JPWO2018221587A1 - Conductive material and connection structure - Google Patents

Abstract

A conductive material capable of effectively improving the storage stability of the conductive material, effectively increasing the cohesiveness of the solder during conductive connection, and effectively improving the heat resistance of the cured product. provide. The conductive material according to the present invention includes a plurality of conductive particles having solder on the outer surface portion of the conductive portion, a thermosetting compound, and a flux, and has a first configuration “twice the average particle size of the flux. There is no flux having the above particle diameter, or the flux having a particle diameter of twice or more of the average particle diameter of the flux is present in less than 10% of the total number of the flux 100%. " And a second configuration, wherein the composition obtained by removing the conductive particles from the conductive material is a colloid, and the flux exists as colloid particles.

Description

  The present invention relates to a conductive material containing conductive particles having solder on the outer surface of a conductive part. Further, the present invention relates to a connection structure using the conductive material.

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

  The anisotropic conductive material is used to obtain various connection structures. Examples of the connection using the anisotropic conductive material include a connection between a flexible printed board and a glass substrate (FOG (Film on Glass)), a connection between a semiconductor chip and a flexible printed board (COF (Chip on Film)), and a semiconductor. A connection between a chip and a glass substrate (COG (Chip on Glass)), a connection between a flexible printed substrate and a glass epoxy substrate (FOB (Film on Board)), and the like can be given.

  When the electrode of the flexible printed board and the electrode of the glass epoxy board are electrically connected by the anisotropic conductive material, for example, an anisotropic conductive material containing conductive particles is placed on the glass epoxy board. I do. Next, the flexible printed circuit boards are laminated and heated and pressed. Thereby, the anisotropic conductive material is cured, and the electrodes are electrically connected via the conductive particles to obtain a connection structure.

  As an example of the anisotropic conductive material, Patent Literature 1 below discloses an anisotropic conductive material containing conductive particles and a resin component whose curing is not completed at the melting point of the conductive particles. Specific examples of the conductive particles include tin (Sn), indium (In), bismuth (Bi), copper (Cu), zinc (Zn), lead (Pb), cadmium (Cd), and gallium (Ga). ), Silver (Ag) and thallium (Tl), and alloys of these metals.

  In Patent Document 1, a resin heating step of heating an anisotropic conductive material to a temperature higher than the melting point of the conductive particles and at which the curing of the resin component is not completed, and a resin component curing step of curing the resin component And that the electrodes are electrically connected. Further, Patent Document 1 describes that mounting is performed with a temperature profile shown in FIG. 8 of Patent Document 1. In Patent Literature 1, the conductive particles are melted in a resin component whose curing is not completed at a temperature at which the anisotropic conductive material is heated.

  Patent Document 2 below discloses a solder paste (conductive material) containing a flux and an alloy powder containing tin as a main component. The flux is a flux in which an activator is added and dispersed in a solvent. The solvent is a polyhydric alcohol having 2 to 4 hydroxyl groups. The activator is a saccharide having 4 to 6 hydroxyl groups. The average particle size of the activator is 100 μm or less.

  Patent Literature 3 below discloses a solder composition (conductive material) including a lead-free SnZn-based alloy and a soldering flux. The soldering flux contains an epoxy resin and an organic carboxylic acid. The organic carboxylic acid is solidly dispersed in the solder composition at room temperature (25 ° C.).

JP-A-2004-260131 JP 2007-216296 A WO2003 / 002290A1

  In conventional conductive materials as described in Patent Documents 1 to 3, the moving speed of conductive particles or solder particles on an electrode (line) is slow, and solder is efficiently aggregated between upper and lower electrodes to be connected. It can be difficult to do so. As a result, the reliability of conduction between the electrodes and the reliability of insulation tend to be low.

  As a method of efficiently aggregating the solder on the electrode, a method of increasing the amount of the flux in the conductive material and the like can be mentioned.

  However, when the content of the flux in the conductive material is increased, the flux may react with the thermosetting compound in the conductive material, and the storage stability of the conductive material may decrease. Further, when the content of the flux in the conductive material is increased, the heat resistance of the cured product of the conductive material may be reduced.

  In the conventional conductive materials as described in Patent Documents 1 to 3, increasing the storage stability of the conductive material, increasing the cohesiveness of the solder during conductive connection, and increasing the heat resistance of the cured product It is difficult to satisfy all these requirements.

  An object of the present invention is to effectively increase the storage stability of a conductive material, to effectively increase the cohesiveness of solder during conductive connection, and to effectively increase the heat resistance of a cured product. Is to provide a conductive material that can be used. Another object of the present invention is to provide a connection structure using the above conductive material.

  According to a wide aspect of the present invention, it includes a plurality of conductive particles having solder on an outer surface portion of a conductive portion, a thermosetting compound, and a flux, and includes any of the following first and second configurations. There is provided a conductive material comprising at least one of the foregoing.

  First configuration: There is no flux having a particle diameter more than twice the average particle diameter of the flux, or the particle diameter is twice or more the average particle diameter of the flux in 100% of the total number of the flux. Is present in a number of less than 10%.

  Second configuration: the composition obtained by removing the conductive particles from the conductive material is a colloid, and the flux exists as colloid particles.

  In a specific aspect of the conductive material according to the present invention, there is no flux having a particle diameter of 1.5 times or more the average particle diameter of the flux, or the total number of the flux is 100% of the flux. Flux having a particle diameter of 1.5 times or more the average particle diameter is present in a number of less than 20%.

  In a specific aspect of the conductive material according to the present invention, the average particle diameter of the flux is 1 μm or less.

  In a specific aspect of the conductive material according to the present invention, the content of the flux is 1 part by weight or more and 20 parts by weight or less based on 100 parts by weight of the thermosetting compound.

  In a specific aspect of the conductive material according to the present invention, the content of the flux is 0.05% by weight or more and 20% by weight or less in 100% by weight of the conductive material.

  In a specific aspect of the conductive material according to the present invention, the conductive material is a conductive paste.

  According to a broad aspect of the present invention, a first connection target member having a first electrode on a surface, a second connection target member having a second electrode on a surface, the first connection target member, A connection portion connecting the second connection target member, wherein the material of the connection portion is the conductive material described above, and the first electrode and the second electrode are connected to the connection portion. A connection structure is provided that is electrically connected by a solder portion therein.

  In a specific aspect of the connection structure according to the present invention, the first electrode and the second electrode face each other in a stacking direction of the first electrode, the connection portion, and the second electrode. When looking at the portion, the solder portion in the connection portion is arranged in 50% or more of the area of 100% of the facing portion of the first electrode and the second electrode.

  The conductive material according to the present invention includes a plurality of conductive particles having solder on an outer surface portion of the conductive portion, a thermosetting compound, and a flux, and includes any one of the first configuration and the second configuration. Provide one or more. In the conductive material according to the present invention, since the above-described configuration is provided, the storage stability of the conductive material can be effectively improved, and the cohesiveness of solder at the time of conductive connection can be effectively improved, Further, the heat resistance of the cured product can be effectively increased.

FIG. 1 is a cross-sectional view schematically showing a connection structure obtained using a conductive material according to one embodiment of the present invention. FIGS. 2A to 2C are cross-sectional views illustrating each step of an example of a method for manufacturing a connection structure using a conductive material according to an embodiment of the present invention. FIG. 3 is a cross-sectional view showing a modification of the connection structure. FIG. 4 is a cross-sectional view showing a first example of conductive particles that can be used for a conductive material. FIG. 5 is a cross-sectional view showing a second example of conductive particles that can be used for a conductive material. FIG. 6 is a cross-sectional view showing a third example of conductive particles that can be used for a conductive material.

  Hereinafter, details of the present invention will be described.

(Conductive material)
The conductive material according to the present invention includes a plurality of conductive particles having solder on the outer surface of the conductive portion, a thermosetting compound, and a flux. The conductive material according to the present invention has at least one of the following first and second configurations. The conductive material according to the present invention may include only the following first configuration, or may include only the following second configuration, and may include the following first configuration and the following second configuration. Both configurations may be provided.

  First configuration: There is no flux having a particle diameter more than twice the average particle diameter of the flux, or the particle diameter is twice or more the average particle diameter of the flux in 100% of the total number of the flux. Is present in a number of less than 10%

  Second composition: a composition obtained by removing the conductive particles from the conductive material is a colloid, and the flux is present as colloid particles.

  The conductive material according to the present invention may have, as the first configuration, a configuration in which there is no flux having a particle diameter that is twice or more the average particle diameter of the flux (configuration 1a). The conductive material according to the present invention has a configuration in which the flux having a particle diameter of twice or more the average particle diameter of the flux is present in a number of less than 10% in the total number of fluxes of 100% (configuration 1b). ) May be provided.

  The conductive material according to the present invention may have only the first configuration, the first configuration may have only the first configuration, or the second configuration may have only the first configuration. And the second configuration may be provided, and the configuration 1b and the second configuration may be provided.

  In the present invention, since the above configuration is provided, the storage stability of the conductive material can be increased, the cohesion of the solder at the time of conductive connection can be effectively increased, and the heat resistance of the cured product can be further improved. Can be effectively increased.

  In the present invention, since the above configuration is provided, when the electrodes are electrically connected, a plurality of conductive particles can be efficiently arranged on the electrodes (lines) and should be connected. The solder can be efficiently aggregated between the upper and lower electrodes. Further, it is difficult for some of the plurality of conductive particles to be arranged in the region (space) where the electrode is not formed, and the amount of the conductive particle arranged in the region where the electrode is not formed can be considerably reduced. . Therefore, the reliability of conduction between the electrodes can be improved. In addition, electrical connection between horizontally adjacent electrodes that should not be connected can be prevented, and insulation reliability can be improved.

  The flux is mainly mixed in the conductive material to remove oxides present on the surface of the solder and the surface of the electrodes in the conductive particles and to prevent the formation of the oxides. In the present invention, the flux is relatively hard to aggregate and the particle size of the flux is relatively small. Furthermore, in the present invention, the flux is relatively well dispersed. For this reason, in the present invention, even if the content of the flux in the conductive material is relatively small, oxides present on the surface of the solder and the surface of the electrode in the conductive particles can be removed, and the oxidation can be prevented. The formation of an object can be prevented. According to the present invention, even when the content of the flux in the conductive material is relatively small, the cohesiveness of the solder at the time of conductive connection can be effectively increased. In the present invention, the content of the flux in the conductive material can be made relatively small.

  In the case where the flux has the same content, in the case where the flux is present in the present invention, when compared to the case where the flux is not present in the present invention, it is possible to effectively increase the cohesiveness of the solder at the time of conductive connection. Can be.

  In the present invention, the content of the flux in the conductive material does not need to be large, and can be relatively small, so that the reaction between the thermosetting compound and the flux in the conductive material can be effectively suppressed. Can be. As a result, the storage stability of the conductive material can be effectively increased.

  In addition, the melting point (active temperature) of the flux in the conductive material is often lower than the Tg of the thermosetting compound in the conductive material, and as the content of the flux in the conductive material increases, the cured material of the conductive material becomes harder. Heat resistance tends to decrease. In the present invention, the content of the flux in the conductive material does not need to be large and can be made relatively small, so that the heat resistance of the cured material of the conductive material can be effectively improved.

  In the present invention, since the above-mentioned configuration is provided, the storage stability of the conductive material is increased, the cohesiveness of the solder at the time of conductive connection is increased, and the heat resistance of the cured product is increased. All requirements can be satisfied.

  Further, according to the present invention, it is possible to prevent displacement between the electrodes. At the time of conductive connection, the second connection target member is superimposed on the first connection target member having the conductive material disposed on the upper surface. At this time, even when the first connection target member and the second connection target member are overlapped in a state where the electrodes of the first connection target member and the electrodes of the second connection target member are misaligned. According to the present invention, the deviation can be corrected. As a result, the electrode of the first member to be connected and the electrode of the second member to be connected can be connected (self-alignment effect).

  From the viewpoint of further increasing the cohesiveness of the solder, the conductive material is preferably liquid at 25 ° C., and is preferably a conductive paste.

  From the viewpoint of further increasing the cohesiveness of the solder, the viscosity (η25) at 25 ° C. of the conductive material is preferably 20 Pa · s or more, more preferably 30 Pa · s or more, and preferably 500 Pa · s or less. More preferably, it is 300 Pa · s or less. The viscosity (η25) can be appropriately adjusted depending on the types and amounts of the components.

  The viscosity (η25) can be measured, for example, using an E-type viscometer (“TVE22L” manufactured by Toki Sangyo Co., Ltd.) at 25 ° C. and 5 rpm.

  The conductive material can be used as a conductive paste and a conductive film. The conductive paste is preferably an anisotropic conductive paste, and the conductive film is preferably an anisotropic conductive film. From the viewpoint of further increasing the cohesiveness of the solder, the conductive material is preferably a conductive paste. The conductive material is suitably used for electrical connection of electrodes. The conductive material is preferably a circuit connecting material.

  Hereinafter, each component contained in the conductive material will be described. In this specification, “(meth) acryl” means one or both of “acryl” and “methacryl”, and “(meth) acrylate” means one or both of “acrylate” and “methacrylate”. Means

(Conductive particles)
The conductive particles electrically connect the electrodes of the connection target member. The conductive particles have solder on the outer surface of the conductive part. The conductive particles may be solder particles formed by solder. The solder particles have solder on the outer surface of the conductive part. In the solder particles, both the central portion and the outer surface portion of the conductive portion are formed of solder. The solder particles are particles in which both the central portion and the conductive outer surface are solder. The conductive particles may have base particles and a conductive part disposed on the surface of the base particles. In this case, the conductive particles have solder on the outer surface of the conductive part.

  The conductive particles have solder on the outer surface of the conductive part. The base particles may be solder particles formed of solder. The conductive particles may be solder particles in which both the base particles and the outer surface of the conductive portion are solder.

  In addition, compared to the case of using the above solder particles, when using conductive particles including a base particle not formed by solder and a solder portion disposed on the surface of the base particle, It becomes difficult for conductive particles to collect on the electrode. Furthermore, since the solderability between the conductive particles is low, the conductive particles that have moved onto the electrodes tend to move easily outside the electrodes, and the effect of suppressing the displacement between the electrodes tends to decrease. Therefore, the conductive particles are preferably solder particles formed by solder.

  Next, specific examples of the conductive particles will be described with reference to the drawings.

  FIG. 4 is a cross-sectional view showing a first example of conductive particles that can be used for a conductive material.

  The conductive particles 21 shown in FIG. 4 are solder particles. The conductive particles 21 are entirely formed of solder. The conductive particles 21 do not have the base particles in the core and are not core-shell particles. In the conductive particles 21, both the central part and the outer surface part of the conductive part are formed by solder.

  FIG. 5 is a cross-sectional view showing a second example of conductive particles that can be used for a conductive material.

  The conductive particles 31 shown in FIG. 5 include base particles 32 and a conductive part 33 arranged on the surface of the base particles 32. The conductive portion 33 covers the surface of the base particles 32. The conductive particles 31 are coated particles in which the surfaces of the base particles 32 are coated with the conductive portions 33.

  The conductive part 33 has a second conductive part 33A and a solder part 33B (first conductive part). The conductive particles 31 include a second conductive portion 33A between the base particles 32 and the solder portion 33B. Accordingly, the conductive particles 31 include the base particles 32, the second conductive portions 33A disposed on the surface of the base particles 32, and the solder portions 33B disposed on the outer surface of the second conductive portions 33A. And

  FIG. 6 is a cross-sectional view showing a third example of conductive particles that can be used for a conductive material.

  The conductive part 33 of the conductive particle 31 in FIG. 5 has a two-layer structure. The conductive particles 41 shown in FIG. 6 have a solder part 42 as a single-layer conductive part. The conductive particles 41 include the base particles 32 and the solder portions 42 arranged on the surface of the base particles 32.

  Hereinafter, other details of the conductive particles will be described.

(Base particles)
Examples of the base particles include resin particles, inorganic particles excluding metal particles, organic-inorganic hybrid particles, and metal particles. The base particles are preferably base particles excluding metal particles, more preferably resin particles, inorganic particles excluding metal particles, or organic-inorganic hybrid particles. The base particles may be core-shell particles including a core and a shell disposed on a surface of the core. The core may be an organic core, and the shell may be an inorganic shell.

  The base particles are more preferably resin particles or organic-inorganic hybrid particles, and may be resin particles or organic-inorganic hybrid particles. By using these preferred base particles, the effects of the present invention are more effectively exhibited, and conductive particles more suitable for electrical connection between electrodes can be obtained.

  When connecting the electrodes using the conductive particles, the conductive particles are compressed between the electrodes by placing the conductive particles between the electrodes and then pressing the electrodes. When the base particles are resin particles or organic-inorganic hybrid particles, the conductive particles are likely to be deformed at the time of the press bonding, and the contact area between the conductive particles and the electrode is increased. For this reason, the conduction reliability between the electrodes is further improved.

  Various resins are suitably used as the material of the resin particles. Examples of the material of the resin particles include polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene and polybutadiene; acrylic resins such as polymethyl methacrylate and polymethyl acrylate; polyalkylene terephthalate and polycarbonate , Polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polysulfone, polyphenylene oxide, polyacetal, Polyimide, polyamide imide, polyetheretherketone, polyether Terusuruhon, and polymers such as obtained by a variety of polymerizable monomer having an ethylenically unsaturated group is polymerized with one or more thereof.

  Since the resin particles having any compression characteristics suitable for the conductive material can be designed and synthesized, and the hardness of the resin particles can be easily controlled to a suitable range, the material of the resin particles is an ethylenically unsaturated group. Is preferably a polymer obtained by polymerizing one or more polymerizable monomers having a plurality of

  When the resin particles are obtained by polymerizing a polymerizable monomer having an ethylenically unsaturated group, the polymerizable monomer having an ethylenically unsaturated group includes a non-crosslinkable monomer. And a crosslinkable monomer.

  Examples of the non-crosslinkable monomer include styrene-based monomers such as styrene and α-methylstyrene; carboxyl-containing monomers such as (meth) acrylic acid, maleic acid, and maleic anhydride; methyl ( (Meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl ( Alkyl (meth) acrylate compounds such as meth) acrylate and isobornyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, glycerol (meth) acrylate, polyoxyethylene (meth) acrylate, and glycidyl (meth) acrylate (Meth) acrylate compounds containing nitrogen atoms; nitrile-containing monomers such as (meth) acrylonitrile; acid vinyl ester compounds such as vinyl acetate, vinyl butyrate, vinyl laurate and vinyl stearate; ethylene, propylene, isoprene, butadiene, etc. Unsaturated hydrocarbons; and halogen-containing monomers such as trifluoromethyl (meth) acrylate, pentafluoroethyl (meth) acrylate, vinyl chloride, vinyl fluoride, and chlorostyrene.

  Examples of the crosslinkable monomer include tetramethylolmethanetetra (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanedi (meth) acrylate, trimethylolpropanetri (meth) acrylate, and dipentane. Erythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, glycerol tri (meth) acrylate, glycerol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) Polyfunctional (meth) acrylate compounds such as acrylate, (poly) tetramethylene glycol di (meth) acrylate, and 1,4-butanediol di (meth) acrylate; triallyl (iso) cyanu Silane-containing monomers, such as carboxylate, triallyl trimellitate, divinylbenzene, diallyl phthalate, diallyl acrylamide, diallyl ether, γ- (meth) acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, vinyltrimethoxysilane, etc. Is mentioned.

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

  When the base particles are inorganic particles other than metal particles or organic-inorganic hybrid particles, examples of the inorganic material that is a material of the base particles include silica, alumina, barium titanate, zirconia, and carbon black. Preferably, the inorganic material is not a metal. The particles formed of the silica are not particularly limited. For example, after hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups to form crosslinked polymer particles, if necessary, firing may be performed. Particles obtained by performing the method are exemplified. Examples of the organic-inorganic hybrid particles include, for example, organic-inorganic hybrid particles formed of a crosslinked alkoxysilyl polymer and an acrylic resin.

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

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

  Examples of the material for the inorganic shell include the inorganic substances mentioned as the material for the base particles described above. The material of the inorganic shell is preferably silica. The inorganic shell is preferably formed by forming a metal alkoxide into a shell by a sol-gel method on the surface of the core, and then firing the shell. The metal alkoxide is preferably a silane alkoxide. It is preferable that the inorganic shell is formed of a silane alkoxide.

  When the base particles are metal particles, examples of the metal as a material of the metal particles include silver, copper, nickel, silicon, gold, and titanium. However, the base particles are preferably not metal particles.

  The particle diameter of the base particles is preferably 0.5 μm or more, more preferably 1 μm or more, still more preferably 3 μm or more, preferably 100 μm or less, more preferably 60 μm or less, and still more preferably 50 μm or less. When the particle diameter of the base particles is equal to or larger than the lower limit, the contact area between the conductive particles and the electrodes is increased, so that the reliability of conduction between the electrodes is further increased, and the particles are connected via the conductive particles. In addition, the connection resistance between the electrodes can be more effectively reduced. Further, when the conductive portion is formed on the surface of the base material particles, it is difficult to aggregate, and it is difficult to form the aggregated conductive particles. When the particle diameter of the base particles is equal to or less than the upper limit, the conductive particles are easily compressed sufficiently, and the connection resistance between the electrodes connected via the conductive particles can be more effectively reduced. it can.

  It is particularly preferable that the particle diameter of the base particles is 5 μm or more and 40 μm or less. When the particle diameter of the base particles is in the range of 5 μm or more and 40 μm or less, the distance between the electrodes can be reduced, and even if the thickness of the conductive portion is increased, small conductive particles can be obtained. Can be.

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

  The particle diameter of the base particles indicates a number average particle diameter. The particle diameter of the base particles is determined using a particle size distribution measuring device or the like. The particle diameter of the base particles is preferably determined by observing 50 arbitrary base particles with an electron microscope or an optical microscope and calculating an average value. In the case of measuring the particle diameter of the base particles in the conductive particles, the measurement can be performed, for example, as follows.

  A conductive particle inspection embedding resin is prepared by adding and dispersing the conductive particles to “Technobit 4000” manufactured by Kulzer so that the content of the conductive particles becomes 30% by weight. The cross section of the conductive particles is cut out using an ion milling apparatus (“IM4000” manufactured by Hitachi High-Technologies Corporation) so as to pass near the center of the conductive particles dispersed in the resin for inspection. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification was set to 25,000 times, 50 conductive particles were randomly selected, and the base particles of each conductive particle were observed. I do. The particle diameter of the base particles in each conductive particle is measured, and the arithmetic average thereof is used as the particle diameter of the base particles.

(Conductive part)
The method for forming the conductive portion on the surface of the base particles and the method for forming the solder portion on the surface of the base particles or the surface of the second conductive portion are not particularly limited. As a method of forming the conductive portion and the solder portion, for example, 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 method of coating the surface of the base particles with a metal powder or a paste containing the metal powder and a binder. The method of forming the conductive portion and the solder portion is preferably a method using electroless plating, electroplating, or physical collision. Examples of the method by physical vapor deposition include methods such as vacuum vapor deposition, ion plating, and ion sputtering. In the method based on the physical collision, for example, a sheeter composer (manufactured by Tokuju Kosakusho) is used.

  It is preferable that the melting point of the base particles is higher than the melting points of the conductive part and the solder part. The melting point of the base particles is preferably higher than 160 ° C, more preferably higher than 300 ° C, further preferably higher than 400 ° C, particularly preferably higher than 450 ° C. Note that the melting point of the base particles may be lower than 400 ° C. The melting point of the base particles may be 160 ° C. or lower. The softening point of the base particles is preferably 260 ° C. or higher. The softening point of the base particles may be less than 260 ° C.

  The conductive particles may have a single-layer solder portion. The conductive particles may have a plurality of layers of conductive portions (solder portions, second conductive portions). That is, in the conductive particles, two or more conductive portions may be laminated. When the conductive portion has two or more layers, it is preferable that the conductive particles have solder on an outer surface portion of the conductive portion.

  The solder is preferably a metal having a melting point of 450 ° C. or less (a low melting point metal). The solder part is preferably a metal layer having a melting point of 450 ° C. or lower (low-melting metal layer). The low melting point metal layer is a layer containing a low melting point metal. The solder in the conductive particles is preferably metal particles (low-melting metal particles) having a melting point of 450 ° C. or lower. The low melting point metal particles are particles containing a low melting point metal. The low-melting-point metal refers to a metal having a melting point of 450 ° C. or less. The melting point of the low melting point metal is preferably 300 ° C. or lower, more preferably 160 ° C. or lower. The solder in the conductive particles preferably contains tin. In 100% by weight of the metal contained in the solder part and 100% by weight of the metal contained in the solder in the conductive particles, the content of tin is preferably 30% by weight or more, more preferably 40% by weight or more, and still more preferably. Is 70% by weight or more, particularly preferably 90% by weight or more. When the content of tin contained in the solder in the solder portion and the conductive particles is equal to or more than the lower limit, the conduction reliability between the conductive particles and the electrode is further improved.

  The tin content was measured using a high-frequency inductively coupled plasma emission spectrometer ("ICP-AES" manufactured by Horiba, Ltd.) or an X-ray fluorescence analyzer ("EDX-800HS" manufactured by Shimadzu Corporation). Can be measured.

  By using the conductive particles having the solder on the outer surface portion of the conductive portion, the solder is melted and joined to the electrodes, and the solder conducts between the electrodes. For example, since the solder and the electrode are likely to make surface contact, not point contact, the connection resistance is reduced. In addition, the use of conductive particles having solder on the outer surface of the conductive portion increases the bonding strength between the solder and the electrode, so that peeling of the solder and the electrode is more unlikely to occur, and the conduction reliability is effectively improved. Become higher.

  The solder portion and the low-melting metal forming the solder are not particularly limited. The low melting point metal is preferably tin or an alloy containing tin. Examples of the alloy include a tin-silver alloy, a tin-copper alloy, a tin-silver-copper alloy, a tin-bismuth alloy, a tin-zinc alloy, and a tin-indium alloy. The low melting point metal is preferably tin, a tin-silver alloy, a tin-silver-copper alloy, a tin-bismuth alloy, or a tin-indium alloy because of excellent wettability to the electrode. More preferably, they are a tin-bismuth alloy and a tin-indium alloy.

  The material forming the solder (solder portion) is preferably a filler material having a liquidus of 450 ° C. or less based on JIS Z3001: welding terminology. Examples of the composition of the solder include a metal composition containing zinc, gold, silver, lead, copper, tin, bismuth, indium, and the like. Tin-indium (117 ° C eutectic) or tin-bismuth (139 ° C eutectic), which is low melting point and lead-free, is preferable. That is, the solder preferably does not contain lead, and is preferably a solder containing tin and indium, or a solder containing tin and bismuth.

  In order to further increase the bonding strength between the solder and the electrode in the solder portion or the conductive particles, the solder in the conductive particles may be nickel, copper, antimony, aluminum, zinc, iron, gold, titanium, phosphorus, germanium, tellurium. , Cobalt, bismuth, manganese, chromium, molybdenum, palladium and the like. From the viewpoint of further increasing the bonding strength between the solder and the electrode in the solder portion or the conductive particles, the solder in the conductive particles preferably contains nickel, copper, antimony, aluminum, or zinc. From the viewpoint of further increasing the bonding strength between the solder and the electrode in the solder portion or the conductive particles, the content of these metals for increasing the bonding strength is preferably 0% in 100% by weight of the solder in the conductive particles. 0.0001% by weight or more, preferably 1% by weight or less.

  It is preferable that the melting point of the second conductive part is higher than the melting point of the solder part. The melting point of the second conductive portion is preferably higher than 160 ° C, more preferably higher than 300 ° C, still more preferably higher than 400 ° C, still more preferably higher than 450 ° C, particularly preferably higher than 500 ° C, Most preferably above 600 ° C. Since the above-mentioned solder part has a low melting point, it melts at the time of conductive connection. It is preferable that the second conductive portion does not melt at the time of conductive connection. The conductive particles are preferably used by melting solder, preferably used by melting the solder portion, used without melting the solder portion and without melting the second conductive portion. Preferably. Since the melting point of the second conductive part is higher than the melting point of the solder part, only the solder part can be melted without melting the second conductive part at the time of conductive connection.

  The absolute value of the difference between the melting point of the solder part and the melting point of the second conductive part exceeds 0 ° C., preferably 5 ° C. or more, more preferably 10 ° C. or more, still more preferably 30 ° C. or more, and particularly preferably. Is at least 50 ° C, most preferably at least 100 ° C.

  It is preferable that the second conductive portion includes a metal. The metal constituting the second conductive portion is not particularly limited. Examples of the metal include gold, silver, copper, platinum, palladium, zinc, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, cadmium, and alloys thereof. Further, tin-doped indium oxide (ITO) may be used as the metal. One of the above metals may be used alone, or two or more thereof may be used in combination.

  The second conductive portion is preferably a nickel layer, a palladium layer, a copper layer or a gold layer, more preferably a nickel layer, a gold layer or a copper layer, and further preferably a copper layer. The conductive particles preferably have a nickel layer, a palladium layer, a copper layer or a gold layer, more preferably have a nickel layer, a gold layer or a copper layer, and further preferably have a copper layer. By using the conductive particles having these preferable conductive portions for the connection between the electrodes, the connection resistance between the electrodes is further reduced. Further, a solder portion can be more easily formed on the surface of these preferable conductive portions.

  The thickness of the solder part is preferably 0.005 μm or more, more preferably 0.01 μm or more, preferably 10 μm or less, more preferably 1 μm or less, and still more preferably 0.3 μm or less. When the thickness of the solder portion is equal to or more than the lower limit and equal to or less than the upper limit, sufficient conductivity is obtained, and the conductive particles do not become too hard, and the conductive particles are sufficiently deformed at the time of connection between the electrodes. I do.

  The particle size of the conductive particles is preferably 0.5 μm or more, more preferably 1 μm or more, still more preferably 3 μm or more, preferably 100 μm or less, more preferably 60 μm or less, further preferably 50 μm or less, particularly preferably. It is 40 μm or less. When the particle diameter of the conductive particles is equal to or more than the lower limit and equal to or less than the upper limit, the solder in the conductive particles can be more efficiently arranged on the electrodes, and the amount of the solder in the conductive particles between the electrodes is increased. The arrangement is easy, and the conduction reliability is further improved.

  The particle size of the conductive particles is preferably an average particle size, and more preferably a number average particle size. The average particle size of the conductive particles can be determined, for example, by observing 50 arbitrary conductive particles with an electron microscope or an optical microscope, calculating an average value, or performing a laser diffraction particle size distribution measurement.

  The CV value of the particle size of the conductive particles is preferably 5% or more, more preferably 10% or more, preferably 40% or less, more preferably 30% or less. When the CV value of the particle diameter is equal to or more than the lower limit and equal to or less than the upper limit, the solder can be more efficiently arranged on the electrode. However, the CV value of the particle size of the conductive particles may be less than 5%.

  The CV value (coefficient of variation) of the particle diameter of the conductive particles can be measured as follows.

CV value (%) = (ρ / Dn) × 100
ρ: Standard deviation of particle size of conductive particles Dn: Average value of particle size of conductive particles

  The shape of the conductive particles is not particularly limited. The shape of the conductive particles may be spherical, or may be other than spherical, such as flat.

  In 100% by weight of the conductive material, the content of the conductive particles is preferably 1% by weight or more, more preferably 2% by weight or more, further preferably 10% by weight or more, particularly preferably 20% by weight or more, and most preferably. Is 30% by weight or more, preferably 95% by weight or less, more preferably 90% by weight or less, and further preferably 85% by weight or less. In 100% by weight of the conductive material, the content of the conductive particles may be less than 80% by weight. When the content of the conductive particles is equal to or more than the lower limit and equal to or less than the upper limit, the solder in the conductive particles can be more efficiently arranged on the electrodes, and the amount of the solder in the conductive particles between the electrodes is increased. The arrangement is easy, and the conduction reliability is further improved. From the viewpoint of further improving conduction reliability, it is preferable that the content of the conductive particles is large.

(Thermosetting compound)
The conductive material according to the present invention contains a thermosetting compound. The thermosetting compound is a compound that can be cured by heating. Examples of the thermosetting compound include oxetane compounds, epoxy compounds, episulfide compounds, (meth) acrylic compounds, phenol compounds, amino compounds, unsaturated polyester compounds, polyurethane compounds, silicone compounds, and polyimide compounds. From the viewpoint of further improving the curability and viscosity of the conductive material and further enhancing the conduction reliability, an epoxy compound or an episulfide compound is preferable, and an epoxy compound is more preferable. The conductive material preferably contains an epoxy compound. Only one kind of the thermosetting compound may be used, or two or more kinds thereof may be used in combination.

  As the epoxy compound, an aromatic epoxy compound such as a resorcinol type epoxy compound, a naphthalene type epoxy compound, a biphenyl type epoxy compound, a benzophenone type epoxy compound, and a phenol novolak type epoxy compound is preferable. The melting temperature of the epoxy compound is preferably equal to or lower than the melting point of the solder. The melting temperature of the epoxy compound is preferably 100 ° C. or lower, more preferably 80 ° C. or lower, and further preferably 40 ° C. or lower. By using the above-mentioned preferred epoxy compound, at the stage where the members to be connected are bonded, the first member to be connected is connected to the second member to be connected when acceleration is applied by impact such as conveyance. The displacement with respect to the member can be suppressed. Further, the viscosity at the time of curing can greatly reduce the viscosity, and the aggregation of the solder in the conductive particles can be efficiently advanced.

  The content of the thermosetting compound in 100% by weight of the conductive material is preferably 5% by weight or more, more preferably 8% by weight or more, further preferably 10% by weight or more, and preferably 60% by weight or less. It is more preferably at most 55% by weight, further preferably at most 50% by weight, particularly preferably at most 40% by weight. When the content of the thermosetting compound is equal to or more than the lower limit and equal to or less than the upper limit, the solder in the conductive particles is more efficiently arranged on the electrodes, and the displacement between the electrodes is further suppressed. Can be further improved in the conduction reliability.

(Thermosetting agent)
The conductive material preferably contains a thermosetting agent. The conductive material preferably contains a thermosetting agent together with the thermosetting compound. The thermosetting agent thermosets the thermosetting compound. Examples of the thermal curing agent include an imidazole curing agent, a phenol curing agent, a thiol curing agent, an amine curing agent, an acid anhydride curing agent, a thermal cationic curing agent, and a thermal radical generator. The thermosetting agent may be used alone or in combination of two or more.

  From the viewpoint that the conductive material can be more rapidly cured at a low temperature, the thermal curing agent is preferably an imidazole curing agent, a thiol curing agent, or an amine curing agent. Further, from the viewpoint of increasing the storage stability when the thermosetting compound and the thermosetting agent are mixed, it is preferable that the thermosetting agent is a latent curing agent. Preferably, the latent curing agent is a latent imidazole curing agent, a latent thiol curing agent, or a latent amine curing agent. Note that the thermosetting agent may be coated with a polymer material such as a polyurethane resin or a polyester resin.

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

  The thiol curing agent is not particularly limited. Examples of the thiol curing agent include trimethylolpropane tris-3-mercaptopropionate, pentaerythritol tetrakis-3-mercaptopropionate, and dipentaerythritol hexa-3-mercaptopropionate.

  The amine curing agent is not particularly limited. Examples of the amine curing agent include boron trifluoride-amine complex, hexamethylene diamine, octamethylene diamine, decamethylene diamine, 3,9-bis (3-aminopropyl) -2,4,8,10-tetraspiro [5] .5] undecane, bis (4-aminocyclohexyl) methane, metaphenylenediamine, diaminodiphenylsulfone and the like.

  The thermal cationic curing agent is not particularly limited. Examples of the thermal cationic curing agent include an iodonium-based cationic curing agent, an oxonium-based cationic curing agent, and a sulfonium-based cationic curing agent. Examples of the iodonium-based cationic curing agent include bis (4-tert-butylphenyl) iodonium hexafluorophosphate. Examples of the oxonium-based cationic curing agent include trimethyloxonium tetrafluoroborate. Examples of the sulfonium-based cationic curing agent include tri-p-tolylsulfonium hexafluorophosphate.

  The thermal radical generator is not particularly limited. Examples of the thermal radical generator include an azo compound and an organic peroxide. Examples of the azo compound include azobisisobutyronitrile (AIBN). Examples of the organic peroxide include di-tert-butyl peroxide and methyl ethyl ketone peroxide.

  The reaction initiation temperature of the thermosetting agent is preferably 50 ° C. or higher, more preferably 60 ° C. or higher, even more preferably 70 ° C. or higher, preferably 250 ° C. or lower, more preferably 200 ° C. or lower, and further more preferably 190 ° C. The temperature is particularly preferably 180 ° C. or lower. When the reaction start temperature of the thermosetting agent is equal to or higher than the lower limit and equal to or lower than the upper limit, the solder is more efficiently arranged on the electrode.

  The content of the thermosetting agent is not particularly limited. The content of the thermosetting agent is preferably at least 0.01 part by weight, more preferably at least 1 part by weight, preferably at most 200 parts by weight, more preferably at most 200 parts by weight, based on 100 parts by weight of the thermosetting compound. 100 parts by weight or less, more preferably 75 parts by weight or less. When the content of the thermosetting agent is at least the lower limit, it is easy to sufficiently cure the thermosetting compound. When the content of the thermosetting agent is equal to or less than the upper limit, the surplus thermosetting agent not involved in the curing after the curing hardly remains, and the heat resistance of the cured product is further increased.

(flux)
The conductive material according to the present invention includes a flux. The conductive material according to the present invention may preferably have a configuration in which there is no flux having a particle diameter twice or more the average particle diameter of the flux (configuration 1a). Preferably, the conductive material according to the present invention has a configuration in which, among 100% of the total number of the fluxes, a flux having a particle diameter of twice or more the average particle diameter of the flux is present in a number of less than 10% (No. 1b). The conductive material according to the present invention preferably has a configuration (second configuration) in which the composition obtained by removing the conductive particles from the conductive material is a colloid, and the flux exists as colloid particles.

  In the case where the conductive material has the configuration of the above 1a, it is preferable that there is no flux having a particle diameter of 1.8 times or more the average particle diameter of the flux, and 1.5 times the average particle diameter of the flux. More preferably, there is no flux having the above particle diameter. When the average particle diameter of the flux satisfies the above preferable conditions, the storage stability can be further improved, the cohesiveness of the solder can be further increased, and the heat resistance of the cured product can be further increased. be able to.

  In the case where the conductive material has the configuration of the first b, the flux having a particle diameter of twice or more of the average particle diameter of the flux is present in the number of 8% or less in the total number of the flux of 100%. Is preferred. More preferably, 6% or less of the flux having a particle diameter twice or more the average particle diameter of the flux is present in 100% of the total number of the flux. When the ratio of the number of fluxes having a particle diameter of twice or more the average particle diameter of the flux is not more than the upper limit, the storage stability can be further improved, and the cohesiveness of the solder can be further improved. And the heat resistance of the cured product can be further enhanced.

  There is no flux having a particle diameter of 1.5 times or more the average particle diameter of the flux, or a particle diameter of 1.5 times or more the average particle diameter of the flux in 100% of the total number of the flux. Preferably, the fluxes present are present in less than 20%. It is preferable that the flux having a particle diameter of 1.5 times or more of the average particle diameter of the flux is present in less than 20% of the total number of the flux of 100%. It is more preferable that the flux having a particle diameter of 1.5 times or more of the average particle diameter of the flux is present in a number of 10% or less in 100% of the total number of the flux. More preferably, 5% or less of the flux having a particle diameter of 1.5 times or more the average particle diameter of the flux is present in 100% of the total number of the flux. When the ratio of the number of fluxes having a particle diameter of 1.5 times or more of the average particle diameter of the flux is less than the upper limit and equal to or less than the upper limit, the storage stability can be further improved, and the cohesiveness of the solder can be improved. Can be further increased, and the heat resistance of the cured product can be further increased.

  From the viewpoint of more effectively increasing the storage stability, the viewpoint of more effectively increasing the cohesiveness of the solder, and the viewpoint of more effectively increasing the heat resistance of the cured product, the average particle diameter of the flux is as follows: Preferably it is 1 μm or less, more preferably less than 1 μm, even more preferably 0.8 μm or less. The lower limit of the average particle diameter of the flux is not particularly limited. The average particle diameter of the flux may be 0.1 μm or more.

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

  The average particle diameter of the flux indicates a number average particle diameter. The particle size of the flux is preferably determined by observing 50 arbitrary fluxes with an electron microscope and calculating an average value.

  From the viewpoint of further improving the storage stability more effectively, the viewpoint of more effectively increasing the cohesiveness of the solder, and the viewpoint of more effectively increasing the heat resistance of the cured product, the CV value of the particle diameter of the flux is considered. (Coefficient of variation) is preferably 40% or less, more preferably 20% or less. The lower limit of the CV value of the particle size of the flux is not particularly limited. The CV value of the particle diameter of the flux may be 0.01% or more.

  The CV value (coefficient of variation) of the particle diameter of the flux can be measured as follows.

CV value (%) = (ρ / Dn) × 100
ρ: Standard deviation of particle diameter of flux Dn: Average value of particle diameter of flux

  The shape of the flux is not particularly limited. The shape of the flux may be spherical, and may be a shape other than spherical, such as flat.

  In the case where the conductive material has the second configuration, the composition obtained by removing the conductive particles from the conductive material is a colloid. From the viewpoint of more effectively increasing the storage stability, the viewpoint of more effectively increasing the cohesiveness of the solder, and the viewpoint of more effectively increasing the heat resistance of the cured product, the composition is a composition Preferably, the whole is a colloid. The composition only needs to include a portion that is a colloid, and the entire composition does not have to be a colloid.

  In the case where the conductive material has the second configuration, the flux exists as colloid particles. From the viewpoint of more effectively improving the storage stability, the viewpoint of more effectively increasing the cohesiveness of the solder, and the viewpoint of more effectively improving the heat resistance of the cured product, the flux is a colloidal particle. The flux is more preferably colloidal particles having the above-mentioned average particle size in the composition. From the viewpoint of more effectively increasing the storage stability, the viewpoint of more effectively increasing the cohesiveness of the solder, and the viewpoint of more effectively increasing the heat resistance of the cured product, the flux is in the composition Preferably, the flux is dispersed, and more preferably, the flux is uniformly dispersed in the composition. In the conductive material, it is preferable that 20% or more of the total number of fluxes is colloid particles. In the conductive material, a part of the flux may be a colloid particle, and not all the flux may be a colloid particle.

  As a method of confirming that the composition is a colloid, there is a method of observing the Tyndall phenomenon using the composition or a mixture of the composition and a solvent in which the flux is not dissolved.

  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 rosin. And the like. Only one type of the above flux may be used, or two or more types may be used in combination.

  Examples of the molten salt include ammonium chloride. Examples of the organic acids include lactic acid, citric acid, stearic acid, glutamic acid, malic acid, and glutaric acid. Examples of the rosin include activated rosin and non-activated rosin. The flux is preferably an organic acid having two or more carboxyl groups or rosin. The flux may be an organic acid having two or more carboxyl groups or rosin. By using an organic acid or rosin having two or more carboxyl groups, the reliability of conduction between the electrodes is further improved.

  The rosin is a rosin containing abietic acid as a main component. The flux is preferably a rosin, and more preferably abietic acid. Use of this preferred flux further enhances the reliability of conduction between the electrodes.

  The melting point (activation temperature) of the flux is preferably 50 ° C. or higher, more preferably 70 ° C. or higher, even more preferably 80 ° C. or higher, preferably 200 ° C. or lower, more preferably 190 ° C. or lower, and even more preferably 160 ° C. or lower. C. or lower, more preferably 150.degree. C. or lower, and even more preferably 140.degree. C. or lower. When the melting point (activation temperature) of the flux is equal to or higher than the lower limit and equal to or lower than the upper limit, the flux effect is more effectively exhibited, and the solder in the conductive particles is more efficiently arranged on the electrode. It is preferable that the melting point (activation temperature) of the flux is 60 ° C. or more and 190 ° C. or less. The melting point (activation temperature) of the flux is particularly preferably from 80 ° C to 140 ° C.

  Examples of the flux having an activation temperature (melting point) of the flux of 60 ° C. or more and 190 ° C. or less include succinic acid (melting point: 186 ° C.), glutaric acid (melting point: 96 ° C.), adipic acid (melting point: 152 ° C.), pimelic acid (melting point: 104 ° C.) C), dicarboxylic acids such as suberic acid (melting point 142 ° C.), benzoic acid (melting point 122 ° C.), and malic acid (melting point 130 ° C.).

  Further, the boiling point of the flux is preferably 200 ° C. or less.

  The flux is preferably a flux that releases cations when heated. By using a flux that releases cations upon heating, the solder in the conductive particles can be more efficiently placed on the electrodes.

  Examples of the flux that releases cations by heating include the above-mentioned thermal cation curing agents.

  More preferably, the flux is a salt of an acid compound and a base compound. The acid compound preferably has an effect of cleaning the surface of the metal, and the base compound preferably has an action of neutralizing the acid compound. The flux is preferably a neutralized reaction product of the acid compound and the base compound. The flux may be used alone or in combination of two or more.

  From the viewpoint of more efficiently disposing the solder in the conductive particles on the electrode, the melting point of the flux is preferably lower than the melting point of the solder in the conductive particles, and more preferably 5 ° C. or more. More preferably, the temperature is lower by 10 ° C. or more. However, the melting point of the flux may be higher than the melting point of the solder in the conductive particles. Usually, the operating temperature of the conductive material is equal to or higher than the melting point of the solder in the conductive particles, and if the melting point of the flux is equal to or lower than the operating temperature of the conductive material, the melting point of the flux is equal to the melting point of the solder in the conductive particles. Even if it is higher, the above-mentioned flux can sufficiently exhibit the performance as a flux. For example, in a conductive material in which the use temperature of the conductive material is 150 ° C. or more, and the solder (Sn42Bi58: melting point 139 ° C.) in the conductive particles and the flux (melting point 146 ° C.) which is a salt of malic acid and benzylamine The flux which is a salt of malic acid and benzylamine exhibits a sufficient flux action.

  From the viewpoint of more efficiently disposing the solder in the conductive particles on the electrode, the melting point of the flux is preferably lower than the reaction start temperature of the thermosetting agent, more preferably 5 ° C. or more, More preferably, the temperature is lower by 10 ° C. or more.

  The acid compound is preferably an organic compound having a carboxyl group. Examples of the acid compound include malonic acid, which is an aliphatic carboxylic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, citric acid, malic acid, and cycloaliphatic carboxylic acid. Examples thereof include cyclohexylcarboxylic acid, 1,4-cyclohexyldicarboxylic acid, and aromatic carboxylic acids such as isophthalic acid, terephthalic acid, trimellitic acid, and ethylenediaminetetraacetic acid. The acid compound is preferably glutaric acid, azelaic acid, or malic acid.

  The base compound is preferably an organic compound having an amino group. Examples of the base compound include diethanolamine, triethanolamine, methyldiethanolamine, ethyldiethanolamine, cyclohexylamine, dicyclohexylamine, benzylamine, benzhydrylamine, 2-methylbenzylamine, 3-methylbenzylamine, and 4-tert-butylbenzylamine. , N-methylbenzylamine, N-ethylbenzylamine, N-phenylbenzylamine, N-tert-butylbenzylamine, N-isopropylbenzylamine, N, N-dimethylbenzylamine, imidazole compounds, and triazole compounds. . The base compound is preferably benzylamine, 2-methylbenzylamine, or 3-methylbenzylamine.

  The flux may be dispersed in a conductive material or may adhere to the surface of the conductive particles. From the viewpoint of more effectively increasing the flux effect, it is preferable that the flux adheres to the surface of the conductive particles.

  The flux that satisfies the first configuration, the first configuration, and the second configuration can be obtained, for example, by melting a solid flux and then reprecipitating it. It is preferred that the reprecipitation proceed gently. The method for obtaining the flux is preferably a method in which the solid flux is heated to a temperature equal to or higher than the melting point to completely melt the flux. The method of obtaining the flux is preferably a method of gradually re-precipitating the molten flux. According to the above method, a uniform flux having the above average particle diameter can be easily obtained.

  As another method of obtaining a flux having a relatively small average particle diameter, for example, a method of pulverizing a solid flux can be mentioned. However, in the method of pulverizing a solid flux, there is a limit in reducing the average particle diameter of the flux, and it is difficult to obtain a flux having the above-described average particle diameter. Furthermore, after the flux is pulverized, the fluxes tend to aggregate with each other, resulting in an uneven flux. It is difficult to uniformly disperse a non-uniform flux (pulverized flux) in a conductive material, and when a non-uniform flux is used, the content of the flux in the conductive material is increased in order to enhance the cohesiveness of the solder. The amount is likely to be relatively large. As a result, the storage stability of the conductive material is reduced, and the heat resistance of the cured product of the conductive material is reduced, making it difficult to obtain the effects of the present invention. For this reason, the flux is preferably obtained by a method other than the method of pulverizing the solid flux, and is preferably obtained by melting a solid flux having a relatively low reprecipitation rate and then reprecipitating it.

  From the viewpoint of more effectively increasing the storage stability, more effectively increasing the cohesiveness of the solder, and from the viewpoint of more effectively increasing the heat resistance of the cured product, 100 parts by weight of the thermosetting compound On the other hand, the content of the flux is preferably at least 1 part by weight, more preferably at least 2 parts by weight, preferably at most 20 parts by weight, more preferably at most 15 parts by weight.

  From the viewpoint of more effectively improving the storage stability, the viewpoint of more effectively increasing the cohesiveness of the solder, and the viewpoint of more effectively improving the heat resistance of the cured product, 100% by weight of the conductive material The content of the flux is preferably 0.05% by weight or more, more preferably 2% by weight or more, preferably 20% by weight or less, more preferably 15% by weight or less. Further, when the content of the flux is not less than the lower limit and not more than the upper limit, an oxide film is more difficult to be formed on the surfaces of the solder and the electrode in the conductive particles, and further, the solder and the electrode in the conductive particles The oxide film formed on the surface can be more effectively removed.

(Filler)
A filler may be added to the conductive material. The filler may be an organic filler or an inorganic filler. By adding the filler, the conductive particles can be uniformly aggregated on all the electrodes of the substrate.

  It is preferable that the conductive material does not contain the filler or contains the filler at 5% by weight or less. When a crystalline thermosetting compound is used, the lower the filler content, the easier the solder moves on the electrode.

  In 100% by weight of the conductive material, the content of the filler is preferably 0% by weight (not included) or more, preferably 5% by weight or less, more preferably 2% by weight or less, and further more preferably 1% by weight or less. It is. When the content of the filler is equal to or more than the lower limit and equal to or less than the upper limit, the conductive particles are more efficiently arranged on the electrode.

(Other ingredients)
The conductive material may be, if necessary, for example, a filler, a bulking agent, a softener, a plasticizer, a polymerization catalyst, a curing catalyst, a coloring agent, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, and a lubricant. And various additives such as an antistatic agent and a flame retardant.

(Connection structure)
The connection structure according to the present invention includes a first connection target member having a first electrode on the surface, a second connection target member having a second electrode on the surface, the first connection target member, A connection portion connecting the second connection target member. In the connection structure according to the present invention, the material of the connection portion is the above-described conductive material. In the connection structure according to the present invention, the connection portion is a cured product of the above-described conductive material. In the connection structure according to the present invention, the connection portion is formed of the above-described conductive material. In the connection structure according to the present invention, the first electrode and the second electrode are electrically connected by a solder part in the connection part.

  In the connection structure according to the present invention, since the specific conductive material is used, the solder in the conductive particles easily collects between the first electrode and the second electrode, and the solder is efficiently placed on the electrodes (lines). It can be arranged in a way. Further, it is difficult for a part of the solder to be arranged in the region (space) where the electrode is not formed, and the amount of the solder arranged in the region where the electrode is not formed can be considerably reduced. Therefore, conduction reliability between the first electrode and the second electrode can be improved. In addition, electrical connection between horizontally adjacent electrodes that should not be connected can be prevented, and insulation reliability can be improved.

  Further, in order to efficiently arrange the solder in the conductive particles on the electrodes, and to considerably reduce the amount of solder arranged in the region where the electrodes are not formed, the conductive material is not a conductive film, but a conductive film. It is preferable to use a conductive paste.

  The thickness of the solder portion between the electrodes is preferably 10 μm or more, more preferably 20 μm or more, preferably 100 μm or less, more preferably 80 μm or less. The solder wet area on the surface of the electrode (the area where the solder is in contact with 100% of the exposed area of the electrode) is preferably 50% or more, more preferably 60% or more, and still more preferably 70% or more, and preferably 70% or more. Is 100% or less.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view schematically showing a connection structure obtained using a conductive material according to one embodiment of the present invention.

  The connection structure 1 shown in FIG. 1 includes a first connection target member 2, a second connection target member 3, and a connection connecting the first connection target member 2 and the second connection target member 3. Unit 4. The connection part 4 is formed of the above-described conductive material. In the present embodiment, the conductive material includes conductive particles, a thermosetting compound, and a flux. In the present embodiment, the conductive particles include solder particles. The thermosetting compound, the thermosetting agent, and the flux are referred to as thermosetting components.

  The connection portion 4 has a solder portion 4A in which a plurality of solder particles are gathered and joined to each other, and a cured material portion 4B in which a thermosetting component is thermoset.

  The first connection target member 2 has a plurality of first electrodes 2a on the surface (upper surface). The second connection target member 3 has a plurality of second electrodes 3a on the surface (lower surface). The first electrode 2a and the second electrode 3a are electrically connected by the solder 4A. Therefore, the first connection target member 2 and the second connection target member 3 are electrically connected by the solder portion 4A. In the connection portion 4, no solder exists in a region (cured material portion 4B portion) different from the solder portion 4A gathered between the first electrode 2a and the second electrode 3a. In a region different from the solder portion 4A (cured material portion 4B portion), there is no solder separated from the solder portion 4A. If the amount is small, the solder may be present in a region (cured material portion 4B portion) different from the solder portion 4A gathered between the first electrode 2a and the second electrode 3a.

  As shown in FIG. 1, in the connection structure 1, a plurality of solder particles gather between the first electrode 2a and the second electrode 3a, and after the plurality of solder particles have melted, Solidifies after the electrode surface wets and spreads to form the solder portion 4A. Therefore, the connection area between the solder portion 4A and the first electrode 2a and the connection area between the solder portion 4A and the second electrode 3a are increased. That is, by using the solder particles, the solder portion 4A, the first electrode 2a, and the solder are compared with the case where the outer surface portion of the conductive portion is made of conductive particles of a metal such as nickel, gold, or copper. The contact area between the portion 4A and the second electrode 3a increases. For this reason, conduction reliability and connection reliability in the connection structure 1 are improved. Note that, generally, the flux contained in the conductive material is gradually deactivated by heating.

  In the connection structure 1 shown in FIG. 1, all of the solder portions 4A are located in areas facing each other between the first and second electrodes 2a and 3a. The connection structure 1X of the modification shown in FIG. 3 differs from the connection structure 1 shown in FIG. 1 only in the connection portion 4X. The connection part 4X has a solder part 4XA and a cured material part 4XB. Like the connection structure 1X, most of the solder portions 4XA are located in regions where the first and second electrodes 2a and 3a face each other, and a part of the solder portion 4XA is formed in the first and second electrodes. The electrodes 2a and 3a may protrude laterally from the facing regions. The solder portion 4XA protruding laterally from the region where the first and second electrodes 2a and 3a face each other is a part of the solder portion 4XA and is not a solder separated from the solder portion 4XA. In the present embodiment, the amount of the solder separated from the solder portion can be reduced, but the solder separated from the solder portion may be present in the cured product portion.

  If the usage amount of the solder particles is reduced, it becomes easier to obtain the connection structure 1. Increasing the amount of the solder particles facilitates obtaining the connection structure 1X.

  A portion where the first electrode and the second electrode face each other in the stacking direction of the first electrode, the connection portion, and the second electrode is viewed. In this case, from the viewpoint of further improving conduction reliability, 50% or more (more preferably 60% or more, more preferably 60% or more) of the area of 100% of the opposing portion between the first electrode and the second electrode. Preferably, the solder portion in the connection portion is arranged at 70% or more, particularly preferably 80% or more, and most preferably 90% or more.

  Next, an example of a method for manufacturing the connection structure 1 using the conductive material according to one embodiment of the present invention will be described.

  First, the first connection target member 2 having the first electrode 2a on the surface (upper surface) is prepared. Next, as shown in FIG. 2A, a conductive material 11 including a thermosetting component 11B and a plurality of solder particles 11A is disposed on the surface of the first connection target member 2 (first). Process). The conductive material 11 includes a thermosetting compound, a thermosetting agent, and a flux as the thermosetting component 11B.

  The conductive material 11 is disposed on the surface of the first connection target member 2 on which the first electrode 2a is provided. After disposing the conductive material 11, the solder particles 11A are disposed both on the first electrode 2a (line) and on a region (space) where the first electrode 2a is not formed.

  The method for arranging the conductive material 11 is not particularly limited, and examples thereof include application using a dispenser, screen printing, and ejection using an inkjet device.

  Also, a second connection target member 3 having the second electrode 3a on the surface (lower surface) is prepared. Next, as shown in FIG. 2B, in the conductive material 11 on the surface of the first connection target member 2, on the surface of the conductive material 11 opposite to the first connection target member 2 side, The second connection target member 3 is arranged (second step). The second connection target member 3 is arranged on the surface of the conductive material 11 from the second electrode 3a side. At this time, the first electrode 2a and the second electrode 3a face each other.

  Next, the conductive material 11 is heated above the melting point of the solder particles 11A (third step). Preferably, the conductive material 11 is heated above the curing temperature of the thermosetting component 11B (thermosetting compound). At the time of this heating, the solder particles 11A existing in the region where no electrode is formed gather between the first electrode 2a and the second electrode 3a (self-aggregation effect). When the conductive paste is used instead of the conductive film, the solder particles 11A more effectively gather between the first electrode 2a and the second electrode 3a. Further, the solder particles 11A are melted and joined to each other. The thermosetting component 11B is thermoset. As a result, as shown in FIG. 2C, the connection portion 4 connecting the first connection target member 2 and the second connection target member 3 is formed of the conductive material 11. The connection portion 4 is formed by the conductive material 11, the solder portion 4A is formed by joining the plurality of solder particles 11A, and the cured product portion 4B is formed by thermosetting the thermosetting component 11B. If the solder particles 11A move sufficiently, the movement of the solder particles 11A not located between the first electrode 2a and the second electrode 3a starts, and then the first electrode 2a and the second electrode 2a move. The temperature does not need to be kept constant until the movement of the solder particles 11A between the solder particles 3a and 3a is completed.

  In the present embodiment, it is preferable not to apply pressure in the second step and the third step. In this case, the weight of the second connection target member 3 is added to the conductive material 11. For this reason, when the connection part 4 is formed, the solder particles 11A gather more effectively between the first electrode 2a and the second electrode 3a. If pressure is applied in at least one of the second step and the third step, the action of the solder particles 11A trying to gather between the first electrode 2a and the second electrode 3a. Tend to be inhibited.

  When the second connection target member is superimposed on the first connection target member coated with the conductive material, the alignment between the electrode of the first connection target member and the electrode of the second connection target member is shifted. Thus, the first connection target member and the second connection target member may be overlapped. In the present embodiment, since no pressure is applied, the deviation can be corrected and the electrode of the first connection target member and the electrode of the second connection target member can be connected (self-alignment effect). This is because the molten solder that has self-agglomerated between the electrode of the first member to be connected and the electrode of the second member to be connected is formed between the electrode of the first member to be connected and the second member to be connected. This is because the smaller the area where the solder between the electrode and the other components of the conductive material is in contact, the more stable the energy. This is because a force acts on a connection structure having an alignment, which is the connection structure having the minimum area. At this time, it is desirable that the conductive material is not cured and that the viscosity of the components other than the conductive particles of the conductive material is sufficiently low at the temperature and time.

  The viscosity of the conductive material at the melting point of the solder is preferably 50 Pa · s or less, more preferably 10 Pa · s or less, further preferably 1 Pa · s or less, preferably 0.1 Pa · s or more, and more preferably 0.1 Pa · s or more. 2 Pa · s or more. When the viscosity is equal to or less than the upper limit, the solder in the conductive particles can be efficiently aggregated. When the viscosity is equal to or higher than the lower limit, voids at the connection portion can be suppressed, and protrusion of the conductive material to portions other than the connection portion can be suppressed.

  The viscosity of the conductive material at the melting point of the solder is measured as follows.

  The viscosity of the conductive material at the melting point of the solder is determined by using a strain control (manufactured by Reologica) or the like using a strain control of 1 rad, a frequency of 1 Hz, a heating rate of 20 ° C./min, and a measuring temperature range of 25 to 200 ° C. When the melting point exceeds 200 ° C., the upper limit of the temperature is taken as the melting point of the solder). From the measurement results, the viscosity at the melting point (° C.) of the solder is evaluated.

  Thus, the connection structure 1 shown in FIG. 1 is obtained. Note that the second step and the third step may be performed continuously. After performing the second step, the obtained laminated body of the first connection target member 2, the conductive material 11, and the second connection target member 3 is moved to a heating unit, and the third connection target member 2, the conductive material 11, and the second connection target member 3 are moved to the heating unit. A step may be performed. In order to perform the heating, the laminate may be arranged on a heating member, or the laminate may be arranged in a heated space.

  The heating temperature in the third step is preferably 140 ° C. or higher, more preferably 160 ° C. or higher, preferably 450 ° C. or lower, more preferably 250 ° C. or lower, and further preferably 200 ° C. or lower.

  As a heating method in the third step, a method of heating the entire connection structure using a reflow oven or using an oven above the melting point of the solder in the conductive particles and the curing temperature of the thermosetting component, And a method of locally heating only the connection portion of the connection structure.

  Instruments used for the method of locally heating include a hot plate, a heat gun for applying hot air, a soldering iron, and an infrared heater.

  In addition, when heating locally with a hot plate, the metal beneath the connection part is a metal with high thermal conductivity, and other places where heating is not preferable are made of a material with low thermal conductivity such as fluororesin. Preferably, the upper surface of the hot plate is formed.

  The first and second connection target members are not particularly limited. The first and second connection target members specifically include electronic components such as a semiconductor chip, a semiconductor package, an LED chip, an LED package, a capacitor and a diode, a resin film, a printed board, a flexible printed board, and a flexible board. Electronic components such as a flat cable, a rigid flexible substrate, a circuit board such as a glass epoxy substrate and a glass substrate, and the like. Preferably, the first and second connection target members are electronic components.

  It is preferable that at least one of the first connection target member and the second connection target member is a resin film, a flexible printed board, a flexible flat cable, or a rigid flexible board. It is preferable that at least one of the first connection target member and the second connection target member is a resin film, a flexible printed board, a flexible flat cable, or a rigid flexible board. A resin film, a flexible printed board, a flexible flat cable, and a rigid flexible board have properties of high flexibility and relatively light weight. When a conductive film is used to connect such a connection target member, the solder tends to hardly collect on the electrodes. On the other hand, even if a resin film, a flexible printed board, a flexible flat cable, or a rigid flexible board is used by using a conductive paste, the reliability of conduction between the electrodes can be efficiently collected by the solder on the electrodes. Can be increased sufficiently. When using a resin film, a flexible printed board, a flexible flat cable or a rigid flexible board, the reliability of conduction between the electrodes due to the absence of pressure is higher than when using other connection target members such as semiconductor chips. The improvement effect can be obtained even more effectively.

  Examples of the electrodes 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, a silver electrode, a SUS electrode, and a tungsten electrode. When the member to be connected is a flexible printed circuit board, the electrode is preferably a gold electrode, a nickel electrode, a tin electrode, a silver electrode, or a copper electrode. When the member to be connected is a glass substrate, the electrode is preferably an aluminum electrode, a copper electrode, a molybdenum electrode, a silver electrode, or a tungsten electrode. When the electrode is an aluminum electrode, the electrode may be an electrode formed only of aluminum, or may be an electrode in which an aluminum layer is laminated on a surface of a metal oxide layer. Examples of the material of the metal oxide layer include indium oxide doped with a trivalent metal element and zinc oxide doped with a trivalent metal element. Examples of the trivalent metal element include Sn, Al, and Ga.

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

Thermosetting compounds:
"JER152" manufactured by Mitsubishi Chemical Corporation, epoxy resin

Thermosetting agent (thermosetting accelerator (catalyst)):
"BF3-MEA" manufactured by Stella Chemifa, boron trifluoride-monoethylamine complex

Conductive particles:
"Sn42Bi58 (DS-10)" manufactured by Mitsui Kinzoku Mining Co., Ltd.

flux:
(1) Flux 1
Method for preparing flux 1:
24 g of water as a reaction solvent and 13.212 g of glutaric acid (manufactured by Wako Pure Chemical Industries, Ltd.) were placed in a glass bottle and dissolved at room temperature until uniform. Thereafter, 10.715 g of benzylamine (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was stirred for about 5 minutes to obtain a mixed solution. The obtained mixture was put in a refrigerator at 5 to 10 ° C. and left overnight. The precipitated crystals were separated by filtration, washed with water, and dried under vacuum. Flux 1 was obtained by heating the dried crystals at 140 ° C. for 15 minutes to completely melt them and gradually reprecipitating them at 25 ° C. over 30 minutes.

(2) Flux 2
Method for preparing flux 2:
24 g of water as a reaction solvent and 13.212 g of glutaric acid (manufactured by Wako Pure Chemical Industries, Ltd.) were placed in a glass bottle and dissolved at room temperature until uniform. Thereafter, 10.715 g of benzylamine (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was stirred for about 5 minutes to obtain a mixed solution. The obtained mixture was put in a refrigerator at 5 to 10 ° C. and left overnight. The precipitated crystals were separated by filtration, washed with water, and dried under vacuum. Flux 2 was obtained by heating the dried crystals at 160 ° C. for 5 minutes to completely melt them and gradually reprecipitating them at 25 ° C. for 30 minutes.

(3) Flux 3
Flux 3 production method:
24 g of water as a reaction solvent and 13.212 g of glutaric acid (manufactured by Wako Pure Chemical Industries, Ltd.) were placed in a glass bottle and dissolved at room temperature until uniform. Thereafter, 10.715 g of benzylamine (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was stirred for about 5 minutes to obtain a mixed solution. The obtained mixture was put in a refrigerator at 5 to 10 ° C. and left overnight. The precipitated crystals were separated by filtration, washed with water, and dried under vacuum. Flux 3 was obtained by crushing the dried crystals in a mortar.

(4) Flux 4
Method for preparing flux 4:
24 g of water as a reaction solvent and 13.212 g of glutaric acid (manufactured by Wako Pure Chemical Industries, Ltd.) were placed in a glass bottle and dissolved at room temperature until uniform. Thereafter, 10.715 g of benzylamine (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was stirred for about 5 minutes to obtain a mixed solution. The obtained mixture was put in a refrigerator at 5 to 10 ° C. and left overnight. The precipitated crystals were separated by filtration, washed with water, and dried under vacuum. Flux 4 was obtained by crushing the dried crystals with a jet mill crusher manufactured by Nisshin Engineering.

(Examples 1-2 and Comparative Examples 1-3)
(1) Production of conductive material (anisotropic conductive paste) The components shown in Table 1 below were blended in the amounts shown in Table 1 below to obtain a conductive material (anisotropic conductive paste).

(2) Preparation of First Connection Structure (L / S = 50 μm / 50 μm) Using a conductive material (anisotropic conductive paste) immediately after preparation, a first connection structure is prepared as follows. did.

  A glass epoxy substrate (FR-4 substrate) (first connection target member) having a copper electrode pattern (copper electrode thickness: 12 μm) having an L / S of 50 μm / 50 μm and an electrode length of 3 mm on the upper surface was prepared. In addition, a flexible printed circuit board (second connection target member) having a copper electrode pattern (copper electrode thickness: 12 μm) having an L / S of 50 μm / 50 μm and an electrode length of 3 mm on the lower surface was prepared.

  The overlapping area of the glass epoxy board and the flexible printed board was 1.5 cm × 3 mm, and the number of connected electrodes was 75 pairs.

  On the upper surface of the glass epoxy substrate, a conductive material (anisotropic conductive paste) immediately after production is applied by screen printing using a metal mask so as to have a thickness of 100 μm on the electrodes of the glass epoxy substrate, A conductive material (anisotropic conductive paste) layer was formed. Next, the flexible printed circuit board was laminated on the upper surface of the conductive material (anisotropic conductive paste) layer so that the electrodes faced each other. At this time, no pressurization was performed. The weight of the flexible printed board is added to the conductive material (anisotropic conductive paste) layer. From this state, heating was performed so that the temperature of the conductive material (anisotropic conductive paste) layer became 139 ° C. (the melting point of the solder) 5 seconds after the start of the temperature rise. Further, 15 seconds after the start of the temperature rise, the conductive material (anisotropic conductive paste) layer is heated so that the temperature of the conductive material (anisotropic conductive paste) layer becomes 160 ° C., the conductive material (anisotropic conductive paste) layer is cured, and the connection structure is formed. Obtained. No pressure was applied during heating.

(3) Production of Second Connection Structure (L / S = 75 μm / 75 μm) Glass epoxy substrate having a copper electrode pattern (copper electrode thickness 12 μm) having an L / S of 75 μm / 75 μm and an electrode length of 3 mm on the upper surface (FR-4 substrate) (first connection target member) was prepared. Also, a flexible printed board (second connection target member) having a copper electrode pattern (copper electrode thickness: 12 μm) with an L / S of 75 μm / 75 μm and an electrode length of 3 mm on the lower surface was prepared.

  A second connection structure was obtained in the same manner as in the preparation of the first connection structure except that the above-mentioned glass epoxy substrate and flexible printed circuit board having different L / S were used.

(4) Preparation of Third Connection Structure (L / S = 100 μm / 100 μm) Glass epoxy substrate having a copper electrode pattern (copper electrode thickness: 12 μm) having an L / S of 100 μm / 100 μm and an electrode length of 3 mm on the upper surface (FR-4 substrate) (first connection target member) was prepared. Further, a flexible printed board (second connection target member) having a copper electrode pattern (thickness of the copper electrode: 12 μm) having an L / S of 100 μm / 100 μm and an electrode length of 3 mm on the lower surface was prepared.

  A third connection structure was obtained in the same manner as in the production of the first connection structure except that the above-mentioned glass epoxy substrate and flexible printed circuit board having different L / S were used.

(Evaluation)
(1) State of existence of flux The average particle diameter of the obtained flux was measured using a laser microscope (“OLS4100” manufactured by Olympus Corporation), and the particle diameter of 50 arbitrary fluxes was measured and calculated from the average value.

  From the average particle diameter of the obtained flux, the ratio of the number of fluxes having a particle diameter of twice or more the average particle diameter of the flux in 100% of the total number of fluxes, and the average particle diameter of the flux in 100% of the total number of fluxes The ratio of the number of fluxes having a particle diameter of 1.5 times or more of the above was calculated.

(2) Colloid The obtained conductive material (anisotropic conductive paste) was filtered to remove conductive particles from the conductive material (anisotropic conductive paste). The composition from which the conductive particles had been removed was placed in a 10 mL screw tube, and a laser pointer was irradiated from the side of the screw tube to confirm whether or not the Tyndall phenomenon due to the flux was observed. The colloid was determined according to the following criteria. In addition, it was confirmed that the thermosetting compound and the thermosetting agent were dissolved.

[Criteria for colloid]
：: Tyndall phenomenon due to flux is observed ×: Tyndall phenomenon due to flux is not observed

(3) Storage stability The viscosity (η1) at 25 ° C. of the conductive material (anisotropic conductive paste) immediately after preparation was measured. Further, the conductive material (anisotropic conductive paste) immediately after fabrication was left at room temperature for 24 hours, and the viscosity (η2) at 25 ° C. of the conductive material (anisotropic conductive paste) after standing was measured. The viscosity was measured at 25 ° C. and 5 rpm using an E-type viscometer (“TVE22L” manufactured by Toki Sangyo Co., Ltd.). The viscosity increase rate (η2 / η1) was calculated from the measured viscosity value. Storage stability was determined based on the following criteria.

[Criteria for storage stability]
：: Viscosity increase rate (η2 / η1) is 1.5 or less Δ: Viscosity increase rate (η2 / η1) exceeds 1.5 and 2.0 or less ×: Viscosity increase rate (η2 / η1) is 2.0 Exceed

(4) Heat resistance of cured product The obtained conductive material (anisotropic conductive paste) was heated at 150 ° C for 2 hours to obtain a cured product. The glass transition temperature (Tg) of the obtained cured product was measured using a dynamic viscoelasticity measurement device (“Rheogel-E” manufactured by UBM) under the condition of a heating rate of 10 ° C./min. The heat resistance of the cured product was determined according to the following criteria.

[Criteria for determining heat resistance of cured product]
：: Tg of the cured product is 100 ° C. or more Δ: Tg of the cured product is 90 ° C. or more and less than 100 ° C. X: Tg of the cured product is less than 90 ° C.

(5) Solder placement accuracy on electrodes (solder cohesion)
In the obtained first, second, and third connection structures, a portion where the first electrode and the second electrode face each other in the stacking direction of the first electrode, the connection portion, and the second electrode is As a result, the ratio X of the area where the solder portion in the connection portion was arranged in 100% of the area of the portion where the first electrode and the second electrode face each other was evaluated. The placement accuracy (solder cohesion) of the solder on the electrode was determined according to the following criteria.

[Criteria for determining placement accuracy of solder on electrodes (solder cohesion)]
○: Ratio X is 70% or more ：: Ratio X is 60% or more and less than 70% Δ: Ratio X is 50% or more and less than 60% X: Ratio X is less than 50%

(6) Conduction reliability between upper and lower electrodes In the obtained first, second, and third connection structures (n = 15), the connection resistance per connection between the upper and lower electrodes is 4 It was measured by the terminal method. The average value of the connection resistance was calculated. The connection resistance can be obtained by measuring the voltage when a constant current flows from the relationship of voltage = current × resistance. The conduction reliability was determined according to the following criteria.

[Criteria for continuity reliability]
○: The average value of the connection resistance is 50 mΩ or less ○: The average value of the connection resistance is more than 50 mΩ and 70 mΩ or less △: The average value of the connection resistance is more than 70 mΩ and 100 mΩ or less ×: The average value of the connection resistance exceeds 100 mΩ, or Poor connection

(7) Insulation reliability between laterally adjacent electrodes The obtained first, second and third connection structures (n = 15) were left in an atmosphere of 85 ° C. and 85% humidity for 100 hours. Thereafter, 5 V was applied between the horizontally adjacent electrodes, and the resistance was measured at 25 points. The insulation reliability was determined based on the following criteria.

[Criteria for insulation reliability]
○: The average value of the connection resistance is 10 ⁷ Ω or more. ○: The average value of the connection resistance is 10 ⁶ Ω or more and less than 10 ⁷ Ω. Δ: The average value of the connection resistance is 10 ⁵ Ω or more and less than 10 ⁶ Ω. Average value is less than 10 ⁵ Ω

  The results are shown in Table 1 below.

  The same tendency was observed when a resin film, a flexible flat cable, and a rigid flexible substrate were used instead of the flexible printed substrate.

1, 1X Connection structure 2 First connection target member 2a First electrode 3 Second connection target member 3a Second electrode 4, 4X Connection part 4A, 4XA Solder part 4B, 4XB … Curing material part 11… Conductive material 11A… Solder particles (conductive particles)
11B: thermosetting component 21: conductive particles (solder particles)
31 conductive particles 32 base particles 33 conductive part (conductive part having solder)
33A: second conductive portion 33B: solder portion 41: conductive particles 42: solder portion

Claims (8)

Including a plurality of conductive particles having solder on the outer surface portion of the conductive portion, a thermosetting compound, and a flux,
A conductive material comprising at least one of the following first and second configurations.
First configuration: There is no flux having a particle diameter more than twice the average particle diameter of the flux, or the particle diameter is twice or more the average particle diameter of the flux in 100% of the total number of the flux. The second composition: a composition obtained by removing the conductive particles from the conductive material is a colloid, and the flux is present as colloid particles.   There is no flux having a particle diameter of 1.5 times or more the average particle diameter of the flux, or a particle diameter of 1.5 times or more the average particle diameter of the flux in 100% of the total number of the flux. The conductive material according to claim 1, wherein the flux has a number of less than 20%.   The conductive material according to claim 1, wherein the average particle diameter of the flux is 1 μm or less.   The conductive material according to any one of claims 1 to 3, wherein the content of the flux is 1 part by weight or more and 20 parts by weight or less based on 100 parts by weight of the thermosetting compound.   The conductive material according to any one of claims 1 to 4, wherein the content of the flux in the conductive material (100% by weight) is 0.05% by weight or more and 20% by weight or less.   The conductive material according to any one of claims 1 to 5, which is a conductive paste. A first connection target member having a first electrode on its surface;
A second member to be connected having a second electrode on its surface;
The first connection target member, and a connection portion that connects the second connection target member,
The material of the connection portion is a conductive material according to any one of claims 1 to 6,
A connection structure, wherein the first electrode and the second electrode are electrically connected by a solder part in the connection part.   When a portion where the first electrode and the second electrode face each other is viewed in a laminating direction of the first electrode, the connection portion, and the second electrode, the first electrode and the second electrode 8. The connection structure according to claim 7, wherein the solder portion in the connection portion is arranged at 50% or more of 100% of the area of the portion facing the second electrode. 9.

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