrene-ethylene-butylene copolymer, phenoxy resin, solid epoxy resin and the like are used.
- An organic polymer compound can be used individually by 1 type or in
- organic-inorganic hybrid particles such as a copolymer of silicon-containing monomer and acrylic may be used as the first insulating particles 210a.
- Examples of the method for producing the first insulating particles 210a include soap-free emulsion polymerization.
- the first insulating particles 210a may be a copolymer using a monomer composition containing an alkoxysilane having a double bond between carbons in order to improve reliability.
- alkoxysilane examples include 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-acryloxypropyltrimethoxy. Silane etc. are mentioned. Of these, 3-methacryloxypropyltrimethoxysilane is preferably used.
- the content of alkoxysilane having a carbon-carbon double bond is preferably 0.5 mol% to 5 mol% with respect to the total amount of the monomer composition.
- radical polymerization initiators used in producing the first insulating particles 210a include benzoyl peroxide, t-butylbenzoate, potassium peroxodisulfate, 1,1-azobis (cyclohexane-1-carbonitrile), 2,2 -Azobisisobutyronitryl and the like.
- the radical polymerization initiator is not limited to these.
- the first insulating particles 210a can be synthesized more stably, and the particle size can be controlled more easily.
- the hydrophilic monomer include sodium styrene sulfonate, methacrylic acid, sodium methacrylate and the like.
- the content of the hydrophilic monomer is preferably 0.1 mol% to 30 mol% with respect to the total amount of the monomer composition.
- the glass transition temperature (hereinafter also referred to as Tg) of the first insulating particles 210a can be adjusted by adding a concentration of a crosslinking material or a component such as an alkyl acrylate. By adding the cross-linking material, the Tg of the first insulating particles 210a tends to increase. Moreover, Tg of the 1st insulating particle 210a can be lowered
- the Tg of the first insulating particles 210a is, for example, 100 ° C. to 200 ° C.
- the glass transition temperature of each particle including the first insulating particles 210a is increased by using a differential scanning calorimeter (DSC, for example, trade name “DSC-7” manufactured by PerkinElmer Co., Ltd.) Measurement was performed under conditions of a temperature rate of 5 ° C./min and a measurement atmosphere: air.
- DSC differential scanning calorimeter
- the crosslinking agent increases the Tg of the first insulating particles 210a and also improves the solvent resistance and heat resistance of the first insulating particles 210a.
- Specific examples of the crosslinking agent include divinylbenzene, diacrylate and the like.
- the content of the crosslinking agent is, for example, 0 mol% to 10 mol% with respect to the total monomers of the first insulating particles 210a. Further, in view of characteristics, the content of the crosslinking agent may be 1 mol% to 5 mol%.
- Soap-free emulsion polymerization methods are well known to those skilled in the art.
- a monomer for synthesis, water, and a polymerization initiator are placed in a flask, and the emulsion polymerization is performed with stirring at a stirring speed of 100 to 500 min ⁇ 1 (100 to 500 rpm) in a nitrogen atmosphere.
- the total monomer content is, for example, 1% by mass to 20% by mass with respect to the solvent water.
- the polymerization temperature of soap-free emulsion polymerization is, for example, 40 ° C. to 90 ° C., and the polymerization time is 2 hours to 15 hours. An appropriate polymerization temperature and time can be appropriately selected.
- the average particle diameter of the second insulating particles 210b is not less than 30 nm and not more than 130 nm.
- the average particle diameter of the second insulating particles 210b may be larger than 25 nm or 100 nm or less.
- the second insulating particles 210b sufficiently function as an insulating spacer, and better insulation reliability can be obtained.
- the average particle size of the second insulating particles 210b is 130 nm or less, the second insulating particles 210b can be easily attached to the conductive particles 1.
- the shape of the second insulating particles 210b is not particularly limited, and is, for example, an ellipsoid, a sphere, a hemisphere, a substantially ellipsoid, a substantially sphere, a substantially hemisphere, or the like. Among these, an ellipsoid or a sphere is preferable.
- the variation in the particle size (hereinafter also referred to as CV) of the second insulating particles 210b may be, for example, 10% or less, or 3% or less.
- CV the variation in the particle size of the second insulating particles 210b
- the conduction reliability and the insulation reliability can be improved.
- Silica (SiO 2 ) particles may be used as the second insulating particles 210b.
- the particle size of the silica particles is preferably controlled.
- the type of silica particles is not particularly limited, and examples thereof include colloidal silica, fumed silica, and sol-gel silica.
- Silica particles may be used alone or in combination of two or more.
- As the silica particles a commercially available product or a synthetic product may be used.
- colloidal silica As a method for producing colloidal silica, known methods may be mentioned. Specifically, a method by hydrolysis of alkoxysilane described in pages 154 to 156 of “Science of Sol-Gel Process” (Sakuo Sakuo, published by Agne Sefu Co., Ltd.); JP-A-11-60232 A method of reacting methyl silicate and water by dropping methyl silicate or a mixture of methyl silicate and methanol into water, methanol and a mixed solvent composed of ammonia or ammonia and an ammonium salt, as described in 1.
- Examples of commercially available water-dispersed colloidal silica include Snowtex, Snowtex UP (both manufactured by Nissan Chemical Industries, Ltd., trade name), Quatron PL series (manufactured by Fuso Chemical Industries, Ltd., trade name), and the like.
- fumed silica As a method for producing fumed silica, a known method using a gas phase reaction in which silicon tetrachloride is vaporized and burned in an oxyhydrogen flame can be mentioned. Furthermore, fumed silica can be made into an aqueous dispersion by a known method. Examples of the method for preparing an aqueous dispersion include the methods described in JP-A No. 2004-43298, JP-A No. 2003-176123, JP-A No. 2002-309239, and the like. From the viewpoint of the insulation reliability of fumed silica, the concentration of alkali metal ions and alkaline earth metal ions in the aqueous dispersion is preferably 100 ppm or less. The Mohs hardness of fumed silica may be 5 or more, or 6 or more.
- a method for attaching the insulating particles 210 to the conductive particles 1 is not particularly limited.
- the method etc. which adhere the insulating particle 210 with a functional group to the electrically conductive particle 1 with a functional group are mentioned.
- the insulating particle 210 has a functional group having good reactivity such as a hydroxyl group, a silanol group, and a carboxyl group on the outer surface.
- a functional group such as a hydroxyl group, a carboxyl group, an alkoxy group, or an alkoxycarbonyl group may be formed on the surface of the conductive particle 1.
- a strong bond such as a covalent bond or a hydrogen bond based on dehydration condensation can be formed by the functional group and the functional group on the surface of the insulating particle 210. .
- the first layer 104 containing nickel as a main component is the surface.
- a hydroxyl group, a carboxyl group, an alkoxyl group, and an alkoxycarbonyl group are formed on the surface of the first layer 104 by using a compound having a silanol group or a hydroxyl group that forms a strong bond with nickel, or a nitrogen compound. It is preferable to introduce one or more functional groups selected from the group consisting of: Specifically, carboxybenzotriazole or the like is used.
- the method for treating the surface of the first layer 104 with the above compound is not particularly limited.
- the surface potential (zeta potential) of the conductive particles 1 having at least one selected from the group consisting of a hydroxyl group, a carboxyl group, an alkoxyl group, and an alkoxycarbonyl group on the surface is usually negative when the pH is in a neutral region.
- the surface potential of the insulating particle 210 having a hydroxyl group is usually negative.
- a polymer electrolyte layer may be provided therebetween. Thereby, the insulating particles 210 can be efficiently attached to the conductive particles 1.
- the insulating particles 210 can be uniformly attached to the surface of the conductive particles 1 without any defects.
- insulation reliability can be ensured even when the circuit electrode interval is narrow, but between the electrically connected electrodes. Connection resistance is low and conduction reliability is good.
- the method for attaching the insulating particles 210 having the functional group to the surface of the conductive particles 1 having the functional group via a polymer electrolyte is not particularly limited.
- Examples of a method for attaching the insulating particles 210 to the surface of the conductive particles 1 include a method in which polymer electrolytes and insulating particles 210 are alternately stacked.
- the conductive particles 1 on which the polymer electrolyte is adsorbed are dispersed in a solution containing the insulating particles 210, and the polymer electrolyte is adsorbed on at least a part of the surface of the conductive particles 1 having functional groups.
- a process of attaching and rinsing the insulating particles 210 is performed.
- the insulating coated conductive particles 100a in which the polymer electrolyte and the insulating particles 210 are laminated can be manufactured.
- the steps (1) and (2) may be in the order of (1) and (2) or in the order of (2) and (1).
- the steps (1) and (2) may be repeated alternately.
- the method of repeating the above steps (1) and (2) is called an alternating layering method (Layer-by-Layer assembly).
- the alternate lamination method is described in G.H. This is a method for forming an organic thin film published in 1992 by Decher et al. (Thin Solid Films, 210/211, p831 (1992)).
- the substrate is alternately immersed in an aqueous solution containing a polymer electrolyte having a positive charge (polycation) and a polymer electrolyte having a negative charge (polyanion).
- a combination of polycation and polyanion adsorbed on the substrate by electrostatic attraction is laminated to obtain a composite film (alternate laminated film).
- the film grows by attracting the charge of the material formed on the substrate and the material having the opposite charge in the solution by electrostatic attraction. For this reason, when the adsorption proceeds and the charge is neutralized, no further adsorption occurs. Accordingly, when reaching a certain saturation point, the film thickness does not increase any more.
- Lvov et al. Applied an alternate lamination method to fine particles, and reported a method of laminating a polymer electrolyte having a charge opposite to the surface charge of the fine particles by using the fine particle dispersions of silica, titania and ceria. (Langmuir, Vol. 13, (1997) p6195-6203).
- insulating particles having a negative surface charge and polydiallyldimethylammonium chloride (PDDA), polyethylenimine (PEI), etc., which are polycations having the opposite charge, are alternately laminated to form insulating particles. It is possible to form a fine-particle laminated thin film in which and a polymer electrolyte are alternately laminated.
- PDDA polydiallyldimethylammonium chloride
- PEI polyethylenimine
- the solution containing an excess polymer electrolyte may be washed away by rinsing with a solvent alone. Good. Even after the conductive particles 1 on which the polymer electrolyte is adsorbed are immersed in the dispersion containing the insulating particles 210, the dispersion containing the excess insulating particles 210 may be washed away by rinsing with only the solution.
- Examples of the solution used for such rinsing include, but are not limited to, water, alcohol, acetone, and a mixed solvent thereof.
- the polymer electrolyte is capable of adsorbing with the functional group introduced on the surface of the conductive particle 1.
- This polymer electrolyte is, for example, electrostatically adsorbed to the functional group.
- a polymer electrolyte for example, a polymer (polyanion or polycation) ionized in an aqueous solution and having a charged functional group in the main chain or side chain can be used.
- the polyanion (anionic polymer) generally include those having a functional group capable of carrying a negative charge, such as sulfonic acid, sulfuric acid, and carboxylic acid.
- the polycation generally has a positively charged functional group such as polyamines such as polyethyleneamine (PEI), polyallylamine hydrochloride (PAH), polydiallyldimethyl.
- PEI polyethyleneamine
- PAH polyallylamine hydrochloride
- a copolymer containing at least one selected from the group consisting of ammonium chloride (PDDA), polyvinylpyridine (PVP), polylysine, and polyacrylamide can be used.
- Polyethyleneimine is preferably used from the viewpoint of high charge density and strong binding force to negatively charged surfaces and materials.
- This polymer electrolyte may be the same as the above-described cationic polymer used for the surface treatment of the resin particles 101.
- alkali metal Li, Na, K, Rb, Cs
- alkaline earth metal Ca, Sr, Ba, Ra
- halide ions fluorine
- Ion, chloride ion, bromine ion, iodine ion which does not substantially contain is preferable.
- the polymer electrolytes are all soluble in water-soluble organic solvents, alcohols and the like.
- the weight average molecular weight of the polymer electrolyte cannot be generally determined depending on the type of polymer electrolyte used.
- the weight average molecular weight of the polymer electrolyte may be, for example, 1,000 to 200,000, 10,000 to 200,000, or 20,000 to 100,000.
- the weight average molecular weight of the polymer electrolyte is 1,000 to 200,000, sufficient dispersibility of the insulating coated conductive particles 100a can be obtained. Even if the average particle diameter of the insulating coated conductive particles 100a is 3 ⁇ m or less, aggregation of the insulating coated conductive particles 100a can be prevented.
- the solution containing the polymer electrolyte is obtained by dissolving the polymer electrolyte in a mixed solvent of water and an organic solvent.
- water-soluble organic solvents examples include methanol, ethanol, propanol, acetone, dimethylformamide, and acetonitrile.
- the concentration of the polymer electrolyte in the solution may be, for example, 0.01% by mass to 10% by mass, 0.03% by mass to 3% by mass, or 0.1% by mass to 1% by mass.
- concentration of the polymer electrolyte in the solution is 0.01% by mass to 10% by mass, the adhesion of the insulating particles 210 to the conductive particles 1 can be improved.
- the pH of the polymer electrolyte solution is not particularly limited.
- the coverage of the conductive particles 1 with the insulating particles 210 can be controlled by adjusting the type, weight average molecular weight, or concentration of the polymer electrolyte.
- the coverage by the insulating particles 210 tends to be high.
- a polymer electrolyte having a low charge density such as PDDA the coverage by the insulating particles 210 tends to be low.
- the weight average molecular weight of the polymer electrolyte is large, the coverage with the insulating particles 210 tends to increase.
- the weight average molecular weight of the polymer electrolyte is small, the coverage with the insulating particles 210 tends to be low.
- the concentration of the polymer electrolyte in the solution is increased, the coverage with the insulating particles 210 tends to increase.
- the concentration of the polymer electrolyte in the solution is low, the coverage with the insulating particles 210 tends to be low.
- the type, weight average molecular weight and concentration of the polymer electrolyte can be appropriately selected.
- the surface of the conductive particles 1 has, for example, a polymer having a weight average molecular weight of 1,000 or more, the dispersion of the conductive particles 1 is promoted. For this reason, even when the magnetic aggregation increases as the particle size of the conductive particles 1 decreases, the aggregation of the conductive particles 1 can be suppressed, and the adhesion of the insulating particles 210 to the conductive particles 1 can be facilitated.
- a polymer or oligomer having a weight average molecular weight of 500 to 10,000 may exist on the surface of the insulating particle 210.
- the polymer or oligomer may have a weight average molecular weight of 1,000 to 4,000.
- Such a polymer or oligomer is preferably a silicone oligomer having a functional group having a weight average molecular weight of 1,000 to 4,000.
- the functional group is preferably one that reacts with the polymer electrolyte. Examples of the functional group include a glycidyl group, a carboxyl group, and an isocyanate group, and among them, a glycidyl group is preferable.
- the dispersibility of the insulating particles 210 is further improved, and at the same time, the functional groups on the polymer or oligomer and the functional groups on the conductive particles 1 are reacted to make the conductive particles 1 and the insulating particles 210 stronger. Can be expected.
- the second insulating particles 210b made of silica tend to fall off the conductive particles 1 more easily. Even when a polymer or oligomer having a glycidyl group, a carboxyl group, or an isocyanate group is used, if the second insulating particles 210b are likely to fall off, a method of coating the surface of the second insulating particles 210b with a hydrophobizing agent can be employed. . As the surface of the second insulating particle 210b becomes hydrophobic, the surface potential (zeta potential) of the second insulating particle 210b made of silica increases toward the negative side. For this reason, since the potential difference between the second insulating particles 210b and the conductive particles 1 treated with the polymer electrolyte is increased, the second insulating particles 210b are firmly attached to the conductive particles 1 by electrostatic force.
- the hydrophobizing agent may contain at least one selected from the group consisting of the above (1) to (4).
- silazane-based hydrophobic treatment agent examples include organic silazane-based hydrophobic treatment agents.
- examples of the organic silazane hydrophobizing agent include hexamethyldisilazane, trimethyldisilazane, tetramethyldisilazane, hexamethylcyclotrisilazane, heptamethyldisilazane, diphenyltetramethyldisilazane, divinyltetramethyldisilazane, and the like.
- the organic silazane-based hydrophobizing agent may be other than the above.
- siloxane-based hydrophobizing agent As siloxane-based hydrophobizing agents, polydimethylsiloxane, methylhydrogendisiloxane, dimethyldisiloxane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3 -Diphenyltetramethyldisiloxane, methylhydrogenpolysiloxane, dimethylpolysiloxane, amino-modified siloxane and the like.
- the siloxane-based hydrophobizing agent may be other than the above.
- silane-based hydrophobizing agent As silane-based hydrophobizing agents, N, N-dimethylaminotrimethylsilane, trimethylmethoxysilane, trimethylethoxysilane, trimethylpropoxysilane, phenyldimethylmethoxysilane, chloropropyldimethylmethoxysilane, Dimethyldimethoxysilane, methyltrimethoxysilane, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, ethyltrimethoxysilane, dimethyldiethoxysilane, propyltriethoxysilane, n-butyltrimethoxysilane, n-hexyl Trimethoxysilane, n-octyltriethoxysilane, n-octylmethyldiethoxysilane, n-octa
- Titanate-based hydrophobizing agents include KRTTS, KR46B, KR55, KR41B, KR38S, KR138S, KR238S, 338X, KR44, and KR9SA (all manufactured by Ajinomoto Fine Techno Co., Ltd., trade names) ) And the like.
- the hydrophobizing agent may contain at least one selected from the group consisting of hexamethylene disilazane, polydimethylsiloxane, and N, N-dimethylaminotrimethylsilane.
- the zeta potential of the second insulating particle 210b increases toward the minus side as the surface of the second insulating particle 210b becomes hydrophobic. For this reason, the potential difference between the second insulating particles 210b and the conductive particles 1 treated with the polymer electrolyte is increased. Therefore, the conductive particles 1 and the second insulating particles 210b are firmly bonded by electrostatic force.
- the surface of the second insulating particle 210b can be coated with the hydrophobizing agent in a liquid phase such as water, an organic solvent, a mixed solution containing water and an organic solvent, or in a gas phase.
- a liquid phase such as water, an organic solvent, a mixed solution containing water and an organic solvent, or in a gas phase.
- water-soluble organic solvents examples include methanol, ethanol, propanol, acetone, dimethylformamide, and acetonitrile.
- silica pretreated with a hydrophobizing agent may be used as the second insulating particles 210b.
- the degree of hydrophobicity of the second insulating particles 210b coated with the hydrophobizing agent by the methanol titration method may be, for example, 30% or more, 50% or more, or 60% or more.
- Methanol titration method is a method for measuring the degree of hydrophobicity of powder using methanol. For example, first, 0.2 g of a powder whose hydrophobicity is to be measured is suspended on a 50 ml water surface. Next, methanol is gradually added to the water while gently stirring the water. For example, methanol is dropped using a burette. Next, the amount of methanol used when the powder on the water surface is all immersed in water is measured. Then, the percentage of the methanol volume with respect to the total volume of water and methanol is calculated, and this value is calculated as the degree of hydrophobicity of the powder.
- the coverage of the first insulating particles 210 a in the insulating particles 210 is, for example, 20 to 50% with respect to the total surface area of the conductive particles 1.
- the coverage of the first insulating particles 210a is 20% or more, better insulation reliability can be obtained.
- the coverage is 50% or less, more excellent conduction reliability can be obtained.
- the coverage of the conductive particles 1 by the first insulating particles 210a and the second insulating particles 210b may be, for example, 35% or more and 80% or less, 40% or more and 80% or less with respect to the total surface area of the conductive particles 1, 50 % Or more and 80% or less, or 60% or more and 80% or less.
- the coverage is 35% or more, the insulation reliability can be improved.
- the coverage is 80% or less, the conductive particles 1 can be efficiently coated with the insulating particles 210.
- the coverage of the insulating particles 210 means the ratio of the surface area of the insulating particles 210 in a concentric circle having a diameter that is 1 ⁇ 2 of the diameter of the insulating coated conductive particles 100a on the orthographic projection surface of the insulating coated conductive particles 100a. Specifically, an image obtained by observing the insulating coated conductive particles 100a on which the insulating particles 210 are formed at a magnification of 30,000 with an SEM is analyzed, and the ratio of the insulating particles 210 to the surface of the insulating coated conductive particles 100a is calculated. To do.
- the first insulating particles 210a having an average particle size of 200 nm or more and 500 nm or less and the average particles of 30 nm or more and 130 nm or less on the surface of the conductive particles 1.
- a second insulating particle 210b having a diameter and made of silica is attached.
- the second insulating particles 210b have an average particle diameter of 30 nm or more and 130 nm or less, the connection resistance is not easily inhibited by the second insulating particles 210b. For this reason, it is possible to obtain excellent conduction reliability even when the number of particles trapped between the electrodes is small in the connection of a minute circuit with a small electrode pad area.
- the glass transition temperature of the first insulating particles 210a may be 100 ° C. or higher and 200 ° C. or lower. Accordingly, the first insulating particles 210a are not completely melted depending on the temperature at which the anisotropic conductive adhesive containing the insulating coated conductive particles 100a is heated and pressurized. For this reason, the 1st insulating particle 210a can fully function as an insulating spacer.
- the coverage of the conductive particles 1 by the first insulating particles 210a and the second insulating particles 210b may be 35 to 80% with respect to the total surface area of the conductive particles 1.
- the insulation coating electroconductive particle 100a which is excellent by conduction
- the insulation reliability tends to be high and the conduction reliability tends to be poor.
- the coverage of insulating particles is low, the conduction reliability is high and the insulation is high. Reliability tends to deteriorate.
- first insulating particles 210a and the second insulating particles 210b having different average particle sizes are used as in the first embodiment, good conduction reliability is maintained even when the coverage is increased, and excellent insulation is achieved. Insulating coated conductive particles 100a having both reliability and conduction reliability can be obtained.
- the conductive particle 1 has a protrusion 109 on its surface.
- the second insulating particles 210b are attached to the conductive particles having a smooth surface, even if the average particle size of the second insulating particles 210b is 30 nm to 130 nm, the function of the second insulating particles 210b as an insulating spacer is high.
- the conduction reliability tends to decrease. For this reason, the conductive particle 1 having the protrusion 109 can suppress a decrease in conduction reliability.
- the surface of the second insulating particle 210b may be coated with a hydrophobizing agent.
- the surface of the conductive particles 1 may be coated with a polymer electrolyte (cationic polymer).
- the second insulating particles 210b coated with the hydrophobizing agent are more likely to be negatively charged than the second insulating particles 210b that are not hydrophobized, and are firmly attached to the conductive particles 1 by static electricity. . For this reason, it is possible to obtain insulating coated conductive particles having a high function as an insulating spacer and excellent in insulation reliability.
- the surface of the second insulating particle 210b may be selected from the group consisting of a silazane hydrophobic treatment agent, a siloxane hydrophobic treatment agent, a silane hydrophobic treatment agent, and a titanate hydrophobic treatment agent.
- the hydrophobizing agent may be selected from the group consisting of hexamethylene disilazane (HMDS), polydimethylsiloxane (PDMS), and N, N-dimethylaminotrimethylsilane (DMATMS).
- HMDS hexamethylene disilazane
- PDMS polydimethylsiloxane
- DMATMS N, N-dimethylaminotrimethylsilane
- the degree of hydrophobicity of the second insulating particles 210b by the methanol titration method may be 30% or more.
- the conductive particles 1 may include resin particles 101 and a metal layer covering the resin particles 101, and the metal layer may include a first layer 104 containing nickel.
- the anisotropic conductive adhesive can achieve both excellent conduction reliability and insulation reliability.
- only one layer of the insulating particles 210 may be coated.
- the bond between the insulating particles 210 and the conductive particles 1 may be further strengthened by heating and drying the insulating coated conductive particles 100a.
- the reason why the bonding force increases is, for example, the strengthening of the chemical bond between a functional group such as a carboxyl group introduced on the surface of the conductive particle 1 and a functional group such as a hydroxyl group introduced on the surface of the insulating particle 210. .
- the temperature for heat drying is set to 60 to 100 ° C., for example. When the temperature is 60 ° C. or higher, the insulating particles 210 are difficult to peel off from the conductive particles 1, and when the temperature is 100 ° C. or lower, the conductive particles 1 are difficult to deform.
- the time for heat drying is set to, for example, 10 minutes to 180 minutes. When the heat drying time is 10 minutes or longer, the insulating particles 210 are difficult to peel off, and when it is 180 minutes or shorter, the conductive particles 1 are difficult to deform.
- the insulating coated conductive particles 100a may be surface-treated with a silicone oligomer, octadecylamine or the like. Thereby, the insulation reliability of the insulation coating conductive particle 100a can be improved. Furthermore, the insulation reliability of the insulating coated conductive particles 100a can be further improved by using a condensing agent as necessary.
- FIG. 2 is a schematic cross-sectional view showing the insulating coated conductive particles according to the second embodiment.
- the insulating coated conductive particles 100b shown in FIG. 2 have the same configuration as the insulating coated conductive particles 100a shown in FIG. 1, except that the second layer 105 provided on the first layer 104 is provided. That is, the metal layer covering the resin particles 101 and the nonconductive inorganic particles 102 of the insulating coated conductive particles 100 b includes the first layer 104 and the second layer 105.
- the second layer 105 may be a metal layer or an alloy layer.
- the second layer 105 is a conductive layer provided so as to cover the first layer 104.
- the thickness of the second layer 105 is, for example, 5 nm to 100 nm.
- the thickness of the second layer 105 may be 5 nm or more, or 10 nm or more.
- the thickness of the second layer 105 may be 30 nm or less.
- the thickness of the second layer 105 can be made uniform when the second layer 105 is formed. For example, nickel) can be satisfactorily prevented from diffusing to the surface opposite to the second layer 105.
- the thickness of the second layer 105 is calculated using a photograph taken by a TEM.
- a cross section of the insulating coated conductive particle 100b is cut out by an ultramicrotome method so as to pass through the vicinity of the center of the insulating coated conductive particle 100b.
- the cut section is observed at a magnification of 250,000 times using a TEM to obtain an image.
- the thickness of the second layer 105 can be calculated from the cross-sectional area of the second layer 105 estimated from the obtained image.
- component analysis is performed by component analysis using EDX attached to the TEM.
- the second layer 105 is an average value of the thickness of 10 conductive particles.
- the second layer 105 contains at least one selected from the group consisting of noble metals and cobalt.
- the noble metal is palladium, rhodium, iridium, ruthenium, platinum, silver, or gold.
- money the conduction
- the second layer 105 functions as an antioxidant layer for the first layer 104 containing nickel. Therefore, the second layer 105 is formed on the first layer 104.
- the thickness of the second layer 105 in the case of containing gold may be 30 nm or less. In this case, the balance between the reduction effect of the conduction resistance on the surface of the insulating coated conductive particles 100b and the manufacturing cost is excellent. However, the thickness of the second layer 105 in the case of containing gold may exceed 30 nm.
- the second layer 105 is preferably composed of at least one selected from the group consisting of palladium, rhodium, iridium, ruthenium and platinum. In this case, the oxidation of the surface of the insulating coated conductive particles 100b can be suppressed, and the insulation reliability of the insulating coated conductive particles 100b can be improved.
- the second layer 105 is more preferably composed of at least one selected from the group consisting of palladium, rhodium, iridium, and ruthenium.
- the first layer 104 that becomes the protrusions 109 formed on the nonconductive inorganic particles 102 is suppressed from being crushed, and the compressed insulating coated conductive The increase in resistance of the particles 100b is suppressed.
- the second layer 105 is formed on the composite particles 103 covered with the first layer 104 by, for example, electroless plating after forming the first layer 104 in the fourth step of the first embodiment. .
- the second layer 105 can be formed by, for example, electroless palladium plating.
- Electroless palladium plating may use either a substitution type that does not use a reducing agent or a reduction type that uses a reducing agent.
- MCA trade name, manufactured by World Metal Co., Ltd.
- the reduction type include APP (trade name, manufactured by Ishihara Chemical Co., Ltd.) and the like.
- the lower limit of the palladium content in the second layer 105 may be 90% by mass or more, 93% by mass or more, and 94% by mass based on the total amount of the second layer 105. % Or more.
- the upper limit of the palladium content in the second layer 105 may be 99% by mass or less or 98% by mass or less based on the total amount of the second layer 105.
- the reducing agent used in the electroless palladium plating solution is not particularly limited. Phosphorus-containing compounds such as acids, phosphorous acid, and alkali salts thereof; boron-containing compounds and the like can be used. In that case, the resulting second layer 105 includes a palladium-phosphorus alloy or a palladium-boron alloy. For this reason, it is preferable to adjust the concentration of the reducing agent, the pH, the temperature of the plating solution, and the like so that the palladium content in the second layer 105 falls within a desired range.
- the second layer 105 contains rhodium
- the second layer 105 can be formed by electroless rhodium plating, for example.
- the supply source of rhodium used in the electroless rhodium plating solution include ammine rhodium hydroxide, ammine rhodium nitrate, ammine rhodium acetate, ammine rhodium sulfate, ammine rhodium sulfite, ammine rhodium bromide, and an ammine rhodium compound.
- Examples of the reducing agent used in the electroless rhodium plating solution include hydrazine, sodium hypophosphite, dimethylamine borate, diethylamine borate, and sodium borohydride.
- hydrazine is preferable.
- a stabilizer or complexing agent (ammonium hydroxide, hydroxylamine salt, hydrazine dichloride, etc.) may be added to the electroless rhodium plating solution.
- the temperature (bath temperature) of the electroless rhodium plating solution may be 40 ° C. or higher, or 50 ° C. or higher from the viewpoint of obtaining a sufficient plating rate.
- the temperature of the plating solution may be 90 ° C. or lower or 80 ° C. or lower from the viewpoint of stably holding the electroless rhodium plating solution.
- the second layer 105 can be formed by, for example, electroless iridium plating.
- the source of iridium used in the electroless iridium plating solution include iridium trichloride, iridium tetrachloride, iridium tribromide, iridium tetrabromide, iridium hexachloride, tripotassium hexachloride, iridium hexachloride, iridium hexachloride Examples include sodium, disodium iridium hexachloride, tripotassium iridium hexabromide, dipotassium iridium hexabromide, tripotassium iridium hexaiodide, diiridium trissulfate, and iridium bissulfate.
- Examples of the reducing agent used in the electroless iridium plating solution include hydrazine, sodium hypophosphite, dimethylamine borate, diethylamine borate, and sodium borohydride.
- hydrazine is preferable.
- a stabilizer or complexing agent may be added to the electroless iridium plating solution.
- the stabilizer or complexing agent at least one selected from the group consisting of monocarboxylic acids, dicarboxylic acids and salts thereof may be added.
- the monocarboxylic acid include formic acid, acetic acid, propionic acid, butyric acid, lactic acid and the like.
- the dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, malic acid and the like.
- the salt include compounds in which sodium, potassium, lithium or the like is bound as a counter ion to the carboxylic acid.
- a stabilizer or a complexing agent can be used individually by 1 type or in combination of 2 or more types.
- the pH of the electroless iridium plating solution may be 1 or more, or 2 or more from the viewpoint of suppressing corrosion of the plating object and obtaining a sufficient plating rate.
- the pH of the electroless iridium plating solution may be 6 or less or 5 or less from the viewpoint that inhibition of the plating reaction is easily suppressed.
- the temperature (bath temperature) of the electroless iridium plating solution may be 40 ° C. or higher, or 50 ° C. or higher from the viewpoint of obtaining a sufficient plating rate.
- the temperature (bath temperature) of the electroless iridium plating solution may be 90 ° C. or less or 80 ° C. or less from the viewpoint of stably holding the electroless iridium plating solution.
- the second layer 105 contains ruthenium
- the second layer 105 can be formed by electroless ruthenium plating, for example.
- electroless ruthenium plating solution for example, a commercially available plating solution can be used, and electroless ruthenium Ru (trade name, manufactured by Okuno Pharmaceutical Co., Ltd.) can be used.
- the second layer 105 contains platinum
- the second layer 105 can be formed by, for example, electroless platinum plating.
- platinum used for the electroless platinum plating solution, for example, Pt (NH 3 ) 4 (NO 3 ) 2 , Pt (NH 3 ) 4 (OH) 2 , PtCl 2 (NH 3 ) 2 , Pt (NH) 3 ) 2 (OH) 2 , (NH 4 ) 2 PtCl 6 , (NH 4 ) 2 PtCl 4 , Pt (NH 3 ) 2 Cl 4 , H 2 PtCl 6 , and PtCl 2 .
- Examples of the reducing agent used in the electroless platinum plating solution include hydrazine, sodium hypophosphite, dimethylamine borate, diethylamine borate, and sodium borohydride.
- hydrazine is preferable.
- a stabilizer or complexing agent (hydroxylamine chloride, hydrazine dichloride, ammonium hydroxide, EDTA, etc.) may be added to the electroless platinum plating solution.
- the temperature (bath temperature) of the electroless platinum plating solution may be 40 ° C. or higher, or 50 ° C. or higher from the viewpoint of obtaining a sufficient plating rate.
- the temperature (bath temperature) of the electroless platinum plating solution may be 90 ° C. or less or 80 ° C. or less from the viewpoint of stably holding the electroless platinum plating solution.
- the pH of the electroless platinum plating solution may be, for example, 8-12.
- the pH is 8 or more, platinum is sufficiently easily precipitated.
- the pH is 12 or less, a good working environment can be easily secured.
- the second layer 105 can be formed by, for example, electroless silver plating.
- the silver supply source used in the electroless silver plating solution is not particularly limited as long as it is soluble in the plating solution.
- silver nitrate, silver oxide, silver sulfate, silver chloride, silver sulfite, silver carbonate, silver acetate, silver lactate, silver sulfosuccinate, silver sulfonate, silver sulfamate, and silver oxalate are used.
- a water-soluble silver compound can be used individually by 1 type or in combination of 2 or more types.
- the reducing agent used in the electroless silver plating solution is not particularly limited as long as it has the ability to reduce the water-soluble silver compound in the electroless silver plating solution to metallic silver and is a water-soluble compound.
- hydrazine derivatives, formaldehyde compounds, hydroxylamines, saccharides, Rossell salts, borohydride compounds, hypophosphites, DMAB, and ascorbic acid can be used.
- a reducing agent can be used individually by 1 type or in combination of 2 or more types.
- a stabilizer or complexing agent may be added to the electroless silver plating solution.
- the stabilizer or complexing agent for example, sulfite, succinimide, hydantoin derivative, ethylenediamine, and ethylenediaminetetraacetic acid (EDTA) can be used.
- EDTA ethylenediaminetetraacetic acid
- a stabilizer or a complexing agent can be used individually by 1 type or in combination of 2 or more types.
- additives such as known surfactants, pH adjusters, buffers, smoothing agents, stress relieving agents may be added to the electroless silver plating solution.
- the electroless silver plating solution may be in the range of 0 to 80 ° C. as the solution temperature.
- the temperature of the electroless silver plating solution is 0 ° C. or higher, the silver deposition rate is sufficiently high, and the time for obtaining a predetermined silver deposition amount can be shortened.
- the temperature of the electroless silver plating solution is 80 ° C. or lower, it is possible to suppress the loss of the reducing agent due to the self-decomposition reaction and the decrease in the stability of the electroless silver plating solution.
- the temperature is about 10 to 60 ° C., the stability of the electroless silver plating solution can be further improved.
- the pH of the electroless silver plating solution (for example, reduced electroless silver plating solution) is, for example, 1 to 14.
- the pH of the plating solution is about 6 to 13
- the stability of the plating solution can be further improved.
- an acid having an anion portion of the same kind as that of the water-soluble silver salt for example, sulfuric acid, water-soluble when silver sulfate is used as the water-soluble silver salt
- Nitric acid is used when silver nitrate is used as the silver salt.
- alkali metal hydroxide, ammonia or the like is used.
- the second layer 105 contains gold
- the second layer 105 can be formed by, for example, electroless gold plating.
- the electroless gold plating solution include a displacement type gold plating solution (for example, product name “HGS-100” manufactured by Hitachi Chemical Co., Ltd.) and a reduction type gold plating solution (for example, product name “HGS- manufactured by Hitachi Chemical Co., Ltd.). 2000 ”) or the like.
- the substitution type and the reduction type are compared, it is preferable to use the reduction type from the viewpoint that there are few voids and the covering area is easily secured.
- the second layer 105 can be formed by, for example, electroless cobalt plating.
- the cobalt supply source used in the electroless cobalt plating solution include cobalt sulfate, cobalt chloride, cobalt nitrate, cobalt acetate, and cobalt carbonate.
- Examples of the reducing agent used in the electroless cobalt plating solution include hypophosphites such as sodium hypophosphite, ammonium hypophosphite, nickel hypophosphite, and hypophosphorous acid.
- a stabilizer or a complexing agent (such as an aliphatic carboxylic acid) may be added to the electroless cobalt plating solution.
- a stabilizer or a complexing agent can be used individually by 1 type or in combination of 2 or more types.
- the temperature (bath temperature) of the electroless cobalt plating solution may be 40 ° C. or higher or 50 ° C. or higher from the viewpoint of obtaining a sufficient plating rate.
- the temperature (bath temperature) of the electroless cobalt plating solution may be 90 ° C. or less or 80 ° C. or less from the viewpoint of stably holding the electroless cobalt plating solution.
- a compound having any one of a mercapto group, a sulfide group, and a disulfide group that forms a coordinate bond with gold or palladium is used.
- One or more functional groups selected from the group consisting of a hydroxyl group, a carboxyl group, an alkoxyl group, and an alkoxycarbonyl group may be attached to the surface.
- the compound include mercaptoacetic acid, 2-mercaptoethanol, methyl mercaptoacetate, mercaptosuccinic acid, thioglycerin, or cysteine.
- the first layer 104 is the outermost layer of the insulating coated conductive particles 100a.
- the metal layer of the second embodiment has a second layer 105 provided on the first layer 104, and the second layer 105 contains a metal selected from the group consisting of noble metals and cobalt.
- the outermost layer of the insulating coated conductive particles 100 b becomes the second layer 105. Since the second layer 105 has a function of preventing elution of nickel from the first layer 104, the occurrence of nickel migration can be suppressed. In addition, since the second layer 105 is relatively difficult to oxidize, the conductive performance of the insulating coated conductive particles 100b is unlikely to deteriorate. Since the insulating coated conductive particles 100b include the second layer 105, the number, size, and shape of the protrusions 109 can be highly controlled.
- FIG. 3 is a schematic cross-sectional view showing insulating coated conductive particles according to the third embodiment.
- 3 is a first layer that is a resin layer 101, palladium particles 106 containing palladium, nickel particles 107 containing nickel, and a metal layer provided on the surface of the resin particles 101. 108.
- the palladium particles 106 are disposed closer to the resin particles 101 than the nickel particles 107 and are covered with the nickel particles 107.
- Projections 109 reflecting the shapes of the palladium particles 106 and the nickel particles 107 are formed on the outer surface of the first layer 108.
- the first layer 108 includes a first covering layer 108a and a second covering layer 108b. From the above, it can be seen that the insulating coated conductive particles 100c do not have the non-conductive inorganic particles 102, unlike the insulating coated conductive particles 100a of the first embodiment.
- the plurality of palladium particles 106 are disposed away from each other, for example, along the surface of the first covering layer 108a of the first layer 108 (along the direction perpendicular to the radial direction of the conductive particles 1). For example, the plurality of palladium particles 106 are scattered in a direction perpendicular to the radial direction of the conductive particles (the thickness direction of the first layer 108). Therefore, one palladium particle 106 is arranged independently without contacting another palladium particle 106 adjacent to the one palladium particle 106. Each of the plurality of palladium particles 106 has a side surface extending from the top to the bottom.
- the plurality of palladium particles 106 are, for example, electroless palladium plating deposition nuclei (reduction deposits of electroless palladium plating solution containing palladium ions and a reducing agent) formed by electroless palladium plating.
- the plurality of nickel particles 107 are arranged away from each other along the surface of the conductive particles 1. For example, the plurality of nickel particles 107 are scattered in a direction perpendicular to the radial direction of the conductive particles 1. For this reason, one nickel particle 107 is arranged independently without contacting another nickel particle 107 adjacent to the one nickel particle 107.
- the plurality of nickel particles 107 have side surfaces extending from the top to the bottom.
- the plurality of nickel particles 107 are, for example, electroless nickel plating precipitation nuclei (microprojections) formed by electroless nickel plating.
- the plurality of nickel particles 107 are formed using palladium particles 106 as nuclei. For this reason, each palladium particle 106 may be covered with a corresponding nickel particle 107.
- the first coating layer 108a may contain, for example, at least one selected from the group consisting of phosphorus and boron in addition to a metal whose main component is nickel.
- the first coating layer 108a preferably contains phosphorus.
- the first covering layer 108a When the first covering layer 108a is formed by electroless nickel plating, it may be formed in the same manner as the first layer 104 of the first embodiment.
- the first coating layer 108a containing a nickel-phosphorus alloy or a nickel-boron alloy may be formed. From the viewpoint of suppressing cracking of the first coating layer 108a, the first coating layer 108a preferably contains a nickel-phosphorus alloy.
- the nickel content in the first coating layer 108a may be, for example, 84% by mass or more, 86% by mass or more, or 88% by mass or more based on the total amount of the first coating layer 108a.
- the element content in the first coating layer 108a can be measured in the same manner as in the first layer 104 of the first embodiment.
- the thickness of the first covering layer 108a may be, for example, 20 nm or more, or 60 nm or more.
- the thickness of the first coating layer 108a may be, for example, 200 nm or less, 150 nm or less, or 100 nm or less. When the thickness of the first coating layer 108a is within the above range, the cracking of the first coating layer 108a can be easily suppressed.
- the second coating layer 108b preferably contains nickel. As shown in FIG. 3, the second covering layer 108 b constitutes the outermost layer of the protrusion 109. Such a 2nd coating layer 108b can be formed by electroless nickel plating, for example.
- the second coating layer 108b having the protrusions 109 on the outer surface can be formed by performing electroless nickel plating on the first coating layer 108a and the nickel particles 107.
- the nickel content in the second coating layer 108b is, for example, 88% by mass or more, 90% by mass or more, 93% by mass or more, or 96% by mass or more, based on the total amount of the second coating layer 108b. Good.
- the nickel content in the second coating layer 108b may be, for example, 99% by mass or less, or 98.5% by mass or less.
- the element content in the second coating layer 108b can be measured in the same manner as the first layer 104 and the first coating layer 108a of the first embodiment.
- the thickness (average thickness) of the second coating layer 108b may be, for example, 5 nm or more, 10 nm or more, or 15 nm or more.
- the thickness (average thickness) of the second coating layer 108b may be, for example, 150 nm or less, 120 nm or less, or 100 nm or less.
- the second coating layer 108b preferably contains at least one selected from the group consisting of phosphorus and boron in addition to the metal whose main component is nickel. Thereby, the hardness of the second coating layer 108b can be increased, and the conduction resistance when the conductive particles 1 are compressed can be easily kept low.
- the 2nd coating layer 108b may contain the metal which co-deposits with phosphorus or boron.
- the metal contained in the second coating layer 108b is, for example, cobalt, copper, zinc, iron, manganese, chromium, vanadium, molybdenum, palladium, tin, tungsten, and rhenium.
- the second coating layer 108b can increase the hardness of the second coating layer 108b by containing nickel and the above metal. Thereby, even if it is a case where the insulation coating electroconductive particle 100c is compressed, it can suppress that the protrusion 109 is crushed.
- the metal may include tungsten having a high hardness.
- the nickel content in the second coating layer 108b is, for example, 85% by mass or more based on the total amount of the coating layer 103b.
- Examples of the constituent material of the second coating layer 108b include a combination of nickel (Ni) and phosphorus (P), a combination of nickel (Ni) and boron (B), nickel (Ni), tungsten (W), and boron (B ) And a combination of nickel (Ni) and palladium (Pd).
- the second coating layer 108b When the second coating layer 108b is formed by electroless nickel plating, it may be formed in the same manner as the first coating layer 108a.
- the first coating layer 108a containing a nickel-phosphorus alloy or a nickel-boron alloy may be formed.
- the hardness of the nickel-boron alloy is higher than that of the nickel-phosphorus alloy. Therefore, even when the conductive particles 1 are highly compressed, the second coating layer 108b preferably contains a nickel-boron alloy from the viewpoint of suppressing the protrusions 109 from being crushed and obtaining a lower conduction resistance.
- the first coating layer 108a contains a nickel-phosphorus alloy and the second coating layer 108b contains a nickel-phosphorus alloy or a nickel-boron alloy. According to this combination, even when the conductive particles 1 are highly compressed, it is possible to suppress the cracking of the first layer 108 while suppressing the protrusion 109 from being crushed, and to further stabilize the low conduction resistance. Can be obtained.
- the first coating layer 108a contains a nickel-phosphorus alloy and the second coating layer 108b contains a nickel-phosphorus alloy, the suppression of the crushing of the protrusions 109 and the cracking of the first layer 108 are highly compatible. preferable.
- the nickel particles 107 contain a nickel-phosphorus alloy or a nickel-boron alloy
- the first coating layer 108a contains a nickel-phosphorus alloy
- the second coating layer 108b contains a nickel-phosphorus alloy or nickel.
- -More preferably, it contains a boron alloy.
- FIG. 4 is a schematic cross-sectional view showing insulating coated conductive particles according to the fourth embodiment.
- the insulating coated conductive particle 100d shown in FIG. 4 has the same configuration as the insulating coated conductive particle 100c of the third embodiment, except that the metal layer further includes the second layer 105 in addition to the first layer 108. have.
- the second layer 105 is the outermost layer of the insulating coated conductive particles 100d. For this reason, occurrence of nickel migration in the first layer 108 can be suppressed. In addition, the conductive performance of the insulating coated conductive particles 100d is unlikely to deteriorate. In addition, since the insulating coated conductive particles 100d have the second layer 105, the number, size, and shape of the protrusions 109 can be highly controlled.
- the anisotropic conductive adhesive according to the fifth embodiment includes the insulating coated conductive particles 100a according to the first embodiment and the adhesive in which the insulating coated conductive particles 100a are dispersed.
- the adhesive for example, a mixture of a heat-reactive resin and a curing agent is used.
- the adhesive include a mixture of an epoxy resin and a latent curing agent, and a mixture of a radical polymerizable compound and an organic peroxide.
- a paste or film adhesive is used as the adhesive.
- a thermoplastic resin such as phenoxy resin, polyester resin, polyamide resin, polyester resin, polyurethane resin, (meth) acrylic resin, polyester urethane resin is blended into the adhesive. May be.
- anisotropic conductive adhesive according to the fifth embodiment described above it is possible to obtain excellent insulation reliability as in the first embodiment, and it is also excellent in connection of minute circuits. It is possible to obtain conduction reliability.
- the insulating coated conductive particles 100b according to the second embodiment can be used instead of the insulating coated conductive particles 100a.
- the anisotropic conductive adhesive can achieve the effects of the insulating coated conductive particles 100b according to the second embodiment.
- Insulating coated conductive particles 100c may be used instead of the insulating coated conductive particles 100a.
- the anisotropic conductive adhesive can achieve the effects of the insulating coated conductive particles 100c according to the third embodiment.
- Insulating coated conductive particles 100d may be used instead of the insulating coated conductive particles 100a.
- the anisotropic conductive adhesive can achieve the effects of the insulating coated conductive particles 100d according to the third embodiment.
- connection structure according to the sixth embodiment is disposed between a first circuit member having a first circuit electrode, a second circuit member having a second circuit electrode, and the first circuit member and the second circuit member, And a connection portion in which the insulating coating conductive particles are dispersed.
- the connecting portion connects the first circuit member and the second circuit member to each other in a state where the first circuit electrode and the second circuit electrode are arranged to face each other.
- the first circuit electrode and the second circuit electrode are electrically connected to each other through the insulating coated conductive particles in a deformed state.
- FIG. 5 is a schematic cross-sectional view showing the connection structure according to the sixth embodiment.
- a connection structure 300 shown in FIG. 5 includes a first circuit member 310 and a second circuit member 320 that face each other, and a connection portion 330 that is disposed between the first circuit member 310 and the second circuit member 320.
- Examples of the connection structure 300 include portable products such as a liquid crystal display, a personal computer, a mobile phone, a smartphone, and a tablet.
- the first circuit member 310 includes a circuit board (first circuit board) 311 and a circuit electrode (first circuit electrode) 312 disposed on the main surface 311a of the circuit board 311.
- the second circuit member 320 includes a circuit board (first circuit board) 321 and circuit electrodes (second circuit electrodes) 322 arranged on the main surface 321 a of the circuit board 321.
- circuit members 310 and 320 include chip components such as an IC chip (semiconductor chip), a resistor chip, a capacitor chip, and a driver IC; a rigid-type package substrate. These circuit members are provided with circuit electrodes, and generally have many circuit electrodes. Specific examples of the other of the circuit members 310 and 320 (the circuit member to which the one circuit member is connected) include a flexible tape substrate having metal wiring, a flexible printed wiring board, and indium tin oxide (ITO). Examples thereof include a wiring substrate such as a glass substrate. For example, by using a film-like anisotropic conductive adhesive, these circuit members can be connected efficiently and with high connection reliability. For example, the anisotropic conductive adhesive according to the fifth embodiment is suitable for COG mounting or COF mounting on a wiring board of a chip component having many fine circuit electrodes.
- ITO indium tin oxide
- the connection part 330 includes a cured product 332 of an adhesive and insulating coated conductive particles 100a dispersed in the cured product 332.
- the film-shaped anisotropic conductive material described in the fifth embodiment is used. Adhesive is used.
- the circuit electrode 312 and the circuit electrode 322 facing each other are electrically connected via the conductive particles 1 of the insulating coated conductive particles 100a. More specifically, as shown in FIG. 6, the insulating coated conductive particles 100 a are deformed by compression and are electrically connected to both the circuit electrodes 312 and 322.
- the insulating coated conductive particles 100a maintain the insulation between the insulating coated conductive particles 100a by interposing the insulating particles 210 between the conductive particles 1 in a direction crossing the compressing direction. Therefore, the insulation reliability at a narrow pitch (for example, a pitch of 10 ⁇ m level) can be further improved.
- a first circuit member 310 having a circuit electrode 312 and a second circuit member 320 having a circuit electrode 322 are arranged such that the circuit electrode 312 and the circuit electrode 322 face each other, and It is obtained by interposing an anisotropic conductive adhesive between the circuit member 310 and the second circuit member 320, and heating and pressurizing them to electrically connect the circuit electrode 312 and the circuit electrode 322.
- the first circuit member 310 and the second circuit member 320 are bonded together by a cured product 332 of an adhesive.
- FIG. 6 is a schematic cross-sectional view for explaining an example of the manufacturing method of the connection structure shown in FIG.
- the anisotropic conductive adhesive is thermoset to produce a connection structure.
- a first circuit member 310 and an anisotropic conductive adhesive 330a are prepared.
- an adhesive film (anisotropic conductive adhesive film) formed into a film shape is used as the anisotropic conductive adhesive 330a.
- the anisotropic conductive adhesive 330a contains the insulating coated conductive particles 100a and the insulating adhesive 332a.
- the anisotropic conductive adhesive 330a is placed on the main surface 311a of the first circuit member 310 (the surface on which the circuit electrode 312 is formed). Then, as shown in FIG. 6A, the anisotropic conductive adhesive 330 a is pressurized along the direction A and the direction B. Thereby, as shown in FIG. 6B, the anisotropic conductive adhesive 330 a is laminated on the first circuit member 310.
- the second circuit member 320 is placed on the anisotropic conductive adhesive 330a so that the circuit electrode 312 and the circuit electrode 322 face each other. And the whole (the 1st circuit member 310 and the 2nd circuit member 320) is pressurized along the direction A and the direction B shown by FIG.6 (c), heating the anisotropic conductive adhesive 330a.
- the anisotropic conductive adhesive 330a is cured by heating to form the connection portion 330, and a connection structure 300 as shown in FIG. 5 is obtained.
- the anisotropic conductive adhesive may be in the form of a paste.
- the insulating coating conductive particles 100 a according to the third embodiment are included in the connection portion 330.
- the circuit electrode 312 and the circuit electrode 322 are electrically connected satisfactorily through the insulating coated conductive particles 100a. Therefore, even when the area of the circuit electrode 312 and the circuit electrode 322 is small and the number of the insulating coating conductive particles 100a captured between the circuit electrodes 312 and 322 is small, excellent conduction reliability over a long period of time. Sex is demonstrated.
- the insulating coated conductive particles 100a include the insulating particles 210, the first layers 104 (see FIG.
- connection structure 300 1) of the insulating coated conductive particles 100a in the connection portion 330 are less likely to contact each other. For this reason, for example, even when the pitch between the electrodes provided in the circuit electrode 312 (in the circuit electrode 322) is, for example, 10 ⁇ m or less, the insulating coated conductive particles 100a in the connection portion 330 are difficult to conduct. Thus, the insulation reliability of the connection structure 300 is also preferably improved.
- the insulating coated conductive particles 100a to 100d have the protrusions 109, but the insulating coated conductive particles 100a to 100d may not have the protrusions 109.
- the second insulating particles 210b in the insulating particles 210 may not be subjected to a hydrophobic treatment.
- Step a Coating of resin particle surface with cationic polymer 6 g of crosslinked polystyrene particles having an average particle size of 3.0 ⁇ m (trade name “Soliostar”, manufactured by Nippon Shokubai Co., Ltd.) are averaged in molecular weight of 70,000 (MW 7) 10 g of 30% by weight polyethyleneimine aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.) was added to an aqueous solution in 300 ml of pure water, and the mixture was stirred at room temperature for 15 minutes.
- the resin particles were taken out by filtration using a ⁇ 3 ⁇ m membrane filter (manufactured by Merck Millipore).
- the resin particles on the membrane filter were washed twice with 600 g of ultrapure water to remove non-adsorbed polyethyleneimine to obtain resin particles adsorbed with polyethyleneimine.
- Step b Coating of non-conductive inorganic particles with a hydrophobizing agent
- the vapor-phase hydrophilic spherical silica powder having an average particle size of 60 nm was used as non-conductive inorganic particles.
- 100 g of this spherical silica powder was placed in a vibrating fluidized bed apparatus (manufactured by Chuo Kako Co., Ltd., trade name “vibrating fluidized bed apparatus VUA-15 type”). Next, 1.5 g of water was sprayed and mixed for 5 minutes while fluidizing the spherical silica with air circulated by a suction blower.
- HMDS hexamethylene disilazane
- TSL-8802 Momentive Performance Materials Japan GK
- Step d Palladium catalyst application step 6.15 g of particle A was adjusted to pH 1.0 and added to 300 mL of palladium-catalyzed solution containing 20% by mass of palladium catalyst (trade name “HS201” manufactured by Hitachi Chemical Co., Ltd.). . Then, it stirred for 30 minutes at 30 degreeC, irradiating the ultrasonic wave of resonance frequency 28kHz and output 100W. Next, after filtering through a 3 ⁇ m membrane filter (manufactured by Merck Millipore), the palladium catalyst was adsorbed on the surface of the particles A by washing with water.
- FIG. 7 and FIG. 8 show the results of observing the surface of the resin particles adsorbed with the spherical silica powder by SEM (trade name “S-4800”, manufactured by Hitachi High-Technologies Corporation).
- Step e Formation of first layer After the particle B dispersion obtained in step d was diluted with 3000 mL of water heated to 80 ° C, 3 mL of a 1 g / L bismuth nitrate aqueous solution was added as a plating stabilizer. Next, an electroless nickel plating solution for forming a first layer having the following composition (an aqueous solution containing the following components. 1 g / L bismuth nitrate aqueous solution is added in an amount of 1 mL per 1 L of the plating solution, the same applies hereinafter) to the particle B dispersion. 240 mL was added dropwise at a dropping rate of 15 mL / min.
- the composition of the electroless nickel plating solution for forming the first layer is as follows. Nickel sulfate ... 400g / L Sodium hypophosphite ... 150g / L Sodium citrate ... 120g / L Bismuth nitrate aqueous solution (1 g / L) ... 1 mL / L
- Step f Formation of second layer 12.15 g of particles C obtained in step e were washed with water and filtered, and then dispersed in 3000 mL of water heated to 70 ° C. To this dispersion, 3 mL of a 1 g / L bismuth nitrate aqueous solution was added as a plating stabilizer. Next, 60 mL of an electroless nickel plating solution for forming a second layer having the following composition was dropped at a dropping rate of 15 mL / min. After 10 minutes had elapsed after the completion of the dropping, the dispersion with the plating solution added was filtered. The filtrate was washed with water and then dried with a vacuum dryer at 80 ° C.
- particles D having a second layer (corresponding to the second coating layer in the above embodiment) made of a nickel-phosphorus alloy film with a thickness of 20 nm shown in Table 1-1 were formed.
- the particle D obtained by forming the second layer was 13.65 g.
- the composition of the electroless nickel plating solution for forming the second layer is as follows. Nickel sulfate ... 400g / L Sodium hypophosphite ... 150g / L Sodium tartrate dihydrate ... 60g / L Bismuth nitrate aqueous solution (1 g / L) ... 1 mL / L
- Conductive particles were obtained by the above steps a to f.
- a cross section was cut out by an ultramicrotome method so as to pass through the vicinity of the center of the obtained conductive particles. This cross section was observed at a magnification of 250,000 times using TEM (trade name “JEM-2100F” manufactured by JEOL Ltd.). From the obtained images, the cross-sectional areas of the first layer, the second layer, and the third layer were estimated, and the film thicknesses of the first layer, the second layer, and the third layer were calculated from the cross-sectional areas. In Examples 1 to 16, 19 and Comparative Examples 1 to 5, since the third layer is not formed, only the thicknesses of the first layer and the second layer are measured for these Examples and Comparative Examples. It was targeted.
- the cross-sectional area of each layer in the cross section with a width of 500 nm was read by image analysis, and the height when converted into a rectangle with a width of 500 nm was calculated as the film thickness of each layer.
- Table 1-1 shows the average values of the film thicknesses calculated for 10 conductive particles.
- the element content (purity) in the first layer, the second layer, and the third layer was calculated. Details of a method for producing a sample in the form of a thin film (cross-sectional sample of conductive particles), details of a mapping method by EDX, and details of a method for calculating the content of elements in each layer will be described later.
- FIG. 10 is a portion within the same circle having a diameter that is half the diameter of particle D.
- a cross-sectional sample having a thickness of 60 nm ⁇ 20 nm for conducting TEM analysis and STEM / EDX analysis from the cross section of the conductive particles (hereinafter referred to as “thin film section for TEM measurement”) is prepared as follows using an ultramicrotome method. did.
- Conductive particles were dispersed in the casting resin for stable thinning. Specifically, 10 g of a mixture of bisphenol A liquid epoxy resin, butyl glycidyl ether, and other epoxy resin (Refinetech Co., Ltd., trade name “Epomount Main Agent 27-771”) is mixed with diethylenetriamine (Refinetech Corporation). (Product name “Epomount Curing Agent 27-772”) 1.0 g was mixed. It stirred using the spatula and it confirmed visually that it mixed uniformly. After adding 0.5 g of dried conductive particles to 3 g of this mixture, the mixture was stirred with a spatula until uniform.
- the mixture containing the conductive particles was poured into a mold for resin casting (DSK, manufactured by Dosaka EM Co., Ltd., trade name “silicone embedding plate type II”), and allowed to stand at room temperature (room temperature) for 24 hours. . After confirming that the casting resin was hardened, a resin casting of conductive particles was obtained.
- DSK manufactured by Dosaka EM Co., Ltd., trade name “silicone embedding plate type II”
- a thin film slice for TEM measurement was prepared from a resin cast containing conductive particles.
- EM-UC6 manufactured by Leica Microsystems Co., Ltd.
- a thin film slice for TEM measurement can be cut out using a glass knife fixed to the main body of the ultramicrotome as shown in FIG. The tip of the resin casting was trimmed until it became a shape.
- trimming was performed so that the cross-sectional shape of the tip of the resin casting was a substantially rectangular parallelepiped having a length of 200 to 400 ⁇ m and a width of 100 to 200 ⁇ m. .
- the reason why the horizontal length of the cross section is set to 100 to 200 ⁇ m is to reduce friction generated between the diamond knife and the sample when a thin film section for TEM measurement is cut out from a resin casting. This makes it easy to prevent wrinkling and bending of the thin film slice for TEM measurement, and facilitates production of the thin film slice for TEM measurement.
- a diamond knife with a boat manufactured by DIATONE, trade name “Cryo Wet”, blade width 2.0 mm, blade angle 35 °
- DIATONE trade name “Cryo Wet”
- blade width 2.0 mm blade angle 35 °
- blade angle 35 ° blade angle
- the adjustment of the knife installation angle will be described with reference to FIG.
- the vertical angle, the horizontal angle, and the clearance angle can be adjusted.
- “Adjusting the angle in the vertical direction” means adjusting the vertical angle of the sample holder so that the sample surface and the direction in which the knife advances are parallel to each other, as shown in FIG.
- “Adjusting the angle in the left-right direction” means adjusting the angle in the left-right direction of the knife so that the blade edge of the knife and the sample surface are parallel, as shown in FIG.
- “Adjustment of clearance angle” means adjusting the minimum angle formed by the sample side surface of the knife edge and the direction in which the knife advances, as shown in FIG.
- the clearance angle is preferably 5 to 10 °.
- the distance between the sample and the diamond knife is made closer, the blade speed is 0.3 mm / second, and the thinning thickness of the thin film is 60 nm ⁇ 20 nm.
- the blade speed is 0.3 mm / second, and the thinning thickness of the thin film is 60 nm ⁇ 20 nm.
- a thin film slice for TEM measurement was floated on the surface of the ion exchange water.
- a copper mesh for TEM measurement (copper mesh with a microgrid) was pressed from the upper surface of the thin film slice for TEM measurement floated on the water surface, and the thin film slice for TEM measurement was adsorbed to the copper mesh to obtain a TEM sample. Since the thin film slice for TEM measurement obtained by the microtome does not exactly match the set value of the cut-out thickness of the microtome, a set value for obtaining a desired thickness is obtained in advance.
- mapping method using EDX Details of the mapping method by EDX will be described.
- the thin film slice for TEM measurement was fixed together with a copper mesh to a sample holder (trade name “Beryllium sample biaxial tilt holder, EM-31640” manufactured by JEOL Ltd.) and inserted into the TEM.
- a sample holder trade name “Beryllium sample biaxial tilt holder, EM-31640” manufactured by JEOL Ltd.
- the electron beam irradiation system was switched to the STEM mode.
- JEOL Simple Image Viewer (Version 1.3.5)” (manufactured by JEOL Ltd.), and use it for TEM measurement. Thin film sections were observed. A portion suitable for EDX measurement was searched for and photographed in the cross section of the conductive particles observed therein.
- location suitable for measurement means a location where the cross section of the metal layer can be observed by cutting near the center of the conductive particles. The part where the cross section is inclined and the part cut at a position shifted from the vicinity of the center of the conductive particles were excluded from the measurement target.
- the observation magnification was 250,000 times, and the number of pixels of the STEM observation image was 512 points vertically and 512 points horizontally. Observation under this condition gives an observation image with a viewing angle of 600 nm. However, care should be taken because the viewing angle may change even at the same magnification when the apparatus is changed.
- the resin particles of the conductive particles and the casting resin are contracted and thermally expanded, and the sample is deformed or moved during the measurement. End up.
- the measurement site was irradiated with an electron beam for about 30 minutes to 1 hour in advance, and analysis was performed after confirming that the deformation and movement had subsided.
- EDX In order to perform STEM / EDX analysis, EDX was moved to the measurement position, and EDX measurement software “Analysis Station” (manufactured by JEOL Ltd.) was started.
- a focusing diaphragm device for focusing an electron beam at a target location is used.
- the electron beam spot diameter is in the range of 0.5 to 1.0 nm so that the number of detected characteristic X-rays (CPS: Counts Per Second) is 10,000 CPS or more. Adjusted. After the measurement, in the EDX spectrum obtained simultaneously with the mapping measurement, it was confirmed that the peak height derived from the K ⁇ ray of nickel was at least 5,000 Counts or more. At the time of data acquisition, the number of pixels was 256 points in the vertical direction and 256 points in the horizontal direction with the same viewing angle as that in the STEM observation. The integration time for each point was 20 milliseconds, and the measurement was performed once.
- CPS Counts Per Second
- EDX spectra in the first layer, the second layer, and the third layer were extracted as necessary, and the element abundance ratio in each part was calculated.
- the EDX spectrum is extracted from only the film thicknesses of the first layer and the second layer, and the presence of elements in each part The ratio was calculated.
- nickel EDX spectra of palladium plating precipitation nuclei and electroless nickel plating precipitation nuclei were extracted, and element abundance ratios in each part were calculated.
- the sum of the proportions of the noble metal, nickel and phosphorus was 100% by mass, and the mass% concentration of each element was calculated.
- the elements other than the above were excluded when calculating the quantitative values because the ratios were likely to fluctuate for the following reasons.
- the ratio of carbon increases or decreases depending on the influence of impurities adsorbed on the surface of the sample when the carbon support film used in the mesh for TEM measurement or electron beam irradiation.
- the proportion of oxygen may be increased by air oxidation between the preparation of the TEM sample and the measurement. Copper will be detected from the copper mesh used for TEM measurement.
- Step g [Preparation of first insulating particles] Insulating particle Nos. Shown in Table 6 in 400 g of pure water in a 500 ml flask. Monomers were added according to a blending molar ratio of 1. It mix
- KBM-503 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) is 3-methacryloxypropyltrimethoxysilane.
- the average particle size of the synthesized insulating particles was measured by analyzing an image taken by SEM. The results are shown in Table 6.
- the Tg (glass transition temperature) of the synthesized insulating particles was measured using DSC (manufactured by Perkin Elmer, trade name “DSC-7”): sample amount: 10 mg, heating rate: 5 ° C./min, measurement atmosphere: air It measured on condition of this.
- the weight average molecular weight of the silicone oligomer was measured by a gel permeation chromatography (GPC) method and calculated by conversion using a standard polystyrene calibration curve.
- GPC gel permeation chromatography
- a pump manufactured by Hitachi, Ltd., trade name “L-6000”
- a column Gelpack GL-R420, Gelpack GL-R430, Gelpack GL-R440 (above, Hitachi Chemical)
- a detector manufactured by Hitachi, Ltd., trade name “L-3300 type RI”.
- Tetrahydrofuran (THF) was used as an eluent, the measurement temperature was 40 ° C., and the flow rate was 2.05 mL / min.
- Step h [Preparation of second insulating particles]
- vapor-phase hydrophilic spherical silica powder having an average particle size of 60 nm was used as the second insulating particles.
- 100 g of this spherical silica powder was placed in a vibrating fluidized bed apparatus (manufactured by Chuo Kako Co., Ltd., trade name “vibrating fluidized bed apparatus VUA-15 type”). Next, 1.5 g of water was sprayed and mixed for 5 minutes while fluidizing the spherical silica with air circulated by a suction blower.
- HMDS hexamethylene disilazane
- TSL-8802 Momentive Performance Materials Japan GK
- the degree of hydrophobicity of the second insulating particles was measured by the following method. First, 50 ml of ion-exchanged water and 0.2 g of a sample (second insulating particles) are placed in a beaker, and methanol is dropped from a burette while stirring with a magnetic stirrer. As the concentration of methanol in the beaker increases, the powder gradually settles, and the mass fraction of methanol in the methanol-water mixed solution at the end point when the total amount of the powder settles is determined by the degree of hydrophobicity (% ).
- the particle size of the second insulating particles is analyzed by an image obtained by observing with a SEM at a magnification of 100,000, and the area of each of the 500 particles is measured. Next, the diameter when the particles were converted into a circle was calculated as the average particle diameter of the second insulating particles. The ratio of the standard deviation of the particle diameter to the obtained average particle diameter was calculated as a percentage, and was defined as CV.
- the zeta potential of the second insulating particles was measured by the following method.
- Zetasizer ZS trade name, manufactured by Malvern Instruments
- the dispersion was diluted with methanol so that the second insulating particles were about 0.02% by mass, and the zeta potential was measured.
- Step i [Preparation of insulating coated conductive particles]
- a reaction solution was prepared by dissolving 8 mmol of mercaptoacetic acid in 200 ml of methanol.
- 10 g of conductive particles particle D in Example 1 was added to the reaction solution, and the mixture was stirred for 2 hours at room temperature with a three-one motor and a stirring blade having a diameter of 45 mm.
- 10 g of conductive particles having a carboxyl group on the surface was obtained by filtering using a membrane filter (manufactured by Merck Millipore) having a pore size of 3 ⁇ m.
- a 30% polyethyleneimine aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.) having a weight average molecular weight of 70,000 was diluted with ultrapure water to obtain a 0.3 mass% polyethyleneimine aqueous solution.
- 10 g of conductive particles having a carboxyl group on the surface were added to a 0.3% by mass polyethyleneimine aqueous solution and stirred at room temperature for 15 minutes. Thereafter, the conductive particles were filtered using a membrane filter (manufactured by Merck Millipore) having a pore size of 3 ⁇ m, and the filtered conductive particles were put in 200 g of ultrapure water and stirred at room temperature for 5 minutes.
- the conductive particles were filtered using a membrane filter (manufactured by Merck Millipore) having a pore size of 3 ⁇ m, and washed twice with 200 g of ultrapure water on the membrane filter. By performing these operations, unimsorbed polyethyleneimine was removed, and conductive particles whose surface was coated with an amino group-containing polymer were obtained.
- a membrane filter manufactured by Merck Millipore
- the first insulating particles were treated with a silicone oligomer to prepare a methanol dispersion medium of the first insulating particles having a glycidyl group-containing oligomer on the surface (methanol dispersion medium of the first insulating particles).
- a methanol dispersion medium having second insulating particles made of silica (methanol dispersion medium of second insulating particles) was prepared.
- the conductive particles whose surfaces were coated with an amino group-containing polymer were immersed in methanol, and a methanol dispersion medium of first insulating particles was dropped.
- the coverage of the 1st insulating particle was adjusted with the dripping amount of the methanol dispersion medium of the 1st insulating particle.
- the 1st insulating particle and the 2nd insulating particle were made to adhere to the electroconductive particle by dripping the methanol dispersion medium of a 2nd insulating particle.
- the coverage of the second insulating particles was adjusted by the amount of the second insulating particles dropped.
- Table 1-1 The respective coverages of the first insulating particles and the second insulating particles are summarized in Table 1-1.
- the surface of the conductive particles was hydrophobized by washing the conductive particles with the first insulating particles and the second insulating particles attached thereto after surface treatment with a condensing agent and octadecylamine. Thereafter, it was heat-dried at 80 ° C. for 1 hour to produce insulating coated conductive particles.
- the coverage ratios of the first insulating particles and the second insulating particles existing in concentric circles having a diameter half that of the insulating coated conductive particles were calculated.
- the first insulating particles, the second insulating particles, and the conductive particles are distinguished by image analysis in a concentric circle having a diameter that is 1/2 of the diameter of the insulating coated conductive particles, and the first insulating particles that exist in the concentric circles.
- the ratio of the area of the insulating particles and the second insulating particles was calculated, and the ratio was defined as the coverage of each of the first insulating particles and the second insulating particles.
- the average value for 200 insulating coated conductive particles was determined.
- FIG. 13 shows an SEM image obtained by observing the insulating coated conductive particles.
- the evaluation may be performed based on an image obtained by observing the insulating coated conductive particles with a SEM at a magnification of 50,000 times.
- FIG. 14 shows an SEM image obtained by observing the insulating coated conductive particles.
- FIG. 14 is a portion within a concentric circle having a diameter that is 1/2 the diameter of the insulating coated conductive particles.
- phenoxy resin (trade name “PKHC” manufactured by Union Carbide), acrylic rubber (40 parts by mass of butyl acrylate, 30 parts by mass of ethyl acrylate, 30 parts by mass of acrylonitrile, 3 parts by mass of glycidyl methacrylate, weight average molecular weight : 850,000) was dissolved in 300 g of a solvent in which ethyl acetate and toluene were mixed at a mass ratio of 1: 1 to obtain a solution.
- PKHC phenoxy resin manufactured by Union Carbide
- acrylic rubber 40 parts by mass of butyl acrylate, 30 parts by mass of ethyl acrylate, 30 parts by mass of acrylonitrile, 3 parts by mass of glycidyl methacrylate, weight average molecular weight : 850,000
- a liquid epoxy resin (trade name “Novacure HX-3941”, epoxy equivalent 185, manufactured by Asahi Kasei Epoxy Co., Ltd.) containing a microcapsule-type latent curing agent, and a liquid epoxy resin (Oka Shell Epoxy Corporation) (Product name “YL980”) and 400 g were added and stirred.
- An adhesive solution was prepared by adding silica slurry (trade name “R202”, manufactured by Nippon Aerosil Co., Ltd.) in which silica having an average particle diameter of 14 nm was dispersed in a solvent to the obtained mixed solution. The silica slurry was added so that the content of the silica solid content was 5% by mass with respect to the total solid content of the mixed solution.
- a dispersion medium in which ethyl acetate and toluene were mixed at a mass ratio of 1: 1 and insulating coated conductive particles were placed and ultrasonically dispersed to prepare a dispersion.
- the ultrasonic dispersion was performed by immersing the beaker in an ultrasonic bath (trade name “US107” manufactured by SND Co., Ltd.) having a frequency of 38 kHz, an energy of 400 W, and a volume of 20 L, and stirred for 1 minute.
- the dispersion was mixed with the adhesive solution to prepare a solution.
- This solution was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 40 ⁇ m) with a roll coater. And the separator with which the solution was apply
- the adhesive solution was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 40 ⁇ m) with a roll coater, and then heated and dried at 90 ° C. for 10 minutes to prepare an adhesive film B having a thickness of 3 ⁇ m.
- the adhesive solution was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 40 ⁇ m) with a roll coater, and then dried at 90 ° C. for 10 minutes to prepare an adhesive film C having a thickness of 10 ⁇ m.
- each adhesive film was laminated in the order of adhesive film B, adhesive film A, and adhesive film C to prepare an anisotropic conductive adhesive film D consisting of three layers.
- gold bump (1) area: about 30 ⁇ m ⁇ about 40 ⁇ m, height: 15 ⁇ m
- gold bump (2) area: about 40 ⁇ m ⁇ about 40 ⁇ m, high 15 mm
- a chip provided with 362 gold bumps 1.7 mm ⁇ 20 mm, thickness: 0.5 ⁇ m
- a glass substrate with an IZO circuit thickness: 0.7 mm
- a connection structure was obtained in accordance with the following procedures i) to iii).
- the space of the gold bumps (1) and (2) was 8 ⁇ m. A space corresponds to the distance between gold bumps.
- connection structure The conduction resistance test and the insulation resistance test of the obtained connection structure were performed as follows.
- connection region of about 30 ⁇ m ⁇ about 40 ⁇ m the chip electrode and the IZO circuit were set to be connected by six insulating coated conductive particles (capture insulating coated conductive particles).
- the chip electrode and the IZO circuit were set to be connected by 10 insulating coated conductive particles.
- it measured about 20 samples and computed those average values.
- Table 8-1 The results of evaluating the conduction resistance from the average value obtained according to the following criteria are shown in Table 8-1. In the case where the number of bumps was 6, and when the following criteria A was satisfied after 500 hours of the moisture absorption heat test, it was evaluated that the conduction resistance was good.
- Insulation resistance test As the insulation resistance between the chip electrodes, an initial value of the insulation resistance and a value after a migration test (temperature, 60 ° C., humidity 90%, 20 V application for 100, 300, 1000, 2000 hours) were measured.
- the adhesive film A an adhesive film having 70,000 pieces / mm 2 of insulating coating conductive particles per unit area and an adhesive coating of 100,000 pieces / mm 2 of insulating coating conductive particles per unit area.
- Two types of agent films were used. Twenty samples were measured in each film containing each insulating coating conductive particle. Of 20 samples of each film, the proportion of samples with an insulation resistance value of 10 9 ⁇ or more was calculated. The insulation resistance was evaluated from the obtained ratio according to the following criteria.
- Example 2 Instead of the first insulating particles of Example 1, conductive particles and insulating coatings were performed in the same manner as in Example 1 except that the insulating particles (insulating particles No. 2) having an average particle diameter of 239 nm shown in Table 6 were changed. Production of conductive particles, anisotropic conductive adhesive films and connection structures, and evaluation of the insulating coated conductive particles and connection structures were performed. The results are shown in Table 1-1 and Table 8-1.
- Example 3 Instead of the first insulating particles of Example 1, conductive particles and insulating coatings were performed in the same manner as in Example 1 except that the insulating particles (insulating particles No. 3) having an average particle diameter of 402 nm shown in Table 6 were changed. Production of conductive particles, anisotropic conductive adhesive films and connection structures, and evaluation of the insulating coated conductive particles and connection structures were performed. The results are shown in Table 1-1 and Table 8-1.
- Example 4 Implemented except that instead of the second insulating particles of Example 1, it was changed to insulating particles (silica particles No. 2) made of gas phase method hydrophilic spherical silica powder having an average particle size of 40 nm shown in Table 7-1.
- insulating particles silicon particles No. 2 made of gas phase method hydrophilic spherical silica powder having an average particle size of 40 nm shown in Table 7-1.
- production of conductive particles, insulating coated conductive particles, anisotropic conductive adhesive film and connection structure, and evaluation of insulating coated conductive particles and connection structure were performed. The results are shown in Table 1-1 and Table 8-1.
- Example 5 Instead of the second insulating particles of Example 1, it was carried out except that the insulating particles (silica particles No. 4) made of vapor-phase hydrophilic spherical silica powder having an average particle size of 80 nm shown in Table 7-1 were changed. In the same manner as in Example 1, production of conductive particles, insulating coated conductive particles, anisotropic conductive adhesive film and connection structure, and evaluation of insulating coated conductive particles and connection structure were performed. The results are shown in Table 1-2 and Table 8-2.
- Example 6 Example 1 except that instead of the second insulating particle of Example 1, the insulating particle (silica particle No. 5) made of gas phase method hydrophilic spherical silica powder having an average particle diameter of 100 nm shown in Table 7-1 was used. In the same manner as above, the production of conductive particles, insulating coated conductive particles, anisotropic conductive adhesive film and connection structure, and evaluation of the insulating coated conductive particles and connection structure were performed. The results are shown in Table 1-2 and Table 8-2.
- Example 7 ⁇ Example 7> Implemented except that instead of the second insulating particles of Example 1, it was changed to insulating particles (silica particle No. 6) made of gas phase method hydrophilic spherical silica powder having an average particle size of 120 nm shown in Table 7-1.
- insulating particles silicon particle No. 6
- Table 7-1 insulating particles
- production of conductive particles, insulating coated conductive particles, anisotropic conductive adhesive film and connection structure, and evaluation of insulating coated conductive particles and connection structure were performed. The results are shown in Table 1-2 and Table 8-2. 15 and 16 show SEM images observed after coating the insulating coated conductive particles.
- FIG. 16 is a portion within a concentric circle having a diameter that is half the diameter of the insulating coated conductive particles.
- Example 1 except that the coverage of the first insulating particles was changed to the range shown in Table 2-1 by changing the dropping amount of the methanol dispersion medium of the first insulating particles in (Step i) of Example 1.
- conductive particles, insulating coated conductive particles, anisotropic conductive adhesive films, and connection structures were prepared, and insulating coated conductive particles and connection structures were evaluated. The results are shown in Table 2-1, Table 8-2 and Table 8-3.
- Examples 11 to 13> In (Step i) of Example 1, the coverage of the second insulating particles was changed to the range shown in Table 2-1 and Table 2-2 by changing the dropping amount of the methanol dispersion medium of the second insulating particles. Except for this, in the same manner as in Example 1, conductive particles, insulating coated conductive particles, anisotropic conductive adhesive films and connection structures were prepared, and insulating coated conductive particles and connection structures were evaluated. The results are shown in Table 2-1, Table 2-2, and Table 9-1.
- Example 14> instead of the second insulating particles of Example 1, a colloidal silica dispersion having an average particle size of 40 nm was used. Specifically, second insulating particles (silica particle No. 8) shown in Table 7-2 whose surface was not hydrophobized were used. Except this, it carried out similarly to Example 1, and produced the electroconductive particle, the insulation coating conductive particle, the anisotropically conductive adhesive film, and the connection structure, and evaluated the insulation coating electroconductive particle and the connection structure. The results are shown in Table 2-2 and Table 9-1.
- Example 15 Instead of the second insulating particles of Example 1, a colloidal silica dispersion having an average particle diameter of 60 nm was used. Specifically, the second insulating particles (silica particles No. 9) shown in Table 7-2 whose surface was not hydrophobized were used. Except this, it carried out similarly to Example 1, and produced the electroconductive particle, the insulation coating conductive particle, the anisotropically conductive adhesive film, and the connection structure, and evaluated the insulation coating electroconductive particle and the connection structure. The results are shown in Table 3-1 and Table 9-2.
- Example 16> instead of the second insulating particles of Example 1, a colloidal silica dispersion having an average particle size of 80 nm was used. Specifically, the second insulating particles (silica particle No. 10) shown in Table 7-2 whose surface was not hydrophobized were used. Except this, it carried out similarly to Example 1, and produced the electroconductive particle, the insulation coating conductive particle, the anisotropically conductive adhesive film, and the connection structure, and evaluated the insulation coating electroconductive particle and the connection structure. The results are shown in Table 3-1 and Table 9-2.
- Example 17 Instead of the second insulating particles in Example 1 (Step h), a colloidal silica dispersion having an average particle size of 100 nm was used. Specifically, second insulating particles (silica particles No. 11) shown in Table 7-2 whose surface was not hydrophobized were used. Except this, it carried out similarly to Example 1, and produced the electroconductive particle, the insulation coating conductive particle, the anisotropically conductive adhesive film, and the connection structure, and evaluated the insulation coating electroconductive particle and the connection structure. The results are shown in Table 3-1 and Table 9-2.
- Example 18 13.3 g of particles D obtained in Example 1 (steps a to f) are immersed in 3 L of electroless palladium plating solution having the following composition to form a third layer (corresponding to the second layer in the above embodiment).
- conductive particles shown in Table 3-1 were obtained.
- the reaction time was 10 minutes and the temperature was 50 ° C.
- the average thickness of the third layer was 10 nm, and the palladium content in the third layer was 100% by mass. Except that this conductive particle was used, the insulation coated conductive particles, the anisotropic conductive adhesive film and the connection structure were produced in the same manner as in Example 1, and the insulation coated conductive particles and the connection structure were evaluated. .
- the results are shown in Table 3-1 and Table 9-2.
- composition of the electroless palladium plating solution is as follows. Palladium chloride ... 0.07g / L EDTA ⁇ 2 sodium ⁇ ⁇ ⁇ 1g / L Citric acid ⁇ disodium ⁇ ⁇ ⁇ 1g / L Sodium formate ... 0.2g / L pH ... 6
- Example 19 13.65 g of particles D were immersed in 3 mL of 100 mL / L of a displacement gold plating solution (manufactured by Hitachi Chemical Co., Ltd., trade name “HGS-100”) by (steps a to f) of Example 1 at 85 ° C. for 2 minutes. And then washed with water for 2 minutes to form a third layer. The reaction time was 10 minutes and the temperature was 60 ° C. The average thickness of the third layer was 10 nm, and the gold content in the third layer was approximately 100% by mass.
- a displacement gold plating solution manufactured by Hitachi Chemical Co., Ltd., trade name “HGS-100”
- Example 20 Conductive particles shown in Table 4 were obtained through the following steps j to n instead of 13.65 g of the particles D obtained in (Steps a to f) of Example 1. Except that this conductive particle was used, the insulation coated conductive particles, the anisotropic conductive adhesive film and the connection structure were produced in the same manner as in Example 1, and the insulation coated conductive particles and the connection structure were evaluated. . The results are shown in Table 4 and Table 9-3.
- Step j Pretreatment step 6 g of crosslinked polystyrene particles having an average particle size of 3.0 ⁇ m (trade name “Soliostar” manufactured by Nippon Shokubai Co., Ltd.) and palladium catalyst (manufactured by Atotech Japan Co., Ltd., trade name “Atotech Neo Gant 834”) ]) was added to 100 mL of a palladium-catalyzed solution containing 8% by mass and stirred at 30 ° C. for 30 minutes. Next, resin particles were taken out by filtration using a ⁇ 3 ⁇ m membrane filter (manufactured by Merck Millipore).
- the resin particles taken out were added to a 0.5 mass% dimethylamine borane liquid adjusted to pH 6.0 to obtain resin particles whose surface was activated. And after immersing the resin particle in which the surface was activated in 60 mL distilled water, the resin particle dispersion liquid was obtained by carrying out ultrasonic dispersion
- Step k Formation of first layer
- the resin particle dispersion obtained in step j was diluted with 3000 mL of water heated to 80 ° C, 3 mL of a 1 g / L bismuth nitrate aqueous solution was added as a plating stabilizer.
- 240 mL of the electroless nickel plating solution for forming the first layer used in Example 1 was added dropwise to the dispersion containing 6 g of resin particles at a dropping rate of 5 mL / min.
- the dispersion with the plating solution added was filtered.
- the filtrate was washed with water and then dried with a vacuum dryer at 80 ° C.
- a first layer made of a nickel-phosphorus alloy film having a thickness of 80 nm shown in Table 4 was formed.
- the particle E obtained by forming the first layer was 12 g.
- Step l Formation of palladium particles Particles E (12 g) forming the first layer were immersed in 1 L of electroless palladium plating solution having the following composition. Thereby, particles F in which palladium particles (palladium plating precipitation nuclei) were formed on the surfaces of the particles E were obtained. The reaction was carried out at a temperature of 60 ° C. for 10 minutes.
- the composition of the electroless palladium plating solution for forming palladium particles is as follows. Palladium chloride ... 0.07g / L Ethylenediamine ... 0.05g / L Sodium formate ... 0.2g / L Tartaric acid ... 0.11 g / L pH ... 7
- Step m Formation of Electroless Nickel Plating Precipitation Nuclei Particle F (12 g) obtained in Step 1 was washed with water and filtered, and then dispersed in 3000 mL of water heated to 70 ° C. To this dispersion, 3 mL of a 1 g / L bismuth nitrate aqueous solution was added as a plating stabilizer. Subsequently, 60 mL of electroless nickel plating solution for forming a precipitation nucleus having the following composition was dropped at a dropping rate of 15 mL / min. After 10 minutes had elapsed after the completion of the dropping, the dispersion with the plating solution added was filtered.
- the filtrate was washed with water and then dried with a vacuum dryer at 80 ° C. In this way, electroless nickel plating precipitation nuclei made of a nickel-phosphorus alloy having an average length of 56 nm were formed.
- the particle G obtained by forming the electroless nickel plating precipitation nucleus was 13.5 g.
- the composition of the electroless nickel plating solution for forming precipitation nuclei is as follows. Nickel sulfate ... 400g / L Sodium hypophosphite ... 150g / L Sodium tartrate dihydrate ... 120g / L Bismuth nitrate aqueous solution (1 g / L) ... 1 mL / L
- Step n Formation of second layer Particle G (13.5 g) obtained in step m was washed with water and filtered, and then dispersed in 1000 mL of water heated to 70 ° C. To this dispersion, 3 mL of a 1 g / L bismuth nitrate aqueous solution was added as a plating stabilizer. Next, 60 mL of an electroless nickel plating solution for forming a second layer having the following composition was dropped at a dropping rate of 15 mL / min. After 10 minutes had elapsed after the completion of the dropping, the dispersion with the plating solution added was filtered. The filtrate was washed with water and then dried with a vacuum dryer at 80 ° C.
- the composition of the electroless nickel plating solution for forming the second layer is as follows. Nickel sulfate ... 400g / L Sodium hypophosphite ... 150g / L Sodium tartrate dihydrate ... 120g / L Bismuth nitrate aqueous solution (1 g / L) ... 1 mL / L
- Conductive particles were obtained by the above steps j to n.
- Example 2 Conductive particles, insulating coated conductive particles, anisotropic conductive adhesive film, as in Example 1 except that only the second insulating particles of Example 1 were used without using the first insulating particles of Example 1.
- the connection structure was manufactured, and the insulating coated conductive particles and the connection structure were evaluated. The results are shown in Table 5-1 and Table 10-1.
- insulating particles As the first insulating particles, conductive particles, insulating coated conductive particles, anisotropic conductive materials were used in the same manner as in Example 1 except that insulating particles (insulating particle No. 4) having an average particle diameter of 145 nm shown in Table 6 were used. Of the conductive adhesive film and the connection structure, and evaluation of the insulating coated conductive particles and the connection structure were performed. The results are shown in Table 5-1 and Table 10-1.
- Example 4 The same procedure as in Example 1 was performed except that insulating particles (silica particle No. 1) made of gas phase method hydrophilic spherical silica powder having an average particle diameter of 25 nm shown in Table 7-1 were used as the second insulating particles.
- the conductive particles, the insulating coated conductive particles, the anisotropic conductive adhesive film and the connection structure were prepared, and the insulating coated conductive particles and the connection structure were evaluated. The results are shown in Table 5-2 and Table 10-2.
- Example 2 was the same as Example 1 except that insulating particles (silica particle No. 7) made of vapor-phase hydrophilic spherical silica powder having an average particle diameter of 150 nm shown in Table 7-2 were used as the second insulating particles.
- the conductive particles, the insulating coated conductive particles, the anisotropic conductive adhesive film and the connection structure were prepared, and the insulating coated conductive particles and the connection structure were evaluated. The results are shown in Table 5-2 and Table 10-2.
- insulating particles As the second insulating particles, insulating particles (insulating particles No. 5) having an average particle diameter of 100 nm shown in Table 6 were used. As the insulating particles having an average particle diameter of 100 nm, those treated with a silicone oligomer were used. Except having used the said insulating particle, it carried out similarly to Example 1, and produced conductive particle, insulation coating conductive particle, anisotropic conductive adhesive film, and connection structure, and evaluation of insulation coating conductive particle and connection structure Went. The results are shown in Table 5-2 and Table 10-2. Comparative Example 6 corresponds to the conductive particles of Patent Document 6.
- SYMBOLS 1 Conductive particle, 100a, 100b, 100c, 100d ... Insulation covering conductive particle, 101 ... Resin particle, 102 ... Nonelectroconductive inorganic particle, 103 ... Composite particle, 104 ... 1st layer, 105 ... 2nd layer, 106 ... Palladium particles, 107 ... nickel particles, 108 ... first layer, 108a ... first coating layer, 108b ... second coating layer, 109 ... projections, 210 ... insulating particles, 210a ... first insulating particles, 210b ... second insulating particles , 300 ... connection structure, 310 ... first circuit member, 311, 321 ... circuit board, 311a, 321a ... main surface, 312, 322 ... circuit electrode, 320 ... second circuit member, 330 ... connection part, 330a ... different Directional conductive adhesive, 332... Cured product, 332a.
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Abstract
Description
以下、第1実施形態に係る絶縁被覆導電粒子について説明する。
図1は、第1実施形態に係る絶縁被覆導電粒子を示す模式断面図である。図1に示す絶縁被覆導電粒子100aは、導電粒子1のコアを構成する樹脂粒子101と、樹脂粒子101に付着する非導電性無機粒子102と、樹脂粒子101及び非導電性無機粒子102を覆う金属層である第1層104と、第1層104に付着する絶縁粒子210とを備える。第1層104の外表面には、樹脂粒子101に接着された非導電性無機粒子102の形状を反映する突起109が形成される。以下では、樹脂粒子101と非導電性無機粒子102とを組み合わせた粒子を複合粒子103とも呼称し、複合粒子103と第1層104とを組み合わせた粒子を導電粒子1とも呼称する。第1層104は、金属を少なくとも含む導電層である。第1層104は、金属層でもよいし、合金層でもよい。絶縁粒子210は、200nm以上500nm以下の平均粒径を有する第1絶縁粒子210aと、30nm以上130nm以下の平均粒径を有し、シリカからなる第2絶縁粒子210bとを含有する。
絶縁被覆導電粒子100aの平均粒径は、例えば、1μm以上でもよく、2μm以上でもよい。絶縁被覆導電粒子100aの平均粒径は、例えば、10μm以下でもよく、5μm以下でもよい。つまり、絶縁被覆導電粒子100aの平均粒径は、例えば、1~10μmである。絶縁被覆導電粒子100aの平均粒径が上記範囲内であることにより、例えば、絶縁被覆導電粒子100aを含む異方導電性接着剤を用いて接続構造体を作製した場合に、当該接続構造体の電極の形状(高さ)のばらつきによる導電性が変化しにくくなる。絶縁被覆導電粒子100aの平均粒径は、走査型電子顕微鏡(以下、「SEM」と言う)を用いた観察により任意の絶縁被覆導電粒子300個の粒径の測定を行うことにより得られる平均値としてもよい。絶縁被覆導電粒子100aは突起109及び絶縁粒子210を有するため、絶縁被覆導電粒子100aの粒径は、SEMにて撮影した画像において絶縁被覆導電粒子100aに外接する円の直径とする。精度を上げて絶縁被覆導電粒子100aの平均粒径を測定するためには、コールターカウンター等の市販の装置を用いることができる。この場合、絶縁被覆導電粒子50000個の粒径の測定を行えば、高い精度で平均粒径を測定することができる。例えば、COULER MULTISIZER II(ベックマン・コールター株式会社製、商品名)により50000個の絶縁被覆導電粒子を測定することにより、絶縁被覆導電粒子100aの平均粒径を測定してもよい。
絶縁被覆導電粒子100aの単分散率は、96.0%以上でもよく、98.0%以上でもよい。絶縁被覆導電粒子100aの単分散率が上記範囲内であることにより、例えば、吸湿試験後において高い絶縁信頼性を得ることができる。絶縁被覆導電粒子100aの単分散率は、例えば、50,000個の導電粒子を用いて、COULER MULTISIZER II(ベックマン・コールター株式会社製、商品名)により測定することができる。
樹脂粒子101は、有機樹脂から構成される。有機樹脂としては、ポリメチルメタクリレート、ポリメチルアクリレート等の(メタ)アクリル樹脂;ポリエチレン、ポリプロピレン等のポリオレフィン樹脂;ポリイソブチレン樹脂;ポリブタジエン樹脂などが挙げられる。樹脂粒子101としては、架橋(メタ)アクリル粒子、架橋ポリスチレン粒子等の有機樹脂を架橋して得られた粒子も使用できる。樹脂粒子は、上記有機樹脂の一種から構成されてもよいし、上記有機樹脂の二種以上を組み合わせて構成されてもよい。有機樹脂は、上記樹脂に限定されない。
樹脂粒子101には、表面処理としてカチオン性ポリマーが被覆されることがある。このカチオン性ポリマーとしては、一般に、ポリアミン等のように正荷電を帯びることのできる官能基を有する高分子化合物が挙げられる。カチオン性ポリマーは、例えば、ポリアミン、ポリイミン、ポリアミド、ポリジアリルジメチルアンモニウムクロリド、ポリビニルアミン、ポリビニルピリジン、ポリビニルイミダゾール、及びポリビニルピロリドンからなる群より選ばれてもよい。電荷密度が高く、負の電荷を持った表面及び材料との結合力が強い観点から、ポリイミンが好ましく、ポリエチレンイミンがより好ましい。カチオン性ポリマーは、水、又は、水と有機溶媒との混合溶液に可溶であることが好ましい。カチオン性ポリマーの分子量は、用いるカチオン性ポリマーの種類により変化するが、例えば、500~200000程度である。
非導電性無機粒子102は、突起109の芯となる粒子であり、例えば、静電気力により樹脂粒子101に接着されている。非導電性無機粒子102の形状は、特に制限されないが、楕円体、球体、半球体、略楕円体、略球体、略半球体等である。これらの中でも楕円体又は球体であることが好ましい。
樹脂粒子101への非導電性無機粒子102の接着は、有機溶媒、あるいは、水と水溶性の有機溶媒との混合溶液を用いて行うことができる。使用できる水溶性の有機溶媒としては、メタノール、エタノール、プロパノール、アセトン、ジメチルホルムアミド、アセトニトリル等が挙げられる。非導電性無機粒子102に疎水化処理剤が被覆され、樹脂粒子101にカチオン性ポリマーが被覆されることにより、非導電性無機粒子102と樹脂粒子101とは静電気力によって接合してもよい。
複合粒子103を被覆する金属層は、単層構造でもよく、複数の層を有する積層構造でもよい。第1実施形態における金属層が単層構造の第1層104である場合、当該第1層104は、めっき層でもよい。第1層104としては、コスト、導通信頼性及び耐腐食性の観点からニッケルを主成分として含む導電層であってもよい。近年のガラス上に設けられる電極の平坦性を考慮すると、導通信頼性を向上するため、その表面が突起109を有するように第1層104が設けられてもよい。
本実施形態においては、第1層104は、無電解ニッケルめっきにより形成される。この場合、無電解ニッケルめっき液は、水溶性ニッケル化合物を含む。無電解ニッケルめっき液は、安定剤(例えば、硝酸ビスマス)、錯化剤、還元剤、pH調整剤及び界面活性剤からなる群より選択される少なくとも一種の化合物を更に含んでもよい。
第1層104を上述した無電解ニッケルめっきにより形成する場合、複合粒子103に対して予め前処理としてパラジウム触媒化処理してもよい。パラジウム触媒化処理は、公知の方法で行うことができる。例えば、アルカリシーダ又は酸性シーダと呼ばれる触媒化処理液を用いた触媒化処理方法によって上記前処理が行われてもよい。
導電粒子1の表面(具体的には、第1層104の表面)には、非導電性無機粒子102の形状を反映した突起109が形成されている。非導電性無機粒子102及び第1層104を含む突起109(例えば導電粒子1の外表面を構成する第1層104を含む突起109)を、直径(外径)が100nm未満の第1突起と、直径が100nm以上200nm未満の第2突起と、直径が200nm以上350nm以下の第3突起とに分類する。この場合、全突起数における第1突起の割合が80%未満でもよく、全突起数における第2突起の割合が20~80%でもよく、全突起数における第3突起の割合が10%以下でもよい。全突起数における第1突起の割合が60%未満でもよく、全突起数における第2突起の割合が40~70%でもよく、全突起数における第3突起の割合が5%以下でもよい。全突起数における第1~第3突起の割合が上記範囲内である絶縁被覆導電粒子100aは、異方導電性接着剤に配合される絶縁被覆導電粒子として用いられたときに、優れた導通信頼性及び絶縁信頼性を更に高度に両立することができる。「全突起数」とは、導電粒子の直径の1/2の直径を有する同心円内に存在する突起の合計数である。
導電粒子1の表面(具体的には、第1層104の表面)に突起109を形成させる方法として、例えば、めっきの異常析出による方法と、芯材を用いる方法とが挙げられる。突起形状を考慮した場合、芯材を用いる方法の採用が好ましい。芯材は、例えば、ニッケル、炭素、パラジウム、金等の導電性材料でもよく、プラスチック、シリカ、酸化チタン等の非導電性材料でもよい。芯材に非磁性材料を用いると、絶縁粒子210を被覆する段階で磁性凝集が発生せず、絶縁粒子210を導電粒子1に容易に付着させられる傾向にある。このため、芯材として強磁性材料であるニッケルを用いる場合、芯材は更にリン等の非磁性材料を含んでもよい。第1実施形態では、突起109の形成方法として、非導電性無機粒子102を芯材とする方法が用いられる。これにより、突起109の大きさの制御が可能となり、良好な形状を有する突起109を形成することが可能なため、絶縁信頼性及び導通信頼性を両立させることができる。また、非導電性無機粒子102を用いることによって、導電粒子1を高圧縮した場合であっても、非導電性無機粒子102の上部に形成された突起109を構成する第1層104が押しつぶされることが抑制される。このため、例えば絶縁粒子210としてシリカを用いた場合であっても、電極等に圧着接続した場合に、第1層104の潰れを抑制し、低い導通抵抗を得ることが可能となる。
上述したように絶縁粒子210は、200nm以上500nm以下の平均粒径を有する第1絶縁粒子210aと、30nm以上130nm以下の平均粒径を有し、シリカからなる第2絶縁粒子210bとを含有する。
第1絶縁粒子210aの平均粒径は、200nm以上500nm以下である。第1絶縁粒子210aの平均粒径が200nm以上である場合、第1絶縁粒子210aが絶縁スペーサーとして充分機能し、より優れた絶縁信頼性が得られる。第1絶縁粒子210aの平均粒径が500nm以下であると、第1絶縁粒子210aを容易に導電粒子1に付着することができる。
第2絶縁粒子210bの平均粒径は、30nm以上130nm以下である。第2絶縁粒子210bの平均粒径は、25nmよりも大きくてもよく、100nm以下であってもよい。第2絶縁粒子210bの平均粒径が30nm以上である場合、第2絶縁粒子210bが絶縁スペーサーとして充分機能し、より優れる絶縁信頼性が得られる。第2絶縁粒子210bの平均粒径が130nm以下である場合、第2絶縁粒子210bを容易に導電粒子1に付着することができる。
絶縁粒子210を導電粒子1に付着させる方法としては、特に限定されない。例えば、官能基付きの導電粒子1に官能基付きの絶縁粒子210を付着させる方法等が挙げられる。この場合、絶縁粒子210は、外表面に水酸基、シラノール基、カルボキシル基等の反応性が良好な官能基を有していることが好ましい。
第2絶縁粒子210bを被覆する疎水化処理剤としては、以下に記載の、(1)シラザン系疎水化処理剤、(2)シロキサン系疎水化処理剤、(3)シラン系疎水化処理剤、(4)チタネート系疎水化処理剤等が挙げられる。反応性の観点から(1)シラザン系疎水化処理剤が好ましい。疎水化処理剤は、上記(1)~(4)からなる群から選択される少なくとも一種を含んでもよい。
シラザン系疎水化処理剤としては、有機シラザン系疎水化処理剤が挙げられる。有機シラザン系疎水化処理剤としては、ヘキサメチルジシラザン、トリメチルジシラザン、テトラメチルジシラザン、ヘキサメチルシクロトリシラザン、ヘプタメチルジシラザン、ジフェニルテトラメチルジシラザン、ジビニルテトラメチルジシラザン等が挙げられる。有機シラザン系疎水化処理剤は、上記以外のものでもよい。
シロキサン系疎水化処理剤としては、ポリジメチルシロキサン、メチルハイドロジェンジシロキサン、ジメチルジシロキサン、ヘキサメチルジシロキサン、1,3-ジビニルテトラメチルジシロキサン、1,3-ジフェニルテトラメチルジシロキサン、メチルハイドロジェンポリシロキサン、ジメチルポリシロキサン、アミノ変性シロキサン等が挙げられる。シロキサン系疎水化処理剤は、上記以外のものでもよい。
シラン系疎水化処理剤としては、N,N-ジメチルアミノトリメチルシラン、トリメチルメトキシシラン、トリメチルエトキシシラン、トリメチルプロポキシシラン、フェニルジメチルメトキシシラン、クロロプロピルジメチルメトキシシラン、ジメチルジメトキシシラン、メチルトリメトキシシラン、テトラメトキシシラン、テトラエトキシシラン、テトラプロポキシシラン、テトラブトキシシラン、エチルトリメトキシシラン、ジメチルジエトキシシラン、プロピルトリエトキシシラン、n-ブチルトリメトキシシラン、n-ヘキシルトリメトキシシラン、n-オクチルトリエトキシシラン、n-オクチルメチルジエトキシシラン、n-オクタデシルトリメトキシシラン、フェニルトリメトキシシラン、フェニルメチルジメトキシシラン、フェネチルトリメトキシシラン、ドデシルトリメトキシシラン、n-オクタデシルトリエトキシシラン、フェニルトリメトキシシラン、ジフェニルジメトキシシラン、ビニルトリメトキシシラン、ビニルトリエトキシシラン、ビニルトリス(βメトキシエトキシ)シラン、γ-メタアクリルオキシプロピルトリメトキシシラン、γ-アクリルオキシプロピルトリメトキシシラン、γ-(メタアクリルオキシプロピル)メチルジメトキシシラン、γ-メタアクリルオキシプロピルメチルジエトキシシラン、γ-メタアクリルオキシプロピルトリエトキシシラン、β-(3,4-エポキシシクロヘキシル)エチルトリメトキシシラン、γ-グリシドキシプロピルトリメトキシシラン、γ-グリシドキシプロピルメチルジエトキシシラン、γ-グリシドキシプロピルトリエトキシシラン、N-β(アミノエチル)γ-(アミノプロピル)メチルジメトキシシラン、N-β(アミノエチル)γ-(アミノプロピル)トリメトキシシラン、N-β(アミノエチル)γ-(アミノプロピル)トリエトキシシラン、γ-アミノプロピルトリメトキシシラン、γ-アミノプロピルトリエトキシシラン、N-フェニル-γ-アミノプロピルトリメトキシシラン、γ-メルカプトプロピルトリメトキシシラン、3-イソシアネートプロピルトリエトキシシラン、トリフルオロプロピルトリメトキシシラン、ヘプタデカトリフルオロプロピルトリメトキシシラン、n-デシルトリメトキシシラン、ジメトキシジエトキシシラン、ビス(トリエトキシシリル)エタン、ヘキサエトキシジシロキサン等が挙げられる。
チタネート系疎水化処理剤としては、KRTTS、KR46B、KR55、KR41B、KR38S、KR138S、KR238S、338X、KR44、KR9SA(いずれも、味の素ファインテクノ株式会社製、商品名)等が挙げられる。
疎水化処理剤が被覆された第2絶縁粒子210bのメタノール滴定法による疎水化度は、例えば、30%以上でもよく、50%以上でもよく、60%以上でもよい。第2絶縁粒子210bの疎水化度が高いほど、第2絶縁粒子210bゼータ電位がよりマイナスになる。このため、第2絶縁粒子210bは、高分子電解質により処理された導電粒子1と、静電気力により強固に接着することが可能である。
絶縁粒子210における第1絶縁粒子210aの被覆率は、例えば、導電粒子1の総表面積に対して20~50%である。第1絶縁粒子210aの被覆率が20%以上であると、より良好な絶縁信頼性が得られる。一方、被覆率が50%以下であると、より優れた導通信頼性が得られる。
以下では、第2実施形態に係る絶縁被覆導電粒子について説明する。第2実施形態の説明において第1実施形態と重複する記載は省略し、第1実施形態と異なる部分を記載する。つまり、技術的に可能な範囲において、第2実施形態に第1実施形態の記載を適宜用いてもよい。
第2層105は、第1層104を被覆して設けられる導電層である。第2層105の厚さは、例えば、5nm~100nmである。第2層105の厚さは、5nm以上でもよく、10nm以上でもよい。第2層105の厚さは、30nm以下でもよい。第2層105の厚さが上記範囲内である場合、第2層105を形成する場合に当該第2層105の厚さを均一にできる、これにより、第1層104に含有される元素(例えば、ニッケル)が、第2層105とは反対側の表面へ拡散することを良好に防止できる。
第2層105がパラジウムを含有する場合、当該第2層105は、例えば、無電解パラジウムめっきによって形成することできる。無電解パラジウムめっきは、還元剤を用いない置換型、及び、還元剤を用いる還元型のいずれを用いてもよい。このような無電解パラジウムめっき液としては、置換型ではMCA(株式会社ワールドメタル製、商品名)等が挙げられる。還元型ではAPP(石原ケミカル株式会社製、商品名)等が挙げられる。置換型と還元型とを比較した場合、生じるボイドが少なく、被覆面積を確保し易い観点から、還元型が好ましい。
第2層105がロジウムを含有する場合、当該第2層105は、例えば、無電解ロジウムめっきによって形成することできる。無電解ロジウムめっき液に用いるロジウムの供給源としては、例えば、水酸化アンミンロジウム、硝酸アンミンロジウム、酢酸アンミンロジウム、硫酸アンミンロジウム、亜硫酸アンミンロジウム、アンミンロジウム臭化物、及び、アンミンロジウム化合物が挙げられる。
第2層105がイリジウムを含有する場合、当該第2層105は、例えば、無電解イリジウムめっきによって形成することできる。無電解イリジウムめっき液に用いるイリジウムの供給源としては、例えば、三塩化イリジウム、四塩化イリジウム、三臭化イリジウム、四臭化イリジウム、六塩化イリジウム三カリウム、六塩化イリジウム二カリウム、六塩化イリジウム三ナトリウム、六塩化イリジウム二ナトリウム、六臭化イリジウム三カリウム、六臭化イリジウム二カリウム、六ヨウ化イリジウム三カリウム、トリス硫酸二イリジウム、及び、ビス硫酸イリジウムが挙げられる。
第2層105がルテニウムを含有する場合、当該第2層105は、例えば、無電解ルテニウムめっきによって形成することできる。無電解ルテニウムめっき液としては、例えば、市販のめっき液を用いることが可能であり、無電解ルテニウムRu(奥野製薬工業株式会社製、商品名)を用いることができる。
第2層105が白金を含有する場合、当該第2層105は、例えば、無電解白金めっきによって形成することできる。無電解白金めっき液に用いる白金の供給源としては、例えば、Pt(NH3)4(NO3)2、Pt(NH3)4(OH)2、PtCl2(NH3)2、Pt(NH3)2(OH)2、(NH4)2PtCl6、(NH4)2PtCl4、Pt(NH3)2Cl4、H2PtCl6、及び、PtCl2が挙げられる。
第2層105が銀を含有する場合、当該第2層105は、例えば、無電解銀めっきによって形成することできる。無電解銀めっき液に用いる銀の供給源としては、めっき液に可溶であるものであれば特に限定されない。例えば、硝酸銀、酸化銀、硫酸銀、塩化銀、亜硫酸銀、炭酸銀、酢酸銀、乳酸銀、スルホコハク酸銀、スルホン酸銀、スルファミン酸銀、及び、シュウ酸銀が用いられる。水溶性銀化合物は、一種を単独で又は二種以上を組み合わせて用いることができる。
第2層105が金を含有する場合、当該第2層105は、例えば、無電解金めっきによって形成することできる。無電解金めっき液としては、置換型金めっき液(例えば、日立化成株式会社製、商品名「HGS-100」)、還元型金めっき液(例えば、日立化成株式会社製、商品名「HGS-2000」)等を用いることができる。置換型と還元型とを比較した場合、ボイドが少なく、被覆面積を確保し易い観点から、還元型を用いることが好ましい。
第2層105がコバルトを含有する場合、当該第2層105は、例えば、無電解コバルトめっきによって形成することできる。無電解コバルトめっき液に用いるコバルトの供給源としては、例えば、硫酸コバルト、塩化コバルト、硝酸コバルト、酢酸コバルト、炭酸コバルトが挙げられる。
以下では、第3実施形態に係る絶縁被覆導電粒子について説明する。第3実施形態の説明において第1実施形態及び第2実施形態と重複する記載は省略し、第1実施形態及び第2実施形態と異なる部分を記載する。つまり、技術的に可能な範囲において、第3実施形態に第1実施形態及び第2実施形態の記載を適宜用いてもよい。
第1被覆層108aは、例えば、ニッケルを主成分とする金属に加えて、リン及びホウ素からなる群より選ばれる少なくとも一種を含有してもよい。この場合、第1被覆層108aは、リンを含有することが好ましい。これにより、第1被覆層108aの硬度を高めることが可能であり、導電粒子1が圧縮されたときの導通抵抗を容易に低く保つことができる。
第2被覆層108bは、ニッケルを含有していることが好ましい。図3に示されるように、第2被覆層108bは、突起109の最外層を構成している。このような第2被覆層108bは、例えば、無電解ニッケルめっきにより形成することができる。例えば、第1被覆層108a及びニッケル粒子107上に無電解ニッケルめっきを施すことにより、突起109を外表面に有する第2被覆層108bを形成することができる。
以下では、第4実施形態に係る絶縁被覆導電粒子について説明する。第4実施形態の説明において第1実施形態~第3実施形態と重複する記載は省略し、第1実施形態~第3実施形態と異なる部分を記載する。つまり、技術的に可能な範囲において、第4実施形態に第1実施形態~第3実施形態の記載を適宜用いてもよい。
以下では、第5実施形態に係る異方導電性接着剤について説明する。第5実施形態の説明において第1実施形態~第4実施形態と重複する記載は省略し、第1実施形態~第4実施形態と異なる部分を記載する。つまり、技術的に可能な範囲において、第5実施形態に第1実施形態~第4実施形態の記載を適宜用いてもよい。
第5実施形態に係る異方導電性接着剤は、第1実施形態に係る絶縁被覆導電粒子100aと、当該絶縁被覆導電粒子100aが分散された接着剤とを含有する。
以下では、第6実施形態に係る接続構造体について説明する。第6実施形態の説明において第1実施形態~第5実施形態と重複する記載は省略し、第1実施形態~第5実施形態と異なる部分を記載する。つまり、技術的に可能な範囲において、第6実施形態に第1実施形態~第5実施形態の記載を適宜用いてもよい。
第6実施形態に係る接続構造体について説明する。本実施形態に係る接続構造体は、第1回路電極を有する第1回路部材と、第2回路電極を有する第2回路部材と、第1回路部材と第2回路部材との間に配置され、絶縁被覆導電粒子が分散している接続部と、を備えている。接続部は、第1回路電極と第2回路電極とが対向するように配置された状態で第1回路部材及び第2回路部材を互いに接続している。第1回路電極及び第2回路電極は、変形した状態の絶縁被覆導電粒子を介して互いに電気的に接続されている。
第6実施形態に係る接続構造体の製造方法について、図6を参照しながら説明する。図6は、図5に示す接続構造体の製造方法の一例を説明するための模式断面図である。第6実施形態では、異方導電性接着剤を熱硬化させて接続構造体を製造する。
[導電粒子の作製]
(工程a)樹脂粒子表面のカチオン性ポリマーによる被覆
平均粒径3.0μmの架橋ポリスチレン粒子(株式会社日本触媒製、商品名「ソリオスター」)6gを、平均分子量7万(M.W.7万)の30質量%ポリエチレンイミン水溶液(和光純薬工業株式会社製)9gを純水300mlに溶解した水溶液に加え、室温で15分間攪拌した。次いで、φ3μmのメンブレンフィルタ(メルクミリポア社製)を用いた濾過により、樹脂粒子を取り出した。メンブレンフィルタ上の樹脂粒子を600gの超純水で2回洗浄し、吸着していないポリエチレンイミンを除去して、ポリエチレンイミンが吸着した樹脂粒子を得た。
非導電性無機粒子として、平均粒径60nmの気相法親水性球状シリカ粉末を用いた。この球状シリカ粉末100gを振動流動層装置(中央化工機株式会社製、商品名「振動流動層装置VUA-15型」)に収容した。次に、吸引ブロワーにより循環させた空気で球状シリカを流動化させながら水1.5gを噴霧して5分間流動混合させた。次に、HMDS(ヘキサメチレンジシラザン)(モメンティブ・パフォーマンス・マテリアルズ・ジャパン合同会社製、商品名「TSL-8802」)2.5gを噴霧し、30分間流動混合した。得られた疎水性球状シリカ微粉体の疎水化度を、メタノール滴定法によって測定した。疎水化度は以下の方法で測定し、非導電性無機粒子の疎水化度は70%であった。
ポリエチレンイミンが吸着した樹脂粒子6gをメタノールに加え、共振周波数28kHz、出力100Wの超音波を照射しながら室温で5分間攪拌した。その後、HMDSにより疎水化された球状シリカ粉末0.15gを上記メタノールに加え、共振周波数28kHz、出力100Wの超音波を照射しながらさらに室温で5分間攪拌した。これにより、非導電性無機粒子が静電気により吸着された樹脂粒子(粒子a)を得た。非導電性無機粒子が静電気により吸着された粒子Aは6.15gであった。
粒子A6.15gを、pH1.0に調整され、パラジウム触媒(日立化成株式会社製、商品名「HS201」)を20質量%含有するパラジウム触媒化液300mLに添加した。その後、共振周波数28kHz、出力100Wの超音波を照射しながら30℃で30分間攪拌した。次に、φ3μmのメンブレンフィルタ(メルクミリポア社製)で濾過した後、水洗を行うことでパラジウム触媒を粒子Aの表面に吸着させた。その後、pH6.0に調整された0.5質量%ジメチルアミンボラン液に粒子Aを添加し、共振周波数28kHz、出力100Wの超音波を照射しながら60℃で5分間攪拌し、パラジウム触媒が固着化された粒子B6.15gを得た。そして、20mLの蒸留水に、パラジウム触媒が固着化された粒子B6.15gを浸漬した後、粒子Bを超音波分散することで、樹脂粒子分散液を得た。図7、図8に、球状シリカ粉末を吸着させた樹脂粒子の表面を、SEM(株式会社日立ハイテクノロジーズ製、商品名「S-4800」)により観察した結果を示す。
工程dで得た粒子B分散液を、80℃に加温した水3000mLで希釈した後、めっき安定剤として1g/Lの硝酸ビスマス水溶液を3mL添加した。次に、粒子B分散液に、下記組成(下記成分を含む水溶液。1g/Lの硝酸ビスマス水溶液をめっき液1Lあたり1mL添加している。以下同様)の第1層形成用無電解ニッケルめっき液240mLを15mL/分の滴下速度で滴下した。滴下終了後、10分間経過した後に、めっき液を加えた分散液を濾過した。濾過物を水で洗浄した後、80℃の真空乾燥機で乾燥した。このようにして、表1-1に示す80nmの膜厚のニッケル-リン合金被膜からなる第1層(上記実施形態における第1被覆層に相当)を有する粒子Cを形成した。第1層を形成することにより得た粒子Cは、12.15gであった。第1層形成用の無電解ニッケルめっき液の組成は以下の通りである。
硫酸ニッケル・・・・・・・・・・・・400g/L
次亜リン酸ナトリウム・・・・・・・・150g/L
クエン酸ナトリウム・・・・・・・・・120g/L
硝酸ビスマス水溶液(1g/L)・・・1mL/L
工程eで得た粒子C12.15gを、水洗及び濾過した後、70℃に加温した水3000mLに分散させた。この分散液に、めっき安定剤として1g/Lの硝酸ビスマス水溶液を3mL添加した。次いで、下記組成の第2層形成用無電解ニッケルめっき液60mLを15mL/分の滴下速度で滴下した。滴下終了後、10分間経過した後に、めっき液を加えた分散液を濾過した。濾過物を水で洗浄した後、80℃の真空乾燥機で乾燥した。このようにして、表1-1に示す20nmの膜厚のニッケル-リン合金被膜からなる第2層(上記実施形態における第2被覆層に相当)を有する粒子Dを形成した。第2層を形成することにより得た粒子Dは、13.65gであった。第2層形成用の無電解ニッケルめっき液の組成は以下の通りである。
硫酸ニッケル・・・・・・・・・・・・400g/L
次亜リン酸ナトリウム・・・・・・・・150g/L
酒石酸ナトリウム・2水和物・・・・・60g/L
硝酸ビスマス水溶液(1g/L)・・・1mL/L
下記の項目に基づき導電粒子を評価した。結果を表1-1に示す。
得られた導電粒子の中心付近を通るようにウルトラミクロトーム法で断面を切り出した。この断面を、TEM(日本電子株式会社製、商品名「JEM-2100F」)を用いて25万倍の倍率で観察した。得られた画像から、第1層、第2層及び第3層の断面積を見積り、その断面積から第1層、第2層及び第3層の膜厚を算出した。実施例1~16,19、及び比較例1~5においては、第3層が形成されていないことから、これらの実施例及び比較例については第1層、第2層の膜厚のみを測定の対象とした。断面積に基づく各層の膜厚の算出では、幅500nmの断面における各層の断面積を画像解析により読み取り、幅500nmの長方形に換算した場合の高さを各層の膜厚として算出した。表1-1には、10個の導電粒子について算出した膜厚の平均値を示した。このとき、第1層、第2層及び第3層を区別しづらい場合には、TEMに付属するEDX(日本電子株式会社製、商品名「JED-2300」)による成分分析により、第1層、第2層及び第3層を明確に区別することで、断面積を見積もり、膜厚を計測した。EDXマッピングデータから、第1層、第2層及び第3層における元素の含有量(純度)を算出した。薄膜切片状のサンプル(導電粒子の断面試料)の作製方法の詳細、EDXによるマッピングの方法の詳細、及び、各層における元素の含有量の算出方法の詳細については後述する。
{突起の被覆率}
導電粒子をSEMにより3万倍で観察して得られるSEM画像をもとに、導電粒子表面における突起による被覆率(面積の割合)を算出した。具体的には、導電粒子の正投影面における導電粒子の直径の1/2の直径を有する同心円内において突起形成部と平坦部とを画像解析により区別した。そして、同心円内に存在する突起形成部の面積の割合を算出し、当該割合を突起の被覆率とした。図9に、実施例1における粒子DをSEMにより観察した結果を示す。
導電粒子の正投影面において、導電粒子の直径の1/2の直径を有する同心円内に存在する突起による被覆率と、所定の直径を有する突起の数とを算出した。
導電粒子の断面試料の作製方法の詳細について説明する。導電粒子の断面からTEM分析及びSTEM/EDX分析するための60nm±20nmの厚さを有する断面試料(以下、「TEM測定用の薄膜切片」という)を、ウルトラミクロトーム法を用いて下記のとおり作製した。
EDXによるマッピングの方法の詳細について説明する。TEM測定用の薄膜切片を銅メッシュごと試料ホルダー(日本電子株式会社製、商品名「ベリリウム試料2軸傾斜ホルダー、EM-31640」)に固定し、TEM内部へ挿入した。加速電圧200kVにて、試料への電子線照射を開始した後、電子線の照射系をSTEMモードに切り替えた。
導電粒子0.05gを電解水に分散させ、界面活性剤を添加し、超音波分散(アズワン株式会社製、商品名「US-4R」、高周波出力:160W、発振周波数:40kHz単周波)を5分間行った。導電粒子の分散液をCOULER MULTISIZER II(ベックマン・コールター株式会社製、商品名)の試料カップに注入し、導電粒子50000個についての単分散率を測定した。単分散率は下記式により算出し、その値に基づいて下記基準により水溶媒中での粒子の凝集性を判定した。
単分散率(%)={first peak粒子数(個)/全粒子数(個)}×100
500mlフラスコに入った純水400g中に、表6に示す絶縁粒子No.1の配合モル比に従ってモノマーを加えた。全モノマーの総量が、純水に対して10質量%になるように配合した。窒素置換後、70℃で撹拌しながら6時間加熱を行った。攪拌速度は300min-1(300rpm)であった。表6中のKBM-503(信越化学株式会社製、商品名)は、3-メタクリロキシプロピルトリメトキシシランである。
攪拌装置、コンデンサー及び温度計を備えたガラスフラスコに、3-グリシドキシプロピルトリメトキシシラン118gとメタノール5.9gとを配合した溶液を加えた。さらに、活性白土5g及び蒸留水4.8gを添加し、75℃で一定時間攪拌した後、重量平均分子量1300のシリコーンオリゴマーを得た。得られたシリコーンオリゴマーは、水酸基と反応する末端官能基としてメトキシ基又はシラノール基を有するものである。得られたシリコーンオリゴマー溶液にメタノールを加えて、固形分20質量%の処理液を調製した。
第2絶縁粒子として、平均粒径60nmの気相法親水性球状シリカ粉末を用いた。この球状シリカ粉末100gを振動流動層装置(中央化工機株式会社製、商品名「振動流動層装置VUA-15型」)に収容した。次に、吸引ブロワーにより循環させた空気で球状シリカを流動化させながら水1.5gを噴霧して5分間流動混合させた。次に、HMDS(ヘキサメチレンジシラザン)(モメンティブ・パフォーマンス・マテリアルズ・ジャパン合同会社製、商品名「TSL-8802」)2.5gを噴霧し、30分間流動混合した。これにより、表7-1に示されるシリカ粒子No.3を作製した。得られた疎水性球状シリカ微粉体の疎水化度を、メタノール滴定法によって測定した。疎水化度は以下の方法で測定し、第2絶縁粒子の疎水化度は70%であった。第2絶縁粒子の特性をまとめて表7-1及び表7-2に示した。
第2絶縁粒子の疎水化度は以下の方法により測定した。まず、イオン交換水50ml、試料(第2絶縁粒子)0.2gをビーカーに入れ、マグネティックスターラーで攪拌しながらビュレットからメタノールを滴下する。ビーカー内のメタノール濃度が増加するにつれ粉体は徐々に沈降していき、その全量が沈んだ終点におけるメタノール-水混合溶液中のメタノールの質量分率を、第2絶縁粒子の疎水化度(%)とした。
第2絶縁粒子の粒径は、SEMにより10万倍で観察して得られる画像を解析し、粒子500個のそれぞれの面積を測定する。次に、粒子を円に換算した場合の直径を、第2絶縁粒子の平均粒径として算出した。得られた平均粒径に対する、粒径の標準偏差の比をパーセンテージで算出し、CVとした。
第2絶縁粒子のゼータ電位は、以下の方法により測定した。ゼータ電位の測定には、Zetasizer ZS(Malvern Instruments社製、商品名)を用いた。第2絶縁粒子が約0.02質量%になるようにメタノールを用いて分散体を希釈し、ゼータ電位を測定した。
メルカプト酢酸8mmolをメタノール200mlに溶解させて反応液を調製した。次に導電粒子(実施例1においては、粒子D)を10g上記反応液に加え、スリーワンモーターと直径45mmの攪拌羽で、室温で2時間攪拌した。メタノールで洗浄後、孔径3μmのメンブレンフィルタ(メルクミリポア社製)を用いてろ過することで、表面にカルボキシル基を有する導電粒子を10g得た。
絶縁被覆導電粒子の正投影面において、絶縁被覆導電粒子の直径の1/2の直径を有する同心円内に存在する第1絶縁粒子及び第2絶縁粒子の被覆率をそれぞれ算出した。具体的には、絶縁被覆導電粒子の直径の1/2の直径を有する同心円内において、第1絶縁粒子、第2絶縁粒子、及び導電粒子を画像解析により区別し、同心円内に存在する第1絶縁粒子と第2絶縁粒子との面積の割合をそれぞれ算出し、当該割合を第1絶縁粒子と第2絶縁粒子それぞれの被覆率とした。絶縁被覆導電粒子200個における平均値を求めた。
i)異方導電性接着フィルム(2mm×24mm)をIZO回路付きガラス基板に80℃、0.98MPa(10kgf/cm2)で貼り付けた。
ii)セパレータを剥離し、チップのバンプとIZO回路付きガラス基板の位置合わせを行った。
iii)190℃、40gf/バンプ、10秒の条件でチップ上方から加熱及び加圧を行い、チップとガラス基板との接着を行うと共に、チップのバンプとIZO回路との電気的接続を行った。
得られた接続構造体の導通抵抗試験及び絶縁抵抗試験を以下のように行った。
チップ電極(バンプ)とIZO回路との接続において、導通抵抗の初期値と、吸湿耐熱試験(温度85℃、湿度85%の条件で100、300、500、1000、2000時間放置)後の値とを測定した。導通抵抗試験には、接着剤フィルムAとして、単位面積当たり7万個/mm2の絶縁被覆導電粒子を有する接着剤フィルムを用いた。チップ電極(バンプ)とIZO回路との接続領域は、約30μm×約40μm、及び約40μm×約40μmとした。約30μm×約40μmの接続領域においては、チップ電極とIZO回路とは6個の絶縁被覆導電粒子(捕捉絶縁被覆導電粒子)で接続されるように設定した。約40μm×約40μmの接続領域においては、チップ電極とIZO回路とは10個の絶縁被覆導電粒子で接続されるように設定した。なお、20サンプルについて測定し、それらの平均値を算出した。得られた平均値から下記基準に従って導通抵抗を評価した結果を表8-1に示す。バンプ数6個において、吸湿耐熱試験500時間後に下記Aの基準を満たす場合、導通抵抗が良好であると評価した。
A:導通抵抗の平均値が2Ω未満
B:導通抵抗の平均値が2Ω以上5Ω未満
C:導通抵抗の平均値が5Ω以上10Ω未満
D:導通抵抗の平均値が10Ω以上20Ω未満
E:導通抵抗の平均値が20Ω以上
チップ電極間の絶縁抵抗として、絶縁抵抗の初期値と、マイグレーション試験(温度60℃、湿度90%、20V印加の条件で100、300、1000、2000時間放置)後の値とを測定した。導通抵抗試験には、接着剤フィルムAとして、単位面積当たり7万個/mm2の絶縁被覆導電粒子を有する接着剤フィルムと、単位面積当たり10万個/mm2の絶縁被覆導電粒子を有する接着剤フィルムの2種類を用いた。それぞれの絶縁被覆導電粒子を含有するフィルムにおいて、20サンプルずつ測定した。各フィルムの20サンプル中、絶縁抵抗値が109Ω以上となるサンプルの割合を算出した。得られた割合から下記基準に従って絶縁抵抗を評価した。結果を表8-1に示す。10万個/mm2の絶縁被覆導電粒子を有する接着剤フィルムにおいて、吸湿耐熱試験100時間後に下記Aの基準を満たす場合を絶縁抵抗が良好であると評価した。
A:絶縁抵抗値109Ω以上の割合が100%
B:絶縁抵抗値109Ω以上の割合が90%以上100%未満
C:絶縁抵抗値109Ω以上の割合が80%以上90%未満
D:絶縁抵抗値109Ω以上の割合が50%以上80%未満
E:絶縁抵抗値109Ω以上の割合が50%未満
実施例1の第1絶縁粒子の代わりに、表6に示される平均粒径239nmの絶縁粒子(絶縁粒子No.2)に変更したこと以外は実施例1と同様にして、導電粒子、絶縁被覆導電粒子、異方導電性接着フィルム及び接続構造体の作製、並びに、絶縁被覆導電粒子及び接続構造体の評価を行った。結果を表1-1及び表8-1に示す。
実施例1の第1絶縁粒子の代わりに、表6に示される平均粒径402nmの絶縁粒子(絶縁粒子No.3)に変更したこと以外は実施例1と同様にして、導電粒子、絶縁被覆導電粒子、異方導電性接着フィルム及び接続構造体の作製、並びに、絶縁被覆導電粒子及び接続構造体の評価を行った。結果を表1-1及び表8-1に示す。
実施例1の第2絶縁粒子の代わりに、表7-1に示される平均粒径40nmの気相法親水性球状シリカ粉末からなる絶縁粒子(シリカ粒子No.2)に変更したこと以外は実施例1と同様にして、導電粒子、絶縁被覆導電粒子、異方導電性接着フィルム及び接続構造体の作製、並びに、絶縁被覆導電粒子及び接続構造体の評価を行った。結果を表1-1及び表8-1に示す。
実施例1の第2絶縁粒子の代わりに、表7-1に示される平均粒径80nmの気相法親水性球状シリカ粉末からなる絶縁粒子(シリカ粒子No.4)に変更したこと以外は実施例1と同様にして、導電粒子、絶縁被覆導電粒子、異方導電性接着フィルム及び接続構造体の作製、並びに、絶縁被覆導電粒子及び接続構造体の評価を行った。結果を表1-2及び表8-2に示す。
実施例1の第2絶縁粒子の代わりに、表7-1の平均粒径100nmの気相法親水性球状シリカ粉末からなる絶縁粒子(シリカ粒子No.5)に変更したこと以外は実施例1と同様にして、導電粒子、絶縁被覆導電粒子、異方導電性接着フィルム及び接続構造体の作製、並びに、絶縁被覆導電粒子及び接続構造体の評価を行った。結果を表1-2及び表8-2に示す。
実施例1の第2絶縁粒子の代わりに、表7-1に示される平均粒径120nmの気相法親水性球状シリカ粉末からなる絶縁粒子(シリカ粒子No.6)に変更したこと以外は実施例1と同様にして、導電粒子、絶縁被覆導電粒子、異方導電性接着フィルム及び接続構造体の作製、並びに、絶縁被覆導電粒子及び接続構造体の評価を行った。結果を表1-2及び表8-2に示す。図15及び図16に、絶縁被覆導電粒子を被覆した後に観察したSEM画像を示す。図16は、絶縁被覆導電粒子の直径の1/2の直径を有する同心円内の一部分である。
実施例1の(工程i)において、第1絶縁粒子のメタノール分散媒の滴下量を変えることで、第1絶縁粒子の被覆率を表2-1に示した範囲に変更したこと以外は実施例1と同様にして、導電粒子、絶縁被覆導電粒子、異方導電性接着フィルム及び接続構造体の作製、並びに、絶縁被覆導電粒子及び接続構造体の評価を行った。結果を表2-1、表8-2及び表8-3に示す。
実施例1の(工程i)において、第2絶縁粒子のメタノール分散媒の滴下量を変えることで、第2絶縁粒子の被覆率を表2-1及び表2-2に示した範囲に変更したこと以外は実施例1と同様にして、導電粒子、絶縁被覆導電粒子、異方導電性接着フィルム及び接続構造体の作製、並びに、絶縁被覆導電粒子及び接続構造体の評価を行った。結果を表2-1、表2-2及び表9-1に示す。
実施例1の第2絶縁粒子の代わりに、平均粒径40nmのコロイダルシリカ分散液を用いた。具体的には、表7-2に示される、表面が疎水化されていない第2絶縁粒子(シリカ粒子No.8)を用いた。これ以外は実施例1と同様にして、導電粒子、絶縁被覆導電粒子、異方導電性接着フィルム及び接続構造体の作製、並びに、絶縁被覆導電粒子及び接続構造体の評価を行った。結果を表2-2及び表9-1に示す。
実施例1の第2絶縁粒子の代わりに、平均粒径60nmのコロイダルシリカ分散液を用いた。具体的には、表7-2に示される、表面が疎水化されていない第2絶縁粒子(シリカ粒子No.9)を用いた。これ以外は実施例1と同様にして、導電粒子、絶縁被覆導電粒子、異方導電性接着フィルム及び接続構造体の作製、並びに、絶縁被覆導電粒子及び接続構造体の評価を行った。結果を表3-1及び表9-2に示す。
実施例1の第2絶縁粒子の代わりに、平均粒径80nmのコロイダルシリカ分散液を用いた。具体的には、表7-2に示される、表面が疎水化されていない第2絶縁粒子(シリカ粒子No.10)を用いた。これ以外は実施例1と同様にして、導電粒子、絶縁被覆導電粒子、異方導電性接着フィルム及び接続構造体の作製、並びに、絶縁被覆導電粒子及び接続構造体の評価を行った。結果を表3-1及び表9-2に示す。
実施例1の(工程h)の第2絶縁粒子の代わりに、平均粒径100nmのコロイダルシリカ分散液を用いた。具体的には、表7-2に示される、表面が疎水化されていない第2絶縁粒子(シリカ粒子No.11)を用いた。これ以外は実施例1と同様にして、導電粒子、絶縁被覆導電粒子、異方導電性接着フィルム及び接続構造体の作製、並びに、絶縁被覆導電粒子及び接続構造体の評価を行った。結果を表3-1及び表9-2に示す。
実施例1の(工程a~f)によって得た粒子D13.65gを、下記組成の無電解パラジウムめっき液3Lに浸漬して第3層(上記実施形態における第2層に相当)を形成することによって、表3-1に示される導電粒子を得た。反応時間は10分間、温度は50℃にて処理を行った。第3層の平均厚さは10nmであり、第3層におけるパラジウム含有量は100質量%であった。この導電粒子を用いたこと以外は実施例1と同様にして、絶縁被覆導電粒子、異方導電性接着フィルム及び接続構造体の作製、並びに、絶縁被覆導電粒子及び接続構造体の評価を行った。結果を表3-1及び表9-2に示す。無電解パラジウムめっき液の組成は以下の通りである。
塩化パラジウム・・・・・・・0.07g/L
EDTA・2ナトリウム・・・1g/L
クエン酸・2ナトリウム・・・1g/L
ギ酸ナトリウム・・・・・・・0.2g/L
pH・・・・・・・・・・・・6
実施例1の(工程a~f)によって粒子D13.65gを、置換金めっき液(日立化成株式会社製、商品名「HGS-100」)100mL/Lの溶液3Lに、85℃で2分間浸漬し、更に2分間水洗して、第3層を形成した。反応時間は10分間、温度は60℃にて処理を行った。第3層の平均厚さは10nm、第3層における金含有量はほぼ100質量%であった。この導電粒子を用いたこと以外は実施例1と同様にして、絶縁被覆導電粒子、異方導電性接着フィルム及び接続構造体の作製、並びに、絶縁被覆導電粒子及び接続構造体の評価を行った。結果を表3-2及び表9-3に示す。
実施例1の(工程a~f)によって得た粒子D13.65gの代わりに、下記の工程j~nを経て、表4に記載の導電粒子を得た。この導電粒子を用いたこと以外は実施例1と同様にして、絶縁被覆導電粒子、異方導電性接着フィルム及び接続構造体の作製、並びに、絶縁被覆導電粒子及び接続構造体の評価を行った。結果を表4及び表9-3に示す。
(工程j)前処理工程
平均粒径3.0μmの架橋ポリスチレン粒子(株式会社日本触媒製、商品名「ソリオスター」)6gを、パラジウム触媒(アトテックジャパン株式会社製、商品名「アトテックネオガント834」)を8質量%含有するパラジウム触媒化液100mLに添加し、30℃で30分間攪拌した。次に、φ3μmのメンブレンフィルタ(メルクミリポア社製)を用いた濾過により、樹脂粒子を取り出した。その後、pH6.0に調整された0.5質量%ジメチルアミンボラン液に取り出された樹脂粒子を添加し、表面が活性化された樹脂粒子を得た。そして、60mLの蒸留水に、表面が活性化された樹脂粒子を浸漬した後、超音波分散することで、樹脂粒子分散液を得た。
工程jで得た樹脂粒子分散液を、80℃に加温した水3000mLで希釈した後、めっき安定剤として1g/Lの硝酸ビスマス水溶液を3mL添加した。次に、樹脂粒子を6g含む分散液に、実施例1でも用いた第1層形成用無電解ニッケルめっき液240mLを5mL/分の滴下速度で滴下した。滴下終了後、10分間経過した後に、めっき液を加えた分散液を濾過した。濾過物を水で洗浄した後、80℃の真空乾燥機で乾燥した。このようにして、表4に示す80nmの膜厚のニッケル-リン合金被膜からなる第1層を形成した。第1層を形成することにより得た粒子Eは12gであった。
下記組成の無電解パラジウムめっき液1Lに、第1層を形成した粒子E(12g)を浸漬した。これにより、当該粒子Eの表面上にパラジウム粒子(パラジウムめっき析出核)が形成された粒子Fを得た。反応時間10分、温度60℃にて処理を行った。パラジウム粒子形成用の無電解パラジウムめっき液の組成は以下の通りである。
塩化パラジウム・・・・0.07g/L
エチレンジアミン・・・0.05g/L
ギ酸ナトリウム・・・・0.2g/L
酒石酸・・・・・・・・0.11g/L
pH・・・・・・・・・7
工程lで得た粒子F(12g)を、水洗及び濾過した後、70℃に加温した水3000mLに分散させた。この分散液に、めっき安定剤として1g/Lの硝酸ビスマス水溶液を3mL添加した。次いで、下記組成の析出核形成用無電解ニッケルめっき液60mLを15mL/分の滴下速度で滴下した。滴下終了後、10分間経過した後に、めっき液を加えた分散液を濾過した。濾過物を水で洗浄した後、80℃の真空乾燥機で乾燥した。このようにして、56nmの平均長さのニッケル-リン合金からなる無電解ニッケルめっき析出核を形成した。無電解ニッケルめっき析出核を形成することにより得た粒子Gは13.5gであった。析出核形成用無電解ニッケルめっき液の組成は以下の通りである。
硫酸ニッケル・・・・・・・・・・・・400g/L
次亜リン酸ナトリウム・・・・・・・・150g/L
酒石酸ナトリウム・2水和物・・・・・120g/L
硝酸ビスマス水溶液(1g/L)・・・1mL/L
工程mで得た粒子G(13.5g)を、水洗及び濾過した後、70℃に加温した水1000mLに分散させた。この分散液に、めっき安定剤として1g/Lの硝酸ビスマス水溶液を3mL添加した。次いで、下記組成の第2層形成用無電解ニッケルめっき液60mLを15mL/分の滴下速度で滴下した。滴下終了後、10分間経過した後に、めっき液を加えた分散液を濾過した。濾過物を水で洗浄した後、80℃の真空乾燥機で乾燥した。このようにして、表4に示す20nmの膜厚のニッケル-リン合金被膜からなる第2層を形成した。第2層を形成することにより得た粒子Hは、15.0gであった。第2層形成用無電解ニッケルめっき液の組成は以下の通りである。
硫酸ニッケル・・・・・・・・・・・・400g/L
次亜リン酸ナトリウム・・・・・・・・150g/L
酒石酸ナトリウム・2水和物・・・・・120g/L
硝酸ビスマス水溶液(1g/L)・・・1mL/L
実施例1の第2絶縁粒子を用いず、実施例1の第1絶縁粒子のみを用いたこと以外は実施例1と同様にして、導電粒子、絶縁被覆導電粒子、異方導電性接着フィルム及び接続構造体の作製、並びに、絶縁被覆導電粒子及び接続構造体の評価を行った。結果を表5-1及び表10-1に示す。図17に、絶縁粒子を被覆した後の導電粒子をSEM装置により観察した結果を示す。
実施例1の第1絶縁粒子を用いずに、実施例1の第2絶縁粒子のみを用いたこと以外は実施例1と同様にして、導電粒子、絶縁被覆導電粒子、異方導電性接着フィルム及び接続構造体の作製、並びに、絶縁被覆導電粒子及び接続構造体の評価を行った。結果を表5-1及び表10-1に示す。
第1絶縁粒子として、表6に示される平均粒径145nmの絶縁粒子(絶縁粒子No.4)を用いたこと以外は実施例1と同様にして、導電粒子、絶縁被覆導電粒子、異方導電性接着フィルム及び接続構造体の作製、並びに、絶縁被覆導電粒子及び接続構造体の評価を行った。結果を表5-1及び表10-1に示す。
第2絶縁粒子として、表7-1に示される平均粒径25nmの気相法親水性球状シリカ粉末からなる絶縁粒子(シリカ粒子No.1)を用いたこと以外は実施例1と同様にして、導電粒子、絶縁被覆導電粒子、異方導電性接着フィルム及び接続構造体の作製、並びに、絶縁被覆導電粒子及び接続構造体の評価を行った。結果を表5-2及び表10-2に示す。
第2絶縁粒子として、表7-2に示される平均粒径150nmの気相法親水性球状シリカ粉末からなる絶縁粒子(シリカ粒子No.7)を用いたこと以外は実施例1と同様にして、導電粒子、絶縁被覆導電粒子、異方導電性接着フィルム及び接続構造体の作製、並びに、絶縁被覆導電粒子及び接続構造体の評価を行った。結果を表5-2及び表10-2に示す。
第2絶縁粒子として、表6に示される平均粒径100nmの絶縁粒子(絶縁粒子No.5)を用いた。平均粒径100nmの絶縁粒子は、シリコーンオリゴマーで処理されたものを用いた。上記絶縁粒子を用いたこと以外は実施例1と同様にして、導電粒子、絶縁被覆導電粒子、異方導電性接着フィルム及び接続構造体の作製、並びに、絶縁被覆導電粒子及び接続構造体の評価を行った。結果を表5-2及び表10-2に示す。比較例6は、特許文献6の導電粒子に対応する。
Claims (14)
- 導電粒子と、
前記導電粒子の表面に付着された複数の絶縁粒子と、を備え、
前記導電粒子の平均粒径は、1μm以上10μm以下であり、
前記絶縁粒子は、
200nm以上500nm以下の平均粒径を有する第1絶縁粒子と、
30nm以上130nm以下の平均粒径を有し、シリカからなる第2絶縁粒子と、を含む、
絶縁被覆導電粒子。 - 前記第1絶縁粒子のガラス転移温度は、100℃以上200℃以下である、請求項1に記載の絶縁被覆導電粒子。
- 前記第1絶縁粒子と、前記第2絶縁粒子とによる前記導電粒子の被覆率は、前記導電粒子の総表面積に対して35%以上80%以下である、請求項1又は2に記載の絶縁被覆導電粒子。
- 前記導電粒子は、その前記表面に突起を有する、請求項1~3のいずれか一項に記載の絶縁被覆導電粒子。
- 前記第2絶縁粒子の表面は、疎水化処理剤により被覆されている、請求項1~4のいずれか一項に記載の絶縁被覆導電粒子。
- 前記疎水化処理剤は、シラザン系疎水化処理剤、シロキサン系疎水化処理剤、シラン系疎水化処理剤、及びチタネート系疎水化処理剤からなる群より選ばれる、請求項5に記載の絶縁被覆導電粒子。
- 前記疎水化処理剤は、ヘキサメチレンジシラザン、ポリジメチルシロキサン、及びN,N-ジメチルアミノトリメチルシランからなる群より選ばれる、請求項6に記載の絶縁被覆導電粒子。
- メタノール滴定法による前記第2絶縁粒子の疎水化度は、30%以上である、請求項5~7のいずれか一項に記載の絶縁被覆導電粒子。
- 前記導電粒子は、樹脂粒子と、前記樹脂粒子を覆う金属層とを有し、
前記金属層は、ニッケルを含有する第1層を有する、請求項1~8のいずれか一項に記載の絶縁被覆導電粒子。 - 前記金属層は、前記第1層上に設けられる第2層を有し、
前記第2層は、貴金属及びコバルトからなる群より選ばれる金属を含有する、請求項9に記載の絶縁被覆導電粒子。 - 請求項1~10のいずれか一項に記載の絶縁被覆導電粒子と、
前記絶縁被覆導電粒子が分散された接着剤と、
を備える異方導電性接着剤。 - 前記接着剤がフィルム状である、請求項11に記載の異方導電性接着剤。
- 第1回路電極を有する第1回路部材と、
前記第1回路部材に対向し、第2回路電極を有する第2回路部材と、
前記第1回路部材及び前記第2回路部材を接着する、請求項11又は12に記載の異方導電性接着剤と、
を備え、
前記第1回路電極と前記第2回路電極とは、互いに対向すると共に、前記異方導電性接着剤によって互いに電気的に接続される、
接続構造体。 - 第1回路電極を有する第1回路部材と、
前記第1回路部材に対向し、第2回路電極を有する第2回路部材と、
前記第1回路部材と前記第2回路部材との間に配置された接続部と、
を備え、
前記接続部には、請求項1~10のいずれか一項に記載の絶縁被覆導電粒子が分散しており、
前記第1回路電極と前記第2回路電極とは、互いに対向すると共に、変形した状態の前記絶縁被覆導電粒子を介して互いに電気的に接続される、
接続構造体。
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KR102649185B1 (ko) | 2024-03-18 |
CN113345624B (zh) | 2023-05-12 |
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JPWO2017138483A1 (ja) | 2018-12-20 |
TW201803960A (zh) | 2018-02-01 |
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JP6798509B2 (ja) | 2020-12-09 |
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