Conductive paste composition

Abstract

To provide a conductive paste composition that has low viscosity applicable to various printing methods in a high shear rate region and a middle shear rate region, while having a high viscosity suitable for a low shear rate region.SOLUTION: A conductive paste composition includes conductive powder, ceramic powder, binder resin, and organic solvent. The binder resin is adsorbed onto the conductive powder and / or the ceramic powder such that the adsorption amount of the conductive powder and / or the ceramic powder is 0.2 mg / m2 or more and 15 mg / m2 or less per surface area.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to a conductive paste composition used to form internal electrodes that constitute, for example, multilayer ceramic capacitors. [Background technology]

[0002] As electronic devices such as mobile phones and digital devices become lighter, thinner, and smaller, there is a demand for chip components such as multilayered ceramic capacitors (hereafter referred to as "MLCC") to be smaller, have higher capacitance, and perform better. The most effective way to achieve this is to make the internal electrode layers and dielectric layers thinner and create more layers.

[0003] MLCCs are generally manufactured as follows. First, to form a dielectric layer, a dielectric green sheet is formed using a dielectric ceramic powder such as barium titanate (BaTiO3) as the main component, and a binder resin made of a butyral resin such as polyvinyl butyral or an acrylic resin. A conductive paste composition in which a conductive powder is dispersed in an organic vehicle containing a binder resin and an organic solvent is printed in a predetermined pattern on the surface of the dielectric green sheet, and the conductive paste composition is dried to remove the organic solvent, forming a dry film that becomes an internal electrode layer. The dielectric green sheets on which the dry film is formed are stacked in multiple layers and integrated by heat and pressure bonding, and then cut to obtain chips, and the chips are subjected to a binder removal treatment at 500°C or less in an oxidizing atmosphere or an inert atmosphere. After that, the chips after the binder removal treatment are heated and fired at about 1300°C in a reducing atmosphere so as not to oxidize the internal electrode layers, and the internal electrode layers and the dielectric layers are integrated to obtain fired chips. Finally, a paste for external electrodes is applied to the fired chip and fired, and then the resulting external electrodes are plated with nickel or the like to complete the MLCC.

[0004] In the firing process, the temperature at which dielectric ceramic powder such as barium titanate starts to sinter and shrink is about 1200°C, which is significantly different from the temperature of 400°C to 500°C at which conductive powder such as nickel starts to sinter and shrink. This makes it easy for structural defects such as delamination (interlayer peeling) and cracks to occur. In particular, the more the number of layers increases or the thinner the ceramic dielectric layers become with the trend toward smaller size and higher capacity, the more pronounced the occurrence of structural defects becomes.

[0005] As a countermeasure, a ceramic powder mainly composed of perovskite oxide such as barium titanate or strontium zirconate, which is similar to the composition of the dielectric ceramic constituting the dielectric layer, is usually added to the conductive paste composition for the internal electrode in order to control the sintering and shrinkage of the internal electrode layer at least up to the temperature at which the dielectric layer starts to sinter and shrink. The addition of the ceramic powder to the conductive paste is intended to suppress the deterioration of electrical properties such as an increase in dielectric loss caused by structural defects that occur when the constituent elements of the main component of the dielectric layer and the constituent elements of the dielectric powder contained in the electrode paste are significantly different, that is, to control the sintering behavior of the conductive powder such as nickel powder and compensate for the mismatch of the sintering shrinkage behavior of the internal electrode layer and the dielectric layer.

[0006] A conductive paste composition for an internal electrode is generally obtained by dispersing a conductive powder, a ceramic powder, and a dispersant in an organic vehicle obtained by dissolving a binder resin in an organic solvent, and adjusting the viscosity with the organic solvent. Ethyl cellulose or the like is generally used as the binder resin constituting this organic vehicle, and terpineol or the like has been used as the organic solvent (see JP 2018-168238 A).

[0007] In addition, the conductive paste may be applied by various printing methods such as gravure printing, offset printing, inkjet printing, and screen printing, not limited to internal electrodes. Therefore, the conductive paste composition is required to have rheological properties suitable for each printing method. For example, International Publication WO2014 / 073530 and Japanese Patent Application Laid-Open No. 2018-107089 discuss compositions of conductive paste compositions suitable for the rheological properties of gravure printing, Japanese Patent Application Laid-Open No. 2017-084588 discuss compositions suitable for the rheological properties of inkjet printing, and International Publication WO2014 / 104053 discuss compositions suitable for the rheological properties of screen printing.

[0008] Furthermore, conductive pastes are required to be non-sagging when applied by various printing methods, and to suppress changes in viscosity during storage, thereby preventing separation of components due to viscosity changes and even the settling of some of the components. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2018-168238 A [Patent Document 2] International Publication No. WO2014 / 073530 [Patent Document 3] JP 2018-107089 A [Patent Document 4] JP 2017-084588 A [Patent Document 5] International Publication No. WO2014 / 104053 Summary of the Invention [Problem to be solved by the invention]

[0010] Thus, the conductive paste composition for the internal electrode is required to have rheological properties and anti-sagging properties suitable for various printing methods, particularly high-speed gravure printing, and further, to have little change in viscosity during storage. In terms of simultaneously having all these properties, there is still room for improvement in the conventional conductive paste composition described above.

[0011] In other words, an object of the present disclosure is to provide a conductive paste composition that can control the viscosity in the low shear rate region, has little viscosity change during storage, and has rheological properties and anti-sagging properties suitable for a variety of printing methods, particularly gravure printing, i.e., has a suitably low viscosity in the high shear rate region and medium shear rate region, and has a moderately high viscosity in the low shear rate region. [Means for solving the problem]

[0012] The conductive paste composition of one embodiment of the present disclosure includes a conductive powder, a ceramic powder, a binder resin, and an organic solvent. Alternatively, the conductive paste composition of one embodiment of the present disclosure includes a conductive powder, a ceramic powder, a dispersant, a binder resin, and an organic solvent.

[0013] In particular, in the conductive paste composition according to one embodiment of the present disclosure, the binder resin has an adsorption amount per surface area of ​​the conductive powder and / or the ceramic powder of 0.2 mg / m 2 More than 15mg / m 2 The adsorption amount per surface area of ​​the conductive powder and / or the ceramic powder is 1.0 mg / m 2 More than 10mg / m 2 The range is preferably 2.0 mg / m or less. 2 More than 5.0mg / m 2 It is more preferable that the range is as follows:

[0014] In the conductive paste composition of one embodiment of the present invention, the organic solvent can be composed of a mixed solvent containing a first solvent made of a terpene-based solvent, a second solvent made of a petroleum-based hydrocarbon, and a third solvent different from the first solvent and the second solvent.

[0015] In this case, the third solvent is preferably at least one selected from β-ketoester solvents, 2-ethylhexyl acetate, furfuryl acetate, 1,6-hexanediol acetate, diethylene glycol butyl ether acetate (BCA), linalyl acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether, diethylene glycol monomethyl ether, and propylene glycol butyl ether (PNB).

[0016] It is preferable to use the β-ketoester solvent. In this case, it is preferable that the β-ketoester solvent is a liquid at 25° C. and has a boiling point at 1013 hPa of 100° C. or higher and 270° C. or lower.

[0017] The β-ketoester solvent is preferably at least one selected from methyl acetoacetate, ethyl acetoacetate, propyl acetoacetate, isopropyl acetoacetate, allyl acetoacetate, n-butyl acetoacetate, isobutyl acetoacetate, sec-butyl acetoacetate, tert-butyl acetoacetate, amyl acetoacetate, isoamyl acetoacetate, n-hexyl acetoacetate, n-octyl acetoacetate, methyl 3-oxopentanoate, ethyl 3-oxopentanoate, methyl 3-oxohexanoate, ethyl 3-oxohexanoate, methyl 3-oxoheptanoate, and ethyl 3-oxoheptanoate.

[0018] The β-ketoester solvent is more preferably one selected from methyl 3-oxohexanoate, ethyl 3-oxohexanoate, methyl 3-oxopentanoate, and ethyl 3-oxopentanoate.

[0019] The mixed solvent preferably contains 40% by mass or more and 60% by mass or less of the first solvent, 10% by mass or more and 40% by mass or less of the second solvent, and more than 0% and 50% by mass or less of the third solvent.

[0020] In the conductive paste composition according to the aspect of the present invention, it is preferable that the conductive powder is at least one selected from nickel, copper, gold, silver, platinum, palladium, and alloys thereof.

[0021] In the conductive paste composition according to one aspect of the present invention, the conductive powder preferably has an average particle size of 0.05 μm or more and 0.5 μm or less.

[0022] In the conductive paste composition according to one aspect of the present invention, the content of the conductive powder is preferably 30% by mass or more and 70% by mass or less with respect to the total amount of the conductive paste composition.

[0023] In the conductive paste composition according to one aspect of the present invention, the content of the binder resin is preferably 1% by mass or more and 5% by mass or less with respect to the total amount of the conductive paste composition.

[0024] In the conductive paste composition according to one aspect of the present invention, the ceramic powder is preferably barium titanate.

[0025] In the conductive paste composition according to one aspect of the present invention, the ceramic powder preferably has an average particle size of 0.01 μm or more and 0.2 μm or less.

[0026] In the conductive paste composition according to one aspect of the present invention, the content of the ceramic powder is preferably 3 parts by mass or more and 25 parts by mass or less with respect to 100 parts by mass of the conductive powder.

[0027] In the conductive paste composition according to one embodiment of the present invention, when a dispersant is contained as an optional component, the content of the dispersant is preferably 0.01 parts by mass or more and 2.0 parts by mass or less per 100 parts by mass of the conductive powder. Effect of the Invention

[0028] The conductive paste composition according to one embodiment of the present disclosure has a controllable viscosity in the low shear rate region, has little change in viscosity during storage, has a suitable low viscosity in the high shear rate region and the medium shear rate region, and has a suitable high viscosity in the low shear rate region. Thus, the conductive paste composition according to one embodiment of the present disclosure has properties suitable for various printing methods, particularly gravure printing, and can therefore be suitably used as a conductive paste for internal electrodes of MLCCs formed by various printing methods. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] 1. Conductive paste composition The conductive paste composition according to an embodiment of the present disclosure includes a conductive powder, a dielectric ceramic powder, a binder resin, and an organic solvent. More specifically, the conductive paste composition is a paste in which the conductive powder and the dielectric ceramic powder are dispersed in an organic vehicle in which the binder resin is dissolved in an organic solvent.

[0030] (1) Conductive powder In this embodiment, the type of conductive powder constituting the conductive paste is not particularly limited. For the internal electrodes of multilayer components such as multilayer ceramic capacitors (MLCCs), for example, metal powders such as nickel (Ni), copper (Cu), gold (Au), silver (Ag), platinum (Pt), palladium (Pd), or alloys thereof can be used. In particular, for the internal electrodes of highly multilayered MLCCs in which the number of electrode layers is increased in order to increase capacity, it is preferable to use nickel or copper, which are cost-effective among these.

[0031] The particle size of the conductive powder is not particularly limited, but in the case of conductive powder for the internal electrodes of MLCCs with high stacking and high capacity, the average particle size is preferably in the range of 0.05 μm to 0.5 μm. The average particle size of the conductive powder is defined as the arithmetic mean value of the maximum diameters of 200 or more conductive powders randomly selected from an observation image at a magnification of 10,000 times obtained by a scanning electron microscope (FE-SEM). If the average particle size of the conductive powder exceeds 0.5 μm, it becomes difficult to make the MLCC thin. If the average particle size of the conductive powder is less than 0.05 μm, the surface activity of the conductive powder becomes too high, and problems such as the conductive paste composition not being able to obtain appropriate viscosity characteristics and the conductive paste being likely to deteriorate during long-term storage may occur.

[0032] The content of the conductive powder in the conductive paste composition is preferably 30% by mass or more and 70% by mass or less based on the total amount of the conductive paste composition. If the content of the conductive powder is less than 30% by mass, the ability to form the internal electrode layer during firing is reduced, making it difficult for the MLCC to obtain a predetermined capacitance. If the content of the conductive powder is more than 70% by mass, it becomes difficult to make the internal electrode film thin. The content of the conductive powder is more preferably 40% by mass or more and 60% by mass or less based on the total amount of the conductive paste composition.

[0033] (2) Ceramic powder When ceramic powder is added to the conductive paste as a sintering inhibitor, it can usually be selected from perovskite oxides such as barium titanate (BaTiO3) and perovskite oxides with various additives added. The ceramic powder preferably has the same composition as the ceramic powder used as the main component of the dielectric layer green sheet for MLCC, or a similar composition. As the ceramic powder, ceramic powders manufactured by various manufacturing methods such as solid phase method, hydrothermal synthesis method, alkoxide method, and sol-gel method can be used. If necessary, the ceramic powder can be added to the conductive paste in the form of a ceramic slurry that has been dispersed and pulverized by a device such as a bead mill or a high-pressure homogenizer.

[0034] The average particle size of the ceramic powder is preferably in the range of 0.01 μm to 0.2 μm. If the average particle size of the ceramic powder exceeds 0.2 μm, the density of the internal electrode layer (dry film) decreases. In the internal electrode layer, the ceramic powder is filled into the gaps of the structure formed by stacking the approximately spherical particles that constitute the conductive powder. If the average particle size of the ceramic powder exceeds 0.2 μm, it becomes difficult to enter between the contact points of the approximately spherical particles that constitute the conductive powder, making it difficult to obtain the desired density of the internal electrode layer, and further, the effect of delaying the sintering start temperature of the internal electrode layer formed by the conductive paste to the sintering start temperature of the dielectric layer becomes weaker.

[0035] If the average particle size of the ceramic powder falls below 0.01 μm, it becomes difficult to obtain the sintering delay effect of the internal electrode layer formed by the conductive paste, and structural defects such as delamination and cracks may occur in laminated components such as MLCCs. Furthermore, the density of the internal electrode layer may decrease, and the ceramic powder may form agglomerated powder, making it difficult to thin the dielectric layer, which may impair the reliability of the capacitor (decreased insulation resistance, increased short-circuit rate, etc.).

[0036] In this example, the average particle size of the ceramic powder, like that of the conductive powder, is defined as the arithmetic mean value of the maximum diameters of 200 or more randomly selected conductive powder particles measured from an image observed at a magnification of 10,000 times using a field emission scanning electron microscope (FE-SEM), unless otherwise specified.

[0037] The content of the ceramic powder is preferably 3 parts by mass or more and 25 parts by mass or less per 100 parts by mass of the conductive powder. If the content of the ceramic powder is less than 3 parts by mass, for example, the sintering of the conductive powder such as nickel powder cannot be controlled, and the mismatch of the sintering shrinkage behavior of the internal electrode layer and the dielectric layer becomes significant, which may cause structural defects such as delamination and cracks in laminated components such as MLCCs. If the content of the ceramic powder exceeds 25 parts by mass, for example, the thickness of the dielectric layer expands due to sintering of the internal electrode layer with the ceramic particles in the dielectric layer, causing a deviation in composition, which may have an adverse effect on electrical properties such as a decrease in dielectric constant.

[0038] (3) Binder resin The binder resin and the organic solvent constitute an organic vehicle. More specifically, the binder resin is dissolved in the organic solvent to prepare an organic vehicle, and the conductive powder and the dielectric ceramic powder are dispersed in the organic vehicle to obtain the conductive paste composition.

[0039] In the conductive paste composition of this example, the binder resin is required to have an adsorption functional group for the conductive powder or ceramic powder. For example, a hydroxy group, a carboxy group, or an amino group can be an adsorption functional group. As long as this condition is satisfied, any binder resin that can impart good viscosity and coating film forming ability (adhesion to the dielectric green sheet) to the conductive paste composition can be used as the binder resin without any particular limitation. For example, binder resins mainly made of cellulose-based resins, acetal-based resins, acrylic-based resins, epoxy-based resins, phenol-based resins, alkyd-based resins, rosin-based resins, etc. can be used. Examples of the cellulose-based resin include ethyl hydroxyethyl cellulose and ethyl cellulose. Examples of the acetal-based resin include polyvinyl butyral. Examples of the acrylic-based resin include polymethacrylate and polyacrylate. Of these, it is preferable to use ethyl hydroxyethyl cellulose, ethyl cellulose, and polyvinyl butyral from the viewpoints of solubility in solvents and combustion decomposition properties.

[0040] The content of the binder resin is not particularly limited, but is preferably 1% by mass or more and 30% by mass or less in the organic vehicle. By setting the content of the binder resin in this range, it is possible to prepare an organic vehicle with an appropriate viscosity. The content of the binder resin in the organic vehicle is more preferably 5% by mass or more and 20% by mass or less. In addition, the content of the binder resin relative to the total amount of the conductive paste composition is preferably 1% by mass or more and 5% by mass or less. If it is less than 1% by mass, the strength of the internal electrode layer decreases, or the adhesion between the electrode pattern part of the conductive paste and the dielectric sheet becomes poor during lamination, making them easy to peel off. On the other hand, if it exceeds 5% by mass, the binder removal property deteriorates due to the increased resin content, which is not preferable.

[0041] (4) Organic solvents The organic solvent, together with the binder resin, constitutes an organic vehicle. The organic solvent disperses the conductive powder, ceramic powder, and binder resin, and adjusts the viscosity of the conductive paste composition to an appropriate range so that it can be printed in a predetermined pattern. The organic solvent is removed during the process of forming the internal electrode layer (dried film).

[0042] In the conductive paste composition of this example, the organic solvent is preferably a mixed solvent containing a first solvent made of a terpene solvent, a second solvent made of a petroleum-based hydrocarbon, and a third solvent different from the first and second solvents. The organic solvent of this example has high solubility of the binder resin in the organic vehicle and does not cause the viscosity of the conductive paste composition to change over time. Therefore, the conductive paste composition is less likely to cause sheet attack during coating, and can achieve rheological properties that are applicable to various printing methods, that is, a sufficiently low and appropriate viscosity.

[0043] The first solvent is a good solvent for the binder resin, and may be, for example, a terpene-based solvent. As the terpene-based solvent, for example, at least one selected from the group consisting of terpineol and dihydroterpineol may be used. It is more preferable to use dihydroterpineol. Dihydroterpineol is a hydrogenated terpineol, which is less susceptible to reactions such as oxidation and is more stable than terpineol.

[0044] The second solvent is a poor solvent for the binder resin, and examples thereof include petroleum-based hydrocarbons. Examples of solvents made of petroleum-based hydrocarbons include gasoline, kerosene, coal tar naphtha, petroleum ether, petroleum naphtha, petroleum benzine, turpentine oil, and mineral spirits. Of these, it is preferable to use mineral spirits. Examples of mineral spirits include mineral thinner, petroleum spirits, white spirits, and mineral turpentine. More specifically, there are LAWS (Low Aromatic White Spirit) and HAWS (High Aromatic White Spirit).

[0045] The third solvent is added to increase the solubility of the binder resin and to make the conductive paste composition suitable for various printing methods, particularly suitable for gravure printing, with a low viscosity. In the conductive paste composition of this example, a β-ketoester solvent, other ethers, acetates, etc. are used as the third solvent. In particular, a β-ketoester solvent is preferable as the third solvent in that it makes it possible to achieve both the viewpoint of making sheet attack less likely to occur when forming the internal electrode layer in the conductive paste composition and the viewpoint of making the viscosity appropriate and low.

[0046] Specifically, the β-ketoester solvent has a structure represented by the following formula 1. R-CO-CH2-CO-O-R' (Equation 1) However, when R is CH3-, R' is -CH3, -CH2CH3, -CH2CH2CH3, -CH(CH3)2, -CH2CH2CH2CH3, -CH2CH(CH3)2, -CH(CH3)CH2CH3, -C(CH3)3, -CH2CH2CH2CH2CH3, -CH2CH2CH(CH3)2, -CH2CH2CH2CH2CH2CH3, or -CH2CH2CH2CH2CH2CH2CH2CH2CH2CH3; when R is CH3CH2-, R' is -CH3 or -CH2CH3; and when R is CH3CH2CH2-, R' is -CH3 or -CH2CH3.

[0047] As the β-ketoester solvent, it is preferable to use one that is liquid at room temperature (25° C.) and has a boiling point at normal pressure (1013 hPa) of 100° C. or more and 270° C. or less. Examples of such β-ketoester solvents include methyl acetoacetate, ethyl acetoacetate, propyl acetoacetate, isopropyl acetoacetate, allyl acetoacetate, n-butyl acetoacetate, isobutyl acetoacetate, sec-butyl acetoacetate, tert-butyl acetoacetate, amyl acetoacetate, isoamyl acetoacetate, n-hexyl acetoacetate, n-octyl acetoacetate, methyl 3-oxopentanoate, ethyl 3-oxopentanoate, methyl 3-oxohexanoate, ethyl 3-oxohexanoate, methyl 3-oxoheptanoate, and ethyl 3-oxoheptanoate.

[0048] Of the β-ketoester solvents, it is preferable to use methyl 3-oxohexanoate, ethyl 3-oxohexanoate, methyl 3-oxopentanoate, or ethyl 3-oxopentanoate.

[0049] In this example, other ethers and acetates applicable as the third solvent include 2-ethylhexyl acetate, furfuryl acetate, 1,6-hexanediol acetate, diethylene glycol butyl ether acetate (BCA), linalyl acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether, diethylene glycol monomethyl ether, propylene glycol butyl ether (PNB), etc. More preferably, 1,6-hexanediol acetate, diethylene glycol butyl ether acetate (BCA), propylene glycol butyl ether (PNB), etc. can be mentioned.

[0050] In the conductive paste composition of this example, the blending amount of each organic solvent in the mixed solvent is preferably 40% by mass or more and 60% by mass or less for the first solvent, 10% by mass or more and 40% by mass or less for the second solvent, and more than 0% and 50% by mass or less for the third solvent. It is more preferable to set the first solvent to 45% by mass or more and 55% by mass or less, the second solvent to 10% by mass or more and 30% by mass or less, and the third solvent to 5% by mass or more and 30% by mass or less, and in this case, it is even more preferable to set the third solvent to 5% by mass or more and 26% by mass or less.

[0051] The content of the organic solvent is not particularly limited, but is preferably set so that the content of the conductive powder relative to the total amount of the conductive paste composition is 30% by mass or more and 70% by mass or less, more preferably set so that it is 30% by mass or more and 60% by mass or more, and even more preferably set so that it is 35% by mass or more and 55% by mass or more. The content of the organic solvent is preferably 40 parts by mass or more and 100 parts by mass or less, more preferably 65 parts by mass or more and 95 parts by mass or less, relative to 100 parts by mass of the conductive powder. When the content of the organic solvent is within the above range, a conductive paste composition having excellent conductivity and dispersibility and low viscosity applicable to various printing methods can be obtained.

[0052] (5) Dispersants In the conductive paste composition of this example, the dispersant is an optional component. When a dispersant is further added, the dispersant is added to the organic vehicle together with the conductive powder and the dielectric ceramic powder. The dispersant has the function of maintaining the dispersion state of the conductive powder in the conductive paste composition and suppressing the viscosity change of the conductive paste composition over time. In the conductive paste composition of this example, the type of dispersant is not particularly limited. For example, cationic dispersants, anionic dispersants, nonionic dispersants, amphoteric surfactants, polymer dispersants, etc. can be used. Among these, it is preferable to use an anionic dispersant. Examples of anionic dispersants include carboxylic acid dispersants, phosphoric acid dispersants, and phosphate dispersants. These dispersants can be used alone or in combination of two or more. Anionic dispersants have a large adsorption force to the surface of the conductive powder, and therefore contribute to increasing the dispersibility of inorganic components through their surface modification action, and therefore also have the function of improving the smoothness of the coating film and the density of the internal electrode layer.

[0053] The average molecular weight of the dispersant is preferably 200 or more and 20,000 or less. More preferably, the average molecular weight of the dispersant is 300 or more and 10,000 or less. If the average molecular weight of the dispersant is less than 200, the particles constituting the conductive powder may not obtain sufficient electrostatic repulsion, and the dispersibility of the conductive powder and the storage stability of the conductive paste composition may decrease. Usually, the dispersant is adsorbed on the particle surface to form an adsorption layer of the dispersant, and electrostatic repulsion and steric repulsion are imparted to the particles, thereby obtaining a conductive paste composition with excellent dispersibility. However, it is considered that the particles aggregate with each other due to collisions between the particles over time, which overcomes the repulsion of the adsorption layer. Therefore, taking this point into consideration, the average molecular weight of the dispersant is preferably 200 or more. If the average molecular weight of the dispersant exceeds 20,000, the compatibility with the binder resin and the organic solvent may decrease, or the particles may aggregate, which may cause the dispersibility of the conductive powder and the storage stability of the conductive paste composition to decrease. In addition, the viscosity of the conductive paste composition may increase.

[0054] The content of the dispersant is preferably 0.01 to 2.0 parts by mass, more preferably 0.2 to 1.0 parts by mass, relative to 100 parts by mass of the conductive powder. If the content of the dispersant is less than 0.01 parts by mass relative to 100 parts by mass of the conductive powder, sufficient dispersibility tends to be difficult to obtain. On the other hand, if the content exceeds 2.0 parts by mass, problems such as poor drying properties and a decrease in the density of the internal electrode layer may occur.

[0055] (6) Other additives In order to adjust the viscosity or impart a suitable viscosity to the conductive paste composition in this example, an organic solvent or binder resin different from the organic solvent or binder resin described above may be added depending on the purpose. As the additional organic solvent or binder resin, it is preferable to use an organic solvent or binder resin having a known structure that is basically applicable to the conductive paste composition. In this case, it is preferable to add the organic solvent or binder resin within the range of the content of the organic solvent or binder resin in the conductive paste composition. Furthermore, if necessary, known additives that are applicable to the conductive paste composition, such as an antifoaming agent, a plasticizer, a thickener, or a chelating agent, may also be added.

[0056] (7) Viscosity The conductive paste composition of this example was subjected to a shear rate of 100 sec at 25°C. -1 The viscosity at a shear rate of 100 sec is less than 1.5 Pa·s. -1 The viscosity at a shear rate of 100 sec is preferably less than 1.4 Pa·s, more preferably less than 1.2 Pa·s, and even more preferably less than 1.0 Pa·s. -1 When the viscosity at a shear rate of 100 sec is less than 1.5 Pa s, the conductive paste composition can be applied to various printing methods. -1 When the viscosity at shear rate is less than 1.4 Pa·s, the composition can be suitably used for high-speed printing methods such as gravure printing. -1The lower limit of the viscosity is not particularly limited, but from the viewpoint of applicability to various printing methods, it is preferably 0.1 Pa·s or more, and more preferably 0.6 Pa·s or more.

[0057] The conductive paste composition of this example was subjected to a shear rate of 10,000 sec at 25°C. -1 The viscosity at a shear rate of 10,000 sec is preferably less than 0.26 Pa·s, and more preferably less than 0.24 Pa·s. -1 When the viscosity at shear rate is within the above range, the conductive paste composition can be applied to various printing methods, and can be particularly suitably used in high-speed printing methods such as gravure printing. -1 The lower limit of the viscosity is not particularly limited, but from the viewpoint of applicability to various printing methods, it is preferable that the lower limit of the viscosity is 0.05 Pa·s or more.

[0058] The conductive paste composition of this example has a shear rate of 0.025 sec at 25°C. -1 The viscosity at a shear rate of 0.025 sec is preferably 30 Pa·s or more and less than 350 Pa·s, more preferably 40 Pa·s or more and less than 250 Pa·s, and even more preferably 50 Pa·s or more and less than 150 Pa·s. -1 When the viscosity at 30 Pa s or more is 30 Pa s or more, the change in viscosity during storage can be reduced, and separation of the conductive powder and the ceramic powder due to a decrease in viscosity, and further sedimentation of the conductive powder and the ceramic powder, can be sufficiently suppressed. In addition, when the conductive paste composition is used in various printing methods, it becomes possible to prevent the conductive paste composition from dripping after the flow of the conductive paste composition stops.

[0059] The viscosity of the conductive paste composition can be measured, for example, by a viscometer such as a rheometer.

[0060] (8) Amount of binder resin adsorbed In the conductive paste composition of this example, the amount of binder resin adsorbed to the conductive powder and / or ceramic powder is 0.2 mg / m2 per surface area of ​​the conductive powder and / or ceramic powder. 2 More than 15mg / m 2 The range is preferably 1.0 mg / m or less. 2 More than 10mg / m 2 More preferably, the range is 2.0 mg / m or less. 2 More than 5.0mg / m 2 The range is as follows. When the conductive paste composition is applied to a printing method such as gravure printing, the conductive paste composition is required to have low viscosity in the high shear rate region and the medium shear rate region, and moderately high viscosity in the low shear rate region, that is, high shear thinning property. By setting the adsorption amount of the binder resin within this range, it is possible to impart high shear thinning property to the conductive paste composition.

[0061] The term "high shear thinning property" refers to a conductive paste composition that exhibits high shear rate, for example, a shear rate (shear rate) of 10,000 sec at 25°C. -1 , and moderate shear rates, e.g., shear rate of 100 sec at 25°C -1 At low shear rates, for example, 0.025 sec at 25°C, the viscosity is low enough for a variety of printing methods. -1In this case, the viscosity is moderately high. When the amount of adsorption of the binder resin is within this range, a network structure composed of the conductive powder, ceramic powder, and binder resin in the conductive paste composition is appropriately formed in the low shear rate region. Therefore, the viscosity change during storage can be reduced, and it is possible to suppress separation of the conductive powder and the ceramic powder due to a decrease in viscosity, and further, to suppress sedimentation of the conductive powder and the ceramic powder. On the other hand, when a high shear rate is applied during printing, the network structure collapses, the viscosity of the conductive paste composition is sufficiently reduced, smooth printing on the substrate is possible, and it is considered that it is possible to prevent the conductive paste composition from sagging after the flow of the conductive paste composition stops.

[0062] In this example, by applying the above-mentioned composition of the organic solvent, the viscosity of the conductive paste composition in the high shear rate region and the medium shear rate region can be sufficiently reduced, and the viscosity in the low shear rate region can be adjusted to an appropriate range. In addition, in the conductive paste composition, the binder resin tends to be adsorbed to the surface of the conductive powder or the ceramic powder. On the other hand, in the conductive paste composition, the organic solvent is also considered to be adsorbed to the surface of the conductive powder or the ceramic powder in competition with the binder resin. Therefore, the amount of the binder resin adsorbed changes depending on the composition of the organic solvent used. By utilizing this mechanism, it is considered that it is possible to form an appropriate network structure in the conductive paste composition by adjusting the amount of the binder resin adsorbed to the conductive powder and / or the ceramic powder.

[0063] The amount of adsorbed binder resin can be measured by treating the conductive paste composition with a centrifuge and quantitatively analyzing the unadsorbed binder resin contained in the resulting supernatant using pyrolysis gas chromatography mass spectrometry.

[0064] The amount of binder resin adsorbed can be adjusted, for example, by changing the type and composition of the organic solvent according to the content (charged amount) of the binder resin.

[0065] (9) Method for producing conductive paste composition The conductive paste composition of this example can be produced by preparing an organic solvent so that the blending amounts of the first solvent, the second solvent, and the third solvent are within an appropriate range, mixing the binder resin and the organic solvent to obtain an organic vehicle, and stirring and mixing the conductive powder and the ceramic powder, or the conductive powder, the ceramic powder, and the dispersant, using a known means such as a three-roll mill, a ball mill, a mixer, etc., to disperse them in the organic vehicle. In this case, if a dispersant is applied to the surface of the conductive powder in advance, the aggregation of the conductive powder is suppressed, making it easier to obtain a uniform conductive paste composition.

[0066] The binder resin may be dissolved in a portion of the organic solvent and then added to the remaining organic solvent together with the conductive powder and ceramic powder, or together with the conductive powder, ceramic powder, and dispersant.

[0067] (10)Applications The conductive paste composition of this example can be suitably used for electronic components such as MLCC. The MLCC has a dielectric layer formed of a dielectric green sheet and an internal electrode layer formed of the conductive paste composition. In this MLCC, it is preferable that the dielectric ceramic powder contained in the dielectric green sheet and the ceramic powder contained in the conductive paste composition are the same powder.

[0068] The multilayer ceramic device manufactured using the conductive paste composition of this example has improved dispersion stability and sufficient suppression of separation between the conductive powder and the ceramic powder, so that even if the thickness of the dielectric green sheet is, for example, 3 μm or less, it is possible to suppress sheet attack, in which the organic solvent (mixed solvent) in the conductive paste composition swells or dissolves the binder resin in the dielectric green sheet, and has a low viscosity that can be applied to various printing methods. Therefore, it is possible to form internal electrode layers using various printing methods without causing sheet attack. EXAMPLES

[0069] The present disclosure will be described in more detail below using examples and comparative examples, but the present disclosure is not limited to these examples and comparative examples.

[0070] (Paste Viscosity) The viscosity of the conductive paste composition was measured using a rheometer (Anton Paar MCR501 Rheometer) at 25°C and a shear rate of 100 sec -1 Viscosity at 25°C and shear rate of 10,000 sec -1 Viscosity at 25°C and shear rate of 0.025sec -1 The viscosity at each point was measured.

[0071] (Measurement of the amount of adsorption of binder resin) The amount (g) of the binder resin adsorbed to the conductive powder and / or ceramic powder was estimated by treating the conductive paste composition with a centrifuge and quantitatively analyzing the unadsorbed binder resin contained in the resulting supernatant using a pyrolysis chromatography analysis system consisting of a combination of a pyrolysis chromatograph (Shimadzu Corporation, GC-2010plus) and a pyrolysis furnace (Frontier Labs, EGA / PY-3030D) connected to a mass spectrometer (Shimadzu Corporation, GCMS-QP2010ultra).

[0072] In addition, the specific surface area (m 2 / g) was calculated, and the total specific surface area (m 2 ) was calculated, and the amount of binder resin adsorbed per surface area of ​​the conductive powder and ceramic powder (mg / m) was calculated from the total specific surface area and the amount of binder resin adsorbed to the conductive powder and / or ceramic powder. 2 ) was sought.

[0073] Example 1 100g of nickel powder with an average particle size of 0.2μm was prepared as the conductive powder, and 25g of barium titanate powder with an average particle size of 0.05μm was prepared as the ceramic powder. Next, 1.4g of ethyl cellulose as a binder resin and 3.9g of polyvinyl butyral were dissolved in 39.2g of dihydroterpineol as a first solvent to prepare an organic vehicle. Ethyl cellulose has hydroxyl and / or carboxyl groups as an adsorptive functional group. Nickel powder and ceramic powder were added to this organic vehicle, pre-mixed, and then mixed with a three-roll mill. 14.8g of mineral spirit as a second solvent and 20.0g of propyl acetoacetate as a third solvent, which is a type of β-ketoester solvent, were added to the obtained mill base, and mixed at 2000 rpm for 4 minutes using a planetary mixer to obtain a conductive paste composition.

[0074] The mass ratio of dihydroterpineol (first solvent), mineral spirits (second solvent), and propyl acetoacetate (third solvent) in the organic solvent was 53 / 20 / 27. In addition, the barium titanate powder was 25 parts by mass, the binder resin was 5.3 parts by mass, and the mixed solvent was 74 parts by mass relative to 100 parts by mass of nickel powder. That is, the conductive paste composition contained 49% by mass of nickel powder, 12.2% by mass of barium titanate powder, 2.6% by mass of binder resin, and 36.2% by mass of organic solvent.

[0075] Conductive paste composition shear rate at 25°C: 100 sec -1 The viscosity is 1.0 Pa·s, the shear rate is 10,000 sec at 25°C. -1 The viscosity at 0.2 Pa·s and the shear rate at 25°C are 0.025 sec -1 The viscosity at 1000 g / cm2 was 50 Pa s. The amount of binder resin adsorbed per surface area of ​​the conductive powder and ceramic powder in the obtained conductive paste composition was 2.7 mg / m2. 2 It was.

[0076] Example 2 A conductive paste composition was prepared in the same manner as in Example 1, except that the third solvent was changed to 2-ethylhexyl acetate, and the paste viscosity was measured and the sheet attack was evaluated.

[0077] Conductive paste composition shear rate at 25°C: 100 sec -1 The viscosity is 1.2 Pa·s at 25°C and a shear rate of 10,000 sec -1 The viscosity at 0.2 Pa·s and the shear rate at 25°C are 0.025 sec -1 The viscosity at 1000 g / cm2 was 310 Pa s. The amount of binder resin adsorbed per surface area of ​​the conductive powder and ceramic powder in the obtained conductive paste composition was 4.9 mg / m2. 2 It was.

[0078] Example 3 A conductive paste composition was prepared in the same manner as in Example 1, except that 0.1 g of oleoyl sarcosine (average molecular weight: 353.55) was prepared as an anionic dispersant and added together with the nickel powder and the ceramic powder, and the paste viscosity was measured and the sheet attack was evaluated. The ratio of oleoyl sarcosine to 100 parts by mass of nickel powder was 0.1 part by mass, and the content of oleoyl sarcosine in the conductive paste composition was 0.05% by mass.

[0079] Conductive paste composition shear rate at 25°C: 100 sec -1 The viscosity is 1.0 Pa·s, the shear rate is 10,000 sec at 25°C. -1 The viscosity at 0.2 Pa·s and the shear rate at 25°C are 0.025 sec -1 The viscosity at 1000 g / cm2 was 50 Pa s. The amount of binder resin adsorbed per surface area of ​​the conductive powder and ceramic powder in the obtained conductive paste composition was 2.7 mg / m2. 2 It was.

Claims

1. The conductive powder, the ceramic powder, the binder resin, and the organic solvent are included. The binder resin has an adsorption amount per surface area of ​​the conductive powder and / or the ceramic powder of 0.2 mg / m ２ 15mg / m or more ２ Adsorption occurs within the range below. Conductive paste composition.

2. The composition includes a conductive powder, a ceramic powder, a dispersant, a binder resin, and an organic solvent. The binder resin has an adsorption amount per surface area of ​​the conductive powder and / or the ceramic powder of 0.2 mg / m ２ 15mg / m or more ２ Adsorption occurs within the range below. Conductive paste composition.

3. The amount of adsorption per surface area of ​​the conductive powder and / or the ceramic powder is 1.0 mg / m ２ 10mg / m or more ２ The conductive paste composition according to claim 1 or 2, wherein the range is as follows:

4. The amount of adsorption per surface area of ​​the conductive powder and / or the ceramic powder is 2.0 mg / m ２ 5.0mg / m or more ２ The conductive paste composition according to claim 1 or 2, wherein the range is as follows:

5. the organic solvent is a mixed solvent containing a first solvent made of a terpene solvent, a second solvent made of a petroleum-based hydrocarbon, and a third solvent different from the first solvent and the second solvent; The third solvent is at least one selected from β-ketoester solvents, 2-ethylhexyl acetate, furfuryl acetate, 1,6-hexanediol acetate, diethylene glycol butyl ether acetate (BCA), linalyl acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether, diethylene glycol monomethyl ether, and propylene glycol butyl ether (PNB); The conductive paste composition according to claim 1 or 2.

6. 6. The conductive paste composition according to claim 5, wherein the mixed solvent contains 40% by mass or more and 60% by mass or less of the first solvent, 10% by mass or more and 40% by mass or less of the second solvent, and more than 0% by mass or less and 50% by mass or less of the third solvent.

7. 3. The conductive paste composition according to claim 1, wherein the conductive powder is at least one selected from the group consisting of nickel, copper, gold, silver, platinum, palladium, and alloys thereof.

8. 3. The conductive paste composition according to claim 1, wherein the conductive powder has an average particle size of 0.05 μm or more and 0.5 μm or less.

9. 3. The conductive paste composition according to claim 1, wherein the content of the conductive powder is 30% by mass or more and 70% by mass or less based on the total amount of the conductive paste composition.

10. 3. The conductive paste composition according to claim 1, wherein the content of the binder resin is from 1% by mass to 5% by mass with respect to the total amount of the conductive paste composition.

11. 3. The conductive paste composition according to claim 1, wherein the ceramic powder is barium titanate.

12. 3. The conductive paste composition according to claim 1, wherein the ceramic powder has an average particle size of 0.01 μm or more and 0.2 μm or less.

13. 3. The conductive paste composition according to claim 1, wherein the content of the ceramic powder is 3 parts by mass or more and 25 parts by mass or less with respect to 100 parts by mass of the conductive powder.

14. The conductive paste composition according to claim 2 , wherein the content of the dispersant is from 0.01 parts by mass to 2.0 parts by mass with respect to 100 parts by mass of the conductive powder.