KR102613114B1 - Conductive pastes, electronic components, and multilayer ceramic capacitors - Google Patents

Abstract

A conductive paste having a viscosity suitable for gravure printing and excellent paste dispersibility is provided. A conductive paste containing conductive powder, a dispersant, a binder resin, and an organic solvent, wherein the dispersant contains an alkyl phosphoric acid ester compound that is an acid-based dispersant, the binder resin contains an acetal-based resin, and the organic solvent is a glycol ether-based solvent. Provided by a conductive paste, etc. containing.

Description

Conductive pastes, electronic components, and multilayer ceramic capacitors

The present invention relates to conductive pastes, electronic components, and multilayer ceramic capacitors.

With the miniaturization and increase in performance of electronic devices such as mobile phones and digital devices, there is a demand for miniaturization and higher capacity for electronic components including multilayer ceramic capacitors. The multilayer ceramic capacitor has a structure in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately stacked, and by thinning these dielectric layers and internal electrode layers, miniaturization and high capacity can be achieved.

A multilayer ceramic capacitor is manufactured, for example, as follows. First, on the surface of a dielectric green sheet containing a dielectric powder such as barium titanate (BaTiO ₃ ) and a binder resin, a paste for internal electrodes (conductive paste) containing conductive powder, a binder resin, and an organic solvent, etc. is applied, It is printed with a predetermined electrode pattern and dried to form a dry film. Next, the dry film and the dielectric green sheet are stacked in multiple layers so that they alternately overlap, and then heated and pressed to form a pressed body. This pressed body is cut, subjected to deorganic binder treatment in an oxidizing atmosphere or an inert atmosphere, and then fired, to obtain a fired chip. Next, external electrode paste is applied to both ends of the fired chip, and after firing, nickel plating or the like is applied to the surface of the external electrode to obtain a multilayer ceramic capacitor.

Conventionally, screen printing has been generally used as a printing method for printing conductive paste onto dielectric green sheets, but in response to demands for miniaturization and thinning of electronic devices and improved productivity, finer electrode patterns have been printed with high productivity. It is being asked to do so.

As one of the printing methods for conductive paste, a gravure printing method has been proposed, which is a continuous printing method in which the conductive paste is transferred from the plate by filling the concave portion formed in the plate with conductive paste and pressing it firmly against the printing surface. The gravure printing method has fast printing speed and excellent productivity. When using the gravure printing method, it is necessary to appropriately select the binder resin, dispersant, solvent, etc. in the conductive paste and adjust the properties such as viscosity to a range suitable for gravure printing.

For example, in Patent Document 1, a multilayer ceramic electronic component having a plurality of ceramic layers and an internal conductor film extending along a specific interface between the ceramic layers is used to form the internal conductor film by gravure printing. A conductive paste comprising 30 to 70% by weight of a solid component containing metal powder, 1 to 10% by weight of an ethylcellulose resin component with an ethoxy group content of 49.6% or more, 0.05 to 5% by weight of a dispersant, and the remainder as a solvent. component, the viscosity η _0.1 at a shear rate of 0.1 (s ^-1 ) is 1 Pa·s or more, and the viscosity η _0.02 at a shear rate of 0.02 (s ^-1 ) satisfies the conditions expressed by a specific formula, A conductive paste that is a thixotropic fluid is described.

Additionally, in Patent Document 2, it is a conductive paste used for forming by gravure printing in the same manner as in Patent Document 1, comprising 30 to 70% by weight of a solid component containing metal powder and 1 to 10% by weight of a resin component. A thixotropic fluid containing 0.05 to 5% by weight of a dispersant and a solvent component as the balance, and having a viscosity of 1 Pa·s or more at a shear rate ^{of 0.1 (s -1 )} . Based on the viscosity of , a conductive paste having a viscosity change rate of 50% or more at a shear rate of 10 (s ^-1 ) is described.

According to Patent Documents 1 and 2, these conductive pastes are thixotropic fluids with a viscosity of 1 Pa·s or more at a shear rate of 0.1 (s ^-1 ), and stable continuous printing properties at high speeds are obtained in gravure printing. , it is said that multilayer ceramic electronic components such as multilayer ceramic capacitors can be manufactured with good production efficiency.

Additionally, Patent Document 3 discloses a conductive paste for internal electrodes of a multilayer ceramic capacitor containing conductive powder (A), organic resin (B), organic solvent (C), additive (D), and dielectric powder (E), The organic resin (B) is composed of polyvinyl butyral with a degree of polymerization of 10,000 to 50,000, and ethylcellulose with a weight average molecular weight of 10,000 to 100,000, and the organic solvent (C) is propylene glycol monobutyl ether or propylene glycol mono. It consists of a mixed solvent of butyl ether and propylene glycol methyl ether acetate, or a mixed solvent of propylene glycol monobutyl ether and mineral spirit, the additive (D) consists of a separation inhibitor and a dispersant, and polycarboxylic acid is used as the separation inhibitor. A conductive paste for gravure printing consisting of a composition containing a boxylic acid polymer or a salt of polycarboxylic acid is described. According to Patent Document 3, this conductive paste has a viscosity suitable for gravure printing, improves uniformity and stability of the paste, and has good drying properties.

Japanese Patent Publication No. 2003-187638 Japanese Patent Publication No. 2003-242835 Japanese Patent Publication No. 2012-174797

With the recent thinning of the internal electrode layer, the conductive powder also tends to have a smaller particle size. When the particle size of the conductive powder is small, the specific surface area of the particle surface increases, so the surface activity of the conductive powder (metal powder) increases, and the dispersibility of the conductive paste may decrease, resulting in a conductive paste with higher dispersibility. is being demanded.

Additionally, when printing a conductive paste using the gravure printing method, a lower paste viscosity is required than that of the screen printing method, so it is conceivable that the conductive powder with a relatively large specific gravity may settle and the dispersibility of the paste may decrease. In addition, in the conductive pastes described in Patent Documents 1 and 2, the dispersibility of the paste is improved by removing agglomerates in the conductive paste using a filter, but a process for removing agglomerates is required, so manufacturing The process can easily become complicated.

In view of such circumstances, the purpose of the present invention is to provide a conductive paste that has a paste viscosity suitable for gravure printing and is excellent in paste dispersibility and productivity.

In the first aspect of the present invention, a conductive paste containing conductive powder, a dispersant, a binder resin, and an organic solvent, wherein the dispersant contains an alkyl phosphate compound that is an acid-based dispersant, the binder resin contains an acetal-based resin, A conductive paste is provided in which the organic solvent contains a glycol ether-based solvent.

Additionally, the acid-based dispersant is preferably an alkyl phosphate polyoxyalkylene compound.

In addition, the dispersant may further include a base-based dispersant. Additionally, the dispersant is preferably contained in a total amount of 0.2 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of the conductive powder.

The conductive powder preferably contains at least one type of metal powder selected from Ni, Pd, Pt, Au, Ag, Cu, and alloys thereof. In addition, the conductive powder preferably has an average particle diameter of 0.05 μm or more and 1.0 μm or less. Additionally, the conductive paste preferably contains ceramic powder. Additionally, the ceramic powder preferably contains perovskite type oxide. Additionally, the ceramic powder preferably has an average particle diameter of 0.01 ㎛ or more and 0.5 ㎛ or less. Additionally, the conductive paste is preferably used for internal electrodes of multilayer ceramic components. Additionally, the conductive paste preferably has a viscosity of 0.8 Pa·S or less at a shear rate of 100 sec ^-1 and a viscosity of 0.19 Pa·S or less at a shear rate of 10000 sec ^-1 .

In a second aspect of the present invention, an electronic component formed using the conductive paste is provided.

In a third aspect of the present invention, a multilayer ceramic capacitor is provided, which has at least a laminate of a dielectric layer and an internal electrode, wherein the internal electrode is formed using the conductive paste.

The conductive paste of the present invention has a viscosity suitable for gravure printing and is excellent in dispersibility and productivity. In addition, the electrode pattern of an electronic component such as a multilayer ceramic capacitor formed using the conductive paste of the present invention has excellent printability and a uniform thickness even when forming a thin electrode.

1 is a perspective view and a cross-sectional view showing a multilayer ceramic capacitor according to an embodiment.

[Conductive paste]

The conductive paste of this embodiment contains conductive powder, a dispersant, a binder resin, and an organic solvent. Hereinafter, each component will be described in detail.

(Conductive powder)

The conductive powder is not particularly limited, and for example, one or more types of powder selected from Ni, Pd, Pt, Au, Ag, Cu, and alloys thereof can be used. Among these, Ni or its alloy powder is preferable from the viewpoints of conductivity, corrosion resistance, and cost. As the Ni alloy, for example, an alloy of Ni and at least one element selected from the group consisting of Mn, Cr, Co, Al, Fe, Cu, Zn, Ag, Au, Pt, and Pd can be used. The Ni content in the Ni alloy is, for example, 50 mass% or more, preferably 80 mass% or more. Additionally, the Ni powder may contain about several hundred ppm of S in order to suppress rapid gas generation due to partial thermal decomposition of the binder resin during binder removal treatment.

The average particle diameter of the conductive powder is preferably 0.05 μm or more and 1.0 μm or less, and more preferably 0.1 μm or more and 0.5 μm or less. When the average particle diameter of the conductive powder is within the above range, it can be preferably used as a paste for internal electrodes of a thin multilayer ceramic capacitor, and for example, the smoothness of the dried film and the density of the dried film are improved. In this specification, unless otherwise specified, the average particle size of the conductive powder is the particle size calculated from the specific surface area obtained based on the BET method. For example, the formula for calculating the average particle size of nickel powder is as follows.

Average particle size = 6/S.A × ρ···(Formula)

(ρ = 8.9 (true density of nickel), S.A = BET specific surface area of nickel powder)

The content of the conductive powder is preferably 30% by mass or more and 70% by mass or less, and more preferably 40% by mass or more and 65% by mass or less, based on the total amount of the conductive paste. When the content of the conductive powder is within the above range, conductivity and dispersibility are excellent.

(ceramic powder)

The conductive paste may contain ceramic powder. The ceramic powder is not particularly limited. For example, in the case of a paste for internal electrodes of a multilayer ceramic capacitor, a known ceramic powder is appropriately selected depending on the type of multilayer ceramic capacitor to be applied. Ceramic powders include, for example, perovskite-type oxides containing Ba and Ti, and are preferably barium titanate (BaTiO ₃ ). Additionally, one type of ceramic powder may be used, or two or more types may be used.

As the ceramic powder, a ceramic powder containing barium titanate as a main component and an oxide as a secondary component may be used. Examples of the oxide include one or more oxides selected from Mn, Cr, Si, Ca, Ba, Mg, V, W, Ta, Nb, and rare earth elements.

In addition, the ceramic powder includes, for example, a perovskite-type oxide ferroelectric ceramic powder in which Ba atoms or Ti atoms of barium titanate (BaTiO ₃ ) are replaced with other atoms, such as Sn, Pb, Zr, etc. You may hear it.

As the ceramic powder in the internal electrode paste, a powder of the same composition as the dielectric ceramic powder constituting the dielectric green sheet of the multilayer ceramic capacitor may be used. As a result, the occurrence of cracks due to mismatch in shrinkage at the interface between the dielectric layer and the internal electrode layer during the sintering process is suppressed. Such ceramic powders include, in addition to the perovskite-type oxides containing Ba and Ti, for example, ZnO, ferrite, PZT, BaO, Al ₂ O ₃ , Bi ₂ O ₃ , and R (rare earth element) ₂ Oxides such as O ₃ , TiO ₂ , and Nd ₂ O ₃ may be mentioned.

The average particle diameter of the ceramic powder is, for example, 0.01 μm or more and 0.5 μm or less, and preferably 0.01 μm or more and 0.3 μm or less. When the average particle size of the ceramic powder is within the above range, when used as an internal electrode paste, a sufficiently thin and uniform internal electrode can be formed. The average particle size of the ceramic powder is the particle size calculated from the specific surface area obtained based on the BET method, similar to the conductive powder described above.

The content of the ceramic powder is preferably 1 part by mass or more and 30 parts by mass or less, and more preferably 3 parts by mass or more and 30 parts by mass or less, based on 100 parts by mass of the conductive powder.

The content of the ceramic powder is preferably 1 mass% or more and 20 mass% or less, and more preferably 3 mass% or more and 20 mass% or less, based on the total amount of the conductive paste.

(Binder Resin)

Binder resin contains acetal-based resin. As the acetal-based resin, butyral-based resins such as polyvinyl butyral are preferable. When the binder resin contains an acetal-based resin, the viscosity can be adjusted to be suitable for gravure printing, and the adhesive strength with the green sheet can be further improved. For example, the binder resin may contain 20% by mass or more of acetal-based resin, may contain 30% by mass or more, may contain 60% by mass or more of the entire binder resin, or may be composed only of acetal-based resin.

The content of the acetal-based resin is preferably 1 part by mass or more and 10 parts by mass or less, and more preferably 1 part by mass or more and 8 parts by mass or less, based on 100 parts by mass of the conductive powder.

In addition, the binder resin may contain other resins other than acetal-based resin. The other resin is not particularly limited, and known resins can be used. Other resins include, for example, cellulose-based resins such as methylcellulose, ethylcellulose, ethylhydroxyethylcellulose, and nitrocellulose, and acrylic-based resins. Among these, from the viewpoint of solubility in solvents and combustion decomposability, etc. , ethylcellulose is preferred. In addition, the molecular weight of the binder resin is, for example, about 20,000 to 200,000.

The content of the binder resin is preferably 1 part by mass or more and 10 parts by mass or less, and more preferably 1 part by mass or more and 8 parts by mass or less, based on 100 parts by mass of the conductive powder.

The content of the binder resin is preferably 0.5 mass% or more and 10 mass% or less, and more preferably 0.5 mass% or more and 6 mass% or less, relative to the entire conductive paste. When the binder resin content is within the above range, conductivity and dispersibility are excellent.

(organic solvent)

The organic solvent includes at least one of a glycol ether-based solvent and an acetate-based solvent, and preferably includes a glycol ether-based solvent.

Glycol ether-based solvents include, for example, (di)ethylene such as diethylene glycol mono-2-ethylhexyl ether, ethylene glycol mono-2-ethylhexyl ether, diethylene glycol monohexyl ether, and ethylene glycol monohexyl ether. Glycol ethers and propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, and propylene glycol monobutyl ether (PNB). Among them, propylene glycol monoalkyl ethers are preferable, and propylene glycol monobutyl ether is more preferable. When the organic solvent contains a glycol ether-based solvent, it has excellent compatibility with the above-mentioned binder resin and also has excellent drying properties.

The organic solvent may contain, for example, 25% by mass or more of the glycol ether-based solvent, 50% by mass or more of the entire organic solvent, or may be composed only of the glycol ether-based solvent. In addition, the glycol ether-based solvent may be used individually by 1 type, or may be used in combination of 2 or more types.

Acetate-based solvents include, for example, dihydroterphinyl acetate, isobornyl acetate, isobornyl propionate, isobornyl butyrate, isobornyl isobutyrate, ethylene glycol monobutyl ether acetate, and dipropylene glycol. and glycol ether acetates such as methyl ether acetate, 3-methoxy-3-methylbutyl acetate, and 1-methoxypropyl-2-acetate.

When the organic solvent contains an acetate-based solvent, for example, at least one selected from dihydroterphinyl acetate, isobornyl acetate, isobornyl propionate, isobornyl butyrate, and isobornyl isobutyrate. An acetate-based solvent (A) may be included. Among these, isobornyl acetate is more preferable. The acetate-based solvent is preferably contained in an amount of 90% by mass or more and 100% by mass or less, more preferably 100% by mass, relative to the total organic solvents excluding the glycol ether-based solvent.

In addition, when the organic solvent contains an acetate-based solvent, for example, the acetate-based solvent (A) described above and at least one acetate-based solvent selected from ethylene glycol monobutyl ether acetate and dipropylene glycol methyl ether acetate. (B) may be included. When using such a mixed solvent, the viscosity of the conductive paste can be easily adjusted, and the drying speed of the conductive paste can be increased.

In the case of a mixed liquid containing the acetate-based solvent (A) and the acetate-based solvent (B), the acetate-based solvent (A) is preferably contained in an amount of 50% by mass or more and 90% by mass or less relative to the entire acetate-based solvent, and is more preferred. It contains 60% by mass or more and 80% by mass or less. In the case of the above liquid mixture, it contains 10% by mass or more and 50% by mass or less of the acetate-based solvent (B) relative to the entire acetate-based solvent, and more preferably contains 20% by mass or more and 40% by mass or less.

Additionally, the organic solvent may include other organic solvents other than the glycol ether-based solvent and the acetate-based solvent. The other organic solvent is not particularly limited, and any known organic solvent capable of dissolving the binder resin can be used. Other organic solvents include, for example, acetic acid ester-based solvents such as ethyl acetate, propyl acetate, isobutyl acetate, and butyl acetate, ketone-based solvents such as methyl ethyl ketone and methyl isobutyl ketone, terpineol, and dihydroter. Terpene-based solvents such as pineol, aliphatic hydrocarbon solvents such as tridecane, nonane, and cyclohexane, etc. are included. Among these, aliphatic hydrocarbon solvents are preferable, and among aliphatic hydrocarbon solvents, mineral spirits are more preferable. In addition, one type of other organic solvents may be used, and two or more types may be used.

The organic solvent may include, for example, a glycol ether-based solvent as a main solvent and an aliphatic hydrocarbon solvent as a secondary solvent. In this case, the glycol ether-based solvent is preferably contained in an amount of 30 to 50 parts by mass, more preferably 40 to 50 parts by mass, based on 100 parts by mass of the conductive powder, and the aliphatic hydrocarbon solvent is: For 100 parts by mass of the conductive powder, for example, it contains 15 parts by mass or more and 80 parts by mass or less, preferably 20 parts by mass or more and 80 parts by mass or less, more preferably 20 parts by mass or more and 40 parts by mass or less.

The content of the organic solvent is preferably 50 parts by mass or more and 130 parts by mass or less, and more preferably 60 parts by mass or more and 90 parts by mass or less, based on 100 parts by mass of the conductive powder. When the content of the organic solvent is within the above range, conductivity and dispersibility are excellent.

The content of the organic solvent is preferably 20% by mass or more and 50% by mass or less, and more preferably 25% by mass or more and 45% by mass or less, relative to the total amount of the conductive paste. When the content of the organic solvent is within the above range, conductivity and dispersibility are excellent.

(Dispersant)

It is preferable that the conductive paste of this embodiment contains an acid-based dispersant containing phosphorus as an acid-based dispersant, especially a phosphoric acid alkyl ester compound. As a result of examining various dispersants for use in conductive pastes, the present inventors found that by using a dispersant containing an alkyl phosphate compound together with the binder resin and organic solvent described above, the reason for this is unknown, but internal It was found that when an electrode was formed, the generation of lumps was greatly suppressed and the dispersibility of the paste was improved.

The phosphoric acid alkyl ester compound is a phosphoric acid ester having an alkyl group. Additionally, the alkyl phosphate ester compound preferably has a polyoxyalkylene structure, and is preferably an alkyl phosphate polyoxyalkylene compound.

In addition, the phosphoric acid alkyl ester compound may be a dispersant with a linear structure or a dispersant with a complex branched structure (for example, two or more branched chains), but it is preferable that it has a linear structure.

The phosphoric acid alkyl ester compound preferably includes, for example, a compound represented by the following general formula (1).

[Formula 1]

In _the general formula ( _{1 )} ,

By using a phosphoric acid alkyl ester compound as a dispersant containing phosphorus, although the details are unknown, the phosphoric acid moiety is adsorbed to the surface of the conductive powder, etc., neutralizing the surface potential or inactivating the hydrogen bonding moiety, and furthermore, other than phosphoric acid, It is presumed that the specific three-dimensional structure containing the alkyl group at the site effectively suppresses agglomeration of conductive powder and the like, and can further improve the stability of the paste viscosity.

Additionally, the acid-based dispersant containing phosphorus may be a mixture of an alkyl phosphoric acid ester compound and another phosphoric acid-based dispersant, but is preferably made of an alkyl phosphoric acid ester compound, and is more preferably made of an alkyl phosphoric acid polyoxyalkylene compound. Additionally, the acid-based dispersant containing phosphorus may be a mixture, but is preferably a single compound.

The acid-based dispersant containing phosphorus may be contained, for example, from 0.2 parts by mass to 2 parts by mass, and preferably from 0.2 parts by mass to 1 part by mass, with respect to 100 parts by mass of the conductive powder. When the content of the acid-based dispersant containing phosphorus is within the above range, the dispersibility of the conductive powder in the conductive paste is excellent.

The acid-based dispersant containing phosphorus is contained, for example, at 3 mass% or less with respect to the entire conductive paste. The upper limit of the content of the acid-based dispersant containing phosphorus is preferably 2 mass% or less, more preferably 1.5 mass% or less, and still more preferably 1 mass% or less. The lower limit of the content of the acid-based dispersant containing the above phosphorus is not particularly limited, but is, for example, 0.1% by mass or more.

Acid-based dispersants containing phosphorus, such as phosphoric acid alkyl ester compounds, can be used, for example, by selecting those that satisfy the above characteristics from commercially available products. In addition, the above dispersant may be manufactured so as to satisfy the above characteristics using a conventionally known production method.

As a dispersant, the conductive paste may use only the acid-based dispersant containing the above-described phosphoric acid, or may use an acid-based dispersant other than the acid-based dispersant containing phosphorus. Other acid-based dispersants include, for example, higher fatty acids and polymer surfactants. These dispersants may be used singly or in combination of two or more types.

The higher fatty acids may be unsaturated carboxylic acids or saturated carboxylic acids, and are not particularly limited, but include stearic acid, oleic acid, behenic acid, myristic acid, palmitic acid, linoleic acid, lauric acid, linolenic acid, etc. with 11 carbon atoms. The above can be mentioned. Among them, oleic acid or stearic acid is preferable.

Other acid-based dispersants are not particularly limited and include alkylmonoamine salt types represented by monoalkylamine salts, alkyldiamine salt types represented by N-alkyl (C14 to C18) propylenediamine dioleate, and alkyltrimethylammonium chloride. Representative alkyltrimethylammonium salt type, alkyldimethylbenzylammonium salt type represented by coconut alkyldimethylbenzylammonium chloride, quaternary ammonium salt type represented by alkyl·dipolyoxyethylenemethylammonium chloride, alkylpyridinium salt type, and dimethylstearylamine. tertiary amine type, polyoxyethylene alkylamine type represented by polyoxypropylene and polyoxyethylene alkylamine, N,N',N'-tris(2-hydroxyethyl)-N-alkyl (C14 to 18) Examples include surfactants selected from oxyethylene addition forms of diamines, such as 1,3-diaminopropane.

Additionally, the dispersant may contain a dispersant other than an acid-based dispersant. Dispersants other than acid-based dispersants include base-based dispersants, nonionic dispersants, and amphoteric dispersants. These dispersants may be used singly or in combination of two or more types.

Examples of the base-based dispersant include aliphatic amines such as laurylamine, polyethylene glycolaurylamine, rosinamine, cetylamine, myristylamine, and stearylamine. When the conductive paste further contains a base-based dispersant in addition to the acid-based dispersant containing phosphorus, it is possible to achieve both viscosity stability over time and paste dispersibility at a very high level.

The base-based dispersant may be contained, for example, in an amount of 0.01 parts by mass or more and less than 2 parts by mass, preferably 0.01 parts by mass or more and 1 part by mass or less, more preferably 0.02 parts by mass or more. It contains not more than parts by mass, more preferably not less than 0.02 parts by mass and not more than 0.5 parts by mass. In addition, the base-based dispersant may be contained, for example, in an amount of 10 to 300 parts by mass, preferably 50 to 150 parts by mass, based on 100 parts by mass of the acid-based dispersant. When the base-based dispersant is contained within the above range, the paste has better viscosity stability over time.

The base-based dispersant is contained, for example, in an amount of 0 mass% or more and 2.5 mass% or less, preferably 0 mass% or more and 1.5 mass% or less, more preferably 0 mass%, relative to the entire conductive paste. It contains % or more and 1.0 mass% or less, more preferably 0.1 mass% or more and 1.0 mass% or less, and more preferably contains 0.1 mass% or more and 0.8 mass% or less. When the base-based dispersant is contained within the above range, the paste has better viscosity stability over time.

In the conductive paste, the content of the entire dispersant (including the acid-based dispersant containing phosphorus and any other dispersants) is, for example, 0.2 parts by mass or more and 2 parts by mass based on 100 parts by mass of the conductive powder. It may be less than or equal to 0.2 parts by mass and less than or equal to 1 part by mass. If the content of the dispersant (total) exceeds the above range, the drying properties of the conductive paste may worsen, sheet attack may occur, or the green sheet may become unable to be peeled from the base PET film.

(Other ingredients)

The conductive paste of this embodiment may, if necessary, contain other components other than the components mentioned above. As other ingredients, conventionally known additives such as antifoaming agents, plasticizers, surfactants, and thickeners can be used.

(Conductive paste)

The method for producing the conductive paste of this embodiment is not particularly limited, and conventionally known methods can be used. The conductive paste can be produced, for example, by stirring and kneading each of the above components using a three-roll mill, ball mill, mixer, etc. At that time, if a dispersant is applied to the surface of the conductive powder in advance, the conductive powder is sufficiently loosened without agglomerating and the dispersant spreads widely on the surface, making it easy to obtain a uniform conductive paste. Additionally, the binder resin is dissolved in a part of the organic solvent in advance to produce an organic vehicle, and then the conductive powder, ceramic powder, dispersant, and organic vehicle are added to the organic solvent for paste adjustment, and then stirred and kneaded. , you may produce a conductive paste.

The conductive paste preferably has a viscosity of 0.8 Pa·S or less at a shear rate of 100 sec ^-1 . When the viscosity at a shear rate of 100 sec ^-1 is within the above range, it can be suitably used as a conductive paste for gravure printing. If the above range is exceeded, the viscosity may be too high and may not be suitable for gravure printing. The lower limit of the viscosity at a shear rate of 100 sec ^-1 is not particularly limited, but is, for example, 0.2 Pa·S or more.

Additionally, the viscosity of the conductive paste at a shear rate of 10000 sec ^-1 is preferably 0.19 Pa·S or less, and more preferably 0.18 Pa·S or less. When the viscosity at a shear rate of 10000 sec ^-1 is within the above range, it can be suitably used as a conductive paste for gravure printing. Even when it exceeds the above range, the viscosity may be too high and it may not be suitable for gravure printing. The lower limit of the viscosity at a shear rate of 10000 sec ^-1 is not particularly limited, but is, for example, 0.05 Pa·S or more.

Conductive paste can be suitably used in electronic components such as multilayer ceramic capacitors. A multilayer ceramic capacitor has a dielectric layer formed using a dielectric green sheet and an internal electrode layer formed using a conductive paste.

In the multilayer ceramic capacitor, it is preferable that the dielectric ceramic powder contained in the dielectric green sheet and the ceramic powder contained in the conductive paste are powders of the same composition. In the multilayer ceramic device manufactured using the conductive paste of this embodiment, sheet attack and peeling defects of the dielectric green sheet are suppressed even when the thickness of the dielectric green sheet is, for example, 3 μm or less.

[Electronic parts]

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of the electronic component etc. of this invention will be described with reference to the drawings. In drawings, there are cases where the drawings are appropriately expressed schematically or by changing the scale. Additionally, the positions and directions of members will be explained with reference to the XYZ orthogonal coordinate system shown in Figure 1, etc., as appropriate. In this XYZ orthogonal coordinate system, the X and Y directions are horizontal directions, and the Z direction is a vertical direction (up and down direction).

1A and 1B are diagrams showing a multilayer ceramic capacitor 1, which is an example of an electronic component according to the embodiment. The multilayer ceramic capacitor (1) includes a ceramic laminate (10) in which dielectric layers (12) and internal electrode layers (11) are alternately stacked, and external electrodes (20).

Hereinafter, a method for manufacturing a multilayer ceramic capacitor using the conductive paste will be described. First, a conductive paste is formed on a dielectric green sheet by a printing method, and a dry film is formed. A plurality of dielectric green sheets having this dried film on the upper surface are stacked by pressing and then fired to integrate, thereby producing a multilayer ceramic sintered body (ceramic laminate 10) that becomes the ceramic capacitor body. Thereafter, the multilayer ceramic capacitor 1 is manufactured by forming a pair of external electrodes at both ends of the ceramic multilayer body 10. Below, it is explained in more detail.

First, prepare a dielectric green sheet, which is an unfired ceramic sheet. For this dielectric green sheet, for example, a dielectric layer paste obtained by adding an organic binder such as polyvinyl butyral and a solvent such as terpineol to a predetermined ceramic powder such as barium titanate is used as a support film such as PET film. Examples include those that are applied in a sheet form, dried, and the solvent is removed. Additionally, the thickness of the dielectric layer made of the dielectric green sheet is not particularly limited, but is preferably 0.05 μm or more and 3 μm or less from the viewpoint of the request for miniaturization of the multilayer ceramic capacitor.

Next, the above-described conductive paste is printed and applied to one side of this dielectric green sheet using a gravure printing method to form the internal electrode layer 11 made of the conductive paste, and a plurality of sheets are prepared. In addition, the thickness of the internal electrode layer 11 made of the conductive paste is preferably 1 μm or less after drying from the viewpoint of the request for thinning the internal electrode layer 11.

Next, the dielectric green sheet is peeled from the support film, and the dielectric green sheet and the conductive paste (dry film) formed on one side of the dielectric green sheet are stacked alternately, and then subjected to heat and pressure treatment to form a laminate (pressed body). get Additionally, a configuration may be used in which protective dielectric green sheets to which no conductive paste is applied are additionally disposed on both sides of the laminate (pressed body).

Next, the laminate is cut to a predetermined size to form a green chip, and then the green chip is subjected to a binder removal treatment and fired in a reducing atmosphere to produce a multilayer ceramic sintered body (ceramic laminate 10). . In addition, the atmosphere in the binder removal treatment is preferably an atmosphere or an N ₂ gas atmosphere. The temperature when performing the binder removal treatment is, for example, 200°C or more and 400°C or less. In addition, it is preferable that the holding time of the above temperature when performing the binder removal treatment is 0.5 hours or more and 24 hours or less. In addition, the firing is carried out in a reducing atmosphere to suppress oxidation of the metal used in the internal electrode layer, and the temperature when firing the laminate is, for example, 1000°C or more and 1350°C or less, and the firing The temperature holding time when carrying out is, for example, 0.5 hours or more and 8 hours or less.

By firing the green chip, the organic binder in the green sheet is completely removed, and the ceramic raw material powder is fired, thereby forming the ceramic dielectric layer 12. In addition, the organic vehicle in the internal electrode layer 11 is removed, and the nickel powder or alloy powder mainly containing nickel is sintered or melted and integrated to form an internal electrode, and the dielectric layer 12 and the internal electrode layer 11 are formed in plurality. A ceramic laminate 10 in which long, alternating layers are laminated is formed. Additionally, from the viewpoint of increasing reliability by inserting oxygen into the inside of the dielectric layer and suppressing re-oxidation of the internal electrodes, the ceramic laminate 10 after firing may be annealed.

Then, the multilayer ceramic capacitor 1 is manufactured by forming a pair of external electrodes 20 on the produced ceramic multilayer body 10. For example, the external electrode 20 includes an external electrode layer 21 and a plating layer 22. The external electrode layer 21 is electrically connected to the internal electrode layer 11. Additionally, as a material for the external electrode 20, for example, copper, nickel, or an alloy thereof can be preferably used. Additionally, electronic components other than multilayer ceramic capacitors may be used.

Example

Hereinafter, the present invention will be described in detail based on Examples and Comparative Examples, but the present invention is not limited at all by the Examples.

[Assessment Methods]

(Viscosity of conductive paste)

The viscosity after production of the conductive paste was measured using a rheometer under the conditions of a shear rate of 100 sec ^-1 and 10000 sec ^-1 .

(Dispersibility of conductive paste)

The dispersibility of the conductive paste was evaluated by the following method.

On a glass substrate (2 inch), a sample (produced conductive paste) is printed (GAP thickness = 5 μm) and dried. Drying was performed in an air atmosphere at a maximum temperature of 120 to 150°C in a belt furnace. The dried film (2 cm (Backlight = light is emitted from the back of the glass substrate) and the presence or absence of lumps was confirmed. When no lumps were observed, the dispersibility of the conductive paste was evaluated as "good", and when one or more lumps were observed, the dispersibility of the conductive paste was evaluated as "poor."

[Materials used]

(Conductive powder)

As the conductive powder, Ni powder (average particle diameter: 0.3 μm) was used.

(ceramic powder)

As the ceramic powder, barium titanate (BaTiO ₃ ; average particle diameter 0.06 μm) was used.

(Binder Resin)

As the binder resin, polyvinyl butyral resin (PVB, acetal-based resin) and ethylcellulose (EC) were used.

(Dispersant)

(1) As the acid-based dispersant (A), an alkylpolyoxyalkylene phosphate compound was used.

(2) As a base-based dispersant, rosinamine (B), polyethylene glycolaurylamine (C), and oleylamine (D) were used.

(3) As an acid-based dispersant (for comparative example) other than the acid-based dispersant (A) described above, a phosphoric acid-based dispersant (E) containing phosphoric acid polyester (polyester having a phosphoric acid group) as a main component and the balance being phosphoric acid was used.

(organic solvent)

As organic solvents, propylene glycol monobutyl ether (PNB, glycol ether-based solvent), mineral spirit (MA), and terpineol (TPO) were used.

[Example 1]

For 100 parts by mass of Ni powder, which is a conductive powder, 25 parts by mass of ceramic powder, 0.28 parts by mass of acid-based dispersant (A) as a dispersant, 4 parts by mass of EC as a binder resin, 2 parts by mass of PVB, and PNB as an organic solvent. A conductive paste was produced by mixing 48 parts by mass and 21 parts by mass of MA. The viscosity and dispersibility of the produced conductive paste were evaluated by the above method. Table 1 shows the content of the dispersant and the like in the conductive paste, and Table 2 shows the evaluation results of the viscosity and dispersibility of the conductive paste.

[Example 2]

A conductive paste was produced and evaluated in the same manner as in Example 1, except that 0.5 parts by mass of the acid-based dispersant (A) was used as the dispersant. Table 1 shows the content of the dispersant and the like in the conductive paste, and Table 2 shows the evaluation results of the viscosity and dispersibility of the conductive paste.

[Example 3]

A conductive paste was produced and evaluated in the same manner as in Example 1, except that 1.0 parts by mass of the acid-based dispersant (A) was used as the dispersant. Table 1 shows the content of the dispersant and the like in the conductive paste, and Table 2 shows the evaluation results of the viscosity and dispersibility of the conductive paste.

[Example 4]

A conductive paste was produced and evaluated in the same manner as in Example 1, except that 0.28 parts by mass of an acid-based dispersant (A) and 0.10 parts by mass of rosinamine (B) were mixed as a dispersant. Table 1 shows the content of the dispersant and the like in the conductive paste, and Table 2 shows the evaluation results of the viscosity and dispersibility of the conductive paste.

[Example 5]

A conductive paste was produced and evaluated in the same manner as in Example 1, except that 0.28 parts by mass of an acid-based dispersant (A) and 0.10 parts by mass of polyethylene glycolaurylamine (C) were mixed as a dispersant. Table 1 shows the content of the dispersant and the like in the conductive paste, and Table 2 shows the evaluation results of the viscosity and dispersibility of the conductive paste.

[Example 6]

A conductive paste was produced and evaluated in the same manner as in Example 1, except that 0.28 parts by mass of an acid-based dispersant (A) and 0.10 parts by mass of oleylamine (D) were mixed as a dispersant. Table 1 shows the content of the dispersant and the like in the conductive paste, and Table 2 shows the evaluation results of the viscosity and dispersibility of the conductive paste.

[Example 7]

A conductive paste was produced and evaluated in the same manner as in Example 1, except that 0.28 parts by mass of an acid-based dispersant (A) and 0.22 parts by mass of oleylamine (D) were mixed as a dispersant. Table 1 shows the content of the dispersant and the like in the conductive paste, and Table 2 shows the evaluation results of the viscosity and dispersibility of the conductive paste.

[Example 8]

A conductive paste was produced and evaluated in the same manner as in Example 1, except that 0.56 parts by mass of the acid-based dispersant (A) and 0.44 parts by mass of oleylamine (D) were mixed as the dispersant. Table 1 shows the content of the dispersant and the like in the conductive paste, and Table 2 shows the evaluation results of the viscosity and dispersibility of the conductive paste.

[Example 9]

A conductive paste was produced and evaluated in the same manner as in Example 1, except that only 6 parts by mass of PVB was used as the binder resin. Table 1 shows the content of the dispersant and the like in the conductive paste, and Table 2 shows the evaluation results of the viscosity and dispersibility of the conductive paste.

[Example 10]

A conductive paste was produced and evaluated in the same manner as in Example 1, except that 57 parts by mass of PNB and 12 parts by mass of MA were used as organic solvents. Table 1 shows the content of the dispersant and the like in the conductive paste, and Table 2 shows the evaluation results of the viscosity and dispersibility of the conductive paste.

[Comparative Example 1]

A conductive paste was produced and evaluated in the same manner as in Example 1, except that 0.28 parts by mass of a phosphoric acid-based dispersant (E) and 0.10 parts by mass of a base-based dispersant (B) containing phosphopolyester as a main component were used as the dispersant. Table 1 shows the content of the dispersant and the like in the conductive paste, and Table 2 shows the evaluation results of the viscosity and dispersibility of the conductive paste.

[Comparative Example 2]

A conductive paste was produced and evaluated in the same manner as in Example 1, except that only terpineol (TPO) was used as the organic solvent. Table 1 shows the content of the dispersant and the like in the conductive paste, and Table 2 shows the evaluation results of the viscosity and dispersibility of the conductive paste.

[Comparative Example 3]

A conductive paste was produced and evaluated in the same manner as in Example 1, except that only EC was used as the binder resin. Table 1 shows the content of the dispersant and the like in the conductive paste, and Table 2 shows the evaluation results of the viscosity and dispersibility of the conductive paste.

[Comparative Example 4]

A conductive paste was produced and evaluated in the same manner as in Example 1, except that only EC was used as the binder resin and only terpineol was used as the organic solvent. Table 1 shows the content of the dispersant and the like in the conductive paste, and Table 2 shows the evaluation results of the viscosity and dispersibility of the conductive paste.

(Evaluation results)

The conductive paste of the example had a viscosity of 0.34 to 0.69 Pa·S at a shear rate of 100 sec ^-1 and a viscosity of 0.12 to 0.19 Pa·S at a shear rate of 10000 sec ^-1 , and had a viscosity suitable for gravure printing. Additionally, in the conductive paste of this example, no lumps were observed on the surface of the dried film after printing, showing that the paste had excellent dispersibility.

On the other hand, in the conductive paste of Comparative Example 1 using a phosphoric acid-based dispersant (E) other than the acid-based dispersant (A), lumps were observed on the surface of the dried film after printing, showing that the dispersibility of the paste was poor. In addition, in the conductive paste of Comparative Example 2 in which the organic solvent deviates from the scope of the present invention, Comparative Example 3 in which the binder resin deviates from the scope of the present invention, and Comparative Example 4 in which the organic solvent and binder resin deviate from the scope of the present invention, A viscosity suitable for gravure printing could not be obtained. Therefore, in Comparative Examples 2 to 4, an appropriate dried film could not be obtained and dispersibility could not be evaluated.

The conductive paste of the present invention has a viscosity suitable for gravure printing, and the paste has good dispersibility. Therefore, the conductive paste of the present embodiment can be particularly preferably used as a raw material for internal electrodes of multilayer ceramic capacitors, which are chip components of electronic devices such as mobile phones and digital devices, and is particularly preferably used as a conductive paste for gravure printing. You can use it.

One ; Multilayer Ceramic Condenser
10 ; ceramic laminate
11 ; inner electrode layer
12 ; dielectric layer
20 ; external electrode
21 ; outer electrode layer
22 ; plating layer

Claims (13)

A conductive paste containing conductive powder, a dispersant, a binder resin, and an organic solvent,
The dispersant includes a phosphoric acid alkyl ester compound, which is an acid-based dispersant,
The binder resin includes an acetal-based resin,
The organic solvent includes a glycol ether-based solvent,
The phosphoric acid alkyl ester compound is a compound represented by the following general formula (1):

(In _the general _formula (1 ₎ ,
Conductive paste. According to claim 1,
A conductive paste in which the dispersant further contains a base-based dispersant. According to claim 1,
A conductive paste wherein the dispersant is contained in a total amount of 0.2 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of the conductive powder. According to claim 1,
The conductive powder is a conductive paste containing at least one type of metal powder selected from Ni, Pd, Pt, Au, Ag, Cu, and alloys thereof. According to claim 1,
The conductive powder is a conductive paste having an average particle diameter of 0.05 μm or more and 1.0 μm or less. According to claim 1,
A conductive paste containing ceramic powder. According to claim 6,
A conductive paste in which the ceramic powder contains a perovskite-type oxide. According to claim 6,
The ceramic powder is a conductive paste having an average particle diameter of 0.01 ㎛ or more and 0.5 ㎛ or less. According to claim 1,
Conductive paste for internal electrodes of multilayer ceramic parts. According to claim 1,
A conductive paste having a viscosity of 0.8 Pa·S or less at a shear rate of 100 sec ^-1 and a viscosity of 0.19 Pa·S or less at a shear rate of 10000 sec ^-1 . An electronic component formed using the conductive paste according to any one of claims 1 to 10. A multilayer ceramic capacitor having at least a laminate of dielectric layers and internal electrodes,
A multilayer ceramic capacitor wherein the internal electrode is formed using the conductive paste according to any one of claims 1 to 10. delete

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