JP6079425B2 - Conductive particles, anisotropic conductive adhesive film, and connection structure - Google Patents

Description

  The present invention relates to conductive particles, an anisotropic conductive adhesive film, and a connection structure.

  Conventionally, when electrically connecting circuit members or IC chips or electronic components and circuit members, an adhesive or an anisotropic conductive adhesive in which conductive particles are dispersed has been used. Such a connection form is remarkable in the liquid crystal field. The method of mounting the liquid crystal driving IC on the glass panel for liquid crystal display can be roughly divided into two types, COG (Chip-on-Glass) mounting and COF (Chip-on-Flex) mounting. In COG mounting, a liquid crystal IC is directly bonded onto a glass panel using an anisotropic conductive adhesive containing conductive particles. On the other hand, in COF mounting, a liquid crystal driving IC is bonded to a flexible tape having metal wiring, and they are bonded to a glass panel using an anisotropic conductive adhesive containing conductive particles. As used herein, anisotropic conduction means that circuit electrodes in the pressurizing direction are electrically connected to each other and circuit electrodes in the non-pressurizing direction are electrically insulated from each other. As the conductive particles, particles having nickel plating, nickel plating and gold plating, and nickel plating and palladium plating on the outside of the plastic particles are used. In recent years, there are also conductive particles having protrusions on the nickel plating surface in order to improve electrical conductivity. As a method for forming the protrusion, as disclosed in Patent Document 1, a method is known in which nickel particles are used as a core material and nickel plating is performed thereon. Further, as disclosed in Patent Document 2, a method of forming a rough shape on the particle surface using abnormal deposition of plating is known.

With the recent high definition of liquid crystal display, gold bumps, which are circuit electrodes of a liquid crystal driving IC, have been narrowed in pitch and area. For this reason, there is a problem that the conductive particles of the anisotropic conductive adhesive flow out between adjacent circuit electrodes and cause a short circuit, and this tendency is particularly remarkable in COG mounting. On the other hand, when conductive particles flow out between adjacent circuit electrodes, the number of conductive particles in the anisotropic conductive adhesive trapped between the gold bump and the glass panel decreases, and the connection resistance between the opposing circuit electrodes is reduced. There was a problem of rising and causing poor connection. In particular, in recent years, with the narrowing of pitch and area of gold bumps, 20,000 particles / mm ² or more of conductive particles are introduced per unit area, and this tendency is remarkable.

  Therefore, as a method for solving these problems, a method for preventing deterioration in bonding quality in COG mounting or COF mounting by forming an insulating adhesive on at least one surface of the anisotropic conductive adhesive (Patent Document 3). In addition, there is a method (Patent Document 4) in which the entire surface of the conductive particles is covered with an insulating film.

JP 2007-324138 A JP 2000-243132 A JP-A-8-279371 Japanese Patent No. 2779409

However, in the method of forming an insulating adhesive on one side of the anisotropic conductive adhesive, if the bump area is less than 3000 μm ² , the conductive particles may be increased to obtain a stable connection resistance, There is still room for improvement in insulation between adjacent circuit electrodes. Furthermore, in the circuit member obtained by the method of covering the entire surface of the conductive particles with an insulating film, the insulation between the circuit electrodes in the non-pressurization direction is high, but the conductivity between the circuit electrodes in the pressurization direction is low. There was a problem that it was easy to become.

  Further, when the bump area is small, there is a problem that the conductive particles are not sufficiently left on the bumps due to the resin flow at the time of pressure bonding even though the conductive particles in the anisotropic conductive adhesive are increased. From such problems, it has been important from the viewpoint of both conduction and insulation to suppress the movement of the conductive particles when the anisotropic conductive adhesive is pressure-bonded.

  In the circuit member using the conductive particles obtained by coating the surface of the mother particles with the insulating child particles, the balance between the initial insulation and the conductivity is good. However, it can be seen that the insulating child particles are not compatible with magnetic metal particles such as nickel and tend to rapidly promote the magnetic aggregation of the mother particles when the particle diameter of the mother particles is smaller than 3 μm. It was. In particular, in recent years, in order to cope with the narrow pitch of gold bumps, there is a tendency to reduce the diameter of the conductive particles and increase the diameter of the insulator particles. There has been a problem that it becomes difficult to adsorb on the surface of the mother particles.

  The present invention has been made in view of the above circumstances, and is obtained by using conductive particles capable of achieving both insulating properties and conductivity even when mother particles having a small particle diameter are used, and the same. An object is to provide an anisotropic conductive adhesive film and a connection structure.

The present invention provides a conductive core comprising a plastic core, a mother particle having a plating layer covering the surface of the plastic core and having at least a nickel / phosphorus alloy layer, and an insulator particle covering the surface of the mother particle. A particle diameter of the mother particle is 2.0 μm or more and 3.0 μm or less, a saturation magnetization of the mother particle is 45 emu / cm ³ or less, and a particle diameter of the insulator particle is 180 nm or more and 500 nm. Provided are conductive particles which are:

  A circuit member using such conductive particles has excellent insulating properties and electrical conductivity even when mother particles having a small particle size are used.

  The mother particles may have protrusions on the surface, and the height of the protrusions may be smaller than the particle diameter of the insulator particles.

  The protrusion may be formed by covering the surface of the plastic core body to which the core material is attached with the plating layer, and the core material may be a non-magnetic material.

  When the core material is a non-magnetic material, magnetic aggregation of the mother particles is reduced, and the insulator particles can be coated more uniformly on the mother particles.

  1.0 mass% or more and 10.0 mass% or less may be sufficient as the phosphorus content rate of the said nickel / phosphorus alloy layer.

  By using such conductive particles, the circuit member has better electrical conductivity, suppresses the aggregation of the mother particles, and reduces the coating variation (CV) on the surface of the mother particles of the insulator particles. It becomes possible to do.

  The coverage of the insulator particles may be in the range of 20 to 50%, and the coating variation (CV) may be 0.3 or less.

  The insulator particles may have a layer made of a polymer or oligomer having a weight average molecular weight of 1000 or more.

  By coating the insulator particles with the polymer or oligomer, the dispersibility of the mother particles in the dispersion medium can be improved when the mother particles are coated with the insulator particles.

  The mother particle may further have a layer made of a polymer or oligomer having a weight average molecular weight of 1000 or more. The particle diameter of the insulator particles may be 200 nm or more and 400 nm or less.

  The present invention also provides an anisotropic conductive adhesive film in which the conductive particles are dispersed in an adhesive.

  The present invention also includes a first circuit member having a first circuit electrode formed on the main surface of the first circuit board, and a second circuit electrode formed on the main surface of the second circuit board. The second circuit member is provided between the main surface of the first circuit board and the main surface of the second circuit board, and the first circuit electrode and the second circuit electrode are arranged to face each other. A circuit connection member that connects the first and second circuit members in a state where the first and second circuit members are connected to each other, wherein the circuit connection member is formed by curing the anisotropic conductive adhesive film. Provided is a circuit member connection structure in which the first circuit electrode and the second circuit electrode facing each other are electrically connected through flat conductive particles.

  According to the present invention, even when mother particles having a small particle diameter are used, the insulator particles can be uniformly coated on the mother particles, and the conductive particles having excellent insulation and conductivity, and An anisotropic conductive adhesive film and a connection structure obtained by using this can be provided.

FIG. 1 is a schematic cross-sectional view showing conductive particles according to an embodiment of the present invention. FIG. 2A is a schematic cross-sectional view of an anisotropic conductive adhesive including conductive particles according to an embodiment of the present invention, and FIG. 2B is an embodiment of the present invention of FIG. It is an expanded sectional view of a conductive particle content layer provided with the following conductive particles. FIG. 3A and FIG. 3B are schematic cross-sectional views for explaining a method for manufacturing a connection structure using an anisotropic conductive adhesive.

  Hereinafter, preferred embodiments will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In addition, the drawings are exaggerated for easy understanding, and the dimensional ratios do not necessarily match those described.

(Conductive particles)
FIG. 1 is a schematic cross-sectional view showing the conductive particles of the present embodiment. The conductive particle 30 in the present embodiment includes a base particle 2 and an insulator particle 1 that covers the surface of the base particle 2.

(Mother particles)
In FIG. 1, the mother particle 2 includes a plastic core 21 and a plating layer 22 that covers the surface of the plastic core 21 and has at least a nickel / phosphorus alloy layer. The particle diameter of the mother particle 2 may be smaller than the minimum interval between the circuit electrodes adjacent in the non-pressurizing direction, and when the height of the circuit electrode varies, the particle diameter of the mother particle 2 varies with the above height. May be larger. From such a viewpoint, the particle diameter of the mother particle 2 is specifically 2.0 μm or more and 3.0 μm or less, and may be 2.2 μm or more and 3.0 μm or less, and may be 2.4 μm or more and 3.0 μm. Or 2.5 μm or more and 3.0 μm or less. When the particle diameter of the mother particle 2 is 2.0 μm or more, variation in the height of the circuit electrode can be absorbed, and thus there is a tendency that the conduction reliability is not impaired. Moreover, when the particle diameter of the mother particle 2 is 3.0 μm or less, the insulation reliability tends not to be impaired.

  In addition, the particle diameter of the mother particle 2 indicates the total of the plastic core 21 and the plating layer 22 and does not include the insulator particles 1 and the protrusions 23a. The particle diameter of the mother particle 2 is obtained by photographing about 100 mother particles 2 with a scanning electron microscope (SEM) at a magnification of several thousand to several tens of thousands times, then measuring the particle diameter by image analysis, and deriving from the average value. Shall be. HITACHI S-4800 (manufactured by Hitachi High-Tech Co., Ltd.) was used for the measurement of the particle diameter of the mother particle 2.

The mother particle 2 has a saturation magnetization of 45 emu / cm ³ (4.5 × 10 ⁴ A / m) or less. Saturation magnetization of the mother particles 2, may also be 30 emu / cm ³ or less, may also be 10 emu / cm ³ or less, or may be 5 emu / cm ³ or less. When the saturation magnetization of a mother particle having a particle diameter of 3 μm or less is 45 emu / cm ³ or less, magnetic aggregation of the mother particle hardly occurs, and this tends to easily coat the insulator particles later. The lower the saturation magnetization of the mother particles, the less likely magnetic aggregation will occur. The lower limit of the saturation magnetization of the mother particle 2 is not particularly limited. For example, the saturation magnetization of the mother particle 2 may be 0.5 emu / cm ³ (5.0 × 10 ² A / m) or more.

(Plastic core)
The plastic core 21 of the present embodiment is not particularly limited, but is made of an acrylic resin such as polymethyl methacrylate or polymethyl acrylate, or a polyolefin resin such as polyethylene, polypropylene, polyisobutylene, or polybutadiene. The particle size of the plastic core 21 may be 2.0 to 2.9 μm.

(Plating layer)
The conductor contained in the plating layer is not particularly limited, but gold, silver, copper, platinum, zinc, iron, palladium, nickel, tin, chromium, titanium, aluminum, cobalt, germanium, cadmium, and other metals, and ITO Examples thereof include (indium tin oxide) and metal compounds such as solder. Among these, the metal covered by plating may be nickel, palladium, or gold from the viewpoint of corrosion resistance.

  The plating layer 22 may have a single layer structure or may have a laminated structure (multi-layer structure) composed of a plurality of layers. When the plating layer 22 has a single layer structure, the plating layer 22 is a nickel / phosphorus alloy layer from the viewpoints of cost, conductivity, and corrosion resistance. When the plating layer 22 has a multilayer structure, the plating layer 22 includes a nickel / phosphorus alloy layer and one or more layers different from the nickel / phosphorus alloy layer. For example, the plating layer 22 may have a nickel / phosphorus alloy layer and another layer made of a noble metal such as gold and palladium located outside the nickel / phosphorus alloy layer. In the present embodiment, the nickel / phosphorus alloy layer means an alloy layer containing nickel and phosphorus.

  Regarding the control of magnetism, the nickel / phosphorus alloy layer may contain a metal different from nickel. When the nickel / phosphorus alloy layer contains several percent by mass of a dissimilar metal, for example, a metal with low ion migration such as palladium, conduction deterioration can be suppressed.

  The mother particle 2 may have a functional group on the surface. The functional group which the mother particle 2 has on the surface is used for adsorbing the insulator particles 1 described later to the mother particle 2. Examples of the functional group include a hydroxyl group, a carboxyl group, an alkoxyl group, and an alkoxy group from the viewpoint of forming a bond with a functional group that the insulator particles 1 have on the surface, such as a hydroxyl group, or a functional group of a silicone oligomer with a functional group described later. A carbonyl group etc. are mentioned. Examples of the bond by the functional group that the mother particle 2 and the insulator particle 1 have on the surface include a covalent bond by dehydration condensation and a hydrogen bond.

  When the mother particle 2 has a gold or palladium layer on the surface, it is a compound having any of a mercapto group, sulfide group, and disulfide group that forms a coordinate bond with gold or palladium. A functional group such as a hydroxyl group, a carboxyl group, an alkoxyl group, and an alkoxycarbonyl group may be formed. Examples of the compound include mercaptoacetic acid, 2-mercaptoethanol, methyl mercaptoacetate, mercaptosuccinic acid, thioglycerin, and cysteine.

  When the mother particle 2 has a nickel / phosphorus alloy layer on its surface, it is a compound having a silanol group or a hydroxyl group or a nitrogen compound that forms a strong bond with nickel, and a hydroxyl group, a carboxyl group, an alkoxyl on the surface of the mother particle 2 A group and a functional group such as an alkoxycarbonyl group may be formed. Examples of the compound include carboxybenzotriazole.

  The method of treating the surface of the mother particle 2 with the above compound is not particularly limited, but the above compound such as mercaptoacetic acid or carboxybenzotriazole is contained in an organic dispersion medium such as methanol or ethanol at a concentration of about 10 to 100 mmol / L. A method of dispersing and dispersing the mother particles 2 in the dispersion liquid may be mentioned.

  Examples of the method for forming the plating layer 22 include electroless plating, displacement plating, and electroplating. The electroless plating may be performed from the viewpoint of simplicity, cost, and control of the thickness of the plating layer 22. It may be.

  The thickness of the plating layer 22 is not particularly limited, but may be in the range of 0.001 to 1.0 μm, or may be in the range of 0.005 to 0.3 μm. When the thickness of the plating layer 22 is 0.001 μm or more, conduction failure tends to be suppressed, and when the thickness is 1.0 μm or less, cost tends to be suppressed.

  In consideration of the recent flattening of the glass electrode, the mother particle 2 may have a protrusion 23a on the surface. When the mother particle 2 has the protrusions 23a on the surface, conductivity between circuit electrodes in the pressurizing direction tends to be improved. Examples of the method for forming the protrusions 23a on the surface of the mother particle 2 include a method using abnormal deposition of plating and a method using a core material, but the core material is used in that the shape of the protrusions 23a is formed uniformly. It may be a method. The height H of the protrusions may be in the range of 30 nm to 300 nm, or may be in the range of 50 to 200 nm. If the height of the protrusion 23a is 300 nm or less, short-circuiting between circuit electrodes in the non-pressurizing direction is suppressed, and if it is 30 nm or more, the effect of providing the protrusion 23a on the surface of the mother particle 2 can be sufficiently obtained. Tend. The mother particles 2 may have 5 to 60 area% of the surface area covered with protrusions, that is, the protrusion coverage of the mother particles 2 may be 5 to 60 area%. The saturation magnetization of the mother particle can also be controlled by setting the protrusion coverage of the mother particle 2 within the above range.

When a method using the core material 23 is employed as a method for forming the protrusions 23 a on the surface of the base particle 2, the core material 23 is fixed to the plastic core 21 by chemical bonding. Further, a projection 23 a is formed on the surface of the mother particle 2 reflecting the shape of the core material 23 fixed to the plastic core 21. Examples of the core material 23 include ferromagnetic materials such as nickel, and nonmagnetic materials such as silica, a crosslinked resin, gold, and palladium. A nonmagnetic material may be used for the core material 23 because the saturation magnetization of the mother particle 2 is reduced and magnetic aggregation of the mother particle 2 tends to be reduced when the insulator particles are coated. Even if the core material 23 is a ferromagnetic material (for example, nickel), the core material 23 further includes a non-magnetic material (for example, phosphorus) in addition to the ferromagnetic material, thereby reducing the saturation magnetization of the mother particle 2. Is possible. The nickel / phosphorous alloy layer included in the plating layer 22 may have 1.0 mass% or more and 10.0 mass% or less of phosphorus. Here, when the core material 23 is nickel, the above-mentioned ratio (phosphorus content) of phosphorus included in the nickel / phosphorus alloy layer is:
(Ratio of phosphorus in nickel / phosphorus alloy layer) = (total mass of phosphorus) / (total mass of phosphorus + total mass of nickel)
In addition to the nickel / phosphorus alloy layer, the above-mentioned “total mass of phosphorus” and “total mass of nickel” include the mass of atoms derived from the core material 23.

  When the proportion of phosphorus in the nickel / phosphorus alloy layer is 10.0% by mass or less, the plating layer 22 tends to be excellent in conductivity and the conduction resistance during mounting tends to be low. When the ratio of phosphorus is 1.0 mass% or more, the saturation magnetization of the mother particle 2 can be reduced, so that the magnetic aggregation of the mother particle 2 can be reduced, and the coating variation of the insulator particles 1 can be reduced. Tends to decrease. The above-mentioned tendency is remarkable when the particle diameter of the mother particle 2 is 3 μm or less.

  Moreover, the plastic core 21 may 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. Since the plastic core 21 has the functional group on the surface, the core member 23 can be fixed to the plastic core 21. For example, when the plastic core 21 is manufactured, the plastic core 21 having a carboxyl group on the surface can be synthesized by using acrylic acid as a copolymerization monomer. Further, by using glycidyl methacrylate as a copolymerization monomer, the plastic core 21 having a glycidyl group on the surface can be synthesized.

  Further, the mother particle 2 may further include a polymer electrolyte layer provided between the plastic core 21 and the core material 23. In this case, the core material 23 is adsorbed to the plastic core 21 by chemical bonding via the polymer electrolyte layer. For example, the plastic core 21, the polymer electrolyte layer (not shown), and the core material 23 each have a functional group, and the functional group of the polymer electrolyte layer has a function of each of the plastic core 21 and the core material 23. It may be chemically bonded to the group. Chemical bonds include covalent bonds, hydrogen bonds, ionic bonds, and the like.

  The surface potential (zeta potential) of particles having a functional group selected from a hydroxyl group, a carboxyl group, an alkoxy group, a glycidyl group and an alkoxycarbonyl group on the surface is usually negative when the pH is in a neutral region. Further, when the surface potential of the core material 23 is negative, it is often difficult to sufficiently cover the surface of particles having a negative surface potential with particles having a negative surface potential. By providing this, the core material 23 can be efficiently adsorbed to the plastic core.

  As the polymer electrolyte that forms the polymer electrolyte layer, a polymer that is ionized in an aqueous solution and has a functional group having a charge in the main chain or side chain may be used, or a polycation may be used. Polycations generally have a positively charged functional group such as polyamine, such as polyethyleneimine (PEI), polyallylamine hydrochloride (PAH), polydiallyldimethylammonium chloride (PDDA), Polyvinylpyridine (PVP), polylysine, polyacrylamide, and a copolymer containing at least one of them can be used. Among polyelectrolytes, polyethyleneimine has a high charge density and a strong binding force.

  The polyelectrolyte layer includes alkali metal (Li, Na, K, Rb, and Cs) ions, alkaline earth metal (Ca, Sr, Ba, and Ra) ions, and halides to avoid electromigration or corrosion. Ions (fluorine ions, chloride ions, bromine ions, and iodine ions) may not be substantially contained.

  The polymer electrolyte is water-soluble and soluble in a mixed solution of water and an organic solvent. The weight average molecular weight of the polymer electrolyte cannot be determined unconditionally depending on the type of polymer electrolyte used, but may generally be about 500 to 200,000.

  By adjusting the type or molecular weight of the polymer electrolyte, the coverage of the plastic core 21 with the core material 23 can be controlled. Specifically, when a polymer electrolyte having a high charge density such as polyethyleneimine is used, the coverage by the core material 23 tends to be high, and a polymer electrolyte having a low charge density such as polydiallyldimethylammonium chloride is used. In this case, the coverage with the core material 23 tends to be low. Further, when the molecular weight of the polymer electrolyte is large, the coverage by the core material 23 tends to be high, and when the molecular weight of the polymer electrolyte is small, the coverage by the core material 23 tends to be low.

  By dispersing the plastic core 21 having a functional group selected from a hydroxyl group, a carboxyl group, an alkoxy group, a glycidyl group and an alkoxycarbonyl group on the surface, the polymer electrolyte is adsorbed on the surface of the plastic core. Thus, a polymer electrolyte layer can be formed. By providing the polymer electrolyte layer, the core material 23 is adsorbed mainly by electrostatic attraction. 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.

  The excess polymer electrolyte may be removed by rinsing after the plastic core 21 with the polymer electrolyte layer formed is taken out of the polymer electrolyte solution. The rinsing is performed using, for example, water, alcohol, or acetone. Ion exchange water (so-called ultrapure water) having a specific resistance value of 18 MΩ · cm or more may be used. Since the polymer electrolyte adsorbed on the plastic core 21 is electrostatically adsorbed on the surface of the plastic core 21 by chemical bonding, it does not peel off in this rinsing step.

  The polymer electrolyte solution is obtained by dissolving a polymer electrolyte in water or a mixed solvent of water and a water-soluble organic solvent. Examples of water-soluble organic solvents that can be used include methanol, ethanol, propanol, acetone, dimethylformamide, and acetonitrile.

  The concentration of the polymer electrolyte in the polymer electrolyte solution may generally be about 0.01 to 10% by mass. Further, the pH of the polymer electrolyte solution is not particularly limited. When the polymer electrolyte is used at a high concentration, the coverage of the plastic core body by the core material 23 tends to be high. When the polymer electrolyte is used at a low concentration, the coverage of the plastic core body 21 by the core material 23 is high. Tend to be low.

  When the core material 23 is covered by alternate lamination using a polymer electrolyte, since the polymer electrolyte is wound around the core material 23, the bonding force is dramatically improved. From the viewpoint of bonding strength, a polymer electrolyte having a weight average molecular weight of 10,000 or more may be used. The binding force improves with the weight average molecular weight, but if the weight average molecular weight is too high, the plastic cores 21 tend to aggregate.

  Only one layer of the core material 23 may be coated. Multi-layer lamination tends to make it difficult to control the amount of lamination.

  The coverage of the plastic core 21 with the core material 23 may be 5 to 60 area% or 25 to 60 area%. The coverage in this case can be calculated in the same manner as the coverage of the insulator particles 1 described later by analyzing the center of the particle surface (two-dimensional image) (a circle having the radius of the plastic core 21 as a diameter). 80% by area corresponds to the case of close packing. In addition, the said coverage in this embodiment is an average value of the coverage calculated | required from 100 sheets (100 particle | grains) of the SEM photograph of particle | grains.

  When performing electroless plating, the plastic core body on which the core material 23 is adsorbed is dispersed in water with ultrasonic waves. Since the core material 23 is bonded to the surface of the plastic core 21, the core material 23 is less likely to drop off by ultrasonic treatment, which is advantageous. The dropout rate of the core material 23 may be 10% or less or 3% or less when the ultrasonic wave is irradiated for 15 minutes at a resonance frequency of 28 to 38 kHz and an ultrasonic output of 100 W.

(Insulator particles)
The insulator particles 1 coated on the mother particles 2 may be organic fine particles (organic particles), inorganic oxide fine particles (inorganic oxide particles), or organic-inorganic hybrid particles. Organic fine particles have excellent conductivity. On the other hand, inorganic oxide fine particles are excellent in that they are hard, stable against physical impact, and hardly dissolve in a solvent. Examples of the insulator particles coated on the mother particles 2 are shown below.

  Examples of the organic fine particles include particles made of polyolefin resins such as polyethylene, polypropylene, and polybutadiene, acrylic resins such as polymethyl methacrylate, epoxy resins, and polyimide resins.

The inorganic oxide fine particles may be oxide particles containing an element of silicon, aluminum, zirconium, titanium, niobium, zinc, tin, cerium, or magnesium, and these may be used alone or in combination of two or more. Can be used. Further, it may be water-dispersed colloidal silica (SiO ₂ ) having excellent insulating properties and controlled particle diameter. Examples of such commercially available inorganic oxide fine particles include Snowtex, Snowtex UP (manufactured by Nissan Chemical Industries, Ltd.), and Quatron PL series (manufactured by Fuso Chemical Industries, Ltd.). In terms of insulation reliability, the concentration of alkali metal ions and alkaline earth metal ions in the dispersion solution may be 100 ppm or less, and the inorganic oxide fine particles are produced by hydrolysis reaction of metal alkoxide, so-called sol-gel method. Also good.

  Typical organic-inorganic hybrid particles are particles obtained by copolymerization of an acrylic resin and a polyfunctional alkoxysilane. When the proportion of alkoxysilane is increased, the properties of inorganic particles are exhibited, and when the proportion of acrylic resin is increased, the properties of organic particles are exhibited. Synthetic methods are represented by dispersion polymerization and precipitation polymerization.

  The insulator particles 1 may have a functional group on the surface of the mother particle 2 such as a hydroxyl group, a silanol group, and a carboxyl group on the outside, or a functional group that has good reactivity with the polymer electrolyte described later.

  The particle diameter of the insulator particles 1 measured by the specific surface area conversion method by the BET method or the X-ray small angle scattering method is 180 nm or more and 500 nm or less, may be 200 nm to 480 nm, or may be 200 nm to 400 nm. It may be 250 nm to 400 nm. When the particle diameter of the insulator particles 1 is 200 nm or more, the insulator particles adsorbed on the conductive particles 30 act as an insulating film and tend to suppress the occurrence of a short circuit. On the other hand, when the particle diameter of the insulator particles 1 is 500 nm or less, sufficient conductivity in the pressurizing direction of connection tends to be obtained.

  The particle diameter of the insulator particles 1 may be larger than the height H of the protrusion 23a.

  Examples of the method of coating the insulator particles 1 on the mother particles 2 include a method of adsorbing the insulator particles 1 having a functional group on the surface to the mother particles 2 having a functional group on the surface.

  The surface potential (zeta potential) of the mother particle 2 having a functional group such as a hydroxyl group, a carboxyl group, an alkoxyl group, and an alkoxycarbonyl group is usually negative (if the pH is neutral). On the other hand, the surface potential of the insulator particles 1 having a functional group such as a hydroxyl group is usually negative. It is difficult to coat particles having a negative surface potential around particles having a negative surface potential.

  In such a case, the method of coating the insulator particles 1 on the mother particles 2 may be a method of alternately laminating the polymer or oligomer and the insulator particles 1, and the polymer electrolyte and the insulator particles 1 are alternately arranged. A lamination method may be used. The coating method includes (1) a step of dispersing the mother particles 2 having functional groups on the surface in a polymer electrolyte solution, adsorbing the polymer electrolyte on the surfaces of the mother particles 2, and then rinsing; There is a step of rinsing after dispersing the particles 2 in the dispersion solution of the insulator particles 1 and adsorbing the insulator particles 1 on the surfaces of the mother particles 2. As shown in FIG. 2B, according to the above coating method, fine particles having an insulating coating layer 3 formed by stacking a polymer electrolyte and the insulator particles 1 on the surface can be produced.

  Such a method is called an alternating lamination method (Layer-by-Layer assembly). The alternate lamination method is described in G.H. This is a method of forming an organic thin film published in 1992 by Decher et al. (Thin Solid Films, 210/211, p831 (1992)). In this method, a polycation adsorbed on a substrate by electrostatic attraction by alternately immersing the substrate in an aqueous solution of a polymer electrolyte having a positive charge (polycation) and a polymer electrolyte having a negative charge (polyanion). And a combination of polyanions are laminated to obtain a composite film (alternate laminated film).

  In the alternating layering method, the film is grown by attracting the charge of the material formed on the substrate and the material having the opposite charge in the solution by electrostatic attraction, so that the adsorption proceeds and the charge is neutralized. When this occurs, no further adsorption occurs. Therefore, when reaching a certain saturation point, the film thickness does not increase any more. Lvov et al. Reported on a method of applying the alternating lamination method to fine particles, and 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), p. 6195-6203). By using this method, insulating particles having a negative surface charge and polydiallyldimethylammonium chloride (PDDA) or polyethylenimine (PEI), which are polycations having the opposite charge, are alternately laminated to provide insulation. It is possible to form a fine-particle laminated thin film in which neutron particles and polymer electrolyte are alternately laminated.

  After immersing the mother particles in the polymer electrolyte solution or the dispersion of insulator particles, and before immersing in the insulator particle dispersion or polymer electrolyte solution having the opposite charge, the excess polymer electrolyte solution or The insulator particle dispersion may be washed away. Examples of such rinsing include water, alcohol, and acetone.

  The polymer electrolyte solution is obtained by dissolving a polymer electrolyte in water or a mixed solvent of an organic solvent. Examples of the water-soluble organic solvent that can be used include methanol, ethanol, propanol, acetone, dimethylformamide, and acetonitrile.

  The polymer electrolyte may be a polymer that ionizes in an aqueous solution and has a functional group having a charge in the main chain or side chain, or may be a polycation. The polycation generally has a functional group capable of being positively charged (having a positive charge), such as polyamines, such as polyethyleneimine (PEI), polyallylamine hydrochloride (PAH), Polydiallyldimethylammonium chloride (PDDA), polyvinylpyridine (PVP), polylysine, polyacrylamide, and a copolymer containing at least one of them can be used.

  Among polyelectrolytes, polyethyleneimine has a high charge density and a strong binding force. Among these polymer electrolytes, alkali metal (Li, Na, K, Rb, and Cs) ions, alkaline earth metal (Ca, Sr, Ba, and Ra) ions, and in order to avoid electromigration and corrosion, and Halide ions (fluoride ions, chloride ions, bromide ions, and iodide ions) may not be included.

  These polymer electrolytes are both soluble in water or soluble in organic solvents such as alcohol, and the weight average molecular weight of the polymer electrolyte is not generally determined by the type of polymer electrolyte used. Generally, it may be 1000 or more, and may be about 1000-200000. If the weight average molecular weight is 1000 or more, the dispersibility of the mother particles 2 in the polymer electrolyte solution tends to be sufficient, and even if the particle diameter of the mother particles 2 is 3.0 μm or less, the aggregation becomes obvious. There is a tendency to suppress. The concentration of the polymer electrolyte in the solution may generally be about 0.01 to 10% by mass. Further, the pH of the polymer electrolyte solution is not particularly limited.

  By using the polymer electrolyte thin film obtained in this way, the polymer electrolyte can be uniformly coated on the surface of the mother particle 2 without defects, and the insulating property is maintained even when the circuit electrode spacing in the non-pressurizing direction is narrow. The connection resistance is low and good between the circuit electrodes in the pressurizing direction that are secured and electrically connected.

  When the particle diameter of the mother particle 2 is small, the magnetic aggregation of the mother particle 2 increases, and it becomes difficult to adsorb the insulator particles 1 on the surface of the mother particle 2. In that case, when a polymer having a weight average molecular weight of 1000 or more is arranged on the surface of the base particle 2, the dispersion of the base particle 2 in the insulator particle dispersion is promoted, and the surface of the insulator particle 1 on the surface of the mother particle 2 is promoted. Adsorption tends to be easy.

  Further, by adjusting the type, molecular weight, or concentration of the polymer electrolyte, it is possible to control the coverage of the insulator particles 1 that are further coated on the surfaces of the mother particles 2 after the coating of the polymer electrolyte.

  Specifically, when a polymer electrolyte thin film having a high charge density such as polyethyleneimine is used, the coverage of the insulator particles 1 tends to be high, and a polymer electrolyte thin film having a low charge density such as polydiallyldimethylammonium chloride. When is used, the coverage of the insulator particles 1 tends to be low. Further, when the molecular weight of the polymer electrolyte is large, the coverage of the insulator particles 1 tends to be high, and when the molecular weight of the polymer electrolyte is small, the coverage of the insulator particles 1 tends to be low. Furthermore, when the polymer electrolyte solution is used at a high concentration, the coverage of the insulator particles 1 tends to increase, and when the polymer electrolyte solution is used at a low concentration, the coverage of the insulator particles 1 tends to decrease. There is.

  The surface of the insulator particles 1 may be coated with a polymer or oligomer having a weight average molecular weight of 500 or more, and the weight average molecular weight may be 1000 or more, 1000 to 10,000, or 1000 to 4000. There may be. The surface of the insulator particles 1 may be coated with a functionalized silicone oligomer having a weight average molecular weight of 1000 to 4000. The polymer or oligomer may have a functional group. The functional group may be a functional group on the surface of the mother particle or a group capable of reacting with the above-described polyelectrolyte, specifically a glycidyl group, a carboxyl group or an isocyanate group, It may be a glycidyl group.

  In this way, by bonding particles having a chemically reactive polymer or oligomer to each other, it is possible to obtain unprecedented strong bonding, and to cope with a decrease in the diameter of the mother particle 2 or an increase in the diameter of the insulator particle 1. it can.

  The coverage of the insulator particles 1 may be in the range of 10 area% to 50 area%, or in the range of 20 to 50 area%. When the coverage of the insulator particles 1 is high, the insulation tends to be high and the conductivity is low, and when the coverage of the insulator particles 1 is low, the conductivity tends to be high and the insulation is low. In addition, the coverage here is the total surface area of the central part (circle having the radius of the plastic core 21 as a diameter) on the surface of the mother particle 2 (area not including protrusions calculated from the particle diameter of the mother particle). , P / W × 100, where P is the surface area of the portion analyzed to be covered with the insulator particles 1 by image analysis of the central portion of the particle (circle having the radius of the plastic core 21 as a diameter). (Area%). In addition, the surface area P of the portion analyzed to be covered in the present embodiment is an average value of the surface areas obtained from 100 SEM photographs of particles.

  Further, the coating variation (CV) of the insulator particles 1 may be in a range of 0.3 or less. When the coating variation (CV) of the insulator particles 1 is 0.3 or less, the insulation tends to be improved. Note that the coating variation (CV) here is the standard deviation of the coverage calculated based on the image analysis of the center of the particle (the circle having the diameter of the plastic core 21 as a diameter) as S, When the average value is M, it is represented by S / M × 100 (%). In addition, the standard deviation S and the average value M of the coverage in the present embodiment are obtained from 100 SEM photographs of particles.

  The mother particle 2 is preferably covered with only one insulator particle 1. When multiple layers are laminated, it may be difficult to control the amount of lamination.

  Bonding between the insulator particles 1 and the mother particles 2 can be strengthened by heating and drying the conductive particles 30 thus obtained, that is, the mother particles 2 coated with the insulator particles 1. The reason why the bonding force increases is the chemical bonding between functional groups. The temperature for heat drying may be 60 to 200 ° C., and the heating time may be in the range of 10 to 180 minutes. When the heating temperature is 60 ° C. or higher, or when the heating time is 10 minutes or longer, peeling of the insulator particles 1 from the mother particles 2 tends to be suppressed, and the heating temperature is 200 ° C. or lower or When the heating time is 180 minutes or less, the deformation of the conductive particles 30 tends to be suppressed.

  The surface of the conductive particles 30 may be further subjected to silicone oligomer treatment. When the surface of the conductive particles 30 is treated with the silicone oligomer, the insulation reliability of the conductive particles 30 tends to be further improved. The silicone oligomer used here may have a hydrophobic functional group such as a methyl group or a phenyl group and have a weight average molecular weight of about 500 to 5,000.

(Anisotropic conductive adhesive)
By dispersing the conductive particles 30 produced as described above in the adhesive 31, the conductive particle-containing layer 32 is obtained. The anisotropic conductive adhesive 40 may consist only of the conductive particle-containing layer 32, and has a two-layer structure further including a conductive particle non-containing layer 33 formed on one surface of the conductive particle-containing layer 32. As shown in FIG. 2A, a three-layer structure further including a conductive particle non-containing layer 34 formed on the other surface of the conductive particle-containing layer 32 may be used. Moreover, as shown in FIG. 2B, which is an enlarged cross-sectional view of FIG. 2A, the conductive particles 30 are composed of the base particles 2 and the insulating coating layer 3 formed by the insulator particles 1 on the surface of the base particles 2. Is provided.

  For the adhesive 31 used for the anisotropic conductive adhesive 40, a mixture of a heat-reactive resin and a curing agent is used. As the adhesive, a mixture of an epoxy resin and a latent curing agent may be used. Examples of the latent curing agent include imidazole series, hydrazide series, boron trifluoride-amine complex, sulfonium salt, amine imide, polyamine salt, and dicyandiamide. In addition, for the adhesive, a mixture of a radical reactive resin and an organic peroxide or an energy ray curable resin such as an ultraviolet ray can be used.

  Epoxy resins include bisphenol-type epoxy resins derived from epichlorohydrin and bisphenol A, bisphenol F, bisphenol AD, etc .; epoxy novolac resins derived from epichlorohydrin and phenol novolac or cresol novolac; a skeleton containing a naphthalene ring Naphthalene-based epoxy resin having glycidyl amine, glycidyl amine, glycidyl ether, biphenyl, or various epoxy compounds having two or more glycidyl groups in one molecule; and the like are used alone or in combination of two or more. It is possible.

These epoxy resins may be high-purity products in which impurity ions (Na ⁺ , Cl ⁻ etc.) or hydrolyzable chlorine are reduced to 300 ppm or less in order to prevent electromigration.

  In order to reduce the stress after bonding or to improve the adhesion, the adhesive 31 can be mixed with butadiene rubber, acrylic rubber, styrene-butadiene rubber, silicone rubber, or the like. As the anisotropic conductive adhesive 40, a paste (anisotropic conductive adhesive paste) or a film (anisotropic conductive adhesive film) is used. The adhesive 31 may include a thermoplastic resin (film-forming polymer) such as a phenoxy resin, a polyester resin, and a polyamide resin in order to form a film. These film-forming polymers are also effective for stress relaxation during curing of the heat-reactive resin. In order to improve adhesiveness, the film-forming polymer may have a functional group such as a hydroxyl group.

  Film formation is, for example, liquefied by dissolving or dispersing an adhesive composition composed of a thermally reactive resin such as an epoxy resin, a film-forming polymer such as acrylic rubber, and a latent curing agent in an organic solvent, The liquid adhesive composition is applied on a peelable substrate, and the solvent is removed below the activation temperature of the curing agent. The solvent used at this time may be an aromatic hydrocarbon-based and oxygen-containing mixed solvent in order to improve the solubility of the material.

  The thickness of the anisotropic conductive adhesive film is relatively determined in consideration of the particle diameter of the conductive particles 30 and the characteristics of the anisotropic conductive adhesive 40. In this case, the conductive particle-containing layer 32 and the conductive particles are not contained. A two-layer configuration of the layer 33 may be used. By disposing the conductive particle non-containing layer 33 on the metal bump side and the conductive particle containing layer 32 on the glass side, the conductive particles 30 are captured on the metal bump side with high efficiency. Therefore, the conductive particle containing layer 32 may be thin, and the conductive particle non-containing layer 33 may be thicker and more fluid than the conductive particle containing layer 32. Specifically, the thickness of the conductive particle-containing layer 32 is in the range of 3 to 15 μm, the thickness of the conductive particle-free layer 33 is in the range of 7 to 20 μm, and the thickness of the conductive particle-containing layer 32 is anisotropic conductive adhesion. 50 mass% or less of the thickness of the whole agent film may be sufficient.

  Moreover, the three-layer structure which further arrange | positioned the electroconductive particle non-containing layer 34 with a thickness of 4 micrometers or less on the glass electrode side may be sufficient in the meaning which strengthens adhesiveness with a glass substrate or ITO. The conductive particle non-containing layer 34 may have high fluidity.

  As shown in FIG. 2B, in the conductive particle-containing layer 32, conductive particles 30 and inorganic oxide particles 35 having a hydrophobic surface may be dispersed in the adhesive 31. In the conductive particle-containing layer 32, the conductive particles 30 and the inorganic oxide particles 35 having a hydrophobic surface are dispersed in the adhesive 31, whereby the flow of the conductive particles 30 is suppressed by the inorganic oxide particles 35. Since the particles 30 are easily captured on the metal bumps 42 and the ITO or IZO electrode 44, high conductivity tends to be obtained in the pressing direction.

  An example of a method for producing the connection structure 50 using the anisotropic conductive adhesive 40 will be described with reference to FIGS.

  As shown in FIG. 3A, the connection structure 50 is manufactured by a first circuit electrode (metal bump) 42 on a first circuit board (IC chip) 41 and a second circuit board (glass). A step of electrically connecting a second circuit electrode (ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide) electrode) 44 on the substrate (43) through an anisotropic conductive adhesive 40 is provided. 3A, the anisotropic conductive adhesive 40 has a three-layer structure in which a conductive particle non-containing layer 33, a conductive particle containing layer 32, and a conductive particle non-containing layer 34 are laminated in this order. At this time, the IC chip and the glass substrate are arranged so that the metal bumps 42 and the circuit electrodes 44 on the glass 43 face each other. Next, as shown in FIGS. 3A and 3B, the IC chip and the glass substrate are heated under pressure, and these are laminated via the anisotropic conductive adhesive 40. The obtained connection structure 50 includes a first circuit member in which the first circuit electrode 42 is formed on the main surface of the first circuit board 41, and a second circuit member on the main surface of the second circuit board 43. Are provided between the second circuit member on which the circuit electrode 44 is formed, the main surface of the first circuit board 41 and the main surface of the second circuit board 43, and the first circuit electrode 42 and the second circuit board 43. A circuit connection member 40a for connecting the first and second circuit members to each other in a state where the circuit electrodes 44 are arranged to face each other. Through heating and pressing, the adhesive 31 in the anisotropic conductive adhesive 40 is melted and deformed and then cured. In addition, the conductive particles 30 in the anisotropic conductive adhesive 40 are crushed into flat conductive particles. The circuit connection member 40a is made of a cured product of the anisotropic conductive adhesive 40. For example, when the anisotropic conductive adhesive 40 has a three-layer structure, the cured product 33a of the conductive particle-free layer 33 and the conductive particles are formed. It consists of a cured product 32 a of the containing layer 32 and a cured product 34 a of the conductive particle non-containing layer 34. Opposing first circuit electrode 41 and second circuit electrode 43 are electrically connected via flat conductive particles.

  When the connection structure 50 is produced in this way, the flow of the conductive particles is suppressed by the inorganic oxide particles 35, and the conductive particles are easily captured on the metal bumps 42. Therefore, high conductivity is obtained in the pressurizing direction. . Since the conductive particle non-containing layer 34 having a low content of the inorganic oxide particles 35 is in contact with the metal bump 42 and the ITO or IZO electrode 44, the embedding property and the adhesiveness can be maintained. By improving the capture rate of the conductive particles 30 between the circuit electrodes in the pressurizing direction, the ratio of the conductive particles flowing between the circuit electrodes in the non-pressurizing direction is reduced, so that the insulation between the circuit electrodes in the non-pressurizing direction is improved. . Even if the coverage of the insulating coating layer 3 existing on the surface of the conductive particles 30 is lowered, the insulating property is easily secured. By reducing the coverage of the insulating coating layer 3, the electrical conductivity between the circuit electrodes in the pressing direction is further improved.

(1) Preparation of mother particle 1 10 g of a plastic core body having an average particle diameter of 2.6 μm made of a copolymer of divinylbenzene and acrylic acid having an adjusted degree of crosslinking was prepared. This plastic core has a carboxyl group on its surface. The hardness of the plastic core (compression modulus when the particle diameter was displaced 20% at 200 ° C., 20% K value) was 280 kgf / mm ² .

  A 30% by mass polyethyleneimine aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.) having a molecular weight of 70,000 was diluted to 0.3% by mass with ultrapure water. 10 g of the plastic core was added to 300 mL of this 0.3 mass% polyethyleneimine aqueous solution, and the mixture was stirred at room temperature for 15 minutes. The plastic core was taken out by filtration using a membrane filter (manufactured by Millipore) having a pore diameter of 3 μm, and the taken out plastic core was put in 300 g of ultrapure water and stirred at room temperature for 5 minutes. Next, the plastic core was taken out by filtration using a membrane filter (manufactured by Millipore) having a pore diameter of 3 μm. The plastic core on the membrane filter was washed twice with 200 g of ultrapure water to remove the unadsorbed polyethyleneimine to obtain a plastic core on which polyethyleneimine was adsorbed.

  A colloidal silica dispersion having an average particle diameter of 100 nm was diluted with ultrapure water to obtain a 0.33% by mass silica particle dispersion (total amount of silica: 1 g). The plastic core adsorbed with polyethyleneimine was put therein and stirred at room temperature for 15 minutes. Thereafter, the plastic core was taken out by filtration using a membrane filter (manufactured by Millipore) having a pore diameter of 3 μm. Since no silica was extracted from the filtrate, it was confirmed that substantially all silica particles were adsorbed on the plastic core. The plastic core with the silica particles adsorbed was placed in 200 g of ultrapure water and stirred at room temperature for 5 minutes. Thereafter, the plastic core was removed by filtration using a membrane filter (manufactured by Millipore) having a pore diameter of 3 μm, and the plastic core on the membrane filter was washed twice with 200 g of ultrapure water. The washed plastic nuclei were dried by heating at 80 ° C. for 30 minutes and 120 ° C. for 1 hour in order to obtain plastic nuclei (composite particles) having silica particles adsorbed on the surface.

  1 g of the above composite particles were collected, irradiated with ultrasonic waves having a resonance frequency of 28 kHz and an output of 100 W for 15 minutes, and then palladium containing 8% by mass of Atotech Neogant 834 (trade name, manufactured by Atotech Japan Co., Ltd.), which is a palladium catalyst. The mixture was added to 100 mL of the catalyst solution and stirred at 30 ° C. for 30 minutes while irradiating with ultrasonic waves. Thereafter, the composite particles were taken out by filtration using a membrane filter (manufactured by Millipore) having a pore diameter of 3 μm, and the taken out composite particles were washed with water. The composite particles after washing with water were added to a 0.5% by mass dimethylamine borane solution adjusted to pH 6.0 to obtain composite particles whose surface was activated.

The surface-activated composite particles were immersed in distilled water and ultrasonically dispersed to obtain a suspension. While stirring this suspension at 50 ° C., nickel sulfate hexahydrate 50 g / L, sodium hypophosphite monohydrate 20 g / L, dimethylamine borane 2.5 g / L and citric acid 50 g / L were added. The electroless plating solution A which was mixed and adjusted to pH 5.0 was gradually added to form an electroless nickel / phosphorus alloy layer on the composite particles. The nickel / phosphorus alloy layer contained about 7% by mass of phosphorus. The thickness of nickel was measured by sampling and atomic absorption, and the addition of electroless plating solution A was stopped when the thickness of the nickel plating layer reached 750 mm. After filtration, washing with 100 mL of pure water was performed for 60 seconds to obtain mother particles 1 having protrusions on the surface and having a nickel / phosphorus alloy layer as a plating layer. When the height of the protrusion on the surface of the mother particle 1 was observed with an SEM, it was 100 nm, which was almost the same as the particle size of the silica particles adsorbed on the plastic core. The coverage of the protrusions was measured by image analysis of the SEM image, and was about 40 area%. Further, the saturation magnetization per unit volume of the mother particle 1 was determined in the following manner. For measurement of saturation magnetization, a vibrating sample magnetometer (VSM: Vibrating Sample Magnetometer, BHV-525 manufactured by Riken Denshi) was used. Further, the magnetometer was calibrated in advance using a standard sample (nickel). The mother particles 1 were weighed into a dedicated container and attached to a sample holder. A sample holder was attached to the magnetometer body, and a magnetization curve was obtained by measurement under the conditions of a temperature of 20 ° C. (constant temperature), a maximum applied magnetic field of 20,000 Oe (1.6 MA / m), and a speed of 3 minutes / loop. Saturation magnetization (emu) was determined from the obtained magnetization curve. On the other hand, the specific gravity of the mother particle 1 was measured using a hydrometer (Acpyc 1330 manufactured by Shimadzu Corporation). When the saturation magnetization per unit volume of the mother particle 1 is calculated from the saturation magnetization of the mother particle 1, the mass of the mother particle 1 used for measurement of the saturation magnetization, and the specific gravity of the mother particle 1, it is 0.5 emu / cm ³ . there were.

(2) Preparation of mother particle 2 A protrusion (core) was obtained in the same manner as mother particle 1 except that a nickel fine particle dispersion having an average particle diameter of 100 nm was used instead of a colloidal silica dispersion having an average particle diameter of 100 nm and the input amount was changed. A mother particle 2 having a material (nickel) was produced. As a result of measuring the height and coverage of the projection by image analysis of the SEM image, the height of the projection was 100 nm, the coverage of the projection was about 40 area%, and the saturation magnetization per unit volume was measured. 0.5 emu / cm ³ .

(3) Preparation of mother particles 3 Protrusions (core nickel) are the same as mother particles 2 except that plastic nuclei with an average particle size of 2.8 μm were used instead of plastic nuclei with an average particle size of 2.6 μm. Base particles 3 were produced. As a result of measuring the height and coverage of the protrusions by image analysis of the SEM image, the height of the protrusions was 100 nm and the coverage of the protrusions was about 40 area%. Further, the saturation magnetization per unit volume of the mother particle 3 was measured and found to be 44.3 emu / cm ³ .

(4) Preparation of mother particles 4 Protrusions (core nickel) are the same as mother particles 2 except that plastic nuclei with an average particle size of 2.3 μm were used instead of plastic nuclei with an average particle size of 2.6 μm. Base particles 4 were produced. As a result of measuring the height and coverage of the protrusions by image analysis of the SEM image, the height of the protrusions was 100 nm and the coverage of the protrusions was about 40 area%. Further, the saturation magnetization per unit volume of the mother particles 4 was measured and found to be 44.7 emu / cm ³ .

(5) Preparation of mother particle 5 Similar to mother particle 2 except that a plastic core having an average particle diameter of 2.1 μm was used instead of a plastic core having an average particle diameter of 2.6 μm, it has protrusions (nickel core material). Base particles 5 were produced. As a result of measuring the height and coverage of the protrusions by image analysis of the SEM image, the height of the protrusions was 100 nm and the coverage of the protrusions was about 40 area%. Further, the saturation magnetization per unit volume of the mother particles 5 was measured and found to be 44.8 emu / cm ³ .

(6) Preparation of mother particle 6 Similar to the mother particle 2 except that a plastic core having an average particle diameter of 1.8 μm was used instead of a plastic core having an average particle diameter of 2.6 μm, it has protrusions (nickel core material). Base particles 6 were prepared. As a result of measuring the height and coverage of the protrusions by image analysis of the SEM image, the height of the protrusions was 100 nm and the coverage of the protrusions was about 40 area%. Further, the saturation magnetization per unit volume of the mother particles 6 was measured and found to be 44.9 emu / cm ³ .

(7) Preparation of mother particle 7 Similar to the mother particle 2 except that a plastic core having an average particle diameter of 3.0 μm was used instead of a plastic core having an average particle diameter of 2.6 μm, it has protrusions (nickel core material). Base particles 7 were prepared. As a result of measuring the height and coverage of the protrusions by image analysis of the SEM image, the height of the protrusions was 100 nm and the coverage of the protrusions was about 40 area%. Further, the saturation magnetization per unit volume of the mother particle 7 was measured and found to be 44.5 emu / cm ³ .

(8) Production of mother particles 8 Mother particles 8 having protrusions (core nickel) were produced in the same manner as the mother particles 2 except that the amount of nickel fine particle dispersion having an average particle diameter of 100 nm was changed. As a result of measuring the height and coverage of the protrusions by image analysis of the SEM image, the height of the protrusions was 100 nm and the coverage of the protrusions was about 44.5 area%. Further, the saturation magnetization per unit volume of the mother particle 8 was measured and found to be 49.5 emu / cm ³ .

(9) Preparation of mother particles 9 Mother particles 9 having protrusions (core nickel) were prepared in the same manner as the mother particles 2 except that the amount of nickel fine particle dispersion having an average particle diameter of 100 nm was changed. As a result of measuring the height and the coverage of the protrusion by image analysis of the SEM image, the height of the protrusion was 100 nm and the coverage of the protrusion was about 27.3 area%. Further, the saturation magnetization per unit volume of the mother particles 9 was measured and found to be 29.8 emu / cm ³ .

(10) Preparation of mother particles 10 Mother particles 10 having protrusions (core nickel) were prepared in the same manner as the mother particles 2 except that the amount of nickel fine particle dispersion having an average particle diameter of 100 nm was changed. As a result of measuring the height and coverage of the protrusions by image analysis of the SEM image, the height of the protrusions was 100 nm and the coverage of the protrusions was about 9.1 area%. Further, the saturation magnetization per unit volume of the mother particle 10 was measured and found to be 9.9 emu / cm ³ .

(Preparation of silicone oligomer 1)
A solution was prepared by blending 50 g of triethoxyphenylsilane with 10 g of methanol. While stirring this, a solution of 6 g of distilled water and 0.5 g of acetic acid was added, and the mixture was heated at 80 ° C. for a certain time to perform hydrolysis and polycondensation reaction. Once cooled to 0 ° C., 6 g of tetraethoxysilane was added dropwise and stirred at room temperature for 2 hours to obtain a silicone oligomer containing a phenyl group in the siloxane skeleton and having a trifunctional terminal. The resulting silicone oligomer had a weight average molecular weight of 1100. Methanol was added to the obtained silicone oligomer solution to prepare a treatment liquid having a solid content of 20% by mass. The weight average molecular weight was measured by gel permeation chromatography (GPC) using a standard polystyrene calibration curve, and the measurement conditions were as follows.
<GPC conditions>
Equipment used: Hitachi L-6000 (Hitachi, Ltd.)
Column: Gel pack GL-R420 + Gel pack GL-R430 + Gel pack GL-R440 (3 in total) [All are trade names manufactured by Hitachi Chemical Co., Ltd.]
Eluent: Tetrahydrofuran Measurement temperature: 40 ° C
Flow rate: 1.75 mL / min Detector: L-3300RI [Hitachi, Ltd.]

(Preparation of silicone oligomer 2)
To a glass flask equipped with a stirrer, a condenser and a thermometer, 5 g of activated clay and 4.8 g of distilled water were added to a solution containing 118 g of 3-glycidoxypropyltrimethoxysilane and 5.9 g of methanol, and 75 ° C. And a silicone oligomer having a weight average molecular weight of 1300 was obtained. The obtained silicone oligomer has a methoxy group or a silanol group as a terminal functional group that reacts with a hydroxyl group. Methanol was added to the obtained silicone oligomer solution to prepare a treatment liquid having a solid content of 20% by mass.

(Preparation of insulator particles 1)
3-acryloxypropyltrimethoxysilane (73.13% by weight), methyl acrylate (5.42% by weight), methacrylic acid (19.5% by weight), and azobisisobutyronitrile (1.95% by weight) Fine particles were prepared with the composition of Charge each of the above compounds into a 500 mL flask at once (adjusting the concentration), add 350 g of acetonitrile as a solvent, replace the dissolved oxygen with nitrogen (100 mL / min) for 1 hour, and then dissolve the oxygen analyzer (Iijima Electronics Co., Ltd.). When the dissolved oxygen amount was measured using Do meter B506), it was 0.07 mg / mL. Thereafter, the mixture was stirred for about 6 hours at a water bath temperature of 80 ° C. using a stirrer to obtain an organic-inorganic hybrid particle dispersion. Next, the particles in the obtained dispersion were settled by a centrifugal separator, and after removing the supernatant, acetonitrile was added again to redisperse the particles. Thereafter, 1.76 g of an aqueous ammonia solution (28% by mass) was added as a particle curing catalyst (equimolar to the charged carboxyl group amount of the particles) to crosslink the particles. Subsequently, the particles were sedimented again by centrifugation, the supernatant was removed, and the particles were redispersed in methanol. The obtained organic-inorganic hybrid particles were designated as insulator particles 1. It was 300 nm when the average particle diameter of the insulator particle | grains 1 was measured by SEM.

(Preparation of insulator particles 2)
Insulator particles 2 having an average particle diameter of 180 nm were prepared in the same manner as the insulator particles 1 except that the concentration of the compound at the time of particle preparation was changed (the composition was the same).

(Preparation of insulator particles 3)
Insulator particles 3 having an average particle diameter of 220 nm were prepared by the same method as that of insulator particles 1 except that the concentration of the compound at the time of particle preparation was changed (the composition was the same).

(Preparation of insulator particles 4)
Insulator particles 4 having an average particle diameter of 480 nm were prepared in the same manner as the insulator particles 1 except that the concentration of the compound at the time of particle preparation was changed (the composition was the same).

(Preparation of insulator particles 5)
Insulator particles 5 having an average particle diameter of 550 nm were prepared in the same manner as the insulator particles 1 except that the concentration of the compound at the time of particle preparation was changed (the composition was the same).

(Conductive particles 1)
A reaction liquid was prepared by dissolving 8 mmol of mercaptoacetic acid in 200 mL of methanol. Next, 10 g of the mother particle 1 was added to the reaction solution, and the mixture was stirred at room temperature for 2 hours with a three-one motor and a stirring blade having a diameter of 45 mm. After washing with methanol, the base particle 1 was filtered with a membrane filter (manufactured by Millipore) having a pore diameter of 3 μm to obtain 10 g of base particles 1 having a carboxyl group on the surface.

  Next, a 30% by mass polyethyleneimine aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.) having a molecular weight of 70,000 was diluted with ultrapure water to obtain a 0.3% by mass polyethyleneimine aqueous solution. 10 g of the above mother particle 1 having a carboxyl group was added to a 0.3% by mass polyethyleneimine aqueous solution and stirred at room temperature for 15 minutes. Next, the mother particle 1 was filtered with a membrane filter (manufactured by Millipore) having a pore diameter of 3 μm, put in 200 g of ultrapure water and stirred at room temperature for 5 minutes. Further, the mother particle 1 was filtered with a membrane filter (manufactured by Millipore) having a pore diameter of 3 μm. Washing was performed twice with 200 g of ultrapure water on the membrane filter to remove unimsorbed polyethyleneimine, thereby producing mother particles 1 having an amino group-containing polymer on the surface.

  Next, the silicone oligomer 2 was coated on the insulator particles 1 to prepare a methanol dispersion medium of the insulator particles 1 having a glycidyl group-containing oligomer on the surface.

  Next, the base particles 1 treated with polyethyleneimine are immersed in isopropyl alcohol, and a methanol dispersion medium of the insulator particles 1 having a glycidyl group-containing oligomer is dropped on the surface, whereby the coverage of the insulator particles is 30 area%. Conductive particles were produced. The coverage was adjusted by the dropping amount. Next, the entire conductive particles obtained with the silicone oligomer 1 were treated, washed, and the surface was hydrophobized. Thereafter, drying was performed under conditions of 80 ° C. for 30 minutes, and conductive particles 1 were produced by heating and drying at 120 ° C. for 1 hour.

(Conductive particles 2)
Conductive particles 2 were produced in the same manner as the conductive particles 1 except that the mother particles 2 were used instead of the mother particles 1. The coverage of the insulator particles was 30 area%.

(Conductive particles 3)
The conductive particles 3 were produced in the same manner as the conductive particles 1 except that the mother particles 3 were used instead of the mother particles 1. The coverage of the insulator particles was 30 area%.

(Conductive particles 4)
Conductive particles 4 were produced in the same manner as the conductive particles 1 except that the mother particles 4 were used instead of the mother particles 1. The coverage of the insulator particles was 30 area%.

(Conductive particles 5)
Conductive particles 5 were produced in the same manner as the conductive particles 1 except that the mother particles 5 were used instead of the mother particles 1. The coverage of the insulator particles was 30 area%.

(Conductive particles 6)
The conductive particles 6 were produced in the same manner as the conductive particles 1 except that the mother particles 6 were used instead of the mother particles 1. The coverage of the insulator particles was 30 area%.

(Conductive particles 7)
Conductive particles 7 were produced in the same manner as the conductive particles 1 except that the mother particles 7 were used instead of the mother particles 1. The coverage of the insulator particles was 30 area%.

(Conductive particles 8)
Conductive particles 8 were produced in the same manner as the conductive particles 1 except that the mother particles 8 were used instead of the mother particles 1. The coverage of the insulator particles was 30 area%.

(Conductive particles 9)
Conductive particles 9 were produced in the same manner as the conductive particles 1 except that the mother particles 9 were used instead of the mother particles 1. The coverage of the insulator particles was 30 area%.

(Conductive particles 10)
The conductive particles 10 were produced in the same manner as the conductive particles 1 except that the mother particles 10 were used instead of the mother particles 1. The coverage of the insulator particles was 30 area%.

(Conductive particles 11)
Conductive particles 11 were produced in the same manner as the conductive particles 2 except that the insulator particles 2 were used instead of the insulator particles 1. The coverage of the insulator particles was 30 area%.

(Conductive particles 12)
Conductive particles 12 were produced in the same manner as the conductive particles 2 except that the insulator particles 3 were used instead of the insulator particles 1. The coverage of the insulator particles was 30 area%.

(Conductive particles 13)
Conductive particles 13 were produced in the same manner as the conductive particles 2 except that the insulator particles 4 were used instead of the insulator particles 1. The coverage of the insulator particles was 30 area%.

(Conductive particles 14)
Conductive particles 14 were produced in the same manner as the conductive particles 2 except that the insulator particles 5 were used instead of the insulator particles 1. The coverage of the insulator particles was 30 area%.

Example 1
100 g of phenoxy resin (trade name, PKHC, manufactured by Union Carbide) and 75 g of acrylic rubber (copolymer of 40 parts of butyl acrylate, 30 parts of ethyl acrylate, 30 parts of acrylonitrile, and 3 parts of glycidyl methacrylate, molecular weight: 850,000) Ethyl and toluene were dissolved in 300 g of a solvent mixed at a weight ratio of 1: 1 to obtain a 30% by mass solution. Next, 300 g of liquid epoxy (Eboxy equivalent 185, manufactured by Asahi Kasei Epoxy Co., Ltd., NovaCure HX-3941) containing microcapsule-type latent curing agent and 400 g of liquid epoxy resin (YL980 manufactured by Yuka Shell Epoxy Co., Ltd.) are added to the above solution. In addition to the above, the adhesive solution 1 was prepared by stirring.

  Next, a silica slurry in which silica having a particle size of 14 nm (R202, manufactured by Nippon Aerosil Co., Ltd.) was dispersed in a solvent so that the silica solid content was 5% by mass with respect to the adhesive solid content was added to the adhesive solution 1.

  The conductive particles 1 were ultrasonically dispersed in 10 g of a solvent in which ethyl acetate and toluene were mixed at a mass ratio of 1: 1. Ultrasonic dispersion was performed for 1 minute in an ultrasonic bath of 38 kHz, 400 W, 20 L (test apparatus: US 107 Fujimoto Kagaku brand name).

The dispersion was dispersed in the adhesive solution 1 to prepare an adhesive solution 2. This adhesive solution 2 was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 40 μm) with a roll coater and dried at 90 ° C. for 10 minutes to produce an anisotropic conductive adhesive film A having a thickness of 10 μm. This anisotropic conductive adhesive film contained 100,000 particles / mm ² per unit area.

  Also, the adhesive solution 1 was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 40 μm) with a roll coater and dried at 90 ° C. for 10 minutes to prepare an anisotropic conductive adhesive film B having a thickness of 3 μm.

  Further, the adhesive solution 1 was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 40 μm) with a roll coater, and dried at 90 ° C. for 10 minutes to prepare an anisotropic conductive adhesive film C having a thickness of 10 μm.

  Next, the anisotropic conductive adhesive film B, the anisotropic conductive adhesive film A, and the anisotropic conductive adhesive film C are laminated in this order, and the anisotropic conductive adhesive film D having three layers is laminated. Was made.

  Next, using the produced anisotropic conductive adhesive film D, a chip (1.7 × 1.7 mm, thickness) with gold bumps (area: 30 × 90 μm, space 8 μm, height: 15 μm, bump number 362) is used. : 0.5 μm) and a glass substrate with a circuit (thickness: 0.7 mm) were connected as shown below.

After the anisotropic conductive adhesive film D was attached to a glass substrate with a circuit at 80 ° C. and 0.98 MPa (10 kgf / cm ² ), the separator was peeled off, and the bump of the chip with the gold bump and the circuit of the glass substrate with the circuit The alignment with the electrode was performed. Next, the main connection was performed by heating and pressing from above the chip under the conditions of 190 ° C., 40 g / bump, and 10 seconds. The evaluation results are shown in Table 1.

(Example 2)
A connection structure was produced in the same manner as in Example 1 except that the conductive particles 2 were used instead of the conductive particles 1. The evaluation results are shown in Table 1.

(Example 3)
A connection structure was produced in the same manner as in Example 1 except that the conductive particles 3 were used instead of the conductive particles 1. The evaluation results are shown in Table 1.

(Example 7)
A connection structure was produced in the same manner as in Example 1 except that the conductive particles 4 were used instead of the conductive particles 1. The evaluation results are shown in Table 1.

(Example 8)
A connection structure was produced in the same manner as in Example 1 except that the conductive particles 5 were used instead of the conductive particles 1. The evaluation results are shown in Table 1.

(Comparative Example 3)
A connection structure was produced in the same manner as in Example 1 except that the conductive particles 6 were used instead of the conductive particles 1. The evaluation results are shown in Table 1.

(Comparative Example 4)
A connection structure was produced in the same manner as in Example 1 except that the conductive particles 7 were used instead of the conductive particles 1. The evaluation results are shown in Table 1.

(Comparative Example 5)
A connection structure was produced in the same manner as in Example 1 except that the conductive particles 8 were used instead of the conductive particles 1. The evaluation results are shown in Table 1.

Example 4
A connection structure was produced in the same manner as in Example 1 except that the conductive particles 9 were used instead of the conductive particles 1. The evaluation results are shown in Table 1.

(Example 5)
A connection structure was produced in the same manner as in Example 1 except that the conductive particles 10 were used instead of the conductive particles 1. The evaluation results are shown in Table 1.

Example 9
A connection structure was produced in the same manner as in Example 1 except that the conductive particles 11 were used instead of the conductive particles 1. The evaluation results are shown in Table 1.

(Example 6)
A connection structure was produced in the same manner as in Example 1 except that the conductive particles 12 were used instead of the conductive particles 1. The evaluation results are shown in Table 1.

(Example 10)
A connection structure was produced in the same manner as in Example 1 except that the conductive particles 13 were used instead of the conductive particles 1. The evaluation results are shown in Table 1.

(Comparative Example 8)
A connection structure was produced in the same manner as in Example 1 except that the conductive particles 14 were used instead of the conductive particles 1. The evaluation results are shown in Table 1.

(Insulation resistance test and conduction resistance test)
An insulation resistance test and a conduction resistance test were performed on the connection structures manufactured in Examples 1 to 10 and Comparative Examples 3 to 5 and 8. It is important that the anisotropic conductive adhesive film has a high insulation resistance between the chip electrodes (bumps) in the non-pressing direction and a low conduction resistance between the chip electrode / glass electrode in the pressing direction. In the insulation resistance test, the insulation resistance value between 20 samples of chip electrodes was measured, and the average value of the minimum values of each sample was calculated. Further, the yield was calculated when the insulation resistance value> 10 ⁹ (Ω) was regarded as a good product.

  Furthermore, the conduction resistance value between the chip electrode / glass electrode of 14 samples was measured, and the average value was calculated. The measurement of the conduction resistance value was performed at the initial stage and after the moisture absorption heat resistance test (left for 500 hours under conditions of a temperature of 85 ° C. and a humidity of 85%).

(Protrusion coverage)
Prepare 100 SEM images of the mother particles, and measure the area occupied by the protrusions in the center of the image (in the circle whose diameter is the radius of the plastic core) by analyzing the outline of the valleys of the protrusions. The coverage of the protruding portion was calculated as the area occupied by the protruding portion relative to the total area of the central portion.

(Coating variation of insulator particles (CV))
By preparing 100 SEM images of conductive particles and analyzing the contour of the insulator particles for the area occupied by the insulator particles existing in the center of the image (in the circle whose diameter is the radius of the plastic core) Measurement was performed to calculate the coating variation of the insulator particles.

Whether the evaluation results obtained for the insulation resistance and the conduction resistance after the moisture absorption heat test satisfy the characteristics required for the connection structure of the circuit board was determined by the following index.
AA: Satisfactory enough A: Satisfied B: Satisfied but relatively inferior to A C: Unusable

  Example 1 is an example in which silica is used for the core material. Since the phosphorus content of the plating was high and the protruding core material was a non-magnetic material, the saturation magnetization of the mother particles showed a low value. Therefore, since the mother particles are less likely to aggregate when the insulator particles are coated, and the coating variation (CV) of the insulator particles is small, the insulation properties are particularly good. Examples 2, 3, 7 and 8 are examples in which nickel is used for the core material of the protrusion. Therefore, the saturation magnetization of the mother particles was higher than that in Example 1. As the particle diameter of the mother particle becomes smaller, aggregation tends to occur due to the influence of magnetism, and as a result, the coating variation (CV) increases and the insulating property decreases. When the particle diameter of the mother particles was less than 2 μm, magnetic aggregation was likely to occur and the insulation resistance value was low. Moreover, since the particle diameter of the mother particles was small, the conductivity was low (Comparative Example 3).

When the particle diameter of the mother particles exceeded 3 μm, the insulating properties were greatly reduced (Comparative Example 4). Further, when the saturation magnetization of the mother particles exceeded 45 emu / cm ³ (Comparative Example 5), magnetic aggregation was likely to occur and the insulation resistance was reduced. This phenomenon tends to occur particularly when the particle diameter of the mother particles is 3 μm or less. In addition, when the coverage of the protrusions was low (Examples 4 and 5), the saturation magnetization of the mother particles was small, and excellent insulation was obtained. When the particle diameter of the insulator particles was less than 200 nm (Example 9), the insulation was lowered. Further, when the particle diameter of the insulator particles approaches 500 nm (Example 10), the insulation and conductivity tend to decrease. When the particle diameter of the insulator particles exceeds 500 nm (Comparative Example 8), the connection structure Could not be used as a body.

  DESCRIPTION OF SYMBOLS 1 ... Insulator child particle, 2 ... Mother particle, 3 ... Insulation coating layer, 21 ... Plastic core, 22 ... Plating layer, 23 ... Core material, 23a ... Projection , 30 ... conductive particles, 31 ... adhesive, 32 ... conductive particle containing layer, 33, 34 ... conductive particle non-containing layer, 35 ... inorganic oxide particles, 40 ... different Isotropic conductive adhesive, 40a ... circuit connection member, 41 ... first circuit board (IC chip), 42 ... first circuit electrode (metal bump), 43 ... second circuit Substrate (glass substrate), 44... Second circuit electrode (ITO or IZO electrode), 50... Connection structure.

Claims (10)

Mother particles having a plastic core and a plating layer covering the surface of the plastic core and having at least a nickel / phosphorus alloy layer;
Insulating particles covering the surface of the mother particles, and conductive particles comprising:
The mother particle has a particle size of 2.0 μm or more and 3.0 μm or less,
The saturation magnetization of the mother particle is 45 emu / cm ³ or less,
Conductive particles having a particle size of the insulator particles of 180 nm or more and 500 nm or less. The mother particles have protrusions on the surface;
The conductive particle according to claim 1, wherein a height of the protrusion is smaller than a particle diameter of the insulator particle. The mother particles have protrusions on the surface;
The protrusion is formed by covering the surface of the plastic core with the core material attached thereto with the plating layer,
The conductive particle according to claim 1, wherein the core material is a non-magnetic material.   The electroconductive particle as described in any one of Claims 1-3 whose phosphorus content rate of the said nickel / phosphorus alloy layer is 1.0 mass% or more and 10.0 mass% or less. The coverage of the insulator particles is 20 to 50%,
C. Variation in coating of the insulator particles V. The electroconductive particle according to any one of claims 1 to 4, which is 0.3 or less.   The conductive particles according to any one of claims 1 to 5, wherein the insulator particles have a layer made of a polymer or oligomer having a weight average molecular weight of 1000 or more.   The conductive particles according to any one of claims 1 to 6, wherein the mother particle further has a layer made of a polymer or oligomer having a weight average molecular weight of 1000 or more.   The conductive particles according to any one of claims 1 to 7, wherein a particle diameter of the insulator particles is 200 nm or more and 400 nm or less.   An anisotropic conductive adhesive film in which the conductive particles according to claim 1 are dispersed in an adhesive. A first circuit member having a first circuit electrode formed on the main surface of the first circuit board;
A second circuit member having a second circuit electrode formed on the main surface of the second circuit board;
The first circuit board is provided between the main surface of the first circuit board and the main surface of the second circuit board, and the first circuit electrode and the second circuit electrode are arranged to face each other. And a circuit connecting member for connecting the second circuit members,
A circuit member connection structure comprising:
The circuit connection member comprises a cured product of the anisotropic conductive adhesive film according to claim 9,
A connection structure for circuit members, wherein the first circuit electrode and the second circuit electrode facing each other are electrically connected via flat conductive particles.

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