JP2012155952A - Conductive particle, anisotropic conductive material and connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive particle capable of enhancing conduction reliability, and also to provide an anisotropic conductive material using the conductive particle.SOLUTION: The conductive particle 1 includes: a base material particle 2; a conductive layer 3 arranged on the surface 2a of the base material particle 2; a first solder layer 4 arranged on the outer surface 3a of the conductive layer 3; and a second solder layer 5 arranged on the outer surface 4a of the first solder layer 4. The melting point of the first solder layer 4 is lower than that of the second solder layer 5. The anisotropic conductive material contains the conductive particles 1 and a binder resin.

Description

  The present invention relates to conductive particles that can be used, for example, for connection between electrodes, and more particularly, conductive particles having base particles and a conductive layer disposed on the surface of the base particles, and The present invention relates to an anisotropic conductive material using conductive particles and a connection structure.

  Conductive particles are used for connection between an IC chip and a flexible printed circuit board, connection between liquid crystal driving IC chips, connection between an IC chip and a circuit board having an ITO electrode, and the like. For example, after the conductive particles are arranged between the electrode of the IC chip and the electrode of the circuit board, the electrodes can be electrically connected by bringing the conductive particles into contact with the electrodes by heating and pressurization.

  The conductive particles are dispersed in a binder resin and are also used as an anisotropic conductive material.

  As an example of the conductive particles, Patent Document 1 listed below includes resin particles, a nickel plating layer covering the surface of the resin particles, and a solder layer covering the surface of the nickel plating layer. Conductive particles are disclosed.

  Patent Literature 2 below discloses conductive particles including resin particles and a copper layer provided on the surface of the resin particles. Patent Document 2 describes that such a conductive particle is not disclosed in a specific embodiment, but a good electrical connection can be obtained in connection of opposing circuits.

JP-A-9-306231 JP 2003-323813 A

  In the conductive particles described in Patent Document 1, the solder layer between the electrode and the nickel layer may not be sufficiently wet and spread during connection between the electrodes. For this reason, for example, the connection reliability between the solder layer and the electrode may be lowered because the electrode and the solder layer are not sufficiently contacted and joined.

  As described in Patent Document 2, with conductive particles having a copper layer on the surface, the contact area between the electrode and the copper layer tends to be small, and the connection reliability between the copper layer and the electrode tends to be relatively low.

  Further, in the conductive particles having a copper layer on the surface, the copper layer may be oxidized when the conductive particles are stored for a long period of time or when the conductive particles are exposed to high temperature and high humidity. If the electrodes are electrically connected using conductive particles having an oxidized copper layer, there is a problem that the connection resistance increases.

  An object of the present invention is to provide conductive particles capable of improving connection reliability when used for connection between electrodes in a connection structure, and an anisotropic conductive material and a connection structure using the conductive particles. Is to provide.

  According to a wide aspect of the present invention, base particles, a conductive layer disposed on the surface of the base particles, a first solder layer disposed on the outer surface of the conductive layer, and the first And a second solder layer disposed on the outer surface of the first solder layer, wherein the first solder layer has a melting point lower than the melting point of the second solder layer. The

  In a specific aspect of the conductive particle according to the present invention, when the conductive layer has a single-layer structure or a laminated structure of two or more layers, and the conductive layer has a single-layer structure, the conductive layer When the conductivity of the layer is higher than the conductivity of the first solder layer and the second solder layer, and the conductive layer has a laminated structure of two or more layers, the conductivity of the outermost layer of the conductive layer The conductivity is higher than the conductivity of the first solder layer and the second solder layer.

  In another specific aspect of the conductive particle according to the present invention, when the conductive layer has a single-layer structure or a laminated structure of two or more layers, and the conductive layer has a single-layer structure, When the melting point of the conductive layer is higher than the melting points of the first solder layer and the second solder layer, and the conductive layer has a laminated structure of two or more layers, the melting point of the outermost layer of the conductive layer is Higher than the melting points of the first solder layer and the second solder layer.

  In still another specific aspect of the conductive particles according to the present invention, the tin content in the second solder layer is greater than the tin content in the first solder layer.

  The average particle diameter of the conductive particles according to the present invention is preferably 0.1 μm or more and 50 μm or less. The substrate particles are preferably resin particles. The conductive particles according to the present invention are preferably conductive particles used by being dispersed in a binder resin.

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

  In a specific aspect of the anisotropic conductive material according to the present invention, a flux is further included.

  The connection structure according to the present invention includes a first connection target member, a second connection target member, and a connection part that electrically connects the first and second connection target members. The connecting portion is formed of conductive particles configured according to the present invention, or is formed of an anisotropic conductive material including the conductive particles and a binder resin.

  In the conductive particles according to the present invention, the conductive layer is disposed on the surface of the base particle, the first solder layer is disposed on the outer surface of the conductive layer, and the first solder layer Since the second solder layer is disposed on the outer surface of the first solder layer, the melting point of the first solder layer is lower than the melting point of the second solder layer, so that the conductive particles according to the present invention are connected. When used for connection between electrodes in a structure, connection reliability can be improved.

FIG. 1 is a cross-sectional view schematically showing conductive particles according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing conductive particles according to the second embodiment of the present invention. FIG. 3 is a front sectional view schematically showing a connection structure using an anisotropic conductive material including conductive particles and a binder resin according to the first embodiment of the present invention. FIG. 4 is a front cross-sectional view schematically showing an enlarged connection portion between conductive particles and electrodes in the connection structure shown in FIG. 3.

  Hereinafter, the present invention will be described in detail.

  The conductive particles according to the present invention include substrate particles, a conductive layer disposed on the surface of the substrate particles, a first solder layer disposed on the outer surface of the conductive layer, and the first A second solder layer disposed on the outer surface of the one solder layer. The melting point of the first solder layer is lower than the melting point of the second solder layer. The conductive layer has a single-layer structure or a stacked structure of two or more layers. The conductive layer may have a single-layer structure or a laminated structure of two or more layers. That is, the conductive layer may be a single layer or a multilayer.

  When connecting the electrodes using conductive particles, the conductive particles are sandwiched between the electrodes, heated and pressurized, and heat is applied to the conductive particles from the outside of the conductive particles. In this case, the heat applied to the conductive particles is first transmitted to the second solder layer, and then transmitted to the first solder layer via the second solder layer. Therefore, the heating temperature of the first solder layer tends to be lower than the heating temperature of the second solder layer.

  First and second solder layers are disposed on the outer surface of the conductive layer, and the melting point of the first solder layer is lower than the melting point of the second solder layer. The timing at which the solder layer melts can be approached. For this reason, the movement of the particle | grains resulting from a solder layer melting in steps by heating and pressurization can be suppressed. That is, the particle part of the base particle and the conductive layer in the conductive particle is difficult to move. For this reason, the outer solder layer easily spreads well and the solder layer is easily disposed around the contact portion between the electrode and the conductive layer or the inner solder layer. For this reason, the bonding strength between the conductive particles and the electrode is greatly improved.

  Therefore, the connection reliability of the connection structure using the conductive particles according to the present invention can be improved. As a result, for example, in a connection structure using an anisotropic conductive material containing conductive particles for connection between electrodes, even if an impact such as dropping or vibration is applied, poor connection between the electrodes hardly occurs.

  On the other hand, if the melting points of the inner first solder layer and the outer second solder layer are the same, the second solder layer has melted first, and the first solder layer has melted. The time that you are not doing becomes longer. As a result, the movement of the particles, particularly the movement of the particle portion between the base particle and the conductive layer is likely to occur.

  In order to further enhance the effect of suppressing the movement of the particle portion between the base particle and the conductive layer, the melting point of the first solder layer should be 0.1 ° C. or more lower than the melting point of the second solder layer. It is preferably 0.5 ° C. or lower, more preferably 1 ° C. or higher. From the viewpoint of bringing the melting timing of the first and second solder layers closer, the absolute value of the difference between the melting point of the first solder layer and the melting point of the second solder layer is not particularly limited, but preferably 50 ° C or lower, more preferably 30 ° C or lower, still more preferably 10 ° C or lower.

  When the conductive layer has a single-layer structure, the conductivity of the conductive layer is preferably higher than the conductivity of the first solder layer and the second solder layer. Furthermore, when the conductive layer has a laminated structure of two or more layers, the conductivity of the outermost layer of the conductive layer is higher than the conductivity of the first solder layer and the second solder layer. preferable. By making the conductivity of the conductive layer (in the case of a single layer) or the outermost layer of the conductive layer (in the case of a multilayer) higher than the conductivity of the first and second solder layers, the connection resistance between the electrodes can be further increased. Can be lowered. When electrically connecting between electrodes using the electroconductive particle which concerns on this invention, it is preferable to make the said electroconductive layer contact an electrode. On the other hand, even if the conductive layer is not in contact with the electrode, the presence of the conductive layer tends to reduce the connection resistance.

  Furthermore, the first and second solder layers are disposed on the outer surface of the inner conductive layer, thereby preventing oxidation of the inner conductive layer. For this reason, a copper layer, a nickel layer, a silver layer, or the like that is relatively easily oxidized can be used as the conductive layer. A copper layer, a nickel layer, a silver layer, or the like has high conductivity while allowing oxidation to proceed, and enables a connection resistance between electrodes to be reduced.

  When the conductive layer has a single layer structure, the melting point of the conductive layer is preferably higher than the melting points of the first solder layer and the second solder layer. Furthermore, when the conductive layer has a laminated structure of two or more layers, the melting point of the outermost layer of the conductive layer is preferably higher than the melting points of the first solder layer and the second solder layer. In these cases, when the conductive particles are used to connect the electrodes in the connection structure by heating, the first and second solder layers can be melted before the conductive layer, or Only the first and second solder layers can be melted. Therefore, the conductive layer and the electrode can be more easily brought into contact with each other, or the contact area between the first and second solder layers and the electrode can be further increased. Can be achieved more reliably.

  The tin content in the second solder layer is preferably greater than the tin content in the first solder layer. In this case, it is easy to satisfy the above relationship between the melting point of the second solder layer and the melting point of the first solder layer. Furthermore, the adhesion between the second solder layer having a relatively large tin content and the electrode can be further enhanced. Therefore, the conduction reliability in the connection structure can be further increased.

  Furthermore, when the first and second solder layers are disposed on the surface of the conductive layer, the connection target member can be reconnected when a conduction failure occurs during temporary crimping between the electrodes of the connection target member. It becomes easy to peel off.

  Moreover, it is preferable that the electroconductive particle which concerns on this invention is the electroconductive particle disperse | distributed and used in binder resin. The conductive particles according to the present invention are preferably dispersed in a binder resin and used as an anisotropic conductive material. When the anisotropic conductive material is used for the connection between the electrodes in the connection structure, the connection between the electrodes is easy. For example, without disposing conductive particles one by one on the electrode provided on the connection target member, the conductive particles can be formed on the electrode by simply coating or laminating an anisotropic conductive material on the connection target member. Can be placed. Furthermore, after an anisotropic conductive material layer is formed on the connection target member, the other electrodes are stacked on the anisotropic conductive material layer so that the electrodes face each other, and the electrodes are electrically connected. it can. Therefore, the manufacturing efficiency of the connection structure in which the electrodes of the connection target members are connected can be increased. When electrically connecting the electrodes, the conductive layer is preferably brought into contact with the electrodes. Furthermore, since not only the conductive particles but also the binder resin exists between the connection target members, the connection target members can be firmly adhered, and the connection reliability can be improved.

  The conductive particles described in JP-A-9-306231 are not used by being dispersed in a binder resin. This is because the conductive particles have a large particle size, and thus the conductive particles are not preferable for dispersing the conductive particles in a binder resin and using them as an anisotropic conductive material. In the example of Patent Document 2, the surface of resin particles having a particle size of 650 μm is coated with a conductive layer, and conductive particles having a particle size of several hundreds of μm are obtained. It is not used as a mixed anisotropic conductive material.

  In JP-A-9-306231, when connecting the electrodes of the connection target member using conductive particles, one conductive particle is placed on one electrode, and then the electrode is placed on the conductive particle. After placing, it is heating. By heating, the solder layer is melted and joined to the electrode. However, the operation of placing conductive particles on the electrode is complicated. Further, since there is no resin layer between the connection target members, the connection reliability tends to be low.

(Conductive particles)
Hereinafter, the present invention will be clarified by describing specific embodiments and examples of the present invention with reference to the drawings.

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

  A conductive particle 1 shown in FIG. 1 includes a base particle 2, a conductive layer 3, a first solder layer 4, and a second solder layer 5. The melting point of the first solder layer 4 is lower than the melting point of the second solder layer 5.

  The conductive layer 3 is disposed on the surface 2 a of the base particle 2. The conductive layer 3 covers the surface 2 a of the base particle 2. In the conductive particle 1, the conductive layer 3 is directly laminated on the surface 2 a of the base particle 2. The conductive layer 3 has a single layer structure. The conductive layer 3 is an inner layer.

  The first solder layer 4 is disposed on the outer surface 3 a of the conductive layer 3. The first solder layer 4 is directly laminated on the outer surface 3 a of the conductive layer 3. The first solder layer 4 covers the outer surface 3 a of the conductive layer 3. The first solder layer 4 is an intermediate layer.

  The second solder layer 5 is disposed on the outer surface 4 a of the first solder layer 4. The second solder layer 5 is directly laminated on the outer surface 4 a of the first solder layer 4. The second solder layer 5 covers the outer surface 4 a of the first solder layer 4. The second solder layer 5 is an outer layer.

  In FIG. 2, the electroconductive particle which concerns on the 2nd Embodiment of this invention is shown with sectional drawing.

  A conductive particle 11 shown in FIG. 2 includes a base particle 2, a conductive layer 12, a first solder layer 13, and a second solder layer 14. The melting point of the first solder layer 13 is lower than the melting point of the second solder layer 14. The conductive particles 11 and the conductive particles 1 differ only in the conductive layer.

  The conductive layer 12 is disposed on the surface 2 a of the base particle 2. The conductive layer 12 covers the surface 2 a of the base particle 2. The conductive layer 12 has a two-layer structure and is a multilayer. The conductive layer 12 has an inner conductive layer 21 (first conductive layer) and an outer conductive layer 22 (second conductive layer). The outer conductive layer 22 is the outermost layer of the conductive layer 12.

  The first solder layer 13 is disposed on the outer surface 12 a of the conductive layer 12. The first solder layer 13 is directly laminated on the outer surface 12 a of the conductive layer 12. The first solder layer 13 is disposed on the surface of the outer conductive layer 22 that is the outermost layer of the conductive layer 12. The first solder layer 13 covers the outer surface 12 a of the conductive layer 12 and the outer surface of the outer conductive layer 22.

  The second solder layer 14 is disposed on the outer surface 13 a of the first solder layer 13. The second solder layer 14 is directly laminated on the outer surface 13 a of the first solder layer 13. The second solder layer 14 covers the outer surface 13 a of the first solder layer 13.

  Like the conductive particles 1 and 11, the conductive layer may have a single-layer structure or a two-layer stacked structure. Furthermore, the conductive layer may have a stacked structure of two or more layers.

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

  The substrate particles are preferably resin particles formed of a resin. When connecting the electrodes, the conductive particles are generally compressed after the conductive particles are arranged between the electrodes. When the substrate particles are resin particles, the conductive particles are easily deformed by compression, and the contact area between the conductive particles and the electrode is increased. For this reason, the conduction | electrical_connection reliability between electrodes can be improved. Furthermore, the flexibility of the conductive particles can be increased when the substrate particles are not particles formed of metal such as nickel or glass but resin particles formed of resin. When the flexibility of the conductive particles is high, damage to the electrode in contact with the conductive particles can be suppressed.

  Examples of the resin for forming the resin particles include polyolefin resin, acrylic resin, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polyethylene terephthalate, polysulfone, and polyphenylene. Examples thereof include oxides, polyacetals, polyimides, polyamideimides, polyetheretherketones, and polyethersulfones. Since the conductive particles can be appropriately deformed by compression, the resin particles are formed of a polymer obtained by polymerizing one or more polymerizable monomers having an ethylenically unsaturated group. Is preferred.

  Examples of the inorganic substance for forming the inorganic particles include silica and carbon black. Examples of the organic / inorganic hybrid particles include organic / inorganic hybrid particles formed of a crosslinked alkoxysilyl polymer and an acrylic resin.

  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 conductive layer is preferably made of metal. The metal which comprises a conductive layer is not specifically limited. Examples of the metal include tin, gold, silver, copper, platinum, palladium, zinc, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium and cadmium, and alloys thereof. It is done. In addition, tin-doped indium oxide (ITO) can also be used as the metal. Especially, since it is excellent in electroconductivity, a copper layer, a nickel layer, a gold layer, a silver layer, and a palladium layer are preferable. As for the said metal, only 1 type may be used and 2 or more types may be used together.

  A method of forming a conductive layer on the surface of the substrate particle, a method of forming a first solder layer on the surface of the conductive layer, and a method of forming a second solder layer on the surface of the first solder layer There is no particular limitation. As a method for forming the conductive layer and the first and second solder layers, for example, a method by electroless plating, a method by electroplating, a method by physical collision, a method by mechanochemical reaction, physical vapor deposition or physical Examples thereof include a method by adsorption, and a method of coating the surface of resin particles with a metal powder or a paste containing a metal powder and a binder. Among these, a method using electroless plating, electroplating, or physical collision is preferable. Examples of the method by physical vapor deposition include methods such as vacuum vapor deposition, ion plating, and ion sputtering. Further, in the method based on the physical collision, for example, a theta composer or the like is used.

  In the conductive particles according to the present invention, when the conductive layer has a single-layer structure, the conductive layer is preferably a copper layer, a nickel layer, or a palladium layer, and more preferably a copper layer. Moreover, when the said conductive layer has a laminated structure of two or more layers, it is preferable that the outermost layer of the said conductive layer is a copper layer, a nickel layer, or a palladium layer, and it is more preferable that it is a copper layer. In this case, the connection resistance between the electrodes can be further reduced. In addition, a solder layer can be more easily formed on the surface of these preferable conductive layers.

  The conductivity of the copper layer, nickel layer, gold layer, silver layer and palladium layer is higher than the conductivity of the first and second solder layers. For this reason, the conduction | electrical_connection reliability between electrodes can be improved. On the other hand, the copper layer and the nickel layer also have properties that are relatively easily oxidized. However, in the conductive particles according to the present invention, when the conductive layer is a copper layer and a nickel layer, the first and second solder layers are disposed on the surfaces of the copper layer and the nickel layer. The oxidation of the layer and the nickel layer can be effectively suppressed.

  Examples of the metal other than tin constituting the first and second solder layers include the metal constituting the conductive layer described above. The first and second solder layers may be alloys. Specific examples of the metal constituting the first and second solder layers include bismuth, silver and indium. By adjusting the weight ratio of tin and metal other than tin in the first and second solder layers, the melting points of the first and second solder layers can be adjusted.

  From the viewpoint of further improving the connection reliability in the connection structure, the tin content in the second solder layer is preferably larger than the tin content in the first solder layer, and is preferably 5% by weight or more. The amount is preferably large, more preferably 10% by weight or more, still more preferably 20% by weight or more.

  From the viewpoint of further improving the connection reliability in the connection structure, the content of tin is preferably 60% by weight or more, more preferably 65% by weight or more, preferably 80% by weight in 100% by weight of the second solder layer. % Or less, more preferably 75% by weight or less, and still more preferably 70% by weight or less.

  As an example of the first and second solder layers, a first solder layer a1 containing 42% by weight of tin and 58% by weight of bismuth is formed, and a second solder containing 70% by weight of tin and 30% by weight of bismuth. The electroconductive particle A which formed the layer a2 is demonstrated.

  A composition containing 42 wt% tin and 58 wt% bismuth is a eutectic composition. In the conductive particles A, the first solder layer a1 melts at about 139 ° C., while the second solder layer a2 does not melt unless the temperature exceeds 139 ° C. Therefore, in this conductive particle A, the temperature at which the first solder layer a1 and the second solder layer a2 begin to melt is different. On the other hand, when the conductive particles are heated, the heating temperature of the second solder layer a2 is higher than the heating temperature of the first solder layer a1. As a result, when the melting point of the first solder layer a1 is lower than the melting point of the second solder layer a2, compared to the case where the melting point of the first solder layer and the melting point of the second solder layer are the same, The timing at which the first solder layer a1 and the second solder layer a2 melt is close. Further, in this conductive particle A, since the tin content in the second solder layer a2 is larger than the tin content in the first solder layer a1, the second solder layer a2 adheres well to the electrode. .

  Like the conductive particles A, the first and second solder layers preferably contain bismuth. When the first and second solder layers contain bismuth as in the conductive particles A, the content of bismuth in the second solder layer 100 wt% is preferably 25 wt% or more, preferably 40 wt%. The bismuth content in 100% by weight of the first solder layer is preferably 35% by weight or more, more preferably 55% by weight or more, and preferably less than 60% by weight. However, in the conductive particles according to the present invention, the melting points of the first and second solder layers can be adjusted by using silver or indium other than bismuth.

  The thicknesses of the conductive layer and the first and second solder layers are each preferably 10 nm or more, more preferably 50 nm or more, still more preferably 100 nm or more, preferably 2000 nm or less, more preferably 1000 nm or less. When the thickness of the conductive layer and the first and second solder layers is equal to or greater than the above lower limit, the conductivity is sufficiently high. When the thickness of the conductive layer and the first and second solder layers is not more than the above upper limit, the difference in thermal expansion coefficient between the substrate particles, the conductive layer, and the first and second solder layers is reduced, and the conductive layer and The solder layer is unlikely to peel off.

  The method of forming the first solder layer on the surface of the conductive layer and the method of forming the second solder layer on the surface of the first solder layer may be a physical collision method. preferable. The first solder layer is preferably disposed on the surface of the conductive layer by physical impact, and the second solder layer is disposed on the surface of the first solder layer by physical impact. It is preferable to arrange | position.

  Conventionally, the particle diameter of conductive particles having a solder layer on the outer surface layer of the conductive layer has been about several hundred μm. This is because the solder layer could not be formed uniformly even if conductive particles having a particle size of several tens of μm and the surface layer being a solder layer were obtained. On the other hand, when the solder layer is formed by optimizing the dispersion conditions during electroless plating, the conductive particles have a particle size of several tens of μm, in particular, conductive particles having a particle size of 0.1 μm or more and 50 μm or less. Even when obtaining conductive particles, the solder layer can be formed uniformly on the surface of the conductive layer. Further, even when a theta composer is used, even when conductive particles having a particle size of 50 μm or less are obtained, the solder layer can be uniformly formed on the surface of the conductive layer.

  When the conductive layer has a laminated structure of two or more layers, the thickness of the outermost layer of the conductive layer is preferably 5 nm or more, more preferably 10 nm or more, still more preferably 25 nm or more, particularly preferably 50 nm or more, preferably 1000 nm. Below, more preferably 500 nm or less. When the thickness of the outermost layer of the conductive layer is not less than the above lower limit, the conductivity is sufficiently high. When the thickness of the outermost layer of the conductive layer is not more than the above upper limit, the difference in the coefficient of thermal expansion between the base particles and the outermost layer of the conductive layer becomes small, and the outermost layer of the conductive layer is hardly peeled off.

  The average particle diameter of the conductive particles is preferably 0.1 μm or more, more preferably 1 μm or more, preferably 100 μm or less, more preferably 80 μm or less, still more preferably 50 μm or less, and particularly preferably 40 μm or less. When the average particle diameter of the conductive particles is not less than the above lower limit and not more than the above upper limit, the contact area between the conductive particles and the electrode is sufficiently large, and aggregated conductive particles are formed when the conductive layer is formed. It becomes difficult. 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.

  Since the size is suitable for the conductive particles in the anisotropic conductive material and the distance between the electrodes can be further reduced, the average particle diameter of the conductive particles is preferably 0.1 μm or more, more preferably Is 100 μm or less, more preferably 50 μm or less.

  The “average particle size” of the conductive particles indicates a number average particle size. The average particle diameter of the conductive particles can be obtained by observing 50 arbitrary conductive particles with an electron microscope or an optical microscope and calculating an average value.

  The electroconductive particle which concerns on this invention may be equipped with the insulating particle arrange | positioned on the surface of a solder layer. It is preferable that the number of insulating particles arranged on the surface of the second solder layer is plural.

  When the conductive particles including the insulating 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, the insulating particles are 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. It should be noted that insulating particles between the solder layer and the electrodes in the conductive particles can be easily eliminated by pressurizing the conductive particles with the two electrodes when connecting the electrodes.

  Specific examples of the insulating resin constituting the insulating particles 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 the method for attaching insulating particles to the surface of the solder 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 particles are difficult to be detached, a method in which the insulating particles are attached to the surface of the solder layer via a chemical bond is preferable.

(Anisotropic conductive material)
The anisotropic conductive material according to the present invention includes a binder resin and the above-described conductive particles. That is, the conductive particles contained in the anisotropic conductive material according to the present invention include base particles, a conductive layer disposed on the surface of the base particles, and a surface of the conductive layer. A first solder layer and a second solder layer disposed on the outer surface of the first solder layer. The melting point of the first solder layer is lower than the melting point of the second solder layer.

  The anisotropic conductive material according to the present invention is preferably in a liquid state and is preferably an anisotropic conductive paste.

  The binder resin is not particularly limited. As the binder resin, for example, an 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.

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

  The binder resin is preferably a thermosetting resin. In this case, by heating at the time of electrically connecting the electrodes, the solder layer of conductive particles can be melted and the binder resin can be cured. For this reason, the connection between electrodes by a solder layer or a conductive layer and the connection of the connection object member by binder resin can be performed simultaneously.

  The anisotropic conductive material according to the present invention preferably contains a curing agent in order to cure the binder resin.

  The said hardening | curing agent is not specifically limited. Examples of the curing agent include imidazole curing agents, amine curing agents, phenol curing agents, polythiol curing agents, and acid anhydride curing agents. As for a hardening | curing agent, only 1 type may be used and 2 or more types may be used together.

  The anisotropic conductive material according to the present invention preferably further contains a flux. By using the flux, it becomes difficult to form an oxide film on the surface of the solder layer, and the oxide film formed on the surface of the solder layer or the electrode can be effectively removed.

  The flux is not particularly limited. As the flux, a flux generally used for soldering or the like can be used. Examples of the flux include zinc chloride, a mixture of zinc chloride and an inorganic halide, a mixture of zinc chloride and an inorganic acid, a molten salt, phosphoric acid, a derivative of phosphoric acid, an organic halide, hydrazine, an organic acid, and pine resin. Is mentioned. Only 1 type of flux may be used and 2 or more types may be used together.

  Examples of the molten salt include ammonium chloride. Examples of the organic acid include lactic acid, citric acid, stearic acid, glutamic acid, and hydrazine. Examples of the pine resin include activated pine resin and non-activated pine resin. The flux is preferably rosin. By using rosin, the connection resistance between the electrodes is further reduced.

  The rosin is a rosin composed mainly of abietic acid. The flux is preferably rosins, and more preferably abietic acid. By using this preferable flux, the connection resistance between the electrodes can be further reduced.

  The said flux may be disperse | distributed in binder resin and may adhere on the surface of electroconductive particle.

  The anisotropic conductive material according to the present invention may contain a basic organic compound in order to adjust the activity of the flux. Examples of the basic organic compound include aniline hydrochloride and hydrazine hydrochloride.

  From the viewpoint of further suppressing sedimentation of the conductive particles during storage of the anisotropic conductive material, the content of the binder resin is preferably 30% by weight or more, more preferably in 100% by weight of the anisotropic conductive material. It is 50% by weight or more, more preferably 80% by weight or more, preferably 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 above lower limit and not more than the above upper limit, the sedimentation of the conductive particles is less likely to occur, and the connection reliability of the connection target member connected by the anisotropic conductive material is further increased. Can be increased.

  When a curing agent is used, the content of the curing agent is preferably 0.01 parts by weight or more, more preferably 0.1 parts by weight or more, preferably 100 parts by weight or less with respect to 100 parts by weight of the binder resin. More preferably, it is 50 parts by weight or less. When the content of the curing agent is not less than the above lower limit and not more than the above upper limit, the binder resin can be sufficiently cured, and a residue derived from the curing agent is less likely to occur after curing.

  In 100% by weight of the anisotropic conductive material, the content of the conductive particles is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, and preferably 20% by 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 conductive particles are more unlikely to settle and the conduction reliability between the electrodes is further enhanced.

  In 100% by weight of the anisotropic conductive material, the content of the flux is 0% by weight or more, preferably 0.5% by weight or more, preferably 30% by weight or less, more preferably 25% by weight or less. The anisotropic conductive material may not contain a flux. When the flux content is not less than the above lower limit and not more than the above upper limit, an oxide film is more difficult to be formed on the surface of the solder layer, and the oxide film formed on the solder layer or the electrode surface is more effective. Can be removed.

  The anisotropic conductive material according to the present invention includes, for example, a filler, an extender, a softener, a plasticizer, a polymerization catalyst, a curing catalyst, a colorant, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, Various additives such as a lubricant, an antistatic agent or a flame retardant may be further contained.

  The method for dispersing the conductive particles in the binder resin is not particularly limited, and a conventionally known dispersion method can be used. Examples of the method for dispersing the conductive particles in the binder resin include, for example, a method in which the conductive particles are added to the binder resin and then kneaded and dispersed with a planetary mixer or the like. The conductive particles are dispersed in water or an organic solvent. After uniformly dispersing using a homogenizer, etc., adding into a binder resin, kneading and dispersing with a planetary mixer, etc., and after diluting the binder resin with water or an organic solvent, the conductive particles are The method of adding, kneading | mixing with a planetary mixer etc., and dispersing is mentioned.

  The anisotropic conductive material according to the present invention can be used as an anisotropic conductive paste, anisotropic conductive ink, anisotropic conductive adhesive, anisotropic conductive film, or anisotropic conductive sheet. When the anisotropic conductive material containing the conductive particles of the present invention is used as a film-like adhesive such as an anisotropic conductive film or an anisotropic conductive sheet, the film-like shape containing the conductive particles is used. A film-like adhesive that does not contain conductive particles may be laminated on the adhesive. However, as described above, the anisotropic conductive material according to the present invention is preferably in a liquid state, and is preferably an anisotropic conductive paste.

(Connection structure)
A connection structure can be obtained by connecting the connection target members using the anisotropic conductive material according to the present invention.

  The connection structure includes a first connection target member, a second connection target member, and a connection portion that electrically connects the first and second connection target members. The part is preferably formed of conductive particles according to the present invention, or formed of an anisotropic conductive material containing the conductive particles and a binder resin. It is preferable that the connection portion is formed by curing the anisotropic conductive material.

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

  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 that electrically connects the first and second connection target members 52 and 53. 54. The connection portion 54 is formed by curing an anisotropic conductive material including the conductive particles 1 and the binder resin. In FIG. 3, the conductive particles 1 are schematically shown for convenience of illustration.

  A plurality of electrodes 52 b are provided on the upper surface 52 a of the first connection target member 52. A plurality of electrodes 53 b are provided on the lower surface 53 a of the second connection target member 53. The electrode 52 b and the electrode 53 b 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 anisotropic 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 a method of applying pressure. By heating and pressing, the first and second solder layers 4 and 5 of the conductive particles 1 are melted, and the electrodes 52 b and 53 b are electrically connected by the conductive particles 1. At this time, the conductive layer 3 is preferably brought into contact with the electrodes 52b and 53b. When the binder resin is a thermosetting resin, the binder resin is cured, and the first and second connection target members 52 and 53 are connected by the cured binder resin.

The pressure of the said pressurization is about 9.8-10 < ⁴ > -4.9 * 10 < ⁶ > Pa. The temperature of the said heating is about 120-220 degreeC.

  FIG. 4 is an enlarged front sectional view of a connection portion between the conductive particles 1 and the electrodes 52b and 53b in the connection structure 51 shown in FIG. As shown in FIG. 4, in the connection structure 51, after the first and second solder layers 4 and 5 of the conductive particles 1 are melted by heating and pressurizing the laminated body, the melted solder layer portion. X is in sufficient contact with the electrodes 52b and 53b. In particular, since the melting point of the first solder layer 4 is lower than the melting point of the second solder layer 5, the second solder layer 5 between the conductive layer 3 and the electrodes 52b and 53b is effectively wetted in a short period of time. Spread and eliminated. As a result, the movement of the particle portions of the base particle 2 and the conductive layer 3 in the conductive particle 1 in the lateral direction is less likely to occur. As a result, the first and second solder layers 4 and 5 can be present more and more reliably around the contact portion between the conductive particles 1 and the electrodes 52b and 53b, and a good fillet can be formed. Can do. For this reason, the connection reliability of the connection structure 51 can be improved. Moreover, the connection resistance between electrodes can be made still lower by making the conductive layer 3 contact the electrodes 52b and 53b. In general, the flux is gradually deactivated by heating.

  Specific examples of the connection target member include electronic components such as semiconductor chips, capacitors, and diodes, and circuit boards such as printed boards, flexible printed boards, and glass boards.

  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 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 metal oxide include indium oxide doped with a trivalent metal element and zinc oxide doped with a trivalent metal element. Examples of the trivalent metal element include Sn, Al, and Ga.

  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.

Example 1
(1) Production of conductive particles Electroless copper plating of divinylbenzene resin particles (“Micropearl SP-220” manufactured by Sekisui Chemical Co., Ltd.) having an average particle diameter of 20 μm and a base copper plating of 1 μm thickness on the surface of the resin particles A layer was formed and particles X were obtained. Thereafter, using a theta composer (manufactured by Tokuju Kogakusha Co., Ltd.), fine powder of solder (containing 42% by weight of tin and 58% by weight of bismuth and having an average particle diameter of 200 nm) on the surface of the copper layer of the obtained particles X Was melted to form a first solder layer having a thickness of 1 μm on the surface of the copper layer. Next, using a theta composer (manufactured by Tokuju Kogakusha Co., Ltd.), on the surface of the obtained first solder layer, an average particle diameter of 200 nm containing fine solder powder (70% by weight of tin and 30% by weight of bismuth) ) Was melted to form a second solder layer having a thickness of 1 μm on the surface of the first solder layer.

  In this way, a 1 μm thick copper layer is formed on the surface of the resin particles, and a 1 μm thick first solder layer (containing 42 wt% tin) is formed on the surface of the copper layer. Then, conductive particles were produced in which a second solder layer (containing 70 wt% tin) having a thickness of 1 μm was formed on the surface of the first solder layer. In the obtained conductive particles, the melting point of the copper layer as the conductive layer is higher than the melting points of the first and second solder layers. The melting point of the first solder layer is 45 ° C. lower than the melting point of the second solder layer, and the absolute value of the difference between the melting points is 45 ° C.

(2) Production of anisotropic conductive material 100 parts by weight of TEPIC-PAS B22 (manufactured by Nissan Chemical Industries, specific gravity 1.4) which is a binder resin, 15 parts by weight of TEP-2E4MZ (manufactured by Nippon Soda Co., Ltd.) which is a curing agent And 5 parts by weight of weakly active rosin, and after adding 10 parts by weight of the conductive particles immediately after production, the mixture is stirred for 5 minutes at 2000 rpm using a planetary stirrer to produce an anisotropic conductive paste. An anisotropic conductive material was obtained.

(Example 2)
The resin particles were changed to divinylbenzene resin particles (“Micropearl-SP230” manufactured by Sekisui Chemical Co., Ltd.) having an average particle diameter of 30 μm, and the thickness of the copper layer formed by electrolytic copper plating was changed from 1 μm to 2.5 μm. The amount of solder fine powder used to form the first solder layer is increased to change the thickness of the first solder layer from 1 μm to 2.5 μm, and the second solder layer is formed. Conductive particles and an anisotropic conductive material were obtained in the same manner as in Example 1 except that the amount of the solder fine powder was increased and the thickness of the second solder layer was changed from 1 μm to 2.5 μm.

(Example 3)
Solder fine powder (containing 42% by weight of tin and 58% by weight of bismuth and having an average particle diameter of 200 nm) for forming the first solder layer, and containing fine powder of solder (65% by weight of tin and 35% by weight of bismuth) And the solder fine powder (average particle diameter 200 nm containing 70% by weight of tin and 30% by weight of bismuth) for forming the second solder layer, Conductive particles and an anisotropic conductive material were obtained in the same manner as in Example 1 except that the average particle size was changed to 75% by weight of tin and 25% by weight of bismuth. Note that the melting point of the copper layer as the conductive layer is higher than the melting points of the first and second solder layers. The melting point of the first solder layer is 30 ° C. lower than the melting point of the second solder layer, and the absolute value of the difference between the melting points is 30 ° C.

Example 4
Divinylbenzene resin particles having an average particle diameter of 20 μm (“Micropearl SP-220” manufactured by Sekisui Chemical Co., Ltd.) were subjected to electroless nickel plating to form a base nickel plating layer having a thickness of 0.3 μm on the surface of the resin particles. Next, the resin particles on which the base nickel plating layer was formed were subjected to electrolytic nickel plating to form a nickel layer having a thickness of 1 μm, whereby particles Y were obtained. Thereafter, using a theta composer (manufactured by Tokuju Kogakusha Co., Ltd.), on the surface of the nickel layer of the obtained particle Y, solder fine powder (average particle diameter of 200 nm containing 42 wt% tin and 58 wt% bismuth) Was melted to form a first solder layer having a thickness of 1 μm on the surface of the copper layer. Next, using a theta composer (manufactured by Tokuju Kogakusha Co., Ltd.), on the surface of the obtained first solder layer, an average particle diameter of 200 nm containing fine solder powder (70% by weight of tin and 30% by weight of bismuth) ) Was melted to form a second solder layer having a thickness of 1 μm on the surface of the first solder layer.

  Thus, a nickel layer having a thickness of 1 μm is formed on the surface of the resin particles, and a first solder layer having a thickness of 1 μm (containing 42 wt% tin) is formed on the surface of the nickel layer. Then, conductive particles were produced in which a second solder layer (containing 70 wt% tin) having a thickness of 1 μm was formed on the surface of the first solder layer. In the obtained conductive particles, the melting point of the nickel layer as the conductive layer is higher than the melting points of the first and second solder layers.

(Comparative Example 1)
Solder particles (tin: bismuth = 43 wt%: 57 wt%, average particle diameter of 15 μm) were prepared. An anisotropic conductive material was obtained in the same manner as in Example 1 except that the solder particles were used.

(Comparative Example 2)
The particles X obtained in Example 1 were prepared. Using theta composer (manufactured by Tokuju Kogakusha Co., Ltd.), solder fine powder (containing 42% by weight of tin and 58% by weight of bismuth and having an average particle size of 200 nm) is melted on the surface of the copper layer of the obtained particles. Then, a 2 μm thick solder layer was formed on the surface of the copper layer.

  Thus, a 1 μm-thick copper layer is formed on the surface of the resin particles, and a 2 μm-thick solder layer (single layer, containing 42% by weight of tin) is formed on the surface of the copper layer. Conductive particles were produced. An anisotropic conductive material was obtained in the same manner as in Example 1 except that the obtained conductive particles were used.

(Comparative Example 3)
The particles Y obtained in Example 4 were prepared. Using a theta composer (manufactured by Tokuju Kogakusha Co., Ltd.), solder fine powder (containing 42% by weight of tin and 58% by weight of bismuth and having an average particle diameter of 200 nm) is melted on the surface of the nickel layer of the obtained particles. Then, a 2 μm thick solder layer was formed on the surface of the nickel layer.

  In this way, a nickel layer having a thickness of 1 μm is formed on the surface of the resin particle, and a solder layer having a thickness of 2 μm (single layer, containing 42% by weight of tin) is formed on the surface of the nickel layer. Conductive particles were produced. An anisotropic conductive material was obtained in the same manner as in Example 1 except that the obtained conductive particles were used.

(Evaluation)
(1) Production of Connection Structure An FR-4 substrate having a gold electrode pattern with an L / S of 200 μm / 200 μm formed on the upper surface was prepared. In addition, a polyimide substrate (flexible substrate) having a gold electrode pattern with L / S of 200 μm / 200 μm formed on the lower surface was prepared.

  After stirring the obtained anisotropic conductive material on the upper surface of the FR-4 substrate, it is applied so that the thickness is twice the average particle diameter of the conductive particles contained in the anisotropic conductive material. And an anisotropic conductive material layer was formed.

  Next, a polyimide substrate (flexible substrate) was laminated on the upper surface of the anisotropic conductive material layer so that the electrodes face each other. Then, while adjusting the temperature of the head so that the temperature of the anisotropic conductive material layer is 185 ° C., a pressure heating head is placed on the upper surface of the semiconductor chip and a pressure of 2.0 MPa is applied to apply the anisotropic conductive material. The material layer was cured at 185 ° C. to obtain a connection structure.

(2) Conduction test between upper and lower electrodes 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 results are shown in Table 1 below, where “◯” indicates that the average value of the connection resistance is 2.0Ω or less and “X” indicates that the average value of the connection resistance exceeds 2Ω.

(3) Connection reliability A (percentage of conductive particles with traces moved)
By observing the cross section of the obtained connection structure, it is confirmed whether or not there are traces of the conductive particles moving laterally with the melting of the solder layer with respect to 100 conductive particles sandwiched between the upper and lower electrodes. Was evaluated. In addition, regarding the electroconductive particle with the trace which moved, there is little quantity of the solder layer which exists in the contact part of this electroconductive particle and an electrode.

[Criteria for connection reliability A]
○: Ratio of conductive particles with traces of movement is less than 50% ×: Ratio of conductive particles with traces of movement is 50% or more

(4) Connection reliability B (impact resistance test)
The obtained connection structure was dropped from a position with a height of 70 cm, and the impact resistance was evaluated by confirming the continuity of each solder joint. The results are shown in Table 1 below where “○” indicates that the rate of increase in resistance value from the initial resistance value is 50% or less, and “X” indicates that the rate of increase in resistance value from the initial resistance value exceeds 50%. It was.

  The results are shown in Table 1 below.

  In the connection structure using the anisotropic conductive material obtained in Examples 1 to 4, the first and second solder layers are solidified after being melted, and the conductive layer and the electrode are in contact with each other. It was.

DESCRIPTION OF SYMBOLS 1 ... Conductive particle 2 ... Base particle 2a ... Surface 3 ... Conductive layer 3a ... Surface 4 ... 1st solder layer 4a ... Outer surface 5 ... 2nd solder layer 11 ... Conductive particle 12 ... Conductive layer 12a ... Surface 13 ... first solder layer 13a ... outer surface 14 ... second solder layer 21 ... inner conductive layer 22 ... outer conductive layer 51 ... connection structure 52 ... first connection target member 52a ... upper surface 52b ... Electrode 53 ... second connection target member 53a ... lower surface 53b ... electrode 54 ... connection portion X ... molten solder layer portion

Claims (10)

Substrate particles,
A conductive layer disposed on the surface of the substrate particles;
A first solder layer disposed on an outer surface of the conductive layer;
A second solder layer disposed on an outer surface of the first solder layer,
Conductive particles in which the melting point of the first solder layer is lower than the melting point of the second solder layer. The conductive layer has a one-layer structure or a laminated structure of two or more layers,
When the conductive layer has a single-layer structure, the conductivity of the conductive layer is higher than the conductivity of the first solder layer and the second solder layer,
2. When the conductive layer has a laminated structure of two or more layers, the conductivity of the outermost layer of the conductive layer is higher than the conductivity of the first solder layer and the second solder layer. The electroconductive particle as described in. The conductive layer has a one-layer structure or a laminated structure of two or more layers,
When the conductive layer has a single layer structure, the melting point of the conductive layer is higher than the melting points of the first solder layer and the second solder layer,
3. The melting point of the outermost layer of the conductive layer is higher than the melting points of the first solder layer and the second solder layer when the conductive layer has a laminated structure of two or more layers. The electroconductive particle as described in.   4. The conductive particle according to claim 1, wherein a content of tin in the second solder layer is higher than a content of tin in the first solder layer.   The electroconductive particle of any one of Claims 1-4 whose average particle diameter is 0.1 micrometer or more and 50 micrometers or less.   The electroconductive particle of any one of Claims 1-5 whose said base material particle is a resin particle.   The electroconductive particle of any one of Claims 1-6 which is the electroconductive particle disperse | distributed and used in binder resin.   An anisotropic conductive material containing the electroconductive particle of any one of Claims 1-6, and binder resin.   The anisotropic conductive material according to claim 8, further comprising a flux. A first connection target member;
A second connection target member;
A connecting portion electrically connecting the first and second connection target members;
The connection portion is formed of the conductive particles according to any one of claims 1 to 6, or is formed of an anisotropic conductive material including the conductive particles and a binder resin. Structure.

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