JP2008013466A - Copper formate complex, method for producing copper particle and method for producing circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for simply and inexpensively producing copper particles and a method for producing a circuit board by using a liquid material dispersing the copper particles and to provide a copper formate complex for producing the copper particles. <P>SOLUTION: The invention relates to the method for producing copper particles by decomposing the copper formate complex represented by general formula (1), (in the formula, Cu is a divalent copper, R<SP>1</SP>and R<SP>2</SP>are each a (substituted) aliphatic hydrocarbon group), in a way in which the divalent copper is reduced to zero-valent copper, and the formic acid ligand is oxidized into carbon dioxide. The invention also relates to the method for producing the circuit board by coating the liquid material dispersing the copper particles onto a substrate and the invention relates to the copper formate complex represented by general formula (1). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a copper formate complex, a method for producing copper particles, and a method for producing a wiring board.

  Many of the electronic devices that are the foundation of the modern industry are manufactured on the basis of using an apparatus installed in a clean room, performing film formation in a vacuum process, and performing patterning by photolithography. The core of the technology is semiconductor and flat panel display manufacturing technology, and the problems of the high-impact device industry, such as very expensive devices and enormous resources and energy consumption, are becoming obvious. Therefore, the emergence of an ultra-low energy process industry that changes such an industrial structure is desired. As an alternative technique, a device fabrication method that does not use vacuum, clean room, or photolithography is expected.

  As such an ultra-low energy process, a highly efficient device manufacturing process currently called “micro liquid process” has attracted attention. In the micro liquid process, a functional liquid material is pattern-applied only to a necessary portion to obtain a thin film pattern. In addition to the fact that the process is very simple, the material utilization efficiency is close to 100% and can be considered as an ideal process.

  For example, a metal ink containing metal nanoparticles as a functional liquid material is applied by patterning to wiring (ribs, spacers, etc.), gates, sources, and drains in the device structure by an inkjet method. Thereafter, device wiring (ribs, spacers) and device key conductive elements (gates, sources, drains) can be formed by a drying and firing process.

By the way, in recent years, the use of functional liquid materials containing such metal nanoparticles has attracted attention. For example, a low noise amplifier in which a conductive paste containing silver fine particles is applied has been studied (for example, Patent Document 1).
It has also been reported that hexadecylamine and [Cu (OCH (Me) CH ₂ NMe ₂ ) ₂ ] complex are mixed to obtain copper nanoparticles whose surface is modified with hexadecylamine (for example, non-patent literature). 1).

However, silver fine particles have a problem in cost, and copper nanoparticles have a problem that it is difficult to synthesize a copper complex as a starting material. In addition, since hexadecylamine is not an ink medium, it is necessary to isolate, redisperse, concentrate, and filter nanoparticles from hexadecylamine in order to make an ink. There's a problem.
On the other hand, a method for obtaining a copper formate complex useful as a precursor for laminating metallic copper from anhydrous copper formate and a substituted pyridine derivative is known. However, copper fine particles have not been prepared from the complex yet (for example, Patent Document 2).

JP 2004-304649 A US 6770122 Langmuir, 2004, 20, 9453-9455

  An object of the present invention is to provide a method for producing copper particles, a method for producing a wiring board using a liquid material in which the copper particles are dispersed, and formic acid used for producing the copper particles, simply and at low cost. It is to provide a copper complex.

（式中、Ｃｕは２価の銅、Ｒ^１およびＲ^２はそれぞれ置換基を有していてもよい脂肪族炭化水素基を示す。）
で表されることを特徴とする。
これにより、銅粒子の修飾剤として優れている脂肪族アミンが銅に配位しているため、銅粒子の製造に好ましく用いられるギ酸銅錯体を得ることができる。 Such an object is achieved by the present invention described below.
The copper formate complex of the present invention has the following general formula (1):

(In the formula, Cu represents divalent copper, and R ¹ and R ² each represents an aliphatic hydrocarbon group which may have a substituent.)
It is represented by.
Thereby, since the aliphatic amine excellent as a modifier of copper particles is coordinated to copper, the copper formate complex preferably used for manufacture of a copper particle can be obtained.

In the copper formate complex of the present invention, it is preferable that R ¹ and R ² in the general formula (1) each have 4 to 20 carbon atoms.
Thereby, since carbon number of an aliphatic amine ligand is 4-20 comparatively long, a stable copper formate complex can be obtained. Moreover, by decomposing the copper formate complex, copper particles having a stable and uniform particle size in which the aliphatic amine is modified to copper can be produced.

In the copper formate complex of the present invention, each of —NH ₂ R ¹ and —NH ₂ R ² in the general formula (1) is preferably a primary amine ligand.
Thereby, since the steric hindrance between amine ligands can be prevented or reduced, a stable copper formate complex can be obtained. Moreover, stable copper particles can be produced by decomposing the copper formate complex.

In the copper formate complex of the present invention, the aliphatic hydrocarbon group is preferably an alkyl group.
Thereby, since the copper formate complex does not have an unsaturated bond, a stable copper formate complex can be obtained without causing side reactions. Moreover, stable copper particles can be produced by decomposing the copper formate complex.

（式中、Ｃｕは２価の銅、Ｒ^１およびＲ^２はそれぞれ置換基を有していてもよい脂肪族炭化水素基を示す。）
で表されるギ酸銅錯体の前記２価の銅が０価の銅に還元されるとともに、前記ギ酸配位子が二酸化炭素に酸化されるように前記ギ酸銅錯体を分解することにより銅粒子を得ることを特徴とする。
これにより、ギ酸銅錯体を分解するのみで銅粒子を得ることができるため、簡便かつ迅速に銅粒子を収率よく製造することができる。 The manufacturing method of the copper particle of this invention is the following general formula (1).

(In the formula, Cu represents divalent copper, and R ¹ and R ² each represents an aliphatic hydrocarbon group which may have a substituent.)
The divalent copper of the copper formate complex represented by the formula is reduced to zero valent copper, and the copper formate complex is decomposed so that the formic acid ligand is oxidized to carbon dioxide. It is characterized by obtaining.
Thereby, since a copper particle can be obtained only by decomposing | disassembling a copper formate complex, a copper particle can be manufactured easily and rapidly with a sufficient yield.

（式中、Ｃｕは２価の銅、Ｒ^１およびＲ^２はそれぞれ置換基を有していてもよい脂肪族炭化水素基を示す。）
で表されるギ酸銅錯体を得る第１の工程と、
前記ギ酸銅錯体の前記２価の銅が０価の銅に還元されるとともに、前記ギ酸配位子が二酸化炭素に酸化されるように前記ギ酸銅錯体を分解することにより銅粒子を得る第２の工程とを有することを特徴とする。
これにより、安価な材料を用いているため、低コストで銅粒子を得ることができる。また、第１の工程に引き続いて第２の工程を行うため、極めて簡便かつ迅速に収率よく銅粒子を得ることができる。 In the method for producing copper particles of the present invention, unmodified copper formate is dissolved in an aliphatic amine to obtain the following general formula (1).

(In the formula, Cu represents divalent copper, and R ¹ and R ² each represents an aliphatic hydrocarbon group which may have a substituent.)
A first step of obtaining a copper formate complex represented by:
Second, obtaining the copper particles by decomposing the copper formate complex so that the divalent copper of the copper formate complex is reduced to zero-valent copper and the formic acid ligand is oxidized to carbon dioxide. It has the process of this.
Thereby, since an inexpensive material is used, copper particles can be obtained at low cost. In addition, since the second step is performed subsequent to the first step, copper particles can be obtained very simply and quickly with a high yield.

In the method for producing copper particles of the present invention, the unmodified copper formate is preferably dissolved by heating.
Thereby, since an aliphatic amine melt | dissolves reliably, a copper particle can be obtained efficiently.
In the method for producing copper particles of the present invention, the aliphatic amine is preferably a saturated aliphatic amine having 4 to 20 carbon atoms.
Thereby, since an aliphatic amine ligand is a C4-C20 saturated thing, it does not raise | generate a side reaction, The stable copper particle of the uniform particle size which does not aggregate can be obtained.

In the method for producing copper particles of the present invention, the decomposition of the copper formate complex is preferably performed by heating to near the decomposition temperature of the copper formate complex or higher than the decomposition temperature.
Thereby, since a copper formate complex is decomposed | disassembled reliably, a copper particle can be obtained reliably.
In the method for producing copper particles of the present invention, the heating temperature of the copper formate complex is preferably 70 to 200 ° C.
Thereby, since a copper formate complex is decomposed | disassembled more reliably, a copper particle can be obtained more reliably.

The method for producing a wiring board of the present invention includes a liquid material forming step of forming a liquid material by dispersing the copper particles produced by the method for producing copper particles of the present invention in a dispersion medium,
An application step of applying the liquid material to a substrate;
After the coating step, there is a heat treatment step of performing a heat treatment on the substrate to form a wiring on the substrate.
Thereby, a highly reliable wiring board can be obtained.

Hereinafter, preferred embodiments of the copper formate complex, the method for producing copper particles, and the method for producing a wiring board of the present invention will be described in detail.
<Copper particles>
FIG. 1 is a schematic view showing the copper particles of the present invention.
As shown in FIG. 1, the copper particle 10 of the present invention is formed by bonding (coating) an aliphatic amine 12 to the surface of a granular nucleus 11 composed of zero-valent copper. The aliphatic amine 12 is bonded to the surface of the nucleus 11 with copper as the nucleus 11 side. Thereby, it can prevent that the copper particles 10 aggregate, and the copper particle 10 can exist stably.
Here, the copper particle 10 of the present invention has an average particle diameter (length D in FIG. 1) of about 0.5 to 120 nm, preferably about 1 to 20 nm. Since the average particle size is in this range, it is also called copper fine particles.

<Method for producing copper particles>
The manufacturing method of the copper particle 10 of this invention is the following general formula (1), for example.

（式中、Ｃｕは２価の銅、Ｒ^１およびＲ^２はそれぞれ置換基を有していてもよい脂肪族炭化水素基を示す。）で表されるギ酸銅錯体の、前記２価の銅が０価の銅に還元されるとともに、前記ギ酸配位子が二酸化炭素に酸化されるように前記ギ酸銅錯体を分解することにより銅粒子１０を得る方法である。これにより、ギ酸銅錯体が分解され、簡便に収率よく銅粒子１０を得ることができる。

(Wherein, Cu is divalent copper, and R ¹ and R ² each represents an aliphatic hydrocarbon group which may have a substituent) The divalent copper of the copper formate complex represented by Is reduced to zero-valent copper, and the copper formate 10 is obtained by decomposing the copper formate complex so that the formic acid ligand is oxidized to carbon dioxide. Thereby, a copper formate complex is decomposed | disassembled and the copper particle 10 can be obtained simply with sufficient yield.

First, the copper formate complex used for manufacturing the copper particles 10 will be described in detail.
The copper formate complex used for the production of the copper particles 10 is a compound represented by the general formula (1). Thereby, since the aliphatic amine ligand is coordinated to copper, the copper particles 10 modified with the aliphatic amine 12 can be obtained by decomposing the copper formate complex represented by the general formula (1). It can be easily obtained.

R ¹ and R ² in the general formula (1) are each an aliphatic hydrocarbon group which may have a substituent. Thereby, aggregation of the copper particle 10 obtained by decomposing | disassembling the copper formate complex represented by General formula (1) can be suppressed, and the stable and uniform copper particle 10 can be obtained.
Each of the aliphatic hydrocarbon groups represented by R ¹ and R ^{2 in} the general formula (1) preferably has 4 to 20 carbon atoms, and more preferably 6 to 20 carbon atoms. By setting the number of carbon atoms to 6 to 20, aggregation of the copper particles 10 obtained by decomposing the copper formate complex represented by the general formula (1) can be further suppressed, and the particle size is more stable and more uniform. Copper particles 10 can be obtained. Moreover, when the said copper particle 10 is contained in an ink, redispersibility becomes favorable.

In addition, examples of the aliphatic hydrocarbon group represented by R ¹ and R ^{2 in} the general formula (1) include a saturated aliphatic hydrocarbon group or an unsaturated aliphatic hydrocarbon group.
Examples of the saturated aliphatic hydrocarbon group include an alkyl group. For example, as an alkyl group, a butyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a hexadecyl group, a nonadecyl group or the like linear alkyl group, an isobutyl group, a 1-methylhexyl group, a 1-methyloctyl group, 1- Methyldecyl group, 1-methyldodecyl group, 1-ethyldodecyl group, 1-methylhexadecyl group, 1-methylnonadecyl group, tert-butyl group, 1,1-dimethylhexyl group, 1,1-dimethyloctyl group, 1, Examples thereof include branched alkyl groups such as 1-dimethyldecyl group, 1,1-dimethyldodecyl group, 1,1-dimethylhexadecyl group and 1,1-dimethylnonadecyl group.

  Examples of the unsaturated aliphatic hydrocarbon group include an alkenyl group and an alkynyl group. For example, as an alkenyl group, a linear alkenyl group such as 1-butenyl group, 1-hexenyl group, 1-octenyl group, 1-decenyl group, 1-dodecenyl group, 1-hexadecenyl group, 1-nonadecenyl group, isobutenyl group, 1-methyl-1-hexenyl group, 1-methyl-1-octenyl group, 1-methyl-1-decenyl group, 1-methyl-1-dodecenyl group, 1-methyl-1-hexadecenyl group, sec-butenyl group, 1,1-dimethyl-2-hexenyl group, 1,1-dimethyl-3-octenyl group, 1,1-dimethyl-4-decenyl group, 1,1-dimethyl-5-dodecenyl group, 1,1-dimethyl- Examples include branched alkenyl groups such as 6-hexadecenyl group.

  For example, as the alkynyl group, a linear alkynyl group such as a 2-butynyl group, a 2-hexynyl group, a 2-octynyl group, a 2-decynyl group, a 2-dodecynyl group, a 2-hexadecynyl group, a 2-nonadecynyl group, an isobutynyl group, 1-methyl-2-hexynyl group, 1-methyl-2-octynyl group, 1-methyl-2-decynyl group, 1-methyl-2-dodecynyl group, 1-methyl-2-hexadecynyl group, 1,1-dimethyl 2-hexynyl group, 1,1-dimethyl-3-octynyl group, 1,1-dimethyl-4-decynyl group, 1,1-dimethyl-5-dodecynyl group, 1,1-dimethyl-6-hexadecynyl group, etc. And a branched alkynyl group.

Of these, an alkyl group which is a saturated aliphatic hydrocarbon group is preferable, and a linear alkyl group is more preferable. Since it is an alkyl group, since it does not have an unsaturated bond, a stable copper formate complex represented by the general formula (1) can be obtained without causing side reactions. Moreover, since it is a linear alkyl group, since the steric hindrance of alkyl groups can be prevented or reduced, a much more stable copper formate complex can be obtained. Further, the copper particles 10 obtained by decomposing the copper formate complex represented by the general formula (1) are similarly stable and have a uniform particle size.
In addition, as long as the copper formate complex represented by the general formula (1) and / or the copper particles 10 are stably present in the aliphatic hydrocarbon groups represented by R ¹ and R ^{2 in} the general formula (1), substitution is performed. It may have a group. Examples of such a substituent include halogen atoms such as fluorine and chlorine, amino groups, and cyano groups.

Further, —NH ₂ R ¹ and —NH ₂ R ² in the general formula (1) may be either a primary amine ligand or a secondary amine ligand, respectively.
Examples of the primary amine ligand include butylamine, hexylamine, octylamine, decylamine, tridecylamine, hexadecylamine, nonadecylamine, 1-dodecenylamine, 2-dodecynylamine and the like.
Examples of secondary amine ligands include dipropylamine, dibutylamine, diamylamine, dihexylamine, dioctylamine, didecylamine, didodecylamine, ditetradecylamine, and dihexadecylamine.

  Of these amine ligands, primary amine ligands are particularly preferable. Thereby, the unmodified copper formate which is a raw material dissolves in the aliphatic primary amine, and the copper formate complex represented by the general formula (1) can be easily obtained. Moreover, since the steric hindrance between amine ligands can be prevented or reduced, a stable copper formate complex represented by the general formula (1) can be obtained. Further, the copper particles 10 obtained by decomposing the copper formate complex represented by the general formula (1) are similarly stable and have a uniform particle size.

Next, a method for producing such a copper formate complex represented by the general formula (1) will be described.
In general, it is known that unmodified copper formate dissolves in water, but does not dissolve in hydrophobic organic solvents. Therefore, when performing reaction using unmodified copper formate, a hydrophilic solvent such as water or alcohol is used as a reaction solvent. However, as a result of studying a simple method for producing a copper formate complex, the present inventors have surprisingly found that unmodified copper formate dissolves in a hydrophobic aliphatic amine. And it came to complete the method of manufacturing a copper formate complex simply without using a reaction solvent by this.

That is, the copper formate complex of the present invention represented by the general formula (1) can be obtained, for example, by dissolving unmodified copper formate in an aliphatic amine. Thereby, since the copper formate complex represented by the general formula (1) can be obtained only by the dissolving operation, the copper formate complex represented by the general formula (1) can be obtained in a very simple and high yield.
Here, the unmodified copper formate used in the production of the copper formate complex represented by the general formula (1) refers to an unmodified copper formate. Specific examples include copper formate, anhydrous copper formate, and copper formate hydrate. Of these, anhydrous copper formate is preferred. Thereby, reaction with an aliphatic amine advances appropriately and the copper formate complex represented by General formula (1) can be obtained reliably.
The amount of unmodified copper formate used in the reaction is preferably from 0.1 to 0.9 equivalent mol, more preferably from 0.2 to 0.5 equivalent mol, relative to 2 equivalent mol of the aliphatic amine. Thereby, reaction with an aliphatic amine advances reliably and the copper formate complex represented by General formula (1) can be obtained reliably.

On the other hand, the aliphatic amine used for the production of the copper formate complex represented by the general formula (1) is preferably an aliphatic amine having 4 to 20 carbon atoms, more preferably 6 to 20 carbon atoms. By setting the number of carbon atoms to 6 to 20, the carbon chain becomes long, so that a stable copper formate complex represented by the general formula (1) can be obtained.
The aliphatic amine may be either a saturated or unsaturated aliphatic amine, but is preferably a saturated aliphatic amine. Thereby, since an aliphatic amine does not have an unsaturated bond, the copper formate complex represented by General formula (1) can be obtained reliably, without causing a side reaction or the like.

  The aliphatic amine may be either a primary amine or a secondary amine, but a primary amine is preferable. Thereby, unmodified copper formate dissolves in the aliphatic amine, and the copper formate complex represented by the general formula (1) can be easily obtained. Moreover, since the steric hindrance between amines can be prevented or reduced, a stable copper formate complex represented by the general formula (1) can be obtained.

Examples of such aliphatic amines include the same amines as specifically described for the amine ligand.
The amount of the aliphatic amine used in the reaction is preferably 2.2 to 20 moles, more preferably 4 to 10 moles, per 1 mole of unmodified copper formate. Thereby, since reaction with unmodified copper formate advances reliably, the copper formate complex represented by General formula (1) can be obtained reliably.

Such unmodified copper formate is dissolved in the aliphatic amine, for example, by mixing them.
Specifically, in the case of an aliphatic amine having 4 to 11 carbon atoms, it is a liquid at room temperature (20 ° C.), and therefore formic acid represented by the general formula (1) by mixing with unmodified copper formate as it is. A copper complex can be obtained very simply.

On the other hand, in the case of an aliphatic amine having 12 to 20 carbon atoms, it is solid at room temperature (20 ° C.), so that the aliphatic amine is heated and melted or heated and pressurized and melted, and mixed with unmodified copper formate. The copper formate complex represented by the general formula (1) can be easily obtained.
The temperature at which the aliphatic amine is heated varies depending on the type of aliphatic amine, but may be heated to a temperature equal to or higher than the melting point of each aliphatic amine. Specifically, 30-80 degreeC is preferable and 40-60 degreeC is more preferable. By setting the heating temperature of the aliphatic amine within such a range, the aliphatic amine is melted and unmodified copper formate can be reliably dissolved.

Moreover, the time for mixing the aliphatic amine and the unmodified copper formate is preferably 0.5 to 2 hours, and more preferably 0.5 to 1 hour. Thereby, unmodified copper formate is reliably dissolved in the aliphatic amine, and the copper formate complex represented by the general formula (1) can be obtained with certainty.
In order to crystallize the copper formate complex represented by the general formula (1) obtained by mixing unmodified copper formate and an aliphatic amine, a poor solvent may be added to the reaction solution. Examples of such a poor solvent include hydrocarbon solvents such as dodecane and decalin. Thereby, a beautiful acicular crystal can be obtained.

Since the unmodified copper formate is dissolved in the aliphatic amine by the method as described above, the copper formate complex represented by the general formula (1) can be easily obtained in a high yield.
By the way, as described above, the copper particles 10 can be obtained by decomposing the copper formate complex represented by the general formula (1) thus obtained.
Specifically, as shown in the following formula, a copper formate complex solution in which a copper formate complex represented by the general formula (1) is dissolved in an organic solvent is used, and the divalent copper of the copper formate complex is zero-valent copper. And the formic acid ligand is decomposed to be oxidized to carbon dioxide. Thereby, the copper particle 10 in which the amine ligand of the copper formate complex represented by the general formula (1) functions as a modifier can be easily obtained with high yield.

  Here, the organic solvent for dissolving the copper formate complex is not particularly limited as long as the copper formate complex can be dissolved. Specifically, the aliphatic amine described for the amine ligand, alcohol solvent such as methanol, ethanol, propanol or butanol, propylene carbonate, γ-butyrolactone, N-methyl-2-pyrrolidone, dimethylformamide, dimethyl sulfoxide And polar solvents such as cyclohexanone. Of these, aliphatic amines are preferred. Thereby, since the ligand of the copper formate complex represented by the general formula (1) and the solvent are of the same type, when the aliphatic amine of the solvent is bonded to copper, one type of copper particle 10 is added to the copper particle 10. A modifier can be attached. Moreover, since the aliphatic amine 12 of the solvent binds to copper as a modifier, it is possible to reliably obtain the copper particles 10 that are more efficient and less aggregated.

In addition, the usage-amount of the copper formate complex used for the decomposition reaction of copper formate will not be specifically limited if it is the quantity melt | dissolved in the said organic solvent.
The decomposition of the copper formate complex represented by the general formula (1) is not particularly limited as long as the copper of the copper formate complex is reduced to zero valence and the formic acid ligand is oxidized to carbon dioxide. It is preferable to heat to near the decomposition temperature of the copper complex or above the decomposition temperature. Thereby, copper of the copper formate complex represented by the general formula (1) is reliably reduced to zero valence, and the formic acid ligand is oxidized to carbon dioxide. Therefore, the copper particles 10 can be easily obtained with a high yield.

The heating temperature of the copper formate complex represented by the general formula (1) is preferably 70 to 250 ° C, and more preferably 70 to 200 ° C. Thereby, copper in the copper formate complex represented by the general formula (1) is more reliably reduced to zero valence, and the formic acid ligand is oxidized to carbon dioxide. Therefore, the copper particle 10 with a good yield can be obtained reliably.
The heating time of the copper formate complex represented by the general formula (1) varies depending on the heating temperature of the copper formate complex. For example, when the heating temperature of the copper formate complex represented by the general formula (1) is high, the heating time of the copper formate complex may be set short. Moreover, what is necessary is just to set the heating time of the said copper formate complex long when the heating temperature of the copper formate complex represented by General formula (1) is low. As specific time, 0.1 to 10 hours are preferable, and 0.5 to 4 hours are more preferable. This ensures that the copper in the copper formate complex represented by the general formula (1) is reduced to zero and the formic acid ligand is oxidized to carbon dioxide. Therefore, it is possible to reliably obtain the copper particles 10 with a high yield.

  Moreover, it is preferable that the atmosphere at the time of heating the copper formate complex represented by General formula (1) is inert gas atmosphere, such as argon gas and nitrogen gas, for example. Thereby, it is possible to reliably prevent the formed nucleus 11 (copper) from being oxidized. As a result, for example, when a wiring board as described later is formed using the copper particles 10, it is possible to prevent the resistivity of the wiring board from increasing.

In addition, decomposition | disassembly of the copper formate complex represented by General formula (1) reduces the copper of the said copper formate complex to 0 valence by using an oxidizing agent, a reducing agent, etc. besides the said heating, and formic acid coordination It can also be decomposed by reducing the child to carbon dioxide.
As mentioned above, according to the manufacturing method of the copper particle 10 of this invention, since the copper particle 10 can be manufactured with sufficient yield only by decomposing | disassembling the copper formate complex represented by General formula (1), copper The production efficiency of the particles 10 can be improved.

Moreover, the manufacturing method of the copper particle 10 of this invention can also be performed following the method of making unmodified copper formate and an aliphatic amine react, and manufacturing the copper formate complex represented by General formula (1).
That is, the method for producing copper particles 10 of the present invention includes a first step of obtaining a copper formate complex represented by the general formula (1) by dissolving unmodified copper formate in an aliphatic amine, and the copper formate. A second step of obtaining copper particles 10 by decomposing the copper formate complex so that the divalent copper of the complex is reduced to zero-valent copper and the formate ligand is oxidized to carbon dioxide. It may be a method of having. Thereby, since the 1st process and the 2nd process are performed continuously using an inexpensive raw material, copper particles can be obtained with a low cost and a high yield in one pot.

In the method for producing the copper particles 10, the reaction solution in the first step may be used as it is in the second step, and after isolating the copper formate complex obtained in the first step, It may be dissolved and used in the second step.
By using the reaction solution in the first step as it is in the second step, the reaction can be carried out in the same system, so that copper particles can be obtained very easily and with a high yield in one pot.

Moreover, since the copper formate complex obtained in the first step is once isolated and then dissolved in an organic solvent and used in the second step, the copper formate 10 having few impurities can be obtained because it is purified. it can.
In addition, the thing similar to what was demonstrated by the manufacturing method of the said copper formate complex is mentioned as this organic solvent.

Thus, since the manufacturing method of the copper particle 10 of this invention can obtain the copper particle 10 only by mixing, melt | dissolving, and heating the cheap raw material of copper formate and an aliphatic amine, the production efficiency of the copper particle 10 is obtained. Can be further improved.
The copper particles 10 obtained by the manufacturing method as described above are applied, for example, in the semiconductor device field by being contained in ink. Specifically, TFT (transistor), LCD (liquid crystal display), and AMBP (alpha-1-microglobulin / bikunin precursor) are mentioned. Organic PCB (Polychlorinated Biphenyl) has application of metal ink. Moreover, it is applied to various uses such as formation of conductive patterns such as wiring and electrodes, antibacterial agents, and deodorants.

<Manufacturing method of wiring board>
Next, the manufacturing method of the wiring board of this invention is demonstrated with reference to figures.
FIG. 2 is a diagram for explaining a manufacturing process of a method for manufacturing a wiring board according to the present invention, and FIG. 3 is a schematic perspective view of a wiring forming apparatus used in the method for manufacturing a wiring board according to the present invention. In the following description, the upper side in FIGS. 2 and 3 is referred to as “upper” and the lower side is referred to as “lower”.
First, as shown in FIG. 1 (S1), a substrate 101 on which wiring is to be formed is prepared.
As such a substrate 101, various substrates such as silicon, quartz glass, glass, plastic film, and metal can be used. Further, a semiconductor film, a metal film, a dielectric film, an organic film, or the like may be formed on the substrate surface as a base layer.

(Liquid material forming process)
In the present embodiment, a liquid material 21 that is a dispersion liquid in which copper particles 10 are dispersed in a dispersion medium is used.
In order to disperse the copper particles 10, the surface of the copper particles 10 can be coated with an organic substance or the like. Moreover, when apply | coating to the board | substrate 101, it is preferable that the particle size of the copper particle 10 is 1-20 nm from a viewpoint of the dispersibility to a dispersion medium and the application of an inkjet method.

  Next, a liquid material 21 in which the copper particles 10 are dispersed in a dispersion medium is prepared. The dispersion medium used here preferably has a vapor pressure of 0.001 to 200 mmHg at room temperature. This is because when the vapor pressure is higher than 200 mmHg, the dispersion medium evaporates first when forming the coating film, making it difficult to form a good coating film. On the other hand, in the case of a dispersion medium having a vapor pressure lower than 0.001 mmHg at room temperature, drying becomes slow, and the components of the dispersion medium tend to remain in the coating film, and a high-quality conductive film after heat and / or light treatment in the subsequent process. Is difficult to obtain. Moreover, when the liquid material 21 is applied by an ink jet apparatus described later, the vapor pressure of the dispersion medium is preferably 0.001 to 50 mmHg. This is because when the vapor pressure is higher than 50 mmHg, nozzle clogging due to drying is likely to occur when droplets are ejected from the ink jet apparatus, and stable ejection becomes difficult. On the other hand, when the vapor pressure is lower than 0.001 mmHg, drying of the ejected ink is delayed, and the component of the dispersion medium tends to remain in the conductive film, and it is difficult to obtain a high-quality conductive film even after the heat treatment in the subsequent step.

  The dispersion medium to be used is not particularly limited as long as it can disperse the copper particles 10 and does not cause aggregation. In addition to the organic solvent described above, water, n-heptane, n-octane, decane, Hydrocarbon solvents such as toluene, xylene, cymene, durene, indene, dipentene, tetrahydronaphthalene, decahydronaphthalene, cyclohexylbenzene, decalin, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol methyl ethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl Examples include ether solvents such as ether, diethylene glycol methyl ethyl ether, 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, and p-dioxane. It is possible. Of these, water, alcohols, hydrocarbon solvents, and ether solvents are preferred and more preferred dispersions in view of the dispersibility of the copper particles 10, the stability of the dispersion, and the ease of application to the ink jet method. Examples of the medium include water and hydrocarbon solvents. These dispersion media can be used alone or as a mixture of two or more.

The dispersion density of the dispersoid (copper particles 10) when the copper particles 10 are dispersed in a dispersion medium is appropriately selected depending on the method of applying the liquid material 21 to the substrate 101. The dispersion density of the dispersoid is not particularly limited, but is preferably 1 to 80% by weight. Thereby, it can adjust according to the film thickness of the functional film 22 desired.
In particular, in the case of the ink jet method described later, since fluidity and quick drying of the ink are required, the dispersion density of the dispersoid is preferably 10 to 80% by weight, and more preferably 30 to 70% by weight. When the dispersion density of the dispersoid exceeds the upper limit value, the copper particles 10 are likely to aggregate, and the fluidity of the liquid material 21 is lowered. On the other hand, when the dispersion density of the dispersoid is lower than the lower limit, the quick drying property decreases.

The liquid material 21 in which the copper particles 10 are dispersed can be added with a small amount of a surface tension adjusting agent such as a fluorine-based material, a silicone-based material, or a non-ionic material, as long as the target function is not impaired. The nonionic surface tension modifier improves the wettability of the liquid material 21 to the application object, improves the leveling property of the applied film, and helps prevent the occurrence of coating crushing and itching. It is.
The viscosity of the liquid material 21 in which the copper particles 10 thus prepared are dispersed is preferably 1 to 50 mPa · s. Thereby, a desired functional film 22 can be obtained.

  In particular, in the case of the ink jet method described later, fluidity and quick drying of the ink are required, and thus the viscosity of the liquid material 21 is preferably 2 to 40 mPa · s, and more preferably 5 to 20 mPa · s. If the viscosity of the liquid material 21 exceeds the upper limit, the copper particles 10 are likely to aggregate and the fluidity of the liquid material 21 is reduced. In addition, the clogging frequency at the nozzle holes increases, and it becomes difficult to smoothly discharge droplets. On the other hand, when the viscosity of the liquid material 21 is lower than the lower limit, the quick drying property is lowered. In addition, the peripheral portion of the nozzle is easily contaminated by the outflow of ink.

  Further, the surface tension of the liquid material 21 in which the copper particles 10 thus prepared are dispersed is preferably in the range of 20 to 70 dyn / cm. When the liquid material 21 is applied by an ink jet apparatus described later, if the surface tension is less than 20 dyn / cm, the wettability of the ink composition with respect to the nozzle surface increases, and thus flight bending easily occurs and exceeds 70 dyn / cm. This is because the shape of the meniscus at the nozzle tip is not stable, and it becomes difficult to control the discharge amount and discharge timing of the ink composition.

(Coating process)
Next, as shown in FIG. 1 (S2), the liquid material 21 containing the copper particles 10 of the present invention is applied onto the substrate 101, preferably by an ink jet method. Thereby, it is possible to form a pattern at a time without having a mask forming step and a mask removing step necessary for other coating methods. Moreover, a complicated shape and a pattern with a fine shape can be easily formed.

  However, the coating method in the present invention is not limited to such an ink jet method, for example, spin coating method, casting method, micro gravure coating method, gravure coating method, bar coating method, roll coating method, wire bar coating method, dip coating method. Various coating methods such as spray coating, screen printing, flexographic printing, and offset printing can also be used.

The interval between the ink droplets applied on the substrate 101 is controlled by controlling the ejection frequency and the relative speed of the inkjet head and the substrate 101. In particular, it is preferable that ink droplets adjacent to each other in the same wiring are applied so as to cause an overlap of 1 to 10% of the diameter of the liquid material 21 when applied onto the substrate 101. In other words, the interval between the ink droplets is preferably 90 to 99% of the diameter of the liquid material 21 when applied onto the substrate 101. If the interval between the ink droplets is narrower and the overlap is larger than this, a bulge is generated and a good line cannot be formed. On the other hand, if the interval between the ink droplets is wider and the overlap is smaller, the overlap of the liquid material 21 does not occur due to the ejection position accuracy error, and the cut wiring 22 may be formed. The device 100 for forming the wiring 22 will be described later.
Thus, by using the liquid material 21 containing the copper particles 10, the wiring 22 having uniform and excellent characteristics can be applied.

(Heat treatment process)
As shown in FIG. 1 (S3), the substrate 101 on which the liquid material 21 in which the copper particles 10 are dispersed is applied in a predetermined pattern to remove the dispersion medium and improve the electrical contact between the copper particles 10. And subjected to heat treatment. The heat treatment is usually performed in the air, but can also be performed in an inert gas atmosphere such as nitrogen, argon, or helium as necessary. The treatment temperature of the heat treatment may be appropriately determined depending on the boiling point (vapor pressure) of the dispersion medium, the pressure, and the thermal behavior of the copper particles 10, and is not particularly limited, but is preferably performed at room temperature to 300 ° C or less. . When using a substrate 101 such as plastic, it is preferably performed at room temperature to 100 ° C.
Further, the heat treatment may be performed twice or more. In that case, for example, the first time is performed at a low temperature that can remove the dispersion medium (drying), and the second time is performed at a high temperature (baking). The dispersion medium can be removed by heat treatment at a low temperature. Subsequently, by performing a heat treatment at a high temperature, a copper substrate 10 is aged and a wiring board excellent in electrical contact can be obtained.

The time for performing the heat treatment (total time in the case of performing plural times) is not particularly limited, but is preferably 5 minutes to 5 hours. Thereby, a dispersion medium is removed and the wiring board excellent in electrical contact can be obtained.
The heat treatment can be performed by lamp annealing in addition to the treatment by a normal hot plate, electric furnace or the like. The light source used for lamp annealing is not particularly limited, but excimer laser such as infrared lamp, xenon lamp, YAG laser, argon laser, carbon dioxide laser, XeF, XeCl, XeBr, KrF, KrCl, ArF, ArCl, etc. Can be used as a light source. These light sources generally have an output in the range of 10 to 5000 W, but a range of 100 to 1000 W is sufficient in the present embodiment.

The functional film (wiring) 22 is formed by the above process.
In addition, when a desired film thickness cannot be obtained by one application process and heat treatment process, the application process and the heat treatment process may be performed a plurality of times to laminate the films. For example, the wiring board can be manufactured in the order of application of the liquid material 21 to the substrate 101, heat treatment (drying), application, and heat treatment (firing). Thereby, a wiring board having a desired thickness can be obtained.

The film thickness of the wiring 22 is preferably 0.1 to 10 μm, and more preferably 1 to 5 μm. If the film thickness is larger than the upper limit, the production of the wiring board is complicated, and the uniformity of the wiring 22 is lowered. On the other hand, when the film thickness is thinner than the lower limit value, the resistance value tends to increase.
In this way, by performing the heat treatment, it is possible to form a thin and thick wiring board without generating bulges.

(Wiring forming equipment)
Next, a wiring forming apparatus used in the coating process will be described.
FIG. 2 is a schematic perspective view of a wiring forming apparatus used in the method for manufacturing a wiring board according to the present invention. The wiring forming apparatus 100 includes an ink jet type liquid application device, and includes an ink jet head group 1, an X direction drive shaft 4, a Y direction guide shaft 5, a control device 6, a mounting table 7, a cleaning mechanism unit 8, and a base 9. And a heater 15.

The ink jet head group 1 includes a head as an ink jet application unit that discharges a predetermined liquid from a nozzle (discharge port) and applies the liquid to the substrate 101 at a predetermined interval.
The mounting table 7 is for mounting the substrate 101 to which the liquid material 21 is applied by the coating device, and includes a mechanism for fixing the substrate 101 at a reference position.
An X-direction drive motor 2 is connected to the X-direction drive shaft 4. The X direction drive motor 2 is a stepping motor or the like, and rotates the X direction drive shaft 4 when a drive signal in the X axis direction is supplied from the control device 6. When the X direction drive shaft 4 is rotated, the inkjet head group 1 moves in the X axis direction.

  The Y-direction guide shaft 5 is fixed so as not to move with respect to the base 9. The mounting table 7 includes a Y-direction drive motor 3. The Y-direction drive motor 3 is a stepping motor or the like, and moves the mounting table 7 in the Y-axis direction when a drive signal in the Y-axis direction is supplied from the control device 6. The control device 6 supplies a droplet discharge control voltage to each head of the inkjet head group 1. Further, a drive pulse signal for controlling the movement of the inkjet head group 1 in the X-axis direction is supplied to the X-direction drive motor 2, and a drive pulse signal for controlling the movement of the mounting table 7 in the Y-axis direction is supplied to the Y-direction drive motor 3. .

The cleaning mechanism unit 8 includes a mechanism for cleaning the inkjet head group 1. The cleaning mechanism unit 8 includes a Y-direction drive motor (not shown). The cleaning mechanism 8 moves along the Y-direction guide shaft 5 by driving the Y-direction drive motor. The movement of the cleaning mechanism unit 8 is also controlled by the control device 6.
Here, the heater 15 is a means for heat-treating the substrate 101 by lamp annealing, and evaporates and dries the liquid material 21 applied on the substrate 101 and converts it into a functional material film. The control device 6 controls the turning on and off of the heater.
According to the film pattern forming apparatus 100 of the present embodiment, a thin line and thick film pattern can be formed without generating bulges.

<Wiring board>
The wiring board manufactured by the above method will be described.
FIG. 4 shows a planar layout of signal electrodes and the like (wiring substrate) on the first substrate of the liquid crystal device. Such a liquid crystal device includes a first substrate, a second substrate (not shown) provided with scanning electrodes and the like, and a liquid crystal (not shown) sealed between the first substrate and the second substrate. It is roughly structured.

As shown in FIG. 4, a plurality of signal electrodes 310 are provided in a multiple matrix form in the pixel region 303 on the first substrate 300. In particular, each signal electrode 310 includes a plurality of pixel electrode portions 310a provided corresponding to each pixel and a signal wiring portion 310b connecting them in a multiplex matrix shape, and extends in the Y direction.
Reference numeral 350 denotes a one-chip liquid crystal driving circuit. The liquid crystal driving circuit 350 and one end side (lower side in the figure) of the signal wiring portion 310 b are connected via a first routing wiring 331.

Reference numeral 340 denotes a vertical conduction terminal. The vertical conduction terminal 340 and a terminal provided on a second substrate (not shown) are connected by a vertical conduction material 341. In addition, the vertical conduction terminal 340 and the liquid crystal driving circuit 350 are connected via the second routing wiring 332.
In the present embodiment, the signal wiring portion 310b, the first routing wiring 331, and the second routing wiring 332 provided on the first substrate 300 are each formed by the wiring substrate manufacturing method using the wiring forming apparatus 100. Is formed. According to the present liquid crystal device, it is possible to obtain a liquid crystal device that is less likely to cause a failure such as disconnection or short circuit of the respective wirings, and that can be reduced in size and thickness.

As mentioned above, although the manufacturing method of the copper particle of this invention, the copper formate complex, and the manufacturing method of a wiring board were demonstrated based on suitable embodiment, this invention is not limited to these.
For example, in the method for producing copper particles of the present invention, one or two or more optional steps may be added.
In the method for manufacturing a wiring board according to the present invention, one or two or more arbitrary steps may be added.

Next, specific examples of the present invention will be described.
I. Production of copper particles (Example 1)
<1> Production of copper formate complex A mixture (50 g) of copper formate tetrahydrate and copper formate dihydrate was placed in a 55 ° C. vacuum thermostat and dried until there was no change in weight. Thereby, anhydrous copper formate was obtained. On the other hand, dodecylamine (20 g) was put in a sample bottle and dissolved in a thermostatic bath at 50 ° C.

Next, the obtained anhydrous copper formate (50 mg) was added to the dissolved dodecylamine, covered with a sample bottle, and placed in a thermostatic bath at 50 ° C. After about 2 hours, a clear blue solution was formed.
Next, acetonitrile (30 g) was added to precipitate a crystalline solid. The lid was put on again, and the sample bottle was put into a constant temperature bath at 50 ° C. again. After about 1 hour, a blue transparent solution was formed again. As a result of taking out the sample bottle from the thermostatic chamber and performing natural cooling to room temperature (20 ° C.), needle-like crystals were obtained. The needle crystals were collected by filtration, washed with acetonitrile, and then vacuum dried. As a result, a complex of copper formate / dodecylamine was obtained in a yield of 94%.
<2> Production of copper particles The copper formate / dodecylamine complex obtained in <1> was dissolved in dodecylamine and heated to 120 ° C. Thereby, copper particles were obtained with a yield of 95%.

(Example 2)
In Example 1, except having replaced decylamine with hexylamine, it carried out similarly to Example 1 and obtained the copper particle with the yield of 89%. Since hexylamine is a liquid at room temperature (20 ° C.), it was used as it was without being placed in a thermostatic bath at 50 ° C.
(Example 3)
In Example 1, except having replaced dodecylamine with octylamine, it carried out like Example 1 and obtained the copper particle by 91% of yield. In addition, since octylamine is a liquid at room temperature (20 ° C.), it was used as it was without being placed in a thermostatic bath at 50 ° C.

Example 4
In Example 1, except having replaced the dodecylamine with the decylamine, it carried out similarly to Example 1 and obtained the copper particle with the yield of 90%. Since decylamine is a liquid at room temperature (20 ° C.), it was used as it was without being placed in a thermostatic bath at 50 ° C.
(Example 5)
In Example 1, except having replaced the dodecylamine with the hexadecylamine, it carried out similarly to Example 1 and obtained the copper particle with the yield of 91%.

(Comparative Example 1)
A mixture (50 g) of copper formate tetrahydrate and copper formate dihydrate was placed in a 55 ° C. vacuum thermostat and dried until there was no change in weight. Thereby, anhydrous copper formate was obtained.
The obtained anhydrous copper formate (50 mg) was added to 2,6 dimethylpyridine, which is a heteroaromatic compound, covered with a sample bottle, and placed in a thermostatic bath at 50 ° C. However, anhydrous copper formate was not dissolved in 2,6 dimethylpyridine, and copper particles were not obtained.

II. Evaluation of Copper Particles The copper formate / dodecylamine complex obtained in Example 1 was loaded on an alumina pan and analyzed using a thermal analyzer (TA Instruments Q500 type).
The measurement conditions for thermal analysis (TGA) are a nitrogen flow rate of 40 ml / min and a temperature increase condition of 20 ° C./min.
The result of thermal analysis is shown in FIG. As shown in FIG. 5, the weight of the copper formate / dodecylamine complex rapidly decreased at about 120 ° C., and decreased to 90.8% (calculated value: 87.9%) up to about 370 ° C. . Two peaks were obtained at about 138 ° C to 160 ° C.

From the above, it was confirmed that the formic acid ligand of the copper formate / dodecylamine complex was oxidized to carbon dioxide by the heating of the copper formate / dodecylamine complex, the copper was reduced to zero valence, and the copper particles were produced. It was done.
Moreover, the average particle diameter of the copper particle obtained in Example 1 was measured using the transmission electron microscope (JEM 2000EX by JEOL). As a result, the average particle size was 8 nm.
In addition, the copper particles of Examples 2 to 5 were performed in the same manner, and it was confirmed that the copper particles were produced with the same average particle diameter.

III. Production of wiring board (Example 6)
The copper particles produced in Example 1 were dispersed in decalin so as to be 60 wt%. Inkjet ink (liquid material) was prepared by further adding dodecylbenzene thereto. The viscosity of the prepared ink was 12 mPa · s. Then, this ink was ejected onto a glass substrate in a line pattern in a glove box under an argon gas atmosphere by using a line pattern, and then heated and dried at 100 ° C. to form a film. Further, a film forming (laminating) operation was similarly repeated on this film to make the film thickness 1.2 μm. Next, the obtained film was baked at 300 ° C. for 30 minutes in a glove box under an argon gas atmosphere to sinter the nuclei.
Through the above steps, a wiring having a line width of 50 μm and a thickness of 1 μm was formed on the substrate.

(Example 7)
In Example 6, except having used the copper particle obtained in Example 2, it carried out similarly to Example 6 and obtained the wiring board.
(Example 8)
In Example 6, except having used the copper particle obtained in Example 3, it carried out similarly to Example 6 and obtained the wiring board.

Example 9
In Example 6, except having used the copper particle obtained in Example 4, it carried out similarly to Example 6 and obtained the wiring board.
(Example 10)
In Example 6, except having used the copper particle obtained in Example 5, it carried out similarly to Example 6 and obtained the wiring board.

IV. Evaluation of Wiring Substrate When the wiring substrates obtained in Examples 6 to 10 were inspected, good quality wiring without defects (defects) such as cracks and pinholes, disconnection, and short circuit was obtained. Also, the dimensional accuracy of the wiring was high.

It is a schematic diagram which shows the copper particle of this invention. It is a figure for demonstrating the manufacturing method of the wiring board of this invention. It is a schematic perspective view of the wiring formation apparatus used for the manufacturing method of the wiring board of this invention. It is a top view which shows the wiring board manufactured by the manufacturing method of the wiring board of this invention. FIG. 3 is a diagram showing a thermal analysis result of the copper particles obtained in Example 1. The left vertical axis in the figure represents the weight (%) of the copper formate complex, the vertical axis in the figure represents the weight of the copper particles (% / ° C), and the horizontal axis represents the temperature (° C).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Inkjet head group 2 ... X direction drive motor 3 ... Y direction drive motor 4 ... X direction drive shaft 5 ... Y direction guide shaft 6 ... Control device 7 ... Mounting table 8 ... Cleaning mechanism 9. Base 10 ... Copper particles 11 ... Core 12 ... Aliphatic amine 15 ... Heater 21 ... Liquid material 22 ... Functional film (wiring) 100 ... Wiring forming device 101 ... Substrate 300 ... First substrate 303 Pixel area 310 Signal electrode 310a Pixel electrode section 310b Signal wiring section 331 First routing wiring 332 Second routing wiring 340 Vertical conduction terminal 341 Vertical Conductive material 350 ... Liquid crystal drive circuit D ... Average particle size

Claims (11)

The following general formula (1)

(In the formula, Cu represents divalent copper, and R ¹ and R ² each represents an aliphatic hydrocarbon group which may have a substituent.)
The copper formate complex characterized by these. The copper formate complex according to claim 1, wherein R ¹ and R ² in the general formula (1) each have 4 to 20 carbon atoms. The copper formate complex according to claim 1, wherein —NH ₂ R ¹ and —NH ₂ R ² in the general formula (1) are each a primary amine ligand.   The copper aliphatic formate complex according to any one of claims 1 to 3, wherein the aliphatic hydrocarbon group is an alkyl group. The following general formula (1)

(In the formula, Cu represents divalent copper, and R ¹ and R ² each represents an aliphatic hydrocarbon group which may have a substituent.)
The divalent copper of the copper formate complex represented by the formula is reduced to zero valent copper, and the copper formate complex is decomposed so that the formic acid ligand is oxidized to carbon dioxide. A method for producing copper particles, comprising: obtaining a copper particle. By dissolving unmodified copper formate in an aliphatic amine, the following general formula (1)

(In the formula, Cu represents divalent copper, and R ¹ and R ² each represents an aliphatic hydrocarbon group which may have a substituent.)
A first step of obtaining a copper formate complex represented by:
Second, obtaining the copper particles by decomposing the copper formate complex so that the divalent copper of the copper formate complex is reduced to zero-valent copper and the formic acid ligand is oxidized to carbon dioxide. The process of manufacturing a copper particle characterized by including these processes.   The method for producing copper particles according to claim 6, wherein the unmodified copper formate is dissolved by heating.   The method for producing copper particles according to claim 6 or 7, wherein the aliphatic amine is a saturated aliphatic amine having 4 to 20 carbon atoms.   The method for producing copper particles according to any one of claims 5 to 8, wherein the decomposition of the copper formate complex is performed by heating to near the decomposition temperature of the copper formate complex or higher than the decomposition temperature.   The method for producing copper particles according to claim 9, wherein a heating temperature of the copper formate complex is 70 to 200 ° C. A liquid material forming step of forming a liquid material by dispersing the copper particles produced by the method for producing copper particles according to any one of claims 5 to 10 in a dispersion medium;
An application step of applying the liquid material to a substrate;
A method of manufacturing a wiring board, comprising: after the coating step, performing a heat treatment on the substrate to form a wiring on the substrate.

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