TW201431982A - Conductive paste composition - Google Patents

Abstract

The invention set forth herein provides a conductive paste composition that suppresses chemical attack, even in extremely thin ceramic green sheets, and enables high printing precision to be achieved. The conductive paste composition includes a conductive powder, a binder, and an organic solvent. The organic solvent contains isobornyl acetate as a primary solvent, and a solvent having a Hansen solubility parameter lower than that of isobornyl acetate as a secondary solvent.

Description

Conductive paste composition Technical field

The present invention relates to a conductive paste composition. More specifically, it relates to a conductive paste composition suitable for use in forming an internal electrode of a laminated ceramic electronic component.

In addition, the present application claims the priority of Japanese Patent Application No. 2012-244846, filed on Nov. 6, 2012, the entire content of which is hereby incorporated by reference.

Background technique

With the recent miniaturization and high integration of electronic devices, the structure has been miniaturized in electronic components mounted on electronic devices. For example, in an electronic component such as a multilayer capacitor or a laminated ceramic wiring substrate, further miniaturization and thinning are required.

Fig. 1 is a structural view showing a multilayer ceramic capacitor (hereinafter sometimes referred to simply as "MLCC"). MLCC 10 is a chip-type ceramic capacitor in which a plurality of dielectric layers 20 made of a ceramic such as titanium oxide or barium titanate and an internal electrode layer 30 made of a conductive film such as nickel are stacked, and is excellent in utilizing ceramic materials. The advantages of high-frequency characteristics and the like can be reduced in size and capacitance, and therefore, they are used in a wide range of electronic circuits.

Typically, the aforementioned MLCC 10 is manufactured by the following steps. In other words, a ceramic slurry is formed by adding a binder, an organic solvent, or the like to a ceramic powder, and applying the slurry to a substrate by a doctor blade method or the like to form a ceramic green sheet for forming the dielectric layer 20. Sometimes it is just called "embryo".). Further, on the green sheet, a conductive paste composition containing a conductive powder, a binder, and an organic solvent is applied in a predetermined pattern by a printing method such as a screen printing method, and is formed to constitute the internal electrode layer 30. Conductive coating film. Next, the predetermined number of sheets of the green sheet having the conductive coating film prepared in accordance with the above (for example, tens to hundreds of sheets) is baked, and then baked, and then the external electrode 40 is formed. The MLCC 10 in which the internal electrode layer 30 and the dielectric layer 20 are laminated is obtained.

In the manufacturing process of the above MLCC 10, the binder which is blended into the slurry for the green sheet is a butyraldehyde-based resin or an acrylic resin which is excellent in adhesion to ceramic particles. On the other hand, the organic solvent to be blended in the conductive paste composition preferably has an affinity for the green sheet, but suppresses dissolution of the binder such as butyral resin or acrylic resin in the green sheet to etch the embryo. The eclipse of the film (hereinafter also referred to as "slice etch").

Here, an organic solvent such as terpineol has been widely used in the conductive paste composition of electronic parts. However, since the terpineol has a high solubility in a butyral resin or an acrylic resin, it is difficult to be referred to as a conductive paste composition suitable for use in forming the internal electrode layer 30 of the MLCC 10. Therefore, it is disclosed that the conductive paste composition for forming the internal electrode layer 30 of the MLCC 10 is an organic solvent which is used in place of the terpineol and which has an effect of suppressing the affinity and the chipping of the green sheet (for example, Li literature 1~5, etc.).

Advanced technical literature Patent literature

[Patent Document 1] Japanese Patent Application Publication No. 2006-203185

[Patent Document 2] Japanese Patent Application Publication No. 2007-084690

[Patent Document 3] Japanese Patent Application Publication No. 2007-149994

[Patent Document 4] Japanese Patent Application Publication No. 2006-134726

[Patent Document 5] Japanese Patent Application Publication No. 2006-202502

Summary of invention

However, the above-mentioned chipping phenomenon can be tolerated when the ceramic green sheet is thick, but as the ceramic green sheet is thinned, the influence thereof will be invented, and therefore, it is required to be evaluated on a more stringent basis.

For example, the size of the MLCC 1005 (outer size: 1.0mm × 0.5mm × 0.5mm) is gradually miniaturized to 0603 size (outer size: 0.6mm × 0.3mm × 0.3mm) or 0402 size (outer size: 0.4 The thickness of one layer of the dielectric layer in the ultra-small MLCC is thinned to a level of, for example, less than 3 μm or even 1 μm or less from the conventional level of 3 μm to 5 μm. Further, even in the case of the conventional MLCC having a large outer shape, the number of layers in the internal layer is increased while the size thereof is maintained, so that the thickness of one layer of the dielectric layer is continuously thinned to a level of less than 1 μm.

Therefore, in the manufacture of MLCC, it is hoped that the realization will achieve higher printing precision. A conductive paste composition which does not cause a problem of chipping on the thin ceramic green sheets at the same time.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a conductive paste composition which can attain high printing precision and can suppress chipping for an extremely thin ceramic green sheet.

In order to achieve the above object, according to the present invention, a conductive paste composition containing a conductive powder, a binder, and an organic solvent can be provided. The conductive paste composition is characterized in that the aforementioned organic solvent contains: acetic acid Ester as the main solvent; and Hansen solubility parameter is lower than the aforementioned acetic acid The solvent of the ester serves as a secondary solvent.

Acetic acid used as a main solvent in the conductive paste composition of the present invention The ester showed good solubility to the binder component of the conductive paste composition, but showed solubility in the butyral resin used in the ceramic green sheet. Therefore, for example, it is pointed out in paragraph 0018 of Patent Document 5 that if the solvent component is acetic acid Ester, it is difficult to completely avoid the phenomenon of chipping. Therefore, acetic acid The ester is difficult to say as a material suitable for use as a main solvent for producing a conductive paste composition such as MLCC.

In this regard, in the present invention, the organic solvent of the conductive paste composition is the acetic acid different Ester as the main solvent, and the Hansen solubility parameter is lower than the acetic acid The solvent of the ester acts as a secondary solvent, and the acetic acid is inhibited by using both The ester is etched on the ceramic green sheet.

In addition, the "butyraldehyde-based resin" is used as a binder for forming a ceramic green sheet in such a field, and includes a so-called butyraldehyde-based resin. The term "all ethylene vinylene resin". The polyvinyl butyral resin is a resin composition containing polyvinyl butyral in a proportion of 50% by mass or more (for example, 70% by mass or more).

Further, in terms of printing accuracy in printing a conductive paste composition, for example, the paste film printed on the surface of the ceramic green sheet may spread or bleed and spread on the contact surface with the ceramic green sheet, and therefore the printing accuracy is generally considered. Will decrease. In the conductive paste composition of the present invention, even if the size of the printed pattern is fine (especially, the thickness is thinned), the shape of the paste film may be suppressed from being dripped or bleed with respect to the size of the printed pattern. Small, therefore, the printing accuracy can be highly maintained.

In addition, the Hansen Solubility Parameter (HSP) is an indicator of the solubility of a substance dissolved in other substances. The HSP is different in its idea of the SP value of Hildebrand used in the Solvent Handbook (issued by the Society) and represents the solubility by a multidimensional (typically three-dimensional) vector. Representatively, the vector can be represented by a scatter term, a polar term, and a hydrogen bond term. The dispersion term reflects the effect of the Van der Waals force, the polarity term reflects the dipole moment, and the hydrogen bond term reflects the effect of water, alcohol, and the like. Further, vector similarities due to HSP can be judged to be highly soluble. Further, depending on the HSP, it is also possible to determine whether a certain substance is likely to exist in another substance, that is, how good the dispersibility is.

Acetic acid The HSP of the ester is 19.0 (J/cm ³ ) ^1/2 , and in the present invention, a solvent having an HSP of less than 19.0 (J/cm ³ ) ^1/2 can be used as a sub-solvent. Such HSP can be referred to, for example, the values disclosed in Wesley L. Archer, Industrial Solvents Handbook, and the like.

In an ideal aspect of the conductive paste composition disclosed herein, the aforementioned organic solvent contains the aforementioned acetic acid in proportion. The ester is 60% by mass to 90% by mass, and the aforementioned sub-solvent is 40% by mass to 10% by mass.

If the above configuration is used, In the conductive paste composition in which the ester is used as the main solvent, the affinity for the ceramic green sheet and the effect of suppressing the chipping can be balanced.

In one aspect of the conductive paste composition disclosed herein, the Hansen solubility parameter of the above-mentioned sub-solvent is less than 19, and contains any one or two or more of the following, namely: (A) An alcohol derivative; (B) a compound represented by the following formula (1), R ¹ (OR ² ) _n OR ³ (1)

(In the formula, R ¹ represents a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms, R ² represents a linear or branched alkyl group having 2 to 4 carbon atoms, and R ³ represents hydrogen. An atom, an ethylidene group or a linear or branched alkyl group, and n is 1 or 2); and (C) a hydrocarbon.

In the solvents of the above (A) to (C), from the correlation of the vector of HSP, HSP of less than 19.0 (J/cm ³ ) ^1/2 can effectively suppress the difference in acetic acid as a main solvent. A solvent for the etch resistance of esters to ceramic green sheets. Therefore, by using the solvent as a sub-solvent, it is possible to provide a conductive paste composition which has affinity with a ceramic green sheet and can suppress sheet corrosion more effectively.

In a preferred aspect of the conductive paste composition disclosed herein, the metal species constituting the conductive powder is selected from any one or two of the group consisting of nickel, platinum, palladium, silver, and copper. More than one species.

These nickel, platinum, palladium, silver, and copper are all metal materials having excellent electrical conductivity and heat resistance at the firing temperature of, for example, ceramic green sheets, and are suitable as conductive powders. Further, the alloy containing the metal species and various conductive metal compounds may have characteristics suitable as the conductive powder. According to the foregoing configuration, for example, a conductive paste composition suitable for forming an internal electrode of a laminated ceramic capacitor can be provided.

In one of the desirable aspects of the conductive paste composition disclosed herein, it is prepared to be used in a group consisting of spray coating, roller coating, screen printing, gravure printing, lithography, and inkjet printing. Any of the printing methods.

In the printing of the ceramic green sheet as the object to be printed, the conductive paste composition of the present invention has an appropriate degree of fusion to the sheet, but can suppress the chipping property. Therefore, it can be applied to various printing methods. For example, it is suitable for a gravure printing method which is difficult to apply to a screen printing method and which can print a thinner conductive coating film with higher precision and good productivity.

In the conductive paste composition of the present invention as described above, in the printing of the ceramic green sheet as the object to be printed, it is possible to print a thinner conductive layer with high precision and good productivity by, for example, a gravure printing method. Sex film. Therefore, it is preferable to use the internal electrode for forming a multilayer ceramic capacitor to more clearly exhibit its advantages.

10‧‧‧Multilayer Ceramic Capacitors (MLCC)

20‧‧‧Dielectric layer (ceramic slab)

30‧‧‧Internal electrode layer

40‧‧‧External electrode

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a partially cutaway perspective sectional view showing the structure of a multilayer ceramic capacitor.

2(a) and (b) are conductive paste compositions 1 produced in the printing examples, respectively. And an example of a cross-sectional shape diagram of the electrode pattern obtained by 2.

Form for implementing the invention

Hereinafter, preferred embodiments of the present invention will be described. In addition, matters other than those specifically mentioned in the present specification and which are necessary for the implementation of the present invention (for example, a method of preparing a conductive paste composition, a method of imparting a substrate, a baking method, etc.) can be made according to the field. The prior art of the prior art is subject to the design of a person of ordinary skill in the art. The present invention can be implemented in accordance with the teachings of the present disclosure and the technical common knowledge in the field.

The conductive paste composition disclosed herein essentially contains a conductive powder, a binder, and an organic solvent. Here, the conductive powder is uniformly dispersed in a carrier (organic medium) typically composed of a binder and an organic solvent.

[conductive powder]

The conductive powder is a material which is electrically conductive to a calcined body (typically, a conductive film) obtained by firing a conductive paste composition. The type and the like of the conductive powder are not particularly limited, and various conductive powders conventionally used in the intended conductive paste composition can be used without particular limitation.

The conductive paste composition may be used for various forms such as an electrode layer, a printed circuit, a bonding, a resistor, or an anisotropic conductive ink, and an example of a material constituting the conductive powder may be exemplified by gold ( Au), silver (Ag), copper (Cu), platinum (Pt), palladium (Pd), ruthenium (Ru), rhodium (Rh), iridium (Ir), osmium (Os), nickel (Ni), and aluminum ( Metals such as Al) and alloys thereof; carbonaceous materials such as carbon black; LaSrCoFeO ₃ -based oxides (for example, LaSrCoFeO ₃ ), LaMnO ₃ -based oxides (for example, LaSrGaMgO ₃ ), and LaFeO ₃ -based oxides (for example, LaSrFeO) ₃ ) A conductive ceramic represented by a transition metal perovskite oxide represented by a LaCoO ₃ -based oxide (for example, LaSrCoO ₃ ) or the like. Although it is not particularly limited, when the conductive paste composition is used for the purpose of forming an internal electrode layer of MCLL, for example, it is preferable that nickel (Ni) or platinum (Pt) is not melted even at the calcination temperature. Any one or two or more kinds of metal species of palladium (Pd), silver (Ag), and copper (Cu). Further, the conductive powders may of course contain impurities in a range which does not impair the characteristics of the conductive paste composition of the present invention.

The shape or particle diameter of the particles is not strictly limited. For example, it is possible to use an average particle diameter selected from those having a mean particle diameter of several nm to several μm, for example, 10 nm to 10 μm, depending on the use or the like. particle. In addition, the "average particle diameter" in the present specification is substantially in the range of 0.5 μm or more in the average particle diameter, and can be obtained by laser scattering. The particle size distribution measured by the particle size distribution measuring apparatus of the diffraction method is 50% of the cumulative value (50% by volume average particle diameter; hereinafter, also abbreviated as D50), and the average particle diameter is approximately 0.5 μm or less. In the range, the particle diameter of the particle size distribution of 50% of the particle size distribution of the plurality of particles in the observation image observed by the observation means such as an electron microscope can be obtained. Further, the particle size range in which the calculation method of the average particle diameter is applied is not critical, and the calculation method can be appropriately selected in accordance with the accuracy of the apparatus to be used and the like.

Further, when an electrode pattern as an internal electrode layer is printed on the surface of the ceramic green sheet constituting the MLCC, in order to realize a desired pattern size (pattern width, film thickness, and the like) and shape, coating of the conductive paste composition may be considered. the amount And coating form and the like. Here, the conductive powder suitable for forming the internal electrode layer of the MLCC is not particularly limited. However, it is preferable that the particles constituting the powder have an average particle diameter of 1 μm or less, and typically, 0.05 μm to 0.8 μm can be exemplified. It is preferable to form 0.05 μm to 0.4 μm.

The content of the conductive powder in the entire conductive paste composition disclosed herein is not particularly limited. However, when the total amount of the conductive paste composition is 100% by mass, it is preferably adjusted to conductive powder. It is 40% by mass or more and 95% by mass or less, and more preferably 40% by mass or more and 60% by mass or less. When the content of the conductive powder in the conductive paste composition produced is in the above range, a conductive film having high conductivity and further improving compactness can be formed.

[bonding agent]

The binder may be any one which can impart a good viscosity to the conductive paste composition and a coating film forming ability (adhesion to a substrate), and can be used without any particular limitation in the conventional conductive paste composition. For example, an acrylic resin, an epoxy resin, a phenol resin, an alkyd resin, a cellulose polymer, a polyvinyl alcohol, a rosin resin, or the like is used as a main component.

[Organic solvents]

The organic solvent belonging to the characteristic structure in the conductive paste composition disclosed herein contains acetic acid Ester as the main solvent, and contains Hansen solubility parameter (HSP) lower than acetic acid The solvent of the ester serves as a secondary solvent.

Acetic acid The ester is an oxygen-containing compound having a molecular formula of C ₁₂ H ₂₀ O ₂ , and an organic solvent which is a conductive paste composition has hitherto been used. However, it is known that the aforementioned acetic acid is different The solubility of the butyral resin in the ester alone is high, and it is difficult to completely suppress the chipping phenomenon of the ceramic green sheet or the like using the butyral resin. Therefore, in the present invention, the acetic acid is inhibited by using a suitable auxiliary solvent in combination. The eclipse of the ester.

The foregoing auxiliary solvent may be used in combination with HSP lower than acetic acid One or more of various solvents of the ester. Due to acetic acid The HSP of the ester is 19, and therefore, the sub-solvent can be exemplified by an HSP of less than 19, more preferably 15 to 18. More specifically, the sub-solvent is preferably any one or more of the following (A) to (C).

(A) Terpineol derivatives

The terpineol derivative in the present invention may be a structure in which at least one of hydrogen or a hydroxyl group at the terminal in the molecular structure of terpineol is substituted with an organic group, in addition to terpineol itself. It is known that terpineol has four isomers different from the position of a hydroxy double bond, α, β, γ, δ-terpineol, however, it can also be a terpineol of any of these. As a derivative of the main body. For example, a derivative of α-terpineol may, for example, be an α-terpineol derivative represented by the following formula (2).

Here, in the formula (2), R ²¹ , R ²² and R ²³ each independently represent a hydrogen atom or an organic group, and at least one of R ²¹ , R ²² and R ²³ is not a hydrogen atom.

R ²¹ and R ²² in the formula (2) are each independently an organic group, and are typically a hydrogen atom, an alkyl group or an alkoxy group.

The alkyl group is not particularly limited, however, it is preferably a linear or branched alkyl group having 1 to 14 carbon atoms, and more preferably a linear or branched alkyl group having 1 to 10 carbon atoms. Specifically, for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, an n-hexyl group and the like can be given.

The alkoxy group is not particularly limited, and examples thereof include a methoxy group, an ethoxy group, a propoxy group, a butoxy group and the like.

Among these, R ²¹ and R ^{22 are} preferably a hydrogen atom or an alkyl group, and more preferably a hydrogen atom or a methyl group.

R ²³ in the formula (2) is an organic group, and is typically a hydrogen atom, an alkyl group, an alkoxy group or a fluorenyl group. The alkyl group and the alkoxy group may be the same as described above. Typically, the fluorenyl group is formyl, methanoyl, acetyl, ethanoyl, propionyl, propanoyl, benzyl.醯基等.

Any of R ²¹ , R ²² and R ²³ must be an organic group.

The terpineol derivative is preferably an organic acid ester of terpineol, and specific examples thereof include, for example, dihydroterpineol acetate, dihydrofurfuryl propionate, and the like.

(B) alkylene glycol compound

The sub-solvent may, for example, be an alkylene glycol-based compound represented by the following general formula (1) in which HSP is less than 19.

R ¹ (OR ² ) _n OR ³ ...(1)

Here, in the formula, R ¹ represents a straight or branched alkyl group having 1 to 6 carbon atoms, R ² represents a linear or branched alkyl group having 2 to 4 carbon atoms, and R ³ represents a hydrogen atom or B. Amidino, and n is 1 or 2.

The alkylene glycol monoalkyl compound is not particularly limited, and, for example, ethylene glycol monoalkyl ethers, diethylene glycol monoalkyl ethers, propylene glycol monoalkyl ethers, and the like are exemplified. Propylene glycol monoalkyl ethers, tripropylene glycol monoalkyl ethers, ethylene glycol dialkyl ethers, diethylene glycol dialkyl ethers, propylene glycol dialkyl ethers, dipropylene glycol dialkyls Ethers, tri-propylene glycol dialkyl ethers, tri-propylene glycol trialkyl ethers, ethylene glycol monoalkyl ether acetates, diethylene glycol monoalkyl ether acetates, propylene glycol monoalkyl ethers Acetate, dipropylene glycol monoalkyl ether acetate, tripropylene glycol monoalkyl ether acetate, tripropylene glycol trialkyl ether acetate, ethylene glycol dialkyl ether acetate, two extension Ethylene glycol dialkyl ether acetates, propylene glycol dialkyl ether acetates, dipropylene glycol dialkyl ether acetates, and tripropylene glycol dialkyl ether acetates.

More specifically, it can be exemplified by ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, ethylene glycol dibutyl ether, and diethylene glycol alone. Ethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether acetate, and the like.

(C) hydrocarbon

The hydrocarbon may, for example, be various linear or branched hydrocarbons having an HSP of less than 19, and more desirably a linear saturated hydrocarbon. The hydrocarbon may be exemplified by a boiling point of 185 to 270 ° C at normal pressure, and more preferably a boiling point of 200 to 260 ° C under normal pressure. Although there is no particular limitation, the hydrocarbon having such a trait is generally included in more than 50% of the total carbon number of 20 or less, and typically the carbon number is 10 to 16. For example, C ₁₀ H ₂₂ , C ₁₁ H ₂₄ , C ₁₂ H ₂₆ , C ₁₃ H ₂₈ , C ₁₄ H ₃₀ , C ₁₅ H ₃₂ , C ₁₆ H _{34 can be cited} .

Among the above organic solvents, it is preferred that the acetic acid is different The proportion of the ester is 60% by mass to 90% by mass, and the proportion of the auxiliary solvent is 40% by mass to 10% by mass. More desirable is acetic acid The ester is 70% by mass to 90% by mass, and the remainder is a sub-solvent.

The proportion of the organic solvent in the entire conductive paste composition is preferably 5% by mass or more and 60% by mass or less, and is preferably 20% by mass or more and 60% by mass or less. In addition, the binder may be adjusted in accordance with the use of the conductive paste composition, etc., but the standard may be 1% by mass or more and 15% by mass or less of the total of the conductive paste composition, and preferably 1% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 7% by mass or less. By forming the above-described structure, it is preferable to easily form (coat and print) a coating film having a uniform thickness as a conductive film on a substrate to be printed, for example, and to facilitate handling.

Further, the conductive paste composition of the present invention is not limited to the other constituent components or the blending ratio (amount thereof) as long as the purpose thereof is achieved. For example, in addition to the conductive powder, it may be contained according to the use. Various constituent materials which exhibit desired characteristics, or additives which are generally used as a dispersing agent for such a conductive paste composition.

A typical component contained in addition to the conductive powder may, for example, be a ceramic powder or a glass powder. More specifically, it may be a fine powder or a glass powder of a ceramic raw material constituting the unfired ceramic green sheet of the object to be printed of the conductive paste composition. For example, such an additive may be added simultaneously when the conductive powder is mixed with a binder or an organic solvent or the like.

The above conductive paste composition disclosed herein and the conventional phase Also, typically, it can be easily prepared by mixing the aforementioned constituent materials. For example, a three-roll mill or other kneading machine can be used to mix the predetermined blend of conductive powder, binder and organic solvent. Stir. Further, when the conductive powder is mixed with another constituent material, the carrier may be prepared by mixing a binder and an organic solvent in advance, and a conductive powder or the like may be dispersed in the carrier to provide a slurry form (may be ink-like). ) the composition.

The conductive paste composition has, for example, affinity for the green sheet, but can suppress the chipping property, and can be printed on the green sheet by various printing methods by adjusting the viscosity to be suitable. For example, it can be suitably printed by a printing method such as spray coating, roll coating, screen printing, gravure printing, lithography, and inkjet printing. In particular, by printing by gravure printing, a high-quality printing pattern can be printed by high-speed printing, and can be suitably applied to, for example, an internal electrode in which a multilayer ceramic capacitor is formed.

The above-mentioned green sheet is not necessarily limited. For example, it is conceivable that the following green sheets are formed by combining a dielectric powder such as various ceramics with a binder composed of a butyral resin. Typically, the following may be applied to a dielectric powder in which a polyvinyl butyral resin and an organic solvent as a binder are mixed with a ceramic powder such as titanium oxide (TiO ₂ ) or barium titanate (BaTiO ₃ ). The body slurry is supplied to a predetermined position, and dried to remove the organic solvent, whereby the sheet is formed into a sheet (shell). The ceramic powder is not limited to the above examples, and dielectrics of various compositions are conceivable. Further, in addition to the above, the green sheet may contain various additives such as a dispersing agent and a plasticizer used in the formation of such a green sheet.

Hereinafter, embodiments related to the present invention will be described, however, it is not intended The drawings limit the invention to those shown in the following examples.

(Implementation 1) [Preparation of conductive paste composition]

A conductive paste composition (samples 1 to 8) was produced by the following procedure.

That is, first, mixing ethyl cellulose (EC) as a binder with acetic acid as a main solvent The ester (IBA) was stirred at 70 ° C for 24 hours, whereby the carrier was prepared. Next, a conductive powder, an additive, and a sub-solvent were placed in the carrier, and sufficiently kneaded by a three-roll mill to obtain a conductive paste composition (samples 1 to 8). Further, the sub-solvent is a solvent mixture of the combination shown in the following Table 1 according to the mass ratio: the sub-solvent is 70:30, and the viscosity of the conductive paste composition is 0.1 to 3 Pa. The range of s. In addition, Table 2 below shows the Hansen Solubility Parameter (HSP) of each of the sub-solvents.

Further, the additive is a powder of barium titanate (BaTiO ₃ ) which is used as a green sheet at the coating (printing) of the conductive paste composition. The conductive powder and the additive are blended in a ratio of 40 to 60% by mass of the conductive powder and 1 to 20 parts by mass of the additive to the entire paste composition.

Further, for the evaluation of the sheet-like property to be carried out later, the solvent of the main solvent and the sub-solvent was blended in a ratio of 70:30 (mass ratio) by the combination shown in Table 1.

[Preparation of ceramic embryos]

The object to be coated with the conductive paste composition is to prepare a ceramic green sheet. The ceramic green sheet is a blank for a dielectric layer of a imaginary MLCC, and a polyethylene butyral resin as a binder is mixed with a plasticizer and an organic solvent in a barium titanate (BaTiO ₃ ) as a dielectric powder. After the dielectric slurry of the powder is applied onto the support film, the dielectric slurry is dried and the organic solvent is removed to form a sheet.

[Evaluation of printability]

The conductive paste composition (samples 1 to 8) prepared as described above was applied onto the surface of the ceramic green sheet by a gravure printing method, and dried to form an electrode film (electrode pattern). . The cross-sectional shape characteristics (film thickness, surface roughness, and shape index) of the formed electrode pattern were measured by a laser displacement meter (manufactured by Keyence Co., Ltd.), and the printability was evaluated. The measurement contents and evaluation results are shown in Table 1 below.

Further, in Table 1, the film thickness is an average value of the thickness of the surface of the green sheet measured from an arbitrary measurement point of 9 or more electrode patterns to the surface of the electrode pattern, and the surface roughness is an arithmetic mean roughness Ra. Further, the shape index is a length of a portion (lower bottom) in which the electrode pattern is in contact with the green sheet in the cross section of the thin line portion of the electrode pattern (which may be a substantially square shape and a substantially trapezoidal cross-sectional shape), and The length of the upper portion of the electrode pattern is defined as the value of (b/a) when b is formed.

Further, Fig. 2 (a) and (b) show cross-sectional shape analysis images of the electrode patterns obtained from the conductive paste compositions of the samples 1 and 2, respectively.

[Evaluation of chip erosion]

When the conductive paste composition is printed on the ceramic green sheet, the organic solvent contained in the conductive paste composition dissolves the binder contained in the ceramic green sheet, and the electrode pattern may penetrate. To the ceramic green sheet, or dissolve the contact surface with the ceramic green sheet. Therefore, the solvent for evaluation of the chipping property prepared by the above is dropped on the ceramic green sheet, and the dryness is observed by visual observation. The lower portion of the drop was dried, whereby the chipping property was evaluated, and the results are shown together in Table 1. The evaluation result in Table 1 is that the surface of the ceramic green sheet is obviously dissolved and the sheet is broken, and "x" is formed. When the surface of the ceramic green sheet is dissolved, the sheet is not broken, and the sheet is not "△". When the surface of the ceramic green sheet is seen, the dissolver is made "○".

As shown in Table 1, the organic solvent uses only (d) acetic acid The electrode prepared by the conductive paste composition of the sample 1 of the ester was excellent in film thickness and surface roughness, but constituted a result of a slightly lower shape index. When the cross-sectional shape of the electrode pattern of FIG. 2(a) was observed, it was confirmed that the film thickness of both end portions of the electrode pattern was thin and the shape index was low. Further, in terms of the chipping property, although the sheet was not broken, it was found to be dissolved, and it was a problem in the thin film ceramic green sheet having a film thickness of about 1 μm or less. Therefore, the overall evaluation was "Δ".

In contrast, the main solvent of the organic solvent uses (d) acetic acid Ester, and the sub-solvent uses HSP lower than (d) acetic acid The conductive paste composition of Samples 2 to 4 of the ester solvent was good in film thickness, surface roughness, and shape index. For example, if the cross-sectional shape of the electrode pattern formed by the paste of the sample 2 is viewed in FIG. 2(b), the film thickness ratio of the film thickness of both ends of the electrode pattern (a) can be confirmed. Thick and high in shape index. From this, it was confirmed that the conductive paste compositions of Samples 2 to 4 were excellent in printability by gravure printing.

Further, in terms of the chipping property, although the conductive paste composition of the sample 4 was confirmed to have a few chipping properties, the conductive paste compositions of the samples 2 and 3 hardly saw the dissolution of the ceramic green sheets. Thus, the conductive paste composition of Samples 2 to 4 was evaluated as "○" in terms of printability and chipping property.

On the other hand, the main solvent of the organic solvent uses (d) acetic acid Ester, and the use of HSP in the secondary solvent is higher than (d) acetic acid In the conductive paste composition of the samples 5 to 8 of the solvent of the ester, although the film thickness and the shape index were good, the surface roughness was extremely rough, and it was confirmed that it was unsuitable for the pasteability of the printing property by gravure printing. Further, it was confirmed that the higher the HSP of the sub-solvent, the worse the chipping property. Therefore, in the conductive paste composition of the samples 5 to 8, the comprehensive evaluation of the printability and the chipping property was made "x".

(Implementation 2)

The main solvent and the sub-solvent of the organic solvent were changed to prepare a conductive paste composition (Sample 9). That is, as shown in Table 3 below, the main solvent uses (c) dihydrofurfuryl propionate instead of HSP to replace (d) acetic acid Ester, and the use of HSP in the secondary solvent is slightly greater than (d) acetic acid The (e) dihydroterpineol of the ester was prepared in the same manner as in the case of the first embodiment described above to prepare a conductive paste composition.

The conductive paste composition of the sample 9 and the conductive paste composition of the sample 2 produced by the first embodiment were applied and implemented by a gravure printing method. The surface of the same ceramic green sheet of the same pattern 1 was dried and thereby an electrode film (electrode pattern) was formed. In the gravure printing, the electrode pattern formed by using the plate making method different from that of the first embodiment was evaluated in the same manner as in the first embodiment, and the printability and the chipping property were evaluated. Compared with the plate making of the first embodiment, the plate making used in the second embodiment is a plate making process which can produce a film having a small film thickness and a high shape index. Table 3 below shows the evaluation results.

As shown in Table 3, the conductive paste composition of Sample 9 was excellent in printability. However, in terms of chipping property, although the sheet is not broken, it dissolves, and therefore, it poses a problem in a thin film ceramic sheet having a film thickness of about 1 μm or less. Conductive paste composition of sample 9 although the main solvent used HSP was less than (d) acetic acid The ester (c) dihydrofurfuryl propionate and the general-purpose (e) dihydroterpineol used as the auxiliary solvent have room for improvement in chipping property, and the overall evaluation is "△".

On the other hand, the conductive paste composition of the sample 2 showed good printability even in a finer print pattern, and the overall evaluation was "○".

(Implementation 3)

The ceramic green sheet is prepared from the same ceramic sheet and adhesive as the first embodiment, and the ceramic green sheet of the acrylic resin is used, and by gravure printing, The conductive paste composition of the sample 2 produced in the first embodiment was applied onto the surface of the green sheets and dried to form an electrode film (electrode pattern). In this gravure printing, a plate making different from the first and second embodiments is used. The electrode pattern thus formed was evaluated in the same manner as in the first embodiment, and the printability and the chipping property were evaluated. Table 4 below shows the evaluation results.

As shown in Table 4, the conductive paste composition of the sample 2 was excellent in both printability and chipping property, and was confirmed to be applied to various ceramic plates and ceramic green sheets of acrylic or butyral resin. In either case, they all have excellent quality.

Claims (6)

A conductive paste composition containing a conductive powder, a binder, and an organic solvent, and the organic solvent contains: acetic acid Ester as the main solvent; and Hansen solubility parameter is lower than the aforementioned acetic acid The solvent of the ester serves as a secondary solvent. The conductive paste composition of claim 1, wherein the aforementioned organic solvent contains the aforementioned acetic acid in proportion The ester is 60% by mass to 90% by mass, and the aforementioned sub-solvent is 40% by mass to 10% by mass. The conductive paste composition according to claim 1 or 2, wherein the second solvent has a Hansen solubility parameter of less than 19 and contains any one or more of the following: (A) a terpineol derivative; B) a compound represented by the following formula (1), R ¹ (OR ² ) _n OR ³ (1) (wherein, R ¹ represents a hydrogen atom or a straight or branched chain having 1 to 6 carbon atoms; Alkyl, R ² represents a straight or branched alkyl group having 2 to 4 carbon atoms, R ³ represents a hydrogen atom, an ethyl fluorenyl group or a linear or branched alkyl group, and n is 1 or 2); And (C) a hydrocarbon. The conductive paste composition according to any one of claims 1 to 3, wherein the metal species constituting the conductive powder is selected from any one or two of the group consisting of nickel, platinum, palladium, silver, and copper. More than one species. The conductive paste composition according to any one of claims 1 to 4, which is prepared to be used in a group consisting of spray coating, roller coating, screen printing, gravure printing, lithography, and inkjet printing. Any kind of printing method. The conductive paste composition according to any one of claims 1 to 5, which is prepared to be an internal electrode which can be used to form a laminated ceramic capacitor.