JP2004119173A - Ultra-fine particle dispersion liquid and its manufacturing method as well as metal thread or metal film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal ultra-fine particle dispersion liquid in which content of halogen element and alkaline metal is few and its manufacturing method, as well as a metal thin wire or a metal film prepared by using this dispersion liquid. <P>SOLUTION: As for this metal ultra-fine particle dispersion liquid, the content of halogen elements and the alkaline metals is made as 10 ppm or less each. This ultra-fine particle is 100nm or less in particle size and it is in an isolated status, and at least one kind selected from alkylamine, carboxylic acid amide, and amino carboxylic acid salt is dispersed in an organic solvent as a dispersant. It is prepared by using a crucible composed of a material of purity 99.9999% or more by gas evaporation at 10 torr or less. The metal wire and the metal film are prepared from this dispersion liquid. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ultrafine metal particle dispersion, a method for producing the same, and a fine metal wire or metal film. The ultrafine metal particle dispersion is used, for example, in the field of electric and electronic industries and the like, in the field of display devices such as flat panel displays (FPD), and in the field of printed wiring to produce metal wiring and the like.
[0002]
[Prior art]
Conventionally, as a method for producing a conductive metal dispersion liquid composed of ultrafine metal particles of 100 nm or less, a technique using a reduction precipitation method from a metal salt is known (for example, see Patent Document 1). A technique using the method is also known (for example, see Patent Document 2).
[0003]
[Patent Document 1]
JP-A-11-319538 (Claims 1-8, Examples, etc.)
[Patent Document 2]
Japanese Patent No. 25661537 (Claim 3, Example, etc.)
[0004]
[Problems to be solved by the invention]
However, in the case of the above-mentioned reduction precipitation method, in order to add a reducing agent to the reaction system due to its production method, the resulting ultrafine metal particle dispersion contains an alkali metal or a halogen element as an impurity in excess of 10 ppm and 100 ppm or less. Included in the order. Therefore, when a metal wiring or a metal film is formed using the obtained ultrafine metal particle dispersion, there is a problem that a residual alkali metal causes ion migration and that a residual halogen element affects properties such as corrosion resistance. .
[0005]
In addition, an alkali metal or a halogen element from a carbon crucible, an alumina crucible, or the like used in the evaporation process is mixed into the dispersion liquid of ultrafine metal particles produced by a normal gas evaporation method. For this reason, when a metal wiring or a metal film is formed using the obtained ultrafine metal particle dispersion, the residual alkali metal causes ion migration as in the case of the ultrafine metal particle dispersion obtained by the reductive precipitation method. In addition, there is a problem that the residual halogen element affects characteristics such as corrosion resistance.
In recent years, in the field of display devices such as flat panel displays (FPDs) and in the field of printed wiring, fine electrode wiring in fine portions has been required, and therefore, metal superconducting materials with little influence on characteristics such as corrosion resistance have been developed. There is a need to develop fine particle dispersions.
[0006]
Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art by dispersing a metal ultrafine particle dispersion having a small content of an impurity halogen element or an alkali metal, a method for producing the same, and a metal ultrafine particle dispersion. An object of the present invention is to provide a thin metal wire or a metal film manufactured by using the method, in which ion migration is suppressed and characteristics such as corrosion resistance and specific resistance are improved.
[0007]
[Means for Solving the Problems]
The present inventors have focused on the fact that ultrafine metal particles produced by a physical production method, particularly a gas evaporation method, have less impurities than metal ultrafine particle dispersions produced by a reduction precipitation method. As a result, it has been found that impurities are further remarkably reduced by purifying materials such as carbon crucibles and alumina crucibles used in the gas evaporation method, and have completed the present invention.
[0008]
The ultrafine metal particle dispersion of the present invention is a high-purity ultrafine metal particle dispersion, and is characterized in that the content of each of the impurity halogen element and alkali metal is 10 ppm or less. The halogen element is at least one selected from fluorine, chlorine, bromine and iodine, and the alkali metal is at least one selected from sodium, potassium and calcium. The types of the halogen element and the alkali metal differ depending on the crucible to be used, the raw material for producing the ultrafine metal particle dispersion, the production process, and the like. When metal wirings and metal films are prepared using ultrafine metal particle dispersions in which the content of each of the halogen element and the alkali metal is 10 ppm or less, ion migration is suppressed and characteristics such as corrosion resistance and specific resistance are improved. Accordingly, the object of the present invention is solved.
[0009]
The metal ultrafine particle dispersion liquid is a metal ultrafine particle having a particle diameter of 100 nm or less and in an isolated state, in an organic solvent using at least one selected from alkylamines, carboxamides and aminocarboxylates as a dispersant. It is characterized by being dispersed. By setting the particle size to 100 nm or less in an isolated state, a useful metal wiring or the like can be manufactured.
The ultrafine metal particle dispersion is prepared by preparing ultrafine metal particles in a vacuum of 10 torr or less by a gas evaporation method, and a crucible used at that time is made of a material having a purity of 99.9999% or more. It is characterized by the following. If it exceeds 10 torr, good metal ultrafine particles cannot be obtained because the particle diameter increases or aggregates are formed. Further, when the purity of the crucible material is less than 99.9999%, impurities are more likely to be mixed into the manufactured ultrafine metal particles, causing a problem.
[0010]
The production method of the ultrafine metal particle dispersion liquid of the present invention comprises the steps of: using a crucible made of a material having a purity of 99.9999% or more in a vacuum of 10 torr or less using a crucible made of a material having a particle size of 100 nm or less by a gas evaporation method. The metal ultrafine particles are isolated and dispersed in an organic solvent using at least one selected from alkylamines, carboxamides and aminocarboxylates in an isolated state, and the halogen element and alkali impurities It is characterized in that a dispersion of ultrafine metal particles having a metal content of 10 ppm or less is produced. As the organic solvent, all known solvents usually used as a dispersion medium in this field can be used.
[0011]
The thin metal wire or metal film of the present invention is obtained by forming the thin metal wire or film on the substrate to be processed using the above-described ultrafine metal particle dispersion as a printing ink, and then heating and baking to produce an object. It is characterized in that ion migration is suppressed, corrosion resistance is good, and specific resistance is low.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
According to the ultrafine metal particle dispersion of the present invention, as described above, the ultrafine metal particles have a particle diameter of 100 nm or less and are in an isolated state, and are at least one selected from alkylamines, carboxamides, and aminocarboxylates. As a dispersant in an organic solvent.
[0013]
The constituent elements of the metal ultrafine particles are not particularly limited as long as they are conductive metals, and may be appropriately selected according to the purpose and application. For example, in addition to gold, silver, copper, tin, and palladium, at least one selected from many other conductive metals such as nickel, indium, zinc, titanium, chromium, tantalum, tungsten, platinum, iron, cobalt, and silicon. Species metals or alloys of these metals. The dispersant used in the present invention acts on any of the metal ultrafine particles composed of these elements to obtain a desired metal ultrafine particle dispersion.
[0014]
The alkylamine of the dispersant may be a primary to tertiary amine, a monoamine, a diamine, or a triamine. Alkylamines having 4 to 20 carbon atoms in the main chain are preferable, and alkylamines having 8 to 18 carbon atoms in the main chain are more preferable in terms of stability and handling. If the number of carbon atoms in the main chain of the alkylamine is less than 4, the basicity of the amine is too strong, which tends to corrode the metal ultrafine particles, and ultimately dissolves the metal ultrafine particles. Further, when the number of carbon atoms in the main chain of the alkylamine is longer than 20, when the concentration of the ultrafine metal particle dispersion is increased, the viscosity of the dispersion increases and the handling properties become slightly inferior. There is a problem in that carbon tends to remain in the subsequent thin metal wires or metal films, and the specific resistance value increases. In addition, alkylamines of all classes work effectively as dispersants, but primary alkylamines are preferably used in terms of stability and handling properties.
[0015]
Specific examples of the alkylamine include, for example, primary amines such as butylamine, octylamine, dodecylamine, hexadodecylamine, octadecylamine, cocoamine, tallowamine, hydrogenated tallowamine, oleylamine, laurylamine, and stearylamine; Secondary amines such as dicocoamine, dihydrogenated tallowamine, and distearylamine; and dodecyldimethylamine, didodecylmonomethylamine, tetradecyldimethylamine, octadecyldimethylamine, cocodimethylamine, dodecyltetradecyldimethylamine, and Tertiary amines such as trioctylamine and the like, and other diamines such as naphthalenediamine, stearylpropylenediamine, octamethylenediamine, and nonanediamine. There is a down.
[0016]
The content of the alkylamine is usually about 0.1 to 10% by weight, preferably 0.2 to 7% by weight, based on the weight of the ultrafine metal particles. When the content is less than 0.1% by weight, the metal ultrafine particles do not disperse in an independent state, and agglomerates thereof are generated, and there is a problem that dispersion stability is deteriorated, and more than 10% by weight. Then, there is a problem that the viscosity of the obtained dispersion becomes high and a gel-like substance is finally formed.
Specific examples of the above-mentioned carboxylic acid amides and aminocarboxylic acid salts include, for example, stearic acid amide, palmitic acid amide, lauric acid laurate, oleic acid amide, oleic acid diethanolamide, oleic acid laurylamide, stearanilide, oleylaminoethylglycine Etc.
[0017]
According to the present invention, the ultrafine metal particles are prepared by a gas evaporation method in a vacuum of 10 torr or less, and the crucible used at that time is made of a high-purity material having a purity of 99.9999% or more. is there. As the crucible, a zirconia crucible, a magnetic crucible, or the like can be used in addition to the carbon crucible or the alumina crucible.
[0018]
According to the present invention, when the intended ultrafine metal particle dispersion is produced using ultrafine metal particles obtained by a low vacuum gas evaporation method, for example, in the first step, in a vacuum chamber and He or the like, When evaporating the metal charged in the crucible under an atmosphere in which the pressure of the inert gas is 10 Torr or less and cooling and collecting the vapor of the evaporated metal, one or more kinds of Introducing the vapor of the first solvent, bringing the surface of the metal into contact with the vapor of the first solvent at the stage of metal grain growth, and dispersing the obtained primary particles independently and uniformly in a colloidal state in the first solvent. Obtain a liquid. This first solvent is removed in the next second step. The reason why the first solvent is removed in this way is to remove by-products generated when the coexisting first solvent is denatured when the metal vapor evaporated in the first step is condensed. Further, depending on the use of the dispersion, when it is necessary to use an ultrafine particle independent dispersion dispersed in a low-boiling solvent or water or an alcohol-based solvent which is difficult to use in the first step, it is necessary to produce such a dispersion. But also.
[0019]
Next, in a second step, a second solvent, which is a low molecular weight polar solvent, is added to the dispersion obtained in the first step to precipitate ultrafine metal particles contained in the dispersion, and the supernatant liquid is subjected to static treatment. The first solvent used in the first step is removed by a removal method, decantation or the like. This second step is repeated a plurality of times to substantially remove the first solvent.
Finally, in the third step, a new third solvent is added to the sediment obtained in the second step, and the solvent is replaced to obtain a desired metal ultrafine particle dispersion. Thereby, an ultrafine metal particle independent dispersion in which ultrafine metal particles having a particle size of 100 nm or less are dispersed in an independent state is obtained.
[0020]
In the above case, a dispersant can be added in the first step and / or the third step as needed. When added in the third step, a dispersant that does not dissolve in the solvent used in the first step can be used.
In addition, as for the solvent, it is necessary to select a polar solvent such as water, alcohol, or a non-polar hydrocarbon solvent in accordance with the properties of the substrate to be processed such as a glass substrate, a plastic substrate, and a ceramic substrate. In some cases, the conditions for selecting a solvent may be determined depending on the use of the obtained film.
[0021]
For example, the first solvent is a solvent for generating ultrafine metal particles used in the gas evaporation method, and is a solvent having a relatively high boiling point so that it can be easily liquefied when the ultrafine metal particles are cooled and collected. is there. As the first solvent, a solvent containing at least one selected from alcohols having 5 or more carbon atoms, for example, terpineol, citroneole, geraniol, phenethyl alcohol, and the like, or organic esters, for example, benzyl acetate, stearin Any solvent containing at least one selected from ethyl acid, methyl oleate, ethyl phenylacetate, glyceride and the like may be used, and can be appropriately selected depending on the constituent elements of the ultrafine metal particles used or the use of the dispersion.
[0022]
The second solvent may be any solvent that can precipitate the ultrafine metal particles contained in the dispersion obtained in the first step and extract and separate the first solvent to remove it. For example, a low molecular weight polar solvent Acetone.
As the third solvent, a liquid at room temperature, such as a nonpolar hydrocarbon having 6 to 20 carbon atoms in the main chain, water, or an alcohol having 15 or less carbon atoms, can be appropriately selected and used. In the case of non-polar hydrocarbons, if the number of carbon atoms is less than 6, drying is too fast and there is a problem in handling the dispersion, and if the number of carbons exceeds 20, the viscosity of the dispersion tends to increase, Further, when firing, there is a problem that carbon tends to remain. Also in the case of alcohol, when the number of carbon atoms exceeds 15, the viscosity of the dispersion liquid tends to increase, and when firing, there is a problem that carbon tends to remain.
[0023]
As the third solvent, for example, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, octadecane, nonadecane, long-chain alkanes such as eicosane, trimethylpentane, cyclohexane, cycloheptane, Cyclic alkanes such as cyclooctane, aromatic hydrocarbons such as benzene, toluene, xylene, trimethylbenzene and dodecylbenzene, and alcohols such as hexanol, heptanol, octanol, decanol, cyclohexanol and terpineol can be used. These solvents may be used alone or in the form of a mixed solvent. For example, it may be mineral spirit that is a mixture of long-chain alkanes.
The amount of the solvent to be used may be appropriately set according to the use of the ultrafine metal particle dispersion.
The concentration of the ultrafine metal particles can be adjusted as needed by heating in a vacuum after the production of the dispersion.
[0024]
The thin metal wire or metal film of the present invention was prepared by using the above-described ultrafine metal particle dispersion as a printing ink, forming a thin metal wire or film on a substrate to be processed by a known method, and then heating and firing. Things. The printing method is not particularly limited as long as it is a printing method capable of forming a thin metal wire or film. For example, a thin coating or a thin film is drawn on a substrate to be processed by an ordinary coating method or an inkjet method using an inkjet printer. Any method can be used as long as it can be formed by the following method. A thin metal wire or metal film manufactured by heating and baking after formation has characteristics of suppressing ion migration, having good corrosion resistance, and having a low specific resistance value. The heating and firing temperature is preferably, for example, about 200 to 600 ° C.
[0025]
【Example】
Hereinafter, the present invention will be described in detail based on Examples and Comparative Examples.
(Comparative Example 1)
An Ag colloid solution was prepared by a reduction method. A solution obtained by adding 18.9 g of dodecylamine as a dispersant to 400 ml of toluene solvent was placed in a flask, and the mixture was stirred with a stirrer for 1 hour. Thereafter, 185.4 ml of a commercially available silver nitrate aqueous solution (0.5 mol / l) was added with stirring. After stirring for 1 hour, 92.7 ml of a methanol solution of sodium borohydride (NaBH ₄ ) (0.5 mol / l) was added as a reducing agent, and the mixture was further stirred in a 60 ° C water bath for 1 hour. An Ag colloid toluene solution having an average particle size of 10 nm was prepared. Five volumes of acetone were added to one volume of this colloid solution, followed by stirring. Ag particles in the colloidal liquid settled out due to the action of polar acetone. After allowing to stand for 2 hours, the supernatant was removed, and the same amount of acetone as the first time was added again, followed by stirring. After allowing to stand for 2 hours, the supernatant was removed. Tetradecane was newly added to the sediment and stirred. The remaining toluene solvent and acetone were completely removed to prepare an Ag colloid tetradecane solution (1) containing 40% by weight of an Ag colloid having an average particle diameter of 10 nm. This solution contained 500 ppm of Na. The Na content was evaluated by ICP emission spectroscopy.
[0026]
(Comparative Example 2)
When producing ultrafine particles of Ag by the in-gas evaporation method of evaporating Ag by high-frequency induction heating under the condition of a helium gas pressure of 0.5 torr, the Ag ultrafine particles in the production process may contain 20 of α-terpineol and dodecylamine. 1 (volume ratio) is brought into contact, cooled and collected to collect Ag ultrafine particles, and contains 20% by weight of Ag ultrafine particles having an average particle diameter of 5 nm dispersed independently in an α-terpineol solvent. Ag ultrafine particle dispersion was prepared. Five volumes of acetone were added to one volume of this dispersion (colloidal solution) and stirred. Ag fine particles in the dispersion liquid settled out due to the action of polar acetone. After allowing to stand for 2 hours, the supernatant was removed, the same amount of acetone was added as in the beginning, and the mixture was stirred. After allowing to stand for 2 hours, the supernatant was removed. Tetradecane was newly added to the sediment and stirred. The remaining toluene solvent and acetone were completely removed, and an Ag ultrafine particle dispersion liquid (2) containing 40% by weight of Ag ultrafine particles having an average particle diameter of 5 nm was prepared. The amounts of Cl and Na in this dispersion were 18 ppm and 50 ppm, respectively. The amount of Cl in this dispersion was evaluated by ion chromatography, and the amount of Na was evaluated by ICP emission spectroscopy.
[0027]
(Example 1)
In the same manner as in Comparative Example 2, an Ag ultrafine particle dispersion liquid (3) was prepared by a gas evaporation method using a carbon crucible having a purity of 99.9999%. The amounts of Cl and Na in this dispersion were 1 ppm and 2 ppm, respectively.
[0028]
(Example 2)
Using the Ag colloid tetradecane solution (1), the Ag ultrafine particle dispersion liquid (2), and the Ag ultrafine particle dispersion liquid (3) obtained in Comparative Examples 1 and 2 and Example 1, respectively, as inks, a commercially available piezo method was used. Using an inkjet printer having a single nozzle, a thin line having a line / space of 80 μm / 80 μm, a coating thickness of 60 μm, and a length of 100 mm was drawn on a glass substrate for FPD. After the drawing, baking was performed at 300 ° C. for 30 minutes using an electric furnace. As a result, an electrode wiring composed of a thin Ag wire having a width of 80 μm and a thickness of 2.5 μm was produced.
[0029]
This electrode wiring was subjected to an ion migration test under the conditions of a temperature of 60 ° C., a humidity of 90% RH, and a voltage of 120 V. As a result, in the case of the Ag colloid tetradecane solution (1), a whisker-like projection was generated in 30 hours, and a short circuit occurred between the wirings in 200 hours. In the case of the Ag ultrafine particle dispersion liquid (2), a whisker-like projection was generated in 50 hours, and a short circuit occurred between the wirings in 300 hours. In the case of the Ag ultrafine particle dispersion liquid (3), no whisker-like projections were generated even after 300 hours, and no short circuit occurred.
In the case of the electrode wiring obtained using the Ag colloid tetradecane solution (1) and the Ag ultrafine particle dispersion (2), the thin film was peeled off, but the electrode wiring was obtained using the Ag ultrafine particle dispersion (3). In the case of the electrode wiring obtained, the thin wire film did not peel off and the specific resistance was low.
[0030]
(Comparative Example 3)
An Au colloid solution was prepared by a reduction method. A liquid obtained by adding 41.4 g of dodecylamine as a dispersant to 200 ml of a toluene solvent was placed in a flask, and stirred for 1 hour with a stirrer. Thereafter, 101.6 ml of a commercially available aqueous solution of tetrachloroauric acid (III) trihydrate (0.5 mol / l) was added with stirring. After stirring for 1 hour, 101.6 ml of a methanol solution of sodium borohydride (NaBH ₄ ) (0.5 mol / l) was added as a reducing agent, and the mixture was further stirred for 1 hour in a water bath at 60 ° C. An Au colloid toluene solution having an average particle size of 10 nm was prepared. Five volumes of acetone were added to one volume of this colloid solution, followed by stirring. Au particles in the colloidal liquid settled out due to the action of polar acetone. After allowing to stand for 2 hours, the supernatant was removed, and the same amount of acetone as the first time was added again, followed by stirring. After allowing to stand for 2 hours, the supernatant was removed. Tetradecane was newly added to the sediment and stirred. The remaining toluene solvent and acetone were completely removed to prepare an Au colloid tetradecane solution (4) containing 40% by weight of an Au colloid having an average particle diameter of 10 nm. This solution contained 500 ppm of Cl and 500 ppm of Na. The Cl content was evaluated by ion chromatography and the Na content was evaluated by ICP emission spectroscopy.
[0031]
(Comparative Example 4)
The same operation as in Comparative Example 3 was performed using hexylene glycol as a reducing agent instead of NaBH ₄ in Comparative Example 3, and an Au colloid tetradecane solution containing 40% by weight of an Au colloid having an average particle diameter of 10 nm (5) ▼ was prepared. This solution contained 300 ppm of Cl and 10 ppm or less of Na.
[0032]
(Example 3)
When ultrafine particles of Au are generated using an alumina crucible having a purity of 99.9999% by an in-gas evaporation method in which Au is evaporated by high-frequency induction heating under a helium gas pressure of 0.5 Torr, Au ultrafine particles are brought into contact with a vapor of α-terpineol and dodecylamine in a ratio of 20: 1 (volume ratio), collected by cooling and collected, and dispersed independently in an α-terpineol solvent. An Au ultrafine particle dispersion liquid containing 20% by weight of Au ultrafine particles having an average particle diameter of 5 nm was prepared. Five volumes of acetone were added to one volume of this dispersion and stirred. Au particles in the dispersion liquid settled out due to the action of polar acetone. After allowing to stand for 2 hours, the supernatant was removed, the same amount of acetone was added as in the beginning, and the mixture was stirred. After allowing to stand for 2 hours, the supernatant was removed. Tetradecane was newly added to the sediment and stirred. The remaining toluene solvent and acetone were completely removed to prepare an Au ultrafine particle dispersion liquid (6) containing 40% by weight of Au ultrafine particles having an average particle diameter of 5 nm. The Cl and Na contents in this dispersion were each 10 ppm or less.
[0033]
(Example 4)
Using the Au colloid tetradecane solution (4), Au colloid tetradecane solution (5), and Au ultrafine particle dispersion (6) obtained in Comparative Examples 3 and 4 and Example 3 as inks, a commercially available piezo-type single Using an ink jet printer having a nozzle, draw a thin line in the same manner as above, and then bake it at 300 ° C. for 30 minutes using an electric furnace to obtain an electrode wiring consisting of a 50 μm wide and 2.0 μm thick Au fine line. Was prepared.
[0034]
An ion migration test was performed on each of the obtained electrode wires in the same manner as in Example 2. As a result, in the case of the Au ultrafine particle dispersion liquid (6), no whisker-like projections were generated and no short circuit occurred, but in the case of the Au colloid tetradecane solution (4) and the Au colloid tetradecane solution (5), A whisker-like projection was generated, and a short circuit occurred between the wirings. Further, in the case of the electrode wiring obtained using the Au colloid tetradecane solution (4) and the Au colloid tetradecane solution (5), the thin wire film was peeled off, but it was obtained using the Au ultrafine particle dispersion (6). In the case of the electrode wiring, the thin wire film did not peel off.
The specific resistance value of each obtained electrode wiring was 1.0 × 10 ⁻⁴ Ω · cm in the case of Au colloid tetradecane solution ( ⁴ ), and 6.0 × 10 4 in the case of Au colloid tetradecane solution (5). ^Although it was ⁻⁵ Ω · cm, it was as low as 5.0 × 10 ⁻⁶ Ω · cm in the case of the Au ultrafine particle dispersion liquid (6).
[0035]
【The invention's effect】
According to the ultrafine metal particles of the present invention, since the content of the halogen element and the content of the alkali metal as impurities are extremely small, each being 10 ppm or less, the residual alkali metal causes ion migration, and the residual halogen element reduces the corrosion resistance and the like. There is no problem of affecting. For this reason, in the field of display equipment such as a flat panel display, the field of printed wiring, and the like, it is possible to produce fine electrode wiring in a small portion. In this case, the specific resistance value of the obtained electrode wiring is low.

Claims (9)

A dispersion liquid of ultrafine metal particles, wherein the content of each of an impurity halogen element and an alkali metal is 10 ppm or less. The ultrafine metal particle dispersion according to claim 1, wherein the halogen element is at least one selected from fluorine, chlorine, bromine and iodine. 3. The ultrafine metal particle dispersion according to claim 1, wherein the alkali metal is at least one selected from sodium, potassium and calcium. The ultrafine metal particles are dispersed in an organic solvent with at least one selected from alkylamines, carboxamides, and aminocarboxylates as a dispersant in a particle size of 100 nm or less and in an isolated state. The ultrafine metal particle dispersion according to any one of claims 1 to 3. The metal ultrafine particles are prepared by a gas evaporation method in a vacuum of 10 torr or less, and the crucible used at that time is made of a material having a purity of 99.9999% or more. 5. The ultrafine metal particle dispersion according to any one of 1 to 4. The ultrafine metal particle dispersion according to claim 5, wherein the crucible is a carbon crucible, an alumina crucible, a zirconia crucible, or a magnetic crucible. Ultrafine metal particles having a particle size of 100 nm or less are produced by a gas evaporation method using a crucible made of a material having a purity of 99.9999% or more in a vacuum of 10 torr or less. A metal which is dispersed in an organic solvent by using at least one selected from an amine, a carboxylic acid amide and an amino carboxylate as a dispersant, and the content of a halogen element and an alkali metal as impurities is 10 ppm or less, respectively. A method for producing an ultrafine metal particle dispersion, which comprises producing an ultrafine particle dispersion. A metal fine wire is formed on a substrate to be processed using the ultrafine metal particle dispersion according to any one of claims 1 to 6 as a printing ink, and then heated and fired to produce a metal fine wire. A thin metal wire characterized in that migration is suppressed, corrosion resistance is good, and specific resistance is low. A metal film is formed on a substrate to be processed using the ultrafine metal particle dispersion according to any one of claims 1 to 6 as a printing ink, and then heated and fired to form a metal film. A metal film characterized in that migration is suppressed, corrosion resistance is good, and specific resistance is low.