Support, conductive paste, electronic component, and laminated ceramic capacitor

Abstract

Provided are a carrier, a conductive paste, an electronic component, and a multilayer ceramic capacitor, which are capable of maintaining the smoothness and the density of a dried film of the conductive paste in a good state while suppressing sheet erosion of a green sheet, in a conductive paste using a fine conductive powder and a ceramic powder for miniaturization and thinning of a multilayer ceramic electronic component. A carrier is a carrier containing a binder resin and an organic solvent, wherein the binder resin contains a high molecular compound in which a cellulose-based compound and a polyvinyl acetal-based compound are bonded via a sulfur atom, the molar ratio of the sulfur atom contained in the high molecular compound to the cellulose-based compound is 0.3 to 1.7, and the hydrogen bond term δh of the Hansen solubility parameter of the organic solvent is 6.5 MPa0.5 or less.

Description

Technical Field

[0001] This invention relates to carriers, conductive pastes, electronic components, and multilayer ceramic capacitors. Background Technology

[0002] With the miniaturization and increasing performance of electronic devices such as mobile phones and digital devices, there is also a desire for miniaturization and high capacitance in electronic components, including multilayer ceramic capacitors. Multilayer ceramic capacitors have a structure consisting of multiple dielectric layers and multiple internal electrode layers stacked alternately. By thinning these dielectric layers and internal electrode layers, miniaturization and high capacitance can be achieved.

[0003] Multilayer ceramic capacitors are manufactured as follows: First, a conductive paste for internal electrodes is printed (coated) in a predetermined electrode pattern on the surface of a green wafer containing dielectric powder such as barium titanate (BaTiO3) and binder resin such as polyvinyl acetal resin (PVA), and then dried to form a dry film. Next, the dry film and the green wafer are stacked alternately and heated and pressed to form a laminate in which the dry film and the green wafer are integrated. The laminate is cut, and after being subjected to a binder removal treatment in an oxidizing atmosphere or an inert atmosphere, it is fired to obtain a fired chip. Then, a paste for external electrodes is coated on both ends of the fired chip, and after firing to form external electrodes, the surface of the external electrodes is plated with nickel or the like to obtain a multilayer ceramic capacitor (MLCC). In addition, the conductive paste for internal electrodes contains conductive powder such as nickel powder, ceramic powder such as barium titanate powder, organic binder, and solvent.

[0004] In recent years, MLCCs have pursued further miniaturization and increased capacity. For example, for internal electrodes using materials such as nickel, research is underway to achieve dense and highly continuous electrode films. For ceramic dielectric materials and dielectric layers using ceramic dielectric materials, research is being conducted to achieve high dielectric constants and thinner layers. Materials with dielectric layer thicknesses of 1.0 μm or less have already been put into practical use. Furthermore, for electrode films, a thickness of 1.0 μm or less is also desired.

[0005] If MLCCs are made thinner, the adhesion between the green wafer and the internal electrode layer decreases, leading to problems such as warping and frequent misalignment due to poor bonding during lamination. This poor bonding, for example, causes short-circuit faults in multilayer ceramic capacitors. In particular, due to the requirement for multilayer MLCCs, the thickness of each dielectric layer is reduced by using fine-particle dielectric powder, and the number of layers is increased; therefore, improvement of this poor bonding is desirable. If the adhesion between the wafers is weak, structural defects such as voids, delamination, and cracks will occur due to firing, reducing the yield of MLCCs. Therefore, improving the adhesion between the internal electrode layer and the green wafer aims to prevent cracking.

[0006] Using polyvinyl acetal resin as an organic binder in conductive slurries can prevent electrode peeling during the cutting of the laminate. Furthermore, cellulose resin is preferably added to the conductive slurry to impart the desired rheological properties.

[0007] Therefore, Patent Document 1 discloses that: preferably, the slurry for the internal electrode can contain an organic resin, which is a mixture of ethyl cellulose (EC) and polyvinyl butyral (PVB) resin, which is a type of polyvinyl acetal (PVA) resin.

[0008] However, if the conductive paste used for the internal electrodes contains PVA, then a solvent for dissolving PVA is used as the solvent for the conductive paste. Thus, depending on the solvent used to dissolve the PVA contained in the conductive paste, the PVA contained in the green sheet will dissolve and erode, resulting in a risk of sheet erosion. If sheet erosion occurs, the thickness of the green sheet will locally thin or open, leading to poor formation of the internal electrodes or the disappearance of the green sheet between the internal electrodes, causing the internal electrodes to connect and thus becoming a cause of short circuits. Therefore, Patent Document 2 discloses a special solvent composition capable of addressing sheet erosion.

[0009] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2009-147359; Patent Document 2: Japanese Patent Application Publication No. 2020-057691. Summary of the Invention

[0010] The problem that the invention aims to solve Generally, when two organic binder resins with significantly different structures are mixed, they become almost incompatible (non-compatible) combinations. In the case of an incompatible system, since the two organic binder resins are essentially immiscible and exist independently, not only are the performances expected by using both organic binder resins not achieved, but the functionality is often significantly reduced compared to using the organic binders individually. Moreover, because the solvents contained are suitable for both organic binder resins, the solvents that dissolve the PVA increase the risk of the aforementioned sheet corrosion.

[0011] If organic adhesive resins that would not normally mix can be made compatible with each other, it is possible to achieve a uniform and stable dispersion state that combines the advantages of both, stabilizing the interfaces between different polymers.

[0012] In the conductive slurry disclosed in Patent Document 1, the inclusion of polyvinyl butyral resin improves the adhesion between the dried film and the raw sheet. However, in this technology, because ethyl cellulose resin and polyvinyl butyral resin are used together, sometimes the poor compatibility of the two resins leads to insufficient dispersion of the conductive powder and ceramic powder in the conductive slurry, or insufficient density and smoothness of the dried film of the conductive slurry.

[0013] Furthermore, when the conductive paste contains both polyvinyl acetal resin and cellulose-based resin, it becomes important to select a solvent capable of dissolving both resins, or a solvent composed of a mixture of multiple types of solvents, as the solvent used for the conductive paste. On the other hand, it is necessary to select a solvent capable of inhibiting sheet corrosion. In particular, if a solvent capable of dissolving polyvinyl acetal resin is selected as the solvent for the conductive paste, there is a risk of sheet corrosion if the solvent's solubility in the polyvinyl acetal resin contained in the raw sheet is not taken into account.

[0014] In view of this situation, the object of the present invention is to provide a carrier, a conductive paste, an electronic component, and a multilayer ceramic capacitor that, in a conductive paste using finely ground conductive powder or ceramic powder for miniaturization and thinning of multilayer ceramic electronic components, can maintain the smoothness and density of the dried film of the conductive paste in a good state, while suppressing sheet erosion of the green sheet.

[0015] means for solving problems To address the aforementioned problems, the carrier of the present invention comprises an adhesive resin and an organic solvent. The adhesive resin comprises a polymeric compound formed by the bonding of cellulose-based compounds and polyvinyl acetal-based compounds through sulfur atoms. The molar ratio of sulfur atoms in the polymeric compound to those in the cellulose-based compound is 0.3 to 1.7. The hydrogen bonding term δh of the Hansen solubility parameter of the organic solvent is 6.5 MPa. 0.5 the following.

[0016] The hydrogen bonding term δh of the Hansen solubility parameter of the polymer compound can also be 6.5~8.5 MPa. 0.5 .

[0017] Alternatively, the cellulose compound may be a cellulose derivative having a thiol group or a vinyl group, and the polyvinyl acetal compound may be a polyvinyl acetal resin having a thiol group or a vinyl group. If the cellulose derivative has a thiol group, the polyvinyl acetal resin has a vinyl group that reacts with the thiol group. If the cellulose derivative has a vinyl group, the polyvinyl acetal resin has a thiol group that reacts with the vinyl group.

[0018] Alternatively, the cellulose derivative may be ethyl cellulose containing thiol groups or vinyl groups, and the polyvinyl acetal resin may be polyvinyl butyral containing thiol groups or vinyl groups.

[0019] Alternatively, the cellulose-based compound may be a first esterification product formed by the dehydration condensation of the carboxyl group of a carboxylic acid containing a thiol group or a vinyl group and the hydroxyl group of cellulose, and the polyvinyl acetal-based compound may be a second esterification product formed by the dehydration condensation of the carboxyl group of a carboxylic acid containing a thiol group or a vinyl group and the hydroxyl group of polyvinyl acetal. If the first esterification product contains a thiol group, the second esterification product contains a vinyl group; if the first esterification product contains a vinyl group, the second esterification product contains a thiol group. The polymer compound may be a thiol-ene reaction product of the first esterification product and the second esterification product.

[0020] Alternatively, the first esterification product can be an esterification product formed by the dehydration condensation of the carboxyl group of 3-allyloxypropionic acid and the hydroxyl group of ethyl cellulose, and the second esterification product can be an esterification product formed by the dehydration condensation of the carboxyl group of 3-mercaptopropionic acid and the hydroxyl group of polyvinyl butyral.

[0021] Furthermore, to address the aforementioned problems, the conductive slurry of the present invention comprises the carrier, conductive powder, and ceramic powder of the present invention, wherein the hydrogen bonding term δh of the Hansen solubility parameter of the organic solvent in the conductive slurry is 6.5 MPa. 0.5 the following.

[0022] The number-average particle size of the conductive powder can also be greater than 0.05 μm and less than 1.0 μm.

[0023] The ceramic powder may also contain barium titanate.

[0024] The number-average particle size of the ceramic powder can also be above 0.01 μm and below 0.5 μm.

[0025] The content of the ceramic powder can also be more than 1% by mass and less than 20% by mass.

[0026] The conductive paste of the present invention can also be used for the internal electrodes of laminated ceramic components.

[0027] In addition, in order to solve the above problems, the electronic component of the present invention is an electronic component formed using the conductive paste of the present invention.

[0028] In addition, to solve the above problems, the multilayer ceramic capacitor of the present invention has at least a multilayer body formed by stacking a dielectric layer and an internal electrode layer, wherein the internal electrode layer is formed using the conductive paste of the present invention.

[0029] Invention Effects The carrier of the present invention, through the selection of the adhesive resin, possesses the characteristics of polyvinyl acetal resin, and through the selection of the solvent, it is able to suppress sheet erosion of the conductive paste. Furthermore, the conductive paste using the carrier of the present invention exhibits excellent dispersibility of the conductive powder and high surface smoothness in the dried film after coating. In addition, the electrode patterns of electronic components such as multilayer ceramic capacitors formed using the conductive paste of the present invention have low surface roughness and high dried film density. Attached Figure Description

[0030] Figure 1A This is a perspective view showing the multilayer ceramic capacitor involved in this embodiment.

[0031] Figure 1B This is a cross-sectional view showing the multilayer ceramic capacitor according to this embodiment. Detailed Implementation

[0032] The following describes one embodiment of the carrier, conductive paste, electronic components, and multilayer ceramic capacitor of the present invention.

[0033] [Carrier] The carrier of the present invention comprises the adhesive resin and organic solvent described below.

[0034] <Adhesive Resin> The adhesive resin contained in the carrier is a polymeric compound composed of cellulose-based compounds and polyvinyl acetal-based compounds bonded together by sulfur atoms. The molar ratio of sulfur atoms in the polymeric compound to that in the cellulose-based compound is 0.3 to 1.7, that is, in the polymeric compound, the ratio of cellulose-based compound to sulfur atoms is 1.0:0.3 to 1.7.

[0035] The weight-average molecular weight (Mw) of the polymer compound, converted to standard polystyrene based on gel permeation chromatography (GPC), is preferably between 20,000 and 200,000. When the weight-average molecular weight of the polymer compound is less than 20,000, the viscosity of the conductive paste made from it becomes extremely low, making it difficult to adjust to a suitable viscosity for conductive paste. Conversely, if the weight-average molecular weight of the polymer compound exceeds 200,000, the viscosity of the conductive paste made from it becomes extremely high, making it difficult to adjust to a suitable viscosity for conductive paste, and potentially requiring a lower than appropriate amount of conductive powder or ceramic powder to achieve a suitable viscosity.

[0036] Since the polymer compound of this embodiment has a portion based on a cellulose-based compound and a portion based on a polyvinyl acetal-based compound in its molecule, the dried film obtained from the conductive slurry of this embodiment can possess surface smoothness due to the cellulose-based compound and adhesiveness of a sheet due to the polyvinyl acetal-based compound. Furthermore, by enabling the polymer compound to have a structure incompatible with both cellulose-based and polyvinyl acetal-based compounds within the same molecule, poor dispersion of the conductive slurry can also be eliminated.

[0037] Here, as long as the molar ratio of sulfur atoms in the polymer compound to the cellulose-based compound is 0.5 to 2, the surface roughness of the dried film is superior compared to conventional conductive slurries that use cellulose and polyvinyl acetal resin as adhesive resins. Furthermore, if this molar ratio is 0.3 to 1.7, the surface roughness and dried film density of the conductive slurry's dried film are even more superior. The molar ratio of sulfur atoms in the polymer compound to the cellulose-based compound is 0.3 to 1.7, more preferably 0.5 to 1.5.

[0038] (Hydrogen bonding term δh of Hansen solubility parameter for polymers) The Hansen solubility parameter (HSP) is known as a measure of the solubility of resins in solvents. The HSP is based on the idea that two substances with similar intermolecular interactions readily dissolve in each other. This idea also applies to resins and solvents. The HSP has three terms: dispersion (δd), polarity (δp), and hydrogen bonding (δh). Furthermore, in the carrier and conductive slurry of this embodiment, the hydrogen bonding term (δh) affects the solubility of cellulose, polyvinyl acetal resin, and the aforementioned polymers and organic solvents.

[0039] The values ​​of the Hansen solubility parameter sometimes vary depending on the source, but in this embodiment, for solvents registered in the database of Hansen Solubility Parameter in Practice (HSPiP) version 5, the registered values ​​are used. For solvents not registered, estimated values ​​calculated according to HSP version 5 are used. For the HSP value of the resin, for resins registered in the database, the registered values ​​are used. Additionally, for resins not registered in the database, tests were conducted to dissolve the resin using 20 solvents with defined HSP values, and Hansen balls were calculated based on the HSP values ​​of the solvents that could be dissolved and retrieved using HSP version 5.

[0040] The HSP δh of ethyl cellulose in cellulose-based resins is 5.5~6.5 MPa. 0.5The HSP δh of polyvinyl butyral resin is 10~11 MPa. 0.5 Furthermore, even if the polymer compounds contained in the carrier and conductive slurry of this embodiment have structures derived from polyvinyl acetal resin in their molecules, their HSP δh is still 6.5~8.5 MPa. 0.5 It is close to the value of ethyl cellulose.

[0041] Here, the HSP values ​​for each resin and the polymer compound are values ​​corresponding to the center of the Hansen sphere. This means that the polymer compound of this embodiment can be used in solvents suitable for dissolving ethyl cellulose. Therefore, the amount of solvent that easily causes sheet erosion can be suppressed, which is suitable for dissolving the polyvinyl acetal resin contained in the raw sheet. Based on the solubility of the polymer compound of this embodiment relative to the solvent, sheet erosion can be suppressed. The polymer compound of this embodiment, by having a cellulose structure within its molecule, dissolves in solvents suitable for cellulose.

[0042] (Polymer compounds) The polymeric compounds formed by the bonding of cellulose-based compounds and polyvinyl acetal-based compounds, which can be used in this embodiment, will be described in more detail.

[0043] Both cellulose and polyvinyl acetal possess hydroxyl groups within their molecules. The following cellulose-based compounds were prepared: hydroxyl groups of cellulose were chemically modified by introducing functional groups capable of reacting with other compounds and forming bonds. Conversely, the following polyvinyl acetal-based compounds were prepared: hydroxyl groups of polyvinyl acetal-based polymers were chemically modified by introducing functional groups different from those introduced into the cellulose-based compounds, capable of reacting with other compounds and forming bonds. That is, the reactive functional groups introduced into the cellulose-based compounds and the reactive functional groups introduced into the polyvinyl acetal-based compounds are different. Furthermore, while the functional groups introduced into the cellulose-based compounds and the polyvinyl acetal-based compounds react, it is difficult for them to react with the same functional groups. This difficulty in reacting with the same functional groups is to avoid bonding between the cellulose-based compounds and the polyvinyl acetal-based compounds.

[0044] Then, if the functional groups introduced into the cellulose-based compound and the functional groups introduced into the polyvinyl acetal-based compound bond together, a polymeric compound formed by the bonding of the cellulose-based compound and the polyvinyl acetal-based compound will be obtained. Specifically, if a thiol group is introduced into cellulose to form a cellulose-based compound, and a vinyl group is introduced into the polyvinyl acetal resin to form a polyvinyl acetal-based compound, the double bond of the vinyl group and the sulfur atom of the thiol group bond in the presence of a nucleophile or under conditions that generate free radicals. As a polymeric compound used as an adhesive resin in the conductive slurry of this embodiment, a polymeric compound formed by the bonding reaction of the thiol group and the vinyl group can be obtained. Of course, it is also possible to introduce a vinyl group into the hydroxyl group of cellulose to form a cellulose-based compound, and to introduce a thiol group into the hydroxyl group of the polyvinyl acetal resin to form a polyvinyl acetal-based compound.

[0045] That is, the cellulose-based compound can be a cellulose derivative having a thiol group or a vinyl group, and the polyvinyl acetal-based compound can be a polyvinyl acetal resin having a thiol group or a vinyl group. Moreover, when the cellulose derivative has a thiol group, the polyvinyl acetal resin has a vinyl group that reacts with the thiol group; when the cellulose derivative has a vinyl group, the polyvinyl acetal resin has a thiol group that reacts with the vinyl group.

[0046] The cellulose-based polymer used as the binder resin in the conductive slurry of this embodiment is preferably a polymer that has undergone chemical modification of the hydroxyl groups and compound bonds present in cellulose, a natural polymer. Furthermore, this chemical modification differs from chemical modification involving the introduction of the aforementioned reactive functional groups; it is a chemical modification performed for alkyl etherification, esterification, etc.

[0047] For the bonding of compounds with the hydroxyl groups of cellulose, examples include alkyl etherification and esterification. Examples of celluloses containing hydroxyl groups include methylcellulose, ethylcellulose, propylcellulose, butylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxybutylmethylcellulose, cellulose acetate (acetylcellulose, diacetylcellulose, triacetylcellulose, etc.), cellulose acetate propionate, cellulose acetate butyrate, and nitrocellulose. A single type of cellulose can be used, or two or more can be used in combination.

[0048] Since the conductive slurry of the embodiment contains an organic solvent, it is preferable that the cellulose is also dissolved in the organic solvent. From the perspective of solubility in organic solvents and smoothness of the dried film of the conductive slurry, ethyl cellulose is more preferably used as the cellulose.

[0049] The molecular weight of cellulose affects the viscosity of the conductive slurry of this embodiment. The number-average molecular weight (Mn) of cellulose, converted to standard polystyrene based on GPC, is preferably 10,000 to 100,000, more preferably 10,000 to 80,000.

[0050] When the number-average molecular weight of cellulose is less than 10,000, the viscosity of conductive pastes made from it may sometimes be lower than the appropriate viscosity. In addition, if the number-average molecular weight of cellulose exceeds 100,000, the viscosity of conductive pastes made from it may sometimes be too high.

[0051] Not all hydroxyl groups in cellulose are chemically modified. In the case of cellulose before chemical modification, each ring structure constituting cellulose has three hydroxyl groups. In the case of chemically modified cellulose, if averaged over each ring structure constituting the glucose ring, 0.1 to 1 hydroxyl groups remain in a hydroxyl state and are not chemically modified. In this invention, reactive functional groups are introduced into these unmodified hydroxyl groups.

[0052] On the other hand, polyvinyl acetal is typically a polymer composed of monomer units of vinyl acetal / vinyl alcohol / vinyl acetate, which can be obtained by saponifying polyvinyl acetate to obtain polyvinyl alcohol, and then further acetalizing the polyvinyl alcohol. Specifically, examples of polyvinyl acetal include polyvinyl butyralized polyvinyl alcohol (polyvinyl butyral) and polyvinyl formalized polyvinyl alcohol (polyvinyl formal).

[0053] Polyvinyl acetal is a commercially available product, sold by companies such as Sekisui Chemicals and KURARAY, with varying degrees of butyralization, formaldehydeization, acetyl groups, hydroxyl groups, and molecular weights. Polyvinyl acetal can be used alone or in combination with two or more types.

[0054] Polyvinyl acetal is preferably soluble in organic solvents. From the perspective of high solubility relative to organic solvents, polyvinyl acetal is more preferably polyvinyl butyral.

[0055] Polyvinyl acetal, used as a polymer compound, affects film strength and solution viscosity through its molecular weight. Therefore, the number-average molecular weight of polyvinyl acetal, converted from standard polystyrene based on GPC, is preferably in the range of 5,000 to 150,000, and more preferably in the range of 10,000 to 100,000.

[0056] When the number average molecular weight of polyvinyl acetal is less than 5,000, the viscosity of conductive pastes made from it may sometimes be lower than the appropriate viscosity. In addition, if the number average molecular weight of polyvinyl acetal exceeds 150,000, the viscosity of conductive pastes made from it may sometimes be too high.

[0057] Polyvinyl acetal has at least one hydroxyl group in one molecule. Generally, polyvinyl acetal has 20-40 mol% hydroxyl groups as vinyl alcohol units constituting the polymer. Chemical modification is achieved by introducing reactive functional groups into these hydroxyl groups.

[0058] As a compound chemically modified by reacting with the hydroxyl groups of cellulose or polyvinyl acetal, a compound having a thiol or vinyl group at one end and a carboxyl group at the other end can be used. The carboxyl group of this compound undergoes dehydration condensation with the hydroxyl groups of cellulose-based polymers or polyvinyl acetals to form an ester bond.

[0059] (Methods for synthesizing polymers) Hereinafter, an example of a method for synthesizing the polymeric compound used in this embodiment will be described. To obtain cellulose-based compounds and polyvinyl acetal-based compounds, esterification or etherification of compounds having functional groups that react with hydroxyl groups and functional groups that are reactive with other compounds, or with the hydroxyl groups of cellulose or polyvinyl acetal, is performed. Examples of functional groups that react with hydroxyl groups include carboxyl groups and hydroxyl groups.

[0060] Esterification reactions can be carried out using condensing agents, for example. Examples of condensing agents include carbodiimide, diphenyl azidophosphate, and 1-hydroxybenzotriazole. Only one condensing agent can be used, or two or more can be used in combination. Among these, carbodiimide is preferred due to its versatility, excellent reactivity, and ability to react at low temperatures without being affected by moisture in the reaction environment.

[0061] Examples of carbodiimides include dicyclohexylcarbodiimide, diisopropylcarbodiimide, N-[3-(dimethylamino)propyl]-N'-ethylcarbodiimide, and N-[3-(dimethylamino)propyl]-N'-ethylcarbodiimide methyl iodide. From the viewpoint of availability, dicyclohexylcarbodiimide and diisopropylcarbodiimide are preferred. Furthermore, when using carbodiimides, it is preferable to use dimethylaminopyridine or triethylamine as a reaction promoter in the range of 0.01 mol% to 10 mol% relative to the carbodiimide.

[0062] On the other hand, etherification reactions can be carried out efficiently by using alkali metal hydroxides such as KOH and NaOH, and hydrides of alkali metals such as NaH and KH as reaction catalysts.

[0063] To obtain cellulose-based compounds, it is also preferable to dissolve cellulose in an aprotic solvent such as ethyl acetate, mix a compound having a carboxyl group that forms an ester bond with a hydroxyl group and a vinyl or thiol group that serves as a functional group to react with other compounds, and use a condensing agent and a base such as dimethylaminopyridine, which is used as a nucleophile to promote the esterification reaction in the range of 0.01 mol% to 10 mol%.

[0064] In the polymer used in this embodiment, the molar ratio of sulfur atoms to cellulose-based compounds is 0.3 to 1.7 (cellulose-based compounds: sulfur atoms = 1.0: 0.3 to 1.7). Therefore, for every 1 mol of cellulose, 0.3 to 1.7 mol of a compound with functional groups that react with other compounds needs to be added.

[0065] The preferred reaction temperature for synthesizing cellulose-based compounds is between room temperature and 50°C. In the system where the synthesis reaction of the cellulose-based compounds has been completed, a mixture exists containing unreacted cellulose without a functional group that is reactive with other compounds, a cellulose-based compound with one functional group that is reactive with other compounds, and a cellulose-based compound with multiple functional groups that are reactive with other compounds. Chemical modification is a matter of probability, but the cellulose-based compounds with one hydroxyl group of cellulose chemically modified are the most common. Furthermore, in this invention, a mixture of these unreacted celluloses, celluloses with multiple of the aforementioned functional groups, and celluloses with one of the aforementioned functional groups is used as the cellulose-based compound. Moreover, once the synthesis of the cellulose-based compound is complete, the solvent can be removed by distillation.

[0066] To synthesize polyvinyl acetal compounds, it is preferable to dissolve polyvinyl acetal in an aprotic solvent such as ethyl acetate, mix a compound having a carboxyl group that forms an ester bond with a hydroxyl group and a vinyl or thiol group as a functional group to react with other compounds, and use a condensing agent and a base such as dimethylaminopyridine, which is a nucleophile in the range of 0.01 mol% to 10 mol% to promote the esterification reaction.

[0067] The reaction temperature for chemically modifying the hydroxyl groups of polyvinyl acetal is preferably in the range of room temperature to 50°C. Furthermore, thiol or vinyl functional groups are introduced into the polyvinyl acetal, but not into all of the polyvinyl acetal; rather, unreacted polyvinyl acetal is present in the mixture. In this invention, the mixture of these unreacted polyvinyl acetals and the functionalized polyvinyl acetals is used as a polyvinyl acetal-based compound. Moreover, once the synthesis of the polyvinyl acetal-based compound is complete, the solvent can be removed by distillation.

[0068] The polymeric compounds used in this embodiment are synthesized by the following steps: dissolving a cellulose-based compound and a polyvinyl acetal-based compound in a solvent, adding a free radical initiator and heating, reacting the vinyl group of one of the cellulose-based compound and the thiol group of the other, and bonding the cellulose-based compound and the polyvinyl acetal-based compound.

[0069] Alternatively, cellulose compounds and polyvinyl acetal compounds can be dissolved in a solvent, and nucleophiles, primarily amines or other bases, can be added and then heated.

[0070] The reaction temperature for bonding cellulose compounds and polyvinyl acetal compounds can be appropriately selected, preferably above 60°C.

[0071] For example, the cellulose derivative could be ethyl cellulose containing thiol groups or vinyl groups, and the polyvinyl acetal resin could be polyvinyl butyral containing thiol groups or vinyl groups.

[0072] Specifically, the cellulose-based compound can also be a first esterification product formed by the dehydration condensation of the carboxyl group of a carboxylic acid containing a thiol group or a vinyl group and the hydroxyl group of cellulose. Similarly, the polyvinyl acetal-based compound can be a second esterification product formed by the dehydration condensation of the carboxyl group of a carboxylic acid containing a thiol group or a vinyl group and the hydroxyl group of a polyvinyl acetal. Furthermore, if the first esterification product contains a thiol group, the second esterification product contains a vinyl group; if the first esterification product contains a vinyl group, the second esterification product contains a thiol group. The polymer compound can also be a thiol-ene reaction product of the first and second esterification products.

[0073] More specifically, the first esterification product can also be an esterification product formed by the dehydration condensation of the carboxyl group of 3-allyloxypropionic acid and the hydroxyl group of ethyl cellulose, and the second esterification product can also be an esterification product formed by the dehydration condensation of the carboxyl group of 3-mercaptopropionic acid and the hydroxyl group of polyvinyl butyral.

[0074] The reaction that bonds the cellulose-based compound and the polyvinyl acetal-based compound is preferably carried out in the solvent of the support of this embodiment, as described later. When the reaction that bonds the cellulose-based compound and the polyvinyl acetal-based compound is carried out in the solvent of the support, the polymer of this embodiment is obtained in a state where it is dissolved in the solvent of the support. That is, by carrying out the reaction that bonds the cellulose-based compound and the polyvinyl acetal-based compound, a support formed by dissolving the polymer in the solvent can be obtained.

[0075] Furthermore, in the carrier of this embodiment, in addition to the polymer compound, it may contain cellulose resin and polyvinyl acetal resin, or either cellulose resin or polyvinyl acetal resin, or both of these may be contained independently of the polymer compound.

[0076] Generally, cellulose resins and polyvinyl acetal resins are incompatible as described above. However, the polymeric compound facilitates the compatibility of cellulose resins and polyvinyl acetal resins, suppressing phase separation. Furthermore, because the polymeric compound promotes the compatibility of cellulose resins and polyvinyl acetal resins, even when using solvents that more readily dissolve cellulose resins than polyvinyl acetal resins as carriers or conductive slurries, the coexistence of the polymeric compound with the polyvinyl acetal resin demonstrates the ability to dissolve the polyvinyl acetal resin. These effects arise from the presence of both a cellulose-based backbone and a polyacetal-based backbone within the molecule of the polymeric compound.

[0077] In the carrier of this embodiment, the proportion of the polymer compound in the adhesive resin to the total mass of the cellulose resin, polyvinyl acetal resin, and the polymer compound is 20% by mass or more, preferably 30% by mass or more. When the proportion of the polymer compound to the total mass of the cellulose resin, polyvinyl acetal resin, and the polymer compound is less than 20% by mass, there is a situation where the suppression of phase separation is limited to a portion of the conductive slurry, which is not a satisfactory result. Furthermore, the proportion of the polymer compound in the adhesive resin to the total mass of the cellulose resin, polyvinyl acetal resin, and the polymer compound can be set to 99% by mass or less or 95% by mass or less.

[0078] If such phase separation occurs, the dried film obtained by printing (coating) and drying the conductive paste will have inhomogeneities in the binder resin, conductive powder, and ceramic powder. In the internal electrode obtained by firing this dried film, voids without conductive material may sometimes appear due to the inhomogeneity of the binder resin and ceramic powder. If such voids occur in the internal electrode, the capacity of the MLCC will decrease because the area of ​​the internal electrode becomes narrower. The effect of polymer compounds in suppressing phase separation of cellulose resin and polyvinyl acetal resin helps to homogenize the particle distribution in the dried film. As a result, the film rupture phenomenon of the electrode layer after firing is resolved, and the capacity of the MLCC increases.

[0079] In the carrier of this embodiment, since it can contain one or more resins selected from cellulose resin and polyvinyl acetal resin, the degree of freedom in adjusting the viscosity of the conductive paste is also increased. That is, since cellulose resin and polyvinyl acetal resin can be appropriately added within the scope of this embodiment, the viscosity adjustment of the conductive paste becomes easier.

[0080] As usable cellulose resins, methylcellulose resin, ethylcellulose resin, ethyl hydroxyethylcellulose resin, nitrocellulose resin, and other cellulose resins can be selected, with ethylcellulose resin being preferred. Furthermore, these cellulose resins can be used alone or in combination of two or more. As usable polyvinyl acetal resins, polyvinyl butyral can be selected. Either the cellulose resin or the polyvinyl acetal resin can be used alone or both. Furthermore, the mixing ratio of the cellulose resin, the polyvinyl acetal resin, and the polymer compound can be appropriately selected as long as it does not deviate from the scope of this embodiment. By selecting these resins and their mixing ratios, the viscosity of the conductive slurry and the adhesion of the resulting dried film to the substrate can be appropriately adjusted.

[0081] In this embodiment, in addition to cellulose resin and polyvinyl acetal resin, known adhesive resins such as acrylic resin and maleate resin can also be added. The number-average molecular weight of the resins that can be added in this way, excluding cellulose resin and polyvinyl acetal resin, is approximately 20,000 to 300,000 according to GCP (gel permeation chromatography) analysis.

[0082] <Organic Solvents> The HSP δh of the solvent that can be used as the carrier in this embodiment is 6.5 MPa. 0.5 The following is preferred: 6MPa 0.5 Hereinafter, 5.5 MPa is further preferred. 0.5 Hereinafter, 5MPa is further preferred. 0.5 Below. On the other hand, the lower limit of δh for the HSP of the solvent is 0.5 MPa. 0.5 The above is preferably 1.5 MPa. 0.5 The above, more preferably 2.5 MPa 0.5 The solvent can be a single solvent or a mixture of multiple solvents. The Hansen solubility parameter of the mixed solvent can be calculated by multiplying the volume percentage of the solvents constituting the mixed solvent by the HSP values ​​δd, δp, and δh of that solvent and summing the results. Of course, the solvent used as the carrier in this embodiment only needs to have an HSP value δh of 6.5 MPa. 0.5The following solvents are suitable for dissolving polymeric compounds and cellulose-based resins, but not for dissolving butyral resin contained in raw sheets. The solubility of butyral resin in the carrier used in this embodiment is considered to suppress sheet erosion. This is achieved as long as the lower limit of δh for HSP is 0.5 MPa. 0.5 The above methods can dissolve polymers and cellulose resins.

[0083] As such solvents, solvents that can be used as standalone solvents include acetate esters such as isobornyl acetate, isobornyl propionate, isobornyl butyrate, isobornyl isobutyrate, and diethylene glycol monoethyl ether acetate; ether solvents such as ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and diethylene glycol dibutyl ether; and terpene solvents such as dihydroterpineol acetate and terpineol acetate.

[0084] Additionally, in mixed solvents consisting of multiple solvents, the δh value of HSP can also be 6.5 MPa. 0.5 The following are conditions under which ethylene glycol monobutyl ether acetate, dipropylene glycol methyl ether acetate, diethylene glycol monobutyl ether acetate, terpineol, and dihydroterpineol are added.

[0085] Furthermore, the HSP δh of the solvent contained in the carrier of this embodiment is 6.5 MPa. 0.5 The following is preferred: 6MPa 0.5 Hereinafter, 5.5 MPa is further preferred. 0.5 The following are examples. Further examples include hydrocarbon solvents such as tridecane, nonane, and cyclohexane, and petroleum hydrocarbon solvents such as mineral oil. In addition, one organic solvent may be used, or a mixture of two or more organic solvents may be used.

[0086] (Content of adhesive resin and organic solvent in the carrier) The carrier is one of the raw materials for the conductive paste described later. Alternatively, the carrier can be a mixture of a polymer and an organic solvent, obtained by reacting a cellulose-based compound and a polyvinyl acetal-based compound in an organic solvent. Furthermore, the carrier can also be a material obtained by further adding an organic solvent to the mixture. Additionally, the carrier can be a material obtained by dissolving a solid polymer in an organic solvent.

[0087] Therefore, the content of the binder resin and the content of the organic solvent in the carrier can be appropriately adjusted. For example, the mass ratio of the binder resin and the organic solvent can be adjusted such that the total amount of the binder resin and the organic solvent of the manufactured conductive slurry is included in the carrier, or the mass ratio of the binder resin and the organic solvent can be adjusted such that the total amount of the binder resin and a portion of the organic solvent of the conductive slurry is included in the carrier. For example, the mass ratio of the binder and the organic solvent in the carrier can be 5~50:95~50.

[0088] [Conductive paste] The conductive paste of this embodiment includes a carrier, conductive powder, and ceramic powder. The components will be described in detail below.

[0089] <Conductive Powder> There are no particular limitations on the conductive powder; metallic powders can be used, for example, powders selected from Ni, Pd, Pt, Au, Ag, Cu, and alloys thereof. From the viewpoints of conductivity, corrosion resistance, and cost, Ni powder or its alloys are preferred. As a Ni alloy, for example, an alloy of Ni with at least one element selected from the group consisting of Mn, Cr, Co, Al, Fe, Cu, Zn, Ag, Au, Pt, and Pd (Ni alloy) can be used. The Ni content in the Ni alloy is, for example, 50% by mass or more, preferably 80% by mass or more. Furthermore, during the debinding process, in order to suppress the rapid gas generation caused by the localized thermal decomposition of the adhesive resin, the Ni powder may also contain approximately several hundred ppm of S.

[0090] There are no particular limitations on the manufacturing method of conductive powder. For example, methods such as directly precipitating chloride vapor from the gas phase in hydrogen, atomization from molten metal, spray thermal decomposition using aqueous solution, and wet method of reducing the metal salt of the raw material in aqueous solution can be used.

[0091] There is no particular limitation on the number-average particle size of the conductive powder; it can be selected based on factors such as the size of the electronic component to which it will be used. For example, a particle size of 0.05 μm or more and 1.0 μm or less is acceptable. For instance, as a conductive powder used in multilayer ceramic capacitors for advancing thin-film fabrication, the number-average particle size of the conductive powder is preferably 0.5 μm or less, more preferably 0.3 μm or less. When the number-average particle size exceeds 0.5 μm, the electrical characteristics of the capacitor deteriorate due to increased unevenness on the surface of the internal electrodes, which is therefore undesirable. Furthermore, there is no particular limitation on the lower limit of the number-average particle size of the conductive powder; for example, it is 0.03 μm or more. When the number-average particle size is smaller than 0.03 μm, operation becomes extremely difficult.

[0092] Furthermore, the number-average particle size of the conductive powder is a value obtained based on observations using a scanning electron microscope (SEM), which is the average value obtained by measuring the particle size of each of multiple particles from an image observed by the SEM at 10,000x magnification.

[0093] The content of conductive powder relative to the total amount of conductive slurry is preferably 30% by mass or more and less than 70% by mass, more preferably 40% by mass or more and less than 60% by mass. When the content of conductive powder relative to the total amount of conductive slurry is 30% by mass or more and less than 70% by mass, the conductivity and dispersibility are excellent.

[0094] <Ceramic Powder> There are no particular limitations on the ceramic powder. For example, when using a conductive paste as the internal electrode of a multilayer ceramic capacitor, a known ceramic powder is appropriately selected depending on the type of multilayer ceramic capacitor being used. Examples of ceramic powders include perovskite oxides containing Ba and Ti, with barium titanate (BaTiO3) being the most preferred.

[0095] As ceramic powder, ceramic powder with barium titanate as the main component and oxides as secondary components can also be used. Examples of oxides include oxides of Mn, Cr, Si, Ca, Ba, Mg, V, W, Ta, Nb, and one or more rare earth elements. Alternatively, perovskite-type oxide ceramic powders with strong dielectric properties, for example, in which other atoms, such as Sn, Pb, and Zr, replace the Ba and Ti atoms of barium titanate (BaTiO3), can also be used.

[0096] In the conductive paste used for the internal electrodes, a powder with the same composition as the dielectric ceramic powder constituting the green sheet of the multilayer ceramic capacitor can also be used as the ceramic powder. This suppresses the formation of cracks caused by shrinkage mismatch at the interface between the dielectric layer and the internal electrode layer during the sintering process. Examples of such ceramic powders, besides those mentioned above, include oxides such as ZnO, ferrite, PZT, BaO, Al2O3, Bi2O3, R (rare earth element)2O3, TiO2, and Nd2O3. Furthermore, one or more types of ceramic powder can be used.

[0097] The number-average particle size of the ceramic powder is, for example, 0.01 μm or more and 0.5 μm or less, preferably in the range of 0.01 μm or more and 0.3 μm or less. By making the number-average particle size of the ceramic powder 0.01 μm or more and 0.5 μm or less, when used as a conductive paste for internal electrodes, a sufficiently fine and thin uniform internal electrode can be formed. The number-average particle size is a value obtained based on observation using a scanning electron microscope (SEM), and is the average value obtained by measuring the particle size of each of a plurality of particles in an image observed by SEM at a magnification of 50,000x.

[0098] The content of ceramic powder is preferably 1 part by mass and 30 parts by mass or less relative to 100 parts by mass of conductive powder, more preferably 3 parts by mass and 30 parts by mass or less. When the content of conductive powder is 1 part by mass and 30 parts by mass or less, the conductivity and dispersibility are excellent.

[0099] The content of ceramic powder relative to the total amount of conductive slurry is preferably 1% by mass or more and 20% by mass or less, more preferably 5% by mass or more and 20% by mass or less. When the content of conductive powder is 1% by mass or more and 20% by mass or less, the conductivity and dispersibility are excellent.

[0100] <Carrier> As the carrier has already been specifically described under the item "[Carrier]", detailed descriptions are omitted here. The carrier can be contained in the conductive slurry in a manner in which the content of a polymeric compound formed by the bonding of cellulose-based compounds and polyvinyl acetal-based compounds is preferably 1 part by mass or more and 10 parts by mass or less, more preferably 1 part by mass or more and 8 parts by mass or less, relative to 100 parts by mass of the conductive powder.

[0101] The content of the binder resin relative to the total amount of the conductive slurry is preferably 0.5% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 6% by mass or less. When the content of the binder resin is 0.5% by mass or more and 10% by mass or less, the conductivity and dispersibility are excellent. Therefore, the carrier can be included in the conductive slurry in a manner where the content of the binder resin is 0.5% by mass or more and 10% by mass or less.

[0102] In the conductive slurry of this embodiment, the proportion of the polymer compound in the binder resin to the total mass of the cellulose resin, polyvinyl acetal resin, and the polymer compound is 20% by mass or more, preferably 30% by mass or more. When the proportion of the polymer compound to the total mass of the cellulose resin, polyvinyl acetal resin, and the polymer compound is less than 20% by mass, the suppression of phase separation is limited to a portion of the conductive slurry, which is not a satisfactory result. Furthermore, the proportion of the polymer compound in the binder resin to the total mass of the cellulose resin, polyvinyl acetal resin, and the polymer compound can be set to 99% by mass or less, or 95% by mass.

[0103] <Adhesive Resin> The conductive paste of this embodiment may further include an adhesive resin in addition to the adhesive resin contained in the carrier. Examples of adhesive resins that can be included include the same resins that can be included in the carrier, such as the aforementioned polymeric compounds, cellulose resins, polyvinyl acetal resins, acrylic resins, maleic ester resins, etc. Since details of these adhesive resins have already been described, they will not be omitted here.

[0104] Furthermore, as already explained, the content of the polymer compound relative to 100 parts by mass of the conductive powder is preferably 1 part by mass or more and 10 parts by mass or less, more preferably 1 part by mass or more and 8 parts by mass or less, and the content of the binder resin relative to the total amount of the conductive slurry is preferably 0.5% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 6% by mass or less. Even when the conductive slurry further includes binder resin on the basis of the carrier, the total content of binder resin in the conductive slurry is preferably within these ranges.

[0105] <Organic Solvents> The conductive paste of this embodiment may further contain an organic solvent in addition to the organic solvent contained in the carrier. Examples of organic solvents that can be included include the same solvents that can be included in the carrier. Examples of solvents that can be used as individual solvents include isobornyl acetate, isobornyl propionate, isobornyl butyrate, isobornyl isobutyrate, diethylene glycol monobutyl ether acetate, etc. (acetic acid ester solvents); ether solvents such as diethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, etc. (ether ester solvents); terpene solvents such as dihydroterpineol acetate, terpineol acetate, etc. (terpene acetate ester); hydrocarbon solvents such as tridecane, nonane, cyclohexane, etc.; and petroleum hydrocarbon solvents such as mineral oil. Furthermore, one organic solvent or a mixture of two or more organic solvents may be used.

[0106] Furthermore, the HSP δh of the solvent contained in the conductive paste of this embodiment is 6.5 MPa. 0.5 The following is preferred: 6MPa 0.5 Hereinafter, 5.5 MPa is further preferred. 0.5 Below. Additionally, in a mixed solvent consisting of multiple solvents, the δh value of HSP can also be 6.5 MPa. 0.5 The following are conditions under which ethylene glycol monobutyl ether acetate, dipropylene glycol methyl ether acetate, diethylene glycol monobutyl ether acetate, terpineol, and dihydroterpineol are added.

[0107] The content of the organic solvent relative to 100 parts by weight of the conductive powder is preferably 40 parts by weight or more and 100 parts by weight or less, more preferably 65 parts by weight or more and 95 parts by weight or less. When the content of the organic solvent is 40 parts by weight or more and 100 parts by weight or less, the conductivity and dispersibility are excellent. Furthermore, this range of organic solvent content is the same not only when the organic solvent contained in the carrier is used in the conductive slurry, but also when the organic solvent in addition to the organic solvent contained in the carrier is further contained in the conductive slurry.

[0108] The content of the organic solvent relative to the total amount of the conductive slurry is preferably 20% by mass or more and 60% by mass or less, more preferably 35% by mass or more and 55% by mass or less. When the content of the organic solvent is 20% by mass or more and 60% by mass or less, the conductivity and dispersibility are excellent. Furthermore, this range of organic solvent content is the same not only when the organic solvent contained in the carrier is used in the conductive slurry, but also when the organic solvent in addition to the organic solvent contained in the carrier is further contained in the conductive slurry.

[0109] <Dispersant> The conductive slurry of this embodiment can contain a dispersant. The function of the dispersant is to adsorb onto the surface of the inorganic powder (conductive powder and ceramic powder) to inhibit the aggregation of the inorganic powders or to improve the wettability of the organic carrier relative to the inorganic powder, thereby dispersing the inorganic powder within the conductive slurry. The dispersant (surfactant, etc.) may also contain acidic dispersants including higher fatty acids and polymeric surfactants, cationic dispersants other than acidic dispersants, nonionic dispersants, amphoteric surfactants, and polymeric dispersants.

[0110] In addition, one or more dispersants may be selected. The content of conductive slurry can be appropriately selected by taking into account the viscosity, stickiness, long-term shelf life, etc. of the conductive slurry. Dispersants may be included within a range that does not hinder the effect of the present invention.

[0111] Furthermore, the weight-average molecular weight of the dispersant is preferably 200 to 100,000, more preferably 300 to 30,000. If the weight-average molecular weight is less than 200, the particles cannot obtain sufficient electrostatic repulsion, and the dispersibility and storage stability of the particles may sometimes decrease. Typically, the dispersant adsorbs onto the particle surface to form an adsorption layer, imparting electrostatic and steric repulsion to the particles, resulting in a slurry with excellent dispersibility. However, considering that over time, collisions between particles may exceed the repulsion of the adsorption layer, leading to particle aggregation, the weight-average molecular weight is preferably 200 or higher. Additionally, if the weight-average molecular weight is greater than 100,000, there is a risk of reduced compatibility with organic carriers and organic solvents, particle aggregation, or decreased dispersibility and storage stability. Furthermore, it can also lead to increased viscosity in conductive slurries.

[0112] Regarding the amount of dispersant added, it is preferably 0.01 to 5.00 parts by mass relative to the amount of conductive metal powder added, and more preferably 0.20 to 2.00 parts by mass relative to 100 parts by mass of conductive metal powder content. When the amount of dispersant is less than 0.01 parts by mass, it tends to be difficult to obtain sufficient dispersibility. On the other hand, if it exceeds 5.00 parts by mass, the drying properties deteriorate, and problems such as a decrease in the density of the dried film also occur.

[0113] The polymeric dispersant is preferably anionic, possessing carboxyl or carboxylic anhydride groups. By using anionic polymeric dispersants, the dispersibility of inorganic powders such as conductive powders and ceramic powders onto organic carriers can be further improved. Here, the carboxylic anhydride group refers to the state after the removal of H₂O from two carboxyl groups, resulting in anhydride formation. Examples include phthalic anhydride and maleic anhydride, which are molecular units composed of two carboxyl groups after dehydration.

[0114] Anionic polymeric dispersants preferably possess grafted chains. Grafted chains can also be expected to improve solubility in various organic solvents.

[0115] The weight-average molecular weight of the anionic polymeric dispersant is preferably 1,000 or more and 100,000 or less, more preferably 5,000 or more and 70,000 or less, and even more preferably 10,000 or more and 60,000 or less. By ensuring that the weight-average molecular weight of the polymeric dispersant is 1,000 or more, the dispersibility of inorganic powders to organic carriers can be improved. If the weight-average molecular weight is greater than 100,000, there may be a decrease in compatibility with organic carriers and organic solvents, or agglomeration of particles such as conductive powders and ceramic powders, or a decrease in dispersibility and storage stability.

[0116] Such polymeric dispersants have carboxyl or carboxylic anhydride groups in the functional groups of the main chain. As anionic polymeric dispersants, from the viewpoint of adsorption with inorganic powders, it is preferable to further have oxyethylene groups in the grafted chains.

[0117] Anionic polymeric dispersants can be included in one or more forms. That is, multiple types of polymeric dispersants can be included depending on the length of the main chain, the length of the grafted chain, and the presence or absence of the grafted chain. The content of anionic polymeric dispersants in conductive slurries can be appropriately selected considering the viscosity, tackiness, and long-term shelf life of the conductive slurry, and anionic polymeric dispersants can be included within a range that does not hinder the effects of the present invention.

[0118] Furthermore, the conductive slurry of this embodiment can contain a dispersant other than anionic polymeric dispersants. For example, as a dispersant (surfactant, etc.), it may also contain acidic dispersants including higher fatty acids, phosphoric acid, polymeric surfactants, etc., cationic dispersants other than acidic dispersants, nonionic dispersants, amphoteric surfactants, and polymeric dispersants.

[0119] In addition, the content of dispersant in conductive slurry can be appropriately selected taking into account the viscosity, stickiness, long-term shelf life, etc. of conductive slurry, and dispersant can be included within a range that does not hinder the effect of the present invention.

[0120] Furthermore, for any of the anionic polymeric dispersants and other dispersants, the weight-average molecular weight of the dispersant is preferably 200 to 100,000, more preferably 300 to 30,000. If the weight-average molecular weight is less than 200, the dispersibility and storage stability of the particles may sometimes decrease. Typically, the dispersant adsorbs onto the particle surface to form an adsorption layer, imparting electrostatic and steric repulsion to the particles, thereby obtaining a slurry with excellent dispersibility. However, considering that over time, through collisions between particles, the agglomeration force of the particles exceeds the repulsion of the adsorption layer, causing the particles to aggregate, the weight-average molecular weight is preferably 200 or higher. In addition, if the weight-average molecular weight is greater than 100,000, the compatibility with organic carriers and organic solvents decreases, potentially causing particle aggregation or a decrease in dispersibility and storage stability. Furthermore, it may also lead to an increase in slurry viscosity.

[0121] The total amount of anionic polymeric dispersant and other dispersants added is preferably 0.01 to 5.00 parts by mass relative to the amount of conductive metal powder, and more preferably 0.20 to 2.00 parts by mass relative to 100 parts by mass of conductive metal powder. When the amount of dispersant is less than 0.01 parts by mass, it tends to be difficult to obtain sufficient dispersibility. On the other hand, if it exceeds 5.00 parts by mass, the drying properties deteriorate, and problems such as a decrease in the density of the dried film occur.

[0122] (Other additives) Furthermore, in order to impart flexibility to the dried film obtained from the conductive slurry, known additives such as plasticizers can be added to the conductive slurry.

[0123] (Method for manufacturing conductive paste) There are no particular limitations on the manufacturing method of the conductive slurry of this embodiment, and conventionally known methods can be used. For example, the conductive slurry can be manufactured by preparing the above-mentioned components and then stirring and mixing them using a three-roll mill, ball mill, or mixer. In this case, if a dispersant is pre-coated onto the surface of the conductive powder, the conductive powder will not agglomerate but will be sufficiently loose, and the dispersant will be distributed throughout its surface, easily resulting in a uniform conductive slurry. Alternatively, an organic carrier can be prepared by dissolving the adhesive resin in an organic solvent for the carrier, and then conductive powder, ceramic powder, organic carrier, and dispersant can be added to the organic solvent for the slurry, followed by stirring and mixing using a mixer to produce the conductive slurry.

[0124] Furthermore, regarding the organic solvent used as the carrier, to ensure good compatibility with the organic carrier, it is preferable to use the same organic solvent used for adjusting the viscosity of the conductive slurry. The content of the organic solvent used for the carrier relative to 100 parts by mass of the conductive powder is, for example, 5 parts by mass or more and 80 parts by mass or less. Additionally, the content of the organic solvent used for the carrier relative to the total amount of the conductive slurry is preferably 10% by mass or more and 40% by mass or less.

[0125] The surface smoothness of the dried film formed by printing conductive paste can be evaluated by surface roughness. Furthermore, the surface roughness of the conductive paste can be measured, for example, by the method described in the examples (using a VK-X120 manufactured by Keyence Corporation, based on the ISO 25178 standard to measure the arithmetic mean height Sa). When evaluating the surface smoothness of the dried film by the arithmetic mean height Sa, this value is preferably 0.10 μm or less. If the surface roughness is 0.10 μm or less by the method described in the examples, a low surface roughness can be achieved even after printing onto a green sheet and drying. Considering the manufacturing process of multilayer ceramic capacitors, since the surface roughness of the dried film of the conductive paste is low, the dried film adheres tightly to the green sheet as a surface, resulting in excellent adhesion between the dried film and the green sheet. Therefore, the surface roughness of the dried film of the conductive paste is preferably even lower.

[0126] [Electronic components, multilayer ceramic capacitors] The conductive paste of the present invention is preferably used in electronic components such as multilayer ceramic capacitors. Multilayer ceramic capacitors have a dielectric layer formed using a green sheet and an internal electrode layer formed using a conductive paste.

[0127] For multilayer ceramic capacitors, it is preferable that the dielectric ceramic powder contained in the green sheet and the ceramic powder contained in the conductive paste are powders with the same composition, for example, barium titanate can be used. Multilayer ceramic capacitors manufactured using the conductive paste of this embodiment suppress sheet erosion and poor peeling of the green sheet even when the thickness of the green sheet is, for example, 3 μm or less.

[0128] Hereinafter, embodiments of the electronic components, etc., of the present invention will be described with reference to the accompanying drawings. In the drawings, sometimes the representations are schematic or the scale may be altered. Furthermore, appropriate reference will be made to... Figure 1A , Figure 1B The XYZ orthogonal coordinate system shown illustrates the position and orientation of the component. In this XYZ orthogonal coordinate system, the X and Y directions are horizontal, and the Z direction is vertical (up and down).

[0129] Figure 1A as well as Figure 1B This is a perspective view and a side cross-sectional view of a multilayer ceramic capacitor 1, which is an example of an electronic component according to an embodiment. The multilayer ceramic capacitor 1 includes a ceramic stack 10 formed by alternately stacking a dielectric layer 12 and an internal electrode layer 11, and an external electrode 20.

[0130] The manufacturing method of the multilayer ceramic capacitor 1 using the above-described conductive paste will be described below. First, conductive paste is printed onto a dielectric layer composed of a green sheet and dried to form a dried film. Multiple dielectric layers having the dried film on their upper surfaces are stacked and pressed together to obtain a multilayer body. This multilayer body is then fired to form a single unit, thereby creating a ceramic multilayer body 10 composed of alternating layers of internal electrode layers 11 and dielectric layers 12. Next, a pair of external electrodes 20 are formed at both ends of the ceramic multilayer body 10 to manufacture the multilayer ceramic capacitor 1. The method will be described in more detail below.

[0131] First, a green sheet of unfired ceramic material using a dielectric material is prepared. Examples of such a green sheet include a sheet obtained by adding an organic binder such as polyvinyl butyral and a solvent such as terpineol to a predetermined ceramic raw material powder (e.g., barium titanate) and coating it onto a support film such as a PET film in sheet form, followed by drying to remove the solvent. Furthermore, there is no particular limitation on the thickness of the dielectric layer formed from the green sheet; however, from the viewpoint of miniaturizing multilayer ceramic capacitors, a thickness of 0.05 μm or more and 3 μm or less is preferred.

[0132] Next, multiple sheets of the material are prepared by printing (coating) the aforementioned conductive paste onto one side of the raw sheet using known methods such as screen printing, and then drying to form a dry film. Furthermore, from the viewpoint of the requirement for thinning of the internal electrode layer 11, it is preferable that the thickness of the dried film after drying is 1 μm or less.

[0133] Next, the green sheet is peeled off from the support film and laminated with alternating dielectric layers composed of the green sheet and dry films formed on one side of the green sheet. The laminate is then subjected to heating and pressurization to obtain a laminate. Alternatively, a protective green sheet without conductive paste can be further disposed on both sides of the laminate.

[0134] Next, the laminate is cut to a predetermined size to form a green chip, and the green chip is subjected to a binder removal process and fired in a reducing atmosphere to manufacture the ceramic laminate 10. Furthermore, the atmosphere for the binder removal process is preferably atmospheric or N2 gas atmosphere. The temperature for the binder removal process is, for example, 200°C or higher and 400°C or lower. Additionally, it is preferable that the holding time at the above-mentioned temperature during the binder removal process is 0.5 hours or higher and 24 hours or lower. Furthermore, firing is performed in a reducing atmosphere to suppress oxidation of the metal used for the internal electrode layer; the firing temperature for the laminate is, for example, 1000°C or higher and 1350°C or lower, and the holding time at the temperature during firing is, for example, 0.5 hours or higher and 8 hours or lower.

[0135] By firing the green chip, the organic binder in the green chip is completely removed, and the ceramic raw material powder is fired to form a ceramic dielectric layer 12. Additionally, the organic carrier in the dried film is removed, and nickel powder or a nickel-based alloy powder is sintered or melted and integrated to form an internal electrode layer 11, thereby forming a multilayer ceramic body consisting of alternating layers of dielectric layer 12 and internal electrode layer 11. Furthermore, from the viewpoint of improving reliability by introducing oxygen into the interior of the dielectric layer and suppressing the re-oxidation of the internal electrode, the fired multilayer ceramic body can also be annealed.

[0136] Then, a multilayer ceramic capacitor 1 is manufactured by providing a pair of external electrodes 20 to the prepared multilayer ceramic sintered body. For example, the external electrodes 20 include an external electrode layer 21 and an electroplated layer 22. The external electrode layer 21 is electrically connected to the internal electrode layer 11. Furthermore, copper, nickel, or alloys thereof can preferably be used as the material for the external electrodes 20. In addition, the electronic component is not limited to a multilayer ceramic capacitor, but can also be an electronic component other than a multilayer ceramic capacitor, such as a rheostat.

[0137] Example The present invention will now be described in detail based on embodiments and comparative examples, but the present invention is not limited to any of the embodiments.

[0138] [Making of the carrier] The following describes how cellulose-based compounds and polyvinyl acetal-based compounds were synthesized, and then bonded together to synthesize a polymer compound, thus creating a carrier.

[0139] (Synthesis of cellulose compounds (1a) containing vinyl groups) Ethyl cellulose (ETHOCEL STD-100 manufactured by Dow Chemical, number average molecular weight Mn (based on GPC standard polystyrene conversion): 63420, average number of non-etherified hydroxyl groups in the cyclic structure of the glucose ring: 0.48) was prepared and dried. Here, drying of the ethyl cellulose was performed to remove adsorbed moisture. Drying was carried out under reduced pressure at room temperature.

[0140] 100 parts by mass of the dried ethyl cellulose was dissolved in 900 parts by mass of ethyl acetate to obtain a solution. 0.17 parts by mass of 3-allyloxypropionic acid (equivalent to an average of one vinyl group introduced per molecule of ethyl cellulose), 0.20 parts by mass of diisopropylcarbodiimide as a condensing agent, and 0.004 parts by mass of dimethylaminopyridine as a reaction promoter were added to the obtained solution, and the reaction was carried out by stirring at 40°C for 5 hours. Afterwards, by removing the ethyl acetate, a cellulose compound (1a) with a vinyl group introduced into ethyl cellulose was obtained as a solid.

[0141] Analysis of a portion of the solid obtained by FT-IR and 1H-NMR confirmed the formation of ester bonds and the introduction of vinyl groups into ethyl cellulose in the same molar amount as the added 3-allyloxypropionic acid.

[0142] Furthermore, in the cellulose compound (1a), in addition to the compound into which vinyl groups are introduced, unreacted ethyl cellulose is mixed in; in the examples, the mixture of these is used as the cellulose compound (1a). The same applies to the cellulose compound (2a) described later.

[0143] (Synthesis of polyvinyl butyral compounds with thiol groups (1b)) Polyvinyl butyral (BM-SZ manufactured by Sekisui Chemicals Co., Ltd., number-average molecular weight Mn (based on GPC standard polystyrene conversion): 55000, hydroxyl content: approximately 22 mol%) was prepared and dried. Drying of polyvinyl butyral was performed to remove adsorbed moisture. Drying was carried out under reduced pressure at room temperature. 100 parts by mass of the dried polyvinyl butyral was dissolved in 900 parts by mass of ethyl acetate. 0.20 parts by mass of 3-mercaptopropionic acid (equivalent to an average introduction of one thiol group per molecule of polyvinyl butyral), 0.24 parts by mass of diisopropylcarbodiimide as a condensing agent, and 0.005 parts by mass of dimethylaminopyridine as a reaction promoter were added to the resulting solution, and the reaction was carried out by stirring at 40°C for 5 hours. Afterwards, by removing ethyl acetate, a polyvinyl butyral compound (1b) with thiol groups introduced into polyvinyl butyral was obtained as a solid.

[0144] When a portion of the solid was analyzed by FT-IR and 1H-NMR, the formation of ester bonds was confirmed, and the same molar amount of thiol groups as the added 3-mercaptopropionic acid was confirmed to be introduced into polyvinyl butyral.

[0145] Furthermore, in the polyvinyl butyral compound (1b), in addition to the compound to which a thiol group has been introduced into polyvinyl butyral, unreacted polyvinyl butyral is mixed in. In the examples, the mixture of these compounds is used as the polyvinyl butyral compound (1b). The same applies to the polyvinyl butyral compound (2b) described later.

[0146] (Synthesis of cellulose compounds (2a) containing vinyl groups) Cellulose compound (2a) was synthesized in the same manner as cellulose compound (1a), except that 3-allyloxypropionic acid, which is equivalent to two average introduction amounts relative to one molecule of ethyl cellulose, was added.

[0147] (Synthesis of polyvinyl butyral compounds with thiol groups (2b)) Except for the addition of 3-mercaptopropionic acid, which is equivalent to two average amounts introduced relative to one molecule of polyvinyl butyral, polyvinyl butyral compound (2b) was synthesized in the same manner as polyvinyl butyral compound (1b).

[0148] (Making of Carrier 1) Five parts by mass of cellulose-based compound (1a) and 4.35 parts by mass of polyvinyl butyral-based compound (1b) were dissolved in 60 parts by mass of isobornyl acetate solvent. The solution was transferred to a glass flask reaction vessel. After nitrogen replacement, 0.1 parts by mass of azobisisobutyronitrile was added as a free radical initiator. The reaction was carried out at 80°C for 3 hours with stirring to obtain a support 1 containing polymer 1. Here, the cellulose-based compound (1a) and polyvinyl butyral-based compound (1b) were in the same molar amount. In support 1, polymer 1 contained 13.5% by mass. Furthermore, polymer 1 contained a mixture of polymers bonded together from cellulose-based compound (1a) and polyvinyl butyral-based compound (1b) and unreacted ethyl cellulose or unreacted polyvinyl butyral; in this example, a mixture of these was used as polymer 1. Additionally, the HSP δh of isobornyl acetate was 3.0 MPa. 0.5 .

[0149] Analysis of the synthesized polymer compound 1 by FT-IR and 1H-NMR confirmed the presence of -S- bonds, yielding the target structure. Furthermore, the weight-average molecular weight (Mw: GPC-based standard polystyrene conversion value) of polymer compound 1 was determined. Moreover, in tests to dissolve the resin using 20 solvents with known HSP values, the δh of the HSP of polymer compound 1, calculated using the HSP values ​​of the soluble solvents and HSP version 5, was found to be 7.61 MPa. 0.5 .

[0150] (Making of Carrier 2) Polymer compound 2, synthesized from cellulose-based compound (2a) and polyvinyl butyral-based compound (2b), was also synthesized in the same manner as polymer compound 1, resulting in carrier 2. Furthermore, the content of polymer compound 2 in carrier 2 was 13.5% by mass. In addition, polymer compound 2, like polymer compound 1, contained a mixture of a polymer formed by the bonding of cellulose-based compound (2a) and polyvinyl butyral-based compound (2b) and unreacted ethyl cellulose or unreacted polyvinyl butyral; in the examples, this mixture was used as polymer compound 2.

[0151] When polymer 2 was synthesized and analyzed by FT-IR and 1H-NMR in the same manner as polymer 1, -S- bonds were confirmed, and the target structure was obtained. Furthermore, the weight-average molecular weight (Mw: GPC-based standard polystyrene conversion value) of polymer 2 was determined. Moreover, the δh of the HSP of polymer 2, calculated using the same method as polymer 1, was 7.63 MPa. 0.5 .

[0152] (Making of Carrier 3) Five parts by mass of cellulose-based compound (1a) and 4.35 parts by mass of polyvinyl butyral-based compound (1b) were dissolved in 60 parts by mass of dihydroterpineol solvent. The solution was transferred to a glass flask reaction vessel. After nitrogen replacement, 0.1 parts by mass of azobisisobutyronitrile was added as a free radical initiator. The reaction was carried out at 80°C for 3 hours with stirring to obtain a support 3 containing polymer 3. Here, the cellulose-based compound (1a) and polyvinyl butyral-based compound (1b) were in the same molar amount. In support 3, polymer 3 comprised 13.5% by mass. Furthermore, polymer 3 contained a mixture of polymers bonded together from cellulose-based compound (1a) and polyvinyl butyral-based compound (1b) and unreacted ethyl cellulose or unreacted polyvinyl butyral; in this example, a mixture of these was used as polymer 3. Additionally, the δh of the HSP of dihydroterpineol was 6.7 MPa. 0.5 .

[0153] When polymer 3 was synthesized and analyzed by FT-IR and 1H-NMR in the same manner as polymer 1, -S- bonds were confirmed, and the target structure was obtained. Furthermore, the weight-average molecular weight (Mw: GPC-based standard polystyrene conversion value) of polymer 3 was determined. Moreover, the δh of the HSP of polymer 3, calculated using the same method as polymer 1, was 7.62 MPa. 0.5 .

[0154] Table 1 shows the characteristics of the cellulose-based compounds (1a), cellulose-based compounds (2a), and polyvinyl acetal-based compounds (1b) and polyvinyl acetal-based compounds (2b) contained in the carriers 1 to 3. Table 2 shows the weight-average molecular weight of the polymers 1 to 3, as well as the names and δh values ​​of the organic solvents contained in the carriers 1 to 3.

[0155] [Table 1]

[0156] [Table 2]

[0157] [Example 1] Example 1 illustrates the preparation of a conductive slurry using carrier 1 as follows, and the evaluation of physical properties such as sheet erosion, surface roughness, and dry film density using the resulting conductive slurry. Here, carrier 1 comprises a polymer compound 1, a polymer of cellulose-based and polyvinyl acetal-based compounds bonded together by sulfur atoms, as an adhesive resin. Furthermore, the hydrogen bonding term δh, which includes the Hansen solubility parameter, is 3.0 MPa. 0.5 (6.5MPa) 0.5 Isobornyl acetate (hereinafter) is used as the organic solvent. In polymer compound 1, the molar ratio of sulfur atoms to cellulose-based compounds is 1.

[0158] <Preparation of Conductive Paste> The conductive slurry of Example 1 was prepared by mixing 47% by mass of Ni powder, 4.7% by mass of ceramic powder, 26.67% by mass of carrier 1, 0.4% by mass of an anionic dispersant of amino acid and fatty acid amide compounds (hereinafter, sometimes referred to as "dispersant A"), and the balance organic solvent (isobornyl acetate) in a manner that is 100% by mass.

[0159] (Conductive powder) Ni powder (with a number-average particle size of 0.2 μm as measured by SEM) was used as the conductive powder in the preparation of the conductive paste.

[0160] (Ceramic powder) Barium titanate (BaTiO3, with a number-average particle size of 0.05 μm as determined by SEM) was used as the ceramic powder in the preparation of the conductive paste.

[0161] [Evaluation Method] (Sheet erosion, surface roughness of the dried film, density of the dried film) The surface roughness and density of the dried film obtained by eroding the prepared conductive paste sheet and drying the conductive paste were evaluated as follows.

[0162] <Sheet Erosion> The conductive paste prepared for printing on a 2μm thick green sheet (containing barium titanate (BT, BaTiO3) and polyvinyl butyral resin) was dried at 80°C for 3 minutes. Immediately after drying, the surface of the green sheet opposite the printing surface was observed under a microscope to confirm the presence or absence of the swelling phenomenon characteristic of sheet etching. If no swelling phenomenon was observed, the rating was ○ (Good); if swelling phenomenon was observed, the rating was × (Poor).

[0163] <Surface Roughness> A conductive paste was screen-printed onto a 2.54 cm (1 inch) square sheet of heat-resistant tempered glass and dried at 120°C for 1 hour in the atmosphere, resulting in a 20 mm square film with a thickness of 1–3 μm. When the conductive paste was well dispersed, the surface of the dried film was smooth. In cases of poor dispersion, agglomeration occurred within the conductive paste, resulting in a rough surface and reduced smoothness. Therefore, the surface roughness Sa (arithmetic mean height) of the dried film was measured using a laser microscope (Keyence VK-X120) according to ISO 25178 standards. A smaller surface roughness Sa (arithmetic mean height) value indicates a smoother surface of the dried film.

[0164] <Dry film density> The prepared conductive paste was placed on a PET film and extended to a length of approximately 100 mm using a coater with a width of 50 mm and a gap of 125 μm. The resulting PET film was dried at 120 °C for 40 minutes to form a dried body. The dried body was then cut into four pieces at a square of 2.54 cm (1 inch). The thickness and weight of each of the four dried films were measured based on the peeled PET film, and the density of the dried film (average value) was calculated.

[0165] [Comparative Example 1] Comparative Example 1 is an example in which a conductive slurry was prepared using carrier 2 in the same manner as in Example 1, and the resulting conductive slurry was used to evaluate physical properties such as sheet erosion, surface roughness, and dry film density. Here, carrier 2 comprises a polymer compound 2 formed by the bonding of cellulose-based compounds and polyvinyl acetal-based compounds through sulfur atoms as an adhesive resin. Furthermore, the hydrogen bonding term δh, which includes the Hansen solubility parameter, is 3.0 MPa. 0.5 (6.5MPa) 0.5 Isoborneol acetate (as follows) is used as the organic solvent. In polymer compound 2, the molar ratio of sulfur atoms to cellulose-based compounds is 2.

[0166] <Preparation and Property Evaluation of Conductive Paste> Except for using carrier 2, the conductive paste involved in Comparative Example 1 was prepared in the same manner as in Example 1, and the sheet erosion, surface roughness of the dried film, and density of the dried film were evaluated in the same manner as in Example 1.

[0167] [Comparative Example 2] Comparative Example 2 is an example in which a conductive slurry was prepared using carrier 3 in the same manner as in Example 1, and the resulting conductive slurry was used to evaluate physical properties such as sheet erosion, surface roughness, and dry film density. Here, carrier 3 comprises a polymer compound 3 formed by the bonding of cellulose-based compounds and polyvinyl acetal-based compounds through sulfur atoms as an adhesive resin. Furthermore, the hydrogen bonding term δh, which includes the Hansen solubility parameter, is 6.7 MPa. 0.5 Dihydroterpineol is used as an organic solvent. In polymer compound 3, the molar ratio of sulfur atoms to cellulose-based compounds is 3.

[0168] Except for using carrier 3 and using dihydroterpineol as the remaining organic solvent, the conductive paste involved in Comparative Example 2 was prepared in the same manner as in Example 1, and the sheet erosion, surface roughness of the dried film, and density of the dried film were evaluated in the same manner as in Example 1.

[0169] [Comparative Example 3] Comparative Example 3 is an example of using ethyl cellulose and polyvinyl butyral resin to prepare a conductive paste without using carriers 1 to 3 and without containing polymer compounds. The resulting conductive paste was used to evaluate physical properties such as sheet erosion, surface roughness, and dry film density. Furthermore, in the preparation of the conductive paste, the hydrogen bonding term δh using the Hansen solubility parameter was 3.0 MPa. 0.5 (6.5MPa) 0.5 Isoborneol acetate (as follows) is used as an organic solvent.

[0170] (Fabrication of carrier 4a) Organic carrier 4a was prepared by dissolving 5 parts by mass of ethyl cellulose (ETHOCEL STD-100 manufactured by Dow Chemical) in 30 parts by mass of isoborneol acetate.

[0171] (Fabrication of carrier 4b) Carrier 4b was prepared by dissolving 4.35 parts by weight of polyvinyl butyral resin ("BM-SZ" manufactured by Sekisui Chemicals Co., Ltd.) in 30 parts by weight of isoborneol acetate.

[0172] (Making of Carrier 4) Organic carrier 4 was adjusted by mixing organic carrier 4a and organic carrier 4b in equal amounts.

[0173] <Preparation of Conductive Paste> The conductive paste described in Comparative Example 3 was prepared by mixing 47% Ni powder, 4.7% ceramic powder, 26.67% carrier 4, 0.4% dispersant A, and the balance organic solvent (isobornyl acetate) in a manner that is 100% by weight.

[0174] Using the prepared conductive paste, the sheet erosion, surface roughness of the dried film, and density of the dried film were evaluated in the same manner as in Example 1.

[0175] [Comparative Example 4] Comparative Example 4 is an example of preparing a conductive paste using ethyl cellulose and polyvinyl butyral resin without using carriers 1 to 3 and without containing polymer compounds. The resulting conductive paste was used to evaluate physical properties such as sheet erosion, surface roughness, and dry film density. Furthermore, in the preparation of the conductive paste, the hydrogen bonding term δh using the Hansen solubility parameter was 6.7 MPa. 0.5 Dihydroterpineol is used as an organic solvent.

[0176] (Fabrication of carrier 5a) Organic carrier 5a was prepared by dissolving 5 parts by weight of ethyl cellulose (ETHOCEL STD-100 manufactured by Dow Chemical) in 30 parts by weight of dihydroterpene alcohol.

[0177] (Fabrication of carrier 5b) Carrier 5b was prepared by dissolving 4.35 parts by weight of polyvinyl butyral resin ("BM-SZ" manufactured by Sekisui Chemicals Co., Ltd.) in 30 parts by weight of dihydroterpene alcohol.

[0178] (Making of Carrier 5) Organic carrier 5 was adjusted by mixing carrier 5a and organic carrier 5b in equal amounts.

[0179] <Preparation of Conductive Paste> The conductive paste described in Comparative Example 4 was prepared by mixing 47% Ni powder, 4.7% ceramic powder, 26.67% carrier 5, 0.4% dispersant A, and the balance organic solvent (dihydroterpineol) in a manner that is 100% by weight.

[0180] Using the prepared conductive paste, the sheet erosion, surface roughness of the dried film, and density of the dried film were evaluated in the same manner as in Example 1.

[0181] Table 3 shows the names of the organic solvents contained in the conductive pastes of Examples 1, Comparative Examples 1 to 4, the values ​​of δh, the types of adhesive resins, and the evaluation results of sheet erosion, surface roughness, and dry film density.

[0182] [Table 3]

[0183] [Evaluation Results] The dried film formed using the conductive paste of Example 1, as shown in Table 3, has a surface roughness Sa (arithmetic mean height) of 90 nm, which is the lowest compared to the comparative examples. Furthermore, the dried film density of the conductive paste of Example 1 is also 5.51 g / cm³. 3 Furthermore, the conductive paste of Example 1 does not cause sheet erosion. That is, if it is the conductive paste of Example 1, it results in no sheet erosion of the green sheet and the formation of a dry film with good smoothness and dry film density.

[0184] On the other hand, in the case of the conductive slurry of Comparative Example 1, where the number of functional groups of polymer compound 2 is 2, the surface roughness and dry film density of the obtained dried film were worse than those of Example 1. Furthermore, in the case of the conductive slurry of Comparative Example 3, which uses common ethyl cellulose and polyvinyl butyral resins as the adhesive resin and isoborneol acetate as a solvent that does not cause sheet erosion, although sheet erosion did not occur, the surface roughness was the worst among Examples 1 and Comparative Examples 1 to 4. Additionally, in the case of the conductive slurry of Comparative Example 4, which uses common ethyl cellulose and polyvinyl butyral resins as the adhesive resin and dihydroterpineol as the adhesive resin, sheet erosion occurred, further resulting in surface roughness and dry film density that were worse than those of Example 1.

[0185] Industrial applicability This embodiment provides a conductive paste that, when used with finely ground conductive powder or ceramic powder, does not cause sheet erosion of the green sheet, produces a smooth dried film, and exhibits excellent adhesion. Therefore, it is particularly advantageous as a raw material for use as an internal electrode in multilayer ceramic capacitors, which are chip components (electronic components) in electronic devices such as mobile phones and digital devices, and is industrially useful.

[0186] Explanation of reference numerals in the attached figures: 1: Multilayer ceramic capacitor; 10: Ceramic multilayer; 11: Internal electrode layer; 12: Dielectric layer; 20: External electrode; 21: External electrode layer; 22: Electroplated layer.

Claims

1. A carrier comprising an adhesive resin and an organic solvent, wherein, The adhesive resin comprises a polymeric compound consisting of cellulose-based compounds and polyvinyl acetal-based compounds bonded together by sulfur atoms. The molar ratio of sulfur atoms in the polymer compound to those in the cellulose-based compound is 0.3 to 1.

7. The hydrogen bonding term δh of the Hansen solubility parameter of the organic solvent is 6.5 MPa. 0.5 the following.

2. The carrier according to claim 1, wherein, The hydrogen bonding term δh of the Hansen solubility parameter of the polymer compound is 6.5~8.5 MPa. 0.5 .

3. The carrier according to claim 1 or 2, wherein, The cellulose-based compounds are cellulose derivatives containing thiol or vinyl groups. The polyvinyl acetal compounds are polyvinyl acetal resins containing thiol groups or vinyl groups. When the cellulose derivative has a thiol group, the polyvinyl acetal resin has a vinyl group that reacts with the thiol group. When the cellulose derivative contains vinyl groups, the polyvinyl acetal resin contains thiol groups that react with the vinyl groups.

4. The carrier according to claim 3, wherein, The cellulose derivative is ethyl cellulose containing thiol or vinyl groups. The polyvinyl acetal resin is polyvinyl butyral containing thiol groups or vinyl groups.

5. The carrier according to claim 1 or 2, wherein, The cellulose-based compound is a first esterification product formed by the dehydration condensation of the carboxyl group of a carboxylic acid containing a thiol group or a vinyl group and the hydroxyl group of cellulose. The polyvinyl acetal compounds are second esterification products formed by the dehydration condensation of the carboxyl group of a carboxylic acid containing a thiol group or a vinyl group and the hydroxyl group of a polyvinyl acetal. If the first esterification reactant has a thiol group, the second esterification reactant has a vinyl group. If the first esterification reactant contains a vinyl group, the second esterification reactant contains a thiol group. The polymer compound is a thiol-ene reactant of the first esterification reactant and the second esterification reactant.

6. The carrier according to claim 5, wherein, The first esterification product is an esterification product formed by the dehydration condensation of the carboxyl group of 3-allyloxypropionic acid and the hydroxyl group of ethyl cellulose. The second esterification product is an esterification product formed by the dehydration condensation of the carboxyl group of 3-mercaptopropionic acid and the hydroxyl group of polyvinyl butyral.

7. A conductive paste comprising the carrier, conductive powder, and ceramic powder as described in claim 1 or 2, wherein, The hydrogen bonding term δh of the Hansen solubility parameter of the organic solvent in the conductive slurry is 6.5 MPa. 0.5 the following.

8. The conductive paste according to claim 7, wherein, The number-average particle size of the conductive powder is greater than 0.05 μm and less than 1.0 μm.

9. The conductive paste according to claim 7, wherein, The ceramic powder contains barium titanate.

10. The conductive paste according to claim 7, wherein, The number-average particle size of the ceramic powder is greater than 0.01 μm and less than 0.5 μm.

11. The conductive paste according to claim 7, wherein, The content of the ceramic powder is more than 1% by mass and less than 20% by mass.

12. The conductive paste according to claim 7, wherein, The conductive paste is used for the internal electrodes of the laminated ceramic component.

13. An electronic component, wherein, The electronic component is formed using the conductive paste of claim 7.

14. A multilayer ceramic capacitor, wherein, The multilayer ceramic capacitor has at least one stacked body formed by stacking a dielectric layer and an internal electrode layer. The internal electrode layer is formed using the conductive paste of claim 7.

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