JP2017022099A - Conductive material and connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive material capable of efficiently arranging a solder in a conductive particle on an electrode and enhancing conduction reliability between electrodes.SOLUTION: The conductive material contains a plurality of conductive particles and a binder, where the conductive particle has a solder in an outer surface part of a conductor part and a coated part of a polymer with weight average molecular weight of 3000 to 100000 on the outer surface of the conductive part.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a conductive material including conductive particles having solder. The present invention also relates to a connection structure using the conductive material.

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

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

  For example, when electrically connecting the electrode of the flexible printed circuit board and the electrode of the glass epoxy substrate by the anisotropic conductive material, an anisotropic conductive material containing conductive particles is disposed on the glass epoxy substrate. To do. Next, a flexible printed circuit board is laminated, and heated and pressurized. As a result, 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 Document 1 described below describes an anisotropic conductive material including conductive particles and a resin component that cannot be cured at the melting point of the conductive particles. Specifically, the conductive particles include tin (Sn), indium (In), bismuth (Bi), silver (Ag), copper (Cu), zinc (Zn), lead (Pb), cadmium (Cd ), Gallium (Ga), silver (Ag), thallium (Tl), and the like, and alloys of these metals.

  In Patent Document 1, a resin heating step for heating the anisotropic conductive resin 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 for curing the resin component The electrical connection between the electrodes is described. Patent Document 1 describes that mounting is performed with the temperature profile shown in FIG. In Patent Document 1, the conductive particles melt in a resin component that is not completely cured at a temperature at which the anisotropic conductive resin is heated.

  Patent Document 2 below discloses an adhesive tape that includes a resin layer containing a thermosetting resin, solder powder, and a curing agent, and the solder powder and the curing agent are present in the resin layer. Yes. This adhesive tape is in the form of a film, not a paste.

  Patent Document 2 discloses an adhesion method using the adhesive tape. Specifically, a first substrate, an adhesive tape, a second substrate, an adhesive tape, and a third substrate are laminated in this order from the bottom to obtain a laminate. At this time, the first electrode provided on the surface of the first substrate is opposed to the second electrode provided on the surface of the second substrate. Moreover, the 2nd electrode provided in the surface of the 2nd board | substrate and the 3rd electrode provided in the surface of the 3rd board | substrate are made to oppose. Then, the laminate is heated and bonded at a predetermined temperature. Thereby, a connection structure is obtained.

  Further, in Patent Document 3 below, a semiconductor chip having a plurality of connection terminals is disposed so as to face a wiring board having a plurality of electrode terminals, and the electrode terminals of the wiring board and the above-mentioned semiconductor chip A flip chip mounting method for electrically connecting a connection terminal is disclosed. The flip chip mounting method includes (1) a step of supplying a resin containing solder powder and a convection additive onto the surface of the wiring board having the electrode terminals, and (2) the semiconductor chip on the resin surface. (3) a step of heating the wiring substrate to a temperature at which the solder powder melts, and (4) a step of curing the resin after the heating step. In the heating step (3) of the wiring board, a connection body for electrically connecting the electrode terminal and the connection terminal is formed, and in the resin curing step (4), the semiconductor chip is connected to the wiring board. To fix.

JP 2004-260131 A WO2008 / 023452A1 JP 2006-114865 A

  In the case of conventional anisotropic conductive paste containing solder powder or conductive particles having a solder layer on the surface, the solder powder or conductive particles may not be efficiently disposed on the electrodes (lines). In the conventional solder powder or conductive particles, the moving speed of the solder powder or conductive particles onto the electrode may be slow.

  Further, when the electrodes are electrically connected by the method described in Patent Document 1 using the anisotropic conductive material described in Patent Document 1, conductive particles including solder are efficiently formed on the electrodes (lines). May not be placed. Moreover, in the Example of patent document 1, in order to move a solder fully at the temperature more than melting | fusing point of solder, it is hold | maintained at fixed temperature, and the manufacturing efficiency of a connection structure becomes low. When mounting is performed with the temperature profile shown in FIG. 8 of Patent Document 1, the manufacturing efficiency of the connection structure is lowered.

  In Patent Document 2, there is no specific description of the conductive particles used for the anisotropic conductive material. In the Example of patent document 3, the copper layer is formed on the surface of the resin particle, and the electroconductive particle in which the solder layer is formed on the surface of this copper layer is used. The central part of the conductive particles is composed of resin particles. In addition, when the anisotropic conductive material described in Patent Documents 2 and 3 is used, the conductive particles are difficult to be efficiently arranged on the electrodes (lines), and positional displacement between the upper and lower electrodes to be connected may occur. There are things to do.

  An object of the present invention is to provide a conductive material that can efficiently dispose solder in conductive particles on electrodes and can improve conduction reliability between the electrodes. Another object of the present invention is to provide a connection structure using the conductive material.

  According to a wide aspect of the present invention, the conductive particles include a plurality of conductive particles and a binder, the conductive particles have solder on the outer surface portion of the conductive portion, and on the outer surface of the conductive portion. A conductive material having a polymer coating having a weight average molecular weight of 3000 or more and 100000 or less is provided.

  On the specific situation with the electrically-conductive material which concerns on this invention, the said electroconductive particle has a solder particle and the coating | coated part of the said polymer on the outer surface of the said solder particle.

  In a specific aspect of the conductive material according to the present invention, the polymer has a carboxyl group.

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

  On the specific situation with the electrically-conductive material which concerns on this invention, the softening point of the said polymer is lower than melting | fusing point of the said solder.

  On the specific situation with the electrically-conductive material which concerns on this invention, the said binder contains a flux and the softening point of the said polymer is lower than the activation temperature of the said flux.

  On the specific situation with the electrically-conductive material which concerns on this invention, the said polymer is couple | bonded with the hydroxyl group of the said solder by the functional group which can react with the hydroxyl group of the said solder.

  On the specific situation with the electrically-conductive material which concerns on this invention, the thickness of the said coating | coated part is 0.01 micrometer or more and 5 micrometers or less.

  On the specific situation with the electrically-conductive material which concerns on this invention, the average particle diameter of the said electroconductive particle is 1 micrometer or more and 60 micrometers or less.

  On the specific situation with the electrically-conductive material which concerns on this invention, content of the said electroconductive particle is 10 to 80 weight% in 100 weight% of electrically-conductive materials.

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

  The conductive material according to the present invention includes a plurality of conductive particles and a binder, the conductive particles have solder on the outer surface portion of the conductive portion, and on the outer surface of the conductive portion, Since it has the coating part of the polymer whose weight average molecular weight is 3000 or more and 100000 or less, the solder in electroconductive particle can be efficiently arrange | positioned on an electrode and the conduction | electrical_connection reliability between electrodes can be improved.

FIG. 1 is a cross-sectional view schematically showing a connection structure obtained using a conductive material according to an embodiment of the present invention. 2A to 2C are cross-sectional views for explaining 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 as a conductive material. FIG. 5 is a cross-sectional view showing a second example of conductive particles that can be used for the conductive material. FIG. 6 is a cross-sectional view showing a third example of conductive particles that can be used for the conductive material.

  Details of the present invention will be described below.

(Conductive material)
The conductive material according to the present invention includes a plurality of conductive particles and a binder. The conductive particles have a conductive part. The conductive particles have solder on the outer surface portion of the conductive portion. Solder is contained in the conductive part and is a part or all of the conductive part. The conductive particles have a coating part formed of a polymer having a weight average molecular weight of 3000 or more and 100,000 or less on the outer surface of the conductive part. The conductive particles have the polymer coating on the outer surface of the conductive part. Part or all of the conductive portion and the outer surface of the solder are covered with a covering portion formed of the polymer.

  In the present invention, since the above-described configuration is provided, when the electrodes are electrically connected, the solder in the conductive particles easily collects between the upper and lower electrodes, and the solder in the conductive particles is removed from the electrode ( Line). In addition, a part of the solder in the conductive particles is difficult to be disposed in a region (space) where no electrode is formed, and the amount of solder disposed in a region where no electrode is formed can be considerably reduced. In this invention, the electroconductive particle which is not located between the opposing electrodes can be efficiently moved between the opposing electrodes. Therefore, the conduction reliability between the electrodes can be improved. In addition, it is possible to prevent electrical connection between laterally adjacent electrodes that should not be connected, and to improve insulation reliability. Furthermore, it is possible to prevent positional deviation between the electrodes. In the present invention, when the second connection target member is superimposed on the first connection target member having the conductive material disposed on the upper surface, the electrode of the first connection target member and the electrode of the second connection target member Even when the first connection target member and the second connection target member are overlapped in a state where the alignment of the first connection target member and the second connection target member are overlaid, the shift is corrected and the electrode of the first connection target member and the second connection target The electrode of the member can be connected (self-alignment effect). In order to obtain such an effect, using specific conductive particles greatly contributes.

  The covering portion of the conductive particles is formed of a polymer having a weight average molecular weight satisfying a specific range, and the charge on the outer surface of the conductive portion in the conductive particles is controlled. Further, when heat is applied to the conductive material, the weight average molecular weight of the polymer is less than or equal to the upper limit, so that the covering portion is easily detached, the solder on the outer surface portion of the conductive portion is exposed, and the solder moves. Is promoted.

  The conductive particles may be solder particles. The solder particles are formed of solder. The solder particles have solder on the outer surface portion of the conductive portion. As for the said solder particle, both a center part and an electroconductive outer surface are formed with the solder. The solder particles are particles in which both the central portion of the solder particles and the conductive outer surface are solder. The said electroconductive particle may have a base material particle and the electroconductive part arrange | positioned on the surface of this base material particle. In this case, the conductive particles have solder on the outer surface portion of the conductive portion.

  Compared to the case where the conductive particles including the solder particles are used, the case where the conductive particles including the base particles not formed by the solder and the solder portion arranged on the surface of the base particles are used. The conductive particles are less likely to collect on the electrodes, and the conductive particles that have moved onto the electrodes tend to move out of the electrodes because of the low solderability between the conductive particles. There is a tendency that the effect of suppressing misalignment also becomes low. Therefore, it is preferable that the conductive particles have solder particles formed by solder.

  The weight average molecular weight of the polymer is preferably 3000 or more, more preferably 100,000 or less from the viewpoint of more efficiently arranging the solder on the electrodes and further suppressing the displacement between the electrodes.

  The weight average molecular weight indicates a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

  From the viewpoint of more efficiently arranging the solder on the electrodes and further suppressing the displacement between the electrodes, the softening point of the polymer is preferably lower than the melting point of the solder. The absolute value of the difference between the softening point of the polymer and the melting point of the solder is preferably 10 ° C. or more from the viewpoint of more efficiently arranging the solder on the electrodes and further suppressing the displacement between the electrodes. Preferably it is 20 degreeC or more, Preferably it is 80 degrees C or less, More preferably, it is 70 degrees C or less.

  From the viewpoint of further improving the conduction reliability, the conductive material and the binder preferably include a flux. From the viewpoint of more efficiently arranging the solder on the electrodes and further suppressing the displacement between the electrodes, the softening point of the polymer is preferably lower than the activation temperature of the flux. The absolute value of the difference between the softening point of the polymer and the activation temperature of the flux is preferably 5 ° C. or more from the viewpoint of more efficiently arranging the solder on the electrodes and further suppressing the displacement between the electrodes. Preferably it is 15 degreeC or more, Preferably it is 70 degrees C or less, More preferably, it is 60 degrees C or less.

  The softening point of the polymer is preferably 10 ° C or higher, more preferably 30 ° C or higher, preferably 180 ° C or lower, more preferably 160 ° C or lower.

  The softening point means an endothermic temperature measured by DSC.

  In order to arrange the solder more efficiently on the electrode, the viscosity (η25) at 25 ° C. of the conductive material is preferably 10 Pa · s or more, more preferably 50 Pa · s or more, and further preferably 100 Pa · s or more. Yes, preferably 800 Pa · s or less, more preferably 600 Pa · s or less, and even more preferably 500 Pa · s or less.

  The said viscosity ((eta) 25) can be suitably adjusted with the kind and compounding quantity of a compounding component. Further, the use of a filler can make the viscosity relatively high.

  The viscosity (η25) can be measured using, for example, an E-type viscometer (“TVE22L” manufactured by Toki Sangyo Co., Ltd.) and the like 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 more efficiently disposing the solder in the conductive particles on the electrode, the conductive material is preferably an anisotropic conductive paste. The conductive material is preferably used for electrical connection of electrodes. The conductive material is preferably a circuit connection material.

  The conductive material and the binder preferably contain a thermoplastic component or a thermosetting component. The conductive material and the binder may contain a thermoplastic component or a thermosetting component. The conductive material and the binder preferably include a thermosetting component. The conductive material and the binder preferably include a thermosetting compound and a thermosetting agent. The binder is preferably a liquid component at 25 ° C. or a component that becomes liquid at the time of conductive connection.

  Hereinafter, each component contained in the conductive material will be described.

(Conductive particles)
The conductive particles electrically connect the electrodes of the connection target member. The conductive particles have solder on the outer surface portion of the conductive portion.

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

  The conductive particles 21 shown in FIG. 4 have solder particles 22 and a covering portion 23 disposed on the outer surface of the solder particles 22. The solder particles 22 and the covering portion 23 are in contact with each other. The solder particles 22 are entirely formed of solder. The solder particles 22 do not have base material particles in the core, and are not core-shell particles. The solder particles 22 are formed of solder at both the central portion and the outer surface.

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

  The conductive particle 31 shown in FIG. 5 includes a base particle 32, a conductive part 33 disposed on the surface of the base particle 32, and a covering part 34 disposed on the outer surface of the conductive part 33. The conductive portion 33 and the covering portion 34 are in contact with each other. The conductive portion 33 covers the surface of the base particle 32. The covering portion 34 covers the surface of the conductive portion 33. The conductive particle 31 is a coated particle in which the surface of the base particle 32 is covered with the conductive portion 33 and the surface of the conductive portion 33 is further covered with the covering portion 34.

  The conductive portion 33 includes a second conductive portion 33A and a solder portion 33B (first conductive portion) disposed on the surface of the second conductive portion 33A. The conductive particle 31 includes a second conductive portion 33A between the base particle 32 and the solder portion 33B. Therefore, the conductive particles 31 include the base particle 32, the second conductive portion 33A disposed on the surface of the base particle 32, and the solder portion 33B disposed on the surface of the second conductive portion 33A. Is provided. As described above, the conductive portion 33 may have a multilayer structure or may have a stacked structure of two or more layers.

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

  As described above, the conductive portion 33 in the conductive particle 31 has a two-layer structure. The conductive particle 41 shown in FIG. 6 has a solder part 42 as a single-layer conductive part. The conductive particle 41 includes a base particle 32, a solder portion 42 disposed on the surface of the base particle 32, and a covering portion 43 on the outer surface of the solder portion 42. The solder part 42 and the covering part 43 are in contact with each other.

  Examples of the substrate particles include resin particles, inorganic particles excluding metal particles, organic-inorganic hybrid particles, and metal particles. The substrate particles are preferably substrate particles excluding metal, and are preferably resin particles, inorganic particles excluding metal particles, or organic-inorganic hybrid particles. The substrate particles may be copper particles. The base particle may have a core and a shell disposed on the surface of the core, or may be a core-shell particle. The core may be an organic core, and the shell may be an inorganic shell.

  Various organic materials are suitably used as the resin for forming the resin particles. Examples of the resin for forming the resin particles include polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene, and polybutadiene; acrylic resins such as polymethyl methacrylate and polymethyl acrylate; 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, polyethylene terephthalate, polysulfone, polyphenylene oxide , Polyacetal, polyimide, polyamideimide, polyether ether Tons, polyether sulfone, divinyl benzene polymer, and divinylbenzene copolymer, and the like. Examples of the divinylbenzene copolymer include divinylbenzene-styrene copolymer and divinylbenzene- (meth) acrylic acid ester copolymer. Since the hardness of the resin particles can be easily controlled within a suitable range, the resin for forming the resin particles is a polymer obtained by polymerizing one or more polymerizable monomers having an ethylenically unsaturated group. It is preferably a coalescence.

  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 And a crosslinkable monomer.

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

  Examples of the crosslinkable monomer include tetramethylolmethane tetra (meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolmethane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and dipenta Erythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, glycerol tri (meth) acrylate, glycerol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) Polyfunctional (meth) acrylate compounds such as acrylate, (poly) tetramethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate; triallyl (iso) cyanide Silane-containing monomers such as salts, triallyl trimellitate, divinylbenzene, diallyl phthalate, diallylacrylamide, 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 this method include a method of suspension polymerization in the presence of a radical polymerization initiator, and a method of polymerizing by swelling a monomer together with a radical polymerization initiator using non-crosslinked seed particles.

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

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

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

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

  The particle diameter of the core is preferably 0.5 μm or more, more preferably 1 μm or more, preferably 100 μm or less, more preferably 60 μm or less, still more preferably 30 μm or less, particularly preferably 15 μm or less, and most preferably 10 μm or less. It is. When the particle diameter of the core is not less than the above lower limit and not more than the above upper limit, conductive particles more suitable for electrical connection between electrodes can be obtained, and the base particles can be suitably used for the use of conductive particles. Become. For example, when the particle diameter of the core is not less than the lower limit and not more than the upper limit, when the electrodes are connected using the conductive particles, the contact area between the conductive particles and the electrodes is sufficiently large, and Aggregated conductive particles are hardly formed when the conductive layer is formed. Further, the distance between the electrodes connected via the conductive particles does not become too large, and the conductive layer is difficult to peel from the surface of the base material particles.

  The particle diameter of the core means the diameter when the core is a true sphere, and the maximum diameter when the core is a shape other than the true sphere. Moreover, the particle diameter of a core means the average particle diameter which measured the core with arbitrary particle diameter measuring apparatuses. For example, a particle size distribution measuring machine using principles such as laser light scattering, electrical resistance value change, and image analysis after imaging can be used.

  The thickness of the shell is preferably 100 nm or more, more preferably 200 nm or more, preferably 5 μm or less, more preferably 3 μm or less. When the thickness of the shell is not less than the above lower limit and not more than the above upper limit, conductive particles more suitable for electrical connection between the electrodes can be obtained, and the base particles can be suitably used for the use of conductive particles. . The thickness of the shell is an average thickness per base particle. The thickness of the shell can be controlled by controlling the sol-gel method.

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

  The particle diameter of the substrate particles is preferably 0.1 μm or more, more preferably 1 μm or more, further preferably 1.5 μm or more, particularly preferably 2 μm or more, preferably 100 μm or less, more preferably 60 μm or less, more More preferably, it is 30 μm or less, more preferably 20 μm or less, still more preferably 10 μm or less, particularly preferably 5 μm or less, and most preferably 3 μm or less. When the particle diameter of the base material 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 conduction reliability between the electrodes can be further improved and the connection is made through the conductive particles. The connection resistance between the formed electrodes can be further reduced. When the particle diameter of the substrate particles is not more than the above upper limit, the conductive particles are easily compressed, the connection resistance between the electrodes can be further reduced, and the interval between the electrodes can be further reduced. it can.

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

  The particle diameter of the substrate particles is particularly preferably 2 μm or more and 5 μm or less. When the particle diameter of the substrate particles is in the range of 2 μm or more and 5 μm or less, the distance between the electrodes can be further reduced, and even if the thickness of the conductive layer is increased, small conductive particles can be obtained. Can do.

  The method for forming the conductive part on the surface of the base particle and the method for forming the solder part on the surface of the base particle or the surface of the second conductive part are not particularly limited. Examples of the method for forming the conductive portion and the solder portion include a method by electroless plating, a method by electroplating, a method by physical collision, a method by mechanochemical reaction, a method by physical vapor deposition or physical adsorption, And a method of coating the surface of the substrate particles with a paste containing metal powder or metal powder and a binder. Among these, a method using electroless plating, electroplating, or physical collision is preferable. Examples of the method by physical vapor deposition include methods such as vacuum vapor deposition, ion plating, and ion sputtering. Further, in the method based on the physical collision, for example, a sheeter composer (manufactured by Tokuju Kogakusha Co., Ltd.) or the like is used.

  The melting point of the substrate particles is preferably higher than the melting points of the conductive part and the solder part. The melting point of the substrate particles is preferably higher than 160 ° C, more preferably higher than 300 ° C, still more preferably higher than 400 ° C, and particularly preferably higher than 450 ° C. The melting point of the substrate particles may be less than 400 ° C. The melting point of the substrate particles may be 160 ° C. or less. The softening point of the substrate particles is preferably 260 ° C. or higher. The softening point of the substrate 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 parts (solder part, second conductive part). That is, in the conductive particles, two or more conductive portions may be stacked. When the conductive part has two or more layers, the conductive particles preferably have solder on the outer surface portion of the conductive part.

  The solder is preferably a metal (low melting point metal) having a melting point of 450 ° C. or lower. The solder part is preferably a metal layer (low melting point metal layer) having a melting point of 450 ° C. or lower. The low melting point metal layer is a layer containing a low melting point metal. The solder in the conductive particles is preferably a metal (low melting point metal) having a melting point of 450 ° C. or lower. The low melting point metal is a metal having a melting point of 450 ° C. or lower. 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. It is 70% by weight or more, particularly preferably 90% by weight or more. When the content of tin contained in the solder in the conductive particles is not less than the above lower limit, the conduction reliability between the conductive particles and the electrode is further enhanced.

  The tin content is determined using a high frequency inductively coupled plasma optical emission spectrometer (“ICP-AES” manufactured by Horiba, Ltd.) or a fluorescent X-ray analyzer (“EDX-800HS” manufactured by Shimadzu). It can be measured.

  By using the conductive particles having the solder on the conductive surface, 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 not in point contact but in surface contact, the connection resistance is lowered. In addition, the use of conductive particles having solder on the conductive surface increases the bonding strength between the solder and the electrode. As a result, peeling between the solder and the electrode is further less likely to occur, and conduction reliability and conduction reliability are improved. Effectively high.

  The low melting point metal constituting the solder part and the solder particles is 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. Especially, since it is excellent in the wettability with respect to an electrode, it is preferable that the said low melting metal is a tin, a tin-silver alloy, a tin-silver-copper alloy, a tin-bismuth alloy, and a tin-indium alloy. More preferred are a tin-bismuth alloy and a tin-indium alloy.

  The material constituting the solder (solder part) is preferably a filler material having a liquidus of 450 ° C. or lower based on JIS Z3001: Welding terms. Examples of the composition of the solder include a metal composition containing zinc, gold, silver, lead, copper, tin, bismuth, indium and the like. Among them, a tin-indium system (117 ° C. eutectic) or a tin-bismuth system (139 ° C. eutectic) which is low-melting 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, the solder in the conductive particles is nickel, copper, antimony, aluminum, zinc, iron, gold, titanium, phosphorus, germanium, tellurium, cobalt, bismuth, manganese. Further, it may contain a metal such as chromium, molybdenum and palladium. Moreover, from the viewpoint of further increasing the bonding strength between the solder and the electrode, 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.

  The melting point of the second conductive part is preferably higher than the melting point of the solder part. The melting point of the second conductive part is preferably more than 160 ° C, more preferably more than 300 ° C, still more preferably more than 400 ° C, still more preferably more than 450 ° C, particularly preferably more than 500 ° C, most preferably Preferably it exceeds 600 degreeC. Since the solder part has a low melting point, it melts during conductive connection. It is preferable that the second conductive portion does not melt during conductive connection. The conductive particles are preferably used by melting solder, preferably used by melting the solder part, and used without melting the solder part and melting the second conductive part. It is preferred that Since the melting point of the second conductive part is higher than the melting point of the solder part, it is possible to melt only the solder part without melting the second conductive part during 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, particularly preferably Is 50 ° C. or higher, most preferably 100 ° C. or higher.

  The second conductive part preferably contains a metal. The metal which comprises the said 2nd electroconductive part is not specifically limited. Examples of the metal include gold, silver, copper, platinum, palladium, zinc, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium and cadmium, and alloys thereof. Further, tin-doped indium oxide (ITO) may be used as the metal. As for the said metal, only 1 type may be used and 2 or more types may be used together.

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

  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 part is not less than the above lower limit and not more than the above upper limit, sufficient conductivity can be obtained, and the conductive particles are not too hard, and the conductive particles are sufficiently deformed at the time of connection between the electrodes. .

  The said coating | coated part is formed with the polymer whose weight average molecular weight is 3000 or more and 100,000 or less. Examples of the polymer include polyester, (meth) acrylic polymer, polyether, and phenoxy resin. As for the said polymer, only 1 type may be used and 2 or more types may be used together. From the viewpoint of more efficiently arranging the solder on the electrodes and further suppressing the displacement between the electrodes, the polymer is preferably a polyester.

  From the viewpoint of more efficiently arranging the solder on the electrodes and further suppressing the displacement between the electrodes, the polymer preferably has a carboxyl group. The polymer having a carboxyl group has a flux effect and contributes to a reduction in connection resistance between the electrodes.

  From the viewpoint of more efficiently arranging the solder on the electrodes and further suppressing the displacement between the electrodes, the polymer preferably has a functional group capable of reacting with the hydroxyl group of the solder. In the conductive particles, The polymer is preferably bonded to the solder hydroxyl group by a function capable of reacting with the solder hydroxyl group. Note that no covalent bond may be formed between the polymer and the solder. Examples of the functional group of the polymer include a carboxyl group, an isocyanate group, a phosphoric acid group, a phosphorous acid group, an amino group, and a hydroxyl group. The functional group of the polymer is preferably a carboxyl group.

  As a method for producing the above conductive particles, after putting conductive particles having no coating portion in a liquid containing a polymer and a solvent, a polymer poor solvent is dropped and the polymer is applied to the surface of the conductive particles. After depositing conductive particles that do not have a coating in a liquid containing a polymer and a solvent, or by dropping a polymer poor solvent to deposit the polymer on the surface of the conductive particles , A method of reacting the functional group of the polymer with the functional group on the surface of the conductive particle, or after putting the conductive particle having no coating portion in a liquid containing the polymer and the solvent, the solvent while stirring And then the polymer is coated on the surface of the conductive particles, the functional groups on the conductive particles are reacted with the functional groups of the polymerization initiator of the polymer, and then the monomer is polymerized by the polymerization initiator. On how to produce polymers and on conductive particles And functional group, after reacting the functional groups of the monomers, relative to the monomer, polyaddition monomers by polymerization, by polycondensation or the like, methods or the like to produce a polymer.

  The functional group of the polymerization initiator used when the functional group on the conductive particle is reacted with the functional group of the polymerization initiator of the polymer includes a carboxyl group, an isocyanate group, a phosphoric acid group, a phosphorous acid group, and an amino group. Or a hydroxyl group is preferable and a carboxyl group is especially preferable.

  Examples of the polymerization initiator include 2,2′-Azobis [N- (2-carboxyethyl) -2-methylpropionamide] n-hydrate (“VA-057” manufactured by Wako Pure Chemical Industries, Ltd.), 4,4′-Azobis (4 -Cyanopentanoic Acid) ("V-501" manufactured by Wako Pure Chemical Industries, Ltd.), 2,2'-Azobis [2-methyl-N- (2-hydroxyethyl) propionamide] (hydroxyl group, "VA-" manufactured by Wako Pure Chemical Industries, Ltd.) 086 "), 2,2'-Azobis (2-amidinopropane) Dihydrochloride (amino group," V-50 "manufactured by Wako Pure Chemical Industries, Ltd.), 1-[(1-Cyano-1-methylethyl) azo] formide Kojun Pharmaceutical Industry Ltd. "V-30"), and the like.

  The thickness of the covering portion is preferably 0.01 μm or more, more preferably 0.03 μm or more, preferably 5 μm or less, more preferably 3 μm or less. When the thickness of the covering portion is not less than the above lower limit and not more than the above upper limit, the solder can be arranged more efficiently on the electrodes, and the displacement between the electrodes can be further suppressed.

  The average particle diameter of the conductive particles is preferably 0.5 μm or more, more preferably 1 μm or more, further preferably 3 μm or more, particularly preferably 5 μm or more, preferably 100 μm or less, more preferably 60 μm or less, and much more. It is preferably 40 μm or less, more preferably 30 μm or less, still more preferably 20 μm or less, particularly preferably 15 μm or less, and most preferably 10 μm or less. When the average particle diameter of the conductive particles is not less than the above lower limit and not more than the above upper limit, the conductive particles can be more efficiently arranged on the electrode. The average particle diameter of the conductive particles is particularly preferably 3 μm or more and 30 μm or less.

  The “average particle size” of the conductive particles indicates a number average particle size. The average particle diameter of the conductive particles is obtained, for example, by observing 50 arbitrary conductive particles with an electron microscope or an optical microscope, calculating an average value, or performing laser diffraction particle size distribution measurement.

  The variation coefficient of the particle diameter 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 variation coefficient of the particle diameter is not less than the above lower limit and not more than the above upper limit, the solder can be more efficiently disposed on the electrode. However, the coefficient of variation of the particle diameter of the conductive particles may be less than 5%.

  The coefficient of variation (CV value) is expressed by the following equation.

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

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

  The content of the conductive particles in 100% by weight of the conductive material is preferably 1% by weight or more, more preferably 2% by weight or more, still more preferably 10% by weight or more, particularly preferably 20% by weight or more, most preferably. It is 30% by weight or more, preferably 80% by weight or less, more preferably 60% by weight or less, and still more preferably 50% by weight or less. When the content of the conductive particles is not less than the above lower limit and not more than the above upper limit, the conductive particles can be arranged more efficiently on the electrodes, and it is easy to arrange many conductive particles between the electrodes. Therefore, the conduction reliability is further enhanced. From the viewpoint of further improving the conduction reliability, the content of the conductive particles is preferably large.

(Thermoplastic component)
The thermoplastic component is preferably a thermoplastic compound. Examples of the thermoplastic compound include phenoxy resin, urethane resin, (meth) acrylic resin, polyester resin, polyimide resin, and polyamide resin. As for the said thermoplastic compound, only 1 type may be used and 2 or more types may be used together.

  The content of the thermoplastic compound in 100% by weight of the conductive material is preferably 20% by weight or more, more preferably 40% by weight or more, still more preferably 50% by weight or more, and preferably 99% by weight or less. Preferably it is 98 weight% or less, More preferably, it is 90 weight% or less, Most preferably, it is 80 weight% or less. From the viewpoint of further improving the impact resistance, it is preferable that the content of the thermoplastic compound is large.

(Thermosetting compound: thermosetting component)
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, phenolic 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 improving the connection reliability, an epoxy compound is preferable. As for the said thermosetting compound, only 1 type may be used and 2 or more types may be used together.

  From the viewpoint of efficiently arranging the solder particles on the electrodes, effectively suppressing misalignment between the electrodes, and further improving the conduction reliability and insulation reliability between the electrodes, the thermosetting compound is crystalline. It is preferable that a thermosetting compound is included. As for the said crystalline thermosetting compound, only 1 type may be used and 2 or more types may be used together.

  From the viewpoint of arranging solder particles more efficiently on the electrodes, more effectively suppressing displacement between the electrodes, and further improving the conduction reliability and insulation reliability between the electrodes, the above crystalline thermosetting The active compound is preferably solid at 25 ° C.

  From the viewpoint of arranging solder particles more efficiently on the electrodes, more effectively suppressing displacement between the electrodes, and further improving the conduction reliability and insulation reliability between the electrodes, the above crystalline thermosetting The melting point of the functional compound is preferably 80 ° C. or higher, more preferably 85 ° C. or higher, preferably 150 ° C. or lower, more preferably 140 ° C. or lower.

  From the viewpoint of arranging solder particles more efficiently on the electrodes, more effectively suppressing displacement between the electrodes, and further improving the conduction reliability and insulation reliability between the electrodes, the above crystalline thermosetting The molecular weight of the functional compound is preferably 300 or more, more preferably 350 or more, preferably 500 or less, more preferably 400 or less.

  The molecular weight means a molecular weight that can be calculated from the structural formula when the thermosetting compound is not a polymer and when the structural formula of the thermosetting compound can be specified. Moreover, when the said thermosetting compound is a polymer, a weight average molecular weight is meant.

  Examples of the crystalline thermosetting compound include epoxy compounds and (meth) acrylic compounds.

  An aromatic epoxy compound is mentioned as said epoxy compound. Crystalline epoxy compounds such as resorcinol type epoxy compounds, naphthalene type epoxy compounds, biphenyl type epoxy compounds, benzophenone type epoxy compounds, isocyanuric type epoxy compounds are preferred. In particular, 2,4-bis (glycidyloxy) benzophenone, 4,4'-bis (glycidyloxy) benzophenone, and isocyanuric epoxy compounds are preferable. Examples of the isocyanuric epoxy compounds include TEPIC-S, TEPIC-G, TEPIC-HP, TEPIC-L, TEPIC-PAS, TEPIC-VL, and TEPIC-UC manufactured by Nissan Chemical Co., Ltd. By using the preferable epoxy compound, the first connection target member and the second connection target are high when the connection target member is bonded to each other when the viscosity is high and acceleration is applied by impact such as conveyance. The positional deviation from the member can be suppressed, and the viscosity of the conductive material can be greatly reduced by the heat at the time of curing, and the aggregation of solder particles can be efficiently advanced.

  The (meth) acrylic compound is a compound having a (meth) acryloyl group. Examples of the (meth) acrylic compound include epoxy (meth) acrylate compounds. A compound in which a (meth) acryloyl group is introduced into the epoxy compound with (meth) acrylic acid or the like is preferable.

  From the viewpoint of arranging solder particles more efficiently on the electrodes, more effectively suppressing displacement between the electrodes, and further improving the conduction reliability and insulation reliability between the electrodes, the above crystalline thermosetting The functional compound is particularly preferably a benzophenone type epoxy compound, and most preferably 2,4-bis (glycidyloxy) benzophenone, 4,4′-bis (glycidyloxy) benzophenone or an isocyanuric type epoxy compound.

  The content of the thermosetting compound in 100% by weight of the conductive material is preferably 20% by weight or more, more preferably 40% by weight or more, still more preferably 50% by weight or more, and preferably 99% by weight or less. More preferably, it is 98 weight% or less, More preferably, it is 90 weight% or less, Most preferably, it is 80 weight% or less. From the viewpoint of further improving the impact resistance, it is preferable that the content of the thermosetting compound is large.

  In 100% by weight of the conductive material, the content of the crystalline thermosetting compound is preferably 20% by weight or more, more preferably 40% by weight or more, still more preferably 50% by weight or more, and preferably 99% by weight. Hereinafter, it is more preferably 98% by weight or less, further preferably 90% by weight or less, and particularly preferably 80% by weight or less.

  The content of the crystalline thermosetting compound is preferably 10% by weight or more, more preferably 30% by weight or more, still more preferably 50% by weight or more, particularly preferably in 100% by weight of the total thermosetting compound. Is 70% by weight or more, preferably 100% by weight or less.

(Thermosetting agent: thermosetting component)
The thermosetting agent thermosets the thermosetting compound. Examples of the thermosetting agent include imidazole curing agents, amine curing agents, phenol curing agents, polythiol curing agents, and other thiol curing agents, acid anhydrides, thermal cation initiators (thermal cation curing agents), and thermal radical generators. It is done. As for the said thermosetting agent, only 1 type may be used and 2 or more types may be used together.

  An imidazole curing agent, a thiol curing agent, or an amine curing agent is preferable because the conductive material can be cured more rapidly at a low temperature. Moreover, since a storage stability becomes high when the curable compound curable by heating and the thermosetting agent are mixed, a latent curing agent is preferable. The latent curing agent is preferably a latent imidazole curing agent, a latent thiol curing agent, or a latent amine curing agent. In addition, the said thermosetting agent may be coat | covered with polymeric substances, such as a polyurethane resin or a polyester resin.

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

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

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

  Examples of the thermal cation initiator (thermal cation curing agent) include iodonium cation curing agents, oxonium cation curing agents, and sulfonium cation curing agents. 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, and examples thereof include azo compounds and organic peroxides. 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 70 ° C. or higher, still more preferably 80 ° C. or higher, preferably 250 ° C. or lower, more preferably 200 ° C. or lower, still more preferably 150 ° C. Hereinafter, it is particularly preferably 140 ° C. or lower. When the reaction start temperature of the thermosetting agent is not less than the above lower limit and not more than the above upper limit, the solder is more efficiently arranged on the electrode. The reaction initiation temperature of the thermosetting agent is particularly preferably 80 ° C. or higher and 140 ° C. or lower.

  From the viewpoint of more efficiently arranging the solder on the electrode, the reaction initiation temperature of the thermosetting agent is preferably higher than the melting point of the solder, more preferably 5 ° C or higher, more preferably 10 ° C or higher. More preferably.

  The reaction start temperature of the thermosetting agent means a temperature at which the exothermic peak of DSC starts to rise.

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

  The content of the thermosetting agent is preferably 0.01 parts by weight or more, more preferably 1 part by weight or more, preferably 200 parts by weight or less, based on 100 parts by weight of the crystalline thermosetting compound. The amount is preferably 100 parts by weight or less, more preferably 75 parts by weight or less. Further, the content of the thermosetting agent is preferably 0.01 parts by weight or more, more preferably 1 part by weight or more, and preferably 200 parts by weight or less with respect to 100 parts by weight as a whole of the thermosetting compound. More preferably, it is 100 parts by weight or less, and still more preferably 75 parts by weight or less. When the content of the thermosetting agent is not less than the above lower limit, it is easy to sufficiently cure the conductive material. When the content of the thermosetting agent is not more than the above upper limit, it is difficult for an excess thermosetting agent that did not participate in curing after curing to remain, and the heat resistance of the cured product is further enhanced.

(flux)
The conductive material and the binder preferably contain a flux. By using flux, the solder can be more effectively placed on the electrode. Moreover, the connection resistance between electrodes becomes still lower by the expression of the flux effect. The flux is not particularly limited. As the flux, a flux generally used for soldering or the like can be used. Examples of the flux include zinc chloride, a mixture of zinc chloride and an inorganic halide, a mixture of zinc chloride and an inorganic acid, a molten salt, phosphoric acid, a derivative of phosphoric acid, an organic halide, hydrazine, an organic acid, and pine resin. Etc. As for the said flux, only 1 type may be used and 2 or more types may be used together.

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

  The rosin is a rosin composed mainly of abietic acid. The flux is preferably rosins, and more preferably abietic acid. By using this preferable flux, the conduction reliability between the electrodes is further enhanced.

  The active temperature (melting point) of the flux is preferably 50 ° C. or higher, more preferably 70 ° C. or higher, still more preferably 80 ° C. or higher, preferably 200 ° C. or lower, more preferably 190 ° C. or lower, even more preferably 160. ° C or lower, more preferably 150 ° C or lower, still more preferably 140 ° C or lower. When the activation temperature of the flux is not less than the above lower limit and not more than the above upper limit, the flux effect is more effectively exhibited and the solder is more efficiently arranged on the electrode. The active temperature (melting point) of the flux is preferably 80 ° C. or higher and 190 ° C. or lower. The activation temperature (melting point) of the flux is particularly preferably 80 ° C. or higher and 140 ° C. or lower.

  The flux having an active temperature (melting point) of 80 ° C. or higher and 190 ° C. or lower includes succinic acid (melting point 186 ° C.), glutaric acid (melting point 96 ° C.), adipic acid (melting point 152 ° C.), pimelic acid (melting point) 104 ° C.), dicarboxylic acids such as suberic acid (melting point 142 ° C.), benzoic acid (melting point 122 ° C.), malic acid (melting point 130 ° C.) and the like.

  The boiling point of the flux is preferably 200 ° C. or lower.

  From the viewpoint of more efficiently arranging the solder on the electrode, the melting point of the flux is preferably higher than the melting point of the solder, more preferably 5 ° C or higher, and even more preferably 10 ° C or higher. .

  From the viewpoint of more efficiently arranging the solder on the electrode, the melting point of the flux is preferably higher than the reaction start temperature of the thermosetting agent, more preferably 5 ° C or higher, more preferably 10 ° C or higher. More preferably.

  The said flux may be disperse | distributed in the electrically-conductive material and may adhere on the surface of electroconductive particle.

  The flux is preferably a flux that releases cations by heating. By using a flux that releases cations upon heating, the solder can be placed more efficiently on the electrode.

  Examples of the flux that releases cations by the heating include the thermal cation initiator (thermal cation curing agent).

  The content of the flux in 100% by weight of the conductive material is preferably 0.5% by weight or more, preferably 30% by weight or less, more preferably 25% by weight or less. The conductive material may not contain flux. When the flux content is not less than the above lower limit and not more than the above upper limit, it becomes more difficult to form an oxide film on the surface of the solder and the electrode, and the oxide film formed on the surface of the solder and the electrode is more effective. Can be 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 distance at which the solder aggregates can be suppressed, and the conductive particles can be uniformly aggregated over all the electrodes of the substrate.

  The content of the filler in 100% by weight of the conductive material is preferably 0% by weight or more, preferably 5% by weight or less, more preferably 2% by weight or less, and further preferably 1% by weight or less. When the content of the filler is not less than the above lower limit and not more than the above upper limit, the solder is more efficiently arranged on the electrode.

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

(Connection structure and method of manufacturing connection structure)
A connection structure according to the present invention includes a first connection target member having at least one first electrode on the surface, a second connection target member having at least one second electrode on the surface, and the first The connection object member and the connection part which has connected the said 2nd connection object member are provided. In the connection structure according to the present invention, the material of the connection portion is the conductive material described above. In the connection structure according to the present invention, the first electrode and the second electrode are electrically connected by a solder portion in the connection portion.

  The manufacturing method of the connection structure according to the present invention includes the step of disposing the conductive material on the surface of the first connection target member having at least one first electrode on the surface, using the conductive material described above. The second connection object member having at least one second electrode on the surface opposite to the first connection object member side of the conductive material, the first electrode and the second electrode The first connection target member and the second connection target member are connected by heating the conductive material to a temperature equal to or higher than the melting point of the solder in the conductive particles, and the step of arranging the electrodes to face each other. Forming a connecting portion made of the conductive material, and electrically connecting the first electrode and the second electrode by a solder portion in the connecting portion. Preferably, the conductive material is heated above the curing temperature of the thermosetting compound.

  In the connection structure according to the present invention and the method for manufacturing the connection structure according to the present invention, since the specific conductive material is used, the solder in the conductive particles gathers between the first electrode and the second electrode. It is easy and the solder can be efficiently arranged on the electrode (line). In addition, a part of the solder is difficult to be disposed in a region (space) where no electrode is formed, and the amount of solder disposed in a region where no electrode is formed can be considerably reduced. Therefore, the conduction reliability between the first electrode and the second electrode can be improved. In addition, it is possible to prevent electrical connection between laterally adjacent electrodes that should not be connected, and to improve insulation reliability.

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

  The thickness of the solder part 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 wetted area on the surface of the electrode (area where the solder is in contact with 100% of the exposed area of the electrode) is preferably 50% or more, more preferably 70% or more, and preferably 100% or less.

  In the method for manufacturing a connection structure according to the present invention, in the step of arranging the second connection target member and the step of forming the connection portion, no pressure is applied, and the second connection is applied to the conductive material. The weight of the target member is preferably added, and in the step of arranging the second connection target member and the step of forming the connection portion, the conductive material exceeds the weight force of the second connection target member. It is preferable that no pressure is applied. In these cases, the uniformity of the amount of solder can be further enhanced in the plurality of solder portions. Furthermore, the thickness of the solder portion can be increased more effectively, so that a large amount of solder is easily collected between the electrodes, and the solder can be arranged more efficiently on the electrodes (lines). Further, a part of the solder is difficult to be disposed in a region (space) where no electrode is formed, and the amount of solder disposed in a region where no electrode is formed can be further reduced. Therefore, the conduction reliability between the electrodes can be further enhanced. In addition, the electrical connection between the laterally adjacent electrodes that should not be connected can be further prevented, and the insulation reliability can be further improved.

  Moreover, if a conductive paste is used instead of a conductive film, it becomes easy to adjust the thickness of the connection part and the solder part depending on the amount of the conductive paste applied. On the other hand, in the conductive film, in order to change or adjust the thickness of the connection portion, it is necessary to prepare a conductive film having a different thickness or to prepare a conductive film having a predetermined thickness. There is. Moreover, in the conductive film, it tends to be difficult to sufficiently lower the melt viscosity of the conductive film at the melting temperature of the solder, and there is a problem that the aggregation of the solder is easily inhibited.

  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 an embodiment of the present invention.

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

  The connection portion 4 includes a solder portion 4A in which a plurality of conductive particles are gathered and joined to each other, and a cured product portion 4B in which a thermosetting component is thermally cured.

  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 portion 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 product portion 4B portion) different from the solder portion 4A gathered between the first electrode 2a and the second electrode 3a. In an area different from the solder part 4A (hardened product part 4B part), there is no solder separated from the solder part 4A. If the amount is small, the solder may be present in a region (cured product 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, after a plurality of conductive particles gather between the first electrode 2a and the second electrode 3a and the plurality of conductive particles melt, the conductive particles The melted material solidifies after the surface of the electrode wets and spreads to form the solder portion 4A. For this reason, the connection area of 4 A of solder parts and the 1st electrode 2a, and 4 A of solder parts, and the 2nd electrode 3a becomes large. That is, by using the conductive particles, the solder portion 4A, the first electrode 2a, and the solder are compared with the case where the conductive outer surface is made 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, the conduction | electrical_connection reliability and connection reliability in the connection structure 1 become high. Note that the conductive paste may contain a flux. When the flux is used, the flux is generally deactivated gradually by heating.

  In addition, in the connection structure 1 shown in FIG. 1, all the solder parts 4A are located in the area | region which the 1st, 2nd electrodes 2a and 3a oppose. The connection structure 1X of the modification shown in FIG. 3 is different from the connection structure 1 shown in FIG. 1 only in the connection portion 4X. The connection part 4X has the solder part 4XA and the hardened | cured material part 4XB. As in the connection structure 1X, most of the solder portions 4XA are located in regions where the first and second electrodes 2a and 3a are opposed to each other, and a part of the solder portion 4XA is first and second. You may protrude to the side from the area | region which electrode 2a, 3a has opposed. The solder part 4XA protruding laterally from the region where the first and second electrodes 2a and 3a are opposed is a part of the solder part 4XA and is not a solder separated from the solder part 4XA. In the present embodiment, the amount of solder away from the solder portion can be reduced, but the solder away from the solder portion may exist in the cured product portion.

  If the usage-amount of electroconductive particle is reduced, it will become easy to obtain the connection structure 1. FIG. If the usage-amount of electroconductive particle is increased, it will become easy to obtain the connection structure 1X.

  From the viewpoint of further improving the conduction reliability, in the connection structures 1 and 1X, the first electrode 2a and the second electrode 2a are arranged in the stacking direction of the first electrode 2a, the connection portions 4 and 4X, and the second electrode 3a. When the portion facing the electrode 3a is viewed, the solder portion in the connection portions 4 and 4X is at least 50% of the area of 100% of the portion facing the first electrode 2a and the second electrode 3a. 4A and 4XA are preferably arranged.

  From the viewpoint of further improving the conduction reliability, the 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 seen. Sometimes, 50% or more (more preferably 60% or more, still more preferably 70% or more, particularly preferably 80% or more) out of 100% of the area where the first electrode and the second electrode face each other. , Most preferably 90% or more), the solder portion in the connection portion is preferably disposed.

  From the viewpoint of further improving the conduction reliability, the first electrode and the second electrode are opposed to each other in a direction orthogonal to the stacking direction of the first electrode, the connection portion, and the second electrode. When the matching portion is viewed, the portion where the first electrode and the second electrode face each other is 70% or more (more preferably 80% or more, more preferably 90%) of the solder portion in the connection portion. In particular, it is preferable that 95% or more, most preferably 99% or more) is disposed.

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

  First, the 1st connection object member 2 which has the 1st 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 conductive particles 11A is disposed on the surface of the first connection target member 2 (first Process). 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 the arrangement of the conductive material 11, the conductive particles 11A are arranged both on the first electrode 2a (line) and on a region (space) where the first electrode 2a is not formed.

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

  Moreover, the 2nd connection object member 3 which has the 2nd 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 opposite to the first connection target member 2 side of the conductive material 11, The 2nd connection object member 3 is arrange | positioned (2nd process). On the surface of the conductive material 11, the second connection target member 3 is disposed from the second electrode 3a side. At this time, the first electrode 2a and the second electrode 3a are opposed to each other.

  Next, the conductive material 11 is heated above the melting point of the conductive particles 11A (third step). Preferably, the conductive material 11 is heated above the curing temperature of the thermosetting component 11B (binder). At the time of this heating, the conductive particles 11A that existed in the region where no electrode is formed gather between the first electrode 2a and the second electrode 3a (self-aggregation effect). In this embodiment, since the conductive material is used instead of the conductive film, the conductive material 11A has a specific composition, so that the conductive particles 11A are formed between the first electrode 2a and the second electrode 3a. Gather effectively in between. In addition, the conductive particles 11A are melted and joined to each other. Further, the thermosetting component 11B is thermoset. As a result, as shown in FIG. 2C, the connection portion 4 that connects the first connection target member 2 and the second connection target member 3 is formed of the conductive material 11. The connection part 4 is formed of the conductive material 11, the solder part 4A is formed by joining the plurality of conductive particles 11A, and the cured part 4B is formed by thermosetting the thermosetting component 11B. If the conductive particles 11A are sufficiently moved, the first electrode 2a and the second electrode 2a are moved after the movement of the conductive particles 11A that are not positioned between the first electrode 2a and the second electrode 3a starts. The temperature does not have to be kept constant until the movement of the conductive particles 11A between the electrodes 3a is completed.

  In the present embodiment, it is preferable that no pressure is applied 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, the conductive particles 11A are effectively collected between the first electrode 2a and the second electrode 3a when the connection portion 4 is formed. In addition, if pressure is applied in at least one of the second step and the third step, the action of the conductive particles trying to collect between the first electrode and the second electrode is inhibited. The tendency to be higher.

  However, pressurization may be performed as long as the interval between the first electrode and the second electrode can be secured. As a means for ensuring the gap between the electrodes, for example, a spacer corresponding to the desired gap between the electrodes may be added so that at least one, preferably three or more spacers are arranged between the electrodes. Examples of the spacer include inorganic particles and organic particles. The spacer is preferably an insulating particle.

  Moreover, in this embodiment, since pressurization is not performed, when the second connection target member is superimposed on the first connection target member to which the conductive material is applied, the electrode of the first connection target member Even when the first connection target member and the second connection target member are overlapped in a state where the alignment of the electrodes of the second connection target member is shifted, the shift is corrected and the first connection target member is corrected. Can be connected to the electrode of the second connection target member (self-alignment effect). This is because the molten solder self-aggregated between the electrode of the first connection target member and the electrode of the second connection target member is the electrode of the first connection target member and the electrode of the second connection target member. As the area where the solder and the other components of the conductive material are in contact with each other is minimized, the energy becomes more stable. Therefore, the force that makes the connection structure with alignment, which is the connection structure with the smallest area, works. Because. At this time, it is desirable that the conductive material is not cured, and that the viscosity of components other than the conductive particles of the conductive material is sufficiently low at that temperature and time.

  In this way, the connection structure 1 shown in FIG. 1 is obtained. The second step and the third step may be performed continuously. Moreover, after performing the said 2nd process, the laminated body of the 1st connection object member 2, the electrically-conductive material 11, and the 2nd connection object member 3 which are obtained is moved to a heating part, and the said 3rd connection object is carried out. You may perform a process. In order to perform the heating, the laminate may be disposed on a heating member, or the laminate may be disposed 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.

  In addition, after the said 3rd process, a 1st connection object member or a 2nd connection object member can be peeled from a connection part for the purpose of correction of a position or re-production. The heating temperature for performing this peeling is preferably not lower than the melting point of the conductive particles, more preferably not lower than the melting point (° C.) of the conductive particles + 10 ° C. The heating temperature for performing this peeling may be the melting point (° C.) of the conductive particles + 100 ° C. or less.

  As the heating method in the third step, a method of heating the entire connection structure using a reflow furnace or an oven above the melting point of the conductive particles and the curing temperature of the thermosetting component, The method of heating only the connection part of a structure locally is mentioned.

  As a tool used for the method of heating locally, a hot plate, a heat gun for applying hot air, a soldering iron, an infrared heater, and the like can be given.

  In addition, when heating locally with a hot plate, the metal directly under the connection is made of a metal with high thermal conductivity, and other places where heating is not preferred are made of a material with low thermal conductivity such as a fluororesin. The upper surface of the hot plate is preferably formed.

  The said 1st, 2nd connection object member is not specifically limited. Specifically as said 1st, 2nd connection object member, electronic components, such as a semiconductor chip, a semiconductor package, LED chip, LED package, a capacitor | condenser, a diode, and a resin film, a printed circuit board, a flexible printed circuit board, flexible Examples include electronic components such as flat cables, rigid flexible substrates, glass epoxy substrates, and circuit boards such as glass substrates. The first and second connection target members are preferably 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. The second connection target member is preferably a resin film, a flexible printed board, a flexible flat cable, or a rigid flexible board. Resin films, flexible printed boards, flexible flat cables, and rigid flexible boards have the property of being highly flexible and relatively lightweight. When a conductive film is used for connection of such a connection object member, there exists a tendency for electroconductive particle to collect on an electrode easily. On the other hand, even if a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible circuit board is used by using a conductive paste, the conductive particles are efficiently collected on the electrode, so that conduction between the electrodes Reliability can be sufficiently increased. When using a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible circuit board, the reliability of conduction between electrodes by not applying pressure compared to the case of using other connection target members such as a semiconductor chip. The improvement effect can be obtained more effectively.

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

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

  Thermosetting compound 1: 2,4-bis (glycidyloxy) benzophenone (crystalline thermosetting compound, melting point: 94 ° C., molecular weight 362)

Synthesis of 2,4-bis (glycidyloxy) benzophenone:
In a three-necked flask, 27 g of 2,4-dihydroxybenzophenone, 230 g of epichlorohydrin, 70 g of n-butanol and 1 g of tetraethylbenzylammonium chloride were added and stirred and dissolved at room temperature. Thereafter, the temperature was raised to 70 ° C. under stirring in a nitrogen atmosphere, and 45 g of an aqueous sodium hydroxide solution (concentration: 48 wt%) was added dropwise under reduced pressure. The dropping was performed over 4 hours. Then, it was made to react at 70 degreeC for 2 hours, using a Dean-Stark tube, removing a water | moisture content. Thereafter, unreacted epichlorohydrin was removed under reduced pressure.

  The obtained reaction product was dissolved in 400 g of a mixed solvent of MEK (methyl ethyl ketone): n-butanol = 3: 1 (weight ratio), and 5 g of an aqueous sodium hydroxide solution (concentration: 10% by weight) was added at 80 ° C. Heated for 2 hours.

  Then, it cooled to room temperature and wash | cleaned with the pure water until the washing | cleaning liquid became neutral. The organic layer was collected by filtration, and the remaining water and the mixed solvent were removed under reduced pressure to obtain a reaction product.

  Using n-hexane, 34 g of the reaction product was purified by recrystallization, and the residual solvent was removed by vacuum drying.

  Obtained epoxy compound: melting point by DSC was 94 ° C., epoxy equivalent was 176 g / eq. According to the mass spectrum, the molecular weight was 362, and the melt viscosity at 150 ° C. was 5 mPa · s.

-Differential scanning calorimetry (DSC) measuring device and measuring conditions Device: “X-DSC7000” manufactured by Hitachi High-Tech Science Co., sample amount: 3 mg, temperature condition: 10 ° C./min

  -Melt viscosity at 150 ° C .: Measured using an ICI cone plate viscometer manufactured by MST Engineering in accordance with ASTM D4287

  ・ Measurement of epoxy equivalent: Measured according to JIS K7236: 2001

  Measurement of molecular weight: Mass spectrum Measured using a GC-MS apparatus (“JMS K-9” manufactured by JEOL Ltd.)

  Thermosetting compound 2: isocyanuric epoxy compound TEPIC-S manufactured by Nissan Chemical Co., Ltd. (melting point 95 ° C., molecular weight 297, epoxy equivalent is 105 g / eq)

  Thermosetting compound 3: Epoxy group-containing acrylic polymer, “MARPROOF G-0150M” manufactured by NOF Corporation

  Thermosetting agent 1: pentaerythritol tetrakis (3-mercaptobutyrate), “Karenz MT PE1” manufactured by Showa Denko KK

  Latent epoxy thermosetting agent 1: “Fujicure 7000” manufactured by T & K TOKA

  Flux 1: glutaric acid, manufactured by Wako Pure Chemical Industries, Ltd., melting point (activation temperature) 95 ° C.

Method for producing solder particles 1 to 5:
Synthesis of polymer 1:
100 g of diethyl adipate, 60 g of 1,6-hexanediol and 0.2 g of dibutyltin oxide as a catalyst were placed in a three-necked flask and reacted at 120 ° C. for 4 hours while dehydrating in a Dean-Stark trap under vacuum conditions. I let you. Then, 100 g of glutaric acid was added and reacted at 120 ° C. for 4 hours. The obtained polymer was washed with pure water and vacuum dried to obtain a polyester having carboxyl groups derived from glutaric acid at both ends. The obtained polymer 1 had a weight average molecular weight of 3000 and a softening point of 60 ° C.

Synthesis of polymer 2:
100 g of ethyl acetate, 5 g of acrylic acid, 20 g of ethyl acrylate, and 45 g of phenyl acrylate were placed in a three-necked flask, and polymerization was carried out for 4 hours with 0.5 g of a radical polymerization initiator under reflux in a nitrogen atmosphere. Thereafter, ethyl acetate and residual monomers were removed by vacuum drying. The obtained polymer 2 had a weight average molecular weight of 10,000 and a softening point of 35 ° C.

Synthesis of polymer 3:
100 g of ethyl acetate, 10 g of n-butyl acrylate, 20 g of ethyl acrylate, and 45 g of phenyl acrylate are placed in a three-necked flask and are refluxed under a nitrogen atmosphere with 0.5 g of a radical polymerization initiator for 4 hours. Polymerization was performed. Thereafter, ethyl acetate and residual monomers were removed by vacuum drying. The obtained polymer 3 had a weight average molecular weight of 15000 and a softening point of 30 ° C.

Synthesis of polymer 4:
A polymer 4 was synthesized in the same manner as the polymer 3 except that the polymerization time was changed to 24 hours. The obtained polymer 4 had a weight average molecular weight of 60,000 and a softening point of 35 ° C.

Synthesis of polymer 5:
Polymer 5 was synthesized in the same manner as polymer 3, except that the polymerization time was changed to 24 hours and the amount of radical polymerization initiator used was changed to 2.5 g. The obtained polymer 5 had a weight average molecular weight of 100,000 and a softening point of 45 ° C.

Solder particles 1:
200 g of SnBi solder particles (“DS-10” manufactured by Mitsui Kinzoku Co., Ltd., melting point 139 ° C., average particle diameter (median diameter) 12 μm), 20 g of polymer 1, 100 g of acetone, hydroxyl groups and polymer on the surface of the solder particles 0.5 g of p-toluenesulfonic acid, which is a dehydration condensation reaction catalyst for carboxyl groups, was added and reacted at 60 ° C. for 5 hours. Thereafter, the solder particles were collected with a filter paper, and the unreacted polymer was removed with acetone. The CV value was 30%. According to cross-sectional observation with TEM, the thickness of polymer 1 of the coating layer was 40 nm.

Solder particles 2:
200 g of SnBi solder particles (“DS-10” manufactured by Mitsui Kinzoku Co., Ltd., melting point 139 ° C., average particle diameter (median diameter) 12 μm), 20 g of polymer 2, 100 g of acetone, hydroxyl groups and polymers on the surface of the solder particles 0.5 g of p-toluenesulfonic acid, which is a dehydration condensation reaction catalyst for carboxyl groups, was added and reacted at 60 ° C. for 5 hours. Thereafter, the solder particles were collected with a filter paper, and the unreacted polymer was removed with acetone. The CV value was 30%. According to the cross-sectional observation with TEM, the thickness of the polymer 2 of the coating layer was 80 nm.

Solder particles 3:
200 g of SnBi solder particles (“DS-10” manufactured by Mitsui Kinzoku Co., Ltd., melting point 139 ° C., average particle diameter (median diameter) 12 μm), 20 g of polymer 3, 100 g of acetone, hydroxyl groups and polymer on the surface of the solder particles 0.5 g of p-toluenesulfonic acid, which is a dehydration condensation reaction catalyst for carboxyl groups, was added and reacted at 60 ° C. for 5 hours. Thereafter, the solder particles were collected with a filter paper, and the unreacted polymer was removed with acetone. The CV value was 30%. According to cross-sectional observation with TEM, the thickness of the polymer 3 of the coating layer was 80 nm.

Solder particles 4:
200 g of SnBi solder particles (“DS-10” manufactured by Mitsui Kinzoku Co., Ltd., melting point 139 ° C., average particle diameter (median diameter) 12 μm), 20 g of polymer 4, 100 g of acetone, hydroxyl groups and polymer on the surface of the solder particles 0.5 g of p-toluenesulfonic acid, which is a dehydration condensation reaction catalyst for carboxyl groups, was added and reacted at 60 ° C. for 5 hours. Thereafter, the solder particles were collected with a filter paper, and the unreacted polymer was removed with acetone. The CV value was 30%. According to the cross-sectional observation with TEM, the thickness of the polymer 4 of the coating layer was 150 nm.

Solder particles 5:
200 g of SnBi solder particles (“DS-10” manufactured by Mitsui Kinzoku Co., Ltd., melting point 139 ° C., average particle diameter (median diameter) 12 μm), 20 g of polymer 5, 100 g of acetone, hydroxyl groups and polymer on the surface of the solder particles 0.5 g of p-toluenesulfonic acid, which is a dehydration condensation reaction catalyst for carboxyl groups, was added and reacted at 60 ° C. for 5 hours. Thereafter, the solder particles were collected with a filter paper, and the unreacted polymer was removed with acetone. The CV value was 30%. According to cross-sectional observation with TEM, the thickness of the polymer 5 of the coating layer was 200 nm.

  Solder particles A: SnBi solder particles (“DS-10” manufactured by Mitsui Kinzoku Co., Ltd., melting point 139 ° C., average particle diameter (median diameter) 12 μm)

(CV value of solder particles)
The CV value was measured with a laser diffraction particle size distribution analyzer (“LA-920” manufactured by Horiba, Ltd.).

(Examples 1 to 10 and Comparative Example 1)
The components shown in Table 1 below were blended in the blending amounts shown in Table 1 below to obtain anisotropic conductive paste.

(2) Production of first connection structure (L / S = 50 μm / 50 μm) Glass epoxy substrate 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 (FR-4 substrate) (first connection target member) was prepared. Moreover, the flexible printed circuit board (2nd connection object member) which has a copper electrode pattern (thickness of a copper electrode 12 micrometers) of L / S 50 micrometers / 50 micrometers and electrode length 3mm on the lower surface was prepared.

  The overlapping area of the glass epoxy substrate and the flexible printed circuit 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, the anisotropic conductive paste immediately after production is applied by screen printing using a metal mask so that the thickness is 100 μm on the electrode of the glass epoxy substrate, and anisotropic conductive A paste layer was formed. Next, the flexible printed circuit board was laminated on the upper surface of the anisotropic conductive paste layer so that the electrodes face each other. At this time, no pressure was applied. The weight of the flexible printed board is added to the anisotropic conductive paste layer. Thereafter, while heating the anisotropic conductive paste layer to 190 ° C., the solder is melted and the anisotropic conductive paste layer is cured at 190 ° C. for 10 seconds to obtain a first connection structure. It was.

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

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

(4) Production of third connection structure (L / S = 100 μm / 100 μm) Glass epoxy substrate having a copper electrode pattern (copper electrode thickness 12 μm) with L / S of 100 μm / 100 μm and electrode length of 3 mm on the upper surface (FR-4 substrate) (first connection target member) was prepared. Moreover, the flexible printed circuit board (2nd connection object member) which has a copper electrode pattern (thickness of copper electrode 12 micrometers) of L / S of 100 micrometers / 100 micrometers and electrode length 3mm on the lower surface was prepared.

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

(Evaluation)
(1) Viscosity The viscosity (η25) at 25 ° C. of the anisotropic conductive paste was measured using an E-type viscometer (“TVE22L” manufactured by Toki Sangyo Co., Ltd.) at 25 ° C. and 5 rpm.

(2) Thickness of solder part By observing a cross section of the obtained first connection structure, the thickness of the solder part between which the upper and lower electrodes are positioned was evaluated.

(3) Solder placement accuracy on electrode 1
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 provided. When viewed, the ratio X of the area where the solder portion in the connection portion is arranged in the area of 100% of the portion where the first electrode and the second electrode face each other was evaluated. The solder placement accuracy 1 on the electrode was determined according to the following criteria.

[Criteria for solder placement accuracy 1 on electrode]
○○: 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%

(4) Solder placement accuracy on electrode 2
In the obtained first, second, and third connection structures, the first electrode and the second electrode are opposed to each other in a direction orthogonal to the stacking direction of the first electrode, the connection portion, and the second electrode. When looking at the mating part, the ratio Y of the solder part in the connecting part arranged in the part where the first electrode and the second electrode face each other in 100% of the solder part in the connecting part was evaluated. . The solder placement accuracy 2 on the electrode was determined according to the following criteria.

[Criteria for solder placement accuracy 2 on electrode]
◯: Ratio Y is 99% or more ○: Ratio Y is 90% or more and less than 99% △: Ratio Y is 70% or more and less than 90% X: Ratio Y is less than 70%

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

[Judgment criteria for conduction reliability]
◯: Average connection resistance is 50 mΩ or less ○: Average connection resistance exceeds 50 mΩ, 70 mΩ or less △: Average connection resistance exceeds 70 mΩ, 100 mΩ or less ×: Average connection resistance exceeds 100 mΩ Or there is a bad connection

(6) Insulation reliability between electrodes adjacent in the lateral direction The obtained first, second and third connection structures (n = 15) were left in an atmosphere of 85 ° C. and 85% humidity for 100 hours. Then, 5V was applied between the electrodes adjacent to the horizontal direction, and the resistance value was measured at 25 locations. Insulation reliability was judged according to the following criteria.

[Criteria for insulation reliability]
◯: Average value of connection resistance is 10 ⁷ Ω or more ○: Average value of connection resistance is 10 ⁶ Ω or more, less than 10 ⁷ Ω △: Average value of connection resistance is 10 ⁵ Ω or more, less than 10 ⁶ Ω ×: Connection The average resistance is less than 10 ⁵ Ω

(7) Position shift between upper and lower electrodes In the obtained first, second, and third connection structures, the first electrode and the second electrode are stacked in the stacking direction of the first electrode, the connection portion, and the second electrode. Whether the center line of the first electrode and the center line of the second electrode were aligned when the portion facing the two electrodes was viewed, and the distance of the positional deviation were evaluated. The positional deviation between the upper and lower electrodes was determined according to the following criteria.

[Criteria for misregistration between upper and lower electrodes]
○: Misalignment is less than 15 μm ○: Misalignment is 15 μm or more and less than 25 μm Δ: Misalignment is 25 μm or more and less than 40 μm ×: Misalignment is 40 μm or more

  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 board were used instead of the flexible printed board.

DESCRIPTION OF SYMBOLS 1,1X ... Connection structure 2 ... 1st connection object member 2a ... 1st electrode 3 ... 2nd connection object member 3a ... 2nd electrode 4, 4X ... Connection part 4A, 4XA ... Solder part 4B, 4XB ... cured material part 11 ... conductive material 11A ... conductive particle 11B ... thermosetting component 21 ... conductive particle 22 ... solder particle 23 ... covering part 31 ... conductive particle 32 ... base particle 33 ... conductive part 33A ... second Conductive part 33B ... solder part 34 ... covering part 41 ... conductive particles 42 ... solder part 43 ... covering part

Claims (11)

Including a plurality of conductive particles and a binder,
The conductive particle has solder on the outer surface portion of the conductive portion, and has a polymer coating portion having a weight average molecular weight of 3000 or more and 100,000 or less on the outer surface of the conductive portion. .   The conductive material according to claim 1, wherein the conductive particles include solder particles and a coating portion of the polymer on an outer surface of the solder particles.   The conductive material according to claim 1, wherein the polymer has a carboxyl group.   The conductive material according to claim 1, wherein the polymer is polyester.   The conductive material according to claim 1, wherein a softening point of the polymer is lower than a melting point of the solder. The binder includes a flux;
The conductive material according to any one of claims 1 to 5, wherein a softening point of the polymer is lower than an activation temperature of the flux.   The conductive material according to claim 1, wherein the polymer is bonded to the solder hydroxyl group by a functional group capable of reacting with the solder hydroxyl group.   The conductive material according to claim 1, wherein the covering portion has a thickness of 0.01 μm or more and 5 μm or less.   The conductive material according to claim 1, wherein an average particle diameter of the conductive particles is 1 μm or more and 60 μm or less.   The conductive material according to claim 1, wherein a content of the conductive particles is 10% by weight or more and 80% by weight or less in 100% by weight of the conductive material. A first connection object member having a first electrode on its surface;
A second connection target member having a second electrode on its surface;
A connection portion connecting the first connection target member and the second connection target member;
The material of the connection part is the conductive material according to any one of claims 1 to 10,
A connection structure in which the first electrode and the second electrode are electrically connected by the conductive particles.

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