JP2019046781A - Conductive paste and methods for manufacturing electronic component and multilayer ceramic capacitor - Google Patents

Abstract

To provide a conductive paste or the like which has a viscosity suitable for gravure printing and is excellent in paste dispersibility.SOLUTION: The conductive paste contains a conductive powder, a dispersant, a binder resin, and an organic solvent. The dispersant contains an amino acid-based dispersant having a molecular weight of 5,000 or less. The binder resin contains an acetal-based resin. The organic solvent contains a glycol ether-based solvent.SELECTED DRAWING: None

Description

  The present invention relates to a conductive paste and a method of manufacturing an electronic component and a multilayer ceramic capacitor.

  With the miniaturization and high performance of electronic devices such as mobile phones and digital devices, miniaturization and high capacity of electronic components including multilayer ceramic capacitors and the like are desired. A multilayer ceramic capacitor has a structure in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately stacked, and miniaturization and high capacity can be achieved by thinning the dielectric layers and the internal electrode layers. Can be

The multilayer ceramic capacitor is manufactured, for example, as follows. First, a paste for an internal electrode containing a conductive powder, a binder resin, an organic solvent and the like on the surface of a dielectric green sheet containing a dielectric powder such as barium titanate (BaTiO ₃ ) and a binder resin (conductive Pastes printed in a predetermined electrode pattern are stacked in multiple layers to obtain a laminate in which internal electrodes and dielectric green sheets are stacked in multiple layers. Next, this laminated body is thermocompression-bonded and integrated to form a crimped body. The pressure-bonded body is cut, subjected to a deorganic binder treatment in an oxidizing atmosphere or an inert atmosphere, and then fired to obtain a fired chip. Subsequently, the paste for external electrodes is apply | coated to the both ends of a baking chip | tip, after baking, nickel plating etc. are given to the surface of an external electrode, and a laminated ceramic capacitor is obtained.

  Conventionally, screen printing has been generally used as a printing method to be used when printing conductive paste on a dielectric green sheet, but from the demand for miniaturization of electronic devices, reduction in thickness, and improvement in productivity. It is required to print a finer electrode pattern with high productivity.

  Gravure which is a continuous printing method in which a conductive paste is filled in a recess provided in a plate and pressed against a surface to be printed as one of the printing methods of the conductive paste, thereby transferring the conductive paste from the plate. A printing method has been proposed. The gravure printing method has a high printing speed and is excellent in productivity. In the case of using the gravure printing method, it is necessary to appropriately select the binder resin, the dispersing agent, the solvent and the like in the conductive paste to adjust the properties such as viscosity to the range suitable for the gravure printing.

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

Moreover, in patent document 2, it is an electroconductive paste used in order to form by gravure similarly to the said patent document 1, Comprising: 30-70 weight% of a solid component containing metal powder, and 1-10 weight% A thixotropic fluid comprising a resin component, 0.05 to 5% by weight of a dispersant, and a solvent component as the balance, and having a viscosity of 1 Pa · s or more at a shear rate of 0.1 (s ⁻¹ ), A conductive paste is described in which the viscosity change rate at a shear rate of 10 (s ⁻¹ ) is 50% or more based on the viscosity at a shear rate of 0.1 (s ⁻¹ ).

According to the above Patent Documents 1 and 2, these conductive pastes are thixotropic fluids having a viscosity of 1 Pa · s or more at a shear rate of 0.1 (s ⁻¹ ), and stabilized at high speed in gravure printing It is believed that continuous printability can be obtained, and multilayer ceramic electronic components such as multilayer ceramic capacitors can be manufactured with good production efficiency.

  Further, Patent Document 3 discloses a conductive material for a laminated ceramic capacitor internal electrode including a conductive powder (A), an organic resin (B), an organic solvent (C), an additive (D), and a dielectric powder (E). Paste, the organic resin (B) is composed of polyvinyl butyral having a degree of polymerization of 10000 to 50000 and ethylcellulose having a weight average molecular weight of 10000 to 100000, and the organic solvent (C) is propylene glycol monobutyl ether, Or a mixed solvent of propylene glycol monobutyl ether and propylene glycol methyl ether acetate, or a mixed solvent of propylene glycol monobutyl ether and mineral spirit, and the additive (D) comprises a separation inhibitor and a dispersant, and the separation Polycarboxylic acid polymers as inhibitors Properly gravure printing conductive paste made of a composition comprising a salt of a polycarboxylic acid. According to Patent Document 3, it is considered that this conductive paste has a viscosity suitable for gravure printing, improves the uniformity and stability of the paste, and has a good drying property.

JP 2003-187638 A JP 2003-242835 A JP 2012-174797 A

  With the thinning of the internal electrode layer in recent years, the conductive powder also tends to be reduced in particle size. If the particle size of the conductive powder is small, the specific surface area of the particle surface will be large, so the surface activity of the conductive powder (metal powder) may be high, and the dispersibility of the conductive paste may be lowered. A conductive paste having dispersibility is required.

  In addition, when the conductive paste is printed using a gravure printing method, a paste viscosity lower than that of the screen printing method is required, so the conductive powder having a relatively large specific gravity settles, and the dispersibility of the paste decreases. It is conceivable. The conductive pastes described in Patent Documents 1 and 2 improve the dispersibility of the paste by removing lumps in the conductive paste using a filter, but the lumps are removed Manufacturing process is likely to be complicated.

  An object of the present invention is to provide a conductive paste which has a paste viscosity suitable for gravure printing and is excellent in the dispersibility and productivity of the paste.

  A first aspect of the present invention is a conductive paste containing a conductive powder, a dispersant, a binder resin, and an organic solvent, the dispersant containing an amino acid-based dispersant having a molecular weight of 5000 or less, and the binder resin A conductive paste is provided which contains an acetal resin and the organic solvent contains a glycol ether solvent.

  The amino acid based dispersant is preferably represented by the following general formula (1).

（ただし、一般式（１）中、Ｒ_１は、炭素数１０以上２０以下の直鎖アルキル基又は炭素数１０以上２０以下の直鎖アルケニル基である。）

(However, in the general formula (1), R ₁ is a linear alkyl group having 10 to 20 carbon atoms or a linear alkenyl group having 10 to 20 carbon atoms.)

  The amino acid-based dispersant is preferably contained in an amount of 0.01 to 2 parts by mass with respect to 100 parts by mass of the conductive powder. The glycol ether solvent is preferably contained in an amount of 30 parts by mass to 50 parts by mass with respect to 100 parts by mass of the conductive powder. In addition, the dispersant may further contain a basic dispersant. The dispersant is preferably contained in an amount of 0.01 parts by mass or more and 2 parts by mass or less with respect to 100 parts by mass of the conductive powder.

The conductive powder preferably contains at least one metal powder selected from Ni, Pd, Pt, Au, Ag, Cu and alloys thereof. Further, the conductive paste preferably contains a ceramic powder. The ceramic powder preferably contains a perovskite oxide. Further, the ceramic powder preferably has an average particle diameter of 0.01 μm or more and 0.5 μm or less. The conductive powder preferably has an average particle diameter of 0.05 μm or more and 1.0 μm or less. The conductive paste is preferably for the internal electrode of the laminated ceramic component. The conductive paste, the viscosity of the shear rate 100 sec ^-1 is not higher than 0.8 Pa · S, it is preferable that the viscosity of the shear rate 10000 sec ^-1 is less than 0.18Pa · S.

  According to a second aspect of the present invention, there is provided a method of manufacturing an electronic component formed using the above conductive paste.

  According to a third aspect of the present invention, there is provided a method for producing a multilayer ceramic capacitor, comprising at least a laminate in which a dielectric layer and an internal electrode are laminated, wherein the internal electrode is formed using the conductive paste. Be done.

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

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

[Conductive paste]
The conductive paste of the present embodiment contains a conductive 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 for example, at least one powder selected from Ni, Pd, Pt, Au, Ag, Cu, and alloys thereof can be used. Among these, in view of conductivity, corrosion resistance and cost, powder of Ni or its alloy is preferable. As the Ni alloy, for example, an alloy of Ni with at least one or more elements selected from the group consisting of Mn, Cr, Co, Al, Fe, Cu, Zn, Ag, Pt, and Pd may be used. it can. The content of Ni in the Ni alloy is, for example, 50% by mass or more, preferably 80% by mass or more. Further, the Ni powder may contain about several hundreds ppm of S in order to suppress rapid gas generation due to partial thermal decomposition of the binder resin at the time of binder removal processing.

  The average particle diameter of the conductive powder is preferably 0.05 μm or more and 1.0 μm or less, and more preferably 0.1 μm or more and 0.5 μm or less. When the average particle diameter of the conductive powder is in the above range, it can be suitably used as a paste for the internal electrode of the laminated ceramic capacitor which has been made thin, and for example, the smoothness and the dry film density of the dry film are improved. An average particle diameter is a value calculated | required from observation by a scanning electron microscope (SEM), and says the particle size of 50% of the integration value in particle size distribution.

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

(Ceramic powder)
The conductive paste may include ceramic powder. The ceramic powder is not particularly limited. For example, when it is a paste for an internal electrode of a laminated ceramic capacitor, a known ceramic powder is appropriately selected depending on the type of the laminated ceramic capacitor to be applied. The ceramic powder includes, for example, a perovskite-type oxide containing Ba and Ti, preferably barium titanate (BaTiO ₃ ). In addition, a ceramic powder may use one type and may use two or more types.

  As the ceramic powder, ceramic powder containing barium titanate as a main component and oxide as a minor component may be used. As an oxide, the oxide which consists of 1 or more types chosen from Mn, Cr, Si, Ca, Ba, Mg, V, W, Ta, Nb and rare earth elements is mentioned.

Further, as a ceramic powder, for example, a ceramic powder of a perovskite type oxide ferroelectric substance in which Ba atoms or Ti atoms of barium titanate (BaTiO ₃ ) are substituted with other atoms, for example, Sn, Pb, Zr, etc. It can also be done.

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

  The average particle size of the ceramic powder is, for example, not less than 0.01 μm and not more than 0.5 μm, and preferably not less than 0.01 μm and not more than 0.3 μm. When the average particle diameter of the ceramic powder is in the above range, a sufficiently thin and thin uniform internal electrode can be formed when used as a paste for an internal electrode. An average particle diameter is a value calculated | required from observation by a scanning electron microscope (SEM), and says the particle size of 50% of the integration value in particle size distribution.

  The content of the ceramic powder is preferably 1 part by mass to 30 parts by mass, and more preferably 3 parts by mass to 30 parts by mass, with respect to 100 parts by mass of the conductive powder.

  The content of the ceramic powder is preferably 1% by mass to 20% by mass, and more preferably 3% by mass to 20% by mass, with respect to the total amount of the conductive paste.

(Binder resin)
The binder resin contains an acetal resin. As the acetal resin, a butyral resin such as polyvinyl butyral is preferable. When the binder resin contains an acetal resin, it can be adjusted to a viscosity suitable for gravure printing, and can further improve the adhesion strength with the green sheet. The binder resin may contain, for example, 20% by mass or more, 30% by mass or more of the acetal resin with respect to the entire binder resin, or may be composed only of the acetal resin.

  The content of the acetal resin is preferably 1 to 10 parts by mass, and more preferably 1 to 8 parts by mass, with respect to 100 parts by mass of the conductive powder.

  The binder resin may also contain other resins below the acetal resin. The other resin is not particularly limited, and known resins can be used. Other resins include, for example, cellulose resins such as methyl cellulose, ethyl cellulose, ethyl hydroxyethyl cellulose, nitrocellulose, acrylic resins, etc. Among them, ethyl cellulose is preferred from the viewpoint of solubility in solvents, combustion decomposition, etc. preferable. The molecular weight of the binder resin is, for example, about 2,000 to 200,000.

  The content of the binder resin is preferably 1 to 10 parts by mass, and more preferably 1 to 8 parts by mass, with respect to 100 parts by mass of the conductive powder.

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

(Organic solvent)
The organic solvent contains at least one of a glycol ether solvent and an acetate solvent, and preferably contains a glycol ether solvent.

  Examples of glycol ether solvents include (di) ethylene glycol ethers such as diethylene glycol mono-2-ethylhexyl ether, ethylene glycol mono-2-ethylhexyl ether, diethylene glycol monohexyl ether, ethylene glycol monohexyl ether, and propylene glycol Propylene glycol monoalkyl ethers such as monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether and the like can be mentioned. Among them, propylene glycol monoalkyl ethers are preferable, and propylene glycol monobutyl ether is more preferable. When the organic solvent contains a glycol ether-based solvent, it is excellent in compatibility with the above-described binder resin, and excellent in drying property.

  The organic solvent may contain, for example, 25% by mass or more, 50% by mass or more of the glycol ether-based solvent, or may consist of only the glycol ether-based solvent with respect to the entire organic solvent. Moreover, a glycol ether solvent may be used individually by 1 type, and may use 2 or more types together.

  Examples of acetate solvents include dihydroterpinyl acetate, isobornyl acetate, isobornyl propionate, isobornyl butyrate, isobornyl isobutyrate, ethylene glycol monobutyl ether acetate, dipropylene glycol methyl ether Acetate, glycol ether acetates such as 3-methoxy-3-methylbutyl acetate, 1-methoxypropyl-2-acetate and the like can be mentioned.

  When the organic solvent contains an acetate solvent, for example, at least one acetate type selected from dihydroterpinyl acetate, isobornyl acetate, isobornyl propionate, isobornyl butyrate and isobornyl isobutyrate. It may contain a solvent (A). Among these, isobornyl acetate is more preferable. When the acetate-based solvent (A) is contained, the acetate-based solvent (A) is preferably contained in an amount of 90% by mass to 100% by mass, and more preferably 100% by mass, based on the whole organic solvent.

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

  In the case of a mixed solution containing an acetate solvent (A) and an acetate solvent (B), the organic solvent preferably contains 50% by mass or more and 90% by mass or less of the acetate solvent (A) based on the whole organic solvent And more preferably 60% by mass or more and 80% by mass or less. In the case of the above liquid mixture, the organic solvent contains 10% by mass to 50% by mass, more preferably 20% by mass to 40% by mass of the acetate solvent (B) based on 100% by mass of the total organic solvent. Do.

  The organic solvent may also contain other organic solvents other than glycol ether solvents and acetate solvents. It does not specifically limit as another organic solvent, The well-known organic solvent which can melt | dissolve the said binder resin can be used. Other organic solvents include, for example, acetate solvents such as ethyl acetate, propyl acetate, isobutyl acetate and butyl acetate, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, terpene solvents such as terpineol and dihydroterpineol, tridecane, And aliphatic hydrocarbon solvents such as nonane and cyclohexane. Among them, aliphatic hydrocarbon solvents are preferable, and among the aliphatic hydrocarbon solvents, mineral spirit is more preferable. The other organic solvents may be used alone or in combination of two or more.

  The organic solvent can contain, for example, a glycol ether solvent as a main solvent, and an aliphatic hydrocarbon solvent as a cosolvent. In this case, the glycol ether-based solvent is contained in an amount of preferably 30 to 50 parts by mass, more preferably 40 to 50 parts by mass with respect to 100 parts by mass of the conductive powder, and an aliphatic hydrocarbon solvent Preferably, 20 parts by weight or more and 80 parts by weight or less, more preferably 20 parts by weight or more and 40 parts by weight or less, per 100 parts by weight of the conductive powder.

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

  20 mass% or more and 50 mass% or less are preferable with respect to the conductive paste whole quantity, and, as for content of the organic solvent, 25 mass% or more and 45 mass% or less are more preferable. When the content of the organic solvent is in the above range, the conductivity and the dispersibility are excellent.

(Dispersant)
The conductive paste of the present embodiment contains an amino acid based dispersant. As a result of examining the various dispersants for the dispersant used for the conductive paste, the inventor of the present invention includes the amino dispersant in combination with the binder resin and the organic solvent described above, but the reason is unknown. It has been found that when the internal electrode is formed, the generation of lumps is greatly suppressed, and the dispersibility of the paste is improved.

  In addition, the amino acid based dispersant has a carboxyl group and an amide bond. Since the amino acid dispersant has a carboxyl group, the details are unknown, but the carboxyl group is adsorbed on the surface of the conductive powder or the like to neutralize the surface potential or inactivate the hydrogen bonding site, and It is surmised that the specific steric structure as described above of the site other than the carboxyl group can effectively suppress the aggregation of the conductive powder etc., and the dispersibility of the paste can be further improved.

  The amino acid-based dispersant is more preferably a low molecular weight dispersant that exhibits acidity having a molecular weight of 5,000 or less, preferably 1,000 or less, and a molecular weight of 500 or less. On the other hand, the lower limit of the molecular weight is preferably 100 or more, more preferably 200 or more. The amino acid dispersant may be used alone or in combination of two or more.

  Amino Acid Dispersant The acid dispersant preferably includes an amino acid dispersant represented by the following general formula (1).

In the above general formula (1), R ₁ represents a linear alkyl group having 10 to 20 carbon atoms or a linear alkenyl group having 10 to 20 carbon atoms. R ₁ preferably has 15 to 20 carbon atoms, and more preferably 17 carbon atoms. R ₁ may be a linear alkyl group or a linear alkenyl group having a carbon double bond, preferably a linear alkenyl group.

  The amino acid-based dispersant is preferably contained in an amount of 0.01 to 2 parts by mass, and more preferably 0.05 to 1.5 parts by mass, with respect to 100 parts by mass of the conductive powder. More preferably, the content is 0.05 parts by mass or more and 1.0 parts by mass or less. When the content of the amino acid-based dispersant is in the above range, the dispersibility of the conductive powder in the conductive paste is excellent. In addition, the amino acid based dispersant tends to lower the viscosity of the conductive paste and improve the printability by increasing the content within the above range, but the drying property of the conductive paste decreases, and the sheet There is also a tendency that an attack tends to occur or the print shape can not be maintained. For this reason, in actual use, it is sufficient to select the composition of the content to be a combination of appropriate balance according to the requirement of the electronic component using the conductive paste.

  The amino acid-based dispersant is contained, for example, at 3% by mass or less based on the entire conductive paste. The upper limit of the content of the amino acid-based dispersant is preferably 2% by mass or less, more preferably 1.5% by mass or less, and still more preferably 1% by mass or less. The lower limit of the content of the amino acid based dispersant is not particularly limited, but is, for example, 0.01% by mass or more, and preferably 0.05% by mass or more.

  Some organic solvents cause sheet attack or green sheet peeling failure when used in combination with a binder resin, but the occurrence of these problems is suppressed by containing a specific amount of an amino acid based dispersant. it can. In addition, a conductive paste containing an acetal resin as the binder resin and a glycol ether solvent as the organic solvent does not use an amino acid type dispersant, but uses another acid type dispersant such as a phosphoric acid type dispersant or the like. In the case, a lump may be generated, but when the conductive paste of the present embodiment is used, the generation of a lump can be extremely suppressed.

  The amino acid-based dispersant can be selected and used from commercially available products, for example, which satisfy the above characteristics. In addition, the amino acid based dispersant may be produced so as to satisfy the above-mentioned characteristics using a conventionally known production method.

  The conductive paste may contain other acid dispersants other than the amino acid dispersant. Examples of other acid-based dispersants include higher fatty acids and polymer surfactants. These dispersants may be used alone or in combination of two or more.

  The higher fatty acid may be unsaturated carboxylic acid or saturated carboxylic acid, and is not particularly limited, but carbons such as stearic acid, oleic acid, behenic acid, myristic acid, palmitic acid, linoleic acid, lauric acid, linolenic acid, etc. There are 11 or more. Among these, oleic acid or stearic acid is preferred.

  Other acid-based dispersants are not particularly limited, and alkyl monoamine salt type represented by monoalkylamine salt, and alkyl diamine salt type represented by N-alkyl (C14 to C18) propylene diamine dioleate. , Alkyl trimethyl ammonium salt type represented by alkyl trimethyl ammonium chloride, alkyl dimethyl benzyl ammonium salt type represented by coc alkyl dimethyl benzyl ammonium chloride, quaternary ammonium salt type represented by alkyl dipolyoxyethylene methyl ammonium chloride Alkyl pyridinium salt type, tertiary amine type represented by dimethyl stearyl amine, polyoxyethylene alkyl amine type represented by polyoxypropylene / polyoxyethylene alkylamine, N, N , N'- tris (2-hydroxyethyl) -N- alkyl (C14~18) 1,3- surfactant selected from polyoxyethylene-added diamine represented by diamino propane.

  In addition, the dispersant may contain a dispersant other than the acid dispersant. Dispersants other than acid-based dispersions include basic dispersants, nonionic dispersants, amphoteric dispersants and the like. These dispersants may be used alone or in combination of two or more.

  Examples of the basic dispersant include aliphatic amines such as laurylamine, polyethylene glycol laurylamine, rosinamine, cetylamine, myristylamine and stearylamine. When the conductive paste further contains a basic dispersion in combination with the amino acid-based dispersant, it is possible to achieve both viscosity stability with time and paste dispersibility at a very high level.

  The base-based dispersant may be contained, for example, in an amount of 0.01 parts by mass or more and less than 2 parts by mass, preferably 0.02 parts by mass or more and 1 part by mass or less based on 100 parts by mass of the conductive powder. Good. The base dispersant can be contained, for example, in an amount of about 10 parts by mass to about 300 parts by mass, preferably 50 parts by mass to 150 parts by mass, with respect to 100 parts by mass of the amino acid-based dispersant. When the basic dispersion is contained in the above range, the viscosity stability with time of the paste is superior.

  The base dispersant is contained, for example, in an amount of 0% by mass or more and 2.5% by mass or less, preferably 0% by mass or more and 1.0% by mass or less, more preferably 0.1% by mass, based on the entire conductive paste. More than 1.0 mass% content is contained, More preferably, 0.1 mass% or more and 0.8 mass% or less content is contained. When the basic dispersion is contained in the above range, the viscosity stability with time of the paste is superior.

  In the conductive paste, the content of the dispersant (whole) containing the amino acid-based dispersant is, for example, preferably 0.2 parts by mass or more and 2 parts by mass or less with respect to 100 parts by mass of the conductive powder. When the content of the dispersant (overall) exceeds the above range, the drying property of the conductive paste may be deteriorated, a sheet attack may occur, or the green sheet may not be peeled off from the backing PET film.

(Other ingredients)
The conductive paste of the present embodiment may contain other components other than the above components, as necessary. As other components, for example, conventionally known additives such as antifoaming agents, dispersing agents, plasticizers, surfactants and thickeners can be used.

(Conductive paste)
The method for producing the conductive paste of the present embodiment is not particularly limited, and a conventionally known method can be used. The conductive paste can be produced, for example, by stirring and kneading the above-mentioned components with a three-roll mill, a ball mill, a mixer or the like. At this time, when a dispersant is previously applied to the surface of the conductive powder, the conductive powder is sufficiently loosened without aggregation, and the dispersant is spread on the surface, so that it is easy to obtain a uniform conductive paste. In addition, after dissolving the binder resin in a part of the organic solvent to prepare an organic vehicle, after adding the conductive powder, the ceramic powder, the dispersing agent, and the organic vehicle to the organic solvent for paste adjustment The mixture may be stirred and kneaded to prepare a conductive paste.

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

In addition, the conductive paste preferably has a viscosity at a shear rate of 10000 sec- ¹ and is 0.18 Pa · S or less. When the viscosity at a shear rate of 10000 sec ^-1 is in the above range, it can be suitably used as a conductive paste for gravure printing. If the above range is exceeded, the viscosity may be too high to be suitable for gravure printing. The lower limit of the viscosity at a shear rate of 10000 sec ⁻¹ is not particularly limited, and is, for example, 0.05 Pa · S or more.

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

  In the laminated ceramic capacitor, preferably, the dielectric ceramic powder contained in the dielectric green sheet and the ceramic powder contained in the conductive paste are powders having the same composition. In the laminated ceramic device manufactured using the conductive paste of the present embodiment, even if the thickness of the dielectric green sheet is, for example, 3 μm or less, the sheet attack and the peeling failure of the green sheet are suppressed.

[Electronic parts]
Hereinafter, embodiments of the electronic component and the like of the present invention will be described with reference to the drawings. In the drawings, they may be represented schematically or may be represented by changing the scale as appropriate. Further, the positions, directions, and the like of the members will be appropriately described with reference to an XYZ orthogonal coordinate system shown in FIG. In this XYZ orthogonal coordinate system, the X direction and the Y direction are horizontal directions, and the Z direction is a vertical direction (vertical direction).

  FIGS. 1A and 1B are views showing a laminated ceramic capacitor 1 which is an example of an electronic component according to an embodiment. The multilayer ceramic capacitor 1 includes a laminated body 10 in which dielectric layers 12 and internal electrode layers 11 are alternately laminated, and an external electrode 20.

  Hereinafter, the manufacturing method of the laminated ceramic capacitor using the said conductive paste is demonstrated. First, an internal electrode layer 11 made of a conductive paste is formed by printing on a dielectric layer 12 made of a ceramic green sheet, and a plurality of dielectric layers having the internal electrode layer on the top are laminated by pressure bonding. After the laminate 10 is obtained, the laminate 10 is fired and integrated to produce a laminated ceramic fired body (not shown) that is to be a ceramic capacitor main body. Thereafter, the laminated ceramic capacitor 1 is manufactured by forming a pair of external electrodes at both ends of the ceramic capacitor main body. A more detailed description will be given below.

  First, a ceramic green sheet which is a non-fired ceramic sheet is prepared. As this ceramic green sheet, for example, a dielectric film layer paste 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 etc. What apply | coated in a sheet form on a support film, was made to dry, and the solvent was removed etc. are mentioned. The thickness of the dielectric layer formed of the ceramic green sheet is not particularly limited, but is preferably 0.05 μm or more and 3 μm or less from the viewpoint of demand for miniaturization of the multilayer ceramic capacitor.

  Next, the above-mentioned conductive paste is printed and coated on one side of this ceramic green sheet using a gravure printing method, and a plurality of those on which the internal electrode layer 11 made of the conductive paste is formed are prepared. The thickness of the internal electrode layer 11 made of a conductive paste is preferably 1 μm or less after drying from the viewpoint of the request for thinning of the internal electrode layer 11.

  Next, the ceramic green sheets were peeled off from the support film, and the dielectric layers 12 made of the ceramic green sheets and the internal electrode layers 11 made of the conductive paste formed on one side of the ceramic green sheets were alternately arranged. Thereafter, the laminate 10 is obtained by heating and pressure treatment. In addition, it is good also as a structure which arrange | positions the ceramic green sheet for protection which is not apply | coating the electroconductive paste on both surfaces of the laminated body 10.

Next, the laminated body is cut into a predetermined size to form a green chip, and then the green chip is subjected to a binder removal treatment and fired in a reducing atmosphere to produce a laminated ceramic sintered body. In addition, it is preferable that the atmosphere in the binder removal process be air or N ₂ gas atmosphere. The temperature at the time of debinding treatment is, for example, 200 ° C. or more and 400 ° C. or less. Moreover, it is preferable to make holding time of the said temperature into 0.5 to 24 hours at the time of performing a binder removal process. The firing is performed in a reducing atmosphere to suppress oxidation of the metal used in the internal electrode layer, and the temperature at which the laminate is fired is, for example, 1000 ° C. or more and 1350 ° C. or less. The holding time of temperature at the time of performing is 0.5 hours or more and 8 hours or less, for example.

  By firing the green chip, the organic binder in the green sheet is completely removed, and the ceramic raw material powder is fired to form the dielectric layer 12 made of ceramic. Further, the organic vehicle in the internal electrode layer 11 is removed, and the nickel powder or the alloy powder containing nickel as a main component is sintered or melted to form an internal electrode, whereby the dielectric layer 12 and the internal electrode are formed. A laminated ceramic fired body in which a plurality of layers 11 and a plurality of layers 11 are alternately stacked is formed. Note that from the viewpoint of incorporating oxygen into the inside of the dielectric layer to improve the reliability and suppressing reoxidation of the internal electrodes, the laminated ceramic fired body after firing may be subjected to an annealing treatment.

  The laminated ceramic capacitor 1 is manufactured by providing the pair of external electrodes 20 to the manufactured laminated ceramic fired body. For example, the external electrode 20 includes the external electrode layer 21 and the 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, copper, nickel, or these alloys can be used suitably, for example. In addition, electronic components other than multilayer ceramic capacitors can also be used.

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

[Evaluation method]
(Viscosity of conductive paste)
The viscosity after preparation of the conductive paste, by using a rheometer, shear rate ^{100 sec} -1, measured under the conditions of 10000 sec ^-1.

(Dispersivity of conductive paste)
The dispersibility of the conductive paste was evaluated by the following method.
The sample is printed (GAP thickness = 5 μm) and dried on a glass substrate (2 inch). Drying was performed in a belt furnace at a maximum temperature of 120 to 150 ° C. in the air. The dried film (2 cm × 2 cm, thickness 3 μm) obtained after drying is irradiated with light (backlight) from the back side of the glass substrate using an optical microscope, × 100 (eyepiece, objective; 10 times each) It observed and confirmed the presence or absence of a lump. When no lump is observed, the dispersibility of the paste is good, and when one or more lumps are observed, it can be judged that the dispersibility of the paste is poor.

[Material used]
(Conductive powder)
Ni powder (average particle diameter 0.3 μm) was used as the conductive powder.

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

(Binder resin)
As a binder resin, polyvinyl butyral resin (PVB) and ethyl cellulose (EC) were used.

(Dispersant)
(1) as a molecular weight of 5000 or less of amino acid-based dispersing agent, in the general formula _(1), acid dispersant represented by _{R 1 = C 17 H 33 (} A), an acid represented by R _{1 = C} 11 _{H 23} The system dispersant (B) was used.

(2) Rosinamine (C), polyethylene glycol laurylamine (D), and oleylamine (E) were used as the base dispersant.
(3) A phosphoric acid polyester (F) was used as a phosphoric acid based dispersant.

(Organic solvent)
Propylene glycol monobutyl ether (PNB), mineral spirits (MA) and terpineol (TPO) were used as organic solvents.

Example 1
25 parts by mass of ceramic powder, 2 parts by mass of amino acid-based dispersant (A) as a dispersant, 2 parts by mass of PVB as a binder resin, 4 parts by mass of EC, and 100 parts by mass of Ni powder as conductive powder A conductive paste was prepared by mixing 41 parts by mass of PNB (acetal solvent) and 27 parts by mass of MS as a solvent. The viscosity of the produced conductive paste and the dispersibility of the paste were evaluated by the above method. The content of the dispersant and the like of the conductive paste is shown in Table 1, and the evaluation results of the viscosity and dispersibility of the conductive paste are shown in Table 2.

Example 2
A conductive paste was prepared and evaluated in the same manner as in Example 1 except that 1.5 parts by mass of the amino acid based dispersing agent (A) was used as the dispersing agent. The content of the dispersant and the like of the conductive paste is shown in Table 1, and the evaluation results of the viscosity and dispersibility of the conductive paste are shown in Table 2.

[Example 3]
A conductive paste was prepared and evaluated in the same manner as in Example 1 except that 0.8 part by mass of the amino acid based dispersing agent (A) was used as the dispersing agent. The content of the dispersant and the like of the conductive paste is shown in Table 1, and the evaluation results of the viscosity and dispersibility of the conductive paste are shown in Table 2.

Example 4
A conductive paste was prepared and evaluated in the same manner as in Example 1 except that 0.05 part by mass of the amino acid based dispersing agent (A) was used as the dispersing agent. The content of the dispersant and the like of the conductive paste is shown in Table 1, and the evaluation results of the viscosity and dispersibility of the conductive paste are shown in Table 2.

[Example 5]
A conductive paste was prepared and evaluated in the same manner as in Example 1 except that 0.01 part by mass of the amino acid based dispersing agent (A) was used as the dispersing agent. The content of the dispersant and the like of the conductive paste is shown in Table 1, and the evaluation results of the viscosity and dispersibility of the conductive paste are shown in Table 2.

[Example 6]
A conductive paste was prepared and evaluated in the same manner as in Example 1 except that 0.8 parts by mass of the amino acid based dispersing agent (A) and 0.2 parts by mass of the rosin amine (C) were used as the dispersing agent. The content of the dispersant and the like of the conductive paste is shown in Table 1, and the evaluation results of the viscosity and dispersibility of the conductive paste are shown in Table 2.

[Example 7]
A conductive paste was prepared and evaluated in the same manner as in Example 1 except that 0.8 parts by mass of the amino acid based dispersing agent (A) and 0.2 parts by mass of polyethylene glycol laurylamine (D) were used as the dispersing agent. did. The content of the dispersant and the like of the conductive paste is shown in Table 1, and the evaluation results of the viscosity and dispersibility of the conductive paste are shown in Table 2.

[Example 8]
A conductive paste was prepared and evaluated in the same manner as in Example 1 except that 0.8 parts by mass of the amino acid based dispersing agent (A) and 0.2 parts by mass of oleylamine (E) were used as the dispersing agent. The content of the dispersant and the like of the conductive paste is shown in Table 1, and the evaluation results of the viscosity and dispersibility of the conductive paste are shown in Table 2.

[Example 9]
A conductive paste was produced and evaluated in the same manner as in Example 3 except that only 6 parts by mass of PVB was used as a binder resin. The content of the dispersant and the like of the conductive paste is shown in Table 1, and the evaluation results of the viscosity and dispersibility of the conductive paste are shown in Table 2.

[Example 10]
A conductive paste was prepared and evaluated in the same manner as in Example 3 except that 50 parts by mass of PNB and 18 parts by mass of MS were used as the organic solvent. The content of the dispersant and the like of the conductive paste is shown in Table 1, and the evaluation results of the viscosity and dispersibility of the conductive paste are shown in Table 2.

[Example 11]
A conductive paste was prepared and evaluated in the same manner as in Example 1 except that 0.8 parts by mass of the amino acid based dispersing agent (B) was used as the dispersing agent. The content of the dispersant and the like of the conductive paste is shown in Table 1, and the evaluation results of the viscosity and dispersibility of the conductive paste are shown in Table 2.

[Example 12]
A conductive paste was prepared and evaluated in the same manner as in Example 1 except that 0.8 parts by mass of the amino acid based dispersing agent (B) and 0.2 parts by mass of the rosin amine (C) were used as the dispersing agent. The content of the dispersant and the like of the conductive paste is shown in Table 1, and the evaluation results of the viscosity and dispersibility of the conductive paste are shown in Table 2.

Comparative Example 1
A conductive paste was produced and evaluated in the same manner as in Example 1 except that 0.8 parts by mass of phosphoric acid based dispersing agent (F) was used as a dispersing agent. The content of the dispersant and the like of the conductive paste is shown in Table 1, and the evaluation results of the viscosity and dispersibility of the conductive paste are shown in Table 2.

Comparative Example 2
A conductive paste is prepared in the same manner as in Example 1 except that 0.8 parts by mass of the phosphoric acid based dispersing agent (F) and 0.2 parts by mass of the basic dispersing agent (C) are used as the dispersing agent. evaluated. The content of the dispersant and the like of the conductive paste is shown in Table 1, and the evaluation results of the viscosity and dispersibility of the conductive paste are shown in Table 2.

Comparative Example 3
A conductive paste was prepared and evaluated in the same manner as in Example 1 except that only 0.8 parts by mass of the basic dispersant (C) was used as the dispersant. The content of the dispersant and the like of the conductive paste is shown in Table 1, and the evaluation results of the viscosity and dispersibility of the conductive paste are shown in Table 2.

Comparative Example 4
A conductive paste was prepared and evaluated in the same manner as in Example 3 except that only terpineol (TPO) was used as the organic solvent. The content of the dispersant and the like of the conductive paste is shown in Table 1, and the evaluation results of the viscosity and dispersibility of the conductive paste are shown in Table 2.
Comparative Example 5
A conductive paste was produced and evaluated in the same manner as in Example 3 except that only EC was used as a binder resin. The content of the dispersant and the like of the conductive paste is shown in Table 1, and the evaluation results of the viscosity and dispersibility of the conductive paste are shown in Table 2.
Comparative Example 6
A conductive paste was prepared and evaluated in the same manner as in Example 3 except that only EC was used as a binder resin, and only terpineol (TPO) was used as an organic solvent. The content of the dispersant and the like of the conductive paste is shown in Table 1, and the evaluation results of the viscosity and dispersibility of the conductive paste are shown in Table 2.

(Evaluation results)
Conductive paste examples, the viscosity of the shear rate 100 sec ^-1 is 0.44~0.79Pa · S, the viscosity of the shear rate 10000 sec ^-1 is 0.13~0.18Pa · S, gravure printing The viscosity was suitable for Moreover, in the conductive paste of this example, no lumps were observed on the surface of the dried film after printing, and it was shown that the dispersibility of the paste was excellent.

  On the other hand, in the conductive pastes of Comparative Examples 1 and 2 containing a phosphoric acid based dispersing agent instead of the amino acid based dispersing agent, lumps are observed on the surface of the dried film after printing, and the dispersibility of the paste is poor. Indicated. Further, Comparative Example 3 in which the dispersing agent does not contain an acid based dispersing agent and only the basic dispersing agent, Comparative Example 4 in which the organic solvent is out of the scope of the present invention, and Comparative Example 5 in which the binder resin is out of the scope of the present invention In the conductive paste of Comparative Example 6 in which the organic solvent and the binder resin are out of the range of the present invention, a viscosity suitable for gravure printing could not be obtained. Therefore, the surface properties after printing were roughened, and the lumps were not observed because they were not sufficiently smooth.

  The conductive paste of the present invention has a viscosity suitable for gravure printing, and the dispersibility of the paste is good. Therefore, the conductive paste of the present invention can be suitably used as a raw material for an internal electrode of a multilayer ceramic capacitor which is a chip component of an electronic device such as a mobile phone or a digital device, in particular. It can be suitably used as a paste.

Reference Signs List 1 laminated ceramic capacitor 10 ceramic laminated body 11 internal electrode layer 12 dielectric layer 20 external electrode 21 external electrode layer 22 plated layer

Claims (15)

A conductive paste comprising a conductive powder, a dispersant, a binder resin and an organic solvent,
The dispersant includes an amino acid dispersant having a molecular weight of 5,000 or less,
The binder resin contains an acetal resin,
The organic solvent includes glycol ether solvents.
Conductive paste characterized by The said amino acid type dispersing agent is shown by following General formula (1), The electroconductive paste of Claim 1 or 2 characterized by the above-mentioned.

However, in the general formula (1), R ₁ is a linear alkyl group having 10 to 20 carbon atoms or a linear alkenyl group having 10 to 20 carbon atoms.   The conductive paste according to claim 1 or 2, wherein the amino acid based dispersant is contained in an amount of 0.01 parts by mass or more and 2 parts by mass or less with respect to 100 parts by mass of the conductive powder.   The conductive paste according to any one of claims 1 to 3, wherein the content of the glycol ether-based solvent is 30 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the conductive powder.   The conductive paste according to any one of claims 1 to 4, wherein the dispersing agent further contains a basic dispersing agent.   The conductive paste according to any one of claims 1 to 5, wherein the dispersant is contained in an amount of 0.01 parts by mass or more and 2 parts by mass or less with respect to 100 parts by mass of the conductive powder. .   The said electroconductive powder contains Ni, Pd, Pt, Au, Ag, Cu, and at least 1 sort (s) of metal powder chosen from these alloys, The said any one of the Claims 1-6 characterized by the above-mentioned. Conductive paste.   The conductive paste according to any one of claims 1 to 7, wherein the conductive powder has an average particle diameter of 0.05 μm or more and 1.0 μm or less.   The conductive paste according to any one of claims 1 to 8, which contains a ceramic powder.   The conductive paste according to claim 9, wherein the ceramic powder comprises a perovskite oxide.   The conductive paste according to claim 9 or 10, wherein the ceramic powder has an average particle diameter of 0.01 μm or more and 0.5 μm or less.   The conductive paste according to any one of claims 1 to 11, which is for an internal electrode of a laminated ceramic component. Viscosity at shear rate 100 sec ^-1 is not higher than 0.8 Pa · S, any one of claims 1 to 12, the viscosity at shear rate 10000 sec ^-1 is equal to or less than 0.18Pa · S The conductive paste as described in.   A method of manufacturing an electronic component, comprising the conductive paste according to any one of claims 1 to 13. At least a laminated body in which a dielectric layer and an internal electrode are laminated,
The method for manufacturing a multilayer ceramic capacitor, wherein the internal electrode is formed using the conductive paste according to any one of claims 1 to 13.

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