JP5045015B2 - Method for producing copper formate, method for producing copper particles, and method for producing wiring board - Google Patents

Description

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

In recent years, functional liquid materials containing metal nanoparticles have attracted attention. In particular, materials using copper nanoparticles that are more advantageous in terms of cost than silver nanoparticles have attracted attention.
In general, copper formate is used as a starting material for copper nanoparticles. Such copper formate is produced based on an acid-base reaction of, for example, cupric carbonate or cupric hydroxide with formic acid or methyl formate (for example, Patent Document 1).

However, such a method has a problem in terms of the purity of copper formate, because cupric carbonate, cupric hydroxide, and the like contain impurities such as alkali metals such as sodium and potassium. Moreover, the said method is not necessarily a simple method, and is a method with a problem also in cost.
Therefore, it is required to easily produce high purity copper formate in one step.

US Pat. No. 5,093,510

  An object of the present invention is to provide a method for efficiently producing copper formate, a method for producing copper particles using the method, and a method for producing a wiring board using a liquid material in which the copper particles are dispersed. .

Such an object is achieved by the present invention described below .

The method for producing copper formate of the present invention comprises a first step of obtaining formic acid by reacting formic acid with an oxidizing agent;
It has the 2nd process of making the said formic acid and copper react and obtaining copper formate.
Thereby, after manufacturing a formic acid, since a formic acid and copper are made to react, copper formate can be obtained more reliably and with a sufficient yield. Moreover, since the reaction liquid of a 1st process can be used for a 2nd process as it is, copper formate can be easily obtained with low productivity from a cheap material with one pot. Furthermore, if the formic acid obtained in the first step is purified by distillation and used in the second step, copper formate with fewer impurities can be obtained.

In the method for producing copper formate of the present invention, the copper is preferably copper having a purity of 99% or more.
Thereby, high purity copper formate can be obtained.
In the method for producing copper formate according to the present invention, the oxidizing agent is preferably formic acid, hydrogen peroxide, ozone or singlet oxygen.
Thereby, since it is an oxidizing agent with strong oxidizing power, copper can be reliably oxidized to divalent copper, and copper formate can be obtained reliably and in a high yield. Moreover, since formic acid can be oxidized to produce performic acid, copper can be more reliably oxidized to divalent copper with the formic acid and the oxidizing agent. Furthermore, since an oxidizing agent composed only of carbon, hydrogen or oxygen is used, copper formate with less impurities can be obtained without polluting the environment.

（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製造する第２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製造する第３の工程とを有することを特徴とする。
これにより、各工程の生成物を単離することなく次工程に進むことができるため、極めて簡便かつ収率よく銅粒子を得ることができる。また、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。さらに、修飾剤として脂肪族のアミンを用いているため、均一な粒径の銅粒子を得ることができる。 In the method for producing copper formate according to the present invention, the copper formate obtained by the method for producing copper formate according to the present invention is preferably for producing copper particles.
Thereby, high purity and high quality copper particles can be obtained.
The method for producing copper particles of the present invention includes a first step of obtaining copper formate by the method for producing copper formate of the present invention,
By dissolving the 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 second step of producing a copper formate complex represented by:
The copper formate is produced 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. And a third step.
Thereby, since it can progress to a next process, without isolating the product of each process, a copper particle can be obtained very simply and with a sufficient yield. Moreover, since an inexpensive material is used, copper particles can be obtained at low cost. Furthermore, since an aliphatic amine is used as the modifier, copper particles having a uniform particle size 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 is obtained.

Hereinafter, preferred embodiments of a method for producing copper formate, a method for producing copper particles, and a method for producing a wiring board according to the present invention will be described in detail.
<Method for producing copper formate>
The method for producing copper formate of the present invention is, for example, a method for obtaining copper formate by reacting formic acid, copper, and an oxidizing agent. Thus, copper is oxidized by the oxidizing agent, and the oxidized copper reacts with formic acid, whereby copper formate can be easily obtained with a high yield. Further, formic acid is oxidized by the oxidizing agent, and copper is oxidized by the oxidized formic acid (performic acid). The oxidized copper reacts with formic acid generated by reduction of formic acid and / or performic acid in the reaction system, so that copper formate can be easily obtained with a high yield.

Here, the formic acid used in the reaction is preferably used in an amount of 2 to 500 mol, more preferably 3 to 100 mol, per 1 mol of copper. By using formic acid in such a range, oxidized copper is sufficiently dissolved and reacted, so that copper formate can be obtained reliably.
Copper used for the reaction is metallic copper, and its valence is zero. Such copper is preferably high-purity copper. Specifically, 99% or more is preferable, and 99.5% or more is more preferable. By using such high purity copper, high purity copper formate can be obtained. Moreover, if this copper formate is used, a highly purified copper particle can also be manufactured. These effects are remarkably obtained by using copper having a purity of 99.5% or more.

Moreover, it is preferable that the copper used for reaction is a powder form. Specifically, the average particle size is preferably 0.5 to 20 μm, and more preferably 1 to 5 μm. By using an average particle diameter in such a range, it reacts with the oxidizing agent more efficiently, so that copper formate can be reliably obtained.
Such copper is preferably used in an amount of 0.1 to 0.9 mol, more preferably 0.2 to 0.8 mol, with respect to 2 equivalents of oxidizing agent. By using copper in such a range, since it reacts reliably with an oxidizing agent, copper formate can be reliably obtained.

Although the oxidizing agent used for reaction is not specifically limited, When oxidizing copper, it is preferable that it is an oxidizing agent with strong oxidizing power. Thereby, since 0 valent copper can be reliably made into bivalent copper, copper formate can be obtained with sufficient yield.
Examples of such an oxidizing agent having a strong oxidizing power include performic acid, ozone, singlet oxygen, and the like. Of these, performic acid is preferred. Thereby, 0 valence copper can be reliably changed to divalent copper. Moreover, since formic acid itself is reduced to formic acid, copper formate can be efficiently obtained only with copper and formic acid which is an oxidizing agent. Furthermore, since performic acid can be obtained only by oxidizing formic acid, it can be obtained easily at low cost.

In the case of oxidizing formic acid, hydrogen peroxide, ozone, singlet oxygen and the like are mentioned in addition to the oxidizing agent having strong oxidizing power. Of these, hydrogen peroxide composed of hydrogen and oxygen is preferred. Thereby, since the product produced | generated by reaction is hydrogen, oxygen, or water, it can be set as the reaction in consideration of the environment.
Such an oxidizing agent is preferably used in an amount of 2.2 to 20 equivalents, more preferably 2.5 to 10 equivalents, per 1 mol of copper. By using an oxidizing agent in such a range, it is possible to reliably oxidize copper or formic acid with a high yield, so that copper formate can be reliably obtained.

The time for reacting formic acid, copper, and oxidizing agent is preferably 0.5 to 30 hours, and more preferably 1 to 15 hours. By carrying out the reaction within such a reaction time, copper is oxidized to divalent copper, and copper formate can be obtained with good yield.
Moreover, 0-40 degreeC is preferable and, as for the temperature which makes formic acid, copper, and an oxidizing agent react, 0-20 degreeC is more preferable. By carrying out the reaction within such a reaction time, copper is oxidized to divalent copper, and copper formate can be obtained with good yield. Moreover, unstable oxidizing agents such as performic acid can be stably present in the reaction system, and copper can be oxidized with good reproducibility.

Moreover, although the atmosphere which makes formic acid, copper, and an oxidizing agent react is normally performed under a normal pressure, it is performed also under the pressure of 50-200 kPa, for example. The reaction can be promoted by carrying out the reaction under pressure rather than normal pressure. The reaction rate can be adjusted by carrying out the reaction under a reduced pressure rather than the normal pressure.
In addition, reaction of formic acid, copper, and an oxidizing agent may put formic acid, copper, and an oxidizing agent simultaneously in a reaction container, and may put them in a reaction container in arbitrary orders.

  In such a method for producing copper formate, it is preferable to react copper and an oxidizing agent so that copper is oxidized to divalent copper in formic acid. As a result, zero-valent copper is reliably oxidized to divalent copper, and the copper reacts with formic acid, whereby copper formate can be obtained efficiently. Moreover, since the production of divalent copper by the reaction of copper and an oxidizing agent and the production of copper formate by the reaction of the divalent copper and formic acid are carried out in the same reaction system, it is extremely simple and quick. Copper formate can be obtained with good yield.

In this case, it is preferable to use an oxidizing agent having a strong oxidizing power as described above.
The method for producing copper formate according to the present invention includes, for example, a first step of producing formic acid by reacting formic acid and an oxidizing agent as shown in the following formula; and the formic acid and copper in formic acid. It can also carry out by the method of having made it react and the 2nd process of manufacturing copper formate. Thereby, after manufacturing a formic acid, since a formic acid and copper are made to react, copper formate can be obtained more reliably. Moreover, since the reaction liquid of a 1st process can be used for a 2nd process as it is, copper formate can be obtained with a sufficient yield simply by one pot. Furthermore, if the formic acid obtained in the first step is purified by distillation and used in the second step, copper formate with fewer impurities can be obtained. Moreover, since an inexpensive material is used, copper formate can be obtained at low cost.

The oxidizing agent in this case is not particularly limited as long as it can oxidize formic acid to performic acid. For example, the oxidizing agent having a strong oxidizing power and the oxidizing agent having a weak oxidizing power described above can be used.
The reaction time, reaction temperature, and reaction atmosphere in the first step and the second step are the same as the time, temperature, and atmosphere in which formic acid, copper, and the oxidizing agent are reacted as described above.
Since the copper formate obtained by the above method can be manufactured much more easily than before, the cost of various materials containing copper formate can be reduced.
Moreover, the copper formate obtained by this invention can be used for the manufacture of the copper particle mentioned later, the antiseptic | preservative for pools, the active ingredient of a mouthwash, the material of a metal ink, etc.

<Copper particles>
Next, although the manufacturing method of a copper particle is demonstrated, the copper particle manufactured by the manufacturing method of the copper particle of this invention is demonstrated before that.
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>
Next, the manufacturing method of a copper particle is demonstrated in detail.
The method for producing the copper particles 10 of the present invention includes, for example, a first step of obtaining copper formate by the method for producing copper formate,
By dissolving the copper formate in an aliphatic amine, the following general formula (1)

（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製造する第２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１０を製造する第３の工程とを有する方法である。これにより、安価な材料から簡便に銅粒子１０を得ることができる。また、各工程の生成物を単離することなく次工程に使用することができるため、極めて簡便かつ高収率に銅粒子１０を得ることができる。また、修飾剤として脂肪族アミンを用いているため、均一な粒径の銅粒子１０を得ることができる。

(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 second step of producing a copper formate complex represented by:
The copper particles 10 are produced 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. And a third step. Thereby, the copper particle 10 can be easily obtained from an inexpensive material. Moreover, since it can use for the following process, without isolating the product of each process, the copper particle 10 can be obtained very simply and with a high yield. Moreover, since the aliphatic amine is used as a modifier, the copper particle 10 of a uniform particle size can be obtained.

(First step)
A 1st process is a process of obtaining copper formate by the said manufacturing method of copper formate. Thereby, high-purity copper formate can be easily produced from an inexpensive material with a high yield. Note that the details of this step are as described above, and will be omitted.
(Second step)
In the second step, the following general formula (1) is obtained by dissolving the copper formate obtained in the first step in an aliphatic amine.

（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工程である。

In the formula, Cu is a divalent copper, and R ¹ and R ² are each an aliphatic hydrocarbon group which may have a substituent.

  In general, it is known that copper formate dissolves in water but does not dissolve in hydrophobic organic solvents. Therefore, when performing reaction using copper formate, hydrophilic solvents, such as water and alcohol, are 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 copper formate dissolves in an aliphatic amine that is hydrophobic. 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 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 very simply.
Here, the copper formate used in this step is obtained in the first step, and includes anhydrous copper formate and copper formate hydrate. When using anhydrous copper formate, it can be obtained by drying the copper formate obtained in the first step. 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 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, since reaction with an aliphatic amine advances reliably, the copper formate complex represented by General formula (1) can be obtained reliably.
On the other hand, the aliphatic amine used in this step 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, copper formate melt | dissolves in an aliphatic amine, and the copper formate complex represented by General formula (1) can be obtained simply. 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. 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.

Examples of such aliphatic amines include the following.
Examples of the primary amine include butylamine, hexylamine, octylamine, decylamine, tridecylamine, hexadecylamine, nonadecylamine, 1-dodecenylamine, 2-dodecynylamine and the like.
Examples of the secondary amine include dipropylamine, dibutylamine, diamylamine, dihexylamine, dioctylamine, didecylamine, didodecylamine, ditetradecylamine, and dihexadecylamine.

The amount of the aliphatic amine used in the reaction is preferably 2.2 to 20 equivalent mol and more preferably 4 to 10 equivalent mol with respect to 1 equivalent mol of copper formate. Thereby, since reaction with copper formate advances reliably, the copper formate complex represented by General formula (1) can be obtained reliably.
Such dissolution of copper formate in an aliphatic amine is performed, for example, by mixing them.
Specifically, in the case of an aliphatic amine having 4 to 11 carbon atoms, since it is liquid at room temperature (20 ° C.), it is mixed with copper formate as it is, and the copper formate complex represented by the general formula (1) Can be obtained very simply.

On the other hand, in the case of an aliphatic amine having 12 to 20 carbon atoms, it is a solid at room temperature (20 ° C.). Therefore, the aliphatic amine is heated and melted or heated and pressurized and melted and mixed with copper formate. The copper formate complex represented by (1) can be easily obtained.
The temperature at which the aliphatic amine is heated varies depending on the type of the 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 copper formate can be reliably dissolved.

In addition, the time for mixing the aliphatic amine and copper formate is preferably 0.5 to 2 hours, and more preferably 0.5 to 1 hour. Thereby, copper formate is reliably dissolved in the aliphatic amine, and the copper formate complex represented by the general formula (1) can be reliably obtained.
In order to crystallize the copper formate complex represented by the general formula (1) obtained by mixing 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.
As described above, since copper formate is dissolved in the aliphatic amine, the copper formate complex represented by the general formula (1) can be easily obtained with high yield.

Next, the copper formate complex obtained by such a method will be described in detail.
The copper formate complex obtained in the second step is a compound represented by the general formula (1). Thereby, since the aliphatic amine is coordinated to copper, the uniform copper particles 10 modified with the aliphatic amine 12 can be easily obtained by decomposing the copper formate complex represented by the general formula (1). Can get to.

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.

Specific amine ligands include the same amines as specifically described for the aliphatic amine.
Of these amine ligands, primary amine ligands are particularly preferable. Thereby, the copper formate which is a raw material melt | dissolves in an aliphatic primary amine, and the copper formate complex represented by General formula (1) can be obtained simply. 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.
As described above, according to this step, since copper formate is dissolved in the aliphatic amine, the copper formate complex represented by the general formula (1) can be easily obtained. Therefore, the production efficiency of the copper particles 10 can be improved.

(Third step)
In the third step, the formic acid is prepared so that divalent copper of the copper formate complex obtained in the second step is reduced to zero-valent copper and the formic acid ligand is oxidized to carbon dioxide. In this process, copper particles 10 are produced by decomposing the copper complex. Thereby, copper formate is decomposed | disassembled and the copper particle 10 can be obtained simply and with a high yield.

  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 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. Therefore, copper particles 10 having a uniform particle size can be obtained.

Here, the amount of the copper formate complex used in this step is preferably 0.1 to 50% by weight, more preferably 1 to 20% by weight, based on the total amount of the solution. By using copper formate in such a range, the decomposition reaction proceeds reliably, so that the copper particles 10 can be reliably obtained.
The organic solvent that dissolves the copper formate complex is not particularly limited as long as it can dissolve the copper formate complex. 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 and solvent of the copper formate complex represented by the general formula (1) are of the same type, the aliphatic amine 12 of the solvent binds to copper, so that one type of copper particles 10 is present. The modifier can be bound. 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.

  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 oxidizing the child to carbon dioxide.
As mentioned above, according to this process, since the copper particle 10 can be manufactured with sufficient yield only by decomposing | disassembling the copper formate complex represented by General formula (1), the production efficiency of the copper particle 10 is improved. Can be made.

As mentioned above, the manufacturing method of the copper particle 10 of this invention which has a 1st process-a 3rd process may perform each process continuously, may isolate a product for every process, and may advance to the next process.
By carrying out each step continuously, the reaction solution can be used as it is in the next step (because the reaction can be carried out in the same system), so that the copper particles 10 can be obtained very easily and with a high yield in one pot. it can.

Moreover, since each product is refine | purified by isolating a product for every process and then progressing to the next process, the highly purified copper particle 10 can be obtained.
Thus, since the manufacturing method of the copper particle 10 of this invention can obtain the copper particle 10 starting from an inexpensive raw material called copper formate, the production efficiency of the copper particle 10 can be further improved at low cost. Can do.

  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. Specific examples include a thin film transistor (TFT), a liquid crystal display (LCD), and an active matrix back plane (AMBP). Organic PCBs (printed circuit boards) have applications 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 the 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 on 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, there is a possibility that the liquid material 21 does not overlap 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 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 formate of this invention, the manufacturing method of a copper particle, 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 formate according to the present invention, one or two or more optional steps may be added.
Moreover, 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 formate (Example 1)
A flask was charged with 50 g (1.1 mol) of 98% formic acid and cooled to around 0 ° C. in an ice-containing water bath. Thereafter, 10.5 g of 20% aqueous hydrogen peroxide was added dropwise to the flask in an ice-containing water bath while stirring the formic acid solution. After dropping, stirring was continued for 1 hour while cooling. This produced formic acid.

Next, 3 g (0.05 mol, average particle size: about 3 μm) of 99.99% copper powder was added to the formic acid solution. The flask was removed from the ice-containing water bath, and stirring was continued for 8 hours. Meanwhile, a blue solution was formed and most of the copper powder was dissolved.
In order to remove a slight amount of insoluble matter, vacuum filtration was performed using a membrane (3 μm) made of Teflon (“Teflon” is a registered trademark, the same applies hereinafter). While the obtained filtrate was heated to 70 ° C. with a water bath, the solvent (formic acid / water) was removed with a rotary evaporator to obtain a blue copper formate powder. The obtained powder was vacuum dried in a vacuum thermostatic chamber at 55 ° C. for 8 hours. The yield was 93%.

(Example 2)
A flask was charged with 50 g (1.1 mol) of 98% formic acid and 3 g (0.05 mol, average particle size: about 3 μm) of 99.99% copper powder, and cooled to around 0 ° C. in an ice-containing water bath. Then, 10.5 g of 20% aqueous hydrogen peroxide was added dropwise while stirring the reaction solution. After dropping, stirring was continued for 1 hour while cooling.

After stirring for 1 hour, the flask was removed from the ice-containing water bath, and stirring was continued for 8 hours. Meanwhile, a blue solution was formed and most of the copper powder was dissolved. Thereby, formic acid and hydrogen peroxide reacted in the reaction system to form formic acid, and the formic acid reacted with copper to obtain copper formate.
Next, vacuum filtration was performed using a Teflon membrane (3 μm), and the solvent (formic acid / water) was removed with a rotary evaporator while heating the obtained filtrate at 70 ° C. with a water bath. The obtained blue powder was vacuum-dried in a vacuum thermostatic chamber at 55 ° C. for 8 hours. The yield was 90%.

(Example 3)
A flask was charged with 50 g (1.1 mol) of 98% formic acid and 3 g (0.05 mol, average particle size: about 3 μm) of 99.99% copper powder, and cooled to around 0 ° C. in an ice-containing water bath. Thereafter, while the reaction solution was stirred, ozone generated by the ozone generator was bubbled for 1 hour.

After 1 hour, the bubbling of ozone was stopped, the flask was removed from the ice-containing water bath, and stirring was continued for 8 hours. Meanwhile, a blue solution was formed and most of the copper powder was dissolved. Thereby, copper and ozone reacted in the reaction system to become divalent copper, and copper formate reacted with formic acid to obtain copper formate.
Next, vacuum filtration was performed using a Teflon membrane (3 μm), and the solvent (formic acid / water) was removed with a rotary evaporator while heating the obtained filtrate at 70 ° C. with a water bath. The obtained blue powder was vacuum-dried in a vacuum thermostatic chamber at 55 ° C. for 8 hours. The yield was 91%.
(Comparative Example 1)
In a flask, 50 g (1.1 mol) of 98% formic acid and 3 g (0.05 mol, average particle size: about 3 μm) of 99.99% copper powder were added and stirred. However, formic acid and copper did not react and copper formate was not obtained.

II. Evaluation of copper formate The copper formate 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 thermal decomposition behavior of copper formate equivalent to that of commercially available copper formate (manufactured by Sigma-Aldrich Japan, # 4040942) was obtained. That is, hydrate evaporation at about 90 ° C. and decomposition of copper formate at about 220 ° C. (copper formate → copper, carbon dioxide, carbon monoxide, hydrogen, water) were confirmed. The weight change at about 220 ° C. was 58.27%, which was almost the same as the theoretical value of anhydrous copper formate = 58.62%.
From the above, it was confirmed that copper formate was produced.
In addition, the copper formate obtained in Examples 2 and 3 was similarly evaluated, and it was confirmed that copper formate was produced.

III. Production of copper particles (Example 4)
<1> Production of copper formate complex 50 g (0.46 mol) of copper formate obtained in Example 1 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, 0.1 mol) 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 1 g (1.9 mmol) of the copper formate / dodecylamine complex obtained in <1> was dissolved in 20 g of dodecylamine and heated to 120 ° C. Thereby, copper particles were obtained with a yield of 95%.

(Example 5)
The copper formate obtained in Example 2 was used in the same manner as in Example 4 to obtain copper particles with a yield of 95%.
(Example 6)
The copper formate obtained in Example 3 was used in the same manner as in Example 4 to obtain copper particles with a yield of 95%.

(Example 7)
In Example 4, except having replaced the dodecylamine with hexylamine, it carried out similarly to Example 4 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 8)
In Example 4, except having replaced the dodecylamine with octylamine, it carried out like Example 4 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 9
In Example 4, it carried out like Example 4 except having replaced the dodecylamine with the decylamine, 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 10)
In Example 4, except having replaced the dodecylamine with the hexadecylamine, it carried out like Example 4 and obtained the copper particle with the yield of 91%.

(Example 11)
In Example 5, except that dodecylamine was replaced with hexylamine, it was performed in the same manner as in Example 7, and copper particles were obtained in the same yield.
(Example 12)
In Example 5, except changing dodecylamine to octylamine, it carried out similarly to Example 8 and obtained the copper particle with the same yield.

(Example 13)
In Example 5, except having replaced the dodecylamine with the decylamine, it carried out similarly to Example 9 and obtained the copper particle with the same yield.
(Example 14)
In Example 5, except having replaced the dodecylamine with the hexadecylamine, it carried out similarly to Example 10 and obtained the copper particle with the same yield.

(Example 15)
In Example 6, except having replaced the dodecylamine with hexylamine, it carried out similarly to Example 7 and obtained the copper particle with the same yield.
(Example 16)
In Example 6, except having replaced the dodecylamine with octylamine, it carried out like Example 8 and obtained the copper particle with the same yield.

(Example 17)
In Example 6, except having replaced dodecylamine with decylamine, it carried out similarly to Example 9 and obtained the copper particle with the same yield.
(Example 18)
In Example 6, except having replaced the dodecylamine with the hexadecylamine, it carried out similarly to Example 10 and obtained the copper particle with the same yield.

(Comparative Example 2)
50 g of the copper formate obtained in Example 1 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 (10 g), 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.

IV. Evaluation of Copper Particles The copper formate / dodecylamine complex obtained in Example 4 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. 6, 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 around 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 particles obtained in Example 4 was measured using a transmission electron microscope (JEM 2000EX manufactured by JEOL). As a result, the average particle size was 8 nm.
In addition, the copper particles of Examples 5 to 18 were performed in the same manner, and it was confirmed that the copper particles were produced with the same average particle diameter.

V. Production of wiring board (Example 19)
The copper particles produced in Example 4 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 20)
In Example 19, except having used the copper particle obtained in Example 7, it carried out similarly to Example 19 and obtained the wiring board.
(Example 21)
In Example 19, except having used the copper particle obtained in Example 8, it carried out similarly to Example 19 and obtained the wiring board.

(Example 22)
In Example 19, except having used the copper particle obtained in Example 9, it carried out similarly to Example 19 and obtained the wiring board.
(Example 23)
In Example 19, except having used the copper particle obtained in Example 10, it carried out similarly to Example 19 and obtained the wiring board.

VI. Evaluation of Wiring Substrate When the wiring substrate obtained in Example 19 was inspected, a 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.
In addition, the wiring boards of Examples 20 to 23 were also inspected in the same manner to confirm that they had the same quality.

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. It is a figure which shows the thermal-analysis result of the copper formate obtained in Example 1. The vertical axis on the left of the figure indicates the weight change (%) of copper formate, the vertical axis on the right of the figure indicates the weight change of the decomposed product versus the temperature derivative (% / ° C.), and the horizontal axis indicates the temperature (° C.). It is a figure which shows the thermal-analysis result of the copper particle obtained in Example 4. The left vertical axis in the figure represents the weight change (%) of the copper formate complex, the vertical axis in the figure represents the weight change of the copper particles versus the temperature differential (% / ° 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 (8)

A first step of reacting formic acid with an oxidizing agent to obtain formic acid;
A method for producing copper formate, comprising: a second step of obtaining copper formate by reacting said formic acid and copper. The method for producing copper formate according to claim 1 , wherein the copper is copper having a purity of 99% or more. The oxidizing agent is performic acid, hydrogen peroxide, a manufacturing method of formic acid copper according to claim 1 or 2, ozone or singlet oxygen. The method for producing copper formate according to any one of claims 1 to 3 , wherein the copper formate obtained by the method for producing copper formate according to any one of claims 1 to 3 is used for producing copper particles. A first step of obtaining a formic acid copper by the production method of formic acid copper according to any one of claims 1 to 4,
By dissolving the 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 second step of producing a copper formate complex represented by:
The copper formate is produced 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 a 3rd process, The manufacturing method of the copper particle characterized by the above-mentioned. The method for producing copper particles according to claim 5 , 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 6 , wherein the heating temperature of the copper formate complex is 70 to 200 ° C. A liquid material forming step of forming a liquid material copper particles produced by the production method of the copper particles are dispersed in a dispersion medium according to any one of claims 5 to 7,
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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