JP2016039008A - Method for manufacturing copper-layer attached substrate, and copper-layer attached substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a copper-layer attached substrate in which the process is simplified and in which it is possible to make the substrate into a conductor at a lower temperature.SOLUTION: Provided is a method for manufacturing a copper-layer attached substrate including: a step for forming a conductive material-containing layer on a substrate by applying a conductive material comprising a copper-containing particle having a copper-containing core particle and organic matter, disposed in at least a portion of the surface of said core particle, having an amino group, and a dispersion medium; and a step for forming the copper layer by heat treating, under an atmosphere comprising acid that can be introduced as saturation gas and in which the oxygen concentration is 1 ppm to 10000 ppm, the conductive material-containing layer, at a temperature range of 150°C or less.SELECTED DRAWING: None

Description

  The present invention relates to a method for manufacturing a substrate with a copper layer, and a substrate with a copper layer.

  As a method for forming a metal pattern, a step of applying a conductive material such as ink or paste containing metal particles such as copper onto a substrate by ink jet printing, screen printing or the like, and heating the conductive material to sinter the metal particles, There is known a method including a conductor-forming step for developing conductivity.

  From the viewpoint of imparting printability to the conductive material, a binder resin or the like is generally added to the conductive material. Moreover, an organic dispersing agent may be added to a conductive material from a viewpoint of improving the dispersibility of the metal particle in conductive materials, such as a paste. Furthermore, when the metal particles are copper particles, a protective agent may be used because copper is a substance that is easily oxidized. Organic components such as a binder resin, an organic dispersant, and a protective agent are factors that inhibit the sintering of metal particles in the conductor process. Therefore, in order to obtain a conductor having a low volume resistivity, it is necessary to remove organic components, and the conductor-forming step is performed at a high temperature in an oxygen atmosphere, and these organic components are burned and removed.

  On the other hand, from the viewpoints of improving production efficiency and diversifying the types of substrates to be used, there is a need for the development of a technique that enables conductive materials to be made conductive at lower temperatures (for example, 150 ° C. or lower). Further, since copper easily becomes copper oxide by heating in an oxygen atmosphere, there is a complicated process of sintering in a reducing atmosphere after removing organic components.

  Therefore, in order to suppress the oxidation of copper and improve the storage stability, one in which an organic substance as a coating material is attached to the surface of copper particles is known. For example, Patent Document 1 describes a coated copper particle that can be sintered at a low temperature and exhibits good conductivity and a method for producing the same. The copper particles described in Patent Document 1 are obtained by mixing a copper precursor such as copper oxalate and a reducing compound such as hydrazine to obtain a composite compound, and heating the composite compound in the presence of an alkylamine. It is manufactured by the method which has these. In the example of Patent Document 1, the ink containing the produced copper particles is heated to 300 ° C. at 60 ° C./min in an argon atmosphere and held for 30 minutes to achieve a conductor.

  Patent Document 2 describes a conductive paste composition containing a conductive metal powder, an organic vehicle, and the like. For the purpose of removing the organic binder, the organic vehicle is usually burned by performing heat treatment at 250 ° C. to 330 ° C. in an air atmosphere, a nitrogen atmosphere, etc., and then in a neutral or reducing atmosphere so that the metal powder is not oxidized. Sintering at 1300 ° C. is described.

JP 2012-72418 A JP 2012-226865 A

  In recent years, from the viewpoint of improving production efficiency and diversifying the types of substrates to be used, there is a demand for the development of a technique that enables metal particles to be made conductive at a lower temperature (for example, 150 ° C. or lower). Moreover, the simplicity of the conductor process is required. Accordingly, there is a need for the development of a conductorization method that can be easily performed at a temperature lower than the temperatures described in Patent Documents 1 and 2.

  An object of this invention is to provide the board | substrate with a copper layer obtained by the manufacturing method of the board | substrate with a copper layer in which a process is simplified and conductorization at lower temperature is possible in view of the said subject, and this.

Means for solving the above problems are as follows.
<1> A conductive material containing copper-containing particles having a core particle containing copper and an organic substance having an amino group disposed on at least a part of the surface of the core particle and a dispersion medium is provided on the substrate. Forming a conductive material-containing layer
Forming a copper layer by heat-treating the conductive material-containing layer in a temperature range of 150 ° C. or lower in an atmosphere containing an acid that can be introduced as a saturated gas and having an oxygen concentration of 1 ppm to 10,000 ppm;
The manufacturing method of the board | substrate with a copper layer containing this.

The content rate of the organic substance which has an amino group in the <2> said copper containing particle | grain is 0.1 mass%-20 mass%, The manufacturing method of the board | substrate with a copper layer as described in said <1>.

<3> The method for producing a substrate with a copper layer according to <1> or <2>, wherein the organic substance having an amino group has an alkyl group having 7 or less carbon atoms.

<4> The method for producing a substrate with a copper layer according to any one of <1> to <3>, wherein the content of the copper oxide in the core particles is 5% by mass or less.

<5> The board | substrate with a copper layer obtained by the manufacturing method of any one of said <1>-<4>.

<6> a substrate;
A sintered material of a conductive material containing copper-containing particles and a dispersion medium having copper-containing core particles and an amino group-containing organic substance arranged on at least part of the surface of the core particles, which are disposed on the substrate A copper layer,
A substrate with a copper layer.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the board | substrate with a copper layer which can simplify a process and can be made into a conductor at lower temperature, and the board | substrate with a copper layer obtained by this can be provided.

  In the present specification, a numerical range indicated using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. Further, in the present specification, the content of each component in the composition is the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition. Means.

  In this specification, the term “process” is not limited to an independent process, and is included in the term if the intended purpose of the process is achieved even when it cannot be clearly distinguished from other processes. .

  In this specification, the term “layer” includes a configuration formed in a part in addition to a configuration formed in the entire surface when observed as a plan view.

  In the present specification, the term “conducting” means that the metal-containing particles are sintered to be changed into a conductive object. “Conductor” refers to an object having electrical conductivity. Conductivity means that the volume resistivity is 300 μΩcm or less.

<Method for producing substrate with copper layer>
The manufacturing method of the board | substrate with a copper layer of this invention has an amino group arrange | positioned on the at least one part of the surface of the core particle (henceforth a "core particle") containing the copper and the said core particle on a board | substrate. A step of forming a conductive material-containing layer by applying a conductive material containing copper-containing particles having organic matter and a dispersion medium (hereinafter also referred to as “conductive material application step”), an acid that can be introduced as a saturated gas, and And a step of forming a copper layer by heat-treating the conductive material-containing layer in a temperature range of 150 ° C. or lower in an atmosphere having an oxygen concentration of 1 ppm to 10000 ppm (hereinafter also referred to as “heat treatment step”). The manufacturing method of the electroconductive laminated body of this invention may include the other process as needed.

  The manufacturing method of the conductive laminate according to the present invention adopts the above-described configuration, thereby simplifying the process and making the conductor at a lower temperature. Thereby, a copper layer can be formed also on a board | substrate with comparatively low heat resistance. The reason is guessed as follows.

  Copper is easily oxidized. However, since at least a part of the surface of the copper-containing particles according to the present invention is coated with an organic substance, there is an advantage that oxidation is suppressed even when stored in the atmosphere.

In addition, since the heat treatment step is performed in an atmosphere having an oxygen concentration of 1 ppm or more, the organic matter that hinders conductorization is removed by thermal decomposition when sintering. And the presence of oxygen accelerates the thermal decomposition of organic matter, and can lower the heat treatment temperature. Moreover, unnecessary oxidation of copper is suppressed by being executed in an atmosphere having an oxygen concentration of 10,000 ppm or less. Furthermore, by further containing an acid that can be introduced as a saturated gas in an atmosphere having an oxygen concentration of 10,000 ppm or less, a conductor can be realized at a lower heat treatment temperature. The reason for this is not clear, but it is presumed that the acid promotes the detachment and decomposition of organic substances arranged on the surface of the copper-containing particles.
In the examples described in Patent Document 1, there is no specific description about the oxygen concentration in the atmosphere during heating, and heating is performed at a maximum temperature of 300 ° C. in order to sufficiently decompose the organic matter. Yes.

  Moreover, since oxidation is suppressed in the copper-containing particles in the present invention, the content of copper oxide is reduced as compared with conventional copper-containing particles, and even if it contains a small amount of copper oxide, it contains an acid. By being heat-treated in an atmosphere, the copper oxide is reduced to produce metallic copper. Therefore, a lower resistance copper layer (conductor) is obtained. In addition, since the pyrolysis of the organic substance and the reduction to metallic copper are performed at once, the process can be simplified.

  As described above, according to the manufacturing method of the present invention, conductorization at a lower temperature is realized, and the reduction process is not required after the thermal decomposition process of the organic matter, thereby simplifying the process.

[Conductive material application process]
In the conductive material application step according to the present invention, the substrate contains copper-containing particles having a copper-containing core particle and an organic substance having an amino group disposed on at least a part of the surface of the core particle, and a dispersion medium. A conductive material is provided to form a conductive material-containing layer.

(substrate)
The material of the substrate is not particularly limited, and may or may not have conductivity. For example, metals such as Cu, Au, Pt, Pd, Ag, Zn, Ni, Co, Fe, Al, Sn, alloys of these metals, semiconductors such as ITO, ZnO, SnO, Si, glass, graphite, graphite, etc. A carbon material, resin, paper, etc. can be mentioned.

The method for producing a conductive laminate of the present invention can be suitably applied particularly when a substrate made of a material having relatively low heat resistance is used. An example of such a material is a thermoplastic resin. Examples of the thermoplastic resin include polyolefin resins such as polyethylene, polypropylene, and polymethylpentene, and polycarbonate resins.
The shape of the substrate is not particularly limited, and may be a plate shape, a rod shape, a roll shape, a film shape, or the like.

(Conductive material)
The conductive material used in the method for producing a conductive laminate of the present invention is a copper-containing particle having core particles containing copper and an organic substance having an amino group arranged on at least a part of the surface of the core particles, And a dispersion medium, and may contain other components as necessary.

-Copper-containing particles-
In the copper-containing particles in the present invention, an organic substance having an amino group (hereinafter sometimes abbreviated as “organic substance”) is disposed on at least a part of the surface of the core particle containing copper. When at least a part of the surface of the core particle is coated with an organic substance, the oxidation of the copper-containing particle is suppressed, and the copper-containing particle that can be stored for a long time in the air can be obtained.

  From the viewpoint of more effectively suppressing the oxidation of the copper-containing particles, the organic content is preferably 0.1% by mass or more, more preferably 0.2% by mass or more in the copper-containing particles. More preferably, the content is 0.3% by mass or more. From the viewpoint of achieving a conductor at a lower temperature, the content of the organic substance is preferably 20% by mass or less, more preferably 10% by mass or less in the copper-containing particles, and 5% by mass or less. Is more preferable.

  The content of the organic substance is obtained by heating the copper-containing particles at a temperature equal to or higher than the temperature at which the organic substance is thermally decomposed, and comparing the mass before and after the heating.

In a preferred embodiment of the present invention, the organic substance having an amino group includes a substance having an alkyl group having 7 or less carbon atoms and derived from an alkylamine. Alkylamine is a primary amine represented by RNH ₂ (R is a hydrocarbon group and may be cyclic or branched), R ₁ R ₂ NH (R ₁ and R ₂ are the same or different. Or a branched or branched hydrocarbon group), an alkylene diamine in which two amino groups are substituted on the hydrocarbon chain, and the like. The alkylamine may have one or more double bonds, and may have atoms such as oxygen, silicon, nitrogen, sulfur, and phosphorus. The alkylamine may be only one type or two or more types.

  Specific examples of the primary amine used in the method of the present invention include ethylamine, 2-ethoxyethylamine, propylamine, butylamine, isobutylamine, pentylamine, isopentylamine, hexylamine, cyclohexylamine, heptylamine, and octylamine. , Nonylamine, decylamine, dodecylamine, hexadecylamine, oleylamine and the like.

  Specific examples of the secondary amine used in the method of the present invention include diethylamine, dipropylamine, dibutylamine, ethylpropylamine, ethylpentylamine, dibutylamine, dipentylamine, and dihexylamine.

  Specific examples of the alkylene diamine used in the method of the present invention include ethylene diamine, N, N-dimethylethylene diamine, N, N′-dimethylethylene diamine, N, N-diethyl ethylene diamine, N, N′-diethyl ethylene diamine, 1, 3-propanediamine, 2,2-dimethyl-1,3-propanediamine, N, N-dimethyl-1,3-diaminopropane, N, N′-dimethyl-1,3-diaminopropane, N, N-diethyl -1,3-diaminopropane, 1,4-diaminobutane, 1,5-diamino-2-methylpentane, 1,6-diaminohexane, N, N′-dimethyl-1,6-diaminohexane, , 7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,12-diaminododecane, etc. It is possible.

  The hydrocarbon group of the alkylamine preferably has 7 or less carbon atoms. Alkylamines having a carbon number of 7 or less (specific alkylamines) have a relatively low molecular weight, and therefore tend to thermally decompose even at relatively low temperatures. From the viewpoint of achieving better conductorization, the hydrocarbon group of the alkylamine preferably has 6 or less carbon atoms. Further, the hydrocarbon group of the alkylamine preferably has 4 or more carbon atoms.

  Specific examples of primary amines having 7 or less carbon atoms include ethylamine, 2-ethoxyethylamine, propylamine, butylamine, isobutylamine, pentylamine, isopentylamine, hexylamine, cyclohexylamine, heptylamine and the like. Can do.

  Specific examples of the secondary amine having 7 or less carbon atoms include diethylamine, dipropylamine, dibutylamine, ethylpropylamine, and ethylpentylamine.

  Specific examples of the alkyldiamine having 7 or less carbon atoms include ethylenediamine, N, N-dimethylethylenediamine, N, N′-dimethylethylenediamine, N, N-diethylethylenediamine, N, N′-diethylethylenediamine, 1,3 -Propanediamine, 2,2-dimethyl-1,3-propanediamine, N, N-dimethyl-1,3-diaminopropane, N, N'-dimethyl-1,3-diaminopropane, N, N-diethyl- 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diamino-2-methylpentane, 1,6-diaminohexane, N, N′-dimethyl-1,6-diaminohexane, 1, Examples thereof include 7-diaminoheptane.

  The shape of the copper-containing particles in the present invention is not particularly limited. For example, a spherical shape, a long granular shape, a flat shape, and the like can be mentioned, which can be selected according to the use of the copper-containing particles. From the viewpoint of preparing a printing paste, it is preferably spherical or long granular.

  The size of the copper-containing particles in the present invention is not particularly limited and can be selected according to the application. The median length of the long axis of 200 randomly selected copper-containing particles is preferably in the range of 10 nm to 500 nm, more preferably in the range of 10 nm to 200 nm, and 10 nm to 100 nm. More preferably, it is in the range. When the median value of the major axis length of 200 randomly selected copper-containing particles is 10 nm or more, the reactivity is lower than that of particles having the value less than 10 nm. In the oxygen concentration range, oxidation tends to be suppressed better.

  In the present invention, the length of the major axis means the distance between two planes selected so that the distance between the two planes circumscribing the particle and parallel to each other is maximized. In the present invention, the median value of the length of the major axis is the two values (100th and 101st) located at the center when the major axis length values of 200 copper-containing particles are arranged in ascending order. Means the arithmetic mean. The length of the major axis of the copper-containing particles can be measured by a usual method such as observation with an electron microscope.

  The copper containing particle | grains in this invention contain the organic substance which has a metallic copper and an amino group at least, and may contain another substance as needed. Examples of other substances include metals such as gold, silver, platinum, tin, and nickel or compounds containing these metal elements, fatty acid copper, reducing compounds, copper oxides, and copper chlorides described later. From the viewpoint of forming a copper pattern with excellent conductivity, the content of metallic copper in the copper-containing particles is preferably 50% by mass or more, more preferably 60% by mass or more, and 70% by mass or more. More preferably it is.

  In the copper-containing particles according to the present invention, since an organic substance having an amino group is present on at least a part of the surface of the core particles, oxidation is suppressed, and the content of copper oxide is small. For example, in a certain embodiment, the content rate of the copper oxide in a core particle is 5 mass% or less. The content rate of the copper oxide in the core particle can be measured by, for example, an X-ray diffraction spectrum (XRD, X-ray diffraction). The content rate of the copper oxide in a core particle is a value when measured before conductorization.

-Method for producing copper-containing particles-
The method for producing the copper-containing particles according to the present invention is not particularly limited. In a preferred embodiment of the present invention, a composition comprising a metal salt of a fatty acid having a carbon number of 9 or less and copper, a reducing compound, and an alkylamine containing an alkylamine having a carbon number of 7 or less. The copper-containing particles according to the present invention can be produced by a method having a heating step.

  The method uses a metal salt of fatty acid and copper having 9 or less carbon atoms as a copper precursor. This makes it possible to use an alkylamine having a lower boiling point (that is, having a lower molecular weight) as a reaction medium than the method described in Patent Document 1 using silver oxalate or the like as a copper precursor. It is done. As a result, the organic substance present on the surface of the obtained copper-containing particles is more likely to be thermally decomposed, and it is considered that the conductorization can be performed at a low temperature.

-Fatty acid-
The fatty acid used in the above method is a monovalent carboxylic acid represented by RCOOH (R is a chain hydrocarbon group, which may be linear or branched). The fatty acid used in the present invention may be either a saturated fatty acid or an unsaturated fatty acid. From the viewpoint of obtaining a good coating of the core particles, linear saturated fatty acids are preferred. Only one type or two or more types of fatty acids may be used.

  From the viewpoint of obtaining good sintering at a low temperature, the fatty acid preferably has 9 or less carbon atoms. Examples of saturated fatty acids having 9 or less carbon atoms include acetic acid (2 carbon atoms), propionic acid (3 carbon atoms), butyric acid and isobutyric acid (4 carbon atoms), valeric acid and isovaleric acid (5 carbon atoms), capron Examples include acids (carbon number 6), enanthic acid and isoenanthic acid (carbon number 7), caprylic acid, isocaprylic acid and isocaproic acid (carbon number 8), nonanoic acid and isononanoic acid (carbon number 9). Examples of the unsaturated fatty acid having 9 or less carbon atoms include those having one or more double bonds in the hydrocarbon group of the saturated fatty acid.

  The type of fatty acid used in the production of the copper-containing particles in the present invention can affect properties such as dispersibility of the obtained copper-containing particles in a dispersion medium and sinterability. For this reason, it is preferable to select the kind of fatty acid according to the use of copper-containing particles. From the viewpoint of achieving both dispersibility in a dispersion medium and conductorization at low temperature, it is preferable to use a fatty acid having 5 to 9 carbon atoms and a fatty acid having 4 or less carbon atoms in combination. For example, nonanoic acid having 9 carbon atoms and acetic acid having 2 carbon atoms are preferably used in combination.

  The ratio in the case of using together the fatty acid having 5 to 9 carbon atoms and the fatty acid having 4 or less carbon atoms is not particularly limited. In addition, when the ratio of the fatty acid having 4 or less carbon atoms in the fatty acid having 9 or less carbon atoms is less than 40 mol%, long-shaped copper-containing particles extending in one direction can be stably produced. be able to. On the other hand, when the proportion of fatty acids having 4 or less carbon atoms is 40 mol% or more, the shape tends to be controlled in a spherical shape.

  The method for obtaining a salt compound (fatty acid copper) of fatty acid and copper having 9 or less carbon atoms is not particularly limited. For example, it may be obtained by mixing copper hydroxide and a fatty acid in a solvent, or commercially available fatty acid copper may be used. Alternatively, by mixing copper hydroxide, a fatty acid and a reducing compound in a solvent, the production of fatty acid copper and the formation of a complex formed between the fatty acid copper and the reducing compound can be performed collectively. Good.

-Reducing compound-
The reducing compound used in the above method is considered to form a complex compound such as a complex between both compounds when mixed with fatty acid copper. As a result, the reducing compound becomes an electron donor to the copper ion in the fatty acid copper, and the reduction of the copper ion is likely to occur, and the liberation of copper atoms due to spontaneous pyrolysis than the fatty acid copper in a state where no complex is formed. This is likely to occur. A reducing compound may be used individually by 1 type, or may use 2 or more types together.

  Specific examples of reducing compounds include hydrazine, hydrazine derivatives, hydrazine hydrochloride, hydrazine sulfate, hydrazine hydrate and other hydrazine compounds, hydroxylamine, hydroxylamine derivatives such as hydroxylamine compounds, sodium borohydride, sodium sulfite, hydrogen sulfite. Examples thereof include sodium compounds such as sodium, sodium thiosulfate, and sodium hypophosphite.

  A reducing compound having an amino group is preferable from the viewpoints of easily forming a coordination bond to a copper atom in fatty acid copper, and easily forming a complex while maintaining the structure of fatty acid copper. Examples of the reducing compound having an amino group include hydrazine and derivatives thereof, hydroxylamine and derivatives thereof, and the like.

  From the viewpoint of lowering the heating temperature (for example, 150 ° C. or lower) in the step of heating the composition containing fatty acid copper, the reducing compound and the alkylamine in the method (hereinafter also referred to as the heating step), the evaporation of the alkylamine or It is preferable to select a reducing compound capable of forming a complex that causes reduction and liberation of a copper atom in a temperature range that does not cause decomposition. Examples of such reducing compounds include hydrazine and its derivatives, hydroxylamine and its derivatives, and the like. These reducing compounds can form a complex by forming a coordinate bond with a copper atom by a nitrogen atom forming a skeleton. In addition, since these reducing compounds generally have a stronger reducing power than alkylamines, the resulting complexes tend to spontaneously decompose under relatively mild conditions, and tend to reduce and release copper atoms.

  By selecting a suitable one of these derivatives instead of hydrazine or hydroxylamine, the reactivity with the fatty acid copper can be adjusted, and a complex that generates spontaneous decomposition under a desired condition can be generated. Examples of hydrazine derivatives include methyl hydrazine, ethyl hydrazine, n-propyl hydrazine, isopropyl hydrazine, n-butyl hydrazine, isobutyl hydrazine, sec-butyl hydrazine, t-butyl hydrazine, n-pentyl hydrazine, isopentyl hydrazine, and neo-pentyl hydrazine. , T-pentylhydrazine, n-hexylhydrazine, isohexylhydrazine, n-heptylhydrazine, n-octylhydrazine, n-nonylhydrazine, n-decylhydrazine, n-undecylhydrazine, n-dodecylhydrazine, cyclohexylhydrazine, phenyl Examples include hydrazine, 4-methylphenylhydrazine, benzylhydrazine, 2-phenylethylhydrazine, 2-hydrazinoethanol, and acetohydrazine. Rukoto can. Examples of hydroxylamine derivatives include N, N-di (sulfoethyl) hydroxylamine, monomethylhydroxylamine, dimethylhydroxylamine, monoethylhydroxylamine, diethylhydroxylamine, N, N-di (carboxyethyl) hydroxylamine and the like. Can do.

  The ratio of the copper and the reducing compound contained in the fatty acid copper is not particularly limited as long as a desired complex is formed. For example, the ratio (copper: reducing compound) can be in the range of 1: 1 to 1: 4 on a molar basis, preferably in the range of 1: 1 to 1: 3, and 1: 1 to 1 : The range of 2 is more preferable.

-Alkylamine-
The alkylamine used in the above method is considered to function as a reaction medium for the decomposition reaction of the complex formed from the fatty acid copper and the reducing compound. Furthermore, it is considered that protons generated by the reducing action of the reducing compound are captured, and the reaction solution is inclined to be acidic and copper atoms are prevented from being oxidized.

  The alkylamine is similar to that described in connection with the organic matter present on the surface of the copper-containing particles of the present invention. When the alkylamine contains an alkylamine other than the specific alkylamine (alkylamine having 7 or less carbon atoms), the proportion of the specific alkylamine in the total alkylamine is preferably 50% by mass or more, and 60% by mass or more. It is more preferable that it is 70 mass% or more.

  The ratio of copper and alkylamine contained in fatty acid copper is not particularly limited as long as desired copper-containing particles are obtained. For example, the ratio (copper: alkylamine) can be in a range of 1: 1 to 1: 8 on a molar basis, preferably in a range of 1: 1 to 1: 6, and 1: 1 to 1: A range of 4 is more preferable.

-Heating process-
In the said method, the method in particular for implementing the process of heating the composition containing fatty-acid copper, a reducing compound, and an alkylamine is not restrict | limited. For example, a method of heating a composition obtained by adding alkylamine after mixing fatty acid copper and a reducing compound, and a composition obtained by adding reducing compound after mixing fatty acid copper and alkylamine Examples thereof include a method of heating, a method of heating a composition obtained by mixing copper hydroxide, a fatty acid, a reducing compound and an alkylamine, which are starting materials for fatty acid copper.

  The composition containing fatty acid copper, reducing compound and alkylamine is heated at a temperature at which a complex formed from fatty acid copper and the reducing compound is decomposed. For example, the heating is preferably performed at 150 ° C. or less, more preferably at 130 ° C. or less, and further preferably at 100 ° C. or less. In the said method, a heating process can be performed at comparatively low temperature by using specific fatty acid copper as a copper precursor.

  The composition containing fatty acid copper, a reducing compound and an alkylamine may further contain a solvent. From the viewpoint of promoting the formation of a complex of fatty acid copper and a reducing compound, it is preferable to include a polar solvent. Here, the polar solvent is preferably a solvent having solubility in water at 25 ° C., and more preferably an alcohol solvent. The reason why the formation of the complex is promoted by using alcohol as the solvent is not clear, but it is considered that the contact with the water-soluble reducing compound is promoted while dissolving the solid fatty acid copper. A solvent may be used individually by 1 type, or may use 2 or more types together.

  As alcohol which shows the solubility with respect to water at 25 degreeC, C1-C8 can be mentioned and the alcohol which has one hydroxyl group in a molecule | numerator can be mentioned. Examples of such alcohols include linear alkyl alcohols, phenols, and those obtained by replacing hydrogen atoms of hydrocarbons having an ether bond in the molecule with hydroxyl groups. From the viewpoint of expressing a stronger polarity, an alcohol having two or more hydroxyl groups in the molecule is also preferably used. Moreover, you may use alcohol containing a sulfur atom, a phosphorus atom, a silicon atom, etc. according to the use of the copper containing particle | grains manufactured.

  Specific examples of alcohol used as a solvent include methanol, ethanol, 1-propanol, 2-propanol, butanol, pentanol, hexanol, heptanol, octanol, allyl alcohol, benzyl alcohol, pinacol, propylene glycol, menthol, catechol, hydroquinone, Examples include salicyl alcohol, glycerin, pentaerythritol, sucrose, glucose, xylitol, methoxyethanol, triethylene glycol monomethyl ether, ethylene glycol, triethylene glycol, tetraethylene glycol, and pentaethylene glycol.

  Among the alcohols, methanol, ethanol, 1-propanol and 2-propanol having a very high solubility in water are preferable, 1-propanol and 2-propanol are more preferable, and 1-propanol is more preferable.

(Dispersion medium)
The dispersion medium used for the conductive material in the present invention is not particularly limited, and can be selected from organic solvents generally used for producing conductive inks, conductive pastes, and the like according to applications. For example, terpineol, isobornylcyclohexanol, dihydroterpineol, dihydroterpineol acetate and the like are preferable from the viewpoint of viscosity control.

(Other ingredients)
In addition to the above-described components, the conductive material in the present invention can further contain other components that are usually used in the technical field, if necessary. Examples of other components include thixotropic agents, plasticizers, dispersants, surfactants, inorganic binders, metal oxides, ceramics, thixotropic agents, and organometallic compounds.

(Method for producing conductive material)
The manufacturing method of the electrically conductive material in this invention is not specifically limited, The method normally used in the said technical field can be used.
For example, it can prepare by disperse | distributing the copper containing particle | grains in this invention, and the other component contained as needed in a dispersion medium. Dispersion treatment includes Ishikawa-type stirrer, rotation-revolution stirrer, ultra-thin high-speed rotary disperser, roll mill, ultrasonic disperser, media disperser such as bead mill, homomixer, cavitation stirrer such as Silverson stirrer, Ultema An opposing collision method such as Iser can be used. Moreover, you may use combining these methods suitably.

  The state of the conductive material of the present invention is not particularly limited and can be selected according to the application. For example, when the conductive material is applied to the screen printing method, the viscosity is preferably 0.1 Pa · s to 30 Pa · s, and more preferably 1 Pa · s to 30 Pa · s. When the conductive material is applied to the ink jet printing method, the viscosity is preferably 0.1 mPa · s to 30 mPa · s, and more preferably 5 mPa · s to 20 mPa · s.

(Method for applying conductive material)
The method for forming the conductive material-containing layer by applying the conductive material on the substrate is not particularly limited as long as the conductive material-containing layer can be formed in any shape at any location on the substrate. Examples of such methods include inkjet methods, super inkjet methods, screen printing methods, transfer printing methods, offset printing methods, jet printing methods, dispenser methods, jet dispenser methods, needle dispenser methods, comma coating methods, slit coating methods, and die coating methods. , Gravure coating method, letterpress printing method, intaglio printing method, gravure printing method, soft lithographic method, dip pen lithographic method, particle deposition method, spray coating method, spin coating method, dip coating method, electrodeposition coating method, etc. Can do. Among them, at least selected from the group consisting of an inkjet method, a super inkjet method, a screen printing method, an offset printing method, a jet printing method, a dispenser method, a needle dispenser method, a comma coating method, a slit coating method, a die coating method, and a gravure coating method. One method is preferred.
For example, a paste-like conductive material may be applied to the substrate by a screen printing method, and an ink-like conductive material may be applied to the substrate by an inkjet printing method.

(Characteristics of conductive material containing layer)
The shape of the conductive material-containing layer formed on the substrate is not particularly limited and can be appropriately selected according to the purpose.
Further, the thickness of the conductive material-containing layer is not particularly limited and can be appropriately selected according to the purpose. For example, the thickness may be 0.2 μm to 50 μm, and is preferably 0.5 μm to 20 μm from the viewpoint of conductivity and connection reliability.

<Heat treatment process>
In the heat treatment step, the conductive material-containing layer formed in the conductive material application step is heat treated in a temperature range of 150 ° C. or lower in an atmosphere containing an acid that can be introduced as a saturated gas and having an oxygen concentration of 1 ppm to 10,000 ppm. Form a layer.

  In the present invention, the conductor concentration at a lower temperature tends to be achieved by slightly increasing the oxygen concentration compared to the case where the conventional conductive material is made a conductor. The reason for this is not clear, but the copper-containing particles of the present invention have the property of being less susceptible to oxidation than conventional copper-containing particles, so the organic concentration is increased by suppressing the excessive oxidation of the copper-containing particles and increasing the oxygen concentration. It is considered that the thermal decomposition of can be promoted. However, if the oxygen concentration is too high, the oxidation of the copper-containing particles is promoted, so that the temperature for making the conductor becomes high. For this reason, the upper limit value of the oxygen concentration is set to 10,000 ppm. In addition, by conducting at an oxygen concentration in the above range, unnecessary oxidation of copper can be suppressed, and a reduction step can be omitted after the thermal decomposition step of the organic matter, and complicated operations can be omitted.

  Furthermore, by making the oxygen concentration within the above specific range and adding an acid that can be introduced as a saturated gas such as formic acid, the temperature for making the conductor can be lowered. Although the reason is not clear, it is thought that it is because desorption and decomposition | disassembly of the organic substance arrange | positioned on the surface of a copper containing particle | grain is accelerated | stimulated.

  The oxygen concentration in the heat treatment step is preferably 10 ppm to 5000 ppm, more preferably 10 ppm to 1000 ppm.

  The atmosphere in the heat treatment step further includes an acid that can be introduced as a saturated gas in addition to oxygen. When the copper-containing particles contain copper oxide, the copper oxide is reduced by heating in an atmosphere containing an acid that can be introduced as a saturated gas, thereby producing metallic copper. Examples of the acid that can be introduced as the saturated gas include formic acid and acetic acid.

  The concentration of the acid in the atmosphere of the heat treatment step is preferably 1 ppm to 10000 ppm, and more preferably 10 ppm to 5000 ppm.

  An inert gas can be used in the atmosphere in the heat treatment step. Examples of the inert gas include nitrogen gas, argon gas, and helium gas.

As described above, the conductive material according to the present invention can be made into a conductor at a relatively low temperature. Specifically, for example, the conductor can be formed at 150 ° C. or lower. Therefore, for example, it can be suitably used when a copper wiring is formed on a substrate having low heat resistance such as resin.
The heat treatment step may be performed at a constant rate of temperature increase or irregularly.
The heat treatment time is not particularly limited, and can be selected in consideration of the heat treatment temperature, the heat treatment atmosphere, the amount of copper-containing particles, and the like. The heat treatment time is preferably 10 minutes to 120 minutes from the viewpoint of process control.

<Other processes>
The manufacturing method of the board | substrate with a copper layer of this invention may also include another process as needed. Examples of other steps include a step of reducing copper oxide after the heat treatment step, a step of removing residual components by light baking after the heating step, a step of applying a load after the heating step, and the like.

[Substrate with copper layer]
The substrate with a copper layer of the present invention includes a substrate, a copper-containing core particle disposed on the substrate, and an organic substance having an amino group disposed on at least a part of the surface of the core particle. And a copper layer that is a sintered product of a conductive material containing particles and a dispersion medium.
The board | substrate with a copper layer of this invention is obtained by the manufacturing method of the board | substrate with a copper layer of this invention. That is, the board | substrate with a copper layer of this invention has a board | substrate and the copper layer on the said board | substrate, and the said copper layer is a sintered compact of the above-mentioned electrically-conductive material.

  Since the board | substrate with a copper layer obtained by the manufacturing method of this invention can be manufactured by heat processing lower temperature than before, there is little damage to a board | substrate. Therefore, for example, it can be suitably used when a copper wiring is formed on a substrate having low heat resistance such as resin.

  Moreover, since the conductor (copper layer) in the present invention is a sintered product of a conductive material applied on a substrate, it can be used as an additive compared to a conductor formed by a plating method or the like. The amount of impurities is small and the volume resistivity tends to be low.

  As a board | substrate with a copper layer of this invention, a wiring board, an electrode board | substrate, a heat conductive path board, etc. are mentioned.

  EXAMPLES Hereinafter, although an Example is shown and demonstrated about this invention, this invention is not limited to these Examples at all.

<Example 1>
[1.1] Synthesis of copper nonanoate To 91.5 g (0.94 mol) of copper hydroxide (Kanto Chemical Co., Ltd., special grade), 150 mL of 1-propanol (Kanto Chemical Co., Ltd., special grade) was added and stirred. 370.9 g (2.34 mol) of nonanoic acid (Kanto Chemical Co., Inc., 90% by mass or more) was added. The obtained mixture was heated and stirred at 90 ° C. for 30 minutes in a separable flask. The obtained solution was filtered while heated to remove undissolved substances. Thereafter, the mixture was allowed to cool, and the produced copper nonanoate was suction filtered and washed with hexane until the washing liquid became transparent. The obtained powder was dried in an explosion-proof oven at 50 ° C. for 3 hours to obtain copper (II) nonanoate. The yield was 340 g (yield 96 mass%).

[1.2] Synthesis of copper particles 21.01 g (0.056 mol) of nonanoate copper (II) obtained above and copper (II) acetate anhydride (Kanto Chemical Co., Ltd., special grade) 4.33 g (0.3. 024 mol) is placed in a separable flask, 10 mL of 1-propanol and 32.1 g (0.32 mol) of hexylamine (Tokyo Chemical Industry Co., Ltd., purity 99 mass%) are added, and the mixture is heated and stirred at 80 ° C. in an oil bath. And dissolved. After transferring to an ice bath and cooling to an internal temperature of 5 ° C., a solution obtained by dissolving 7.72 mL (0.16 mol) of hydrazine monohydrate (Kanto Chemical Co., Ltd., special grade) in 12 mL of 1-propanol Added to the copper solution and stirred in an ice bath. The molar ratio of copper: hexylamine is 1: 4. Subsequently, it heated and stirred at 90 degreeC in the oil bath. At that time, the reduction reaction accompanied with foaming progressed, and the reaction was completed within 10 minutes. The inner wall of the separable flask had a copper luster and the solution turned dark red. Centrifugation was performed at 4000 rpm (rotation / min) for 1 minute to obtain a solid. The step of further washing the solid with 15 mL of hexane was repeated three times to remove the acid residue, thereby obtaining a copper cake containing copper particles having copper luster.

[1.3] Preparation of conductive material Obtained copper cake (60 parts by mass), terpineol (20 parts by mass), and isobornylcyclohexanol (trade name: Tersolve MTPH, Nippon Terpene Chemical Co., Ltd.) (20 parts by mass) ) To prepare a conductive material.

[1.4] Conductivity In an atmosphere in which the above conductive material is coated on a polyethylene naphthalate (PEN) film and the oxygen concentration in argon is 100 ppm and the formic acid concentration is 5% by volume, the heating rate is 15 ° C. / Heated to 120 ° C. for 60 minutes and held for 60 minutes to form a copper film.

[Evaluation of low-temperature conductor]
The volume resistivity was calculated from the surface resistance value and the film thickness of the obtained copper film. The film thickness of the copper film was measured with a non-contact surface / layer cross-sectional shape measurement system (VertScan, Ryoka System Co., Ltd.).
Based on the above results, when the volume resistivity is 300 μΩcm or less, the low-temperature conductorization is “good”, and when it exceeds 300 μΩcm, the low-temperature conductorization is evaluated as “bad”.

  The result was 30 μΩcm, and a conductor having a sufficiently low volume resistivity was formed. As mentioned above, it turned out that the copper containing particle | grains of this invention can be conductorized at low temperature.

[Measurement of content of organic substance having amino group in copper-containing particles]
After drying the copper cake and removing hexane in the copper cake, it is heated at a temperature equal to or higher than the temperature at which the organic matter is thermally decomposed, and by comparing the mass before and after the heating, the organic substance having an amino group in the copper-containing particles When the content rate was measured, it was 3.5 mass%.

<Example 2>
Copper-containing particles were synthesized and made conductive in the same manner as in Example 1 except that the oxygen concentration was 1000 ppm. The result was 210 μΩcm, and a conductor having a sufficiently low volume resistivity was formed.

<Example 3>
Copper-containing particles were synthesized and made conductive in the same manner as in Example 1 except that the oxygen concentration was 500 ppm. The result was 220 μΩcm, and a conductor having a sufficiently low volume resistivity was formed.

<Comparative Example 1>
Copper-containing particles were synthesized and converted into conductors in the same manner as in Example 1 except that the oxygen concentration was 100,000 ppm. As a result, no continuity was obtained.

Claims (6)

A conductive material including a copper-containing core particle containing copper and an organic substance having an amino group disposed on at least a part of the surface of the core particle and a conductive material including a dispersion medium is applied to the conductive material. Forming a content layer;
Forming a copper layer by heat-treating the conductive material-containing layer in a temperature range of 150 ° C. or lower in an atmosphere containing an acid that can be introduced as a saturated gas and having an oxygen concentration of 1 ppm to 10,000 ppm;
The manufacturing method of the board | substrate with a copper layer containing this.   The manufacturing method of the board | substrate with a copper layer of Claim 1 whose content rate of the organic substance which has an amino group in the said copper containing particle | grain is 0.1 mass%-20 mass%.   The manufacturing method of the board | substrate with a copper layer of Claim 1 or Claim 2 with which the organic substance which has the said amino group has a C7 or less alkyl group.   The manufacturing method of the board | substrate with a copper layer of any one of Claims 1-3 whose content rate of the copper oxide in the said core particle is 5 mass% or less.   The board | substrate with a copper layer obtained by the manufacturing method of any one of Claims 1-4. A substrate,
A sintered material of a conductive material containing copper-containing particles and a dispersion medium having copper-containing core particles and an amino group-containing organic substance arranged on at least part of the surface of the core particles, which are disposed on the substrate A copper layer,
A substrate with a copper layer.