JP2008103343A - Conductive fine particulate, board constituent, and fine particulate soldering method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive fine particulate having an ability for easing a force applied to circuitry including a board, and a method for keeping the distance between boards constant. <P>SOLUTION: The conductive fine particulate is made by coating the surface of a base material particulate made of a resin with one or more metal layers. The resin has a thermal decomposition temperature of 300°C or higher, and at least one of metals composing the metal layer is an alloy and/or metal having a melting point of 150 to 300°C. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a conductive fine particle that is used to connect two or more electrodes of an electric circuit and has improved connection reliability by relaxing a force applied in the circuit, and a substrate structure.

Conventionally, in order to connect ICs and LSIs on electronic circuit boards, a method of soldering each pin on a printed circuit board has been used, but this method is inferior in production efficiency and increases the density. Was unsuitable.

In order to improve the connection reliability, a technology such as BGA (ball grid array) for connecting substrates with so-called solder balls having a spherical solder shape has been developed. According to this technology, an electronic circuit can be manufactured while achieving both high productivity and high connection reliability by connecting a substrate, a chip, and a solder ball mounted on the substrate while melting at a high temperature. I was able to.

However, recently, the number of multilayered substrates has increased, and distortion and expansion / contraction due to changes in the external environment of the substrate itself have occurred. As a result, these forces are applied to the connection part between the substrates, causing disconnection. Yes. In addition, it becomes difficult to maintain the distance between the substrates due to the multi-layered structure, and there is a problem that a separate spacer or the like has to be placed in order to maintain this distance, which is troublesome and expensive.

As means for solving these problems, the force applied to the circuit such as the board is reinforced by applying resin or the like to the board connection part, which is to improve the connection reliability. Although a certain effect was shown, there is a problem that it takes time and costs increase due to an increase in the coating process. Also, for maintaining the distance between the substrates, by using a ball coated with solder around copper, copper that does not melt like solder is supported, and the distance between the substrates can be maintained. . However, since copper is expensive and heavy, an inexpensive and lightweight material is required.

An object of the present invention is to provide a conductive fine particle having an ability to relieve a force applied to a circuit such as a substrate, and a method for maintaining a constant distance between the substrates.

The reference invention is a conductive fine particle in which the surface of a substrate fine particle made of resin is covered with one or more metal layers, and the linear expansion coefficient of the resin is 3 × 10 ^{−5 to} 7 × 10 ⁻⁵ ( 1 / K).
1st this invention is the electroconductive fine particles by which the surface of the base-material microparticles | fine-particles which consist of resin is covered with one or more metal layers, The thermal decomposition temperature of the said resin is 300 degreeC or more, and the said Conductive fine particles in which at least one of the metals constituting the metal layer is an alloy and / or metal having a melting point of 150 to 300 ° C.
The second aspect of the present invention is conductive fine particles in which the surface of the substrate fine particles made of resin is covered with one or more metal layers, and the thermal expansion coefficient of all the layers of the metal layers is 1 × 10. ^{−5 to} 3 × 10 ⁻⁵ (1 / K), and the ratio of the thermal expansion coefficient between each metal layer and the above-mentioned base particle (thermal expansion coefficient of the base particle / thermal expansion coefficient of the metal layer) is The conductive fine particles are 0.1 to 10, respectively.
A third aspect of the present invention is a method for plating fine particles in which the surface of a fine particle of a substrate is covered with at least two kinds of metal alloy layers, wherein the metal alloy layer is obtained by depositing at least one kind of metal by electroplating. There is a fine particle plating method in which at least another kind of metal is formed by incorporating a metal in a dispersed state into a plating bath.
4th this invention is the electroconductive fine particle by which the surface of base-material microparticles | fine-particles is covered with one or more metal layers, Comprising: At least 1 layer is 2 or more metal layers among the said metal layers. It is the electroconductive fine particle which is an alloy layer obtained by thermally diffusing.
5th this invention is a fine particle plating method, Comprising: A rotatable dome which has a cathode in an outer peripheral part and has a filter part which lets a plating solution pass and discharges, It contacts with this cathode in this dome A rotating plating apparatus that repeats energization and stirring while bringing the fine particles into contact with the cathode by the centrifugal force generated by the rotation of the dome, and is equivalent to the base fine particles to be plated. This is a method of plating fine particles in which plating is performed by simultaneously adding dummy particles having hardness and a particle size of 1.5 to 30 times that of the fine particles of the substrate to be plated.
The present invention is described in detail below.

The reference invention, the first invention, and the second invention are conductive fine particles in which the surface of the substrate fine particles made of resin is covered with one or more metal layers.

The resin used in the reference invention has a linear expansion coefficient of 3 × 10 ^{−5 to} 7 × 10 ⁻⁵ (1 / K). In addition, the said linear expansion coefficient is measured about 60-280 degreeC by the compression load method. If the linear expansion coefficient is less than 7 × 10 ⁻⁵ , the resin is generally hardened, so the stress relaxation effect is small, and if it exceeds 3 × 10 ⁻⁵ , the deformation of the resin is large and the circuit distortion is ignored. Can not. In the conductive fine particles of the reference invention, since the linear expansion coefficient of the resin used for the base fine particles is within the above range, the distance between the substrates can be kept constant without being affected by the temperature change.

The resin used in the first invention has a thermal decomposition temperature of 300 ° C. or higher. The thermal decomposition temperature is measured using TGA (thermogravimetric analysis) and is a temperature at which the weight loss of the object starts. When the thermal decomposition temperature is less than 300 ° C., when the temperature of the substrate or the like rises due to conduction, the conductive fine particles are damaged, and conduction cannot be ensured.
The resin used in the reference invention, the first invention, and the second invention is not particularly limited as long as the above conditions are satisfied. For example, a phenol resin, an amino resin, an acrylic resin, a polyester resin, Examples include urea resins, melamine resins, alkyd resins, polyimide resins, urethane resins, epoxy resins and other crosslinked or non-crosslinked synthetic resins; organic-inorganic hybrid polymers. These may be used alone or two or more of them may be used in combination as a copolymer or the like.

The metal layer in the reference invention, the first invention, and the second invention is not particularly limited. For example, gold, silver, copper, platinum, zinc, iron, lead, tin, aluminum, cobalt, indium, nickel, Examples thereof include those made of at least one metal selected from the group consisting of chromium, antimony, bismuth, germanium, cadmium, and silicon. The metal layer may be composed of one layer or may be composed of multiple layers, and these metals may be used alone or in combination of two or more. When two or more kinds of the above metals are used in combination, they may be used to form a plurality of layered structures, or may be used as an alloy.

In the first aspect of the present invention, at least one of the metals constituting the metal layer is an alloy and / or metal having a melting point of 150 to 300 ° C. When at least one of the metals constituting the metal layer is an alloy and / or metal having a melting point of 150 to 300 ° C., the alloy and / or metal melts to absorb the distortion and shrinkage of the substrate caused by the rise in temperature. In addition, the force applied between the substrates can be reduced. Although it does not specifically limit as an alloy and / or metal with melting | fusing point 150-300 degreeC, Among the metals and alloys enumerated above, solder alloy, tin, etc. correspond.

In the second aspect of the present invention, the thermal expansion coefficients of all the metal layers are 1 × 10 ^{−5 to} 3 × 10 ⁻⁵ (1 / K), respectively, and the heat of each metal layer and the substrate fine particles The ratio of the expansion coefficients (the thermal expansion coefficient of the substrate fine particles / the thermal expansion coefficient of the metal layer) is 0.1 to 10, respectively. Since the conductive fine particles of the second aspect of the present invention satisfy the above-mentioned conditions, the metal layer is not destroyed by the expansion / contraction of the base fine particles even when the temperature changes, and the base fine particles and the metal layer are not destroyed. Connection stability can be ensured without peeling.

When the outer diameter of the conductive fine particles of the reference invention, the first invention and the second invention is 200 to 1000 μm, the thickness of the metal layer is 0.5 to 30% of the radius of the substrate fine particles. It is preferable. If it is less than 0.5%, the durability during transport of the conductive fine particles and the initial connection reliability may be lowered, and if it exceeds 30%, the stress relaxation effect may be lowered. When the thickness of the metal layer is within the above range with respect to the radius of the base fine particles, the stress relaxation effect of the conductive fine particles and the durability of the particles themselves are the strongest.

Furthermore, it is preferable that the thickness of the metal layer has a relationship represented by the following formula (1) with respect to the radius of the base particle.
Y = (− 25 / 100,000 · X + c) × 100 (1)
In the formula, Y represents the ratio (%) of the thickness of the metal layer to the radius of the substrate fine particles, X represents the outer diameter (μm) of the conductive fine particles, and c represents a constant of 0.10 to 0.35. . However, Y> 0.
When the above formula (1) is satisfied, the stress relaxation effect of the conductive fine particles and the durability of the particles themselves become stronger.

When the outer diameter of the conductive fine particles of the reference invention, the first invention, and the second invention is 50 to 200 μm, the thickness of the metal layer is 1 to 100% of the radius of the substrate fine particles. preferable. If it is less than 1%, the durability during transport of particles and the initial connection reliability may be lowered, and if it exceeds 100%, the stress relaxation effect may be lowered. When the thickness of the metal layer is within the above range with respect to the radius of the base fine particles, the stress relaxation effect of the conductive fine particles and the durability of the particles themselves are the strongest. More preferably, it is 4 to 40%.

In the conductive fine particles of the reference invention, the first invention, and the second invention, it is preferable that particles having bubbles in the substrate fine particles are 1% or less of the total number. Particles having bubbles in the substrate fine particles have irregularities on the surface, so that the metal coating is easily peeled off at the portions, which may cause disconnection or the like when mounted on the substrate. In addition, bubbles expand during heating such as reflow, which causes micro cracks in solder and the like. Since bubbles cause disconnection and microcracks, the smaller the number of particles with bubbles, the better. However, if it exceeds 1%, the defect rate cannot be ignored, which is not preferable. More preferably, it is 0.5% or less.

Furthermore, when the outer diameter of the base fine particles of the conductive fine particles of the reference invention, the first invention and the second invention is 50 to 1000 μm, bubbles having a diameter of 1% or more of the radius of the base fine particles It is preferable that a certain particle is 1% or less of the total number.

Similarly to the bubbles, when the substrate fine particles contain a substance having a boiling point of 300 ° C. or less, such as water, it expands during heating such as reflow and causes micro cracks in the solder. For this reason, in the conductive fine particles of the reference invention, the first invention, and the second invention, the total of substances having a boiling point of 300 ° C. or less such as water contained in the substrate fine particles is 1 of the total weight of the particles. It is preferable that it is less than weight%. If it exceeds 1% by weight, the defective rate is not negligible, which is not preferable.

The conductive fine particles of the reference invention, the first invention, and the second invention preferably have a sphericity of 1.5% or less. The sphericity is a parameter represented by the following formula (2).
Sphericality (%) =
(Maximum diameter of sphere−minimum diameter of sphere) / (maximum diameter of sphere + minimum diameter of sphere) × 2 × 100 (2)
When the sphericity is 1.5% or less, the handling of the conductive fine particles is good, and the damage during transportation and the damage during the mounting process are small. On the other hand, when the sphericity exceeds 1.5%, there is a lot of damage during transportation, and there is a risk that debris is scattered during the process.

The conductive fine particles of the reference invention, the first invention, and the second invention preferably have a resistance value of 100 mΩ or less. If it is 100 mΩ or less, a module with low power consumption can be manufactured without generating heat in the circuit. If it exceeds 100 mΩ, the power consumption of the module using the conductive fine particles will increase dramatically, and the resulting heat generation is not negligible.

In the conductive fine particles of the reference invention, the first invention, and the second invention, the ratio of the maximum value and the minimum value of E ′ in the temperature range of −60 to 200 ° C. of the substrate fine particles is 1-2. It is preferable. If the ratio between the maximum value and the minimum value in the above temperature range is 1 to 2, the change in viscoelasticity is small, and even when used for mounting, there is little deterioration of the product due to heat. However, if it exceeds a predetermined ratio, the product may be damaged or deteriorated when the viscoelasticity is lowered.

In the conductive fine particles of the reference invention, the first invention, and the second invention, the K value of the substrate fine particles is preferably 1000 to 10,000 (MPa). The above K value (MPa) is intended to mean the compression hardness at 10% deformation, expressed in ^{(3 / √2) · F ·} S -3/2 · R -1/2, F is The load value (MPa × mm ² ) at 20 ° C. and 10% compression deformation, S is the compression displacement (mm), and R is the value expressed by the radius (mm). Compressed with a smooth end face of a 50 μm diameter cylinder made of diamond with a compression hardness of 0.27 g / sec and a maximum test load of 10 g using a micro compression tester (PCT-200, manufactured by Shimadzu Corporation) This is a calculated value. The smaller the K value, the easier the deformation. If the K value is less than 1000 MPa, it may be too flexible to cause problems such as bonding at the time of manufacture, and the gap between the substrates may not be maintained, and a collision may occur at a portion other than the bonded portion between the substrates. It is not practical, and when it exceeds 10,000 MPa, it is too hard, and when used for bonding between substrates, stress is easily applied to the bonded portion. More preferably, it is 1500-6500 (MPa).

In the conductive fine particles of the reference invention, the first invention, and the second invention, the metal layer is preferably composed of 2 to 4 layers, and the outermost layer is preferably a solder alloy and / or tin. The outer diameter of the substrate fine particles can be appropriately selected according to the application. For example, the substrate fine particles having outer diameters of 700 to 800 μm, 250 to 400 μm, and 50 to 150 μm can be used.
The outer diameter of the substrate fine particles is 700 to 800 μm, the metal layer is composed of four layers, the innermost layer is a nickel layer of 0.1 to 0.5 μm, the outer layer is a copper layer of 2 to 12 μm, and the outer layer is 2 to 2 Conductive fine particles having a solder alloy layer in which lead of 30 μm is 82 to 98%, tin is 2 to 18%, outermost layer is 25 to 50% of lead of 2 to 30 μm, and solder alloy layer of 50 to 75% of tin When used, the strain and shrinkage of the substrate caused by the temperature rise can be absorbed and the force applied between the substrates can be reduced.

A substrate structure in which two or more substrates are connected by the conductive fine particles of the reference invention, the first invention, or the second invention is also one aspect of the present invention.

The conductive fine particles used in the substrate structure preferably have a CV value of 1.5% or less of the particle size of the base fine particles. The CV value is expressed by the following formula (3).
CV value = (σ / Dn) × 100 (3)
In the formula, σ represents the standard deviation of the particle diameter, and Dn represents the number average particle diameter. The standard deviation and the number average particle diameter are values obtained by observing and measuring 100 arbitrary conductive fine particles with an electron microscope. When the CV value exceeds 1.5%, the dispersion of the particle size increases, so when joining the electrodes via the conductive fine particles, the number of conductive fine particles not involved in the joining increases, and a leak phenomenon occurs between the electrodes. May happen.

It is preferable that the conductive fine particles used in the substrate structure have a base particle size of ± 5% of the center value. Similarly, when the value is outside the range of ± 5%, the variation in the particle size becomes large. Therefore, when the electrodes are joined via the conductive fine particles, the number of conductive fine particles not involved in the joining increases, Leakage may occur.

In the substrate structure, the distance between the substrates is preferably 95 to 120% of the particle size of the conductive fine particles of the present invention. If it is less than 95%, the substrate may be damaged, and if it exceeds 120%, the connection stability may be lowered.

In the above-described substrate structure, the materials and / or compositions constituting two or more substrates may be the same or different. Even if the plurality of substrates constituting the substrate structure are different from each other, by connecting using the conductive fine particles of the present invention, a circuit such as a substrate generated by distortion or expansion / contraction due to a change in the external environment of the substrate itself can be obtained. The applied force can be reduced.

In the substrate structure, the difference in linear expansion coefficient between the substrates may be 10 ppm or more. Even if it is 10 ppm or more, the force applied to a circuit such as a substrate generated by distortion or expansion / contraction due to a change in the external environment of the substrate itself can be reduced by connecting with the conductive fine particles of the present invention.

The third aspect of the present invention is a method for plating fine particles in which the surface of the substrate fine particles is covered with at least two kinds of metal alloy layers.
The metal alloy layer according to the third aspect of the present invention is formed by depositing at least one kind of metal by electroplating and incorporating at least another kind of metal in a dispersed state in the plating bath. It is characterized by being.

The conductive fine particles obtained by the third aspect of the present invention are those in which the surface of the base fine particles made of resin and metal balls is covered with two or more metal alloy layers. Examples of the resin include polystyrene, polystyrene copolymer, polyacrylate ester, polyacrylate ester polymer, phenol resin, polyester resin, and polyvinyl chloride. These may be used independently and 2 or more types may be used together. The shape of the substrate fine particles is not particularly limited as long as it is spherical, and may be, for example, a hollow shape. Examples of the metal balls include high melting point metals such as silver, copper, nickel, silicon, gold, and titanium.

Although the average particle diameter of these substrate fine particles is not particularly limited, considering the usage of the mounting material such as BGA and CSP, those having a particle diameter of 1 to 1000 μm are useful and preferable.

The conductive fine particles of the present invention are those obtained by coating the above-mentioned substrate fine particles with two or more metal alloy layers. Examples of the metal to be coated include gold, silver, copper, platinum, zinc, iron, tin, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, cadmium, silicon, and the like.

One kind of these metals may be used, or a plating layer may be formed as an alloy composition comprising two or more kinds. For example, the structure etc. which plate a nickel layer on the base-material fine particle which consists of polystyrene resin, and also provide a tin-silver alloy layer on it are mentioned.

Of these metal layers, at least one layer is preferably an alloy layer plated by a composite plating method. In the composite plating layer, plating compositions such as tin-silver, tin-copper, and tin-silver-copper centered on tin can be cited in order to meet recent lead-free requirements. In particular, it is preferable to use tin-silver from the practical results and the condition of the plating bath.

The thickness of the metal layer is not particularly limited, but is preferably 0.01 to 500 μm in consideration of applications such as conductive bonding and substrate bonding. If it is less than 0.01 μm, it is difficult to obtain preferable conductivity, and if it exceeds 500 μm, the particles may coalesce, and the function of maintaining the distance between the substrates and relaxing the force applied to the circuit such as the substrate may be deteriorated. .

In the third aspect of the present invention, for example, by using a plating bath containing a divalent tin compound, a monovalent silver compound, and a eutectoid stabilization aid as a basic composition, electroplating tin of the alloy composition as ions, It is possible to deposit in the plating film as metallic silver in which silver is dispersed in the plating bath.
In the plating bath, metallic silver particles are spontaneously generated by the reaction of the following formula, which is a decomposition reaction.
Sn2 ⁺ 2 + 2Ag ⁺ → ^Sn4 ++ 2Ag ↓

In this case, the silver particles are generated in the plating bath with a particle size of about 5 nm, and it has been confirmed that they exist stably without aggregation and sedimentation.

That is, the plating method of the present invention is essentially different from the conventional tin-silver alloy film plating method in which tin ions and silver ions are simultaneously reduced and alloyed on the cathode, so that the deposition potential of tin and silver is different. Can solve all the conventional problems caused by being far away. Therefore, there is no disadvantage that silver, which is a noble component at a low current density, is preferentially precipitated and the alloy composition of the plating film becomes non-uniform.

Further, on the same principle, even with an alloy composition such as tin-copper having a separated deposition potential, the coating composition can be adjusted at a low current density by the composite plating method.

As the divalent tin compound used in the third aspect of the present invention, any known non-cyanide compounds can be used. For example, tin sulfate, tin chloride, tin bromide, tin oxide, tin borofluoride, silicon fluoride Organic acid salts and inorganic acid salts such as tin fluoride, tin sulfamate, tin oxalate, tin tartrate, tin gluconate, tin pyrophosphate, tin methanesulfonate and tin alkanolsulfonate can be used.

The amount of the tin compound used is suitably 5 to 100 g / L, preferably 10 to 20 g / L, as the tin content. And said tin compound may use 2 or more types together.

Examples of the eutectoid stabilization aid used in the third aspect of the present invention include the following.
(A) Aliphatic dicarboxylic acids having 0 to 4 carbon atoms in the alkyl group: succinic acid, malonic acid, glutaric acid, adipic acid.
(B) Aliphatic oxycarboxylic acid: glycolic acid, lactic acid, malic acid, tartaric acid, citric acid, gluconic acid, glucoheptonic acid.
(C) Condensed phosphoric acid: pyrophosphoric acid and tripolyphosphoric acid.
(D) Amine carboxylic acid: ethylenediaminetetraacetic acid (EDTA), iminodiacetic acid, nitrilotriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetramine hexaacetic acid.

The amount of these eutectoid stabilizing aids can be appropriately selected depending on the type of additive compound used, but in order to keep the divalent tin compound stable in the aqueous solution, the amount of tin contained in the plating bath is 1 mol. It is preferable to use 1 mol or more. More preferably, it is 2 to 5 mol. Two or more of the above compounds may be used in combination.

As the monovalent silver compound used in the plating bath of the third aspect of the present invention, any known non-cyanide can be used. For example, silver oxide, silver nitrate, silver sulfate, silver chloride, silver sulfamate, citric acid Silver, silver lactate, silver pyrophosphate, silver methanesulfonate, silver alkanol sulfonate and the like can be used.

The amount of the silver compound used is preferably 2 to 50 g / L, and more preferably 2 to 10 g / L. Is preferred. And as a silver compound, you may use 2 or more types of the above compounds together.

In order to control the silver content of the plating film, an amine compound or a salt thereof having an action of increasing the eutectoid amount of silver is added to the plating bath of the third aspect of the present invention. Also good. Any known amine compound can be used. For example, (mono, di, tri) methylamine, (mono, di, tri) ethylamine, (mono, di, tri) butylamine, ethylenediamine, triethyltetraamine, (mono, di, tri) ethanolamine, imidazole, oxine, Bipyridyl, phenanthroline, succinimide and the like can be mentioned. Although the addition amount changes with kinds of used compound, 1-100 g / L is suitable and 2-50 g / L is more suitable. Two or more of these compounds may be used in combination.

Furthermore, as a surface conditioner for giving gloss to the surface of the tin-silver alloy film obtained by electrolysis from the plating bath of the third invention, for example, polyethylene glycol, polyoxyethylene alkylphenyl ether, polyoxy Ethylene alkyl ethers and polyoxyethylene fatty acid esters may be used.

Polyethylene glycol having any molecular weight can be used. For example, those having an average molecular weight of 200 to those having an average molecular weight of 4 million can be used. And the usage-amount is 0.1-50 g / L suitably, More preferably, it is 0.2-5 g / L. Further, at least one selected from polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ether, and polyoxyethylene fatty acid ester can be used. These surface conditioners are also used in the plating bath in the range of 0.2 to 10 g / L.

The plating method of the third aspect of the present invention is not particularly limited, but for particles of 500 μm or less, a cathode is provided on the outer periphery, the plating solution and the plating substrate fine particles are held inside the main body, and energized while rotating. From the viewpoint of uniformity and agglomeration, it is preferable to perform plating with a rotary plating apparatus that repeats stirring (hereinafter referred to as a rotary plating apparatus).

A schematic diagram of an example of this rotary plating apparatus is shown in FIG. The plating apparatus A includes a disk-shaped plastic bottom plate 11 fixed to the upper end portion of the vertical drive shaft 3 and a porous ring 13 as a filter portion through which only the processing liquid passes on the outer peripheral upper surface of the bottom plate 11. A contact ring 12 for energization is disposed on the upper surface of the porous ring 13 as a cathode, and the porous ring 13 and the contact ring 12 are attached to the bottom plate at the outer peripheral portion of the frustoconical plastic hollow cover 1 having an opening 8 at the upper center. A processing chamber 4 sandwiched between the substrate 11 and the supply pipe 6 for supplying the processing liquid or the like to the processing chamber 4 from the opening 8; and a plastic container for receiving the processing liquid scattered from the porous window. 5, a discharge pipe 7 that discharges the processing liquid accumulated in the container 5, and an anode 2 a that is inserted from the opening 8 and contacts the plating solution.

While rotating the drive shaft 3, the fine particles on which the plating solution and the conductive underlayer are formed are present in the processing chamber 4 so as to be immersed in the plating solution, and between the contact ring 12 (cathode) and the anode 2a. Energize. 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 is stopped, the fine particles are dragged by the flow of gravity and the inertia of the plating solution, and flow down to the flat surface of the central portion of the bottom plate, and are mixed with each other. 12, 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 way, plating is uniformly performed on all the fine particles present in the processing chamber 4.

Conductive fine particles obtained by plating using the fine particle plating method of the third aspect of the present invention are also one aspect of the present invention. When the conductive fine particles are used when connecting the electrodes, the force applied in the circuit can be relaxed, and the conductive connection structure is excellent. Such a conductive connection structure is also one aspect of the present invention.

The fourth aspect of the present invention is conductive fine particles in which the surface of the substrate fine particles is covered with one or more metal layers. According to a fourth aspect of the present invention, at least one of the metal layers is an alloy layer obtained by thermally diffusing two or more metal layers.

The substrate fine particles are not particularly limited, and examples thereof include those made of resin, metal, and the like.
Examples of the resin include polystyrene, polystyrene copolymer, polyacrylate ester, polyacrylate ester polymer, phenol resin, polyester resin, and polyvinyl chloride. These may be used alone or in combination of two or more. Examples of the metal include high melting point metals such as silver, copper, nickel, silicon, gold, and titanium.
As the substrate fine particles, those made of resin are suitably used.

The shape of the substrate fine particles is not particularly limited as long as it is spherical, and for example, it may be hollow.

The substrate fine particles preferably have an average particle diameter of 1 to 1000 μm. If it is less than 1 μm, the particle size of the obtained conductive fine particles is too small, and it is difficult to obtain a good connection when connecting the electrodes, and if it exceeds 1000 μm, it is difficult to meet the recent demand for narrow pitch connection. .

Examples of the metal layer include those made of gold, silver, copper, platinum, zinc, iron, tin, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, cadmium, silicon, and the like. .

The thickness of the metal layer is not particularly limited, but is preferably 0.01 to 500 μm in consideration of applications such as conductive bonding and substrate bonding. When the thickness is less than 0.01 μm, it is difficult to obtain preferable conductivity. When the thickness exceeds 500 μm, the conductive fine particles coalesce with each other, and the function of maintaining the distance between the substrates and relaxing the force applied to the circuit such as the substrate is provided. May decrease.

The method for forming the metal layer on the surface of the substrate fine particles is not particularly limited. For example, a method using electroless plating, a method using electroplating, or coating fine particles with a paste obtained by mixing metal fine powder alone or in a binder. And physical vapor deposition methods such as vacuum deposition, ion plating, and ion sputtering.

The conductive fine particles of the fourth aspect of the present invention are characterized in that at least one of the metal layers is an alloy layer obtained by thermally diffusing two or more metal layers.
The alloy layer includes at least two metal layers selected from the group consisting of tin, silver, copper, zinc, bismuth, indium, aluminum, cobalt, nickel, chromium, titanium, antimony, germanium, cadmium, and silicon, It is obtained by thermal diffusion. Among these, an alloy layer obtained by thermally diffusing a metal selected from silver, copper, zinc, bismuth, and indium based on tin is preferable.

The method of thermally diffusing at least two kinds of metal layers is not particularly limited. For example, an alloy layer having a desired metal composition by holding fine particles having a multilayer structure for a certain period of time in a thermostatic bath. Conductive fine particles having can be obtained. In order to suppress oxidative deterioration due to heat, the inside of the thermostatic chamber at the time of heat treatment is preferably an inert atmosphere such as nitrogen or argon, or is thermally diffused in a vacuum state.

The heat treatment temperature is not particularly limited and may be appropriately selected depending on the metal to be diffused. However, the heat treatment temperature is preferably about 20 to 100 ° C. lower than the melting point of the lower melting point metal. For example, when diffusing a multilayer structure of tin and silver, it is preferable to perform thermal diffusion at about 132 to 212 ° C., which is 20 to 100 ° C. lower than 232 ° C. which is the melting point of tin.

Since the alloy layer is obtained by thermally diffusing two or more metal layers, the metal composition of the alloy layer can be easily controlled, and an alloy layer having a desired metal composition can be formed.
The position of the alloy layer is not particularly limited, but is preferably the outermost layer. The outermost layer can be used as a solder layer.

The conductive fine particles of the fourth aspect of the present invention are used as BGA solder balls, anisotropic conductive sheets, anisotropic conductive adhesives for connecting ICs or LSIs on a substrate, and used for bonding substrates or components. .

The method for bonding the substrate or the component is not particularly limited as long as it is a method of bonding using conductive fine particles, and examples thereof include the following methods.
(1) A method in which an anisotropic conductive sheet is placed on a substrate or component having an electrode formed on the surface, and then a substrate or component having the other electrode surface is placed and heated and pressed to join.
(2) A method in which an anisotropic conductive adhesive is supplied and joined by means such as screen printing or a dispenser instead of using an anisotropic conductive sheet.
(3) A method in which a liquid binder is supplied to the gap between two electrode portions bonded together via conductive fine particles and then cured and bonded.

As described above, a joined body of substrates or components, that is, a conductive connection structure can be obtained. Such a conductive connection structure is also one aspect of the present invention.

5th this invention is a fine particle plating method, Comprising: A rotatable dome which has a cathode in an outer peripheral part and has a filter part which lets a plating solution pass and discharges, It contacts with this cathode in this dome A rotating plating apparatus that repeats energization and stirring while bringing the fine particles into contact with the cathode by the centrifugal force generated by the rotation of the dome, and is equivalent to the base fine particles to be plated. Plating is performed by simultaneously adding dummy particles having hardness and a particle size of 1.5 to 30 times that of the substrate fine particles to be plated.

The conductive fine particles obtained in the fifth aspect of the present invention are those in which the surface of the base fine particles made of resin and metal balls is covered with one or more metal layers. The composition of these substrate fine particles is not particularly limited, but is preferably a resin considering the function of providing a stress relaxation function during mounting. Examples of the resin include polystyrene, polystyrene copolymer, polyacrylate ester, polyacrylate ester polymer, phenol resin, polyester resin, and polyvinyl chloride. These may be used independently and 2 or more types may be used together. The shape of the substrate fine particles is not particularly limited as long as it is spherical, and may be, for example, a hollow shape. Examples of the metal ball include high melting point metals such as silver, copper, nickel, silicon, gold, and titanium.

In addition, the particle size of these substrate fine particles is not particularly limited, but considering the usage of mounting materials such as BGA and CSP, those of 1 to 1000 μm are useful, and moreover, they are easily aggregated in a rotary plating apparatus. , Effective for particles of 1 to 500 μm.

The conductive fine particles obtained in the fifth aspect of the present invention are those obtained by coating the above-mentioned substrate fine 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, silicon and the like. One kind of these metals may be used, or a plating layer may be formed as an alloy composition comprising two or more kinds. For example, a configuration in which a nickel layer is plated on polystyrene resin substrate fine particles and copper or tin is further plated thereon.
The thickness of the metal layer is not particularly limited, but is preferably 0.01 to 500 μm in consideration of applications such as conductive bonding and substrate bonding. If it is less than 0.01 μm, it is difficult to obtain preferable conductivity, and if it exceeds 500 μm, the particles may coalesce, and the function of maintaining the distance between the substrates and relaxing the force applied to the circuit such as the substrate may be deteriorated.

The fine particle plating method of the fifth aspect of the present invention includes a rotatable dome having a filter portion for allowing a plating solution to pass through and an anode disposed in the dome so as not to contact the cathode. In addition, a rotary plating apparatus that repeats energization and agitation by bringing the fine particles into contact with the cathode by the effect of centrifugal force generated by the rotation of the dome is used. This is the same as that used in the third aspect of the present invention.

In the fifth aspect of the present invention, at this time, plating is performed by simultaneously adding dummy particles having hardness equivalent to the substrate fine particles to be plated and whose particle size is 1.5 to 30 times that of the substrate fine particles to be plated. I do.

The hardness of the dummy particles is defined by a compressive elastic modulus and is preferably about 200 to 500 ± 100 kgf / mm ² .
That is, it is preferable to use dummy particles having a resin composition without using metals such as stainless steel and iron, and inorganic materials such as zirconia and alumina. Although it does not specifically limit as a resin composition, For example, a polystyrene, a polystyrene copolymer, a polyacrylic acid ester, a polyacrylic acid ester copolymer, a phenol resin, a polyester resin, polyvinyl chloride, nylon etc. are mentioned. These may be used independently and 2 or more types may be used together.

The particle size of the dummy particles is preferably about 1.5 to 30 times that of the substrate fine particles to be plated. If the particle diameter of the dummy particles is smaller than 1.5 times, it is not preferable because it becomes difficult to separate the plated particles and the dummy particles. On the other hand, if it is larger than 30 times, the substrate fine particles to be plated enter into the gaps between the dummy particles, and it is difficult to produce a substantial crushing effect.

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

According to the present invention, it is possible to provide conductive fine particles having an ability to relieve a force applied to a circuit such as a substrate, and a method for maintaining a constant distance between substrates.

Hereinafter, embodiments of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

(Reference Example 1)
A nickel plating layer was formed as a conductive underlayer on the base particles obtained by copolymerizing styrene and divinylbenzene to obtain nickel plating fine particles having an average particle size of 698.5 μm and a standard deviation of 17.5 μm. 30 g of the obtained nickel plating fine particles were taken, copper plating was performed on the surface thereof using a barrel plating apparatus, and eutectic solder plating was further performed thereon.
The plating barrel has a regular pentagonal shape with a diameter of 50 mm and a prismatic shape with a height of 50 mm, and a filter which is a mesh with a pore diameter of 20 μm is applied to only one side surface.
This apparatus was energized in a copper plating solution for 1 hour, and the container was rotated at 50 rpm around an axis passing through the centers of regular pentagons to perform copper plating and cleaning. Thereafter, while energizing in the eutectic solder plating solution for 8 hours, the plating barrel was similarly rotated to perform eutectic solder plating.
The eutectic solder plating resin microparticles whose outermost shell thus obtained was a eutectic solder plating layer were observed with a microscope, and it was confirmed that there was no aggregation and all the particles were present as single particles. It was done. Moreover, as a result of observing and measuring 100 resin particles plated with eutectic solder with a magnifying glass, the average particle size was 749.2 μm and the standard deviation was 18.1 μm. Further, when the cut cross section of the particle was measured under a microscope, the thickness of the Ni plating was calculated to be about 0.3 μm, the thickness of the Cu plating was 5 μm, and the thickness of the eutectic solder plating was 20 μm. The coefficient of variation in particle size was 2.4%.
On the other hand, after the base fine particles before plating were formed into a plate shape, the linear expansion coefficient was measured at 60 to 280 ° C. by a compression load method, and at 60 to 200 ° C., 6.0 × 10 ⁻⁵ (1 / K). It was 4.1 × 10 ⁻⁵ (1 / K) at 200 to 280 ° C.
Also, no scratches or bipolars were found in any of the above plated particles.

(Reference Example 6)
A nickel plating layer was formed as a conductive underlayer on the base material fine particles made of polyurethane resin to obtain nickel plating fine particles having an average particle diameter of 704.5 μm and a standard deviation of 19.8 μm. Taking 30 g of the obtained nickel plating fine particles, the surface thereof was subjected to copper plating in the same manner as in Reference Example 1, and eutectic solder plating was further performed thereon.
The eutectic solder plating resin microparticles whose outermost shell thus obtained was a eutectic solder plating layer were observed with a microscope, and it was confirmed that there was no aggregation and all the particles were present as single particles. It was done. In addition, as a result of observing and measuring 100 resin particles plated with eutectic solder with a magnifier, the average particle size was 755.5 μm and the standard deviation was 25.1 μm. Further, when the cut cross section of the particle was measured under a microscope, the thickness of the Ni plating was calculated to be about 0.3 μm, the thickness of the Cu plating was 5 μm, and the thickness of the eutectic solder plating was 20 μm. The variation coefficient of the particle size was 3.3%.
On the other hand, when the linear expansion coefficient was measured at 60 to 280 ° C. in the same manner as in Reference Example 1, it was 13.5 × 10 ⁻⁵ (1 / K) at 60 to 200 ° C. and 11.7 × at 200 to 280 ° C. 10 ⁻⁵ (1 / K).
Also, no scratches or bipolars were found in any of the above plated particles.

(Reference Example 2)
A nickel plating layer is formed as a conductive underlayer on the base particles obtained by copolymerization of tetramethylolmethane tetraacrylate and divinylbenzene, and nickel plating particles having an average particle diameter of 748.2 μm and a standard deviation of 24.5 μm are obtained. It was. Taking 30 g of the obtained nickel plating fine particles, the surface thereof was subjected to copper plating in the same manner as in Reference Example 1, and eutectic solder plating was further performed thereon.
The eutectic solder plating resin microparticles whose outermost shell thus obtained was a eutectic solder plating layer were observed with a microscope, and it was confirmed that there was no aggregation and all the particles were present as single particles. It was done. Further, as a result of observing and measuring 100 resin particles plated with eutectic solder with a magnifier, the average particle diameter was 800.5 μm and the standard deviation was 24.1 μm. Further, when the cut cross section of the particles was measured under a microscope, the thickness of the Ni plating was calculated to be about 0.3 μm, the thickness of the Cu plating was 6 μm, and the thickness of the eutectic solder plating was 20 μm. The coefficient of variation in particle size was 3.0%.
On the other hand, when the linear expansion coefficient was measured at 60 to 280 ° C. in the same manner as in Reference Example 1, it was 5.4 × 10 ⁻⁵ (1 / K) at 60 to 200 ° C. and 3.7 × at 200 to 280 ° C. 10 ⁻⁵ (1 / K).
Also, no scratches or bipolars were found in any of the above plated particles.

(Reference Example 7)
A nickel plating layer was formed as a conductive underlayer on substrate fine particles made of an ethylene-vinyl acetate copolymer resin to obtain nickel plating fine particles having an average particle size of 748.5 μm and a standard deviation of 23.8 μm. Taking 30 g of the obtained nickel plating fine particles, the surface thereof was subjected to copper plating in the same manner as in Reference Example 1, and eutectic solder plating was further performed thereon.
The eutectic solder plating resin microparticles whose outermost shell thus obtained was a eutectic solder plating layer were observed with a microscope, and it was confirmed that there was no aggregation and all the particles were present as single particles. It was done. Further, as a result of observing and measuring 100 resin particles plated with eutectic solder with a magnifying glass, the average particle size was 800.7 μm and the standard deviation was 26.1 μm. Further, when the cut cross section of the particles was measured under a microscope, the thickness of the Ni plating was calculated to be about 0.3 μm, the thickness of the Cu plating was 6 μm, and the thickness of the eutectic solder plating was 20 μm. The variation coefficient of the particle size was 3.3%.
On the other hand, when the linear expansion coefficient was measured at 60 to 280 ° C. in the same manner as in Reference Example 1, it was 18.9 × 10 ⁻⁵ (1 / K) at 60 to 200 ° C., and 15.4 × at 200 to 280 ° C. 10 ⁻⁵ (1 / K).
Also, no scratches or bipolars were found in any of the above plated particles.

(Reference Examples 3-5)
A material similar to that of Reference Example 2 was prepared, except that the average particle diameter of the base material fine particles of Reference Example 2 was 398.2 μm and the standard deviation was 5.8 μm. This was designated as Reference Example 3.
Similarly, the same material as in Reference Example 2 was prepared except that the average particle size of the substrate fine particles was 122.8 μm and the standard deviation was 1.6 μm. This was designated as Reference Example 4.
In the metal layer of Reference Example 2, the innermost layer is Ni plating, the outer layer is Cu plating, the outer layer is lead 9: tin 1 solder alloy plating (high temperature solder), the outermost layer is eutectic solder plating, and Each of the layers had a measured value on a particle cut surface under a microscope having a Ni plating thickness of about 0.3 μm, a Cu plating thickness of 5 μm, a high temperature solder plating thickness of 10 μm, and a eutectic solder plating thickness of 10 μm. . This was designated as Reference Example 5.

(Reference Examples 8 to 10)
The same material as in Reference Example 7 was prepared, except that the average particle size of the substrate fine particles in Reference Example 7 was 401.2 μm and the standard deviation was 16.2 μm. This was designated as Reference Example 8.
Similarly, a material similar to that of Reference Example 7 was produced except that the average particle size of the substrate fine particles was 135.3 μm and the standard deviation was 4.7 μm. This was designated as Reference Example 9.
In the metal layer of Reference Example 7, the innermost layer is Ni plating, the outer layer is Cu plating, the outer layer is lead 9: tin 1 solder alloy (high temperature solder) plating, the outermost layer is eutectic solder plating, and Each of the layers has a measurement value at a particle cut surface under a microscope of Ni plating thickness of about 0.3 μm, Cu plating thickness of 5 μm, high temperature solder plating thickness of 10 μm, and eutectic solder plating thickness of 10 μm. did. This was designated as Reference Example 10.

(Example 1)
A nickel plating layer is formed as a conductive underlayer on the base particles obtained by copolymerizing tetramethylolmethanetetraacrylate and divinylbenzene, and nickel plating particles having an average particle size of 148.2 μm and a standard deviation of 4.5 μm are obtained. It was. Taking 30 g of the obtained nickel plating fine particles, the surface thereof was subjected to copper plating in the same manner as in Reference Example 1, and eutectic solder plating was further performed thereon.
The eutectic solder plating resin microparticles whose outermost shell thus obtained was a eutectic solder plating layer were observed with a microscope, and it was confirmed that there was no aggregation and all the particles were present as single particles. It was done. Further, as a result of observing and measuring 100 resin particles plated with eutectic solder with a magnifier, the average particle diameter was 175.5 μm and the standard deviation was 6.1 μm. Moreover, when the cut cross section of the particle was measured under a microscope, the thickness of the Ni plating was about 0.3 μm, the thickness of the Cu plating was 3 μm, and the thickness of the eutectic solder plating was 10 μm. The coefficient of variation in particle size was 3.0%.
Further, the bubbles in the synthetic resin substrate fine particles were examined in advance, but bubbles of 1 μm or more were found in 15 out of 10,000 particles.
Further, when the thermal decomposition temperature of the base material fine particles before plating was measured by TGA / TDA, it was 330 ° C. in the air.
Of the above plated particles, no scratches or bipolar were found on any of the particles.

(Comparative Example 1)
A nickel plating layer was formed as a conductive underlayer on the substrate fine particles made of ethylene-vinyl acetate copolymer resin to obtain nickel plating fine particles having an average particle size of 148.5 μm and a standard deviation of 3.8 μm. Taking 30 g of the obtained nickel plating fine particles, the surface thereof was subjected to copper plating in the same manner as in Reference Example 1, and eutectic solder plating was further performed thereon.
The eutectic solder plating resin microparticles whose outermost shell thus obtained was a eutectic solder plating layer were observed with a microscope, and it was confirmed that there was no aggregation and all the particles were present as single particles. It was done. Further, as a result of observing and measuring 100 resin particles plated with eutectic solder with a magnifying glass, the average particle size was 800.7 μm and the standard deviation was 26.1 μm. Moreover, when the cut cross section of the particle was measured under a microscope, the thickness of the Ni plating was about 0.3 μm, the thickness of the Cu plating was 1 μm, and the thickness of the eutectic solder plating was 2 μm. The variation coefficient of the particle size was 3.3%.
Further, the bubbles in the synthetic resin substrate fine particles were examined in advance, but bubbles of 1 μm or more were observed in 63 pieces out of 10,000 pieces.
Also, no scratches or bipolars were found in any of the above plated particles.

(Example 2)
A nickel plating layer is formed as a conductive underlayer on the base particles obtained by copolymerization of tetramethylolmethane tetraacrylate and divinylbenzene, and nickel plating particles having an average particle diameter of 748.2 μm and a standard deviation of 24.5 μm are obtained. It was. Taking 30 g of the obtained nickel plating fine particles, the surface thereof was subjected to copper plating in the same manner as in Reference Example 1, and eutectic solder plating was further performed thereon.
The eutectic solder plating resin microparticles whose outermost shell thus obtained was a eutectic solder plating layer were observed with a microscope, and it was confirmed that there was no aggregation and all the particles were present as single particles. It was done. In addition, as a result of observing and measuring 100 resin particles plated with eutectic solder with a magnifying glass, the average particle size was 800.5 μm and the standard deviation was 24.1 μm. Moreover, when the cut cross section of the particle was measured under a microscope, the thickness of the Ni plating was about 0.3 μm, the thickness of the Cu plating was 6 μm, and the thickness of the eutectic solder plating was 20 μm. The coefficient of variation in particle size was 3.0%.
When E ′ (−60 to 200 ° C.) was measured, the ratio of the maximum value to the minimum value was 1.78, and the resistance value of the particles was 87 mΩ.
In this particle, the thermal expansion coefficient of the substrate fine particles is 9.8 × 10 ⁻⁵ (1 / K), the thermal expansion coefficient of the metal layer is 1.68 × 10 ⁻⁵ (1 / K), and the thermal expansion coefficient of both is The ratio of was 5.83. However, as a metal layer, it measured about copper.
Also, no scratches or bipolars were found in any of the above plated particles.

(Comparative Example 2)
A nickel plating layer was formed as a conductive underlayer on substrate fine particles made of an ethylene-vinyl acetate copolymer resin to obtain nickel plating fine particles having an average particle size of 748.5 μm and a standard deviation of 23.8 μm. Taking 30 g of the obtained nickel plating fine particles, the surface thereof was subjected to copper plating in the same manner as in Reference Example 1, and eutectic solder plating was further performed thereon.
The eutectic solder plating resin microparticles whose outermost shell thus obtained was a eutectic solder plating layer were observed with a microscope, and it was confirmed that there was no aggregation and all the particles were present as single particles. It was done. Further, as a result of observing and measuring 100 resin particles plated with eutectic solder with a magnifying glass, the average particle size was 800.7 μm and the standard deviation was 26.1 μm. Moreover, when the cut cross section of the particle was measured under a microscope, the thickness of the Ni plating was about 0.3 μm, the thickness of the Cu plating was 6 μm, and the thickness of the eutectic solder plating was 20 μm. The variation coefficient of the particle size was 3.3%.
When E ′ (−60 to 200 ° C.) was measured, the ratio of the maximum value to the minimum value was 2.37, and the resistance value of the particles was 137 mΩ.
Also, no scratches or bipolars were found in any of the above plated particles.

(Measurement example)
A total of 24 plated particles of Reference Examples 1 to 10, Examples 1 and 2 and Comparative Examples 1 to 5 were placed on a dummy chip and bonded to a printed circuit board using an infrared reflow apparatus. The joining conditions were 185 ° C. for 1 minute and 245 ° C. for 3 minutes. Thus, the board | substrate which bonded the dummy chip | tip 10 pieces of each was prepared. This was carried out by putting it in a thermostatic chamber that was programmed at -40 to 125 ° C. (each 30 minutes cycle). All spheres were checked for continuity every 100 cycles. Table 1 shows the relationship between the number of cycles in each example and the number of substrates that became non-conductive.

As described above, the number of comparative examples in which conduction cannot be achieved with a relatively fast number of cycles is increasing compared to the examples.

(Example 3)
In a separable flask, 1.3 parts by weight of benzoyl peroxide as a polymerization initiator was uniformly mixed with 20 parts by weight of divinylbenzene, and this was mixed with 20 parts by weight of a 3% aqueous solution of polyvinyl alcohol and 0.5 parts by weight of sodium dodecyl sulfate. Was added and stirred well, and then 140 parts by weight of ion-exchanged water was added. The solution was reacted at 80 ° C. for 15 hours under a nitrogen stream while stirring. The obtained fine particles were washed with hot water and acetone and then subjected to particle selection with a sieve to obtain particles having a center particle size of 710 μm. A nickel plating layer was formed thereon as a conductive underlayer.
Next, the following were prepared as plating solutions. In 25 L of water, 537 g of tin sulfate (SnSO ₄ ), 1652 g of potassium pyrophosphate (K ₄ P ₂ O ₇ ), and 25 g of polyethylene glycol (molecular maximum: 6000) were uniformly dissolved. 42.5 g of silver nitrate (AgNO ₃ ) was added to this solution, and the solution was stirred for 2 hours.
The plating solution was put in a bathtub of a rotary plating apparatus, and 40 g of 710 μm particles plated with nickel were plated. The plating conditions were as follows: the bath temperature was 50 ° C., the current density was 0.5 A / dm ² , the peripheral speed was 18 Hz, and the rotation direction was reversed every 10 seconds.
When the plated particles thus obtained were observed with a microscope, it was confirmed that all the particles were present as single particles without any aggregation. The appearance was silver white, and no discoloration or uneven color was observed.
When this particle was observed in cross section, the film thickness of the outermost layer was 6 μm. Composition analysis of the cut cross section by X-ray microwave analysis confirmed that an Sn layer was present on the Ni underlayer, and Ag was dispersed in the Sn layer. When this plating film was dissolved in a strong acid and the composition ratio was determined by atomic absorption analysis, it was Sn: Ag = 96.0: 4.0, which was close to the tin / silver eutectic composition. Further, when this particle was subjected to thermal analysis by DSC, a melting peak was observed at 221 ° C., which is an alloy melting point of Sn / Ag.

Example 4
Polymerization was performed in the same manner as in Example 3 using divinylbenzene and a tetrafunctional acrylic monomer as the base fine particles to obtain 710 μm particles. Thereafter, plating was performed in the same manner as in Example 3.
When the plated particles thus obtained were observed with a microscope, it was confirmed that all the particles were present as single particles without any aggregation. The appearance was silver white, and no discoloration or uneven color was observed.
When this particle was observed in cross section, the film thickness of the outermost layer was 6 μm. Composition analysis of the cut cross section by X-ray microwave analysis confirmed that an Sn layer was present on the Ni underlayer, and Ag was dispersed in the Sn layer. When this plated coating was dissolved in a strong acid and the composition ratio was determined by atomic absorption analysis, it was Sn: Ag = 96.0: 4.0. Further, when the particles were subjected to thermal analysis by DSC, a melting peak was observed at 221 ° C., which is the Sn / Ag alloy melting point.

(Example 5)
In place of the resin particles, copper balls having a particle diameter of 500 μm were used as the base particles, and a tin-silver plating process was performed in the same manner as in Example 3 using a rotary plating apparatus.
When the plated particles thus obtained were observed with a microscope, it was confirmed that all the particles were present as single particles without any aggregation. The appearance was silver white, and no discoloration or uneven color was observed.
When this particle was observed in cross section, the film thickness of the outermost layer was 4 μm. Composition analysis of the cut cross section by X-ray microwave analysis confirmed that an Sn layer was present on the Ni underlayer, and Ag was dispersed in the Sn layer. When this plated coating was dissolved in a strong acid and the composition ratio was determined by atomic absorption analysis, it was Sn: Ag = 96.2: 3.8. Further, when the particles were subjected to thermal analysis by DSC, a melting peak was observed at 218 ° C., which is an alloy melting point of Sn / Ag / Cu.

(Example 6)
Substrate fine particles were polymerized in the same manner as in Example 3. Subsequently, particle | grain selection was performed with the sieve and the particle | grain of 310 micrometers was obtained. The particles were plated in the same manner as in Example 3.
When the plated particles thus obtained were observed with a microscope, it was confirmed that all the particles were present as single particles without any aggregation. The appearance was silver white, and no discoloration or uneven color was observed.
When this particle was observed in cross section, the film thickness of the outermost layer was 4 μm. Composition analysis of the cut cross section by X-ray microwave analysis confirmed that an Sn layer was present on the Ni underlayer, and Ag was dispersed in the Sn layer. When this plated coating was dissolved in a strong acid and the composition ratio was determined by atomic absorption analysis, it was Sn: Ag = 96.3: 3.7. Further, when the particles were subjected to thermal analysis by DSC, a melting peak was observed at 221 ° C., which is the Sn / Ag alloy melting point.

(Example 7)
Substrate fine particles were polymerized in the same manner as in Example 3. Subsequently, particle | grain selection was performed with the sieve and the particle | grain of 105 micrometers was obtained. The particles were plated in the same manner as in Example 3.
When the plated particles thus obtained were observed with a microscope, it was confirmed that all the particles were present as single particles without any aggregation. The appearance was silver white, and no discoloration or uneven color was observed.
When this particle was observed in cross section, the film thickness of the outermost layer was 4 μm. Composition analysis of the cut cross section by X-ray microwave analysis confirmed that an Sn layer was present on the Ni underlayer, and Ag was dispersed in the Sn layer. When this plated coating was dissolved in a strong acid and the composition ratio was determined by atomic absorption analysis, it was Sn: Ag = 96.3: 3.7. Further, when the particles were subjected to thermal analysis by DSC, a melting peak was observed at 221 ° C., which is the Sn / Ag alloy melting point.

(Example 8)
Substrate fine particles were polymerized in the same manner as in Example 3 to obtain 710 μm particles. The particles were electrolessly plated with nickel and copper as a conductive layer. Thereafter, a tin-silver plating treatment was performed in the same manner as in Example 3.
When the plated particles thus obtained were observed with a microscope, it was confirmed that all the particles were present as single particles without any aggregation. The appearance was silver white, and no discoloration or uneven color was observed.
When this particle was observed in cross section, the film thickness of the outermost layer was 4 μm. Composition analysis of the cut cross section by X-ray microwave analysis confirmed that an Sn layer was present on the Ni underlayer, and Ag was dispersed in the Sn layer. When this plated coating was dissolved in a strong acid and the composition ratio was determined by atomic absorption analysis, it was Sn: Ag = 96.2: 3.8. Further, when the particles were subjected to thermal analysis by DSC, a melting peak was observed at 218 ° C., which is an alloy melting point of Sn / Ag / Cu.

Example 9
Substrate fine particles were polymerized in the same manner as in Example 3 to obtain 710 μm particles. The particles were electrolessly plated with nickel as a conductive layer. The following were prepared as plating solutions. In 25 L of water, 537 g of tin sulfate (SnSO ₄ ), 1652 g of potassium pyrophosphate (K ₄ P ₂ O ₇ ), 25 g of polyethylene glycol (molecular weight: 6000), and 500 g of triethanolamine were uniformly dissolved. 42.5 g of silver nitrate (AgNO ₃ ) was added to this solution, and the solution was stirred for 2 hours. A tin-silver plating process was performed with the above plating solution under the same conditions as in Example 3.
When the plated particles thus obtained were observed with a microscope, it was confirmed that all the particles were present as single particles without any aggregation. The appearance was silver white, and no discoloration or uneven color was observed.
When this particle was observed in cross section, the film thickness of the outermost layer was 4 μm. Composition analysis of the cut cross section by X-ray microwave analysis confirmed that an Sn layer was present on the Ni underlayer, and Ag was dispersed in the Sn layer. When this plating film was dissolved in a strong acid and the composition ratio was determined by atomic absorption analysis, it was Sn: Ag = 90.2: 9.8. Further, when the particles were subjected to thermal analysis by DSC, a melting peak was observed at 221 ° C., which is the Sn / Ag alloy melting point.

(Comparative Example 3)
A nickel plating layer was formed as a conductive underlayer on a commercially available solder ball having a particle size of 800 μm.
Next, the following were prepared as plating solutions.
In water of the plating bath 20L, tin methanesulfonate ((CH ₃ SO ₃ ) 2 Sn) 0.2 mol / L, silver methanesulfonate (CH ₃ SO ₃ Ag) 0.008 mol / L, methanesulfonic acid (CH ₃ SO ₃ H) 2 mol / L, L-cysteine
0.04 mol / L, 2,2′-Dithiodianline 0.002 mol / L, and polyoxyethylene-α-naphthol 3 g / L were added.
The plating solution was put in a bathtub of a rotary plating apparatus, and 40 g of 710 μm particles plated with nickel were plated. The plating conditions were such that the bath temperature was 25 ° C., the current density was 0.5 A / dm ² , the peripheral speed was 18 Hz, and the rotation direction was reversed every 10 seconds.
When the plated particles thus obtained were observed with a microscope, it was confirmed that all the particles were present as single particles without any aggregation. The appearance was black, and uneven color was observed for each particle.
When this particle was observed in cross section, the film thickness of the outermost layer was 6 μm. Composition analysis of the cut cross section by X-ray microwave analysis confirmed that an Sn layer was present on the Ni underlayer, and Ag was dispersed in the Sn layer. This plating film was dissolved with a strong acid, and the composition ratio was determined by atomic absorption analysis. As a result, Sn: Ag = 64.0: 36.0 was obtained, and a composition having a remarkably high Ag content was obtained.

(Comparative Example 4)
A nickel plating layer was formed as a conductive underlayer on a commercially available solder ball having a particle size of 400 μm.
Using the same plating bath as in Example 3, tin-silver plating was performed using a conventional barrel. The plating conditions were a bath temperature of 50 ° C., a current density of 0.5 A / dm ² , and a barrel rotation speed of 3 rpm.
During the rotation of the barrel during plating, particle soaring was observed. When the obtained plated particles were observed with a microscope, the appearance showed white, but bare particles without plating were observed in about 10% of the particles.
When this particle was observed in cross section, the film thickness of the outermost layer was 4 μm. The composition of the cut cross section was analyzed by X-ray microwave analysis. As a result, an Sn layer was present on the Ni underlayer, and Ag was dispersed inside the Sn layer, but was present at the outer periphery. There wasn't. When this plating film was dissolved with a strong acid and the composition ratio was determined by atomic absorption analysis, it was Sn: Ag = 99.0: 1.0, and a composition with a remarkably low Ag content was obtained.

(Example 10)
A nickel plating layer was formed as a conductive underlayer on the substrate fine particles obtained by copolymerizing styrene and divinylbenzene to obtain particles having an average particle diameter of 710.5 μm and a standard deviation of 32.5 μm. The obtained fine particles were subjected to tin plating in the same manner as in Reference Example 1.
When the plated resin fine particles thus obtained were observed with a microscope, it was confirmed that there was no aggregation at all and all the particles were present as single particles. Moreover, as a result of observing and measuring 100 particles with a magnifying glass, the average particle size was 720 μm and the standard deviation was 18.1 μm.
The obtained particles were dispersed in a silver plating solution and stirred at 50 ° C. for 30 minutes to effect silver substitution plating. Composition analysis of the cut cross section of the particles by X-ray microwave analysis confirmed a three-layer structure of Ni, Sn, and Ag. When this plated coating was dissolved in a strong acid and the composition ratio was determined by atomic absorption analysis, it was Sn: Ag = 96.0: 4.0.
The particles were placed in a thermostatic bath, filled with nitrogen, heated to 200 ° C., and heat-treated for 12 hours. Composition analysis of the cross section of the heat-treated particles by X-ray microwave analysis confirmed that the Ag layer and Sn layer were diffused. Further, when the particles were subjected to thermal analysis by DSC, a melting peak was observed at 221 ° C., which is the Sn / Ag alloy melting point.

(Example 11)
Nickel plating was performed in the same manner as in Example 10, and then energized in a copper plating solution for 1 hour to perform copper plating with a barrel. Thereafter, tin plating was performed by barrel plating in the same manner as in Reference Example 1.
Composition analysis of the cut cross section of the particles by X-ray microwave analysis confirmed a three-layer structure of Ni, Cu, and Sn. When this plating film was dissolved in a strong acid and the composition ratio was determined, it was Sn: Cu = 99.0: 1.0.
The particles were placed in a thermostatic bath, filled with nitrogen, heated to 200 ° C., and heat-treated for 12 hours. Composition analysis of the cross section of the heat-treated particles by X-ray microwave analysis confirmed that the Cu layer and the Sn layer were diffused. When the particles were subjected to thermal analysis by DSC, a melting peak was observed at 227 ° C.

(Example 12)
The nickel, copper, and tin multilayered particles obtained in Example 11 were further subjected to silver displacement plating. Composition analysis of the cut cross section of the particles by X-ray microwave analysis confirmed a four-layer structure of Ni, Cu, Sn, and Ag. When this plating film was dissolved in a strong acid and the composition ratio was determined, it was Sn: Ag: Cu = 95.0: 4.0: 1.0.
The particles were placed in a thermostatic bath, filled with nitrogen, heated to 200 ° C., and heat-treated for 12 hours. Composition analysis of the cross section of the heat-treated particles by X-ray microwave analysis confirmed that the Cu layer, Ag layer, and Sn layer were diffused. Further, when the particles were subjected to thermal analysis by DSC, a melting peak was observed at 217 ° C.

(Example 13)
Nickel plating and tin plating were performed in the same manner as in Example 10. Then bismuth was plated with a barrel.
Composition analysis of the cut cross section of the particles by X-ray microwave analysis confirmed a three-layer structure of Ni, Sn, and Bi. When this plating film was dissolved in a strong acid and the composition ratio was determined, it was Sn: Bi = 40: 60.
The particles were placed in a thermostatic bath, filled with nitrogen, heated to 180 ° C., and heat-treated for 12 hours. Composition analysis of the cross section of the heat-treated particles by X-ray microwave analysis confirmed that the Bi layer and Sn layer were diffused. Further, when the particles were subjected to thermal analysis by DSC, a melting peak was observed at 139 ° C.

(Example 14)
Nickel plating, tin plating, and silver plating were performed in the same manner as in Example 10 except that the substrate fine particles obtained by copolymerizing divinylbenzene and tetramethylolmethane tetramethacrylate were used.
Composition analysis of the cut cross section of the particles by X-ray microwave analysis confirmed a three-layer structure of Ni, Sn, and Ag. When this plating film was dissolved in a strong acid and the composition ratio was determined, it was Sn: Ag = 96.0: 4.0.
The particles were placed in a thermostatic bath, filled with nitrogen, heated to 200 ° C., and heat-treated for 12 hours. Composition analysis of the cross section of the heat-treated particles by X-ray microwave analysis confirmed that the Ag layer and Sn layer were diffused. Further, when the particles were subjected to thermal analysis by DSC, a melting peak was observed at 221 ° C., which is an Sn / Ag alloy melting point.

(Example 15)
Nickel plating, tin plating, and silver plating were performed in the same manner as in Example 10 except that the substrate fine particles obtained by copolymerizing divinylbenzene and polytetramethylene glycol diacrylate were used.
Composition analysis of the cut cross section of the particles by X-ray microwave analysis confirmed a three-layer structure of Ni, Sn, and Ag. When this plating film was dissolved in a strong acid and the composition ratio was determined, it was Sn: Ag = 96.0: 4.0.
The particles were placed in a thermostatic bath, filled with nitrogen, heated to 200 ° C., and heat-treated for 12 hours. Composition analysis of the cross section of the heat-treated particles by X-ray microwave analysis confirmed that the Ag layer and Sn layer were diffused. Further, when the particles were subjected to thermal analysis by DSC, a melting peak was observed at 221 ° C., which is an Sn / Ag alloy melting point.

(Example 16)
Nickel plating, tin plating, and silver plating were performed in the same manner as in Example 10 using a copper ball having a particle diameter of 500 μm as a base material. Composition analysis of the cut cross section of the particles by X-ray microwave analysis confirmed a three-layer structure of Ni, Sn, and Ag. When this plating film was dissolved in a strong acid and the composition ratio was determined, it was Sn: Ag = 96.0: 4.0.
The particles were placed in a thermostatic bath, filled with nitrogen, heated to 200 ° C., and heat-treated for 12 hours. Composition analysis of the cross section of the heat-treated particles by X-ray microwave analysis confirmed that the Ag layer and Sn layer were diffused. Further, when this particle was subjected to thermal analysis by DSC, a melting peak was observed at 221 ° C., which is an alloy melting point of Sn / Ag.

(Example 17)
Nickel plating, tin plating, and silver plating were performed in the same manner as in Example 10 except that phenol resin base particles having a particle diameter of 400 μm were used.
Composition analysis of the cut cross section of the particles by X-ray microwave analysis confirmed a three-layer structure of Ni, Sn, and Ag. When this plating film was dissolved in a strong acid and the composition ratio was determined, it was Sn: Ag = 96.0: 4.0.
The particles were placed in a thermostatic bath, filled with nitrogen, heated to 200 ° C., and heat-treated for 12 hours. Composition analysis of the cross section of the heat-treated particles by X-ray microwave analysis confirmed that the Ag layer and Sn layer were diffused. Further, when the particles were subjected to thermal analysis by DSC, a melting peak was observed at 221 ° C., which is an Sn / Ag alloy melting point.

(Comparative Example 5)
Electroless nickel plating was performed on a commercially available solder ball having a particle size of 150 μm. The particles were plated with an alloy in a tin and silver bath. When the composition of the cut cross section of the obtained particles was analyzed by X-ray microwave analysis, an Sn / Ag alloy layer was confirmed. When this plating film was dissolved with a strong acid and the composition ratio was determined, it was Sn: Ag = 75: 25, and a composition having a remarkably high Ag content was obtained.

(Comparative Example 6)
Electroless nickel plating was performed on the same base particles as in Example 10. The particles were plated with an alloy in a bath of tin and copper. When the composition of the cut cross section of the obtained particles was analyzed by X-ray microwave analysis, an Sn / Cu alloy layer was confirmed. When this plating film was dissolved in a strong acid and the composition ratio was determined, it was Sn: Cu = 80: 20, and a composition having a remarkably high Cu content was obtained.

(Comparative Example 7)
When the nickel, tin, and silver particles produced in Example 10 were subjected to thermal analysis by DSC without heat treatment, a melting peak at 232 ° C., which is the melting point of tin alone, was observed.

(Example 18)
In a separable flask, 1.3 parts by weight of benzoyl peroxide as a polymerization initiator was uniformly mixed with 20 parts by weight of divinylbenzene, and this was mixed with 20 parts by weight of a 3% aqueous solution of polyvinyl alcohol and 0.5 parts by weight of sodium dodecyl sulfate. Was added and stirred well, and then 140 parts by weight of ion-exchanged water was added. The solution was reacted at 80 ° C. for 15 hours under a nitrogen stream while stirring. The obtained fine particles were washed with hot water and acetone and then subjected to particle selection with a sieve to obtain substrate fine particles having a center particle size of 300 μm. A nickel plating was formed thereon by electroless plating as a conductive underlayer. A nickel-plated dummy particle having a central particle size of 800 μm was synthesized in the same formulation.
Then, 40 g of 300 μm particles plated with nickel and 20 mL of 800 μm dummy particles were put into a rotary plating apparatus, and copper plating was performed. The plating conditions were such that 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 700 μm to separate 800 μm dummy particles and plating particles. When the plated particles thus obtained were observed in cross section, the film thickness of the copper layer was 3 μm. Further, when the obtained particles were further sieved with a sieve having an opening of 350 μm, the amount remaining on the sieve was 1% or less of the total weight, 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 number of particles having cracks and peeling was about 2% of the total.

(Example 19)
Polymerization was carried out in the same manner as in Example 18 using divinylbenzene and a tetrafunctional acrylic monomer on the substrate fine particles to obtain 300 μm particles. A nickel plating was formed thereon by electroless plating as a conductive underlayer. A nickel-plated dummy particle having a central particle size of 800 μm synthesized with divinylbenzene and a tetrafunctional acrylic monomer was obtained with the same formulation.
Then, 40 g of 300 μm particles plated with nickel and 20 mL of 800 μm dummy particles were put into a rotary plating apparatus, and copper plating was performed. The plating conditions were such that 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 700 μm to separate 800 μm dummy particles and plating particles. When the plated particles thus obtained were observed in cross section, the film thickness of the copper layer was 3 μm. Further, when the obtained particles were further sieved with a sieve having an opening of 350 μm, the amount remaining on the sieve was 1% or less of the total weight, 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 number of particles having cracks and peeling was about 2% of the total.

(Example 20)
In the same manner as in Example 18, 300 μm particles were obtained. A nickel plating was formed thereon by electroless plating as a conductive underlayer. A nickel-plated dummy particle having a center particle diameter of 2000 μm was synthesized in the same formulation.
Next, 40 g of 300 μm particles plated with nickel and 30 mL of 2000 μm dummy particles were put into a rotary plating apparatus, and copper plating was performed. The plating conditions were such that 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 1500 μm to separate 2000 μm dummy particles and plating particles. When the plated particles thus obtained were observed in cross section, the film thickness of the copper layer was 3 μm. The obtained particles were further sieved with a sieve having an opening of 350 μm. As a result, 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 number of particles having cracks and peeling was about 2% of the total.

(Example 21)
In the same manner as in Example 18, 300 μm particles were obtained. A nickel plating was formed thereon by electroless plating as a conductive underlayer. A nickel-plated dummy particle having a central particle diameter of 500 μm was synthesized in the same formulation.
Next, 40 g of 300 μm particles plated with nickel and 20 mL of 500 μm dummy particles were put into a rotary plating apparatus, and copper plating was performed. The plating conditions were such that 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 a mesh size of 450 μm to separate 500 μm dummy particles and plating particles. When the plated particles thus obtained were observed in cross section, the film thickness of the copper layer was 3 μm. Further, when the obtained particles were further sieved with a sieve having an opening of 350 μm, the amount remaining on the sieve was 1% or less of the total weight, 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 number of particles having cracks and peeling was about 2% of the total.

(Example 22)
In the same manner as in Example 18, 500 μm particles were obtained. A nickel plating was formed thereon by electroless plating as a conductive underlayer. A nickel-plated dummy particle having a central particle size of 800 μm was synthesized in the same formulation.
Next, 40 g of 500 μm particles plated with nickel and 20 mL of 800 μm dummy particles were put into a rotary plating apparatus, and copper plating was performed. The plating conditions were such that 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 700 μm to separate 800 μm dummy particles and plating particles. When the cross section of the plated particles thus obtained was observed, the thickness of the copper layer was 2 μm. Further, when the obtained particles were further sieved with a sieve having an opening of 450 μm, the amount remaining on the sieve was about 1% of the total weight, 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 number of particles having cracks and peeling was about 2% of the total.

(Example 23)
In the same manner as in Example 18, 100 μm particles were obtained. A nickel plating was formed thereon by electroless plating as a conductive layer base. A nickel-plated dummy particle having a central particle diameter of 500 μm was synthesized in the same formulation.
Then, 40 g of 100 μm particles plated with nickel and 20 mL of 500 μm dummy particles were put into a rotary plating apparatus, and copper plating was performed. The plating conditions were such that 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 a mesh size of 450 μm to separate 500 μm dummy particles and plating particles. When the cross section of the plated particles thus obtained was observed, the thickness of the copper layer was 2 μm. Further, when the obtained particles were further sieved with a sieve having an opening of 150 μm, the amount remaining on the sieve was about 1% of the total weight, and no large aggregation was observed. When 2,000 of these particles were observed with a microscope, the appearance showed a lustrous copper color, and the number of particles with cracks or peeling was about 1% of the total.

(Example 24)
In the same manner as in Example 23, 100 μm particles were obtained. A nickel plating was formed thereon by electroless plating as a conductive underlayer. A nickel-plated dummy particle having a center particle diameter of 2000 μm was synthesized in the same formulation.
Next, 40 g of 100 μm particles plated with nickel and 30 mL of 2000 μm dummy particles were put into a rotary plating apparatus, and copper plating was performed. The plating conditions were such that 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 1500 μm to separate 2000 μm dummy particles and plating particles. When the cross section of the plated particles thus obtained was observed, the thickness of the copper layer was 2 μm. Further, when the obtained particles were further sieved with a sieve having an opening of 150 μm, only 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 showed a lustrous copper color, and the number of particles with cracks or peeling was about 1% of the total.

(Example 25)
In the same manner as in Example 18, 50 μm particles were obtained. A nickel plating was formed thereon by electroless plating as a conductive underlayer. A nickel-plated dummy particle having a central particle diameter of 500 μm was synthesized in the same formulation.
Next, 40 g of 50 μm particles plated with nickel and 30 mL of 500 μm dummy particles were put into a rotary plating apparatus, and copper plating was performed. The plating conditions were such that 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 a mesh size of 450 μm to separate 500 μm dummy particles and plating particles. When the cross section of the plated particles thus obtained was observed, the thickness of the copper layer was 2 μm. Further, when the obtained particles were further sieved with a sieve having an opening of 100 μm, the amount remaining on the sieve was about 4% of the total weight, and no large aggregation was observed. When 2,000 of these particles were observed with a microscope, the appearance showed a lustrous copper color, and the number of particles with cracks or peeling was about 1% of the total.

(Example 26)
40 g of 304 μm copper-plated particles obtained in Example 18 and 20 mL of 800 μm nickel-plated dummy particles obtained in Example 18 were added, and eutectic solder plating was performed. The plating conditions were such that 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 20 seconds.
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 plated particles thus obtained was observed, the film thickness of the eutectic solder layer was 6 μm. Further, when the obtained particles were further sieved with a sieve having an opening of 350 μm, only 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 showed a glossy copper color, and the number of particles having cracks and peeling was about 2% of the total.

(Comparative Example 8)
In the same manner as in Example 18, 300 μm particles were obtained. A nickel plating was formed thereon by electroless plating as a conductive underlayer. Next, only 40 g of 300 μm dummy particles plated with nickel were put into a rotary plating apparatus, and copper plating was performed. The plating conditions were such that 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.
When the plated particles thus obtained were observed in cross section, the film thickness of the copper layer was 3 μm. Further, when the obtained particles were further sieved with a sieve having an opening of 350 μm, what was left on the sieve was about 10% of the total weight, and a large aggregation of about 2 mm square was recognized. When 2,000 of these particles were observed with a microscope, the appearance showed a lustrous copper color, and the number of particles with cracks or peeling was about 1% of the total.

(Comparative Example 9)
In the same manner as in Example 23, 100 μm particles were obtained. A nickel plating was formed thereon by electroless plating as a conductive underlayer. Subsequently, only 40 g of 100 μm particles plated with nickel were put into a rotary plating apparatus, and copper plating was performed. The plating conditions were such that 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.
When the cross section of the plated particles thus obtained was observed, the thickness of the copper layer was 2 μm. Further, when the obtained particles were further sieved with a sieve having an opening of 350 μm, what was left on the sieve was about 20% of the total weight, and large aggregation of about 5 mm square was recognized. When 2,000 of these particles were observed with a microscope, the appearance showed a lustrous copper color, and the number of particles with cracks or peeling was about 1% of the total.

(Comparative Example 10)
In the same manner as in Example 18, 300 μm particles were obtained. A nickel plating was formed thereon by electroless plating as a conductive underlayer. Next, 40 g of 100 μm particles plated with nickel and 20 mL of zirconia ball dummy particles having a particle diameter of 1000 μm were put into a rotary plating apparatus, and copper plating was performed. The plating conditions were such that 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 900 μm to separate 1000 μm dummy particles and plating particles. When the plated particles thus obtained were observed in cross section, the film thickness of the copper layer was 3 μm. Further, when the obtained particles were further sieved with a sieve having an opening of 350 μm, only 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 matte copper color, and the number of particles with cracks or peeling was about 40% of the total.

(Comparative Example 11)
In the same manner as in Example 18, 300 μm particles were obtained. A nickel plating was formed thereon by electroless plating as a conductive underlayer. Next, 40 g of 300 μm particles plated with nickel and 20 mL of stainless ball dummy particles having a particle diameter of 1000 μm were put into a rotary plating apparatus, and copper plating was performed. The plating conditions were such that 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 900 μm to separate 1000 μm dummy particles and plating particles. When the plated particles thus obtained were observed in cross section, the film thickness of the copper layer was 3 μm. Further, when the obtained particles were further sieved with a sieve having an opening of 350 μm, only 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 matte copper color, and the number of particles with cracks or peeling was about 40% of the total.

Since the present invention has the above-described configuration, it is possible to provide means for bonding between substrates or between a substrate and a chip that can maintain conduction between substrates for a long time even under severe thermal cycle conditions.

It is the schematic which shows an example of the plating apparatus used for this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cover 2 Electrode 2a Anode 3 Rotating shaft 4 Processing chamber 5 Container 6 Plating solution supply pipe 7 Plating solution discharge pipe 8 Opening 11 Bottom plate 12 Contact ring 13 Porous ring

Claims (39)

Conductive fine particles in which the surface of substrate fine particles made of resin is covered with one or more metal layers,
The thermal decomposition temperature of the resin is 300 ° C. or higher, and
Conductive fine particles, wherein at least one of the metals constituting the metal layer is an alloy and / or metal having a melting point of 150 to 300 ° C. Conductive fine particles in which the surface of substrate fine particles made of resin is covered with one or more metal layers,
The thermal expansion coefficients of all the metal layers are 1 × 10 ^{−5 to} 3 × 10 ⁻⁵ (1 / K), and
Conductive fine particles, wherein the ratio of the thermal expansion coefficient between each metal layer and the substrate fine particles (thermal expansion coefficient of the substrate fine particles / thermal expansion coefficient of the metal layer) is 0.1 to 10, respectively. The metal layer is at least one selected from the group consisting of gold, silver, copper, platinum, zinc, iron, lead, tin, aluminum, cobalt, indium, nickel, chromium, antimony, bismuth, germanium, cadmium, and silicon. The conductive fine particles according to claim 1, wherein the conductive fine particles are made of the following metals. The conductive fine particles according to claim 1, 2, or 3, wherein the outer diameter is 200 to 1000 µm, and the thickness of the metal layer is 0.5 to 30% of the radius of the base fine particles. 4. The outer diameter is 200 to 1000 [mu] m, and the thickness of the metal layer has a relationship represented by the following formula (1) with respect to the radius of the substrate fine particles. Conductive fine particles.
Y = (− 25 / 100,000 · X + c) × 100 (1)
In the formula, Y represents the ratio (%) of the thickness of the metal layer to the radius of the substrate fine particles, X represents the outer diameter (μm) of the conductive fine particles, and c represents a constant of 0.10 to 0.35. . However, Y> 0. 4. The conductive fine particle according to claim 1, wherein the outer diameter is 50 to 200 [mu] m and the thickness of the metal layer is 1 to 100% of the radius of the base fine particle. The conductive fine particles according to claim 1, 2 or 3, wherein the outer diameter is 50 to 200 µm, and the thickness of the metal layer is 4 to 40% of the radius of the base fine particles. The conductive fine particles according to claim 1, 2, 3, 4, 5, 6 or 7, wherein the number of particles having bubbles in the substrate fine particles is 1% or less of the total number. The outer diameter of the substrate fine particles is 50 to 1000 μm, and particles having bubbles having a diameter of 1% or more of the radius of the substrate fine particles are 1% or less of the total number, Conductive fine particles according to 2 or 3. The total amount of substances having a boiling point of 300 ° C or less contained in the substrate fine particles is 1% by weight or less of the total weight of the particles, wherein the total weight of the particles is 1, 2, 3, 4, 5, 6, 7, Conductive fine particles according to 8 or 9. 11. The total amount of moisture contained in the substrate fine particles is 1% by weight or less based on the total weight of the particles, 11. 1, 3, 4, 5, 6, 7, 8, 9 or 10 Conductive fine particles. The conductive fine particles according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11, wherein the sphericity is 1.5% or less. The conductive fine particles according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11 having a resistance value of 100 mΩ or less. The ratio of the maximum value and the minimum value of E ′ in the temperature range of −60 to 200 ° C. of the substrate fine particles is 1 to 2, wherein the ratio is 1-2. , 8, 9, 10 or 11. The K value of the substrate fine particles is 1000 to 10,000 (MPa), characterized in that it is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14. The electroconductive fine particles as described. The outer diameter of the substrate fine particles is 700 to 800 µm, the metal layer is composed of 2 to 4 layers, and the outermost layer is a solder alloy and / or tin. The electroconductive fine particles according to 4, 5, 8, 9, 10, 11, 12, 13, 14 or 15. The outer diameter of the substrate fine particles is 700 to 800 μm, the metal layer is composed of four layers, the innermost layer is a nickel layer of 0.1 to 0.5 μm, the outer layer is a copper layer of 2 to 12 μm, and the outer layer is 2 to 2 30 μm lead is 82 to 98%, tin is 2 to 18% solder alloy layer, outermost layer is 2 to 30 μm lead is 25 to 50%, tin is 50 to 75% solder alloy layer The conductive fine particles according to claim 1, 2, 3, 4, 5, 8, 9, 10, 11, 12, 13, 14, 15 or 16. The outer diameter of the substrate fine particles is 250 to 400 µm, the metal layer is composed of 2 to 4 layers, and the outermost layer is a solder alloy and / or tin. The conductive fine particles according to 3, 4, 5, 8, 9, 10, 11, 12, 13, 14 or 15. The outer diameter of the substrate fine particles is 50 to 150 µm, the metal layer is composed of 2 to 4 layers, and the outermost layer is a solder alloy and / or tin. The conductive fine particles according to 3, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15. Conductivity according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 or 19 between two or more substrates A substrate structure connected by fine particles,
A substrate structure having a CV value of a diameter of a substrate fine particle of 1.5% or less. Conductivity according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 or 19 between two or more substrates A substrate structure connected by fine particles,
A substrate structure, wherein the particle diameter of the substrate fine particles is ± 5% of the center value. Conductivity according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 or 19 between two or more substrates A substrate structure connected by fine particles,
The distance between the said board | substrates is 95 to 120% of the particle size of base material microparticles | fine-particles, The board | substrate structure body characterized by the above-mentioned. Conductivity according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 or 19 between two or more substrates A substrate structure connected by fine particles,
2. A substrate structure having different materials and / or compositions constituting two or more substrates. 24. The substrate structure according to claim 23, wherein a difference in linear expansion coefficient between the substrates is 10 ppm or more. A method of plating fine particles that covers the surface of a fine particle of a substrate with at least two metal alloy layers,
The metal alloy layer is formed by depositing at least one type of metal by electroplating, and at least another type of metal incorporating a dispersed metal in the plating bath. A method for plating fine particles. 26. The fine particles according to claim 25, wherein at least one of the metals deposited by electroplating of the metal alloy layer is tin, and at least one of the metals incorporated in a dispersed state in the plating bath is silver. Plating method. The metal alloy layer is plated with an alloy electroplating bath characterized by containing at least a divalent tin compound, a monovalent silver compound, and a eutectoid stabilizing aid as a basic composition. The method for plating fine particles according to claim 26. 28. The fine particles according to claim 27, wherein the fine particles are plated using a rotary plating apparatus having a cathode on the outer peripheral portion, holding the plating solution and the fine particles of the plating base in the main body, and repeatedly energizing and stirring while rotating. Plating method. Conductive fine particles plated by the fine particle plating method according to claim 25, 26, 27 or 28. A conductive connection structure, wherein the conductive connection structure is connected by the conductive fine particles according to claim 29. Conductive fine particles in which the surface of the substrate fine particles is covered with one or more metal layers,
Conductive fine particles, wherein at least one of the metal layers is an alloy layer obtained by thermally diffusing two or more metal layers. The alloy layer is at least two metal layers made of a metal selected from the group consisting of tin, silver, copper, zinc, bismuth, indium, aluminum, cobalt, nickel, chromium, titanium, antimony, germanium, cadmium, and silicon. The conductive fine particles according to claim 31, wherein the conductive fine particles are obtained by thermal diffusion. The conductive fine particles according to claim 32, wherein the base fine particles are made of a resin. 34. A conductive joint structure connected by the conductive fine particles according to claim 33. A method for plating fine particles,
A rotatable dome having a cathode on the outer peripheral portion and having a filter portion for allowing the plating solution to pass through and discharging, and an anode installed in the dome so as not to contact the cathode, and rotating the dome Using a rotary plating device that repeats energization and stirring while bringing the fine particles into contact with the cathode by centrifugal force due to
Fine particles characterized in that plating is performed by simultaneously adding dummy particles having a hardness equivalent to that of the substrate fine particles to be plated and whose particle size is 1.5 to 30 times that of the substrate fine particles to be plated. Plating method. 36. The method for plating fine particles according to claim 35, wherein the substrate fine particles to be plated are resin, and the particle size thereof is 1 to 500 [mu] m. The fine particle plating method according to claim 36, wherein the dummy particles are made of a resin. A conductive fine particle plated by the fine particle plating method according to claim 35, 36 or 37. A conductive connection structure, wherein the conductive connection structure is connected by the conductive fine particles according to claim 38.

Images