Method for sorting electrically conductive particles, circuit connecting material, connecting structure and method for manufacturing the same, and electrically conductive particles

Abstract

The present application relates to a sorting method of conductive particles, a circuit connecting material, a connecting structure and a manufacturing method thereof, and a conductive particle. The sorting method of the conductive particles includes a process of determining whether a metal constituting an outermost layer of the conductive particle satisfies a first condition, and a process of determining whether the conductive particle satisfies a second condition, and the conductive particle satisfying both the first condition and the second condition is determined as good, the first condition: the electrical conductivity at 20°C is less than or equal to 40 x 10 6 S / m, and the second condition: the volume specific resistance when a load of 2 kN is applied is less than or equal to 15 mΩcm.

Description

[0001] This application is a divisional application of the Chinese Patent Application No. 201880021662.3, filed on March 28, 2018, entitled "Method for sorting electrically conductive particles, circuit connecting material, connecting structure and method for manufacturing the same, and electrically conductive particles". TECHNICAL FIELD

[0002] The present disclosure relates to a method for sorting electrically conductive particles, a circuit connecting material, a connecting structure and a method for manufacturing the same, and electrically conductive particles. BACKGROUND

[0003] An IC for driving is mounted on a glass panel for liquid crystal and OLED (Organic Light-Emitting Diode) display. The manner can be roughly divided into two types of COG (Chip-on-Glass) mounting and COF (Chip-on-Flex) mounting. In the COG mounting, an anisotropic conductive adhesive containing electrically conductive particles is used to directly bond the IC for driving on the glass panel. On the other hand, in the COF mounting, the IC for driving is bonded to a flexible tape having a metal wiring, and they are bonded to the glass panel using an anisotropic conductive adhesive containing electrically conductive particles. The anisotropy here means that it is conductive in the direction of pressure, and remains insulating in the direction other than the pressure direction. The anisotropic conductive adhesive containing electrically conductive particles can be formed in advance in a film shape, and such a film is called an anisotropic conductive film.

[0004] So far, the wiring on the glass panel has been mainly ITO (Indium Tin Oxide) wiring, but it is being replaced by IZO (Indium Zinc Oxide) for the purpose of improving productivity or smoothness. Further, in recent years, an electrode formed by laminating multiple layers of Cu, Al, Ti, etc. on a glass panel, and a composite multilayer electrode having ITO or IZO further formed on the top surface, etc. have been developed. For such an electrode having high flatness and using a high-hardness material such as Ti, it is necessary to obtain a stable connection resistance.

[0005] Patent Document 1 discloses a method for manufacturing electrically conductive particles containing a base material particle and an electrically conductive film formed on the surface thereof, and the electrically conductive film has a protrusion protruding on the surface. According to the document, the electrically conductive reliability of the electrically conductive particles having the protrusion of the electrically conductive film is excellent.

[0006] Patent Document 2 discloses a conductive particle including a base material particle and a nickel-boron conductive layer provided on the surface thereof. According to this document, since the nickel-boron conductive layer has moderate hardness, when connecting to a member between electrodes, the oxidation film on the surface of the electrode and the conductive particle can be sufficiently removed, and thus the connection resistance can be reduced.

[0007] Patent Document 3 discloses a conductive particle having a resin particle, an electrolytic-free metal plating layer covering the surface thereof, and a metal sputtering layer other than Au forming the outermost layer. According to this document, by covering the surface of the resin particle with the electrolytic-free metal plating layer, the adhesion to the surface of the resin particle can be improved, and by providing the outermost layer as the metal sputtering layer, good connection reliability can be obtained.

[0008] Prior Art Documents

[0009] Patent Documents

[0010] Patent Document 1: Japanese Patent No. 4563110

[0011] Patent Document 2: Japanese Patent Application Laid-Open (JP-A) No. 2011-243455

[0012] Patent Document 3: Japanese Patent Application Laid-Open (JP-A) No. 2012-164454 SUMMARY

[0013] PROBLEMS TO BE SOLVED BY THE INVENTION

[0014] Further, conventionally, with respect to the conductive particle used in the manufacturing process of a display or the anisotropic conductive film containing the same, a panel manufacturer selects a material of a raw material suitable for the surface of an electrode from among a plurality of kinds and uses the same. For example, a circuit having titanium on the surface used in an organic EL display or the like is non-conductive because titanium oxide is formed on the surface, and thus a conductive particle having a hard plating layer compared to the conventional one can be used. Thereby, at the time of press bonding, the conductive particle penetrates the non-conductive film on the surface and contacts the conductive portion inside the electrode, and thus low resistance is achieved. However, if such a conductive particle improved by a physical method is applied to an electrode of, for example, an ITO film, there is a problem that the conductive particle before the improvement sometimes shows low resistance, and the like, and lacks versatility.

[0015] Recently, along with the rapid commercialization of display-related products, competition among panel manufacturers has become intense. Among the panel manufacturers, there are manufacturers who strive to achieve the unification of the kinds of anisotropic conductive films in order to improve cost competitiveness. However, the reality is that the unification of the kinds of anisotropic conductive films is difficult for the following reasons.

[0016] First, electrode circuits of liquid crystal displays and organic EL displays are not the same. For example, oxide-based transparent conductive films (ITO, IZO, IGZO, IGO, ZnO, etc.) are mainly used in liquid crystal displays. On the other hand, electrode materials mainly composed of metals such as titanium, chromium, aluminum, and tantalum are mainly used in organic EL displays. In addition, there are cases where the surface of the electrode is coated with an organic material such as an acrylic resin, an inorganic material such as SiNx or SiOx for the purpose of protecting the electrode portion or improving reliability. Further, as electrode circuits other than display substrates, FPC (Flexible Printed Circuit), IC (Integrated Circuit), and the like can be cited, and various metals such as gold, copper, and nickel are used in these electrodes.

[0017] The present disclosure was completed in view of the above-described actual situations, and aims to provide a method of sorting conductive particles having sufficiently high versatility with respect to circuit electrodes of circuit members to be connected. In addition, the present disclosure aims to provide a conductive particle, a circuit connecting material using the same, a connection structure, and a manufacturing method thereof.

[0018] Method of solving the problem

[0019] The present disclosure relates to a sorting method of a conductive particle. The sorting method includes a step of determining whether a metal constituting an outermost layer of the conductive particle satisfies a first condition described below, and a step of determining whether the conductive particle satisfies a second condition described below, and the conductive particle satisfying both the first condition and the second condition is determined to be good.

[0020] First condition: electrical conductivity at 20°C is less than or equal to 40 x 10 6 S / m

[0021] Second condition: volume-specific resistance when a load of 2 kN is applied is less than or equal to 15 mΩcm

[0022] By using the conductive particles satisfying both the first condition and the second condition, for various surface compositions of circuit electrodes (transparent conductive films of oxide systems such as ITO and metal-made electrodes such as Ti and the like), the resistance of the contact interface of the conductive particles and the electrode surface can be reduced, and a good connection resistance can be obtained. The present inventors have found that, in particular, the second condition is useful in terms of achieving a good connection resistance and high sorting versatility of the conductive particles. The so-called 2 kN load is presumed to be a state in which the conductive particles are substantially not flattened. Therefore, it is considered that, compared to the case of a large load, the resistance value of the surface of the conductive particles can be detected with high sensitivity. In addition, in the actual connection portion, due to the particle size deviation of the conductive particles or the fine irregularities of the electrode surface, conductive particles having different flattening rates are mixed between the pair of electrodes facing each other. That is, among these conductive particles, particles that are substantially not flattened are also included. As described above, the conductive particles sorted by the method related to the present disclosure contribute greatly to the low resistance of the connection portion even if they are slightly flattened, and a good connection resistance can be obtained as a whole. In contrast, the conductive particles that do not satisfy either of the first condition and the second condition contribute less to the low resistance of the connection portion when they are slightly flattened. Note that, in the present specification, "facing" means that a pair of members face each other.

[0023] Effects of Invention

[0024] According to the present disclosure, a method of sorting conductive particles having sufficiently high sorting versatility for circuit electrodes of circuit members to be connected can be provided. In addition, according to the present disclosure, a conductive particle, a circuit connection material using the same, and a connection structure and a manufacturing method thereof can be provided. BRIEF DESCRIPTION OF DRAWINGS

[0025] [ Figure 1 ] Figure 1 (a) of FIG. 1 is a schematic cross-sectional view that enlargedly shows a connection portion of a connection structure manufactured using conductive particles sorted by the method related to the present disclosure, Figure 1 (b) of FIG. 1 is a schematic cross-sectional view that enlargedly shows a connection portion of a connection structure manufactured using conductive particles that do not satisfy either of the first condition and the second condition.

[0026] [ Figure 2 ] Figure 2 is a graph showing an example of a measurement result of volume-specific resistance.

[0027] [ Figure 3 ] Figure 3 (a) to (c) of FIG. 2 are cross-sectional views that schematically show an example of a manufacturing method of a connection structure. DETAILED DESCRIPTION

[0028] The embodiments of this disclosure will now be described in detail. However, the present invention is not limited to these embodiments.

[0029] <Sorting Methods for Conductive Particles>

[0030] The method for sorting conductive particles according to this embodiment includes: a step of determining whether the metal constituting the outermost layer of the conductive particle satisfies the following first condition, and a step of determining whether the conductive particle satisfies the following second condition, and determining conductive particles that satisfy both the first condition and the second condition as good.

[0031] First condition: Conductivity at 20℃ is less than or equal to 40 × 10⁻⁶ 6 S / m

[0032] Second condition: The volume resistivity under a 2kN load is less than or equal to 15mΩcm

[0033] By employing conductive particles that satisfy both the first and second conditions, the resistance at the contact interface between the conductive particles and the electrode surface can be reduced for circuit electrodes with various surface compositions (such as transparent conductive films made of oxides like ITO and metal electrodes like Ti), thereby achieving good connection resistance.

[0034] Figure 1 (a) is a schematic cross-sectional view showing an enlarged view of the connection portion of the connection structure manufactured using conductive particles sorted by the method involved in this embodiment. Figure 1 The conductive particles 1 (conductive particles 1a and 1b) shown in (a) satisfy both the first and second conditions. Figure 1 (b) is a schematic cross-sectional view showing an enlarged view of the connection portion of a connection structure manufactured using conductive particles 2 (2a, 2b) that do not satisfy either the first or second condition. In these figures, the thickness of the arrows indicates the ease of current flow.

[0035] like Figure 1 As shown in (a), at the connection portion of the connecting structure 10, due to the particle size deviation of the conductive particles 1, conductive particles 1 with different flatness ratios are mixed between the circuit electrodes 3a and 4a of each of the opposing pair of circuit components 3 and 4. Figure 1 As schematically shown in (a), of the three conductive particles 1a, 1b, and 1a, two conductive particles 1a and 1a are essentially not flattened. Even when slightly flattened, conductive particles 1 (conductive particles 1a and 1b) contribute significantly to the reduction of resistance at the connection, thus achieving good overall connection resistance. In contrast, Figure 1The electrically conductive particles 2 (2a, 2b) of (b) contribute less to the low resistance of the connection portion when slightly flattened. Note that, in this case, a mixture of electrically conductive particles having different flatness ratios due to a particle size deviation of the electrically conductive particles is illustrated, but even if the particle size of the electrically conductive particles is sufficiently uniform, the degree of flatness of the electrically conductive particles can vary due to the surface irregularities of the circuit electrodes 3a, 4a.

[0036] The electrical conductivity of the outermost layer involved in the first condition can be measured, for example, using an electrical conductivity meter (device name: SIGMATEST, manufactured by Foerster Corporation, Japan). However, the electrically conductive particles are generally very small, and it is difficult to measure them using this device. Therefore, instead of actually measuring the electrical conductivity using such a device, the elements constituting the outermost layer can be analyzed, and the electrical conductivity can be determined based on the type of the elements. From the viewpoint of further reducing the connection resistance of the connection portion of the connection structure, the first condition (electrical conductivity of the metal layer at 20°C) can be set to 1 x 10 6 ~ 40 x 10 6 S / m, or to 5 x 10 6 ~ 40 x 10 6 S / m.

[0037] The bulk specific resistance involved in the second condition can be measured, for example, using a powder resistance measuring system (device name: PD51, manufactured by Mitsubishi Chemical Analysis Technology Co., Ltd.). Specifically, 2.5 g of electrically conductive particles are placed in a dedicated sample cell of the above device, and the bulk specific resistance of the electrically conductive particles under a load of 2 kN is measured using the above device. Note that the amount of electrically conductive particles placed can be any amount that fills the bottom surface of the dedicated sample cell, and can be 0.5 g or more. In addition, the measurement load can be arbitrarily changed.

[0038] Figure 2 is a graph showing an example of the measurement results of the bulk specific resistance. Figure 2 The results are the results measured every 2 kN from 2 kN to 20 kN. In the present embodiment, the bulk specific resistance at 2 kN is used as an index. From the viewpoint of further reducing the connection resistance of the connection portion of the connection structure and obtaining a circuit connection material with higher versatility, the second condition (bulk specific resistance under a load of 2 kN) can be set to be less than or equal to 10 mΩcm, or to be less than or equal to 7.5 mΩcm or less than or equal to 5 mΩcm.

[0039] <CONDUCTIVE PARTICLES>

[0040] As the conductive particles, there is no particular limitation as long as they have compression characteristics, and for example, a core-shell particle having a core particle containing a resin material and a metal layer covering the core particle can be exemplified. The metal layer need not cover the entire surface of the core particle, and can be in a state where the surface of the core particle is partially covered with the metal layer. In addition, the metal layer can be a single layer structure or a multilayer structure.

[0041] The particle diameter of the conductive particles is generally smaller than the minimum value of the electrode interval of the circuit member to be connected. In the case where there is a deviation in the height of the electrodes to be connected, the average particle diameter of the conductive particles is preferably greater than the deviation in the height. From such a viewpoint, the average particle diameter of the conductive particles is preferably 1 to 50 μm, more preferably 1 to 20 μm, further preferably 2 to 10 μm, and particularly preferably 2 to 6 μm. Note that the "average particle diameter" in the present specification means a value obtained by observation with a differential scanning electron microscope. That is, one particle is arbitrarily selected, and the maximum diameter and the minimum diameter thereof are measured by observation with a differential scanning electron microscope. The square root of the product of the maximum diameter and the minimum diameter is taken as the particle diameter of the particle. In this method, the particle diameters of 50 arbitrarily selected particles are measured, and the average value thereof is taken to obtain the average particle diameter of the particles.

[0042] As described above, the conductive particles to be sorted have a volume-specific electrical resistance of 15 mΩcm or less at the time of application of a load of 2 kN. From the viewpoint of further reducing the connection resistance of the connection portion of the connection structure and obtaining a circuit connection material having higher versatility, the above volume-specific electrical resistance is preferably 0.1 to 10 mΩcm, more preferably 0.1 to 7.5 mΩcm, and further preferably 0.1 to 5 mΩcm.

[0043] The compression elastic modulus (20% K value) of the conductive particles at the time of 20% compression displacement at 25°C is preferably 0.5 to 15 GPa, and more preferably 1.0 to 10 GPa. The compression hardness K value is an index of the softness of the conductive particles, and by taking the 20% K value in the above range, the conductive particles are moderately flattened between the electrodes when the electrodes facing each other are connected to each other, and thus the contact area of the electrodes and the particles is easily ensured, and thus there is a tendency to further improve the connection reliability.

[0044] The 20% K value of the conductive particles can be obtained using a Fischerscope H100C (manufactured by Fischer Instruments) by the following method. One conductive particle dispersed on a glass slide is compressed at a speed of 0.33 mN / sec. Thereby, a stress-strain curve is obtained, and the 20% K value is obtained from the curve. Specifically, when a load F (N), a displacement S (mm), a radius R (mm) of the particle, an elastic modulus E (Pa), and a Poisson's ratio σ are set, the compression formula F = (2 1 / 2 / 3) x (S3 / 2 ) x (E x R 1 / 2 ) / (1 - σ 2 ), and is found by the following formula K = E / (1 - σ 2 ) = (3 / 2 1 / 2 ) x F x (S -3 / 2 ) x (R -1 / 2 ). Further, if the deformation rate X (%) and the diameter D (μm) of the ball are set, the K value at an arbitrary deformation rate can be found by the following formula K = 3000F / (D 2 x X 3 / 2 ) x 10 6 . The deformation rate X is calculated by the following formula X = (S / D) x 100. The maximum test load in the compression test is set to, for example, 50 mN.

[0045] (nuclear particle)

[0046] As described above, the conductive particle in the present embodiment is a core-shell type particle, and includes a nuclear particle. By the conductive particle having a nuclear particle, the physical property design range of the conductive particle itself is greatly expanded, and in addition, the size uniformity of the conductive particle is improved compared to a metal powder or the like, so in the connection of various members to each other, the conductive particle is easily optimized.

[0047] As a specific example of the nuclear particle, various plastic particles can be listed. The plastic particle can be listed, for example, a particle formed of at least one resin selected from the group consisting of: polymethyl methacrylate, polymethyl acrylate, and the like acryl-based resins; polyethylene, polypropylene, polyisobutylene, polybutadiene, and the like polyolefin-based resins; polystyrene-based resins, polyester-based resins, polyurethane-based resins, polyamide-based resins, epoxy-based resins, polyvinyl butyral-based resins, rosin-based resins, terpene-based resins, phenol-based resins, guanamine-based resins, melamine-based resins, oxazoline-based resins, carbodiimide-based resins, silicone-based resins, and the like. Note that, as the plastic particle, these resins can also be compounded with inorganic matter such as silica.

[0048] As the plastic particle, from the viewpoint of the easiness of control of the compression recovery rate and the compression hardness K value, a plastic particle including a resin obtained by polymerizing one polymerizable monomer having an ethylenic unsaturated group, or a plastic particle including a resin obtained by copolymerizing two or more polymerizable monomers having an ethylenic unsaturated group can be used. In the case where a resin is obtained by copolymerizing two or more polymerizable monomers having an ethylenic unsaturated group, by using a non-crosslinking monomer and a crosslinking monomer in combination, and suitably adjusting the copolymerization ratio and the kind thereof, the compression recovery rate and the compression hardness K value of the plastic particle can be easily controlled. As the above non-crosslinking monomer and the above crosslinking monomer, for example, the monomers described in Japanese Patent Application Publication No. 2004-165019 can be used.

[0049] The average particle diameter of the plastic particles is preferably 1 to 50 μm. Note that the average particle diameter of the plastic particles is more preferably 1 to 20 μm from the viewpoint of high-density mounting. Further, in the case where the unevenness on the surface of the electrode has a variation, the average particle diameter of the plastic particles is further preferably 2 to 10 μm from the viewpoint of more stably maintaining the connected state.

[0050] (Metal layer)

[0051] In the present embodiment, the outermost layer of the conductive particles is composed of a metal layer of a metal having an electrical conductivity of less than or equal to 40 x 10 6 S / m at 20°C. By adopting such a configuration, good connection reliability can be obtained. Note that the outermost layer here refers to a range of 50 nm or less from the surface of the metal layer. The metal constituting the outermost layer has an electrical conductivity of less than or equal to 40 x 10 6 S / m at 20°C, and preferably 1 x 10 6 ~ 40 x 10 6 S / m, and more preferably 5 x 10 6 ~ 20 x 10 6 S / m.

[0052] The metal layer can be composed of a single metal or an alloy. As the metal having an electrical conductivity of less than or equal to 40 x 10 6 S / m, Al, Ti, Cr, Fe, Co, Ni, Zn, Zr, Mo, Pd, In, Sn, W, Pt, and the like can be given. The metal layer is preferably formed of at least one metal selected from the group consisting of Ni, Ni / Au (a mode in which an Au layer is provided on a Ni layer. The same applies hereinafter), Ni / Pd, Ni / W, Cu, and NiB, for example. The metal layer can be formed by a general method such as plating, vapor deposition, sputtering, or the like, and can be a thin film. Note that in the case where the metal layer is formed on the plastic particles by plating, the metal layer preferably contains Ni, Pd, or W from the viewpoint of platability with respect to the plastic. Further, the metal layer preferably contains Ni from the viewpoint of resin exclusion between the electrode and the particles at the time of press contact, which leads to a lower resistance. Ni has the following advantages: not only is the resin exclusion property at the time of press contact excellent, but also platability and corrosion resistance are excellent as compared with Au, Cu, and Ag having a high electrical conductivity, and the stability of supply and the price are also excellent.

[0053] The thickness of the metal layer is preferably 10 to 1000 nm, more preferably 20 to 500 nm, and further preferably 50 to 250 nm from the viewpoint of achieving a balance between the conduction property and the price.

[0054] From the viewpoint of improving the insulating properties between adjacent electrodes, the conductive particles can also have an attached layer that is formed by attaching a layer of an insulating material (for example, an organic film) or insulating fine particles (for example, organic fine particles or inorganic fine particles) to the outer side of the metal layer. The thickness of the attached layer is preferably in the range of 50 to 1000 nm. Note that the attached layer is preferably formed for the conductive particles that have been confirmed to satisfy the first condition and the second condition. The thickness of the metal layer and the attached layer can be measured using, for example, a scanning electron microscope (SEM), a transmission electron microscope (TEM), an optical microscope, or the like. Further, the metal layer can also have protrusions formed on the surface. By having protrusions in the metal layer, further low resistance can be achieved due to the following effects: the resin exclusion at the time of pressure bonding becomes effective, the number of contact points with the electrodes increases, the inside of the electrode and the conductive particles can further come into contact, and the like.

[0055] < Circuit connecting material >

[0056] The circuit connecting material according to the present embodiment is used to bond circuit members to each other and electrically connect circuit electrodes (for example, connection terminals) possessed by each of the circuit members to each other. The circuit connecting material contains an adhesive component that is cured by light or heat, and conductive particles dispersed in the adhesive component, the conductive particles satisfying both the first condition and the second condition.

[0057] The circuit connecting material can be prepared by dispersing the conductive particles in the adhesive component. As the circuit connecting material, a paste-like adhesive composition can be used directly, or an anisotropic conductive film obtained by molding the same into a film shape can be used. Regarding the blending amount of the conductive particles, from the viewpoint of balancing the electrical conductivity between facing electrodes and the insulating properties between adjacent electrodes, when the total volume of the circuit connecting material is taken as 100 parts by volume, it is preferably in the range of 0.1 to 30 parts by volume, more preferably in the range of 0.5 to 15 parts by volume, and further preferably in the range of 1 to 7.5 parts by volume.

[0058] Regarding the blending amount of the adhesive component, from the viewpoint of easily maintaining the gap between electrodes at the time of circuit connection and after the connection, and easily ensuring the strength and elastic modulus required to have excellent connection reliability, when the total mass of the circuit connecting material is taken as 100 parts by mass, it is preferably in the range of 10 to 90 parts by mass, more preferably in the range of 20 to 80 parts by mass, and further preferably in the range of 30 to 70 parts by mass.

[0059] As the adhesive component, there is no particular limitation, and for example, a composition containing an epoxy resin and a latent curing agent for the epoxy resin (hereinafter referred to as "first composition"), a composition containing a radically polymerizable substance and a curing agent that generates a free radical by heating (hereinafter referred to as "second composition"), or a mixed composition of the first composition and the second composition is preferable.

[0060] As the epoxy resin contained in the first composition, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, bisphenol F novolac type epoxy resin, alicyclic epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, hydantoin type epoxy resin, isocyanurate type epoxy resin, aliphatic chain type epoxy resin, and the like can be exemplified. These epoxy resins can be halogenated or hydrogenated. Two or more of these epoxy resins can also be used in combination.

[0061] As the latent curing agent contained in the first composition, any curing agent that can cure the epoxy resin can be used, and as such a latent curing agent, anionic polymerization catalyst type curing agent, cationic polymerization catalyst type curing agent, polyaddition type curing agent, and the like can be exemplified. These can be used alone or as a mixture of two or more. Among these, from the viewpoint of excellent rapid curing properties and not needing to consider the chemical equivalent, an anionic or cationic polymerization catalyst type curing agent is preferred.

[0062] As the anionic or cationic polymerization catalyst type curing agent, an imidazole-based curing agent, a hydrazide-based curing agent, a boron trifluoride-amine complex, a sulfonium salt, an amine imide, a diaminomaleonitrile, a melamine and its derivatives, a salt of a polyamine, dicyandiamide, and the like can be exemplified, and modified products thereof can also be used. As the polyaddition type curing agent, a polyamine, a polythiol, a polyphenol, an acid anhydride, and the like can be exemplified.

[0063] In the case where a tertiary amine, an imidazole, or the like is used as the anionic polymerization catalyst type curing agent, the epoxy resin is cured by heating at a medium temperature of 160°C to 200°C for a period of several tens of seconds to several hours. Thus, the service life (use period) can be made longer. As the cationic polymerization catalyst type curing agent, for example, a photosensitive curing agent that cures the epoxy resin by irradiation of energy rays is preferred. As the photosensitive curing agent, a salt (aromatic diazonium salt, aromatic sulfonium salt, or the like) is preferred. salt (aromatic diazonium salt, aromatic sulfonium salt, or the like) is preferred. In addition, as a substance that activates by heating in addition to irradiation of energy rays to cure the epoxy resin, an aliphatic sulfonium salt or the like is preferred. Such a curing agent has the characteristic of rapid curing, and thus is preferred.

[0064] A substance in which the latent curing agent is coated and microencapsulated using a high molecular substance such as a polyurethane-based or polyester-based substance, a metal thin film such as nickel or copper, an inorganic substance such as calcium silicate, or the like is preferred because the service life can be extended. The amount of the latent curing agent contained in the first composition is preferably 20 to 80 parts by mass, and more preferably 30 to 70 parts by mass, relative to 100 parts by mass of the total of the epoxy resin and the film-forming material that is compounded as necessary.

[0065] The radical polymerizable substance contained in the second composition is a substance having a functional group that polymerizes by radicals. As such a radical polymerizable substance, mention can be made of: acrylate (also including the corresponding methacrylate. The same applies hereafter) compounds, acryloyloxy (also including the corresponding methacryloyloxy. The same applies hereafter) compounds, maleimide compounds, citraconimide resins, nadimide resins, and the like. The radical polymerizable substance can be used in the state of a monomer or an oligomer, or a monomer and an oligomer can be used in combination. As specific examples of the above-mentioned acrylate compounds, mention can be made of: methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, 2-hydroxy-l,3-diacryloyloxypropane, 2,2-bis[4-(acryloyloxymethoxy)phenyl]propane, 2,2-bis[4-(acryloyloxy polyethoxy)phenyl]propane, dicyclopentenyl acrylate, tricyclodecanyl acrylate, tris(acryloyloxyethyl) isocyanurate, urethane acrylate, and the like. These can be used alone or in combination of two or more. In addition, a polymerization inhibitor such as hydroquinone, hydroquinone methyl ether, and the like can be appropriately used as needed. In addition, from the viewpoint of improving heat resistance, it is preferable that the acrylate compound have at least one substituent selected from the group consisting of dicyclopentenyl, tricyclodecanyl, and triazine ring. A radical polymerizable substance other than the above-mentioned acrylate compounds can be appropriately used, for example, the compounds described in International Publication No. 2009 / 063827. These can be used alone or in combination of two or more.

[0066] In addition, it is preferable to use, in combination with the above-mentioned radical polymerizable substance, a radical polymerizable substance having a phosphate structure represented by the following formula (I). In this case, the adhesion strength to the surface of inorganic substances such as metals is improved, and thus it is suitable for the adhesion of circuit electrodes to each other.

[0067] [Chemical Formula 1]

[0068]

[0069] [In the formula, n represents an integer of 1 to 3.]

[0070] The radical polymerizable substance having a phosphate structure can be obtained by reacting phosphorous acid with 2-hydroxyethyl (meth)acrylate. As the radical polymerizable substance having a phosphate structure, specifically, there are monophosphorous acid mono(2-methacryloyloxyethyl) ester, diphosphorous acid di(2-methacryloyloxyethyl) ester, and the like. These can be used alone or in combination of two or more.

[0071] The content of the radical polymerizable substance having a phosphate structure represented by the above formula (I) is preferably 0.01 to 50 parts by mass, more preferably 0.5 to 5 parts by mass, relative to 100 parts by mass of the total of the radical polymerizable substance and the film-forming material as needed.

[0072] The radical polymerizable substance can also be used in combination with an allyl acrylate. In this case, the content of the allyl acrylate is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, relative to 100 parts by mass of the total of the radical polymerizable substance and the film-forming material as needed.

[0073] The curing agent contained in the second composition which generates a free radical by heating is a curing agent which is decomposed by heating and generates a free radical. As such a curing agent, peroxide, azo-based compounds, and the like can be exemplified. Such a curing agent can be appropriately selected depending on the target bonding temperature, bonding time, shelf life, and the like. From the viewpoint of high reactivity and improvement of the shelf life, an organic peroxide having a temperature at which the half-life is 10 hours of 40°C or higher and a temperature at which the half-life is 1 minute of 180°C or lower is preferred, and an organic peroxide having a temperature at which the half-life is 10 hours of 60°C or higher and a temperature at which the half-life is 1 minute of 170°C or lower is more preferred.

[0074] The content of the above curing agent is preferably 2 to 10 parts by mass, more preferably 4 to 8 parts by mass, relative to 100 parts by mass of the total of the radical polymerizable substance and the film-forming material as needed, in the case where the bonding time is set to be 25 seconds or less. Thereby, a sufficient reaction rate can be obtained. Note that the content of the curing agent when the bonding time is not limited is preferably 0.05 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, relative to 100 parts by mass of the total of the radical polymerizable substance and the film-forming material as needed.

[0075] As a specific example of the curing agent contained in the second composition which generates a free radical by heating, diacyl peroxide, peroxydicarbonate, peroxyester, peroxyketal, dialkyl peroxide, hydroperoxide, silyl peroxide, and the like can be exemplified. In addition, from the viewpoint of inhibiting corrosion of the circuit electrode, a curing agent having a concentration of chloride ions and organic acid of 5000 ppm or less is preferred, and further, a curing agent which generates little organic acid after decomposition by heating is more preferred. As a specific example of such a curing agent, peroxyester, dialkyl peroxide, hydroperoxide, silyl peroxide, and the like can be exemplified, and a curing agent selected from peroxyesters which can obtain high reactivity is more preferred. Note that the above curing agents can be appropriately used in combination.

[0076] As the peroxide ester, there can be mentioned cumyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, 1-cyclohexyl-1-methylethyl peroxyneodecanoate, t-hexyl peroxyneodecanoate, t-butyl peroxypivalate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, 1-cyclohexyl-1-methylethyl peroxy-2-ethylhexanoate, t-hexyl peroxy-2-ethylhexanoate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxyisobutyrate, 1,1-bis(t-butylperoxy)cyclohexane, t-hexyl peroxyisopropylmonocarbonate, t-butyl peroxy-3,5,5-trimethylhexanoate, t-butyl peroxylaurate, 2,5-dimethyl-2,5-di(m-methylbenzoylperoxy)hexane, t-butyl peroxyisopropylmonocarbonate, t-butyl peroxy-2-ethylhexylmonocarbonate, t-hexyl peroxybenzoate, t-butyl peroxyacetate, and the like. In addition to the above peroxide esters, a curing agent that generates a free radical by heating, for example, a compound described in International Publication No. 2009 / 063827 can be suitably used. They can be used alone or in combination of two or more.

[0077] These curing agents can be used alone or in combination of two or more, and further, a decomposition accelerator, a decomposition inhibitor, or the like can be used in combination. In addition, these curing agents can be coated with a polyurethane-based or polyester-based high molecular substance or the like and subjected to microcapsulation. The curing agent subjected to microcapsulation can have a prolonged service life, and thus is preferred.

[0078] In the circuit connecting material of the present embodiment, a film forming material can be added as needed and used. The film forming material is a substance that, in the case where a liquid substance is solidified and formed into a film shape, facilitates the handling of the film in a normal state (normal temperature and normal pressure) and imparts mechanical properties and the like, such as non-easy breaking, cracking, or tackiness, to the film. As the film forming material, there can be mentioned phenoxy resin, polyvinyl formal resin, polystyrene resin, polyvinyl butyral resin, polyester resin, polyamide resin, xylene resin, polyurethane resin, and the like. Among these, from the viewpoint of adhesiveness, compatibility, heat resistance, and mechanical strength, phenoxy resin is preferred.

[0079] The phenoxy resin is a resin obtained by reacting a 2-functional phenol with an epihalohydrin until polymerization, or by polyaddition of a 2-functional epoxy resin with a 2-functional phenol. The phenoxy resin can be obtained, for example, by reacting 1 mole of a 2-functional phenol with 0.985 to 1.015 moles of an epihalohydrin in the presence of a catalyst such as an alkali metal hydroxide, in a non-reactive solvent, at a temperature of 40 to 120°C. Further, as the phenoxy resin, from the viewpoint of mechanical properties and thermal properties of the resin, it is particularly preferable to set the equivalent ratio of the 2-functional epoxy resin to the 2-functional phenol to be epoxy group / phenolic hydroxyl group = 1 / 0.9 to 1 / 1.1, to perform a polyaddition reaction in the presence of a catalyst such as an alkali metal compound, an organic phosphorus compound, a cyclic amine compound, or the like, in an organic solvent such as an amide-based, ether-based, ketone-based, lactone-based, alcohol-based, or the like, having a boiling point of 120°C or higher, under the condition that the solid content of the reaction is 50% by mass or less, and heating to 50 to 200°C. The phenoxy resin can be used alone or in combination with two or more.

[0080] As the 2-functional epoxy resin described above, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a bisphenol AD type epoxy resin, a bisphenol S type epoxy resin, a biphenyl diglycidyl ether, a methyl-substituted biphenyl diglycidyl ether, or the like can be exemplified. The 2-functional phenol is a substance having two phenolic hydroxyl groups. As the 2-functional phenol, for example, a bisphenol such as a hydroquinone, bisphenol A, bisphenol F, bisphenol AD, bisphenol S, bisphenol fluorene, methyl-substituted bisphenol fluorene, dihydroxy biphenyl, methyl-substituted dihydroxy biphenyl, or the like can be exemplified. The phenoxy resin can also be modified (for example, epoxy-modified) with a radically polymerizable functional group, or other reactive compounds.

[0081] When the total mass of the circuit connecting material is set to 100 parts by mass, the blending amount of the film forming material is preferably 10 to 90 parts by mass, and more preferably 20 to 60 parts by mass.

[0082] The circuit connecting material of the present embodiment can further contain a polymer or a copolymer having at least one of an acrylic acid, an acrylate, a methacrylate, and an acrylonitrile as a monomer component. Here, from the viewpoint of excellent stress relaxation, the circuit connecting material preferably contains, in combination, a copolymer-based acrylic rubber or the like, the copolymer-based acrylic rubber containing a glycidyl acrylate and / or a glycidyl methacrylate containing a glycidyl ether group. From the viewpoint of improving the cohesiveness of the adhesive composition, the weight average molecular weight of these acrylic rubbers is preferably 200,000 or more.

[0083] The circuit connecting material of the present embodiment can further contain rubber microparticles, a filler, a softening agent, an accelerator, an anti-aging agent, a coloring agent, a flame retardant, a thixotropic agent, a coupling agent, a phenol formaldehyde resin, a melamine resin, an isocyanate, or the like.

[0084] The rubber microparticles are preferably microparticles having an average particle diameter of less than or equal to twice the average particle diameter of the conductive particles to be compounded, and a storage modulus at normal temperature (25°C) of less than or equal to 1 / 2 the storage modulus at room temperature of the conductive particles and the adhesive composition. In particular, in the case where the material of the rubber microparticles is silicone, an acrylic emulsion, SBR, NBR, or polybutadiene rubber, it is appropriate to use either alone or in combination of two or more. These rubber microparticles crosslinked in three dimensions have excellent solvent resistance and are easily dispersed in the adhesive composition.

[0085] The filler can improve the connection reliability and the like of the electrical properties between the circuit electrodes. As the filler, for example, a substance having an average particle diameter of less than or equal to 1 / 2 the average particle diameter of the conductive particles can be appropriately used. In addition, in the case of using a particle having no conductivity in combination, a filler smaller than or equal to the average particle diameter of the particle having no conductivity can be used. The compounding amount of the filler is preferably 5 to 60 parts by mass with respect to 100 parts by mass of the adhesive composition. By being less than or equal to 60 parts by mass, there is a tendency to be able to more sufficiently obtain the effect of improving the connection reliability, and on the other hand, by being greater than or equal to 5 parts by mass, there is a tendency to be able to sufficiently obtain the effect of adding the filler.

[0086] As the coupling agent, a compound containing an amino group, a vinyl group, an acryloyl group, an epoxy group, or an isocyanate group is preferable because of the improvement in adhesion.

[0087] The circuit connecting material is a material that, after connection by which the relative circuit electrodes are connected by being subjected to melt flow, is cured to maintain the connection, and the flowability of the circuit connecting material is an important factor. As an index indicating the flowability, for example, the following index can be listed. That is, in the case where a 5 mm x 5 mm circuit connecting material having a thickness of 35 μm is sandwiched between two glass plates of 15 mm x 15 mm having a thickness of 0.7 mm and is subjected to heat and pressure under the conditions of 170°C, 2 MPa, and 10 seconds, the value of the flowability represented by the ratio of the main surface area (A) of the circuit connecting material before the heat and pressure to the main surface area (B) after the heat and pressure (B) / (A) is preferably 1.3 to 3.0, and more preferably 1.5 to 2.5. If it is greater than or equal to 1.3, there is a tendency that the flowability is appropriate and good connection is easily obtained, and if it is less than or equal to 3.0, there is a tendency that bubbles are less likely to be generated and the reliability is more excellent.

[0088] The elastic modulus of the circuit connecting material after curing is preferably 100 to 3000 MPa, and more preferably 500 to 2000 MPa, at 40°C. The elastic modulus of the circuit connecting material after curing can be measured, for example, using a dynamic viscoelasticity measuring device (DVE, DMA, or the like).

[0089] The circuit connecting material of the present embodiment is suitably used for COG (Chip on Glass) connection, FOB (Flexon Board) connection, FOG (Flex on Glass) connection, FOF (Flex on Flex) connection, FOP (Flex on Polymer) connection, COP (Chip on Polymer) connection, COF (Chip on Flex) connection, and the like.

[0090] The COG connection is, for example, a connection between a circuit electrode formed on an IC and a circuit electrode formed on a glass substrate constituting an organic EL panel or an LCD panel.

[0091] The FOB connection is, for example, a connection between a circuit electrode formed on a flexible substrate and a circuit electrode formed on a printed wiring board, which is represented by TCP (Tape Carrier Package), COF, and FPC. The FOG connection is, for example, a connection between a circuit electrode formed on a flexible substrate and a circuit electrode formed on a glass substrate constituting an organic EL panel or an LCD panel, which is represented by TCP, COF, and FPC. The FOF connection is, for example, a connection between a circuit electrode formed on a flexible substrate and a circuit electrode formed on a flexible substrate, which is represented by TCP, COF, and FPC. The FOP connection is a connection between a circuit electrode formed on a flexible substrate and a circuit electrode formed on a polymer substrate constituting an organic EL panel or an LCD panel. The COP connection is a connection between a circuit electrode formed on an IC and a circuit electrode formed on a plastic substrate. The COF connection is a connection between a circuit electrode formed on an IC and a circuit electrode formed on a flexible substrate.

[0092] <Connection Structure>

[0093] The circuit connection structure of the present embodiment has a first circuit member having a first circuit electrode, a second circuit member having a second circuit electrode, and a connection portion between the first circuit member and the second circuit member, which contains a cured product of the circuit connecting material. In the present embodiment, as a material of the circuit electrode, Ti, Al, Mo, Co, Cu, Cr, Sn, Zn, Ga, In, Ni, Au, Ag, V, Sb, Bi, Re, Ta, Nb, W, and the like can be used. From the viewpoint of achieving a balance between connection resistance and price, the thickness of the circuit electrode is preferably 100 to 5000 nm, and further preferably 100 to 2500 nm. In addition, the lower limit can be set to 500 nm.

[0094] The circuit connection structure of this embodiment can be manufactured as follows: a first circuit component having a first circuit electrode and a second circuit component having a second circuit electrode are arranged with the first circuit electrode facing the second circuit electrode, a circuit connection material is placed between the opposing first circuit electrode and the second circuit electrode, and then heated and pressurized to electrically connect the first circuit electrode and the second circuit electrode. Thus, the circuit connection material of this embodiment is useful as a material for bonding electrical circuits together.

[0095] More specifically, examples of circuit components include: semiconductor chips, resistor chips, capacitor chips, and other chip components; and substrates such as printed circuit boards. These circuit components typically have multiple (or sometimes a single) of the aforementioned circuit electrodes. By arranging at least a portion of these circuit electrodes facing each other and placing a circuit connection material between the facing circuit electrodes, at least one set of the circuit components is heated and pressurized, thereby electrically connecting the facing circuit electrodes to each other. At this time, the facing circuit electrodes are electrically connected to each other via conductive particles contained in the circuit connection material, while maintaining insulation between adjacent circuit electrodes. Thus, the circuit connection material of this embodiment exhibits anisotropic conductivity.

[0096] While referring to Figure 3 (a) to (c) will describe one embodiment of the manufacturing method of the circuit connection structure. Figure 3 (a) is a cross-sectional view of the process before the circuit components are connected to each other. Figure 3 (b) is a cross-sectional view of the process of connecting circuit components to each other. Figure 3 (c) is a cross-sectional view of the process after the circuit components are connected to each other.

[0097] First, such as Figure 3 As shown in (a), a circuit component 20 having circuit electrodes 21a and a circuit substrate 21b disposed on an organic EL panel 21, and a circuit component 30 having circuit electrodes 31a disposed on a substrate 31 are prepared. Then, a circuit connection material 5 pre-formed into a film is placed on the circuit electrodes 21a.

[0098] Next, as Figure 3As shown in (b), a substrate 31 with circuit electrodes 31a is placed on a circuit connection material 5 while the circuit electrodes 21a and 31a are aligned with each other, with the circuit connection material 5 positioned between the circuit electrodes 21a and 31a. It should be noted that the circuit electrodes 21a and 31a have a structure in which multiple electrodes are arranged along the depth direction (not shown). Since the circuit connection material 5 is film-like, it is easy to handle. Therefore, the circuit connection material 5 can be easily positioned between the circuit electrodes 21a and 31a, and the connection operation between the circuit components 20 and 30 can be easily performed.

[0099] Next, while heating, the circuit connection material 5 is connected along the organic EL panel 21 and the substrate 31. Figure 3 (b) is cured by applying pressure in the direction of arrow A. Thus, the desired result is obtained. Figure 3 The circuit components 20 and 30 shown in (c) are connected to each other via a cured circuit connection material 5a to form a circuit connection structure 50. As a curing process, one or both of heating and light irradiation may be used, depending on the adhesive composition used.

[0100] Example

[0101] The present disclosure is further illustrated below with examples. However, the present invention is not limited to these examples.

[0102] (1) Preparation of conductive particles

[0103] Prepare 11 types of conductive particles, A through K, as shown in Table 1 below. These conductive particles are all core-shell particles, consisting of a core containing a plastic particle and a shell containing a metal layer (nickel layer) covering the core particle. The conductivity of nickel is 14.5 × 10⁻⁶. 6 S / m. Among conductive particles A to K, conductive particles A to E and conductive particles H and J satisfy both the first and second conditions.

[0104] [Table 1]

[0105]

[0106] <Example 1>

[0107] (2) Fabrication of anisotropic conductive films

[0108] (Preparation of phenoxy resin solution)

[0109] 50g of phenoxy resin (product name: PKHC, manufactured by Union Carbide Corporation, weight average molecular weight 5000) was dissolved in a mixed solution of toluene / ethyl acetate = 50 / 50 (mass ratio) to prepare a phenoxy resin solution with a solid content of 40% by mass.

[0110] (Synthesis of urethane acrylate)

[0111] To a 2L four-necked flask equipped with a thermometer, a stirrer, an inactive gas inlet, and a reflux cooler, 4000 parts by mass of polycarbonate diol (manufactured by Aldrich Corporation, number average molecular weight Mn = 2000), 238 parts by mass of 2-hydroxyethyl acrylate, 0.49 parts by mass of p-benzene diol monomethyl ether, and 4.9 parts by mass of a tin-based catalyst were added to prepare a reaction solution. To the reaction solution heated to 70°C, 666 parts by mass of isophorone diisocyanate (IPDI) was added dropwise uniformly over 3 hours to allow the reaction to proceed. After the completion of the dropwise addition, the reaction was continued for 15 hours, and the reaction was considered to be completed when the NCO % (NCO content) became 0.2% by mass or less. Thus, a urethane acrylate was obtained. The NCO % was confirmed by a potentiometric automatic titrator (trade name: AT-510, manufactured by Kyoto Electronic Industrial Co., Ltd.). The weight average molecular weight of the urethane acrylate was 8500 (standard polystyrene conversion value) as a result of GPC analysis. The measurement conditions of GPC are shown in Table 2.

[0112] [Table 2]

[0113]

[0114] (Preparation of binder-containing liquid)

[0115] A phenoxy resin solution of 50 g of solid content, 30 g of the urethane acrylate, 15 g of an isocyanurate-type acrylate (product name: M-215, manufactured by Toagosei Co., Ltd.), 1 g of a phosphate-type acrylate, and 4 g of benzoyl peroxide (product name: NYPER BMT-K40, manufactured by NOF Corporation) as a free radical generator were mixed to prepare a binder-containing liquid.

[0116] (Production of anisotropic conductive film)

[0117] To 100 parts by mass of the binder-containing liquid, 5 parts by mass of the conductive particles A were added to prepare a circuit-connecting-material-containing liquid. The circuit-connecting-material-containing liquid was applied to a polyethylene terephthalate (PET) film of 50 μm in thickness on which one surface was surface-treated using an applicator, and then hot air drying was performed at 70°C for 3 minutes. Thus, an anisotropic conductive film of 20 μm in thickness was obtained on the PET film. When the total mass of the anisotropic conductive film was assumed to be 100 parts by volume, the contents of the binder component and the conductive particles were 97 parts by volume and 3 parts by volume, respectively.

[0118] (3) Production of connection structure (electrode top surface: titanium)

[0119] Each anisotropic conductive film with a PET film was cut into a predetermined size (width 1.5 mm x length 3 cm). The surface on which the anisotropic conductive film was formed (adhesive surface) was transferred to a glass substrate (thickness 0.7 mm) on which titanium (film thickness 50 nm) and aluminum (film thickness 250 nm) were sequentially coated from the top surface. The transfer conditions were set to 70°C, 1 MPa, and 2 seconds. After the PET film was peeled off, a flexible circuit board (FPC) having 600 tin-plated copper circuits with a pitch of 50 μm and a thickness of 8 μm was temporarily fixed to the anisotropic conductive film. The temporary fixing conditions were set to 24°C, 0.5 MPa, and 1 second. Subsequently, it was set in a formal press bonding device, and a silicone rubber sheet with a thickness of 200 μm was used as a buffer material, and heating and pressurization were performed at 170°C, 3 MPa, and 6 seconds from the FPC side by a heating tool to bond the entire width of 1.5 mm. Thus, a connection structure was obtained.

[0120] (4) Production of connection structure (electrode top surface: ITO)

[0121] Instead of the above glass substrate on which titanium and aluminum were sequentially coated from the top surface, a glass substrate on which ITO (film thickness 100 nm) was coated on the top surface was used, and otherwise, the same operations as above were performed to obtain a connection structure.

[0122] (5) Production of connection structure (electrode top surface: IZO)

[0123] Instead of the above glass substrate on which titanium and aluminum were sequentially coated from the top surface, a glass substrate on which IZO (film thickness 100 nm), Cr (film thickness 50 nm), and aluminum (film thickness 200 nm) were sequentially coated from the top surface was used, and otherwise, the same operations as above were performed to obtain a connection structure.

[0124] (6) Measurement of connection resistance

[0125] The connection resistance of the above two connection structures obtained was measured in the following manner. The resistance value between adjacent circuits of the FPC including the connection portion of the connection structure was measured by a multimeter (device name: TR6845, manufactured by Advantest Corporation). Note that the resistance at 40 points between adjacent circuits was measured, and the average value was calculated as the connection resistance. The results are shown in Table 3.

[0126] Examples 2 to 5 and Comparative Examples 1 and 2

[0127] Instead of the conductive particles A, the conductive particles B to K were used, respectively, and otherwise, the same operations as in Example 1 were performed to produce three connection structures, respectively, and their connection resistance was measured. The results are shown in Table 3.

[0128] [Table 3]

[0129]

[0130] Industrial applicability

[0131] According to the present disclosure, a method of providing a conductive particle having sufficiently high general-purpose for circuit electrodes possessed by circuit members to be connected can be provided. In addition, according to the present disclosure, a conductive particle, a circuit connecting material using the same, a connection structure, and a manufacturing method thereof can be provided.

[0132] Explanation of symbols

[0133] 1, 1a, 1b: conductive particle; 3, 4, 20, 30: circuit member; 3a, 4a, 21a, 31a: circuit electrode; 5: circuit connecting material; 5a: cured product of circuit connecting material; 10, 50: connection structure.

Claims

1. A method for sorting electrically conductive particles, comprising: a step of determining whether a metal constituting an outermost layer of an electrically conductive particle satisfies a first condition below, and a step of determining whether the electrically conductive particle satisfies a second condition below, electrically conductive particles satisfying both the first condition and the second condition are determined to be good, First condition: the elements constituting the outermost layer are analyzed, and the electrical conductivity at 20°C is determined to be less than or equal to 40 x 10 6 S / m depending on the kind of the element First condition: the elements constituting the outermost layer are analyzed, and the electrical conductivity at 20°C is determined to be less than or equal to 40 x 10 6 S / m the second condition: a volume-specific resistance determined by applying a load of 2 kN to 2.5 g of the electrically conductive particles is less than or equal to 15 mΩcm, the metal constituting the outermost layer of the electrically conductive particle includes Al, Ti, Cr, Fe, Co, Ni, Zn, Zr, Mo, Pd, In, Sn, W, or Pt.

2. A circuit connecting material for bonding circuit members to each other and electrically connecting circuit electrodes possessed by the respective circuit members to each other, comprising: an adhesive component that is cured by light or heat, and electrically conductive particles dispersed in the adhesive component, the electrically conductive particles are electrically conductive particles determined to be good by the method for sorting electrically conductive particles according to claim 1.

3. The circuit connecting material according to claim 2, which is formed in a film shape.

4. The circuit connecting material according to claim 2 or 3, the connection is a COG connection, a FOB connection, a FOG connection, a FOF connection, a FOP connection, a COP connection, or a COF connection.

5. A method for manufacturing a connection structure, comprising: a step of interposing a circuit connecting material according to any one of claims 2 to 4 between a pair of circuit members disposed facing each other; and a step of forming a connection portion by heating and pressurizing, the connection portion including a cured product of the circuit connecting material and interposed between the pair of circuit members, and bonding the circuit members to each other in a manner that circuit electrodes possessed by the respective circuit members are electrically connected to each other.

6. A connection structure, comprising: a pair of circuit members disposed facing each other; and a connection portion including a cured product of a circuit connecting material according to any one of claims 2 to 4 and interposed between the pair of circuit members, and bonding the circuit members to each other in a manner that circuit electrodes possessed by the respective circuit members are electrically connected to each other.

7. An electrically conductive particle determined to be good by a method for sorting electrically conductive particles, the method for sorting electrically conductive particles comprising: a step of determining whether a metal constituting an outermost layer of an electrically conductive particle satisfies a first condition below, and a step of determining whether the electrically conductive particle satisfies a second condition below, electrically conductive particles satisfying both the first condition and the second condition are determined to be good, First condition: the elements constituting the outermost layer are analyzed, and the electrical conductivity at 20°C is determined to be less than or equal to 40 x 10 6 S / m depending on the kind of the element First condition: the elements constituting the outermost layer are analyzed, and the electrical conductivity at 20°C is determined to be less than or equal to 40 x 10 6 S / m the second condition: a volume-specific resistance determined by applying a load of 2 kN to 2.5 g of the electrically conductive particles is less than or equal to 15 mΩcm, the metal constituting the outermost layer of the electrically conductive particle includes Al, Ti, Cr, Fe, Co, Ni, Zn, Zr, Mo, Pd, In, Sn, W, or Pt.

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