JP7102725B2 - Structure and its manufacturing method - Google Patents

Description

The present invention relates to a structure and a method for producing the same.

As a method for forming a structure for ensuring continuity, a step of forming a conductive layer made of a conductive material on a base material using a conductive material such as ink or paste containing metal particles, and a step of heating the conductive layer to make a metal A method including a conductor-forming step of sintering particles to develop conductivity is known. As the metal particles contained in the conductive material, those in which an organic substance as a coating material is attached to the surface in order to suppress the oxidation of the metal and improve the storage stability are known (for example, Patent Document 1 and Patent Document 2). reference).

Japanese Unexamined Patent Publication No. 2012-0272418 Japanese Unexamined Patent Publication No. 2012-226856

However, a sintered body obtained by sintering metal particles may not have sufficient adhesion depending on the base material, and conduction may not be ensured. Further, the base materials used in recent years have been diversified, and improvement of the adhesion between the base material and the sintered body has become an issue.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for producing a structure having excellent adhesion between a base material and a sintered body of metal particles.

The present invention provides a method for producing a structure shown in the following [1] to [5] and a structure shown in the following [6].

[1] A step of arranging a first composition containing a polyisocyanate on a substrate and a step of arranging a second composition containing copper-containing particles and a polyol on the arranged first composition. A method for producing a structure, comprising a step of polymerizing a polyisocyanate and a polyol and sintering copper-containing particles by heat-treating the first composition and the second composition.
[2] The method for producing a structure according to [1], wherein the copper-containing particles have copper-containing core particles and an organic substance that covers at least a part of the surface of the core particles.
[3] The method for producing a structure according to [1] or [2], wherein the polyisocyanate contains diphenylmethane diisocyanate or polymethylene polyphenyl polyisocyanate.
[4] The method for producing a structure according to any one of [1] to [3], wherein the polyol contains ethylene glycol, propylene glycol, or a dehydration condensate thereof.
[5] The method for producing a structure according to any one of [1] to [4], wherein the heat treatment temperature is 100 ° C. to 250 ° C.
[6] A structure comprising a base material and a sintered body obtained by sintering copper-containing particles provided on the base material via a polymer of polyisocyanate and polyol.

According to the present invention, there is provided a method for producing a structure having excellent adhesion between a base material and a sintered body of metal particles. Further, a structure obtained by such a manufacturing method is provided.

It is a cross-sectional enlarged image at the interface of the structure produced in Example 1.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

The numerical range indicated by using "-" in the present specification indicates a range including the numerical values before and after "-" 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 otherwise specified, when a plurality of substances corresponding to each component are present in the composition. Means.

In the present specification, the term "process" is included in this term not only as an independent process but also as long as the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes.

As used herein, the term "layer" or "film" includes not only a shape structure formed on the entire surface but also a shape structure formed on a part thereof when observed as a plan view.

As used herein, the term "conductor" means that metal-containing particles are sintered and transformed into a conductive object. The "conductor" means an object having conductivity, and more specifically, an object having a volume resistivity of 1000 μΩ · cm or less.

As used herein, the term "polyisocyanate" means a compound having two or more isocyanate groups in the molecule. Further, in the present specification, the “polyol” means a compound having two or more hydroxyl groups in the molecule.

<Manufacturing method of structure>
The method for producing a structure according to one embodiment includes a step of arranging a first composition containing polyisocyanate on a base material (first arranging step) and a step of arranging the first composition on the arranged first composition. The polyisocyanate and the polyol are polymerized by the step of arranging the second composition containing the copper-containing particles and the polyol (the second arranging step) and the heat treatment of the first composition and the second composition. A step of sintering the copper-containing particles (heat treatment step) is provided.

According to such a method for producing a structure, it is possible to produce a structure having excellent adhesion between the base material and the sintered body of metal particles. The present inventor considers the reason why such an effect is exhibited as follows. The isocyanate group is highly reactive and easily condenses with a functional group such as a hydroxyl group. Therefore, the first composition containing the polyisocyanate is placed on the substrate, and then the second composition containing the copper-containing particles and the polyol is placed and heat-treated to obtain the isocyanate group and the polyol of the polyisocyanate. It is presumed that the hydroxyl groups are condensed to form a polymer (a polymer having a urethane bond), and at the same time, a sintered body formed of copper-containing particles is formed on the substrate via the formed polymer. To. The formed polymer can contribute to the adhesion between the base material and the sintered body of the metal particles.

(First placement process)
The method for producing a structure according to the present embodiment includes a step of arranging a first composition containing a polyisocyanate on a base material.

The material of the base material is not particularly limited and may or may not have conductivity. Examples of the material of the base material include metals such as copper, gold, platinum n, palladium, silver, zinc, nickel, cobalt, iron, aluminum and tin, alloys of these metals, indium tin oxide, zinc oxide and zinc oxide. , Indium gallium oxide Semiconductors such as zinc, silicon, silicon carbide, gallium nitride, glass such as quartz glass, borosilicate glass, soda lime glass, carbon materials such as graphite and graphite, resins, paper and the like. The shape of the base material is not particularly limited, and may be plate-shaped, rod-shaped, roll-shaped, film-shaped, or the like.

When the copper-containing particles have a core particle containing copper and an organic substance that covers at least a part of the surface of the core particle, the conductor can be formed at a relatively low temperature (for example, 150 ° C. or lower). A material having low heat resistance can be used as a base material. Examples of such a base material include a base material made of a thermoplastic resin. Thermoplastic resins include polyethylene, polypropylene, polymethylpentene, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyvinyl chloride, polystyrene, ABS, methyl poly (meth) acrylate, polyamide, polycarbonate, polyphenylene sulfide, and polyphenylene oxide. , Polytetrafluoroethylene, polyacrylonitrile and the like.

The substrate is preferably thoroughly cleaned prior to the first placement step. Examples of the method for cleaning the base material include a method for cleaning with a cleaning liquid containing an organic solvent or water, a method for irradiating the surface of the base material with ultraviolet rays, and the like.

The first composition comprises a polyisocyanate. Examples of the polyisocyanate include diphenylmethane diisocyanates such as 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and 4,4'-diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, toluene-2,4-diisocyanate, and the like. Examples thereof include toluene diisocyanate such as toluene-2,6-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, lysine triisocyanate, methylsilane triyltrisocyanate, and polymethylene polyphenyl polyisocyanate. These may be used individually by 1 type or in combination of 2 or more type. Among these, the polyisocyanate preferably contains diphenylmethane diisocyanate or polymethylene polyphenyl polyisocyanate.

The content of the polyisocyanate may be 0.1% by mass or more, 0.3% by mass or more, or 1% by mass or more based on the total amount of the first composition. When the content of the polyisocyanate is 0.1% by mass or more, the adhesion to the substrate tends to be better. The content of the polyisocyanate may be 100% by mass or less, 80% by mass or less, or 60% by mass or less based on the total amount of the first composition. When the content of the polyisocyanate is 80% by mass or less, the application of the first composition tends to be easier.

The first composition may contain other components such as an inorganic filler and a cross-linking agent. It may be silica, alumina, silicon nitride, aluminum nitride, boron nitride or the like. The cross-linking agent may be a silane coupling agent or the like. The content of other components may be 0.1 to 10 parts by mass with respect to 100 parts by mass of polyisocyanate.

The first composition may be used as a first composition varnish diluted with a first solvent. The arrangement of the first composition can be performed, for example, by applying the first composition varnish on the substrate. The first solvent is, for example, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, aromatic compounds such as toluene and xylene, chain hydrocarbons such as butane, pentane, hexane, heptane and octane, ethyl acetate and acetic acid. It may be an ester such as propyl or butyl acetate, or a cyclic compound such as cyclohexane, methylcyclohexane or cyclohexanone. These first solvents may be used alone or in combination of two or more. Among these, the first solvent may be toluene, xylene, or ethyl acetate.

The content of the first solvent in the first composition varnish may be 0 to 100,000 parts by mass, 10 to 30,000 parts by mass, or 50 to 10,000 parts by mass with respect to 100 parts by mass of polyisocyanate. When the content of the first solvent is in such a range, the dispersibility is better and the coating can be more efficiently applied on the substrate.

The first composition varnish can be prepared by mixing and kneading the polyisocyanate and other components, and the first solvent. Mixing and kneading are performed by Ishikawa stirrer, rotating and revolving stirrer, ultra-thin high-speed rotary disperser, roll mill, ultrasonic disperser, media disperser such as bead mill, and cavitation stirrer such as homomixer and Silberson stirrer. , An anti-collision device such as an artemizer can be appropriately combined.

As the first composition varnish, a commercially available product can be used as it is. Examples of such a commercially available product include K-500 (trade name, 3M Japan Ltd.) and the like. These may be further diluted with the above-mentioned first solvent and used.

The method for applying the first composition varnish is not particularly limited, and a known method can be applied. Examples of such a method include an inkjet method, a super inkjet method, a screen printing method, a transfer printing method, an offset printing method, a jet printing method, a dispensing method, a jet dispensing method, a needle dispensing method, a comma coating method, and a bar coating method. , Slit coating method, die coating method, gravure coating method, letterpress printing method, concave printing method, gravure printing method, soft lithograph method, dip pen lithograph method, particle deposition method, spray coating method, spin coating method, dip coating method, electric Examples include a dressing method.

After applying the first composition varnish on the substrate, a part or all of the first solvent contained in the first composition varnish may be removed by drying. The drying conditions may be room temperature (25 ° C.) to 80 ° C.

The thickness of the first composition arranged after drying can be appropriately set depending on the intended purpose, but may be, for example, 0.2 to 50 μm, and from the viewpoint of adhesion, 0.5 μm to 0.5 μm. It is more preferably 20 μm.

(Second placement process)
The method for producing a structure according to the present embodiment includes a step of arranging a second composition containing copper-containing particles and a polyol on the arranged first composition.

The second composition comprises copper-containing particles. The copper-containing particles preferably contain copper as a main component from the viewpoint of thermal conductivity and sinterability. The element ratio of copper in the copper-containing particles may be 80 atomic% or more, 90 atomic% or more, or 95 atomic% or more based on all elements except hydrogen, carbon, and oxygen. When the element ratio of copper is 80 atomic% or more, the thermal conductivity and sinterability derived from copper tend to be easily exhibited.

The copper-containing particles may be copper-containing particles having core particles containing copper and an organic substance that covers at least a part of the surface of the core particles. The copper-containing particles may include, for example, copper-containing core particles and an organic substance containing a substance derived from an alkylamine present on at least a part of the surface of the core particles. The alkylamine may be an alkylamine having 7 or less carbon atoms in the hydrocarbon group. Since the chain length of the hydrocarbon group of the alkylamine constituting the organic substance is relatively short, the copper-containing particles are thermally decomposed even at a relatively low temperature (for example, 150 ° C. or lower), and the core particles tend to be easily fused to each other. It is in. As such copper-containing particles, for example, the copper-containing particles described in JP-A-2016-037627 can be preferably used.

The organic substance may contain an alkylamine having 7 or less carbon atoms in the hydrocarbon group. The alkylamine having 7 or less carbon atoms in the hydrocarbon group may be, for example, a primary amine, a secondary amine, an alkylenediamine or the like. Examples of the primary amine include ethylamine, 2-ethoxyethylamine, propylamine, 3-ethoxypropylamine, butylamine, 4-methoxybutylamine, isobutylamine, pentylamine, isopentylamine, hexylamine, cyclohexylamine, heptylamine and the like. be able to. Examples of the secondary amine include diethylamine, dipropylamine, dibutylamine, ethylpropylamine, ethylpentylamine and the like. Examples of the alkylenediamine include ethylenediamine, N, N-dimethylethylenediamine, N, N'-dimethylethylenediamine, N, N-diethylethylenediamine, N, N'-diethylethylenediamine, 1,3-propanediamine, and 2,2-dimethyl-. 1,3-Propane diamine, 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, 1,7-diaminoheptane and the like can be mentioned. ..

The organic substance that covers at least a part of the surface of the core particles may contain an organic substance other than the alkylamine having 7 or less carbon atoms in the hydrocarbon group. The ratio of the alkylamine having 7 or less carbon atoms in the hydrocarbon group to the entire organic substance is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more. preferable.

The proportion of the organic matter covering at least a part of the surface of the core particles is preferably 0.1 to 20% by mass with respect to the total of the core particles and the organic matter. When the proportion of organic matter is 0.1% by mass or more, sufficient oxidation resistance tends to be obtained. When the proportion of organic matter is 20% by mass or less, conductor formation at low temperature tends to be easily achieved. The ratio of the organic matter to the total of the core particles and the organic matter is more preferably 0.3 to 10% by mass, further preferably 0.5 to 5% by mass.

The copper-containing particles contain at least copper and may contain other substances as needed. Examples of other substances include metals such as gold, silver, platinum, tin and nickel, compounds containing these metal elements, reducing compounds or organic substances, oxides, chlorides and the like. From the viewpoint of forming a conductor having excellent conductivity, the content of copper in the copper-containing particles is preferably 50% by mass or more, more preferably 60% by mass or more, and more preferably 70% by mass or more. Is even more preferable.

The shape of the copper-containing particles is not particularly limited. For example, spherical, long-granular, flat, fibrous, etc. can be mentioned and can be selected according to the use of the copper-containing particles. From the viewpoint of using as a printing paste, it is preferably spherical and long-granular.

Since organic substances are present on at least a part of the surface of the copper-containing particles, the oxidation of copper is suppressed even during storage in the air, and it is presumed that the oxide content is small. For example, the content of oxides in the copper-containing particles may be 5% by mass or less. The content of oxides in the copper-containing particles can be measured by, for example, XRD.

The method for producing the copper-containing particles is not particularly limited. Examples of the production method include the method for producing copper-containing particles described in JP-A-2016-037627.

The content of the copper-containing particles may be 20% by mass or more, 30% by mass or more, or 40% by mass or more based on the total amount of the second composition. When the content of the copper-containing particles is 20% by mass or more, the resistance value of the sintered body obtained by sintering tends to decrease. The content of the copper-containing particles may be 99% by mass or less, 95% by mass or less, or 90% by mass or less based on the total amount of the first composition. When the content of the copper-containing particles is 99% by mass or less, the application of the second composition tends to be easier.

The second composition comprises a polyol. The polyol can react with the polyisocyanate contained in the first composition described above to form a polymer (a polymer having a urethane bond). Examples of the polyol include dihydric alcohols, trihydric alcohols, tetrahydric alcohols and the like. The polyol may be used alone or in combination of two or more.

Examples of the divalent alcohol include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, polypropylene glycol, polytetramethylene ether glycol, 1, 3-Propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,2-pentanediol, 1,3-pentanediol , 1,4-pentanediol, 1,5-pentanediol, neopentyl glycol, 2-methyl-1,2-butanediol, 3-methyl-1,2-butanediol, 1,2-hexanediol, 1, 3-Hexanediol, 1,6-hexanediol, 2,5-hexanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,3-pentane Glycol, 1,2-heptanediol, 1,7-heptanediol, 3,5-heptanediol, 1,2-octanediol, 1,8-octanediol, 2-ethyl-1,3-hexanediol, 2, Examples thereof include 5-dimethyl-2 and 5-hexanediol.

Examples of trihydric alcohols include glycerin, trimethylolmethane, trimethylolethane, trimethylolpropane, 1,2,3-butanetriol, 1,2,4-butanetriol, 2-methyl-1,2,3-. Propanetriol, 2-methyl-2,3,4-butanetriol, 2-methyl-1,2,4-butanetriol, 1,2,3-pentantriol, 2,3,4-pentantriol, 1,3 , 4-Pentantriol, 1,2,5-Pentantriol, 1,2,6-Hexanetriol, 1,2,3-Hexanetriol, 2,3,4-Hexanetriol, 3-Methyl-1,2, Examples thereof include 5-pentantriol and 3-methyl-1,3,5-pentantriol.

Examples of the tetrahydric alcohol include erythritol, threitol, pentaerythritol, ditrimethylolpropane and the like.

Among these, the polyol preferably contains ethylene glycol, propylene glycol, or a dehydrated condensate thereof.

The content of the polyol may be 0.05 to 300 parts by mass, 0.1 to 150 parts by mass, or 0.5 to 100 parts by mass with respect to 100 parts by mass of the copper-containing particles. When the content of the polyhydric alcohol is 300 parts by mass or less, better storage stability tends to be obtained. Further, when the content of the polyhydric alcohol is 0.05 parts by mass or more, the adhesion of the obtained sintered body to the base material tends to be more excellent.

The second composition may contain other components such as an inorganic filler, a cross-linking agent, and a curable resin. As the inorganic filler and the cross-linking agent, the same components as those exemplified in the first composition can be exemplified.

The curable resin can contribute to the improvement of the adhesion between the obtained sintered body and the base material and the suppression of oxidation of the sintered body. Examples of the curable resin include phenol resin, epoxy resin, melamine resin, urea resin, polyester resin, alkyd resin, urethane resin, polyimide resin, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose and the like. The second composition may contain a curing agent for curing the curable resin, or may contain a curing accelerator for accelerating the curing. The content of the other components may be 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the copper-containing particles.

The second composition may be used as a second composition varnish diluted with a second solvent. The placement of the second composition can be done, for example, by applying a second composition varnish onto the first composition. The second solvent can be appropriately selected from those generally used in the production of conductive inks, conductive pastes, etc., depending on the application. For example, monohydric alcohols such as terpineol, isobornylcyclohexanol, dihydroterpineol, dihydroterpineol acetate, etc. It may be an ester of. These second solvents may be used alone or in combination of two or more. Among these, the second solvent may be terpineol, isobornylcyclohexanol, or dihydroterpineol.

The content of the second solvent in the second composition varnish may be 1 to 500 parts by mass, 3 to 300 parts by mass, or 5 to 200 parts by mass with respect to 100 parts by mass of the polyol. When the content of the second solvent is in such a range, the dispersibility is better and the coating can be more efficiently applied on the substrate.

The second composition varnish can be prepared by mixing and kneading copper-containing particles, a polyol, a second solvent, and other components. Mixing and kneading may be carried out in the same manner as in the first composition varnish.

The method for applying the second composition varnish is not particularly limited, and the known method exemplified in the method for applying the first composition varnish can be applied.

After applying the second composition varnish on the first composition, a part or all of the second solvent contained in the second composition varnish may be removed by drying. The drying conditions may be room temperature (25 ° C.) to 80 ° C.

The thickness of the arranged second composition after drying can be appropriately set depending on the intended purpose, but may be, for example, 0.1 to 100 μm, and from the viewpoint of adhesion, 0.5 μm to 0.5 μm. It is more preferably 20 μm.

(Heat treatment process)
The method for producing a structure according to the present embodiment includes a step of polymerizing polyisocyanate and polyol and sintering copper-containing particles by heat-treating the first composition and the second composition.

The temperature of the heat treatment step is not particularly limited as long as the polyisocyanate and the polyol can be polymerized (polyurethane is produced as a polymer) and the copper-containing particles can be sintered, but the temperature is 100 ° C. to 250 ° C. Is preferable, and the temperature is more preferably 120 to 230 ° C. When the temperature of the heat treatment step is 100 ° C. or higher, a sintered body having more sufficient conductivity tends to be obtained.

The heat treatment step may be performed at a constant heating rate or may be changed 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 5 minutes to 120 minutes from the viewpoint of achieving both sufficient conductivity and mass productivity. When the heat treatment time is 5 minutes or more, sufficient conductor formation tends to be possible, and when it is 120 minutes or less, it is preferable from the viewpoint of mass productivity. The heating method is not particularly limited, and heating can be performed using a hot plate, an infrared heater, a pulse laser, or the like.

The gas atmosphere in the heating step may be any gas atmosphere of an inert gas such as nitrogen and argon, a reducing gas such as hydrogen and formic acid, or a mixed gas of these inert gas and reducing gas. .. By performing the heat treatment in an inert gas atmosphere, it is possible to suppress the formation of copper oxide on the surface of the copper-containing particles. Further, when the surface of the copper-containing particles is coated with an organic substance by heat treatment with a reducing gas, the organic substance can be easily detached, and the core particles containing copper of the particles are sintered (fused). When the base material contains a metal, it is possible to promote the sintering (fusion) of the metal and the copper contained in the core particles.

The atmospheric pressure condition of the atmosphere in the heating step is not particularly limited and may be an atmospheric pressure condition or a reduced pressure condition, but the reduced pressure condition tends to further promote the formation of a conductor at a low temperature.

The structure manufacturing method according to the present embodiment may include other steps, if necessary. Other steps include, after the heat treatment step, for example, a step of reducing the oxide by heat treatment in a reducing atmosphere, a step of removing residual components by light firing, a step of applying a load, and plating by electrolytic plating or electroless plating. Examples include the process of processing.

<Structure>
The structure according to one embodiment includes a base material and a sintered body obtained by sintering copper-containing particles provided on the base material via a polymer of polyisocyanate and polyol. It is presumed that the structure has improved adhesion because the base material and the sintered body provided on the base material are interposed through the polymer.

The volume resistivity of the sintered body is required to be an optimum value according to the application, but may be 500 μΩ · cm or less, 200 μΩ · cm or less, or 100 μΩ · cm or less.

The shape of the sintered body is not particularly limited, and may be a thin film shape, a bump shape, a pattern shape, or the like. The structure can be used for wiring of various electronic components and the like. In particular, since the structure can be manufactured at a relatively low temperature, it is suitable for forming a metal foil, a connection terminal, a wiring pattern, or the like on a base material having low heat resistance.

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited thereto.

(Production Example 1: Synthesis of copper nonanoate)
To 91.5 g (0.94 mol) of copper hydroxide (Kanto Chemical Co., Inc., special grade), 150 mL of 1-propanol (Kanto Chemical Co., Inc., special grade) was added and stirred, and nonanoic acid (Kanto Chemical Co., Inc., 90%) was stirred. Above) 370.9 g (2.34 mol) was added. The resulting mixture was heated and stirred in a separable flask at 90 ° C. for 30 minutes. The obtained solution was filtered while being heated to remove undissolved substances. After that, 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% by mass).

(Production Example 2: Synthesis of Copper-Containing Particles)
15.01 g (0.040 mol) of copper (II) nonanoate and 7.21 g (0.040 mol) of copper (II) acetate anhydride (Kanto Kagaku Co., Ltd., special grade) obtained above were placed in a separable flask. 22 mL of 1-propanol and 32.1 g (0.32 mol) of hexylamine (Tokyo Kasei Kogyo Co., Ltd.) were added, and the mixture was dissolved by heating and stirring at 80 ° C. in an oil bath. After transferring to an ice bath and cooling to an internal temperature of 5 ° C., 7.72 mL (0.16 mol) of hydrazine monohydrate (Kanto Chemical Co., Inc., special grade) was added, and the mixture was further stirred in the ice bath. The molar ratio of copper: hexylamine is 1: 4. Then, it was heated and stirred at 90 ° C. for 10 minutes in an oil bath. At that time, the reduction reaction accompanied by foaming proceeded, the inner wall of the separable flask exhibited a copper luster, and the solution turned dark red. Centrifugation was performed at 9000 rpm (rotation / min) for 1 minute to obtain a solid. The step of further washing the solid material with 15 mL of hexane was repeated three times to remove the acid residue to obtain a copper cake containing a powder of copper-containing particles having a copper luster.

(Example 1)
As a base material, a polyethylene naphthalate film (trade name: Theonex, Teijin Film Solution Co., Ltd.) was used. Primer containing 4,4'-diphenylmethane diisocyanate (MDI) and polymethylene polyphenyl polyisocyanate as polyisocyanate on this base material (trade name: K-500, 3M Japan Co., Ltd., solid content: about 8% by mass) , Dispersion medium: toluene) (first composition varnish) was applied using a bar coater and dried at room temperature (25 ° C.) to place the first composition on the substrate.

Next, 70 parts by mass of the obtained copper cake, 15 parts by mass of terpineol (Wako Pure Chemical Industries, Ltd.) as a second solvent, and 15 parts by mass of diethylene glycol (Tokyo Kasei Kogyo Co., Ltd.) as a polyol were rotated and revolved. A second composition varnish containing copper-containing particles and a polyol was prepared by mixing with a formula stirrer (trade name: Rentaro Awatori, Shinky Co., Ltd.). The second composition is then placed on the first composition by applying the second composition varnish onto the first composition using a bar coater and drying at room temperature (25 ° C.). did.

The base material on which the first composition and the second composition are arranged is heat-treated using an atmosphere-controlled heat-bonding device (RF-100B, Ayumi Kogyo Co., Ltd.), polyisocyanate and polyol are polymerized, and copper is contained. The structure was made by sintering the particles. The heat treatment is performed by heating to 180 ° C. at a heating rate of 30 ° C./min at a negative pressure (8.5 × 10 ⁴ Pa) under a nitrogen gas atmosphere, and then a mixed gas of nitrogen and formic acid is introduced and 9.0. It was carried out by setting a mixed gas atmosphere of × 10 ⁴ Pa and holding at 180 ° C. for 60 minutes.

(Example 2)
In the second composition varnish, a structure was prepared in the same manner as in Example 1 except that diethylene glycol was changed to triethylene glycol (Tokyo Chemical Industry Co., Ltd.).

(Example 3)
In the second composition varnish, a structure was prepared in the same manner as in Example 1 except that diethylene glycol was changed to polyethylene glycol 200 (Tokyo Chemical Industry Co., Ltd.).

(Comparative Example 1)
A structure was prepared in the same manner as in Example 1 except that the first composition was not arranged.

(Comparative Example 2)
In the second composition varnish, a structure was prepared in the same manner as in Example 1 except that 15 parts by mass of terpineol and 15 parts by mass of diethylene glycol were changed to 30 parts by mass of terpineol.

(Comparative Example 3)
In the second composition varnish, a structure was prepared in the same manner as in Example 1 except that diethylene glycol was changed to isobornylcyclohexanol (trade name: Telsolv MTPH, Nippon Telpen Chemical Co., Ltd.).

(Comparative Example 4)
In the first composition varnish, the primer is changed to a mixed solution in which the prima and diethylene glycol are mixed at a mass ratio of 3: 1, and in the first arrangement step, the drying conditions of the first composition varnish are set to 5 at 80 ° C. A structure was prepared in the same manner as in Example 1 except that the amount was changed to 30 parts by mass and 15 parts by mass of terpineol and 15 parts by mass of diethylene glycol were changed to 30 parts by mass of terpineol in the second composition varnish.

Adhesion tests and volume resistivity measurements were performed on the obtained structures of Examples 1 to 3 and Comparative Examples 1 to 4.

<Adhesion test>
The adhesion between the sintered body and the base material was evaluated by a 2 mm square cross-cut test in accordance with JIS K5600 (1999). In all grids, "A" if there is no peeling, "B" if there is a small peeling at the intersection of the cut, "C" if there is peeling at the intersection along the line of the cut, part The case where there was a target or total peeling was evaluated as "D". The results are shown in Table 1.

<Measurement of volume resistivity>
In the above adhesion test, the volume resistivity of the sintered body was measured for the one evaluated as "A". The volume resistance is the surface resistance value measured by a 4-end needle surface resistance measuring instrument (trade name: Loresta GP MCP-T610, Mitsubishi Chemical Analytech Co., Ltd.) and a contact type step meter (trade name: ET200, It was calculated from the film thickness obtained by Kosaka Research Institute Co., Ltd.). The results are shown in Table 1.

<Cross section observation>
The cross section of the structure of Example 1 was observed using a focused ion beam processing observation device (FB-2000A, Hitachi High-Technologies Corporation). FIG. 1 shows an enlarged cross-sectional image of the structure produced in Example 1 at the interface. As shown in FIG. 1, it was found that in the structure of Example 1, a sintered body was present via a polymer of polyisocyanate and polyol.

As described above, the structures of Examples 1 to 3 had excellent adhesion and had a sufficiently low volume resistivity as compared with the structures of Comparative Examples 1 to 3. On the other hand, when the first composition contains polyisocyanate and polyol as in Comparative Example 4, it was found that the adhesion obtained by the structures of Examples 1 to 3 could not be obtained. As shown by these results, it was confirmed that the structure obtained by the production method of the present invention has excellent adhesion between the base material and the sintered body of the metal particles.

Claims (5)

A step of arranging a first composition containing a polyisocyanate on a substrate, and
A step of arranging a second composition containing copper-containing particles and a polyol on the arranged first composition, and a step of arranging the second composition.
A step of polymerizing the polyisocyanate and the polyol by heat-treating the first composition and the second composition, and sintering the copper-containing particles.
A method of manufacturing a structure. The method for producing a structure according to claim 1, wherein the copper-containing particles have core particles containing copper and an organic substance that covers at least a part of the surface of the core particles. The method for producing a structure according to claim 1 or 2, wherein the polyisocyanate contains diphenylmethane diisocyanate or polymethylene polyphenyl polyisocyanate. The method for producing a structure according to any one of claims 1 to 3, wherein the polyol contains ethylene glycol, propylene glycol, or a dehydration condensate thereof. The method for producing a structure according to any one of claims 1 to 4, wherein the heat treatment temperature is 100 ° C. to 250 ° C.

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