WO2021182617A1

WO2021182617A1 - Conductive particles, conductive material and connection structure

Info

Publication number: WO2021182617A1
Application number: PCT/JP2021/010105
Authority: WO
Inventors: 寛人松浦; 脇屋　武司
Original assignee: 積水化学工業株式会社
Priority date: 2020-03-13
Filing date: 2021-03-12
Publication date: 2021-09-16
Also published as: JPWO2021182617A1; TW202141658A

Abstract

The present invention provides conductive particles which are capable, in cases where electrodes are electrically connected thereby, of: (1) effectively lowering the connection resistance between electrodes arranged in the vertical direction and to be connected to each other; (2) enhancing the insulation reliability between electrodes arranged in the horizontal direction and not to be connected to each other; and (3) enhancing the current resistance characteristics.　Each of the conductive particles according to the present invention comprises a metal particle having a porous structure, while being configured such that the conductive particle has a specific surface area of 10 m²/g or more (configuration A) or such that the conductive particle has a specific surface area of less than 10 m²/g and a specific gravity of from 1 g/cm³ to 8 g/cm³ (configuration B).

Description

Conductive particles, conductive materials and connecting structures

The present invention relates to conductive particles that can be used for electrical connection between electrodes and the like. The present invention also relates to a conductive material and a connecting structure using the above conductive particles.

Anisotropic conductive materials such as anisotropic conductive paste and anisotropic conductive film are widely known. In the anisotropic conductive material, conductive particles are dispersed in the binder resin. Further, as the conductive particles, conductive particles in which base particles such as resin particles or metal particles are coated with a conductive portion are widely used (for example, Patent Documents 1 and 2).

The anisotropic conductive material is used to obtain various connection structures. Connections using the anisotropic conductive material include a connection between a flexible printed circuit board and a glass substrate (FOG (Film on Glass)), a connection between a semiconductor chip and a flexible printed circuit board (COF (Chip on Film)), and a semiconductor chip. The connection between the glass substrate and the glass substrate (COG (Chip on Glass)), the connection between the flexible printed circuit board and the glass epoxy substrate (FOB (Film on Board)), and the like can be mentioned.

Japanese Unexamined Patent Publication No. 2012-06925 JP-A-11-152598

In recent years, due to changes in materials used for wiring in printed wiring boards and the like, and changes in mounting methods, when connecting electrodes using conductive particles to produce a connection structure, the electrodes are connected in the vertical direction. It is desired to further reduce the connection resistance of the.

In the conventional conductive particles in which the resin particles as the base particles are coated with the conductive portion (plating layer), the connection resistance between the electrodes may increase due to the occurrence of plating peeling or the like.

On the other hand, in the conventional conductive particles in which the conductive portion is coated on the metal particles as the base material particles, the connection resistance between the electrodes can be lowered to some extent. However, when metal particles are used as the base particles, it is difficult to reduce the coefficient of variation (CV value) of the particle size of the conductive particles. When the coefficient of variation of the particle size of the conductive particles is large, a short circuit may occur between the electrodes in the lateral direction which should not be connected, and in particular, a short circuit is likely to occur between the electrodes having a fine pitch.

Also, with conventional conductive particles, as the applied current increases, the voltage also increases accordingly. Conventional connection structures using conductive particles may have low withstand current characteristics, and the voltage may rise sharply when a current is applied.

An object of the present invention is that when the electrodes are electrically connected, 1) the connection resistance between the electrodes in the vertical direction to be connected can be effectively reduced, and 2) the connection resistance in the horizontal direction which should not be connected can be effectively reduced. It is an object of the present invention to provide conductive particles capable of enhancing the insulation reliability between the electrodes of the above and 3) enhancing the current-bearing characteristics. Another object of the present invention is to provide a conductive material and a connecting structure using the above conductive particles.

According to a broad aspect of the present invention, conductive particles comprising metal particles having a porous structure and having the following constitution A or the following constitution B are provided.

Configuration A: The specific surface area of the conductive particles is 10 m ² / g or more.

Configuration B: The specific surface area of the conductive particles ^{is less than 10 m 2} / g, and the specific gravity is 1 g / cm ³ or more and 8 g / cm ³ or less.

In a specific aspect of the conductive particles according to the present invention, the conductive particles include the configuration A.

In a specific aspect of the conductive particles according to the present invention, the conductive particles include the configuration B.

In a specific aspect of the conductive particles according to the present invention, the conductive particles include a conductive portion arranged on the outer surface of the metal particles.

In a specific aspect of the conductive particles according to the present invention, the thickness of the conductive portion is less than 50 nm when the configuration A is provided, and the thickness of the conductive portion is 50 nm when the configuration B is provided. That is all.

In certain aspects of the conductive particles according to the present invention, the conductive particles further include an insulating substance disposed on the outer surface of the conductive portion.

In a specific aspect of the conductive particles according to the present invention, the conductive particles have protrusions on the outer surface of the conductive portion.

In a specific aspect of the conductive particles according to the present invention, the coefficient of variation of the particle size of the conductive particles is 20% or less.

In a specific aspect of the conductive particles according to the present invention, when the metal particles do not contain or contain a resin and the metal particles contain a resin, the content of the resin in 100% by weight of the metal particles Is 10% by weight or less.

In a specific aspect of the conductive particles according to the present invention, the particle size of the conductive particles is 0.1 μm or more and 1000 μm or less.

In a specific aspect of the conductive particles according to the present invention, the metal constituting the metal particles contains nickel.

According to a broad aspect of the present invention, a conductive material containing the above-mentioned conductive particles and a binder resin is provided.

According to a broad aspect of the present invention, a first connection target member having a first electrode on the surface, a second connection target member having a second electrode on the surface, the first connection target member, and the above. It is provided with a connecting portion connecting the second connection target member, and the connecting portion is formed of conductive particles or a conductive material containing the conductive particles and a binder resin. Provided is a connection structure in which the conductive particles are the above-mentioned conductive particles, and the first electrode and the second electrode are electrically connected by the conductive particles.

The conductive particles according to the present invention include metal particles having a porous structure, and have the following constitution A or the following constitution B. Configuration A: The specific surface area of the conductive particles is 10 m ² / g or more. Configuration B: The specific surface area of the conductive particles ^{is less than 10 m 2} / g, and the specific gravity is 1 g / cm ³ or more and 8 g / cm ³ or less. Since the conductive particles according to the present invention have the above-mentioned structure, 1) the connection resistance between the electrodes in the vertical direction to be connected can be effectively reduced, and 2) they must not be connected. The insulation reliability between the electrodes in the lateral direction can be improved, and 3) the withstand current characteristics can be improved.

FIG. 1 is a cross-sectional view schematically showing conductive particles according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing the conductive particles according to the second embodiment of the present invention. FIG. 3 is a cross-sectional view schematically showing the conductive particles according to the third embodiment of the present invention. FIG. 4 is a cross-sectional view schematically showing the conductive particles according to the fourth embodiment of the present invention. FIG. 5 is a cross-sectional view schematically showing the conductive particles according to the fifth embodiment of the present invention. FIG. 6 is a cross-sectional view showing an example of a connection structure using conductive particles according to the first embodiment of the present invention.

The details of the present invention will be described below.

(Conductive particles)
The conductive particles according to the present invention include metal particles having a porous structure, and have the following constitution A or the following constitution B. The porous structure means a structure having a plurality of pores.

Since the conductive particles according to the present invention have the above-mentioned configuration, when the electrodes are electrically connected, 1) the connection resistance between the electrodes in the vertical direction to be connected is effectively reduced. 2) Insulation reliability between the lateral electrodes that should not be connected can be enhanced, and 3) withstand current characteristics can be enhanced.

Since the conductive particles according to the present invention are provided with metal particles having a porous structure and are provided with a specific configuration A or configuration B, the conductive particles are satisfactorily compressed at the time of connection between the electrodes in the vertical direction. Conductive paths are well formed not only on the surface of the compressed conductive particles (for example, the conductive portion) but also inside the conductive particles. Therefore, the conductive particles according to the present invention can exhibit all the effects of 1) -3) described above.

Further, in the conventional conductive particles using metal particles as the base material particles, the elasticity of the conductive particles is low, so that the conductive particles may deeply dig into the electrode and damage the electrode. On the other hand, in the conductive particles according to the present invention, the elasticity of the conductive particles can be increased, so that the risk of damage to the electrodes can be suppressed.

The conductive particles according to the present invention may or may not have a conductive portion arranged on the outer surface of the metal particles having a porous structure. The conductive particles according to the present invention may be conductive particles having only metal particles having a porous structure. That is, the metal particles themselves having a porous structure may be the conductive particles according to the present invention. Further, the conductive particles according to the present invention may be conductive particles including metal particles having a porous structure and conductive portions arranged on the outer surface of the metal particles. That is, the metal particles may be base particles. The conductive particles according to the present invention may include the above-mentioned metal particles as base particles.

In the present specification, the conductive particles having the constitution A may be referred to as "conductive particles (A)", and the conductive particles having the constitution B may be referred to as "conductive particles (B)". I have something to do.

The specific surface area of the conductive particles (A) is 10 m ² / g or more. The specific surface area of the conductive particles (A) is preferably 15 m ² / g or more, more preferably 20 m ² / g or more, preferably 5000 m ² / g or less, and more preferably 1000 m ² / g or less. When the specific surface area of the conductive particles (A) is equal to or greater than the above lower limit and equal to or less than the above upper limit, the conductive particles are more satisfactorily compressed when connected between the electrodes in the vertical direction, and the inside of the compressed conductive particles is further compressed. The conduction path can be formed even better, and the effect of the present invention can be exhibited even more effectively.

The specific surface area of the conductive particles (B) is less than ^{10 m 2 / g.} The specific surface area of the conductive particles (B) is preferably 0.5 m ² / g or more, more preferably 1.0 m ² / g or more, still more preferably 1.2 m ² / g or more, and preferably 8 m ^{2 or more.} It is / g or less, more preferably 5 m ² / g or less. When the specific surface area of the conductive particles (B) is equal to or greater than the above lower limit and equal to or less than the above upper limit, the conductive particles are more satisfactorily compressed when connected between the electrodes in the vertical direction, and the inside of the compressed conductive particles is further compressed. The conduction path can be formed even better, and the effect of the present invention can be exhibited even more effectively.

The specific surface area of the conductive particles means the BET specific surface area. The BET specific surface area of the conductive particles can be measured from the adsorption isotherm of nitrogen in accordance with the BET method. Examples of the BET specific surface area measuring device include "NOVA4200e" manufactured by Cantachrome Instruments.

The specific surface area of the conductive particles can be controlled by changing the porous structure of the metal particles, the coverage of the conductive portion arranged on the outer surface of the metal particles, and the like.

The specific gravity of the conductive particles (A) is not particularly limited. The specific gravity of the conductive particles (A) may be 1 g / cm ³ or more, or 20 g / cm ³ or less.

The specific gravity of the conductive particles (B) is 1 g / cm ³ or more and 8 g / cm ³ or less. The specific gravity of the conductive particles (B) is preferably 1.5 g / cm ³ or more, more preferably 2 g / cm ³ or more, preferably 7 g / cm ³ or less, and more preferably 6 g / cm ³ or less. .. When the specific gravity of the conductive particles (B) is equal to or higher than the lower limit and lower than the upper limit, the conductive particles are more satisfactorily compressed when connected between the electrodes in the vertical direction, and the inside of the compressed conductive particles is further compressed. The conduction path can be formed even better, and the effect of the present invention can be exhibited even more effectively.

The specific gravity of the conductive particles can be measured using a true hydrometer or the like.

The particle size of the conductive particles is preferably 0.1 μm or more, more preferably 1 μm or more, preferably 1000 μm or less, more preferably 500 μm or less, still more preferably 100 μm or less, still more preferably 50 μm or less, and even more. It is preferably 20 μm or less, and particularly preferably 10 μm or less. When the particle diameter of the conductive particles is equal to or greater than the above lower limit and equal to or less than the above upper limit, the contact area between the conductive particles and the electrodes becomes sufficiently large when the electrodes are connected using the conductive particles, and the conductivity is increased. It becomes difficult to form agglomerated conductive particles when forming the portion. In addition, the distance between the electrodes connected via the conductive particles does not become too large, and the conductive portion does not easily peel off from the surface of the resin particles. Further, when the particle size of the conductive particles is not less than the above lower limit and not more than the above upper limit, the conductive particles can be suitably used for the use of the conductive material.

The particle size of the conductive particles means the diameter when the conductive particles are spherical, and when the conductive particles have a shape other than spherical, it is assumed to be a true sphere corresponding to the volume. Means the diameter of. The particle size of the conductive particles means the particle size of the metal particles when the conductive particles include only the metal particles having a porous structure, and the metal particles in which the conductive particles have a porous structure and the metal particles. When the metal particles are provided with the conductive portion arranged on the outer surface, it means the total of the particle diameter of the metal particles and the thickness of the conductive portion (usually twice the thickness of the conductive portion).

The particle size of the conductive particles is preferably an average particle size, and more preferably a number average particle size. The particle size of the conductive particles can be determined by observing 50 arbitrary conductive particles with an electron microscope or an optical microscope, calculating the average value of the particle size of each conductive particle, or using a particle size distribution measuring device. Desired. In observation with an electron microscope or an optical microscope, the particle size of each conductive particle is determined as the particle size in the equivalent circle diameter. In observation with an electron microscope or an optical microscope, the average particle diameter of any 50 conductive particles in the equivalent circle diameter is substantially equal to the average particle diameter in the equivalent diameter of the sphere. In the particle size distribution measuring device, the particle size of each conductive particle is obtained as the particle size in the equivalent diameter of a sphere. The particle size of the conductive particles is preferably calculated using a particle size distribution measuring device.

The coefficient of variation (CV value) of the particle size of the conductive particles is preferably 20% or less, more preferably 10% or less, still more preferably 5% or less. When the coefficient of variation of the particle size of the conductive particles is not more than the above upper limit, the conduction reliability and the insulation reliability between the electrodes can be further effectively improved. Although it is difficult to reduce the fluctuation coefficient of the particle size of the conductive particles in the conventional conductive particles including the metal particles as the base particles, in the conductive particles according to the present invention, the fluctuation coefficient of the particle size is set. It can be made smaller.

The coefficient of variation (CV value) can be measured as follows.

CV value (%) = (ρ / Dn) × 100
ρ: Standard deviation of particle size of conductive particles Dn: Average value of particle size of conductive particles

10% K value of the conductive particles (compression modulus of when compressed by 10%) is preferably 100 N / mm ² or more, more preferably 1000 N / mm ² or more, preferably 25000N / mm ² or less, more It is preferably 20000 N / mm ² or less. When the 10% K value of the conductive particles is not less than the above lower limit and not more than the above upper limit, the connection resistance between the electrodes can be further effectively lowered, and the occurrence of cracking of the conductive particles is further effective. It is possible to further effectively improve the connection reliability between the electrodes.

30% K value of the conductive particles (compression modulus of when compressed 30%) is preferably 100 N / mm ² or more, more preferably 1000 N / mm ² or more, preferably 15000 N / mm ² or less, more It is preferably 10000 N / mm ² or less. When the 30% K value of the conductive particles is not less than the above lower limit and not more than the above upper limit, the connection resistance between the electrodes can be further effectively lowered, and the occurrence of cracking of the conductive particles is further effective. It is possible to further effectively improve the connection reliability between the electrodes.

The ratio of the 10% K value of the conductive particles to the 30% K value of the conductive particles (10% K value of the conductive particles / 30% K value of the conductive particles) is preferably 1.5 or more. It is more preferably 1.55 or more, preferably 5 or less, and more preferably 4.5 or less. When the above ratio (10% K value of conductive particles / 30% K value of conductive particles) is equal to or more than the above lower limit and less than or equal to the above upper limit, the connection resistance between the electrodes can be further effectively lowered. The occurrence of cracking of the conductive particles can be suppressed more effectively, and the connection reliability between the electrodes can be further effectively enhanced.

The 10% K value and the 30% K value of the conductive particles can be measured as follows.

Using a microcompression tester, compress one conductive particle on a smoothing indenter end face of a cylinder (diameter 100 μm, made of diamond) under the conditions of 25 ° C., a compression rate of 0.3 mN / sec, and a maximum test load of 20 mN. .. At this time, the load value (N) and the compressive displacement (mm) are measured. From the obtained measured values, the compressive elastic modulus (10% K value and 30% K value) can be calculated by the following formula. As the microcompression tester, "Fisherscope H-100" manufactured by Fisher Co., Ltd. or the like is used. The 10% K value and the 30% K value of the conductive particles can be calculated by arithmetically averaging the 10% K value and the 30% K value of 50 arbitrarily selected conductive particles. preferable.

10% K value and 30% K value (N / mm ² ) = (3/2 ^1/2 ) ・ F ・ S ^-3/2・ R- ^{1 / 2}
F: Load value (N) when the conductive particles are compressed and deformed by 10% or 30%.
S: Compressive displacement (mm) when conductive particles are compressed and deformed by 10% or 30%
R: Radius of conductive particles (mm)

The compressive elastic modulus universally and quantitatively represents the hardness of conductive particles. By using the compressive elastic modulus, the hardness of the conductive particles can be expressed quantitatively and uniquely. Further, the above ratio (10% K value of the conductive particles / 30% K value of the conductive particles) can quantitatively and uniquely represent the physical properties of the conductive particles at the time of initial compression.

The shape of the conductive particles is not particularly limited. The shape of the conductive particles may be spherical, non-spherical, flat or the like.

Hereinafter, the present invention will be specifically described with reference to the drawings.

FIG. 1 is a cross-sectional view schematically showing conductive particles according to the first embodiment of the present invention.

The conductive particle 1 shown in FIG. 1 has a metal particle 2 and a conductive portion 3. The metal particles 2 are base particles. The metal particles 2 have a porous structure (not shown). The metal particle 2 has a plurality of pores. The conductive portion 3 is arranged on the outer surface of the metal particles 2. The conductive portion 3 is partially arranged on the outer surface of the metal particles 2. The conductive portion 3 covers a part of the outer surface of the metal particles 2. In the conductive particles 1, the conductive portion 3 covers a part of the outer surface of the metal particles 2. The conductive portion 3 is a single conductive layer. The conductive portion 3 is a discontinuous layer. The conductive portion 3 is in contact with the surface of the metal particles 2. In the metal particles 2, there is a portion that is not covered by the conductive portion 3. Since the metal particles 2 have a porous structure and the conductive portion 3 is partially arranged on the outer surface of the metal particles 2, the specific surface area of the conductive particles 1 is relatively large. The conductive particle 1 is the conductive particle (A). The conductive particles may be conductive particles (B) having the structure of the conductive particles 1. Further, in the conductive particles, the conductive portion may be a single-layer conductive layer or a multi-layer conductive layer composed of two or more layers.

FIG. 2 is a cross-sectional view schematically showing the conductive particles according to the second embodiment of the present invention.

The conductive particle 1A shown in FIG. 2 has a metal particle 2 and a conductive portion 3A. In the conductive particles 1A, unlike the conductive particles 1 shown in FIG. 1, the conductive portion 3A is arranged so as to cover the entire outer surface of the metal particles 2. The conductive portion 3A covers the entire outer surface of the metal particles 2. In the conductive particles 1A, the conductive portion 3A covers the entire outer surface of the metal particles 2. The conductive portion 3A is a continuous layer. In the conductive particles 1A, since the conductive portion 3A is arranged on the entire outer surface of the metal particles 2, the specific surface area of the conductive particles 1A is smaller than the specific surface area of the conductive particles 1. The conductive particles 1A are the conductive particles (B). The conductive particles may be the conductive particles (A) having the structure of the conductive particles 1A. Further, in the conductive particles, the conductive portion may be a single-layer conductive layer or a multi-layer conductive layer composed of two or more layers.

FIG. 3 is a cross-sectional view schematically showing the conductive particles according to the third embodiment of the present invention.

The conductive particle 1B shown in FIG. 3 has a metal particle 2, a conductive portion 3B, a plurality of core substances 4, and a plurality of insulating substances 5. The conductive portion 3B is arranged on the surface of the metal particles 2 so as to be in contact with the metal particles 2.

The conductive portion 3B is a single conductive layer. The conductive portion 3B is arranged so as to cover the entire outer surface of the metal particles 2. The conductive portion may cover the entire surface of the metal particles, or may cover a part of the surface of the metal particles. In the conductive particles, the conductive portion may be a single-layer conductive layer or a multi-layer conductive layer composed of two or more layers.

The conductive particles 1B have a plurality of protrusions 1Ba on the outer surface. The conductive portion 3B has a plurality of protrusions 3Ba on the outer surface. A plurality of core substances 4 are arranged on the surface of the metal particles 2. The plurality of core substances 4 are embedded in the conductive portion 3B. The core material 4 is arranged inside the protrusions 1Ba and 3Ba. The conductive portion 3B covers a plurality of core substances 4. The outer surface of the conductive portion 3B is raised by the plurality of core substances 4, and protrusions 1Ba and 3Ba are formed.

The conductive particles 1B have an insulating substance 5 arranged on the outer surface of the conductive portion 3B. At least a part of the outer surface of the conductive portion 3B is covered with the insulating substance 5. The insulating substance 5 is formed of an insulating material and is an insulating particle. As described above, the conductive particles according to the present invention may have an insulating substance arranged on the outer surface of the conductive portion. However, the conductive particles according to the present invention do not necessarily have an insulating substance.

FIG. 4 is a cross-sectional view schematically showing the conductive particles according to the fourth embodiment of the present invention.

The conductive particle 1C shown in FIG. 4 has a metal particle 2, a conductive portion 3C, a plurality of core substances 4, and a plurality of insulating substances 5. As a whole, the conductive portion 3C has a first conductive portion 31C on the metal particle 2 side and a second conductive portion 32C on the side opposite to the metal particle 2 side.

Only the conductive part is different between the conductive particles 1B and the conductive particles 1C. That is, in the conductive particles 1B, the conductive portion 3B having a one-layer structure is formed, whereas in the conductive particles 1C, the first conductive portion 31C and the second conductive portion 32C having a two-layer structure are formed. ing. The first conductive portion 31C and the second conductive portion 32C are formed as separate conductive portions.

The first conductive portion 31C is arranged on the surface of the metal particles 2. A first conductive portion 31C is arranged between the metal particles 2 and the second conductive portion 32C. The first conductive portion 31C is in contact with the metal particles 2. The second conductive portion 32C is in contact with the first conductive portion 31C. Therefore, the first conductive portion 31C is arranged on the surface of the metal particles 2, and the second conductive portion 32C is arranged on the surface of the first conductive portion 31C. The conductive particles 1C have a plurality of protrusions 1Ca on the outer surface. The conductive portion 3C has a plurality of protrusions 3Ca on the outer surface. The first conductive portion 31C has a plurality of protrusions 31Ca on the outer surface. The second conductive portion 32C has a plurality of protrusions 32Ca on the outer surface.

FIG. 5 is a cross-sectional view schematically showing the conductive particles according to the fifth embodiment of the present invention.

The conductive particle 1D shown in FIG. 5 is a metal particle 2. The conductive particles 1D are conductive particles including only the metal particles 2. The metal particles 2 themselves are conductive particles. The conductive particles 1D do not have a conductive portion.

Hereinafter, other details of the conductive particles will be described.

(Metal particles)
The metal particles have a porous structure. The metal particles have a plurality of pores. The metal particles have voids. The metal particles are particles made of metal. However, the metal particles may contain a resin. The shape of the metal particles is not particularly limited. The shape of the metal particles may be spherical, non-spherical, flat or the like.

The metal constituting the metal particles is not particularly limited. As the metal constituting the metal particles, only one kind may be used, or two or more kinds may be used in combination.

The metals constituting the metal particles include gold, silver, palladium, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, tarium, germanium, cadmium, and the like. Examples thereof include silicon, tungsten, molybdenum and alloys thereof.

From the viewpoint of more effectively exerting the effects of the present invention, the metal constituting the metal particles preferably contains nickel, gold or palladium, more preferably nickel, and further preferably nickel. preferable.

The content of the metal in 100% by weight of the metal particles is preferably 60% by weight or more, more preferably 70% by weight or more, still more preferably 80% by weight or more, and most preferably 100% by weight. When the content of the metal is at least the above lower limit, the effect of the present invention can be exhibited even more effectively. The content of the metal in 100% by weight of the metal particles may be 100% by weight or less, 99% by weight or less, or 95% by weight or less.

The metal particles do not contain or contain resin. The metal particles may or may not contain a resin. The resin contained in the metal particles is, for example, a residual component of the resin used when producing the metal particles having a porous structure. When the metal particles contain the resin, it is preferable that the resin is uniformly distributed in the metal particles.

Examples of the resin include polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene and polybutadiene; acrylic resins such as polymethylmethacrylate and polymethylacrylate; polycarbonate, polyamide, phenolformaldehyde resin and melamine formaldehyde. Resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polyethylene terephthalate, polysulfone, polyphenylene oxide, polyacetal, polyimide, polyamideimide, poly Examples thereof include ether ether ketone, polyether sulfone, and divinylbenzene polymer. The divinylbenzene polymer may be a divinylbenzene copolymer. Examples of the divinylbenzene copolymer and the like include a divinylbenzene-styrene copolymer and a divinylbenzene- (meth) acrylic acid ester copolymer.

The smaller the content of the resin in the metal particles, the better. When the metal particles contain a resin, the content of the resin in 100% by weight of the metal particles is preferably 10% by weight or less, more preferably 5% by weight or less, still more preferably 1% by weight or less. When the content of the resin is not more than the above upper limit, the effect of the present invention can be exhibited even more effectively. Most preferably, the metal particles do not contain the resin.

The content of the resin in the metal particles is calculated by the formula: 100% by weight-metal content (% by weight) after measuring the metal content (% by weight) in the metal particles by ICP emission spectrometry. It can be obtained by doing.

The particle size of the metal particles is preferably 0.1 μm or more, more preferably 1 μm or more, preferably 1000 μm or less, more preferably 500 μm or less, still more preferably 100 μm or less, still more preferably 50 μm or less, even more preferably. Is 20 μm or less, particularly preferably 10 μm or less. When the particle diameter of the metal particles is equal to or greater than the above lower limit and equal to or less than the above upper limit, the contact area between the conductive particles and the electrodes becomes sufficiently large and the conductive portion is formed when the electrodes are connected using the conductive particles. It becomes difficult for agglomerated conductive particles to be formed when the particles are formed. Further, when the conductive portion is formed on the surface of the metal particles by electroless plating, it is possible to make it difficult for the agglomerated conductive particles to be formed. Further, when the particle size of the metal particles is not less than the above lower limit and not more than the above upper limit, the conductive particles are easily sufficiently compressed, the connection resistance between the electrodes can be further reduced, and the distance between the electrodes can be further increased. It can be made smaller.

The particle diameter of the metal particles means the diameter when the metal particles are spherical, and when the metal particles have a shape other than the spherical shape, the diameter when the metal particles are assumed to be a true sphere corresponding to the volume. means.

The particle size of the metal particles is preferably an average particle size, more preferably a number average particle size. The particle size of the metal particles can be obtained by observing 50 arbitrary metal particles with an electron microscope or an optical microscope, calculating the average value of the particle size of each metal particle, or using a particle size distribution measuring device. In observation with an electron microscope or an optical microscope, the particle size of each metal particle is determined as the particle size in the equivalent circle diameter. In observation with an electron microscope or an optical microscope, the average particle diameter of any 50 metal particles in the equivalent circle diameter is substantially equal to the average particle diameter in the equivalent diameter of the sphere. In the particle size distribution measuring device, the particle size of each metal particle is obtained as the particle size in the equivalent diameter of a sphere. The average particle size of the metal particles is preferably calculated using a particle size distribution measuring device. When measuring the particle size of the metal particles in the conductive particles, for example, the measurement can be performed as follows.

Add to "Technobit 4000" manufactured by Kulzer so that the content of conductive particles is 30% by weight and disperse to prepare an embedded resin body for conducting conductive particle inspection. A cross section of the conductive particles is cut out using an ion milling device (“IM4000” manufactured by Hitachi High-Technologies Corporation) so as to pass near the center of the conductive particles dispersed in the embedded resin body for inspection. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification is set to 25000 times, 50 conductive particles are randomly selected, and the metal particles in each conductive particle are observed. .. The particle size of the metal particles in each conductive particle is measured, and they are arithmetically averaged to obtain the particle size of the metal particles.

The coefficient of variation (CV value) of the particle size of the metal particles is preferably 20% or less, more preferably 10% or less, still more preferably 5% or less. When the coefficient of variation of the particle size of the metal particles is not more than the above upper limit, the conduction reliability and the insulation reliability between the electrodes can be further effectively improved.

The coefficient of variation (CV value) can be measured as follows.

CV value (%) = (ρ / Dn) × 100
ρ: Standard deviation of particle size of metal particles Dn: Average value of particle size of metal particles

The total pore volume of the metal particles is preferably 0.01 cm ³ / g or more, more preferably 0.1 cm ³ / g or more, preferably 3 cm ³ / g or less, and more preferably 1.5 cm ³ / g. It is as follows. When the total pore volume is equal to or higher than the lower limit and lower than the upper limit, the conductive particles are more satisfactorily compressed when the electrodes are connected in the vertical direction, and a conduction path is provided inside the compressed conductive particles. It can be formed even better, and the effects of the present invention can be exhibited even more effectively. Further, when the total pore volume is equal to or more than the above lower limit and not more than the above upper limit, the adhesion between the metal particles and the conductive portion can be further effectively enhanced, and the occurrence of peeling of the conductive portion is further effective. Can be suppressed.

The average pore diameter of the metal particles is preferably 0.1 nm or more, more preferably 0.5 nm or more, preferably 10 nm or less, and more preferably 5 nm or less. When the average pore diameter is equal to or greater than the above lower limit and equal to or less than the above upper limit, the conductive particles are more satisfactorily compressed when the electrodes are connected in the vertical direction, and a conduction path is provided inside the compressed conductive particles. It can be formed more satisfactorily, and the effect of the present invention can be exhibited even more effectively. Further, when the average pore diameter is at least the above lower limit and at least the above upper limit, the adhesion between the metal particles and the conductive portion can be further effectively enhanced, and the occurrence of peeling of the conductive portion can be further effectively performed. It can be suppressed.

The total pore volume and average pore diameter of the metal particles can be measured from the adsorption isotherm of nitrogen in accordance with the BJH method. Examples of the measuring device that can be used for measuring the total pore volume and the average pore diameter include "NOVA4200e" manufactured by Cantachrome Instruments.

The porosity of the metal particles is preferably 10% or more, more preferably 20% or more, preferably 70% or less, and more preferably 50% or less. When the porosity is equal to or higher than the lower limit and lower than the upper limit, the conductive particles are compressed more satisfactorily at the time of connection between the electrodes in the vertical direction, and the conduction path is further provided inside the compressed conductive particles. It can be formed well, and the effects of the present invention can be exhibited even more effectively. Further, when the porosity is equal to or higher than the lower limit and lower than the upper limit, the adhesion between the metal particles and the conductive portion can be further effectively enhanced, and the occurrence of peeling of the conductive portion can be further effectively suppressed. can do.

The porosity of the metal particles can be calculated by measuring the cumulative amount of mercury infiltrated with respect to the pressure applied by the mercury intrusion method. Examples of the measuring device that can be used for measuring the porosity include a mercury porosimeter "Poremaster 60" manufactured by Cantachrome Instruments.

<Method for producing metal particles having a porous structure>
The method for producing the metal particles having a porous structure is not particularly limited. Metal particles having a porous structure are produced by impregnating metal particle-forming base particles with metal and then removing the base particle components (resin component, etc.) of the metal particle-forming base particles containing metal. Is preferable. Therefore, the material of the base particles for forming metal particles is preferably an organic material, and more preferably a resin. Examples of the base particle for forming metal particles formed only of the organic material include resin particles.

From the viewpoint of obtaining the metal particles having a porous structure satisfactorily, the base particles for forming the metal particles are more preferably resin particles. Examples of the organic material include the above-mentioned resins. Since the metal particles having a porous structure can be obtained satisfactorily, the material of the base particles for forming the metal particles is obtained by polymerizing one or more kinds of polymerizable monomers having an ethylenically unsaturated group. It is preferably a polymer.

When the base material particles for forming metal particles are obtained by polymerizing a polymerizable monomer having an ethylenically unsaturated group, the polymerizable monomer having an ethylenically unsaturated group is a non-crosslinkable simple monomer. Examples include polymers and crosslinkable monomers.

Examples of the non-crosslinkable monomer include styrene monomers such as styrene, α-methylstyrene, and chlorostyrene; vinyl ether compounds such as methylvinyl ether, ethylvinyl ether, and propylvinyl ether; vinyl acetate, vinyl butyrate, and the like. Acid vinyl ester compounds such as vinyl laurate and vinyl stearate; halogen-containing monomers such as vinyl chloride and vinyl fluoride; as (meth) acrylic compounds, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) ) Acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate and other alkyl ( Meta) acrylate compound; oxygen atom-containing (meth) acrylate compound such as 2-hydroxyethyl (meth) acrylate, glycerol (meth) acrylate, polyoxyethylene (meth) acrylate, glycidyl (meth) acrylate; (meth) acrylonitrile, etc. Nitrile-containing monomer; Halogen-containing (meth) acrylate compound such as trifluoromethyl (meth) acrylate and pentafluoroethyl (meth) acrylate; olefin such as diisobutylene, isobutylene, linearene, ethylene and propylene as α-olefin compound Compound: Examples of the conjugated diene compound include isoprene and butadiene.

Examples of the crosslinkable monomer include vinyl monomers such as divinylbenzene, 1,4-dibinyloxybutane, and divinylsulfone as vinyl compounds; and tetramethylolmethanetetra (meth) acrylate as (meth) acrylic compounds. , Polytetramethylene glycol diacrylate, Tetramethylolmethanetri (meth) acrylate, Tetramethylolmethanedi (meth) acrylate, Trimethylolpropanetri (meth) acrylate, Dipentaerythritol hexa (meth) acrylate, Dipentaerythritol penta (meth) ) Acrylic, glycerol tri (meth) acrylate, glycerol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, 1,4-butanediol di Polyfunctional (meth) acrylate compounds such as (meth) acrylate; as allyl compounds, triallyl (iso) cyanurate, triallyl trimellitate, diallylphthalate, diallylacrylamide, diallyl ether; as silane compounds, tetramethoxysilane, tetraethoxysilane , Methyltrimethoxysilane, Methyltriethoxysilane, Ethyltrimethoxysilane, Ethyltriethoxysilane, Isopropyltrimethoxysilane, Isobutyltrimethoxysilane, Cyclohexyltrimethoxysilane, n-hexyltrimethoxysilane, n-octyltriethoxysilane, n-decyltrimethoxysilane, phenyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diisopropyldimethoxysilane, trimethoxysilylstyrene, γ- (meth) acryloxipropyltrimethoxysilane, 1,3-divinyltetramethyldi Silane alkoxide compounds such as siloxane, methylphenyldimethoxysilane, diphenyldimethoxysilane; vinyltrimethoxysilane, vinyltriethoxysilane, dimethoxymethylvinylsisilane, dimethoxyethylvinylsilane, diethoxymethylvinylsilane, diethoxyethylvinylsilane, ethylmethyldivinylsilane , Methylvinyldimethoxysilane, ethylvinyldimethoxysilane, methylvinyldiethoxysilane, ethylvinyldiethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylme Polymerizable double bond-containing silane alkoxides such as tildimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxipropyltrimethoxysilane Cyclic siloxane such as decamethylcyclopentasiloxane; modified (reactive) silicone oil such as one-terminal modified silicone oil, double-ended silicone oil, side chain type silicone oil; (meth) acrylic acid, maleic acid, maleic anhydride, etc. Examples thereof include the carboxyl group-containing monomer of.

The base particles for forming metal particles can be obtained by polymerizing the polymerizable monomer having an ethylenically unsaturated group. The above polymerization method is not particularly limited, and examples thereof include known methods such as radical polymerization, ionic polymerization, polycondensation (condensation polymerization, polycondensation polymerization), addition condensation, living polymerization, and living radical polymerization. Further, as another polymerization method, suspension polymerization in the presence of a radical polymerization initiator can be mentioned.

The method of containing a metal (conductive metal) inside the base particle for forming metal particles is not particularly limited. As a method of containing a metal inside the metal particle forming base particle, a method of electroless plating using the metal particle forming base particle which is a porous particle and a method for forming a metal particle which is a porous particle are used. Examples thereof include a method of electroplating using base particles. Since the base particles for forming metal particles, which are porous particles, have a relatively large number of voids inside the base particles, when the metal is coated on the surface of the base particles for forming metal particles, the base particles are said to be used. A metal particle-forming material (plating solution, etc.) can be allowed to enter into the fine voids inside the base particles. By precipitating the metal from the metal particle-forming material that has entered the inside of the metal particle-forming base particle, the metal can be easily contained in the metal particle-forming base particle. Examples of the constituent metal include the above-mentioned metals.

Examples of the method for removing the base particle component of the base particle for forming metal particles containing metal include heating and melting. It is preferable to heat or dissolve the base particle for forming metal particles containing metal to remove the base particle component.

As described above, metal particles having a porous structure can be produced.

(Conductive part)
The conductive particles preferably include a conductive portion arranged on the outer surface of the metal particles. The conductive portion preferably contains a metal. The conductive portion is preferably a metal-coated portion. The conductive portion is different from the metal particles. The metal constituting the conductive portion is not particularly limited. The metal constituting the conductive portion and the metal constituting the metal particles may be the same or different. The main metal constituting the conductive portion and the main metal constituting the metal particles may be the same or different. The main metal constituting the conductive portion means the metal having the highest content among the metals constituting the conductive portion. The main metal constituting the metal particles means the metal having the highest content among the metals constituting the metal particles.

The metals constituting the conductive portion include gold, silver, palladium, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, tarium, germanium, cadmium, and the like. Examples thereof include silicon, tungsten, molybdenum and alloys thereof. Examples of the metal constituting the conductive portion include tin-doped indium oxide (ITO) and solder. As the metal constituting the conductive portion, only one kind may be used, or two or more kinds may be used in combination.

From the viewpoint of further effectively lowering the connection resistance between the electrodes, the conductive portion preferably contains nickel, gold, palladium, silver, or copper, and more preferably nickel, gold, or palladium. It is particularly preferable to contain nickel.

The content of nickel in 100% by weight of the conductive portion containing nickel is preferably 10% by weight or more, more preferably 50% by weight or more, still more preferably 60% by weight or more, still more preferably 70% by weight or more, particularly preferably. Is 90% by weight or more. The content of nickel in 100% by weight of the conductive portion containing nickel may be 97% by weight or more, 97.5% by weight or more, 98% by weight or more, 100% by weight. It may be% by weight.

In addition, hydroxyl groups are often present on the surface of the conductive part due to oxidation. Generally, a hydroxyl group is present on the surface of a conductive portion formed of nickel due to oxidation. An insulating substance can be arranged on the surface of the conductive portion having such a hydroxyl group (the surface of the conductive particles) via a chemical bond. Even when a hydroxyl group is present on the surface of the metal particles, the insulating substance can be arranged on the surface of the metal particles via a chemical bond.

The conductive portion may be a discontinuous layer or a continuous layer. When the conductive portion is a discontinuous layer, conductive particles (A) can be obtained satisfactorily. When the conductive portion is a continuous layer, conductive particles (B) can be obtained satisfactorily. However, the conductive particles may be conductive particles (B) having a conductive portion which is a discontinuous layer, or may be conductive particles (A) having a conductive portion which is a continuous layer.

The conductive portion may be formed by one layer. The conductive portion may be formed of a plurality of layers. That is, the conductive portion may have a laminated structure of two or more layers. When the conductive portion is formed of a plurality of layers, the metal constituting the outermost layer is preferably gold, nickel, palladium, copper or an alloy containing tin and silver, and is preferably gold. More preferred. When the metal constituting the outermost layer is these preferred metals, the connection resistance between the electrodes becomes even lower. Further, when the metal constituting the outermost layer is gold, the corrosion resistance is further improved. The metal constituting the outermost layer may be nickel.

The area of the portion where the conductive portion is located (covering ratio of the conductive portion) in the outer surface area of 100% of the metal particles is not particularly limited. The coverage of the conductive portion can be appropriately changed depending on the specific surface area, specific gravity, etc. of the target conductive particles. The coverage of the conductive portion can be adjusted by adjusting the composition of the plating solution, the reaction conditions, and the like. In the outer surface area of the metal particles of 100%, the area of the portion where the conductive portion is present (coverage of the conductive portion) may be 0% or more, 50% or more, 90% or more. It may be 100%.

The area of the portion where the conductive portion is located (coverage of the conductive portion) in the outer surface area of the metal particles of 100% is calculated by performing element mapping by SEM-EDX analysis of the cross section of the conductive particles and image analysis. can do.

The method of forming the conductive portion on the surface of the metal particles is not particularly limited. Examples of the method for forming the conductive portion include a method by electroless plating, a method by electroplating, a method by physical collision, a method by mechanochemical reaction, a method by physical vapor deposition or physical adsorption, and a metal powder or metal powder. Examples thereof include a method of coating the surface of metal particles with a paste containing the binder and the binder. The method for forming the conductive portion is preferably a method by electroless plating, electroplating or physical collision. Examples of the method by physical vapor deposition include methods such as vacuum deposition, ion plating, and ion sputtering. Further, as the method by the above physical collision, a seater composer (manufactured by Tokuju Kosakusho Co., Ltd.) or the like is used.

From the viewpoint of easily forming a good conductive portion in order to effectively exert the effect of the present invention, the conductive portion is preferably a plated conductive portion or a sputtering conductive portion. The conductive portion may be a plated conductive portion or a sputtering conductive portion. The plating conductive portion is formed by plating. The sputtering conductive portion is formed by sputtering. The plated conductive portion is preferably a plated conductive layer. The plated conductive portion is preferably a plated metal coating portion, and more preferably a plated metal coating layer. The sputtering conductive portion is preferably a sputtering conductive layer. The sputtering conductive portion is preferably a sputtering metal coating portion, and more preferably a sputtering metal coating layer. The conductive portion does not have to have a porous structure. A conductive portion having no porous structure can be formed by plating, sputtering, or the like.

When the configuration A is provided, that is, in the case of the conductive particles (A), the thickness of the conductive portion is preferably 0.1 nm or more, more preferably 10 nm or more, preferably less than 50 nm, more preferably. It is 40 nm or less, more preferably 30 nm or less. The thickness of the conductive portion is the thickness of the entire conductive portion when the conductive portion has multiple layers. When the thickness of the conductive portion is not less than the above lower limit and not more than the above upper limit, sufficient conductivity can be obtained, and the conductive particles are not too hard and the conductive particles are sufficiently deformed at the time of connection between the electrodes. Can be made to.

When the above configuration B is provided, that is, in the case of the conductive particles (B), the thickness of the conductive portion is preferably 50 nm or more, more preferably 60 nm or more, preferably 1000 nm or less, more preferably 500 nm or less. , More preferably 300 nm or less. The thickness of the conductive portion is the thickness of the entire conductive portion when the conductive portion has multiple layers. When the thickness of the conductive portion is not less than the above lower limit and not more than the above upper limit, sufficient conductivity can be obtained, and the conductive particles are not too hard and the conductive particles are sufficiently deformed at the time of connection between the electrodes. Can be made to.

When the conductive portion is formed of a plurality of layers, the thickness of the conductive portion of the outermost layer is preferably 0.001 μm or more, more preferably 0.01 μm or more, preferably 0.5 μm or less, more preferably. Is 0.1 μm or less. When the thickness of the conductive portion of the outermost layer is equal to or higher than the lower limit and lower than the upper limit, the coating by the conductive portion of the outermost layer becomes uniform, the corrosion resistance becomes sufficiently high, and the connection resistance between the electrodes is sufficiently increased. Can be lowered. Further, when the metal constituting the outermost layer is gold, the thinner the outermost layer, the lower the cost.

The thickness of the conductive portion can be measured by observing the cross section of the conductive particles using, for example, a transmission electron microscope (TEM). Regarding the thickness of the conductive portion, it is preferable to calculate the average value of the thickness of any of the conductive portions at five points as the thickness of the conductive portion of one conductive particle, and the average value of the thickness of the entire conductive portion is one. It is more preferable to calculate as the thickness of the conductive portion of the conductive particles. Further, in the case of conductive particles having a portion on the outer surface of the metal particle in which the conductive portion is not arranged (for example, the conductive particle 1 in FIG. 1), the portion where the conductive portion is not arranged is the thickness of the conductive portion. The thickness of the conductive portion is obtained only from the portion where the conductive portion is arranged. When determining the thickness of the conductive portion, the boundary between the metal particles having a porous structure and the conductive portion is determined according to the following procedure. In the cross section of the substantially circular conductive particles, the smallest approximate circle that has the same center as the substantially circular circle and contains the entire metal particles having a porous structure is defined as the boundary between the metal particles and the conductive portion. .. The thickness of the conductive portion is preferably obtained by calculating the average value of the thickness of the conductive portion of each conductive particle for 50 arbitrary conductive particles.

(Core substance)
The conductive particles preferably have protrusions on the outer surface of the conductive portion. The conductive particles preferably have protrusions on the surface. It is preferable that the number of the protrusions is plurality. The conductive particles preferably have a plurality of the protrusions. An oxide film is often formed on the surface of the electrode connected by the conductive particles. When conductive particles having protrusions on the surface of the conductive portion are used, the oxide film can be effectively removed by the protrusions by arranging the conductive particles between the electrodes and crimping them. Therefore, the electrodes and the conductive portion come into contact with each other more reliably, and the connection resistance between the electrodes becomes even lower. Further, when the conductive particles include an insulating substance, or when the conductive particles are dispersed in a binder resin and used as a conductive material, the protrusions of the conductive particles between the conductive particles and the electrode. Insulating substances or binder resins can be eliminated even more effectively. Therefore, the connection resistance between the electrodes can be further reduced.

The method of forming the protrusions includes a method of adhering a core material to the surface of metal particles and then forming a conductive portion by electroless plating, and a method of forming a conductive portion by electroless plating on the surface of metal particles. Examples thereof include a method in which a core material is attached and a conductive portion is formed by electroless plating. Further, the core material may not be used to form the protrusions.

As another method for forming the above-mentioned protrusions, a method of adding a core substance in the middle of forming a conductive portion on the surface of the metal particles can be mentioned. Further, in order to form the protrusions, the conductive portion is formed on the metal particles by electroless plating without using the core material, and then the plating is deposited in the shape of protrusions on the surface of the conductive portion, and further by electroless plating. A method of forming a conductive portion or the like may be used.

As a method of adhering the core substance to the surface of the metal particles, a method of adding the core substance to the dispersion liquid of the metal particles and accumulating and adhering the core substance on the surface of the metal particles by van der Waals force, and Examples thereof include a method in which a core substance is added to a container containing metal particles, and the core substance is attached to the surface of the metal particles by a mechanical action such as rotation of the container. From the viewpoint of controlling the amount of the core substance to be adhered, the method of adhering the core substance to the surface of the metal particles is preferably a method of accumulating and adhering the core substance to the surface of the metal particles in the dispersion liquid.

Examples of the substance constituting the core substance include a conductive substance and a non-conductive substance. Examples of the conductive substance include metals, metal oxides, conductive non-metals such as graphite, and conductive polymers. Examples of the conductive polymer include polyacetylene and the like. Examples of the non-conductive substance include silica, alumina and zirconia. From the viewpoint of removing the oxide film more effectively, the core material is preferably hard. From the viewpoint of further effectively lowering the connection resistance between the electrodes, the core material is preferably a metal.

The above metals are not particularly limited. Examples of the metals include metals such as gold, silver, copper, platinum, zinc, iron, lead, tin, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium and cadmium, and tin-lead alloys. Examples thereof include alloys composed of two or more kinds of metals such as tin-copper alloy, tin-silver alloy, tin-lead-silver alloy and tungsten carbide. From the viewpoint of further effectively lowering the connection resistance between the electrodes, the metal is preferably nickel, copper, silver or gold. The metal may be the same as or different from the metal constituting the conductive portion (conductive layer). The metal may be the same as or different from the metal constituting the metal particles.

The shape of the core substance is not particularly limited. The shape of the core material is preferably lumpy. Examples of the core material include particulate lumps, agglomerates in which a plurality of fine particles are agglomerated, and amorphous lumps.

The particle size of the core substance is preferably 0.001 μm or more, more preferably 0.05 μm or more, preferably 0.9 μm or less, and more preferably 0.2 μm or less. When the particle size of the core substance is not less than the above lower limit and not more than the upper limit, the connection resistance between the electrodes can be further effectively reduced.

The particle size of the core substance is preferably an average particle size, more preferably a number average particle size. The particle size of the core substance can be obtained by observing 50 arbitrary core substances with an electron microscope or an optical microscope, calculating the average value of the particle size of each core substance, or using a particle size distribution measuring device. In observation with an electron microscope or an optical microscope, the particle size of each core substance is determined as the particle size in a circle-equivalent diameter. In observation with an electron microscope or an optical microscope, the average particle diameter of any 50 core materials in the equivalent circle diameter is substantially equal to the average particle diameter in the equivalent diameter of the sphere. In the particle size distribution measuring device, the particle size of each core substance is obtained as the particle size in the equivalent diameter of a sphere. The average particle size of the core substance is preferably calculated using a particle size distribution measuring device.

The number of the protrusions per conductive particle is preferably 3 or more, more preferably 5 or more. The upper limit of the number of the protrusions is not particularly limited. The upper limit of the number of protrusions can be appropriately selected in consideration of the particle size of the conductive particles and the like. When the number of the protrusions is at least the above lower limit, the connection resistance between the electrodes can be further effectively reduced.

The number of protrusions can be calculated by observing arbitrary conductive particles with an electron microscope or an optical microscope. The number of protrusions is preferably determined by observing 50 arbitrary conductive particles with an electron microscope or an optical microscope and calculating the average value of the number of protrusions in each conductive particle.

The height of the protrusion is preferably 0.001 μm or more, more preferably 0.05 μm or more, preferably 0.9 μm or less, and more preferably 0.5 μm or less. The height of the protrusion may be 0.2 μm or less. When the height of the protrusion is equal to or higher than the lower limit and lower than the upper limit, the connection resistance between the electrodes can be further effectively reduced.

The height of the protrusions can be calculated by observing the protrusions on any conductive particle with an electron microscope or an optical microscope. The height of the protrusions is preferably calculated by calculating the average value of the heights of all the protrusions per conductive particle as the height of the protrusions of one conductive particle. It is preferable that the height of the protrusions is obtained by calculating the average value of the heights of the protrusions of each conductive particle for 50 arbitrary conductive particles.

(Insulating substance)
The conductive particles preferably include an insulating substance arranged on the outer surface of the metal particles or on the outer surface of the conductive portion. In the conductive particles, an insulating substance may be arranged on the outer surface of the metal particles. It is more preferable that the conductive particles include an insulating substance arranged on the outer surface of the conductive portion. When an insulating substance is provided, if the conductive particles are used for the connection between the electrodes, a short circuit between adjacent electrodes can be prevented more effectively. Specifically, when a plurality of conductive particles come into contact with each other, an insulating substance exists between the plurality of electrodes, so that it is possible to prevent a short circuit between the electrodes adjacent to each other in the lateral direction rather than between the upper and lower electrodes. By pressurizing the conductive particles with the two electrodes when connecting the electrodes, the insulating substance between the conductive portion of the conductive particles and the electrodes can be easily removed. Further, in the case of the conductive particles having protrusions on the outer surface of the conductive portion, the insulating substance between the conductive portion of the conductive portion and the electrode can be more easily removed.

The insulating substance is preferably insulating particles because the insulating substance can be more easily removed during crimping between the electrodes. In the present specification, among the conductive particles according to the present invention, the conductive particles having insulating particles may be referred to as conductive particles with insulating particles.

Examples of the material of the insulating substance include the above-mentioned resin and inorganic substances. The material of the insulating substance is preferably the resin. As the material of the insulating substance, only one kind may be used, or two or more kinds may be used in combination.

Examples of the inorganic substances include silica, alumina, barium titanate, zirconia, carbon black, silicate glass, borosilicate glass, lead glass, soda-lime glass and alumina silicate glass.

Other materials for the insulating material include polyolefin compounds, (meth) acrylate polymers, (meth) acrylate copolymers, block polymers, thermoplastic resins, crosslinked products of thermoplastic resins, thermosetting resins and water-soluble materials. Examples include resin.

Examples of the polyolefin compound include polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer and the like. Examples of the (meth) acrylate polymer include polymethyl (meth) acrylate, polydodecyl (meth) acrylate, and polystearyl (meth) acrylate. Examples of the block polymer include polystyrene, styrene-acrylic acid ester copolymer, SB type styrene-butadiene block copolymer, SBS type styrene-butadiene block copolymer, and hydrogenated products thereof. Examples of the thermoplastic resin include vinyl polymers and vinyl copolymers. Examples of the thermosetting resin include epoxy resin, phenol resin, melamine resin and the like. Examples of the crosslinked product of the thermoplastic resin include the introduction of polyethylene glycol methacrylate, alkoxylated trimethylolpropane methacrylate, alkoxylated pentaerythritol methacrylate and the like. Examples of the water-soluble resin include polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyvinylpyrrolidone, polyethylene oxide, methyl cellulose and the like. Further, a chain transfer agent may be used to adjust the degree of polymerization. Examples of the chain transfer agent include thiols and carbon tetrachloride.

Examples of the method of arranging the insulating substance on the surface of the metal particles or the surface of the conductive portion include a chemical method and a physical or mechanical method. Examples of the chemical method include an interfacial polymerization method, a suspension polymerization method in the presence of particles, and an emulsion polymerization method. Examples of the physical or mechanical method include spray drying, hybridization, electrostatic adhesion method, spraying method, dipping and vacuum deposition methods. A method of arranging the insulating substance on the surface of the metal particles or the surface of the conductive portion from the viewpoint of further effectively enhancing the insulation reliability and the conduction reliability when the electrodes are electrically connected. Is preferably a physical method.

The outer surface of the metal particles, the outer surface of the conductive portion, and the outer surface of the insulating substance may each be coated with a compound having a reactive functional group. The outer surface of the metal particles or the outer surface of the conductive portion and the outer surface of the insulating substance do not have to be directly chemically bonded, but are indirectly chemically bonded by a compound having a reactive functional group. May be good. After introducing a carboxyl group into the outer surface of the metal particles or the outer surface of the conductive portion, the carboxyl group is chemically bonded to the functional group on the outer surface of the insulating substance via a polyelectrolyte such as polyethyleneimine. May be good.

When the insulating substance is an insulating particle, the particle size of the insulating particle can be appropriately selected depending on the particle size of the conductive particle, the application of the conductive particle, and the like. The particle size of the insulating particles is preferably 10 nm or more, more preferably 100 nm or more, further preferably 300 nm or more, particularly preferably 500 nm or more, preferably 4000 nm or less, more preferably 2000 nm or less, still more preferably 1500 nm or less. , Especially preferably 1000 nm or less. When the particle size of the insulating particles is at least the above lower limit, when the conductive particles are dispersed in the binder resin, it becomes difficult for the metal particles or the conductive portions of the plurality of conductive particles to come into contact with each other. When the particle size of the insulating particles is not more than the above upper limit, the pressure is increased in order to eliminate the insulating particles between the metal particles or the conductive portion in the electrodes and the conductive particles when connecting the electrodes. There is no need to overheat and no need to heat to high temperatures.

The particle size of the insulating particles is preferably an average particle size, and preferably a number average particle size. The particle size of the insulating particles can be obtained by observing 50 arbitrary insulating particles with an electron microscope or an optical microscope, calculating the average value of the particle size of each insulating particle, or using a particle size distribution measuring device. Be done. In observation with an electron microscope or an optical microscope, the particle size of each insulating particle is determined as the particle size in the equivalent circle diameter. When observed with an electron microscope or an optical microscope, the average particle diameter of any 50 insulating particles in the equivalent circle diameter is substantially equal to the average particle diameter in the equivalent diameter of the sphere. In the particle size distribution measuring device, the particle size of each insulating particle is determined as the particle size in the equivalent diameter of a sphere. The average particle size of the insulating particles is preferably calculated using a particle size distribution measuring device. When measuring the particle size of the insulating particles in the conductive particles, for example, the measurement can be performed as follows.

Conductive particles are added to "Technobit 4000" manufactured by Kulzer so as to have a content of 30% by weight and dispersed to prepare an embedded resin body for conducting conductive particle inspection. A cross section of the conductive particles is cut out using an ion milling device (“IM4000” manufactured by Hitachi High-Technologies Corporation) so as to pass near the center of the dispersed conductive particles in the embedded resin body for inspection. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification was set to 50,000 times, 50 conductive particles were randomly selected, and the insulating particles of each conductive particle were observed. do. The particle size of the insulating particles in each conductive particle is measured, and they are arithmetically averaged to obtain the particle size of the insulating particles.

The ratio of the particle size of the conductive particles to the particle size of the insulating particles (particle size of the conductive particles / particle size of the insulating particles) is preferably 4 or more, more preferably 8 or more, and preferably 8. It is 200 or less, more preferably 100 or less. When the above ratio (particle size of conductive particles / particle size of insulating particles) is equal to or more than the above lower limit and less than or equal to the above upper limit, the insulation reliability and conduction reliability are further improved when the electrodes are electrically connected. Can be effectively enhanced.

(Conductive material)
The conductive material according to the present invention includes the above-mentioned conductive particles and a binder resin. The conductive particles are preferably dispersed in the binder resin and used as a conductive material. The conductive material is preferably an anisotropic conductive material. The conductive material is preferably used for electrical connection of electrodes. The conductive material is preferably a circuit connection material.

The binder resin is not particularly limited. As the binder resin, a known insulating resin is used. The binder resin preferably contains a thermoplastic component (thermoplastic compound) or a curable component, and more preferably contains a curable component. Examples of the curable component include a photocurable component and a thermosetting component. The photocurable component preferably contains a photocurable compound and a photopolymerization initiator. The thermosetting component preferably contains a thermosetting compound and a thermosetting agent. Examples of the binder resin include vinyl resins, thermoplastic resins, curable resins, thermoplastic block copolymers, and elastomers. Only one kind of the binder resin may be used, or two or more kinds thereof may be used in combination.

Examples of the vinyl resin include vinyl acetate resin, acrylic resin, styrene resin and the like. Examples of the thermoplastic resin include polyolefin resins, ethylene-vinyl acetate copolymers, and polyamide resins. Examples of the curable resin include epoxy resin, urethane resin, polyimide resin, unsaturated polyester resin and the like. The curable resin may be a room temperature curable resin, a thermosetting resin, a photocurable resin, or a moisture curable resin. The curable resin may be used in combination with a curing agent. Examples of the thermoplastic block copolymer include a styrene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, a hydrogenated additive of a styrene-butadiene-styrene block copolymer, and a styrene-isoprene. -Hydrogen additives of styrene block copolymer and the like can be mentioned. Examples of the elastomer include styrene-butadiene copolymer rubber and acrylonitrile-styrene block copolymer rubber.

In addition to the conductive particles and the binder resin, the conductive material includes, for example, a filler, a bulking agent, a softener, a plasticizer, a polymerization catalyst, a curing catalyst, a colorant, an antioxidant, a heat stabilizer, and a photostabilizer. It may contain various additives such as an agent, an ultraviolet absorber, a lubricant, an antistatic agent and a flame retardant.

As a method for dispersing the conductive particles in the binder resin, a conventionally known dispersion method can be used. Examples of the method for dispersing the conductive particles in the binder resin include the following methods. A method in which the conductive particles are added to the binder resin and then kneaded and dispersed with a planetary mixer or the like. A method in which the conductive particles are uniformly dispersed in water or an organic solvent using a homogenizer or the like, added to the binder resin, and kneaded and dispersed by a planetary mixer or the like. A method in which the binder resin is diluted with water or an organic solvent, the conductive particles are added, and the binder resin is kneaded and dispersed with a planetary mixer or the like.

The viscosity (η25) of the conductive material at 25 ° C. is preferably 30 Pa · s or more, more preferably 50 Pa · s or more, preferably 400 Pa · s or less, and more preferably 300 Pa · s or less. When the viscosity of the conductive material at 25 ° C. is at least the above lower limit and at least the above upper limit, the connection reliability between the electrodes can be further effectively improved. The viscosity (η25) can be appropriately adjusted depending on the type and amount of the compounding component.

The viscosity (η25) can be measured at 25 ° C. and 5 rpm using, for example, an E-type viscometer (“TVE22L” manufactured by Toki Sangyo Co., Ltd.).

The conductive material can be used as a conductive paste, a conductive film, or the like. When the conductive material according to the present invention is a conductive film, a film containing no conductive particles may be laminated on the conductive film containing the conductive particles. The conductive paste is preferably an anisotropic conductive paste. The conductive film is preferably an anisotropic conductive film.

The content of the binder resin in 100% by weight of the conductive material is preferably 10% by weight or more, more preferably 30% by weight or more, still more preferably 50% by weight or more, and particularly preferably 70% by weight or more. Is 99.99% by weight or less, more preferably 99.9% by weight or less. When the content of the binder resin is not less than the above lower limit and not more than the above upper limit, the conductive particles are efficiently arranged between the electrodes, and the connection reliability of the connection target member connected by the conductive material is further improved.

The content of the conductive particles in 100% by weight of the conductive material is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, preferably 80% by weight or less, more preferably 60% by weight. % Or less, more preferably 40% by weight or less, still more preferably 20% by weight or less, and particularly preferably 10% by weight or less. When the content of the conductive particles is not less than the above lower limit and not more than the above upper limit, the connection resistance between the electrodes can be further effectively lowered, and the connection reliability between the electrodes can be further effectively reduced. Can be enhanced.

(Connection structure)
The connection structure according to the present invention includes a first connection target member having a first electrode on the surface, a second connection target member having a second electrode on the surface, the first connection target member, and the above. It includes a connecting portion that connects to the second connection target member. In the connection structure according to the present invention, the connection portion is formed of conductive particles or is formed of a conductive material containing the conductive particles and the binder resin, and the conductive particles are described above. It is a conductive particle, and the first electrode and the second electrode are electrically connected by the conductive particle.

The connection structure includes a step of arranging the conductive particles or the conductive material between the first connection target member and the second connection target member, and a step of conducting a conductive connection by heat-bonding. Can be obtained through. When the conductive particles have the insulating substance, it is preferable that the insulating substance is desorbed from the conductive particles at the time of thermal pressure bonding.

When the above conductive particles are used alone, the connecting portion itself is a conductive particle. That is, the first connection target member and the second connection target member are connected by the conductive particles. The conductive material used to obtain the connection structure is preferably an anisotropic conductive material.

FIG. 6 schematically shows a connection structure using conductive particles according to the first embodiment of the present invention in a front sectional view.

The connection structure 51 shown in FIG. 6 connects a first connection target member 52, a second connection target member 53, and a connection portion 54 connecting the first and second

connection target members

52 and 53. Be prepared. The connecting portion 54 is formed by curing a conductive material containing the conductive particles 1. In FIG. 6, the conductive particles 1 are shown schematicly for convenience of illustration. Instead of the conductive particles 1, other conductive particles such as conductive particles 1A, 1B, 1C, and 1D may be used.

The manufacturing method of the above connection structure is not particularly limited. As an example of a method for manufacturing a connection structure, the conductive material is arranged between a first connection target member and a second connection target member, and after obtaining a laminate, the laminate is heated and pressurized. The method and the like can be mentioned. The pressure at the time of pressurization is preferably 40 MPa or more, more preferably 60 MPa or more, preferably 90 MPa or less, and more preferably 70 MPa or less. The temperature at the time of heating is preferably 80 ° C. or higher, more preferably 100 ° C. or higher, preferably 140 ° C. or lower, and more preferably 120 ° C. or lower.

Since the above-mentioned conductive particles are used in the connection structure according to the present invention, the conductive particles are satisfactorily compressed during the above heating and pressurization, and are satisfactorily compressed on the surface of the conductive particles (for example, a conductive portion). Not only the conduction path is formed, but also the conduction path is satisfactorily formed inside the conductive particles. As a result, the effects of the above-mentioned 1) -3) of the present invention can be exhibited, and the risk of electrode breakage can be suppressed.

The first connection target member and the second connection target member are not particularly limited. Specific examples of the first connection target member and the second connection target member include electronic components such as semiconductor chips, semiconductor packages, LED chips, LED packages, capacitors and diodes, resin films, printed circuit boards, and flexible devices. Examples thereof include electronic components such as printed circuit boards, flexible flat cables, rigid flexible boards, glass epoxy boards, and circuit boards such as glass boards. The first connection target member and the second connection target member are preferably electronic components.

Examples of the electrodes provided on the connection target member include metal electrodes such as gold electrodes, nickel electrodes, tin electrodes, aluminum electrodes, copper electrodes, molybdenum electrodes, silver electrodes, SUS electrodes, and tungsten electrodes. When the member to be connected is a flexible printed substrate, the electrodes are preferably gold electrodes, nickel electrodes, tin electrodes, silver electrodes or copper electrodes. When the connection target member is a glass substrate, the electrode is preferably an aluminum electrode, a copper electrode, a molybdenum electrode, a silver electrode, or a tungsten electrode. When the electrode is an aluminum electrode, it may be an electrode formed only of aluminum, or an electrode in which an aluminum layer is laminated on the surface of a metal oxide layer. Examples of the material of the metal oxide layer include indium oxide doped with a trivalent metal element and zinc oxide doped with a trivalent metal element. Examples of the trivalent metal element include Sn, Al and Ga.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The present invention is not limited to the following examples.

(Example 1)
(1) Preparation of Base Particles for Metal Particle Formation Polystyrene particles having an average particle diameter of 0.9 μm were prepared as seed particles. A mixed solution was prepared by mixing 3.9 parts by weight of the polystyrene particles, 500 parts by weight of ion-exchanged water, and 120 parts by weight of a 5% by weight polyvinyl alcohol aqueous solution. After the above mixed solution was dispersed by ultrasonic waves, it was placed in a separable flask and stirred uniformly.

Next, 150 parts by weight of divinylbenzene (monomer component), 2 parts by weight of 2,2'-azobis (methyl isobutyrate) ("V-601" manufactured by Wako Pure Chemical Industries, Ltd.), and benzoyl peroxide (NOF Corporation). 2 parts by weight of "NOF BW" manufactured by Japan, Ltd. was mixed. Further, 9 parts by weight of triethanolamine lauryl sulfate, 50 parts by weight of toluene (solvent), and 1100 parts by weight of ion-exchanged water were added to prepare an emulsion.

The emulsion was added to the mixture in a separable flask in several portions, and the mixture was stirred for 12 hours to allow the seed particles to absorb the monomer to obtain a suspension containing the seed particles in which the monomer was swollen. ..

Then, 490 parts by weight of a 5 wt% polyvinyl alcohol aqueous solution was added, heating was started, and the mixture was reacted at 85 ° C. for 9 hours to obtain base particles for forming metal particles having a particle size of 4.0 μm and a CV value of 3.0%. rice field.

(2) Preparation of Metal Particles (Conductive Particles) The obtained base particles for forming metal particles are washed and dried, and then the base particles 10 are added to 1000 parts by weight of an alkaline solution containing 5% by weight of a palladium catalyst solution. After dispersing the parts by weight using an ultrasonic disperser, the base particles for forming metal particles were taken out by filtering the solution. Next, the base particles for forming metal particles were added to 100 parts by weight of a 1 wt% solution of dimethylamine borane to activate the surface of the substrate particles. After thoroughly washing the surface-activated metal particle-forming substrate particles with water, the particles were added to 500 parts by weight of distilled water and dispersed to obtain a dispersion liquid.

Further, a nickel plating solution (pH 8.5) containing nickel sulfate 0.35 mol / L, dimethylamine borane 1.38 mol / L and sodium citrate 0.5 mol / L was prepared.

While stirring the obtained dispersion at 60 ° C., 150 parts by weight of the nickel plating solution was gradually added dropwise to the dispersion to perform electroless nickel plating. Then, the dispersion liquid was filtered to take out the particles, washed with water, and dried to obtain particles in which nickel was precipitated inside the base particles for forming metal particles.

Further, the obtained particles on which the nickel was precipitated were heated at 400 ° C. for 12 hours under nitrogen flow and then washed with 0.1 N nitric acid to obtain metal particles having a porous structure.

(3) Preparation of conductive material (anisotropic conductive paste) 7 parts by weight of the obtained metal particles (conductive particles), 25 parts by weight of bisphenol A type phenoxy resin, 4 parts by weight of fluorene type epoxy resin, and phenol novolac. A conductive material (anisotropic conductive paste) was obtained by blending 30 parts by weight of the type epoxy resin and SI-60L (manufactured by Sanshin Chemical Industry Co., Ltd.), defoaming and stirring for 3 minutes.

(4) Preparation of Connection Structure A transparent glass substrate having an IZO electrode pattern (first electrode, Vickers hardness of metal on the electrode surface of 100 Hv) having an L / S of 10 μm / 10 μm formed on the upper surface (first connection target). Members) were prepared. Further, a semiconductor chip (second connection target member) having an Au electrode pattern (second electrode, Vickers hardness of metal on the electrode surface 50 Hv) having an L / S of 10 μm / 10 μm formed on the lower surface was prepared. The obtained anisotropic conductive paste was coated on the transparent glass substrate so as to have a thickness of 30 μm to form an anisotropic conductive paste layer. Next, the semiconductor chips were laminated on the anisotropic conductive paste layer so that the electrodes face each other. After that, while adjusting the temperature of the head so that the temperature of the anisotropic conductive paste layer becomes 100 ° C., the pressure heating head is placed on the upper surface of the semiconductor chip, and a pressure of 55 MPa is applied to form the anisotropic conductive paste layer. It was cured at 100 ° C. to obtain a connecting structure.

(Example 2)
(1) Preparation of Metal Particles (Base Material Particles) The metal particles (conductive particles) obtained in Example 1 were used as the metal particles as the base material particles in Example 2.

(2) Preparation of Conductive Particles A nickel plating solution (pH 8.5) containing nickel sulfate 0.35 mol / L, dimethylamine borane 1.38 mol / L and sodium citrate 0.5 mol / L was prepared.

The above metal particles were dispersed in pure water to obtain a dispersion liquid. While stirring the obtained dispersion at 60 ° C., 50 parts by weight of the nickel plating solution was gradually added dropwise to the dispersion to perform electroless nickel plating. Then, by filtering the dispersion liquid, the particles are taken out, washed with water, and dried to form a nickel-boron conductive layer on the surface of the metal particles (base particle), and the conductive particles have a conductive portion on the surface. Got

(3) Preparation of Conductive Material (Anisically Conductive Paste) and Connection Structure A conductive material and a connection structure were obtained in the same manner as in Example 1 except that the obtained conductive particles were used.

(Example 3)
Conductive particles, a conductive material, and a connecting structure were obtained in the same manner as in Example 2 except that the amount of the nickel plating solution used was changed from 50 parts by weight to 100 parts by weight.

(Example 4)
A gold plating solution was prepared by adding 5 g of potassium gold cyanide to 500 g of a solution containing 10 g / L sodium ethylenediamine 4 acetate and 10 g / L sodium citrate.

10 parts by weight of the conductive particles having the nickel-boron conductive layer obtained in Example 3 were placed in 500 parts by weight of the gold plating solution and immersed at 70 ° C. for 30 minutes to perform electroless gold plating. Then, by filtering the liquid, the particles are taken out, washed with water, and dried to form a nickel-boron-gold conductive layer on the surface of the metal particles (base particles), and the conductive portion has a conductive portion on the surface. Obtained particles. A conductive material and a connecting structure were obtained in the same manner as in Example 1 except that the obtained conductive particles were used.

(Example 5)
A palladium plating solution containing 10 g / L ethylenediamine, 3.0 g / L palladium sulfate, and 5.0 g / L sodium formate was prepared.

A dispersion liquid was obtained by adding 10 parts by weight of the conductive particles having the nickel-boron conductive layer obtained in Example 3 to 200 parts by weight of distilled water and dispersing them. After heating the obtained dispersion to 70 ° C., 700 parts by weight of the palladium plating solution was added dropwise to the dispersion over 10 minutes to perform electroless palladium plating. Then, by filtering the dispersion liquid, the particles are taken out, washed with water, and dried to form a nickel-boron-palladium conductive layer on the surface of the metal particles (base particle), and the conductive portion has a conductive portion on the surface. Sex particles were obtained. A conductive material and a connecting structure were obtained in the same manner as in Example 1 except that the obtained conductive particles were used.

(Example 6)
Conductive particles, a conductive material, and a connecting structure were obtained in the same manner as in Example 2 except that the amount of the nickel plating solution used was changed from 50 parts by weight to 200 parts by weight.

(Example 7)
Electroless gold plating was performed under the conditions described in Example 4 using the conductive particles having the nickel-boron conductive layer obtained in Example 6. In this way, conductive particles having a nickel-boron-gold conductive layer were obtained. A conductive material and a connecting structure were obtained in the same manner as in Example 1 except that the conductive particles were used.

(Example 8)
Electroless palladium plating was performed under the conditions described in Example 5 using the conductive particles having the nickel-boron conductive layer obtained in Example 6. In this way, conductive particles having a nickel-boron-palladium conductive layer were obtained. A conductive material and a connecting structure were obtained in the same manner as in Example 1 except that the conductive particles were used.

(Example 9)
(1) Preparation of metal particles (base particles) to which a core substance is attached In "(2) Preparation of metal particles (conductive particles)" of Example 1, a nickel particle slurry (average particle diameter 100 nm) is contained in a dispersion liquid. By adding 1 g over 3 minutes, metal particles (base particle) to which the core substance was attached and having a porous structure were obtained.

(2) Preparation of Conductive Particles to which Insulating Particles Are Not Adhered Conductive particles (insulating property) in the same manner as in Example 2 except that the amount of the nickel plating solution used was changed from 50 parts by weight to 300 parts by weight. Conductive particles to which no particles were attached) were obtained.

(3) Preparation of Insulating Particles After putting the following monomer composition in a 1000 mL separable flask equipped with a four-mouth separable cover, a stirring blade, a three-way cock, a cooling tube and a temperature probe, the following monomer composition Distilled water was added so that the solid content was 10% by weight, the mixture was stirred at 200 rpm, and polymerization was carried out at 60 ° C. for 24 hours under a nitrogen atmosphere. The monomer composition comprises 360 mmol of methyl methacrylate, 45 mmol of glycidyl methacrylate, 20 mmol of parastyryldiethylphosphine, 13 mmol of ethylene glycol dimethacrylate, 0.5 mmol of polyvinylpyrrolidone, and 2,2'-azobis {2- [N- (2). -Carboxyethyl) amidino] propane} 1 mmol. After completion of the reaction, the reaction was freeze-dried to obtain insulating particles (particle size 360 nm) having a phosphorus atom derived from parastilyl diethylphosphine on the surface.

(4) Preparation of Conductive Particles with Insulating Particles The obtained insulating particles were dispersed in distilled water under ultrasonic irradiation to obtain a 10 wt% aqueous dispersion of the insulating particles. 10 g of the obtained conductive particles to which the insulating particles were not attached were dispersed in 500 mL of distilled water, 1 g of a 10 wt% aqueous dispersion of the insulating particles was added, and the mixture was stirred at room temperature for 8 hours. After filtering with a 3 μm mesh filter, the mixture was further washed with methanol and dried to obtain conductive particles with insulating particles.

(5) Preparation of Conductive Material (Anisically Conductive Paste) and Connection Structure The conductive material and connection structure are prepared in the same manner as in Example 1 except that the obtained conductive particles with insulating particles are used. Obtained.

(Example 10)
Conductive particles, a conductive material, and a connecting structure were obtained in the same manner as in Example 9 except that electroless gold plating was performed after electroless nickel plating.

(Example 11)
Conductive particles, a conductive material, and a connecting structure were obtained in the same manner as in Example 9 except that electroless nickel plating was performed and then electroless palladium plating was performed.

(Example 12)
150 parts by weight of divinylbenzene (monomer component), 2 parts by weight of 2,2'-azobis (methyl isobutyrate) ("V-601" manufactured by Wako Pure Chemical Industries, Ltd.), and benzoyl peroxide ("Niper" manufactured by NOF Corporation). BW ") 2 parts by weight were mixed. Further, 9 parts by weight of triethanolamine lauryl sulfate, 50 parts by weight of toluene (solvent), and 1100 parts by weight of ion-exchanged water were added to prepare an emulsion. Then, emulsification was performed using a Silicona Porus Glass (SPG) membrane (pore average diameter of about 2 μm).

After that, 490 parts by weight of a 5 wt% polyvinyl alcohol aqueous solution was added, heating was started, and the mixture was reacted at 85 ° C. for 9 hours to carry out polymerization. After washing the entire amount of the polymerized particles with water by centrifugation, the obtained base particles are classified to obtain metal particle-forming base particles having an average particle diameter of 4.0 μm and a CV value of 13.2%. Obtained. Conductive particles, a conductive material, and a connecting structure were obtained in the same manner as in Example 1 except that the obtained base particles for forming metal particles were used.

(Example 13)
By further classifying the metal particle-forming base particles obtained in Example 12, metal particle-forming base particles having an average particle diameter of 4.0 μm and a CV value of 8.3% were obtained. Conductive particles, a conductive material, and a connecting structure were obtained in the same manner as in Example 1 except that the obtained base particles for forming metal particles were used.

(Example 14)
Conductive particles with insulating particles, a conductive material, and a connecting structure were obtained in the same manner as in Example 9 except that the base particles for forming metal particles obtained in Example 12 were used.

(Example 15)
Conductive particles with insulating particles, a conductive material, and a connecting structure were obtained in the same manner as in Example 14, except that electroless nickel plating was performed and then electroless gold plating was performed.

(Example 16)
Conductive particles with insulating particles, a conductive material, and a connecting structure were obtained in the same manner as in Example 14, except that electroless nickel plating was performed and then electroless palladium plating was performed.

(Comparative Example 1)
(1) Preparation of Resin Particles (Base Particles) Polystyrene particles having an average particle diameter of 0.93 μm were prepared as seed particles. A mixed solution was prepared by mixing 3.9 parts by weight of the polystyrene particles, 500 parts by weight of ion-exchanged water, and 120 parts by weight of a 5% by weight aqueous solution of polyvinyl alcohol. After the above mixed solution was dispersed by ultrasonic waves, it was placed in a separable flask and stirred uniformly.

Next, 2 parts by weight of 2,2'-azobis (methyl isobutyrate) ("V-601" manufactured by Wako Pure Chemical Industries, Ltd.) and 2 parts by weight of benzoyl peroxide ("Niper BW" manufactured by Nichiyu Co., Ltd.) were added. After mixing, 150 parts by weight of divinylbenzene, 9 parts by weight of triethanolamine lauryl sulfate, 30 parts by weight of ethanol, and 1100 parts by weight of ion-exchanged water were added to prepare an emulsion.

Then, 490 parts by weight of a 5 wt% aqueous solution of polyvinyl alcohol was added, heating was started, and the mixture was reacted at 85 ° C. for 9 hours to obtain resin particles. The obtained resin particles have a non-porous structure (solid structure).

(2) Preparation of Conductive Particles Electroless nickel is produced in the same manner as in "(2) Preparation of metal particles (conductive particles)" of Example 1 except that the obtained resin particles are used. Plating was performed. The particles subjected to this electroless nickel plating were used as conductive particles.

(Comparative Example 2)
(1) Preparation of Metal Particles 10 parts by weight of nickel particles (solid structure, average particle diameter 4.0 μm, CV value of particle diameter 30%) were prepared. The nickel particles were electroless gold plated in the same manner as in Example 4. In this way, metal particles having a non-porous structure (solid structure) were obtained.

(2) Preparation of Conductive Material (Anisically Conductive Paste) and Connection Structure A conductive material and a connection structure were obtained in the same manner as in Example 1 except that the obtained metal particles were used.

(evaluation)
(1) Specific Surface Area of Conductive Particles With respect to the obtained conductive particles, the adsorption isotherm of nitrogen was measured using "NOVA4200e" manufactured by Cantachrome Instruments. From the measurement results, the specific surface area of the conductive particles was calculated according to the BET method.

(2) Specific Density of Conductive Particles The specific gravity of the obtained conductive particles was measured using a true hydrometer (“Acupic II” manufactured by Shimadzu Corporation).

(3) Particle size and coefficient of variation of conductive particles With respect to the obtained conductive particles, the particle size of about 100,000 resin particles was measured using a particle size distribution measuring device (“Multisizer4” manufactured by Beckman Coulter). The average value was calculated. Further, from the measurement result of the particle size of the conductive particles, the coefficient of variation (CV value) of the particle size of the conductive particles was calculated from the following formula.

CV value (%) = (ρ / Dn) × 100
ρ: Standard deviation of the particle size of the coefficient of variation Dn: Average value of the particle size of the coefficient of variation

(4) Resin content in 100% by weight of metal particles The content of metal in metal particles (% by weight) was measured by ICP emission spectrometry. The resin content in 100% by weight of the metal particles was determined by the following formula.

Resin content (% by weight) = 100-Metal content in metal particles (% by weight)

(5) Thickness of Conductive Part Addition to "Technobit 4000" manufactured by Kulzer so that the content of the conductive particles of Examples 2 to 11, 14 to 16 and Comparative Examples 1 and 2 is 30% by weight. It was dispersed to prepare an embedded resin body for inspection. A cross section of the conductive particles was cut out using an ion milling device (“IM4000” manufactured by Hitachi High-Technologies Corporation) so as to pass near the center of the conductive particles dispersed in the embedded resin body for inspection.

Then, using a field emission transmission electron microscope (FE-TEM) (“JEM-ARM200F” manufactured by JEOL Ltd.), the image magnification was set to 50,000 times, and 50 conductive particles were randomly selected. The conductive part of each conductive particle was observed. The thickness of the conductive portion of each conductive particle was measured, and the thickness was calculated and averaged to obtain the thickness of the conductive portion.

(6) Connection resistance value (between the upper and lower electrodes)
The connection resistance between the upper and lower electrodes of the obtained 20 connection structures was measured by the 4-terminal method, respectively. The average value of the connection resistance was calculated. From the relationship of voltage = current x resistance, the connection resistance can be obtained by measuring the voltage when a constant current is passed.

(7) Withstand current characteristics The average current value when the voltage value became 20 V or more when the current value of the connected structure was changed from 0.01 A to 1 A was measured.

[Criteria for determining withstand current characteristics]
○○: Average current value when the voltage value is 20V or more is 0.5A or more ○: Average current value when the voltage value is 20V or more is 0.1A or more and less than 0.5A ×: Voltage value is 20V or more The average current value when becomes less than 0.1A

(8) Insulation reliability (between adjacent electrodes in the lateral direction)
In the 20 connection structures obtained in the above (6) Evaluation of connection resistance, the presence or absence of leakage between adjacent electrodes was evaluated by measuring the resistance value with a tester. Insulation reliability was evaluated according to the following criteria.

[Criteria for insulation reliability]
○: The number of resistance 10 ⁸ Omega more connecting structure 15 or more ×: number of resistance 10 ⁸ Omega more connection structure is less than 15

The results are shown in Tables 1 to 3 below.

1,1A, 1B, 1C, 1D ... Conductive particles 1Ba ... Protrusions 2 ... Metal particles 3,3A, 3B, 3C ... Conductive parts 3Ba, 3Ca ... Protrusions 4 ... Core material 5 ... Insulating material 11 ... Conductive particles 21 ... Conductive particles 22 ... Conductive part 31C ... First conductive part 32C ... Second conductive part 31Ca, 32Ca ... Protrusions 51 ... Connection structure 52 ... First connection target member 52a ... First electrode 53 ... Second Connection target member 53a ... Second electrode 54 ... Connection part

Claims

With metal particles having a porous structure,
A conductive particle having the following configuration A or the following configuration B.
Configuration A: The specific surface area of the conductive particles is 10 m 2 / g or more.
Configuration B: The specific surface area of the conductive particles is less than 10 m 2 / g, and the specific gravity is 1 g / cm 3 or more and 8 g / cm 3 or less.
The conductive particle according to claim 1, further comprising the configuration A.
The conductive particle according to claim 1, further comprising the configuration B.
The conductive particle according to any one of claims 1 to 3, further comprising a conductive portion arranged on the outer surface of the metal particle.
When the configuration A is provided, the thickness of the conductive portion is less than 50 nm.
The conductive particle according to claim 4, wherein the conductive portion has a thickness of 50 nm or more when the configuration B is provided.
The conductive particles according to claim 4 or 5, further comprising an insulating substance arranged on the outer surface of the conductive portion.
The conductive particle according to any one of claims 4 to 6, which has protrusions on the outer surface of the conductive portion.
The conductive particle according to any one of claims 1 to 7, wherein the coefficient of variation of the particle size of the conductive particle is 20% or less.
The metal particles do not contain or contain resin,
The conductive particle according to any one of claims 1 to 8, wherein when the metal particles contain a resin, the content of the resin is 10% by weight or less in 100% by weight of the metal particles.
The conductive particle according to any one of claims 1 to 9, wherein the conductive particle has a particle size of 0.1 μm or more and 1000 μm or less.
The conductive particle according to any one of claims 1 to 10, wherein the metal constituting the metal particle contains nickel.
The conductive particles according to any one of claims 1 to 11.
Conductive material, including binder resin.
A first connection target member having a first electrode on its surface,
A second connection target member having a second electrode on the surface,
The first connection target member and the connection portion connecting the second connection target member are provided.
The connecting portion is formed of conductive particles, or is formed of a conductive material containing the conductive particles and a binder resin.
The conductive particles according to any one of claims 1 to 11, wherein the conductive particles are the conductive particles.
A connection structure in which the first electrode and the second electrode are electrically connected by the conductive particles.