JP6089462B2 - Conductive particles, manufacturing method thereof, and conductive material including the same - Google Patents

Description

The present invention relates to conductive particles , a method for producing the same, and a conductive material including the same.

  Metal or resin powder for the purpose of electrical connection between electrode terminals of minute pitch, as represented by electrical connection of electrodes of a liquid crystal display panel to a circuit board of a driving LSI chip A conductive filler having a surface electrolessly plated with metal is used.

  The present applicant has previously proposed a conductive electroless plating powder in which an electroless plating layer of nickel or a nickel alloy is formed on the particle surface using a polymer as a core particle as a conductive filler having high conductivity. (Patent Documents 1 to 3).

  Commonly used polymer core particles are thermoplastic resins such as polyethylene, polypropylene, polyvinyl chloride, polystyrene, polybutene, polyamide, polyacrylate, polyacrylonitrile, polyacetal, ionomer, polyester, alkyd resin, phenol resin, urea Resins, melamine resins, benzoguanamine resins, xylene resins, silicone resins, epoxy resins or diallyl phthalate resins.

  Patent Document 4 listed below is a conductive particle having a base particle and a conductive coating layer formed on the surface of the particle, and the compression elastic modulus of the base particle is directed from the center of the particle toward the surface. Thus, conductive particles using those that change stepwise or continuously have been proposed.

  In recent years, finer pitches and smaller areas of electrodes have been achieved by downsizing electronic components. Due to this, in the electrical connection using the conductive filler, there is a tendency that the number of particles interposed between the electrodes tends to decrease, so that the electrical resistance value increases. Therefore, a conductive filler having higher conductivity per particle is required.

JP 08-31655 A JP 2000-243132 A JP 2010-118334 A JP 2004-47343 A

  Therefore, the subject of this invention is providing the electroconductive particle which the electroconductive performance improved further than the electroconductive particle of the prior art mentioned above.

As a result of intensive studies by the present inventor to solve the above-mentioned problems, the present inventor has conductive particles having core material particles and a conductive layer formed of a metal film covering the core material particles, wherein the core material particles are polyorganosiloxane. A particle having a silica coating layer in which the surface of the core particle consisting of (a) is coated with silica, and the ratio of the thickness of the silica coating layer to the diameter of the core particle consisting of the polyorganosiloxane (a) is in a specific range. It has been found that the above-mentioned problems can be solved by using a material.

The present invention has been made based on the above knowledge, and the conductive particles of the present invention are conductive particles having a spherical core material particle and a conductive layer made of a metal film covering the core material particle. The core particles are particles having a silica coating layer in which the surface of the core particles made of polyorganosiloxane (a) is coated with silica, and the silica coating layer has a diameter corresponding to the diameter of the core particles made of polyorganosiloxane (a). The thickness ratio is 0.07 to 1.5.

  The conductive particles of the present invention have high conductivity. Therefore, when the conductive particles of the present invention are used, for example, as a conductive material for an anisotropic conductive film or anisotropic conductive paste, such a conductive film or conductive paste can be obtained having high conductivity.

Sectional drawing which shows the structure of the core material particle used by this invention.

Hereinafter, the present invention will be described based on preferred embodiments thereof. As described above, the conductive particle of the present invention is a conductive particle having a core material particle and a conductive layer formed of a metal film covering the core material particle, and the core particle is a polyorganosiloxane (a). A particle having a silica coating layer in which the surface of the core particle composed of silica is coated with silica , and the ratio of the thickness of the silica coating layer to the diameter of the core particle composed of the polyorganosiloxane (a) is 0.07 to 1.5. It is characterized by being.

The conductive particles of the present invention are obtained by coating the surface of relatively soft core particles made of polyorganosiloxane (a) with silica harder than the core particles. The hard silica coating layer effectively eliminates the resin between the electrodes at the time of thermocompression bonding and the oxide film on the electrode surface, thereby contributing to the improvement of the connection reliability of the electrodes. On the other hand, since the core particles made of the soft polyorganosiloxane (a) are appropriately crushed during thermocompression bonding, a sufficient contact area between the conductive particles and the electrode can be secured, and thus the conductive particles of the present invention. Can ensure good conduction.
Moreover, in the connection structure using the anisotropic conductive adhesive film containing conductive particles, in many cases, the conductive state in the anisotropic conductive adhesive film is checked in order to confirm the connection state by the anisotropic conductive adhesive film. The indentation generated on the terminal of the substrate due to the conductive particles is observed from the substrate side using a microscope or the like, but those using polymer particles as the core material particles are too soft and are sufficient for the terminal of the substrate There is a problem that an indentation that can be observed on the terminal is less likely to occur. On the other hand, the conductive particles of the present invention can be expected to improve indentation characteristics since the core particles made of polyorganosiloxane (a) are coated with hard silica particles as the core particles.

In the present invention, the core particles composed of the polyorganosiloxane (a) have a 10% compressive strength at 20 ° C. of particles formed of the polyorganosiloxane (a) alone of 50 kgf / mm ² or less, preferably 1 to 50 kgf. / mm ² is preferable in that the core particles composed of the polyorganosiloxane (a) are appropriately crushed during thermocompression bonding, and a sufficient contact area with the electrode can be secured.

In the conductive particles of the present invention, the silica covering the core particles composed of the polyorganosiloxane (a) is difficult to eliminate the resin between the electrodes and the oxide film on the electrode surface if it is too crushed during thermocompression bonding. a condition that is greater than 10% compression strength of the core particles, 10% compression strength at 20 ° C. of silica alone formed particles is 3 kgf / mm ² or more, preferably be those of 3~100kgf / mm ² preferable.

In the present invention, the core particle made of polyorganosiloxane (a) is preferably an alkoxysilane hydrolyzed condensate, and the polyorganosiloxane (a) can be changed appropriately to change the type of polyorganosiloxane (a). The softness and chemical or physical properties of the resulting core particles can also be easily changed.
Examples of the alkoxysilane include methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, methyltris (methoxyethoxy) silane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, and butyltrimethoxysilane. , Vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, etc. Organotrialkoxysilanes; Organodialkoxysilanes such as dimethyldimethoxysilane, methylphenyldimethoxysilane, diphenyldimethoxysilane; Tetramethoxy It can be used tetraacyl alkoxysilanes such as tetra-acetoxy silane; silane, tetraethoxysilane, tetrapropoxysilane, tetra-alkoxysilanes such as tetra butoxy silane; tetramethyl silane, tetraalkyl alkoxysilanes such as tetraethyl silane.

  Further, the silica coating layer on the core particles made of the polyorganosiloxane (a) has a ratio of the thickness (T) of the silica coating layer to the diameter (D) of the core particles made of the polyorganosiloxane (a) (T / D, 1) is 0.07 to 1.5, preferably 0.08 to 0.8, the effect of eliminating the resin between the electrodes and the oxide film on the electrode surface during thermocompression bonding is enhanced. Moreover, it is preferable from the viewpoint of ensuring a sufficient contact area with the electrode.

  In the present invention, the measurement of the 10% compressive strength of the core particles composed of the polyorganosiloxane (a) and the particles formed of silica alone is the micro compression tester MCTM-500 manufactured by Shimadzu Corporation) The compression load speed was 0.054 gf / sec.

  In the present invention, the core particles are formed on the surface of the core particles composed of the polyorganosiloxane (a), and the decomposition temperature of the organic component is different from that of the polyorganosiloxane (a). The core-shell particles having a shell layer composed of the polyorganosiloxane (b) having a low decomposition temperature are higher than the decomposition temperature of the organic component contained in the polyorganosiloxane (b) and are contained in the polyorganosiloxane (a). It is preferable that the heat treatment can be performed at a temperature lower than the decomposition temperature of the organic component from the viewpoint that the conductive particles have higher conductivity and excellent connection reliability between the electrodes.

That is, the core material particles used in the present invention can be produced by sequentially performing the following steps (A) to (C).
(A) Core particle manufacturing process.
(B) Shell layer forming step.
(C) Heat treatment process.

Hereinafter, the steps (A) to (C) will be described.
(A) Step;
The core particle production step of the step (A) is a step of obtaining core particles made of polyorganosiloxane (a) by hydrolyzing and dehydrating and condensing alkoxysilane using a sol-gel method.

  In the step (A), specifically, a solution obtained by mixing water and alkoxysilane (a1) is stirred to hydrolyze the alkoxysilane (a1). Next, an aqueous ammonia solution is added and dehydrated to form core particles made of polyorganosiloxane (a).

  The reaction temperature and reaction time for hydrolysis and dehydration condensation depend on the type of alkoxysilane used as a raw material, but are usually in the range of -10 ° C. to 60 ° C. for 1 hour to 24 hours. is there.

 The raw material alkoxysilane (a1) in the step (A) is, for example, methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, methyltris (methoxyethoxy) silane, ethyltrimethoxysilane, ethyltriethoxysilane, Propyltriethoxysilane, butyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane, γ -Organotrialkoxysilanes such as methacryloxypropyltrimethoxysilane; Organodialkoxys such as dimethyldimethoxysilane, methylphenyldimethoxysilane, diphenyldimethoxysilane Run: Tetraalkoxysilane such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane; tetraalkylalkoxysilane such as tetramethylmethoxysilane, tetraethylethoxysilane; tetraacylalkoxysilane such as tetraacetoxysilane Of these, organotrialkoxysilane is preferable, and methyltrimethoxysilane is particularly preferable.

  The water used in the reaction is preferably free from unnecessary components such as insoluble matter, ions, and silicon from the viewpoint of obtaining a pure product. Therefore, it is preferable to use a material from which impurities have been removed in advance using microfiltration, ion exchange resin, ultraviolet light, RO (reverse osmosis membrane) or the like.

  The concentration of the aqueous ammonia solution used for the reaction is from 0.1M to 10M, preferably from 0.5M to 5M. When the concentration of the aqueous ammonia solution is less than 0.1M, the amount of the aqueous ammonia solution added is increased, the addition time becomes longer, and the particle size distribution tends to be widened, which is not preferable. In addition, when the concentration of the aqueous ammonia solution is higher than 10M, the amount of the aqueous ammonia solution added is reduced, and an error in addition is not preferable.

(B) step;
Unlike the alkoxysilane (a1) used in the step (A), the shell layer forming step in the step (B) is more organic than the polyorganosiloxane (a) in the upper layer of the reaction solution in the step (A). An alkoxysilane (b1) capable of obtaining a polyorganosiloxane (b) having a low decomposition temperature is added, and then the reaction is completed, and the polyorganosiloxane (b) is formed on the surface of the core particles obtained in the step (A). This is a step of obtaining core-shell particles in which a shell layer made of is formed.

  Specifically, first, water is added to the reaction solution in which the core particles composed of the polyorganosiloxane (a) produced in the step (A) are dispersed and stirred. In the upper layer of this solution, unlike the alkoxysilane (a1) used in the step (A), an alkoxysilane capable of obtaining a polyorganosiloxane (b) having a lower decomposition temperature of the organic component than the polyorganosiloxane (a). Slowly add (b1) so that the interface between the two layers can be maintained. After completion of the addition, stirring is continued as it is until the upper layer disappears and becomes one layer along with hydrolysis and dehydration condensation of the alkoxysilane (b1).

  After that, when the process proceeds to the next step with the raw material remaining, fine particles are by-produced. Therefore, stirring is continued for about 0.5 to 2 hours so that the fine particles are not by-produced.

  The reaction temperature in the formation of the shell layer depends on the type of alkoxysilane (b1) used as a raw material, but is usually in the range of −10 ° C. to 60 ° C.

  The water to be added is preferably water from which impurities have been removed in the same manner as in step (A).

  The amount of water to be added is selected between 1 part by weight and 20 parts by weight with respect to the reaction solution after step (A). Preferably, it is 5 to 12 parts by weight. When the amount of water to be added is less than 1 part by weight, a large amount of gel-like compound is generated, and it is difficult to form a shell layer on the particle surface, which is not preferable. When the amount of water to be added is more than 20 parts by weight, the reaction solution becomes dilute, the reaction rate and yield of the formation of the shell layer are reduced, and this is not preferable because of lack of practicality.

  The alkoxysilane (b1) to be added to the upper layer of the solution is different from the compounds used in the step (A) among the alkoxysilanes exemplified in the step (A), and from the polyorganosiloxane (a). A substance capable of obtaining a polyorganosiloxane (b) having a low decomposition temperature of the organic component is selected. Among them, organotrialkoxysilane is preferable, and in the case where methyltrimethoxysilane is used as alkoxysilane (a1) in the step (A), vinyltrimethoxysilane is preferable as alkoxysilane (b1).

  Moreover, although the addition amount of the alkoxysilane (b1) added to the upper layer of the said solution is based also on the thickness of the desired shell layer, it is 1 normally with respect to the alkoxysilane (a1) used for the production | generation of the particle | grains used as a core. The range is from 15 parts by weight to 15 parts by weight.

  Next, 28% by weight of an aqueous ammonia solution is added and ripened to complete the reaction. The amount of the aqueous ammonia solution to be added is selected in such a range that the ammonia concentration in the solution in which the reaction is completed is 0.05% by weight or more and 0.5% by weight or less. This aging temperature is usually in the range of −10 ° C. to 60 ° C. The aging time is in the range of 1 hour to 24 hours.

  After completing the reaction, if necessary, classification treatment is performed, and the produced particles are sufficiently washed and then dried. Although there is no restriction | limiting in particular as a classification processing method, Wet classification methods, such as a decantation and a water husk classification, are preferable.

  The drying treatment depends on the types of raw materials and solvents and the amount of treatment, but is usually performed at a temperature in the range of room temperature to 100 ° C. for 1 hour to 24 hours.

(C) step;
In the heat treatment step (C), the core-shell particles obtained in the step (B) are heat-treated to form the polyorganosiloxane (b) on the surface of the core particles made of the polyorganosiloxane (a). This is a step of obtaining particles in which the surface of the core particles made of polyorganosiloxane (a) is coated with silica from the core-shell particles having a shell layer.

  Specifically, the particles composed of the two types of polyorganosiloxane obtained in the step (B) are lower than the decomposition temperature of the organic component of the polyorganosiloxane (a) and the decomposition of the organic component of the polyorganosiloxane (b). Heat treatment is performed in a temperature range higher than the temperature. Thereby, core material particles obtained by converting only the polyorganosiloxane (b) of the shell layer into silica can be obtained without changing the polyorganosiloxane (a) of the core particles.

  The temperature and time for the heat treatment depend on the type of polyorganosiloxane, the particle diameter, the amount of treatment, etc., but are usually selected in the range of 200 ° C. to 1000 ° C. for 3 hours to 24 hours. This heat treatment may be a one-stage process or a multi-stage process in which the temperature is sequentially raised, but in order to prevent particle cracking or chipping due to rapid temperature rise, cracking, etc. Is desirable.

  In addition, a major feature is that no surfactant is used in the above production method. Therefore, there are no impurities after the resulting particles are produced and concentrated in solution or dried, so there is no need to remove impurities by filtration, centrifugation, etc., and it is possible to obtain high production efficiency Also have.

  The conductive particles according to the present invention are preferably used in the form of spherical particles as core material particles from the viewpoint of excellent filling properties when used as a conductive filler. The average particle diameter of the core particles is 1 to 20 μm, preferably 1 to 10 μm, particularly preferably from 1 to 10 μm, from the viewpoint of being able to cope with a narrow pitch as conductive particles. In addition, the particle size deviation coefficient (CV value) of 10% or less, preferably 5% or less, with a sharp particle size distribution was used as the conductive particles in the anisotropic conductive film. In this case, it is preferable from the viewpoint that the effective contribution ratio to the connection becomes high.

  The electroconductive particle which concerns on this invention has the electroconductive layer by the metal film on the particle | grain surface of the said core material particle.

  The conductive particles according to the present invention may have a smooth surface. Alternatively, the conductive particles may have a plurality of protrusions protruding from the surface.

The physical properties of the protrusions are preferably such that the height H of the protrusions is on average 20 nm or more, particularly 50 nm or more. Although the number of protrusions depends on the particle size of the conductive particles, it is preferably 1 to 20000, particularly 5 to 5000 per particle, from the viewpoint of further improving the conductivity of the conductive particles. . The aspect ratio of the protrusion is preferably 0.5 or more, more preferably 1 or more. A large aspect ratio of the protrusions is advantageous because it can easily break through the oxide film. In addition, when an anisotropic conductive film is formed using conductive particles, if the aspect ratio of the protrusion is large, the resin exclusion property is increased, so that the conductivity is considered to be increased. The aspect ratio is a ratio defined by the ratio of the height H of the protrusion and the length D of the base of the protrusion, that is, H / D.
The aspect ratio of the protrusion is as described above, and the length D of the base of the protrusion of the conductive particles is preferably 5 to 500 nm, particularly preferably 10 to 400 nm, and the height H of the protrusion is 5 to 500 nm. In particular, the thickness is preferably 10 to 400 nm.

  The metal film is one of copper, nickel, cobalt, palladium, gold, platinum, rhodium, silver, zinc, iron, lead, tin, aluminum, indium, chromium, antimony, bismuth, germanium, cadmium, molybdenum, tungsten, etc. Or 2 or more types are mentioned.

  The film thickness of the conductive layer is usually about 0.001 to 2 μm, preferably 0.005 to 1.0 μm. When the film thickness of the conductive layer is less than 0.001 μm, it is difficult to obtain desired conductivity, and when it exceeds 2 μm, not only the usefulness is low from the viewpoint of specific gravity and price, but also the conductive particles of the present invention. Flexibility becomes difficult to be effectively expressed, and further, aggregation of conductive particles easily occurs in the process.

Examples of the method for forming the conductive layer include a method by electroless plating, a method in which particles are coated with metal fine powder alone, a method in which particles are coated with a paste obtained by mixing metal powder and a binder, vacuum deposition, ion plating. And physical vapor deposition methods such as coating and ion sputtering. Among these, the electroless plating method is preferable in consideration of the dispersibility of the obtained particles, the uniformity of the film thickness of the conductive layer, and the like.
In addition, since the core particles used in the present invention are excellent in plating adhesion, the electroless plating treatment method as a method for forming the conductive layer in the conductive particles of the present invention can be obtained from this point. Is the most preferred method.

  As an electroless plating treatment method, for example, a complexing agent is added and dispersed sufficiently in core particles made into an aqueous slurry by a known method and equipment, and then a chemical solution constituting a metal electroless plating solution is added. A method of adding and forming a metal coating is mentioned.

  The complexing agent may be appropriately selected from known various compounds having a complexing action on the metal ion to be used. For example, citric acid, hydroxyacetic acid, tartaric acid, malic acid, lactic acid, gluconic acid or Examples thereof include carboxylic acids (salts) such as alkali metal salts or ammonium salts, amino acids such as glycine, amine acids such as ethylenediamine and alkylamine, other ammonium, EDTA, and pyrophosphate (salt).

  In addition, as the electroless plating solution, one containing one or more metals such as copper, nickel, cobalt, palladium, gold, platinum, rhodium, silver, molybdenum, and tungsten is preferably used. A solution to which each aqueous solution of a reducing agent such as sodium hypophosphite, hydrazine, sodium borohydride, formic acid and a pH adjusting agent such as sodium hydroxide is added is used. Electroless plating solutions containing metals such as copper, nickel, silver, gold, and palladium are commercially available and can be obtained at low cost.

  The electroless plating layer covering the core material particles is not particularly limited as long as it is a layer containing each of the above metals, but a nickel or nickel alloy plating film is preferred, and a multilayer film containing at least one of these films. May be. Nickel or nickel alloy film can form an electroless plating layer with good peel resistance by tightly adhering to the core material particles, and also when other metal layers are formed in multiple layers on the upper surface In addition, there is an advantage that it effectively functions as an intermediate layer capable of ensuring strong bonding with the upper metal layer.

  Examples of the nickel alloy include nickel-phosphorus and nickel-boron. The contents of phosphorus and boron in the coating are not particularly limited, but are 1 to 15% by mass and 0.5 to 5% by mass, respectively. It is preferable that

  In the case of a multilayer film, a nickel alloy-gold multilayer film and a nickel alloy-palladium multilayer film are suitable. This multi-layer coating is superior in conductive performance as compared to nickel or nickel alloy single-layer coating.

As an example of the electroless plating method, an electroless nickel plating method will be described.
The core particles are preferably surface-modified as necessary so that the surface thereof has a precious metal ion scavenging ability or a precious metal ion scavenging ability. The noble metal ions are preferably palladium or silver ions. Having a precious metal ion scavenging ability means that the precious metal ion can be captured as a chelate or salt. In the case of surface modification so as to have the ability to trap noble metal ions, for example, methods described in JP-A Nos. 61-64882 and 2007-262495 can be used.

Using such core material particles, a noble metal is supported on the surface. Specifically, the core material particles are dispersed in a dilute acidic aqueous solution of a noble metal salt such as palladium chloride or silver nitrate. This traps noble metal ions on the surface of the particles. The concentration of the noble metal salt is sufficiently in the range of 1 × 10 ⁻⁷ to 1 × 10 ⁻² mol per 1 m ² of the particle surface area. The core particles in which the noble metal ions are captured are separated from the system and washed with water. Subsequently, the core material particles are suspended in water, and a reducing agent is added to the suspension so that noble metal ions are reduced. As a result, the noble metal is supported on the surface of the core particles. As the reducing agent, for example, sodium hypophosphite, sodium borohydride, potassium borohydride, dimethylamine borane, hydrazine, formalin and the like are used, and among these, the constituent material of the target nickel or nickel alloy film is used. It is preferable to select based on.

  Before capturing the noble metal ions on the surface of the core material particles, a sensitization treatment for adsorbing the tin ions on the surface of the particles may be performed. In order to adsorb the tin ions on the surface of the particles, for example, the surface-treated core material particles may be put into an aqueous solution of stannous chloride and stirred for a predetermined time.

  The core material particles that have been pretreated in this way are subjected to nickel or nickel alloy film forming treatment. In the following, as the nickel or nickel alloy film forming process, (a) a process for forming a nickel or nickel alloy film having a protrusion (hereinafter also referred to as a process), and (b) a nickel or nickel alloy film having a smooth surface Two types of processes (hereinafter also referred to as “b process”) for forming the film will be described.

As a process, the following a1 process and a2 process are performed.
Step a1 is an electroless nickel plating step in which an aqueous slurry of core material particles is mixed with an electroless nickel plating bath containing a dispersant, a nickel salt, a reducing agent, a complexing agent, and the like. In the a1 step, self-decomposition of the plating bath occurs simultaneously with the formation of the nickel or nickel alloy film on the core material particles. Since this self-decomposition occurs in the vicinity of the core particle, when the nickel or nickel alloy film is formed, the self-decomposed product is trapped on the surface of the core particle, thereby generating a nucleus of microprojections, and at the same time, the base film Is formed. A protrusion grows with the nucleus of the generated fine protrusion as a base point.

  In the step a1, the above-described core material particles are preferably sufficiently dispersed in water in a range of preferably 1 to 500 g / L, more preferably 5 to 300 g / L to prepare an aqueous slurry. The dispersing operation can be usually performed using stirring, high-speed stirring, or a shearing dispersion device such as a colloid mill or a homogenizer. Further, ultrasonic waves may be used in combination with the dispersion operation. If necessary, a dispersing agent such as a surfactant may be added in the dispersing operation. Next, the aqueous slurry of the core material particles subjected to the dispersion operation is added to an electroless nickel plating bath containing a nickel salt, a reducing agent, a complexing agent, various additives, and the like, and the electroless plating a1 step is performed.

  Examples of the dispersant described above include nonionic surfactants, zwitterionic surfactants, and / or water-soluble polymers. As the nonionic surfactant, polyoxyalkylene ether surfactants such as polyethylene glycol, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and the like can be used. As the zwitterionic surfactant, a betaine surfactant such as alkyldimethylacetic acid betaine, alkyldimethylcarboxymethylacetic acid betaine, and alkyldimethylaminoacetic acid betaine can be used. As the water-soluble polymer, polyvinyl alcohol, polyvinyl pyrrolidinone, hydroxyethyl cellulose and the like can be used. These dispersants can be used alone or in combination of two or more. The amount of the dispersant used is generally 0.5 to 30 g / L with respect to the volume of the liquid (electroless nickel plating bath) although it depends on the type. In particular, the amount of the dispersant used is preferably in the range of 1 to 10 g / L with respect to the volume of the liquid (electroless nickel plating bath) from the viewpoint of further improving the adhesion of the nickel or nickel alloy film.

  As the nickel salt, for example, nickel chloride, nickel sulfate, nickel acetate or the like is used, and the concentration is preferably in the range of 0.1 to 50 g / L. As the reducing agent, for example, the same ones used for the reduction of the noble metal ions described above can be used, and are selected based on the target constituent material of the base film. When a phosphorus compound such as sodium hypophosphite is used as the reducing agent, the concentration is preferably in the range of 0.1 to 50 g / L. When a boron compound such as sodium borohydride or potassium borohydride is used, the concentration is preferably in the range of 0.01 to 10 g / L. When hydrazine or a derivative thereof is used, the concentration is preferably in the range of 0.01 to 50 g / L.

  Examples of complexing agents include citric acid, hydroxyacetic acid, tartaric acid, malic acid, lactic acid, gluconic acid or carboxylic acids (salts) such as alkali metal salts and ammonium salts thereof, amino acids such as glycine, and amines such as ethylenediamine and alkylamine. A compound having a complexing action with respect to nickel ions, such as acid, other ammonium, EDTA, or pyrophosphoric acid (salt) is used, and these may be used alone or in combination of two or more. The concentration is preferably in the range of 1 to 100 g / L, more preferably 5 to 50 g / L. The pH of the preferred electroless nickel plating bath at this stage is in the range of 4-14. The electroless nickel plating reaction starts rapidly when an aqueous slurry of core particles is added, and is accompanied by the generation of hydrogen gas. The electroless plating a1 process ends when the generation of the hydrogen gas is not completely recognized.

  Next, in step a2, whether (i) a first aqueous solution containing one of a nickel salt, a reducing agent and an alkali and a second aqueous solution containing the remaining two are used following the step a1. Or (ii) using a first aqueous solution containing a nickel salt, a second aqueous solution containing a reducing agent, and a third aqueous solution containing an alkali, and using these aqueous solutions simultaneously and over time, step a1 Electroless nickel plating is added to the above solution. When these solutions are added, the plating reaction starts again. By adjusting the addition amount, the formed nickel or nickel alloy film can be controlled to a desired film thickness. After completion of the addition of the electroless nickel plating solution, the reaction is completed by continuing stirring while maintaining the solution temperature for a while after generation of hydrogen gas is not completely observed.

  In the case of (i), it is preferable to use a first aqueous solution containing a nickel salt and a second aqueous solution containing a reducing agent and an alkali, but the present invention is not limited to this combination. In this case, the first aqueous solution contains no reducing agent and alkali, and the second aqueous solution contains no nickel salt. As the nickel salt and the reducing agent, those described above can be used. As the alkali, for example, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide can be used. The same applies to the case (ii).

  In the case of (ii) above, the first to third aqueous solutions each contain a nickel salt, a reducing agent, and an alkali, and each aqueous solution contains no other two components other than the components.

  In any case of (i) and (ii), the concentration of the nickel salt in the aqueous solution is preferably 10 to 1000 g / L, particularly 50 to 500 g / L. The concentration of the reducing agent is preferably 100 to 1000 g / L, particularly 100 to 800 g / L when a phosphorus compound is used as the reducing agent. When using a boron compound as a reducing agent, it is preferable that it is 5-200 g / L, especially 10-100 g / L. When hydrazine or a derivative thereof is used as the reducing agent, it is preferably 5 to 200 g / L, particularly 10 to 100 g / L. The alkali concentration is preferably 5 to 500 g / L, more preferably 10 to 200 g / L.

  The step a2 is continuously performed after the end of the step a1, but instead of this, the step a1 and the step a2 may be intermittently performed. In this case, after completion of the step a1, the core material particles and the plating solution are separated by a method such as filtration, and the core material particles are newly dispersed in water to prepare an aqueous slurry, and the complexing agent is added thereto. Preferably, an aqueous solution dissolved in a concentration range of 1 to 100 g / L, more preferably 5 to 50 g / L is added, and the dispersant is preferably 0.5 to 30 g / L, more preferably 1 to 10 g / L. Alternatively, a method may be used in which an aqueous slurry is prepared by dissolution in step A2 and the aqueous solution is added to the aqueous slurry. In this way, particles coated with nickel or a nickel alloy film having the desired protrusions are obtained.

  Next, a case where (b) a process for forming a smooth nickel or nickel alloy film (b process) is performed instead of the a process will be described. The b process can be performed as follows. First, an aqueous slurry containing pretreated core material particles, a dispersant, and a complexing agent is prepared. Then, the first aqueous solution and the second aqueous solution (i) described in the step a2 are used, or the first to third aqueous solutions (ii) are used. Electroless nickel plating is performed by adding over time. The pH of the plating solution obtained by adding each aqueous solution to the aqueous slurry is preferably adjusted to a range of 3 to 11, for example. About the kind of dispersing agent and complexing agent, and those density | concentrations, what was mentioned in description of the a1 process can be used by the density | concentration demonstrated in the a1 process.

  The nickel salt, reducing agent and alkali contained in the first and second aqueous solutions of (i) and the first to third aqueous solutions of (ii) are the same as those used for these aqueous solutions in step a2. Things can be used. The concentration of the nickel salt in the aqueous solution is preferably 10 to 1000 g / L, particularly 50 to 500 g / L. The concentration of the reducing agent is preferably 100 to 1000 g / L, particularly 100 to 800 g / L when a phosphorus compound is used as the reducing agent. When using a boron compound as a reducing agent, it is preferable that it is 5-200 g / L, especially 10-100 g / L. When hydrazine or a derivative thereof is used as the reducing agent, it is preferably 5 to 200 g / L, particularly 10 to 100 g / L. The alkali concentration is preferably 5 to 500 g / L, more preferably 10 to 200 g / L. In this manner, particles coated with the target smooth surface nickel or nickel alloy film are obtained.

  Although conductive particles in which nickel or a nickel alloy film is formed on the core material particles are obtained by the above-described method, they can be further subjected to post-treatment as necessary. Examples of the post-treatment include an electroless gold plating step or an electroless palladium plating step. By applying this step, a gold plating layer or a palladium plating layer is formed on the surface of the conductive particles. The gold plating layer can be formed according to a conventionally known electroless plating method. For example, by adding an electroless plating solution containing tetrasodium ethylenediaminetetraacetate, disodium citrate and potassium gold cyanide and adjusted to pH with sodium hydroxide to an aqueous suspension of conductive particles, A plating layer can be formed.

  Moreover, formation of a palladium plating layer can be performed in accordance with a conventionally well-known electroless plating method. For example, reduction of water-soluble palladium compounds such as palladium chloride; hypophosphorous acid, phosphorous acid, formic acid, acetic acid, hydrazine, borohydride, amine borane compounds, or salts thereof into an aqueous suspension of conductive particles A conventional electroless palladium plating solution containing an agent; and a complexing agent, and a dispersant, a stabilizer, and a pH buffering agent are added as necessary. Then, while adjusting the pH with an acid such as hydrochloric acid or sulfuric acid or a base such as sodium hydroxide, reduction type electroless plating can be performed to form a palladium plating layer. Alternatively, a palladium ion source such as tetraamminepalladium salt, a complexing agent and, if necessary, a dispersing agent are added to an aqueous suspension of conductive particles, and substitution is performed using a substitution reaction between palladium ions and nickel ions. A palladium electroplating layer may be formed by performing mold electroless plating.

  In addition, it is preferable that the palladium plating layer does not substantially contain phosphorus or has a content reduced to 3% by weight or less from the viewpoint of excellent conductivity and electrical reliability. In order to form such a plating layer, for example, when substitutional electroless plating is performed or when reducing electroless plating is performed, a phosphorus-free reducing agent (for example, formic acid) may be used.

  As the dispersant used in the reduction type electroless plating or the displacement type electroless plating, the same dispersants as exemplified in the above-described step a1 can be used. Moreover, as a common electroless palladium plating solution, you may use the commercial item available from Kojima Chemical Co., Ltd., Nippon Kanisen Co., Ltd., Chuo Chemical Industrial Co., Ltd., etc., for example.

  As another post-treatment, the conductive particles can be subjected to a pulverization step using a media mill such as a ball mill. By subjecting to this pulverization step, the weight occupied by the primary particles relative to the weight of the conductive powder can be further improved in combination with the above-described nickel ion reduction conditions.

  When the conductive particles of the present invention are used as a conductive filler of a conductive adhesive as will be described later, the surface of the conductive particles is further coated with an insulating resin in order to prevent the occurrence of short circuit between the conductive particles. can do. In this coating with an insulating resin, an insulating coating layer is formed so that the surface of the conductive particles is not exposed as much as possible without applying pressure or the like. For example, the conductive coating containing the conductive particles of the present invention is used. It is destroyed by heating and pressurizing when two substrates are bonded using an adhesive, and at least the surface of the conductive particles is exposed. The thickness of this insulating resin layer is usually about 0.1 to 0.5 μm. The insulating resin layer does not necessarily need to completely cover the surface of the conductive particles as long as the effect of providing the insulating coating layer is exhibited. From this viewpoint, for example, the insulating resin particles are coated with the conductive particles. It may be just attached to the surface of the film.

  As the insulating resin, those known in the art can be widely used. For example, phenol resin, urea resin, melamine resin, allyl resin, furan resin, polyester resin, epoxy resin, silicone resin, polyamide-imide resin, polyimide resin, polyurethane resin, fluorine resin, polyolefin resin (example: polyethylene) , Polypropylene, polybutylene), polyalkyl (meth) acrylate resin, poly (meth) acrylic acid resin, polystyrene resin, acrylonitrile-styrene-butadiene resin, vinyl resin, polyamide resin, polycarbonate resin, polyacetal resin, ionomer resin, polyethersulfone Mention may be made of resins, polyphenyl oxide resins, polysulfone resins, polyvinylidene fluoride resins, ethyl cellulose and cellulose acetate.

  As a method of forming an insulating coating layer on the surface of conductive particles, a chemical method such as a coacervation method, an interfacial polymerization method, an in situ polymerization method and a liquid curing coating method, a spray drying method, an air suspension coating method Physicochemical methods such as vacuum deposition coating method, dry blend method, hybridization method, electrostatic coalescence method, melt dispersion cooling method and inorganic encapsulation method, and interfacial precipitation method.

  The conductive particles of the present invention thus obtained are used for connecting, for example, an anisotropic conductive film (ACF), a heat seal connector (HSC), and an electrode of a liquid crystal display panel to a circuit board of a driving LSI chip. It is suitably used as a conductive material. In particular, the conductive particles of the present invention are suitably used as a conductive filler of a conductive adhesive.

  The conductive adhesive is preferably used as an anisotropic conductive adhesive that is disposed between two substrates on which a conductive base material is formed, and adheres and conducts the conductive base material by heating and pressing. . This anisotropic conductive adhesive contains the conductive particles of the present invention and an adhesive resin. Any adhesive resin can be used without particular limitation as long as it is insulative and used as an adhesive resin. Either a thermoplastic resin or a thermosetting resin may be used, and those that exhibit adhesive performance by heating are preferred. Examples of such an adhesive resin include a thermoplastic type, a thermosetting type, and an ultraviolet curing type. In addition, there are so-called semi-thermosetting types that exhibit intermediate properties between thermoplastic types and thermosetting types, combined types of thermosetting types and ultraviolet curing types, and the like. These adhesive resins can be appropriately selected according to the surface characteristics and usage pattern of the circuit board or the like to be attached. In particular, an adhesive resin including a thermosetting resin is preferable from the viewpoint of excellent material strength after bonding.

  Specific examples of the adhesive resin include ethylene-vinyl acetate copolymer, carboxyl-modified ethylene-vinyl acetate copolymer, ethylene-isobutyl acrylate copolymer, polyamide, polyimide, polyester, polyvinyl ether, polyvinyl butyral, and polyurethane. , SBS block copolymer, carboxyl-modified SBS copolymer, SIS copolymer, SEBS copolymer, maleic acid-modified SEBS copolymer, polybutadiene rubber, chloroprene rubber, carboxyl-modified chloroprene rubber, styrene-butadiene rubber, isobutylene- Isoprene copolymer, acrylonitrile-butadiene rubber (hereinafter referred to as NBR), carboxyl-modified NBR, amine-modified NBR, epoxy resin, epoxy ester resin, acrylic resin, phenol resin or Those obtained by one or more combinations selected from such recone resins those prepared as main agent. Of these, as the thermoplastic resin, styrene-butadiene rubber, SEBS, and the like are preferable because of their excellent reworkability. As the thermosetting resin, an epoxy resin is preferable. Of these, epoxy resins are most preferred because of their advantages of high adhesive strength, excellent heat resistance and electrical insulation, low melt viscosity, and connection at low pressure.

  As the epoxy resin, a generally used epoxy resin can be used as long as it is a polyvalent epoxy resin having two or more epoxy groups in one molecule. Specific examples include novolak resins such as phenol novolak and cresol novolak, polyhydric phenols such as bisphenol A, bisphenol F, bisphenol AD, resorcin, and bishydroxydiphenyl ether, ethylene glycol, neopentyl glycol, glycerin, and trimethylolpropane. Obtained by reacting polychlorohydric alcohols such as polypropylene glycol, polyamino compounds such as ethylenediamine, triethylenetetramine, and aniline, polycarboxyl compounds such as adipic acid, phthalic acid, and isophthalic acid with epichlorohydrin or 2-methylepichlorohydrin. A glycidyl type epoxy resin is exemplified. Moreover, aliphatic and alicyclic epoxy resins such as dicyclopentadiene epoxide and butadiene dimer epoxide are listed. These can be used alone or in admixture of two or more.

  In addition, it is preferable from the viewpoint of prevention of ion migration that the various adhesive resins described above use high-purity products in which impurity ions (such as Na and Cl) and hydrolyzable chlorine are reduced.

  The amount of the conductive particles of the present invention used in the anisotropic conductive adhesive is usually 0.1 to 30 parts by weight, preferably 0.5 to 25 parts by weight, more preferably 1 to 100 parts by weight of the adhesive resin component. ~ 20 parts by weight. When the amount of the conductive particles used is within this range, an increase in connection resistance and melt viscosity is suppressed, connection reliability is improved, and connection anisotropy can be sufficiently secured.

  In addition to the above-described conductive particles and adhesive resin, the anisotropic conductive adhesive can be blended with known additives in the technical field, and the blending amount is also known in the technical field. Can be within range. Other additives include, for example, tackifiers, reactive auxiliaries, epoxy resin curing agents, metal oxides, photoinitiators, sensitizers, curing agents, vulcanizing agents, deterioration inhibitors, heat resistant additives, heat Examples thereof include a conductivity improver, a softener, a colorant, various coupling agents, or a metal deactivator.

  Examples of the tackifier include rosin, rosin derivatives, terpene resins, terpene phenol resins, petroleum resins, coumarone-indene resins, styrene resins, isoprene resins, alkylphenol resins, xylene resins and the like. Examples of the reactive assistant, that is, the crosslinking agent include polyols, isocyanates, melamine resins, urea resins, utropines, amines, acid anhydrides and peroxides. As an epoxy resin hardening | curing agent, if it has two or more active hydrogens in 1 molecule, it can be especially used without a restriction | limiting. Specific examples include polyamino compounds such as diethylenetriamine, triethylenetetramine, metaphenylenediamine, dicyandiamide, and polyamideamine; organic acid anhydrides such as phthalic anhydride, methyl nadic anhydride, hexahydrophthalic anhydride, and pyromellitic anhydride. Products: novolak resins such as phenol novolac and cresol novolak. These can be used alone or in admixture of two or more. Moreover, you may use a latent hardening | curing agent as needed and a use. Examples of latent curing agents that can be used include imidazole series, hydrazide series, boron trifluoride-amine complexes, sulfonium salts, amine imides, polyamine salts, dicyandiamide, and the like and modified products thereof. These can be used alone or as a mixture of two or more.

  The anisotropic conductive adhesive is usually prepared by using a manufacturing apparatus widely used among those skilled in the art, and blends the conductive particles and adhesive resin of the present invention and, if necessary, curing agents and various additives, In the case where the adhesive resin is a thermosetting resin, by mixing in an organic solvent, in the case of a thermoplastic resin, at a temperature equal to or higher than the softening point of the adhesive resin, specifically preferably about 50 to 130 ° C, More preferably, it is produced by melt-kneading at about 60 to 110 ° C. The anisotropic conductive adhesive thus obtained may be applied or applied in the form of a film.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, this invention is not necessarily limited to these Examples.

<Preparation of core particle>
(Preparation of core particle sample 1)
(A) Step;
To 100 g of RO water, 10 g of methyltrimethoxysilane was added and stirred for 3 hours for hydrolysis. 1 mL of 1.0 M aqueous ammonia solution was added to the reaction solution, and the mixture was stirred for 1.5 hours for dehydration condensation. The particles made of polyorganosiloxane (a) thus obtained had an average particle size of 1.52 μm and a deviation coefficient of 4.0%.
(B) step;
To the reaction solution in step (A), 900 g of RO water was added and stirred so that the particles obtained in step (A) were uniformly dispersed. To the upper layer of the reaction solution, 40 g of vinyltrimethoxysilane was slowly added so that the interface between the two layers could be maintained. Stirring was continued after the addition was completed, and it took 3 hours for the upper layer to disappear and become one layer due to hydrolysis and dehydration condensation of vinyltrimethoxysilane. Further, the stirring was continued for about 1 hour.
Next, 5 mL of a 28 wt% aqueous ammonia solution was added to the reaction solution, and stirring was continued for 20 hours to complete the dehydration condensation reaction of particles composed of two types of polyorganosiloxane.
Next, stirring was stopped and the mixture was allowed to stand to precipitate the resulting particles, and then the ammonia-containing solution was removed. The obtained particles were filtered and thoroughly washed until the methanol used as the washing liquid became neutral, and then dried at 80 ° C. for 3 hours.
The average particle size of the resulting particles of the two types of polyorganosiloxane was 2.15 μm, and the deviation coefficient was 2.1%. Further, the ratio of the thickness of the part constituting the shell to the diameter of the part constituting the core was shell / core = 0.21.
(C) step;
The particles obtained in the step (B) were baked at 250 ° C. for 12 hours to obtain spherical core particle samples 1 in which the surface of the core particles made of polyorganosiloxane (a) was coated with silica.
The average particle diameter of the obtained core material particle sample 1 was 2.07 μm, and the deviation coefficient (CV value) was 2.1%. The ratio (T / D) of the thickness (T) of the polyorganosiloxane to the diameter (D) of the core silica particles was 0.18.

(Preparation of core particle sample 2)
(A) Step;
To 100 g of RO water, 10 g of methyltrimethoxysilane was added and stirred for 3 hours for hydrolysis. After adding 1 mL of 1.0 M aqueous ammonia solution to this reaction solution, it was stirred for 1.5 hours for dehydration condensation. The average particle diameter of the particles made of the polyorganosiloxane (a) was 1.70 μm, and the deviation coefficient was 3.4%.
(B) step;
To the reaction solution of step (A), 900 g of RO water was added and stirred so that the particles obtained in step (A) were uniformly dispersed in the solution. To the upper layer of this solution, 80 g of vinyltrimethoxysilane was slowly added so that the interface between the two layers could be maintained. Stirring was continued even after the addition was completed, and it took 5 hours for the upper layer to disappear and become one layer due to hydrolysis and dehydration condensation of vinyltrimethoxysilane. Further, the stirring was continued for about 1 hour.
Next, 5 mL of a 28 wt% aqueous ammonia solution was added to the reaction solution, and stirring was continued for 20 hours to complete the dehydration condensation reaction of particles composed of two types of polyorganosiloxane.
Next, stirring was stopped and the mixture was allowed to stand to precipitate the resulting particles, and then the ammonia-containing solution was removed. The obtained particles were filtered and thoroughly washed until the methanol used as the washing liquid became neutral, and then dried at 80 ° C. for 3 hours. The average particle diameter of the resulting particles of the two types of polyorganosiloxane was 3.08 μm, and the deviation coefficient was 1.9%. Moreover, the ratio of the thickness of the part which comprises a shell, and the diameter of the part which comprises a core was shell / core = 0.41.
(C) step;
The particles obtained in the step (B) were fired at 250 ° C. for 12 hours to obtain a spherical core particle sample 2.
The obtained core material particle sample 2 had an average particle diameter of 2.94 μm and a deviation coefficient (CV value) of 2.3%. The ratio (T / D) of the thickness (T) of the polyorganosiloxane to the diameter (D) of the core silica particles was 0.36.

<Preparation of comparative core particles>
(Preparation of core particle sample 3)
A commercially available spherical benzoguanamine resin having an average particle size of 3.0 μm was prepared as the core material particle sample 3.

(Preparation of core particle sample 4)
Commercially available silica particles having an average particle diameter of 3.0 μm were prepared as the core material particle sample 4.

[Example 1]
(Preprocessing)
Using the core particle sample 1 prepared above, 6.2 g thereof was added to 400 mL of an aqueous conditioner solution (“Cleaner Conditioner 231” manufactured by Rohm and Haas Electronic Materials) with stirring. The concentration of the aqueous conditioner solution was 40 mL / L. Subsequently, the core material particles were surface-modified and dispersed by stirring for 30 minutes while applying ultrasonic waves at a liquid temperature of 60 ° C. The aqueous solution was filtered and the core particles washed once with repulp water were made into 200 mL slurry. 200 mL of stannous chloride aqueous solution was thrown into this slurry. The concentration of this aqueous solution was 5 × 10 ⁻³ mol / L. The mixture was stirred at room temperature for 5 minutes to carry out a sensitization treatment for adsorbing tin ions on the surface of the core material particles. Subsequently, the aqueous solution was filtered and washed once with repulp water. The core particles were then made into 400 mL slurry and maintained at 60 ° C. While stirring the slurry using ultrasonic waves, 2 mL of a 0.11 mol / L palladium chloride aqueous solution was added. The state of stirring as it was was maintained for 5 minutes, and an activation treatment for capturing palladium ions on the surface of the core particles was performed.
(Electroless nickel plating treatment)
The pretreated core material particles are added to 3 L of an aqueous solution containing 20 g / L sodium tartrate and 5 g / L polyethylene glycol heated to 70 ° C. with stirring, and the aqueous slurry is sufficiently dispersed by stirring. It was adjusted. Next, 300 mL of a 224 g / L nickel sulfate aqueous solution (first aqueous solution) and a mixed aqueous solution (second aqueous solution) containing 210 g / L sodium hypophosphite and 80 g / L sodium hydroxide were added. The addition rate was 5 mL / min. After all the aqueous solutions were added to the aqueous slurry, stirring was continued for 5 minutes while maintaining a temperature of 70 ° C. Next, the liquid was filtered, and the filtrate was washed three times, followed by vacuum drying at 110 ° C. to obtain a film-coated particle sample with a nickel-phosphorus alloy coated on the surface.

[Example 2]
A film-coated particle sample having a surface coated with a nickel-phosphorus alloy was obtained in the same manner as in Example 1 except that 8.8 g of the core particle sample 2 was used.

Example 3
An electroless gold plating solution consisting of 10 g / L EDTA-4Na, 10 g / L citric acid-2Na and 2.9 g / L potassium gold cyanide (2.0 g / L as Au) was prepared. While heating 2 L of this gold plating solution to 79 ° C. and stirring it, 9 g of the nickel-coated particle sample obtained in Example 1 was added. Thus, electroless plating treatment was performed on the surface of the particles. The processing time was 20 minutes. After completion of the treatment, the liquid was filtered and the filtrate was repulped three times. Subsequently, it dried with the 110 degreeC vacuum dryer. In this way, a gold plating coating treatment was performed on the nickel-phosphorus alloy film.

Example 4
The nickel-phosphorus alloy film was subjected to gold plating coating treatment in the same manner as in Example 3 except that 10.5 g of the nickel-coated particle sample obtained in Example 2 was used.

Example 5
10 g / L EDTA-2Na, 10 g / L citric acid-2Na and 20 g / L tetraamminepalladium hydrochloride (Pd (NH ₃ ) ₄ Cl ₂ ) solution (2 g / L as palladium), carboxymethylcellulose (molecular weight 250,000, An electroless palladium plating solution consisting of 100 ppm of etherification degree 0.9) was prepared. 1.2 L of this palladium plating solution was heated to 70 ° C. While stirring this, 8.7 g of the nickel-coated particle sample obtained in Example 1 was added. Thus, electroless plating treatment was performed on the surface of the particles. The processing time was 60 minutes. After completion of the treatment, the liquid was filtered and the filtrate was repulped three times. Subsequently, it dried with the 110 degreeC vacuum dryer. In this way, the palladium plating coating treatment was performed on the nickel-phosphorus alloy film.

Example 6
A nickel-phosphorus alloy film was subjected to a palladium plating coating treatment in the same manner as in Example 5 except that 10.2 g of the nickel-coated particle sample obtained in Example 2 was used.

[Comparative Example 1]
A coating with a nickel-phosphorus alloy coated in the same manner as in Example 1 except that 9 g of the core particle sample 3 was used and that the first aqueous solution and the second aqueous solution to be added were 240 mL each. A particle sample was obtained.

[Comparative Example 2]
Gold plating was applied onto the nickel-phosphorus alloy film in the same manner as in Example 3 except that 8.7 g of the nickel-coated particle sample obtained in Comparative Example 1 was used and that the gold plating solution was 1.5 L. A coating treatment was applied.

[Comparative Example 3]
Palladium plating on the nickel-phosphorus alloy film was performed in the same manner as in Example 5 except that 8.4 g of the nickel-coated particle sample obtained in Comparative Example 1 was used and that the palladium plating solution was 0.9 L. A coating treatment was applied.

[Comparative Example 4]
Coating film coated with nickel-phosphorous alloy in the same manner as in Example 1 except that 9 g of the core particle sample 4 was used and that the first aqueous solution and the second aqueous solution to be added were each 170 mL. A particle sample was obtained.

[Comparative Example 5]
Gold plating on the nickel-phosphorus alloy film was carried out in the same manner as in Example 3 except that 6.9 g of the nickel-coated particle sample obtained in Comparative Example 4 was used and that the gold plating solution was 1.0 L. A coating treatment was applied.

[Comparative Example 6]
Palladium plating on the nickel-phosphorus alloy film was carried out in the same manner as in Example 5 except that 6.6 g of the nickel-coated particle sample obtained in Comparative Example 4 was used and that the palladium plating solution was 0.6 L. A coating treatment was applied.

<Evaluation of physical properties of conductive particles>
(1) Thickness of metal film About the electroconductive particle obtained by the Example and the comparative example, the thickness of the metal film was measured by the following method.
[Thickness of nickel coating]
The conductive particles were immersed in aqua regia to dissolve the nickel coating, the coating components were analyzed by ICP or chemical analysis, and the thickness of the nickel coating was calculated from the following formulas (2) and (3).
A = [(r + t) ³ −r ³ ] d ₁ / r ³ d ₂ (2)
A = W / (100-W) (3)
In the formula, r is the radius (μm) of the core particles, t is the thickness of the nickel coating, d ₁ is the specific gravity of the nickel coating, d ₂ is the specific gravity of the core particles, and W is the nickel content (% by weight).

[Gold film / palladium film thickness]
Immerse the conductive particles in aqua regia, dissolve the gold or palladium film and nickel film, analyze the film components by ICP or chemical analysis, and calculate the thickness of the gold or palladium film from the following formulas (4) and (5). did.
B = [(r + t + u) ³ ] − (r + t) ³ ] d ₃ / (r + t) ³ d ₄ (4)
B = X / (100-X) (5)
In the formula, u is the thickness of the gold or palladium film, d ₃ is the specific gravity of the gold or palladium film, d ₄ is the specific gravity of the nickel-plated particles, and X is the content (% by weight) of gold or palladium. The specific gravity of the nickel plating particles was calculated by the following formula (6).
d ₄ = 100 / [(W / d ₁ ) + (100−W) / d ₂ ] (6)

(2) Adhesiveness of plating film The conductive particles 2.2g of Example 1, Example 2, Comparative Example 1, and Comparative Example 4 and 90 g of zirconia beads having a diameter of 3 mm were placed in a 100 mL mayonnaise bottle. Furthermore, 10 mL of toluene was added to the mayonnaise bottle using a whole pipette. The inside of the mayonnaise bottle was stirred for 10 minutes at 400 rpm using a stirrer (three one motor). After completion, the plating powder and zirconia beads were separated.
The plating powder was observed with a scanning electron microscope, and the peeling degree of the plating film was evaluated according to the following criteria.
○: Peeling of the plating film was not observed.
X: Peeling of the plating film was observed.

(3) Evaluation of conductivity The conductivity of the conductive particles obtained in Examples and Comparative Examples was evaluated by the following method. The results are shown in Table 2.

  100 parts of epoxy resin, 150 parts of curing agent, and 70 parts of toluene were mixed to prepare an insulating adhesive. This was mixed with 15 parts of conductive particles to obtain a paste. This paste was applied onto a silicone-treated polyester film and dried using a bar coater. The obtained coating film was used to connect between a glass whose front surface was vapor-deposited with aluminum and a polyimide film substrate having a copper pattern formed on a 50 μm pitch. And the electroconductivity of electroconductive particle was evaluated by measuring the conduction | electrical_connection resistance between electrodes. In the evaluation, a resistance value of 2Ω or less was evaluated as ◯, 2-5Ω was evaluated as Δ, and 5Ω or more was evaluated as ×.

  From the results in Table 2, it can be seen that the conductive particles of the present invention are superior in conductivity compared to conventional conductive particles. Moreover, since it is excellent also in plating adhesiveness, the connection reliability between electrodes can be improved more.

  The conductive particles of the present invention have high conductivity. Therefore, when the conductive particles of the present invention are used, for example, as a conductive material for an anisotropic conductive film or anisotropic conductive paste, such a conductive film or conductive paste can be obtained having high conductivity.

DESCRIPTION OF SYMBOLS 1; Core material particle 2; Core particle 3 which consists of polyorganosiloxane (a); Silica coating layer

Claims (6)

Conductive particles having a spherical core material particle and a conductive layer made of a metal film covering the core material particle, wherein the core particle is made of polyorganosiloxane (a) and the surface of the core particle is coated with silica. Conductive particles, wherein the ratio of the thickness of the silica coating layer to the diameter of the core particles made of the polyorganosiloxane (a) is 0.07 to 1.5.   The conductive particles according to claim 1, wherein the metal film is a nickel or nickel alloy film.   The conductive particles according to claim 2, further comprising a gold or palladium film on the nickel or nickel alloy film. It is a manufacturing method of the electroconductive particle of Claim 1, Comprising:
The polyorganosiloxane (a) is the decomposition temperature of the organic component on the particle surface of the core particles composed of the polyorganosiloxane (a) obtained by subjecting the alkoxysilane to a dehydration condensation reaction at -10 ° C to 60 ° C for 1 hour or more. And core-shell particles having a shell layer made of polyorganosiloxane (b) having a lower decomposition temperature of organic components than polyorganosiloxane (a) are prepared, and then the core-shell particles are contained in polyorganosiloxane (b). Heat treatment is performed at a temperature higher than the decomposition temperature of the organic component and lower than the decomposition temperature of the organic component contained in the polyorganosiloxane (a) to obtain core material particles, and then a conductive layer is formed on the particle surface of the core material particles. Forming a conductive particle.   5. The conductive material according to claim 4, wherein the polyorganosiloxane (a) is a hydrolysis condensate of methyltrimethoxysilane, and the polyorganosiloxane (b) is a hydrolysis condensate of vinyltrimethoxysilane. Method for producing particles.   The electroconductive material characterized by including the electroconductive particle of any one of Claims 1 thru | or 3.

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