JP5306322B2 - Composite silver nanopaste, manufacturing method thereof, bonding method and pattern forming method - Google Patents

Description

  The present invention relates to a paste composed of composite silver nanoparticles in which an organic coating layer made of an organic substance is formed around a silver nucleus made of a large number of silver atoms. More specifically, the paste is applied and fired. The present invention relates to a composite silver nanopaste in which the organic coating layer and other organic components are diffused to form a silver film, and a semiconductor junction and an electrode pattern are formed from the silver film, a manufacturing method thereof, a bonding method, and a pattern formation method.

  In general, semiconductors, electronic circuits, electronic devices, and the like secure various electrical components by melting and fixing them to a substrate with solder. However, the conventional solder is an alloy of Sn and Pb, and the use of Pb is being prohibited as a recent environmental preservation measure. Therefore, development of a Pb-free alternative solder that replaces the conventional solder is desired.

  As a characteristic of the alternative solder, it is natural that Pb is not contained, but there are other demands for high thermal conductivity, low melting point, high electrical conductivity and high safety. Silver has attracted attention as a material that meets this expectation, and composite silver nanoparticles have been developed as ultrafine particles.

  First, as patent document 1, Japanese Patent No. 3205793 was published. Silver organic compounds (especially silver organic complexes) were selected as starting materials. The silver organic compound is heated at a temperature higher than or equal to the decomposition start temperature and lower than the complete decomposition temperature in an inert gas atmosphere in which air is shut off, and the coating layer of the silver organic compound is formed around the decomposed and reduced silver core. Composite silver nanoparticles were produced. The particle size of the silver nuclei is 1 to 100 nm, and is therefore commonly referred to as composite silver nanoparticles. Specifically, when 100 g of silver stearate was heated at 250 ° C. for 4 hours in a flask under a nitrogen stream, composite silver nanoparticles having a silver nucleus with a particle size of 5 nm were generated.

  In the manufacturing method, since silver stearate is heated by a solid phase method without a solvent, even if the silver nuclei of the generated composite silver nanoparticles are 5 nm, a large number of composite silver nanoparticles are bound in a dumpling state. There is a drawback of becoming large secondary particles. In addition, since silver stearate is used as a starting material, a stearic acid group having 17 carbon atoms around the silver core becomes an organic coating layer, which has the disadvantage that the silver content is reduced.

  Therefore, WO00 / 076699 is disclosed as Patent Document 2. The inventor is one of the inventors of this international publication. A plurality of inventions are disclosed in this publication, and among them, a method of treating a metal inorganic compound with a surfactant is important. That is, a first step of colloiding a metal inorganic compound with a surfactant in a non-aqueous solvent to form an ultrafine particle precursor, and a reducing agent is added to the colloidal solution to reduce the ultrafine particle precursor. And a second step of generating composite metal nanoparticles in which a surfactant shell is formed as a coating layer on the outer periphery of the metal core.

  In the above method, since the metal inorganic compound is dissolved in the non-aqueous solvent, the generated composite metal nanoparticles are dispersed in the non-aqueous solvent and are difficult to be in a dumpling state. However, since the added surfactant has a large number of carbon atoms, the number of carbon atoms in the surfactant shell, which is an organic coating layer, is naturally large, and the temperature at which the surfactant shell is baked to disperse, that is, the firing temperature is increased. was there.

  Under such circumstances, research on composite silver nanoparticles has progressed, and WO 01/070435 has been published as Patent Document 3. In this publication, it is described that composite silver nanoparticles are made from silver carbonate and myristic acid (C number is 14). Further, it is described that composite silver nanoparticles were produced from silver carbonate and stearyl alcohol (C number is 18). However, since myristic acid (C number is 14) and stearyl alcohol (C number is 18) have a large carbon number, it goes without saying that there is a disadvantage that the firing temperature for silvering becomes high.

Japanese Patent No. 3205793 WO00 / 076699 WO01 / 070435 Japanese Patent No. 3638486 Japanese Patent No. 3638487 Ph. Buffat and J-P. Borel, Phy. Rev. A13 (1976) 2287

  In order to lower the silvering temperature, the present inventors react silver carbonate and C1-C9 or C11 alcohol to produce silver alkoxide-type composite silver nanoparticles composed of alcohol residues around the silver nucleus. Succeeded.

  The C1-C9 or C11 composite silver nanoparticles obtained in this way naturally have a lower silverization temperature than the C14 or C18 composite silver nanoparticles obtained in Patent Document 3. As a result of the decrease in the number of carbon atoms, there is an advantage that the silver content increases while the silvering temperature decreases.

  Therefore, the present inventors decided to produce a paste using the composite silver nanoparticles of C1 to C9 or C11. This paste is used to assemble the electronic parts by joining the materials, or to test the formation of the electrode pattern on the substrate to confirm the effectiveness of the paste. Regarding the bonding method using paste, there are the following two conventional patent publications.

  As Patent Literature 4, Japanese Patent No. 3638486 is disclosed. Here, composite metal ultrafine particles in which the periphery of a core portion substantially composed of a metal component having an average particle diameter of 1 to 10 nm is coated with a coating layer composed of an organic substance having 5 or more carbon atoms are prepared in advance, and the composite Preparing a metal paste by dispersing metal ultrafine particles in a solvent, attaching the metal paste onto a terminal electrode of a circuit board to form a metal paste ball mainly composed of composite metal ultrafine particles, and the metal There are described a step of bonding electrodes of a semiconductor element on a paste ball using a face-down method and a step of electrically connecting the semiconductor element and a circuit board by low-temperature firing.

  Japanese Patent No. 3638487 is disclosed as Patent Document 5. In this patent publication, composite metal ultrafine particles in which the periphery of a core portion substantially composed of a metal component having an average particle diameter of 1 to 10 nm is coated with a coating layer composed of an organic substance having 5 or more carbon atoms is prepared in advance. A step of preparing a metal paste by dispersing the composite metal ultrafine particles in a solvent, a step of depositing the metal paste on an electrode of a semiconductor element and firing at a low temperature to produce an ultrafine particle electrode, A process of forming a solder bump and a process of heat-sealing the solder bump to a terminal electrode of a circuit board are disclosed.

  Patent Documents 4 and 5 describe that composite metal ultrafine particles are dispersed in a solvent to prepare a metal paste. In particular, claim 3 of Patent Document 4 includes a metal having high conductivity in addition to a solvent. A metal paste to which a resin component is added is described. In both documents, only toluene is exemplified as a solvent, and the roles of Patent Documents 4 and 5 are imparted with a role of reducing the viscosity to make the paste into a solution. The resin component is added to increase the viscosity, and an appropriate amount of solvent and resin component is added to produce a paste having a predetermined viscosity.

  According to Patent Documents 4 and 5, the present inventor also prepared a paste by dissolving the above-mentioned C1-C9 or C11 composite silver nanoparticles in toluene. The paste was prepared to have a viscosity that allowed it to flow naturally when tilted at room temperature so that it could be easily applied to a substrate or semiconductor electrode. The paste was stored in a container at room temperature for only 2 weeks. After storage for 2 weeks, a paste film having a thickness of 1 μm was formed on the circuit board by screen printing, and baked in an electric furnace at 350 ° C. for 20 minutes to form the paste film into a silver film.

  The surface and cross section of the silver film were observed using an optical microscope and an electron microscope. As a result, some irregularities were found on the surface of the silver film. In the baking at 350 ° C., all organic substances are diffused, but the silver nuclei are not melted, but the surface is melted and the silver nuclei are sintered to form a silver film. Therefore, if the silver nuclei are large, the surface irregularities will be amplified. That is, it was considered that the unevenness on the surface was formed by sintering between large silver nuclei. The reason for the formation of large silver nuclei is considered to be the result of composite silver nanoparticles agglomerating with each other in the paste to form secondary particles during storage for 2 weeks. When a dispersant or a surfactant is added to the paste to prevent agglomeration, the silver content in the paste decreases, and the surfactant does not completely dissipate at 350 ° C., and organic substances are not present in the silver film. There is also a situation that remains. Therefore, it is necessary to avoid adding extra organic matter to the paste as much as possible as long as low temperature firing is considered.

  Since the composite silver nanoparticles may have aggregated before the addition of the solvent, the composite silver nanoparticles were finely ground and monodispersed in advance in a mortar, and then the solvent was added to prepare a paste. After leaving this paste for 2 weeks, a paste film was formed on the circuit board and baked at 350 ° C. for 20 minutes. When observed with an electron microscope, the irregularities on the surface of the silver film were somewhat improved, but the irregularities still remained.

  From the above results, when the composite silver nanoparticles are mixed with a solvent and stored in a fluidized state, the composite silver nanoparticles agglomerate into secondary particles, and the particle size of the secondary particles increases as the storage time increases. The conclusion is reached that increases. The result is that the composite silver nanoparticles are added to a solvent such as toluene having a small viscosity to form a fluid paste having fluidity at room temperature, and the fluid paste is mass-produced and stored for a long period of time. The problem was highlighted.

  Accordingly, an object of the present invention is to provide a technology for pasting C1-C9 or C11 composite silver nanoparticles in a form that does not agglomerate, that is, a non-aggregating paste, and realizing the non-aggregating property with a non-flowable resin. It is to provide a non-flowable paste. Moreover, it is providing the manufacturing method of the non-fluid paste, and also providing the joining method and pattern formation method using a non-fluid paste simultaneously.

  The present invention has been made to solve the above-mentioned problems, and the first embodiment of the present invention has 1 to 9 carbon atoms around silver nuclei having an average particle diameter of 1 to 20 nm composed of an aggregate of silver atoms. 11 composed of a metal component containing at least composite silver nanoparticles formed with an organic coating layer composed of at least one alcohol molecule residue, alcohol molecule derivative or alcohol molecule, and the resin is at 10 ° C. or less. It is a composite silver nanopaste that is in a non-flowing state, holds the metal component in a dispersed state, and is fluidized by heating so that it can be applied.

  A second aspect of the present invention is a composite silver nanopaste according to the first aspect, wherein the composite silver nanoparticles are 95 (mass%) or less and the resin is 20 (mass%) or less.

  A third aspect of the present invention is a composite silver nanopaste according to the first aspect, wherein silver fine particles having an average particle diameter of 0.1 to 10 μm are added as the metal component.

  According to a fourth aspect of the present invention, in the third aspect, the composite silver nanoparticles are 5 to 85 (mass%), the silver fine particles are 80 to 10 (mass%), and the resin is 20 (mass%). The composite silver nanopaste is as follows.

  A fifth aspect of the present invention is a composite silver nanopaste according to any one of the first to fourth aspects, wherein a desired amount of a solvent is added to make it flowable even at 10 ° C. or less and can be applied.

  In the sixth embodiment of the present invention, a resin that is in a non-flowing state at 10 ° C. and fluidized by heating has a carbon number of 1 to 9 or 11 around silver nuclei having an average particle diameter of 1 to 20 nm composed of aggregates of silver atoms. A composite silver nanoparticle formed with an organic coating layer composed of one or more of alcohol molecule residues, alcohol molecule derivatives or alcohol molecules, and if necessary, silver fine particles are mixed as a metal component, and the resin is fluidized under heating to make the whole Is cooled to a temperature at which the resin becomes non-flowing after kneading, and the metal component is kept in a dispersed state in the resin.

  A seventh aspect of the present invention is a method for producing a composite silver nanopaste according to the sixth aspect, wherein the silver nuclei have an average particle diameter of 1 to 20 nm and the silver fine particles have an average particle diameter of 0.1 to 10 μm.

  An eighth aspect of the present invention is a method for producing a composite silver nanopaste according to the sixth or seventh aspect, wherein a desired amount of solvent is added to make a paste that can be applied by being fluidized even at 10 ° C. or lower. .

  According to a ninth aspect of the present invention, a composite silver nanopaste according to any one of the first to fifth aspects is prepared, and the composite silver nanopaste is applied to a lower body to form a paste layer, and the paste layer is formed on the paste layer. In this joining method, the upper body is placed, the paste layer is silvered by heating, and the lower body and the upper body are joined.

  In a tenth aspect of the present invention, a composite silver nanopaste according to any one of the first to fifth aspects is prepared, and the composite silver nanopaste is applied to a predetermined pattern on a surface of a substrate to form a paste pattern. And a pattern forming method in which the paste pattern is silvered by heating to form a silver pattern.

According to the first embodiment of the present invention, an alcohol molecule residue, an alcohol molecule derivative or an alcohol molecule having 1 to 9 or 11 carbon atoms is disposed around a silver nucleus having an average particle diameter of 1 to 20 nm composed of an aggregate of silver atoms. Since composite silver nanoparticles formed with one or more organic coating layers are used, an inexpensive composite silver nanopaste can be provided. Since the composite silver nanoparticles start with cheap C1-C9 or C11 alcohol and a relatively cheap silver salt (for example, silver carbonate), inexpensive composite silver nanoparticles can be used. Moreover, the C1 to C9 alcohols are characterized by a relatively small number of carbon atoms and a relatively high silver content in the composite silver nanoparticles compared to the C10 and C12 alcohols. Moreover, since C11 has a carbon number smaller than C12, silver content rate is higher than C12. Hereinafter, the composite silver nanoparticles may be written as CnAgAL (n = 1 to 9, 11), or may be written as C1AgAL to C9AgAL, C11AgAL. The meaning is silver alkoxide type composite silver nanoparticles having 1 to 9 or 11 carbon atoms. C1 is methanol, C2 is ethanol, C3 is propanol, C4 is butanol, C5 is pentanol, C6 is hexanol, C7 is heptanol, C8 is octanol, C9 is nonanol, and C11 is unidecanol. That is, the composite silver nanoparticle which has the organic coating layer which consists of many Cn alkoxide groups around the silver nucleus which is an aggregate | assembly of a silver atom is written as CnAgAL. The alcohol residue is a concept including, for example, an alkoxide group C _n H _{2n + 1} O when the alcohol is written as C _n H _{2n + 1} OH. The alcohol derivative is a concept including, for example, C _n-1 H _2n-1 CHO, C _n-1 H _2n-1 COOH, C _n-1 H _2n-1 COO, and the like. Alcohol refers to C _n H _{2n + 1} OH itself.

The characteristic of the composite silver nanopaste according to the present invention is the greatest characteristic in the function of the resin. The resin is in a non-flowing state at 10 ° C. or lower, and has a property of holding the composite silver nanoparticles and the silver fine particles in a dispersed state and fluidizing by heating. The non-flowing state means a solid state or a high-viscosity state, and refers to a property of holding the composite silver nanoparticles and the silver fine particles fixedly in a dispersed state. 10 degrees C or less is a temperature range which carries out low temperature storage in a refrigerator, and the said 10 degrees C or less can be achieved by long-term storage by refrigerator storage. Thus, when storing in a refrigerator, the paste is in a non-flowing state, and the composite silver nanoparticles and silver fine particles dispersed therein are fixed in the paste by the resin and cannot be aggregated with each other. Therefore, at 10 ° C. or lower, the particles cannot be aggregated with each other, and the particles are completely prevented from aggregating and forming a dump during storage of the paste. This non-flowable paste can be referred to as a non-cohesive paste. However, for example, when heated to 40 ° C. or higher, the resin is liquefied or the viscosity is suddenly lowered to be in a fluid state, and can be applied to an object as a paste. Accordingly, after the paste of the present invention is produced, it is stored at 10 ° C. or less and non-aggregated (non-fluidized). Just before applying the paste to the object, it is heated and fluidized to make a fluid paste, and if this fluid paste is applied to the object, the metal (silver) is not agglomerated so it is extremely dense. A silver film can be formed. If the remaining fluid paste is immediately cooled to 10 ° C. or less, it can be stored for a long time as a non-aggregating paste. Examples of the resin that changes from a high viscosity to a low viscosity by heating include isobornylcyclohexanol (referred to as rosin) and glycerin (referred to as syrup). Since the melting point of glycerin is 17 ° C., solidification is possible if it is set to 10 ° C. or lower in a dry state. As resins that are solid at 10 ° C. or lower and liquefy when heated, alcohols such as myristyl alcohol (C14), palmityl alcohol (C16), stearyl alcohol (C18), and behenyl alcohol (C22), and other substances can be used. These resins must have the property that all components are diffused when baked or there are very few residues such as carbides, and due to this property the electrical conductivity of the silver film formed by calcination And thermal conductivity can be greatly improved.
Accordingly, the resin of the present invention is not a resin having a normal chemical concept, but is a generic term for substances that exhibit non-fluidity at 10 ° C., and is a substance in which everything is diffused by firing and residues such as carbides do not appear. Means.

  In a normal paste, a dispersant is added to disperse the composite silver nanoparticles, or a surfactant is added. However, when these impurity organic substances are added, not only the silver content is lowered, but also when fired, A large amount of gas is generated from the impurity organic substance, and a large amount of voids (bubble voids) are formed in the silver film by this gas. At the same time, the electrical conductivity is lowered and the bonding force with the substrate is lowered. Bonding performance is reduced. On the other hand, since organic substances other than resin are not added in the present invention, the silver content can be kept high, and at the same time, the amount of generated gas is small, the number of voids is inevitably reduced, the increase in bonding force and electrical conductivity and There is an effect that the thermal conductivity can be increased.

  According to the 2nd form of this invention, the said composite silver nanoparticle is 95 (mass%) or less, The composite silver nanopaste whose said resin is 20 (mass%) or less is provided. The simplest paste composition is a mixture of composite silver nanoparticles and resin. In this case, the silver component is only composite silver nanoparticles, the maximum mass% is 95 mass%, and the minimum mass% of the resin is 5 mass%. What is necessary is just to increase the mass% of resin according to the fall of the mass% of a composite silver nanoparticle. However, since the silver content in the paste is preferably 80 mass% or more, the mass% of the resin is preferably set to 20 mass% or less.

  According to the 3rd form of this invention, it is a composite silver nanopaste to which silver fine particles with an average particle diameter of 0.1-10 micrometers are added as said metal component. In this embodiment, silver fine particles are added as the silver component in addition to the composite silver nanoparticles. Since the silver fine particles are pure silver and do not contain any organic matter, the silver content in the paste can be increased by adding silver fine particles. Since the particle diameter of the silver fine particles is 0.1 to 10 μm and the silver core particle diameter of the composite silver nanoparticles is 1 to 20 nm, the composite silver nanoparticles are considered to play a role of an adhesive between the silver fine particles. It is done. The composite silver nanoparticles adhere to the surface of the silver fine particles, the organic components are diffused by firing, and the silver fine particles whose surfaces are melted are bonded to each other. In other words, when the composite silver nanoparticles accumulate in the gaps between the large silver fine particles, and the organic matter is diffused by firing, the gaps between the silver fine particles are filled with silver nuclei, and the silver fine particles are Therefore, the silver film itself is densely formed, and a conductor having high strength and high electrical conductivity is provided. When the particle size relationship is as described above, the silver nuclei fill the gaps between the silver fine particles, and the gas nuclei are filled back into the bubble cavities (voids), and the number of voids is reduced. As a result, it is possible to improve the bonding strength and electrical conductivity with the substrate.

  According to the fourth aspect of the present invention, the composite silver nanoparticles are 5 to 85 (mass%), the silver fine particles are 80 to 10 (mass%), and the resin is 20 (mass%) or less. A silver nanopaste is provided. In this case, the composition of the composite silver nanopaste is composite silver nanoparticles, silver fine particles, and a resin. The boundary of the composition ratio (mass%) is composite silver nanoparticle: silver fine particle: resin = 85: 10: 5 to 5:80:15, but composite silver nanopastes having various composition ratios within the above range are used. Composed. The composite silver nanoparticles are 5 to 85 (mass%). When the composite silver nanoparticle is less than 5 mass%, the adhesion performance between the silver fine particles is lowered. When the composite silver nanoparticle is 85 mass% or more, the organic content in the paste becomes excessive. In addition, the silver fine particles are 80 to 10 (mass%). When the mass is 80 mass% or more, the content of the composite silver nanoparticles is reduced, the adhesiveness between the silver fine particles is lowered, and when the mass is 10 mass% or less, There is a weak point that the silver content of is reduced. Therefore, within the above range, preparing a composite silver nanopaste having an appropriate silver content, efficiently diffused during firing, and restricting the amount of voids (bubble removal) to an appropriate value Can do.

  According to the fifth aspect of the present invention, there is provided a composite silver nanopaste that can be applied by adding a desired amount of solvent to make it flowable even at 10 ° C. or lower. In the first form, a paste to which only a resin is added is provided, and even if the paste is stored at a temperature of 10 ° C. or lower for a long period of time, the paste does not have fluidity. Are immobilized and mutual aggregation does not occur. After being stored as a non-flowable paste for an appropriate period of time, immediately before joining the paste, the solvent of the fifth embodiment can be added and fluidized, and the flowable paste can be applied to the substrate by a dispenser. In order to fluidize the non-fluid paste, there are two methods: heating and adding a solvent. In the present embodiment in which a solvent is added, since the organic matter content in the paste increases, there is a weak point in which the amount of gas generated by firing increases and the amount of void generation increases. However, if a solvent is added immediately before coating, it is possible to avoid the composite silver nanoparticles from agglomerating into secondary particles (ie, dumpling). The solvent has a function of reducing the viscosity of the paste, and general organic solvents that evaporate at a relatively low temperature can be used. For example, C1-C8 alcohol, xylene, toluene, acetone, hexane, and other solvents can be used.

  According to the sixth embodiment of the present invention, the resin that is in a non-flowing state at 10 ° C. and fluidized by heating has a carbon number of 1 to 9 around silver nuclei having an average particle diameter of 1 to 20 nm composed of an aggregate of silver atoms. Or a composite silver nanoparticle formed with an organic coating layer composed of at least one alcohol molecule residue, alcohol molecule derivative or alcohol molecule, and optionally silver fine particles as a metal component, and fluidizing the resin under heating. Thus, there is provided a method for producing a composite silver nanopaste in which the whole is kneaded and cooled to a temperature at which the resin becomes non-flowing after kneading to hold the metal component in a dispersed state in the resin. As described above, the resin is in a non-flowing state at 10 ° C. and has a characteristic of being fluidized by heating. Among them, heating is not only heating by a heating means, but also friction during kneading releases frictional heat, so friction is included in one form of heating. There are three methods for kneading. First, simultaneous mixing of resin, composite silver nanoparticles and silver fine particles, second, two-stage kneading in which resin and composite silver nanoparticles are kneaded and then silver fine particles are added and kneaded; There is a two-stage kneading in which a composite silver nanoparticle is added and kneaded after kneading a resin and silver fine particles. When silver fine particles are not added, there is only a form of kneading the resin and composite silver nanoparticles. In any case, the paste fluidized by heat kneading is cooled to be non-fluidized and stored as a non-fluidized paste. Therefore, in non-fluid storage, composite silver nanoparticles and silver fine particles are not aggregated in the paste.

  According to the 7th form of this invention, the manufacturing method of the composite silver nanopaste whose average particle diameter of the said silver nucleus is 1-20 nm and whose average particle diameter of the said silver fine particle is 0.1-10 micrometers is provided. By adding silver fine particles, the silver content in the paste can be increased. Since the particle diameter of the silver fine particles is 0.1 to 10 μm and the silver core particle diameter of the composite silver nanoparticles is 1 to 20 nm, when the paste is fired, the composite silver nanoparticles are between the silver fine particles. It is thought to play the role of an adhesive. The composite silver nanoparticles adhere to the surface of the silver fine particles, the organic components are diffused by firing, and the silver fine particles whose surfaces are melted are bonded to each other. In other words, when the paste is applied, the composite silver nanoparticles accumulate in the gaps between the large silver fine particles, and when the organic matter is diffused by firing, the gaps between the silver fine particles are filled with silver nuclei, Since the silver fine particles are bonded to each other by the silver nuclei, the silver film itself is densely formed, and a silver conductor having high strength and high electrical conductivity is provided. When the particle size relationship is as described above, the silver nuclei fill the gaps between the silver fine particles, and the gas nuclei are filled back into the bubble cavities (voids), and the number of voids is reduced. As a result, it is possible to improve the bonding strength and electrical conductivity with the substrate.

  According to the 8th form of this invention, the manufacturing method of the composite silver nano paste which adds a desired amount of solvent and makes it a fluid state even if it is 10 degrees C or less to make a paste which can be applied is provided. When no solvent is added, the composite silver nanopaste of the present invention is in a non-flowing state at a low temperature. In order to fluidize this non-flowable paste, there are a case where the temperature is raised by heating and a case where a solvent is added. In this embodiment, a method for producing a paste that is in a fluid state even at 10 ° C. is provided by adding a solvent to the production method of the sixth embodiment or the seventh embodiment. The solvent has a function of reducing the viscosity of the paste, and general organic solvents that evaporate at a relatively low temperature can be used. For example, C1-C8 alcohol, xylene, toluene, acetone, hexane, and other solvents can be used. In particular, since the organic coating layer of the composite silver nanoparticles of the present invention is an alcohol-derived substance, alcohol is advantageous as a solvent.

  According to the ninth aspect of the present invention, the composite silver nanopaste of the present invention is prepared, the composite silver nanopaste is applied to the lower body to form a paste layer, and the upper body is disposed on the paste layer, There is provided a joining method in which the paste layer is silvered by heating to join the lower body and the upper body. This embodiment is a method for joining two objects using the composite silver nanopaste according to the present invention, in which one object is referred to as a lower body and the other object is referred to as an upper body, and both are bonded via a paste layer and fired. Thus, strong bonding can be achieved by silvering the paste layer. Moreover, since the silver film is excellent in electrical conductivity and thermal conductivity and can be fired at a low temperature, it is possible to join low melting point objects.

  According to the tenth aspect of the present invention, the composite silver nanopaste of the present invention is prepared, the composite silver nanopaste is coated on the surface of the substrate in a predetermined pattern, and the paste pattern is formed by heating. A pattern forming method is provided in which a silver pattern is formed by silveration. For example, when a silver film having a predetermined pattern is formed on a resin substrate having a low melting point, a method for forming a silver film having various patterns on various materials at a low temperature is provided according to the embodiment of the present invention.

FIG. 1 is a production process diagram of composite silver nanoparticles CnAgAL. FIG. 2 is a first process diagram of a formation reaction of composite silver nanoparticles. FIG. 3 is a second process diagram of the formation reaction of composite silver nanoparticles. FIG. 4 is a high-resolution transmission electron microscope view of C2AgAL. FIG. 5 is a high-resolution transmission electron microscope view of C4AgAL. FIG. 6 is a thermal analysis diagram of C2AgAL. FIG. 7 is a thermal analysis diagram of C4AgAL. FIG. 8 is a production process diagram of a composite silver nanopaste. FIG. 9 is a characteristic diagram of the viscosity and temperature of IBCH. FIG. 10 is a thermal analysis diagram of IBCH with a heating rate of 3 ° C./min. FIG. 11 is a graph showing the relationship between the evaporation temperature of IBCH and the temperature rise rate. FIG. 12 is a characteristic diagram of viscosity and temperature of glycerin. FIG. 13 is a thermal analysis diagram of the composite silver nanopaste (C2AgAL) in the atmosphere. FIG. 14 is a thermal analysis diagram of the composite silver nanopaste (C4AgAL) in the atmosphere. FIG. 15 is a thermal analysis diagram of the composite silver nanopaste (C6AgAL) in the atmosphere.

  Hereinafter, embodiments of a composite silver nanopaste, a manufacturing method, a bonding method, and a pattern forming method according to the present invention will be described in detail with reference to the drawings and tables.

Table 1 is a list of molar ratios of the raw materials for production of the composite silver nanoparticles used in the present invention and the alcohol solution. An inorganic silver salt or an organic silver salt can be used as the silver raw material, and silver carbonate (Ag2CO3) is described as an example of the inorganic silver salt. As the alcohol starting _{material, C n H 2n + 1 OH} (n = 1~9,11) is used. As shown in Table 1, the number of moles of alcohol in which 100 g (0.363 mole) of silver carbonate fine particles are dispersed ranges from 3.63 mole to 23.2 mole, and the mole ratio (number of moles of alcohol / silver mole of silver carbonate). Number) is in the range of 10-63.9. Alcohol is added in excess of the stoichiometric ratio of silver carbonate and alcohol, and an excess alcohol solution is used to cause a chemical reaction. The reason is that the composite silver nanoparticles CnAgAL produced by chemical reaction have a very small silver core particle size of 1 to 20 nm, preventing collision of the composite silver nanoparticles in an alcohol solution, and forming secondary particles by aggregation. It is for suppressing. Ten types of composite silver nanoparticles are produced.

Table 2 is a list of molecular weights of raw materials for composite silver nanoparticles and the number of moles of 100 g. Specific names of alcohol (C _n H _{2n + 1} OH) are methanol (CH ₃ OH), ethanol (C ₂ H ₅ OH), propanol (C ₃ H ₇ OH), butanol (C ₄ H ₉ OH), pen ethanol _{(C 5} H 11 OH), hexanol _{(C 6} H 13 OH), heptanol _{(C 7} H 15 OH), octanol _{(C 8} H 17 OH), nonanol _{(C 9} H 19 OH), Unidekanoru _{(C 10} H ₂₁ OH). The boiling point BT (° C.) of the alcohol is also shown.

  FIG. 1 is a production process diagram of composite silver nanoparticles. A mixed solution of a predetermined amount of silver salt powder and a predetermined amount of alcohol is prepared, and the mixed solution is sealed in a reaction vessel. The mixed solution is heated at a generation temperature PT (° C.) for a predetermined time under an Ar gas flow. During this heating process, the silver salt and alcohol react to produce countless composite silver nanoparticles. The reaction time is preferably within 1 hour. When the reaction time is long, the composite silver nanoparticles start to aggregate with each other and become secondary particles. Therefore, it is desirable to cool rapidly after the reaction. Finally, the composite silver nanoparticles are recovered from the reaction solution as a powder. The composite silver nanoparticle is expressed as CnAgAL, which indicates that it is an alkoxide type composite silver nanoparticle. However, the alcohol used is the above 10 types, and n = 1 to 9 or 11.

FIG. 2 is a first process diagram of a formation reaction of composite silver nanoparticles according to the present invention. The raw material is silver salt (1) and alcohol C _n H _{2n + 1} OH (n = 1 to 9, 11) represented by formula (2). R _{n in the} formula (3) represents a hydrocarbon group C _n H _{2n + 1} of the alcohol. Carbon number n is limited to 10 types of 1-9 or 11. Many silver salt fine particles are insoluble in alcohol, and the hydrophilic group OH of alcohol has a property of easily bonding to the surface of the silver salt fine particles. The hydrophobic group R _n of the alcohol has a high affinity with alcohol solvent. Therefore, as shown in the formula (4), when the silver salt fine particles are dispersed in the alcohol solvent, the alcohol is surrounded on the surface of the silver salt fine particles. When the silver salt fine particles are refined to ultrafine particles, stable silver salt fine particle colloids are formed. In Equation (4), silver carbonate _(Ag 2 CO ₃₎ is shown as a silver salt.

FIG. 3 is a second process diagram of a formation reaction of composite silver nanoparticles according to the present invention. In order to clarify the reaction formula, silver carbonate is used as a silver salt. Silver carbonate on the surface of the silver carbonate fine particles reacts with alcohol, and aldehyde R _n-1 CHO is generated simultaneously with silveration as shown in formula (5). Moreover, as shown in Formula (6), there is also a reaction route in which silver alkoxide AgOR _n is immediately generated without forming an aldehyde. The aldehyde has a strong reducing action, and as shown in the formula (7), silver carbonate is reduced to form carboxylic acid R _n-1 COOH simultaneously with silveration. The intermediately produced Ag, AgOR _n , and R _n-1 COOH aggregate with each other by the reactions shown in Formula (8) and Formula (9), and form Ag _{k + m} (OR _n ) _m , Ag _{k + m} as composite silver nanoparticles. (OR _n ) _m R _n-1 COOH is produced. These composite silver nanoparticles are illustrated in equations (10) and (11). The reaction is a surface reaction of silver carbonate fine particles. The reaction continues while gradually penetrating from the surface into the interior, and the silver carbonate fine particles serving as the central nucleus are converted into silver nuclei. Finally, composite silver nanoparticles represented by formula (10) and formula (11) are produced, and in the present invention, this composite silver nanoparticle is written as CnAgAL.

  FIG. 4 is a high-resolution transmission electron microscope view of C2AgAL. The composite silver nanoparticles C2AgAL were produced in a monodispersed state at a production temperature PT of 65 ° C., and photographed with a high resolution transmission electron microscope. Lattice images consisting of parallel lines were observed in the silver nuclei, confirming that the silver nuclei were single crystals. The lattice spacing of the lattice image is 0.24 nm, which matches the (111) plane spacing of the bulk silver crystal, confirming that the silver nucleus is a silver single crystal.

  FIG. 5 is a high-resolution transmission electron microscope view of C4AgAL. The composite silver nanoparticle C4AgAL was produced in a monodispersed state at a production temperature PT of 80 ° C., and was photographed with a high resolution transmission electron microscope. Lattice images consisting of parallel lines were observed in the silver nuclei, confirming that the silver nuclei were single crystals. Similar to C2AgAL, the lattice spacing of the lattice image was 0.24 nm, which coincided with the (111) plane spacing of the bulk silver crystal, and it was confirmed that the silver nucleus was a silver single crystal.

  FIG. 6 is a thermal analysis diagram of C2AgAL in the atmosphere generated at a generation temperature PT = 65 ° C. The DTA curve is a differential thermal analysis curve with a DTA peak temperature T2 = 111 ° C. and a metallization temperature (silvering temperature) T3 = 115 ° C. The organic coating layer is strongly decomposed and diffused at the DTA peak temperature T2, and the temperature at which the diffusion is completed corresponds to the metallization temperature T3. The decomposition start temperature is given by a thermogravimetric measurement curve (TG curve) not shown, and the TG decrease start temperature T1 = 109 ° C. As described above, T1 <T2 <T3 is generally established, and it has become clear from the numerous experiments conducted by the present inventors that there is a relationship of T2-60 ≦ T1 ≦ T2. In other words, it was found that the TG decrease start temperature T1 is within 60 ° C. below the DTA peak temperature T2, and at the same time, is not more than the DTA peak temperature T2.

  FIG. 7 is a thermal analysis diagram of C4AgAL in the atmosphere generated at a generation temperature PT = 80 ° C. The DTA curve is a differential thermal analysis curve, and the TG curve is a thermogravimetric curve. TG decrease start temperature T1 = 103 ° C., DTA peak temperature T2 = 120 ° C., metallization temperature (silvering temperature) T3 = 122 ° C. It is also clear that the relationship of T2-60 ≦ T1 ≦ T2 is established.

  The present invention relates to 10 kinds of composite silver nanoparticles CnAgAL (n = 1 to 9, 11), and their production temperature PT, TG decrease start temperature T1, DTA peak temperature T2, metalization temperature T3 and alcohol boiling point BT are It is shown in Table 3.

  It was found that the generation temperatures PT of the 10 types of composite silver nanoparticles CnAgAL (n = 1 to 9, 11) were all 100 ° C. or lower, and as a result, the DTA peak temperature T2 was also suppressed to 150 ° C. or lower. Moreover, although the metallization temperature T3 is slightly higher than the DTA peak temperature T2, it was shown that the metallization temperature T3 is also 150 ° C. or less. CnAgAL is produced by keeping an alcohol solution at a constant production temperature PT, and since the boiling point of the alcohol is constant in the atmosphere, the production temperature PT can be easily kept at the boiling point BT by reacting the alcohol in a boiling state. . Since the alcohol boiling point of C1 to C3 is 100 ° C. or lower, it means that three types of CnAgAL of 1 ≦ n ≦ 3 can be generated by alcohol boiling reaction. Of course, other temperature control methods can be used.

  Table 4 shows the range of the TG decrease start temperature T1 of the composite silver nanoparticles CnAgAL. Table 4 shows the temperatures of T2-60, T1, and T2 with respect to C1 to C9 and C11. As a result, it was found that T2-60 ≦ T1 ≦ T2 holds for 10 types of composite silver nanoparticles.

  FIG. 8 is a production process diagram of a composite silver nanopaste. A predetermined weight percent of composite silver nanoparticle CnAgAL powder, a predetermined weight percent of silver fine particle Ag powder, and a predetermined weight percent of resin are prepared, and these three components are put into a mixing container. For example, the resin is fluidized by heating to 40 ° C. in a mixing container, and the paste is uniformly mixed. At this time, a rotation-revolution centrifuge that performs rotation at 700 rpm and revolution at 2000 rpm was used. If the heating temperature is about 40 ° C., the temperature is naturally raised by frictional heat, and therefore a forced heating operation is unnecessary. However, when it is 40 ° C. or higher, it can be efficiently fluidized by heating with a heater. Thereafter, the composite silver nanopaste is rapidly cooled, solidified and recovered. By solidification, the uniformly dispersed composite silver nanoparticles and silver fine particles are fixed by the resin and do not aggregate during storage.

A method in which the manufacturing process of FIG. 8 is modified is also adopted. First, a paste intermediate is produced by mixing a predetermined weight% of composite silver nanoparticles CnAgAL powder and a predetermined weight% of resin while heating. A predetermined weight percent of silver fine particle Ag powder is uniformly mixed with this paste intermediate while heating to produce a composite silver nanopaste, which is rapidly cooled to solidify. When frictional heat is used, forced heating is not necessary. In this manufacturing method, the composite silver nanoparticles are uniformly dispersed in the resin, and then the silver fine particles are uniformly dispersed. Therefore, the composite silver nanoparticles and the silver fine particles are dispersed independently, and uniform to eliminate the interaction between the two. It is characterized by further increasing dispersibility.
As another modification, first, a paste intermediate is produced by mixing a predetermined weight% of silver fine particle Ag powder and a predetermined weight% of resin while heating. A predetermined weight percent of composite silver nanoparticle CnAgAL powder is uniformly mixed with this paste intermediate while heating to produce a composite silver nanopaste, which is rapidly cooled to solidify. When frictional heat is used, forced heating is not necessary. In this modified manufacturing method, the silver fine particles are first uniformly dispersed in the resin, and then the composite silver nanoparticles are uniformly dispersed. Therefore, the composite silver nanoparticles and the silver fine particles are independently dispersed to eliminate the interaction between the two. Uniform dispersibility is further increased.
Of course, when silver fine particles are not added, it is needless to say that only uniform mixing of CnAgAL and resin is sufficient.

  Table 5 is an exemplary table of resins used in the present invention. Isobornylcyclohexanol (IBCH) is a so-called rosin-like, has no fluidity at room temperature, and has a property of fluidizing rapidly by heating. Glycerin has a lower viscosity than ICBH and is in the form of a so-called syrup, but has a melting point of 17 ° C., and thus solidifies at 10 ° C. in an environment without moisture. Therefore, glycerin almost loses its fluidity when cooled to the refrigerator temperature or lower, and fluidizes when heated, so that it can be used as the resin of the present invention in the same manner as IBCH. Both ICBH and glycerin are decomposed and diffused by firing in the air, and no carbides remain. In addition, a substance that is solid at room temperature of 10 ° C. or less, has a property of being liquefied when it is 40 ° C. or more, and completely disperses when baked can be used as the resin of the present invention. For example, higher alcohols having 14 or more carbon atoms can be used, and myristyl alcohol, palmityl alcohol, stearyl alcohol, behenyl alcohol and the like are listed. Their melting points are as shown in Table 3. Needless to say, resins similar to those described above can also be used as the resin of the present invention.

  Table 6 is a relationship table between the viscosity and temperature of IBCH. Since it is 150,000 centipoise (cP) at 30 ° C or lower, naturally it does not have fluidity even at 10 ° C, but when it reaches 40 ° C or higher, especially 50 ° C or higher, fluidity is rapidly developed and is optimal for the present invention. Resin.

  FIG. 9 is a characteristic diagram of viscosity and temperature of IBCH. The relationship between the viscosity and the temperature shown in Table 6 is plotted, and it can be seen that IBCH has a property of changing with temperature so rapidly that the viscosity is displayed on the logarithmic axis. All resins having such properties and having the property of being completely diffused by firing can be used in the present invention.

  FIG. 10 is a thermal analysis diagram of IBCH with a temperature increase rate of 3 ° C./min. From DTA, the complete evaporation temperature is 205 ° C., and from TG, the weight is found to be 0% at 205 ° C., and it is proved that the entire amount has evaporated and disappeared.

  Table 7 shows the relationship between the temperature increase rate of IBCH and the evaporation temperature. A temperature increase rate of 3 (° C./min) means a program temperature increase in which the temperature is increased while increasing by 3 ° C. per minute. The evaporation temperature decreases as the temperature increase rate decreases, and the evaporation temperature increases as the temperature increase rate increases. This property can be said to be a property of TG / DTA measurement. When the composite silver nanopaste of the present invention is baked, when the resin is first diffused, the rate of temperature increase is set small, and the alkoxide group is diffused after the resin is completely evaporated. On the other hand, when the alkoxide group is first diffused, the temperature increase rate should be set large, and then the resin will be completely evaporated. Usually, after the resin is completely evaporated, a method in which alkoxide groups are diffused is employed.

  FIG. 11 is a graph showing the relationship between the evaporation temperature of IBCH and the temperature rise rate. The relationship between the evaporation temperature shown in Table 7 and the temperature rising rate is plotted. Based on this graph, the evaporation rate can be arbitrarily adjusted by adjusting the temperature increase rate.

  Table 8 is a relationship table between viscosity and temperature of glycerin. At 0 ° C., it is 12100 centipoise (cP). Upon further cooling, the viscosity increases rapidly and becomes non-flowing. On the other hand, when the temperature is set to 10 ° C. or higher, the viscosity becomes 3900 (cP) or lower and exhibits fluidity. At this level of viscosity, the non-flowability may be considered to be small, but these viscosities are open to the atmosphere and absorb moisture. In particular, the melting point of glycerin is 17 ° C., and in an environment without moisture, it becomes solid when it becomes 17 ° C. or lower. Therefore, it can be said that it has non-fluidity at 10 ° C. or lower. While IBCH exhibits a slightly high temperature resin characteristic, glycerin is a resin that exhibits a low temperature resin characteristic, and by appropriately using both, non-fluidity / fluidity change can be realized. As described above, non-fluidity means non-aggregation of composite silver nanoparticles.

  FIG. 12 is a characteristic diagram of viscosity and temperature of glycerin. The relationship between the viscosity and the temperature shown in Table 8 is plotted, and it can be seen that the glycerin resin also has a property of rapidly changing with respect to temperature as the viscosity is displayed on the logarithmic axis. All resins having such properties and having the property of being completely diffused by firing can be used in the present invention.

  Table 9 is a list of alcohols used as solvents. The composite silver nanoparticles used in the present invention are CnAgAL (n = 1 to 9, 11) alkoxide type composite silver nanoparticles, the organic coating layer surrounding the silver core is an alkoxide group, and alcohol is used as a solvent. In addition, the composite silver nanoparticles have the property of dissolving very well in alcohol. As the alcohol, methanol, ethanol, butanol, hexanol, and octanol can be used. In addition to alcohol, organic solvents such as acetone, ether, benzene, ethyl acetate, terpineol, dihydroterpineol, butyl carbitol, cellosolve and the like can be used.

  As described above, the addition of a solvent reduces the silver content and causes agglomeration of composite silver nanoparticles and silver fine particles when it is made into a fluid paste, so a non-fluid paste without a solvent during storage and storage. It is recommended to add a solvent just before coating. Even when the storage period is very short, there is a possibility of aggregation, and therefore the addition of a solvent immediately before coating is desired. Even when a solvent is added, the amount added is preferably 10 mass% or less of the total amount, may be 5 mass% or less, and particularly preferably 1 to 2 mass%.

[Examples 11 to 113: Three types of composite silver nanopastes of C1 to C9 and C11]
Next, a composite silver nanopaste was prepared using the composite silver nanoparticles. The following three types of pastes were prepared from C1 to C9 and C11 CnAgAL, respectively. (1) CnAgAL + resin, (2) CnAgAL + solvent + resin, (3) CnAgAL + silver particles + solvent + viscosity imparting agent. One of the three types of CnAgAL was CnAgAL having a metallization temperature T3 shown in Table 3, and the other two were CnAgALs having another slightly different metallization temperature T3. CnAgAL having a metallization temperature T3 above 150 ° C. is also used. Two types of silver particles having a particle size of 0.4 μm and 1.0 μm were used. The solvent was selected from methanol, ethanol, butanol, xylene, and toluene. The resin was selected from IBCH, glycerin, myristyl alcohol (C ₁₄ H ₂₉ OH), palmityl alcohol (C ₁₆ H ₃₃ OH), stearyl alcohol (C ₁₈ H ₃₇ OH).

The particle size of the silver particles, the type of solvent, the type of resin, the mass% of each component, and the paste baking temperature in the atmosphere are as described in Tables 10 and 11. When preparing a paste with two components of CnAgAL and resin, the resin is first heated to 50 ° C. and fluidized, CnAgAL powder is mixed and kneaded therein, and cooled to 10 ° C. or less after kneading. Thus, a non-flowable paste was prepared. Immediately before application, this non-flowable paste is heated to 50 ° C. to be fluidized and applied to the test surface. In the case of adding a solvent, the resin and the solvent were mixed to fluidize the resin, and CnAgAL powder and silver particles were added and kneaded therein. And this fluid paste was applied to the test surface.
Tables 10 and 11 show the metallization temperature T3 (° C.) and the actual air paste firing temperature T (° C.) of CnAgAL of C1 to C9 and C11.

  The atmospheric paste firing temperature T is set higher than the metallization temperature T3 of CnAgAL. This is because it is necessary not only to metallize CnAgAL but also to evaporate the solvent and evaporate or decompose the resin. In addition, if the CnAgAL paste is baked at a temperature higher than the metallization temperature T3, an excellent metal film can be formed and a silver film having high electrical conductivity can be formed. The excellence of the silver film increases as the firing temperature T in the atmosphere increases. Therefore, as shown in Tables 10 and 11, the atmospheric paste firing temperature T was set higher than the metallization temperature T3.

  When 30 types of pastes shown in Examples 11 to 113 were applied to a heat-resistant glass substrate and baked at the atmospheric paste baking temperature shown in Tables 10 and 11, an excellent silver film was formed on the glass substrate. It was. When the surface of the formed silver film was observed with an optical microscope and the specific resistance was measured, it was confirmed that the film was a practical silver film, and it was concluded that the composite silver nanopaste of the present invention was effective.

  Next, the pastes of Example 23, Example 43, and Example 63 were subjected to thermal analysis. FIG. 13 is a thermal analysis diagram of the C2AgAL paste of Example 23. In the TG curve, peaks up to 150 ° C. indicate that IBCH has evaporated. Further, the step up to 175 ° C. shows the decomposition and diffusion of the organic coating layer of C2AgAL. This fact is also understood from the fact that the TG step and the DTA peak coincide.

  14 is a thermal analysis diagram of the C4AgAL paste of Example 43. FIG. In the TG curve, peaks up to 150 ° C. indicate that IBCH has evaporated. Furthermore, the step up to 175 ° C. shows the decomposition and diffusion of the organic coating layer of C4AgAL. This fact is also understood from the fact that the TG step and the DTA peak coincide.

  FIG. 15 is a thermal analysis diagram of the C6AgAL paste of Example 63. In the TG curve, peaks up to 150 ° C. indicate that IBCH has evaporated. Furthermore, the step up to 195 ° C. shows the decomposition and diffusion of the organic coating layer of C6AgAL. This fact can be understood from the fact that the TG step and the DTA peak coincide.

[Example 114: Joining of semiconductor electrode and circuit board]
A bonding test was performed with the semiconductor chip as the upper body and the circuit board as the lower body. The electrode end of the semiconductor chip was inserted into the through hole of the circuit board, and the composite silver nanopaste of Example 11 to Example 113 was applied to the contact part between them to obtain 30 types of paste test bodies. Then, the said coating part was heated locally with the paste baking temperature T of Table 10 and Table 11, the said coating part was metalized, and joining was completed. After cooling, when the appearance of the joint was inspected with an optical microscope, there were no problems with 30 types of specimens. An electrical continuity test and an electrical resistance measurement were performed, and it was confirmed that it functions effectively as an alternative solder. From the 30 types of bonding tests, it was found that the composite silver nanopaste according to the present invention can be used industrially as an alternative solder.

[Example 115: Formation of silver pattern on heat-resistant glass substrate]
Using the heat-resistant glass substrate as a base, the composite silver nanopastes of Examples 11 to 113 were screen-printed on the base to obtain 30 types of test bodies on which a predetermined paste pattern was formed. Then, the said test body was heated with the atmospheric paste baking temperature T of Table 10 and Table 11 with the electric furnace, and the silver pattern was formed from the said paste pattern. After cooling, when the surface of the silver pattern was inspected with an optical microscope, there were no problems with 30 types of specimens. From the 30 types of pattern formation tests, it was found that the composite silver nanopaste according to the present invention can be used industrially as a silver pattern forming material.

  The present invention is not limited to the above-described embodiments and modifications, and includes various modifications and design changes within the technical scope without departing from the technical idea of the present invention. Needless to say.

  According to the present invention, a silver nucleus having an average particle diameter of 1 to 20 nm composed of an aggregate of silver atoms is composed of one or more alcohol molecule residues, alcohol molecule derivatives or alcohol molecules having 1 to 9 or 11 carbon atoms. A metallic component containing at least composite silver nanoparticles having an organic coating layer is mixed with a resin. The resin is in a non-flowing state at 10 ° C. or lower, and the metallic component is held in a dispersed state. A composite silver nanopaste that can be fluidized and applied is provided. A paste that prevents aggregation of composite silver nanoparticles by non-fluidity and develops coating performance by heat fluidity is provided. Therefore, the composite silver nanopaste of the present invention can be used for electronic materials such as alternative solder, printed wiring, and conductive materials, magnetic materials such as magnetic recording media, electromagnetic wave absorbers, and electromagnetic resonators, far-infrared materials, and composite film forming materials. It can be applied to pastes in various fields such as structural materials, ceramics / metal materials such as sintering aids / coating materials, and medical materials.

Claims (10)

Around a silver nucleus having an average particle diameter of 1 to 20 nm composed of an aggregate of silver atoms, an alcohol molecule residue having 1 to 9 or 11 carbon atoms, an alcohol molecule derivative (herein, an alcohol molecule derivative is a carboxylic acid, an aldehyde Or is limited to one or more types of C _n-1 H _2n-1 COO) or a metal component containing at least composite silver nanoparticles formed with an organic coating layer made of one or more types of alcohol molecules and mixed with a resin. The composite silver nanopaste is characterized in that the resin is in a non-flowing state at 10 ° C. or lower, holds the metal component in a dispersed state, and is fluidized by heating to be applied. The composite silver nanopaste according to claim 1, wherein the composite silver nanoparticles are 95 (mass%) or less, and the resin is 20 (mass%) or less. The composite silver nanopaste according to claim 1, wherein silver fine particles having an average particle diameter of 0.1 to 10 μm are added as the metal component. The composite silver nanopaste according to claim 3, wherein the composite silver nanoparticle is 5 to 85 (mass%), the silver fine particles are 80 to 10 (mass%), and the resin is 20 (mass%) or less. The composite silver nanopaste according to any one of claims 1 to 4, wherein a desired amount of a solvent is added so that the fluidized state can be applied even at 10 ° C or lower to enable coating. A resin that is in a non-flowing state at 10 ° C. and fluidized by heating, an alcohol molecule residue having 1 to 9 or 11 carbon atoms around the silver nucleus having an average particle diameter of 1 to 20 nm composed of an aggregate of silver atoms, an alcohol molecule A composite silver nanoparticle formed with an organic coating layer made of a derivative (here, the alcohol molecule derivative is limited to one or more of carboxylic acid, aldehyde or C _n-1 H _2n-1 COO) or one or more of alcohol molecules The particles are mixed as a metal component, the resin is fluidized under heating to knead the whole, and after the kneading, the resin is cooled to a temperature at which the resin does not flow, and the metal component is dispersed in the resin. A method for producing a composite silver nanopaste characterized by holding. The method for producing a composite silver nanopaste according to claim 6, wherein the average particle diameter of the silver nuclei is 1 to 20 nm, and the average particle diameter of the silver fine particles is 0.1 to 10 µm. The method for producing a composite silver nanopaste according to claim 6 or 7, wherein a desired amount of a solvent is added to make a paste that can be applied in a fluidized state even at 10 ° C or lower. A composite silver nanopaste according to any one of claims 1 to 5 is prepared, the composite silver nanopaste is applied to a lower body to form a paste layer, the upper body is disposed on the paste layer, and heated. A joining method, wherein the paste layer is silvered to join the lower body and the upper body. A composite silver nanopaste according to any one of claims 1 to 5 is prepared, the composite silver nanopaste is coated on a surface of a substrate in a predetermined pattern to form a paste pattern, and the paste pattern is silvered by heating. Forming a silver pattern by patterning.