Ni paste for gravure printing, and method for manufacturing electronic component

Abstract

The purpose of the present disclosure is to provide a Ni paste which is for use in gravure printing and in which separation of dielectric particles is suppressed. A Ni paste according to the present disclosure includes Ni particles, dielectric particles, a binder resin, a solvent, and a dispersant. The Ni paste includes at least 35 wt% of the Ni particles with respect to the entire Ni paste, and the ratio (dielectric particles / Ni particles) of the weight (wt%) of the dielectric particles to the weight (wt%) of the Ni particles is at least 0.05. The Ni paste is characterized in that, when 0.5 g of a diluted paste obtained by diluting the Ni paste to a solid concentration of 20 wt% is subjected to centrifugal sedimentation treatment under a prescribed condition, the ratio of the weight Wb(mg) of the dielectric particles included in 0.3 g of a supernatant liquid of the diluted paste obtained after the centrifugal sedimentation treatment, the weight being measured by inductively coupled plasma optical emission spectrometry, to the weight Wa(mg) of the dielectric particles included in 0.5 g of the diluted paste is at most 13%.

Description

Ni paste for gravure printing, and method for manufacturing electronic components

[0001] The present invention relates to a Ni paste for gravure printing and a method for manufacturing electronic components. This international application claims priority to Japanese Patent Application No. 2025-55098, filed on 28 March 2025, and the entire contents of that application are incorporated herein by reference.

[0002] In the manufacture of electronic components, a widely used method involves applying an internal electrode-forming paste containing conductive particles and dielectric particles to a substrate to form a coating film, and then firing it to form an electrode layer. Examples of such internal electrode-forming pastes include Ni paste containing Ni particles as conductive particles, a binder resin, and dielectric particles (ceramic material). An example of such a Ni paste is Japanese Patent Application Publication No. 2023-070182.

[0003] Incidentally, with the increasing performance of various electronic devices, there is a growing demand for thinner, smaller, and higher-density electronic components mounted on these devices. For example, in multilayer ceramic capacitors (MLCCs), there is a need to increase capacitance while reducing the volume of the MLCC by thinning the thickness of each layer of the internal electrode layer and increasing the number of layers. For these reasons, gravure printing is increasingly being used instead of screen printing for applying paste for forming the internal electrode layer. Gravure printing offers superior productivity due to its faster printing speed compared to screen printing, and it can form thin films with stable quality. An example of such a gravure printing paste is, for example, Japanese Patent Application Publication No. 2012-174797.

[0004] Japanese Patent Application Publication No. 2023-070182 Japanese Patent Application Publication No. 2012-174797

[0005] However, when Ni paste containing dielectric particles is applied to gravure printing applications, separation (lifting) of the dielectric particles in the Ni paste may occur. When a coating film is formed using Ni paste in which the dielectric particles have separated, it is difficult to form a homogeneous coating film, which may lead to a decrease in yield.

[0006] The technology disclosed herein has been made in view of the circumstances described above, and its main purpose is to provide a Ni paste for use in gravure printing that suppresses the separation of dielectric particles.

[0007] The Ni paste disclosed herein comprises Ni particles, dielectric particles, a binder resin, a solvent, and a dispersant. The Ni paste contains 35 wt% or more of the Ni particles relative to the total Ni paste, and the ratio of the weight (wt%) of the dielectric particles to the weight (wt%) of the Ni particles (dielectric particles / Ni particles) is 0.05 or more. When 0.5 g of the diluted paste, obtained by diluting the Ni paste to a solid content concentration of 20 wt%, is subjected to centrifugal sedimentation under the following conditions: Temperature: 25°C; Rotation speed: 4000 rpm; Processing time: 6200 seconds, the weight W of the dielectric particles contained in 0.5 g of the diluted paste is ａ The weight W of dielectric particles contained in 0.3 g of the supernatant liquid of the diluted paste after the centrifugal sedimentation treatment in inductively coupled plasma atomic emission spectrometry (mg) ｂ It is characterized by having a ratio of 13% or less (mg).

[0008] In order to achieve the above objective, the inventors conducted studies and confirmed that even among Ni pastes with the same raw materials and composition, differences in dielectric separation suppression occur. Based on this perspective, the inventors conducted further intensive studies and found that the W of the above Ni paste ａ W relative to (mg) ｂ We found that the ratio of (mg) serves as an indicator, and that by setting this ratio within a predetermined range, the separation (lifting) of dielectric particles in the Ni paste is suppressed.

[0009] According to this configuration, the W of the Ni paste ａ Wｂ By setting the ratio to 13% or less, the occurrence of separation of dielectric particles in the Ni paste is suitably controlled. Therefore, according to the Ni paste of the present disclosure, it is possible to form a uniform coating film.

[0010] In a preferred embodiment of the Ni paste disclosed herein, the ratio of the weight (wt%) of the dielectric particles to the weight (wt%) of the Ni particles (dielectric particles / Ni particles) is 0.3 or less.

[0011] In a preferred embodiment of the Ni paste disclosed herein, under an environment of 25°C, at a shear rate of 10000 sec －１ the viscosity V of the Ni paste when measured at ｍ is 0.3 Pa·S or less.

[0012] In a preferred embodiment of the Ni paste disclosed herein, the viscosity V ｍ the ratio of the viscosity V of the Ni paste measured at a shear rate of 100 sec －１ measured under an environment of 25°C to the above viscosity V ｈ the ratio (V ｈ / V ｍ ) is 8 or less.

[0013] In a preferred embodiment of the Ni paste disclosed herein, the solvent includes a hydrocarbon-based solvent and an alcohol-based solvent.

[0014] In a preferred embodiment of the Ni paste disclosed herein, the binder resin includes a cellulose-based resin and a polyvinyl acetal-based resin.

[0015] In a preferred embodiment of the Ni paste disclosed herein, the dispersant includes an anionic dispersant and a nonionic dispersant.

[0016] In a preferred embodiment of the Ni paste disclosed herein, the anionic dispersant includes a carboxylic acid-based dispersant.

[0017] In a preferred embodiment of the Ni paste disclosed herein, the dielectric particles include barium titanate.

[0018] In one preferred embodiment of the Ni paste disclosed herein, the Ni paste further comprises a secondary amine compound.

[0019] Furthermore, as another aspect of the technology disclosed herein, a method for manufacturing electronic components is provided. Such a manufacturing method includes applying the Ni paste onto a substrate and firing it. This makes it possible to manufacture electronic components having a homogeneous electrode layer.

[0020] Figure 1 is a schematic cross-sectional view showing the structure of a multilayer ceramic capacitor. Figure 2 is a schematic cross-sectional view showing the structure of an unfired laminate. Figure 3 is an SEM observation image of Ni paste coatings related to Examples 1 to 8. Figure 4 is a conceptual diagram explaining the method for calculating the dispersion index.

[0021] Preferred embodiments of the technology disclosed herein are described below. Matters other than those specifically mentioned herein (e.g., the composition and properties of Ni paste) that are necessary for carrying out the present invention (e.g., the configuration of electronic components) can be carried out based on the technical content taught herein and the common technical knowledge of those skilled in the art. In this specification, the notation "X to Y (where X and Y are arbitrary values)" indicating a numerical range includes not only the meaning of "greater than or equal to X and less than or equal to Y," but also the meanings of "preferably greater than X" and "preferably less than Y."

[0022] <Ni Paste> The Ni paste disclosed herein comprises (A) Ni particles, (B) dielectric particles, (C) binder resin, (D) solvent, and (E) dispersant. In this embodiment, the Ni paste comprises (F) a thickening inhibitor in addition to (A) to (E) above. The Ni paste disclosed herein can be suitably used in gravure printing. In the following description, (A) Ni particles and (B) dielectric particles may be referred to as "inorganic particles".

[0023] In this specification, the term "particle" refers to a collection of numerous particles (microparticles), unless it specifically refers to a single particle. Because the Japanese term is ambiguous regarding singularity or pluralness, the above definition is used to clarify the meaning of "particle (microparticle)."

[0024] In this specification, "coating film" refers to a film-like material (dried product) obtained by drying Ni paste at a temperature lower than the boiling point of (C) binder resin and / or (E) dispersant (typically 200°C or lower, for example 150°C or lower, preferably 120°C or lower). When Ni paste is dried at a temperature below the boiling point of (C) binder resin and / or (E) dispersant, these components may remain in the coating film. The term "coating film" encompasses all unbaked (pre-baked) film-like materials.

[0025] Furthermore, in this specification, "electrode layer" refers to a sintered body (fired product) obtained by firing inorganic particles, such as (A) Ni particles and (B) dielectric particles, after the organic components in the Ni paste, such as (C) binder resin, (D) solvent, and (E) dispersant, have disappeared. The electrode layer includes wiring (linear bodies), wiring patterns, and solid patterns. Each component will be described in order below.

[0026] (A) Ni Particles Ni particles are the main component material of the electrode layer after firing the Ni paste. Ni particles impart electrical conductivity to the electrode properties. In this specification, "Ni particles" refers to particles in which the main element constituting the Ni particle is Ni. That is, in this specification, "Ni particles" is a concept that includes not only particles in which the entire particle is composed of Ni (single Ni particles), but also Ni alloy particles (e.g., nickel-copper (Ni-Cu), nickel-aluminum (Ni-Al), etc.), core-shell particles (e.g., core-shell particles with Ni particles as the core, for example, core-shell particles in which the surface of Ni particles is coated with a precious metal such as silver, etc.). Furthermore, "the main element constituting the Ni particle is Ni" means that among the metallic elements constituting the Ni particle, the metallic element with the highest abundance ratio is Ni.

[0027] The manufacturing method of Ni particles and the properties of the particles constituting the Ni particles, such as particle size and shape, are not particularly limited. The particle size can be appropriately selected depending on the application of the Ni paste and the dimensions of the electrode layer. The particle size should be selected so as to fit within the minimum dimensions of the target electrode layer (e.g., the internal electrode layer), such as thickness and / or width, taking into account the firing shrinkage rate. The average particle diameter D of the Ni particles is not particularly limited. １The particle size may be approximately a few nanometers to a few micrometers, for example, 10 nm to 10 μm. In this specification, "average particle size" refers to the particle size that corresponds to the cumulative 50% of the smallest particle size in the particle size distribution based on electron microscope observation.

[0028] For example, in applications where the internal electrode layer of ultra-small to small MLCCs is formed, the average particle size D of Ni particles is １ However, it may be smaller than the thickness of the internal electrode layer (length in the stacking direction), generally 0.5 μm or less, typically 0.4 μm or less, and preferably 0.3 μm or less. Average particle size D １ If the average particle size D of Ni particles is below a predetermined value, even a thin-film electrode layer can have its surface irregularities kept to a minimum. １ The average particle size D is generally 0.01 μm or larger, typically 0.05 μm or larger, preferably 0.1 μm or larger, for example, 0.15 μm or larger. １ When this value is above a predetermined value, the surface energy of the particles is suppressed, and aggregation in the Ni paste is inhibited. As a result, a more homogeneous coating can be achieved.

[0029] The shape of the Ni particles may be, for example, approximately spherical, flake-shaped, needle-shaped, or irregular. While not particularly limited, for applications forming thin-film electrode layers, the Ni particles may be approximately spherical. This allows for maintaining a low viscosity of the Ni paste, improving the handling properties of the paste and the workability during gravure printing. In this specification, "approximately spherical" refers to a shape that can be generally considered a sphere (ball) overall, with an average aspect ratio of approximately 1 to 2, for example, 1 to 1.5. Furthermore, in this specification, "aspect ratio" refers to the ratio (b / a) of the length of the long side (b) to the length of the short side (a) of a particle when a rectangle is drawn circumscribing the observed image obtained by observing the Ni particles with an electron microscope. The average aspect ratio means the arithmetic mean of the aspect ratios of multiple particles (for example, 100 particles).

[0030] From the viewpoint of providing sufficient electrical conductivity, the Ni particle content is preferably 35 wt% or more, preferably 37.5 wt% or more, preferably 40 wt% or more, preferably 42.5 wt% or more, more preferably 45 wt% or more, and even more preferably 47.5 wt% or more, relative to the total Ni paste (100 wt%). On the other hand, from the viewpoint of the handling properties of the paste and the workability during gravure printing, the upper limit of the Ni particle content is preferably 70 wt% or less, preferably 65 wt% or less, more preferably 60 wt% or less, even more preferably 57.5 wt% or less, even more preferably 55 wt% or less, and particularly preferably 52.5 wt% or less, relative to the total Ni paste.

[0031] Furthermore, metal particles other than Ni particles may be included in the Ni paste, as long as they do not significantly impair the effects of the technology disclosed herein. The type of such metal particles is not particularly limited, and one type can be used alone or two or more types can be used in appropriate combinations from among those conventionally known, for example, depending on the application of the electrode layer. Examples of such metal particles other than Ni particles include, for example, elemental base metals such as aluminum (Al), copper (Cu), and tungsten (W), elemental noble metals such as gold (Au), silver (Ag), platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), ruthenium (Ru), and osmium (Os), and mixtures and alloys thereof. When metal particles other than Ni particles are included, the content ratio is, for example, 2 wt% or less, and preferably 1 wt% or less, relative to the total Ni paste.

[0032] (B) Dielectric particles Dielectric particles are components that are placed between Ni particles during the firing of Ni paste and mitigate the thermal shrinkage of Ni particles. In applications where an internal electrode layer is formed in MLCCs, they can also function as a co-material that improves the sintering bond between the dielectric layer and the internal electrode layer. The dielectric constant of the dielectric particles is not particularly limited, but is typically 100 or more, for example, around 1000 to 20000. However, the dielectric particles may have a relative permittivity of less than 100, and may even be insulating materials.

[0033] The type of dielectric particles is not particularly limited, and can be used from conventionally known inorganic materials, for example, one type alone or two or more types in appropriate combinations depending on the application. Examples of dielectric particles include barium titanate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, zirconium titanate, zinc titanate, barium magnesium niobate, calcium zirconate, strontium zirconate, etc. ３ Examples include metal oxides having a perovskite structure represented by , and other metal oxides such as titanium dioxide, titanium pentoxide, hafnium oxide, zirconium oxide, aluminum oxide, forsterite, niobium oxide, and barium neodymate titanate. For example, in applications for forming the internal electrode layer of MLCCs, strontium titanate and calcium zirconate can be suitably used. Although not limited thereto, in some preferred embodiments, it is preferable to include barium titanate particles as dielectric particles. In the Ni paste according to this disclosure, by including barium titanate particles as dielectric particles, a Ni paste in which the separation of dielectric particles is suitably suppressed can be obtained. When barium titanate particles are included as dielectric particles, the content of barium titanate particles to the total dielectric particles may be, for example, 80 wt% or more, preferably 85 wt% or more, more preferably 90 wt% or more, more preferably 95 wt% or more, more preferably 98 wt% or more, and even more preferably 99 wt% or more.

[0034] In the Ni paste disclosed herein, the ratio of the weight (wt%) of dielectric particles to the weight (wt%) of Ni particles contained in the Ni paste (dielectric particles / Ni particles) is 0.05 or more (preferably 0.06 or more, 0.07 or more, 0.08 or more, 0.09 or more, 0.1 or more, 0.12 or more, or 0.15 or more). This provides suitable heat resistance. On the other hand, although not limited thereto, the ratio of the weight (wt%) of dielectric particles to the weight (wt%) of Ni particles contained in the Ni paste (dielectric particles / Ni particles) is preferably 0.4 or less, preferably 0.35 or less, more preferably 0.3 or less, even more preferably 0.25 or less, and particularly preferably 0.2 or less, from the viewpoint of forming a thin-layer electrode.

[0035] The content of dielectric particles relative to the total Ni paste (100 wt%) is preferably 2.0 wt% or more, preferably 2.5 wt% or more, preferably 3.0 wt% or more, preferably 3.5 wt% or more, preferably 5.0 wt% or more, more preferably 7.5 wt% or more, and even more preferably 10 wt% or more. This allows for suitable mitigation of thermal shrinkage of Ni particles during firing of the Ni paste. On the other hand, although not limited thereto, from the viewpoint of electrical conductivity, the content of dielectric particles relative to the total Ni paste (100 wt%) may be, for example, 20 wt% or less, preferably 17.5 wt% or less, preferably 15 wt% or less, and more preferably 12.5 wt% or less.

[0036] The manufacturing method of dielectric particles and the properties of the particles constituting them, such as particle size and shape, are not particularly limited. The particle size can be appropriately selected depending on the application of the Ni paste and the dimensions of the electrode layer. The particle size should be selected to fit within the minimum dimensions of the target electrode layer (e.g., internal electrode layer), such as thickness and / or width, taking into account the firing shrinkage rate. While not particularly limited, the average particle diameter D of the dielectric particles is also important. ２ The particle size may be approximately several nm to several μm, for example, 1 nm to 1 μm. For example, in applications where the internal electrode layer of an MLCC is formed, the average particle size D of the dielectric particles is ２However, it may be generally 5 nm or more, typically 10 nm or more, for example 20 nm or more, or 50 nm or more, and generally 0.5 μm or less, typically 0.3 μm or less, for example 0.2 μm or less, or 0.1 μm or less.

[0037] While not particularly limited, from the viewpoint of forming an electrode layer with excellent electrical conductivity, the average particle size D of the dielectric particles is ２ However, the average particle diameter D of Ni particles １ It is better if it is smaller than D. １ and D ２ D １ >D ２ It would be good if that were the case. D １ and D ２ is, (D １ / D ２ It is preferable that ) ≥ 2, and (D １ / D ２ It is more preferable that ) ≥ 3, for example (D １ / D ２ ) ≥ 4 may also be satisfied. When the average particle size differs significantly in this way, the application of the technology disclosed herein is particularly effective. Also, D １ and D ２ is 50 ≥ (D １ / D ２ ) may also be satisfied, and 20 ≥ (D １ / D ２ ) may also satisfy, for example, 10 ≥ (D １ / D ２ ) may also be satisfied.

[0038] (C) Binder Resin The binder resin is a component that adjusts the viscosity (fluidity) of the Ni paste and imparts tackiness to the coating film, causing inorganic particles to adhere to each other and to the substrate. The binder resin can be dissolved in the solvent (D) described later and function as a vehicle. The binder resin is typically a component that disappears by firing. In other words, the binder resin is a compound that burns away when the coating film is fired. The binder resin may have a decomposition temperature of, for example, 500°C or less.

[0039] The type of binder resin is not particularly limited, and from among conventionally known organic compounds used in this type of application, one type can be used alone or two or more types can be used in appropriate combinations, for example, depending on the application. The binder resin is typically a thermoplastic resin. However, it may also be a thermosetting resin. Examples of binder resins include organic polymer compounds such as cellulose resins, polyvinyl acetal resins, polyvinyl alcohol resins, acrylic resins, urethane resins, epoxy resins, phenolic resins, rosin resins, polyester resins, and ethylene resins. Among these, it is preferable to include a (C1) cellulose resin as the binder resin from the viewpoint of improving the burn-through properties during firing and the surface smoothness of the electrode layer. Furthermore, it is preferable to include a (C2) polyvinyl acetal resin as the binder resin from the viewpoint of improving the adhesion between the coating film and the substrate and the integrity of the coating film, and for example, it is preferable to use a combination of a (C1) cellulose resin and a (C2) polyvinyl acetal resin.

[0040] (C1) Cellulose resins encompass linear polymers (cellulose) containing β-glucose as a repeating unit, and their derivatives in general. Typically, they may be compounds in which some or all of the hydroxyl groups in the β-glucose structure, which is the repeating unit, are replaced with alkoxy groups, and their derivatives (modified products, etc.). The alkyl group or aryl group (R) in the alkoxy group (RO-) may be partially or entirely replaced with an ester group such as a carboxyl group, a nitro group, a halogen, or other organic group. Examples of cellulose resins include methylcellulose, ethylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose, carboxyethylcellulose, carboxyethylmethylcellulose, cellulose acetate phthalate, and nitrocellulose. Among these, methylcellulose and ethylcellulose are preferred. By including a cellulose resin, workability during gravure printing is improved, and a coating film with excellent surface smoothness can be stably formed.

[0041] The properties of the cellulose resin are not particularly limited. The weight-average molecular weight (Mw) of the cellulose resin may be approximately 20,000 or more, for example, 30,000 or more, 40,000 or more, or 50,000 or more. Alternatively, the weight-average molecular weight (Mw) of the cellulose resin may be approximately 180,000 or less, for example, 160,000 or less, 140,000 or less, 120,000 or less, or 100,000 or less. Note that "weight-average molecular weight (Mw)" is the average molecular weight based on the number of particles, and can be measured, for example, by gel chromatography (GPC) and calculated using a standard polystyrene calibration curve.

[0042] (C2) Polyvinyl acetal resins are resins obtained by reacting polyvinyl alcohol resins with aldehydes to acetalize them. Polyvinyl acetal resins encompass polymers and their derivatives (modified products, etc.) in general, which have structural units in which continuous vinyl alcohol structural units are acetalized by an aldehyde compound, and which may have one or more of the unreacted vinyl alcohol structural units and vinyl acetate structural units which are the unsaponified portion of the polyvinyl alcohol resin. The proportion of acetalized structural units (degree of acetalization) in polyvinyl acetal resins may be, for example, 50 mol% or more. Polyvinyl acetal resins have superior adhesion and flexibility compared to, for example, cellulose resins.

[0043] Examples of polyvinyl acetal resins include polyvinyl butyral resin, which has a structure in which polyvinyl alcohol is acetalized with butanol. Including polyvinyl butyral resin can improve the shape characteristics of the coating film. The polyvinyl acetal resin may be a copolymer (including graft copolymerization) in which the polyvinyl acetal resin is the main monomer (a component that accounts for 50% or more of the total monomer; the same applies hereinafter) and the main monomer contains copolymerizable sub-monomers. Examples of sub-monomers include ethylene, esters, (meth)acrylates, vinyl acetate, etc.

[0044] The properties of the polyvinyl acetal resin are not particularly limited. The weight-average molecular weight (Mw) of the polyvinyl acetal resin may be approximately 50,000 or more, for example, 75,000 or more, 85,000 or more, 100,000 or more, or 150,000 or more. Alternatively, the weight-average molecular weight (Mw) of the polyvinyl acetal resin may be approximately 1,000,000 or less, for example, 750,000 or less, or 500,000 or less, preferably 300,000 or less, 250,000 or less, for example, 200,000 or less. By setting the weight-average molecular weight to a predetermined value or less, the viscosity of the paste can be suitably suppressed. Therefore, good gravure printability can be achieved.

[0045] While not particularly limited, the binder resin may be composed primarily of (C2) polyvinyl acetal resin (the most abundant component; the same applies hereinafter). The (C2) polyvinyl acetal resin may account for approximately 50 wt% or more, for example, 60 to 80 wt%, when the total binder resin is considered to be 100 wt%. Furthermore, when the binder resin contains both (C1) cellulose resin and (C2) polyvinyl acetal resin, the (C2) polyvinyl acetal resin may account for approximately 10 to 90 wt%, typically 20 to 80 wt%, for example, 50 to 70 wt%, when (C1) + (C2) is considered to be 100 wt%.

[0046] While not particularly limited, the binder resin content is preferably 0.1 wt% or more, more preferably 0.5 wt% or more, and more preferably 1 wt% or more, relative to the total Ni paste, from the viewpoint of printability of the paste, adhesion to the substrate (e.g., green sheet, etc.), and shape retention of the coating film. On the other hand, from the viewpoint of printability of the paste and resin burning out during firing, the binder resin content is preferably 5 wt% or less, more preferably 4 wt% or less, and more preferably 3 wt% or less, relative to the total Ni paste.

[0047] (D) Solvent: The solvent is a liquid medium that disperses inorganic particles and imparts a viscosity (fluidity) to the Ni paste suitable for gravure printing. The solvent can also function as a vehicle for dissolving the (C) binder resin and / or the (E) dispersant described later. The solvent is typically a component that disappears by drying and firing. The solvent is a component that burns away when the Ni paste dries and / or when the coating film is fired.

[0048] The type of solvent is not particularly limited, and from among conventionally known organic solvents used in this type of application, one type can be used alone or two or more types can be used in appropriate combination, depending on the type of substrate to which the Ni paste is to be applied and the type of binder resin. In particular, from the viewpoint of suppressing the sheet attack phenomenon (the phenomenon in which the solvent erodes the green sheet), it is preferable to include a (D1) hydrocarbon solvent as the solvent. Furthermore, from the viewpoint of resin solubility, it is preferable to include a (D2) alcohol solvent as the solvent. Although not limited to these, for example, it is preferable to use a combination of a (D1) hydrocarbon solvent and a (D2) alcohol solvent as the solvent.

[0049] (D1) Hydrocarbon solvents encompass all solvents composed solely of carbon and hydrogen elements. Examples of hydrocarbon solvents include aromatic hydrocarbon solvents such as toluene and xylene; paraffinic solvents such as normal paraffins and isoparaffins; naphthenic solvents such as monocyclic naphthenes and bicyclic naphthenes; paraffin / naphthene mixed solvents; and aliphatic hydrocarbon solvents such as mineral spirits. Although not limited to these, from the viewpoint of suppressing the sheet attack phenomenon, it is preferable to include naphthenic solvents as hydrocarbon solvents, and the hydrocarbon solvent may be composed mainly of naphthenic solvents.

[0050] (D2) Alcohol-based solvents include all solvents having an -OH group. Examples of alcohol-based solvents include terpineol, texanol, dihydroterpineol, benzyl alcohol, 3-methoxy-3-methyl-1-butanol, phenoxyethanol, 1-phenoxy-2-propanol, isoborneol, and diethylene glycol. Although not limited to these, from the viewpoint of resin solubility, it is preferable to include dihydroterpineol as the alcohol-based solvent, and the alcohol-based solvent may be composed mainly of dihydroterpineol.

[0051] Furthermore, (D) the solvent may include solvents other than (D1) hydrocarbon solvents and (D2) alcohol solvents. Examples of such solvents include ester solvents having an ester bond (R-C(=O)-O-R') and ether solvents having an ether bond (R-O-R'). Examples of ester solvents include 3-methoxy-3-methyl-1-butanol acetate, 3-methoxybutyl acetate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol diacetate, cyclohexanol acetate, isobornyl acetate, carbitol acetate, ethyl diglycol acetate, butyl glycol acetate, butyl diglycol acetate, butyl cellosolve acetate, diethylene glycol monobutyl ether acetate (butyl carbitol acetate), terpineol acetate, and dihydroterpineol acetate. Examples of ether-based solvents include dipropylene glycol methyl ether, methyl cellosolve (ethylene glycol monomethyl ether), cellosolve (ethylene glycol monoethyl ether), and butyl carbitol (diethylene glycol monobutyl ether).

[0052] While not particularly limited, the solvent content may be approximately 10-70 wt%, typically 20-60 wt%, or for example, 30-50 wt%, when the total Ni paste is considered to be 100 wt%. By satisfying the above range, the Ni paste can be given appropriate fluidity, improving workability during gravure printing. Furthermore, it improves self-leveling properties, enabling the stable formation of a coating film with excellent surface smoothness even during high-speed printing.

[0053] While not particularly limited, the solvent may be composed mainly of (D2) alcohol-based solvent. The (D2) alcohol-based solvent may account for approximately 30 to 60 wt%, for example 40 to 50 wt%, when the total solvent is considered to be 100 wt%. Furthermore, when the solvent contains both (D1) hydrocarbon-based solvent and (D2) alcohol-based solvent, the (D1) hydrocarbon-based solvent may account for approximately 10 to 50 wt%, for example 15 to 45 wt%, when the total solvent is considered to be 100 wt%.

[0054] While not particularly limited, solvents other than (D1) hydrocarbon solvents may include high-boiling-point solvents with a boiling point of approximately 100°C or higher, for example, 200°C or higher, from the viewpoint of improving the storage stability of the Ni paste and the workability during gravure printing. Furthermore, from the viewpoint of rapidly drying the coating film and improving productivity, it is preferable to use a high-boiling-point solvent with a boiling point of approximately 100 to 300°C, for example, 200 to 250°C, preferably 230°C or lower, as the main component. The high-boiling-point solvent may account for approximately 50 wt% or more, for example, 90 wt% or more, when the total amount of solvents other than (D1) hydrocarbon solvents is considered to be 100 wt%, and substantially the entire solvent (95 wt% or more) may be composed of high-boiling-point solvents.

[0055] (E) Dispersant The dispersant is used to uniformly disperse the inorganic particles described above, namely (A) Ni particles and (B) dielectric particles, in the Ni paste, thereby suppressing the aggregation of these components.

[0056] The type of dispersant is not particularly limited, and one or more dispersants can be used from among various known dispersants as needed. Typically, dispersants with sufficient compatibility with the solvent can be appropriately selected and used. There are various ways to classify dispersants, but examples include anionic dispersants, cationic dispersants, nonionic dispersants, and amphoteric dispersants. Although not limited to these, it is preferable that the dispersant includes (E1) anionic dispersants and (E2) nonionic dispersants, and for example, it is preferable to use a combination of (E1) anionic dispersants and (E2) nonionic dispersants.

[0057] (E1) Anionic dispersants are, for example, dispersants having anionic functional groups. Anionic dispersants adhere to the surface of particles, for example, via anionic functional groups, causing steric hindrance. This suppresses aggregation of ceramic particles and, consequently, improves the long-term stability of the ink.

[0058] As an anionic dispersant, conventionally known anionic dispersants used for this type of application can be used without particular limitation. Examples of anionic dispersants include those containing one or more carboxyl groups (COO) in the molecule. － Dispersants having a group (carboxylic acid-based dispersants), one or more phosphonic acid groups (PO) in the molecule ３ － Group, P.O. ３ ２－ Dispersants having a sulfonic acid group (SO) (phosphate-based dispersants), one or more sulfonic acid groups (SO) in the molecule ３ － Base, SO ３ ２－ Examples of dispersants include those having a group (sulfonic acid-based dispersants). Among these, carboxylic acid-based dispersants are preferably used as anionic dispersants. Examples of carboxylic acid-based dispersants include monocarboxylic acid-based dispersants, dicarboxylic acid-based dispersants, polycarboxylic acid-based dispersants, and polycarboxylic acid partial alkyl ester-based dispersants.

[0059] The weight-average molecular weight (Mw) of the anionic dispersant may be approximately 500 or more, for example, 1000 or more, 3000 or more, 5000 or more, 8000 or more, or 10,000 or more. Alternatively, the weight-average molecular weight (Mw) of the anionic dispersant may be approximately 50,000 or less, 40,000 or less, 30,000 or less, 25,000 or less, 20,000 or less, or 15,000 or less. By setting the weight-average molecular weight (Mw) of the anionic dispersant to a predetermined value or higher, the effect of improving the uniform dispersion of Ni particles and dielectric particles can be better exhibited.

[0060] (E2) Nonionic dispersants are dispersants that do not have groups that ionize when dissolved in water. For this reason, they do not adhere as well to the surface of inorganic particles as anionic dispersants that have ionizing groups. On the other hand, nonionic dispersants can adsorb to particles or other dispersants, thereby improving the dispersion effect of other dispersants without adversely affecting their effect. This further improves the dispersibility of inorganic particles in Ni paste. Regarding nonionic dispersants, conventionally known nonionic dispersants can be used without any particular restrictions. Examples of such nonionic dispersants include ether-based dispersants, ester-based dispersants, ether-ester-based dispersants, and nitrogen-containing dispersants.

[0061] While not particularly limited, when the total Ni paste is considered to be 100 wt%, the dispersant content is generally 0.01 wt% or more, for example, 0.05 wt% or more, and preferably 0.1 wt% or more. This allows the dispersant to act sufficiently on the inorganic particles. Furthermore, from the viewpoint of forming an electrode layer with excellent electrical conductivity and density, the dispersant content is generally 5 wt% or less, for example, 3 wt% or less, preferably 2 wt% or less, and more preferably 1 wt% or less.

[0062] (F) Thickening inhibitor (F) The thickening inhibitor is for suppressing the increase in viscosity of the Ni paste over time. Although not limited to this, the Ni paste disclosed herein may contain a thickening inhibitor. With such a configuration, the thickening of the Ni paste after manufacturing can be effectively suppressed.

[0063] The type of thickening inhibitor is not particularly limited, and one or more known thickening inhibitors can be used as needed. However, it is preferable that the thickening inhibitor includes a secondary amine compound. The secondary amine compound has the general formula: NHR １ R ２ It is represented by ; and ammonia (NH ３ Two hydrogen atoms (H) of ) are attached to a hydrocarbon-containing functional group R １ and R ２ It is a compound with a substituted structure.

[0064] Examples of secondary amine compounds include dialkylamines such as dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, diundecylamine, and didodecylamine; butylpentylamine, butylhexylamine, butylheptylamine, butyloctylamine, butylnonylamine, butyldecylamine, butylundecylamine, butyldodecylamine, pentylhexylamine, pentylheptylamine, pentyloctylamine, pentylnonylamine, pentyldecylamine, pentylundecylamine, pentyldodecylamine, hexylheptylamine, hexyloctylamine, hexylnonylamine, hexyldecylamine, hexylundecylamine, hexyldodecylamine, heptyloctylamine, heptylnonylamine, heptyldecylamine, heptylun Examples include alkylamines such as decylamine, heptyldodecylamine, octylnonylamine, octyldecylamine, octylundecylamine, octyldodecylamine, nonyldecylamine, nonylundecylamine, nonyldodecylamine, decylundecylamine, decyldodecylamine, and undecyldodecylamine; dicycloalkylamines such as dicyclobutylamine, dicyclopentylamine, dicyclohexylamine, dicycloheptylamine, dicyclooctylamine, dicyclononylamine, dicyclodecylamine, dicyclopentylamine, and dicyclopentylamine; and alkylcycloalkylamines such as cyclohexylbutylamine, cyclohexylpentylamine, cyclohexylamine, heptylcyclohexylamine, octylcyclohexylamine, nonylcyclohexylamine, and cyclopentylcyclohexylamine. Furthermore, secondary amine compounds may be related compounds and derivatives of the above compounds. These secondary amine compounds may be present individually or in combination of two or more.

[0065] While not particularly limited, when the total Ni paste is considered to be 100 wt%, the content of the thickening inhibitor is generally 0.01 wt% or more, for example, 0.05 wt% or more, and preferably 0.1 wt% or more. This allows for a suitable thickening inhibitory effect on the Ni paste. On the other hand, from the viewpoint of forming an electrode layer with excellent electrical conductivity and density, the content of the thickening inhibitor is generally 5 wt% or less, for example, 3 wt% or less, preferably 2 wt% or less, and more preferably 1 wt% or less.

[0066] (G) Other Additives The Ni paste disclosed herein may contain various additives known to be used in general Ni pastes, to the extent that they do not significantly impair the effects of the technology of this disclosure. Examples of such additives include viscosity modifiers, defoamers, plasticizers, leveling agents, pH adjusters, stabilizers, antioxidants, preservatives, and colorants (pigments, dyes, etc.). These additives may be used individually or in combination of two or more as needed.

[0067] Additives can be included in appropriate proportions depending on the purpose of their addition. While not particularly limited, when the total Ni paste is considered to be 100 wt%, the additive content should generally be kept to 5 wt% or less, typically 3 wt% or less, for example, 1 wt% or less. This allows for the desirable realization of an electrode layer with excellent electrical conductivity and density.

[0068] <Properties of Ni Paste> The Ni paste disclosed herein is prepared in such a way that the floating (separation) of dielectric particles in the Ni paste is suppressed. Specifically, when 0.5 g of the diluted paste obtained by diluting the Ni paste disclosed herein to a solid content concentration of 20 wt% is subjected to centrifugal sedimentation under the following conditions: Temperature: 25°C; Rotation speed: 4000 rpm; Processing time: 6200 seconds, the weight W of the dielectric contained in the 0.5 g of the diluted paste is ａThe weight W of the dielectric contained in 0.3 g of the supernatant liquid of the diluted paste after centrifugal sedimentation treatment, as measured by inductively coupled plasma (ICP) emission spectrometry (ICP analysis), relative to (mg). ｂ The ratio of (mg) is 13% or less. The solvent used when preparing the diluted paste is the solvent contained in the Ni paste. If the Ni paste contains two or more solvents, the diluted paste is prepared using the solvent with the highest concentration among the solvents contained in the Ni paste, and the above measurement is performed. In this specification, "weight W of dielectric material contained in 0.5 g of diluted paste" refers to the dielectric material contained in 0.5 g of the diluted paste. ａ The value "(mg)" can be calculated from the weight ratio (wt%) of the dielectric contained in the Ni paste before dilution. Furthermore, "the weight W of the dielectric contained in 0.3 g of the supernatant liquid of the diluted paste" as used herein. ｂ The value (mg) can be calculated based on the content of metal elements constituting dielectric particles in the supernatant liquid of the diluted paste after centrifugal sedimentation, obtained by ICP analysis. Depending on the detection range of the instrument used for ICP analysis, the supernatant liquid may be further diluted with a solvent before ICP analysis.

[0069] Typically, gravure printing is faster than screen printing. Therefore, if the viscosity of the Ni paste is adjusted to the same level as that used for screen printing, the surface of the coating may become rough and uneven. This can lead to distortion of the laminated structure and cause defects such as short circuits. For this reason, Ni paste for gravure printing needs to be adjusted to a lower viscosity than that for screen printing. However, in Ni paste adjusted to a low viscosity for gravure printing, separation (lifting) of dielectric particles in the Ni paste may occur. When a coating is formed using Ni paste in which dielectric particles have separated, it is difficult to form a homogeneous coating, which may lead to a decrease in yield.

[0070] The Ni paste disclosed herein is, as described above, W ａ W relative to (mg) ｂThe ratio of (mg) is 13% or less (preferably 12% or less, more preferably 11% or less). Based on the results of experiments conducted by the present inventors, W ａ W relative to (mg) ｂ In Ni pastes where the ratio of (mg) is 13% or less, the separation of dielectric particles in the Ni paste is suitably suppressed, and it has been confirmed that the lower the ratio, the more suitably the separation of dielectric particles is suppressed. Therefore, with the Ni paste of this disclosure, it is possible to form a homogeneous coating film.

[0071] While not particularly limited, the lower the viscosity of the Ni paste, the more suitable it can be for gravure printing applications with high printing speeds. Therefore, in an environment of 25°C, the shear rate is 10,000 sec. －１ Viscosity V of Ni paste when measured ｍ From the viewpoint of increasing productivity by speeding up printing, a viscosity of 0.3 Pa·s or less is preferred, more preferably 0.25 Pa·s or less, and even more preferably 0.2 Pa·s or less. On the other hand, from the viewpoint of improving workability by suppressing printing sagging, etc., viscosity V ｍ However, it may be adjusted to, for example, 0.02 Pa·s or higher, or 0.05 Pa·s or higher. The viscosity of the Ni paste can be adjusted by, for example, the type and proportion of binder resin, the type and proportion of dispersant, the type and proportion of solvent, and the addition of other additives (e.g., viscosity modifiers, thickeners). Also, the viscosity of the Ni paste (V ｍ and V ｈ ) can be measured using a rotary rheometer.

[0072] While not particularly limited, in an environment of 25°C, a shear rate of 100 sec －１ Viscosity V of Ni paste when measured ｈ The viscosity may be adjusted to approximately 3.0 Pa·s or less, 2.5 Pa·s or less, 2.0 Pa·s or less, 1.5 Pa·s or less, or 1.0 Pa·s or less. ｈ For example, it may be adjusted to 0.1 Pa·s or higher, 0.2 Pa·s or higher, or 0.3 Pa·s or higher.

[0073] This is not limited to viscosity V ｍViscosity V ｈ The ratio (V ｈ / V ｍ The ratio is preferably 8 or less, more preferably 7.5 or less, even more preferably 7 or less, even more preferably 6.5 or less, and particularly preferably 6 or less. This improves the storage stability and handling properties of the Ni paste.

[0074] <Method for Manufacturing Ni Paste> The Ni paste disclosed herein can be prepared, for example, by preparing a vehicle by mixing a binder and a solvent, and then mixing and kneading Ni particles and dielectric particles into the vehicle. As an example of a method for manufacturing Ni paste, a dielectric particle slurry is prepared by dispersing dielectric particles in a solvent, and then an inorganic particle slurry is prepared by dispersing Ni particles in the dielectric particle slurry. Then, the inorganic particle slurry and the vehicle are mixed and a dispersion treatment is performed. This allows for better dispersion of Ni particles and dielectric particles in the solvent.

[0075] Here, W ａ W ｂ In order to control the ratio of to be below a predetermined value, if a conventional stirring and mixing device is used when performing dispersion treatment on the inorganic particle slurry and vehicle, the dispersion treatment intensity tends to become too high. When the dispersion treatment intensity is too high, the W of the obtained Ni paste ａ W ｂThe ratio of [specific component] may increase. The reason for this is not clear, but one possible cause is that if the dispersion treatment intensity becomes too high, the dispersant adhering (adsorbing) to the particle surface falls off, thereby reducing the dispersibility of the dielectric particles. Therefore, while stirring conditions cannot be generalized as they depend on the materials used and their properties, when using a known stirring and mixing device, it is generally preferable to prepare the paste under stirring conditions that reduce the dispersion treatment intensity. For example, if the dispersion treatment intensity in a conventional dispersion treatment performed on an inorganic particle slurry and a vehicle is set to 1, then it can be, for example, 0.5 times or less, may be 0.3 times or less, and more preferably 0.2 times or less. The lower limit of the dispersion treatment intensity is not particularly limited, but from the viewpoint of sufficiently dispersing Ni particles, it can be, for example, 0.02 times or more, and preferably 0.05 times or more.

[0076] Furthermore, when performing dispersion treatment on the inorganic particle slurry and vehicle, it is preferable to use a medium-less stirring or dispersion device for the stirring and dispersion treatment. A medium-less stirring or dispersion device refers to a stirring or dispersion device that does not have a hard medium (for example, a grinding member, a movable member, or a media) to exert a stirring or dispersion action such as impact on the fluid to be stirred or dispersed. The driving force of this medium-less stirring or dispersion device is, for example, a high-speed fluid such as compressed air, steam, or heated airflow, ultrasound, cavitation bubbles, etc., and the stirring or dispersion action is produced by the impact or impulse caused by this driving force, the mutual collision of particles, mutual friction, etc. Examples include planetary mixers, planetary mills, air-jet mills, jet mills, ultrasonic jet mills, and cross-jet mills. With this medium-less stirring and dispersion device, dispersion treatment can be performed under conditions with a milder dispersion treatment intensity compared to dispersion devices equipped with a hard medium.

[0077] Furthermore, various conventionally known stirring and dispersion devices can be used when preparing the vehicle, dielectric particle slurry, and inorganic particle slurry. For example, the above-mentioned medium-less stirring or dispersion device may be used, or a medium-type stirring or dispersion device may be used. As medium-type stirring and dispersion devices, for example, ball mills, bead mills, colloid mills, hammer mills, mortars, disc grinders, roller mills, etc., can be used as appropriate.

[0078] <Applications of Ni Paste> The Ni paste according to this embodiment has been described above. The Ni paste disclosed herein can be used, for example, to form internal electrodes of electronic components. In particular, it can be preferably used in applications where homogeneity of the electrode layer is required.

[0079] <Multilayer Ceramic Capacitor> The following describes the configuration of a multilayer ceramic capacitor (MLCC) as an example of an electronic component manufactured using the Ni paste disclosed herein. Figure 1 is a schematic cross-sectional view showing the configuration of an MLCC 1. An MLCC 1 is a chip-type capacitor composed of a number of dielectric layers 20 and internal electrode layers 30 stacked alternately and integrally. A pair of external electrodes 40 are provided on the side surface of the stacked chip 10 consisting of dielectric layers 20 and internal electrode layers 30. As an example, the internal electrode layers 30 are alternately connected to different external electrodes 40 in the stacking order. In this way, a capacitor structure consisting of a dielectric layer 20 and a pair of internal electrode layers 30 sandwiching it is connected in parallel, and a small, high-capacitance MLCC 1 is constructed. The dielectric layer 20 of the MLCC 1 is made of, for example, a dielectric material. The internal electrode layer 30 is made of a fired body of the Ni paste disclosed herein.

[0080] Furthermore, as another aspect of the technology disclosed herein, a method for manufacturing electronic components is provided. Such a manufacturing method includes applying the Ni paste disclosed herein onto a substrate and firing it. Below, an example of a method for manufacturing electronic components using the Ni paste of this disclosure will be described using MLCC1 as an example. Figure 2 is a schematic cross-sectional view showing the structure of an unfired laminate 10a (unfired laminated chip 10).

[0081] The manufacturing method of MLCC1 according to this embodiment includes a substrate preparation step, a paste application step, a laminated body manufacturing step, and a firing step. However, the manufacturing method is not limited to the following method.

[0082] (Substrate preparation process) In the substrate preparation process, a substrate to which Ni paste will be applied is prepared. Here, a dielectric green sheet is prepared as the substrate. For example, a paste for forming a dielectric layer is prepared by mixing ceramic powder as a dielectric material, a binder resin, and a solvent. Next, an unfired dielectric green sheet 20a is prepared by applying the prepared paste in a thin layer onto a carrier sheet using the doctor blade method or the like.

[0083] (Paste application process) In the paste application process, the Ni paste disclosed herein is applied to the substrate. Here, the prepared Ni paste is applied to the dielectric green sheet 20a in a predetermined pattern by gravure printing to a desired thickness (for example, a few μm or less), and then dried. This forms a coating film 30a. With the Ni paste disclosed herein, separation of dielectric particles is suitably suppressed, so a homogeneous coating film 30a can be stably formed.

[0084] (Laminated Crimped Body Manufacturing Process) In the laminated crimped body manufacturing process, multiple dielectric green sheets 20a with the prepared coating 30a are laminated (for example, several hundred to several thousand sheets) and crimped together. This produces a laminated crimped body. The laminated crimped body is cut into chip shapes as needed. Because the coating 30a has a smooth surface, distortion of the laminated structure is less likely to occur even when laminated and crimped. In addition, because the coating 30a has good adhesion to the dielectric green sheets 20a, problems such as cracking or peeling of the coating 30a are less likely to occur even when laminated, crimped, or cut. This makes it possible to stably obtain an unfired laminate 10a.

[0085] (Firing Process) In the firing process, the unfired laminate 10a is fired under appropriate heating conditions. As a result, the dielectric green sheet 20a is fired to become the dielectric layer 20. The coating film 30a is also fired to become the internal electrode layer 30. As described above, since a homogeneous coating film 30a is obtained by the Ni paste according to this embodiment, the internal electrode layer 30 can be formed as electrically continuous and homogeneous. The dielectric layer 20 and the internal electrode layer 30 are sintered together to obtain the laminated chip 10.

[0086] The firing temperature (maximum firing temperature) in the firing process is not particularly limited, but it is preferably a temperature at which the organic components in the Ni paste, such as (C) binder resin, (D) solvent, and (E) dispersant, can be eliminated. Such a firing temperature may be, for example, around 1000 to 1300°C.

[0087] Subsequently, the external electrode 40 is formed by applying an external electrode material to the side surface of the laminated chip 10 and baking it. In this way, a high-quality MLCC 1 can be manufactured.

[0088] The applications of the Ni paste disclosed herein are not limited to the MLCC described above. Other examples of electronic components in which the Ni paste disclosed herein may be used include, for example, chip inductors, high-frequency filters, High Temperature Co-fired Ceramics (HTCC) substrates, Low Temperature Co-fired Ceramics (LTCC) substrates, and the like.

[0089] The following describes some embodiments relating to the technology disclosed herein, but is not intended to be limited to those embodiments shown herein.

[0090] <Preparation of Ni Paste> Here, Ni pastes for each example to be used in each evaluation were prepared. In this test, the dispersion treatment intensity was adjusted to four different intensities (dispersion treatment intensities A to D) by changing the equipment, rotation speed, and peripheral speed during the preparation of the Ni paste. The dispersion treatment intensities are in the order of A > B > C > D, in other words, dispersion treatment intensity A is the strongest and dispersion treatment intensity D is the weakest. It should be noted that stirring under general conditions using conventionally used stirring devices generally results in an intensity close to dispersion treatment intensity A.

[0091] (Example 1) Here, Ni paste of formulation I shown in Table 1 was prepared using the following procedure. In Table 1, the proportion of Ni particles and dielectric particles in the Ni paste is shown as "Solid content concentration (wt%)". The weight ratio of dielectric particles to the weight of Ni particles (dielectric particles / Ni particles) is shown as "Weight ratio of dielectric particles to Ni particles".

[0092] Formula I used Ni particles with an average particle size of 0.2 μm. In addition, barium titanate particles with an average particle size of 0.1 μm were used as dielectric particles. As the binder resin, a mixture of ethyl cellulose (weight-average molecular weight (Mw): 77,000) and polyvinyl butyral (weight-average molecular weight (Mw): 85,000) was used. As solvents, a hydrocarbon solvent (naphthenic solvent) and an alcohol solvent (dihydroterpineol) were used. As dispersants, a carboxylic acid-based dispersant (polycarboxylic acid-based dispersant, weight-average molecular weight (Mw): 13,000) and a nonionic dispersant were used. Furthermore, a secondary amine compound was used as a thickening inhibitor.

[0093] First, a dielectric particle slurry was prepared by mixing barium titanate particles, dihydroterpineol, and a carboxylic acid-based dispersant, and then dispersing them using a medium-type mill. The weight ratio (wt%) of each material in the dielectric particle slurry was set to barium titanate particles:dihydroterpineol:carboxylic acid-based dispersant = 50:48:2.

[0094] On the other hand, a vehicle was prepared separately by mixing ethylcellulose, polyvinyl butyral, and dihydroterpineol. The weight ratio (wt%) of each material contained in the vehicle was ethylcellulose:polyvinyl butyral:dihydroterpineol = 8:12:80.

[0095] Next, when the total adjusted Ni paste is considered to be 100 wt%, the Ni particles, the dielectric particle slurry, and the naphthenic solvent were added to a stirrer so that they constituted 50 wt%, 25 wt%, and 5 wt%, respectively. The mixture was then stirred, and subsequently dispersed using a bead mill. In this way, an inorganic particle slurry was obtained.

[0096] Next, the vehicle prepared above, a naphthenic solvent, dihydroterpineol, a nonionic dispersant, and a secondary amine compound were added to the inorganic particle slurry. At this time, when the total Ni paste after preparation is considered to be 100 wt%, the inorganic particle slurry, vehicle, naphthenic solvent, dihydroterpineol, nonionic dispersant, and secondary amine compound were blended in amounts of 80 wt%, 13 wt%, 3 wt%, 3.2 wt%, 0.2 wt%, and 0.6 wt%, respectively. Then, the dispersion treatment was carried out 20 times in a bead mill using φ0.2 mm beads at a stirring speed of 12 m / s (dispersion treatment strength A). This prepared the Ni paste according to Example 1.

[0097] (Example 2) In Example 2, when preparing the Ni paste, the Ni paste was prepared by performing a dispersion treatment 20 times in a bead mill using φ0.2 mm beads at a stirring speed of 8 m / s (dispersion treatment strength B). All other conditions and the composition of the Ni paste (composition I) were the same as in Example 1. This yielded the Ni paste of Example 2.

[0098] (Example 3) In Example 3, when preparing the Ni paste, a dispersion treatment was performed for 240 seconds using a planetary mill at a rotational speed of 781 rpm and an orbital speed of 1420 rpm (dispersion treatment intensity C) to prepare the Ni paste. All other conditions and the composition of the Ni paste (composition I) were the same as in Example 1. This yielded the Ni paste of Example 3.

[0099] (Example 4) In Example 4, when preparing the Ni paste, a dispersion treatment was performed for 240 seconds using a planetary mill at a rotational speed of 385 rpm and an orbital speed of 700 rpm (dispersion treatment intensity D) to prepare the Ni paste. All other conditions and the composition of the Ni paste (composition I) were the same as in Example 1. This yielded the Ni paste of Example 4.

[0100] (Example 5) In Example 5, instead of formulation I, Ni paste of formulation II shown in Table 1 was prepared. In formulation II, Ni particles with an average particle size of 0.18 μm were used. In addition, barium titanate particles with an average particle size of 0.05 μm were used as dielectric particles in formulation II. The other materials were the same as in formulation I.

[0101] First, a dielectric particle slurry was prepared by mixing barium titanate particles, dihydroterpineol, and a carboxylic acid-based dispersant. In Example 5, the weight ratio (wt%) of each material contained in the dielectric particle slurry was the same as in Example 1 (Formulation I). The dispersion conditions for the dielectric particle slurry were also the same as in Example 1.

[0102] On the other hand, in Example 5, a vehicle was prepared separately using the same formulation and method as in Example 1 (Formulation I).

[0103] Next, when the total adjusted Ni paste is considered to be 100 wt%, the Ni particles, the dielectric particle slurry, dihydroterpineol, and naphthenic solvent were added to a stirrer in amounts of 50 wt%, 10 wt%, 12 wt%, and 5 wt%, respectively. The mixture was then stirred, and subsequently dispersed using a bead mill. In this way, an inorganic particle slurry was obtained.

[0104] Next, the vehicle prepared above, a naphthenic solvent, dihydroterpineol, a carboxylic acid-based dispersant, a nonionic dispersant, and a secondary amine compound were added to the inorganic particle slurry. At this time, when the total volume of the prepared Ni paste is considered to be 100 wt%, the inorganic particle slurry, vehicle, naphthenic solvent, dihydroterpineol, carboxylic acid-based dispersant, nonionic dispersant, and secondary amine compound were blended in amounts of 77 wt%, 14 wt%, 5 wt%, 3.1 wt%, 0.2 wt%, 0.2 wt%, and 0.5 wt%, respectively. Then, the Ni paste was prepared by performing a dispersion treatment (dispersion treatment intensity A) in the same manner as in Example 1 for 20 passes using a bead mill with φ0.2 mm beads.

[0105] (Example 6) In Example 6, instead of formulation I, Ni paste of formulation II shown in Table 1 was prepared. In Example 6, the preparation conditions for the dielectric particle slurry, vehicle, and inorganic particle slurry were the same as in Example 5. On the other hand, in Example 6, when dispersing the inorganic particle slurry, the vehicle prepared above, a naphthenic solvent, dihydroterpineol, a carboxylic acid-based dispersant, a nonionic dispersant, and an amine-based additive, the Ni paste was prepared by performing 20 passes of the same dispersion treatment (dispersion treatment intensity B) as in Example 2.

[0106] (Example 7) In Example 7, instead of formulation I, Ni paste of formulation II shown in Table 1 was prepared. In Example 7, the preparation conditions for the dielectric particle slurry, vehicle, and inorganic particle slurry were the same as in Example 5. On the other hand, in Example 7, when dispersing the inorganic particle slurry, the vehicle prepared above, a naphthenic solvent, dihydroterpineol, a carboxylic acid-based dispersant, a nonionic dispersant, and an amine-based additive, the Ni paste was prepared by performing the same dispersion treatment (dispersion treatment intensity C) as in Example 3 for 240 seconds.

[0107] (Example 8) In Example 8, instead of formulation I, a Ni paste of formulation II shown in Table 1 was prepared. In Example 8, the preparation conditions for the dielectric particle slurry, the vehicle, and the inorganic particle slurry were the same as in Example 5. On the other hand, in Example 8, when adding the inorganic particle slurry, the vehicle prepared above, a naphthenic solvent, dihydroterpineol, a carboxylic acid-based dispersant, a nonionic dispersant, and an amine-based additive and performing dispersion treatment, the same dispersion treatment as in Example 4 (dispersion treatment intensity D) was performed for 240 seconds to prepare a Ni paste.

[0108]

[0109] <Measurement of Paste Viscosity> Using a rotational vibration rheometer MARS iQ Air manufactured by HAAKE, the viscosity of the Ni pastes of Examples 1 to 8 was measured. The measurement conditions are as follows. Shear rate 10000 sec －１ viscosity V at ｍ (Pa·S), and shear rate 100 sec －１ viscosity V at ｈ (Pa·S) are each shown in Table 2. Further, the viscosity V ｍ ratio of viscosity V to ｈ (V ｈ / V ｍ ) is shown in the column of "Viscosity ratio (V ｈ / V ｍ )" in Table 2. Measurement mode: shear rate dependency measurement Sensor: cone plate (φ35 mm, angle 0.5°) Measurement temperature: 25°C Gap: 0.027 mm Shear rate: 10000 to 0.01 s －１ Measurement time: 3 minutes

[0110] [Evaluation of Dispersibility of Dielectric Particles] Here, the dispersibility of dielectric particles (barium titanate particles) in the Ni pastes of each example was evaluated. First, diluted pastes were prepared by diluting the Ni paste of each example to a solid content concentration of 20 wt%. Dihydroterpineol was used as the solvent for preparing the diluted pastes. When diluting, to prevent so-called solvent shock, the solvent was added dropwise with a burette while stirring the Ni paste. Specifically, 10 g of Ni paste was measured into a 100 mL beaker, and while stirring the Ni paste in the beaker with a small stirrer (using 6 blades, rotation speed approximately 200 rpm), the solvent was added in increments of approximately 2 mL at approximately 5-second intervals. The amount of solvent added was 21.25 g for 10 g of Ni paste in Examples 1 to 4, and 18.6 g for 10 g of Ni paste in Examples 5 to 8.

[0111] The diluted pastes prepared above were subjected to centrifugal sedimentation using a dispersion stability analyzer (LUM GmbH, LUMIFuge). First, 0.5 g of the diluted paste was weighed and slowly filled into a disposable, rectangular polyamide sample cell for the analyzer from the bottom, and then capped. This procedure was performed for each example of diluted paste. Next, the sample cell containing the diluted paste was set horizontally on the rotor of the dispersion stability analyzer (so that the longitudinal direction of the cell coincided with the centrifugation direction), and centrifugal sedimentation was performed under the following conditions: Temperature: 25°C, Rotation speed: 4000 rpm, Processing time: 6200 seconds

[0112] On the other hand, the barium titanate concentration (wt%) in the diluted paste was calculated. Furthermore, based on the obtained concentration, the amount (mg) of barium titanate (dielectric particles) contained in 0.5 g of the diluted paste was calculated. The results are shown in the "Dielectric Particle Concentration" and "Weight (Wt%) of Dielectric Particles Contained in 0.5 g of Diluted Paste" columns of Table 2. ａ These are shown in the respective sections of ').

[0113] After centrifugal sedimentation, 0.3 g of the supernatant of the diluted paste in the sample cell was taken out. A sample for ICP analysis was prepared by adding 2 g of dihydroterpineol to 0.3 g of the taken-out supernatant of the diluted paste for dilution. For the ICP analysis sample, an ICP measuring apparatus (5800 ICP-OES, manufactured by Agilent) was used to measure the mass concentrations of Ba and Ti in the ICP analysis sample of each example, and conversion was performed to obtain the barium titanate concentration (ppm) in the ICP analysis sample. The calculated barium titanate concentration is shown in "Barium titanate concentration in ICP analysis sample" in Table 2. Further, from these results, the amount (mg) of barium titanate (dielectric particles) in 0.3 g of the supernatant (that is, before dilution as the ICP analysis sample) was calculated. The results are shown in "Weight of dielectric particles contained in 0.3 g of supernatant (W ｂ )" in Table 2.

[0114] Using W ａ (mg) of dielectric particles contained in 0.5 g of the diluted paste calculated above and the weight W ｂ (mg) of dielectric particles in 0.3 g of the supernatant, the ratio of the weight W ａ (mg) of dielectric particles contained in 0.3 g of the supernatant of the diluted paste after the centrifugal sedimentation treatment measured by ICP to the weight W ｂ (mg) of dielectric particles contained in 0.5 g of the diluted paste (W ｂ / W ａ ×100) was calculated. The results are described in "Ratio of W ａ to W ｂ " in Table 2.

[0115] <Observation of coating film by SEM> (Examples 1 to 8) First, the Ni paste of each example was applied onto a PET substrate to a thickness of about 250 μm using an applicator, and dried at 110° C. for about 15 minutes to form a coating film (about 50 μm). Then, this coating film was observed from the surface on the PET substrate side using a scanning electron microscope (SEM) to obtain SEM observation images. The acceleration voltage during SEM observation was set to 20 kV, and the observation magnification was set to 10,000 times. The SEM observation images of the Ni paste coating films of each obtained example are shown in Figure 3.

[0116] <Evaluation of the Dispersion Index of Ni Particles> (Examples 1 to 8) Here, the dispersibility of Ni particles in the coating films obtained in Examples 1 to 8 above was evaluated. First, based on the SEM observation images obtained above, the dispersion index of the conductive powder was calculated according to the dispersibility evaluation method disclosed in Japanese Patent Application Publication No. 2015-7542. That is, first, the SEM observation images were binarized at a predetermined threshold to generate an evaluation image. Figure 4 is a conceptual diagram illustrating the method for calculating the dispersion index. Next, the evaluation image was divided into equal-sized sections until a predetermined number of divisions were reached, and the evaluation image variation coefficient CVb and the complete separation variation coefficient CVa were calculated for each section size. The evaluation image variation coefficient CVb was calculated based on the area value x and standard deviation σ of the object (for example, the white portion after binarization representing the conductive powder). The complete separation variation coefficient CVa was calculated based on the area value of the object assuming that the object and non-objects other than the object were completely separated. Furthermore, the evaluation images were divided until the evaluation image variation coefficient CVb was the same as the variation coefficient CVa under complete separation. In addition, for each section size, the variation coefficient CVc under complete mixing was calculated based on the area value of the object assuming that the object and non-objects other than the object were completely mixed.

[0117] Next, the plot size and the evaluation image variation coefficient CVb were plotted on a two-dimensional coordinate system, and the values ​​of the evaluation image variation coefficient CVb between adjacent plot sizes were connected by straight lines to graph the "first relationship b" in Figure 4. Similarly, the plot size and the variation coefficient CVa during complete separation were plotted on a two-dimensional coordinate system, and the values ​​of the variation coefficient CVa during complete separation between adjacent plot sizes were connected by straight lines to graph the "second relationship a" in Figure 4. Furthermore, the plot size and the variation coefficient CVc during complete mixing were plotted on a two-dimensional coordinate system, and the values ​​of the variation coefficient CVc during complete mixing between adjacent plot sizes were connected by straight lines to graph the "third relationship c" in Figure 4.

[0118] Next, the integral values ​​were calculated for the first relation b, the second relation a, and the third relation c, within the range from the minimum section size (i.e., the maximum number of divisions) to the maximum section size (i.e., the minimum number of divisions). That is, as shown in Figure 4, the area enclosed by the first relation b and the horizontal axis was defined as B, the area enclosed by the second relation a and the horizontal axis was defined as A, and the area enclosed by the third relation c and the horizontal axis was defined as C. Then, the dispersion index was calculated based on the following formula: Dispersion index α [%] = (1 - (B - C) / (A - C)) × 100; The results are shown in the "Dispersion Index α" column of Table 2. Note that the closer this dispersion index α is to 100%, the better the dispersibility of Ni particles in the coating film (i.e., the Ni particles are highly dispersed, close to a completely mixed state).

[0119]

[0120] As shown in Table 2, even if the raw materials used are the same, the Ni paste's W content can be changed by altering the preparation method. ａ W ｂ Differences in the ratio were observed. Furthermore, as shown in Figure 3, the Ni pastes according to Examples 3 and 4 produced a more homogeneous coating film compared to the Ni pastes according to Examples 1 and 2. Similarly, the coating films produced by Examples 7 and 8 were also more homogeneous compared to the Ni pastes according to Examples 5 and 6. From this, it can be concluded that the W of the Ni paste... ａ W ｂ It was found that by setting the ratio to 13% or less, the separation of dielectric particles in the Ni paste was suppressed, and a homogeneous coating film could be obtained. Furthermore, as shown in Table 2, there was almost no change in the dispersion index α due to the change in the preparation method. In other words, it appears that the Ni pastes of Examples 3-4 and Examples 7-8 were able to suppress the separation of dielectric particles while maintaining the dispersibility of Ni particles.

[0121] Preferred embodiments of the technology disclosed herein have been described above. However, the embodiments described above are merely illustrative, and the present invention can be implemented in various other forms. This disclosure can be implemented based on the content disclosed herein and common technical knowledge in the art. The technologies described in the claims include various modifications and changes to the embodiments illustrated above. For example, some of the embodiments described above can be combined or replaced with other variations. Furthermore, technical features that are not described as essential can be deleted as appropriate.

[0122] As described above, specific embodiments of the technology disclosed herein include those described in the following sections.

[0123] [Item 1] A Ni paste for gravure printing comprising Ni particles, dielectric particles, a binder resin, a solvent, and a dispersant, wherein the Ni particles are present in an amount of 35 wt% or more relative to the total Ni paste, and the ratio of the weight (wt%) of the dielectric particles to the weight (wt%) of the Ni particles (dielectric particles / Ni particles) is 0.05 or more, and when 0.5 g of the diluted paste obtained by diluting the Ni paste to a solid content concentration of 20 wt% is subjected to centrifugal sedimentation treatment by rotating under the following conditions: Temperature: 25°C; Rotation speed: 4000 rpm; Processing time: 6200 seconds, the weight W of the dielectric particles contained in 0.5 g of the diluted paste is ａ The weight W of dielectric particles contained in 0.3 g of the supernatant liquid of the diluted paste after the centrifugal sedimentation treatment in inductively coupled plasma atomic emission spectrometry (mg) ｂ Ni paste with a ratio of (mg) of 13% or less.

[0124] [Item 2] The Ni paste according to Item 1, wherein the ratio of the weight (wt%) of dielectric particles to the weight (wt%) of Ni particles (dielectric particles / Ni particles) is 0.3 or less.

[0125] [Item 3] Under conditions of 25°C, shear rate of 10,000 sec －１ The viscosity V of the above Ni paste when measured ｍ Ni paste as described in item 1 or 2, wherein the pressure is 0.3 Pa·S or less.

[0126] [Item 4] The above viscosity V ｍ For a shear rate of 100 sec in an environment of 25°C －１ The viscosity V of the above Ni paste when measured ｈ The ratio (V ｈ / V ｍ The Ni paste described in item 3, wherein the value is 8 or less.

[0127] [Item 5] The Ni paste according to any one of items 1 to 4, wherein the solvent includes a hydrocarbon solvent and an alcohol solvent.

[0128] [Item 6] The Ni paste according to any one of items 1 to 5, wherein the binder resin comprises a cellulose resin and a polyvinyl acetal resin.

[0129] [Item 7] The Ni paste according to any one of items 1 to 6, comprising an anionic dispersant and a nonionic dispersant as the dispersant.

[0130] [Item 8] The Ni paste according to Item 7, wherein the anionic dispersant comprises a carboxylic acid dispersant.

[0131] [Item 9] The Ni paste according to any one of items 1 to 8, wherein the dielectric particles include barium titanate.

[0132] [Item 10] The Ni paste according to any one of items 1 to 9, further comprising a secondary amine compound.

[0133] [Item 11] A method for manufacturing an electronic component, comprising applying the Ni paste described in any one of items 1 to 10 onto a substrate and firing it.

[0134] The technology disclosed herein provides a Ni paste used in gravure printing that suppresses the separation of dielectric particles.

[0135] 1 Multilayer ceramic capacitor (MLCC) 10 Multilayer chip 10a Unfired laminate 20 Dielectric layer 20a Dielectric green sheet 30 Internal electrode layer 30a Coating 40 External electrode

Claims

1. A Ni paste for gravure printing comprising Ni particles, dielectric particles, a binder resin, a solvent, and a dispersant, wherein the Ni particles are present in an amount of 35 wt% or more relative to the total Ni paste, and the ratio of the weight (wt%) of the dielectric particles to the weight (wt%) of the Ni particles (dielectric particles / Ni particles) is 0.05 or more, and when 0.5 g of the diluted paste obtained by diluting the Ni paste to a solid content concentration of 20 wt% is subjected to centrifugal sedimentation treatment by rotating under the following conditions: Temperature: 25°C; Rotation speed: 4000 rpm; Processing time: 6200 seconds, the weight W of the dielectric particles contained in 0.5 g of the diluted paste is ａ The weight W of dielectric particles contained in 0.3 g of the supernatant liquid of the diluted paste after centrifugal sedimentation in inductively coupled plasma atomic emission spectrometry, relative to (mg) ｂ Ni paste with a ratio of (mg) of 13% or less.

2. The Ni paste according to claim 1, wherein the ratio of the weight (wt%) of dielectric particles to the weight (wt%) of Ni particles (dielectric particles / Ni particles) is 0.3 or less.

3. Under conditions of 25°C, shear rate of 10,000 sec －１ The viscosity V of the Ni paste when measured ｍ The Ni paste according to claim 1 or 2, wherein the pressure is 0.3 Pa·S or less.

4. The viscosity V ｍ , the shear rate of 100 sec in an environment at 25°C －１ the viscosity V of the Ni paste measured at ｈ ratio (V ｈ / V ｍ ) is 8 or less. The Ni paste according to claim 3.

5. The Ni paste according to claim 1 or 2, wherein the solvent comprises a hydrocarbon solvent and an alcohol solvent.

6. The Ni paste according to claim 1 or 2, wherein the binder resin comprises a cellulose-based resin and a polyvinyl acetal-based resin.

7. The Ni paste according to claim 1 or 2, comprising an anionic dispersant and a nonionic dispersant as the dispersant.

8. The Ni paste according to claim 7, wherein the anionic dispersant comprises a carboxylic acid-based dispersant.

9. The Ni paste according to claim 1 or 2, wherein the dielectric particles include barium titanate.

10. The Ni paste according to claim 1 or 2, further comprising a secondary amine compound.

11. A method for manufacturing an electronic component, comprising applying the Ni paste described in claim 1 or 2 onto a substrate and firing it.

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