JP2013152867A - Conductive particle, anisotropic conductive material, and connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive particle and an anisotropic conductive material which are capable of enhancing electric connection reliability against a thermal shock of a connection structure in the case of obtaining the connection structure by connecting electrodes.SOLUTION: A conductive particle 1 according to the invention, includes particles 2 having copper on the surfaces thereof, and a solder layer 3 disposed on the surface of copper in contact with the copper, and including a metal including tin and forming an intermetallic compound of three component system with tin and copper. An anisotropic conductive material according to the invention includes the conductive particle 1 and binder resin.

Description

  The present invention relates to conductive particles that can be used to electrically connect electrodes of various connection target members such as a flexible printed circuit board, a glass substrate, a glass epoxy substrate, and a semiconductor chip. The present invention also relates to an anisotropic conductive material using the conductive particles, and a connection structure using the conductive particles.

  Pasty or film-like anisotropic conductive materials are widely known. In the anisotropic conductive material, a plurality of conductive particles are dispersed in a binder resin or the like.

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

  For example, when the electrode of the semiconductor chip and the electrode of the glass substrate are electrically connected by the anisotropic conductive material, an anisotropic conductive material containing conductive particles is disposed on the glass substrate. Next, the semiconductor chips are stacked, and heated and pressurized. Accordingly, the anisotropic conductive material is cured, and the electrodes are electrically connected through the conductive particles to obtain a connection structure.

  As an example of the conductive particles, Patent Document 1 below discloses that the solidus temperature is 125 ° C. or higher, the peak temperature is 200 ° C. or lower, and the temperature difference between the solidus temperature and the peak temperature. Discloses conductive particles (low melting point metal particles) having a temperature of 15 ° C. or higher. Patent Document 1 discloses an anisotropic conductive material in which the conductive particles are dispersed in a thermosetting resin.

WO2008 / 111615A1

  When conventional conductive particles as described in Patent Document 1 are used, the connection resistance between the electrodes may increase when the connection structure is subjected to a thermal shock such as a thermal cycle. For this reason, there exists a problem that the conduction | electrical_connection reliability between electrodes is low.

  An object of the present invention is to use conductive particles that can enhance electrical connection reliability against thermal shock of the connection structure when the connection structure is obtained by connecting the electrodes, and the conductive particle is used. An anisotropic conductive material and a connection structure using the conductive particles are provided.

  According to a wide aspect of the present invention, particles having copper on the surface and disposed on the surface of copper so as to be in contact with copper, containing tin, and forming a ternary intermetallic compound with tin and copper A conductive particle is provided, comprising a solder layer containing a metal to be used.

  On the specific situation with the electroconductive particle which concerns on this invention, the said metal is nickel, cobalt, gold | metal | money, silver, manganese, zinc, palladium, or iron.

  In another specific aspect of the conductive particle according to the present invention, the metal is present on the inner surface of the solder layer, or the metal is present on the outer surface of the solder layer.

  In another specific aspect of the conductive particle according to the present invention, the metal is present on the inner surface of the solder layer.

  In still another specific aspect of the conductive particle according to the present invention, the metal is present on the outer surface of the solder layer.

  In another specific aspect of the conductive particle according to the present invention, the metal is present on the inner surface and the outer surface of the solder layer.

  In another specific aspect of the conductive particles according to the present invention, the metal is contained in the solder layer using metal particles.

  On the other specific situation of the electroconductive particle which concerns on this invention, the said metal exists in the said solder layer with an agglomerate.

  In another specific aspect of the conductive particles according to the present invention, the particles having copper on the surface thereof include base material particles and a copper layer disposed on the surface of the base material particles, and the copper layer The solder layer is disposed on the outer surface of the copper layer so as to be in contact with the copper layer.

  The conductive particles according to the present invention are preferably conductive particles used for connection of a copper electrode.

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

  A connection structure according to the present invention connects a first connection target member having a first electrode, a second connection target member having a second electrode, and the first and second connection target members. The connection portion is formed of the above-described conductive particles, or is formed of an anisotropic conductive material including the conductive particles and a binder resin. An electrode and the second electrode are electrically connected by the conductive particles.

  On the specific situation with the connection structure which concerns on this invention, a said 1st electrode or a said 2nd electrode is a copper electrode.

  The conductive particles according to the present invention are disposed on the surface of the copper so as to come into contact with the particles having copper on the surface, and contain tin, and tin and copper and a ternary intermetallic compound. And a solder layer containing a metal to be formed, so that when the connection structure is obtained by connecting the electrodes using the conductive particles according to the present invention, the electrical connection reliability against the thermal shock of the connection structure Can increase the sex.

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 cross-sectional view schematically showing conductive particles according to the third embodiment of the present invention. FIG. 4 is a front cross-sectional view schematically showing a connection structure using conductive particles according to the first embodiment of the present invention. FIG. 5 is a front cross-sectional view schematically showing an enlarged connection portion between conductive particles and electrodes in the connection structure shown in FIG. 4.

  Hereinafter, the present invention will be described in detail.

The electroconductive particle which concerns on this invention is equipped with the particle | grains which have copper on the surface, and the solder layer arrange | positioned on the surface of copper so that copper may be contact | connected. The solder layer contains tin and a metal that forms a ternary intermetallic compound with tin and copper (hereinafter sometimes referred to as metal X). In the conductive particles according to the present invention, the solder layer in contact with copper contains tin, and contains metal X that forms ternary intermetallic compounds with tin and copper. The metal X is preferably a metal that forms an intermetallic compound of (Cu, X) ₆ Sn ₅ or Cu ₆ (Sn, X) ₅ with tin and copper. The metal tube compound is, for example, a compound in which a plurality of metal elements are bonded at a certain ratio.

Since the conductive particles according to the present invention have the above-described configuration, when the connection structure is obtained by connecting the electrodes, the electrical connection reliability against the thermal shock of the connection structure can be improved. . For example, even if the connection structure is exposed to a high temperature or is subjected to a cooling and heating cycle, the connection resistance between the electrodes is hardly increased, and the conduction reliability is improved. This is because when the solder layer does not contain metal X, copper forms a coarse intermetallic compound of tin and Cu ₆ Sn ₅ , and cracks are generated from the intermetallic compound interface, whereas the solder layer is metal When X is contained, a small grain boundary of the enriched layer of metal X (Cu, X) ₆ Sn ₅ or Cu ₆ (Sn, X) ₅ is formed at the interface between copper and tin, which serves as a barrier layer really it results growth can be suppressed intermetallic compound of Cu ₆ Sn ₅ by suppressing the diffusion of copper, reduces the occurrence of cracks from the intermetallic compound interface Cu ₆ Sn _5, because the reliability becomes good It is.

  From the viewpoint of further improving the electrical connection reliability against thermal shock, the solder layer preferably contains the metal using metal particles. From the viewpoint of further improving the electrical connection reliability against thermal shock, in the conductive particles according to the present invention, it is preferable that the metal X is present as agglomerates in the solder layer.

  The “granule” means a metal lump or metal particle present in the solder layer.

  When the metal X is an agglomerate, the size of the agglomerate is not particularly limited, but is preferably 1 nm or more, more preferably 10 nm or more, preferably 10000 nm or less, more preferably 1000 nm or less.

  Examples of the metal X include nickel, cobalt, gold, silver, manganese, zinc, palladium, and iron. The metal X is preferably nickel, cobalt, gold, silver, manganese, zinc, palladium, or iron, more preferably nickel, cobalt, or iron, and even more preferably nickel. By using such a preferable metal, the electrical connection reliability against the thermal shock of the connection structure is further increased. As for the said metal X, only 1 type may be used and 2 or more types may be used together. When the metal X is nickel, cobalt, or iron, only one kind of the metal X may be used, or two or more kinds may be used in combination.

  From the viewpoint of lowering the melting point of the entire solder layer, the metal X is preferably unevenly distributed in the thickness direction of the solder layer. The metal X may partially exist in the thickness direction of the solder layer. The metal X in the solder layer may change continuously from the inner surface side to the outer surface side in the thickness direction of the solder layer, or may change stepwise.

  It is preferable that the metal X is present on the inner surface of the solder layer or the metal X is present on the outer surface of the solder layer. It is preferable that the metal X is present more in the inner region of the solder layer than the central region, or the metal X is present in the outer region of the solder layer than the central region. In this case, cracking and peeling are less likely to occur at the interface between the solder layer and the copper or copper electrode in the particles having copper on the surface, and the electrical connection reliability against thermal shock of the connection structure Becomes even higher. When the metal X is present on the inner surface of the solder layer, or when the metal X is present on the outer surface of the solder layer, the metal X is present on the inner surface and the outer surface of the solder layer. Cases are also included.

  The metal X is preferably present on the inner surface of the solder layer. It is preferable that the metal X is present more in the inner region of the solder layer than in the central region. In this case, cracking and peeling are less likely to occur at the interface between the copper and the solder layer in the particles having copper on the surface, and the electrical connection reliability against thermal shock of the connection structure is further increased.

  The metal X is preferably present on the outer surface of the solder layer. It is preferable that the metal X is present more in the region outside the solder layer than in the central region. In this case, cracking and peeling are less likely to occur at the interface between the electrode such as the copper electrode and the solder layer, and the electrical connection reliability against thermal shock of the connection structure is further increased. In particular, when the copper electrode is electrically connected, cracking and peeling are hardly caused at the interface between the copper electrode and the solder layer.

  The metal is preferably present on the inner surface and the outer surface of the solder layer. It is particularly preferable that the metal X is present more in the inner and outer regions of the solder layer than in the central region. In this case, cracking and peeling are less likely to occur at the interface between the copper and the solder layer in the particles having copper on the surface, and further cracking and peeling are caused at the interface between the electrode such as the copper electrode and the solder layer. It becomes difficult. For this reason, the electrical connection reliability with respect to the thermal shock of a connection structure becomes still higher.

  The region inside the solder layer is preferably a region having a thickness of 1/3 on the inner surface side of the solder layer. That is, the inner region of the solder layer is preferably a region of 1/3 of the thickness of the solder layer from the inner surface to the outer side of the solder layer. The region outside the solder layer is preferably a region having a thickness of 1/3 on the outer surface side of the solder layer. That is, the outer region of the solder layer is preferably a region of の the thickness of the solder layer from the outer surface to the inner side of the solder layer. It is preferable that the center area | region of the said solder layer is a center area | region of 1/3 of the thickness in the said solder layer.

  As a method of making the metal X in the solder layer different in the thickness direction of the solder layer, when forming the solder layer, a material for forming an inner region in the thickness direction and a solder in an outer region in the thickness direction Examples thereof include a method of differentiating the material forming the layer portion, a method of performing plating to form a solder layer, mixing a part of the composition constituting the solder layer as a metal powder, and eutectoid.

  The conductive particles according to the present invention are preferably conductive particles used for connection of a copper electrode. In this case, cracking and peeling are less likely to occur at the interface between the copper electrode and the solder layer, and the electrical connection reliability against thermal shock of the connection structure is further increased.

  In the case of the conductive particles used for the connection of the copper electrode, it is particularly preferable that the metal X is present on the outer surface of the solder layer, and further, the metal X in the region outside the solder layer than in the central region. It is particularly preferable that a large amount of be present.

  Hereinafter, details of the conductive particles, the anisotropic conductive material, and the connection structure will be described.

(Details of conductive particles)
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 particles 2 and a solder layer 3. The particles 2 have copper on the surface. The solder layer 3 is disposed on the surface of copper so as to be in contact with copper in the particles 2. The solder layer 3 is laminated on the surface of copper in the particles 2. The particles 2 are covered with a solder layer 3. The solder layer 3 contains tin and a metal X that forms a ternary intermetallic compound with tin and copper.

  The particles 2 have base material particles 6 and a copper layer 7. The copper layer 7 is disposed on the surface of the base particle 6. The copper layer 7 is laminated on the surface of the base particle 6. The copper in the particles 2 is a copper layer 7. The solder layer 3 is disposed on the outer surface of the copper layer 7. The solder layer 3 is laminated on the outer surface of the copper layer 7. The copper layer 7 is covered with the solder layer 3. The solder layer 3 and the copper layer 7 are conductive layers. The solder layer 3 is an outer layer and is the outermost layer. The copper layer 7 is an inner layer.

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

  The conductive particles 11 shown in FIG. 2 include particles 12 and a solder layer 3. The particles 12 have copper on the surface. The solder layer 3 is disposed on the surface of copper so as to be in contact with copper in the particles 12. The conductive particles 11 and the conductive particles 1 differ only in the particles having copper on the surface.

  The particle 12 includes a base particle 6, a conductive layer 16, and a copper layer 17. The conductive layer 16 is disposed on the surface of the base particle 6. The copper layer 17 is disposed on the surface of the base particle 6 via the conductive layer 16. The copper layer 17 is laminated on the surface of the conductive layer 16. The solder layer 3 is disposed on the surface of the copper layer 17 so as to be in contact with the copper layer 17.

  In FIG. 3, the electroconductive particle which concerns on the 3rd Embodiment of this invention is shown with sectional drawing.

  The conductive particles 21 shown in FIG. 3 include particles 22 and a solder layer 3. The particles 22 are copper particles and have copper on the surface. That is, the entire particle 22 is copper. The solder layer 3 is disposed on the surface of copper so as to be in contact with copper in the particles 22. The conductive particles 21 and the conductive particles 1 are different only in particles having copper on the surface.

  The particles having copper on the surface may be copper particles or particles having base particles and a conductive layer disposed on the surface of the base particles. The conductive layer disposed on the surface of the substrate particle may have a single-layer structure or a laminated structure of two or more layers. The surface of the conductive layer (excluding the solder layer) disposed on the surface of the substrate particles may be a copper layer. The solder layer may have a single-layer structure or a laminated structure of two or more layers.

  The particles having copper on the surface preferably have base material particles and a copper layer disposed on the surface of the base material particles. In this case, a conductive layer other than the copper layer may be disposed between the base particle and the copper layer. When particles having base material particles and a copper layer arranged on the surface of the base material particles are used, the distance between the electrodes can be controlled with higher accuracy due to the base material particles. Moreover, the usage-amount of an electroconductive component can be reduced.

  Examples of the substrate particles include resin particles, inorganic particles, organic-inorganic hybrid particles, and metal particles. The substrate particles are preferably resin particles or organic-inorganic hybrid particles, and more preferably resin particles.

  The resin particles are made of 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 becomes high. Furthermore, the flexibility of the conductive particles is increased when the substrate particles are resin particles formed of a resin rather than particles of a metal such as nickel or glass. 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, polyether ether ketones, polyether sulfones, divinylbenzene polymers, and divinylbenzene copolymers. Examples of the divinylbenzene copolymer include divinylbenzene-styrene copolymer and divinylbenzene- (meth) acrylic acid ester copolymer. Since the conductive particles are appropriately deformed by compression, the resin particles are preferably formed of a polymer obtained by polymerizing one or more polymerizable monomers having an ethylenically unsaturated group.

  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 other than the copper layer and the solder layer is preferably formed of a metal. The metal which comprises the said conductive layer is not specifically limited. Examples of the metal include tin, gold, silver, platinum, palladium, zinc, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, cadmium, and alloys thereof. In addition, tin-doped indium oxide (ITO) may be used as the metal. Especially, since it is excellent in electroconductivity, 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.

  The method for forming a copper layer (conductive layer), a solder layer (conductive layer), and a conductive layer other than the copper layer and the solder layer on the surface of the particle is not particularly limited. Examples of the method for forming the conductive layer include a method by electroless plating, a method by electroplating, a method by physical collision, a method by mechanochemical reaction, a method by physical vapor deposition or physical adsorption, and a metal powder or metal. Examples thereof include a method of coating the surface of the resin particles with a paste containing a 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.

  The method for forming the solder layer is preferably a physical collision method. The solder layer is preferably disposed on the surface of copper by physical impact, and is preferably laminated on the surface of the copper particles or the copper layer. That is, it is preferable to form a solder layer on the surface of copper by performing a physical collision on the surface of the particles. In the physical collision, it is preferable to use a theta composer.

  The melting point of the solder layer is preferably 450 ° C. or lower. When the metal X is present in the form of agglomerates, the melting point of the solder layer is a melting point other than the agglomerate portion of the metal X. Examples of the metal other than tin and the metal X constituting the solder layer include the metal constituting the conductive layer described above. The solder layer may be an alloy.

  The material constituting the solder layer is preferably a meltable material having a liquidus of 450 ° C. or lower based on JIS Z3001: solvent terminology. When the metal X is present in the form of agglomerates, the liquidus line of the solder layer indicates a liquidus line other than the agglomerated part of the metal X.

  As a composition of the said solder layer, the metal composition containing zinc, gold | metal | money, lead, copper, nickel, cobalt, bismuth, indium etc. other than tin is mentioned, for example. The solder layer is preferably an alloy containing silver, an alloy containing copper, an alloy containing bismuth, or an alloy containing indium, and more preferably an alloy containing bismuth or an alloy containing indium. The solder layer preferably does not contain lead. The solder layer preferably contains indium or bismuth, preferably contains indium, and preferably contains bismuth.

  Furthermore, the solder layer preferably contains a third element such as silver, copper, germanium, or antimony, and more preferably contains a small amount of a third element such as silver, copper, germanium, or antimony. Thereby, refinement of grain boundaries can be expected, and the effects of improving ductility and improving connection reliability can be obtained. The solder layer preferably contains antimony, and more preferably contains a small amount of antimony. In the total 100% by weight of the solder layer, the content of the third element or antimony is preferably 0.1% by weight or more, preferably 1% by weight or less, more preferably 0.5% by weight or less.

  From the viewpoint of further improving the electrical connection reliability against thermal shock, the content of the metal X in the total 100% by weight of the solder layer is preferably 0.01% by weight or more, more preferably 0.05% by weight. % Or more, preferably 0.2% by weight or less, more preferably 0.15% by weight or less.

  From the viewpoint of further improving the electrical connection reliability against thermal shock, the content of the metal X is preferably 0.01% by weight or more, more preferably 0.05% by weight on the inner surface side of the solder layer. As mentioned above, Preferably it is 0.2 weight% or less, More preferably, it is 0.15 weight% or less. From the viewpoint of further improving the electrical connection reliability against thermal shock, the content of the metal X is preferably 0.01% by weight or more, more preferably 0.05% by weight on the outer surface side of the solder layer. As mentioned above, Preferably it is 0.2 weight% or less, More preferably, it is 0.15 weight% or less.

  From the viewpoint of lowering the melting point of the solder layer and further improving the electrical connection reliability against thermal shock, the bismuth content in the total 100% by weight of the solder layer is preferably 50% by weight or more. Preferably it is 55 weight% or more, Preferably it is 65 weight% or less, More preferably, it is 60 weight% or less. The content of the bismuth is most preferably 58% by weight which is a eutectic composition with tin.

  The thickness of the copper layer, the solder layer, and the conductive layer other than the copper layer and the solder layer is preferably 10 nm or more, more preferably 50 nm or more, still more preferably 100 nm or more, preferably 5000 nm or less, more preferably Is 3000 nm or less. When the thickness is not less than the lower limit, the conductivity is sufficiently high. When the thickness is less than or equal to the above upper limit, the difference in coefficient of thermal expansion between the substrate particles and the conductive layer becomes small, and the conductive layer is hardly peeled off.

  In the solder layer, the thickness of the solder layer portion containing the metal X is preferably 50 nm or more, more preferably 100 nm or more, preferably 1000 nm or less, more preferably 500 nm or less.

  The average particle diameter of the conductive particles is preferably 0.1 μm or more, more preferably 1 μm or more, preferably 500 μm or less, more preferably 100 μm or less, still more preferably 80 μm or less, particularly preferably 50 μm or less, and most preferably 40 μm. It is as follows. 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 is further reduced, the average particle diameter of the conductive particles is preferably 0.1 μm or more, more preferably 100 μm or less. More preferably, it is 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 conductive particles may include an insulating material disposed on the surface of the solder layer. It is preferable that there are a plurality of the insulating substances arranged on the surface of the solder layer. The insulating substance is preferably insulating particles.

  When the conductive particles including the insulating material are used for connection between electrodes, a short circuit between adjacent electrodes can be prevented. Specifically, when a plurality of conductive particles are in contact with each other, an insulating material is present between the plurality of electrodes, so that it is possible to prevent a short circuit between electrodes adjacent in the lateral direction instead of between the upper and lower electrodes. In addition, when connecting the electrodes, the insulating particles between the solder layer and the electrodes in the conductive particles can be easily removed by pressurizing the conductive particles with the two electrodes.

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

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

  Examples of a method for attaching an insulating substance 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. Especially, since the said insulating substance cannot separate | separate easily, the method of making the said insulating substance adhere to the surface of the said solder layer through a chemical bond is preferable.

(Details of anisotropic conductive material)
The anisotropic conductive material includes the above-described conductive particles and a binder resin.

  In 100% by weight of the anisotropic conductive material, the content of the conductive particles is preferably 1% by weight or more, more preferably 2% by weight or more, still more preferably 10% by weight or more, and preferably 80% by weight or less. Preferably it is 60 weight% or less. A conductive particle can be easily arrange | positioned between the upper and lower electrodes which should be connected as content of the said electroconductive particle is more than the said minimum and below an upper limit. Furthermore, it becomes difficult to electrically connect adjacent electrodes that should not be connected via a plurality of conductive particles. That is, a short circuit between adjacent electrodes can be further prevented.

Binder resin:
The binder resin preferably contains a thermoplastic compound or a curable compound. The binder resin may contain a thermoplastic compound or may contain a curable compound.

  Examples of the thermoplastic compound include phenoxy resin, urethane resin, (meth) acrylic resin, polyester resin, polyimide resin, and polyamide resin.

  The curable compound preferably includes a curable compound that can be cured by heating. The anisotropic conductive material is an anisotropic conductive material curable by heating, and it is particularly preferable that the binder resin contains a curable compound curable by heating. The curable compound curable by heating may be a curable compound (thermosetting compound) that is not cured by light irradiation, and is curable by both light irradiation and heating (light and light). Thermosetting compound).

  The anisotropic conductive material is an anisotropic conductive material that can be cured by both light irradiation and heating. As the binder resin, a curable compound (photocurable compound) that can be cured by light irradiation. Or a light and thermosetting compound). The curable compound that can be cured by light irradiation may be a curable compound (photocurable compound) that is not cured by heating, and is a curable compound that can be cured by both light irradiation and heating (light and light). Thermosetting compound). The anisotropic conductive material preferably contains a photocuring initiator. The anisotropic conductive material preferably contains a photoradical generator as the photocuring initiator. The anisotropic conductive material preferably contains a thermosetting compound as the curable compound, and further contains a photocurable compound or light and a thermosetting compound. The anisotropic conductive material preferably contains a thermosetting compound and a photocurable compound as the curable compound.

  The curable compound is not particularly limited, and examples thereof include a curable compound having an unsaturated double bond and a curable compound having an epoxy group or a thiirane group.

  Further, from the viewpoint of enhancing the curability of the anisotropic conductive material and further enhancing the conduction reliability between the electrodes, the curable compound preferably includes a curable compound having an unsaturated double bond, It preferably contains a curable compound having a (meth) acryloyl group. The unsaturated double bond is preferably a (meth) acryloyl group. Examples of the curable compound having an unsaturated double bond include an curable compound having no epoxy group or thiirane group and having an unsaturated double bond, and having an epoxy group or thiirane group, Examples thereof include curable compounds having a heavy bond.

  As the curable compound having the (meth) acryloyl group, an ester compound obtained by reacting a (meth) acrylic acid and a compound having a hydroxyl group, an epoxy obtained by reacting (meth) acrylic acid and an epoxy compound ( A (meth) acrylate, a urethane (meth) acrylate obtained by reacting a (meth) acrylic acid derivative having a hydroxyl group with an isocyanate, or the like is preferably used. The “(meth) acryloyl group” refers to an acryloyl group and a methacryloyl group. The “(meth) acryl” refers to acryl and methacryl. The “(meth) acrylate” refers to acrylate and methacrylate.

  The ester compound obtained by making the said (meth) acrylic acid and the compound which has a hydroxyl group react is not specifically limited. As the ester compound, any of a monofunctional ester compound, a bifunctional ester compound, and a trifunctional or higher functional ester compound can be used.

  From the viewpoint of enhancing the curability of the anisotropic conductive material, further improving the conduction reliability between the electrodes, and further enhancing the adhesive strength of the cured product, the anisotropic conductive material is an unsaturated double bond. And a curable compound having both a thermosetting functional group. Examples of the thermosetting functional group include an epoxy group, a thiirane group, and an oxetanyl group. The curable compound having both the unsaturated double bond and the thermosetting functional group is preferably a curable compound having an epoxy group or a thiirane group and having an unsaturated double bond, and thermosetting. It is preferable that it is a curable compound which has both a functional functional group and a (meth) acryloyl group, and it is preferable that it is a curable compound which has an epoxy group or a thiirane group, and has a (meth) acryloyl group.

  The curable compound having an epoxy group or thiirane group and having a (meth) acryloyl group is a part of the epoxy group or part of the curable compound having two or more epoxy groups or two or more thiirane groups. A curable compound obtained by converting a thiirane group into a (meth) acryloyl group is preferred. Such curable compounds are partially (meth) acrylated epoxy compounds or partially (meth) acrylated episulfide compounds.

  The curable compound is preferably a reaction product of a compound having two or more epoxy groups or two or more thiirane groups and (meth) acrylic acid. This reaction product is obtained by reacting a compound having two or more epoxy groups or two or more thiirane groups with (meth) acrylic acid in the presence of a catalyst such as a basic catalyst according to a conventional method. It is preferable that 20% or more of the epoxy group or thiirane group is converted (converted) to a (meth) acryloyl group. The conversion is more preferably 30% or more, preferably 80% or less, more preferably 70% or less. Most preferably, 40% or more and 60% or less of the epoxy group or thiirane group is converted to a (meth) acryloyl group.

  Examples of the partially (meth) acrylated epoxy compound include bisphenol type epoxy (meth) acrylate, cresol novolac type epoxy (meth) acrylate, carboxylic acid anhydride-modified epoxy (meth) acrylate, and phenol novolac type epoxy (meth) acrylate. Is mentioned.

  As the curable compound, a modified phenoxy resin obtained by converting a part of epoxy groups of a phenoxy resin having two or more epoxy groups or two or more thiirane groups or a part of thiirane groups into a (meth) acryloyl group may be used. Good. That is, a modified phenoxy resin having an epoxy group or thiirane group and a (meth) acryloyl group may be used.

  The “phenoxy resin” is generally a resin obtained by reacting, for example, an epihalohydrin and a divalent phenol compound, or a resin obtained by reacting a divalent epoxy compound and a divalent phenol compound. is there.

  The curable compound may be a crosslinkable compound or a non-crosslinkable compound.

  Specific examples of the crosslinkable compound include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, (poly ) Ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, glycerol methacrylate acrylate, pentaerythritol tri (meth) acrylate, tri Examples include methylolpropane trimethacrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, polyester (meth) acrylate, and urethane (meth) acrylate.

  Specific examples of the non-crosslinkable compound include ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) ) Acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, decyl (Meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, and the like.

  Furthermore, examples of the curable compound include oxetane compounds, epoxy compounds, episulfide compounds, (meth) acrylic compounds, phenolic compounds, amino compounds, unsaturated polyester compounds, polyurethane compounds, silicone compounds, and polyimide compounds.

  From the viewpoint of easily controlling the curing of the anisotropic conductive material or further improving the conduction reliability in the connection structure, the curable compound includes a curable compound having an epoxy group or a thiirane group. It is preferable. The curable compound having an epoxy group is an epoxy compound. The curable compound having a thiirane group is an episulfide compound. From the viewpoint of enhancing the curability of the anisotropic conductive material, the content of the compound having an epoxy group or thiirane group is preferably 10% by weight or more, more preferably 20% by weight or more, in 100% by weight of the curable compound. , 100% by weight or less. The total amount of the curable compound may be a curable compound having the epoxy group or thiirane group. From the viewpoint of excellent handleability and further improving the conduction reliability in the connection structure, the compound having the epoxy group or thiirane group is preferably an epoxy compound.

  The anisotropic conductive material preferably contains a curable compound having an epoxy group or a thiirane group and a curable compound having an unsaturated double bond.

  The curable compound having an epoxy group or thiirane group preferably has an aromatic ring. Examples of the aromatic ring include a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, tetracene ring, chrysene ring, triphenylene ring, tetraphen ring, pyrene ring, pentacene ring, picene ring, and perylene ring. Especially, it is preferable that the said aromatic ring is a benzene ring, a naphthalene ring, or an anthracene ring, and it is more preferable that it is a benzene ring or a naphthalene ring. A naphthalene ring is preferred because it has a planar structure and can be cured more rapidly.

  When the thermosetting compound and the photocurable compound are used in combination, the mixing ratio of the photocurable compound and the thermosetting compound is appropriately determined according to the type of the photocurable compound and the thermosetting compound. Adjusted. The anisotropic conductive material preferably contains a photocurable compound and a thermosetting compound in a weight ratio of 1:99 to 90:10, more preferably 5:95 to 60:40, More preferably, it is included at 10:90 to 40:60.

Thermosetting agent:
The anisotropic conductive material preferably contains a thermosetting agent. The thermosetting agent cures the thermosetting compound. As the thermosetting agent, a conventionally known thermosetting agent can be used. As for the said thermosetting agent, only 1 type may be used and 2 or more types may be used together.

  Examples of the thermosetting agent include imidazole curing agents, amine curing agents, phenol curing agents, polythiol curing agents, thermal cation generators, acid anhydrides, and thermal radical generators. Moreover, since the storage stability of an anisotropic conductive material becomes high, a latent hardening | curing agent is preferable. The latent curing agent is preferably a latent imidazole curing agent, a latent polythiol curing agent or a latent amine curing agent. The thermosetting agent may be coated with a polymer material such as polyurethane resin or polyester resin.

  The imidazole curing agent is not particularly limited, and 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2, 4-Diamino-6- [2'-methylimidazolyl- (1 ')]-ethyl-s-triazine and 2,4-diamino-6- [2'-methylimidazolyl- (1')]-ethyl-s- Examples include triazine isocyanuric acid adducts.

  The polythiol curing agent is not particularly limited, and examples include trimethylolpropane tris-3-mercaptopropionate, pentaerythritol tetrakis-3-mercaptopropionate, and dipentaerythritol hexa-3-mercaptopropionate. .

  The amine curing agent is not particularly limited, and hexamethylene diamine, octamethylene diamine, decamethylene diamine, 3,9-bis (3-aminopropyl) -2,4,8,10-tetraspiro [5.5]. Examples include undecane, bis (4-aminocyclohexyl) methane, metaphenylenediamine, and diaminodiphenylsulfone.

  The anisotropic conductive material preferably includes a thermal cation generator, and further includes a thermal cation generator that releases inorganic acid ions upon heating or releases organic acid ions containing boron atoms upon heating. More preferred.

  The thermal cation generator releases inorganic acid ions by heating, or releases organic acid ions containing boron atoms by heating. These thermal cation generators can remove the oxide film on the outer surface of the solder layer and the oxide film on the electrode surface by inorganic acid ions or organic acid ions released by heating. Therefore, when using conductive particles having a solder layer, the use of the specific thermal cation generator greatly contributes to the improvement of the conduction reliability between the electrodes.

The component that releases inorganic acid ions by heating is preferably a compound having SbF ⁶⁻ or PF ⁶⁻ as the anion moiety. The thermal cation generator is preferably a compound having SbF ⁶⁻ as the anion moiety, and is preferably a compound having PF ⁶⁻ as the anion moiety.

  The component that releases an organic acid ion containing a boron atom is preferably a compound having an anion moiety represented by the following formula (2).

  In the above formula (2), X represents a halogen atom. X in the above formula (2) is preferably a chlorine atom, a bromine atom or a fluorine atom, and more preferably a fluorine atom.

  That is, the component that releases an organic acid ion containing a boron atom is more preferably a compound having an anion moiety represented by the following formula (2A).

  The thermal cation generator is preferably a component having a sulfonium cation moiety, and more preferably a component having a sulfonium cation moiety represented by the following formula (1).

  In the above formula (1), R1 is benzyl group, substituted benzyl group, phenacyl group, substituted phenacyl group, allyl group, substituted allyl group, alkoxyl group, substituted alkoxyl group, aryloxy group or substituted Represents a substituted aryloxy group. R2 and R3 each represent the same group as that capable of constituting R1, a linear, branched or cyclic alkyl group having 1 to 18 carbon atoms, or a monocyclic or 6 to 18 carbon atoms Represents a condensed polycyclic aryl group. R1 and R2, R1 and R3, and R2 and R3 may be a cyclic structure bonded to each other. The linear, branched or cyclic alkyl group having 1 to 18 carbon atoms and the monocyclic or condensed polycyclic aryl group having 6 to 18 carbon atoms are fluorine, chlorine, bromine, hydroxyl group and carboxyl group. , A mercapto group, a cyano group, a nitro group, or an azide group.

  The thermal cation generator is more preferably a component having a sulfonium cation moiety represented by the following formula (1A).

In the formula (1A), R1 represents an aryl group or a naphthyl group, R2 represents a hydroxy group or a _CH 3 OCOO group, n represents an integer of 1-3.

  Preferable examples of R1 in the above formula (1A) include a phenyl group, an o-methylphenyl group, an m-methylphenyl group, a p-methylphenyl group, a 1-naphthyl group, and a 2-naphthyl group. R1 in the above formula (1A) is preferably a phenyl group, an o-methylphenyl group, or a 1-naphthyl group. However, R1 may be a group other than these.

In the above formula (1A), the binding site of R2 to the benzene ring is not particularly limited. R2 in the above formula (1A) is preferably bonded to the para position with respect to the S group. The CH ₃ OCOO group in the above formula (1A) is a methoxycarbonyloxy group. R2 in the above formula (1A) is preferably a hydroxy group. N in the formula (1A) is preferably 1.

  The thermal cation generator is particularly preferably a component having a sulfonium cation moiety represented by the following formula (1A-1) or the following formula (1A-2).

In the above formula (1A-1), R1a represents an alkyl group having 1 to 4 carbon atoms, R2 represents a hydroxy group or a CH ₃ OCOO group, m represents 0 or 1, and n represents an integer of 1 to 3. Represent.

R1a in the above formula (1A-1) is preferably a methyl group. M in the formula (1A-1) is preferably 0 so that R1 does not exist. In addition, the coupling | bonding site | part with respect to the benzene ring of R1a in the said Formula (1A-1) is not specifically limited. R1a in the above formula (1A-1) is preferably bonded to the ortho position with respect to the CH ₂ group. The preferable group and number of R2 and n in the formula (1A-1) are the same as the preferable group and number of R2 and n in the formula (1A).

In the formula (1A-2), R2 represents a hydroxy group or a _CH 3 OCOO group, n represents an integer of 1-3. The preferable group and number of R2 and n in the formula (1A-2) are the same as the preferable group and number of R2 and n in the formula (1A).

The thermal cation generator is preferably a sulfonium-based thermal cation generator. The component having the sulfonium cation moiety and the anion moiety of SbF ⁶⁻ , the anion moiety of PF ⁶⁻ , or the anion moiety represented by the above formula (2) acts as a thermal cation generator.

  The content of the thermosetting agent is not particularly limited. The content of the thermosetting agent is preferably 0.01 parts by weight or more, more preferably 1 part by weight or more, preferably 200 parts by weight or less, based on 100 parts by weight of the curable compound that can be cured by heating. The amount is preferably 100 parts by weight or less, more preferably 75 parts by weight or less. When the content of the thermosetting agent is not less than the above lower limit, it is easy to sufficiently cure the anisotropic conductive material. When the content of the thermosetting agent is not more than the above upper limit, it is difficult for an excess thermosetting agent that did not participate in curing after curing to remain, and the heat resistance of the cured product is further enhanced.

  When the thermosetting agent is the thermal cation generator, the content of the thermal cation generator is preferably 0.01 parts by weight or more with respect to 100 parts by weight of the curable compound curable by heating. More preferably 0.05 parts by weight or more, still more preferably 5 parts by weight or more, particularly preferably 10 parts by weight or more, preferably 40 parts by weight or less, more preferably 30 parts by weight or less, still more preferably 20 parts by weight or less. . When the content of the thermal cation generator is not less than the above lower limit and not more than the above upper limit, the anisotropic conductive material is sufficiently thermoset, and the conduction reliability in the connection structure is further enhanced. Furthermore, the oxide film on the outer surface of the solder layer and the oxide film on the electrode surface can be more effectively removed, and the conduction reliability in the connection structure is further enhanced.

  The blending ratio of the conductive particles and the thermal cation generator in the anisotropic conductive material is preferably 1: 1 to 20: 1 by weight, and preferably 2: 1 to 15: 1. More preferred is 5: 2 to 10: 1.

Other ingredients:
The anisotropic conductive material preferably contains a photocuring initiator. The photocuring initiator is not particularly limited. A conventionally known photocuring initiator can be used as the photocuring initiator. From the viewpoint of further improving the connection reliability between the electrodes and the connection reliability of the connection structure, the anisotropic conductive material preferably contains a photoradical generator. As for the said photocuring initiator, only 1 type may be used and 2 or more types may be used together.

  The photocuring initiator is not particularly limited, and is not limited to acetophenone photocuring initiator (acetophenone photoradical generator), benzophenone photocuring initiator (benzophenone photoradical generator), thioxanthone, ketal photocuring initiator (ketal photoradical). Generator), halogenated ketones, acyl phosphinoxides, acyl phosphonates, and the like.

  Specific examples of the acetophenone photocuring initiator include 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, methoxy Examples include acetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, and 2-hydroxy-2-cyclohexylacetophenone. Specific examples of the ketal photocuring initiator include benzyldimethyl ketal.

  The content of the photocuring initiator is not particularly limited. For 100 parts by weight of the curable compound curable by light irradiation, the content of the photocuring initiator (the content of the photoradical generator when the photocuring initiator is a photoradical generator) is: Preferably it is 0.1 weight part or more, More preferably, it is 0.2 weight part or more, Preferably it is 2 weight part or less, More preferably, it is 1 weight part or less. When the content of the photocuring initiator is not less than the above lower limit and not more than the above upper limit, the anisotropic conductive material is appropriately photocured. By irradiating the anisotropic conductive material with light to form a B stage, the flow of the anisotropic conductive material can be suppressed.

  The anisotropic conductive material may contain a different flux from the thermal cation generator. By using the flux, the oxide film formed on the electrode surface can be effectively removed. As a result, the conduction reliability in the connection structure is further increased. Note that the anisotropic conductive material does not necessarily contain a flux.

  The flux is not particularly limited. As the flux, it is possible to use a flux generally used for soldering or the like. 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. Etc. As for the said flux, only 1 type 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 a rosin, and more preferably abietic acid. By using this preferable flux, the connection resistance between the electrodes is further reduced.

  The flux may be dispersed in the binder resin, or may be attached on the surface of the conductive particles.

  In 100% by weight of the anisotropic conductive material, the content of the flux different from the thermal cation generator is preferably 0.5% by weight or more, preferably 30% by weight or less, more preferably 25% by weight or less. When the content of the flux is not less than the above lower limit and not more than the upper limit, the oxide film formed on the electrode surface can be more effectively removed. Further, when the content of the flux is equal to or more than the lower limit, the effect of adding the flux is more effectively expressed. When the content of the flux is not more than the above upper limit, the hygroscopic property of the cured product is further lowered, and the reliability of the connection structure is further enhanced.

  The anisotropic conductive material preferably contains a filler. By using the filler, the thermal expansion coefficient of the cured product of the anisotropic conductive material can be suppressed. Specific examples of the filler include silica, aluminum nitride, alumina, glass, boron nitride, silicon nitride, silicone, carbon, graphite, graphene, and talc. As for a filler, only 1 type may be used and 2 or more types may be used together. When a filler having a high thermal conductivity is used, the main curing time is shortened.

  The anisotropic conductive material may contain a solvent. By using the solvent, the viscosity of the anisotropic conductive material can be easily adjusted. Examples of the solvent include ethyl acetate, methyl cellosolve, toluene, acetone, methyl ethyl ketone, cyclohexane, n-hexane, tetrahydrofuran, and diethyl ether.

  The conductive particles are preferably added to a binder resin and used as an anisotropic conductive material. The anisotropic conductive material is a paste-like or film-like anisotropic conductive material, and is preferably a paste-like anisotropic conductive material. The paste-like anisotropic conductive material is an anisotropic conductive paste. The film-like anisotropic conductive material is an anisotropic conductive film. When the anisotropic conductive material is an anisotropic conductive film, a film containing no conductive particles may be laminated on the anisotropic conductive film containing the conductive particles.

(Connection structure)
A connection structure can be obtained by connecting a connection object member using the said electroconductive particle or using the anisotropic conductive material containing the said electroconductive particle.

  It is preferable that the said electroconductive particle is an electroconductive particle used in order to connect the connection object member which has a copper electrode. The anisotropic conductive material is preferably an anisotropic conductive material used for connecting a connection target member having a copper electrode. An oxide film is easily formed on the surface of the copper electrode. On the other hand, when the anisotropic conductive material contains the thermal cation generator, the oxide film on the surface of the copper electrode can be effectively removed, and the conduction reliability in the connection structure is increased.

  The conductive particles and the anisotropic conductive material can be used for bonding various connection target members. The conductive particles and the anisotropic conductive material are preferably used for obtaining a connection structure in which the first and second connection target members are electrically connected.

  The connection structure connects the first connection target member having the first electrode on the surface, the second connection target member having the second electrode on the surface, and the first and second connection target members. It is preferable that the connection portion is formed of the conductive particles or an anisotropic conductive material containing the conductive particles. It is preferable that the connection portion is formed by curing the anisotropic conductive material. It is preferable that the first electrode and the second electrode are electrically connected by the conductive particles.

  In FIG. 4, the connection structure using the electroconductive particle which concerns on the 1st Embodiment of this invention is typically shown with front sectional drawing.

  A connection structure 51 shown in FIG. 4 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. 4, the conductive particles 1 are schematically shown for convenience of illustration.

  The first connection target member 52 has a plurality of first electrodes 52b on the upper surface 52a. The second connection target member 53 has a plurality of second electrodes 53b on the lower surface 53a. The first electrode 52 b and the second 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. The solder layer 3 of the conductive particles 1 is melted by heating and pressurization, and the first and second electrodes 52 b and 53 b are electrically connected by the conductive particles 1. At this time, the copper layer 7 is preferably brought into contact with the first and second electrodes 52b and 53b. Further, the solder layer 3 is preferably brought into contact with the first and second electrodes 52b and 53b. When the binder resin contains a curable compound that can be cured by heating, 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. 5 is an enlarged front sectional view of a connection portion between the conductive particles 1 and the first and second electrodes 52b and 53b in the connection structure 51 shown in FIG. As shown in FIG. 5, in the connection structure 51, the solder layer 3 of the conductive particles 1 is melted by heating and pressurizing the laminate, and then the melted solder layer portions X are first and second. It is in sufficient contact with the electrodes 52b and 53b. That is, the copper layer 7 and the solder layer 3 can also be brought into contact with the first and second electrodes 52b and 53b. Moreover, the contact resistance between electrodes becomes still lower by making the copper layer 7 contact the 1st, 2nd electrodes 52b and 53b. The copper layer is preferably brought into contact with the electrode, the solder layer is preferably brought into contact with the electrode, and both the copper layer and the solder layer are more preferably brought into contact with the electrode.

  The said 1st, 2nd connection object member is not specifically limited. Specific examples of the first and second connection target members include electronic components such as semiconductor chips, capacitors, and diodes, and electronic components such as circuit boards such as printed boards, flexible printed boards, and glass boards. It is done. The anisotropic conductive material is preferably an anisotropic conductive material used for connecting electronic components. The anisotropic conductive material is preferably in the form of a paste and is applied to the upper surface of the connection target member in a paste state.

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

  The first electrode or the second electrode is preferably a copper electrode. In this case, both the first electrode and the second electrode may be copper electrodes. Both the first electrode and the second electrode are preferably copper electrodes. Even when the conductive particles are used for electrical connection of copper electrodes, electrical connection reliability against thermal shock of the connection structure can be sufficiently enhanced.

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

  In the examples and comparative examples, the following materials were used.

(Binder resin)
Thermosetting compound 1 (epoxy resin, “EXA-4850-150” manufactured by DIC)
Thermosetting compound 2 (epoxy resin, “JER-828” manufactured by Mitsubishi Chemical Corporation)

(Other ingredients)
Thermal cation generator 1 (compound represented by the following formula (11), compound that releases inorganic acid ion containing phosphorus atom by heating)

  Thermal cation generator 2 (compound represented by the following formula (12), compound that releases inorganic acid ion containing antimony atom by heating)

  Thermal cation generator 3 (compound represented by the following formula (13), a compound that releases an organic acid ion containing a boron atom by heating)

(Examples 1 to 12 and Comparative Examples 1 and 2)
Production of conductive particles:
Conductive particles 1: A copper layer (thickness 3 μm) is laminated on the surface of resin particles (average particle diameter 20 μm), and a solder layer (total thickness) containing tin and metal X on the surface of the copper layer 4μm) laminated conductive particles (produced as follows)
Production method of conductive particles 1:
Particles P were prepared in which a copper layer (thickness 3 μm) was laminated on the surface of resin particles (average particle diameter 20 μm).

  Using a theta composer (manufactured by Tokuju Kogakusha Co., Ltd.), while adding nickel powder (average particle size 0.1 μm) on the surface of the copper layer of the particles P, solder fine powder (42 wt% tin and bismuth 58) The first solder layer (thickness 0.5 μm, nickel agglomerate size 100 nm) was formed on the surface of the copper layer. Next, using the theta composer, on the surface of the first solder layer, the solder fine powder (average particle diameter of 3 μm containing 42% by weight of tin and 58% by weight of bismuth) is melted to form the first solder layer. A second solder layer (thickness 3 μm) was formed on the surface of the solder layer. Next, using the theta composer, while adding nickel powder (average particle size 0.1 μm) on the surface of the second solder layer, solder fine powder (42 wt% tin and 58 wt% bismuth) In addition, an average particle diameter of 3 μm was melted to form a third solder layer (thickness 0.5 μm, nickel agglomerate size 100 nm) on the surface of the second solder layer. In the obtained electroconductive particle 1, the 1st solder layer, the 2nd solder layer, and the 3rd solder layer were formed in this order from the inner side of the thickness direction of the solder layer to the outer side.

Details and manufacturing method of conductive particles 2 to 5:
In addition, the presence or absence of the addition of nickel powder when forming the first, second, and third solder layers was changed as shown in Table 1 below, and the contents of bismuth and nickel were shown in Table 1 below. The electroconductive particles 2-5 were obtained like the electroconductive particle 1 except having set as shown. The size of the nickel agglomerates in the obtained conductive particles 2 to 5 was 100 nm.

Details and manufacturing method of conductive particles 6:
Moreover, when forming a solder layer, the electroconductive particle 6 was obtained like the electroconductive particle 1 except having changed nickel powder into cobalt powder (average particle diameter of 0.05 micrometer or less). The size of cobalt agglomerates in the obtained conductive particles 6 was 40 nm.

Details and manufacturing method of conductive particles 7:
Moreover, when forming a solder layer, the electroconductive particle 7 was obtained like the electroconductive particle 1 except having changed nickel powder into iron powder (average particle diameter of 0.5 micrometer or less). The size of the iron agglomerates in the obtained conductive particles 7 was 40 nm.

Conductive particles 8: A copper layer (thickness 1 μm) is laminated on the surface of resin particles (average particle diameter 20 μm), and a solder layer (total thickness 1.5 μm) containing metal X on the surface of the copper layer ) Conductive particles (produced as follows)
Production method of conductive particles 8:
The particles P used for the conductive particles 1 were prepared.

  Using a theta composer (manufactured by Tokuju Kogakusha Co., Ltd.), while adding nickel powder (average particle size 0.1 μm) on the surface of the copper layer of the particles P, solder fine powder (42 wt% tin and bismuth 58) The first solder layer (thickness 0.5 μm, nickel agglomerate size 100 nm) was formed on the surface of the copper layer. Next, using the theta composer, on the surface of the first solder layer, the solder fine powder (average particle diameter of 3 μm containing 42% by weight of tin and 58% by weight of bismuth) is melted to form the first solder layer. A second solder layer (thickness 3.5 μm) was formed on the surface of the solder layer. In the obtained electroconductive particle 8, the 1st solder layer and the 2nd solder layer were formed in this order from the inner side of the thickness direction of the solder layer to the outer side.

Details and manufacturing method of conductive particles 9:
Conductive particles 9 were obtained in the same manner as the conductive particles 8 except that the presence or absence of the addition of nickel powder when forming the solder layer was changed as shown in Table 2 below. The size of nickel agglomerates in the obtained conductive particles 9 was 100 nm.

Conductive particle A: A copper layer (thickness 3 μm) is laminated on the surface of resin particles (average particle diameter 20 μm), and a solder layer containing tin and metal X on the surface of the copper layer (the whole Conductive particles (produced as follows)
Preparation method of conductive particles A:
The particles P used for the conductive particles 1 were prepared.

  Using a theta composer (manufactured by Tokuju Kogakusha Co., Ltd.), fine solder powder (containing 42% by weight of tin and 58% by weight of bismuth and having an average particle diameter of 3 μm) is melted on the surface of the copper layer of the particles P. A first solder layer (thickness 0.5 μm) was formed on the surface of the copper layer. Next, using the theta composer, on the surface of the first solder layer, the solder fine powder (average particle diameter of 3 μm containing 42% by weight of tin and 58% by weight of bismuth) is melted to form the first solder layer. A second solder layer (thickness 3 μm) was formed on the surface of the solder layer. Next, using the theta composer, the fine solder powder (containing 42 wt% tin and 58 wt% bismuth in average particle diameter of 3 μm) is melted on the surface of the second solder layer, A third solder layer (thickness 0.5 μm) was formed on the surface of the solder layer. In the obtained conductive particles A, the first solder layer, the second solder layer, and the third solder layer were formed in this order from the inner side to the outer side in the thickness direction of the solder layer.

Conductive particle B: A nickel layer (thickness 3 μm) is laminated on the surface of resin particles (average particle diameter 20 μm), and a solder layer (total thickness 4 μm) is laminated on the surface of the nickel layer. Conductive particles (made as follows)
Method for producing conductive particle B:
Divinylbenzene resin particles (average particle size 20 μm, “Micropearl SP-220” manufactured by Sekisui Chemical Co., Ltd.) are electroless nickel-plated to form a base copper plating layer (thickness 3 μm) on the surface of the resin particles. Got. The particles Y do not have copper on the surface.

  Using a theta composer (manufactured by Tokuju Kogakusha Co., Ltd.), while adding nickel powder (average particle size 0.1 μm) on the surface of the nickel layer of the obtained particles Y, solder fine powder (42% by weight of tin) The first solder layer (thickness 0.5 μm, nickel agglomerate size 100 nm) was formed on the surface of the nickel layer by melting 58% by weight of bismuth (average particle diameter 3 μm). Next, using the theta composer, on the surface of the first solder layer, the solder fine powder (average particle diameter of 3 μm containing 42% by weight of tin and 58% by weight of bismuth) is melted to form the first solder layer. A second solder layer (thickness 3 μm) was formed on the surface of the solder layer. Next, using the theta composer, the fine solder powder (containing 42 wt% tin and 58 wt% bismuth in average particle diameter of 3 μm) is melted on the surface of the second solder layer, A third solder layer (thickness 0.5 μm) was formed on the surface of the solder layer. In the obtained conductive particles B, the first solder layer, the second solder layer, and the third solder layer were formed in this order from the inner side to the outer side in the thickness direction of the solder layer.

  The details of the conductive particles 1 to 9, A, and B are shown in Tables 1 and 2 below.

  In addition, the size of the agglomerates in the obtained conductive particles 1 to 9 and B was evaluated by observing a cross section using an SEM (scanning electron microscope). The size of the agglomerate means the maximum length.

Production of anisotropic conductive material:
By using the conductive particles immediately after the preparation, the blending components shown in Table 3 below are blended in the blending amounts shown in Table 3 below, and the mixture is stirred for 5 minutes at 2000 rpm using a planetary stirrer. An anisotropic conductive material which is a conductive paste was obtained.

(Evaluation)
(1) Preparation of connection structure The glass epoxy board | substrate (FR-4 board | substrate) which has a copper electrode pattern whose L / S is 200 micrometers / 200 micrometers on the upper surface was prepared. Moreover, the flexible printed circuit board which has a copper electrode pattern with L / S of 200 micrometers / 200 micrometers on the lower surface was prepared.

  After stirring the obtained anisotropic conductive material on the upper surface of the glass epoxy substrate, coating is performed so that the average particle diameter of the conductive particles contained in the anisotropic conductive material is twice the average particle diameter. Then, an anisotropic conductive material layer was formed.

  Next, a flexible printed circuit board was laminated on the upper surface of the anisotropic conductive material layer so that the electrodes face each other. Thereafter, while adjusting the temperature of the head so that the temperature of the anisotropic conductive material layer is 170 ° C., a pressure heating head is placed on the upper surface of the flexible printed circuit board, and a pressure of 1.3 MPa is applied, The conductive material layer was cured at 170 ° C. for 10 seconds to obtain a connection structure.

(2) Conductivity The resistance values at 20 points of the obtained connection structure were evaluated by a four-terminal method. The conductivity was determined according to the following criteria.

[Conductivity criteria]
○: The resistance value is 3Ω or less in all locations. Δ: There are one or more locations where the resistance value exceeds 3Ω. ×: There are one or more locations that are not conducting at all.

(3) Insulating property It was measured with a tester whether or not a leak occurred in 20 adjacent electrodes of the obtained connection structure. Insulation was judged according to the following criteria.

[Insulation criteria]
○: No leak point ×: Leak point

(4) Thermal shock resistance Twenty obtained connection structures were held at −30 ° C. for 5 minutes, then heated to 120 ° C. in 25 minutes, held at 120 ° C. for 5 minutes, and then to −30 ° C. A cooling / heating cycle test was performed in which the process of lowering the temperature in 25 minutes was one cycle. The connection structure was taken out after 500 cycles and 1000 cycles.

  The resistance values at 20 points of the connection structure after the thermal cycle test were evaluated by the four-terminal method. Thermal shock resistance was determined according to the following criteria.

[Criteria for thermal shock resistance]
◯: The resistance value after the thermal cycle test is less than 105% with respect to the resistance value before the thermal cycle test. ○: The resistance value after the thermal cycle test is 105% or more with respect to the resistance value before the thermal cycle test. Less than 110% x: The resistance value after the thermal cycle test is 110% or more with respect to the resistance value before the thermal cycle test, or conduction failure occurs.

  The results are shown in Table 3 below.

DESCRIPTION OF SYMBOLS 1 ... Conductive particle 2 ... Particle 3 ... Solder layer 6 ... Base material particle 7 ... Copper layer 11 ... Conductive particle 12 ... Particle 16 ... Conductive layer 17 ... Copper layer 21 ... Conductive particle 22 ... Particle 51 ... Connection structure 52 ... 1st connection object member 52a ... Upper surface 52b ... 1st electrode 53 ... 2nd connection object member 53a ... Lower surface 53b ... 2nd electrode 54 ... Connection part X ... Molten solder layer part

Claims (13)

Particles having copper on the surface;
Electroconductive particle provided with the solder layer which is arrange | positioned on the surface of copper so that copper may be contacted, and contains tin and the metal which forms a ternary system intermetallic compound with tin and copper.   The conductive particle according to claim 1, wherein the metal is nickel, cobalt, gold, silver, manganese, zinc, palladium, or iron.   The conductive particles according to claim 1, wherein the metal is present on an inner surface of the solder layer, or the metal is present on an outer surface of the solder layer.   The conductive particles according to claim 3, wherein the metal is present on an inner surface of the solder layer.   The conductive particles according to claim 3, wherein the metal is present on an outer surface of the solder layer.   The conductive particles according to claim 3, wherein the metal is present on an inner surface and an outer surface of the solder layer.   The conductive particles according to claim 1, wherein the metal is contained in the solder layer using metal particles.   The electroconductive particle of any one of Claims 1-7 in which the said metal exists in the said solder layer with an agglomerate. The particles having copper on the surface have substrate particles and a copper layer disposed on the surface of the substrate particles,
The electroconductive particle of any one of Claims 1-8 by which the said solder layer is arrange | positioned on the outer surface of the said copper layer so that the said copper layer may be contact | connected.   The electroconductive particle of any one of Claims 1-9 which is an electroconductive particle used for the connection of a copper electrode.   An anisotropic conductive material containing the electroconductive particle of any one of Claims 1-10, and binder resin. A first connection object member having a first electrode;
A second connection object member having a second electrode;
A connecting portion 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 10, or is formed of an anisotropic conductive material including the conductive particles and a binder resin,
A connection structure in which the first electrode and the second electrode are electrically connected by the conductive particles.   The connection structure according to claim 12, wherein the first electrode or the second electrode is a copper electrode.

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