JP2011142052A - Copper conductor ink, conductive substrate, and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copper conductor ink capable of forming a conductive layer with high adhesion with a substrate without reducing its conductivity, and a manufacturing method capable of manufacturing the conductive substrate wherein adhesion between the conductive layer and the substrate is high and conductivity of the conductive layer is high. <P>SOLUTION: In the copper conductor ink including copper nano-particles, and thermosetting resin before being heat-cured, a content volume of the thermosetting resin is greater than a volume of one quarter of a gap volume at the time of most densely filling up the copper nano-particles, and is smaller than the gap volume. Further, the manufacturing method for a conductive substrate includes a process A of forming a coated layer by applying the copper conductor ink on the substrate and drying the coated layer, a process B of applying conductible treatment to the dried coated layer and changing the coated layer into a conductive layer, and a process C of performing heat-curing of the thermosetting resin between the process A and the process B or after the process B. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a copper conductor ink used for forming a copper wiring pattern and the like, a method for producing a conductive substrate using the copper conductor ink, and a conductive substrate.

From the advantages of low energy, low cost, high throughput, on-demand production, etc., the formation of wiring patterns by the printing method is considered promising. This object is realized by forming a pattern by a printing method using an ink paste containing a metal element and then imparting metal conductivity to the printed wiring pattern.
Conventionally, a paste obtained by mixing flaky silver or copper with a binder of a thermoplastic resin or a thermosetting resin together with an organic solvent, a curing agent, a catalyst, or the like has been used for this purpose. This metal paste is used by applying it to an object by a dispenser or screen printing and drying it at room temperature, or heating it to about 150 ° C. to cure the binder resin to form a conductive film. . In the conductive film thus obtained, only a part of the internal metal particles are brought into physical contact with each other to establish conduction, and the cured resin exhibits strength of the conductive layer and adhesion to the substrate. Yes. However, in such a conductive paste, conduction is obtained by physical contact between particles, and a binder remains between some silver particles to inhibit contact. However, it is in the range of 10 ⁻⁶ to 10 ⁻⁷ Ω · m, and 10 to 100 compared to the volume resistivity 16 × 10 ⁻⁹ Ω · m and 17 × 10 ⁻⁹ Ω · m of metallic silver and copper. The value is twice that of the metal film. Further, in the conventional silver paste, since the silver particles are in the form of flakes having a particle diameter of 1 to 100 μm, it is impossible in principle to print a wiring having a line width equal to or smaller than the particle diameter of the flaky silver particles. In addition, from the miniaturization of wiring and application to the ink jet method, ink using particles having a particle size of 100 nm or less is required. From these points, conventional silver paste is not suitable for forming a fine wiring pattern. is there.

In order to overcome the disadvantages of these silver and copper pastes, a method of forming a wiring pattern using metal nanoparticles has been studied, and a method using gold or silver nanoparticles has been established (for example, Patent Documents 1 and 2). reference.). Specifically, in the sintered body type wiring layer obtained by drawing an extremely fine circuit pattern using a dispersion liquid containing gold or silver nanoparticles, and then performing sintering between the metal nanoparticles, It is possible to form a wiring having a width and a space between wirings of 5 to 50 μm and a volume resistivity of 1 × 10 ⁻⁸ Ω · m or less. However, when precious metal nanoparticles such as gold and silver are used, the material itself is expensive, so the production unit price of such a dispersion for ultra fine printing is high, and it is a great economic factor for widespread use as a general-purpose product. It is an obstacle. Furthermore, with silver nanoparticles, as the wiring width and inter-wiring space become narrower, it has emerged as a drawback and problem of reduced insulation between circuits due to electromigration.

  As the metal nanoparticle dispersion for forming the wiring, it is expected to use copper, which has less electromigration and is considerably less expensive than gold and silver. Since copper particles are more easily oxidized than noble metals, surface treatment agents having an anti-oxidation function other than the purpose of improving dispersibility are used. For such purposes, a polymer having a substituent that interacts with the copper surface and a surface treatment agent having a long-chain alkyl group (for example, see Patent Documents 3 and 4) are used.

  As described above, the ink using the metal nanoparticles contains a large amount of a dispersant for improving dispersibility, a surface protective agent for preventing oxidation of the metal nanoparticles and, in some cases, a reducing agent, and a conductor. Means for decomposing these dispersants, surface protective agents and the like have been proposed for the treatment to be converted (see, for example, Patent Documents 6 to 7).

  On the other hand, the wiring pattern using metal nanoparticles does not contain a resin component such as a conductive paste that positively gives adhesiveness, and further, the particles are sintered from the state that they are physically placed on the substrate. The produced conductor layer has a drawback that it easily peels off from the substrate. In addition, the conductor layer produced by the sintering of the particles contains a large amount of inter-particle gaps and voids produced by the removal of the surface protective agent in the layer, the conductor layer becomes brittle, and the above-mentioned lack of adhesiveness Together, the adhesion of the conductor layer is a major problem.

Therefore, it is conceivable to add a resin to improve adhesion, but since the ink contains a large amount of a dispersant, a surface protective agent, etc. as described above, it is difficult to add a resin. Even if a resin is added, it is decomposed together with the dispersant and the surface protective agent in the process of forming a conductor, and a sufficient effect cannot be obtained.
Therefore, attempts have been reported to improve the adhesion by improving the adhesion to the substrate side (see, for example, Patent Document 8).

JP 2004-273205 A JP 2003-203522 A Japanese Patent No. 3599950 Japanese Patent Laying-Open No. 2005-081501 JP 2006-26602 A JP 2006-210872 A JP 2004-119686 A JP 2008-200557 A

This invention is made | formed in view of the said prior art, and makes it a subject to achieve the following objectives.
An object of the present invention is to provide a copper conductor ink capable of forming a conductive layer having high adhesion to a substrate without reducing the conductivity.
Another object of the present invention is to provide a method for producing a conductive substrate capable of producing a conductive substrate having high adhesion between the conductive layer and the substrate and having high conductivity of the conductive layer.
Still another object of the present invention is to provide a conductive substrate having a conductive layer having high conductivity and high adhesion to the substrate.

In order to solve the above-mentioned drawbacks, the inventors of the present invention have made it possible to make the conductor of ink using copper nanoparticles, the organic impurities represented by the surface protective agent and the dispersing agent prevent the contact between the particles and make the conductor, low volume resistance. Although the rate is hindered, the inventors have intensively studied that the influence of organic impurities can be minimized if the volume is smaller than the space (void) remaining even when the nanoparticles are packed in close-packed manner, and the present invention has been achieved. Further, it was found that if the addition of 41 vol% or less with respect to the copper particles, the volume resistivity hardly increases, and if 6 vol% or more of the resin is added, the adhesion is improved.
That is, the means for solving the above problems are as follows.

(1) A copper conductor ink containing copper-based nanoparticles and a thermosetting resin before thermosetting,
The copper conductor ink is characterized in that the volume of the thermosetting resin is larger than 1/4 of the void volume when the copper-based nanoparticles are closely packed and smaller than the void volume.

(2) The copper conductor ink according to (1), wherein the thermosetting resin is contained in an amount of 6 to 41 vol% with respect to the volume of the copper-based nanoparticles.

(3) The copper conductor ink as described in (1) or (2) above, wherein the dynamic viscosity at 25 ° C. is 5 to 20 mPa · s.

(4) The copper-based nanoparticles are composed of particles having a core / shell structure in which the core portion is copper and the shell portion is copper oxide and / or copper oxide particles (1) to (1) to The copper conductor ink according to any one of (3).

(5) The thermosetting resin is at least one selected from the group consisting of an epoxy resin, an isocyanate resin, a phenol resin, a resole resin, and a siloxane resin. The copper conductor ink according to any one of the above.

(6) A dispersion medium having a hydrogen bond term in the Hansen solubility parameter of 8 MPa ^1/2 or less and a polar term in the Hansen solubility parameter of 11 MPa ^1/2 or more is used as the dispersion medium. The copper conductor ink according to any one of 1) to (5).

(7) The copper conductor ink according to (6), which is prepared without using a dispersant for the copper-based nanoparticles.

(8) Step A of applying the copper conductor ink according to any one of (1) to (7) on a substrate to form a coating layer, and drying the coating layer A;
Step B for converting the dried coating layer into a conductive layer by conducting a conductive treatment;
Step C for thermosetting the thermosetting resin between Step A and Step B or after Step B;
The manufacturing method of the electroconductive board | substrate characterized by the above-mentioned.

(9) A conductive substrate manufactured by the method for manufacturing a conductive substrate according to (8).

ADVANTAGE OF THE INVENTION According to this invention, the copper conductor ink which can form a copper wiring pattern with high adhesiveness with a board | substrate can be provided, without reducing electroconductivity.
Moreover, according to this invention, the manufacturing method of the electroconductive board | substrate which can manufacture the electroconductive board | substrate with high adhesiveness of an electroconductive layer and a board | substrate and with high electroconductivity of this electroconductive layer can be provided.
Furthermore, according to the present invention, a conductive substrate having a conductive layer having high conductivity and high adhesion to the substrate can be provided.

It is a top view which shows the board | substrate which has the copper foil pattern used in the Example. It is a figure shown with a graph about the shear viscosity of the copper conductor ink prepared in Example 1, the comparative example 2, and the comparative example 4. FIG. (A) is in Example 1, (B) is in Example 2, (C) is in Comparative Example 2, and the coating layer formed using the prepared copper conductor ink is subjected to conductor treatment for 5 hours. It is a drawing substitute photograph showing the surface after progress. (A) in Example 1, (B) in Example 2, (C) in Comparative Example 2, a drawing-substituting photograph showing the surface of the copper conductor layer after the tape peel test (left side of each photograph) Is the tape side, and the right side is the substrate side.). It is a figure shown with a graph about the shear viscosity of the copper conductor ink prepared in Example 3 and Comparative Example 3. FIG. It is a figure which shows the surface resistance before and behind tape peeling of Examples 4-10 by a graph. It is a figure which shows the surface resistance before and behind tape peeling of Examples 11-17 by a graph.

<Copper conductor ink>
The copper conductor ink of the present invention is a copper conductor ink containing copper-based nanoparticles and a thermosetting resin before thermosetting, and the content volume of the thermosetting resin is the closest to the copper-based nanoparticles. It is characterized by being larger than a quarter of the void volume when filled and smaller than the void volume.
More specifically, in the copper conductor ink of the present invention, a resin of 41 vol% or less based on copper nanoparticles is added to a dispersion of copper nanoparticles having a copper oxide surface that does not contain a surface protective agent or a dispersant. It is a copper conductor ink in which the added ink is printed or applied and then dried to conduct a conductor treatment including formation of metal bonds between particles, and the resin remains in the conductor layer even after the conductor treatment.
Below, the component contained in the copper conductor ink of this invention is demonstrated.

[Copper nanoparticles]
As the copper-based nanoparticles, particles having a core / shell structure in which the core portion is copper and the shell portion is copper oxide (hereinafter referred to as “copper / copper oxide core-shell particles”) or copper oxide particles are used. Yes, any of them may be used alone or both may be used in combination.

(Copper / copper oxide core-shell particles)
As the copper / copper oxide core-shell particles, for example, those produced by irradiating a raw metal compound dispersed in an organic solvent not showing a reducing action with laser light under stirring can be used. Alternatively, copper / copper oxide core-shell particles produced by introducing a copper raw material into a plasma flame in an inert gas and quenching with a cooling inert gas can also be used. The characteristics of the copper / copper oxide core-shell particles using laser light are the characteristics of the resulting particles: the type of raw copper compound, the particle size of the raw copper compound, the amount of the raw copper compound, the type of organic solvent, the wavelength of the laser light Control by appropriately selecting various conditions such as laser light output, laser light irradiation time, temperature, stirring state of copper compound, type of gas bubbling gas introduced into organic solvent, amount of bubbling gas, additive, etc. Is done.
Details will be described below.

A. Raw material The raw material is a copper compound, and specifically, copper oxide, cuprous oxide, copper sulfide, copper octylate, copper chloride and the like can be used.
The size of the raw material is important. Even when the laser beam having the same energy density is irradiated, the smaller the particle size of the metal compound powder of the raw material, the more efficiently the core / shell particles having a smaller particle size can be obtained. Moreover, the raw material of various shapes, such as a spherical shape, a crushed shape, plate shape, scale shape, rod shape, can be used for a shape.

B. Laser light The wavelength of the laser light is preferably such that the absorption coefficient of the copper compound is as large as possible. However, in order to suppress the crystal growth of nano-sized copper fine particles, the wavelength of the short wavelength has a low effect as a heat ray. It is preferable to use laser light.
For example, an Nd: YAG laser, an excimer laser, a semiconductor laser, a dye laser, or the like can be used as the laser light. Moreover, pulse irradiation is preferable in order to irradiate many copper compounds with a high energy laser under the same conditions.

C. Organic solvent (dispersion medium during particle generation)
As the organic solvent used for the dispersion medium of the copper compound during particle formation, it is preferable to use a ketone solvent such as acetone, methyl ethyl ketone, γ-butyrolactone, cyclohexanone, etc., in order to obtain nano-sized particles, but dimethylacetamide Also, polar solvents such as N-methylpyrrolidone and propylene glycol monoethyl ether, and hydrocarbon solvents such as toluene and tetradecane can be used. Moreover, you may use 1 type individually or in combination of 2 or more types. When an organic solvent exhibiting reducibility is used, the oxide film that forms the shell of the copper particles is reduced, and the metal is exposed to form aggregates, thereby impairing the dispersion stability of the particles. . Therefore, it is preferable to use an organic solvent that does not exhibit a reducing action.
In addition, the preparation methods of the above copper / copper oxide core-shell particle | grains are an example, and this invention is not limited to it. For example, if there is a commercially available product, it may be used.

  The copper / copper oxide core-shell particles used in the present invention preferably have a primary particle number average particle diameter of 1 to 1,000 nm, more preferably 1 to 500 nm, and more preferably 10 to 100 nm. Further preferred.

(Copper oxide particles)
The copper oxide particles are spherical or lump particles made of cuprous oxide, cupric oxide or a mixture thereof. For example, copper oxide nanoparticles or Nissin made by the vapor phase evaporation method manufactured by CI Kasei. You may use what is obtained as a commercial item like the copper oxide nanoparticle synthesize | combined by the plasma flame method made from engineering.

  In the present invention, when copper oxide is used as particles, from the viewpoint of dispersion stability in the dispersion, the primary average particle diameter is preferably 1 to 10,000 nm, and preferably 2 to 1,000 nm. Is more preferable, and it is preferable that it is 3-300 nm.

[Additive resin]
The resin to be added has adhesiveness to the substrate, is soluble in the dispersion medium of the copper-based nanoparticles, and the copper-based particle dispersion added with the resin is compared with the copper-based particle dispersion without addition. Thus, a resin with little increase in aggregation and viscosity is preferred.
Specifically, due to restrictions as an inkjet ink, the copper-based particle dispersion added with a resin does not contain aggregates or coarse particles of 10 μm or more, has a dynamic viscosity at 25 ° C. of 5 to 20 mPa · s, The concentration is desirably 10 mass% or more.

(resin)
As the resin component, a three-dimensional crosslinked resin is used from the viewpoint of reinforcing the copper-based nanoparticle layer (conductive layer) that has been made into a conductor and improving the adhesion to the substrate.
Specific examples include epoxy resins, isocyanate resins, polyurea resins, phenol resins, acrylic resins, polyimide resins, siloxane resins, alkoxysilane condensates, organoaluminum condensates, polyether resins, etc. Among them, thermosetting resins. An epoxy resin, isocyanate resin, phenol resin, resol resin, or siloxane resin is more preferable. A combination of these resins can also be used as the resin component.
Regardless of which resin component is used, it may cause viscosity and thixotropy increase and aggregation due to floc formation between particles, so it does not contain hydrogen-bonding substituents or ionic substituents as resin substituents Is desirable. Specifically, primary, secondary amines and amine salts, sulfonic acid groups and sulfonates, phosphate groups and phosphates, carboxylic acids and carboxylic acid salts are preferably not included.

  For the same reason, it is preferable that the resin component catalyst, additive, and impurities as amine, methanol, ethanol, water, and ionic substances are not contained in an amount of 10% by mass or more, depending on the amount of resin resin added.

  The space ratio is 26.0 vol% in close-packing (six-method close-packing) of particles of a single particle size obtained from theoretical calculation, and 20.7 vol% when considering a secondary sphere that just enters the close-packing gap. Space is generated between particles (Hiroaki Yanagida, Michitaka Suzuki: “Section 6 Properties of Aggregates”, Fine Particle Engineering, Volume 1, Basic Technology, Fuji Techno System, p 168). That is, if the addition amount of the resin is 20 vol% or less, the resin is pushed out into the space between the particles during the conductor treatment, and the particles can be sintered. Actually, it is assumed that there is a reduction in the distance between particles accompanying sintering, and the allowable amount of resin addition is expected to be small. As a result of investigations by the inventors, it was found that if the amount of resin added is 29 vol% or less, there is no effect on the volume resistivity after the formation of a conductor. Further, as a result of the examination, when the resin addition amount is less than 6 vol%, the effect of improving the adhesion is not seen. Therefore, the resin addition amount needs to be 6 vol% or more and 29 vol% or less.

[Dispersion medium]
Examples of the dispersion medium used in the copper conductor ink of the present invention include γ-butyrolactone, N-methylpyrrolidone, propylene carbonate, ethylene glycol sulfite, acetonitrile, and sulfolane. Of these, γ-butyrolactone, propylene carbonate, ethylene glycol sulfite, and sulfolane are particularly preferable.
In addition, since the dispersion medium causes aggregation and precipitation, it is preferable that the dispersion medium does not contain an ionic component and a large amount of water.

On the other hand, the dispersion medium defined by the Hansen solubility parameter is preferable as the dispersion medium, particularly for the purpose of obtaining a dispersion having a low viscosity and less aggregation as provided for ink jet inks. The Hansen solubility parameter is described in Japanese Patent Application No. 2008-62969. Specifically, a dispersion medium having a hydrogen bond term in the Hansen solubility parameter of 8 MPa ^1/2 or less and a polar term in the Hansen solubility parameter of 11 MPa ^1/2 or more is preferable.

The reason why the dispersibility of the particles is improved by using a dispersion medium that satisfies the above conditions is considered to be that the free energy decreases due to the contact between the copper oxide surface and the dispersion medium, and the dispersion state becomes more stable.
Here, the Hansen solubility parameter is one type of method for defining the solubility parameter of the solvent. For details, for example, “INDUSTRIAL SOLVENTSHANDBOOK” (pp.35-68, Marcel Dekker, Inc., 1996) “HANSEN SOLUBILITY PARAMETERS: A USER'S HANDBOOK” (pp.1-41, CRC Press, 1999) “DIRECTORYOF SOLVENTS” (pp.22-29, Blackie Academic & Professional, 1996). The Hansen solubility parameter is a parameter specific to a substance introduced to estimate the affinity between a solvent and a solute. This parameter determines how much the free energy of the system decreases or increases when a solvent and solute come into contact with each other. Can be guessed from. That is, a solvent that can dissolve a certain substance has a certain range of parameters. The inventors of the present invention have considered that the same is true between the particle surface and the dispersion medium. That is, it was analogized that in order to stabilize in terms of energy when a particle having a copper oxide surface comes into contact with the dispersion medium, the dispersion medium has a solubility parameter in a certain region.

The dispersion medium is preferably hydrogen bond in Hansen parameters is ^{8 MPa 1/2} or less, although it is shown that low hydrogen-bonding, is preferably ^{9 MPa 1/2} or less, 8 MPa ^{1 /} More preferably, it is ² or less. If it exceeds 8 MPa ^1/2 , the dispersion system aggregates, resulting in thickening, sedimentation of the particles, and separation of the particles and the dispersion medium. The lower limit is usually 0 MPa ^1/2 .

Further, the dispersion medium is preferably polar term of Hansen parameters is ^{11 MPa 1/2} or more, although a show that highly polar is, it is preferably ^{11 MPa 1/2} or more, 12 MPa ^{1 /} More preferably, it is ² or more. If it is less than 11 MPa ^1/2 , the dispersion system aggregates, resulting in thickening, sedimentation of particles, and separation of particles and dispersion medium. Further, the upper limit is usually 20 MPa ^1/2 , and a substance above the upper limit may be better, but no substance exceeding 20 MPa ^{1/2 and} having a hydrogen bond term of 7 MPa ^1/2 or less is known.

  Examples of the dispersion medium that satisfies the above conditions include γ-butyrolactone, N-methylpyrrolidone, propylene carbonate, ethylene glycol sulfite, and acetonitrile. Of these, γ-butyrolactone, propylene carbonate, and ethylene glycol sulfite are particularly preferable.

  In the present invention, the substituted dispersion medium may be used alone or in combination of two or more. When mixing, the Hansen solubility parameter after mixing should just be in the said range. And when mixing 2 or more types, all may mix the dispersion medium in the range prescribed | regulated in this invention, or the dispersion medium in the range prescribed | regulated in this invention, and the dispersion medium outside a range May be mixed.

<Method for producing conductive substrate>
The method for producing a conductive substrate of the present invention comprises a step A in which the copper conductor ink of the present invention described above is applied on a substrate to form a coating layer and drying, and a conductive layer is formed by subjecting the dried coating layer to a conductive process. Step B is changed to Step B, and Step C is included between Step A and Step B, or after Step B, and thermosetting the thermosetting resin.
Below, the manufacturing method of this invention is explained in full detail.

(substrate)
In the production method of the present invention, the copper conductor ink is applied onto a substrate. Specific examples of the substrate material include polyimide, polyethylene naphthalate, polyethersulfone, polyethylene terephthalate, polyamideimide, and polyetherether. Films, sheets, and plates made of ketone, polycarbonate, liquid crystal polymer, epoxy resin, phenol resin, cyanate ester resin, fiber reinforced resin, inorganic particle filled resin, polyolefin, polyamide, polyphenylene sulfide, polypropylene, crosslinked polyvinyl resin, glass, ceramics, etc. Is mentioned.

[Step A]-Formation of coating layer-drying-
The coating layer can be formed by coating the copper conductor ink of the present invention described above on the substrate surface as a coating liquid and drying the resulting coating layer. The coating solution can be applied using a bar coater, comma coater, die coater, slit coater, gravure coater, ink jet coater or the like. The coating layer thickness is preferably 0.01 to 100 μm, more preferably 0.1 to 50 μm, and still more preferably 0.1 to 10 μm. The drying of the coating layer depends on the dispersion medium used and the coating layer thickness. For example, the substrate on which the coating layer is formed is placed on a hot plate at 80 to 150 ° C. for 5 to 30 minutes. It can be carried out. In addition, a known drying means can be employed. At this time, when the copper-based nanoparticles are copper / copper oxide core-shell particles and copper oxide particles, since the surfaces are both copper oxide, it is not necessary to dry in an atmosphere excluding oxygen like metal copper particles.

[Process B] -Conductive treatment-
Next, the dried coating layer is subjected to a conductor treatment. For example, the conductor treatment can be performed using a treatment liquid or a reducing liquid described below.

<Processing liquid>
The treatment liquid for treating and converting the coating layer configured as described above into a conductor is an agent that elutes a copper oxide component as a copper ion or a copper complex, and reduces the eluted copper ion or copper complex on the metal. It is a solution that essentially contains a reducing agent that precipitates in the solvent and a solvent that dissolves them, and does not contain copper ions. Below, each component is explained in full detail.

(Drug)
Any chemical agent that dissolves copper oxide by ionization or complex may be used. Basic nitrogen-containing compounds, salts of basic nitrogen-containing compounds, inorganic acids, inorganic acid salts, organic acids, organic acid salts, Lewis acids , Dioxime, dithizone, hydroxyquinoline, EDTA and at least one selected from the group consisting of β-diketones are preferred.
Among the above drugs, since most of the reducing agents are active on the base side, basic nitrogen-containing compounds are preferable, particularly amines and ammonia are preferable, and primary amines have high ability to dissolve copper oxides. Ammonia is more preferred.
As another example of the basic nitrogen-containing compound, the tertiary amine is preferably ethylenediamine tetraacetate, triethanolamine, or triisopanolamine.
Examples of the organic acid and organic acid salt include carboxylic acid and carboxylate, and among them, polyvalent carboxylic acid, polyvalent carboxylate, aromatic carboxylic acid, aromatic carboxylate, hydroxycarboxylic acid, hydroxycarboxylic acid Salts are preferable, and specifically, tartaric acid, phthalic acid, maleic acid, succinic acid, fumaric acid, salicylic acid, malic acid, citric acid, and salts thereof are preferable.
Dioximes include dimethylglyoxime, benzyldiglyoxime, 1,2-cyclohexanedione diglyoxime, β-diketone includes acetylacetone, and aminoacetic acid includes amino acids such as glycine.
As a density | concentration of the chemical | medical agent which ionizes or complexes copper oxide, 0.001-30 mol / L is preferable, 0.01-15 mol / L is more preferable, 0.1-8 mol / L is further more preferable. If it is less than 0.001 mol / L, the copper oxide may not be dissolved at a sufficient rate.

(Reducing agent)
Reducing agent is borohydride compound, aluminum hydride compound, alkylamine borane, hydrazine compound, aldehyde compound, phosphorous acid compound, hypophosphorous acid compound, ascorbic acid, adipic acid, formic acid, alcohol, tin (II) compound , Metal tin, and at least one selected from the group consisting of hydroxyamines can be suitably used. Particularly, dimethylamine borane (DMAB), hydrazine, formaldehyde, ascorbic acid and the like are preferable, and citric acid and the like are also preferable. Can be used.
As a density | concentration of the reducing agent used for a process liquid, 0.001-30 mol / L is preferable, 0.01-15 mol / L is more preferable, 0.01-10 mol / L is further more preferable. When the reducing agent concentration is less than 0.001 mol / L, metallic copper may not be generated at a sufficient rate.
In addition, when the molar ratio of the concentration of the agent that ionizes or complexes copper oxide and the concentration of the reducing agent is 5,000 or more, the concentration of copper ions that are liberated in the solution increases and copper is deposited outside the particle deposition portion. Therefore, it is not preferable.
As the solvent, a highly polar solvent is preferable because it is necessary to dissolve the above-described solubilizer, reducing agent, and copper ion or copper complex. Specifically, water, glycerin, and formamide can be used.
The treatment proceeds at room temperature, but the reaction may be accelerated or decelerated and heated or cooled as necessary to change the state of the resulting copper film (conductive layer). Further, in order to control the homogeneity and reaction rate of the copper film and foaming during the reaction, addition of additives, stirring, shaking of the substrate, and addition of ultrasonic waves may be performed.

<Treatment with treatment liquid>
The coating layer after drying formed as described above is treated with the treatment liquid. Specifically, the substrate on which the coating layer is formed is immersed in a container filled with the treatment liquid. Or by continuously spraying the treatment liquid onto the coating layer. In any case, the copper oxide in the coating layer is ionized or complexed by the agent in the treatment liquid, and then reduced to metallic copper by the reducing agent, so that the space between the particles can be filled with metallic copper. A conductive layer is formed.
The treatment time with the treatment liquid is appropriately set because it varies depending on the concentration and temperature of the treatment liquid. For example, the treatment time can be 0.5 to 6 hours, and the temperature can be from room temperature to 90 ° C.
The substrate on which the conductive layer is formed is exposed to ultrapure water or the like and then dried by air drying, hot plate, warm air drying, oven, or the like. At this time, in order to facilitate drying, acetone, methanol, ethanol, or the like may be applied to replace water with a solvent, followed by drying.
A conductive layer can be manufactured as described above.

<Conductive treatment with reducing liquid>
In the present invention, the conductor treatment can also be performed by immersing the substrate after applying the copper conductive ink in a heated reducing liquid.
As the reducing liquid, any liquid capable of reducing copper oxide and having a boiling point higher than the sintering temperature of copper may be used, for example, an organic compound having a primary or secondary hydroxyl group, a compound having a phenol group, Examples thereof include liquid organic compounds having a silicon hydride group, organic compounds having a primary or secondary amino group, phosphorous acid compounds, and hydrazine compounds. Further, a high boiling point solvent in which these compounds or a solid reducing substance is mixed may be used. As the organic solvent having a hydroxyl group, glycerin, ethylene glycol, propanediol, butanol, butanediol and the like are preferable. Examples of the reducing substance include ascorbic acid, citric acid, phosphite, tin (II) compound, borohydride compound, silicon hydride compound, aluminum hydride compound, and organic aluminum.

  By immersion in the reducing liquid as described above, the copper / copper oxide core-shell particles or the copper oxide particles in the coated and dried film are reduced to copper particles. As described above, the reducing liquid in this state is not heated, but may be appropriately heated for the purpose of promoting the progress of the reduction reaction. The temperature of the reducing liquid in this case is preferably room temperature to 200 ° C., and the holding time of the temperature varies depending on the thickness of the particle layer to be processed, the heat capacity of the substrate, the reducing agent, and the temperature, but it is 10 seconds to 60 seconds. Minutes are preferred.

[Step C]-Thermosetting-
The copper conductor ink of the present invention contains a thermosetting resin as described above, but in this step, the conductive layer (after step B) obtained by conducting the conductor is heated to produce the thermosetting resin. Cure the resin. At this time, since the volume of the thermosetting resin is set so that the thermosetting resin enters the voids between the copper-based nanoparticles, the contact between the copper-based nanoparticles is rarely disturbed, and the volume is low. Resistivity can be realized. On the other hand, the original adhesive function of the thermosetting resin can improve the adhesiveness between the substrate and the conductive layer, and can improve the mechanical strength of the conductive layer itself.
In addition, the said process C may be performed to the application layer after application | coating drying (between the process A and the process B), and even in that case, the adhesiveness of a board | substrate and a conductive layer finally, a conductive layer However, as described above, it is preferable to perform the step B after the step B because the volume resistivity becomes lower.

The heating temperature in step C is preferably 100 to 250 ° C, and more preferably 150 to 200 ° C. Further, the heating time varies depending on the heating temperature, and thus cannot be generally described. For example, when heating at a temperature of 175 ° C., it is preferably 5 to 60 minutes, more preferably 10 to 30 minutes. .
In this step, as a heating means, hot plate, hot air dryer, hot air heating furnace, nitrogen dryer, infrared dryer, infrared heating furnace, far infrared heating furnace, microwave heating device, laser heating device, electromagnetic heating An apparatus, a heater heating apparatus, a steam heating furnace, a hot plate press apparatus, or the like can be used.

By the above method for producing a conductive substrate of the present invention, a conductive substrate having a high adhesion between the conductive layer and the substrate and a high conductivity of the conductive layer can be produced.
That is, since the conductive substrate of the present invention is obtained by the method for producing a conductive substrate, it is a conductive substrate having high adhesion between the conductive layer and the substrate and high conductivity of the conductive layer.

<Copper wiring board manufacturing method>
By using the copper conductor ink of the present invention as an ink for drawing a wiring pattern on a substrate, a copper wiring substrate having high adhesion between the wiring and the substrate and high conductivity can be obtained. In particular, when the dynamic viscosity is set to 5 to 20 mPa · s as described above, it is excellent in ink jet aptitude, so that a copper wiring board can be manufactured by ink jet recording using the copper conductor ink.
Although the manufacturing method of a copper wiring board will be described below, the manufacturing method of the copper wiring board differs from the above-described manufacturing method of the conductive board of the present invention in the conductive layer and the wiring pattern, and other configurations. Since this is the same, only wiring pattern drawing will be described.

<Drawing of wiring pattern>
As a technique for drawing an arbitrary wiring pattern on the substrate using the copper conductor ink of the present invention, printing or coating conventionally used for applying ink can be used. In order to draw a wiring pattern, screen dispersion, jet printing, ink jet printing, transfer printing, offset printing, and dispenser can be used using the dispersion.

After drawing the wiring pattern as described above, the copper oxide in the wiring pattern is made conductive by treating the wiring pattern with the copper conductor ink in the same manner as in the method for manufacturing the conductive substrate of the present invention described above. A copper wiring board is manufactured by changing to metal copper and forming a conductor.
The process after drawing the wiring pattern is substantially the same as the method for manufacturing the conductive substrate of the present invention described above, and the “coating film” in the description of the method for manufacturing the conductive substrate of the present invention described above is The copper wiring board manufacturing method of the present invention corresponds to a “wiring pattern”.

  As a substrate used in the method for producing a copper wiring substrate, specifically, polyimide, polyethylene naphthalate, polyethersulfone, polyethylene terephthalate, polyamideimide, polyetheretherketone, polycarbonate, liquid crystal polymer, epoxy resin, phenol resin, Examples thereof include films, sheets and plates made of cyanate ester resin, fiber reinforced resin, polyolefin, polyamide, polyphenylene sulfide and the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

[Example 1]
(Preparation of resin-added copper-based nanoparticle dispersion)
10 g of copper oxide nanoparticles (average particle size 70 nm, manufactured by C.I. Kasei), laser ablation method copper nanoparticles (prototype, manufactured by Fukuda Metal Foil Powder Industry) 28 mass% of 35.7 g of γ-butyrolactone dispersion, and γ-butyrolactone 53 g, 0.6 g of bisphenol A novolac epoxy resin (N865 manufactured by Dainippon Ink and Chemicals), 0.43 g of a condensate of bisphenol F and dimethoxydiphenylsilane, and 2-ethyl-4-methylimidazole (manufactured by Wako Pure Chemical Industries, Ltd.) ) And 0.105 g of a 1 mass% γ-butyrolactone solution were weighed and dispersed with a homomixer at 8,000 rpm for 1 hour. Among these preparations, bisphenol A novolak epoxy resin, bisphenol F and dimethoxydiphenylsilane condensate, 2-ethyl-4-methylimidazole are resin components, and 29 vol% (5 mass%) is added to the copper-based particles. It was adjusted. The copper conductor ink of Example 1 was prepared as described above.
FIG. 2 shows the results of measuring the viscosity of the obtained copper conductor ink with a rheometer (Physica MCR301, manufactured by Anton Paar) using a cone plate (diameter 50 mm, angle 1 °). FIG. 2 is a graph showing the shear viscosity (dynamic viscosity) of the copper conductor inks prepared in Example 1 and Comparative Examples 2 and 4, but the copper conductor ink of Example 1 was not added with a resin component. Compared with Comparative Example 2 which is different from Example 1 only in respect, the difference in viscosity was hardly observed.

(Coating, drying)
The prepared copper conductor ink was applied to an epoxy substrate (trade name: MCL-679F, manufactured by Hitachi Chemical Co., Ltd.) having a copper pattern shown in FIG. Then, drying for 20 minutes, application and drying were repeated twice to obtain a substrate having a copper conductor ink coating layer.

(Conductor treatment)
The treatment liquid A for conductorization treatment was weighed according to Table 1. Place a substrate having a copper conductor ink coating layer on the bottom of the petri dish, place a small piece of glass on the edge so that the substrate does not float, pour the treatment liquid A and conduct a conductor, and apply a copper conductor ink coating layer Was changed to a conductive layer. As a result of treatment at room temperature (20 ° C.), the substrate having the resin-added copper-based nanoparticle coating layer that was initially black changed gradually to copper color with foaming, and bright copper luster after 5 hours (FIG. 3A). Although the figures are all black and white, the colors are actually as described above.

(Curing treatment of resin component)
The substrate having a copper conductor ink coating layer (conductive layer) subjected to the conductor treatment was heated on a hot plate at 175 ° C. for 30 minutes to cure the epoxy resin in the conductive layer. A conductive substrate was obtained as described above.

(Tape peeling test)
In the tape peeling test, cellotape (registered trademark) (Nichiban, trade name) was attached to the conductive layer side of the conductive substrate obtained as described above, and after being sufficiently adhered with a finger, it was peeled off. As a result, as shown in FIG. 4 (A), a small amount of powdery substance adhered to the adhesive surface of the cello tape (registered trademark), but the conductive layer did not peel from the substrate side, and 0.1Ω before tape peeling. The resistance was 0.2Ω, which was almost the same after the tape was peeled off. These results are summarized in Table 2.

[Example 2]
The resin component was treated in the same manner as in Example 1 except that the curing treatment was performed before the conductor treatment, and evaluation was performed in the same manner. As a result of the tape peeling test, as shown in FIG. 4 (B), the conductive layer does not peel from the substrate side although a small amount of powdery substance adheres to the adhesive surface of the cello tape (registered trademark). The resistance, which was 0.3Ω, was 18.4Ω after tape peeling (Table 2). FIG. 3B shows the copper conductor layer surface after the (resin component curing treatment) and (conducting treatment) of Example 2 were performed.

[Example 3]
45 g of copper oxide nanoparticles (average particle size 70 nm, manufactured by C.I. Kasei), 102 g of γ-butyrolactone, 1.5 g of bisphenol A novolac epoxy resin (N865 manufactured by Dainippon Ink and Chemicals), and bisphenol A novolak (VH-4170 large) Nippon Ink Chemical Co., Ltd.) 0.84 g and 2-ethyl-4-methylimidazole (manufactured by Wako Pure Chemical Industries, Ltd.) 1 mass% γ-butyrolactone solution 0.237 g were weighed, and homomixer at 8,000 rpm for 1 hour. Distributed. Among these preparations, bisphenol A novolac epoxy resin, bisphenol A novolac, and 2-ethyl-4-methylimidazole are resin components, and the volume was adjusted to 29 vol% (5 mass%) with respect to the copper-based particles. The copper conductor ink of Example 3 was prepared as described above.
The results of measuring the viscosity of the obtained copper conductor ink with a rheometer using a cone plate are shown in FIG. FIG. 5 shows the shear viscosity (dynamic viscosity) of the copper conductor inks prepared in Example 3 and Comparative Example 3, but the copper conductor ink of Example 3 was substantially implemented except that no resin component was added. Compared with Comparative Example 3 which was the same as Example 3, there was almost no difference in viscosity.
Thereafter, in the same manner as in Example 1, (application, drying), (conducting treatment), (curing treatment of resin component), and (tape peeling test) were performed.

[Examples 4 to 10]
The amount of resin added was 6 vol% (1 mass%) in Example 4, 11 vol% (2 mass%) in Example 5, 29 vol% (5 mass%) in Example 6, and 41 vol% (10 mass%) in Example 7. Example 8 (resin-added copper) was the same as Example 1 except that 55 vol% (16.4 mass%) was used, Example 9 was 68 vol% (25 mass%), and Example 10 was 82 vol% (41.2 mass%). Preparation of system nanoparticle dispersion), (coating, drying), (conducting treatment), (curing treatment of resin component), and (tape peeling test) were performed. These results are summarized in Table 3. In Table 3, the tape peel test was evaluated according to the following evaluation criteria. Moreover, the surface resistance before and after tape peeling is shown in FIG.
~Evaluation criteria~
○: No deposit on the tape side after tape peeling △: There is a deposit on a part of the tape after tape peeling ×: There is a deposit on the tape front after tape peeling

[Examples 11 to 17]
The amount of resin added was 6 vol% (1 mass%) in Example 11, 11 vol% (2 mass%) in Example 12, 29 vol% (5 mass%) in Example 13, and 41 vol% (10 mass%) in Example 14. Example 15 was 55 vol% (16.4 mass%), Example 16 was 68 vol% (25 mass%), Example 17 was 82 vol% (41.2 mass%), and (resin component curing) before (conducting treatment) (Preparation of resin added copper-based nanoparticle dispersion), (application, drying), (curing treatment of resin component), (conducting treatment), (tape peeling) Test). These results are summarized in Table 4. Moreover, the surface resistance before and after tape peeling is shown in FIG.

[Example 18]
(Preparation of resin-added copper-based nanoparticle dispersion)
10 g of copper oxide nanoparticles (average particle size 70 nm, manufactured by CI Chemical Co., Ltd.), 1.1 g of copper nanoparticles (prototype, manufactured by Nissin Engineering), 29.2 g of γ-butyrolactone, bisphenol A novolac epoxy resin (N865 large) 0.47 g of Nippon Ink Chemical Co., Ltd.), 0.26 g of bisphenol A novolak (VH-4170 manufactured by Dainippon Ink and Chemicals), and 1 mass% γ of 2-ethyl-4-methylimidazole (manufactured by Wako Pure Chemical Industries, Ltd.) -0.072 g of butyrolactone solution was weighed and dispersed with a homomixer at 8,000 rpm for 1 hour. Among these preparations, bisphenol A novolac epoxy resin, bisphenol A novolac, and 2-ethyl-4-methylimidazole are resin components, and adjustment was made to add 29 vol% (6 mass%) to the copper-based particles. The copper conductor ink of Example 18 was prepared as described above.

(Coating, drying)
The prepared copper conductor ink was applied to an epoxy substrate (trade name: MCL-679F, manufactured by Hitachi Chemical Co., Ltd.) on which the copper foil had been entirely etched with an applicator having a gap of 100 μm, and then was applied on a hot plate at 100 ° C. Partial drying was performed to obtain a substrate having a copper conductor ink coating layer.

(Conductor treatment)
The board | substrate which has a resin addition copper-type nanoparticle application layer of Example 18 was immersed in the glycerol bath heated at 150 degreeC, and the conductorization process was performed. As a result of performing the treatment for 20 minutes, the substrate having the resin-added copper-based nanoparticle coating layer that was initially black turned brown. The volume resistivity is measured using a surface shape measuring device (MM3000, manufactured by Ryoka System) on the surface resistance measured using a four-end needle surface resistance measuring device (Loresta, manufactured by Mitsubishi Chemical Corporation) It was stopped by multiplying the obtained film thickness. The volume resistivity was 6.5 × 10 ⁻⁶ Ω · m.

(Curing treatment of resin component)
The added epoxy resin was cured by heating the substrate having a resin-added copper-based nanoparticle coating layer that had been subjected to conductor treatment on a hot plate under a nitrogen stream at 175 ° C. for 30 minutes. A conductive substrate was obtained as described above.

(Tape peeling test)
In the tape peeling test, cellotape (registered trademark) (Nichiban, trade name) was attached to the conductive layer side of the conductive substrate obtained as described above, and after being sufficiently adhered with a finger, it was peeled off. As a result, although a small amount of powdery substance adhered to the adhesive surface of the cello tape (registered trademark), the conductive layer did not peel from the substrate side, and the volume resistivity was 7.8 × 10 ⁻⁵ Ω · m. .

[Comparative Example 1]
A copper conductor ink was prepared and a conductive substrate was prepared in the same manner as in Example 1 except that the resin component was not cured, and evaluation was performed in the same manner as in Example 1. As a result of the tape peeling test, as shown in FIG. 4C, it was confirmed that a large amount of the conductive layer adhered to the adhesive surface of the cello tape (registered trademark) and the substrate surface was exposed. Moreover, the resistance which was 0.1Ω before the tape peeling disappeared after the tape peeling (Table 2).

[Comparative Example 2]
The same treatment as in Example 1 was conducted except that no resin component was added. As a result of the tape peeling test, a large amount of copper layer adhered to the adhesive surface of the cello tape (registered trademark) [FIG. 4 (C)]. As a result, the resistance that was 0.1 Ω before the tape peeling disappeared after the tape peeling (Table 2).

[Comparative Example 3]
45 g of copper oxide nanoparticles (average particle size 70 nm, manufactured by C-I Kasei) and 105 g of γ-butyrolactone were weighed and dispersed with a homomixer at 8,000 rpm for 1 hour. The viscosity was measured with a rheometer.

[Comparative Example 4]
In the preparation of the resin-added copper-based nanoparticle dispersion liquid of Example 1, the same as in Example 1 except that dicyandiamide (Wako Pure Chemical Industries) was used instead of the condensate of bisphenol F and dimethoxydiphenylsilane among the resin components. A resin-added copper-based nanoparticle dispersion was prepared. As a result, the dispersion became a viscous paste, and the dynamic viscosity was higher than that of Comparative Example 2 to which no resin was added and Example 1 to which the resin was added, as shown in FIG. Furthermore, it showed strong thixotropy and was unsuitable as an inkjet ink.
From the experiment of adding amines such as triethylamine, ethylenediamine, dibutylamine, and triethylenetetramine to CuO nanoparticles, they showed the behavior of aggregating CuO nanoparticles, and amine compounds are used as curing agents for inkjet inks. Was unsuitable.

10 Substrate

Claims (9)

A copper conductor ink containing copper-based nanoparticles and a thermosetting resin before thermosetting,
The copper conductor ink is characterized in that the volume of the thermosetting resin is larger than 1/4 of the void volume when the copper-based nanoparticles are closely packed and smaller than the void volume.   The copper conductor ink according to claim 1, wherein the thermosetting resin is contained in an amount of 6 to 29 vol% with respect to the volume of the copper-based nanoparticles.   The copper conductor ink according to claim 1, wherein the dynamic viscosity at 25 ° C. is 5 to 20 mPa · s.   The copper-based nanoparticles are composed of particles having a core / shell structure in which a core portion is copper and a shell portion is copper oxide, and / or copper oxide particles. The copper conductor ink according to item 1.   The thermosetting resin is at least one selected from the group consisting of an epoxy resin, an isocyanate resin, a phenol resin, a resol resin, and a siloxane resin. The copper conductor ink described in 1. 6. A dispersion medium having a hydrogen bond term in the Hansen solubility parameter of 8 MPa ^1/2 or less and a polar term in the Hansen solubility parameter of 11 MPa ^1/2 or more is used as the dispersion medium. The copper conductor ink according to any one of the above.   The copper conductor ink according to claim 6, which is prepared without using a dispersant for the copper-based nanoparticles. A process A in which the copper conductor ink according to any one of claims 1 to 7 is applied onto a substrate to form a coating layer and dried;
Step B for converting the dried coating layer into a conductive layer by conducting a conductive treatment;
Step C for thermosetting the thermosetting resin between Step A and Step B or after Step B;
The manufacturing method of the electroconductive board | substrate characterized by the above-mentioned.   A conductive substrate manufactured by the method for manufacturing a conductive substrate according to claim 8.