JP5108456B2 - Conductive fine particles - Google Patents

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 reducing a force applied in the circuit.

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 conductive fine particles having an ability to relieve a force applied to a circuit such as a substrate.

Reference invention 1 is conductive fine particles in which the surface of substrate fine particles made of a 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. The conductive fine particles are (1 / K).
The present 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, the thermal decomposition temperature of the resin is 300 ° C. or higher, and the metal layer is The ratio between the maximum value and the minimum value of the storage elastic modulus E ′ in the temperature range of −60 to 200 ° C. of the base particle is at least one of the constituent metals is an alloy and / or metal having a melting point of 150 to 300 ° C. Is a conductive fine particle having 1 to 2.
Reference invention 2 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 thermal expansion coefficient of all the layers of the metal layer is 1 × 10 ^−5. And 3 × 10 ⁻⁵ (1 / K), and the ratio of the thermal expansion coefficient between each metal layer and the above-mentioned substrate fine particles (thermal expansion coefficient of the substrate fine particles / thermal expansion coefficient of the metal layer) is 0, respectively. .1 to 10 conductive fine particles.
Reference invention 3 is a method of plating fine particles in which the surface of the substrate fine particles 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, This is a fine particle plating method formed by incorporating a metal in a dispersed state into at least another kind of metal in a plating bath.
Reference invention 4 is a conductive fine particle in which the surface of a substrate fine particle is covered with one or more metal layers, and at least one of the metal layers heats two or more metal layers. It is the electroconductive fine particle which is an alloy layer obtained by making it diffuse.
Reference invention 5 is a method of plating fine particles, which has a cathode on the outer periphery, a rotatable dome having a filter part for allowing the plating solution to pass through and discharging, and the cathode is not in contact with the cathode. A rotating type 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 has the same hardness as the base fine particles to be plated. And a method of plating fine particles in which plating is performed by simultaneously adding dummy particles whose particle size is 1.5 to 30 times that of the fine particles of the substrate to be plated.
The present invention is described in detail below.

Reference invention 1, the present invention, and reference invention 2 are conductive fine particles in which the surface of substrate fine particles made of resin is covered with one or more metal layers.

The resin used in Reference Invention 1 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 Reference Invention 1, 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 present 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 Reference Invention 1, the present invention and Reference Invention 2 is not particularly limited as long as it satisfies the above conditions. For example, phenol resin, amino resin, acrylic resin, polyester resin, urea resin, melamine Examples thereof include crosslinked or non-crosslinked synthetic resins such as resins, alkyd resins, polyimide resins, urethane resins, and epoxy 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 Reference Invention 1, Present Invention and Reference Invention 2 is not particularly limited, and examples thereof include gold, silver, copper, platinum, zinc, iron, lead, tin, aluminum, cobalt, indium, nickel, chromium, antimony, Examples thereof include those made of at least one metal selected from the group consisting of 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 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 Reference Invention 2, the thermal expansion coefficients of all the metal layers are 1 × 10 ^{−5 to} 3 × 10 ⁻⁵ (1 / K), respectively, and the thermal expansion coefficient between each metal layer and the base particle The ratio (thermal expansion coefficient of the substrate fine particles / thermal expansion coefficient of the metal layer) is 0.1 to 10 respectively. Since the conductive fine particles of Reference Invention 2 satisfy the above-described conditions, the metal layer is not destroyed by the expansion / contraction of the substrate fine particles even when the temperature changes, and the substrate fine particles and the metal layer are peeled off. Connection stability can be ensured.

When the conductive fine particles of Reference Invention 1, Invention and Reference Invention 2 have an outer diameter of 200 to 1000 μm, the thickness of the metal layer is preferably 0.5 to 30% of the radius of the substrate fine particles. 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.

In the conductive fine particles of Reference Invention 1, Invention and Reference Invention 2, when the outer diameter is 50 to 200 μm, the thickness of the metal layer is preferably 1 to 100% of the radius of the substrate fine particles. 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 Reference Invention 1, Invention and Reference Invention 2, it is preferable that the number of particles having bubbles in the substrate fine particles is 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 Reference Invention 1, Invention and Reference Invention 2 is 50 to 1000 μm, the entire particles with bubbles having a diameter of 1% or more of the radius of the base fine particles It is preferably 1% or less of the 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, the fine particles expand during heating such as reflow and cause micro cracks in the solder. For this reason, the conductive fine particles of Reference Invention 1, Present Invention and Reference Invention 2 have a total amount of substances having a boiling point of 300 ° C. or less such as water contained in the substrate fine particles of 1% by weight or less of the total weight of the particles. Preferably there is. If it exceeds 1% by weight, the defect rate cannot be ignored, which is not preferable.

The conductive fine particles of Reference Invention 1, Invention, and Reference Invention 2 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 Reference Invention 1, Invention and Reference Invention 2 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 Reference Invention 1, Invention and Reference Invention 2, the ratio of the maximum value and the minimum value of the storage elastic modulus E ′ in the temperature range of −60 to 200 ° C. of the substrate fine particles is 1-2. Is preferred. 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 Reference Invention 1, Invention, and Reference Invention 2, 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 Reference Invention 1, Invention and Reference Invention 2, 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.

Two or more substrates are connected by the conductive fine particles of Reference Invention 1, the present invention or Reference Invention 2 to form a substrate structure.

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.

Reference invention 3 is a method for plating fine particles in which the surface of the substrate fine particles is covered with at least two metal alloy layers.
The metal alloy layer in Reference Invention 3 is formed by depositing at least one type of metal by electroplating, and at least another type of metal incorporating a metal in a dispersed state in the plating bath. It is characterized by being.

The conductive fine particles obtained by Reference Invention 3 are obtained by covering the surface of the base fine particles made of resin and metal balls 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 Reference Invention 3, for example, by using a plating bath containing, as a basic composition, a divalent tin compound, a monovalent silver compound, and a eutectoid stabilizing aid, tin of the alloy composition is electroplated as ions, and silver is added. It is possible to deposit in the plating film as metallic silver 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 Reference Invention 3, any known non-cyanide compounds can be used. For example, tin sulfate, tin chloride, tin bromide, tin oxide, tin borofluoride, tin silicofluoride Organic acid salts and inorganic acid salts such as tin sulfamate, tin oxalate, tin tartrate, tin gluconate, tin pyrophosphate, tin methanesulfonate and tin alkanol sulfonate 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 stabilizing aid used in Reference Invention 3 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 Reference Invention 3, any known non-cyanide compounds can be used. For example, silver oxide, silver nitrate, silver sulfate, silver chloride, silver sulfamate, silver citrate, 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 salt thereof having an action of increasing the eutectoid amount of silver in an acidic plating bath may be added to the plating bath of Reference Invention 3. . 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.

Further, as a surface conditioner for imparting gloss to the surface of the tin-silver alloy film obtained by electrolysis from the plating bath of Reference Invention 3, for example, polyethylene glycol, polyoxyethylene alkyl phenyl ether, polyoxyethylene 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 Reference Invention 3 is not particularly limited, but for particles of 500 μm or less, the outer peripheral part has a cathode, the plating solution and the plating substrate fine particles are held inside the main body, and energized and stirred while rotating. From the viewpoint of uniformity and agglomeration, it is preferable to perform plating using a rotary plating apparatus that repeats the above (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.

When the conductive fine particles plated by the fine particle plating method of Reference Invention 3 are used when connecting the electrodes, the force applied in the circuit can be alleviated and the conductive connection structure is excellent.

Reference invention 4 is a conductive fine particle in which the surface of the base particle is covered with one or more metal layers. Reference invention 4 is characterized in that 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 Reference Invention 4 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 Reference Invention 4 are used as BGA solder balls, anisotropic conductive sheets, and anisotropic conductive adhesives for connecting ICs, LSIs and the like on a substrate, and are 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.

Reference invention 5 is a method of plating fine particles, which has a cathode on the outer periphery, a rotatable dome having a filter part for allowing the plating solution to pass through and discharging, and the cathode is not in contact with the cathode. A rotating type 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 has the same hardness as the base fine particles to be plated. In addition, plating is performed by simultaneously adding dummy particles having a particle size of 1.5 to 30 times that of the substrate fine particles to be plated.

The conductive fine particles obtained in Reference Invention 5 are obtained by covering the surface of base material fine particles made of resin and metal balls 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 Reference Invention 5 are 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 Reference Invention 5 includes a rotatable dome having a filter portion that allows the 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 is used in which the fine particles are brought into contact with the cathode by the effect of centrifugal force caused by the rotation of the dome, and the energization and stirring are repeated. This is the same as that used in Reference Invention 3.

In Reference Invention 5, at this time, plating is performed by simultaneously adding dummy particles that have the same hardness as 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. .

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.

Fine particles plated by the fine particle plating method of Reference Invention 5 can be used as conductive fine particles used for connecting electrodes. The conductive fine particles can improve the connection reliability by reducing the force applied in the circuit.

ADVANTAGE OF THE INVENTION According to this invention, the electroconductive fine particles which have the capability to relieve | moderate the force concerning circuits, such as a board | substrate, can be provided.

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 2)
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 3)
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 4)
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 5-7)
A material similar to that of Reference Example 3 was prepared except that the average particle diameter of the base material fine particles of Reference Example 3 was 398.2 μm and the standard deviation was 5.8 μm. This was designated as Reference Example 5 .
Similarly, the same material as in Reference Example 3 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 6 .
The metal layer of Reference Example 3 is Ni plating for the innermost layer, Cu plating for the outer layer, plating of a solder alloy (high temperature solder) whose outer layer is lead 9: tin 1, and 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 7 .

(Reference Examples 8 to 10)
A material similar to that of Reference Example 4 was prepared, except that the average particle size of the substrate fine particles of Reference Example 4 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 4 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 4, 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 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 .

(Reference Example 11)
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.

(Reference Example 12)
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 1
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 size 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 the storage elastic modulus 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 1)
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 the storage elastic modulus 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, Examples and Comparative Examples were placed on a dummy chip, and these were bonded to a printed 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.

(Reference Example 13)
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.

(Reference Example 14)
Polymerization was performed in the same manner as in Reference Example 13 using divinylbenzene and a tetrafunctional acrylic monomer as the base material fine particles to obtain 710 μm particles. Thereafter, plating was performed in the same manner as in Reference Example 13 .
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.

(Reference Example 15)
In place of the resin particles, tin-silver plating treatment was performed in the same manner as in Reference Example 13 using a rotary plating apparatus using copper balls having a particle diameter of 500 μm as base particles.
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.

(Reference Example 16)
Substrate fine particles were polymerized in the same manner as in Reference Example 13 . 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 Reference Example 13 .
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.

(Reference Example 17)
Substrate fine particles were polymerized in the same manner as in Reference Example 13 . 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 Reference Example 13 .
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.

(Reference Example 18)
Substrate fine particles were polymerized in the same manner as in Reference Example 13 to obtain particles of 710 μm. 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 Reference Example 13 .
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.

(Reference Example 19)
Substrate fine particles were polymerized in the same manner as in Reference Example 13 to obtain particles of 710 μm. 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 treatment was performed with the above plating solution under the same conditions as in Reference Example 13 .
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.

(Reference Example 20)
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.

(Reference Example 21)
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 Reference Example 13 , 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.

(Reference Example 22)
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.

(Reference Example 23)
Nickel plating was performed in the same manner as in Reference Example 22, 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.

(Reference Example 24)
Silver substitution plating was further performed on the particles obtained by multilayer plating of nickel, copper, and tin obtained in Reference Example 23 . 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.

(Reference Example 25)
Nickel plating and tin plating were performed in the same manner as in Reference Example 22 . 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.

(Reference Example 26)
Nickel plating, tin plating, and silver plating were performed in the same manner as in Reference Example 22 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.

(Reference Example 27)
Nickel plating, tin plating, and silver plating were performed in the same manner as in Reference Example 22 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.

(Reference Example 28)
Nickel plating, tin plating, and silver plating were performed in the same manner as in Reference Example 22 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.

(Reference Example 29)
Nickel plating, tin plating, and silver plating were performed in the same manner as in Reference Example 22 except that phenol resin substrate fine 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.

(Reference Example 30)
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.

(Reference Example 31)
Electroless nickel plating was performed on the same base particles as in Reference Example 22 . 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.

(Reference Example 32)
When the nickel, tin, and silver particles produced in Reference Example 22 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.

(Reference Example 33)
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.

(Reference Example 34)
Polymerization was performed on the substrate fine particles in the same manner as in Reference Example 33 using divinylbenzene and a tetrafunctional acrylic monomer 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.

(Reference Example 35)
In the same manner as in Reference Example 33 , 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.

(Reference Example 36)
In the same manner as in Reference Example 33 , 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.

(Reference Example 37)
In the same manner as in Reference Example 33 , 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.

(Reference Example 38)
In the same manner as in Reference Example 33 , 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.

(Reference Example 39)
In the same manner as in Reference Example 38 , 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.

(Reference Example 40)
In the same manner as in Reference Example 33 , 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.

(Reference Example 41)
And particles 40g that copper plating 304μm obtained in Reference Example 33, similarly charged with dummy particles 20mL nickel-plated 800μm obtained in Reference Example 33 was subjected to eutectic solder plating. 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.

(Reference Example 42)
In the same manner as in Reference Example 33 , 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.

(Reference Example 43)
In the same manner as in Reference Example 38 , 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.

(Reference Example 44)
In the same manner as in Reference Example 33 , 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.

(Reference Example 45)
In the same manner as in Reference Example 33 , 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.

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 (1)

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
Ri at least one alloy and / or metal der melting point 150 to 300 ° C. Of the metal constituting the metal layer,
The conductive fine particle, wherein the ratio of the maximum value and the minimum value of the storage elastic modulus E 'in the temperature range of -60 to 200C of the base particle is 1-2 .

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