WO2017150438A1 - Electrically conductive paste, electronic component, and laminated ceramic capacitor - Google Patents

Abstract

Provided is an electrically conductive paste, etc., which has exceptionally good adhesive strength. Provided is, inter alia, an electrically conductive paste containing an electrically conductive powder, a ceramic powder, a dispersant, a binder resin, and an organic solvent, wherein the dispersant includes an acid-based dispersant having a molecular weight of 500 or less, and the acid-based dispersant has a branched hydrocarbon group having at least one branched chain.

Description

Conductive paste, electronic components and multilayer ceramic capacitors

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

As electronic devices such as mobile phones and digital devices become smaller and have higher performance, electronic components including multilayer ceramic capacitors are also required to be smaller and have higher capacities. Multilayer ceramic capacitors have a structure in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately stacked. By reducing the thickness of these dielectric layers and internal electrode layers, the size and capacity can be reduced. Can be planned.

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

The conductive paste used for forming the internal electrode layer has a problem that the viscosity tends to increase with time. For this reason, at the beginning of printing, it can be formed on the ceramic green sheet with a desired viscosity with a predetermined thickness. However, after the predetermined time has elapsed, the viscosity increases, and the same thickness may not be formed under the initial printing conditions.

Therefore, attempts have been made to improve the time-dependent viscosity characteristics of the conductive paste. For example, it has been reported that the viscosity characteristics are improved by selecting the kind of binder resin or organic solvent in the conductive paste, the blending ratio, and the like. For example, Patent Document 1 describes a conductive paste that does not cause sheet attack and has little change over time by combining an organic vehicle containing a hydrophobic ethylhydroxyethylcellulose derivative as a binder resin with a specific organic solvent.

Further, in Patent Document 2, the conductive powder and the organic vehicle are contained under conditions used in combination with a ceramic green sheet having a thickness of 5 μm or less containing butyral resin, and the solvent in the organic vehicle A conductive paste containing nyl acetate as a main component and having little change in viscosity over time is described.

On the other hand, the conductive paste used for the internal electrode may contain a dispersant in order to improve the dispersibility of the conductive powder or the like (for example, Patent Document 3). As the internal electrode layer becomes thinner in recent years, the conductive powder also tends to have a smaller particle size. When the particle size of the conductive powder is small, the specific surface area of the particle surface increases, so that the surface activity of the conductive powder (metal powder) is increased, which may result in a decrease in dispersibility and a decrease in viscosity characteristics. .

For example, Patent Document 4 discloses a conductive paste containing at least a metal component, an oxide, a dispersant, and a binder resin, and the metal component has a surface composition of Ni having a specific composition ratio. The conductive paste is powder, the acid point amount of the dispersant is 500 to 2000 μmol / g, and the acid point amount of the binder resin is 15 to 100 μmol / g, and the conductive paste has good dispersibility and viscosity stability. It is described.

JP 2011-159393 A JP 2006-12690 A JP 2012-77372 A JP-A-2015-216244

Patent Documents 1 to 4 describe conductive pastes with little change in viscosity over time. However, as the thickening of the conductive paste over time becomes more problematic as the internal electrode layer becomes thinner, the conductive properties with improved viscosity characteristics have become available as the electrode pattern has become thinner in recent years. A paste is sought.

In view of such circumstances, an object of the present invention is to provide a conductive paste that has very little change in viscosity over time and is superior in viscosity stability.

In the first aspect of the present invention, a conductive paste containing conductive powder, ceramic powder, a dispersant, a binder resin and an organic solvent, the dispersant containing an acid-based dispersant having a molecular weight of 500 or less, an acid The conductive dispersant is provided with a conductive paste having a branched hydrocarbon group having one or more branched chains.

The acid dispersant is preferably an acid dispersant having a carboxyl group. The acid dispersant is preferably represented by the following general formula (1).

　ただし、上記一般式（１）中、Ｒ_１は、炭素数１０以上２０以下の分岐アルキル基又は炭素数１０以上２０以下の分岐アルケニル基である。

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

Further, the acid-based dispersant is preferably contained in an amount of 0.01 parts by mass or more and 3 parts by mass or less with respect to 100 parts by mass of the conductive powder. Further, it is preferable that the dispersant further contains a base dispersant. The dispersant is preferably contained in an amount of 0.01 parts by mass or more and 3 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. The conductive powder preferably has an average particle size of 0.05 μm or more and 1.0 μm or less. The ceramic powder preferably contains a perovskite oxide. The ceramic powder preferably has an average particle size of 0.01 μm or more and 0.5 μm or less. The binder resin preferably contains at least one of a cellulose resin, an acrylic resin, and a butyral resin. When the viscosity immediately after production of the conductive paste is 100%, the viscosity after standing for 60 days is preferably 80% or more and 120% or less. Moreover, it is preferable that the said electrically conductive paste is for internal electrodes of a multilayer ceramic component.

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

In a third aspect of the present invention, there is provided a multilayer ceramic capacitor having 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.

The conductive paste of the present invention has very little change in viscosity over time and is excellent in viscosity stability. In addition, the electrode pattern of an electronic component such as a multilayer ceramic capacitor formed using the conductive paste of the present invention has excellent printability of the conductive paste even when forming a thinned electrode, and has a uniform width and a high accuracy. It has a thickness.

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

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

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

The average particle size of the conductive powder is preferably 0.05 μm or more and 1.0 μm or less, 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 an internal electrode of a thin-film laminated ceramic capacitor, and for example, the smoothness of the dry film and the dry film density are improved. The average particle diameter is a value obtained from observation with a scanning electron microscope (SEM), and refers to a particle diameter having an integrated value of 50% in the 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 with respect to the total amount of the conductive paste. When content of electroconductive powder is the said range, it is excellent in electroconductivity and dispersibility.

(Ceramic powder)
The ceramic powder is not particularly limited. For example, in the case of a paste for internal electrodes of a multilayer ceramic capacitor, a known ceramic powder is appropriately selected depending on the type of multilayer ceramic capacitor to be applied. Examples of the ceramic powder include perovskite oxides containing Ba and Ti, and preferably barium titanate (BaTiO ₃ ). In addition, 1 type may be used for ceramic powder and 2 or more types may be used for it.

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

Examples of the ceramic powder include a perovskite oxide ferroelectric ceramic powder in which Ba atoms and Ti atoms of barium titanate (BaTiO ₃ ) are substituted with other atoms, for example, Sn, Pb, Zr, and the like. You can also

As the ceramic powder in the internal electrode paste, a powder having the same composition as that of the dielectric ceramic powder constituting the green sheet of the multilayer ceramic capacitor may be used. Thereby, the generation of cracks due to the shrinkage mismatch at the interface between the dielectric layer and the internal electrode layer in the sintering process is suppressed. Examples of such ceramic powder include, besides the perovskite oxide containing Ba and Ti, ZnO, ferrite, PZT, BaO, Al ₂ O ₃ , Bi ₂ O ₃ , R (rare earth element) ₂ O _3. , TiO ₂ , Nd ₂ O ₃ and other oxides.

The average particle size of the ceramic powder is, for example, 0.01 μm or more and 0.5 μm or less, and preferably 0.01 μm or more and 0.3 μm or less. When the average particle diameter of the ceramic powder is within the above range, a sufficiently thin and thin uniform internal electrode can be formed when used as an internal electrode paste. The average particle diameter is a value obtained from observation with a scanning electron microscope (SEM), and refers to a particle diameter having an integrated value of 50% in the particle size distribution.

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

The content of the ceramic powder is preferably 1% by mass or more and 20% by mass or less, and more preferably 3% by mass or more and 20% by mass or less, with respect to the total amount of the conductive paste. When content of electroconductive powder is the said range, it is excellent in electroconductivity and dispersibility.

(Binder resin)
It does not specifically limit as binder resin, A well-known resin can be used. Examples of the binder resin include cellulose resins such as methyl cellulose, ethyl cellulose, ethyl hydroxyethyl cellulose, and nitrocellulose, butyral resins such as acrylic resins and polyvinyl butyral. Among these, it is preferable to contain ethyl cellulose from the viewpoints of solubility in a solvent and combustion decomposability. Moreover, when using as a paste for internal electrodes, you may use a butyral resin from a viewpoint of improving the adhesive strength with a green sheet, or you may use it by a butyral resin single-piece | unit. One type of binder resin may be used, or two or more types may be used. The molecular weight of the binder resin is, for example, about 20,000 to 200,000.

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

The content of the binder resin is preferably 0.5% by mass or more and 10% by mass or less, and more preferably 1% by mass or more and 6% by mass or less 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)
It does not specifically limit as an organic solvent, The well-known organic solvent which can melt | dissolve the said binder resin can be used. Examples of organic solvents include dihydroterpinyl acetate, isobornyl acetate, isobornyl propionate, isobornyl butyrate, isobornyl isobutyrate, ethylene glycol monobutyl ether acetate, dipropylene glycol methyl ether acetate, and the like. And terpene solvents such as terpineol and dihydroterpineol, saturated aliphatic hydrocarbon solvents such as tridecane, nonane, and cyclohexane. In addition, the organic solvent may use 1 type and may use 2 or more types.

The organic solvent includes, for example, at least one acetate solvent (A) selected from dihydroterpinyl acetate, isobornyl acetate, isobornyl propionate, isobornyl butyrate and isobornyl isobutyrate. But you can. Among these, isobornyl acetate is more preferable. When the organic solvent contains the acetate solvent (A) as a main component, the acetate solvent (A) is preferably contained in an amount of 90% by mass or more and 100% by mass or less, more preferably 100% by mass with respect to the entire organic solvent. Contained.

The organic solvent may contain, 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. 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 mass% or more and 90 mass% or less of the acetate solvent (A) with respect to the entire organic solvent. More preferably, the content is 60% by mass or more and 80% by mass or less. In the case of the above mixed liquid, 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) with respect to 100% by mass of the whole organic solvent. .

The content of the organic solvent is preferably 40 parts by mass or more and 90 parts by mass or less, and more preferably 45 parts by mass or more and 85 parts by mass or less with respect to 100 parts by mass of the conductive powder. When the content of the organic solvent is within the above range, the conductivity and dispersibility are excellent.

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

(Dispersant)
The electrically conductive paste of this embodiment contains the acid type dispersing agent which has a branched hydrocarbon group. The branched hydrocarbon group of the acid dispersant has one or more branched chains. As a result of examining various dispersants for the dispersant used in the conductive paste, the present inventor has included an acid-based dispersant having a branched hydrocarbon group. It has been found that the change in viscosity over time is greatly suppressed.

Further, the acid dispersant preferably has a carboxyl group. By using such a dispersant, the reason is not limited, but the carboxyl group is adsorbed on the surface of the conductive powder, etc., neutralizing the surface potential, or inactivating the hydrogen bonding site, and the site other than the carboxyl group It is surmised that the specific three-dimensional structure as described above can effectively suppress aggregation of the conductive powder and the like, and can further improve the stability of the paste viscosity. The acid dispersant may be a compound having an amide bond.

In addition, the acid dispersant preferably has a low molecular weight. Here, the low molecular weight acid-based dispersant refers to an acidic dispersant having a molecular weight of 500 or less, for example. On the other hand, the lower limit of the molecular weight is preferably 100 or more, more preferably 200 or more. In addition, the said dispersing agent may use 1 type and may use 2 or more types.

For example, the hydrocarbon group in the acid-based dispersant may include one branched chain with respect to the main chain, or may include two or more branched chains. The number of branched chains is preferably 1 or more and 3 or less. Further, the number of branched chains may be 4 or more.

The acid dispersant may be a mixture containing a plurality of acid dispersants having branched hydrocarbon groups having different branch positions. In the case of a mixture containing a plurality of acid dispersants, the paste viscosity stability over time can be further improved.

Further, the acid-based dispersant may be an acid-based dispersant having a complicated branched structure (for example, two or more branched chains). In the case of an acid-based dispersant having such a complicated branched structure, the paste viscosity stability over time can be further improved.

Examples of the acid dispersant as described above include an acid dispersant represented by the following general formula (1).

In the above general formula (1), R ₁ represents a branched alkyl group having 10 to 20 carbon atoms (or a branched 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 branched alkyl group or a branched alkenyl group having a carbon double bond, and is preferably a branched alkyl group.

The presence or absence of a branched chain can be confirmed by, for example, the content of the methyl group (—CH ₃ ) at the terminal of the hydrocarbon group calculated based on the ¹³ C-NMR or ¹ H-NMR spectrum. For example, when the acid dispersant represented by the general formula (1) is a mixture, or when the structure of R _{1 in} the general formula (1) is a complicated structure having a plurality of branches, There may be a case where a clear peak indicating the R ₁ portion is not detected. Even in this case, a peak indicating a terminal methyl group (—CH ₃ ) is clearly observed.

The acid-based dispersant is preferably contained in an amount of 0.01 to 3 parts by weight, more preferably 0.05 to 2 parts by weight, with respect to 100 parts by weight of the conductive powder. More preferably 0.05 to 1 part by mass is contained. When the content of the acid dispersant is in the above range, the dispersibility of the conductive powder in the conductive paste and the stability of the viscosity of the conductive paste over time are excellent.

In particular, from the viewpoint of further improving the stability of the viscosity over time, the content of the acid dispersant is preferably 0.5 parts by mass or more and 2 parts by mass or less with respect to 100 parts by mass of the conductive powder. Yes, more preferably 1 part by mass or more and 2 parts by mass or less. Further, from the viewpoint of improving conductivity and suppressing sheet attack, the content of the acid dispersant is preferably small, and the upper limit of the content of the acid dispersant is, for example, 1 part by mass or less. , Preferably it can be 0.5 mass part or less. In the conductive paste of this embodiment, for example, even when the acid-based dispersant is contained in an amount of 0.1 part by mass or more and 0.5 part by mass or less, the stability of the viscosity with time is sufficiently excellent.

The above acid dispersant is contained, for example, in an amount of 3% by mass or less with respect to the entire conductive paste. The upper limit of the content of the acid-based dispersant is preferably 2% by mass or less, more preferably 1.5% by mass or less, and further preferably 1% by mass or less. Although the minimum of content of an acid type dispersing agent is not specifically limited, For example, it is 0.01 mass% or more, Preferably it is 0.05 mass% or more. When the content of the acid dispersant is in the above range, the change in viscosity with time is more stably suppressed. In addition, some organic solvents, when used in combination with a binder resin, cause sheet attack and green sheet peeling failure, but these problems are caused by containing a specific amount of the above-mentioned acid-based dispersant. Can be suppressed.

The above-mentioned acid-based dispersant can be selected from, for example, commercially available products that satisfy the above characteristics. Moreover, you may manufacture an acid type dispersing agent so that the said characteristic may be satisfy | filled using a conventionally well-known manufacturing method.

The conductive paste may contain a dispersant other than the above acid-based dispersion, for example, an acid-based dispersant having a linear hydrocarbon group. Examples of the acid dispersant other than the above-mentioned acid dispersion include acid dispersants such as 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 an unsaturated carboxylic acid or a saturated carboxylic acid, and is not particularly limited. However, stearic acid, oleic acid, myristic acid, palmitic acid, linoleic acid, lauric acid, linolenic acid and the like having 11 or more carbon atoms. Can be mentioned. Of these, oleic acid or stearic acid is preferred.

Other acid dispersants are not particularly limited, and are alkyl monoamine salt types represented by monoalkylamine salts, alkyldiamine salt types represented by N-alkyl (C14 to C18) propylenediamine dioleate. Alkyltrimethylammonium salt type represented by alkyltrimethylammonium chloride, Alkyldimethylbenzylammonium salt type represented by coconut alkyldimethylbenzylammonium chloride, Quaternary ammonium salt type represented by alkyl dipolyoxyethylenemethylammonium chloride , Alkylpyridinium salt type, tertiary amine type typified by dimethylstearylamine, polyoxyethylene alkylamine type typified by polyoxypropylene / polyoxyethylene alkylamine, N, ', N'-tris (2-hydroxyethyl) -N-alkyl (C14-18) 1,3-diaminopropane, and other surfactants selected from oxyethylene addition forms of diamines, Of these, the alkyl monoamine salt type is preferred.

As the alkyl monoamine salt type, for example, oleoyl sarcosine, which is a compound of glycine and oleic acid, and an amide compound using a higher fatty acid such as stearic acid or lauric acid instead of oleic acid are preferable.

Further, the dispersant may include a dispersant other than the acid-based dispersant. Examples of the dispersant other than the acid dispersion include a base dispersant, a nonionic dispersant, and an amphoteric dispersant. These dispersants may be used alone or in combination of two or more.

Examples of the base dispersant include aliphatic amines such as laurylamine, rosinamine, cetylamine, myristylamine and stearylamine. When the conductive paste contains the above acid-based dispersant having a branched hydrocarbon group and a base-based dispersion, the conductive paste is more excellent in dispersibility and superior in viscosity stability over time.

The base dispersant may be contained in an amount of, for example, 0.2 parts by mass or more and 2.5 parts by mass or less, preferably 0.2 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of the conductive powder. May be. The base dispersant is contained in an amount of about 10 parts by mass to about 300 parts by mass, preferably 50 parts by mass or more and 150 parts by mass with respect to 100 parts by mass of the acid dispersant having the branched hydrocarbon group. be able to. When the base dispersion is contained in the above range, the viscosity stability over time of the paste is more excellent.

The base dispersant is contained, for example, in an amount of 0% by mass to 2.5% by mass, preferably 0% by mass to 1.0% by mass, and more preferably 0.1% by mass with respect to the entire conductive paste. It is contained in an amount of 1.0% by mass or less, more preferably 0.1% by mass or more and 0.8% by mass or less. When the base dispersion is contained in the above range, the viscosity stability over time of the paste is more excellent.

The dispersant other than the acid-based dispersant may be contained in an amount of, for example, 0.2 parts by mass or more and 2.5 parts by mass or less with respect to 100 parts by mass of the conductive powder. Further, the dispersant other than the acid dispersant can be contained in an amount of, for example, about 50 parts by mass or more and 300 parts by mass with respect to 100 parts by mass of the acid dispersant. Moreover, as a whole dispersing agent, it is preferable to contain 0.01 mass part or more and 3 mass parts or less with respect to 100 mass parts of electroconductive powder.

The dispersant other than the acid-based dispersant is, for example, contained 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, based on the entire conductive paste. It is contained in an amount of 0.1% by mass or more and 1.0% by mass or less, more preferably 0.1% by mass or more and 0.8% by mass or less. When the dispersant other than the acid dispersant exceeds 1.0% by weight, not only the drying property of the conductive paste is deteriorated but also the sheet attack is not preferable.

(Conductive paste)
The electrically conductive paste of this embodiment can be manufactured by preparing each said component, stirring and kneading with a mixer. At that time, if a dispersant is applied to the surface of the conductive powder in advance, the conductive powder is sufficiently loosened without agglomeration, and the dispersant is spread over the surface, so that a uniform conductive paste is easily obtained. In addition, the binder resin is dissolved in an organic solvent for the vehicle to prepare an organic vehicle, and the conductive powder, the ceramic powder, the organic vehicle, and the dispersant are added to the organic solvent for the paste, and the mixture is stirred and kneaded with a mixer. A conductive paste may be produced.

In the organic solvent, the organic solvent for the vehicle is preferably the same as the organic solvent for the paste for adjusting the viscosity of the conductive paste in order to improve the familiarity of the organic vehicle. The content of the organic solvent for the vehicle is, for example, 5 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the conductive powder. The content of the organic solvent for the conductive paste is preferably 10% by mass or more and 40% by mass or less with respect to the total amount of the conductive paste.

The conductive paste has a viscosity after standing for 60 days determined by the following formula, for example, from 0% to 30%, preferably 25% or less, and more preferably 20% or less.
Formula: [viscosity after standing for 60 days−viscosity immediately after production) / viscosity immediately after production] × 100)

The conductive paste has a viscosity after standing for 60 days, for example, 70% or more and 130% or less, preferably 80% or more and 120% or less, assuming that the viscosity immediately after the production of the conductive paste is 100%. More preferably, they are 85% or more and 115% or less, More preferably, they are 90% or more and 110% or less.

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

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

[Electronic parts]
Hereinafter, embodiments of an electronic component and the like of the present invention will be described with reference to the drawings. In the drawings, they may be schematically expressed as appropriate, or may be expressed by changing the scale. Further, the positions and directions of the members will be 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 (up and down direction).

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

Hereinafter, a method for manufacturing a multilayer ceramic capacitor using the conductive paste will be described. First, an internal electrode layer 11 made of a conductive paste is formed on a dielectric layer 12 made of a ceramic green sheet by a printing method, and a plurality of dielectric layers having the internal electrode layer on the upper surface are laminated by pressure bonding. After obtaining the multilayer body 10, the multilayer body 10 is fired and integrated to produce a multilayer ceramic fired body (not shown) that becomes a ceramic capacitor body. Thereafter, the multilayer ceramic capacitor 1 is manufactured by forming a pair of external electrodes at both ends of the ceramic capacitor body. This will be described in more detail below.

First, prepare a ceramic green sheet, which is an unfired ceramic sheet. As this ceramic green sheet, for example, a dielectric layer paste obtained by adding an organic binder such as polyvinyl butyral and a solvent such as terpineol to a predetermined ceramic raw material powder such as barium titanate, a PET film or the like. Examples thereof include a sheet formed on a support film and dried to remove the solvent. The thickness of the dielectric layer made 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 the demand for downsizing of the multilayer ceramic capacitor.

Next, a plurality of sheets are prepared by printing and applying the above-described conductive paste on one surface of the ceramic green sheet by a known method such as a screen printing method to form the internal electrode layer 11 made of the conductive paste. To do. The thickness of the internal electrode layer 11 made of a conductive paste is preferably set to 1 μm or less after drying from the viewpoint of a request for thinning 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 surface thereof were laminated alternately. Then, the laminated body 10 is obtained by heating and pressurizing treatment. In addition, it is good also as a structure which further arrange | positions the ceramic green sheet for protection which has not apply | coated the electrically conductive paste on both surfaces of the laminated body 10. FIG.

Next, after the laminated body is cut to a predetermined size to form a green chip, the green chip is subjected to a binder removal treatment and fired in a reducing atmosphere to produce a laminated ceramic fired body. The atmosphere in the debinding process is preferably air or N ₂ gas atmosphere. The temperature at which the binder removal treatment is performed is, for example, 200 ° C. or higher and 400 ° C. or lower. Moreover, it is preferable that the holding time of the said temperature at the time of performing a binder removal process shall be 0.5 hours or more and 24 hours or less. The firing is performed in a reducing atmosphere in order to suppress oxidation of the metal used for the internal electrode layer, and the temperature when firing the laminate is, for example, 1000 ° C. or higher and 1350 ° C. or lower. The holding time of the temperature at the time of performing is 0.5 hour 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 ceramic dielectric layer 12. 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 and integrated to form an internal electrode. The dielectric layer 12 and the internal electrode A multilayer ceramic fired body in which a plurality of layers 11 are alternately stacked is formed. In addition, annealing may be performed on the fired multilayer ceramic fired body from the viewpoint of taking oxygen into the dielectric layer to improve reliability and suppressing reoxidation of the internal electrode.

Then, the multilayer ceramic capacitor 1 is manufactured by providing a pair of external electrodes 20 to the manufactured multilayer 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, copper, nickel, or these alloys can be used conveniently, for example. As the electronic component, an electronic component other than the multilayer ceramic capacitor can 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 methods]
(Change in viscosity of conductive paste)
Immediately after production of the conductive paste and after standing at room temperature (25 ° C.) for 60 days, the viscosity of each sample was measured by the following method, and the viscosity immediately after production was used as a reference (0%). The change in viscosity of the sample after standing was expressed as a percentage (%) ([viscosity after standing for 60 days−viscosity immediately after production) / viscosity immediately after production] × 100). The smaller the amount of change in the viscosity of the conductive paste, the better.
Viscosity of conductive paste: Measured using a Brookfield B-type viscometer at 10 rpm (shear rate = 4 sec ⁻¹ ).

[Materials used]
(Conductive powder)
As the conductive powder, Ni powder (particle size 0.3 μm) or Ni powder (particle size 0.2 μm) was used.

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

(Binder resin)
Ethyl cellulose was used as the binder resin.

(Dispersant)
Table 1 shows the dispersant used.
(1) An acid dispersant represented by the following general formula (1) (R ₁ = C ₁₇ H ₃₅ ) was used as the acid dispersant A having a branched hydrocarbon chain having a molecular weight of 500 or less (Table 1: No .1). The presence or absence of a branched chain was confirmed using ¹ H-NMR spectrum and Fourier transform infrared spectroscopy (FT-IR). From these results, the peak detected in the linear branched chain (linear hydrocarbon group) was not observed, but the peak indicating the terminal methyl group (—CH ₃ ) was observed, and R ¹ had one or more branches. Confirmed to have.

(2) As an acid dispersant having a linear hydrocarbon chain having a molecular weight of 500 or less, oleic acid (C ₁₈ H ₃₄ NO ₂ ), stearic acid (C ₁₈ H ₃₆ O ₂ ), behenic acid (C ₂₂ H ₄₄ O) _2), oleoyl sarcosine _{(C 21 H 39 NO 3)} , lauric acid _{(C 12 H 24 O 2)} , linoleic acid _{(C 18 H 32 O 2)} , use the palmitoleic acid _{(C 16 H} 30 _{O 2)} (Table 1: No. 2 to 8).
(3) Myristylamine, cetylamine, and stearylamine were used as the base dispersant (Table 1: No. 9 to 11).

(Organic solvent)
Turpineol was used as the organic solvent.

[Example 1]
For 100 parts by mass of Ni powder, which is a conductive powder, 5.3 parts by mass of ceramic powder, 0.1 parts by mass of acid dispersant A, 5 parts by mass of binder resin, and 49 parts by mass of organic solvent are mixed. Thus, a conductive paste was produced. The viscosity (60 days later) of the produced conductive paste was evaluated by the above method. The evaluation results of the amount of change in paste viscosity are shown in Table 2 together with the content of the acid dispersant with respect to 100 parts by mass of Ni powder.

[Example 2]
A conductive paste was prepared in the same manner as in Example 1 except that the content of the acid dispersant A was 0.5 parts by mass. The evaluation results of the amount of change in paste viscosity are shown in Table 2 together with the content of the acid dispersant with respect to 100 parts by mass of Ni powder.

[Example 3]
A conductive paste was prepared in the same manner as in Example 1 except that the content of the acid dispersant A was 1.0 part by mass. Table 2 shows the characteristics of the dispersant used and the evaluation results of the amount of change in paste viscosity, together with the content of the acid dispersant with respect to 100 parts by mass of the Ni powder.

[Example 4]
A conductive paste was produced in the same manner as in Example 1 except that the content of the acid dispersant A was 1.5 parts by mass. The evaluation results of the amount of change in paste viscosity are shown in Table 2 together with the content of the acid dispersant with respect to 100 parts by mass of Ni powder.

[Example 5]
A conductive paste was produced in the same manner as in Example 1 except that the content of the acid dispersant A was 2.0 parts by mass. The evaluation results of the amount of change in paste viscosity are shown in Table 2 together with the content of the acid dispersant with respect to 100 parts by mass of Ni powder.

[Comparative Example 1]
A conductive paste was prepared in the same manner as in Example 1, except that the acid dispersant was oleic acid (Table 1: No. 2, no hydrocarbon group branching). The evaluation results of the amount of change in paste viscosity are shown in Table 2 together with the content of the acid dispersant with respect to 100 parts by mass of Ni powder.

[Comparative Examples 2 to 4]
Comparative Example, except that the content of the acid dispersant (oleic acid) was 0.5 parts by mass (Comparative Example 2), 1 part by mass (Comparative Example 3), and 1.5 parts by mass (Comparative Example 4), respectively. A conductive paste was prepared as in 1. The evaluation results of the amount of change in paste viscosity are shown in Table 2 together with the content of the acid dispersant with respect to 100 parts by mass of Ni powder.

[Comparative Examples 5 to 10]
Acidic dispersants include stearic acid (Comparative Example 5), behenic acid (Comparative Example 6), oleoyl sarcosine (Comparative Example 7), lauric acid (Comparative Example 8), linoleic acid (Comparative Example 9), palmitoleic acid A conductive paste was produced in the same manner as in Example 1 except that (Comparative Example 10) was used. The evaluation results of the amount of change in paste viscosity are shown in Table 2 together with the content of the acid dispersant with respect to 100 parts by mass of Ni powder.

[Example 6]
11.6 parts by mass of ceramic powder and 0.6 parts by mass of dispersant (0.2 parts by mass of acid-based dispersant A, base) with respect to 100 parts by mass of Ni powder (particle size: 0.3 μm) as conductive powder A conductive paste was prepared by mixing 0.4 part by mass of a dispersant), 5 parts by mass of a binder resin, and 51 parts by mass of an organic solvent. In addition, myristylamine was used as the basic dispersant (Table 1: No. 9). The amount of change in viscosity (after 60 days) of the produced conductive paste was evaluated by the above method. The evaluation results of the paste viscosity are shown in Table 3 together with the particle size of the Ni powder and the contents of the dispersant and the ceramic powder. In addition, content (mass part) in Table 3 shows the quantity with respect to 100 mass parts of Ni powder.

[Example 7]
A conductive paste was prepared in the same manner as in Example 6 except that the content of the acid dispersant A was 0.5 parts by mass. The evaluation results of the paste viscosity are shown in Table 3 together with the particle size of the Ni powder and the contents of the dispersant and the ceramic powder. In addition, content (mass part) in Table 3 shows the quantity with respect to 100 mass parts of Ni powder.

[Example 8]
A conductive paste was prepared in the same manner as in Example 6 except that the content of the acid dispersant A was 2.0 parts by mass. The evaluation results of the paste viscosity are shown in Table 3 together with the particle size of the Ni powder and the contents of the dispersant and the ceramic powder. In addition, content (mass part) in Table 3 shows the quantity with respect to 100 mass parts of Ni powder.

[Example 9]
A conductive paste was produced in the same manner as in Example 7 except that the content of the ceramic powder was 5.3 parts by mass. The evaluation results of the paste viscosity are shown in Table 3 together with the particle size of the Ni powder and the contents of the dispersant and the ceramic powder. In addition, content (mass part) in Table 3 shows the quantity with respect to 100 mass parts of Ni powder.

[Examples 10 to 12]
Using Ni powder (particle size: 0.2 μm), the basic dispersant is myristylamine (Example 10), cetylamine (Example 11), stearylamine (Example 12), and the basic dispersant content is A conductive paste was produced in the same manner as in Example 9 except that the amount was 0.5 parts by weight. The evaluation results of the paste viscosity are shown in Table 3 together with the particle size of the Ni powder and the contents of the dispersant and the ceramic powder. In addition, content (mass part) in Table 3 shows the quantity with respect to 100 mass parts of Ni powder.

[Comparative Examples 11 to 12]
A conductive paste was prepared in the same manner as in Example 6 except that 0.3 parts by mass of oleic acid (Comparative Example 11) and 0.3 part by mass of stearic acid (Comparative Example 12) were used as the acid dispersant. . The evaluation results of the paste viscosity are shown in Table 3 together with the particle size of the Ni powder and the contents of the dispersant and the ceramic powder. In addition, content (mass part) in Table 3 shows the quantity with respect to 100 mass parts of Ni powder.

[Comparative Example 13]
A conductive paste was prepared in the same manner as in Example 11 except that oleic acid was used as the acid dispersant. The evaluation results of the paste viscosity are shown in Table 3 together with the particle size of the Ni powder and the contents of the dispersant and the ceramic powder. In addition, content (mass part) in Table 3 shows the quantity with respect to 100 mass parts of Ni powder.

[Comparative Example 14]
A conductive paste was produced in the same manner as in Example 12 except that stearic acid was used as the acid dispersant. The evaluation results of the paste viscosity are shown in Table 3 together with the particle size of the Ni powder and the contents of the dispersant and the ceramic powder. In addition, content (mass part) in Table 3 shows the quantity with respect to 100 mass parts of Ni powder.

(Evaluation results)
In the conductive paste of the example, the amount of change in paste viscosity after 60 days was small compared to the conductive paste of any comparative example. Therefore, it was shown that the conductive paste containing an acid dispersant having a branched hydrocarbon chain having a molecular weight of 500 or less has good viscosity stability.

The conductive paste of the present invention is extremely excellent in viscosity stability over time, and is particularly suitable for use as a raw material for internal electrodes of multilayer ceramic capacitors that are chip parts of electronic devices such as mobile phones and digital devices. Can do.

DESCRIPTION OF SYMBOLS 1 Multilayer ceramic capacitor 10 Ceramic multilayer body 11 Internal electrode layer 12 Dielectric layer 20 External electrode 21 External electrode layer 22 Plating layer

Claims (15)

A conductive paste containing conductive powder, ceramic powder, dispersant, binder resin and organic solvent,
The dispersant includes an acid dispersant having a molecular weight of 500 or less,
The acid-based dispersant has a branched hydrocarbon group having one or more branched chains.
A conductive paste characterized by that. The conductive paste according to claim 1, wherein the acid dispersant is an acid dispersant having a carboxyl group. The conductive paste according to claim 1 or 2, wherein the acid dispersant is represented by the following general formula (1).

However, in General Formula (1), R ₁ is a branched alkyl group having 10 to 20 carbon atoms or a branched alkenyl group having 10 to 20 carbon atoms. The conductive agent according to any one of claims 1 to 3, wherein the acid-based dispersant is contained in an amount of 0.01 parts by weight to 3 parts by weight with respect to 100 parts by weight of the conductive powder. paste. The conductive paste according to any one of claims 1 to 4, wherein the dispersant further contains a base dispersant. 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 weight to 3 parts by weight with respect to 100 parts by weight of the conductive powder. . The conductive powder includes at least one metal powder selected from Ni, Pd, Pt, Au, Ag, Cu, and alloys thereof, according to any one of claims 1 to 6. Conductive paste. The conductive paste according to any one of claims 1 to 7, wherein the conductive powder has an average particle size of 0.05 to 1.0 µm. The conductive paste according to any one of claims 1 to 8, wherein the ceramic powder contains a perovskite oxide. 10. The conductive paste according to claim 1, wherein the ceramic powder has an average particle size of 0.01 μm or more and 0.5 μm or less. The conductive paste according to any one of claims 1 to 10, wherein the binder resin contains at least one of a cellulose resin, an acrylic resin, and a butyral resin. The viscosity according to any one of claims 1 to 11, wherein when the viscosity immediately after production of the conductive paste is 100%, the viscosity after standing for 60 days is 80% or more and 120% or less. Conductive paste. The conductive paste according to any one of claims 1 to 12, which is used for an internal electrode of a multilayer ceramic component. An electronic component formed using the conductive paste according to any one of claims 1 to 13. Having at least a laminate in which a dielectric layer and an internal electrode are laminated,
14. A multilayer ceramic laminate, wherein the internal electrode is formed using the conductive paste according to any one of 1 to 13.

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