JP7005709B2 - Substrates for manufacturing dispersions and printed wiring boards - Google Patents

Description

The present invention relates to dispersions. The present invention also relates to a substrate for manufacturing a printed wiring board having a film formed by using the dispersion of the present invention.

The circuit board has a structure in which conductive wiring is provided on the substrate. A conventional method for manufacturing such a circuit board is generally to apply a photoresist on a substrate to which a metal foil is bonded, and to expose and develop the photoresist to obtain a negative shape of a desired circuit pattern. , And removing the metal leaf of the portion not coated with the photoresist by chemical etching to form a pattern. The conventional method for manufacturing a circuit board can manufacture a high-performance conductive board. However, the conventional method for manufacturing a circuit board has drawbacks such as a large number of steps, complexity, and the need for a photoresist material.

On the other hand, a method including directly printing a desired wiring pattern on a substrate by using a dispersion in which particles containing a metal and a metal oxide are dispersed (hereinafter, also referred to as “conductive paste”) is attracting attention. Has been done. Such a method of directly printing a desired wiring pattern on a substrate has extremely high productivity because the number of steps is small and it is not necessary to use a photoresist material.

However, the commonly used conductive paste uses silver fine particles as particles containing a metal and a metal oxide, and silver is very expensive, so that there is a cost merit brought about by the productivity improvement by the direct printing method. It will be offset. In addition, it is known that silver is easy to migrate, and wiring using silver paste is unreliable.

To solve these problems, many conductive pastes using copper fine particles have been studied.

For example, Patent Document 1 discloses a copper paste containing copper powder, lead-free glass frit, copper oxide, a resin binder and a thixo agent.

Patent Document 2 discloses a dispersion containing copper nanoparticles and ethyl cellulose. By using copper nanoparticles having a particle diameter of about 100 nm, firing can be performed at 500 ° C.

Japanese Unexamined Patent Publication No. 2012-54113 Japanese Unexamined Patent Publication No. 2012-52240

However, in the method described in Cited Document 1, since particles having a large particle size are used, a high temperature of 900 ° C. is required for firing. Further, in the method described in Cited Document 2, although the firing temperature is 500 ° C., the resin base material cannot be used at 500 ° C., so there is room for further lowering the temperature. In addition, the copper nanoparticles are easily oxidized, and the dispersibility of the nanoparticles deteriorates due to the oxidation and aggregation proceeds, so that the dispersion cannot be stored for a long period of time.

Therefore, the problem to be solved by the present invention is to obtain a dispersion capable of forming low resistance wiring on a low heat resistant resin substrate and a substrate for manufacturing a printed wiring board having a film formed by using the dispersion. To provide.

The present inventors have conducted extensive research and experiments in order to achieve the above-mentioned problems. As a result, it was found that the above-mentioned problems can be achieved by using a dispersion containing particles containing a metal or a metal oxide and a non-volatile organic substance containing a specific amount of nitrogen, and the present invention is based on this. Is completed.

That is, the present invention is as follows.
[1]
With particles containing metals and / or metal oxides,
A dispersion containing a non-volatile organic substance,
The primary particle diameter of the particles is 5 nm or more and less than 100 nm.
The non-volatile organic substance contains a nitrogen-containing organic substance, and the nitrogen content of the non-volatile organic substance is 6% by mass or more and 55% by mass or less.
[2]
The nitrogen-containing organic substance has at least one selected from a nitrate ester structure, a nitro group, a cyano group, and a heterocyclic structure containing nitrogen.
The dispersion according to item 1.
[3]
The nitrogen-containing organic substance has an aldose structure.
The dispersion according to item 1 or 2.
[4]
The particles include particles composed of copper oxide,
The dispersion according to item 1.
[5]
A substrate for manufacturing a printed wiring board having a substrate and a film formed on the substrate, wherein the film is
With particles containing metals and / or metal oxides,
Contains non-volatile organic matter,
The primary particle diameter of the particles is 5 nm or more and less than 100 nm.
The non-volatile organic substance contains a nitrogen-containing organic substance, and the nitrogen content of the non-volatile organic substance is 6% by mass or more and 55% by mass or less, a substrate for manufacturing a printed wiring board.

According to the present invention, it is possible to obtain a dispersion capable of forming low resistance wiring on a low heat resistant resin substrate and a substrate for manufacturing a printed wiring board having a film formed by using the dispersion.

Hereinafter, the present invention will be described in detail for the purpose of exemplifying an embodiment of the present invention (hereinafter referred to as “the present embodiment”), but the present invention is not limited to the present embodiment. In the present specification, the upper limit value and the lower limit value of each numerical range can be arbitrarily combined.

《Dispersion》
The dispersion of the present embodiment contains particles containing a metal and / or a metal oxide and a non-volatile organic substance, the primary particle diameter of the particles is 5 nm or more and less than 100 nm, and the nitrogen content of the non-volatile organic substance. Is 6% by mass or more and 55% by mass or less.

[particle]
The particles in the dispersion of the present embodiment are particles containing a metal and a metal oxide. As the metal and the metal oxide, at least one selected from the group consisting of gold, silver, copper, nickel, cobalt, tin, lead, indium, aluminum, zirconium, cerium, hafnium, and magnesium, and oxides of these metals. It may be one. Copper and copper oxide are preferable because they are inexpensive and can form wiring with low resistance by firing. Specific examples of the particles containing copper and copper oxide may be, for example, particles composed of copper, cuprous oxide, cupric oxide, and other copper oxide having an oxidation number, and may be a core portion. It may be a particle having a core / shell structure in which copper is copper and the shell portion is copper oxide. As copper oxide, cuprous oxide and cupric oxide are preferable because they tend to have excellent dispersibility and are chemically stable, and cuprous oxide is particularly preferable because they tend to be easily sintered at low temperature. The particles containing a metal and a metal oxide may contain a metal salt, a metal complex, or both as a small amount of impurities. As the particles containing a metal and a metal oxide, one kind may be used alone, or a plurality of kinds may be used in combination.

The average secondary particle size of the particles contained in the dispersion of the present embodiment is not particularly limited, but is preferably 1,000 nm or less, more preferably 500 nm or less, still more preferably 200 nm or less, and particularly preferably 80 nm or less. The average secondary particle size of the particles is preferably 5 nm or more, more preferably 15 nm or more, still more preferably 20 nm or more. The average secondary particle size is the average particle size of agglomerates (secondary particles) formed by aggregating a plurality of primary particles. When the average secondary particle size is 1,000 nm or less, it tends to be easily fired at a low temperature, which is preferable. When the average secondary particle size is 5 nm or more, the long-term storage stability of the dispersion is improved, which is preferable. The average secondary particle size of the particles can be measured by the cumulant method using, for example, FPAR-1000 manufactured by Otsuka Electronics Co., Ltd.

The average primary particle size of the primary particles constituting the secondary particles is preferably less than 100 nm, more preferably less than 50 nm, still more preferably less than 20 nm. The average primary particle size is preferably 1 nm or more, more preferably 2 nm or more, still more preferably 5 nm or more. When the average primary particle size is 100 nm or less, the firing temperature described later tends to be lowered, and the smaller the average primary particle size, the lower the firing temperature, which is preferable. It is considered that the reason why such low-temperature firing is possible is that the smaller the particle size of the particles, the larger the surface energy and the lower the melting point. Further, when the average primary particle size is 1 nm or more, good dispersibility can be obtained, which is preferable. The average primary particle size can be measured by a transmission electron microscope or a scanning electron microscope.

The content of the particles in the dispersion of the present embodiment is preferably 0.50% by mass or more and 70% by mass or less, more preferably 1.0 to 60% by mass, and further, with respect to the total mass of the dispersion. It is preferably 5.0 to 50% by mass. When this content is 70% by mass or less, it tends to be easy to suppress the aggregation of particles. When the content is 0.50% by mass or more, the conductive film obtained by firing does not become excessively thin, and the conductivity tends to be good, which is preferable.

As the particles in this embodiment, a commercially available product or a synthetic product may be used. Examples of commercially available products include cupric oxide particles manufactured by CIK Nanotech having an average primary particle size of 50 nm.

Examples of the particle synthesis method include the following methods.
(1) Water and a copper acetylacetonato complex are added to the polyol solvent, the organic copper compound is once heated and dissolved, an amount of water required for the reaction is further added, and the mixture is heated to the reduction temperature of the organic copper for reduction. Method.
(2) A method of heating an organic copper compound (copper-N-nitrosophenylhydroxylamine complex) at a high temperature of about 300 ° C. in an inert atmosphere in the presence of a protective agent such as hexadecylamine.
(3) A method of reducing a copper salt dissolved in an aqueous solution with hydrazine.

The method (1) above can be performed under the conditions described in, for example, Angewandte Chemie International Edition, No. 40, Volume 2, p.359, 2001.

The method (2) above may be described, for example, in the Journal of American Chemical Society, 1999, Vol. 121, p. It can be carried out under the conditions described in 11595.

In the method (3) above, a divalent copper salt can be preferably used as the copper salt, and examples thereof include copper (II) acetate, copper (II) nitrate, and copper (II) carbonate. Examples thereof include copper (II) chloride and copper (II) sulfate. The amount of hydrazine used is preferably 0.2 mol to 2 mol, more preferably 0.25 mol to 1.5 mol, with respect to 1 mol of the copper salt.

A water-soluble organic compound may be added to the aqueous solution in which the copper salt is dissolved. By adding a water-soluble organic compound to the aqueous solution, the melting point of the aqueous solution is lowered, so that reduction at a lower temperature is possible. As the water-soluble organic compound, for example, alcohol, a water-soluble polymer and the like can be used.

As the alcohol, for example, methanol, ethanol, propanol, butanol, hexanol, octanol, decanol, ethylene glycol, propylene glycol, glycerin and the like can be used. As the water-soluble polymer, for example, polyethylene glycol, polypropylene glycol, polyethylene glycol-polypropylene glycol copolymer and the like can be used.

The temperature at the time of reduction in the method (3) above can be, for example, −20 to 60 ° C., preferably −10 to 30 ° C. This reduction temperature may be constant during the reaction, or may be raised or lowered during the reaction. In the initial stage of the reaction in which the activity of hydrazine is high, the reduction is preferably performed at 10 ° C. or lower, and more preferably at 0 ° C. or lower. The reduction time is preferably 30 minutes to 300 minutes, more preferably 90 minutes to 200 minutes. The atmosphere during reduction is preferably an inert atmosphere such as nitrogen or argon.

Among the methods (1) to (3) above, the method (3) is preferable because it is easy to operate and particles having a small particle size can be obtained.

[Non-volatile organic matter]
The dispersion of the present embodiment contains a non-volatile organic substance for the purpose of improving printability, long-term storage stability, and lowering the firing temperature.

The non-volatile organic substance in the present embodiment may be a single compound or a mixture of a plurality of compounds. Here, the non-volatile organic substance refers to an organic component that remains on the substrate after the dispersion is applied onto the substrate and dried at 100 ° C. for 30 minutes.

The non-volatile organic substance in the present embodiment contains a nitrogen-containing organic substance, and the nitrogen content of the non-volatile organic substance is 6% by mass or more and 55% by mass or less. The nitrogen content of the non-volatile organic substance is preferably 7.5% by mass or more, more preferably 10% by mass or more, preferably 21% by mass or less, and more preferably 13% by mass or less. If the nitrogen content is 6% by mass or more, the dispersibility of the particles is improved, and if it is 7.5% by mass or more, the organic matter is decomposed at a lower temperature, so that firing at a lower temperature becomes possible, and if it is 10% by mass or more. If there is, the residue after firing is less likely to remain, so that the obtained conductive film has a lower resistance. When the nitrogen content is 55% by mass or less, the chemical stability is excellent and long-term storage is excellent, and when the nitrogen content is 50% by mass or less, the chemical stability is more excellent and long-term storage is possible. As used herein, the nitrogen content refers to the mass% of nitrogen contained in the non-volatile organic matter. Nitrogen content can be measured by elemental analysis.

The non-volatile organic substance in the present embodiment includes an organic substance having a structure containing nitrogen (also referred to as “nitrogen-containing organic substance” in the present specification). Examples of the nitrogen-containing structure include a nitrogen-containing functional group, a nitrogen-containing bond, a nitrogen-containing heterocyclic structure, and a nitrogen-containing other structure.

Specific examples of the functional group containing nitrogen include an amino group, a nitro group, a nitroso group, a cyano group, an isocyanate group, an azido group, an isocyano group and the like. Organic substances having at least one group selected from a nitro group, a cyano group, and an amino group are preferable because they improve the dispersibility of the particles. In particular, organic substances having a nitro group and / or a cyano group are preferable because they have a low decomposition temperature and tend to be calcined at a low temperature.

Specific examples of the bond containing nitrogen include an imide bond, an amide bond, a urethane bond, an ionic bond, a hydrogen bond, and a coordination bond. In particular, organic substances having an amide bond and / or a urethane bond are preferable because they are easily decomposed and tend to be calcined at a low temperature.

Specific examples of the nitrogen-containing heterocyclic structure include ethyleneimine, azirin, azacyclobutane, azeto, 2-pyrrolidone, pyrrolidine, pyrrole, piperidine, pyridine, pyrimidine, pyridazine, pyrazine, triazine, hexamethyleneimine, and azatropylidene. Imidazole, pyrazole, oxazole, isoxazole, thiazole, isothiazole, imidazoline, pyrazine, morpholine, thiadine, indole, isoindole, benzimidazole, purine, quinoline, isoquinoline, quinazoline, quinoxalin, phthalazine, cinnoline, pteridine, 1,4- Examples thereof include benzdiazepine, aclysine, phenoxazine, phenothiazine, carbazole, phenanthrolin, porphyrin, chlorin, choline, benzo-c-cinnoline, piperazine, quinuclidine, azetidine-2-one, and tropane.

Specific examples of other structures containing nitrogen include enamine, imine, oxime, lactam, lactim, amidine, nitrone, nitrate ester and the like. An organic substance having a lactam structure is preferable because the dispersibility of particles is improved, and a γ-lactam structure is particularly preferable. Organic substances having a nitrate ester structure are preferable because they are easily decomposed and the conductive film after firing tends to have a low resistance.

The structure containing nitrogen can be specified by an ultraviolet-visible absorption spectrum method, an infrared absorption spectrum method, a Raman spectrum method, a nuclear magnetic resonance method, an electron spin resonance method, a mass spectrometry method, an X-ray analysis method, or the like. ..

The non-volatile organic substance of the present embodiment may have, for example, the following structure in addition to the structure containing nitrogen. That is, the non-volatile organic substances are polyethylene glycol (PEG), polypropylene glycol (PPG), polyimide, polyethylene terephthalate (PET), polyethersulfone (PES), polyethylene naphthalate (PEN), polyester, polycarbonate (PC), polyvinyl. Alcohol (PVA), polyvinyl butyral (PVB), polyacetal, polyallylate (PAR), polyamide (PA), polyamideimide (PAI), polyetherimide (PEI), polyphenylene ether (PPE), polyphenylene sulfide (PPS), poly Etherketone (PEK), polyphthalamide (PPA), polyethernitrile (PEN), polybenzimidazole (PBI), polycarbodiimide, polysiloxane, polymethacrylicamide, nitrile rubber, acrylic rubber, polyethylene tetrafluoride, epoxy resin , Phenol resin, melamine resin, urea resin, polymethylmethacrylate resin (PMMA), polybutene, polypentene, ethylene-propylene copolymer, ethylene-butene-diene copolymer, polybutadiene, polyisoprene, ethylene-propylene-diene Polymer, butyl rubber, polymethylpentene (PMP), polystyrene (PS), styrene-butadiene copolymer, polyethylene (PE), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polyetheretherketone (PEEK) , Phenol novolak, benzocyclobutene, polyvinylphenol, polychloropyrene, polyoxymethylene, polysulfone (PSF), polysulfide, silicone resin, aldose, cellulose, amylose, purulan, dextrin, glucan, fructan, and chitin. Can be done. The non-volatile organic substance may have a structure in which the functional groups of these structures are modified, a structure in which these structures are modified, or a copolymer structure having these structures. Organic substances having a skeleton selected from the group consisting of polyethylene glycol structure, polypropylene glycol structure, polyacetal structure, polybutene structure, and polysulfide structure are preferable because they are easily decomposed and hardly leave a residue in the conductive film obtained after firing. Organic substances having a structure selected from the group consisting of a cellulose structure, an amylose structure, a pullulan structure, a dextrin structure, a glucan structure, a fructan structure, and a chitin structure are preferable because they tend to have excellent particle dispersibility. In particular, organic substances having a cellulose structure and a pullulan structure can be suitably used because they are easily available.

The phosphorus content of the non-volatile organic substance of the present embodiment is preferably 5% by mass or less, more preferably 1% by mass or less, further preferably 0.5% by mass or less, and 0.0001. It is preferably 0% by mass or more, more preferably 0.001% by mass or more, and further preferably 0.005% by mass or more. When the phosphorus content of the non-volatile organic substance is 5% by mass or less, the metal is less likely to be corroded by phosphorus and the conductivity is less likely to decrease. When the phosphorus content is 0.0001% by mass or more, the affinity between the non-volatile organic substance and the metal is improved, and the dispersibility of the particles is improved.

It is preferable that the weight average molecular weight of the non-volatile organic substance is appropriately selected depending on the method of applying the dispersion to the substrate. When the dispersion is used for reverse printing, the weight average molecular weight of the non-volatile organic substance is preferably 500 or more, more preferably 800 or more, still more preferably 1,000 or more; 40,000 or less. It is preferably 20,000 or less, more preferably 5,000 or less, and even more preferably 5,000 or less. When the dispersion is used for screen printing, it is preferably 1,000 or more, more preferably 10,000 or more, further preferably 50,000 or more, and 1,000,000 or less. It is preferably 500,000 or less, more preferably 100,000 or less, and even more preferably 100,000 or less. When the dispersion is used for offset printing, it is preferably 500 or more, more preferably 1,000 or more, further preferably 5,000 or more, and preferably 100,000 or less. It is more preferably 50,000 or less, and even more preferably 20,000 or less. When the dispersion is used for letterpress printing, it is preferably 500 or more, more preferably 800 or more, further preferably 3,000 or more, preferably 1,000,000 or less, and 100. It is more preferably 000 or less, and even more preferably 10,000 or less.

The weight average molecular weight of the non-volatile organic matter can be measured by various mass spectrometry methods (MS) for low molecular weight compounds. On the other hand, high molecular weight compounds can be measured by gel permeation chromatography (GPC). As a guideline for low molecular weight, the molecular weight is less than 200, and as a guideline for high molecular weight, the molecular weight is 100 or more.

When the organic substance is hydrophilic, the GPC measurement conditions are as follows, for example.
Data processing: Tosoh EcoSEC-WS
Pump: Waters Accessy H
RI detector: Tosoh RI8020
Oven: Tosoh CO8020
Column: TSKgel G3000PWXI + G2500PWXI (7.8mm ID x 30cm)
Column temperature: 40 ° C
Eluent: pH = 3.5 aqueous phosphoric acid flow rate: 1.0 ml / min
Injection volume: 50 μl
Standard sample: Polyethylene oxide (Aldrich, PRODUCT No. 02393)

When the organic substance is hydrophobic, for example, it is as follows.
Data processing: Tosoh EcoSEC-WS
Equipment: Tosoh EcoSEC
Column: TSKgel SuperHZM-M (4.6 mm ID x 15 cm) + TSKgel SuperHZ2000 (4.6 mm ID x 15 cm)
Temperature: 40 ° C
Eluent: THF
Flow velocity: 0.35 ml / min
Detector: RI
Standard data: Polystyrene (Agilent easy cal)

The amount of the non-volatile organic substance added is preferably 0.1 part by mass or more, more preferably 5 parts by mass or more, still more preferably 10 parts by mass or more, and 50 parts by mass with respect to 100 parts by mass of the particles. It is preferably less than or equal to, more preferably 40 parts by mass or less, and further preferably 30 parts by mass or less. If the amount of the non-volatile organic substance added is 0.1 parts by mass or more, the film forming property is excellent, if it is 5 parts by mass or more, the dispersibility of the particles tends to be excellent, and if it is 10 parts by mass or more, the printability is excellent. There is a tendency. If it is 50 parts by mass or less, it is easy to obtain a conductive film by firing.

In the present embodiment, the non-volatile organic substance includes an organic substance having a structure containing nitrogen (also referred to as “nitrogen-containing organic substance” in the present specification).

The nitrogen-containing organic material preferably has at least one selected from a nitrate ester structure, a nitro group, a cyano group, and a heterocyclic structure containing nitrogen. The nitrogen-containing organic matter preferably has an aldose structure.

In the present embodiment, as the nitrogen-containing organic substance, specifically, at least one compound selected from the group consisting of nitrocellulose, polyvinylpyrrolidone, and cyanoethyl pullulan can be preferably used. In particular, nitrocellulose is preferable because it is excellent in particle dispersibility and low resistance of the conductive film after firing. The chemical structure of nitrocellulose is shown below.

The nitrogen content of nitrocellulose is preferably 6% by mass or more, more preferably 9% by mass or more, further preferably 11% by mass or more, preferably 13% by mass or less, and preferably 12.5% by mass or less. More preferred. When the nitrogen content of nitrocellulose is 6% by mass or more, the dispersibility of the particles is improved, and when it is 9% by mass or more, the organic matter is decomposed at a low temperature, so that low-temperature firing is possible, and when it is 11% by mass or more. Since the residue is less likely to remain, the resistance of the conductive film after firing is further reduced. If it is 13% by mass or less, it can be handled safely, and if it is 12.5% by mass or less, it is easily dissolved in a solvent.

The weight average molecular weight of the nitrogen-containing organic substance is not particularly limited, but is preferably 500 or more, more preferably 1,000 or more, still more preferably 2,000 or more; 1,000,000 or less. It is preferably 500,000 or less, more preferably 20,000 or less, and even more preferably 20,000 or less. If the weight average molecular weight is 500 or more, the dispersibility of the particles is improved, if it is 1,000 or more, the long-term storage stability is improved, and if it is 2,000 or more, the particles tend to have thixotropic properties and the printability is improved. do. If the weight average molecular weight is 1,000,000 or less, sufficient solubility can be obtained, if it is 500,000 or less, printable fluidity can be obtained, and if it is 20,000 or less, the particles can be obtained. Kneading becomes easier.

The ratio of the nitrogen-containing organic substance in the non-volatile organic substance is preferably 50% by mass or more, preferably 60% by mass or more, further preferably 70% by mass or more, and even 100% by mass. good. When the ratio of the nitrogen-containing organic substance in the non-volatile organic substance is 50% by mass or more, it tends to be calcined at a low temperature, which is preferable.

The dispersion of the present embodiment contains a non-volatile organic substance including a nitrogen-containing organic substance as an essential component. However, the dispersion of the present embodiment may further contain other components in addition to these. Examples of such other components include surface energy modifiers, dispersants, plasticizers, solvents and the like.

[Surface energy regulator]
The dispersion of the present embodiment may contain a surface energy adjusting agent in order to improve the coatability. This improves the smoothness of the resulting coating film when the dispersion is applied, thus resulting in a more uniform conductive film.

Specific examples of the surface energy adjusting agent include, as trade names, for example, Triton X-45, Triton X-100, Triton X, Triton A-20, Triton X-15, Triton X-114, Triton X-405, Tween. # 20, Tween # 40, Tween # 60, Tween # 80, Tween # 85, Pluronic F-68, Pluronic F-127, Span 20, Span 40, Span 60, Span 80, Span 83, Span 85, etc.; Chemical "Surflon S-221", "Surflon S-221", "Surflon S-231", "Surflon S-232", "Surflon S-233", "Surflon S-242", "Surflon S-243" , "Surflon S-611", etc .; "NovecFC-4430", "NovecFC-4432", etc. manufactured by 3M; "Megafuck F-444", "Megafuck F-558" manufactured by DIC, etc. may be mentioned. Among the surface energy modifiers, fluorine-containing surfactants are particularly preferable, and AGC Seimi Chemical's "Surflon S-221", "Surflon S-221", "Surflon S-231", "Surflon S-232", and "Surflon" are particularly preferable. "S-233", "Surfron S-242", "Surfron S-243", and "Surfron S-611"; 3M's "NovecFC-4430" and "NovecFC-4432"; and DIC's "Megafuck F". "-444" and "Megafuck F-558" are preferably used. These may be used alone or in combination of two or more.

The content of the surface energy adjusting agent in the dispersion of the present embodiment is not particularly limited, but is preferably 0.010% by mass or more, more preferably 0.10% by mass, based on the total mass of the dispersion. be. The content of the surface energy adjusting agent is preferably 2.0% by mass or less, more preferably 1.5% by mass or less, based on the total mass of the dispersion. When the dispersion pair contains 0.010% by mass or more of the surface energy adjusting agent, the film thickness of the obtained coating film becomes uniform when the dispersion is applied, and there is a tendency that coating unevenness is unlikely to occur. On the other hand, in the conductive film obtained by firing the coating film, the amount of the surface energy adjusting agent added is 2.0% by mass or less from the viewpoint of reducing the residue derived from the surface energy adjusting agent and obtaining good conductivity. Is preferable.

[Dispersant]
The dispersant has a function of improving the dispersibility of the particles and preventing the particles from coagulating and settling. Therefore, the dispersant improves the storage stability of the dispersion and the smoothness and film thickness uniformity of the coating film when the dispersion is applied.

As the dispersant, various commercially available dispersants can be used. Specific examples of the dispersant when the solvent is water or a highly polar solvent include DISPERBYK-102, DISPERBYK-187, DISPERBYK-190, DISPERBYK-191, DISPERBYK-193, DISPERBYK-194N, DISPERBYK-199 manufactured by Big Chemie. , DISPERBYK-2010, DISPERBYK-2012, DISPERBYK-2013, DISPERBYK-2015, DISPERBYK-2055, DISPERBYK-2060, DISPERBYK-2061, DISPERBYK-2096 and the like.

Specific examples of the dispersant when the solvent is a solvent system include DISPERBYK-102, DISPERBYK-103, DISPERBYK-109, DISPERBYK-110, DISPERBYK-111, DISPERBYK-118, DISPERBYK-140, DISPERBYK-145, DISPERBYK-. 168, DISPERBYK-180, DISPERBYK-182, DISPERBYK-2000, DISPERBYK-2001, DISPERBYK-2009, DISPERBYK-2022, DISPERBYK-2025, DISPERBYK-2050, DISPERBYK-2055, DISPERBYK-2055, DISPERBYK-2 DISPERBYK-2200, BYK-405, BYK-607, BYK-9076, BYK-9077, and Plysurf M208F and Plysurf DBS manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. can be mentioned.

Specific examples of the dispersant when no solvent is used include DISPERBYK-102, DISPERBYK-106, DISPERBYK-109, DISPERBYK-111, DISPERBYK-145, DISPERBYK-180, DISPERBYK-2008, DISPERBYK-2013, DISPERBYK-20. , DISPERBYK-2096, DISPERBYK-2152, DISPERBYK-2155, DISPERBYK-2200, BYK-9076, BYK-9077, BYK-P105 and the like.

The content of the dispersant in the dispersion is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, still more preferably 2% by mass or more, and 20% by mass or less, based on the total mass of the dispersion. Is preferable, 15% by mass or less is more preferable, and 10% by mass or less is further preferable.
The content of the dispersant is preferably 0.1% by mass or more, more preferably 2% by mass or more, further preferably 10% by mass or more, preferably 50% by mass or less, and 40% by mass, based on the total mass of the particles. It is more preferably mass% or less, and further preferably 30 mass% or less. If the content of the dispersant with respect to the total mass of the particles is 0.1% by mass or more, sedimentation of the particles can be effectively prevented, and if it is 2% by mass or more, good dispersibility can be obtained. If it is 10% by mass or more, good long-term storage stability can be obtained. When the content of the dispersant with respect to the total mass of the particles is 50% by mass or less, it is easy to obtain a conductive film by firing the coating film.

[Plasticizer]
The plasticizer can be added for the purpose of adjusting the viscosity and the drying rate of the dispersion. Therefore, the printability of the dispersion can be improved. The plasticizer is not particularly limited, but a plasticizer having excellent compatibility with other organic substances is preferable. As the plasticizer, fatty acid esters such as phthalates, phosphates, trimellitic acids and adipates, polyesters, epoxys, sulfonic acid amides and the like can be used. Specific examples of the plasticizer include triethyl citrate, acetyltriethyl citrate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diaryl phthalate, octyl phthalate, di-2-methoxyethyl phthalate, and phthalic acid. Bis (2-ethylhexyl), diisononyl phthalate, diundecyl phthalate, diamil phthalate, dimethyl tartrate, diethyl tartrate, dibutyl tartrate, dioctyl tartrate, dimethyl adipate, diethyl adipate, dioctyl adipate, dimethyl sebacate, diethyl sebacate , Dibutyl sebacate, di-2-methoxyethyl sebacate, dioctyl sebacate, dimethyl maleate, diethyl maleate, dibutyl maleate, dioctyl maleate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol dioctyl ether, O -Ethyl benzoyl benzoate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, N-ethyltoluene sulfonic acid amide, triacetin, p-toluene sulfonic acid O-cresyl, triethyl phosphate, triphenyl phosphate, tripropionin, Examples thereof include sebacic acid, hydride sebacic acid, polyethylene glycol-modified sebacic acid, and polyethylene glycol.

The content of the plasticizer in the dispersion is preferably 1% by mass or more, more preferably 10% by mass or more, further preferably 20% by mass or more, and preferably 60% by mass or less, preferably 40% by mass, based on the mass of the non-volatile organic substance. % Or less is more preferable, and 30% by mass or less is further preferable.

[solvent]
In addition to the non-volatile organic substance, the dispersion of the present embodiment may contain a solvent from the viewpoint of adjusting the viscosity and improving the coatability.

As the solvent in the dispersion of the present embodiment, various solvents can be used depending on the use of the dispersion. For example, it is preferable to use a high boiling point solvent in applications that require high smoothness, and it is preferable to use a low boiling point solvent in applications that require quick drying.

The vapor pressure of the low boiling point solvent at 20 ° C. is preferably 20 Pa or more and 150 hPa or less, more preferably 100 Pa or more and 100 hPa or less, and further preferably 300 Pa or more and 20 hPa or less. The vapor pressure is preferably 150 hPa or less in order to ensure the dispersion stability of the particles in the dispersion while maintaining a high volatilization rate of the solvent. On the other hand, the vapor pressure is preferably 20 Pa or more in order to achieve a drying rate that does not cause cracks in the dispersion coating film.

Specific examples of the low boiling solvent include water, ethyl acetate, normal propyl acetate, isopropyl acetate, pentanol, hexane, cyclohexane, methylcyclohexane, toluene, methylethylketone, methylisobutylketone, dimethylcarbonate, methanol, ethanol, and n. -Propanol, i-propanol, n-butanol, i-butanol, sec-butanol, t-butanol, n-pentanol, i-pentanol, 2-methylbutanol, sec-pentanol, t-pentanol, 3- Methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, 3-heptanol, n-octanol, 2-ethylhexanol, sec-octanol, n-nonyl alcohol, 2, Examples thereof include 6-dimethyl-4-heptanol, n-decanol, phenol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, diacetone alcohol and the like. Since the printing resin plate or blanket can be extended in life without swelling, the solvent is preferably a hydrophilic solvent, and among them, a mixed solvent composed of water and a monoalcohol having 10 or less carbon atoms is used. More preferred. Of the monoalcohols having 10 or less carbon atoms, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, sec-butanol, and t are particularly suitable because of their dispersibility, volatileness, and viscosity. -At least one selected from the group consisting of butanol is further preferred. These monoalcohols may be used alone or in combination of two or more. When the number of carbon atoms of the monoalcohol is 10 or less, the dispersibility of the particles is better.

The vapor pressure of the high boiling point solvent at 20 ° C. is preferably 0.010 Pa or more and less than 20 Pa, more preferably 0.05 Pa or more and less than 16 Pa, and further preferably 0.1 Pa or more and less than 14 Pa. The vapor pressure is preferably less than 20 Pa in order to maintain the smoothness of the dispersion coating film by the leveling effect. On the other hand, the vapor can be easily removed by a firing treatment described later, and in order to prevent the solvent residue that could not be completely removed from being mixed in the obtained conductive film and deteriorating its conductivity, the steam is used. The pressure is preferably 0.010 Pa or more.

Specific examples of the high boiling solvent include propylene glycol monomethyl ether acetate, 3methoxy-3-methyl-butyl acetate, ethoxyethyl propionate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and propylene glycol monopropyl. Ether, Propylene Glycol Terriary Buty Ether, Dipropylene Glycol Monomethyl Ether, Ethylene Glycol Butyl Ether, Ethylene Glycol Ethyl Ether, Ethylene Glycol Methyl Ether, Xylene, Mesitylene, Ethylbenzene, Octane, Nonan, Decane, Ethylene Glycol, 1,2-Propylene Glycol, 1,3-butylene glycol, 2-pentanediol, 2-methylpentane-2,4-diol, 2,5-hexanediol, 2,4-heptandiol, 2-ethylhexane-1,3-diol, diethylene glycol, Examples thereof include dipropylene glycol, hexanediol, octanediol, triethylene glycol, tri1,2-propylene glycol, glycerol and the like. Since the printing resin plate and the blanket do not swell and the life can be extended, the solvent is preferably a hydrophilic solvent, and a polyhydric alcohol having 10 or less carbon atoms is more preferable. These polyhydric alcohols may be used alone or in combination of two or more. When the number of carbon atoms of the polyhydric alcohol is 10 or less, the dispersibility of the particles is better.

The above-mentioned low boiling point solvent and high boiling point solvent may be mixed and used.

The amount of the solvent used is preferably 1% by mass or more and 99% by mass or less, and preferably 10% by mass or more and 95% by mass or less, based on the total mass of the dispersion. More preferably, it is selected according to the coating method.

For example, when the dispersion of the present embodiment is applied to inkjet printing, the content of the solvent is preferably 40% by mass or more, more preferably 60% by mass or more, based on the total mass of the dispersion. , 80% by mass or more, more preferably 99% by mass or less, further preferably 95% by mass or less, still more preferably 90% by mass or less. When the content of the solvent is 99% by mass or less, the film thickness of the coating film becomes sufficiently thick, and wiring having high conductivity can be formed by the firing treatment. When the content of the solvent is 40% by mass or more, the viscosity of the dispersant can be adjusted in a range suitable for inkjet printing, and when it is 80% by mass or more, the viscosity of the print head of the inkjet printing machine can be adjusted. Clogs are effectively prevented.

When the dispersion of the present embodiment is applied to screen printing, the content of the solvent is preferably 1% by mass or more, more preferably 10% by mass or more, and 20% by mass with respect to the total mass of the dispersion. % Or more, more preferably 60% by mass or less, more preferably 50% by mass or less, still more preferably 30% by mass or less.

When the dispersion of the present embodiment is applied to reverse printing, the content of the solvent is preferably 40% by mass or more, more preferably 50% by mass or more, and 70% by mass with respect to the total mass of the dispersion. % Or more, more preferably 95% by mass or less, more preferably 90% by mass or less, still more preferably 85% by mass or less.

<< Manufacturing method of dispersion >>
The dispersion can be prepared by mixing the above-mentioned particles, the non-volatile organic substance, and other components optionally blended in a predetermined ratio, and dispersing the particles. The dispersion treatment is performed by using an appropriate device such as an ultrasonic method, a mixer method, a three-roll method, a two-roll method, an attritor, a Banbury mixer, a paint shaker, a kneader, a homogenizer, a ball mill, and a sand mill. Can be done.

When preparing the dispersion of the present embodiment, the dispersion obtained by appropriately setting the concentrations of the above-mentioned particles and non-volatile organic substances, and optionally blended solvent, surface energy adjusting agent, and other components. The viscosity and surface energy of the body can be adjusted.

It is preferable that the viscosity of the dispersion of the present embodiment at 25 ° C. is appropriately selected depending on the intended use. When the dispersion is used for screen printing in a region where the shear rate measured using a cone-plate type rotational viscometer is 1 × 10 ^-1 s ^-1 to 1 × 10 ² s ^-1 , the temperature of the dispersion is 25 ° C. The viscosity in the above is preferably 1 cp or more, more preferably 10 cp or more, further preferably 100 cp or more, preferably 1,000,000 cp or less, and more preferably 100,000 cp or less. It is preferably 1,000 cp or less, and more preferably 1,000 cp or less. When the dispersion is used for gravure offset printing, the viscosity of the dispersion at 25 ° C. is preferably 1 cp or more, more preferably 10 cp or more, further preferably 100 cp or more, and 100,000 cp or less. Is preferable, and it is more preferably 10,000 cp or less, and further preferably 1,000 cp or less. When the dispersion is used for reverse printing, the viscosity of the dispersion at 25 ° C. is preferably 0.1 cp or more, more preferably 1 cp or more, further preferably 5 cp or more, and 1,000 cp or less. It is more preferable, it is more preferably 100 cp or less, and further preferably 50 cp or less. When the dispersion is used for letterpress printing, the viscosity of the dispersion at 25 ° C. is preferably 1 cp or more, more preferably 10 cp or more, further preferably 100 cp or more, and more preferably 100,000 cp or less. It is preferably 10,000 cp or less, more preferably 1,000 cp or less, and even more preferably 1,000 cp or less. If the viscosity is in the above range, the printability will be better.

The surface free energy of the dispersion of the present embodiment at 25 ° C. is not particularly limited, but is preferably 40 mN / m or less, more preferably 35 mN / m or less, and further preferably 30 mN / m or less. In reverse printing, the surface free energy of the dispersion at 25 ° C. is preferably 40 mN / m or less from the viewpoint of the wettability of the dispersion to the blanket. The surface free energy can be measured using a contact angle meter.

<< Substrates for manufacturing printed wiring boards and their manufacturing methods >>
The printed wiring board manufacturing substrate of the present embodiment has a substrate and a film formed on the substrate (hereinafter, also referred to as “coating film”). The film contains particles containing a metal and / or a metal oxide and a non-volatile organic substance, and the primary particle diameter of the particles is 5 nm or more and less than 100 nm, and the non-volatile organic substance contains a nitrogen-containing organic substance. The nitrogen content of the non-volatile organic substance is 6% by mass or more and 55% by mass or less. The printed wiring board manufacturing substrate of the present embodiment can be manufactured, for example, by applying (printing) the dispersion of the present embodiment on the substrate and drying it. By printing the dispersion of the present embodiment in a desired pattern, a printed wiring board having a desired conductive pattern can be manufactured by a subsequent firing process.

[Base material]
Examples of the base material include a resin base material, a glass base material, a silicon wafer, a paper base material, and the like, in addition to a general printed circuit board. Examples of a general printed circuit board include a paper phenol substrate, a paper epoxy substrate, a glass composite substrate, a glass epoxy substrate, a Teflon substrate, an alumina substrate, a low temperature co-fired ceramics (LTCC) substrate, and the like.

Examples of the resin base material include polyimide, polyethylene terephthalate (PET), polyether sulfone (PES), polyethylene naphthalate (PEN), polyester, polycarbonate (PC), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), and the like. Polyacetal, polyallylate (PAR), polyamide (PA), polyamideimide (PAI), polyetherimide (PEI), polyphenylene ether (PPE), polyphenylene sulfide (PPS), polyetherketone (PEK), polyphthalamide (PPA) ), Polyethernitrile (PEN), Polybenzimidazole (PBI), Polycarbodiimide, Polysiloxane, Polymethacrylate, Nitrile rubber, Acrylic rubber, Polyethylene tetrafluoride, Epoxy resin, Phenolic resin, Melamine resin, Urea resin, Poly Methyl methacrylate resin (PMMA), polybutene, polypentene, ethylene-propylene copolymer, ethylene-butene-diene copolymer, polybutadiene, polyisoprene, ethylene-propylene-diene copolymer, butyl rubber, polymethylpentene (PMP) , Polystyrene (PS), styrene-butadiene copolymer, polyethylene (PE), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polyetheretherketone (PEEK), phenol novolac, benzocyclobutene, polyvinylphenol, A substrate composed of polychloropyrene, polyoxymethylene, polysulfone (PSF), cycloolefin polymer (COP), silicone resin and the like can be used. In particular, PET and PEN are available at low cost, are significant from a business point of view, and are preferable.

The deflection temperature under load of the substrate is preferably 300 ° C. or lower, more preferably 275 ° C. or lower, and even more preferably 250 ° C. or lower. A substrate having a deflection temperature under load of 300 ° C. or less is available at low cost, is significant from a business point of view, and is preferable.

The thickness of the base material can be, for example, 1 μm to 10 mm, preferably 25 μm to 250 μm. When the thickness of the base material is 250 μm or less, the manufactured electronic device can be made lighter, space-saving, and flexible, which is preferable.

[Preparation of base material]
The substrate may be washed before forming the coating film. As a method for cleaning the substrate, for example, wet treatment using a chemical solution; dry treatment using corona discharge, plasma, UV, ozone, or the like can be used.

When the formed coating film contains a solvent, the solvent is preferably removed from the coating film. The removal of this solvent can be carried out by a method in which the film after coating is allowed to stand at, for example, 20 to 150 ° C. for, for example, 1 minute to 2 hours. As the heating method in this case, for example, hot air drying, infrared drying, vacuum drying and the like can be used.

[Coating film forming method]
The method for forming the coating film on the substrate as described above using the dispersion of the present embodiment is not particularly limited. For example, use methods such as screen printing, spray coating, spin coating, slit coating, die coating, bar coating, knife coating, offset printing, reverse printing, flexo printing, inkjet printing, dispenser printing, gravure direct printing, and gravure offset printing. Can be done. Of these methods, reverse printing is preferable from the viewpoint of being able to perform high-definition patterning.

(Reverse printing)
The dispersion of the present embodiment can be particularly preferably used for forming a patterned coating film on a substrate by reverse printing.

In the reverse printing method, first, a coating film having a uniform thickness is formed on the surface of the blanket.
The surface of the blanket is usually made of silicone rubber. In reverse printing, it is necessary that the dispersion adheres well to the silicone rubber to form a uniform coating film. Therefore, it is desirable that the viscosity of the dispersion of the present embodiment at 25 ° C. is 1 cp or more and 10,000 cp or less, and the surface free energy at 25 ° C. is 40 mN / m or less.

The surface of the blanket on which the uniform dispersion coating film was formed on the surface as described above was then brought into contact with the letterpress and pressed, and the coating film formed on the surface of the convex portion of the letterpress was formed on the surface of the blanket. A part is attached and transferred. As a result, a desired print pattern is formed on the coating film remaining on the surface of the blanket.

Then, the blanket in this state is pressed against the surface of the substrate to be printed, and the patterned coating film remaining on the blanket is transferred to form the patterned coating film on the substrate to be printed. can.

[Film thickness of coating film]
The film thickness of the coating film can be selected according to the coating method.
For example, when inkjet printing is used, the film thickness of the coating film is preferably 0.1 to 10 μm, more preferably 0.5 to 5 μm as the value after removing the solvent.

When screen printing is used, the coating film thickness value after removing the solvent is preferably 1 to 100 μm, more preferably 10 to 50 μm.

When reverse printing is used, the coating film thickness value after removing the solvent is preferably 0.01 to 5 μm, more preferably 0.1 to 1 μm.

The surface roughness (Ra) of the coating film is preferably 12 nm or less, more preferably 7 nm or less, and further preferably 4 nm or less. When Ra is 12 nm or less, the coating film tends to adhere to the removal plate during reverse printing, and sufficient removal property tends to be obtained. When Ra is 7 nm or less, a flat film surface tends to be maintained even in the obtained conductive film. When Ra is 4 nm or less, firing unevenness is very small, and uniform electrical characteristics tend to be obtained.

When the coating film formed as described above contains a solvent, the solvent is then preferably removed from the coating film. The removal of this solvent can be carried out by a method in which the film after coating is allowed to stand at, for example, 20 to 150 ° C. for, for example, 1 minute to 2 hours. As the heating method in this case, for example, hot air drying, infrared drying, vacuum drying and the like can be used.

[Coating film]
The coating film formed by coating the dispersion of the present embodiment contains particles containing a metal or a metal oxide and a non-volatile organic substance, and the non-volatile organic substance in the coating film contains a nitrogen-containing organic substance. The nitrogen content of the non-volatile organic matter is 6% by mass or more.

Among the components contained in the dispersion used for coating, this film preferably contains components other than the solvent while maintaining its chemical structure and composition ratio. Therefore, as for the constituent components of the membrane, those described above are preferably applied as they are as the constituent components of the dispersion.

The coating film of the present embodiment is preferably bendable, that is, flexible without impairing its function. The bendable radius of curvature is preferably 1,000 mm or less, more preferably 500 mm or less, and even more preferably 100 mm or less. If it is 1,000 mm or less, it can be attached to the human torso, if it is 500 mm or less, it can be attached to the human leg, and if it is 100 mm or less, it can be attached to the human upper limb. In addition, it becomes possible to apply a roll-to-roll manufacturing method. The lower limit of the radius of curvature can be, for example, 0.1 mm or more.

<< Printed wiring board and its manufacturing method >>
A conductive wiring having a conductive film can be formed by firing a substrate for manufacturing a printed wiring board having a coating film formed by the dispersion of the present embodiment.

[Baking]
By heating the coating film formed as described above and then performing a firing treatment, a conductive film can be formed on the substrate.

The firing method is not particularly limited as long as the particles contained in the coating film can be fused to form a sintered film of metal particles.

The firing may be performed by, for example, a method using a heat medium such as a firing furnace, or may be performed by using plasma, ultraviolet rays, vacuum ultraviolet rays, electron beam, infrared lamp annealing, flash lamp annealing, laser or the like. Of these, plasma treatment, flash lamp annealing treatment, or contact treatment with a heat medium is preferable.

In particular, the flash lamp annealing treatment and the plasma treatment have a feature that the inorganic substance is strongly heated but the organic substance is not heated so much. Therefore, heating by these methods heats only the particles and does not cause heat damage to the substrate. Therefore, an inexpensive but poorly heat-resistant resin such as PET can be used as the base material, which is preferable. In particular, plasma treatment is more preferable because only the surface of the inorganic substance tends to be heated and the damage to the base material due to heat transfer is small.

(Formation of conductive film by heat treatment)
Specifically, the heat treatment in the present embodiment is a treatment in which the sample is heated by contacting it with a high-temperature medium.

The high-temperature medium is not particularly specified, but for example, air, an inert gas, a reducing gas, a liquid, a metal, a ceramic, a resin, or the like can be used.

The heat source for heating the medium is not particularly specified, but for example, a far-infrared heater, a near-infrared heater, a resistance heating heater, a microwave heater, a combustion heating heater and the like can be used. As the far-infrared heater, for example, a halogen heater, a quartz tube heater, a carbon heater, a sheathed heater, a metal heater and the like can be used. As the near-infrared heater, for example, a halogen heater can be used. As the resistance heating heater, for example, a metal heater or a ceramic heater can be used. As the heating element of the metal heater, for example, an alloy such as an iron-chromium-aluminum alloy or a nickel-chromium alloy and a metal such as platinum, molybdenum, tantalum, or tungsten can be used. As the heating element of the ceramic heater, for example, silicon carbide, molybdenum-silicite, carbon or the like can be used. The microwave heater is a heater of a type that heats an object by an electromagnetic wave of about 100 kHz to 10 GHz. The combustion heater is a type of heater that heats an object by the heat of combustion when combustibles such as heavy oil and gas are burned.

The heat treatment temperature is preferably 180 ° C. or lower, more preferably 150 ° C. or lower, and even more preferably 120 ° C. or lower. When the heat treatment temperature is 180 ° C. or lower, a general-purpose resin substrate such as PEN or PET, which has low heat resistance but is inexpensive, can be used. The heat treatment temperature is preferably 20 ° C. or higher, more preferably 30 ° C. or higher, and even more preferably 50 ° C. or higher. If the temperature is 20 degrees or higher, the particles move in the coating film due to thermal vibration, and the particles come into contact with each other to reduce the volume resistivity. At 30 ° C or higher, the softening of the organic matter in the coating film accelerates the movement of the particles in the coating film, and when the organic matter is further softened, the particles settle due to the difference in specific gravity between the particles and the organic matter, and the particle layer and the organic matter are formed. Since it is separated into layers and it becomes difficult for insulating organic substances to enter between the particles, the volume resistance can be further reduced. If the temperature is 50 ° C. or higher, the sintering of the particles proceeds, so that the volume resistance can be further reduced.

The heat treatment time is preferably 10 seconds or longer, more preferably 1 minute or longer, and even more preferably 10 minutes or longer. If the heat treatment time is 10 seconds or more, the resistance of the fired film can be lowered by bringing the particles into contact with each other, and if the heat treatment time is 1 minute or more, the resistance of the particles themselves is lowered, so that the resistance of the fired film is further lowered. If it is 10 minutes or more, the resistance of the fired film can be further reduced by the progress of sintering of the particles. Further, the heating and firing time is preferably 4 hours or less from the viewpoint of reducing heat damage to the substrate.

The atmosphere during the heat treatment is not particularly specified, but it is preferably an inert atmosphere, and more preferably a reducing atmosphere. The atmosphere can be controlled, for example, by flowing an appropriate gas into the firing furnace. The inert atmosphere can be formed by flowing an inert gas. As the inert gas, a rare gas such as vacuum, nitrogen, argon, or helium can be used as an inert gas. The reducing atmosphere can be formed by flowing a reducing gas. Specifically, as the reducing gas, hydrogen, carbon monoxide, hydrogen sulfide, formaldehyde and the like can be used. Hydrogen is particularly preferable because it is not toxic. The inert gas and the reducing gas can be mixed to form a reducing atmosphere. For example, when the inert gas and hydrogen are mixed, the hydrogen content is preferably 0.1% by mass or more and 4% by mass or less. If the amount is less than 0.1% by mass, sufficient reducing property cannot be obtained, and if it is 4% by mass or less, it does not show flammability and can be used safely.

(Heating by infrared lamp annealing)
Specifically, infrared lamp annealing is a method of directly heating a sample by irradiating the sample with infrared rays.

Although the infrared source is not particularly specified, for example, a halogen heater, a quartz tube heater, a carbon heater, a sheathed heater, a metal heater and the like can be used.

The atmosphere at the time of infrared lamp annealing is not particularly specified, but it is preferably an inert atmosphere, and more preferably a reducing atmosphere. The atmosphere can be controlled, for example, by flowing an appropriate gas into the firing furnace. The inert atmosphere can be formed by flowing an inert gas. As the inert gas, a rare gas such as vacuum, nitrogen, argon, or helium can be used as an inert gas. The reducing atmosphere can be formed by flowing a reducing gas. Specifically, as the reducing gas, hydrogen, carbon monoxide, hydrogen sulfide, formaldehyde and the like can be used. Hydrogen is particularly preferable because it is not toxic. The inert gas and the reducing gas can be mixed to form a reducing atmosphere. For example, when the inert gas and hydrogen are mixed, the hydrogen content is preferably 0.1% by mass or more and 4% by mass or less. If the amount is less than 0.1% by mass, sufficient reducing property cannot be obtained, and if it is 4% by mass or less, it does not show flammability and can be used safely.

(Heating by plasma treatment)
Specifically, the plasma treatment is a treatment for exposing the sample to the plasma by generating plasma in the space where the sample is placed.

The method of generating plasma is not particularly specified, but for example, a method using DC arc discharge, high frequency electromagnetic field, microwave, or the like can be used. In particular, the method using microwaves is preferable because plasma can be generated at a low temperature and the heat damage to the substrate is small. Specifically, the microwave means an electromagnetic wave having a frequency of 300 MHz or more and 3 THz or less. The center frequency of the microwave is preferably 2 GHz or more and 4 GHz or less, and more preferably 2.4 GHz or more and 2.5 GHz or less.

The device for generating microwave plasma is composed of, for example, a microwave oscillator, a transmission circuit, an antenna, and a discharge container. In addition to these, a magnetic field generator may be further used if necessary. In this device, plasma is generated in the discharge vessel. As the microwave oscillator, for example, a klystron, a magnetron, a gyrotron or the like can be used. As the transmission circuit, for example, a rectangular waveguide, a circular waveguide, a coaxial line, or the like can be used. A power monitor and a dummy load that absorbs reflected power may be installed in the middle of the transmission circuit. As the structure of the apparatus, for example, it has a transmission line at the upper part and a discharge container at the lower part, the transmission line and the discharge container are connected to each other through a quartz window, and a sample table is placed at the lower part of the discharge container. It is preferable that it is installed.

The microwave output is not particularly specified, but it is preferably 100 W or more and 10 kW or less. The microwave output may be constant during processing or may be changed during processing.

The temperature of the sample table is not particularly specified, but it is preferably 30 ° C. or higher and 150 ° C. or lower. When this temperature is 150 ° C. or lower, a general-purpose resin substrate having low heat resistance such as PET can be used as the base material. If the temperature is 30 ° C. or higher, a dense conductive film can be obtained.

The ambient atmosphere during plasma treatment is not particularly specified, but a reducing atmosphere is preferable. The ambient atmosphere can be controlled, for example, by flowing an appropriate gas into the discharge vessel. Although the gas flow rate is not particularly specified, it is preferably 10 SCCM or more and 1,000 SCCM or less, more preferably 50 SCCM or more and 5,600 SCCM or less, and further preferably 100 SCCM or more and 400 SCCM or less. In particular, it is preferable to form a reducing atmosphere by flowing a mixed gas formed by mixing a small amount of hydrogen with the inert gas. As the inert gas in this mixed gas, for example, nitrogen; a rare gas such as helium or argon can be used. The content of hydrogen in the mixed gas is preferably 0.1% by mass or more and 10% by mass or less, and more preferably 2% by mass or more and 6% by mass or less.

The pressure in the discharge container may be atmospheric pressure or may be reduced.

Although the plasma treatment time is not particularly specified, it is preferably 10 seconds or more and 30 minutes or less, more preferably 30 seconds or more and 10 minutes or less, and further preferably 1 minute or more and 5 minutes or less.

(Heating by flash lamp annealing treatment)
The flash lamp annealing treatment is a treatment for heating a sample by irradiating the sample with light having a high energy density in a pulsed manner.

As the light source used for the flash lamp annealing treatment, for example, a xenon lamp, a krypton lamp, or the like can be used.

The wavelength of the light source is preferably in the visible light region because the coating film can be fired without causing heat damage to the transparent resin substrate. The wavelength of the light source can be easily controlled via a color filter.

The energy per pulse is not particularly specified, but is preferably 50 J or more and 3,000 J or less, more preferably 100 J or more and 2,000 J or less, and further preferably 150 J or more and 1,500 J or less. ..

Although the pulse time is not particularly specified, it is preferably 10 μs or more and 100 msec or less, more preferably 50 μs or more and 10 msec or less, and further preferably 100 μs or more and 5 msec or less. Here, the pulse time means the time from the time when the power is applied to the lamp for pulse light irradiation to the time when the power supply to the lamp is stopped due to the pulse light extinguishing.

The sample may be irradiated with pulsed light multiple times. The pulse interval is not particularly specified, but is preferably 10 μs or more and 1 second or less. Here, the pulse interval means the time from the time when the power is applied to the lamp for the irradiation of the pulse light to the time when the power is applied to the lamp for the irradiation of the next pulse light.

The temperature of the sample table is not particularly specified, but it is preferably 30 ° C. or higher and 150 ° C. or lower. When this temperature is 150 ° C. or lower, a general-purpose resin substrate having low heat resistance such as PET can be used as the base material. If the temperature is 30 ° C. or higher, a dense conductive film can be obtained.

At the time of flash lamp annealing treatment, gas may flow in the container. In this case, since the sample is cooled by the gas flow, the thermal damage of the base material can be reduced.

The ambient atmosphere during the flash lamp annealing treatment is not particularly specified, but a reducing atmosphere is preferable. Specific examples of this reducing atmosphere and gas flow rate are the same as those described above for the reducing atmosphere during plasma treatment.

After the flash lamp annealing treatment, a pressure treatment may be further performed. By pressurizing the sample after the flash lamp annealing treatment, the formed conductive film can be made denser, which is preferable. As the pressurizing method, for example, a roller press, a flat plate press, or the like can be used. A roller press is particularly preferable because it is suitable for a large area press.

[Advantages of Manufacturing Method of Printed Wiring Board Using Dispersion of This Embodiment]
The dispersion of the present embodiment can form a patterned coating film and a conductive film by directly drawing the dispersion of the present embodiment on a substrate in a desired pattern. Therefore, the productivity can be significantly improved as compared with the method using a conventional photoresist.

Further, by using the dispersion of the present embodiment, it is possible to easily produce a conductive film laminate having a diameter of 7 inches or more, which was difficult to produce by conventional photolithography.

[Conductive film]
The surface roughness (Ra) of the conductive film obtained by the above method is preferably 20 nm or less, more preferably 10 nm or less, still more preferably 5 nm or less. When Ra is 20 nm or less, there are few places where the film thickness is locally thin, and defects due to disconnection can be reduced. When Ra is 10 nm or less, defects tend to be less likely to occur when another film or element is further laminated on the conductive film. When Ra is 5 nm or less, the crystallinity of other materials further laminated on the conductive film can be improved, and therefore, for example, it can be suitably used for forming an electrode of a thin film transistor.

The resistivity of the conductive film of the present embodiment is preferably 200 μΩcm or less, more preferably 100 μΩcm or less, and further preferably 30 μΩcm or less.

The conductive film of the present embodiment is preferably bendable, that is, flexible without impairing its function. The bendable radius of curvature is preferably 1,000 mm or less, more preferably 500 mm or less, and even more preferably 100 mm or less. If it is 1,000 mm or less, it can be attached to the human torso, if it is 500 mm or less, it can be attached to the human leg, and if it is 100 mm or less, it can be attached to the human upper limb. In addition, it becomes possible to apply a roll-to-roll manufacturing method. The lower limit of the radius of curvature can be, for example, 0.1 mm or more.

<< Application example of the dispersion of this embodiment >>
According to the dispersion of the present embodiment, it is possible to obtain a highly smooth conductive film having a finely divided pattern. Such a conductive film can be suitably used for, for example, a printed circuit board, a flexible printed circuit board, an electromagnetic wave shielding sheet, a semiconductor device (thin film transistor, a diode, a ferroelectric memory, etc.), a metal mesh transparent conductive film, or the like.

A case where the dispersion of the present embodiment is applied to a metal mesh transparent conductive film will be described. The metal mesh transparent conductive film means a transparent substrate in which metal wiring having a width of 50 μm or less is formed in a mesh shape. This metal mesh transparent conductive film has a feature that the surface is electrically low resistance while being apparently transparent. Since it is difficult to visually recognize a structure having a width of 50 μm or less, it seems that the metal wiring of the metal mesh transparent conductive film does not exist on the substrate. Further, the region (opening) where the metal wiring does not exist transmits light. Therefore, the metal mesh transparent conductive film is visually recognized as a transparent body.

The dispersion of the present embodiment can be suitably used as a material for forming wiring in this metal mesh transparent conductive film.

When the dispersion of the present embodiment is applied to the wiring formation of the metal mesh transparent conductive film, the ratio of the area of the opening of the metal mesh transparent conductive film to the area of the entire surface of the conductive film is 50 area% or more. It is preferably 80 area% or more, more preferably 90 area% or more, and further preferably 90 area% or more. If this ratio is 50 area% or more, the metal mesh transparent conductive film is recognized as a transparent body; if it is 80 area% or more, the reflection of ambient light when the metal mesh transparent conductive film is used for a display. The amount is reduced, and the screen can be sufficiently recognized even outdoors; if the area is 90 area% or more, glare can be reduced when the metal mesh transparent conductive film is used for a display. The width of the wiring is preferably 50 μm or less, more preferably 10 μm or less, and further preferably 2 μm or less. If this width is 50 μm or less, the metal mesh transparent conductive film is recognized as a transparent body; if it is 10 μm or less, sufficient light transmittance and mesh density can be obtained for use in the transparent conductive film for a touch panel. Yes; if it is 2 μm or less, a highly uniform electric field can be formed on the mesh.

The dispersion of the present embodiment is suitably used for forming wiring of a metal mesh transparent conductive film in, for example, a common electrode of a liquid crystal display, an organic EL display, and an electronic paper; a light extraction electrode for organic EL lighting; and the like. can.

Next, a case where the dispersion of this embodiment is applied to a thin film transistor will be described. The thin film transistor is an electronic device in which a gate electrode, a gate insulating film, a semiconductor, a source electrode, and a drain electrode are laminated. The dispersion of the present embodiment can be suitably used as a material for forming a gate electrode, a source electrode, or a drain electrode. The distance (channel length) between the source electrode and the drain electrode is preferably 50 μm or less, more preferably 10 μm or less, and further preferably 2 μm or less. The smaller the channel length, the higher the operating frequency of the thin film transistor.

[Comparative Example 1]
80 g of copper acetate (II) monohydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in a mixed solvent consisting of 800 g of water and 400 g of 1,2-propylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.), and hydrazine (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved. After adding 24 g and stirring, the supernatant and the precipitate were separated by centrifugation. To 2.8 g of the obtained precipitate (1), 0.4 g of PEG-SH800 (trade name, manufactured by Aldrich) and 6.6 g of n-ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) as a solvent were added and dispersed using a homogenizer. By doing so, a dispersion of Comparative Example 1 containing copper (I) oxide particles was obtained.

[Comparative Example 2 and Examples 1 to 10]
Copper (I) oxidation by the same operation as in the above comparative example except that the type and amount of the organic substance added to 2.8 g of the precipitate (1) and the type and amount of the solvent were changed as shown in Table 1, respectively. Dispersions of Comparative Example 2 and Examples 1 to 10 containing individual particles were obtained.

[Measurement and evaluation method]
(1) Formation of coating film Using the dispersion obtained above, an L / S = 5 μm / 5 μm pattern was formed on a PEN film (manufactured by Teijin DuPont Film Co., Ltd.) by reverse printing according to the procedure shown below.

The dispersion was uniformly applied to the PDMS smooth surface, which is the release surface of the blanket, with a bar coater so as to have a dry film thickness of about 400 nm, and air-dried for about 1 minute to obtain a coating film. Then, the removal plate was pressed against the dispersion coating film on the blanket and then separated to remove the coating film in the unnecessary portion. Subsequently, by pressing the PEN film onto the blanket, the pattern formed on the blanket was transferred onto the PEN film to manufacture a substrate for manufacturing a printed wiring board.

(2) Evaluation of fine printability The shape of the pattern obtained in (1) above was observed using an optical microscope and evaluated according to the following criteria.
When L / S = 5 μm / 5 μm pattern could be formed: ◎ (good fine printability)
L / S = 5 μm / 5 μm pattern is generally formed, but the edges of the pattern are uneven: ○
When L / S = 5 μm / 5 μm pattern has poor removal or poor transfer: × (poor fine printability)

(3) Measurement of nitrogen content of non-volatile organic matter Nitrogen content (mass%) of non-volatile organic matter by elemental analysis of the organic component of the coating film on the printed wiring board manufacturing substrate obtained in (1) above. Was measured.

(4) Formation of conductive film Using a far-infrared firing furnace, while introducing a process gas (hydrogen 3% by volume, nitrogen 97% by volume) into the firing furnace at a flow rate of 5 L / min, the above (1) The pattern obtained in 1 was heated to 180 ° C. The heating was carried out for 10 hours.

(5) Volume resistivity of the conductive film The volume resistivity of the conductive film obtained in (3) above was measured using a low resistivity meter Lorester GP manufactured by Mitsubishi Chemical Corporation.

Table 1 shows various evaluation results of the dispersions of Comparative Examples 1 and 2 and Examples 1 to 10.

The names in the table refer to the following compounds.
PEG-SH800: Poly (ethylene glycol) methyl ether thiol with a number average molecular weight of 800 (manufactured by Aldrich)
BYK-145: Disperbyk-145, a phosphate ester salt of a high molecular weight copolymer having a pigment-affinitive group (trade name, manufactured by Big Chemie).
BYK-118: Disperbyk-118, a linear polymer with high polarity and various pigment affinity groups (trade name, manufactured by Big Chemie).
PVP: Polyvinylpyrrolidone (manufactured by Aldrich, product number PVP10-100G)
CEP: Cyanoethyl pullulan (manufactured by Shin-Etsu Chemical Co., Ltd., Cyanoresin CR-S)
NC1: Isopropanol swelling product of nitrocellulose with a solid content of 70% by mass (manufactured by Inabata & Co., Ltd., product number SL-1)
NC2: Isopropanol swelling product of nitrocellulose with a solid content of 70% by mass (manufactured by Inabata & Co., Ltd., product number DLX8-13)
Castor oil: Castor oil (manufactured by Wako Pure Chemical Industries, Ltd., product number 034-01586)
Dibutyl Tartrate: L- (+)-Dibutyl Tartrate (manufactured by Tokyo Chemical Industry Co., Ltd., product number T0005)
Diamil phthalate: Diamil phthalate (manufactured by Tokyo Chemical Industry Co., Ltd., product number P0291)
Dioctyl maleate: Bis maleate (2-ethylhexyl) (manufactured by Tokyo Chemical Industry Co., Ltd., product number M0011)
Ethanol: Ethanol (manufactured by Wako Pure Chemical Industries, Ltd., product number 057-00456)
2-ME: 2-methoxyethanol (manufactured by Wako Pure Chemical Industries, Ltd., product number 058-01106)

In the dispersion according to the present invention, fine wiring can be obtained by coating and firing treatment. Therefore, the dispersion is suitably used for manufacturing printed wiring boards, electronic devices and the like.

Claims (5)

Particles containing copper oxide and
A dispersion for manufacturing a printed wiring board containing a non-volatile organic substance.
The primary particle diameter of the particles is 5 nm or more and less than 100 nm.
The non-volatile organic substance contains a nitrogen-containing organic substance having a nitro group, and the nitrogen content of the non-volatile organic substance is 6% by mass or more and 55% by mass or less. The dispersion according to claim 1 , wherein the nitrogen-containing organic substance has an aldose structure. A substrate for manufacturing a printed wiring board having a substrate and a film formed on the substrate, wherein the film is
Particles containing copper oxide and
Contains non-volatile organic matter,
The primary particle diameter of the particles is 5 nm or more and less than 100 nm.
The non-volatile organic substance contains a nitrogen-containing organic substance having a nitro group, and the nitrogen content of the non-volatile organic substance is 6% by mass or more and 55% by mass or less. A method for manufacturing a substrate for manufacturing a printed wiring board, which comprises applying the dispersion according to claim 1 or 2 onto the substrate and drying it. A method for manufacturing a printed wiring board, which comprises firing the substrate for manufacturing a printed wiring board according to claim 3 to form a sintered film of particles containing copper oxide.