JP2013033735A - Anisotropic conductive material and connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anisotropic conductive material having a high flux effect and capable of enhancing conduction reliability when used for an electrical connection between electrodes.SOLUTION: The anisotropic conductive material includes: a binder resin; a conductive particle 1 whose external surface at least is a solder 5; and a component which is capable of removing an oxide film of an outer surface of the solder 5. The component is a component which discharges an inorganic oxide ion by heating or discharges an organic acid ion containing a boron atom by heating.

Description

  The present invention relates to an anisotropic conductive material including conductive particles having solder, and for example, electrically connects 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 an anisotropic conductive material that can be used for the purpose, and a connection structure using the anisotropic 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.

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

  As an example of the anisotropic conductive material, the following Patent Document 1 discloses an anisotropic conductive paste containing an insulating resin and a solder particle component. This anisotropic conductive paste may contain oxide film breaking particles. Here, as the solder particle component, a particle is described in which any one kind of particles selected from the group consisting of solder, resin, ceramic and metal is used as a core and the surface thereof is coated with the solder component. However, in the Example of patent document 1, there is no description about the particle | grains which made resin the nucleus and coat | covered the surface with the solder component as a solder particle component.

  The following Patent Document 2 discloses an anisotropic conductive paste containing an epoxy adhesive having a flux action and SnBi solder powder. In Patent Document 2, an epoxy adhesive containing an epoxy resin, a curing agent, and an organic acid is cited as an epoxy adhesive having a flux action. Examples of the organic acid include dibasic acids having an alkyl group in the side chain.

JP 2006-108523 A JP 2006-199937 A

  When the above connection structure is obtained using conventional anisotropic conductive materials as described in Patent Documents 1 and 2, the connection structure is formed by forming an oxide film on the surface of the metal electrode. The conduction reliability in the body may be lowered. In general, an oxide film is formed on the surface of the solder particles. Even when an oxide film is formed on the surface of the solder particles, the conduction reliability in the connection structure may be lowered.

  Conventionally, flux is sometimes used to remove the oxide film on the surface of the metal electrode and the oxide film on the surface of the solder particles. As the flux, rosin is generally used.

  However, when rosin is used, the rosin may react with the binder resin due to the carboxyl group in the rosin. For this reason, there is a problem that a sufficient flux effect cannot be obtained. Furthermore, there is a problem that the storage stability is lowered due to an increase in the viscosity of the anisotropic conductive material using rosin.

  An object of the present invention is to provide an anisotropic conductive material that has a high flux effect and can improve conduction reliability when used for electrical connection between electrodes, and a connection using the anisotropic conductive material. It is to provide a structure.

  An object of the present invention is to provide an anisotropic conductive material capable of enhancing the thermal shock resistance of a connection structure when the connection structure is obtained by electrically connecting the electrodes, and the anisotropic It is to provide a connection structure using a conductive material.

  Furthermore, the limited objective of this invention is to provide the anisotropic conductive material which can improve storage stability, and the connection structure using this anisotropic conductive material.

  According to a wide aspect of the present invention, a binder resin, conductive particles having at least an outer surface of solder, and a component capable of removing an oxide film on the outer surface of the solder, the component is inorganic by heating. An anisotropic conductive material is provided that is a component that releases acid ions or organic acid ions containing boron atoms by heating.

  In a specific aspect of the anisotropic conductive material according to the present invention, the component releases inorganic acid ions containing phosphorus atoms by heating, releases inorganic acid ions containing antimony atoms by heating, or heating. Is a component that releases organic acid ions containing boron atoms.

  In another specific aspect of the anisotropic conductive material according to the present invention, the binder resin includes a thermoplastic compound or a thermosetting compound.

  In still another specific aspect of the anisotropic conductive material according to the present invention, the binder resin includes an epoxy compound.

  In another specific aspect of the anisotropic conductive material according to the present invention, the component is a thermal cation generator.

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

  In another specific aspect of the anisotropic conductive material according to the present invention, 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 a solder layer.

  In still another specific aspect of the anisotropic conductive material according to the present invention, a flux different from the above components is further included.

  In another specific aspect of the anisotropic conductive material according to the present invention, a tertiary amine compound is further included.

  The anisotropic conductive material according to the present invention is preferably an anisotropic conductive material used for connecting a connection target member having a copper electrode.

  A connection structure according to the present invention includes a first connection target member, a second connection target member, and a connection part that electrically connects the first and second connection target members, The connecting portion is formed of the above-described anisotropic conductive material.

  In a specific aspect of the connection structure according to the present invention, the first connection target member has a first electrode on the upper surface, and the second connection target member has a second electrode on the lower surface, The first electrode and the second electrode are electrically connected by the conductive particles.

  In the connection structure according to the present invention, it is preferable that at least one of the first electrode and the second electrode is a copper electrode.

  The anisotropic conductive material according to the present invention includes a binder resin, conductive particles having at least an outer surface of solder, and a component capable of removing an oxide film on the outer surface of the solder, and the component further includes: Since it is a component that releases inorganic acid ions by heating or releases organic acid ions containing boron atoms by heating, the flux effect is high. Further, when the anisotropic conductive material according to the present invention is used for electrical connection between electrodes, conduction reliability can be improved.

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

  Details of the present invention will be described below.

  The anisotropic conductive material according to the present invention includes a binder resin, conductive particles having at least an outer surface of solder, and a component capable of removing an oxide film on the outer surface of the solder (hereinafter referred to as component X). Is included). In conductive particles having at least an outer surface of solder, an oxide film is generally formed on the surface of the solder, and an oxide film may be formed on the surface of the solder during storage. In the anisotropic conductive material according to the present invention, the component X can remove the oxide film formed on the outer surface of the solder or when the oxide film is formed on the outer surface of the solder. The oxide film can be removed.

  In the anisotropic conductive material according to the present invention, the component X is a component that releases inorganic acid ions by heating or releases organic acid ions containing boron atoms by heating.

  By adopting the above composition in the anisotropic conductive material according to the present invention, the flux effect is considerably enhanced, particularly by using the specific component X. As a result, when the electrodes are electrically connected using the anisotropic conductive material according to the present invention, the conduction reliability can be effectively increased. In particular, when a connection target member having a copper electrode is connected, the conduction reliability can be effectively increased. The present inventors have found that the specific component X greatly contributes to significantly increasing the flux effect and has an action of effectively removing the oxide film on the solder surface and the oxide film on the electrode surface. In the anisotropic conductive material according to the present invention, the reliability of conduction between the electrodes in the connection structure can be improved without using a flux such as rosin or without using a flux different from the component X.

  Furthermore, by adopting the above composition in the anisotropic conductive material according to the present invention, the high conduction reliability of the connection structure can be sufficiently maintained even when a thermal shock such as a thermal cycle is applied, and the thermal shock characteristics in the connection structure Can be increased. In addition, the use of the above component X instead of rosin or the like increases the storage stability of the anisotropic conductive material, and the anisotropic conductive material changes in viscosity even if the anisotropic conductive material is stored for a long period of time. Is less likely to occur. For this reason, an anisotropic conductive material can be arrange | positioned stably and the stable and uniform connection structure can be obtained.

  The anisotropic conductive material according to the present invention is preferably an anisotropic conductive material that can be cured by heating. In this case, inorganic acid ions or organic acid ions containing boron atoms can be efficiently released from the component X by heat generated when the anisotropic conductive material is cured by heating. The anisotropic conductive material according to the present invention may be an anisotropic conductive material that can be cured by both light irradiation and heating. In this case, the anisotropic conductive material is semi-cured (B-staged) by light irradiation, and after the fluidity of the anisotropic conductive material is reduced, the anisotropic conductive material is cured by heating. it can.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

[Conductive particles]
The conductive particles are not particularly limited as long as at least the outer surface is solder. The solder in the conductive particles is a solder part and is preferably a solder layer. The conductive particles preferably include base particles and a conductive layer disposed on the surface of the base particles, and at least the outer surface of the conductive layer is a solder layer. 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 resin particles formed of a resin. 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. A layer is preferred.

  In FIG. 1, the electroconductive particle contained in the anisotropic conductive material which concerns on one Embodiment of this invention is 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 2 a of the resin particle 2 and a solder layer 5 (solder, second conductive layer disposed on the surface 4 a of the first conductive layer 4. ). The outer surface layer of the conductive layer 3 is a solder layer 5. Therefore, the conductive particle 1 has the solder layer 5 as a part of the conductive layer 3, and is further separated between the resin particle 2 and the solder layer 5 as a part of the conductive layer 3 in addition to the solder layer 5. The conductive layer 4 is provided. 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 surface layer on the outer side of the conductive layer in the conductive particles may be 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. Solder particles may also be used. In addition, the said solder particle does not have a base particle in a core, and is not a core-shell particle. As for the said solder particle, both a center part and an outer surface are formed with the solder. From the viewpoint of controlling the interval between the electrodes with high accuracy, the conductive particles are preferably not the solder particles.

  Examples of the resin for forming the resin particles include polyolefin resin, acrylic resin, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polyethylene terephthalate, polysulfone, and polyphenylene. Examples thereof include oxides, polyacetals, polyimides, polyamideimides, polyetheretherketones, and polyethersulfones. Since the 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.

  The method for forming a conductive layer on the surface of the resin particles and the method for forming a solder layer on the surface of the resin particles 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, In addition, a method of coating the surface of the resin particles with metal powder or a paste containing metal powder and a binder may be used. 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 first conductive layer is preferably a method by physical collision. The solder layer is preferably disposed on the surface of the first conductive layer by physical impact.

  The material constituting the solder (solder layer or the like) is preferably a filler material having a liquidus line of 450 ° C. or lower 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.

  Conventionally, the particle diameter of conductive particles having a solder layer on the outer surface layer of the conductive layer has been about several hundred μm. This is because the solder layer could not be formed uniformly even if conductive particles having a particle size of several tens of μm and the surface layer being a solder layer were obtained. On the other hand, when the solder layer is formed by optimizing the dispersion conditions during electroless plating, the conductive particles have a particle size of several tens of μm, in particular, a conductive 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, the tin content 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 is appropriately determined in consideration of the melting point of the solder and the like. The content of tin in 100% by weight of solder 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 of the first conductive layer is preferably 5 nm or more, more preferably 10 nm or more, still more preferably 25 nm or more, 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 of the first conductive layer is not less than the above lower limit, the conductivity is sufficiently high. When the thickness of the outermost layer of the first conductive layer is not more than the above upper limit, the difference in coefficient of thermal expansion between the base particles and the outermost layer of the first conductive layer becomes small, 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. In addition, the size is suitable for the conductive particles in the anisotropic conductive material, the distance between the electrodes connected via the conductive particles is not too large, and the conductive layer is difficult to peel off from the surface of the base particle. Become.

  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 2.0 or less. Further, when the first conductive layer is present between the resin particles and the solder layer, the ratio of the average particle size B of the resin particles to the average particle size B of the conductive particle portion excluding the solder layer (B / A) is greater than 1.0, preferably 1.5 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.

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

  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 anisotropic conductive material disposed between the electrodes and the connection portion 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.

Anisotropic conductive materials for flip chip applications:
The anisotropic 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 10 μm or less, a short circuit is more unlikely to occur between adjacent electrodes.

Anisotropic conductive material for COF:
The anisotropic conductive material which concerns on this invention is used suitably for the connection (COF (Chip on Film)) of a semiconductor chip and a flexible printed circuit board.

  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 resin particles and the conductive particles indicates a number average particle diameter. The average particle diameter of the resin particles and the conductive particles is determined 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 anisotropic conductive material, the content of the conductive particles is preferably 1% by weight or more, more preferably 2% by weight or more, preferably 50% by weight or less, and more preferably 45% by weight or less. . A conductive particle can be easily arrange | positioned between the upper and lower electrodes which should be connected as content of the said electroconductive particle is more than the said minimum and below the said upper limit. Furthermore, it becomes difficult to electrically connect adjacent electrodes that should not be connected via a plurality of conductive particles. That is, a short circuit between adjacent electrodes can be further prevented.

[Component X]
The anisotropic conductive material includes a component X that can remove the oxide film on the outer surface of the solder. The component X is a component that releases inorganic acid ions by heating or releases organic acid ions containing boron atoms by heating. The component X is preferably a component that releases inorganic acid ions by heating, and is preferably a component that releases organic acid ions containing boron atoms by heating. From the viewpoint of more effectively expressing the addition effect of the component X and further improving the conduction reliability in the connection structure, the component releases inorganic acid ions containing phosphorus atoms by heating, or by heating. A component that releases inorganic acid ions containing antimony atoms or releases organic acid ions containing boron atoms by heating is preferable.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

The anisotropic conductive material according to the present invention preferably contains a thermal cation generator. The component X is preferably a thermal cation generator. The component X is preferably a sulfonium-based thermal cation generator. The component having the sulfonium cation moiety and the anion moiety of SbF ⁶⁻ , the anion moiety of PF ⁶⁻ , or the anion moiety represented by the above formula (2) acts as a thermal cation generator.

  The content of the component X is not particularly limited. The content of the component X is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, further preferably 5 parts by weight or more with respect to 100 parts by weight of the curable compound curable by heating. The amount is particularly preferably 10 parts by weight or more, preferably 40 parts by weight or less, more preferably 30 parts by weight or less, and still more preferably 20 parts by weight or less. When the content of the component X is not less than the above lower limit and not more than the above upper limit, the oxide film on the solder surface and the oxide film on the electrode surface can be more effectively removed, and the conduction reliability in the connection structure is further enhanced. Become.

  The content of the thermal cation generator is not particularly limited. The content of the thermal cation generator is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, and still more preferably 0.00 parts by weight with respect to 100 parts by weight of the curable compound curable by heating. 1 part by weight or more, particularly preferably 0.2 part by weight or more, preferably 20 parts by weight or less, more preferably 15 parts by weight or less, and further preferably 10 parts by weight or less. When the content of the thermal cation generator is not less than the above lower limit and not more than the above upper limit, the anisotropic conductive material is sufficiently thermoset, and the conduction reliability in the connection structure is further enhanced.

  Further, the blending ratio of the conductive particles to the component X or the thermal cation generator in the anisotropic conductive material is preferably 0.5: 1 to 30: 1 by weight, and 0.75. : 1 to 25: 1 is more preferable, and 1: 1 to 20: 1 is still more preferable.

(Other ingredients)
The anisotropic conductive material preferably contains a thermosetting agent. More preferably, the component X is a thermal cation generator, and the anisotropic conductive material further contains a thermosetting agent. By the combined use of the thermal cation generator and the thermosetting agent, the conduction reliability and the thermal shock resistance in the connection structure are further improved. The thermosetting agent is different from the component X. The thermosetting agent is preferably different from the thermal cation generator.

  Since the anisotropic conductive material can be cured more rapidly at a low temperature, the thermosetting agent is preferably an imidazole curing agent, a polythiol curing agent, or an amine curing agent. Moreover, since the storage stability of an anisotropic conductive material becomes high, a latent hardening | curing agent is preferable. The latent curing agent is preferably a latent imidazole curing agent, a latent polythiol curing agent or a latent amine curing agent. The thermosetting agent may be coated with a polymer material such as polyurethane resin or polyester resin.

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

  The polythiol curing agent is not particularly limited, and examples 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.

  The content of the thermosetting agent is not particularly limited. The content of the thermosetting agent is preferably 5 parts by weight or more, more preferably 10 parts by weight or more, preferably 40 parts by weight or less, more preferably 100 parts by weight of the curable compound curable by heating. 30 parts by weight or less, more preferably 20 parts by weight or less. When the content of the thermosetting agent is not less than the above lower limit and not more than the above upper limit, the anisotropic conductive material is sufficiently thermoset, and the connection reliability and thermal shock resistance of the connection structure are further improved.

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

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

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

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

  The anisotropic conductive material according to the present invention preferably contains a flux different from the component X. Use of the flux makes it difficult to form an oxide film on the surface of the solder, and the oxide film formed on the solder or electrode surface can be effectively removed. As a result, the conduction reliability in the connection structure is further increased. Note that the anisotropic conductive material does not necessarily contain a flux.

  The flux is not particularly limited. As the flux, 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 hydrazine. Examples of the pine resin include activated pine resin and non-activated pine resin. The flux is preferably rosin. By using pine resin, the connection resistance between the electrodes can be lowered.

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

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

  In 100% by weight of the anisotropic conductive material, the content of the flux different from the component X is preferably 0.5% by weight or more, preferably 30% by weight or less, more preferably 25% by weight or less. When the flux content is not less than the above lower limit and not more than the above upper limit, an oxide film is hardly formed on the surface of the solder, and the oxide film formed on the solder or the 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.

  The anisotropic conductive material according to the present invention preferably further contains a tertiary amine compound. By using the tertiary amine compound, the storage stability of the anisotropic conductive material is further increased, and the storage stability of the component X in the anisotropic conductive material is further increased. For this reason, the addition effect of the said component X expresses more effectively, and the conduction | electrical_connection reliability in a connection structure becomes still higher. Note that the anisotropic conductive material does not necessarily include a tertiary amine compound.

  The content of the tertiary amine compound is not particularly limited in 100% by weight of the anisotropic conductive material. The content of the tertiary amine compound is preferably 0.005% by weight or more, preferably 1% by weight or less. When the content of the tertiary amine compound is not less than the above lower limit and not more than the above upper limit, the storage stability of the component X in the anisotropic conductive material is further increased, and an oxide film is further formed on the surface of the solder. It becomes difficult to form, and the oxide film formed on the solder or the electrode surface can be further effectively removed.

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

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

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

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

  The viscosity of the anisotropic conductive paste at 25 ° C. is preferably 3 Pa · s or more, more preferably 5 Pa · s or more, preferably 500 Pa · s or less, more preferably 300 Pa · s or less. When the viscosity is equal to or higher than the lower limit, sedimentation of conductive particles in the anisotropic 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 anisotropic conductive paste before coating is within the above range, after applying the anisotropic conductive paste on the first connection target member, the flow of the anisotropic conductive paste before curing is further increased. Further suppression is possible, and voids are further less likely to occur.

  The anisotropic conductive material according to the present invention is preferably an anisotropic conductive material used for connecting a connection target member having a copper electrode. An oxide film is easily formed on the surface of the copper electrode. On the other hand, by using the anisotropic conductive material according to the present invention, the oxide film on the surface of the copper electrode can be effectively removed, and the conduction reliability in the connection structure can be improved.

  The anisotropic conductive material which concerns on this invention can be used in order to adhere | attach various connection object members. The anisotropic conductive material is suitably used for obtaining a connection structure in which the first and second connection target members are electrically connected.

  FIG. 3 is a cross-sectional view schematically showing an example of a connection structure using an anisotropic conductive material according to an embodiment of the present invention.

  A connection structure 21 shown in FIG. 3 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 connection part 24 is formed of an anisotropic conductive material including the conductive particles 1. In FIG. 3, 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 upper surface 22a (front surface). The second connection target member 23 has a plurality of second electrodes 23b on the lower surface 23a (front 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 anisotropic conductive material is disposed between the first connection object member and the second connection object member to obtain a laminate, and then the lamination Examples include a method of heating and pressurizing the body. The solder 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 said pressurization is about 9.8 * 10 < ⁴ > -4.9 * 10 < ⁶ > Pa. The temperature of the said heating is about 120-220 degreeC.

  FIG. 4 is an enlarged front sectional view of a connection portion between the conductive particle 1 and the first and second electrodes 22b and 23b in the connection structure 21 shown in FIG. As shown in FIG. 4, in the connection structure 21, by heating and pressurizing the laminate, the solder layer 5 of the conductive particles 1 is melted, and then the melted solder layer portion 5 a has the first and second solder layers. 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 can be increased. For this reason, the conduction | electrical_connection reliability of the connection structure 21 can be improved. In general, the flux is gradually deactivated by heating. In FIG. 4, the first conductive layer 4 is not in contact with the first and second electrodes 22b and 23b. The first conductive layer 4 is preferably in contact with the first electrode 22b, and is preferably in contact with the second electrode 23b.

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

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

  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 anisotropic 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, Comparative Examples, and Reference Examples. The present invention is not limited only to the following examples.

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

(Binder resin)
Thermoplastic compound 1 (phenoxy resin, “YP-50 (40 wt% MEK (methyl ethyl ketone) solution)” manufactured by Nippon Steel Chemical Co., Ltd.)
Thermoplastic compound 2 (urethane resin, “NIPPOLAN 3110 (35 wt% ethyl acetate solution)” manufactured by Nippon Polyurethane Industry Co., Ltd .: “NIPPOLAN 3022 (25 wt% MEK (methyl ethyl ketone) solution)” = 1: 1 (weight ratio))
Thermosetting compound (epoxy resin (epoxy compound), “EXA-4850-150” manufactured by DIC)
Thermosetting agent (imidazole compound, “2P-4MZ” manufactured by Shikoku Kasei Co., Ltd.)

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

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

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

(Other ingredients)
Flux (rosin): Main component Abietic acid Tertiary amine compound (N, N-dimethylbenzylamine)
Conductive particles 1 (solder particles, entirely formed of solder, tin: bismuth = 43 wt%: 57 wt%, average particle diameter 20 μm)
Conductive particles 2 (resin core solder coated particles, prepared by the following procedure)

  Electroless nickel plating was performed on divinylbenzene resin particles having an average particle diameter of 20 μm (manufactured by Sekisui Chemical Co., Ltd., Micropearl SP-220) 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 (resin core solder coated particles) were prepared.

(Examples 1 to 14, Comparative Examples 1 to 3 and Reference Examples 1 and 2)
The components shown in Tables 1 and 2 below were blended in the blending amounts shown in Tables 1 and 2 to obtain anisotropic conductive pastes.

(Evaluation)
(1) Storage stability Using a viscometer (“TV-22” manufactured by Toki Sangyo Co., Ltd.), the viscosity η1 of the anisotropic conductive material immediately after production was measured under the conditions of 25 ° C. and 5 rpm. After producing the anisotropic conductive material, it was stored at 25 ° C. for 72 hours. Under the same conditions as the viscosity η1, the viscosity η2 of the anisotropic conductive material after storage was measured. Storage stability was determined according to the following criteria.

[Criteria for storage stability]
◯: Viscosity η2 is 120% or less of viscosity η1 ○: Viscosity η2 exceeds 120% of viscosity η1, 140% or less ×: Viscosity η2 exceeds 140% of viscosity η1

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

  An anisotropic conductive material layer was formed on the upper surface of the glass epoxy substrate by coating the anisotropic conductive material immediately after fabrication so as to have a thickness of 50 μm. At this time, the anisotropic conductive paste containing the solvent was solvent-dried. Next, the flexible printed circuit board was laminated on the upper surface of the anisotropic conductive material layer so that the electrodes face each other. Then, while adjusting the temperature of the head so that the temperature of the anisotropic conductive material layer is 185 ° C., a pressure heating head is placed on the upper surface of the semiconductor chip and a pressure of 2.0 MPa is applied to melt the solder. And the anisotropic conductive material layer was hardened at 185 degreeC, and the connection structure A was obtained. Further, a connection structure B was obtained in the same manner as the connection structure A except that the anisotropic conductive material layer was cured at 200 ° C. When the conductive particles 2 were used, in the obtained connection structures A and B, the copper layer in the conductive particles 2 was in contact with the upper and lower electrodes.

(3) Conductivity test between upper and lower electrodes The connection resistance between the upper and lower electrodes of the connection structures A and B obtained in the preparation of the above (2) 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 was judged according to the following criteria.

[Criteria for continuity test]
○○: The average value of connection resistance is 8.0Ω or less ○: The average value of connection resistance is more than 8.0 and less than 10.0Ω ×: The average value of connection resistance is more than 10.0Ω

(4) Thermal shock resistance test 20 pieces of each of the obtained connection structures A and B were prepared, held at −30 ° C. for 30 minutes, then heated to 80 ° C. and held for 30 minutes, and then −30 ° C. A cold cycle test was performed in which the process of lowering the temperature to 1 cycle was performed. Ten connection structures were taken out after 500 cycles and 1000 cycles, respectively.

  It was evaluated whether 10 connection structures after 500 cycles of the thermal cycle test and 10 connection structures after 1000 cycles of the thermal cycle test had poor conduction between the upper and lower electrodes. The thermal shock resistance test was judged according to the following criteria.

[Criteria for thermal shock resistance test]
◯: In all 10 connection structures, the rate of increase in connection resistance from the connection resistance before the thermal cycle test is 5% or less. ○: Connection resistance before the thermal cycle test in all 10 connection structures. The connection resistance rise rate from 5 to exceeds 10% and 10% or less ×: Of 10 connection structures, the connection structure from which the connection resistance increase rate before the thermal cycle test exceeds 10% Have more than one body

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 21 ... Connection structure 22 ... First connection target member 22a ... Upper surface 22b ... First electrode 23 ... Second connection target member 23a ... Lower surface 23b ... Second electrode 24 ... Connection portion

Claims (13)

A binder resin,
Conductive particles having at least an outer surface made of solder;
A component capable of removing the oxide film on the outer surface of the solder,
An anisotropic conductive material, wherein the component is a component that releases inorganic acid ions by heating or releases organic acid ions containing boron atoms by heating.   The component is a component that releases inorganic acid ions containing phosphorus atoms by heating, releases inorganic acid ions containing antimony atoms by heating, or releases organic acid ions containing boron atoms by heating. Item 10. An anisotropic conductive material according to Item 1.   The anisotropic conductive material according to claim 1 or 2, wherein the binder resin contains a thermoplastic compound or a thermosetting compound.   The anisotropic conductive material of any one of Claims 1-3 in which the said binder resin contains an epoxy compound.   The anisotropic conductive material of any one of Claims 1-4 whose said component is a thermal cation generator.   The anisotropic conductive material according to claim 1, further comprising a thermosetting agent.   The conductive particles according to any one of claims 1 to 6, wherein the conductive particles include resin particles and a conductive layer disposed on a surface of the resin particles, and at least an outer surface of the conductive layer is a solder layer. The anisotropic conductive material as described.   The anisotropic conductive material according to claim 1, further comprising a flux different from the component.   The anisotropic conductive material according to any one of claims 1 to 8, further comprising a tertiary amine compound.   The anisotropic conductive material of any one of Claims 1-9 which is an anisotropic conductive material used in order to connect the connection object member which has a copper electrode. A first connection target member, a second connection target member, and a connection part that electrically connects the first and second connection target members;
The connection structure in which the said connection part is formed with the anisotropic conductive material of any one of Claims 1-10. The first connection object member has a first electrode on an upper surface;
The second connection target member has a second electrode on the lower surface;
The connection structure according to claim 11, wherein the first electrode and the second electrode are electrically connected by the conductive particles.   The connection structure according to claim 12, wherein at least one of the first electrode and the second electrode is a copper electrode.

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