JP2019075380A - Conductive particle, conductive material and connection structure - Google Patents

Abstract

To provide a conductive particle that can reduce connection resistance when electrodes are electrically connected together, and can improve the connection reliability between electrodes in a high temperature-high humidity environment.SOLUTION: A conductive particle 1 has a base particle 2, a nickel layer 3 that is disposed on the surface of the base particle 2 and contains nickel and phosphorus, and a gold layer 4 that is disposed on the external surface of the nickel layer 3 and contains gold. In 100 wt.% of the whole nickel layer 3, the content of phosphorus is less than 5 wt.%, and the thickness of the gold layer 4 is less than 15 nm, and the external surface of the gold layer 4 is subjected to rustproofing.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a conductive particle having substrate particles and a conductive layer disposed on the surface of the substrate particles. The present invention also relates to a conductive material and a connecting structure using the above-described conductive particles.

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

  The anisotropic conductive material is, for example, a connection between a flexible printed substrate and a glass substrate (FOG (Film on Glass)) and a connection between a semiconductor chip and a flexible printed substrate (COF (COF) to obtain various connection structures. It is used for chip on film), connection between semiconductor chip and glass substrate (COG (chip on glass)), connection between flexible printed circuit board and glass epoxy substrate (FOB (film on board)), and the like.

  As an example of the conductive particle, Patent Document 1 below discloses a conductive particle comprising a nickel layer and a gold layer formed on the nickel layer and having an average film thickness of 300 Å or less. ing. In this conductive particle, the gold layer is the outermost layer. Further, in this conductive particle, the elemental composition ratio (Ni / Au) of nickel and gold on the surface of the conductive particle by X-ray photoelectron spectroscopy analysis is 0.4 or less. In the embodiment of Patent Document 1, a nickel layer containing nickel and phosphorus is formed, and a gold layer having a thickness of 15 nm or more and 28 nm or less is formed.

  Examples of Patent Document 2 below disclose conductive particles in which a nickel plating layer is formed on the surface of crosslinked polystyrene particles, and a gold plating layer is formed on the outer surface of the nickel plating layer. There is. In the embodiment of Patent Document 2, a nickel layer containing nickel and phosphorus is formed, and a gold layer having a thickness of 20 nm is formed.

  Patent Document 3 below discloses conductive particles provided with core particles, a Ni plating layer, a noble metal plating layer, and a rustproof film. The Ni plating layer covers the core particles and contains Ni. The noble metal plated layer covers at least a part of the Ni plated layer, and contains at least one of Au and Pd. The anticorrosion film covers at least one of the Ni plating layer and the noble metal plating layer, and includes an organic compound.

JP, 2009-102731, A JP, 2009-280790, A JP, 2013-20721, A

  When the connection structure is obtained by electrically connecting the electrodes using conventional conductive particles as described in Patent Documents 1 to 3, the connection resistance may be increased. Furthermore, there is a problem that when the conductive particles exposed to high temperature and high humidity are used or the connection structure using the conductive particles is exposed to high temperature and high humidity, the connection resistance tends to be high.

  An object of the present invention is to provide a conductive particle capable of reducing connection resistance when electrically connecting electrodes, and enhancing connection reliability between electrodes under high temperature and high humidity. It is. Another object of the present invention is to provide a conductive material and a connection structure using the above-mentioned conductive particles.

  According to a broad aspect of the present invention, a substrate particle, a nickel layer disposed on the surface of the substrate particle and containing nickel and phosphorus, and an outer surface of the nickel layer are provided. And a gold layer containing gold, the content of phosphorus being less than 5% by weight in 100% by weight of the entire nickel layer, the thickness of the gold layer being less than 15 nm, and the outer surface of the gold layer being Provided are conductive particles that are treated to be rustproofed.

  In a specific aspect of the conductive particle according to the present invention, the thickness of the gold layer is 10 nm or less.

  In a specific aspect of the conductive particles according to the present invention, the outer surface of the gold layer is subjected to an anticorrosion treatment with a compound having a C 6-22 alkyl group.

  In a specific aspect of the conductive particles according to the present invention, in the thickness direction of the nickel layer, phosphorus is unevenly distributed so that more phosphorus is present on the gold layer side than the base particle side.

  In a specific aspect of the conductive particles according to the present invention, the outer surface of the gold layer is subjected to an anticorrosion treatment with a phosphorus-free compound.

  In one specific aspect of the conductive particle according to the present invention, the conductive particle has a plurality of protrusions on the outer surface of the gold layer.

  In one particular aspect of the conductive particle according to the present invention, the conductive particle comprises a plurality of core materials that raise the outer surface of the gold layer to form a plurality of the protrusions.

  In a specific aspect of the conductive particles according to the present invention, the material of the core material has a Mohs hardness of 5 or more.

  In a specific aspect of the conductive particle according to the present invention, the surface area of the portion with the projections is 30% or more in 100% of the total surface area of the outer surface of the gold layer.

  In one particular aspect of the conductive particle according to the present invention, the conductive particle comprises an insulating material disposed on the outer surface of the gold layer.

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

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

  The conductive particles according to the present invention are disposed on a substrate particle, a nickel layer containing nickel and phosphorus, disposed on the surface of the substrate particle, and an outer surface of the nickel layer, And a gold layer containing gold, and further, the content of phosphorus is less than 5% by weight in 100% by weight of the entire nickel layer, the thickness of the gold layer is less than 15 nm, and the gold layer is The anti-corrosion treatment of the outer surface of the electrode makes it possible to lower the connection resistance when the electrodes are electrically connected using the conductive particles according to the present invention, and the electrode under high temperature and high humidity Connection reliability can be improved.

FIG. 1 is a cross-sectional view showing a conductive particle according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a conductive particle according to a second embodiment of the present invention. FIG. 3: is sectional drawing which shows typically the bonded structure using the electroconductive particle which concerns on the 1st Embodiment of this invention.

  Hereinafter, the present invention will be described in detail.

(Conductive particles)
The conductive particle according to the present invention comprises a substrate particle, a nickel layer disposed on the surface of the substrate particle, and a gold layer disposed on the outer surface of the nickel layer. The nickel layer contains nickel and phosphorus. The gold layer contains gold.

  In the conductive particles according to the present invention, the content of phosphorus is less than 5% by weight in 100% by weight of the whole of the nickel layer. Furthermore, in the conductive particle according to the present invention, the thickness of the gold layer is less than 15 nm. Furthermore, in the conductive particle according to the present invention, the outer surface of the gold layer is subjected to anticorrosion treatment.

  By employing the above-described configuration in the conductive particle according to the present invention, the connection resistance can be lowered when the electrodes are electrically connected using the conductive particle according to the present invention. Furthermore, the connection reliability under high temperature and high humidity can be improved. Furthermore, variations in connection resistance can be reduced, and connection reliability can be improved.

  When the thickness of the gold layer is 15 nm or more, the thickness of the gold layer is less than 15 nm even though the connection resistance between the electrodes and the connection reliability between the electrodes under high temperature and high humidity do not matter much The connection resistance between the electrodes and the connection reliability between the electrodes under high temperature and high humidity can be significant problems. In the present invention, even if the thickness of the gold layer is less than 15 nm, the content of phosphorus is less than 5% by weight in 100% by weight of the entire nickel layer, and the outer surface of the gold layer is antirust treated As a result, the connection resistance between the electrodes can be lowered, and the connection reliability between the electrodes under high temperature and high humidity can be further enhanced.

  In the present invention, when the connection structure is manufactured using the conductive particles stored for a long time under high temperature and high humidity or the like, an increase in connection resistance can be suppressed. In addition, even when the connection structure is stored for a long time under high temperature and high humidity, the increase in connection resistance can be suppressed. In particular, in the conductive particle according to the present invention, since the outer surface of the gold layer is treated to prevent corrosion, connection is made despite the thin thickness of the gold layer and the presence of the nickel layer inside the gold layer. It is possible to suppress the rise in resistance. Further, since the thickness of the gold layer is considerably thin, in the conductive particles, the nickel layer may be partially exposed and the nickel layer is easily partially exposed due to the presence of a pinhole or the like. Even if the nickel layer is partially exposed, the outer surface of the gold layer is subjected to rustproofing, so that the increase in connection resistance can be suppressed.

  The conductive particles may, for example, disposing the nickel layer on the surface of the base particle, disposing the gold layer on the outer surface of the nickel layer, and preventing the outer surface of the gold layer. It can be obtained through the process of rusting.

  Hereinafter, the present invention will be clarified by describing specific embodiments and examples of the present invention with reference to the drawings. In the drawings referred to, the size, thickness and the like are appropriately changed from the actual size and thickness for convenience of illustration.

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

  As shown in FIG. 1, the conductive particle 1 includes base particles 2, a nickel layer 3 and a gold layer 4. The nickel layer 3 contains nickel and phosphorus. Gold layer 4 contains gold. The content of phosphorus is less than 5% by weight in 100% by weight of the whole of the nickel layer 3. The thickness of the gold layer 4 is less than 15 nm. The nickel layer 3 and the gold layer 4 are conductive layers. The gold layer 4 is the outermost layer in the conductive layer. In the conductive particle 1, a multilayer conductive layer is formed.

  The nickel layer 3 is disposed on the surface of the base particle 2. A nickel layer 3 is disposed between the base particle 2 and the gold layer 4. Gold layer 4 is disposed on the outer surface of nickel layer 3. The conductive particle 1 is a coated particle in which the surface of the substrate particle 2 is coated with a nickel layer 3 and a gold layer 4.

  Although not shown, the outer surface of the gold layer 4 is treated to prevent corrosion. Therefore, the conductive particle 1 is provided with an anticorrosive film on the outer surface of the gold layer 4.

  The conductive particles 1 do not have a core substance. The conductive particles 1 have no protrusions on the conductive surface. The conductive particles 1 are spherical. The nickel layer 3 and the gold layer 4 have no protrusions on the outer surface. Thus, the conductive particle according to the present invention may have no protrusion on the conductive surface, and may have a spherical shape. In addition, the conductive particles 1 do not have an insulating substance. However, the conductive particles 1 may have an insulating material disposed on the outer surface of the gold layer 4.

  The nickel layer 3 is directly laminated on the surface of the base particle 2 in the conductive particle 1. Another conductive layer may be disposed between the substrate particles 2 and the nickel layer 3. The nickel layer 3 may be disposed on the surface of the base particle 2 via another conductive layer.

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

  The conductive particles 21 shown in FIG. 2 include base particles 2, a nickel layer 22, a gold layer 23, a core material 24, and an insulating material 25. The nickel layer 22 contains nickel and phosphorus. The gold layer 23 contains gold. The content of phosphorus is less than 5% by weight in 100% by weight of the entire nickel layer 22. The thickness of the gold layer 23 is less than 15 nm. The nickel layer 22 is disposed on the surface of the base particle 2. Gold layer 23 is disposed on the outer surface of nickel layer 22.

  Although not shown, the outer surface of the gold layer 23 is subjected to antirust treatment. Therefore, the conductive particles 21 are provided with an anticorrosive film on the outer surface of the gold layer 23.

  The conductive particles 21 have protrusions 21 a on the conductive surface. The protrusions 21a are plural. The nickel layer 22 and the gold layer 23 have a plurality of protrusions 22a and 23a on the outer surface. A plurality of core substances 24 are disposed on the surface of the base particle 2. A plurality of core materials 24 are embedded in the nickel layer 22 and the gold layer 23. The core material 24 is disposed inside the protrusions 21a, 22a, 23a. The nickel layer 22 and the gold layer 23 cover a plurality of core materials 24. The outer surfaces of the nickel layer 22 and the gold layer 23 are raised by the plurality of core materials 24 to form protrusions 21a, 22a, 23a. Thus, the conductive particles according to the present invention may have protrusions on the conductive surface. The conductive particle according to the present invention may have a protrusion on the outer surface of the conductive layer. The conductive particles according to the present invention may have no protrusions on the outer surface of the nickel layer and may have protrusions on the outer surface of the gold layer. The conductive particles according to the present invention may be provided with a plurality of core substances that raise the surface of the gold layer so as to form a plurality of projections inside or inside the gold layer. The core material may be located inside the nickel layer or outside the nickel layer.

  The conductive particles 21 have an insulating material 25 disposed on the outer surface of the gold layer 23. At least a partial area of the outer surface of the gold layer 23 is covered with an insulating material 25. The insulating material 25 is formed of an insulating material and is insulating particles. Thus, the conductive particles according to the present invention may have an insulating material disposed on the outer surface of the gold layer.

  Hereinafter, details of the base particle and the conductive layer will be described.

[Base particle]
Examples of the substrate particles include resin particles, inorganic particles other than metal particles, organic-inorganic hybrid particles, metal particles and the like. The substrate particles are preferably substrate particles excluding metal particles, and more preferably resin particles, inorganic particles excluding metal particles, or organic-inorganic hybrid particles. The substrate particles may be core-shell particles.

  The base material particles are more preferably resin particles or organic-inorganic hybrid particles, and may be resin particles or organic-inorganic hybrid particles. The use of these preferred substrate particles results in more suitable conductive particles due to the electrical connection between the electrodes.

  When connecting between electrodes using the said electroconductive particle, after arrange | positioning the said electroconductive particle between electrodes, the said electroconductive particle is compressed by pressure-bonding. When the substrate particles are resin particles or organic-inorganic hybrid particles, the conductive particles are easily deformed during the pressure bonding, and the contact area between the conductive particles and the electrode becomes large. Therefore, the connection resistance between the electrodes is further lowered.

  Various organic substances are suitably used as the resin for forming the above-mentioned resin particles. Examples of the resin for forming the resin particles include polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene and polybutadiene; acrylic resins such as polymethyl methacrylate and polymethyl acrylate; Alkylene terephthalate, polycarbonate, polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, phenol resin, melamine resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polysulfone, polyphenylene Oxide, polyacetal, polyimide, polyamide imide, polyether ether Tons, polyethersulfone, and polymers such as obtained by a variety of polymerizable monomer having an ethylenically unsaturated group is polymerized with one or more thereof. A resin for forming the above-mentioned resin particles can be designed because resin particles having arbitrary compression physical properties suitable for the conductive material can be designed and synthesized, and the hardness of the substrate particles can be easily controlled to a suitable range. The polymer is preferably a polymer obtained by polymerizing one or two or more polymerizable monomers having a plurality of ethylenic unsaturated groups.

  When the resin particles are obtained by polymerizing a monomer having an ethylenically unsaturated group, as the monomer having an ethylenically unsaturated group, a monomer having a crosslinking property with a non-crosslinkable monomer is used. And a mer.

  Examples of the non-crosslinkable monomers include styrene-based monomers such as styrene and α-methylstyrene; carboxyl-containing monomers such as (meth) acrylic acid, maleic acid and maleic anhydride; methyl ( Meta) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl ( Alkyl (meth) acrylates such as meta) acrylate and isobornyl (meth) acrylate; oxygen such as 2-hydroxyethyl (meth) acrylate, glycerol (meth) acrylate, polyoxyethylene (meth) acrylate and glycidyl (meth) acrylate (Meth) acrylates; nitrile-containing monomers such as (meth) acrylonitrile; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether and propyl vinyl ether; vinyl acids such as vinyl acetate, vinyl butyrate, vinyl laurate and vinyl stearate Esters; unsaturated hydrocarbons such as ethylene, propylene, isoprene and butadiene; trifluoromethyl (meth) acrylates, pentafluoroethyl (meth) acrylates, halogen-containing monomers such as vinyl chloride, vinyl fluoride and chlorostyrene, etc. Can be mentioned.

  Examples of the crosslinkable monomer include, for example, tetramethylolmethane tetra (meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolmethane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and dipentamer. Erythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, glycerol tri (meth) acrylate, glycerol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) Multifunctional (meth) acrylates such as acrylate, (poly) tetramethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate; triallyl (iso) cyanurets And silane-containing monomers such as triallyl trimellitate, divinylbenzene, diallyl phthalate, diallyl acrylamide, diallyl ether, .gamma .- (meth) acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, vinyltrimethoxysilane, etc. Be

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

  When the substrate particles are inorganic particles or organic-inorganic hybrid particles other than metal particles, examples of the inorganic substance for forming the substrate particles include silica, alumina, barium titanate, zirconia, carbon black and the like. . It is preferable that the said inorganic substance is not a metal. The particles formed of the above silica are not particularly limited. For example, after forming a crosslinked polymer particle by hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups, baking is carried out as necessary. The particles obtained by carrying out are mentioned. As said organic-inorganic hybrid particle | grains, the organic-inorganic hybrid particle | grains etc. which were formed, for example by bridge | crosslinking alkoxy silyl polymer and acrylic resin are mentioned.

  The organic-inorganic hybrid particle is preferably a core-shell type organic-inorganic hybrid particle having a core and a shell disposed on the surface of the core. It is preferable that the said core is an organic core. It is preferable that the said shell is an inorganic shell. From the viewpoint of effectively reducing the connection resistance between the electrodes, the base particle is preferably an organic-inorganic hybrid particle having an organic core and an inorganic shell disposed on the surface of the organic core.

  As a material for forming the said organic core, resin etc. for forming the resin particle mentioned above are mentioned.

  As a material for forming the said inorganic shell, the inorganic substance for forming the base material particle mentioned above is mentioned. The material for forming the inorganic shell is preferably silica. The inorganic shell is preferably formed on the surface of the core by forming a metal alkoxide into a shell by a sol-gel method and then firing the shell. The metal alkoxide is preferably a silane alkoxide. The inorganic shell is preferably formed of a silane alkoxide.

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

  The particle diameter of the substrate particles is preferably 0.1 μm or more, more preferably 0.5 μm or more, still more preferably 2 μm or more, preferably 5 μm or less, more preferably 3 μm or less. When the particle diameter of the base particle is not less than the lower limit and not more than the upper limit, the distance between the electrodes is small, and small conductive particles can be obtained even if the thickness of the conductive layer is increased.

  The particle diameter of the substrate particle indicates a diameter when the substrate particle is spherical, and indicates a maximum diameter when the substrate particle is not spherical.

[Conductive layer]
The conductive particles have the nickel layer as the conductive layer. The above-mentioned nickel layer includes not only the case where only nickel is used as a metal, but also the case where nickel and other metals are used. The nickel layer may be a nickel alloy layer.

  As metals other than nickel in the above nickel layer, silver, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, palladium, chromium, titanium, antimony, bismuth, thallium, germanium, cadmium, silicon, tungsten And molybdenum and tin-doped indium oxide (ITO). One of these metals may be used alone, or two or more of these metals may be used in combination. The nickel layer preferably contains tungsten because the conductive layer and the projections are effectively hardened. When the conductive layer and the projections become hard, the oxide film tends to be effectively eliminated.

  The nickel layer preferably contains nickel as a main metal. It is preferable that content of nickel is 50 weight% or more in 100 weight% of the said whole nickel layers. The content of nickel is preferably 65% by weight or more, more preferably 80% by weight or more, and still more preferably 90% by weight or more based on 100% by weight of the entire nickel layer. The connection resistance between electrodes becomes still lower that content of nickel is more than the above-mentioned lower limit.

  In order to reduce the connection resistance between the electrodes and to improve the connection reliability between the electrodes under high temperature and high humidity, the nickel layer contains phosphorus, and the content of phosphorus is 5 in 100% by weight of the whole nickel layer. It is less than weight percent. From the viewpoint of effectively expressing both the low connection resistance between the electrodes and the high connection reliability between the electrodes under high temperature and high humidity, the phosphorus content is 0 weight in 100 weight% of the entire nickel layer. %, More preferably 0.1% by weight or more, still more preferably 2% by weight or more. When the content of phosphorus is equal to or more than the above lower limit, the connection resistance is further lowered. From the viewpoint of further lowering the connection resistance, the content of phosphorus is preferably 4.9% by weight or less, more preferably 4% by weight or less, and still more preferably 3% by weight or less in 100% by weight of the entire nickel layer. is there.

  The phosphorus content has a gradient so that the phosphorus content on the gold layer side (outside) is larger than the phosphorus content on the base particle side (inner side) in the thickness direction of the nickel layer preferable. In the thickness direction of the nickel layer, it is preferable that phosphorus be unevenly distributed so that more phosphorus is present on the gold layer side than on the base particle side. The presence of such concentration gradients makes the connection resistance more reliable.

  In the thickness direction of the nickel layer, phosphorus is unevenly distributed so that the region of the thickness 1/2 on the gold layer side is more than the region of the thickness 1/2 on the base particle side preferable.

  The absolute value of the difference between the phosphorus content in the entire thickness 1/2 area on the base particle side and the phosphorus content in the entire thickness 1/2 area on the gold layer is preferably 2% by weight The content is more preferably 5% by weight or more, still more preferably 10% by weight or more, and preferably 19% by weight or less. The reliability of connection resistance becomes still higher that the absolute value of the difference of content of phosphorus is more than the said minimum and below the said upper limit.

  The thickness of the nickel layer is preferably 30 nm or more, more preferably 60 nm or more, preferably 200 nm or less, and more preferably 100 nm or less. The oxide film of the surface of an electrode is removed much more effectively as the thickness of the above-mentioned nickel layer is more than the above-mentioned lower limit and below the above-mentioned upper limit, and the connection resistance between electrodes becomes still lower. The thickness of the nickel layer indicates the average thickness of the nickel layer in the conductive particles.

  The conductive particles have the gold layer as the conductive layer. The above-mentioned gold layer includes not only the case of using only gold but also the case of using gold and other metals as the metal. The gold layer may be a gold alloy layer. The conductive particles preferably have a gold layer as the outermost layer of the conductive layer. It is preferable that a gold layer be disposed on the outermost surface of the conductive layer.

  Examples of metals other than gold in the gold layer include silver, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, palladium, chromium, titanium, antimony, bismuth, thallium, germanium, cadmium Silicon, tungsten, molybdenum and tin-doped indium oxide (ITO). One of these metals may be used alone, or two or more of these metals may be used in combination.

  The gold layer preferably contains gold as a main metal. The content of gold is preferably 50% by weight or more in 100% by weight of the entire gold layer. The content of gold is preferably 90% by weight or more, more preferably 95% by weight or more, and still more preferably 99.9% by weight or more, based on 100% by weight of the entire gold layer. When the content of gold is equal to or more than the above lower limit, the electrode and the conductive particle are more appropriately contacted, and the connection resistance between the electrodes is further reduced.

  The thickness of the gold layer is less than 15 nm, more preferably 10 nm or less, further preferably less than 10 nm, preferably 3 nm or more, more preferably 5 nm or more. When the thickness of the gold layer is not less than the lower limit and not more than the upper limit, an increase in connection resistance can be effectively suppressed. In the conductive particle according to the present invention, even if the thickness of the gold layer is thin, the connection resistance between the electrodes can be reduced because the gold layer is dense, and the variation in connection resistance between the electrodes can be suppressed. be able to. Further, even if the thickness of the gold layer is less than 10 nm and the thickness of the gold layer is considerably thin, the thickness of the gold layer is thin and the thickness of the gold layer is thin when the outer surface of the gold layer is subjected to rustproofing treatment. Despite the presence of the nickel layer inside the gold layer, the increase in connection resistance can be suppressed. In addition, the gold layer may not be a continuous film, and in this case, the thickness of the gold layer is less than 15 nm, and the outer surface of the gold layer is subjected to rustproofing treatment. Despite the thinness and the presence of the nickel layer inside the gold layer, the increase in connection resistance can be suppressed.

  The method for forming the conductive layer is not particularly limited. As the method of forming the conductive layer, for example, a method by electroless plating, a method by electroplating, a method by physical vapor deposition, and a method of coating metal powder or a paste containing metal powder and a binder on the surface of particles Can be mentioned. Among them, the method by electroless plating is preferable because the formation of the conductive layer is simple. Examples of the method by physical vapor deposition include methods such as vacuum deposition, ion plating and ion sputtering.

  As a method of controlling the content of nickel and phosphorus in the conductive layer, for example, a method of controlling the pH of a nickel plating solution when forming the conductive layer by electroless nickel plating, a conductive layer by electroless nickel plating In forming the above, a method of adjusting the concentration of the phosphorus-containing reducing agent, a method of adjusting the concentration of nickel in the nickel plating solution, and the like can be mentioned.

  In the method of forming by electroless plating, a catalyzing step and an electroless plating step are generally performed. Hereinafter, an example of a method of forming an alloy plating layer containing nickel and phosphorus on the surface of a resin particle by electroless plating will be described.

  In the catalyzing step, a catalyst serving as a starting point for forming a plating layer by electroless plating is formed on the surface of the resin particle.

  As a method of forming the catalyst on the surface of the resin particle, for example, after adding the resin particle to a solution containing palladium chloride and tin chloride, the surface of the resin particle is activated with an acid solution or an alkaline solution, A method of depositing palladium on the surface of a resin particle, and after adding the resin particle to a solution containing palladium sulfate and aminopyridine, the surface of the resin particle is activated with a solution containing a reducing agent to obtain resin particles The method etc. which precipitate palladium on the surface are mentioned. A phosphorus-containing reducing agent is suitably used as the reducing agent.

  In the electroless plating step, a nickel plating bath containing a nickel-containing compound and the phosphorus-containing reducing agent is preferably used. By immersing the resin particles in a nickel plating bath, nickel can be deposited on the surface of the resin particles having the catalyst formed on the surface, and a conductive layer containing nickel and phosphorus can be formed.

  Examples of the nickel-containing compound include nickel sulfate and nickel chloride. The nickel-containing compound is preferably a nickel salt. Examples of the phosphorus-containing reducing agent include sodium hypophosphite and the like.

  The particle diameter of the conductive particles is preferably 0.5 μm or more, more preferably 1 μm or more, preferably 100 μm or less, more preferably 20 μm or less, and still more preferably 5 μm or less. When the particle diameter of the conductive particle is not less than the lower limit and not more than the upper limit, the contact area between the conductive particle and the electrode becomes sufficiently large when the conductive particles are used to connect the electrodes, and It becomes difficult to form aggregated conductive particles when forming a layer. In addition, the distance between the electrodes connected via the conductive particles does not become too large, and the conductive layer becomes difficult to peel off from the surface of the substrate particles. The particle diameter of the conductive particles is also preferably 3 μm or less.

  The particle diameter of the conductive particles indicates a diameter when the conductive particles are spherical, and indicates a maximum diameter when the conductive particles are not spherical.

  The conductive particle according to the present invention preferably has a protrusion on the conductive surface. The nickel layer preferably has a protrusion on the outer surface. The gold layer preferably has a protrusion on the outer surface. An oxide film is often formed on the surface of the electrode connected by the conductive particles. By using conductive particles having conductive protrusions, by placing the conductive particles between the electrodes and pressing them, the protrusions effectively eliminate the oxide film. Therefore, the electrodes and the conductive particles can be more reliably brought into contact with each other, and the connection resistance between the electrodes can be further lowered. Furthermore, when the conductive particles have an insulating material on the surface, or when the conductive particles are dispersed in a resin and used as a conductive material, the projections between the conductive particles provide insulation between the conductive particles and the electrode. Substances or resins can be effectively eliminated. Therefore, the conduction reliability between the electrodes can be enhanced.

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

  The average height of the plurality of projections is preferably 0.001 μm or more, more preferably 0.05 μm or more, preferably 0.9 μm or less, more preferably 0.2 μm or less. The connection resistance between electrodes becomes effectively low that the average height of the said protrusion is more than the said minimum and below the said upper limit.

  From the viewpoint of effectively reducing the connection resistance and effectively increasing the connection reliability between the electrodes under high temperature and high humidity, the surface area of the portion where the protrusion is present in 100% of the total surface area of the outer surface of the gold layer Is preferably 10% or more, more preferably 20% or more, and still more preferably 30% or more. The upper limit of the ratio of the surface area of the portion where the protrusions are present to the total surface area of the outer surface of the gold layer is not particularly limited. The total surface area of the outer surface of the gold layer is preferably 100% or less, more preferably 95% or less, of the portion having the projections.

[Core substance]
By embedding the core substance in the conductive layer, it is easy for the conductive layer (the gold layer) to have a plurality of protrusions on the outer surface. However, in order to form protrusions on the outer surfaces of the conductive particles and the conductive layer, it is not necessary to necessarily use the core substance, and it is preferable not to use the core substance. The conductive particles preferably do not have a core material for raising the outer surface of the gold layer, and preferably do not have a core material for raising the outer surface of the nickel layer. However, the conductive particles may have a core material which raises the outer surface of the gold layer, and may have a core material which raises the outer surface of the nickel layer. When the core material is used, the core material is preferably disposed inside or inside the gold layer.

  As a method of forming the above-mentioned protrusion, after making a core substance adhere to the surface of substrate particles, a method of forming a conductive layer by electroless plating, and a conductive layer was formed by electroless plating on the surface of substrate particles Thereafter, a core material is attached, and further, a method of forming a conductive layer by electroless plating and the like can be mentioned. As another method of forming the projections, after forming a first conductive layer (such as a nickel layer) on the surface of the base particle, a core material is disposed on the first conductive layer, and then The method of forming the second conductive layer (gold layer etc.), and the method of adding the core substance in the process of forming the conductive layer (nickel layer or gold layer etc.) on the surface of the substrate particles .

  As a method of arranging the core substance on the surface of the above-mentioned base material particle, for example, the core substance is added to the dispersion liquid of the base material particle, and the core substance is added to the surface of the base material particle. And the core material is added to the container containing the substrate particles, and the core material is attached to the surface of the substrate particles by mechanical action such as rotation of the container. . Among them, a method in which the core substance is accumulated on the surface of the base material particles in the dispersion liquid and adhered is preferable because the amount of the core substance to be attached can be easily controlled.

  As a substance which comprises the said core substance, an electroconductive substance and a nonelectroconductive substance are mentioned. Examples of the conductive substance include metals, metal oxides, conductive nonmetals such as graphite, and conductive polymers. Examples of the conductive polymer include polyacetylene and the like. Examples of the nonconductive material include silica, alumina, barium titanate and zirconia. Among them, metals are preferable because the conductivity can be enhanced and the connection resistance can be effectively lowered. The core material is preferably metal particles.

  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. The alloy etc. which are comprised with two or more types of metals, such as an alloy, a tin-copper alloy, a tin-silver alloy, a tin-lead-silver alloy, and tungsten carbide, are mentioned. Among them, nickel, copper, silver or gold is preferable. The metal for forming the core material may be the same as or different from the metal for forming the conductive layer. It is preferable that the metal for forming the said core substance contains the metal for forming the said conductive layer. The metal for forming the core material preferably contains nickel. The metal for forming the core material preferably contains nickel.

  Specific examples of the material of the core material include barium titanate (Mohs hardness 4.5), nickel (Mohs hardness 5), silica (silicon dioxide, Mohs hardness 6 to 7), titanium oxide (Mohs hardness 7), zirconia (Mohrs hardness 8 to 9), alumina (Mohrs hardness 9), tungsten carbide (Mohrs hardness 9), diamond (Mohrs hardness 10) and the like. The inorganic particles are preferably nickel, silica, titanium oxide, zirconia, alumina, tungsten carbide or diamond, more preferably silica, titanium oxide, zirconia, alumina, tungsten carbide or diamond, titanium oxide, zirconia More preferably, they are alumina, tungsten carbide or diamond, particularly preferably zirconia, alumina, tungsten carbide or diamond. The Mohs hardness of the material of the core material is preferably 5 or more, more preferably 6 or more, still more preferably 7 or more, and particularly preferably 7.5 or more.

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

  The average diameter (average particle diameter) of the core substance is preferably 0.001 μm or more, more preferably 0.05 μm or more, preferably 0.9 μm or less, more preferably 0.2 μm or less. The connection resistance between electrodes becomes effectively low that the average diameter of the said core substance is more than the said minimum and below the said upper limit.

  The “average diameter (average particle diameter)” of the core substance indicates a number average diameter (number average particle diameter). The average diameter of the core substance can be determined by observing 50 arbitrary core substances with an electron microscope or an optical microscope and calculating the average value.

[Insulating material]
The conductive particles according to the present invention preferably include an insulating material disposed on the outer surface of the conductive layer (the gold layer). In this case, when conductive particles are used for connection between electrodes, a short circuit between adjacent electrodes can be prevented. Specifically, when a plurality of conductive particles are in contact with each other, an insulating material is present between the plurality of electrodes, so that it is possible to prevent a short circuit between adjacent electrodes in the lateral direction rather than between the upper and lower electrodes. In addition, at the time of connection between the electrodes, the insulating material between the conductive layer of the conductive particles and the electrodes can be easily removed by pressurizing the conductive particles with the two electrodes. When the conductive particle has a plurality of protrusions on the outer surface of the conductive layer, the insulating material between the conductive layer of the conductive particle and the electrode can be easily removed.

  The insulating material is preferably insulating particles, because the insulating material can be more easily removed at the time of pressure bonding between the electrodes.

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

  Examples of the above-mentioned polyolefins include polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer and the like. 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, SBS type styrene-butadiene block copolymer, and hydrogenated products thereof. Examples of the thermoplastic resin include vinyl polymers and vinyl copolymers. An epoxy resin, a phenol resin, a melamine resin etc. are mentioned as said thermosetting resin. Examples of the water-soluble resin include polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyvinyl pyrrolidone, polyethylene oxide and methyl cellulose. Among them, water-soluble resins are preferable, and polyvinyl alcohol is more preferable.

  Examples of the method of disposing the insulating material on the outer surface of the conductive layer include chemical methods and physical or mechanical methods. Examples of the chemical method include an interfacial polymerization method, a suspension polymerization method in the presence of particles, and an emulsion polymerization method. Examples of the physical or mechanical method include spray drying, hybridization, electrostatic deposition, spraying, dipping and vacuum deposition. Among them, a method in which the insulating material is disposed on the surface of the conductive layer via a chemical bond is preferable because the insulating material is hardly released.

  The outer surface of the conductive layer (the gold layer) and the surface of the insulating particles may be coated with a compound having a reactive functional group. The outer surface of the conductive layer and the surface of the insulating particle may not be directly chemically bonded, but may be indirectly chemically bonded by a compound having a reactive functional group. After introducing a carboxyl group to the outer surface of the conductive layer, the carboxyl group may be chemically bonded to a functional group on the surface of the insulating particle through a polymer electrolyte such as polyethylene imine.

  The average diameter (average particle diameter) of the insulating material can be appropriately selected depending on the particle diameter of the conductive particles, the use of the conductive particles, and the like. The average diameter (average particle diameter) of the insulating material is preferably 0.005 μm or more, more preferably 0.01 μm or more, preferably 1 μm or less, more preferably 0.5 μm or less. When the conductive particles are dispersed in the binder resin as the average diameter of the insulating substance is equal to or more than the above lower limit, the conductive layers in the plurality of conductive particles are less likely to contact with each other. When the average diameter of the insulating particles is not more than the above upper limit, it is not necessary to excessively increase the pressure in order to eliminate the insulating material between the electrodes and the conductive particles at the time of connection between the electrodes. There is no need to heat it.

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

[Anti-corrosion treatment]
In order to suppress the corrosion of the conductive particles and to reduce the connection resistance between the electrodes, the outer surface of the gold layer is subjected to anticorrosion treatment.

  From the viewpoint of further enhancing the conduction reliability, the outer surface of the gold layer is preferably subjected to an anticorrosion treatment with a compound having an alkyl group having 6 to 22 carbon atoms. The surface of the gold layer may be rustproofed by a compound not containing phosphorus, or may be rustproofed by a compound having an alkyl group of 6 to 22 carbon atoms and not containing phosphorus.

  From the viewpoint of further enhancing the conduction reliability, it is preferable that the outer surface of the gold layer is subjected to an anticorrosive treatment with an alkyl phosphate compound, an alkyl silane campling compound or an alkyl thiol. An antirust film can be formed on the outer surface of the gold layer by the antirust treatment.

  It is preferable that the said rustproof film is formed with the compound (Hereafter, it is also mentioned the compound A) which has a C6-C22 alkyl group. The outer surface of the gold layer is preferably surface-treated with the compound A. When the carbon number of the alkyl group is 6 or more, rusting is further less likely to occur in the entire conductive layer, and in particular, rusting in the nickel layer is even more difficult. The electroconductivity of electroconductive particle becomes high as carbon number of the said alkyl group is 22 or less. From the viewpoint of further enhancing the conductivity of the conductive particles, the carbon number of the alkyl group in the compound A is preferably 16 or less. The alkyl group may have a linear structure or may have a branched structure. The alkyl group preferably has a linear structure.

  The said compound A will not be specifically limited if it has a C6-C22 alkyl group. The compound A has a phosphoric acid ester having an alkyl group having 6 to 22 carbon atoms or a salt thereof, a phosphite ester having an alkyl group having 6 to 22 carbon atoms or a salt thereof, and an alkyl group having 6 to 22 carbon atoms It is preferable that it is at least 1 sort (s) selected from the group which consists of an alkoxysilane, the alkyl thiol which has a C6-C22 alkyl group, and the dialkyl disulfide which has a C6-C22 alkyl group. That is, the compound A having an alkyl group having 6 to 22 carbon atoms is at least one selected from the group consisting of phosphoric acid esters or salts thereof, phosphorous acid esters or salts thereof, alkoxysilanes, alkyl thiols and dialkyl disulfides. Is preferred. The use of these preferred compounds A can further reduce the occurrence of rust in the conductive layer. From the viewpoint of making rusting less likely to occur, the compound A is preferably the phosphate or salt thereof, a phosphite or salt thereof, or an alkylthiol, and the phosphate or salt thereof Or it is more preferable that it is phosphite ester or its salt. The compound A may be used alone or in combination of two or more.

  The compound A preferably has a reactive functional group capable of reacting with the outer surface of the nickel layer, and preferably has a reactive functional group capable of reacting with the outer surface of the gold layer. The compound A preferably has a reactive functional group capable of reacting with the insulating material. It is preferable that the anticorrosion film is chemically bonded to the gold layer. The rustproof film is preferably chemically bonded to the insulating material. More preferably, the anticorrosion film is chemically bonded to both the gold layer and the insulating material. Due to the presence of the reactive functional group and the chemical bond, peeling of the rustproof film is less likely to occur, and as a result, rust is less likely to occur on the gold layer, and the insulating material is isolated from the surface of the conductive particles. It becomes more difficult to detach unintentionally.

  Examples of the phosphate ester having an alkyl group having 6 to 22 carbon atoms or a salt thereof include hexyl phosphate ester, heptyl phosphate phosphate, monooctyl ester phosphate, monononyl phosphate phosphate, monodecyl ester phosphate, Phosphoric acid monoundecyl ester, phosphoric acid monododecyl ester, phosphoric acid monotridecyl ester, phosphoric acid monotetradecyl ester, phosphoric acid monopentadecyl ester, phosphoric acid monohexyl ester monosodium salt, phosphoric acid monoheptyl ester monosodium Salts, phosphoric acid monooctyl ester monosodium salt, phosphoric acid monononyl ester monosodium salt, phosphoric acid monodecyl ester monosodium salt, phosphoric acid monoundecyl ester monosodium salt, phosphoric acid monododecyl ester monosodium salt, Phosphate mono tridecyl ester monosodium salt, phosphate acid mono tetradecyl ester monosodium salt and phosphoric acid mono pentadecyl ester monosodium salt. You may use the potassium salt of the said phosphoric acid ester.

  Examples of the phosphite ester having an alkyl group having 6 to 22 carbon atoms or a salt thereof include hexyl phosphite ester, heptyl phosphite ester, monooctyl ester phosphite, monononyl phosphite, and phosphite Phosphoric acid monodecyl ester, phosphorous acid monoundecyl ester, phosphorous acid monododecyl ester, phosphorous acid monotridecyl ester, phosphorous acid monotetradecyl ester, phosphorous acid monopentadecyl ester, phosphoric acid monohexyl ester Ester monosodium salt, phosphorous acid monoheptyl ester monosodium salt, phosphorous acid monooctyl ester monosodium salt, phosphorous acid monononyl ester monosodium salt, phosphorous acid monodecyl ester monosodium salt, phosphorous acid monounne Decyl ester monosodium salt, phosphorous acid Dodecyl ester monosodium salt, phosphorous acid mono-tridecyl ester monosodium salt, phosphorous acid mono-tetradecyl ester monosodium salt and phosphorous acid mono-pentadecyl ester monosodium salt. You may use the potassium salt of the said phosphite.

  The alkoxysilane having an alkyl group having 6 to 22 carbon atoms is, for example, hexyltrimethoxysilane, hexyltriethoxysilane, heptyltrimethoxysilane, heptyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, nonyltrinylsilane. Methoxysilane, nonyltriethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, undecyltrimethoxysilane, undecyltriethoxysilane, dodecyltrimethoxysilane, dodecyltriethoxysilane, dodecyltriethoxysilane, tridecyltrimethoxysilane, tridecyltriethoxysilane Silane, tetradecyltrimethoxysilane, tetradecyltriethoxysilane, pentadecyltrimethoxysilane, pentadecyltriethoxysilane and the like can be mentioned.

  The alkylthiol having an alkyl group having 6 to 22 carbon atoms is, for example, hexylthiol, heptylthiol, octylthiol, nonylthiol, decylthiol, undecylthiol, dodecylthiol, tridecylthiol, tetradecylthiol, pentadecyl Thiol and hexadecyl thiol etc. are mentioned. The alkyl thiol preferably has a thiol group at the end of the alkyl chain.

  Examples of the dialkyl disulfide having an alkyl group having 6 to 22 carbon atoms include dihexyl disulfide, diheptyl disulfide, dioctyl disulfide, dinonyl disulfide, didecyl disulfide, diundecyl disulfide, didodecyl disulfide, ditridecyl disulfide, and ditetra Examples include decyl disulfide, dipentadecyl disulfide and dihexadecyl disulfide.

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

  The binder resin is not particularly limited. A well-known insulating resin is used as said binder resin.

  As said binder resin, a vinyl resin, a thermoplastic resin, curable resin, a thermoplastic block copolymer, an elastomer, etc. are mentioned, for example. 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 polyolefin resins, ethylene-vinyl acetate copolymers, and polyamide resins. As said curable resin, an epoxy resin, a urethane resin, a polyimide resin, 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 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, hydrogenated substance of styrene-butadiene-styrene block copolymer, and styrene-isoprene. -The hydrogenated substance of a styrene block copolymer, etc. are mentioned. Examples of the elastomer include styrene-butadiene copolymer rubber and acrylonitrile-styrene block copolymer rubber.

  In addition to the conductive particles and the binder resin, the conductive material is, for example, a filler, an extender, a softener, a plasticizer, a polymerization catalyst, a curing catalyst, a colorant, an antioxidant, a heat stabilizer, and light stability. Various additives such as agents, UV absorbers, lubricants, antistatic agents and flame retardants may be included.

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

  The content of the binder resin is preferably 10% by weight or more, more preferably 30% by weight or more, still more preferably 50% by weight or more, particularly preferably 70% by weight or more, and preferably 99% by weight in 100% by weight of the conductive material. It is 99 wt% or less, more preferably 99.9 wt% or less. When the content of the binder resin is not less than the lower limit and not more than the upper limit, conductive particles are efficiently disposed between the electrodes, and the connection reliability of the connection target member connected by the conductive material is further enhanced.

  The content of the conductive particles is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, preferably 40% by weight or less, and more preferably 20% by weight or less in 100% by weight of the conductive material. More preferably, it is 10% by weight or less. When the content of the conductive particles is not less than the lower limit and not more than the upper limit, conduction reliability between the electrodes is further enhanced.

(Connected structure)
A connection structure can be obtained by connecting members to be connected using the conductive particles or a conductive material containing the conductive particles and a binder resin.

  The connection structure includes a first connection target member, a second connection target member, and a connection portion connecting the first and second connection target members, and the connection portion has the above-described conductivity. It is preferable that it is a connection structure formed by the electrically-conductive material which is formed of particle | grains or which contains the electroconductive particle and binder resin which were mentioned above. When the conductive particles are used, the connection portion itself is the conductive particles. That is, the first and second connection target members are connected by the conductive particles.

  In FIG. 3, the connection structure using the electroconductive particle which concerns on the 1st Embodiment of this invention is shown typically by sectional drawing.

  The connection structure 51 shown in FIG. 3 includes a first connection target member 52, a second connection target member 53, and a connection portion 54 connecting the first and second connection target members 52 and 53. Prepare. The connection portion 54 is formed by curing a conductive material including the conductive particle 1. In FIG. 3, the conductive particles 1 are schematically illustrated for the convenience of illustration. Instead of the conductive particles 1, conductive particles 21 or the like may be used.

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

The manufacturing method of the said connection structure is not specifically limited. As an example of the manufacturing method of the connection structure, the conductive material is disposed between the first connection target member and the second connection target member, and after obtaining the laminate, the laminate is heated and pressed. Methods etc. The pressure of the said pressurization is about 9.8 * 10 < ⁴ > -4.9 * 10 < ⁶ > Pa. The temperature of the heating is about 120 to 220 ° C.

  Specific examples of the connection target member include electronic components such as a semiconductor chip, a capacitor, and a diode, and electronic components such as a printed circuit board, a flexible printed circuit, a circuit board such as a glass epoxy substrate and a glass substrate, and the like. The connection target member is preferably an electronic component. It is preferable that the said electroconductive particle is used for the electrical connection of the electrode in an electronic component.

  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 silver electrode, a molybdenum electrode, a tungsten electrode, etc. are mentioned. 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. In addition, when the said electrode is an aluminum electrode, the electrode formed only with aluminum may be sufficient, and the electrode by which the aluminum layer was laminated | stacked on the surface of a metal oxide layer may be sufficient. As a material of the said metal oxide layer, the indium oxide in which the trivalent metal element was doped, the zinc oxide in which the trivalent metal element was doped, etc. are mentioned. Sn, Al, Ga, etc. are mentioned as said trivalent metal element.

  Hereinafter, the present invention will be specifically described by way of examples and comparative examples. The invention is not limited to the following examples.

In order to obtain conductive particles, the following base particles were prepared.
Base particle A: resin particle; divinylbenzene copolymer resin particle having a particle diameter of 3.0 μm ("Micropearl SP-203" manufactured by Sekisui Chemical Co., Ltd.)
Base particle B: resin particle; resin particle having a particle diameter of 3.0 μm, prepared by polymerizing divinylbenzene and PTMGA (manufactured by Kyoeisha Chemical Co., Ltd.) at a weight ratio of 3: 7. Base particle C: resin particle; particle Divinylbenzene copolymer resin particles ("Micropearl SP-2025" manufactured by Sekisui Chemical Co., Ltd.) having a diameter of 2.5 μm
Base particle D: resin particle; divinylbenzene copolymer resin particle having a particle diameter of 10 μm ("Micropearl SP-210" manufactured by Sekisui Chemical Co., Ltd.)
Substrate particles E: organic-inorganic hybrid particles; organic-inorganic hybrid particles having a particle size of 3.0 μm (described in Example 13 described later)

The following rust inhibitors (compounds) were used for rustproofing.
Anticorrosion agent A: 2-ethylhexyl azido phosphate Anticorrosion agent B: lauryl azido phosphate Anticorrosion agent C: Stearyl amid phosphate Anticorrosion agent D: Top rinse (made by Okuno Pharmaceutical Co., Ltd.)

Example 1
(1) Formation of Nickel Layer After dispersing 10 parts by weight of the above-mentioned base particle A in 100 parts by weight of an alkaline solution containing 5% by weight of a palladium catalyst solution using an ultrasonic disperser, the solution is filtered. The base particle A was taken out. Then, the resin particles were added to 100 parts by weight of a 1% by weight solution of dimethylamine borane to activate the surface of the substrate particle A. After thoroughly washing the surface-activated substrate particles A, they were added to 500 parts by weight of distilled water and dispersed to obtain a suspension.

  In addition, a nickel plating solution (pH 9.0) containing 0.25 mol / L of nickel sulfate, 0.25 mol / L of sodium hypophosphite and 0.15 mol / L of sodium citrate was prepared.

  While stirring the obtained suspension at 70 ° C., the above-mentioned nickel plating solution was gradually dropped to the suspension to carry out electroless nickel plating. Thereafter, the suspension is filtered to take out the particles, washed with water, and dried to obtain particles in which a nickel-phosphorus conductive layer (thickness 0.1 μm) is disposed on the surface of the resin particles. The content of nickel in 100% by weight of the conductive layer was 97.6% by weight, and the content of phosphorus was 2.4% by weight.

(2) Formation of Gold Layer By performing electroless gold plating treatment, particles in which a gold layer (9 nm in thickness) was disposed on the outer surface of the above-mentioned nickel layer were obtained.

(3) Antirust Treatment The particles were dispersed using the above anticorrosion agent A to obtain conductive particles in which the outer surface of the gold layer was subjected to anticorrosion treatment.

(Example 2)
The pH 9.0 of the nickel plating solution was changed to pH 8.5, whereby the content of nickel in 100% by weight of the conductive layer was changed to 95.2% by weight, and the content of phosphorus was changed to 4.8% by weight Conductive particles were obtained in the same manner as Example 1 except for the above.

(Example 3)
Conductive particles were obtained in the same manner as in Example 1 except that rust inhibitor A was changed to rust inhibitor B.

(Example 4)
Conductive particles were obtained in the same manner as in Example 1 except that the rust preventive agent A was changed to the rust preventive agent C.

(Example 5)
Example 1 and Example 1 except that the thickness of the gold layer was changed to 14 nm, and the content of nickel in 100% by weight of the conductive layer was changed to 97.7% by weight and the content of phosphorus to 2.3% by weight In the same manner, conductive particles were obtained.

(Example 6)
(1) Formation of Nickel Layer After dispersing 10 parts by weight of the above-mentioned base particle A in 100 parts by weight of an alkaline solution containing 5% by weight of a palladium catalyst solution using an ultrasonic disperser, the solution is filtered. The base particle A was taken out. Subsequently, the substrate particle A was added to 100 parts by weight of a 1% by weight solution of dimethylamine borane to activate the surface of the substrate particle A. After thoroughly washing the surface-activated substrate particles A, they were added to 500 parts by weight of distilled water and dispersed to obtain a suspension.

  In addition, a nickel plating solution (pH 7.0) containing 0.25 mol / L nickel sulfate, 0.25 mol / L sodium hypophosphite, 0.15 mol / L sodium citrate and 0.12 mol / L sodium tungstate is prepared. did.

  While stirring the obtained suspension at 60 ° C., the above-mentioned nickel plating solution was gradually dropped to the suspension to carry out electroless nickel plating. Subsequently, a nickel plating solution (pH 10.0) containing 0.25 mol / L of nickel sulfate, 0.25 mol / L of sodium hypophosphite, 0.15 mol / L of sodium citrate and 0.12 mol / L of sodium tungstate is used. The suspension was gradually dropped and subjected to electroless nickel plating. Thereafter, the suspension was filtered to take out particles, washed with water, and dried to obtain particles in which a nickel-tungsten-phosphorus conductive layer (thickness 0.1 μm) was disposed on the surface of the substrate particle A. . The content of nickel in 100% by weight of the conductive layer was 82.1% by weight, the content of phosphorus was 2.3% by weight, and the content of tungsten was 15.6% by weight.

(2) Formation of Gold Layer By performing electroless gold plating treatment, particles in which a gold layer (9 nm in thickness) was disposed on the outer surface of the above-mentioned nickel layer were obtained.

(3) Antirust Treatment The particles were dispersed using the above anticorrosion agent A to obtain conductive particles in which the outer surface of the gold layer was subjected to anticorrosion treatment.

(Example 7)
The base particle A was etched and washed with water. Next, the base particle A was added to 100 mL of a palladium catalyst solution containing 8% by weight of a palladium catalyst and stirred. It was then filtered and washed. The base particle A was added to a 0.5 wt% dimethylamine borane solution of pH 6 to obtain a base particle A to which palladium was attached.

  The base material particle A to which palladium was attached was stirred in 300 mL of ion-exchanged water for 3 minutes to be dispersed to obtain a dispersion. Next, 1 g of metal nickel particle slurry (average particle diameter 100 nm) was added to the dispersion liquid over 3 minutes to obtain a substrate particle A to which a core substance was attached.

  A nickel layer and a gold layer were formed using the substrate particle A to which the core material was attached, and the content of nickel in 100% by weight of the conductive layer was 97.8% by weight, and the content of phosphorus was 1.2. Conductive particles were obtained in the same manner as in Example 1 except that the amount was changed to 2% by weight.

(Example 8)
100 mmol of methyl methacrylate, N, N, N-trimethyl-N-2-methacryloyloxyethyl in a 1000 mL separable flask equipped with a four-neck separable cover, a stirring blade, a three-way cock, a condenser and a temperature probe A monomer composition containing 1 mmol of ammonium chloride and 1 mmol of 2,2'-azobis (2-amidinopropane) dihydrochloride is weighed in ion-exchanged water so as to have a solid content of 5% by weight, and then 200 rpm Stir and carry out polymerization at 70 ° C. for 24 hours under a nitrogen atmosphere. After completion of the reaction, the resultant was lyophilized to obtain insulating particles having an ammonium group on the surface and having an average particle diameter of 220 nm and a CV value of 10%.

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

  10 g of the conductive particles obtained in Example 7 were dispersed in 500 mL of ion exchanged water, 4 g of a water dispersion of insulating particles was added, and the mixture was stirred at room temperature for 6 hours. After filtration through a 3 μm mesh filter, the resultant was further washed with methanol and dried to obtain conductive particles to which insulating particles are attached.

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

  The same as Example 1, except that the insulating particles were used, and the content of nickel in 100% by weight of the conductive layer was changed to 97.8% by weight and the content of phosphorus to 2.2% by weight. , Conductive particles were obtained.

(Example 9)
Conductive particles were obtained in the same manner as in Example 1 except that the base material particle A was changed to the base material particle B.

(Comparative example 1)
The pH 9.0 of the nickel plating solution was changed to pH 7.0, whereby the content of nickel in 100% by weight of the conductive layer was changed to 92.5% by weight, and the content of phosphorus was changed to 7.5% by weight Conductive particles were obtained in the same manner as Example 1 except for the above.

(Comparative example 2)
Example 6 is the same as Example 1 except that the anticorrosion treatment was not performed, and the content of nickel in 100% by weight of the conductive layer was changed to 97.7% by weight, and the content of phosphorus in 2.3% by weight. Thus, conductive particles were obtained.

(Comparative example 3)
Example 1 and Example 1 except that the thickness of the gold layer was changed to 18 nm, and the content of nickel in 100% by weight of the conductive layer was changed to 97.7% by weight and the content of phosphorus to 2.3% by weight In the same manner, conductive particles were obtained.

(Example 10)
Conductive particles were obtained in the same manner as in Example 1 except that the rust inhibitor A was changed to the rust inhibitor D.

(Example 11)
Conducted except that the substrate particle A was changed to the substrate particle C, and the content of nickel in 100% by weight of the conductive layer was changed to 97.5% by weight, and the content of phosphorus to 2.5% by weight Conductive particles were obtained in the same manner as Example 1.

(Example 12)
Conducted except that the substrate particle A was changed to the substrate particle D, and the content of nickel in 100% by weight of the conductive layer was changed to 97.9% by weight, and the content of phosphorus to 2.1% by weight Conductive particles were obtained in the same manner as Example 1.

(Example 13)
In a 500 mL reaction vessel equipped with a stirrer and a thermometer, 300 g of a 0.13% by weight aqueous ammonia solution was placed. Next, 4.1 g of methyltrimethoxysilane, 19.2 g of vinyltrimethoxysilane, and 0.7 g of a silicone alkoxy oligomer ("X-41-1053" manufactured by Shin-Etsu Chemical Co., Ltd.) in an aqueous ammonia solution in a reaction vessel The mixture with was slowly added. After the hydrolysis and condensation reaction proceed with stirring, 2.4 mL of a 25 wt% aqueous ammonia solution is added, and then the particles are isolated from the aqueous ammonia solution, and the particles obtained are subjected to an oxygen partial pressure of 10 ^-17 atm. The mixture was calcined at 350 ° C. for 2 hours to obtain organic-inorganic hybrid particles having a particle diameter of 3.0 μm. Except that the obtained organic hybrid particles were used as the substrate particles E, and the content of nickel in 100% by weight of the conductive layer was changed to 97.7% by weight and the content of phosphorus to 2.3% by weight In the same manner as in Example 1, conductive particles were obtained.

(Example 14)
An electroless nickel plating solution containing 0.25 mol / L of sodium hypophosphite was prepared.

  Further, a plating solution for protrusion formation containing 0.25 mol / L of sodium hypophosphite and 0.05 mol / L of sodium hydroxide was prepared.

  An electroless plating process was performed using the base particle A and the electroless nickel plating solution in the previous period. Next, in order to form protrusions on the conductive layer, a plating solution for forming protrusions was gradually dropped to form protrusions. Nickel plating was performed while dispersing the Ni protrusion nuclei generated in the plating solution by ultrasonic agitation. By performing electroless plating using the above-mentioned late electroless nickel plating solution, particles in which a nickel layer (nickel-phosphorus alloy layer, thickness 80 nm) and precipitation protrusions were formed on the surface of the resin particles were obtained. The content of nickel in 100% by weight of the conductive layer was 97.9% by weight, and the content of phosphorus was 2.1% by weight.

  Thereafter, a gold layer was formed in the same manner as in Example 1 to obtain conductive particles.

(Example 15)
An electroless nickel plating solution containing 0.75 mol / L of sodium hypophosphite was prepared.

  Further, a plating solution for protrusion formation containing 0.25 mol / L of sodium hypophosphite and 0.05 mol / L of sodium hydroxide was prepared.

  An electroless plating process was performed using the base particle A and the electroless nickel plating solution in the previous period. Next, in order to form protrusions on the conductive layer, a plating solution for forming protrusions was gradually dropped to form protrusions. Nickel plating was performed while dispersing the Ni protrusion nuclei generated in the plating solution by ultrasonic agitation. By performing electroless plating using the above-mentioned late electroless nickel plating solution, particles in which a nickel layer (nickel-phosphorus alloy layer, thickness 80 nm) and precipitation protrusions were formed on the surface of the resin particles were obtained. The content of nickel in 100% by weight of the conductive layer was 97.9% by weight, and the content of phosphorus was 2.1% by weight.

  Thereafter, a gold layer was formed in the same manner as in Example 1 to obtain conductive particles.

(Example 16)
At the time of formation of the nickel layer, 0.10 mol / L of sodium tungstate was added to the nickel plating solution, whereby the content of nickel in 100% by weight of the conductive layer was 97.1% by weight, and the content of phosphorus was 1. Particles in which a nickel layer (nickel-phosphorus-tungsten alloy layer, thickness 80 nm) was formed were obtained in the same manner as in Example 1 except that the content was changed to 9 wt% and 1.0 wt% of tungsten.

  Thereafter, a gold layer was formed in the same manner as in Example 1 to obtain conductive particles.

(Evaluation)
(1) Content of Nickel, Phosphorus and Tungsten in 100% by Weight of Nickel Layer (Conductive Layer) A thin film slice of the obtained conductive particles was produced using a focused ion beam. Each content of nickel, phosphorus, and tungsten in the conductive layer was measured by an energy dispersive X-ray analyzer (EDS) using a transmission electron microscope FE-TEM ("JEM-2010 FEF" manufactured by JEOL Ltd.). The content in the entire nickel layer was determined.

(2) Initial connection resistance The conductive particles thus obtained are added to “Structbond XN-5A” manufactured by Mitsui Chemicals, Inc. so that the content is 10% by weight, and dispersed to obtain an anisotropic conductive paste. Made.

  A transparent glass substrate having an ITO electrode pattern with L / S of 20 μm / 20 μm on the top was prepared. In addition, a semiconductor chip having a gold electrode pattern with L / S of 20 μm / 20 μm on the lower surface was prepared.

  On the transparent glass substrate, an anisotropic conductive paste immediately after preparation was applied to a thickness of 30 μm to form an anisotropic conductive paste layer. Next, the said semiconductor chip was laminated | stacked so that electrodes might oppose on the anisotropic conductive paste layer. Thereafter, while adjusting the temperature of the head so that the temperature of the anisotropic conductive paste layer is 185 ° C., the pressure heating head is placed on the upper surface of the semiconductor chip, and a pressure of 1 MPa is applied to the anisotropic conductive paste layer. It was cured at 185 ° C. to obtain a connection structure.

  The connection resistance between the upper and lower electrodes of the obtained connection structure was measured by the four-terminal method. The average value of two connection resistances was calculated. The connection resistance can be determined from the relationship of voltage = current × resistance by measuring the voltage when a constant current flows. The initial connection resistance was determined based on the following criteria.

[Criteria for initial connection resistance]
○○: Connection resistance is 2.0Ω or less ○: Connection resistance is over 2.0Ω, 3.0Ω or less Δ: Connection resistance is over 3.0Ω, 5.0Ω or less ×: Connection resistance is over 5.0Ω

(3) Connection resistance after reliability test (Conduction reliability)
The connection structure obtained by the evaluation of the connection resistance in the above (2) initial stage was left under the conditions of 85 ° C. and 85% relative humidity. After 150 hours from the start of standing, the connection resistance between the electrodes was measured by the four-terminal method in the same manner as the evaluation of the connection resistance in the above (2) initial stage. The connection resistance after the reliability test was determined based on the following criteria.

[Criteria for connection resistance after reliability test]
○: The average value of connection resistance (after leaving) is less than 125% compared to the average value of connection resistance (before leaving) ○: The average value of connection resistance (after leaving) compared to the average value of connection resistance (before leaving) Value: 125% or more, less than 150% Δ: The average value of connection resistance (after leaving) is 150% or more, less than 200% compared to the average value of connection resistance (before leaving) ×: Average of connection resistance (before leaving) The average value of connection resistance (after leaving) is 200% or more compared to the value

  The results are shown in Table 1 below.

  In the evaluation of connection resistance after the above (3) reliability test, the obtained connection structure was left at 85 ° C. and 85% relative humidity. Even after the conductive structure is obtained under the condition of 85 ° C. and 85% relative humidity before obtaining the connection structure, the connection resistance tends to increase even after the connection structure is obtained after the above (3) reliability test. The same tendency as the evaluation result of the connection resistance was observed. In Examples 14 and 15, of 100% of the total surface area of the outer surface of the gold layer, the surface area of the portion with projections was 30% or more.

DESCRIPTION OF SYMBOLS 1 ... Conductive particle 2 ... Base material particle 3 ... Nickel layer 4 ... Gold layer 21 ... Conductive particle 21a ... Protrusion 22 ... Nickel layer 22a ... Protrusion 23 ... Gold layer 23a ... Protrusion 24 ... Core material 25 ... Insulation material 51 ... Connection structure 52 ... first connection target member 52a ... first electrode 53 ... second connection target member 53a ... second electrode 54 ... connection portion

Claims (12)

Substrate particles,
A nickel layer disposed on the surface of the base particle and containing nickel and phosphorus; and a gold layer disposed on the outer surface of the nickel layer and containing gold,
The content of phosphorus is less than 5% by weight in 100% by weight of the entire nickel layer,
The thickness of the gold layer is less than 15 nm,
Conductive particles in which the outer surface of the gold layer is treated to prevent corrosion.   The conductive particle according to claim 1, wherein the thickness of the gold layer is 10 nm or less.   The electroconductive particle of Claim 1 or 2 whose antirust process is carried out by the compound which has a C6-C22 alkyl group in the outer surface of the said gold layer.   The conductivity according to any one of claims 1 to 3, wherein in the thickness direction of the nickel layer, phosphorus is unevenly distributed so that more phosphorus is present on the gold layer side than on the base particle side. particle.   The electroconductive particle of any one of Claims 1-4 in which the outer surface of the said gold layer is rustproofed by the compound which does not contain phosphorus.   The electroconductive particle of any one of Claims 1-5 which has several protrusion in the outer surface of the said gold layer.   The conductive particle according to claim 6, comprising a plurality of core materials that raise the outer surface of the gold layer to form a plurality of the protrusions.   The conductive particle according to claim 7, wherein the material of the core material has a Mohs hardness of 5 or more.   The conductive particle according to any one of claims 6 to 8, wherein the surface area of the portion with the projections is 30% or more in 100% of the total surface area of the outer surface of the gold layer.   The conductive particle according to any one of claims 1 to 9, comprising an insulating material disposed on the outer surface of the gold layer.   The electrically conductive material containing the electroconductive particle of any one of Claims 1-10, and binder resin. A first connection target member having a first electrode on the surface;
A second connection target member having a second electrode on its surface;
A connecting portion connecting the first connection target member and the second connection target member;
The connection portion is formed of the conductive particles according to any one of claims 1 to 10, or is formed of a conductive material containing the conductive particles and a binder resin,
The connection structure which the said 1st electrode and the said 2nd electrode are electrically connected by the said electroconductive particle.

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