JP2008016360A - Manufacturing method of conductive metal coating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a metal coating having a low specific resistance value by using a metal particulate-dispersed liquid having low viscosity and baking it at a low temperature of not more than 250°C. <P>SOLUTION: After applying the particulate-dispersed liquid obtained by dispersing a metal particulate or a metal oxide particulate having an average particle diameter in the range of 1-100 nm to a substrate, it is baked at a temperature of not more than 250°C under a reducing atmosphere. In addition, the average particle diameter of the metal particulate or the metal oxide particulate is preferably not more than 10 nm, and σ/D value (σ: standard deviation, D: average particle diameter) is preferably not more than 0.2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a conductive metal film, and more specifically, a dispersion of nano-sized metal fine particles or metal oxide fine particles is applied to a substrate and then baked to form a conductive metal film having a low specific resistance value. Regarding the method.

  It is well known that a conductive metal film is formed by applying a dispersion of metal fine particles or metal oxide fine particles to a substrate and then firing to form electrodes, wirings, and electronic circuits. It is in place.

For example, Patent Document 1 includes a paste containing metal fine particles such as gold, silver and copper having an average particle diameter of 1 to 100 nm coated with a compound capable of coordinating with metal fine particles such as amine, alcohol and thiol. It is described that a multilayer wiring board is manufactured using the same. However, the viscosity of the paste shown in the examples is as high as about 80 Pa · s, and the specific resistance value of the thermoset is as high as 1 × 10 ⁻⁵ Ω · cm or more.

  Patent Document 2 discloses that a metal paste coating is calcined in a vacuum, then calcined as an oxidizing atmosphere to oxidize and remove residual decomposition products, and further oxidized in a reducing atmosphere. It is described that a metal thin film is formed by reducing the metal and performing main firing. However, this method requires a special apparatus such as a vacuum incinerator, and there is a problem that the thin film obtained by this method has insufficient adhesion to the substrate.

  In Patent Document 3, a dispersion in which a reducible metal oxide having a particle size of 200 nm or less is applied to a substrate, and then fired in an inert atmosphere and then in a reducing atmosphere to form a metal film. It is described to form. However, it cannot be said that the specific resistance value of the metal coating obtained by firing at this low temperature is sufficiently low.

JP 2002-299833 A JP-A-10-294018 Japanese Patent Application Laid-Open No. 2004-164876

  The present invention provides a novel method for forming a metal film, which can easily form a metal film having a low specific resistance value by using a metal fine particle dispersion having a low viscosity and firing it at a low temperature of 250 ° C. or lower. The purpose is to do.

According to the studies by the present inventors, it has been found that the above problem can be solved by the following invention.
(1) A fine particle dispersion in which metal fine particles or metal oxide fine particles having an average particle diameter in the range of 1 to 100 nm are applied to a substrate and then fired at a temperature of 250 ° C. or lower in a reducing atmosphere. A method for producing a conductive metal coating.
(2) The method for producing a conductive metal film according to the above (1), wherein the fine particle dispersion contains at least one compound selected from an amine compound having 6 to 10 carbon atoms and a carboxylic acid compound.
(3) The content of at least one compound selected from an amine compound having 6 to 10 carbon atoms and a carboxylic acid compound in the fine particle dispersion is 30 to 150 parts by mass with respect to 100 parts by mass of the metal fine particles or metal oxide fine particles. A method for producing a conductive metal film according to (2) above.
(4) The average particle size of the metal fine particles or metal oxide fine particles is 10 nm or less, and the σ / D value (σ: standard deviation, D: average particle size) is 0.2 or less. A method for producing any one of the conductive metal coatings.
(5) Any of (1) to (4) above, wherein the metal is at least one selected from Pt, Pd, Ru, Ag, Fe, Co, Ni, Cu, Mo, In, Ir, Ti, and Al A method for producing a conductive metal film.
(6) The method for producing a conductive metal film according to any one of (1) to (5), wherein the fine particle dispersion has a viscosity of 10 Pa · s or less.

  According to the method of the present invention, a metal film having a low specific resistance can be easily formed without using a special apparatus. Further, since the fine particle dispersion used in the present invention has a low viscosity and is easy to handle, the method of the present invention is suitable for the production of a conductor for an electronic circuit.

  The “fine particle dispersion” used in the present invention is a dispersion of metal fine particles or metal oxide fine particles having an average particle diameter of 1 to 100 nm, preferably 1 to 50 nm, more preferably 2 to 10 nm, dispersed in an organic solvent. It is. The metal constituting the metal fine particles or metal oxide fine particles may be any metal as long as it is generally used for forming a conductive metal film. For example, Pt, Pd, Ru, Ag, Fe, Co, Ni, Cu, Mo, In, Ir, Ti, Al, etc. can be mentioned. These may be used alone or in combination of two or more. Among these, copper (Cu) is preferably used. Of the above metal fine particles or metal oxide fine particles, those having a uniform particle diameter, specifically, when the average particle diameter is D and the standard deviation is σ, the σ / D value is 0.01 to 0.00. Those having a range of 5, preferably 0.05 to 0.2 are preferably used.

  The particle diameter of the fine particles in the fine particle dispersion was measured using a field emission transmission electron microscope (FE-TEM), and based on this, the average particle diameter (D) and the standard deviation (σ) were determined.

  As the organic solvent, any organic solvent can be used as long as it is generally used for the preparation of this kind of fine metal particle dispersion. Among these, those that readily volatilize during firing at 250 ° C. or lower are preferably used. Specifically, for example, hydrocarbons such as normal hexane, cyclohexane, normal pentane, normal heptane, octane, decane, dodecane, tetradecane, hexadecane, toluene, xylene, methanol, ethanol, propanol, butanol, hexanol, heptanol, octanol , Decanol, cyclohexanol, 2-ethyl-1-hexanol, ethylene glycol, diethylene glycol, 1,2-propanediol, 1,4-butanediol, 2,3-butanediol, pentanediol, hexanediol, octanediol, 2 -Dimethylaminoethanol, 2-diethylaminoethanol, 2-dimethylaminoisopropanol, 3-diethylamino-1-propanol, 2-dimethylamino-2-propyl Propanol, 2-methyl-aminoethanol, 4-alcohols such as dimethyl-amino-1-butanol, methyl ethyl ketone, acetone, methyl isobutyl ketone, and the like ketones such as acetylacetone.

  The fine particle dispersion preferably contains an organic compound capable of coordinating with a metal, for example, an amine compound, a thiol compound, a carboxylic acid compound, etc., in order to prevent aggregation of the fine particles. Of these, amine compounds having 6 to 10 carbon atoms and carboxylic acid compounds are preferably used. Specific examples of these compounds include, for example, hexylamine, heptylamine, octylamine, nonylamine, decylamine, 2-ethylhexylamine, 1,1,3,3-tetramethylbutylamine, cyclohexylamine, N, N-diethylcyclohexylamine. , N-methylhexylamine, N-methylcyclohexylamine, cycloheptylamine, amine compounds such as 1-methylheptylamine, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, 2-ethylhexanoic acid, 2- Examples thereof include carboxylic acid compounds such as methylheptanoic acid, 4-methyloctanoic acid, gluconic acid, and salicylic acid. Of these, hexylamine, octylamine, 2-ethylhexylamine, decanoic acid and 2-ethylhexanoic acid are preferably used. These may be used alone or in combination of two or more.

  The content of the organic compound is 30 to 150 parts by mass, preferably 50 to 100 parts by mass, per 100 parts by mass of the metal fine particles or metal oxide fine particles in the dispersion. If the content of the organic compound is too small, aggregation of fine particles is likely to occur, and even if used in a large amount, the effect of preventing further aggregation of fine particles cannot be obtained, and problems such as an increase in viscosity occur.

  The fine particle dispersion can be prepared by a generally well-known method, and the preparation method is not particularly limited. For example, a copper fine particle dispersion will be described as an example. After mixing a copper compound and an amine compound, a reducing agent is added to the mixed solution, such as hydrogen, sodium borohydride, dimethylaminoborane, ascorbic acid, formaldehyde and the like. A copper fine particle dispersion can be obtained by performing a reduction treatment with the addition of.

  The viscosity of the fine particle dispersion is usually 10 mPa · s to 10 Pa · s, preferably 10 mPa · s to 100 mPa · s.

  In particular, a fine particle dispersion obtained by dispersing copper fine particles having an average particle size of 10 nm or less and a σ / D value of 0.2 or less together with an amine compound having 6 to 10 carbon atoms in an organic solvent is as described above. Since it has a low viscosity, is excellent in workability for application to a substrate, and forms a copper film having a low specific resistance value by firing, it is preferably used.

  According to this invention, after apply | coating the said fine particle dispersion to a board | substrate, it bakes at the temperature of 250 degrees C or less in a reducing atmosphere, Preferably it is the range of 150-250 degreeC. Examples of the reducing atmosphere include a mixed gas of hydrogen and nitrogen. In this case, it is sufficient that the hydrogen concentration is 0.5 to 10% by volume.

  There is no restriction | limiting in particular about the said board | substrate, For example, the board | substrate generally used for preparation of an electronic circuit can be mentioned. In the present invention, since baking is performed at a temperature of 250 ° C. or lower, a plastic substrate having low heat resistance can be used.

  Moreover, about the coating method of the said fine particle dispersion to a board | substrate, normal coating means, such as an inkjet printing system, a screen printing method, a dip coating method, a spray method, a spin coating method, an inkjet method, can be used. The fine particle dispersion of the present invention is particularly preferably used in the ink jet method.

  The invention is further illustrated by the following examples, which illustrate advantageous embodiments of the invention.

(Example 1)
15.7 g of copper acetate monohydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and 90.6 g of octylamine (manufactured by Wako Pure Chemical Industries, Ltd.) are added to a 1 L glass beaker and stirred at 40 ° C. for 10 minutes. Mix. Next, the glass beaker was placed in a constant temperature water bath at 20 ° C., and a reduced treatment was performed by gradually adding the dissolved dimethylamine borane solution.

  To the solution after the reduction treatment, 100 g of acetone and 10 g of water were added and allowed to stand for a while, and then a precipitate made of copper and organic matter was separated and collected by filtration. After the decane was added to the recovered product and dissolved, it was filtered to obtain a decane dispersion containing 40% by mass of copper fine particles and 20% by mass of octylamine. The viscosity of this dispersion was 30 mPa · s. Further, when this dispersion was observed by FE-SEM, it was confirmed that the average particle diameter of the copper fine particles was 5 nm and the σ / D value was 0.15.

  Next, it printed by the inkjet printing system on said glass plate using said decane dispersion liquid (copper fine particle dispersion liquid). After printing, the above glass plate was placed in a firing furnace, and while flowing a hydrogen-nitrogen mixed gas (5% by volume of hydrogen), the temperature was raised to 200 ° C. over 30 minutes, and the temperature was maintained for 30 minutes after being heated. Formed. The obtained copper thin film had an average film thickness of 2 μm and a specific resistance value of 4.0 μΩ · cm. Moreover, although the tape was stuck and peeled off on the copper thin film surface, peeling was hardly recognized.

(Example 2)
15.7 g of copper acetate monohydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and 130.2 g of dodecylamine (manufactured by Wako Pure Chemical Industries, Ltd.) are added to a 1 L glass beaker and stirred at 60 ° C. for 10 minutes. Mix. Next, the glass beaker was placed in a constant temperature water bath at 20 ° C., and a reduced treatment was carried out by gradually adding the dissolved dimethylamine borane solution.

  To the solution after the reduction treatment, 100 g of acetone and 10 g of water were added and allowed to stand for a while, and then a precipitate made of copper and organic matter was separated and collected by filtration. After the decane was added to the recovered product and dissolved, it was filtered to obtain a decane dispersion containing 40% by mass of copper fine particles and 20% by mass of dodecylamine. The viscosity of this dispersion was 60 mPa · s. Moreover, when this dispersion liquid was observed by FE-SEM, it was confirmed that the average particle diameter of copper fine particles was 7 nm, and (sigma) / D value was 0.15.

  Next, it printed by the inkjet printing system on said glass plate using said decane dispersion liquid (copper fine particle dispersion liquid). After printing, the above glass plate was placed in a firing furnace, and while flowing a hydrogen-nitrogen mixed gas (5% by volume of hydrogen), the temperature was raised to 200 ° C. over 30 minutes, and the temperature was maintained for 30 minutes after being heated. Formed. The obtained copper thin film had an average film thickness of 2 μm and a specific resistance value of 8.0 μΩ · cm.

(Example 3)
Into a 1 L glass beaker, 15.7 g of copper acetate monohydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and 100.5 g of 2-ethylhexylamine (manufactured by Wako Pure Chemical Industries, Ltd.) are added, and 10 at 30 ° C. Stir and mix for a minute. Next, the glass beaker was placed in a constant temperature water bath at 20 ° C., and a reduced treatment was carried out by gradually adding the dissolved dimethylamine borane solution.

  To the solution after the reduction treatment, 100 g of acetone and 10 g of water were added and allowed to stand for a while, and then a precipitate made of copper and organic matter was separated and collected by filtration. Tetradecane was added to the recovered material and redissolved, followed by filtration to obtain a decane dispersion containing 40% by mass of copper fine particles and 20% by mass of 2-ethylhexylamine. The viscosity of this dispersion was 40 mPa · s. Further, when this dispersion was observed by FE-SEM, it was confirmed that the average particle diameter of the copper fine particles was 5 nm and the σ / D value was 0.15.

  Next, it printed by the inkjet printing system on said glass plate using said decane dispersion liquid (copper fine particle dispersion liquid). After printing, the above glass plate was placed in a firing furnace, and while flowing a hydrogen-nitrogen mixed gas (5% by volume of hydrogen), the temperature was raised to 200 ° C. over 30 minutes, and the temperature was maintained for 30 minutes after being heated. Formed. The obtained copper thin film had an average film thickness of 2 μm and a specific resistance value of 6.0 μΩ · cm. Moreover, although the tape was stuck and peeled off on the copper thin film surface, peeling was hardly recognized.

Example 4
Add 15.7 g of copper acetate monohydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and 80.2 g of 1,1,3,3-tetramethylbutylamine (manufactured by Wako Pure Chemical Industries, Ltd.) to a 1 L glass beaker. And stirring and mixing at 30 ° C. for 10 minutes. Next, the glass beaker was placed in a constant temperature water bath at 20 ° C., and a reduced treatment was carried out by gradually adding the dissolved dimethylamine borane solution.

  To the solution after the reduction treatment, 100 g of acetone and 10 g of water were added and allowed to stand for a while, and then a precipitate made of copper and organic matter was separated and collected by filtration. Tetradecane was added to the recovered product and redissolved, followed by filtration to obtain a tetradecane dispersion containing 40% by mass of copper fine particles and 20% by mass of 1,1,3,3-tetramethylbutylamine. The viscosity of this dispersion was 40 mPa · s. Further, when this dispersion was observed by FE-SEM, it was confirmed that the average particle diameter of the copper fine particles was 5 nm and the σ / D value was 0.15.

Next, it printed by the inkjet printing system on said glass plate using said decane dispersion liquid (copper fine particle dispersion liquid). After printing, the above glass plate was placed in a firing furnace, and while flowing a hydrogen-nitrogen mixed gas (5% by volume of hydrogen), the temperature was raised to 200 ° C. over 30 minutes, and the temperature was maintained for 30 minutes after being heated. Formed. The obtained copper thin film had an average film thickness of 2 μm and a specific resistance value of 7.0 μΩ · cm.

Claims (6)

Conductivity is characterized in that a fine particle dispersion in which metal fine particles or metal oxide fine particles having an average particle diameter in the range of 1 to 100 nm are dispersed is applied to a substrate and then fired at a temperature of 250 ° C. or lower in a reducing atmosphere. For producing a conductive metal film. The method for producing a conductive metal film according to claim 1, wherein the fine particle dispersion contains at least one compound selected from an amine compound having 6 to 10 carbon atoms and a carboxylic acid compound. The content of at least one compound selected from an amine compound having 6 to 10 carbon atoms and a carboxylic acid compound in the fine particle dispersion is 30 to 150 parts by mass with respect to 100 parts by mass of the metal fine particles or metal oxide fine particles. 3. A method for producing a conductive metal coating according to 2. The conductive particles according to any one of claims 1 to 3, wherein the metal fine particles or metal oxide fine particles have an average particle size of 10 nm or less and a σ / D value (σ: standard deviation, D: average particle size) of 0.2 or less. For producing a conductive metal film. 5. The conductive metal film according to claim 1, wherein the metal is at least one selected from Pt, Pd, Ru, Ag, Fe, Co, Ni, Cu, Mo, In, Ir, Ti, and Al. Manufacturing method. 6. The method for producing a conductive metal film according to claim 1, wherein the fine particle dispersion has a viscosity of 10 Pa · s or less.