WO2016031404A1

WO2016031404A1 - Composition for electrically conductive film formation use, and method for producing electrically conductive film using same

Info

Publication number: WO2016031404A1
Application number: PCT/JP2015/069928
Authority: WO
Inventors: 美里佐々田; 秀樹松本
Original assignee: 富士フイルム株式会社
Priority date: 2014-08-28
Filing date: 2015-07-10
Publication date: 2016-03-03
Also published as: JPWO2016031404A1

Abstract

The purpose of the present invention is to provide: a composition for electrically conductive film formation use, from which an electrically conductive film that does not undergo the occurrence of defects and has excellent electrical conductivity can be formed; and a method for producing an electrically conductive film using the composition for electrically conductive film formation use. The present invention relates to: a composition for electrically conductive film formation use, which contains at least copper (II) oxide nanoparticles and a polyol-type organic solvent having a boiling point of 190 to 340ºC, wherein the ratio of an absorbance of the composition as measured at a wavelength of 400 nm with a spectrophotometer to an absorbance of the composition as measured at a wavelength of 600 nm with the spectrophotometer meets the requirement expressed by formula 1 shown below; and a method for producing an electrically conductive film using the composition for electrically conductive film formation use. Formula 1: 5 > α1/α2 > 3 In formula 1, α1 represents an absorbance of the composition as measured at a wavelength of 400 nm and α2 represents an absorbance of the composition as measured at a wavelength of 600 nm.

Description

Conductive film forming composition and method for producing conductive film using the same

The present invention relates to a composition for forming a conductive film and a method for producing a conductive film using the same.

As a method of forming a metal film on a base material, a metal film or a circuit board is obtained by applying a dispersion of metal particles or metal oxide particles to the base material by a printing method and then sintering by heat treatment or light irradiation treatment. A technique for forming an electrically conductive portion such as a wiring in is known.
Since the above method is simpler, energy-saving, and resource-saving than conventional high-heat / vacuum processes (sputtering) and plating processes, it is highly anticipated in the development of next-generation electronics.

For example, Patent Document 1 discloses a method of manufacturing a metallized ceramic substrate by firing a conductive metal particle component in a vacuum or in an inert atmosphere to form a conductor layer. In Patent Document 1, cupric oxide nanoparticles (manufactured by CI Kasei Co., Ltd., average particle size 48 nm) are specifically used as the conductive metal particles.

JP 2008-109062 A

On the other hand, in recent years, in order to meet the demand for miniaturization and high functionality of electronic devices, wirings are further miniaturized and highly integrated. Along with this, there is a demand for further improvement in the conductive characteristics of metal wiring.
From the viewpoint of productivity, a method for producing a conductive film by light irradiation is desired.
The present inventors prepared a conductive film by light irradiation using a composition containing a metal oxide (cupric oxide nanoparticles (manufactured by C-I Kasei Co., Ltd., average particle size 48 nm)) described in Patent Document 1. As a result, the conductivity of the obtained conductive film did not reach the level required recently, and further improvement was required.
In addition, when such a composition is applied onto a resin substrate to form a coating film, and light irradiation treatment is performed on the coating film, gas generated from the resin substrate, ablation of the composition, etc. There was also a problem that defects such as cracks were likely to occur in the conductive film.

An object of this invention is to provide the composition for electrically conductive film formation which suppresses generation | occurrence | production of a defect and can form the electrically conductive film which shows the outstanding electroconductivity in view of the said situation.
Another object of the present invention is to provide a method for producing a conductive film using the composition for forming a conductive film.

As a result of earnest research to solve the above problems, the present inventors contain cupric oxide nanoparticles and a polyol-based organic solvent having a boiling point in a predetermined range, and at a specific wavelength measured by a spectrophotometer. It has been found that the above problem can be solved by using a composition having an absorbance ratio in a predetermined range.
That is, it has been found that the above object can be achieved by the following configuration.

[1] Cupric oxide nanoparticles,
A composition for forming a conductive film, comprising at least a polyol organic solvent having a boiling point of 190 to 340 ° C.,
The composition for electrically conductive film formation in which the ratio of the light absorbency in wavelength 400nm and wavelength 600nm measured with the spectrophotometer satisfy | fills the following formula | equation 1.
Formula 1 5> α1 / α2> 3
In Formula 1, α1 represents the absorbance of the composition at a wavelength of 400 nm, and α2 represents the absorbance of the composition at a wavelength of 600 nm.
[2] The composition for forming a conductive film according to [1], wherein the average primary particle diameter of the cupric oxide nanoparticles is 2 to 25 nm.
[3] The composition for forming a conductive film according to [1] or [2], further comprising a polyoxyalkylene compound having a weight average molecular weight of 1,000 or more.
[4] The composition for forming a conductive film according to [3], wherein the polyoxyalkylene compound is polyethylene glycol.
[5] The ratio of particles having a particle size of 200 nm or more in the cumulative volume particle size distribution of cupric oxide nanoparticles measured by a dynamic light scattering method is 15% or less of the whole cupric oxide nanoparticles. The composition for forming a conductive film according to any one of [1] to [4].
[6] Further, an alcohol organic solvent or a ketone organic solvent having a surface tension of 40 mN / m or less and a boiling point of 50 to 180 ° C. is contained,
The composition for forming a conductive film according to any one of [1] to [5], wherein the content of the alcohol organic solvent or the ketone organic solvent is 1 to 50% by mass relative to the total mass of the composition object.
[7] The conductive film formation according to any one of [1] to [6], wherein the mass ratio of the cupric oxide nanoparticles to the polyol-based organic solvent is 1: 0.005 to 1: 2. Composition.
[8] The mass ratio between cupric oxide nanoparticles and the polyoxyalkylene compound is 1: 0.01 to 1: 0.5, according to any one of [3] to [7] A composition for forming a conductive film.
[9] The composition for forming a conductive film according to any one of [1] to [8], wherein the polyol organic solvent is a diol or a triol.
[10] The organic solvent according to any one of [1] to [9], wherein the polyol organic solvent is at least one selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, trimethylolpropane, and glycerin. A composition for forming a conductive film.
[11] Further, a metal catalyst is contained,
The composition for forming a conductive film according to any one of [1] to [10], wherein the mass ratio of the cupric oxide nanoparticles to the metal catalyst is 1: 0.001 to 1: 0.1. .
[12] The composition for forming a conductive film according to any one of [1] to [11], wherein α1 / α2 is greater than 4 and less than 5.
[13] Any of [1] to [12], wherein cupric oxide nanoparticles are produced by a wet method, and the average primary particle diameter of cupric oxide nanoparticles is 2 to 25 nm. The composition for electrically conductive film formation as described in any one.
[14] A step of applying the composition for forming a conductive film according to any one of [1] to [13] onto a resin substrate to form a coating film;
A process for producing a conductive film, comprising: subjecting a coating film to light irradiation treatment and forming a conductive film containing metal copper by reducing cupric oxide nanoparticles.

ADVANTAGE OF THE INVENTION According to this invention, the composition for electrically conductive film formation which can suppress generation | occurrence | production of a defect and can form the electrically conductive film which shows the outstanding electroconductivity can be provided.
Moreover, according to this invention, the manufacturing method of the electrically conductive film using this composition for electrically conductive film formation can also be provided.

Below, the suitable aspect of the manufacturing method of the composition for electrically conductive film formation of this invention and an electrically conductive film is explained in full detail.
In this specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
Moreover, in this specification, when a component contains 2 or more types of compounds, content of the said component refers to content of the sum total of 2 or more types of compounds.

[Composition for forming conductive film]
First, the composition for forming a conductive film of the present invention will be described.
The composition for forming a conductive film of the present invention comprises:
(A) cupric oxide nanoparticles,
(B) a conductive film forming composition containing at least a polyol organic solvent having a boiling point of 190 to 340 ° C.,
It is a composition for electrically conductive film formation in which the ratio of the light absorbency in wavelength 400nm and wavelength 600nm measured with the spectrophotometer satisfy | fills the following formula | equation 1.
Formula 1 5> α1 / α2> 3
In Formula 1, α1 represents the absorbance of the composition at a wavelength of 400 nm, and α2 represents the absorbance of the composition at a wavelength of 600 nm.

It is thought that the composition for forming a conductive film of the present invention can form a conductive film exhibiting excellent conductivity by suppressing the occurrence of defects by having α1 / α2 in a specific range.
In the present invention, α1 / α2 is presumed to be related to the dispersibility of (A) cupric oxide nanoparticles in the conductive film forming composition. When α1 / α2 is within the above range, (A) cupric oxide nanoparticles have a small primary particle size and are excellent in dispersibility in the conductive film forming composition. It is presumed that, as the surface area of the nanoparticles increases, the reaction points are exposed on the surface of the (A) cupric oxide nanoparticles, and the reaction probability between the reaction points and the reducing agent increases. Further, it is considered that the conductivity is increased by forming a dense conductor by promoting the fusion of particles.
In general, when the temperature applied to the resin substrate is high when forming the conductive film, gas is generated from the resin substrate, and the gas may cause cracks in the conductive film. In the present invention, when the surface area of the (A) cupric oxide nanoparticles is increased, the reaction between the (A) cupric oxide nanoparticles and the reducing agent can occur in a short time at a low temperature. In addition, the heat applied to the resin base material can be reduced. Therefore, generation | occurrence | production of the gas from a resin base material, melting | fusing and a deformation | transformation of a resin base material can be suppressed, and generation | occurrence | production of the crack of an electrically conductive film can be suppressed, As a result, it is thought that it is excellent in electroconductivity.

<(A) Cupric oxide nanoparticles>
The composition for forming a conductive film contains (A) cupric oxide nanoparticles. (A) Cupric oxide nanoparticles are reduced by a light irradiation treatment described later and constitute metallic copper in the conductive film.
The “cupric oxide” in the present invention is a compound that does not substantially contain copper that has not been oxidized. Specifically, in crystal analysis by X-ray diffraction, a peak derived from cupric oxide is detected. And a compound in which no metal-derived peak is detected. Although not containing copper substantially, it means that content of copper is 1 mass% or less with respect to (A) cupric oxide nanoparticles.

The ratio of particles having a particle diameter of 200 nm or more in the cumulative volume particle size distribution of the cupric oxide nanoparticles (A) in the conductive film forming composition measured by the dynamic light scattering method is the conductivity of the formed conductive film. It is preferably 15% or less of the whole cupric oxide nanoparticles, more preferably 10% or less, and even more preferably 5% or less from the viewpoint that the properties are more excellent and the occurrence of defects can be further suppressed. . Although a minimum in particular is not restrict | limited, 0% is mentioned.

Furthermore, (A) The ratio of the particles having a particle size of more than 0 nm and less than 100 nm in the cumulative volume particle size distribution measured by the dynamic light scattering method of cupric oxide nanoparticles is more conductive in the formed conductive film. From the standpoint of being excellent and capable of suppressing the occurrence of defects, it is preferably 50 to 100%, more preferably 65 to 100%, of the whole (A) cupric oxide nanoparticles.

The 50% particle size (D50) of the cupric oxide nanoparticles (A) in the composition for forming a conductive film of the present invention is more excellent in the conductivity of the formed conductive film and can further suppress the occurrence of defects. 20 to 150 nm is preferable, and 20 to 100 nm is more preferable. The 50% particle diameter is a cumulative volume particle size distribution of cupric oxide nanoparticles measured by a dynamic light scattering method. The cumulative amount when the relative particle amount is integrated from the small particle size side is 50%. The particle size.

The particle diameter and 50% particle diameter of (A) cupric oxide nanoparticles in the conductive film forming composition of the present invention can be measured by a dynamic light scattering method. More specifically, the measurement is performed using a nanotrack particle size distribution analyzer UPA-EX150 (manufactured by Nikkiso Co., Ltd.).
For the measurement of the dynamic light scattering method, the composition for forming a conductive film of the present invention can be used as it is or diluted with water or the like. It is preferable to carry out the measurement in a range where the concentration of cupric oxide nanoparticles in the composition is 0.01 to 0.1% by mass. When the concentration of cupric oxide nanoparticles in the composition is too high, the sample for measurement may be prepared by diluting with water or the like.

The method for controlling the particle diameter and 50% particle diameter of the (A) cupric oxide nanoparticles in the composition for forming a conductive film of the present invention is not particularly limited. Methods for controlling the type of copper nanoparticles and dispersant, methods for controlling the mixing conditions (mixing method, mixing procedure) of the dispersant and (A) cupric oxide nanoparticles, the disperser used, and the dispersion time A known method such as a method of changing (A) or a method of controlling the mixing ratio of cupric oxide nanoparticles and a solvent (water) is selected.

(A) The average primary particle diameter of the cupric oxide nanoparticles is preferably 2 to 40 nm, more preferably 2 to 25 nm, from the viewpoint that the conductivity of the conductive film to be formed is more excellent and defects can be further suppressed. 2 to 20 nm is more preferable, and 5 to 15 nm is particularly preferable.
Note that the average primary particle diameter is at least 400 (A) oxidized by observation with a transmission electron microscope (abbreviation of TEM: Transmission Electron Microscope) or scanning electron microscope (abbreviation of Scanning Electron Microscope). Measure the equivalent circle diameters of the cuprous nanoparticles and calculate them by arithmetic averaging. The equivalent circle diameter means the diameter of a circle corresponding to the same area as the observed two-dimensional shape of the cupric oxide nanoparticles (A).

(A) The average primary particle diameter and 50% particle diameter of cupric oxide nanoparticles are 50% particle diameter / average 1 in that the conductivity of the formed conductive film is more excellent and the generation of defects can be further suppressed. The ratio of the next particle diameter is preferably 2 to 75, more preferably 2 to 50, and most preferably 2 to 20.

In addition, (A) Cupric oxide nanoparticles may use a commercial item, or may be manufactured with a well-known manufacturing method.
(A) As a manufacturing method of cupric oxide nanoparticles, for example, there are a method of performing granulation in a gas phase (gas phase method) and a method of performing granulation in a wet state (wet method). (A) The cupric oxide nanoparticles are preferably produced by a wet method. It is because it becomes possible to control to a desired particle shape by granulating by a wet method.
(A) For the synthesis of cupric oxide nanoparticles, for example, as described in JP-A No. 2003-183024, etc., a divalent salt such as copper nitrate is reacted with a base to produce hydroxylation. A method of producing copper and granulating copper oxide by heat dehydration is preferred. According to this method, it is possible to synthesize cupric oxide nanoparticles (A) at a lower temperature and in a shorter time, and the desired particle shape / distribution can be controlled.
When granulating by a wet method, it is preferable to use water or a polyhydric alcohol having a boiling point of 150 to 300 ° C. as a solvent. It is preferable because it does not volatilize during heating and dehydration and is excellent in dispersion stability of the prepared cupric oxide nanoparticles.

The content of cupric oxide nanoparticles in the composition for forming a conductive film of the present invention is not particularly limited, but it is easy to prepare a predetermined composition, and the characteristics (defect suppression, conductivity) of the formed conductive film are From the standpoint of superiority, it is preferably 3 to 80% by mass, more preferably 10 to 60% by mass, based on the total mass of the composition.

<(B) Polyol organic solvent>
(B) The composition for forming a conductive film of the present invention contains a polyol organic solvent and has a boiling point of 190 to 340 ° C. In addition, the said boiling point is a thing under 1 atmosphere.
The polyol organic solvent is not particularly limited as long as it is a compound having two or more hydroxy groups in one molecule.
(B) The polyol organic solvent can function as a so-called reducing agent.

(B) Examples of polyol organic solvents include diols; trifunctional or higher functional polyols such as 1,2,3-butanetriol, erythritol, pentaerythritol, trimethylolpropane, and glycerin (alcohols having three or more hydroxy groups). ). (B) The polyol-based organic solvent is preferably diol or triol.
Examples of the diol include alcohols having two hydroxy groups such as ethylene glycol and 2,3-butanediol; dialkylene glycols such as diethylene glycol; trialkylene glycols such as triethylene glycol. When polyalkylene glycol such as dialkylene glycol and trialkylene glycol is used as the diol, it is mentioned as one of preferred embodiments that its weight average molecular weight is less than 1,000.
Among them, the diol is preferably at least one selected from the group consisting of ethylene glycol, diethylene glycol and triethylene glycol.
The triol is preferably trimethylolpropane or glycerin.

The boiling point of the (B) polyol-based organic solvent is 190 to 340 ° C., and is preferably 200 to 300 ° C. from the viewpoint that the conductive film to be formed is more excellent in conductivity and the generation of defects can be further suppressed. .
When the boiling point is less than 190 ° C., the conductivity of the conductive film formed is inferior and many defects are generated. Moreover, when the boiling point is higher than 340 ° C., the conductivity of the formed conductive film is inferior.

(A) The mass ratio of cupric oxide nanoparticles and (B) polyol-based organic solvent is sufficient in reducing power, more excellent in conductivity of the conductive film formed, and more capable of suppressing the occurrence of defects. It is preferably 1: 0.005 to 1: 2, more preferably 1: 0.005 to 1: 1, and still more preferably 1: 0.005 to 1: 0.5.

((C) polyoxyalkylene compound)
The composition for forming a conductive film of the present invention may further contain (C) a polyoxyalkylene compound having a weight average molecular weight of 1,000 or more. In this case, it is preferable from the viewpoint that the conductivity of the conductive film to be formed is more excellent and the occurrence of defects can be further suppressed.
Examples of the (C) polyoxyalkylene compound include polyethylene glycol and polypropylene glycol, and polyethylene glycol is preferable.

(C) The weight average molecular weight of the polyoxyalkylene compound is preferably 4,000 or more, more preferably from 8,000 to 500, from the viewpoint that the conductivity of the formed conductive film is more excellent and the occurrence of defects can be further suppressed. More preferably, it is 1,000.
(C) The weight average molecular weight of the polyoxyalkylene compound is a polystyrene equivalent value obtained by GPC (gel permeation chromatography, abbreviation for Gel Permeation Chromatography) method (solvent: N-methylpyrrolidone).

The mass ratio of (A) cupric oxide nanoparticles and (C) polyoxyalkylene compound is 1: 0.01 to 1 from the viewpoint that the conductivity of the conductive film to be formed is better and the generation of defects can be further suppressed. : 0.5 is preferable, and 1: 0.02 to 1: 0.4 is more preferable.

((D) alcohol-based organic solvent or ketone-based organic solvent)
The composition for forming a conductive film of the present invention can further contain an alcohol organic solvent or a ketone organic solvent (D) having a surface tension of 40 mN / m or less and a boiling point of 50 to 180 ° C. In this case, excellent printability can be obtained.
The surface tension is measured by a measurement method using a dropping method under the condition of 20 ° C.
Examples of the alcohol organic solvent or ketone organic solvent (D) include ethanol (boiling point 78.37 ° C., surface tension 22.55 mN / m), 1-butanol (boiling point 117 ° C., surface tension 26 mN / m), and the like. Alcohol-based organic solvents: ketone-based organic solvents such as methyl ethyl ketone (boiling point 79.5 ° C., surface tension 24.6 mN / m), acetone (boiling point 56.5 ° C., surface tension 23.3 mN / m), and the like.
The surface tension of the alcohol-based organic solvent or the ketone-based organic solvent (D) is preferably 20 to 40 mN / m from the viewpoint that the conductivity of the conductive film to be formed is more excellent and defects can be further suppressed. More preferably, it is ˜30 mN / m.
The boiling point of the alcohol-based organic solvent or the ketone-based organic solvent (D) is preferably 50 to 180 ° C. from the viewpoint that the conductivity of the conductive film to be formed is better and the generation of defects can be further suppressed, and 70 to 150 ° C. More preferably, the temperature is 70 ° C., and more preferably 70 to 120 ° C.

The amount of the alcohol-based organic solvent or the ketone-based organic solvent (D) is preferably 1 to 50% by mass, more preferably 1 to 45% by mass in the composition for forming a conductive film. More preferably, it is mass%.

((E) Metal catalyst)
The composition for forming a conductive film of the present invention can further contain (E) a metal catalyst.
The metal catalyst (E) preferably contains at least one metal element (metal) selected from the group consisting of groups 8 to 11 of the periodic table. The metal element is at least one metal element selected from the group consisting of gold, silver, copper, platinum, palladium, rhodium, iridium, ruthenium, osmium, and nickel in that the conductivity of the conductive film is more excellent. Preferably, it is at least one metal element selected from the group consisting of silver, platinum, palladium, and nickel, more preferably palladium or platinum, and most preferably palladium. That is, the metal catalyst (E) is preferably a metal catalyst containing palladium because the conductivity of the obtained conductive film is more excellent.

As a suitable aspect of a metal catalyst (E), palladium salt and a palladium complex are mentioned, for example. Of these, a palladium salt is preferable.
The kind of palladium salt is not particularly limited, and specific examples thereof include palladium hydrochloride, nitrate, sulfate, carboxylate, sulfonate, phosphate, phosphonate and the like. Of these, carboxylate is preferable.
The number of carbon atoms of the carboxylic acid forming the carboxylate is not particularly limited, but is preferably 1 to 10, and more preferably 1 to 5. The carboxylic acid forming the carboxylate may have a halogen atom (preferably a fluorine atom).

The metal catalyst (E) is preferably at least one compound selected from the group consisting of palladium acetate, palladium trifluoroacetate and tetrakis (triphenylphosphine) palladium, and more preferably palladium acetate.

(A) The mass ratio of cupric oxide nanoparticles and (E) metal catalyst is such that α1 / α2 is in a more appropriate range. (A) Dispersibility of cupric oxide nanoparticles is excellent. From the viewpoint of more excellent electrical conductivity and further suppressing the occurrence of defects, the ratio is preferably 1: 0.001 to 1: 0.1, more preferably 1: 0.001 to 1: 0.05.

(water)
The composition for electrically conductive film formation can contain water further. Water functions as a dispersion medium for (A) cupric oxide nanoparticles. Use of water as a solvent is preferable because of its excellent safety.
As water, what has the purity of the level of ion-exchange water is preferable.
The water content can be 1 to 90% by mass with respect to the total mass of the conductive film-forming composition.

(Other ingredients)
The composition for forming a conductive film can further contain components other than (A) to (E) and water. Examples of components other than the above include additives such as water-soluble polymers, surfactants, and thixotropic agents. The kind and amount of the additive can be appropriately selected within a range that does not hinder the object and effect of the present invention.

The manufacturing method in particular of the composition for electrically conductive film formation is not restrict | limited, A well-known method is employable.
Especially, (A) cupric oxide nanoparticle mentioned above, (B) polyol type organic solvent, and other arbitrary components which can be used as needed are mixed, and the composition for electrically conductive film formation is manufactured. it can.
The mixing method is not particularly limited. For example, a homogenizer (for example, an ultrasonic homogenizer, a high-pressure homogenizer), a mill (for example, a bead mill, a ball mill, a tower mill, a three roll mill), a mixer (for example, a planetary mixer, a disper mixer, a hen) Examples thereof include a method of mixing and dispersing using a sill mixer, a kneader, a Clare mix, a self-revolving mixer (stirring deaerator), and the like. Among these, it is preferable to use an ultrasonic homogenizer or a bead mill because the dispersibility of cupric oxide nanoparticles is more excellent.

<Characteristics of conductive film forming composition>
About the composition for electrically conductive film formation, ratio of the light absorbency in wavelength 400nm and wavelength 600nm measured with the spectrophotometer satisfy | fills the following formula | equation 1.
Formula 1 5> α1 / α2> 3
In Equation 1, α1 represents absorbance at a wavelength of 400 nm, and α2 represents absorbance at a wavelength of 600 nm.
α> α2 is preferably 5> α1 / α2> 4 from the viewpoint that the conductivity of the conductive film to be formed is more excellent and defects can be further suppressed.

Measurement with a spectrophotometer (ultraviolet-visible absorption spectrum measurement) is performed using an ultraviolet-visible spectrophotometer (UV-2450, manufactured by Shimadzu Corporation).
At that time, the measurement is performed in the range where the concentration of cupric oxide nanoparticles in the composition is 0.0005 to 0.1 mass%. When the concentration of cupric oxide nanoparticles in the composition is too high, the sample for measurement may be prepared by diluting with water.
From the ultraviolet-visible absorption spectrum obtained by the above measurement, the absorbance at a wavelength of 400 nm and the absorbance at a wavelength of 600 nm are measured, and applied to the above equation 1 to calculate the ratio (α1 / α2).

In addition, the control method in particular of (alpha) 1 / (alpha) 2 of the composition for electrically conductive film formation of this invention is not restrict | limited. Since α1 / α2 is thought to be greatly influenced by the state of cupric oxide nanoparticles, as a method for controlling α1 / α2, for example, as described above, the average primary particle diameter of particles is controlled within a predetermined range. And a method of controlling the aggregation state (so-called control of particle size distribution of cupric oxide nanoparticles in the composition for forming a conductive film of the present invention).

[Method for producing conductive film]
Next, the manufacturing method of the electrically conductive film of this invention is demonstrated below.
The method for producing the conductive film of the present invention comprises:
A step of applying the composition for forming a conductive film of the present invention on a resin base material to form a coating film (hereinafter also referred to as a coating film forming step as appropriate);
Performing a light irradiation treatment on the coating film, and reducing the cupric oxide nanoparticles to form a conductive film containing metallic copper (hereinafter also referred to as a conductive film forming process). It is a manufacturing method.
Below, each process is explained in full detail.

<Coating film formation process>
This step is a step of applying the above-described composition for forming a conductive film on a resin substrate to form a coating film. The precursor film before the reduction treatment is obtained in this step.
The composition for forming a conductive film used is as described above.

Examples of the resin base material include polyolefin resins such as low density polyethylene resin, high density polyethylene resin, polypropylene, and polybutylene; methacrylic resins such as polymethyl methacrylate; polystyrene, acrylonitrile butadiene styrene copolymer (ABS), Polystyrene resin such as acrylonitrile styrene copolymer (AS); acrylic resin; polyester resin (polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, poly 1,4-cyclohexyldimethylene terephthalate, etc.); nylon resin and nylon copolymer Polyamide resin selected from: Polyvinyl chloride resin; Polyoxymethylene resin; Polycarbonate resin; Polyphenylene sulfide resin; Modified polypheny Polyether resin; Polysulfone resin; Polyethersulfone resin; Polyketone resin; Polyethernitrile resin; Polyetheretherketone resin; Polyetherimide resin, Polyetherketone resin, Polyetherketoneketone resin; Polyimide resin; Polyamideimide resin A fluororesin; a resin substrate such as a cellulose derivative. Among these, a polyester resin base material, a polycarbonate resin base material, a polyimide resin base material, and a polyetherimide resin base material are preferably used.

The method in particular of apply | coating the composition for electrically conductive film formation on a resin base material is not restrict | limited, A well-known method is employable. For example, coating methods such as a screen printing method, a dip coating method, a spray coating method, a spin coating method, and an ink jet method can be used.
The shape of application is not particularly limited, and may be a planar shape covering the entire surface of the resin base material or a pattern shape (for example, a wiring shape or a dot shape).
What is necessary is just to adjust suitably as an application quantity of the composition for electrically conductive film formation on the resin base material according to the film thickness of the electrically conductive film desired. Usually, the thickness of the coating film is preferably 0.01 to 5000 μm, more preferably 0.1 to 1000 μm, and further preferably 1 to 100 μm.

In this step, if necessary, the conductive film-forming composition may be applied to the resin substrate and then dried to remove the solvent. By removing the remaining solvent, it is possible to suppress the generation of minute cracks and voids due to the vaporization and expansion of the solvent in the conductive film forming step described later. It is preferable in terms of adhesion.
A warm air dryer or the like can be used as a method for the drying treatment. The temperature for the drying treatment is preferably 40 ° C. to 200 ° C., more preferably 50 ° C. or more and less than 150 ° C., and further preferably 50 ° C. to 120 ° C.
The drying time is not particularly limited, but it is preferably 10 seconds to 60 minutes because the adhesion between the resin substrate and the conductive film becomes better.

<Conductive film formation process>
This step is a step of performing a light irradiation treatment on the coating film formed in the coating film forming step to form a conductive film containing metallic copper.
By performing the light irradiation treatment, (A) cupric oxide nanoparticles are reduced and further fused to obtain metallic copper. More specifically, (A) cupric oxide nanoparticles are reduced to form metallic copper particles, the produced metallic copper particles are fused together to form grains, and the grains are bonded and fused together. Thus, a conductive thin film containing copper is formed.

Light irradiation treatment enables reduction and sintering to metallic copper by irradiating light at a room temperature to a portion to which a coating film has been applied for a short time, and causes deterioration of the resin base material due to prolonged heating. Therefore, the adhesion of the conductive film to the resin base material becomes better.

The light source used in the light irradiation treatment is not particularly limited, and examples thereof include a mercury lamp, a metal halide lamp, a xenon lamp, a chemical lamp, and a carbon arc lamp. Examples of radiation include electron beams, X-rays, ion beams, and far infrared rays. Further, g-line (wavelength 436 nm), i-line (wavelength 365 nm), deep ultraviolet light (Deep-UV light), and high-density energy beam (laser beam) are also used.
Specific examples of preferred embodiments include scanning exposure with an infrared laser, high-illuminance flash exposure such as a xenon discharge lamp, and infrared lamp exposure.

The light irradiation is preferably light irradiation with a flash lamp, and more preferably pulsed light irradiation (eg, pulsed light irradiation with a xenon (Xe) flash lamp). Irradiation with high-energy pulsed light can concentrate and heat the surface of the portion to which the coating film has been applied in a very short time, so that the influence of heat on the resin substrate can be extremely reduced.
The irradiation energy of the pulsed light is preferably 1 to 100 J / cm ^{2 and} more preferably 1 to 30 J / cm ² . The pulse width is preferably 1 μsec to 100 msec, and more preferably 10 μsec to 10 msec. The irradiation interval of the pulsed light is preferably 1 msec to 10 seconds, more preferably 1 second to 10 seconds, and further preferably 1 to 5 seconds.

The atmosphere for performing the light irradiation treatment is not particularly limited, and examples thereof include an air atmosphere, an inert atmosphere, and a reducing atmosphere. Note that the inert atmosphere refers to an atmosphere filled with an inert gas such as argon, helium, neon, or nitrogen. The reducing atmosphere refers to an atmosphere in which a reducing gas such as hydrogen or carbon monoxide exists.

<Conductive film>
By carrying out the above steps, a conductive film (metal copper film) containing metal copper is obtained.
The film thickness of the conductive film is not particularly limited, and an optimum film thickness is appropriately adjusted according to the intended use. Of these, 0.01 to 1000 μm is preferable and 0.1 to 100 μm is more preferable from the viewpoint of printed wiring board use.
The film thickness is a value (average value) obtained by measuring three or more thicknesses at arbitrary points on the conductive film and arithmetically averaging the values.
The volume resistivity of the conductive film is preferably less than 1000 μΩ · cm, more preferably less than 300 μΩ · cm, and even more preferably less than 100 μΩ · cm from the viewpoint of conductive characteristics.
The volume resistivity can be calculated by measuring the surface resistance value of the conductive film by the four-probe method and then multiplying the obtained surface resistance value by the film thickness.

The conductive film may be provided, for example, on the entire surface of the resin base material or in a pattern. The patterned conductive film is useful as a conductor wiring (wiring) such as a printed wiring board.
As a method for obtaining a patterned conductive film, for example, a method of applying the above-mentioned composition for forming a conductive film to a resin base material in a pattern and performing the light irradiation treatment, or a conductive material provided on the entire surface of the resin base material. For example, a method of etching the film into a pattern may be used.
The etching method is not particularly limited, and for example, a known subtractive method or semi-additive method can be employed.

When a patterned conductive film is configured as a multilayer wiring board, an insulating layer (insulating resin layer, interlayer insulating film, solder resist) is further laminated on the surface of the patterned conductive film, and further wiring (metal) is formed on the surface. Pattern) may be formed.

The material of the insulating film is not particularly limited. For example, epoxy resin, glass epoxy resin, aramid resin, crystalline polyolefin resin, amorphous polyolefin resin, fluorine-containing resin (polytetrafluoroethylene, perfluorinated polyimide, perfluorinated) Amorphous resin), polyimide resin, polyether sulfone resin, polyphenylene sulfide resin, polyether ether ketone resin, liquid crystal resin, and the like.
Among these, from the viewpoints of adhesion, dimensional stability, heat resistance, electrical insulation, and the like, it is preferable to contain an epoxy resin, a polyimide resin, or a liquid crystal resin, and more preferably an epoxy resin. Specific examples include ABF GX-13 manufactured by Ajinomoto Fine Techno Co., Ltd.

The solder resist, which is a kind of insulating layer material used for wiring protection, is described in detail in, for example, Japanese Patent Application Laid-Open No. 10-204150 and Japanese Patent Application Laid-Open No. 2003-222993. These materials can also be applied to the present invention if desired. As the solder resist, commercially available products may be used. Specific examples include PFR800 manufactured by Taiyo Ink Manufacturing Co., Ltd., PSR4000 (trade name), SR7200G manufactured by Hitachi Chemical Co., Ltd., and the like.

The resin base material (resin base material with a conductive film) having the conductive film obtained above can be used for various applications. Examples include printed wiring boards, TFTs (thin film transistors, Thin Film Transistors), FPCs (Flexible Printed Circuits, Flexible Printed Circuits), RFIDs (radio frequency identifiers), and the like.

The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these.
<Example 1>
(Synthesis of cupric oxide nanoparticles 1)
A predetermined amount of copper nitrate (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in purified water to prepare a 0.1 mol / l aqueous copper nitrate solution in advance. 100 ml of ion exchange water was placed in a glass 200 ml flask and heated to 90 ° C. in an oil bath. 20 ml each of the copper nitrate aqueous solution and 0.2 mol / l sodium hydroxide aqueous solution were added thereto within 10 seconds and heated for 10 minutes to obtain cupric oxide fine particles. Thereafter, the particles are collected by centrifugation (10000 G, 30 minutes), redispersed in ion-exchanged water, and then subjected to concentration by ultrafiltration using ion-exchanged water to sufficiently remove impurities. And a copper oxide paste having a particle concentration of 40% by mass was obtained. By XRD (abbreviation of X-ray diffraction, the same applies hereinafter) analysis, strong diffraction peaks derived from the (002) and (111) planes were observed near 35.5 ° and 38 °, respectively. Was confirmed to be cupric oxide. Moreover, as a result of TEM (abbreviation of Transmission Electron Microscope; hereinafter the same) observation, the average primary particle diameter of the cupric oxide nanoparticles 1 obtained as described above was 18 nm.

(Preparation of conductive film forming composition 1)
Cupric oxide paste (30 parts by mass, including 12 parts by mass as cupric oxide solids and 18 parts by mass of ion-exchanged water) obtained as described above, and (B) diethylene glycol (7.8 parts by mass). Part), ion-exchanged water (27.2 parts by mass), (D) 1-butanol (3 parts by mass), and ethanol (32 parts by mass), and a revolving mixer (THINKY, manufactured by Aritori Neritaro ARE) -250) for 5 minutes, followed by ultrasonic dispersion treatment to obtain a conductive film-forming composition 1.
The conductive film-forming composition 1 was diluted with ion-exchanged water so that the (A) cupric oxide nanoparticles were 0.01% by mass, and an ultraviolet-visible spectrophotometer (UV-2450, manufactured by Shimadzu Corporation) The absorbance α1 at a wavelength of 400 nm and the absorbance α2 at a wavelength of 600 nm of the composition obtained in the above were measured, and the ratio of α1 / α2 was determined to be 4.3.

Further, the particle size distribution of cupric oxide nanoparticles was measured using a diluted solution with a trade name Nanotrac particle size distribution analyzer UPA-EX150 (manufactured by Nikkiso Co., Ltd.).
As a result, the ratio of particles having a particle size of 200 nm or more in the cumulative volume particle size distribution measured by the dynamic light scattering method of the cupric oxide nanoparticles in the composition for forming a conductive film is based on the whole cupric oxide nanoparticles. 2%. The ratio of particles having a particle diameter of more than 0 nm and less than 100 nm and the ratio of particles having a particle diameter of 100 nm to less than 200 nm were also measured in the same manner. The results are shown in Table 1.

(Preparation of conductive film)
On a polyethylene naphthalate (PEN) base material (Q65HA, thickness 125 μm, manufactured by Teijin DuPont), a conductive film forming composition 1 is coated with a bar so as to have a wet film thickness of 12 μm, and dried at 50 ° C. for 1 minute. A coating film was obtained.
Thereafter, the obtained coating film was subjected to pulsed light irradiation treatment (Xenon's photosintering apparatus Sinteron 2000, irradiation energy: 5.5 J / cm ² , light irradiation twice at intervals of 3 seconds) to obtain a conductive film. . Table 1 shows the thickness of the obtained conductive film.

<Defect evaluation>
The obtained conductive film was observed at a magnification of 450 times using an optical microscope, and the presence or absence of defects and the state of defects were evaluated based on the following criteria. Practically, it is preferably A to B. The results are shown in Table 1.
"A": The conductive film is formed on the entire surface, and there are almost no defects.
“B”: There is a cracked and / or ablated portion in the conductive film.
"C": The entire surface of the conductive film is ablated and the conductive film cannot be formed.

<Conductivity>
About the obtained electrically conductive film, volume resistivity was measured using the four-probe method resistivity meter, and electroconductivity was evaluated. The evaluation criteria are as follows. In practice, it is required to be A, B or C. The results are shown in Table 1.
“A”: Volume resistivity is less than 100 μΩ · cm “B”: Volume resistivity is 100 μΩ · cm or more and less than 300 μΩ · cm • “C”: Volume resistivity is 300 μΩ · cm or more and less than 1000 μΩ · cm • “D” ”: Volume resistivity is 1000 μΩ · cm or more

<Comparative Example 1>
A conductive film-forming composition and a conductive film were prepared and evaluated in the same manner as in Example 1 except that 2,3-butanediol was used in place of diethylene glycol.

<Example 2>
Implemented except that 14.1 parts by mass of ethylene glycol is used in place of diethylene glycol, the total amount of the composition for forming a conductive film is 100 parts by mass, and the irradiation energy is changed to 5 J / cm ^2. In the same manner as in Example 1, a composition for forming a conductive film and a conductive film were prepared and evaluated.

<Example 3>
The amount of ethylene glycol was changed to 9.4 parts by mass, and 6 parts by mass of liquid A prepared by dissolving palladium acetate (0.12 parts by mass) in acetone (5.88 parts by mass) as a catalyst was added to form a conductive film. Conductive film forming composition in the same manner as in Example 2, except that the amount of ion-exchanged water was adjusted so that the total amount of the composition for use was 100 parts by mass, and the irradiation energy was changed to 4.5 J / cm ² . A conductive film was prepared and evaluated.
In Examples of the present specification, when palladium acetate was used as the metal catalyst (E), a mixture similar to the above liquid A was used.

<Examples 4 to 7, Comparative Example 2>
(B) For the formation of a conductive film in the same manner as in Example 3, except that the polyol-based organic solvent was used so that the components listed in the following Table 1 were used in the proportions shown in the same table, and the irradiation energy was changed to the values in the following Table 1. A composition and a conductive film were prepared and evaluated. In addition, the value of the irradiation energy of Example 5 is the same as that of Example 3.

<Comparative Example 3>
A conductive film-forming composition and a conductive film were obtained in the same manner as in Example 1 except that cupric oxide nanoparticles 2 (cupric oxide nanoparticles, manufactured by CI Kasei Co., Ltd.) having an average primary particle diameter of 48 nm were used. Was made.

<Comparative example 4>
(Synthesis of cupric oxide nanoparticles 3)
A predetermined amount of copper nitrate (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in purified water to prepare a 0.1 mol / l aqueous copper nitrate solution in advance. 100 ml of ethylene glycol was placed in a glass 200 ml flask and heated to 90 ° C. in an oil bath. Here, 15 ml each of the copper nitrate aqueous solution and 0.2 mol / l sodium hydroxide aqueous solution were added within 10 seconds and heated for 10 minutes to obtain cupric oxide fine particles. Thereafter, the particles are recovered by centrifugation (10000 G, 30 minutes), then redispersed in ion-exchanged water, and then subjected to ultrafiltration using ion-exchanged water to remove impurities, and concentrated to cupric oxide. A copper oxide paste having a particle concentration of 30% by mass was obtained. By XRD analysis, strong diffraction peaks derived from the (002) and (111) planes were observed near 35.5 ° and 38 °, respectively, and it was confirmed that the obtained particles were cupric oxide. As a result of TEM observation, the average primary particle diameter of the obtained cupric oxide nanoparticles 3 was 4 nm.

(Composition for forming conductive film, preparation of conductive film)
The cupric oxide dispersion containing cupric oxide nanoparticles 3 (40 parts by mass) obtained as described above, (B) diethylene glycol (7.8 parts by mass), and 17.2 parts by mass of ion-exchanged water. (D) 1-butanol (3 parts by mass) and ethanol (32 parts by mass) were mixed and subjected to ultrasonic dispersion treatment to obtain a composition for forming a conductive film.
A conductive film was prepared and evaluated in the same manner as in Example 1 using the conductive film-forming composition obtained as described above.

<Example 8>
(Synthesis of cupric oxide nanoparticles 4)
In the synthesis of cupric oxide nanoparticles, cupric oxide nanoparticles 4 were obtained in the same manner as in Example 1 except that the amount of the copper nitrate aqueous solution and the sodium hydroxide aqueous solution added was quadrupled. The average primary particle diameter of cupric oxide nanoparticles 4 was 10 nm.
(Composition for forming conductive film, preparation of conductive film)
A conductive film-forming composition and a conductive film were prepared and evaluated in the same manner as in Example 4 except that the cupric oxide dispersion containing cupric oxide nanoparticles 4 obtained as described above was used.

<Example 9>
Example 8 except that ethylene glycol was used instead of diethylene glycol, the amount of ethylene glycol was set to the amount shown in Table 1, and the amount of ion-exchanged water was adjusted so that the total amount of the composition for forming a conductive film was 100 parts by mass. Similarly, a composition for forming a conductive film and a conductive film were prepared and evaluated.
<Examples 10 and 11>
For the (B) polyol-based organic solvent and (C) polyoxyalkylene-based compound, the components shown in Table 1 below are used in the amounts shown in the same table, the thickness of the Wet film is 40 μm, the irradiation energy and the number of irradiations are shown in Table 1. Except having replaced with the value shown, the composition for electrically conductive film formation and the electrically conductive film were produced similarly to Example 8, and evaluated. In Example 11, (E) a metal catalyst was not used.
<Examples 12 to 15>
Example 8 For the (B) polyol organic solvent and (C) polyoxyalkylene compound, the components shown in Table 1 below were used in the amounts shown in the same table, and the irradiation energy was changed to the values shown in Table 1. The composition for electrically conductive film formation and the electrically conductive film were produced similarly, and evaluated. In Example 12, the metal catalyst (E) was not used. The irradiation energy of Example 12 was the same as that of Example 8. The amount of diethylene glycol in Example 15 was the same as in Example 8.

<Example 16>
A conductive film-forming composition and a conductive film were prepared and evaluated in the same manner as in Example 4 except that cupric oxide nanoparticles 5 having an average primary particle diameter of 28 nm prepared by a vapor phase method were used.
<Example 17>
A conductive film-forming composition and a conductive film were prepared and evaluated in the same manner as in Example 12 except that ion-exchanged water was added instead of 1-butanol and ethanol.

“Wt%” in Table 1 intends “mass%”.
In Table 1, “polyethylene glycol Mw 20000” intends polyethylene glycol having a weight average molecular weight of 20,000 (manufactured by Wako Pure Chemical Industries, Ltd.).
In Table 1, in each example and comparative example, (A) cupric oxide nanoparticles (net amount), (B) polyol organic solvent, (C) polyoxyalkylene compound, (E) metal The amount of the catalyst was shown as a concentration in the entire composition for forming a conductive film.

As shown in Table 1 above, when the conductive film forming composition of the present invention was used, it was confirmed that the formed conductive film had few defects and excellent conductivity.
Further, as can be seen from the comparison of Examples 8, 4, and 16, when α1 / α2 is within a predetermined range, the conductivity of the conductive film is increased as the average primary particle diameter is smaller and α1 / α2 is larger. It was confirmed that it was superior and the occurrence of defects could be further suppressed.

On the other hand, as shown in Comparative Example 1, it was confirmed that when the boiling point of the polyol-based organic solvent was smaller than the predetermined range, the conductivity and the generation of defects were inferior.
Moreover, as shown in Comparative Example 2, when the boiling point of the polyol organic solvent was larger than the predetermined range, it was confirmed that the conductivity was inferior. Moreover, when the boiling point of the polyol organic solvent was larger than the predetermined range, α1 / α2 was smaller than the predetermined range. From this, it is presumed that the dispersibility of cupric oxide nanoparticles is lowered when the boiling point of the polyol-based organic solvent is too high.
Further, as shown in Comparative Examples 3 and 4, when α1 / α2 was outside the predetermined range, it was confirmed that the conductivity and the generation of defects were inferior.

Claims

Cupric oxide nanoparticles,
A composition for forming a conductive film, comprising at least a polyol organic solvent having a boiling point of 190 to 340 ° C.,
The composition for electrically conductive film formation in which the ratio of the light absorbency in wavelength 400nm and wavelength 600nm measured with the spectrophotometer satisfy | fills the following formula | equation 1.
Formula 1 5> α1 / α2> 3
In Formula 1, α1 represents the absorbance of the composition at a wavelength of 400 nm, and α2 represents the absorbance of the composition at a wavelength of 600 nm.
The composition for forming a conductive film according to claim 1, wherein the cupric oxide nanoparticles have an average primary particle diameter of 2 to 25 nm.
Furthermore, the composition for electrically conductive film formation of Claim 1 or 2 containing the polyoxyalkylene type compound of weight average molecular weight 1,000 or more.
The composition for forming a conductive film according to claim 3, wherein the polyoxyalkylene compound is polyethylene glycol.
The ratio of particles having a particle diameter of 200 nm or more in the cumulative volume particle size distribution measured by a dynamic light scattering method of the cupric oxide nanoparticles is 15% or less of the whole cupric oxide nanoparticles. 5. The composition for forming a conductive film according to any one of 1 to 4.
Furthermore, it contains an alcohol-based organic solvent or a ketone-based organic solvent having a surface tension of 40 mN / m or less and a boiling point of 50 to 180 ° C.,
The composition for forming a conductive film according to any one of claims 1 to 5, wherein the content of the alcohol-based organic solvent or the ketone-based organic solvent is 1 to 50 mass% with respect to the total mass of the composition. .
The composition for forming a conductive film according to any one of claims 1 to 6, wherein a mass ratio of the cupric oxide nanoparticles to the polyol organic solvent is 1: 0.005 to 1: 2. .
The conductive film formation according to any one of claims 3 to 7, wherein a mass ratio of the cupric oxide nanoparticles to the polyoxyalkylene compound is 1: 0.01 to 1: 0.5. Composition.
The composition for forming a conductive film according to any one of claims 1 to 8, wherein the polyol organic solvent is a diol or a triol.
The conductive film-forming material according to any one of claims 1 to 9, wherein the polyol organic solvent is at least one selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, trimethylolpropane, and glycerin. Composition.
In addition, it contains a metal catalyst,
The conductive film-forming composition according to any one of claims 1 to 10, wherein a mass ratio of the cupric oxide nanoparticles to the metal catalyst is 1: 0.001 to 1: 0.1. .
The conductive film forming composition according to any one of claims 1 to 11, wherein the α1 / α2 is greater than 4 and less than 5.
The cupric oxide nanoparticles are produced by a wet method, and the average primary particle diameter of the cupric oxide nanoparticles is 2 to 25 nm. The composition for electrically conductive film formation of description.
Applying the composition for forming a conductive film according to any one of claims 1 to 13 on a resin substrate to form a coating film;
A process for producing a conductive film, comprising: subjecting the coating film to light irradiation treatment, and reducing the cupric oxide nanoparticles to form a conductive film containing metallic copper.