KR20210040290A - Conductive paste, electronic components and multilayer ceramic capacitors - Google Patents

Abstract

It has high dry film surface smoothness and high dry film density, has excellent dispersibility of the conductive powder, has high adhesion when forming a laminate, and has very little change in viscosity over time, and has more excellent viscosity stability. Provide a conductive paste.
As a conductive paste containing conductive powder, ceramic powder, dispersant, binder resin, and organic solvent, the dispersant is an amino acid-based dispersant represented by General Formula (1) described in the specification, and an amine-based dispersant represented by General Formula (2) described in the specification. A dispersant is contained, and the blending ratio of the amino acid-based dispersant and the amine-based dispersant (amino acid-based dispersant/amine-based dispersant) is in the range of 1/4 or more and 1/2 or less, by mass, and the sum of the amino acid-based dispersant and the amine-based dispersant The conductive paste content is 0.7 mass% or more and 1.2 mass% or less with respect to the whole conductive paste.

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.

Along with the miniaturization and high performance of electronic devices such as mobile phones and digital devices, miniaturization and higher capacity are also desired for electronic components including multilayer ceramic capacitors. The multilayer ceramic capacitor has a structure in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately stacked, and by making these dielectric layers and internal electrode layers thinner, miniaturization and high capacity can be achieved.

The multilayer ceramic capacitor is manufactured as follows, for example. First, on the surface of a green sheet containing a dielectric powder such as barium titanate (BaTiO ₃ ) and a binder resin, a conductive paste for internal electrodes is printed (coated) with a predetermined electrode pattern and dried to form a dried film. . Next, a laminate is formed in a state in which the dried film and the green sheet are alternately stacked so as to be superimposed, heated and compressed to be integrated. The laminate is cut, subjected to a deorganic binder treatment in an oxidizing atmosphere or an inert atmosphere, and then calcined to obtain a fired chip. Next, an external electrode paste is applied to both ends of the fired chip, and after firing, nickel plating or the like is applied to the surface of the external electrode to obtain a multilayer ceramic capacitor.

In general, a conductive paste used for forming an internal electrode layer contains a conductive powder, a ceramic powder, a binder resin, and an organic solvent. In addition, the conductive paste may contain a dispersant in order to improve the dispersibility of the conductive powder or the like. With the recent thinning of the internal electrode layer, the conductive powder also tends to be small-grained. When the particle diameter of the conductive powder is small, since the specific surface area of the particle surface becomes large, the surface activity of the conductive powder (metal powder) increases, resulting in a decrease in dispersibility and a decrease in viscosity characteristics in some cases.

Therefore, attempts have been made to improve the viscosity characteristics of the conductive paste over time. For example, in Patent Document 1, as a conductive paste containing at least a metal component, an oxide, a dispersant, and a binder resin, the metal component is Ni powder having a specific composition ratio in its surface composition, and the acid point amount of the dispersant ( The amount of content) is 500 to 2000 µmol/g, and the acid point amount of the binder resin is 15 to 100 µmol/g. And according to patent document 1, it is said that this electroconductive paste has favorable dispersibility and viscosity stability.

In addition, in Patent Document 2, as a conductive paste for internal electrodes composed of a conductive powder, a resin, an organic solvent, _{a ceramic powder mainly composed of TiBaO 3} , and an agglomeration inhibitor, the content of the agglomeration inhibitor is 0.1% by weight. The conductive paste for internal electrodes is described in an amount of 5% by weight or less, and wherein the aggregation inhibitor is a tertiary amine or a secondary amine represented by a specific structural formula. According to patent document 2, this conductive paste for internal electrodes suppresses aggregation of common material components, is excellent in long-term storage, and it is said that the thin film of a multilayer ceramic capacitor is possible.

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

Japanese Unexamined Patent Publication No. 2015-216244 Japanese Patent Application Laid-Open No. 2013-149457 Japanese Unexamined Patent Application Publication No. 2006-063441

However, with the recent thinning of the electrode pattern, further improvement of viscosity characteristics over time and improvement of the surface smoothness of the dried film after application are required.

In view of such a situation, the present invention has a high dry film surface smoothness and a high dry film density, has excellent dispersibility of conductive powder, has high adhesion when forming a laminate, and has a viscosity over time. It is an object of the present invention to provide an electrically conductive paste with very little change and more excellent viscosity stability.

In the first aspect of the present invention, as a conductive paste containing a conductive powder, a ceramic powder, a dispersant, a binder resin, and an organic solvent, the dispersant is an amino acid-based dispersant represented by the following general formula (1), and the following general formula (2). The amine-based dispersant represented by is contained, and the blending ratio of the amino acid-based dispersant and the amine-based dispersant (amino acid-based dispersant/amine-based dispersant) is in the range of 1/4 or more and 1/2 or less, by mass ratio, and the amino acid-based dispersant and amine-based dispersant The total content of is 0.7% by mass or more and 1.2% by mass or less with respect to the entire conductive paste, and a conductive paste is provided.

[Formula 1]

(However, in formula (1), R ₁ represents a chain hydrocarbon having 10 to 20 carbon atoms.)

[Formula 2]

(However, in formula (2), R ₂ represents an alkyl group having 8 to 16 carbon atoms, an alkenyl group, or an alkynyl group, R ₃ represents an oxyethylene group, an oxypropylene group, or a methylene group, and R ₄ represents an oxy An ethylene group or an oxypropylene group is represented, and R ₃ and R ₄ may be the same or different. The N atom in formula (2) and the _{O atom in R 3 and R 4} are not directly bonded, Y is a number from 0 to 2, and Z is a number from 1 to 2.)

Moreover, in General Formula (1), _{it is preferable that R<1>} represents a C10-20 linear hydrocarbon group. Further, it is preferable that the conductive powder contains at least one metal powder selected from Ni, Pd, Pt, Au, Ag, Cu, and alloys thereof. Moreover, it is preferable to contain the electroconductive powder 40 mass% or more and 60 mass% or less with respect to the whole electroconductive paste. Moreover, it is preferable that an average particle diameter of an electroconductive powder is 0.05 micrometers or more and 1.0 micrometers or less. Moreover, it is preferable that the ceramic powder contains a perovskite type oxide. Moreover, it is preferable that the average particle diameter of a ceramic powder is 0.01 micrometers or more and 0.5 micrometers or less. In addition, it is preferable that the binder resin contains at least one of a cellulose resin, an acrylic resin, and a butyral resin. Moreover, it is preferable that the said electroconductive paste is for internal electrodes of a multilayer ceramic capacitor.

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

In a third aspect of the present invention, there is provided a multilayer ceramic capacitor having a laminate in which an internal electrode formed using the conductive paste and a dielectric layer are laminated.

The conductive paste of the present invention has very little change in viscosity over time, is more excellent in viscosity stability, has excellent dispersibility of conductive powder, and has high surface smoothness and high dry film density in the dried film after application. . Further, the electrode pattern of an electronic component such as a multilayer ceramic capacitor formed by using the conductive paste of the present invention has excellent adhesion of the conductive paste even when forming a thin-film electrode, and has a uniform width and thickness with good precision.

Fig. 1A is a perspective view showing a multilayer ceramic capacitor according to the present embodiment, and Fig. 1B is a cross-sectional view of the multilayer ceramic capacitor according to the present embodiment.

The conductive paste of this embodiment contains a conductive powder, a 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 a metal powder can be used. For example, one or more kinds of powder selected from Ni, Pd, Pt, Au, Ag, Cu, and alloys thereof can be used. Among these, from the viewpoints of conductivity, corrosion resistance, and cost, Ni or a powder of an alloy thereof is preferred. As the Ni alloy, for example, an alloy of Ni with at least one element selected from the group consisting of Mn, Cr, Co, Al, Fe, Cu, Zn, Ag, Au, Pt, and Pd (Ni alloy) Can be used. The content of Ni 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 hundreds of ppm of S in order to suppress rapid gas generation due to partial thermal decomposition of the binder resin during the binder removal treatment.

The average particle diameter of the conductive powder is preferably 0.05 µm or more and 1.0 µm or less, and more preferably 0.1 µm or more and 0.5 µm or less. When the average particle diameter of the conductive powder is within the above range, it can be preferably used as a paste for internal electrodes of a thin multilayer ceramic capacitor, and, for example, the smoothness of the dried film and the dry film density are improved. The average particle diameter is a value obtained from observation with a scanning electron microscope (SEM), and is an average value obtained by measuring the particle diameter of each of a plurality of particles from an image observed with a magnification of 10,000 times by SEM.

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

(Ceramic powder)

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

As the ceramic powder, a ceramic powder containing barium titanate as a main component and an oxide as a secondary component may be used. Examples of the oxide include oxides of Mn, Cr, Si, Ca, Ba, Mg, V, W, Ta, and Nb, and one or more rare earth elements. As such a ceramic powder, for example, a ceramic powder of a perovskite oxide ferroelectric in which a Ba atom or Ti atom of _{barium titanate (BaTiO 3) is substituted with another atom, such as Sn, Pb, Zr, etc.} Can be lifted.

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. Thereby, the occurrence of cracks due to mismatch of shrinkage 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, for example, 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 Oxides. Moreover, one type may be used for ceramic powder, and two or more types may be used for it.

The average particle diameter of the ceramic powder is, for example, 0.01 µm or more and 0.5 µm or less, and preferably 0.01 µm or more and 0.3 µm or less. When the average particle diameter of the ceramic powder is within the above range, when used as an internal electrode paste, a sufficiently thin and uniform internal electrode can be formed. The average particle diameter is a value obtained from observation with a scanning electron microscope (SEM), and is an average value obtained by measuring the particle diameter of each of a plurality of particles from an image observed at a magnification of 50,000 times by SEM.

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 5% by mass or more and 20% by mass or less with respect to the total amount of the conductive paste. When the content of the ceramic powder is within the above range, it is excellent in conductivity and dispersibility.

(Binder resin)

The binder resin is not particularly limited, and a known resin can be used. Examples of the binder resin include cellulose resins such as methylcellulose, ethylcellulose, ethylhydroxyethylcellulose, and nitrocellulose, butyral resins such as acrylic resins and polyvinyl butyral. Among them, it is preferable to contain ethyl cellulose from the viewpoint of solubility in a solvent and decomposition by combustion. In the case of using as an internal electrode paste, from the viewpoint of improving the adhesive strength with the green sheet, a butyral resin may be contained, or a butyral resin may be used alone. One type of binder resin may be used, and two or more types may be used. As the binder resin, for example, a cellulose resin and a butyral resin can be used. Moreover, the molecular weight of a binder resin is about 20000-200,000, for example.

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 the content of the binder resin is within the above range, conductivity and dispersibility are excellent.

(Organic solvent)

The organic solvent is not particularly limited, and a known organic solvent capable of dissolving the binder resin can be used. As an organic solvent, for example, dihydroterpinyl acetate, isobornyl acetate, isobornyl propinate, isobornyl butyrate, isobornyl isobutylate, ethylene glycol monobutyl ether acetate, dipropylene glycol methyl Acetate-based solvents such as ether acetate, terpene-based solvents such as terpineol and dihydroterpineol, and hydrocarbon-based solvents such as tridecane, nonane, and cyclohexane. In addition, an organic solvent may be used 1 type and may use 2 or more types.

The content of the organic solvent is preferably 40 parts by mass or more and 100 parts by mass or less, and more preferably 65 parts by mass or more and 95 parts by mass or less with respect to 100 parts by mass of the conductive powder.

The content of the organic solvent is preferably 20% by mass or more and 60% by mass or less, and more preferably 35% by mass or more and 55% 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, it is excellent in conductivity and dispersibility.

(Dispersant)

The conductive paste of this embodiment contains a dispersant. The dispersant contains an amino acid-based dispersant (amino acid-based surfactant) represented by the general formula (1) and an amine-based dispersant represented by the general formula (2). Further, the dispersant may contain a dispersant other than the amino acid dispersant represented by the general formula (1) and the amine dispersant represented by the general formula (2).

The present inventors studied various dispersants for the dispersants used in the conductive paste, and as a result of combining the above two types of dispersants at a specific mixing ratio, the change in viscosity over time of the conductive paste is small, and the viscosity stability is very excellent. In addition, it was found that the electroconductive powder was excellent in dispersibility and had high surface smoothness and high dry film density in the dried film after application.

In addition, the present inventors combine the two types of dispersants at a specific blending ratio, and by setting the total content of the two types of dispersants to a specific amount, the viscosity stability and dispersibility of the conductive paste can be further improved. Together, it was found that the adhesion when forming the laminate was also excellent.

Although the details of this reason are unclear, it is thought that the amino group and carboxyl group present in the molecule|numerator of a dispersing agent act, such as coordination with the metal atom of a conductive powder. Hereinafter, the dispersant used in the present embodiment will be described.

The amino acid-based dispersant used in the present embodiment has an N-acylamino acid skeleton and a chain hydrocarbon group having 10 or more and 20 or less carbon atoms, as shown in the following general formula (1).

[Formula 3]

(However, in formula (1), R ₁ represents a chain hydrocarbon having 10 to 20 carbon atoms.)

In the formula (1), R ₁ represents a chain hydrocarbon group having 10 or more and 20 or less carbon atoms. R ₁ has preferably 15 or more and 20 or less carbon atoms. Further, the chain hydrocarbon group may be a linear hydrocarbon group or a branched hydrocarbon group. Moreover, the chain hydrocarbon group may be an alkyl group, an alkenyl group, or an alkynyl group. R ₁ is preferably a linear hydrocarbon group, more preferably a linear alkenyl group, and has a double bond.

The amino acid-based dispersant represented by the above formula (1) can be used by selecting, for example, a commercially available product that satisfies the above characteristics. Further, the amino acid-based dispersant may be prepared so as to satisfy the above characteristics by using a conventionally known production method.

The amine-based dispersant is a tertiary amine or a secondary amine, as represented by the following general formula (2), and has a structure in which an amine group and a 1 or 2 oxyalkylene group are bonded.

[Formula 4]

(However, in formula (2), R ₂ represents an alkyl group having 8 to 16 carbon atoms, an alkenyl group, or an alkynyl group, R ₃ represents an oxyethylene group, an oxypropylene group, or a methylene group, and R ₄ represents an oxy An ethylene group or an oxypropylene group is represented, and R ₃ and R ₄ may be the same or different, and the N atom in formula (2) and the _{O atom in R 3 and R 4} are not directly bonded. And Y is a number of 0-2, and Z is a number of 1-2.)

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

In the above formula (2), R ₃ represents an oxyethylene group, an oxypropylene group, or a methylene group, R ₄ represents an oxyethylene group or an oxypropylene group, and R ₃ and R ₄ may be the same, Alternatively, they may be different. Moreover, the N atom in Formula (2) and the _{O atom in R 3 and R 4} are not directly bonded, Y is a number of 0 or more and 2 or less, and Z is a number of 1 or more and 2 or less.

For example, in the above formula (2), when R ₃ is an oxyalkylene group represented by -AO- and Y is 1 to 2, the O atom in the shortest oxyalkylene group is adjacent to _{(R 3} ) _Y It is bonded to the H atom. In addition, when R ₃ is a methylene group, (R ₃ ) _Y is represented by -(CH ₂ ) _Y -, and when Y is 1 to 2, it is bonded to an adjacent H element and a methyl group (-CH ₃ ), or, Ethyl group (-CH ₂ -CH ₃ ) is formed. Moreover, when R ₄ is an oxyalkylene group represented by -AO-, the O atom in the shortest oxyalkylene group is bonded to the H atom adjacent to _{(R 4} ) _Z.

In the formula (2), when Y is 0, the amine-based dispersant becomes a secondary amine having _{-R 2} , one hydrogen group, and -(R ₄ ) _{z H.} For example, when Y is 0 and Z is 2, the amine-based dispersant is an alkyl group having 8 to 16 carbon atoms, an alkenyl group, or an alkynyl group, one hydrogen group, and -(R ₄ ) ₂ H , A dioxyethylene group or a dioxypropylene group, and the H element bonded to each other to obtain a secondary amine composed of _{-(AO) 2 H.}

In addition, in the above formula (2), when Y is 1, the amine-based dispersant becomes a tertiary amine having _{-R 2} , -R ₃ H and -(R ₄ ) _{z H.} And, when Y is 2, the amine-based dispersant is -R ₂ and -(R ₃ ) ₂ H phosphorus, a dioxyethylene group, a dioxypropylene group, or any of an ethylene group and an H element are- (AO) ₂ H, or -C ₂ H _5, and, - (R ₄₎ is a tertiary amine having a H _z.

The amine-based dispersant represented by the above formula (2) can be used by selecting, for example, a commercially available product that satisfies the above characteristics. Further, the amine-based dispersant may be prepared so as to satisfy the above characteristics by using a conventionally known production method.

The blending ratio of the amino acid-based dispersant and the amine-based dispersant contained in the conductive paste (amino acid-based dispersant/amine-based dispersant) is a mass ratio in the range of 1/4 or more and 1/2 or less. In particular, when the blending ratio of the amino acid-based dispersant and the amine-based dispersant is 1/4 or more and 2/5 or less, the viscosity stability of the conductive paste is very high.

When the lower limit of the blending ratio of the amino acid-based dispersant and the amine-based dispersant is 1/4 or more, the effect of improving the viscosity of the conductive paste over time is further improved, and the dispersibility of the conductive powder is improved, and a high drying film is obtained. It can have surface smoothness and high dry film density. In addition, when the upper limit of the blending ratio of the amino acid-based dispersant and the amine-based dispersant is 1/2 or less, the amine-based dispersant is relatively large, so that the change in the viscosity of the conductive paste over time can be greatly reduced.

The total content of the amino acid dispersant represented by the formula (1) and the amine dispersant represented by the formula (2) is 0.7% by mass or more and 1.2% by mass or less with respect to the entire conductive paste. When the total content of the amino acid-based dispersant and the amine-based dispersant is within the above range, the dispersibility of the conductive paste is improved, a dry film having a high dry film density and excellent surface smoothness can be obtained, and the dispersant remains. It is possible to suppress a sheet attack caused by the problem and a defect in peeling of the green sheet.

When the lower limit of the total content of the amino acid-based dispersant and the amine-based dispersant is 0.7% by mass or more, in a conductive paste containing the amino acid-based dispersant and the amine-based dispersant at the above-described mixing ratio, the dispersibility is further improved. It is possible to have a high dry film smoothness and dry film density, and to further reduce a change in the viscosity of the conductive paste over time. In addition, when the upper limit of the total content of the amino acid-based dispersant and the amine-based dispersant is 1.2% by mass or less, the residual amount of the dispersant on the surface of the dried film is further reduced, and adhesion between the surface of the dried film and the surface of the green sheet during lamination and compression. It is inhibited from causing peeling by inhibiting.

Further, the conductive paste may contain dispersants other than the above-described amino acid-based dispersant and amine-based dispersant within a range that does not impair the effects of the present invention. Dispersants other than the above may contain, for example, acid-based dispersants containing higher fatty acids, polymeric surfactants, etc., cationic dispersants other than acidic dispersants, nonionic dispersants, amphoteric surfactants and polymeric dispersants, etc. . In addition, these dispersants may be used alone or in combination of two or more.

(Conductive paste)

The conductive paste of this embodiment can be produced by preparing each of the above components, and stirring and kneading them with a mixer. At that time, if a dispersant is applied to the surface of the conductive powder in advance, the conductive powder does not aggregate and dissolves sufficiently, and the dispersant spreads widely on the surface, so that a uniform conductive paste can be easily obtained. In addition, a binder resin is dissolved in an organic solvent for a vehicle to prepare an organic vehicle, and a conductive powder, ceramic powder, an organic vehicle and a dispersant are added to the organic solvent for a paste, followed by stirring and kneading with a mixer to prepare a conductive paste. You may make it.

Moreover, it is preferable to use the same organic solvent for a paste as the organic solvent for a vehicle among the organic solvents, in order to improve the compatibility of the organic vehicle, for adjusting the viscosity of the conductive paste. The content of the organic solvent for a vehicle is, for example, 5 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the conductive powder. In addition, the content of the organic solvent for a vehicle is preferably 10% by mass or more and 40% by mass or less with respect to the total amount of the conductive paste.

When the viscosity of the conductive paste after 24 hours of production of the conductive paste is taken as a reference (0%), the viscosity after standing for 28 days from the reference date is preferably within ±10%. In addition, the viscosity of the conductive paste can be determined by, for example, the method described in Examples (a method of measuring under conditions of ^{10 rpm (shearing speed = 4 sec -1) using a Brookfield type B viscometer).} Can be measured.

Moreover, the surface smoothness of the dried film formed by printing a conductive paste can be evaluated by surface roughness. In addition, the surface roughness of the conductive paste is measured, for example, by the method described in Examples (a method of measuring the arithmetic mean height Sa based on the standard of ISO 25178 using VK-X120 manufactured by Keyence Corporation). can do. When the surface smoothness of the dried film is evaluated by the arithmetic average height Sa, the value is preferably 0.17 µm or less.

The conductive paste can be suitably used for electronic components such as multilayer ceramic capacitors. The multilayer ceramic capacitor has a dielectric layer formed using a 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 green sheet and the ceramic powder contained in the conductive paste are powders having the same composition. In the multilayer ceramic capacitor manufactured using the conductive paste of the present embodiment, even when the thickness of the green sheet is 3 μm or less, sheet attack and defects in peeling of the green sheet are suppressed.

[Electronic parts]

Hereinafter, embodiments such as the electronic component of the present invention will be described with reference to the drawings. In the drawings, it may be appropriately represented schematically or may be represented by changing the scale. Moreover, the position, direction, etc. of a member are demonstrated with reference to the XYZ rectangular coordinate system shown in FIG. 1A etc. as appropriate. 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-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 an external electrode 20 in which dielectric layers 12 and internal electrode layers 11 are alternately stacked.

Hereinafter, a method of manufacturing a multilayer ceramic capacitor using the conductive paste will be described. First, a conductive paste is printed on a green sheet and dried to form a dried film. A ceramic laminate 10 in which the internal electrode layers 11 and the dielectric layers 12 are alternately laminated by laminating and pressing a plurality of green sheets having the dried film on the upper surface to obtain a laminate, and then firing the laminate to integrate it. ) Is produced. After that, the multilayer ceramic capacitor 1 is manufactured by forming a pair of external electrodes 20 at both ends of the ceramic multilayer body 10. Hereinafter, it demonstrates in more detail.

First, a green sheet, which is an unfired ceramic sheet using a dielectric material, is prepared. As this 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 raw material powder of a predetermined ceramic such as barium titanate, etc. It applies to a support film in a sheet form, and what is dried and the thing which removed a solvent, etc. are mentioned. In addition, the thickness of the green sheet is not particularly limited, but from the viewpoint of a request for miniaturization of the multilayer ceramic capacitor, it is preferably 0.05 µm or more and 3 µm or less.

Subsequently, on one side of this green sheet, a plurality of sheets of the above-described conductive paste is printed (coated) and dried by a known method such as a screen printing method, and a dried film is formed. In addition, the thickness of the conductive paste after printing is preferably set such that the thickness of the dried film after drying becomes 1 µm or less from the viewpoint of a request for thinning of the internal electrode layer 11.

Next, the green sheet is peeled from the support film, and the green sheet and the dried film formed on one side thereof are laminated so that they are alternately disposed, and then a laminate is obtained by heating and pressing treatment. Moreover, it is good also as a structure in which the protective green sheet which is not coated with a conductive paste is additionally arrange|positioned on both surfaces of a laminated body.

Next, after cutting the laminate into 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 the ceramic laminate 10. In addition, it is preferable to set the atmosphere in the binder removal process to atmosphere or an N _{2 gas atmosphere.} The temperature at the time of performing the binder removal treatment is, for example, 200°C or more and 400°C or less. Moreover, it is preferable to make the holding time of the said temperature at the time of carrying out a binder removal process into 0.5 hour or more and 24 hours or less. In addition, firing is performed in a reducing atmosphere in order to suppress oxidation of the metal used for the internal electrode layer, and the temperature at the time of firing the laminate is, for example, 1000°C or more and 1350°C or less, and firing The holding time of the temperature when performing is, for example, 0.5 hours or more and 8 hours or less.

By firing the green chip, the organic binder in the green sheet is completely removed, the ceramic raw material powder is fired, and the ceramic dielectric layer 12 is formed. In addition, while the organic vehicle in the dried film is removed, nickel powder or nickel-based alloy powder is sintered, melted, or integrated to form the internal electrode layer 11, thereby forming a plurality of dielectric layers 12 and internal electrode layers 11. A multilayer ceramic sintered body stacked in turns is formed. Further, from the viewpoint of introducing oxygen into the interior of the dielectric layer to increase reliability and suppressing reoxidation of the internal electrodes, an annealing treatment may be performed on the fired multilayer ceramic fired body.

And by forming a pair of external electrodes 20 with respect to the produced multilayer ceramic fired body, the multilayer ceramic capacitor 1 is manufactured. 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 the material of the external electrode 20, for example, copper, nickel, or an alloy thereof can be preferably used. In addition, the electronic component is not limited to the multilayer ceramic capacitor, and may be an electronic component other than the multilayer ceramic capacitor.

Example

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

[Materials used]

(Conductive powder)

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

(Ceramic powder)

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

(Binder resin)

As the binder resin, ethyl cellulose resin and polyvinyl butyral resin (PVB resin) were used. In addition, the binder resin prepared as a vehicle dissolved in terpineol was used.

(Dispersant)

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

(2) As an amine-based dispersant, in the general formula (2), R ₂ = C ₁₂ H ₂₅ , R ₃ = C ₂ H ₄ O, R ₄ = C ₂ H ₄ O, Y = 1, Z = 1 The indicated dispersant was used.

(Organic solvent)

As the organic solvent, terpineol was used.

[Example 1]

Ni powder 46% by mass, ceramic powder 11.5% by mass, 3.2% by mass of the binder resin in the vehicle (consisting of ethylcellulose resin and polyvinyl butyral resin) in total, 0.2% by mass of amino acid-based dispersant, 0.6% by mass of amine-based dispersant %, and terpineol (organic solvent) as the balance as a whole were blended so as to be 100% by mass, and these materials were mixed to prepare a conductive paste. The viscosity stability, dispersibility (dry film density, surface roughness of the dry film), and adhesion of the produced conductive paste were evaluated by the following methods. Table 1 shows the evaluation results.

[Assessment Methods]

(Viscosity stability: Viscosity change amount of conductive paste)

After 24 hours of preparation of the conductive paste was taken as the reference time point, the viscosity of each sample after the reference time point and left to stand for 7 days, 14 days, and 28 days from the reference time point at room temperature (25° C.) was determined as follows It was measured as. And, when the viscosity of the (reference point) after 24 hours of production is taken as the reference (0%), the amount of change in the viscosity of the sample after each stationary is expressed as a percentage (%) ([(Viscosity after setting-24 hours for production) Viscosity after passage)/Viscosity after 24 hours of production] × 100) was calculated, and it was set as the amount of change in viscosity. The viscosity of the conductive paste was measured under conditions of 10 rpm (shear speed = 4 sec ^{-1) using a Brookfield B-type viscometer.} Further, the smaller the amount of change in the viscosity of the conductive paste is, the more preferable. The case where the amount of change in the viscosity of the conductive paste after standing for 28 days was 10% or less was referred to as "A", and the case exceeded 10% was referred to as "B", and the viscosity stability of the conductive paste was evaluated.

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

<Surface roughness>

On a heat-resistant tempered glass of 2.54 cm (1 inch) in width and height, the prepared conductive paste was screen-printed and dried at 120° C. in air for 1 hour to prepare a dried film having a width of 20 mm and a film thickness of 1 to 3 μm. . When the dispersibility of the conductive paste is good, the surface of the dried film becomes a smooth film. When the dispersibility is inferior, aggregation occurs in the conductive paste, the surface of the dried film becomes rough, and the smoothness of the surface decreases. So, using a laser microscope (VK-X120 manufactured by Keyence Corporation), the surface roughness Sa (arithmetic mean height) and Sz (maximum height) of the produced dried film were measured based on the standard of ISO 25178. The smaller the values of the surface roughness Sa (arithmetic mean height) and Sz (maximum height), the smoother the surface of the dried film is.

＜Dry Film Density (DFD)＞

The prepared conductive paste was placed on a PET film, and spread with an applicator having a width of 50 mm and a gap of 125 µm to a length of about 100 mm. After drying the obtained PET film at 120° C. for 40 minutes to form a dried body, the dried body was cut into 4 sheets of 2.54 cm (1 inch) horizontally and vertically, and after peeling the PET film, the thickness and mass of each of the 4 dried films were determined. It measured and calculated the dry film density (average value). The dispersibility of the conductive paste is low, and when the conductive powder causes agglomeration, the density of the dried film decreases, and the electrical properties may be inferior. The higher the dry film density, the better the dispersibility.

<Evaluation of dispersibility>

When the surface roughness Sa (arithmetic mean height) of the dry film described above is 0.17 µm or less, and the dry film density DFD is 5.50 g/cm 3 or more, it is referred to as "A", and the surface roughness Sa (arithmetic mean height) of the dried film is 0.17 Dispersibility was evaluated as "B" in the case where it is larger than µm and the case where the dry film density DFD is less than 5.50 g/cm 3, or both are satisfied.

(Adhesion)

The produced conductive paste was printed (applied) on a green sheet by a screen printing method, dried, and a plurality of products having a dry film formed on the green sheet were produced. Five of these sheets were laminated, followed by thermocompression treatment at 80°C and a pressure of 100 kg/cm 2 for 3 minutes to form a laminate. In the obtained laminate, when the adhesion between the dry film surface (electrode layer surface) and the bottom surface of the green sheet laminated thereon is weak, and peeling occurs at even one point, ``x'', otherwise, if peeling has not occurred. Was taken as "○", and adhesiveness was evaluated.

[Examples 2 and 3, Comparative Examples 1 and 2]

A conductive paste was prepared under the same conditions as in Example 1, except that the contents of the amino acid-based dispersant and the amine-based dispersant were set as the amounts shown in Table 1, and the mixing ratio of the dispersant was changed. The amount of change in the viscosity of the produced conductive paste, the density of the dried film, the surface roughness of the dried film, and the adhesion were evaluated by the above method. Table 1 shows the evaluation results.

[Examples 4 to 6, Comparative Examples 3 and 4]

A conductive paste was prepared under the same conditions as in Example 1, except that the content of the amino acid-based dispersant and the amine-based dispersant was set as the amount shown in Table 2 with a constant mixing ratio of the dispersant, and the total content of the dispersant in the conductive paste was changed. . The amount of change in the viscosity of the produced conductive paste, the density of the dried film, the surface roughness of the dried film, and the adhesion were evaluated by the above method. Table 2 shows the evaluation results.

[Evaluation results]

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

On the other hand, the conductive paste of Comparative Example 1, which has a low blending ratio of an amino acid-based dispersant and an amine-based dispersant, and contains a large amount of an amine-based dispersant, has good viscosity stability, but has a dry film density of 5.5 g/cm 3 or less, and the surface roughness Sa Was more than 0.17 µm, and the dispersibility was low as compared with the conductive paste of Example. Moreover, the surface roughness Sz (maximum height) also showed a slightly larger value compared with the Example. In addition, in the conductive paste of Comparative Example 2, which had a high blending ratio of the amino acid-based dispersant and the amine-based dispersant, and contained a large amount of the amino acid-based dispersant, the amount of change in the viscosity of the conductive paste after 28 days was 16.7%, which was changed by 10% or more.

In addition, the conductive paste of Comparative Example 3 in which the total content of the amino acid-based dispersant and the amine-based dispersant was less than 0.7% by mass had low dispersibility and low viscosity stability as compared with the conductive paste of Examples. In addition, the conductive paste of Comparative Example 4 in which the total content of the amino acid-based dispersant and the amine-based dispersant exceeds 1.2% by mass may cause peeling in the laminate produced using this, compared with the conductive paste of the example. , The adhesion was deteriorated.

In addition, the technical scope of the present invention is not limited to the aspects described in the above-described embodiments and the like. One or more of the requirements described in the above-described embodiments and the like may be omitted in some cases. In addition, the requirements described in the above-described embodiment and the like can be appropriately combined. In addition, to the extent permitted by laws and regulations, the contents of the Japanese patent application 2018-139501, which is a Japanese patent application, and all documents cited in this specification, are used as part of the description of the text.

Industrial applicability

The conductive paste according to the present embodiment is excellent in dispersibility, so that the smoothness of the dried film after application and the density of the dried film are excellent, and the viscosity stability over time is very good. It can be preferably used as a raw material for internal electrodes of multilayer ceramic capacitors that are chip parts (electronic parts) of electronic devices.

1: Multilayer ceramic capacitor
10: ceramic laminate
11: internal electrode layer
12: dielectric layer
20: external electrode
21: external electrode layer
22: plating layer

Claims (11)

As a conductive paste containing conductive powder, ceramic powder, dispersant, binder resin, and organic solvent,
The dispersant contains an amino acid-based dispersant represented by the following general formula (1) and an amine-based dispersant represented by the following general formula (2),
The blending ratio of the amino acid-based dispersant and the amine-based dispersant (amino acid-based dispersant/amine-based dispersant) is in the range of 1/4 or more and 1/2 or less by mass,
The conductive paste, wherein the total content of the amino acid-based dispersant and the amine-based dispersant is 0.7% by mass or more and 1.2% by mass or less with respect to the entire conductive paste.

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

(However, in formula (2), R ₂ represents an alkyl group having 8 to 16 carbon atoms, an alkenyl group, or an alkynyl group, R ₃ represents an oxyethylene group, an oxypropylene group, or a methylene group, and R ₄ represents an oxy An ethylene group or an oxypropylene group is represented, and R ₃ and R ₄ may be the same or different, and the N atom in formula (2) and the _{O atom in R 3 and R 4} are not directly bonded. In addition, Y is a number of 0-2, and Z is a number of 1-2.) The method of claim 1,
In the general formula (1), R ₁ represents a linear hydrocarbon group having 10 to 20 carbon atoms. The method according to claim 1 or 2,
The conductive paste, wherein the conductive powder contains at least one metal powder selected from Ni, Pd, Pt, Au, Ag, Cu, and alloys thereof. The method according to any one of claims 1 to 3,
A conductive paste containing 40% by mass or more and 60% by mass or less with respect to the entire conductive paste. The method according to any one of claims 1 to 4,
The conductive paste, wherein the conductive powder has an average particle diameter of 0.05 µm or more and 1.0 µm or less. The method according to any one of claims 1 to 5,
The ceramic powder is a conductive paste containing a perovskite type oxide. The method according to any one of claims 1 to 6,
The conductive paste, wherein the ceramic powder has an average particle diameter of 0.01 µm or more and 0.5 µm or less. The method according to any one of claims 1 to 7,
The conductive paste containing at least one of a cellulose resin, an acrylic resin, and a butyral resin. The method according to any one of claims 1 to 8,
Conductive paste for internal electrodes of multilayer ceramic capacitors. An electronic component formed using the conductive paste according to any one of claims 1 to 8. A multilayer ceramic capacitor comprising a laminate in which an internal electrode layer formed using the conductive paste according to claim 9 and a dielectric layer are laminated.

Images