JP7263124B2 - Inkjet copper oxide ink and method for producing conductive substrate provided with conductive pattern using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a copper oxide ink for inkjet and a method for producing a conductive substrate provided with a conductive pattern using the same.

A circuit board has a structure in which conductive wiring is provided on a substrate. A method of manufacturing a circuit board is generally as follows. First, a photoresist is applied on a substrate to which a metal foil is attached. The photoresist is then exposed and developed to obtain the negative features of the desired circuit pattern.

Next, the portion of the metal foil not covered with the photoresist is removed by chemical etching to form a pattern. Thereby, a high-performance circuit board can be manufactured.

However, the conventional method has drawbacks such as a large number of steps, being complicated, and requiring a photoresist material.

On the other hand, direct wiring printing technology (hereinafter referred to as PE (printed electronics ), which is described as the law), is attracting attention. This technique has a small number of steps, does not require the use of a photoresist material, and has extremely high productivity.

Among direct printing methods, inkjet is a printing method in which ink is directly ejected from a nozzle onto a substrate. Due to its advantages such as simplicity and compact equipment, inkjet with high coating accuracy is desired. In addition, unlike other types of printing, there is no need to raise a plate, so it is suitable for small-lot, high-mix production.

Incidentally, commonly used inks include metal inks and metal pastes. The metal ink is a dispersion in which ultrafine metal particles having an average particle size of several nanometers to several tens of nanometers are dispersed in a dispersion medium. After the metal ink is applied and dried on the substrate, when it is heat-treated, it is sintered at a temperature lower than the melting point of the metal due to the melting point depression peculiar to the metal ultrafine particles, and a conductive metal film (hereinafter also referred to as a conductive film) is formed. ) can be formed. A metal film obtained using a metal ink has a thin film thickness and is close to a metal foil.

On the other hand, the metal paste is a dispersion in which micrometer-sized metal fine particles and a binder resin are dispersed in a dispersion medium. Due to the large size of the fine particles, they are usually supplied in a fairly viscous state to prevent settling. Therefore, it is suitable for screen printing suitable for highly viscous materials and application by a dispenser. A metal paste has a feature that a thick metal film can be formed because the size of the metal particles is large.

Copper is attracting attention as a metal to be used for the metal particles contained in such ink. In particular, as an alternative to ITO (indium tin oxide), which is widely used as an electrode material for projected capacitive touch panels, from the viewpoint of resistivity, ion (electrochemical) migration, performance as a conductor, price, reserves, etc. , copper is the most promising.

However, copper is easily oxidized in ultrafine particles of several tens of nanometers and requires anti-oxidation treatment. There is a problem that anti-oxidation treatment interferes with sintering.

In order to solve such problems, a copper thin film is formed by using ultrafine particles of copper oxide as a precursor and reducing the copper oxide to copper by energy such as heat and actinic rays in an appropriate atmosphere. has been proposed (see, for example, Patent Document 1).

Since the surface diffusion itself in the copper oxide ultrafine particles occurs at a temperature lower than 300° C., when the copper oxide is reduced to copper by energy under an appropriate atmosphere, the copper ultrafine particles are sintered to form a dense structure. Random chains are formed, and the whole becomes network-like, and the desired electrical conductivity is obtained.

WO2003/051562

A metal thin film obtained by a PE method using a metal ink (or metal paste) is required to have not only low resistivity but also little change over time. For example, with respect to silver paste, it is known that silver is susceptible to oxidation in the air, and oxidizes to increase the resistivity, so that the resistivity between silver particles deteriorates over time.

However, there is no prior art document that examines the stability of the resistivity of the metal film obtained by the PE method using the copper oxide ultrafine particles as a precursor disclosed in Patent Document 1.

In industrial use, the dispersion is also required to have excellent dispersion stability against changes over time at high concentrations.

The present invention has been made in view of the above points, and has high dispersion stability as an ink and can form a conductive film with low resistance on a substrate. An object of the present invention is to provide a method for manufacturing a flexible substrate.

In addition, inks suitable for inkjets are desired because inkjets do not require a plate, are simple and require compact equipment. Therefore, in addition to the above, an object of the present invention is to provide an inkjet copper oxide ink that is excellent in ejection performance for inkjet, has high coating accuracy, and can be continuously produced without clogging.

The inventors of the present invention have completed the present invention as a result of earnest research in order to solve the above problems.

That is, the inkjet copper oxide ink of one embodiment of the present invention contains copper oxide, a dispersant, a reducing agent, and an inkjet regulator as a solvent, and the content of the reducing agent is expressed by the following formula (1) , the content of the dispersant is in the range of the following formula (2), the solvent contains at least two kinds of the solvent having a boiling point of 100 ° C. or higher , and the inkjet modifier is graphene, graphene oxide, carbon nanotube, acrylic polymer, acrylic latex, silicone polymer, acrylic silicone latex, thiophene polymer, fluorine-containing organic compound, and polyethylene glycol; The content of the modifier is characterized by being within the range of the following formula (3).
0.0001 ≤ (mass of reducing agent/mass of copper oxide) ≤ 0.10 (1)
0.0050 ≤ (mass of dispersant/mass of copper oxide) ≤ 0.30 (2)
0.048 ≤ (mass of inkjet modifier/mass of copper oxide ink for inkjet) ≤ 0.20 (3)

With this configuration, by limiting the mass ranges of the reducing agent and the dispersing agent for copper oxide, the dispersion stability is improved and the resistance of the conductive film is effectively lowered. In addition, by limiting the solvent species, it is possible to form a high-definition L/S (line and space), and furthermore, there is no clogging of nozzles during inkjet printing, resulting in excellent continuous productivity. In addition, since baking treatment can be performed using plasma, light, or heat, organic substances in copper oxide are decomposed, baking of copper oxide is promoted, and a conductive film with low resistance can be formed.

In the inkjet copper oxide ink of one aspect of the present invention, the copper oxide is preferably cuprous oxide. This configuration facilitates the reduction of copper oxide and facilitates the sintering of the copper produced by the reduction.

In the copper oxide ink for inkjet according to one aspect of the present invention, the reducing agent includes hydrazine, hydrazine hydrate, sodium, carbon, potassium iodide, oxalic acid, iron (II) sulfide, sodium thiosulfate, ascorbic acid, and chloride. It preferably contains at least one selected from the group consisting of tin (II), diisobutylaluminum hydride, formic acid, sodium borohydride, and sulfite. This configuration improves the dispersion stability of the copper oxide and reduces the resistance of the conductive film.

In the copper oxide ink for inkjet according to one aspect of the present invention, the reducing agent is preferably hydrazine or hydrazine hydrate. This configuration further improves the dispersion stability of the copper oxide, contributes to the reduction of the copper oxide during firing, and further reduces the resistance of the conductive film.

In the copper oxide ink for inkjet according to one aspect of the present invention, the dispersant preferably has an acid value of 20 or more and 130 or less. Thereby, the dispersion stability of the copper oxide ink for inkjet can be improved.

In the copper oxide ink for inkjet according to one aspect of the present invention, the copper oxide ink for inkjet contains an inkjet modifier, the number average molecular weight of the inkjet modifier is 350 or more and 30000 or less, and the range of the above formula (3) is satisfied . . With this configuration, there is no clogging of nozzles during inkjet printing, and an effect of excellent continuous productivity can be obtained. In addition, when the baking treatment is performed using plasma, light, or heat, the organic matter in the copper oxide is decomposed, the baking of the copper oxide is promoted, and a uniform conductive film with low resistance can be formed .

A method for manufacturing a conductive substrate according to one aspect of the present invention includes forming a pattern on a substrate using the above copper oxide ink for inkjet, using an inkjet device, generating plasma in an atmosphere containing a reducing gas, The pattern is characterized by being subjected to baking treatment. This configuration enables low temperature firing. In addition, since the organic substances in the copper oxide are effectively decomposed, the baking of the copper oxide is further promoted, and a conductive substrate having a conductive film with a lower resistance can be produced.

In the method for producing a conductive substrate according to one aspect of the present invention, the copper oxide ink for inkjet described above is used, a pattern is formed on the substrate using an inkjet device, and then the pattern is subjected to heat or light irradiation treatment. characterized by performing With this configuration, the wavelength of light can be selected, so that the absorption wavelength of light of the copper oxide ink and the substrate can be taken into consideration. In addition, since the baking time by heat or light can be shortened, organic substances in the copper oxide are effectively decomposed while suppressing damage to the substrate, and a conductive substrate with a conductive film having low resistance can be manufactured. .

According to the present invention, as a copper oxide ink for inkjet, a conductive film having high dispersion stability and low resistance can be formed on a substrate.

It is a schematic diagram which shows the relationship between the copper oxide and phosphate ester salt which concern on this Embodiment. It is a cross-sectional schematic diagram which shows the conductive substrate which concerns on this Embodiment. It is explanatory drawing which shows each process of the manufacturing method of the conductive substrate which concerns on this Embodiment. FIG. 3 is a top view of a conductive substrate having a solder layer formed thereon according to the present embodiment;

Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail for the purpose of illustrating, but the present invention is not limited to the present embodiment. FIG. 1 is a schematic diagram showing the relationship between copper oxide and phosphate according to the present embodiment. FIG. 2 is a schematic cross-sectional view showing the conductive substrate according to this embodiment. FIG. 3 is an explanatory view showing each step of the method for manufacturing a conductive substrate according to this embodiment. FIG. 4 is a top view of a conductive substrate having a solder layer formed thereon according to this embodiment.

<Copper oxide ink for inkjet>
The copper oxide ink of the present embodiment is characterized by containing (1) copper oxide, (2) a dispersant, and (3) a reducing agent as a solvent. By containing a reducing agent in the copper oxide ink, the reduction of copper oxide to copper is promoted during firing, and the sintering of copper is promoted.

The content of the reducing agent satisfies the range of formula (1) below. When the mass ratio of the reducing agent is 0.0001 or more, the dispersion stability is improved and the resistance of the copper film is lowered. Moreover, when it is 0.1 or less, the long-term stability of the copper oxide ink is improved.
0.0001 ≤ (mass of reducing agent/mass of copper oxide) ≤ 0.10 (1)

In addition, reducing agents include hydrazine, hydrazine hydrate, sodium, carbon, potassium iodide, oxalic acid, iron (II) sulfide, sodium thiosulfate, ascorbic acid, tin (II) chloride, diisobutylaluminum hydride, formic acid, It preferably contains at least one selected from the group of sodium borohydride and sulfite. This improves the dispersion stability of the copper oxide and reduces the resistance of the conductive film.

Moreover, it is particularly preferable that the reducing agent is hydrazine or hydrazine hydrate. By using hydrazine or hydrazine hydrate as a reducing agent for the copper oxide ink, the dispersion stability of copper oxide is further improved, and it contributes to the reduction of copper oxide during firing, thereby further lowering the resistance of the conductive film.

Moreover, the content of the dispersant satisfies the range of the following formula (2). This suppresses the aggregation of copper oxide and improves the dispersion stability.
0.0050 ≤ (mass of dispersant/mass of copper oxide) ≤ 0.30 (2)

Moreover, the acid value of the dispersant is preferably 20 or more and 130 or less. This improves the dispersion stability of the copper oxide ink.

Also, the copper oxide is preferably cuprous oxide. This facilitates the reduction of copper oxide and facilitates sintering of the copper produced by the reduction.

In the inkjet copper oxide ink of the present embodiment, by limiting the range of the mass ratio of the reducing agent and the dispersing agent to the copper oxide, the dispersion stability is improved and the resistance of the conductive film is effectively lowered. Moreover, by limiting the range of the acid value of the dispersant, the dispersion stability is effectively improved. In addition, since baking treatment can be performed using plasma, light, or heat, organic substances in copper oxide are decomposed, baking of copper oxide is promoted, and a conductive film with low resistance can be formed. Therefore, it is possible to provide various types of copper wiring such as wiring for conducting electricity, heat dissipation, electromagnetic wave shielding, and circuits. In addition, in the present embodiment, it is possible to obtain an inkjet copper oxide ink that has high coating accuracy for inkjet, is free from clogging, and can be continuously produced. Inkjet does not require a plate and is simple and requires compact equipment. Therefore, by using the copper oxide ink of the present embodiment, the manufacturing process using the inkjet can be optimized, and the yield can be improved and the manufacturing cost can be reduced. It is possible to plan.

Next, the states of the copper oxide and the dispersant in the copper oxide ink for inkjet will be described with reference to FIG.

As shown in FIG. 1, in the copper oxide ink 1 for inkjet, a phosphoric acid ester salt 3, which is an example of a phosphorus-containing organic substance, is added as a dispersant around copper oxide 2, which is an example of copper oxide. It surrounds 3a facing inward and the ester salt 3b facing outward. Since the phosphate ester salt 3 exhibits electrical insulation, electrical conduction between adjacent copper oxides 2 is prevented. Further, the phosphate ester salt 3 suppresses aggregation of the copper oxide ink 1 due to the steric hindrance effect. The copper oxide 2 is dispersed in the solvent 4 .

The copper oxide 2 is semiconducting and conductive, but the copper oxide ink 1 exhibits electrical insulation because it is coated and dispersed with the phosphate ester salt 3 exhibiting electrical insulation.

By subjecting a coating film containing copper oxide and a phosphorus-containing organic substance (a coating film using copper oxide ink 1) to a baking treatment using plasma, light, or heat, copper oxide can be reduced to copper. Copper in which copper oxide has been reduced in this way is called reduced copper. Also, phosphorus-containing organic substances in the coating film are modified into phosphorus oxides. In the phosphorous oxide, the organic substance such as the above ester salt 3b (see FIG. 1) is decomposed by the heat of a laser or the like, and does not exhibit electrical insulation.

Further, as shown in FIG. 1, when copper oxide 2 is used, the copper oxide is changed into reduced copper and sintered by heat from a laser or the like, so that the adjacent copper oxides 2 are integrated. Thereby, a region having excellent electrical conductivity (hereinafter referred to as "conductive pattern") can be formed.

In the conductive pattern, elemental phosphorus remains in the reduced copper. The elemental phosphorus exists as at least one of elemental elemental phosphorus, phosphorus oxide, and phosphorus-containing organic matter. The remaining phosphorus element is segregated in the conductive pattern, and there is no risk of increasing the resistance of the conductive pattern.

[(1) Copper oxide]
In this embodiment, copper or copper oxide is used as one of the metal oxide components. As the copper oxide, cuprous oxide (Cu ₂ O) is preferable. This is because it is easy to reduce even among metal oxides, and it is easy to sinter by using fine particles. This is because it is advantageous.

Although the average secondary particle size of copper oxide is not particularly limited, it is preferably 500 nm or less, more preferably 200 nm or less, and even more preferably 80 nm or less. The average secondary particle size of copper oxide is preferably 5 nm or more, more preferably 10 nm or more, and still more preferably 15 nm or more. Here, the average secondary particle size is the average particle size of aggregates (secondary particles) formed by gathering a plurality of primary particles.

When the average secondary particle size is 500 nm or less, it is preferable because there is a tendency to easily form a fine pattern on the substrate. If the average secondary particle size is 5 nm or more, the long-term storage stability of the copper oxide ink is improved, which is preferable. The average secondary particle size of copper oxide can be measured by, for example, a transmission electron microscope or a scanning electron microscope.

In addition, the preferable range of the average primary particle size of the copper oxide is determined from the viewpoint of the denseness and electrical properties of the metal obtained by the reduction treatment, and furthermore, the firing conditions are determined according to the substrate in consideration of the use of the resin substrate. From the viewpoint of reducing damage, it is necessary to lower the temperature. Therefore, the average primary particle size is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 20 nm or less. When the average primary particle size is 100 nm or less, the input energy can be reduced so as not to damage the substrate in the baking treatment described later. Although the lower limit of the average primary particle diameter of cuprous oxide is not particularly limited, it is preferably 1 nm or more from the viewpoint of ease of handling. As a result, it is possible to suppress an increase in the amount of the dispersant used to maintain the dispersion stability due to the too small particle size, so that the firing treatment is facilitated. The average primary particle size can be measured with a transmission electron microscope or scanning electron microscope. The average particle size can be measured by the cumulant method using, for example, FPAR-1000 manufactured by Otsuka Electronics.

The copper oxide in the copper oxide ink is easily reduced by plasma treatment, heat treatment, and light treatment to become a metal, which is sintered to obtain conductivity. This contributes to lower resistance and improved strength. In the present embodiment, the average small diameter of the cuprous oxide particles does not affect the crack prevention effect of wire-like, dendritic, and scale-like copper particles, which will be described later.

As for cuprous oxide, a commercially available product may be used, or a synthesized product may be used. As a commercial product, there is a product with an average primary particle size of 5 to 50 nm manufactured by Rare Metals Research Laboratory. Synthetic methods include the following methods.
(1) Add water and a copper acetylacetonato complex to a polyol solvent, heat and dissolve the organocopper compound, then add water necessary for the reaction, and raise the temperature to the reduction temperature of the organocopper. A method of heating and reducing to
(2) A method of heating an organocopper compound (copper-N-nitrosophenylhydroxyamine complex) at a high temperature of about 300° C. in an inert atmosphere in the presence of a protective material such as hexadecylamine.
(3) A method of reducing a copper salt dissolved in an aqueous solution with hydrazine.
Among these, the method (3) is preferable because the operation is simple and cuprous oxide having a small average particle size can be obtained.

Since the resulting cuprous oxide is a soft agglomerate, a copper oxide dispersion is prepared by dispersing it in a solvent and used for printing and coating. After completion of the synthesis, the synthesis solution and cuprous oxide are separated, and a known method such as centrifugation may be used. Further, the resulting cuprous oxide is dispersed by adding a dispersant and a solvent, which will be described later, and stirring by a known method such as a homogenizer. Depending on the solvent, it may be difficult to disperse and the dispersion may be insufficient. In such a case, as an example, after dispersing using a solvent such as an alcohol that is easy to disperse, such as butanol, the desired solvent is substituted. concentration to a concentration of An example of the method is a method of repeating concentration with a UF membrane, dilution with a desired solvent, and concentration. The copper oxide dispersion thus obtained may be mixed with copper particles or the like by the method described later, and the copper oxide ink of the present embodiment can be obtained. This copper oxide ink is used for printing and coating.

[(2) Dispersant]
Next, the dispersant will be explained. Dispersants include, for example, phosphorus-containing organic substances. Phosphorus-containing organics may be adsorbed onto copper oxide, in which case the steric hindrance effect suppresses agglomeration. Also, the phosphorus-containing organic material is a material that exhibits electrical insulation in the insulating region. The phosphorus-containing organic substance may be a single molecule or a mixture of multiple types of molecules.

Although the number average molecular weight of the dispersant is not particularly limited, it is preferably from 300 to 30,000, for example. When it is 300 or more, the resulting copper oxide ink tends to be excellent in insulating properties and has increased dispersion stability. As for the structure, a phosphate ester of a high-molecular-weight copolymer having a group having an affinity for copper oxide is preferred. For example, the structure of chemical formula (1) is preferable because it adsorbs copper oxide, especially cuprous oxide, and has excellent adhesion to substrates.

It is preferable that the phosphorus-containing organic substance is easily decomposed or evaporated by light or heat. By using an organic substance that easily decomposes or evaporates by light or heat, it is possible to obtain a conductive pattern with a low resistivity by making it difficult for the residue of the organic substance to remain after baking.

Although the decomposition temperature of the phosphorus-containing organic substance is not limited, it is preferably 600° C. or lower, more preferably 400° C. or lower, and even more preferably 200° C. or lower. Although the boiling point of the phosphorus-containing organic substance is not limited, it is preferably 300° C. or lower, more preferably 200° C. or lower, and even more preferably 150° C. or lower.

Absorption characteristics of the phosphorus-containing organic material are not limited, but it is preferable that the material can absorb the light used for baking. For example, when light irradiation treatment (for example, light irradiation treatment with laser light) is performed for baking, a phosphorous-containing organic substance that absorbs light having an emission wavelength of, for example, 355 nm, 405 nm, 445 nm, 450 nm, 532 nm, 1056 nm, etc. It is preferable to use When the substrate is made of resin, wavelengths of 355 nm, 405 nm, 445 nm and 450 nm are particularly preferred.

As the dispersant, known ones can be used, for example, salts of long-chain polyaminoamides and polar acid esters, unsaturated polycarboxylic acid polyaminoamides, polycarboxylic acid salts of polyaminoamides, long-chain polyaminoamides and acid polymers Polymers having basic groups such as salts of In addition, acrylic polymers, acrylic copolymers, modified polyester acids, polyetherester acids, polyether carboxylic acids, alkylammonium salts, amine salts, and amidoamine salts of polymers such as polycarboxylic acids are also included. A commercially available dispersant can also be used as such a dispersant.

Examples of the commercially available products include DISPERBYK (registered trademark)-101, DISPERBYK-102, DISPERBYK-110, DISPERBYK-111, DISPERBYK-112, DISPERBYK-118, DISPERBYK-130, DISPERBYK-140, DISPERBYK-142, DISPERBYK- 145, DISPERBYK -160, DISPERBYK -161, DISPERBYK -162, DISPERBYK -163, DISPERBYK -2155, DISPERBYK -2155, DISPERBYK -2163, DISPERBYK -1264, DISPERBYK -1264, DISPERBYK -180, DISPERBYK -180, DISPERBYK ISPERBYK -2025, DISPERBYK -2163, DISPERBYK -2164, BYK-9076, BYK-9077, TERRA-204, TERRA-U (manufactured by BYK-Chemie), Floren DOPA-15B, Floren DOPA-15BHFS, Floren DOPA-22, Floren DOPA-33, Floren DOPA-44, Floren DOPA- 17HF, Floren TG-662C, Floren KTG-2400 (manufactured by Kyoeisha Chemical Co., Ltd.), ED-117, ED-118, ED-212, ED-213, ED-214, ED-216, ED-350, ED-360 (manufactured by Kusumoto Kasei Co., Ltd.), Plysurf (registered trademark) M208F, and Plysurf DBS (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.). These may be used alone, or may be used in combination.

The required amount of dispersant is proportional to the amount of copper oxide and adjusted in consideration of the required dispersion stability. The mass ratio of the dispersant contained in the copper oxide ink of the present embodiment (dispersant mass/copper oxide mass) is 0.0050 or more and 0.30 or less, preferably 0.050 or more and 0.25 or less, It is more preferably 0.10 or more and 0.23 or less. The amount of the dispersing agent affects the dispersion stability. If the amount is small, aggregation tends to occur, and if the amount is large, the dispersion stability tends to improve. However, when the content of the dispersant in the copper oxide ink of the present embodiment is 35% by mass or less, the influence of the residue derived from the dispersant can be suppressed in the conductive film obtained by firing, and the conductivity can be improved.

The acid value (mgKOH/g) of the dispersant is preferably 20 or more and 130 or less. More preferably 30 or more and 100 or less. If it falls within this range, it is preferable because it is excellent in dispersion stability. It is particularly effective in the case of copper oxide having a small average particle size. Specifically, "DISPERBYK-102" (acid value 101), "DISPERBYK-140" (acid value 73), "DISPERBYK-142" (acid value 46), "DISPERBYK-145" (acid value 76), "DISPERBYK-118" (acid value 36), "DISPERBYK-180 (acid value 94), and the like.

[(3) reducing agent]
Next, the reducing agent will be explained. As reducing agents, hydrazine, hydrazine hydrate, sodium, carbon, potassium iodide, oxalic acid, iron (II) sulfide, sodium thiosulfate, ascorbic acid, tin (II) chloride, diisobutylaluminum hydride, formic acid, hydrogen sodium borate, sulfite and the like. Hydrazine or hydrazine hydrate is most preferable as the reducing agent from the viewpoint that it contributes to reduction of copper oxide, particularly cuprous oxide, in firing, and a copper film with lower resistance can be produced. Moreover, by using hydrazine or hydrazine hydrate, the dispersion stability of the copper oxide ink can be maintained, and the resistance of the copper film can be lowered.

The required amount of reducing agent is proportional to the amount of copper oxide and is adjusted in consideration of the required reducing properties. The mass ratio of the reducing agent contained in the copper oxide ink of the present embodiment (mass of reducing agent/mass of copper oxide) is preferably 0.0001 or more and 0.10 or less, more preferably 0.0001 or more and 0.05 or less. It is more preferably 0.0001 or more and 0.03 or less. When the mass ratio of the reducing agent is 0.0001 or more, the dispersion stability is improved and the resistance of the copper film is lowered. Moreover, when it is 0.10 or less, the long-term stability of the copper oxide ink is improved.

[(4) Inkjet modifier]
Next, the inkjet modifier will be described. The inkjet copper oxide ink of this embodiment can further include an inkjet modifier. Examples of inkjet modifiers include graphene, graphene oxide, carbon nanotubes, acrylic polymers, acrylic latexes, silicone polymers, acrylic silicone latexes, thiophene polymers, fluorine-containing organic compounds, and polyethylene glycol. By including an inkjet adjusting agent in the copper oxide ink for inkjet, there is no clogging of nozzles during inkjet printing, and an effect of excellent continuous productivity can be obtained. In addition, lines can be clearly printed after ejection. When the baking treatment is performed using plasma, light, or heat, the organic matter in the copper oxide is decomposed, the baking of the copper oxide is promoted, and a uniform conductive film with low resistance can be formed.

The number average molecular weight of the inkjet regulator is preferably 350 or more and 30,000 or less, more preferably 500 or more and 20,000 or less, and still more preferably 1,000 or more and 15,000 or less. When it is 350 or more, clogging of nozzles during inkjet printing can be suppressed, and when it is 30000 or less, it is easy to mix with the copper oxide ink for inkjet.

The required amount of the inkjet modifier is proportional to the amount of the inkjet copper oxide ink, and is adjusted in consideration of the required inkjet printability. The mass ratio of the inkjet regulator contained in the copper oxide ink for inkjet of the present embodiment (mass of inkjet regulator/mass of copper oxide ink for inkjet) is preferably 0.010 or more and 0.40 or less, more preferably 0.010 or more and 0.40 or less. 020 or more and 0.30 or less, more preferably 0.050 or more and 0.20 or less. When the mass ratio of the inkjet regulator is 0.00010 or more, the ejection stability during inkjet printing is improved. Moreover, when it is 0.40 or less, the long-term stability of the copper oxide ink is improved.

[solvent]
The inkjet copper oxide ink of the present embodiment is characterized by containing at least two kinds of solvents (dispersion media) having a boiling point of 100° C. or higher in addition to the components described above. By containing at least two kinds of solvents (dispersion media) having a boiling point of 100° C. or higher, it is preferable to delay drying and eliminate clogging of the head. In addition, since it can be used to adjust the contact angle with the substrate, it is also good for high-definition printing. Furthermore, one type is used as a head clogging agent, and the other type is used as a reduction aid by heat or for adjusting the contact angle with the substrate, so it is preferable to mix the two types.

The solvent (dispersion medium) used in the present embodiment is selected from those capable of dissolving the dispersant from the viewpoint of dispersion. On the other hand, from the viewpoint of forming a conductive pattern using a copper oxide ink, the volatility of the solvent affects workability, so it is not suitable for forming a conductive pattern, for example, by printing or coating. there has to be Accordingly, the solvent may be selected from the following solvents in accordance with the dispersibility and workability of printing and coating.

Specific examples of the solvent include the following solvents. Propylene glycol monomethyl ether acetate, 3-methoxy-3-methyl-butyl acetate, ethoxyethyl propionate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol tertiary butyl ether, dipropylene glycol monomethyl ether, ethylene glycol butyl ether, ethylene glycol ethyl ether, ethylene glycol methyl ether, ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2-pentanediol, 2-methylpentane-2,4-diol, 2 ,5-hexanediol, 2,4-heptanediol, 2-ethylhexane-1,3-diol, diethylene glycol, hexanediol, octanediol, triethylene glycol, tri-1,2-propylene glycol, glycerol, ethylene glycol mono Hexyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, ethylene glycol monobutyl acetate, diethylene glycol monoethyl ether acetate, methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, 2-butanol, t- butanol, n-pentanol, i-pentanol, 2-methylbutanol, 2-pentanol, t-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, 1-hexanol, 2-hexanol, 2-ethylbutanol, 1-heptanol, 2-heptanol, 3-heptanol, n-octanol, 2-ethylhexanol, 2-octanol, n-nonyl alcohol, 2,6 dimethyl-4-heptanol, n-decanol, cyclohexanol , methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, diacetone alcohol and the like. Alcohols, glycols, glycol ethers, and glycol ester solvents can be used as solvents in addition to those specifically described above. These may be used alone, or may be used in combination, and are selected in consideration of the evaporativity, printing equipment, and solvent resistance of the substrate to be printed according to the printing method.

Addition of at least two kinds of solvent having a boiling point of 100° C. or higher is preferable in terms of high-definition printability and continuous production without clogging, especially in inkjet printing. Specifically, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol tertiary butyl ether, dipropylene glycol monomethyl ether, ethylene glycol butyl ether, ethylene glycol ethyl ether, ethylene glycol mono-normal-butyl ether, ethylene glycol methyl ether, ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2-pentanediol, 2-methylpentane-2,4-diol, 2,5 -hexanediol, 2,4-heptanediol, 2-ethylhexane-1,3-diol, diethylene glycol, hexanediol, octanediol, triethylene glycol, tri-1,2-propylene glycol, glycerol, ethylene glycol monohexyl ether , diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, ethylene glycol monobutyl acetate, diethylene glycol monoethyl ether acetate, n-butanol, i-butanol, 2-butanol, t-butanol, n-pentanol, i-pentanol, 2- Methylbutanol, 2-pentanol, t-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, 1-hexanol, 2-hexanol, 2-ethylbutanol, 1-heptanol, 2-heptanol, 3 -heptanol, n-octanol, 2-ethylhexanol, 2-octanol, n-nonyl alcohol, 2,6 dimethyl-4-heptanol, n-decanol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol , benzyl alcohol, decalin, tetralin, γ-butyrolactone, γ-valerolactone, N-methylpyrrolidone, toluene, xylene, N-ethyl-2-pyrrolidone, acetonitrile, water and the like.

As the solvent, monoalcohols having 10 or less carbon atoms are more preferable, and those having 8 or less carbon atoms are more preferable. Among the monoalcohols having 8 or less carbon atoms, n-butanol, i-butanol, sec-butanol, and t-butanol are more preferable because of their particularly suitable dispersibility, volatility and viscosity. These monoalcohols may be used singly or in combination. The number of carbon atoms in the monoalcohol is preferably 8 or less in order to suppress the deterioration of the dispersibility of copper oxide and to further stably disperse copper oxide through interaction with the dispersant. In addition, it is preferable to select 8 or less carbon atoms because the resistance value is also low.

Selection and combination of solvents are important for the inkjet copper oxide ink of the present embodiment. All of the above solvents have a boiling point of 100° C. or higher, and in the present embodiment, it is necessary to combine at least two of them.

In the combination of two solvents, for example, at least one is preferably ethylene glycol, diethylene glycol or propylene glycol, and another is n-butanol, i-butanol, 2-butanol, t-butanol or n-pentanol. , i-pentanol, 2-methylbutanol, 2-pentanol, t-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, 1-hexanol, 2-hexanol, 2-ethylbutanol, 1 -heptanol, 2-heptanol, 3-heptanol, n-octanol, 2-ethylhexanol, 2-octanol, n-nonyl alcohol, 2, 6 dimethyl-4-heptanol, n-decanol, cyclohexanol, methylcyclohexanol, 3 , 3,5-trimethylcyclohexanol, benzyl alcohol, decalin, tetralin, γ-butyrolactone, γ-valerolactone, N-methylpyrrolidone, toluene, xylene, N-ethyl-2-pyrrolidone, acetonitrile, and water. According to the combination of the above solvents, the copper oxide ink for inkjet provides a high-definition line width after printing, stable ink ejection, and excellent mass production.

<Preparation of copper oxide and copper oxide ink (dispersion) containing copper>
A dispersion containing cuprous oxide and copper particles, that is, a copper oxide ink for inkjet is prepared by mixing the copper oxide dispersion described above with copper fine particles and, if necessary, a solvent (dispersion medium) in a predetermined ratio. , For example, a mixer method, an ultrasonic method, a three-roll method, a two-roll method, an attritor, a homogenizer, a Banbury mixer, a paint shaker, a kneader, a ball mill, a sand mill, a rotation-revolution mixer, etc. can do. It is preferable to use a homogenizer as a method of dispersion treatment. In this embodiment, the dispersion liquid is diffused and dispersed by a known method such as a homogenizer in an inert atmosphere such as a nitrogen atmosphere.

Part of the solvent is contained in the already prepared copper oxide dispersion, so if the amount contained in this copper oxide dispersion is sufficient, there is no need to add it in this step, and the viscosity needs to be reduced. If necessary, it can be added in this step. Alternatively, it may be added after this step. The solvent may be the same as or different from that added during the preparation of the copper oxide dispersion described above.

In addition, organic binders, antioxidants, reducing agents, metal particles, and metal oxides may be added as necessary, and metals, metal oxides, metal salts, and metal complexes may be included as impurities.

In addition, wire-like, dendritic, and scale-like copper particles have a large anti-cracking effect, so they may be added alone or in combination with copper particles such as spherical, dice-like, or polyhedral particles, or a plurality of other metals, and the surfaces thereof may be oxidized. It may be coated with a material or other highly conductive metal such as silver.

In the case of adding one or more metal particles other than copper having a wire-like, dendritic, or scale-like shape, it has the same anti-cracking effect as copper particles with a similar shape, so one of the copper particles with a similar shape is used. Although it can be used in place of the part or in addition to copper particles of similar shape, it is necessary to consider migration, particle strength, resistance value, copper erosion, formation of intermetallic compounds, cost, and the like. Examples of metal particles other than copper include gold, silver, tin, zinc, nickel, platinum, bismuth, indium, and antimony.

As metal oxide particles, cuprous oxide can be replaced with silver oxide, cupric oxide, or the like, or can be used in addition. However, as with metal particles, migration, particle strength, resistance, copper erosion, formation of intermetallic compounds, cost, etc. must be considered. Addition of these metal particles and metal oxide particles can be used to adjust the sintering of the conductive film, the resistance, the strength of the conductor, the absorbance at the time of light firing, and the like. Even when these metal particles and metal oxide particles are added, cracks are sufficiently suppressed due to the presence of wire-like, dendritic and scale-like copper particles. These metal particles and metal oxide particles may be used alone or in combination of two or more types, and there is no limitation on the shape. For example, silver and silver oxide are expected to have effects such as resistance reduction and firing temperature reduction.

However, since silver is a noble metal, the cost is increased, and from the viewpoint of crack prevention, the amount of silver to be added is preferably within a range not exceeding that of the wire-like, dendrite-like, and scale-like copper particles. In addition, tin is inexpensive and has a low melting point, so it has the advantage of being easily sintered. However, the resistance tends to increase, and from the viewpoint of preventing cracks, the amount of tin to be added is preferably in a range not exceeding the amount of wire-like, dendritic, and scale-like copper particles and cuprous oxide. Cupric oxide works as a light absorber and a heat ray absorber in methods using light such as flash lamps and lasers or infrared rays. However, cupric oxide is more difficult to reduce than cuprous oxide, and from the viewpoint of preventing peeling from the substrate due to the large amount of gas generated during reduction, the amount of cupric oxide added should be less than that of cuprous oxide. is preferred.

In the present embodiment, even if metals other than copper, copper particles other than wire-like, dendritic, and scale-like particles, and metal oxides other than copper oxide are contained, the effect of preventing cracks and improving the resistance stability over time can be obtained. demonstrated. However, the amounts of metals other than copper, copper particles other than wire-like, dendritic, and scale-like particles, and metal oxides other than copper oxide should be less than the wire-like, dendritic, and scale-like copper particles and copper oxide. is preferred. In addition, the addition ratio of metals other than copper, copper particles other than wire-like, dendritic, and scale-like, and metal oxides other than copper oxide to the wire-like, dendrite-like, and scale-like copper particles and copper oxide is 50% or less. , more preferably 30% or less, and still more preferably 10% or less.

<Conductive substrate>
In the method for manufacturing a conductive substrate according to the present embodiment, the copper oxide ink according to the present embodiment is used, a pattern is formed on the substrate using an inkjet device, and the pattern is baked to form a conductive substrate on the substrate. It is characterized by forming a pattern.

[Structure of conductive substrate]
As shown in FIG. 2, the conductive substrate 10 includes a substrate 11 and a conductive pattern 13 containing reduced copper on a surface formed by the substrate 11 in a cross-sectional view. The conductive pattern 13 contains a phosphorus element. In the conductive pattern 13, the organic matter contained in the copper oxide ink is decomposed in the step of baking the copper oxide ink, so that the conductive pattern 13 has high solder wettability. Therefore, a solder layer can be easily formed on the surface of the conductive pattern 13 .

[Method of applying copper oxide ink for inkjet to substrate]
A coating method using copper oxide ink will be described. The inkjet copper oxide ink of the present embodiment literally exhibits a remarkable effect in printing using an inkjet. Here, the printing method of inkjet printing will be described.

In the present embodiment, the ink for inkjet refers to ink used in a printing mode (inkjet printing machine) in which the ink is formed into fine droplets and directly sprayed onto a medium to be printed.

From the above printing method, in order to eject the liquid from the head without clogging, the physical properties such as the particle size of the copper oxide, the dispersant for imparting dispersion stability, and the boiling point of the solvent should be optimized. is important, the ink of the present embodiment has a remarkable effect by satisfying the above requirements. Furthermore, by adding a reducing agent, the resistance of the wiring after reduction can be made low, which is preferable.

[substrate]
The substrate used in this embodiment mode is not particularly limited, and is composed of an inorganic material or an organic material.

Examples of inorganic materials include glasses such as soda lime glass, alkali-free glass, borosilicate glass, and quartz glass, and ceramic materials such as alumina.

Examples of organic materials include polymeric materials and paper. A resin film can be used as the polymer material, and polyimide (PI), polyethylene terephthalate (PET), polyether sulfone (PES), polyethylene naphthalate (PEN), polyester, polycarbonate (PC), polyvinyl alcohol (PVA) can be used. ), polyvinyl butyral (PVB), polyacetal (POM), polyarylate (PAR), polyamide (PA), polyamideimide (PAI), polyetherimide (PEI), polyphenylene ether (PPE), modified polyphenylene ether (m-PPE ), polyphenylene sulfide (PPS), polyetherketone (PEK), polyphthalamide (PPA), polyethernitrile (PEN), polybenzimidazole (PBI), polycarbodiimide, polysiloxane, polymethacrylamide, nitrile rubber, acrylic Rubber, polyethylene tetrafluoride, epoxy resin, phenolic resin, melamine resin, urea resin, polymethyl methacrylate resin (PMMA), polybutene, polypentene, ethylene-propylene copolymer, ethylene-butene-diene copolymer, polybutadiene, Polyisoprene, ethylene-propylene-diene copolymer, butyl rubber, polymethylpentene (PMP), polystyrene (PS), styrene-butadiene copolymer, polyethylene (PE), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF) ), polyetheretherketone (PEEK), phenol novolac, benzocyclobutene, polyvinylphenol, polychloropyrene, polyoxymethylene, polysulfone (PSF), polyphenylsulfone resin (PPSU), cycloolefin polymer (COP), acrylonitrile・Butadiene-styrene resin (ABS), acrylonitrile-styrene resin (AS), nylon resin (PA6, PA66), polybutyl terephthalate resin (PBT), polyethersulfone resin (PESU), polytetrafluoroethylene resin (PTFE), polychloro Examples include trifluoroethylene (PCTFE) and silicone resins. In particular, PI, PET and PEN are preferred from the viewpoint of flexibility and cost. The thickness of the substrate can be, for example, between 1 μm and 10 mm, preferably between 25 μm and 250 μm. If the thickness of the substrate is 250 μm or less, it is preferable because the electronic device to be produced can be made lightweight, space-saving, and flexible.

Examples of paper include fine paper, medium quality paper, coated paper, cardboard, cardboard, and other paper made from general pulp, and paper made from cellulose nanofiber. In the case of paper, a polymer material dissolved therein or a sol-gel material impregnated and cured can be used. Also, these materials may be used by laminating them together. For example, composite substrates such as paper phenol substrates, paper epoxy substrates, glass composite substrates, glass epoxy substrates, Teflon (registered trademark) substrates, alumina substrates, low temperature and low humidity co-fired ceramics (LTCC), silicon wafers etc. The board in the present embodiment means a board material for a circuit board sheet for forming a wiring pattern, or a housing material for a housing with wiring.

Since the printing method of inkjet printing is a method of directly ejecting ink, it is not required that the printing medium be flat. In other words, the surface shape of the print medium may be curved, slanted, a combination of multiple surfaces with different inclination angles, or a combination of a flat surface and a curved surface. It is not limited.

[Coating film containing copper oxide]
The coating contains, for example, hydrazine as a reducing agent along with copper oxide and a dispersing agent. By using hydrazine, it contributes to the reduction of copper oxide in firing, and a copper film with lower resistance can be produced.

<Products containing coating>
In the present embodiment, the product containing the coating film contains copper oxide, a dispersant, and a reducing agent, the content of the reducing agent is within the range of the following formula (1), and the content of the dispersing agent is the following formula: It is the range of (2).
0.0001 ≤ (mass of reducing agent/mass of copper oxide) ≤ 0.10 (1)
0.0050 ≤ (mass of dispersant/mass of copper oxide) ≤ 0.30 (2)

With this configuration, by limiting the mass range of the reducing agent and the dispersing agent for copper oxide, the dispersion stability of the copper oxide ink for inkjet is improved, and the resistance of the conductive film obtained by firing is effectively reduced. . In addition, since baking treatment can be performed using plasma, light, or heat, organic substances in copper oxide are decomposed, baking of copper oxide is promoted, and a conductive film with low resistance can be formed. In addition, in this embodiment, the coating film can further contain an inkjet adjusting agent. The preferred material, number average molecular weight, etc. of the inkjet regulator are as described above.

A product including a coating film here refers to, for example, the state of (g) in FIG. 3, which will be described later.

In this embodiment, the copper oxide of the coating film is preferably cuprous oxide. With this configuration, the copper oxide can be easily reduced, and the copper produced by the reduction can be easily sintered, so that the conductive film can be easily formed.

In the present embodiment, the reducing agent for the coating film is hydrazine, hydrazine hydrate, sodium, carbon, potassium iodide, oxalic acid, iron (II) sulfide, sodium thiosulfate, ascorbic acid, tin (II) chloride, hydrogen It preferably contains at least one selected from the group consisting of diisobutylaluminium chloride, formic acid, sodium borohydride, and sulfite. This configuration improves the dispersion stability of the copper oxide in the coating film and reduces the resistance of the conductive film.

In the present embodiment, the reducing agent for the coating film is preferably hydrazine or hydrazine hydrate. This configuration further improves the dispersion stability of the copper oxide in the coating film, contributes to the reduction of the copper oxide during firing, and further reduces the resistance of the conductive film.

The average secondary particle size of the fine particles containing copper oxide in the coating film is not particularly limited, but is preferably 500 nm or less, more preferably 200 nm or less, and even more preferably 80 nm or less. The average secondary particle size of the fine particles is preferably 5 nm or more, more preferably 10 nm or more, and even more preferably 15 nm or more. Here, the average secondary particle size is the average particle size of aggregates (secondary particles) formed by gathering a plurality of primary particles.

When the average secondary particle size is 500 nm or less, it is preferable because there is a tendency to easily form a fine pattern on the substrate. If the average secondary particle size is 5 nm or more, the long-term storage stability of the copper oxide ink is improved, which is preferable. The average secondary particle size of fine particles can be measured, for example, with a transmission electron microscope or a scanning electron microscope.

The average primary particle diameter of the primary particles constituting the secondary particles is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 20 nm or less. The average primary particle size is preferably 1 nm or more, more preferably 2 nm or more, and even more preferably 5 nm or more. When the average primary particle size is 100 nm or less, there is a tendency that the temperature for firing, which will be described later, can be lowered. The reason why such low-temperature firing is possible is thought to be that the smaller the particle diameter of the particles, the higher the surface energy and the lower the melting point. Further, if the average primary particle size is 1 nm or more, it is preferable because good dispersibility can be obtained. When wiring is formed on a substrate, the thickness is preferably 2 nm or more and 100 nm or less, more preferably 5 nm or more and 50 nm or less, from the viewpoint of adhesion to the substrate and low resistance. This tendency is remarkable when the substrate is made of resin. The average primary particle size can be measured with a transmission electron microscope or scanning electron microscope.

The mass ratio of the dispersant contained in the coating film of the present embodiment (dispersant mass/copper oxide mass) is 0.0050 or more and 0.30 or less, preferably 0.050 or more and 0.25 or less, It is more preferably 0.10 or more and 0.23 or less. The amount of the dispersing agent affects the dispersion stability. If the amount is small, aggregation tends to occur, and if the amount is large, the dispersion stability tends to improve. However, when the content of the dispersant in the coating film of the present embodiment is 35% by mass or less, the influence of the residue derived from the dispersant can be suppressed in the conductive film obtained by baking, and the conductivity can be improved.

The acid value (mgKOH/g) of the dispersant is preferably 20 or more and 130 or less, more preferably 30 or more and 100 or less. If it falls within this range, it is preferable because it is excellent in dispersion stability. It is particularly effective in the case of copper oxide having a small average particle size. Specific examples of dispersants include "DISPERBYK-102" (acid value 101), "DISPERBYK-140" (acid value 73), "DISPERBYK-142" (acid value 46), "DISPERBYK- 145” (acid value 76), “DISPERBYK-118” (acid value 36), “DISPERBYK-180 (acid value 94) and the like.

Next, the reducing agent in the coating film will be explained. As reducing agents, hydrazine, hydrazine hydrate, sodium, carbon, potassium iodide, oxalic acid, iron (II) sulfide, sodium thiosulfate, ascorbic acid, tin (II) chloride, diisobutylaluminum hydride, formic acid, hydrogen sodium borate, sulfite and the like. Hydrazine or hydrazine hydrate is most preferable as the reducing agent from the viewpoint that it contributes to the reduction of copper oxide, especially cuprous oxide, and enables the production of a copper film with lower resistance during firing. Moreover, by using hydrazine or hydrazine hydrate, the dispersion stability of the copper oxide ink can be maintained, and the resistance of the copper film can be lowered.

The mass ratio of the reducing agent contained in the coating film of the present embodiment (reducing agent mass/copper oxide mass) is preferably 0.0001 or more and 0.10 or less, more preferably 0.0001 or more and 0.05 or less, and further It is preferably 0.0001 or more and 0.03 or less. When the mass ratio of the reducing agent is 0.0001 or more, the dispersion stability is improved and the resistance of the copper film is lowered. On the other hand, when it is 0.10 or less, the long-term stability of the coating film is improved. The required amount of the reducing agent in the coating film is proportional to the amount of copper oxide, and is adjusted in consideration of the required reducibility.

The coating film of this embodiment can be produced on various materials and processed products such as film substrates, glass substrates, and molded products. Another resin layer may be overlaid on this film.

[Conductive film forming method]
In the method for producing a conductive film of the present embodiment, the copper oxide in the coating film is reduced to generate copper, which itself fuses and fuses with the copper particles added to the copper oxide ink for ink-jet, and is integrally formed. A conductive film (copper film) is formed by chemical conversion. This process is called firing. Therefore, there is no particular limitation as long as the method can form a conductive film by reduction and fusion of copper oxide and integration with copper particles. Firing in the method for producing a conductive film of this embodiment may be performed, for example, in a firing furnace, or may be performed using plasma, infrared rays, flash lamps, lasers, or the like alone or in combination.

A method for manufacturing a conductive substrate according to the present embodiment will be described more specifically with reference to FIG. In FIG. 3A, for example, copper acetate is dissolved in a mixed solvent of water and propylene glycol (PG), hydrazine is added as a reducing agent, and the mixture is stirred. The content of the reducing agent is adjusted so that it falls within the range of the following formula (1).
0.0001 ≤ (mass of reducing agent/mass of copper oxide) ≤ 0.10 (1)

Next, in (b) and (c) of FIG. 3, centrifugation was performed to separate the supernatant and the precipitate. Next, in (d) of FIG. 3, a dispersant and a solvent are added to the obtained precipitate to disperse it. At this time, at least two kinds of solvents having a boiling point of 100° C. or higher are contained. Also, the content of the dispersant is adjusted so as to fall within the range of the following formula (2).
0.0050 ≤ (mass of dispersant/mass of copper oxide) ≤ 0.30 (2)

As a result, a copper oxide ink (dispersion) containing copper oxide is obtained as shown in FIG. 3(e).

In FIG. 3(f), for example, a copper oxide ink is printed on a substrate made of PET in a desired pattern using an inkjet device, and a coating film containing copper oxide and a phosphorus-containing organic substance (FIG. 3(g) medium, described as "Cu ₂ O-containing coating film").

Next, in FIG. 3(h), the pattern on the substrate is subjected to heat irradiation, light irradiation, or plasma irradiation to bake the pattern and convert copper oxide into copper (in FIG. 3(i), " Cu”). As a result, in (i) of FIG. 3, a conductive substrate is obtained in which a conductive pattern (Cu layer) containing copper and phosphorus elements is formed on the substrate. Alternatively, a product having the resulting conductive pattern can be obtained by subjecting the product including the coating film to the above-described baking treatment.

In this way, by performing firing by plasma irradiation, heat irradiation, or light irradiation, the organic matter contained in the copper oxide ink is effectively decomposed. to be higher.

As shown in FIG. 3, by forming a conductive pattern, wiring with a line width of 0.1 μm or more and 1 cm or less can be formed, and can be used as copper wiring or an antenna. Taking advantage of the nanoparticles of copper oxide particles, the line width of the copper wiring is more preferably 0.1 μm or more and 500 μm or less, further preferably 0.1 μm or more and 100 μm or less, and 0.1 μm or more. , 5 μm or less is even more preferred. If the line width is 5 μm or less, the wiring cannot be visually recognized, which is preferable from the viewpoint of design.

[Formation of solder layer on conductive film]
In the conductive substrate produced using the copper oxide ink for inkjet according to the present embodiment, the dispersant and solvent that deteriorate the solderability are decomposed in the baking process, so that the conductive pattern is covered. There is an advantage that molten solder is easily applied when soldering a joint (for example, an electronic component, etc.).

In the present embodiment, electronic components include active components such as semiconductors, integrated circuits, diodes, and liquid crystal displays, passive components such as resistors and capacitors, and mechanical components such as connectors, switches, electric wires, heat sinks, and antennas. , at least one.

Moreover, it is preferable that the solder layer is formed on the conductive pattern by a reflow method. In the reflow method, solder paste (cream solder) is first applied to a part of the conductive pattern formed in FIG. 3(i), for example, the surface of the land. Solder paste is applied, for example, by contact printing using a metal mask and a metal squeegee. A solder layer is thereby formed on a portion of the surface of the conductive pattern. That is, after the step of FIG. 3(i), a conductive substrate having a solder layer formed on a part of the surface of the conductive pattern is obtained. The area of the part of the surface of the conductive pattern on which the solder layer is formed is not particularly limited as long as the conductive pattern and the electronic component can be bonded.

[Joining electronic components]
Next, the electronic component is placed on the conductive substrate so that the part to be joined of the electronic component is in contact with part of the applied solder paste (solder layer). After that, the conductive substrate on which the electronic component is placed is passed through a reflow furnace to heat, and a part of the conductive pattern area (land, etc.) and the part to be joined of the electronic component are soldered. FIG. 4 is a top view of a conductive substrate having a solder layer formed thereon according to this embodiment.

As shown in FIG. 4, a conductive pattern B formed by baking copper oxide ink is formed on a substrate 11 having flexibility. A solder layer 20 is formed on the surface of the conductive pattern B. As shown in FIG. The conductive pattern B and the conductor 90 are properly soldered by the solder layer 20 , and the conductive pattern B and the electronic component 91 are appropriately connected via the conductor 90 .

According to the method for manufacturing a conductive substrate and a product according to the present embodiment, since the copper oxide ink is baked to form the conductive pattern, the organic matter contained in the copper oxide ink is decomposed. The wettability of the solder becomes high in the conductive pattern, and a solder layer can be easily formed on the surface of the conductive pattern. Therefore, soldering of electronic parts becomes possible. As a result, it is possible to prevent defects from occurring in the solder layer that joins the conductive pattern and the part to be joined of the electronic component, and manufacture a conductive substrate to which the electronic component is soldered with a high yield.

The method of firing treatment is not particularly limited as long as it can form a conductive film exhibiting the effects of the present invention, but specific examples include methods using an incinerator, a plasma firing method, a light firing method, and the like. .

[Firing furnace]
In the method of firing in a firing furnace that is susceptible to oxygen, it is preferable to treat the coating film of the copper oxide ink in a non-oxidizing atmosphere. If the copper oxide ink is difficult to be reduced only by the organic components contained in the copper oxide ink, it is preferable to bake the ink in a reducing atmosphere. A non-oxidizing atmosphere is an atmosphere that does not contain an oxidizing gas such as oxygen, and is, for example, an atmosphere filled with an inert gas such as nitrogen, argon, helium, or neon. A reducing atmosphere refers to an atmosphere in which a reducing gas such as hydrogen or carbon monoxide is present, but it may be used in combination with an inert gas. The coating film of the copper oxide ink may be baked in a closed system filled with these gases in a baking furnace or while the gas is continuously flowed. Also, the firing may be performed in a pressurized atmosphere or in a reduced pressure atmosphere.

[Plasma firing method]
Compared to the method using a baking furnace, the plasma method of this embodiment enables treatment at a lower temperature, and is one of the better methods as a baking method when using a resin film with low heat resistance as a base material. is. In addition, plasma can be used to remove organic substances and oxide films from the surface of the pattern, so there is the advantage that good solderability can be ensured. Specifically, a reducing gas or a mixed gas of a reducing gas and an inert gas is flowed into the chamber, plasma is generated by microwaves, and the active species generated thereby are subjected to the heating required for reduction or sintering. It is a method of obtaining a conductive film by using it as a source and also for decomposing organic matter contained in a dispersant or the like.

In particular, the active species are often deactivated in the metal portion, the metal portion is selectively heated, and the temperature of the substrate itself is difficult to rise. The copper oxide ink contains copper as a metal, and the copper oxide changes to copper as the baking progresses, thus promoting heating of only the pattern portion. Also, if organic matter such as a dispersant or a binder component remains in the conductive pattern, it hinders sintering and tends to increase the resistance, but the plasma method is highly effective in removing the organic matter in the conductive pattern. Since the plasma method can remove organic substances and oxide films on the surface of the coating film, it also has the advantage of effectively improving the solderability of the conductive pattern.

Hydrogen or the like can be used as the reducing gas component, and nitrogen, helium, argon or the like can be used as the inert gas component. These may be used alone or as a mixture of a reducing gas component and an inert gas component in an arbitrary ratio. Moreover, two or more kinds of inert gas components may be mixed and used.

In the plasma firing method, it is possible to adjust the power of the microwave input, the flow rate of the introduced gas, the internal pressure of the chamber, the distance from the plasma generation source to the sample to be processed, the temperature of the sample to be processed, and the processing time. can be changed. Therefore, if the above adjustment items are optimized, not only inorganic material substrates but also organic material thermosetting resin films, paper, and thermoplastic resin films with low heat resistance such as PET and PEN can be used as substrates. , a conductive film with low resistance can be obtained. However, since the optimum conditions differ depending on the structure of the apparatus and the type of sample, adjustments should be made according to the situation.

[Light firing method]
A flash light method using a discharge tube such as xenon as a light source, or a laser light method can be applied to the photobaking method of the present embodiment. In these methods, high-intensity light is exposed for a short period of time, and the copper oxide ink coated on the substrate is raised to a high temperature in a short period of time and baked. and a method of decomposing an organic component to form a conductive film. Since the baking time is very short, the method causes little damage to the substrate, and can be applied to resin film substrates with low heat resistance.

The flash light method uses a xenon discharge tube to instantaneously discharge the electric charge stored in the capacitor, generating a large amount of pulsed light and irradiating the copper oxide ink formed on the substrate to oxidize it. This method instantly heats copper to a high temperature to change it into a conductive film. The amount of exposure can be adjusted by light intensity, light emission time, light irradiation interval, and number of times. A conductive pattern can be formed.

Although the light source is different, a similar effect can be obtained by using a laser light source. In the case of laser, in addition to the adjustment items of the flash light method, there is a degree of freedom in wavelength selection, and it is also possible to consider the light absorption wavelength of the patterned inkjet copper oxide ink and the absorption wavelength of the substrate. . In addition, it is characterized in that exposure by beam scanning is possible, and adjustment of the exposure range is easy, such as selection of exposure over the entire surface of the substrate or partial exposure. YAG (yttrium aluminum garnet), YVO (yttrium vanadate), Yb (ytterbium), semiconductor lasers (GaAs, GaAlAs, GaInAs), carbon dioxide gas, etc. can be used as the type of laser. Harmonics may be extracted and used as needed.

In particular, when laser light is used, the emission wavelength is preferably 300 nm or more and 1500 nm or less. For example, 355 nm, 405 nm, 445 nm, 450 nm, 532 nm, 1056 nm, etc. are preferable. When the substrate and the housing are made of resin, laser wavelengths of 355 nm, 405 nm, 445 nm and 450 nm are particularly preferred.

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples and Comparative Examples.

[Method for quantifying hydrazine]
Hydrazine was quantified by the standard addition method.

33 μg of hydrazine, 33 μg of surrogate substance (hydrazine ¹⁵ N ₂ H ₄ ), and 1 ml of benzaldehyde 1% acetonitrile solution were added to 50 μL of sample (copper nanoink). Finally, 20 μL of phosphoric acid was added, and 4 hours later, GC/MS measurement was performed.

Similarly, 66 μg of hydrazine, 33 μg of surrogate substance (hydrazine ¹⁵ N ₂ H ₄ ), and 1 ml of benzaldehyde 1% acetonitrile solution were added to 50 μL of sample (copper nanoink). Finally, 20 μL of phosphoric acid was added, and 4 hours later, GC/MS measurement was performed.

Similarly, 133 μg of hydrazine, 33 μg of surrogate substance (hydrazine ¹⁵ N ₂ H ₄ ), and 1 ml of benzaldehyde 1% acetonitrile solution were added to 50 μL of sample (copper nanoink). Finally, 20 μL of phosphoric acid was added, and 4 hours later, GC/MS measurement was performed.

Finally, to 50 μL of sample (copper nanoink), no hydrazine was added, 33 μg of surrogate substance (Hydrazine ¹⁵ N ₂ H ₄ ), 1 mL of benzaldehyde 1% acetonitrile solution were added, finally 20 μL of phosphoric acid was added, and after 4 hours, GC /MS measurements were performed.

A peak area value of hydrazine was obtained from the chromatogram at m/z=207 from the 4-point GC/MS measurement. Next, the surrogate peak area value was obtained from the mass chromatogram at m/z=209. The weight of added hydrazine/weight of added surrogate substance is plotted on the x-axis, and the peak area value of hydrazine/peak area value of surrogate substance is plotted on the y-axis to obtain a calibration curve according to the standard addition method.

The Y-intercept value obtained from the calibration curve was divided by the weight of added hydrazine/weight of added surrogate substance to obtain the weight of hydrazine.

[Particle size measurement]
The average particle size of the copper oxide ink was measured by the cumulant method using an Otsuka Electronics FPAR-1000.

[Dispersion stability]
Regarding the dispersion stability of the copper oxide ink, the period until the particle diameter immediately after adjustment doubles after storage of the copper oxide ink at -17 ° C. is A: 3 months or more, B: 1 month or more and 3 months. Less than C: Less than 1 month.
[Inkjet printability]
The inkjet printability of the copper oxide ink was evaluated as follows.
S: No discontinuity or fading of the line was observed, and no discontinuity or fading of the line was observed even after reprinting after 1 hour. A: No discontinuity or fading of the line was observed. : The line is discontinuous or blurred, and the droplets land on a place other than the line, so the line cannot be drawn.

(Example 1)
Dissolve 806 g of copper (II) acetate monohydrate (manufactured by Wako Pure Chemical) in a mixed solvent of 7560 g of water and 3494 g of 1,2-propylene glycol (manufactured by Wako Pure Chemical) and add hydrazine monohydrate (manufactured by Wako Pure Chemical). ) was added and stirred. After that, it was separated into a supernatant and a precipitate by centrifugation.

To 390 g of the obtained precipitate, 54.8 g of DISPERBYK-145 (manufactured by BYK-Chemie) (hereinafter abbreviated as BYK145) and 490 g of diethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.) were added as dispersants, and a homogenizer was added under a nitrogen atmosphere. distributed using

Then, concentration by a UF membrane module and dilution by diethylene glycol were repeated to obtain a cuprous oxide dispersion containing cuprous oxide having an average secondary particle size of 20 nm. γ-butyrolactone (manufactured by Wako Pure Chemical Industries, Ltd.) was added to the obtained cuprous oxide dispersion, and the following composition ratio was adjusted to obtain an inkjet copper oxide ink (1).
_Cu2O /DEG/BYK145/γ-butyrolactone/hydrazine = 20/36/4/39.7/0.3 (unit: % by mass).

The copper oxide ink was well dispersed. The content of cuprous oxide in 100 g was 20 g, and the particle size was 21 nm. The amount of hydrazine was 2700 ppm. Moreover, the dispersant content was 4 g.

In Example 1, the acid number of the dispersant was 76. The reducing agent mass/copper oxide mass was 0.014, the dispersant mass/copper oxide mass was 0.2, and the dispersion stability was A.

The solvents contained in the copper oxide ink in Example 1 were diethylene glycol and γ-butyrolactone, and the boiling point of diethylene glycol was about 245°C and the boiling point of γ-butyrolactone was about 200°C.

A DMC-11601 cartridge (manufactured by Fujifilm) was filled with the obtained copper oxide ink, and inkjet printing was performed using a Dimatrix material printer (manufactured by Fujifilm) under the conditions of line: 20 μm and space: 20 μm. The inkjet printability was B.

[Resistance measurement]
The pattern obtained by inkjet was heated and baked in a plasma baking apparatus at 1.5 kw for 420 seconds to reduce it, thereby producing a copper film. The volume resistivity of the conductive film was measured using a Mitsubishi Chemical low resistivity meter Lorestar GP. As a result, it was 20 μΩcm.

(Example 2)
Dissolve 806 g of copper (II) acetate monohydrate (manufactured by Wako Pure Chemical) in a mixed solvent of 7560 g of water and 3494 g of 1,2-propylene glycol (manufactured by Wako Pure Chemical) and add hydrazine monohydrate (manufactured by Wako Pure Chemical). ) was added and stirred. After that, it was separated into a supernatant and a precipitate by centrifugation.

82.2 g of BYK145 and 490 g of diethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.) were added as dispersants to 390 g of the obtained precipitate, and dispersed using a homogenizer under a nitrogen atmosphere.

Then, concentration by the UF membrane module and dilution by diethylene glycol were repeated to obtain a cuprous oxide dispersion (copper oxide ink). γ-butyrolactone (manufactured by Wako Pure Chemical Industries, Ltd.) was added to the obtained cuprous oxide dispersion, and the following composition ratio was adjusted to obtain an inkjet copper oxide ink (2).
_Cu2O /DEG/BYK145/γ-butyrolactone/hydrazine = 20/36/6/37.7/0.3 (unit is % by mass).

The inkjet copper oxide ink (2) was well dispersed. The content of cuprous oxide in 100 g was 20 g, and the particle size was 32 nm. The amount of hydrazine was 2800 ppm. Moreover, the dispersant content was 6 g.

In Example 2, the acid number of the dispersant was 76. The reducing agent mass/copper oxide mass was 0.014, the dispersant mass/copper oxide mass was 0.3, and the dispersion stability was B.

Using the obtained copper oxide ink for inkjet (2), inkjet printing was performed under the same conditions as in Example 1, and the copper film was prepared by heating and baking under the same conditions as in Example 1 for reduction. The inkjet printability was B. The volume resistivity of the conductive film was 25 μΩcm.

(Example 3)
Dissolve 806 g of copper (II) acetate monohydrate (manufactured by Wako Pure Chemical) in a mixed solvent of 7560 g of water and 3494 g of 1,2-propylene glycol (manufactured by Wako Pure Chemical) and add hydrazine monohydrate (manufactured by Wako Pure Chemical). ) was added and stirred. After that, it was separated into a supernatant and a precipitate by centrifugation.

68.5 g of BYK145 and 490 g of diethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.) were added as dispersants to 390 g of the obtained precipitate, and dispersed using a homogenizer under a nitrogen atmosphere.

Then, concentration by the UF membrane module and dilution by diethylene glycol were repeated to obtain a cuprous oxide dispersion (copper oxide ink). γ-Butyrolactone (manufactured by Wako Pure Chemical Industries, Ltd.) was added to the obtained cuprous oxide dispersion, and the following composition ratio was adjusted to obtain an inkjet copper oxide ink (3).
_Cu2O /DEG/BYK145/γ-butyrolactone/hydrazine = 20/36/5/38.7/0.3 (unit is % by mass).

The inkjet copper oxide ink (3) was well dispersed. The content of cuprous oxide in 100 g was 20 g, and the particle size was 25 nm. The amount of hydrazine was 2700 ppm. Moreover, the content of the dispersant was 5 g.

In Example 3, the acid number of the dispersant was 76. The reducing agent mass/copper oxide mass was 0.014, the dispersant mass/copper oxide mass was 0.25, and the dispersion stability was A.

Using the obtained copper oxide ink for inkjet (3), inkjet printing was performed under the same conditions as in Example 1, and heating and baking were performed under the same conditions as in Example 1 for reduction to form a copper film. The inkjet printability was B. The volume resistivity of the conductive film was 21 μΩcm.

(Example 4)
Dissolve 806 g of copper (II) acetate monohydrate (manufactured by Wako Pure Chemical) in a mixed solvent of 7560 g of water and 3494 g of 1,2-propylene glycol (manufactured by Wako Pure Chemical) and add hydrazine monohydrate (manufactured by Wako Pure Chemical). ) was added and stirred. After that, it was separated into a supernatant and a precipitate by centrifugation.

1.37 g of BYK145 and 490 g of diethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.) were added as dispersants to 390 g of the obtained precipitate, and dispersed using a homogenizer under a nitrogen atmosphere.

Then, concentration by the UF membrane module and dilution by diethylene glycol were repeated to obtain a cuprous oxide dispersion (copper oxide ink). γ-butyrolactone (manufactured by Wako Pure Chemical Industries, Ltd.) was added to the obtained cuprous oxide dispersion, and the following composition ratio was adjusted to obtain an inkjet copper oxide ink (4).
Cu2O/DEG/BYK145/γ-butyrolactone/hydrazine = 20/36/0.1/43.6/0.3 (unit: % by mass).

The inkjet copper oxide ink (4) was well dispersed. The content of cuprous oxide in 100 g was 20 g, and the particle size was 32 nm. The amount of hydrazine was 2800 ppm. Moreover, the dispersant content was 0.1 g.

In Example 4, the acid number of the dispersant was 76. The reducing agent mass/copper oxide mass was 0.014, the dispersant mass/copper oxide mass was 0.005, and the dispersion stability was B.

Using the obtained copper oxide ink for inkjet (4), inkjet printing was performed under the same conditions as in Example 1, and heating and baking were performed under the same conditions as in Example 1 for reduction to form a copper film. The inkjet printability was B. The volume resistivity of the conductive film was 19 μΩcm.

(Example 5)
Dissolve 806 g of copper (II) acetate monohydrate (manufactured by Wako Pure Chemical) in a mixed solvent of 7560 g of water and 3494 g of 1,2-propylene glycol (manufactured by Wako Pure Chemical) and add hydrazine monohydrate (manufactured by Wako Pure Chemical). ) was added and stirred. After that, it was separated into a supernatant and a precipitate by centrifugation.

13.7 g of BYK145 and 490 g of diethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.) were added as dispersants to 390 g of the obtained precipitate, and dispersed using a homogenizer under a nitrogen atmosphere.

Then, concentration by the UF membrane module and dilution by diethylene glycol were repeated to obtain a cuprous oxide dispersion (copper oxide ink). γ-butyrolactone (manufactured by Wako Pure Chemical Industries, Ltd.) was added to the obtained cuprous oxide dispersion, and the following composition ratio was adjusted to obtain an inkjet copper oxide ink (5).
Cu2O/DEG/BYK145/γ-butyrolactone/hydrazine = 20/36/1/42.7/0.3 (unit: % by mass).

The inkjet copper oxide ink (5) was well dispersed. The content of cuprous oxide in 100 g was 20 g, and the particle size was 26 nm. The amount of hydrazine was 2800 ppm. Moreover, the dispersant content was 1 g.

In Example 5, the acid number of the dispersant was 76. The reducing agent mass/copper oxide mass was 0.014, the dispersant mass/copper oxide mass was 0.05, and the dispersion stability was A.

Using the obtained ink jet copper oxide ink (5), ink jet printing was performed under the same conditions as in Example 1, and the ink was heated and baked under the same conditions as in Example 1 for reduction to form a copper film. The inkjet printability was B. The volume resistivity of the conductive film was 19 μΩcm.

(Example 6)
Dissolve 806 g of copper (II) acetate monohydrate (manufactured by Wako Pure Chemical) in a mixed solvent of 7560 g of water and 3494 g of 1,2-propylene glycol (manufactured by Wako Pure Chemical) and add hydrazine monohydrate (manufactured by Wako Pure Chemical). ) was added and stirred. After that, it was separated into a supernatant and a precipitate by centrifugation.

27.4 g of BYK145 and 490 g of diethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.) were added as dispersants to 390 g of the obtained precipitate, and dispersed using a homogenizer under a nitrogen atmosphere.

Then, concentration by the UF membrane module and dilution by diethylene glycol were repeated to obtain a cuprous oxide dispersion (copper oxide ink). γ-butyrolactone (manufactured by Wako Pure Chemical Industries, Ltd.) was added to the obtained cuprous oxide dispersion, and the following composition ratio was adjusted to obtain an inkjet copper oxide ink (6).
Cu2O/DEG/BYK145/γ-butyrolactone/hydrazine = 20/36/2/41.7/0.3 (unit: % by mass).

The inkjet copper oxide ink (6) was well dispersed. The content of cuprous oxide in 100 g was 20 g, and the particle size was 22 nm. The amount of hydrazine was 2800 ppm. Moreover, the dispersant content was 2 g.

In Example 6, the acid number of the dispersant was 76. The reducing agent mass/copper oxide mass was 0.014, the dispersing agent mass/copper oxide mass was 0.10, and the dispersion stability was A.

Using the obtained ink jet copper oxide ink (6), ink jet printing was performed under the same conditions as in Example 1, and the ink was heated and baked under the same conditions as in Example 1 for reduction to form a copper film. The inkjet printability was B. The volume resistivity of the conductive film was 18 μΩcm.

(Example 7)
1.5 g of hydrazine was added to 98.5 g of the ink-jet copper oxide ink (1) obtained in Example 1 to obtain an ink-jet copper oxide ink (7).

The inkjet copper oxide ink (7) was well dispersed. The content of cuprous oxide in 100 g was 20 g, and the particle size was 30 nm. The amount of hydrazine was 18000 ppm. Moreover, the dispersant content was 4 g.

In Example 7, the acid number of the dispersant was 76. The reducing agent mass/copper oxide mass was 0.090, the dispersing agent mass/copper oxide mass was 0.20, and the dispersion stability was A.

Using the obtained ink jet copper oxide ink (7), ink jet printing was performed under the same conditions as in Example 1, and the ink was heated and baked under the same conditions as in Example 1 for reduction to form a copper film. The inkjet printability was B. The volume resistivity of the conductive film was 20 μΩcm.

(Example 8)
0.80 g of hydrazine was added to 99.2 g of the ink-jet copper oxide ink (1) obtained in Example 1 to obtain an ink-jet copper oxide ink (8).

The inkjet copper oxide ink (8) was well dispersed. The content of cuprous oxide in 100 g was 20 g, and the particle size was 27 nm. The amount of hydrazine was 11000 ppm. Moreover, the dispersant content was 4 g.

In Example 8, the acid number of the dispersant was 76. The reducing agent mass/copper oxide mass was 0.055, the dispersing agent mass/copper oxide mass was 0.20, and the dispersion stability was A.

Using the obtained copper oxide ink for inkjet (8), inkjet printing was performed under the same conditions as in Example 1, and heating and baking were performed under the same conditions as in Example 1 for reduction to form a copper film. The inkjet printability was B. The volume resistivity of the conductive film was 21 μΩcm.

(Example 9)
0.30 g of hydrazine was added to 99.7 g of the ink-jet copper oxide ink (1) obtained in Example 1 to obtain an ink-jet copper oxide ink (9).

The inkjet copper oxide ink (9) was well dispersed. The content of cuprous oxide in 100 g was 20 g, and the particle size was 22 nm. The amount of hydrazine was 5900 ppm. Moreover, the dispersant content was 4 g.

In Example 9, the acid number of the dispersant was 76. The reducing agent mass/copper oxide mass was 0.030, the dispersing agent mass/copper oxide mass was 0.20, and the dispersion stability was A.

Using the obtained copper oxide ink for inkjet (9), inkjet printing was performed under the same conditions as in Example 1, and the ink was heated and baked under the same conditions as in Example 1 for reduction to form a copper film. The inkjet printability was B. The volume resistivity of the conductive film was 18 μΩcm.

(Example 10)
To 100 g of the inkjet copper oxide ink (1) obtained in Example 1, 1.0 g of MEGAFACE (registered trademark) F-477 (manufactured by DIC Corporation, number average molecular weight of 6700), which is a fluorine-containing organic compound, is added as an inkjet modifier. was added to obtain a copper oxide ink for inkjet (10).

The inkjet copper oxide ink (10) was well dispersed. The content of cuprous oxide in 101 g was 20 g, and the particle size was 22 nm. The amount of hydrazine was 2800 ppm. Moreover, the dispersant content was 4 g.

In Example 10, the acid number of the dispersant was 76. Further, the ratio of reducing agent mass/copper oxide mass was 0.014, the dispersing agent mass/copper oxide mass was 0.20, and the inkjet regulator mass/copper oxide ink mass for inkjet was 0.010. , dispersion stability was A.

Using the obtained copper oxide ink for inkjet (10), inkjet printing was performed under the same conditions as in Example 1, and the copper film was prepared by heating and baking under the same conditions as in Example 1 for reduction. The inkjet printability was B. The volume resistivity of the conductive film was 21 μΩcm.

(Example 11)
66.6 g of Megafac F-477 as an inkjet modifier was added to 100 g of the copper oxide ink (1) for inkjet use obtained in Example 1 to obtain copper oxide ink (11) for inkjet use.

The inkjet copper oxide ink (11) was well dispersed. The content of cuprous oxide in 167 g was 20 g, and the particle size was 24 nm. The amount of hydrazine was 1700 ppm. Moreover, the dispersant content was 4 g.

In Example 11, the acid number of the dispersant was 76. Further, the ratio of reducing agent mass/copper oxide mass was 0.014, the dispersing agent mass/copper oxide mass was 0.20, and the inkjet regulator mass/copper oxide ink mass for inkjet was 0.40. , the dispersion stability was B.

Using the obtained copper oxide ink for inkjet (11), inkjet printing was performed under the same conditions as in Example 1, and the copper film was prepared by heating and baking under the same conditions as in Example 1 for reduction. The inkjet printability was B. The volume resistivity of the conductive film was 35 μΩcm.

(Example 12)
2.0 g of MEGAFACE F-477 as an inkjet modifier was added to 100 g of the copper oxide ink for inkjet (1) obtained in Example 1 to obtain copper oxide ink for inkjet (12).

The inkjet copper oxide ink (12) was well dispersed. The content of cuprous oxide in 102 g was 20 g, and the particle size was 24 nm. The amount of hydrazine was 2700 ppm. Moreover, the dispersant content was 4 g.

In Example 12, the acid number of the dispersant was 76. Further, the ratio of reducing agent mass/copper oxide mass was 0.014, the dispersing agent mass/copper oxide mass was 0.20, and the inkjet regulator mass/copper oxide ink mass for inkjet was 0.020. , dispersion stability was A.
Using the obtained copper oxide ink for inkjet (12), inkjet printing was performed under the same conditions as in Example 1, and the copper film was prepared by heating and baking under the same conditions as in Example 1 for reduction. Inkjet printability was A. The volume resistivity of the conductive film was 22 μΩcm.

(Example 13)
42 g of MEGAFACE F-477 as an inkjet modifier was added to 100 g of the copper oxide ink for inkjet (1) obtained in Example 1 to obtain copper oxide ink for inkjet (13).

The inkjet copper oxide ink (13) was well dispersed. The content of cuprous oxide in 142 g was 20 g, and the particle size was 28 nm. The amount of hydrazine was 1900 ppm. Moreover, the dispersant content was 4 g.

In Example 13, the acid number of the dispersant was 76. Further, the ratio of reducing agent mass/copper oxide mass was 0.014, the dispersing agent mass/copper oxide mass was 0.20, and the inkjet regulator mass/copper oxide ink mass for inkjet was 0.30. , the dispersion stability was B.

Using the obtained copper oxide ink for inkjet (13), inkjet printing was performed under the same conditions as in Example 1, and the copper film was prepared by heating and baking under the same conditions as in Example 1 for reduction. Inkjet printability was A. The volume resistivity of the conductive film was 30 μΩcm.

(Example 14)
5 g of MEGAFACE F-477 as an inkjet modifier was added to 100 g of the copper oxide ink for inkjet (1) obtained in Example 1 to obtain copper oxide ink for inkjet (14).

The inkjet copper oxide ink (14) was well dispersed. The content of cuprous oxide in 105 g was 20 g, and the particle size was 22 nm. The amount of hydrazine was 2600 ppm. Moreover, the dispersant content was 4 g.

In Example 14, the acid number of the dispersant was 76. Further, the ratio of reducing agent mass/copper oxide mass was 0.014, the dispersing agent mass/copper oxide mass was 0.20, and the inkjet regulator mass/copper oxide ink mass for inkjet was 0.048. , dispersion stability was A.

Using the obtained copper oxide ink for inkjet (14), inkjet printing was performed under the same conditions as in Example 1, and the ink was heated and baked under the same conditions as in Example 1 for reduction to form a copper film. The inkjet printability was S. The volume resistivity of the conductive film was 24 μΩcm.

(Example 15)
25 g of MEGAFACE F-477 as an inkjet modifier was added to 100 g of the copper oxide ink for inkjet (1) obtained in Example 1 to obtain copper oxide ink for inkjet (15).

The inkjet copper oxide ink (15) was well dispersed. The content of cuprous oxide in 125 g was 20 g, and the particle size was 24 nm. The amount of hydrazine was 2200 ppm. Moreover, the dispersant content was 4 g.

In Example 15, the dispersant had an acid number of 76. Further, the ratio of reducing agent mass/copper oxide mass was 0.014, the dispersing agent mass/copper oxide mass was 0.20, and the inkjet regulator mass/copper oxide ink mass for inkjet was 0.20. , dispersion stability was A.

Using the obtained copper oxide ink for inkjet (15), inkjet printing was performed under the same conditions as in Example 1, and the copper film was prepared by heating and baking under the same conditions as in Example 1 for reduction. The inkjet printability was S. The volume resistivity of the conductive film was 28 μΩcm.

(Example 16)
1.0 g of Surflon S611 (manufactured by Seimi Chemical Co., Ltd., number average molecular weight: 11000) was added as an inkjet modifier to 100 g of the copper oxide ink for inkjet (1) obtained in Example 1 to obtain copper oxide ink for inkjet (16). .

The inkjet copper oxide ink (16) was well dispersed. The content of cuprous oxide in 101 g was 20 g, and the particle size was 22 nm. The amount of hydrazine was 2800 ppm. Moreover, the dispersant content was 4 g.

In Example 16, the acid number of the dispersant was 76. Further, the ratio of reducing agent mass/copper oxide mass was 0.014, the dispersing agent mass/copper oxide mass was 0.20, and the inkjet regulator mass/copper oxide ink mass for inkjet was 0.010. , dispersion stability was A.

Using the obtained copper oxide ink for inkjet (16), inkjet printing was performed under the same conditions as in Example 1, and the copper film was prepared by heating and baking under the same conditions as in Example 1 for reduction. The inkjet printability was B. The volume resistivity of the conductive film was 22 μΩcm.

(Example 17)
66.6 g of Surflon S611 as an inkjet modifier was added to 100 g of the copper oxide ink for inkjet (1) obtained in Example 1 to obtain copper oxide ink for inkjet (17).

The inkjet copper oxide ink (17) was well dispersed. The content of cuprous oxide in 167 g was 20 g, and the particle size was 24 nm. The amount of hydrazine was 1800 ppm. Moreover, the dispersant content was 4 g.

In Example 17, the dispersant had an acid number of 76. Further, the ratio of reducing agent mass/copper oxide mass was 0.014, the dispersing agent mass/copper oxide mass was 0.20, and the inkjet regulator mass/copper oxide ink mass for inkjet was 0.40. , the dispersion stability was B.

Using the obtained copper oxide ink for inkjet (17), inkjet printing was performed under the same conditions as in Example 1, and the copper film was prepared by heating and baking under the same conditions as in Example 1 for reduction. The inkjet printability was B. The volume resistivity of the conductive film was 38 μΩcm.

(Example 18)
1.0 g of PEG400 (manufactured by Kanto Kagaku, number average molecular weight: 400) was added as an inkjet regulator to 100 g of the copper oxide ink for inkjet (1) obtained in Example 1 to obtain copper oxide ink for inkjet (18).

The inkjet copper oxide ink (18) was well dispersed. The content of cuprous oxide in 101 g was 20 g, and the particle size was 24 nm. The amount of hydrazine was 2800 ppm. Moreover, the dispersant content was 4 g.

In Example 18, the dispersant had an acid number of 76. Further, the ratio of reducing agent mass/copper oxide mass was 0.014, the dispersing agent mass/copper oxide mass was 0.20, and the inkjet regulator mass/copper oxide ink mass for inkjet was 0.010. , dispersion stability was A.

Using the obtained copper oxide ink for inkjet (18), inkjet printing was performed under the same conditions as in Example 1, and the copper film was prepared by heating and baking under the same conditions as in Example 1 for reduction. The inkjet printability was B. The volume resistivity of the conductive film was 25 μΩcm.

(Example 19)
66.6 g of PEG400 as an inkjet regulator was added to 100 g of the copper oxide ink (1) for inkjet use obtained in Example 1 to obtain copper oxide ink (19) for inkjet use.

The inkjet copper oxide ink (19) was well dispersed. The content of cuprous oxide in 167 g was 20 g, and the particle size was 28 nm. The amount of hydrazine was 1800 ppm. Moreover, the dispersant content was 4 g.

In Example 19, the dispersant had an acid number of 76. Further, the ratio of reducing agent mass/copper oxide mass was 0.014, the dispersing agent mass/copper oxide mass was 0.20, and the inkjet regulator mass/copper oxide ink mass for inkjet was 0.40. , the dispersion stability was B.

Using the obtained copper oxide ink for inkjet (19), inkjet printing was performed under the same conditions as in Example 1, and the copper film was prepared by heating and baking under the same conditions as in Example 1 for reduction. The inkjet printability was B. The volume resistivity of the conductive film was 30 μΩcm.

(Example 20)
100 g of MEGAFACE F-477 as an inkjet regulator was added to 100 g of the copper oxide ink for inkjet (1) obtained in Example 1 to obtain copper oxide ink for inkjet (20).

The inkjet copper oxide ink (20) was dispersed. The content of cuprous oxide in 200 g was 20 g, and the particle size was 50 nm. The amount of hydrazine was 1400 ppm. Moreover, the dispersant content was 4 g.

In Example 20, the acid number of the dispersant was 76. Further, the ratio of reducing agent mass/copper oxide mass was 0.014, the dispersing agent mass/copper oxide mass was 0.20, and the inkjet regulator mass/copper oxide ink mass for inkjet was 0.50. , the dispersion stability was C.

Using the obtained copper oxide ink for inkjet (19), inkjet printing was performed under the same conditions as in Example 1, and the copper film was prepared by heating and baking under the same conditions as in Example 1 for reduction. The inkjet printability was B. The volume resistivity of the conductive film was 70 μΩcm.

(Comparative example 1)
Dissolve 806 g of copper (II) acetate monohydrate (manufactured by Wako Pure Chemical) in a mixed solvent of 7560 g of water and 3494 g of 1,2-propylene glycol (manufactured by Wako Pure Chemical) and add hydrazine monohydrate (manufactured by Wako Pure Chemical). ) was added and stirred. After that, it was separated into a supernatant and a precipitate by centrifugation.

54.8 g of BYK145 and 920 g of ethanol (manufactured by Kanto Kagaku Co., Ltd.) were added to 390 g of the resulting precipitate and dispersed using a homogenizer under a nitrogen atmosphere to obtain 1365 g of a cuprous oxide dispersion.

In Comparative Example 1, ethanol (having a boiling point of about 79° C.) is contained as a solvent in the cuprous oxide dispersion.

In Comparative Example 1, the content of cuprous oxide in 100 g was 20 g, and the particle size was 21 nm. The amount of hydrazine was 2900 ppm. Moreover, in Comparative Example 1, the acid value of the dispersant was 76. The reducing agent mass/copper oxide mass was 0.015, the dispersant mass/copper oxide mass was 0.2, and the dispersion stability was A.

The obtained copper oxide ink DMC-11601 cartridge (manufactured by Fujifilm) was filled, and inkjet printing was performed using a Dimatrix material printer (manufactured by Fujifilm) under the conditions of line: 20 μm and space: 20 μm. Inkjet printability was rated as C because lines could not be drawn due to the occurrence of discontinuities and blurring, and the droplets landed in places other than lines.

(Comparative example 2)
Dissolve 806 g of copper (II) acetate monohydrate (manufactured by Wako Pure Chemical) in a mixed solvent of 7560 g of water and 3494 g of 1,2-propylene glycol (manufactured by Wako Pure Chemical) and add hydrazine monohydrate (manufactured by Wako Pure Chemical). ) was added and stirred. After that, it was separated into a supernatant and a precipitate by centrifugation. DisperBYK-170 (manufactured by BYK Chemie) 13.7 g (dispersant content: 4 g) and ethanol (manufactured by Kanto Kagaku Co., Ltd.) 961 g are added to 390 g of the obtained precipitate, dispersed and oxidized using a homogenizer under a nitrogen atmosphere. 1365 g of cuprous dispersion were obtained.

In Comparative Example 2, the cuprous oxide dispersion contained ethanol (having a boiling point of about 79° C.) as a solvent.

The content of cuprous oxide in 100 g was 20 g. The solubility was poor and the copper oxide particles aggregated, making it impossible to form an ink. The amount of hydrazine was 2900 ppm. The acid value of the dispersant was 11. The reducing agent mass/copper oxide mass was 0.015, the dispersant mass/copper oxide mass was 0.2, and the dispersion stability was C. Moreover, since it could not be made into an ink, inkjet printing could not be performed (inkjet printability was C).

(Comparative Example 3)
Dissolve 806 g of copper (II) acetate monohydrate (manufactured by Wako Pure Chemical) in a mixed solvent of 7560 g of water and 3494 g of 1,2-propylene glycol (manufactured by Wako Pure Chemical) and add hydrazine monohydrate (manufactured by Wako Pure Chemical). ) was added and stirred. After that, it was separated into a supernatant and a precipitate by centrifugation.

To 390 g of the obtained precipitate, 110 g of BYK145 and 490 g of diethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.) were added as dispersants and dispersed using a homogenizer under a nitrogen atmosphere.

Then, concentration by the UF membrane module and dilution by diethylene glycol were repeated to obtain a cuprous oxide dispersion (copper oxide ink). γ-Butyrolactone (manufactured by Wako Pure Chemical Industries) was added to the obtained cuprous oxide dispersion to adjust the composition ratio to the following, but the copper oxide particles aggregated and could not be made into an ink.
Cu2O/DEG/BYK145/γ-butyrolactone/hydrazine = 20/36/8/35.7/0.3 (unit: % by mass).

The content of cuprous oxide in 100 g was 20 g, and the amount of hydrazine was 2800 ppm. Moreover, the dispersant content was 8 g.

In Comparative Example 3, the acid value of the dispersant was 76. The reducing agent mass/copper oxide mass was 0.014, the dispersant mass/copper oxide mass was 0.40, and the dispersion stability was C. Moreover, since it could not be made into an ink, inkjet printing could not be performed (inkjet printability was C).

(Comparative Example 4)
Dissolve 806 g of copper (II) acetate monohydrate (manufactured by Wako Pure Chemical) in a mixed solvent of 7560 g of water and 3494 g of 1,2-propylene glycol (manufactured by Wako Pure Chemical) and add hydrazine monohydrate (manufactured by Wako Pure Chemical). ) was added and stirred. After that, it was separated into a supernatant and a precipitate by centrifugation.

490 g of diethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.) was added to 390 g of the obtained precipitate, and dispersed using a homogenizer under a nitrogen atmosphere.

Then, concentration by the UF membrane module and dilution by diethylene glycol were repeated to obtain a cuprous oxide dispersion (copper oxide ink). γ-Butyrolactone (manufactured by Wako Pure Chemical Industries) was added to the obtained cuprous oxide dispersion to adjust the composition ratio to the following, but the copper oxide particles aggregated and could not be made into an ink.
Cu2O/DEG/BYK145/γ-butyrolactone/hydrazine = 20/36/0/43.7/0.3 (unit: % by mass).

The content of cuprous oxide in 100 g was 20 g, and the amount of hydrazine was 2800 ppm. In Comparative Example 4, the reducing agent mass/copper oxide mass was 0.014, the dispersant mass/copper oxide mass was 0.0, and the dispersion stability was C. Moreover, since it could not be made into an ink, inkjet printing could not be performed (inkjet printability was C).

(Comparative Example 5)
3.0 g of hydrazine was added to 97 g of the ink-jet copper oxide ink (1) obtained in Example 1.
Copper oxide particles agglomerated and could not be made into an ink.
Cu2O/DEG/BYK145/γ-butyrolactone/hydrazine = 20/36/4/36/4 (unit: % by mass).

The content of cuprous oxide in 100 g was 20 g, and the amount of hydrazine was 33000 ppm. In Comparative Example 5, the reducing agent mass/copper oxide mass was 0.20, the dispersant mass/copper oxide mass was 0.20, and the dispersion stability was C. Moreover, since it could not be made into an ink, inkjet printing could not be performed (inkjet printability was C).

(Comparative Example 6)
To 36 g of diethylene glycol and 40 g of γ-butyrolactone (manufactured by Wako Pure Chemical Industries), 20 g of cuprous oxide (MP-CU2O-25 manufactured by EM Japan) and 4.0 g of DisperBYK-145 (manufactured by Big Chemie) were added, and the mixture was homogenized under a nitrogen atmosphere with a homogenizer. Although dispersed, the copper oxide particles agglomerated and could not be made into an ink.
Cu2O/DEG/BYK145/γ-butyrolactone/hydrazine = 20/36/4/40/0 (unit: % by mass).

The content of cuprous oxide in 100 g was 20 g, and the amount of hydrazine was 0.0 ppm. The particle size of cupric oxide was 190 nm. In Comparative Example 6, the reducing agent mass/copper oxide mass was 0.0, the dispersant mass/copper oxide mass was 0.20, and the dispersion stability was C. Moreover, since it could not be made into an ink, inkjet printing could not be performed (inkjet printability was C).

Experimental results of Examples 1 to 20 and Comparative Examples 1 to 6 are shown in Table 1 below. The amount of "hydrazine" shown in Table 1 is a value rounded to the second decimal place.

In Examples 1 to 20, the value of (mass of reducing agent/mass of copper oxide) was 0.0001 or more and 0.10 or less, and the value of (mass of dispersant/mass of copper oxide) was 0.0050 or more and 0.0050. At least two kinds of solvents having a boiling point of 100° C. or more and a boiling point of 30 or less were contained. Therefore, in Examples 1 to 20, printing was possible by the ink-jet method, and hydrazine was used as a reducing agent. done.

Further, in Examples 1 to 20, in addition to the above, the acid value of the dispersant is 20 or more and 130 or less, which can improve dispersion stability and enable high-definition inkjet printing. It is possible to improve the low resistance of the wiring.

On the other hand, in Comparative Examples 1 to 6 using ethanol, it was difficult to fabricate copper wiring by the inkjet method in the dispersion liquid. In Comparative Example 2, in which ethanol was used and the acid value of the dispersant was less than 20, ink jet printing and resistance measurement could not be performed because the copper oxide ink was agglomerated.

With the copper oxide ink of the present invention, wiring can be produced using an ink jet method, and a conductive film with little disconnection or damage can be obtained by plasma, heat, or light baking treatment. Therefore, the copper oxide ink of the present invention is suitably used for manufacturing RFIDs, antennas, printed wiring boards, electronic devices, transparent conductive films, electromagnetic wave shields, antistatic films, and the like.

REFERENCE SIGNS LIST 1 copper oxide ink for inkjet 2 copper oxide 3 phosphate ester salt 10 conductive substrate 11 substrate 12 insulating region 13 conductive pattern

Claims (6)

The solvent contains copper oxide, a dispersant, a reducing agent , and an inkjet modifier ,
The content of the reducing agent is within the range of the following formula (1),
The content of the dispersant is within the range of the following formula (2),
containing at least two of the solvents having a boiling point of 100° C. or higher,
the inkjet modifier is selected from graphene, graphene oxide, carbon nanotubes, acrylic polymers, acrylic latexes, silicone polymers, acrylic silicone latexes, thiophene polymers, fluorine-containing organic compounds, and polyethylene glycol;
The inkjet modifier has a number average molecular weight of 350 or more and 30000 or less,
The content of the inkjet modifier is within the range of the following formula (3)
A copper oxide ink for inkjet, characterized by:
0.0001 ≤ (mass of reducing agent/mass of copper oxide) ≤ 0.10 (1)
0.0050 ≤ (mass of dispersant/mass of copper oxide) ≤ 0.30 (2)
0.048 ≤ (mass of inkjet modifier/mass of copper oxide ink for inkjet) ≤ 0.20 (3) 2. The ink jet copper oxide ink according to claim 1, wherein the copper oxide is cuprous oxide. The reducing agent is hydrazine, hydrazine hydrate, sodium, carbon, potassium iodide, oxalic acid, iron (II) sulfide, sodium thiosulfate, ascorbic acid, tin (II) chloride, diisobutylaluminum hydride, formic acid, hydrogen 3. The ink jet copper oxide ink according to claim 1, comprising at least one selected from the group consisting of sodium borate and sulfite. 4. The inkjet copper oxide ink according to any one of claims 1 to 3, wherein the dispersant has an acid value of 20 or more and 130 or less. Using the copper oxide ink according to any one of claims 1 to 4 , a pattern is formed on a substrate using an inkjet device, plasma is generated in an atmosphere containing a reducing gas, and the pattern is baked. A method for manufacturing a conductive substrate, characterized by performing a treatment. A pattern is formed on a substrate using the copper oxide ink according to any one of claims 1 to 4 using an inkjet device, and then the pattern is subjected to heat or light irradiation treatment. A method for manufacturing a conductive substrate.

Images