JP2002322591A - Method for plating fine particle, electrically conductive fine particle and connected structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for plating fine particles by which the flocculation of plated particles can be suppressed and fine particles free from flaws or peeling on the plating layer in the surface can be obtained. SOLUTION: The method for plating fine particles uses a rotary type plating apparatus which is provided with a cathode 12 on the outer circumferential part, a rotatable dome 1 having a filter part 13 through which a plating solution passes to be exhausted, and an anode 2a set so as not to contact with the cathode in the dome, and which repeats energizing and stirring while allowing the fine particles to contact with the cathode by the centrifugal force due to rotation of the dome. Dummy particles which have a hardness equal to that of the base material particles to be plated and have a particle size of 1.5 to 30 times that of the base material particles to be plated are simultaneously added, and plating is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used to connect electrodes, and reduces the force applied in a circuit.
The present invention relates to a conductive fine particle and a conductive connection structure having improved connection reliability.

[0002]

2. Description of the Related Art Conventionally, ICs and Ls have been used in electronic circuit boards.
In order to connect the SI, a method of soldering each pin on a printed circuit board has been used, but this method has a low production efficiency and is not suitable for high density.

Further, in order to solve the connection reliability, a technique such as a ball grid array (BGA) in which solder is made spherical, that is, a solder ball is used to connect to a substrate, has been developed. According to this technique, an electronic circuit that achieves both high productivity and high connection reliability can be configured by connecting the substrate and the chip and the solder balls mounted on the substrate while melting them at a high temperature.

However, in recent years, the number of substrates has been increased, and distortion and expansion and contraction have occurred due to changes in the external environment of the substrates themselves.
As a result, there has been a problem that disconnection occurs due to the application of the force to the connection between the substrates. In addition, due to the multi-layer structure, the distance between the substrates can hardly be secured, and a spacer or the like must be separately provided to maintain the distance, which is troublesome and costly.

[0005] As means for solving these problems, in order to reduce the force applied to the circuit such as the substrate, it is reinforced by applying a resin or the like to the substrate connection portion. However, there is a problem that it takes much time and costs increase due to an increase in the number of coating steps.

In order to solve the above-mentioned problem, in order to maintain the distance between substrates and to reduce the force applied to a circuit such as a substrate, particles coated with solder using copper as a core (Japanese Patent Laid-Open No. 11-74311). JP-A No. 05-0363) and particles obtained by plating solder with a resin as a core (Japanese Patent Laid-Open No. 05-0363).
No. 06 publication) has been proposed.

[0007] Further, as a method for producing the fine particles having a solder layer, a rotatable dome having a cathode at an outer peripheral portion and having a filter portion through which a plating solution is passed and discharged,
The dome has an anode installed so as not to contact the cathode, and uses a rotary plating apparatus that repeats energization and stirring by bringing fine particles into contact with the cathode by the effect of centrifugal force due to rotation of the dome. There has been proposed a method for plating fine particles (JP-A-9-137289). in this way,
It is known that plating particles are less agglomerated and can be plated uniformly as compared with ordinary barrel plating.

However, even with this rotary plating apparatus, agglomeration occurs when the particle diameter of the plating base material becomes small and the thickness of the plating film becomes large. On the other hand, it is known that aggregation is suppressed when plating is performed while adding a crushing effect by adding hard, large-diameter dummy particles such as stainless steel or zirconia. However, when the dummy particles are used, they violently collide with the base particles at the time of crushing, so that there is a problem that plating peeling or cracking occurs and the surface state is largely deteriorated.

[0009]

SUMMARY OF THE INVENTION In view of the above, the present invention provides a method of plating fine particles for suppressing aggregation of plated particles and obtaining fine particles having no scratches or peeling on a surface plating layer. The purpose is to provide.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve these problems, and has the same hardness as that of the base particles when plating fine particles using the rotary plating apparatus. And plating is performed by simultaneously adding dummy particles having a particle size of 1.5 to 30 times the size of the base particles to be plated. Hereinafter, the present invention will be described in detail.

The conductive fine particles of the present invention are obtained by covering the surface of base particles composed of resin and metal balls with one or more metal layers. The composition of these base particles is not particularly limited, but is preferably resin in consideration of the function of imparting a stress relaxation function during mounting. Examples of the resin include polystyrene, a polystyrene copolymer, a polyacrylate, a polyacrylate polymer, a phenol resin, a polyester resin, and polyvinyl chloride. These may be used alone or in combination of two or more. The shape of the base particles is not particularly limited as long as they are spherical, and may be, for example, hollow. The metal balls include silver, copper, nickel, silicon, gold,
A high melting point metal such as titanium is used.

Although the particle size of these base particles is not particularly limited, considering the usage of mounting materials such as BGA and CSP, those having a particle size of 1 to 1000 μm are useful, and furthermore, aggregation in a rotary plating apparatus is difficult. 1-5 for ease
It is effective for particles of 00 μm.

The conductive fine particles of the present invention are obtained by coating the above-mentioned base particles with one or more layers of metal. Examples of the metal to be coated include gold, silver, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, cadmium, and silicon. These metals may be one kind,
The plating layer may be formed as an alloy composition of two or more types. For example, a configuration in which a nickel layer is plated on polystyrene resin base particles, and copper or tin is further plated thereon.

Although the thickness of the metal layer is not particularly limited,
Considering applications such as conductive bonding and substrate bonding, it is preferable to use 0.
It is preferably from 01 to 500 μm. 0.01 μm
If it is less than 500 μm, it is difficult to obtain a favorable conductivity. If it exceeds 500 μm, the particles may coalesce, or the function of maintaining the distance between substrates or reducing the force applied to a circuit such as a substrate may be reduced.

In the method for plating fine particles of the present invention,
It has a rotatable dome having a filter part for passing and discharging the plating solution, and an anode provided in the dome so as not to contact the cathode, by the effect of centrifugal force due to the rotation of the dome. A rotary plating apparatus is used in which fine particles are brought into contact with a cathode and current is repeatedly applied and stirred.

FIG. 1 shows a schematic view of an example of this rotary plating apparatus. The plating apparatus A has a disc-shaped plastic bottom plate 11 fixed to the upper end of the vertical drive shaft 3, and a porous ring 13 as a filter portion for passing only the processing liquid on the outer peripheral upper surface of the bottom plate 11. An energizing contact ring 12 is arranged on the upper surface of the porous ring 13 as a cathode, and the porous ring 13 and the contact ring 12 are connected to the bottom plate at the outer peripheral portion of the truncated cone-shaped plastic hollow cover 1 having an opening 8 at the upper center. A processing chamber 4 sandwiched between the processing chamber 4 and a supply pipe 6 for supplying a processing liquid or the like to the processing chamber 4 through an opening 8 and a plastic container 5 for receiving the processing liquid scattered from a porous window. A discharge pipe 7 for discharging the processing liquid accumulated in the container 5,
And an anode 2a inserted through the opening 8 and in contact with the plating solution.

While rotating the drive shaft 3, the processing chamber 4
The fine particles having the conductive underlayer formed thereon are immersed in the plating solution, and current is applied between the contact ring 12 (cathode) and the anode 2a. The fine particles are pressed against the contact ring 12 by the action of the centrifugal force to form a plating layer on the fine particles facing the anode 2a. When the drive shaft 3 stops, the fine particles are dragged by the action of gravity and the inertia of the plating solution, flow down to the flat surface at the center of the bottom plate, and mix with each other while being centrifugally acting in another position by the action of the centrifugal force. Therefore, a plating layer is formed on another fine particle 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.

In the present invention, the dummy particles having the same hardness as the base particles to be plated and having a particle diameter of 1.5 to 30 times the base particles to be plated are simultaneously added. I do.

The hardness of the above-mentioned dummy particles is usually in the range of 100 to 600 kgf / mm ² in terms of compression elastic modulus.
Therefore, those having the same hardness are desirable. If the compression modulus is less than 100 kgf / mm ² ,
Since the weight with the plating substrate is too different, the crushing effect of the dummy is insufficient. On the other hand, if it exceeds 600 kgf / mm ² , the surface of the base particles is undesirably peeled or scratched.

That is, it is preferable to use dummy particles having a resin composition without using metals such as stainless steel and iron, and inorganic substances such as zirconia and alumina. The resin composition is not particularly limited, and examples thereof include polystyrene, a polystyrene copolymer, a polyacrylate, a polyacrylate copolymer, a phenol resin, a polyester resin, polyvinyl chloride, and nylon. These may be used alone or in combination of two or more.

The particle size of the dummy particles is preferably about 1.5 to 30 times that of the base particles to be plated. If the particle diameter of the dummy particles is smaller than 1.5 times, it becomes difficult to separate the plated particles from the dummy particles, which is not preferable. 3
If it is larger than 0 times, the base particles to be plated enter into the gap between the dummy particles, and it is difficult to obtain a substantial crushing effect, which is not preferable.

The fine particles plated by the fine particle plating method of the present invention can be used as conductive fine particles used for connecting between electrodes. The conductive fine particles can improve connection reliability by reducing the force applied in the circuit. A conductive connection structure using the conductive fine particles is also one aspect of the present invention.

[0023]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 In a separable flask, 1.3 parts by weight of benzoyl peroxide as a polymerization initiator were uniformly mixed with 20 parts by weight of divinylbenzene, 20 parts by weight of a 3% aqueous solution of polyvinyl alcohol, and dodecyl sulfate. After adding 0.5 parts by weight of sodium and stirring well, 140 parts by weight of ion-exchanged water was added. The solution was stirred at 80 ° C. for 15
A time reaction was performed. After the obtained fine particles are washed with hot water and acetone, the particles are selected with a sieve, and the center particle diameter is 30%.
0 μm particles were obtained. Nickel plating was formed thereon by electroless plating as a conductive underlayer. With the same prescription, nickel-plated dummy particles having a center particle diameter of 800 μm were synthesized.

Next, 40 g of nickel-plated particles and 20 mL of 800 μm dummy particles were charged into a rotary plating apparatus, and copper plating was performed. The plating conditions were as follows: bath temperature 30 ° C., current density 0.5 A / dm ² ,
The rotation direction was reversed every 40 seconds at a peripheral speed of 18 Hz.

The obtained particles were sieved with a sieve having an opening of 700 μm to separate 800 μm dummy particles and plating particles. When the cross section of the plating particles thus obtained was observed, the thickness of the copper layer was 3 μm. When the obtained particles were further sieved with a sieve having an opening of 350 μm, less than 1% of the total weight remained on the sieve, and no large aggregation was observed. Observation with a microscope of 2,000 of these particles revealed that the appearance was a glossy copper color, and that about 2% of the particles had cracks or peeling.

Example 2 Polymerization was carried out in the same manner as in Example 1 by using divinylbenzene and a tetrafunctional acrylic monomer on the base particles, and the center particle diameter was 30%.
0 μm particles were obtained. Nickel plating was formed thereon by electroless plating as a conductive underlayer. With the same formulation, nickel-plated dummy particles having a center particle diameter of 800 μm and synthesized with divinylbenzene and a tetrafunctional acrylic monomer were obtained.

Then, 40 g of nickel-plated particles and 20 mL of 800 μm dummy particles were charged into a rotary plating apparatus and copper plating was performed. The plating conditions were as follows: bath temperature 30 ° C., current density 0.5 A / dm ² ,
The rotation direction was reversed every 40 seconds at a peripheral speed of 18 Hz.

The obtained particles were sieved with a sieve having an opening of 700 μm to separate 800 μm dummy particles and plating particles. When the cross section of the plating particles thus obtained was observed, the thickness of the copper layer was 3 μm. When the obtained particles were further sieved with a sieve having an opening of 350 μm, less than 1% of the total weight remained on the sieve, and no large aggregation was observed. Observation with a microscope of 2,000 of these particles revealed that the appearance was a glossy copper color, and that about 2% of the particles had cracks or peeling.

Example 3 In the same manner as in Example 1, particles having a central particle diameter of 300 μm were obtained. Nickel plating was formed thereon by electroless plating as a conductive underlayer. With the same formulation, the central particle size 2
000 μm nickel-plated dummy particles were synthesized. Next, 40 g of 300 μm particles and 2000 μm dummy particles 3 nickel-plated in a rotary plating apparatus.
0 mL and copper plating was performed. The plating conditions were as follows: bath temperature 30 ° C., current density 0.5 A / dm ² , peripheral speed 1
At 8 Hz, the rotation direction was reversed every 40 seconds.

The obtained particles were sieved with a sieve having an opening of 1500 μm to separate 2000 μm dummy particles and plating particles. When the cross section of the plating particles thus obtained was observed, the thickness of the copper layer was 3 μm. When the obtained particles were further sieved with a sieve having an opening of 350 μm, about 1% of the total weight remained on the sieve, and no large aggregation was observed. When 2,000 of these particles were observed with a microscope, the appearance showed a glossy copper color, and the particles with cracks and peeling were:
It was about 2% of the whole.

Example 4 In the same manner as in Example 1, particles having a central particle diameter of 300 μm were obtained. Nickel plating was formed thereon by electroless plating as a conductive underlayer. With the same formulation, the central particle size is 5
00 μm nickel-plated dummy particles were synthesized.
Then, nickel plating was applied to the rotary plating apparatus.
40 g of 0 μm particles and 20 mL of 500 μm dummy particles
And copper plating was performed. The plating conditions were as follows: bath temperature 30 ° C., current density 0.5 A / dm ² , peripheral speed 18 Hz.
The rotation direction was reversed every 40 seconds.

The obtained particles were sieved with a sieve having an opening of 450 μm to separate 500 μm dummy particles and plating particles. When the cross section of the plating particles thus obtained was observed, the thickness of the copper layer was 3 μm. When the obtained particles were further sieved with a sieve having an opening of 350 μm, less than 1% of the total weight remained on the sieve, and no large aggregation was observed. Observation with a microscope of 2,000 of these particles revealed that the appearance was a glossy copper color, and that about 2% of the particles had cracks or peeling.

Example 5 In the same manner as in Example 1, particles having a center particle diameter of 500 μm were obtained. Nickel plating was formed thereon by electroless plating as a conductive underlayer. With the same prescription, nickel-plated dummy particles having a center particle diameter of 800 μm were synthesized. Next, 40 g of 500 μm particles and 800 μm dummy particles 20 which were nickel-plated on a rotary plating apparatus.
mL, and copper plating was performed. The plating conditions were as follows: bath temperature 30 ° C., current density 0.5 A / dm ² , peripheral speed 1
At 8 Hz, the rotation direction was reversed every 40 seconds.

The obtained particles were sieved with a sieve having an opening of 700 μm to separate 800 μm dummy particles and plating particles. Observation of the cross section of the plating particles obtained in this way revealed that the thickness of the copper layer was 2 μm. When the obtained particles were further sieved with a sieve having an opening of 450 μm, only about 1% of the total weight remained on the sieve, and no large aggregation was observed. Observation with a microscope of 2,000 of these particles revealed that the appearance was a glossy copper color, and that about 2% of the particles had cracks or peeling.

Example 6 In the same manner as in Example 1, particles having a central particle diameter of 100 μm were obtained. Nickel plating was formed thereon by electroless plating as a conductive underlayer. With the same formulation, nickel-plated dummy particles having a center particle diameter of 500 μm were synthesized. Next, 40 g of 100 μm particles and 500 μm dummy particles 20 which were nickel-plated in a rotary plating apparatus.
mL, and copper plating was performed. The plating conditions were as follows: bath temperature 30 ° C., current density 0.5 A / dm ² , peripheral speed 1
At 8 Hz, the rotation direction was reversed every 40 seconds.

The obtained particles were sieved with a sieve having an opening of 450 μm to separate 500 μm dummy particles and plating particles. Observation of the cross section of the plating particles obtained in this way revealed that the thickness of the copper layer was 2 μm. When the obtained particles were further sieved with a sieve having an opening of 150 μm, only about 1% of the total weight remained on the sieve, and no large aggregation was observed. When 2,000 of these particles were observed with a microscope, the appearance was a glossy copper color, and particles having cracks or peeling were about 1% of the whole.

Example 7 In the same manner as in Example 6, particles having a central particle diameter of 100 μm were obtained. Nickel plating was formed thereon by electroless plating as a conductive underlayer. With the same prescription, nickel-plated dummy particles having a center particle diameter of 2000 μm were synthesized. Next, 40 g of 100 μm particles and 2000 μm dummy particles 3 which were nickel-plated in a rotary plating apparatus.
0 mL and copper plating was performed. The plating conditions were as follows: bath temperature 30 ° C., current density 0.5 A / dm ² , peripheral speed 1
At 8 Hz, the rotation direction was reversed every 40 seconds.

The obtained particles were sieved with a sieve having an opening of 1500 μm to separate 2000 μm dummy particles and plating particles. Observation of the cross section of the plating particles obtained in this way revealed that the thickness of the copper layer was 2 μm. When the obtained particles were further sieved with a sieve having an opening of 150 μm, 2% of the total weight remained on the sieve.
%, And no large aggregation was observed. When 2,000 of these particles were observed with a microscope, the appearance was a glossy copper color, and particles having cracks or peeling were about 1% of the whole.

Example 8 In the same manner as in Example 1, particles having a central particle diameter of 50 μm were obtained. Nickel plating was formed thereon by electroless plating as a conductive underlayer. With the same formulation, the central particle size is 5
00 μm nickel-plated dummy particles were synthesized.
Then, nickel plating was applied to the rotary plating apparatus.
Then, 40 g of the μm particles and 30 mL of the 500 μm dummy particles were charged, and copper plating was performed. The plating conditions were as follows: the bath temperature was 30 ° C., the current density was 0.5 A / dm ² , the peripheral speed was 18 Hz, and the rotation direction was reversed every 40 seconds.

The obtained particles were sieved with a sieve having an opening of 450 μm to separate 500 μm dummy particles and plating particles. Observation of the cross section of the plating particles obtained in this way revealed that the thickness of the copper layer was 2 μm. When the obtained particles were further sieved with a sieve having an opening of 100 μm, only about 4% of the total weight remained on the sieve, and no large aggregation was observed. When 2,000 of these particles were observed with a microscope, the appearance was a glossy copper color, and particles having cracks or peeling were about 1% of the whole.

Example 9 40 g of copper-plated particles having a central particle diameter of 304 μm obtained in Example 1 and 20 mL of nickel-plated dummy particles having a central particle diameter of 800 μm also obtained in Example 1 were charged. Crystal solder plating was performed. The plating conditions were as follows: bath temperature 30 ° C., current density 0.5 A / dm ² , peripheral speed 1
At 8 Hz, the rotation direction was reversed every 20 seconds. The obtained particles are sieved with a sieve having an opening of 700 μm,
00 μm dummy particles and plating particles were separated. Upon observing the cross section of the plating particles thus obtained,
The thickness of the eutectic solder layer was 6 μm. When the obtained particles were further sieved with a sieve having an opening of 350 μm, only about 2% of the total weight remained on the sieve, and no large aggregation was observed. When 2,000 of these particles were observed with a microscope, the appearance was shiny copper color, and the particles with cracks and peeling were 2% of the total.
%.

Comparative Example 1 In the same manner as in Example 1, particles having a central particle diameter of 300 μm were obtained. Nickel plating was formed thereon by electroless plating as a conductive underlayer. Next, only 40 g of nickel-plated 300 μm particles were charged into a rotary plating apparatus, and copper plating was performed. The plating conditions were bath temperature 30.
° C, current density 0.5A / dm ² , peripheral speed 18Hz
The rotation direction was reversed every 40 seconds.

When the cross section of the plating particles thus obtained was observed, the thickness of the copper layer was 3 μm. When the obtained particles were further sieved with a sieve having an opening of 350 μm, about 10% of the total weight remained on the sieve.
%, And large aggregation of about 2 mm square was observed. When 2,000 of these particles were observed with a microscope, the appearance was a glossy copper color, and particles having cracks or peeling were about 1% of the whole.

Comparative Example 2 In the same manner as in Example 6, particles having a central particle diameter of 100 μm were obtained. Nickel plating was formed thereon by electroless plating as a conductive underlayer. Subsequently, only 40 g of nickel-plated 100 μm particles were charged into a rotary plating apparatus, and copper plating was performed. The plating conditions were bath temperature 30.
° C, current density 0.5A / dm ² , peripheral speed 18Hz
The rotation direction was reversed every 40 seconds.

When the plating particles thus obtained were observed in cross section, the thickness of the copper layer was 2 μm. When the obtained particles were further sieved with a sieve having an opening of 350 μm, about 20% of the total weight remained on the sieve.
%, And large aggregation of about 5 mm square was observed. When 2,000 of these particles were observed with a microscope, the appearance was a glossy copper color, and particles having cracks or peeling were about 1% of the whole.

Comparative Example 3 Particles having a central particle diameter of 300 μm were obtained in the same manner as in Example 1. Nickel plating was formed thereon by electroless plating as a conductive underlayer. Next, 40 g of particles having a central particle diameter of 100 μm and subjected to nickel plating in a rotary plating apparatus.
And 20 mL of zirconia balls with a central particle diameter of 1000 μm
And copper plating was performed. The plating conditions were as follows: bath temperature 30 ° C., current density 0.5 A / dm ² , peripheral speed 18 Hz.
The rotation direction was reversed every 40 seconds.

The obtained particles were sieved with a sieve having an opening of 900 μm to separate 1000 μm dummy particles and plating particles. When the cross section of the plating particles thus obtained was observed, the thickness of the copper layer was 3 μm. When the obtained particles were further sieved with a sieve having an opening of 350 μm, 1% of the total weight remained on the sieve.
And no large aggregation was observed. Observation of 2,000 of these particles with a microscope revealed that the appearance was matte copper color, and that about 40% of the particles had cracks or peeling.

Comparative Example 4 Particles having a central particle diameter of 300 μm were obtained in the same manner as in Example 1. Nickel plating was formed thereon by electroless plating as a conductive underlayer. Next, 40 g of particles having a central particle diameter of 300 μm and plated with nickel in a rotary plating apparatus.
And 20 mL of stainless steel balls with a central particle diameter of 1000 μm
And copper plating was performed. The plating conditions were as follows: bath temperature 30 ° C., current density 0.5 A / dm ² , peripheral speed 18 Hz.
The rotation direction was reversed every 40 seconds.

The obtained particles were sieved with a sieve having an opening of 900 μm to separate 1000 μm dummy particles and plating particles. When the cross section of the plating particles thus obtained was observed, the thickness of the copper layer was 3 μm. When the obtained particles were further sieved with a sieve having an opening of 350 μm, 1% of the total weight remained on the sieve.
And no large aggregation was observed. Observation of 2,000 of these particles with a microscope revealed that the appearance was matte copper color, and that about 40% of the particles had cracks or peeling.

[0051]

Since the present invention has the above-described structure,
Conductive fine particles of up to 1000 μm can be synthesized without aggregation and with good plating surface conditions, and a conductive connection structure having excellent conductivity can be provided using this.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example 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

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) C25D 21/10 302 C25D 21/10 302 F term (reference) 4K024 AA09 AA22 AB02 AB17 BA12 BB10 BC08 CA15 CB01 CB02 CB06 CB08 GA16

Claims (5)

[Claims] 1. A method for plating fine particles, comprising: a rotatable dome having a cathode on an outer periphery thereof and having a filter portion for passing and discharging a plating solution; And a rotating plating apparatus that repeats energization and stirring while contacting the fine particles with the cathode by centrifugal force due to the rotation of the dome, and has the same hardness as the base particles to be plated. Having a particle size of 1.5 to 3 of the base particles to be plated.
A plating method of fine particles, wherein plating is performed by simultaneously adding dummy particles of 0 times. 2. The method for plating fine particles according to claim 1, wherein the base particles to be plated are resin, and the particle diameter is 1 to 1000 μm. 3. The method according to claim 1, wherein the dummy particles are made of a resin. 4. A conductive fine particle plated by the method for plating fine particles according to claim 1, 2 or 3. 5. A conductive connection structure which is connected by the conductive fine particles according to claim 4.