JP2015008131A - Conductive material and connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive material which can improve the adhesion between a cured product and a bonding target bonded using the cured product.SOLUTION: A conductive material comprises a conductive particle 1 where at least the conductive external surface is solder, a curable compound, a curing agent, and (meth) acrylic acid. The content of the (meth) acrylic acid in the conductive material 100 wt.% is 0.0001 wt.% or more and 0.1 wt.% or less.

Description

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

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

  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.

  As an example of the anisotropic conductive material, Patent Document 1 below discloses an anisotropic conductive paste for connecting an electronic component and a wiring board. This anisotropic conductive paste has a lead-free solder powder having a melting point of 240 ° C. or less, 10 mass% or more and 50 mass% or less, and a thermosetting resin composition containing an organic acid and 50 mass%. As mentioned above, 90 mass% or less is included. The acid value of the said thermosetting resin composition is 15 mgKOH / g or more and 55 mgKOH / g.

  The following Patent Document 2 discloses a conductive adhesive containing an epoxy adhesive having a flux action and SnBi solder powder.

  Patent Document 3 below discloses a solder paste containing flux and solder particles.

JP 2012-216770 A JP 2006-199937 A JP 05-92296 A

  In the conventional anisotropic conductive materials as described in Patent Documents 1 to 3, the adhesive force between the cured product and the object to be bonded adhered by the cured product may be low.

  An object of the present invention is to provide a conductive material capable of increasing the adhesive force between a cured product and an object to be bonded adhered by the cured product, and to provide a connection structure using the conductive material. is there.

  According to a wide aspect of the present invention, the conductive particles containing at least conductive particles whose outer surface is solder, a curable compound, a curing agent, and (meth) acrylic acid, A conductive material having a content of (meth) acrylic acid of 0.0001% by weight or more and 0.1% by weight or less is provided.

  In a specific aspect of the conductive material according to the present invention, the content of the (meth) acrylic acid in 100% by weight of the conductive material is 0.05% by weight or less.

  In a specific aspect of the conductive material according to the present invention, the content of the (meth) acrylic acid in 100% by weight of the conductive material is 0.005% by weight or more.

  On the specific situation with the electrically-conductive material which concerns on this invention, this electrically-conductive material contains an epoxy (meth) acrylate as said curable compound.

  On the specific situation with the electrically-conductive material which concerns on this invention, this electrically-conductive material is a circuit connection material used for the electrical connection between electrodes.

  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 connecting portion is formed of the conductive material described above, and the first electrode and the second electrode are the conductive particles. To provide a connection structure that is electrically connected.

  The conductive material according to the present invention includes at least conductive particles whose outer surface is conductive is solder, a curable compound, a curing agent, and (meth) acrylic acid, and the above-mentioned in 100% by weight of the conductive material. Since content of (meth) acrylic acid is 0.0001 weight% or more and 0.1 weight% or less, the adhesive force of hardened | cured material and the adhesion target object adhere | attached by this hardened | cured material can be improved.

FIG. 1 is a cross-sectional view schematically showing conductive particles contained in a conductive material according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a modification of the conductive particles. FIG. 3 is a cross-sectional view showing another modification of the conductive particles. FIG. 4 is a front cross-sectional view schematically showing a connection structure using a conductive material according to an embodiment of the present invention. FIG. 5 is a front cross-sectional view schematically showing an enlarged connection portion between conductive particles and electrodes in the connection structure shown in FIG. 4.

  Details of the present invention will be described below.

  The conductive material according to the present invention includes at least conductive particles whose outer surface is conductive is solder, a curable compound, a curing agent, and (meth) acrylic acid. The content of the (meth) acrylic acid in 100% by weight of the conductive material according to the present invention is 0.0001% by weight or more and 0.1% by weight or less.

  By adopting the above-described composition in the present invention, particularly by using a small amount of (meth) acrylic acid, it is possible to increase the adhesive force between the cured material of the conductive material and the bonding object bonded by the cured material. it can. Furthermore, after being exposed to high humidity, the adhesive force between the cured material of the conductive material and the object to be bonded adhered by the cured material can be maintained high.

  Furthermore, by adopting the above-described composition in the present invention, particularly when (meth) acrylic acid is used in a small amount, a change in viscosity can be suppressed during storage of the conductive material. In particular, when the conductive material is a conductive paste, the viscosity change can be effectively suppressed. Further, by adopting the above-described composition in the present invention, particularly by using a small amount of (meth) acrylic acid, the connection resistance can be kept low after being exposed to high humidity.

  The content of the (meth) acrylic acid in 100% by weight of the conductive material according to the present invention may be 0.001% by weight or more. The content of the (meth) acrylic acid in 100% by weight of the conductive material according to the present invention is preferably 0.005% by weight or more. In this case, the adhesive force between the cured product of the conductive material and the object to be bonded adhered by the cured product can be further increased, and after being exposed to high humidity, the cured product of the conductive material The adhesive force with the object to be bonded bonded by the cured product can be maintained even more effectively.

  The content of the (meth) acrylic acid in 100% by weight of the conductive material according to the present invention is preferably 0.05% by weight or less. When the content of the (meth) acrylic acid is 0.05% by weight or less, the adhesive force between the cured product and the bonding object is further increased, and the viscosity change is further suppressed during storage of the conductive material, Furthermore, after being exposed to high humidity, the connection resistance can be more effectively kept low.

  The acid value of the conductive material is preferably 0.01 mgKOH / g or more, more preferably 0.02 mgKOH / g or more, preferably 10 mgKOH / g or less, more preferably 3 mgKOH / g or less. When the acid value is not less than the above lower limit and not more than the above upper limit, both excellent reaction rate and excellent flux effect can be achieved at a higher level.

  The above (meth) acrylic acid may be contained as an impurity in a component when mixing each component (such as a curable compound and a curing agent), and is blended separately from each component (such as a curable compound and a curing agent) ( It may be added later).

  The conductive material according to the present invention is preferably a conductive material that can be cured by heating. In this case, the solder on the conductive outer surface of the conductive particles can be melted by heat when the conductive material is cured by heating. The conductive material according to the present invention may be a conductive material that can be cured by both light irradiation and heating. In this case, the conductive material can be semi-cured (B-staged) by light irradiation to reduce the fluidity of the conductive material, and then the conductive material can be cured by heating.

  Hereinafter, first, each component contained in the conductive material according to the present invention and each component preferably contained will be described in detail.

(Curable compound)
The curable compound is not particularly limited as long as it can be cured by the action of the curing agent. The curable compound is a compound different from (meth) acrylic acid. As for the said sclerosing | hardenable compound, only 1 type may be used and 2 or more types may be used together.

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

  Examples of the curable compound having an unsaturated double bond include a curable compound having a vinyl group or a (meth) acryloyl group. From the viewpoint of easily controlling the curing of the conductive material or further enhancing the conduction reliability in the connection structure, the curable compound having an unsaturated double bond is a cured product having a (meth) acryloyl group. It is preferable that it is an ionic compound. By using the curable compound having the (meth) acryloyl group, it becomes easy to control the curing rate within a suitable range in the entire B-staged conductive material, and the conduction reliability in the obtained connection structure is further increased. Get higher.

  From the viewpoint of easily controlling the cure rate of the B-staged conductive material and further enhancing the conduction reliability of the resulting connection structure, the curable compound having the (meth) acryloyl group is (meth) acryloyl. It is preferable to have one or two groups.

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

  The curable compound may be an epoxy compound (a curable compound having an epoxy group). The epoxy compound may be a compound having an epoxy group at the terminal, such as a phenoxy resin, and the compound may be an oligomer or a polymer.

  When the (meth) acrylic acid and the epoxy compound are reacted to obtain an epoxy (meth) acrylate, the (meth) acrylic acid may remain as an impurity. However, when using epoxy (meth) acrylate mixed with (meth) acrylic acid as an impurity, the content of (meth) acrylic acid in 100% by weight of the obtained conductive material is 0.0001% by weight or more, It is necessary to control to 0.1% by weight or less. Therefore, it is preferable that a large amount of (meth) acrylic acid is not mixed in the epoxy (meth) acrylate. When a large amount of (meth) acrylic acid is contained after the synthesis of the epoxy (meth) acrylate, it is preferable to purify and remove some or all of the (meth) acrylic acid and use the epoxy (meth) acrylate.

  From the viewpoint of further increasing the adhesive force between the cured product and the object to be bonded, the conductive material preferably contains epoxy (meth) acrylate. The epoxy (meth) acrylate is a compound in which all of the epoxy groups are converted to a (meth) acryloyl group (a compound in which a reaction for introducing a (meth) acryl group into all of the epoxy groups is performed). The epoxy (meth) acrylate may be a compound having an epoxy group at the terminal, such as a phenoxy resin, and the compound may be an oligomer or a polymer.

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

  The curable compound having an unsaturated double bond may be a crosslinkable compound or a non-crosslinkable compound.

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

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

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

  Examples of the curable compound having an epoxy group include resorcinol type epoxy compounds, naphthalene type epoxy compounds, anthracene type epoxy compounds, bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, cresol novolac type epoxy compounds, phenol novolac type epoxy compounds, Glycidyl ester type epoxy compound obtained by reacting polybasic acid compound having aromatic skeleton and epichlorohydrin, glycidyl ether type epoxy compound having aromatic skeleton, 2- (3,4-epoxy) cyclohexyl-5 , 5-spiro- (3,4-epoxy) cyclohexane-m-dioxane, 3,4-epoxycyclohexenylmethyl-3 ′, 4′-epoxycyclohexenecarboxylate, dicyclopentadienedio Sid, vinylcyclohexene monooxide, 1,2-epoxy-4-vinylcyclohexane, 1,2: 8,9-diepoxylimonene, ε-caprolactone modified tetra (3,4-epoxycyclohexylmethyl) butanetetracarboxylate, 2 1,2-epoxy-4- (2-oxiranyl) cyclohexane adduct of 2-bis (hydroxymethyl) -1-butanol and the like.

  In 100% by weight of the conductive material, the content of the curable compound having an unsaturated double bond is preferably 10% by weight or more, more preferably 20% by weight or more, preferably 50% by weight or less, more preferably 40% by weight. % Or less.

  The content of the curable compound having an epoxy group in 100% by weight of the conductive material is preferably 10% by weight or more, more preferably 20% by weight or more, preferably 50% by weight or less, more preferably 40% by weight or less. is there.

  In 100% by weight of the conductive material, the total content of the curable compound is preferably 30% by weight or more, more preferably 40% by weight or more, preferably 90% by weight or less, more preferably 60% by weight or less.

(Curing agent)
The conductive material includes a curing agent. As for the said hardening | curing agent, only 1 type may be used and 2 or more types may be used together.

  The curing agent for the curable compound having an unsaturated double bond may be a light or thermal radical polymerization initiator.

  The light or thermal radical polymerization initiator generates radical species by light irradiation or heating. The light or thermal radical polymerization initiator advances the curing of the curable compound having a radical polymerizable group. The light or thermal radical polymerization initiator is not particularly limited. As the light or thermal radical polymerization initiator, a conventionally known light or thermal radical polymerization initiator can be used. The light or thermal radical polymerization initiator may be a photo radical polymerization initiator or a thermal radical polymerization initiator. As for the said photoradical initiator, only 1 type may be used and 2 or more types may be used together.

  The photo radical polymerization initiator is not particularly limited, and includes acetophenone photo radical polymerization initiator, benzophenone photo radical polymerization initiator, thioxanthone, ketal photo radical polymerization initiator, halogenated ketone, acyl phosphinoxide, and acyl phosphonate. Is mentioned.

  Specific examples of the acetophenone photoradical polymerization initiator include 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, Examples include methoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, and 2-hydroxy-2-cyclohexylacetophenone. Specific examples of the ketal radical photopolymerization initiator include benzyl dimethyl ketal.

  The thermal radical polymerization initiator is not particularly limited, and examples thereof include azo compounds and organic peroxides. Examples of the organic peroxide include diacyl peroxide compounds, peroxy ester compounds, hydroperoxide compounds, peroxydicarbonate compounds, peroxyketal compounds, dialkyl peroxide compounds, and ketone peroxide compounds.

  Examples of the azo compound include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 1 , 1′-azobis-1-cyclohexanecarbonitrile, dimethyl-2,2′-azobisisobutyrate, dimethyl-2,2′-azobis (2-methylpropionate), dimethyl-1,1′-azobis (1-cyclohexanecarboxylate), 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-amidinopropane) dihydrochloride, 2-tert-butylazo-2-cyanopropane, 2 2,2′-azobis (2-methylpropionamide) dihydrate, 2,2′-azobis (2,4,4-trimethylpentane), and the like.

  Examples of the diacyl peroxide compound include benzoyl peroxide, diisobutyryl peroxide, di (3,5,5-trimethylhexanoyl) peroxide, dilauroyl peroxide, and disuccinic acid peroxide. Examples of the peroxyester compound include cumylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, tert-hexylperoxyneodecanoate, and tert-butylperoxyneo. Decanoate, tert-butylperoxyneoheptanoate, tert-hexylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2,5-dimethyl-2 , 5-di (2-ethylhexanoylperoxy) hexane, tert-hexylperoxy-2-ethylhexanoate, tert-butylperoxypivalate, tert-butylperoxy-2-ethylhexanoate, tert -Butyl peroxyisobutyrate, tert-butyl per Kishiraureto, tert- butylperoxy isophthalate, tert- butylperoxy acetate, tert- butylperoxy octoate and tert- butyl peroxybenzoate, and the like. Examples of the hydroperoxide compound include cumene hydroperoxide and p-menthane hydroperoxide. Examples of the peroxydicarbonate compound include di-sec-butyl peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, di-n-propyl peroxydicarbonate, diisopropyl peroxycarbonate, and di- (2-ethylhexyl) peroxycarbonate and the like. Other examples of the peroxide include methyl ethyl ketone peroxide, potassium persulfate, and 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane.

  The decomposition temperature for obtaining the 10-hour half-life of the thermal radical polymerization initiator is preferably 30 ° C. or higher, more preferably 40 ° C. or higher, preferably 90 ° C. or lower, more preferably 80 ° C. or lower. When the decomposition temperature for obtaining the 10-hour half-life of the thermal radical polymerization initiator is less than 30 ° C., the storage stability of the curable composition tends to be lowered. It tends to be difficult to sufficiently heat-cure the composition.

  The content of the light or thermal radical polymerization initiator is not particularly limited. The content of the light or thermal radical polymerization initiator with respect to 100 parts by weight of the curable compound is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, preferably 10 parts by weight or less. More preferably, it is 5 parts by weight or less. The content of the light or thermal radical polymerization initiator is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight with respect to 100 parts by weight of the curable compound having an unsaturated double bond. The amount is preferably 10 parts by weight or less, more preferably 5 parts by weight or less. When the content of the light or thermal radical curing agent is not less than the above lower limit and not more than the above upper limit, the fast curability of the composition and the moist heat resistance of the cured product are improved in a well-balanced manner.

  Examples of the curing agent for the curable compound having an epoxy group include an imidazole curing agent, an amine curing agent, a phenol curing agent, a polythiol curing agent, a cation generator, and an acid anhydride. Among these, an imidazole curing agent, a polythiol 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 polythiol curing agent or a latent amine curing agent. Only 1 type may be used for these hardening | curing agents, and 2 or more types may be used together. In addition, the said hardening | curing 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 polythiol 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 cation generator 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.

  From the viewpoint of further enhancing the flux effect, the curing agent preferably contains a cation generator. The conductive material preferably contains a cation generator.

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

  When the curing agent contains a cation generator, the content of the cation generator is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight with respect to 100 parts by weight of the curable compound. The amount is preferably 10 parts by weight or less, more preferably 5 parts by weight or less. When the content of the cation generator is not less than the above lower limit and not more than the above upper limit, the conductive material is sufficiently cured.

(flux)
The conductive material preferably contains a flux. The use of the flux makes it difficult to form an oxide film on the solder surface, and the oxide film formed on the solder surface or electrode surface can be effectively removed. As a result, the conduction reliability in the connection structure is further increased. Note that the conductive material does not necessarily include a flux.

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

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

The rosin is a rosin composed mainly of abietic acid. The flux is preferably a rosin, and more preferably abietic acid. By using this preferable flux, the connection resistance between the electrodes is further reduced. The flux is preferably an organic acid having a carboxyl group. Examples of the compound having a carboxyl group include a compound having a carboxyl group bonded to an alkyl chain and a compound having a carboxyl group bonded to an aromatic ring. In these compounds having a carboxyl group, a hydroxyl group may be further bonded to an alkyl chain or an aromatic ring. The number of carboxyl groups bonded to the alkyl chain or aromatic ring is preferably 1 to 3, more preferably 1 or 2. The number of carbon atoms in the alkyl chain in the compound in which a carboxyl group is bonded to the alkyl chain is preferably 3 or more, preferably 8 or less, more preferably 6 or less. Specific examples of the compound in which the carboxyl group is bonded to the alkyl chain include hexanoic acid (CH ₃ (CH ₂ ) ₄ COOH), heptanoic acid (CH ₃ (CH ₂ ) ₅ COOH), glutaric acid (HOOC (CH ₂ ) ₃ COOH), adipic acid (HOOC (CH ₂ ) ₄ COOH), pimelic acid (HOOC (CH ₂ ) ₅ COOH), and the like. Specific examples of the compound having a carboxyl group and a hydroxyl group include malic acid and citric acid. Specific examples of the compound having a carboxyl group bonded to an aromatic ring include benzoic acid, phthalic acid, benzoic anhydride, and phthalic anhydride.

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

  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, and more preferably 25% by weight or less. When the content of the flux is not less than the above lower limit and not more than the above upper limit, it becomes more difficult to form an oxide film on the solder surface, and the oxide film formed on the solder surface or electrode surface is further effectively removed. it can. Further, when the content of the flux is equal to or more than the lower limit, the effect of adding the flux is more effectively expressed. When the content of the flux is not more than the above upper limit, the hygroscopic property of the cured product is further lowered, and the reliability of the connection structure is further enhanced.

(Conductive particles)
The conductive particles are not particularly limited as long as at least the conductive outer surface is solder. The conductive particles are preferably conductive particles having base particles and a conductive layer disposed on the surface of the base particles, and at least an outer surface of the conductive layer being a solder layer. Examples of the substrate particles include resin particles, inorganic particles excluding metal particles, organic-inorganic hybrid particles, and metal particles. The base particles may be core-shell particles. The substrate particles are preferably substrate particles that are not metal particles, and more preferably resin particles, inorganic particles excluding metal particles, or organic-inorganic hybrid particles. The substrate particles are preferably resin particles formed of a resin. When connecting the electrodes, the conductive particles are generally compressed after the conductive particles are arranged between the electrodes. When the substrate particles are resin particles, the conductive particles are easily deformed by compression, and the contact area between the conductive particles and the electrode is increased. For this reason, the conduction | electrical_connection reliability between electrodes can be improved. From the viewpoint of further improving the thermal shock resistance in the connection structure, the conductive particles include resin particles and a conductive layer disposed on the surface of the resin particles, and at least the outer surface of the conductive layer is soldered. The layer is preferably a conductive particle.

  In FIG. 1, the electroconductive particle contained in the electrically-conductive material which concerns on one Embodiment of this invention is typically shown with sectional drawing.

  A conductive particle 1 shown in FIG. 1 includes resin particles 2 and a conductive layer 3 disposed on the surface 2 a of the resin particles 2. The conductive layer 3 covers the surface 2 a of the resin particle 2. The conductive particle 1 is a coated particle in which the surface 2 a of the resin particle 2 is coated with the conductive layer 3. Accordingly, the conductive particles 1 have the conductive layer 3 on the surface 1a.

  The conductive layer 3 includes a first conductive layer 4 disposed on the surface 2a of the resin particle 2, and a solder layer 5 (second conductive layer) disposed on the surface 4a of the first conductive layer 4. Have The outer surface layer of the conductive layer 3 is a solder layer 5. Accordingly, the conductive particle 1 has the solder layer 5 as a part of the conductive layer 3 (conductive part), and further, as a part of the conductive layer 3 (conductive part) between the resin particle 2 and the solder layer 5. A first conductive layer 4 is provided separately from the solder layer 5. Thus, the conductive layer 3 may have a multilayer structure, or may have a laminated structure of two or more layers.

  As described above, the conductive layer 3 has a two-layer structure. As in the modification shown in FIG. 2, the conductive particles 11 may have a solder layer 12 as a single conductive layer. The at least outer surface of the conductive part in the conductive particles may be solder, and for example, it is preferable that at least the outer surface layer of the conductive layer in the conductive particles is a solder layer. However, the conductive particles 1 are preferable among the conductive particles 1 and the conductive particles 11 because the conductive particles can be easily produced. In addition, as in the modification shown in FIG. 3, solder particles 16 that are not core-shell particles and do not have base particles in the core may be used. The solder particles 16 are formed of solder at both the central portion and the outer surface. However, among the conductive particles 1, the conductive particles 11, and the solder particles 16, the conductive particles 1 and the conductive particles 11 are preferable.

  The conductive particles are more preferably solder particles. When the conductive particles are solder particles, the electrical conductivity and heat and humidity resistance can be improved, and the adhesive force between the cured product and the object to be bonded adhered by the cured product can be further enhanced.

  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; Alkylene terephthalate, polycarbonate, polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polysulfone, polyphenylene Oxide, polyacetal, polyimide, polyamideimide, polyether ether Tons, polyethersulfone, and polymers such as obtained by a variety of polymerizable monomer having an ethylenically unsaturated group is polymerized with one or more thereof. Resin for forming the resin particles can be designed and synthesized, and the hardness of the base particles can be easily controlled within a suitable range, which is suitable for conductive materials and having physical properties at the time of compression. Is preferably a polymer obtained by polymerizing one or more polymerizable monomers having a plurality of ethylenically unsaturated groups.

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

  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) acrylates such as meth) acrylate and isobornyl (meth) acrylate; oxygen such as 2-hydroxyethyl (meth) acrylate, glycerol (meth) acrylate, polyoxyethylene (meth) acrylate and glycidyl (meth) acrylate (Meth) acrylates; nitrile-containing monomers such as (meth) acrylonitrile; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether; vinyl acids such as vinyl acetate, vinyl butyrate, vinyl laurate, vinyl stearate Esters; 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 Is mentioned.

  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) acrylates such as acrylate, (poly) tetramethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate; triallyl (iso) cyanure Silane-containing monomers such as triallyl trimellitate, divinylbenzene, diallyl phthalate, diallylacrylamide, diallyl ether, γ- (meth) acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, vinyltrimethoxysilane It is done.

  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 particles, examples of the inorganic material for forming the substrate particles include silica and carbon black. This inorganic substance is preferably not a metal. The particles formed by 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.

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

  The average particle diameter of the substrate particles is preferably 1 μm or more, more preferably 2 μm or more, preferably 100 μm or less, more preferably 50 μm or less, still more preferably 30 μm or less, and particularly preferably 5 μm or less. When the average particle diameter of the substrate particles is equal to or more than the above lower limit, the conduction reliability between the electrodes is further enhanced. The space | interval between electrodes can be narrowed as the average particle diameter of a base particle is below the said upper limit.

  The method for forming a conductive layer on the surface of the base particle and the method for forming a solder layer on the surface of the base particle or the surface of the first conductive layer are not particularly limited. As a method of forming the conductive layer and the solder layer, for example, a method by electroless plating, a method by electroplating, a method by physical collision, a method by mechanochemical reaction, a method by physical vapor deposition or physical adsorption, And a method of coating the surface of the 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 method of forming the solder layer on the surface of the base particle or the first conductive layer is preferably a method by physical collision. It is preferable that the solder layer is disposed on the surface of the base particle or the first conductive layer by physical impact.

  The material constituting the solder (solder layer) is preferably a filler material having a liquidus of 450 ° C. or less based on JIS Z3001: Welding terms. Examples of the solder composition include metal compositions containing zinc, gold, 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.

  The melting point of the solder (solder layer) is preferably 80 ° C. or higher, more preferably 100 ° C. or higher, preferably 200 ° C. or lower, more preferably 160 ° C. or lower, still more preferably 150 ° C. or lower, still more preferably 140 ° C. or lower. It is. The melting point of the solder (solder layer) is more preferably 100 ° C. or higher and 140 ° C. or lower.

  In order to further increase the bonding strength between the solder (solder layer) and the electrode, the solder is nickel, copper, antimony, aluminum, zinc, iron, gold, titanium, phosphorus, germanium, tellurium, cobalt, bismuth, manganese. Further, it may contain a metal such as chromium, tungsten, molybdenum and palladium. From the viewpoint of further increasing the bonding strength between the solder and the electrode, the solder preferably contains nickel, copper, antimony, aluminum, or zinc. From the viewpoint of further increasing the bonding strength between the solder and the electrode, the content of these metals for increasing the bonding strength is preferably 0.0001% by weight or more in 100% by weight of the solder (solder layer). Is 1% by weight or less.

  The conductive particles include base particles and a conductive layer disposed on the surface of the base particles, and the outer surface of the conductive layer is a solder layer, and the base particles and the solder layer The first conductive layer is preferably provided separately from the solder layer. In this case, the solder layer is a part of the whole conductive layer, and the first conductive layer is a part of the whole conductive layer.

  The first conductive layer different from the solder layer preferably contains a metal. The metal constituting the first conductive layer is not particularly limited. Examples of the metal include gold, silver, copper, platinum, palladium, zinc, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, tungsten, molybdenum and cadmium, and alloys thereof. Is mentioned. 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 first conductive layer 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 layers for the connection between the electrodes, the connection resistance between the electrodes is further reduced. In addition, a solder layer can be more easily formed on the surface of these preferable conductive layers. The first conductive layer may be a solder layer. The conductive particles may have a plurality of solder layers.

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

  In 100% by weight of the solder and the solder layer, the content of tin is preferably less than 90% by weight, more preferably 85% by weight or less. Further, the content of tin in 100% by weight of the solder and the solder layer is appropriately determined in consideration of the melting point of the solder and the solder layer. The content of tin in 100% by weight of the solder and solder layer is preferably 5% by weight or more, more preferably 10% by weight or more, and still more preferably 20% by weight or more.

  The thicknesses of the first conductive layer and the solder layer are each preferably 10 nm or more, more preferably 50 nm or more, still more preferably 100 nm or more, preferably 2000 nm or less, more preferably 1000 nm or less. When the thickness of the first conductive layer and the solder layer is not less than the above lower limit, the conductivity is sufficiently high. When the thickness of the first conductive layer and the solder layer is not more than the above upper limit, the difference in coefficient of thermal expansion between the base particles and the first conductive layer and the solder layer is reduced, and the first conductive layer and the solder layer Peeling is less likely to occur.

  The first conductive layer may have a stacked structure of two or more layers. When the first conductive layer has a laminated structure of two or more layers, the thickness of the outermost layer in the first conductive layer is preferably 5 nm or more, more preferably 10 nm or more, still more preferably 25 nm or more, and particularly preferably Is 50 nm or more, preferably 1000 nm or less, more preferably 500 nm or less. When the thickness of the outermost layer in the first conductive layer is not less than the above lower limit, the conductivity is sufficiently high. When the thickness of the outermost layer in the first conductive layer is not more than the above upper limit, the difference in thermal expansion coefficient between the base particles and the outermost layer of the first conductive layer is reduced, and the outermost layer of the first conductive layer Peeling is less likely to occur.

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

  The resin particles can be properly used depending on the electrode size or land diameter of the substrate to be mounted.

  From the viewpoint of more reliably connecting the upper and lower electrodes and further suppressing the short circuit between the electrodes adjacent in the lateral direction, the ratio of the average particle diameter C of the conductive particles to the average particle diameter A of the resin particles ( C / A) is more than 1.0, preferably 3.0 or less. When the first conductive layer is between the resin particles and the solder layer, the ratio of the average particle diameter B of the conductive particle portion excluding the solder layer to the average particle diameter A of the resin particles (B / A) is greater than 1.0, preferably 2.0 or less. Further, when there is the first conductive layer between the resin particles and the solder layer, the average particle diameter B of the conductive particle portion excluding the solder layer having the average particle diameter C of the conductive particles including the solder layer. The ratio (C / B) to is more than 1.0, preferably 2.0 or less. When the ratio (B / A) is within the above range or the ratio (C / B) is within the above range, electrodes that are more reliably connected between the upper and lower electrodes and that are adjacent in the lateral direction The short circuit between them can be further suppressed.

Conductive materials for FOB and FOF applications:
The conductive material according to the present invention is suitably used for connection between a flexible printed circuit board and a glass epoxy board (FOB (Film on Board)) or connection between a flexible printed circuit board and a flexible printed circuit board (FOF (Film on Film)). It is done.

  In FOB and FOF applications, L & S, which is the size of a portion (line) with an electrode and a portion (space) without an electrode, is generally 100 to 500 μm. The average particle diameter of the resin particles used for FOB and FOF applications is preferably 10 to 100 μm. When the average particle diameter of the resin particles is 10 μm or more, the thickness of the conductive material and the connection portion disposed between the electrodes is sufficiently increased, and the adhesive force is further increased. When the average particle diameter of the resin particles is 100 μm or less, a short circuit is more unlikely to occur between adjacent electrodes.

Conductive materials for flip chip applications:
The conductive material according to the present invention is suitably used for flip chip applications.

  For flip chip applications, the land diameter is generally 15-80 μm. The average particle size of the resin particles used for flip chip applications is preferably 1 to 15 μm. When the average particle diameter of the resin particles is 1 μm or more, the thickness of the solder layer disposed on the surface of the resin particles can be sufficiently increased, and the electrodes can be more reliably electrically connected. it can. When the average particle diameter of the resin particles is 15 μm or less, a short circuit is more unlikely to occur between adjacent electrodes.

Conductive materials for COF:
The conductive material according to the present invention is suitably used for connection between a semiconductor chip and a flexible printed board (COF (Chip on Film)).

  In a COF application, L & S, which is a dimension between a portion (line) with an electrode and a portion (space) without an electrode (space), is generally 10 to 50 μm. The average particle diameter of the resin particles used for COF applications is preferably 1 to 10 μm. When the average particle diameter of the resin particles is 1 μm or more, the thickness of the solder layer disposed on the surface of the resin particles can be sufficiently increased, and the electrodes can be more reliably electrically connected. it can. When the average particle diameter of the resin particles is 10 μm or less, a short circuit is more unlikely to occur between adjacent electrodes.

  The “average particle diameter” of the base material particles (the resin particles and the like) and the conductive particles indicates a number average particle diameter. The average particle diameter of the substrate particles (resin particles and the like) and the conductive particles is obtained by observing 50 arbitrary conductive particles with an electron microscope or an optical microscope and calculating an average value.

  In 100% by weight of the conductive material, the content of the conductive particles is preferably 3% by weight or more, and preferably 40% by weight or less. When the content of the conductive particles is 3% by weight or more and 40% by weight or less, both conductivity and insulation can be achieved at a higher level when performing anisotropic conductive connection. . In 100% by weight of the conductive material, the content of the conductive particles is preferably 5% by weight or more, more preferably 10% by weight or more, still more preferably 15% by weight or more, preferably 35% by weight or less, more preferably 30% by weight or less. When the content of the conductive particles in 100% by weight of the conductive material is not less than the above lower limit and not more than the above upper limit, the conductive particles can be easily disposed between the upper and lower electrodes to be connected. Furthermore, it becomes difficult to electrically connect adjacent electrodes that should not be connected via a plurality of conductive particles. That is, a short circuit between adjacent electrodes can be further prevented.

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

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

  From the viewpoint of further improving the adhesion reliability of the object to be bonded, it is preferable that the conductive material contains an adhesion-imparting agent. Examples of the adhesion-imparting agent include a coupling agent and a flexible material. As for the said adhesion imparting agent, only 1 type may be used and 2 or more types may be used together.

  In 100% by weight of the conductive material, the content of the adhesion-imparting agent is preferably 0.1% by weight or more, more preferably 1% by weight or more, preferably 10% by weight or less, more preferably 5% by weight or less. When the content of the adhesion-imparting agent is not less than the above lower limit and not more than the above upper limit, the adhesion reliability of the bonding object is further increased.

(Details and applications of conductive materials)
The conductive material according to the present invention is a paste-like or film-like conductive material, and is preferably a paste-like conductive material. The paste-like conductive material is a conductive paste. The film-like conductive material is a conductive film. When the conductive material is a conductive film, a film that does not include conductive particles may be laminated on the conductive film that includes conductive particles. The conductive material according to the present invention is preferably an anisotropic conductive material. The conductive material according to the present invention is preferably used for connection between electrodes, is preferably a circuit connection material, and more preferably is a circuit connection material used for electrical connection between electrodes.

  The conductive material according to the present invention is a conductive paste, and is preferably a conductive paste applied on a connection target member in a paste state.

  The viscosity of the conductive paste at 25 ° C. is preferably 3 Pa · s or more, more preferably 5 Pa · s or more, preferably 600 Pa · s or less, more preferably 400 Pa · s or less. When the viscosity is equal to or higher than the lower limit, sedimentation of conductive particles in the conductive paste can be suppressed. When the viscosity is equal to or lower than the upper limit, the dispersibility of the conductive particles is further increased. If the viscosity of the conductive paste before coating is within the above range, after applying the conductive paste on the first connection target member, the flow of the conductive paste before curing can be further suppressed, and the voids are further reduced. It becomes difficult to occur. The paste form includes liquid.

  The conductive material according to the present invention is preferably a conductive material used for connecting a connection target member having a copper electrode. When a connection target member having a copper electrode is connected using a conductive material, there is a problem that migration is likely to occur due to the copper electrode in the connection structure. On the other hand, by using the conductive material according to the present invention, even if a connection target member having a copper electrode is connected, migration in the connection structure can be effectively suppressed, and insulation reliability can be effectively increased. it can.

  The conductive material according to the present invention can be used for bonding various connection target members. The conductive material is preferably used for obtaining a connection structure in which the first and second connection target members are electrically connected.

  The connection structure according to the present invention includes a first connection target member having a first electrode on the surface, a second connection target member having a second electrode on the surface, and the first and second connection targets. A connecting portion for connecting members, wherein the connecting portion is formed of the conductive material described above, and the first electrode and the second electrode are electrically connected by the conductive particles. ing.

  FIG. 4 is a front sectional view schematically showing a connection structure using a conductive material according to an embodiment of the present invention.

  The connection structure 21 shown in FIG. 4 includes a first connection target member 22, a second connection target member 23, and a connection portion that electrically connects the first and second connection target members 22 and 23. 24. The first connection target member 22 and the second connection target member 23 are electronic components. The connection part 24 is formed of a conductive material including the conductive particles 1. In FIG. 4, the conductive particles 1 are schematically shown for convenience of illustration.

  The first connection target member 22 has a plurality of first electrodes 22b on the surface 22a (upper surface). The second connection target member 23 has a plurality of second electrodes 23b on the surface 23a (lower surface). The first electrode 22 b and the second electrode 23 b are electrically connected by one or a plurality of conductive particles 1. Accordingly, the first and second connection target members 22 and 23 are electrically connected by the conductive particles 1.

The manufacturing method of the connection structure is not particularly limited. As an example of the manufacturing method of the connection structure, the conductive material is disposed between the first connection target member and the second connection target member to obtain a multilayer body, and then the multilayer body is heated. And a method of applying pressure. The solder layer of the conductive particles 1 is melted by heating and pressurization, and the electrodes are electrically connected by the conductive particles 1. Further, when the binder resin contains a thermosetting compound, the binder resin is cured, and the first and second connection target members 22 and 23 are connected by the cured binder resin. The pressure of the pressurization is about 9.8 × 10 ^{4 to} 4.9 × 10 ⁶ Pa. The temperature of the said heating is about 120-220 degreeC.

  FIG. 5 is an enlarged front sectional view schematically showing a connection portion between the conductive particle 1 and the first and second electrodes 22b and 23b in the connection structure 21 shown in FIG. As shown in FIG. 5, in the connection structure 21, after the solder layer 5 in the conductive particles 1 is melted by heating and pressurizing the laminate, the melted solder layer portions 5a are first and second. It is in sufficient contact with the electrodes 22b and 23b. That is, by using the conductive particles 1 whose surface layer is the solder layer 5, the conductive particles are compared with the case where the surface layer of the conductive layer is a metal such as nickel, gold or copper. 1 and the contact area between the electrodes 22b and 23b increase. For this reason, the conduction | electrical_connection reliability of the connection structure 21 becomes high. In general, the flux is gradually deactivated by heating.

  If the said 1st, 2nd connection object member is an electronic component, it will not specifically limit. Specifically, the first and second connection target members include electronic components such as semiconductor chips, capacitors, and diodes, and circuit boards such as printed boards, flexible printed boards, glass epoxy boards, and glass boards. Examples include parts. The conductive material is preferably a conductive material used for connecting electronic components. The conductive material according to the present invention is preferably used for electrical connection of electrodes of electronic components.

  In the connection structure, 1/5 or more of the total area of the connection portion between the connection portion and the first connection target member, and the connection portion between the connection portion and the second connection target member, It is preferable that they are connected by components other than the conductive particles contained in the conductive material. In other words, in the connection structure, 1/5 of the total area of the connection portion between the connection portion and the first connection target member and the connection portion between the connection portion and the second connection target member. It is preferable that less than are connected by the conductive particles contained in the conductive material. In this case, the thermal shock resistance of the connection structure is further enhanced.

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

  It is preferable that at least one of the first electrode and the second electrode is a copper electrode. Both the first electrode and the second electrode are preferably copper electrodes. In this case, the flux effect by the conductive material according to the present invention is further obtained, and the conduction reliability in the connection structure is further increased.

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

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

(Mixture of curable compound and (meth) acrylic acid)
(1) Synthesis of a first reaction product of bisphenol F and 1,6-hexanediol diglycidyl ether:
72 parts by weight of bisphenol F (containing 4,4′-methylene bisphenol, 2,4′-methylene bisphenol and 2,2′-methylene bisphenol at a weight ratio of 31:52:17), 1,6-hexanediol 100 parts by weight of glycidyl ether and 1 part by weight of triphenylphosphine were placed in a three-necked flask and dissolved at 150 ° C. Thereafter, the first reaction product was obtained by addition polymerization at 180 ° C. for 6 hours.

  After confirming that the addition polymerization reaction has progressed, the first reaction product has a structural unit in which the skeleton derived from bisphenol F and the skeleton derived from 1,6-hexanediol diglycidyl ether are bonded to the main chain. And having an epoxy group derived from 1,6-hexanediol diglycidyl ether at both ends was confirmed.

  100 parts by weight of the obtained first reactant and 4 parts by weight of acrylic acid were blended, and the temperature was raised to 80 ° C. After raising the temperature, 0.1 part by weight of tetra-n-butylsulfonium bromide, which is a reaction catalyst for the epoxy group and carboxyl group, is added and subjected to a condensation reaction for 4 hours. Compound 2 in which the carboxyl group was reacted was obtained. The weight average molecular weight of the epoxy compound obtained by GPC was 8,000.

  The obtained compound 2 was applied on a PET film so as to have a thickness of about 100 μm, and vacuum dried at 60 ° C. for 24 hours under reduced pressure of 100 Pa to remove acrylic acid. When the remaining amount of acrylic acid was measured by NMR, it was 0.01% by weight.

  Compound 3 having methacrylic groups at both ends was obtained in the same manner except that methacrylic acid was reacted with the first reactant. Similarly, when the remaining amount of meacrylic acid was measured by NMR, it was 0.01% by weight.

(Curable compound)
Bisphenol F type epoxy compound ("EXA830-CRP" manufactured by DIC)

((Meth) acrylic acid)
Acrylic acid Methacrylic acid

(Photo radical curing agent)
Photo radical curing agent ("Irgacure 651" manufactured by BASF Japan)

(Curing agent)
Curing agent 1 ("HXA-392HP" manufactured by Asahi Kasei E-Materials)
Hardener 2 (Nippon Soda Co., Ltd. “TEP-2E4MZ”)

(flux)
Glutaric acid (Wako Pure Chemical Industries)
Adipic acid (Wako Pure Chemical Industries, Ltd.)

(Conductive particles)
Conductive particles A: Conductive particles A (average particle diameter 15 μm) having a metal layer in which a nickel plating layer is formed on the surface of divinylbenzene resin particles and a gold plating layer is formed on the surface of the nickel plating layer )
Conductive particle B: conductive particle B in which a copper layer is formed on the surface of divinylbenzene resin particles, and a solder layer is formed on the surface of the copper layer

[Method for Producing Conductive Particle B]
Divinylbenzene resin particles having an average particle diameter of 10 μm (“Micropearl SP-210” manufactured by Sekisui Chemical Co., Ltd.) were subjected to electroless nickel plating to form a base nickel plating layer having a thickness of 0.1 μm on the surface of the resin particles. Next, the resin particles on which the base nickel plating layer was formed were subjected to electrolytic copper plating to form a 1 μm thick copper layer. Furthermore, electrolytic plating was performed using an electrolytic plating solution containing tin and bismuth to form a solder layer having a thickness of 1 μm. Thus, a 1 μm thick copper layer is formed on the surface of the resin particles, and a 1 μm thick solder layer (tin: bismuth = 43 wt%: 57 wt%) is formed on the surface of the copper layer. Conductive particles B were prepared.

  Conductive particles C: SnBi solder particles (“DS-10” manufactured by Mitsui Kinzoku Co., Ltd., average particle diameter (median diameter) 12 μm)

(Other ingredients)
Adhesive agent (Shin-Etsu Chemical Co., Ltd. “KBE-403”)

(Examples 1 to 14 and Comparative Examples 1 and 2)
The components shown in Table 1 below were blended in the blending amounts shown in Table 1 below to obtain anisotropic conductive paste.

(Production of connection structure)
A glass epoxy substrate (FR-4 substrate) having a copper electrode pattern (copper electrode thickness 10 μm) with L / S of 100 μm / 100 μm on the upper surface was prepared. Moreover, the flexible printed circuit board which has a copper electrode pattern (copper electrode thickness 10 micrometers) with L / S of 100 micrometers / 100 micrometers on the lower surface was prepared.

  The obtained anisotropic conductive paste was applied on the upper surface of the glass epoxy substrate so as to have a thickness of 200 μm to form an anisotropic conductive paste layer. Next, UV irradiation was performed for 10 seconds under the condition of 200 mW at a wavelength of 365 nm with an LED-UV irradiator, and the anisotropic conductive paste was made into a B-stage. Next, the flexible printed circuit board was laminated on the upper surface of the anisotropic conductive paste layer which was B-staged and cured so that the electrodes face each other. Then, while adjusting the temperature of the head so that the temperature of the anisotropic conductive paste layer is 185 ° C., a pressure heating head is placed on the upper surface of the flexible printed circuit board, and a pressure of 2.0 MPa is applied. The conductive paste layer was fully cured at 185 ° C. to obtain a connection structure.

(Evaluation)
(1) Acid value The acid value was determined according to ISO 6618-1997.

  1 g of the obtained anisotropic conductive paste and 30 g of pure water were stirred and mixed at 2000 rpm for 3 minutes using a planetary stirrer. The supernatant was titrated with an indicator phenolphthalein using a 0.05N aqueous KOH solution to determine the acid value.

(2) Storage stability Using an E-type viscosity measuring device (“VISCOMETER TV-22” manufactured by TOKI SANGYO CO. LTD, rotor used: φ15 mm, temperature: 25 ° C.), the viscosity η1 (rotation) of the anisotropic conductive paste Several 5 rpm) was measured. Similarly, the viscosity η2 of the anisotropic conductive paste after standing at 25 ° C. for 3 days was measured in the same manner as the viscosity η1. Storage stability was determined according to the following criteria.

[Criteria for storage stability]
○○: η2 / η1 is less than 1.3 ○: η2 / η1 is 1.3 or more and less than 1.5 ×: η2 / η1 is 1.5 or more

(3) Continuity test The connection resistance between the upper and lower electrodes of the obtained connection structure was measured by a four-terminal method. The average value of the two connection resistances was calculated. Note that the connection resistance can be obtained by measuring the voltage when a constant current is passed from the relationship of voltage = current × resistance. The continuity test between the upper and lower electrodes was judged according to the following criteria.

[Criteria for continuity test]
○○: Average value of connection resistance is 8.0Ω or less ○: Average value of connection resistance exceeds 8.0Ω and 10.0Ω or less △: Average value of connection resistance exceeds 10.0Ω and 15.0Ω or less × : Average connection resistance exceeds 15.0Ω

(4) Continuity test after moisture resistance test The obtained connection structure was allowed to stand for 1000 hours in an atmosphere at 85 ° C. and a humidity of 85%, and then the continuity test was evaluated in the same manner as in the above (3) evaluation of the continuity test. . The continuity test after the moisture resistance test was determined according to the following criteria.

[Criteria for continuity test after moisture resistance test]
○○: Average value of connection resistance is 8.0Ω or less ○: Average value of connection resistance exceeds 8.0Ω and 10.0Ω or less △: Average value of connection resistance exceeds 10.0Ω and 15.0Ω or less × : Average connection resistance exceeds 15.0Ω

(5) Adhesive strength In the obtained connection structure, 90 ° peel adhesive strength was measured with an automatic tensile tester in an atmosphere of a tensile speed of 10 (mm / min) and 23 ° C.

[Adhesion criteria]
◯: Adhesive force is 15 N / cm or more ○: Adhesive force is 10 N / cm or more and less than 15 N / cm Δ: Adhesive force is 5 N / cm or more and less than 10 N / cm X: Adhesive force is less than 5 N / cm

(6) Adhesive strength after moisture resistance test The obtained connection structure was allowed to stand for 1000 hours in an atmosphere at 85 ° C and humidity of 85%, and then the adhesive strength was evaluated in the same manner as in the evaluation of (5) adhesive strength. . The adhesive strength after the moisture resistance test was determined according to the following criteria.

[Judgment criteria for adhesive strength after moisture resistance test]
◯: Adhesive force is 15 N / cm or more ○: Adhesive force is 10 N / cm or more and less than 15 N / cm Δ: Adhesive force is 5 N / cm or more and less than 10 N / cm X: Adhesive force is less than 5 N / cm

  The composition and results are shown in Table 1 below.

  The evaluation results of the (3) continuity test of Examples 4, 13, and 14 were all “◯◯”, but the connection resistance of Example 4 was lower than that of Examples 13 and 14. In addition, the evaluation results of the continuity test after the (4) moisture resistance test of Examples 4, 13, and 14 are all “◯◯”, but the Example 4 is more after the moisture resistance test than the Examples 13 and 14. The connection resistance of was low. Further, the evaluation results of (5) adhesive strength of Examples 4, 13, and 14 were all “◯◯”, but the adhesive strength of Example 4 was higher than that of Examples 13 and 14. Furthermore, the evaluation results of the adhesive strength after (6) moisture resistance test of Examples 4, 13, and 14 are all “◯◯”, but Example 4 is more after the moisture resistance test than Examples 13 and 14. The adhesive strength of was high.

DESCRIPTION OF SYMBOLS 1 ... Conductive particle 1a ... Surface 2 ... Resin particle 2a ... Surface 3 ... Conductive layer 4 ... 1st conductive layer 4a ... Surface 5 ... Solder layer 5a ... Molten solder layer part 11 ... Conductive particle 12 ... Solder layer 16 ... Solder particles 21 ... Connection structure 22 ... First connection object member 22a ... Surface 22b ... First electrode 23 ... Second connection object member 23a ... Surface 23b ... Second electrode 24 ... Connection part

Claims (6)

Including at least conductive particles whose outer surface is electrically conductive, a curable compound, a curing agent, and (meth) acrylic acid,
The electrically conductive material whose content of the said (meth) acrylic acid in electrically conductive material 100weight% is 0.0001 weight% or more and 0.1 weight% or less.   The conductive material according to claim 1, wherein a content of the (meth) acrylic acid in 100% by weight of the conductive material is 0.05% by weight or less.   The conductive material according to claim 1 or 2, wherein a content of the (meth) acrylic acid in 100% by weight of the conductive material is 0.005% by weight or more.   The electrically conductive material of any one of Claims 1-3 containing an epoxy (meth) acrylate as the said sclerosing | hardenable compound.   The conductive material according to any one of claims 1 to 4, which is a circuit connection material used for electrical connection between electrodes. 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 connection portion is formed of the conductive material according to any one of claims 1 to 5,
A connection structure in which the first electrode and the second electrode are electrically connected by the conductive particles.

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