JP2015109268A - Conductive particle, conductive material, and connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide electrical conductive particles capable of reducing a connection resistance between electrodes when connecting between the electrodes and enhancing connection reliability between the electrodes at high temperature and high humidity.SOLUTION: A conductive particle 1 includes: a base particle 2; a nickel layer 3 arranged on a surface of the base particle, 2 and containing nickel and phosphorus; and a gold layer 4 arranged on an outer surface of the nickel layer 3, and containing gold. A content of phosphorus is less than 5 wt.% in whole 100 wt.% of the nickel layer 3, a thickness of the gold layer 4 is less than 15 nm, and an outer surface of the gold layer 4 is subjected to rust preventive treatment.

Description

  The present invention relates to conductive particles 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 connection structure using the conductive particles.

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

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

  As an example of the conductive particles, Patent Document 1 listed below discloses conductive particles including a nickel layer and a gold layer formed on the nickel layer and having an average film thickness of 300 mm or less. ing. In this conductive particle, the gold layer is the outermost layer. Moreover, in this electroconductive particle, the elemental composition ratio (Ni / Au) of nickel and gold in the surface of the electroconductive particle by X-ray photoelectron spectroscopy analysis is 0.4 or less. In the example 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.

  In Examples of Patent Document 2 below, conductive particles in which a nickel plating layer is formed on the surface of the crosslinked polystyrene particles and a gold plating layer is formed on the outer surface of the nickel plating layer are disclosed. Yes. In the example 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 including core particles, a Ni plating layer, a noble metal plating layer, and a rust preventive film. The Ni plating layer covers the core particles and contains Ni. The noble metal plating layer covers at least a part of the Ni plating layer and includes at least one of Au and Pd. The rust preventive 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 conventional conductive particles as described in Patent Documents 1 to 3 are used to electrically connect electrodes to obtain a connection structure, connection resistance may be increased. Further, when conductive particles exposed to high temperature and high humidity are used, or connection structures using conductive particles are exposed to high temperature and high humidity, there is a problem that the connection resistance tends to increase.

  An object of the present invention is to provide conductive particles capable of reducing the connection resistance when the electrodes are electrically connected and improving the connection reliability between the electrodes under high temperature and high humidity. That is. Another object of the present invention is to provide a conductive material and a connection structure using the conductive particles.

  According to a wide aspect of the present invention, the base material particles are disposed on the surface of the base material particles, and the nickel layer containing nickel and phosphorus is disposed on the outer surface of the nickel layer, And a gold layer containing gold, and in 100% by weight of the total nickel layer, the phosphorus content is less than 5% by weight, the thickness of the gold layer is less than 15 nm, and the outer surface of the gold layer is Conductive particles are provided that are anti-rust treated.

  On the specific situation with the electroconductive particle which concerns on this invention, the thickness of the said gold layer is 10 nm or less.

  On the specific situation with the electroconductive particle which concerns on this invention, the outer surface of the said gold layer is rust-proofed with the compound which has a C6-C22 alkyl group.

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

  On the specific situation with the electroconductive particle which concerns on this invention, the outer surface of the said gold layer is rust-proofed with the compound which does not contain phosphorus.

  On the specific situation with the electroconductive particle which concerns on this invention, the said electroconductive particle has several protrusion on the outer surface of the said gold layer.

  On the specific situation with the electroconductive particle which concerns on this invention, the said electroconductive particle is provided with the some core substance which makes the outer surface of the said gold layer protrude so that the said some protrusion may be formed.

  On the specific situation with the electroconductive particle which concerns on this invention, the Mohs hardness of the material of the said core substance is 5 or more.

  On the specific situation with the electroconductive particle which concerns on this invention, the surface area of the part with the said protrusion is 30% or more in the total surface area 100% of the outer surface of the said gold layer.

  On the specific situation with the electroconductive particle which concerns on this invention, the said electroconductive particle is equipped with the insulating substance arrange | positioned on the outer surface of the said gold layer.

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

  According to a wide 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 A connection portion connecting the second connection target member, and the connection portion is formed of the above-described conductive particles or formed of a conductive material including the conductive particles and a binder resin. There is provided a connection structure 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 the surface of the base material particle, the base material particle, and the nickel layer containing nickel and phosphorus, and the outer surface of the nickel layer, And a gold layer containing gold, and in 100 wt% of the nickel layer as a whole, the phosphorus content is less than 5 wt%, the thickness of the gold layer is less than 15 nm, and the gold layer Since the outer surface of the electrode is rust-proof, when the electrodes are electrically connected using the conductive particles according to the present invention, the connection resistance can be lowered, and the electrode under high temperature and high humidity Connection reliability can be increased.

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

  Details of the present invention will be described below.

(Conductive particles)
The electroconductive particle which concerns on this invention is equipped with a base material particle, the nickel layer arrange | positioned on the surface of the said base material particle, and the gold layer arrange | positioned on the outer surface of the said nickel layer. The nickel layer includes nickel and phosphorus. The gold layer includes gold.

  In the electroconductive particle which concerns on this invention, content of phosphorus is less than 5 weight% in 100 weight% of the whole nickel layer. Furthermore, in the electroconductive particle which concerns on this invention, the thickness of the said gold layer is less than 15 nm. Furthermore, in the electroconductive particle which concerns on this invention, the outer surface of the said gold layer is rust-proofed.

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

  When the thickness of the gold layer is 15 nm or more, even if the connection resistance between the electrodes and the connection reliability between the electrodes under high temperature and high humidity are not a problem, the thickness of the gold layer is less than 15 nm. In some cases, the connection resistance between the electrodes and the connection reliability between the electrodes under high temperature and high humidity may be serious problems. In the present invention, even if the thickness of the gold layer is less than 15 nm, the phosphorous content is less than 5% by weight in the total 100% by weight of the nickel layer, and the outer surface of the gold layer is rust-proofed. Therefore, 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 improved.

  In the present invention, an increase in connection resistance can be suppressed when a connection structure is produced using conductive particles stored for a long time under high temperature and high humidity. Further, even when the connection structure is stored for a long time under high temperature and high humidity, an increase in connection resistance can be suppressed. In particular, in the conductive particles according to the present invention, the outer surface of the gold layer is rust-proofed, so that the thickness of the gold layer is thin and the connection is made even though there is a nickel layer inside the gold layer. An increase in resistance can be suppressed. Further, since the gold layer is quite thin, the nickel particles may be partially exposed in the conductive particles due to the presence of pinholes or the like, and the nickel layer is likely to be partially exposed. Even if the nickel layer is partially exposed, an increase in connection resistance can be suppressed because the outer surface of the gold layer is rust-proofed.

  The conductive particles include, for example, a step of disposing the nickel layer on the surface of the substrate particle, a step of disposing the gold layer on the outer surface of the nickel layer, and an outer surface of the gold layer. It can be obtained through a process of rust treatment.

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

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

  As shown in FIG. 1, the conductive particle 1 includes a base particle 2, a nickel layer 3, and a gold layer 4. The nickel layer 3 contains nickel and phosphorus. The gold layer 4 contains gold. The content of phosphorus is less than 5% by weight in the total 100% by weight 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 particles 1, a multi-layered 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. The gold layer 4 is disposed on the outer surface of the nickel layer 3. The conductive particle 1 is a coated particle in which the surface of the base particle 2 is coated with the nickel layer 3 and the gold layer 4.

  Although not shown, the outer surface of the gold layer 4 is rust-proofed. Therefore, the conductive particle 1 includes a rust preventive film on the outer surface of the gold layer 4.

  The conductive particles 1 do not have a core substance. The conductive particles 1 do not have protrusions on the conductive surface. The conductive particles 1 are spherical. The nickel layer 3 and the gold layer 4 do not have protrusions on the outer surface. Thus, the electroconductive particle which concerns on this invention does not need to have a processus | protrusion on the electroconductive surface, and may be spherical. Moreover, the electroconductive particle 1 does 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.

  Further, 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 base particle 2 and the nickel layer 3. On the surface of the base particle 2, the nickel layer 3 may be disposed via another conductive layer.

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

  A conductive particle 21 shown in FIG. 2 includes a base particle 2, a nickel layer 22, a gold layer 23, a core substance 24, and an insulating substance 25. The nickel layer 22 includes 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. The gold layer 23 is disposed on the outer surface of the nickel layer 22.

  Although not shown, the outer surface of the gold layer 23 is rust-proofed. Therefore, the conductive particles 21 include a rust preventive film on the outer surface of the gold layer 23.

  The conductive particles 21 have protrusions 21a on the conductive surface. There are a plurality of protrusions 21a. 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 arranged 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 substance 24 is disposed inside the protrusions 21a, 22a, and 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 a plurality of core materials 24, and protrusions 21a, 22a, and 23a are formed. Thus, the electroconductive particle which concerns on this invention may have a processus | protrusion on the electroconductive surface. The conductive particles according to the present invention may have protrusions on the outer surface of the conductive layer. Moreover, the electroconductive particle which concerns on this invention does not have a processus | protrusion on the outer surface of a nickel layer, and may have a processus | protrusion on the outer surface of a gold layer. The electroconductive particle which concerns on this invention may be provided with the some core substance which has raised the surface of the gold layer so that several protrusion may be formed in the inside or inside of a gold layer. The core substance may be located inside the nickel layer or may be located 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 part of the outer surface of the gold layer 23 is covered with an insulating material 25. The insulating substance 25 is made of an insulating material and is an insulating particle. Thus, the electroconductive particle which concerns on this invention may have the insulating substance arrange | positioned on the outer surface of a gold layer.

  Hereinafter, the details of the substrate particles and the conductive layer will be described.

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

  The substrate particles are more preferably resin particles or organic-inorganic hybrid particles, and may be resin particles or organic-inorganic hybrid particles. By using these preferable base particles, conductive particles more suitable for electrical connection between the electrodes can be obtained.

  When connecting between electrodes using the said electroconductive particle, after arrange | positioning the said electroconductive particle between electrodes, the said electroconductive particle is compressed by crimping | bonding. When the substrate particles are resin particles 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 is increased. For this reason, the connection resistance between electrodes becomes still lower.

  Various organic materials are suitably used as the resin for forming the resin particles. Examples of the resin for forming the resin particles include polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, 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, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polysulfone, polyphenylene Oxide, polyacetal, polyimide, polyamideimide, 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. Resin for forming the resin particles can be designed and synthesized, and the hardness of the base particles can be easily controlled within a suitable range, which is suitable for conductive materials and having physical properties at the time of compression. Is preferably a polymer obtained by polymerizing one or more polymerizable monomers having a plurality of ethylenically unsaturated groups.

  When the resin particles are obtained by polymerizing a monomer having an ethylenically unsaturated group, the monomer having the ethylenically unsaturated group may be a non-crosslinkable monomer or a crosslinkable monomer. And a polymer.

  Examples of the non-crosslinkable monomer include styrene monomers such as styrene and α-methylstyrene; carboxyl group-containing monomers such as (meth) acrylic acid, maleic acid, and maleic anhydride; (Meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl ( Alkyl (meth) acrylates such as meth) acrylate and isobornyl (meth) acrylate; 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, propyl vinyl ether; vinyl acids such as vinyl acetate, vinyl butyrate, vinyl laurate, vinyl stearate Esters; Unsaturated hydrocarbons such as ethylene, propylene, isoprene and butadiene; Halogen-containing monomers such as trifluoromethyl (meth) acrylate, pentafluoroethyl (meth) acrylate, vinyl chloride, vinyl fluoride and chlorostyrene Is mentioned.

  Examples of the crosslinkable monomer include tetramethylolmethane tetra (meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolmethane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and dipenta Erythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, glycerol tri (meth) acrylate, glycerol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) Polyfunctional (meth) acrylates such as acrylate, (poly) tetramethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate; triallyl (iso) cyanure Silane-containing monomers such as triallyl trimellitate, divinylbenzene, diallyl phthalate, diallylacrylamide, diallyl ether, γ- (meth) acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, vinyltrimethoxysilane It is done.

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

  In the case where the substrate particles are inorganic particles or organic-inorganic hybrid particles excluding metal particles, examples of the inorganic material for forming the substrate particles include silica, alumina, barium titanate, zirconia, and carbon black. . The inorganic substance is preferably not a metal. The particles formed by the 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, firing may be performed as necessary. The particle | grains obtained by performing are mentioned. Examples of the organic / inorganic hybrid particles include organic / inorganic hybrid particles formed of a crosslinked alkoxysilyl polymer and an acrylic resin.

  The organic-inorganic hybrid particles are preferably core-shell type organic-inorganic hybrid particles having a core and a shell disposed on the surface of the core. The core is preferably an organic core. The shell is preferably an inorganic shell. From the viewpoint of effectively reducing the connection resistance between the electrodes, the base material particles are preferably organic-inorganic hybrid particles having an organic core and an inorganic shell disposed on the surface of the organic core.

  Examples of the material for forming the organic core include the resin for forming the resin particles described above.

  Examples of the material for forming the inorganic shell include inorganic substances for forming the above-described base material particles. 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-like material by a sol-gel method and then firing the shell-like material. The metal alkoxide is preferably a silane alkoxide. The inorganic shell is preferably formed of a silane alkoxide.

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

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

  The particle diameter of the base particle indicates a diameter when the base particle is a true sphere, and indicates a maximum diameter when the base particle is not a true sphere.

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

  Examples of metals other than nickel in the nickel layer include silver, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, palladium, chromium, titanium, antimony, bismuth, thallium, germanium, cadmium, silicon, and tungsten. Molybdenum, tin-doped indium oxide (ITO), and the like. As for these metals, only 1 type may be used and 2 or more types may be used together. Since the conductive layer and the protrusion are effectively hardened, the nickel layer preferably contains tungsten. When the conductive layer and the protrusions are hardened, the oxide film is easily removed effectively.

  The nickel layer preferably contains nickel as a main metal. The content of nickel is preferably 50% by weight or more in 100% by weight of the entire nickel layer. In 100% by weight of the entire nickel layer, the nickel content is preferably 65% by weight or more, more preferably 80% by weight or more, and still more preferably 90% by weight or more. When the nickel content is at least the above lower limit, the connection resistance between the electrodes is further reduced.

  In order to reduce the connection resistance between the electrodes and increase 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. Less than% by weight. 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 content of phosphorus is 0% in 100% by weight of the entire nickel layer. %, More preferably 0.1% by weight or more, still more preferably 2% by weight or more. When the phosphorus content is not less than the above lower limit, the connection resistance is further reduced. From the viewpoint of further lowering the connection resistance, the phosphorus content is preferably 4.9% by weight or less, more preferably 4% by weight or less, and even more preferably 3% by weight or less in 100% by weight of the entire nickel layer. is there.

  In the thickness direction of the nickel layer, the phosphorus content may have a gradient so that the phosphorus content on the gold layer side (outside) is higher than the phosphorus content on the base particle side (inside). preferable. In the thickness direction of the nickel layer, phosphorus is preferably unevenly distributed so that more phosphorus is present on the gold layer side than on the base particle side. The existence of such a concentration gradient further increases the reliability of the connection resistance.

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

  The absolute value of the difference between the phosphorus content in the entire region having a thickness of 1/2 on the substrate particle side and the phosphorus content in the entire region having a thickness of 1/2 on the gold layer side is preferably 2% by weight. Above, more preferably 5% by weight or more, still more preferably 10% by weight or more, and preferably 19% by weight or less. When the absolute value of the difference in phosphorus content is not less than the above lower limit and not more than the above upper limit, the reliability of connection resistance is further enhanced.

  The thickness of the nickel layer is preferably 30 nm or more, more preferably 60 nm or more, preferably 200 nm or less, more preferably 100 nm or less. When the thickness of the nickel layer is not less than the above lower limit and not more than the above upper limit, the oxide film on the surface of the electrode is more effectively removed, and the connection resistance between the electrodes is further reduced. The thickness of the said nickel layer shows the average thickness of the nickel layer in electroconductive particle.

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

  Examples of the metal other than gold in the gold layer include, for example, silver, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, palladium, chromium, titanium, antimony, bismuth, thallium, germanium, and cadmium. , Silicon, tungsten, molybdenum, tin-doped indium oxide (ITO), and the like. As for these metals, only 1 type may be used and 2 or more types may be used together.

  The gold layer preferably contains gold as a main metal. The gold content is preferably 50% by weight or more in 100% by weight of the entire gold layer. In 100% by weight of the entire gold layer, the gold content is preferably 90% by weight or more, more preferably 95% by weight or more, and still more preferably 99.9% by weight or more. When the gold content is not less than the above lower limit, the electrode and the conductive particles are more appropriately brought into contact with each other, and the connection resistance between the electrodes is further reduced.

  The gold layer has a thickness of less than 15 nm, more preferably 10 nm or less, still more 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 above lower limit and not more than the above upper limit, an increase in connection resistance is effectively suppressed. In the conductive particles according to the present invention, even if the gold layer is thin, the gold layer is dense, so that the connection resistance between the electrodes can be lowered, and the variation in the connection resistance between the electrodes is suppressed. be able to. Moreover, even if the thickness of the gold layer is less than 10 nm and the thickness of the gold layer is considerably thin, the gold layer is thin and the outer surface of the gold layer is treated with rust prevention. Despite the nickel layer inside the gold layer, an increase in connection resistance can be suppressed. Further, the gold layer may not be a continuous film. In this case, the thickness of the gold layer is less than 15 nm and the outer surface of the gold layer is rust-proofed. Despite being thin and having a nickel layer inside the gold layer, an increase in connection resistance can be suppressed.

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

  Examples of a method for controlling the nickel and phosphorus contents in the conductive layer include, for example, a method of controlling the pH of a nickel plating solution when forming a conductive layer by electroless nickel plating, and a conductive layer by electroless nickel plating. The method of adjusting the density | concentration of a phosphorus containing reducing agent, the method of adjusting the nickel density | concentration in a nickel plating solution, etc. are mentioned when forming.

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

  As a method of forming the catalyst on the surface of the resin particles, for example, after adding the resin particles to a solution containing palladium chloride and tin chloride, the surface of the resin particles is activated with an acid solution or an alkali solution, A method of depositing palladium on the surface of the resin particles, and after adding the resin particles to a solution containing palladium sulfate and aminopyridine, the surface of the resin particles is activated by a solution containing a reducing agent. Examples thereof include a method of depositing palladium on the surface. As the reducing agent, a phosphorus-containing reducing agent is preferably used.

  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 the nickel plating bath, nickel can be deposited on the surface of the resin particles on which the catalyst is formed, 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.

  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 even more preferably 5 μm or less. When the particle diameter of the conductive particles is not less than the above lower limit and not more than the above upper limit, when the electrodes are connected using the conductive particles, the contact area between the conductive particles and the electrode becomes sufficiently large, and the conductive Aggregated conductive particles are less likely to be formed when the layer is formed. Further, the distance between the electrodes connected via the conductive particles does not become too large, and the conductive layer is difficult to peel from the surface of the base material particles. The particle diameter of the conductive particles is also preferably 3 μm or less.

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

  The conductive particles according to the present invention preferably have protrusions 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, the oxide particles are effectively eliminated by the protrusions by placing the conductive particles between the electrodes and then pressing them. For this reason, an electrode and electroconductive particle can be contacted still more reliably and the connection resistance between electrodes can be made still lower. Further, when the conductive particles have an insulating material on the surface, or when the conductive particles are dispersed in the resin and used as a conductive material, the conductive particles and the electrodes are insulated by the protrusions of the conductive particles. Substances or resins can be effectively excluded. For this reason, the conduction | electrical_connection reliability between electrodes can be improved.

  It is preferable that there are a plurality of protrusions. The number of protrusions 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 protrusions 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.

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

  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 proportion of 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 not particularly limited. Of the total surface area of 100% of the outer surface of the gold layer, the surface area of the portion having the protrusions is preferably 99% or less, more preferably 95% or less.

[Core material]
Since the core substance is embedded 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 always necessary to use a core substance, and it is preferable not to use a 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 that bulges the outer surface of the gold layer, or may have a core material that bulges 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 the method for forming the protrusions, a core material is attached to the surface of the base particle, and then a conductive layer is formed by electroless plating, and a conductive layer is formed on the surface of the base particle by electroless plating. Thereafter, a method of attaching a core substance and further forming a conductive layer by electroless plating may be used. As another method for forming the protrusions, a first conductive layer (such as a nickel layer) is formed on the surface of the base particle, and then a core substance is disposed on the first conductive layer. Examples include a method of forming the second conductive layer (gold layer, etc.) and a method of adding a core substance in the middle of forming a conductive layer (nickel layer, gold layer, etc.) on the surface of the base material particles. .

  As a method of disposing the core substance on the surface of the base particle, for example, the core substance is added to the dispersion of the base particle, and the core substance is applied to the surface of the base particle, for example, van der Waals force. And a method in which a core substance is added to a container containing base particles, and a core substance is attached to the surface of the base particles by mechanical action such as rotation of the container. . Especially, since the quantity of the core substance to adhere is easy to control, the method of making a core substance accumulate and adhere on the surface of the base particle in a dispersion liquid is preferable.

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

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

  Specific examples of the core material include barium titanate (Mohs hardness 4.5), nickel (Mohs hardness 5), silica (silicon dioxide, Mohs hardness 6-7), titanium oxide (Mohs hardness 7), zirconia. (Mohs hardness 8-9), alumina (Mohs hardness 9), tungsten carbide (Mohs hardness 9), diamond (Mohs 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. Alumina, tungsten carbide or diamond is more preferable, and zirconia, alumina, tungsten carbide or diamond is particularly preferable. The Mohs hardness 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 a lump. Examples of the core substance include a particulate lump, an agglomerate in which a plurality of fine particles are aggregated, and an irregular lump.

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

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

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

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

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

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

  Examples of a method for disposing an insulating material on the outer surface of the conductive layer include a chemical method and a physical or mechanical method. Examples of the chemical method include an interfacial polymerization method, a suspension polymerization method in the presence of particles, and an emulsion polymerization method. Examples of the physical or mechanical method include spray drying, hybridization, electrostatic adhesion, spraying, dipping, and vacuum deposition. In particular, since the insulating substance is difficult to be detached, a method of disposing the insulating substance on the surface of the conductive layer through a chemical bond is preferable.

  The outer surface of the conductive layer (the gold layer) and the surface of the insulating particles may each be coated with a compound having a reactive functional group. The outer surface of the conductive layer and the surface of the insulating particles 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 into 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 polyethyleneimine.

  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 average diameter of the insulating material is not less than the above lower limit, the conductive layers of the plurality of conductive particles are difficult to contact when the conductive particles are dispersed in the binder resin. When the average diameter of the insulating particles is not more than the above upper limit, it is not necessary to make the pressure too high in order to eliminate the insulating material between the electrodes and the conductive particles when the electrodes are connected. There is no need for heating.

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

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

  From the viewpoint of further improving the conduction reliability, the outer surface of the gold layer is preferably subjected to a rust prevention treatment with a compound having an alkyl group having 6 to 22 carbon atoms. The surface of the gold layer may be antirust treated with a compound containing no phosphorus, or may be antirust treated with a compound having an alkyl group having 6 to 22 carbon atoms and containing no phosphorus.

  From the viewpoint of further improving the conduction reliability, the outer surface of the gold layer is preferably rust-proofed with an alkyl phosphate compound, an alkyl silane camping compound or an alkyl thiol. By the rust prevention treatment, a rust prevention film can be formed on the outer surface of the gold layer.

  The rust preventive film is preferably formed of a compound having an alkyl group having 6 to 22 carbon atoms (hereinafter also referred to as compound A). The outer surface of the gold layer is preferably surface-treated with the compound A. When the number of carbon atoms of the alkyl group is 6 or more, rust is less likely to occur in the entire conductive layer, and in particular, rust is more unlikely to occur in the nickel layer. When the carbon number of the alkyl group is 22 or less, the conductivity of the conductive particles is increased. From the viewpoint of further improving the conductivity of the conductive particles, the alkyl group in the compound A preferably has 16 or less carbon atoms. The alkyl group may have a linear structure or a branched structure. The alkyl group preferably has a linear structure.

  The compound A is not particularly limited as long as it has an alkyl group having 6 to 22 carbon atoms. The compound A has a phosphate 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 preferably at least one selected from the group consisting of alkoxysilanes, alkylthiols having an alkyl group having 6 to 22 carbon atoms, and dialkyl disulfides having an alkyl group having 6 to 22 carbon atoms. 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 phosphate esters or salts thereof, phosphite esters or salts thereof, alkoxysilanes, alkylthiols, and dialkyl disulfides. It is preferable that By using these preferable compounds A, it is possible to further prevent rust from being generated in the conductive layer. From the viewpoint of making rust even more difficult to generate, the compound A is preferably the phosphate ester or salt thereof, phosphite ester or salt thereof, or alkylthiol, and the phosphate ester or salt thereof, Or it is more preferable that it is a phosphite ester or its salt. As for the said compound A, only 1 type may be used and 2 or more types may be used together.

  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 substance. The rust preventive film is preferably chemically bonded to the gold layer. The rust preventive film is preferably chemically bonded to the insulating substance. More preferably, the rust preventive film is chemically bonded to both the gold layer and the insulating material. Due to the presence of the reactive functional group and due to the chemical bond, the rust preventive film is less likely to be peeled off. As a result, rust is less likely to occur on the gold layer, and the insulating material is exposed from the surface of the conductive particles. It becomes more difficult to detach unintentionally.

  Examples of the phosphoric acid ester having an alkyl group having 6 to 22 carbon atoms or a salt thereof include, for example, phosphoric acid hexyl ester, phosphoric acid heptyl ester, phosphoric acid monooctyl ester, phosphoric acid monononyl ester, phosphoric acid monodecyl ester, Monoundecyl phosphate, monododecyl phosphate, monotridecyl phosphate, monotetradecyl phosphate, monopentadecyl phosphate, monohexyl phosphate monosodium salt, monoheptyl phosphate monosodium Salts, monooctyl phosphate monosodium salt, monononyl phosphate monosodium salt, monodecyl phosphate monosodium salt, monoundecyl phosphate monosodium salt, monododecyl phosphate 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 phosphate ester.

  Examples of the phosphite ester having an alkyl group having 6 to 22 carbon atoms or a salt thereof include, for example, hexyl phosphite ester, heptyl phosphite ester, monooctyl phosphite ester, monononyl phosphite ester, Phosphoric acid monodecyl ester, phosphorous acid monoundecyl ester, phosphorous acid monododecyl ester, phosphorous acid monotridecyl ester, phosphorous acid monotetradecyl ester, phosphorous acid monopentadecyl ester, phosphorous acid monohexyl 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 monoun 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.

  Examples of the alkoxysilane having an alkyl group having 6 to 22 carbon atoms include hexyltrimethoxysilane, hexyltriethoxysilane, heptyltrimethoxysilane, heptyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, and nonyltri. Methoxysilane, nonyltriethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, undecyltrimethoxysilane, undecyltriethoxysilane, dodecyltrimethoxysilane, dodecyltriethoxysilane, tridecyltrimethoxysilane, tridecyltriethoxy Examples include silane, tetradecyltrimethoxysilane, tetradecyltriethoxysilane, pentadecyltrimethoxysilane, and pentadecyltriethoxysilane.

  Examples of the alkyl thiol having an alkyl group having 6 to 22 carbon atoms include hexyl thiol, heptyl thiol, octyl thiol, nonyl thiol, decyl thiol, undecyl thiol, dodecyl thiol, tridecyl thiol, tetradecyl thiol, pentadecyl. Examples include thiol and hexadecyl thiol. 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, ditetradecyl disulfide. Examples include decyl disulfide, dipentadecyl disulfide, and dihexadecyl disulfide.

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

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

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

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

  In addition to the conductive particles and the binder resin, the conductive material includes, for example, a filler, an extender, a softener, a plasticizer, a polymerization catalyst, a curing catalyst, a colorant, an antioxidant, a heat stabilizer, and a light stabilizer. Various additives such as an agent, an ultraviolet absorber, a lubricant, an antistatic agent and a flame retardant may be contained.

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

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

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

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

  The connection structure includes a first connection target member, a second connection target member, and a connection portion connecting the first and second connection target members, and the connection portion has the above-described conductivity. The connection structure is preferably formed of particles or formed of a conductive material containing the above-described conductive particles and a binder resin. In the case where conductive particles are used, the connection portion itself is conductive particles. That is, the first and second connection target members are connected by the conductive particles.

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

  A 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 particles 1. In FIG. 3, the conductive particles 1 are schematically shown for 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 52a on the surface (upper surface). The second connection target member 53 has a plurality of second electrodes 53a on the surface (lower surface). The first electrode 52 a and the second electrode 53 a are electrically connected by one or a plurality of conductive particles 1. Therefore, the first and second connection target members 52 and 53 are electrically connected by the conductive particles 1.

The manufacturing method of the connection structure is not particularly limited. As an example of the manufacturing method of the connection structure, the conductive material is disposed between the first connection target member and the second connection target member to obtain a laminate, and then the laminate is heated and pressurized. Methods and the like. The pressure of the pressurization is about 9.8 × 10 ^{4 to} 4.9 × 10 ⁶ Pa. The temperature of the said heating is about 120-220 degreeC.

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

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

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

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

In order to carry out a rust prevention treatment, the following rust preventives (compounds) were used.
Rust preventive agent A: 2-ethylhexyl azide phosphate Rust preventive agent B: Lauryl azide phosphate Rust preventive agent C: Stearyl azide phosphate Rust preventive agent D: Top rinse (Okuno Pharmaceutical Co., Ltd.)

Example 1
(1) Formation of nickel layer In 100 parts by weight of an alkaline solution containing 5% by weight of a palladium catalyst solution, 10 parts by weight of the base particle A is dispersed using an ultrasonic disperser, and then the solution is filtered. The base particle A was taken out. Next, the resin particles were added to 100 parts by weight of a 1% by weight dimethylamine borane solution to activate the surface of the substrate particles A. The substrate particles A whose surfaces were activated were sufficiently washed with water, and then added to 500 parts by weight of distilled water and dispersed to obtain a suspension.

  Further, 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 nickel plating solution was gradually dropped into the suspension to perform electroless nickel plating. Thereafter, the suspension was filtered to take out the particles, washed with water, and dried to obtain particles having a nickel-phosphorus conductive layer (thickness: 0.1 μm) 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 Electroless gold plating treatment was performed to obtain particles in which a gold layer (thickness 9 nm) was disposed on the outer surface of the nickel layer.

(3) Rust prevention treatment By using the above rust preventive agent A, particles were dispersed to obtain conductive particles whose outer surface of the gold layer was subjected to a rust prevention treatment.

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

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

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

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

(Example 6)
(1) Formation of nickel layer In 100 parts by weight of an alkaline solution containing 5% by weight of a palladium catalyst solution, 10 parts by weight of the base particle A is dispersed using an ultrasonic disperser, and then the solution is filtered. The base particle A was taken out. Subsequently, the base particle A was added to 100 parts by weight of a 1% by weight dimethylamine borane solution to activate the surface of the base particle A. The substrate particles A whose surfaces were activated were sufficiently washed with water, and then added to 500 parts by weight of distilled water and dispersed to obtain a suspension.

  Also prepared is 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. did.

  While stirring the obtained suspension at 60 ° C., the nickel plating solution was gradually added dropwise to the suspension to perform electroless nickel plating. Subsequently, a nickel plating solution (pH 10.0) containing nickel sulfate 0.25 mol / L, sodium hypophosphite 0.25 mol / L, sodium citrate 0.15 mol / L and sodium tungstate 0.12 mol / L. The solution was gradually dropped into the suspension, and electroless nickel plating was performed. Thereafter, the suspension was filtered to take out the particles, washed with water, and dried to obtain particles having a nickel-tungsten-phosphorus conductive layer (thickness 0.1 μm) disposed on the surface of the base 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 Electroless gold plating treatment was performed to obtain particles in which a gold layer (thickness 9 nm) was disposed on the outer surface of the nickel layer.

(3) Rust prevention treatment By using the above rust preventive agent A, particles were dispersed to obtain conductive particles whose outer surface of the gold layer was subjected to a rust prevention 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-catalyzed solution containing 8% by weight of a palladium catalyst and stirred. Then, it filtered and wash | cleaned. The base material particle A was added to a 0.5 wt% dimethylamine borane solution having a pH of 6 to obtain base material particles A to which palladium was attached.

  The base particle A to which palladium was adhered was stirred and dispersed in 300 mL of ion exchange water for 3 minutes to obtain a dispersion. Next, 1 g of metallic nickel particle slurry (average particle size 100 nm) was added to the dispersion over 3 minutes to obtain substrate particles A to which a core substance was adhered.

  Using the base particle A to which the core substance is attached, the nickel layer and the gold layer are formed, and the nickel content in the conductive layer 100% by weight is 97.8% by weight, and the phosphorus content is 2. Conductive particles were obtained in the same manner as in Example 1 except that the content was changed to 2% by weight.

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

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

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

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

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

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

(Comparative Example 1)
The pH 9.0 of the nickel plating solution was changed to pH 7.0, thereby changing the nickel content in the conductive layer 100% by weight to 92.5% by weight and the phosphorus content to 7.5% by weight. Except that, conductive particles were obtained in the same manner as in Example 1.

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

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

(Example 10)
Except having changed the rust preventive agent A into the rust preventive agent D, it carried out similarly to Example 1, and obtained electroconductive particle.

(Example 11)
Implemented except that the base particle A was changed to the base particle C, and the nickel content in the conductive layer 100 wt% was changed to 97.5 wt% and the phosphorus content was changed to 2.5 wt%. In the same manner as in Example 1, conductive particles were obtained.

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

(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 silicone alkoxy oligomer (“X-41-1053” manufactured by Shin-Etsu Chemical Co., Ltd.) in an aqueous ammonia solution in the reaction vessel. The mixture with was added slowly. After the hydrolysis and condensation reaction proceeded with stirring, 2.4 mL of a 25 wt% aqueous ammonia solution was added, and then the particles were isolated from the aqueous ammonia solution, and the resulting particles were subjected to an oxygen partial pressure of 10 ⁻¹⁷ atm. And calcination at 350 ° C. for 2 hours to obtain organic-inorganic hybrid particles having a particle size of 3.0 μm. Other than using the obtained organic hybrid particles as the base particle E, and changing the nickel content in the conductive layer 100% by weight to 97.7% by weight and the phosphorus content to 2.3% by weight. Were obtained in the same manner as in Example 1 to obtain conductive particles.

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

  Moreover, the plating solution for protrusion formation containing sodium hypophosphite 0.25 mol / L and sodium hydroxide 0.05 mol / L was prepared.

  An electroless plating treatment was performed using the base particle A and the electroless nickel plating solution. Next, in order to form protrusions on the conductive layer, a protrusion-forming plating solution was gradually dropped to form protrusions. Nickel plating was performed while dispersing Ni protrusion nuclei generated in the plating solution by ultrasonic stirring. By performing the electroless plating process using the latter electroless nickel plating solution, particles having a nickel layer (nickel-phosphorus alloy layer, thickness 80 nm) and precipitation protrusions 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 sodium hypophosphite 0.75 mol / L was prepared.

  Moreover, the plating solution for protrusion formation containing sodium hypophosphite 0.25 mol / L and sodium hydroxide 0.05 mol / L was prepared.

  An electroless plating treatment was performed using the base particle A and the electroless nickel plating solution. Next, in order to form protrusions on the conductive layer, a protrusion-forming plating solution was gradually dropped to form protrusions. Nickel plating was performed while dispersing Ni protrusion nuclei generated in the plating solution by ultrasonic stirring. By performing the electroless plating process using the latter electroless nickel plating solution, particles having a nickel layer (nickel-phosphorus alloy layer, thickness 80 nm) and precipitation protrusions 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 forming the nickel layer, 0.10 mol / L of sodium tungstate was added to the nickel plating solution, whereby the nickel content in the conductive layer 100% by weight was 97.1% by weight and the phosphorus content was 1. Particles with a nickel layer (nickel-phosphorus-tungsten alloy layer, thickness 80 nm) were obtained in the same manner as in Example 1 except that the content was changed to 9 wt% and the tungsten content was 1.0 wt%.

  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 prepared using a focused ion beam. Using a transmission electron microscope FE-TEM (“JEM-2010FEF” manufactured by JEOL Ltd.), each content of nickel, phosphorus and tungsten in the conductive layer was measured by an energy dispersive X-ray analyzer (EDS). The content in the entire nickel layer was determined.

(2) Initial connection resistance The obtained conductive particles were added to “Strectbond XN-5A” manufactured by Mitsui Chemicals Co., Ltd. so as to have a content of 10% by weight. Produced.

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

  On the said transparent glass substrate, the anisotropic conductive paste immediately after preparation was applied so that it might become thickness of 30 micrometers, and the anisotropic conductive paste layer was formed. Next, the semiconductor chip was stacked on the anisotropic conductive paste layer so that the electrodes face each other. Then, while adjusting the temperature of the head so that the temperature of the anisotropic conductive paste layer becomes 185 ° C., a pressure heating head is placed on the upper surface of the semiconductor chip and a pressure of 1 MPa is applied to form the anisotropic conductive paste layer. It hardened | cured at 185 degreeC and the connection structure was obtained.

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

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

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

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

  The results are shown in Table 1 below.

  In the evaluation of the connection resistance after the (3) reliability test, the obtained connection structure was left under conditions of 85 ° C. and relative humidity of 85%. Even after obtaining the connection structure after leaving the conductive particles before obtaining the connection structure under the conditions of 85 ° C. and 85% relative humidity, the above-mentioned (3) after the reliability test The same tendency as the evaluation result of the connection resistance was observed. Further, in Examples 14 and 15, the surface area of the portion having the protrusion was 30% or more out of 100% of the total surface area of the outer surface of the gold layer.

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 substance 25 ... Insulating substance 51 ... Connection structure 52 ... 1st connection object member 52a ... 1st electrode 53 ... 2nd connection object member 53a ... 2nd electrode 54 ... Connection part

Claims (12)

Substrate particles,
A nickel layer disposed on the surface of the substrate particles and containing nickel and phosphorus;
A gold layer disposed on the outer surface of the nickel layer and comprising gold,
In the total 100% by weight of the nickel layer, the phosphorus content is less than 5% by weight,
The gold layer has a thickness of less than 15 nm;
Conductive particles in which the outer surface of the gold layer is rust-proofed.   The electroconductive particle of Claim 1 whose thickness of the said gold layer is 10 nm or less.   The electroconductive particle of Claim 1 or 2 by which the outer surface of the said gold layer is rust-proofed with the compound which has a C6-C22 alkyl group.   The conductivity according to any one of claims 1 to 3, wherein phosphorus is unevenly distributed in the thickness direction of the nickel layer 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 by which the outer surface of the said gold layer is rust-proofed with the compound which does not contain phosphorus.   The electroconductive particle of any one of Claims 1-5 which has a some protrusion on the outer surface of the said gold layer.   The conductive particle according to claim 6, further comprising a plurality of core materials that bulge the outer surface of the gold layer so as to form a plurality of the protrusions.   The electroconductive particle of Claim 7 whose Mohs hardness of the material of the said core substance is 5 or more.   The electroconductive particle of any one of Claims 6-8 whose surface area of the part with the said protrusion is 30% or more in 100% of the total surface area of the outer surface of the said gold layer.   The electroconductive particle of any one of Claims 1-9 provided with the insulating substance arrange | positioned on the outer surface of the said gold layer.   The electroconductive material containing the electroconductive particle of any one of Claims 1-10, and binder resin. A first connection object member having a first electrode on its surface;
A second connection target member having a second electrode on its surface;
A connection portion connecting the first connection target member and the second connection target member;
The connecting portion is formed of the conductive particles according to any one of claims 1 to 10, or is formed of a conductive material including the conductive particles and a binder resin.
A connection structure in which the first electrode and the second electrode are electrically connected by the conductive particles.

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