TW201538537A - Bonding material containing metal nanoparticles - Google Patents

Abstract

The present invention addresses the problem of providing a material that achieves sufficient bonding strength at a low bonding temperature without application of a pressure. This problem is solved by providing a bonding material which is characterized by containing: metal nanoparticles (B) to which a polyethylene glycol-containing organic compound (A) having 8-200 carbon atoms is complexed; and at least one solvent (C) selected from the group consisting of an alcohol solvent having a boiling point of 150 DEG C or more, an ether solvent having a boiling point of 150 DEG C or more, an ester solvent having a boiling point of 150 DEG C or more and a lactam structure-containing solvent having a boiling point of 150 DEG C or more.

Description

Bonding material containing metal nanoparticles

The present invention relates to a bonding material using metal nanoparticles having a particle diameter of 1 to 100 nm as a main component of bonding.

From the point of view of environmental protection, there is a wide range of industrial restrictions on the use of hazardous substances, especially for installation materials, based on the implementation of the EU RoHS Directive, and continue to strongly promote the lead-free solder. As a result, a tin-silver-based or tin-copper-based solder was found as a bonding material in place of the conventional tin-lead eutectic solder (melting point: 183 ° C), and it was widely used (melting point: 220 to 230 ° C). However, in applications requiring heat resistance and heat transfer, for example, the use of a power device for controlling a large current to be bonded to a heat sink base, reliability under high temperature conditions around 250 ° C is required, but the actual situation has not been found. A bonding material containing a high tin content of a tin-lead alloy (melting point of 238 ° C) is still used (Non-Patent Document 1).

As a joining method which does not use the heat resistance of lead, it is desirable to use the joining technique of a metal nanoparticle. Since the metal nanoparticles of 100 nm or less have a particularly high specific surface area per unit weight as compared with the bulk metal, they are fused to each other to lower the surface energy, and the particles can be at a very low temperature compared with the bulk metal. Fuse each other. The use of a phenomenon known as the quantum size effect (the Kubo effect), the solder particles are micronized to the extent that the melting point is lowered, and a bonding material for silver nanoparticles fused at a temperature of 350 ° C under no pressure is developed. (Patent Document 1). When metal nanoparticle is used as a material for bonding, it is a lead-free bonding technique. Therefore, the industry is investigating a bonding method using silver nanoparticles and bonding. The practical use of the product.

If it is made into a bulk metal by heating, a relatively high temperature (the melting point of the bulk metal) is required to be melted again, so that the joining using the metal nanoparticle can be expected to be higher at a high temperature of 250 ° C or higher. reliability. That is, it is suitable for the soldering of the above-mentioned power semiconductor, or the solder for circuit mounting used in a high-temperature environment like an engine room of an automobile. Since the melting does not occur when the melting point of the bulk material is reached, the property of the joint stabilization is also practically useful in the case of secondary mounting. It is expected to be applied to the assembly of power semiconductor devices for hybrid electric vehicles.

However, in the joining using metal nanoparticles, heating at about 300 ° C is required, and at this temperature, peripheral parts may be warped or bent. Therefore, in order to perform bonding by the existing steps, it is necessary to achieve 200 under no pressure. Low temperature bonding at temperatures below °C. There is also a report that the bonding temperature is lowered to 300 ° C or lower by adding a flux such as oxydiacetic acid. However, it is necessary to subject the bonded substrate to silver plating or the like, which results in poor practicability (Patent Document 2). Moreover, as a low-temperature bonding example of 200 ° C or less, there is a report that a composite composition obtained by combining a copolymer of a polyethylenimine and a polyethylene glycol with a silver nanoparticle is used as a bonding agent (patent Document 3), but requires a pressurization of about 2.5 MPa, and the joint strength test method is a scotch tape peeling test or the like, but it is difficult to say that it satisfies the performance of a practical power semiconductor manufacturing step.

On the other hand, the above-mentioned silver has a drawback that ion migration easily occurs and is likely to be a cause of short-circuiting of the wiring, and since it is a noble metal, it is extremely difficult to achieve a low price. Therefore, the industry has begun to study a bonding method using copper nanoparticles and a bonding article (Patent Documents 4 to 5).

The bonding material of Patent Document 4 is characterized in that copper nanoparticles and silver nanoparticles are used in combination, and each metal of the metal nanoparticles is protected by a low molecular amine. Since the interaction between the low molecular amine and the metal nanoparticle is strong, the low molecular amine does not desorb from the nano metal as long as it is not a high temperature condition, and the nano metal cannot be sufficiently sintered. Therefore, in order to obtain To achieve sufficient joint strength, it is required to be joined under high temperature conditions at 350 ° C under atmospheric conditions.

Further, the bonding material of Patent Document 5 is characterized in that the copper nanoparticle having the adjusted particle size distribution has an effect of imparting oxidation resistance to the copper nanoparticle itself, but the storage stability of the bonding material itself is insufficient. A dispersion stabilizer must be added. In order to ensure sufficient bonding strength in the presence of a dispersion stabilizer, bonding is carried out at a high temperature of 300 ° C to 400 ° C in a hydrogen atmosphere as a reducing gas, but it is not practical.

In addition, as a metal nanoparticle binder, a low molecular protection agent having an alkyl chain of about C ₈ to C ₁₂ as a dispersion site and having an amine or a carboxylic acid as a metal coordination site at the terminal is widely used (Patent Document 6). . When a metal nanoparticle using such a low molecular weight protecting agent is used as a material for bonding, a flux is added as a reducing agent in order to reduce and remove an extremely thin metal oxide layer on the surface of the metal nanoparticle. However, the alkyl chain in the protective agent does not undergo decomposition and volatilization at a low temperature of 200 ° C or lower, and remains on the surface of the metal nanoparticles, which hinders the reduction effect of the flux, making it difficult to achieve low temperature bonding.

On the other hand, the bonding of the metal nanoparticles using a phosphate-based protective agent having a hydrophilic portion has been studied, but the removal of the metal oxide film is insufficient, and the bonding at a low temperature of 200 ° C cannot be achieved (Patent Document 7).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] International Publication No. 2011/155615

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2011-240406

[Patent Document 3] Japanese Patent Laid-Open No. 2011-046770

[Patent Document 4] Japanese Patent Laid-Open No. 2011-058041

[Patent Document 5] Japanese Patent Laid-Open Publication No. 2013-091835

[Patent Document 6] International Publication No. 2011/007402

[Patent Document 7] Japanese Patent Laid-Open Publication No. 2013-004309

[Non-patent literature]

[Non-Patent Document 1] Japanese Industrial Standard JIS Z 3282 (Solder - Chemical Composition and Shape, 2006)

As described above, silver nanoparticles have a problem of migration and low price, and copper nanoparticles have a problem of bonding under high temperature conditions due to oxidation resistance, but they can be used as high effective depending on the intended use. Heat resistant bonding agent.

However, silver and copper nanoparticles have high usefulness as a bonding agent for power semiconductors, but cannot achieve low-temperature bonding at 200 ° C or lower, which is a hindrance to practical use. From the above, it is expected that the bonding temperature under low pressure conditions will be lowered.

Therefore, the main object of the present invention is to provide a bonding material which is a metal nanoparticle and which does not impair the dispersion stability of the metal nanoparticle, and can be used under no pressure and below 200 ° C. Bonding is performed at a higher strength at a low temperature.

In view of the above-mentioned actual situation, it has been found that a specific solvent such as an alcohol solvent having a boiling point of 150 ° C or more is introduced by introducing a polyethylene glycol having a carbon number of from 8 to 200 in a dispersed portion of the protective agent. When the flux is not added, the metal oxide thin film layer on the surface of the metal nanoparticles is effectively removed at a low temperature of 200 ° C or lower, thereby completing a metal nanoparticle bonding material capable of achieving high strength bonding.

That is, the present invention relates to a bonding material as follows: Item 1. A bonding material comprising: a metal nanoparticle compounded with an organic compound (A) having a polyethylene glycol having 8 to 200 carbon atoms ( B) and an alcohol-based solvent selected from the group consisting of an alcohol solvent having a boiling point of 150 ° C or higher, an ether solvent having a boiling point of 150 ° C or higher, an ester solvent having a boiling point of 150 ° C or higher, and a solvent containing an internal guanamine structure having a boiling point of 150 ° C or higher. At least one solvent (C) of the composition group; Item 2. The bonding material according to Item 1, wherein the organic compound (A) having a polyethylene glycol having a carbon number of 8 to 200 is represented by the following formula (1) The compound represented by the following formula (2), the compound represented by the following formula (3), or the structure represented by the following formula (4) at least one terminal and the side chain a (meth)acrylic polymer (polymer α) having a polyethylene glycol chain (P), and having a structure represented by the following formula (4) at at least one terminal and -OP (O) in a side chain a compound of a (meth)acrylic polymer (polymer β) of a phosphate residue represented by (OH) ₂ , W-(OCH ₂ CH ₂ ) _n -O-CH ₂ -CH(OH) -CH ₂ -SX (1)

[W-(OCH ₂ CH ₂ ) _n -O-CH ₂ -CH(OH)-CH ₂ -S-] _d Y (2)

[W-(OCH ₂ CH ₂ ) _n -O-CH ₂ -CH(OH)-CH ₂ -SR ^a -] _t Z (3)

[W in the formulas (1), (2) and (3) is an alkyl group of C ₁ to C ₈ , n is an integer of 4 to 100 representing a repeating number, and X is an alkyl group or alkene of C ₂ to C ₁₂ a propyl group, an aryl group, an arylalkyl group, -R ¹ -OH, -R ¹ -NHR ² or -R ¹ -(COR ³ ) _m (wherein R ¹ is a C ₁ -C ₄ saturated hydrocarbon group, R ² a hydrogen atom, a C ₂ -C ₄ fluorenyl group, a C ₂ -C ₄ alkoxycarbonyl group, or an C ₁ -C ₄ alkyl group or a C ₁ -C ₈ alkoxy group as an aromatic ring; a benzyloxycarbonyl group of a substituent, R ³ is a hydroxyl group, a C ₁ -C ₄ alkyl group or a C ₁ -C ₈ alkoxy group, m is an integer of 1 to 3), and a Y system is directly bonded to a sulfur atom. Is a 2-4 valence of a carbon atom, a saturated hydrocarbon group of C ₁ -C ₄ or a saturated hydrocarbon group of 2 to 3 C ₁ -C ₄ using ~O-, -S- or -NHR ^b - (R ^b is C _{a group of 1} to _{4 4} saturated hydrocarbon groups), d is an integer of 2 to 4, R ^a is an alkylcarbonyloxy group of C ₂ to C ₅ , and a Z bond directly bonded to a sulfur atom is a carbon atom. 2~6 valencies, C ₂ ~ C ₆ saturated hydrocarbon groups, 2 ~ 3 C ₂ ~ C ₆ saturated hydrocarbon groups using -O-, -S- or -NHR ^c - (R ^c is C ₁ ~ C ₄ a saturated hydrocarbon group) or a hetero-cyanuric acid-N,N',N"-tri-ethyl group, and t is an integer of 2 to 6]

R-S- (4)

[In the formula (4), R represents a linear or branched alkyl group having 1 to 18 carbon atoms, or has a linear alkoxy group selected from a hydroxyl group and a carbon number of 1 to 18, and has 1 carbon atom; a branched alkoxy group, an aralkyloxy group, a substituted phenoxy group, a linear alkylcarbonyloxy group having 1 to 18 carbon atoms, or a branched alkylcarbonyloxy group having 1 to 18 carbon atoms; a salt of a carboxyl group or a carboxyl group, a linear alkoxycarbonyl group having 1 to 18 carbon atoms, a branched alkoxycarbonyl group having 1 to 18 carbon atoms, a phosphoric acid group or a linear alkyl group having 1 to 6 carbon atoms a phosphate group, a branched alkyl phosphate group having 1 to 6 carbon atoms, a sulfonic acid group, a linear alkylsulfonic acid group having 1 to 6 carbon atoms, and a branched alkyl group having 1 to 6 carbon atoms a linear or branched alkyl group having 1 to 8 carbon atoms of at least one functional group in the group consisting of sulfonic acid groups; Item 3. The bonding material according to Item 1, which contains a carbon number of 8~ The organic compound (A) of the polyethylene glycol of 200 is a compound represented by the following formula (1), a compound represented by the following formula (2) or a compound represented by the following formula (3), -(OCH ₂ CH ₂ ) _n -O-CH ₂ -CH(OH)-CH ₂ -SX (1)

[W-(OCH ₂ CH ₂ ) _n -O-CH ₂ -CH(OH)-CH ₂ -S-] _d Y (2)

[W-(OCH ₂ CH ₂ ) _n -O-CH ₂ -CH(OH)-CH ₂ -SR ^a -] _t Z (3)

[W in the formulas (1), (2) and (3) is an alkyl group of C ₁ to C ₈ , n is an integer of 4 to 100 representing a repeating number, and X is an alkyl group or alkene of C ₂ to C ₁₂ a propyl group, an aryl group, an arylalkyl group, -R ¹ -OH, -R ¹ -NHR ² or -R ¹ -(COR ³ ) _m (wherein R ¹ is a C ₁ -C ₄ saturated hydrocarbon group, R ² a hydrogen atom, a C ₂ -C ₄ fluorenyl group, a C ₂ -C ₄ alkoxycarbonyl group, or an C ₁ -C ₄ alkyl group or a C ₁ -C ₈ alkoxy group as an aromatic ring; a benzyloxycarbonyl group of a substituent, R ³ is a hydroxyl group, a C ₁ -C ₄ alkyl group or a C ₁ -C ₈ alkoxy group, m is an integer of 1 to 3), and a Y system is directly bonded to a sulfur atom. Is a 2 to 4 valent group of a carbon atom, a saturated hydrocarbon group of C ₁ to C ₄ or 2 to 3 saturated hydrocarbon groups of C ₁ to C ₄ using -O-, -S- or -NHR ^b - (R ^b is C _{a group of 1} to _{4 4} saturated hydrocarbon groups), d is an integer of 2 to 4, R ^a is an alkylcarbonyloxy group of C ₂ to C ₅ , and a Z bond directly bonded to a sulfur atom is a carbon atom. 2~6 valencies, C ₂ ~ C ₆ saturated hydrocarbon groups, 2 ~ 3 C ₂ ~ C ₆ saturated hydrocarbon groups using -O-, -S- or -NHR ^c - (R ^c is C ₁ ~ C ₄ a saturated hydrocarbon group), or an iso-cyanuric acid-N,N',N"-tri-ethyl group, t is an integer from 2 to 6]; Item 4. a mixed material, wherein the solvent (C) is at least one selected from the group consisting of an alcohol solvent having a boiling point of 150 ° C or higher and an ether solvent having a boiling point of 150 ° C or higher; and the bonding material of item 1. , wherein the metal nanoparticle (B) is a silver nanoparticle, a copper nanoparticle, a silver core copper nanoparticle or a copper core silver nanoparticle; or the bonding material according to item 1, wherein the above In the metal nanoparticle, the content of the organic compound (A) having a polyethylene glycol having a carbon number of 8 to 200 is 2 to 15% by mass; the bonding material according to any one of items 1 to 6, The joined object to be joined is a metal or a metal oxide.

According to the present invention, the joining can be carried out at a relatively high strength under a low temperature condition of no pressure and 200 ° C or lower.

Next, an embodiment of the present invention will be described.

<Metal species in metal nanoparticles>

The metal species of the metal nanoparticles (B) of the present invention is not particularly limited as long as it can be compounded with the following polyethylene glycol-containing organic compound, and is preferably copper (Cu) or silver (Ag). . Examples of the copper-based and silver-based nanoparticles include copper nanoparticles, silver nanoparticles, silver core copper nanoparticles, and copper core silver nanoparticles. Among them, copper nanoparticles are more preferred.

<Organic compound containing polyethylene glycol>

The polyethylene glycol moiety in the protective agent (polyethylene glycol-containing organic compound) used in the present invention is excellent in affinity with a specific solvent of the present invention such as an alcohol solvent having a boiling point of 150 ° C or higher, and thus can be strongly suppressed. The agglomeration of the metal nanoparticles allows a high degree of dispersion of the metal nanoparticles. That is, since the metal nanoparticles are in a state of being filled at a high density, they are not accompanied by the decomposition and removal of the protective agent and the solvent due to the heat treatment. The voids are generated to achieve high-density bonding due to the necking phenomenon of the metal particles, thereby achieving high-strength bonding under no-pressurization conditions. Further, the metal nanoparticles synthesized by using the protective agent of the present invention have a small amount of the protective agent, and are about 2 to 15%, which does not hinder the necking phenomenon of the metal particles at the time of joining, and is almost after the joining. Since the organic component does not remain, it has high reliability as a highly heat-resistant bonding agent.

An example of a metal nanoparticle compounded with an organic compound containing a polyethylene glycol having 8 to 200 carbon atoms contained in the bonding material of the present invention can be obtained by Japanese Patent No. 4784847 and Japanese Patent Laid-Open Publication No. 2013 It is synthesized by the method described in Japanese Patent No. 6063728 or Japanese Patent No. 5077728. These characteristics are characterized in that the thioether type (RS-R') compound has an appropriate affinity adsorption effect on the surface of the metal particles and rapid desorption by heating, and is developed as a metal nanoparticle exhibiting low-temperature fusion characteristics. come out.

In addition, as another example, a polymer having a polyethylene glycol having a carbon number of 8 to 200 in a polymer compound having a thioether group, which is described in JP-A-2010-209421, is exemplified. a metal nanoparticle of a compound; further, a polyethylene glycol having a carbon number of 8 to 200 in a polymer compound having a thioether group and having a phosphate group as described in Japanese Patent No. 4,697,356 Metal nanoparticles such as polymer compounds. The production of these polyethylene glycol-containing polymer compounds can be carried out in accordance with the methods described in these publications. Further, in the present invention, the polyethylene glycol-containing phosphate type organic compound has a thioether group and also has a phosphate group, and by having such a group, an appropriate affinity adsorption to the surface of the metal nanoparticles can be imparted. The effect, and rapid desorption by heating.

Among these, a thioether type organic compound represented by the following formulas (1) to (3) is preferable.

<thioether (R-S-R') type organic compound>

As an example of the effect of the present invention, copper-based and silver-based nanoparticles in which a thioether-type organic compound represented by the following general formulae (1) to (3) are combined will be described in detail.

W-(OCH ₂ CH ₂ ) _n -O-CH ₂ -CH(OH)-CH ₂ -SX (1)

[W-(OCH ₂ CH ₂ ) _n -O-CH ₂ -CH(OH)-CH ₂ -S-] _d Y (2)

[W-(OCH ₂ CH ₂ ) _n -O-CH ₂ -CH(OH)-CH ₂ -SR ^a -] _t Z (3)

[W in the formulas (1), (2) and (3) is an alkyl group of C ₁ to C ₈ , n is an integer of 4 to 100 representing a repeating number, and X is an alkyl group or alkene of C ₂ to C ₁₂ a propyl group, an aryl group, an arylalkyl group, -R ¹ -OH, -R ¹ -NHR ² or -R ¹ -(COR ³ ) _m (wherein R ¹ is a C ₁ -C ₄ saturated hydrocarbon group, R ² a hydrogen atom, a C ₂ -C ₄ fluorenyl group, a C ₂ -C ₄ alkoxycarbonyl group, or an C ₁ -C ₄ alkyl group or a C ₁ -C ₈ alkoxy group as an aromatic ring; a benzyloxycarbonyl group of a substituent, R ³ is a hydroxyl group, a C ₁ -C ₄ alkyl group or a C ₁ -C ₈ alkoxy group, m is an integer of 1 to 3), and a Y system is directly bonded to a sulfur atom. Is a 2 to 4 valent group of a carbon atom, a saturated hydrocarbon group of C ₁ to C ₄ or 2 to 3 saturated hydrocarbon groups of C ₁ to C ₄ using -O-, -S- or -NHR ^b - (R ^b is C _{a group of 1} to _{4 4} saturated hydrocarbon groups), d is an integer of 2 to 4, R ^a is an alkylcarbonyloxy group of C ₂ to C ₅ , and a Z bond directly bonded to a sulfur atom is a carbon atom. 2~6 valencies, C ₂ ~ C ₆ saturated hydrocarbon groups, 2 ~ 3 C ₂ ~ C ₆ saturated hydrocarbon groups using -O-, -S- or -NHR ^c - (R ^c is C ₁ ~ C ₄ a saturated hydrocarbon group) or a hetero-cyanuric acid-N,N',N"-tri-ethyl group, and t is an integer of 2 to 6]

The chain functional group having ethylene glycol as a repeating unit in the above formulas (1) to (3) functions as a solvent affinity portion. The carbon number of the polyethylene glycol is preferably from 8 to 200 carbon atoms, more preferably from 8 to 100 carbon atoms.

Further, in the above-described general formulae (1) to (3), the chain functional group having ethylene glycol as a repeating unit has a smaller carbon number, and the organic component is less likely to remain, so that it is a bonding agent having high reliability. Good carbon number is about 8~12.

On the other hand, in the above-mentioned general formula (1) to (3), a chain functional group having ethylene glycol as a repeating unit, and having a carbon number of about 50 to 100 is excellent in dispersion stability, and is used to make metal nano It is more preferable that the particles are highly dispersed to improve the joint strength under no-pressurization conditions.

Therefore, depending on the use, the carbon number can be appropriately adjusted in the range of 8 to 200, or more preferably in the range of 8 to 100.

With regard to W in the above formulas (1) to (3), it is industrially easy to obtain and used as In terms of dispersion stability in the case of a protective agent, it is a linear or branched alkyl group having 1 to 8 carbon atoms, and particularly preferably a carbon number of 1 to 1 in terms of stability in an aqueous medium. 4 alkyl.

In the above formula (1), the structure in which X contains a carboxyl group, an alkoxycarbonyl group, a carbonyl group, an amine group or a decylamino group as a partial structure becomes a thioether group and a polydentate ligand, and thus It is preferred that the coordination force on the surface of the rice particles becomes strong.

It is most preferable that Y in the above formula (2) contains an ether (COC) or a thioether (CSC) as a partial structure, and R ^a in the above formula (3) is ^a methylene carboxyl group (-CH _{2 )} COO-) or ethyl carboxy group (-CH ₂ CH ₂ COO-) and Z is ethyl, 2-ethyl-2-methylenepropane-1,3-diyl, 2,2-bis-Methylene Propane-1,3-diyl group.

<Method for producing thioether type organic compound>

As described above, in the present invention, the thioether type organic compound is preferably a compound represented by the above formulas (1) to (3). The method for producing these thioether type organic compounds is described in detail below.

As a method of easily producing a thioether type organic compound, for example, a method of reacting a polyether compound (a1) having a glycidyl group at a terminal with a thiol compound (a2) can be mentioned.

The polyether compound (a1) having a glycidyl group at the terminal may be represented by the following formula (5).

(where W, R ¹ , n are the same as above)

As a synthesis method of the polyether compound (a1) having a glycidyl group at the terminal, for example, For example, in the presence of Lewis acid, the polyethylene glycol monoalkyl ether is added to the epichlorohydrin ring of the epichlorohydrin ring, and then the resulting chlorohydrin is heated in a concentrated alkali. a method of reclosing the mixture; a method of performing a reaction in stages using a strong base such as an alcoholate or a concentrated alkali; however, as a method of obtaining a polyether compound (a1) of higher purity, a method using Gandour et al. That is, using polyethylene tert-butoxide to make polyethylene glycol monomethyl ether into an alkoxide and condensing it with epichlorohydrin, heating is continued to form an epoxy ring again (Gandour, et al., J. Org). .Chem., 1983, 48, 1116.).

The terminal oxirane ring of the above polyether compound (a1) having a glycidyl group at the terminal can be opened by a thiol compound (a2) to obtain a target thioether type organic compound. This reaction is a nucleophilic reaction using a thiol group, and various activation methods can be mentioned about this reaction.

For example, synthesis by epoxidation using Lewis acid is widely carried out, and specifically, zinc tartrate or lanthanide Lewis acid is known. Also, the method of using Lewis base is often carried out.

Further, the method of using fluorine ions as a base catalyst has been described in detail in the review by James H. Clark. Penso et al. reported the use of this as a ring opening method for epoxides superior in regioselectivity, and using quaternary ammonium fluoride as a catalyst to carry out thiol pairing under mild conditions. The addition of an oxide is a ring opening reaction.

In particular, in terms of obtaining a thioether type organic compound used in the present invention with high efficiency, a method using a fluoride ion as a base catalyst is preferred. By applying this method, after reacting the polyether compound (a1) having a glycidyl group at the terminal with the thiol compound (a2), a thioether type organic compound can be obtained without special purification.

For the polyether compound (a1), various thiol compounds (a2) can be reacted therewith. As an example, in addition to alkane thiols and thiophenols, thioglycol, thioglycolic acid and esters thereof, which are easily obtained as a radical polymerization chain transfer agent, and mercaptopropionic acid are also exemplified. And esters and the like. It is also possible to react a mercaptopolycarboxylic acid such as thiomalic acid, thiocitric acid or the like. Further, a compound having a plurality of thiol groups in the molecule, that is, an alkyldithiol such as ethanedithiol, trimethylolpropane tris(3-mercaptopropionate), or pentaerythritol IV may be used. 3-mercaptopropionate), dipentaerythritol hexa(3-mercaptopropionate), etc. are similarly reacted and introduced. As a result, since the obtained compound has a plurality of thioether structures in the molecule, the copper-based nanoparticles can exhibit affinity by a plurality of regions.

<Phosphate-type organic compound containing polyethylene glycol>

As an example of the effect of the present invention, copper-based and silver-based nanoparticles in which a phosphate-type organic compound containing polyethylene glycol is compounded will be described in detail.

The compound used in the present invention is a (meth)acrylic polymer (polymer) having at least one terminal having a structure represented by the following formula (4) and having a polyethylene glycol chain (P) in a side chain. And a (meth)acrylic polymer having a structure represented by the following formula (4) and having a phosphate residue represented by -OP(O)(OH) ₂ in a side chain at at least one terminal (Polymer β) compound; RS- (4)

[In the formula (4), R represents a linear or branched alkyl group having 1 to 18 carbon atoms, or has a linear alkoxy group selected from a hydroxyl group and a carbon number of 1 to 18, and has 1 carbon atom; a branched alkoxy group, an aralkyloxy group, a substituted phenoxy group, a linear alkylcarbonyloxy group having 1 to 18 carbon atoms, or a branched alkylcarbonyloxy group having 1 to 18 carbon atoms; a salt of a carboxyl group or a carboxyl group, a linear alkoxycarbonyl group having 1 to 18 carbon atoms, a branched alkoxycarbonyl group having 1 to 18 carbon atoms, a phosphoric acid group or a linear alkyl group having 1 to 6 carbon atoms a phosphate group, a branched alkyl phosphate group having 1 to 6 carbon atoms, a sulfonic acid group, a linear alkylsulfonic acid group having 1 to 6 carbon atoms, and a branched alkyl group having 1 to 6 carbon atoms a linear or branched alkyl group having 1 to 8 carbon atoms of at least one functional group in the group consisting of sulfonic acid groups.

Here, the suitable carbon number for the polyethylene glycol, and the above thioether type organic compound The situation is the same.

<Method for Producing Phosphate Type Organic Compound Containing Polyethylene Glycol>

A thiol compound (Q) which is usually used as a chain transfer agent can be used in order to obtain a thiol compound (Q) which is used for a polymer compound having a structure represented by the formula (4) in the molecule. Specific examples thereof include thioglycol, 2-mercaptopropanol, 3-mercaptopropanol, 8-mercaptooctyl alcohol, 2,3-dihydroxypropyl mercaptan, 2-methoxyethanethiol, 2- Ethoxyethanethiol, 2-hexyloxyethanethiol, 2-(2-ethylhexyloxy)ethanethiol, 2-benzyloxyethanethiol, 2-(4-methoxybenzyloxy) Ethyl mercaptan, 2-phenoxyethanethiol, 2-(4-methoxyphenoxy)ethanethiol, 2-(2,4-dimethoxyphenoxy)ethanethiol, 6-(4-Hydroxymethylphenoxy)hexyl mercaptan, 2-ethoxymethoxyethanethiol, 2-heptyloxyethanethiol, 2-octyloxyethanethiol, 2-eighteen Nonyloxyethanethiol, 2-isobutyloxyethoxyethane, 2-pentyloxyethanethiol, thioglycolic acid, β-mercaptopropionic acid, 7-mercaptooctanoic acid, 2-mercaptopropionic acid , 2-mercaptosuccinic acid, and inorganic salts of these carboxylic acids, salts of ammonium salts and organic amines, methyl thioglycolate, ethyl thioglycolate, octyl thioglycolate, beta-mercaptopropionic acid Ester, octyl β-mercaptopropionate, lauryl β-mercaptopropionate, 2-(methoxyethyl) β-mercaptopropionate, 2-(methoxyethoxy) β-mercaptopropionic acid Ethoxyl ester, β-mercaptopropionic acid 2-(4-methoxy Butoxy)ester, 2-ethylhexyl thioglycolate, 2-ethylhexyl β-mercaptopropionate, 3-methoxybutoxy ester of β-mercaptopropionate, 2-mercaptoethyl phosphate, 2-mercaptoethyl phosphinate, 2-mercaptopropyl phosphate, 2-mercaptopropyl phosphinate, ω-mercaptoethoxyethyl phosphate, ω-mercaptopropyl propyl phosphate, 2-mercaptopropyl phosphate Diester dimethyl ester, 2-mercaptoethyl dimethyl phosphinate, 2-mercaptoethyl phosphate diethyl ester, 2-mercaptopropyl phosphate diethyl ester, 2-mercaptoethyl phosphate diisopropyl phosphate, phosphoric acid 2 - mercaptoethyl diisobutyl ester, 2-mercaptoethyl sulfate, 2-mercaptoethanesulfonic acid, 2-mercaptopropanesulfonic acid, 2-mercaptoethyl sulfate methyl ester, methyl 2-mercaptoethanesulfonate, sulfuric acid 2 - mercapto ethyl ester ethyl ester, ethyl 2-mercaptoethanesulfonate, methyl 2-mercaptopropanesulfonate, ethyl 2-mercaptopropanesulfonate, and the like. Among them, in terms of reactivity, ease of availability, and surface smoothness at the time of film formation, thioglycol, 2,3-dihydroxypropanethiol, thioglycolic acid, and β-mercaptopropionic acid are preferable. Ethyl β-mercaptopropionate, β-mercaptopropyl 2-ethylhexyl acid, most preferably methyl β-mercaptopropionate.

The polymerizable compound which reacts with the above thiol compound (Q) is not particularly limited, and a known polymerizable compound can be used. Specifically, it is a (meth)acrylic acid, a (meth)acrylate compound, a vinyl alcohol ester compound, a styrene compound, an allyl alcohol compound, an allylamine compound, etc.

The protective agent for metal nanoparticles of the present invention is characterized in that a protective agent corresponding to the metal species or desired physical properties can be designed by appropriately selecting a polymerizable compound containing a functional group having affinity with a metal. . Specifically, it can exhibit a moderate degree of interaction by using a carboxyl group, a phosphate group, a sulfonic acid group or a heterocyclic aromatic group (for example, an imidazolyl group) having a slightly strong adsorption ability with respect to a metal, and according to a dispersion medium An amine group (such as dimethylaminoethyl, dimethylaminopropyl) whose acidity is alkaline and whose adsorption capacity changes, and the interaction with the metal surface is smaller than the former hydroxyl group (hydroxyethyl group, hydroxypropyl group) a polymerizable compound of an aromatic group (for example, a benzyl group), and the functional group is freely provided to the metal nanoparticle protective agent, and since the ratio can be freely changed, the adsorptivity can be freely change.

For example, as the polymerizable compound, a polymerizable compound having a polyethylene glycol chain such as a polyalkylene glycol methacrylate can be used, and the structure represented by the above formula (4) is high in the molecule. A polyethylene glycol chain is incorporated into the molecular compound.

Further, in the same manner, as the polymerizable compound, a carboxyl group can be introduced by using (meth)acrylic acid or the like, and an amine group can be introduced by using dimethylaminoethyl methacrylate or the like, and a phosphate group can be used. A phosphoric acid group can be introduced by using a acryloyloxyethyl ester or the like, and a hydroxyl group can be introduced by using hydroxyethyl methacrylate or the like, and a modified (meth) acrylate having a sulfonic acid group can be used as a polymerizable compound. The introduction of a sulfonic acid group can introduce a heteroaromatic group by using a heteroaromatic vinyl compound. In this way, an amine group, a carboxyl group, an imidazole group, a phosphate group, a sulfonic acid group or the like can be incorporated into the polymer compound having a structure represented by the above formula (4) in the molecule.

Specific examples of the polymerizable compound include 2-dimethylaminoethyl methacrylate, vinylimidazole, 2-methylpropenyloxyethyl phosphate, and 2-propenylamine-2- Methyl propane sulfonic acid.

The polymerization method of the protective agent for metal nanoparticles of the present invention may be a usual radical polymerization method, as long as the thiol compound and the polymerizable compound are dissolved in a suitable solvent, and a peroxycarboxylic acid ester or the like is added as a polymerization initiation. The agent can be heated.

<Synthesis of copper or silver nanoparticles coated with an organic compound containing polyethylene glycol having a carbon number of 8 to 200>

As an example of the effect of the present invention, the method for producing metal nanoparticles containing an organic compound containing polyethylene glycol having 8 to 200 carbon atoms contained in the bonding material of the present invention is characterized by comprising the following steps: The divalent copper ion compound or the monovalent silver ion compound is mixed with a solvent in the presence of a thioether type organic compound; and copper ions or silver ions are reduced.

As the divalent copper ion compound, a copper compound which is usually available can be used, and a sulfate, a nitrate, a carboxylate, a carbonate, a chloride, an acetylpyruvate complex or the like can be used. In the case of obtaining a composite with zero-valent copper nanoparticles, a divalent compound may be used as a starting material, a monovalent compound may be used, or water or water of crystallization may be used. Specifically, when crystallization water is removed, CuSO ₄ , Cu(NO ₃ ) ₂ , Cu(OAc) ₂ , Cu(CH ₃ CH ₂ COO) ₂ , Cu(HCOO) ₂ , CuCO ₃ , CuCl ₂ , Cu ₂ O, C ₅ H ₇ CuO ₂ and the like. Further, an alkaline salt obtained by heating or exposing the above salt to an alkaline atmosphere, such as Cu(OAc) ₂ , can be most suitably used. CuO, Cu(OAc) ₂ . 2CuO, Cu ₂ Cl(OH) ₃ and the like. These basic salts can be prepared in the reaction system or can be used in addition to the reaction system. Further, a general method of adding an ammonia or an amine compound to form a complex to ensure solubility after reduction can also be applied.

As the monovalent silver ion compound, a generally available silver compound can be used, and examples thereof include silver nitrate, silver oxide, silver acetate, silver fluoride, silver acetylacetonate, silver benzoate, and carbon. Silver acetate, silver citrate, silver hexafluorophosphate, silver lactate, silver nitrite, silver pentafluoropropionate, etc., silver nitrate or oxidation is preferred from the viewpoints of ease of handling and ease of industrial availability. silver.

The copper or silver ion compound is dissolved or mixed into a medium in which a thioether type organic compound is previously dissolved or dispersed. In this case, as a usable medium, although it depends on the structure of the organic compound to be used, it is preferred to use a mixture of water, ethanol, acetone, ethylene glycol, diethylene glycol, glycerin or the like, and particularly preferably water. - ethylene glycol mixture.

The concentration of the thioether type organic compound in various media is preferably adjusted to a range of 0.3 to 10% by mass in terms of control of the subsequent reduction reaction.

The above copper or silver ion compound is added and mixed in one or a batch in the medium prepared above. In the case of using a medium which is difficult to dissolve, it may be a method of pre-dissolving in a small amount of a good solvent and then adding it to the medium.

The ratio of use of the mixed thioether type organic compound to the copper or silver ion compound is preferably selected depending on the protective ability of the thioether type organic compound in the reaction medium, but usually per 1 mol of the copper or silver ion compound is used as The thioether type organic compound is prepared in the range of 1 mmol to 30 mmol (about 2 to 60 g when a polymer having a molecular weight of 2000 is used), and particularly preferably used in the range of 15 to 30 mmol.

Then, various reducing agents are used for the reduction of copper or silver ions. As a reducing agent, a ruthenium compound, a hydroxylamine and a derivative thereof, a metal hydride, a phosphinate, an aldehyde, an olefinic diol, a hydroxyketone or the like can be subjected to copper at a temperature below an ice bath cooling temperature of 80 ° C or lower. The compound of the reduction reaction of silver or the like is suitable because it can provide a composite in which the formation of precipitates is small.

Specifically, in the reduction of copper ions, a strong reducing agent such as hydrazine hydrate, asymmetric dimethylhydrazine, aqueous hydroxylamine solution or sodium borohydride is suitable. These are suitable for the conversion of divalent and monovalent copper compounds to reduced copper due to their ability to reduce the copper compound to zero. The case of producing a composite of an organic compound and a nano copper particle.

The conditions suitable for the reduction reaction differ depending on the type of the copper compound used as the raw material, the type of the reducing agent, the presence or absence of the miscombination, the medium, and the type of the thioether type organic compound. For example, when copper (II) acetate is reduced by sodium borohydride in an aqueous system, zero-valent nano copper particles can be prepared even at a temperature at which the ice bath is cooled. On the other hand, in the case of using hydrazine, the reaction is slow at room temperature, heating to about 60 ° C begins to produce a smooth reduction reaction, when the copper acetate is reduced in the ethylene glycol / water system, at 60 ° C It takes about 2 hours of reaction time. When the reduction reaction is completed in the above manner, a reaction mixture comprising a composite of an organic compound and copper-based nanoparticles can be obtained.

In the reduction of silver ions, specifically, a reducing agent such as dimethylaminoethanol or sodium citrate is preferred. The silver ion can be reduced to a zero valence under relatively mild conditions, and when the silver nitrate is reduced in the aqueous system, the reduction reaction is completed by performing the reaction at 40 ° C for about 2 hours, thereby obtaining an organic compound and a silver-based compound. A reaction mixture of a composite of nanoparticles.

The metal nanoparticles prepared in the above manner are completely removed by the effect of the protective agent, and the water is completely removed to form a dry powder, and even if the solvent is added again, it can be highly dispersed in the same manner as in the state before drying.

Further, if a mixed liquid of nano silver is added to a mixture of a thioether type organic compound, the above medium, and a copper ion compound, and then a reducing agent is added and copper ions are reduced by the above method, The silver surface is covered with copper silver core copper shell nanoparticles.

Further, conversely, if a mixture of thioether-type organic compound, a mixture of the above medium and a silver ion compound is added in advance, and a reducing agent is added and silver ions are reduced by the above method, The surface of the nano copper is covered with silver copper core silver shell nanoparticles.

<Method for Producing Dispersion>

After the reduction reaction, a step of removing the metal compound residue, the reducing reagent residue, the residual polyethylene glycol-containing organic compound, and the like is provided as needed. For the purification of the complex, precipitation, centrifugal precipitation or ultrafiltration may be applied, and the reaction mixture containing the obtained composite may be washed with a washing solvent such as water, ethanol, acetone and the like, and rinsed. Impurities.

<Method of Manufacturing Bonding Material>

As described above, the metal nanoparticle-organic compound composite system is obtained as an aqueous dispersion, but in the final stage of purification, a solvent which is easy to use by adding a material for bonding to the composite is used instead of the solvent for washing. Or, the medium is exchanged, and the suitability as a bonding material is imparted.

Regarding the bonding material, the higher the concentration of the metal contained in the material, the higher the bonding strength can be obtained, but on the other hand, the material needs to be applied by coating, dispenser, mask printing, screen printing, or the like. Since it is supplied to the joint portion, it is necessary to add a solvent or an additive for viscosity adjustment or to adjust the concentration of the metal contained in the material in order to make the characteristics suitable. Therefore, the metal concentration of the aqueous dispersion is adjusted in such a manner that it is suitable for the viscosity range of the printing mode to be the maximum metal concentration. In general, it is preferably about 50 to 95% in terms of ease of supply to the joint portion.

The bonding material of the present invention may be used by adding metal nanoparticles having a particle diameter of about 200 to 1000 nm.

The bonding material of the present invention can also be used by adding a flux component to have a further reducing power.

The bonding material prepared in the above manner is stable in about 1 to 3 months regardless of the preparation concentration as long as it is stored in a closed container.

The level which is practically sufficient in the technical field of the present invention is that the strength of 15 MPa or more can be obtained in the following shear strength test. The bonding material of the present invention exhibits a strength of 15 MPa or more, and preferably exhibits a strength of 20 MPa or more. Again, as The bonding material of the present invention is particularly preferably obtained in an amount of 30 MPa or more.

<Solvent (C) of the present invention>

As the solvent (C) which can be used in the present invention, an alcohol solvent having a boiling point of 150 ° C or higher, an ether solvent having a boiling point of 150 ° C or higher, an ester solvent having a boiling point of 150 ° C or higher, and a boiling point of 150 ° C can be suitably used. The above solvent containing an indoleamine structure.

Here, the alcohol-based solvent having a boiling point of 150 ° C or higher may specifically be a monofunctional alcohol type such as hexanol, heptanol, octanol, decyl alcohol or decyl alcohol; ethylene glycol, propylene glycol, and diethylene glycol; Difunctional alcohols such as alcohol, triethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol; glycerol, butyl triol, glycerol, hexanetriol, heptanetriol, etc. A trifunctional alcohol type; a tetrafunctional alcohol type such as propylene glycol, tetrabutyl alcohol, pentaerythritol, hexanetetraol or heptanediol; and a pentafunctional alcohol type such as pentaerythritol or pentane pentoxide. Further, an alcohol compound having a cyclic structure such as benzenetriol, biphenylpentaol, phenol pentaphenol or cyclohexanol can also be used. In addition to this, a compound having an alcohol group such as citric acid or ascorbic acid can also be used. Further, propylene glycol monomethyl ether, 3-methoxybutanol, propylene glycol n-propyl ether, propylene glycol n-butyl ether, dipropylene glycol methyl ether, diethylene glycol monoethyl ether, or the like, which is an alcohol derivative containing an ether structure, may also be used. Propylene glycol n-propyl ether, dipropylene glycol n-butyl ether, tripropylene glycol methyl ether, tripropylene glycol n-butyl ether and the like.

Here, as the ether solvent having a boiling point of 150 ° C or higher, specifically, polyethylene glycol or polypropylene glycol having a molecular weight of 200 to at most 400 may be mentioned.

Here, as the ester solvent having a boiling point of 150 ° C or higher, specifically, cyclohexyl acetate, dipropylene glycol dimethyl ether, propylene glycol diacetate, dipropylene glycol methyl n-propyl ether, dipropylene glycol A may be mentioned. Ether acetate, 1,4-butanediol diacetate, 1,3-butanediol diacetate, 1,6-hexanediol diacetate, crown ether having a cyclic structure, etc. .

Here, as the solvent containing the internal guanamine structure having a boiling point of 150 ° C or more, specifically, β-endoxime, ε-caprolactam, σ-endoyamine, N-methyl-2 can be mentioned. a pyrrolidone, pyroglutamic acid, piracetam, a β-indoleamine compound such as penicillin or the like.

Among them, an alcohol solvent having a boiling point of 150 ° C or higher and an ether solvent having a boiling point of 150 ° C or higher are preferably used.

More preferably, the difunctional alcohol type such as ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol or heptane has a boiling point of 150 ° C or higher. An alcohol solvent and an ether solvent having a boiling point of 150 ° C or higher.

Among them, ethylene glycol, diethylene glycol, and polyethylene glycol having a molecular weight of 200 to at most 400 are further preferable.

The amount of use can be used as long as it is in the range of 5 to 50% with respect to the metal, and more preferably in the range of 5 to 15%.

<joining>

The bonding material prepared in the above manner can be applied to two copper bars (diameter 10 mm × thickness 5 mm, diameter 3 mm × thickness 2 mm) which are previously washed with dilute hydrochloric acid, and directly heated to make copper or silver nanoparticles. The bonding test piece was prepared by heating the temperature at the temperature of the fusion or heating to a temperature at which the copper or silver nanoparticles were fused. In this case, it can also be carried out under an atmosphere containing hydrogen gas, under a nitrogen atmosphere, or under an atmosphere containing formic acid containing formic acid.

When heating is performed for bonding, the polyethylene glycol site and the metal coordination site which are combined with copper or silver nanoparticles at 200 ° C or lower are decomposed and volatilized.

In the present invention, as the member to be joined (joined material), ceramics, plastics, composite materials thereof and the like may be exemplified in addition to metals (including alloys and intermetallic compounds), but it is particularly preferable in the present invention. Metal (also including alloys and metals joined to each other). Further, the shape and the like of the member are not particularly limited as long as the powder or the paste can be appropriately disposed between the members.

<Measurement of joint strength>

The bonding strength was measured by applying a shear force to the bonded test piece by the method described in JIS Z-03918-5:2002 "Lead-free solder test method". In this specification, Also known as the shear strength test.

[Examples]

Hereinafter, the present invention will be described based on examples. Unless otherwise stated, "%" is the quality standard.

Synthesis Example 1 <Synthesis of copper nanoparticles containing an organic compound (thioether type organic compound (A1) to (A4)) having a polyethylene glycol having a carbon number of 8 to 200 >

To a solution containing copper (II) acetate monohydrate (3.00 g, 15.0 mmol), ethyl 3-(3-(methoxy(polyethoxy)ethoxy)-2-hydroxypropylthio)propanoate [For polyethylene glycol methyl glycidyl ether (polyethylene glycol chain molecular weight 200 (carbon number 8), 1000 (carbon number 46), 2000 (carbon number 91), 3000 (carbon number 136)) 3- An addition compound of methyl mercaptopropionate (the molecular weight of the polyethylene glycol chain is thioether type organic compounds (A1), (A2), (A3), (A4)), respectively, and the following formula] ( 0.451g)

In a mixture of ethylene glycol (10 ml), nitrogen gas was blown at a flow rate of 50 ml/min, and the mixture was heated at 125 ° C for 2 hours, and stirred and degassed. The mixture was returned to room temperature, and a solution obtained by diluting hydrazine hydrate (1.50 g, 30.0 mmol) with 7 ml of water was slowly added dropwise using a syringe pump. About 1/4 amount was slowly added dropwise over 2 hours, and the dropwise addition was temporarily stopped, and after stirring for 2 hours, it was confirmed that the foaming subsidence was completed, and the remaining amount was further added dropwise over 1 hour. The obtained brown solution was heated to 60 ° C and further stirred for 2 hours to complete the reduction reaction.

<Preparation of aqueous dispersion>

Then, the reaction mixture was circulated in a hollow fiber type ultrafiltration membrane module (HIT-1-FUS1582, 145 cm ² , molecular weight 150,000) manufactured by Daicen Membrane Systems, Inc., and added 0.1% equivalent to the filtrate which was exuded. The aqueous hydrate solution was circulated while being purified until the filtrate from the ultrafiltration module became about 500 ml. When the supply of the 0.1% hydrazine hydrate aqueous solution is stopped and concentrated by the ultrafiltration method in this state, copper nanoparticles each having 2.85 g of the thioether type organic compounds (A1) to (A4) are obtained. Aqueous dispersion (a1)~(a4). The non-volatile content of the aqueous dispersions (a1) to (a4) was 16%, and the metal content in the nonvolatiles was 95%.

Further, the thioether type organic compound having a polyethylene glycol chain having a molecular weight of 200 is referred to as a thioether type organic compound (A1), and the molecular weight of 1000 is a thioether type organic compound (A2), and the molecular weight is 2000. The thioether type organic compound (A3) was used, and the thioether type organic compound (A4) was set to have a molecular weight of 3,000. Further, the aqueous dispersion of the copper nanoparticles in which the thioether type organic compounds (A1) to (A4) are combined is referred to as (a1) to (a4), respectively.

Synthesis Example 2 <Synthesis of silver nanoparticles compositing an organic compound (thioether type organic compound (A3)) containing polyethylene glycol having 8 to 200 carbons>

To a mixture containing silver nitrate (I) (2.55 g, 15.0 mmol), thioether type organic compound (A3), 0.451 g, and distilled water (10 ml), a dimethylamine as a reducing agent was added dropwise over 20 minutes using a dropping funnel. After a mixture of ethanol (1.78 g, 20 mmol) and 16.02 g of distilled water, the mixture was heated at 40 ° C for 2 hours to complete the reduction reaction, thereby obtaining a black silver nanoparticle reaction mixture.

<Preparation of aqueous dispersion>

Then, the reaction mixture was circulated in a hollow fiber type ultrafiltration membrane module (HIT-1-FUS1582, 145 cm ² , molecular weight 150,000) manufactured by Daicen Membrane Systems, Inc. until the filtrate from the ultrafiltration unit became about 500 ml. Purification is carried out. When concentrated by the ultrafiltration method in this state, 2.15 g of an aqueous dispersion (b) of a composite of a thioether type organic compound (A3) and silver nanoparticles is obtained. The non-volatile content of the aqueous dispersion (b) was 16%, and the metal content in the non-volatiles was 95%.

Test example 1

5 ml of the above aqueous dispersions (a1) to (a4) were each sealed in a 50 ml three-necked flask, and heated to 40 ° C in a water bath, and nitrogen gas was introduced at a flow rate of 5 ml/min under reduced pressure to completely remove water. And a copper nanoparticle composite dry powder of 1.0 g was obtained. Then, 0.1 g of ethylene glycol which was passed through for 30 minutes was added to the obtained dry powder in a glove bag which was replaced with argon gas, and then mixed with a mortar for 10 minutes to obtain a nonvolatile fraction of 91%. Copper nanoparticle paste.

Using a stainless steel mask having a diameter of 4 mm and a thickness of 150 μm, the obtained copper nanoparticle paste screen was applied onto the copper bar having a diameter of 10 mm and a thickness of 5 mm using a metal spatula. Thereafter, a copper bar having a diameter of 3 mm and a thickness of 2 mm was adhered to the coated surface, and joined under a nitrogen atmosphere at 200 ° C under no pressure. The calcination was carried out at a temperature of 43 ° C/min, and the mixture was kept at each temperature for 10 minutes, and then naturally cooled to obtain a copper rod joint (Example 1 (the aqueous dispersion used was (a1)), and Examples 2 (the aqueous dispersion used was (a2)), Example 3 (the aqueous dispersion used was (a3)), and Example 4 (the aqueous dispersion used was (a4))).

Test example 2

A copper bar-joined body was obtained in the same manner as in Test Example 1 except that the above-mentioned aqueous dispersion (a3) was joined at 300 ° C and 250 ° C (in the following order, Example 5, Example 6) ).

Test Example 3

To the dry powder of the copper nanoparticle composite of the aqueous dispersion (a3), polyethylene glycol (PEG200, PEG300, PEG400) having a molecular weight of 200 to 400 is added in place of ethylene glycol, and the like. A copper nanoparticle paste was obtained in the same manner as in Test Example 1.

In the same manner as in Test Example 1, except that the bonding temperature was 350 ° C, the copper bar material joined body was obtained by using the copper nanoparticle paste as described above. Example 10).

Test Example 4

The same procedure as in Test Example 1 except that N-methyl-2-pyrrolidone or propylene glycol diacetate was added in the dry powder of the copper nanoparticle composite of the above aqueous dispersion (a3) in place of ethylene glycol. In the method, a copper nanoparticle paste was obtained, and as a comparative example, rosinol and dimethylformamide were added to the dry powder of the copper nanoparticle composite of the aqueous dispersion (a3) instead of ethylene glycol. A copper nanoparticle paste was obtained in the same manner as in Test Example 1, except for the above.

The copper bar material joined body was obtained in the same manner as in Example 1 except that the copper nanoparticle paste was used and the bonding temperature was changed to 200° C. (According to Example 11 and Examples) 12. Comparative Example 1 and Comparative Example 2).

Test Example 5

A silver nanoparticle paste was obtained by adjusting the paste in the same manner as in Test Example 1 except that the aqueous dispersion (b) was used instead of the aqueous dispersion (a3).

Then, in the same manner as in Test Example 1, except that the silver nanoparticle paste (b) was used instead of the copper nanoparticle paste (a), respectively, at 350 ° C, 300 ° C, 250 ° C, and 200 ° C. Bonding was carried out to obtain a copper bar joint (Examples 13 to 16).

Evaluation 1

The shear strength test was carried out using the copper bar joints of the above Test Example 1 (Examples 1 to 3). The results are shown in the first table.

Evaluation 2

The shear strength test was carried out using the copper bar joints of the above Test Example 2 (Examples 5 to 6). The results are shown in the second table.

According to the results of the test, a higher shear strength of more than 20 MPa was exhibited under all temperature conditions.

Evaluation 3

The shear strength test was carried out using the copper bar joints of the above Test Example 3 (Examples 7 to 10). The results are shown in Table 3.

According to the results of the test, it is clear that higher shear strength of 20 MPa or more is obtained at a joining temperature of 200 ° C by using not only ethylene glycol but also diethylene glycol and polyethylene glycol having a molecular weight of 200. . On the other hand, in the case of using polyethylene glycol having a molecular weight of 300 or 400, the shear strength of 20 MPa or more is not shown, but the practically sufficient shear strength of 15 MPa or more is exhibited.

Evaluation 4

The shear strength test was carried out using the copper bar joints of the above Test Example 4 (Example 11, Example 12, Comparative Examples 1, 2). The results are shown in Table 4.

The shear strength test was carried out using the copper bar joints of the above Test Example 5 (Examples 13 to 16). The results are shown in Table 5.

[Industrial availability]

The bonding material of the present invention utilizes a joint after the joint to have a melting close to the bulk copper. Point and heat dissipation, and can be suitably used for mounting of semiconductor wafers, bonding in manufacturing steps of LED lighting, bonding in assembly of power devices, etc., particularly devices exposed to high temperatures, devices requiring high reliability at high temperatures Assembly. Further, even if the heating is repeated, the joint portion is not melted again, so that it can be mounted two or three times without being restricted by the reflow temperature, and the installation order can be facilitated.

Claims (7)

A bonding material comprising: a metal nanoparticle (B) compounded with an organic compound (A) having a polyethylene glycol having 8 to 200 carbon atoms, and an alcohol solvent selected from a boiling point of 150 ° C or higher At least one solvent (C) of a group consisting of an ether solvent having a boiling point of 150 ° C or higher, an ester solvent having a boiling point of 150 ° C or higher, and a solvent having an intrinsic amine structure having a boiling point of 150 ° C or higher. The bonding material of claim 1, wherein the organic compound (A) having a polyethylene glycol having a carbon number of 8 to 200 is a compound represented by the following formula (1) and represented by the following formula (2). a compound, a compound represented by the following formula (3), or a (meth) group having a structure represented by the following formula (4) at least one terminal and a polyethylene glycol chain (P) in a side chain; An acrylic polymer (polymer α) and a structure represented by the following formula (4) at least at one terminal and a phosphate residue represented by -OP(O)(OH) ₂ in a side chain ( Compound of methyl)acrylic polymer (polymer β), W-(OCH ₂ CH ₂ ) _n -O-CH ₂ -CH(OH)-CH ₂ -SX (1) [W-(OCH ₂ CH _{2 n} -O-CH ₂ -CH(OH)-CH ₂ -S-] _d Y (2) [W-(OCH ₂ CH ₂ ) _n -O-CH ₂ -CH(OH)-CH ₂ -SR ^a -] _t Z (3) [W in the formulas (1), (2) and (3) is an alkyl group of C ₁ to C ₈ , n is an integer of 4 to 100 representing the number of repetitions, and X is C ₂ ~ C ₁₂ alkyl, allyl, aryl, arylalkyl, -R ¹ -OH, -R ¹ -NHR ² or -R ¹ -(COR ³ ) _m (wherein R ¹ is C ₁ -C saturated hydrocarbon group of _4, R ² is a hydrogen atom, C ₂ ~ C ₄ acyl of, C alkoxycarbonyl group of ₂ ~ C ₄ Or in the aromatic ring may have a C ₁ ~ C ₄ alkyl or the alkoxy group of C ₁ ~ C ₈ of benzyloxycarbonyl group as the substituent group, R ³ is hydroxy, C ₁ ~ C ₄ alkyl group or a C ₁ of ~C ₈ alkoxy, m is an integer from 1 to 3), Y is directly bonded to a sulfur atom, and is a 2 to 4 valent group of a carbon atom, a C ₁ - C ₄ saturated hydrocarbon group or 2 to 3 C ₁ ~ C ₄ saturated hydrocarbon use of -O -, - S-, or -NHR ^b - (R ^b is C ₁ ~ C ₄ saturated hydrocarbon group of) from the connecting group, d is an integer of 2 to 4, R ^a It is a C ₂ -C ₅ alkylcarbonyloxy group, and the Z system is directly bonded to a sulfur atom as a 2 to 6 valent group of a carbon atom, a C ₂ -C ₆ saturated hydrocarbon group, and 2 to 3 C ₂ -C. _{6 A} saturated hydrocarbon group is a group formed by linking -O-, -S- or -NHR ^c - (R ^c is a saturated hydrocarbon group of C ₁ to C ₄ ), or iso-cyanuric acid -N,N',N"- Tri-ethyl, t is an integer of 2 to 6] RS- (4) [In the formula (4), R represents a linear or branched alkyl group having 1 to 18 carbon atoms, or has a hydroxyl group selected from the group consisting of a linear alkoxy group having 1 to 18 carbon atoms, a branched alkoxy group having 1 to 18 carbon atoms, an aralkyloxy group, a substituted phenoxy group, a linear alkylcarbonyl group having 1 to 18 carbon atoms Oxyl group, branched alkylcarbonyloxy group having 1 to 18 carbon atoms, carboxyl group, carboxy group a salt, a linear alkoxycarbonyl group having 1 to 18 carbon atoms, a branched alkoxycarbonyl group having 1 to 18 carbon atoms, a phosphoric acid group, a linear alkyl phosphate group having 1 to 6 carbon atoms, carbon a branched alkyl phosphate group having 1 to 6 atoms, a sulfonic acid group, a linear alkylsulfonic acid group having 1 to 6 carbon atoms, and a branched alkylsulfonic acid group having 1 to 6 carbon atoms A linear or branched alkyl group having 1 to 8 carbon atoms of at least one functional group in the group. The bonding material of claim 1, wherein the organic compound (A) having a polyethylene glycol having a carbon number of 8 to 200 is a compound represented by the following formula (1) and represented by the following formula (2). a compound or a compound represented by the following formula (3), W-(OCH ₂ CH ₂ ) _n -O-CH ₂ -CH(OH)-CH ₂ -SX (1) [W-(OCH ₂ CH ₂ ) _n -O-CH ₂ -CH(OH)-CH ₂ -S-] _d Y (2) [W-(OCH ₂ CH ₂ ) _n -O-CH ₂ -CH(OH)-CH ₂ -SR ^a - ] _t Z (3) [W in the formulas (1), (2) and (3) is an alkyl group of C ₁ to C ₈ , n is an integer of 4 to 100 representing a repeating number, and X is a C ₂ -C ₁₂ alkyl, allyl, aryl, arylalkyl, -R ¹ -OH, -R ¹ -NHR ² , or -R ¹ -(COR ³ ) _m (wherein R ¹ is C ₁ -C _a saturated hydrocarbon group of ₄ , R ² is a hydrogen atom, a C ₂ -C ₄ fluorenyl group, a C ₂ -C ₄ alkoxycarbonyl group, or an C ₁ -C ₄ alkyl group or C ₁ ~ on the aromatic ring. a benzyloxycarbonyl group having a C ₈ alkoxy group as a substituent, R ³ being a hydroxyl group, a C ₁ -C ₄ alkyl group or a C ₁ -C ₈ alkoxy group, m being an integer of 1 to 3), Y system Directly bonded to a sulfur atom is a 2 to 4 valence of a carbon atom, a saturated hydrocarbon group of C ₁ to C ₄ or 2 to 3 C ₁ to C ₄ saturated hydrocarbon groups using -O-, -S- or -NHR ^b -(R ^b a group formed by linking a saturated hydrocarbon group of C ₁ to C ₄ , d is an integer of 2 to 4, R ^a is an alkylcarbonyloxy group of C ₂ to C ₅ , and a Z bond directly bonded to a sulfur atom is carbon. A 2 to 6 valence of an atom, a saturated hydrocarbon group of C ₂ to C ₆ , and 2 to 3 C ₂ -C ₆ saturated hydrocarbon groups using -O-, -S- or -NHR ^c - (R ^c is C ₁ -C _a saturated hydrocarbon group of ₄ ) or a hetero-cyanuric acid-N,N',N"-tri-ethyl group, and t is an integer of 2-6. The bonding material according to claim 1, wherein the solvent (C) is at least one selected from the group consisting of an alcohol solvent having a boiling point of 150 ° C or higher and an ether solvent having a boiling point of 150 ° C or higher. The bonding material according to claim 1, wherein the metal nanoparticle (B) is a silver nanoparticle, a copper nanoparticle, a silver core copper nanoparticle or a copper core silver nanoparticle. The bonding material according to claim 1, wherein the content of the organic compound (A) having a polyethylene glycol having 8 to 200 carbon atoms in the metal nanoparticle is 2 to 15% by mass. The joining material according to any one of claims 1 to 6, wherein the joined object to be joined is a metal or a metal oxide.