TWI754671B - conductive paste - Google Patents

Abstract

An object of the present invention is to provide a conductive paste that can form a conductive film having excellent adhesion to a substrate. According to the present invention, there is provided a conductive paste comprising a conductive powder, a resin binder, an organic additive and an organic solvent. The organic additive includes a (meth)acrylate compound having two or more (meth)acryloyl groups in one molecule and having a number average molecular weight of 1,000 or less.

Description

conductive paste

The present invention relates to a conductive paste. In particular, it relates to a conductive paste suitable for formation of internal electrode layers of multilayer ceramic capacitors.

In the manufacture of electronic components such as a multilayer ceramic capacitor (Multi-Layer Ceramic Capacitor: MLCC), a conductive paste is usually used for the formation of the electrode layer. In an example of the manufacturing method of MLCC, first, a plurality of unfired ceramic green sheets containing ceramic powder are prepared. In addition, a conductive paste for forming an internal electrode layer containing conductive powder is prepared. Next, the conductive paste is respectively applied onto the plurality of ceramic green sheets by a printing method or the like. Then, by drying the applied conductive paste, a green sheet with a conductive film is produced. Next, a plurality of the green sheets with the conductive film are laminated and pressure-bonded to each other, and then cut into a predetermined size. Then, it is integrally sintered by calcining it at a high temperature. In the above-described manner, an MLCC having a structure in which a ceramic-based dielectric layer and a conductive internal electrode layer are alternately laminated is produced.

As a prior art related to the conductive paste for forming an internal electrode layer, for example, Patent Document 1 discloses a conductive paste prepared by including a conductive powder, a resin binder, an organic additive, and an organic solvent.

[Prior Art Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2016-31912

However, in recent years, with further miniaturization and performance enhancement of various electronic devices, further miniaturization, thinning, and high density are also required for electronic components mounted in the electronic devices. From the viewpoint of satisfying the above-mentioned requirements, for example, in wafer-type MLCCs, the thickness of one layer of the internal electrode layer is thinned to the sub-micron to micron order, and the number of layers exceeds several hundreds. In the production of MLCCs in which the multi-layered layering is advanced, even when an external force is applied at the time of crimping or cutting, etc., it is necessary to prevent the conductive film from peeling off the substrate (for example, a ceramic green sheet) or a laminated structure. The laminated structure is stably maintained in the offset state. Therefore, improvement of the adhesiveness of a base material and an electroconductive film is requested|required.

The present invention has been made in view of the above-mentioned aspects, and an object thereof is to provide a conductive paste that can form a conductive film having excellent adhesion to a substrate.

The present invention provides a conductive paste for forming an electrode layer on a substrate. The conductive paste contains conductive powder, resin binder, organic additives and organic solvent. The organic additive includes a (meth)acrylate compound having two or more (meth)acryloyl groups in one molecule and having a number average molecular weight of 1,000 or less.

By using the above-mentioned conductive paste, the adhesiveness between the base material and the conductive film before firing can be improved compared with the case of using the conventional conductive paste. Thereby, peeling of a conductive film from a base material can be suppressed, and generation|occurrence|production of delamination (interlayer peeling) can be reduced. Also, for example In the production of MLCC, a plurality of green sheets with conductive films can be crimped to each other with a smaller pressure. Then, even when a plurality of green sheets with a conductive film are laminated and bonded by pressure, or when the laminated green sheets with a conductive film are cut, the laminated structure can be favorably maintained. Moreover, the handling property of paste and the workability at the time of manufacture of an electronic component can be improved.

In addition, in this specification, the so-called "(meth)acryloyl group" includes an acryl group (CH ₂ =CH-C(=O)-) and a methacryloyl group (CH ₂ =C(CH _{3 )} )-C(=O)-). In addition, in this specification, "(meth)acrylate compound" is a term containing "acrylate" and "methacrylate".

In addition, in this specification, the "number-average molecular weight" refers to measurement by gel chromatography (Gel Permeation Chromatography (GPC)) and conversion using a standard polystyrene calibration curve. The number-based average molecular weight. When the (meth)acrylate compound is a single monomer, it has the same meaning as molecular weight.

The (meth)acrylate compound may have, for example, 6 or less (meth)acryloyl groups in one molecule. The number average molecular weight of the (meth)acrylate compound may be 200 or more and 800 or less.

In a preferred aspect disclosed herein, the organic additive further includes an amine-based organic additive. Thereby, the adhesiveness of a base material and a conductive film can be improved more favorably, and the effect of this invention can be exhibited at a higher level.

In a preferred aspect disclosed herein, the (meth)acrylate compound comprises a lactone-modified (meth)acrylate compound. Thereby, it is possible to add a small amount of The adhesiveness between the base material and the conductive film is improved more favorably, and the effect of the present invention is exhibited at a high level.

In a preferable aspect disclosed here, the ratio of the organic additive is 5 mass % or less when the entire conductive paste is set to 100 mass %. Thereby, the flexibility and adhesiveness of the conductive film can be improved more stably, and the workability at the time of manufacture of electronic components can be improved more favorably. In addition, the organic additive typically burns completely during sintering of the conductive powder. Therefore, by keeping the content ratio of the organic additive low, an electrode layer excellent in electrical conductivity can be preferably realized.

In a preferred aspect disclosed herein, the resin binder includes a cellulose-based resin. The cellulose-based resin is excellent in combustion decomposability at the time of calcination. Therefore, by using the cellulose-based resin, the electrical conductivity of the electrode layer can be improved more favorably. In addition, the surface smoothness of the electrode layer can be improved more favorably.

In a preferable aspect disclosed here, the ratio of the resin binder is 1 mass % or more and 5 mass % or less when the entire conductive paste is set to 100 mass %. Thereby, the workability|operativity at the time of manufacture of an electronic component can be improved more favorably. In addition, by suppressing the content ratio of the resin binder to be low, an electrode layer excellent in electrical conductivity can be preferably realized.

The base material is, for example, a ceramic green sheet containing ceramic powder and a resin binder. In such a case, the effect of the present invention can be exhibited stably and more favorably.

The conductive paste can be suitably used for formation of internal electrode layers of a multilayer ceramic capacitor. By using the conductive paste, it is possible to stably manufacture, for example, an MLCC having several hundreds of layers.

10: Multilayer ceramic capacitors

20: Dielectric layer

30: Internal electrode layer

40: External electrode

FIG. 1 is a cross-sectional view schematically showing a multilayer ceramic capacitor according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described. Furthermore, regarding matters other than the matters specifically mentioned in this specification (for example, the composition of the conductive paste) and necessary for the implementation of the present invention (for example, the preparation method of the conductive paste, the formation method of the electrode layer, etc.), it is possible to It is grasped as a design matter of those skilled in the art based on the prior art in this field. The present invention can be implemented based on the contents disclosed in this specification and the technical common sense in the field. In addition, the expression "A-B" which shows a range in this specification means A or more and B or less.

<Conductive paste>

The conductive paste disclosed here (hereinafter, abbreviated as "paste" in some cases) is for forming an electrode layer on a base material. The conductive paste contains a conductive powder, a resin binder, an organic additive, and an organic solvent as essential constituents. Hereinafter, each component will be described in order.

<Conductive Powder>

The conductive powder contained in the paste is a component for imparting electrical conductivity to the electrode layer. It does not specifically limit as an electroconductive powder, It can select 1 type or 2 or more types suitably from the conventionally well-known electroconductive powder according to the application of a paste, etc., and can use it. A preferred example of the conductive powder includes nickel (Ni), gold (Au), silver (Ag), copper (Cu), platinum (Pt), palladium (Pd), ruthenium (Ru), rhodium (Rh), iridium (Ir), osmium (Os), aluminum (Al) and other metal monomers, and mixtures or alloy, etc. For example, in the application of forming an internal electrode layer of an MLCC, it is preferable to use a metal species whose melting temperature is sufficiently higher than the sintering temperature of the ceramic powder contained in the base material. As an example of such a metal species, the metal powder containing nickel, silver, copper, platinum, palladium, etc. is mentioned. Among them, nickel is preferred because it is inexpensive and has an excellent balance between electrical conductivity and cost. The average particle diameter of the conductive powder (value based on the number of objects observed by electron microscope. The same applies hereinafter) is preferably approximately 0.01 μm to 10 μm, typically 0.05 μm to 5 μm, for example, 0.1 μm to 0.3 μm.

The content ratio of the conductive powder to the total mass of the paste is not particularly limited, but is preferably approximately 30% by mass or more, typically 40% by mass to 95% by mass, for example, 45% by mass to 60% by mass. By satisfying this range, an electrode layer having high electrical conductivity or high density can be preferably formed. In addition, the workability of the paste and the workability at the time of printing the paste can be improved.

<Resin adhesive>

The resin binder contained in the paste is a component which imparts adhesiveness to the unfired conductive film and makes the conductive particles constituting the conductive powder and the conductive particles and the base material adhere to each other. It does not specifically limit as a resin binder, It can select 1 type or 2 or more types suitably from various resin binders previously known to be used for such an application, and it can be used suitably. As a preferable example, a cellulose-type resin, an acrylic resin, a butyral-type resin, an epoxy-type resin, a phenol-type resin, an alkyd-type resin, a rosin-type resin, etc. are mentioned. Resin binders may be, for example, linear or branched without aromaticity The aliphatic compound or the alicyclic compound containing a saturated or unsaturated carbocyclic ring without aromaticity may be an aromatic compound containing a benzene ring or the like in the molecule and having aromaticity.

In addition, the term "resin" in this specification means a polymer compound having a number average molecular weight exceeding 1,000, and is typically a polymer (polymer).

The cellulose-based resin is a term that includes the entirety of cellulose-derived compounds (cellulose derivatives) called alkyl cellulose-based resins or hydroxyalkyl cellulose-based resins in this field. Examples of cellulose-based resins include alkyl groups such as methyl, ethyl, propyl, isopropyl, and butyl groups; Acyl groups such as propionyl, butyryl, etc.; hydroxymethyl, hydroxyethyl, carboxymethyl, carboxyethyl and other substituted cellulose organic acid esters. Specific examples of cellulose-based resins include methyl cellulose (MC), ethyl cellulose (EC), hydroxyethyl cellulose (HEC), and ethyl methyl cellulose. Cellulose (ethyl methyl cellulose, EMC), hydroxyethyl methyl cellulose (hydroxyethyl methyl cellulose, HEMC), hydroxypropyl cellulose, carboxymethyl cellulose, nitrocellulose, etc. As a preferred example, ethyl groups having a structure in which the hydrogen atoms in the hydroxyl groups of cellulose as repeating constituent units are substituted with ethyl groups (CH ₃ CH ₂ groups) or hydroxyethyl groups (CH ₂ CH ₂ OH groups) can be mentioned. Cellulose resin.

Examples of the acrylic resin include a homopolymer (homopolymer) of alkyl (meth)acrylate, or an alkyl (meth)acrylate as a main monomer (50 weight based on the entire monomer). % or more components. The same applies hereinafter) and an interpolymer (copolymer) containing a copolymerizable sub-monomer in the main monomer. As a preferred example, the general formula: CH ₂ =C(R ¹ )COOR ² (here, R ¹ in the formula represents a hydrogen atom or a methyl group. In addition, R ² represents that the number of carbon atoms is 1-20 The chain-like alkyl group.) represented by the compound. The R ² preferably has 1-14 carbon atoms, more preferably 1-10 carbon atoms, such as 1-8. Specific examples of acrylic resins include polymethyl (meth)acrylate, polyethyl (meth)acrylate, polybutyl (meth)acrylate, a polymer block containing methacrylate, and acrylic acid. Block copolymers of polymer blocks of esters, etc.

The butyral-based resin is a term that includes the whole of resins called polyvinyl butyral-based resin or polyvinyl acetal-based resin in such fields. Examples of butyraldehyde-based resins include vinyl acetate homopolymers (homopolymers) and copolymers including vinyl acetate as a main monomer and a copolymerizable sub-monomer in the main monomer. (Copolymer). As a specific example of a homopolymer, polyvinyl butyral (PVB) etc. are mentioned. Specific examples of the copolymer include a butyraldehyde group, a hydroxyl group, and an acetyl group as repeating structural units in the main chain skeleton, and the degree of butyraldehyde (the ratio of acetalization with butyraldehyde) is: About 50 mol% or more, for example, 60 mol% or more of the compound and the like.

It is preferable that the resin binder contains a cellulose-based resin, for example, an ethyl cellulose-based resin, from the viewpoint of being excellent in combustion decomposability during firing or improving the surface smoothness of the electrode layer. In a preferred aspect, the content of the cellulose-based resin is approximately 50% by mass or more, preferably 80% by mass or more, when the entire resin binder is 100% by mass. In this way, it is possible to perform here at a higher level Effects of the disclosed techniques.

The number average molecular weight of the resin binder is preferably about 10,000 or more, typically 20,000 or more, for example, about 50,000 to 100,000. When the number average molecular weight is a predetermined value or more, the function as a binder can be exhibited with a small addition amount, and the adhesion between the substrate and the conductive film or the integrity of the conductive film can be improved. When the number average molecular weight is equal to or less than a predetermined value, the printability and workability of the paste can be improved.

In a preferable aspect, the resin binder does not contain a component that can generate a corrosive gas during calcination (a component that causes a corrosive gas). Specific examples of the components causing corrosion gas include sulfur components and halogen components such as fluorine and chlorine. In particular, it is preferable that the molecular structure of the resin binder is substantially composed of carbon, oxygen and hydrogen (the incorporation of unavoidable impurities can be tolerated). With such a molecular structure, no harmful gas is generated during calcination of the conductive film, and corrosion deterioration of calcination equipment and environmental load can be reduced.

The content ratio of the resin binder with respect to the conductive powder tends to be higher in general as the conductive powder becomes finer. For example, in the application of forming the internal electrode layer of MLCC, etc., in the case of using conductive powder with an average particle diameter of submicron or less, the content ratio of the resin binder is preferably 100 parts by mass of the conductive powder. Approximately 1 to 15 parts by mass, for example, 2 to 10 parts by mass. Thereby, even when the fine conductive powder is used, the adhesiveness between the base material and the conductive film or the integrity of the conductive film can be preferably ensured while suppressing the addition amount of the resin binder.

The content ratio of the resin binder to the total mass of the paste is not particularly limited, but is preferably approximately 0.1% by mass or more, typically 0.5% by mass to 10% by mass, for example 1% to 5% by mass. By satisfying the said range, the adhesiveness of a base material and a conductive film, or the integration of a conductive film can be improved more favorably. In addition, the occurrence of delamination can be highly suppressed. Furthermore, moderate viscosity can be imparted to the paste, and workability at the time of manufacture of electronic components (for example, at the time of printing the paste or at the time of laminating green sheets with a conductive film of MLCC) can be improved.

<Organic Additives>

The organic additive contained in the paste is a component for improving the adhesiveness between the base material and the conductive film. The organic additive functions as, for example, a so-called plasticizer for improving the flexibility and adhesiveness of the conductive film. The organic additive can play a role, for example, to better exert the adhesiveness of the resin adhesive. The pastes disclosed herein contain at least a prescribed (meth)acrylate compound as an organic additive.

The (meth)acrylate compound is a polyfunctional (meth)acrylate compound having two or more (meth)acryloyl groups in one molecule. The (meth)acrylate compound typically contains a (meth)acrylate monomer. The number of (meth)acryloyl groups contained in one molecule of the (meth)acrylate compound is 2 or more, typically 2 to 10, for example, 2 to 6.

As a preferred example of the (meth)acrylate compound having two (meth)acryloyl groups in one molecule, hydroxytrimethylacetate neopentyl glycol di(meth)acrylate, ethyl acetate Glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate (meth)acrylate, pentaerythritol di(meth)acrylate, dipentaerythritol di(meth)acrylate, trimethylolpropane di(meth)acrylate, polypropylene glycol di(meth)acrylate (Meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate esters, neopentyl glycol di(meth)acrylate, bis(hydroxymethyl)tricyclodecane di(meth)acrylate, bisphenol A-di(meth)acrylate, and these epoxy Bifunctional (meth)acrylates modified with cyclic lactones having lactone rings such as ethylene oxide (EO), propylene oxide (PO), or caprolactone, and the like.

As a preferred example of the (meth)acrylate compound having three (meth)acryloyl groups in one molecule, pentaerythritol tri(meth)acrylate and dipentaerythritol tri(meth)acrylate can be mentioned. , trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethyloloctane tri(meth)acrylate, tri((meth)acrylate) oxyethyl) isocyanurate, tris(2-hydroxyethyl) isocyanurate tri(meth)acrylate, sorbitol tri(meth)acrylate, and these EO or PO , or a cyclic lactone having a lactone ring such as caprolactone and a trifunctional (meth)acrylate modified with a lactone.

As a preferred example of the (meth)acrylate compound having 4 or more (meth)acryloyl groups in one molecule, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(methyl) Acrylate, dipentaerythritol hexa(meth)acrylate, tripentaerythritol hepta(meth)acrylate, tripentaerythritol octa(meth)acrylate, pentaerythritol nona(meth)acrylate, pentaerythritol ten(meth)acrylate Acrylates, and (meth)acrylates modified with lactone by cyclic lactones having a lactone ring such as EO, PO, or caprolactone, and the like.

The (meth)acrylate compound preferably has an acryl group. borrow Therefore, the effect of the technique disclosed here can be effectively exhibited with a smaller addition amount.

The (meth)acrylate compound preferably includes a lactone-modified modified (meth)acrylate compound. Thereby, the flexibility and adhesiveness of the conductive film can be improved more favorably, and the adhesion between the base material and the conductive film can be effectively improved. In addition, the lactone-modified (meth)acrylate compound is excellent in compatibility with, for example, a wide range of resin binders such as cellulose-based resins. By using one having good compatibility with the resin binder, the time-dependent change in the paste viscosity or the separation of the resin binder after gelatinization can be suppressed. Therefore, for example, when using a cellulose resin as a resin binder, it is preferable to use a lactone-modified (meth)acrylate compound as a (meth)acrylate compound. Thereby, the time-dependent change of the paste viscosity and the separation of the resin binder can be suppressed, and the paste can be used satisfactorily.

The number average molecular weight of the (meth)acrylate compound is 1000 or less, typically 100 to 1000, for example, 200 to 800. In this way, the flexibility and adhesiveness of the conductive film can be improved by making the molecular weight of the (meth)acrylate compound relatively lower than that of a polymer compound used as a binder resin, and it is effective To improve the adhesion between the substrate and the conductive film.

The molecular structure of the (meth)acrylate compound is not particularly limited as long as it has two or more (meth)acryloyl groups in one molecule and has a number average molecular weight of 1,000 or less. The (meth)acrylate compound may be, for example, a linear or branched aliphatic compound having no aromaticity, or an alicyclic compound containing a saturated or unsaturated carbocyclic ring having no aromaticity, or may be It is an aromatic compound which contains a benzene ring etc. in a molecule|numerator and has aromaticity. For example, the resin binder is aliphatic In the case of a compound, the (meth)acrylate compound preferably contains an aliphatic compound. Thereby, the flexibility or adhesiveness of the conductive film can be improved more favorably by the synergistic effect with the resin adhesive, and the adhesion between the base material and the conductive film can be effectively improved. In addition, the (meth)acrylate compound may contain a functional group other than the acryl group, for example, a hydroxyl group, a carboxyl group, or the like.

In a preferable aspect, the (meth)acrylate compound does not contain a component that can generate a corrosive gas during calcination (a component that causes a corrosive gas). Specific examples of the components causing corrosion gas include sulfur components and halogen components such as fluorine and chlorine. In particular, it is preferable that the molecular structure of the (meth)acrylate compound is substantially composed of carbon, oxygen, and hydrogen (the contamination of unavoidable impurities can be tolerated). With such a molecular structure, no harmful gas is generated during calcination of the conductive film, and corrosion deterioration of calcination equipment and environmental load can be reduced.

It is preferable that the glass transition point (Tg value based on Differential Scanning Calorimetry: DSC) of the said (meth)acrylate compound is room temperature (25 degreeC) or less. Thereby, the flexibility or adhesiveness of the conductive film can be improved more favorably, and the adhesion between the base material and the conductive film can be further improved.

The decomposition initiation temperature (value based on thermogravimetric analysis (Thermogravimetry Mass Spectrometry: TG)) of the (meth)acrylate compound is preferably approximately 100°C or higher, preferably 200°C or higher, For example, about 200℃~400℃. As a result, during the period after the conductive film is applied to the substrate and until calcination (for example, even after drying), the adhesiveness (adhesion to the substrate) can be preferably maintained to the extent that the conductive film can be adhered to the substrate. force). In addition, the (meth)acrylate The decomposition end temperature (value based on TG) of the compound is preferably approximately 1000°C or lower, typically 800°C or lower, for example, 600°C or lower. Thereby, the degreasing property can be improved, and it can be properly burnt completely at the time of calcination.

The solubility parameter (Solubility Parameter of the (meth)acrylate compound, calculated based on the Hildebrand method. The same applies hereinafter.) is preferably approximately 8 (cal/cm ³ ) ^0.5 to 13 (cal/cm ³ ). ) ^0.5 , for example, 9.5(cal/cm ³ ) ^0.5 ~12(cal/cm ³ ) ^0.5 . From the viewpoint of improving the adhesion to the base material, when the base material contains a resin binder, the difference between the solubility parameters of the resin binder contained in the base material and the (meth)acrylate compound is suitable It is about 5 (cal/cm ³ ) ^0.5 or less, for example, 3.5 (cal/cm ³ ) ^0.5 or less. Thereby, the affinity or integration of the base material and the conductive film can be improved more favorably, and the effect of the present invention can be exhibited at a higher level.

In a preferable aspect, the content ratio of the (meth)acrylate compound is approximately 50 mass % or more, preferably 80 mass % or more, when the entire organic additive is 100 mass %. Thereby, the effect of the technique disclosed here can be exhibited efficiently, suppressing the addition amount of an organic additive.

In addition to the (meth)acrylate compound, for example, for the purpose of improving the homogeneity or stability of the paste, or improving self-leveling properties, etc., the organic additives may also contain previously known compounds that can be used in such pastes. Various organic additives, such as surfactants, tackifiers, defoamers, plasticizers, leveling agents, stabilizers, antioxidants, preservatives, colorants (organic pigments, dyes), etc. As a preferable example, an alkali-based organic additive, for example, an amine-based organic additive having one or more amine groups, etc., can be mentioned. As the amine-based organic additive, for example, high carbon number of 10 or more can be mentioned. grade amine or rosin amine. In a preferred aspect, the (meth)acrylate compound and the amine-based organic additive may be included at the same time. By using these two organic additives together, the effect of the technique disclosed here can be exhibited at a higher level.

Furthermore, in such pastes, as plasticizers, phthalates such as dibutyl phthalate (DBP) and dioctyl phthalate (DOP) are generally used. class (phthalate). Phthalates are a general term for compounds in which phthalic acid and alcohol are ester-bonded. However, phthalates are environmentally hazardous substances, and their use tends to be restricted in recent years. Therefore, in a preferred aspect, it is desirable that the paste disclosed herein be constituted in a manner free of phthalates. By including the (meth)acrylate compound in the paste disclosed here, even if it does not contain phthalates, it can exhibit the effect as if it contains a plasticizer, and the flexibility of the conductive film can be improved more favorably. or stickiness.

The content ratio of the organic additive to the total mass of the paste can be appropriately changed according to the application of the paste, the properties (softness, adhesiveness, etc.) of the desired conductive film, and the like. Therefore, the content ratio of the organic additive is not particularly limited, but is preferably approximately 0.1 mass % or more, for example, 0.5 mass % or more, preferably the same as or lower than the content ratio of the resin binder, for example, 1/1 of the resin binder. 2 times or less. Specifically, it is preferably about 5 mass % or less, preferably 3 mass % or less, for example, 2 mass % or less. Thereby, the flexibility and adhesiveness of the conductive film can be improved more stably, and the workability at the time of manufacture of electronic components (for example, at the time of crimping or cutting of the laminated body at the time of manufacture of MLCC) can be improved. In addition, typically, organic additives are used in the sintering of conductive powders. burn completely. Therefore, by keeping the content ratio of the organic additive low, an electrode layer excellent in electrical conductivity can be preferably realized. Furthermore, for example, even when a thin-film-shaped electrode layer is formed, the occurrence of defects such as pores and cracks in the electrode layer can be suppressed.

<Organic solvent>

The organic solvent contained in the paste is not particularly limited as long as it can preferably dissolve or disperse the conductive powder, resin binder, and organic additives, and one or two or more of them can be appropriately selected according to the application of the paste and the like. . From the viewpoint of improving the workability during printing of the paste and the storage stability of the paste, a high-boiling organic solvent having a boiling point of approximately 200° C. or higher, for example, 200° C. to 300° C., is preferably used as the main component (50% by volume or more). ingredients.). As a preferred example, alcohol-based solvents such as dihydroterpineol and terpineol; terpene-based solvents such as isobornyl acetate; glycol-based solvents such as ethylene glycol and diethylene glycol; diethylene glycol Glycol ether-based solvents such as alcohol monoethyl ether and diethylene glycol monobutyl ether (butyl carbitol); ester-based solvents; hydrocarbon-based solvents such as toluene and xylene; in addition, mineral spirits and other organic solvents with high boiling points, etc. .

The content ratio of the organic solvent to the total mass of the paste is not particularly limited, but is preferably approximately 70% by mass or less, typically 5% by mass to 60% by mass, for example, 30% by mass to 55% by mass. By satisfying the said range, moderate fluidity|liquidity can be provided to a paste, and the workability|operativity at the time of manufacture of an electronic component (for example, at the time of printing of a paste) can be improved.

<Other ingredients>

In addition to the above-mentioned four components, the paste disclosed here may contain other additive components as needed. As an example of an additive component, inorganic additives, such as an inorganic filler, are mentioned. For example, in the application of forming an internal electrode layer of MLCC, a ceramic powder as a common material, typically barium titanate (BaTiO ₃ ) or the like can be considered.

The content ratio of the inorganic additive to the total mass of the paste is not particularly limited, but is preferably approximately 1% by mass to 20% by mass, for example, 3% by mass to 15% by mass, in applications such as forming the internal electrode layer of MLCC. When the conductive powder is set to 100 parts by mass, the content ratio of the inorganic additive with respect to the conductive powder is preferably approximately 5 parts by mass to 30 parts by mass, for example, 7 parts by mass to 25 parts by mass.

Such a paste can be prepared by weighing the said material so that it may become a predetermined content ratio, and stirring and mixing it homogeneously. For the stirring and mixing of the materials, various previously known stirring and mixing apparatuses such as roller mills, magnetic stirrers, planetary mixers, dispersers and the like can be used. The application of the paste can be performed using, for example, a printing method such as screen printing, gravure printing, offset printing, and inkjet printing, or a spray coating method. In particular, in the use of forming the internal electrode layer of MLCC, the gravure printing method capable of high-speed printing is preferred. As a base material to which a paste is provided, a ceramic green sheet, a ceramic base material, a glass base material, an amorphous silicon base material, etc. are mentioned, for example.

<use of paste>

The paste disclosed here can be preferably used in applications requiring adhesion to a substrate. As a typical application, the formation of an internal electrode layer in a laminated ceramic electronic component is mentioned. Among them, it can be preferably used for the formation of internal electrode layers of MLCCs, for example, the formation of internal electrode layers of small MLCCs with each side of 5 mm or less, especially ultra-small MLCCs with each side of 1 mm or less.

In addition, in this specification, the so-called "ceramic electronic components" means those having an amorphous The term used for the entire electronic components of a ceramic substrate (glass-ceramic substrate) or a crystalline (ie, non-glass) ceramic substrate. For example, chip inductors, high frequency filters, ceramic capacitors, low temperature fired laminated ceramic substrates (Low Temperature Co-fired Ceramics Substrate: LTCC substrates), high temperature fired laminated ceramic substrates (High Temperature Co -fired Ceramics Substrate: HTCC substrate) etc. are typical examples included in the "ceramic electronic parts" mentioned here.

Examples of the ceramic material constituting the ceramic substrate include barium titanate (BaTiO ₃ ), zirconia (ZrO ₂ ), magnesium oxide (magnesia: MgO), alumina (alumina: Al ₂ O ₃ ), oxide Oxide-based materials such as silicon (silica: SiO ₂ ), zinc oxide (ZnO), titanium oxide (titania: TiO ₂ ), cerium oxide (ceria: CeO ₂ ), and yttria (yttria: Y ₂ O ₃ ); cordierite ( _{2MgO.2Al2O3.5SiO2} ), mullite _{( 3Al2O3.2SiO2 )} , forsterite ( _{2MgO.SiO2 )} , talc ( _{MgO.SiO2 )} , silicon aluminum oxynitride (Si ₃ N ₄ -AlN-Al ₂ O ₃ ), zircon (ZrO ₂ . SiO ₂ ), ferrite iron (M ₂ O. Fe ₂ O ₃ ) and other composite oxide-based materials; silicon nitride (silicon nitride) : Nitride-based materials such as Si ₃ N ₄ ) and aluminum nitride (AlN); carbide-based materials such as silicon carbide (SiC); hydroxide-based materials such as hydroxyapatite; carbon (C ), silicon (Si) and other element-based materials; or inorganic composite materials containing two or more of these; and the like.

FIG. 1 is a cross-sectional view schematically showing the MLCC 10 . The MLCC 10 is a ceramic capacitor in which a plurality of dielectric layers 20 and internal electrode layers 30 are alternately laminated. The internal electrode layer 30 contains the calcined body of the conductive paste disclosed here. The MLCC 10 can be manufactured by the following procedure, for example.

That is, first, the ceramic green sheets are formed. In one example, a ceramic powder (eg, barium titanate, titanium oxide, etc.) as a dielectric material, a resin binder, an organic solvent, and the like are stirred and mixed to prepare a paste for forming a dielectric layer. Then, the paste is spread on a carrier sheet by a doctor blade method or the like, thereby forming a ceramic green sheet for constituting the dielectric layer 20 . This ceramic green sheet is a portion that becomes a dielectric layer after firing.

Next, a conductive paste for forming an internal electrode layer as disclosed herein is prepared. That is, at least a conductive powder, a resin binder, an organic additive, and an organic solvent are prepared, and these are stirred and mixed to prepare a conductive paste. The conductive paste is applied to the shaped ceramic green sheet in a predetermined pattern and in a desired thickness (eg, submicron to micron order). Thereby, a conductive film is formed on the ceramic green sheet. This conductive film is a portion that becomes an internal electrode layer after firing.

A predetermined number (for example, several hundreds) of ceramic green sheets with a conductive film obtained as described above are laminated and bonded by pressure, and then cut into a predetermined size to obtain an unfired laminated wafer. The unfired build-up wafer is sintered integrally by firing under appropriate heating conditions (for example, about 1000° C. to 1,300° C.). Thereby, a laminated wafer in which a plurality of dielectric layers 20 and internal electrode layers 30 are alternately laminated can be obtained. Then, the external electrode 40 is formed by applying a conductive paste for forming an external electrode to the cross section of the calcined laminated wafer and firing it. In addition, the conductive paste for external electrode formation may be the same as the conductive paste for internal electrode layer formation. MLCC 10 can thus be manufactured.

Several embodiments related to the present invention are described below, but the present invention is not intended to be limited to those shown in the embodiments.

<Preparation of conductive paste>

First, as a resin binder, the following two compounds were prepared.

． EC: ethyl cellulose

． PVB: polyvinyl butyral

In addition, as organic additives, nine types of compounds shown in Table 1 were prepared. Furthermore, organic additive A and organic additive G are polyfunctional (meth)acrylate compounds having two or more (meth)acryloyl groups in one molecule, and organic additive B to organic additive F and organic additive H are: A monofunctional (meth)acrylate compound having one (meth)acryloyl group in one molecule.

[hua 1]

Next, as shown in Table 2, conductive pastes (Examples 1 to 4, Reference Example 1 to Reference Example 11) were prepared in which the types and addition amounts of resin binders and/or organic additives were different.

Regarding Reference Example 1, no organic additive was used, and (1) nickel powder as conductive powder and (2) nickel powder as conductive powder were weighed so that the mass ratio was (1):(2):(3)=50:15:2. The barium titanate powder as a common material and (3) ethyl cellulose as a resin binder were stirred and mixed with an organic solvent so as to be 100% by mass as a whole to prepare a conductive paste.

About Examples 1 to 4 and Reference Examples 2 to 8, one or two kinds of organic additives shown in Table 2 were added, and the whole was stirred and mixed with an organic solvent so that the whole would be 100% by mass. 1 A conductive paste was prepared in the same manner.

Regarding Reference Example 9 to Reference Example 11, two resins were adhered at the ratio shown in Table 2. A conductive paste was prepared in the same manner as in Reference Example 8, except that the mixture (ethyl cellulose and polyvinyl butyraldehyde) was used in combination and stirred and mixed with the organic solvent so that the whole was 100% by mass.

<Production of laminated body>

Next, a conductive film was formed on a ceramic green sheet using the conductive paste of each example. That is, first, a ceramic green sheet mainly composed of barium titanate is prepared, and the conductive paste is applied to the surface of the ceramic green sheet by screen printing (using stainless steel (SUS) 200). Then, it dried for 10 minutes with a 100 degreeC warm air dryer, and obtained the green sheet with a conductive film. Eight sheets were produced, and one of the ceramic green sheets and the conductive film prepared separately was laminated to produce a laminate. Next, using a hot press, a pressure of 1 ton (ton) was applied from the lamination direction of the laminated body, and it was crimped under the conditions of 45° C. and 30 seconds. While gradually increasing the bonding pressure in units of 1 ton, the stacking and pressure bonding of the green sheets with the conductive film were repeatedly performed until the pressure became 8 tons. In this way, a laminate in which eight green sheets with a conductive film were pressure-bonded with different pressures was obtained. Then, when the laminated body after crimping is peeled off by hand, the pressure applied when crimping the peeled portion is referred to as the "bonding pressure". The results are shown in Table 2.

In addition, it can be said that the adhesiveness between the ceramic green sheet and the conductive film is excellent as the adhesiveness of the ceramic green sheet and the conductive film is excellent.

[Table 2]

As shown in Table 2, Reference Example 2, Reference Example 3, Reference Example 6 to Reference Example 11 had substantially the same bonding pressure as Reference Example 1 in which the organic additive was not used. In addition, in Reference Example 4 and Reference Example 5, compared with Reference Example 1 in which the organic additive was not used, the subsequent pressure was increased conversely, and the adhesiveness between the ceramic green sheet and the conductive film decreased.

With respect to these reference examples, in Examples 1 to 4, the subsequent pressure was also significantly lower than that of Reference Example 1, which did not use an organic additive, or Reference Example 9 to Reference Example 11, which used PVB as a resin binder in combination. , and the adhesion between the ceramic green sheet and the conductive film is improved.

As described above, regarding the effect of improving the adhesion between the substrate and the conductive film, It cannot be realized when a monofunctional (meth)acrylate compound having one (meth)acryloyl group in one molecule is used as an organic additive, and furthermore, the adhesiveness may decrease on the contrary. In addition, as the organic additive, when only an amine-based organic additive having no (meth)acryloyl group in the molecule is used, or in addition to the (meth)acrylate compound disclosed here, it is also used as a resin binder In the case of the butyraldehyde-based resin (PVB), the effect of improving the adhesion is small. That is, the (meth)acrylate compound as an organic additive disclosed here can be said to be a particularly advantageous material from the viewpoint of improving the adhesiveness between the base material and the conductive film.

As mentioned above, although this invention was demonstrated in detail, these descriptions are only an illustration, and this invention can make various changes in the range which does not deviate from the summary.

10‧‧‧Multilayer Ceramic Capacitors

20‧‧‧Dielectric layer

30‧‧‧Internal electrode layer

40‧‧‧External electrode

Claims (11)

A conductive paste is used for forming an electrode layer on a base material, and the conductive paste comprises: conductive powder, resin binder, organic additive and organic solvent, and the organic additive is included in one molecule and has two The above (meth)acryloyl group and the (meth)acrylate compound having a number-average molecular weight of 1,000 or less, the ratio of the resin binder is 1 mass % when the entire conductive paste is taken as 100 mass % % or more and 5 mass % or less. A conductive paste is used for forming an electrode layer on a substrate, and the conductive paste comprises: conductive powder, a resin binder, an organic additive and an organic solvent, and the resin binder comprises an ethyl cellulose resin , the organic additive includes a (meth)acrylate compound having two or more (meth)acryloyl groups in one molecule and a number average molecular weight of 1000 or less, the (meth)acrylate compound including a lactone Modified (meth)acrylate compound. The conductive paste according to claim 1 or claim 2, wherein the organic additive further contains an amine-based organic additive. The conductive paste according to claim 1, wherein the (meth)acrylate compound includes a lactone-modified (meth)acrylate compound. The conductive paste according to claim 1 or claim 2, wherein, when the entire conductive paste is taken as 100% by mass, the ratio of the organic additive It is 5 mass % or less. The conductive paste according to claim 1 or claim 2, wherein the (meth)acrylate compound has 6 or less (meth)acryloyl groups in one molecule. The conductive paste according to claim 1 or claim 2, wherein the number average molecular weight of the (meth)acrylate compound is 200 or more and 800 or less. The conductive paste according to claim 1, wherein the resin binder contains an ethyl cellulose-based resin. The conductive paste according to claim 2, wherein the ratio of the resin binder is 1 mass % or more and 5 mass % or less, when the entire conductive paste is taken as 100 mass %. The conductive paste according to claim 1 or claim 2, wherein the base material is a ceramic green sheet comprising a ceramic powder and a resin binder. The conductive paste according to claim 1 or claim 2, which is used for forming an internal electrode layer of a multilayer ceramic capacitor.

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