JP2015199970A - Silver coated spherical resin particle, method for manufacturing the same, and conductive composition using silver coated spherical resin particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silver coated spherical resin particle capable of enhancing the adhesion of a silver coating to a spherical resin particle to improve conductivity, a method for manufacturing the same, and a conductive composition using the silver coated spherical resin particle.SOLUTION: The silver coated spherical resin particle comprises: a spherical acrylic, phenol or styrene resin particle; and a silver coated layer consisting of an aggregate of silver particles formed on the surfaces of the spherical resin particle. The amount of silver included in the silver coated layer is 2-80 pts.mass to the silver coated spherical resin particles of 100 pts.mass. The spherical resin particle has a roughened surface, and silver particles constituting a silver coated layer contacted with the surface of the spherical resin particle out of the silver coated layer are entered into the roughened surface of the spherical resin particle.

Description

  The present invention relates to a silver-coated spherical resin particle having improved adhesion by further improving the adhesion between the spherical resin particle and a silver coating, a method for producing the same, and a conductive composition using the silver-coated spherical resin particle.

  Conductive adhesives are being studied as alternative materials for lead solder. The conductive adhesive is a mixture of resin and metal conductive particles, and representative examples include a conductive film and a conductive paste. The conductive film and the conductive paste are excellent in workability such as stress absorption, low-temperature mounting, fine pitch conduction, insulation and no use of flux, and have been used for connecting electrodes of liquid crystal displays, touch panel substrates, keyboards and the like. In order to make it easier to use such conductive films and conductive pastes, metal-coated resin particles in which resin particles are coated with metal have been developed as conductive particles. Such metal-coated resin particles have the advantage of reducing manufacturing costs and weight. As the metal-coated resin particles, there is disclosed a conductive electroless plating powder in which nickel is electrolessly plated on resin particles and gold is coated on the upper surface (see, for example, Patent Document 1). This conductive electroless plating powder is said to provide high conductive performance by Ni or Ni-Au coating as a plating layer being firmly adhered to resin particles as a substrate. On the other hand, conductive particles are disclosed in which the resin particles are subjected to a catalyst treatment (pretreatment) with tin, and then subjected to silver electroless plating to improve adhesion (see, for example, Patent Document 2).

JP 08-31655 A (Claim 1, paragraphs [0015] and [0016]) International Publication No. 2012/023566 (paragraphs [0010], [0020])

  In the method of Patent Document 1, when a Ni—Au multilayer coating is formed on resin particles, the adhesion between the resin particles and gold is achieved by electroless plating of gold after nickel electroless plating on the resin particles. Has improved. However, in this method, nickel plating and gold plating must be performed, and the plating process is complicated, and materials, base materials, and time are required. On the other hand, in the method of Patent Document 2, after pre-treating with tin and providing a tin adsorption layer on the surface of the spherical resin, the electroless plating of silver is performed to improve the adhesion of the silver coating. Adhesion was not sufficient. For example, when a high shearing force is applied to the paste to produce a conductive paste, the silver plating may be peeled off, leading to a decrease in conductivity. In the case of an anisotropic adhesive, the peeled-off plating piece becomes a foreign substance, which may enter a gap that should be insulated and cause a malfunction.

  An object of the present invention is to provide a silver-coated spherical resin particle having improved adhesion by further improving the adhesion between the spherical resin particle and the silver coating, a method for producing the same, and a conductive composition using the silver-coated spherical resin particle. There is.

  When the present inventors roughen the surface of the spherical resin particles and form a tin adsorption layer, and then perform electroless plating of silver, the silver crystal particles of small diameter (hereinafter simply referred to as particles) are roughened. A first layer coating is formed by entering into the dents on the surface of the spherical resin particles, and then the further grown large-diameter particles are laminated on the first layer coating to form the second layer coating, The present invention was completed by finding that silver-coated spherical resin particles characteristic of such silver coating can be produced.

  Based on FIG. 1, the mechanism that further improves the adhesion of the present invention compared to the conventional example will be described. FIG. 1B is a diagram schematically showing conventional silver-coated spherical resin particles 200. The surface of the spherical resin particle 201 is smooth, and no dent is generated on the surface. First, small-diameter silver particles grow on the surface of the spherical resin particles 201 by electroless plating. Subsequently, large-diameter silver particles grow on the upper surface of the first silver layer 202 made of small-diameter silver particles by electroless plating to form a second silver layer 203.

  Fig.1 (a) is the figure which showed typically the silver covering spherical resin particle 100 of this invention. In the present invention, the surface of the spherical resin particles is roughened to form a dent, and silver is electrolessly plated, so that small-diameter silver particles that crystallize in the initial stage of silver electroless plating enter the dent and grow. A first silver layer 102 is formed. On the upper surface of the silver layer 102, a dent slightly shallower than the dent on the roughened surface of the spherical resin particles is formed. Subsequently, silver particles of a size corresponding to the dent are laminated. Then, by continuing electroless plating, the dent is flattened, and silver particles having a larger diameter than the size of the dent are stacked, and a second silver layer 103 is formed. Whereas the conventional first silver layer 202 is formed on the smooth surface of the spherical resin particles 201, the first silver layer 102 of the present invention is formed by roughening the spherical resin particles 101. Therefore, the concealability is enhanced by the second silver layer 103 made of large-diameter particles, and the conductivity is improved.

  A first aspect of the present invention includes an acrylic, phenolic, or styrene spherical resin particle, and a silver coating layer made of an aggregate of silver particles formed on the surface of the spherical resin particle. In the silver-coated spherical resin particles in which the amount of silver contained in the layer is 2 to 80 parts by mass with respect to 100 parts by mass of the silver-coated spherical resin particles, the spherical resin particles have a roughened surface, Among them, the silver particles constituting the silver coating layer in contact with the surface of the spherical resin particles are characterized by entering the roughened surface of the spherical resin particles.

  A second aspect of the present invention is an invention based on the first aspect, wherein the average particle diameter of the silver particles entering the roughened surface of the spherical resin particles is in the range of 10 to 50 nm, and the spherical resin particles The average particle diameter of the silver particles that do not enter the roughened surface is silver-coated spherical resin particles in the range of 100 to 1000 nm.

  According to a third aspect of the present invention, an addition step of adding acrylic, phenolic, or styrene-based spherical resin particles to an aqueous tin compound solution kept at 25 to 45 ° C., and an aqueous tin compound solution In a method for producing silver-coated spherical resin particles comprising a step of performing electroless plating using a reducing agent, and a step of performing electroless plating of silver after the electroless plating of tin, a spherical resin is added before the adding step. It is a manufacturing method of the silver covering spherical resin particle which has the roughening process process which roughens the particle | grain surface of particle | grains.

  A fourth aspect of the present invention is the silver-coated spherical resin particle according to the third aspect, wherein the roughening treatment is a plasma treatment, ozone treatment or heat treatment at a temperature of 80 to 200 ° C. of the spherical resin particles. It is a manufacturing method.

  According to a fifth aspect of the present invention, a silver-coated spherical resin particle based on the first or second aspect or a silver-coated spherical resin particle produced by a method based on the third or fourth aspect and a binder are mixed. This is a method for producing an anisotropic conductive paste.

  According to a sixth aspect of the present invention, the silver-coated spherical resin particles based on the first or second viewpoint or the silver-coated spherical resin particles produced by the method based on the third or fourth aspect and a binder are mixed. To produce an anisotropic conductive film adhesive.

  According to a seventh aspect of the present invention, the silver-coated spherical resin particles based on the first or second aspect or the silver-coated spherical resin particles produced by the method based on the third or fourth aspect and a binder are mixed. Is a method for producing an isotropic conductive paste.

  According to an eighth aspect of the present invention, the silver-coated spherical resin particles based on the first or second aspect or the silver-coated spherical resin particles produced by the method based on the third or fourth aspect and a binder are mixed. Is a method for producing an isotropic conductive film adhesive.

  In the silver-coated spherical resin particles according to the first aspect of the present invention, the spherical resin particles have a roughened surface, and the silver particles constituting the silver coating layer in contact with the surface of the spherical resin particles in the silver coating layer are spherical. Since it has penetrated into the roughened surface of the resin particles, the adhesion and concealment of the silver coating layer are further increased, and the conductivity is improved. Moreover, since the thickness of the silver coating layer can be reduced, the manufacturing cost can be reduced.

  In the silver-coated spherical resin particles of the second aspect of the present invention, the average particle diameter of the silver particles entering the roughened surface of the spherical resin particles is in the range of 10 to 50 nm, and the spherical resin particles are roughened. The average particle diameter of the silver particles that do not enter the surface is in the range of 100 to 1000 nm. As a result, the first silver layer enters into the dents on the surface of the spherical resin particles formed by roughening, so that the adhesion of the silver coating layer is further increased, and the second silver layer has a surface hiding property. Therefore, the conductivity is improved.

  In the method for producing silver-coated spherical resin particles according to the third aspect of the present invention, an addition step of adding acrylic, phenolic, or styrene-based spherical resin particles to an aqueous solution of a tin compound kept at 25 to 45 ° C. Since the surface of the spherical resin particles has a roughening treatment step before the step, the silver-coated spherical resin particles can be produced by a method for producing silver-coated spherical resin particles. Coated spherical resin particles can be obtained.

  In the fourth aspect of the present invention, the surface of the spherical resin particles is reliably secured by the method for producing silver-coated spherical resin particles in which the roughening treatment is plasma treatment, ozone treatment or heat treatment at a temperature of 80 to 200 ° C. It is possible to obtain silver-coated spherical resin particles that can be roughened, have higher adhesion of the silver coating layer, and have improved conductivity.

  The anisotropic conductive paste produced by the method according to the fifth aspect of the present invention is excellent in conductivity.

  The anisotropic conductive film adhesive manufactured by the method based on the 6th viewpoint of this invention is excellent in electroconductivity.

  The isotropic conductive paste produced by the method according to the seventh aspect of the present invention is excellent in conductivity.

  The isotropic conductive film adhesive produced by the method according to the eighth aspect of the present invention is excellent in conductivity.

FIG. 1A schematically shows a silver coating layer formed on the surface of the spherical resin particle of the present invention, and FIG. 1B schematically shows a silver coating layer formed on the surface of the conventional spherical resin particle. It is. FIG. 2A is a transmission electron micrograph of a cross section of silver-coated spherical resin particles each showing a silver coating layer formed on the surface of the spherical resin particles of the example at a scale of 50 nm and FIG. 2B is a scale of 20 nm. FIG. FIG. 3A is a transmission electron micrograph of a cross section of silver-coated spherical resin particles each showing a silver coating layer formed on the surface of a spherical resin particle of a comparative example at a scale of 50 nm and FIG. 3B is a scale of 20 nm. FIG.

  Next, the form for implementing this invention is demonstrated.

  First, the silver-coated spherical resin particles of this embodiment will be described. The silver-coated spherical resin particles of the present embodiment include spherical resin particles, a surface roughened to the spherical resin particles, and an inner silver coating layer coated with silver particles that enter the roughened surface; An outer silver coating layer and inner and outer silver coating layers are provided. Silver is contained in an amount of 2 to 80 parts by mass with respect to 100 parts by mass of the silver-coated spherical resin particles. The silver particles may have an intermediate layer between the inner layer and the outer layer. In this case, the average particle diameters of the inner layer, the intermediate layer, and the outer layer are 10 to 50 nm, 50 to 100 nm, and 100 to 1000 nm, respectively. In addition, tin is adsorbed on the surface of the spherical resin particles by a tin adsorption process in the manufacturing process. The adsorbed tin layer undergoes a substitution reaction of tin and silver in the initial stage of electroless plating, and after completion of the substitution reaction, silver is coated by an electroless plating reaction with a reducing agent. Therefore, almost all of the tin is replaced with silver and does not remain in the silver-coated spherical resin particles.

  The spherical resin particles are preferably closer to a spherical shape, but may have some irregularities larger than the roughened dents on the surface of the elliptical particles or particles. However, if there are sharp protrusions, the silver-coated spherical resin particles are made isotropically conductive by reducing the adhesion of the plating coating when plated, and by reducing the dispersibility in the binder when mixed with a binder that is a resin. This is not preferable because it causes a loss of conductivity and insulation when used as a paste or anisotropic conductive paste. The ratio of the major axis to the minor axis of the spherical resin particles is preferably in the range of 1 to 1.5, more preferably in the range of 1 to 1.3, and still more preferably in the range of 1 to 1.1.

  Spherical resin particles that are required when silver-coated spherical resin particles are used in anisotropic conductive film adhesives, anisotropic conductive pastes, etc., when spherical resin particles are subjected to a load due to load The resin of the spherical resin particles is preferably made of acrylic, phenolic, or styrene from the viewpoint of the recovery rate when the crushing and the load are unloaded. Acrylic resin such as methyl methacrylate resin (PMMA resin), modified acrylic resin, phenolic resin as phenol resin, phenol / formaldehyde resin, phenol / furfural resin, styrene resin as polystyrene resin, styrene / acrylonitrile Examples thereof include polymers and ABS resins.

  The average particle size of the spherical resin particles is desirably in the range of 0.5 to 40 μm. Moreover, the variation coefficient of the particle diameter of the spherical resin particles is 6.0% or less, and it is preferable that the particle diameters are uniform. When the average particle diameter of the spherical resin particles is smaller than 0.5 μm, the surface area of the spherical resin particles becomes large, and it is necessary to increase silver for obtaining the necessary conductivity as the conductive particles. When the average particle diameter of the spherical resin particles is larger than 40 μm, it is difficult to apply the silver-coated spherical resin particles to the fine pattern. Further, if the particle diameters are not uniform, reproducibility of conductivity imparting when used as conductive particles may be impaired. For this reason, the variation coefficient of the particle diameter of the silver-coated spherical resin particles is 6.0% or less, and it is more preferable that the particle diameters are uniform.

  By the tin adsorption treatment described above, divalent ions of tin are adsorbed on the surface of the spherical resin particles. The divalent ions of tin are dissolved as tetravalent ions and emit divalent electrons. Then, silver ions receive electrons and deposit on the portion where the tin of the spherical resin particles was adsorbed as a metal. Thereafter, when all divalent ions of tin are converted to tetravalent ions and dissolved in the aqueous solution, the substitution reaction of tin and silver is completed, the catalyst is oxidized by the reducing agent, electrons are released, and the silver ions in the solution are The electrons are received and silver is deposited. A silver coating layer is formed by the above substitution reaction and reduction reaction.

  The average particle diameter of the silver particles was observed with a transmission electron microscope and the cross-sectional shape was observed. The surface of the spherical resin particles of a plurality of samples was in the range of 2000 nm. The particle diameter of was measured visually. The average value of the particle diameter was calculated between the layers in which the particle diameter changed for each sample.

  The coating amount (content) of silver is determined by the average particle size of the resin and the required conductivity. When the silver content is less than 2 parts by mass with respect to 100 parts by mass of the silver-coated spherical resin particles, when the silver-coated spherical resin particles are dispersed as the conductive particles, it is difficult to obtain a contact point between the silver particles. Cannot be granted. On the other hand, if the silver content is greater than 80 parts by mass, the specific gravity increases, the cost increases, and the conductivity is saturated. The silver content is preferably 28 to 70 parts by mass, more preferably 28 to 60 parts by mass.

As for the conductivity of the silver-coated spherical resin particles of this embodiment, the powder volume resistivity is preferably 1 × 10 ⁻² Ω · cm or less, and more preferably 3 × 10 ⁻³ Ω · cm or less. If the powder volume resistivity is higher than 1 × 10 ⁻² Ω · cm, the loss due to the voltage drop of the material increases, which is not suitable as a conductive material. The powder volume resistivity is obtained by measuring the resistance value of a green compact obtained by putting silver-coated spherical resin particles, which are sample powder, into a pressure vessel and compressing at 9.8 MPa with a resistivity meter.

  Next, a conductive adhesive in which silver-coated spherical resin particles (conductive particles, filler) and a binder (adhesive) are mixed will be described. There exist isotropic conductive adhesive (ICA: Isotropic Conductive Adhesive) and anisotropic conductive adhesive (ACA: Anisotropic Conductive Adhesive) in conductive adhesive. Also, there are pastes, films, and inks depending on the form of the binder. In the isotropic conductive adhesive, the binder contracts when the binder is cured, so that the filler comes into contact with each other and the conductive material to be connected and the filler come into contact with each other to obtain conductivity. It is also possible to form a sheet with an isotropic conductive adhesive. An anisotropic conductive adhesive is a filler between conductive materials to be connected by pressurizing the anisotropic conductive adhesive between the conductive materials to be connected with filler dispersed in the binder. Conductive material desired to be connected to contact with each other to obtain conductivity. On the other hand, the non-pressurized portion is incapable of obtaining conductivity because the fillers are dispersed through the insulating binder and do not contact each other.

  The anisotropic conductive paste adhesive and the anisotropic conductive film adhesive are prepared by mixing the silver-coated spherical resin particles and the binder of the present embodiment with 0.1 part by weight of silver-coated spherical resin particles with respect to 100 parts by mass of the binder. It is prepared by containing 5 to 5 parts by mass. The isotropic conductive paste adhesive and the isotropic conductive film adhesive are prepared by mixing the silver-coated spherical resin particles and the binder of this embodiment with the silver-coated spherical resin particles for 100 parts by mass of the binder. It is prepared by containing 150 to 250 parts by mass.

  An epoxy resin-based bisphenol A type epoxy resin or bisphenol F type epoxy resin is added to the binder as an amine-based dicyandiamide or isoidal as a thermosetting curing agent. Other binders used for inks and pastes include styrene-butadiene block copolymers, thermoplastic resins such as acrylate resins and ethylene-vinyl acetate resins, glycidyl group-containing monomers and oligomers, and curing agents such as isocyanates. And a curable resin composition such as a resin composition. Examples of the binder used for the film include a resin composition containing a thermosetting resin such as the epoxy resin-based phenoxy resin as a main component.

  Next, a method for producing silver-coated spherical resin particles will be described. The surface of the spherical resin particles is roughened and then tin is adsorbed on the surface. Next, electroless silver plating is performed to produce silver-coated spherical resin particles.

  First, the spherical resin particles are roughened. As the spherical resin particles, acrylic, phenol and styrene spherical resin particles are used. In addition, for example, spherical resin particles such as styrene, silicone, urethane, epoxy, Teflon (trademark), and melamine can be used.

  The spherical resin particles are subjected to plasma treatment in an oxygen atmosphere, ozone treatment, and heat treatment in an atmosphere having a temperature of 80 to 200 ° C. as a treatment for roughening the surface. It is considered that the surface of the spherical resin particles is oxidized by this treatment. In addition, the surface is roughened by humidification, heat treatment in vacuum, pressurization, heat treatment under humidification conditions, wet treatment with an oxidizing agent, or the like. Examples of the oxidizing agent include hydrogen peroxide, hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, and chromic acid. In addition, wet treatment with an oxidizing agent may be combined with plasma treatment, ozone treatment, heat treatment, and humidification treatment. In addition, the surface of the spherical resin particles is roughened not only by treatment by oxidation, but by physical treatment, for example, plasma treatment in a vacuum atmosphere or air atmosphere, grinding treatment by a ball mill, etc. As long as it is a process to do. Tin is introduced into the surface roughened by the roughening treatment by the next tin adsorption treatment. Next, by performing electroless plating of silver to replace tin and silver, a silver coating layer that does not peel off can be plated even when a high shear force is finally applied. Thereby, when the silver covering spherical resin particle of this invention is used for an anisotropic conductive adhesive, for example, the short circuit of anisotropic conductivity can be avoided and reliability improves.

  Next, tin adsorption treatment is performed. In the tin adsorption treatment, spherical resin particles are added to an aqueous solution of a tin compound and stirred. Then, the spherical resin particles are separated by filtration and washed with water. Although stirring time is suitably determined by the temperature of the following aqueous solution of a tin compound and the content of the tin compound, it is preferably 0.5 to 24 hours. The temperature of the tin compound aqueous solution is in the range of 25 to 45 ° C. Preferably it is 25-40 degreeC, Most preferably, it is 27-40 degreeC. When the temperature of the aqueous solution of the tin compound is higher than 45 ° C., the tin compound is oxidized, so that the aqueous solution becomes unstable and the tin compound does not sufficiently adhere to the spherical resin particles. By carrying out this tin adsorption treatment with an aqueous solution at 25 to 45 ° C., silver is electrolessly plated with a reducing agent alone, and fine particles of resin such as acrylic resin, phenol resin, styrene resin, etc., which have poor adhesion. In contrast, tin and silver that are sufficiently adsorbed in the initial stage in the electroless plating process described below are substituted, so that the substituted silver can be brought into close contact with the surface of the resin.

Examples of tin compounds used in the tin adsorption treatment include stannous chloride, stannous fluoride, stannous bromide, and stannous iodide. When stannous chloride is used, the content of stannous chloride in the aqueous solution of the tin compound is preferably ³⁰ to 100 g / dm ³ . If the stannous chloride content is 30 g / dm ³ or more, a uniform tin coating can be formed on the surface of the spherical resin particles. Moreover, it is easy to suppress the amount of inevitable impurities in stannous chloride when the content of stannous chloride is 100 g / dm ³ or less. Note that stannous chloride can be contained in an aqueous solution of a tin compound until saturation.

The aqueous solution of the tin compound preferably contains 0.5 to 2 cm ^{3 of} hydrochloric acid with respect to 1 g of stannous chloride. When the amount of hydrochloric acid is 0.5 cm ³ or more, the solubility of stannous chloride is improved and the hydrolysis of tin can be suppressed. When the amount of hydrochloric acid is 2 cm ³ or less, the pH of the tin compound aqueous solution does not become too low, so that tin can be efficiently adsorbed on the spherical resin particles.

Next, electroless plating of silver is performed. Any of the following three methods can be applied as the electroless plating method.
(1) A method in which spherical resin particles after roughening treatment and tin adsorption treatment are immersed in an aqueous solution containing a complexing agent and a reducing agent, and an aqueous silver salt solution is dropped.
(2) A method in which spherical resin particles after roughening treatment and tin adsorption treatment are immersed in an aqueous solution containing a silver salt and a complexing agent, and an aqueous reducing agent solution is dropped.
(3) A method in which spherical resin particles after the surface roughening treatment and tin adsorption treatment are immersed in an aqueous solution containing a silver salt, a complexing agent, and a reducing agent, and a caustic aqueous solution is dropped.

  Silver nitrate or silver dissolved in nitric acid can be used as the silver salt. As the complexing agent, salts such as ammonia, ethylenediaminetetraacetic acid, tetrasodium ethylenediaminetetraacetic acid, nitrotriacetic acid, triethylenetetraamminehexaacetic acid can be used. As the reducing agent, formalin, glucose, Rochelle salt (sodium potassium tartrate), hydrazine and its derivatives can be used. In particular, formaldehyde which is an aqueous solution of formalin is preferable, a mixture of two or more reducing agents including at least formaldehyde is more preferable, and a mixture of reducing agents including formaldehyde and glucose is most preferable.

  Next, examples of the present invention will be described in detail together with comparative examples.

<Example 1>
For tin adsorption treatment, an aqueous solution in which 15 g of stannous chloride and 15 cm ³ of 35% hydrochloric acid was diluted to 1 dm ³ with water using a 1 dm ³ volumetric flask was stored at 27 ° C.

For electroless plating, 228 g of ethylenediaminetetraacetic acid tetrasodium (complexing agent), 53 g of sodium hydroxide, 105 cm ³ of formalin are dissolved in 2 dm ³ of water, and an aqueous solution containing the complexing agent and reducing agent is prepared. Produced. Further, 35 g of silver nitrate, 53 cm ³ of 25% aqueous ammonia, and 175 cm ³ of water were mixed to prepare an aqueous solution containing silver nitrate.

  As a roughening treatment of the surface of the spherical resin particles, a spherical resin particle made of acrylic resin (PMMA cross-linked beads) having a particle diameter of 20 μm is applied to an ozone generator (model ozone super ace, manufactured by Nippon Ozone Generator Co., Ltd.) with a gas concentration of 2 vol%. The ozone treatment was performed by blowing with ozone gas for 30 minutes. After cooling, 41 g of spherical resin particles after the roughening treatment were added to the aqueous solution for tin adsorption treatment, and the mixture was stirred at a temperature of 30 ° C. for 1 hour. Thereafter, the spherical resin particles were separated by filtration and washed with water. Next, the spherical resin particles subjected to tin adsorption treatment are immersed in the aqueous solution containing the complexing agent and the reducing agent, and the aqueous solution containing silver nitrate is dropped while stirring the aqueous solution, and the spherical resin particles are coated with silver to form silver. Coated spherical resin particles were obtained. The silver coating amount was 35 parts by mass with respect to 100 parts by mass of the silver-coated spherical resin particles.

<Example 2>
For tin adsorption treatment, an aqueous solution in which 15 g of stannous chloride and 15 cm ³ of 35% hydrochloric acid was diluted to 1 dm ³ with water using a 1 dm ³ volumetric flask was stored at 27 ° C.

For electroless plating, 228 g of ethylenediaminetetraacetic acid tetrasodium (complexing agent), 53 g of sodium hydroxide, 105 cm ³ of formalin are dissolved in 2 dm ³ of water, and an aqueous solution containing the complexing agent and reducing agent is prepared. Produced. Further, 35 g of silver nitrate, 53 cm ³ of 25% aqueous ammonia, and 175 cm ³ of water were mixed to prepare an aqueous solution containing silver nitrate.

As a roughening treatment on the surface of the spherical resin particles, spherical resin particles made of acrylic resin (PMMA cross-linked beads) with a particle diameter of 15 μm are loaded into the reaction chamber of a plasma generator (model YHS-G type, manufactured by Sakai Semiconductor Co., Ltd.). The degree of vacuum in the reaction chamber was 20 Pa. Next, oxygen gas was fed into the reaction chamber at a constant rate of 15 cm ³ per minute, and 20 W of power was applied to generate plasma for 30 minutes. After cooling, 41 g of spherical resin particles after the roughening treatment were added to the aqueous solution for tin adsorption treatment, and the mixture was stirred at a temperature of 35 ° C. for 1 hour. Thereafter, the spherical resin particles were separated by filtration and washed with water. Next, the spherical resin particles subjected to tin adsorption treatment are immersed in the aqueous solution containing the complexing agent and the reducing agent, and the aqueous solution containing silver nitrate is dropped while stirring the aqueous solution, and the spherical resin particles are coated with silver to form silver. Coated spherical resin particles were obtained. The silver coating amount was 35 parts by mass with respect to 100 parts by mass of the silver-coated spherical resin particles.

<Example 3>
For tin adsorption treatment, an aqueous solution in which 15 g of stannous chloride and 15 cm ³ of 35% hydrochloric acid was diluted to 1 dm ³ with water using a 1 dm ³ volumetric flask was stored at 27 ° C.

For electroless plating treatment, 293 g of ethylenediaminetetraacetic acid tetrasodium (complexing agent), 68 g of sodium hydroxide, 135 cm ³ of formalin are dissolved in 2 dm ³ of water, and an aqueous solution containing a complexing agent and a reducing agent is prepared. Produced. Further, 45 g of silver nitrate, 68 cm ³ of 25% ammonia water, and 225 cm ³ of water were mixed to prepare an aqueous solution containing silver nitrate.

  As a roughening treatment of the surface of the spherical resin particles, a spherical resin particle made of acrylic resin (PMMA cross-linked beads) having a particle diameter of 10 μm is applied to an ozone generator (model ozone super ace, manufactured by Nippon Ozone Generator Co., Ltd.) with a gas concentration of 2 vol%. And ozone treatment was performed by blowing ozone gas for 30 minutes. After cooling, 35 g of the spherical resin particles after the roughening treatment were added to the aqueous solution for tin adsorption treatment and stirred at 30 ° C. for 1 hour. Thereafter, the spherical resin particles were separated by filtration and washed with water. Next, the spherical resin particles subjected to tin adsorption treatment are immersed in the aqueous solution containing the complexing agent and the reducing agent, and the aqueous solution containing silver nitrate is dropped while stirring the aqueous solution, and the spherical resin particles are coated with silver to form silver. Coated spherical resin particles were obtained. The coating amount of silver was 45 parts by mass with respect to 100 parts by mass of the silver-coated spherical resin particles.

<Example 4>
For tin adsorption treatment, an aqueous solution in which 15 g of stannous chloride and 15 cm ³ of 35% hydrochloric acid was diluted to 1 dm ³ with water using a 1 dm ³ volumetric flask was stored at 27 ° C.

For electroless plating treatment, 10.7 g of ethylenediaminetetraacetic acid tetrasodium (complexing agent), 2.5 g of sodium hydroxide, 5 cm ³ of formalin are dissolved in 2 dm ³ of water, and a complexing agent and a reducing agent. An aqueous solution containing was prepared. Further, 1.7 g of silver nitrate, 2 cm ³ of 25% ammonia water, and 10 cm ³ of water were mixed to prepare an aqueous solution containing silver nitrate.

As a roughening treatment of the surface of the spherical resin particles, spherical resin particles made of acrylic resin (crosslinked PMMA beads) having a particle diameter of 35 μm are loaded into a reaction chamber of a plasma generator (glass bell jar type), and the degree of vacuum in the reaction chamber is 20 Pa did. Next, oxygen gas was fed into the reaction chamber at a fixed amount of 15 cm ³ per minute, and 10 W of power was applied to generate plasma for 30 minutes. After cooling, 50 g of spherical resin particles after the roughening treatment were added to the aqueous solution for tin adsorption treatment and stirred at 27 ° C. for 1 hour. Thereafter, the spherical resin particles were separated by filtration and washed with water. Next, the spherical resin particles subjected to tin adsorption treatment are immersed in the aqueous solution containing the complexing agent and the reducing agent, and the aqueous solution containing silver nitrate is dropped while stirring the aqueous solution, and the spherical resin particles are coated with silver to form silver. Coated spherical resin particles were obtained. The silver coating amount was 2 parts by mass with respect to 100 parts by mass of the silver-coated spherical resin particles.

<Example 5>
For tin adsorption treatment, an aqueous solution in which 15 g of stannous chloride and 15 cm ³ of 35% hydrochloric acid was diluted to 1 dm ³ with water using a 1 dm ³ volumetric flask was stored at 27 ° C.

For electroless plating treatment, an aqueous solution containing 312 g of ethylenediaminetetraacetic acid tetrasodium (complexing agent), 72 g of sodium hydroxide, 144 cm ³ of formalin in 2 dm ³ of water and containing a complexing agent and a reducing agent is prepared. Produced. In addition, 47 g of silver nitrate, 60 cm ³ of 25% aqueous ammonia, and 240 cm ³ of water were mixed to prepare an aqueous solution containing silver nitrate.

  As a roughening treatment of the surface of the spherical resin particles, spherical resin particles made of acrylic resin (crosslinked PMMA resin) having a particle diameter of 5 μm are loaded into a hot air dryer (model DX400, manufactured by Yamato Chemical Co., Ltd.) in an air atmosphere at 80 ° C. Hold for 2 hours. After cooling, 20 g of the spherical resin particles after the roughening treatment were added to the aqueous solution for tin adsorption treatment and stirred at 30 ° C. for 1 hour. Thereafter, the spherical resin particles were separated by filtration and washed with water. Next, the spherical resin particles subjected to tin adsorption treatment are immersed in the aqueous solution containing the complexing agent and the reducing agent, and the aqueous solution containing silver nitrate is dropped while stirring the aqueous solution, and the spherical resin particles are coated with silver to form silver. Coated spherical resin particles were obtained. The coating amount of silver was 60 parts by mass with respect to 100 parts by mass of the silver-coated spherical resin particles.

<Example 6>
For tin adsorption treatment, an aqueous solution in which 20 g of stannous chloride and 20 cm ³ of 35% hydrochloric acid was diluted to 1 dm ³ with water using a 1 dm ³ volumetric flask was stored at 25 ° C.

For electroless plating treatment, 416 g of ethylenediaminetetraacetic acid tetrasodium (complexing agent), 96 g of sodium hydroxide, 192 cm ³ of formalin are dissolved in 2 dm ³ of water, and an aqueous solution containing the complexing agent and reducing agent is prepared. Produced. Further, 63 g of silver nitrate, 80 cm ³ of 25% ammonia water, and 320 cm ³ of water were mixed to prepare an aqueous solution containing silver nitrate.

As a roughening treatment of the surface of the spherical resin particles, spherical resin particles made of acrylic resin (crosslinked PMMA resin) having a particle diameter of 1 μm are loaded into a reaction chamber of a plasma generator (glass bell jar type), and the degree of vacuum in the reaction chamber is 10 Pa. did. Next, oxygen gas was fed into the reaction chamber at a constant rate of 15 cm ³ per minute, and 20 W of power was applied to generate plasma for 30 minutes. After cooling, 10 g of spherical resin particles after the roughening treatment were added to the aqueous solution for tin adsorption treatment and stirred at 40 ° C. for 2 hours. Thereafter, the spherical resin particles were separated by filtration and washed with water. Next, the spherical resin particles subjected to tin adsorption treatment are immersed in the aqueous solution containing the complexing agent and the reducing agent, and the aqueous solution containing silver nitrate is dropped while stirring the aqueous solution, and the spherical resin particles are coated with silver to form silver. Coated spherical resin particles were obtained. The coating amount of silver was 80 parts by mass with respect to 100 parts by mass of the silver-coated spherical resin particles.

<Example 7>
For tin adsorption treatment, an aqueous solution in which 15 g of stannous chloride and 15 cm ³ of 35% hydrochloric acid was diluted to 1 dm ³ with water using a 1 dm ³ volumetric flask was stored at 27 ° C.

For electroless plating treatment, 416 g of ethylenediaminetetraacetic acid tetrasodium (complexing agent), 108 g of sodium hydroxide, and 216 cm ³ of formalin are dissolved in 2 dm ³ of water, and an aqueous solution containing the complexing agent and the reducing agent is prepared. Produced. Further, silver nitrate 71 g, 25% aqueous ammonia 902Cm ^3, mixing water 360 cm ³ was prepared an aqueous solution containing silver nitrate.

  As a roughening treatment for the surface of the spherical resin particles, a spherical resin particle made of styrene resin (spherical processed polystyrene resin) having a particle diameter of 10 μm is applied to an ozone generator (model ozone super ace, manufactured by Nippon Ozone Generator Co., Ltd.) with a gas concentration of 2 vol. The ozone treatment was performed by blowing ozone gas at 30% for 30 minutes. After cooling, 55 g of the spherical resin particles after the roughening treatment were added to the aqueous solution for tin adsorption treatment and stirred at 35 ° C. for 1 hour. Thereafter, the spherical resin particles were separated by filtration and washed with water. Next, the spherical resin particles subjected to tin adsorption treatment are immersed in the aqueous solution containing the complexing agent and the reducing agent, and the aqueous solution containing silver nitrate is dropped while stirring the aqueous solution, and the spherical resin particles are coated with silver to form silver. Coated spherical resin particles were obtained. The coating amount of silver was 45 parts by mass with respect to 100 parts by mass of the silver-coated spherical resin particles.

<Example 8>
For tin adsorption treatment, an aqueous solution in which 20 g of stannous chloride and 20 cm ³ of 35% hydrochloric acid were diluted to 1 dm ³ with water using a 1 dm ³ volumetric flask was stored at 45 ° C.

For electroless plating treatment, an aqueous solution containing 325 g of ethylenediaminetetraacetic acid tetrasodium (complexing agent), 75 g of sodium hydroxide, 150 cm ³ of formalin in 2 dm ³ of water and containing a complexing agent and a reducing agent is prepared. Produced. Further, 50 g of silver nitrate, 75 cm ³ of 25% aqueous ammonia, and 250 cm ³ of water were mixed to prepare an aqueous solution containing silver nitrate.

As a roughening treatment of the surface of the spherical resin particles, spherical resin particles made of phenol resin (spherical phenol resin) having a particle diameter of 10 μm are loaded into a reaction chamber of a plasma generator (model YHS-G type, manufactured by Sakai Semiconductor Co., Ltd.). The degree of vacuum in the reaction chamber was 20 Pa. Next, oxygen gas was fed into the reaction chamber at a constant rate of 15 cm ³ per minute, and 20 W of power was applied to generate plasma for 30 minutes. After cooling, 32 g of the spherical resin particles after the roughening treatment were added to the aqueous solution for tin adsorption treatment and stirred at 27 ° C. for 1 hour. Thereafter, the spherical resin particles were separated by filtration and washed with water. Next, the spherical resin particles subjected to tin adsorption treatment are immersed in the aqueous solution containing the complexing agent and the reducing agent, and the aqueous solution containing silver nitrate is dropped while stirring the aqueous solution, and the spherical resin particles are coated with silver to form silver. Coated spherical resin particles were obtained. The coating amount of silver was 50 parts by mass with respect to 100 parts by mass of the silver-coated spherical resin particles.

<Example 9>
For tin adsorption treatment, an aqueous solution in which 15 g of stannous chloride and 15 cm ³ of 35% hydrochloric acid was diluted to 1 dm ³ with water using a 1 dm ³ volumetric flask was stored at 27 ° C.

As for the electroless plating process, the water 2 dm ^3, ethylenediaminetetraacetic acid tetrasodium 728 g (complexing agent), sodium hydroxide 168 g, was dissolved formalin 336Cm ^3, an aqueous solution containing a complexing agent and a reducing agent Produced. Further, 110 g of silver nitrate, 1402 cm ³ of 25% aqueous ammonia, and 560 cm ³ of water were mixed to prepare an aqueous solution containing silver nitrate.

  As a roughening treatment on the surface of the spherical resin particles, spherical resin particles made of phenol resin (spherical phenol resin) having a particle diameter of 3 μm are loaded into a hot air dryer (model DX400, manufactured by Yamato Chemical Co., Ltd.) in an atmospheric atmosphere of 200 ° C. Hold for 2 hours. After cooling, 30 g of the spherical resin particles after the roughening treatment were added to the aqueous solution for tin adsorption treatment and stirred at 35 ° C. for 1 hour. Thereafter, the spherical resin particles were separated by filtration and washed with water. Next, the spherical resin particles subjected to tin adsorption treatment are immersed in the aqueous solution containing the complexing agent and the reducing agent, and the aqueous solution containing silver nitrate is dropped while stirring the aqueous solution, and the spherical resin particles are coated with silver to form silver. Coated spherical resin particles were obtained. The coating amount of silver was 70 parts by mass with respect to 100 parts by mass of the silver-coated spherical resin particles.

<Example 10>
For tin adsorption treatment, an aqueous solution in which 15 g of stannous chloride and 15 cm ³ of 35% hydrochloric acid was diluted to 1 dm ³ with water using a 1 dm ³ volumetric flask was stored at 27 ° C.

For electroless plating treatment, an aqueous solution containing 178 g of ethylenediaminetetraacetic acid tetrasodium (complexing agent), 41 g of sodium hydroxide and 82 cm ³ of formalin in 2 dm ³ of water and containing a complexing agent and a reducing agent is prepared. Produced. Further, 27 g of silver nitrate, 41 cm ³ of 25% aqueous ammonia, and 137 cm ³ of water were mixed to prepare an aqueous solution containing silver nitrate.

  As a roughening treatment of the surface of the spherical resin particles, spherical resin particles made of acrylic resin (crosslinked PMMA resin) having a particle diameter of 20 μm are loaded into a hot air dryer (model DX400, manufactured by Yamato Chemical Co., Ltd.) in an air atmosphere at 80 ° C. Hold for 2 hours. After cooling, 40 g of spherical resin particles after the roughening treatment were added to the aqueous solution for tin adsorption treatment and stirred at 30 ° C. for 1 hour. Thereafter, the spherical resin particles were separated by filtration and washed with water. Next, the spherical resin particles subjected to tin adsorption treatment are immersed in the aqueous solution containing the complexing agent and the reducing agent, and the aqueous solution containing silver nitrate is dropped while stirring the aqueous solution, and the spherical resin particles are coated with silver to form silver. Coated spherical resin particles were obtained. The silver coating amount was 28 parts by mass with respect to 100 parts by mass of the silver-coated spherical resin particles.

<Comparative Example 1>
For tin adsorption treatment, an aqueous solution in which 15 g of stannous chloride and 15 cm ³ of 35% hydrochloric acid was diluted to 1 dm ³ with water using a 1 dm ³ volumetric flask was stored at 27 ° C.

For electroless plating treatment, 288 g of ethylenediaminetetraacetic acid tetrasodium (complexing agent), 53 g of sodium hydroxide and 105 cm ³ of formalin are dissolved in 2 dm ³ of water, and an aqueous solution containing a complexing agent and a reducing agent is prepared. Produced. Further, 35 g of silver nitrate, 53 cm ³ of 25% aqueous ammonia, and 175 cm ³ of water were mixed to prepare an aqueous solution containing silver nitrate.

  Spherical resin particles made of acrylic resin (PMMA cross-linked beads) having a particle diameter of 20 μm were added to the above aqueous solution for tin adsorption treatment, and 41 g of spherical resin particles were added at 30 ° C. without roughening the surface of the spherical resin particles. Stir for hours. Thereafter, the spherical resin particles were separated by filtration and washed with water. Next, the spherical resin particles subjected to tin adsorption treatment are immersed in the aqueous solution containing the complexing agent and the reducing agent, and the aqueous solution containing silver nitrate is dropped while stirring the aqueous solution, and the spherical resin particles are coated with silver to form silver. Coated spherical resin particles were obtained. The silver coating amount was 35 parts by mass with respect to 100 parts by mass of the silver-coated spherical resin particles.

<Comparative Example 2>
For tin adsorption treatment, an aqueous solution in which 15 g of stannous chloride and 15 cm ³ of 35% hydrochloric acid was diluted to 1 dm ³ with water using a 1 dm ³ volumetric flask was stored at 27 ° C.

For electroless plating treatment, 288 g of ethylenediaminetetraacetic acid tetrasodium (complexing agent), 53 g of sodium hydroxide and 105 cm ³ of formalin are dissolved in 2 dm ³ of water, and an aqueous solution containing a complexing agent and a reducing agent is prepared. Produced. Further, 35 g of silver nitrate, 53 cm ³ of 25% aqueous ammonia, and 175 cm ³ of water were mixed to prepare an aqueous solution containing silver nitrate.

  Spherical resin particles made of acrylic resin (PMMA cross-linked beads) having a particle diameter of 15 μm were added to the aqueous solution for tin adsorption treatment, and 41 g of spherical resin particles were added and stirred for 1 hour without performing the roughening treatment on the surface of the spherical resin particles . Thereafter, the spherical resin particles were separated by filtration and washed with water. Next, the spherical resin particles subjected to tin adsorption treatment are immersed in the aqueous solution containing the complexing agent and the reducing agent, and the aqueous solution containing silver nitrate is dropped while stirring the aqueous solution, and the spherical resin particles are coated with silver to form silver. Coated spherical resin particles were obtained. The coating amount of silver was 45 parts by mass with respect to 100 parts by mass of the silver-coated spherical resin particles.

<Comparative Example 3>
For tin adsorption treatment, an aqueous solution in which 15 g of stannous chloride and 15 cm ³ of 35% hydrochloric acid was diluted to 1 dm ³ with water using a 1 dm ³ volumetric flask was stored at 27 ° C.

For electroless plating treatment, 293 g of ethylenediaminetetraacetic acid tetrasodium (complexing agent), 68 g of sodium hydroxide, 135 cm ³ of formalin are dissolved in 2 dm ³ of water, and an aqueous solution containing a complexing agent and a reducing agent is prepared. Produced. Further, 45 g of silver nitrate, 68 cm ³ of 25% ammonia water, and 225 cm ³ of water were mixed to prepare an aqueous solution containing silver nitrate.

  Spherical resin particles made of acrylic resin (PMMA cross-linked beads) having a particle diameter of 10 μm were added to the above aqueous solution for tin adsorption treatment and 35 g of spherical resin particles were added at 30 ° C. without roughening the surface of the spherical resin particles. Stir for hours. Thereafter, the spherical resin particles were separated by filtration and washed with water. Next, the spherical resin particles subjected to tin adsorption treatment are immersed in the aqueous solution containing the complexing agent and the reducing agent, and the aqueous solution containing silver nitrate is dropped while stirring the aqueous solution, and the spherical resin particles are coated with silver to form silver. Coated spherical resin particles were obtained. The coating amount of silver was 45 parts by mass with respect to 100 parts by mass of the silver-coated spherical resin particles.

<Comparison test and results, evaluation>
[Measurement of particle diameter of coated silver]
Photographs of cross sections of the silver-coated spherical resin particles of Examples 1 to 10 and Comparative Examples 1 to 3 were taken with a transmission electron microscope (model JEM-2-1-F, manufactured by JEOL Ltd.), The diameters of silver particles on the resin side and outside of the spherical resin particles of the silver coating layer formed on the surface were visually observed and measured. FIG. 2 shows a photograph of a cross section of the silver-coated spherical resin particles of Example 1 and FIG. The lower left of FIG. 2 is resin (spherical resin particles), and the upper right is a silver coating layer. 2A and 2B, in Example 1, it was observed that silver particles of 10 to 50 nm entered the entire roughened surface of the resin. Further, from FIG. 2 (a), 10-50 nm silver particles from the resin side to around 150 nm, 50-100 nm silver particles around 150-300 nm, and 100-400 nm silver particles above 100 nm, respectively. Observed, silver particles with a maximum of 1000 nm were observed outside, as shown in FIG. 2 (a). 3A and 3B, in Comparative Example 1, it was observed that silver particles of about 10 nm entered the surface of the resin a little. Further, from FIG. 2 (b), silver particles of about 50 nm are scattered on the surface of the resin, and silver particles of about 400 nm are observed above them, and the maximum is 1000 nm outside, as shown in FIG. 2 (b). Of silver particles were observed. Table 1 shows the measurement results (average value of 20 particles) of the average particle diameter of the resin side and outer silver of Examples 1 to 10 and Comparative Examples 1 to 3. In Examples 1 to 10, the average particle size of silver was 10 to 50 nm on the resin side and 100 to 1000 nm on the outside. In Comparative Examples 1 to 3, the resin side was 200 to 300 nm and the outside was 800 to 1000 nm.

[Measurement of powder volume resistance]
2.5 g of silver-coated spherical resin particles were placed in a 25 mm diameter mold, and the powder volume resistivity at the time of pressurization was measured using a resistivity meter (model MCP-T610, manufactured by Mitsubishi Chemical Corporation). In Example 3, it was 3.5 × 10 ⁻⁴ Ω · cm, and in Comparative Example 3, it was 7.5 × 10 ⁻³ Ω · cm.

[Measurement of adhesion]
The produced silver-coated spherical resin particles were put in a container together with an epoxy resin and an amine-based curing agent, and mixed for 30 minutes by a planetary mixer (model name AR100, manufactured by Shinky Corporation). Thereafter, kneading was performed with three rolls. The kneaded paste was observed with a scanning electron microscope (model SU-1500, manufactured by Hitachi High-Technologies Corporation), and it was visually confirmed whether or not the silver plating film was in close contact with the silver-coated spherical resin particles. The case where the silver plating film covered 90% or more of the surface of the silver-coated spherical resin particles was determined as “good”, and the case where it was coated less than 90% was determined as “bad”. In Examples 1 to 10, all the coatings were 90% or more, which was good. On the other hand, in Comparative Examples 1 to 3, the coverage was 80% or less, which was poor. The paste was formed on a PET (Polyethylene Terephthalate) film using an applicator and dried at 80 ° C. for 1 hour to obtain a film having a thickness of 100 μm. The obtained volume resistivity was 5.0 × 10 ⁻⁴ Ω · cm in the films made of the pastes of Examples 1 to 10, whereas 1.8 × in the film made of the pastes of Comparative Examples 1 to 3. 10 ⁻² Ω · cm. In these results of volume resistivity and Examples 1 to 10, since the plating film was not peeled off, it was found that the conductivity was improved as compared with Comparative Examples 1 to 3.

  The silver-coated spherical resin particles of the present invention are conductive particles of a conductive adhesive, more specifically, conductive particles of an isotropic adhesive in the form of an ink, paste or film, or anisotropic in the form of a paste or film. It can utilize for the electroconductive particle of a conductive adhesive.

100 Silver-coated spherical resin particles 101 Spherical resin particles

Claims (8)

Acrylic, phenolic, or styrene-based spherical resin particles, and a silver coating layer composed of an aggregate of silver particles formed on the surface of the spherical resin particles,
In the silver-coated spherical resin particles in which the amount of silver contained in the silver coating layer is 2 to 80 parts by mass with respect to 100 parts by mass of the silver-coated spherical resin particles,
The spherical resin particles have a roughened surface,
Silver coated spherical resin particles, wherein silver particles constituting the silver coated layer in contact with the surface of the spherical resin particles in the silver coated layer enter the roughened surface of the spherical resin particles. The average particle diameter of the silver particles entering the surface of the spherical resin particles is in the range of 10 to 50 nm,
2. The silver-coated spherical resin particles according to claim 1, wherein an average particle diameter of silver particles not entering the surface of the spherical resin particles is in a range of 100 to 1000 nm. An addition step of adding acrylic, phenolic or styrene spherical resin particles to an aqueous solution of tin compound kept at 25 to 45 ° C., and electroless plating using a reducing agent for the aqueous solution of tin compound In the method for producing silver-coated spherical resin particles, including the step of performing silver electroless plating after the tin electroless plating,
A method for producing silver-coated spherical resin particles, comprising a roughening treatment step of roughening the particle surface of the spherical resin particles before the adding step.   The method for producing silver-coated spherical resin particles according to claim 3, wherein the roughening treatment is plasma treatment, ozone treatment or heat treatment at a temperature of 80 to 200 ° C for the spherical resin particles.   A method for producing an anisotropic conductive paste by mixing silver-coated spherical resin particles according to claim 1 or 2 or silver-coated spherical resin particles produced by the method according to claim 3 or 4 and a binder.   A method for producing an anisotropic conductive film adhesive by mixing silver-coated spherical resin particles according to claim 1 or 2 or silver-coated spherical resin particles produced by the method according to claim 3 or 4 and a binder. .   A method for producing an isotropic conductive paste by mixing silver-coated spherical resin particles according to claim 1 or 2 or silver-coated spherical resin particles produced by the method according to claim 3 or 4 and a binder. A method for producing an isotropic conductive film adhesive by mixing silver-coated spherical resin particles according to claim 1 or 2 or silver-coated spherical resin particles produced by the method according to claim 3 or 4 and a binder. .