JP2013118180A - Anisotropic conductive material and connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anisotropic conductive material which sufficiently ensures the insulation quality even when electrodes are electrically connected to obtain a connection structure and the obtained connection structure is subject to high temperature and high humidity.SOLUTION: An anisotropic conductive material according to this invention includes: a binder resin; first conductive particles whose at least outer surfaces are formed by solder; and second particles. An average particle size of the second particle is smaller than an average particle size of the first conductive particle. Out of 100%, i.e., all of the first conductive particles, the number of the first conductive particles which have the particle size smaller than the average particle size of the second particle is 20% or lower.

Description

  The present invention relates to an anisotropic conductive material including conductive particles having at least an outer surface made of 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 connection. The present invention also relates to 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.

  Patent Document 2 below discloses an anisotropic conductive material including an adhesive composition that flows by heating, first particles, and second particles. The first particle has a core mainly composed of a low melting point metal having a melting point of 130 to 250 ° C., and a resin composition that covers the surface of the core and has a softening point lower than the melting point of the low melting point metal. And an insulating layer formed by. The second particle is mainly composed of a material having an average particle size smaller than that of the core of the first particle and having a melting point or a softening point higher than the melting point of the low melting point metal.

JP 2006-108523 A JP 2009-277852 A

  When the above connection structure is obtained by using the conventional anisotropic conductive material as described in Patent Documents 1 and 2, when the obtained connection structure is exposed to high temperature and high humidity, the insulating structure May decrease. Therefore, when the conventional anisotropic conductive material is used, there exists a problem that the insulation reliability of a connection structure becomes low.

  The object of the present invention is to provide an anisotropic structure that can sufficiently secure insulation even when the obtained connection structure is exposed to high temperature and high humidity when the connection structure is obtained by electrically connecting the electrodes. It is to provide a conductive structure and a connection structure using the anisotropic conductive material.

  According to a wide aspect of the present invention, the binder resin, the first conductive particles at least whose outer surface is solder, and the second particles are contained, and the average particle diameter of the second particles is Of the first conductive particles smaller than the average particle size of the first conductive particles and smaller than the average particle size of the second particles in 100% of the total number of the first conductive particles. An anisotropic conductive material having a number ratio of 20% or less is provided.

  In a specific aspect of the anisotropic conductive material according to the present invention, the average particle size of the second particles is ¼ or more and 9/10 or less of the average particle size of the first conductive particles. .

  In another specific aspect of the anisotropic conductive material according to the present invention, the first conductive particles are solder particles, or resin particles and a conductive layer disposed on the surface of the resin particles. And conductive particles in which at least the outer surface of the conductive layer is a solder layer. The first conductive particles are preferably conductive particles having resin particles and a conductive layer disposed on the surface of the resin particles, at least the outer surface of the conductive layer being a solder layer.

  In another specific aspect of the anisotropic conductive material according to the present invention, the average particle size of the second particles is one or more times the average particle size of the resin particles in the first conductive particles. 8 times or less.

  In another specific aspect of the anisotropic conductive material according to the present invention, the second particle is an insulating particle or a conductive particle at least whose outer surface is solder.

  In another specific aspect of the anisotropic conductive material according to the present invention, the second particles are solder particles.

  The binder resin preferably contains a thermoplastic compound or contains a curable compound that can be cured by heating and a thermosetting agent. The thermosetting agent preferably contains a thermal cation generator.

  The connection structure according to the present invention includes a first connection object member having a first electrode on the surface, a second connection object member having a second electrode on the surface, and the first and second connection objects. A connecting portion connecting members, the connecting portion being formed of the above-described anisotropic conductive material, and the first electrode and the second electrode being the first conductive particles. Are electrically connected.

  The anisotropic conductive material according to the present invention contains a binder resin, at least first conductive particles whose outer surface is solder, and second particles, and the average particle diameter of the second particles is as follows. The first conductivity is smaller than the average particle size of the first conductive particles and smaller than the average particle size of the second particles in 100% of the total number of the first conductive particles. Since the ratio of the number of particles is 20% or less, when the connection structure is obtained by electrically connecting the electrodes using the anisotropic conductive material according to the present invention, the obtained connection structure is Even when exposed to high temperature and high humidity, sufficient insulation can be secured.

FIG. 1 is a cross-sectional view schematically showing conductive particles that can be used 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 cross-sectional view showing another modification of the conductive particles. FIG. 4 is a front cross-sectional view schematically showing a connection structure 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 anisotropic conductive material according to the present invention contains a binder resin, at least first conductive particles whose outer surface is solder, and second particles. The average particle size of the second particles is smaller than the average particle size of the first conductive particles. In 100% of the total number of the first conductive particles, the ratio of the number of the first conductive particles having a particle size smaller than the average particle size of the second particles is 20% or less.

  By adopting the above-described configuration in the anisotropic conductive material according to the present invention, it was obtained when a connection structure was obtained by electrically connecting the electrodes using the anisotropic conductive material according to the present invention. Even when the connection structure is exposed to high temperature and high humidity, sufficient insulation can be secured. That is, the insulation reliability under high temperature and high humidity in the connection structure is increased. This is because, in the connection structure, the first conductive particles act so as to connect the upper and lower electrodes, and the second particles act so as to secure a gap between the upper and lower electrodes. This is thought to be due to the suppression of solder protrusion.

  In order to increase the insulation reliability under high temperature and high humidity in the connection structure, the first conductive particles having a particle diameter smaller than that of the second particles in 100% of the total number of the first conductive particles. The ratio of the number of is 20% or less. Therefore, the relatively small first conductive particles are present in a region where insulation between the upper and lower electrodes connected by the conductive particles and the upper and lower electrodes connected by the adjacent conductive particles is necessary. The number of conductive particles to be reduced can be reduced. As a result, the insulation reliability is increased. From the viewpoint of further improving the insulation reliability under high temperature and high humidity in the connection structure, the particle diameter is smaller than the average particle diameter of the second particles in 100% of the total number of the first conductive particles. The ratio of the number of the first conductive particles is preferably 20% or less, more preferably 15% or less, and still more preferably 10% or less.

  The first conductive particles, the second particles, and the base particles (resin particles and the like) to be described later have a particle size of the first conductive particles, the second particles, and the base particles, respectively. In some cases, it means a diameter, and when each of the first conductive particles, the second particles, and the base particles has a shape other than a spherical shape, the maximum diameter is indicated.

  The “average particle diameter” of base particles (resin particles and the like) described later in the first conductive particles, the second particles, and the first conductive particles indicates a median diameter. The median diameter can be determined using a laser diffraction particle size analyzer. Examples of the laser diffraction particle size measuring device include “SALD-2100” manufactured by Shimadzu Corporation. Regarding the first conductive particles, the second particles, etc. in the anisotropic conductive material, before curing, the particles are dispersed in a solvent, and the particle size distribution is determined using a laser diffraction particle size analyzer. The “average particle size” can be calculated by a method of observing the particle size of each 100 particles with an electron microscope or an optical microscope and obtaining a particle size distribution.

  The average particle size of the second particles is preferably 1 or more times the average particle size of the first conductive particles, more preferably 1.1 times or more, and 1.8 times or less. It is preferable that it is 1.6 times or less. When the average particle diameters of the first conductive particles and the second particles satisfy the above relationship, the insulation reliability at high temperature and high humidity in the connection structure is further increased.

  The anisotropic conductive material according to the present invention is preferably an anisotropic conductive material that can be cured by heating. In this case, it is possible to melt the solder in the conductive particles by heat 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. Is possible.

  In addition, when two kinds of curing agents having different reaction temperatures are used, it is possible to semi-cure the anisotropic conductive material by heating and further to cure the semi-cured anisotropic conductive material by heating.

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

[First conductive particles and second particles]
The first conductive particles are conductive particles whose outer surface is solder. The first conductive particles may be solder particles, and have 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. Some conductive particles may be used. The base particles in the first conductive particles are preferably metal particles having a melting point of 400 ° C. or higher or resin particles having a softening point of 260 ° C. or higher. The base particles in the first conductive particles may be metal particles having a melting point of 400 ° C. or higher, or resin particles having a softening point of 260 ° C. or higher. From the viewpoint of further improving the thermal shock resistance in the connection structure, the base particles in the first conductive particles are preferably resin particles. The softening point of the resin particles in the first conductive particles is preferably higher than the softening point of the solder layer, and preferably higher by 10 ° C. than the softening point of the solder layer. The metal particles having a melting point of 400 ° C. or higher in the first conductive particles and the second particles described later are not particularly limited, and examples thereof include gold, silver, copper, and nickel.

  The second particles are not particularly limited. The second particles are preferably insulating particles or conductive particles having at least an outer surface of solder. The second particles may be insulating particles, or may be conductive particles whose outer surface is solder.

  Each of the first conductive particles and the second particles is a solder particle, or has a base particle and a conductive layer disposed on the surface of the base particle, and at least of the conductive layer It is preferable that the outer surface is a conductive particle which is a solder layer. The second particle may be a solder particle, and includes a base particle and a conductive layer disposed on the surface of the base particle, and at least an outer surface of the conductive layer is a conductive layer. It may be a conductive particle. When the second particles are solder particles, the first conductive particles 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 preferably a conductive particle which is a solder layer.

  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.

  Examples of the substrate particles include resin particles, inorganic particles excluding metals, organic-inorganic hybrid particles, and metal particles. The substrate particles are preferably resin particles, inorganic particles excluding metal, and organic-inorganic hybrid particles, and more preferably resin particles formed of a resin. The base particles in the second particles may be metal particles having a melting point of less than 400 ° C, may be metal particles having a melting point of 400 ° C or higher, and have a softening point of less than 260 ° C. Resin particles may be used, and resin particles having a softening point of 260 ° C. or higher may be used.

  The first conductive particles are solder particles, or have 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. Particles are preferred. From the viewpoint of further improving the thermal shock resistance of the connection structure, the first conductive particles include resin particles and a conductive layer disposed on the surface of the resin particles, and at least outside the conductive layer. It is preferable that the surface is a conductive particle having a solder layer.

  The second particle is a solder particle, or a conductive particle having a resin particle and a conductive layer disposed on the surface of the resin particle, and at least an outer surface of the conductive layer is a solder layer. Preferably there is. From the viewpoint of further improving the connection reliability under high temperature and high humidity by increasing the number of particles connecting the upper and lower electrodes by metal bonding, the second particles are preferably solder particles.

  The first 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 conductive particle that is a solder layer, and More preferably, the second particles are solder particles. In this case, the insulation reliability under high temperature and high humidity in the connection structure is further increased.

  The average particle diameter of the second particles is preferably 1 or more times, more preferably 1.1 or more times the average particle diameter of the base particles (resin particles and the like). It is preferably 8 times or less, and more preferably 1.6 times or less. In this case, it is possible to maintain the gap between the upper and lower electrodes without interfering with the formation of the metal joint by the solder of the first conductive particles, and thus the insulation reliability at high temperature and high humidity in the connection structure is further enhanced. Become.

  In FIG. 1, the electroconductive particle which can be used for the anisotropic electrically-conductive material which concerns on one Embodiment of this invention is shown with sectional drawing. The conductive particles can be used as the first conductive particles or the second particles.

  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. Instead of the resin particles 2, metal particles or the like may be used.

  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. 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. Further, 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.

  Each of the conductive particles 1 and 11 and the solder particles 16 can be used as the first conductive particles and can also be used as the second particles. However, the particle diameters of the conductive particles 1 and 11 and the solder particles 16 used as the first conductive particles and the second particles are set as described above.

  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. Divinylbenzene copolymers such as oxide, polyacetal, polyimide, polyamideimide, polyetheretherketone, polyethersulfone, divinylbenzene polymer, and divinylbenzene-styrene copolymer and divinylbenzene- (meth) acrylate copolymer A polymer etc. are mentioned. 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, the surface of the metal 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) is preferably a filler material having a liquidus of 450 ° C. or less based on JIS Z3001: Welding terms. Examples of the composition of the solder include a metal composition containing zinc, gold, silver, lead, copper, tin, bismuth, indium and the like. Among them, a tin-indium system (117 ° C. eutectic) or a tin-bismuth system (139 ° C. eutectic) which is low-melting and lead-free is preferable. That is, the solder preferably does not contain lead, and is preferably a solder containing tin and indium or a solder containing tin and bismuth.

  Conventionally, the particle diameter of conductive particles having a solder layer as a surface layer outside 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, 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 (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 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 (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.

  Regarding the first conductive particles, the thicknesses of the first conductive layer and the solder layer are preferably 0.5 μm or more, more preferably 1 μm or more, still more preferably 2 μm or more, preferably 20 μm or less, and more. Preferably it is 10 micrometers or less, More preferably, it is 6 micrometers 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 0.5 μm or more with respect to the first conductive particles. Is 1 μm or more, more preferably 2 μm or more, preferably 20 μm or less, more preferably 10 μm or less, and even more preferably 6 μm 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 first conductive particles and the average particle diameter of the base particles (resin particles) in the first conductive particles are preferably 1 μm or more, more preferably 3 μm or more, still more preferably 5 μm or more, preferably Is 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 and the base 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 becomes sufficiently large, and the aggregated conductivity when forming the conductive layer Particles are hardly formed. 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 in the first conductive particles can be selectively used depending on the electrode size or land diameter of the substrate to be mounted. The following explanation of the particle diameter of the resin particles relates to the particle diameter of the resin particles in the first conductive particles.

  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 2.5 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 is 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. When the first conductive particles are particles in which the base particles are coated with solder, the average particle diameter of the particles excluding the solder layer used for FOB and FOF applications is preferably 3 to 100 μm. When the average particle diameter of the particles excluding the solder layer is 3 μm or more, the thickness of the anisotropic conductive material and the connecting portion disposed between the electrodes is sufficiently increased, and the adhesive force is further increased. When the average particle diameter of the particles is 100 μm or less, a short circuit is more unlikely to occur between adjacent electrodes. When the first conductive particles are solder particles, the average particle diameter of the solder particles is preferably 3 to 100 μm. When the average particle diameter of the solder particles is 3 μm or more, the thickness of the anisotropic conductive material and the connecting portion disposed between the electrodes is sufficiently increased, and the adhesive force is further increased.

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. When the first conductive particles are particles in which a base material particle is coated with a solder layer, the average particle diameter of the particles excluding the solder layer used in flip chip applications is preferably 1 to 15 μm. When the average particle diameter of the particles excluding the solder layer is 1 μm or more, the thickness of the solder layer disposed on the surface of the particles excluding the solder layer can be sufficiently increased, and the electrical connection between the electrodes can be more reliably performed. Can be connected to. When the average particle diameter of the particles is 15 μm or less, short-circuiting between adjacent electrodes is more difficult to occur. When the first conductive particles are solder particles, the average particle diameter of the solder particles is preferably 1 to 15 μm. When the average particle diameter of the solder particles is 1 μm or more, the thickness of the anisotropic conductive material and the connecting portion disposed between the electrodes is sufficiently increased, and the adhesive force is further increased.

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. When the 1st electroconductive particle uses the particle | grains which coat | covered the base material particle | grain with the solder, it is preferable that the average particle diameter of the particle | grains except the solder layer used for a COF use is 1-10 micrometers. When the average particle diameter of the particles excluding the solder layer is 1 μm or more, the thickness of the solder layer disposed on the surface of the particles excluding the solder layer can be sufficiently increased, and the electrical connection between the electrodes can be more reliably performed. Can be connected to. When the average particle diameter of the particles excluding the solder layer is 10 μm or less, a short circuit is more unlikely to occur between adjacent electrodes. When the first conductive particles are solder particles, the average particle diameter of the solder particles is preferably 1 to 10 μm. When the average particle diameter of the solder particles is 1 μm or more, the thickness of the anisotropic conductive material and the connecting portion disposed between the electrodes is sufficiently increased, and the adhesive force is further increased.

  The surface of the conductive particles may be insulated with an insulating material, insulating particles, flux, or the like. It is preferable that the insulating material, the insulating particles, the flux, and the like are removed from the connection portion by being softened and flowed by heat at the time of connection. Thereby, the short circuit between electrodes is suppressed.

  Further, the second particles may be insulating particles. Examples of the insulating particles include resin particles, inorganic particles excluding metals, and organic-inorganic hybrid particles.

  When the second particles are resin particles, examples of the resin for forming the resin particles include the same resins as those for forming the resin particles in the conductive particles.

  In the case where the second particles are inorganic particles, examples of the inorganic material for forming the inorganic particles include silica and carbon black.

  Examples of the organic / inorganic hybrid particles include organic / inorganic hybrid particles formed of a crosslinked alkoxysilyl polymer and an acrylic resin.

  The CV value of the particle diameter of the first conductive particles is preferably 40% or less, more preferably 30% or less, and still more preferably 20% or less. When the CV value of the first conductive particles is less than or equal to the above upper limit, the variation in the distance between the electrodes connected by the first conductive particles is reduced, and further, the insulation reliability under high temperature and high humidity in the connection structure The nature becomes even higher.

  The CV value of the particle diameter of the second particles is preferably 40% or less, more preferably 30% or less, and still more preferably 20% or less. When the CV value of the second particles is not more than the above upper limit, the insulation reliability of the connection structure under high temperature and high humidity is further increased. The CV value of the particle diameter is expressed by the following formula.

  CV value of particle diameter (%) = standard deviation of particle diameter / average particle diameter × 100

  When the base particles in the first and second conductive particles are resin particles, the compression elastic modulus (10% K value) at 23 ° C. when the resin particles are 10% compressively deformed is preferably 1 GPa or more, more preferably 2 GPa or more, preferably 7 GPa or less, more preferably 5 GPa or less. When the 10% K value is not less than the above lower limit and not more than the above upper limit, the insulation reliability at high temperature and high humidity in the connection structure is further increased, and the thermal shock characteristics in the connection structure are further improved. .

  The compression elastic modulus (10% K value) at 23 ° C. of the resin particles is measured as follows.

  Using a micro-compression tester, resin particles are compressed under the conditions of a compression rate of 2.6 mN / sec and a maximum test load of 10 g with the end face of a diamond cylinder having a diameter of 50 μm. The load value (N) and compression displacement (mm) at this time are measured. From the measured value obtained, the compression elastic modulus can be obtained by the following formula. As the micro compression tester, for example, “Fischer Scope H-100” manufactured by Fischer is used.

10% K value (N / mm ² ) = (3/2 ^1/2 ) · F · S ⁻³ / ² · R ^−1/2
F: Load value when the resin particles are 10% compressively deformed (N)
S: Compression displacement (mm) when the resin particles are 10% compressively deformed
R: radius of resin particles (mm)

  The compression elastic modulus universally and quantitatively represents the hardness of the conductive particles. By using the compression elastic modulus, the hardness of the resin particles can be expressed quantitatively and uniquely.

  In 100% by weight of the anisotropic conductive material, the content of the first conductive particles is preferably 1% by weight or more, more preferably 2% by weight or more, further preferably 10% by weight or more, preferably 50% by weight. Hereinafter, it is more preferably 45% by weight or less. When the content of the first conductive particles is not less than the above lower limit and not more than the 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.

  In 100% by weight of the anisotropic conductive material, the content of the second particles is preferably 1% by weight or more, more preferably 3% by weight or more, still more preferably 10% by weight or more, preferably 50% by weight or less. More preferably, it is 40% by weight or less. When the content of the second particles is not less than the above lower limit and not more than the upper limit, the insulation reliability under high temperature and high humidity in the connection structure is further increased.

  Ratio of the content (wt%) of the second particles in the anisotropic conductive material to the content (wt%) of the first conductive particles (content of second particles / first conductivity) The content of the particles) is preferably 0.05 or more, more preferably 0.1 or more, still more preferably 0.12 or more, preferably 2 or less, more preferably 1 or less, still more preferably 0.8 or less. When the contents of the first conductive particles and the second particles satisfy the above relationship, when exposed to high temperature and high humidity, cracks in the solder portion in the connection structure and connection resistance between the electrodes Rise is further suppressed.

[Binder resin]
The binder resin preferably contains a thermoplastic compound or contains a curable compound and a thermosetting agent. 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.

  Moreover, it is preferable that the said anisotropic conductive material contains 2 or more types of thermosetting agents from which reaction start temperature differs. Moreover, it is preferable that the thermosetting agent whose reaction start temperature is a low temperature side is a thermal radical generator.

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

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

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

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

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

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

  The curable compound is preferably a reaction product of a compound having two or more epoxy groups or two or more thiirane groups and (meth) acrylic acid. This reaction product is obtained by reacting a compound having two or more epoxy groups or two or more thiirane groups with (meth) acrylic acid in the presence of a basic catalyst or the like 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 improving the 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.

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

  Examples of the thermosetting agent include imidazole curing agents, amine curing agents, phenol curing agents, polythiol curing agents, thermal cation generators, acid anhydrides, and thermal radical generators. Among them, an imidazole curing agent, a polythiol curing agent, or an amine curing agent is preferable because the anisotropic 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. As for these thermosetting agents, only 1 type may be used and 2 or more types may be used together. In addition, the said thermosetting agent may be coat | covered with polymeric substances, such as a polyurethane resin or a polyester resin.

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

  The 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 thermal 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 removing the oxide film formed on the solder surface or the electrode surface, facilitating the formation of a metal bond with the upper and lower electrodes, and further enhancing the connection reliability, the thermosetting agent includes a thermal cation generator. It is preferable.

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

  When the thermosetting agent contains a thermal cation generator, the content of the thermal cation generator is preferably 0.01 parts by weight or more with respect to 100 parts by weight of the curable compound curable by heating. More preferably it is 0.05 parts by weight or more, preferably 10 parts by weight or less, more preferably 5 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 curable composition is sufficiently thermally cured.

  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 preferably contains a thermal radical generator. The thermal radical generator is not particularly limited. As the thermal radical generator, a conventionally known thermal radical generator can be used. By using the thermal radical generator, the conduction reliability between the electrodes and the connection reliability of the connection structure are further enhanced. As for the said thermal radical generator, only 1 type may be used and 2 or more types may be used together.

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

  The content of the thermal radical generator is preferably 0.1 parts by weight or more, more preferably 0.2 parts by weight or more, preferably 5 parts by weight or less based on 100 parts by weight of the curable compound curable by heating. More preferably, it is 3 parts by weight or less. When the content of the thermal radical generator is not less than the above lower limit and not more than the above upper limit, the anisotropic conductive material can be appropriately thermally cured. By making the anisotropic conductive material into a B-stage, the flow of the anisotropic conductive material can be suppressed, and the generation of voids during bonding can be further suppressed.

  The anisotropic conductive material according to the present invention 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 anisotropic conductive material does not necessarily contain a flux.

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

  Examples of the molten salt include ammonium chloride. Examples of the organic acid include lactic acid, citric acid, stearic acid, 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 having a carboxyl group bonded to an alkyl chain include hexanoic acid (5 carbon atoms, 1 carboxyl group), glutaric acid (4 carbon atoms, 2 carboxyl groups), 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.

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

  The anisotropic conductive material preferably contains a filler. By using the filler, the coefficient of thermal expansion of the cured anisotropic conductive material is lowered. 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 elastic modulus of the cured product obtained by curing the anisotropic conductive material is preferably 100 MPa or more, preferably 5 GPa or less at 25 ° C., and further preferably 10 MPa or more, preferably 3 GPa or less at 85 ° C. When the elastic modulus is not less than the above lower limit and not more than the above upper limit, connection reliability when receiving a thermal history is increased.

  The glass transition temperature Tg of the cured product obtained by curing the anisotropic conductive paste is preferably 60 ° C. or higher, more preferably 85 ° C. or higher, and preferably 180 ° C. or lower. When the glass transition temperature is not less than the above lower limit and not more than the above upper limit, the connection reliability of the connection structure when receiving a thermal history is increased.

  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, when the anisotropic conductive material according to the present invention contains a thermal cation generator or flux, the oxide film on the surface of the copper electrode can be effectively removed, and the conduction reliability in the connection structure is improved. be able to.

  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. 4 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.

  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 connection part 24 is formed of an anisotropic conductive material including the conductive particles 1 and the resin particles 31. Here, the conductive particles 1 are used as the first conductive particles, and the resin particles 31 are used as the second particles.

  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 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 said pressurization is about 9.8 * 10 < ⁴ > -4.9 * 10 < ⁶ > Pa. The temperature of the said heating is about 120-220 degreeC.

  FIG. 5 is an enlarged front sectional view of a connection portion between the conductive particles 1 and the first and second electrodes 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. Further, the first conductive layer 4 can be brought into contact with the first electrode 22b and 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.

  The metal constituting at least one of the first electrode and the second electrode is preferably capable of forming an alloy with solder. The metal constituting both the first electrode and the second electrode is preferably capable of forming an alloy with solder. The metal capable of forming an alloy with the solder is preferably copper, aluminum or silver. In this case, the thermal shock resistance in the connection structure is further improved.

  In the obtained connection structure, the maximum thickness of the alloy layer formed by the solder and the electrode at the contact portion between the electrode and the solder is the thickness of the solder layer disposed between the electrode and the base particle. It is preferable that it is 1/2 or more. In this case, the thermal shock resistance in the connection structure is further improved.

  When the base particles in the first conductive particles are resin particles, in the obtained connection structure, the particle diameter in the compression direction of the resin particles in the first conductive particles is the resin particle before compression. It is preferable that it is 4/5 or more. In this case, the thermal shock resistance in the connection structure is further improved.

  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.

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

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

(Binder resin)
Thermoplastic compound 1:
In a 3 L separable flask, 219 g of Pripol 1009 (HOOC- (CH ₂ ) ₃₄ —COOH, molecular weight 567, manufactured by Croda Japan Co., Ltd.), 5 g of ethylenediamine (NH ₂ CH ₂ CH ₂ NH ₂ , molecular weight 60), piperazine ( 27 g of C ₄ H ₁₀ N ₂ , molecular weight 86) and 0.8 g of 5% aqueous phosphorous acid solution were added.

  A water separation tube was attached, the temperature was raised to 190 ° C. with stirring under a nitrogen flow, and a polycondensation reaction was performed until the number average molecular weight of the reaction product reached 1400. Thereafter, 83 g of dodecanedioic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) was added and stirred at 190 ° C. until the contents became transparent. Thereafter, 358 g of polytetramethylene ether glycol (“PTMG1000” manufactured by Mitsubishi Chemical Corporation, number average molecular weight 1000) and 1 g of Irganox 1098 (manufactured by BASF Japan) were added and stirred until they were even. Thereafter, 0.1 g of antimony trioxide and 0.1 g of monobutylhydroxytin oxide were added, the temperature was raised to 250 ° C., and the mixture was stirred for 30 minutes. The pressure was reduced to 1 mmHg, and the reaction was further performed at 250 ° C. for 4 hours. As a result, a polyamide / polyester block polymer having a number average molecular weight of 28000 and a melting point of 120 ° C. was obtained. This polyamide / polyester block polymer is referred to as thermoplastic compound 1.

Thermosetting compound 1 (epoxy group-containing acrylic resin, "Blemmer CP-30" manufactured by Mitsubishi Chemical Corporation)
Thermosetting compound 2 (bisphenol A type epoxy compound, “YL980” manufactured by Mitsubishi Chemical Corporation)
Thermosetting compound 3 (resorcinol type epoxy compound, “EX-201” manufactured by Nagase ChemteX Corporation)
Thermosetting compound 4 (CTBN modified epoxy resin, “EPR-4023” manufactured by ADEKA)

Thermosetting agent A (imidazole compound, “2P-4MZ” manufactured by Shikoku Kasei Kogyo Co., Ltd.)
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)

Adhesion imparting agent: “KBE-403” manufactured by Shin-Etsu Chemical Co., Ltd.
Flux: “Glutaric acid” manufactured by Wako Pure Chemical Industries, Ltd.

(particle)
The average particle diameter of the particles indicates the median diameter.

Conductive particles 1: SnBi solder particles (“DS-10” manufactured by Mitsui Kinzoku Co., Ltd., average particle size: 12 μm)
Conductive particles 2: SnBi solder particles (“Mitsui Kinzoku Co., Ltd.“ ST-5 ”, average particle size 5 μm)
Conductive particles 3: SnBi solder particles ("Sn58Bi-20" manufactured by Fukuda Metals Co., Ltd., average particle size: 4.5 μm)
Conductive particles 4: SnBi solder particles (“Sn58Bi-20” manufactured by Fukuda Metals Co., Ltd., average particle size: 4.5 μm) are divided by a precision sieve with an opening of 4 μm, and the ratio of the number of particles less than 3 μm is 19%. Conductive particles

Conductive particles 5:
(Resin core solder coated particles, prepared by the following procedure)
Divinylbenzene resin particles (“Micropearl SP-210” manufactured by Sekisui Chemical Co., Ltd., average particle diameter 10 μm, softening point 330 ° C., 10% K value (23 ° C.) 3.8 GPa) are electroless nickel plated, A base nickel plating layer having a thickness of 0.1 μm was formed on the surface. 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 (average particle size 14 μm, CV value 22%, resin core solder-coated particles) were prepared.

  In addition, the following conductive particles 6 to 8 were obtained in the same manner as the conductive particles 5 except that the type of the base particles, the average particle diameter of the base particles, the thickness of the copper layer, and the thickness of the solder layer were changed. It was.

Conductive particles 6 (divinylbenzene resin particles, average particle diameter of resin particles 10 μm, resin particle 10% K value (23 ° C.) 3.8 GPa, resin particle softening point 330 ° C., copper layer thickness 1 μm, solder layer (Thickness 2μm, average particle diameter of conductive particles 16μm, CV value 26%)
Conductive particles 7 (divinylbenzene resin particles, average particle diameter of resin particles 16 μm, resin particle 10% K value (23 ° C.) 3.6 GPa, resin particle softening point 330 ° C., copper layer thickness 1 μm, solder layer (Thickness 2μm, average particle diameter of conductive particles 22μm, CV value 25%)
Conductive particles 8: SnBi solder particles (“10-25” manufactured by Mitsui Kinzoku Co., Ltd., average particle size 21 μm)
m)

Conductive particles 9:
(Copper core solder coated particles, prepared by the following procedure)
Using copper particles (“PF-7F” manufactured by Epson Atmix Co., Ltd., average particle diameter of 4 μm) and using an electroplating solution containing tin and bismuth, the surface of the copper particles is electroplated, and the solder has a thickness of 2 μm. A layer was formed. Conductive particles (average particle diameter 8 μm, CV value 30%, copper core solder coated particles) in which a solder layer (tin: bismuth = 43 wt%: 57 wt%) having a thickness of 2 μm is formed on the surface of the copper particles Produced.

Insulating particles 1: Divinylbenzene particles ("Micropearl SP-210" manufactured by Sekisui Chemical Co., Ltd., average particle size 10 μm, softening point 330 ° C., 10% K value (23 ° C.) 3.8 GPa, CV value 5%)
Insulating particles 2: Divinylbenzene particles (“Micropearl SP-203” manufactured by Sekisui Chemical Co., Ltd., average particle diameter 3 μm, softening point 330 ° C., 10% K value (23 ° C.) 5.2 GPa, CV value 7%)
Insulating particles X: silica particles (manufactured by Ube Nitto Kasei Co., Ltd., average particle size 10 μm, CV value 3%)
Insulating particles Y: silica particles (manufactured by Ube Nitto Kasei Co., Ltd., average particle size 3 μm, CV value 3%)

(Examples 1 to 26 and Comparative Examples 1 to 6)
The components shown in Tables 1 to 3 below were blended in the blending amounts shown in Tables 1 to 3 to obtain anisotropic conductive pastes. For Example 1, the blending amount was expressed as solid content.

(Evaluation)
(1) The ratio (%) of the number of first conductive particles whose particle diameter is smaller than the average particle diameter of the second particles in 100% of the total number of first conductive particles
The particle size distribution of the first conductive particles was measured using a laser diffraction particle size analyzer (“SALD-2100” manufactured by Shimadzu Corporation). From the obtained particle size distribution, the ratio (%) of the number of first conductive particles having a particle diameter smaller than the average particle diameter of the second particles in the total number of 100% of the first conductive particles was determined. .

(2) Preparation of connection structure The glass epoxy board | substrate (FR-4 board | substrate) which has a copper electrode pattern whose L / S is 100 micrometers / 100 micrometers on the upper surface was prepared. Moreover, the flexible printed circuit board which has a copper electrode pattern with L / S of 100 micrometers / 100 micrometers on 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 becomes 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 to melt the solder. The anisotropic conductive material layer was cured at 185 ° C. to obtain a connection structure.

(3) Conduction test between upper and lower electrodes The connection resistance between the upper and lower electrodes of the connection structure obtained in (2) Preparation of the 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]
○○: 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) Moisture and heat resistance The moisture and heat resistance was evaluated by a bias test. Specifically, a glass epoxy substrate (FR-4 substrate) having a comb-shaped copper electrode pattern with an L / S of 100 μm / 100 μm on the upper surface was prepared. Moreover, the flexible printed circuit board which has a comb-shaped copper electrode pattern whose L / S is 100 micrometers / 100 micrometers on the lower surface was prepared. A connection structure was obtained under the same conditions as in (2) above.

  Under the conditions of 85 ° C. and 85% relative humidity, 15 V was applied between adjacent electrodes of the obtained connection structure for 500 hours. After 500 hours, the resistance value between adjacent electrodes was measured under an atmosphere of 85 ° C. and 85%. Wet heat resistance was determined according to the following criteria.

[Criteria for wet heat resistance]
○○: Resistance value is 10 ⁸ Ω or more ○: Resistance value is 10 ⁷ Ω or more, less than 10 ⁸ Ω ×: Resistance value is less than 10 ⁷ Ω

(5) Thermal shock resistance test Each of the obtained connection structures 20 was prepared, held at −30 ° C. for 5 minutes, then heated to 80 ° C., held for 5 minutes, and then cooled to −30 ° C. A cooling cycle test was performed in which the process was 1 cycle and 1 hour per cycle. 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

(6) Elastic modulus at 25 ° C. and glass transition temperature Tg of the cured layer obtained by curing the anisotropic conductive material
The elastic layer at 25 ° C. and the glass transition temperature Tg of the cured product layer and the cured insulating layer obtained by curing the anisotropic conductive material layer in the connection structure were prepared as a sample having a width of 3 mm × length of 15 mm × thickness of 0.1 mm. Then, using a viscoelasticity measuring device ("DVA-200" manufactured by IT Measurement & Control Co., Ltd.), the temperature was increased at a rate of 5 ° C / min, the deformation rate was 0.1% and 10 Hz. The temperature at the peak of tan δ was defined as Tg (glass transition temperature).

  The results are shown in Tables 1 to 3 below. In the following Tables 1 to 3, “1>” indicates “less than 1”.

  In the connection structure using the anisotropic conductive material of Examples 1 to 25 in which the base particles in the first conductive particles are resin particles, the compression direction of the resin particles in the first conductive particles The particle diameter of was 4/5 or more of the resin particles before compression.

  In addition, in the connection structure using the anisotropic conductive material of Examples 1 to 26, the maximum thickness of the alloy layer formed by the solder and the electrode in the contact portion between the electrode and the solder is the electrode and the base particle. It was 1/2 or more of the maximum thickness of the solder layer arrange | positioned between.

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 ... Upper surface 22b ... First electrode 23 ... Second connection object member 23a ... Lower surface 23b ... Second electrode 24 ... Connection part 31 ... Resin particles

Claims (10)

A binder resin,
First conductive particles having at least an outer surface made of solder;
Containing second particles,
The average particle size of the second particles is smaller than the average particle size of the first conductive particles,
Anisotropy in which the ratio of the number of the first conductive particles having a particle size smaller than the average particle size of the second particles is 20% or less in the total number of 100% of the first conductive particles. Conductive material.   2. The anisotropic conductive material according to claim 1, wherein an average particle diameter of the second particles is ¼ or more and 9/10 or less of an average particle diameter of the first conductive particles.   The first conductive particles are solder particles or have 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. The anisotropic conductive material according to claim 1, wherein the anisotropic conductive material is a particle.   The first conductive particles are conductive particles having 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. Or the anisotropic conductive material of 2.   The average particle diameter of the second particles is 1 to 1.8 times the average particle diameter of the resin particles in the first conductive particles. The anisotropic conductive material as described.   The anisotropic conductive material according to any one of claims 1 to 5, wherein the second particle is an insulating particle, or at least an outer surface is a conductive particle made of solder.   The anisotropic conductive material according to claim 1, wherein the second particles are solder particles.   The anisotropic conductive material according to claim 1, wherein the binder resin contains a thermoplastic compound, or contains a curable compound that can be cured by heating and a thermosetting agent.   The anisotropic conductive material according to claim 8, wherein the thermosetting agent includes a thermal cation generator. 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 connecting portion connecting the first and second connection target members;
The connection part is formed of the anisotropic conductive material according to any one of claims 1 to 9,
A connection structure in which the first electrode and the second electrode are electrically connected by the first conductive particles.

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