TW202346491A - Conductive paste, electronic component, and multilayer ceramic capacitor - Google Patents

Abstract

Provided is a conductive paste with which adhesion to a base material can be further enhanced. This conductive paste contains a conductive powder, an additive, a binder resin, and an organic solvent, wherein the conductive paste contains, as an additive, a rosin derivative that includes a hydroxyl group or an amine group.

Description

Conductive paste, electronic components, and laminated ceramic capacitors

The present invention relates to conductive pastes, electronic components, and multilayer ceramic capacitors.

As electronic devices such as mobile phones and digital devices become smaller and have higher performance, electronic components including multilayer ceramic capacitors are also expected to be smaller and have higher capacities. Multilayer ceramic capacitors have a structure in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately laminated. By thinning the dielectric layers and internal electrode layers, miniaturization and high capacity can be achieved.

A multilayer ceramic capacitor is produced as follows, for example. First, a conductive paste for internal electrodes is printed in a predetermined electrode pattern on the surface of a green sheet containing dielectric powder such as barium titanate (BaTiO ₃ ) and a binder resin, and is dried to form a dry film (conductive film). . Next, the dry film and the green sheet are laminated so as to alternately overlap each other to obtain a laminated body. Next, the laminated body is heat-pressed and integrated to form a press-bonded body. The press-bonded body is cut, and the organic binder is removed in an oxidizing gas environment or an inert gas environment, and then fired to obtain a fired wafer. Next, the external electrode slurry is applied to both ends of the fired wafer, and after firing, the surface of the external electrode is plated with nickel or the like to obtain a multilayer ceramic capacitor.

When the adhesion between the dry film and the green sheet (base material) is insufficient in the step of heating, pressing, and cutting the laminated body formed by laminating the dry film and the green sheet, the dry film ( The conductive film) is peeled off from the green sheet (base material) or the layer structure is shifted, and the resulting multilayer ceramic capacitor does not have the desired electrical characteristics.

For example, Patent Document 1 discloses a conductive slurry containing (meth)acrylic resin as a binder resin for the purpose of improving the adhesion to a ceramic green sheet. Binder resin (meth)acrylic resin, organic solvent and metal powder, wherein the glass transition temperature Tg of the (meth)acrylic resin is in the range of -60°C to 120°C, and the hydroxyl group in the molecule is in the range of 0.01% by mass to 5 The range of mass %, the acid value is in the range of 1mgKOH/g~50mgKOH/g, and the weight average molecular weight is in the range of 10000Mv~350000Mv.

Furthermore, Patent Document 2 discloses a conductive slurry for forming a conductive film on a base material that can form a conductive film having excellent adhesion to a base material. Electrode layer, the conductive slurry contains conductive powder, resin binder, organic additives and organic solvents. The above-mentioned organic additives contain two or more (meth)acrylyl groups in one molecule and a number average molecular weight of less than 1000. (meth)acrylate compounds.

Furthermore, Patent Document 3 discloses the inside of a laminated ceramic capacitor for the purpose of providing a dry film for internal electrodes that can form an internal electrode that has excellent adhesion to a dielectric layer and whose shape does not change significantly before and after heat treatment. A dry film for electrodes, which is a dry film for internal electrodes of a multilayer ceramic capacitor formed from a composition containing conductive powder and an organic binder resin, characterized in that the Vickers hardness of the dry film for internal electrodes is 47 Hv or more and Below 51Hv. [Prior technical literature] [Patent Document]

[Patent Document 1] International Publication No. 2013/187183 [Patent Document 2] Japanese Patent Application Publication No. 2018-055933 [Patent Document 3] Japanese Patent Application Publication No. 2019-121744

[Technical problem to be solved by the invention]

In recent years, from the viewpoint of improving productivity and reducing costs, in the manufacturing process of laminated ceramic capacitors, when a laminate obtained by alternately laminating dry films and ceramic green sheets is heat-pressed and bonded, the pressure may be shortened. Press time and reduce pressure when connecting.

However, when the pressing time and pressure during crimping are shortened, the conventional conductive slurry sometimes cannot obtain sufficient adhesion between the dry film and the base material, causing the position of the dry film to shift, resulting in Reduction in yield. Therefore, there is a demand for a conductive slurry that can further improve the adhesion to the base material when forming a dry film.

In view of such a situation, an object of the present invention is to provide a conductive paste that can further improve the adhesion to the base material. [Technical means]

In a first aspect of the present invention, there is provided a conductive slurry, wherein the conductive slurry contains a conductive powder, an additive, a binder resin, and an organic solvent, and as the additive, a rosin derivative having a hydroxyl group or an amine group is provided. things.

Moreover, it is desirable to contain 0.01 mass % or more and 2.0 mass % or less of the said rosin derivative with respect to the whole conductive paste. Furthermore, ideally, the temperature at which the weight loss rate of the rosin derivative reaches the maximum in thermogravimetric analysis is 200°C or higher. Furthermore, the molecular weight of the rosin derivative is preferably from 250 to 3,000. Desirably, the conductive slurry further contains an acid dispersant and/or an alkali dispersant. Furthermore, the conductive powder preferably contains at least one metal powder selected from the group consisting of Ni, Pd, Pt, Au, Ag, Cu and alloys thereof. Furthermore, the average particle diameter of the conductive powder is preferably 0.05 μm or more and 1.0 μm or less. Furthermore, preferably, the binder resin contains a butyral resin. Moreover, it is desirable that the electrically conductive slurry further contains ceramic powder. Furthermore, preferably, the ceramic powder contains barium titanate. Furthermore, the average particle diameter of the ceramic powder is preferably 0.01 μm or more and 0.5 μm or less. Moreover, it is desirable to contain 1 mass % or more and 20 mass % or less of ceramic powder with respect to the whole conductive slurry. Furthermore, the conductive slurry is ideally used for laminating internal electrodes of ceramic parts.

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

A third aspect of the present invention provides a laminated ceramic capacitor, wherein the laminated ceramic capacitor has at least a laminate in which a dielectric layer and an internal electrode layer are laminated, and the internal electrode layer is formed using the conductive paste. [Effects of the invention]

The conductive paste of the present invention can further improve the adhesion to the base material. Furthermore, in the manufacturing process of the laminated ceramic capacitor, the dry film (internal electrode layer) formed using the conductive slurry of the present invention has high adhesion to the green sheet (dielectric layer).

[Conductive paste] The conductive slurry of this embodiment contains conductive powder, ceramic powder, dispersant, binder resin, and organic solvent. Each component is described in detail below.

(Conductive powder) The conductive powder is not particularly limited, and metal powder can be used. For example, one or more powders selected from the group consisting of Ni, Pd, Pt, Au, Ag, Cu, and alloys thereof can be used. Among them, from the viewpoint of electrical conductivity, corrosion resistance, and cost, powder of Ni or its alloy (hereinafter, sometimes referred to as "Ni powder") is preferable. As the Ni alloy, for example, an alloy of at least one element selected from the group consisting of Mn, Cr, Co, Al, Fe, Cu, Zn, Ag, Au, Pt, and Pd and Ni can be used. The Ni content in the Ni alloy is, for example, 50 mass% or more, and ideally is 80 mass% or more. In addition, the Ni powder may contain approximately several hundred ppm of element S in order to suppress rapid gas generation caused by partial thermal decomposition of the binder resin during the binder removal process.

The average particle diameter of the conductive powder is preferably from 0.05 μm to 1.0 μm, and more preferably from 0.1 μm to 0.5 μm. When the average particle diameter of the conductive powder is within the above range, it can be suitably used as a slurry for internal electrodes of thinned multilayer ceramic capacitors (laminated ceramic components). The average particle diameter is a value determined by observation using a scanning electron microscope (SEM). The average particle diameter is measured for each particle diameter of a plurality of particles from an image obtained by observation with a SEM at a magnification of 10,000 times. The average value obtained by measurement (SEM average particle size).

The content of the conductive powder is preferably 30 mass % or more and less than 70 mass % with respect to the entire conductive slurry, and more preferably 40 mass % or more and 60 mass % or less. When the content of the conductive powder is within the above range, conductivity and dispersibility are excellent.

(Ceramic Powder) The ceramic powder is not particularly limited. For example, in the case of a slurry for internal electrodes of a multilayer ceramic capacitor, a conventional ceramic powder is appropriately selected depending on the type of multilayer ceramic capacitor to be used. As the ceramic powder, for example, a perovskite-type oxide containing Ba and Ti can be used, preferably barium titanate (BaTiO ₃ ).

As the ceramic powder, a ceramic powder containing barium titanate as a main component and an oxide as a sub-component can also be used. Examples of oxides include Mn, Cr, Si, Ca, Ba, Mg, V, W, Ta, Nb, and oxides of one or more rare earth elements. Furthermore, as the ceramic powder, for example, ceramic powder of a perovskite type oxide ferroelectric material in which Ba atoms of barium titanate (BaTiO ₃ ) or Ti atoms are substituted with other atoms such as Sn, Pb, Zr, etc. can be used.

When used as a conductive slurry for internal electrodes, the ceramic powder may have the same composition as the dielectric ceramic powder constituting the green sheets of the multilayer ceramic capacitor (electronic component). Accordingly, it is possible to suppress the occurrence of cracks caused by shrinkage mismatch at the interface between the dielectric layer and the internal electrode layer in the sintering step. In addition to the above, examples of such ceramic powder include ZnO, ferrite, PZT, BaO, Al ₂ O ₃ , Bi ₂ O ₃ , R (rare earth element) ₂ O ₃ , TiO ₂ , Nd ₂ O ₃ and the like. Oxide. In addition, one type of ceramic powder may be used, or two or more types may be used.

The average particle diameter of the ceramic powder is, for example, 0.01 μm or more and 0.5 μm or less, and preferably is in the range of 0.01 μm or more and 0.3 μm or less. By setting the average particle diameter of the ceramic powder to the above range, when used as a slurry for internal electrodes, sufficiently fine and thin uniform internal electrodes can be formed. The average particle diameter is a value determined by observation with a scanning electron microscope (SEM). The average particle diameter is measured from an image obtained by observation with a SEM at a magnification of 50,000 times. The particle diameter of each of the plurality of particles is measured. And the average value obtained (SEM average particle size).

The content of the ceramic powder is preferably not less than 1% by mass and not more than 20% by mass, and more preferably not less than 3% by mass and not more than 15% by mass, based on the entire conductive slurry. When the content of the ceramic powder is within the above range, dispersibility and sintering properties are excellent.

Moreover, the content of the ceramic powder is preferably 1 to 30 parts by mass, and more preferably 3 to 30 parts by mass based on 100 parts by mass of the conductive powder.

(Binder resin) As the binder resin, it is desirable to contain a butyral resin. Furthermore, when used as a slurry for internal electrodes, from the viewpoint of improving the bonding strength with the green sheet, a butyral-based resin may be included, or the butyral-based resin may be used alone. Examples of butyral-based resin include polyvinyl butyral (PVB). When the conductive slurry contains a butyral resin, the bonding strength with the green sheet can be further improved.

The content of the butyral-based resin may be, for example, 20 mass% or more, 40 mass% or more, 50 mass% or more, or 60 mass% or more relative to the entire binder resin. When the content of the butyral-based resin is in the above range, the adhesiveness is further improved, and the adhesive strength between the dry film and the green sheet (base material) is improved.

In addition, the upper limit of the content of the butyral-based resin is not particularly limited. For example, it may be 90 mass% or less or 80 mass% or less based on the entire binder resin. When the content of the butyral-based resin is within the above range, since the conductive paste has moderate hardness, problems such as the printed film not peeling off from the support film and the electrode being broken during thermocompression bonding are less likely to occur.

In addition, the weight average molecular weight (Mw) of the butyral-based resin may be 30,000 or more and 300,000 or less, may be 50,000 or more and 200,000 or less, or may be 100,000 or more and 150,000 or less. In addition, the glass transition temperature Tg of the butyral resin may be 50°C or more and 90°C or less, or may be 60°C or more and 80°C or less. By containing an additive described below together with the butyral-based resin having the above characteristics, a conductive slurry with further improved adhesion can be obtained. In addition, one type of butyral-based resin may be used alone, or two or more types may be used in combination.

Moreover, resins other than butyral resin may be contained as a binder resin. The binder resin other than the above is not particularly limited, and conventional resins can be used. Examples include cellulose-based resins such as methyl cellulose, ethyl cellulose, ethyl hydroxyethyl cellulose, and nitrocellulose. , acrylic resin, etc. Among them, from the viewpoint of solubility in a solvent, combustion decomposability, etc., it is preferable to contain a cellulose-based resin, and more preferably, it contains ethyl cellulose.

For example, when a cellulose-based resin is contained as a binder resin, the weight average molecular weight (Mw) may be 10,000 to 300,000, may be 30,000 to 250,000, or may be 50,000 to 250,000. Below 200,000. In addition, the hydroxyl value of the cellulose-based resin is not particularly limited, but is preferably 0.1 mgKOH/g or more and 15 mgKOH/g or less, more preferably 0.5 mgKOH/g or more and 7 mgKOH/g or less, further preferably 1.5 mgKOH/g or more and 3 mgKOH/g. /g or less. In addition, the cellulose-based resin may be contained individually by one type or two or more types. When the content of the cellulose-based resin is large, the glass transition temperature Tg described below may increase and the adhesion may decrease. Therefore, an ideal combination contains a butyral resin.

In addition, when the binder resin contains a cellulose-based resin and a butyral-based resin, from the viewpoint of improving the adhesion, relative to the total content of the cellulose-based resin and the butyral-based resin (100 mass % ), may contain 20% by mass or more of butyral-based resin, may contain 40% by mass or more, may exceed 50% by mass, or may contain 60% by mass or more. When the contents of both resins are within the above ranges, the adhesiveness may be further improved, and the adhesive strength between the dry film and the green sheet (base material) may be improved. In addition, the upper limit of the butyral-based resin content is not particularly limited, and may be less than 100% by mass, 90% by mass or less, or 80% by mass or less. When the contents of the two resins are within the above ranges, the conductive paste can have moderate hardness, be less likely to cause problems such as the printed film not peeling off from the support film and the electrode being broken during thermocompression bonding, and have high adhesion to the green sheet. Stickiness.

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 7% by mass or less based on the entire conductive slurry. When the content of the binder resin is within the above range, conductivity and dispersibility are excellent.

The content of the binder resin is preferably not less than 1 part by mass and not more than 20 parts by mass, and more preferably not less than 1 part by mass and not more than 14 parts by mass based on 100 parts by mass of the conductive powder.

(organic solvent) The organic solvent is not particularly limited, and a conventional organic solvent capable of dissolving the binder resin can be used. Examples of the organic solvent include terpene-based solvents, acetate-based solvents, ether-based solvents, and ketone-based solvents.

Examples of terpene-based solvents include terpineol, dihydroterpineol, dihydroterpineol acetate, and the like.

Examples of acetate-based solvents include isobornyl acetate, isobornyl propionate, isobornyl butyrate, isobornyl isobutyrate, etc., ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether, etc. Butyl ether acetate, diethylene glycol monoethyl ether acetate, dipropylene glycol methyl ether acetate, 3-methoxy-3-methylbutyl acetate, 1-methoxypropyl-2- Glycol ether acetates such as acetate, propylene glycol diacetate, 1,4-butanediol diacetate, 1,3-butanediol diacetate, 1,6-hexanediol diethyl Acid esters such as glycol diacetates, cyclohexanol acetate, etc.

Examples of ether solvents include propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, and propylene glycol monobutyl ether, diethylene glycol mono-2-ethylhexyl ether, and ethylene glycol. Glycol ethers such as mono-2-ethylhexyl ether, diethylene glycol monohexyl ether, ethylene glycol monohexyl ether, dipropylene glycol methyl-n-propyl ether, dipropylene glycol methyl-n-butyl ether, dipropylene glycol Dimethyl ether etc.

Examples of ketone solvents include methyl isobutyl ketone, diisobutyl ketone, and the like. When a ketone solvent is contained, the viscosity can be adjusted without impairing the dispersibility, and the drying property can be improved.

The organic solvent preferably contains at least one selected from the group consisting of terpineol, dihydroterpineol, dihydroterpineol acetate, propylene glycol monobutyl ether, and diethylene glycol monobutyl ether acetate. . By containing the above-mentioned organic solvent, the compatibility with the binder resin is excellent, and the dispersibility of the filler is also excellent.

The content of the organic solvent (total) is preferably 20 mass% or more and 60 mass% or less, and more preferably 25 mass% or more and 45 mass% or less based on the total amount of the conductive slurry. When the content of the organic solvent is within the above range, conductivity and dispersibility are excellent.

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

In addition, one type of organic solvent may be used, or two or more types of organic solvents may be used. For example, when two or more types of organic solvents are contained, the organic solvent may be selected from the group consisting of terpineol, dihydroterpineol, dihydroterpineol acetate (DHTA), propylene glycol monobutyl ether, and diethylene glycol. At least one of the group consisting of monobutyl ether acetate, and a hydrocarbon solvent. Moreover, you may contain at least one selected from methyl isobutyl ketone and diisobutyl ketone together with the said organic solvent.

Examples of hydrocarbon-based solvents include solvents containing tridecane, nonane, cyclohexane, etc., mineral spirits, naphthenic solvents, and the like. Among them, it is desirable to contain mineral spirits. The content of the hydrocarbon-based solvent may be 10% by mass or more and 50% by mass or less, or may be 20% by mass or more and 40% by mass or less based on the entire organic solvent.

(Additive) (a) Rosin derivatives The conductive slurry according to this embodiment contains a rosin derivative having a hydroxyl group or an amino group (hereinafter, also simply referred to as a "rosin derivative") as an additive.

Here, rosin derivatives refer to compounds derived from rosin acid and the like. Examples thereof include rosin acid and dehydroabietic acid, dihydroabietic acid, tetrahydroabietic acid, disabietic acid, and neorosin as derivatives thereof. Compounds with a rosin skeleton such as acid, pimaric acid-type resin acids such as L-piramic acid, hydrogenated rosin obtained by hydrogenating the same, and disproportionated rosin obtained by disproportionating the same. In addition, the rosin skeleton may contain a structure in which two or more rosins are bonded, or may contain a rosin ester structure.

As a result of intensive research, the inventors of the present invention found that a conductive slurry containing a rosin derivative having a hydroxyl group or an amine group among rosin derivatives can improve the dry film and ceramic green sheet formed from the conductive slurry. (dielectric layer) adhesion.

The detailed reason for this is not yet clear, but it is considered that, for example, by adding the above-mentioned rosin derivative, the interaction between resins is hindered, thereby softening the dry film appropriately, and the dry film that becomes easily deformed due to softening is considered to be unblocked. Interacting resins, etc. tend to cause entanglement at the bonding interface, so the adhesion between the dry film and the ceramic green sheet (dielectric layer) is improved.

The additive is not particularly limited as long as it is a rosin derivative having a hydroxyl group or an amino group. However, from the viewpoint of improving adhesion, it is preferably a rosin derivative having a hydroxyl group, more preferably one or two hydroxyl groups, and further It is ideal to have two hydroxyl groups. The hydroxyl value of the rosin derivative may be, for example, 10 mgKOH/g or more, 20 mgKOH/g or more, 50 mgKOH/g or more, or 100 mgKOH/g or more. In addition, the upper limit of the hydroxyl value is not particularly limited, but is, for example, 200 mgKOH/g or less. In addition, the rosin derivative preferably does not have an acidic group such as a carboxyl group. The acid value of the rosin derivative may be, for example, 20.0 mgKOH/g or less, or 5.0 mgKOH/g or less.

The temperature at which the weight loss rate of the rosin derivative reaches the maximum in thermogravimetric analysis (maximum thermal decomposition temperature) may be, for example, 200°C or higher, or may be 220°C or higher, and is preferably 250°C or higher. When the boiling point or thermal decomposition temperature is within the above range, delamination and cracking of the laminated body can be suppressed. In addition, the upper limit of the boiling point or thermal decomposition temperature is not particularly limited, but may be 450°C or lower, or 420°C or lower, for example.

In addition, the maximum thermal decomposition temperature can be measured by thermogravimetry (TG). Specifically, when the weight loss at this time is measured using a thermal decomposition weight measuring device (STA25000REGULUS manufactured by NETZSCH) in a nitrogen gas environment, the temperature is increased from 20°C to 550°C at a temperature increase rate of 5°C/min. The temperature at which the differential heating reduction reaches the maximum is taken as the decomposition temperature.

The molecular weight of the rosin derivative is preferably 250 or more and 3000 or less, more preferably 250 or more and 2000 or less, further preferably 250 or more and 1200 or less. When the molecular weight of the rosin derivative is within the above range, the adhesion to the ceramic green sheet (dielectric layer) is further improved.

Furthermore, the content of the rosin derivative is preferably 0.01% by mass or more and 1.0% by mass or less based on the entire conductive slurry. When the content of the rosin derivative is within the above range, the adhesion between the dry film and the ceramic green sheet (dielectric layer) is improved. In addition, from the viewpoint of further improving the adhesion, the lower limit of the content of the rosin derivative may be 0.05% by mass or more or 0.1% by mass or more based on the entire conductive slurry.

The upper limit of the content of the rosin derivative may be 2 mass% or less, 1.8 mass% or less, 1.5 mass% or less, 1.0 mass% or less, or less than 1.0 mass%. When the content of the rosin derivative exceeds 1% by mass, although it has high adhesion, thermal decomposition may occur and gas may be generated when the pressure-bonded body of the laminate of the dry film and the ceramic green sheet is debonded. status. The content of the rosin derivative can be appropriately adjusted within the above range according to the use environment and the like. In addition, the upper limit of the rosin derivative may be 0.7% by mass or less, or may be 0.4% by mass or less. In the conductive paste of this embodiment, high adhesion can be achieved even if the upper limit of the rosin derivative is the above range.

In addition, the content of the rosin derivative can be appropriately set according to the type and content of the above-mentioned binder resin. For example, the content of the rosin derivative can be set according to the content of the butyral resin. For example, 10 parts by mass or more and 90 parts by mass or less of the rosin derivative may be contained based on 100 parts by mass of the butyral-based resin, or it may be 10 parts by mass or more and 60 parts by mass or less, or it may be 10 parts by mass or more and 60 parts by mass or less. 50 parts by mass or less.

(b) Dispersant When the conductive slurry contains a dispersant, the dispersibility of the conductive powder and ceramic powder can be improved. The dispersant may include, for example, an acidic dispersant, an alkali dispersant, a nonionic dispersant, an amphoteric dispersant, etc., and preferably at least one of an acidic dispersant and an alkali dispersant, and more preferably an acidic dispersant. Dispersants. In addition, the above-mentioned dispersing agents may be used alone or in combination of two or more types.

The acid-based dispersant may include carboxylic acid-based dispersants such as higher fatty acids, polycarboxylic acid-based dispersants, phosphoric acid-based dispersants, acid-based dispersants such as polymer surfactants, etc., and preferably contains polycarboxylic acid-based dispersants. At least one of an acid dispersant and a phosphoric acid dispersant. In addition, the polycarboxylic acid-based dispersant may be a comb-type carboxylic acid having a comb-type structure.

The higher fatty acid may be an unsaturated carboxylic acid or a saturated carboxylic acid, and is not particularly limited. Examples thereof include stearic acid, oleic acid, myristic acid, palmitic acid, linoleic acid, lauric acid, linolenic acid, and other carbonic acids. Higher fatty acids with atomic number 11 or more. Among them, oleic acid or stearic acid is ideal.

Examples of the acid-based dispersant include oleylsarcosine, which is a compound of glycine and oleic acid, and an alkyl group of an amide compound using a higher fatty acid such as stearic acid or lauric acid instead of oleic acid. Monoamine salt type.

Moreover, from the viewpoint of further improving the separation-inhibiting effect of the conductive powder and the ceramic powder, a dicarboxylic acid may be contained. Dicarboxylic acids are carboxylic acids with two carboxyl groups (COO-groups). In addition, the average molecular weight of the dicarboxylic acid is not particularly limited, and may be, for example, 200 or more and 1,000 or less.

Examples of the alkali dispersant include aliphatic amines such as laurylamine, rosinamine, cetylamine, myristamine, and stearylamine. When the conductive slurry contains the above-mentioned acid-based dispersant and alkali-based dispersant, the dispersibility may be more excellent and the viscosity stability over time may also be excellent.

The dispersant is contained, for example, from 0.01% by mass to 3% by mass relative to the entire conductive slurry. The upper limit of the content of the dispersant may be 2 mass% or less, 1 mass% or less, or 0.5 mass% or less. When the content of the dispersant is within the above range, the dispersibility of the conductive slurry can be improved, or sheet erosion and green sheet peeling defects can be suppressed.

(c) Other additives The conductive paste of this embodiment may contain other additives other than the above-mentioned components as needed. As other additives, conventionally known additives such as defoaming agents, plasticizers, surfactants, and thickeners can be used.

(Conductive paste) The manufacturing method of the conductive paste according to this embodiment is not particularly limited, and conventionally known methods can be used. The conductive slurry can be produced by, for example, stirring and kneading the above-mentioned components using a three-roll mill, a ball mill, a mixer, or the like.

The conductive slurry according to this embodiment can improve the adhesion between the dry film and the green sheet by containing the above-mentioned rosin derivative. As one reason for the improvement in adhesion, as mentioned above, it is considered that the rosin derivative hinders The interaction between resins causes the dry film to moderately soften (lower the glass transition temperature Tg) and become easily deformed.

For example, when components other than the conductive powder and ceramic powder in the conductive slurry are dried at 120° C. for 40 minutes to prepare a dried body (sample for evaluation) from which the organic solvent is removed, the glass transition of the dried body The temperature Tg is preferably lower than the glass transition temperature Tg' of a dried body formed under the same conditions except that the rosin derivative is not included. The above-mentioned rosin derivative may be a rosin derivative that lowers Tg by 5°C or more or 9°C or more compared with Tg'. For example, the glass transition temperature Tg of the dried body may be 65°C or lower, or may be 60°C or lower. In addition, the lower limit of the glass transition temperature Tg is, for example, 30° C. or higher. When the range of the glass transition temperature Tg is within the above range, high adhesion can be achieved. Furthermore, when the above-mentioned rosin derivative is used as an additive, high adhesion is achieved even when the lower limit of the glass transition temperature Tg exceeds 55°C.

In addition, when the conductive paste contains two or more resins as binder resins, a plurality of glass transition temperatures Tg may be measured depending on the resins contained. However, the glass transition temperature of the evaluation sample in this specification Temperature Tg represents the glass transition temperature Tg in the lowest temperature region. In addition, the glass transition temperature Tg of the above-mentioned dried body (sample for evaluation) can be measured by the method described in the Examples.

Furthermore, when the conductive slurry is applied to the surface of the base material and dried at 75° C. for 20 minutes to form a dry film, the Vickers hardness of the dry film surface at room temperature is preferably 10 or less. In addition, the lower limit of the Vickers hardness (room temperature) may be, for example, 3.5 or more, 5 or more, or 8 or more.

Moreover, the Vickers hardness of the dry film surface at 60° C. is preferably 8 or less, and preferably 9 or less. In addition, the lower limit of Vickers hardness (60° C.) is, for example, 3 or more, or may be 5 or more. In addition, when measuring the Vickers hardness (60°C) of a dry film, it is ideal to condition the measured dry film by leaving it at 60°C for 3 minutes in advance.

The conductive paste can be suitably used for electronic components such as multilayer ceramic capacitors, and is particularly suitably used as a paste for internal electrodes of multilayer ceramic capacitors.

[Multilayer Ceramic Capacitor] Hereinafter, embodiments of the multilayer ceramic capacitor of the present invention will be described with reference to the drawings. In the drawings, the figures may be represented in a schematic manner or the scale may be changed as appropriate. Moreover, the position, direction, etc. of a component are demonstrated suitably with reference to the XYZ orthogonal coordinate system shown in FIG. 1 etc. In this XYZ orthogonal coordinate system, the X direction and the Y direction are horizontal directions, and the Z direction is the vertical direction (up and down direction).

A in FIG. 1 and B in FIG. 1 are diagrams showing the multilayer ceramic capacitor 1 . The multilayer ceramic capacitor 1 includes a ceramic multilayer body 10 and external electrodes 20 in which dielectric layers 12 and internal electrode layers 11 are alternately laminated.

Hereinafter, a method of manufacturing a multilayer ceramic capacitor using the above-mentioned conductive paste as a paste for internal electrodes will be described. First, conductive paste is printed on a ceramic green sheet and dried to form a dry film. A plurality of ceramic green sheets having the dry films on their upper surfaces are laminated by pressure bonding to obtain a laminated body, and then the laminated body is fired to integrate them, whereby the internal electrode layer 11 and the dielectric layer 12 are alternately produced. The ceramic laminated body 10 is made of ground layers. Thereafter, the laminated ceramic capacitor 1 is manufactured by forming a pair of external electrodes 20 at both ends of the ceramic laminated body 10 . This is explained in more detail below.

First, a green sheet which is an unfired ceramic sheet is prepared. Examples of the green sheet include a slurry for a dielectric layer obtained by adding a binder resin such as polyvinyl butyral and a solvent such as terpineol to a raw material powder of a predetermined ceramic such as barium titanate and adding it to PET. A green sheet obtained by coating a supporting film such as a film into a sheet shape and drying it to remove the solvent. In addition, the thickness of the dielectric layer composed of the green sheet is not particularly limited, but from the viewpoint of the requirement for miniaturization of the multilayer ceramic capacitor, it is preferably 0.05 μm or more and 3 μm or less.

Next, a plurality of sheets are prepared, in which the conductive paste is printed and applied on one side of the green sheet and dried to form a dry film on one side of the green sheet. In addition, from the viewpoint of the requirement of thinning the internal electrode layer 11, the thickness of the dry film formed of the conductive slurry is preferably 1 μm or less after drying.

Next, the green sheet is peeled off from the support film, laminated so that the green sheet and the dry film formed on one surface of the green sheet are alternately arranged, and then heated and pressurized to obtain a laminated body. In addition, it may be configured such that protective ceramic green sheets to which conductive slurry is not applied are further disposed on both sides of the laminate.

Next, the laminated body is cut into a predetermined size to form a green wafer, and then the green wafer is subjected to a binder removal process and fired in a reducing gas environment to produce a laminated ceramic fired body (ceramic laminated body 10 ). In addition, the gas environment in the binder removal treatment is ideally an atmosphere or an N ₂ gas atmosphere. The temperature when performing the binder removal process is, for example, 200°C or more and 400°C or less. Moreover, it is desirable to set the holding time at the above temperature during the binder removal process to 0.5 hours or more and 24 hours or less. In addition, in order to suppress oxidation of the metal used in the internal electrode layer, the firing is performed in a reducing gas environment, and the temperature during firing of the laminated body is, for example, 1000°C or more and 1350°C or less. The holding time is, for example, 0.5 hours or more and 8 hours or less.

By firing the green wafer, the organic binder in the ceramic green wafer is completely removed, and the ceramic raw material powder is fired to form the ceramic dielectric layer 12 . In addition, the organic carrier in the dried film is removed, and the nickel powder or the alloy powder containing nickel as the main component is sintered or melted to integrate, thereby forming the internal electrode layer 11, and further forming a plurality of alternating sheets of the dielectric layer 12 and the internal electrode layer 11. A laminated ceramic fired body made of layers of ground. In addition, from the viewpoint of bringing oxygen into the interior of the dielectric layer to improve reliability and suppress re-oxidation of the internal electrodes, the fired laminated ceramic fired body may be subjected to an annealing treatment.

Next, a pair of external electrodes 20 is provided on the produced laminated ceramic fired body, whereby the laminated 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 a material of the external electrode 20 , for example, copper, nickel, or an alloy thereof can be suitably used. In addition, as electronic components, electronic components other than multilayer ceramic capacitors may be used. [Example]

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

[Evaluation method] (Evaluation of tightness) Conductive slurry (sample) was applied to the surface of a previously prepared green sheet containing barium titanate and polyvinyl butyral to form a conductive slurry film with a wet film thickness of 35 μm. The obtained green sheet and the sheet composed of the conductive slurry film for internal electrodes formed on the surface were dried at 75° C. for 20 minutes to form a dry film on the green sheet. The dried sheet (dried film-green sheet) was overlapped with another green sheet so that the surfaces coated with the conductive slurry were sandwiched between the green sheets, and then the drying process was performed for 20 seconds at a temperature of 40°C and a pressure of 20 MPa. Press and produce a laminated body (for evaluation).

The obtained laminated body was cut into 1 cm squares, and both sides of the laminated body were placed on the clamps of a tensile testing machine (AGS-50NX, manufactured by Shimadzu Corporation) using tape, and a tensile test was performed. The force at breakage (the force at which the dry film is peeled off from the green sheet) is recorded at a test speed of 20 mm/min. The force at breakage in Comparative Example 1 was taken as 100%, and each force at breakage was evaluated in %.

(hardness measurement) Using a micro-Vickers hardness tester (manufactured by Shimadzu Corporation, HMV-G21DT), under the condition of a test force of 98 mN, at n = 5 points, the conductive film formed under the same conditions as the adhesion evaluation was evaluated. The surface of the green sheet (dry film side) of the slurry film (dry film) is measured, and the Vickers hardness of the surface is measured, and the average value is calculated. The hardness measurement is performed by attaching the sample to a glass substrate, placing it on a heated workbench as the sample stage of the hardness tester, and conducting it at unheated room temperature (25°C) and heated to 60°C. In addition, when measuring the Vickers hardness (60°C), the dry film measured in advance was left at 60°C for 3 minutes to adjust the state, and then the measurement was performed while maintaining the state after heating at 60°C.

(Measurement of glass transition temperature Tg) Among the components contained in the conductive slurry, components other than conductive powder and ceramic powder, namely, ethyl cellulose resin and polyvinyl butylidene, were weighed in the same amount as those contained in the conductive slurry. The aldehyde resin, additives, and organic solvent were mixed using a rotation-revolution mixer (ARE-310 manufactured by THINKY) at 2000 rpm for 4 minutes, and then the resulting liquid (mixture) was applied to PET with a wet film thickness of 254 μm using an applicator. The film was dried at 120° C. for 40 minutes to obtain a sample for evaluation. Furthermore, organic solvents in the mixture are removed during drying.

Using a differential scanning calorimeter (NETZSCH Japan Co., Ltd., DSC3100), 10 mg of the dried sample for evaluation was placed in an aluminum pan, and the temperature was increased at 10°C/min under a nitrogen gas flow of 100 mL/min. The temperature was increased from 0° C. to 140° C., and the glass transition temperature Tg on the low-temperature region side was calculated from the peak of the obtained endothermic curve.

(Thermal decomposition temperature measurement) The thermal decomposition temperature of the additive used in the conductive slurry was measured using a thermal decomposition gravimeter (STA25000REGULUS manufactured by NETZSCH). The temperature measurement gas environment is nitrogen, and the measurement temperature range is from 20°C to 550°C at a temperature rise rate of 5°C/min. The temperature at which the differential heating loss reaches the maximum, that is, the temperature at which the weight reduction rate in the thermogravimetric analysis reaches the maximum, is defined as the thermal decomposition temperature (maximum thermal decomposition temperature).

[Materials used] (Conductive powder) As the conductive powder, Ni powder (SEM average particle size: 0.2 μm) was used.

(Ceramic Powder) As the ceramic powder, barium titanate (BaTiO ₃ , SEM average particle diameter: 0.10 μm) was used.

(Binder resin) As the binder resin, polyvinyl butyral resin (PVB) and ethylcellulose resin (EC) are used.

(dispersant) In the Examples and Comparative Examples, a polycarboxylic acid-based dispersant that is an acid-based dispersant was used as a commonly contained dispersant (additive).

(Additive) As rosin derivatives, the compounds shown in Table 1 below were used. In addition, the structures represented by formulas (1) and (2) in Table 1 represent structures of the following formulas (1) and (2). Moreover, the molecular weight (weight average molecular weight) of the rosin derivative (C) is approximately 1,000.

〔Table 1〕

〔Chemical 1〕

〔Chemical 2〕

As a comparative example, the following additives were used. Additive a: polycarboxylic acid with polyoxyalkylene as graft chain Additive b: oxyethylene laurylamine (polyetheramine) Additive c: dicarboxylic acid

(organic solvent) As organic solvents, dihydroterpineol (DHT) and mineral spirits (MSA) are used.

[Example 1] Add 49 mass% of conductive powder, 12 mass% of ceramic powder, 0.15 mass% of acid dispersant, 0.3 mass% of rosin derivative (A), and 2.5 mass% of binder resin (PVB:EC=7:3 (mass ratio) ) and the balance of the organic solvent (DHT:MSA=60:40 (mass ratio)), so that the total amount is 100% by mass, and these materials are mixed to prepare a conductive slurry. Table 2 shows the content of each material in the conductive paste and the evaluation results.

[Examples 2 to 5, Comparative Examples 1 to 7] As shown in Table 2, except having changed the rosin derivative (A) (additive) to the type and content of the additive shown in Table 2, a conductive slurry was prepared and evaluated in the same manner as in Example 1. Table 2 shows the content of each material in the conductive paste and the evaluation results.

〔Table 2〕

(evaluation results) The conductive pastes of Examples 1 to 5 containing a rosin derivative having an amino group or a hydroxyl group are compared with the conductive pastes of Comparative Example 1 containing no rosin derivative, or Comparative Examples 2 to 7 containing other additives. Than, the adhesion is improved.

Furthermore, the glass transition temperatures of the conductive pastes of Examples 1 to 5 were all 64°C or less, and the glass transition temperature of Comparative Example 1 was 69°C. Therefore, in the conductive pastes of Examples 1 to 5, it was confirmed that the glass transition temperature was lowered by 5° C. or more compared to Comparative Example 1. [Industrial Applicability]

When the conductive slurry of the present invention is used for the formation of internal electrodes of a multilayer ceramic capacitor, a highly reliable multilayer ceramic capacitor can be obtained with high productivity. Therefore, the conductive slurry of the present invention is particularly suitable for use as an internal electrode of a laminated ceramic capacitor, which is a chip component of electronic equipment such as mobile phones and digital devices that are being miniaturized.

In addition, the technical scope of the present invention is not limited to the forms described in the above-mentioned embodiments and the like. One or more of the requirements described in the above-mentioned embodiments and the like may be omitted. In addition, the requirements described in the above-mentioned embodiments and the like can be combined appropriately. In addition, as long as the laws and regulations permit, the disclosures of all documents cited in the above-described embodiments and the like are incorporated as part of the description of this specification. In addition, as long as permitted by laws and regulations, the contents of Japanese Patent Application No. 2022-052667, which is a Japanese patent application, are incorporated into the description of this specification.

Embodiments of the present invention may include the following configurations.

[1] A conductive slurry characterized by containing conductive powder, additives, binder resin and organic solvent, As the aforementioned additive, a rosin derivative having a hydroxyl group or an amino group is included.

[2] The conductive paste according to [1], which contains 0.01% by mass or more and 2.0% by mass or less of the rosin derivative relative to the entire conductive paste.

[3] The conductive slurry according to [1] or [2], wherein the temperature at which the weight loss rate of the rosin derivative reaches the maximum in thermogravimetric analysis is 200°C or higher.

[4] The conductive slurry according to any one of [1] to [3], wherein the molecular weight of the rosin derivative is 250 or more and 3000 or less.

[5] The conductive slurry according to any one of [1] to [4], wherein the conductive slurry further contains an acidic dispersant and/or an alkali dispersant.

[6] The conductive slurry according to any one of [1] to [5], wherein the conductive powder contains Ni, Pd, Pt, Au, Ag, Cu and alloys thereof. At least one metal powder.

[7] The conductive slurry according to any one of [1] to [6], wherein the conductive powder has an average particle diameter of 0.05 μm or more and 1.0 μm or less.

[8] The conductive slurry according to any one of [1] to [7], wherein the binder resin contains a butyral resin.

[9] The conductive slurry according to any one of [1] to [8], wherein the conductive slurry further contains ceramic powder.

[10] The conductive slurry according to [9], wherein the ceramic powder contains barium titanate.

[11] The conductive slurry according to [9] or [10], wherein the ceramic powder has an average particle diameter of 0.01 μm or more and 0.5 μm or less.

[12] The conductive slurry according to any one of [9] to [11], which contains 1 mass % or more and 20 mass % or less of the ceramic powder with respect to the entire conductive slurry.

[13] The conductive slurry according to any one of [1] to [12], wherein the conductive slurry is used for laminating internal electrodes of ceramic parts.

[14] An electronic component, characterized in that the electronic component is formed using the conductive paste according to any one of [1] to [13].

[15] A laminated ceramic capacitor, characterized in that the laminated ceramic capacitor has at least a laminated body in which a dielectric layer and an internal electrode layer are laminated, The internal electrode layer is formed using the conductive paste described in [13].

1: Multilayer ceramic capacitor 10: Ceramic laminated body 11: Internal electrode layer 12: Dielectric layer 20:External electrode 21:External electrode layer 22:Electroplating layer

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

1: Multilayer ceramic capacitor

10: Ceramic laminated body

11: Internal electrode layer

12: Dielectric layer

20:External electrode

21:External electrode layer

22:Electroplating layer

Claims (15)

A conductive slurry characterized by containing conductive powder, additives, binder resin and organic solvent, As this additive, a rosin derivative having a hydroxyl group or an amino group is included. The conductive slurry according to claim 1, which contains 0.01 mass % or more and 2.0 mass % or less of the rosin derivative relative to the entire conductive slurry. The conductive slurry as claimed in claim 1, wherein the temperature at which the weight loss rate of the rosin derivative reaches the maximum in thermogravimetric analysis is above 200°C. The conductive slurry according to claim 1, wherein the molecular weight of the rosin derivative is 250 or more and 3000 or less. The conductive slurry according to claim 1, wherein the conductive slurry further contains an acid dispersant and/or an alkali dispersant. The conductive slurry according to claim 1, wherein the conductive powder contains at least one metal powder selected from the group consisting of Ni, Pd, Pt, Au, Ag, Cu and alloys thereof. The conductive slurry according to claim 1, wherein the conductive powder has an average particle size of 0.05 μm or more and 1.0 μm or less. The conductive slurry according to claim 1, wherein the binder resin contains a butyral resin. The conductive slurry according to claim 1, wherein the conductive slurry further contains ceramic powder. The conductive slurry according to claim 9, wherein the ceramic powder contains barium titanate. The conductive slurry according to claim 9, wherein the average particle size of the ceramic powder is 0.01 μm or more and 0.5 μm or less. The conductive slurry according to claim 9, which contains 1 mass % or more and 20 mass % or less of the ceramic powder with respect to the entire conductive slurry. The conductive slurry according to claim 1, wherein the conductive slurry is used for laminating internal electrodes of ceramic parts. An electronic component characterized by being formed using the conductive paste according to any one of claims 1 to 13. A laminated ceramic capacitor, characterized in that the laminated ceramic capacitor has at least a laminated body in which a dielectric layer and an internal electrode layer are laminated, The internal electrode layer is formed using the conductive paste described in Claim 13.