KR20130122730A - Conductive particles, anisotropic conductive material and connection structure - Google Patents

Abstract

This invention provides the electroconductive particle which is hard to produce a big crack in a conductive layer even if a large force is provided to electroconductive particle, and the anisotropic conductive material and bonded structure which used the said electroconductive particle. The electroconductive particle 1 which concerns on this invention is equipped with the substrate particle 2 and the copper- tin layer 3 provided on the surface 2a of the said substrate particle 2. The copper-tin layer 3 comprises an alloy of copper and tin. Content of copper in the copper- tin layer 3 whole is more than 20 weight% and 75 weight% or less, and content of tin is 25 weight% or more and less than 80 weight%. The anisotropic conductive material which concerns on this invention contains electroconductive particle 1 and binder resin. The connection structure which concerns on this invention is equipped with the 1st connection object member, the 2nd connection object member, and the connection part which connects the said 1st, 2nd connection object member. The said connection part is formed of the anisotropic electrically-conductive material containing electroconductive particle 1 or electroconductive particle 1.

Description

Electroconductive particle, anisotropic conductive material, and bonded structure {CONDUCTIVE PARTICLES, ANISOTROPIC CONDUCTIVE MATERIAL AND CONNECTION STRUCTURE}

This invention relates to the electroconductive particle which can be used for the connection between electrodes, for example, More specifically, it is related with the electroconductive particle which has a substrate particle and the conductive layer provided on the surface of the said substrate particle. Moreover, this invention relates to the anisotropic conductive material and bonded structure which used the said electroconductive particle.

Anisotropic conductive materials, such as an anisotropic conductive paste and an anisotropic conductive film, are widely known. In the said anisotropic conductive material, electroconductive particle is disperse | distributed in binder resin.

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

As an example of the electroconductive particle used for the said anisotropic conductive material, the following patent document 1 discloses the electroconductive particle provided with resin particle and the copper layer provided on the surface of the said resin particle. In patent document 1, although such electroconductive particle is not disclosed by the specific example, it is described that favorable electrical connection is obtained in the connection of the opposing circuit.

As is being used abundantly in the Example of patent document 1, the electroconductive particle which has a nickel layer conventionally is mainstream. However, nickel itself has a problem of high electrical resistance and difficulty in lowering connection resistance. On the other hand, since copper has low electrical resistance, it is advantageous to apply copper as a conductive layer of electroconductive particle from a viewpoint of lowering connection resistance. However, copper has soft properties compared to nickel and the like. Therefore, when the conductive layer formed of copper is too soft and a large force is applied to the conductive particles, cracks are likely to occur in the conductive layer. For example, when a connection structure is obtained using conventional electroconductive particle for the connection between electrodes, a big crack may generate | occur | produce in a conductive layer. Therefore, there may be a case where the electrodes cannot be reliably connected.

Moreover, as electroconductive particle which has a conductive layer containing copper, the electroconductive particle which has the alloy film of the tin-silver-copper ternary system is disclosed by following patent document 2. In the Example of patent document 2, in order to obtain electroconductive particle, a tin plating film is formed in the surface of a copper metal particle, a silver plating film is formed, and then it heats at 240 degreeC or more, and a metal heat diffusion is produced, and tin-silver- A copper ternary alloy film is formed.

In the said patent document 2, the content rate of the composition in the ternary alloy film of tin-silver-copper states that 80-99.8 weight% of tin, 0.1-10 weight% of silver, and 0.1-10 weight% of copper are described. It is. Specifically, in all the examples of the said patent document 2, the alloy film which is 96.5 weight% of tin, 3 weight% of silver, and 0.5 weight% of copper is formed. Since these electroconductive particles contain relatively few silver and copper, but contain comparatively many tin, melting | fusing point of the tin-silver-copper ternary alloy film becomes comparatively low. Since the anisotropic conductive material containing the electroconductive particle which has a conductive layer with low melting | fusing point generate | occur | produces the flow of a conductive layer by heat at the time of the heat press bonding for forming a bonded structure, and may flow out more than necessary, it contacts with an electrode. The thickness of the electrically conductive layer which exists is too thin, and connection defect may arise.

Japanese Patent Laid-Open No. 2003-323813 WO2006 / 080289 A1

The objective of this invention is providing the electroconductive particle which is hard to produce a big crack in a conductive layer even if a large force is given to electroconductive particle, and the anisotropic conductive material and bonded structure which used the said electroconductive particle.

In addition, a limited object of the present invention is a conductive particle having a high melting point of the copper-tin layer and capable of suppressing excessive thermal deformation and outflow of the copper-tin layer at the time of heat pressing for forming a bonded structure, and the conductive particles. It is to provide an anisotropic conductive material and a bonded structure using.

According to a broad aspect of the present invention, there is provided a substrate particle and a copper-tin layer comprising copper and tin provided on a surface of the substrate particle, the copper-tin layer comprising an alloy of copper and tin, The electroconductive particle whose content of copper in the whole copper- tin layer is more than 20 weight% and 75 weight% or less, and content of tin is 25 weight% or more and less than 80 weight% is provided.

In a specific aspect of the electroconductive particle which concerns on this invention, melting | fusing point of the said copper- tin layer is 550 degreeC or more.

In certain specific aspects of the electroconductive particle which concerns on this invention, content of copper in the said copper- tin layer whole is 40 weight% or more and 60 weight% or less, and content of tin is 40 weight% or more and 60 weight% or less.

In certain specific aspects of the electroconductive particle which concerns on this invention, the said electroconductive particle has a processus | protrusion on the surface.

In another specific situation of the electroconductive particle which concerns on this invention, the insulating substance arrange | positioned on the surface of the said copper- tin layer is provided.

In another specific situation of the electroconductive particle which concerns on this invention, the said insulating substance is insulating particle.

The anisotropic conductive material which concerns on this invention contains the electroconductive particle comprised by this invention, and binder resin.

The bonded structure which concerns on this invention is equipped with the connection part which connects the 1st connection object member, the 2nd connection object member, and the said 1st, 2nd connection object member, The said electroconductive particle comprised by the said connection part according to this invention. It is formed of or is formed of the anisotropic conductive material containing the said electroconductive particle and binder resin.

As for the electroconductive particle which concerns on this invention, the copper- tin layer containing copper and tin is provided on the surface of a substrate particle, The said copper- tin layer contains the alloy of copper and tin, The said copper- tin layer whole Since content of copper in is more than 20 weight% and 75 weight% or less, and content of tin is 25 weight% or more and less than 80 weight%, even if a large force is given to electroconductive particle, a big crack hardly arises in a conductive layer.

1 is a cross-sectional view showing conductive particles according to a first embodiment of the present invention.
It is sectional drawing which shows the electroconductive particle concerning the 2nd Embodiment of this invention.
It is a front sectional drawing which shows typically the bonded structure using the electroconductive particle which concerns on 1st Embodiment of this invention.
It is sectional drawing for demonstrating the method of obtaining the electroconductive particle shown in FIG.
It is sectional drawing which shows the electroconductive particle which concerns on 3rd Embodiment of this invention.
It is sectional drawing which shows the electroconductive particle concerning the 4th Embodiment of this invention.

Hereinafter, the present invention will be described with reference to specific embodiments and examples of the present invention, with reference to the drawings.

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

The electroconductive particle 1 shown in FIG. 1 is equipped with the substrate particle 2 and the copper- tin layer 3 provided on the surface 2a of the said substrate particle 2. The copper-tin layer 3 is a conductive layer (first conductive layer). The electroconductive particle 1 may further be equipped with the insulating substance arrange | positioned on the surface 3a of the copper- tin layer 3. In addition, another conductive layer (second conductive layer) such as a palladium layer may be laminated on the surface 3a of the copper-tin layer 3. The insulating material may be indirectly disposed on the surface 3a of the copper-tin layer 3 via another conductive layer such as a palladium layer.

The copper-tin layer 3 comprises an alloy of copper and tin. In the present embodiment, the copper-tin layer 3 is a copper-tin alloy layer. Some areas of the copper-tin layer may not contain tin, and some areas of the copper-tin layer may not contain copper. For example, the inner part of the copper-tin layer may contain only copper, and the outer part of the copper-tin layer may contain only tin. Content of copper in the copper- tin layer 3 whole is more than 20 weight% and 75 weight% or less, and content of tin is 25 weight% or more and less than 80 weight%.

The characteristic of this embodiment is that the copper- tin layer 3 provided on the surface 2a of the substrate particle 2 contains the alloy of copper and tin, and content of copper in the copper-tin layer 3 whole. It is more than 20 weight% and 75 weight% or less, and content of tin is 25 weight% or more and less than 80 weight%. Even if a large force is applied to the conductive layer by the formation of such a copper-tin layer 3, a large crack is unlikely to occur in the conductive layer. This is considered to be because the hardness of the copper-tin layer 3 increases suitably by alloying copper and tin. Therefore, when the connection structure is obtained using the electroconductive particle 1 for the connection between electrodes, a big crack hardly arises in a conductive layer, and the conduction reliability between electrodes can be improved. In addition, the said big crack means the crack of the grade in which a conductive layer peels and falls out from a substrate particle, and the connection defect between electrodes arises. In addition, since the copper-tin layer 3 contains a relatively large amount of copper, the connection resistance between the electrodes can be lowered.

In addition, copper has higher conductivity than nickel. Therefore, in order to improve conductivity, it is preferable to use copper rather than nickel. In the present invention, copper is used for the conductive layer. In addition, in the present invention, unlike a conductive material generally called solder, copper is used relatively much.

Content of copper in the copper- tin layer 3 whole becomes like this. Preferably it is 30 weight% or more, More preferably, it is 35 weight% or more, More preferably, it is 40 weight% or more, Preferably it is 70 weight% or less. Content of tin in the copper- tin layer 3 whole becomes like this. Preferably it is 30 weight% or more, Preferably it is 70 weight% or less, More preferably, it is 65 weight% or less, More preferably, it is 60 weight% or less.

It is preferable that content of copper in the copper- tin layer 3 whole is 30 weight% or more and 70 weight% or less, and content of tin is 30 weight% or more and 70 weight% or less. It is more preferable that content of copper in the whole copper- tin layer 3 is 35 weight% or more and 65 weight% or less, and content of tin is 35 weight% or more and 65 weight% or less. It is more preferable that content of copper in the whole copper- tin layer 3 is 40 weight% or more and 60 weight% or less, and content of tin is 40 weight% or more and 60 weight% or less.

In particular, when the content of copper in the entire copper-tin layer 3 is 40% by weight or more and 60% by weight or less, and the content of tin is 40% by weight or more and 60% by weight or less, even when a large force is applied to the conductive layer, the conductive Larger cracks in the layer are less likely to occur.

In addition, each content of metals, such as copper and tin, in this invention is the value which showed the quantity of copper or tin with respect to the total weight of the metal of a conductive layer in weight%. As the measuring method, the metal of the conductive layer is dissolved with aqua regia, and the solution in which the metal is dissolved is measured by using ICP (inductively coupled plasma, Horiba Seisakusho Co., Ltd. "ULTIMA2") to obtain the conductive layer from the metal ion concentration obtained. The measuring method of calculating the weight of a metal and the quantity of each metal is mentioned.

The electroconductive particle 1 shown in FIG. 1 can be obtained using the electroconductive particle shown in FIG. 4, for example.

The copper layer 52 containing copper is formed on the surface 2a of the substrate particle 2. Next, the tin layer 53 containing tin is formed on the surface 52a of the copper layer 52, and the electroconductive particle 51 before a heating is obtained. Next, the electroconductive particle 51 is heated, and copper and tin are alloyed. In order to alloy alloy copper and tin efficiently, the temperature of the said heating becomes like this. Preferably it is 150 degreeC or more, More preferably, it is 180 degreeC or more, Preferably it is 250 degrees C or less, More preferably, it is 230 degrees C or less. In order to efficiently alloy copper and tin, it is especially preferable to heat electroconductive particle at 200-220 degreeC for 18 to 24 hours. The copper-tin layer 3 is preferably a copper-tin layer heat-treated at 150 ° C. or higher so as to contain an alloy of copper and tin.

In the electroconductive particle 51, content of copper and content of tin in the copper- tin layer 3 whole can be adjusted by adjusting each thickness of the copper layer 52 and the tin layer 53.

It is preferable that the electroconductive particle concerning this invention is electroconductive particle obtained by heating the electroconductive particle in which the copper layer is provided on the surface of a substrate particle, and the tin layer is provided on the surface of the said copper layer.

It is sectional drawing which shows the electroconductive particle concerning the 2nd Embodiment of this invention.

The electroconductive particle 11 shown in FIG. 2 is equipped with the substrate particle 2 and the copper- tin layer 12 provided on the surface 2a of the said substrate particle 2. The copper-tin layer 12 is a conductive layer. The electroconductive particle 11 is equipped with the some core substance 13 in the surface 2a of the substrate particle 2. The copper-tin layer 12 which is a conductive layer coat | covers the core substance 13. The electroconductive particle 11 has the some processus | protrusion 14 in the surface 11a by covering the core substance 13 with the conductive layer. The electroconductive particle 11 has the some processus | protrusion 14 in the surface 12a of the outer side of the copper- tin layer 12. As shown in FIG. The projection 14 is formed on the surface 12a of the copper-tin layer 12. The surface 12a of the copper-tin layer 12 is raised by the core substance 13, and the protrusion 14 is formed. The core substance 13 is arrange | positioned inside the protrusion 14. Another conductive layer such as a palladium layer may be laminated on the surface 12a of the copper-tin layer 12.

The electroconductive particle 11 is equipped with the insulating particle 15 arrange | positioned on the surface 12a of the copper- tin layer 12. As shown in FIG. The insulating particle 15 is an insulating material. Another conductive layer such as a palladium layer may be present between the copper-tin layer and the insulating particles. In this embodiment, a partial region of the surface 12a of the copper-tin layer 12 is covered with the insulating particles 15. Thus, the electroconductive particle may be equipped with the insulating particle 15 adhering on the surface of conductive layers, such as a copper- tin layer. However, the insulating particle 15 may not necessarily be provided. In addition, an insulating resin layer may be provided instead of the insulating particles 15. Electroconductive particle may be equipped with the insulating resin layer adhering on the surface of conductive layers, such as a copper- tin layer. The surface of conductive layers, such as a copper- tin layer, may be coat | covered with the insulating resin layer. The insulating resin layer is an insulating material.

The electroconductive particle concerning 3rd embodiment of this invention is shown in sectional drawing.

The electroconductive particle 61 shown in FIG. 5 is equipped with the substrate particle 2, the copper- tin layer 3, and the 2nd electroconductive layer 62. As shown in FIG. The second conductive layer 62 is provided on the surface 3a of the copper-tin layer 3 in the conductive particles 1. The second conductive layer 62 is different from the copper-tin layer 3. Moreover, a 2nd electroconductive layer can also be provided on the surface 12a of the copper- tin layer 12 in electroconductive particle 11. In addition, a second conductive layer may be provided on the surface of the substrate particles, and a copper-tin layer may be provided on the second conductive layer. That is, a 2nd conductive layer may be arrange | positioned between a substrate particle and a copper- tin layer.

The electroconductive particle concerning the 4th Embodiment of this invention is shown in sectional drawing in FIG.

The electroconductive particle 71 shown in FIG. 6 is equipped with the substrate particle 2 and the copper- tin layer 72 provided on the surface 2a of the said substrate particle 2. The copper-tin layer 72 has a region which is thinner than the first region and the first region. The copper-tin layer 72 has a thickness variation.

Examples of the substrate particles include resin particles, inorganic particles, organic inorganic hybrid particles, metal particles, and the like.

The base particles are preferably resin particles formed by a resin. When connecting between electrodes, after arrange | positioning electroconductive particle between electrodes, electroconductive particle is generally compressed. If a substrate particle is a resin particle, electroconductive particle will be easy to deform | transform by compression, and the contact area of electroconductive particle and an electrode will become large. Therefore, the conduction | electrical_connection reliability between electrodes can be improved.

Various organic substance is used suitably as resin for forming the said resin particle. As resin for forming the said resin particle, For example, Polyolefin, such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polypropylene, polyisobutylene, polybutadiene; Acrylic resins such as polymethyl methacrylate and polymethyl acrylate; Polyalkylene terephthalate, polysulfone, polycarbonate, polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin and the like are used. For example, by polymerizing one kind or two or more kinds of various polymerizable monomers having an ethylenically unsaturated group, resin particles having any physical properties during compression suitable for the conductive material can be designed and synthesized.

When the said resin particle is obtained by superposing | polymerizing the monomer which has an ethylenically unsaturated group, as a monomer which has the said ethylenically unsaturated group, a non-crosslinkable monomer and a crosslinkable monomer are mentioned.

Examples of the non-crosslinkable monomer include styrene-based monomers such as styrene and? -Methylstyrene; Carboxyl group-containing monomers such as (meth) acrylic acid, maleic acid, and maleic anhydride; (Meth) acrylate, ethyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl Alkyl (meth) acrylates such as acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate and isobornyl (meth) acrylate; (Meth) acrylates such as 2-hydroxyethyl (meth) acrylate, glycerol (meth) acrylate, polyoxyethylene (meth) acrylate and glycidyl (meth) acrylate; Nitrile-containing monomers such as (meth) acrylonitrile; Vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, and propyl vinyl ether; Acid vinyl esters such as vinyl acetate, vinyl butyrate, vinyl laurate and vinyl stearate; 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.

Examples of the crosslinkable monomer include tetramethylolmethane tetra (meth) acrylate, tetramethylol methane tri (meth) acrylate, tetramethylol methane di (meth) acrylate, trimethylolpropane tri (meth) (Meth) acrylate, dipentaerythritol penta (meth) acrylate, glycerol tri (meth) acrylate, glycerol di (meth) acrylate, (poly) ethylene glycol di Polyfunctional (meth) acrylates such as (poly) propylene glycol di (meth) acrylate, (poly) tetramethylene di (meth) acrylate and 1,4-butanediol di (meth) acrylate; (Meth) acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, trimethylolpropane trimethoxysilane, triallyl trimellitate, divinyl benzene, diallyl phthalate, diallyl acrylamide, diallyl ether, , Silane-containing monomers such as vinyltrimethoxysilane, and the like.

The above-mentioned resin particles can be obtained by polymerizing the polymerizable monomer having an ethylenically unsaturated group by a known method. As this method, the method of suspension polymerization in presence of a radical polymerization initiator, and the method of swelling and polymerizing a monomer with a radical polymerization initiator for the non-crosslinked seed particle, etc. are mentioned, for example.

When the said substrate particle is an inorganic particle or organic inorganic hybrid particle, silica, carbon black, etc. are mentioned as an inorganic substance for forming a substrate particle. Although it does not specifically limit as particle | grains formed with the said silica, For example, after hydrolyzing the silicon compound which has two or more hydrolyzable alkoxyl groups, and forming a crosslinked polymer particle, the particle obtained by baking as needed is mentioned. Can be.

When the said substrate particle is a metal particle, silver, copper, nickel, silicon, gold, titanium, etc. are mentioned as a metal for forming the said metal particle. However, it is preferable that the base particles are not metal particles.

It is preferable that the average particle diameter of the said substrate particle exists in the range of 1-100 micrometers. If the average particle diameter of a substrate particle is 1 micrometer or more, the conduction | electrical_connection reliability between electrodes can be improved further. If the average particle diameter of a substrate particle is 100 micrometers or less, the space | interval between electrodes can be narrowed. The minimum with more preferable average particle diameter of a substrate particle is 2 micrometers, a more preferable upper limit is 50 micrometers, a more preferable upper limit is 30 micrometers, and an especially preferable upper limit is 5 micrometers.

The average particle diameter represents a number average particle diameter. The said average particle diameter can be measured, for example using a Coulter counter (made by Beckman Coulter).

The copper-tin layer may have a smooth spherical outer surface, may have a concave-convex shape formed by flaky or plate-shaped metal fragments, and may have a substantially spherical outer surface. The copper-tin layer may be a single conductive layer or a conductive layer in which a plurality of flaky or plate-like conductive materials are laminated.

The Vickers hardness (Hv) of the said copper- tin layer becomes like this. Preferably it is 100 or more, Preferably it is 500 or less. If the Vickers hardness of the said copper- tin layer is more than the said minimum and below the said upper limit, the crack of a conductive layer will become less likely to generate | occur | produce further, and the conduction | electrical_connection reliability in a bonded structure will become higher.

Melting | fusing point of the said copper- tin layer becomes like this. Preferably it is 550 degreeC or more, More preferably, it is 600 degreeC or more. The upper limit of the melting point of the copper-tin layer is not particularly limited. If melting | fusing point of the said copper- tin layer is more than the said minimum, excessive heat distortion and outflow of a copper- tin layer can be suppressed.

Melting | fusing point of the said copper- tin layer is the value measured by DSC (differential scanning calorimetry, "EXSTAR X-DSC7000" by the SII company).

The copper-tin layer may have a first region and a second region having a thickness thinner than the first region. The maximum thickness in the said copper- tin layer may exceed 1 time of the minimum thickness, may be 1.1 times or more, may be 1.5 times or more, and may be 2 times or more. When the thickness variation of the said copper- tin layer is large, the binder resin between electroconductive particle and an electrode is effectively excluded when obtaining a bonded structure using the anisotropic conductive material containing electroconductive particle and binder resin. Therefore, the conduction | electrical_connection reliability in the bonded structure obtained becomes high. Moreover, it is easy to make thickness fluctuation large by forming the said copper- tin layer by the physical or mechanical hybridization method mentioned later.

It is preferable that the average thickness of the said copper- tin layer exists in the range of 10-1000 nm. The minimum with more preferable average thickness of a copper- tin layer is 20 nm, a more preferable minimum is 50 nm, a more preferable upper limit is 800 nm, a more preferable upper limit is 500 nm, and a particularly preferable upper limit is 300 nm. If the average thickness of a copper- tin layer is more than the said minimum, the electroconductivity of electroconductive particle can further be improved. If the average thickness of a copper-tin layer is below the said upper limit, the difference of the thermal expansion rate of a substrate particle and a copper- tin layer will become small, and a copper-tin layer will become difficult to peel from a substrate particle.

As a method of forming a copper layer on the surface of a substrate particle in order to form the said copper- tin layer, the method of forming a copper layer by electroless plating, the method of forming a copper layer by electroplating, etc. are mentioned. have. In order to form a copper-tin layer, for example, as a method of forming a tin layer on the surface of a copper layer, the method of forming a tin layer by electroless plating, the method of forming a tin layer by electroplating, etc. Can be mentioned. In addition, as a preferable method for forming the copper-tin layer, a physical or mechanical forming method may be used, or a physical or mechanical hybridization method may be used. In a physical or mechanical hybridization method, a hybridizer or the like is used.

The said copper- tin layer may contain metal other than copper and tin in the range which does not impair the objective of this invention. Examples of the other metals include gold, silver, palladium, platinum, palladium, zinc, iron, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, thallium, germanium, cadmium, tungsten, silicon and Tin-doped indium oxide (ITO) and the like.

When the copper-tin layer contains the other metal, the content of the other metal in the entire copper-tin layer is preferably 20% by weight or less, more preferably 10% by weight or less, even more preferably 5% by weight. % Or less, Especially preferably, it is 1 weight% or less.

The said electroconductive particle may have a said 2nd conductive layer. The second conductive layer is a conductive layer different from the copper-tin layer. The second conductive layer is preferably a gold layer, a nickel layer, a palladium layer, a copper layer, or an alloy layer containing tin and silver, more preferably a palladium layer or a gold layer, and even more preferably a palladium layer. It is preferable that the said 2nd conductive layer is provided on the surface of a copper- tin layer.

It is preferable that the average thickness of the said 2nd conductive layer is 5 nm or more. When the average thickness of the second conductive layer is 5 nm or more, uniform coating by the second conductive layer is easy. When the second conductive layer is provided on the surface of the copper-tin layer, resistance to the external environment of the conductive particles becomes high, and the copper-tin layer becomes difficult to oxidize, and the copper in the copper-tin layer and the Corrosion of copper by the galvanic reaction between metals (palladium, etc.) constituting the second conductive layer is less likely to occur. Therefore, the electroconductivity of the whole conductive layer in electroconductive particle can be raised further.

It is preferable that the average thickness of the said 2nd conductive layer is 500 nm or less. The cost of electroconductive particle becomes it low that the average thickness of a said 2nd conductive layer is 500 nm or less. In addition, since the amount of the metal constituting the second conductive layer can be reduced, the environmental load can be reduced.

The minimum with preferable average thickness of the said palladium layer is 10 nm, and a more preferable upper limit is 400 nm. If the average thickness of a palladium layer is 10 nm or more, the electroconductivity of electroconductive particle can further be improved.

Like the electroconductive particle 11, it is preferable that the electroconductive particle which concerns on this invention has protrusion on the surface. Vickers hardness (Hv) of the said copper- tin layer becomes like this. Preferably it is 100 or more, and it is preferable that the said electroconductive particle has a processus | protrusion on the surface. It is preferable that electroconductive particle has a processus | protrusion on the surface of a conductive layer, Furthermore, it is preferable to have a processus | protrusion on the surface of a copper- tin layer or the said 2nd electroconductive layer (palladium layer etc.). It is preferable that the said processus | protrusion is plural. The oxide film is formed in the surface of the electrode connected by electroconductive particle in many cases. When electroconductive particle which has a processus | protrusion is used, the said oxide film is effectively excluded by protrusion by arrange | positioning and crimping | bonding electroconductive particle between electrodes. Therefore, the electrode and the conductive layer of the electroconductive particle can be contacted more reliably, and the connection resistance between electrodes can be lowered. Moreover, when electroconductive particle is equipped with an insulating substance (insulating resin layer, insulating particle, etc.) on the surface, or when electroconductive particle is disperse | distributed in resin and used as an anisotropic conductive material, between electroconductive particle and an electrode by protrusion of electroconductive particle The resin of can be effectively excluded. Therefore, the conduction | electrical_connection reliability between electrodes can be improved.

As a method of forming a protrusion on the surface of the said electroconductive particle, after attaching a core substance to the surface of a substrate particle, the method of forming a conductive layer by electroless plating, and a conductive layer by electroless plating on the surface of a substrate particle After the formation, the method of attaching the core material and forming the conductive layer by electroless plating, etc. may be mentioned.

As a method of adhering a core substance to the surface of the said substrate particle, for example, the conductive substance which becomes a core substance is added to the dispersion liquid of a substrate particle, and a core substance is integrated on the surface of a substrate particle by van der Waals force, for example. And a method for attaching the core material to the surface of the substrate particles by mechanical action such as rotation of the container, by adding a conductive material to be a core material to the container into which the substrate particles are placed. Especially, since the quantity of the core substance to adhere is easy to control, the method of accumulating and sticking a core substance to the surface of the substrate particle in a dispersion liquid is preferable.

As an electroconductive substance which comprises the said core substance, electroconductive nonmetals, such as a metal, an oxide of a metal, graphite, an electroconductive polymer, etc. are mentioned, for example. Polyacetylene etc. are mentioned as a conductive polymer. Especially, since electroconductivity can be improved, a metal is preferable.

Examples of the metal 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. And alloys composed of two or more metals such as alloys, tin-copper alloys, tin-silver alloys, and tin-lead-silver alloys. Especially, 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. Examples of the oxide of the metal include alumina, silica and zirconia.

Like the electroconductive particle 11, it is preferable that the electroconductive particle which concerns on this invention is equipped with the insulating substance arrange | positioned on the surface of the said copper- tin layer or a palladium layer. In this case, when electroconductive particle is used for the connection between electrodes, the short circuit between adjacent electrodes can be prevented. Specifically, since an insulating substance exists between a some electrode when a some electroconductive particle contacts, it can prevent the short circuit between adjacent electrodes in a horizontal direction instead of between up and down electrodes. In addition, by pressing electroconductive particle with two electrodes at the time of the connection between electrodes, the insulating substance between the electroconductive layer of electroconductive particle and an electrode can be easily excluded. When electroconductive particle has protrusion on the surface of a palladium layer, the insulating substance between the electroconductive layer of electroconductive particle and an electrode can be removed more easily. It is preferable that the said insulating substance is an insulating resin layer or insulating particle. The insulating particles are preferably insulating resin particles.

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

Examples of the polyolefins include polyethylene, ethylene-vinyl acetate copolymers, and ethylene-acrylic acid ester copolymers. As said (meth) acrylate polymer, polymethyl (meth) acrylate, polyethyl (meth) acrylate, polybutyl (meth) acrylate, etc. are mentioned. Examples of the block polymers include polystyrene, styrene-acrylic acid ester copolymers, SB-type styrene-butadiene block copolymers and SBS-type styrene-butadiene block copolymers, and hydrogenated products thereof. Vinyl polymer, a vinyl copolymer, etc. are mentioned as said thermoplastic resin. 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, polyvinylpyrrolidone, polyethylene oxide, methylcellulose and the like. It is more preferable that the electroconductive particle which concerns on this invention is equipped with the insulating particle adhering to the surface of the said conductive layer. In this case, when electroconductive particle is used for the connection between electrodes, the short circuit between the electrodes adjacent to a horizontal direction can be prevented further, and the connection resistance between the connected upper and lower electrodes can further be lowered.

Examples of the method for attaching the insulating particles to the surface of the conductive layer include a chemical method and a physical or mechanical method. As the chemical method, for example, as disclosed in WO2003 / 25955A1, the insulating particles are attached onto the conductive layer of the metal surface particles by hetero-aggregation by van der Waals or electrostatic forces, and chemically bonded as necessary. A method is mentioned. Examples of the physical or mechanical method include spray drying, hybridization, electrostatic deposition, spraying, dipping and vacuum deposition. Especially, since an insulating material is hard to detach | desorb, the method of attaching an insulating material to the surface of the said conductive layer through a chemical bond is preferable.

The particle diameter of the insulating particles is preferably 1/5 or less of the particle diameter of the conductive particles. In this case, the particle diameter of the insulating particles is not too large, and the electrical connection by the conductive layer is more reliably achieved. When the particle diameter of insulating particle is 1/5 or less of the particle diameter of electroconductive particle, when adhering insulating particle by hetero agglomeration method, insulating particle can be adsorb | sucked efficiently on the surface of electroconductive particle. In addition, the particle diameter of the insulating particles is preferably 5 nm or more, more preferably 10 nm or more, preferably 1000 nm or less, and more preferably 500 nm or less. When the particle diameter of the said insulating particle is more than the said minimum, the distance between adjacent electroconductive particles becomes larger than the hopping distance of an electron, and it becomes difficult to produce a leak. When the particle diameter of the said insulating particle is below the said upper limit, the pressure and heat quantity required at the time of thermocompression bonding become small.

It is preferable that CV value of the particle diameter of the said insulating particle is 20% or less. When CV value is 20% or less, the thickness of the coating layer of electroconductive particle becomes uniform, it becomes easy to apply a pressure uniformly at the time of thermocompression bonding between electrodes, and it becomes difficult to produce poor conduction. In addition, the CV value of the said particle diameter is computed by the following formula.

CV value (%) of particle diameter = standard deviation / mean particle diameter * 100 of particle size

The particle size distribution can be measured with a particle size distribution meter or the like before coating the metal surface particles, and can be measured by image analysis or the like of a SEM photograph after coating.

In addition, in order to expose the conductive layer of electroconductive particle, the coverage by an insulating substance becomes like this. Preferably it is 5% or more, Preferably it is 70% or less. The coverage by the said insulating substance is the area of the part coat | covered with the insulating substance which occupies for the whole surface area of metal surface particle | grains. When the said coverage is 5% or more, adjacent electroconductive particles are insulated more reliably by an insulating substance. When the said coverage is 70% or less, it is unnecessary to apply heat and pressure more than necessary at the time of electrode connection, and the performance fall of the binder resin by the excluded insulating material is suppressed.

The insulating particles are not particularly limited, but known inorganic particles and organic polymer particles are applicable. Examples of the inorganic particles include insulating inorganic particles such as alumina, silica, and zirconia.

It is preferable that the said organic polymer particle is a resin particle which (co) polymerized 1 type or 2 or more types of the monomer which has an unsaturated double bond. As a monomer which has the said unsaturated double bond, (meth) acrylic acid; Acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, glycidyl (Poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, trimethylol propane tri (meth) acrylate, glycerol tri (meth) acrylate, (Meth) acrylate esters such as 1,4-butanediol di (meth) acrylate; Vinyl ethers; Vinyl chloride; Styrene compounds such as styrene and divinylbenzene, and acrylonitrile. Especially, (meth) acrylic acid ester is used preferably.

It is preferable that the said insulating particle has a polar functional group in order to make it adhere to the conductive layer of electroconductive particle by hetero aggregation. As said polar functional group, an ammonium group, a sulfonium group, a phosphoric acid group, a hydroxysilyl group, etc. are mentioned, for example. The said polar functional group can be introduce | transduced by copolymerizing the monomer which has the said polar functional group and unsaturated double bond.

Examples of the monomer having an ammonium group include N, N-dimethylaminoethyl methacrylate, N, N-dimethylaminopropylacrylamide, N, N, N-trimethyl-N-2-methacryloyloxyethylammonium chloride and the like. Can be mentioned. As a monomer which has the said sulfonium, methacrylate phenyl dimethyl sulfonium methyl sulfate etc. are mentioned. As a monomer which has the said phosphate group, an acid phospho oxyethyl methacrylate, an acid phospho oxypropyl methacrylate, an acid phospho oxy polyoxyethylene glycol monomethacrylate, and an acid phospho oxy polyoxypropylene glycol monomethacrylate Etc. can be mentioned. As a monomer which has the said hydroxy silyl group, vinyl trihydroxysilane, 3-methacryloxypropyl trihydroxysilane, etc. are mentioned.

As another method of introducing a polar functional group to the surface of the said insulating particle, the method of using the radical initiator which has a polar group as an initiator at the time of superposing | polymerizing the monomer which has the said unsaturated double bond is mentioned. Examples of the radical initiator include 2,2'-azobis {2-methyl-N- [2- (1 -hydroxy-butyl)] - propionamide}, 2,2'- 2-imidazolin-2-yl) propane], 2,2'-azobis (2-amidinopropane) and salts thereof.

(Anisotropic Conductive Material)

The anisotropic conductive material which concerns on this invention contains the electroconductive particle mentioned above and binder resin.

The binder resin is not particularly limited. Generally as said binder resin, insulating resin is used. As said binder resin, a vinyl resin, a thermoplastic resin, curable resin, a thermoplastic block copolymer, an elastomer, etc. are mentioned, for example. Only 1 type may be used for the said binder resin, and 2 or more types may be used together.

As said vinyl resin, a vinyl acetate resin, an acrylic resin, a styrene resin, etc. are mentioned, for example. As said thermoplastic resin, a polyolefin resin, an ethylene-vinyl acetate copolymer, a polyamide resin, etc. are mentioned, for example. As said curable resin, an epoxy resin, a urethane resin, a polyimide resin, an unsaturated polyester resin, etc. are mentioned, for example. The curable resin may be a room temperature curable resin, a thermosetting resin, a photocurable resin, or a moisture curable resin. The said curable resin may be used together with a hardening | curing agent. Examples of the thermoplastic block copolymers include styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, hydrogenated products of styrene-butadiene-styrene block copolymers, and styrene-isoprene-styrene block copolymers. Hydrogenated substance etc. are mentioned. Examples of the elastomer include styrene-butadiene copolymer rubber and acrylonitrile-styrene block copolymer rubber.

The anisotropic conductive material is, in addition to the conductive particles and the binder resin, for example, fillers, extenders, softeners, plasticizers, polymerization catalysts, curing catalysts, colorants, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, lubricants, antistatic agents and Various additives, such as a flame retardant, may be included.

The method of disperse | distributing the said electroconductive particle in the said binder resin can use a conventionally well-known dispersion method, and is not specifically limited. As a method of disperse | distributing the said electroconductive particle in the said binder resin, for example, the said electroconductive particle is added to the said binder resin, and then kneaded and dispersed by a planetary mixer etc., and the said electroconductive particle is homogeneous in water or an organic solvent. Uniformly dispersed using a group or the like, added to the binder resin, kneaded with a planetary mixer or the like, and diluted with water or an organic solvent, and then the conductive particles are added. And a method of kneading and dispersing with a planetary mixer or the like.

The anisotropic conductive material which concerns on this invention can be used as an anisotropic conductive paste and an anisotropic conductive film. When the anisotropic conductive material which concerns on this invention is an anisotropic conductive film, the film which does not contain electroconductive particle may be laminated | stacked on the anisotropic conductive film containing electroconductive particle.

It is preferable that the said anisotropic electrically-conductive material is an anisotropic electrically conductive paste from a viewpoint of suppressing generation | occurrence | production of a space | gap in a connection part in a connection structure, and further improving conduction reliability. It is preferable that the said anisotropic conductive material is an anisotropic conductive paste, and is an anisotropic conductive material coated on the upper surface of a connection object member in a paste-like state.

It is preferable that content of the said binder resin is in the range of 10-99.99 weight% in 100 weight% of said anisotropic conductive materials. The minimum with more preferable content of the said binder resin is 30 weight%, a further more preferable minimum is 50 weight%, an especially preferable minimum is 70 weight%, and a more preferable upper limit is 99.9 weight%. When content of the said binder resin satisfy | fills the said minimum and upper limit, electroconductive particle can be arrange | positioned efficiently between electrodes, and the conduction | electrical_connection reliability between electrodes can be improved further.

It is preferable that content of the said electroconductive particle exists in the range of 0.01-20 weight% in 100 weight% of said anisotropic conductive materials. The minimum with more preferable content of the said electroconductive particle is 0.1 weight%, and a more preferable upper limit is 10 weight%. When content of the said electroconductive particle satisfy | fills the said minimum and upper limit, the conduction | electrical_connection reliability between electrodes can be improved further.

(Connection structure)

A connection structure can be obtained by connecting a connection object member using the electroconductive particle which concerns on this invention, or the anisotropic conductive material containing the said electroconductive particle and binder resin.

The said bonded structure is equipped with the 1st connection object member, the 2nd connection object member, and the connection part which connects the said 1st, 2nd connection object member, The said connection part is formed of the electroconductive particle of this invention, Or it is preferable that it is a bonded structure formed of the anisotropic conductive material containing the said electroconductive particle and binder resin. When electroconductive particle is used, connection part itself is electroconductive particle. That is, the 1st, 2nd connection object member is connected by electroconductive particle.

The bonded structure using the electroconductive particle which concerns on one Embodiment of this invention in FIG. 3 is typically shown in front sectional drawing.

The connection structure 21 shown in FIG. 3 connects the 1st connection object member 22, the 2nd connection object member 23, and the 1st, 2nd connection object members 22, 23, It has a connecting portion 24. The connection part 24 is formed by hardening the anisotropic electrically-conductive material containing electroconductive particle 1. In addition, in FIG. 3, the electroconductive particle 1 is shown schematically for convenience of illustration. Instead of the electroconductive particle 1, electroconductive particle 11, 61, 71 can also be used.

The 1st connection object member 22 has some electrode 22b in the upper surface 22a. The second connection object member 23 has a plurality of electrodes 23b on the lower surface 23a. The electrode 22b and the electrode 23b are electrically connected by the one or some electroconductive particle 1. Therefore, the 1st, 2nd connection object members 22 and 23 are electrically connected by the electroconductive particle 1. As shown in FIG.

The manufacturing method of the connection structure is not particularly limited. As an example of the manufacturing method of a bonded structure, after arrange | positioning the said anisotropic conductive material between a 1st connection object member and a 2nd connection object member, and obtaining a laminated body, the method of heating and pressurizing the said laminated body, etc. are mentioned.

The pressure of the pressurization is about 9.8 x 10 ⁴ to 4.9 x 10 ⁶ Pa. The temperature of the said heating is about 120-220 degreeC. By use of the electroconductive particle which concerns on this invention, even if such a pressure is applied, big crack hardly arises in a copper- tin layer. Therefore, the conduction | electrical_connection reliability between electrodes can be improved.

Specifically as said connection object member, electronic components, such as a semiconductor chip, a capacitor | condenser, and a diode, and circuit boards, such as a printed circuit board, a flexible printed circuit board, and a glass substrate, etc. are mentioned.

As an electrode provided in the said connection object member, 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, are mentioned. When the said connection object member is a flexible printed circuit board, it is preferable that the said electrode is 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 from aluminum may be sufficient, and the electrode in which the aluminum layer was laminated | stacked on the surface of the metal oxide layer may be sufficient. Examples of the metal oxides include indium oxide doped with a trivalent metal element, zinc oxide doped with a trivalent metal element, and the like. Sn, Al, Ga, etc. are mentioned as said trivalent metal element.

Electroconductive particle can also be used as a conductive material for making the electrical connection between the upper and lower board | substrates which comprise a liquid crystal display element, taking the other use form of the electroconductive particle which concerns on this invention, for example. The electroconductive particle is mixed with a thermosetting resin or curable resin for thermal UV combined use, and it disperse | distributes, apply | coats in a dot form on one board | substrate, and combines and disperse | distributes electroconductive particle in peripheral sealing agent, and apply | coats in linear form, There exists a method of using both the sealing seal and the electrical connection of an upper and lower board | substrate. In any of these usage forms, the electroconductive particle which concerns on this invention is applicable. Moreover, since the electroconductive particle which concerns on this invention is provided in the surface of a substrate particle, the electrically conductive connection is possible, without damaging a transparent substrate etc. by the outstanding elasticity of a substrate particle.

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples. This invention is not limited only to a following example.

(Example 1)

(1) resin particle formation process

70 parts by weight of divinylbenzene, 30 parts by weight of trimethylolpropane trimethacrylate, and benzoyl peroxide in 800 parts by weight of an aqueous solution containing 3% by weight of polyvinyl alcohol ("GH-20" manufactured by Nippon Kosei Chemical Co., Ltd.) 2 parts by weight were added, and stirred and mixed. It heated to 80 degreeC, stirring in nitrogen atmosphere, and reacted for 15 hours, and obtained resin particle.

After wash | cleaning the obtained resin particle with distilled water and methanol, classification operation was performed and the resin particle which is 4.1 micrometers of average particle diameters, and 5.0% of a variation coefficient was obtained. Hereinafter, it may describe as resin particle A.

(2) electroless copper plating process

It washed with water, after etching the obtained resin particle A10g. Next, palladium sulfate was added to the resin particles, and palladium ions were adsorbed onto the resin particles.

Subsequently, the resin particle which palladium ion adsorbed was added to the aqueous solution containing 0.5 weight% of dimethylamine borane, and palladium was activated. 500 mL of distilled water was added to this resin particle, and the particle suspension was obtained.

It also contains 40 g / L copper sulfate (pentahydrate), 100 g / L ethylenediaminetetraacetic acid (EDTA), 50 g / L sodium gluconate, and 25 g / L formaldehyde. An electroless plating solution adjusted to 10.5 was prepared. The electroless plating solution was gradually added to the particle suspension, and electroless copper plating was performed while stirring at 50 ° C. Thus, the copper plating particle in which the copper layer (thickness about 40 nm) was provided on the surface was obtained.

(3) electroless tin plating process

A solution containing 5 g of tin chloride and 1000 mL of ion exchanged water was prepared, and 15 g of the obtained copper plated particles were mixed to obtain an aqueous suspension. 30 g of thiourea and 80 g of tartaric acid were added to this aqueous suspension to obtain a plating solution. This plating liquid was made into 60 degreeC of bath temperatures, and it was made to react for 20 minutes. Further, 20 g of tin chloride, 40 g of citric acid, and 30 g of sodium hydroxide were further added to the plating solution, and the reaction was carried out at a bath temperature of 60 ° C. for 20 minutes to obtain particles having a tin layer (thickness of about 72 nm) provided on the surface of the copper layer. .

(4) alloying process

The obtained tin layer heated the particle | grains provided on the surface of a copper layer at 220 degreeC for 20 hours. After heating, the copper and tin layers were alloyed. In this way, the copper-tin layer (about 100 nm in thickness) was provided on the surface of the resin particle, and the said copper-tin layer obtained electroconductive particle containing the alloy of copper and tin. In the obtained electroconductive particle, as a result of evaluating content of copper and tin contained in the whole copper- tin layer, content of copper was 40 weight% and content of tin was 60 weight%.

(Example 2)

The surface of the resin particle was carried out similarly to Example 1 except having changed the thickness of the copper layer to about 50 nm in the electroless copper plating process, and changing the thickness of the tin layer to about 60 nm in the electroless tin plating process. The copper-tin layer (about 100 nm in thickness) was provided in the phase, and the said copper-tin layer obtained electroconductive particle containing the alloy of copper and tin. As a result of evaluating content of the copper and tin contained in the whole copper- tin layer in the obtained electroconductive particle, content of copper was 50 weight% and content of tin was 50 weight%.

(Example 3)

The surface of the resin particle was carried out similarly to Example 1 except having changed the thickness of the copper layer to about 60 nm in the electroless copper plating process, and changing the thickness of the tin layer to about 48 nm in the electroless tin plating process. The copper-tin layer (about 100 nm in thickness) was provided in the phase, and the said copper-tin layer obtained electroconductive particle containing the alloy of copper and tin. As a result of evaluating content of the copper and tin contained in the whole copper- tin layer in the obtained electroconductive particle, content of copper was 60 weight% and content of tin was 40 weight%.

(Example 4)

(1) Core material deposition process

After 10 g of the resin particles A obtained in Example 1 were etched, they were washed with water. Next, palladium sulfate was added to the resin particles, and palladium ions were adsorbed onto the resin particles.

The resin particles with palladium were stirred for 3 minutes in 300 mL of ion-exchanged water, and dispersed to obtain a dispersion. Subsequently, 1 g of a metal nickel particle slurry ("2020SUS" by Mitsui Kinzo Co., Ltd., 200 nm of average particle diameters) was added to the said dispersion liquid over 3 minutes, and the resin particle with a core substance was obtained.

(2) Preparation of conductive particles

A copper-tin layer was formed on the surface of the resin particles by carrying out an electroless copper plating process, an electroless tin plating process and an alloying process in the same manner as in Example 1 except that the resin particles with a core substance were used. The said copper- tin layer obtained electroconductive particle containing the alloy of copper and tin. The obtained electroconductive particle had protrusion on the surface of a copper- tin layer. In the obtained electroconductive particle, as a result of evaluating content of copper and tin contained in the whole copper- tin layer, content of copper was 40 weight% and content of tin was 60 weight%. In addition, when determining content of copper and tin, nickel contained as a core substance is excluded.

(Example 5)

Copolymerizable resin particles of 1,4-butanediol diacrylate and tetramethylol methane tetraacrylate (1,4-butanediol diacrylate: tetramethylol methane tetraacrylate = 95% by weight: 5% by weight The electroconductive particle was obtained like Example 4 except having changed to the resin particle B below. The obtained electroconductive particle had protrusion on the surface of a copper- tin layer.

(Example 6)

(1) Preparation of insulating resin particles

In a 1000 mL separate flask equipped with a four-neck detachable cover, agitating vanes, three-way coke, cooling tube and temperature probe, 100 mmol of methyl methacrylate and N, N, N-trimethyl-N-2-methacryl A monomer composition comprising 1 mmol of monooxyethylammonium chloride and 1 mmol of 2,2'-azobis (2-amidinopropane) dihydrochloride was added to the ion-exchanged water so that the solid content was 5% by weight. It stirred at rpm and superposed | polymerized at 70 degreeC for 24 hours in nitrogen atmosphere. After completion | finish of reaction, it freeze-dried and had the ammonium group on the surface, and obtained insulating resin particle which is an average particle diameter of 220 nm, and CV value 10%.

The insulating resin particles were dispersed in ion-exchanged water under ultrasonic irradiation to obtain a 10% by weight aqueous dispersion of the insulating resin particles.

10 g of the electroconductive particle obtained in Example 5 was disperse | distributed to 500 mL of ion-exchange water, 4 g of aqueous dispersions of insulating resin particle were added, and it stirred at room temperature for 6 hours. After filtering with a 3 micrometer mesh filter, it wash | cleaned with methanol and dried and obtained electroconductive particle with insulating resin particle.

When observed with the scanning electron microscope (SEM), only one layer of the coating layer by insulating resin particle was formed in the surface of electroconductive particle. The coverage was 30% when the coating area (namely, the projected area of the particle diameter of insulating resin particle) with respect to the area of 2.5 micrometers was computed from the center of electroconductive particle by image analysis.

(Example 7)

Except having changed the resin particle A into the resin particle B, it carried out similarly to Example 1, and obtained electroconductive particle.

(Example 8)

Except having changed the electroconductive particle obtained in Example 5 into the electroconductive particle obtained in Example 1, it carried out similarly to Example 6, and obtained electroconductive particle with insulating resin particle.

(Example 9)

Except having changed the electroconductive particle obtained in Example 5 into the electroconductive particle obtained in Example 4, it carried out similarly to Example 6, and obtained electroconductive particle with insulating resin particle.

(Example 10)

Except having changed the electroconductive particle obtained in Example 5 into the electroconductive particle obtained in Example 7, it carried out similarly to Example 6, and obtained electroconductive particle with insulating resin particle.

(Example 11)

The electroconductive particle obtained in Example 1 was prepared. The process of the following (1) and (2) was implemented using this electroconductive particle.

(1) Electroless Palladium Plating Process

10 g of the obtained copper-plated particles were dispersed in 500 mL of ion-exchanged water by an ultrasonic wave to obtain a particle suspension.

It also contains 4 g / L palladium sulfate (anhydride), 2.4 g / L ethylenediamine, 4.0 g / L hydrazinium sulfate, 3.5 g / L sodium hypophosphite, adjusted to pH 10. An electroless plating solution was prepared. The said electroless plating liquid was added gradually, stirring the said particle suspension at 50 degreeC, and electroless palladium plating was performed. The addition amount of the electroless plating solution was adjusted so that the thickness of the palladium layer was 10 nm. The obtained palladium plated resin particles were washed with distilled water and methanol and then vacuum dried. Thus, the electroconductive particle in which the copper layer was provided in the surface of the resin particle, and the palladium layer was provided in the surface of the copper layer was obtained.

(2) chlorine washing removal process

1 g of the obtained electroconductive particle was disperse | distributed to 1000 mL (specific resistance 18 M (ohm)) of distilled water, it put in the autoclave with a stirrer, and it stirred and wash | cleaned at 121 degreeC for 10 hours under pressure of 0.1 MPa. Then, it filtered and dried.

In this way, a copper-tin layer (about 100 nm thick) is provided on the surface of the resin particles, and the copper-tin layer contains an alloy of copper and tin, and a palladium layer (on the surface of the copper-tin layer) Electroconductive particle in which thickness (10 nm) was provided was obtained.

(Example 12)

Resin particle A obtained in Example 1 was prepared. Moreover, copper powder (particle size 3.0-7.0 micrometers) and tin powder (particle size 3.0-7.0 micrometers) were prepared.

Using resin particle A, copper powder, and tin powder, a copper-tin layer (thickness 100 nm) on the surface of the resin particles by physical / mechanical hybridization method using a hybridizer (manufactured by Seisakusho Co., Ltd.) Particles with

Next, the particle | grains which have a copper- tin layer on the surface of the obtained resin particle were heated at 220 degreeC for 20 hours. After the heating, the copper and tin layers were alloyed. In this way, the copper-tin layer (100 nm in thickness) was provided on the surface of the resin particle, and the said copper-tin layer obtained electroconductive particle containing the alloy of copper and tin. In the obtained electroconductive particle, as a result of evaluating content of copper and tin contained in the whole copper- tin layer, content of copper was 40 weight% and content of tin was 60 weight%. The maximum thickness in the said copper- tin layer was 2 times or more of the minimum thickness.

(Example 13)

Resin particle A used in Example 1 was prepared. Furthermore, copper tin alloy powder (content 40 weight% of copper, content 60 weight% of tin, and particle diameters 3.0-7.0 micrometers) was prepared.

Copper-tin layer (thickness 100 nm) on the surface of a resin particle by physical / mechanical hybridization method using the hybridizer (made by Seisakusho Corp.) using resin particle A and copper tin alloy powder. Particles having were obtained.

As a result of evaluating content of the copper and tin contained in the whole copper- tin layer in the obtained electroconductive particle, content of copper was 40 weight% and content of tin was 60 weight%. The maximum thickness in the said copper- tin layer was 2 times or more of the minimum thickness.

(Comparative Example 1)

Resin particle A obtained in Example 1 was prepared. After 10 g of this resin particle A was etched, it was washed with water. Next, palladium sulfate was added to the resin particles, and palladium ions were adsorbed onto the resin particles.

Subsequently, the resin particle which palladium ion adsorbed was added to the aqueous solution containing 0.5 weight% of dimethylamine borane, and palladium was activated. 500 mL of distilled water was added to this resin particle, and the particle suspension was obtained.

It also contains 40 g / L copper sulfate (pentahydrate), 100 g / L ethylenediaminetetraacetic acid (EDTA), 50 g / L sodium gluconate, and 25 g / L formaldehyde. An electroless plating solution adjusted to 10.5 was prepared. The electroless plating solution was gradually added to the particle suspension, and electroless copper plating was performed while stirring at 50 ° C. Thus, the copper plating particle (electroconductive particle) with which the copper layer (thickness 100nm) was provided on the surface was obtained. In Comparative Example 1, a tin layer was not provided on the surface of the copper layer.

(Comparative Example 2)

The tin layer (about 72 nm thick) obtained after the electroless tin plating process of Example 1 made the particle | grains provided on the surface of a copper layer (thickness about 40 nm) the electroconductive particle. In Comparative Example 2, the alloying step was not performed.

(Comparative Example 3)

The surface of the resin particle was carried out similarly to Example 1 except having changed the thickness of the copper layer to about 80 nm in the electroless copper plating process, and changing the thickness of the tin layer to about 20 nm in the electroless tin plating process. A copper-tin layer (thickness 100 nm) was provided on the phase, and the copper-tin layer obtained electroconductive particle containing the alloy of copper and tin. As a result of evaluating content of the copper and tin contained in the whole copper- tin layer in the obtained electroconductive particle, content of copper was 80 weight% and content of tin was 20 weight%.

(Comparative Example 4)

The surface of the resin particle was the same as in Example 1 except that the thickness of the copper layer was changed to about 14 nm in the electroless copper plating process, and the thickness of the tin layer was changed to about 96 nm in the electroless tin plating process. The copper-tin layer (about 100 nm in thickness) was provided in the phase, and the said copper-tin layer obtained electroconductive particle containing the alloy of copper and tin. As a result of evaluating content of the copper and tin contained in the whole copper- tin layer in the obtained electroconductive particle, content of copper was 15 weight% and content of tin was 85 weight%.

(Example 14)

The surface of the resin particle was carried out similarly to Example 1 except having changed the thickness of the copper layer to about 30 nm in the electroless copper plating process, and changing the thickness of the tin layer to about 84 nm in the electroless tin plating process. The copper-tin layer (about 100 nm in thickness) was provided in the phase, and the said copper-tin layer obtained electroconductive particle containing the alloy of copper and tin. As a result of evaluating content of the copper and tin contained in the whole copper- tin layer in the obtained electroconductive particle, content of copper was 30 weight% and content of tin was 70 weight%.

(evaluation)

(1) cracks in the conductive layer

Two substrates on which a copper electrode having an L / S of 100 µm / 100 µm were formed. Furthermore, the anisotropic conductive paste containing 10 weight part of electroconductive particle, 85 weight part of epoxy resins ("Strut bond XN-5A" by Mitsui Chemicals, Inc.) as binder resin, and 5 weight part of imidazole-type hardening | curing agents were prepared. .

After applying an anisotropic conductive paste on the upper surface of the substrate so that the conductive particles contacted the copper electrode, another substrate was laminated so that the copper electrode contacted the conductive particles, and pressed under a pressure of 3 MPa to obtain a laminate. Then, the anisotropic conductive paste was hardened and the bonded structure was obtained by heating a laminated body at 180 degreeC for 1 minute.

In the obtained bonded structure, whether the crack was in the conductive layer of electroconductive particle was evaluated. The crack of the conductive layer was determined based on the following criteria.

[Criterion for Determination of Crack in Conductive Layer]

(Circle): There is no big crack in a conductive layer, and resin particle is not exposed.

(Triangle | delta): A big crack exists in the conductive layer, and the resin particle is slightly exposed.

X: A big crack exists in a conductive layer, and resin particle is largely exposed.

(2) conduction reliability

The connection resistance between the opposing electrodes of 100 connection structures obtained by evaluation of said (1) was measured by the four-terminal method, and it was evaluated whether the electrode was electrically conducting, and the conduction reliability was determined on the following reference | standard.

[Criteria for reliability of conduction]

○: all 100 connection structures are conductive

(Triangle | delta): One or two non-conductive number of 100 connection structures

×: 3 or more unconducted numbers among 100 bonded structures

(3) Vickers hardness

The Vickers hardness of the copper-tin layer in the obtained electroconductive particle was measured using the Vickers hardness meter ("DUH-W201" by Shimadzu Corporation). Vickers hardness was determined based on the following criteria.

[Judgement standard of Vickers hardness]

A: Vickers hardness exceeds 500

B: Vickers hardness is 100 or more and 500 or less

C: Vickers hardness less than 100

(4) melting point

0.2-0.5 mg of electroconductive particle was put into the aluminum pan, and it scanned on the conditions of the temperature increase rate of 10 degree-C / min using the T. instrument making "DSC2920", and obtained the heat-flow curve. Melting | fusing point was made into the temperature value which the apex of the peak seen as melting | fusing in this curve shows.

(5) Analysis of metal content

In a glass Erlenmeyer flask, 0.5 g of conductive particles and 20 mL of aqua regia (15 mL of 35% hydrochloric acid solution and 5 mL of 70% nitric acid) were mixed, and allowed to stand for 15 minutes in a 70 ° C hot water bath. After taking out a flask from the water bath, it cooled naturally so that the liquid temperature in a flask might be 40 degrees C or less. After cooling, the acidic solution containing metal ions and resin particles was filtered using a glass funnel and filter paper (Advantech filter paper, No. 5C). Solid-liquid separation was carried out, and 100 mL of the acidic solution containing metal ions was taken out. Then, 1 mL was aliquoted with a micropipette and diluted 100-fold with pure water to obtain a diluent. Using the obtained dilution liquid, it measured by ICP (inductively coupled plasma, Horiba Corporation make "ULTIMA2"), and calculated the weight of the metal of the conductive layer and the amount of each metal from the obtained metal ion concentration.

The results are shown in Table 1 below. In following Table 1, "-" shows the thing which did not evaluate.

One… Conductive particles
2… Substrate particles
2a ... surface
3 ... Copper-Tin Layer
3a ... surface
11 ... Conductive particles
11a ... surface
12... Copper-Tin Layer
12a ... surface
13 ... Core material
14 ... spin
15... Insulating particles
21 ... Connection structure
22... The first connection object member
22a ... Top surface
22b ... electrode
23 ... The second connection object member
23a... if
23b ... electrode
24 ... Connection
51 ... Conductive particles
52 ... Copper layer
52a ... surface
53 ... Tin layer
61... Conductive particles
62 ... Second conductive layer
71 ... Conductive particles
72 ... Copper-Tin Layer

Claims (8)

A base-particle and a copper-tin layer comprising copper and tin provided on the surface of the base-particle,
The copper-tin layer comprises an alloy of copper and tin,
Electroconductive particle whose content of the said copper in the said copper- tin layer whole is more than 20 weight% and 75 weight% or less, and content of tin is 25 weight% or more and less than 80 weight%. Electroconductive particle of Claim 1 whose melting | fusing point of the said copper- tin layer is 550 degreeC or more. Electroconductive particle of Claim 1 or 2 whose content of copper in the said copper- tin layer whole is 40 weight% or more and 60 weight% or less, and content of tin is 40 weight% or more and 60 weight% or less. Electroconductive particle of any one of Claims 1-3 which has a processus | protrusion on the surface. Electroconductive particle of any one of Claims 1-4 provided with the insulating substance arrange | positioned on the surface of the said copper- tin layer. Electroconductive particle of Claim 5 whose said insulating substance is insulating particle. The anisotropic conductive material containing the electroconductive particle of any one of Claims 1-6, and binder resin. It is provided with the 1st connection object member, the 2nd connection object member, and the connection part which connects the said 1st, 2nd connection object member,
The said connection part is formed with the electroconductive particle of any one of Claims 1-6, or the connection structure formed with the anisotropic conductive material containing the said electroconductive particle and binder resin.

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