JP3354382B2 - Method for producing conductive fine particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing conductive fine particles, and more particularly, to a method for producing conductive fine particles having a plating layer having a very uniform thickness without causing aggregation of the fine particles in a plating solution. About.

[0002]

2. Description of the Related Art As a conductive material such as a conductive paste, a conductive adhesive or an anisotropic conductive film, a conductive composition comprising conductive fine particles and a resin is used. As the conductive fine particles, generally, metal powder, carbon powder, or fine particles having a surface provided with a metal plating layer are used.

A method for producing conductive fine particles having a metal plating layer on the surface is disclosed in, for example, JP-A-52-147.
797, JP-A-61-277104, JP-A-61-277105, and JP-A-62-18574.
9, JP-A-63-190204, JP-A-Hei 1
Japanese Patent Application Laid-Open Nos. 225776/1995, 247501/1991 and 147513/1993.

[0004] Among the above-mentioned conventional techniques, a barrel plating apparatus is generally used when plating fine particles having a particle size of 5000 µm or less. In this barrel plating apparatus, an object to be plated is placed in a rotatable polygonal cylindrical barrel immersed in a plating solution, and a cathode disposed in the barrel is brought into contact with the object to be plated while rotating the barrel. The plating is performed.

However, when plating of fine particles having a particle size of 5000 μm or less is performed by a method using this barrel plating apparatus,
In the plating solution, when the fine particles are aggregated and plated and cannot be obtained as a single particle, or even when the fine particles do not aggregate, all the fine particles are not uniformly plated and the thickness of the plating layer often becomes uneven. Was.

In order to solve such a problem, a method of plating the target fine particles in a state where the pseudo particles are put in the barrel together with the target fine particles to be plated has been performed. There is a problem that the number of steps increases because it is necessary to separate the target particles from the target particles.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to prevent fine particles from agglomerating in a plating solution and to reduce the number of steps. An object of the present invention is to provide a method for obtaining conductive fine particles having a plating layer having a simple and extremely uniform thickness.

[0008]

The present inventors have invented a method of producing conductive fine particles using a completely new plating apparatus in order to solve the above-mentioned problems of the conventional fine particle plating method.

That is, in the method for producing conductive fine particles according to the first aspect of the present invention, a rotatable plating apparatus main body having a filter portion formed on at least a part of an outer peripheral portion and having a cathode on the outer peripheral portion; Using a plating apparatus having an anode provided so as not to come into contact with the cathode, while rotating the main body about its rotation axis, the main body is put into the main body while replenishing a plating solution into the main body. and a method for producing conductive fine particles for forming a plating layer on the surface of the fine particles, the
The coefficient of variation of the particle size of the fine particles is 20% or less, the particle size of the conductive fine particles is 0.5 to 5000 μm, and
The coefficient of variation of the particle size of the conductive fine particles is 20% or less .

In a second aspect of the present invention, there is provided a method for producing conductive fine particles, comprising: a disc-shaped bottom plate fixed to an upper end portion of a vertical drive shaft; A contact ring for conducting electricity is arranged on the upper surface of the porous body, and the porous body and the contact ring are sandwiched between the bottom plate and the outer peripheral portion of the truncated cone-shaped hollow cover having an opening at the upper center. A supply pipe for supplying a processing liquid to the processing chamber from the opening, a container for receiving the processing liquid scattered from the porous window, and a discharge pipe for discharging the processing liquid accumulated in the container And, using a plating apparatus having an electrode that is inserted from the opening and comes into contact with the plating solution, the pretreated fine particles are put into the processing chamber, and the conductive fine particles that form a plating layer on the surface of the fine particles are used. a manufacturing method, fine
Variation coefficient of the particle size of the particles is 20% or less, the particle diameter of the conductive fine particles is 0.5～5000Myuemu, and the guide
It is characterized in that the variation coefficient of the particle size of the conductive fine particles is 20% or less .

In a preferred embodiment, the plating layer is made of gold, silver, copper, platinum, zinc, iron, lead, tin, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, cadmium. And at least one selected from the group consisting of silicon
It consists of a kind of metal. The plating layer is not limited to these.

The fine particles used in the present invention may be organic resin fine particles or inorganic fine particles.

Among the conductive fine particles according to the present invention, the plating layer on the surface of the organic resin fine particles or the inorganic fine particles formed of a plurality of kinds of dissimilar metals, which has attracted particular attention in recent years, has been developed under heating conditions. The plating layer on the surface of the fine particles formed from different kinds of metals fuses to form a low melting point alloy.

A typical example is that the plating layer on the surface of the organic resin fine particles or the inorganic fine particles results in the formation of solder. This is used for fine pitch electrode bonding applications in the electronics field, and specifically CO 2
G (chip on glass) and LCD (liquid crystal display element)
It is very suitably used for so-called vertical conduction between upper and lower electrodes.

[0015] The fine particles having a surface plated with solder or having a surface that generates solder as a result are useful for the above-mentioned applications, but there have recently been signs that the use of solder is regulated. Originated from the problem of water pollution caused by lead in Europe and the United States, it has spread to the electronics field, which has a relatively low usage, and there is a possibility that regulations will be enforced in the near future. Therefore, in Japan, the development of lead-free solder, which replaces the conventional tin / lead solder, must be rushed.

The requirements for the materials for lead-free soldering are to satisfy the following points.

There are few environmental problems. Supply is stable. It is a good conductor of electricity and heat. There is no increase in cost. Melting point does not increase. Sufficient mechanical strength is obtained. When designing a lead-free solder alloy composition, Sn (tin), whose production volume is relatively stable at present, is the main component, and in order to adjust its melting point and strength, the second,
It would be realistic to add a third element. When roughly classified, Sn-Ag system, Sn-Zn system, Sn-
In system, Sn-Bi system, Sn-Au system, Sn-S
b-based, Sn-Ge-based, Sn-Cd-based, Sn-Si
System.

Regarding the above Sn-Bi system,
-63110, Japanese Patent Publication No. 7-65206, and Japanese Patent Publication No. 7-65207.

The organic resin fine particles may be fine particles composed of a linear polymer or fine particles composed of a network polymer, and may be fine particles made of a thermosetting resin.
Fine particles made of an elastic material may be used.

Examples of the linear polymer include nylon, polyethylene, polypropylene, methylpentene polymer, polystyrene, polymethyl methacrylate, polyvinyl chloride, polyvinyl fluoride, polytetrafluoroethylene, polyethylene terephthalate, polybutylene terephthalate, Examples include polysulfone, polycarbonate, polyacrylonitrile, polyacetal, and polyamide.

Examples of the network polymer include divinylbenzene, hexatriene, divinyl ether, divinyl sulfone, diallyl carbinol, alkylene diacrylate, oligo or poly (alkylene glycol) diacrylate, oligo or poly (alkylene glycol) diacrylate. Homopolymers of crosslinking reactive monomers such as methacrylate, alkylene triacrylate, alkylene trimethacrylate, alkylene tetraacrylate, alkylene tetraacrylate, alkylene tetramethacrylate, alkylene bisacrylamide, alkylene bismethacrylamide, or these crosslinking reactive monomers and other And a copolymer obtained by copolymerizing the polymerizable monomer with a polymerizable monomer.

Particularly preferred polymerizable monomers include divinylbenzene, hexatriene, divinyl ether, divinylsulfone, alkylene triacrylate, alkylene tetraacrylate and the like.

Examples of the thermosetting resin include a phenol-formaldehyde resin, a melamine-formaldehyde resin, a benzoguanamine-formaldehyde resin, a urea-formaldehyde resin, and an epoxy resin.

Examples of the elastic body include natural rubber and synthetic rubber.

As the material of the inorganic fine particles, silica,
Known materials such as titanium oxide, iron oxide, cobalt oxide, zinc oxide, nickel oxide, manganese oxide, and aluminum oxide can be used.

The fine particles have a particle size of 0.5 to 5000 μm.
m, particularly preferably 0.5 to 2500 μm, more preferably 1 to 1000 μm. And the coefficient of variation of the particle size is 50% or less, preferably 35% or less;
It is more preferably at most 20%, most preferably at most 10%.

On the surface of such fine particles, a conductive underlayer is usually formed in advance. As the formation of the conductive underlayer, an electroless plating method described below is preferably used, but the present invention is not limited to this, and it is also possible to form the conductive underlayer by other known methods for imparting conductivity. The step of forming the conductive underlayer by the electroless plating method is generally divided into an etching step, an activation step, and an electroless plating step.

(1) The above-mentioned etching step is a step for forming irregularities on the surface of the fine particles to impart adhesion to the fine particle surface of the conductive underlayer.
For example, an aqueous sodium hydroxide solution, concentrated hydrochloric acid, concentrated sulfuric acid or chromic anhydride is used. However, the etching step is not always necessary, and may be omitted in some cases.

(2) The activation step is a step of forming a catalyst layer on the surface of the etched fine particles and activating the catalyst layer. The activation of the catalyst layer promotes the deposition of metal in an electroless plating step described below. Examples of the catalyst used include Pd ²⁺ ,
Sn ^{2+ and the} like. The catalyst such as Pd ²⁺ and Sn ²⁺ is adsorbed on the surface of the fine particles to form a catalyst layer.
The concentrated catalyst or concentrated sulfuric acid is allowed to act on the formed catalyst layer,

[0030]

(Equation 1)

Pd ²⁺ is metallized by the above reaction. The metallized palladium is activated and sensitized by a palladium activator such as a concentrated solution of sodium hydroxide.

(3) The electroless plating step is a step for imparting conductivity to the fine particles by forming a plating layer on the surface of the activated fine particles. For example, in the case of nickel plating, nickel is used. Nickel sulfate is used as an ion supplying substance, and sodium hypophosphite is added as a reducing agent. The palladium adsorbed on the surface of the fine particles in the activation step serves as a catalyst, and the reduction reaction of nickel sulfate proceeds to deposit nickel metal on the surface of the fine particles.

(4) In the electroless plating step, a conductive base layer (conductive plating layer) is formed on the surface of the fine particles on which the catalyst layer is formed.
Is a step of forming

The conductive plating layer formed by the electroless plating step may be a single layer or two or more layers. When it is desired to provide a gold plating layer on a nickel plating layer, Electroless plating may be performed in the same manner as in the case of nickel plating using potassium gold cyanide as a gold ion supply material. When three or more plating layers are to be stacked on the gold plating layer, it is convenient to perform electroplating.

Next, a plating apparatus that can be used in the present invention will be described.

As shown in FIG. 1, the plating apparatus A allows a disc-shaped plastic bottom plate 11 fixed to the upper end of a vertical drive shaft 3 to pass only a processing solution through an outer peripheral upper surface of the bottom plate 11. A porous ring 13 is arranged as a filter part,
An energizing contact ring 12 is arranged on the upper surface of the porous ring 13 as a cathode. And a supply pipe 6 for supplying a processing liquid or the like to the processing chamber 4 through the opening 8 and a plastic container 5 for receiving the processing liquid scattered from the porous window. And a discharge pipe 7 for discharging the processing solution stored in the container 5, and an anode 2a inserted through the opening 8 and in contact with the plating solution.

The porous ring 13 is a filter-like porous body having open cells formed of plastic or ceramic, and has a pore diameter that allows a processing solution such as a plating solution to pass through but does not allow fine particles (and conductive fine particles) to pass. Things are adopted.

The processing solution receives the centrifugal force due to the rotation of the drive shaft 3, passes through the porous ring 13, and scatters around, thereby lowering the level of the processing solution in the processing chamber. The processing liquid is supplied to the processing chamber 4 from the supply pipe 6 for supplying the processing liquid from the opening 8, and the liquid amount is controlled so that the liquid level in the processing chamber 4 is always in contact with the electrode 2a. In the figure, reference numeral 2 denotes a positive electrode, which is connected to the anode 2a. 9 is a plating solution level sensor, and 10 is a contact brush. The power supply for the electrodes is not shown.

Hereinafter, a method for producing conductive fine particles using the plating apparatus A will be described.

The plating solution is supplied from the processing solution supply pipe 6 into the processing chamber 4, and then the processing chamber 4 is opened through the opening 8 of the cover 1.
Then, the fine particles having the conductive underlayer formed thereon are introduced and dispersed. When the particles are to be introduced into the processing chamber 4, the drive shaft 3 is rotated. Since the plating solution flows out of the processing chamber 4 through the porous ring 13 with the rotation of the drive shaft 3, the reduced amount is supplied from the processing solution supply pipe 6. Other plating conditions are not particularly different from those of normal plating.

In order to form a more uniform plating layer,
It is preferable that the rotation direction of the drive shaft 3 is reversed or stopped at regular intervals.

Thus, conductive fine particles having a plating layer formed on the surface are obtained. The particle size of the obtained conductive fine particles is 0.5 to 5000 μm, preferably 1 to 2 μm.
500 μm, more preferably 1 to 1000 μm
m, most preferably from 2 to 500 μm.

The coefficient of variation of the particle size is 50% or less, preferably 35% or less, more preferably 20% or less.
Or less, most preferably 10% or less. Here, the coefficient of variation is the standard deviation expressed as a percentage based on the average value, and is expressed by the following equation.

[0044]

(Equation 2)

When the particle size of the conductive fine particles is less than 0.5 μm or more than 5000 μm, a large number of agglomerates of plated particles are observed, and the coefficient of variation of the particle size is 50%. Even when it exceeds, a large number of agglomerates of plating particles are observed.

The thickness of the plating layer formed on the surface of the conductive fine particles is preferably 0.001 to 5.0 μm,
01 to 1 μm is more preferable. Further, the coefficient of variation of the thickness of the plating layer is preferably 20% or less, more preferably 10% or less.

By putting water in the container 5 in place of the plating solution, the obtained conductive fine particles can be used for washing.

[0048]

While the drive shaft is rotating, the plating solution and the fine particles on which the conductive underlayer is formed are immersed in the plating solution in the processing chamber 4, and the contact ring 12 (cathode) and the anode 2a are formed.
Is applied between both electrodes. The fine particles are pressed against the contact ring 12 by the action of centrifugal force, and a plating layer is formed on the fine particles facing the anode 2a. When the drive shaft 3 stops, the fine particles are attracted by the flow of gravity and the inertia of the plating solution, flow down to the flat surface at the center of the bottom plate, and mix, and then when the drive shaft 3 starts to reverse, the fine particles mix. While being fitted, it is pressed against the contact ring 12 by the action of the centrifugal force in another posture, so that a plating layer is formed on the other fine particles facing the anode 2a. By repeating the rotation and stop of the drive shaft 3 in this manner, plating is uniformly performed on all the fine particles present in the processing chamber 4.

[0049]

【Example】

Example 1 A nickel plating layer was formed as a conductive underlayer on organic resin fine particles obtained by copolymerizing styrene and divinylbenzene, and nickel-plated fine particles having an average particle size of 6.53 μm and a standard deviation of 0.26 μm were formed. Obtained. 50 g of the obtained nickel-plated fine particles were taken, and the surface thereof was subjected to gold plating using a plating apparatus shown in FIG.

The processing chamber 4 has a diameter of 20 cm and a height of 10 cm.
The porous ring 13 is a filter-like porous body having open cells formed of plastic, and the anode 2a is made of stainless steel.

The composition of the plating solution contains 8 g of potassium potassium cyanide, 90 g of potassium cyanide, and 0.1 g of brightener per liter of water.

The temperature of the plating solution was 25 ° C., the current was 10 A,
A current density of 0.004 A / dm ² and a voltage of 4 to 5 V were applied between both electrodes for 8 hours. The rotation speed of the drive shaft 3 is 30
Hz, and the rotation direction was reversed every 10 seconds.

Observation of the gold-plated resin fine particles whose outermost shell was a gold-plated layer by an optical microscope revealed that there was no aggregation and all the particles were present as single particles. As a result of observing 100 gold-plated resin fine particles with an electron microscope, the average particle diameter was 6.93 μm.
m, the thickness of the gold plating layer was calculated to be 0.2 μm. The coefficient of variation of the particle size was 2.5%, which proved that the thickness of the gold plating layer was extremely uniform.

(Comparative Example 1) Gold-plated resin fine particles were obtained in exactly the same manner as in Example 1 except that a conventional barrel plating apparatus was used as the plating apparatus.

When the gold-plated resin fine particles were observed with an optical microscope, many to several tens of agglomerates were observed. Further, as a result of observing 100 of the gold-plated resin particles with an electron microscope, the average particle diameter was calculated to be 6.83 μm, and the thickness of the gold plating layer was calculated to be 0.15 μm. The variation coefficient of the particle size was 12.5%, which proved that the thickness of the gold plating layer was extremely uneven.

Example 2 Instead of the organic resin fine particles,
Except that 50 g of nickel-plated silica fine particles (average particle size: 5.43 μm, standard deviation: 0.16 μm) obtained by nickel plating on the surface of silica fine particles were used, gold-plated resin fine particles were completely the same as in Example 1. I got

Observation of the gold-plated silica particles whose outermost shell was a gold-plated layer by an optical microscope showed that there was no aggregation and all the particles were present as single particles. As a result of observing 100 of the gold-plated silica particles with an electron microscope, the average particle size was 5.77 μm.
m, the thickness of the gold plating layer was calculated to be 0.17 μm. The coefficient of variation of the particle size was 2.8%, which proved that the thickness of the gold plating layer was extremely uniform.

Comparative Example 2 Gold-plated silica fine particles were obtained in exactly the same manner as in Example 2 except that a conventional barrel plating apparatus was used as the plating apparatus.

When the gold-plated silica fine particles were observed with an optical microscope, several to several tens of aggregates were found in large numbers. In addition, as a result of observing 100 gold-plated silica fine particles with an electron microscope, the average particle diameter was calculated to be 5.73 μm, and the thickness of the gold plating layer was calculated to be 0.15 μm. The coefficient of variation of the particle size was 13.6%, which proved that the thickness of the gold plating layer was extremely uneven.

Example 3 Using the same plating apparatus as in Example 1, the conductive fine particles obtained in Example 1 (the average particle size of the outermost shell being a gold plating layer is 6.93 μm, (0.2 μm in thickness) was subjected to solder plating using the plating apparatus shown in FIG.

The composition of the plating solution contained stannous alkanesulfonate 75 g / l, lead alkanesulfonate 3 g / l, free alkanesulfonic acid 270 g / l, and brightener 30 ml / l in 1 liter of water.

The temperature of the plating solution was 25 ° C., the current was 10 A,
A current density of 3 A / dm ² and a voltage of 4 to 5 V were applied between both electrodes for 5 hours.

The rotation speed of the drive shaft was 25 Hz, and the rotation direction was reversed every 20 seconds.

Observation of the solder-plated fine particles, the outermost shell of which was a solder-plated layer, by an optical microscope showed that there was no aggregation and all the particles were present as single particles. Further, as a result of observing 100 of the solder plated fine particles with an electron microscope, the average particle diameter was 8.13 μm, and the thickness of the solder plated layer was 0.6 μm. The coefficient of variation of the particle size was 2.9%, which proved that the thickness of the solder plating layer was extremely uniform.

Comparative Example 3 Solder fine particles were obtained in exactly the same manner as in Example 3 except that a conventional barrel plating apparatus was used as the plating apparatus.

When these solder plated fine particles were observed with an optical microscope, many to several tens of agglomerates were observed. Further, as a result of observing 100 of the solder plated fine particles with an electron microscope, the average particle diameter was 8.03 μm, and the thickness of the solder plated layer was 0.55 μm. The coefficient of variation of the particle size is 1
At 4.3%, it was proved that the thickness of the solder plating layer was extremely uneven.

Example 4 Styrene and divinylbenzene were copolymerized to give an average particle size of 6.53 μm and a coefficient of variation of 1.
7% of organic resin fine particles were obtained. Nickel plating and gold plating were performed in the same manner as in Example 1 except that the organic resin fine particles were used, to obtain gold-plated resin fine particles.

The obtained gold-plated resin fine particles 100
The individual particles were observed with an electron microscope, and as a result, the average particle size was 6.93 μm.
m, the thickness of the gold plating layer was calculated to be 0.20 μm. The coefficient of variation of the particle size was 19%.

Further, Table 1 shows the degree of aggregation of the gold-plated resin particles of the particles. As shown in Table 2, the degree of particle agglomeration was shown in grades classified according to the number of agglomerates composed of five or more particles present in 1,000 gold-plated resin fine particles.

(Examples 7 , 10 ; Comparative Examples 4 to 6, Comparative Examples 9 and 10 , and Comparative Examples 19 to 24 ) The average particle diameters and fluctuations shown in Table 1 obtained by copolymerizing styrene and divinylbenzene. Nickel plating and gold plating were performed in the same manner as in Example 1 except that organic resin fine particles having a coefficient were used to obtain gold-plated resin fine particles having a particle diameter and a variation coefficient shown in Table 1. Table 1 shows the degree of aggregation of the gold-plated resin particles.

(Examples 13 and 16 , Comparative Examples 7, 8 and 11 , and Comparative Examples 25-27 ) Except that instead of the organic resin fine particles, silica fine particles having different particle diameters and coefficients of variation shown in Table 1 were used. Then, nickel plating and gold plating were performed in the same manner as in Example 1.
The gold-plated resin fine particles having the particle diameter and the coefficient of variation shown in Table 1 were obtained. Table 1 shows the degree of aggregation of the gold-plated resin particles.

Example 19 The nickel-plated organic resin fine particles used in Example 1 were used as substrates.

A plating solution having the following composition was prepared, and tin-bismuth (S) was added under the following conditions while replenishing stannous oxide by the following method.
n-Bi) Plating was performed.

Liquid composition Bismuth methanesulfonate 50 g / l (Bi = 21 g)
/ L) stannous methanesulfonate 23g / l (Sn = 9g /
l) Methanesulfonic acid 200 g / l Alkyl nonylphenyl ether 5 g / l Plating conditions Cathode current density 0.3 A / dm ² Bath temperature 20 ° C. Anode Bi (99.99% or more) Plating time 240 minutes Tin replenishment stannous oxide Was dissolved in a separate tank and replenished. Replenishment frequency is 40
Once per minute, Sn was replenished at 0.3 g / liter / time.

By employing the above plating method, the Bi amount and the Sn amount in the plating solution hardly fluctuate between the initial stage of plating and 240 minutes after plating, and the appearance and precipitate of the obtained precipitate (Bi-Sn alloy) The Bi content therein was 30-35%, almost the same between the initial stage of plating and after 240 minutes, and was stable.

In the above plating method, the Bi anode was used, so that Bi substitutional precipitation did not occur. However, when the Bi—Sn (7/3) alloy was used as the anode and tin was not supplied. During the suspension of plating, Bi in the plating solution was replaced and precipitated on the Bi—Sn alloy anode, and Bi in the solution was accordingly reduced.
Since the amount decreased and the Sn amount increased, the subsequent plating resulted in a Bi—Sn alloy plating film having a low Bi amount and a large Sn amount.

Comparative Example 12 Tin-bismuth-plated organic resin fine particles were obtained in exactly the same manner as in Example 19 except that a conventional barrel plating apparatus was used as the plating apparatus.

Reference Example 1 The nickel-plated silica fine particles used in Example 2 were used as a substrate.

A plating solution having the following composition was prepared, and tin-bismuth (S) was added under the following conditions while replenishing stannous sulfate by the following method.
n-Bi) Plating was performed.

Liquid composition 73 g / l of bismuth phenol sulfonate (Bi = 2
1 g / l) Stannous phenol sulfonate 35 g / l (Sn = 9)
g / l) Phenolsulfonic acid 350 g / l Alkyl nonyl phenyl ether 5 g / l Plating conditions Cathode current density 2 A / dm ² Bath temperature 20 ° C. Anode Bi (99.99% or more) Plating time 20 minutes Tin replenishment stannous sulfate Was added to, dissolved in, and supplied to the plating solution in the displacement plating tank. The replenishment frequency was once every 10 minutes, and the replenishment was 0.5 g / liter / time as Sn.

By employing the above plating method, there is almost no change in the amount of Bi and Sn in the plating solution between the initial plating and 20 minutes after the plating, and the appearance and precipitate of the obtained precipitate (Bi-Sn alloy) The Bi content therein was 30-35%, almost the same at the initial stage of plating and after 20 minutes, and was stable.

In the above plating method, when Bi—Sn (7/3) alloy was used as the anode and tin was not supplied, Bi in the plating solution was changed to Bi—
Substitution precipitation occurred on the Sn alloy anode, and the Bi amount in the solution decreased and the Sn amount increased by that amount. Therefore, in the subsequent plating, a Bi-Sn alloy plating film having a low Bi amount and a large Sn amount was obtained.

Comparative Example 13 Tin-bismuth-plated silica fine particles were obtained in exactly the same manner as in Reference Example 1 , except that a conventional barrel plating apparatus was used as the plating apparatus.

(Example 21) 50 g of the nickel-plated organic resin fine particles used in Example 1 were used as a base material.

A plating solution having the following composition was prepared, and Sn-Ag plating was performed in the same manner as in Example 1.

Liquid composition Potassium stannate 50 g / l (20 g / l as metal tin) Silver potassium cyanide 10 g / l Potassium hydroxide 50 g / l Sodium acetate 5 g / l Potassium cyanide 50 g / l Potassium carbonate 5 g / l Cathode current density 1 A / dm ( ²⁾ Bath temperature 35 ° C. (Comparative Example 14) Tin-plating was performed in exactly the same manner as in Example 21 except that a conventional barrel plating apparatus was used as the plating apparatus.
Silver-plated organic resin fine particles were obtained.

Reference Example 2 The base material was 50 g of the nickel-plated silica fine particles used in Example 2.

A plating solution having the following composition was prepared, and Sn-Au plating was performed in the same manner as in Example 1.

Liquid composition Potassium stannate 50 g / l (20 g / l as metal tin) Potassium cyanide 50 g / l Potassium hydroxide 15 g / l Sodium acetate 5 g / l Potassium cyanide 50 g / l Potassium carbonate 15 g / l Potassium phosphate 15 g / L Cathode current density 1.5 A / dm ² Bath temperature 65 ° C (Comparative Example 15) Tin-gold-plated silica fine particles were obtained in exactly the same manner as in Reference Example 2 except that a conventional barrel plating apparatus was used as the plating apparatus. Was.

Example 23 The base material was 50 g of the nickel-plated organic resin fine particles used in Example 1.

A plating solution having the following composition was prepared, and Sn-Zn plating was performed in the same manner as in Example 1.

Liquid composition Potassium stannate 50 g / l (20 g / l as metal tin) Zinc cyanide 30 g / l (20 g / l as zinc metal) Potassium cyanide 20 g / l Sodium cyanide 20 g / l Potassium hydroxide 15 g / l Water Sodium oxide 45 g / l Sodium acetate 5 g / l Cathode current density 5 A / dm ² Bath temperature 40 ° C. (Comparative Example 16) Tin-plating was performed in exactly the same manner as in Example 23 except that a conventional barrel plating apparatus was used as the plating apparatus.
The zinc-plated organic resin fine particles were obtained.

(Reference Example 3) 50 g of the nickel-plated silica fine particles used in Example 2 were used as a base material.

A plating solution having the following composition was prepared, and Sn—Sb plating was performed in the same manner as in Example 1.

Liquid composition Stannous methanesulfonate 20 g / l Antimony methanesulfonate 60 g / l Methanesulfonic acid 250 g / l Alkyl nonylphenyl ether 5 g / l Cathode current density 1 A / dm ² Bath temperature 30 ° C. (Comparative Example 17) Except that a conventional barrel plating apparatus was used as the plating apparatus, tin-antimony-plated silica fine particles were obtained in exactly the same manner as in Reference Example 3 .

(Example 25) 50 g of the nickel-plated organic resin fine particles used in Example 1 were used as a base material.

A plating solution having the following composition was prepared, and Sn—Cd plating was performed in the same manner as in Example 1.

Liquid composition Potassium stannate 50 g / l (20 g / l as metal tin) Sodium cadmium cyanide 40 g / l Potassium cyanide 20 g / l Sodium cyanide 20 g / l Potassium hydroxide 15 g / l Sodium hydroxide 45 g / l Sodium acetate 5 g / l Cathode current density 2 A / dm ² Bath temperature 30 ° C. (Comparative Example 18) The same procedure as in Example 94 was carried out except that a conventional barrel plating apparatus was used as the plating apparatus.
Antimony-plated silica fine particles were obtained.

Table 2 shows the results of the above Examples and Comparative Examples .

[0100]

[Table 1]

[0101]

[Table 2]

[0102]

[Table 3]

From the results shown in Tables 1 and 2, when the average particle size of the plated particles is less than 0.5 μm or more than 5000 μm and when the coefficient of variation of the particle size exceeds 50%, the plated particles Was 5 and the number of aggregates of the particles was large.

[0104]

According to the method of the present invention, for example, a particle size of 5
Even if fine particles having a small particle size of 000 μm or less are used, the fine particles are easily aggregated in the plating solution and cannot be obtained as a single particle by being plated as they are, and the thickness of the plating layer is not uniform, and the method is simple. The present invention provides a method for producing conductive fine particles having a plating layer with a very uniform thickness using a simple apparatus.

The conductive fine particles obtained by the production method of the present invention can be used as a spacer for a conductive material such as a conductive paste, a conductive adhesive or an anisotropic conductive film, and have extremely excellent properties. .

[Brief description of the drawings]

FIG. 1 is a schematic view of a plating apparatus used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cover 2 Electrode 2a Anode 3 Rotation axis 5 Container 6 Plating solution supply pipe 7 Plating solution discharge pipe 8 Opening 11 Bottom plate 12 Contact ring 13 Porous ring

Continuation of the front page (72) Inventor Toichi Yamada 2-4-4 Nishitenma, Kita-ku, Osaka-shi, Osaka Within Sekisui Fine Chemical Co., Ltd. (72) Inventor Yutaka Sugiura 1-5-1 Exit, Hirakata-shi, Osaka, Uemura (56) References JP-A-8-239799 (JP, A) JP-A-7-118896 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C25D 7/00 C25D 17/16-17/26

Claims (3)

(57) [Claims] 1. A rotatable plating apparatus main body having a filter portion formed on at least a part of an outer peripheral portion and having a cathode on the outer peripheral portion, and an anode provided in the main body so as not to contact the cathode. using a plating apparatus, while rotating the body about its axis of rotation, the conductive fine particles for forming a plating layer on the surface of the fine particles placed within the body while replenishing the plating solution within the body A production method, wherein the coefficient of variation of the particle size of the fine particles is 20% or less, the particle size of the conductive fine particles is 0.5 to 5000 μm, and
Method for producing a conductive fine particle, wherein the variation coefficient of the particle diameter of the conductive fine particles is 20% or less. 2. A disc-shaped bottom plate fixed to the upper end of a vertical drive shaft, and a porous body through which only the processing liquid passes are disposed on the outer peripheral upper surface of the bottom plate. The processing chamber formed by sandwiching the porous body and the contact ring between the bottom plate and the outer periphery of the truncated cone-shaped hollow cover having an opening at the upper center is formed, and the processing liquid is supplied through the opening. A supply pipe for supplying to the processing chamber, a container for receiving the processing liquid scattered from the porous window, a discharge pipe for discharging the processing liquid accumulated in the container, and an electrode inserted from the opening to contact the plating solution. using a plating apparatus having put the pretreatment of applying the fine particles to the processing chamber, a method for producing conductive fine particles for forming a plating layer on the surface of the fine particles, the variation coefficient of the particle size of the fine particles 20% or less, and the particle size of the conductive fine particles is 0.5 % or less. ５5000 μm, and
Method for producing a conductive fine particle, wherein the variation coefficient of the particle diameter of the conductive fine particles is 20% or less. 3. The group wherein the plating layer comprises gold, silver, copper, platinum, zinc, iron, lead, tin, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, cadmium and silicon. The method for producing conductive fine particles according to claim 1, comprising at least one metal selected from the group consisting of: