WO2013094636A1

WO2013094636A1 - Conductive particles, conductive material, and connection structure

Info

Publication number: WO2013094636A1
Application number: PCT/JP2012/082910
Authority: WO
Inventors: 敬三西岡
Original assignee: 積水化学工業株式会社
Priority date: 2011-12-21
Filing date: 2012-12-19
Publication date: 2013-06-27
Also published as: KR101942602B1; JPWO2013094636A1; CN108806824B; KR20140106384A; JP6247371B2; CN108806824A; JP6049461B2; TW201333980A; JP2017084794A; TWI615858B; CN103748636A

Abstract

Provided are conductive particles which are capable of reducing connection resistance between electrodes. Conductive particles (1) according to the present invention are each provided with: a base particle (2); a conductive layer (3) covering the base particle (2); and cores (4) of a substance embedded in the conductive layer (3). The conductive layer (3) has protrusions (3a) on the outside surface thereof. The cores (4) of a substance are disposed inside the protrusions (3a) on the conductive layer (3). Distances separate the surface of the base particle (2) from the surfaces of the cores (4) of a substance, the average distance therebetween being over 5nm.

Description

Conductive particles, conductive materials, and connection structures

The present invention relates to conductive particles in which a conductive layer is disposed on the surface of base particles, and more particularly to conductive particles that can be used for electrical connection between electrodes, for example. The present invention also relates to a conductive material and a connection structure using the 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 a binder resin.

The anisotropic conductive material is used for connection between an IC chip and a flexible printed circuit board, connection between an IC chip and a circuit board having an ITO electrode, and the like. For example, after disposing an anisotropic conductive material between the electrode of the IC chip and the electrode of the circuit board, these electrodes can be electrically connected by heating and pressing.

As an example of the conductive particles, the following Patent Document 1 discloses a conductive material in which a nickel conductive layer or a nickel alloy conductive layer is formed on the surface of spherical base particles having an average particle diameter of 1 to 20 μm by an electroless plating method. Sex particles are disclosed. The conductive particles have minute protrusions of 0.05 to 4 μm on the outermost layer of the conductive layer. The conductive layer and the protrusion are substantially continuously connected.

In Patent Document 2 below, a plastic core, a polymer electrolyte layer covering the plastic core, metal particles adsorbed on the plastic core through the polymer electrolyte layer, and the metal particles are covered. The electroconductive particle provided with the electroless metal plating layer formed in the circumference | surroundings of the said plastic core is disclosed.

The following Patent Document 3 discloses conductive particles in which a multilayer conductive layer of a metal plating film layer containing nickel and phosphorus and a gold layer is formed on the surface of a base material particle. In the conductive particles, a core substance is disposed on the surface of the base particle, and the core substance is covered with a conductive layer. The conductive layer is raised by the core material, and protrusions are formed on the surface of the conductive layer.

JP 2000-243132 A JP 2011-108446 A JP 2006-228475 A

Patent Documents 1 to 3 described above disclose conductive particles having protrusions on the outer surface of the conductive layer. In many cases, an oxide film is formed on the surfaces of the electrodes connected by the conductive particles and the conductive layer of the conductive particles. The protrusion of the conductive layer is formed so as to contact the conductive layer and the electrode by eliminating the oxide film on the surface of the electrode and the conductive particle when the electrodes are pressure-bonded via the conductive particle. .

However, when the electrodes are connected using conventional conductive particles having protrusions on the outer surface of the conductive layer, the oxide film on the surfaces of the electrodes and the conductive particles cannot be sufficiently eliminated, and the connection resistance is high. May be.

An object of the present invention is to provide conductive particles capable of reducing the connection resistance between electrodes when a connection structure is obtained by connecting electrodes, and a conductive material and connection structure using the conductive particles. Is to provide.

According to a wide aspect of the present invention, the method includes a base particle, a conductive layer covering the base particle, and a plurality of core substances embedded in the conductive layer, wherein the conductive layer is outside. A plurality of protrusions on the surface, the core substance is disposed inside the protrusions of the conductive layer, the conductive layer is disposed between the base material particles and the core substance, and the base Conductive particles are provided in which the surface of the material particles and the surface of the core substance are separated from each other, and the average distance between the surface of the base material particles and the surface of the core substance exceeds 5 nm.

In a specific aspect of the conductive particle according to the present invention, an average distance between the surface of the base material particle and the surface of the core substance is more than 5 nm and 800 nm or less.

In a specific aspect of the conductive particles according to the present invention, the total number of the core materials is 100%, and the distance between the surface of the base material particles and the surface of the core material is more than 5 nm. The ratio is more than 80% and not more than 100%.

In a specific aspect of the conductive particle according to the present invention, the metal element contained most in the core material and the metal element contained most in the conductive layer are the same.

In another specific aspect of the conductive particle according to the present invention, the conductive layer covers the first conductive layer covering the base particle, the first conductive layer, and the core substance. The core material is disposed on the surface of the first conductive layer and embedded in the second conductive layer, and the second conductive layer. Has a plurality of protrusions on the outer surface, the core substance is disposed inside the protrusions of the second conductive layer, and the first substance is interposed between the base particle and the core substance. A conductive layer is disposed.

In another specific aspect of the conductive particle according to the present invention, the metal element contained most in the core material and the metal element contained most in the second conductive layer are the same.

In yet another specific aspect of the conductive particles according to the present invention, the conductive layer is a single conductive layer.

In another specific aspect of the conductive particle according to the present invention, the core substance is a metal particle.

In another specific aspect of the conductive particle according to the present invention, an insulating material attached to the surface of the conductive layer is further provided.

The conductive material according to the present invention includes the above-described conductive particles and a binder resin.

The connection structure according to the present invention includes a first connection target member, a second connection target member, and a connection portion connecting the first and second connection target members, and the connection The part is formed of the above-described conductive particles, or is formed of a conductive material containing the conductive particles and a binder resin.

The conductive particle according to the present invention includes a base particle, a conductive layer covering the base particle, and a plurality of core substances embedded in the conductive layer. Protrusions on the outer surface, the core substance is disposed inside the protrusions of the conductive layer, the conductive layer is disposed between the substrate particles and the core substance, and the base The surface of the material particles and the surface of the core substance are separated from each other, and the average distance between the surface of the base material particles and the surface of the core substance exceeds 5 nm. When used for connection between electrodes, the connection resistance between the electrodes can be lowered.

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

Hereinafter, the details of the present invention will be described.

The conductive particles according to the present invention include base particles, a conductive layer covering the base particles, and a plurality of core substances embedded in the conductive layer. The conductive layer has a plurality of protrusions on the outer surface. The core substance is disposed inside the protrusion of the conductive layer. The conductive layer is disposed between the base particle and the core substance. A partial region of the conductive layer is disposed between the base particle and the core substance. The surface of the base particle and the surface of the core substance are separated from each other. The average distance between the surface of the substrate particle and the surface of the core substance is more than 5 nm.

An oxide film is often formed on the surface of the electrode connected by the conductive particles. Furthermore, an oxide film is often formed on the outer surface of the conductive layer. When the conductive layer has a plurality of protrusions on the outer surface, the oxide film is eliminated by the protrusions by placing the conductive particles between the electrodes and then pressing them. For this reason, an electrode and electroconductive particle can be made to contact and the connection resistance between electrodes can be made low.

Furthermore, in the conductive particles according to the present invention, the conductive layer is disposed between the base particle and the core substance, and the surface of the base particle and the surface of the core substance are spaced apart from each other. In addition, since the average distance between the surface of the base material particle and the surface of the core material exceeds 5 nm, the core material is difficult to push the base material particle when the conductive particles are compressed between the electrodes. A part of the region is difficult to sink into the base particle. In particular, even if the base particles are relatively soft resin particles, the core substance is difficult to push the base particles, and a part of the core substance is difficult to sink into the base particles. For this reason, the protrusions of the conductive layer are strongly pressed against the electrodes during pressure bonding between the electrodes. As a result, the oxide film is effectively eliminated by the protrusions. For this reason, an electrode and electroconductive particle can be made to contact effectively and the connection resistance between electrodes can be made low effectively.

In addition, since the conductive particles according to the present invention have the above-described configuration, when the conductive particles are compressed to connect the electrodes, it is possible to form an appropriate indentation on the electrodes. The indentation formed on the electrode is a concave portion of the electrode formed by pressing the electrode with conductive particles. Furthermore, when a conductive material (such as anisotropic conductive material) in which conductive particles are dispersed in a binder resin is used for pressure bonding between electrodes, the binder resin between the conductive layer and the electrode is effectively eliminated. it can. The connection resistance between the electrodes can also be lowered by effectively eliminating the binder resin. In addition, when conductive particles including an insulating material are used, the insulating material between the conductive layer and the electrode can be effectively eliminated by the protrusions, so that the conduction reliability between the electrodes is effectively increased. Can do.

From the viewpoint of further effectively eliminating the oxide film on the surface of the electrode and the conductive particles and further improving the conduction reliability between the electrodes, the average between the surface of the base particle and the surface of the core substance The distance is preferably 5 nm or more, more preferably 10 nm or more. The upper limit of the average distance between the surface of the substrate particle and the surface of the core substance is not particularly limited, and is appropriately determined in consideration of the thickness of the conductive layer. The average distance between the surface of the base material particle and the surface of the core substance may be 800 nm or less, or 100 nm or less. The average distance between the surface of the base material particle and the surface of the core substance is preferably 30 nm or less, more preferably 20 nm or less. The average distance between the surface of the base material particle and the surface of the core substance may be 9/10 or less, 1/2 or less, or 1/3 or less of the thickness of the conductive layer. There may be.

From the viewpoint of more effectively eliminating the oxide film on the surface of the electrode and the conductive particles and further improving the conduction reliability between the electrodes, the surface of the base particle in the total number of 100% of the core substance The ratio of the number of core materials whose distance from the surface of the core material exceeds 5 nm is preferably 50% or more, more preferably more than 80% and 100% or less. In all of the core materials, the distance between the surface of the base particle and the surface of the core material may exceed 5 nm.

The average distance between the surface of the base particle and the surface of the core substance is measured after measuring the distance (the shortest distance between the gaps) between the surface of the base particle and each surface of the plurality of core substances. It is calculated by averaging the obtained values. When the conductive particles include five core materials A to E embedded in the conductive layer, the distance between the surface of the base material particle and the surface of the core material A, the surface of the base material particle and the core material B The distance between the surface, the distance between the surface of the base material particle and the surface of the core material C, the distance between the surface of the base material particle and the surface of the core material D, the surface of the base material particle and the surface of the core material E Is calculated by averaging the five measured values. In addition, when the number of core materials is 10 or more, it is preferable to measure the distance between the surface of the base material particles and each surface of all the core materials. The distance from each surface of the core material may be measured, and the average distance may be calculated from the 10 measured values.

The distance between the surface of the base material particle and the surface of the core substance was obtained by photographing a plurality of cross-sections of the conductive particles to obtain an image, and creating a stereoscopic image from the obtained image. By using a stereoscopic image, it can be measured accurately. The section can be imaged using a focused ion beam-scanning electron microscope (FIBSEM) or the like. For example, a thin film slice of conductive particles is prepared using a focused ion beam, and the cross section is observed with a scanning electron microscope. A three-dimensional image of the particles can be obtained by repeating the operation several hundred times and analyzing the image.

The conductive layer has protrusions on the outer surface. There are a plurality of protrusions. An oxide film is often formed on the surface of the conductive layer and the surface of the electrode connected by the conductive particles. By using conductive particles having protrusions on the outer surface of the conductive layer, the oxide particles are effectively eliminated by the protrusions by placing the conductive particles between the electrodes and pressing them. For this reason, an electrode and the conductive layer of electroconductive particle can be contacted still more reliably, and the connection resistance between electrodes can be made low. Furthermore, when the conductive particles are provided with an insulating material on the surface, or when the conductive particles are dispersed in a binder resin and used as a conductive material, the protrusions of the conductive particles cause a gap between the conductive particles and the electrode. Insulating substances or binder resins can be effectively eliminated. For this reason, the conduction | electrical_connection reliability between electrodes can be improved.

The average height of the plurality of protrusions is preferably 0.001 μm or more, more preferably 0.05 μm or more, preferably 0.9 μm or less, more preferably 0.2 μm or less. When the average height of the protrusions is not less than the above lower limit and not more than the above upper limit, the connection resistance between the electrodes can be effectively lowered.

Hereinafter, details of the conductive particles, the conductive material, and the connection structure will be described.

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

1 includes a base particle 2, a conductive layer 3, a plurality of core materials 4, and an insulating material 5. The conductive particles 1 shown in FIG. The conductive layer 3 is disposed on the surface of the base particle 2. In the conductive particles 1, a single conductive layer 3 is formed. The conductive layer 3 covers the base particle 2. The conductive layer 3 has a plurality of protrusions 3a on the outer surface. The plurality of core substances 4 are arranged on the surface of the base particle 2 and are embedded in the conductive layer 3. The core substance 4 is disposed inside the protrusion 3a. One core material 4 is arranged inside one protrusion 3a. The outer surface of the conductive layer 3 is raised by the plurality of core materials 4, and a plurality of protrusions 3 a are formed.

The conductive layer 3 is disposed between the surface of the base particle 2 and the surface of the core substance 4. The surface of the base particle 2 and the surface of the core material 4 are separated from each other. The core substance 4 is not in contact with the base particle 2. In the electroconductive particle 1, the average distance between the surface of the base material particle 2 and the surface of the core substance 4 exceeds 5 nm. For this reason, between the surface of the base material particle 2 and the surface of the core substance 4, the conductive layer 3 part (conductive layer part 3b) of sufficient thickness is arrange | positioned. The distance between the surface of the base material particle 2 and the surface of the core material 4 is the thickness of the conductive layer portion 3 b disposed between the surface of the base material particle 2 and the surface of the core material 4.

The insulating material 5 is disposed on the surface of the conductive layer 3. The insulating material 5 is an insulating particle. The insulating substance 5 is made of an insulating material. The conductive particles do not necessarily include an insulating substance. In addition, the conductive particles may include an insulating layer that covers the outer surface of the conductive layer instead of the insulating particles as an insulating substance.

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

2 includes a base particle 2, a conductive layer 12, a plurality of core substances 4, and an insulating substance 5. The conductive particles 11 shown in FIG. The conductive layer 12 is disposed on the surface of the base particle 2. The conductive layer 12 covers the base particle 2. The conductive layer 12 has a plurality of protrusions 12a on the outer surface.

In the conductive particles 11, a multilayer conductive layer 12 is formed. The conductive layer 12 includes a first conductive layer 16 and a second conductive layer 17. The first conductive layer 16 is disposed on the surface of the base particle 2. The first conductive layer 16 covers the base particle 2. The first conductive layer 16 is a single layer. The first conductive layer may be a multilayer.

The core material 4 is disposed on the first conductive layer 16. The core material 4 is embedded in the conductive layer 12 and the second conductive layer 17. A first conductive layer 16 is disposed between the base particle 2 and the core substance 4. By disposing the first conductive layer 16 between the base material particle 2 and the core material 4, the surface of the base material particle 2 and the surface of the core material 4 are separated from each other. The average distance between the surface of the base particle 2 and the surface of the core material 4 exceeds 5 nm. In the conductive particle 11, the distance between the surface of the base material particle 2 and the surface of the core material 4 is such that the conductive layer portion 12 b disposed between the surface of the base material particle 2 and the surface of the core material 4 and It is the thickness of the 1st conductive layer 16 (1st conductive layer 16 part).

The second conductive layer 17 is formed separately from the first conductive layer 16. The second conductive layer 17 is formed on the surface of the first conductive layer 16 after the first conductive layer 16 is formed. The second conductive layer 17 is disposed on the surface of the first conductive layer 16. The second conductive layer 17 covers the core material 4 and the first conductive layer 16. The second conductive layer 17 has a plurality of protrusions 17a on the outer surface. The plurality of core materials 4 are embedded in the second conductive layer 17. The core substance 4 is disposed inside the protrusion 17a. The outer surface of the second conductive layer 17 is raised by the plurality of core materials 4 to form protrusions 17a.

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

3 includes a base particle 2, a conductive layer 22, a plurality of core materials 4, and an insulating material 5. The conductive particles 21 shown in FIG. The conductive layer 22 is disposed on the surface of the base particle 2. The conductive layer 22 covers the base particle 2. The conductive layer 22 has a plurality of protrusions 22a on the outer surface.

In the conductive particles 21, a multilayer conductive layer 22 is formed. The conductive layer 22 includes a first conductive layer 26, a second conductive layer 27, and a third conductive layer 28. The first conductive layer 26 is disposed on the surface of the base particle 2. The first conductive layer 26 covers the base particle 2.

The core material 4 is disposed on the first conductive layer 26. The core material 4 is embedded in the conductive layer 22 and the second conductive layer 27. A first conductive layer 26 is disposed between the base particle 2 and the core substance 4. By disposing the first conductive layer 26 between the base material particle 2 and the core material 4, the surface of the base material particle 2 and the surface of the core material 4 are separated from each other. The average distance between the surface of the base particle 2 and the surface of the core substance 4 exceeds 5 nm. In the conductive particle 21, the distance between the surface of the base material particle 2 and the surface of the core material 4 is such that the conductive layer portion 22 b disposed between the surface of the base material particle 2 and the surface of the core material 4 and This is the thickness of the first conductive layer 26 portion.

The second conductive layer 27 is disposed on the surface of the first conductive layer 26. The second conductive layer 27 covers the core material 4 and the first conductive layer 26. The second conductive layer 27 has a plurality of protrusions 27a on the outer surface. The core substance 4 is disposed inside the protrusion 27a. The outer surface of the second conductive layer 27 is raised by the plurality of core materials 4, and protrusions 27 a are formed.

The third conductive layer 28 is disposed on the surface of the second conductive layer 27. The third conductive layer 28 covers the second conductive layer 27. The third conductive layer 28 has a plurality of protrusions 28a on the outer surface. The core substance 4 is disposed inside the protrusion 28a. The outer surface of the third conductive layer 28 is raised by the plurality of core materials 4 to form protrusions 28a.

It is preferable that the metal element contained most in the core material and the metal element contained most in the conductive layer are the same. In this case, as a result of good adhesion between the core substance and the conductive layer, the connection resistance in the connection structure is further improved. The metal element contained most in the core substance and the metal element contained most in the conductive layer are the core substance, the conductive layer, or the core substance and the conductive layer. There may be a concentration gradient. Moreover, the metal element contained most in the core substance and the metal element contained most in the conductive layer may be alloyed with other metals. The metal contained in the core material and the metal contained in the conductive layer may be alloyed at the interface.

It is preferable that the metal element contained most in the core material and the metal element contained most in the first conductive layer are the same. In this case, as a result of good adhesion between the core substance and the conductive layer, the connection resistance in the connection structure is further improved. The metal element contained most in the core material and the metal element contained most in the first conductive layer are the core material, the first conductive layer, or the core material and the above-described core material. There may be a concentration gradient in the first conductive layer. The metal element contained most in the first conductive layer may be alloyed with another metal. The metal contained in the core material and the metal contained in the first conductive layer may be alloyed at the interface.

It is preferable that the metal element contained most in the core material and the metal element contained most in the second conductive layer are the same. In this case, as a result of good adhesion between the core substance and the conductive layer, the connection resistance in the connection structure is further improved. The metal element contained most in the core material and the metal element contained most in the second conductive layer are the core material, the second conductive layer, or the core material and the above-described core material. There may be a concentration gradient in the second conductive layer. The metal element contained most in the second conductive layer may be alloyed with another metal. The metal contained in the core material and the metal contained in the second conductive layer may be alloyed at the interface.

The Mohs hardness of the core material is the same as the Mohs hardness of the conductive layer portion disposed between the base material particles and the core material, or the Mohs hardness of the core material is equal to the base material particles and the core material. It is preferable that it is larger than the Mohs hardness of the conductive layer part arrange | positioned between core materials. The Mohs hardness of the core material is preferably the same as the Mohs hardness of the first conductive layer, or the Mohs hardness of the core material is preferably larger than the Mohs hardness of the first conductive layer. In such a case, the core material is difficult to push the base material particles, and a part of the core material is difficult to sink into the base material particles. As a result, the connection resistance between the electrodes can be further reduced. From the viewpoint of further reducing the connection resistance between the electrodes, the Mohs hardness of the core substance is determined by the conductive layer portion disposed between the base material particles and the core substance or the Mohs of the first conductive layer. It is preferable that it is larger than the hardness.

When the Mohs hardness of the core material is equal to or higher than the Mohs hardness of the conductive layer portion or the first conductive layer disposed between the base material particles and the core material, the connection resistance is further increased. From the viewpoint of lowering, the absolute value of the difference between the Mohs hardness of the core material and the Mohs hardness of the conductive layer portion or the first conductive layer disposed between the base particle and the core material is: Preferably it is 0.1 or more, More preferably, it is 0.5 or more.

The Mohs hardness of the core substance is preferably smaller than the Mohs hardness of the conductive layer portion disposed between the base material particles and the core substance. The Mohs hardness of the core material is preferably smaller than the Mohs hardness of the first conductive layer. In these cases, the conductive layer portion and the first conductive layer have some cushioning properties. By this, not only can the connection resistance due to the conductive layer portion or the first conductive layer disposed between the base particle and the core substance be lowered, but also the connection structure in which the electrodes are connected by the conductive particles. Even when an impact is applied to the body, poor conduction is less likely to occur. That is, the impact resistance of the connection structure can be increased.

When the Mohs hardness of the core material is smaller than the Mohs hardness of the conductive layer portion or the first conductive layer disposed between the base particle and the core material, the impact resistance is further enhanced. From the viewpoint, the absolute value of the difference between the Mohs hardness of the core material and the Mohs hardness of the conductive layer portion or the first conductive layer disposed between the base particle and the core material is preferably 0.1 or more, more preferably 0.5 or more.

[Base material particles]
Examples of the substrate particles include resin particles, inorganic particles excluding metals, organic-inorganic hybrid particles, and metal particles. The substrate particles are preferably substrate particles excluding metal particles, and more preferably resin particles, inorganic particles excluding metal, or organic-inorganic hybrid particles.

The base material particles are preferably resin particles formed of a resin. When the substrate particles are resin particles, the effect of reducing the connection resistance obtained by the configuration of the conductive layer and the core substance of the present invention is considerably increased. When connecting between electrodes using the said electroconductive particle, after arrange | positioning the said electroconductive particle between electrodes, the said electroconductive particle is compressed by crimping | bonding. When the substrate particles are resin particles, the conductive particles are easily deformed during the pressure bonding, and the contact area between the conductive particles and the electrode is increased. For this reason, the conduction | electrical_connection reliability between electrodes becomes high.

Various organic substances are suitably used as the resin for forming the resin particles. Examples of the resin for forming the resin particles include polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polypropylene, polyisobutylene, and polybutadiene; acrylic resins such as polymethyl methacrylate and polymethyl acrylate. Polyalkylene terephthalate, polycarbonate, polyamide, phenol formaldehyde resin, 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, polysulfone , Polyphenylene oxide, polyacetal, polyimide, polyamideimide, poly Ether ketone, polyether sulfone, and polymers such as obtained by a variety of polymerizable monomer having an ethylenically unsaturated group is polymerized with one or more thereof. Resin for forming the resin particles can be designed and synthesized, and the hardness of the base particles can be easily controlled within a suitable range, which is suitable for conductive materials and having physical properties at the time of compression. Is preferably a polymer obtained by polymerizing one or more polymerizable monomers having a plurality of ethylenically unsaturated groups.

When the resin particles are obtained by polymerizing a monomer having an ethylenically unsaturated group, the monomer having an ethylenically unsaturated group includes a non-crosslinkable monomer and a crosslinkable monomer. And so on.

Examples of the non-crosslinkable monomer include styrene monomers such as styrene and α-methylstyrene; carboxyl group-containing monomers such as (meth) acrylic acid, maleic acid, and maleic anhydride; (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 ( Alkyl (meth) acrylates such as meth) acrylate and isobornyl (meth) acrylate; acids such as 2-hydroxyethyl (meth) acrylate, glycerol (meth) acrylate, polyoxyethylene (meth) acrylate and glycidyl (meth) acrylate Atom-containing (meth) acrylates; Nitrile-containing monomers such as (meth) acrylonitrile; Vinyl ethers such as methyl vinyl ether, ethyl vinyl ether and propyl vinyl ether; Vinyl acetates such as vinyl acetate, vinyl butyrate, vinyl laurate and vinyl stearate Esters; Unsaturated hydrocarbons such as ethylene, propylene, isoprene and butadiene; Halogen-containing monomers such as trifluoromethyl (meth) acrylate, pentafluoroethyl (meth) acrylate, vinyl chloride, vinyl fluoride and chlorostyrene Is mentioned.

Examples of the crosslinkable monomer include tetramethylolmethane tetra (meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolmethane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and dipenta Erythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, glycerol tri (meth) acrylate, glycerol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) Polyfunctional (meth) acrylates such as acrylate, (poly) tetramethylene di (meth) acrylate, 1,4-butanediol di (meth) acrylate; triallyl (iso) cyanurate, tri Lil trimellitate, divinyl benzene, diallyl phthalate, diallyl acrylamide, diallyl ether, .gamma. (meth) acryloxy propyl trimethoxy silane, trimethoxy silyl styrene, include silane-containing monomers such as vinyltrimethoxysilane.

The resin particles can be obtained by polymerizing the polymerizable monomer having an ethylenically unsaturated group by a known method. Examples of this method include a method of suspension polymerization in the presence of a radical polymerization initiator, and a method of polymerizing by swelling a monomer together with a radical polymerization initiator using non-crosslinked seed particles.

When the substrate particles are inorganic particles or organic-inorganic hybrid particles excluding metal particles, examples of the inorganic material for forming the substrate particles include silica and carbon black. Although it does not specifically limit as the particle | grains formed with the said silica, For example, after hydrolyzing the silicon compound which has two or more hydrolysable alkoxysil groups, and forming a crosslinked polymer particle, it calcinates as needed. The particle | grains obtained by performing are mentioned. Examples of the organic / inorganic hybrid particles include organic / inorganic hybrid particles formed of a crosslinked alkoxysilyl polymer and an acrylic resin.

When the substrate particles are metal particles, examples of the metal for forming the metal particles include silver, copper, nickel, silicon, gold, and titanium. However, the substrate particles are preferably not metal particles.

The particle diameter of the substrate particles is preferably 0.1 μm or more, more preferably 0.5 μm or more, still more preferably 1 μm or more, still more preferably 1.5 μm or more, particularly preferably 2 μm or more, preferably 1000 μm or less, More preferably, it is 500 μm or less, still more preferably 300 μm or less, still more preferably 50 μm or less, still more preferably 30 μm or less, particularly preferably 5 μm or less, and most preferably 3 μm or less. When the particle diameter of the substrate particles is equal to or greater than the above lower limit, the contact area between the conductive particles and the electrodes is increased, so that the conduction reliability between the electrodes is further increased, and the electrodes are connected via the conductive particles. The connection resistance between them becomes even lower. Further, when forming the conductive layer on the surface of the base particle by electroless plating, it becomes difficult to aggregate and the aggregated conductive particles are hardly formed. When the particle diameter is not more than the above upper limit, the conductive particles are easily compressed, the connection resistance between the electrodes is further reduced, and the distance between the electrodes is further reduced. The particle diameter of the base particle indicates a diameter when the base particle is a true sphere, and indicates a maximum diameter when the base particle is not a true sphere.

The particle diameter of the substrate particles is particularly preferably 0.1 μm or more and 5 μm or less. When the particle diameter of the substrate particles is in the range of 0.1 to 5 μm, even when the distance between the electrodes is small and the thickness of the conductive layer is increased, small conductive particles can be obtained. From the standpoint of obtaining even smaller conductive particles even when the distance between the electrodes is further reduced or the conductive layer is thickened, the particle diameter of the substrate particles is preferably 0.5 μm or more. More preferably, it is 2 μm or more, preferably 3 μm or less.

[Conductive layer]
The metal for forming the conductive layer is not particularly limited. Furthermore, when the conductive particles are metal particles that are conductive layers as a whole, the metal for forming the metal particles is not particularly limited. Examples of the metal include gold, silver, copper, palladium, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, thallium, germanium, cadmium, silicon, and tungsten. , Molybdenum, and alloys thereof. Examples of the metal include tin-doped indium oxide (ITO) and solder. Especially, since the connection resistance between electrodes can be made still lower, an alloy containing tin, nickel, palladium, copper or gold is preferable, and nickel or palladium is more preferable. The metal element constituting the conductive layer preferably contains nickel. The conductive layer preferably contains at least one selected from the group consisting of nickel, tungsten, molybdenum, palladium, phosphorus and boron, and more preferably contains nickel and phosphorus or boron. The material forming the conductive layer may be an alloy containing phosphorus, boron, or the like. In the conductive layer, nickel and tungsten or molybdenum may be alloyed.

When the conductive layer contains phosphorus or boron, the total content of phosphorus and boron is preferably 4% by weight or less in 100% by weight of the conductive layer. When the total content of phosphorus and boron is not more than the above upper limit, the content of metals such as nickel is relatively increased, so that the connection resistance between the electrodes is further reduced. In 100% by weight of the conductive layer, the total content of phosphorus and boron is preferably 0.1% by weight or more, more preferably 0.5% by weight or more.

The metal element contained most in the core material, the conductive layer, and the second conductive layer is preferably an alloy containing tin, nickel, palladium, copper, or gold, and more preferably nickel or palladium. .

Like the conductive particles 1, the conductive layer may be formed of a single layer. Furthermore, like the conductive particles 11 and 21, the conductive layer may be formed of a plurality of layers. That is, the conductive layer may be a single layer or may have a stacked structure of two or more layers. When the conductive layer is formed of a plurality of layers, the outermost layer is preferably a gold layer, a nickel layer, a palladium layer, a copper layer, or an alloy layer containing tin and silver, and the gold layer or the palladium layer Is more preferable, and a gold layer is particularly preferable. When the outermost layer is these preferred conductive layers, the connection resistance between the electrodes is further reduced. Moreover, when the outermost layer is a gold layer, the corrosion resistance is further enhanced.

The method for forming the conductive layer on the surface of the substrate particles is not particularly limited. As a method for forming the conductive layer, for example, a method by electroless plating, a method by electroplating, a method by physical vapor deposition, and a method of coating the surface of base particles with metal powder or a paste containing metal powder and a binder Etc. Especially, since formation of a conductive layer is simple, the method by electroless plating is preferable. Examples of the method by physical vapor deposition include methods such as vacuum vapor deposition, ion plating, and ion sputtering.

The average particle diameter of the conductive particles is preferably 0.11 μm or more, more preferably 0.5 μm or more, further preferably 0.51 μm or more, particularly preferably 1 μm or more, preferably 100 μm or less, more preferably 20 μm or less, More preferably, it is 5.6 micrometers or less, Most preferably, it is 3.6 micrometers or less. It is. When the average particle diameter of the conductive particles is not less than the above lower limit and not more than the above upper limit, the contact area between the conductive particles and the electrode becomes sufficiently large when the electrodes are connected using the conductive particles, and the conductive Aggregated conductive particles are less likely to be formed when the layer is formed. Further, the distance between the electrodes connected via the conductive particles does not become too large, and the conductive layer is difficult to peel from the surface of the base material particles.

The “average particle size” of the conductive particles indicates a number average particle size. The average particle diameter of the conductive particles can be obtained by observing 50 arbitrary conductive particles with an electron microscope or an optical microscope and calculating an average value.

The thickness of the conductive layer is preferably 0.005 μm or more, more preferably 0.01 μm or more, preferably 1 μm or less, more preferably 0.3 μm or less. When the thickness of the conductive layer is not less than the above lower limit and not more than the above upper limit, sufficient conductivity is obtained, and the conductive particles do not become too hard, and the conductive particles are sufficiently deformed when connecting the electrodes. .

When the conductive layer is formed of a plurality of layers, the thickness of the outermost conductive layer is preferably 0.001 μm or more, more preferably 0.01 μm or more, preferably 0.5 μm or less, more preferably 0. .1 μm or less. When the thickness of the outermost conductive layer is not less than the above lower limit and not more than the above upper limit, the coating with the outermost conductive layer can be made uniform, corrosion resistance can be sufficiently enhanced, and the connection resistance between the electrodes can be increased. It can be made sufficiently low.

The thickness of the conductive layer can be measured by observing the cross section of the conductive particles or the conductive particles with insulating particles using, for example, a transmission electron microscope (TEM).

The number of protrusions on the outer surface of the conductive layer per one of the conductive particles is preferably 3 or more, more preferably 5 or more. The upper limit of the number of protrusions is not particularly limited. The upper limit of the number of protrusions can be appropriately selected in consideration of the average particle diameter of conductive particles and the like.

[Core material]
Since the core substance is embedded in the conductive layer, the conductive layer has a plurality of protrusions on the outer surface.

As a method for forming the protrusions, a first conductive layer is formed on the surface of the base particle, a core substance is disposed on the first conductive layer, and then a second conductive layer is formed. Examples thereof include a method and a method of adding a core substance in the middle of forming a conductive layer on the surface of the base particle.

As the material constituting the core material, there may be mentioned a conductive material and a non-conductive material. Examples of the conductive material include conductive non-metals such as metals, metal oxides, and graphite, and conductive polymers. Examples of the conductive polymer include polyacetylene. Examples of the non-conductive substance include silica, alumina, barium titanate, zirconia, and the like. Among them, metal is preferable because conductivity can be increased and connection resistance can be effectively reduced. The core substance is preferably metal particles.

Examples of the metal include gold, silver, copper, platinum, zinc, iron, lead, tin, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium and cadmium, and tin-lead. Examples thereof include alloys composed of two or more metals such as alloys, tin-copper alloys, tin-silver alloys, tin-lead-silver alloys, and tungsten carbide. Of these, nickel, copper, silver or gold is preferable. The metal constituting the core material may be the same as or different from the metal constituting the conductive layer. The metal constituting the core material preferably includes a metal constituting the conductive layer. It is preferable that the metal which comprises the said core substance contains nickel. It is preferable that the metal which comprises the said core substance contains nickel.

The shape of the core substance is not particularly limited. The shape of the core substance is preferably a lump. Examples of the core substance include a particulate lump, an agglomerate in which a plurality of fine particles are aggregated, and an irregular lump.

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

The “average diameter (average particle diameter)” of the core substance indicates a number average diameter (number average particle diameter). The average diameter of the core material is obtained by observing 50 arbitrary core materials with an electron microscope or an optical microscope and calculating an average value.

Inorganic particles may be disposed on the surface of the core substance. It is preferable that there are a plurality of inorganic particles arranged on the surface of the core substance. Inorganic particles may be attached to the surface of the core substance. You may use the composite particle provided with such an inorganic particle and a core substance. The size (average diameter) of the inorganic particles is preferably smaller than the size (average diameter) of the core substance, and the inorganic particles are preferably inorganic fine particles.

Examples of the material of the inorganic particles arranged on the surface of the core substance include barium titanate (Mohs hardness 4.5), silica (silicon dioxide, Mohs hardness 6-7), zirconia (Mohs hardness 8-9), Examples include alumina (Mohs hardness 9), tungsten carbide (Mohs hardness 9), diamond (Mohs hardness 10), and the like. The inorganic particles are preferably silica, zirconia, alumina, tungsten carbide or diamond, and are also preferably silica, zirconia, alumina or diamond. The Mohs hardness of the inorganic particles is preferably 5 or more, more preferably 6 or more. The Mohs hardness of the inorganic particles is preferably larger than the Mohs hardness of the conductive layer. The Mohs hardness of the inorganic particles is preferably larger than the Mohs hardness of the second conductive layer. The absolute value of the difference between the Mohs hardness of the inorganic particles and the Mohs hardness of the conductive layer, and the absolute value of the difference between the Mohs hardness of the inorganic particles and the Mohs hardness of the second conductive layer are preferably 0.1. Above, more preferably 0.2 or more, still more preferably 0.5 or more, particularly preferably 1 or more. Further, when the conductive layer is formed of a plurality of layers, the effect of reducing the connection resistance is more effectively exhibited when the inorganic particles are harder than all the metals constituting the plurality of layers.

The average particle size of the inorganic particles is preferably 0.0001 μm or more, more preferably 0.005 μm or more, preferably 0.5 μm or less, more preferably 0.1 μm or less. When the average particle size of the inorganic 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 effectively reduced.

The “average particle size” of the inorganic particles indicates the number average particle size. The average particle diameter of the inorganic particles is obtained by observing 50 arbitrary inorganic particles with an electron microscope or an optical microscope and calculating an average value.

When using composite particles in which inorganic particles are arranged on the surface of the core substance, the average diameter of the composite particles (average particle diameter) is preferably 0.0012 μm or more, more preferably 0.0502 μm or more, preferably Is 1.9 μm or less, more preferably 1.2 μm or less. When the average diameter of the composite 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 effectively reduced.

The “average diameter (average particle diameter)” of the composite particles indicates a number average diameter (number average particle diameter). The average diameter of the composite particles is determined by observing 50 arbitrary composite particles with an electron microscope or an optical microscope and calculating an average value.

[Insulating material]
The conductive particles according to the present invention preferably include an insulating material disposed on the surface of the conductive layer. In this case, when the conductive particles are used for connection between the electrodes, a short circuit between adjacent electrodes can be prevented. Specifically, when a plurality of conductive particles are in contact with each other, an insulating material is present between the plurality of electrodes, so that it is possible to prevent a short circuit between electrodes adjacent in the lateral direction instead of between the upper and lower electrodes. Note that when the conductive particles are pressurized with the two electrodes at the time of connection between the electrodes, the insulating substance between the conductive layer of the conductive particles and the electrodes can be easily excluded. Since the conductive particles have a plurality of protrusions on the outer surface of the conductive layer, the insulating material between the conductive layer of the conductive particles and the electrode can be easily excluded.

It is preferable that the insulating material is an insulating particle because the insulating material can be more easily removed when the electrodes are crimped.

Specific examples of the insulating resin that is the material of the insulating material include polyolefins, (meth) acrylate polymers, (meth) acrylate copolymers, block polymers, thermoplastic resins, crosslinked thermoplastic resins, and thermosetting. Resin, water-soluble resin, and the like.

Examples of the polyolefins include polyethylene, ethylene-vinyl acetate copolymer, and ethylene-acrylic acid ester copolymer. Examples of the (meth) acrylate polymer include polymethyl (meth) acrylate, polyethyl (meth) acrylate, and polybutyl (meth) acrylate. Examples of the block polymer include polystyrene, styrene-acrylate 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. As said thermosetting resin, an epoxy resin, a phenol resin, a melamine resin, etc. are mentioned. Examples of the water-soluble resin include polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyvinyl pyrrolidone, polyethylene oxide, and methyl cellulose. Of these, water-soluble resins are preferable, and polyvinyl alcohol is more preferable.

Examples of a method for disposing an insulating material on the surface of the conductive layer 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, spraying, dipping, and vacuum deposition. In particular, since the insulating substance is difficult to be detached, a method of disposing the insulating substance on the surface of the conductive layer through a chemical bond is preferable.

The average diameter (average particle diameter) of the insulating material can be appropriately selected depending on the particle diameter of the conductive particles and the use of the conductive particles. The average diameter (average particle diameter) of the insulating material is preferably 0.005 μm or more, more preferably 0.01 μm or more, preferably 1 μm or less, more preferably 0.5 μm or less. When the average diameter of the insulating material is not less than the above lower limit, the conductive layers of the plurality of conductive particles are difficult to contact when the conductive particles are dispersed in the binder resin. When the average diameter of the insulating particles is not more than the above upper limit, it is not necessary to make the pressure too high in order to eliminate the insulating material between the electrodes and the conductive particles when the electrodes are connected. There is no need for heating.

The “average diameter (average particle diameter)” of the insulating material indicates a number average diameter (number average particle diameter). The average diameter of the insulating material is obtained using a particle size distribution measuring device or the like.

(Conductive material)
The conductive material according to the present invention includes the conductive particles described above and a binder resin. The conductive particles are preferably dispersed in a binder resin and used as a conductive material. The conductive material is preferably an anisotropic conductive material.

The binder resin is not particularly limited. As the binder resin, a known insulating resin is used.

Examples of the binder resin include vinyl resins, thermoplastic resins, curable resins, thermoplastic block copolymers, and elastomers. As for the said binder resin, only 1 type may be used and 2 or more types may be used together.

Examples of the vinyl resin include vinyl acetate resin, acrylic resin, and styrene resin. Examples of the thermoplastic resin include polyolefin resin, ethylene-vinyl acetate copolymer, and polyamide resin. Examples of the curable resin include an epoxy resin, a urethane resin, a polyimide resin, and an unsaturated polyester resin. 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 product of a styrene-butadiene-styrene block copolymer, and a styrene-isoprene. -Hydrogenated products of styrene block copolymers. 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, an extender, a softener, a plasticizer, a polymerization catalyst, a curing catalyst, a colorant, an antioxidant, a heat stabilizer, and a light stabilizer. Various additives such as an agent, an ultraviolet absorber, a lubricant, an antistatic agent and a flame retardant may be contained.

The method for dispersing the conductive particles in the binder resin is not particularly limited, and a conventionally known dispersion method can be used. Examples of a method for dispersing the conductive particles in the binder resin include 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. The conductive particles are dispersed in water. Alternatively, after uniformly dispersing in an organic solvent using a homogenizer or the like, it is added to the binder resin and kneaded with a planetary mixer or the like, and the binder resin is diluted with water or an organic solvent. Then, the method of adding the said electroconductive particle, kneading with a planetary mixer etc. and disperse | distributing is mentioned.

The conductive material according to the present invention can be used as a conductive paste and a conductive film. When the conductive material according to the present invention is a conductive film, a film that does not include conductive particles may be laminated on a conductive film that includes conductive particles. The conductive paste is preferably an anisotropic conductive paste. The conductive film is preferably an anisotropic conductive film.

In 100% by weight of the conductive material, the content of the binder resin is preferably 10% by weight or more, more preferably 30% by weight or more, still more preferably 50% by weight or more, particularly preferably 70% by weight or more, preferably 99.% or more. It is 99 weight% or less, More preferably, it is 99.9 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 increased.

In 100% by weight of the conductive material, the content of the conductive particles is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, preferably 40% by weight or less, more preferably 20% by weight or less, More preferably, it is 10 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 conduction reliability between the electrodes is further enhanced.

(Connection structure)
A connection structure can be obtained by connecting the connection target members using the conductive particles of the present invention or using a conductive material containing the conductive particles and a binder resin.

The connection structure includes a first connection target member, a second connection target member, and a connection portion connecting the first and second connection target members, and the connection portion is a conductive member of the present invention. The connection structure is preferably formed of conductive particles or formed of a conductive material (such as an anisotropic conductive material) containing the conductive particles and a binder resin. In the case where conductive particles are used, the connection portion itself is conductive particles. That is, the first and second connection target members are connected by the conductive particles.

FIG. 4 is a front cross-sectional view schematically showing a connection structure using conductive particles according to the first embodiment of the present invention.

4 includes a first connection target member 52, a second connection target member 53, and a connection portion 54 that connects the first and second

connection target members

52 and 53. Prepare. The connection portion 54 is formed by curing a conductive material including the conductive particles 1. In FIG. 4, the conductive particles 1 are schematically shown for convenience of illustration.

The first connection target member 52 has a plurality of electrodes 52b on the upper surface 52a (front surface). The second connection target member 53 has a plurality of electrodes 53b on the lower surface 53a (front surface). The electrode 52 b and the electrode 53 b are electrically connected by one or a plurality of conductive particles 1. Therefore, the first and second

connection target members

52 and 53 are electrically connected by the conductive particles 1.

The manufacturing method of the connection structure is not particularly limited. As an example of the manufacturing method of the connection structure, the conductive material is disposed between the first connection target member and the second connection target member to obtain a laminate, and then the laminate is heated and pressurized. Methods and the like.

The pressurizing pressure is about 9.8 × 10 ⁴ to 4.9 × 10 ⁶ Pa. The heating temperature is about 120 to 220 ° C.

Specific examples of the connection target member include electronic components such as semiconductor chips, capacitors, and diodes, and electronic components such as circuit boards such as printed boards, flexible printed boards, and glass boards. The connection target member is preferably an electronic component. The conductive particles are preferably used for electrical connection of electrodes in an electronic component.

Examples of the electrode provided on the connection target member include metal electrodes such as a gold electrode, a nickel electrode, a tin electrode, an aluminum electrode, a copper electrode, a molybdenum electrode, and a tungsten electrode. When the connection object member is a flexible printed board, the electrode is preferably a gold electrode, a nickel electrode, a tin electrode, or a copper electrode. When the connection target member is a glass substrate, the electrode is preferably an aluminum electrode, a copper electrode, a molybdenum electrode, or a tungsten electrode. In addition, when the said electrode is an aluminum electrode, the electrode formed only with aluminum may be sufficient and the electrode by which the aluminum layer was laminated | stacked on the surface of the metal oxide layer may be sufficient. Examples of the material for 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 only to the following examples.

Example 1
(1) Palladium adhesion process Divinylbenzene resin particles (“Micropearl SP-205” manufactured by Sekisui Chemical Co., Ltd.) having a particle diameter of 5.0 μm were prepared. The resin particles were etched and washed with water. Next, resin particles were added to 100 mL of a palladium-catalyzed solution containing 8% by weight of a palladium catalyst and stirred. Then, it filtered and wash | cleaned. Resin particles were added to 0.5 wt% dimethylamine borane solution at pH 6 to obtain resin particles to which palladium was attached.

(2) Electroless nickel plating step In order to form a nickel-phosphorus conductive layer, nickel sulfate 0.25 mol / L, sodium hypophosphite 0.25 mol / L, sodium citrate 0.15 mol / L and sodium molybdate A nickel plating solution (pH 8.0) containing 0.01 mol / L was prepared.

A suspension was obtained by adding the resin particles to which palladium obtained in 1000 mL of pure water was adhered and dispersing with an ultrasonic disperser. While stirring the obtained suspension at 60 ° C., the nickel plating solution was gradually added dropwise to the suspension to perform electroless nickel plating. Thereafter, the suspension is filtered to remove the particles, washed with water, and dried to obtain a first conductive layer (nickel-molybdenum-phosphorus layer (Ni-Mo-P layer)) The resin particles were coated at a thickness of 5.2 nm) to obtain particles on which the first conductive layer was formed.

(3) Core substance adhering step and electroless nickel plating step An alumina (Al ₂ O ₃ ) particle slurry (average particle size 100 nm) was prepared. It coat | covered using the particle | grains in which the 1st conductive layer was formed, and metal particle slurry.

Nickel containing 0.25 mol / L nickel sulfate, 0.25 mol / L sodium hypophosphite, 0.15 mol / L sodium citrate and 0.01 mol / L sodium molybdate to form a nickel-phosphorus conductive layer A plating solution (pH 8.0) was prepared.

While stirring the obtained suspension at 60 ° C., the above nickel plating solution is gradually dropped into the suspension, electroless nickel plating is performed, and a second conductive layer (nickel-molybdenum-phosphorus) having a thickness of 90 nm is obtained. A layer (Ni—Mo—P layer) was formed, and then the suspension was filtered to take out the particles, washed with water, and dried to obtain conductive particles. , Having a protrusion on the outer surface of the second conductive layer, and a core substance disposed on the inner side of the protrusion of the second conductive layer, and the first conductive layer between the resin particles and the core substance. Layers were placed.

(Example 2)
Conductive particles were obtained in the same manner as in Example 1 except that the alumina (Al ₂ O ₃ ) particle slurry (average particle size 100 nm) was changed to a silica particle slurry (average particle size 100 nm).

(Example 3)
Conductive particles were obtained in the same manner as in Example 1 except that the alumina (Al ₂ O ₃ ) particle slurry (average particle size 100 nm) was changed to a tungsten carbide (WC) particle slurry (average particle size 100 nm).

(Examples 4 to 8)
Conductive particles were obtained in the same manner as in Example 1 except that the thickness of the first conductive layer, which was a nickel-phosphorous layer, was changed to the value shown below.

The thickness of the first conductive layer:
Example 4: 10 μm
Example 5: 20 μm
Example 6: 100 μm
Example 7: 750 μm
Example 8: 860 μm

Example 9
(1) Preparation of insulating particles Into a 1000 mL separable flask equipped with a four-neck separable cover, stirring blade, three-way cock, cooling tube and temperature probe, 100 mmol of methyl methacrylate and N, N, N-trimethyl Ion-exchanged water containing a monomer composition containing 1 mmol of —N-2-methacryloyloxyethylammonium chloride and 1 mmol of 2,2′-azobis (2-amidinopropane) dihydrochloride so that the solid content is 5% by weight. Then, the mixture was stirred at 200 rpm and polymerized at 70 ° C. for 24 hours under a nitrogen atmosphere. After completion of the reaction, it was freeze-dried to obtain insulating particles having an ammonium group on the surface, an average particle size of 220 nm, and a CV value of 10%.

The insulating particles were dispersed in ion exchange water under ultrasonic irradiation to obtain a 10 wt% aqueous dispersion of insulating particles.

10 g of the conductive particles obtained in Example 1 were dispersed in 500 mL of ion-exchanged water, 4 g of an aqueous dispersion of insulating particles was added, and the mixture was stirred at room temperature for 6 hours. After filtration through a 3 μm mesh filter, the particles were further washed with methanol and dried to obtain conductive particles having insulating particles attached thereto.

When observed with a scanning electron microscope (SEM), only one coating layer of insulating particles was formed on the surface of the conductive particles. The coverage of the insulating particles with respect to the area of 2.5 μm from the center of the conductive particles by image analysis (that is, the projected area of the particle diameter of the insulating particles) was calculated to be 30%.

(Example 10)
Divinylbenzene resin particles having a particle diameter of 5.0 μm (“Micropearl SP-205” manufactured by Sekisui Chemical Co., Ltd.) and divinylbenzene resin particles having a particle diameter of 5.0 μm (“Micropearl SP manufactured by Sekisui Chemical Co., Ltd.) are used. Conductive particles were obtained in the same manner as in Example 1 except that the surface of -205 ") was changed to silica-coated organic-inorganic hybrid particles (particle diameter 5.1 μm).

(Comparative Example 1)
Conductive particles were obtained in the same manner as in Example 1 except that the thickness of the first conductive layer, which was a nickel-phosphorous layer, was changed to 4.5 nm.

(Comparative Example 2)
Divinylbenzene resin particles (“Micropearl SP-205” manufactured by Sekisui Chemical Co., Ltd.) having a particle diameter of 5.0 μm were prepared. Moreover, an alumina (Al ₂ O ₃ ) particle slurry (average particle diameter: 100 nm) was prepared. Using resin particles and metal particle slurry, the surface of the resin particles was coated with a core substance to obtain a suspension.

While stirring the obtained suspension at 60 ° C., the nickel plating solution was gradually added dropwise to the suspension, and electroless nickel plating was performed to form a conductive layer having a thickness of 100 nm. Thereafter, the suspension was filtered to take out the particles, washed with water, and dried to obtain conductive particles. In the obtained conductive particles, the core substance and the base material particles were in contact.

(Example 11)
(1) Palladium adhesion process The resin particle to which the palladium obtained in Example 1 was adhered was prepared.

(2) Electroless nickel plating step Nickel plating solution containing 0.23 mol / L nickel sulfate, 0.92 mol / L dimethylamine borane, 0.5 mol / L sodium citrate and 0.01 mol / L sodium tungstate (pH 8. 5) was prepared.

A suspension was obtained by adding the resin particles to which palladium obtained in 1000 mL of pure water was adhered and dispersing with an ultrasonic disperser. While stirring the obtained suspension at 60 ° C., the nickel plating solution was gradually added dropwise to the suspension to perform electroless nickel plating. Thereafter, by filtering the suspension, the particles are taken out, washed with water, and dried to cover the resin particles with the first conductive layer (thickness 5.1 nm) which is a nickel-tungsten-boron layer. The particle | grains in which the 1st conductive layer was formed were obtained.

A nickel plating solution (pH 8.5) containing 0.23 mol / L of nickel sulfate, 0.92 mol / L of dimethylamine borane, 0.5 mol / L of sodium citrate and 0.01 mol / L of sodium tungstate was prepared.

While stirring the obtained suspension at 60 ° C., the above nickel plating solution was gradually added dropwise to the suspension, and electroless nickel plating was performed to form a second conductive layer having a thickness of 90 nm. Thereafter, the suspension was filtered to take out the particles, washed with water, and dried to obtain conductive particles. The obtained conductive particles had protrusions on the outer surface of the second conductive layer, and the core substance was disposed inside the protrusions of the second conductive layer. Moreover, the 1st conductive layer was arrange | positioned between the resin particle and the core substance.

Example 12
Conductive particles were obtained in the same manner as in Example 11 except that the thickness of the first conductive layer, which was a nickel-tungsten-boron layer, was changed to 10 nm.

(Example 13)
Conductive particles were obtained in the same manner as in Example 11 except that the thickness of the first conductive layer, which was a nickel-tungsten-boron layer, was changed to 20 nm.

(Example 14)
A 10% by weight aqueous dispersion of the insulating particles obtained in Example 9 was prepared. 10 g of the conductive particles obtained in Example 11 were dispersed in 500 mL of ion exchange water, 4 g of an aqueous dispersion of insulating particles was added, and the mixture was stirred at room temperature for 6 hours. After filtration through a 3 μm mesh filter, the particles were further washed with methanol and dried to obtain conductive particles having insulating particles attached thereto.

(Comparative Example 3)
Conductive particles were obtained in the same manner as in Example 11 except that the thickness of the first conductive layer, which was a nickel-tungsten-boron layer, was changed to 3 nm.

(Comparative Example 4)
Divinylbenzene resin particles (“Micropearl SP-205” manufactured by Sekisui Chemical Co., Ltd.) having a particle diameter of 5.0 μm were prepared. Moreover, an alumina (Al ₂ O ₃ ) particle slurry (average particle diameter: 100 nm) was prepared. Using resin particles and metal particle slurry, the surface of the resin particles was coated with a core substance to obtain a suspension.

(Example 15)
(1) Palladium adhesion process The resin particle to which the palladium obtained in Example 1 was adhered was prepared.

A suspension was obtained by adding the resin particles to which palladium obtained in 1000 mL of pure water was adhered and dispersing with an ultrasonic disperser. While stirring the obtained suspension at 60 ° C., the nickel plating solution was gradually added dropwise to the suspension to perform electroless nickel plating. Thereafter, the suspension is filtered to remove the particles, washed with water, and dried to coat the resin particles with the first conductive layer having a thickness of 10 nm, which is a nickel-tungsten-boron layer. Particles with a conductive layer formed were obtained.

(3) Core substance adhesion step and electroless nickel plating step A barium titanate (BaTiO ₃ ) particle slurry (average particle size of 100 nm) was prepared. Using the particles on which the first conductive layer was formed and the metal particle slurry, the surface of the first conductive layer was coated with metal particles to obtain a suspension.

A nickel plating solution (pH 7.0) containing 0.23 mol / L of nickel sulfate, 0.92 mol / L of dimethylamine borane and 0.5 mol / L of sodium citrate was prepared.

(Example 16)
Conductive particles were obtained in the same manner as in Example 15 except that the thickness of the first conductive layer, which was a nickel-tungsten-boron layer, was changed to 5.1 nm.

(Example 17)
Conductive particles were obtained in the same manner as in Example 15 except that the thickness of the first conductive layer, which was a nickel-tungsten-boron layer, was changed to 20 nm.

(Example 18)
Conductive particles were obtained in the same manner as in Example 15 except that the barium titanate (BaTiO ₃ ) particle slurry (average particle size 100 nm) was changed to alumina (Al ₂ O ₃ ) particle slurry (average particle size 100 nm). It was.

(Example 19)
Conductive particles were obtained in the same manner as in Example 16 except that the barium titanate (BaTiO ₃ ) particle slurry (average particle size 100 nm) was changed to alumina (Al ₂ O ₃ ) particle slurry (average particle size 100 nm). It was.

(Example 20)
Conductive particles were obtained in the same manner as in Example 17 except that the barium titanate (BaTiO ₃ ) particle slurry (average particle size 100 nm) was changed to alumina (Al ₂ O ₃ ) particle slurry (average particle size 100 nm). It was.

(Example 21)
Conductive particles were obtained in the same manner as in Example 15 except that sodium tungstate 0.01 mol / L was added to the nickel plating solution for forming the second conductive layer.

(Example 22)
A 10% by weight aqueous dispersion of the insulating particles obtained in Example 9 was prepared. 10 g of the conductive particles obtained in Example 15 were dispersed in 500 mL of ion-exchanged water, 4 g of an aqueous dispersion of insulating particles was added, and the mixture was stirred at room temperature for 6 hours. After filtration through a 3 μm mesh filter, the particles were further washed with methanol and dried to obtain conductive particles having insulating particles attached thereto.

(Comparative Example 5)
Divinylbenzene resin particles (“Micropearl SP-205” manufactured by Sekisui Chemical Co., Ltd.) having a particle diameter of 5.0 μm were prepared. Moreover, barium titanate (BaTiO ₃ ) particle slurry (average particle diameter: 100 nm) was prepared. Using resin particles and metal particle slurry, the surface of the resin particles was coated with a core substance to obtain a suspension.

(Comparative Example 6)
Conductive particles were obtained in the same manner as in Example 18 except that the thickness of the first conductive layer, which was a nickel-tungsten-boron layer, was changed to 1 nm.

(Example 23)
A 10% by weight aqueous dispersion of the insulating particles obtained in Example 9 was prepared. 10 g of the conductive particles obtained in Example 18 were dispersed in 500 mL of ion-exchanged water, 4 g of an aqueous dispersion of insulating particles was added, and the mixture was stirred at room temperature for 6 hours. After filtration through a 3 μm mesh filter, the particles were further washed with methanol and dried to obtain conductive particles having insulating particles attached thereto.

(Evaluation)
(1) Average distance between the surface of the base particle and the surface of the core material The distance between the surface of the base particle and a plurality of core materials by cutting the obtained conductive particles and observing the cross section Was measured. The distance between the surface of the base material particle and the surface of the core material is obtained by photographing a plurality of cross-sections of the conductive particles to obtain an image, creating a stereoscopic image from the obtained image, and obtaining the stereoscopic image It was measured by using. The above cross-section was photographed by FEI Japan, focused ion beam-scanning electron microscope (FIBSEM) apparatus name Helios NanoLab. 650. A thin film slice of conductive particles was prepared using a focused ion beam, and the cross section was observed with a scanning electron microscope. The operation was repeated 200 times, and image analysis was performed to obtain a three-dimensional image of the particles. From the stereoscopic image, the distance between the surface of the base particle and the surface of the core material was determined.

(2) The ratio (%) of the number of core materials in which the distance between the surface of the base material particles and the surface of the core material exceeds 5 nm in 100% by weight of the total number of core materials.
In the same manner as the evaluation item (1) above, the ratio (%) of the number of core materials in which the distance between the surface of the base material particles and the surface of the core material exceeds 5 nm in the total number of core materials of 100% by weight. Was measured and judged according to the following criteria.

[Criteria for the ratio (%) of the number of core materials in which the distance between the surface of the substrate particles and the surface of the core material exceeds 5 nm]
A: The ratio of the number exceeds 80% B: The ratio of the number is 80% or less

(3) Connection resistance Fabrication of connection structure:
10 parts by weight of bisphenol A type epoxy resin (“Epicoat 1009” manufactured by Mitsubishi Chemical Corporation), 40 parts by weight of acrylic rubber (weight average molecular weight of about 800,000), 200 parts by weight of methyl ethyl ketone, and a microcapsule type curing agent (Asahi Kasei Chemicals) "HX3941HP" manufactured by HX3941) and 2 parts by weight of a silane coupling agent ("SH6040" manufactured by Toray Dow Corning Silicone Co., Ltd.) are mixed, and the conductive particles are added so that the content is 3% by weight. A resin composition was obtained by dispersing.

The obtained resin composition was applied to a 50 μm-thick PET (polyethylene terephthalate) film whose one surface was release-treated, and dried with hot air at 70 ° C. for 5 minutes to produce an anisotropic conductive film. The thickness of the obtained anisotropic conductive film was 12 μm.

The obtained anisotropic conductive film was cut into a size of 5 mm × 5 mm. The cut anisotropic conductive film is formed of a glass substrate (width 3 cm, length 3 cm) having an aluminum electrode (height 0.2 μm, L / S = 20 μm / 20 μm) having a lead wire for resistance measurement on one side. Affixed almost at the center on the aluminum electrode side. Next, a two-layer flexible printed board (width 2 cm, length 1 cm) having the same aluminum electrode was aligned and aligned so that the electrodes overlapped. The laminated body of the glass substrate and the two-layer flexible printed circuit board was thermocompression bonded under pressure bonding conditions of 10 N, 180 ° C., and 20 seconds to obtain a connection structure. A two-layer flexible printed board in which an aluminum electrode is directly formed on a polyimide film was used.

Connection resistance measurement:
The connection resistance between the opposing electrodes of the obtained connection structure was measured by the 4-terminal method. Further, the connection resistance was determined according to the following criteria.

[Criteria for connection resistance]
○○: Connection resistance is 2.0Ω or less ○: Connection resistance exceeds 2.0Ω, 3.0Ω or less △: Connection resistance exceeds 3.0Ω, 5.0Ω or less ×: Connection resistance exceeds 5.0Ω

(4) Impact resistance The connection structure obtained by the evaluation of (3) connection resistance was dropped from a position of 70 cm in height, and the impact resistance was evaluated by confirming conduction. From the rate of increase in resistance value from the initial resistance value, impact resistance was determined according to the following criteria.

[Evaluation criteria for impact resistance]
○○: Resistance value increase rate from initial resistance value is 20% or less ○: Resistance value increase rate from initial resistance value exceeds 20%, 35% or less Δ: Resistance value increase rate from initial resistance value Exceeds 35% and 50% or less ×: The rate of increase in resistance value from the initial resistance value exceeds 50%

(5) Indentation state Using a differential interference microscope, the electrode provided on the glass substrate is observed from the glass substrate side of the connection structure obtained in the above (3) connection resistance evaluation, and the conductive particles are in contact with each other. The presence or absence of formation of indentations on the electrodes was evaluated according to the following criteria. In addition, the presence or absence of formation of the impression of the electrode was observed with a differential interference microscope so that the electrode area was 0.02 mm ^2, and the number of impressions per electrode area of 0.02 mm ² was calculated. Arbitrary ten places were observed with the differential interference microscope, and the average value of the number of indentations per electrode area of 0.02 mm ² was calculated.

[Criteria for indentation state]
◯: The average value of the number of impressions per electrode area 0.02 mm ² is 20 or more. Δ: The average value of the number of impressions per electrode area 0.02 mm ² is 5 or more and less than 20. ×: Electrode area 0. The average number of impressions per 02 mm ² is less than 5

The results are shown in Tables 1 to 3 below. Tables 1 to 3 below show the Mohs hardness of the first and second conductive layers and the core material. In Tables 1 to 3 below, “-” indicates no evaluation.

DESCRIPTION OF SYMBOLS 1 ... Conductive particle 2 ... Base material particle 3 ... Conductive layer 3a ... Protrusion 3b ... Conductive layer part 4 ... Core substance 5 ... Insulating substance 11 ... Conductive particle 12 ... Conductive layer 12a ... Protrusion 12b ... Conductive layer part 16 ... First 1 conductive layer 17 second conductive layer 17a projection 21 conductive particles 22 conductive layer 22a projection 22b conductive layer portion 26 first conductive layer 27 second conductive layer 27a projection 28 3rd conductive layer 28a ... projection 51 ... connection structure 52 ... 1st connection object member 52a ... upper surface 52b ... electrode 53 ... 2nd connection object member 53a ... lower surface 53b ... electrode 54 ... connection part

Claims

Substrate particles,
A conductive layer covering the substrate particles;
A plurality of core materials embedded in the conductive layer,
The conductive layer has a plurality of protrusions on the outer surface, and the core substance is disposed inside the protrusions of the conductive layer;
The conductive layer is disposed between the base material particle and the core material, and the surface of the base material particle and the surface of the core material are spaced apart from each other, and the surface of the base material particle and the core Conductive particles having an average distance from the surface of the substance of more than 5 nm.
The conductive particle according to claim 1, wherein an average distance between the surface of the substrate particle and the surface of the core substance is more than 5 nm and not more than 800 nm.
In a total number of 100% of the core material, the ratio of the number of core materials in which the distance between the surface of the base material particle and the surface of the core material exceeds 5 nm is more than 80% and not more than 100%. The electroconductive particle of Claim 1 or 2.
The conductive particle according to any one of claims 1 to 3, wherein the metal element contained most in the core substance and the metal element contained most in the conductive layer are the same.
The conductive layer comprises a first conductive layer covering the base particles, and a second conductive layer covering the first conductive layer and the core substance,
The core material is disposed on a surface of the first conductive layer and embedded in the second conductive layer;
The second conductive layer has a plurality of protrusions on an outer surface;
The core substance is disposed inside the protrusion of the second conductive layer;
The conductive particle according to any one of claims 1 to 4, wherein the first conductive layer is disposed between the base particle and the core substance.
The conductive particle according to claim 5, wherein the metal element contained most in the core material and the metal element contained most in the second conductive layer are the same.
The conductive particles according to any one of claims 1 to 4, wherein the conductive layer is a single conductive layer.
The conductive particle according to any one of claims 1 to 7, wherein the core substance is a metal particle.
The conductive particle according to any one of claims 1 to 8, further comprising an insulating material attached to a surface of the conductive layer.
A conductive material comprising the conductive particles according to any one of claims 1 to 9 and a binder resin.
A first connection target member;
A second connection target member;
A connecting portion connecting the first and second connection target members;
A connection structure in which the connection portion is formed of the conductive particles according to any one of claims 1 to 9, or is formed of a conductive material containing the conductive particles and a binder resin.