JP5531504B2 - Method for producing joined body using silver nanoparticles, and joined body - Google Patents

Description

  The present invention relates to various electrical and electronic products, and a method of manufacturing a joined body for joining an object to be joined such as an electronic component, wiring, circuit, electrode, device material, and semiconductor with a joining material containing silver nanoparticles, And a joined body obtained by the method.

  In general, the bonding material must cope with various temperature conditions depending on the bonding temperature, processing conditions applied after bonding, and the like. For example, there are types suitable for various temperatures such as high melting point solder, low melting point solder, eutectic solder, etc., but many control the content of tin and change the type of material to be mixed Have been dealt with. In recent years, lead-free solder has been actively developed as a countermeasure against environmental problems. Development of a bonding material using silver as a material that can meet these demands is increasing, and in particular, a bonding material using nano-sized silver particles is attracting attention. In general, when the metal particles are nano-sized, the surface energy is remarkably increased, so that the fusion temperature on the particle surface is greatly lowered as compared with the melting point of the bulk metal. Therefore, the metal nanoparticles are fused at a low temperature, but have the same high melting point as that of a normal bulk metal after the fusion. For this reason, the joint (joint) obtained using the joining material containing metal nanoparticles does not cause problems such as peeling even when exposed to high temperatures.

  In this way, although it is a metal nanoparticle that is expected to exhibit excellent performance as a bonding material, the fusion may proceed even at room temperature due to the high surface energy as described above. The surface needs to be protected and stabilized with various protective agents. Furthermore, with the miniaturization of electronic components, it is necessary to disperse metal nanoparticles in various media, such as when fine printing technology is applied in the method of using bonding materials. In addition, a device to combine various performances such as dispersion assistance has been studied. On the other hand, since the protective agent used here inhibits the progress of fusion of the metal nanoparticles during bonding, it is necessary to dissociate the protective agent from the surface of the metal nanoparticles during bonding. It is considered that the removal of the protective agent affects the heating temperature at the time of joining. In addition to the selection of the protective agent, there are various methods for preparing the joining material and joining methods. It has been proposed (see, for example, Patent Documents 1 to 3).

  For example, in Patent Document 1, an amine compound having a terminal amino group is used as a protective agent for metal fine particles, and an organic acid or an organic acid anhydride or a derivative thereof capable of reacting with the amine compound in a bonding material when heated. By adding amide, an amide bond is formed with the amine compound during heating (during bonding), and the dissociation of the protective agent from the surface of the metal fine particles is promoted to ensure bonding between the bulk metals. It has been devised to make. In Patent Document 1, since the object to be bonded is a metal, the upper limit of heating at the time of bonding is only required to be equal to or lower than the melting point of the object to be bonded. In the examples, heating is performed at 250 ° C. for 1 hour. Therefore, the amine compound as a protective agent and acids that can react with the amine compound are removed from the system, which is considered to contribute to sufficient bonding.

  In addition, the above-mentioned Patent Document 2 has a plurality of functional groups having both the property of binding to the surface of metal particles and the property of forming hydrogen bonds as a protective agent, and has a relatively molecular weight that usually evaporates at a low temperature of 200 ° C. or lower. By selecting a small organic compound, both the dispersibility (stabilization) of metal particles and the low temperature bonding property are combined. In the technique of Patent Document 2, bonding is performed by heating and pressurizing at 250 ° C. for several minutes, and although it is superior to the technique proposed in Patent Document 1 described above, it is basically a protective agent. In order to remove from the system, reliable bonding cannot be desired with heating below this level.

  Furthermore, in Patent Document 3, a bonding material containing metal particles protected with a secondary amine having a molecular weight of 250 or less is heated at a temperature of 50 to 400 ° C. for 1 second to 10 minutes to form a metal between objects to be bonded. A joining method for forming the sintered body has been proposed. By using a secondary amine, while maintaining the dispersibility of the metal particles, it is easy to peel off from the surface during heating, and it is a technology that has been devised so that it can be removed from the system even at low temperatures by having a low molecular weight, In the examples, heating and pressurization at 250 ° C. are performed, and it is not shown that bonding can be performed at low temperature and low pressure.

  As described above, in the studies up to now, it is assumed that the protective agent that protects the metal nanoparticles is removed from the system during heating and bonding in order to ensure bonding. Therefore, in order to perform low-temperature bonding while ensuring dispersion stability, the protective agent is limited to low molecular weight organic compounds, and heating above the evaporation / transpiration temperature is necessary. Even in the technology that praises, it is not carried out below 250 ° C. In the present situation where it is expected that the joining of electronic parts etc. to the plastics with lower heat resistance will be necessary with the miniaturization and weight reduction of electric and electronic devices in the future, using metal nanoparticles more There is a need for the development of materials that can be bonded at low temperatures.

JP 2002-126869 A JP 2009-120923 A JP 2009-167436 A

  The present invention has been made in view of the above problems, and is a joining material using metal nanoparticles, which does not impair the dispersion stability of the metal nanoparticles and can be joined even at a low temperature of 250 ° C. or lower. It is in providing the manufacturing method which obtains a conjugate | zygote using the possible joining material, and its conjugate | zygote.

  As a result of intensive studies to solve the above problems, the present inventor has found that a composite containing silver nanoparticles protected by an organic compound originally developed by the present inventors has a low-temperature fusibility, various substrates and materials. As a result of studying the excellent adhesion to the adhesive and the like and the suitability for the bonding material, the present inventors have found that the bonding property is excellent even at a low temperature of 250 ° C. or lower, and completed the present invention.

That is, the present invention is a method for producing a joined body that joins objects to be joined using a joining material containing an organic compound (X) and silver nanoparticles (Y),
The organic compound (X) is an organic compound in which polyethylene glycol (b) having a number average molecular weight of 500 to 5,000 is bonded to an amino group in polyethyleneimine (a) having a number average molecular weight of 500 to 50,000. (X1) or polyethylene glycol (b) having a number average molecular weight of 500 to 5,000 and an amino group in polyethyleneimine (a) having a number average molecular weight of 500 to 50,000, and a linear epoxy resin (c) And an organic compound (x2) formed by bonding, and
A method for producing a joined body, characterized in that a layer of the joining material is provided between joined parts of an object to be joined, and then heated and joined at 100 to 250 ° C., and the joined body obtained by the method. Is to provide.

  The method for producing a joined body according to the present invention uses a joining material containing silver nanoparticles protected by a specific organic compound, and the conductive material or the like by heat treatment at an unprecedented low temperature of 100 to 250 ° C. This is a method for bonding semiconductor materials and the like, and can be suitably applied to an object to be bonded having low heat resistance. Further, it has a bonding property for fixing the bonded conductive material or the like on various substrates, and is useful for a flexible plastic substrate or the like. Further, it can be applied to a portion where pressure cannot be applied, and can be applied to various bonding techniques such as wire bonding and anisotropic conductive material connection.

Hereinafter, the present invention will be described in detail.
The method for producing a joined body of the present invention is a method for producing a joined body for joining members to be joined using a joining material containing an organic compound (X) and silver nanoparticles (Y),
The organic compound (X) is an organic compound in which polyethylene glycol (b) having a number average molecular weight of 500 to 5,000 is bonded to an amino group in polyethyleneimine (a) having a number average molecular weight of 500 to 50,000. (X1) or polyethylene glycol (b) having a number average molecular weight of 500 to 5,000 and an amino group in polyethyleneimine (a) having a number average molecular weight of 500 to 50,000, and a linear epoxy resin (c) And an organic compound (x2) formed by bonding, and
A layer of the bonding material is provided between the bonding sites of the objects to be bonded, and then heated and bonded at 100 to 250 ° C.

  Conventionally, in a bonding material containing metal nanoparticles such as silver nanoparticles, a protective agent used to prevent fusion of the nanoparticles at room temperature inhibits fusion of the metal nanoparticles due to heating, and as a result It has been thought to hinder sufficient bonding between the bonds. Therefore, a protective agent made of a relatively high molecular weight organic compound is preferable in order to impart storage stability of metal nanoparticles and easy dispersibility in various media. It should be said that it is difficult to apply applied metal nanoparticles to a bonding material (see Patent Document 2).

  Under such a background, as a result of studying the desorption behavior of the protective agent in a silver nanoparticle having a specific organic compound described below as a protective agent, the protective agent is a silver nanoparticle even at an unprecedented low temperature. From the above, it was found that the protective agent (organic compound) that had been released did not interfere with the fusion of the silver nanoparticles, and also exhibited the adhesion between the fused silver and the object to be joined. It has been found that it contributes, and it is not necessary to remove the protective agent out of the system at all, so that low-temperature bonding has been realized.

  The silver nanoparticles (Y) in the present invention have an average particle diameter (100 particles randomly extracted and averaged) observed in a transmission electron micrograph of 100 nanometers or less. It does not require that the shape be a perfect sphere. Moreover, the number average molecular weight of each segment which comprises organic compound (X) is a polystyrene conversion value measured by gel permeation chromatography (GPC). Further, the bonding material is composed of the organic compound (X) and the silver nanoparticles (Y) as main components in the nonvolatile content, and the main component is composed of the silver nanoparticles (Y) as the organic compound (X). It consists of a nanometer-order composite consisting of a structure protected by “Containing as a main component” means that no components other than unreacted raw materials and raw materials derived from raw materials are not included when the third component is not added intentionally.

  In the polyethyleneimine (a) constituting the organic compound (X) used in the present invention, the ethyleneimine unit in the chain can be coordinated with silver and its ions, and further promotes the reduction of silver ions, thereby This is a polymer chain that stabilizes and holds the silver nanoparticles (Y) as particles (Y). The structure has an ethyleneimine unit as the main repeating unit, and may be linear or branched, and may be either a commercial product or a synthetic product.

  The size of the complex is not only the molecular weight of the organic compound (X) to be used, but also the components constituting the organic compound (X), that is, polyethyleneamine (a), polyethylene glycol (b), and linear epoxy It is also affected by the structure and composition ratio of the resin (c) and the type of silver compound used as a raw material. In the case of polyethyleneimine (a) having the same molecular weight, if the degree of branching is small, the resulting composite has a large particle size, and the particle size tends to decrease as the degree of branching increases. In order to increase the content of silver nanoparticles (Y) in the composite, it is preferable to use branched polyethyleneimine.

  A commercially available branched polyethyleneimine is branched by a tertiary amine and can be used as a raw material for the organic compound (X) used in the present invention. From the point of obtaining a composite having excellent storage stability, the degree of branching is in the range of (1-49) / (100) in terms of the molar ratio of (tertiary amine) / (all amines). It is preferable, and the more preferable range of the degree of branching is (15 to 40) / (100) in view of industrial production and availability.

  As the number average molecular weight of the polyethyleneimine (a) part, if it is too low, the retention ability of the silver nanoparticles (Y) by the organic compound (X) tends to be lowered, and the storage stability may be insufficient. If it is too high, the organic compound (X) becomes a huge aggregate, which may hinder the storage stability of the complex. Therefore, from the viewpoint of the ability to fix the silver nanoparticles (Y) in the obtained composite and the ability to prevent the composite from becoming too large, the number average molecular weight of the polyethyleneimine (a) is 500 to 50. In the range of 1,000,000, preferably in the range of 1,000 to 40,000, and most preferably in the range of 1,800 to 30,000.

  The polyethylene glycol (b) constituting the organic compound (X) used in the present invention is a hydrophilic segment, and facilitates stabilization by easily dispersing the complex in a hydrophilic solvent. When the molecular weight of the polyethylene glycol (b) is dispersed in a hydrophilic solvent, the dispersion stability may be deteriorated if the molecular weight is too low, and the composite may be aggregated if the molecular weight is too high. Therefore, in order to obtain a composite with more excellent dispersibility and storage stability, it is essential that the number average molecular weight of the polyethylene glycol (b) is in the range of 500 to 5,000, and 1,000 to 3 , 000 is preferable.

  The polyethylene glycol (b) may be a commercially available product or a synthetic product. Further, it may be a copolymer with other hydrophilic polymer. Examples of the hydrophilic polymer that can be used at this time include polyvinyl alcohol, polyacrylamide, polyisopropylacrylamide, and polyvinylpyrrolidone. From the viewpoint of increasing the content of silver nanoparticles (Y) in the resulting composite, even when using a copolymer, the overall molecular weight is preferably in the range of 500 to 5,000.

  The organic compound (x2) used in the present invention is obtained by further bonding a linear epoxy resin (c) as a hydrophobic segment. When the organic compound (x2) is dispersed in water or a hydrophilic solvent by including a structure derived from the linear epoxy resin (c) in the organic compound (x2), the intermolecular or intermolecular mutual With a strong associative force, a micelle core is formed, a stable micelle is formed, and silver nanoparticles (Y) are taken into the stable micelle, thereby obtaining a stable dispersion.

  The linear epoxy resin (c) can be used without particular limitation as long as it is generally commercially available or can be synthesized. Examples thereof include bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, xanthene type epoxy resin described in JP-A No. 2003-201333, and the like. The above may be mixed. Among these, when the composite obtained is used as a bonding material, it is preferable to use a bisphenol A type epoxy resin particularly from the viewpoint of excellent adhesion to a metal substrate. In addition, these linear epoxy resins may be used as raw materials for the organic compound (x2) as they are, and may be modified with various modifications according to the structure of the target organic compound (x2). good. For example, a part of the epoxy group in the epoxy resin (c) can be opened in advance with a compound having an aromatic ring having an interaction with a metal, and applied to a bonding material having better adhesion.

  In addition, the molecular weight of the linear epoxy resin (c) is not particularly limited, but when dispersed in a hydrophilic organic solvent, dispersion stability is deteriorated if it is too low, and micelles are formed if it is too high. There is a possibility of aggregation. From these viewpoints, the number average molecular weight of the linear epoxy resin (c) is usually 350 to 20,000, and preferably 400 to 10,000.

  Although it does not specifically limit as a manufacturing method of organic compound (X) used by this invention, The thing by the following method is preferable from the point which can synthesize | combine a compound as designed easily.

  As described above, a commercially available or synthesized polyethyleneimine (a) can be suitably used. First, a case where branched polyethyleneimine is used will be described.

  Since the terminal of the branched polyethyleneimine is a primary amine, the terminal of polyethylene glycol (b) can be used in the present invention by pre-modifying and reacting with a functional group that reacts with the primary amine. An organic compound (x1) can be synthesized. The functional group that reacts with the primary amine is not particularly limited. For example, aldehyde group, carboxy group, isocyanate group, tosyl group, epoxy group, glycidyl group, isothiocyanate group, halogen, acid chloride, sulfonic acid Examples include chloride. Among them, a carboxy group, an isocyanate group, a tosyl group, an epoxy group, and a glycidyl group are advantageous in terms of production, such as reactivity and ease of handling, and are preferred functional groups.

  In addition, the functional group may not be a functional group that directly reacts with the primary amine, but may be any functional group that can be reacted with the primary amine by performing various treatments. For example, polyethylene glycol having a hydroxy group may be used. For example, it may be reacted with a polyethyleneimine chain by a technique such as glycidylation. Furthermore, after performing the process which converts the primary amine of a branched polyethyleneimine chain | strand into the other functional group which can react with the polyethyleneglycol which has a functional group, these are made to react and an organic compound (X) is synthesize | combined. It is also possible.

  When the polyethyleneimine chain (a) is a linear polyethyleneimine chain, a polymer compound is obtained by first synthesizing a polyacylated ethyleneimine chain by living polymerization, and subsequently introducing polyethylene glycol. Examples include a method of hydrolyzing an ethyleneimine chain to form a linear polyethyleneimine chain.

  The method for synthesizing the organic compound (x2) used in the present invention has already been provided by the present inventors (Japanese Patent Laid-Open No. 2006-213877, Japanese Patent Laid-Open No. 2008-045024, etc.). A compound having a molecular weight in the range of may be synthesized.

  The molar ratio (a) :( b) of the polymer constituting the chain of each component of polyethyleneimine (a) and polyethylene glycol (b) in the organic compound (x1) used in the present invention is not particularly limited. However, from the viewpoint of excellent storage stability of the obtained composite, it is usually in the range of (a) :( b) = 1: 1 to 100, and preferably designed to be 1: 1 to 30.

  When the organic compound (x2) is used, the molar ratio (a) :( b) :( c) of the polymer constituting the chain of each component of polyethyleneimine (a), polyethylene glycol (b), and linear epoxy resin (c) ) Is not particularly limited, but is usually in the range of (a) :( b) :( c) = 1: 1 to 100: 1 to 100 from the viewpoint of excellent storage stability of the resulting composite. In particular, it is preferable that the design is 1: 1 to 30: 1 to 30.

  The organic compound (X) used in the present invention is different from the polyethyleneimine (a) in which the silver nanoparticles (Y) can be stably present, and in the organic compound (x1), the polyethylene glycol (b), the organic compound ( x2) has a structure derived from polyethylene glycol (b) and linear epoxy resin (c). As described above, the polyethylene glycol (b) portion exhibits a high affinity with the solvent in the hydrophilic organic solvent, and the linear epoxy resin (c) portion exhibits a strong associative force in the hydrophilic organic solvent. Show. Furthermore, when the linear epoxy resin (c) has an aromatic ring, the π electron of the aromatic ring interacts with silver, thereby contributing to further stabilizing the dispersibility of the composite. Is also possible.

  In the method for producing the composite, first, the organic compound (X) is dissolved or dispersed in an aqueous medium, that is, water or a mixed solvent of water and a hydrophilic organic solvent. In the case of organic compound (x1), polyethyleneimine (a) and polyethylene glycol (b), in the case of organic compound (x2), polyethyleneimine (a) and polyethylene glycol (b), and linear epoxy resin (c) Depending on the combination, solubility and dispersibility in an aqueous medium are different, but it is necessary to uniformly dissolve or disperse them. The hydrophilic organic solvent that can be used here may be any one that can be mixed at least 5 parts by mass with respect to 100 parts by mass of water at 25 to 35 ° C. to obtain a uniform mixed solvent. , Ethanol, isopropyl alcohol, n-propyl alcohol, tetrahydrofuran, dioxane, acetone, methyl ethyl ketone, dimethylacetamide, dimethylformamide, ethylene glycol, propylene glycol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol dimethyl ether, propylene glycol dimethyl ether, diethylene glycol Glycerin, dimethylsulfone oxide, dioxirane, N-methylpyrrolidone, dimethylimidazolidinone, sulfo Can be exemplified emissions etc., may be used individually or as a mixture of two or more. Various ionic liquids may be used.

  As the use ratio of the organic compound (X) and the aqueous medium, the viewpoint of the ease of handling and the ease of the reduction reaction of silver ions, the content of silver nanoparticles (Y) in the obtained composite From the viewpoint of improvement, the concentration of the organic compound (X) is preferably 1 to 20% by mass, and more preferably 2 to 15% by mass. At this time, when the solubility / dispersibility of the organic compound (X) is insufficient, for example, ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, etc. are used in combination. Solubility and dispersibility can be adjusted by using a mixed solvent. In order to dissolve or disperse the organic compound (X), it is usually sufficient to stand or stir at room temperature (25 ° C.), and ultrasonic treatment, heat treatment or the like may be performed as necessary. Further, when the compatibility with the aqueous medium is low due to the crystallinity of the organic compound (X), for example, the organic compound (X) is dissolved or swollen with a small amount of a good solvent, and then in the target aqueous medium. It is also possible to use a method of dispersing them. At this time, it is more effective to perform ultrasonic treatment or heat treatment (about 80 ° C.).

  After preparing the solution or dispersion of the organic compound (X), the silver compound is mixed. At this time, from the viewpoint of increasing the content of the silver nanoparticles (Y) in the composite, the organic compound (X) It is preferable to use 400 to 9900 parts by mass as silver with respect to 100 parts by mass. Furthermore, it is preferable to mix so that it may become 2-80 mass% as a non volatile matter from a viewpoint which improves productivity by reducing the usage-amount of an aqueous medium, and can control a reductive reaction easily. More preferably, it is used so that it may become 900-9900 mass parts as silver, and 3-50 mass% as a non volatile matter with respect to 100 mass parts of organic compound (X).

  At this time, as a silver compound that can be used, any silver compound (Y) can be obtained by a reduction reaction. Examples thereof include silver nitrate, silver oxide, silver acetate, silver fluoride, silver acetylacetonate, and benzoic acid. Silver oxide, silver carbonate, silver citrate, silver hexafluorophosphate, silver lactate, silver nitrite, silver pentafluoropropionate, etc., from the viewpoint of ease of handling and industrial availability, silver nitrate or silver oxide It is preferable to use it.

  In the step, the method of mixing the silver compound with the aqueous medium in which the organic compound (X) is dissolved or dispersed is not particularly limited, and the organic compound (X) is dissolved or dispersed. A method of adding a silver compound to a medium, a reverse method thereof, or a method of mixing while simultaneously putting in another container may be used. A mixing method such as stirring is not particularly limited.

  At this time, in order to accelerate the reduction reaction, it may be heated to about 30 to 70 ° C. as necessary, or a reducing agent may be used in combination.

  The reducing agent is not particularly limited. For example, hydrogen, hydrogenation can be performed because the reduction reaction can be easily controlled and can be easily removed from the reaction system in a subsequent purification step. Boron compounds such as sodium boron and ammonium borohydride, alcohols such as methanol, ethanol, propanol, isopropyl alcohol, ethylene glycol and propylene glycol, aldehydes such as formaldehyde, acetaldehyde and propionaldehyde, ascorbic acid, citric acid and citric acid It is preferable to use acids such as sodium and hydrazines such as hydrazine and hydrazine carbonate. Among these, sodium borohydride, ascorbic acid, sodium citrate and the like are more preferable from the viewpoint of industrial availability and handling.

  The addition amount of the reducing agent is not particularly limited as long as it is an amount necessary for reducing silver ions, and the upper limit is not particularly specified, but it is 10 mol times or less of silver ions. Is preferable, and it is more preferable that it is 2 mol times or less.

  Moreover, the addition method of a reducing agent is not limited, For example, a reducing agent can be mixed as it is, or it dissolves and disperses | distributes in aqueous solution or another solvent. Further, the order in which the reducing agent is added is not limited. Even if the reducing agent is added to the solution or dispersion of the organic compound (X) in advance, the reducing agent is added at the same time when the silver compound is mixed. Furthermore, after mixing several hours after mixing the solution of organic compound (X), or a dispersion liquid, and a silver compound, the method of mixing a reducing agent may be used.

  In particular, when using a raw material that does not dissolve or hardly dissolves in an aqueous medium such as silver oxide or silver chloride, a complexing agent may be used in combination. Examples of the complexing agent include propylamine, butylamine, diethylamine, dipropylamine, triethylamine, ammonia, ethylenediamine, N, N, N ′, N′-tetramethylethylenediamine, 1,3-diaminopropane, N, N , N ′, N′-tetramethyl-1,3-diaminopropane, triethylenetetramine, methylaminoethanol, dimethylaminoethanol, ethanolamine, diethanolamine, methyldiethanolamine, propanolamine, butanolamine, dimethylaminopropanol and the like. .

  The amount of the complexing agent added is not particularly limited as long as it is sufficient to be coordinated with silver oxide or the like to form a complex, and the upper limit is not particularly specified. It is preferable that it is 20 mole times or less. The method for adding the complexing agent is not limited. For example, the complexing agent can be mixed as it is or dissolved or dispersed in an aqueous solution or other solvent.

  The time required for the reduction reaction varies depending on the presence or absence of a reducing agent and the type of organic compound (X) used, but is usually 0.5 to 48 hours, and is adjusted to 0.5 to 24 hours from the viewpoint of industrial production. It is preferable. Examples of the preparation method include a method depending on the heating temperature, the amount of reducing agent and complexing agent added, and the timing thereof.

  After carrying out the reduction reaction, the purification step is started. At this time, it is preferable to perform concentration after adding an organic solvent. The concentration method is not particularly limited, and any of dialysis, centrifugation, precipitation, etc. may be used, or they may be used simultaneously. The organic solvent that can be used at this time is not particularly limited, but the viewpoint that the time required for the concentration step can be shortened, the organic solvent can be reused, and the mixture obtained in the previous step is mixed. From the viewpoint of being easy to handle, it is preferable to use an organic solvent having a boiling point of 120 ° C. or lower, preferably 100 ° C. or lower. The amount used is not particularly limited, but it is preferable to mix the mixture obtained in the previous step so that the amount is 1.5 to 5 times, preferably 2 to 3 times. Further, as a concentration method, it is preferable to use a centrifugal separation method from the viewpoint of excellent industrial productivity. In this centrifugal concentration step, in addition to a part of the medium used in the previous step, the purpose is to remove a reducing agent and a complexing agent added as necessary, a counter ion of silver ions, and the like. . Therefore, it is preferable to use a concentration method according to the raw material used in the previous step, and the nonvolatile content is concentrated to 30% by mass or more, preferably 50% by mass or more.

  In general, metal nanoparticles in the size region of several tens of nm have characteristic optical absorption due to surface plasmon excitation, depending on the metal species. Therefore, by measuring the plasmon absorption of the obtained dispersion, it can be confirmed that silver is present as fine particles of nanometer order in the dispersion, and further, the dispersion is cast. It is also possible to observe the average particle diameter, distribution width, etc. in a TEM (transmission electron microscope) photograph of the film obtained in this manner.

  The concentrate obtained above can be used as a bonding material as it is. Furthermore, a desired dispersion medium, which will be described later, may be appropriately added to the concentrate once concentrated, and the mixture may be stirred and mixed to form a dispersion. In addition, the powder obtained by pulverizing the concentrate by vacuum drying, freeze drying, or the like may be used as it is, and the powder is dispersed in a desired dispersion medium to be described later and used as a new dispersion. There may be.

  The composite can be dispersed in various dispersion media depending on the purpose of use of the bonding material used in the present invention. Various hydrophilic solvents, hydrophobic solvents, or mixed solvents thereof can be selected and used for the dispersion medium. Among these, from the point that a uniform dispersion can be easily obtained, a solvent comprising a compound having a hydroxy group is preferable, and water alone or a mixed solvent of water and alcohol such as methanol, ethanol, isopropyl alcohol or the like. Is most preferred.

  Examples of the hydrophilic solvent include water, methanol, ethanol, isopropyl alcohol, tetrahydrofuran, acetone, dimethylacetamide, dimethylformamide, ethylene glycol, diethylene glycol, propylene glycol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol dimethyl ether, propylene. Glycol dimethyl ether, dimethyl sulfone oxide, dioxirane, N-methylpyrrolidone and the like can be mentioned, and these may be used alone or in admixture of two or more.

  Examples of the hydrophobic solvent include hexane, cyclohexane, ethyl acetate, butanol, methylene chloride, chloroform, chlorobenzene, nitrobenzene, methoxybenzene, toluene, xylene, and the like. good.

  Examples of other solvents that can be used by mixing with a hydrophilic solvent or a hydrophobic solvent include propyl acetate, butyl acetate, isobutyl acetate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, and the like. What is necessary is just to select suitably according to the use application etc. of the joining material to be used.

  Further, the concentration of silver nanoparticles (Y) in the bonding material is not particularly limited, but the silver content in the bonding material is usually 10 to 98% by mass from the viewpoint of bonding properties and conductivity. Yes, and preferably 20 to 60% by mass. The concentration of silver nanoparticles (Y) in the bonding material can be adjusted according to the form of the field to be used. In addition, the bonding material can be prepared and used in the form of powder or paste, and the viscosity when used as a paste is not particularly limited, but it is suitable for printing methods such as inkjet devices and screen printing. From the viewpoint of application, 1 to 20,000 mPa.s. S is preferred.

  The method of dispersing the composite obtained by the above-described method in the above-mentioned dispersion medium to form a dispersion is not particularly limited, and is not limited to a bead mill, a paint conditioner, an ultrasonic homogenizer, a fill mix, a homogenizer, a disper, The dispersion may be performed by a stirring method using an apparatus such as a three-one motor, an ultrasonic method, a mixer method, a three-roll method, or a ball mill method. In order to obtain a bonding material having a good dispersion state, it is possible to perform dispersion by combining a plurality of methods among these dispersion methods.

  The bonding material used in the present invention is excellent in bondability by itself, but further improves the bondability, dispersion stability and storage stability when a bonding material containing a dispersion medium such as an organic solvent is used. In order to improve the property, a hydrophilic polymer may be added. The hydrophilic polymer is not particularly limited. For example, polyoxyethylene, polyoxypropylene, polyvinyl alcohol, partially saponified polyvinyl alcohol, polyethylene glycol, polyethyleneimine, polypropyleneimine, polyhydroxyethyl acrylate, polyhydroxyethyl methacrylate. , Dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, polyacetylethyleneimine, polyacetylpropyleneimine, polypropionylethyleneimine, polypropionylpropyleneimine, polyacrylamide, polyisopropylacrylamide, polyvinylpyrrolidone, polyacyloxazoline, polyethyloxazoline, poly Polymers such as propyloxazoline or the above polymers Ri 2 or more graft polymers consisting of a polymer chain selected can include block polymers. Among these, from the viewpoint of the adhesion to plastics to be bonded and the dispersion stability when used as a bonding material, polyethylene glycol, polyethyleneimine, polyvinyl alcohol, amino (meth) acrylate, polyvinylpyrrolidone, polyoxazoline, It is preferable to use a reaction product of polyethylene glycol and polyethyleneimine.

  Furthermore, the component that can be mixed as an additive when used as a bonding material is not particularly limited, and may be various bonding objects such as a coupling agent, various conductive components, electronic components, and the like. Ingredients that improve bonding properties, components that control the surface during application of leveling agents, solvents having various boiling points, viscosity modifiers, various polymers other than the hydrophilic polymers, ceramics, crosslinking agents, etc. it can.

  In particular, the bonding material containing the composite obtained as described above preferably contains a compound (Z) having a functional group capable of reacting with a nitrogen atom in the polyethyleneimine (a). By adding the compound (Z), the low-temperature bonding property can be further improved. The addition method is not particularly limited, and for example, the compound (Z) can be mixed as it is or dissolved or dispersed in an aqueous solution or other solvent.

  The compound (Z) can be used without particular limitation as long as it is generally commercially available or can be synthesized. Specifically, the compound (Z) reacts with a nitrogen atom in the polyethyleneimine (a) to produce an alcohol. Aldehyde compounds, epoxy compounds, acid anhydrides, carboxylic acids, inorganic acids and the like that form amide bonds, form amide bonds, and form quaternary ammonium ions. For example, formaldehyde, acetaldehyde, propionaldehyde, acrolein, benzaldehyde, cinnamaldehyde, perylaldehyde, ethylene oxide, propylene oxide, butylene oxide, 2,3-butylene oxide, isobutylene oxide, 1-methoxy-2-methylpropylene oxide, butyric acid-glycidyl Glycidyl methyl ether, 1,2-epoxyhexane, 1,2-epoxyheptane, 1,2-epoxyoctane, 1,2-epoxydecane, 1,2-epoxydodecane, 1,4-butanediol diglycidyl ether, 1,2-epoxy-5-hexene, 1,2-epoxy-9-decene, 2-phenylpropylene oxide, stilbene oxide, glycidyl methyl ether, ethyl glycidyl ether, Tyl glycidyl ether, glycidyl isopropyl ether, tert-butyl glycidyl ether, allyl glycidyl ether, glycidyl phenyl ether, benzyl glycidyl ether, glycidyl stearate, epoxysuccinic acid, 1,5-hexadiene diepoxide, 1,7-octadiene diepoxide 2,2-bis (4-glycidyloxyphenyl) propane, ethylene glycol diglycidyl ether, neopentyl glycol glycidyl ether, acetic anhydride, maleic anhydride, citraconic anhydride, diacetyl-tartaric anhydride, phthalic anhydride, 1,2-cyclohexanedicarboxylic anhydride, 1-cyclohexene-1,2-dicarboxylic anhydride, o-acetyl-malic anhydride, (2-methyl-2-propenyl) succinic acid Anhydride, 1,2-naphthalic anhydride, 2,3-naphthalenedicarboxylic anhydride, 2,3-anthracene dicarboxylic anhydride, 2,3-dimethylmaleic anhydride, 3-methylglutaric anhydride, 3-methylphthalic anhydride, 4-methoxybenzoic anhydride, 4-methylphthalic anhydride, benzoic anhydride, succinic anhydride, butyl succinic anhydride, decyl succinic anhydride, dodecyl succinic anhydride, Hexadecyl succinic anhydride, octadecyl succinic anhydride, octadecenyl succinic anhydride, isooctadecenyl succinic anhydride, tetradecenyl succinic anhydride, nonenyl succinic anhydride, trimellitic anhydride, butyric anhydride, Propionic acid anhydride, heptanoic acid anhydride, decanoic acid anhydride, n-octanoic acid anhydride, nonanoic acid anhydride, oleic acid Water, valeric anhydride, palmitic anhydride, phenoxyacetic anhydride, pivalic anhydride, stearic anhydride, crotonic anhydride, diglycolic anhydride, glutaric anhydride, exo-3,6- Epoxy-1,2,3,6-tetrahydrophthalic anhydride, itaconic anhydride, formic acid, acetic acid, propionic acid, ascorbic acid, citric acid, tartaric acid, maleic acid, fumaric acid, succinic acid, oxalic acid, benzoic acid , P-toluenesulfonic acid, glucuronic acid, hyaluronic acid, gluconic acid, hydrogen peroxide, phosphoric acid, nitric acid, nitrous acid, boric acid and the like may be used alone or in combination of two or more. Also good.

  The amount of the compound (Z) to be added is not particularly limited, but is usually 0.1% with respect to the ethyleneimine unit in the polyethyleneimine (a) from the viewpoint of excellent storage stability of the obtained bonding material. It is preferably in a range of ˜5 times molar equivalent, and more preferably 0.25 to 1 times molar equivalent.

  The bonding material used in the present invention is only required to have the specific organic compound (X) and the silver nanoparticles (Y) as essential components as described above, and has excellent low-temperature bonding properties. Is preferably in the range of 100 to 150 ° C. in the dry state of the bonding material. The melting point is a value obtained by measuring with DSC.

  There are no particular limitations on the material, shape, and the like of the bonding surface of the objects to be bonded used when bonding is performed using the bonding material obtained above. Since a bonding material containing metal nanoparticles is generally used as a conductive bonding material, the bonding surface of an object to be bonded is a conductive material or a semiconductor material. Metal, alloy, metal oxide, semiconductor , Conductive polymers and the like. For the purpose of fixing or sealing the object to be bonded, one of the objects to be bonded may be made of an insulating material.

  Therefore, examples of the object to be bonded used in the bonding method of the present invention include inorganic materials such as glass, silicon, metal, and metal oxide, organic materials such as resin (plastic) and cellulose, and further glass, metal, and metal. An oxide surface etched or a resin surface plasma-treated or ozone-treated can be used.

  Although it does not specifically limit as glass, For example, glass, such as heat resistant glass (borosilicate glass), soda lime glass, crystal glass, optical glass which does not contain lead and arsenic, can be used conveniently. In the use of glass, the surface can be used by etching with an alkali solution such as sodium hydroxide, if necessary.

  Although it does not specifically limit as a metal, For example, iron, copper, aluminum, stainless steel, zinc, silver, gold | metal | money, platinum, or these alloys etc. can be used.

  Although it does not specifically limit as a metal oxide, For example, ITO (indium tin oxide), a silica, a titanium oxide, a tin oxide, copper oxide, a zinc oxide, an alumina etc. can be used.

  Examples of the plastic include polyethylene, polypropylene, polycarbonate, polyester, polystyrene, unsaturated polyester resin, vinyl chloride resin, epoxy resin, phenol resin, melamine resin, urea resin, AS resin, ABS resin, poly (meth) acrylate, poly Of various polymers such as (meth) acrylamide, polyvinyl alcohol, vinylidene chloride resin, acetal resin, polyamide, polyurethane, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyimide, polyethersulfone, liquid crystal polymer, polyphenylene sulfide, polysulfone, etc. Processed products can be used. In using various polymers, the surface may be treated with plasma or UV irradiation, or may be treated with sulfuric acid or alkali, if necessary.

  The shape of the object to be joined is not particularly limited, and may be a flat or curved sheet or film. In addition, a tubular tube, a spiral tube of a tubular tube, a micro tube; a container having an arbitrary shape (for example, a spherical shape, a square shape, a triangular shape, a cylindrical shape); an arbitrary shape (for example, a cylindrical shape, (Rectangle, triangle, etc.) A rod or a solid in a fiber state can be suitably used. In particular, in order to cope with the recent reduction in size and weight of electronic devices, a plastic film or a sheet-like flexible base material is often used, but the joining method of the present invention is also suitable for such fields. It is possible to apply to.

  The method for forming the bonding material layer between the objects to be bonded is not particularly limited, and the paste or powdered bonding material is processed into a dropper, pipette, spatula tool or pellet and pasted. In addition to printing, a printing method, a dry coating method, or the like may be used. Examples of the application by the printing method include an inkjet method, a reverse printing method, an offset printing method, a gravure printing method, a dispensing method, a screen printing, a dot-like printing, and the like.

  As examples other than printing methods, filling methods used in various apparatuses for mounting, electrolytic plating, electroless plating, bonding plating methods, filling methods used in face-down methods, spin coaters, bar coaters, applicators, Examples thereof include a dipping method, a method using a flow gun or a flow coater, a spraying method such as spraying, brush coating, puff coating, roller coating and the like.

  Furthermore, examples of coating using powder include electrostatic coating method by corona charging or tribo charging, fluidized immersion method, frame spray method, electric field cloud method, vacuum deposition, sputtering, ion plating, ion beam film formation, chemical Examples include vapor deposition.

  In the present invention, the layer made of the bonding material obtained as described above is provided between the objects to be bonded, and then the bonding portion is heated at 100 to 250 ° C. to obtain a bonded body. The method is not particularly limited. For example, joining parts such as those in which the joining material is coated, coated, or laminated on the joining surface by the above-described method, such as a trowel, an electric furnace, a dryer, an oven, a thermostatic bath, a hot stage, etc. Examples thereof include a method of heating using a heating device, a method of heating after naturally drying at room temperature of 25 ° C. to 30 ° C., and a method of heating while applying pressure to the bonding site.

  It is desirable that the heating conditions are appropriately selected according to the use, the article to be joined, the additive, and the like. Since the bonding material used in the present invention needs to advance the fusion of the silver nanoparticles (Y) by desorption of the protective agent [organic compound (X)] from the surface of the silver nanoparticles (Y), Although heating at 100 ° C. or higher is necessary, the upper limit of the heating temperature is not particularly required. For example, even if heated to 300 ° C. or higher, as long as it does not cause melting of the object to be bonded, it is possible to bond the object to be bonded by generating a silver fused body by fusing silver nanoparticles (Y). It is. However, in consideration of the fact that the organic compound (X) is preferably at a temperature at which the organic compound (X) is not decomposed from the viewpoint of expressing the effect of improving the adhesion by the organic compound (X) contained in the bonding material of the present invention. In addition, the upper limit temperature of heating is set to 250 ° C. in view of energy cost and environmental consideration.

  Moreover, you may join by applying a pressure simultaneously or continuously with a heating. If the pressure is too high, there is a concern that the base material, parts, wiring, etc. that are to be joined may crack or break, but their strength varies depending on the type, and the upper limit when applying pressure Cannot be determined. However, as an example for avoiding such a situation, 10 kPa to 10 MPa is preferable if preferable pressure conditions are given. When the strength of the base material, parts, wiring, etc. is even weaker, 10 kpa to 3 MPa is more preferable.

  The joined body of the present invention is obtained by the above-described manufacturing method, and the joined part contains a fused body (bulk silver) of silver nanoparticles (Y) and an organic compound (X). Features. At this time, when the bonding material contains a compound having a functional group capable of reacting with the organic compound (X), the bonding is performed as a modified product in which a part of the organic compound (X) used as a raw material is modified. It will be included in the part. In addition, since the organic compound (X) contained in the above-mentioned bonding material is hardly decomposed at 250 ° C. or less, there is little generation of decomposition products (gas), and it is also difficult for voids or the like to be generated at the bonding site. It is a feature. Furthermore, various additives and hydrophilic polymers blended in the bonding material are also included in the form as it is or partially modified depending on the heating conditions. Since the silver nanoparticle (Y) content in the above-described composite can be 95% by mass or more, the silver content in the bonding part can be increased, and the bonding part has conductivity. It is also easy to give. In addition, since the bonded portion of the bonded body obtained in this way is basically composed of bulk silver, it has excellent heat resistance and is exposed to high temperatures during secondary processing of the bonded body. Even in such a case, problems such as peeling are unlikely to occur.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, “%” represents “mass%”. Hereinafter, Examples 1, 4, 5-7, and 9-10 are read as Preparation Examples 1, 4, 5-7, and 9-10, respectively. Examples 2, 3 and 8 are read as Examples 1, 2 and 3, respectively.

In the following examples, the equipment used is as follows.
¹ H-NMR: manufactured by JEOL Ltd., AL300, 300 Hz
TEM observation: JEM-2200FS, manufactured by JEOL Ltd.
TGA measurement: SII Nano Technology Co., Ltd., TG / DTA6300
Plasmon absorption spectrum: manufactured by Hitachi, Ltd., UV-3500
DSC measurement: SII Nano Technology Co., Ltd., DSC7200

Synthesis Example 1 Synthesis of Organic Compound (x1) and Synthesis of Complex Using the Compound 1-1 [Tosylation Reaction of Polyethylene Glycol]
Under a nitrogen atmosphere, 9.6 g of p-toluenesulfonic acid chloride was added to a mixed solution of 20.0 g (10.0 mmol) of methoxypolyethylene glycol [Mn = 2,000], 8.0 g (100.0 mmol) of pyridine and 20 ml of chloroform ( A chloroform (30 ml) solution containing 50.0 mmol) was added dropwise for 30 minutes with ice-cooling and stirring. After completion of dropping, the mixture was further stirred at a bath temperature of 40 ° C. for 4 hours. After completion of the reaction, 50 ml of chloroform was added to dilute the reaction solution. Subsequently, after sequentially washing with 100 ml of 5% hydrochloric acid aqueous solution, 100 ml of saturated aqueous sodium hydrogen carbonate solution and 100 ml of saturated saline solution, it was dried over magnesium sulfate, filtered and concentrated under reduced pressure. The obtained solid was washed several times with hexane, filtered, and dried under reduced pressure at 80 ° C. to obtain 22.0 g of a tosylated product.

The measurement result of ¹ H-NMR of the obtained product is shown below.
¹ H-NMR (CDCl ₃ ) measurement result:
δ (ppm): 7.82 (d), 7.28 (d), 3.74-3.54 (bs), 3.41 (s), 2.40 (s)

1-2 [Synthesis of Organic Compound (x1)]
2.0.0 g (0.8 mmol) of 5.39 g (2.5 mmol) of a methoxypolyethylene glycol compound having a p-toluenesulfonyloxy group at the terminal synthesized above and branched polyethyleneimine (manufactured by Aldrich, molecular weight 25,000) Then, 0.07 g of potassium carbonate and 100 ml of N, N-dimethylacetamide were stirred at 100 ° C. for 6 hours under a nitrogen atmosphere. To the resulting reaction mixture, 300 ml of a mixed solution of ethyl acetate and hexane (V / V = 1/2) was added, and after vigorous stirring at room temperature, the solid product was filtered. The solid was repeatedly washed twice with 100 ml of a mixed solution of ethyl acetate and hexane (V / V = 1/2), then dried under reduced pressure, and a compound (x1) in which polyethylene glycol was bound to branched polyethyleneimine 24.4 g of a solid was obtained.

The measurement result of ¹ H-NMR of the obtained product is shown below.
¹ H-NMR (CDCl ₃ ) measurement result:
δ (ppm): 3.50 (s), 3.05 to 2.20 (m)

1-3 [Synthesis of Complex]
10.0 g of silver oxide was added to 138.8 g of an aqueous solution using 0.592 g of the compound (x1) obtained in 1-2, and the mixture was stirred at 25 ° C. for 30 minutes. Subsequently, when 46.0 g of dimethylethanolamine was gradually added with stirring, the reaction solution turned black-red and slightly exothermic, but was left as it was and stirred at 25 ° C. for 30 minutes. Thereafter, 15.2 g of a 10% ascorbic acid aqueous solution was gradually added with stirring. Stirring was further continued for 20 hours while maintaining the temperature to obtain a black-red dispersion.

  A mixed solvent of 200 ml of isopropyl alcohol and 200 ml of hexane was added to the dispersion obtained after completion of the reaction and stirred for 2 minutes, followed by centrifugal concentration at 3000 rpm for 5 minutes. After removing the supernatant, a mixed solvent of 50 ml of isopropyl alcohol and 50 ml of hexane was added to the precipitate and stirred for 2 minutes, followed by centrifugal concentration at 3000 rpm for 5 minutes. After removing the supernatant, a small amount of water was added to the precipitate and stirred, and then the organic solvent was removed under reduced pressure to obtain an aqueous concentrate of the complex of silver nanoparticles (Y) and the organic compound (x1). Obtained. Furthermore, water was added to the aqueous concentrate and dispersed uniformly to obtain a silver paste (p1) having a solid content of 30%. A homodisper (manufactured by Primics Co., Ltd.) was used for mixing and dispersing.

  The obtained complex was sampled, and the peak of the plasmon absorption spectrum was observed at 400 nm by measuring the visible absorption spectrum of the diluted solution, and the production of silver nanoparticles was confirmed. Moreover, spherical silver nanoparticles (average particle diameter: 17.5 nm) were confirmed by TEM observation. As a result of measuring the silver content in the solid using TG-DTA, it was 97.2%.

  The above aqueous concentrate is left to stand in a -40 ° C. freezer for one day to freeze, and this is treated with a freeze dryer (FDU-2200, manufactured by Tokyo Rika Kikai Co., Ltd.) for 24 hours. A flaky mass was obtained. From the DSC measurement of the flaky powder, an exothermic peak corresponding to the melting point appeared in the range of 100 ° C to 150 ° C.

Synthesis Example 2 Synthesis of Organic Compound (x2) and Synthesis of Complex Using the Same 2-1 [Synthesis of Monofunctional Epoxy Resin]
Bisphenol A type linear epoxy resin EPICLON AM-040-P (manufactured by DIC Corporation, epoxy equivalent 933) 18.7 g (20 m equivalent), 4-phenylphenol 1.28 g (7.5 mmol), 65% ethyltriphenyl acetate A phosphonium ethanol solution (0.26 ml, 0.12 mol%) and N, N-dimethylacetamide (50 ml) were mixed and reacted at 120 ° C. for 6 hours in a nitrogen atmosphere. After standing to cool, it was dropped into 150 ml of water, and the resulting precipitate was washed twice with methanol and then dried under reduced pressure at 60 ° C. to obtain a monofunctional epoxy resin. The yield of the obtained product was 19.6 g, and the yield was 98%.

¹ H-NMR measurement was performed, and as a result of considering the integration ratio of the epoxy group, 0.95 epoxy rings remained in one molecule of the bisphenol A type linear epoxy resin, and it was confirmed that the epoxy resin was a monofunctional epoxy resin.

The measurement result of ¹ H-NMR of the obtained monofunctional epoxy resin is shown below.
¹ H-NMR (CDCl ₃ ) measurement result:
δ (ppm): 7.55 to 6.75 (m), 4.40 to 3.90 (m), 3.33 (m), 2.89 (m), 2.73 (m), 1. 62 (s)

2-2 [Synthesis of organic compound (x2)]
A solution of the monofunctional epoxy resin obtained above (3.0 g, 1.5 mmol) and acetone (50 ml) in the compound (x1) 14.4 g (0.48 mmol) obtained in Synthesis Example 1-2, methanol 60 ml The solution was added and stirred at 60 ° C. for 2 hours under a nitrogen atmosphere. After completion of the reaction, the solvent was removed to obtain a compound (x2) formed by bonding polyethylene glycol and an epoxy resin to branched polyethyleneimine.

2-3 [Synthesis of complex]
When 23.0 g of dimethylethanolamine was gradually added to 77.0 g of an aqueous solution using 0.263 g of the compound (x2) obtained in 2-2 above while stirring, a slight heat was generated. Subsequently, when the reaction temperature was changed to 45 ° C. and gradually added to 5.0 g of silver nitrate, the reaction solution turned black-red. Thereafter, the reaction temperature was set to 50 ° C. and stirred for 4.5 hours to complete the reaction, and a black-red dispersion was obtained.

  A mixed solvent of 100 ml of isopropyl alcohol and 100 ml of hexane was added to the dispersion liquid after completion of the reaction obtained above and stirred for 2 minutes, followed by centrifugal concentration at 3000 rpm for 5 minutes. After removing the supernatant, a mixed solvent of 25 ml of isopropyl alcohol and 25 ml of hexane was added to the precipitate and stirred for 2 minutes, followed by centrifugal concentration at 3000 rpm for 5 minutes. After removing the supernatant, a small amount of water was added to the precipitate and stirred, and then the organic solvent was removed under reduced pressure to obtain an aqueous concentrate of a complex of silver nanoparticles (Y) and compound (x2). . Furthermore, water was added to the aqueous concentrate and dispersed uniformly using a homodisper to obtain a silver paste (p2) having a solid content of 30%.

  The obtained complex was sampled, and a peak of a plasmon absorption spectrum was observed near 400 nm by measuring a visible absorption spectrum of the diluted solution, and the production of silver nanoparticles was confirmed. Moreover, spherical silver nanoparticles (average particle diameter 18.8 nm) were confirmed by TEM measurement. Moreover, as a result of measuring the silver content in solid using TG-DTA, 96.6% was shown.

Example 1
Apply the silver paste (p1) obtained in Synthesis Example 1 to a square copper plate (S1) using a stainless spatula and leave it at room temperature (25 ° C) for 30 minutes. After being dried with a hot press, it is placed on a copper plate (S2) of 30 mm × 40 mm and a thickness of 0.5 mm so that the coated surface is sandwiched, and is pressed at 180 ° C. and 2.5 MPa for 5 minutes. A joined body was obtained. After allowing the joined body to cool to room temperature, a cellophane tape (manufactured by Nichiban Co., Ltd.) is attached to the copper plate (S1), the copper plate (S2) is fixed, and after 1 minute, the cellophane tape is peeled off. As a result, it was confirmed that the cellophane tape was peeled off from the copper plate (S1), and the copper plate (S1) was firmly joined to the copper plate (S2).

Example 2
In Example 1, instead of using the silver paste (p1) as it is, a dispersion prepared by adding a 5% nitric acid aqueous solution to the silver paste (p1) and adjusting the pH to 5.5 was used, and the heating temperature was set to 150 ° C. In the same manner as in Example 1, the copper plates were joined together to obtain a joined body. A peel test using the same cellophane tape as in Example 1 was performed on the joined body. It was confirmed that peeling occurred between the cellophane tape and the copper plate, and no peeling occurred at the joint.

Example 3
A joined body was obtained in the same manner as in Example 2 except that the temperature of hot pressing was set to 120 ° C. in Example 2. As a result of performing the same peel test as in Example 1 on this joined body, it was confirmed that peeling occurred between the cellophane tape and the copper plate, and no peeling occurred at the joint.

Example 4
In Example 1, instead of the silver paste (p1), the powder obtained by pulverizing the flake-shaped lump after freeze-drying obtained in Synthesis Example 1 was used as a bonding material as it was, and the powdery form was used as a contact portion between the copper plates. A joined body was obtained in the same manner as in Example 1 except that the joining material was placed and dried at room temperature, and the joining conditions in the hot press were 250 ° C., 1.0 MPa, and 5 minutes. As a result of performing the same peel test as in Example 1 on this joined body, it was confirmed that peeling occurred between the cellophane tape and the copper plate, and no peeling occurred at the joint.

Example 5
A joined body was obtained in the same manner as in Example 3, except that a polyethylene terephthalate (PET) film (Toyobo Ester Film, Toyobo Co., Ltd.) was used instead of the copper plate (S1) in Example 2. As a result of performing a peeling test on the bonded body, it was confirmed that peeling occurred between the cellophane tape and the copper plate, and peeling did not occur at the bonded portion.

Example 6
A joined body was obtained in the same manner as in Example 2 except that a polyimide (PI) film (Kapton film, Toray DuPont Co., Ltd.) was used instead of the copper plate (S1) in Example 2. As a result of performing a peeling test on the bonded body, it was confirmed that peeling occurred between the cellophane tape and the copper plate, and peeling did not occur at the bonded portion.

Example 7
In Example 2, the silver paste (p2) obtained in Synthesis Example 2 was used instead of the silver paste (p1) obtained in Synthesis Example 1, and a PET film was used instead of the copper plate (S1). In the same manner as in Example 2, a joined body was obtained. As a result of performing a peeling test on the bonded body, it was confirmed that peeling occurred between the cellophane tape and the copper plate, and peeling did not occur at the bonded portion.

Example 8
A dispersion prepared by adding 5% nitric acid aqueous solution to the silver paste (p1) obtained in Synthesis Example 1 to pH 5.5 was applied on a copper plate using a stainless spatula, and a copper wire having a diameter of 20 μm was placed on the coated surface. After drying by standing at room temperature for 30 minutes, the joined body was obtained by heating in an oven at 150 ° C. for 30 minutes. After allowing this bonded body to cool to room temperature, a cellophane tape was applied from above the copper wire and peeled off after 1 minute, but the copper wire was not peeled off from the copper plate. The resistance value between the copper plate and the copper wire was 270 mΩ (using a low resistivity meter Loresta EP, manufactured by Mitsubishi Chemical Corporation).

Example 9
In 1-2 of Synthesis Example 1 [Synthesis of organic compound (x1)], the methoxypolyethylene glycol compound having a p-toluenesulfonyloxy group at the terminal synthesized in 1-1 was replaced with 5.39 g (2.5 mmol). The same procedure as in Example 1-2 except that the amount was 17.2 g (8.0 mmol) was performed to synthesize 35.7 g of a compound (x3) in which polyethylene glycol was bonded to a branched polyethyleneimine.

  In Example 1, 0.03 g of the compound (x3) obtained above was added to 10.0 g (solid content: 3.0 g) of silver paste (p1) instead of the silver paste (p1), and room temperature (25 ° C. ) Was used in the same manner as in Example 1 except that the dispersion after stirring for 1 hour was used and the heating temperature was further set to 180 ° C. As a result of performing a peeling test on the bonded body, it was confirmed that peeling occurred between the cellophane tape and the copper plate, and peeling did not occur at the bonded portion.

Example 10
After forming zinc oxide with a tablet molding machine, a tablet annealed at 500 ° C. was obtained. A joined body was obtained in the same manner as in Example 2, except that the zinc oxide tablet was used instead of the copper plate (S1) in Example 2. As a result of performing a peeling test on the bonded body, it was confirmed that peeling occurred between the cellophane tape and the copper plate, and peeling did not occur at the bonded portion.

Reference example (dispersibility evaluation of composite and storage stability test of silver paste)
The storage stability of the silver pastes (p1) and (p2) obtained in Synthesis Examples 1 and 2, the paste after pH adjustment in Examples 2 and 8, and the paste prepared in Example 9 were evaluated. As a specific method of the evaluation method, the non-volatile component ratio at 130 ° C. for 30 minutes immediately after preparation was measured in advance. After standing at 5 ° C. for 1 week, the sample was gently sampled from near the liquid surface of the dispersion, and the nonvolatile component ratio was measured in the same manner. When the non-volatile component ratio immediately after the preparation is set to 100, the ratio of the non-volatile component ratio near the liquid surface after 1 week is defined as the non-volatile component concentration retention ratio of the upper layer portion of the dispersion, and the storage stability evaluation did. As a result, the silver paste (p1) obtained in Synthesis Example 1 was 96%, the silver paste (p2) obtained in Synthesis Example 2 was 94%, the pH-adjusted paste obtained in Example 2 was 89%, The paste after pH adjustment obtained in Example 8 was 91%. All silver pastes had good storage stability. In addition, the storage stability of the dispersion after addition of the compound (x3) obtained in Example 9 was 98%.

  Regarding the dispersibility of the composite, the mirror material of the coating film after applying and drying the bonding material on the copper plates in Examples 1, 2, 7, 8 and 9 was visually judged to be bright (◯), normal ( (Triangle | delta), When it evaluated as inferior (x), it was all good ((circle)) mirror surface coating-film surface.

Comparative Example 1
10.0 g of silver oxide was added to 138.8 g of an aqueous solution using 0.592 g of a commercially available polymer dispersant (Dispervic 180 manufactured by Big Chemie), and the mixture was stirred at 25 ° C. for 30 minutes. Subsequently, when 46.0 g of dimethylethanolamine was gradually added with stirring, the reaction solution turned black-red and slightly exothermic, but was left as it was and stirred at 25 ° C. for 30 minutes. Thereafter, 15.2 g of a 10% ascorbic acid aqueous solution was gradually added with stirring. Stirring was further continued for 20 hours while maintaining the temperature to obtain a black-red dispersion.

  A mixed solvent of 200 ml of isopropyl alcohol and 200 ml of hexane was added to the dispersion obtained after completion of the reaction and stirred for 2 minutes, followed by centrifugal concentration at 3000 rpm for 5 minutes. After removing the supernatant, a mixed solvent of 50 ml of isopropyl alcohol and 50 ml of hexane was added to the precipitate and stirred for 2 minutes, followed by centrifugal concentration at 3000 rpm for 5 minutes. After removing the supernatant, after adding a small amount of water to the precipitate and stirring, the organic solvent was removed under reduced pressure to obtain an aqueous concentrate of a composite of silver nanoparticles and a commercially available polymer dispersant. . Furthermore, water was added to the aqueous concentrate and dispersed uniformly using a homodisper to obtain a silver paste (p′1) having a solid content of 30%.

  The obtained complex was sampled, and the peak of the plasmon absorption spectrum was observed at 400 nm by measuring the visible absorption spectrum of the diluted solution, and the production of silver nanoparticles was confirmed. Further, spherical silver nanoparticles (average particle diameter: 30.5 nm) were confirmed by TEM observation. As a result of measuring the silver content in the solid using TG-DTA, it was 92.2%.

  In Example 2, a joined body was obtained in the same manner as in Example 2 except that the silver paste (p′1) obtained above was used instead of the silver paste (p1). As a result of performing a peeling test on this bonded body, it was confirmed that peeling occurred between the copper plates, and the bonding strength at the bonded portion was inferior to the adhesive strength of the cellophane tape.

  The bonding method of the present invention is a thin display, electronic paper, electronic book, and tag that are under development in response to downsizing, lightening, thinning, environmental problems, etc. of all electronic products for which significant future growth is expected. It can be suitably used for solar cell panels and the like. In particular, it can be used with materials that are not thermally resistant to high temperatures, and can be used without problems even under high temperature conditions, so it is possible to simplify the complicated joining process, which is advantageous in terms of cost. .

Claims (8)

A method for producing a joined body for joining members to be joined using a joining material containing an organic compound (X) and silver nanoparticles (Y),
The objects to be joined are metal or metal oxide,
As a bonding material, the organic compound (X) is bonded with polyethylene glycol (b) having a number average molecular weight of 500 to 5,000 to an amino group in polyethyleneimine (a) having a number average molecular weight of 500 to 50,000. An organic compound (x1), or an amino group in a polyethyleneimine (a) having a number average molecular weight of 500 to 50,000, a polyethylene glycol (b) having a number average molecular weight of 500 to 5,000, and a linear group An organic compound (x2) formed by bonding with an epoxy resin (c),
Further, using a bonding material containing a compound (Z) having a functional group capable of reacting with a nitrogen atom in the polyethyleneimine (a), and
A method for producing a joined body, comprising: providing a layer of the joining material between joining parts of an object to be joined, and then joining the layer by heating at a temperature of 100 to 250 ° C. The method according to claim 1, wherein the compound (Z) is an inorganic acid . The manufacturing method according to claim 1 or 2, wherein pressurization is further performed in the range of 10 kPa to 10 MPa at the time of joining. The manufacturing method according to claim 1, wherein the bonding material has a melting point in a dry state of 100 to 150 ° C. 5. The manufacturing method according to claim 1, wherein the bonding material is powder or paste. The manufacturing method according to claim 1, wherein the bonding material further contains a hydrophilic polymer. The hydrophilic polymer is at least one polymer selected from the group consisting of polyethylene glycol, polyethyleneimine, polyvinyl alcohol, amino (meth) acrylate, polyvinyl pyrrolidone, polyoxazoline, and copolymers of these polymers. The manufacturing method as described. A joined body obtained by the manufacturing method according to claim 1.