JP2023134118A - Carbon ink, electronic component, and manufacturing method for the same - Google Patents

Abstract

To provide a carbon ink capable of forming thin conductive wiring by screen printing, an electronic component using the same, and a manufacturing method for the same.SOLUTION: A carbon ink includes one or more types of carbon particles, polyvinylpyrrolidone, and a solvent. The carbon particles preferably include graphite and carbon black. The total content of the carbon particles is preferably 15 to 40 mass% with respect to the total mass of the carbon ink. The content of polyvinylpyrrolidone is preferably 1 to 25 mass%. The solvent content is preferably 30 to 75 mass%.SELECTED DRAWING: None

Description

The present invention relates to a carbon ink, an electronic component, and a manufacturing method thereof.

Conventionally, conductive pastes in which conductive particles such as metals and carbon are dispersed in dispersants have been used for forming electrodes and electronic circuits, through-hole connections on printed wiring boards, crossovers in printed wiring, mounting semiconductor elements, heat sinks, etc. It is used in a wide variety of applications such as bonding heat dissipating materials. For example, wiring and electrodes can be formed by applying or printing a conductive paste onto various base materials to form a conductive coating film, and then heating and drying and curing the film.

Patent Document 1 discloses a conductive paste containing metal particles, a fatty acid ester as a lubricant, and a thermosetting resin such as an epoxy resin or an acrylic resin. It is said that by pulverizing metal particles to improve their dispersibility and adding a lubricant to prevent agglomeration of metal particles, it is possible to form wiring and the like with excellent conductivity.

Patent Document 2 discloses a method for forming a conductive circuit using a conductive paste containing coated metal particles in which the surface of a metal core particle is coated with carbon, a binder resin, and an organic solvent. Since the metal core particles are coated with carbon, oxidation of the metal is suppressed and migration of metal components can be prevented.

Japanese Patent Application Publication No. 2007-265802 Japanese Patent Application Publication No. 2018-022755

However, when metal particles are used as the main conductor as disclosed in Patent Document 1, oxidation of the metal particles occurs and the conductivity decreases, or migration of metal components occurs and short circuits between wirings occur. There are concerns that this will happen. Furthermore, coating metal core particles with carbon as disclosed in Patent Document 2 increases costs, and there is a concern that this may not be accepted by users.

The present invention provides a carbon ink that allows thin conductive wiring to be formed by screen printing, an electronic component using the carbon ink, and a method for manufacturing the same.

[1] Carbon ink containing one or more types of carbon particles, polyvinylpyrrolidone, and a solvent.
[2] The carbon ink according to [1], wherein the carbon particles include graphite and carbon black.
[3] The carbon ink according to [1] or [2], wherein the total content of the carbon particles is 15 to 40% by mass with respect to the total mass of the carbon ink.
[4] The carbon ink according to any one of [1] to [3], wherein the content of the polyvinylpyrrolidone is 1 to 25% by mass with respect to the total mass of the carbon ink.
[5] The carbon ink according to any one of [1] to [4], wherein the content of the solvent is 30 to 75% by mass with respect to the total mass of the carbon ink.
[6] Any of [1] to [5], wherein the solvent is one or more selected from ion-exchanged water, ethylene glycol, 2-ethylhexanol, dimethyl sulfoxide, ethanol, and N-methyl-2-pyrrolidone. The carbon ink described in item (1) above.
[7] The carbon ink according to any one of [1] to [6], further comprising a polycarbonate resin.
[8] The carbon ink according to any one of [1] to [7], further comprising an isocyanate and a polyol resin.
[9] Manufacture of an electronic component comprising the step of forming one or more conductive wirings made of the cured carbon ink according to any one of [1] to [8] on a base material by screen printing. In the method, the conductive wiring forms a line-and-space conductive pattern arranged parallel to each other on the base material, and the line width of at least one conductive wiring constituting the conductive pattern is 0.05 to 0.05. 0.20 mm, and the width of at least one space constituting the conductive pattern is 0.05 to 0.20 mm.
[10] An electronic component comprising a base material and a conductive layer formed on the base material, wherein the conductive layer is formed by curing the carbon ink according to any one of [1] to [8]. Electronic components made of objects.

The carbon ink of the present invention can be used in the same manner as conventional conductive pastes, and can form conductive wiring and the like that exhibit good conductivity even without containing metal particles. Furthermore, a high-definition conductive pattern (for example, an L/S pattern) can be formed by screen printing. Further, since carbon particles have excellent weather resistance and chemical resistance, conductive wiring and the like formed using the carbon ink of the present invention have excellent weather resistance and chemical resistance.
According to the method for manufacturing an electronic component of the present invention, an electronic component having a high-definition L/S pattern can be easily manufactured by screen printing carbon ink on a base material.

The present invention is considered to contribute to SDGs Goal 12, "Responsible Production and Responsible Consumption."

This is a measurement result confirming that the carbon ink of Example 4 is in a gel state. This is a measurement result confirming that the carbon ink of Example 5 is in a gel state. This is a measurement result confirming that the carbon ink of Example 6 is in a gel state. These are measurement results confirming that the carbon ink of Comparative Example 1 is in a liquid state. These are measurement results confirming that the carbon ink of Comparative Example 2 is in a liquid state.

≪Carbon ink≫
A first aspect of the invention is a carbon ink that includes one or more types of carbon particles, polyvinylpyrrolidone (PVP), and a solvent.

[Carbon particles]
The carbon particles included in the carbon ink of this embodiment are particles made of a carbon material in which at least the center of the particle is formed by bonds between carbon atoms. Any functional group may be added to the surface or part of the carbon particles. Furthermore, the surface or part of the carbon particles may be treated with any chemical modification. The content of carbon based on the total mass of the carbon particles is preferably 90 to 100% by mass, more preferably 95 to 100% by mass, and even more preferably 99 to 100% by mass. In general, a material consisting only of carbon (containing no substantial impurities) is called a carbon material. The carbon particles included in this embodiment are preferably a carbon material.

Suitable carbon particles included in this embodiment include, for example, graphite, carbon black, fullerene, carbon nanotubes, graphene, and the like. Among these, it is preferable to include at least graphite and carbon black. Graphite and carbon black have stable quality, and the particle size, agglomeration state of particles, surface properties (functional groups), etc. can be controlled relatively easily.

The graphite may be either artificial graphite or natural graphite. Examples of natural graphite include flaky graphite, lumpy graphite, and earthy graphite. The particle size of graphite is, for example, about 1 μm to 900 μm. From the viewpoint of enabling high-definition printing using the carbon ink of this embodiment, the average particle diameter of graphite is preferably 5 to 30 μm, more preferably 6 to 15 μm, and even more preferably 7 to 9 μm. Here, the average particle size of graphite is the volume-based median diameter (D ₅₀ ) of the equivalent sphere diameter measured by laser diffraction.

Carbon black is distinguished from graphite in that it does not have the macrocrystalline structure that graphite generally has. Examples of carbon black include furnace black, channel black, acetylene black, thermal black, and hollow shell Ketjen black. The primary particle size of carbon black is, for example, about 1 nm to 500 nm. Usually, carbon black particles aggregate with each other. From the viewpoint of enabling high-definition printing using the carbon ink of this embodiment, the average primary particle diameter of carbon black is preferably 5 to 200 nm, preferably 10 to 100 nm, and more preferably 20 to 50 nm. Here, the average primary particle diameter of carbon black is determined by observing dried carbon black with an electron microscope and measuring the longest length of randomly selected primary particles as the particle diameter. shall be the arithmetic mean value of the measured values.

The total content of the carbon particles relative to the total mass of the carbon ink of this embodiment is, for example, preferably 15 to 40% by mass, more preferably 20 to 36% by mass, and even more preferably 22 to 33% by mass.
When it is at least the lower limit of the above range, it is possible to suppress blurring when printing the carbon ink of the present embodiment and improve the conductivity of the conductive wiring made of the carbon ink coating.
When it is below the upper limit of the above range, the carbon ink of this embodiment can be printed with high definition and a conductive pattern with a narrow line width and a narrow pitch can be formed.

The content of graphite relative to the total mass of the carbon ink of this embodiment is, for example, preferably 10 to 35% by mass, more preferably 15 to 30% by mass, and even more preferably 20 to 25% by mass.
When it is at least the lower limit of the above range, it is possible to suppress blurring when printing the carbon ink of the present embodiment and improve the conductivity of the conductive wiring made of the carbon ink coating.
When it is below the upper limit of the above range, the carbon ink of this embodiment can be printed with high definition and a conductive pattern with a narrow line width and a narrow pitch can be formed.

The content of carbon black relative to the total mass of the carbon ink of this embodiment is, for example, preferably 1 to 20% by mass, more preferably 3 to 15% by mass, and even more preferably 5 to 10% by mass.
When it is at least the lower limit of the above range, it is possible to suppress blurring when printing the carbon ink of the present embodiment and improve the conductivity of the conductive wiring made of the carbon ink coating.
When it is below the upper limit of the above range, the carbon ink of this embodiment can be printed with high definition and a conductive pattern with a narrow line width and a narrow pitch can be formed.

In the carbon ink of this embodiment, the content of graphite is preferably greater than the content of carbon black. From the viewpoint of easily realizing this relationship, it is preferable that the carbon black is Ketjenblack.

[PVP]
The content of polyvinylpyrrolidone (PVP) with respect to the total mass of the carbon ink of this embodiment is, for example, preferably 1 to 25% by mass, more preferably 2 to 20% by mass, even more preferably 3 to 15% by mass, and 5 to 10% by mass. % by weight is most preferred.
When it is at least the lower limit of the above range, it is possible to suppress blurring when printing the carbon ink of the present embodiment and improve the conductivity of the conductive wiring made of the carbon ink coating.
When it is below the upper limit of the above range, the carbon ink of this embodiment can be printed with high definition and a conductive pattern with a narrow line width and a narrow pitch can be formed.

The K value of PVP included in this embodiment is preferably 50 or more, more preferably 80 or more, even more preferably 90 or more, even more preferably 100 or more, particularly preferably 110 or more, and most preferably 120 or more. The upper limit of the K value is usually 200 or less, preferably 160 or less.
Within the above preferred range, the carbon ink of this embodiment can exhibit viscoelasticity with excellent printability. Generally, the K value is known as a viscosity characteristic value that correlates with molecular weight, and is calculated by applying the relative viscosity value (at 25° C.) to water measured by a capillary viscometer to the Fikentscher equation. The formula and measurement method are specified in ISO 1628-1:1998(E).

[solvent]
The solvent included in this embodiment is preferably one that has excellent compatibility with PVP. For example, it is preferable to use an organic solvent that can dissolve PVP at a concentration of 10% by mass or more at 20 to 25°C. Examples of such organic solvents include methanol, ethanol, propanol, isopropanol, butanol, secondary butanol, amyl alcohol, 2-ethyl-hexanol, cyclohexanol, phenol, ethylene glycol, 1,3-butanediol, 1, 4-butanediol, glycerin, diacetone alcohol, formic acid, acetic acid, propionic acid, glycol ether, diethylene glycol, triethylene glycol, hexamethylene glycol, polyethylene glycol 400, 2,2-thiodiethanol, γ-butyrolactone, ethyl lactate, methyl Cyclohexanone, dichloromethane, dichloroethane, chloroform, 2-pyrrolidone, N-methyl-2-pyrrolidone (NMP), N-vinyl-2-pyrrolidone, butylamine, cyclohexylamine, aniline, ethylenediamine, pyridine, morpholine, 2-aminoethanol, diethanolamine , triethanolamine, aminoethylethanolamine, 2-hydroxyethylmorpholine, 2-amino-2-methyl-1-propanol, nitromethane, nitroethane, dimethyl sulfoxide and the like. Moreover, water may be contained as a solvent. The number of solvents included in this embodiment may be one, or a mixture of two or more.

Among the above solvents, one or more solvents selected from ion-exchanged water (DW), ethylene glycol, 2-ethylhexanol, dimethyl sulfoxide (DMSO), ethanol, and NMP are particularly preferred. A mixed solution of DW and DMSO is also particularly preferable, and the mixing ratio thereof is preferably DW:DMSO=0.5:1.5 to 1.5:0.5, and 0.8:1.2 to 1.2 on a volume basis. ~0.8 is more preferred, and 0.9:1.1 ~ 1.1:0.9 is even more preferred.
These particularly preferred solvents not only dissolve PVP well, but also gel when mixed with PVP, giving the carbon ink of this embodiment viscosity and making it gel-like. As a result, the coatability and printability of the carbon ink of this embodiment are improved, fading is suppressed, and a conductive pattern with a narrow line width and a narrow pitch can be easily formed.

The content of the solvent relative to the total mass of the carbon ink of this embodiment is, for example, preferably 30 to 75% by mass, more preferably 40 to 70% by mass, and even more preferably 50 to 65% by mass.
When it is at least the lower limit of the above range, it is possible to suppress blurring when printing the carbon ink of the present embodiment and improve the conductivity of the conductive wiring made of the carbon ink coating.
When it is below the upper limit of the above range, the carbon ink of this embodiment can be printed with high definition and a conductive pattern with a narrow line width and a narrow pitch can be formed.

[viscosity]
The viscosity of the carbon ink of this embodiment is preferably 20 to 200 P at 23°C. Here, the viscosity is the value measured 120 seconds after the rotor was rotated at 50 rpm using an E-type viscometer.

[Polycarbonate resin]
The carbon ink of this embodiment preferably contains one or more polycarbonate resins. Carbon ink containing polycarbonate resin tends to maintain the shape of a coating film applied onto a substrate. Therefore, it becomes easy to form a high-definition conductive pattern that reflects high-definition printing. Polycarbonate resin is preferred because it has high compatibility with PVP and high dispersibility in the solvents that easily dissolve PVP. In particular, since polycarbonate resin has excellent dispersibility in PVP and NMP, when NMP is used as the solvent, it is preferable that polycarbonate resin is also blended.

From the viewpoint of enhancing the above effects, the viscosity average molecular weight of the polycarbonate resin is preferably 14,000 to 26,000, more preferably 16,000 to 24,000, and 18,000 to 22,000. is even more preferable. Here, the viscosity average molecular weight is determined by measuring the flow time of a solution dissolved in toluene or methyl ethyl ketone at a concentration of 15% by mass using a capillary viscometer at 25°C, determining the intrinsic viscosity [η], and calculating the intrinsic viscosity [η]. This is a value calculated from the formula [η]=KM ^a .

From the viewpoint of enhancing the above effects, the glass transition temperature Tg of the polycarbonate resin is preferably 140 to 220°C, more preferably 155 to 200°C, and even more preferably 170 to 190°C. Here, Tg is a value measured by the method of JIS K 7121.

The content of the polycarbonate resin relative to the total mass of the carbon ink of this embodiment is preferably 1 to 10% by mass, more preferably 2 to 8% by mass, and even more preferably 3 to 6% by mass, from the viewpoint of enhancing the above effects.

[Isocyanate and polyol resin]
The carbon ink of this embodiment preferably contains one or more isocyanates and one or more polyol resins. The structural strength of the conductive layer formed by drying and curing the carbon ink coating applied to the base material can be increased.

The isocyanate preferably has two or more isocyanate groups in the molecule. When it has a plurality of isocyanate groups, it reacts with the hydroxyl group of the polyol resin to form a urethane bond, and also crosslinks the polyol resins, thereby making it possible to further increase the structural strength of the conductive layer. The isocyanate group may be modified with a protective group that is removed by heat, ultraviolet rays, or the like. That is, the isocyanate may be a block type isocyanate.
Further, the isocyanate preferably has an aromatic cyclic group or an aliphatic cyclic group in the molecule. Isocyanate having a cyclic group in its molecule can further enhance the structural strength of the conductive layer.

Specifically preferred isocyanates include, for example, xylene diisocyanate (XDI), 1,4-bis(isocyanatomethyl)cyclohexane (H6XDI), 1,5-pentamethylene diisocyanate (PDI), and 1,6-hexamethylene diisocyanate (HDI). ), isophorone diisocyanate (IPDI), toluene diisocyanate (TDI), and their isocyanurates, biurets, allophanates, and trimethylolpropane (TMP) adducts. Another example is block polyisocyanate sold as the Bronate (registered trademark) series manufactured by Taiei Sangyo Co., Ltd.

Polyol resin is a polymer having multiple hydroxyl groups in its molecule. Its hydroxyl value is, for example, 120 to 180 KOHmg/g. Examples of the main chain systems of polyol resins include polyester systems, polyether systems, polycarbonate systems, and the like.

The total content of isocyanate and polyol resin with respect to the total mass of the carbon ink of this embodiment is preferably 1 to 20% by mass, more preferably 2 to 10% by mass, and 3 to 8% by mass from the viewpoint of enhancing the above effects. is even more preferable.
The blending ratio of isocyanate and polyol resin may be appropriately set in consideration of the NCO equivalent and the OH equivalent calculated from the hydroxyl value.

A catalyst that promotes the reaction between the isocyanate and the polyol resin may be added to the carbon ink of this embodiment. The type of catalyst is not particularly limited, and any known catalyst that catalyzes urethane bonding can be used. Examples include organometallic complexes such as dibutyltin didodecanoate, zinc octylate, tin octylate, cobalt naphthenate, zinc naphthenate, iron acetylacetonate, and metal salts such as aluminum chloride, tin chloride, and zinc chloride. The blending amount is adjusted as appropriate.

≪Manufacturing method of electronic components≫
A second aspect of the present invention is a method for manufacturing an electronic component, comprising the step of forming one or more conductive wirings made of the cured carbon ink of the first aspect on a base material by screen printing (stencil printing). be.

The base material used in this embodiment is not particularly limited, and examples thereof include substrates for electronic components, films, and the like. Examples of materials constituting the base material include polyester resins such as polyethylene terephthalate, polylactic acid, and polyethylene naphthalate, polyolefin resins such as polyethylene, polypropylene, polystyrene, ethylene vinyl acetate, and cyclic olefin copolymers, vinyl resins, polycarbonates, and polyamides. , polyimide, acrylic resin, cellulose resin, polyurethane, silicone rubber, polyvinyl chloride, polyvinyl fluoride, and other synthetic resins. In addition, paper, cloth, glass, ceramics, etc. may be used.

A conventional method can be applied to the screen printing performed in this embodiment. For example, a plate film is layered on a screen with appropriate openings to create a plate that closes off the lines other than the lines to be printed, carbon ink is placed on this plate, and a rubber spatula called a squeegee is used to apply the carbon ink to the plate. Move while applying pressure. This allows the carbon ink to pass through the screen where the printing plate is open and be pushed out onto the surface of the base material placed under the printing plate, allowing printing to be performed.

The opening of the screen used in screen printing is expressed as (mesh pitch) - (wire diameter). In general, narrower apertures enable high-definition printing, but place stricter demands on the ink. Since the carbon ink used in this embodiment has carbon particles highly dispersed in PVP and a solvent, a screen with a narrow opening can be used. The opening of screen printing in this embodiment can be 100 μm or less, 50 μm or less is also possible, and 20 to 40 μm is preferable.

By screen printing in this embodiment, a line-and-space conductive pattern (L/S pattern) in which one or more conductive wirings are arranged in parallel to each other can be formed on a base material. At this time, the line width of at least one part of the conductive wiring constituting the L/S pattern is 0.05 to 0.20 mm, and the space width of at least one part of the L/S pattern is 0.05 to 0. .20mm. To make it more precise, the line width of at least one part of the conductive wiring constituting the L/S pattern is 0.05 to 0.15 mm, and the space width of at least one part constituting the L/S pattern is 0.05 mm. ~0.15mm.

In the L/S pattern, a location where the line width is within the above range and a location where the space width is within the above range may be the same location or may be different locations. For example, the space width at the location where the first conductive wiring and the second conductive wiring are adjacent to each other is within the above range, and at least one of the first conductive wiring and the second conductive wiring at the location where the space width was measured. The width may be within the above range.

Note that a plurality of conductive wires forming the L/S pattern may be connected to a common terminal, or a single conductive wire may be folded back to form the L/S pattern. However, in the L/S pattern, it is important that the parts that should originally be connected as line parts are not frayed and disconnected, and the parts that should be separated as space parts are not short-circuited due to thick wires. This is the premise of being.

The surface resistivity of the conductive wiring made of the cured carbon ink of the first embodiment can be 20 to 150 Ω/□ when the line width is 0.90 to 1.10 mm and the thickness is 4 to 10 μm. , preferably 20 to 100Ω/□. Similarly, for example, when the line width is 0.10 to 0.15 mm and the thickness is 4 to 10 μm, it can exhibit 20 to 150 Ω/□, preferably 20 to 120 Ω/□.

≪Electronic parts≫
A third aspect of the present invention is an electronic component comprising a base material and a conductive layer formed on the base material, wherein the conductive layer is formed of a cured product of the carbon ink according to the first aspect. , electronic components. Although the electronic component of the third aspect can be manufactured by the manufacturing method of the second aspect of the present invention, the electronic component of the third aspect may be manufactured by other methods.
The description of the base material is the same as that of the base material of the second embodiment, so duplicate description will be omitted.
The formation range of the conductive layer may be the entirety or a part of any surface of the base material.
When a conductive layer is formed only on a part of the surface of the base material, for example, the conductive layer may be a fine conductive pattern including conductive wiring, conductive circuits, electrodes, etc. The provided area and the non-provided area may be present on the same surface and only roughly divided. The conductive layer may form an L/S pattern on the base material. The conductive layer may be laminated on any other conductive layer, or may be formed as an independent conductive layer on an insulating base material without being laminated on any other conductive layer.

The average thickness of the conductive layer is, for example, preferably 10 nm or more and 100 μm or less, more preferably 20 nm or more and 50 μm or less, and even more preferably 30 nm or more and 30 μm or less.
If the average thickness of the conductive layer is equal to or greater than the lower limit value, high conductivity can be exhibited, and if the average thickness is equal to or less than the upper limit value, the adhesion of the conductive layer to the base material is further improved.
The average thickness of the conductive layer is the value obtained by measuring the thickness at 10 randomly selected locations and averaging the measured values.

The electronic component of this embodiment can constitute various electronic devices, and is suitable for, for example, a capacitive touch sensor, a touch switch, a touch pad, a pressure-sensitive switch, a conductive contact of a push button, and the like.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples.

[Example 1]
<Preparation of carbon ink>
Graphite powder (manufactured by Nippon Graphite Co., Ltd., model number: CSP-E, shape: scaly, average particle size 8 μm) 20% by mass, Ketjen black (manufactured by Lion Specialty Chemicals, model number: Carbon ECP, average primary particle size 30 nm) 6 mass %, PVP (manufactured by Ashland Japan Co., Ltd., model number: K-120, K value = 114-130) 8% by mass, polycarbonate resin (manufactured by Mitsubishi Gas Chemical Co., Ltd., model number: FPC-0220, viscosity average molecular weight 20000, glass transition Temperature Tg = 184°C) 5% by mass, N-methyl-2-pyrrolidone (NMP) (manufactured by Junsei Kagaku Co., Ltd.) 55% by mass, dibutyltin didodecanoate (manufactured by Junsei Kagaku Co., Ltd.) 1% by mass, block type isocyanate (Daei Kagaku Co., Ltd.) Mixed at a blending ratio of 3% by mass of Bronate 1901 (manufactured by Sangyo Co., Ltd., aromatic ring containing type) and 2% by mass of polyester polyol resin (manufactured by Tosoh Corporation, model number: Nipporan 131, hydroxyl value = 142-160 KOHmg/g). , carbon ink was obtained.

<Formation of L/S pattern>
The printing plate on which the L/S pattern was drawn was set on a screen with an opening of 35 μm, and the carbon ink prepared above was screen printed on the PET film (on the base material) using a screen printing machine. This was dried and cured at 150° C. for 15 to 30 minutes to form an L/S pattern on the base material. The wiring pitches in Tables 1 to 3 are the total value of the line width (conductive wiring width) of the plate film used: space width = 1:1. In other words, a wiring pitch of 2.0 mm means printing with a plate having a line width of 1.0 mm and a space width of 1.0 mm. Line widths (line widths) at three points randomly selected from the L/S pattern formed on the base material were measured using a digital microscope. The average values are shown in Table 1. Furthermore, the thickness and length of the line were measured, and the surface resistivity (unit: Ω/□) was measured using a two-terminal method using a resistance meter (manufactured by ADVANTEST, model number: R6551). The results are shown in Table 2.
Screen printing was performed continuously on 10 sheets of substrate (continuous printing without cleaning the screen or plate film), and there was no disconnection due to fading on the 10th sheet printing, and there was no short circuit due to thick lines. It did not occur. This good result was noted in Table 1 as continuous printing "OK".

[Example 2]
Same as Example 1 except that polycarbonate resin (manufactured by Mitsubishi Gas Chemical Co., Ltd., model number: PCZ-200, viscosity average molecular weight 21500, glass transition temperature Tg = 174°C) was used instead of polycarbonate resin (FPC-0220). A carbon ink was prepared and an L/S pattern was formed. The results are listed in Tables 1 and 2.

[Example 3]
Same as Example 1 except that polycarbonate resin (manufactured by Mitsubishi Gas Chemical Co., Ltd., model number: FPC-8225, viscosity average molecular weight 20000, glass transition temperature Tg = 156°C) was used instead of polycarbonate resin (FPC-0220). A carbon ink was prepared and an L/S pattern was formed. The results are listed in Tables 1 and 2.

[Example 4]
A carbon ink was prepared in the same manner as in Example 1, except that no polycarbonate resin was added, the amount of PVP was increased to 12% by mass, and the amount of NMP as a solvent was increased to 56% by mass. /S pattern was formed. The results are listed in Tables 1 and 2.

[Example 5]
Carbon ink was applied in the same manner as in Example 1, except that graphite powder (manufactured by Ito Graphite Industries Co., Ltd., model number: CP2000M, clay-like, average particle size 3.49 μm) was used instead of graphite powder (CSP-E). An L/S pattern was formed. The results are listed in Tables 1 and 2.

[Example 6]
The amount of graphite powder (CSP-E) was increased to 23% by mass, the amount of Ketjen black (carbon ECP) was increased to 7% by mass, the amount of PVP was decreased to 5% by mass, and the amount of polycarbonate resin was increased to 23% by mass. A carbon ink was produced in the same manner as in Example 1, except that ethylene glycol as a solvent was not blended, NMP was not blended, 65% by mass of ethylene glycol was blended, and dibutyltin didodecanoate, isocyanate, and polyol resin were not blended. An L/S pattern was formed. The results are listed in Tables 1 and 2.

[Comparative example 1]
The blending amount of graphite powder (CSP-E) was reduced to 18% by mass, the blending amount of Ketjen black (carbon ECP) was reduced to 5% by mass, PVP was not blended, polycarbonate resin was not blended, polyester Resin (manufactured by Toyobo STC, model number: Vylon E712, hydroxyl value = 6 to 21 KOHmg/g, solid content 32% by mass, solvent: carbitol acetate) is blended with 18% by mass, no NMP is blended, and the solvent diethylene glycol mono A carbon ink was prepared in the same manner as in Example 1, except that 53% by mass of ethyl ether acetate was blended, and an L/S pattern was formed. The results are listed in Table 3.

[Comparative example 2]
The amount of graphite powder (CSP-E) was reduced to 18% by mass, the amount of Ketjen black (carbon ECP) was reduced to 5% by mass, and polycarbonate resin (FPC-0220) was used without PVP. A carbon ink was prepared in the same manner as in Example 1, except that the amount was increased to 18% by mass, and the amount of NMP as a solvent was decreased to 53% by mass, and an L/S pattern was formed. The results are listed in Table 3.

[Comparative example 3]
The blending amount of graphite powder (CSP-E) was reduced to 18% by mass, the blending amount of Ketjen black (carbon ECP) was reduced to 5% by mass, no PVP was blended, no polycarbonate resin was blended, and polyamide 18% by mass of resin (manufactured by Toyobo STC, model number: HR-11NN, number average molecular weight 20000, glass transition temperature Tg 300°C, solid content 15% by mass, solvent: NMP) was blended, and the NMP of the solvent was reduced to 53% by mass. A carbon ink was prepared in the same manner as in Example 1 except that it was blended, and an L/S pattern was formed. The results are listed in Table 3.

[Comparative example 4]
The blending amount of graphite powder (CSP-E) was reduced to 18% by mass, the blending amount of Ketjen black (carbon ECP) was reduced to 5% by mass, no PVP was blended, no polycarbonate resin was blended, and polyvinyl Carbon ink was prepared in the same manner as in Example 1, except that 18% by mass of alcohol (manufactured by Japan Vinyl Poval Co., Ltd., model number: JMR-10LL) was blended, and the amount of NMP as a solvent was reduced to 53% by mass. Then, an L/S pattern was formed. The results are listed in Table 3.

From the above results, it is clear that the carbon inks of Examples containing PVP have excellent printing characteristics that enable continuous printing even at narrow pitches. On the other hand, the carbon ink of the comparative example that did not contain PVP caused defects such as line thickening and fading, and it was difficult to form a narrow pitch L/S pattern.

<Evaluation of fluidity of carbon ink>
The carbon inks produced in Examples 1 to 6 were in a gel state when observed with the naked eye and felt to the touch. On the other hand, the carbon inks produced in Comparative Examples 1 to 4 were not in a gel state. Here, in order to accurately evaluate whether the manufactured carbon ink is in a gel state, Examples 4 to 6 and Comparative Examples 1 to 2 were used as samples, and storage modulus G', loss modulus G'', and its loss tangent tan δ (G''/G') using a commercially available rheometer (manufactured by TA Instruments Japan Co., Ltd., model number: Discovery HR-10) and a cone plate (CONE SST 20MM 2DEG SMART-SWAP HRx0). ). The measurement conditions were a temperature of 23° C. and a frequency of 10 ⁻¹ to 10 ² Hz. The results are shown in Figures 1-5. In FIGS. 1 to 5, the left vertical axis represents the storage modulus G' and the loss modulus G'', and the right vertical axis represents the loss tangent tan δ.

From the graphs in Figures 1 to 5, it can be seen that in Examples 4 to 6, G'>G'' in the entire frequency range of 10 ^-1 to 10 ² Hz, and the lines connecting the plots of G' and G'' do not intersect. , it was clearly shown that it was in a gel state. On the other hand, in Comparative Examples 1 and 2, G'<G'' in the above frequency range, clearly indicating a non-gel state, that is, a liquid state.

From the above results, the following conclusions were obtained. That is, since the carbon ink of the example according to the present invention is in a gel state, a high-definition L with a printed wiring pitch of 0.2 mm (screen printing using a printing plate with a line width of 0.1 mm and a space width of 0.1 mm) /S pattern could be printed continuously. On the other hand, since the carbon ink of the comparative example was not in a gel state, it was not possible to continuously print a high-definition L/S pattern as in the example.

Claims (10)

A carbon ink containing one or more types of carbon particles, polyvinylpyrrolidone, and a solvent. The carbon ink according to claim 1, wherein the carbon particles include graphite and carbon black. The carbon ink according to claim 1 or 2, wherein the total content of the carbon particles is 15 to 40% by mass with respect to the total mass of the carbon ink. The carbon ink according to any one of claims 1 to 3, wherein the content of the polyvinylpyrrolidone is 1 to 25% by mass based on the total mass of the carbon ink. The carbon ink according to any one of claims 1 to 4, wherein the content of the solvent is 30 to 75% by mass based on the total mass of the carbon ink. According to any one of claims 1 to 5, the solvent is one or more selected from ion-exchanged water, ethylene glycol, 2-ethylhexanol, dimethyl sulfoxide, ethanol, and N-methyl-2-pyrrolidone. carbon ink. The carbon ink according to any one of claims 1 to 6, further comprising a polycarbonate resin. The carbon ink according to any one of claims 1 to 7, further comprising an isocyanate and a polyol resin. A method for manufacturing an electronic component, comprising the step of forming one or more conductive wirings made of the cured carbon ink according to any one of claims 1 to 8 on a base material by screen printing,
The conductive wiring forms a line-and-space conductive pattern arranged parallel to each other on the base material, and the line width of at least one conductive wiring constituting the conductive pattern is 0.05 to 0.20 mm. . A method of manufacturing an electronic component, wherein the width of at least one space constituting the conductive pattern is 0.05 to 0.20 mm. An electronic component comprising a base material and a conductive layer formed on the base material, the conductive layer being formed of a cured product of the carbon ink according to any one of claims 1 to 8. There are electronic parts.

Images