JPWO2012118061A1 - Conductive composition - Google Patents

Abstract

Provided is a conductive composition that satisfies both cost reduction and good adhesiveness and expression of conductivity. (A) A volume average particle diameter D50 selected from the group consisting of silver-coated ceramic particles, silver-coated glass particles and silver-coated aluminum particles and measured by a laser light scattering method is 1 to 10 μm, and a scanning electron microscope The average thickness T measured by observation is 0.3 to 10 μm, the flaky silver-coated particles having an aspect ratio T / D50 of 0.3 to 1.0, (B) a thermosetting resin, and ( C) A conductive composition containing a curing agent, and a die bonding agent comprising the conductive composition.

Description

  The present invention relates to a conductive composition useful as a circuit pattern forming or die bonding agent.

  In the fields of mobile phones, personal computers, in-vehicle electronic components, etc., conductive compositions are used as bonding materials for forming circuit patterns and bonding semiconductor elements such as ICs and LSIs to lead frames or substrates. For example, the conductive circuit can be formed by applying a conductive composition on a substrate by screen printing or the like and then thermally curing the conductive composition. Further, the bonding between the semiconductor element and the lead frame or the substrate can be performed by applying a conductive composition to a predetermined part of the lead frame or the substrate, mounting the semiconductor element, and thermally curing the semiconductor element.

  In general, a conductive composition is one that develops conductivity by blending silver particles, but in recent years, while blending cheaper nickel particles and silver plating particles, it also has adhesiveness and conductivity. In view of the above, there is a demand for an electrically conductive composition that can provide a cured film. In order to meet this demand, conductive compositions containing silver-coated particles have been proposed (see Patent Documents 1 to 3).

JP 2009-256539 A JP 2006-260818 A JP 2007-242397 A

  However, the conductive composition of Patent Document 1 requires the use of an organometallic complex containing titanium and / or zirconium, and cannot sufficiently contribute to cost reduction. In addition, the conductive compositions of Patent Documents 2 and 3 use a thermoplastic resin such as a polyester resin having a molecular weight of 3000 or more and / or a modified polyester resin, and soften at a high temperature (260 ° C.). In addition, it becomes difficult to maintain reliability in reflow after moisture absorption. Furthermore, since flake powder having an average particle size / thickness of 2 or more and a high degree of flaming is used, when used for bonding a chip and a substrate, a plurality of flakes overlap to obtain vertical conduction, and consequently The contact resistance is high, and unlike silver, electricity passes through the periphery of the core material, so the conduction path is long, and the resistance value of vertical conduction is generally high. Furthermore, flake powder having a high average particle size / thickness of 2 or more and having a high degree of flaming has a large specific surface area. In order to uniformly coat with silver, it is necessary to increase the coating rate of silver, thus reducing the cost effectively. It will not be expected.

  This invention is made | formed in view of the said situation, Comprising: It aims at providing the electrically conductive composition which satisfies both cost reduction and favorable adhesiveness and expression of electroconductivity.

  As a result of extensive research, the present inventors have determined that the conductive composition is a flaky silver having a specific shape selected from the group consisting of silver-coated ceramic particles, silver-coated glass particles, and silver-coated aluminum particles. It has been discovered that blending the coated particles results in a cured film that is sufficient in terms of adhesion and conductivity, thus completing the present invention. In the present invention, since relatively inexpensive silver-coated particles are used, the cost can be reduced at the same time.

That is, the present invention
(A) A volume average particle diameter D50 selected from the group consisting of silver-coated ceramic particles, silver-coated glass particles and silver-coated aluminum particles and measured by a laser light scattering method is 1 to 10 μm, and a scanning electron microscope Flake-shaped silver-coated particles having an average thickness T measured by observation of 0.3 to 10 μm and an aspect ratio T / D50 of 0.3 to 1.0 (B) thermosetting resin, and (C ) It relates to a conductive composition containing a curing agent.

  ADVANTAGE OF THE INVENTION According to this invention, the electrically conductive composition which satisfies both cost reduction and favorable adhesiveness and expression of electroconductivity is provided.

It is the schematic of the sample used for the measurement of the specific resistance of an Example. It is the schematic of the sample etc. which are used for the measurement of the contact resistance of an Example. It is a SEM photograph of silver covering particle 1 used in an example.

  The conductive composition of the present invention is selected from the group consisting of (A) silver-coated ceramic particles, silver-coated glass particles, and silver-coated aluminum particles, and has a volume average particle diameter D50 measured by a laser light scattering method of 1 The average thickness T measured by observation with a scanning electron microscope is 0.3 to 10 μm, and the flaky silver-coated particles having an aspect ratio T / D50 of 0.3 to 1.0 are included. . The flaky silver-coated particles of the component (A) may be used alone or in combination of two or more.

  The core of the flaky silver-coated particles (A) is made of ceramic, glass or aluminum. Examples of ceramics include alumina, silicon carbide, silicon nitride, barium titanate, boron nitride, ferrite, steatite, zinc oxide, and zirconia. Freedom to obtain, freedom to control particle size and shape, and cost In particular, alumina is preferable.

  The flaky silver-coated particles (A) have a volume average particle diameter D50 measured by a laser light scattering method of 1 to 10 μm. When D50 is in this range, the workability of the conductive composition is good. For example, even in dispensing using a nozzle having an inner diameter of 100 to 200 μm, it is possible to discharge continuously without causing clogging of the nozzle. Become. Further, in the bonding between the semiconductor chip and the substrate, the film thickness of the conductive composition is often set to 20 to 30 μm, but the film thickness is increased due to the presence of the component (A), and the tilt of the chip is generated. This can also be avoided. D50 is a glass-coated particle with 2 cups of microspatella, taken in a 300 ml beaker, put 50 ml of 0.5% sodium sulfosuccinate dioctyl ester solution, and dispersed with an ultrasonic homogenizer for 10 minutes. (A Coulter LS230 (manufactured by Beckman Coulter)) The average value of 50% cumulative diameter is D50.

  (A) D50 of the flaky silver coating particle of a component is 1-10 micrometers, Preferably it is 3-8 micrometers.

  The flaky silver-coated particles (A) have an average thickness T measured by observation with a scanning electron microscope of 0.3 to 10 μm. When T is in this range, the workability of the conductive composition is good, and it is also possible to avoid the inconvenience that the chip is inclined due to the component (A) in joining the semiconductor chip and the substrate. The average thickness is 2 g of silver-coated particles, 5 g of epoxy resin (Epoxy Resin 20-8130-032 (manufactured by BUEHLER)) and 1 g of epoxy resin curing agent (EPOXY HARDENER 20-8132-008 (manufactured by BUEHLER)) in a 25 mm diameter clear cup. Take out and mix well using a spatula, let stand at room temperature for 12 hours, then remove the cured resin from the clear cup, perform surface processing with a microtome, and after carbon deposition, a field emission scanning electron microscope (manufactured by JEOL) JSM-7500F) is photographed at a magnification of 1000 times or 2000 times, the shortest side passing through the center is measured as the thickness of the silver coating, and the average value of 50 measured numbers is defined as the average thickness T.

  T of the (A) component flaky silver-coated particles is 0.3 to 10 μm, preferably 1 to 8 μm.

  The flaky silver-coated particles (A) have an aspect ratio T / D50 of 0.3 to 1.0. When the aspect ratio T / D50 is within this range, when the semiconductor chip and the substrate are joined, the semiconductor chip and the substrate are more conductive than the one having a higher degree of fragmentation (that is, the T / D50 is less than 0.3). The number of silver-coated particles can be reduced, thereby making it possible to reduce the contact resistance between the silver-coated particles. In addition, the one with a high degree of fragmentation has a long conduction path because electricity passes around the core material, whereas the silver-coated fine particles of the present invention require a short conduction path, thereby reducing the resistance value of vertical conduction. Is possible. In addition, it is expected to improve fluidity when the market share is higher than those with a high degree of fragmentation, and to improve workability such as improved dispensing performance. T / D50 is preferably 0.3 to 1.0, more preferably 0.4 to 1.0.

  The flaky silver-coated particles of component (A) have a maximum particle size of 40 μm from the viewpoint of workability (especially suppression of nozzle clogging during dispensing) and prevention of tip tilting in bonding between the semiconductor chip and the substrate. The following is preferable. The maximum particle size is a value measured with a light scattering analysis type particle size distribution measuring device. The maximum particle size is more preferably 35 μm or less, and further preferably 30 μm or less.

  The flaky silver-coated particles of the component (A) are preferably 10 to 60% by mass of the total weight of the silver-coated particles, more preferably from the viewpoint of silver coverage to the core material and conductivity. Is 20-50 mass%, More preferably, it is 20-40 mass%. The weight of the silver coating layer can be calculated from the weight of the silver coating particles and the core material measured by dissolving the silver coating layer in nitric acid and removing silver.

  The flaky silver-coated particles of the component (A) are preferably provided with a uniform silver coating layer, the silver coating layer is thick, and the specific gravity of the entire particle, and hence the specific gravity of the conductive composition, is increased. The thickness of the silver coating layer is preferably 50 to 300 nm from the viewpoint of avoiding a decrease in efficiency by reducing the volume when the conductive composition is applied with the same weight and obtaining stable conductivity. is there. The thickness of the silver coating layer is more preferably 50 to 200 nm, still more preferably 80 to 200 nm, and particularly preferably 80 to 150 nm. The thickness of the silver coating layer can be measured by preparing a sample similar to the average thickness T and using a field emission scanning electron microscope (JSM-7500F manufactured by JEOL) at a magnification of 10,000 to 30,000 times.

  The flaky silver-coated particles of the component (A) can be obtained by coating the ceramic, glass, and aluminum particles serving as the core with silver by a method such as electroless plating, sparring, or vapor deposition.

  The flaky silver-coated particles (A) are preferably those that have been surface-treated with a fatty acid or a salt thereof, or a coupling agent from the viewpoint of stability when formed into a paste.

  Examples of fatty acids include propionic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, acrylic acid, oleic acid, linoleic acid, arachidonic acid, epoxy resin, phenolic resin, acrylate resin, From the viewpoint of compatibility with isocyanate resin and maleimide resin, wettability, and reactivity to resin, oleic acid and stearic acid are preferred. Examples of fatty acid salts include metal salts of the above fatty acids such as lithium, sodium, potassium, barium, magnesium, calcium, aluminum, iron, cobalt, manganese, lead, zinc, tin, strontium, zirconium, silver, copper, and epoxy. From the viewpoint of compatibility with resins, phenolic resins, acrylate resins, isocyanate resins, and maleimide resins, wettability, and reactivity to resins, sodium salts are preferred.

  Examples of the surface treatment method using a fatty acid or a fatty acid salt include a method of dissolving a fatty acid or a fatty acid salt in an optionally heated alcohol, adding silver-coated particles thereto, and stirring the mixture for a certain period of time.

  Examples of coupling agents include silane coupling agents, titanate coupling agents, aluminum coupling agents, etc., compatibility with epoxy resins, phenol resins, acrylate resins, isocyanate resins, maleimide resins, wettability, resins From the viewpoint of reactivity to silane, a silane coupling agent and a titanate coupling agent are preferable.

  As a surface treatment method using a coupling agent, a method in which silver-coated particles are sprayed onto an agitator where the particles are being agitated, the coupling agent is dissolved in alcohol, and silver-coated particles are added thereto and stirred. There is a method of performing and processing.

  The conductive composition of the present invention contains (B) a thermosetting resin. (B) The thermosetting resin of a component is not specifically limited, For example, an epoxy resin, an acrylic resin, a silicone resin, a urethane resin, a maleimide resin etc. are mentioned. A thermosetting resin may be individual or may use multiple types together.

  The thermosetting resin as component (B) is preferably an epoxy resin from the viewpoint of adhesiveness, curability and heat resistance required for the die bonding agent. The epoxy resin is preferably liquid at normal temperature, but even if it is solid at normal temperature, it can be diluted with another liquid epoxy resin or diluent and used in liquid form. Specific examples of epoxy resins include bisphenol A type epoxy resins, brominated bisphenol A type epoxy resins, bisphenol F type epoxy resins, biphenyl type epoxy resins, novolac type epoxy resins, alicyclic epoxy resins, and naphthalene type epoxy resins. , Ether-based or polyether-based epoxy resins (for example, polyoxypropylene-modified epoxy resins such as polyoxypropylene bisphenol A diglycidyl ether), oxirane ring-containing polybutadiene, diglycidyl esterified modified products of dimer acid with epichlorohydrin, epoxy groups A polybutadiene compound having a molecular weight, a silicone epoxy copolymer resin, an aminophenol type epoxy resin (for example, N, N-bis (2,3-epoxypropyl) -4- (2,3-epoxypropylene) Piruokishi) aniline), and the like.

  In particular, the liquid epoxy resin has a bisphenol A type epoxy resin having an average molecular weight of about 400 or less; a branched polyfunctional bisphenol A type epoxy resin such as p-glycidyloxyphenyldimethyltrisbisphenol A diglycidyl ether; Bisphenol F type epoxy resin; phenol novolak type epoxy resin having an average molecular weight of about 570 or less; vinyl (3,4-cyclohexene) dioxide, 3,4-epoxycyclohexylcarboxylic acid (3,4-epoxycyclohexyl) methyl, adipine Cycloaliphatic epoxies such as bis (3,4-epoxy-6-methylcyclohexylmethyl) acid, 2- (3,4-epoxycyclohexyl) 5,1-spiro (3,4-epoxycyclohexyl) -m-dioxane Resin; 3, 3 ', Biphenyl type epoxy resin such as 5,5'-tetramethyl-4,4'-diglycidyloxybiphenyl; diglycidyl hexahydrophthalate, diglycidyl 3-methylhexahydrophthalate, diglycidyl neodecanoate glycidyl ester of hexahydroterephthalate Glycidyl ester type epoxy resins such as: diglycidyl aniline, diglycidyl toluidine, triglycidyl-p-aminophenol, tetraglycidyl-m-xylylenediamine, tetraglycidyl bis (aminomethyl) cyclohexane; And hydantoin type epoxy resins such as 1,3-diglycidyl-5-methyl-5-ethylhydantoin; naphthalene ring-containing epoxy resins. Moreover, an epoxy resin having a silicone skeleton such as 1,3-bis (3-glycidoxypropyl) -1,1,3,3-tetramethyldisiloxane can also be used. Furthermore, (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, butanediol glycidyl ether, neopentyl glycol diglycidyl ether, 1,4-cyclohexane dimethanol diglycidyl ether, 1,6-hexane Diol diglycidyl ether, p-tert-butylphenyl glycidyl ether, dicyclopentadiene dimethanol diglycidyl ether, glycidyl ether of trimethylolpropane, diglycidyl ether of polytetramethylene ether glycol, diglycidyl ether of dimer acid and polypropylene glycol Glycidyl ether, glycerin diglycidyl ether, neopentyl glycol diglycidyl ether, 1,4-phenyldi Diepoxide compounds such as ethanol diglycidyl ether; trimethylolpropane triglycidyl ether, also like triepoxide compounds such as glycerin triglycidyl ether and the like.

  The epoxy resin can be used in combination with a solid or ultra-high viscosity epoxy resin at room temperature, and as such an epoxy resin, a high molecular weight bisphenol A type epoxy resin, a novolac epoxy resin, a tetrabromobisphenol A type epoxy resin. And dicyclopentadiene type epoxy resin, isocyanate-modified epoxy resin, fluorene type epoxy resin, biphenyl aralkyl epoxy resin and the like. These can be used in combination with an epoxy resin and / or a diluent that is liquid at room temperature to adjust fluidity.

  When using an epoxy resin that is solid or ultra-highly viscous at room temperature, low-viscosity epoxy resins such as (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, butanediol glycidyl ether, neopentyl glycol diester Glycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether, 1,6-hexanediol diglycidyl ether, p-tert-butylphenylglycidyl ether, dicyclopentadiene dimethanol diglycidyl ether, glycidyl ether of trimethylolpropane Diglycidyl ether of polytetramethylene ether glycol, diglycidyl ether of dimer acid and diglycidyl ether of polypropylene glycol, glycerin diglycol Jill ether, neopentyl glycol diglycidyl ether, a diepoxide compound such as 1,4-phenyl-dimethanol diglycidyl ether; trimethylolpropane triglycidyl ether, be combined with such triepoxide compounds such as glycerin triglycidyl ether preferable.

  Examples of acrylic resins include neopentyl glycol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol dimethacrylate, dimethylol-tricyclodecane dimethacrylate, trimethylolpropane triacrylate. Methacrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate, hydroxypivalate neopentyl glycol dimethacrylate, 2-methacryloyloxyethyl phosphate ester, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 2 -Methacryloyloxyethyl-succinic acid, glycerin dimethacrylate, 2-methacryloyloxyethyl-phthalic acid, -Butyrolactone methacrylate, 2-methyl-2-adamantyl methacrylate, 2-ethyl-2-adamantyl methacrylate, ethoxylated cyclohexanedimethanol dimethacrylate or acrylates thereof, 1,4-cyclohexanedimethanol monoacrylate, methoxydipropylene glycol acrylate, Neopentyl glycol acrylic acid benzoate, propylene oxide modified diacrylate of bisphenol A, pentaerythritol triacrylate and the like.

  Examples of silicone resins include epoxy-modified polysiloxane, alicyclic epoxy-modified polysiloxane, carbinol-modified polysiloxane, carboxyl-modified polysiloxane, monoamine-modified polysiloxane, diamine-modified polysiloxane, hydrogen-modified polysiloxane, mercapto-modified polysiloxane, Examples include methacryl-modified polysiloxane and diol-modified polysiloxane.

Examples of the urethane resin include isocyanate resins, isocyanate resins whose isocyanate groups are blocked with ε-caprolactam, epoxy-modified urethane resins, methacrylate-modified urethane resins, and acrylate-modified urethane resins.
As the maleimide resin, bismaleimide resin (4,4′-diphenylmethane bismaleimide, m-phenylene bismaleimide, bisphenol A type diphenyl ether bismaleimide, 3,3′-dimethyl-5,5′-diethyl 4,4′-diphenylmethane is used. Bismaleimide, 4-methyl-1,3-phenylenebismaleimide, 1,6-bismaleimide- (2,2,4-trimethyl) hexane), monomaleimide resin (N-phenylmaleimide, N-cyclohexylmaleimide, o- Methylphenylmaleimide, p-hydroxyphenylmaleimide, p-carboxyphenylmaleimide, N-dodecylmaleimide).

  The conductive composition of the present invention contains (C) a curing agent. A hardening | curing agent can be suitably selected with a combination with a thermosetting resin, for example, a phenol resin, an amine compound, an acid anhydride, a peroxide, a metal complex, an azo compound etc. are mentioned. A hardening | curing agent may be individual or may use multiple types together.

  Examples of the phenol resin include bisphenol F type phenol resin, allyl phenol resin, phenol novolac resin, cresol novolac resin, naphthol modified phenol resin, dicyclopentadiene modified phenol resin, p-xylene modified phenol resin and the like.

  Examples of amine compounds include aliphatic polyamines, aromatic amines, modified polyamines (eg, polyaminoamides, polyaminoimides, polyaminoesters, polyaminoureas, polyether-modified amines), tertiary amine compounds, and imidazole compounds (eg, 2 -Methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2,2-diamino- 6- [2′-methylimidazolyl- (1 ′)]-ethyl-s-triazine, etc.), hydrazide compounds, dicyanamide compounds, melamine compounds and the like.

  Examples of acid anhydrides include methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, alkylated tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylheimic acid anhydride, and alkenyl-substituted succinic acid. Examples include acid anhydride, methyl nadic acid anhydride, glutaric acid anhydride and the like. Among them, 2,4-diethylpentanedioic anhydride, 3,4-dimethyl-6- (2-methyl-1-propenyl) -1,2,3,6-tetrahydrophthalic anhydride, 1-isopropyl-4 -Methyl-bicyclo [2.2.2] oct-5-ene-2,3-dicarboxylic acid anhydride, norbornane-2,3-dicarboxylic acid anhydride, methylnorbornane-2,3-dicarboxylic acid anhydride, hydrogen Methyl nadic acid anhydride, succinic acid anhydride substituted with an alkenyl group, and diethyl glutaric acid anhydride.

  Peroxides include 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanate, t-butylperoxybenzoate, t-butylperoxyneodecanoate, cumylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, t-butylperoxybenzoate, dicumyl peroxide, di-t-butyl peroxide, di-t-hexyl peroxide, di (2- t-butylperoxyisopropyl) benzene, 2,2-di (4,4-di- (butylperoxy) cyclohexyl) propane, p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, 1,1,3,3 -Tetramethylbutyl hydroperoxide, cumene hydroperoxide, 1 1,1-di (t-butylperoxy) cyclohexane, cyclohexanone peroxide, 1,1-di (t-hexylperoxy) cyclohexane.

  Examples of the metal complex include alkyl acetoacetate aluminum diisopropylate, aluminum tris (acetylacetonate), aluminum acrylate, aluminum bisethylacetoacetate diisopropylate, and magnesium 2-ethylhexanoate.

  Examples of the azo compound include 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 1,1′-azobis (cyclohexane- 1-carbonitrile), 2,2′-azobis {2-methyl-N- [2- (1-hydroxybutyl)] propionamide}, 2,2′-azobis [2-methyl-N- (2-hydroxy) Ethyl) propionamide], 2,2′-azobis [N- (2-propenyl) -2-methylpropionamide], 2,2′-azobis (N-cyclohexyl-2-methylpropionamide, 2,2′- And azobis [2- (2-imidazolin-2-yl) propane.

  When the conductive composition is used as a die bonding agent, suppression of bleed, good high temperature strength, suppression of decrease in high temperature strength after moisture absorption, and low water absorption are desired. In particular, the occurrence of bleed may induce peeling of the molding agent and the lead frame, which is important from the viewpoint of package reliability. From these viewpoints, as the component (B), an epoxy resin, an acrylic resin, and as the component (C), a combination of a phenol resin, an amine compound, and a peroxide is preferable.

  When (A) component, (B) component, and (C) component make these total 100 mass parts, (A) component shall be 40-80 mass parts from the point of electroconductivity and an elasticity modulus. Is more preferable, More preferably, it is 50-75 mass parts, More preferably, it is 50-65 mass parts. (B) It is preferable that it is 10-58 mass parts from the point of the fluidity | liquidity at the time of dispensing, bleeding, adhesive strength, and a water absorption rate, More preferably, it is 22-42 mass parts. The component (C) is preferably 2 to 10 parts by mass, more preferably 3 to 8 parts by mass from the viewpoint of voids, bleed, curability, and adhesive strength.

  You may mix | blend electrically conductive particles other than (A) component with the electrically conductive composition of this invention. The total amount of the conductive particles other than the component (A) is preferably 50% by mass or less, more preferably 30% in total in all the conductive particles (the silver-coated particles of the component (A) and the conductive particles other than the component (A)). Most preferably, only the silver-coated particles of component (A) are used as the conductive particles. As the conductive particles other than the component (A), spherical silver-coated ceramic particles, silver-coated glass particles, and silver-coated aluminum particles can be used. The core of the spherical silver-coated particles is preferably made of ceramic, glass or aluminum. Examples of ceramics include alumina, silicon carbide, silicon nitride, barium titanate, boron nitride, ferrite, steatite, zinc oxide, and zirconia. Freedom to obtain, freedom to control particle size and shape, and cost From this point, alumina is particularly preferable. The spherical silver-coated particles preferably have a volume average particle diameter D50 measured by a laser light scattering method of 1 to 20 μm, more preferably 2 to 15 μm. The spherical silver-coated particles are preferably 10 to 50% by mass of the total weight of the silver-coated particles having a spherical silver coating layer, more preferably, from the viewpoint of silver coverage on the core material and conductivity. 15 to 40% by mass. Spherical silver-coated particles preferably have a uniform silver coating layer, and the thickness of the silver coating layer increases, and the specific gravity of the entire particle, and hence the specific gravity of the conductive composition, increases. The thickness is preferably 50 to 300 nm from the viewpoint of avoiding a decrease in efficiency caused by reducing the volume when an object is applied with the same weight and obtaining stable conductivity. The thickness of the silver coating layer is more preferably 50 to 200 nm, still more preferably 70 to 150 nm.

  As the conductive particles other than the component (A), silver particles, copper particles, nickel particles, palladium particles, indium particles, tin particles, zinc particles, bismuth particles, or alloys thereof can also be used. The shape is not particularly limited.

  You may mix | blend a solvent with the electroconductive composition of this invention. The solvent is not particularly limited, and examples thereof include alcohol solvents such as ethylene glycol, propylene glycol, dihydroterpineol; toluene, xylene, ethylbenzene, diethylbenzene, isopropylbenzene, amylbenzene, p-cymene, tetralin, and petroleum aromatic hydrocarbons. Aromatic hydrocarbon solvents such as mixtures; Terpene alcohols such as terpineol, linalool, geraniol, citronellol; ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n- Butyl ether, propylene glycol mono-tert-butyl ether, diethylene glycol monoethyl ether, die Ether alcohol solvents such as tylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether; ketone solvents such as methyl isobutyl ketone; and ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether Examples thereof include ester solvents such as acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate, and water. A solvent may be individual or may use multiple types together.

  Furthermore, the conductive composition of the present invention includes an inorganic filler (for example, fumed silica, calcium carbonate, talc, etc.) and a coupling agent (for example, γ-glycerin) within the range that does not impair the predetermined effects of the present invention. Silane coupling agents such as Sidoxypropyltrimethoxysilane, Titanate coupling agents such as Tetraoctylbis (ditridecylphosphite) titanate), Silane monomers (for example, tris (3- (trimethoxysilyl) propyl) isocyanurate ), Plasticizer (for example, copolymer such as carboxyl group-terminated polybutadiene-acrylonitrile, silicone rubber, silicone rubber powder, silicone resin powder, resin powder such as acrylic resin powder), flame retardant, antioxidant, antifoaming agent, etc. can do.

  The conductive composition of the present invention is composed of (A) component, (B) component and (C) component, and optionally optional components such as a solvent, for example, using a three roll, planetary mixer, or likai machine. By mixing, a paste-like conductive composition can be produced. In addition, the order which mixes said each component is arbitrary, may be mixed simultaneously and may be mixed sequentially.

  Next, after applying the conductive composition obtained as described above to a desired object (for example, a substrate or the like), a cured film can be formed by heating and thermosetting.

  The coating method is not particularly limited, and examples thereof include dispensing, jet dispensing, stencil printing, screen printing, pin transfer, and stamping.

  The heating temperature can be, for example, 120 to 200 ° C., more preferably 150 to 175 ° C., and the heating time can be, for example, 1 to 120 hours, preferably 30 to 60 hours. is there.

  A conductive circuit can be formed by applying the conductive composition of the present invention on a substrate (for example, a ceramic substrate such as LTCC or a glass / epoxy substrate) and then thermally curing it. The conductive composition of the present invention can also be used as a die bonding agent. For example, after applying the die bonding agent made of the conductive composition of the present invention to a predetermined part of a lead frame or a substrate (for example, Bare Cu lead frame, Ag plated Cu lead frame, PPF, Ag plated 42 alloy frame). The semiconductor element can be mounted and thermally cured to bond the lead frame or the substrate and the semiconductor element.

The cured film thus obtained exhibits sufficient conductivity (for example, a specific resistance value of 1 × 10 ⁻² Ω · cm or less). Moreover, the adhesiveness (adhesion strength, adhesion resistance value) between the substrates is also good.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

  Each component shown in Table 1 and 2 was mixed using 3 rolls, and each electrically conductive composition of an Example and a comparative example was prepared.

The characteristics of each conductive composition of Examples and Comparative Examples were measured. The results are shown in Tables 1 and 2.
[Measurement of resistivity]
Each conductive composition of Examples and Comparative Examples using an alumina substrate (120 mm × 20 mm, thickness 1.6 mm) and a stainless mask (200 mesh, resist 20 μm) so as to have a pattern as shown in FIG. The object was screen printed. Next, it heated for 30 minutes with the ventilation drying machine hold | maintained at 150 degreeC +/- 5 degreeC, and the sample which formed the cured film was obtained. The resistance value X (Ω) at both ends of the cured film of the sample was measured using a 4261ALCR meter (manufactured by YHP).
The thickness Z (μm) of the cured film 2 of the conductive composition on the alumina substrate 1 was measured using a surface roughness profile measuring machine Surfcom 590A (surface roughness profile measuring machine manufactured by Tokyo Seimitsu Co., Ltd.) (FIG. 1− 2).
The specific resistance value ρ (Ω · cm) was calculated by the following equation.
ρ = (0.1 / 7.1) × X × Z × 10 ⁻⁴ (Ω · cm)
The average value was calculated from the measured values of the two samples, and used as the specific resistance value.

[Contact resistance value]
Using a metal mask (thickness: 70 μm) on the 25.4 ± 0.1 mm square alumina substrate 4 (see FIG. 2-1) provided with an Ag thick film electrode 3 having a thickness of 7 to 15 μm, Each conductive composition 5 of Examples and Comparative Examples was screen-printed using a metal mask (thickness 70 μm) so as to have a pattern like 2-2. Screen printing was performed using a metal squeegee (squeegee pressure 100 kPa, squeegee 20 mm / s, substrate-mask gap 0 mm, squeegee angle 60 °, plate separation speed 0.05 mm / s).
An AgPd electrode 3216 type capacitor component (capacitor electrode 6) is mounted so as to be in contact with the conductive composition 5 (FIG. 2-3), and a load of 1.0 ± 0.5 N is uniformly applied to the component. A sample was obtained.
In a thermostatic bath, the conductive composition was cured under predetermined curing conditions (heated to 150 ° C. in 30 minutes and held at 150 ° C. for 30 minutes).
The resistance value between the conductor (substrate electrode) within 1 mm from the upper part of the sample capacitor electrode 6 and the coated portion of the conductive composition 5 was measured by a four-terminal method (see FIG. 2-4). The measured current value of the current source was 10 ± 0.5 mA.
The average value was calculated from the measured values of 8 samples and used as the value of contact resistance.

(Measurement of adhesive strength)
Each conductive composition was screen-printed on a Bare Cu lead frame using a screen mask capable of forming 10 patterns of 1.5 mm □ × 40 μmt.
Ten 2 mm square silicon chips were mounted so that the silicon surface was in contact with the conductive composition.
In a thermostatic bath, curing was performed under predetermined curing conditions (heating to 150 ° C. in 30 minutes and holding at 150 ° C. for 30 minutes).
The obtained sample was struck from the side surface using a strength tester MODEL-1605HTP (manufactured by Aiko Engineering Co., Ltd.), and the numerical value when the silicon chip was peeled was read. The measurement was performed at a normal speed (25 ± 5 ° C.) at a test speed of 12 ± 1 mm / min when protruding from the side.

[Viscosity change]
An E-type viscometer TVE-22H was used, and a rotor 3 ° cone R9.7 was used.
Each conductive composition of Examples and Comparative Examples was sucked up by 0.3 ml using a Terumo syringe and applied to the center of the cup of the viscometer. The cup was attached to a viscometer, kept at 25 ° C. using a thermostatic bath, and allowed to stand for 10 minutes. The viscosity after 3 minutes at 0.5 rpm was measured (V1).
Each conductive composition of Examples and Comparative Examples was filled in a syringe and then left for 24 hours in an environment of 25 ° C. and 50% humidity. 0.3 ml of each conductive composition was sucked up using a syringe and applied to the center of the viscometer cup. The cup was attached to a viscometer, kept at 25 ° C. using a thermostatic bath, and allowed to stand for 10 minutes. The viscosity after 3 minutes at 0.5 rpm was measured (V2).
The rate of change in viscosity was calculated by the following formula.
Viscosity change rate (%) = (V2−V1) / V1 × 100

[Measurement of D50]
D50 is a glass-coated particle with 2 cups of microspatella, taken in a 300 ml beaker, put 50 ml of 0.5% sodium sulfosuccinate dioctyl ester solution, and dispersed with an ultrasonic homogenizer for 10 minutes. (A Coulter LS230 (manufactured by Beckman Coulter)) The average value of 50% cumulative diameter is D50.

[Measurement of average thickness T]
The average thickness is 2 g of silver coated particles, 5 g of epoxy resin (Epoxy Resin 20-8130-032 (manufactured by BUEHLER)) and 1 g of epoxy resin curing agent (EPOXY HARDENER 20-8132-008 (manufactured by BUEHLER)) in a 25 mm diameter clear cup. Take out and mix well using a spatula, let stand at room temperature for 12 hours, then remove the cured resin from the clear cup, perform surface processing with a microtome, and after carbon deposition, a field emission scanning electron microscope (manufactured by JEOL) JSM-7500F) is photographed at a magnification of 1000 times or 2000 times, the shortest side passing through the center is measured as the thickness of the silver coating, and the average value of 50 measured numbers is defined as the average thickness T.

[Weight of silver coating layer]
It is a value calculated from the weight of the silver-coated particles and the core material measured by dissolving the silver-coated layer in nitric acid and removing silver.

[Thickness of silver coating layer]
It is a value obtained by preparing a sample similar to the average thickness T, and measuring it at a magnification of 10,000 to 30,000 times with a field emission scanning electron microscope (JSM-7500F manufactured by JEOL).

The resins, curing agents and other components in Tables 1 and 2 are as follows.
Resin 1: Bisphenol F type epoxy resin Bisphenol F type epoxy resin (epoxy equivalent: 160 to 175)
Resin 2: Aminophenol type epoxy resin N, N-bis (2,3-epoxypropyl) -4- (2,3-epoxypropyloxy) aniline resin 3: PO modified epoxy resin Polyoxypropylene bisphenol A diglycidyl ether ( Epoxy equivalent 250-270)
Resin 4: Bismaleimide resin 1,6-Bismaleimide- (2,2,4-trimethyl) hexane curing agent 1: Polyoxypropylenediamine H ₂ N—SH (CH ₃ ) CH ₂ [OCH ₂ CH (CH ₃ ) ] XNH ₂
x = 33.1, active hydrogen equivalent: 514
Filler 1: Fumed silica Polydimethylsiloxane-treated fumed silica Volume-based average particle size: 0.25 μm

  FIG. 3A is an SEM photograph at a magnification of 5000 times of the silver-coated particles 1, and FIG. 3-2 is a graph illustrating the measurement of the average thickness. It is a SEM photograph of the section of hardened material.

From Table 1, all of Examples 1 to 6 using the flaky silver-coated particles of the present invention had small specific resistance values and contact resistance values, and were excellent in adhesive strength. Among these, Examples 3 to 6 using silver particles treated with oleic acid had little change in viscosity and were excellent in the stability of the conductive composition.
On the other hand, Comparative Example 1 using silver-coated particles having a small aspect ratio was inferior in specific resistance value and contact resistance value.
From Examples 7 to 9 in Table 2, even if the thermosetting resin system is changed, the flaky silver-coated particles of the present invention are effective, and even if the amount of silver-coated particles is changed, the flakes of the present invention It can be seen that the silver-coated particles are effective. Moreover, according to Examples 10 and 11 in Table 2, the silver-coated particles of the (A) component are based on 100 parts by mass in total of the conductive composition ((A) component, (B) component and (C) component). When 75 parts by mass was contained, the adhesive strength was slightly inferior. Further, according to Examples 14 and 15 of Table 2, the specific resistance value and the contact resistance value are small even when the silver coating layer of the component (A) is 50 to 60% by mass in the total weight of the silver-coated particles, The adhesive strength was also excellent. According to Example 15, when spherical silver-coated particles having an aspect ratio T / D50 of 1.0 were used, a tendency to be slightly inferior in terms of contact resistance was observed.

  ADVANTAGE OF THE INVENTION According to this invention, the electrically conductive composition which satisfies both cost reduction and favorable adhesiveness and expression of electroconductivity is provided. The conductive composition of the present invention is useful as a conductive circuit formation and die bonding agent.

Claims (9)

(A) A volume average particle diameter D50 selected from the group consisting of silver-coated ceramic particles, silver-coated glass particles and silver-coated aluminum particles and measured by a laser light scattering method is 1 to 10 μm, and a scanning electron microscope Flaky silver-coated particles having an average thickness T measured by observation of 0.3 to 10 μm and an aspect ratio T / D50 of 0.3 to 1.0,
(B) A thermosetting resin, and (C) a conductive composition containing a curing agent.   The electrically conductive composition of Claim 1 whose weight of the silver coating layer in (A) component is 10-60 mass%.   The conductive composition according to claim 1 or 2, wherein the component (A) is a silver-coated particle surface-treated with a fatty acid or a salt thereof, or a coupling agent.   The electrically conductive composition according to claim 3, wherein the component (A) is silver-coated particles surface-treated with one or more selected from the group consisting of oleic acid, stearic acid, and a silane coupling agent.   When the total of component (A), component (B) and component (C) is 100 parts by mass, component (A) is 40 to 80 parts by mass, component (B) is 10 to 58 parts by mass, (C) The electrically conductive composition of any one of Claims 1-4 whose component is 2-10 mass parts.   The conductive composition according to any one of claims 1 to 5, further comprising spherical silver-coated particles selected from the group consisting of spherical silver-coated ceramic particles, silver-coated glass particles, and silver-coated aluminum particles. .   The conductive composition according to claim 1, wherein the component (B) is at least one selected from the group consisting of an epoxy resin, an acrylic resin, a silicone resin, a urethane resin, and a maleimide resin.   The component (C) is at least one selected from the group consisting of a phenol resin, an amine compound, an acid anhydride, a peroxide, a metal complex, and an azo compound. Conductive composition.   A die bonding agent comprising the conductive composition according to claim 1.