TWI798292B - Conductive paste, electronic parts and laminated ceramic capacitors - Google Patents

Abstract

The present invention provides a conductive paste having a small change in viscosity with time, excellent viscosity stability, and excellent dry film density after coating, and the like. The conductive paste of the present invention contains conductive powder, ceramic powder, dispersant, binder resin, and organic solvent. The dispersant contains 0.01 to 2 parts by mass based on 100 parts by mass of the conductive powder. The amino acid dispersant shown in chemical formula (1), and, based on 100 mass parts of conductive powder, contains the amine dispersant shown in chemical formula (2) below 0.01 mass part to 2 mass parts, with respect to The whole electroconductive paste contains 40 mass % or more and 60 mass % or less of electroconductive powder.

Description

Conductive paste, electronic parts and laminated ceramic capacitors

The present invention relates to a conductive paste, an electronic component, and a laminated ceramic capacitor.

Along with the miniaturization and high performance of electronic equipment such as mobile phones and digital devices, miniaturization and high capacity are also desired for electronic components including laminated ceramic capacitors and the like. A laminated ceramic capacitor has a structure in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately laminated. By reducing the thickness of the dielectric layers and internal electrode layers, miniaturization and high capacity can be achieved.

For example, a laminated ceramic capacitor can be manufactured in the following manner. First, on the surface of a dielectric green sheet containing a dielectric powder such as barium titanate (BaTiO ₃ ) and a binder resin, a conductive paste for internal electrodes is printed (coated) in a predetermined electrode pattern, and Drying is performed to form a dry film. Next, the dry film and the dielectric green sheet are laminated so that they are alternately stacked, and are bonded by heat and pressure to be integrated to form a pressure-bonded body. The press-bonded body is cut, subjected to an organic binder removal treatment in an oxidizing gas or an inert gas, and then fired to obtain a fired wafer. Next, a paste for external electrodes is applied to both ends of the fired wafer, and after firing, nickel plating or the like is performed on the surface of the external electrodes to obtain a laminated ceramic capacitor.

Generally, a conductive paste for forming internal electrode layers contains conductive powder, ceramic powder, binder resin, and organic solvent. Moreover, in order to improve the dispersibility of electroconductive powder etc., electroconductive paste may contain a dispersing agent. Along with the thinning of the internal electrode layer in recent years, the particle size of the conductive powder also tends to be reduced. When the particle size of the conductive powder is small, the specific surface area of the particle surface becomes large, so the surface activity of the conductive powder (metal powder) becomes high, and the dispersibility and viscosity characteristics may decrease.

Therefore, an attempt has been made to improve the temporal viscosity characteristics of the conductive paste. For example, Patent Document 1 describes a conductive paste containing at least a metal component, an oxide, a dispersant, and a binder resin. The metal component is Ni powder whose surface composition has a specific composition ratio. The acid point of the dispersant is The amount is 500~2000μmol/g, and the acid point amount of the binder resin is 15~100μmol/g. Furthermore, according to Patent Document 1, the conductive paste has good dispersibility and viscosity stability.

In addition, Patent Document 2 describes a conductive paste for internal electrodes, which is composed of a conductive powder, a resin, an organic solvent, a co-material of ceramic powder mainly composed of TiBaO ₃ , and an aggregation inhibitor, wherein the above-mentioned aggregation inhibitor The content of the agent is not less than 0.1% by weight and not more than 5% by weight, and the above-mentioned aggregation inhibitor is a tertiary or secondary amine represented by a specific structural formula. According to Patent Document 2, this conductive paste for internal electrodes suppresses aggregation of common material components, has excellent long-term storage properties, and can achieve thinner multilayer ceramic capacitors.

On the other hand, when thinning the internal electrode layer, a dry film obtained by printing and drying a conductive paste for internal electrodes on the surface of a dielectric green sheet is required to have a high density. For example, a metal ultrafine powder slurry is proposed in Patent Document 3, which contains an organic solvent, a surfactant, and a metal ultrafine particle, wherein the above-mentioned surfactant is oleoyl sarcosine, and in the above-mentioned metal ultrafine powder slurry , containing 70% by mass to 95% by mass of the above-mentioned superfine metal powder, based on 100 parts by mass of the above-mentioned superfine metal powder, containing more than 0.05 parts by mass and less than 2.0 parts by mass of the above-mentioned surfactant. According to Patent Document 3, by preventing the aggregation of ultrafine particles, a metal ultrafine powder slurry having no aggregated particles and excellent dispersibility and dry film density can be obtained.

[Prior technical literature] 【Patent Literature】

[Patent Document 1] Japanese Patent Laid-Open No. 2015-216244

[Patent Document 2] Japanese Patent Laid-Open No. 2013-149457

[Patent Document 3] Japanese Patent Laid-Open No. 2006-063441

However, along with the thinning of electrode patterns in recent years, it is required to further improve the viscosity characteristics over time and to increase the dry film density after coating.

In view of such a situation, an object of the present invention is to provide a conductive paste having a high dry film density, a very small change in viscosity over time, and excellent viscosity stability. Moreover, another object of this invention is to provide the electroconductive paste excellent in printability also when forming the thinned electrode.

The first aspect of the present invention provides a conductive paste, which contains conductive powder, ceramic powder, dispersant, binder resin and organic solvent, and in the dispersant, based on 100 parts by mass of the conductive powder, contains 0.01 More than 2 parts by mass of the amino acid-based dispersant represented by the following chemical formula (1), and the conductive powder is 100 parts by mass, containing 0.01 parts by mass or more than 2 parts by mass of the following chemical formula ( 2) The amine-based dispersant shown in 2) contains 40 mass % or more and 60 mass % or less of electroconductive powder with respect to the whole electroconductive paste.

(wherein, in formula (1), R ₁ represents a chain hydrocarbon group with 10 to 20 carbon atoms.)

(wherein, in formula (2), R ₂ represents an alkyl, alkenyl or alkynyl group with 8 to 16 carbon atoms, R ₃ represents an oxyethylene group, an oxypropylene group, or a methylene group, and R ₄ represents an oxidized Vinyl or propylene oxide, _R3 and _R4 can be the same or different. The N atom in formula (2) is not directly bonded to the O atom in _R3 and _R4 , and Y is 0~2 number, Z is a number from 1 to 2.)

Also, ideally, in the chemical formula (1), R ₁ represents a straight-chain hydrocarbon group having 10 to 20 carbon atoms. Moreover, it is preferable to contain the dispersing agent of 0.01 mass part or more and 3 mass parts or less with respect to the whole electroconductive paste. In addition, the conductive powder is preferably a metal powder containing at least one metal powder selected from the group consisting of Ni, Pd, Pt, Au, Ag, Cu, and alloys thereof. In addition, the average particle diameter of the conductive powder is preferably not less than 0.05 μm and not more than 1.0 μm. Also, the ceramic powder preferably contains a perovskite-type oxide. In addition, the average particle diameter of the ceramic powder is preferably not less than 0.01 μm and not more than 0.5 μm. In addition, the binder resin preferably contains at least one of cellulose-based resins, acrylic resins, and butyral-based resins. Moreover, the above-mentioned conductive paste is ideally used for internal electrodes of laminated ceramic parts.

A second aspect of the present invention provides an electronic component formed using the above-mentioned conductive paste.

A third aspect of the present invention provides a laminated ceramic capacitor comprising at least a laminate in which dielectric layers and internal electrodes are laminated, wherein the internal electrodes are formed using the above-mentioned conductive paste.

The viscosity of the conductive paste of the present invention changes less with time, has better viscosity stability, and has better dry film density after coating. In addition, the conductive paste of the present invention is also excellent in printability when forming thinned electrodes, and electrode patterns of electronic components such as laminated ceramic capacitors formed using this conductive paste can have highly accurate and uniform width and thickness. .

1‧‧‧Laminated Ceramic Capacitors

10‧‧‧Ceramic laminate

11‧‧‧internal electrode layer

12‧‧‧dielectric layer

20‧‧‧External electrodes

21‧‧‧External electrode layer

22‧‧‧Electroplating layer

[ Fig. 1 ] A perspective view and a cross-sectional view showing a multilayer ceramic capacitor according to an embodiment of the present invention.

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

(conductive powder)

The conductive powder is not particularly limited, and metal powder can be used. For example, one or more powders selected from the group consisting of Ni, Pd, Pt, Au, Ag, Cu, and alloys thereof can be used. Among them, powder of Ni or its alloy is preferable from the viewpoint of electrical conductivity, corrosion resistance, and cost. As the Ni alloy, for example, an alloy (Ni alloy) of at least one element selected from the group consisting of Mn, Cr, Co, Al, Fe, Cu, Zn, Ag, Au, Pt, and Pd and Ni and Ni can be used. The content of Ni in the Ni alloy is, for example, 50% by mass or more, preferably 80% by mass or more. In addition, in order to suppress violent gas generation due to partial thermal decomposition of the binder resin during the binder removal process, the Ni powder may contain S on the order of several hundred ppm.

The average particle diameter of the conductive powder is preferably from 0.05 μm to 1.0 μm, more preferably from 0.1 μm to 0.5 μm. When the average particle size of the conductive powder is within the above range, it can be suitably used as a slurry for an internal electrode of a thinned multilayer ceramic capacitor, and for example, the smoothness and dry film density of a dry film can be improved. The average particle diameter is a value obtained by observation with a scanning electron microscope (SEM), and is an average obtained by measuring the individual particle diameters of a plurality of particles from an image observed by a SEM at a magnification of 10,000 times. value.

The content of the conductive powder is preferably 30% by mass or more and less than 70% by mass, more preferably 40% by mass or more and 60% by mass or less with respect to the entire conductive paste. When the content of the conductive powder is within the above range, the conductivity and dispersibility are excellent.

(ceramic powder)

The ceramic powder is not particularly limited. For example, in the case of a paste for internal electrodes of a laminated ceramic capacitor, a known ceramic powder can be appropriately selected according to the type of laminated ceramic capacitor to be used. Examples of the ceramic powder include perovskite-type oxides containing Ba and Ti, preferably barium titanate (BaTiO ₃ ).

As the ceramic powder, a ceramic powder containing barium titanate as a main component and an oxide as a subcomponent can be used. Examples of oxides include oxides of Mn, Cr, Si, Ca, Ba, Mg, V, W, Ta, Nb, and one or more rare earth elements. Examples of such ceramic powders include perovskite-type oxide ferroelectric ceramic powders in which Ba atoms and Ti atoms of barium titanate (BaTiO ₃ ) are substituted with, for example, Sn, Pb, or Zr.

Powders having the same composition as the dielectric ceramic powders constituting the dielectric green sheets of the laminated ceramic capacitors can be used for the internal electrode paste. Accordingly, generation of cracks due to shrinkage mismatch at the interface between the dielectric layer and the internal electrode layer in the sintering process can be suppressed. Examples of such ceramic powders include ZnO, ferrite, PZT, BaO, Al ₂ O ₃ , Bi ₂ O ₃ , R (rare earth elements) ₂ O ₃ , TiO ₂ , and Nd in addition to the above. ₂ O ₃ and other oxides. In addition, one type of ceramic powder may be used, or two or more types may be used.

The average particle size of the ceramic powder is, for example, in a range of 0.01 μm to 0.5 μm, preferably in a range of 0.01 μm to 0.3 μm. When the average particle size of the ceramic powder is within the above range, when used as a slurry for internal electrodes, a sufficiently thin and uniform internal electrode can be formed. The average particle diameter is a value obtained by observation with a scanning electron microscope (SEM), and is an average value obtained by measuring individual particle diameters of a plurality of particles based on an image observed by a SEM at a magnification of 50,000 times. .

The content of the ceramic powder is preferably not less than 1 part by mass and not more than 30 parts by mass, more preferably not less than 3 parts by mass and not more than 30 parts by mass, based on 100 parts by mass of the conductive powder.

The content of the ceramic powder is preferably not less than 1% by mass and not more than 20% by mass, more preferably not less than 5% by mass and not more than 20% by mass, based on the entire conductive paste. When the content of the ceramic powder is within the above range, the conductivity and dispersibility are excellent.

(Binder resin)

The binder resin is not particularly limited, and known resins can be used. Examples of the binder resin include cellulose-based resins such as methylcellulose, ethylcellulose, ethylhydroxyethylcellulose, and nitrocellulose; acrylic resins; butyrals such as polyvinyl butyral; Department of resin, etc. Among them, ethyl cellulose is desirably contained from the viewpoint of solubility in a solvent, combustion decomposability, and the like. In addition, when used as a paste for internal electrodes, a butyral-based resin may be contained, or a butyral-based resin may be used alone, from the viewpoint of improving the adhesive strength with the dielectric green sheet. One kind of binder resin may be used, or two or more kinds may be used. As the binder resin, for example, cellulose-based resin and butyral-based resin can be used. 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 not less than 1 part by mass and not more than 10 parts by mass, more preferably not less than 1 part by mass and not more than 8 parts by mass, based on 100 parts by mass of the conductive powder.

The content of the binder resin is preferably from 0.5% by mass to 10% by mass with respect to the entire conductive paste, more preferably from 1% by mass to 6% by mass. When content of binder resin is in the said range, electroconductivity and dispersibility are excellent.

(Organic solvents)

The organic solvent is not particularly limited, and known organic solvents capable of dissolving the above-mentioned binder resin can be used. Examples of organic solvents include dihydroterpineol acetate, isobornyl acetate, isobornyl propionate, isobornyl butyrate and isobornyl isobutyrate, and ethylene glycol monobutyl ether acetate. , acetate-based solvents such as dipropylene glycol methyl ether acetate, terpine-based solvents such as terpineol and dihydroterpineol, and hydrocarbon-based solvents such as tridecane, nonane, and cyclohexane. In addition, one kind of organic solvent may be used, and two or more kinds may be used.

The content of the organic solvent is preferably not less than 40 parts by mass and not more than 100 parts by mass, more preferably not less than 65 parts by mass and not more than 95 parts by mass, based on 100 parts by mass of the conductive powder. When content of an organic solvent exists in the said range, electroconductivity and dispersibility are excellent.

The content of the organic solvent is preferably not less than 20% by mass and not more than 60% by mass, more preferably not less than 35% by mass and not more than 55% by mass with respect to the entire conductive paste. When content of an organic solvent exists in the said range, electroconductivity and dispersibility are excellent.

(Dispersant)

The conductive paste of this embodiment contains a dispersant. The dispersant contains an amino acid-based dispersant (amino acid-based surfactant) represented by chemical formula (1) and an amine-based dispersant represented by chemical formula (2). In addition, the dispersant may be composed of the amino acid-based dispersant represented by the chemical formula (1) and the amine-based dispersant represented by the chemical formula (2), or may contain dispersants other than the above.

As a result of studying various dispersants for dispersants used in conductive pastes, the inventors of the present invention found that by combining the above two dispersants, the viscosity of the conductive pastes changes less over time, and the dispersibility And it is excellent in viscosity stability, and the dry film density after coating is excellent. The details of the reason are not clear, but it is considered that the effect is due to the coordination of the amine group and carboxyl group present in the molecule of the dispersant to the metal atom of the conductive powder. In addition, although the dispersibility, viscosity stability, and dry film density can be improved even when the above two dispersants are used alone, the dispersibility, viscosity stability, and dry film density can be further improved by combining them. . Hereinafter, the dispersant used in this embodiment will be described.

The amino acid-based dispersant used in this embodiment has an N-acyl amino acid skeleton as shown in the following chemical formula (1), and has a chain hydrocarbon group with 10 to 20 carbon atoms.

(wherein, in formula (1), R ₁ represents a chain hydrocarbon group with 10 to 20 carbon atoms.)

In the above formula (1), R ₁ represents a chain hydrocarbon group having 10 to 20 carbon atoms. The number of carbon atoms of R ₁ is desirably not less than 15 and not more than 20. In addition, the chain hydrocarbon group may be a straight chain hydrocarbon group or a branched chain hydrocarbon group. Also, the chain hydrocarbon group may be an alkyl group, an alkenyl group or an alkynyl group. R ₁ is ideally a straight-chain hydrocarbon group, more preferably a straight-chain alkenyl group, and has a double bond.

Based on 100 parts by mass of the conductive powder, the conductive paste contains 0.01 to 2 parts by mass of the amino acid-based dispersant represented by the above formula (1), ideally 0.02 to 1 part by mass, It may be not less than 0.03 parts by mass and not more than 0.6 parts by mass, or may be not less than 0.1 parts by mass and not more than 0.6 parts by mass. When the amino acid-based dispersant is contained within the above range, the dry film density can be increased compared to the case where the amine-based dispersant is contained alone. Also, when increasing the amino acid-based dispersant within the above range, for example, when the amino acid-based dispersant is contained at least 0.1 parts by mass and not more than 2 parts by mass, preferably at least 0.1 parts by mass and not more than 1.5 parts by mass of amine In the case of an acid-based dispersant, the change in viscosity over time can be better suppressed. In addition, when the content of the amino acid-based dispersant exceeds 2 parts by mass, when the conductive paste is printed on the dielectric green sheet, grid marks may be generated on the printed surface, or the paste may be distorted. The viscosity is greatly reduced.

As the amino acid-based dispersant represented by the above formula (1), for example, an amino acid-based dispersant satisfying the above characteristics can be selected from commercially available products. In addition, the above-mentioned amino acid-based dispersant can also be produced using conventionally known production methods to satisfy the above-mentioned characteristics.

The above-mentioned amine-based dispersant is represented by the following chemical formula (2), is a tertiary amine or a secondary amine, and has a structure in which an amine group is bonded to one or two oxyalkylene groups.

(wherein, in formula (2), R ₂ represents an alkyl, alkenyl or alkynyl group with 8 to 16 carbon atoms, R ₃ represents an oxyethylene group, an oxypropylene group, or a methylene group, and R ₄ represents an oxidized Vinyl or propylene oxide, _R3 and _R4 can be the same or different. Also, the N atom in the formula (2) is not directly bonded to the O atom in _R3 and _R4 , and Y is 0~2 number, Z is a number from 1 to 2.)

In the above formula (2), R ₂ represents an alkyl, alkenyl or alkynyl group having 8 to 16 carbon atoms. When the number of carbon atoms of R ₂ is within the above range, the powder in the conductive paste has sufficient dispersibility, and the solubility to the solvent is excellent. In addition, R ₂ is ideally a linear hydrocarbon group.

In the above formula (2), R ₃ represents an oxyethylene group, an oxypropylene group, or a methylene group, R ₄ represents an oxyethylene group or an oxypropylene group, and R ₃ and R ₄ may be the same or different. In addition, the N atom in the formula (2) is not directly bonded to the O atom in _R3 and _R4 , Y is a number from 0 to 2, and Z is a number from 1 to 2.

For example, in the above formula (2), R ₃ is an oxyalkylene group represented by -AO-, and when Y is 1 to 2, the O atom in the oxyalkylene group at the end and (R ₃ )Y Adjacent H atoms are bonded. Also, when R ₃ is a methylene group, (R ₃ ) _Y is represented by -(CH ₂ ) _Y -, and when Y is 1 to 2, it bonds with an adjacent H element to form a methyl group (-CH ₃ ) or ethyl (-CH ₂ -CH ₃ ). Also, when R ₄ is an oxyalkylene group represented by -AO-, the O atom in the endmost oxyalkylene group is bonded to the H atom adjacent to (R ₄ ) _Z.

In the above formula (2), when Y is 0, the above-mentioned amine-based dispersant is a secondary amine having -R ₂ , one hydrogen group, and -(R ₄ ) _Z H. For example, when Y is 0 and Z is 2, the above-mentioned amine-based dispersant is composed of an alkyl group, an alkenyl group or an alkynyl group with 8 to 16 carbon atoms, a hydrogen group, an ethylene dioxide group, and a carbon dioxide group. A secondary amine composed of -(AO) ₂ H in which any one of the propenyl groups is bonded to an H element.

In addition, in the above-mentioned formula (2), when Y is 1, the above-mentioned amine-based dispersant is a tertiary amine having -R ₂ , -R ₃ H and -(R ₄ ) _Z H. Furthermore, when Y is 2, the above-mentioned amine-based dispersant has -R ₂ , as -(R ₃ ) ₂ H, an ethylene dioxide group, a propylene dioxide group, or a vinyl group bonded to an H element. Tertiary amine of -(AO) ₂ H or -C ₂ H ₅ , -(R ₄ ) _Z H.

Based on 100 parts by mass of the conductive powder, the conductive paste contains 0.01 to 2 parts by mass of the amine-based dispersant represented by the above formula (2), preferably 0.02 to 1 part by mass, more preferably 0.02 to 1 part by mass. It is desirable to contain 0.03 mass part or more and 0.6 mass part or less, and may contain 0.05 mass part or more and 0.6 mass part or less. When the above-mentioned amine-based dispersant is contained within the above-mentioned range, it is possible to suppress a change in viscosity with time and improve viscosity stability. In addition, when the content of the amine-based dispersant exceeds 2 parts by mass, when the conductive paste is printed on the dielectric green sheet, grid marks may be generated on the printed surface, or the viscosity of the paste may be increased. The magnitude is reduced.

The amine-based dispersant represented by the above-mentioned formula (2) can be selected from commercially available amine-based dispersants satisfying the above characteristics, for example. In addition, the above-mentioned amine-based dispersant can also be produced using conventionally known production methods to satisfy the above-mentioned characteristics.

Based on 100 parts by mass of the above-mentioned conductive powder, it is desirable to contain a dispersant (including the above-mentioned amino acid-based dispersant and amine-based dispersant) at 0.02 to 4 parts by mass, more preferably 0.04 to 2 parts by mass. Parts by mass or less. When the content of the dispersant is within the above range, the viscosity of the conductive paste can be adjusted to an appropriate range, and sheet erosion and peeling failure of the dielectric green sheet can be suppressed.

Moreover, it is desirable to contain 3 mass % or less of a dispersant (including the said amino acid type dispersant and an amine type dispersant) with respect to the electroconductive paste whole quantity. The upper limit of the content of the dispersant is preferably 2.4% by mass or less, more preferably 2% by mass or less, and still more preferably 1% by mass or less. The lower limit of the content of the dispersant is not particularly limited, and is, for example, 0.01% by mass or more, preferably 0.05% by mass or more. When the content of the dispersant is within the above range, the viscosity of the conductive paste can be adjusted to an appropriate range, and sheet erosion and peeling failure of the dielectric green sheet can be suppressed.

In addition, the conductive paste may contain dispersants other than the above-mentioned amino acid-based dispersant and amine-based dispersant within the range that does not inhibit the effect of the present invention. As dispersants other than the above, for example, acid-based dispersants including higher fatty acids, polymer surfactants, cationic dispersants other than acid-based dispersants, nonionic dispersants, amphoteric surfactants, and polymer surfactants may be included. Department of dispersants, etc. In addition, the above-mentioned dispersants may be used alone or in combination of two or more.

(conductive paste)

The method for producing the conductive paste of this embodiment is not particularly limited, and a conventionally known method can be used. For example, the conductive paste of this embodiment can be manufactured by preparing each of the above-mentioned components and stirring and kneading each component with a three-roll mill, a ball mill, a mixer, or the like. At this time, if the dispersant is applied on the surface of the conductive powder in advance, the conductive powder can be sufficiently dispersed without agglomeration, and the dispersant spreads all over the surface, making it easy to obtain a uniform conductive paste. Alternatively, the binder resin may be dissolved in an organic solvent for an organic vehicle, and after preparing the organic vehicle, conductive powder, ceramic powder, organic vehicle, and dispersant may be added to the organic solvent for slurry, followed by stirring, kneading to prepare a conductive paste.

Moreover, among the organic solvents, as the organic solvent for the carrier, it is desirable to use the same organic solvent as the organic solvent for the paste for adjusting the viscosity of the conductive paste in order to improve the affinity of the organic vehicle. The content of the organic solvent for the carrier is, for example, 5 parts by mass or more and 80 parts by mass or less based on 100 parts by mass of the conductive powder. Moreover, content of the organic solvent for carriers is desirably 10 mass % or more and 40 mass % or less with respect to the whole quantity of electroconductive paste.

When the viscosity after 24 hours from the production of the conductive paste is used as the reference (0%), the viscosity of the conductive paste after standing still for 28 days from the reference date is preferably within ±30%, more preferably within ±25%. In addition, the viscosity of the above-mentioned conductive paste can be determined by, for example, the method described in the examples (the method of measuring at 10 rpm (shear rate = 4 sec ^-1 ) using a B-type viscometer manufactured by Brookfield Co., Ltd.) and the like. To measure.

In addition, the density (DFD) of the dried film formed by printing the conductive paste is preferably more than 5.5 g/cm ³ , more preferably 5.6 g/cm ³ or more, still more preferably more than 5.6 g/cm ³ . Moreover, according to the electroconductive paste of this embodiment, the film more excellent in printability can be formed easily. For example, as described in the Examples, it is possible to suppress blurring and bleeding of the conductive paste during film production.

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

For a laminated ceramic capacitor, it is desirable that the dielectric ceramic powder contained in the dielectric green sheet and the ceramic powder contained in the conductive paste have the same composition. The multilayer ceramic capacitor produced using the conductive paste of this embodiment can suppress sheet erosion and green sheet peeling defects even when the thickness of the green sheet is, for example, 3 μm or less.

[electronic parts]

Hereinafter, embodiments of electronic components and the like according to the present invention will be described with reference to the drawings. In the drawings, it may be shown schematically or with a scale changed as appropriate. In addition, the position, direction, etc. of a component are demonstrated referring suitably the XYZ rectangular coordinate system shown in FIG. 1 etc. FIG. In this XYZ rectangular coordinate system, the X direction and the Y direction are horizontal directions, and the Z direction is a vertical direction (vertical direction).

A in FIG. 1 and B in FIG. 1 are diagrams showing a laminated ceramic capacitor 1 as an example of an electronic component of an embodiment. The laminated ceramic capacitor 1 has a laminate 10 in which dielectric layers 12 and internal electrode layers 11 are alternately laminated, and external electrodes 20 .

Hereinafter, a method of manufacturing a laminated ceramic capacitor using the above-mentioned conductive paste will be described. First, a conductive paste is printed and dried on a dielectric layer made of a dielectric green sheet to form a dry film. A plurality of dielectric layers having the dry film on the upper surface are laminated by pressure bonding, and then fired to integrate them, thereby preparing internal electrode layers 11 and dielectric layers 12 which are alternately laminated. The ceramic laminate 10 (laminate 10). Thereafter, the laminated ceramic capacitor 1 is produced by forming a pair of external electrodes 20 at both ends of the ceramic laminate 10 . Hereinafter, a more detailed description will be given.

First, a green sheet as an unfired ceramic sheet is prepared. As the green sheet, for example, a slurry for a dielectric layer obtained by adding an organic binder such as polyvinyl butyral and a solvent such as terpineol to a predetermined ceramic raw material powder such as barium titanate is exemplified. A green sheet or the like formed by coating a support film such as a PET film in a sheet shape and drying to remove the solvent. In addition, the thickness of the dielectric layer made of the green sheet is not particularly limited, but is preferably 0.05 μm or more and 3 μm or less in view of the demand for miniaturization of laminated ceramic capacitors.

Next, a plurality of sheets having dried films formed by printing (coating) the above-mentioned conductive paste on one surface of the green sheet by a known method such as screen printing and drying are prepared. In addition, the thickness of the conductive paste (dried film) after printing is desirably 1 μm or less after drying from the viewpoint of the requirement for thinning the internal electrode layer 11 .

Next, after peeling the green sheet from the support film, and laminating in a state where the dielectric layer composed of the green sheet and the dry film formed on one surface of the dielectric layer are alternately arranged, the A laminate (press-bonded body) is obtained by heating and pressurizing. Moreover, the structure which arrange|positions the green sheet for protection which does not apply|coat the electroconductive paste further on both surfaces of a laminated body (press-bonded body) is also possible.

Next, after cutting the laminated body (press-bonded body) into a predetermined size to form a green wafer, the green wafer is subjected to a binder removal process and fired under a reducing gas to prepare a ceramic laminated body 10. . In addition, the gas in the binder removal process is ideally the atmosphere or N ₂ gas atmosphere. The temperature at the time of performing binder removal process is 200 to 400 degreeC, for example. In addition, the retention time at the above-mentioned temperature when performing the binder removal treatment is preferably not less than 0.5 hours and not more than 24 hours. In addition, in order to suppress the oxidation of the metal used in the internal electrode layer, the firing is performed in a reducing gas atmosphere, and the temperature when firing the laminate (pressed body) is, for example, 1000°C to 1350°C. The temperature retention time at the time of firing is, for example, not less than 0.5 hours and not more than 8 hours.

By firing the green wafer, the organic binder in the green sheet is completely removed, and the ceramic raw material powder is fired to form the ceramic dielectric layer 12 . In addition, the organic vehicle in the dry film is removed, and the nickel powder or the alloy powder mainly composed of nickel is sintered or melted to form an internal electrode, and further, the dielectric layer 12 and the internal electrode layer 11 are alternately laminated in multiple layers. A laminated ceramic fired body). In addition, an annealing treatment may be performed on the fired laminated ceramic fired body from the viewpoint of improving reliability by bringing oxygen into the interior of the dielectric layer and suppressing reoxidation of internal electrodes.

Then, the laminated ceramic capacitor 1 is manufactured by providing a pair of external electrodes 20 to the prepared laminated ceramic fired body. 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 . In addition, as a material of the external electrode 20, for example, copper, nickel, or alloys thereof can be preferably used. In addition, electronic components are not limited to laminated ceramic capacitors, and electronic components other than laminated ceramic capacitors may be used.

【Example】

Hereinafter, although this invention is demonstrated in detail based on an Example and a comparative example, this invention is not limited to an Example at all.

[Evaluation method]

(Change in viscosity of conductive paste)

Taking 24 hours from the production of the conductive paste as the reference time, the reference time was left at room temperature (25°C) for 1 day, 14 days, and 28 days from the reference time by the following method. The viscosity of the samples after that was measured. Then, the value ([ (viscosity after standing-viscosity after 24 hours from production)/viscosity after 24 hours from production]×100), and it was used as the change amount of viscosity. The viscosity of the conductive paste was measured under the condition of 10 rpm (shear rate=4sec ⁻¹ ) using a B-type viscometer manufactured by Brookfield. Moreover, it is more preferable that the change amount of the viscosity of an electroconductive paste is small. In addition, when the amount of change in the viscosity of the conductive paste after standing still for 28 days was 26% or less, the viscosity stability of the conductive paste was evaluated as "○", and when it exceeded 26%, it was evaluated as the conductive paste The viscosity stability of the material is "×".

(dry film density DFD)

The prepared conductive paste was placed on a PET film, and spread to a length of about 100 mm by an applicator having a width of 50 mm and a gap of 125 μm. The obtained PET film was dried at 120° C. for 40 minutes. After forming the dried body, the dried body was cut into four 2.54 cm (1 inch) squares. The thickness and weight were measured respectively, and the dry film density (average value) was calculated.

(Surface roughness)

The prepared conductive paste was screen-printed on a 2.54 cm (1 inch) square heat-resistant tempered glass, and dried at 120°C in the atmosphere for 1 hour, and a dry film with a film thickness of 1-3 μm in a size of 20 mm square was prepared accordingly. membrane. Based on the JIS B0601-2001 standard, the surface roughness Ra (arithmetic mean roughness), Rz (maximum height), Rp (maximum peak height), and Rt (maximum profile height) of the prepared dry film were measured.

(printability)

In the process of preparing the above-mentioned samples for surface roughness, whether or not bleeding and blurring occurred in the screen-printed 20 mm square pattern was checked visually, and the printability was evaluated. A case where the occurrence of bleeding, blurring, etc. was not confirmed was evaluated as "◯", and a case where bleeding, blurring, etc. were observed was evaluated as "×".

[use material]

(conductive powder)

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

(ceramic powder)

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

(Binder resin)

As the binder resin, ethyl cellulose resin and polyvinyl butyral resin (PVB resin) are used. In addition, the binder resin prepared as the carrier which melt|dissolved in terpineol was used.

(Dispersant)

(1) As an amino acid-based dispersant, a dispersant a represented by R ₁ =C ₁₇ H ₃₃ (straight-chain hydrocarbon group) in the above chemical formula (1) and a dispersant a represented by R 1 =C 17 in the above chemical formula ( ₁ ) is used. Dispersant b represented by C ₁₅ H ₂₉ (linear hydrocarbon group).

(2) As an amine-based dispersant, in the above chemical formula (2), R ₂ =C ₁₂ H ₂₅ , R ₃ =C ₂ H ₄ O, R ₄ =C ₂ H ₄ O, Y=1, Z= The dispersant c shown in 1, the dispersant d shown by R ₂ =C ₁₂ H ₂₅ , R ₄ =C ₂ H ₄ O, Y=0, Z=1 in the above chemical formula (2), and the dispersant d shown in the above chemical formula (2) Dispersant e represented by R ₂ =C ₁₈ H ₃₇ , R ₃ =C ₂ H ₄ O, R ₄ =C ₂ H ₄ O, Y=1, Z=1.

(Organic solvents)

As the organic solvent, terpineol was used.

[Example 1]

A total of 3% by mass of binder resin, 0.35% by mass of amino acid The amine-based dispersant, 0.05% by mass of the amine-based dispersant, and terpineol were blended so that the total amount was 100% by mass, and the above-mentioned materials were mixed to prepare a conductive paste. The viscosity of the prepared conductive paste, the dry film density and the surface roughness of the dry film were evaluated according to the above method. Table 1 shows the evaluation results.

[Examples 2 to 12, Comparative Examples 1 to 5]

Except having made content of the amino acid type dispersant and the amine type dispersant into the quantity shown in Tables 1-3, the electroconductive paste was prepared on the same conditions as Example 1. The amount of change in the viscosity of the prepared conductive paste, the dry film density, the surface roughness of the dry film, and the printability were evaluated by the methods described above. The evaluation results are shown in Tables 1-3. In addition, the parts by mass of the content of the amino acid-based dispersant and the parts by mass of the content of the amine-based dispersant in Tables 1 to 3 are ratios to 100 parts by mass of Ni powder. In addition, the parts by mass of the content of the amino acid-based dispersant and the mass % of the content of the amine-based dispersant in Tables 1 to 3 are ratios with respect to 100% by mass of the conductive paste.

[Evaluation results]

As shown in Table 1, when the conductive paste of the example was compared with the conductive pastes of Comparative Examples 1 to 3 containing only one of the amino acid-based dispersant or the amine-based dispersant, the dry film density , The surface roughness reaches the same level or is improved compared with it, and the variation of slurry viscosity with time is significantly reduced.

Also, as shown in Table 2, in Comparative Example 4 in which the content of the amino acid-based dispersant exceeded 2 parts by mass, although the temporal viscosity change of the slurry viscosity was small, bleeding occurred and printability decreased. Also, as shown in Table 3, in Comparative Example 5 in which the content of the amine-based dispersant exceeded 2 parts by mass, although the temporal viscosity change of the slurry viscosity was small, bleeding occurred and printability decreased.

【Industrial Utilization】

The conductive paste of the present invention has excellent viscosity stability over time and dry film density after coating, and is particularly suitable as a raw material for internal electrodes of laminated ceramic capacitors in chip parts of electronic equipment such as mobile phones and digital devices. .

1‧‧‧MLCC

10‧‧‧Ceramic laminate

11‧‧‧internal electrode layer

12‧‧‧dielectric layer

20‧‧‧External electrodes

21‧‧‧External electrode layer

22‧‧‧Electroplating layer

Claims (11)

A conductive paste comprising conductive powder, ceramic powder, dispersant, binder resin, and organic solvent, characterized in that the aforementioned dispersant contains 0.01 parts by mass based on 100 parts by mass of the aforementioned conductive powder More than 2 parts by mass of the amino acid-based dispersant shown in the following chemical formula (1), and, based on 100 parts by mass of the aforementioned conductive powder, contain 0.01 parts by mass or more of the following chemical formula (2 parts by mass) ) represented by an amine-based dispersant; relative to the entire conductive paste, containing the above-mentioned conductive powder in an amount of 40% by mass to 60% by mass; relative to the entire conductive paste, containing 0.45% by mass or more of the aforementioned amino acid Department of dispersants;

Wherein, in formula (1), _R represents the chain hydrocarbon group that carbon number is 10～20;

Wherein, in formula (2), R ₂ represents an alkyl, alkenyl or alkynyl group with 8 to 16 carbon atoms, R ₃ represents an oxyethylene group, an oxypropylene group, or a methylene group, and R ₄ represents an oxyethylene group _R3 and _R4 can be the same or different; the N atom in formula (2) is not directly bonded to the O atom in _R3 and _R4 , and Y is the number of 0 to 2 , Z is a number from 1 to 2. As the conductive paste described in item 1 of the scope of application, wherein, in the above chemical formula (1), R ₁ represents a straight-chain hydrocarbon group with 10 to 20 carbon atoms. The conductive paste as described in claim 1 or 2, wherein the above-mentioned dispersant is contained in an amount of 0.01 mass % or more and 3 mass % or less with respect to the whole conductive paste. The conductive paste described in claim 1 or 2 of the patent application, wherein the conductive powder contains at least one metal selected from the group consisting of Ni, Pd, Pt, Au, Ag, Cu, and alloys thereof powder. The conductive paste as described in Claim 1 or 2, wherein the conductive powder has an average particle diameter of not less than 0.05 μm and not more than 1.0 μm. In the conductive paste described in claim 1 or 2, the ceramic powder contains a perovskite oxide. The conductive paste as described in Claim 1 or 2, wherein the average particle size of the ceramic powder is not less than 0.01 μm and not more than 0.5 μm. The conductive paste described in claim 1 or 2, wherein the binder resin contains at least one of cellulose-based resins, acrylic resins, and butyral-based resins. The conductive paste as described in claim 1 or 2 of the patent application, wherein the above-mentioned conductive paste is used for internal electrodes of laminated ceramic parts. An electronic component is characterized in that it is an electronic component formed by using the conductive paste described in any one of items 1 to 9 of the scope of application. A laminated ceramic capacitor, characterized in that it has at least a laminate formed by laminating a dielectric layer and an internal electrode, and the aforementioned internal electrode uses the conductivity described in any one of claims 1 to 9 of the patent application slurry is formed.

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