KR101815336B1 - Conductive particles, anisotropic conductive material and connection structure - Google Patents

Abstract

The present invention provides conductive particles which are less likely to generate large cracks in the conductive layer even when a large force is applied to the conductive particles, and an anisotropic conductive material and a connection structure using the conductive particles. The conductive particles 1 according to the present invention comprise base particles 2 and a copper-tin layer 3 provided on the surface 2a of the base particles 2. The copper-tin layer 3 comprises an alloy of copper and tin. The content of copper in the entire copper-tin layer 3 is more than 20 wt% and not more than 75 wt%, and the content of tin is not less than 25 wt% and less than 80 wt%. The anisotropic conductive material according to the present invention includes conductive particles (1) and a binder resin. A connection structure according to the present invention includes a first connection target member, a second connection target member, and a connection unit connecting the first and second connection target members. The connection portion is formed by the anisotropic conductive material including the conductive particles 1 or the conductive particles 1.

Description

TECHNICAL FIELD [0001] The present invention relates to a conductive particle, an anisotropic conductive material and a connection structure,

The present invention relates to, for example, conductive particles usable for connection between electrodes, and more particularly to conductive particles having base particles and a conductive layer provided on the surface of the base particles. The present invention also relates to an anisotropic conductive material and a connection structure using the conductive particles.

Anisotropic conductive paste such as anisotropic conductive paste and anisotropic conductive film are widely known. In the anisotropic conductive material, the conductive particles are dispersed in the binder resin.

The anisotropic conductive material is used for connection between an IC chip and a flexible printed circuit board and for connecting a circuit board having 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 conductive particles used for the anisotropic conductive material, Patent Document 1 below discloses conductive particles comprising resin particles and a copper layer provided on the surface of the resin particles. Patent Document 1 discloses that such a conductive particle is not disclosed in a specific embodiment but a good electrical connection can be obtained in the connection of opposing circuits.

As is often used in the embodiments described in Patent Document 1, conductive particles having a conventional nickel layer are the mainstream. However, nickel itself has a high electrical resistance, and it is difficult to lower the connection resistance. On the other hand, since copper has a low electrical resistance, it is advantageous to use copper as the conductive layer of the conductive particles from the viewpoint of lowering the connection resistance. However, copper has a soft property as compared with nickel and the like. Therefore, if the conductive layer formed by copper is excessively soft and a large force is applied to the conductive particles, cracks tend to occur in the conductive layer. For example, when a conventional conductive particle is used for connection between electrodes to obtain a connection structure, a large crack may be generated in the conductive layer. Therefore, there is a case that the electrodes can not be reliably connected.

Further, as the conductive particles having a conductive layer containing copper, the following Patent Document 2 discloses conductive particles having a tin-silver-copper ternary alloy coating. In the embodiment of Patent Document 2, a tin plating film is formed on the surface of copper metal particles to obtain conductive particles, a silver plating film is formed on the surface of the tin plating film, Ternary system alloy film of copper is formed.

In Patent Document 2, the content ratio of tin in the tin-silver-copper ternary alloy coating is from 80 to 99.8% by weight of tin, 0.1 to 10% by weight of silver and 0.1 to 10% by weight of copper . Specifically, in all the examples of Patent Document 2, an alloy coating having 96.5% by weight of tin, 3% by weight of silver and 0.5% by weight of copper is formed. Since these conductive particles contain relatively few silver and copper but relatively a large amount of tin, the melting point of the tin-silver-copper ternary alloy coating is relatively low. The anisotropic conductive material containing conductive particles having a conductive layer with a low melting point may flow due to heat during heating and pressing to form a connection structure and may flow out more than necessary, The thickness of the conductive layer is excessively thin, and connection failure may occur.

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

It is an object of the present invention to provide conductive particles which are resistant to generation of large cracks in the conductive layer even when a large force is applied to the conductive particles, and anisotropic conductive materials and connection structures using the conductive particles.

It is a further object of the present invention to provide a conductive particle which has a high melting point of the copper-tin layer and can suppress excessive thermal deformation and outflow of the copper-tin layer during hot pressing to form a connection structure, Anisotropic conductive material and connection structure using the same.

According to a broad aspect of the present invention, there is provided a semiconductor device comprising: base particles; and a copper-tin layer containing copper and tin provided on the surface of the base particles, wherein the copper- tin layer comprises an alloy of copper and tin, The content of copper in the entire copper-tin layer is more than 20% by weight but not more than 75% by weight, and the content of tin is less than 25% by weight and less than 80% by weight.

In a specific aspect of the conductive particles according to the present invention, the melting point of the copper-tin layer is 550 캜 or higher.

In a specific aspect of the conductive particles according to the present invention, the content of copper in the entire copper-tin layer is 40 wt% or more and 60 wt% or less, and the content of tin is 40 wt% or more and 60 wt% or less.

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

In another specific aspect of the conductive particles according to the present invention, an insulating material disposed on the surface of the copper-tin layer is provided.

In another specific aspect of the conductive particles according to the present invention, the insulating material is an insulating particle.

The anisotropic conductive material according to the present invention includes the conductive particles constructed according to the present invention and a binder resin.

A 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, wherein the connection portion is a conductive particle Or formed of an anisotropic conductive material containing the conductive particles and a binder resin.

The conductive particles according to the present invention are characterized in that a copper-tin layer containing copper and tin is provided on the surface of the base particles, the copper-tin layer contains an alloy of copper and tin, , The content of copper is more than 20 wt% and not more than 75 wt%, and the content of tin is not less than 25 wt% and less than 80 wt%, so that even if a large force is applied to the conductive particles, a large crack is hardly generated in the conductive layer.

1 is a cross-sectional view showing conductive particles according to a first embodiment of the present invention.
2 is a cross-sectional view showing conductive particles according to a second embodiment of the present invention.
3 is a front sectional view schematically showing a connection structure using conductive particles according to a first embodiment of the present invention.
4 is a cross-sectional view for explaining a method for obtaining the conductive particles shown in Fig.
5 is a cross-sectional view showing conductive particles according to a third embodiment of the present invention.
6 is a cross-sectional view showing conductive particles according to a fourth embodiment of the present 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 conductive particles 1 shown in Fig. 1 are provided with base particles 2 and a copper-tin layer 3 provided on the surface 2a of the base particles 2. The copper-tin layer 3 is a conductive layer (first conductive layer). The conductive particles 1 may further include an insulating material disposed 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 through another conductive layer such as a palladium layer.

The copper-tin layer 3 comprises an alloy of copper and tin. In this embodiment, the copper-tin layer 3 is a copper-tin alloy layer. Some regions of the copper-tin layer may not contain tin, and some regions of the copper-tin layer may not contain copper. For example, the inner portion of the copper-tin layer may contain only copper, and the outer portion of the copper-tin layer may contain only tin. The content of copper in the entire copper-tin layer 3 is more than 20 wt% and not more than 75 wt%, and the content of tin is not less than 25 wt% and less than 80 wt%.

The feature of this embodiment is that the copper-tin layer 3 provided on the surface 2a of the base particles 2 contains an alloy of copper and tin and the content of copper in the entire copper- Is not less than 20% by weight and not more than 75% by weight, and the content of tin is not less than 25% by weight and less than 80% by weight. Even if a large force is applied to the conductive layer due to the formation of such a copper-tin layer 3, it is difficult for large cracks to be generated in the conductive layer. This is considered to be because the hardness of the copper-tin layer 3 is suitably increased by alloying the copper and tin. Therefore, when the conductive particles 1 are used for connection between the electrodes to obtain a connection structure, large cracks are hardly generated in the conductive layer, and the reliability of conduction between the electrodes can be improved. In addition, the above-mentioned large crack means cracks to such an extent that the conductive layer is peeled off from the base particles and falls off, resulting in connection failure between the electrodes. Further, since the copper-tin layer 3 contains a relatively large amount of copper, the connection resistance between the electrodes can be reduced.

In addition, copper is more conductive than nickel. Therefore, in order to enhance the continuity, it is preferable to use copper rather than nickel. In the present invention, copper is used for the conductive layer. Further, in the present invention, copper is used in a relatively large amount, unlike a conductive material generally called solder.

The content of copper in the entire copper-tin layer 3 is preferably 30% by weight or more, more preferably 35% by weight or more, further preferably 40% by weight or more, and preferably 70% by weight or less. The content of tin in the entire copper-tin layer 3 is preferably 30 wt% or more, preferably 70 wt% or less, more preferably 65 wt% or less, further preferably 60 wt% or less.

The content of copper in the entire copper-tin layer 3 is preferably 30 wt% or more and 70 wt% or less, and the content of tin is preferably 30 wt% or more and 70 wt% or less. It is more preferable that the content of copper in the entire copper-tin layer 3 is 35 wt% or more and 65 wt% or less, and the content of tin is 35 wt% or more and 65 wt% or less. More preferably, the content of copper in the entire copper-tin layer 3 is 40 wt% or more and 60 wt% or less, and the content of tin is 40 wt% or more and 60 wt% or less.

Particularly, when the copper content in the entire copper-tin layer 3 is 40 wt% or more and 60 wt% or less and the tin content is 40 wt% or more and 60 wt% or less, even if a large force is applied to the conductive layer, So that a large crack is hardly generated in the layer.

The content of each of the metals such as copper and tin in the present invention is a value representing the amount of copper or tin in terms of% by weight based on the total weight of the metal of the conductive layer. As the measurement method, the metal of the conductive layer is dissolved in aqua regia, and the solution in which the metal is dissolved is measured using ICP ("ULTIMA2" manufactured by Horiba Seisakusho Co., Ltd.) And a measuring method for calculating the weight of the metal and the amount of each metal.

The conductive particles 1 shown in Fig. 1 can be obtained, for example, by using the conductive particles shown in Fig.

A copper layer 52 containing copper is formed on the surface 2a of the base particle 2. Then, a tin layer 53 containing tin is formed on the surface 52a of the copper layer 52 to obtain the conductive particles 51 before heating. Then, the conductive particles 51 are heated to alloy the copper and tin. In order to alloy copper and tin efficiently, the temperature for the above heating is preferably 150 ° C or more, more preferably 180 ° C or more, preferably 250 ° C or less, more preferably 230 ° C or less. In order to efficiently alloy copper and tin, it is particularly preferable to heat the conductive particles at 200 to 220 DEG C for 18 to 24 hours. The copper-tin layer 3 is preferably a copper-tin layer which has been heat-treated at 150 DEG C or higher so as to contain an alloy of copper and tin.

The content of copper and the content of tin in the entire copper-tin layer 3 can be adjusted by adjusting the thicknesses of the copper layer 52 and the tin layer 53 in the conductive particles 51.

The conductive particle according to the present invention is preferably a conductive particle obtained by heating a conductive particle provided with a tin layer on the surface of the copper layer provided on the surface of the base particle.

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

The conductive particles 11 shown in Fig. 2 include base particles 2 and a copper-tin layer 12 provided on the surface 2a of the base particles 2. The copper-tin layer 12 is a conductive layer. The conductive particles 11 have a plurality of core materials 13 on the surface 2a of the base particle 2. The copper-tin layer 12, which is a conductive layer, covers the core material 13. Since the conductive material covers the core material 13, the conductive particles 11 have a plurality of protrusions 14 on the surface 11a. The conductive particles 11 have a plurality of projections 14 on the outer surface 12a of the copper-tin layer 12. The projections 14 are 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 material 13 and the projections 14 are formed. And the core material 13 is disposed 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 conductive particles 11 have insulating particles 15 disposed on the surface 12a of the copper-tin layer 12. [ The insulating particles 15 are insulating materials. Another conductive layer such as a palladium layer may exist between the copper-tin layer and the insulating particles. In this embodiment, a part of the surface 12a of the copper-tin layer 12 is covered with the insulating particles 15. Thus, the conductive particles may have insulating particles 15 attached on the surface of the conductive layer such as a copper-tin layer. However, the insulating particles 15 may not necessarily be provided. In place of the insulating particles 15, an insulating resin layer may be provided. The conductive particles may have an insulating resin layer adhered on the surface of a conductive layer such as a copper-tin layer. The surface of the conductive layer such as a copper-tin layer may be covered with an insulating resin layer. The insulating resin layer is an insulating material.

Fig. 5 is a cross-sectional view of the conductive particles according to the third embodiment of the present invention.

The conductive particles 61 shown in Fig. 5 include base particles 2, a copper-tin layer 3, and a second conductive layer 62. The second conductive layer 62 is provided on the surface 3a of the copper-tin layer 3 in the conductive particle 1. The second conductive layer 62 is different from the copper-tin layer 3. A second conductive layer may be provided on the surface 12a of the copper-tin layer 12 in the conductive particles 11. [ It is also possible to provide a second conductive layer on the surface of the base particles and a copper-tin layer on the second conductive layer. That is, the second conductive layer may be disposed between the base particles and the copper-tin layer.

6 is a sectional view of the conductive particles according to the fourth embodiment of the present invention.

The conductive particles 71 shown in Fig. 6 include base particles 2 and a copper-tin layer 72 provided on the surface 2a of the base particles 2. The copper-tin layer 72 has a first region and a region that is thinner than the first region. The copper-tin layer 72 has thickness variations.

Examples of the base particles include resin particles, inorganic particles, organic-inorganic hybrid particles and metal particles.

The base particles are preferably resin particles formed by a resin. When the electrodes are connected, the conductive particles are disposed between the electrodes, and then the conductive particles are generally compressed. When the base particles are resin particles, the conductive particles are easily deformed by compression, and the contact area between the conductive particles and the electrode is increased. Therefore, the reliability of conduction between the electrodes can be improved.

As the resin for forming the resin particles, various organic materials are preferably used. Examples of the resin for forming the resin particles include polyolefins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polypropylene, polyisobutylene, and 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 ethylenic unsaturated group, it is possible to design and synthesize resin particles having a certain physical property at the time of compression suitable for a conductive material.

When the resin particles are obtained by polymerizing a monomer having an ethylenic unsaturated group, examples of the monomer having an ethylenic unsaturated group include a monomer which is incompatible with the monomer and a monomer which is crosslinkable.

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. This method includes, for example, suspension polymerization in the presence of a radical polymerization initiator, and polymerization in which unconverted seed particles are swollen with the radical polymerization initiator to swell the monomers.

When the base particles are inorganic particles or organic-inorganic hybrid particles, examples of inorganic substances for forming base particles include silica and carbon black. The particles formed by the silica are not particularly limited. For example, particles obtained by hydrolyzing a silicon compound having two or more hydrolyzable alkoxyl groups to form crosslinked polymer particles, and then firing if necessary, .

When the base particles are metal particles, examples of the metal for forming the metal particles include silver, copper, nickel, silicon, gold and titanium. However, it is preferable that the base particles are not metal particles.

The average particle size of the base particles is preferably in the range of 1 to 100 mu m. When the average particle size of the base particles is 1 占 퐉 or more, the reliability of conduction between the electrodes can be further increased. If the average particle size of the base particles is 100 m or less, the interval between the electrodes can be narrowed. A more preferable lower limit of the average particle size of the base particles is 2 mu m, a more preferable upper limit is 50 mu m, a more preferable upper limit is 30 mu m, and a particularly preferable upper limit is 5 mu m.

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

The copper-tin layer may have a spherical shape with a smooth external surface, a concavo-convex shape formed by a flaky or plate-like metal piece, and the external surface may be roughly spherical. The copper-tin layer may be a single-layer conductive layer or a conductive layer in which a plurality of scaly or plate-like conductive materials are stacked.

The Vickers hardness (Hv) of the copper-tin layer is preferably 100 or more, and preferably 500 or less. When the Vickers hardness of the copper-tin layer is not less than the lower limit and not more than the upper limit, cracking of the conductive layer is less likely to occur, and reliability of conduction in the connection structure is further increased.

The melting point of the copper-tin layer is preferably 550 占 폚 or higher, and more preferably 600 占 폚 or higher. The upper limit of the melting point of the copper-tin layer is not particularly limited. If the melting point of the copper-tin layer is not lower than the lower limit, excessive thermal deformation and leakage of the copper-tin layer can be suppressed.

The melting point of the copper-tin layer is a value measured by DSC (differential scanning calorimetry, "EXSTAR X-DSC7000" manufactured by SII).

The copper-tin layer may have a first region and a second region that is thinner than the first region. The maximum thickness of the copper-tin layer may be more than 1 times the minimum thickness, 1.1 times or more, 1.5 times or more, or 2 times or more. When the thickness variation of the copper-tin layer is large, the binder resin between the conductive particles and the electrode is effectively removed when obtaining the connection structure using the anisotropic conductive material including the conductive particles and the binder resin. As a result, the reliability of conduction in the resulting connection structure is improved. It is also easy to increase the thickness variation by forming the copper-tin layer by a physical or mechanical hybridization method described later.

The average thickness of the copper-tin layer is preferably in the range of 10 to 1000 nm. A more preferable lower limit of the average thickness of the copper-tin layer is 20 nm, a more preferable lower limit 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. When the average thickness of the copper-tin layer is not lower than the lower limit described above, the conductivity of the conductive particles can be further increased. When the average thickness of the copper-tin layer is less than the upper limit, the difference in coefficient of thermal expansion between the base particles and the copper-tin layer becomes small, and the copper-tin layer becomes difficult to peel off from the base particles.

Examples of the method of forming the copper layer on the surface of the substrate particle to form the copper-tin layer include a method of forming a copper layer by electroless plating and a method of forming a copper layer by electroplating have. Examples of a method for forming a tin layer on the surface of a copper layer in order to form a copper-tin layer include a method of forming a tin layer by electroless plating and a method of forming a tin layer by electroplating . As a preferable method of 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 the physical or mechanical hybridization method, a hybridizer or the like is used.

The copper-tin layer may contain a metal other than copper and tin to the extent that the object of the present invention is not impaired. 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, 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 wt% or less, more preferably 10 wt% or less, further preferably 5 wt% % Or less, particularly preferably 1 wt% or less.

The conductive particles may have the second 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 more preferably a palladium layer. The second conductive layer is preferably provided on the surface of the copper-tin layer.

The average thickness of the second conductive layer is preferably 5 nm or more. If the average thickness of the second conductive layer is 5 nm or more, it is easy to uniformly coat the second conductive layer. When the second conductive layer is provided on the surface of the copper-tin layer, resistance to the external environment of the conductive particles is increased, the copper-tin layer is hardly oxidized, and copper in the copper- Corrosion of copper due to the galvanic reaction between the metal (palladium or the like) constituting the second conductive layer is less likely to occur. Therefore, the conductivity of the entire conductive layer in the conductive particles can be further increased.

The average thickness of the second conductive layer is preferably 500 nm or less. If the average thickness of the second conductive layer is 500 nm or less, the cost of the conductive particles is lowered. Further, since the amount of metal constituting the second conductive layer can be reduced, the environmental load can be reduced.

A preferable lower limit of the average thickness of the palladium layer is 10 nm, and a more preferable upper limit is 400 nm. When the average thickness of the palladium layer is 10 nm or more, the conductivity of the conductive particles can be further increased.

Like the conductive particles 11, the conductive particles according to the present invention preferably have projections on the surface. The Vickers hardness (Hv) of the copper-tin layer is preferably 100 or more, and the conductive particles preferably have projections on the surface. It is preferable that the conductive particles have projections on the surface of the conductive layer, and furthermore, it is preferable that the conductive particles have projections on the surface of the copper-tin layer or the second conductive layer (palladium layer, etc.). It is preferable that the projections are plural. In many cases, an oxide film is formed on the surface of the electrode connected by the conductive particles. When conductive particles having protrusions are used, conductive particles are disposed between the electrodes and pressed, whereby the oxide film is effectively removed by protrusions. Therefore, the electrode and the conductive layer of the conductive particle can be more reliably contacted, and the connection resistance between the electrodes can be lowered. When the conductive particles are provided with an insulating material (such as an insulating resin layer or insulating particles) on the surface, or when the conductive particles are dispersed in the resin and used as an anisotropic conductive material, Can be effectively eliminated. Therefore, the reliability of conduction between the electrodes can be improved.

Examples of the method for forming protrusions on the surface of the conductive particles include a method in which a core material is attached to the surface of base particles and then a conductive layer is formed by electroless plating and a method in which a conductive layer is formed on the surface of base particles by electroless plating A method in which a core material is attached, and a conductive layer is formed by electroless plating, and the like.

As a method for attaching the core material to the surface of the base particles, for example, a conductive material to be a core material is added to a dispersion of the base particles, and a core material is accumulated on the surface of the base particles by, for example, Van der Waals force And a method in which a conductive material to be a core material is added to a container containing base particles and a core material is adhered to the surface of the base particles by mechanical action by rotation of the container or the like. Among them, a method of integrating and adhering the core material on the surface of the base particles in the dispersion is preferable because it is easy to control the amount of the core material to be adhered.

Examples of the conductive material constituting the core material include conductive metals such as metals, oxides of metals, graphite, and conductive polymers. Examples of the conductive polymer include polyacetylene. Among them, a metal is preferable because the conductivity can be increased.

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, Alloys, tin-copper alloys, tin-silver alloys, and tin-lead-silver alloys. Among them, 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 conductive particles 11, the conductive particles according to the present invention preferably include an insulating material disposed on the surface of the copper-tin layer or the palladium layer. In this case, when conductive particles are used for connection between electrodes, it is possible to prevent a short circuit between adjacent electrodes. Specifically, since a plurality of conductive particles are in contact with each other, an insulating material exists between the plurality of electrodes, so that a short circuit between electrodes adjacent to each other in the transverse direction, not between the upper and lower electrodes, can be prevented. Further, by pressing the conductive particles with two electrodes at the time of connection between the electrodes, it is possible to easily exclude the insulating material between the conductive layer of the conductive particles and the electrode. When the conductive particles have protrusions on the surface of the palladium layer, the insulating material between the conductive layer of the conductive particles and the electrode can be more easily excluded. The insulating material is preferably an insulating resin layer or insulating particles. The insulating particles are preferably insulating resin particles.

Specific examples of the insulating material include a polyolefin, a (meth) acrylate polymer, a (meth) acrylate copolymer, a block polymer, a thermoplastic resin, a crosslinked product of a thermoplastic resin, a thermosetting resin and a water-soluble resin.

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-acrylic acid ester copolymer, SB-type styrene-butadiene block copolymer and SBS-type styrene-butadiene block copolymer, and hydrogenated products thereof. Examples of the thermoplastic resin include vinyl polymers and vinyl copolymers. Examples of the thermosetting resin include an epoxy resin, a phenol resin, and a melamine resin. 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 conductive particles according to the present invention include insulating particles attached to the surface of the conductive layer. In this case, when the conductive particles are used for connection between the electrodes, it is possible not only to further prevent short-circuiting between adjacent electrodes in the transverse direction but also to further reduce the connection resistance between the connected upper and lower electrodes.

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, insulating particles are adhered to a conductive layer of metal surface particles by hetero-agglomeration by van der Waals force or electrostatic force, Method. Examples of the physical or mechanical method include spray drying, hybridization, electrostatic deposition, spraying, dipping and vacuum deposition. Among them, a method of attaching an insulating material to the surface of the conductive layer through chemical bonding is preferable because it is difficult for the insulating material to be desorbed.

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 excessively large, and electrical connection by the conductive layer is achieved more reliably. When the particle diameter of the insulating particles is 1/5 or less of the particle diameter of the conductive particles, the insulating particles can be efficiently adsorbed on the surface of the conductive particles when the insulating particles are adhered by the hetero-aggregation method. 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 size of the insulating particles is not smaller than the lower limit, the distance between the adjacent conductive particles becomes larger than the hopping distance of the electrons, and leakage is less likely to occur. When the particle diameter of the insulating particles is less than the upper limit, the pressure and the amount of heat required for thermocompression bonding become small.

The CV value of the particle diameter of the insulating particles is preferably 20% or less. When the CV value is 20% or less, the thickness of the coating layer of the conductive particles becomes uniform, pressure is uniformly applied when thermocompression bonding is performed between the electrodes, and conduction failure is less likely to occur. The CV value of the particle diameter is calculated by the following equation.

CV value of particle diameter (%) = standard deviation of particle diameter / average particle diameter x 100

The particle size distribution can be measured by a particle size distribution meter before covering the metal surface particles and can be measured by image analysis of SEM photographs after coating.

In order to expose the conductive layer of the conductive particles, the covering ratio by the insulating material is preferably 5% or more, and preferably 70% or less. The covering ratio of the insulating material is an area of a portion covered with an insulating material that occupies the entire surface area of the metal surface particles. If the covering ratio is 5% or more, the adjacent conductive particles are more reliably insulated by the insulating material. When the covering ratio is 70% or less, it is not necessary to apply heat and pressure more than necessary when the electrodes are connected, and deterioration of the performance 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.

The organic polymer particles are preferably resin particles obtained by (co) polymerizing one or more kinds of monomers having an unsaturated double bond. Examples of the monomer having an unsaturated double bond include (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. Among them, (meth) acrylate esters are preferably used.

It is preferable that the insulating particles have a polar functional group in order to adhere to the conductive layer of the conductive particles by hetero-aggregation. Examples of the polar functional group include an ammonium group, a sulfonium group, a phosphoric acid group, and a hydroxysilyl group. The polar functional group can be introduced by copolymerizing the polar functional group with a monomer having an unsaturated double bond.

Examples of the monomer having an ammonium group include N, N-dimethylaminoethyl methacrylate, N, N-dimethylaminopropylacrylamide and N, N, N-trimethyl- . Examples of the monomer having sulfonium include phenyldimethylsulfonium methacrylate, methylsulfate, and the like. Examples of the monomer having a phosphoric acid group include acid phosphoxyethyl methacrylate, acid phosphoxypropyl methacrylate, acid phosphoxypolyoxyethylene glycol monomethacrylate, and acid phosphoxypolyoxypropylene glycol monomethacrylate And the like. Examples of the monomer having a hydroxysilyl group include vinyltrihydroxysilane and 3-methacryloxypropyltrihydroxysilane.

As another method of introducing the polar functional group onto the surface of the insulating particles, there is a method of using a radical initiator having a polar group as an initiator in the polymerization of the monomer having an unsaturated double bond. 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 according to the present invention includes the above-mentioned conductive particles and a binder resin.

The binder resin is not particularly limited. As the binder resin, an insulating resin is generally used. Examples of the binder resin include a vinyl resin, a thermoplastic resin, a curable resin, a thermoplastic block copolymer and an elastomer. The binder resin may be used alone or in combination of two or more.

Examples of the vinyl resin include vinyl acetate resin, acrylic resin and styrene resin. Examples of the thermoplastic resin include a polyolefin resin, an ethylene-vinyl acetate copolymer, and a 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 styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, hydrogenation product of styrene-butadiene-styrene block copolymer, and styrene-isoprene- Hydrogenated products, and the like. Examples of the elastomer include styrene-butadiene copolymer rubber and acrylonitrile-styrene block copolymer rubber.

The anisotropic conductive material may contain, in addition to the conductive particles and the binder resin, a filler, an extender, a softener, a plasticizer, a polymerization catalyst, a curing catalyst, a colorant, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, Flame retardant, and the like.

The method of dispersing the conductive particles in the binder resin may be any conventionally known dispersion method and is not particularly limited. Examples of the 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; a method in which the conductive particles are homogeneously dispersed in water or an organic solvent A method in which the binder resin is uniformly dispersed in a binder resin and then added to the binder resin and kneaded and dispersed by a planetary mixer or the like and a method in which the binder resin is diluted with water or an organic solvent, Followed by kneading with a planetary mixer or the like and dispersing the mixture.

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

It is preferable that the anisotropic conductive material is an anisotropic conductive paste from the viewpoint of suppressing the occurrence of voids in the connection portion in the connection structure and further improving the reliability of conduction. The anisotropic conductive material is an anisotropic conductive paste and is preferably an anisotropic conductive material coated on the upper surface of the member to be connected in a paste state.

The content of the binder resin in 100 wt% of the anisotropic conductive material is preferably in the range of 10 to 99.99 wt%. A more preferable lower limit of the content of the binder resin is 30% by weight, a more preferable lower limit is 50% by weight, particularly preferably a lower limit is 70% by weight, and a more preferable upper limit is 99.9% by weight. When the content of the binder resin satisfies the lower limit and the upper limit, the conductive particles can be efficiently arranged between the electrodes, and the reliability of conduction between the electrodes can be further enhanced.

The content of the conductive particles in 100 wt% of the anisotropic conductive material is preferably in the range of 0.01 to 20 wt%. A more preferable lower limit of the content of the conductive particles is 0.1 wt%, and a more preferable upper limit is 10 wt%. When the content of the conductive particles satisfies the lower limit and the upper limit, the reliability of conduction between the electrodes can be further enhanced.

(Connection structure)

By connecting the connection target members using the conductive particles according to the present invention or an anisotropic conductive material including the conductive particles and the binder resin, a connection structure can be obtained.

Wherein the connection structure includes a first connection target member, a second connection target member, and a connection unit connecting the first and second connection target members, wherein the connection unit is formed by the conductive particles of the present invention, Or a connection structure formed by an anisotropic conductive material containing the conductive particles and a binder resin. When conductive particles are used, the connection itself is conductive particles. That is, the first and second connection target members are connected by the conductive particles.

3 is a front sectional view schematically showing a connection structure using conductive particles according to an embodiment of the present invention.

The connection structure 21 shown in Fig. 3 connects the first connection target member 22, the second connection target member 23 and the first and second connection target members 22 and 23 As shown in Fig. The connecting portion 24 is formed by curing an anisotropic conductive material containing the conductive particles 1. [ 3, the conductive particles 1 are schematically shown for convenience of illustration. Instead of the conductive particles 1, the conductive particles 11, 61, and 71 may be used.

The first connection target member 22 has a plurality of electrodes 22b on its upper surface 22a. The second connection target member 23 has a plurality of electrodes 23b on the lower surface 23a. The electrode 22b and the electrode 23b are electrically connected by one or a plurality of conductive particles 1. [ Therefore, the first and second connection target members 22 and 23 are electrically connected by the conductive particles 1. [

The manufacturing method of the connection structure is not particularly limited. As an example of a manufacturing method of the connection structure, there is a method of arranging the anisotropic conductive material between the first connection target member and the second connection target member to obtain a laminate, and then heating and pressing the laminate.

The pressure of the pressurization is about 9.8 x 10 ⁴ to 4.9 x 10 ⁶ Pa. The temperature of the heating is about 120 to 220 占 폚. The use of the conductive particles according to the present invention makes it difficult for the copper-tin layer to generate a large crack even when such a pressure is applied. Therefore, the reliability of conduction between the electrodes can be improved.

Specifically, examples of the member to be connected include electronic parts such as a semiconductor chip, a capacitor and a diode, and a circuit board such as a printed board, a flexible printed board and a glass board.

Examples of the electrode provided on the member to be connected include a metal electrode 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 target 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. When the electrode is an aluminum electrode, it may be an electrode formed only of aluminum, or an electrode in which an aluminum layer is laminated on the surface of the metal oxide layer. Examples of the metal oxide 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.

For example, conductive particles may be used as a conductive material for electrical connection between the upper and lower substrates constituting the liquid crystal display element, for example, in a separate use form of the conductive particles according to the present invention. A method in which conductive particles are mixed and dispersed in a thermosetting resin or a curable resin for a thermal UV bottle in a spot manner on one of the substrates and bonded to the counter substrate and a method in which conductive particles are mixed and dispersed in a peripheral sealing agent, And a method in which the sealing seal and the upper and lower substrates are electrically connected together. In any of these modes of use, the conductive particles according to the present invention can be applied. Further, since the conductive particles according to the present invention are provided on the surface of the base particles, the conductive connection can be made without damaging the transparent substrate or the like due to excellent elasticity of the base particles.

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples. The present invention is not limited to the following embodiments.

(Example 1)

(1) Resin particle formation process

To 800 parts by weight of an aqueous solution containing 3% by weight of polyvinyl alcohol ("GH-20" manufactured by Nippon Gosei Chemical Industry Co., Ltd.), 70 parts by weight of divinylbenzene, 30 parts by weight of trimethylolpropane trimethacrylate, 2 parts by weight were added and mixed by stirring. The mixture was heated to 80 DEG C under stirring in a nitrogen atmosphere, and the reaction was carried out for 15 hours to obtain resin particles.

The resulting resin particles were washed with distilled water and methanol, and classified to obtain resin particles having an average particle diameter of 4.1 mu m and a variation coefficient of 5.0%. Hereinafter, the resin particle A may be described.

(2) Electroless copper plating process

10 g of the obtained resin particle A was etched and then washed with water. Subsequently, palladium sulfate was added to the resin particles, and palladium ions were adsorbed on the resin particles.

Then, resin particles adsorbed with palladium ions were added to an aqueous solution containing 0.5% by weight of dimethylamine borane, and palladium was activated. 500 mL of distilled water was added to the resin particles to obtain a particle suspension.

Further, it contains 40 g / L of copper sulfate (pentahydrate), 100 g / L of ethylenediamine acetic acid (EDTA), 50 g / L of sodium gluconate and 25 g / L of formaldehyde, An electroless plating solution adjusted to 10.5 was prepared. The above electroless plating solution was gradually added to the above-mentioned particle suspension, and electroless copper plating was carried out while stirring at 50 캜. Thus, copper-plated particles having a copper layer (thickness of about 40 nm) provided on the surface thereof were 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. The plating solution was allowed to react at a bath temperature of 60 캜 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 mixture was allowed to react at a bath temperature of 60 占 폚 for 20 minutes to obtain particles having a tin layer (about 72 nm in thickness) .

(4) Alloying process

The particles having the tin layer formed on the surface of the copper layer were heated at 220 캜 for 20 hours. After heating, the copper and tin layers were alloyed. Thus, conductive particles having a copper-tin layer (thickness of about 100 nm) provided on the surface of the resin particles and the copper-tin layer containing an alloy of copper and tin were obtained. As a result of evaluating the content of copper and tin contained in the entire copper-tin layer in the obtained conductive particles, the content of copper was 40% by weight and the content of tin was 60% by weight.

(Example 2)

Except that the thickness of the copper layer was set to about 50 nm in the electroless copper plating process and that the thickness of the tin layer was changed to about 60 nm in the electroless tin plating process, A copper-tin layer (thickness: about 100 nm) was provided on the copper-tin layer, and the copper-tin layer contained the copper-tin alloy. The content of copper and tin contained in the entire copper-tin layer in the obtained conductive particles was evaluated. As a result, the content of copper was 50% by weight and the content of tin was 50% by weight.

(Example 3)

Except that the thickness of the copper layer was set to about 60 nm in the electroless copper plating process and that the thickness of the tin layer was changed to about 48 nm in the electroless tin plating process, A copper-tin layer (thickness: about 100 nm) was provided on the copper-tin layer, and the copper-tin layer contained the copper-tin alloy. The content of copper and tin contained in the entire copper-tin layer in the obtained conductive particles was evaluated. As a result, the content of copper was 60% by weight and the content of tin was 40% by weight.

(Example 4)

(1) Core material deposition process

10 g of Resin Particle A obtained in Example 1 was etched and then washed with water. Subsequently, palladium sulfate was added to the resin particles, and palladium ions were adsorbed on the resin particles.

The resin particles having palladium attached thereto were stirred in 300 mL of ion-exchanged water for 3 minutes and dispersed to obtain a dispersion. Subsequently, 1 g of metal nickel particle slurry ("2020SUS" manufactured by Mitsui Kinzoku Co., Ltd., average particle diameter 200 nm) was added to the dispersion for 3 minutes to obtain resin particles having a core material attached thereto.

(2) Production of conductive particles

An electroless copper plating process, an electroless tin plating process and an alloying process were carried out in the same manner as in Example 1 except that the resin particles having the core material attached thereto were used to form a copper-tin layer on the surface of the resin particles Thereby obtaining conductive particles in which the copper-tin layer contains an alloy of copper and tin. The obtained conductive particles had protrusions on the surface of the copper-tin layer. As a result of evaluating the content of copper and tin contained in the entire copper-tin layer in the obtained conductive particles, the content of copper was 40% by weight and the content of tin was 60% by weight. When the content of copper and tin is to be determined, nickel contained as a core material is excluded.

(Example 5)

Resin Particle A was prepared by mixing copolymer resin particles of 1,4-butanediol diacrylate and tetramethylolmethane tetraacrylate (1,4-butanediol diacrylate: tetramethylolmethane tetraacrylate = 95 wt%: 5 wt% , Hereinafter sometimes referred to as Resin Particle B), to obtain conductive particles. The obtained conductive particles had protrusions on the surface of the copper-tin layer.

(Example 6)

(1) Fabrication of insulating resin particles

A 1000 mL separable flask equipped with a four-necked separable cover, a stirring blade, a three-way cock, a cooling tube and a temperature probe was charged with 100 mmol of methyl methacrylate and 100 mmol of N, N, N-trimethyl- A monomer composition comprising 1 mmol of monooxyethylammonium chloride and 1 mmol of 2,2'-azobis (2-amidinopropane) dihydrochloride was added to ion-exchanged water to a solid content of 5% by weight, and then 200 and the polymerization was carried out at 70 캜 for 24 hours under a nitrogen atmosphere. After completion of the reaction, the resultant was lyophilized to obtain an insulating resin particle having an ammonium group on its surface and having an average particle diameter of 220 nm and a CV value of 10%.

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

10 g of the conductive particles obtained in Example 5 was dispersed in 500 mL of ion-exchanged water, 4 g of an aqueous dispersion of insulating resin particles was added, and the mixture was stirred at room temperature for 6 hours. The mixture was filtered with a 3 탆 mesh filter, washed with methanol, and dried to obtain conductive particles having insulating resin particles adhered thereto.

As a result of observation by a scanning electron microscope (SEM), only one coating layer of insulating resin particles was formed on the surface of the conductive particles. The coated area of the insulating resin particles (that is, the projected area of the particle size of the insulating resin particles) from the center of the conductive particles to the area of 2.5 탆 was calculated by image analysis. The covering ratio was 30%.

(Example 7)

Conductive particles were obtained in the same manner as in Example 1 except that the resin particles A were changed to the resin particles B.

(Example 8)

Conductive particles with insulating resin particles were obtained in the same manner as in Example 6 except that the conductive particles obtained in Example 5 were replaced with the conductive particles obtained in Example 1.

(Example 9)

Conductive particles with insulating resin particles were obtained in the same manner as in Example 6 except that the conductive particles obtained in Example 5 were replaced with the conductive particles obtained in Example 4. [

(Example 10)

Conductive particles with insulating resin particles were obtained in the same manner as in Example 6 except that the conductive particles obtained in Example 5 were replaced with the conductive particles obtained in Example 7. [

(Example 11)

The conductive particles obtained in Example 1 were prepared. Using these conductive particles, the following steps (1) and (2) were carried out.

(1) Electroless palladium plating process

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

It was also found that a solution containing 4 g / L of palladium sulfate (anhydrous), 2.4 g / L of ethylenediamine, 4.0 g / L of hydrazinium sulfate and 3.5 g / L of sodium hypophosphite, An electroless plating solution was prepared. The above electroless plating solution was gradually added while agitating the above-mentioned particle suspension at 50 占 폚 to carry out electroless palladium plating. The amount of the electroless plating solution to be added was adjusted so that the thickness of the palladium layer became 10 nm. The resulting palladium-plated resin particles were washed with distilled water and methanol, and then vacuum-dried. Thus, conductive particles having a copper layer on the surface of the resin particles and a palladium layer on the surface of the copper layer were obtained.

(2) Chlorine cleaning and removal process

1 g of the obtained conductive particles was dispersed in 1000 mL of distilled water (specific resistance: 18 M?), And the mixture was stirred in an autoclave equipped with a stirrer at 121 占 폚 for 10 hours under pressure of 0.1 MPa. Thereafter, the resultant was separated by filtration and dried.

Thus, a copper-tin layer (thickness of about 100 nm) was provided on the surface of the resin particle, and the copper-tin layer contained an alloy of copper and tin, and a palladium layer Thickness: 10 nm).

(Example 12)

The resin particle A obtained in Example 1 was prepared. Copper powder (particle diameter: 3.0 to 7.0 mu m) and tin powder (particle diameter: 3.0 to 7.0 mu m) were prepared.

A copper-tin layer (thickness: 100 nm) was formed on the surface of the resin particles by physical / mechanical hybridization using a resin particle A, a copper powder and a tin powder using a hybridizer (manufactured by Nara Kai Seisakusho Co., ) Was obtained.

Then, the particles having the copper-tin layer on the surface of the obtained resin particles were heated at 220 DEG C for 20 hours. After heating, the copper and tin layers were alloyed. Thus, conductive particles were obtained in which a copper-tin layer (thickness: 100 nm) was provided on the surface of the resin particles and the copper-tin layer contained an alloy of copper and tin. The content of copper and tin contained in the whole copper-tin layer in the obtained conductive particles was evaluated. As a result, the copper content was 40 wt% and the tin content was 60 wt%. The maximum thickness in the copper-tin layer was at least twice the minimum thickness.

(Example 13)

The resin particle A used in Example 1 was prepared. Further, a copper tin alloy powder (copper content 40 wt%, tin content 60 wt%, particle diameter 3.0 to 7.0 mu m) was prepared.

A copper-tin layer (thickness: 100 nm) was formed on the surface of the resin particles by a physical / mechanical hybridization method using a resin particle A and a copper tin alloy powder using a hybridizer (manufactured by Nara Kai Seisakusho Co., Ltd.) Was obtained.

The content of copper and tin contained in the entire copper-tin layer in the obtained conductive particles was evaluated. As a result, the copper content was 40 wt% and the tin content was 60 wt%. The maximum thickness in the copper-tin layer was at least twice the minimum thickness.

(Comparative Example 1)

The resin particle A obtained in Example 1 was prepared. 10 g of the resin particle A was etched and then washed with water. Subsequently, palladium sulfate was added to the resin particles, and palladium ions were adsorbed on the resin particles.

Subsequently, resin particles adsorbed with palladium ions were added to an aqueous solution containing 0.5% by weight of dimethylamine borane to activate palladium. 500 mL of distilled water was added to the resin particles to obtain a particle suspension.

Further, it contains 40 g / L of copper sulfate (pentahydrate), 100 g / L of ethylenediamine acetic acid (EDTA), 50 g / L of sodium gluconate and 25 g / L of formaldehyde, An electroless plating solution adjusted to 10.5 was prepared. The above electroless plating solution was gradually added to the above-mentioned particle suspension, and electroless copper plating was carried out while stirring at 50 캜. Thus, copper-plated particles (conductive particles) having a copper layer (thickness: 100 nm) provided on the surface thereof were obtained. In Comparative Example 1, no tin layer was provided on the surface of the copper layer.

(Comparative Example 2)

The tin layer (thickness: about 72 nm) obtained after the electroless tin plating process of Example 1 was made conductive particles on the surface of the copper layer (thickness: about 40 nm). In Comparative Example 2, no alloying process was performed.

(Comparative Example 3)

Except that the thickness of the copper layer was set to about 80 nm in the electroless copper plating process and that the thickness of the tin layer was changed to about 20 nm in the electroless tin plating process, A copper-tin layer (thickness: 100 nm) was provided on the copper-tin layer and the copper-tin layer contained an alloy of copper and tin. The content of copper and tin contained in the entire copper-tin layer in the obtained conductive particles was evaluated. As a result, the copper content was 80% by weight and the tin content was 20% by weight.

(Comparative Example 4)

Except that the thickness of the copper layer was set to about 14 nm in the electroless copper plating process and that the thickness of the tin layer was changed to about 96 nm in the electroless tin plating process, A copper-tin layer (thickness: about 100 nm) was provided on the copper-tin layer, and the copper-tin layer contained the copper-tin alloy. The content of copper and tin contained in the entire copper-tin layer in the obtained conductive particles was evaluated. As a result, the content of copper was 15% by weight and the content of tin was 85% by weight.

(Example 14)

Except that the thickness of the copper layer in the electroless copper plating process was set to about 30 nm and that in the electroless tin plating process the thickness of the tin layer was changed to about 84 nm, A copper-tin layer (thickness: about 100 nm) was provided on the copper-tin layer, and the copper-tin layer contained the copper-tin alloy. The content of copper and tin contained in the entire copper-tin layer in the obtained conductive particles was evaluated. As a result, the content of copper was 30% by weight and the content of tin was 70% by weight.

(evaluation)

(1) cracks in the conductive layer

Two substrates each having a copper electrode with L / S of 100 mu m / 100 mu m were prepared. Further, an anisotropic conductive paste containing 10 parts by weight of the conductive particles, 85 parts by weight of an epoxy resin as a binder resin ("Stick Bond XN-5A" manufactured by Mitsui Chemicals, Inc.) and 5 parts by weight of an imidazole type curing agent was prepared .

After the anisotropic conductive paste was applied on the upper surface of the substrate so that the conductive particles came into contact with the copper electrode, the other substrate was laminated so that the copper electrode was in contact with the conductive particles, and a pressure of 3 MPa was applied thereto to obtain a laminate. Thereafter, the laminate was heated at 180 占 폚 for 1 minute to cure the anisotropic conductive paste to obtain a connection structure.

The conductive layer of the conductive particles in the resulting connection structure was evaluated for cracks. The cracks in the conductive layer were determined based on the following criteria.

[Criteria for judging cracks in the conductive layer]

?: No large cracks in the conductive layer, resin particles are not exposed

DELTA: There is a large crack in the conductive layer, and resin particles are slightly exposed.

X: There is a large crack in the conductive layer, and resin particles are exposed to a large extent

(2) Reliability of conduction

The connection resistance between the opposing electrodes of the 100 connecting structures obtained in the evaluation of the above (1) was measured by the division method, and it was evaluated whether or not the electrodes were conductive, and the reliability of conduction was judged as the following criterion.

[Criteria for reliability of conduction]

○: 100 connection structures are all conductive

[Delta]: One or two unconnected numbers among 100 connection structures

X: 3 or more nonconductive numbers among 100 connection structures

(3) Vickers hardness

The Vickers hardness of the copper-tin layer in the obtained conductive particles was measured using a Vickers hardness meter ("DUH-W201" manufactured by Shimadzu Corporation). The Vickers hardness was determined on the basis of the following.

[Vickers hardness criteria]

A: Vickers hardness exceeds 500

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

C: Vickers hardness less than 100

(4) Melting point

0.2 to 0.5 mg of conductive particles were added to an aluminum pan and the mixture was injected under the conditions of a temperature elevation rate of 10 ° C / min using DSC2920 manufactured by T.A. Instrument to obtain a heat-flow curve. In this curve, the temperature value indicated by the peak of the peak seen as melting was defined as the melting point.

(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, 5 mL of 70% nitric acid) were mixed and allowed to stand for 15 minutes in a hot water bath at 70 ° C. After the flask was taken out from the water bath, the liquid was naturally cooled so that the liquid temperature in the flask became 40 DEG C or lower. After cooling, the acidic solution containing metal ions and resin particles was filtered using a glass funnel and filter paper (Advantech manufactured filter paper, No. 5C). Liquid separation was carried out, 100 mL of an acidic solution containing metal ions was taken out, 1 mL was sampled by a micropipette, and diluted 100 times with pure water to obtain a diluted solution. The diluted solution thus obtained was measured with ICP ("ULTIMA2" manufactured by Horiba Seisakusho Co., Ltd.) and the weight of the metal of the conductive layer and the amount of each metal were calculated from the obtained metal ion concentration.

The results are shown in Table 1 below. In the following Table 1, " - " indicates that it is not evaluated.

One… Conductive particle
2… Base particles
2a ... surface
3 ... Copper-tin layer
3a ... surface
11 ... Conductive particle
11a ... surface
12 ... Copper-tin layer
12a ... surface
13 ... Core material
14 ... spin
15 ... Insulating particle
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 particle
52 ... Copper layer
52a ... surface
53 ... Tin layer
61 ... Conductive particle
62 ... The second conductive layer
71 ... Conductive particle
72 ... Copper-tin layer

Claims (8)

And a copper-tin layer containing copper and tin provided on the surface of the base particle,
Wherein the copper-tin layer comprises an alloy of copper and tin,
Wherein the copper content in the entire copper-tin layer is more than 20 wt% and not more than 75 wt%, and the tin content is less than 25 wt% and less than 80 wt%. The conductive particle according to claim 1, wherein the copper-tin layer has a melting point of 550 캜 or higher. The conductive particle according to claim 1 or 2, wherein the content of copper in the entire copper-tin layer is 40 wt% or more and 60 wt% or less, and the content of tin is 40 wt% or more and 60 wt% or less. 3. The conductive particle according to claim 1 or 2, having protrusions on the surface. 3. The conductive particle according to claim 1 or 2, comprising an insulating material disposed on a surface of the copper-tin layer. The conductive particle according to claim 5, wherein the insulating material is insulating particles. An anisotropic conductive material comprising the conductive particles according to claim 1 or 2 and a binder resin. A first connecting object member, a second connecting object member, and a connecting portion connecting the first and second connecting object members,
Wherein the connection part is formed by the conductive particles according to claim 1 or 2, or is formed by an anisotropic conductive material including the conductive particles and the binder resin.

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