JP2015162392A - Conductive paste, electric/electronic component, and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive paste which can be sintered by low-temperature heating and can give a solid excellent in electrical conductivity and thermal conductivity, an electric/electronic component which has an electrode obtained by bringing the conductive paste into contact with a noble metal and sintering it, and a method of manufacturing the electric/electronic component.SOLUTION: There are provided: the conductive paste which contains (A) a flaky silver powder having an average particle diameter of 2-20 μm, a tap density (TD) of 2.0-7.0 g/cm, and a carbon-containing compound content of 0.5 mass% or less, (B) silver nanoparticles having an average particle diameter of 10-500 nm, and (C) a thermosetting resin; the electric/electronic component having an external electrode or an internal electrode formed using the conductive paste; and the method of manufacturing the electric/electronic component.

Description

  The present invention contains, as main components, flaky silver powder, silver nanoparticles, and a thermosetting resin, and is a conductive paste excellent in workability, and highly reliable electric / electronic using the same. The present invention relates to a component and a manufacturing method thereof.

  There are capacitors and inductors as electrical / electronic components obtained by forming electrodes with conductive paste. For example, a solid electrolytic capacitor has a configuration in which a dielectric layer is formed on an anode body made of metal, and a semiconductor layer, a carbon layer, and a cathode layer are formed on the dielectric layer. Has a cathode layer formed of a conductive paste bonded and fixed to a cathode lead frame. The cathode layer functions as an electrical connection layer and a mechanical bonding layer with the cathode lead frame. In the inductor, a conductive paste is also used to maintain electrical connection with the internal copper core coil.

  As the conductive paste used as the electrode forming material or the conductive adhesive described above, for example, an epoxy resin or an acrylic resin is used as a base resin (binder resin), and a mixture of silver powder or the like is known. (For example, see Patent Documents 1 to 3). As the conductive inorganic filler, micron-sized silver powder is often used from the viewpoint of workability and cost. However, since a resin layer is interposed between the metal deposit and the conductive inorganic filler, the following measures are taken. Was planned.

  When conductive paste is used as the external electrode, the capacitor reduces the internal electrode and silver powder contacts by high filling of silver powder to reduce the resistance. Similarly, the inductor reduces the resistance by the same method as the internal copper core. Yes. However, in a reliability test assuming an external environment in use, since a thermosetting resin is interposed between the internal electrode in the capacitor and the copper core in the inductor, the resistance is deteriorated.

  In the conductive paste described above, spherical or flaky micron-sized silver powder is usually used. However, due to the recent increase in demand for lower resistance and higher reliability of electronic components, The conductive paste is not sufficiently effective and is difficult to apply.

JP-A-6-267784 JP 2002-97215 A International Publication No. 2009/98938

  In Patent Document 1, a thermosetting conductive paste in which a conductive resin such as silver is mixed with a binder resin, which is a thermosetting resin, is applied to the take-out surface of the internal electrode of the multilayer ceramic composite, and then thermoset at about 200 ° C. To form an external electrode substrate. However, since the curing temperature is low, the conductive powder such as silver in the thermosetting conductive paste and the internal electrode cannot be eutectic, and the designed electrical characteristics cannot be obtained and the reliability is sufficiently high. There is a problem that does not increase.

  On the other hand, in Patent Document 2, which is a high-temperature sintering type conductive paste, the conductive paste is fired at a high temperature of 500 ° C. to 1100 ° C., so that the resin is thermally decomposed and the metal powder is sintered. Time is required and productivity is a problem.

  Further, in Patent Document 3, a specific (tin silver) alloy powder must be used, and there is a problem that the formed electrode cannot obtain sufficient reliability.

  Further, when the conductive paste is used as the external electrode of the inductor, the resistance value may be deteriorated due to the oxidation of the internal copper core in the inductor, so that curing at 300 ° C. or lower has been desired. A product capable of curing at 300 ° C. or lower in a normal state that does not require ultrasonic vibration or pressurization has not been developed yet.

  Such a conductive paste for electric / electronic parts is generally applied by dip coating when applied to a terminal as an external electrode, but the surface of the dip tank is roughened during immersion, so that squeezing The conductive paste is flattened and continuously applied to the device by dip coating.

  However, with the conventional conductive powder used at this time (a combination of micron silver and silver nanoparticles), the viscosity gradually increases during the squeezing, and in some cases, the silver nanoparticles aggregate to increase productivity. There was a problem that affected.

  Furthermore, when the thixotropy ratio of the conductive paste is 5.0 or more, there is a problem in that cornering occurs at the bottom of the element during dip coating, resulting in poor appearance.

  Therefore, the present invention provides a conductive paste that can be sintered by low-temperature heating, and can obtain a solid material excellent in electrical conductivity and thermal conductivity, and an electrode obtained by sintering the conductive paste in contact with a noble metal. It is an object of the present invention to provide an electric / electronic component and a manufacturing method thereof.

  As a result of intensive studies, the present inventors have found that the above problems can be solved by using a specific filler in combination as the conductive inorganic filler, and have completed the present invention.

That is, the conductive paste of the present invention has (A) an average particle diameter of 2 to 20 μm, a tap density (TD) of 2.0 to 7.0 g / cm ³ , and a carbon-containing compound content of 0.5. It contains flaky silver powder having a mass% or less, (B) silver nanoparticles having an average particle diameter of 10 to 500 nm, and (C) a thermosetting resin.

  The method for producing an electric / electronic component of the present invention is characterized in that after the conductive paste is brought into contact with a noble metal, it is sintered at a low temperature at 100 to 300 ° C. to form an external electrode or an internal electrode.

The electrical / electronic component of the present invention is obtained by sintering the conductive paste in contact with a noble metal, and has an external volume resistivity of 1 × 10 ⁻⁵ Ω · cm or less after sintering. It has an electrode or an internal electrode.

  The conductive paste of the present invention can be sintered by low-temperature heating, and a solid material excellent in electrical conductivity and thermal conductivity can be obtained. Therefore, the electrical / electronic parts obtained using this conductive paste can be sufficiently sintered with a member whose adherend is a noble metal such as gold, silver, platinum, or copper by low-temperature heating to form a metal bond. Moreover, it has very excellent reliability in the moisture resistance test. Furthermore, the conductive paste of the present invention improves the continuous workability at the time of dip coating by using specific silver powder and silver nanoparticles, thereby efficiently forming electrodes of electrical / electronic components. Can be produced and has excellent mass production stability.

  Hereinafter, the present invention will be described in detail.

As described above, the conductive paste of the present invention has (A) an average particle diameter of 2 to 20 μm, a tap density (TD) of 2.0 to 7.0 g / cm ³ , and a content ratio of the carbon-containing compound. It contains flaky silver powder of 0.5% by mass or less, (B) silver nanoparticles having an average particle diameter of 10 to 500 nm, and (C) a thermosetting resin.

The flaky silver powder of component (A) in the present invention has an average particle size of 2 to 20 μm, a tap density (TD) of 2.0 to 7.0 g / cm ³ , and a carbon-containing compound content of 0.5. What is necessary is just mass% or less, and what is a flaky thing, for example, commercially available various silver powder can be used.

  The average particle size of the flaky silver powder of component (A) is 2 to 20 μm. When the average particle size is within this range, the shape retention of the conductive paste is good. If this average particle size is less than 2 μm, the thixotropy is high, and appearance defects during dip coating tend to occur. If it exceeds 20 μm, the sinterability is lowered and the conductivity and thermal conductivity may be impaired. . Furthermore, it is preferable that the average particle diameter of this (A) component flaky silver powder is 2.5-15 micrometers.

Moreover, the flaky silver powder of the component (A) has a tap density (TD) of 2.0 to 7.0 g / cm ³ . When the tap density is within this range, the volume resistivity of the cured product of the conductive paste can be kept low, the thixotropy is improved, and the occurrence of stringing at the time of applying the conductive paste is suppressed. The tap density (TD) is preferably 2.5 to 6.5 g / cm ³ .

In addition, although flaky silver powder can mix and use 2 or more types of silver powders from which average particle diameter or tap density (TD) differs, in that case, it is the said requirements and average particle | grains as the whole mixed flaky silver powder. It is only necessary that the diameter is 2 to 20 μm and the tap density (TD) satisfies 2.0 to 7.0 g / cm ³ .

Here, the average particle diameter of the silver powder is 50% of the cumulative volume in the particle size distribution measured using a laser diffraction particle size distribution measuring device (for example, product name: LA-500 manufactured by Horiba, Ltd.). The particle size (50% particle size D ₅₀ ). The tap density (TD) is measured as a mass (unit: g / cm ³ ) per unit volume of the powder in the container which is vibrated by a Tap-Pak Volumemeter.

  In addition, as the flaky silver powder of the component (A), a carbon-containing compound having a content of 0.5% by mass or less is used. By setting the content of the carbon-containing compound to 0.5% by mass or less, thickening of the conductive paste after squeegee coating can be suppressed.

  In the flaky silver powder of the component (A), in order to make the content of the carbon-containing compound 0.5% by mass or less, the content of the carbon-containing compound added mainly for the purpose of preventing aggregation of the flaky silver powder is This can be achieved by reducing the weight.

  Here, the carbon-containing compound is preferably a long-chain fatty acid or a long-chain fatty acid derivative. The long chain fatty acid may be either a saturated fatty acid or an unsaturated fatty acid, but is preferably a fatty acid having 8 or more carbon atoms from the viewpoint of preventing aggregation of the flaky silver powder. Further, the long chain fatty acid preferably has 8 to 30 carbon atoms, and more preferably 12 to 24 carbon atoms. Examples of the long chain fatty acid include myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, and the like. Examples of the long-chain fatty acid derivatives include the long-chain fatty acid derivatives described above, and examples include long-chain fatty acid metal salts, long-chain fatty acid esters, and long-chain fatty acid amides.

  Further, the flaky silver powder of the component (A) can be formed into a flaky shape to form a cured product having excellent sinterability with silver nanoparticles, and a cured product having a low resistance value can be obtained. Therefore, silver powder of spherical shape, spherical block shape, resinous shape or the like is not included. Here, the flake shape is a silver powder having a shape like a flaky thin plate or a flaky plate.

  Moreover, the silver nanoparticle of the (B) component in this invention is a silver particle whose average particle diameter is 10-500 nm. When the average particle size is within this range, the sinterability of the conductive paste is improved, and a low resistance value can be achieved. If the average particle size is less than 10 nm, the particles become unstable, and if it exceeds 500 nm, the sinterability may be hindered. The average particle diameter of the silver nanoparticles as the component (B) is preferably 20 to 400 nm.

  Here, the average particle diameter of the silver nanoparticles of the component (B) is an average particle diameter measured by a dynamic light scattering method (DLS) with a scattering particle size analyzer (Nikkiso Co., Ltd., Microtrac Series). is there.

  Moreover, as (C) thermosetting resin in this invention, if it is a thermosetting resin generally used as an adhesive agent, it can be used without being specifically limited. Among these, a liquid resin is preferable, and a resin that is liquid at room temperature (25 ° C.) is more preferable. Examples of the (C) thermosetting resin include cyanate resin, epoxy resin, radical polymerizable acrylic resin, maleimide resin, and the like.

  The cyanate resin is a compound having an —NCO group in the molecule, and forms a three-dimensional network structure by the reaction of the —NCO group by heating to be cured. Specifically, 1,3-dicyanatobenzene, 1,4-dicyanatobenzene, 1,3,5-tricyanatobenzene, 1,3-dicyanatonaphthalene, 1,4-dicyanatonaphthalene, 1, 6-dicyanatonaphthalene, 1,8-dicyanatonaphthalene, 2,6-dicyanatonaphthalene, 2,7-dicyanatonaphthalene, 1,3,6-tricyanatonaphthalene, 4,4'-dicyanatobiphenyl, bis (4-cyanatophenyl) methane, bis (3,5-dimethyl-4-cyanatophenyl) methane, 2,2-bis (4-cyanatophenyl) propane, 2,2-bis (3,5-dibromo -4-Cyanatophenyl) propane, bis (4-cyanatophenyl) ether, bis (4-cyanatophenyl) thioether, bis (4-cyanatophenyl) Examples of the polyfunctional cyanate resins include luphone, tris (4-cyanatophenyl) phosphite, tris (4-cyanatophenyl) phosphate, and cyanates obtained by reacting novolac resins with cyanogen halides. A prepolymer having a triazine ring formed by trimerizing a cyanate group can also be used. This prepolymer is obtained by polymerizing the above-mentioned polyfunctional cyanate resin monomer using, for example, an acid such as mineral acid or Lewis acid, a base such as sodium alcoholate or tertiary amine, or a salt such as sodium carbonate as a catalyst. It is done.

  As the curing accelerator for the cyanate resin, generally known ones can be used. Examples include organometallic complexes such as zinc octylate, tin octylate, cobalt naphthenate, zinc naphthenate and acetylacetone iron, metal salts such as aluminum chloride, tin chloride and zinc chloride, and amines such as triethylamine and dimethylbenzylamine. However, it is not limited to these. These curing accelerators can be used alone or in combination. In addition, the cyanate resin can be used in combination with other resins such as an epoxy resin, an oxetane resin, an acrylic resin, and a maleimide resin.

  The epoxy resin is a compound having one or more glycidyl groups in the molecule, and is a resin that forms a three-dimensional network structure by the reaction of the glycidyl groups by heating and cures. It is preferable that two or more glycidyl groups are contained in one molecule, but this is because sufficient cured product characteristics cannot be exhibited even if the glycidyl group is reacted with only one compound. Compounds containing two or more glycidyl groups per molecule include bisphenol compounds such as bisphenol A, bisphenol F, and biphenol or derivatives thereof, hydrogenated bisphenol A, hydrogenated bisphenol F, hydrogenated biphenol, cyclohexanediol, and cyclohexanedimethanol. Diols having an alicyclic structure such as cyclohexanediethanol or derivatives thereof, bifunctional ones obtained by epoxidizing aliphatic diols such as butanediol, hexanediol, octanediol, nonanediol, decanediol, or derivatives thereof, Hydroxyphenylmethane skeleton, trifunctional one having aminophenol skeleton, phenol novolac resin, cresol novolac resin, phenol aralkyl resin, biphenyla Examples include, but are not limited to, polyfunctional ones obtained by epoxidizing rualkyl resin, naphthol aralkyl resin, and the like, and the resin composition is paste-like or liquid at room temperature, either alone or as a mixture Those which are liquid at room temperature are preferred. It is also possible to use reactive diluents as is usual. Examples of the reactive diluent include monofunctional aromatic glycidyl ethers such as phenyl glycidyl ether and cresyl glycidyl ether, and aliphatic glycidyl ethers.

  At this time, a curing agent is used for the purpose of curing the epoxy resin. Examples of the curing agent for the epoxy resin include aliphatic amines, aromatic amines, dicyandiamide, dihydrazide compounds, acid anhydrides, and phenol resins. . Examples of the dihydrazide compound include carboxylic acid dihydrazides such as adipic acid dihydrazide, dodecanoic acid dihydrazide, isophthalic acid dihydrazide, p-oxybenzoic acid dihydrazide, and the acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, hexahydroanhydride. Examples thereof include phthalic acid, endomethylenetetrahydrophthalic anhydride, dodecenyl succinic anhydride, a reaction product of maleic anhydride and polybutadiene, and a copolymer of maleic anhydride and styrene.

  A phenol resin used as a curing agent for an epoxy resin is a compound having two or more phenolic hydroxyl groups in one molecule. In the case of a compound having one phenolic hydroxyl group in one molecule, a cross-linked structure may be taken. Therefore, the cured product characteristics deteriorate and cannot be used.

  The number of phenolic hydroxyl groups in one molecule can be used as long as it is 2 or more, but the number of phenolic hydroxyl groups is preferably 2 to 5. When the amount is larger than this, the molecular weight becomes too large, and the viscosity of the conductive paste becomes too high, which is not preferable. The number of phenolic hydroxyl groups in one molecule is more preferably 2 or 3.

  Such compounds include bisphenol F, bisphenol A, bisphenol S, tetramethyl bisphenol A, tetramethyl bisphenol F, tetramethyl bisphenol S, dihydroxy diphenyl ether, dihydroxy benzophenone, tetramethyl biphenol, ethylidene bisphenol, methyl ethylidene bis (methyl phenol). ), Bisphenols such as cyclohexylidene bisphenol and biphenol and derivatives thereof, trifunctional phenols such as tri (hydroxyphenyl) methane and tri (hydroxyphenyl) ethane, and phenols such as phenol novolac and cresol novolac A compound obtained by reacting formaldehyde with formaldehyde, which is mainly dinuclear or trinuclear and its derivatives Body and the like.

Furthermore, a curing accelerator can be blended in order to accelerate curing. Examples of epoxy resin curing accelerators include imidazoles, triphenylphosphine or tetraphenylphosphine and salts thereof, amine compounds such as diazabicycloundecene, and the like. Examples thereof include 2-methylimidazole, 2-ethylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl- 4,5-dihydroxy methyl imidazole, _2-C 11 _{H 23} -, imidazole compounds such as the adduct of 2-methylimidazole and 2,4-diamino-6-vinyl-triazine is preferably used. Particularly preferred is an imidazole compound having a melting point of 180 ° C. or higher. The epoxy resin is also preferably used in combination with a cyanate resin, an acrylic resin, or a maleimide resin.

  The radical polymerizable acrylic resin is a compound having a (meth) acryloyl group in the molecule, and is a resin that forms a three-dimensional network structure by the reaction of the (meth) acryloyl group and cures. It is preferable that one or more (meth) acryloyl groups are contained in the molecule. Particularly preferred acrylic resins are polyethers, polyesters, polycarbonates, poly (meth) acrylates having a molecular weight of 100 to 10,000 and compounds having a (meth) acrylic group.

  Here, as a polyether, what a C1-C6 organic group repeated via the ether bond is preferable, and what does not contain an aromatic ring is preferable. It can be obtained by reacting a polyether polyol with (meth) acrylic acid or a derivative thereof.

  The polyester is preferably a group in which an organic group having 1 to 6 carbon atoms is repeated via an ester bond, and preferably does not contain an aromatic ring. It can be obtained by reacting a polyester polyol with (meth) acrylic acid or a derivative thereof.

  As a polycarbonate, what a C1-C6 organic group repeated via the carbonate bond is preferable, and the thing which does not contain an aromatic ring is preferable. It can be obtained by reacting a polycarbonate polyol with (meth) acrylic acid or a derivative thereof.

  Examples of the poly (meth) acrylate include a copolymer of (meth) acrylic acid and (meth) acrylate or a copolymer of (meth) acrylate having a polar group and (meth) acrylate having no polar group. preferable. In the case of reacting these copolymers with a carboxyl group, it can be obtained by reacting with an acrylate having a hydroxyl group, and when reacting with a hydroxyl group, (meth) acrylic acid or a derivative thereof.

  If necessary, the following compounds can be used in combination. For example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxy Butyl (meth) acrylate, 1,2-cyclohexanediol mono (meth) acrylate, 1,3-cyclohexanediol mono (meth) acrylate, 1,4-cyclohexanediol mono (meth) acrylate, 1,2-cyclohexanedimethanol mono (Meth) acrylate, 1,3-cyclohexanedimethanol mono (meth) acrylate, 1,4-cyclohexanedimethanol mono (meth) acrylate, 1,2-cyclohexanediethanol mono (meth) acrylate 1,3-cyclohexanediethanol mono (meth) acrylate, 1,4-cyclohexanediethanol mono (meth) acrylate, glycerin mono (meth) acrylate, glycerin di (meth) acrylate, trimethylolpropane mono (meth) acrylate, tri (Meth) acrylate having a hydroxyl group such as methylolpropane di (meth) acrylate, pentaerythritol mono (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, neopentyl glycol mono (meth) acrylate, Examples thereof include (meth) acrylates having a carboxy group obtained by reacting these (meth) acrylates having a hydroxyl group with dicarboxylic acids or derivatives thereof. Examples of the dicarboxylic acid usable here include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, phthalic acid, and tetrahydrophthalic acid. Examples include acids, hexahydrophthalic acid, and derivatives thereof.

  In addition to the above, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tertiary butyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) Acrylate, tridecyl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, isoamyl (meth) acrylate, isostearyl (meth) acrylate, behenyl (meth) acrylate, 2-ethylhexyl (meth) acrylate , Other alkyl (meth) acrylates, cyclohexyl (meth) acrylate, tertiary butyl cyclohexyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, benzyl (meth) acrylate, Noxyethyl (meth) acrylate, isobornyl (meth) acrylate, glycidyl (meth) acrylate, trimethylolpropane tri (meth) acrylate, zinc mono (meth) acrylate, zinc di (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl ( (Meth) acrylate, neopentyl glycol (meth) acrylate, trifluoroethyl (meth) acrylate, 2,2,3,3-tetrafluoropropyl (meth) acrylate, 2,2,3,3,4,4-hexafluoro Butyl (meth) acrylate, perfluorooctyl (meth) acrylate, perfluorooctylethyl (meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, tetramethylene glycol di (meth) acrylate, methoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxypolyalkylene glycol mono (meth) Atalylate, Octoxy polyalkylene glycol mono (meth) acrylate, Lauroxy polyalkylene glycol mono (meth) acrylate, Stearoxy polyalkylene glycol mono (meth) acrylate, Allyloxy polyal Xylene glycol mono (meth) acrylate, nonylphenoxypolyalkylene glycol mono (meth) acrylate, acryloylmorpholine, hydroxyethylacrylamide, N, N′-methylenebis (meth) acrylamide, N, N′-ethylenebis (meth) acrylamide, 1,2-di (meth) acrylamide ethylene glycol, di (meth) acryloyloxymethyl tricyclodecane, N- (meth) acryloyloxyethylmaleimide, N- (meth) acryloyloxyethyl hexahydrophthalimide, N- (Meth) acryloyloxyethylphthalimide, n-vinyl-2-pyrrolidone, a styrene derivative, an α-methylstyrene derivative and the like can also be used.

  Here, in the polymerization reaction of the thermosetting resin, a polymerization initiator is generally used, but the polymerization initiator is preferably a thermal radical polymerization initiator, and is not particularly limited as long as it is a known thermal radical polymerization initiator. Can be used. In addition, as the thermal radical polymerization initiator, those having a decomposition temperature of 40 to 140 ° C. in a rapid heating test (decomposition start temperature when 1 g of a sample is placed on an electric heating plate and heated at 4 ° C./min). preferable. When the decomposition temperature is less than 40 ° C., the storage stability of the conductive paste at normal temperature is deteriorated, and when it exceeds 140 ° C., the curing time becomes extremely long. Specific examples of the thermal radical polymerization initiator satisfying such characteristics include methyl ethyl ketone peroxide, methylcyclohexanone peroxide, methyl acetoacetate peroxide, acetylacetone peroxide, 1,1-bis (t-butylperoxy) 3, 3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) cyclohexane, 1,1-bis (t-hexylperoxy) 3,3,5-trimethylcyclohexane, 1,1-bis (t- Butylperoxy) cyclohexane, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane, 1,1-bis (t-butylperoxy) cyclododecane, n-butyl-4, 4-bis (t-butylperoxy) valerate, 2,2-bis (t-butyl) -Oxy) butane, 1,1-bis (t-butylperoxy) -2-methylcyclohexane, t-butyl hydroperoxide, p-menthane hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide , T-hexyl hydroperoxide, dicumyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, α, α'-bis (t-butylperoxy) diisopropylbenzene, t -Butyl cumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne-3, isobutyryl peroxide, 3,5,5-trimethylhexa Noyl peroxide, octanoyl peroxide, lauroyl peroxide, cinnamic acid peroxide Xoxide, m-toluoyl peroxide, benzoyl peroxide, diisopropyl peroxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, di-3-methoxybutyl peroxydicarbonate, di-2-ethyl Hexyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, di (3-methyl-3-methoxybutyl) peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, α, α′-bis (neodecanoylperoxy) diisopropylbenzene, cumylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, 1-cyclohexyl-1-methylethylperoxy Neodecanoate, t-hexi Peroxyneodecanoate, t-butylperoxyneodecanoate, t-hexylperoxybivalate, t-butylperoxybivalate, 2,5-dimethyl-2,5-bis (2-ethylhexanoyl) Peroxy) hexane, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t-hexylperoxy 2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxymaleic acid, t-butylperoxylaurate, t-butyl Peroxy-3,5,5-trimethylhexanoate, t-butylperoxyisopropyl monocarbonate T-butylperoxy-2-ethylhexyl monocarbonate, 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane, t-butylperoxyacetate, t-hexylperoxybenzoate, t -Butylperoxy-m-toluoylbenzoate, t-butylperoxybenzoate, bis (t-butylperoxy) isobutarate, t-butylperoxyallyl monocarbonate, 3,3 ', 4,4'-tetra (t -Butylperoxycarbonyl) benzophenone and the like can be mentioned, but these can be used alone or in combination of two or more in order to control curability. The radical polymerizable acrylic resin is also preferably used in combination with a cyanate resin, an epoxy resin, or a maleimide resin.

  The maleimide resin is a compound that contains one or more maleimide groups in one molecule, and forms a three-dimensional network structure when the maleimide group reacts by heating, and is cured. For example, N, N ′-(4,4′-diphenylmethane) bismaleimide, bis (3-ethyl-5-methyl-4-maleimidophenyl) methane, 2,2-bis [4- (4-maleimidophenoxy) phenyl ] A bismaleimide resin such as propane may be mentioned. More preferred maleimide resins are compounds obtained by reaction of dimer acid diamine and maleic anhydride, and compounds obtained by reaction of maleimidated amino acids such as maleimide acetic acid and maleimide caproic acid with polyols. The maleimidated amino acid is obtained by reacting maleic anhydride with aminoacetic acid or aminocaproic acid. As the polyol, polyether polyol, polyester polyol, polycarbonate polyol, poly (meth) acrylate polyol is preferable, and an aromatic ring is formed. What does not contain is especially preferable.

  Since the maleimide group can react with an allyl group, the combined use with an allyl ester resin is also preferable. The allyl ester resin is preferably an aliphatic one, and particularly preferred is a compound obtained by transesterification of a cyclohexane diallyl ester and an aliphatic polyol. The number average molecular weight of the allyl ester compound is not particularly limited, but is preferably 500 to 10,000, and particularly preferably 500 to 8,000. When the number average molecular weight is within the above range, curing shrinkage can be particularly reduced, and deterioration of adhesion can be prevented. Moreover, combined use with cyanate resin, an epoxy resin, and an acrylic resin is also preferable.

The conductive paste of the present invention contains 40-94.5% by mass, preferably 55-90% by mass of the flaky silver powder of component (A) in the conductive paste, and 5 silver nanoparticles of component (B). -50 mass%, Preferably it contains 10-45 mass%, and contains 0.5-20 mass%, Preferably 1-15 mass% of thermosetting resin of (C) component.
Here, (A) component and (B) component are 50-95 mass% of (A) component and 5 (B) component with respect to the total amount [(A) component + (B) component]. It is preferable to contain -50 mass% from a viewpoint of resistance reduction, and it is more preferable to contain (A) component 55-90 mass% and (B) component 10-45 mass%.

  In the thermosetting resin of the present invention, in addition to each of the above components, a curing accelerator, a rubber, a silicone, and the like, which are generally blended in this type of composition within a range that does not impair the effects of the present invention. Agents, coupling agents, antifoaming agents, surfactants, colorants (pigments, dyes), various polymerization inhibitors, antioxidants, and other various additives can be blended as necessary. Each of these additives may be used alone or in combination of two or more.

  Such additives include silane coupling agents such as epoxy silane, mercapto silane, amino silane, alkyl silane, ureido silane, vinyl silane, sulfide silane, titanate coupling agent, aluminum coupling agent, aluminum / zirconium coupling agent. Coupling agents such as carbon black, colorants such as carbon black, solid stress reducing components such as silicone oil and silicone rubber, and inorganic ion exchangers such as hydrotalcite.

  The conductive paste of the present invention, after thoroughly mixing the above-described components (A) to (C), and additives such as coupling agents and solvents, etc., blended as necessary, further disperse, kneader, It can be prepared by performing a kneading process with a three-roll mill or the like and then defoaming.

  The conductive paste thus obtained is suitable for forming electrodes of electric / electronic parts, and has a thixo ratio (ratio of viscosity at 0.5 rpm and viscosity at 5 rpm at 25 ° C.) of 1.5. It is preferable that it is -4.5. If the thixo ratio is less than 1.5, stringing occurs at the time of dip coating at the time of electronic component manufacturing, while if the thixo ratio is more than 4.5, when used as an external electrode for electrical / electronic components at the time of dip coating, Cornering occurs and the dimensional stability is poor, and in either case, the yield as an electric / electronic component is deteriorated.

  Moreover, it is preferable that the film thickness of the electrically conductive paste hardened | cured material formed as an external electrode of an electrical / electronic component is 5-100 micrometers. If the film thickness is less than 5 μm, the coating property to the intended portion is poor and the coating film uniformity is poor, and pinholes are generated. If it exceeds 100 μm, dripping occurs when the paste is cured, and the coating film uniformity is applied.

  In the manufacturing process of electrical / electronic parts, the surface of the dip tank is flattened by the squeegee when the conductive paste is applied by dip coating. However, the viscosity change rate (thickening rate) of the conductive paste is increased due to the efficiency of continuous work. It is required to be 200% or less.

  The conductive paste of the present invention thus obtained is excellent in high thermal conductivity and heat dissipation, and when used as an internal electrode or external electrode of an electronic component, a remarkable improvement in characteristics is observed. For example, when it is used as an external electrode of an inductor, it can be directly metal-bonded with the coil, which can contribute to a reduction in resistance value and an improvement in reliability.

Next, the electric / electronic component and the manufacturing method thereof according to the present invention will be described.
The electrical / electronic component of the present invention is obtained by sintering the conductive paste of the present invention in contact with a noble metal, and the volume resistivity after sintering is 1 × 10 ⁻⁵ Ω · cm or less. It has a certain external electrode or internal electrode. When the volume resistivity is more than 1 × 10 ⁻⁵ Ω · cm, the sinterability is not sufficiently obtained, and thus the reliability may be deteriorated.

  In manufacturing the electric / electronic component of the present invention, the above-described conductive paste of the present invention is brought into contact with a noble metal and then sintered to form an external electrode or an internal electrode. At this time, in this invention, it can sinter by the conventional heating, and even if it sinters at the low temperature of 100-300 degreeC, electroconductivity can fully be ensured. In addition, this conductive paste has good continuous workability during dip coating and can efficiently form electrodes.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples at all.

(Examples 1-5, Comparative Examples 1-4)
Each component was mixed according to the composition of Table 1 and kneaded with a roll to obtain a resin paste. The obtained resin paste was evaluated by the following method. The results are shown in Table 1. In addition, the material used by the Example and the comparative example used what has the following characteristics.

Component (A) Flaky silver powder A (average particle size: 4.0 μm, Tap density: 5.5 g / cm ³ , content of carbon-containing compound: 0.3 mass%)
Flaky silver powder B (average particle size: 3.0 μm, Tap density: 3.8 g / cm ³ , content of carbon-containing compound: 0.4 mass%)

(A) ′ component Flaky silver powder C (average particle size: 1.5 μm, Tap density: 1.5 g / cm ³ , content of carbon-containing compound: 0.3 mass%)
Flaky silver powder D (average particle size: 25 μm, Tap density: 1.5 g / cm ³ , content of carbon-containing compound: 0.3 mass%)
Flaky silver powder E (average particle size: 4.0 μm, Tap density: 5.5 g / cm ³ , content of carbon-containing compound: 1.2% by mass)

  Here, the flaky silver powder of the component (A) and the component (A ′) is formed by a known method using a chemical reduction method to form a flaky silver powder containing a desired carbon-containing compound, and is classified by classification. It is a flaky silver powder having an average particle diameter and a Tap density.

(B) Component Silver nanoparticle A (made by DOWA Electronics Co., Ltd., trade name: Ag nano powder-1; average particle size: 20 nm)
Silver nanoparticles B (manufactured by DOWA Electronics Co., Ltd., trade name: Ag nano powder-2; average particle size: 60 nm)

(C) Component Acrylic resin: Hydroxylethylacrylamide (manufactured by Kojin Co., Ltd., HEAA)
Epoxy resin: Bisphenol F type liquid epoxy resin (Mitsubishi Chemical Corporation, trade name: YL983U)
Phenol resin: Bisphenol F (Honshu Chemical Industry Co., Ltd., trade name: Bisphenol F)

Other components Polymerization initiator: Dicumyl peroxide (manufactured by NOF Corporation, trade name: Park Mill D; decomposition temperature in rapid heating test: 126 ° C.)
Solvent: Butyl carbitol (manufactured by Tokyo Chemical Industry Co., Ltd.)
Curing accelerator: 1-benzyl-2-phenylimidazole (manufactured by Shikoku Chemicals Co., Ltd., trade name: 1B2PZ)

<Evaluation method>
[viscosity]
Using an E-type viscometer (3 ° cone), the value at 25 ° C. and 0.5 rpm was measured.

[Thixo ratio]
Using an E-type viscometer (3 ° cone), the viscosity at 0.5 rpm and 5 rpm was measured at 25 ° C., and the ratio of the viscosity of 0.5 rpm to 5 rpm (0.5 rpm viscosity / 5 viscosity) The thixo ratio was used.

[Content of carbon-containing compound in flaky silver powder]
Using a differential thermobalance-gas chromatography mass spectrometry simultaneous measurement apparatus (TG-DTA / GC-MS) (manufactured by Rigaku), the mass loss derived from long chain fatty acids in the flaky silver powder was measured.

[Volume resistance]
The conductive paste was applied to a glass substrate (thickness 1 mm) to a thickness of 30 μm by screen printing and cured at 200 ° C. for 60 minutes. The electrical resistance of the obtained wiring was measured by a 4-terminal method using a product name “MCP-T600” (manufactured by Mitsubishi Chemical Corporation).

[Thickening rate after continuous dipping]
Using a metal squeegee, the viscosity of the conductive paste after squeezing 500 times continuously was measured, and the thickening rate was calculated by the following formula. The measurement conditions for the viscosity were 25 ° C. and 0.5 rpm using an E-type viscometer (3 ° cone).
Thickening rate after squeegee (%) = conductive paste viscosity after squeegee test / conductive paste initial viscosity × 100

[Applying appearance]
A conductive paste was formed on both ends of the electronic component by dip coating, and heat-cured at 200 ° C. for 60 minutes. In this case, an electronic component that could not obtain dimensional stability due to the angle of the conductive paste was determined as NG. Judgment as to whether or not dimensional stability can be obtained was made by observing with an optical microscope whether or not a corner having a length of 0.1 mm or more occurred.

[Fixing strength]
A conductive paste was formed on both ends of the electronic component by dip coating, and heat-cured at 200 ° C. for 60 minutes. This was plated with Ni and Sn and mounted on a substrate with solder to produce an electronic component. The shear strength was measured by laterally pushing this electronic component at 20 mm / min, and the load when it was broken was defined as the fixing strength (N).

[Rate of change in resistance value after moisture resistance test]
A conductive paste was formed on both ends of the electronic component by dip coating, and heat-cured at 200 ° C. for 60 minutes. This was plated with Ni and Sn and mounted on a substrate with solder to produce an electronic component.
The electronic component is placed in a constant temperature and humidity chamber (temperature 85 ° C., humidity 85%), and an energization test (1A) is performed in this state. After 500 hours, 1000 hours, and 2000 hours, Relative values were calculated.

  From the above results, it was found that an electronic component using the conductive paste of the present invention has a good reliability and a highly reliable electronic component.

Claims (7)

(A) Flaky silver powder having an average particle diameter of 2 to 20 μm, a tap density (TD) of 2.0 to 7.0 g / cm ³ , and a carbon-containing compound content of 0.5% by mass or less;
(B) silver nanoparticles having an average particle diameter of 10 to 500 nm;
(C) a thermosetting resin;
An electrically conductive paste characterized by containing.   The ratio of each component to the total amount of the flaky silver powder of the component (A) and the silver nanoparticles of the component (B) is 50 to 95% by mass of the flaky silver powder of the component (A), and the silver nanoparticle of the component (B). The conductive paste according to claim 1, wherein the particle content is 5 to 50% by mass.   The conductive paste according to claim 1 or 2, wherein the carbon-containing compound of the component (A) is a long chain fatty acid or a long chain fatty acid derivative.   The conductive paste according to any one of claims 1 to 3, wherein a thixo ratio (ratio of a viscosity of 0.5 rpm to a viscosity of 5 rpm at 25 ° C) is 1.5 to 4.5. .   The flaky silver powder of the component (A) is 40 to 94.5% by mass, the silver nanoparticles of the component (B) is 5 to 50% by mass, and the thermosetting resin of the component (C) is 0.5 to 20%. The conductive paste according to claim 1, wherein the conductive paste is contained by mass%.   An electrical / electron comprising: forming the external electrode or the internal electrode by bringing the conductive paste according to any one of claims 1 to 5 into contact with a noble metal, followed by low-temperature sintering at 100 to 300 ° C. A manufacturing method for parts. The volume resistivity after sintering obtained by sintering the conductive paste according to any one of claims 1 to 5 in contact with a precious metal is 1 × 10 ⁻⁵ Ω · cm or less. An electric / electronic component having an external electrode or an internal electrode.