WO2013115300A1

WO2013115300A1 - Method for inducing conductivity in films including metal microparticles

Info

Publication number: WO2013115300A1
Application number: PCT/JP2013/052151
Authority: WO
Inventors: 正人栗原; 時任　静士; 大介熊木
Original assignee: 国立大学法人山形大学
Priority date: 2012-02-03
Filing date: 2013-01-31
Publication date: 2013-08-08
Also published as: JP2013161593A

Abstract

The purpose of the present invention is to provide a means with which the sintering temperature and time required to induce conductivity in a variety of metal microparticles can be reduced. This method for inducing conductivity includes a step in which a gas having a water-vapour content of at least 14g/m³ is brought into contact with at least one section of a film including coated metal microparticles which have been provided on a substrate and coated with a protective film including alkylamine.

Description

Method for converting a film containing fine metal particles into a conductor

The present invention relates to a method for forming a conductive film containing metal fine particles and a method for forming a conductive film on a substrate using the method.

In recent years, with the reduction in size and weight of many electronic devices, various ingenuity and improvements have been made for printed wiring boards. For example, not only polyimide that is already used as a flexible printed circuit board, but also fine electronic materials for various organic polymer substrates that are easier to process, such as PET (polyethylene terephthalate) and polypropylene, which have lower heat resistance than polyimide. There is a need for a technique that enables circuit formation. In other words, it is difficult to apply a method of forming a circuit by various etchings by providing a metal layer by sputtering or plating, which has been conventionally used, and it is difficult to apply a low temperature to the organic polymer substrate. There is a need for a technique that enables the formation of a metal film that easily forms a fine electronic circuit in the environment. In addition, the conventional method for forming a metal layer on the surface of a resin or the like is limited to sputtering that requires a vacuum environment or plating using a toxic chemical, and the metal layer is easily formed on the surface of the substrate. Was difficult.

In contrast, by applying ink containing nanometer-sized metal fine particles to the substrate surface and sintering the metal fine particles at a relatively low temperature, a metal layer can be easily provided on the substrate surface. It's getting on. By applying this technology, as a means of forming a fine electronic circuit on an organic polymer substrate or the like, a circuit is drawn on the substrate by various printing methods using ink containing nanometer-sized metal fine particles, Thereafter, it is expected to form an electronic circuit by exhibiting electrical conductivity by sintering metal fine particles at a low temperature.

As an ink containing such metal fine particles, for example, as an ink containing nanometer-sized coated metal fine particles that are excellent in dispersibility in a dispersion medium and exhibit good conductivity by low-temperature sintering on a flexible printed circuit board, A metal ink in which colloidal silver is dispersed in a dispersion medium composed of alcohol and various alcohols (see, for example, Patent Document 1) or a combination of a plurality of alkylamines and deposited on silver oxalate or the like to form a complex compound. There has been reported an ink in which coated silver ultrafine particles having a uniform particle diameter obtained by heating and pyrolyzing the complex compound are dispersed in an appropriate dispersion medium (see, for example, Patent Document 2).

The reason why the silver fine particles described in Patent Documents 1 and 2 are sintered at a temperature much lower than the melting point of silver to form a metal film is because such silver fine particles have a very large specific surface area. Therefore, it is considered that a force to reduce the surface area works due to the surface tension. For this reason, when performing low temperature sintering, it is necessary to give a large specific surface area by reducing the average particle diameter of the silver fine particles as much as possible. However, when trying to produce silver fine particles having a small average particle diameter, the particles are agglomerated (sintered) by the surface tension of the silver fine particles in the production process, resulting in coarse particles that do not cause further low-temperature sintering. The problem arises that only particles can be obtained.

In order to eliminate such problems and stably produce fine silver fine particles, and to improve the storage stability of the produced silver fine particles, the silver fine particles described in Patent Document 2 have an alkylamine on the surface of the silver fine particles. By providing a film containing molecules and optimizing the type of the alkylamine, it can be sintered at room temperature, which is extremely low as the sintering temperature of silver, and is stable at a high concentration in an organic solvent. There has been proposed a method for producing coated silver fine particles that can be dispersed in a wide range and is very useful in various applications.

On the other hand, as a means for sintering the produced metal nanoparticles at a lower temperature, a metal nanoparticle paste containing the coated metal nanoparticles and a dispersion solvent is applied on a substrate, and a polar solvent or a dissolution aid is applied. There has also been proposed a method for sintering coated metal fine particles having excellent storage stability, which can be carried out regardless of temperature by allowing a polar solvent solution to be contained (see Patent Document 3). Self-assembled silver nanoparticles have also been reported that can be sintered at room temperature by exposing silver nanoparticles stabilized with sodium salt of polyacrylic acid to hydrogen chloride (HCl) gas for a short time ( For example, refer nonpatent literature 1).

Japanese Patent Laid-Open No. 2008-214591 JP 2010-265543 A Japanese Patent No. 2008-72052

The silver nanoparticles described in Non-Patent Document 1 are designed so that they can be sintered at room temperature, but there remains a problem in terms of using a corrosive / acid gas called hydrogen chloride (HCl) gas. . Although the method described in Patent Document 3 can surely be sintered at room temperature, it requires a step of immersing the substrate in a polar solvent solution, and the disposal of the polar solvent used in these treatments is also necessary. There is a problem that it is necessary. On the other hand, the method described in Patent Document 2 proposes a new possibility for low-temperature sintering of metal fine particles, but the low-temperature sinterability depends on the characteristics of the metal fine particles themselves, A method for reducing the temperature of the conductor treatment by improving the process is not disclosed. Accordingly, an object of the present invention is to provide means for reducing the sintering temperature for various metal fine particles and reducing the time.

In order to solve the above-mentioned problems, the present inventors have intensively studied a method for making metal fine particles into a conductor. As a result, when the coated metal fine particles coated with a protective film containing an alkylamine are made conductive on the substrate, It was found that the subsequent conductorization is promoted by bringing the film containing the coated metal fine particles provided in the plate into contact with a gas containing a certain amount of water vapor.

That is, in the first aspect of the present invention, a method for converting a film containing coated metal fine particles, which is provided on a substrate and covered with a protective film containing alkylamine, into a conductor is at least part of the film. It includes a step of contacting a gas containing water vapor of 14 g / m ³ or more.

In one embodiment of the present invention, in at least a part of the step of contacting a gas containing said 14 g / m ³ or more steam, contacting a gas containing 20 g / m ³ or more steam to the film It is characterized by making it.

In one preferred embodiment of the present invention, the step of bringing at least a part of the film into contact with a gas containing water vapor of 14 g / m ³ or more is performed by a protective film including an alkylamine provided on the substrate. It is characterized in that it is carried out in almost the whole method for converting a film containing coated fine metal particles into a conductor.

In a further preferred embodiment of the present invention, the coated metal fine particles coated with the protective film containing an alkylamine are produced by thermally decomposing a complex compound containing a metal compound in the presence of an alkylamine. It is characterized by.

In the different viewpoint of this invention, the base | substrate which has a conductor film obtained by implementing said conductorization method is provided.
Therefore, in a specific embodiment of the present invention, (a) forming a film containing coated metal fine particles coated with a protective film containing alkylamine on a substrate, and (b) including the coated metal fine particles. There is provided a method for making a film including a coated metal fine particle comprising a step of bringing at least a part of the film into contact with a gas containing 14 g / m ³ or more of water vapor. It is preferable that at least a part of the step (b) or in addition to the step (b) includes a step of maintaining the film containing the coated metal fine particles at a predetermined temperature. The predetermined temperature is more preferably 40 ° C. to 100 ° C.

According to the present invention, in a method for forming a film containing coated metal fine particles, exposure to a gas phase having a predetermined moisture content makes it possible to exhibit high conductivity at a lower temperature and in a shorter time. This is useful in forming a metal film using fine particles. That is, it is possible to form a substantially conductive metal film even at a temperature close to room temperature of about 40 ° C., for example, various printed wirings using a substrate having low heat resistance without being limited to a material such as a wiring substrate. It contributes to offer.

Volume resistivity in the process of conducting the substrate coated with the dispersion 1 produced in Preparation Example 1 in a constant temperature and humidity chamber at 40 ° C. under different humidity conditions of 38%, 60% or 80% relative humidity. It is the result of plotting. Process for converting the substrate coated with the dispersion 1 produced in Preparation Example 1 into a conductor in a constant temperature and humidity chamber at 50 ° C. under different humidity conditions of 35%, 50%, 60%, 70% or 80% relative humidity. It is the result of having plotted the volume resistivity in. The volume resistivity in the process of conducting the substrate coated with the dispersion 1 produced in Preparation Example 1 in a constant temperature and humidity chamber at 70 ° C. under different humidity conditions of 30%, 40% or 50% relative humidity. It is the result of plotting. Results of plotting the volume resistivity in the process of conducting the substrate coated with the dispersion 1 produced in Preparation Example 1 in a constant temperature and humidity chamber with a relative humidity of 50% under different temperature conditions of 60 ° C. and 80 ° C. It is. 4 is a cross-sectional image (FE-SEM) of a film after the dispersion 1 produced in Preparation Example 1 is applied on a silicon substrate and made conductive under the conditions of Example 12. FIG. 2 is an example of a metal fine particle (transmission image (STEM image) observed using a thermal field emission scanning electron microscope (JEOL JSM-7600F)) whose conduction is promoted by the present invention.

Hereinafter, the present invention will be described in detail.

(Metal fine particles used in the present invention)
The coated metal fine particles to be converted into a conductor by the method of the present invention are typically those in which the surface of metal fine particles having a particle diameter of about several nm to 40 nm is coated with a protective film containing alkylamine. The metal constituting the metal fine particles is selected depending on the use of the present invention, and for example, a metal such as silver, copper, gold, platinum, rhodium, nickel, palladium, or an alloy thereof is used. These two or more metals may be metal fine particles having a core-shell structure or the like.

FIG. 6 shows an example of coated metal fine particles that can be easily converted into a conductor by the method of the present invention. FIG. 6 shows silver fine particles coated with a protective film containing an alkylamine produced by the method described in Patent Document 2. In the coated silver fine particles, the particle diameter of the silver fine particles is about 5 to 20 nm, and the surface thereof is covered with a protective film containing an alkylamine having a thickness of about several nm. The fine particles can exist independently and stably.

On the other hand, when the coated silver fine particles are heated to an appropriate temperature, the alkylamine forming the protective film is detached and the silver fine particles are brought into direct contact with each other, thereby forming a conductor. It has been confirmed that silver atoms constituting the fine particles are diffused and fused with each other, and the formation of a conductor progresses (Patent Document 2). This phenomenon is because the alkylamine forming the protective film is weakly bonded to the surface of the silver fine particles by the coordination bond via the amino group, and the alkylamine can be removed relatively easily. It is considered.

In the process of applying a coated metal fine particle whose surface is coated with a protective film containing an alkylamine as shown in FIG. 6 on a substrate in the form of ink or paste, a predetermined amount of the metal fine particle is applied. By including a step of contacting with a gas containing water vapor, further desorption of alkylamine and contact / sintering of metal fine particles can be further promoted to lower the temperature required for conductorization and for a short time. This relates to a technique for producing a conductor.

1 Step of Conducting a Film Containing Coated Metal Fine Particles in the Presence of Water Vapor The coated metal fine particles made conductive by the method of the present invention typically have a surface of metal fine particles having a particle size of about several nm to 40 nm. May be coated with a protective film containing an alkylamine, and the present invention can be applied to coated metal fine particles produced by various methods. For example, as described in Patent Document 2, alkylamine-coated silver fine particles obtained by thermally decomposing a complex of a silver compound and an alkylamine may be used, and metal atoms may be aggregated in a gas phase. A protective film containing an alkylamine may be provided on the metal fine particles formed in this manner. Further, the metal fine particles formed in the liquid phase, the surface of which is protected with an appropriate protective film, the protective film is replaced with a protective film containing alkylamine by appropriate means. Also good.

Alkylamine molecules contained in the protective film covering the coated metal fine particles generally have a coordination bond with the surface of the metal fine particles, and the amino group is stabilized as a protective film by the cohesive force between the alkylamine molecules. It is thought to do. The coated metal fine particles coated with a protective film containing an alkylamine to which the present invention is applied are generally designed so that the protective film exists stably when coexisting with a desired organic solvent used as a dispersion medium. It is desirable. On the other hand, for example, after the organic solvent or the like is applied to the substrate and evaporated to be removed, the alkylamine contained in the protective film is easily released, and the alkylamine starts to be released at an appropriate temperature. It is desirable to be designed as follows. The stability of the alkylamine contained in the protective film and the ease of desorption can be mainly determined by the molecular weight and molecular structure of the alkylamine contained in the protective film, as described in Patent Document 2, for example. .

According to the present invention, a gas containing a predetermined amount of water vapor is applied in the process of applying a coated metal fine particle whose surface is coated with a protective film containing an alkylamine on a substrate in the form of an ink or a paste. By making it contact, compared with the case where it does not contact the gas containing the said water vapor | steam, the temperature for producing conductorization can be made low temperature, and progress of conductorization can be accelerated | stimulated. Although it is not always clear why a film containing coated metal fine particles is made conductive at a lower temperature by contacting a gas phase containing a predetermined amount of water vapor, the gas containing the predetermined amount of water vapor contains coated metal fine particles. It is thought that by bringing the membrane into contact, water molecules are adsorbed or taken into the protective film of the coated metal fine particles, thereby promoting desorption of alkylamine molecules. For this reason, in the coated metal fine particles to be conductorized according to the present invention, it is desirable that alkylamine is a main component in the protective film. It is presumed that conductorization can be effectively performed by such a conductorization method.
The term “conducting” in the present invention means that the electrical resistance of the film containing the coated metal fine particles which are substantially non-conductive is lowered to about 1 Ωcm or less to produce electrical conductivity, and once occurs. Including improving electrical conductivity.

Here, “contact with a gas containing water vapor” means that a gas (gas) containing water vapor is present in the vicinity of the surface of the substrate on which the coated metal fine particles are applied. Including forced contact with water molecules contained therein. Alternatively, the substrate may be held in a predetermined humidity environment (either atmospheric pressure or pressurized), and the coated metal fine particles may be brought into contact with water vapor. The temperature at which the gas containing the predetermined amount of water vapor is brought into contact with the film containing the coated metal fine particles is, for example, sufficiently low and substantially during the contact with the gas containing the predetermined amount of water. It may be a temperature that does not cause conductive formation on the other hand, while it may be a temperature that causes substantial conduction while being in contact with a gas containing a predetermined amount of moisture at a relatively high temperature. . Further, it may be a process in which the film containing the coated metal fine particles is heated to change its temperature.

In other words, in the process of making a conductor spontaneously by exposing a film containing coated metal fine particles to a relatively high temperature, a gas containing a predetermined amount of water vapor is brought into contact with the surface of the film containing coated metal fine particles to be made conductive. Also, it is possible to promote the formation of a conductor. In addition, as a pre-process of the step of conducting, a process of making a conductor by heating after contacting a gas containing a predetermined amount of water vapor at a relatively low temperature on the surface of the film containing the coated metal fine particles to be made conductive May be performed. Furthermore, a gas containing a predetermined amount of water vapor may be contacted as part of the step of conducting the conductor by applying a predetermined temperature history to the surface of the substrate provided with the coated metal fine particles to be made conductive.

In particular, when a film containing coated metal fine particles mainly composed of a metal such as silver that does not oxidize is made into a conductor, the coated metal fine particles are continuously made conductive in the process until desired conductivity is produced. It is preferable that a gas containing a predetermined amount of moisture is brought into contact with the surface of the film containing. On the other hand, when making a film containing coated metal fine particles containing a metal that oxidizes a problem into a conductor, in a part of the process of making a conductor, a predetermined amount is applied to the surface of the film containing coated metal fine particles to be made conductive. It is preferable that the metal fine particles are not brought into contact with excessive moisture by contacting a gas containing water vapor.

As the amount of moisture contained in the gas in contact with the film containing the coated fine metal particles increases, conductorization is more likely to progress, and there is a tendency to show high conductivity when conducting the conductorization treatment for a certain period of time. By increasing the amount of water molecules supplied to the surface of the film containing the coated fine metal particles, it is possible to further promote the formation of a conductor.
The specific degree of conductorization varies depending on the amount of moisture contained in the gas, the time for which the gas is brought into contact with the coated metal fine particles, and the temperature at which the conductor is made, but particularly in the temperature range of 100 ° C. or less. It is observed that the volume resistivity after conducting the conductor for a predetermined time due to the increase in the amount of water contained is significantly reduced. For example, in the case of using coated silver fine particles capable of obtaining a volume resistivity of about several μΩcm in a state where the conductorization is almost completely completed, the volume absolute humidity (water vapor amount) is 14 to 17 g / m. ^By installing in a gas containing about ³ water vapor, dew condensation does not occur even around normal room temperature, but substantial conductorization is possible by taking time. Further, even at an extremely low temperature of about 40 ° C., a volume resistance of 1 mΩcm or less is obtained in about 60 minutes, and substantial conduction can be obtained. On the other hand, when the amount of water vapor is less than 14 g / m ³ , particularly when the water vapor amount is 10 g / m ³ or less, the promotion of conductorization by water vapor is substantially not observed.

In addition, when installed in a gas containing water vapor of 20 to 25 g / m ³ or more, a volume resistivity of 100 μΩcm or less is obtained in a time of about 60 minutes without causing condensation even at an extremely low temperature of about 40 ° C. A good electric circuit can be formed even on a substrate that is difficult to heat. Furthermore, by setting the amount of water vapor to 30 to 35 g / m ³ or more, the volume resistivity can be stably reduced even in a conductor at an extremely low temperature of about 40 ° C. Furthermore, when conducting the conductor at a temperature of about 50 ° C., it becomes possible to use a gas containing water vapor of 40 to 45 g / m ³ or more without causing dew condensation. Volume resistivity can be obtained. Furthermore, at 50 ° C., no condensation occurs even when a gas containing 50 to 55 g / m ³ or more of water vapor or a gas containing 60 to 65 g / m ³ or more of water vapor is used. A volume resistivity of 20 μΩcm or less can be obtained, and sufficient conductivity can be imparted in a short time in electrical circuit applications. Further, the amount of water vapor contained in the gas may be appropriately changed in the process of performing treatment with the gas containing water vapor.

The reason why the volume resistivity can be reduced by making a gas containing a predetermined amount of water vapor in contact with a film containing coated metal fine particles in the process of forming a conductor is that water molecules in the gas are adsorbed and taken into the film. As a result, the elimination of the electrically insulating alkylamine contained in the protective film of the coated metal fine particles is promoted. As a result, the metal fine particles are brought into direct contact with each other to cause conduction, and diffusion of metal atoms in the contacted portion. This is considered to be because the contact area is increased due to, and fusion (sintering) occurs. And it is guessed that the role of the gas containing water vapor in the present invention is to supply water molecules to the film containing the coated metal fine particles.

In the above description, the relationship between the amount of water vapor contained in the gas used and the volume resistivity after the formation of the conductor has been described by taking as an example the formation of a film containing coated silver fine particles. In the case of fine particles, by applying the present invention, elimination of alkylamine is promoted, and it is possible to promote the formation of a conductor. Needless to say, the volume resistivity of the film obtained by making the conductor varies depending on the composition of the metal constituting the metal fine particles used.
In the gas containing water vapor, gas components other than water vapor are not particularly specified, and can be determined according to the ease of treatment and the type of metal constituting the coated metal fine particles to be treated. That is, in the case of coated silver fine particles or the like where oxidation does not become a problem, the treatment can be performed using air appropriately humidified or the like. On the other hand, when a metal such as coated copper fine particles that easily oxidizes is included, it is preferable to use a predetermined amount of water vapor mixed with an inert gas such as argon or nitrogen. It is also possible to use a gas that does not substantially contain a gas other than water vapor. In addition, it is also possible to use a gas to which an appropriate gas component is added as long as it does not contradict the spirit of the present invention.

In the process of treatment with a gas containing water vapor, it is usually convenient to set the total pressure of the gas to atmospheric pressure. However, the present invention is not limited to this, and a film or gas containing coated fine metal particles to be treated is necessary. The treatment can be performed under reduced pressure or increased pressure as appropriate. Moreover, you may change suitably the pressure of the gas used for a process in the process in which a process is performed. The temperature and time for conducting the film containing the coated fine metal particles are not particularly limited, and are mainly determined according to various characteristics such as conductivity required for the film made into a conductor. There is a tendency for the conductivity to improve because the temperature is high and the residual ratio of the protective film of the coated metal fine particles decreases due to the formation of a conductor for a long time, and the fusion between the metal fine particles proceeds. In particular, when the coated metal silver fine particles produced by the metal amine complex decomposition method used in the following examples are used, a volume resistance value of 100 μΩcm is obtained at a temperature of 50 ° C. in about 5 minutes from the start of the treatment. After 60 minutes, a volume resistance value of 20 μΩcm is obtained. At 80 ° C., a volume resistance value of 30 μΩcm can be obtained in about 2 minutes from the start of the treatment, and a volume resistance value of 15 μΩcm can be obtained after 10 minutes. On the other hand, when conductorization is performed at an excessively high temperature, there is a risk of excessive crystal grain growth due to diffusion of metal atoms.

In the method of the present invention, the term “relative humidity” is a value expressed as a percentage by dividing the pressure of water vapor (water vapor partial pressure) contained in the atmosphere at a certain temperature by the saturated water vapor pressure at that temperature, It can be expressed by the following formula.
RH = Ep / E × 100 (%)
RH: Relative humidity in mixed air of water vapor and air Ep: Water vapor pressure in mixed air E: Saturated water vapor pressure of mixed air at the temperature

The term “volumetric absolute humidity” refers to the amount of water vapor contained in the unit volume of the atmosphere expressed by weight (unit: g / m ³ ). It can be expressed by the following formula.
Volumetric absolute humidity = 216.7 x Ep / T
T is the temperature (K) (T = t [° C.] + 273.15).

Such a humidity environment may be a local atmospheric environment that comes into contact with at least the coated metal fine particles on the surface of the substrate, but in general, a certain sealed space is set to reduce the humidity in the space. The adjustment method is simple.

In the above, by conducting the process of converting the film containing the coated metal fine particles mainly on the substrate into a conductor by treating the film at a predetermined temperature for a predetermined time in a gas containing a predetermined amount of water vapor, the conductor of the film We explained about promoting
On the other hand, the temperature at which the film containing the coated metal fine particles is treated with the gas containing water vapor may be sufficiently low. That is, for example, after performing a step of exposing a film containing coated metal fine particles to a predetermined humidity environment in a temperature range where substantial conductorization does not progress, the film containing coated metal fine particles is heated to a predetermined temperature. Thus, the process of making a conductor can be performed. At this time, the temperature of the film containing the coated metal fine particles can be continuously changed. Further, by supplying a gas having a predetermined temperature and humidity to the film containing the coated metal fine particles, it is possible to simultaneously supply and heat water vapor to the film containing the coated metal fine particles. Furthermore, it is also possible to expose to a predetermined humidity environment in part of the process of making the film containing the coated metal fine particles substantially conductive.

In the present invention, the term “sintering” refers to a phenomenon in which metal fine particles are fused to form a bond. In addition, “conducting” is manifested when metal fine particles come into contact with each other inside a film containing coated metal fine particles to form a conductive path, and further, the metal fine particles are sintered together to expand the conductive path. It means that the volume resistivity decreases. In addition, a film that has conductivity due to the formation of a conductive path by contacting the metal fine particles inside the film containing the coated metal fine particles may be particularly referred to as a “conductor film”. However, in the process of making a conductor, a film containing coated metal fine particles may correspond to a “conductor film”.

In addition, the method for making a film containing coated metal fine particles according to the present invention can be widely used as a means for forming a metal layer on a substrate surface, as well as a means for forming an electric circuit on the substrate surface. Needless to say, it can be widely used as a forming means, a plating means, a decoration means, and the like.

In the following description, as an example of a method for producing coated metal fine particles to be converted into a conductor by applying the present invention, means for producing coated metal fine particles by a metal amine complex decomposition method will be described. Without being limited to the above, the present invention can be applied to various coated metal fine particles whose surface is coated with a protective film containing an alkylamine. In the coated metal fine particles produced by the metal amine complex decomposition method, generally, there is no oxide layer on the surface of the metal fine particles, and the amino group of the alkylamine molecule is bonded to the surface of the metal fine particles in the metal state by a coordinate bond. In order to form a protective film, it is easy to desorb alkylamine molecules, and the surface of the metal fine particles after desorption of alkylamine molecules is likely to cause fusion due to diffusion of metal atoms. Preferred as coated metal fine particles.

2. Method for producing coated metal fine particles by metal amine complex decomposition method As a metal raw material used for producing coated metal fine particles, a metal that is easily decomposed by heating in a compound containing the metal to generate an atomic metal Compounds are preferably used. Examples of such metal compounds include metal carboxylates such as formic acid, acetic acid, oxalic acid, malonic acid, benzoic acid, phthalic acid and metal carboxylates, metal chlorides, nitrates, carbonates, and the like. Can be mentioned. In particular, examples of the silver compound used as a raw material for the coated silver fine particles shown in the following examples include silver chloride, silver nitrate, silver carbonate, and the like, in addition to silver carboxylate in which carboxylic acid and silver are combined. Among these, silver oxalate is preferably used from the viewpoints of easily producing metallic silver by decomposition and hardly generating impurities other than silver.

In the metal amine complex decomposition method, a metal compound and an appropriate alkyl amine are mixed and heated to produce a complex compound composed of the metal compound and the alkyl amine, and then an alkyl amine or the like is present. Producing metal fine particles coated with a protective film containing alkylamine by heating the complex compound in the environment, thermally decomposing the metal compound contained in the complex compound, and aggregating the generated atomic metal Can do. Alternatively, the coated metal fine particles may be produced by forming a complex compound of a compound containing an amino group other than alkylamine and a metal compound, and heating the complex compound in an environment where alkylamine or the like is present.

Alkylamine molecules and the like are coordinated to the metal atoms generated in the process of decomposing such metalamine complexes, and the movement of the metal atoms during aggregation is controlled by the action of the alkylamine molecules. Presumed to be. As a result, it is possible to produce metal fine particles that are very fine and have a narrow particle size distribution. In addition, many alkylamine molecules also form a relatively weak coordination bond on the surface of the generated metal fine particles, and these form a dense protective film on the surface of the metal fine particles, so they have excellent storage stability. It is possible to produce coated fine metal particles. In addition, since the alkylamine molecules forming the film can be easily detached by heating or the like, it is possible to produce metal fine particles that can be sintered at a very low temperature.
In addition, in order to add various components to the protective film on the surface of the coated metal fine particles produced by the metal amine complex decomposition method for the purpose of adding various functions, etc., the reaction medium for thermal decomposition of the complex compound By the presence of the component, the component can be added to the protective film of the generated coated metal fine particles.

Alkylamine that can be used in the metal amine complex decomposition method is capable of forming a coordinate bond via an amino group to the metal atom in the metal compound and the surface of the metal fine particles generated by the metal amine complex decomposition method. In addition, an alkyl group RNH ₂ (R is a hydrocarbon chain) in which the amino group contained in the amine moiety is a primary amino group or an alkylamine R ¹ R ² NH (R ¹ and R ² are hydrocarbons) that is a secondary amino group The chains may be the same or different). By including a primary or secondary amino group, a complex bond between the amine moiety and the metal compound can be formed by generating a coordinate bond to the metal atom by the unshared electron pair of the nitrogen atom in the amino group, Thereby, an alkylamine film can be formed on the metal fine particles. On the other hand, when a tertiary amino group is included, the free space around the nitrogen atom in the amino group is generally narrow, which is undesirable in that a coordination bond to a metal atom is difficult to occur.

In alkylamines and the like, generally, as the molecular weight of the alkyl group increases and the chain becomes longer, the vapor pressure decreases and the boiling point tends to increase. On the other hand, when the alkyl group has a small molecular weight and a short chain, the vapor pressure is high and the polarity tends to be strong. In addition, alkyldiamines having two amino groups in one molecule tend to be more polar than alkylmonoamines having one amino group in one molecule. The alkylamines used in the metal amine complex decomposition method focus on such a tendency, and in particular, classify them based on the molecular weight and the number of amino groups such as alkylamines, and mix multiple types of alkylamines according to the purpose. And preferably used as an alkylamine mixture. In the present specification, those having 2 to 5 carbon atoms contained in an alkyl group such as alkylamine are short chain, those having 6 to 12 carbon atoms are medium chains, and those having 13 or more carbon atoms are long chains. They are defined and distinguished from each other.

In the metal amine complex decomposition method, mainly from the viewpoint of forming a good coating film on the metal fine particles produced, the amine mixture used is one amino group for the long chain and / or medium chain alkyl group. Those containing a long-chain / medium-chain alkyl monoamine formed by bonding groups are preferably used. Long chain and medium chain alkyl monoamines generally have a low vapor pressure and are unlikely to evaporate, and have high affinity with organic solvents. Therefore, coated metal fine particles are produced by using an amine mixture containing these components. This coating also contains long-chain / medium-chain alkyl monoamines at a predetermined ratio, so that the storage stability can be improved and the dispersibility in a nonpolar organic solvent can be improved.

Examples of such long and medium chain alkyl monoamines include dipropylamine (107 ° C), dibutylamine (159 ° C), hexylamine (131 ° C), cyclohexylamine (134 ° C), heptylamine (155 ° C). ), 3-butoxypropylamine (170 ° C), octylamine (176 ° C), nonylamine (201 ° C), decylamine (217 ° C), 3-aminopropyltriethoxysilane (217 ° C), dodecylamine (248 ° C), Alkylmonoamines such as hexadecylamine (330 ° C), oleylamine (349 ° C), octadecylamine (232 ° C (at 32 mmHg)) are practical in terms of easy availability, but are not limited thereto. If it is a long chain or medium chain alkyl monoamine having 6 or more carbon atoms, Flip and can be used.

In general, when an alkylamine having a relatively low molecular weight is used in the range of the medium-chain alkyl monoamine, the vapor pressure of the protective film is high and the film is easily removed, so that it tends to be sintered at a lower temperature. There is a tendency for storage stability to decrease. Moreover, the tendency for the affinity with an organic solvent to fall and the ratio dispersible in a predetermined organic solvent falls. On the other hand, the use of an alkyl monoamine having a relatively large molecular weight tends to provide coated metal fine particles having a strong protective film. Moreover, since the dispersibility in a nonpolar solvent becomes high, it is advantageous when used as an ink by being dispersed in an organic solvent at a high ratio.

In addition, as described above, in the present invention, a short-chain alkyl monoamine can be contained in the amine mixture in a predetermined ratio with respect to the long-chain / medium-chain alkyl monoamine. In general, as the alkyl chain of the alkyl monoamine becomes longer, the rate of forming a complex compound with the metal compound tends to decrease. When a long-chain alkyl monoamine having about 18 carbon atoms is used, It is also observed that the formation of complex compounds is not completed by prolonged mixing. In contrast, when a short-chain alkyl monoamine having 5 or less carbon atoms is mixed with a long-chain / medium-chain alkyl monoamine at a predetermined ratio, the time required for forming a complex compound is shortened, Even when a chain alkyl monoamine is used, a complex compound can be satisfactorily formed.

In addition, the complex compound formed in the presence of the short-chain alkyl monoamine tends to cause decomposition of the metal compound contained in the complex compound at a lower temperature in the subsequent thermal decomposition step. Furthermore, in the coated metal fine particles produced using an amine mixture containing a short-chain alkyl monoamine at a predetermined ratio, the temperature required for sintering generally tends to decrease.

The effect obtained by mixing the short-chain alkyl monoamine as described above into the amine mixture can be sufficiently obtained if the number of carbon atoms is 5 or less. By using monoamine, the production rate of the complex compound can be improved. On the other hand, alkyl monoamines having a small number of carbon atoms and a high vapor pressure tend to increase the amount of evaporation at the time of decomposition of the metal compound or to decrease the storage stability of the produced coated metal fine particles. For this reason, alkyl monoamines having about 3 to 4 carbon atoms are preferably used, and these can be mainly used as short-chain alkyl monoamines. Short chain alkyl monoamines can be used by mixing a plurality of types as required.

Examples of the short-chain alkyl monoamine include amylamine (boiling point 104 ° C.), 2-ethoxyethylamine (105 ° C.), 4-methoxybutylamine, diisopropylamine (84 ° C.) butylamine (78 ° C.), diethylamine (55 ° C.), propylamine (48 ° C.), isopropylamine (34 ° C.), ethylamine (17 ° C.), dimethylamine (7 ° C.) and the like are industrially available and are desirably used.

The content of the short-chain alkyl monoamine in the amine mixture varies depending on the type of alkyl amine used, but is generally 10 to 80 mol% with respect to the total alkyl amine, so that the complex of the alkyl amine and the metal compound is achieved. Formation of the compound can be facilitated. In particular, when the amount is 25 mol% or more, the complex compound can be produced sufficiently smoothly, and complex compounds using various long- and medium-chain alkylamines can be produced. On the other hand, if the content of the short-chain alkyl monoamine in the amine mixture is 65 mol% or more, the coated metal fine particles produced are unstable, and this is not desirable because long-term storage becomes difficult. Furthermore, when the content of the short-chain alkyl monoamine is 80 mol% or more, when metal fine particles are generated by thermal decomposition of the complex compound, the aggregation of metal atoms is not well controlled and coarse particles are generated. Produce. In general, when the content of the short-chain alkyl monoamine in the amine mixture is 30 to 60 mol%, the produced coated metal fine particles can be stably held for several months in an appropriate organic solvent. .

In addition, water and low-molecular-weight alcohols also have strong polarity, and the effect of promoting the formation of complex compounds is observed, but in addition to increasing the vapor pressure of the amine mixture, it also affects the characteristics and yield of the coated metal fine particles produced It is not preferred to mix an excess amount into the amine mixture because it will have an effect. In the metal amine complex decomposition method, for example, a fatty acid such as oleic acid may be mixed with the amine mixture as a dispersant for improving the dispersibility of the generated coated metal fine particles in the dispersion medium. In particular, it is effective to add an appropriate fatty acid when an amine mixture having a small average molecular weight of alkylamine is used, for example, by containing a large proportion of short-chain alkylamine. However, when an excessive amount of fatty acid is used, the desorption temperature of the protective film from the coated metal fine particles tends to increase, so that the amount added is 5 mol relative to the metal atoms contained in the reaction system. % Or less is desirable.

In another embodiment of the metal amine complex decomposition method, a metal compound that decomposes by heating to produce an atomic metal, an alkyl monoamine having a boiling point of 100 ° C. to 250 ° C., and an alkyl diamine having a boiling point of 100 ° C. to 250 ° C. To prepare a complex compound containing the metal compound and the alkyl monoamine and alkyl diamine, and then using the coated metal fine particles obtained by heating the complex compound to thermally decompose the metal compound. it can.

The alkyl monoamine is not particularly limited in its structure, but it reacts with a metal compound to form the complex compound, so that it is a primary amino group RNH ₂ (R is a hydrocarbon chain) or a secondary amino group. R ¹ R ² NH is desirable (R ¹ and R ² may be the same or different in the hydrocarbon chain). In addition, the alkyl monoamine has a boiling point of 100 ° C. or higher in consideration of the thermal decomposition temperature of the complex compound, and a boiling point of 250 ° C. or lower in consideration of the low-temperature sinterability of the obtained coated metal fine particles. It is considered that. For example, 2-ethoxyethylamine (105 ° C), dipropylamine (107 ° C), dibutylamine (159 ° C), hexylamine (131 ° C), cyclohexylamine (134 ° C), heptylamine (155 ° C), 3-butoxy Propylamine (170 ° C), octylamine (176 ° C), nonylamine (201 ° C), decylamine (217 ° C), 3-aminopropyltriethoxysilane (217 ° C), dodecylamine (248 ° C) and the like. It is not limited to these.

The alkyl diamine has a boiling point of 100 ° C. or higher in consideration of the thermal decomposition temperature of the complex compound, and has a boiling point of 250 ° C. or lower in consideration of the low-temperature sinterability of the obtained coated metal fine particles. It is considered. For example, ethylenediamine (118 ° C), N, N-dimethylethylenediamine (105 ° C), N, N'-dimethylethylenediamine (119 ° C), N, N-diethylethylenediamine (146 ° C), N, N'-diethylethylenediamine ( 153 ° C.), 1,3-propanediamine (140 ° C.), 2,2-dimethyl-1,3-propanediamine (153 ° C.), N, N-dimethyl-1,3-diaminopropane (136 ° C.), N , N′-dimethyl-1,3-diaminopropane (145 ° C.), N, N-diethyl-1,3-diaminopropane (171 ° C.), 1,4-diaminobutane (159 ° C.), 1,5-diamino -2-methylpentane (193 ° C), 1,6-diaminohexane (204 ° C), N, N'-dimethyl-1,6-diaminohexane (228 ° C) , 1,7-diaminoheptane (224 ° C.), 1,8-but-diamino octane (225 ° C.), and the like, but is not limited thereto.

In another embodiment of the metal amine complex decomposition method, the total amount of alkyl monoamine having 5 or less carbon atoms and alkyldiamine having a boiling point of 100 ° C. to 250 ° C. contained in the protective molecule of the coated metal fine particle is alkyl Examples thereof include coated metal fine particles that are at least 20 mol%, preferably at least 30 mol% of the total amount of amine.
The coated metal fine particles produced as described above can be stably dispersed at a high concentration in an appropriate organic solvent such as an alcohol solvent such as butanol, a nonpolar solvent such as octane, or a mixed solvent thereof. It can be used as an ink by being dispersed in an organic solvent according to the purpose. As the organic solvent to be used, an organic solvent that does not cause detachment of alkylamine or the like contained in the protective film of the coated metal fine particles and evaporates relatively quickly when the dispersion is applied is preferably used.

3. Substrate for forming a film containing coated fine metal particles, and method for forming the film
In the method of the present invention, the material and shape of the substrate to which the ink or paste containing the coated metal fine particles is applied are not particularly limited, but for example, from thermoplastic resin, thermosetting resin, glass, paper, metal, silicon, ceramics, etc. Can be used. Examples of the thermoplastic resin include polyethylene, polyethylene terephthalate, polypropylene, polyvinyl chloride, polystyrene, acrylonitrile-butadiene-styrene copolymer resin, acrylonitrile-styrene copolymer resin, polycarbonate, polyacetal, polybutylene terephthalate, polyphenylene oxide, polyamide, Polyphenylene sulfide, polysulfone, polyethersulfone, polyether-etherketone, polyarylate, aromatic polyester, aromatic polyamide, fluororesin, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetate, polyvinyl formal, polyvinyl butyral, polymethyl methacrylate And cellulose acetate.

Examples of the thermosetting resin include phenol resin, urea resin, xylene resin, urea resin, melamine resin, epoxy resin, silicon resin, diallyl phthalate resin, furan resin, aniline resin, acetone-formaldehyde resin, alkyd resin, and the like. Can be mentioned. The ceramic means inorganic compounds such as oxides, carbides, nitrides, borides and the like. For example, alumina (Al ₂ O ₃ ), silicon nitride (SiN), silicon carbide (SiC), aluminum nitride (AlN) ), Zirconium boride (ZrB ₂ ), and the like.

The process of forming a predetermined film or the like on the substrate using ink containing coated metal fine particles is not particularly limited as long as it can form a film with a desired thickness, and general spin coating, spray coating, etc. Can be used. In particular, the process of forming a pattern serving as a wiring precursor on the substrate by using a film containing coated fine metal particles can use various conventional printing methods such as a screen printing method, an ink jet printing method, and an intaglio plate. Printing, letterpress printing, lithographic printing, and the like can be used. Moreover, the use of the metal film obtained by making the film containing the coated metal fine particles into a conductor is not limited to electrical wiring, and can be used for mirror surfaces for optical devices, various decorations, and the like.
The thickness of the film formed on the substrate with the ink containing the coated metal fine particles can be appropriately set according to the purpose of the metal film obtained by making the conductor. If it is a normal electric wiring etc., a favorable characteristic can be acquired by forming a film | membrane with the said ink so that it may become a metal film of about 1 micrometer or less, and making it into a conductor.

From a different point of view, the present invention provides a wiring board including a step of applying metal fine particles coated with a protective film containing an alkylamine on a substrate, and a step of converting the coated metal fine particles into a conductor by the above method. Provide a method. The feature of the production method of the present invention is that when the metal fine particles covered with the protective film containing the alkylamine are used, the conductorization method described above is used. Accordingly, the substrate on which the coated metal fine particles are applied and the method for applying the same are not particularly limited. However, based on the characteristics of the present invention that enables a conductor to be formed at a low temperature, such as PET and polypropylene, which are easy to process and inexpensive. Wiring to the organic polymer substrate can be performed using the inkjet printing method.
In addition, the method for making a conductor according to the present invention can be used for forming a wiring for supplying power to various semiconductor materials provided on a substrate. In particular, the method for forming a conductor according to the present invention is particularly useful in the formation of wiring that feeds power to materials that are difficult to be heated to high temperatures, such as organic EL materials and organic semiconductor materials.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples regarding the method for forming a conductor according to the present invention, in particular, regarding the conversion of a film containing coated silver fine particles produced by a metal amine complex decomposition method. The invention is not limited to the following examples.

[Preparation Example 1] Preparation 1 of alkylamine-coated silver fine particles
n-hexylamine 5.78 g (57.1 mmol), n-dodecylamine 0.885 g (4.77 mmol), N, N-dimethyl-1,3-diaminopropane 3.89 g (38.1 mmol), oleic acid ( Tokyo Chemical,> 85.0%) 0.251 g (0.889 mmol) was mixed, and 7.60 g (25.0 mmol) of silver oxalate was added to this mixture, followed by stirring for about 1 hour. An amine / alkyl diamine / silver complex compound was formed and changed to a viscous solid. This was heated and stirred at 100 ° C. for 10 minutes to complete the reaction accompanied by the foaming of carbon dioxide, thereby obtaining a suspension containing coated silver fine particles exhibiting blue gloss. In order to remove excess alkylamine and the like contained in the suspension, 10 mL of methanol is added to the suspension, the precipitate obtained by centrifugation is separated, 10 mL of methanol is added again, and the precipitate is stirred. The precipitate was obtained by centrifugation. The precipitate was coated silver fine particles coated with a protective film containing alkylamine. To this precipitate, a mixed solvent of n-octane and n-butanol (volume ratio 4: 1 v / v) was added and stirred to obtain a dispersion 1 in which 50% by weight of coated silver fine particles were well dispersed.

[Preparation Example 2] Preparation 2 of alkylamine-coated silver fine particles
Octylamine 0.73 g (molar ratio to silver oxalate 0.56), hexylamine 3.46 g (same molar ratio 3.4), butylamine 1.45 g (same molar ratio 2.0), oleic acid (Tokyo Kasei, > 85.0%) 0.12 g was mixed, and 3.047 g of silver oxalate synthesized from silver nitrate (Kanto Chemical, first grade) and oxalic acid dihydrate (Kanto Chemical, special grade) By adding a molar ratio 1) and stirring at room temperature, the silver oxalate was changed to a viscous white substance, and stirring was terminated when the change was found to be apparently finished. The obtained mixed liquid was transferred to an aluminum block type heating stirrer and heated and stirred at a temperature setting of 100 to 110 ° C. Suspension in which coated silver fine particles exhibiting a blue luster are suspended in the amine mixture by stirring until carbon dioxide generation is completed immediately after the start of stirring and then stirring until carbon dioxide generation is completed. A liquid was obtained.

Next, in order to replace the dispersion medium of this suspension, 10 mL of methanol was added and stirred, and then the coated silver fine particles were precipitated and separated by centrifugation, and 10 mL of methanol was added again to the separated coated silver fine particles, The coated silver fine particles were precipitated and separated by stirring and centrifuging. To this coated silver fine particle, a mixed solvent of n-butanol and n-octane (volume ratio 1: 4) is added and stirred so that the silver content after mixing is about 50% by weight, and the coated silver fine particles are dispersed independently. Dispersion 2 was obtained.

[Test Example 1]
Using the coated silver fine particle dispersion 1 prepared in Preparation Example 1, a film containing the coated silver fine particles was formed on a PET substrate by spin coating so that the film thickness after the formation of the conductor was about 500 nm. The substrate on which the film was formed was quickly placed in a constant temperature oven set at 40 ° C. in a forced air dryer (Yamato DK240S or DKM300), and the electrical resistance after one hour (four probe method, Kyowa Riken K- 705RS) was measured (Comparative Example 1). The relative humidity in the thermostatic chamber at this time was 11% (temperature / humidity / anemometer sensor (A1-SDI Status V2, manufactured by ASONE CORPORATION)).
A film containing coated silver fine particles was formed on a PET substrate by spin coating in the same manner as described above except that the dispersion 2 of coated silver fine particles prepared in Preparation Example 2 was used. The substrate on which the film was formed was quickly placed in a thermostatic oven set at 80 ° C. in a forced air dryer, and the electrical resistance after 1 hour was measured in the same manner (Comparative Example 2). At this time, the relative humidity in the thermostatic chamber was 2.7%.
Table 1 shows the electrical resistance values of the films that were made conductive under the respective conditions. In Table 1, values obtained by converting each relative humidity into a volumetric absolute humidity are also shown.
This test example is an example in which the atmosphere in the laboratory heated to a substantially predetermined temperature is brought into contact with a film containing coated silver fine particles, and is made into a conductor. Compared with the examples described below, Even when conducting at 1 ° C. for 1 hour, the volume resistivity could not be lowered sufficiently, and it was inferred that the alkylamine contained in the protective film of the coated silver fine particles remained inside the film.

[Test Example 2]
In the same manner as in Test Example 1, a film was formed using Dispersion 1, and the substrate was quickly placed in a constant temperature and humidity chamber (ESPEC environmental tester, SH-221) that was kept under predetermined conditions for 1 hour. Changes in resistance (four probe method) were measured. The temperature and humidity conditions were constant at 40 ° C., and the relative humidity was 38% (Example 1), 50% (Example 2), 60% (Example 3) and 80% (Example 4), respectively. It was.
Table 1 also shows the electrical resistance values of the films that have been made conductive under the respective conditions. Moreover, the time-dependent change of the electrical resistance value during conductorization in Examples 1, 3, and 4 is shown in FIG. As can be seen from Table 1 and FIG. 1, the higher the humidity, the more the film containing the coated silver fine particles becomes conductive, and even at an extremely low temperature of 40 ° C., the conductor becomes 73 μΩcm (relative humidity 80%) after 1 hour. Since a silver film having a high degree of conductivity was obtained, it was shown that the elimination of the alkylamine that had formed the protective film of the coated silver fine particles was promoted.

[Test Example 3]
The temperature in the thermo-hygrostat is constant at 50 ° C., relative humidity 35% (Example 5), relative humidity 50% (Example 6), relative humidity 60% (Example 7), and relative humidity 70% (Example) 8) and a relative humidity of 80% (Example 9) except that the electrical resistance was measured in the same manner as in Test Example 1 except that the film of the dispersion liquid 1 provided on the PET substrate was made conductive. .
Table 1 also shows the electrical resistance values of the films made into conductors for 1 hour under the respective conditions. In addition, FIG. 2 shows the change over time of the electrical resistance value during the conductorization in Examples 5 to 9. In any relative humidity, the volume resistivity becomes 10 ⁻⁴ Ωcm or less within 1 hour, and the volume resistivity decreases particularly when contacted with a high proportion of water vapor, and the elimination of alkylamine is promoted. Conceivable.

[Test Example 4]
Test example, except that the temperature in the constant temperature and humidity chamber was fixed at 70 ° C. and the relative humidity was set to 30% (Example 10), relative humidity 40% (Example 11), and relative humidity 50% (Example 12). In the same manner as in No. 1, the film of the dispersion 1 provided on the PET substrate was subjected to a conductor treatment, and the electrical resistance was measured.
Table 1 also shows the electrical resistance values of the films made into conductors for 30 minutes under the respective conditions. In addition, FIG. 3 shows the change over time of the electrical resistance value during the conductorization in Examples 10 to 12. At any relative humidity, the volume resistivity becomes 10 ⁻⁴ Ωcm or less in a short time of about 1 minute from the start of the conductorization treatment, and the decrease in volume resistivity tends to be large due to the conductorization at high humidity, It was speculated that the elimination of the alkylamine contained in the protective film of the coated silver fine particles occurs in a very short time.

[Test Example 5]
On the PET substrate in the same manner as in Test Example 1, except that the relative humidity in the constant temperature and humidity chamber was fixed at 50% and the temperature was set to 60 ° C. (Example 13) and 80 ° C. (Example 14). Conductive treatment was performed on the membrane of Dispersion 1 provided on the substrate, and the electrical resistance was measured.
Table 1 also shows the electrical resistance values of the films made into conductors for 30 minutes under the respective conditions. In addition, FIG. 4 shows the change over time in the electrical resistance value during conductorization in Examples 13 and 14. Even at the same relative humidity, the reason why conductorization is promoted in conductorization at 80 ° C as compared to 60 ° C is that the vapor pressure of alkylamine and the like contained in the protective film increases as the temperature rises, This is probably because the volumetric absolute humidity representing the substantial amount of water vapor in the gas phase increases, and the supply of water molecules to the film containing the coated silver fine particles becomes smooth.

[Test Example 6]
Using the coated silver fine particle dispersion 2 prepared in Preparation Example 2, a film containing the coated silver fine particles was formed on the PET substrate by spin coating in the same manner as described above. The substrate on which the film was formed was quickly placed in a thermostatic oven set at 120 ° C. in a forced air dryer, and the electrical resistivity after 30 minutes was measured in the same manner (Example 15). At this time, the vicinity of the air inlet of the forced air dryer was humidified, and the relative humidity in the thermostatic bath was 3.3%.
Table 1 also shows the electrical resistance value of the film made conductive in Example 15. The volumetric absolute humidity in the thermostatic chamber in Example 15 was converted to 36.7 g / m ^3, and a silver thin film having an extremely low volume resistivity of 11 μΩcm, which is close to the resistance value of ideal metallic silver, was obtained.

[Test Example 7]
Using the coated silver fine particle dispersion 2 prepared in Preparation Example 2, a film containing the coated silver fine particles was formed on the PET substrate by spin coating in the same manner as described above. The substrate on which the film was formed was quickly placed in a separable flask at room temperature (20 ° C.), and air bubbled with water was circulated through the separable flask, and the electrical resistivity after 1 hour was measured in the above test example. Was measured in the same manner. At this time, the relative humidity inside the separable flask was 86%. Next, the substrate was quickly placed in a thermostatic oven set at 80 ° C. in a forced air dryer, and the electrical resistivity after 1 hour was measured in the same manner (Example 16). At this time, the relative humidity in the thermostatic chamber was 3.8%.

Table 1 also shows the electrical resistance values of the films made conductive in Example 16. In Example 16, an extremely low volume resistivity of about 10 μΩcm was measured even though the substantial conductorization treatment at 80 ° C. was performed under the same conditions as in Comparative Example 2. This is because water molecules are adsorbed on the film containing the coated silver fine particles by contact with air of relatively high humidity in advance at 20 ° C., and the alkyl contained in the protective film of the coated silver fine particles by the water molecules. It was assumed that the elimination of amines was promoted.

The above results are summarized as shown in Table 1 below.

[Test Example 8]
Dispersion liquid 1 obtained in Preparation Example 1 was applied on a silicon substrate in the same manner as in Test Example 1. FIG. 5 shows the result of observing the cross section of the film after making it a conductor under the same conditions as in Example 12 using a thermal field emission scanning electron microscope (JEOL JSM-7600F). It can be seen that a dense film is formed with a film thickness of about 500 nm. In addition, the surface of the film forms a very smooth mirror surface, which is expected to be used as a mirror surface for various optical applications.

As described above, when a film containing coated metal fine particles coated with a protective film containing alkylamine is made into a conductor, as supported by each example, the film is brought into contact with a gas containing a predetermined amount or more of water vapor. It became clear that the conductorization was promoted. This is presumed to be because desorption of the alkylamine contained in the protective film is promoted by the adsorption and incorporation of water vapor contained in the gas into the film. Typically, it has been clarified that the inclusion of water vapor of 14 g / m ³ or more as the absolute volume humidity produces an advantageous effect in terms of conductorization treatment.

Claims

A method for converting a film containing coated metal fine particles provided on a substrate and coated with a protective film containing an alkylamine into a conductor, at least a part of the film containing the coated metal fine particles, and 14 g / m A method for making a conductor, comprising a step of contacting a gas containing three or more water vapors.
And some even less of a film containing the fine metal particles, in some even less of contacting a gas containing 14 g / m 3 or more of water vapor, the gas containing 20 g / m 3 or more steam The method according to claim 1, wherein the film is brought into contact with the film.
The step of contacting at least a part of the film containing the coated fine metal particles with a gas containing water vapor of 14 g / m 3 or more was covered with a protective film containing an alkylamine provided on the substrate. 3. The method for forming a conductor according to claim 1, wherein the method is carried out in almost all methods for converting a film containing coated metal fine particles into a conductor.
The coated metal fine particles coated with a protective film containing an alkylamine are produced by thermally decomposing a complex compound containing a metal compound in the presence of an alkylamine. The conductorization method according to any one of the above.
5. The method of forming a conductor according to claim 4, wherein the coated metal fine particles coated with a protective film containing an alkylamine are coated silver fine particles coated with a protective film containing an alkylamine.
A substrate having a conductor film in which a film containing coated metal fine particles is made into a conductor by the method for forming a conductor according to any one of claims 1 to 5.