JP2020087766A - Composition for joint - Google Patents

Abstract

To provide a composition for joint forming a conjugate excellent in joint strength.SOLUTION: There is provided a composition for joint containing a metal powder, a coated metal particle (A) with one or more kinds of molecule selected from a plurality of aliphatic carboxylic acid (A1) and aliphatic aldehyde (A2) coated on a surface of a metal nuclear particle smaller in particle diameter than the metal powder at density of 2.5 to 5.2 molecules/nm, and one or more kinds of solvent (B) selected from aliphatic carboxylic acid-based solvent having boiling point of 160°C to 300°C, and a solvent (B) selected from aliphatic aldehyde-based solvent (B2) having the boiling point of 160°C to 300°C.SELECTED DRAWING: None

Description

The present invention relates to a bonding composition.

Printable electronics, which do not require patterning by exposure by directly printing a dispersion containing metal particles on a wiring pattern by various printing methods such as inkjet, are drawing attention.
It is known that metal particles of several tens of nm or less exhibit various physical and chemical characteristics different from those of bulk metal as the particle diameter becomes smaller. For example, it is known that the melting point of metal particles becomes lower than the melting point of bulk metal when the particle size becomes smaller. Therefore, from the viewpoint of lowering the temperature during sintering, it has been considered to use metal particles having a small particle size. Examples of the printing method include an inkjet printing method, a screen printing method, a flexo printing method, and a dispense printing method.

The present inventors include, in Patent Document 1, copper core particles, and a plurality of aliphatic carboxylic acid molecules arranged on the surface of the copper core particles at a density of 2.5 to 5.2 molecules per 1 nm ^2. , Coated copper particles are disclosed. In addition, in the patent document 2, the present inventors disclose a silver nucleus particle, and a plurality of aliphatic carboxylic acid molecules arranged on the surface of the silver nucleus particle at a density of 2.5 to 5.2 molecules per nm ² . And coated silver particles are disclosed.
These coated copper particles and coated silver particles are said to have excellent oxidation resistance and sinterability.

JP, 2016-069716, A JP, 2017-179403, A

Generally, the bonding composition containing the coated metal particles is heated to sinter the coated metal particles to form a bonded body. However, the metal particles may be oxidized due to desorption of coating molecules during the sintering process. In such a case, the bonding strength of the bonded body may decrease.

The present invention has been made in view of such circumstances, and an object thereof is to provide a bonding composition that forms a bonded body having excellent bonding strength.

One embodiment of the bonding composition according to the present invention comprises a metal powder and a plurality of aliphatic carboxylic acids (A1) and aliphatic aldehydes (A2) on the surface of metal core particles having a smaller particle size than the metal powder. Coated metal particles (A) coated with one or more selected coating molecules at a density of 2.5 to 5.2 molecules/nm ² and an aliphatic carboxylic acid solvent having a boiling point of 160° C. or higher and 300° C. or lower ( B1) and at least one solvent (B) selected from aliphatic aldehyde solvents (B2) having a boiling point of 160° C. or higher and 300° C. or lower.

In one embodiment of the bonding composition according to the present invention, the aliphatic aldehyde solvent (B2) contains decanal.

In one embodiment of the bonding composition according to the present invention, the aliphatic carboxylic acid solvent (B1) contains octanoic acid.

According to the present invention, it is possible to provide a bonding composition that forms a bonded body having excellent bonding strength.

[Composition for bonding]
The bonding composition of the present embodiment is selected from a metal powder and a plurality of aliphatic carboxylic acids (A1) and aliphatic aldehydes (A2) on the surface of metal core particles having a smaller particle size than the metal powder. Coated metal particles (A) coated with at least one kind of coating molecule at a density of 2.5 to 5.2 molecules/nm ² , an aliphatic carboxylic acid solvent (B1) having a boiling point of 160° C. or more and 300° C. or less, and a boiling point At least 160° C. and not more than 300° C. and at least one solvent (B) selected from aliphatic aldehyde solvents (B2).

That is, the bonding composition of the present embodiment includes metal powder, coated metal particles (A) coated with a coating molecule having an aliphatic group, a solvent (B) having a boiling point of 160° C. or higher and 300° C. or lower, Contains. In such a structure, since the boiling point of the solvent (B) is 160° C. or higher and 300° C. or lower, it is hard to volatilize, protects the coated metal particles (A) and the metal powder even in the sintering process, and has oxidation resistance. It is estimated to improve.
From the above, the bonding composition of the present embodiment can form a bonded body having excellent bonding strength.

<Metal powder>
As the metal powder used in the present embodiment, a known metal powder used in a bonding composition can be used. The kind of metal in the metal powder is not particularly limited, and one or more kinds can be appropriately selected and used from the metals that can be used for the metal core particles described later. Above all, it is preferable to use copper or silver from the viewpoint of conductivity. The mass ratio of the metal powder and the coated metal particles (A) is not particularly limited, but from the viewpoint of increasing the bonding strength, 20:80 to 80:20 is preferable, 30:70 to 70:30 is more preferable, and 40: Even more preferably 60 to 60:40.

The particle size of the metal powder used in this embodiment is not particularly limited, but the average primary particle size of the metal powder is preferably 0.3 or more and 10 μm or less, more preferably 0.4 or more and 5 μm or less, and even more preferably 0. It can be 0.5 or more and 1.0 μm or less. By using the metal powder having an average primary particle diameter of 10 μm or less, the density of the metal powder in the bonding composition can be made more uniform and the bonding strength can be improved. Further, in the present embodiment, plural kinds of metal powders having different average primary particle sizes may be mixed and used. When a mixture of multiple types of metal powders with different average primary particle sizes is used, the metal powder with relatively small average primary particle size enters between the metal powders with relatively large average primary particle size, and the packing density as a whole Can be improved.

<Coated metal particles>
The coated metal particles (A) used in this embodiment are selected from a plurality of aliphatic carboxylic acids (A1) and aliphatic aldehydes (A2) on the surface of the metal core particles having a smaller particle size than the above-mentioned metal powder. Particles coated with one or more types of coating molecules at a density of 2.5 to 5.2 molecules/nm ² . The carboxy group side of the coating molecule is adsorbed on the surface of the metal core particle to form a monomolecular film. Therefore, it is presumed that the surface of the metal core particle is protected by the coating molecule to suppress the oxidation and has high oxidation resistance. For example, in the coated silver particles using silver core particles as the metal core particles, the content ratio of silver oxide and silver hydroxide after 2 months from production is 100% by mass of the silver core particles in the coated silver particles. It is also possible to suppress it to 5 mass% or less. The generation of the metal oxide in the coated metal particles (A) can be confirmed by the X-ray diffraction (XRD) measurement of the coated metal particles (A).

Further, since the coating molecule is bonded to the metal core particle by physical adsorption or the like, it is considered that the coating molecule diffuses and desorbs at a relatively low temperature. Therefore, the surface of each metal core particle is easily exposed by heating, and the surfaces of the metal core particles can be brought into contact with each other, so that the coated metal particles (A) have excellent sinterability at low temperatures.

(Metal core particles)
The average primary particle diameter of the metal core particles used in the present embodiment is not particularly limited as long as it is smaller than the average primary particle diameter of the metal powder, but from the viewpoint of low temperature sinterability and dispersibility, it is less than 300 nm. The thickness is preferably 250 nm or less, more preferably 200 nm or less. The average primary particle diameter of the metal core particles is usually 1 nm or more, preferably 5 nm or more, and more preferably 20 nm or more. The average primary particle diameter of the metal core particles is an arithmetic average value of the primary particle diameters of any 20 metal core particles observed by a scanning electron microscope (SEM).

The material of the metal core particles may be any metal that exhibits sufficient bonding strength after sintering, for example, gold, silver, copper, platinum, aluminum, iron, chromium, tin, nickel, zinc, lead, indium, bismuth, Examples thereof include germanium, antimony, cobalt, palladium, rhodium, molybdenum, tungsten, titanium, zirconium, gallium, arsenic, boron, silicon, and alloys thereof. Further, the material of the metal core particles is preferably a metal exhibiting conductivity after sintering, of which gold, silver, or copper is more preferable, and silver or copper is still more preferable. By using these metals, the bonding composition of this embodiment can be applied to, for example, printing of electronic circuits. Moreover, since the coated metal particles (A) used in the present embodiment have excellent oxidation resistance, copper can be preferably used as the metal core particles. When there are a plurality of coated metal particles (A), the contained metal core particles may be the same or different from each other.

The metal core particles may contain metal oxides, metal hydroxides, and other impurities as long as the effects of the present invention are not impaired. From the viewpoint of conductivity, the content ratio of the metal oxide and the metal hydroxide is preferably 5% by mass or less, more preferably 3% by mass or less, and 1% by mass or less with respect to the metal core particles. Is even more preferable. From the viewpoint of conductivity, the content ratio of the metal in the metal core particles is preferably 95% by mass or more, more preferably 97% by mass or more, and even more preferably 99% by mass or more. preferable.

The shape of the metal core particles can be appropriately selected depending on the application and the like. Examples of the shape include a substantially spherical shape including a true spherical shape, a plate shape, and a rod shape. Among them, the substantially spherical shape is preferable. According to the method for producing coated metal particles (A) described below, substantially spherical metal core particles that can approximate a spherical shape can be obtained. The particle size of the coated metal particles (A) can be determined by SEM observation.

(Coating molecule)
As the coating molecule in the present embodiment, one or more kinds of molecules selected from an aliphatic carboxylic acid (A1) or an aliphatic aldehyde (A2) are used alone or in combination. The coating molecule coats the surface of the metal core particle with a density of 2.5 to 5.2 molecules per 1 nm ² , and has the dispersibility of the metal core particle and the effect of suppressing oxidation. Further, during sintering, the coating molecules are easily removed from the surface of the metal core particles, or decomposed or volatilized, so that the residue in the bonded body is suppressed. Thereby, a conductor having excellent electric conductivity can be obtained.

The boiling point of the coating molecule in the present embodiment is preferably 150°C or higher, more preferably 160°C or higher, and even more preferably 200°C or higher. When the boiling point of the coating molecule satisfies the above conditions, the coating molecule sufficiently protects the metal core particles even in the sintering process, so that the oxidation resistance of the metal core particles can be improved and the bonding strength can be increased. .. On the other hand, from the viewpoint of increasing the bonding strength, the boiling point of the coating molecule is preferably 300°C or lower.

<<aliphatic carboxylic acid>>
The aliphatic carboxylic acid (A1) is a compound having a structure in which one or two or more carboxy groups are substituted in the aliphatic compound, and in the present embodiment, the aliphatic carboxylic acid is usually provided on the surface of the metal core particle. The carboxy group of the acid (A1) is located. In the present embodiment, a structure in which one carboxy group is substituted in the aliphatic compound, that is, a compound having an aliphatic hydrocarbon group and one carboxy group is preferable.

The aliphatic hydrocarbon group that constitutes the aliphatic carboxylic acid (A1) is a hydrocarbon group having a linear, branched, or cyclic structure, and may have an unsaturated bond. In the present embodiment, it is preferable to use a linear aliphatic hydrocarbon group having no branched or cyclic structure from the viewpoint of easily forming a monomolecular film on the surface of the metal core particles with a predetermined density. The unsaturated bond may be a double bond or a triple bond, but is preferably a double bond. When the aliphatic hydrocarbon group has an unsaturated bond, the number thereof is preferably 1 to 3 in one molecule, more preferably 1 to 2, and even more preferably 1. preferable.

Among these, the aliphatic carboxylic acid (A1) in the present embodiment preferably has a carboxy group at the end of the straight-chain aliphatic hydrocarbon group. When the aliphatic hydrocarbon group has a linear structure, the affinity between the coated metal particles (A) and the solvent (B) described below can be increased and the dispersibility of the coated metal particles (A) can be improved. In the aliphatic carboxylic acid (A1), the aliphatic group preferably has 3 or more carbon atoms, more preferably 5 or more carbon atoms, and even more preferably 7 or more carbon atoms. When the number of carbon atoms is 3 or more, the dispersibility and oxidation resistance of the coated metal particles (A) can be improved. On the other hand, the aliphatic group preferably has 17 or less carbon atoms, more preferably 16 or less carbon atoms, and even more preferably 11 or less carbon atoms. When the number of carbon atoms is 17 or less, the coated metal particles (A) are easily removed during sintering, and a conductor having excellent electric conductivity can be obtained. In addition, in this embodiment, the number of carbon atoms of the aliphatic group does not include the carbon atoms constituting the carboxy group.

Specific examples of preferable aliphatic carboxylic acid (A1) include butyric acid, caproic acid, caprylic acid, pelargonic acid, stearic acid, palmitoleic acid, oleic acid, vaccenic acid, linoleic acid, and linolenic acid. The aliphatic carboxylic acids (A1) can be used alone or in combination of two or more.

<<aliphatic aldehyde>>
In the present embodiment, an aliphatic aldehyde (A2) can be arranged on the surface of the metal core particles instead of the aliphatic carboxylic acid (A1) or in combination with the aliphatic carboxylic acid (A1). .. Even in this case, as with the aliphatic carboxylic acid (A1), coated metal particles (A) capable of forming a conductor having excellent electric conductivity can be obtained.

The aliphatic aldehyde (A2) is a compound having a structure in which one or more aldehyde groups are substituted in the aliphatic compound. The aliphatic aldehyde (A2) used in the present embodiment is preferably a structure having one aldehyde group substituted in the aliphatic compound, that is, a compound having an aliphatic hydrocarbon group and one aldehyde group. In the present embodiment, the aldehyde group of the aliphatic aldehyde (A2) is usually arranged on the surface of the metal core particle. By arranging the aldehyde group on the surface of the metal core particle, the reduction effect of the aliphatic aldehyde (A2) suppresses the oxidation of the surface of the metal core particle and the effect of cleaning contaminants can be obtained. Moreover, it is presumed that the aldehyde group is arranged on the surface of the metal core particles to have an effect of removing foreign matters and oxides on the surface of the base material.

As the aliphatic hydrocarbon group constituting the aliphatic aldehyde (A2), the same one as the aliphatic carboxylic acid (A1) can be selected.
Specific examples of preferable aliphatic aldehyde (A2) include butyraldehyde, hexyl aldehyde, octyl aldehyde, nonyl aldehyde, octadecyl aldehyde, and hexadecenyl aldehyde. The aliphatic aldehyde (A2) can be used alone or in combination of two or more.

The surface of the metal core particles is coated with one or more kinds of coating molecules selected from a plurality of aliphatic carboxylic acids (A1) and aliphatic aldehydes (A2) at a density of 2.5 to 5.2 molecules/nm ^2. ing. That is, the surface of the metal core particle is coated with a coating layer containing coating molecules, and the coating density is 2.5 to 5.2 molecules/nm ² . From the viewpoint of dispersibility and oxidation resistance, it is preferred that the coating density is from 3.0 to 5.2 molecular / nm ^2, and more preferably from 3.5 to 5.2 molecular / nm ^2.

The coating density of the coating molecules on the surface of the metal core particles can be calculated as follows. With respect to the coated metal particles (A), the organic component adhering to the surface is extracted by liquid chromatography (LC) according to the method described in JP 2012-88242 A, and the component analysis is performed. In addition, TG-DTA measurement (thermogravimetric measurement/differential thermal analysis) is performed to measure the amount of organic components contained in the coated metal particles (A). Next, the amount of the coating molecule contained in the coated metal particles (A) is calculated together with the LC analysis result. Further, the average primary particle diameter of the metal core particles is measured by SEM image observation.
From the above analysis results, the number of coating molecules contained in 1 g of the coated metal particles (A) is represented by the following formula (a).
[The number of molecules of the coating _{molecules] = M A / (M w} / N A) ··· (a)
Here, M _A is the mass (g) of the coating molecule contained in 1 g of the coated metal particles (A), M _w is the molecular weight of the coating molecule, and N _A is the Avogadro constant. When two or more types of coating molecules are contained, the number of molecules is calculated for each component and summed.
The shape of the metal core particle is approximated to a sphere, and the mass of the metal core particle M _B (g) is determined by subtracting the amount of the organic component from the mass of the coated metal particle (A). The number of metal core particles in 1 g of the coated metal particles (A) is represented by the following formula (b).
[Metal Number core _{particles] = M B / [(4πr} 3/3) × d × 10 -21] ··· (b)
Here, M _B is the mass (g) of the metal particles contained in 1 g of the coated metal particles (A), r is the radius (nm) of the primary particle diameter calculated by SEM image observation, and d is the metal density. (G/cm ³ ) (d=8.94 for copper). The surface area of the metal core particles contained in 1 g of the coated metal particles (A) is represented by the following expression (c) from the expression (b).
[Surface area of metal core particles (nm ² )]=[number of metal core particles]×4πr ² (c)
From the above, the coating density (molecules/nm ² ) of the metal particles by the coating molecule is calculated by the following equation (d) using the equations (a) and (c).
[Coating density]=[Number of molecules of coating molecule]/[Surface area of metal core particles] (d)

The binding state between the coating molecule and the metal core particle in the coated metal particle (A) may be ionic bond or physical adsorption. From the viewpoint of the sinterability of the coated metal particles (A), the coating molecule is preferably physically adsorbed on the surface of the metal core particle, and is physically adsorbed on the surface of the metal core particle with a carboxy group or an aldehyde group. Is preferred.

The physical adsorption of the coating molecules to the metal core particles can be confirmed by analyzing the surface composition of the coated metal particles (A). Specifically, the time-of-flight secondary ion mass spectrometry (ToF-SIMS) surface analysis is performed on the coated metal particles (A), and only substantially free coating molecules are detected and bound to metal atoms. This can be confirmed by the fact that the coating molecule is not substantially detected. Here, when the coating molecule bound to the metal atom is not substantially detected, the signal amount of the coating molecule attached to the metal core particle is 5% or less with respect to the signal amount of the free coating molecule. It means that it is present and is preferably 1% or less.

In addition, the fact that the coating molecule is physically adsorbed on the surface of the metal particle with a carboxy group or an aldehyde group means that the infrared absorption spectrum of the coated metal particle (A) is measured, and it is substantially C-O-metal. It can be confirmed that only the stretching vibration peak derived from the salt is observed, and the stretching vibration peak derived from the free carboxylic acid or the like is not substantially observed.

The particle size of the coated metal particles (A) can be appropriately selected depending on the application and the like. The average primary particle diameter of the coated metal particles (A) is preferably 0.02 μm or more and 5 μm or less, more preferably 0.05 μm or more and 5 μm or less from the viewpoint of dispersibility, conductivity, and crack suppression. , 0.07 μm or more and 2.5 μm or less is even more preferable.
The average primary particle diameter of the coated metal particles (A) is calculated as an arithmetic mean value D _SEM of the primary particle diameters of arbitrary 20 coated metal particles (A) by SEM observation.
The value of the variation coefficient (standard deviation SD/average primary particle diameter D _SEM ) of the particle size distribution of the coated metal particles (A) is, for example, 0.01 to 0.5, preferably 0.05 to 0.3. .. In particular, since it is manufactured by the method for manufacturing the coated metal particles (A) described below, the coefficient of variation of the particle size distribution is small, and the particle size can be made uniform. Since the coefficient of variation of the particle size distribution of the coated metal particles (A) is small, it is possible to obtain a highly concentrated dispersion having excellent dispersibility.

The coated metal particles (A) used in the present embodiment are excellent in oxidation resistance and sinterability, and the resulting bonded body exhibits high bonding strength and electrical conductivity. Therefore, it can be suitably used for a bonding composition that is printed on a base material to form a wiring pattern or the like.

The proportion of the coated metal particles (A) contained in the bonding composition of the present embodiment is not particularly limited, but can be appropriately changed depending on the application. For example, in the case of screen printing, the ratio of the coated metal particles (A) to the total amount of the bonding composition can be 5 to 95% by mass, and in the case of inkjet printing, the coated metal particles (A) to the total amount. ) Can be 40 to 90% by mass.

<Method for producing coated metal particles>
The coated metal particles (A) used in the present embodiment are selected from a metal carboxylate containing a metal to be the specific metal core particles, the specific aliphatic carboxylic acid (A1) and the aliphatic aldehyde (A2). Is produced using one or more molecules of For example, it can be manufactured with reference to the descriptions in paragraphs 0031 to 0066 and paragraph 0085 of Patent Document 1 described above. Alternatively, it can be produced with reference to the descriptions of paragraphs 0052 to 0101 and paragraphs 0110 to 0114 of Patent Document 2 described above.
In a preferred method for producing coated metal particles (A), a reaction solution containing a metal carboxylate, a coating molecule, and a medium is prepared, and a complex compound produced in the reaction solution is pyrolyzed to give a metal nucleus. It is possible to obtain coated metal particles (A) in which the surface of the particles is coated with the coating molecules at a density of 2.5 to 5.2 molecules per nm ² .

The carboxylic acid in the metal carboxylate can be appropriately selected from the viewpoint of the type of metal and the ease of manufacturing the metal carboxylate. Examples of the carboxylic acid used include formic acid, oxalic acid, citric acid and the like. Carbonic acid may be used instead of carboxylic acid depending on the type of metal. When copper is used as the metal, it is preferable to use copper formate as the metal carboxylate. When silver is used as the metal, silver formate, silver oxalate, silver carbonate, silver citrate, and the like can be used as the metal carboxylate. Among them, silver oxalate is used because of its high thermal decomposition temperature. It is preferable to use. The metal constituting the metal carboxylate can be the same as that of the metal core particles.

It is preferable that the reaction liquid contains an amino alcohol capable of forming a complex with a metal carboxylate. By forming a complex between the metal carboxylate and the amino alcohol, the solubility in the medium described later is improved.
The amino alcohol may be an alcohol compound having at least one amino group. The amino alcohol is preferably a monoamino monoalcohol compound, and more preferably an amino group-unsubstituted monoamino monoalcohol compound. It is also preferable that the amino alcohol is a monodentate monoamino monoalcohol compound. Specific examples of preferable amino alcohols include 2-aminoethanol, 3-amino-1-propanol, 5-amino-1-pentanol, DL-1-amino-2-propanol and N-methyldiethanolamine.

The medium constituting the reaction solution can be appropriately selected and used from those which do not inhibit the metal reduction of the metal carboxylate. The medium is usually an organic solvent. The medium has at least a main medium having low compatibility with amino alcohol, and may optionally have an auxiliary medium compatible with amino alcohol.

Examples of preferred main media include ethylcyclohexane, C9-based cyclohexane [manufactured by Maruzen Sekiyu, trade name: Swaclean #150], n-octane and the like. The medium may be used alone or in combination of two or more.
Examples of preferable auxiliary media include glycol ethers such as EO (ethylene oxide) type glycol ether, PO (propylene oxide) type glycol ether, and dialkyl glycol ether.
Each of the main medium and the auxiliary medium can be independently used alone or in combination of two or more.

The complex compound formed in the reaction solution preferably contains a metal ion and carboxylic acid and amino alcohol as ligands. The inclusion of amino alcohol as a ligand lowers the thermal decomposition temperature of the complex compound.
The complex compound produced in the reaction solution produces a metal reduced by the thermal decomposition treatment. The temperature of the thermal decomposition treatment may be appropriately adjusted in consideration of the thermal decomposition temperature of the complex compound coordinated with the amino alcohol as described above. By setting the temperature of the thermal decomposition treatment to be low, the formation of acid amide due to the dehydration reaction between the coating molecule and the amino alcohol is suppressed, and the washability of the obtained coated metal particles (A) tends to be improved.

A metal reduced by the thermal decomposition treatment of the complex compound grows and grows, and the coating molecules present in the reaction liquid adsorb to the surface of the obtained metal core particles, so that the surface is coated with the coating molecule. Metal particles (A) are obtained. The adsorption of the coating molecule on the surface of the metal core particle is preferably physical adsorption. This improves the sinterability of the coated metal particles (A). By suppressing the generation of metal oxides in the thermal decomposition treatment of the complex compound, physical adsorption of the coating molecules is promoted.

In the method for producing coated metal particles (A), factors controlling the particle size distribution of the produced coated metal particles (A) include, for example, the type and amount of coating molecules, the concentration of metal carboxylate and the ratio of medium ( Main medium/auxiliary medium) etc. The factor controlling the size of the coated metal particles (A) is to appropriately maintain the heating rate that controls the number of metal nuclei generated, that is, the stirring rate related to the amount of heat input to the reaction system and the size of the microreaction field. Can be aligned.

<Solvent>
The solvent (B) used in the present embodiment is selected from an aliphatic carboxylic acid solvent (B1) having a boiling point of 160°C to 300°C and an aliphatic aldehyde solvent (B2) having a boiling point of 160°C to 300°C. Includes one or more of the following: The solvent (B) is a liquid under 25° C. and 1 atm.

The boiling point of the solvent (B) may be 160° C. or higher, but it is preferably 200° C. or higher from the viewpoint of remaining in the bonding composition and protecting the coated metal particles (A) during the sintering process. The boiling point of the solvent (B) may be 300° C. or lower, but it is preferably 280° C. or lower from the viewpoint of suppressing the residue after sintering and enhancing the bonding strength and conductivity of the bonded body. It is more preferable that the temperature is not higher than C.

The aliphatic group of the solvent (B) preferably has a linear, branched or cyclic structure. In the present embodiment, the aliphatic group of the solvent (B) is a straight-chain aliphatic hydrocarbon group having no branched or cyclic structure because it easily interacts with the coating molecule of the coated metal particles (A). Preferably there is. Further, the solvent (B) may have a double bond or a triple bond as an unsaturated bond, but since it easily interacts with the coating molecule of the coated metal particles (A), it has an unsaturated bond. Not preferred. When the aliphatic hydrocarbon group has an unsaturated bond, the unsaturated bond is preferably a double bond. Further, the number thereof is preferably 1 to 3 in one molecule, more preferably 1 to 2, and even more preferably 1.

The number of carbon atoms of the aliphatic group in the solvent (B) is not particularly limited, but is preferably 3 or more, preferably 5 or more, and more preferably 6 or more. When the number of carbon atoms of the aliphatic group of the solvent (B) satisfies the above conditions, the compatibility with the coating molecule of the coated metal particles (A) is excellent. Therefore, the protection of the coated metal particles (A) can be further enhanced. Further, as will be described later, when the number of carbon atoms of the aliphatic group of the solvent (B) satisfies the above conditions, a hydrocarbon solvent having high compatibility is included as another solvent, whereby the coated metal particles (A) The oxidation resistance can be further enhanced.

The solvent (B) includes at least one selected from the above-mentioned aliphatic carboxylic acid solvent (B1) and aliphatic aldehyde solvent (B2), but among them, it is selected from the aliphatic aldehyde solvent (B2). It is preferable to include one or more of Inclusion of a reducing aliphatic aldehyde solvent (B2) in the bonding composition suppresses oxidation of the coated metal particles due to oxygen and the like in the air, and further enhances chemical stability of the coated metal particles. You can

When the aliphatic aldehyde solvent (B2) is used as the solvent (B), it is preferably selected from, for example, octanal, decanal, dodecanal, tridecanal, and a mixture thereof, particularly, the acid resistance of the coated metal particles (A). From the viewpoint of improving the chemical conversion property, it is preferable to select from decanal, dodecanal and a mixture thereof, and it is more preferable to use decanal.

When the aliphatic carboxylic acid solvent (B1) is used as the solvent (B), it is preferably selected from, for example, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, and a mixture thereof, and particularly, a coating metal From the viewpoint of compatibility with the particles (A), octanoic acid, nonanoic acid, and mixtures thereof are preferably selected, and octanoic acid is more preferably used.

The proportion of the solvent (B) contained in the bonding composition of the present embodiment is not particularly limited, but can be, for example, 0.1% by mass or more and 95% by mass or less, and 0.2% by mass or more and 90% by mass. % Or less, and more preferably 0.4% by mass or more and 80% by mass or less.

<Other ingredients>
The bonding composition according to the present invention contains the above-mentioned metal powder, the coated metal particles (A), and the solvent (B), and may be added as needed within a range not impairing the effects of the present invention. And may further contain other components. Examples of the other components include other solvents different from the solvent (B), antioxidants, dispersants, thickeners, gelling agents, and the like. By combining a solvent, a dispersant, and a thickener, for example, the rheological properties of the bonding composition can be adjusted.

The viscosity of the mixture of the other solvent, the antioxidant, the dispersant, the thickener and the gelling agent may be appropriately adjusted according to the printing means. For example, the viscosity at 25° C. and 10 rpm can be appropriately adjusted within the range of 0.01 Pa·s or more and 500 Pa·s or less, and preferably 0.01 Pa·s or more and 50 Pa·s or less.

(Other solvents)
As the other solvent that can be contained in the bonding composition according to the present embodiment, a solvent having a high compatibility with the solvent (B) is used. Examples of the other solvent include hydrocarbon solvents, halogenated hydrocarbon solvents, alcohol solvents, ether solvents, ester solvents, ketone solvents, amide solvents, sulfonic acid solvents, and carbon numbers. Are less than 8 or more than 12 carbon atoms or aromatic carboxylic acid solvents or aldehyde solvents, and one or a mixture of two or more selected from these can be used. Among them, from the viewpoint of improving the dispersibility of the metal powder and the coated metal particles (A), it is preferable to use one kind or a mixture of two or more kinds selected from hydrocarbon solvents, and it is preferable to use liquid paraffin. ..
When the bonding composition according to the present embodiment contains another solvent, the ratio of the other solvent is not particularly limited, but may be, for example, 0.1% by mass or more and 95% by mass or less.

<<Liquid paraffin>>
When liquid paraffin is used in the bonding composition of the present embodiment, the liquid paraffin is a mixture of aliphatic hydrocarbons having a linear, branched, or cyclic structure, and is preferably liquid at room temperature.
Since the surface of the coated metal particles (A) is covered with a hydrophobic group, it has excellent compatibility with liquid paraffin. Therefore, the coated metal particles (A) can be dispersed in the liquid paraffin in a stable state for a long time. Further, since liquid paraffin is chemically stable, it is difficult to react with the coated metal particles (A) and the metal powder. Therefore, oxidation of the coated metal particles (A) and the metal powder in the bonding composition is suppressed.
Liquid paraffin also exhibits good dispersibility in the metal powder.

Liquid paraffin is a mixture of aliphatic hydrocarbons having different molecular weights, and has a wide range of vaporization temperatures. That is, when the liquid paraffin in the present embodiment is heated, it begins to volatilize gradually after exceeding a certain temperature, and by further raising the temperature, almost all can be volatilized. The temperature at which the liquid paraffin begins to volatilize is preferably higher than room temperature and lower than the sintering temperature of the coated metal particles (A). The temperature at which all liquid paraffin is volatilized is preferably higher than the sintering temperature of the coated metal particles (A) and the boiling point of the solvent (B). For example, liquid paraffin having a vaporizing temperature in the range of 50°C to 350°C can be used.
Under such conditions, when the bonding composition according to the present invention is heated, the liquid paraffin gradually vaporizes, so that the concentrations of the coated metal particles (A) and the metal powder gradually increase. Further, since the liquid paraffin remains even after the solvent (B) is volatilized, it is possible to further improve the oxidation resistance of the coated metal particles (A) and increase the bonding strength of the sintered body. Therefore, the coated metal particles (A) can be sintered in a high-density state, and a stronger joined body can be formed.

The density of the liquid paraffin is not particularly limited, but it is preferably 0.80 g/cm ³ or more at 15° C., more preferably 0.82 g/cm ³ or more, and 0.83 g/cm ³ or more. It is even more preferable. Liquid paraffin having the above density has a large molecular weight and tends to be hard to volatilize. Such liquid paraffin can remain without being dried even if it is left for a long time in a state of being coated on a substrate. Therefore, it is easy to handle in processes such as screen printing and can be suitably used as a material for conductive ink. The density of the liquid paraffin is preferably at 15 ℃ is 0.90 g / cm ³ or less, more preferably 0.88 g / cm ³ or less, further not less 0.87 g / cm ³ or less Is more preferable. Since the liquid paraffin having the above density tends to volatilize at a relatively low temperature, it tends to hardly remain in the bonded body. Therefore, the bonding composition using the liquid paraffin has a high bonding strength and can form a bonded body having high thermal conductivity and high electrical conductivity.

The kinematic viscosity of liquid paraffin is not particularly limited, but is preferably 4 mm ² /s or more at 37.8° C., more preferably 5 mm ² /s or more, and further preferably 10 mm ² /s or more. Is more preferable. In the liquid paraffin having the above-mentioned kinematic viscosity, the coated metal particles and the metal powder are hard to precipitate, so that the dispersibility tends to be good. The kinematic viscosity of the liquid paraffin at 37.8° C. is preferably 100 mm ² /s or less, more preferably 90 mm ² /s or less, and even more preferably 40 mm ² /s or less. The liquid paraffin having the above kinematic viscosity tends to volatilize at a relatively low temperature, and thus tends to hardly remain in the bonded body. Therefore, the bonding composition using the liquid paraffin has a high bonding strength and can form a bonded body having high thermal conductivity and high electrical conductivity.

Examples of liquid paraffin satisfying the above conditions include High Coal K (Kaneda Co., Ltd.) series liquid paraffin. Among them, it is preferable to use High Call K-160, High Call K-230, High Call K-290, High Call K-350 (all manufactured by Kaneda Corporation), and High Call K-230, High Call K-290 (all Kaneda Corporation). Is particularly preferable.

The type of liquid paraffin can be appropriately selected depending on the combination with the coated metal particles (A) to be dispersed. For example, when the coated metal particles (A) have a relatively long aliphatic hydrocarbon group and the coated metal particles (A) have a relatively high sintering temperature, it is preferable to use liquid paraffin having a relatively high kinematic viscosity. .. When such liquid paraffin is used, the coated metal particles (A) are sintered while being dispersed in the liquid paraffin, so that a more uniform and high-strength joined body can be formed. On the other hand, when the coated metal particles (A) have a relatively short aliphatic hydrocarbon group and the coated metal particles (A) have a relatively short sintering temperature, it is preferable to use liquid paraffin having a relatively short kinematic viscosity. .. When such liquid paraffin is used, the liquid paraffin can be volatilized at a relatively low temperature, so that the joined body can be formed more efficiently.

When the bonding composition of the present embodiment contains liquid paraffin, the content ratio of the liquid paraffin with respect to the coated metal particles (A) is not particularly limited, but is preferably 0.1% by mass or more, and 1% by mass or more. Is more preferable. Under such conditions, the coated metal particles (A) are well dispersed by the liquid paraffin. The content ratio of liquid paraffin with respect to the coated metal particles (A) is preferably 50% by mass or less, more preferably 30% by mass or less. Under such conditions, the concentration of the coated metal particles (A) is sufficiently maintained, so that high bonding strength can be realized.

(Antioxidant)
The bonding composition according to the present embodiment may contain an antioxidant for the purpose of suppressing the oxidation of the coated metal particles (A). Examples of the antioxidant include phenolic antioxidants such as tocopherol and hydroquinones, phosphorus antioxidants, sulfur antioxidants, amine antioxidants, and the like, and are selected from these. It is preferable to use one kind or a mixture of two or more kinds thereof. Above all, it is more preferable to use a phenolic antioxidant from the viewpoint of compatibility with the solvent (B), and it is even more preferable to use tocopherol.

The proportion of the antioxidant contained in the bonding composition of the present embodiment is not particularly limited, but for example, it is preferably 0.0001 mass% to 20 mass% with respect to 100 mass% of liquid paraffin, The amount is more preferably 0005% by mass to 20% by mass, and even more preferably 0.0005% by mass to 10% by mass.

(Dispersant)
The bonding composition according to the present embodiment may contain a known dispersant such as a polyester dispersant or a polyacrylic acid dispersant. However, from the viewpoint of maintaining the bonding strength, the content of the dispersant contained in the bonding composition is preferably 0.3% by mass or less of the total amount, and more preferably 0.1% by mass or less of the total amount. Even more preferably, the dispersant is not substantially contained. The term "substantially free of dispersant" means, for example, that the dispersant content is 0.01% by mass or less based on the total amount, and preferably that it is below the detection limit in gel permeation chromatography measurement.

(Thickener/gelling agent)
The bonding composition according to the present embodiment may contain a known thickener such as a polymethacrylic acid thickener.
In addition, the bonding composition according to the present embodiment, when containing liquid paraffin, aims to improve the performance of retaining the pattern shape of the coating film before sintering (hereinafter sometimes referred to as “pattern retention”). Then, a gelling agent for gelling the liquid paraffin may be contained. Examples of the gelling agent include polyolefins such as polyethylene, polypropylene, polybutylene, polyisobutylene, and polymethylpentene, and it is preferable to use one kind or a mixture of two or more kinds selected from these, among which polyethylene is used. It is more preferable to use. The weight average molecular weight of the polyolefin is not particularly limited, but can be appropriately selected from, for example, 10,000 or more, and is preferably 10,000 to 5,000,000, and preferably 20,000 to 3,000. 1,000 is more preferable.

When the bonding composition contains a gelling agent, the mixture of liquid paraffin and the gelling agent preferably has thixotropy from the viewpoint of enhancing the pattern retention. The thixo ratio at 25° C. of the mixture of liquid paraffin and gelling agent is preferably 1.2 or more, more preferably 1.5 or more, and further preferably 2.0 or more.
The thixotropic ratio of the mixture of liquid paraffin and gelling agent is a ratio of viscosities measured at different rotation speeds by an E-type viscometer, and is calculated as (viscosity at 10 rpm)/(viscosity at 100 rpm).
Further, the mixing ratio of the liquid paraffin and the gelling agent may be appropriately adjusted within the range where desired physical properties are obtained. In the case where the bonding composition contains a gelling agent, from the viewpoint of improving the pattern retention, the gelling agent is 0.1% by weight based on 100% by mass of the liquid paraffin and the gelling agent contained in the bonding composition. It is preferably 5% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 15% by mass or less, and even more preferably 1.5% by mass or more and 12% by mass or less.

[Use of the bonding composition]
Since the bonding composition of the present invention forms a bonded body having excellent bonding strength, it can be used for bonding a plurality of objects to be bonded. Further, since the bonded body has excellent conductivity, it can be used, for example, for the purpose of electrically bonding the base material and the element. Furthermore, since the bonding composition of the present invention is non-volatile at room temperature, drying is suppressed even if it is left in a state of being coated on a substrate, for example. That is, the bonding composition of the present invention is easy to handle in a process such as screen printing and can be suitably used as a conductive ink.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

<SEM image observation>
Measuring device: JEOL FE-EPMA JXA-8500F
Measurement conditions: acceleration voltage 15 to 20 kV
Observation magnification ×1,500 to ×30,000

<Calculation of average primary particle size and fluctuation rate>
Measuring device: JEOL FE-EPMA JXA-8500F
Average primary particle size: average value of 20 samples Variability: standard deviation of 20 samples/value calculated by average value

<Thermogravimetric/differential heat (TG-DTA) analysis>
Measuring device: Rigaku TG8120
Temperature rising rate: 10°C/min
Measurement temperature range: 25-500°C
Measurement atmosphere: Nitrogen (250 ml/min)

<Powder X-ray diffraction (XRD) analysis>
Measuring device: Rigaku Smartlab
Tube voltage: 45kV
Tube current: 200mA

[Production of Coated Metal Particles and Bonding Composition]
(Production Example 1) Production of Coated Copper Particles Cu1 A 3000 mL glass four-necked flask equipped with a stirrer, a thermometer, a reflux cooling tube, and a nitrogen introduction tube was placed in an oil bath at 150°C.
In the flask, 484 g (3.1 mol) of copper formate anhydride, 98 g of caprylic acid (manufactured by Kanto Chemical Co., Inc.) (0.2 equivalent/copper formate anhydride), and tripropylene as a medium (auxiliary medium) 150 g (0.2 equivalents/copper anhydride) of glycol monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) and petroleum-based hydrocarbon (C9 alkylcyclohexane mixture) as a medium (main medium) (“Swaclean 150” manufactured by Gordo). )) 562 g (1.4 eq/copper formate anhydride) was charged. Under a nitrogen atmosphere, the contents in the flask were heated with an oil bath and mixed until the liquid temperature reached 50° C. with stirring.
712 g (3.0 equivalents/copper formic anhydride) of 3-amino-1-propanol (manufactured by Tokyo Chemical Industry Co., Ltd.) was slowly added dropwise to the above mixture as a complexing agent. After the dropping was completed, the contents of the flask were heated in an oil bath and mixed while stirring until the liquid temperature reached around 120°C. As the liquid temperature increased, the reaction liquid changed from dark blue to dark brown, and carbon dioxide gas foamed. The reaction was terminated when the bubbling of carbon dioxide gas stopped, the oil bath temperature control was stopped, and the mixture was naturally cooled to room temperature.
1200 g of methanol (manufactured by Kanto Chemical Co., Inc.) was added to and mixed with the above reaction liquid cooled to room temperature. After leaving the obtained mixed liquid for 30 minutes or more, the supernatant was decanted to obtain a precipitate. To the precipitate, 1200 g of methanol (manufactured by Kanto Chemical Co., Inc.) and 390 g of acetone (manufactured by Kanto Chemical Co., Ltd.) were added and mixed. After leaving the obtained mixed liquid for 30 minutes or more, the supernatant was decanted to obtain a precipitate. These operations (addition of methanol and acetone and decantation) were repeated once more.
The obtained precipitate was transferred to a 500 mL eggplant flask using 400 g of methanol (manufactured by Kanto Chemical Co., Inc.). After allowing this to stand for 30 minutes or more, the supernatant was decanted.
To the obtained precipitate, 18 g of 3-hydroxy-2,2,4-trimethylpentyl isobutyrate was added and mixed. Then, the eggplant flask was placed in a rotary evaporator, and the contents were dried under reduced pressure (vacuum drying). After drying under reduced pressure (vacuum drying), the mixture was naturally cooled to room temperature, and then the inside of the eggplant flask was purged with nitrogen to release the reduced pressure. As described above, 200 g of brownish brown viscous coated copper particles Cu1 were obtained.

(Production Example 2) Production of coated copper particles Cu2 Production Example 1 except that caprylic acid was changed to 68 g of lauric acid (manufactured by Kanto Chemical Co., Inc.) (0.1 equivalent to copper formate anhydride). In the same manner as in 1., 200 g of brownish brown viscous coated copper particles Cu2 were obtained.

(Production Example 3) Production of coated copper particles Cu3 In Production Example 1, the amount of caprylic acid was 31.8 g, the amount of petroleum hydrocarbon (Swaclean 150) was 279 g, and the amount of tripropylene glycol monomethyl ether was 74. In the same manner as in Production Example 1 except that the amount of 3-amino-1-propanol was changed to 354 g, to 0.3 g, 200 g of brownish brown viscous coated copper particles Cu3 were obtained.

(Production Example 4) Production of coated silver particles Ag1 A 300 mL eggplant flask made of glass equipped with a stirrer bar, a thermometer, and a reflux condenser was placed in an oil bath at 100°C.
In the flask, 30 g (0.1 mol) of silver oxalate anhydride, 6 g of undecanoic acid (manufactured by Kanto Chemical Co., Inc.) (0.3 equivalent/silver oxalate anhydride), and as a medium (auxiliary medium) Tripropylene glycol monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) 10 g (0.5 equivalent/silver oxalate anhydride) and petroleum hydrocarbon (C9 alkylcyclohexane mixture) as a medium (main medium) (manufactured by Gordo Co., Ltd. (Swaclean 150") 54 g (4.3 equivalents/anhydrous silver oxalate) were charged. Under a nitrogen atmosphere, the contents in the flask were heated with an oil bath and mixed with stirring until the liquid temperature reached 50°C.
To the above mixture, 52 g (7.0 equivalents/silver oxalate anhydrous) of 3-amino-1-propanol (manufactured by Tokyo Chemical Industry Co., Ltd.) was slowly added dropwise as a complexing agent. After the completion of the dropping, the contents of the flask were heated in an oil bath and mixed while stirring until the liquid temperature reached around 85° C., and further heating and stirring at this temperature were continued. After 3 hours from the end of the dropping, the heating of the oil bath was stopped to end the reaction, and the reaction solution was naturally cooled to room temperature.
To the above reaction liquid cooled to room temperature, 160 g of methanol (manufactured by Kanto Chemical Co., Inc.) was added and mixed. After leaving the obtained mixed liquid for 30 minutes or more, the supernatant was decanted to obtain a precipitate. 80 g of methanol (manufactured by Kanto Chemical Co., Inc.) and 80 g of acetone (manufactured by Kanto Chemical Co., Ltd.) were added to and mixed with the above precipitate. After leaving the obtained mixed liquid for 30 minutes or more, the supernatant was decanted to obtain a precipitate. These operations (addition of methanol and acetone and decantation) were repeated once more.
To the obtained precipitate, 80 g of methanol (manufactured by Kanto Chemical Co., Inc.) and 1.7 g of 3-hydroxy-2,2,4-trimethylpentyl isobutyrate were added and mixed. This was placed in an eggplant-shaped flask, placed in a rotary evaporator, and the contents were dried under reduced pressure (vacuum drying). After drying under reduced pressure (vacuum drying), the mixture was naturally cooled to room temperature, and then the inside of the eggplant flask was purged with nitrogen to release the reduced pressure. As described above, 18 g of silver-colored coated silver particles Ag1 were obtained.

(Evaluation of coated metal particles)
The physical properties of the coated metal particles were evaluated by TG-DTA analysis, XRD analysis and SEM image observation.

(Example 1)
First, 0.4 part by mass of liquid paraffin (High Coal K-230: manufactured by Kaneda Co., Ltd.) and 0.05 part by mass of n-decanal (manufactured by Tokyo Kasei Co., Ltd.) were mixed, and a stirrer (Awatori Kentaro) (ARE-310): manufactured by Shinky Co., Ltd.) and stirred for 30 seconds at a rotation speed of 2000 rpm.
Next, 4 parts by mass of copper powder (1050Y: manufactured by Mitsui Mining & Smelting Co., Ltd.) having an average particle diameter of 0.5 μm was mixed, and stirring was performed twice at a rotation speed of 2000 rpm for 30 seconds using the above stirrer.
Next, 5.4 parts by mass of coated metal particles (coated copper particles Cu1 obtained in Production Example 1) and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (Kyowanol M:KH). 0.6 parts by mass (Neochem Co., Ltd.) was mixed, and stirring was performed three times at a rotation speed of 2000 rpm for 30 seconds using the above stirrer.
Then, a nylon mesh having a spread of 15 μm was placed on a container (160 ml of Nanko Black: manufactured by Kinki Kako Co., Ltd.), the stirred mixture was placed on the mesh, and then the mixture was stirred at a rotation speed of 2000 rpm for 15 minutes using the above stirrer. It was stirred for 2 seconds, and mesh filtration was performed. As described above, the bonding composition of Example 1 was obtained. The obtained bonding composition was excellent in dispersibility.

(Examples 2 to 4)
The bonding compositions of Examples 2 to 4 were obtained in the same manner as in Example 1 except that the components and blending amounts were changed as shown in Table 1 below. The obtained bonding composition was excellent in dispersibility.
The “copper powder (0.2 μm)” in Table 1 is a copper powder having an average particle diameter of 0.2 μm (1020Y: manufactured by Mitsui Mining & Smelting Co., Ltd.).
High Coal K-230 and High Coal K-290 (both manufactured by Kaneda Co., Ltd.) in Table 1 each contain 99.99995% by mass of liquid paraffin and 0.0005% by mass of tocopherol. The density of Hicol K-230 is 0.835 to 0.855 g/cm ³ at 15°C, and the kinematic viscosity is 11.7 to 15.7 mm ² /s at 37.8°C. Further, the density of High Coal K-290 is 0.850 to 0.865 g/cm ³ at 15°C, and the kinematic viscosity is 159.2 to 175 mm ² /s at 37.8°C.

(Examples 5 and 9)
When blending 0.6 parts by mass of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, 0.25 parts by mass of n-decanol (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) were blended together. Except for the above, the bonding compositions of Examples 5 and 9 were obtained by the same procedure as in Example 1. The obtained bonding composition was excellent in dispersibility.

(Example 6)
The bonding composition of Example 6 was prepared in the same procedure as in Example 5 except that 0.05 part by mass of n-dodecanal (manufactured by Tokyo Kasei Co., Ltd.) was added instead of 0.05 part by mass of n-decanal. Got The obtained bonding composition was excellent in dispersibility.

(Example 7)
Bonding of Example 7 was performed in the same procedure as in Example 5 except that 0.05 part by mass of octanoic acid (Lunack 8-98: manufactured by Kao Corporation) was added instead of 0.05 part by mass of n-decanar. A composition for use was obtained. The obtained bonding composition was excellent in dispersibility.

(Example 8)
0.5 parts by mass of butyl carbitol (manufactured by Gordo Co., Ltd.) was used when 0.6 parts by mass of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate was compounded without compounding liquid paraffin. A bonding composition of Example 8 was obtained by the same procedure as in Example 5 except that the composition was further added. The obtained bonding composition was excellent in dispersibility.

(Example 10)
Coated silver particles Ag1 were used instead of the coated copper particles Cu1, and silver powder having an average particle diameter of 1 μm (SL01: manufactured by Mitsui Mining & Smelting Co., Ltd.) was used instead of the copper powder, in the same procedure as in Example 1. Thus, the bonding composition of Example 10 was obtained. The obtained bonding composition was excellent in dispersibility.

(Example 11)
The bonding composition of Example 11 was prepared in the same procedure as in Example 8 except that the coated silver particles Ag1 were used instead of the coated copper particles Cu1, and the silver powder having an average particle diameter of 1 μm was used instead of the copper powder. Got The obtained bonding composition was excellent in dispersibility.

(Comparative Examples 1 to 6)
The bonding compositions of Comparative Examples 1 to 6 were obtained in the same procedure as in Example 1 except that the components and blending amounts in Example 1 were changed as shown in Table 2 below. In Table 2, n-heptanal is manufactured by Tokyo Kasei Co., Ltd., and isophthalaldehyde is manufactured by Tokyo Kasei Co., Ltd. SC-0708A is a dispersant manufactured by NOF CORPORATION.

<Left stability evaluation>
A syringe (using a clear syringe of 3 cc and a plunger for 3 cc (yellow): all manufactured by Musashi Engineering Co., Ltd.) was filled with the bonding composition of each of Examples 1 to 11 and Comparative Examples 1 to 6, and a needle was filled. (20-22G: Musashi Engineering Co., Ltd.), using an air dispenser (ML5000XII: Musashi Engineering Co., Ltd.), on the Au-plated surface of a 5 mm×5 mm×500 μm silicon substrate (Ti/Ni/Au plating). 2 to 4 mg was applied. Then, a 2 mm×2 mm×500 μm silicon chip (Ti/Ni/Au plating) is placed on the bonding composition so that the Au plating surface is in contact, and the distance between the silicon substrate and the silicon chip is 50 μm. Crimped to.
After that, the silicon substrate and the silicon chip were heated at 100° C. for 60 minutes by using an electric furnace (KDF900GL: manufactured by Denken High Dental Co., Ltd.). Then, the temperature was further raised to a predetermined sintering temperature at a rate of 10° C./minute, and heating was performed at the sintering temperature for 60 minutes to obtain a joined body.
The sintering temperature was 350° C. for the bonding compositions of Examples 1-8 and Comparative Examples 2-4, and 250° C. for the bonding compositions of Example 11, Comparative Examples 1, 5-6. .. Further, the bonding compositions of Examples 9 and 10 were sintered at both sintering temperatures of 250°C and 350°C. Note that nitrogen gas was continuously supplied at a flow rate of 5 L/min from the time when the heating of the coating film was started until the time when the inside of the electric furnace was cooled to 50°C.

Die shear tests were performed on the bonded bodies formed using the bonding compositions of Examples 1 to 11 and Comparative Examples 1 to 6 using a bond tester (Condor Sigma: manufactured by XYZTEC of the Netherlands) to measure the bonding strength. did. The results are shown in Tables 3 and 4. In Tables 3 and 4, “⊚” indicates that the joining strength is particularly high, “◯” indicates that the joining strength is high, and “x” indicates that the joining strength is low.

[Summary of results]
As shown in Table 3, it was found from the results of the bonding strength evaluation that the bonding compositions according to the present invention each exhibit sufficient bonding strength. This indicates that the bonding composition according to the present invention was excellent in bonding strength.

In addition, comparing Examples 5 and 6, the bonding body using the bonding composition containing n-decanal (Example 5) was bonded using the bonding composition containing n-dodecanal (Example 6). The joint strength was particularly high compared to the body. This shows that the joining strength of the joined body is improved by using n-decanal among the aliphatic aldehyde solvents.

Further, among Examples 1 to 11, the examples using liquid paraffin (Examples 1 to 5, 7, 9, and 10) were compared with the examples not using liquid paraffin (Examples 8 and 11). Particularly high bonding strength was exhibited. It is considered that this is because the liquid paraffin improved the dispersibility of the coated metal particles and the metal powder.

From the above results, metal powder and one or more coating molecules selected from a plurality of aliphatic carboxylic acids (A1) and aliphatic aldehydes (A2) on the surface of metal core particles having a smaller particle size than the metal powder. Of the coated metal particles (A) having a density of 2.5 to 5.2 molecules/nm ² , an aliphatic carboxylic acid solvent (B1) having a boiling point of 160° C. or higher and 300° C. or lower, and a boiling point of 160° C. or higher 300 It was shown that the bonding composition containing one or more solvents (B) selected from aliphatic aldehyde solvents (B2) at a temperature of not higher than 0° C. forms a bonded body having excellent bonding strength.

Claims (3)

Metal powder,
2.5 to 5.2 molecules of one or more kinds of coating molecules selected from a plurality of aliphatic carboxylic acids (A1) and aliphatic aldehydes (A2) are provided on the surface of the metal core particles having a smaller particle size than the metal powder. Coated metal particles (A) coated at a density of /nm ² ;
One or more solvents (B) selected from an aliphatic carboxylic acid solvent (B1) having a boiling point of 160° C. or higher and 300° C. or lower and an aliphatic aldehyde solvent (B2) having a boiling point of 160° C. or higher and 300° C. or lower; Containing,
Composition for bonding. The aliphatic aldehyde solvent (B2) contains decanal,
The bonding composition according to claim 1. The aliphatic carboxylic acid solvent (B1) contains octanoic acid,
The bonding composition according to claim 1 or 2.