JP2020035978A - Method for producing copper particles for bonding, paste for bonding, semiconductor device, and electric / electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To bond copper particles that can be sintered at a low temperature even in a reducing atmosphere, have a uniform sintering rate and a sintering degree between the inside of a bonding layer and a fillet portion, and can obtain copper particles having good bonding characteristics. Provided are a method for producing copper particles, a bonding paste containing copper particles for bonding obtained by the manufacturing method, and a semiconductor device and an electric/electronic component having excellent reliability by using the bonding paste. A copper compound, an amine compound, and a reducing compound are mixed in an organic solvent to obtain a copper particle dispersion, and the copper particle dispersion obtained in the above step is washed with a solvent, A method for producing copper particles for bonding, which comprises a washing step of solid-liquid separating copper particles from a copper particle dispersion liquid, wherein the washing step is carried out in a closed system. [Selection diagram] None

Description

  The present invention relates to a method for manufacturing copper particles for bonding, a bonding paste, a semiconductor device manufactured using the bonding paste, and an electric / electronic component.

The problem of heat generated during the operation of semiconductor products has become remarkable due to the large capacity, high speed processing, and miniaturization of semiconductor products, and so-called thermal management, which dissipates heat from semiconductor products, is becoming an increasingly important issue. It has become to. For this reason, a method of attaching a heat dissipating member such as a heat spreader or a heat sink to a semiconductor product is generally adopted, and a material having a higher thermal conductivity for bonding the heat dissipating member is desired.
On the other hand, depending on the form of the semiconductor product, in order to make the thermal management more efficient, a method of bonding a heat spreader to the die pad portion of the semiconductor device itself or a lead frame to which the semiconductor device is bonded, and exposing the die pad portion to the package surface In this case, a method of giving a function as a heat radiating plate (for example, see Patent Document 1) is adopted.

  Further, the semiconductor element may be bonded to an organic substrate having a heat dissipation mechanism such as a thermal via. Also in this case, the material for bonding the semiconductor element needs to have high thermal conductivity. Further, with the recent increase in luminance of white light emitting LEDs, they have been widely used for lighting devices such as backlighting, ceiling lights, and downlights of full color liquid crystal screens. By the way, when a high current is applied by increasing the output of the light emitting element, there has been a problem that the adhesive bonding the light emitting element and the substrate is discolored by heat, light, or the like, and the electric resistance value changes with time. In particular, in the method of completely relying on the adhesive strength of the adhesive to bond the light emitting element and the substrate, the bonding material loses its adhesive strength at the solder melting temperature at the time of soldering of electronic components and peels off, which is a fatal problem leading to non-lighting. There were concerns. Further, higher performance of the white light emitting LED causes an increase in the amount of heat generated by the light emitting element chip, and accordingly, the structure of the LED and members used therein are required to have improved heat radiation.

  In particular, in recent years, power semiconductor devices using wide band gap semiconductors such as silicon carbide (SiC) and gallium nitride with low power loss have been actively developed, and the heat resistance of the element itself is high, and the temperature is higher than 250 ° C. due to a large current. High temperature operation is possible. However, in order to exhibit such characteristics, it is necessary to efficiently dissipate the heat generated during operation. Therefore, a bonding material having excellent long-term high-temperature heat resistance in addition to conductivity and heat conductivity is required.

  Thus, high thermal conductivity is required for the materials (such as the die attach paste and the material for bonding the heat dissipating member) used for bonding the members of the semiconductor device and the electric / electronic parts. In addition, these materials also need to withstand reflow processing at the same time when the product is mounted on the substrate, and in many cases, a large area of adhesion is required. It is also necessary to have a low stress property for suppressing the stress.

  Here, usually, in order to obtain an adhesive having high thermal conductivity, a metal filler such as silver powder and copper powder and a ceramic filler such as aluminum nitride and boron nitride are used as fillers at a high content in an organic binder. It is necessary to disperse (for example, see Patent Document 2). However, as a result, the elasticity of the cured product is increased, and it is difficult to have both good thermal conductivity and good reflow properties (there is little occurrence of peeling after the reflow treatment).

However, recently, as a candidate for a bonding method that can withstand such a demand, a bonding method using silver nanoparticles that enables bonding at a lower temperature than silver in a bulk body has been attracting attention (for example, Patent Document 3).
By the way, silver particles have very good conductivity, but due to the high price and the problem of migration, replacement with other metals is being studied. Therefore, attention is now focused on copper particles that are inexpensive and have migration resistance as compared with silver particles.

JP 2006-086273 A JP 2005-113059 A JP 2011-240406 A

  However, when bonding with copper nanoparticles requires a high temperature of 300 ° C. for the development of conductivity, and furthermore, the particle size is small, and it is difficult to suppress oxidation, and handling and processing are troublesome. There is. Further, sintering of copper particles requires sintering in a reducing atmosphere from the viewpoint of removing a surface oxide film.

  In addition, although copper nanoparticles for wiring, for which research and development are particularly advanced, can be sintered at a relatively low temperature, when used for bonding, there is a difference in the sintering speed and degree of sintering between the inside of the bonding layer and the fillet. Occurred, and it was difficult to obtain a highly reliable bonded body.

  The present invention has been made in view of such circumstances, is capable of low-temperature sintering even without a reducing atmosphere, has a uniform sintering rate and degree of sintering between the inside of the joining layer and the fillet portion, A method for producing copper particles for bonding capable of obtaining copper particles having good characteristics, a bonding paste containing the copper particles for bonding obtained by the manufacturing method, and excellent reliability by using the bonding paste. It is an object to provide a semiconductor device and an electric / electronic component.

  Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that the problems can be solved by the following invention.

That is, the present disclosure relates to the following.
[1] A step of mixing a copper compound, an amine compound, and a reducing compound in an organic solvent to obtain a copper particle dispersion, and washing the copper particle dispersion obtained in the step with a solvent, A method for producing copper particles for bonding, comprising: a washing step of solid-liquid separating copper particles from a particle dispersion, wherein the cleaning step is performed in a closed system.
[2] The method for producing bonding copper particles according to the above [1], wherein in the washing step, solvent replacement and washing are successively performed.
[3] In the washing step, the copper particle dispersion containing 1 to 50% by mass of the copper particles is supplied to the filtration membrane at a flow rate of 5 to 1500 kg / hr · m ² and a pressure of 0.03 to 1.0 MPa. The method for producing copper particles for bonding according to the above [1] or [2], wherein
[4] The method for producing copper particles for bonding according to any of [1] to [3], wherein the copper particles have an average particle diameter of 1 to 1000 nm.
[5] A bonding paste comprising copper particles for bonding obtained by the production method according to any one of [1] to [4].
[6] A semiconductor device and an electric / electronic component joined using the joining paste according to the above [5].

  According to the present invention, low-temperature sintering is possible even in a reducing atmosphere, sintering speed and degree of sintering between the inside of the joining layer and the fillet portion are uniform, and it is possible to obtain copper particles having good joining characteristics. Provided are a method for producing a joining copper particle, a joining paste containing the joining copper particle obtained by the producing method, and a semiconductor device and an electric / electronic component having excellent reliability by using the joining paste. Can be.

<Method for producing copper particles for joining>
The method for producing copper particles for bonding of the present invention includes a step of mixing a copper compound, an amine compound, and a reducing compound in an organic solvent to obtain a copper particle dispersion, and the copper particles obtained in the step. Washing the dispersion with a solvent, and a washing step of solid-liquid separating the copper particles from the copper particle dispersion, a method for producing copper particles for joining, wherein the washing step is performed in a closed system. .
In the method for producing copper particles for bonding according to the present invention, by performing the washing step in a closed system, oxidation of the surface of the copper particles is suppressed, and copper particles having good bonding characteristics can be obtained.

  Hereinafter, the present invention will be described in detail with reference to an embodiment.

[Step of Obtaining Copper Particle Dispersion]
In this step, a raw material, a copper compound, an amine compound, and a reducing compound are mixed in an organic solvent to obtain a copper particle dispersion.
(Copper compound)
The copper compound used in the present embodiment is not particularly limited as long as it contains a copper atom. Examples of the copper compound include copper carboxylate, copper oxide, copper hydroxide, and copper nitride. Among them, copper carboxylate is preferred from the viewpoint of uniformity during the reaction. These may be used alone or in combination of two or more.

  Copper carboxylate includes copper formate (I), copper acetate (I), copper (I) propionate, copper (I) butyrate, copper (I) valerate, copper (I) caproate, copper (I) caprylate (I) ), Copper (I) caprate, copper (II) formate, copper (II) acetate, copper (II) propionate, copper (II) butyrate, copper (II) valerate, copper (II) caproate, caprylic acid Copper carboxylate anhydrides or hydrates such as copper (II), copper (II) caprate, copper (II) citrate and the like can be mentioned. Among them, copper (II) acetate monohydrate is preferable from the viewpoint of productivity and availability. These may be used alone or in combination of two or more.

  Further, as the copper carboxylate, a commercially available product may be used, or a product obtained by synthesis may be used.

  The synthesis of copper carboxylate can be performed by a known method, for example, it can be obtained by mixing and heating copper (II) hydroxide and a carboxylic acid compound.

Examples of copper oxide include copper (II) oxide and copper (I) oxide, and copper (I) oxide is preferable from the viewpoint of productivity. Examples of copper hydroxide include copper (II) hydroxide and copper (I) hydroxide.
These may be used alone or in combination of two or more.

(Amine compound)
The amine compound used in the present embodiment is not particularly limited as long as it forms a complex with the copper compound.From the viewpoint of sinterability, at least one selected from alkylamines, amino alcohols, alkoxyamines and carboxylic acid amine salts. Compounds containing one kind are preferred, and carboxylic acid amine salts are more preferred.
The amine compound functions as a reaction medium for the decomposition reaction of the copper compound when the copper compound is decomposed by heating the complex of the copper compound and the amine compound. Further, the amine compound has a function of adhering to the surface of copper particles obtained by thermally decomposing the copper compound and suppressing oxidation.

  For this reason, the amine compound used in the present embodiment is appropriately selected from known amine compounds according to the conditions of the thermal decomposition of the complex with the copper compound, the properties expected of the produced copper particles, and the like. be able to.

  Here, the alkylamine is not particularly limited in its structure as long as it is an amine compound having an aliphatic hydrocarbon group such as an alkyl group as a group bonded to an amino group, for example, an alkyl monoamine having one amino group, An alkyl diamine having two amino groups is exemplified. In addition, the said alkyl group may have a substituent further.

Specifically, examples of the alkyl monoamine include dipropylamine, butylamine, dibutylamine, hexylamine, cyclohexylamine, heptylamine, octylamine, nonylamine, decylamine, 3-aminopropyltriethoxysilane, dodecylamine, and oleylamine. As the diamine, ethylenediamine, N, N-dimethylethylenediamine, N, N′-dimethylethylenediamine, N, N-diethylethylenediamine, N, N′-diethylethylenediamine, 1,3-propanediamine, 2,2-dimethyl-1 , 3-propanediamine, N, N-dimethyl-1,3-diaminopropane, N, N′-dimethyl-1,3-diaminopropane, N, N-diethyl-1,3-diaminopropane, 1,4- Diaminobutane, , 5-diamino-2-methylpentane, 1,6-diaminohexane, N, N'-dimethyl-1,6-diaminohexane, 1,7-diamino-heptane, 1,8-diamino octane.
In order to efficiently form a copper carboxylate-amine complex by reacting with the above-mentioned copper carboxylate, the alkyl monoamine is an alkyl such as a primary amine (R ¹ NH ₂ ) or a secondary amine (R ² R ³ NH). Preferably it is a monoamine.
The alkylamine does not include an amino alcohol and an alkoxyamine described below.

  The amino alcohol is not particularly limited in its structure as long as it is an amine compound having a hydroxyl group as a functional group, and examples thereof include an alkanol monoamine having one amino group. Specifically, aminoethanol, heptaminol, isoetalin, propanolamine, sphingosine, 1-amino-2-propanol, 2-aminodibutanol, 2-diethylaminoethanol, 3-diethylamino-1,2-propanediol, 3-dimethyl Amino-1,2-propanediol, 3-methylamino-1,2-propanediol, 3-amino-1,2-propanediol and the like.

The alkoxyamine is not particularly limited in its structure as long as it is an amine compound having an alkoxyl group as a substituent, and examples thereof include an alkoxymonoamine having one amino group and an alkoxydiamine having two amino groups. Can be Specifically, methoxyethylamine, 2-ethoxyethylamine, 3-butoxypropylamine and the like are used as alkoxymonoamines, and N-methoxy-1,3-propanediamine and N-methoxy-1,4- are used as alkoxydiamines. Butanediamine and the like. In addition, in consideration of the coordination force with respect to copper generated by reduction, an alkoxymonoamine such as a primary amine (R ¹ ONH ₂ ) or a secondary amine (R ² (R ³ O) NH) is preferable.

Where the substituents R ¹ of the primary amine that has been described above alkylamines and alkoxyamines represents an alkyl group, it is preferably an alkyl group having 4 to 18 carbon atoms. Further, the substituents R ² and R ³ of the secondary amine represent an alkyl group, and are preferably both an alkyl group having 4 to 18 carbon atoms. The substituents R ² and R ³ may be the same or different. Further, these alkyl groups may have a substituent such as a silyl group and a glycidyl group.

  The carboxylic acid amine salt can be obtained from a carboxylic acid compound and an amine compound, and a commercially available product may be used, or a product obtained in advance by synthesis may be used. Further, the carboxylic acid compound and the amine compound may be separately charged into the reaction vessel during the production process of the copper particles, and may be generated in-situ.

  Carboxylic acid amine salts are formed by blending a carboxylic acid compound and an amine compound in an organic solvent in equivalent amounts of functional groups and mixing them under a relatively mild temperature condition of room temperature (25 ° C.) to about 100 ° C. . It is preferable to take out from the reaction solution containing the product by a distillation method, a recrystallization method, or the like.

  The carboxylic acid compound constituting the carboxylic acid amine salt is not particularly limited as long as it has a carboxy group, and examples thereof include a monocarboxylic acid, a dicarboxylic acid, an aromatic carboxylic acid, and a hydroxy acid. These may be used alone or in combination of two or more. Among them, monocarboxylic acids and dicarboxylic acids are preferred from the viewpoint of reducing the difference in sintering speed between the inside of the bonding layer and the fillet portion.

  The carboxylic acid compound constituting the carboxylic acid amine salt has a thermal decomposition temperature of preferably 200 ° C. or lower, more preferably 190 ° C. or lower, from the viewpoint of reducing the difference in the sintering speed between the inside of the bonding layer and the fillet portion. And more preferably 180 ° C. or lower.

  Further, among the carboxylic acid compounds constituting the carboxylic acid amine salt, those compounds having a boiling point in a region lower than the thermal decomposition temperature have a boiling point from the viewpoint of reducing the difference in sintering speed between the inside of the bonding layer and the fillet portion. It is preferably at most 280 ° C, more preferably at most 260 ° C, even more preferably at most 240 ° C.

  Among the carboxylic acid compounds constituting the carboxylic acid amine salts, monocarboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, octylic acid, nonanoic acid, capric acid, oleic acid, and stearic acid Acids, isostearic acid and the like. These may be used alone or in combination of two or more. Formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, octylic acid, nonanoic acid, and capric acid are preferable, and valeric acid, from the viewpoint of reducing the difference in the sintering rate between the inside of the bonding layer and the fillet portion. , Caproic acid, caprylic acid, nonanoic acid and octylic acid are more preferred.

  Among the carboxylic acid compounds constituting the carboxylic acid amine salt, examples of the dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, diglycolic acid, and the like. No. These may be used alone or in combination of two or more. From the viewpoint of reducing the difference in sintering speed between the inside of the bonding layer and the fillet portion, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, and diglycolic acid are preferable, and oxalic acid, malonic acid, succinic acid, Glycolic acid is more preferred.

Among the carboxylic acid compounds constituting the carboxylic acid amine salt, examples of the aromatic carboxylic acid include benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, and gallic acid. These may be used alone or in combination of two or more.
Benzoic acid is preferred from the viewpoint of reducing the difference in sintering speed between the inside of the bonding layer and the fillet portion.

  Among the carboxylic acid compounds constituting the carboxylic acid amine salt, examples of the hydroxy acid include glycolic acid, lactic acid, tartronic acid, malic acid, glyceric acid, hydroxybutyric acid, tartaric acid, citric acid, and isocitric acid. These may be used alone or in combination of two or more. Glycolic acid, lactic acid, and malic acid are preferred from the viewpoint of reducing the difference in sintering speed between the inside of the bonding layer and the fillet.

  The amine compound constituting the carboxylic acid amine salt is not particularly limited as long as it has a carboxy group, and examples thereof include an alkyl monoamine, an alkyl diamine, and an alkanolamine. These may be used alone or in combination of two or more. From the viewpoint of sinterability, alkyl monoamines and alkanolamines are preferred.

  Among the amine compounds constituting the carboxylic acid amine salt, examples of the alkylmonoamine include methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, dodecylamine and the like. These may be used alone or in combination of two or more. From the viewpoint of sinterability, hexylamine, octylamine and decylamine are preferred.

  Among the amine compounds constituting the carboxylic acid amine salt, examples of the alkyldiamine include 1,1-methanediamine, 1,2-ethanediamine, 1,3-propanediamine, 1,4-butanediamine, and 1,6-hexane. Diamine and 1,8-octanediamine are exemplified. These may be used alone or in combination of two or more. From the viewpoint of sinterability, 1,4-butanediamine and 1,6-hexanediamine are preferred.

  Among the amine compounds constituting the carboxylic acid amine salt, alkanolamines include monoethanolamine, monopropanolamine, monobutanolamine, 2- (2-aminoethylamino) ethanol, and 2- (2-aminoethoxy) ethanol , 1-amino-2-propanol, 2-amino-1-propanol, 3-amino-1,2-propanediol and the like. These may be used alone or in combination of two or more. From the viewpoint of sinterability, monoethanolamine, monopropanolamine, monobutanolamine, 1-amino-2-propanol, and 2-amino-1-propanol are preferred.

  The boiling point of the amino compound is preferably from 70 ° C to 280 ° C, more preferably from 100 ° C to 260 ° C, even more preferably from 120 ° C to 240 ° C. If the boiling point of the amino compound is in the above range, the obtained copper particles show good sinterability. Further, when the boiling point of the amino compound is less than 70 ° C., the amine may volatilize in the heating step, and when it exceeds 280 ° C., it is difficult to remove the copper particles at the time of sintering, and the low-temperature sintering property may not be easily exhibited. Absent. The more preferable boiling point of the amino compound is not lower than the heating temperature in the heating step and not higher than the sintering temperature in use.

(Reducing compound)
The reducing compound used in the present embodiment is not particularly limited as long as it has a reducing power for reducing a copper compound and releasing metallic copper. Further, the reducing compound preferably has a boiling point of 70 ° C. or higher, and more preferably a heating temperature of the heating step or higher. Further, the reducing compound is preferably a compound which is composed of carbon, hydrogen and oxygen and is soluble in an organic solvent described below.

  Such a reducing compound typically includes a hydrazine derivative. Examples of the hydrazine derivative include hydrazine monohydrate, methylhydrazine, ethylhydrazine, n-propylhydrazine, i-propylhydrazine, n-butylhydrazine, i-butylhydrazine, sec-butylhydrazine, t-butylhydrazine, n -Pentylhydrazine, i-pentylhydrazine, neo-pentylhydrazine, t-pentylhydrazine, n-hexylhydrazine, i-hexylhydrazine, n-heptylhydrazine, n-octylhydrazine, n-nonylhydrazine, n-decylhydrazine, n -Undecylhydrazine, n-dodecylhydrazine, cyclohexylhydrazine, phenylhydrazine, 4-methylphenylhydrazine, benzylhydrazine, 2-phenylethylhydrazine, 2-hydrazinoethanol Le, acetoacetate hydrazine and the like. These may be used alone or in combination of two or more.

The method for producing copper particles for bonding according to the present embodiment may further include the following compound.
(Carboxylic acid having 1 to 12 carbon atoms)
The carboxylic acid having 1 to 12 carbon atoms is used for the purpose of controlling the particle size of the obtained copper particles. The carboxylic acid is not particularly limited as long as it has a carboxyl group. For example, monocarboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, octylic acid, nonanoic acid, capric acid, oleic acid, stearic acid, isostearic acid, etc .; oxalic acid, malonic acid Dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, diglycolic acid; aromatics such as benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, and gallic acid Carboxylic acids; examples include hydroxy acids such as glycolic acid, lactic acid, tartronic acid, malic acid, glyceric acid, hydroxybutyric acid, tartaric acid, citric acid, and isocitric acid. From the viewpoint of easy particle size control, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, octylic acid, nonanoic acid, capric acid, oleic acid, stearic acid, isostearic acid, oxalic acid, malon Acids, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and diglycolic acid are preferred.From the viewpoint of sinterability, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid , Caprylic acid, octylic acid, oxalic acid, malonic acid and succinic acid are more preferred, and caproic acid, caprylic acid, octylic acid, oxalic acid and malonic acid are even more preferred.

(Organic solvent)
The organic solvent used in the present embodiment can be used without any particular limitation as long as it can be used as a reaction solvent that does not inhibit the properties of a complex or the like generated from a mixture obtained by mixing the above-described raw materials. . Among them, alcohols having compatibility with the above-mentioned reducing compounds are preferably used.

  Further, since the reduction reaction of copper ions by the reducing compound is an exothermic reaction, it is more preferable that the organic solvent is an organic solvent which does not volatilize during the reduction reaction. When the organic solvent is volatilized, it is difficult to control the generation of copper ions due to decomposition of the copper compound-amine complex and the precipitation of metallic copper due to the reduction of the generated copper ions, and the stability of the particle size may be poor, which is not preferable. . Therefore, the organic solvent preferably has a boiling point of 70 ° C. or higher and is composed of carbon, hydrogen and oxygen.

  Examples of the alcohol used as the organic solvent include 1-propanol, 2-propanol, butanol, pentanol, hexanol, heptanol, octanol, ethylene glycol, 1,3-propanediol, 1,2-propanediol, butyl carbitol, Butyl carbitol acetate, ethyl carbitol, ethyl carbitol acetate, diethylene glycol diethyl ether, butyl cellosolve and the like. These may be used alone or in combination of two or more.

(Formation of the mixture)
First, an organic solvent is accommodated in a reaction vessel, and a copper compound, an amine compound, and a reducing compound, which are the above-described raw material compounds, are mixed in the organic solvent. The order of mixing these compounds is not particularly limited, and the above compounds may be mixed in any order.

  In order to efficiently form a complex between the copper compound and the amine compound, the copper compound and the amine compound are mixed first, mixed at 0 to 110 ° C. for about 5 to 30 minutes, and further reduced. It is preferable to add and mix a reactive compound.

  In the mixing, the amount of each compound used is preferably 0.1 to 10 mol of an amine compound and 0.5 to 5 mol of a reducing compound, more preferably 1 to 10 mol of an amine compound and 1 to 3 mol of a reducing compound, per 1 mol of a copper compound. preferable. At this time, the organic solvent may be used in an amount that allows each component to sufficiently react. For example, about 50 to 2000 mL may be used.

(Heating of the mixture)
Next, the mixture obtained by mixing the above is sufficiently heated to cause the reduction reaction of the copper compound to proceed. By this heating, an unreacted copper compound can be eliminated, and metallic copper can be favorably deposited and grown to form copper particles.

  At this time, the amine compound adheres to the surface of the copper particle and has an action of suppressing the growth of the particle by suppressing the growth.

  The heating temperature in heating the mixture is a temperature at which a copper compound is thermally decomposed and reduced to form copper particles, and is preferably, for example, 70 to 150 ° C, and more preferably 80 to 120 ° C. Further, the heating temperature is preferably lower than the boiling points of the raw material compound and the organic solvent. When the heating temperature is in the above range, copper particles can be efficiently produced, and when a carboxylic acid is used in addition to the amine compound, volatilization of these is suppressed, which is preferable.

  If the heating temperature is lower than 70 ° C., quantitative thermal decomposition of the copper compound is unlikely to occur, and undecomposed copper compound may remain. On the other hand, when the heating temperature is higher than 150 ° C., the volatilization amount of the amine compound becomes too large, and the system becomes non-uniform.

  Thus, a copper particle dispersion can be obtained. In addition, it is preferable that the washing | cleaning solvent mentioned later is added to the obtained copper particle dispersion liquid, and the density | concentration of the copper particle contained in the said copper particle dispersion liquid is adjusted to 1-50 mass%.

[Washing process]
In this step, the copper particle dispersion obtained in the above step is solvent-washed in a closed system, and copper particles are solid-liquid separated from the copper particle dispersion.
In the separation operation such as centrifugation generally used in the production of silver fine particles, the solvent cannot be continuously replaced, and the stirring operation with the cleaning solvent is performed in the atmosphere. According to the findings of the present inventors, the synthesized copper particles are easily oxidized on the surface of the particles, and the oxygen caught in the copper particle dispersion liquid particularly when stirred with a cleaning solvent in the air comes into contact with the synthesized copper particles. As a result, oxidation of the copper particle surface may proceed. On the other hand, in this step, the surface oxidation of the copper particles can be reduced by washing the copper particle dispersion with a solvent in a closed system.

In this step, it is preferable to continuously perform solvent replacement and washing from the viewpoint of reducing surface oxidation of copper particles.
A specific solvent replacement cleaning method is performed under the conditions of a flow rate of 5 to 1500 kg / hr · m ² and a pressure of 0.03 to 1.0 MPa without reslurrying the copper particle dispersion containing 1 to 50% by mass of copper particles. The solvent is supplied to the filtration membrane, and the washing solvent is continuously supplied to the filtration membrane under the above conditions. Thus, the cleaning solvent is supplied to the copper particle dispersion at a flow rate of 5 to 1500 kg / hr · m ² and pressurized at 0.03 to 1.0 MPa to replace the copper particle dispersion with the cleaning agent in a closed system. By doing so, the copper particles can be washed in the absence of oxygen, and the surface oxidation of the copper particles can be reduced.
From such a viewpoint, the flow rate is preferably 10 to 1000 kg / hr · m ² , more preferably 15 to 500 kg / hr · m ² , and still more preferably 20 to 200 kg / hr · m ^2. Is preferably 0.1 to 0.8 MPa, more preferably 0.2 to 0.6 MPa.
The solvent replacement and washing may be further performed after drying under reduced pressure, centrifugation, and the like, which will be described later.

  The washing solvent can be used without any particular limitation as long as it does not damage the protective group of the produced copper particles. Specific examples include water; alcohols such as ethanol and methanol; glycols such as diethylene glycol; and other solvents. The washing solvent is preferably supplied in an amount of 3 to 7 times the volume of the filtration chamber.

The solvent replacement device is not particularly limited as long as the solvent can be sealed and the solvent can be washed. For example, a rotary membrane separation device is preferably used, and a specific example thereof is a horizontal filter plate filter (manufactured by Mitsubishi Kakoki Co., Ltd.).
Copper particles can be obtained by performing, for example, drying under reduced pressure, centrifugal separation, and the like on the solids separated by filtration.

(Shape and size of copper particles)
Copper particles obtained by the method for producing copper particles for bonding of the present embodiment, the copper compound is reduced by the reducing compound in the amine compound, the eluted copper atoms aggregate, nucleation, nucleus growth, the amine compound It is assumed that coated copper particles are formed. Therefore, by appropriately selecting the type of the copper compound, the amine compound, and the reducing compound to be used, and the reaction temperature, the supply rate of the copper atom or the adsorption ability by the amine compound is changed, so that copper particles of any shape and size can be obtained. Obtainable.

  Copper particles obtained by the method for producing copper particles for bonding of the present embodiment can be fired at a low temperature of less than 300 ° C., and a bonding paste using the same can be obtained by sintering the inside of the bonding layer and the fillet portion and There is no difference in the degree of sintering, and a bonding layer with high bonding reliability can be obtained.

The average particle diameter of the copper particles is preferably 1 to 1000 nm, more preferably 20 to 800 nm, and still more preferably 30 to 500 nm, from the viewpoint of the denseness of the bonding layer.
The average particle diameter of the copper particles was determined based on an observation image of a scanning electron microscope (for example, JSM-7600F; SEM, manufactured by JEOL Ltd.). Calculated as the average value of 10). Note that the average value is an arithmetic average value, and 10 or more copper particles may be used in the calculation.

<Joining paste>
The joining paste of the present embodiment includes the joining copper particles obtained by the above-described method for producing the joining copper particles. Therefore, the joining paste of the present embodiment can be joined under no pressure and has excellent adhesiveness, and the sintering speed and the degree of sintering between the inside of the joining layer and the fillet portion are uniform, and the joining property is high. Is suitable as a die attach paste for element bonding or a material for bonding a heat radiating member since a good cured product can be obtained.

  The bonding paste of the present embodiment preferably uses two or more copper particles having different average particle diameters in combination. For example, the average particle diameter of the second copper particles having an average particle diameter larger than that of the first copper particles is preferably about 2 to 10 times the average particle diameter of the first copper particles. Further, the amount of the second copper particles is preferably about 1.5 to 10 times the amount of the first copper particles.

  The bonding paste of the present embodiment preferably contains, in addition to the above-described copper particles, large-diameter copper particles having a larger particle size than the above-described copper particles, a thermosetting resin, an organic solvent, and other additives. Thereby, the influence of the sintering shrinkage of the copper particles can be reduced, and a more reliable bonding layer can be formed.

(Large-sized copper particles)
The large-diameter copper particles preferably have an average particle diameter of more than 1 μm and 30 μm or less, more preferably 2 to 20 μm. The shape is not particularly limited, and spheres, plates, flakes, scales, dendrites, rods, wires, and the like can be used.
The average particle diameter of the large-diameter copper particles can be measured using a laser diffraction / scattering particle size distribution analyzer or the like.

  As the large-sized copper particles, those treated with a lubricant and a rust preventive may be used. A typical example of such a treatment is a treatment with a carboxylic acid compound. Examples of the carboxylic acid compound include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, octylic acid, nonanoic acid, capric acid, palmitic acid, oleic acid, stearic acid, isostearic acid, oxalic acid, Malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, diglycolic acid, benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, gallic acid, glycolic acid, lactic acid, Examples thereof include tartronic acid, malic acid, glyceric acid, hydroxybutyric acid, tartaric acid, citric acid, and isocitrate. From the viewpoint of sinterability with copper particles, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, octylic acid, nonanoic acid, capric acid, palmitic acid, oleic acid, stearic acid, isostearic acid, Oxalic acid, malonic acid, succinic acid, and glutaric acid are preferred, and from the viewpoint of the dispersibility and oxidation resistance of the copper particles, caproic acid, caprylic acid, octylic acid, nonanoic acid, capric acid, malonic acid, succinic acid, and glutaric acid are used. Is more preferred.

(Thermosetting resin)
The thermosetting resin can be used without particular limitation as long as it is a thermosetting resin generally used as an adhesive. Among them, a liquid resin is preferable, and a resin that is liquid at room temperature (25 ° C.) is more preferable. Examples of the thermosetting resin include a cyanate resin, an epoxy resin, a radically polymerizable acrylic resin, and a maleimide resin. These may be used alone or in combination of two or more.
When the bonding paste of the present embodiment contains a thermosetting resin, an adhesive material (paste) having an appropriate viscosity can be obtained. Further, it is preferable that the bonding paste of the present embodiment contains a thermosetting resin, because the temperature of the bonding paste rises due to the reaction heat at the time of curing and has an effect of promoting the sinterability of the copper particles.

  The cyanate resin is a compound having a —NCO group in a molecule, and is a resin that forms a three-dimensional network structure and is cured by a reaction of the —NCO group by heating. Specific examples include 1,3-dicyanatobenzene, 1,4-dicyanatobenzene, 1,3,5-tricyanatobenzene, 1,3-dicyanatonaphthalene, 1,4-dicyanatonaphthalene, 6-dicyanatonaphthalene, 1,8-dicyanatonaphthalene, 2,6-dicyanatonaphthalene, 2,7-dicyanatonaphthalene, 1,3,6-tricyanatonaphthalene, 4,4′-dicyanatobiphenyl, bis (4-cyanatophenyl) methane, bis (3,5-dimethyl-4-cyanatophenyl) methane, 2,2-bis (4-cyanatophenyl) propane, 2,2-bis (3,5-dibromo -4-cyanatophenyl) propane, bis (4-cyanatophenyl) ether, bis (4-cyanatophenyl) thioether, bis (4-cyanatophenyl) Sulfone, tris (4-cyanatophenyl) phosphite, tris (4-cyanatophenyl) phosphate, and the like cyanates obtained by a reaction between novolak resin and a cyanogen halide. Further, a prepolymer having a triazine ring formed by trimerizing a cyanate group of these polyfunctional cyanate resins can also be used. The prepolymer is obtained by polymerizing the above polyfunctional cyanate resin monomer with, for example, a mineral acid, an acid such as a Lewis acid, a base such as sodium alcoholate, a tertiary amine, or a salt such as sodium carbonate as a catalyst. can get.

  As the curing accelerator for the cyanate resin, generally known curing accelerators can be used. For example, organometallic complexes such as zinc octylate, tin octylate, cobalt naphthenate, zinc naphthenate, and iron acetylacetone; metal salts such as aluminum chloride, tin chloride and zinc chloride; and amines such as triethylamine and dimethylbenzylamine. However, the present invention is not limited to these. These curing accelerators can be used alone or in combination of two or more.

  The epoxy resin is a compound having one or more glycidyl groups in the molecule, and is a resin that forms a three-dimensional network structure by the reaction of the glycidyl groups by heating and is cured. It is preferable that two or more glycidyl groups are contained in one molecule, because a single compound having only one glycidyl group cannot exhibit sufficient cured product properties. A compound containing two or more glycidyl groups in one molecule can be obtained by epoxidizing a compound having two or more hydroxyl groups. Examples of such compounds include bisphenol compounds such as bisphenol A, bisphenol F, and biphenol or derivatives thereof, and alicyclic rings such as hydrogenated bisphenol A, hydrogenated bisphenol F, hydrogenated biphenol, cyclohexanediol, cyclohexanedimethanol, and cyclohexanediethanol. Bifunctional ones obtained by epoxidizing aliphatic diols such as diols having a structure or derivatives thereof, aliphatic diols such as butanediol, hexanediol, octanediol, nonanediol, and decanediol; trihydroxyphenylmethane skeleton; aminophenol Trifunctional compounds obtained by epoxidizing compounds having a skeleton, phenol novolak resin, cresol novolak resin, phenol aralkyl resin, biphenyl Aralkyl resins, and the naphthol aralkyl resin as polyfunctional epoxidized include, without limitation thereto. Moreover, since the said epoxy resin becomes paste form at room temperature (25 degreeC) as joining paste, what is liquid at room temperature (25 degreeC) alone or as a mixture is preferable. It is also possible to use reactive diluents as usual. Examples of the reactive diluent include monofunctional aromatic glycidyl ethers such as phenyl glycidyl ether and cresyl glycidyl ether, and aliphatic glycidyl ethers.

  At this time, a curing agent is used for the purpose of curing the epoxy resin. Examples of the curing agent for the epoxy resin include an aliphatic amine, an aromatic amine, dicyandiamide, a dihydrazide compound, an acid anhydride, and a phenol resin. . Examples of the dihydrazide compound include carboxylic acid dihydrazide such as adipic acid dihydrazide, dodecanoic acid dihydrazide, isophthalic acid dihydrazide, p-oxybenzoic acid dihydrazide, and the like.Examples of acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, Examples include phthalic anhydride, endomethylenetetrahydrophthalic anhydride, dodecenylsuccinic anhydride, a reaction product of maleic anhydride and polybutadiene, and a copolymer of maleic anhydride and styrene.

Further, a curing accelerator can be blended to promote curing.Examples of curing accelerators for epoxy resins include imidazoles, triphenylphosphine or tetraphenylphosphine and salts thereof, amine compounds such as diazabicycloundecene, and the like. And salts thereof. For example, 2-methylimidazole, 2-ethylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethyl imidazole, _2-C 11 _{H 23} -, imidazole compounds such as the adduct of 2-methylimidazole and 2,4-diamino-6-vinyl-triazine is preferably used. Among them, particularly preferred are imidazole compounds having a melting point of 180 ° C. or higher.

  The radically polymerizable acrylic resin is a compound having a (meth) acryloyl group in a molecule, and is a resin which forms a three-dimensional network structure by the reaction of the (meth) acryloyl group and is cured. It is preferable that one or more (meth) acryloyl groups are contained in the molecule.

  Here, as the acrylic resin, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (Meth) acrylate, 4-hydroxybutyl (meth) acrylate, 1,2-cyclohexanediol mono (meth) acrylate, 1,3-cyclohexanediol mono (meth) acrylate, 1,4-cyclohexanediol mono (meth) acrylate, 1,2-cyclohexane dimethanol mono (meth) acrylate, 1,3-cyclohexane dimethanol mono (meth) acrylate, 1,4-cyclohexane dimethanol mono (meth) acrylate, 1,2-cyclohexane di Tanol mono (meth) acrylate, 1,3-cyclohexanediethanol mono (meth) acrylate, 1,4-cyclohexanediethanol mono (meth) acrylate, glycerin mono (meth) acrylate, glycerin di (meth) acrylate, trimethylolpropane mono ( Has a hydroxyl group such as meth) acrylate, trimethylolpropane di (meth) acrylate, pentaerythritol mono (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, neopentyl glycol mono (meth) acrylate, etc. (Meth) acrylates and (meth) acrylates having carboxyl groups obtained by reacting these (meth) acrylates having hydroxyl groups with dicarboxylic acids or derivatives thereof Acrylate and the like. Examples of dicarboxylic acids that can be used here include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, phthalic acid, and tetrahydrophthalic acid. , Hexahydrophthalic acid and derivatives thereof.

  Further, as particularly preferred acrylic resins, polyethers, polyesters, polycarbonates, compounds having a (meth) acryl group in poly (meth) acrylate having a molecular weight of 100 to 10,000, (meth) acrylate having a hydroxyl group, and having a hydroxyl group (Meth) acrylamide and the like.

  The maleimide resin is a compound containing one or more maleimide groups in one molecule, and is a resin that forms a three-dimensional network structure and is cured by a reaction of the maleimide groups by heating. For example, N, N '-(4,4'-diphenylmethane) bismaleimide, bis (3-ethyl-5-methyl-4-maleimidophenyl) methane, 2,2-bis [4- (4-maleimidophenoxy) phenyl ] Bismaleimide resins such as propane. More preferred maleimide resins are compounds obtained by the reaction of a dimer acid diamine and maleic anhydride, and compounds obtained by the reaction of a maleimidated amino acid such as maleimide acetic acid and maleimidocaproic acid with a polyol. The maleimidated amino acid is obtained by reacting maleic anhydride with aminoacetic acid or aminocaproic acid, and the polyol is preferably a polyether polyol, a polyester polyol, a polycarbonate polyol, or a poly (meth) acrylate polyol. Those not containing are particularly preferred.

  Here, when the thermosetting resin is blended, it is blended so as to be 1 to 20 parts by mass when the total amount of the copper particles and the large-diameter copper particles is 100 parts by mass. When the content of the thermosetting resin is 1 part by mass or more, the adhesive effect by the thermosetting resin can be sufficiently obtained, and when the content of the thermosetting resin is 20 parts by mass or less, the decrease in the proportion of the copper component is suppressed. In addition, high heat conductivity can be sufficiently ensured, and heat dissipation can be improved. In addition, the organic component is not excessively increased, and deterioration due to light and heat is suppressed, and as a result, the life of the light emitting device can be increased. By using such a blending range, contact between the copper particles and / or large-diameter copper particles is prevented by utilizing the adhesive performance of the thermosetting resin, and the mechanical strength of the entire adhesive layer is maintained. Can be easily done.

(Organic solvent)
As the organic solvent, a known solvent can be used as long as it functions as a reducing agent.
Alcohol is preferable as the organic solvent, and examples thereof include aliphatic polyhydric alcohols. Examples of the aliphatic polyhydric alcohol include glycols such as ethylene glycol, diethylene glycol, propylene glycol, diprovylene glycol, 1,4-butanediol, glycerin, and polyethylene glycol. These organic solvents may be used alone or in combination of two or more.

  By using alcohol as an organic solvent, the heat treatment at the time of paste curing (sintering) raises the temperature to increase the alcohol's reducing power, and the copper oxide partially present in the copper particles and on the metal substrate It is considered that a metal oxide (for example, copper oxide) is reduced by an alcohol to become a pure metal, and as a result, a cured film having higher density, higher conductivity, and higher adhesion to a substrate can be formed. In addition, the alcohol is partially refluxed during the heat treatment when the paste is cured by being sandwiched between the semiconductor element and the metal substrate, so that the alcohol, which is a solvent, is not immediately lost from the system due to volatilization, and the paste having a boiling point or higher is removed. At the curing temperature, the metal oxide becomes more efficiently reduced.

  The boiling point of the organic solvent is specifically 100 to 300 ° C, preferably 150 to 290 ° C. When the boiling point is 100 ° C. or higher, the volatility does not become too high even at room temperature, and a reduction in the reduction ability due to the volatilization of the dispersion medium can be suppressed, and a stable adhesive strength can be obtained. Further, when the boiling point is 300 ° C. or less, sintering of the cured film (conductive film) is likely to occur, and a film having excellent denseness can be formed. Further, it is possible to suppress the organic solvent from remaining in the film without being volatilized.

  When the organic solvent is compounded, the compounding amount is preferably 7 to 20 parts by mass when the copper particles are 100 parts by mass. When the amount is 7 parts by mass or more, the viscosity does not become too high, and the workability can be improved. When the amount is 20 parts by mass or less, the decrease in the viscosity is suppressed, the precipitation of copper in the paste is suppressed, and the reliability is increased. be able to.

  In the bonding paste of the present embodiment, in addition to the above-described components, as long as the effects of the present invention are not impaired, a curing accelerator, rubber, silicone, etc., which are generally blended with this type of composition, reduce stress. Agents, coupling agents, defoamers, surfactants, colorants (pigments, dyes), various polymerization inhibitors, antioxidants, solvents, and other various additives can be added as necessary. Each of these additives may be used alone or in combination of two or more.

  The bonding paste of the present embodiment is obtained by sufficiently mixing the above-described copper particles, and, if necessary, additives such as large-diameter copper particles, a thermosetting resin, an organic solvent, and a coupling agent. Further, it can be prepared by performing a kneading treatment with a disperser, a kneader, a three-roll mill or the like, and then defoaming.

The viscosity of the bonding paste of the present embodiment is, for example, preferably from 20 to 300 Pa · s, and more preferably from 40 to 200 Pa · s.
The bonding strength of the bonding paste of the present embodiment is preferably 25 MPa or more, more preferably 30 MPa or more.
The viscosity and the bonding strength can be measured by the methods described in Examples.

  The bonding paste of the present embodiment obtained in this manner is excellent in high thermal conductivity and heat dissipation. Therefore, when used as a bonding material for an element or a heat radiating member to a substrate or the like, the heat dissipation inside the device to the outside can be improved, and the product characteristics can be stabilized.

<Semiconductor devices and electrical / electronic components>
Since the semiconductor device and the electric / electronic component of the present embodiment are joined using the above-mentioned joining paste, they have excellent reliability.

  The semiconductor device of this embodiment is one in which a semiconductor element is adhered to a substrate serving as an element supporting member using the above-mentioned bonding paste. That is, the bonding paste is used here as a die attach paste, and the semiconductor element and the substrate are bonded and fixed via the paste.

Here, the semiconductor element may be any known semiconductor element, and examples include a transistor and a diode. Furthermore, as this semiconductor element, a light emitting element such as an LED is cited. The type of the light-emitting element is not particularly limited, and examples thereof include a light-emitting element in which a nitride semiconductor such as InN, AlN, GaN, InGaN, AlGaN, and InGaAlN is formed as a light-emitting layer on a substrate by MOBVC or the like. Can be
Examples of the element supporting member include a supporting member formed of a material such as copper, copper-plated copper, PPF (pre-plating lead frame), glass epoxy, and ceramics.

  By using the bonding paste of this embodiment, a base material that has not been subjected to metal plating can be bonded. In the semiconductor device obtained in this way, the connection reliability with respect to the temperature cycle after mounting is dramatically improved as compared with the related art. Further, since the electric resistance value is sufficiently small and the change with time is small, there is an advantage that the output does not decrease with time even when driven for a long time and the life is long.

  Further, the electric / electronic component of the present embodiment is obtained by bonding a heat radiating member to a heat generating member using the above-mentioned bonding paste. That is, the bonding paste is used as a material for bonding the heat radiating member, and the heat radiating member and the heat generating member are bonded and fixed via the bonding paste.

  The heat generating member may be the above-described semiconductor element or a member having the semiconductor element, or may be another heat generating member. Examples of the heat generating member other than the semiconductor element include an optical pickup and a power transistor. In addition, examples of the heat radiating member include a heat sink and a heat spreader.

  In this manner, by bonding the heat radiating member to the heat generating member by using the above-described bonding paste, the heat generated by the heat generating member can be efficiently released to the outside by the heat radiating member, and the temperature rise of the heat generating member can be reduced. Can be suppressed. The heat-generating member and the heat-dissipating member may be directly bonded via a bonding paste, or may be indirectly bonded with another member having high thermal conductivity interposed therebetween.

  Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

(Preparation of carboxylic acid amine salt)
[Preparation Example 1]
40 mmol of nonanoic acid (manufactured by Tokyo Chemical Industry Co., Ltd., trade name: nonanoic acid) and 40 mmol of hexylamine (manufactured by Tokyo Chemical Industry Co., Ltd., trade name: hexylamine) are placed in a 50 mL sample bottle, and an aluminum block type is used. When the mixture was stirred and mixed in a heating stirrer, heat was generated up to 60 ° C. Subsequently, the mixture was stirred and mixed at 60 ° C. for 15 minutes, and cooled to room temperature (25 ° C.) to obtain hexylamine nonanoate (10.3 g, yield 99.2%).

(Production of copper particles)
[Synthesis Example 1]
Copper acetate (II) monohydrate (manufactured by Tokyo Chemical Industry Co., Ltd., trade name: copper acetate) in a 2000 mL four-neck separable flask equipped with a nitrogen inlet tube, thermocouple, Dimroth, and dropping funnel 4 mol of (II) monohydrate), 40 mmol of hexylamine nonanoate obtained in Preparation Example 1 as an amine compound, and 600 mL of butyl cellosolve (manufactured by Tokyo Chemical Industry Co., Ltd.) as an organic solvent were added at 90 ° C. for 5 minutes. The mixture was mixed to obtain a copper precursor solution. After cooling the copper precursor solution to room temperature (25 ° C.), hydrazine monohydrate (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd., trade name: hydrazine monohydrate) was added to 500 mL of 1-propanol as a reducing compound. 3) A solution in which 3 mol was dissolved was added dropwise to the copper precursor solution, and the mixture was stirred for 30 minutes. The temperature was raised again to 90 ° C., and the mixture was heated and stirred for 2 hours, and then cooled to room temperature (25 ° C.) to obtain a copper particle dispersion containing 2% by mass of copper particles.

The above-mentioned copper particle dispersion is supplied to a sealed filtration membrane of DyF152 / s (trade name, horizontal filter plate type filter, manufactured by Mitsubishi Kakoki Co., Ltd.) at a flow rate of 20 kg / hr · m ² and a pressure of 0.1 MPa, Further, 1000 mL of ethanol was continuously supplied to obtain a copper particle concentrated solution in which solvent was replaced with ethanol. In a DyF152 / s, 1000 mL of diethylene glycol (manufactured by Tokyo Kasei Kogyo Co., Ltd.) was continuously supplied from the copper particle concentrated solution with the solvent replaced with ethanol, and the solvent was replaced with diethylene glycol, followed by centrifugation (4000 rpm). A copper particle concentrate having an average particle diameter of 50 nm was obtained.
The average particle diameter of the obtained copper particles was determined by centrifuging the obtained copper particle concentrate (4000 rpm (1 minute)) to obtain a solid substance, drying the centrifuged solid substance under reduced pressure, and scanning. It was calculated as an average value of 10 arbitrarily selected copper particles (n = 10) based on an observation image of an electron microscope (trade name: JSM-7600F; SEM, manufactured by JEOL Ltd.).

(Example 1)
100 parts by mass of the copper particles obtained in Synthesis Example 1 and 15 parts by mass of diethylene glycol (produced by Tokyo Chemical Industry Co., Ltd.) as an organic solvent were prepared and kneaded with a roll to obtain a bonding paste. The obtained joining paste was evaluated by the following method. The results are shown in Table 1.

<Evaluation method of bonding paste>
[viscosity]
The value was measured at 25 ° C. and 5 rpm using an E-type viscometer (3 ° cone).

[Pot life]
The number of days until the viscosity when the bonding paste was allowed to stand in a constant temperature bath at 25 ° C. increased to 0.7 times or more the initial viscosity was measured.

[Electric resistance]
The joining paste was applied to a glass substrate (1 mm in thickness) by screen printing so as to have a thickness of 25 μm, and was cured at 200 ° C. for 60 minutes. The electrical resistance of the obtained sintered film was measured by a four-point needle method using Loresta GP (trade name, manufactured by Mitsubishi Chemical Analytic).

<Semiconductor device evaluation method>
[Joint strength]
A silicon chip having a gold deposition layer provided on a bonding surface of 2 mm × 2 mm was mounted on a pure copper frame and a PPF (Ni-Pd / Au-plated copper frame) using a bonding paste, and nitrogen (3% hydrogen) was used. The composition was cured at 200 ° C. for 60 minutes in an atmosphere. After the curing and after the moisture absorption treatment (85 ° C., relative humidity 85%, 72 hours), the die shear strength at room temperature (25 ° C.) was measured for each using DAGE 4000Plus (product name, manufactured by Nordson Corporation).

[Cold and thermal shock resistance]
A silicon chip provided with a gold vapor-deposited layer on a bonding surface of 2 mm × 2 mm was mounted on a copper frame and a PPF using a bonding paste, and cured at 200 ° C. for 60 minutes in a nitrogen (3% hydrogen) atmosphere. Using an epoxy sealing material (trade name: KE-G3000D) manufactured by Kyocera Corporation, the package molded under the following conditions was subjected to a moisture absorption treatment at 85 ° C. and a relative humidity of 85% for 168 hours, and then an IR reflow treatment ( 260 ° C., 10 seconds) and a cooling / heating cycle process (the operation of raising the temperature from −55 ° C. to 150 ° C. and cooling to −55 ° C. is one cycle, and this is 1000 cycles). The number of internal cracks was observed with an ultrasonic microscope.
Table 1 shows the number of cracked samples for the five samples.

(Molding condition)
Package: 80pQFP (14mm x 20mm x 2mm thickness)
Chip: Backside gold-plated silicon chip Lead frame: PPF and copper Molding of sealing material: 175 ° C, 2 minutes Post-mold cure: 175 ° C, 8 hours

From the above results, the bonding paste containing the copper particles obtained by the method for manufacturing the bonding copper particles of the present invention, in which the washing step is performed in a closed system, has a high sinterability in both the coating film state and the bonding state. .
In addition, it was found that a bonding paste containing copper particles obtained by the method for producing copper particles for bonding of the present invention has high bonding reliability. Therefore, by using the bonding paste, a semiconductor device and an electric / electronic device having excellent reliability can be obtained.

Claims (6)

A step of mixing a copper compound, an amine compound, and a reducing compound in an organic solvent to obtain a copper particle dispersion, and washing the copper particle dispersion obtained in the step with a solvent, and washing the copper particle dispersion. A method for producing copper particles for joining, comprising a washing step of solid-liquid separation of copper particles from,
A method for producing copper particles for bonding, wherein the washing step is performed in a closed system.   The method for producing copper particles for bonding according to claim 1, wherein in the cleaning step, solvent replacement and cleaning are performed continuously. In the washing step, the copper particle dispersion containing 1 to 50% by mass of the copper particles is supplied to a filtration membrane at a flow rate of 5 to 1500 kg / hr · m ² and a pressure of 0.03 to 1.0 MPa. The method for producing copper particles for joining according to claim 1.   The method for producing copper particles for bonding according to any one of claims 1 to 3, wherein the copper particles have an average particle diameter of 1 to 1000 nm.   A bonding paste, comprising a bonding copper particle obtained by the production method according to claim 1.   A semiconductor device and an electric / electronic component joined using the joining paste according to claim 5.