KR20230170641A - conductive composition - Google Patents

Abstract

The purpose of the present invention is to provide a conductive composition capable of forming a cured product that is flexible and has excellent conductivity and adhesiveness at a low temperature, and an electronic device using the same. The conductive composition of the present invention is characterized in that it contains polyol, polyamine, blocked isocyanate, and conductive particles I having an average particle diameter (D50) of 0.4 ㎛ or more and 2.0 ㎛ or less, and the conductive composition is cured at a low temperature. The cargo is flexible and also has high conductivity and adhesiveness.

Description

conductive composition

The present invention relates to flexible conductive compositions and electronic devices.

As the uses of electronic devices expand, the development of flexible hybrid electronics (hereinafter referred to as FHE) is being conducted. In FHE, semiconductor components such as chips and capacitors are mounted on wiring formed on a flexible substrate. Since semiconductor components are rigid and cannot be deformed, a flexible, low-elastic conductive adhesive that can maintain the connection of the components even when the substrate is deformed and can follow deformation is required for the connection between the semiconductor component and the wiring. .

FHE is a flexible substrate with inferior heat resistance compared to substrates used in existing electronic devices such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polypropylene (PP), and polyurethane (PU). There are cases where is used. Therefore, conductive adhesives for joining components also require adhesion at low temperatures depending on the heat resistance of the substrate.

In contrast, in Patent Document 1, for the purpose of providing a conductive adhesive with excellent conductivity and adhesive strength with suppressed thickening at room temperature, a liquid epoxy resin and a liquid phenoxy resin are combined with silver powder and/or silver-coated metal powder. , a technology for adding a fixed amount of a potential glutaric acid generating compound is disclosed.

Additionally, in Patent Document 2, a polyether polymer having a main chain having a repeating unit represented by the formula: -R ¹ -O- (wherein R ¹ is a hydrocarbon group having 1 to 10 carbon atoms) and a terminal group that is a hydrolyzable silyl group. A technology for a conductive adhesive having good flexibility and high conductivity is disclosed by combining and silver particles.

Patent Document 3 discloses a technology related to a conductive composition that has excellent tackiness before curing and maintains a small change in resistance during stretching after curing by combining polyol, blocked isocyanate, and a conductive filler with an aspect ratio of 2 or more.

In Patent Document 4, a conductive metal on which a metal oxide and a lubricant exist on the surface and an isocyanate component react during heat curing, so that the metal oxide and the lubricant are at least partially removed from the surface of the conductive metal, thereby increasing the conductivity of the conductive composition. The technology has been disclosed.

Patent Document 1: Japanese Patent No. 5200662 Patent Document 2: Japanese Patent Publication No. 2018-48286 Patent Document 3: Japanese Patent Publication No. 2020-150236 Patent Document 4: Japanese Patent No. 4467439

In this way, there is currently a demand for a flexible conductive adhesive that can follow the deformation of the substrate. However, conductive adhesives used in ordinary electronic devices, such as those in Patent Document 1, have excellent adhesion and conductivity, but have a problem in that they lack flexibility. On the other hand, the conductive adhesive described in Patent Document 2 is excellent in flexibility and resistivity, but has a problem in that the curing temperature is high. In addition, the conductive adhesives using block isocyanate as a curing agent described in Patent Document 3 or Patent Document 4 are capable of curing at low temperatures and have excellent conductivity, but their flexibility and adhesiveness have not been sufficiently studied.

The present inventors conducted extensive research in order to develop a conductive composition for obtaining a cured material that is flexible and has high conductivity and adhesion at a low curing temperature, and as a result, polyol, polyamine, and blocked isocyanate as binders and specific conductive particles were used. It was discovered that by combining them, a cured product that was flexible and had excellent conductivity and adhesiveness could be obtained, leading to the following invention.

That is, the present invention has the following configuration.

[1] A conductive composition comprising polyol, polyamine, blocked isocyanate, and conductive particles, wherein the conductive particles include at least particles I having an average particle diameter (D50) of 0.4 μm or more and 2.0 μm or less.

[2] The conductive composition according to [1], wherein the particles I are silver.

[3] The conductive composition according to [1] or [2], wherein the conductive particles further include particles II having an average particle diameter (D50) of 5.0 μm or more and 15.0 μm or less.

[4] The conductive composition according to [3], wherein the particles II are silver.

[5] The conductive composition according to any one of [1] to [4], wherein the polyamine has an active hydrogen equivalent of 80 to 200 g/eq.

[6] The conductivity according to any one of [1] to [5], wherein the mixing ratio (polyol/polyamine) of the polyol and the polyamine is 7/3 to 2/8 based on the amount of active hydrogen group. Composition.

[7] The conductive composition according to any one of [1] to [6], wherein the solvent content is less than 10% by mass based on the total mass of the conductive composition.

[8] A cured product of the conductive composition according to any one of [1] to [7].

[9] An electronic device comprising a substrate having wiring, electronic components, and a cured product of the conductive composition described in [8] interposed between the electronic components and wiring.

[10] The electronic device according to [9], wherein the substrate is a stretchable and/or bendable substrate.

According to the present invention, in addition to polyol and blocked isocyanate, polyamine and conductive particles having a D50 of 0.4 μm or more and 2.0 μm or less are characterized. By combining polyamine and the above-mentioned conductive particles, the adhesion between the conductive particles and the binder interface is improved, so the adhesive strength can be improved while maintaining the flexibility of the resulting cured product. Additionally, because the conductive particles easily form a network, the conductivity of the resulting cured product can be improved.

1 is a schematic diagram showing a cross section of an electronic device using the conductive composition of the present invention.

[Conductive composition]

The conductive composition according to this embodiment is composed of polyol, polyamine, blocked isocyanate, and conductive particles.

Examples of polyols in the present invention include polyether polyol, polyester polyol, polycarbonate polyol, polyurethane polyol, polybutadiene polyol, polyisoprene polyol, polycaprolactone polyol, and castor oil-based polyol. These may be used individually or in combination of two or more types.

Examples of the polyether polyol include aromatic polyether polyol, aromatic/aliphatic copolymer polyether polyol, aliphatic polyether polyol, and alicyclic polyether polyol.

Examples of the polyester polyol include aromatic polyester polyol, aromatic/aliphatic copolymer polyester polyol, aliphatic polyester polyol, and cycloaliphatic polyester polyol. Among these, aliphatic polyester polyol is preferable from the viewpoint of flexibility. Examples of aliphatic polyester polyols include aliphatic polyols such as ethylene glycol, propylene glycol, butanediol, pentanediol, 3-methyl-1,5-pentanediol, hexanediol, heptanediol, decanediol, cyclohexanedimethanol, and caprolactonediol. Examples include those reacted with alcohol and aliphatic polyhydric carboxylic acids such as succinic acid, adipic acid, sebacic acid, fumaric acid, suberic acid, azelaic acid, and 1,10-decamethylenedicarboxylic acid as essential raw materials. It is possible to use a commercially available product. Specific examples of commercial products of aliphatic polyester polyol include, for example, ODX-2420, ODX-2692 (manufactured by DIC Kuraray Co., Ltd.), Kurarepolyol P-510, P-1010, P-2050 (manufactured by DIC Kuraray Co., Ltd.), Nit. Foran 4009, 164, 141 (manufactured by Tosoh Corporation), etc. can be mentioned.

Examples of the polycarbonate polyol include aromatic polycarbonate polyol, aromatic/aliphatic copolymerization polycarbonate polyol, aliphatic polycarbonate polyol, and cycloaliphatic polycarbonate polyol.

Examples of the polyurethane polyol include aromatic polyurethane polyol, aromatic/aliphatic copolymerization polyurethane polyol, aliphatic polyurethane polyol, and cycloaliphatic polyurethane polyol.

Among them, polyester polyol is preferable because it is easy to improve curability and conductivity. It is also preferable to combine polyester polyol with polyols other than polyester polyol. Among the polyols, the proportion of polyester polyol is preferably 60% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 98% by mass or more. It is % by mass or more, and may also be 100 % by mass.

The hydroxyl value of the polyol is not particularly limited, but is preferably 50 to 300 KOHmg/g, and more preferably 100 to 250 KOHmg/g from the viewpoint of improving conductivity and adhesiveness.

The weight average molecular weight of the polyol is not particularly limited, but is preferably 400 to 2000 g/mol, and more preferably 450 to 1500 g/mol, from the viewpoint of improving conductivity and adhesiveness.

Apart from the polyol component, a compound having one hydroxyl group may be further included as long as it does not impair performance. Examples of compounds having one hydroxyl group include aliphatic saturated alcohols such as 1-pentanol, octanol, and cyclohexaneethanol; Aliphatic unsaturated alcohols such as 10-undecen-1-ol; Aromatic alcohols such as 2-phenylethyl alcohol and benzyl alcohol; Additionally, their derivatives, denatured products, etc. can be mentioned. The content of the compound having one hydroxyl group is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less, based on 100 parts by mass of polyol.

Examples of polyamines used in the present invention include aliphatic polyamines such as chain aliphatic polyamines, cyclic aliphatic polyamines, and aromatic ring aliphatic polyamines, cycloaliphatic polyamines, and aromatic polyamines, as well as derivatives and modified products thereof. These may be used individually or in combination of two or more types. Examples of the derivatives include alkyl derivatives of polyamines, and examples of the modified products include epoxy adducts of polyamines, Mannich reactants, Michael reactants, thiourea reactants, polyamideamines that are polymerized fatty acid and/or carboxylic acid reactants, etc. can be mentioned.

The aliphatic polyamine is a compound in which at least one amino group is bonded to a chain aliphatic hydrocarbon having 1 or more carbon atoms (however, excluding compounds having a structure in which an amino group is directly bonded to an aromatic ring), and the chain aliphatic hydrocarbon has an aliphatic ring or an aromatic ring. It is okay to combine them. Compounds in which an amino group and an aliphatic ring are bonded to a chain aliphatic hydrocarbon are particularly called cyclic aliphatic polyamines, and compounds in which an amino group and an aromatic ring are bonded to a chain aliphatic hydrocarbon are especially called aromatic ring aliphatic polyamines. Specific examples of aliphatic polyamines include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, norbornanediamine, m-xylenediamine, p-xylenediamine, and isophoronediamine.

The alicyclic polyamine is a compound in which all amino groups are directly bonded to an aliphatic ring, and specific examples include cyclohexanediamine.

The aromatic polyamine is a compound in which at least one amino group is directly bonded to an aromatic ring, and specifically, metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, diaminodiphenyl ether, ethylenedianiline, diethyl Toluenediamine, aminobenzylamine, bisaniline, etc. can be mentioned.

Among them, aliphatic polyamine or its modified form is preferable because it is easy to improve flexibility. Specific examples of commercially available aliphatic polyamines or their modified forms include, for example, Fujicure FXJ-8027-H, FXJ-859-C, FXD-821-F, Tomide 280-C, and TXE-524 (manufactured by T&K TOKA Corporation). , Jeffamine D-400 (manufactured by Tomoe Kogyo Co., Ltd.), Jer Cure FL11, SA1 (manufactured by Mitsubishi Chemical Co., Ltd.), etc.

Additionally, it is also preferable to combine an aliphatic polyamine or a modified form thereof with a polyamine other than the aliphatic polyamine or a modified form thereof. Among the polyamines, the proportion of aliphatic polyamine or its modified form is preferably 60% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, particularly preferably 95% by mass or more, most preferably It is preferably 98% by mass or more, and may also be 100% by mass.

The active hydrogen equivalent of the polyamine is preferably 80 g/eq or more, and more preferably 85 g/eq or more, from the viewpoint of coexistence of flexibility, adhesiveness, and conductivity. Moreover, from the viewpoint of ease of availability and improved adhesion, 200 g/eq or less is preferable, and 190 g/eq or less is more preferable. The active hydrogen equivalent of the polyamine is preferably 80 to 200 g/eq, and more preferably 85 to 190 g/eq. In this specification, “the active hydrogen equivalent of polyamine” refers to the molecular weight per equivalent of an active hydrogen group in the polyamine, and the active hydrogen group means an amino group having an active hydrogen group in the polyamine.

The amine titer of the polyamine is not particularly limited, but is preferably 150 to 350 KOH mg/g, and more preferably 160 to 330 KOH mg/g. If the amine titer is within that range, the increase in viscosity of the conductive composition is suppressed and handling becomes easy.

The viscosity of the polyamine is not particularly limited, but from the viewpoint of making handling easier, it is preferably 2000 mPa·s or less, and more preferably 800 mPa·s or less.

The mixing ratio (polyol/polyamine) of polyol and polyamine in the present invention is preferably 2/8 to 7/3, and more preferably 3/7 to 6/4, based on the amount of active hydrogen group. By increasing the ratio of polyamine, the adhesiveness and conductivity of the obtained cured product can be improved, and by increasing the ratio of polyol, the flexibility of the obtained cured product can be improved, so by keeping the mixing ratio of polyol and polyamine within the above range. , the balance of flexibility, adhesiveness, and conductivity of the cured product becomes better.

Additionally, the mixing ratio (polyol/polyamine) is calculated based on the following formula.

Mixing ratio (polyol/polyamine) = total amount of active hydrogen substances contained in polyol / total amount of active hydrogen substances contained in polyamine

The above-mentioned “total amount of active hydrogen group substance contained in polyamine” means the total mass (unit: g) of polyamine contained in the conductive composition divided by the active hydrogen equivalent of the polyamine (g/eq). In the case of a mixture of two or more types of polyamines, the mass (unit: g) of each compound can be obtained by dividing it by the active hydrogen equivalent (g/eq) of the polyamine and summing them.

In addition, “total amount of active hydrogen group substance contained in polyol” means the total weight (unit: g) of polyol contained in the conductive composition divided by the active hydrogen equivalent (g/eq) of the polyol. When two or more polyols are a mixture, it can be obtained by dividing the mass (unit: g) of each compound by the active hydrogen equivalent (g/eq) of the polyol and adding them up. In addition, the above-mentioned “active hydrogen equivalent of polyol” refers to the molecular weight per equivalent of an active hydrogen group in the polyol, and the active hydrogen group means a hydroxy group (-OH) possessed by the polyol.

The total content of polyol and polyamine in the present invention is not particularly limited, but is preferably 1% by mass or more and 50% by mass or less, and more preferably 2% by mass or more and 30% by mass or less, relative to the total amount of the conductive composition. , most preferably 3% by mass or more and 15% by mass or less. By keeping the amounts of polyol and polyamine within the range, the balance between flexibility and conductivity becomes better.

The isocyanate constituting the block isocyanate used in the present invention is preferably a compound (polyisocyanate) having a plurality of isocyanate groups in the molecule. Examples of the polyisocyanate include aliphatic polyisocyanates such as hexamethylene diisocyanate (hereinafter referred to as HDI) and isophorone diisocyanate (IPDI); Aromatic polyisocyanates such as diphenylmethane diisocyanate (MDI) and tolylene diisocyanate (TDI); Modified forms of these polyisocyanates, such as isocyanurate form, adduct form, and biuret form, etc. are mentioned, and from the viewpoint of improving flexibility, aliphatic polyisocyanate or modified form of aliphatic polyisocyanate is preferable.

Each of the isocyanates may be monomers, but it is preferable that they are multimers of each isocyanate or modified forms of the multimer, such as an isocyanurate form, an adduct form, or a biuret form.

The most preferable isocyanate is a polymer of aliphatic polyisocyanate such as a polymer of HDI, or a modified form thereof.

Examples of the blocking agent constituting the block isocyanate include phenol-based, oxime-based, alcohol-based, lactam-based, activated methylene-based, and pyrazole-based blocking agents. Among them, active methylene-based blocking agents and pyrazole-based blocking agents are preferable because they can lower the reaction temperature. One type of blocking agent may be included individually, or two or more types may be included. From the viewpoint of curing properties and storage stability, it is preferable to contain both active methylene-based and pyrazole-based blocking agents.

Examples of the active methylene-based blocking agent include malonic acid diesters, and specifically include dimethyl malonate, diethyl malonate, dibutyl malonate, bis(2-ethylhexyl) malonate, methylbutyl malonate, and dimalonate. Dialkyl malonate such as ethylhexyl; Diaryl malonate such as diphenyl malonate; etc. can be mentioned.

Examples of the pyrazole-based blocking agent include pyrazole, 3,5-dimethylpyrazole, 3-methylpyrazole, and 4-nitro-3,5-dimethylpyrazole.

Examples of the phenol-based blocking agent include phenol, cresol, ethylphenol, and styrenated phenol.

Examples of the oxime-based blocking agent include formamidoxime, acetaldoxime, acetone oxime, methyl ethyl ketoxime, methyl isobutyl ketoxime, and cyclohexanone oxime.

Examples of the alcohol-based blocking agent include methanol, ethanol, 2-propanol, n-butanol, sec-butanol, tert-butanol, 2-ethyl-1-hexanol, 2-methoxyethanol, 2-ethoxyethanol, 2 -Butoxyethanol, etc. can be mentioned.

Examples of the lactam-based blocking agent include ε-caprolactam, δ-valerolactam, and γ-butyrolactam.

As the block isocyanate, commercial products can be used. Examples of the commercial products include Duranate SBN-70D, SBB-70P, TPA-B80E (manufactured by Asahi Kasei Corporation), Desmodur BL3272MPA, BL3475BA/SN, BL3575MPA/SN (Covestro (manufactured by Baxenden), Trixene BI7960, BI7982, BI7991, and BI7992 (manufactured by Baxenden).

In the present invention, the mixing ratio (NCO group/active hydrogen group) of all the active hydrogen groups of the polyol and polyamine and the isocyanate group of the blocked isocyanate is not particularly limited, but is preferably 0.7 or more and less than 2.0, based on the amount of material, and is 0.8 or more. , it is more preferable that it is 1.5 or less. Within that range, better adhesiveness can be achieved while maintaining the flexibility of the cured product.

The conductive composition in the present invention may further contain a catalyst within a range that does not impair performance. The catalyst is not particularly limited, and examples include organic tin compounds, organic bismuth metal compounds, and tertiary amine compounds. The content of the catalyst is preferably 1.0% by mass or less, more preferably 0.1% by mass or less, based on the total amount of the conductive composition.

The conductive particles used in the present invention include particles I (hereinafter referred to as conductive particles I) having an average particle diameter (D50) of 0.4 μm or more and 2.0 μm or less. When the D50 of the conductive particles I is less than 0.4 μm, the elastic modulus of the cured product increases and cracks occur during deformation, and when the D50 of the conductive particles I is greater than 2.0 μm, the adhesive strength decreases. The average particle diameter (D50) of the conductive particles I is more preferably 0.5 μm or more and 1.5 μm or less, and most preferably 0.6 μm or more and 1.2 μm or less.

The shape of the conductive particles I is not particularly limited, but examples include scales (also called flakes), irregularly shaped aggregates, spherical shapes, and lumps. Among them, the flaky shape is preferable from the viewpoint of preventing a decrease in viscosity during heating.

The content of the conductive particles I in the present invention is not particularly limited, but is preferably 25% by mass or more and 95% by mass or less, and more preferably 30% by mass or more and 90% by mass or less, relative to the total amount of the conductive composition. By keeping the amount of conductive particles within that range, the balance between flexibility and conductivity becomes better.

The conductive particles in the present invention may further include particles II (hereinafter referred to as conductive particles II) having an average particle diameter (D50) of 5 μm or more and 15 μm or less. When the conductive particles contain conductive particles II, flexibility is further improved. The average particle diameter (D50) of the conductive particles II is preferably 6 μm or more and less than 12 μm.

In addition, the average particle size (D50) in the present invention represents the particle size when the cumulative volume basis of the particle size measured by laser diffraction is 50%.

The shape of the conductive particles II is not particularly limited, but examples include scales, irregularly shaped aggregates, spherical shapes, and lumps, and among these, lumps are preferable.

Examples of conductive particles I and conductive particles II include silver, copper, gold, platinum, palladium, aluminum, nickel, indium, bismuth, zinc, lead, tin, and carbon black. These may be used individually or in combination of two or more types. In addition, the materials of electroconductive particle I and electroconductive particle II may be the same or different. Among these, from the viewpoint of conductivity, it is preferable to use silver particles as at least one of the conductive particles I and II (preferably the conductive particles I), and to use the silver particles alone as at least the conductive particles I. It is more preferable to use silver particles alone for both conductive particles I and conductive particles II.

The total content of conductive particles I and conductive particles II in the conductive particles is preferably 80 mass% or more, more preferably 90 mass% or more, further preferably 95 mass% or more, especially preferably 98 mass%. % or more, and may be 100% by mass.

The total content of conductive particles in the present invention is not particularly limited, but is preferably 50% by mass or more and 95% by mass or less, and more preferably 60% by mass or more and 90% by mass or less, relative to the total amount of the conductive composition. By keeping the amount of conductive particles within that range, the balance between flexibility and conductivity becomes better.

When the conductive particles of the present invention contain conductive particles II, the mixing ratio of the conductive particles I and conductive particles II (conductive particles I/conductive particles II) is not particularly limited, but is preferably 95/5 to 50/50. , it is more preferable that it is 90/10 to 70/30. By keeping the mixing ratio of conductive particles I and conductive particles II within the range, a cured product that maintains conductivity and adhesiveness and is flexible can be obtained.

The total content of polyol, polyamine, blocked isocyanate, and conductive particles is preferably 70% by mass or more, more preferably 80% by mass or more, and still more preferably 90% by mass or more, based on the total amount of the conductive composition. It may be more than mass%, and may be 100 mass%.

The conductive composition in the present invention may not contain a solvent or may contain a solvent. The solvent content in the conductive composition is preferably less than 10% by mass, more preferably less than 5% by mass, and may be 0% by mass or more than 1% by mass. By setting the solvent content within the above range, the generation of bubbles when forming the cured product can be suppressed, and the resulting cured product can be thickened into a film.

The type of solvent is not particularly limited, but examples include ethyl acetate, butyl acetate, solvent naphtha, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate.

The conductive composition in the present invention further contains a thermoplastic resin, an inorganic filler, a conductive additive, a pigment, a dye, a dispersant, an antifoaming agent, a leveling agent, a thixotropic imparting agent, a reactive diluent, a flame retardant, an antioxidant, an ultraviolet absorber, and a hydrolysis inhibitor. , tackifiers, plasticizers, etc. can be added. The blending amount of the imparting agent is preferably 10% by mass or less, more preferably 3% by mass or less, and still more preferably 1% by mass or less, based on the total amount of the conductive composition.

The conductive composition in the present invention is made by mixing polyol and polyamine as binder components, block isocyanate, conductive particles, and optionally used components in a dissolver, three-roll mill, self-rotating mixer, attritor, ball mill, or sand mill. It can be obtained by mixing and dispersing using a disperser such as.

Since the conductive composition in the present invention is capable of achieving both flexibility, adhesiveness, and conductivity, it is suitably used as a conductive adhesive (preferably a conductive adhesive used in flexible hybrid electronics). By applying or printing the conductive composition of the present invention to a substrate and curing it, it can be used as a solder substitute for mounting electronic components. The process for applying onto the substrate is not particularly limited, but examples include screen printing, stamping, dispensing, and squeegee printing. Additionally, by curing the conductive composition, it can be used for joining or mounting semiconductor device chip components, connecting circuits, adhering crystal oscillators or piezoelectric elements, or sealing packages.

The heating temperature during curing is appropriately determined depending on the reaction temperature of the active hydrogen group and blocked isocyanate group and the heat resistance of the substrate used. The heating temperature may be, for example, 80 to 150°C or 100 to 130°C. The heating time is not particularly limited, but is, for example, about 10 to 120 minutes, and is preferably about 30 to 60 minutes.

From the viewpoint of flexibility, the cured product formed using the conductive composition of the present invention preferably has a storage modulus of 50 MPa or more and 600 MPa or less at 25°C, as measured using a viscoelasticity measuring device, and is 150 MPa or more. It is more preferable that it is more than MPa and less than 500 MPa.

From the viewpoint of conductivity, the cured product preferably has a specific resistance of less than 2.0×10 ^-4 Ω·cm, and more preferably less than 1.0×10 ^-4 Ω·cm.

From the viewpoint of adhesiveness, the cured product preferably has a shear adhesive force of 2.0 MPa or more, and more preferably 2.5 MPa or more when an oxygen-free copper plate is used as the adherend.

The electronic device according to the present embodiment has a substrate having wiring and electronic components, and a cured product of the conductive composition is interposed between the electronic components and wiring. As a result, the wiring formed on the substrate and the electronic components can be physically and electrically connected. 1 is a schematic cross-sectional view showing an example of the electronic device, and the electronic device includes a substrate 10, wiring 20 formed on the surface of the substrate 10, and electronic components 30, and the wiring A cured product 40 of the conductive composition is interposed between 20 and the electronic component 30 (more precisely, the electrode 31 formed on the electronic component 30). The electronic component 30 and the wiring 20 are electrically connected by the cured material 40.

The substrate in the electronic device according to this embodiment may be a substrate capable of stretching and/or bending. Since the cured product of the conductive composition has flexibility, it can follow the stretching and bending of the substrate, and the occurrence of peeling and cracks at the connection between electronic components and wiring is suppressed. Therefore, the electronic device according to this embodiment has high connection reliability even if it is flexible.

The stretchable and/or bendable substrate used in the present invention is not particularly limited, but includes fiber structures, resin films, rubber, etc. As a fiber structure. Examples include knitted fabrics, fabrics, non-woven fabrics, and paper. Examples of the resin film include polyethylene terephthalate, polyvinyl chloride, polyethylene, polypropylene, polycarbonate, polyethylene naphthalate, polyurethane, polyimide, polymethyl methacrylate, and silicone. Examples of the rubber include nitrile-containing rubbers such as urethane rubber, acrylic rubber, silicone rubber, butadiene rubber, nitrile rubber, and hydrogenated nitrile rubber, isoprene rubber, sulfide rubber, styrene-butadiene rubber, butyl rubber, and ethylene propylene rubber.

This application claims the benefit of priority based on Japanese Patent Application No. 2021-066506 filed on April 9, 2021. The entire content of the specification of Japanese Patent Application No. 2021-066506 filed on April 9, 2021 is incorporated herein by reference.

Example

Below, examples will be presented to explain the present invention in more detail and detail. In addition, the operations and evaluation results in the examples were measured by the following methods.

<Elastic modulus>

The conductive composition was applied on a Teflon (registered trademark) film using an applicator with a gap of 200 μm. After curing by heating at 130°C for 60 minutes using a hot air dryer, it was cooled to room temperature. After that, the coating film was cut to 4 mm x 300 mm and peeled from the Teflon (registered trademark) film to obtain a test piece for evaluating the elastic modulus. The test piece was set in a viscosity measuring device (DVA-200 manufactured by IT Keisoku Seiko Co., Ltd.), strain: 0.1%, frequency: 10 Hz, temperature increase rate: 4°C/min, measurement temperature range: -10°C to 100°C. By operating the device under these conditions, the storage modulus of elasticity at 25°C was determined.

<Resistivity>

The conductive composition was applied onto the PET film using an applicator with a 50 μm gap. After curing by heating at 130°C for 60 minutes using a hot air dryer, it was cooled to room temperature. After that, the coating film was cut into 10 mm x 35 mm to obtain a test piece for evaluation of specific resistance. The film thickness of the test piece was measured using a thickness gauge (SMD-565L manufactured by TECLOCK), and the sheet resistance of the test piece was measured using Loresta-GP (MCP-T610 manufactured by Mitsubishi Chemical Analytech). Measurements were made on four test pieces each, and the resistivity was calculated using the average value.

<Adhesiveness>

To evaluate the adhesion of the conductive composition, two oxygen-free copper plates (dimensions: 25 mm x 100 mm x 1 mm, material: C1020P, hardness: 1/2H) were used as the adherend. After washing the surface of the adherend with acetone, the conductive composition was applied to one copper plate to an area of 25 mm x 12.5 mm, and the other copper plate was bonded together. After curing by heating at 130°C for 60 minutes using a hot air dryer, it was cooled to room temperature. Adhesion was measured using a precision universal tester (AG-20kNXDplus manufactured by Shimadzu Seisakusho Co., Ltd.) in an environment of 23°C and RH 50% at a tensile speed of 10 mm/min in the shear direction.

Examples 1 to 4, Comparative Examples 1 to 2

<Example of manufacturing conductive composition>

Various components were added according to the mixing ratio in Table 1, and after preliminary mixing, they were dispersed in a three-roll mill to form a paste, thereby obtaining a conductive composition. The evaluation results of the obtained conductive composition are shown in Table 1 below.

In addition, each component in Table 1 is as follows.

Polyol: Kuraray Corporation polyester polyol P-510 (active hydrogen equivalent: 250 g/eq, hydroxyl value: 224 KOHmg/g, weight average molecular weight: 500 g/mol)

Polyamine 1: T&K TOKA Co., Ltd. modified aliphatic polyamine FXJ-859-C (active hydrogen equivalent: 190 g/eq, amine value: 170 KOHmg/g, viscosity: 450 mPa·s)

Polyamine 2: T&K TOKA Co., Ltd. modified aliphatic polyamine FXD-821-F (active hydrogen equivalent: 85 g/eq, amine value: 300 KOHmg/g, viscosity: 65 mPa·s)

Isocyanate: Baxenden block isocyanate BI7992 (NCO: equivalent weight 456 g/eq)

Conductive particle 1: Metallo Technologies Japan Co., Ltd. flake silver P791-24 (D50: 0.7 ㎛)

Conductive particles 2: Metallo Technologies Japan Co., Ltd., bulk silver P318-41 (D50: 9.0 ㎛)

Conductive particle 3: Metallo Technologies Japan Co., Ltd., bulk silver P853-11 (D50: 8.0 ㎛)

Since Examples 1 to 4 contained polyamine and conductive particles of 0.4 μm≤D50≤2.0 μm in addition to polyol and blocked isocyanate, cured products that were flexible and had high conductivity and adhesiveness were obtained. From the comparison of Examples 1 and 2, it was found that reducing the mixing amount of polyamine to polyol resulted in a more flexible cured product. Furthermore, from the comparison of Examples 3 and 4, by mixing conductive particles of 5.0 μm≤D50≤15.0 μm with conductive particles of 0.4 μm≤D50≤2.0 μm, a flexible cured product that maintains conductivity and adhesiveness can be obtained. I knew that

Since Comparative Example 1 did not contain polyamine, it was flexible but had poor conductivity and adhesiveness. In Comparative Example 2, the adhesiveness was significantly reduced because it did not contain silver particles of 0.4 ㎛ ≤ D 50 ≤ 2.0 ㎛.

As shown above, the conductive composition of the present invention can form a cured product that is flexible and has excellent conductivity and adhesiveness at low temperatures, and is particularly suitable as a bonding material for wiring and electronic components formed on a flexible substrate.

10. Substrate
20. Wiring
30. Electronic components
31. Electrode
40. Cured product of conductive composition

Claims (10)

A conductive composition comprising polyol, polyamine, blocked isocyanate, and conductive particles, wherein the conductive particles include at least particles I having an average particle diameter (D50) of 0.4 μm or more and 2.0 μm or less. The conductive composition according to claim 1, wherein the particles I are silver. The conductive composition according to claim 1 or 2, wherein the conductive particles further include particles II having an average particle diameter (D50) of 5.0 μm or more and 15.0 μm or less. The conductive composition according to claim 3, wherein the particles II are silver. The conductive composition according to any one of claims 1 to 4, wherein the polyamine has an active hydrogen equivalent of 80 to 200 g/eq. The conductive composition according to any one of claims 1 to 5, wherein the mixing ratio (polyol/polyamine) of the polyol and the polyamine is 7/3 to 2/8 based on the amount of active hydrogen group. . The conductive composition according to any one of claims 1 to 6, wherein the solvent content is less than 10% by mass based on the total mass of the conductive composition. A cured product of the conductive composition according to any one of claims 1 to 7. An electronic device comprising a substrate having wiring, electronic components, and a cured product of the conductive composition according to claim 8 interposed between the electronic components and wiring. The electronic device according to claim 9, wherein the substrate is a flexible and/or bendable substrate.