JP2012144755A - Method for production of metal copper film, and printing metal copper pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treatment method for reducing to a deep portion, a printable and formable copper-based particle deposition layer having good adhesiveness to a substrate, low volume resistivity without a substrate damage; and to provide a method for producing a metal copper film preventing copper precipitation outside a printing/coating part, and also a printing metal copper pattern.SOLUTION: The method for production of the metal copper film includes treating a copper-based particle deposition layer formed on the substrate and including particles comprising copper oxide with a gas mixture of gaseous formic acid and at least one organic solvent selected from gaseous monovalent alcohol, ester and ketone at 120°C or higher.

Description

  The present invention relates to a method for producing a metal copper film and a printed metal copper pattern produced thereby.

  Metallic copper has high electrical conductivity and thermal conductivity, and is widely used as a conductor wiring material, a heat transfer material, a heat exchange material, and a heat dissipation material.

  On the other hand, inkjet, jet dispenser, needle dispenser, dispenser, and plate printing can apply liquid material to any shape without using a photoresist process, so on-demand production, labor saving, material saving, low cost It is attracting attention from the point of conversion. In addition, with inkjet and jet dispensers that can be formed in a non-contact manner, printing on steps, curved surfaces, and small areas is possible, and patterns can be formed on a substrate having a shape that is impossible with plate printing.

As a printing ink for forming a metallic copper pattern by such printing, a dispersion of metallic copper nanoparticles (see Patent Document 1) and a solution or dispersion of a metal complex (see Patent Document 2) have been devised.
However, copper is stable in oxidation state at room temperature (25 ° C.), and always contains copper in the oxidation state. Therefore, copper is reduced in the oxidation state in order to exhibit conductor and heat conductivity as metal copper. It is necessary to make it a continuum.

  In copper ink using metallic copper nanoparticles, if a dispersant is included before use, after removing the dispersant, the copper oxide is reduced and the metallic copper particles are sintered and fused together to form a continuous body. There is a need to. As a method for removing and / or sintering such a dispersant, (a) RF plasma (see Patent Document 3) or hot wire method is used to activate hydrogen, (b) xenon flash irradiation in a hydrogen atmosphere, (C) Heating with a trihydric or higher polyhydric alcohol (see Patent Document 4), (d) Heating in hydrogen gas, or the like is used.

  However, such a combination of printing ink and sintering method has problems of low adhesion, peeling of treated printing layer, high volume resistivity, and deep property, and printing ink is used as conductor wiring material, heat transfer material, heat exchange. It could not be applied to materials and heat dissipation materials.

The cause of low adhesion, peeling of the treated printing layer, and high volume resistivity is due to the porous sintered body joining the particles by heating and sintering the metal element-containing particles in the printing ink. . In the sintering of metal nanoparticles at a temperature much lower than the melting point of the metal, metal atoms move within the particle to reduce the surface area using the large surface energy of the powder particle and the externally applied energy as driving forces. Then, the bonding / fusion between the particles proceeds (see Non-Patent Document 1).
However, when the bonding / fusion between the particles proceeds to some extent and the specific surface area is reduced, the progress of the fusion is decelerated and stopped. As a result, a porous sintered body is obtained.

  This is because the metal atoms move within the powder particles and do not actively precipitate on the surface of the substrate, so that voids remain between the conductor layer and the substrate and adhesion cannot be obtained. Conventionally, a conductor ink is printed on a polyimide precursor on a base resin (see Patent Document 5) or a conductor ink is printed on a semi-cured epoxy resin (see Patent Document 6). ), A method has been reported in which fluidity is imparted to the underlying resin to follow the conductor layer to obtain adhesion, but there are restrictions on the underlying resin material and the manufacturing method.

  For the same reason, in the sintering of metal nanoparticles at a temperature much lower than the melting point of the metal, the fusion between the particles stops when the specific surface area decreases to some extent as the sintering progresses, and the porous sponge A conductive layer. Accordingly, there is a problem that the volume resistivity does not become 10 times or less that of bulk copper in the conductive treatment at 200 ° C. or lower.

  Further, it has been reported that the same method is effective in removing an oil film and removing a photoresist resin in a method using activated hydrogen (RF plasma and surface wave plasma: see Patent Document 7, hot wire method) Atomic hydrogen treatment: see Non-Patent Document 2. As described above, in the method using activated hydrogen, it is also a problem that the resin substrate is damaged by the activated hydrogen.

On the other hand, it has been reported that a formic acid reflow furnace is effective in removing copper and solder oxide films as a technique using formic acid gas (see Patent Document 8). In the method using formic acid gas, the processing temperature is 120 to 250 ° C., and a metal copper film can be formed without damaging the substrate. A method of sintering printing ink using this technique has been reported (see Patent Documents 9 and 10). In addition, a method of forming a sintered body having a low volume resistivity without metallized copper diffusing around the application part is also described (see Patent Document 10).
However, even in these methods using formic acid gas, the main component of the copper-based particle deposition layer is metallic copper nanoparticles, and since this is heated, the sintered body becomes porous, and there is a problem in adhesion to the substrate. There is.

Japanese Patent No. 4155821 JP 2004-162110 A JP 2004-119686 A JP 2007-87735 A JP 2008-200557 A JP 2010-97808 A International Publication No. 2005/0555305 Japanese Patent No. 3373499 JP 2009-252685 A JP 2010-59535 A

Hwang, K.K. S. and R.R. S. German; “Sintering and Heterogeneous Catalysis,” 35, Plenum Press (1983). A. Izumi, H.I. Matsumura, Jpn. J. et al. Appl. Phys. 41, (2002) 4639-4641

  At present, a metal copper pattern that can be formed by printing, has good substrate adhesion, low volume resistivity, and deep metal property and has no substrate damage is desired. An object of the present invention is to provide a method for producing a metal copper film that has excellent substrate adhesion, low volume resistivity, little substrate damage, and can be reduced to a deep portion of copper. Furthermore, it is providing the printed metal copper pattern formed using the preparation method of a metal copper film | membrane.

As a method for producing a metallic copper film for solving the above-mentioned problems, a copper-based particle dispersion and a copper-based particle deposition layer on which the copper-based particle dispersion is printed include particles made of copper oxide. By allowing the gas having a functional group that easily coordinates to the copper formate molecule to coexist with the formic acid gas, the copper metal precipitates at a temperature of 120 ° C. or higher, The inventors have found that the deposition of metallic copper outside the copper-based particle deposition layer can be significantly suppressed, and have reached the present invention.
That is, the present invention is as follows.
(1) A copper-based particle deposition layer including particles made of copper oxide formed on a substrate is selected from gaseous formic acid and gaseous monovalent alcohol / ester / ketone at 120 ° C. or higher. A method for producing a metallic copper film, which comprises treating with a mixed gas with at least one organic solvent.
(2) The method for producing a metallic copper film according to (1), wherein the copper oxide is cuprous oxide and / or cupric oxide.
(3) The method for producing a metallic copper film according to (1) or (2), wherein the primary particle diameter of the particles made of copper oxide is 1 to 10,000 nm.
(4) The method for producing a metallic copper film according to any one of (1) to (3), wherein the copper-based particle deposition layer is formed on a substrate by a printing method.
(5) Printing method is ink jet printing, jet dispenser, dispenser, needle dispenser, screen printing, letterpress printing, intaglio printing, gravure printing, transfer printing, soft lithography, dip pen lithography, particle deposition method, comma coater, slit coater, die coater (4) The method for producing a metal copper film according to (4), which is at least one method selected from a gravure coater, a spray coater, a spin coater, a dip coater, and electrodeposition coating.
(6) The metal copper film according to any one of (1) to (5), wherein the substrate is at least one selected from metal, plastic, glass, ceramics, and composite materials thereof. Method.
(7) A printed metal copper pattern produced by the method for producing a metal copper film according to any one of (4) to (6).

  In the printed metal copper pattern produced by the method for producing a metal copper film of the present invention, as shown in FIG. 1B, a dense metal copper film is deposited in the vicinity of the substrate surface, and adhesion to the substrate is observed. Excellent. In the method for producing a metallic copper film of the present invention, it passes through the sublimable cuprous formate, so that the copper atoms can diffuse out of the particles by sublimation and the metallic copper is precipitated. From this, it is possible to obtain adhesion between the substrate and the metal copper film without using a resin substrate having followability on the substrate side. On the other hand, since a molecule having a functional group that easily coordinates to the copper formate molecule is allowed to coexist, it is possible to significantly suppress the precipitation of metallic copper outside the copper-based particle deposition layer.

(A) is a conceptual diagram of the copper-type particle deposition layer on a board | substrate, (b) is a conceptual diagram which shows that a metal copper film | membrane produces | generates from a board | substrate in the gas processing of this invention. In Example 1, it is a cross-sectional observation image by the scanning ion microscope of the metal copper film | membrane produced | generated by processing a copper-type particle deposition layer for 100 minutes with mixed gas. In Example 1, it is a cross-sectional observation image by the scanning ion microscope of the metal copper film | membrane produced | generated by processing a copper-type particle deposition layer for 5 minutes with mixed gas. In Example 1, it is a cross-sectional observation image by the scanning ion microscope of the metal copper film | membrane produced | generated by processing a copper-type particle deposition layer for 15 minutes with mixed gas.

Hereinafter, modes for carrying out the present invention will be described.
In the method for producing a metal copper film of the present invention, a copper-based particle deposition layer containing particles made of copper oxide formed on a substrate is formed by using gaseous formic acid and gaseous monovalent alcohol at 120 ° C. or higher. It is characterized by treating with a mixed gas with at least one organic solvent selected from / ester / ketone.
Hereinafter, a printed metal copper pattern produced by the method for producing a metal copper film and the method for producing a metal copper film of the present invention will be described.

The printed metal copper pattern of the present invention usually has a dense copper film having a thickness of 1 μm or more, which cannot be obtained by conventional reduction and sintering of copper-based nanoparticles, and as a result, has low resistance and high adhesion. First, the manufacturing method and principle will be described.
As shown to Fig.1 (a), the structure which has a copper-type particle deposition layer on a board | substrate is made to contact with the gas containing formic acid in the state heated at 120 degreeC or more. Copper oxide in the copper-based particle deposition layer reacts with formic acid to produce copper formate. The resulting copper formate sublimes and diffuses as a gas or thermally decomposes into metallic copper, water, and carbon dioxide. In this method, the sublimated copper formate can move over a relatively long distance, and the space between the particles can be filled with copper derived from copper oxide. The copper film thus formed becomes a dense copper film having a thickness of 1 μm or more as shown in FIG. 1B, and exhibits properties close to that of bulk metallic copper.

In contrast, in the conventional reduction and sintering of copper-based nanoparticles at 200 ° C. or lower, only the copper atoms on the surface of the particles that are in a higher energy state due to the surface energy are fused and necked, leaving the gaps between the particles as they are. As a result, there is a limit to the low resistance.
Hereinafter, each component of the present invention will be described.

First, the copper-based particle deposition layer will be described in detail.
(Copper particle deposition layer)
The copper-based particle deposition layer is a layer in which particles containing particles made of copper oxide are deposited, and the copper oxide is preferably cuprous oxide and / or cupric oxide. The ratio of copper oxide contained in the copper-based particle deposition layer is preferably 10% by mass or more, more preferably 50% by mass or more, still more preferably 60% by mass or more, in terms of mass ratio. It is particularly preferably at least 80% by mass, very particularly preferably at least 80% by mass, and most preferably at least 90% by mass. If the copper oxide ratio is less than 10% by mass, a dense copper film cannot be formed, which is not preferable.

The particles other than the particles made of copper oxide may contain a metal component having catalytic activity for the decomposition of copper oxide or copper formate, such as copper, platinum, palladium, rhodium, gold, silver, nickel, and the like.
In addition, from the copper-based particle deposition layer, for various purposes such as improving the denseness of the metal copper film produced by gas treatment containing formic acid, adjusting internal stress, and suppressing the precipitation of metallic copper outside the copper-based particle deposition layer. Accordingly, the copper-based particle deposition layer may contain an organic or inorganic additive such as a metal salt. Examples of the additive include 2,2′-bipyridyl, orthophenanthrin, potassium ferrocyanide, benzothiazole, thiazole, nicotinic acid, benzotriazole, potassium polysulfide, 8-azaguanine, 8-azaxanthine, and 8-aza. Hypoxanthine, adenine, 8-azaadenine, guanine, hypoxanthine, norbornadiene, polyethylene glycol, polypropylene glycol, polyethylene glycol monomethyl ether, polyethylene glycol dimethyl ether, sodium cyanide, cupron, potassium sulfide, sodium sulfide, sodium metasilicate, sodium germanate , Germanium dioxide, sodium stannate, sodium molybdate, sodium metavanadate, vanadium pentoxide, sodium sulfate , Potassium sulfate, nickel sulfate, copper sulfate, copper nitrate, copper chloride, copper formate, copper acetate, boric acid, potassium oxalate, thiourea, allylthiourea, thiomalic acid, thioglycolic acid, thiocyanic acid, glycolic acid, sodium carbonate, Examples include, but are not limited to, potassium nitrate and lead salts.

  Moreover, it is preferable that the particle | grains which consist of copper oxide have a primary particle diameter of 1-10000 nm, It is more preferable that it is 2-5000 nm, It is further more preferable that it is 3-3000 nm. If the primary particle diameter of the particles made of copper oxide is larger than 10,000 nm, it is not preferable because a dense copper film cannot be formed. The primary particle diameter of the particles is generally the number average particle diameter of the primary particles. The number average particle diameter can be determined by, for example, a laser diffraction scattering method.

  The thickness of the copper-based particle deposition layer formed on the substrate is determined based on the volume shrinkage when the copper oxide contained in the copper-based particle deposition layer is reduced and a metal copper film is formed. It is necessary to form it thicker. Therefore, the thickness of the copper-based particle deposition layer is preferably 0.01 μm or more. If the thickness of the copper-based particle deposition layer is less than 0.01 μm, there is a possibility that defects may occur in the resulting metal copper film, which is not preferable. Moreover, since there exists a possibility that reduction | restoration of copper oxide may become inadequate when it is too thick, 100 micrometers or less are preferable, 80 micrometers or less are more preferable, and 50 micrometers or less are especially preferable.

Next, a method for forming a copper-based particle deposition layer will be described in detail.
(Method for forming a copper-based particle deposition layer)
The copper-based particle deposition layer can be formed by preparing a dispersion containing copper-based particles, applying the dispersion as a coating liquid on a substrate, and drying. The dispersion containing copper-based particles refers to a dispersion containing copper oxide particles.

  The concentration of the copper-based particles in the dispersion is mainly limited by the viscosity and dispersibility that can be used in coating or printing techniques, and is preferably 5 to 80% by mass as the solid content, and 10 to 60% by mass. More preferably, it is more preferably 10 to 50% by mass.

  Dispersion includes ultrasonic dispersers, media dispersers such as bead mills, cavitation stirrers such as homomixers and silverson stirrers, opposed collision methods such as optimizers, ultra-thin high-speed rotating dispersers such as Claire SS5, and rotation and revolution types It can be performed using a mixer or the like.

  As the dispersion medium of the dispersion liquid, any copper-based particles can be dispersed. For example, N-methylpyrrolidone, dimethyl sulfoxide, propylene carbonate, γ-butyrolactone, sulfolane, propylene carbonate, cyclohexanone, anisole, N, N— Dimethylformamide, ethylene glycol monomethyl ether acetate, ethylene glycol monophenyl ether, diethylene glycol dimethyl ether, diethylene glycol monobutyl ether, dipropylene glycol monomethyl ether, ethylene glycol monomethyl ether, triethylene glycol monomethyl ether, triethylene glycol dimethyl ether, tripropylene glycol dimethyl ether, propylene Glycol monomethyl ether acetate, 1, - butylene glycol diacetate, and the like, but not limited thereto. These dispersion media can be used alone or in combination of two or more. Further, an adjusting agent for adjusting the surface tension of the dispersion may be included.

  The copper-based particle deposition layer can be formed by preparing a dispersion containing copper-based particles prepared by the above method, applying the dispersion as a coating liquid on a substrate, and drying.

The printing method used for the patterning of the copper-based particle deposition layer may be any method that allows the copper-based particle deposition layer to be attached to an arbitrary place on the substrate. Examples of such a method include inkjet printing and electrostatic attraction method. Inkjet printing (commonly called super ink jet), jet dispenser, dispenser, needle dispenser, screen printing, relief printing, intaglio printing, gravure printing, transfer printing, soft lithography, dip pen lithography, particle deposition method, comma coater, slit coater, die coater A gravure coater, a spray coater, a spin coater, a dip coater, or an electrodeposition coating can be used, but is not limited thereto.
Moreover, the metallic copper film produced by the printing method can be used as a printed metallic copper pattern. Furthermore, the metal copper film produced by the method for producing a metal copper film of the present invention is suitable as, for example, a conductor wiring, a bump, and a heat conduction path, and further requires heat dissipation. Etc. can be used.

  The substrate used as a base for forming the copper-based particle deposition layer by applying the dispersion liquid may be any substrate that can form the copper-based particle deposition layer. Examples of such a substrate include iron, copper, and gold. , Metals such as silver, nickel, cobalt, chromium and alloys containing these metals, polyimide, polyethylene naphthalate, polyethersulfone, polyethylene terephthalate, polyamideimide, polyetheretherketone, polycarbonate, liquid crystal polymer, epoxy resin, phenol Resins, cyanate ester resins, fiber reinforced resins, particle-filled resins, polyolefins, polyamides, polyphenylene sulfides, crosslinked polyvinyl resins and other plastics, glass, ceramics, and other composite materials.

Next, a method for producing a metal copper film produced from a copper-based particle deposition layer by gas treatment containing formic acid will be described in detail.
(Gas treatment)
The method for producing a metallic copper film of the present invention is characterized by treating with a mixed gas of gaseous formic acid and at least one organic solvent selected from gaseous monovalent alcohol / ester / ketone. . The organic solvent has a polarity for coordination with copper formate, and the vapor pressure of the organic solvent is preferably equal to or higher than formic acid. For example, for monohydric alcohols, methanol, ethanol, 1-propanol, 2-propanol, for esters, methyl formate, ethyl formate, propyl formate, isopropyl formate, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, ketone, Examples include, but are not limited to, acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl isopropyl ketone, methyl butyl ketone, methyl isobutyl ketone and the like. Moreover, it is preferable that the ratio of the gas of the organic solvent in mixed gas is 1-90 volume%, It is more preferable that it is 2-80 volume%, It is further more preferable that it is 3-70 volume%.

The method for producing the mixed gas is as follows: (1) Mixing liquid formic acid and a liquid organic solvent to form a mixed liquid, and heating or depressurizing it to form a gas, and then subject to treatment (copper-based particle deposition layer; ). Alternatively, a gas that does not react with formic acid and an organic solvent is used as a carrier, and the mixed liquid is bubbled to introduce the mixed gas together with the carrier gas to an object to be processed. (2) Liquid formic acid and liquid organic solvent are separately heated or reduced in pressure to form a gas, mixed in a gas flow path to form a mixed gas, and led to the object to be processed. Alternatively, for example, a gas that does not react with formic acid and an organic solvent is used as a carrier, and each liquid is bubbled and mixed with a carrier gas in a flow path to form a mixed gas, which is then led to an object to be processed. It is not limited to.
In the case of the method (1), the mixing ratio of the liquid formic acid and the liquid organic solvent is preferably a formic acid: organic solvent = 1-9: 9-1, preferably 5-9: 5-1. Is more preferable.

  The carrier gas is a gas that does not react with formic acid and an organic solvent, and is contained in the copper-based particle dispersion and / or the copper-based particle deposition layer, copper oxide, dispersion medium, surface conditioner, additive, and metallic copper to be generated It is preferable that the gas does not react with. For example, rare gases such as helium, neon, and argon, nitrogen, carbon dioxide, and the like can be given.

  When liquid formic acid adheres to the object to be treated, the temperature of the object to be treated decreases to 100 ° C., which is the boiling point of formic acid, the reduction does not proceed, and a part of the copper oxide is dissolved in formic acid. It is preferable to prevent liquid formic acid from adhering to the object to be treated because problems such as precipitation of copper outside the application site occur.

(Pretreatment of gas treatment)
As a pretreatment for the gas treatment, it is desirable to remove the dispersion medium remaining in the printed copper-based particle deposition layer. Examples of the removal method include heat removal, reduced pressure removal, and the like. A method of removing the object heated to 120 ° C. or higher through the carrier gas is preferable.

(Processing conditions)
The treatment temperature with the mixed gas is 120 ° C. or higher, which is the temperature at which metallic copper is deposited, and 140 ° C. or higher is preferable from the viewpoint of reaction rate. The upper limit of the processing temperature is defined by the heat resistant temperature of the substrate, but is preferably 250 ° C. or lower. Further, the treatment pressure is not particularly limited and may be any of atmospheric pressure, reduced pressure, and increased pressure. Moreover, the processing time by mixed gas is 5 to 180 minutes normally, and 10 to 120 minutes are preferable.

(After gas treatment)
If the gas used in the treatment remains on the surface of the copper metal, it is highly likely that the copper metal will be corroded. Therefore, a formic acid removal step may be provided after the gas treatment. As a method for removing the mixed gas containing formic acid gas, heating under an oxygen-free gas stream such as nitrogen, heating under reduced pressure, or washing with water can be used. As heating in an oxygen-free gas stream, heating by supplying an oxygen-free gas that does not contain formic acid gas in a formic acid gas treatment tank, heating in an oxygen-free gas oven, or a heat source in an oxygen-free gas stream may be used. it can. As heating under reduced pressure, when gas treatment is performed in a reduced-pressure tank, reduced-pressure heating with a formic acid gas being stopped and a reduced-pressure oven can be used.

EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to this.

Example 1
(Preparation of copper particle dispersion)
The copper-based particle dispersion was prepared by weighing 40 g of copper oxide nanoparticles (number average primary particle size 70 nm, manufactured by C.I. Kasei Co., Ltd.) in a plastic bottle and γ-butyrolactone (Wako Pure Chemical Industries, Ltd.) so that the solid content was 40% by mass. After being sealed, the mixture was shaken and mixed, and then treated with an ultrasonic homogenizer (US-600TCVP, manufactured by Nippon Seiki Seisakusho Co., Ltd.) at 19.5 kHz and 600 W for 5 minutes.

(Preparation of copper particle deposition layer sample)
The copper-based particle dispersion was dropped onto a glass slide having a thickness of 1 mm, and applied with a baker applicator (YBA type, manufactured by Yoshimitsu Seiki Co., Ltd.) adjusted to a gap of 50 μm. Thereafter, it was placed on a hot plate heated to 60 ° C. and dried for 30 minutes to obtain a copper-based particle deposition layer sample having a thickness of 15 μm.

(Mixed gas treatment)
Formic acid (manufactured by Wako Pure Chemical Industries, Ltd.) and methanol (manufactured by Wako Pure Chemical Industries, Ltd.) were introduced into the air-washing bottle at a mass ratio of 7: 3, and nitrogen was bubbled into a mixed gas generator. The copper-based particle deposition layer sample was set on a copper plate placed on the bottom of a flat bottom separable flask heated in an oil bath. A chromel alumel thermocouple was set on this surface, and the sample temperature was measured. The sample gas is heated in an oil bath at 240 ° C while flowing nitrogen into the separable flask in which the sample is set. After the sample temperature becomes constant (180 ° C), the formic acid / methanol mixed gas generated by the mixed gas generator is removed. Nitrogen gas contained was passed through the separable flask and treated with gas for 100 minutes. At that time, it was recognized that the entire copper-based particle deposition layer that was black changed to a copper color 60 minutes after the introduction of the mixed gas. After the treatment, the mixed gas generator was removed, and the separable flask was allowed to cool while flowing nitrogen. After the sample became 60 ° C. or lower, the sample was taken out into the air. Table 1 shows the appearance and the presence or absence of metal copper deposition outside the copper-based particle deposition layer.
The appearance was visually observed, and the presence or absence of metal copper deposition outside the copper-based particle deposition layer was confirmed using an optical microscope. The amount of metal copper deposited (diffused amount) outside the copper-based particle deposition layer (around the coating portion) was less than 5 μm, a small amount was 5-50 μm, and a large amount was more than 50 μm. The same applies hereinafter.

(Example 2)
The mixed gas treatment was performed under the same conditions as in Example 1 except that methanol in the mixed gas treatment was replaced with ethanol (Wako Pure Chemical Industries, Ltd.). Table 1 shows the appearance and the presence or absence of metal copper deposition outside the copper-based particle deposition layer.

(Example 3)
The mixed gas treatment was performed under the same conditions as in Example 1 except that methanol in the mixed gas treatment was replaced with 2-propanol (manufactured by Wako Pure Chemical Industries, Ltd.). Table 1 shows the appearance and the presence or absence of metal copper deposition outside the copper-based particle deposition layer.

Example 4
The mixed gas treatment was performed under the same conditions as in Example 1 except that methanol in the mixed gas treatment was replaced with methyl formate (manufactured by Wako Pure Chemical Industries, Ltd.). Table 1 shows the appearance and the presence or absence of metal copper deposition outside the copper-based particle deposition layer.

(Example 5)
The mixed gas treatment was performed under the same conditions as in Example 1 except that methanol in the mixed gas treatment was replaced with ethyl formate (manufactured by Wako Pure Chemical Industries, Ltd.). Table 1 shows the appearance and the presence or absence of metal copper deposition outside the copper-based particle deposition layer.

(Example 6)
The mixed gas treatment was performed under the same conditions as in Example 1 except that methanol in the mixed gas treatment was replaced with acetone (Wako Pure Chemical Industries, Ltd.). Table 1 shows the appearance and the presence or absence of metal copper deposition outside the copper-based particle deposition layer.

(Example 7)
Mixed gas treatment under the same conditions as in Example 1 except that the slide glass in the preparation of the copper-based particle deposition layer sample was replaced with a polyimide resin (Upilex S50, trade name of Ube Industries, Ltd., film thickness 50 μm). Went. Table 1 shows the appearance and the presence or absence of metal copper deposition outside the copper-based particle deposition layer.

(Comparative Example 1)
In the mixed gas treatment, the mixed gas treatment was performed under the same conditions as in Example 1 except that the mixed gas was formic acid gas not containing methanol. Table 1 shows the appearance and the presence or absence of metal copper deposition outside the copper-based particle deposition layer.

(Comparative Example 2)
In the mixed gas treatment, the mixed gas treatment was performed under the same conditions as in Example 1 except that methanol was replaced with water. Table 1 shows the appearance and the presence or absence of metal copper deposition outside the copper-based particle deposition layer.

(Comparative Example 3)
The mixed gas treatment was performed under the same conditions as in Example 1 except that methanol was replaced with ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.). Table 1 shows the appearance and the presence or absence of metal copper deposition outside the copper-based particle deposition layer.

  In Examples 1 to 7, there was no or a small amount of metallic copper deposited outside the copper-based particle deposition layer. On the other hand, in Comparative Examples 1 to 3 in which no specific organic solvent was used, a large amount of metallic copper was deposited outside the copper-based particle deposition layer.

  The cross-sectional SIM (scanning ion microscope) observation image of the metal copper film produced in Example 1 is shown in FIG. Moreover, in Example 1, the cross-section SIM observation image of the metal copper film produced by shortening the gas treatment time to 5 minutes or 15 minutes is shown in FIG. 3 (5 minutes) and FIG. 4 (15 minutes), respectively. From FIG. 2, it can be seen that approximately 1 μm of metal copper crystals were formed. 3 and 4 show that metallic copper nuclei are generated on the slide glass, and that the metallic copper has grown with increasing time.

(Reference Example 1)
(Verification experiment using copper (II) formate as the deposition layer)
Methanol (manufactured by Wako Pure Chemical Industries, Ltd.) was placed in the washing bottle, and nitrogen was bubbled into a methanol gas generator. Place the powder of copper (II) formate tetrahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) on a slide glass and use it as a deposition layer sample. Set on top. A chromel alumel thermocouple was set on this surface, and the sample temperature was measured. After flowing the nitrogen into the separable flask in which this sample was set and heating it in an oil bath at 180 ° C and the temperature of the sample became constant (145 ° C), nitrogen gas containing methanol gas generated by the gas generator was removed. This separable flask was gassed for 10 minutes. At that time, it was recognized that the copper (II) formate tetrahydrate, which was dark green, changed to a copper color 60 minutes after the introduction of methanol gas. After the treatment, the methanol gas generator was removed, and the separable flask was allowed to cool while flowing nitrogen. After the sample became 60 ° C. or lower, the sample was taken out into the air. Table 2 shows the appearance and the presence or absence of metallic copper deposition outside the deposited layer.

(Reference Example 2)
Gas treatment was performed under the same conditions as in Reference Example 1 except that the methanol in Reference Example 1 was replaced with ethanol (Wako Pure Chemical Industries, Ltd.). Table 2 shows the appearance and presence / absence of metal copper deposition outside the deposited layer.

(Reference Example 3)
Gas treatment was performed under the same conditions as in Reference Example 1 except that the methanol in Reference Example 1 was replaced with 2-propanol (Wako Pure Chemical Industries, Ltd.). Table 2 shows the appearance and presence / absence of metal copper deposition outside the deposited layer.

(Reference Example 4)
Gas treatment was carried out under the same conditions as in Reference Example 1 except that methanol of Reference Example 1 was replaced with methyl formate (manufactured by Wako Pure Chemical Industries, Ltd.). Table 2 shows the appearance and presence / absence of metal copper deposition outside the deposited layer.

(Reference Example 5)
Gas treatment was carried out under the same conditions as in Reference Example 1 except that methanol in Reference Example 1 was replaced with ethyl formate (manufactured by Wako Pure Chemical Industries, Ltd.). Table 2 shows the appearance and presence / absence of metal copper deposition outside the deposited layer.

(Reference Example 6)
Gas treatment was performed under the same conditions as in Reference Example 1 except that methanol in Reference Example 1 was replaced with acetone (Wako Pure Chemical Industries, Ltd.). Table 2 shows the appearance and presence / absence of metal copper deposition outside the deposited layer.

(Reference Example 7)
Gas treatment was performed under the same conditions as in Reference Example 1 except that only the methanol gas was passed without using the methanol of Reference Example 1. Table 2 shows the appearance and presence / absence of metal copper deposition outside the deposited layer.

(Reference Example 8)
Gas treatment was performed under the same conditions as in Reference Example 1 except that methanol in Reference Example 1 was replaced with water. Table 2 shows the appearance and presence / absence of metal copper deposition outside the deposited layer.

(Reference Example 9)
Gas treatment was performed under the same conditions as in Reference Example 1 except that the methanol in Reference Example 1 was replaced with ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.). Table 2 shows the appearance and presence / absence of metal copper deposition outside the deposited layer.

In Reference Examples 1 to 6, there was no precipitation of metallic copper outside the deposited layer. On the other hand, in Reference Examples 7 to 9 in which no specific organic solvent was used, a large amount of metal copper was deposited outside the deposited layer.
The organic solvent has a polarity for coordinating with copper formate and has a functional group that easily coordinates with the copper formate molecule. By coordinating the specific organic solvent gas with copper formate, the temperature is 120 ° C. or higher. It can be seen that the metal copper is precipitated, and the precipitation of the copper metal outside the copper-based particle deposition layer is greatly suppressed. Therefore, it turns out that the method of using copper oxide as a copper formate and using a specific organic solvent gas in combination with formic acid gas is effective.

  As described above, in the present invention, the copper-based particle deposition layer includes particles made of copper oxide, and the reduction method is at least selected from gaseous formic acid and gaseous monovalent alcohol / ester / ketone. By using a mixed gas with one kind of organic solvent, a dense metallic copper film having a thickness of 1 μm or more, which cannot be obtained by conventional reduction and sintering of copper-based nanoparticles, was obtained. Furthermore, the deposition of metallic copper outside the copper-based particle deposition layer can be greatly suppressed.

01: Substrate, 11: Copper-based particle deposition layer, 12: Metallic copper film

Claims (7)

  A copper-based particle deposition layer containing particles made of copper oxide formed on a substrate is at least one selected from gaseous formic acid and gaseous monovalent alcohol / ester / ketone at 120 ° C. or higher. A method for producing a metallic copper film, characterized by treating with a mixed gas with an organic solvent.   The method for producing a metal copper film according to claim 1, wherein the copper oxide is cuprous oxide and / or cupric oxide.   The method for producing a metallic copper film according to claim 1 or 2, wherein the primary particle diameter of the particles made of copper oxide is 1 to 10,000 nm.   4. The method for producing a metal copper film according to claim 1, wherein the copper-based particle deposition layer is formed on the substrate by a printing method.   Printing method is inkjet printing, jet dispenser, dispenser, needle dispenser, screen printing, letterpress printing, intaglio printing, gravure printing, transfer printing, soft lithography, dip pen lithography, particle deposition method, comma coater, slit coater, die coater, gravure coater The method for producing a metallic copper film according to claim 4, which is at least one method selected from spray coater, spin coater, dip coater, and electrodeposition coating.   6. The method for producing a metallic copper film according to claim 1, wherein the substrate is at least one selected from metal, plastic, glass, ceramics, and composite materials thereof.   A printed metal copper pattern produced by the method for producing a metal copper film according to claim 4.

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