Two-component curable conductive adhesive

Abstract

To provide a novel solventless two-liquid type conductive adhesive which has room temperature curability, excellent handling ability, excellent rapid curability, high bond strength, and excellent conductivity.SOLUTION: Provided is a two-liquid type conductive adhesive which comprises at least: a first agent containing dendritic silver-coated copper powder and an epoxy resin which is liquid at 25°C; and a second agent containing dendritic silver-coated copper powder and a trifunctional or more thiol compound which is liquid at 25°C, and which satisfies the following conditions 1 and 2. Condition 1: the dendritic silver-coated copper powder is contained in a cured coating film of the two-liquid type conductive adhesive so that its content becomes 60 mass% to 80 mass%. Condition 2: a curing catalyst is contained in the first agent and / or the second agent.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a two-component curable conductive adhesive.

Background Art

[0002] As conductive adhesives, those with various compositions are known and are used in various applications. For example, they are used for die bonding in wearable devices, LEDs, etc., and for various conductive connections. On the other hand, hitherto, in a solar cell module, a tab wire made of a ribbon-shaped copper foil coated with solder as an interconnector is used, one end side thereof is connected to the front surface electrode of one solar cell, and the other end side is connected to the back surface electrode of an adjacent solar cell, thereby connecting each solar cell in series.

[0003] Patent Document 1 describes that a bus bar electrode formed by screen printing a silver paste on the light-receiving surface of a solar cell and a tab wire are soldered, and a silver electrode formed at the back surface connection portion of the solar cell and the tab wire are soldered to connect them. However, since soldering requires a high-temperature connection process of about 260°C, there is a concern that the connection reliability between the front surface electrode and the back surface electrode of the solar cell and the tab wire may be reduced due to warping of the solar cell, internal stress generated at the connection portion between the tab wire and the front surface electrode and the back surface electrode, and further residues of flux, etc.

[0004] Patent Document 2 describes the use of a conductive adhesive film that can be connected by thermocompression bonding at a relatively low temperature for the connection between the front and back electrodes of a solar cell and a tab wire. As the conductive adhesive film, a film formed by dispersing spherical or flaky conductive particles with an average particle size on the order of several μm in a thermosetting binder resin composition is used. After the conductive adhesive film is interposed between the front and back electrodes and the tab wire, it is thermocompressed from above the tab wire, so that the binder resin exhibits fluidity and flows out between the electrodes and the tab wire, and the conductive particles establish electrical conduction between the electrodes and the tab wire. In this state, the binder resin is thermoset. Thereby, strings in which a plurality of solar cells are connected in series by tab wires are formed. However, in recent years, in the connection process of tab wires, shortening of the tact time has been demanded, and the conductive adhesive film is insufficient in shortening the tact time (i.e., curability).

[0005] Patent Document 3 describes a low-temperature curable conductive adhesive comprising at least an epoxy resin, a curing agent, and conductive particles, wherein the curing agent contains an imidazole-based curing agent and an organic acid dihydrazide curing agent.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] Conventionally, there has been no known electrically conductive adhesive that has room temperature curability, excellent handleability (processability), excellent instant curability (shortening of tact time), excellent bonding strength (having connection reliability), and excellent electrical conductivity (low volume resistivity). An object of the present invention is to provide a novel solvent-free two-component curable electrically conductive adhesive that has room temperature curability, excellent handleability, excellent instant curability, high bonding strength, and excellent electrical conductivity. [Means for Solving the Problems]

[0008] As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by using a two-component curable electrically conductive adhesive having a specific composition, and have completed the present invention. Specifically, it is as follows. [1] It is composed of at least a first agent containing dendritic silver-coated copper powder and an epoxy resin that is liquid at 25°C, and a second agent containing dendritic silver-coated copper powder and a trifunctional or higher thiol compound that is liquid at 25°C, satisfying the following Conditions 1 and 2; Condition 1: The dendritic silver-coated copper powder is contained in the cured coating film of the two-component curable electrically conductive adhesive so as to be 60% by mass or more and 80% by mass or less, Condition 2: A curing catalyst is contained in the first agent and / or the second agent, A two-component curable electrically conductive adhesive satisfying the above conditions. [2] The two-component curable electrically conductive adhesive according to [1], wherein a dispersant is contained in the second agent. [3] The two-component curable electrically conductive adhesive according to [1] or [2], wherein the average particle diameter of the dendritic silver-coated copper powder is 1 μm or more and 11 μm. [4] The two-component curable electrically conductive adhesive according to any one of [1] to [3], wherein the epoxy resin that is liquid at 25°C is a bisphenol A type epoxy resin. [Advantages of the Invention]

[0009] The present invention provides a novel solvent-free two-component curable conductive adhesive having room temperature curability, excellent handleability, immediate curability, high bonding strength (adhesion) to various substrates, and excellent conductivity. The two-component curable conductive adhesive of the present invention is useful as a circuit connection material and a printed electronics material, and is extremely useful as a conductive adhesive used for die bonding of solar cells, wearable devices, LEDs, etc.

Mode for Carrying Out the Invention

[0010] Hereinafter, the two-component curable conductive adhesive of the present invention will be described in detail.

[0011] [Two-Component Curable Conductive Adhesive] The two-component curable conductive adhesive of the present invention uses dendritic silver-coated copper powder as at least a part of the conductive powder, and comprises a first agent containing dendritic silver-coated copper powder and an epoxy resin that is liquid at 25°C, and a second agent containing dendritic silver-coated copper powder and a trifunctional or higher thiol compound that is liquid at 25°C, and satisfies the following conditions 1 and 2; Condition 1: It is contained such that the dendritic silver-coated copper powder in the cured coating film of the two-component curable conductive adhesive is 60% by mass or more and 80% by mass or less. Condition 2: A curing catalyst is contained in the first agent and / or the second agent. It is a two-component curable conductive adhesive that satisfies the above conditions.

[0012] <Dendritic Silver-Coated Copper Powder> The dendritic silver-coated copper powder is obtained by coating the surface of dendritic copper powder with silver. By using dendritic silver-coated copper powder obtained by coating dendritic copper powder with silver, the volume resistivity can be lowered and the bonding strength (adhesion) can be improved. There are no particular limitations on the method for producing the dendritic silver-coated copper powder. For example, methods such as electroplating dendritic copper powder with silver and substituting copper on the surface of dendritic copper powder with silver by a substitution reaction can be mentioned.

[0013] The average particle size of the dendritic silver-coated copper powder is not particularly limited. For example, it is 1 μm or more, preferably 2 μm or more, more preferably 3 μm or more, and for example, it is 15 μm or less, preferably 13 μm or less, more preferably 11 μm or less. Here, the average particle size of the conductive powder such as the dendritic silver-coated copper powder in this specification is the volume cumulative particle size D at 50% by volume of the cumulative volume measured by the laser diffraction scattering particle size distribution measurement method. 50 is the value of. If the average particle size of the dendritic silver-coated copper powder is larger than 15 μm, there is a risk that the wiring pattern is likely to be disconnected. Further, if the average particle size of the dendritic silver-coated copper powder is smaller than 1 μm, the core copper may be exposed and copper may be oxidized from this portion, and the specific resistance of the wiring pattern may increase over time.

[0014] The silver content in the dendritic silver-coated copper powder is not particularly limited. For example, it is 1% by mass or more, preferably 3% by mass or more, more preferably 5% by mass or more, and for example, it is 40% by mass or less, preferably 35% by mass or less, more preferably 30% by mass or less. When the silver content is less than 1% by mass, there is a risk that the core copper is exposed, and there is a risk that the specific resistance of the wiring pattern increases over time. Further, when the silver content is more than 40% by mass, the possibility of ion migration increases.

[0015] Specific examples of the dendritic silver-coated copper powder include at least one selected from ACBY-2, ACAX-225 (manufactured by Mitsui Mining & Smelting Co., Ltd.), and the like. The dendritic silver-coated copper powder is contained in both the first agent and the second agent of the two-component curable conductive adhesive.

[0016] The dendritic silver-coated copper powder is contained in the cured coating film of the two-component curable conductive adhesive in an amount of 60% by mass or more and 80% by mass or less. When the content of the dendritic silver-coated copper powder is 60% by mass or more in the cured coating film of the two-component curable conductive adhesive, the conductivity and thermal conductivity of the cured film of the two-component curable conductive adhesive are improved, and the heat dissipation property can be improved. When it is 80% by mass or less, the adhesion of the cured film of the two-component curable conductive adhesive to the adherend can be ensured.

[0017] <Epoxy resin in liquid state at 25°C> As the epoxy resin in liquid state at 25°C, it is an epoxy resin having two or more glycidyl groups in one molecule. If it is in liquid state at a temperature of 25°C and a pressure of 10 5 Pa, the molecular weight and molecular structure are not particularly limited.

[0018] Examples of the epoxy resin in liquid state at 25°C include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, naphthalene type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, phenol novolac type epoxy resin, alicyclic epoxy resin having an ester skeleton, cyclohexanedimethanol type epoxy resin, and epoxy resin having a butadiene structure. These may be used alone or in combination of two or more. Among these, bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol AF type epoxy resin are preferred.

[0019] Specific examples of the liquid epoxy resin at 25°C include, for example, "HP4032", "HP4032D", "HP4032SS" (naphthalene-type epoxy resin) manufactured by DIC Corporation; "828US", "jER828EL" (bisphenol A-type epoxy resin), "jER807" (bisphenol F-type epoxy resin), "jER152" (phenol novolak-type epoxy resin), "630", "630LSD" manufactured by Mitsubishi Chemical Corporation; "EP-3980S" (glycidylamine-type epoxy resin) manufactured by ADEKA Corporation; "ZX1059" (a mixture of bisphenol A-type epoxy resin and bisphenol F-type epoxy resin) manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.; "EX-721" (glycidyl ester-type epoxy resin) manufactured by Nagase ChemteX Corporation; "Celoxide 2021P" (alicyclic epoxy resin having an ester skeleton), "PB-3600" (epoxy resin having a butadiene structure) manufactured by Daicel Corporation; "ZX1658", "ZX1658GS" (liquid 1,4-glycidylcyclohexane) manufactured by Nippon Steel Chemical Co., Ltd., etc. These may be used alone or in combination of two or more.

[0020] The liquid epoxy resin at 25°C can be contained in both the first agent and the second agent of the two-component curable conductive adhesive, and can also be contained only in the first agent. Preferably, it is contained in both the first agent and the second agent. The content of the liquid epoxy resin in the two-component curable conductive adhesive at 25°C is not particularly limited. Assuming the total of dendritic silver-coated copper powder, liquid epoxy resin at 25°C, trifunctional or higher thiol compound at 25°C, and curing catalyst is 100% by mass, for example, it is 10% by mass or more, preferably 15% by mass or more, and for example, 30% by mass or less, preferably 25% by mass or less.

[0021] <Trifunctional or higher thiol compound in a liquid state at 25°C> The trifunctional or higher thiol compound in a liquid state at 25°C can be used as a curing agent for the liquid epoxy resin at 25°C. Examples of the trifunctional or higher thiol compound in a liquid state at 25°C are thiol compounds having three or more primary to tertiary thiol groups in one molecule, at a temperature of 25°C and a pressure of 105 If it is liquid at Pa, the molecular weight and molecular structure are not particularly limited.

[0022] Specific examples of the trifunctional or higher-functional thiol compound having a primary thiol group include, for example, trifunctional thiol compounds such as trimethylolethane tris(3-mercaptopropionate), trimethylolpropane trimercaptoacetate, trimethylolpropane tris(3-mercaptopropionate), trimethylolpropane tris(4-mercaptobutyrate), tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, tris-[(3-mercaptobutyryloxy)-ethyl]-isocyanurate, glycerol tris-(3-mercaptopropionate), glycerol tris-(4-mercaptobutyrate); tetrafunctional thiol compounds such as pentaerythritol tetramercaptoacetate, pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(4-mercaptobutyrate); polyfunctional thiol compounds having more than tetrafunctionality such as dipentaerythritol hexamercaptoacetate, dipentaerythritol hexakis(3-mercaptopropionate), dipentaerythritol hexakis(4-mercaptobutyrate). These may be used alone or in combination of two or more.

[0023] Specific examples of the polyfunctional thiol compound having a secondary thiol group and having three or more functional groups include, for example, trimethylolethane tris(3-mercaptobutyrate), trimethylolpropane tris(3-mercaptobutyrate), trimethylolpropane tris(2-mercaptopropionate), 1,4-bis(3-mercaptobutyryloxy)butane, 1,3,5-tris[2-(3-mercaptobutyryloxyethyl)]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, trimethylolpropane tris(4-mercaptovale rate), tris-[(3-mercaptobutyryloxy)-ethyl]-isocyanurate, trimethylolpropane tris(3-mercaptovale rate), trimethylolpropane tris(3-mercapto-3-phenylpropionate), tris-2-(3-mercapto-3-phenylpropionate)ethyl isocyanurate and other trifunctional thiol compounds; pentaerythritol tetrakis(3-mercaptobutyrate), pentaerythritol tetrakis(2-mercaptopropionate), pentaerythritol tetrakis(4-mercaptovale rate), pentaerythritol tetrakis(3-mercaptovale rate), pentaerythritol tetrakis(3-mercapto-3-phenylpropionate) and other tetrafunctional thiol compounds; dipentaerythritol hexakis(3-mercaptobutyrate), dipentaerythritol hexakis(2-mercaptopropionate), dipentaerythritol hexakis(4-mercaptovale rate), dipentaerythritol hexakis(3-mercaptovale rate), dipentaerythritol hexakis(3-mercapto-3-phenylpropionate) and other polyfunctional thiol compounds having more than tetrafunctionality, and the like. These may be used alone or in combination of two or more.

[0024] Specific examples of the thiol compound having a tertiary thiol group include trifunctional thiol compounds such as trimethylolethane tris(2-mercaptoisobutyrate), trimethylolpropane tris(2-mercaptoisobutyrate), trimethylolethane tris(3-mercapto-3-methylbutyrate), trimethylolpropane tris(3-mercapto-3-methylbutyrate); tetrafunctional thiol compounds such as pentaerythritol tetrakis(2-mercaptoisobutyrate), pentaerythritol tetrakis(3-mercapto-3-methylbutyrate); polyfunctional thiol compounds having more than tetrafunctionality such as dipentaerythritol hexakis(2-mercaptoisobutyrate), dipentaerythritol hexakis(3-mercapto-3-methylbutyrate), etc. These may be used alone or in combination of two or more.

[0025] The trifunctional or higher-functional thiol compound that is liquid at 25°C can be contained in both the first agent and the second agent of the two-component curable conductive adhesive, and can also be contained only in the second agent. Preferably, it is contained only in the second agent.

[0026] The usage amount of the trifunctional or higher-functional thiol compound that is liquid at 25°C is not particularly limited. Assuming that the total of the dendritic silver-coated copper powder, the epoxy resin that is liquid at 25°C, the trifunctional or higher-functional thiol compound that is liquid at 25°C, and the curing catalyst is 100% by mass, for example, it can be 30% by mass or more, preferably 25% by mass or more, and for example, 50% by mass or less, preferably 45.0% by mass or less. Also, with respect to 1 equivalent of epoxy groups of an epoxy resin that is liquid at 25°C, the thiol groups of a trifunctional or higher functional thiol compound that is liquid at 25°C are, for example, 0.7 equivalent or more, preferably 0.8 equivalent or more, more preferably 0.9 equivalent or more, and for example 1.5 equivalents or less, preferably 1.4 equivalents or less, more preferably 1.1 equivalents or less, and most preferably 1.0 equivalent. When it is less than 0.7 equivalent with respect to 1 equivalent of epoxy groups, the immediate curability of the conductive resin composition may decrease, it may take time to cure, or there may be a risk of poor curing of the coating film. When it exceeds 1.5 equivalents, there may be a risk of poor curing of the coating film and a decrease in the coating film strength due to the influence of unreacted curing agent that becomes excessive.

[0027] <Curing catalyst> The two-component curable conductive adhesive of the present invention contains a curing catalyst for accelerating the curing of the epoxy resin and the curing agent.

[0028] Specific examples of the curing catalyst include, for example, ethylenediamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, etc., aliphatic tertiary amines such as triethylamine, tripropylamine, tributylamine, dimethylbutylamine, dimethylpentylamine, dimethylcyclohexylamine, etc., dimethylbenzylamine, dimethylaminomethylphenol, dimethylamino-p-cresol, piperidine, α-picoline, pyridine, 2,4,6-tris(dimethylaminomethyl)phenol, 3,4,5-tris(dimethylaminomethyl)phenol, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, N-aminoethylpiperazine, 1,3,6-trisaminomethylhexane, m-xylenediamine, p-xylenediamine, N-(2-aminoethyl)piperazine, m-phenylenediamine, p-phenylenediamine, diaminophenylmethane, methylenedianiline, 2,4-toluenediamine, 2,4-diaminoanisole, 2,4-toluenediamine, 2,4-diaminodiphenylamine, 4,4'-methylenedianiline, 1,3-diaminocyclohexane, 3,9-bis(3-aminopropyl)-2,4,8,10-tetrapyrrolo[5,5]undecane, 1,8-diazabicyclo[5,4,0]undecene-7 or polyamine, polyamideamine, polyamide, modified polyamine, modified polyamideamine, modified polyamide, etc. These may be used alone or in combination of two or more. Among these curing catalysts, 2,4,6-tris(dimethylaminomethyl)phenol is preferably used from the viewpoints of catalyst performance and viscosity.

[0029] The curing catalyst can be contained in both the first agent and the second agent of the two-component curing conductive adhesive, and can also be contained in only one of the first agent or the second agent. Preferably, it is contained in only one of the first agent or the second agent. The content of the curing catalyst in the two-component curable conductive adhesive is not particularly limited. Taking the total of dendritic silver-coated copper powder, an epoxy resin that is liquid at 25°C, a trifunctional or higher thiol compound that is liquid at 25°C, and the curing catalyst as 100% by mass, for example, it is 0.005% by mass or more, preferably 0.01% by mass or more, and for example, 3.0% by mass or less, preferably 2.0% by mass or less.

[0030] <Dispersant> The two-component curable conductive adhesive of the present invention may contain a dispersant as necessary to prevent aggregation of the dendritic silver-coated copper powder.

[0031] Specific examples of the dispersant include, for example, Solsperse 9000, Solsperse 12000, Solsperse 17000, Solsperse 20000, Solsperse 21000, Solsperse 24000, Solsperse 26000, Solsperse 27000, Solsperse 28000, Solsperse 32000, Solsperse 35100, Solsperse 54000, SolSix 250 (manufactured by Lubrizol Japan Co., Ltd.), EFKA 4008, EFKA 4009, EFKA 4010, EFKA 4015, EFKA 4046, EFKA 4047, EFKA 4060, EFKA 4080, EFKA 7462, EFKA 4020, EFKA 4050, EFKA 4055, EFKA 4400, EFKA 4401, EFKA 4402, EFKA 4403, EFKA 4300, EFKA 4330, EFKA 4340, EFKA 6220, EFKA 6225, EFKA 6700, EFKA 6780, EFKA 6782, EFKA8503 (manufactured by Efka Additives Co., Ltd. as above), Adisper PA111, Adisper PB711, Adisper PB821, Adisper PB822, Adisper PN411, Feimex L-12 (manufactured by Ajinomoto Fine-Techno Co., Inc. as above), DISPERBYK-101, DISPERBYK-102, DISPERBYK-106, DISPERBYK-108, DISPERBYK-111, DISPERBYK-116, DISPERBYK-130, DISPERBYK-140, DISPERBYK-142, DISPERBYK-145, DISPERBYK-161, DISPERBYK-162, DISPERBYK-163, DISPERBYK-164, DISPERBYK-166, DISPERBYK-167, DISPERBYK-168, DISPERBYK-170, DISPERBYK-171, DISPERBYK-174, DISPERBYK-180, DISPERBYK-182, DISPERBYK-192, DISPERBYK-193, DISPERBYK-2000, DISPERBYK-2001, DISPERBYK-2020, DISPERBYK-2025, DISPERBYK-2050, DISPERBYK-2070, DISPERBYK-2155, DISPERBYK-2164, DISPERBYK-220S, DISPERBYK-300, DISPERBYK-306, DISPERBYK-320, DISPERBYK-322, DISPERBYK-325, DISPERBYK-330, DISPERBYK-340, DISPERBYK-350, DISPERBYK-377, DISPERBYK-378, DISPERBYK-380N, DISPERBYK-410, DISPERBYK-425, DISPERBYK-430 (manufactured by BYK-Chemie Japan Co., Ltd. as above), etc. may be mentioned. These may be used individually by one kind or in combination of two kinds or more.

[0032] The dispersant can be contained in both the first agent and the second agent of the two-component curable conductive adhesive, and can also be contained in only either the first agent or the second agent. Preferably, it is contained in only either the first agent or the second agent. For example, it can be contained in only the second agent. The content of the dispersant in the two-component curable conductive adhesive is not particularly limited. Taking the total of dendritic silver-coated copper powder, an epoxy resin that is liquid at 25°C, a polyfunctional thiol compound with three or more functional groups that is liquid at 25°C, a curing catalyst, and a dispersant as 100% by mass, for example, it is 3.0% by mass or less, preferably 2.0% by mass or less, more preferably 1.5% by mass or less.

[0033] <Other components> The two-component curable conductive adhesive of the present invention may, if necessary and within the range where the performance does not deteriorate, contain resins other than epoxy resins, organic acid compounds, pigments, fillers, antioxidants, corrosion inhibitors, surfactants, defoamers, dispersants, viscosity modifiers (thixotropy modifiers), adhesion promoters, coupling agents, anti-settling agents, etc., surfactants, pH adjusters (amine compounds), leveling agents, ultraviolet absorbers, antioxidants, flame retardants, etc. One or more various additives selected from the group consisting of can be mixed as "other components".

[0034] The above-mentioned other components can be contained in both the first agent and the second agent of the two-component curable conductive adhesive, or can be contained in only one of the first agent or the second agent. The content of the above-mentioned other components in the total solid content of the two-component curable conductive adhesive is not particularly limited. The blending amount can be appropriately optimized according to the required properties and the like.

[0035] <Method for preparing two-component curable conductive adhesive> The method for preparing the two-component curable conductive adhesive resin composition of the present invention is not particularly limited. For example, a method of separately manufacturing the first agent and the second agent and mixing the first agent and the second agent before use to prepare the two-component curable conductive adhesive resin composition of the present invention is preferable.

[0036] The preparation method of the first agent is not particularly limited. For example, there is a method of adding a dendritic silver-coated copper powder and an epoxy resin that is liquid at 25°C as essential components, and adding additive components in any order to a mixing container and mixing them. When mixing, for example, one or more mixers such as a ball mill, a roll mill, a bead mill, a planetary mixer, a tumbler, a stirrer, a stirrer, a mechanical homogenizer, an ultrasonic homogenizer, a high-pressure homogenizer, a paint shaker, a V-type blender, a Nauta mixer, a Banbury mixer, a rotating and revolving mixer, a kneading roll, a single-screw or twin-screw extruder can be used.

[0037] The preparation method of the second agent is not particularly limited. For example, there is a method of adding a dendritic silver-coated copper powder, a curing agent, and a curing catalyst as essential components, and adding additive components such as a dispersant in any order to a mixing container and mixing them. The mixer used for mixing can be the same as the mixer used in the preparation method of the first agent. The temperature when preparing the first agent and the second agent (the temperature when mixing each component) is not particularly limited. If necessary, heating, cooling, etc. can be performed, and for example, it can be 10°C or higher and 40°C or lower.

[0038] <Coating method and usage method of two-component curable conductive adhesive> The coating method of the two-component curable conductive adhesive of the present invention is not particularly limited. For example, one or more selected from the group consisting of a pen, a spatula, a brush, a roll, a die coat, a knife coater, a slot die coater, a slit coat, a lip coater, a roll coater, a flow coater, a spray coater, a bar coater, a dispenser, dipping, extrusion coating, screen printing, inkjet printing, flexographic printing, gravure printing, etc. can be mentioned.

[0039] For the two-component curable conductive adhesive of the present invention, there are methods such as applying the first agent to the bonding surface of one adherend and the second agent to the bonding surface of the other adherend, and then bonding the coated surfaces; after mixing the first liquid and the second liquid, using the above coating method to apply it to the coated surface of the adherend. Further, the two-component curable conductive adhesive of the present invention may be directly applied to a substrate, or may be applied to a release sheet (such as release paper or a resin release film) and then transferred to the substrate. Examples of the method for applying the adhesive to the substrate and the release sheet include the methods described above as the method for applying the two-component curable conductive adhesive of the present invention.

Examples

[0040] The present invention will be described in more detail with reference to the following examples. Note that the present invention is not limited to these examples. Unless otherwise specified, “%” means “mass %” and “part” means “part by mass”. In addition, all the numerical values related to the blending amounts of the respective components in Table 1 are in “parts” (parts by mass).

[0041] The materials used in the examples and comparative examples are as follows. <Conductive powder> · Conductive powder 1: Dendritic silver-coated copper powder (“ACAX-225” manufactured by Mitsui Mining & Smelting Co., Ltd.) (Average particle size 9.7 μm, tap density 1.4 g / cm 3 ) · Conductive powder 2: Dendritic silver-coated copper powder (“ACBY-2” manufactured by Mitsui Mining & Smelting Co., Ltd.) (Average particle size 6.5 μm, tap density 1.2 g / cm 3 ) · Conductive powder 3: Substantially spherical flake-shaped silver-coated copper powder (“1100YP” manufactured by Mitsui Mining & Smelting Co., Ltd.) (Average particle size 1.4 μm, tap density 3.3 g / cm 3 ) · Conductive powder 4: Flake-shaped silver-coated copper powder (“TFM-15F” manufactured by Toyo Aluminum Co., Ltd.) (Average particle size 15.0 μm, tap density 2.2 g / cm 3 ) · Conductive powder 5: Spherical silver-coated copper powder (“TFM-C05P” manufactured by Toyo Aluminum Co., Ltd.) (Average particle size 5.0 μm, tap density 4.9 g / cm 3 ) · Conductive powder 6: Flaky silver powder ("AgC-A" manufactured by Fukuda Metal Foil & Powder Co., Ltd.) (Average particle size 4.5 μm, tap density 2.9 - 3.6 g / cm 3 ) · Conductive powder 7: Dendritic silver powder ("GLC" manufactured by Mitsui Mining & Smelting Co., Ltd.) (Average particle size 2.0 μm, tap density 0.4 g / cm 3 ) · Conductive powder 8: Dendritic silver powder ("GKC" manufactured by Mitsui Mining & Smelting Co., Ltd.) (Average particle size 1.0 μm, tap density 4.9 g / cm 3 )

[0042] <Epoxy resin that is liquid at 25°C> · Epoxy resin 1: Bisphenol A type epoxy resin ("jER828" manufactured by Mitsubishi Chemical Corporation) · Epoxy resin 2: Chelate-modified epoxy resin ("EP-49-23" manufactured by ADEKA Corporation) <Trifunctional or higher thiol compound that is liquid at 25°C> · TMMP: Trimethylolpropane tris(3-mercaptopropionate) ("TMMP-LV" manufactured by SC Organic Chemicals Co., Ltd.) · TEMPIC: Tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate ("TEMPIC" manufactured by SC Organic Chemicals Co., Ltd.) · PEMP: Pentaerythritol tetrakis(3-mercaptopropionate) ("PEMP-LV" manufactured by SC Organic Chemicals Co., Ltd.) · DPMP: Dipentaerythritol hexakis(3-mercaptopropionate) ("DPMP" manufactured by SC Organic Chemicals Co., Ltd.) <Curing catalyst> · Curing catalyst: 2,4,6-Tris(dimethylaminomethyl)phenol (manufactured by Tokyo Chemical Industry Co., Ltd.) <Dispersant> · Dispersant: "DISPERBYK-2155" manufactured by BYK Japan K.K.

[0043] In the examples and comparative examples, the handling properties, immediate curability, bonding strength, and conductivity of the two-component curable conductive adhesive were measured and evaluated by the methods shown below. <Handling property> Using a rheometer (Rheometer DHR-2 manufactured by TA Instruments), the viscosity of the two-component curable conductive adhesive was measured under the conditions of a 20 mm cone plate and 25 °C, and the viscosity at a shear rate of 10 s -1 was evaluated based on the following criteria according to the viscosity at that time. S: Those with a viscosity of 250 Pa·s or less and good paste handling properties. A: Those with a viscosity greater than 250 Pa·s and less than or equal to 350 Pa·s and good paste handling properties. B: Those for which viscosity measurement is possible but exceeds 350 Pa·s. C: Those with too high viscosity to be measured. For the handling property, "S", "A", and "B" are considered qualified.

[0044] <Instant curability> On a glass substrate, a coating film of each two-component curable conductive adhesive with a thickness of 100 μm was formed, and it was evaluated based on the finger touch evaluation when left standing at 25 °C according to the following criteria. A: When finger touch evaluation was performed after standing for 2 hours, there was no tack. B: When finger touch evaluation was performed after standing for 2 hours, tack remained, but when finger touch evaluation was performed after standing for 24 hours, there was no tack. C: When finger touch evaluation was performed after standing for 24 hours, tack remained. For the instant curability, "A" and "B" are considered qualified.

[0045] <Bonding strength> A glass substrate (manufactured by Yutaka Panel Service) and a 5630 LED chip were bonded by applying each two-component curable conductive adhesive under the positive and negative electrodes so that the diameter was 1 mm and the thickness was 100 μm to prepare a measurement sample. For the obtained sample, a die shear test (0.1 mm / sec) was performed using a Bonding Tester PTR1102 manufactured by Resca, and it was evaluated based on the following criteria. S: With a bonding strength of 4,000 gf or more, having a strong bonding strength. A: The bonding strength is 1,000 gf or more and less than 4,000 gf, having sufficient bonding strength. B: The bonding strength is less than 1,000 gf, with weak bonding strength. C: It cannot be bonded. For the bonding strength, "S", "A", and "B" are qualified.

[0046] <Conductivity> On a printed wiring with a thickness of 1 mm and a volume resistivity of 3.0×10 ー4 cm·Ω, each two-component curable conductive adhesive was applied under each of the positive and negative electrodes to a diameter of 1 mm and a thickness of 100 μm, and 5630 LED chips were bonded to produce 5 measurement samples each. A voltage of 3 V was applied to both ends of the wiring using an LED checker, and the evaluation was carried out according to the following criteria. A: The LED lights up in all samples. C: There is a sample in which the LED does not light up. For conductivity, "A" is qualified.

[0047] [Examples 1 to 12, Comparative Examples 1 to 7] <Preparation of the First Agent> The components shown in Table 1 were blended in the amounts (parts by mass) shown in Table 1 to prepare A1 to A12 as the first agent.

[0048] [Table 1]

[0049] <Preparation of the Second Agent> The components shown in Tables 2 and 3 were blended in the amounts (parts by mass) shown in Tables 2 and 3 to prepare B1 to B18 as the second agent.

[0050] [Table 2]

[0051] [Table 3]

[0052] <Preparation of Two - Component Curing Conductive Adhesive> The first agent and the second agent were combined as shown in Tables 4 and 5, and the first agent and the second agent were blended so that the mass ratio was 1:1, and two - component curing conductive adhesives according to Examples 1 to 12 and Comparative Examples 1 to 7 were prepared. The content (mass %) of each component, handling property, immediate - curing property, bonding strength, and conductivity of each two - component curing conductive adhesive are shown together in Tables 4 and 5.

[0053]

Table 4

[0054]

Table 5

[0055] From Tables 4 and 5, it can be seen that the adhesives of Examples 1 to 12, which are two - component curing conductive adhesives according to the present invention, are excellent in handling property, immediate - curing property, bonding strength, and conductivity. On the other hand, it can be seen that Comparative Example 1 with a small content of conductive powder and Comparative Examples 2 to 7 that do not use dendritic silver - coated copper as the conductive powder have problems in one or more of the immediate - curing property, bonding strength, and conductivity.

Claims

1. It is at least composed of a first agent containing dendritic silver-coated copper powder and an epoxy resin that is liquid at 25°C, and a second agent containing dendritic silver-coated copper powder and a trifunctional or higher thiol compound that is liquid at 25°C. The following conditions 1 and 2; Condition 1: It is contained such that the dendritic silver-coated copper powder is 60% by mass or more and 80% by mass or less in the cured coating film of the two-component curable conductive adhesive. Condition 2: A curing catalyst is contained in the first agent and / or the second agent. A two-component curable conductive adhesive that satisfies the above.

2. The two-component curable conductive adhesive according to Claim 1, wherein a dispersant is contained in the second agent.

3. The two-component curable conductive adhesive according to Claim 1 or 2, wherein the average particle diameter of the dendritic silver-coated copper powder is 1 μm or more and 11 μm or less.

4. The two-component curable conductive adhesive according to any one of Claims 1 to 3, wherein the epoxy resin that is liquid at 25°C is a bisphenol A type epoxy resin.

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