TWI810336B - Conductive paste, electronic parts, and multilayer ceramic capacitors - Google Patents

Abstract

The present invention provides a conductive paste having high dry film surface smoothness and high dry film density, excellent dispersibility of conductive powder, and high adhesion when forming a laminate, and, The viscosity change with time is very small, and the viscosity stability is more excellent. The conductive paste contains conductive powder, ceramic powder, a dispersant, a binder resin, and an organic solvent, and the dispersant contains the amino acid-based dispersant represented by the general formula (1) described in the specification and the general formula described in the specification. For the amine dispersant represented by formula (2), the ratio of the amino acid dispersant to the aforementioned amine dispersant (amino acid dispersant/amine dispersant) is 1/4 or more by mass ratio In the range of /2 or less, the total content of the amino acid-based dispersant and the aforementioned amine-based dispersant is 0.7% by mass or more and 1.2% by mass or less with respect to the total amount of the conductive paste.

Description

Conductive paste, electronic parts, and multilayer 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 multilayer ceramic capacitors. A multilayer ceramic capacitor has a structure in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately laminated, and 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 as follows. First, on the surface of a 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 dried to form a dry film. . Next, the dry film and the green sheet are laminated so that they are alternately stacked, and heated and pressure-bonded to form an integrated laminated body. The laminate is cut, subjected to an organic binder removal treatment in an oxidative atmosphere or an inert atmosphere, 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 multilayer 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 reduction in the thickness 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 of the dispersant The point 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 The content of the inhibitor 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, the dry film obtained by printing and drying the conductive paste for internal electrodes on the surface of the green sheet is required to have a high density. For example, a metal ultrafine powder slurry has been proposed in Patent Document 3, which contains an organic solvent, a surfactant, and metal ultrafine particles, 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 ultrafine metal powder, based on 100 parts by mass of the above-mentioned ultrafine metal powder, containing more than 0.05 mass parts and less than 2.0 mass parts 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 improve the surface smoothness of the dried film after coating.

In view of such a situation, the object of the present invention is to provide an electroconductive paste having high dry film surface smoothness and high dry film density, excellent dispersibility of electroconductive powder, and excellent High adhesion, and the viscosity change with time is very small, and the viscosity stability is more excellent.

The first aspect of the present invention provides a conductive paste, which contains conductive powder, ceramic powder, dispersant, binder resin and organic solvent, characterized in that the dispersant contains amine represented by the following general formula (1) The ratio of amino acid dispersant and amine dispersant (amino acid dispersant/amine dispersant) by mass The ratio is in the range of not less than 1/4 and not more than 1/2, and the total content of the amino acid-based dispersant and the amine-based dispersant is not less than 0.7% by mass and not more than 1.2% by mass relative to the total amount of the conductive 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 oxyethylene group group or oxypropylene 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 , Y is the value of 0~2, Z It is a value from 1 to 2.)

In addition, in the general formula (1), R ₁ ideally represents a linear hydrocarbon group having 10 to 20 carbon atoms. In addition, the conductive powder preferably contains at least one metal powder selected from the group consisting of Ni, Pd, Pt, Au, Ag, Cu, and alloys of the above elements. Moreover, it is desirable to contain 40 mass % or more and 60 mass % or less of electroconductive powder with respect to the total amount of electroconductive paste. 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. In addition, 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 desirably contains at least one of cellulose-based resins, acrylic resins, and butyral-based resins. Moreover, the said electroconductive paste is ideally used for the internal electrode of a laminated ceramic capacitor.

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 having a laminate in which internal electrode layers and dielectric layers formed using the above-mentioned conductive paste are laminated.

The conductive paste of the present invention has a very small change in viscosity over time and is more excellent in viscosity stability. At the same time, it has excellent dispersibility of conductive powder, and has high surface smoothness and high viscosity in the dried film after coating. Dry film density. In addition, when forming thinned electrodes, the electrode pattern of electronic components such as laminated ceramic capacitors formed using the conductive paste of the present invention is also excellent in the adhesion of the conductive paste, and has good precision and uniform width. and thickness.

1‧‧‧Multilayer Ceramic Capacitors

10‧‧‧Ceramic laminate

11‧‧‧internal electrode layer

12‧‧‧dielectric layer

20‧‧‧External electrodes

21‧‧‧External electrode layer

22‧‧‧Electroplating layer

[FIG. 1A] is a perspective view showing a multilayer ceramic capacitor related to this embodiment.

[ Fig. 1B ] is a cross-sectional view showing a multilayer ceramic capacitor according to this embodiment.

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 Ni, Pd, Pt, Au, Ag, Cu, and alloys of the above elements 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 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, the Ni powder may contain S on the order of several hundred ppm in order to suppress violent gas generation due to partial thermal decomposition of the binder resin during the binder removal process.

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, for example, the smoothness and dry film density of the dry film can be improved. The average particle diameter is a value obtained by observation with a scanning electron microscope (SEM), and is obtained by measuring the particle diameters of a plurality of particles one by one from an image obtained by observing with a SEM at a magnification of 10,000 times. average value.

The content of the conductive powder is preferably 30% by mass or more and less than 70% by mass relative to the total amount of the conductive paste, more preferably 40% by mass or more and 60% by mass or less. When content of electroconductive powder exists in the said range, electroconductivity and dispersibility are excellent.

(ceramic powder)

The ceramic powder is not particularly limited. For example, in the case of a slurry 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 other atoms such as Sn, Pb, and Zr.

In the slurry for internal electrodes, a powder having the same composition as that of the dielectric ceramic powder constituting the green sheet of the laminated ceramic capacitor can be used. Thereby, 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. Such ceramic powders include, for example, ZnO, ferrite, PZT, BaO, Al ₂ O ₃ , Bi ₂ O ₃ , R (rare earth elements) ₂ O ₃ , TiO ₂ , and Nd ₂ in addition to the above. _O3 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 the particle diameters of a plurality of particles one by one from images obtained by observing with a SEM at a magnification of 50,000 times. value.

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 relative to the total amount of the conductive paste, more preferably not less than 5% by mass and not more than 20% by mass. 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, it is desirable to contain ethyl cellulose from the viewpoint of solubility in a solvent, combustion decomposability, and the like. In addition, when used as a slurry 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 bonding strength with a green sheet. One kind of binder resin may be used, and 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, 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 total amount of the 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.

The content of the organic solvent is preferably from 20% by mass to 60% by mass with respect to the total amount of the conductive paste, more preferably from 35% by mass to 55% by mass. 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 the general formula (1) and an amine-based dispersant represented by the general formula (2). In addition, the dispersant may contain dispersants other than the amino acid-based dispersant represented by the general formula (1) and the amine-based dispersant represented by the general formula (2).

As a result of studying various dispersants for dispersants used in conductive paste, the inventors of the present invention found that by combining the above two dispersants in a specific ratio, the conductive paste can be made The viscosity change with time is small, the viscosity stability is very excellent, and the dispersibility of the conductive powder is excellent, and the dry film after coating has high surface smoothness and high dry film density.

In addition, the inventors of the present invention found that the viscosity of the conductive paste can be further increased by combining the two dispersants in a specific ratio and setting the total content of the two dispersants to a specific amount. Stability and dispersibility, and excellent adhesion when forming a laminate.

Although the details of the reason are not clear, it is considered that the effect is brought about by the action of the amine group and carboxyl group present in the molecule of the dispersant to form a ligand on the metal atom of the conductive powder. Hereinafter, the dispersant used in this embodiment will be described.

The amino acid-based dispersant used in this embodiment has an N-acylamino acid skeleton and a chain hydrocarbon group having 10 to 20 carbon atoms, as represented by the following general formula (1).

(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. In addition, 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 having a double bond.

As the amino acid-based dispersant represented by the above formula (1), for example, commercially available amino acid-based dispersants satisfying the above characteristics can be selected and used. 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 general 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 oxyethylene group _R3 and _R4 can be the same or different. In addition, the N atom in formula (2) is not directly bonded to the O atom in _R3 and _R4 , and Y is a value of 0 to 2 , Z is a value 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 value of 0 to 2, and Z is a value of 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 terminal and (R ₃ ) _Y Adjacent H atoms are bonded. In addition, 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 terminal 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, alkenyl or alkynyl group with 8 to 16 carbon atoms, a hydrogen group, and -(R ₄ ) ₂ H The secondary amine constituted, the aforementioned -(R ₄ ) ₂ H is -(AO) ₂ H in which either an ethylene dioxide group or a propylene dioxide group is bonded to an H element.

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. Moreover, when Y is 2, the above-mentioned amine-based dispersant is a tertiary amine having -R ₂ , -(R ₃ ) ₂ H, and -(R ₄ ) _z H, and the above-mentioned -(R ₃ ) ₂ H is -(AO) ₂ H or -C ₂ H ₅ in which any one of ethylene dioxide, propylene oxide or ethylene is bonded to H element.

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

In terms of mass ratio, the ratio of the above-mentioned amino acid-based dispersant to the above-mentioned amine-based dispersant contained in the conductive paste (amino acid-based dispersant/amine-based dispersant) is not less than 1/4 and not more than 1/2 range. Especially when the ratio of the above-mentioned amino acid-based dispersant to the above-mentioned amine-based dispersant is 1/4 to 2/5, the conductive paste has very high viscosity stability.

When the lower limit of the ratio of the amino acid-based dispersant to the amine-based dispersant is 1/4 or more, the effect of improving the viscosity of the conductive paste over time can be further improved, and the dispersion of the conductive powder can be improved. properties, and has a higher dry film surface smoothness and a higher dry film density. In addition, when the upper limit of the ratio of the amino acid-based dispersant to the amine-based dispersant is 1/2 or less, the amine-based dispersant becomes relatively large, thereby greatly reducing the viscosity of the conductive paste. changes over time.

The total content of the amino acid-based dispersant represented by the formula (1) and the amine-based dispersant represented by the formula (2) is 0.7% by mass or more and 1.2% by mass or less with respect to the total amount of the conductive paste. When the total content of the above-mentioned amino acid-based dispersant and the above-mentioned amine-based dispersant is within the above-mentioned range, the dispersibility of the conductive paste is improved, the dry film density is high, and the smoothness of the surface is excellent. The film can be dried, and the sheet erosion and green sheet peeling failure caused by the residue of the dispersant can be suppressed.

When the lower limit of the total content of the amino acid-based dispersant and the above-mentioned amine-based dispersant is 0.7% by mass or more, the conductive In the slurry, the dispersibility can be further improved, the dry film smoothness and the dry film density can be higher, and the change with time of the viscosity of the conductive paste can be further reduced. In addition, when the upper limit of the total content of the above-mentioned amino acid-based dispersant and the above-mentioned amine-based dispersant is 1.2% by mass or less, the residual amount of the dispersant on the surface of the dry film is further reduced, and the hindrance during lamination and pressure bonding is suppressed. The peeling occurs due to the adhesion between the surface of the dry film and the surface of the green sheet.

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 high Molecular dispersant and so on. In addition, these dispersants may be used alone or in combination of two or more.

(conductive paste)

The conductive paste of this embodiment can be manufactured by preparing each said component and stirring and kneading with a mixer. At this time, if the dispersant is pre-coated on the surface of the conductive powder, the conductive powder can be fully dispersed without agglomeration, and the dispersant is spread all over the surface, making it easy to obtain a uniform conductive paste. In addition, it is also possible to dissolve the binder resin in the organic solvent for the carrier to prepare the organic vehicle, and add conductive powder, ceramic powder, organic vehicle and dispersant to the organic solvent for the slurry, and mix it with a mixer. Stirring and kneading are performed to prepare a conductive paste.

In addition, 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 carrier. The content of the organic solvent for the carrier is, for example, not less than 5 parts by mass and not more than 80 parts by mass 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 total amount of electroconductive paste.

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

In addition, the surface smoothness of the dried film formed by printing the conductive paste can be evaluated by the surface roughness. In addition, the surface roughness of the above-mentioned conductive paste can be measured by, for example, the method described in the examples (the method of performing the arithmetic mean height Sa based on the standard of ISO 25178 using VK-X120 manufactured by KEYENCE Corporation). Spend. When evaluated by the arithmetic mean height Sa, the value of the surface smoothness of the dry film is desirably 0.17 μm or less.

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

For a multilayer ceramic capacitor, it is desirable that the dielectric ceramic powder contained in the green sheet and the ceramic powder contained in the conductive paste have the same composition. The laminated ceramic capacitor manufactured 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 in a schematic form or changed in scale as appropriate. In addition, the position, direction, etc. of a component are demonstrated with reference to the XYZ rectangular coordinate system shown to FIG. 1A etc. suitably. 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).

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

Hereinafter, the manufacturing method of the laminated ceramic capacitor using the said electroconductive paste is demonstrated. First, a conductive paste is printed and dried on a green sheet to form a dry film. After laminating and pressure-bonding a plurality of green sheets having the dry film on the upper surface to obtain a laminate, the laminate is fired to integrate it, thereby producing alternate internal electrode layers 11 and dielectric layers 12 . The ceramic laminate 10 formed by building up layers. 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 that is an unfired ceramic sheet using a dielectric material is prepared. As the green sheet, for example, 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 sheet on a supporting film and drying to remove the solvent. In addition, the thickness 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 multilayer 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, from the viewpoint of the requirement for thinning the internal electrode layer 11 , the thickness of the conductive paste after printing is preferably such that the thickness of the dried film after drying is 1 μm or less.

Next, the green sheet is peeled off from the support film, laminated so that the green sheet and the dry film formed on one surface of the green sheet are alternately arranged, and then heated and pressurized to obtain a laminated body. Moreover, the structure which arrange|positions the protective green sheet which did not apply|coat the electroconductive paste further on both surfaces of a laminated body can also be made into it.

Next, after the laminate is cut into a predetermined size to form a green wafer, the green wafer is subjected to a binder removal process and fired in a reducing atmosphere to manufacture the ceramic laminate 10 . In addition, the atmosphere in the binder removal process is ideally the air or an 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, firing is carried out under a reducing atmosphere. In addition, the temperature when firing the laminated body is, for example, 1000°C to 1350°C. The holding time 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 carrier in the dry film is removed, and the nickel powder or the alloy powder mainly composed of nickel is sintered or melted to integrate, thereby forming the internal electrode layer 11, and further forming the dielectric layer 12 and the internal electrode layer 11. A laminated ceramic fired body formed by building up layers. In addition, from the viewpoint of improving reliability by taking oxygen into the interior of the dielectric layer and suppressing reoxidation of internal electrodes, an annealing treatment may be performed on the fired laminated ceramic fired body.

Next, 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 an alloy of the above elements can be preferably used. In addition, electronic components are not limited to multilayer ceramic capacitors, and may be electronic components other than multilayer ceramic capacitors.

【Example】

Hereinafter, the present invention will be described in detail based on examples and comparative examples, but the present invention is not limited by the examples.

〔Materials used〕

(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, as the binder resin, what was prepared as a carrier dissolved in terpineol was used.

(Dispersant)

(1) As the amino acid-based dispersant, a dispersant represented by R ₁ =C ₁₇ H ₃₃ (linear hydrocarbon group) in the above general formula (1) is used.

(2) As an amine-based dispersant, 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 shown in 1.

(Organic solvents)

As the organic solvent, terpineol was used.

[Example 1]

46% by mass of Ni powder, 11.5% by mass of ceramic powder, and a total of 3.2% by mass of binder resin (composed of ethyl cellulose resin and polyvinyl butyral) in the carrier were mixed so that the total amount was 100% by mass. aldehyde resin), 0.2% by mass of an amino acid-based dispersant, 0.6% by mass of an amine-based dispersant, and terpineol (organic solvent) as the balance, and these materials were mixed to prepare a conductive paste. The viscosity stability, dispersibility (dry film density, surface roughness of dry film) and adhesiveness of the prepared conductive paste were evaluated by the following method. Table 1 shows the evaluation results.

〔Evaluation method〕

(Viscosity stability: change in viscosity of conductive paste)

Taking 24 hours after the production of the conductive paste as the reference time, the reference time was left to stand at room temperature (25°C) for 7 days, 14 days, and 28 days from the reference time by the following method. The viscosity of the samples after that was measured. Next, 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. The change in viscosity of the conductive paste after standing for 28 days was marked as "A" when it was less than 10%, and "B" when it exceeded 10% to evaluate the viscosity stability of the conductive paste .

(Dispersibility: surface roughness of dry film, dry film density)

<Surface Roughness>

The prepared conductive paste was screen-printed on a 2.54 cm (1 inch) square of heat-resistant tempered glass, and dried at 120°C in the air for 1 hour to prepare a dry film of 20 mm square and a film thickness of 1 to 3 μm. When the dispersibility of an electroconductive paste is favorable, the surface of a dry film becomes a smooth film. When the dispersibility is poor, aggregation occurs in the conductive paste, the surface of the dried film is roughened, and the surface smoothness is lowered. Here, the surface roughness Sa (arithmetic mean height) and Sz (maximum height) of the prepared dry film were measured using a laser microscope (Keyence VK-X120) in accordance with ISO 25178. The smaller the value of the surface roughness Sa (arithmetic mean height) and Sz (maximum height), the smoother the surface of the dry film is.

(Dry Film Density (DFD: Dry Film Density))

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. After drying the obtained PET film at 120° C. for 40 minutes to form a dried body, the dried body was cut into four 2.54 cm (1 inch) squares. Thickness and mass were measured respectively, and the dry film density (average value) was calculated. When the dispersibility of the electroconductive paste is low and the electroconductive powder aggregates, the dry film density may fall, and electrical characteristics etc. may be inferior. The higher the dry film density, the better the dispersibility.

<Evaluation of dispersion>

The case where the surface roughness Sa (arithmetic average height) of the above-mentioned dry film is 0.17 μm or less and the dry film density DFD is 5.50 g/ ^cm The case where the average height) is greater than 0.17 μm and the case where the dry film density DFD is less than 5.50 g/cm ³ or the case where both are satisfied is recorded as "B" to evaluate the dispersibility.

(adhesive)

The prepared conductive paste was printed (coated) on a green sheet by a screen printing method and dried to prepare a plurality of sheets in which a dry film was formed on the green sheet. Five layers of the above sheets were laminated, and subjected to thermocompression bonding at 80° C. and a pressure of 100 kg/cm ² for 3 minutes to form a laminate. In the obtained laminate, when the adhesiveness between the dry film surface (electrode layer surface) and the bottom surface of the green sheet laminated thereon was weak and peeling occurred at one or more places, it was marked as "×", except In addition, the case where peeling did not occur was marked as "(circle)", and adhesiveness was evaluated.

[embodiment 2,3, comparative example 1,2]

An electroconductive paste was prepared on the same conditions as in Example 1 except that the content of the amino acid-based dispersant and the amine-based dispersant was changed to the amounts shown in Table 1 and the compounding ratio of the dispersant was changed. 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 adhesiveness were evaluated by the above-mentioned method. Table 1 shows the evaluation results.

[embodiment 4～6, comparative example 3,4]

In addition to changing the total content of the dispersant in the conductive paste by changing the content of the amino acid-based dispersant and the amine-based dispersant to the amounts shown in Table 2 while keeping the compounding ratio of the dispersant constant, A conductive paste was prepared under the same conditions as in 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 adhesiveness were evaluated by the above-mentioned method. Table 2 shows the evaluation results.

〔Evaluation results〕

As shown in Table 1 and Table 2, the conductive paste of the example has a dry film density of 5.5 g/cm ³ or more, a surface roughness Sa (arithmetic mean height) of 0.17 μm or less, and no peeling is observed on the laminate , showing good dispersion and adhesion. In addition, in the conductive paste of the example, the change over time of the viscosity of the conductive paste was very low at 5.4% or less after 28 days, and it was found that the viscosity stability was very good.

In contrast, the conductive paste of Comparative Example 1, which has a low proportion of amino acid dispersant and amine dispersant and contains more amine dispersant, has good viscosity stability, but the dry film density is 5.5g /cm ³ or less, the surface roughness Sa exceeds 0.17 μm, and the dispersibility is lower than that of the conductive paste of the examples. In addition, the surface roughness Sz (maximum height) also exhibited a slightly larger value than the Examples. In addition, the amount of change in the viscosity of the conductive paste after 28 days of the conductive paste of Comparative Example 2, which has a high ratio of amino acid-based dispersant to amine-based dispersant and contains more amino acid-based dispersant It was 16.7%, a change of more than 10%.

In addition, the conductive paste of Comparative Example 3 in which the total content of the amino acid-based dispersant and the amine-based dispersant is less than 0.7% by mass has lower dispersibility than the conductive paste of the example, and its viscosity stability is comparable to that of the embodiment. case is also lower. In addition, with regard to the conductive paste of Comparative Example 4 in which the total content of the amino acid-based dispersant and the amine-based dispersant exceeds 1.2% by mass, the laminate produced using the conductive paste of Comparative Example 4 may Peeling occurred in , and the adhesiveness decreased compared with the conductive paste of the Example.

In addition, the technical scope of the present invention is not limited to the aspects described in the above-mentioned embodiment and the like. In some cases, one or more of the requirements described in the above-mentioned embodiment and the like may be omitted. In addition, the requirements described in the above-mentioned embodiments and the like can be appropriately combined. In addition, as long as the law allows, the contents of Japanese Patent Application No. 2018-139501, which is a Japanese patent application, and all documents cited in this specification are cited as part of the description herein.

【Industrial Utilization】

The conductive paste related to this embodiment is particularly suitable for use as a mobile phone, a mobile phone, a Raw materials for internal electrodes of chip parts (electronic parts) of electronic equipment such as digital equipment, and multilayer ceramic capacitors.

Claims (10)

A kind of conductive slurry, it contains conductive powder, ceramic powder, dispersant, binder resin and organic solvent, it is characterized in that: above-mentioned dispersant contains aminoacid dispersant represented by following general formula (1) and The amine-based dispersant represented by the following general formula (2), the ratio of the aforementioned amino acid-based dispersant to the aforementioned amine-based dispersant (amino acid-based dispersant/amine-based dispersant) is 1 in mass ratio In the range of /4 to 1/2, the total content of the amino acid-based dispersant and the amine-based dispersant is 0.7% by mass to 1.2% by mass relative to the total amount of the conductive paste,

Wherein, in formula (1), R ₁ represents a straight-chain hydrocarbon group with 10 to 20 carbon atoms, [Chemical 2]

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 Or oxypropylene, _R3 and _R4 can 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 , and Y is 0~2 Value, Z is a value from 1 to 2. The conductive paste described in claim 1, wherein the conductive powder contains at least one metal powder selected from Ni, Pd, Pt, Au, Ag, Cu, and alloys of the above elements. The conductive paste described in claim 1 or 2, wherein the conductive powder is contained in an amount of 40 mass % or more and 60 mass % or less with respect to the total amount of the conductive paste. 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 claims, wherein the conductive paste is used for internal electrodes of laminated ceramic capacitors. An electronic component is characterized in that it is an electronic component formed by using the conductive paste described in item 1 or 2 of the scope of application. A laminated ceramic capacitor characterized by having a laminate formed by laminating internal electrode layers and dielectric layers formed using the conductive paste described in claim 8.

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