JP2013054850A - Anisotropic conductive material, method of manufacturing the same, and connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anisotropic conductive material capable of effectively removing a binder resin between a conductive particle and an electrode and enhancing conduction reliability when used for electrical connection between electrodes.SOLUTION: An anisotropic conductive material contains a conductive particle 1 and a binder resin. The conductive particle 1 includes: a base particle 2; a first solder layer 4 disposed on a surface 2a of the base particle 2; and a second solder layer 5 laminated on a surface 4a of the outside of the first solder layer 4. The content of an oxygen atom in 100 wt% of the second solder layer 5 is larger than that of the oxygen atom in 100 wt% of the first solder layer 4.

Description

  The present invention relates to an anisotropic conductive material including a plurality of conductive particles, and more particularly, for example, electrical connection between electrodes of various connection target members such as a flexible printed board, a glass substrate, a glass epoxy substrate, and a semiconductor chip. TECHNICAL FIELD The present invention relates to an anisotropic conductive material that can be used for connection, a method for manufacturing the anisotropic conductive material, and a connection structure using the anisotropic conductive material.

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

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

  As an example of the anisotropic conductive material, 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 a solder paste composition containing a solder alloy powder, a thermoplastic resin powder having a melting point lower than that of the solder alloy, and a flux.

  Patent Document 3 below discloses an anisotropic conductive paste containing an epoxy adhesive having a flux action and SnBi solder powder. In patent document 3, the epoxy adhesive containing an epoxy resin, a hardening | curing agent, and an organic acid is mentioned as an epoxy adhesive which has a flux effect | action. Examples of the organic acid include dibasic acids having an alkyl group in the side chain.

JP 2006-108523 A JP 2010-269356 A JP 2006-199937 A

  For example, when electrically connecting an electrode of a semiconductor chip and an electrode of a glass substrate with a conventional anisotropic conductive material, an anisotropic conductive material containing conductive particles and a binder resin on the glass substrate Place. Next, the semiconductor chips are stacked, and a thermocompression bonding head is pressed against the upper surface of the semiconductor chip to heat and pressurize. As a result, the anisotropic conductive material is cured, and the electrodes are electrically connected via the conductive particles to obtain a connection structure.

  In the conventional anisotropic conductive materials described in Patent Documents 1 to 3, since the surface of the solder layer is relatively soft, when the electrodes are electrically connected, a binder resin between the conductive particles and the electrodes is used. It may not be able to be eliminated sufficiently. For this reason, the conduction | electrical_connection reliability between the electrodes connected by the electroconductive particle may be low.

  The object of the present invention is to provide an anisotropic conductive material that can effectively eliminate the binder resin between the conductive particles and the electrode and enhance the conduction reliability when used for electrical connection between the electrodes. It is to provide a material, a manufacturing method of the anisotropic conductive material, and a connection structure using the anisotropic conductive material.

  A limited object of the present invention is to effectively remove the oxide film on the outer surface of the solder layer of the conductive particles and the oxide film on the electrode surface, and improve the conduction reliability between the electrodes connected by the conductive particles. An anisotropic conductive material that can be manufactured, a method for producing the anisotropic conductive material, and a connection structure using the anisotropic conductive material.

  According to a wide aspect of the present invention, the conductive particles include conductive particles and a binder resin, and the conductive particles are base particles, a first solder layer disposed on the surface of the base particles, A second solder layer laminated on the outer surface of the first solder layer, wherein the content of oxygen atoms in 100% by weight of the second solder layer is 100% by weight of the first solder layer. An anisotropic conductive material having a content greater than the oxygen atom content therein is provided.

  In a specific aspect of the anisotropic conductive material according to the present invention, the oxygen atom content in 100% by weight of the second solder layer is the oxygen atom content in 100% by weight of the first solder layer. More than 0.5% by weight.

  In another specific aspect of the anisotropic conductive material according to the present invention, the content of oxygen atoms in 100% by weight of the second solder layer is 1.5% by weight or more and 5.0% by weight or less, The content of oxygen atoms in 100% by weight of the first solder layer is 0.5% by weight or less.

  In another specific aspect of the anisotropic conductive material according to the present invention, a thermal cation generator that releases inorganic acid anions by heating or releases organic acid anions containing boron atoms by heating is further included. .

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

  In still another specific aspect of the anisotropic conductive material according to the present invention, the conductive particles further include a conductive layer disposed between the base particle and the first solder layer, The conductive layer is laminated on the surface of the material particles, and the first solder layer is laminated on the outer surface of the conductive layer.

  In another specific aspect of the anisotropic conductive material according to the present invention, the base particle is a resin particle.

  The anisotropic conductive material according to the present invention is preferably a paste-like anisotropic conductive paste. 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.

Further, according to a wide aspect of the present invention, the method includes a mixing step of mixing the conductive particles and the binder resin, and the conductive particles are the base particles and the first particles disposed on the surface of the base particles. 1 solder layer and a second solder layer laminated on the outer surface of the first solder layer, and the content of oxygen atoms in 100% by weight of the second solder layer is as described above. There is provided a method for producing an anisotropic conductive material using conductive particles having a content higher than the content of oxygen atoms in 100% by weight of the first solder layer.

  In a specific aspect of the method for producing an anisotropic conductive material according to the present invention, when the first and second solder layers are formed before the mixing step, the second solder layer is 100% by weight. Forming the first and second solder layers such that the content of oxygen atoms in the first solder layer is greater than the content of oxygen atoms in 100% by weight of the first solder layer; The conductive particles comprising the first and second solder layers are obtained, or the oxidized particles comprising the base material particles and the first and second solder layers are used for the oxidation. Oxidation of the second solder layer of the previous conductive particles is allowed to proceed so that the content of oxygen atoms in 100% by weight of the second solder layer is changed to oxygen atoms in 100% by weight of the first solder layer. The conductivity is higher than the content of the base material and includes the base particle and the first and second solder layers. Obtaining a child is further provided.

  In another specific aspect of the method for producing an anisotropic conductive material according to the present invention, in the mixing step, the conductive particles, the binder resin, and inorganic acid anions are released by heating or boron by heating. A thermal cation generator that releases organic acid anions containing atoms is mixed.

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

  In the connection structure according to the present invention and the method for manufacturing the connection structure according to the present invention, the first connection target member has a first electrode on the upper surface, and the second connection target member is second on the lower surface. It is preferable that the first electrode and the second electrode are electrically connected by the conductive particles. In the connection structure according to the present invention and the method for manufacturing the connection structure according to the present invention, it is preferable that at least one of the first electrode and the second electrode is a copper electrode.

  The anisotropic conductive material according to the present invention includes conductive particles and a binder resin, and the conductive particles are base particles, a first solder layer disposed on the surface of the base particles, and the first And a second solder layer laminated on the outer surface of the first solder layer, and the content of oxygen atoms in 100% by weight of the second solder layer is 100% by weight of the first solder layer. %, The binder resin between the conductive particles and the electrode can be effectively eliminated when the electrodes are electrically connected. For this reason, the conduction | electrical_connection reliability between the electrodes connected by the electroconductive particle can be improved.

  In the method for producing an anisotropic conductive material according to the present invention, the base particle, the first solder layer disposed on the surface of the base particle, and the outer surface of the first solder layer are laminated. A second solder layer, and a conductive material having a content of oxygen atoms in 100% by weight of the second solder layer larger than a content of oxygen atoms in 100% by weight of the first solder layer. Since it has a mixing step of mixing particles and binder resin, the binder resin between the conductive particles and the electrode is effective when the obtained anisotropic conductive material is used to electrically connect the electrodes. Can be eliminated. For this reason, the conduction | electrical_connection reliability between the electrodes connected by the electroconductive particle can be improved.

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

  Hereinafter, the present invention will be described in detail.

  The anisotropic conductive material according to the present invention includes conductive particles and a binder resin. The conductive particles include base particles, a first solder layer disposed on the surface of the base particles, and a second solder layer stacked on the outer surface of the first solder layer. Is provided. The content of oxygen atoms in 100% by weight of the second solder layer is larger than the content of oxygen atoms in 100% by weight of the first solder layer.

  The method for producing an anisotropic conductive material according to the present invention includes a mixing step of mixing conductive particles and a binder resin. In the method for producing an anisotropic conductive material according to the present invention, the base particles, the first solder layer disposed on the surface of the base particles, and the outer layer of the first solder layer are stacked. The second solder layer is conductive, and the content of oxygen atoms in 100% by weight of the second solder layer is higher than the content of oxygen atoms in 100% by weight of the first solder layer. Sex particles are used.

  In the anisotropic conductive material according to the present invention and the method for producing the anisotropic conductive material according to the present invention, the first and first conductive particles used together with the binder resin are disposed on the surface of the base particle. 2, and the content of oxygen atoms in the second solder layer is greater than the content of oxygen atoms in the first solder layer, so that the second solder layer is the first solder layer. It is harder to oxidize than the solder layer and has a relatively high hardness. For this reason, when the electrodes are electrically connected using an anisotropic conductive material, the binder resin between the conductive particles and the electrodes can be effectively eliminated. For this reason, the conduction | electrical_connection reliability between the electrodes connected by the electroconductive particle can be improved.

  Furthermore, since the content of oxygen atoms in the first solder layer is less than the content of oxygen atoms in the second solder layer, the first solder layer is brought into contact with the electrodes when connecting the electrodes. As a result, the connection resistance between the electrodes can be lowered. This also increases the reliability of conduction between the electrodes.

  The content of oxygen atoms in 100% by weight of the second solder layer is preferably 0.1% by weight or more than the content of oxygen atoms in 100% by weight of the first solder layer. More preferably, it is more than 1.0% by weight, more preferably more than 1.0% by weight, particularly preferably more than 1.5% by weight. When the content of oxygen atoms in the second solder layer is larger, the outer surface of the second solder layer becomes harder. Therefore, when the electrodes are electrically connected using an anisotropic conductive material, The binder resin between the conductive particles and the electrode can be more effectively eliminated. On the other hand, at the time of connection, the electrodes are connected by conductive particles by melting the first and second solder layers and bringing the electrodes into contact with the first solder layer having a relatively small oxygen atom content. The conduction reliability between them can be further enhanced.

The content of oxygen atoms in 100% by weight of the second solder layer is preferably 0.5% by weight or more, more preferably 1.0% by weight or more, still more preferably 1.5% by weight or more, preferably 10% by weight. % Or less, more preferably 5% by weight or less. The content of oxygen atoms in 100% by weight of the first solder layer is preferably 1.5% by weight or less, more preferably 1.0% by weight or less, and still more preferably 0.5% by weight or less. The first solder layer may not contain oxygen atoms. When the content of oxygen atoms in the first and second solder layers is not less than the above lower limit and not more than the above upper limit, the outer surface of the second solder layer is sufficiently hard, so an anisotropic conductive material is used. When the electrodes are electrically connected, the binder resin between the conductive particles and the electrodes can be further effectively eliminated. On the other hand, at the time of connection, the first and second solder layers are melted, and the electrodes are also brought into contact with the first solder layer having a low oxygen atom content. The conduction reliability can be further improved. From the viewpoint of further improving the exclusion property of the binder resin and further improving the conduction reliability between the electrodes, the content of oxygen atoms in 100% by weight of the second solder layer is 1.5% by weight or more, 5 It is particularly preferable that the oxygen atom content is not more than 0.0% by weight, and the oxygen atom content in 100% by weight of the first solder layer is not more than 0.5% by weight.

  When the first and second solder layers are formed, the oxygen atom content in 100% by weight of the second solder layer is greater than the oxygen atom content in 100% by weight of the first solder layer. Forming the first and second solder layers so as to increase the number of the conductive particles provided with the base particles and the first and second solder layers, or obtaining the base particles And the first and second solder layers are used to conduct oxidation of the second solder layer of the conductive particles before oxidation using the conductive particles before oxidation. The content of oxygen atoms in wt% is made larger than the content of oxygen atoms in 100 wt% of the first solder layer, and the base particles and the first and second solder layers are provided. It is preferable to obtain the conductive particles. When the first and second solder layers are formed, the oxygen atom content in 100% by weight of the second solder layer is greater than the oxygen atom content in 100% by weight of the first solder layer. It is more preferable to form the first and second solder layers so as to increase the number of the conductive particles including the base material particles and the first and second solder layers. Moreover, it is preferable that the second solder layer is formed separately from the first solder layer after the first solder layer is formed. After the first solder layer is formed, the second solder layer is preferably formed separately from the first solder layer.

  The anisotropic conductive material according to the present invention preferably contains a thermal cation generator that releases inorganic acid anions by heating or releases organic acid anions containing boron atoms by heating. In the mixing step in the method for producing an anisotropic conductive material according to the present invention, the conductive particles, the binder resin, and inorganic acid anions are released by heating, or organic acid anions containing boron atoms are released by heating. It is preferable to mix a thermal cation generator. In the anisotropic conductive material according to the present invention and the method for producing the anisotropic conductive material according to the present invention, the conductive particles used together with the binder resin and the specific thermal cation generator are on the surface of the base particle. The first solder layer and the second solder layer arranged, and the oxygen content of the second solder layer is higher than the oxygen atom content of the first solder layer, The second solder layer is less likely to be oxidized than the first solder layer, and the oxidation of the second solder layer can be suppressed. That is, since the second solder layer is already oxidized rather than the first solder layer, further progress of oxidation of the second solder layer can be suppressed. For this reason, the conduction | electrical_connection reliability between electrodes can be improved.

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

(Conductive particles)
In FIG. 1, the electroconductive particle contained in the anisotropic electrically-conductive material which concerns on the 1st Embodiment of this invention is shown with sectional drawing.

  A conductive particle 1 shown in FIG. 1 includes a base particle 2, a conductive layer 3, a first solder layer 4, and a second solder layer 5. The content of oxygen atoms in 100% by weight of the second solder layer 5 is larger than the content of oxygen atoms in 100% by weight of the first solder layer 4.

  The conductive layer 3 is laminated on the surface 2 a of the base particle 2. The conductive layer 3 covers the surface 2 a of the base particle 2. The conductive layer 3 has a single layer structure. The conductive layer 3 is an inner layer.

  The first solder layer 4 is disposed on the surface 2 a of the base particle 2. The first solder layer 4 is disposed on the surface 2 a of the base particle 2 via the conductive layer 3. The first solder layer 4 is laminated on the outer surface 3 a of the conductive layer 3. The first solder layer 4 covers the outer surface 3 a of the conductive layer 3. The first solder layer 4 is an intermediate layer.

  The second solder layer 5 is laminated on the outer surface 4 a of the first solder layer 4. The second solder layer 5 covers the outer surface 4 a of the first solder layer 4. The second solder layer 5 is an outer layer.

  In FIG. 2, the electroconductive particle contained in the anisotropic conductive material which concerns on the 2nd Embodiment of this invention is shown with sectional drawing.

  A conductive particle 11 shown in FIG. 2 includes a base particle 2, a conductive layer 12, a first solder layer 13, and a second solder layer 14. The content of oxygen atoms in 100 wt% of the second solder layer 14 is larger than the content of oxygen atoms in 100 wt% of the first solder layer 13. The conductive particles 11 and the conductive particles 1 differ only in the conductive layer.

  The conductive layer 12 is laminated on the surface 2 a of the base particle 2. The conductive layer 12 covers the surface 2 a of the base particle 2. The conductive layer 12 has a two-layer structure and is a multilayer. The conductive layer 12 has an inner conductive layer 21 (first conductive layer) and an outer conductive layer 22 (second conductive layer). The outer conductive layer 22 is the outermost layer of the conductive layer 12.

  The first solder layer 13 is disposed on the surface 2 a of the base particle 2. The first solder layer 13 is disposed on the surface 2 a of the base particle 2 via the conductive layer 12. The first solder layer 13 is laminated on the outer surface 12 a of the conductive layer 12. The first solder layer 13 is laminated on the surface of the outer conductive layer 22 that is the outermost layer of the conductive layer 12. The first solder layer 13 covers the outer surface 12 a of the conductive layer 12 and the outer surface of the outer conductive layer 22.

  The second solder layer 14 is laminated on the outer surface 13 a of the first solder layer 13. The second solder layer 14 covers the outer surface 13 a of the first solder layer 13.

  From the viewpoint of further reducing the connection resistance between the electrodes, like the conductive particles 1 and 11, the conductive particles are conductive layers arranged between the base material particles and the first solder layer. It is preferable to further comprise. Further, from the viewpoint of further reducing the connection resistance between the electrodes, the conductive particles are formed by laminating the conductive layer on the surface of the base material particle, and the conductive particles are formed on the outer surface of the conductive layer. It is preferable that one solder layer is laminated.

  Like the conductive particles 1 and 11, the conductive layer may have a single-layer structure or a two-layer stacked structure. Furthermore, the conductive layer may have a stacked structure of two or more layers.

Examples of the substrate particles include resin particles, inorganic particles, organic-inorganic hybrid particles, and metal particles.

  The substrate particles are preferably resin particles formed of a resin. When connecting the electrodes, the conductive particles are generally compressed after the conductive particles are arranged between the electrodes. When the substrate particles are resin particles, the conductive particles are easily deformed by compression, and the contact area between the conductive particles and the electrode is increased. For this reason, the conduction | electrical_connection reliability between electrodes becomes high. Furthermore, the flexibility of the conductive particles is increased when the substrate particles are resin particles formed of a resin rather than particles of a metal such as nickel or glass. When the flexibility of the conductive particles is high, damage to the electrode in contact with the conductive particles can be suppressed.

  Examples of the resin for forming the resin particles include polyolefin resin, acrylic resin, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polyethylene terephthalate, polysulfone, and polyphenylene. Examples thereof include oxides, polyacetals, polyimides, polyamideimides, polyetheretherketones, and polyethersulfones. Since the conductive particles can be appropriately deformed by compression, the resin particles are formed of a polymer obtained by polymerizing one or more polymerizable monomers having an ethylenically unsaturated group. Is preferred.

  Examples of the inorganic substance 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.

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

  The conductive layer is preferably made of metal. The metal which comprises the said conductive layer is not specifically limited. Examples of the metal include tin, gold, silver, copper, platinum, palladium, zinc, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium and cadmium, and alloys thereof. It is done. In addition, tin-doped indium oxide (ITO) may be used as the metal. Especially, since it is excellent in electroconductivity, a copper layer, a nickel layer, a gold layer, a silver layer, and a palladium layer are preferable. As for the said metal, only 1 type may be used and 2 or more types may be used together.

  A method of forming the conductive layer on the surface of the substrate particles, a method of forming the first solder layer on the surface of the conductive layer, and the second solder layer on the surface of the first solder layer The method for forming is not particularly limited. As a method for forming the conductive layer and the first and second solder layers, for example, a method by electroless plating, a method by electroplating, a method by physical collision, a method by mechanochemical reaction, physical vapor deposition or physical Examples thereof include a method by adsorption, and a method of coating the surface of resin particles with a paste containing metal powder or metal powder and a binder. Among these, a method using electroless plating, electroplating, or physical collision is preferable. Examples of the method by physical vapor deposition include methods such as vacuum vapor deposition, ion plating, and ion sputtering. Further, in the method based on the physical collision, for example, a theta composer or the like is used.

The method of forming the first solder layer on the surface of the conductive layer and the method of forming the second solder layer on the surface of the first solder layer are methods by physical collision. Is preferred. The first solder layer is preferably laminated on the surface of the conductive layer by physical impact, and the second solder layer is formed on the surface of the first solder layer by physical impact. It is preferable to be laminated.

  In addition, after preparing conductive particles having a solder layer in advance, the conductive particles are allowed to stand under oxygen and warming, so that oxidation of the outer surface of the solder layer proceeds, and the first, first, Two solder layers may be formed. In this case, the heating temperature is preferably 60 ° C. or higher, more preferably 80 ° C. or higher, preferably 200 ° C. or lower, more preferably 180 ° C. or lower.

  When the conductive layer has a single layer structure, the conductive layer is preferably a copper layer, a nickel layer, or a palladium layer, and more preferably a copper layer. Moreover, when the said conductive layer has a laminated structure of two or more layers, it is preferable that the outermost layer of the said conductive layer is a copper layer, a nickel layer, or a palladium layer, and it is more preferable that it is a copper layer. In this case, the connection resistance between the electrodes is further reduced. In addition, a solder layer can be more easily formed on the surface of these preferable conductive layers.

  The conductivity of the copper layer, nickel layer, gold layer, silver layer and palladium layer is higher than the conductivity of the first and second solder layers. For this reason, the conduction | electrical_connection reliability between electrodes becomes high. On the other hand, the copper layer and the palladium layer also have properties that are relatively easily oxidized. However, in the conductive particles, when the conductive layer is a copper layer and a palladium layer, the first and second solder layers are disposed on the surfaces of the copper layer and the palladium layer. The oxidation of the palladium layer can be effectively suppressed.

  Examples of the metal other than tin constituting the first and second solder layers include the metal constituting the conductive layer described above. The first and second solder layers may be alloys. Specific examples of the metal constituting the first and second solder layers include bismuth, silver and indium.

  The thicknesses of the conductive layer and the first and second solder layers are each preferably 10 nm or more, more preferably 50 nm or more, still more preferably 100 nm or more, preferably 2000 nm or less, more preferably 1000 nm or less. The thickness of the second solder layer is more preferably 500 nm or less, and particularly preferably 200 nm or less. When the thickness of the conductive layer and the first and second solder layers is equal to or greater than the above lower limit, the conductivity is sufficiently high. When the thickness of the conductive layer and the first and second solder layers is not more than the above upper limit, the difference in thermal expansion coefficient between the substrate particles, the conductive layer, and the first and second solder layers is reduced, and the conductive layer and The solder layer is unlikely to peel off.

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

  When the conductive layer has a laminated structure of two or more layers, the thickness of the outermost layer of the conductive layer is preferably 5 nm or more, more preferably 10 nm or more, still more preferably 25 nm or more, particularly preferably 50 nm or more, preferably It is 1000 nm or less, More preferably, it is 500 nm or less. When the thickness of the outermost layer of the conductive layer is not less than the above lower limit, the conductivity is sufficiently high. When the thickness of the outermost layer of the conductive layer is not more than the above upper limit, the difference in the coefficient of thermal expansion between the base particles and the outermost layer of the conductive layer becomes small, and the outermost layer of the conductive layer is hardly peeled off.

  The average particle diameter of the conductive particles is preferably 0.1 μm or more, more preferably 1 μm or more, preferably 100 μm or less, more preferably 80 μm or less, still more preferably 50 μm or less, and particularly preferably 40 μm or less. When the average particle diameter of the conductive particles is not less than the above lower limit and not more than the above upper limit, the contact area between the conductive particles and the electrode is sufficiently large, and aggregated conductive particles are formed when the conductive layer is formed. It becomes difficult. Further, the distance between the electrodes connected via the conductive particles does not become too large, and the conductive layer is difficult to peel from the surface of the base material particles.

  Since the size is suitable for the conductive particles in the anisotropic conductive material and the distance between the electrodes can be further reduced, the average particle diameter of the conductive particles is preferably 0.1 μm or more, more preferably Is 100 μm or less, more preferably 50 μm or less.

  The “average particle size” of the conductive particles indicates a number average particle size. The average particle diameter of the conductive particles can be obtained by observing 50 arbitrary conductive particles with an electron microscope or an optical microscope and calculating an average value.

  The conductive particles may include insulating particles disposed on the surface of the second solder layer. The number of the insulating particles arranged on the surface of the second solder layer is preferably plural.

  When the electroconductive particle provided with the said insulating particle is used for the connection between electrodes, the short circuit between adjacent electrodes can be prevented. Specifically, when a plurality of conductive particles are in contact with each other, the insulating particles are present between the plurality of electrodes, so that it is possible to prevent a short circuit between electrodes adjacent in the lateral direction instead of between the upper and lower electrodes. It should be noted that insulating particles between the solder layer and the electrodes in the conductive particles can be easily eliminated by pressurizing the conductive particles with the two electrodes when connecting the electrodes.

  Specific examples of the insulating resin constituting the insulating particles include polyolefins, (meth) acrylate polymers, (meth) acrylate copolymers, block polymers, thermoplastic resins, crosslinked thermoplastic resins, and thermosetting. Resin, water-soluble resin, and the like.

  Examples of the polyolefins include polyethylene, ethylene-vinyl acetate copolymer, and ethylene-acrylic acid ester copolymer. Examples of the (meth) acrylate polymer include polymethyl (meth) acrylate, polyethyl (meth) acrylate, and polybutyl (meth) acrylate. Examples of the block polymer include polystyrene, styrene-acrylic acid ester copolymer, SB type styrene-butadiene block copolymer, SBS type styrene-butadiene block copolymer, and hydrogenated products thereof. Examples of the thermoplastic resin include vinyl polymers and vinyl copolymers. As said thermosetting resin, an epoxy resin, a phenol resin, a melamine resin, etc. are mentioned. Examples of the water-soluble resin include polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyvinyl pyrrolidone, polyethylene oxide, and methyl cellulose. Of these, water-soluble resins are preferable, and polyvinyl alcohol is more preferable.

Examples of the method for attaching insulating particles to the surface of the second solder layer include a chemical method and a physical or mechanical method. Examples of the chemical method include an interfacial polymerization method, a suspension polymerization method in the presence of particles, and an emulsion polymerization method. Examples of the physical or mechanical method include spray drying, hybridization, electrostatic adhesion, spraying, dipping, and vacuum deposition. Especially, since the said insulating particle cannot separate | separate easily, the method of making the said insulating particle adhere to the surface of the said 2nd solder layer through a chemical bond is preferable.

(Binder resin)
The binder resin preferably contains a thermoplastic compound or a curable compound. The binder resin may contain a thermoplastic compound or may contain a curable compound.

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

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

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

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

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

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

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

  From the viewpoint of enhancing the curability of the anisotropic conductive material, further improving the conduction reliability between the electrodes, and further enhancing the adhesive strength of the cured product, the anisotropic conductive material is an unsaturated double bond. And a curable compound having both a thermosetting functional group. Examples of the thermosetting functional group include an epoxy group, a thiirane group, and an 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 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, glycerine methacrylate acrylate, pentaerythritol tri (meth) acrylate, tri Examples include methylolpropane trimethacrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, polyester (meth) acrylate, and urethane (meth) acrylate.

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

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

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

  The anisotropic conductive material preferably contains a curable compound having an epoxy group or a 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 the thermosetting compound and the photocurable compound are used in combination, the mixing ratio of the photocurable compound and the thermosetting compound is appropriately determined according to the type of the photocurable compound and the thermosetting compound. Adjusted. 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.

(Thermal cation generator)
The anisotropic conductive material according to the present invention includes the above-described conductive particles and a binder resin. The anisotropic conductive material according to the present invention preferably further includes a thermal cation generator that releases an inorganic acid anion by heating or releases an organic acid anion containing a boron atom by heating.

  The thermal cation generator releases inorganic acid anions upon heating, or releases organic acid anions containing boron atoms upon heating. These thermal cation generators can remove the oxide film on the outer surface of the solder layer and the oxide film on the electrode surface by the inorganic acid anion or the organic acid anion released by heating.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

The thermal cation generator is preferably a sulfonium-based thermal cation generator. The component having the sulfonium cation moiety and the anion moiety of SbF ⁶⁻ , the anion moiety of PF ⁶⁻ , or the anion moiety represented by the above formula (2) acts as a thermal cation generator.

  The content of the thermal cation generator is not particularly limited. The content of the thermal cation generator is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, and still more preferably 5 parts by weight with respect to 100 parts by weight of the curable compound curable by heating. Part or more, particularly preferably 10 parts by weight or more, preferably 40 parts by weight or less, more preferably 30 parts by weight or less, still more preferably 20 parts by weight or less. When the content of the thermal cation generator is not less than the above lower limit and not more than the above upper limit, the anisotropic conductive material is sufficiently thermoset, and the conduction reliability in the connection structure is further enhanced. Furthermore, the oxide film on the outer surface of the solder layer and the oxide film on the electrode surface can be more effectively removed, and the conduction reliability in the connection structure is further enhanced.

  The blending ratio of the conductive particles and the thermal cation generator in the anisotropic conductive material is preferably 1: 1 to 20: 1 by weight, and preferably 2: 1 to 15: 1. More preferred is 5: 2 to 10: 1.

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

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

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

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

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

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

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

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

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

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

  The anisotropic conductive material may contain a different flux from the thermal cation generator. By using the flux, the oxide film formed on the electrode surface can be effectively removed. As a result, the conduction reliability in the connection structure is further increased. Note that the anisotropic conductive material does not necessarily contain a flux.

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

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

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

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

  In 100% by weight of the anisotropic conductive material, the content of the flux different from the thermal cation generator 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 above lower limit and not more than the upper limit, the oxide film formed on 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 thermal expansion coefficient of the cured product of the anisotropic conductive material can be suppressed. Specific examples of the filler include silica, aluminum nitride, alumina, glass, boron nitride, silicon nitride, silicone, carbon, graphite, graphene, and talc. As for a filler, only 1 type may be used and 2 or more types may be used together. When a filler having a high thermal conductivity is used, the main curing time is shortened.

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

(Other details of anisotropic conductive material and connection structure)
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.

  A connection structure can be obtained by connecting the connection target members using the anisotropic conductive material according to the present invention.

  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 the specific thermal cation generator, the oxide film on the surface of the copper electrode can be effectively removed, and the conduction reliability in the connection structure can be improved. Can be increased.

  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.

  The connection structure includes a first connection target member, a second connection target member, and a connection portion that electrically connects the first and second connection target members. The part is preferably formed of the anisotropic conductive material. It is preferable that the connection portion is formed by curing the anisotropic conductive material.

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

  A connection structure 51 shown in FIG. 3 includes a first connection target member 52, a second connection target member 53, and a connection portion that electrically connects the first and second connection target members 52 and 53. 54. The connection portion 54 is formed by curing an anisotropic conductive material including the conductive particles 1 and the binder resin. In FIG. 3, the conductive particles 1 are schematically shown for convenience of illustration.

  The first connection target member 52 has a plurality of first electrodes 52b on the upper surface 52a. The second connection target member 53 has a plurality of second electrodes 53b on the lower surface 53a. The first electrode 52 b and the second electrode 53 b are electrically connected by one or a plurality of conductive particles 1. Therefore, the first and second connection target members 52 and 53 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 target member and the second connection target member to obtain a laminate, and then the laminate is heated. And a method of applying pressure. By heating and pressing, the first and second solder layers 4 and 5 of the conductive particles 1 are melted, and the conductive particles 1 electrically connect the first and second electrodes 52b and 53b. The At this time, the conductive layer 3 is preferably brought into contact with the first and second electrodes 52b and 53b. Furthermore, it is preferable that the first solder layer 4 is in contact with the first and second electrodes 52b and 53b. When the binder resin contains a curable compound that can be cured by heating, the binder resin is cured, and the first and second connection target members 52 and 53 are connected by the cured binder resin. The pressure of the said pressurization is about 9.8 * 10 < ⁴ > -4.9 * 10 < ⁶ > Pa. The temperature of the said heating is about 120-220 degreeC.

FIG. 4 is an enlarged front sectional view of a connection portion between the conductive particle 1 and the first and second electrodes 52b and 53b in the connection structure 51 shown in FIG. As shown in FIG. 4, in the connection structure 51, after the first and second solder layers 4 and 5 of the conductive particles 1 are melted by heating and pressurizing the laminated body, the melted solder layer portion. X is in sufficient contact with the first and second electrodes 52b and 53b. That is, the conductive layer 3 and the first solder layer 4 are also the first and second electrodes 52b and 53b.
Can be contacted. Moreover, the connection resistance between electrodes can be made still lower by making the conductive layer 3 contact the 1st, 2nd electrodes 52b and 53b. The conductive layer is preferably in contact with the electrode, the first solder layer is preferably in contact with the electrode, and both the conductive layer and the first solder layer are more preferably in contact with the electrode.

  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. The anisotropic conductive material is preferably in the form of a paste and is applied to the upper surface of the connection target member in a paste 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 metal oxide include indium oxide doped with a trivalent metal element and zinc oxide doped with a trivalent metal element. Examples of the trivalent metal element include Sn, Al, and Ga.

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

  Hereinafter, the present invention will be specifically described with reference to Examples 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.

(Conductive particles)
Conductive particles 1: a 1 μm thick copper layer is laminated on the surface of the resin particles, and a 1 μm thick first solder layer (containing 0.1% by weight of oxygen atoms) is laminated on the surface of the copper layer. Conductive particles in which a second solder layer (containing 1.5% by weight of oxygen atoms) having a thickness of 50 nm is laminated on the surface of the first solder layer (produced as follows)

Production method of conductive particles 1:
Electroless copper plating is performed on divinylbenzene resin particles having an average particle diameter of 20 μm (“Micropearl SP-220” manufactured by Sekisui Chemical Co., Ltd.), and a base copper plating layer having a thickness of 1 μm is formed on the surface of the resin particles. Obtained. Thereafter, using a theta composer (manufactured by Tokuju Kogakusha Co., Ltd.), solder fine powder (42 wt% tin, 58 wt% bismuth, 0.1 wt% oxygen atom) The first solder layer having a thickness of 1 μm was formed on the surface of the copper layer. Next, using theta composer (manufactured by Tokuju Kogakusha Co., Ltd.), on the surface of the obtained first solder layer, fine solder powder (42 wt% tin, 58 wt% bismuth and 1.5 wt% oxygen atoms) And a second solder layer having a thickness of 50 nm was formed on the surface of the first solder layer.

  In this way, a 1 μm thick copper layer is laminated on the surface of the resin particles, and a 1 μm thick first solder layer (containing 0.1 wt% of oxygen atoms) is laminated on the surface of the copper layer. Thus, conductive particles were produced in which a second solder layer (containing 1.5% by weight of oxygen atoms) having a thickness of 50 nm was laminated on the surface of the first solder layer.

  Also, the following conductive particles 2 to 9 were produced by changing the content of oxygen atoms in the solder fine powder and the amount of solder fine powder used.

Conductive particle 2: a 1 μm thick copper layer is laminated on the surface of the resin particle, and a 1 μm thick first solder layer (containing 0.1% by weight of oxygen atoms) is laminated on the surface of the copper layer. Conductive particles in which a second solder layer (containing 1.5% by weight of oxygen atoms) having a thickness of 150 nm is laminated on the surface of the first solder layer. Conductive particles 3: on the surface of the resin particles A 1 μm thick copper layer is laminated on the surface of the copper layer, and a 1 μm thick first solder layer (containing 0.1 wt% of oxygen atoms) is laminated on the surface of the copper layer. Conductive particles in which a second solder layer (containing 1.5% by weight of oxygen atoms) having a thickness of 300 nm is laminated on the surface. Conductive particles 4: a copper layer having a thickness of 1 μm is laminated on the surface of the resin particles. A first solder layer having a thickness of 1 μm on the surface of the copper layer (containing 0.1% by weight of oxygen atoms) Conductive particles in which a second solder layer (containing 3 wt% of oxygen atoms) having a thickness of 50 nm is laminated on the surface of the first solder layer. Conductive particles 5: on the surface of the resin particles A 1 μm thick copper layer is laminated on the surface of the copper layer, and a 1 μm thick first solder layer (containing 0.1 wt% of oxygen atoms) is laminated on the surface of the copper layer. Conductive particles in which a second solder layer (containing 3% by weight of oxygen atoms) having a thickness of 150 nm is laminated on the surface. Conductive particles 6: A copper layer having a thickness of 1 μm is laminated on the surface of the resin particles. A first solder layer (containing 0.1% by weight of oxygen atoms) having a thickness of 1 μm is laminated on the surface of the copper layer, and a second solder layer (having a thickness of 300 nm is formed on the surface of the first solder layer. Conductive particles containing 3% by weight of oxygen atoms) Conductive particles 7: resin particles A copper layer having a thickness of 1 μm is laminated on the surface of the first layer, and a first solder layer having a thickness of 1 μm (containing 0.1% by weight of oxygen atoms) is laminated on the surface of the copper layer. Conductive particles in which a second solder layer (containing 5% by weight of oxygen atoms) having a thickness of 50 nm is laminated on the surface of the solder layer. Conductive particles 8: a copper layer having a thickness of 1 μm is laminated on the surface of the resin particles. A first solder layer having a thickness of 1 μm (containing 0.1% by weight of oxygen atoms) is laminated on the surface of the copper layer, and a second solder layer having a thickness of 150 nm is formed on the surface of the first solder layer. Conductive particles in which a solder layer (containing 5% by weight of oxygen atoms) is laminated Conductive particles 9: a copper layer having a thickness of 1 μm is laminated on the surface of the resin particles, and a thickness of 1 μm on the surface of the copper layer The first solder layer (containing 0.1 wt% of oxygen atoms) is laminated, and the first solder Conductive particles in which a second solder layer (containing 5% by weight of oxygen atoms) having a thickness of 300 nm is laminated on the surface of the layer. Conductive particles 10: A copper layer having a thickness of 1 μm is laminated on the surface of the resin particles. Conductive particles in which a single solder layer (containing 0.1% by weight of oxygen atoms) having a thickness of 1 μm is laminated on the surface of the copper layer (produced as follows)

Method for producing conductive particle 10:
Electroless copper plating is performed on divinylbenzene resin particles having an average particle diameter of 20 μm (“Micropearl SP-220” manufactured by Sekisui Chemical Co., Ltd.), and a base copper plating layer having a thickness of 1 μm is formed on the surface of the resin particles. Obtained. Thereafter, using a theta composer (manufactured by Tokuju Kogakusha Co., Ltd.), solder fine powder (42 wt% tin, 58 wt% bismuth, 0.1 wt% oxygen atom) The average particle diameter of 200 nm) is melted to a thickness of 1 on the surface of the copper layer.
A single solder layer of μm was formed.

  Also, the following conductive particles 11 were produced by changing the content of oxygen atoms in the solder fine powder.

  Conductive particles 11: a 1 μm thick copper layer is laminated on the surface of the resin particles, and a 1 μm thick single layer solder layer (containing 5% by weight of oxygen atoms) is laminated on the surface of the copper layer. Conductive particles

(Binder resin)
Thermosetting compound 1 (epoxy resin, “EXA-4850-150” manufactured by DIC)
Thermosetting compound 2 (epoxy resin, “JER-828” manufactured by Mitsubishi Chemical Corporation)

(Other ingredients)
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)

(Examples 1 to 12 and Comparative Examples 1 and 2)
By blending the blending components shown in Table 1 below in the blending amounts shown in Table 1 below and stirring at 2000 rpm for 5 minutes using a planetary stirrer, an anisotropic conductive material that is an anisotropic conductive paste is obtained. Obtained.

(Evaluation)
(1) Storage stability The obtained anisotropic conductive material was allowed to stand at 25 ° C. for 5 days. Thereafter, the viscosity before standing and the viscosity after standing were measured, and the storage stability was evaluated by determining the rate of increase in viscosity. Storage stability was determined according to the following criteria.

[Criteria for storage stability]
○○: Viscosity increase rate 1.2 times or less ×: Viscosity increase rate 1.2 times

(2) Production of Connection Structure An FR-4 substrate having a gold electrode pattern with an L / S of 200 μm / 200 μm formed on the upper surface was prepared. In addition, a polyimide substrate (flexible substrate) having a gold electrode pattern with L / S of 200 μm / 200 μm formed on the lower surface was prepared.

  After stirring the obtained anisotropic conductive material on the upper surface of the FR-4 substrate, it is applied so that the thickness is twice the average particle diameter of the conductive particles contained in the anisotropic conductive material. And an anisotropic conductive material layer was formed.

  Next, a polyimide substrate (flexible substrate) was laminated on the upper surface of the anisotropic conductive material layer so that the electrodes face each other. Then, while adjusting the temperature of the head so that the temperature of the anisotropic conductive material layer is 185 ° C., a pressure heating head is placed on the upper surface of the semiconductor chip and a pressure of 2.0 MPa is applied to apply the anisotropic conductive material. The material layer was cured at 185 ° C. to obtain a connection structure.

(3) Conductivity test between upper and lower electrodes The connection resistance between the upper and lower electrodes of the connection structure obtained in the above (2) 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 less than 8Ω ○: Average value of connection resistance is 8Ω or more and less than 10Ω Δ: Average value of connection resistance is 10Ω or more and less than 20Ω ×: Average value of connection resistance is 20Ω or more

  The results are shown in Table 1 below.

  In the connection structure using the anisotropic conductive material obtained in Examples 1 to 12, the first and second solder layers are solidified after being melted, and the conductive layer and the first solder layer are solidified. And the electrode were in contact.

DESCRIPTION OF SYMBOLS 1 ... Conductive particle 2 ... Base particle 2a ... Surface 3 ... Conductive layer 3a ... Surface 4 ... 1st solder layer 4a ... Outer surface 5 ... 2nd solder layer 11 ... Conductive particle 12 ... Conductive layer 12a ... Surface 13 ... first solder layer 13a ... outer surface 14 ... second solder layer 21 ... inner conductive layer 22 ... outer conductive layer 51 ... connection structure 52 ... first connection target member 52a ... upper surface 52b ... 1st electrode 53 ... 2nd connection object member 53a ... Bottom surface 53b ... 2nd electrode 54 ... Connection part X ... Molten solder layer part

Claims (16)

Containing conductive particles and a binder resin,
The conductive particles are substrate particles, a first solder layer disposed on the surface of the substrate particles, and a second solder layer laminated on the outer surface of the first solder layer. With
An anisotropic conductive material, wherein the content of oxygen atoms in 100% by weight of the second solder layer is greater than the content of oxygen atoms in 100% by weight of the first solder layer.   2. The oxygen atom content in 100 wt% of the second solder layer is 0.5 wt% or more higher than the oxygen atom content in 100 wt% of the first solder layer. Anisotropic conductive material. The oxygen atom content in 100% by weight of the second solder layer is 1.5% by weight or more and 5.0% by weight or less,
The anisotropic conductive material according to claim 1 or 2, wherein the content of oxygen atoms in 100% by weight of the first solder layer is 0.5% by weight or less.   The anisotropic conductive material according to any one of claims 1 to 3, further comprising a thermal cation generator that releases inorganic acid anions by heating or releases organic acid anions containing boron atoms by heating.   The anisotropic conductive material of any one of Claims 1-4 in which the said binder resin contains an epoxy compound. The conductive particles further comprising a conductive layer disposed between the base particle and the first solder layer;
The said conductive layer is laminated | stacked on the surface of the said base particle, The 1st solder layer is laminated | stacked on the outer surface of the said conductive layer, The any one of Claims 1-5. Anisotropic conductive material.   The anisotropic conductive material according to claim 1, wherein the substrate particles are resin particles.   The anisotropic conductive material according to claim 1, wherein the anisotropic conductive material is a paste-like anisotropic conductive paste.   The anisotropic conductive material of any one of Claims 1-8 which is an anisotropic conductive material used in order to connect the connection object member which has a copper electrode. Comprising a mixing step of mixing conductive particles and a binder resin;
As the conductive particles, base particles, a first solder layer disposed on the surface of the base particles, and a second solder layer laminated on the outer surface of the first solder layer, Anisotropy using conductive particles in which the content of oxygen atoms in 100% by weight of the second solder layer is greater than the content of oxygen atoms in 100% by weight of the first solder layer A method for producing a conductive material. When the first and second solder layers are formed before the mixing step, the content of oxygen atoms in 100% by weight of the second solder layer is 100% by weight of the first solder layer. Whether the first and second solder layers are formed so as to be greater than the oxygen atom content of the conductive particles to obtain the conductive particles comprising the base material particles and the first and second solder layers Or, using the conductive particles before oxidation comprising the substrate particles and the first and second solder layers, the oxidation of the second solder layer of the conductive particles before oxidation proceeds, The content of oxygen atoms in 100% by weight of the second solder layer is made larger than the content of oxygen atoms in 100% by weight of the first solder layer, so that the base particles and the first and first The anisotropic conductive material according to claim 10, further comprising a step of obtaining the conductive particles including two solder layers. Method of manufacturing a fee.   In the mixing step, the conductive particles, the binder resin, and a thermal cation generator that releases inorganic acid anions by heating or releases organic acid anions containing boron atoms by heating are mixed. A method for producing an anisotropic conductive material according to 10 or 11. A first connection target member;
A second connection target member;
A connecting portion electrically connecting the first and second connection target members;
The connection structure in which the said connection part is formed with the anisotropic conductive material of any one of Claims 1-9. A first connection target member;
A second connection target member;
A connecting portion electrically connecting the first and second connection target members;
A connection structure in which the connecting portion is formed of an anisotropic conductive material obtained by the method for manufacturing an anisotropic conductive material according to any one of claims 10 to 12. The first connection object member has a first electrode on an upper surface;
The second connection target member has a second electrode on the lower surface;
The connection structure according to claim 13 or 14, wherein the first electrode and the second electrode are electrically connected by the conductive particles.   The connection structure according to claim 15, wherein at least one of the first electrode and the second electrode is a copper electrode.

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