Ink composition, method for producing circuit board, circuit board, primer, and coating agent for primer

Abstract

In order to improve adhesive strength between a substrate and a copper nano-ink sintered layer obtained by sintering an electrically conductive ink containing metal nanoparticles. The present invention contains copper nanoparticles, a copper nanoparticle coating material, a solvent, a dispersing agent, and, as an additive, a compound selected from the group consisting of a hindered phenol-based compound, a thiol-based compound, a sulfide-based compound, a disulfide-based compound, a triaryl phosphine-based compound, a triaryl phosphite-based compound, a diaryl phosphine-based compound, a polyaryl bisphosphine-based compound, an oxamide-based compound and a piperidinol-based compound. The viscosity is 1-100 mPa·s at a measurement temperature of 25°C.

Description

Ink composition, circuit board manufacturing method, circuit board, primer, and coating agent for primer

[0001] The present disclosure relates to an ink composition, a circuit board manufacturing method, a circuit board, a primer, and a coating agent for the primer.

[0002] A known method involves applying conductive ink containing metal nanoparticles only to the required areas by printing such as inkjet printing, and then increasing the metal layer thickness by plating to further reduce the resistance (Patent Document 1). This method allows for a significant simplification of the substrate manufacturing process, and in particular, it significantly reduces the amount of water used, and also reduces CO ２ The inkjet method is a reliable method for producing small quantities of printed wiring boards on demand with minimal time and cost.

[0003] JP 2023-173689 A

[0004] However, there was a problem of reduced adhesion strength between the substrate and the copper nanoink sintered layer, which is made by sintering a conductive ink containing metal nanoparticles.

[0005] Therefore, at least one aspect of the problem to be solved by the present disclosure is to improve the adhesive strength between a copper nanoink sintered layer obtained by sintering a conductive ink containing metal nanoparticles and a substrate. Note that problems that are obvious to a person skilled in the art and can be read from the embodiments and their explanations that are characteristic of the present disclosure and are described in the specification, drawings, etc. of the present disclosure may also be problems to be solved by a divided invention if a divisional application based on the present disclosure is filed.

[0006] In order to achieve the above-mentioned object, the ink composition of the present disclosure comprises copper nanoparticles, a coating material for the copper nanoparticles, a solvent, a dispersant, and an additive compound selected from the group consisting of hindered phenol-based compounds, thiol-based compounds, sulfide-based compounds, disulfide-based compounds, triarylphosphine-based compounds, triarylphosphite-based compounds, diarylphosphine-based compounds, polyarylbisphosphine-based compounds, oxamide-based compounds, and piperidinol-based compounds, and has a viscosity of 1 to 100 mPa·s at a measurement temperature of 25°C.

[0007] Furthermore, in order to achieve the above-mentioned object, the primer of the present disclosure is a circuit board including an insulating substrate, a sintered layer in the form of a wiring pattern containing copper provided on the insulating substrate, and a primer layer formed between the insulating substrate and the sintered layer, and the primer layer is used to form the primer layer, and the primer layer contains, as an additive, a compound selected from the group consisting of hindered phenol-based compounds, thiol-based compounds, sulfide-based compounds, disulfide-based compounds, triarylphosphine-based compounds, triarylphosphite-based compounds, diarylphosphine-based compounds, polyarylbisphosphine-based compounds, oxamide-based compounds, and piperidinol-based compounds.

[0008] Furthermore, in order to achieve the above-mentioned object, the coating agent for primer of the present disclosure is a circuit board having an insulating substrate, a sintered layer in the form of a wiring pattern containing copper provided on the insulating substrate, and a primer layer formed between the insulating substrate and the sintered layer, and the coating agent is coated on the surface of the primer layer as an additive, the additive being a compound selected from the group consisting of hindered phenol-based compounds, thiol-based compounds, sulfide-based compounds, disulfide-based compounds, triarylphosphine-based compounds, triarylphosphite-based compounds, diarylphosphine-based compounds, polyarylbisphosphine-based compounds, oxamide-based compounds, and piperidinol-based compounds.

[0009] According to the present disclosure, it is possible to improve the adhesion strength between a copper nanoink sintered layer formed by sintering a conductive ink containing metal nanoparticles and a substrate.

[0010] 1 is a flowchart showing a process flow of a method for manufacturing a circuit board according to the present disclosure; FIG. 2 is a diagram showing an example of a cross-sectional SEM photograph of a circuit board; FIG. 3 is a schematic diagram showing a mechanism of a decrease in adhesion strength; FIG. 4 is a schematic diagram showing a coating agent applied layer to a primer; FIG. 5 is a table showing examples; FIG. 6 is a table showing examples; FIG. 7 is a table showing examples;

[0011] <Basic Composition of Copper Nanoparticle Ink> The ink composition containing copper nanoparticles according to an embodiment of the present disclosure contains at least copper nanoparticles, a coating material that coats the copper nanoparticles, a solvent, and a dispersant that disperses the copper nanoparticles in the solvent.

[0012] The copper nanoparticles preferably have an average particle size of 1 nm to 200 nm, more preferably 10 nm to 100 nm. If the particle size is too small, the reactivity of the particles may increase, which may reduce the storage stability and stability of the ink. If the particle size is too large, the uniformity of the thin film may decrease, and the ink particles may be more likely to precipitate.

[0013] The coating material is intended to prevent the copper nanoparticles from being easily oxidized, and may be a carboxylic acid, more preferably a monocarboxylic acid having an integer of 6 to 10 carbon atoms, such as hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, or decanoic acid.

[0014] The dispersant is used to disperse the copper nanoparticles covered with a coating material to form an ink, and to uniformly disperse the copper nanoparticles (dispersoid) in the solvent (dispersion medium) and maintain a stable dispersion state without aggregation. The dispersant may be a carboxylic acid-based, thiol-based, phenol-based, phosphoric acid-based, or amine-based compound. Preferably, it may be a carboxylic acid-based compound capable of forming a coordinate bond with copper.

[0015] A more preferred example of a dispersant when octanoic acid is selected as the coating material is, but is not limited to, a polycarboxylic acid. A more preferred polycarboxylic acid is a polycarboxylic acid having a comb structure.

[0016] An example of a polycarboxylic acid with a comb structure is a polymer formed by copolymerizing a monomer such as maleic anhydride or maleic acid with an olefin having a polyoxyalkylene. This structure, in which alkyl chains are attached to the polymer backbone via ether bonds, is sometimes chemically referred to as a "comb," depicting the appearance of each alkyl chain protruding from the backbone as a side chain like the teeth of a comb. The backbone contains a carboxylic acid structure, which covers the copper nanoparticles coated with the coating material, and the alkyl chains connected by ether bonds are thought to interact with the solvent, contributing to the dispersion stability of the solution.

[0017] Other examples of polycarboxylic acids having a comb structure include copolymers of unsaturated dicarboxylic acids (maleic acid, itaconic acid, fumaric acid) and olefins (polytetrahydrofuran, polyethylene glycol, polypropylene glycol) having a polyalkylene glycol structure in the side chain. Thus, the term "comb structure" refers to a structure in which parts of the molecular structure are regularly arranged like the teeth of a comb, and alkyl chains connected by ether bonds are bonded to the main chain of the polycarboxylic acid and extend from the main chain of the polycarboxylic acid like the teeth of a comb.

[0018] The solvent may be an aqueous solvent or an organic solvent, more specifically, glycol ethers such as ethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, or mixtures thereof, and the solvents described below may also be used.

[0019] In addition, stabilizers and other additives may be used.

[0020] The content of copper nanoparticles in the ink composition may be 5 to 60% by weight, or 10 to 30% by weight, by mass. The reason for selecting these ranges is that if the content is too low, there may be a shortage of nanoparticles necessary to form a conductive layer of copper nanoparticles, which may result in the generation of voids such as pinholes, whereas if the content is too high, the particles may be more likely to aggregate in the ink, which may impair the stability of the ink.

[0021] The viscosity of the ink composition is preferably 1 to 100 mPa·s at a measurement temperature of 25°C, as measured using an E-type viscometer or a rheometer. Furthermore, the viscosity is more preferably 1 to 100 mPa·s, and more preferably 1 to 50 mPa·s, at a shear rate of 100 (1 / S) or more. This is because these are conditions suitable for the environment in which the ink is ejected by an inkjet head, and if the viscosity is too high, it will be difficult for the ink to be ejected from the inkjet head.

[0022] An example of a method for adjusting ink viscosity is described below. (1) Selecting a highly hydrophobic solvent or adding a solvent to the above solvent. Examples include, but are not limited to, alkane solvents such as hexane, octane, decane, and cyclohexane, and their alkene and alkyne derivatives. Alkanol solvents such as hexanol, octanol, decanol, and cyclohexanol. Aliphatic ether solvents of ethylene glycol, such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and their diether derivatives. Alternatively, the ethylene glycol unit may be a polymerized form, such as diethylene glycol. Aliphatic ester solvents of ethylene glycol, such as ethylene glycol monomethyl ester, ethylene glycol monoethyl ester, and their diester derivatives. The ethylene glycol unit may also be a polymerized form, such as diethylene glycol. (2) Increasing the amount of solvent. The amount of solvent is preferably 10% by weight or more and 95% by weight or less, more preferably 50% by weight or more and 90% by weight or less, and even more preferably 70% by weight or more and 90% by weight or less. If the amount of solvent is too large, the dispersion stability of the nanoparticles will be poor, and if the amount of solvent is too small, it will be difficult to adjust the viscosity.

[0023] (3) Select a dispersant and a low-molecular-weight dispersant that can adsorb to the nanoparticle surface and reduce the interparticle attractive forces. The molecular weight of the dispersant is preferably 500 g / mol to 100,000 g / mol, more preferably 1,000 g / mol to 50,000 g / mol, and even more preferably 1,000 g / mol to 10,000 g / mol. If the molecular weight is too low, the dispersion stability of the nanoparticles will be poor, while if the molecular weight is too high, the filter passability when mounted on an inkjet head will be poor. Examples of dispersants that can be used include one or more selected from amine compounds, polycarboxylic acids, polyesters, polyvinyl alcohols, polyaldehydes, and salts thereof. Examples include AD3172 manufactured by NOF Corporation, BYK2052 manufactured by BYK, and BYKP105 manufactured by BYK.

[0024] (4) Adding a Silane Coupling Agent - Adding a silane coupling compound having a dimethoxymethylsilyl group, trimethoxysilyl group, diethoxymethylsilyl group, or triethoxysilyl group. Examples include KBM-403, KBM-503, KBM-803, and KBM-1003 manufactured by Shin-Etsu Silicones Co., Ltd. (5) Adding a Surfactant - Known mechanisms by which surfactants increase viscosity include micelle formation, hydrogen bonding, and charge introduction, but some types of surfactants can also decrease the viscosity of the ink composition. Examples include sodium alkyl sulfates such as sodium butyl sulfate, sodium octyl sulfate, and sodium dodecyl sulfate.

[0025] <Circuit Board Manufacturing Method> Next, the basic process flow of the circuit board manufacturing method of the present disclosure will be described with reference to the flowchart shown in FIG.

[0026] First, in step S100, an insulating substrate is prepared. This insulating substrate is an insulating substrate such as a flexible printed circuit board, and may be supplied in the form of a film, sheet, or roll. A primer layer may be formed on the surface of this insulating substrate for various purposes, such as improving the coatability of the ink composition or modifying the surface of the insulating substrate. The primer layer may generally be formed by applying a resin or an adhesion improver that improves the adhesion of ink containing a resin. Alternatively, instead of forming a primer layer, the insulating substrate surface may be subjected to plasma treatment, electron beam treatment, ultraviolet treatment, or the like.

[0027] The insulating substrate may be made of an organic base material such as a thermoplastic resin. Examples of the thermoplastic resin include polyesters such as polyimide, polyamide, polyamideimide, polyethylene terephthalate (PET), and polyethylene naphthalate (PEN), polyamide synthetic resins such as nylons (registered trademarks) identified as nylon 6,10 and nylon 4,6, resins such as polyether ether ketone, acrylonitrile butadiene styrene (ABS), polymethyl methacrylate (PMMA), and polyvinyl chloride, epoxy resins, polystyrene, and polyphenylene sulfide (PPS). Examples of the organic-inorganic base material may include an organic-inorganic composite material such as a glass epoxy resin.

[0028] Other insulating substrates may also be used, such as inorganic substrates, such as ceramics, etc. Other organic substrates may also be used, such as polyvinylidene chloride, polyvinyl alcohol, styrene-acrylonitrile copolymer, polyethylene, styrene-vinyl acetate copolymer, polyacetal, cellulose acetate, polycarbonate, thermoplastic polyurethane, and polytetrafluoroethylene.

[0029] In some cases, the glass transition point range of the insulating substrate material may be selected from 20 ° C. to 250 ° C., 50 ° C. to 200 ° C., or 70 ° C. to 150 ° C. These temperature conditions depend on the material selected, taking into consideration that if the glass transition point is too low, distortion may occur in the insulating substrate when the copper nanoparticles are sintered, and if the glass transition point is too high, the insulating substrate may not soften sufficiently and adhesion to the sintered layer may decrease.

[0030] When the insulating substrate is provided as a film-like material, its thickness may be preferably 5 μm to 3 mm, more preferably 12 μm to 1 mm, and even more preferably 25 μm to 200 μm. The reasons for selecting these thicknesses include the fact that if the thickness is too thin, the strength may be insufficient and distortion may increase during the plating process, and if the thickness is too thick, the cost may increase and the volume and weight of the completed circuit board may increase.

[0031] Next, in step S101, an ink composition containing copper nanoparticles is applied in a wiring pattern using an inkjet printing device (ink application step), thereby forming an ink coating layer on the insulating substrate.

[0032] The diameter of a single ink droplet ejected from an inkjet nozzle of an inkjet printing device is, for example, within a range of 1 μm to 100 μm.

[0033] After the ink coating layer is formed, a drying step may be performed to remove the solvent, etc. The drying step may be a heat treatment or a hot air treatment using a nitrogen or air flow, which leaves the copper nanoparticles on the insulating substrate.

[0034] Next, in step S102, the ink composition is sintered to form a sintered layer (sintering process). Regarding the ink coating layer, in addition to removing components other than the copper nanoparticles, it is necessary to cause bonding, melting, and contact between the copper nanoparticles. The state in which metal nanoparticles are close to each other and bonded while maintaining their shape is called "necking," and the phenomenon in which nanoparticles melt from the necked state and become integrated with a change in shape is also called "fusion." The term "necking" is sometimes used to simply refer to interparticle bonding. In this way, sintering causes the nanoparticles to melt together and bulk, improving conductivity and adhering to the insulating substrate.

[0035] For example, copper nanoparticles can be sintered and bonded together by using photosintering with flash lamp irradiation. The instantaneous heating of a flash discharge lamp is advantageous because heat is applied only to the surface of the substrate, preventing heating inside the substrate.

[0036] The irradiation conditions of the flash lamp can be adjusted appropriately by those skilled in the art, with the input power being a key parameter.

[0037] Next, in step S103, a copper plating layer is formed on the sintered layer (plating step).

[0038] After the ink application process and drying process, a photosintering process is performed, and the formed sintered layer is plated (electrolytic plating or electroless plating). This causes a plating metal (plating layer) to be deposited on the surface and inside of the sintered layer. The plating method is similar to known plating processes using known plating solutions, and specifically may include electroless copper plating, electrolytic copper plating, etc.

[0039] Through the above steps, a circuit board can be manufactured in which copper wiring in a desired pattern is formed on an insulating substrate.

[0040] <Regarding Adhesion Strength with Substrate> Manufactured circuit boards require a considerable degree of adhesion strength between the insulating substrate and the sintered and plated conductive layers. For example, it is preferable for the adhesion strength to be 0.2 N / mm or greater. However, there have been cases where the adhesion strength has decreased during heat resistance reliability testing after manufacture. The present inventors have conducted extensive research into this issue as follows.

[0041] FIG. 2 shows an example of a cross-sectional SEM photograph of an actually manufactured circuit board, and FIG. 3 is a schematic diagram showing the mechanism of the decrease in adhesion strength.

[0042] 2 and 3 show, from bottom to top, the primer layer 2, sintered layer 3, and plating layer 4 formed on the insulating substrate 1. As can be seen from FIG. 2, a primer layer should be present below the sintered layer 3, but a layer that appears bright in the SEM photograph is present. This was presumed to be due to metal, as this layer emits a large amount of secondary electrons, and was thought to be related to the copper present in the sintered layer 3. Based on this, the inventors conducted various studies and came to believe that the adhesion strength decreases due to the following mechanism.

[0043] As shown in Figure 3, copper present in the sintered layer 3 of the copper nanoink undergoes oxidative degradation, generating copper ions that then diffuse into the primer layer 2. A new layer, which may be referred to as a copper ion diffusion layer 21, is then formed between the sintered layer 3 and the primer layer 2. Copper oxide may have formed in the copper ion diffusion layer 21 due to the diffusion of copper ions, which may have resulted in voids due to the difference in volume between the copper and copper oxide. This is thought to reduce the adhesion strength between the sintered layer 3 and the primer layer 2, and ultimately between the conductor layer consisting of the plating layer 4 and the sintered layer 3 and the substrate consisting of the primer layer 2 and the insulating substrate 1. This phenomenon is also thought to occur when the layer adjacent to the sintered layer 3 is the insulating substrate 1 rather than the primer layer 2.

[0044] In addition, there is also a problem that the adhesive strength between the sintered layer and the insulating substrate decreases at the ends of the conductor.

[0045] In order to suppress the occurrence of the phenomenon of a decrease in adhesion strength as described above, the present inventors have conducted extensive research and, as a result of various experiments, have found that an ink composition, a primer, or a coating agent for a primer containing the following specific compound as an additive is preferable.

[0046] (Embodiment as Ink Composition) The ink composition may contain copper nanoparticles, a coating material for the copper nanoparticles, a solvent, a dispersant, and a compound or a derivative thereof described in Groups 1 to 5 described below. In addition, in view of the fact that the ink is ejected from an inkjet printing device, it is preferable that the viscosity at a measurement temperature of 25°C is 1 to 100 mPa·s.

[0047] Furthermore, the content of the additives may be preferably 0.1% by weight or more and less than 5.0% by weight, and more preferably 0.2% by weight or more and 1.0% by weight or less, based on the total weight of the ink composition.

[0048] (Compounds Belonging to Group 1) Compounds belonging to Group 1 are so-called hindered phenol compounds, and include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2-methyl-4,6-bis[(n-octylthio)methyl]phenol, 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis(6-tert-butyl-p-cresol), 4,4'-dihydroxy-3,3',5,5'-tetraisopropylbiphenyl, 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenol, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 6,6'-di-tert-butyl-4,4'-butylidene-di-m-cresol, 4,4',4''-(1-methylpropanyl-3-ylidene)tris(6-tert-butyl-m-cresol), octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, ethylene bis(oxyethylene)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], 3,9-bis{ 2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzylmethyl)-2,4,6-trimethylbenzene, 1,3,5-tris[(4-tert-butyl-3-hydroxy-2,6-dimethylphenyl)methyl]-1,3,5-triazine-2,4,6-trione, N,N'-(hexyl Benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-C7-C9-branched alkyl ester, 2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazin-2-ylamino)phenol, bis[3,3-bis(4'-hydroxy-3'-tert-butylphenyl)-butanoic acid] glycol ester, bis(1,2, The compound may be at least one compound selected from the first group consisting of 2,6,6-pentamethyl-4-piperidyl)butyl(3,5-di-tert-butyl-4-hydroxybenzyl)malonate, 2-hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide, N'1,N'12-bis(2-hydroxybenzoyl)dodecane dihydrazide, and N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, or a derivative thereof.

[0049] These first-class compounds are hindered phenolic compounds, which contain bulky substituents (often tert-butyl groups) at the ortho or para positions of the phenolic skeleton. Some compounds contain multiple phenolic skeletons. Furthermore, some compounds contain nitrogen-containing moieties, such as hydrazides or triazines, in addition to the phenolic skeleton. It is clear that compounds within the scope of these compounds can also be used.

[0050] (Compounds Belonging to Group 2) Compounds belonging to Group 2 are thiol compounds, sulfide compounds, and disulfide compounds containing a sulfur atom, and include pentaerythritol tetrakis(2-mercaptoacetate), dioctadecyl sulfide, tris[2-tert-butyl-5-methyl-4-thio-5'-tert-butyl'-4'-hydroxy-2-methylphenyl]phenyl phosphite, 2,2-bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diylbis[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diylbis[3-(dodecylthio)-1-oxopropoxy]methyl] ...

[0039] The compound may be at least one compound selected from a second group consisting of 3-{3-[(3-sulfanylpropanoyl)oxy]-2,2-bis({[(3-sulfanylpropanoyl)oxy]methyl})propoxy}-2,2-bis({[(3-sulfanylpropanoyl)oxy]methyl})propyl 3-sulfanylpropanoate, or a derivative thereof.

[0051] The compounds belonging to this second group are thiol compounds, sulfide compounds, and disulfide compounds, which are all organic compounds containing sulfur atoms, and some of them have a thioether bond or a thiol group, a highly hydrophobic partial structure such as a long-chain alkyl group or a phenyl group, and also have other functional groups such as an ester bond or a phosphite bond. It is also clear that compounds within a range that can be recognized from the commonalities of these compounds can also be employed.

[0052] (Compounds Belonging to Group 3) The compounds belonging to Group 3 are phosphorus-based compounds, triarylphosphine-based compounds, triarylphosphite-based compounds, diarylphosphine-based compounds, or polyarylbisphosphine-based compounds, and may be at least one compound selected from Group 3 consisting of triphenyl phosphite, tri-o-tolyl phosphite, tri-p-tolyl phosphine, methyldiphenylphosphine, ethyldiphenylphosphine, triphenylphosphine, tri(p-tolyl)phosphine, tris(4-fluorophenyl)phosphine, bis(diphenylphosphino)methane, diphenyl-1-pyrenylphosphine, and tetrakis(2,4-di-tert-butylphenyl)4,4'-biphenylene-di-phosphonite, or derivatives thereof.

[0053] Compounds belonging to this third group include phosphine compounds having three aryl groups and phosphite compounds having three aryl groups, which have a phosphorous acid skeleton. Other compounds are also phosphine compounds or bisphosphine compounds having at least two aryl groups. It is clear that compounds within a range that can be recognized from the commonality of these compounds can also be employed.

[0054] (Compounds Belonging to Group 4) The compounds belonging to Group 4 are oxamide-based compounds, and may be at least one compound selected from Group 4 consisting of 2-hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide and N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, or a derivative thereof.

[0055] Compounds belonging to this fourth group have an oxamide skeleton or a structure similar thereto as part of their structure, an aryl group containing a benzene ring, a hydroxyl group, and a hydrazide or hydrazine bond. Therefore, these compounds may be called aromatic hydroxyhydrazide / hydrazine compounds. It is clear that compounds within the scope of these compounds that can be recognized based on their commonalities can also be used.

[0056] (Compounds Belonging to Group 5) The compounds belonging to Group 5 are piperidinol-based compounds, and may be at least one compound selected from Group 5 consisting of propanedioic acid, [(4-methoxyphenyl)-methylene]-bis(1,2,2,6,6-pentamethyl-4-piperidinyl) ester, 2,2,4,4-tetramethyl-21-oxo-7oxa-3,20-diazadispiro[5.1.11.2]-heneicosane-20-propanoic acid dodecyl ester / tetradecyl ester, esters of 2,2,6,6-tetramethyl-4-piperidinol and higher fatty acids, 2,2,6,6-tetramethylpiperidine, 2,2,6,6-tetramethylpiperidine 1-oxyl free radical, and 4-amino-2,2,6,6-tetramethylpiperidine, or derivatives thereof.

[0057] These compounds belonging to Group 5 have a piperidine skeleton as part of their structure, and some have a hydroxyl group bonded to the piperidine skeleton. Furthermore, all of them have a 2,2,6,6-tetramethylpiperidine skeleton and can also be called hindered amine compounds. Furthermore, it is clear that compounds within a range that can be recognized based on the commonality of these compounds can also be employed.

[0058] (Example of a method for producing an ink composition) <Procedure for producing copper nanoparticles> The procedure for producing copper nanoparticles is explained below in chronological order. 1. A water bath, a three-one motor, a reflux tower, a 3000 mL four-neck separable flask, a thermocouple, a dropping tube, and an automatic dropping device are assembled in a draft chamber. 2. Copper oxide (the raw materials for copper nanoparticles), a solvent alcohol such as 2-propanol (IPA) or ethanol, and a coating material such as octanoic acid are weighed and placed in the separable flask. 3. The reaction solution is stirred at a predetermined stirring speed (e.g., 180 rpm) in an air atmosphere. 4. The reaction solution is heated to a predetermined temperature (70°C in this case), and hydrazine is added dropwise to the reaction solution using the automatic dropping device. 5. After the hydrazine addition is complete, heating and stirring is continued for a predetermined time (2 hours in this case). 6. The mixture is cooled with stirring until the temperature drops to or below the predetermined temperature (40°C in this case). 7. Once the temperature has dropped below a specified level, decantation is performed using a solvent such as methanol, ethanol, or acetone to purify the copper nanoparticles. 8. The resulting dark brown precipitate is transferred to a Separable Nascent flask, and a high-boiling point solvent (solvent) such as diethylene glycol monobutyl ether is added. 9. The low-boiling point solvent is removed by vacuum distillation using an evaporator. 10. The mixture is dried under a nitrogen stream to obtain copper nanoparticle powder. In this way, copper nanoparticles, which are the precursors to ink, can be obtained. Below, we will explain how to manufacture ink using these copper nanoparticles.

[0059] Next, an example of a method for producing an ink composition containing the additives described above will be described. <Ink Production Procedure> 11. Weigh out the copper nanoparticle powder into a container compatible with planetary mixing. 12. Weigh out a dispersant such as a comb-shaped polycarboxylic acid and place it in the container. 13. Use planetary mixing to check the mixing condition. 14. Weigh out the solvent and add the specified amount of solvent weighed out to the container. 15. Use planetary mixing to check the mixing condition. 16. Place the remaining solvent in the container. 17. Place the additives in the container. 18. Use planetary mixing to make a final check of the mixing condition.

[0060] The present inventors have also found that the compounds belonging to the above Groups 1 to 5, which are used as additives to ink compositions, are also useful as primers and coating agents for primers, because they share the same functions of not being thermally decomposed by the heat during sintering and preventing a decrease in adhesion strength.

[0061] (Embodiment as a Primer) The primer is a mixture of the compounds described in the first to fifth groups or derivatives thereof for forming a primer layer of a circuit board including an insulating substrate, a sintered layer in the form of a wiring pattern containing copper provided on the insulating substrate, and a primer layer formed between the insulating substrate and the sintered layer.

[0062] An existing primer can be used as the base primer. The primer may be, for example, polyimide, polyamide, polyamideimide, polyethylene terephthalate, polyethylene naphthalate, polyether ether ketone, acrylonitrile butadiene styrene, polymethyl methacrylate, polystyrene, polyphenylene sulfide, polyvinyl chloride, epoxy resin, or glass epoxy resin. The primer material and the insulating substrate material may be the same material, taking into account factors such as thermal expansion coefficient, mechanical properties, and chemical stability, or may be a compound based on the same material but with additives added. In a primer in which an additive is mixed with the base primer, the additive may preferably be present in an amount of 0.1 weight percent or more but less than 5.0 weight percent, and more preferably 0.2 weight percent or more but 1.0 weight percent.

[0063] The primer may also contain the following compounds as additives, even though they are not suitable for addition to ink compositions. Specifically, these include pentaerythritol tetrakis[3-laurylthiopropionate] (which can be classified as the second group above), tris(2,4-di-tert-butylphenyl)phosphite (which can be classified as the third group above), and N'1,N'12-bis(2-hydroxybenzoyl)dodecane dihydrazide (which can be classified as the fourth group above). These compounds have low solubility in solvents, more specifically glycol ether solvents, making them difficult to formulate into inks. This is because low solubility prevents them from passing through the filter of the inkjet head and prevents them from being ejected. However, they can be used as primers when applied directly to insulating substrates.

[0064] In addition, a mixed ester of 1,2,3,4-butanetetracarboxylic acid with 2,2,6,6-tetramethyl-4-piperidinol and 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane, or a derivative thereof, can be used. These compounds can be categorized into the fifth group.

[0065] (Embodiment as a primer coating agent) The primer coating agent includes a compound that can be used in the primer, which is coated on the surface of the primer layer of a circuit board including an insulating substrate, a sintered layer in the form of a copper-containing wiring pattern provided on the insulating substrate, and a primer layer formed between the insulating substrate and the sintered layer. This has been explained in the above-mentioned first to fifth groups and the compounds that can be used in the primer, so further explanation will be omitted.

[0066] An example of a method for producing a primer coating agent is shown below. The additive compound belonging to Group 2 (an example of an additive compound: pentaerythritol tetrakis[3-laurylthiopropionate]) is diluted and blended in a solvent (an example of a solvent: ethylene glycol monomethyl ether) and applied to an insulating substrate (an example of an insulating substrate: polyimide) coated with a predetermined primer using a 10 μm bar coat printing method. The coated substrate is then heated and dried at 185°C for 1 hour. The above is merely an example, and the additive compound, solvent, insulating substrate, printing method, and drying conditions are not limited to these.

[0067] 4 is a schematic diagram showing an application image when a primer coating agent is used. After forming the primer layer 2, the primer coating agent is applied and dried to form a primer coating agent application layer 22.

[0068] The primer coating agent can be, for example, an existing primer to which the additive has been added. In the primer coating agent in which the additive has been mixed with the primer to which the additive has been added, the additive content is preferably 0.1% by weight or more and less than 5.0%, more preferably 0.2% by weight or more and 1.0% by weight or less.

[0069] <Examples> (Heat resistance reliability test and peel test of circuit boards prepared using ink composition) Circuit boards were prepared using the ink compositions according to the above embodiments. The prepared circuit boards were subjected to the following peel test before and after a 240-hour heat resistance reliability test in an environment of 150°C, and changes in adhesion strength were evaluated. In all of the following examples, the circuit boards were prepared not by inkjet pattern formation, but by forming a copper sintered layer and a copper plated layer on the entire surface of an insulating substrate or in an area large enough to allow for a peel test, to prepare circuit board samples.

[0070] <Ink Composition Production Example> 15 parts of copper nanoparticles, 1 part of a polycarboxylic acid-based dispersant, 10 parts of 2-ethoxyethanol (manufactured by Tokyo Chemical Industry Co., Ltd.), 15 parts of 2-(2-n-butoxyethoxy)ethanol (manufactured by Tokyo Chemical Industry Co., Ltd.) (diethylene glycol monobutyl ether), 10 parts of 3-methoxy-methylbutanol (manufactured by Tokyo Chemical Industry Co., Ltd.), and 47 parts of 2-(2-methoxyethoxy)ethanol (manufactured by Tokyo Chemical Industry Co., Ltd.) (diethylene glycol monomethyl ether) were blended in a container and dispersed using a planetary rotary mixer. 0.2 to 1.0 parts of various additives were blended thereto, and the mixture was dispersed using the planetary rotary mixer as well. A copper-brown additive-containing copper ink composition was obtained. A circuit board was fabricated using the resulting ink composition.

[0071] <Peel Test> A peel test to check the adhesive strength of the plating layer to the substrate is performed at a 90-degree angle in accordance with the U.S. UL standard, more specifically, UL 796 F. In the peel test, multiple peeling tests are performed on multiple test piece widths.

[0072] (Ink Examples and Comparative Examples) Figure 5 is a table showing the adhesion strength of ink compositions according to the above ink production examples, Examples 1-1 to 1-7 and Comparative Examples 1-1 to 1-6, showing the change in the average value of the initial adhesion strength (N / mm) after production and the adhesion strength (N / mm) after 240 hours of a heat resistance reliability test at 150°C. The viscosity of the ink composition was measured using an E-type viscometer (manufactured by Eiko Seiki Co., Ltd.) at a cone plate rotation speed of 20 rpm (corresponding to a shear rate of 150 (1 / S)), a measurement temperature of 25°C, and a measurement time of 40 seconds. The same applies hereinafter. The additives used in Examples 1-1 to 1-7 and Comparative Examples 1-1 to 1-6 are as follows: Example 1-1: 0.2 wt% of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] as an additive Example 1-2: 1.0 wt% of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] as an additive Example 1-3: 0.2 wt% of 2-methyl-4,6-bis[(n-octylthio)methyl]phenol as an additive Example 1-4: 0.2 wt% of 2,6-di-tert-butyl-p-cresol as an additive Example 1-5: 0.2 wt% of 2,2'-methylenebis(6-tert-butyl-p-cresol) as an additive Example 1-6: 0.2 wt% of 4,4'-dihydroxy-3,3',5,5'-tetraisopropylbiphenyl as an additive Example 1-7: 0.2 wt% of 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenol as an additive Comparative Example 1-1: No additive was added (reference) Comparative Example 1-2: 5.0 wt% of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] as an additive Comparative Example 1-3: 0.2 wt% of trimethylolpropane triacrylate as an additive Comparative Example 1-4: 0.2 wt% of tris(2,4-di-tert-butylphenyl)phosphite as an additive Comparative Example 1-5: 0.2 wt% of pentaerythritol tetrakis[3-laurylthiopropionate] as an additive Comparative Example 1-6: 0.2 wt% of N'1,N'12-bis(2-hydroxybenzoyl)dodecane dihydrazide as an additive

[0073] According to this, after 240 hours of the heat resistance reliability test, all of Examples 1-1 to 1-7 had an adhesion strength of 0.75 N / mm or more before the test began, and maintained an adhesion strength of 0.4 N / mm or more even after 240 hours of the heat resistance reliability test. This demonstrates that adding these additives to the ink composition also has the effect of suppressing a decrease in adhesion strength. Furthermore, all Examples had a viscosity of 1 to 10 mPa s at a measurement temperature of 25°C, making them easy to prepare into inks and particularly suitable for inkjet applications.

[0074] In Comparative Example 1-1, no additives were added, and the adhesion strength clearly decreased after the heat resistance reliability test. Furthermore, in Comparative Example 1-2, the adhesion strength was so low that it was impossible to measure. In Comparative Example 1-3, an additive different from the compounds belonging to Groups 1 to 5 of the present disclosure was used, and a significant decrease in adhesion strength was observed. Furthermore, in Comparative Examples 1-4 to 1-6, the solubility in the solvent contained in the ink composition was low, making it difficult to produce ink in the first place. However, as described below, they are effective as primers and coating agents for primers, which are applications other than inks.

[0075] (Example of Primer) A similar test was also carried out on the primer. Fig. 6 is a table showing the adhesion strength of Examples 2-1 to 2-4, showing the change in the average value of the initial adhesion strength (N / mm) after production and the adhesion strength (N / mm) after 240 hours of a heat resistance reliability test at 150°C. The additives in Examples 2-1 to 2-4 are as follows. Example 2-1: 1% by weight of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] as an additive Example 2-2: 0.2% by weight of tris(2,4-di-tert-butylphenyl)phosphite as an additive Example 2-3: 1% by weight of a mixed ester of 1,2,3,4-butanetetracarboxylic acid with 2,2,6,6-tetramethyl-4-piperidinol and 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane as an additive Example 2-4: 1% by weight of pentaerythritol tetrakis[3-laurylthiopropionate] as an additive

[0076] According to this, after 240 hours of the heat resistance reliability test, all of Examples 2-1 to 2-4 had an adhesion strength of 1.0 N / mm or more before the test began, and maintained an adhesion strength of 0.3 N / mm or more even after 240 hours of the heat resistance reliability test. The initial adhesion strength of Examples 2-2 to 2-4 was so high that it was impossible to measure because the conductor broke during peeling. Conversely, the adhesion strength was found to be 2.0 N / mm or more (so high that it was impossible to measure). Therefore, it was found that adding this additive to the primer also has the effect of suppressing a decrease in adhesion strength.

[0077] (Example of primer coating agent) A similar test was also conducted on the primer coating agent. Figure 7 is a table showing the adhesion strength of Examples 3-1 to 3-5, showing the change in the average value of the initial adhesion strength (N / mm) after production and the adhesion strength (N / mm) after 240 hours of a heat resistance reliability test at 150°C. The additives are as follows: Example 3-1: Pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] Example 3-2: Tris(2,4-di-tert-butylphenyl)phosphite Example 3-3: Mixed ester of 1,2,3,4-butanetetracarboxylic acid with 2,2,6,6-tetramethyl-4-piperidinol and 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane Example 3-4: Pentaerythritol tetrakis[3-laurylthiopropionate] Example 3-5: N'1,N'12-bis(2-hydroxybenzoyl)dodecane dihydrazide

[0078] In addition, the initial adhesion strength of Examples 3-2 to 3-4 was too high to be measured because the conductor broke during peeling. Conversely, it was found that the adhesion strength was 2.0 N / mm or more (so high that it was impossible to measure).

[0079] According to this, after 240 hours of the heat resistance reliability test, all of Examples 3-1 to 3-5 had an adhesion strength of 1.0 N / mm or more before the test started, and maintained an adhesion strength of 0.3 N / mm or more even after 240 hours of the heat resistance reliability test. Therefore, it was found that the coating agent for primer also has the effect of suppressing a decrease in adhesion strength.

[0080] The new technology of this disclosure can be realized in various other forms, and part of the content can be omitted, modified, or replaced within the scope of the gist of this disclosure. The embodiments and modifications shown in this disclosure are also within the scope and gist of this disclosure, and are treated as technologies that should be protected by the claims, and are equivalent or similar to them.

[0081] The following additional notes apply to embodiments included in the present disclosure. [1] An ink composition comprising copper nanoparticles, a coating material for the copper nanoparticles, a solvent, a dispersant, and an additive selected from the group consisting of a hindered phenol compound, a thiol compound, a sulfide compound, a disulfide compound, a triarylphosphine compound, a triarylphosphite compound, a diarylphosphine compound, a polyarylbisphosphine compound, an oxamide compound, and a piperidinol compound, and having a viscosity of 1 to 100 mPa·s at a measurement temperature of 25°C. [2] The hindered phenol compounds include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2-methyl-4,6-bis[(n-octylthio)methyl]phenol, 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis(6-tert-butyl-p-cresol), 4,4'-dihydroxy-3,3',5,5'- Tetraisopropylbiphenyl, 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenol, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 6,6'-di-tert-butyl-4,4'-butylidenedi-m-cresol, 4,4',4''-(1-methylpropanyl octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, ethylene bis(oxyethylene)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy] -1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzylmethyl)-2,4,6-trimethylbenzene, 1,3,5-tris[(4-tert-butyl-3-hydroxy-2,6-dimethylphenyl)methyl]-1,3,5-triazine-2,4,6-trione, N,N'-(hexane-1,6-diyl)bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide], benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-C7-C9-branched alkyl ester, 2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazin-2-ylamino)phenol, bis[3,3-bis(4'-hydroxy-3'-tert-butylphenyl)-butanoic acid] glycol ester, bis(1,2,2,6,6-pentaerythritol)

[0023] The ink composition according to [1], wherein the at least one compound selected from a first group consisting of N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, N-(3 ... [3] The thiol compound, sulfide compound, or disulfide compound is selected from the group consisting of pentaerythritol tetrakis(2-mercaptoacetate), dioctadecyl sulfide, tris[2-tert-butyl-5-methyl-4-thio-5'-tert-butyl'-4'-hydroxy-2-methylphenyl]phenyl phosphite, 2,2-bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diylbis[3-(dodecylthio)propionate], di(tridecyl)3,3'-thiodipropionate, 2-mercaptobenzimidazole, and 3-{3-[(3-sulfanylpropanoyl)oxy]-2,2-bis({[(3-sulfanylpropanoyl)oxy]methyl})propoxy}-2,The ink composition according to [1], wherein the triarylphosphine compound, triarylphosphite compound, diarylphosphine compound, or polyarylbisphosphine compound is at least one compound selected from a second group consisting of triphenylphosphite, tri-o-tolylphosphite, tri-p-tolylphosphine, methyldiphenylphosphine, ethyldiphenylphosphine, triphenylphosphine, tri(p-tolyl)phosphine, tris(4-fluorophenyl)phosphine, bis(diphenylphosphino)methane, diphenyl-1-pyrenylphosphine, and tetrakis(2,4-di-tert-butylphenyl)4,4'-biphenylene-di-phosphonite, or a derivative thereof. [5] The ink composition according to [1], wherein the oxamide compound is at least one compound selected from a fourth group consisting of 2-hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide and N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, or a derivative thereof. [6] The piperidinol compound is propanedioic acid, [(4-methoxyphenyl)-methylene]-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)ester, 2,2,4,4-tetramethyl-21-oxo-7oxa-3. 20-Diazadispiro[5.1.11.2]-heneicosane-20-propanoic acid dodecyl ester / tetradecyl ester, esters of 2,2,6,6-tetramethyl-4-piperidinol with higher fatty acids, 2,2,6,6-tetramethylpiperidine, 2,2,6,6-tetramethylpiperidine 1-oxyl free radical, and 4-amino-2,2,6,

[0013] The ink composition according to [1], wherein the ink composition is at least one compound selected from a fifth group consisting of 6-tetramethylpiperidine or a derivative thereof. [7] A method for producing a circuit board, comprising: an ink application step of applying the ink composition according to any one of [2] to [6] in the form of a wiring pattern onto an insulating substrate using an inkjet printing device; a sintering step of sintering the ink composition to form a sintered layer; and a plating step of forming a copper plating layer on the sintered layer. [8] A circuit board, comprising: an insulating substrate; a sintered layer in the form of a wiring pattern formed on the insulating substrate using the ink composition according to any one of [2] to [6]; and a copper plating layer formed on the sintered layer, wherein the adhesion strength between the sintered layer and the plating layer and the insulating substrate is 0.2 N / mm or more. [9] A circuit board including an insulating substrate, a sintered layer in the form of a wiring pattern containing copper provided on the insulating substrate, and a primer layer formed between the insulating substrate and the sintered layer, the primer being used in forming the primer layer and including, as an additive, a compound selected from the group consisting of hindered phenol compounds, thiol compounds, sulfide compounds, disulfide compounds, triarylphosphine compounds, triarylphosphite compounds, diarylphosphine compounds, polyarylbisphosphine compounds, oxamide compounds, and piperidinol compounds.

[10] A circuit board including an insulating substrate, a sintered layer in the form of a wiring pattern containing copper provided on the insulating substrate, and a primer layer formed between the insulating substrate and the sintered layer, the primer coating agent comprising an additive selected from the group consisting of hindered phenol compounds, thiol compounds, sulfide compounds, disulfide compounds, triarylphosphine compounds, triarylphosphite compounds, diarylphosphine compounds, polyarylbisphosphine compounds, oxamide compounds, and piperidinol compounds.

[11] The additive is pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2-methyl-4,6-bis[(n-octylthio)methyl]phenol, 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis(6-tert-butyl-p-cresol), 4,4'-dihydroxy-3,3',5,5'-tetraisopropylbiphenyl, 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenol, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 6,6'-di-tert-butyl-4,4'-butylidenedi-m-cresol, 4,4',4'' -(1-methylpropanyl-3-ylidene)tris(6-tert-butyl-m-cresol), octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, ethylene bis(oxyethylene)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane, 1,3,5-tris( 3,5-di-tert-butyl-4-hydroxybenzylmethyl)-2,4,6-trimethylbenzene, 1,3,5-tris[(4-tert-butyl-3-hydroxy-2,6-dimethylphenyl)methyl]-1,3,5-triazine-2,4,6-trione, N,N'-(hexane-1,6-diyl)bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide], benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-C7-C9-branched alkyl ester, 2,6-di-tert-butyl N,N'-bis(2-hydroxybenzoyl)-1,3,5-triazin-2-ylamino)phenol, bis[3,3-bis(4'-hydroxy-3'-tert-butylphenyl)-butanoic acid] glycol ester, bis(1,2,2,6,6-pentamethyl-4-piperidyl)butyl(3,5-di-tert-butyl-4-hydroxybenzyl)malonate, 2-hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide, N'1,N'12-bis(2-hydroxybenzoyl)dodecane dihydrazide, and N,N'-bis[3-(3,The first group consisting of [2-tert-butyl-5-methyl-4-thio-5'-tert-butyl'-4'-hydroxy-2-methylphenyl]phenyl phosphite, 2,2-bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3 a second group consisting of 3-(tridecyl)-2,2-bis[3-(dodecylthio)propionate], di(tridecyl)3,3'-thiodipropionate, 2-mercaptobenzimidazole, and 3-{3-[(3-sulfanylpropanoyl)oxy]-2,2-bis({[(3-sulfanylpropanoyl)oxy]methyl})propoxy}-2,2-bis({[(3-sulfanylpropanoyl)oxy]methyl})propyl 3-sulfanylpropanoate; triphenyl phosphite, tri-o-tolyl phosphite, tri-p-tolyl phosphite, methyldiphenylphosphine, ethyldiphenylphosphine, triphenylphosphine, tri(p-tolyl)phosphine, tris(4-fluorophenyl)phosphine, bis(diphenylphosphino)methane, diphenyl-1-pyrenylphosphine, and tetrakis(2,4-di-tert-butylphenyl)4,4'-biphenylene-di-phospho the third group consisting of 2-hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide, and the fourth group consisting of N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, propanedioic acid, [(4-methoxyphenyl)-methylene]-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)ester, 2,2,4,4-tetramethyl-21-oxo-7oxa-3. 20-Diazadispiro[5.1.11.2]-heneicosane-20-propanoic acid dodecyl ester / tetradecyl ester, esters of 2,2,6,6-tetramethyl-4-piperidinol with higher fatty acids, 2,2,6,6-tetramethylpiperidine, 2,2,6,6-tetramethylpiperidine 1-oxyl free radical, and 4-amino-2,2,6,The primer according to [9], wherein the additive is at least one compound selected from a fifth group consisting of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2-methyl-4,6-bis[(n-octylthio)methyl]phenol, 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis(6-tert-butyl-p-cresol), 4,4'-dihydroxy-3,3',5,5'-tetraisopropylbiphenyl, 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methyl phenol, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 6,6'-di-tert-butyl-4,4'-butylidene-m-cresol, 4,4',4''-(1-methylpropanyl-3-ylidene)tris(6-tert-butyl-m-cresol), octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, ethylenebis(oxyethylene) Benzene)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzylmethyl)-2,4,6-trimethylbenzene, 1,3,5-tris[(4-tert-butyl-3-hydrox- 2,6-Di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazin-2-ylamino)phenol, bis[3,a first group consisting of 3-bis(4'-hydroxy-3'-tert-butylphenyl)-butanoic acid] glycol ester, bis(1,2,2,6,6-pentamethyl-4-piperidyl)butyl(3,5-di-tert-butyl-4-hydroxybenzyl)malonate, 2-hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide, N'1,N'12-bis(2-hydroxybenzoyl)dodecane dihydrazide, and N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine; Pentaerythritol tetrakis(2-mercaptoacetate), dioctadecyl sulfide, tris[2-tert-butyl-5-methyl-4-thio-5'-tert-butyl'-4'-hydroxy-2-methylphenyl]phenyl phosphite, 2,2-bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diylbis[3-(dodecylthio)propionate], di(tridecyl)3,3'-thiodipropionate, 2-mercaptobenzimidazole, and 3-{3-[(3-sulfanylpropano a second group consisting of]-2,2-bis({[(3-sulfanylpropanoyl)oxy]methyl})propoxy}-2,2-bis({[(3-sulfanylpropanoyl)oxy]methyl})propyl 3-sulfanylpropanoate, triphenyl phosphite, tri-o-tolyl phosphite, tri-p-tolyl phosphite, methyldiphenylphosphine, ethyldiphenylphosphine, triphenylphosphine, tri(p-tolyl)phosphine, tris(4-fluorophenyl)phosphine, bis(diphenylphosphino) a third group consisting of methane, diphenyl-1-pyrenylphosphine, and tetrakis(2,4-di-tert-butylphenyl)4,4'-biphenylene-di-phosphonite; a fourth group consisting of 2-hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide and N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine; a fourth group consisting of propanedioic acid, [(4-methoxyphenyl)-methylene]-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)ester, 2,2,4,The primer coating agent according to

[10] , which is at least one compound selected from Group 5 consisting of 4-tetramethyl-21-oxo-7-oxa-3,20-diazadispiro[5.1.11.2]-heneicosane-20-propanoic acid dodecyl ester / tetradecyl ester, esters of 2,2,6,6-tetramethyl-4-piperidinol and higher fatty acids, 2,2,6,6-tetramethylpiperidine, 2,2,6,6-tetramethylpiperidine 1-oxyl free radical, and 4-amino-2,2,6,6-tetramethylpiperidine, or a derivative thereof.

[0082] REFERENCE SIGNS LIST 1 insulating substrate 2 primer layer 21 copper ion diffusion layer 3 sintered layer 4 plating layer

Claims

1. An ink composition comprising copper nanoparticles, a coating material for the copper nanoparticles, a solvent, a dispersant, and an additive selected from the group consisting of hindered phenol compounds, thiol compounds, sulfide compounds, disulfide compounds, triarylphosphine compounds, triarylphosphite compounds, diarylphosphine compounds, polyarylbisphosphine compounds, oxamide compounds, and piperidinol compounds, and having a viscosity of 1 to 100 mPa·s at a measurement temperature of 25°C.

2. The hindered phenol compound is pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2-methyl-4,6-bis[(n-octylthio)methyl]phenol, 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis(6-tert-butyl-p-cresol), 4,4'-dihydroxy-3,3',5,5'-tetraisopropylbiphenyl, 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenol, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 6,6'-di-tert-butyl-4,4'-butylidene-di-m-cresol, 4,4',4''-(1-methylpropanyl-3-ylidene)tris(6-tert-butyl-m-cresol), octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, ethylene bis(oxyethylene)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], 3,9-bis{2-[ 3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzylmethyl)-2,4,6-trimethylbenzene, 1,3,5-tris[(4-tert-butyl-3-hydroxy-2,6-dimethylphenyl)methyl]-1,3,5-triazine-2,4,6-trione, N,N'-(hexane-1,6 -diyl)bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide], benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-C7-C9-branched alkyl ester, 2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazin-2-ylamino)phenol, bis[3,3-bis(4'-hydroxy-3'-tert-butylphenyl)-butanoic acid] glycol ester, bis(1,2,2,6,6-penta The ink composition according to claim 1, wherein the compound is at least one compound selected from a first group consisting of (methyl-4-piperidyl)butyl(3,5-di-tert-butyl-4-hydroxybenzyl)malonate, 2-hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide, N'1,N'12-bis(2-hydroxybenzoyl)dodecane dihydrazide, and N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, or a derivative thereof.

3. The thiol compound, sulfide compound, or disulfide compound is pentaerythritol tetrakis(2-mercaptoacetate), dioctadecyl sulfide, tris[2-tert-butyl-5-methyl-4-thio-5'-tert-butyl'-4'-hydroxy-2-methylphenyl]phenyl phosphite, 2,2-bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diylbis[3-(dodecylthio)propionate] 2. The ink composition according to claim 1, wherein the at least one compound selected from a second group consisting of 3-(2 ...

4. The ink composition according to claim 1, wherein the triarylphosphine compound, triarylphosphite compound, diarylphosphine compound, or polyarylbisphosphine compound is at least one compound selected from a third group consisting of triphenyl phosphite, tri-o-tolyl phosphite, tri-p-tolyl phosphine, methyldiphenylphosphine, ethyldiphenylphosphine, triphenylphosphine, tri(p-tolyl)phosphine, tris(4-fluorophenyl)phosphine, bis(diphenylphosphino)methane, diphenyl-1-pyrenylphosphine, and tetrakis(2,4-di-tert-butylphenyl)4,4'-biphenylene-di-phosphonite, or a derivative thereof.

5. The ink composition according to claim 1, wherein the oxamide compound is at least one compound selected from a fourth group consisting of 2-hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide and N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, or a derivative thereof.

6. The ink composition according to claim 1, wherein the piperidinol compound is at least one compound selected from Group 5 consisting of propanedioic acid, [(4-methoxyphenyl)-methylene]-bis(1,2,2,6,6-pentamethyl-4-piperidinyl) ester, 2,2,4,4-tetramethyl-21-oxo-7oxa-3,20-diazadispiro[5.1.11.2]-heneicosane-20-propanoic acid dodecyl ester / tetradecyl ester, esters of 2,2,6,6-tetramethyl-4-piperidinol and higher fatty acids, 2,2,6,6-tetramethylpiperidine, 2,2,6,6-tetramethylpiperidine-1-oxyl free radical, and 4-amino-2,2,6,6-tetramethylpiperidine, or a derivative thereof.

7. A method for manufacturing a circuit board, comprising: an ink application step of applying the ink composition according to any one of claims 2 to 6 in the form of a wiring pattern onto an insulating substrate using an inkjet printing device; a sintering step of sintering the ink composition to form a sintered layer; and a plating step of forming a copper plating layer on the sintered layer.

8. A circuit board comprising an insulating substrate, a sintered layer in the form of a wiring pattern formed on the insulating substrate using the ink composition according to any one of claims 2 to 6, and a copper plating layer formed on the sintered layer, wherein the adhesive strength between the sintered layer and the plating layer and the insulating substrate is 0.2 N / mm or more.

9. A circuit board including an insulating substrate, a sintered layer in the form of a wiring pattern containing copper provided on the insulating substrate, and a primer layer formed between the insulating substrate and the sintered layer, the primer being used in forming the primer layer and containing, as an additive, a compound selected from the group consisting of hindered phenol compounds, thiol compounds, sulfide compounds, disulfide compounds, triarylphosphine compounds, triarylphosphite compounds, diarylphosphine compounds, polyarylbisphosphine compounds, oxamide compounds, and piperidinol compounds.

10. A circuit board having an insulating substrate, a sintered layer in the form of a wiring pattern containing copper provided on the insulating substrate, and a primer layer formed between the insulating substrate and the sintered layer, the primer coating agent being coated on the surface of the primer layer and comprising, as an additive, a compound selected from the group consisting of hindered phenol compounds, thiol compounds, sulfide compounds, disulfide compounds, triarylphosphine compounds, triarylphosphite compounds, diarylphosphine compounds, polyarylbisphosphine compounds, oxamide compounds, and piperidinol compounds.

11. The additive is pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2-methyl-4,6-bis[(n-octylthio)methyl]phenol, 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis(6-tert-butyl-p-cresol), 4,4'-dihydroxy-3,3',5,5'-tetraisopropylbiphenyl, 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenol, 1,3,5-tris(3,5 -di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 6,6'-di-tert-butyl-4,4'-butylidene-m-cresol, 4,4',4''-(1-methylpropanyl-3-ylidene)tris(6-tert-butyl-m-cresol), octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, ethylene bis(oxyethylene)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzylmethyl)-2,4,6-trimethylbenzene, 1,3,5-tris[(4-tert-butyl-3-hydroxy-2,6-dimethylphenyl)methyl]-1,3,5-triazine-2,4,6-trione, N,N'-(hexane-1,6-di yl)bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide], benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-C7-C9-branched alkyl ester, 2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazin-2-ylamino)phenol, bis[3,3-bis(4'-hydroxy-3'-tert-butylphenyl)-butanoic acid] glycol ester, bis(1,2,2,6,6-pentamethyl-4-piperidyl)butyl(3,The first group consisting of N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, pentaerythritol tetrakis(2-mercaptoacetate), dioctadecyl sulfide, tris[2-tert-butyl-5-methyl-4- Thio-5'-tert-butyl'-4'-hydroxy-2-methylphenyl]phenyl phosphite, 2,2-bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diylbis[3-(dodecylthio)propionate], di(tridecyl) 3,3'-thiodipropionate, 2-mercaptobenzimidazole, and 3-{3-[(3-sulfanylpropanoyl)oxy]-2,2-bis({[(3-sulfanylpropanoyl)oxy]methyl})propoxy}-2,2 a second group consisting of tetrakis(2,4-di-t-tolylphosphine), bis({[(3-sulfanylpropanoyl)oxy]methyl})propyl 3-sulfanylpropanoate, triphenyl phosphite, tri-o-tolyl phosphite, tri-p-tolyl phosphine, methyldiphenylphosphine, ethyldiphenylphosphine, triphenylphosphine, tri(p-tolyl)phosphine, tris(4-fluorophenyl)phosphine, bis(diphenylphosphino)methane, diphenyl-1-pyrenylphosphine, and tetrakis(2,4-di-t-tolylphosphine). the third group consisting of 2-hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide and N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine; the fourth group consisting of propanedioic acid, [(4-methoxyphenyl)-methylene]-bis(1,2,2,6,6-pentamethyl-4-piperidinyl) ester, 2,2,4,4-tetramethyl-21-oxo-7-oxa-3,20-diazadispiro[5.1.11.2]-heneicosane-20-propanoic acid dodecyl ester / tetradecyl ester, 2,2,6,The primer according to claim 9, which is at least one compound selected from a fifth group consisting of an ester of 6-tetramethyl-4-piperidinol and a higher fatty acid, 2,2,6,6-tetramethylpiperidine, 2,2,6,6-tetramethylpiperidine 1-oxyl free radical, and 4-amino-2,2,6,6-tetramethylpiperidine, or a derivative thereof.

12. The additive is pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2-methyl-4,6-bis[(n-octylthio)methyl]phenol, 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis(6-tert-butyl-p-cresol), 4,4'-dihydroxy-3,3',5,5'-tetraisopropylbiphenyl, 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenol, 1,3,5-tris(3,5 -di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 6,6'-di-tert-butyl-4,4'-butylidene-m-cresol, 4,4',4''-(1-methylpropanyl-3-ylidene)tris(6-tert-butyl-m-cresol), octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, ethylene bis(oxyethylene)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzylmethyl)-2,4,6-trimethylbenzene, 1,3,5-tris[(4-tert-butyl-3-hydroxy-2,6-dimethylphenyl)methyl]-1,3,5-triazine-2,4,6-trione, N,N'-(hexane-1,6-di yl)bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide], benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-C7-C9-branched alkyl ester, 2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazin-2-ylamino)phenol, bis[3,3-bis(4'-hydroxy-3'-tert-butylphenyl)-butanoic acid] glycol ester, bis(1,2,2,6,6-pentamethyl-4-piperidyl)butyl(3,The first group consisting of N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, pentaerythritol tetrakis(2-mercaptoacetate), dioctadecyl sulfide, tris[2-tert-butyl-5-methyl-4- Thio-5'-tert-butyl'-4'-hydroxy-2-methylphenyl]phenyl phosphite, 2,2-bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diylbis[3-(dodecylthio)propionate], di(tridecyl) 3,3'-thiodipropionate, 2-mercaptobenzimidazole, and 3-{3-[(3-sulfanylpropanoyl)oxy]-2,2-bis({[(3-sulfanylpropanoyl)oxy]methyl})propoxy}-2,2 a second group consisting of tetrakis(2,4-di-t-tolylphosphine), bis({[(3-sulfanylpropanoyl)oxy]methyl})propyl 3-sulfanylpropanoate, triphenyl phosphite, tri-o-tolyl phosphite, tri-p-tolyl phosphine, methyldiphenylphosphine, ethyldiphenylphosphine, triphenylphosphine, tri(p-tolyl)phosphine, tris(4-fluorophenyl)phosphine, bis(diphenylphosphino)methane, diphenyl-1-pyrenylphosphine, and tetrakis(2,4-di-t-tolylphosphine). the third group consisting of 2-hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide and N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine; the fourth group consisting of propanedioic acid, [(4-methoxyphenyl)-methylene]-bis(1,2,2,6,6-pentamethyl-4-piperidinyl) ester, 2,2,4,4-tetramethyl-21-oxo-7-oxa-3,20-diazadispiro[5.1.11.2]-heneicosane-20-propanoic acid dodecyl ester / tetradecyl ester, 2,2,6,The coating agent for primer according to claim 10, which is at least one compound selected from Group 5 consisting of esters of 6-tetramethyl-4-piperidinol and higher fatty acids, 2,2,6,6-tetramethylpiperidine, 2,2,6,6-tetramethylpiperidine 1-oxyl free radical, and 4-amino-2,2,6,6-tetramethylpiperidine, or a derivative thereof.

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