Ni paste for gravure printing and method for manufacturing electronic components

Abstract

An object of the present invention is to provide a Ni paste used for gravure printing, which suppresses separation of dielectric particles. 【Solution】The Ni paste according to the present disclosure contains Ni particles, dielectric particles, a binder resin, a solvent, and a dispersant. The Ni paste contains 35 wt% or more 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 0.05 or more. When centrifugal sedimentation treatment is performed on 0.5 g of a diluted paste obtained by diluting the Ni paste to a solid content concentration of 20 wt% under predetermined conditions, the weight W a (mg) of the dielectric particles contained in 0.5 g of the diluted paste, and the weight W b (mg) of the dielectric particles contained in 0.3 g of the supernatant of the diluted paste after the centrifugal sedimentation treatment in inductively coupled plasma optical emission spectrometry has a ratio of 13% or less.

Description

Technical Field

[0001] The present invention relates to a Ni paste for gravure printing and a method for manufacturing electronic components.

Background Art

[0002] In the manufacture of electronic components, a method of forming an electrode layer by applying a paste for forming an internal electrode containing conductive particles and dielectric particles onto a substrate to form a coating film and firing the coating film is widely used. As the paste for forming the internal electrode, for example, a Ni paste containing Ni particles as conductive particles, a binder resin, and dielectric particles (ceramic material) can be mentioned. As an example of such a Ni paste, for example, Patent Document 1 can be mentioned.

[0003] By the way, with the improvement in performance of various electronic devices, there is a demand for thinning, miniaturization, and high density of each electronic component mounted on the electronic device. For example, in a multilayer ceramic capacitor (MLCC), it is required to increase the capacitance while reducing the volume of the MLCC by reducing the thickness of one layer of the internal electrode layer and increasing the number of layers. Under such circumstances, in the application of the paste for forming the internal electrode layer, the gravure printing method is being used instead of the screen printing method. The gravure printing method is excellent in productivity because it has a higher printing speed than the screen printing method, and can form a thin film-like coating film with stable quality. As an example of such a gravure printing paste, for example, Patent Document 2 can be mentioned.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

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

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

Means for Solving the Problems

[0007] The Ni paste disclosed herein contains Ni particles, dielectric particles, a binder resin, a solvent, and a dispersant. The Ni paste contains 35 wt% or more 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 0.05 or more. And, with respect to 0.5 g of a diluted paste obtained by diluting the Ni paste to a solid content concentration of 20 wt%, the following conditions: Temperature: 25°C; Rotation speed: 4000 rpm; Treatment time: 6200 seconds; When centrifugal sedimentation treatment is performed by rotating at these conditions, the weight W of the dielectric particles contained in 0.5 g of the diluted paste a (mg), with respect to the weight W of the dielectric particles contained in 0.3 g of the supernatant of the diluted paste after the centrifugal sedimentation treatment in inductively coupled plasma optical emission spectrometry b (mg), the ratio is 13% or less.

[0008] In order to achieve the above object, as a result of investigations by the present inventors, it was confirmed that there is a difference in suppressing the separation of the dielectric even between Ni pastes having the same raw materials and composition. Based on such a viewpoint, as a result of further intensive investigations by the present inventors, the W of the Ni paste aW with respect to (mg) b It has been found that the ratio of (mg) serves as an index, and by setting such a ratio within a predetermined range, separation (floating) of the dielectric particles in the Ni paste is suppressed.

[0009] According to such a configuration, the W of the above Ni paste a W with respect to b By setting the ratio to 13% or less, separation of the dielectric particles in the Ni paste is preferably controlled. Therefore, according to the Ni paste of the present disclosure, it is possible to form a homogeneous coating film.

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

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

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

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

[0014] In a preferred embodiment of the Ni paste disclosed herein, as the above binder resin, it contains 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 a preferred embodiment of the Ni paste disclosed herein, it further includes a secondary amine compound.

[0019] Also, as another aspect of the technology disclosed herein, a method for manufacturing an electronic component is provided. Such a manufacturing method includes applying the above Ni paste onto a substrate and firing it. Thereby, an electronic component having a homogeneous electrode layer can be manufactured.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0021] Hereinafter, preferred embodiments of the technology disclosed herein will be described. In addition to the matters specifically mentioned in this specification (for example, the composition and properties of the Ni paste), matters other than those necessary for the implementation of the present invention (for example, the composition of electronic components, etc.) can be implemented based on the technical content taught in this specification and the general technical common sense of those skilled in the art. In this specification, the notation "X~Y (X and Y are arbitrary values)" indicating a numerical range includes the meaning of "X or more and Y or less", as well as the meaning of "preferably greater than X" and "preferably less than Y".

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

[0023] In this specification, when referring to "particles", unless specifically referring to a single particle unit, it means a population of a large number of particles (fine particles) (that is, particles). In Japanese, since it is ambiguous whether it is singular or plural, the above regulations are made to clarify the meaning of "particles (fine particles)".

[0024] In this specification, the "coating film" refers to a film-like body (dried product) obtained by drying the Ni paste at a temperature lower than the boiling points 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 the Ni paste is dried at a temperature below the boiling points of (C) binder resin and / or (E) dispersant, these components may remain in the coating film. The coating film includes all unburned (before firing) film-like bodies.

[0025] In addition, in this specification, the "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 body), wiring patterns, and solid patterns. Hereinafter, each component will be described in order.

[0026] (A) Ni particles Ni particles are materials that constitute the main component of the electrode layer after firing of the Ni paste. Ni particles impart electrical conductivity to the electrode. Note that the "Ni particles" in this specification refer to particles whose main element constituting the Ni particles is Ni. That is, the "Ni particles" in this specification include not only particles entirely composed of Ni (Ni single 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, such as core - shell particles with the surface of Ni particles coated with a noble metal such as silver), and the like. Also, "the main element constituting the Ni particles is Ni" means that among the metal elements constituting the Ni particles, the metal 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 the size and shape of the particles, are not particularly limited. The size of the particles can be appropriately selected according to, for example, the use of the Ni paste and the dimensions of the electrode layer. Considering the firing shrinkage rate, the size of the particles is preferably selected so as to fit within the minimum dimensions, such as the thickness and / or width, of the target electrode layer (e.g., the internal electrode layer). Although not particularly limited, the average particle diameter D of the Ni particles 1 may generally be several nm to several μm, for example, 10 nm to 10 μm. Note that in this specification, the "average particle diameter" refers to the particle diameter corresponding to 50% cumulative from the smaller side in the particle size distribution based on the number standard observed by an electron microscope.

[0028] As an example, for the purpose of forming the internal electrode layer of ultra - small to small MLCCs, the average particle diameter D of the Ni particles 1is smaller than the thickness (length in the lamination direction) of the internal electrode layer, and may generally be 0.5 μm or less, typically 0.4 μm or less, and preferably 0.3 μm or less. The average particle diameter D 1 is equal to or less than a predetermined value, and even in the case of a thin-film electrode layer, unevenness on the surface can be suppressed to a small level. The average particle diameter D of the Ni particles 1 is generally 0.01 μm or more, typically 0.05 μm or more, preferably 0.1 μm or more, and may be, for example, 0.15 μm or more. The average particle diameter D 1 is equal to or more than a predetermined value, the surface energy of the particles is suppressed, and aggregation in the Ni paste is suppressed. Therefore, a more homogeneous coating film can be realized.

[0029] The shape of the Ni particles may be, for example, substantially spherical, scaly (flake-like), needle-like, amorphous, or the like. Although not particularly limited, in the application of forming a thin-film electrode layer, the Ni particles may be substantially spherical. Thereby, the viscosity of the Ni paste can be maintained at a low level, and the handleability of the paste and the workability during gravure printing can be improved. In the present specification, "substantially spherical" means a form that can generally be regarded as a sphere (ball) as a whole, and the average aspect ratio is generally 1 to 2, for example, 1 to 1.5. Further, in the present specification, the "aspect ratio" means the ratio (b / a) of the length (b) of the long side to the length (a) of the short side of the particle when a rectangle circumscribing the obtained observation image is drawn by observing the Ni particles with an electron microscope. The average aspect ratio means the arithmetic mean value of the aspect ratios of a plurality of particles (for example, 100 particles).

[0030] From the perspective of providing sufficient electrical conductivity, the content ratio of Ni particles 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 still more preferably 47.5 wt% or more, based on the entire Ni paste (100 wt%). On the other hand, from the perspective of the handleability of the paste and the workability during gravure printing, the upper limit of the content ratio of Ni particles is preferably 70 wt% or less, preferably 65 wt% or less, more preferably 60 wt% or less, still more preferably 57.5 wt% or less, still more preferably 55 wt% or less, and particularly preferably 52.5 wt% or less, based on the entire Ni paste.

[0031] Also, as long as the effects of the technology disclosed herein are not significantly inhibited, metal particles other than Ni particles may be contained in the Ni paste. The type of such metal particles is not particularly limited, and one type may be used alone or two or more types may be appropriately combined from among those conventionally known, depending on, for example, the use of the electrode layer. Examples of such metal particles other than Ni particles include, for example, simple substances of base metals such as aluminum (Al), copper (Cu), and tungsten (W), simple substances of 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 containing metal particles other than Ni particles, the content ratio thereof is, for example, 2 wt% or less, preferably 1 wt% or less, based on the entire Ni paste.

[0032] (B) Dielectric particles Dielectric particles are components that are arranged between Ni particles during the firing of the Ni paste and relieve the thermal shrinkage of the Ni particles. Also, in the application of forming the internal electrode layer of an MLCC, it can also function as a co-material for improving the sintering bondability between the dielectric layer and the internal electrode layer. Although not particularly limited, the dielectric constant of the dielectric particles is typically 100 or more, and may be, for example, on the order of 1000 to 20000. However, the dielectric particles may have a relative dielectric constant of less than 100 and thus be an insulating material.

[0033] The type of dielectric particles is not particularly limited, and one type alone or a suitable combination of two or more types can be used from among conventionally known inorganic materials, for example, according to applications and the like. Examples of the dielectric particles include metal oxides having a perovskite structure represented by ABO 3 such as barium titanate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, zirconium titanate, zinc titanate, barium magnesium niobate, calcium zirconate, strontium zirconate, and other metal oxides such as titanium dioxide, titanium pentoxide, hafnium oxide, zirconium oxide, aluminum oxide, forsterite, niobium oxide, and barium neodymium titanate. As an example, in the application of forming the internal electrode layer of an MLCC, for example, strontium titanate, calcium zirconate, and the like can be preferably used. Although not limited thereto, in some preferred embodiments, it is preferable that the dielectric particles contain barium titanate particles. In the Ni paste according to the present disclosure, by including barium titanate particles as the dielectric particles, a Ni paste in which the separation of the dielectric particles is preferably suppressed can be obtained. When the dielectric particles contain barium titanate particles, the content of the barium titanate particles with respect to the entire dielectric particles can 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 (dielectric particles / Ni particles) of the weight (wt%) of the dielectric particles to the weight (wt%) of the Ni particles contained in the Ni paste 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, 0.15 or more). Thereby, heat resistance can be suitably obtained. On the other hand, although not limited thereto, from the viewpoint of forming a thin film electrode, the ratio (dielectric particles / Ni particles) of the weight (wt%) of the dielectric particles to the weight (wt%) of the Ni particles contained in the Ni paste is preferably 0.4 or less, preferably 0.35 or less, more preferably 0.3 or less, still more preferably 0.25 or less, and particularly preferably 0.2 or less.

[0035] The content rate of the dielectric particles with respect to the entire 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 still more preferably 10 wt% or more. Thereby, during firing of the Ni paste, heat shrinkage of the Ni particles can be suitably relaxed. On the other hand, although not limited thereto, from the viewpoint of electrical conductivity, the content rate of the dielectric particles with respect to the entire Ni paste (100 wt%) can 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 production method of the dielectric particles and the properties of the particles constituting the dielectric particles, such as the size and shape of the particles, are not particularly limited. The size of the particles can be appropriately selected according to, for example, the use of the Ni paste and the dimensions of the electrode layer. The size of the particles may be selected so as to fit within the minimum dimensions, such as the thickness and / or width, of the target electrode layer (for example, the internal electrode layer), taking into account the firing shrinkage rate. Although not particularly limited, the average particle diameter D of the dielectric particles 2 may generally be several nm to several μm, for example, 1 nm to 1 μm. As an example, in the application of forming the internal electrode layer of an MLCC, the average particle diameter D of the dielectric particles 2is generally 5 nm or more, typically 10 nm or more, for example 20 nm or more, and may be 50 nm or more, and is generally 0.5 μm or less, typically 0.3 μm or less, for example 0.2 μm or less, 0.1 μm or less.

[0037] Although not particularly limited, from the viewpoint of forming an electrode layer excellent in electrical conductivity, the average particle diameter D of the dielectric particles 2 is preferably smaller than the average particle diameter D of the Ni particles. That is, D 1 and D 1 and D 2 are preferably such that D 1 > D 2 . D 1 and D 2 are preferably such that (D 1 / D 2 ) ≧ 2, more preferably (D 1 / D 2 ) ≧ 3, and may be, for example, (D 1 / D 2 ) ≧ 4. When the average particle diameters are significantly different in this way, the application of the technology disclosed herein is particularly effective. Also, D 1 and D 2 may satisfy 50 ≧ (D 1 / D 2 ), may satisfy 20 ≧ (D 1 / D 2 ), and may be, for example, 10 ≧ (D 1 / D 2 ).

[0038] (C) Binder resin The binder resin is a component that adjusts the viscosity (fluidity) of the Ni paste and imparts adhesiveness to the coating film to adhere inorganic particles to each other and the inorganic particles to the substrate. The binder resin can be dissolved in the (D) solvent 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 out during firing of the coating film. The binder resin may have a decomposition temperature of 500 °C or lower, for example.

[0039] The type of the binder resin is not particularly limited, and one type can be used alone or two or more types can be appropriately combined from among the conventionally known organic compounds used for this type of application, for example, according to the application and the like. The binder resin is typically a thermoplastic resin. However, a thermosetting resin may also be used. Examples of the binder resin include organic polymer compounds such as cellulose-based resins, polyvinyl acetal-based resins, polyvinyl alcohol-based resins, acrylic-based resins, urethane-based resins, epoxy-based resins, phenol-based resins, rosin-based resins, polyester-based resins, and ethylene-based resins. Among them, from the viewpoints of improving the burn-through property during firing and the surface smoothness of the electrode layer, etc., it is preferable to include (C1) a cellulose-based resin as the binder resin. Also, from the viewpoints of improving the adhesiveness between the coating film and the base material and the integrity of the coating film, etc., it is preferable to include (C2) a polyvinyl acetal-based resin as the binder resin, and for example, it is suitable to use a combination of (C1) a cellulose-based resin and (C2) a polyvinyl acetal-based resin.

[0040] (C1) The cellulose-based resin encompasses the entire range of linear polymers (cellulose) containing β-glucose as a repeating unit and its derivatives. Typically, it can be a compound in which a part or all of the hydroxy groups in the β-glucose structure, which is the repeating unit, are substituted with alkoxy groups, and its derivatives (modified products, etc.). Note that in the alkoxy group (RO-), the alkyl group or aryl group (R) may have a part or all of it substituted with an ester group such as a carboxyl group, a nitro group, a halogen, or other organic groups. Examples of the cellulose-based resin include methyl cellulose, ethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, carboxyethyl methyl cellulose, cellulose acetate phthalate, nitrocellulose, and the like. Among them, methyl cellulose and ethyl cellulose are preferable. By including the cellulose-based resin, the workability during gravure printing can be improved, and a coating film with excellent surface smoothness can be stably formed.

[0041] The properties of the cellulose-based resin are not particularly limited. The weight average molecular weight (Mw) of the cellulose-based resin may generally be 20,000 or more, for example, 30,000 or more, 40,000 or more, or 50,000 or more. Further, the weight average molecular weight (Mw) of the cellulose-based resin may generally be 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 the "weight average molecular weight (Mw)" is the average molecular weight based on the number, and can be measured by, for example, Gel Permeation Chromatography (GPC) and calculated using a standard polystyrene calibration curve.

[0042] (C2) The polyvinyl acetal-based resin is a resin obtained by reacting an aldehyde with a polyvinyl alcohol-based resin to effect acetalization. The polyvinyl acetal-based resin has a structural unit in which continuous vinyl alcohol structural units are acetalized by an aldehyde compound, and may have one or more of the unreacted vinyl alcohol structural units and vinyl acetate structural units which are the saponification-uncompleted portions of the polyvinyl alcohol-based resin, and encompasses the entirety of polymers and their derivatives (modified products, etc.). The ratio (degree of acetalization) of the acetalized structural units in the polyvinyl acetal-based resin may be, for example, 50 mol% or more. The polyvinyl acetal-based resin is, for example, superior in adhesiveness and flexibility compared to the cellulose-based resin.

[0043] Examples of the polyvinyl acetal-based resin include polyvinyl butyral resin having a structure in which polyvinyl alcohol is acetalized with butanol. By including polyvinyl butyral resin, the shape characteristics of the coating film can be improved. The polyvinyl acetal-based resin may be a copolymer (including graft copolymerization) having the polyvinyl acetal-based resin as the main monomer (a component occupying 50% or more of the total monomers; the same shall apply hereinafter) and including a comonomer copolymerizable with the main monomer. Examples of the comonomer include ethylene, esters, (meth)acrylates, vinyl acetate, and the like.

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

[0045] Although not particularly limited, the binder resin may be composed mainly of (C2) polyvinyl acetal resin (the component that occupies the largest proportion; the same applies hereinafter). When the total of the binder resin is 100 wt%, (C2) polyvinyl acetal resin may generally occupy 50 wt% or more, for example, 60 - 80 wt%. Also, when the binder resin contains both (C1) cellulose resin and (C2) polyvinyl acetal resin at the same time, when (C1)+(C2) is 100 wt%, (C2) polyvinyl acetal resin may be generally 10 - 90 wt%, typically 20 - 80 wt%, or 50 - 70 wt%.

[0046] Although not particularly limited, from the viewpoints of the printability of the paste, the adhesion to the base material (e.g., green sheet, etc.), the shape retention of the coating film, etc., the content ratio of the binder resin is, for example, 0.1 wt% or more with respect to the entire Ni paste, preferably 0.5 wt% or more, and more preferably 1 wt% or more. On the other hand, from the viewpoints of the printability of the paste, the burnout of the resin during firing, etc., the content ratio of the binder resin is, for example, 5 wt% or less with respect to the entire Ni paste, preferably 4 wt% or less, and more preferably 3 wt% or less.

[0047] (D) Solvent The solvent is a liquid medium for dispersing inorganic particles and imparting a viscosity (fluidity) suitable for gravure printing to the Ni paste. The solvent can also function as a vehicle for dissolving the above-mentioned (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 out during the drying of the Ni paste and / or during the firing of the coating film.

[0048] The type of the solvent is not particularly limited, and one type can be used alone or two or more types can be appropriately combined according to, for example, the type of the substrate to which the Ni paste is applied and the type of the binder resin, from among the conventionally known organic solvents used for this type of application. Among them, from the viewpoint of suppressing the sheet attack phenomenon (the phenomenon in which the solvent erodes the green sheet), it is preferable that the solvent contains (D1) a hydrocarbon-based solvent. Also, from the viewpoint of the solubility of the resin, it is preferable that the solvent contains (D2) an alcohol-based solvent. Although not limited thereto, for example, it is preferable to use a combination of (D1) a hydrocarbon-based solvent and (D2) an alcohol-based solvent as the solvent.

[0049] (D1) The hydrocarbon-based solvent includes all solvents composed only of carbon and hydrogen elements. Examples of the hydrocarbon-based solvent include aromatic hydrocarbon solvents such as toluene and xylene; paraffin-based solvents such as normal paraffins and isoparaffins, naphthene-based solvents such as monocyclic naphthenes and bicyclic naphthenes, paraffin / naphthalene mixed solvents, and aliphatic hydrocarbon solvents such as mineral spirits. Although not limited thereto, from the viewpoint of suppressing the sheet attack phenomenon, it is preferable that the hydrocarbon-based solvent contains a naphthene-based solvent, and the hydrocarbon-based solvent may be mainly composed of a naphthene-based solvent.

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

[0051] Note that as the (D) solvent, solvents other than the (D1) hydrocarbon solvent and the (D2) alcohol solvent may be included. Examples of such solvents include ester solvents having an ester bond (R-C(=O)-O-R’), ether solvents having an ether bond (R-O-R’), and the like. 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, dihydroterpineol acetate, and the like. Examples of ether solvents include dipropylene glycol methyl ether, methyl cellosolve (ethylene glycol monomethyl ether), cellosolve (ethylene glycol monoethyl ether), butyl carbitol (diethylene glycol monobutyl ether), and the like.

[0052] Although not particularly limited, when the total amount of the Ni paste is 100 wt%, the content ratio of the solvent may generally be 10 to 70 wt%, typically 20 to 60 wt%, for example 30 to 50 wt%. By satisfying the above range, appropriate fluidity can be imparted to the Ni paste, and the workability during gravure printing can be improved. In addition, the self-leveling property can be improved, and a coating film excellent in surface smoothness can be stably formed even during high-speed printing.

[0053] Although not particularly limited, the solvent may be composed mainly of (D2) an alcohol-based solvent. When the total amount of the solvent is 100 wt%, the (D2) alcohol-based solvent may generally occupy 30 to 60 wt%, for example 40 to 50 wt%. Further, when the solvent contains (D1) a hydrocarbon-based solvent and (D2) an alcohol-based solvent, the (D1) hydrocarbon-based solvent may generally occupy 10 to 50 wt%, for example 15 to 45 wt% when the total amount of the solvent is 100 wt%.

[0054] Although not particularly limited, from the viewpoint of improving the storage stability of the Ni paste, the workability during gravure printing, etc., the solvent other than the (D1) hydrocarbon-based solvent may contain a high-boiling solvent having a boiling point of generally 100°C or higher, for example 200°C or higher. Also, considering the viewpoint of improving productivity by quickly drying the coating film, it is preferable to use a high-boiling solvent having a boiling point of generally 100 to 300°C, for example 200 to 250°C, preferably 230°C or lower as the main component. The high-boiling solvent may generally occupy 50 wt% or more, for example 90 wt% or more when the total amount of the solvent other than the (D1) hydrocarbon-based solvent is 100 wt%, and substantially the entire solvent (95 wt% or more) may be composed of the high-boiling solvent.

[0055] (E) Dispersant The dispersant is for uniformly dispersing the above-mentioned inorganic particles, that is, (A) Ni particles and (B) dielectric particles, in the Ni paste and suppressing the aggregation of these components.

[0056] The type of the dispersant and the like is not particularly limited, and one or more types can be used as needed from various known dispersants. Typically, those having sufficient compatibility with the solvent can be appropriately selected and used. There can be various ways of classifying the dispersant. For example, anionic dispersants, cationic dispersants, nonionic dispersants, amphoteric dispersants, etc. can be mentioned. Although not limited thereto, it is preferable that the dispersant includes (E1) an anionic dispersant and (E2) a nonionic dispersant. For example, it is preferable to use a combination of (E1) an anionic dispersant and (E2) a nonionic dispersant.

[0057] (E1) The anionic dispersant is, for example, a dispersant having an anionic functional group. The anionic dispersant adheres to the surface of the particles via an anionic functional group, for example, causing steric hindrance. Therefore, aggregation between the ceramic particles can be suppressed, and thus the long-term stability of the ink can be improved.

[0058] As the anionic dispersant, conventionally known anionic dispersants used for this kind of application can be used without particular limitation. As the anionic dispersant, for example, a dispersant having one or more carboxyl groups (COO - group) in the molecule (carboxylic acid-based dispersant), a dispersant having one or more phosphonic acid groups (PO 3 - group, PO 3 2- group) in the molecule (phosphoric acid-based dispersant), a dispersant having one or more sulfonic acid groups (SO 3 - group, SO 3 2- group) in the molecule (sulfonic acid-based dispersant), etc. can be mentioned. Among them, as the anionic dispersant, carboxylic acid-based dispersants can be preferably used. As the carboxylic acid-based dispersant, for example, monocarboxylic acid-based dispersants, dicarboxylic acid-based dispersants, polycarboxylic acid-based dispersants, polycarboxylic acid partial alkyl ester-based dispersants, etc. can be mentioned.

[0059] The weight average molecular weight (Mw) of the anionic dispersant may generally be 500 or more, for example, 1000 or more, 3000 or more, 5000 or more, 8000 or more, or 10,000 or more. Also, the weight average molecular weight (Mw) of the anionic dispersant may generally be about 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 more, the effect of enhancing the uniform dispersibility of Ni particles and dielectric particles can be more effectively exerted.

[0060] (E2) The nonionic dispersant is a dispersant that does not have a group that ionizes when dissolved in water. For this reason, it is less likely to adhere to the surface of inorganic particles compared to an anionic dispersant having an ionizable group. On the other hand, the nonionic dispersant has the effect of adsorbing to particles and other dispersants, and improving the dispersion effect by other dispersants without adversely affecting the dispersion effect by other dispersants. Thereby, the dispersibility of the inorganic particles in the Ni paste can be further improved. Regarding the nonionic dispersant, a conventionally known nonionic dispersant can be used without particular limitation. Examples of such nonionic dispersants include ether-based dispersants, ester-based dispersants, ether-ester-based dispersants, nitrogen-containing dispersants, and the like.

[0061] Although not particularly limited, when the total of the Ni paste is 100 wt%, the content ratio of the dispersant is generally 0.01 wt% or more, for example, 0.05 wt% or more, and preferably 0.1 wt% or more. Thereby, the dispersant can be sufficiently made to act on the inorganic particles. Also, from the viewpoint of forming an electrode layer excellent in electrical conductivity and denseness, the content ratio of the dispersant 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) Thickeners inhibitor (F) The thickening inhibitor is for suppressing the increase in the viscosity of the Ni paste over time. Although not limited thereto, the Ni paste disclosed herein can contain a thickening inhibitor. According to such a configuration, the thickening of the Ni paste after production can be favorably suppressed.

[0063] The type of the thickening inhibitor is not particularly limited, and one or more kinds can be used as needed from various known thickening inhibitors. Although not limited thereto, it is preferable to contain a secondary amine compound as the thickening inhibitor. The secondary amine compound has the general formula: NHR 1 R 2 ; and is a compound in which two hydrogen atoms (H) of ammonia (NH 3 ) are substituted with hydrocarbon-containing functional groups R 1 and R 2 .

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

[0065] Although not particularly limited, when the total amount of the Ni paste is 100 wt%, the content ratio of the thickening inhibitor is generally 0.01 wt% or more, for example, it may be 0.05 wt% or more, and preferably 0.1 wt% or more. Thereby, the thickening inhibitory effect can be suitably obtained for the Ni paste. On the other hand, from the viewpoint of forming an electrode layer excellent in electrical conductivity and denseness, the content ratio of the thickening inhibitor is generally 5 wt% or less, for example, it may be 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 can contain various additives known to be usable in general Ni pastes as long as the effects of the technology of the present disclosure are not significantly impaired. Examples of such additives include, for example, viscosity modifiers, defoamers, plasticizers, leveling agents, pH adjusters, stabilizers, antioxidants, preservatives, colorants (pigments, dyes, etc.). These additives can be used singly or in appropriate combinations of two or more as needed.

[0067] The additives can be contained in an appropriate ratio according to the purpose of addition and the like. Although not particularly limited, when the total amount of the Ni paste is 100 wt%, the content ratio of the additives is preferably suppressed to generally 5 wt% or less, typically 3 wt% or less, for example, 1 wt% or less. Thereby, an electrode layer excellent in electrical conductivity and denseness can be suitably realized.

[0068] <Properties of Ni Paste> The Ni paste disclosed herein is prepared so that floating (separation) of the dielectric particles in the Ni paste is suppressed. Specifically, with respect to 0.5 g of a diluted paste obtained by diluting the Ni paste disclosed herein to a solid content concentration of 20 wt%, the following conditions: Temperature: 25°C; Rotation speed: 4000 rpm; Treatment time: 6200 seconds; When centrifugal sedimentation treatment is performed by rotating at, the weight W of the dielectric contained in 0.5 g of the above diluted pastea The weight W of the dielectric contained in 0.3 g of the supernatant of the diluted paste after the centrifugation treatment in inductively coupled plasma (ICP) emission spectrometry (ICP analysis) with respect to (mg). b It is characterized in that the ratio is 13% or less. The solvent used for adjusting the diluted paste is the solvent contained in the Ni paste. When two or more solvents are contained in the Ni paste, the diluted paste is prepared using the solvent with the highest content ratio among the solvents contained in the Ni paste, and the above measurement is performed. Note that the "weight W of the dielectric contained in 0.5 g of the diluted paste a (mg)" can be calculated from the weight ratio (wt%) of the dielectric contained in the Ni paste before dilution. Also, the "weight W of the dielectric contained in 0.3 g of the supernatant of the diluted paste b (mg)" can be calculated based on the content rate of the metal element constituting the dielectric particles in the supernatant of the diluted paste after the centrifugation treatment obtained by ICP analysis. Depending on the detection range of the apparatus used for ICP analysis, the supernatant may be further diluted with a solvent and then subjected to ICP analysis.

[0069] Typically, gravure printing has a higher printing speed than screen printing. Therefore, if the viscosity of the Ni paste is adjusted to the same level as during screen printing, the surface of the coating film may become rough and the unevenness may increase. This can lead to distortion of the laminated structure and may cause problems such as short-circuit defects. For this reason, the Ni paste for gravure printing needs to be adjusted to a lower viscosity than that for screen printing. However, as a Ni paste adjusted to a low viscosity for gravure printing, separation (floating) of the dielectric particles in the Ni paste may occur. When a coating film is formed using a Ni paste in which the dielectric particles are separated, it is difficult to form a uniform coating film, so there is a risk of a decrease in yield.

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

[0071] Although not particularly limited, the lower the viscosity of the Ni paste, the more preferably it can be adopted for gravure printing applications with a high printing speed. Therefore, in an environment of 25°C, the viscosity V of the Ni paste when measured at a shear rate of 10,000 sec -1 is preferably 0.3 Pa·S or less, more preferably 0.25 Pa·S or less, and even more preferably 0.2 Pa·S or less from the viewpoint of accelerating the printing speed and improving productivity. On the other hand, from the viewpoint of suppressing printing sagging and the like and improving workability, the viscosity V m may be adjusted to, for example, 0.02 Pa·s or more and 0.05 Pa·s or more. The viscosity of the Ni paste can be adjusted, for example, by the type and content ratio of the binder resin, the type and content ratio of the dispersant, the type and content ratio of the solvent, and the addition of other additives (for example, viscosity modifiers, thickeners). Also, the viscosity of the Ni paste (V m and V m and V h ) can be measured using a rotational rheometer.

[0072] Although not particularly limited, in an environment of 25°C, the viscosity V of the Ni paste when measured at a shear rate of 100 sec -1 is generally preferably adjusted to 3.0 Pa·s or less, 2.5 Pa·s or less, 2.0 Pa·s or less, 1.5 Pa·s or less, 1.0 Pa·s or less. The viscosity V h may be adjusted to, for example, 0.1 Pa·s or more, 0.2 Pa·s or more, 0.3 Pa·s or more. h

[0073] ​ Although not limited thereto, viscosity V m with respect to viscosity V h ratio (V h / V m ) is preferably 8 or less, more preferably 7.5 or less, still more preferably 7 or less, still more preferably 6.5 or less, and particularly preferably 6 or less. Thereby, the storage stability and handleability of the Ni paste can be improved.

[0074] <Method for manufacturing Ni paste> The Ni paste disclosed herein can be prepared, for example, by preparing a vehicle in which a binder and a solvent are mixed, and mixing and kneading Ni particles and dielectric particles in the vehicle. As an example of the method for manufacturing the Ni paste, a dielectric particle slurry in which dielectric particles are dispersed in a solvent is prepared, 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 subjected to a dispersion treatment. Thereby, the Ni particles and the dielectric particles can be more uniformly dispersed in the solvent.

[0075] Here, in order to control the ratio of W a with respect to W b to a predetermined value or less, when the stirring and mixing device for performing the dispersion treatment on the inorganic particle slurry and the vehicle is a conventional general one, the dispersion treatment intensity tends to become too high. When the dispersion treatment intensity is too high, the obtained Ni paste has W a with respect to W bThe ratio may increase. The reason for this is not clear, but as one factor, it is considered that when the intensity of dispersion treatment becomes too high, the dispersant adhering (adsorbing) to the particle surface falls off, thereby reducing the dispersibility of the dielectric particles. Therefore, although the stirring conditions cannot be generally stated because they depend on the materials used and their properties, etc., when using a known stirring and mixing device, it is preferable to prepare the paste under stirring conditions with a generally relaxed intensity of dispersion treatment. For example, as an example, if the intensity of dispersion treatment in the conventional dispersion treatment for the inorganic particle slurry and the vehicle is set to 1, 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 intensity of dispersion treatment 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] Also at this time, regarding the stirring and mixing device for performing the dispersion treatment on the inorganic particle slurry and the vehicle, it is advisable to perform the stirring and dispersion treatment using a media-less stirring device or dispersion device. Note that a media-less stirring device or dispersion device refers to a stirring or dispersion device that does not have a hard medium (also referred to as a grinding member, movable member, media, etc.) for exerting a stirring and dispersion action such as impact on the fluid to be stirred or dispersed. The driving force of this media-less stirring or dispersion device is, for example, high-speed fluids such as compressed air, steam, heated air currents, ultrasonic waves, cavitation bubbles, etc., and the stirring or dispersion action is manifested by the impact, impulse, mutual collision, mutual friction, etc. of the particles caused by such a driving force. For example, a planetary mixer, a planetary mill, a pneumatic grinding mill, a jet mill, an ultrasonic jet mill, a cross jet mill, etc. are exemplified. According to this media-less stirring and dispersion device, the dispersion treatment can be performed under conditions with a relaxed intensity of dispersion treatment compared to a dispersion device equipped with a hard medium.

[0077] In the preparation of the vehicle, the dielectric particle slurry, and the inorganic particle slurry, various conventionally known stirring devices and dispersing devices can be used. For example, the above-mentioned mediumless stirring device or dispersing device may be used, or a medium-type stirring device or dispersing device may be used. As the medium-type stirring and dispersing device, for example, a ball mill, a bead mill, a colloid mill, a hammer mill, a mortar, a disk crusher, a roller mill, etc. can be appropriately used.

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

[0079] <Multilayer ceramic capacitor> Hereinafter, as an example of an electronic component manufactured using the Ni paste disclosed herein, the configuration of a multilayer ceramic capacitor (MLCC) will be described. FIG. 1 is a cross-sectional view schematically showing the configuration of the MLCC1. The MLCC1 is a chip-type capacitor in which a large number of dielectric layers 20 and internal electrode layers 30 are alternately and integrally laminated. A pair of external electrodes 40 are provided on the side surface of the laminated chip 10 composed of the dielectric layer 20 and the internal electrode layer 30. As an example, the internal electrode layers 30 are alternately connected to different external electrodes 40 in the lamination order. As a result, capacitor structures each composed of a dielectric layer 20 and a pair of internal electrode layers 30 sandwiching the dielectric layer 20 are connected in parallel, and a small-sized and large-capacity MLCC1 is constructed. The dielectric layer 20 of the MLCC1 is composed of, for example, a dielectric material. The internal electrode layer 30 is composed of a fired body of the Ni paste disclosed herein.

[0080] Also, as another aspect of the technology disclosed herein, a method for manufacturing an electronic component is provided. Such a manufacturing method includes applying and firing the Ni paste disclosed herein onto a substrate. Hereinafter, an example of a method for manufacturing an electronic component using the Ni paste of the present disclosure will be described taking MLCC1 as an example. FIG. 2 is a cross-sectional view schematically showing the configuration of an unfired laminate 10a (unfired multilayer chip 10).

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

[0082] (Substrate preparation step) In the substrate preparation step, a substrate to which the Ni paste is to be applied is prepared. Here, a dielectric green sheet as the substrate is prepared. For example, a ceramic powder as a dielectric material, a binder resin, a solvent, etc. are mixed to prepare a paste for forming a dielectric layer. Next, the prepared paste is applied in a thin layer on a carrier sheet by a doctor blade method or the like to prepare an unfired dielectric green sheet 20a.

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

[0084] (Laminated compact production step) In the process of manufacturing the laminated and pressed body, a plurality of (for example, several hundred to several thousand) dielectric green sheets 20a with the prepared coating film 30a are laminated and pressed. Thereby, a laminated and pressed body is manufactured. The laminated and pressed body is cut into a chip shape as required. Since the coating film 30a has small surface irregularities, even when laminated or pressed, the distortion of the laminated structure is unlikely to occur. Also, since the coating film 30a has good adhesion to the dielectric green sheet 20a, problems such as cracking or peeling of the coating film 30a are unlikely to occur even when laminated, pressed, or cut. Thereby, the unfired laminate 10a can be stably obtained.

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

[0086] Note that 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, for example, (C) binder resin, (D) solvent, and (E) dispersant can disappear. Such a firing temperature can be, for example, about 1000 to 1300 °C.

[0087] Thereafter, an external electrode 40 is formed by applying and baking an external electrode material on the side surface of the laminated chip 10. In the above manner, a high-quality MLCC 1 can be manufactured.

[0088] Note that the uses of the Ni paste disclosed herein are not limited to the MLCCs described above. As other examples of electronic components in which the Ni paste disclosed herein can be used, for example, chip inductors, high-frequency filters, high-temperature co-fired ceramic (HTCC) substrates, low-temperature co-fired ceramic (LTCC) substrates, etc. can be mentioned.

[0089] Hereinafter, several examples related to the technology disclosed herein will be described, but it is not intended to be limited to those shown in the examples according to the present disclosure.

[0090] <Preparation of Ni Paste> Here, the Ni paste according to each example for each evaluation was prepared. In this test, during the preparation of the Ni paste, the intensity of the dispersion treatment was adjusted to four levels (dispersion treatment intensities A to D) by changing the apparatus, the rotation speed, and the peripheral speed. Note that the dispersion treatment intensities are in the order of A > B > C > D. In other words, the dispersion treatment intensity A is the strongest, and the dispersion treatment intensity D is the weakest. Note that the stirring under general conditions by a conventionally widely used stirring apparatus is generally at an intensity near the dispersion treatment intensity A.

[0091] (Example 1) Here, the Ni paste of formulation I shown in Table 1 was prepared according to the following procedure. In Table 1, the content ratios of Ni particles and dielectric particles in the Ni paste are shown as 'Solid content concentration (wt%)'. Also, 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] In Composition I, Ni particles with an average particle diameter of 0.2 μm were used. Also, in Composition I, barium titanate particles with an average particle diameter of 0.1 μm were used as dielectric particles. As the binder resin, ethyl cellulose (weight-average molecular weight (Mw): 77,000) and polyvinyl butyral (weight-average molecular weight (Mw): 85,000) were mixed and used. As the solvent, a hydrocarbon-based solvent (naphthalene-based solvent) and an alcohol-based solvent (dihydroterpineol) were used. As the dispersant, a carboxylic acid-based dispersant (a polycarboxylic acid-based dispersant, weight-average molecular weight (Mw): 13,000) and a nonionic dispersant were each used. Also, a secondary amine compound was used as a thickening inhibitor.

[0093] First, barium titanate particles, dihydroterpineol, and a carboxylic acid-based dispersant were mixed, and a dispersion treatment was performed using a media mill to prepare a dielectric particle slurry. Note that the weight ratio (wt%) of each material contained in the dielectric particle slurry was such that barium titanate particles:dihydroterpineol:carboxylic acid-based dispersant = 50:48:2, and each material was blended accordingly.

[0094] On the other hand, ethyl cellulose, polyvinyl butyral, and dihydroterpineol were mixed to separately prepare a vehicle. Note that the weight ratio (wt%) of each material contained in the vehicle was such that ethyl cellulose:polyvinyl butyral:dihydroterpineol = 8:12:80, and each material was blended accordingly.

[0095] Next, when the total adjusted Ni paste was set to 100 wt%, each material was charged into a stirrer so that Ni particles, the above dielectric particle slurry, and the naphthalene-based solvent were 50 wt%, 25 wt%, and 5 wt% respectively. Then, a mixing treatment was performed with the stirrer, and then a dispersion treatment was performed with a bead mill. In this way, an inorganic particle slurry was obtained.

[0096] Next, to the above inorganic particle slurry, the vehicle prepared above, a naphthenic solvent, dihydroterpineol, a nonionic dispersant, and a secondary amine compound were added. At this time, when the entire adjusted Ni paste was set to 100 wt%, the inorganic particle slurry, the vehicle, the naphthenic solvent, dihydroterpineol, the nonionic dispersant, and the secondary amine compound were blended so as to be 80 wt%, 13 wt%, 3 wt%, 3.2 wt%, 0.2 wt%, and 0.6 wt%, respectively. Then, using a bead mill with φ0.2 mm beads, a dispersion treatment was performed 20 passes at a stirring speed of 12 m / s (dispersion treatment intensity A). Thereby, the Ni paste according to Example 1 was prepared.

[0097] (Example 2) In Example 2, during the preparation of the Ni paste, using a bead mill with φ0.2 mm beads, a dispersion treatment was performed 20 passes at a stirring speed of 8 m / s (dispersion treatment intensity B), thereby preparing the Ni paste. The conditions other than this point and the formulation of the Ni paste (formulation I) were the same as in Example 1. Thereby, the Ni paste of Example 2 was obtained.

[0098] (Example 3) In Example 3, during the preparation of the Ni paste, using a planetary mill, a dispersion treatment was performed for 240 seconds at a rotation speed of 781 rpm and a revolution speed of 1420 rpm (dispersion treatment intensity C), thereby preparing the Ni paste. The conditions other than this point and the formulation of the Ni paste (formulation I) were the same as in Example 1. Thereby, the Ni paste of Example 3 was obtained.

[0099] (Example 4) In Example 4, during the preparation of the Ni paste, using a planetary mill, a dispersion treatment was performed for 240 seconds at a rotation speed of 385 rpm and a revolution speed of 700 rpm (dispersion treatment intensity D), thereby preparing the Ni paste. The conditions other than this point and the formulation of the Ni paste (formulation I) were the same as in Example 1. Thereby, the Ni paste of Example 4 was obtained.

[0100] (Example 5) In Example 5, instead of Composition I, the Ni paste of Composition II shown in Table 1 was adjusted. In Composition II, Ni particles with an average particle diameter of 0.18 μm were used. Also, in Composition II, barium titanate particles with an average particle diameter of 0.05 μm were used as the dielectric particles. Other materials were the same as in Composition I.

[0101] First, barium titanate particles, dihydroterpineol, and a carboxylic acid-based dispersant were mixed to prepare a dielectric particle slurry. In Example 5, the weight ratio (wt%) of each material contained in the dielectric particle slurry was the same weight ratio as in Example 1 (Composition I). Also, the dispersion conditions of the dielectric particle slurry were the same as in Example 1.

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

[0103] Next, when the total weight of the adjusted Ni paste was set to 100 wt%, each material was put into a stirrer so that the Ni particles, the above dielectric particle slurry, dihydroterpineol, and the naphthenic solvent were 50 wt%, 10 wt%, 12 wt%, and 5 wt% respectively. Then, a mixing process was performed by the stirrer, and then a dispersion process was performed using a bead mill. In this way, an inorganic particle slurry was obtained.

[0104] Next, the above-prepared vehicle, naphthenic solvent, dihydroterpineol, carboxylic acid-based dispersant, nonionic dispersant, and secondary amine compound were added to the above inorganic particle slurry. At this time, when the total weight of the adjusted Ni paste was set to 100 wt%, the inorganic particle slurry, vehicle, naphthenic solvent, dihydroterpineol, carboxylic acid-based dispersant, nonionic dispersant, and secondary amine compound were blended so as to be 77 wt%, 14 wt%, 5 wt%, 3.1 wt%, 0.2 wt%, 0.2 wt%, and 0.5 wt% respectively. Then, a Ni paste was prepared by performing the same dispersion process (dispersion process intensity A) 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, the Ni paste of Formulation II shown in Table 1 was prepared. In Example 6, the preparation conditions of the dielectric particle slurry, the vehicle, and the inorganic particle slurry were the same as those in Example 5. On the other hand, in Example 6, when the inorganic particle slurry, the vehicle prepared above, the naphthenic solvent, dihydroterpineol, the carboxylic acid-based dispersant, the nonionic dispersant, and the amine-based additive were added and dispersion treatment was performed, the same dispersion treatment (dispersion treatment intensity B) as in Example 2 was performed 20 passes to prepare the Ni paste.

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

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

[0108]

Table 1

[0109] <Measurement of paste viscosity> Using the rotational vibration rheometer MARS iQ AIR manufactured by HAAKE, the viscosities of the Ni pastes in Examples 1 to 8 were measured. The measurement conditions are as follows. Viscosity V -1 at a shear rate of 10,000 sec m (Pa·S), and viscosity V -1 at a shear rate of 100 sec h (Pa·S) are shown in Table 2 respectively. Also, the ratio of viscosity V m to viscosity V h (V h / V m ) is shown in the column of 'Viscosity ratio (V h / V m )' in Table 2. Measurement mode: Shear rate dependence measurement Sensor: Cone plate (φ35 mm, angle 0.5°) Measurement temperature: 25 °C Gap: 0.027 mm Shear rate: 10,000 to 0.01 s -1 Measurement time: 3 minutes

[0110] [Evaluation of the dispersibility of dielectric particles] Here, the dispersibility of the dielectric particles (barium titanate particles) in the Ni paste of each example was evaluated. First, a diluted paste was prepared by diluting the Ni paste of each example so that the solid content concentration became 20 wt%. Dihydroterpineol was used as the solvent for preparing the above diluted paste. When diluting, in order not to cause so-called solvent shock, the solvent was dropped and mixed with a burette while stirring the Ni paste. Specifically, 10 g of the Ni paste was weighed into a 100 mL beaker, and while stirring the Ni paste in the beaker using a small stirrer (using 6 blades, rotation speed of about 200 rpm), the solvent was added in about 2 mL portions at intervals of about 5 seconds. The amount of solvent added was 21.25 g for 10 g of the Ni paste in Examples 1 to 4 and 18.6 g for 10 g of the Ni paste in Examples 5 to 8.

[0111] Centrifugation was performed on the diluted paste prepared above using a dispersion stability analyzer (LUMiFuge manufactured by LUM GmbH). First, 0.5 g of the diluted paste was weighed and slowly filled into a disposable sample cell made of polyamide in the shape of a square tube for the analyzer from the bottom of the cell, and then capped. Such an operation was performed on the diluted paste of each example. Next, the sample cell containing the diluted paste was horizontally set on the rotor of the dispersion stability analyzer (so that the longitudinal direction of the cell coincides with the centrifugal direction), and centrifugation was performed under the following conditions. Temperature: 25 °C Rotation speed: 4000 rpm Treatment 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 items of 'Dielectric particle concentration' and 'Weight (W a ) of dielectric particles contained in 0.5 g of the diluted paste' in the 'Diluted paste' column of Table 2, respectively.

[0113] After centrifugation, 0.3 g of the supernatant of the diluted paste in the sample cell was taken out. 2 g of dihydroterpineol was added to 0.3 g of the taken-out supernatant of the diluted paste for dilution to prepare a sample for ICP analysis. For the sample for ICP analysis, an ICP measuring device (5800 ICP-OES manufactured by Agilent) was used to measure the mass concentrations of Ba and Ti in the sample for ICP analysis of each example, and convert them into the barium titanate concentration (ppm) in the sample for ICP analysis. The calculated barium titanate concentration is shown in 'Barium titanate concentration in the sample for ICP analysis' in Table 2. Furthermore, from such results, the amount (mg) of barium titanate (dielectric particles) in 0.3 g of the supernatant (that is, before being diluted as the sample for ICP analysis) was calculated. Such results are shown in 'Weight (W b ) of dielectric particles contained in 0.3 g of the supernatant' in Table 2.

[0114] The weight W of the dielectric particles contained in 0.5 g of the diluted paste calculated above a (mg) and the weight W of the dielectric particles in 0.3 g of the supernatant b (mg) are used to calculate the weight W of the dielectric particles contained in 0.5 g of the diluted paste a (mg) with respect to the weight W of the dielectric particles contained in 0.3 g of the supernatant of the diluted paste after the centrifugal sedimentation treatment in the ICP b (mg) ratio (W b / W a ×100) was calculated. The results are shown in the 'Ratio of W a to W b ' in Table 2.

[0115] <Observation of the coating film by SEM> (Examples 1 to 8) First, the Ni paste of each example was applied onto a PET substrate using an applicator to a thickness of about 250 μm 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 20 kV and the observation magnification was 10,000 times. The SEM observation images of the Ni paste coating films of each example obtained are shown in Figure 3.

[0116] <Evaluation of the dispersion degree index of Ni particles> (Examples 1 to 8) Here, the dispersibility of Ni particles in the coating films according to Examples 1 to 8 obtained above was evaluated. First, based on the SEM observation images obtained above, the dispersion degree index of the conductive powder was calculated according to the dispersion evaluation method disclosed in JP-A-2015-7542. That is, first, the SEM observation image was binarized with a predetermined threshold value to generate an evaluation image. FIG. 4 is a conceptual diagram for explaining the calculation method of the dispersion degree index. Next, the evaluation image was partitioned into equal sizes until it reached a predetermined number of partitions, and for each partition size, the coefficient of variation CVb of the evaluation image and the coefficient of variation CVa at complete separation were calculated. The coefficient of variation CVb of the evaluation image was calculated based on the area value x and the standard deviation σ of the object (for example, the white portion after binarization representing the conductive powder). The coefficient of variation CVa at complete separation was calculated based on the area value of the object assuming that the object and the non-object other than the object were completely separated. Here, the evaluation image was divided until the coefficient of variation CVb of the evaluation image became the same value as the coefficient of variation CVa at complete separation. Also, for each partition size, the coefficient of variation CVc at complete mixing was calculated based on the area value of the object assuming that the object and the non-object other than the object were completely mixed.

[0117] Next, the partition size and the coefficient of variation CVb of the evaluation image were plotted on two-dimensional coordinates, and the values of the coefficient of variation CVb of the evaluation image were connected by a straight line between adjacent partition sizes to graph the "first relationship b" in FIG. 4. Similarly, the partition size and the coefficient of variation CVa at complete separation were plotted on two-dimensional coordinates, and the values of the coefficient of variation CVa at complete separation were connected by a straight line between adjacent partition sizes to graph the "second relationship a" in FIG. 4. Also, the partition size and the coefficient of variation CVc at complete mixing were plotted on two-dimensional coordinates, and the values of the coefficient of variation CVc at complete mixing were connected by a straight line between adjacent partition sizes to graph the "third relationship c" in FIG. 4.

[0118] Next, in the first relationship b, the second relationship a, and the third relationship c, the integral values in the range from the minimum value of the partition size (i.e., the maximum value of the number of divisions) to the maximum value of the partition size (i.e., the minimum value of the number of divisions) were calculated respectively. That is, as shown in FIG. 4, the area surrounded by the first relationship b and the horizontal axis was defined as B, the area surrounded by the second relationship a and the horizontal axis was defined as A, and the area surrounded by the third relationship c and the horizontal axis was defined as C. And the following formula: Dispersion index α [%] = (1 - (B - C) / (A - C)) × 100; was used to calculate the dispersion index. The results are shown in the column of 'Dispersion index α' in Table 2. Note that the closer this dispersion index α is to 100%, the better the dispersibility of the Ni particles in the coating film (i.e., the Ni particles are highly dispersed and close to a completely mixed state).

[0119]

Table 2

[0120] As shown in Table 2, even if the raw materials used are the same, by changing the preparation method, there is a difference in the ratio of W a to W b of the Ni paste. And as shown in FIG. 3, for the Ni pastes according to Examples 3 to 4, the obtained coating films were more homogeneous than those of the Ni pastes according to Examples 1 to 2. Similarly, for Examples 7 to 8, the obtained coating films were also more homogeneous than those of the Ni pastes according to Examples 5 to 6. From this, it was found that by setting the ratio of W a to W b of the Ni paste to 13% or less, the separation of the dielectric particles in the Ni paste was suppressed, and a homogeneous coating film could be obtained. Note that as shown in Table 2, almost no change in the dispersion index α due to the change in the preparation method was observed. In other words, for the Ni pastes of Examples 3 to 4 and Examples 7 to 8, it is considered that the separation of the dielectric particles can be suppressed while maintaining the dispersibility of the Ni particles.

[0121] The preferred embodiments of the technology disclosed herein have been described above. However, the above-described embodiments are merely examples, and the present invention can be implemented in various other forms. This disclosure can be implemented based on the content disclosed herein and common general knowledge in the art. The technology described in the claims includes various modifications and changes to the embodiments exemplified above. For example, it is also possible to combine some of the above-described embodiments or replace them with other modified forms. Further, if the technical features are not described as essential, they can be appropriately deleted.

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

[0123] [Item 1] A gravure printing Ni paste containing Ni particles, dielectric particles, a binder resin, a solvent, and a dispersant, containing 35 wt% or more of the above Ni particles based on the entire Ni paste, wherein the ratio (dielectric particles / Ni particles) of the weight (wt%) of the above dielectric particles to the weight (wt%) of the above Ni particles is 0.05 or more, For 0.5 g of a diluted paste obtained by diluting the Ni paste to a solid content concentration of 20 wt%, the following conditions: Temperature: 25°C; Rotation speed: 4000 rpm; Treatment time: 6200 seconds; When centrifugal sedimentation treatment is performed by rotating under the above conditions, the weight W a (mg) of the dielectric particles contained in 0.5 g of the diluted paste, with respect to the weight W b (mg) of the dielectric particles contained in 0.3 g of the supernatant of the diluted paste after the centrifugal sedimentation treatment in inductively coupled plasma optical emission spectrometry, the ratio is 13% or less, Ni paste.

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

[0125] [Item 3] In an environment of 25 °C, the shear rate is 10,000 sec -1 At this time, the viscosity V of the above Ni paste measured m is 0.3 Pa·S or less, The Ni paste according to Item 1 or 2.

[0126] [Item 4] The above viscosity V m For, in an environment of 25 °C, the shear rate is 100 sec -1 At this time, the viscosity V of the above Ni paste measured h Ratio of (V h / V m ) is 8 or less, The Ni paste according to Item 3.

[0127] [Item 5] As the above solvent, a hydrocarbon-based solvent and an alcohol-based solvent are included, The Ni paste according to any one of Items 1 to 4.

[0128] [Item 6] As the above binder resin, a cellulose-based resin and a polyvinyl acetal-based resin are included, The Ni paste according to any one of Items 1 to 5.

[0129] [Item 7] As the above dispersant, an anionic dispersant and a nonionic dispersant are included, The Ni paste according to any one of Items 1 to 6.

[0130] [Item 8] As the above anionic dispersant, a carboxylic acid-based dispersant is included, The Ni paste according to Item 7.

[0131] [Item 9] As the above dielectric particles, barium titanate is included, The Ni paste according to any one of Items 1 to 8.

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

[0133] [Item 11] A method for manufacturing an electronic component, which includes applying the Ni paste according to any one of Items 1 to 10 onto a substrate and firing it.

Explanation of Signs

[0134] 1 Multilayer ceramic capacitor (MLCC) 10 Multilayer chip 10a Unfired laminate 20 Dielectric layer 20a Dielectric green sheet 30 Internal electrode layer 30a Coating film 40 External electrode

Claims

1. A Ni paste for gravure printing comprising Ni particles, dielectric particles, a binder resin, a solvent, and a dispersant, The Ni particles are contained in an amount of 35 wt% or more based on the entire Ni paste, a 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; The Ni paste was diluted to a solid content concentration of 20 wt % and 0.5 g of the diluted paste was subjected to the following conditions: Temperature: 25℃; Rotation speed: 4000 rpm; Processing time: 6200 seconds; When a centrifugal sedimentation process is performed by rotating the diluted paste at a speed of 1000 rpm, the weight W of the dielectric particles contained in 0.5 g of the diluted paste is ａ (mg) of the weight W of the dielectric particles contained in 0.3 g of the supernatant of the diluted paste after the centrifugal sedimentation treatment in the inductively coupled plasma optical emission spectrometry. ｂ (mg) is 13% or less; Ni paste.

2. 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; The Ni paste according to claim 1 .

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

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

5. The solvent includes a hydrocarbon solvent and an alcohol solvent. The Ni paste according to claim 1 or 2.

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

7. The dispersant includes an anionic dispersant and a nonionic dispersant. The Ni paste according to claim 1 or 2.

8. The anionic dispersant includes a carboxylic acid dispersant. The Ni paste according to claim 7.

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

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

11. A method for producing an electronic component, comprising applying the Ni paste according to claim 1 or 2 onto a substrate and firing the substrate.

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