JP6734055B2 - Conductive particles, conductive material and connection structure - Google Patents

Description

The present invention relates to a conductive particle having a base particle and a conductive portion arranged on the outer surface of the base particle. The present invention also relates to a conductive material and a connection structure using the above 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 the binder resin.

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

As an example of the conductive particles, in Patent Document 1 below, a coating step of forming a conductive metal layer containing nickel on the surface of the resin particles to produce metal-coated particles, and the metal-coated particles, Disclosed is a conductive particle obtained by a heat treatment step of performing heat treatment at a temperature of 180° C. to 350° C. in a non-oxidizing atmosphere.

Moreover, the following Patent Document 2 discloses conductive particles having base particles and a conductive metal layer coating the outer surface of the base particles. The conductive metal layer includes a nickel plating layer. When the cross section in the thickness direction is observed using a scanning electron microscope at a magnification of 100,000, the nickel plating layer has grain boundaries in the cross section, and the grain boundary structure has a thickness of the nickel plating layer. The layer does not have a columnar structure and is oriented in the vertical direction.

Further, Patent Document 3 below discloses conductive particles composed of base particles and at least one conductive metal layer coating the outer surface of the base particles. The conductive metal layer includes a layer formed of nickel or a nickel alloy. The ratio of the average thickness and the average grain boundary width of the layer formed of nickel or nickel alloy (average thickness/average grain boundary width) is 0.1 or more and less than 5.

JP, 2013-008474, A JP, 2013-073694, A JP, 2014-011117, A

When the electrodes of the semiconductor chip and the electrodes of the glass substrate are electrically connected by the anisotropic conductive material, for example, the anisotropic conductive material containing conductive particles is arranged on the glass substrate. Next, the semiconductor chips are stacked and heated and pressed. As a result, the anisotropic conductive material is cured and the electrodes are electrically connected via the conductive particles to obtain a connection structure.

In the conventional conductive particles as described in Patent Documents 1 to 3, after the connection between the electrodes, the action of the compressed conductive particles trying to return to the original shape works, and a phenomenon called springback occurs. There is. For this reason, the contact between the electrodes and the conductive particles may be lowered, or the conductive layer may be cracked, resulting in poor conduction. That is, the connection structure using the conventional conductive particles may have low conduction reliability.

It is an object of the present invention to provide conductive particles that can improve conduction reliability when electrodes are electrically connected. Moreover, the objective of this invention is providing the electrically-conductive material and connection structure which used the said electrically-conductive particle.

According to a broad aspect of the present invention, a base particle, on the outer surface of the base particle, comprising a conductive portion arranged so as to contact the base particle, there is a hole in the conductive portion, The thickness of the conductive portion is 50 nm or more, and in the first region having a thickness of 40 nm from the inner surface of the conductive portion toward the outer side in the thickness direction of the conductive portion, the diameter is 1 nm or more and 20 nm or less per 1 μm ^2. Provided is a conductive particle having 50 or less holes.

In a specific aspect of the conductive particle according to the present invention, a plurality of holes are present in the conductive portion, and in the first region, two or more holes having a diameter of 1 nm or more and 20 nm or less per 1 μm ^2. Exists in.

In a specific aspect of the conductive particle according to the present invention, 50 μm or less of pores having a diameter of 1 nm or more and 20 nm or less exist in 1 μm ² in the conductive part.

In a specific aspect of the conductive particle according to the present invention, there is no hole having a diameter of 1 nm or more and 20 nm or less in the second region except the first region of the conductive portion, or 1 μm ² Therefore, there are less than 20 holes having a diameter of 1 nm or more and 20 nm or less.

On the specific situation with the electroconductive particle which concerns on this invention, the said electroconductive part contains nickel.

On the specific situation with the electroconductive particle which concerns on this invention, the particle diameter of the said base material particle is 1 micrometer or more and 5 micrometers or less.

In one specific aspect of the conductive particles according to the present invention, the base particles are resin particles or organic-inorganic hybrid particles, and in another particular aspect, the base particles are resin particles.

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

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

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

According to a broad aspect of the present invention, a first connection target member having a first electrode on a surface, a second connection target member having a second electrode on a surface, the first connection target member, and A connecting part connecting the second connection target member, wherein the material of the connecting part is the conductive particles described above, or 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 include a base particle and a conductive portion arranged on the outer surface of the base particle so as to be in contact with the base particle, and a hole exists in the conductive portion. In the first region having a thickness of 50 nm or more and a thickness of 40 nm from the inner surface of the conductive portion toward the outer side in the thickness direction of the conductive portion, the diameter is 1 nm or more and 20 nm or less per 1 μm ^2. Since there are 50 or less holes, the conduction reliability can be improved when the electrodes are electrically connected.

FIG. 1 is a cross-sectional view showing conductive particles according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view showing conductive particles according to the second embodiment of the present invention. FIG. 3 is a cross-sectional view showing conductive particles according to the third embodiment of the present invention. FIG. 4 is a sectional view schematically showing a connection structure using conductive particles according to the first embodiment of the present invention. FIG. 5 shows, in a conductive part including a hole, a first region having a thickness of 40 nm from the inner surface of the conductive part toward the outer side in the thickness direction of the conductive part, and a second region excluding the first region of the conductive part. It is a schematic diagram for explaining.

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

(Conductive particles)
The conductive particles according to the present invention include base particles and conductive parts. In the conductive particle according to the present invention, the conductive portion is arranged on the outer surface of the base material particle so as to be in contact with the base material particle. In the conductive particle according to the present invention, holes are present in the conductive part. In the conductive particle according to the present invention, the conductive portion has a thickness of 50 nm or more. In the conductive particles according to the present invention, pores having a diameter of 1 nm or more and 20 nm or less per 1 μm ² in the first region having a thickness of 40 nm from the inner surface of the conductive portion toward the outer side in the thickness direction of the conductive portion. There are 50 or less. The above diameter means the maximum diameter.

The holes having a diameter of 1 nm or more and 20 nm or less do not include a hole having a diameter of less than 1 nm and a hole having a diameter of more than 20 nm. Whether or not the hole exists in the first region is determined by whether or not the central portion of the hole exists in the first region. The holes are observed in the cross section, and the diameter means the maximum diameter appearing in the cross section.

With the above-described configuration of the present invention, when the electrodes are electrically connected using the conductive particles of the present invention, the connection resistance can be lowered and the conduction reliability can be improved. After the connection between the electrodes, the action of the compressed conductive particles to return to the original shape is large and difficult to work. This is because the conductive portion portion including the hole (particularly the first area) serves as a cushion layer, and the conductive portion portion including the hole (particularly the first area) reduces elastic strain accumulated in the conductive portion. It is thought to be for alleviation. With the conductive particles according to the present invention, when the compressed conductive particles try to return to their original shape, cracking of the conductive portion is unlikely to occur. Further, since the action of the compressed conductive particles to return to the original shape is hard to work, the contact between the electrodes and the conductive particles can be sufficiently secured. In the present invention, even if the conductive particles are exposed to high temperature or high humidity, the increase in connection resistance can be suppressed. In particular, it is possible to suppress an increase in connection resistance under high humidity.

From the viewpoint of suppressing springback and increasing conduction reliability, holes having a diameter of 1 nm or more and 20 nm or less are formed in the first region having a thickness of 40 nm from the inner surface of the conductive portion toward the outer side in the thickness direction of the conductive portion. Exists.

From the viewpoint of suppressing springback and further improving conduction reliability, the number of holes having a diameter of 1 nm or more and 20 nm or less per 1 μm ² in the first region is preferably 2 or more, and more preferably 5 or more. Is. From the viewpoint of suppressing springback and further improving conduction reliability, the number of holes having a diameter of 1 nm or more and 20 nm or less per 1 μm ² is preferably 45 or less in the first region.

From the viewpoint of suppressing cracking of the conductive portion and further enhancing the conduction reliability, is there a hole having a diameter of 1 nm or more and 20 nm or less in the second region of the conductive portion excluding the first region? Or, it is preferable that there are less than 20 pores having a diameter of 1 nm or more and 20 nm or less per 1 μm ² . From the viewpoint of suppressing the cracking of the conductive portion and further improving the conduction reliability, the smaller the number of holes in the second region, the better. In the second region, the number of pores having a diameter of 1 nm or more and 20 nm or less per 1 μm ² is preferably 10 or less.

Whether or not the hole exists in the second region is determined by whether or not the central portion of the hole exists in the second region. The holes are observed in the cross section, and the diameter means the maximum diameter appearing in the cross section.

From the viewpoint of suppressing springback and further improving conduction reliability, the number of holes having a diameter of 1 nm or more and 20 nm or less per 1 μm ² in the conductive portion is preferably 2 or more, and more preferably 5 or more. .. From the viewpoint of suppressing springback and further enhancing conduction reliability, the number of holes having a diameter of 1 nm or more and 20 nm or less per 1 μm ² in the conductive portion is preferably 50 or less, more preferably 45 or less. ..

From the viewpoint of suppressing cracking of the conductive portion and further improving the conduction reliability, the number of holes having a diameter of 1 nm or more and 20 nm or less per 1 μm ² in the first region is 1 μm in the second region. The number of holes having a diameter of 1 nm or more and 20 nm or less per ² is preferably larger, more preferably 5 or more, and further preferably 10 or more.

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. Further, the respective configurations in the respective embodiments shown below can be combined appropriately.

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

The conductive particle 1 shown in FIG. 1 has a base particle 2 and a conductive portion 3 arranged on the surface of the base particle 2. The conductive portion 3 is in contact with the surface of the base particle 2 and covers the surface of the base particle 2. The conductive particle 1 is a coated particle in which the surface of the base material particle 2 is coated with the conductive portion 3.

There are a plurality of holes 3a in the conductive portion 3. The thickness of the conductive portion 3 is 50 nm or more.

In the conductive portion 3, there is a hole having a diameter of 1 nm or more and 20 nm or less among the holes 3a. In the first region R1 having a thickness of 40 nm from the inner surface of the conductive portion 3 toward the outer side in the thickness direction of the conductive portion 3, there is a hole having a diameter of 1 nm or more and 20 nm or less among the holes 3a, and the diameter is specific. There are holes within the range within the above number range.

In the conductive portion 3 having the holes 3a, a first region R1 having a thickness of 40 nm from the inner surface of the conductive portion 3 toward the outer side in the thickness direction of the conductive portion 3 and the first region R1 of the conductive portion 3 are shown in FIG. The removed second region R2 is illustrated. The thickness of the conductive portion 3 from the inner surface of the conductive portion 3 to the broken line L is 40 nm. Further, the conductive portion portion inside the broken line L is the first region R1. The conductive portion outside the broken line L is the second region R2.

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

The conductive particles 1A shown in FIG. 2 are arranged on the base particle 2, the conductive portion 3 (first conductive portion) arranged on the surface of the base particle 2, and the outer surface of the conductive portion 3. It has a second conductive portion 4. The base particle 2 and the conductive portion 3 of the conductive particle 1A are the same as the base particle 2 and the conductive portion 3 of the conductive particle 1. The second conductive portion 4 is in contact with the conductive portion 3. In the conductive particles 1A, a multilayer conductive portion is formed.

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

The conductive particle 1B shown in FIG. 3 includes a base material particle 2, a conductive portion 3B, a plurality of core substances 5, and a plurality of insulating substances 6. The base particle 2 in the conductive particle 1B is the same as the base particle 2 in the conductive particle 1. There are a plurality of holes 3Ba in the conductive portion 3B. The thickness of the conductive portion 3B is 50 nm or more.

In the first region R1 having a thickness of 40 nm from the inner surface of the conductive portion 3B toward the outer side in the thickness direction of the conductive portion 3B, holes having a diameter of 1 nm or more and 20 nm or less of the holes 3Ba per 1 μm ² (the diameter is specific Pore within the range) exists within the above range.

The conductive portion 3B of the conductive particle 1B differs from the conductive portion 3 of the conductive particle 1 in the presence or absence of a protrusion.

The conductive particle 1B has a plurality of protrusions 1Ba on its outer surface. The conductive portion 3B has a plurality of protrusions 3Bb on the outer surface. As described above, the conductive particles may have protrusions on the outer surface of the conductive particles, and the conductive portion may have protrusions on the outer surface. A plurality of core substances 5 are arranged on the surface of the base material particles 2. The plurality of core substances 5 are embedded in the conductive portion 3B. The core substance 5 is arranged inside the protrusions 1Ba and 3Bb. The conductive portion 3B covers a plurality of core substances 5. The outer surface of the conductive portion 3B is raised by the plurality of core substances 5, and the protrusions 1Ba and 3Bb are formed. The core substance is preferably arranged inside or inside the conductive portion. The core substance does not necessarily have to be used to form the protrusion.

The conductive particles 1B have the insulating substance 6 arranged on the outer surface of the conductive portion 3B. At least a part of the outer surface of the conductive portion 3B is covered with the insulating material 6. The insulating substance 6 is made of a material having an insulating property and is an insulating particle. In this way, the conductive particles may have an insulating substance arranged on the outer surface of the conductive portion.

The details of the conductive particles will be described below. In the following description, “(meth)acrylic” means one or both of “acrylic” and “methacrylic”, and “(meth)acrylate” means one or both of “acrylate” and “methacrylate”. To do.

[Base material particles]
Examples of the base particles include resin particles, inorganic particles other than metal particles, organic-inorganic hybrid particles, and metal particles. The base particles are preferably base 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.

From the viewpoint of effectively increasing the conduction reliability, the base particles on which the specific conductive portion is formed are preferably resin particles or organic-inorganic hybrid particles, and more preferably resin particles. Further, when the base particles are resin particles or organic-inorganic hybrid particles, particularly when the base particles are resin particles, the conductive particles are easily deformed during the pressure bonding, and the conductive particles and the electrode come into contact with each other. The area becomes large. Therefore, the connection resistance between the electrodes is further reduced.

Various organic substances are preferably 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 Oxides, polyacetals, polyimides, polyamideimides, polyetheretherketones, polyethersulfones, and polymers obtained by polymerizing one or more kinds of various polymerizable monomers having an ethylenically unsaturated group Can be mentioned. Resin particles for forming the resin particles can be designed and synthesized, and resin particles having arbitrary physical properties at the time of compression suitable for the conductive material can be easily controlled in a suitable range. 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 polymerizable monomer having an ethylenically unsaturated group, the polymerizable monomer having the ethylenically unsaturated group is a non-crosslinkable monomer. And a crosslinkable monomer.

Examples of the non-crosslinkable monomer include styrene-based monomers such as styrene and α-methylstyrene; carboxyl group-containing monomers such as (meth)acrylic acid, maleic acid, and maleic anhydride; methyl ( (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 atoms such as 2-hydroxyethyl (meth)acrylate, glycerol (meth)acrylate, polyoxyethylene (meth)acrylate and glycidyl (meth)acrylate Contained (meth)acrylates; Nitrile-containing monomers such as (meth)acrylonitrile; Vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether; Acid vinyl esters such as vinyl acetate, vinyl butyrate, vinyl laurate, vinyl stearate Unsaturated hydrocarbons such as ethylene, propylene, isoprene and butadiene; halogen-containing monomers such as trifluoromethyl (meth)acrylate, pentafluoroethyl (meth)acrylate, vinyl chloride, vinyl fluoride and chlorostyrene Can be mentioned.

Examples of the crosslinkable monomer include tetramethylolmethane tetra(meth)acrylate, tetramethylolmethane tri(meth)acrylate, tetramethylolmethane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, 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 and 1,4-butanediol di(meth)acrylate; triallyl(iso)cyanurate, triallyl trimellitate, divinylbenzene, Examples thereof include silane-containing monomers such as diallyl phthalate, diallyl acrylamide, diallyl ether, γ-(meth)acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, and vinyltrimethoxysilane.

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

When the base particles are inorganic particles excluding metal particles or organic-inorganic hybrid particles, examples of the inorganic material for forming the base particles include silica, alumina, barium titanate, zirconia and carbon black. .. It is preferable that the inorganic substance is not a metal. The particles formed of the above silica are not particularly limited, but for example, after hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups to form crosslinked polymer particles, firing is optionally performed. Particles obtained by carrying out are included. 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 arranged 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 lowering the connection resistance between the electrodes, the base material particles are preferably organic-inorganic hybrid particles having an organic core and an inorganic shell arranged 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 the inorganic materials for forming the base particles described above. 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 silane alkoxide. The inorganic shell is preferably made of silane alkoxide.

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

The particle diameter of the base particles is preferably 0.1 μm or more, more preferably 0.5 μm or more, still more preferably 1 μm or more, preferably 100 μm or less, more preferably 20 μm or less, still more preferably 5 μm or less. .. It is particularly preferably 3 μm or less. When the particle size of the base material particles is equal to or more than the above lower limit and equal to or less than the above upper limit, small conductive particles can be obtained even if the distance between the electrodes is small and the thickness of the conductive portion is increased.

Since it is possible to obtain smaller conductive particles and to ensure high conduction reliability even when the conductive portion has a small thickness due to the configuration of the present invention, the particle diameter of the base material particles is preferably 0. It is 1 μm or more, and preferably 5 μm or less.

The particle size of the base particles indicates the diameter when the base particles are spherical, and indicates the maximum diameter when the base particles are not spherical.

[Conductive part]
The conductive particles include a conductive portion (conductive layer) including holes. A second conductive portion may be formed on the outer surface of the conductive portion (conductive layer) including the holes as a conductive portion (conductive layer) different from the conductive portion including the holes.

The metal for forming the conductive portion is not particularly limited. Examples of the metal include gold, silver, palladium, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, thallium, germanium, cadmium, silicon and these. Alloys and the like. Further, examples of the metal include tin-doped indium oxide (ITO) and solder. These metals may be used alone or in combination of two or more. An alloy containing tin, nickel, palladium, copper or gold is preferable, nickel or palladium is more preferable, and nickel is particularly preferable, because the connection resistance between the electrodes can be further reduced.

It is preferable that the conductive portion having a hole contains nickel as a main metal. The content of nickel is preferably 50% by weight or more based on 100% by weight of the entire conductive portion having holes. The content of nickel is preferably 65% by weight or more, more preferably 80% by weight or more, still more preferably 90% by weight or more based on 100% by weight of the entire conductive portion having holes. When the content of nickel is at least the above lower limit, the conductivity reliability is further enhanced.

When the conductive portion is formed of a plurality of layers, the outermost layer is preferably a gold layer, a nickel layer, a palladium layer, a copper layer or an alloy layer containing tin and silver, and is a gold layer. Is more preferable. When the outermost layer is these preferable conductive parts, the connection resistance between the electrodes becomes even lower. Moreover, when the outermost layer is a gold layer, the corrosion resistance is further enhanced.

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

In addition, as a method for allowing the holes to exist in the conductive portion, there are a first method in which H ₂ bubbles are taken into the conductive portion such as a plating film and a second method in which an organic substance is codeposited in the plating film. In particular, the first method of incorporating H ₂ bubbles into the conductive portion such as the plated film is preferable. The first method is to increase the liquid specific gravity of the plating solution so that the bubbles of H ₂ generated in the plating reaction are hard to escape from the plating solution, and the bubbles of H ₂ retained in the plating solution are the base particles. Alternatively, a method of trapping in the plating film during the growth process and incorporating it into the plating film by growth of the plating film can be mentioned. Examples of the method for measuring the liquid specific gravity of the plating solution include a method for measuring the Baume degree using a Baume specific gravity meter. The Baume degree is preferably 8 or more, more preferably 10 or more. Examples of the method for increasing the liquid specific gravity of the plating solution include a method for increasing the contents of organic substances and metal ions in the plating solution.

The particle diameter of the conductive particles is preferably 0.5 μm or more, more preferably 1 μm or more, preferably 500 μm or less, more preferably 100 μm or less, still more preferably 50 μm or less, particularly preferably 20 μm or less. The particle diameter of the conductive particles may be 5 μm or less. When the particle size of the conductive particles is not less than the above lower limit and not more than the above upper limit, when connecting the electrodes using the conductive particles, the contact area between the conductive particles and the electrode becomes sufficiently large, and the conductive portion It becomes difficult for the conductive particles that have aggregated to form when forming. In addition, the distance between the electrodes connected via the conductive particles does not become too large, and the conductive portion is less likely to peel off from the outer surface of the base material particles. Further, when the particle diameter of the conductive particles is not less than the above lower limit and not more than the above upper limit, the conductive particles can be suitably used for the purpose of the conductive material.

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

The thickness of the conductive portion including the holes is 50 nm or more. The thickness of the conductive portion including the holes is preferably 70 nm or more, more preferably 90 nm or more, preferably 200 nm or less, more preferably 180 nm or less, still more preferably 160 nm or less. When the thickness of the conductive portion including pores is not less than the above lower limit and not more than the above upper limit, sufficient conductivity is obtained, and the conductive particles do not become too hard, and the conductive particles are sufficient when connecting between the electrodes. Transforms into.

When the conductive portion is formed of a plurality of layers, the thickness of the second conductive portion and the thickness of the conductive portion of the outermost layer is preferably 50 nm or more, more preferably 70 nm or more, preferably 200 nm or less, More preferably, it is 180 nm or less. When the thickness of the second conductive portion and the conductive portion of the outermost layer is not less than the lower limit and not more than the upper limit, the coating of the conductive portion of the outermost layer is uniform, the corrosion resistance is sufficiently high, and the interelectrode gap is high. Connection resistance is further reduced. Further, when the outermost layer is a gold layer, the thinner the gold layer, the lower the cost.

The thickness of the conductive part can be measured by observing the cross section of the conductive particle using, for example, a transmission electron microscope (TEM).

[Core substance]
The conductive particles preferably have protrusions on the outer surface of the conductive portion. It is preferable that the projections are plural. An oxide film is often formed on the surface of the conductive portion and the surface of the electrode connected by the conductive particles. When the conductive particles having projections are used, the conductive particles are arranged between the electrodes and pressure-bonded, whereby the oxide film is effectively removed by the projections. Therefore, the electrode and the conductive portion of the conductive particle can be more surely brought into contact with each other, and the connection resistance between the electrodes can be reduced. Furthermore, when the conductive particles are provided with an insulating substance on the surface, or when the conductive particles are dispersed in a binder resin to be used as a conductive material, the projection of the conductive particles causes the conductive particles and the electrode to be separated from each other. The insulating material or the binder resin between them can be effectively removed. Therefore, the reliability of conduction between the electrodes can be improved.

As the method for forming the projections, a method of forming a conductive portion by electroless plating after attaching a core substance to the outer surface of the base material particle, and forming a conductive portion by electroless plating on the outer surface of the base material particle After that, a core material is attached and a conductive portion is formed by electroless plating, and a core material is added during electroless plating to form a conductive portion by electroless plating. However, the core substance does not necessarily have to be used in order to form the protrusions on the surfaces of the conductive particles and the conductive portion.

As a method for disposing the core substance, for example, the core substance is added to a dispersion liquid of base particles, etc., and the core substance is accumulated on the outer surface of the base particles by, for example, Van der Waals force, and attached. And a method in which a core substance is added to a container containing base particles and the core substance is attached to the surface of the base particles by a mechanical action such as rotation of the container. Since it is easy to control the amount of the core substance to be adhered, a method of accumulating and adhering the core substance on the surface of the base particles or the like in the dispersion liquid is preferable.

Examples of the substance forming the core substance include a conductive substance and a non-conductive substance. Examples of the conductive substance include metals, metal oxides, conductive non-metals such as graphite, and conductive polymers. Examples of the conductive polymer include polyacetylene. Examples of the non-conductive substance include silica, alumina, barium titanate and zirconia. A metal is preferable because it can increase the conductivity and effectively lower the connection resistance. 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 of the alloy include alloys, tin-copper alloys, tin-silver alloys, tin-lead-silver alloys, and tungsten carbide.

The material of the core substance is not particularly limited. The Mohs hardness of the core material is preferably high.

Specific examples of the material of the core substance 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. (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 are more preferable, and zirconia, alumina, tungsten carbide or diamond are particularly preferable. The Mohs hardness of the material of the core substance is preferably 4 or more, more preferably 5 or more, even more preferably 6 or more, further preferably 7 or more, and particularly preferably 7.5 or more.

The shape of the core substance is not particularly limited. The shape of the core substance is preferably massive. Examples of the core substance include a particulate mass, an agglomerate of a plurality of fine particles, and an amorphous mass.

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 lower limit and not more than the upper limit, the connection resistance between the electrodes is effectively reduced.

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

The number of protrusions (number of protrusions) on the outer surface of the conductive portion per one conductive particle is preferably 3 or more, more preferably 5 or more, more preferably 10 or more, and further preferably 20 or more. .. The upper limit of the number of protrusions is not particularly limited. From the viewpoint of further enhancing the conduction reliability, the number of protrusions on the outer surface of the conductive portion per one conductive particle is preferably 1000 or less, more preferably 500 or less, and further preferably 300 or less. ..

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 equal to or higher than the lower limit and equal to or lower than the upper limit, the connection resistance between the electrodes is effectively reduced.

The height of the protrusion is a virtual line of the conductive portion (the broken line shown in FIG. 3) on the line connecting the center of the conductive particle and the tip of the protrusion (broken line L1 shown in FIG. 3) assuming that there is no protrusion. L2) Shows the distance from the top (on the outer surface of the spherical conductive particle assuming no protrusion) to the tip of the protrusion. That is, in FIG. 3, the distance from the intersection of the broken line L1 and the broken line L2 to the tip of the protrusion is shown.

[Insulating material]
The conductive particles according to the present invention preferably include an insulating substance disposed on the outer surface of the conductive portion. In this case, if conductive particles are used to connect the electrodes, a short circuit between adjacent electrodes can be prevented. Specifically, when a plurality of conductive particles are in contact with each other and an insulating substance is present between the plurality of electrodes, it is possible to prevent a short circuit between laterally adjacent electrodes instead of between the upper and lower electrodes. In addition, when connecting the electrodes, the conductive particles are pressed by the two electrodes, so that the insulating material between the conductive portion of the conductive particles and the electrodes can be easily removed. When the conductive particles have a plurality of protrusions on the outer surface of the conductive portion, the insulating substance between the conductive portion of the conductive particles and the electrode can be easily removed.

The insulating substance is preferably insulating particles because the insulating substance can be more easily removed during pressure bonding between the electrodes.

Specific examples of the insulating resin that is a material of the insulating substance include polyolefins, (meth)acrylate polymers, (meth)acrylate copolymers, block polymers, thermoplastic resins, crosslinked products of thermoplastic resins, and A curable resin, a water-soluble resin, etc. are mentioned.

Examples of the above-mentioned polyolefins include polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester 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, a styrene-acrylic acid ester copolymer, an SB type styrene-butadiene block copolymer, an SBS type styrene-butadiene block copolymer, and hydrogenated products thereof. Examples of the thermoplastic resin include vinyl polymers and vinyl copolymers. Examples of the thermosetting resin include epoxy resin, phenol resin, and melamine resin. Examples of the water-soluble resin include polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyvinylpyrrolidone, polyethylene oxide and methyl cellulose. Water-soluble resins are preferable, and polyvinyl alcohol is more preferable.

The average diameter (average particle diameter) of the insulating substance 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 substance 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 (average particle diameter) of the insulating substance is not less than the above lower limit, it becomes difficult for the conductive portions of the plurality of conductive particles to contact each other when the conductive particles are dispersed in the binder resin. When the average diameter of the insulating particles (average particle diameter) is less than or equal to the above upper limit, the pressure is set too high in order to eliminate the insulating substance between the electrodes and the conductive particles when connecting the electrodes. Eliminates the need for heating to high temperatures.

The “average diameter (average particle diameter)” of the insulating substance means the number average diameter (number average particle diameter). The average diameter of the insulating substance can be obtained by using a particle size distribution measuring device or the like.

[Rust prevention treatment]
In order to suppress the corrosion of the conductive particles and reduce the connection resistance between the electrodes, it is preferable that the outer surface of the conductive portion be rustproofed.

From the viewpoint of further enhancing the conduction reliability, it is preferable that the outer surface of the conductive portion be rustproofed with a compound having an alkyl group having 6 to 22 carbon atoms. From the viewpoint of further enhancing the conduction reliability, it is preferable that the outer surface of the conductive portion be rustproofed with an alkylphosphoric acid compound or an alkylthiol. A rustproof film can be formed on the outer surface of the conductive portion by the rustproof treatment.

(Conductive material)
The conductive material according to the present invention contains 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 between electrodes. The conductive material is preferably a conductive material for circuit connection.

The binder resin is not particularly limited. A known insulating resin is used as the binder resin. The binder resin preferably contains a thermoplastic component (thermoplastic compound) or a curable component, and more preferably contains a curable component. Examples of the curable component include a photocurable component and a thermosetting component. The photocurable component preferably contains a photocurable compound and a photopolymerization initiator. The thermosetting component preferably contains a thermosetting compound and a thermosetting agent.

Examples of the binder resin include vinyl resins, thermoplastic resins, curable resins, thermoplastic block copolymers and elastomers. 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 resin, ethylene-vinyl acetate copolymer, and polyamide resin. Examples of the curable resin include epoxy resin, urethane resin, polyimide resin and unsaturated polyester resin. The curable resin may be a room temperature curable resin, a thermosetting resin, a photocurable resin or a moisture curable resin. The curable resin may be used in combination with a curing agent. Examples of the thermoplastic block copolymer include styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, hydrogenated products of styrene-butadiene-styrene block copolymer, and styrene-isoprene. —Styrene block copolymer hydrogenated products and the like. 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, a filler, a softening agent, a plasticizer, a polymerization catalyst, a curing catalyst, a colorant, an antioxidant, a heat stabilizer, and a light stabilizer. It may contain various additives such as agents, ultraviolet absorbers, lubricants, antistatic agents and flame retardants.

The conductive material according to the present invention can be used as a conductive paste, a conductive film, or the like. When the conductive material according to the present invention is a conductive film, a film containing no 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 in 100% by weight of the conductive material is preferably 10% by weight or more, more preferably 30% by weight or more, further preferably 50% by weight or more, particularly preferably 70% by weight or more, and preferably It is 99.99% by weight or less, more preferably 99.9% by weight or less. When the content of the binder resin is not less than the lower limit and not more than the 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 enhanced.

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 80% by weight or less, more preferably 60% by weight. It is preferably 40% by weight or less, more preferably 20% by weight or less, and most preferably 10% by weight or less. When the content of the conductive particles is equal to or higher than the lower limit and equal to or lower than the upper limit, conduction reliability between the electrodes is further enhanced.

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

The said connection structure is provided with the 1st connection object member, the 2nd connection object member, and the connection part which connects the 1st, 2nd connection object member, and the material of this connection part was mentioned above. It is preferable that the connection structure is a conductive particle or a conductive material containing the above-described conductive particles and a binder resin. It is preferable that the connection part is formed of the above-mentioned conductive particles or a connection structure formed of a conductive material containing the above-mentioned conductive particles and a binder resin. When the conductive particles are used, the connecting portion itself is the conductive particles. That is, the first and second connection target members are connected by the conductive particles.

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

The connection structure 51 shown in FIG. 4 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, 53. Prepare The connection portion 54 is formed of a conductive material containing the conductive particles 1. It is preferable that the conductive material has a thermosetting property, and the connection portion 54 is formed by thermosetting the conductive material. In addition, in FIG. 4, the conductive particles 1 are schematically illustrated for convenience of illustration. Instead of the conductive particles 1, conductive particles 1A, 1B and 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 front surface (lower surface). The first electrode 52a and the second electrode 53a 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 method for manufacturing the connection structure is not particularly limited. As an example of the method for manufacturing the connection structure, the conductive material is arranged between the first connection target member and the second connection target member to obtain a laminated body, and then the laminated body is heated and pressed. Methods and the like. The pressure applied is about 9.8×10 ^{4 to} 4.9×10 ⁶ Pa. The heating temperature is about 120 to 220°C.

Specific examples of the connection target member include electronic components such as a semiconductor chip, a capacitor and a diode, and electronic components such as a printed circuit board, a flexible printed circuit board, a glass epoxy substrate and a circuit board such as a glass substrate. The connection target member is preferably an electronic component. The conductive particles are preferably used for electrical connection of electrodes in electronic parts.

Examples of the electrodes provided on the connection target member include metal electrodes such as gold electrodes, nickel electrodes, tin electrodes, aluminum electrodes, silver electrodes, SUS electrodes, copper electrodes, molybdenum electrodes, and tungsten electrodes. When the member to be connected is a flexible printed board, the electrode is preferably a gold electrode, a nickel electrode, a tin electrode or a copper electrode. When the member to be connected is a glass substrate, the electrode is preferably an aluminum electrode, a copper electrode, a molybdenum electrode or a tungsten electrode. When the above-mentioned electrode is an aluminum electrode, it may be an electrode formed of only aluminum or an electrode in which an aluminum layer is laminated on the surface of a metal oxide layer. Examples of the material of 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 to the following examples.

(Example 1)
(1) Preparation of Base Particles To a monomer solution containing 80 parts by weight of tetramethylolmethane tetraacrylate and 20 parts by weight of acrylonitrile, 1.5 parts by weight of benzoyl peroxide as a polymerization catalyst was added and dissolved to prepare a monomer solution. Obtained. This monomer solution was added to 700 mL of a 3 wt% polyvinyl alcohol aqueous solution, and the mixture was stirred and suspended to obtain a monomer suspension.

Then, the monomer suspension was heated to 85° C. to start the polymerization reaction, and this state was maintained for 10 hours until the reaction was completed. The obtained solid content was filtered, washed with hot water to remove polyvinyl alcohol, and then classified to obtain base particles A having a particle diameter of 3.0 μm.

(2) Core Material Adhesion Step The base particles A were etched and washed with water. Next, the base material particles A were added to 100 mL of the palladium catalyzed liquid containing 8% by weight of the palladium catalyst and stirred. Then, it filtered and wash|cleaned. The base particles A were added to a 0.5 wt% dimethylamine borane solution having a pH of 6 to obtain base particles A to which palladium was attached.

(3) Conductive Portion Forming Step The base material particles A to which palladium was attached were stirred and dispersed in 300 mL of ion-exchanged water for 3 minutes to obtain a dispersion liquid. Next, 1 g of nickel particle slurry (average particle size 150 nm, Mohs hardness 5) was added to the above dispersion over 3 minutes to obtain a suspension of base material particles A to which the core substance was attached. After thoroughly washing the surface-activated base material particles A with water, the dispersion liquid was obtained by adding to 500 parts by weight of distilled water and dispersing.

A first nickel plating solution (pH 4.0) containing nickel sulfate 0.044 mol/L, sodium hypophosphite 0.56 mol/L, sodium citrate 0.10 mol/L and phosphorous acid 2.50 mol/L. , Baume degree 10) was prepared. Furthermore, a second nickel plating solution containing nickel sulfate 0.66 mol/L, sodium hypophosphite 0.84 mol/L and sodium citrate 0.15 mol/L (pH 4.0, Baume degree 1.5) is prepared. did.

While stirring the obtained dispersion liquid at 60° C., the first nickel plating liquid was gradually added dropwise to the suspension liquid to perform electroless nickel plating, and the nickel-phosphorus conductive portion (thickness 40 nm, 1 μm ² 20 holes) were formed, and then the suspension was filtered, added to 500 parts by weight of distilled water, and dispersed to obtain a dispersion liquid. The second nickel plating solution was gradually added dropwise to the dispersion while stirring the resulting dispersion at 60° C., electroless nickel plating was performed, and the nickel-phosphorus conductive part (thickness 60 nm, 1 μm ² 0 holes per hole) were formed. Then, the suspension is filtered to take out the particles, washed with water, and dried to dispose a nickel-phosphorus conductive layer (thickness 0.1 μm) on the surface of the base material particle A, and the surface is a conductive layer. To obtain conductive particles.

(Example 2)
Conductive particles were obtained in the same manner as in Example 1 except that the nickel particle slurry was changed to an alumina particle slurry (average particle size 150 nm, Mohs hardness 9).

(Example 3)
Conductive particles were obtained in the same manner as in Example 1, except that the nickel particle slurry was not used and protrusions were formed by adjusting the amount of precipitation to be partially changed when the conductive portion was formed.

(Example 4)
Conductive particles were obtained in the same manner as in Example 1 except that no protrusion was formed without using the core substance.

(Example 5)
Conductive particles were obtained in the same manner as in Example 1 except that the base material particles A were changed to organic-inorganic hybrid particles (base material particles B).

(Example 6)
The composition of the second nickel plating solution was changed, the thickness of the nickel-phosphorus conductive layer (thickness 0.1 μm) in Example 1 was changed to 90 nm, and the thickness of the outer surface of the conductive portion was changed. Conductive particles were obtained in the same manner as in Example 1 except that a gold layer (thickness: 10 nm) was formed by electroless gold plating to form a multilayer conductive portion.

(Example 7)
The sodium hypophosphite 0.56 mol/L of the first nickel plating solution was changed to dimethylamine borane 0.37 mol/L, and the sodium hypophosphite 0.84 mol/L of the second nickel plating solution was changed. Conductive particles were obtained in the same manner as in Example 1 except that dimethylamine borane was changed to 0.55 mol/L.

(Example 8)
Conductive particles were obtained in the same manner as in Example 1 except that the concentration of phosphorous acid in the first nickel plating solution was changed to 1.50 mol/L (Baume degree 8).

(Example 9)
Conductive particles were obtained in the same manner as in Example 1 except that the concentration of phosphorous acid in the first nickel plating solution was changed to 3.00 mol/L (Baume degree 11).

(Example 10)
Conductive particles were obtained in the same manner as in Example 1 except that the concentration of phosphorous acid in the first nickel plating solution was changed to 3.50 mol/L (Baume degree 12).

(Example 11)
Conductive particles were obtained in the same manner as in Example 1 except that 1.50 mol/L of phosphorous acid was added to the second nickel plating solution (Baume degree 8).

(Example 12)
Conductive particles were obtained in the same manner as in Example 1 except that 2.00 mol/L of phosphorous acid was added to the second nickel plating solution (Baume degree 9).

(Example 13)
Conductive particles were obtained in the same manner as in Example 1 except that 3.00 mol/L of phosphorous acid was added to the second nickel plating solution (Baume degree 11).

(Example 14)
A base material particle C was prepared in which the base material particles A differed only in the particle diameter and the particle diameter was 2.25 μm. Conductive particles were obtained in the same manner as in Example 1 except that the base particles A were changed to the base particles C.

(Example 15)
The base particles A differed only in the particle size, and the base particles D having a particle size of 5.25 μm were prepared. Conductive particles were obtained in the same manner as in Example 1 except that the base particle A was changed to the base particle D.

(Example 16)
(1) Preparation of Insulating Particles In a 1000 mL separable flask equipped with a 4-neck separable cover, a stirring blade, a three-way cock, a cooling tube and a temperature probe, 100 mmol of methyl methacrylate and N,N,N-trimethyl were prepared. A monomer composition containing 1 mmol of -N-2-methacryloyloxyethylammonium chloride and 1 mmol of 2,2'-azobis(2-amidinopropane) dihydrochloride was added to ion-exchanged water so that the solid content was 5% by weight. Then, the mixture was stirred at 200 rpm, and polymerization was performed at 70° C. for 24 hours in a nitrogen atmosphere. After the reaction was completed, it was freeze-dried to obtain insulating particles having an ammonium group on the surface and having an average particle size of 220 nm and a CV value of 10%.

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

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

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

(Comparative Example 1)
Conductive particles were obtained in the same manner as in Example 1 except that the concentration of phosphorous acid in the first nickel plating solution was changed to 4.50 mol/L (Baume degree 14).

(Comparative example 2)
Conductive particles were obtained in the same manner as in Example 1 except that phosphorous acid was not added to the first nickel plating solution.

(Evaluation)
(1) Initial Connection Resistance The conductive particles obtained were added to "Structbond XN-5A" manufactured by Mitsui Chemicals Co., Inc. so that the content of the conductive particles was 10% by weight, and dispersed to obtain an anisotropic conductive paste. It was made.

A transparent glass substrate having an ITO electrode pattern having an L/S of 20 μm/20 μm on its upper surface was prepared. Further, a semiconductor chip having a gold electrode pattern having 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 so as to have a thickness of 30 μm to form an anisotropic conductive paste layer. Next, the semiconductor chip was laminated 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 5 MPa is applied to form 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 4-terminal method. The average value of the two connection resistances was calculated. From the relationship of voltage=current×resistance, the connection resistance can be obtained by measuring the voltage when a constant current is applied. The initial connection resistance was judged according to the following criteria.

[Evaluation criteria for initial connection resistance]
○ ○: Connection resistance is 2.0Ω or less ○: Connection resistance exceeds 2.0Ω and 3.0Ω or less △: Connection resistance exceeds 3.0Ω and 5.0Ω or less ×: Connection resistance exceeds 5.0Ω

(2) Connection resistance after reliability test (conduction reliability)
The connection structure obtained in the above (1) Evaluation of initial connection resistance was left under 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 in the above (1) Evaluation of initial connection resistance. The connection resistance after the reliability test was judged according to the following criteria.

[Criteria for connection resistance after reliability test]
○ ○: The average value of the connection resistance (after leaving) is less than 125% compared to the average value of the connection resistance (before leaving) ○: The average of the connecting resistance (after leaving) compared to the average value of the connection resistance (before leaving) The value is 125% or more and less than 150%. Δ: The average value of the connection resistance (after leaving) is 150% or more and less than 200% compared to the average value of the connection resistance (before leaving). ×: The average of the connecting 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 the connection resistance after the above (2) reliability test, the obtained connection structure was left under the conditions of 85° C. and 85% relative humidity. Regarding the tendency of the connection resistance to increase even after the conductive particles before leaving the connection structure were left under the conditions of 85° C. and 85% relative humidity, the above (2) reliability test was performed. The same tendency as the evaluation result of the connection resistance of was observed.

Further, the evaluation results of the connection resistance after the reliability test of Examples 4 and 15 and Comparative Example 2 are all “Δ”, but the concrete numerical value of the connection resistance after the reliability test is shown in Example 4. , 15 were superior to Comparative Example 2. That is, Comparative Example 2 was inferior to Examples 4 and 15 in connection resistance after the reliability test.

1, 1A, 1B... Conductive particles 1Ba... Protrusions 2... Base material particles 3, 3B... Conductive part (first conductive part, conductive part including holes)
3a, 3Ba... Hole 3Bb... Protrusion 4... Second conductive portion 5... Core material 6... Insulating material 51... Connection structure 52... First connection object member 52a... First electrode 53... Second connection object Member 53a...Second electrode 54...Connection part

Claims (11)

Base material particles,
On the outer surface of the base material particles, a conductive portion arranged so as to contact the base material particles,
There is a hole in the conductive portion,
The conductive portion has a thickness of 50 nm or more,
In the first region having a thickness of 40 nm from the inner surface of the conductive portion toward the outer side in the thickness direction of the conductive portion, there are 8 or more and 50 or less holes having a diameter of 1 nm or more and 20 nm or less per 1 μm ^2. Conductive particles. The conductive particle according to claim 1, wherein 50 or less holes having a diameter of 1 nm or more and 20 nm or less are present per 1 μm ^{2 in} the conductive portion. No holes having a diameter of 1 nm or more and 20 nm or less exist in the second region except the first region of the conductive portion, or 20 holes having a diameter of 1 nm or more and 20 nm or less per 1 μm ^2. The conductive particles according to claim 1 or 2 , which are present in an amount of less than 3. The conductive portion comprises a nickel conductive particles according to any one of claims 1-3. The particle size of the base particle is 1μm or more and 5μm or less, the conductive particles according to any one of claims 1-4. Wherein the substrate particles are resin particles or organic-inorganic hybrid particles, conductive particles according to any one of claims 1-5. The conductive particles according to claim 6 , wherein the base material particles are resin particles. The conductive portion has a plurality of projections on the outer surface, the conductive particles according to any one of claims 1-7. The conductive portion comprises an insulating material disposed on the outer surface of the conductive particles according to any one of claims 1-8. And conductive particles according to any one of claims 1 to 9 and a binder resin, conductive material. A first connection target member having a first electrode on its surface;
A second connection target member having a second electrode on the surface;
A connecting portion connecting the first connection target member and the second connection target member,
The material of the connecting portion is the conductive particles according to any one of claims 1 to 10 , or a conductive material containing 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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