Formulations for making highly conductive compositions after drying and firing

Abstract

Conductive composition containing (A) 1.005-1.74 mass% of bisphenol epoxy resin, (B) 0.015-less than 0.08 mass% of (meth) acrylic resin having a weight average molecular weight of 1000-400,000, (C) 0.5-0.86 mass% of polymer particles containing polybutadiene rubber, (D) 5-95 mass% of copper particles having an average particle diameter of 2-500 nm, (E) 0.9-4.8 mass% of silver particles having an average particle diameter of 2-500 nm, (F) 0.001-20 mass% of phosphorus-containing compound, (G) 0.0001-10 mass% of CuH, and (H) 0.1-1 mass% of solvent and 90 mass%.

Description

TECHNICAL FIELD

[0001] The present application relates to a formulation for producing a high-conductivity composition after drying and firing. BACKGROUND

[0002] As a method of forming a conductive pattern on a substrate, a method of printing a conductive composition on a substrate is known. As such a conductive composition for printing, for example, Patent Literature 1 discloses a conductive composition containing copper nanoparticles, a phosphorus-containing compound, and copper hydride (CuH).

[0003] However, such a conductive composition has room for improvement in adhesion to a substrate, particularly to a flexible printed circuit board (FPC), and conductivity.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent No. 6959977 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] The present application was made in view of the above circumstances, and aims to provide a conductive composition that has both excellent conductivity and adhesion.

[0009] SOLUTION TO PROBLEM

[0010] The present application includes the embodiments shown below.

[0011] [1] A conductive composition containing:

[0012] (A) a bisphenol-type epoxy resin 1.005 to 1.74 mass%,

[0013] (B) a (meth)acrylic resin having a weight average molecular weight of 1000 or more and 400,000 or less 0.015 mass% or more and less than 0.08 mass%,

[0014] (C) a polymer particle containing a polybutadiene rubber 0.5 to 0.86 mass%,

[0015] (D) copper particles having an average particle diameter of 2 to 500 nm 5 to 95 mass%,

[0016] (E) silver particles having an average particle diameter of 2 to 500 nm 0.9 to 4.8 mass%,

[0017] (F) a phosphorus-containing compound 0.001 to 20 mass%,

[0018] (G)CuH 0.0001~10% by mass, and

[0019] (H) Solvent 0.1~90 by mass.

[0020] [2] According to the conductive composition described in [1], wherein,

[0021] The polymer particles (C) have a core-shell structure comprising a core layer and a shell layer.

[0022] The aforementioned core layer contains polybutadiene rubber.

[0023] The aforementioned shell is composed of a polymer of vinyl monomers.

[0024] [3] The conductive composition according to [1] or [2], wherein the ratio of copper particles (D) to silver particles (E) ((D) / (E)) is 15.0 to 45.0 by mass.

[0025] [4] The conductive composition according to any one of [1] to [3], wherein the total content of copper particles (D) and silver particles (E) is 11.6 to 83.8 by mass.

[0026] The effects of the invention

[0027] The conductive composition according to the present invention provides excellent conductivity and adhesion. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the sample used in the conductivity evaluation of the embodiment. Detailed Implementation

[0029] The embodiments of the present invention will now be described in more detail.

[0030] The conductive composition of this embodiment contains: (A) 1.005 to 1.74% by mass of bisphenol-type epoxy resin, (B) 0.015% to less than 0.08% by mass of (meth)acrylic resin with a weight average molecular weight of 1,000 or more and 400,000 or less, (C) 0.5 to 0.86% by mass of polymer particles containing polybutadiene rubber, (D) 5 to 95% by mass of copper particles with an average particle size of 2 to 500 nm, (E) 0.9 to 4.8% by mass of silver particles with an average particle size of 2 to 500 nm, (F) 0.001 to 20% by mass of phosphorus-containing compound, (G) 0.0001 to 10% by mass of CuH, and (H) 0.1 to 90% by mass of solvent.

[0031] In the present specification, the "weight average molecular weight" can be measured by gel permeation chromatography (GPC), and is a value calculated using a differential refractive index detector (RI) as a detector, "TSKgel G4000HXL" manufactured by Tosoh Corporation as a column, tetrahydrofuran as a mobile phase, a measurement temperature of 40°C, a flow rate of 1.0 mL / min, an injection amount of 50 μL, a commercially available standard polystyrene, and a standard curve converted using polystyrene.

[0032] As the bisphenol-type epoxy resin (A), for example, a bisphenol A-type epoxy resin, a bisphenol F-type epoxy resin, a bisphenol S-type epoxy resin, or the like can be given. These resins can be used alone or in combination of a plurality of kinds.

[0033] The epoxy equivalent of the bisphenol-type epoxy resin (A) is not particularly limited, and is preferably 200 to 350 g / eq, more preferably 230 to 330 g / eq, and further preferably 240 to 320 g / eq. By making the epoxy equivalent 200 g / eq or more, cracking after printing on a substrate is less likely to occur. By making the epoxy equivalent 350 g / eq or less, adhesion to a substrate is improved, and in addition, long-term reliability of adhesion and conductivity is easily improved.

[0034] The content ratio of the bisphenol-type epoxy resin (A) is 1.005 to 1.74% by mass, preferably 1.131 to 1.678% by mass, and more preferably 1.257 to 1.616% by mass.

[0035] The (meth)acrylic resin (B) is a polymer containing at least an acrylate and / or a methacrylate as a constituent monomer, and for example, a polymer containing at least one selected from the group consisting of methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, and isobutyl methacrylate as a constituent monomer can be used. As a constituent monomer, a monomer other than an acrylate or a methacrylate can be contained within a range not deviating from the object of the present application. In the case of containing two or more kinds of monomers, it can be an alternating copolymer, can be a random copolymer, can be a block copolymer, or can be a graft copolymer. Here, the "(meth)acrylic resin" is a general term for "acrylic resin" and "methacrylic resin".

[0036] The weight average molecular weight of the (meth)acrylic resin (B) is 1000 or more, preferably 5000 or more, more preferably 7000 or more, and further preferably 10000 or more. In addition, it is 400,000 or less, preferably 200,000 or less, more preferably 150,000 or less, and further preferably 50,000 or less.

[0037] As such a (meth)acrylic resin (B), for example, a sintering paste copolymer of Japanese Patent Application Publication No. 2016-155920, Japanese Patent Application Publication No. 2015-59196, Japanese Patent Application Publication No. 2016-196606, WO 2016 / 132814, or the like can be used. In addition, a commercially available (meth)acrylic resin can also be used, and for example, "KC-1100", "KC-1700P" manufactured by Kyoeisha Chemical Co., Ltd. can be used.

[0038] The content ratio of the (meth)acrylic resin (B) is 0.015 mass% or more and less than 0.08 mass%, preferably 0.015 to 0.075 mass%, and more preferably 0.02 to 0.075 mass%.

[0039] As the polymer particles (C), it is only necessary to contain a polybutadiene rubber. It is preferable that the polymer particles (C) have a core-shell structure composed of a core layer and a shell layer, the core layer contains a polybutadiene rubber, and the shell layer is composed of a polymer of a vinyl-based monomer. As the vinyl-based monomer, for example, styrene, α-methylstyrene, monochlorostyrene, dichlorostyrene, and the like can be exemplified as styrene-based monomers; methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, and the like can be exemplified as (meth)acrylic-based monomers; acrylonitrile, methacrylonitrile, and the like can be exemplified as unsaturated nitrile-based monomers, and the like.

[0040] The polymer constituting the shell layer is preferably grafted to the core layer.

[0041] The content ratio of the polymer particles (C) is 0.5 to 0.86 mass%, preferably 0.557 to 0.827 mass%, and more preferably 0.619 to 0.796 mass%.

[0042] The average particle diameter of the polymer particles (C) is not particularly limited, and is preferably 30 to 500 nm, and more preferably 50 to 300 nm. Note that the "average particle diameter" of the polymer particles (C) refers to the number-based average particle diameter D50 (median particle diameter) measured by dispersing the polymer particles (C) in pure water using "MT3000II" manufactured by MicrotracBEL Corp. as a laser diffraction / scattering type particle size distribution measuring device.

[0043] The content ratio of the copper particles (D) having an average particle diameter of 2 to 500 nm is 5 to 95 mass%, preferably 40 to 79 mass%, more preferably 60 to 79 mass%, and further preferably 65 to 75 mass%.

[0044] The average particle diameter of the copper particles (D) is preferably 10 to 500 nm, more preferably 20 to 400 nm. Note that, in the present specification, the "average particle diameter" of metal particles means the number-based average particle diameter D50 (median particle diameter) measured using "MT3000II" manufactured by MicrotracBEL Corp. as a laser diffraction / scattering type particle size distribution measuring device, by adding butyl carbitol to the metal particles and dispersing for 10 minutes using an ultrasonic vibrator.

[0045] The shape of the copper particles (D) is not particularly limited, and spherical, flaky (scale-like), dendritic, or fibrous copper particles can be used, with spherical or flaky (scale-like) being preferred. Note that "spherical" metal particles include not only substantially spherical metal particles (atomized powder), but also substantially spherical metal particles such as substantially polyhedral spheres (reduced powder), amorphous shapes (electrolytic powder), and the like.

[0046] The content ratio of the silver particles (E) having an average particle diameter of 2 to 500 nm is 0.9 to 4.8% by mass, preferably 1.69 to 4.5% by mass, more preferably 1.69 to 4.2% by mass.

[0047] The average particle diameter of the silver particles (E) is preferably 30 to 400 nm, more preferably 60 to 300 nm.

[0048] The shape of the silver particles (E) is not particularly limited, and spherical, flaky (scale-like), dendritic, or fibrous silver particles can be used, with spherical or flaky (scale-like) being preferred. Note that "spherical" metal particles include not only substantially spherical metal particles (atomized powder), but also substantially spherical metal particles such as substantially polyhedral spheres (reduced powder), amorphous shapes (electrolytic powder), and the like.

[0049] The content ratio of the copper particles (D) to the silver particles (E) ((D) / (E)) is not particularly limited, and is preferably 15.0 to 45.0 by mass, more preferably 16.0 to 42.0 by mass.

[0050] The total content ratio of the copper particles (D) and the silver particles (E) is not particularly limited, and is preferably 11.6 to 83.8% by mass, more preferably 42 to 80% by mass, more preferably 62 to 78% by mass, further preferably 67 to 75% by mass.

[0051] The content ratio of the phosphorus-containing compound (F) is 0.001 to 20% by mass, preferably 0.003 to 20% by mass, more preferably 0.005 to 15% by mass, more preferably 1 to 14% by mass, more preferably 3 to 13% by mass, further preferably 5 to 12% by mass.

[0052] The phosphorous-containing compound (F) functions as an oxidizing agent for copper, oxidizing at least a portion of the copper (Cu) to cuprous ions (Cu + ), thereby forming copper hydride (CuH). CuH can form as nanoparticles or flakes containing essentially pure CuH, but most of the CuH forms as a continuous coating of CuH on copper (Cu) nanoparticles or as CuH domains (i.e., non-continuous coating) on at least a portion of the copper particles.

[0053] In some embodiments, the phosphorous-containing compound can be selected from the group consisting of hypophosphorous acid, phosphorous acid, phosphoric acid, pyrophosphoric acid (H4P2O7), tripolyphosphoric acid (H5P3O 10 ), tetrapolyphosphoric acid (H6P4O3), trimetaphosphoric acid (H3P3O9), phosphoric anhydride (P4O 10 ), polyphosphoric acid, hypodiphosphoric acid (H4P2O6), pyrophosphorous acid (H4P2O5), and metaphosphorous acid (HPO2), and mixtures thereof.

[0054] In other embodiments, the phosphorous-containing compound is hypophosphorous acid (HPA, also known as phosphinic acid) having the chemical formula HOP(O)H2.

[0055] In some embodiments, the ratio between the phosphorous-containing compound and the copper particles is preferably 0.001 to 0.2 in terms of mass ratio of phosphorous-containing compound / copper particles. That is, the phosphorous-containing compound is contained in a proportion of 0.1 mass% to 20 mass% relative to 1 mass part of the copper particles.

[0056] The proportion of the copper hydride (G) is 0.0001 to 10 mass%, preferably 0.0003 to 8 mass%, more preferably 1 to 7 mass%, and further preferably 3 to 6 mass%, regardless of its form.

[0057] While not wishing to be bound by theory, CuH can function as a protective layer against oxidation from copper to copper oxide. Further, when temporarily applied to a substrate and heated, CuH decomposes to provide an H2 atmosphere, which prevents the formation of copper oxide, enabling sintering of the copper particles based on intermetallic interactions.

[0058] In some embodiments, CuH can be crystalline or amorphous. In some other embodiments, CuH can be amorphous (e.g., characterized by not showing distinct peaks in XRD analysis).

[0059] The conductive composition of the present application is subjected to various thermal processes, and therefore the solvent (H) is desirably selected in such a manner that it has a boiling point that enables its evaporation upon exposure to the thermal process. In some embodiments, the solvent (H) can be selected in such a manner that it has a different evaporation rate and / or boiling point than the phosphorus-containing compound. For example, the solvent (H) can have a higher boiling point and / or a lower evaporation rate than the phosphorus-containing compound. In other embodiments, where the presence of the phosphorus-containing compound in the dried form is desired, the solvent (H) can be selected in such a manner that it has a lower boiling point and / or a higher evaporation rate than the phosphorus-containing compound. Specifically, the solvent (H) can be selected from the group consisting of water; alcohols such as terpineol, propylene glycol, and the like; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, ethylene glycol monohexyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mononormal-butyl ether, diethylene glycol monohexyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, and the like; glycol ether acetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monopropyl ether acetate, ethylene glycol monoisopropyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol monophenyl ether acetate, ethylene glycol monobenzyl ether acetate, ethylene glycol monohexyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mononormal-butyl ether acetate, diethylene glycol monohexyl ether acetate, diethylene glycol normal-butyl ether acetate, 1-methoxy methyl acetate, 3-methoxy propyl acetate, 3-ethoxy propyl acetate, 2-methoxy propyl acetate, 2-ethoxy propyl acetate, 2-methoxy butyl acetate, 2-ethoxy butyl acetate, 3-methoxy butyl acetate, 3-ethoxy butyl acetate, 4-methoxy butyl acetate, 4-ethoxy butyl acetate, 2-methoxy pentyl acetate, 2-ethoxy pentyl acetate, 3-methoxy pentyl acetate, 3-ethoxy pentyl acetate, 4-methoxy pentyl acetate, 4-ethoxy pentyl acetate, 5-methoxy pentyl acetate, 5-ethoxy pentyl acetate, 3-methoxy-3-methyl butyl acetate, and the like (preferably, alkoxy alkyl acetates), and mixtures thereof.

[0060] The solvent (H) can be contained in an amount of 0.1 to 90 mass%, preferably 5 to 80 mass%, more preferably 7 to 35 mass%, and further preferably 10 to 30 mass%. In one embodiment, the solvent (H) can be contained in an amount of 10 to 90 mass%.

[0061] The conductive composition of the present application is obtained by compounding the above-described components in prescribed amounts and mixing them sufficiently.

[0062] Note that the conductive composition of the present application can also be added with an additive that has been added to the same kind of conductive composition in the past within a range not departing from the object of the present application. As examples thereof, a curing catalyst, an antifoaming agent, a thickening agent, an adhesion-improving agent, a filler, an anti-settling agent, a coloring agent, an antioxidant, a plasticizer, an ultraviolet absorber, a flame retardant, and the like can be given.

[0063] The viscosity of the conductive composition of the present application is not particularly limited, and can be appropriately adjusted depending on the method of coating and the device used therefor. As a standard, the viscosity at a liquid temperature of 25°C is preferably 500 to 2500 dPa-s, and more preferably 1000 to 2000 dPa-s.

[0064] Note that, in the present specification, the "viscosity of the conductive composition" means the viscosity measured at a rotation speed of 10 rpm using a VISCOMETER TVB-10 (manufactured by Tokimec) main shaft No. 7.

[0065] The conductive composition of the present application can be applied to a substrate by any appropriate application method, such as inkjet printing, screen printing, spin coating, roll coating, spray coating, dip coating, flow coating, blade coating, dispensing, offset printing, pad printing, gravure printing, flexographic printing, stencil printing, stamping, xerography, photolithography, stamping, or any other appropriate application method.

[0066] The conductive pattern formed on the substrate can be formed on any appropriate substrate. As the substrate, a substrate that is flexible or rigid, stretchable or bendable, absorbent or non-absorbent, conductive or non-conductive, colored or transparent, and substantially two-dimensional (a thin flat substrate), three-dimensional curved surface (uneven), uniform or non-uniform surface, and the like can be used. The surface of the substrate can be of any smoothness. Most generally, the substrate can be a solid material such as a metal, glass, paper, semiconductor, polymeric material, ceramic surface, or a hybrid substrate containing several different materials. In particular, in the case where a polymeric material (e.g., a polyimide resin, a polyester resin, a polyamide resin, a polyamide-imide resin, or the like) used in a flexible printed circuit board (FPC) is used as the substrate, the adhesion-improving effect of the conductive composition of the present application is easily exerted. The material constituting the surface of the substrate to which the conductive composition is applied does not necessarily have to be the same material as the majority of the substrate. In some embodiments, the surface is substantially two-dimensional. In other embodiments, the surface is the surface of a three-dimensional object or article.

[0067] The substrate can have a uniform surface made of a single material (or a single composition), i.e., a substantially uniform surface roughness and / or a uniform thickness. However, in the context of the present disclosure, it is noted that the surface can also be non-uniform. That is, the surface of the substrate comprises at least two sections, which can differ in at least one of roughness, height, thickness, material or composition, etc., respectively. These at least two sections can be integral to each other or can have a gap therebetween (i.e., the sections of the substrate can be continuously associated). For example, by making one section of the substrate a tube and another section of the substrate a lid that is coupled to the tube, a small gap can be formed between the tube and the lid. Thus, the method of the present disclosure can be applied as a continuous printing to a substrate having multiple sections.

[0068] The "surface" can be the entire surface or any region thereof. The "region" can be of any size and structure. The regions can be continuous, can be integral to each other, or can be composed of several regions that are discontinuously spaced apart. In some embodiments, the regions are integral to each other. The term "region" also refers to a plurality of regions, at least two regions of the plurality differing from each other in at least one property (i.e., composition, texture, thickness, etc.). Thus, the term refers to a plurality of regions that also differ from other pluralities of regions according to the aforementioned properties, all of which are formed on the surface or a portion thereof.

[0069] After the conductive composition of the present disclosure is formed on the substrate in a pattern, a thermal process is applied. At this time, CuH is decomposed, and Cu nanoparticles are sintered to each other to obtain a conductive pattern.

[0070] The term "sintering" refers to the formation of a continuous matrix of the particulate material by a thermal process. If the particulate material is heated, diffusivity of metal atoms between adjacent contacting particles is promoted, thereby forming a continuous metal matrix with reduced porosity. By sintering, the non-conductive pattern composed of copper nanoparticles is converted into a continuous conductive copper matrix (or grid).

[0071] As a method for obtaining a conductive pattern on a substrate using the conductive composition of the present disclosure, the method comprises the following steps: Step 1, printing the conductive composition of the present disclosure onto at least a surface region of the substrate to obtain a pattern-loaded substrate; and Step 2, exposing the aforementioned pattern-loaded substrate to conditions that enable decomposition of CuH and sintering of copper and silver. The Step 2 is a period of between about 0.01 to 600 seconds. Thereby, a conductive pattern is obtained.

[0072] In some embodiments, conditions that enable decomposition of CuH and sintering of copper and silver can include exposure of the patterned substrate to temperatures above 125 °C. In other embodiments, the substrate can also be exposed to temperatures between about 125 °C and 500 °C. Additionally, it is also contemplated that sintering can be performed at temperatures above 500 °C or below 125 °C (e.g., between about 50 °C and 125 °C).

[0073] In some other embodiments, the patterned substrate is exposed to high temperatures (at least 125 °C) for a period of time between about 0.01 and 600 seconds. Without wishing to be bound by theory, the higher the sintering temperature, the shorter the period of time the patterned substrate is exposed to such temperatures. As will be appreciated by one skilled in the art, the pattern can be exposed to a single (i.e., uniform) temperature throughout the sintering temperature period, or it can be exposed to a varying temperature profile. For example, the sintering process can include two or more steps at different exposure periods and different temperatures. The temperature can vary slowly (i.e., the temperature can increase or decrease at various rates), or it can vary sharply (sharp increases or decreases in temperature).

[0074] Decomposition of CuH and sintering of copper and silver can be performed in an air atmosphere, or in a partial reducing atmosphere, i.e., in an atmosphere of gaseous reducing species. The reducing atmosphere can be obtained in situ by using the decomposition of CuH and phosphorous-containing compounds to form gaseous reducing agents (e.g., hydrogen as a decomposition product). Alternatively, the reducing atmosphere can be obtained by introducing gaseous reducing species into the sintering.

[0075] It should be noted that decomposition of CuH and sintering can be performed immediately after application of the formulation, or at any time thereafter. The sintering process can include heating of the patterned surface using a flasher with a heat lamp (xenon, NIR, etc.), a UV lamp, a laser, hot air, an oven, or any other suitable means of heat treatment.

[0076] Sintering can be selective. Selective sintering refers to sintering of selected portions of a pattern, where desired portions of the pattern are sintered and other portions are not sintered. Such selective sintering can be obtained, for example, by exposing the printed pattern to a radiation source (e.g., infrared or near infrared) through a suitable masking mask. The mask can be removably disposed on the printed pattern prior to exposure to the radiation source, or it can be disposed between the radiation source and the patterned surface. Additionally, selective sintering can also be obtained by laser scanning or other suitable means.

[0077] As described above, in the sintering process, the printed pattern is heated to a high temperature over a prescribed period, during which one or more processes occur. That is, if the temperature rises, CuH decomposes, the reactivity of copper with the phosphorus-containing compound increases (thus forming further CuH) and / or the phosphorus-containing compound can decompose. These processes are extremely exothermic, causing a local extreme and sharp temperature rise within the printed pattern.

[0078] Further, in order to achieve the exothermic effect and local heating as a result of chemical reactions, it is desirable that sintering be able to be performed at low temperatures, i.e. in the lower sintering temperature range described in the present specification.

[0079] Examples

[0080] The following shows examples of the present application, but the present application is not limited by the following examples. Note that, hereinafter, compounding ratios and the like are on a mass basis unless otherwise specified.

[0081] Each component was mixed in a manner to become the composition (content, mass %) shown in Tables 1 to 3 below, to prepare a conductive composition.

[0082] • Bisphenol-type epoxy resin (A1): Bisphenol A-type epoxy resin, epoxy equivalent = 270 g / eq

[0083] • Bisphenol-type epoxy resin (A2): Bisphenol F-type epoxy resin, epoxy equivalent = 226 g / eq

[0084] • Glycidyl amine-type epoxy resin: Glycidyl amine-type epoxy resin, epoxy equivalent = 124 g / eq

[0085] • (Meth)acrylic acid-type resin (B): Polymer of isobutyl methacrylate, weight average molecular weight = 17,000

[0086] • Polymer particles (C1): Average particle diameter = 100 nm, butadiene rubber polymer particles having a core-shell structure (core layer: polybutadiene rubber, shell layer: polymer of vinyl-based monomer)

[0087] • Polymer particles (C2): Average particle diameter = 100 nm, styrene butadiene rubber polymer particles having a core-shell structure (core layer: styrene butadiene rubber, shell layer: polymer of vinyl-based monomer)

[0088] • Copper particles (D): Average particle diameter = 100 nm

[0089] • Silver particles (E): Average particle diameter = 150 nm, spherical

[0090] • Phosphorus-containing compound (F): Hypophosphorous acid

[0091] • Copper hydride (G): CuH

[0092] Solvent (H1): 3-Methoxy-3-methylbutylacetic acid ester

[0093] Solvent (H2): Diethylene glycol monobutyl ether

[0094] The conductivity and adhesion of the obtained conductive compositions were evaluated, and the results are shown in Tables 1-3. The evaluation methods are as follows.

[0095] <Electrical conductivity>

[0096] The conductive compositions of each embodiment and comparative example were tested using a 420-mesh Tetoron plate and a polyurethane scraper, as shown in the figure. Figure 1 The polyimide film 10, measuring 100 mm in length, 65 mm in width, and 50 μm in thickness, was coated as shown. After drying in an air oven at 85°C for 2 minutes, it was pressed at a surface pressure of 1 MPa and a temperature of 200°C for 1 minute to obtain a sample with five cured specimens 11, each 70 mm long and 2 mm wide. The resistivity (R, Ω) of each cured specimen 11 was measured using a precision measuring instrument, and the average value was calculated. Additionally, the thickness of the cured specimen 11 was measured using a micrometer, and the thickness was determined from the sample cross-sectional area (S, cm²). 2 The volume resistivity (Ω·cm) is calculated using the following formula (1) based on the sample length (L, cm) and the sample length (1). If the volume resistivity is 2.5 × 10⁻⁶... -5 If the conductivity is below Ω·cm, it is considered to have excellent conductivity.

[0097] Volume resistivity = (sample cross-sectional area (S) / sample length (L)) × resistance value (R) ... (1)

[0098] <Seamlessness: Cross-cut Test>

[0099] The conductive compositions of each embodiment and comparative example were applied using a 420-mesh Tetoron plate and a polyurethane scraper to a prepared polyimide film measuring 60 mm long × 60 mm wide on a sheet measuring 100 mm long × 65 mm wide × 50 μm thick. After drying in an air oven at 85°C for 2 minutes, the film was pressed at a surface pressure of 1 MPa and a temperature of 200°C for 1 minute to obtain a sample with cured conductive composition. The obtained samples were evaluated using a cross-cut test according to ASTM D 3359. Defects were also evaluated, with "P" indicating no defects and "F" indicating defects. Samples without defects and with an evaluation score of 4B or higher according to ASTM D 3359 were considered to have excellent adhesion.

[0100] [Table 1]

[0101]

[0102] [Table 2]

[0103]

[0104] [Table 3]

[0105]

[0106] From the results shown in Tables 1 to 3, it is found that the conductive property and the adhesion of Examples 1 to 7 are excellent.

[0107] Comparative Example 1 is an example in which the bisphenol-type epoxy resin (A) and the polymer particles containing polybutadiene rubber (C) are not contained, and Comparative Example 2 is an example in which the content ratio of them is less than the lower limit value, and the adhesion is poor.

[0108] Comparative Example 3 is an example in which the content ratio of the bisphenol-type epoxy resin (A) is less than the lower limit value, and the adhesion is poor.

[0109] Comparative Example 4 is an example in which the (meth)acrylic resin (B) is not contained, and the adhesion is poor.

[0110] Comparative Examples 5 and 6 are examples in which the content ratio of the polymer particles containing polybutadiene rubber (C) exceeds the upper limit value, and the conductive property is poor.

[0111] Comparative Example 7 is an example in which the polymer particles containing styrene butadiene rubber are contained instead of the polymer particles containing polybutadiene rubber (C), and the adhesion is poor.

[0112] Comparative Example 8 is an example in which the content ratio of the silver particles (E) is less than the lower limit value, and the adhesion is poor.

[0113] Comparative Example 9 is an example in which the glycerol amine-type epoxy resin is compounded instead of the bisphenol-type epoxy resin (A), and the polymer particles containing polybutadiene rubber (C) are not contained, and the conductive property is poor.

[0114] Comparative Example 10 is an example in which the content ratio of the silver particles (E) and the content ratio of the (meth)acrylic resin (B) exceed the upper limit value, and the adhesion is poor.

[0115] Comparative Example 11 is an example in which the (A) component, the (B) component, the (C) component, and the (E) component are not contained, and the adhesion is poor.

[0116] Explanation of Reference Numerals

[0117] 10... polyimide film

[0118] 11... cured product of conductive composition

Claims

1. A conductive composition comprising: (A) Bisphenol type epoxy resin 1.005~1.74% by mass (B) A weight-average molecular weight of 1000 or more and less than 400,000% (meth)acrylic resin, comprising 0.015% by mass and less than 0.08% by mass. (C) Polymer particles containing polybutadiene rubber, 0.5~0.86% by mass (D) Copper particles with an average particle size of 2-500 nm, 5-95% by mass (E) 0.9–4.8% by mass of silver particles with an average particle size of 2–500 nm. (F) Phosphorus-containing compounds 0.001~20% by mass (G)CuH 0.0001~10% by mass, and (H) Solvent 0.1~90 by mass.

2. The conductive composition according to claim 1, wherein, The polymer particles (C) have a core-shell structure comprising a core layer and a shell layer. The core layer contains polybutadiene rubber. The shell is composed of a polymer of vinyl monomers.

3. The conductive composition according to claim 1 or 2, wherein, The ratio of copper particles (D) to silver particles (E), i.e. (D) / (E) by mass, is 15.0 to 45.

0.

4. The conductive composition according to any one of claims 1 to 3, wherein, The total content of copper particles (D) and silver particles (E) is 11.6 to 83.8% by mass.

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