Conductive paste, electron component, and lamination ceramic capacitor

Abstract

To provide: an electrically conductive paste that uses an electrically conductive powder and a ceramic powder that are fined in order to reduce a size and a reduce a thickness of a lamination ceramic electron component and that includes a smooth dry film and can form an internal electrode layer having an excellent adhesion in the electrically conductive paste ; an electron component, and a lamination ceramic capacitor.SOLUTION: An electrically conductive paste contains: an electrically conductive powder; a ceramic powder; a dispersant; a binder resin; and an organic solvent. The binder resin contains a high-molecular compound obtained by coupling a cellulose-based compound and a polyvinyl acetal-based compound by a sulfur atom. A mol ratio of the sulfur atom contained into the polymer compound to the cellulose-based compound is 0.3 to 1.7. A weight average molecular weight of the polymer compound is 300,000 or more and less than 150,000.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a conductive paste, an electronic component, and a multilayer ceramic capacitor.

Background Art

[0002] With the miniaturization and high performance of electronic devices such as mobile phones and digital devices, miniaturization and high capacitance are also desired for electronic components including multilayer ceramic capacitors. A multilayer ceramic capacitor has a structure in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately laminated, and by thinning these dielectric layers and internal electrode layers, miniaturization and high capacitance can be achieved.

[0003] A multilayer ceramic capacitor is manufactured, for example, as follows. First, a conductive paste for an internal electrode is printed (applied) in a predetermined electrode pattern on the surface of a green sheet containing a dielectric powder such as barium titanate (BaTiO3) and a binder resin such as polybutyral resin (PVB), and dried to form a dry film. Next, a laminate is formed in a state where the dry film and the green sheet are alternately laminated and integrally formed by heat pressing. The laminate is cut, and after performing a deorganic binder treatment in an oxidizing atmosphere or an inert atmosphere, firing is performed to obtain a fired chip. Next, an external electrode paste is applied to both ends of the fired chip, and after firing, nickel plating or the like is applied to the surface of the external electrode to obtain a multilayer ceramic capacitor (MLCC). The conductive paste for the internal electrode contains a conductive powder such as nickel powder, a ceramic powder such as barium titanate powder, an organic binder, and a solvent.

[0004] In recent years, further miniaturization and high capacitance have been demanded for MLCCs. For example, for internal electrodes using nickel or the like, thinning of an electrode film with excellent density and continuity, and for ceramic dielectric materials and dielectric layers using them, an increase in dielectric constant and thinning have been studied, and those with a dielectric layer thickness of 1.0 μm or less have already been put into practical use. And for the electrode layer, it is also desired to make it 1.0 μm or less.

[0005] As the internal electrode layer becomes thinner, unevenness tends to occur on the surface of the electrode layer, and it is said that the electric field concentrates on the convex portions of the electrode layer, causing the insulation resistance of the dielectric layer to decrease. Therefore, further smoothing of the electrode layer surface is required.

[0006] In addition, when the MLCC becomes thinner, the adhesion between the green sheet and the internal electrode layer decreases, resulting in problems such as frequent curling and lamination misalignment due to insufficient adhesion during lamination.

[0007] This poor adhesion causes, for example, short-circuit failures in multilayer ceramic capacitors. In particular, due to the demand for multilayer MLCCs, it is necessary to reduce the thickness of the dielectric layer per layer using fine particle dielectric powder and increase the number of layers. Therefore, improvement of this poor adhesion is desired. If the adhesion between the green sheets is weak, it causes structural defects such as delamination, voids, and cracks during firing, reducing the yield of MLCCs.

[0008] To improve such poor adhesion, when laminating a plurality of ceramic green sheets formed with a conductive paste film, by smoothing the surface of the coating film made of the conductive paste, the contact area between the conductive paste film and the ceramic green sheet can be increased, and as a result, the adhesion can be improved.

[0009] Therefore, cellulose-based resins such as ethyl cellulose (EC) have mainly been used as organic binders. Cellulose-based resins have high compatibility with various solvents used in conductive pastes and can impart the desired rheological properties to the conductive paste, which is effective for smoothing the surface of the coating film made of the conductive paste. On the other hand, cellulose-based resins do not have much thermoplasticity, so the dried portion of the conductive paste does not have adhesion to the upper green sheet during thermocompression bonding.

[0010] Therefore, when using a butyral resin as the binder resin of the conductive paste, the adhesion between the internal electrode and the green sheet can be improved. Patent Document 1 discloses that it is preferable to use a mixed system of ethyl cellulose and polyvinyl butyral as the organic binder resin of the paste for internal electrodes.

[0011] However, when the conductive paste for internal electrodes contains polyvinyl butyral, a solvent capable of dissolving polyvinyl butyral has to be used as the solvent of the conductive paste. Therefore, the polyvinyl butyral contained in the green sheet may also be dissolved by the solvent contained in the conductive paste, resulting in sheet attack. When sheet attack occurs, the thickness of the green sheet may become locally thinner or holes may open in the green sheet, which may cause poor formation of the internal electrode or disappearance of the green sheet between the internal electrodes, leading to connection of the internal electrodes and occurrence of a short circuit. In consideration of this, Patent Document 2 discloses a special solvent composition capable of coping with sheet attack.

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0013] Generally, when two organic binder resins with significantly different structures are mixed, most combinations are incompatible (non-compatible). In the case of an incompatible combination of two organic binder resins, since the two organic binder resins basically do not dissolve and exist independently, the performance expected by using the two organic binder resins may not be exhibited, or the function may be significantly reduced compared to the case of using each organic binder alone.

[0014] In addition, when it becomes difficult for the resin to dissolve in the solvent, the smoothness of the paste dry film deteriorates. For example, when ethyl cellulose and polyvinyl butyral are mixed, since they are incompatible, a typical "sea-island structure" is observed and phase separation is confirmed. As a result, the distribution of inorganic particles (conductive particles, ceramic powder) in the dry film becomes non-uniform. Thus, the combination of organic materials in the paste composition affects the dispersibility of inorganic particles (conductive particles, ceramic powder) in the dry film.

[0015] If organic binder resins that do not originally mix with each other can be made compatible with each other, the characteristics of both can be combined, the interface between different polymers can be stabilized, and a uniform and stable dispersion state can be achieved.

[0016] In addition, in the conductive pastes disclosed in Patent Documents 1 and 2, since polyvinyl butyral resin is contained, the adhesion between the dry film and the green sheet can be improved. However, because a cellulose-based resin and a polyvinyl butyral resin are used in combination, due to the poor compatibility of both resins, the dispersion of conductive powder and ceramic powder in the conductive paste may be insufficient, or the density and smoothness of the dry film of the conductive paste may be insufficient.

[0017] In view of such a situation, an object of the present invention is to provide a conductive paste, an electronic component, and a multilayer ceramic capacitor that have a smooth dry film and excellent adhesion in a conductive paste using fine conductive powder or ceramic powder for miniaturization and thinning of multilayer ceramic electronic components, and that can form an internal electrode layer.

Means for Solving the Problems

[0018] To solve the above problems, the conductive paste of the present invention contains conductive powder, ceramic powder, a dispersant, a binder resin, and an organic solvent. The binder resin contains a polymer compound in which a cellulose-based compound and a polyvinyl acetal-based compound are bonded by a sulfur atom. The molar ratio of the sulfur atoms contained in the polymer compound to the cellulose-based compound is 0.3 to 1.7, and the weight average molecular weight of the polymer compound is 30,000 or more and less than 150,000.

[0019] The weight average molecular weight of the polymer compound may be 60,000 or more and 130,000 or less.

[0020] The cellulose-based compound is a cellulose derivative having a thiol group or a vinyl group, and the polyvinyl acetal-based compound is a polyvinyl acetal resin having a thiol group or a vinyl group. 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 may have a thiol group that reacts with the vinyl group.

[0021] The cellulose derivative is ethyl cellulose having a thiol group or a vinyl group, and the polyvinyl acetal resin may be polyvinyl butyral having a thiol group or a vinyl group.

[0022] The cellulose-based compound is a first esterification reactant obtained by dehydration condensation of the carboxyl group of a carboxylic acid having a thiol group or a vinyl group and the hydroxyl group of cellulose. The polyvinyl acetal-based compound is a second esterification reactant obtained by dehydration condensation of the carboxyl group of a carboxylic acid having a thiol group or a vinyl group and the hydroxyl group of polyvinyl acetal. When the first esterification reactant has a thiol group, the second esterification reactant has a vinyl group. When the first esterification reactant has a vinyl group, the second esterification reactant has a thiol group. The polymer compound may be a thiol-ene reactant of the first esterification reactant and the second esterification reactant.

[0023] The first esterification reactant may be an esterification reactant obtained by dehydration condensation of the carboxyl group of 3-allyloxypropionic acid and the hydroxyl group of ethyl cellulose. The second esterification reactant may be an esterification reactant obtained by dehydration condensation of the carboxyl group of 3-mercaptopropionic acid and the hydroxyl group of polyvinyl butyral.

[0024] The binder resin may contain at least one of cellulose and polyvinyl acetal.

[0025] The conductive powder may be nickel powder.

[0026] The number average particle diameter of the conductive powder may be 0.05 μm or more and 0.3 μm or less.

[0027] The ceramic powder may contain barium titanate.

[0028] The number average particle diameter of the ceramic powder may be 0.01 μm or more and 0.5 μm or less.

[0029] The content of the ceramic powder may be 1% by mass or more and 20% by mass or less.

[0030] The conductive paste of the present invention may be used for the internal electrodes of multilayer ceramic components.

[0031] Also, 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.

[0032] Also, in order to solve the above problems, the multilayer ceramic capacitor of the present invention has at least a laminate in which dielectric layers and internal electrode layers are laminated, and the internal electrode layer is a multilayer ceramic capacitor formed using the conductive paste of the present invention.

Advantages of the Invention

[0033] The conductive paste of the present invention is excellent in the dispersibility of conductive powder and has high surface smoothness in the dried film after coating. Further, the electrode pattern of an electronic component such as a multilayer ceramic capacitor formed using the conductive paste of the present invention is excellent in the adhesion of the conductive paste even when forming a thin film electrode.

Brief Description of the Drawings

[0034]

Figure 1

Modes for Carrying Out the Invention

[0035] Hereinafter, an embodiment of the conductive paste, the electronic component, and the multilayer ceramic capacitor of the present invention will be described.

[0036] [Conductive Paste] The conductive paste of the present embodiment contains conductive powder, ceramic powder, a dispersant, a binder resin, and an organic solvent. Hereinafter, each component will be described in detail.

[0037] (Conductive Powder) The conductive powder is not particularly limited, and metal powders can be used. For example, one or more powders selected from Ni, Pd, Pt, Au, Ag, Cu, and alloys thereof can be used. Among these, from the viewpoints of conductivity, corrosion resistance, and cost, powders of Ni or its alloys are preferred. As the Ni alloy, for example, an alloy (Ni alloy) of Ni and at least one element selected from the group consisting of Mn, Cr, Co, Al, Fe, Cu, Zn, Ag, Au, Pt, and Pd can be used. The content of Ni in the Ni alloy is, for example, 50% by mass or more, preferably 80% by mass or more. Further, the Ni powder may contain about several hundred ppm of S in order to suppress the sudden gas generation due to the partial thermal decomposition of the binder resin during the debinding process.

[0038] The method for producing the conductive powder is not particularly limited. For example, a method of directly depositing chloride vapor from the gas phase in hydrogen gas, an atomization method from molten metal, a spray pyrolysis method using an aqueous solution, a wet method of reducing a metal salt of a raw material in an aqueous solution, etc. can be applied.

[0039] The number average particle diameter of the conductive powder is not particularly limited and may be selected according to the size of the electronic component to be used, etc. The number average particle diameter of the conductive powder is, for example, preferably 0.3 μm or less, more preferably 0.2 μm or less, for use in multilayer ceramic capacitors with increasing film thickness. When the average particle diameter exceeds 0.3 μm, the unevenness on the surface of the internal electrode becomes severe, and the electrical characteristics of the capacitor may be deteriorated, which is not preferable. Further, the lower limit of the average particle diameter of the conductive powder is not particularly limited, but is, for example, 0.05 μm or more. When the number average particle diameter is less than 0.05 μm, handling becomes extremely difficult.

[0040] The number average particle diameter of the conductive powder is a value obtained from observations by a scanning electron microscope (SEM). It is the average value obtained by measuring the particle diameter of each of a plurality of particles from an image observed at a magnification of 10,000 times with an SEM.

[0041] The content of the conductive powder is preferably 30% by mass or more and less than 70% by mass, more preferably 40% by mass or more and 60% by mass or less, based on the total amount of the conductive paste. When the content of the conductive powder is 30% by mass or more and less than 70% by mass based on the total amount of the conductive paste, the conductivity and dispersibility are excellent.

[0042] (Ceramic powder) The ceramic powder is not particularly limited. For example, when it is a conductive paste for an internal electrode of a multilayer ceramic capacitor, known ceramic powders are appropriately selected depending on the type of the multilayer ceramic capacitor to be applied. Examples of the ceramic powder include perovskite-type oxides containing Ba and Ti, preferably barium titanate (BaTiO3).

[0043] As the ceramic powder, a ceramic powder containing barium titanate as a main component and an oxide as a sub-component may be used. Examples of the oxide include oxides of Mn, Cr, Si, Ca, Ba, Mg, V, W, Ta, Nb, and one or more rare earth elements. Further, as the ceramic powder, for example, a perovskite-type oxide ferroelectric ceramic powder in which Ba atoms or Ti atoms of barium titanate (BaTiO3) are substituted with other atoms such as Sn, Pb, Zr, etc. may be used.

[0044] In the conductive paste for an internal electrode, a powder having the same composition as the dielectric ceramic powder constituting the green sheet of the multilayer ceramic capacitor may be used as the ceramic powder. Thereby, the generation of cracks due to the shrinkage mismatch at the interface between the dielectric layer and the internal electrode layer in the sintering process is suppressed. Examples of such ceramic powders include oxides such as ZnO, ferrite, PZT, BaO, Al2O3, Bi2O3, R (rare earth element) 2O3, TiO2, Nd2O3, etc., in addition to the above. Note that one type of ceramic powder may be used, or two or more types may be used.

[0045] The number average particle diameter 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. When the number average particle diameter of the ceramic powder is 0.01 μm or more and 0.5 μm or less, a sufficiently thin and uniform internal electrode can be formed when used as a paste for an internal electrode. The number average particle diameter is a value obtained from observations by a scanning electron microscope (SEM). It is the average value obtained by measuring the particle diameter of each of a plurality of particles from an image observed at a magnification of 50,000 times with an SEM.

[0046] The content of the ceramic powder is preferably 1 part by mass or more and 30 parts by mass or less, more preferably 3 parts by mass or more and 30 parts by mass or less, with respect to 100 parts by mass of the conductive powder. When the content of the conductive powder is 1 part by mass or more and 30 parts by mass or less, it has excellent conductivity and dispersibility.

[0047] The content of the ceramic powder 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, with respect to the total amount of the conductive paste. When the content of the ceramic powder is 1% by mass or more and 20% by mass or less, it has excellent conductivity and dispersibility.

[0048] (Binder resin) The binder resin used in the conductive paste of this embodiment contains a polymer compound in which a cellulose-based compound and a polyvinyl acetal-based compound are bonded by a sulfur atom, and the molar ratio of the sulfur atoms contained in the polymer compound to the cellulose-based compound is 0.3 to 1.7, and the weight average molecular weight (Mw) of the polymer compound is 30,000 or more and less than 150,000.

[0049] That is, the binder resin used in the conductive paste of the present embodiment contains a polymer compound in which a cellulose-based compound and a polyvinyl acetal-based compound are bonded. Since the molecule of the polymer compound has a portion derived from the cellulose-based compound and a portion derived from the polyvinyl acetal-based compound, the dry film obtained from the conductive paste of the present embodiment can have surface smoothness due to the cellulose-based compound and adhesiveness to the green sheet due to the polyvinyl acetal-based compound. Furthermore, since the polymer compound has a structure of a cellulose-based compound and a polyvinyl acetal-based compound that are not compatible with each other in the same molecule, poor dispersion of the conductive paste can also be eliminated.

[0050] The weight average molecular weight (Mw) of the polymer compound used in the present invention is preferably 30,000 or more and less than 150,000, more preferably 60,000 or more and 130,000 or less, in terms of standard polystyrene conversion value by gel permeation chromatography (GPC).

[0051] If the weight average molecular weight of the polymer molecular compound is 30,000 or more, a desired viscosity can be obtained, and if it is less than 150,000, poor dispersion due to steric hindrance can be suppressed. Therefore, when the conductive paste is printed, the surface roughness of the dry film can be smoothed.

[0052] In addition, if the molecular weight of the polymer compound is small, the viscosity of the polymer compound tends to decrease. Therefore, the resin compounded in the conductive paste can be increased, and the adhesion can be improved. Also, when using conductive powder with a small particle size, it has the effect of suppressing an increase in the viscosity of the conductive paste.

[0053] The content of the polymer compound in which the cellulose-based compound and the polyvinyl acetal-based compound are bonded 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, based on 100 parts by mass of the conductive powder. When the content of the polymer compound is 1 part by mass or more based on 100 parts by mass of the conductive powder, the rheological properties by the cellulose compound and the adhesion effect by the polyvinyl acetal compound are exhibited, and the dispersibility is also excellent. Further, when the content of the polymer compound is more than 10 parts by mass, when the dry film of the conductive paste is sintered, carbon due to the polymer compound is gasified, resulting in delamination or a possible decrease in adhesion to the green sheet.

[0054] Since the molecule of the polymer compound of this embodiment includes a portion by the cellulose-based compound and a portion by the polyvinyl acetal-based compound, the dry film obtained from the conductive paste of this embodiment can have surface smoothness due to the cellulose-based compound and adhesiveness to the green sheet due to the polyvinyl acetal-based compound. Furthermore, since the polymer compound has a structure of a cellulose-based compound and a polyvinyl acetal-based compound that are not compatible with each other in the same molecule, it is possible to eliminate the poor dispersion of the conductive paste that occurs when the cellulose-based compound and the polyvinyl acetal-based compound are mixed and used.

[0055] Also, when the molar ratio of the sulfur atoms contained in the polymer compound to the cellulose-based compound is 0.3 to 1.7, that is, cellulose-based compound:sulfur atoms = 1.0:0.3 to 1.7, the surface roughness and dry film density of the dry film are more excellent than those of the conductive paste composed of the conventional binder resin using the cellulose-based compound and the polyvinyl acetal-based compound in combination. A more preferable range of the molar ratio is 0.5 to 1.5.

[0056] If the molar ratio of sulfur atoms contained in the polymer compound to the cellulose-based compound is 0.3 or more, unreacted cellulose-based compounds and polyvinyl acetal-based compounds will decrease, so that the effects as a polymer compound can be exhibited. Further, if the above molar ratio is 1.7 or less, the binding sites between the cellulose-based compound and the polyvinyl acetal-based compound in the polymer compound will not increase more than necessary, so that the deterioration of the fluidity of the conductive paste is suppressed, and the surface roughness of the dry film produced from the conductive paste becomes small.

[0057] The cellulose-based compound that can be used in this embodiment and the polymer compound in which the polyvinyl acetal-based compound is bonded will be described in more detail.

[0058] Both cellulose and polyvinyl acetal have hydroxyl groups in the molecule. In the cellulose-based compound, a functional group capable of reacting with other compounds to form a bond is introduced into the hydroxyl group of cellulose. On the other hand, in the polyvinyl acetal-based compound, a functional group capable of reacting with other compounds to form a bond and different from the functional group introduced into the cellulose-based compound is introduced into the hydroxyl group of polyvinyl acetal. That is, the reactive functional group introduced into the cellulose-based compound is different from the reactive functional group introduced into the polyvinyl acetal-based compound. Note that the functional group introduced into the cellulose-based compound and the functional group introduced into the polyvinyl acetal-based compound react, but it is difficult for the same functional groups to react. Here, it is difficult for the same functional groups to react in order to avoid the bonding of cellulose-based compounds to each other and polyvinyl acetal-based compounds to each other.

[0059] When the functional group introduced into the cellulose-based compound and the functional group introduced into the polyvinyl acetal-based compound are bonded, a polymer compound in which the cellulose-based compound and the polyvinyl acetal-based compound are bonded can be obtained. Specifically, when a thiol group is introduced into cellulose to form a cellulose-based compound and a vinyl group is introduced into a polyvinyl acetal resin to form a polyvinyl acetal-based compound, the thiol group and the vinyl group will bond, under the presence of a nucleophile or under conditions that generate radicals, the double bond of the vinyl group and the sulfur atom of the thiol group. As the polymer compound of the binder resin used in the conductive paste of the present embodiment, a polymer compound in which a cellulose-based compound and a polyvinyl acetal-based compound are bonded can be obtained by utilizing the bonding reaction between the thiol group and the vinyl group. Of course, a vinyl group may be introduced into the hydroxyl group of cellulose to form a cellulose-based compound, and a thiol group may be introduced into the hydroxyl group of the polyvinyl acetal resin to form a polyvinyl acetal-based compound.

[0060] That is, the cellulose-based compound may be a cellulose derivative having a thiol group or a vinyl group, and the polyvinyl acetal-based compound may be a polyvinyl acetal resin having a thiol group or a vinyl group. 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.

[0061] The cellulose-based compound of the polymer compound used as the binder resin of the conductive paste of the present embodiment is preferably a polymer compound obtained by bonding a compound to the hydroxyl group of cellulose, which is a natural polymer, and chemically modified. Here, the chemical modification is different from the chemical modification for introducing the functional group having the above-described reactivity, and is a chemical modification for alkyl etherification, esterification, etc.

[0062] Examples of the bonding of the compound with the hydroxyl group of cellulose include alkyl etherification and esterification. Examples of cellulose having a hydroxyl group include methyl cellulose, ethyl cellulose, propyl cellulose, butyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxybutyl methyl cellulose, cellulose acetate (acetyl cellulose, diacetyl cellulose, triacetyl cellulose, etc.), cellulose acetate propionate, cellulose acetate butyrate, nitrocellulose, and the like. Cellulose may be used alone or in combination of two or more thereof.

[0063] Since the conductive paste of the present embodiment contains an organic solvent, it is preferable that cellulose is also soluble in the organic solvent. From the viewpoints of solubility in the organic solvent and smoothness of the dry film of the conductive paste, it is more desirable to use ethyl cellulose as the cellulose.

[0064] The molecular weight of cellulose used as the polymer compound affects the viscosity of the conductive paste of the present embodiment. The weight average molecular weight (Mw) of cellulose is preferably 20,000 to 250,000, more preferably 50,000 to 220,000, in terms of standard polystyrene conversion value by GPC.

[0065] When the weight average molecular weight of cellulose is less than 20,000, the viscosity of the conductive paste becomes low, and when the weight average molecular weight of cellulose exceeds 250,000, the viscosity of the conductive paste may become too high. Further, the weight average molecular weight of the polymer compound can be controlled by the addition amount of the radical initiator when synthesizing the cellulose-based compound and the polyvinyl acetal-based compound. For example, when the amount of the radical initiator is increased, the bonds of the molecules of the cellulose-based compound and the polyvinyl acetal-based compound are broken, so that the molecular weight can be lowered. Therefore, the weight average molecular weight of the polymer compound may be controlled to a desired value depending on the weight average molecular weights of the cellulose-based compound and the polyvinyl acetal-based compound used and the addition amount of the radical initiator.

[0066] Not all of the hydroxyl groups of cellulose are chemically modified. In the case of cellulose before chemical modification, each cyclic structure of the glucose ring that constitutes cellulose has three hydroxyl groups, but in the case of cellulose after chemical modification, on average, 0.1 to 1 hydroxyl group per cyclic structure of the glucose ring that constitutes cellulose remains unmodified as a hydroxyl group. In the present invention, a reactive functional group is introduced into such unmodified hydroxyl groups.

[0067] On the other hand, polyvinyl acetal is usually a polymer composed of vinyl acetal / vinyl alcohol / vinyl acetate monomer units, and can be obtained by saponifying polyvinyl acetate to obtain polyvinyl alcohol and further acetalizing polyvinyl alcohol. Specifically, examples of polyvinyl acetal include those obtained by butyralizing polyvinyl alcohol (polyvinyl butyral), those obtained by formalizing polyvinyl alcohol (polyvinyl formal), and the like.

[0068] Polyvinyl acetal may be a commercially available product, and various polyvinyl acetals having different degrees of butyralization, degrees of formalization, amounts of acetyl groups, amounts of hydroxy groups, molecular weights, etc. are sold by Sekisui Chemical Co., Ltd., Kuraray Co., Ltd., and the like. Only one kind of polyvinyl acetal may be used, or two or more kinds may be used in combination.

[0069] Polyvinyl acetal is preferably soluble in an organic solvent. Due to its high solubility in organic solvents, polyvinyl butyral is more preferable as the polyvinyl acetal.

[0070] The polyvinyl acetal used as the high molecular compound affects the film strength and the viscosity of the solution depending on its molecular weight. Therefore, the weight average molecular weight of polyvinyl acetal is preferably in the range of 10,000 to 300,000, more preferably in the range of 20,000 to 250,000, in terms of standard polystyrene conversion value by GPC.

[0071] If the weight average molecular weight of polyvinyl acetal is less than 10,000, the solution viscosity becomes extremely low, making it difficult to adjust the viscosity of the inorganic particle-containing composition (paste or slurry). In addition, the strength and adhesion of the film formed by applying and drying the inorganic particle-containing composition may decrease. On the other hand, if the weight average molecular weight of polyvinyl acetal exceeds 300,000, the viscosity of the conductive paste becomes too high, deteriorating the dispersibility of the conductive powder. Further, the weight average molecular weight of the polymer compound can be controlled by the addition amount of the radical initiator when synthesizing the cellulose-based compound and the polyvinyl acetal-based compound. For example, increasing the amount of the radical initiator can break the molecular bonds of the cellulose-based compound and the polyvinyl acetal-based compound, thus lowering the molecular weight. Therefore, the weight average molecular weight of the polymer compound can be controlled to a desired value depending on the weight average molecular weight of the cellulose-based compound and the polyvinyl acetal-based compound used and the addition amount of the radical initiator.

[0072] Polyvinyl acetal has at least one hydroxyl group in one molecule. Generally, polyvinyl acetal has 20 to 40 mol% of hydroxyl groups as vinyl alcohol units constituting the polymer. A functional group with reactivity is introduced into this hydroxyl group for chemical modification.

[0073] As a compound that reacts with the hydroxyl group of cellulose for chemical modification, a compound having a thiol group or a vinyl group at one end and a carboxyl group at the other end can be used. The carboxyl group of the compound undergoes dehydration condensation with the hydroxyl group of the cellulose-based polymer compound to form an ester bond.

[0074] (Synthesis method of polymer compound) Hereinafter, an example of the synthesis method of the polymer compound used in this embodiment will be described. To obtain a cellulose-based compound or a polyvinyl acetal-based compound, an esterification or etherification may be performed between a compound having a functional group reactive with a hydroxyl group and another functional group reactive with other compounds, and the hydroxyl group of cellulose or the hydroxyl group of polyvinyl acetal. Examples of the functional group reactive with a hydroxyl group include a carboxyl group and a hydroxyl group.

[0075] The esterification reaction can be carried out, for example, using a condensing agent. Examples of the condensing agent include carbodiimide, diphenylphosphoric acid azide, 1-hydroxybenzotriazole, etc. Only one kind of condensing agent may be used, or two or more kinds may be used in combination. Among them, carbodiimide is preferable because it has excellent versatility and reactivity and can cause the reaction to proceed under low-temperature conditions without being affected by moisture in the reaction environment.

[0076] Examples of carbodiimide include dicyclohexylcarbodiimide, diisopropylcarbodiimide, N-[3-(dimethylamino)propyl]-N'-ethylcarbodiimide, N-[3-(dimethylamino)propyl]-N'-ethylcarbodiimide methiodide, etc. Among them, from the viewpoint of availability, dicyclohexylcarbodiimide and diisopropylcarbodiimide are preferable. Also, when using carbodiimide, it is also preferable to use a base such as dimethylaminopyridine or triethylamine as a reaction accelerator in the range of 0.01 mol% to 10 mol% with respect to carbodiimide.

[0077] On the other hand, the etherification reaction can be efficiently carried out by using hydroxides of alkali metals such as KOH and NaOH, and alkali metal hydrides such as NaH and KH as reaction catalysts.

[0078] To obtain a cellulose-based compound, cellulose is dissolved in an aprotic solvent such as ethyl acetate, and a compound having a vinyl group or a thiol group, which is a carboxy group that forms an ester bond with a hydroxyl group and a functional group that reacts with another compound, is mixed, and a condensing agent and a base such as dimethylaminopyridine, which is a nucleophile for promoting the esterification reaction, are used in combination in the range of 0.01 mol% to 10 mol%.

[0079] The molar ratio of sulfur atoms in the polymer compound used in this embodiment to the cellulose-based compound is 0.3 to 1.7. Therefore, 0.3 to 1.7 mol of a compound having a functional group that reacts with another compound needs to be added per 1 mol of cellulose.

[0080] The reaction temperature for synthesizing the cellulose-based compound is preferably in the range from room temperature to 50°C. In the system where the synthesis reaction of the cellulose-based compound is completed, there are mixed unreacted cellulose in which a hydroxyl group is not introduced with a functional group having reactivity with other compounds, a cellulose-based compound in which one reactive functional group is introduced, and a cellulose-based compound in which a plurality of reactive functional groups are introduced. Chemical modification is a matter of probability, and the cellulose-based compound in which one hydroxyl group of cellulose is chemically modified is the most abundant. In the present invention, a mixture of these unreacted cellulose, cellulose into which a plurality of functional groups are introduced, and cellulose into which one reactive functional group is introduced is used as the cellulose-based compound. Then, after the synthesis of the cellulose-based compound is completed, the solvent may be removed by distillation.

[0081] To synthesize a polyvinyl acetal-based compound, polyvinyl acetal is dissolved in an aprotic solvent such as ethyl acetate, and a compound having a vinyl group or a thiol group, which is a functional group that reacts with a carboxy group that forms an ester bond with a hydroxyl group and other compounds, is mixed, and a condensing agent and a base such as dimethylaminopyridine, which is a nucleophile for promoting the esterification reaction, are preferably used in combination in the range of 0.01 mol% to 10 mol%.

[0082] The reaction temperature for the chemical modification of the hydroxyl group of polyvinyl acetal is preferably in the range from room temperature to 50°C. Note that a functional group of a thiol group or a vinyl group is introduced into polyvinyl acetal, but not all of the polyvinyl acetal has the functional group introduced, and unreacted polyvinyl acetal is mixed. In the present invention, a mixture of these unreacted polyvinyl acetal and polyvinyl acetal into which a functional group is introduced is used as the polyvinyl acetal-based compound. Then, after the synthesis of the polyvinyl acetal-based compound is completed, the solvent may be removed by distillation.

[0083] The polymer compound used in this embodiment is synthesized by dissolving a cellulose-based compound and a polyvinyl acetal-based compound in an organic solvent, adding a radical initiator, and heating. By reacting the vinyl group in either the cellulose-based compound or the polyvinyl acetal-based compound with the thiol group in the other, the cellulose-based compound and the polyvinyl acetal-based compound are bonded together.

[0084] Examples of the radical initiator include azo compounds such as 2,2'-azobisisobutyronitrile (AIBN), 3-carboxypropionitrile, azobismaleonitrile, dimethyl-(2,2')-azobis(2-methylpropionate); organic peroxides such as benzoyl peroxide, lauroyl peroxide, potassium persulfate; a mixture of 1-hydroxy-cyclohexyl-phenyl-ketone and benzophenone with a mass ratio of 1:1; alkylphenone-based compounds such as 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-(4-(2-(2-hydroxyethoxy)ethoxy)phenyl)-2-methylpropan-1-one.

[0085] Alternatively, the polymer compound may be synthesized by dissolving the cellulose-based compound and the polyvinyl acetal-based compound in a solvent, adding a nucleophile such as a base like amine, and heating to bond the cellulose-based compound and the polyvinyl acetal-based compound.

[0086] In this case, the reaction temperature for bonding the cellulose-based compound and the polyvinyl acetal-based compound can be appropriately selected, but a temperature of 60°C or higher is desirable.

[0087] As the solvent, dihydroterpinyl acetate, isobornyl acetate, isobornyl propionate, isobornyl butyrate, isobornyl isobutyrate, acetate solvents such as ethylene glycol monobutyl ether acetate, dipropylene glycol methyl ether acetate, butyl carbitol acetate, terpene solvents such as terpineol and dihydroterpineol, which are solvents that can be used in the conductive paste, can be used. If the solvent used for the conductive paste is used as the solvent, the dissolved product of the polymer compound obtained after synthesis can be directly used as the vehicle, which is the raw material used for the conductive paste.

[0088] In this embodiment, in addition to the polymer compound in which the cellulose-based compound and the polyvinyl acetal-based compound are bonded, cellulose-based resins such as methyl cellulose, ethyl cellulose, ethyl hydroxyethyl cellulose, and nitrocellulose, acrylic resins, and polyvinyl acetal-based resins such as polyvinyl butyral resin can also be added. One or more of the above resins may be used. In particular, in the present invention, it is preferable to use ethyl cellulose or polyvinyl butyral used in the polymer compound. The molecular weight of the resin that can be added in this way is 10,000 or more and 250,000 or less, which is equivalent to that of the polymer compound by GPC, and more preferably 30,000 or more and 200,000 or less.

[0089] Generally, cellulose-based resins and polyvinyl acetal-based resins are not compatible. However, the polymer compound can assist in the compatibilization of the cellulose-based resin and the polyvinyl acetal-based resin and suppress the phase separation of the cellulose-based resin and the polyvinyl acetal-based resin. In addition, since the polymer compound can assist in the compatibilization of the cellulose-based resin and the polyvinyl acetal-based resin, even if a solvent that dissolves the cellulose-based resin more easily than the polyvinyl acetal-based resin is used as the conductive paste, the polymer compound coexists with the polyvinyl acetal-based resin, showing the effect of dissolving the polyvinyl acetal-based resin. These effects are due to the fact that the molecule of the polymer compound has a skeleton of a cellulose-based compound and a skeleton of a polyacetal-based compound.

[0090] In the conductive paste of this embodiment, the proportion of the polymer compound with respect to the total mass of the cellulose-based resin, polyvinyl acetal-based resin, and the polymer compound among the binder resins is 20% by mass or more, and preferably 30% by mass or more. When the proportion of the polymer compound with respect to the total mass of the cellulose-based resin, polyvinyl acetal-based resin, and the polymer compound is less than 20% by mass, the suppression of phase separation remains at a part of the conductive paste and may not result in satisfactory results. Note that the proportion of the polymer compound with respect to the total mass of the cellulose-based resin, polyvinyl acetal-based resin, and the polymer compound among the binder resins can be 99% by mass or less, or 95% by mass or less.

[0091] When such phase separation occurs, there is uneven distribution of the binder resin, conductive powder, or ceramic powder in the dry film obtained by printing (coating) and drying the conductive paste, and voids where no conductive material exists may occur in the internal electrode obtained by firing the dry film due to the uneven distribution of the binder resin or ceramic powder. When such voids occur in the internal electrode, the area of the internal electrode becomes narrow, leading to a decrease in the capacitance of the MLCC. The effect of the polymer compound in suppressing the phase separation between the cellulose resin and the polyvinyl acetal resin contributes to the uniformization of the particle distribution in the dry film. As a result, the film breakage phenomenon of the electrode layer after firing is solved and the capacitance of the MLCC increases.

[0092] The content of the binder resin 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, based on the total amount of the conductive paste. When the content of the binder resin is 0.5% by mass or more and 10% by mass or less, it has excellent conductivity and dispersibility.

[0093] For example, the cellulose derivative may be ethyl cellulose having a thiol group or a vinyl group, and the polyvinyl acetal resin may be polyvinyl butyral having a thiol group or a vinyl group.

[0094] Specifically, the cellulose-based compound may be a first esterification reactant obtained by dehydration condensation of the carboxy group of a carboxylic acid having a thiol group or a vinyl group and the hydroxyl group of cellulose, and the polyvinyl acetal-based compound may be a second esterification reactant obtained by dehydration condensation of the carboxy group of a carboxylic acid having a thiol group or a vinyl group and the hydroxyl group of polyvinyl acetal. When the first esterification reactant has a thiol group, the second esterification reactant has a vinyl group, and when the first esterification reactant has a vinyl group, the second esterification reactant has a thiol group. The polymer compound may be a thiol-ene reactant of the first esterification reactant and the second esterification reactant.

[0095] More specifically, the first esterification reactant may be an esterification reactant obtained by dehydration condensation of the carboxy group of 3-allyloxypropionic acid and the hydroxyl group of ethyl cellulose, and the second esterification reactant may be an esterification reactant obtained by dehydration condensation of the carboxy group of 3-mercaptopropionic acid and the hydroxyl group of polyvinyl butyral.

[0096] (Organic solvent) The organic solvent is not particularly limited, and a known organic solvent capable of dissolving the above binder resin can be used. Examples of the organic solvent include acetate solvents such as dihydroterpinyl acetate, isobornyl acetate, isobornyl propionate, isobornyl butyrate, isobornyl isobutyrate, ethylene glycol monomethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, dipropylene glycol methyl ether acetate, and butyl carbitol acetate; terpene solvents such as terpineol and dihydroterpineol; hydrocarbon solvents such as tridecane, nonane, and cyclohexane; and petroleum-based hydrocarbon solvents such as mineral spirit. The organic solvent may be used alone or in combination of two or more. In addition, the compatibility with the ceramic green sheet can also be considered in the selection of the solvent.

[0097] The content of the organic solvent is preferably 40 parts by mass or more and 100 parts by mass or less, more preferably 65 parts by mass or more and 95 parts by mass or less with respect to 100 parts by mass of the conductive powder. When the content of the organic solvent is 40 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the conductive powder, the conductivity and dispersibility are excellent.

[0098] The content of the organic solvent 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 with respect to the total amount of the conductive paste. When the content of the organic solvent is 20% by mass or more and 60% by mass or less with respect to the total amount of the conductive paste, the conductivity and dispersibility are excellent.

[0099] (Dispersant) The conductive paste of the present embodiment can contain a dispersant. The role of the dispersant is to adsorb on the surface of the inorganic powder (conductive powder and ceramic powder) to suppress the aggregation of the inorganic powders, or to improve the wettability with the organic vehicle and disperse it in the conductive paste. The dispersant (surfactant) may include an acid-based dispersant containing a higher fatty acid, a polymer surfactant, etc., a cationic dispersant other than the acid-based dispersant, a nonionic dispersant, an amphoteric surfactant, and a polymer-based dispersant.

[0100] Also, only one type or a plurality of types of dispersants may be selected, and the content of the dispersant in the conductive paste can be appropriately selected in consideration of the viscosity, adhesiveness, long-term storage stability, etc. of the conductive paste, and may be included as long as the effects of the present invention are not inhibited.

[0101] Also, the mass average molecular weight of the dispersant is preferably from 200 to 100,000, more preferably from 300 to 30,000. If the mass average molecular weight is less than 200, sufficient electrostatic repulsive force may not be obtained for the particles, and the dispersibility and storage stability of the particles may decrease. Usually, the dispersant adsorbs on the particle surface to form an adsorption layer of the dispersant, and by imparting electrostatic repulsive force and steric repulsive force to the particles, a paste with excellent dispersibility can be obtained. However, it is considered that as time passes, due to the collision of particles with each other, the particles aggregate with each other, overcoming the repulsive force of the adsorption layer. Therefore, the mass average molecular weight is preferably 200 or more. Also, if the mass average molecular weight is greater than 100,000, the compatibility with the organic vehicle and the organic solvent may decrease, aggregation of particles may occur, and the dispersibility and storage stability may decrease. In addition, there also arises a problem that the viscosity of the conductive paste increases.

[0102] The addition amount of the dispersant, as the addition amount with respect to the conductive metal powder, is preferably from 0.01 to 5.00 parts by mass, more preferably from 0.20 to 2.00 parts by mass with respect to 100 parts by mass of the conductive metal powder content. If the dispersant is less than 0.01 part 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 property deteriorates, and problems such as a decrease in the dry film density occur.

[0103] The polymer dispersant is anionic and preferably has a carboxy group or a carboxylic anhydride group. By using an anionic polymer dispersant, the dispersibility of inorganic powders such as conductive powders and ceramic powders in the organic vehicle can be further improved. Here, the carboxylic anhydride group refers to a state in which H2O is dehydrated and anhydrified from two carboxy groups. Examples include acid anhydrides such as phthalic anhydride and maleic anhydride, and are units of molecules composed of a state in which two carboxy groups are dehydrated.

[0104] The anionic polymer dispersant preferably has a graft chain. The graft chain can also be expected to improve the solubility in various organic solvents.

[0105] The mass average molecular weight of the anionic polymer dispersant is desirably 1,000 or more and 100,000 or less, more desirably 5,000 or more and 70,000 or less, and even more desirably 10,000 or more and 60,000 or less. By setting the mass average molecular weight of the polymer dispersant to 1,000 or more, the dispersibility of the inorganic powder in the organic vehicle can be improved. If the mass average molecular weight is greater than 100,000, the compatibility with the organic vehicle and the organic solvent may decrease, aggregation of particles such as conductive powder and ceramic powder may occur, and the dispersibility and storage stability may decrease.

[0106] Such a polymer dispersant has a carboxy group or a carboxylic anhydride group in the functional group of the main chain. As the anionic polymer dispersant, it is desirable that the graft chain further has an oxyethylene group from the viewpoint of adsorption to the inorganic powder.

[0107] The anionic polymer dispersant can include one or more types. That is, from the length of the main chain, the length of the graft chain, the presence or absence of the graft chain, etc., a plurality of types of polymer dispersants can be included. The content of the anionic polymer dispersant in the conductive paste can be appropriately selected in consideration of the viscosity, stickiness, long-term storage stability, etc. of the conductive paste, and may be included as long as the effects of the present invention are not inhibited.

[0108] Furthermore, the conductive paste of the present embodiment can include a dispersant in addition to the anionic polymer dispersant. For example, as the dispersant (surfactant), it may include acid-based dispersants such as higher fatty acids, phosphoric acid, and polymer surfactants, cationic dispersants other than acid-based dispersants, nonionic dispersants, amphoteric surfactants, and polymer-based dispersants.

[0109] Also, the content of the dispersant in the conductive paste can be appropriately selected in consideration of the viscosity, stickiness, long-term storage stability, etc. of the conductive paste, and may be included as long as the effects of the present invention are not inhibited.

[0110] Also, for both anionic polymer dispersants and other dispersants, the mass average molecular weight of the dispersant is preferably from 200 to 100,000, more preferably from 300 to 30,000. When the mass average molecular weight is less than 200, the dispersibility of the particles and the storage stability may decrease. Usually, the dispersant adsorbs on the particle surface to form an adsorption layer of the dispersant, and by imparting an electrostatic repulsive force or a steric repulsive force to the particles, a paste with excellent dispersibility can be obtained. However, as time passes, due to the collision of particles with each other, it is considered that the cohesive force of the particles overcomes the repulsive force of the adsorption layer and the particles aggregate with each other, so the mass average molecular weight is preferably 200 or more. Also, when the mass average molecular weight is greater than 100,000, the compatibility with the organic vehicle and the organic solvent may decrease, aggregation of the particles may be caused, and a decrease in dispersibility and storage stability may occur. Also, a problem of increased paste viscosity occurs.

[0111] The total addition amount of the anionic polymer dispersant and other dispersants, as the addition amount to the conductive metal powder, is preferably from 0.01 to 5.00 parts by mass, more preferably from 0.20 to 2.00 parts by mass with respect to 100 parts by mass of the conductive metal powder content. When the dispersant is less than 0.01 part by mass, it tends to be difficult to obtain sufficient dispersibility. On the other hand, when it exceeds 5.00 parts by mass, the drying property deteriorates, and problems such as a decrease in the dry film density occur.

[0112] (Other additives) In order to impart flexibility to the printed electrode layer, additives such as plasticizers can be used as necessary for the conductive paste.

[0113] (Manufacturing method of conductive paste) The manufacturing method of the conductive paste of this embodiment is not particularly limited, and conventionally known methods can be used. The conductive paste can be manufactured, for example, by preparing each of the above components and stirring and kneading them with a three-roll mill, ball mill, mixer, or the like. At that time, if a dispersant is applied to the surface of the conductive powder in advance, the conductive powder is sufficiently dispersed without agglomeration, and the dispersant spreads over the surface, making it easy to obtain a uniform conductive paste. Also, a binder resin can be dissolved in an organic solvent for the vehicle to prepare an organic vehicle, and the conductive powder, ceramic powder, organic vehicle, and dispersant can be added to the organic solvent for the paste, followed by stirring and kneading with a mixer to prepare a conductive paste.

[0114] Further, as the organic solvent for the vehicle, it is preferable to use the same one as the organic solvent for the paste that adjusts the viscosity of the conductive paste in order to improve the compatibility of the organic vehicle. The content of the organic solvent for the vehicle is, for example, 5 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the conductive powder. Also, the content of the organic solvent for the vehicle is preferably 10% by mass or more and 40% by mass or less with respect to the total amount of the conductive paste.

[0115] The surface smoothness of the dry film formed by printing the conductive paste can be evaluated by surface roughness. The surface roughness of the conductive paste can be measured, for example, by the method described in the examples (a method of measuring the arithmetic mean height Sa based on the ISO 25178 standard using OLS-5000 manufactured by Evident Corporation). When the surface smoothness of the dry film is evaluated by the arithmetic mean height Sa, the value is preferably 55 nm or less. If the arithmetic mean height Sa is 55 nm or less, even if the dielectric layer is thinned (for example, 1.0 μm or less), it is possible to suppress the concentration of the electric field at the convex portions of the electrode layer due to the unevenness of the internal electrode layer and the resulting decrease in the insulation resistance of the dielectric layer.

[0116] Moreover, considering the manufacturing process of the multilayer ceramic capacitor, if the surface roughness of the dried film of the conductive paste is low, the dried film of the conductive paste adheres tightly to the green sheet as a surface, so the adhesion between the dried film of the conductive paste and the green sheet is excellent. Therefore, it is desirable that the surface roughness of the dried film of the conductive paste be lower.

[0117] [Electronic component, multilayer ceramic capacitor] The conductive paste of the present invention can be suitably used for electronic components such as multilayer ceramic capacitors. A multilayer ceramic capacitor has a dielectric layer formed using a green sheet and an internal electrode layer formed using a conductive paste.

[0118] It is preferable that the dielectric ceramic powder contained in the green sheet and the ceramic powder contained in the conductive paste are powders of the same composition. For example, barium titanate can be used. In the multilayer ceramic capacitor manufactured using the conductive paste of this embodiment, even when the thickness of the green sheet is, for example, 3 μm or less, sheet attack and peeling failure of the green sheet are suppressed.

[0119] Hereinafter, embodiments of the electronic component and the like of the present invention will be described with reference to the drawings. In the drawings, it may be expressed schematically or the scale may be changed as appropriate. Also, the position, direction, etc. of the members will be described with reference to the XYZ orthogonal coordinate system shown in FIG. 1 and the like as appropriate. In this XYZ orthogonal coordinate system, the X direction and the Y direction are horizontal directions, and the Z direction is the vertical direction (up and down direction).

[0120] FIGS. 1A and 1B are a perspective view and a side cross-sectional view showing 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 laminate 10 in which a dielectric layer 12 and an internal electrode layer 11 are alternately laminated, and an external electrode 20.

[0121] The manufacturing method of the multilayer ceramic capacitor 1 using the above conductive paste will be described below. First, the conductive paste is printed on a dielectric layer made of a green sheet, dried, and a dry film is formed. A plurality of dielectric layers having this dry film on their upper surfaces are laminated and pressure-bonded to obtain a laminate. Then, the laminate is fired and integrated to produce a ceramic laminate 10 in which the internal electrode layers 11 and the dielectric layers 12 are alternately laminated. Thereafter, a pair of external electrodes 20 are formed at both ends of the ceramic laminate 10, thereby manufacturing the multilayer ceramic capacitor 1. This will be described in more detail below.

[0122] First, a green sheet, which is an unfired ceramic sheet using a dielectric material, is prepared. Examples of this green sheet include a paste for a dielectric layer obtained by adding an organic binder such as polyvinyl butyral and a solvent such as terpineol to a raw material powder of a predetermined ceramic such as barium titanate, and applying the paste in a sheet shape on a support film such as a PET film and drying to remove the solvent. The thickness of the dielectric layer made of the green sheet is not particularly limited, but from the viewpoint of the demand for miniaturization of the multilayer ceramic capacitor, it is preferably 0.05 μm or more and 3 μm or less.

[0123] Next, a plurality of the above conductive pastes are printed (applied) on one side of this green sheet by a known method such as the screen printing method, dried, and dry films are formed. Note that, from the viewpoint of the demand for thinning of the internal electrode layer 11, the thickness of the conductive paste (dry film) after printing is preferably set to a thickness such that the thickness of the dry film after drying is 1 μm or less.

[0124] Next, the green sheet is peeled from the support film, and the dielectric layers made of the green sheet and the dry films formed on one side thereof are laminated so as to be alternately arranged, and then a laminate is obtained by heating and pressing. Note that a configuration in which protective green sheets on which the conductive paste is not applied are further arranged on both surfaces of the laminate may also be adopted.

[0125] Next, after cutting the laminate into a predetermined size to form a green chip, the green chip is subjected to a debinding process and fired in a reducing atmosphere to produce the ceramic laminate 10. In the debinding process, the atmosphere is preferably air or an N2 gas atmosphere. The temperature during the debinding process is, for example, 200°C or higher and 400°C or lower. Also, the holding time of the above temperature during the debinding process is preferably 0.5 hours or more and 24 hours or less. Further, firing is performed in a reducing atmosphere to suppress oxidation of the metal used for the internal electrode layer, and the temperature during firing of the laminate is, for example, 1000°C or higher and 1350°C or lower, and the holding time of the temperature during firing is, for example, 0.5 hours or more and 8 hours or less.

[0126] By firing the green chip, the organic binder in the green sheet is completely removed, and the ceramic raw material powder is fired to form the ceramic dielectric layer 12. Also, the organic vehicle in the dry film is removed, and the nickel powder or the alloy powder mainly composed of nickel is sintered, melted, and integrated to form the internal electrode layer 11, whereby a multilayer ceramic fired body in which a plurality of dielectric layers 12 and internal electrode layers 11 are alternately laminated is formed. Note that, from the viewpoint of taking in oxygen into the interior of the dielectric layer to improve reliability and suppressing reoxidation of the internal electrode, an annealing process may be performed on the multilayer ceramic fired body after firing.

[0127] Then, a pair of external electrodes 20 are provided on the produced multilayer ceramic fired body to manufacture the multilayer ceramic capacitor 1. For example, the external electrode 20 includes an external electrode layer 21 and a plating layer 22. The external electrode layer 21 is electrically connected to the internal electrode layer 11. Note that, as the material of the external electrode 20, for example, copper, nickel, or an alloy thereof can be preferably used. Note that the electronic component is not limited to the multilayer ceramic capacitor, and may be an electronic component other than the multilayer ceramic capacitor such as a varistor.

Example

[0128] Hereinafter, the present invention will be described in detail based on examples and comparative examples, but the present invention is not limited by the examples at all.

[0129] The materials used in the examples and comparative examples of the present invention are shown in Table 1.

[0130]

Table 1

[0131] [Polymer compound] The polymer compound was synthesized as follows: First, a cellulose-based compound and a polyvinyl acetal-based compound were synthesized, and then these were further reacted and synthesized.

[0132] 〈Synthesis of cellulose-based compound〉 (Synthesis of cellulose-based compound (1a) having a vinyl group) Ethyl cellulose (manufactured by Dow Chemical, "Ethocel STD-10", number average molecular weight Mn (standard polystyrene conversion value by GPC): 22,700, average number of unetherified hydroxyl groups among the hydroxyl groups having one cyclic structure of the glucose ring: 0.48) was prepared and dried under reduced pressure to evaporate moisture.

[0133] 100 parts by mass of the dried ethyl cellulose was dissolved in 900 parts by mass of ethyl acetate to obtain a solution. To the obtained solution, 0.50 part by mass of 3-allyloxypropionic acid corresponding to the introduction amount of an average of 1 vinyl group per molecule of ethyl cellulose, 0.56 part by mass of diisopropylcarbodiimide as a condensing agent, and 0.011 part by mass of dimethylaminopyridine as a reaction accelerator were added, and the reaction was carried out by stirring at 40 ° C for 5 hours. Then, by removing ethyl acetate, a cellulose-based compound (1a) in which a vinyl group was introduced into ethyl cellulose was obtained as a solid.

[0134] When a part of the obtained solid was analyzed by FT-IR and 1H-NMR, the formation of an ester bond was confirmed, and it was also confirmed that a vinyl group in the same molar amount as the charged 3-allyloxypropionic acid was introduced into ethyl cellulose.

[0135] In addition, as described above, in the obtained cellulose-based compound (1a), in addition to the compound in which a vinyl group is introduced into ethyl cellulose, unreacted ethyl cellulose is mixed, and the mixture including this is defined as the cellulose-based compound (1a). The same applies to the ethyl cellulose-based compounds (1c), (1e) to (1i) appearing below.

[0136] Table 2 shows the numbers of the synthesized cellulose-based compounds, the types of cellulose used in the synthesis, the weight average molecular weight, the number average molecular weight, the types of functional groups introduced into cellulose, the number of functional group introductions (on average, how many functional groups (vinyl group or thiol group) are introduced per molecule of ethyl cellulose), the average number of hydroxyl groups (among the hydroxyl groups possessed by one cyclic structure of the glucose ring, the average number of hydroxyl groups not etherified), the vinyl group (the amount of 3-allyloxypropionic acid used), the thiol group (the amount of 3-mercaptopropionic acid used), the amount of condensing agent used, and the amount of reaction accelerator used. The same applies to the ethyl cellulose-based compounds (1b) to (1i) appearing below, which are also shown in Table 2.

[0137]

Table 2

[0138] (Synthesis of Cellulose-Based Compounds (1c, 1e to 1i) Having Vinyl Groups) The types of each material used in the synthesis of the cellulose-based compound and the blending amounts of each material were changed from the conditions for synthesizing the cellulose-based compound (1a) as described in Table 2. Otherwise, the cellulose-based compounds (1c), (1e) to (1i) having a vinyl group were synthesized based on the same conditions as those for the cellulose-based compound (1a).

[0139] (Synthesis of Cellulose-based Compound (1b) with Thiol Group) Ethyl cellulose (manufactured by Dow Chemical, "Ethocel STD-10", number average molecular weight Mn (standard polystyrene conversion value by GPC): 22,700, average number of unetherified hydroxyl groups among the hydroxyl groups in one cyclic structure of the glucose ring: 0.48) was prepared and dried under reduced pressure to evaporate moisture.

[0140] 100 parts by mass of the dried ethyl cellulose was dissolved in 900 parts by mass of ethyl acetate to obtain a solution. To the obtained solution, 0.48 parts by mass of 3-mercaptopropionic acid corresponding to the introduction amount of an average of 1 thiol group per molecule of ethyl cellulose, 0.58 parts by mass of diisopropylcarbodiimide as a condensing agent, and 0.015 parts by mass of dimethylaminopyridine as a reaction accelerator were added, and the mixture was stirred at 40 °C for 5 hours to carry out the reaction. Then, by removing ethyl acetate, a cellulose-based compound (1b) in which a thiol group was introduced into ethyl cellulose was obtained as a solid.

[0141] When a part of the obtained solid was analyzed by FT-IR and 1H-NMR, the formation of an ester bond was confirmed, and it was confirmed that a thiol group in the same molar amount as the charged 3-mercaptopropionic acid was introduced into ethyl cellulose.

[0142] In addition, in the cellulose-based compound (1b) obtained by the synthesis method as described above, in addition to the compound in which a thiol group was introduced into ethyl cellulose, unreacted ethyl cellulose was mixed, and the mixture including this was regarded as the cellulose-based compound (1b). The same applies to the ethyl cellulose-based compound (1d) appearing below.

[0143] (Synthesis of Cellulose-based Compound (1d) with Thiol Group) As shown in Table 2, the types of each material used in the synthesis of the cellulose-based compound and the blending amounts of each material were changed from those of the cellulose-based compound (1b). Otherwise, the synthesis of the cellulose-based compound (1d) having a thiol group was carried out under the same conditions as those of the cellulose-based compound (1b).

[0144] <Synthesis of Polyvinyl Acetal Compounds> (Synthesis of Polyvinyl Butyral Compounds (2a) Having Thiol Groups) Polyvinyl butyral (“BL-S” manufactured by Sekisui Chemical Co., Ltd., number average molecular weight Mn (standard polystyrene conversion value by GPC): 23,000, hydroxy group content: about 22 mol%) was prepared and dried under reduced pressure to evaporate water.

[0145] 100 parts by mass of the dried polyvinyl butyral was dissolved in 900 parts by mass of ethyl acetate. To the resulting solution, 0.48 part by mass of 3-mercaptopropionic acid corresponding to the introduction amount of an average of 1 thiol group per molecule of polyvinyl butyral, 0.57 part by mass of diisopropylcarbodiimide as a condensing agent, and 0.014 part by mass of dimethylaminopyridine as a reaction accelerator were added, and the mixture was stirred at 40 ° C for 5 hours to carry out the reaction. Then, by removing ethyl acetate, a polyvinyl butyral-based compound (2a) in which a thiol group was introduced into polyvinyl butyral was obtained as a solid.

[0146] When a part of the obtained solid was analyzed by FT-IR and 1H-NMR, the formation of an ester bond was confirmed, and it was confirmed that a thiol group in the same molar amount as the charged 3-mercaptopropionic acid was introduced into polyvinyl butyral.

[0147] In addition, in the polyvinyl butyral-based compound (2a), in addition to the compound in which a thiol group is introduced into polyvinyl butyral, unreacted polyvinyl butyral is mixed, and the mixture including this is referred to as the polyvinyl butyral-based compound (2a). The same applies to the polyvinyl butyral-based compounds (2c), (2e) to (2h) appearing below.

[0148] Table 3 shows the numbers of the synthesized butyral compounds, the types of polyvinyl butyral used in the synthesis, the weight-average molecular weight, the number-average molecular weight, the types of functional groups introduced into the polyvinyl butyral, the number of functional groups introduced (on average, how many functional groups (vinyl groups or thiol groups) are introduced per molecule of polyvinyl butyral), the amount of hydroxy groups, the vinyl groups (the amount of 3-allyloxypropionic acid used), the thiol groups (the amount of 3-mercaptopropionic acid used), the amount of condensing agent used, and the amount of reaction accelerator used. The same applies to the polyvinyl butyral compounds (2b) to (2h) that appear below, which are also shown in Table 3.

[0149] [Table 3]

[0150] (Synthesis of polyvinyl butyral compounds (2c, 2e to 2h) having thiol groups) The types of each material used in the synthesis of the polyvinyl butyral compound and the blending amount of each material were changed from the conditions for synthesizing the polyvinyl butyral compound (2a) as described in Table 2. Otherwise, the polyvinyl butyral compounds (2c), (2e) to (2h) having thiol groups were synthesized based on the same conditions as those for the polyvinyl butyral compound (2a).

[0151] (Synthesis of polyvinyl butyral compound (2b) having vinyl groups) Polyvinyl butyral (''BL-S'' manufactured by Sekisui Chemical Co., Ltd., number-average molecular weight Mn (standard polystyrene conversion value by GPC): 23,000, amount of hydroxy groups: about 22 mol%) was prepared and dried under reduced pressure to evaporate moisture.

[0152] 100 parts by mass of the dried polyvinyl butyral was dissolved in 900 parts by mass of ethyl acetate to obtain a solution. To the obtained solution, 0.50 part by mass of 3-allyloxypropionic acid corresponding to the introduction amount of an average of 1 vinyl group per molecule of polyvinyl butyral, 0.55 part by mass of diisopropylcarbodiimide as a condensing agent, and 0.011 part by mass of dimethylaminopyridine as a reaction accelerator were added, and the mixture was stirred at 40 ° C for 5 hours to carry out the reaction. Thereafter, by removing ethyl acetate, a polyvinyl butyral-based compound (2b) having a vinyl group introduced into polyvinyl butyral was obtained as a solid.

[0153] When a part of the obtained solid was analyzed by FT-IR and 1H-NMR, formation of an ester bond was confirmed, and it was confirmed that a vinyl group in the same molar amount as the charged 3-allyloxypropionic acid was introduced into polyvinyl butyral.

[0154] In addition, in the polyvinyl butyral-based compound (2b) obtained by the synthesis method as described above, in addition to the compound in which a vinyl group is introduced into polyvinyl butyral, unreacted polyvinyl butyral is mixed, and the mixture including this is defined as the polyvinyl butyral-based compound (2b). The same applies to the polyvinyl butyral-based compound (2d) appearing below.

[0155] (Synthesis of polyvinyl butyral-based compound (2d) having a vinyl group) The types of each material used for the synthesis of the polyvinyl butyral-based compound and the blending amount of each material were changed from those of the polyvinyl butyral-based compound (2b) as shown in Table 3. Otherwise, the polyvinyl butyral-based compound (2d) having a vinyl group was synthesized under the same conditions as those of the polyvinyl butyral-based compound (2b).

[0156] [Synthesis of polymer compound] (Synthesis of polymer compound aa) When the total of the cellulose-based compound, the polyvinyl butyral-based compound, and the organic solvent was 100 parts by mass, 7.21 parts by mass of the cellulose-based compound (1a) and 6.27 parts by mass of the polyvinyl butyral-based compound (2b) were dissolved in 86.52 parts by mass of the solvent dihydroterpineol. This solution was transferred to a glass flask reaction vessel, and after nitrogen substitution, 0.14 parts by mass of azobisisobutyronitrile as a radical initiator was added to the solution, and the reaction was carried out at 80 °C for 3 hours while stirring to obtain an organic vehicle aa containing the polymer compound aa and dihydroterpineol. Here, the cellulose-based compound (1a) and the polyvinyl butyral-based compound (2a) have the same number of moles, and since an average of 1 thiol group was introduced per molecule of polyvinyl butyral as described above, the molar ratio of the sulfur atom contained in the polymer compound aa to the cellulose-based compound (1a) is 1. The organic vehicle aa contains about 13.5 parts by mass of the polymer compound aa (total amount of 7.21 parts by mass of the cellulose-based compound (1a) and 6.27 parts by mass of the polyvinyl butyral-based compound (2b)).

[0157] Here, the polymer compound aa is a mixture of the polymer compound in which the cellulose-based compound (1a) and the polyvinyl butyral-based compound (2a) are bonded, unreacted ethyl cellulose, and unreacted polyvinyl butyral. In the examples, this mixture is regarded as the polymer compound aa.

[0158] In addition, when the produced polymer compound 1 was analyzed by FT-IR and 1H-NMR, an -S- bond was confirmed, and the target structure was obtained. Furthermore, the weight average molecular weight (Mw: standard polystyrene conversion value by GPC) of the polymer compound aa was measured.

[0159] Table 4 shows the numbers of the organic vehicles containing the synthesized polymer compounds, the numbers and amounts used (parts by mass) of the cellulose-based compounds (EC-based compounds) used in the synthesis, the numbers and amounts used (parts by mass) of the polyvinyl butyral-based compounds (PVB-based compounds) used in the synthesis, the amount used (parts by mass) of dihydroterpineol as the organic solvent, the amount used (parts by mass) of azobisisobutyronitrile as the radical initiator, and the weight-average molecular weight of the polymer compound obtained by measurement. The polymer compounds bb to ih, cc', and dd' that appear below are also shown in Table 4 in the same manner.

[0160]

Table 4

[0161] (Synthesis of Polymer Compounds bb to ih, cc', and dd') The types and blending amounts of the respective materials used in the synthesis of the polymer compounds were changed from the conditions for synthesizing the polymer compound aa as described in Table 4. Otherwise, based on the same conditions as those for the polymer compound aa, the polymer compounds bb to ih, cc', and dd' were synthesized, and the weight-average molecular weight (Mw: standard polystyrene conversion value by GPC) was measured.

[0162] [Example 1] A conductive paste was prepared as follows, and the physical properties of the dried film obtained using the conductive paste were evaluated.

[0163] 〈Preparation of Conductive Paste〉 As a conductive powder, 47 mass% of Ni powder (Ni-1, number average particle diameter: 0.18 μm), as a ceramic powder, 3.5 mass% of BaTiO3 powder (BT-1, number average particle diameter: 0.05 μm), 3.0 mass% of polymer compound aa, 0.4 mass% of an acrylic polymer dispersant with a carboxyl group (weight average molecular weight: 50000), and the balance of an organic solvent (dihydroterpineol DHT) 46.1 mass% were blended to make a total of 100 mass%. These materials were mixed using a three-roll mill to prepare a conductive paste. The surface roughness, adhesion to a green sheet, and dry film density of the dried film obtained by printing and drying the prepared conductive paste as follows were evaluated.

[0164] [Evaluation Method] (Dispersibility: Surface roughness of the dried film of the conductive paste and adhesion to the green sheet) <Surface Roughness> The prepared conductive paste was screen-printed on a heat-resistant reinforced glass with a size of 2.54 cm (1 inch) square and dried at 120 °C for 1 hour in the air to prepare a dried film with a size of 20 mm square and a film thickness of 1 - 3 μm. When the dispersibility of the conductive paste is good, the surface of the dried film becomes a smooth film. When the dispersibility is poor, aggregation occurs in the conductive paste, the surface of the dried film becomes rough, and the surface smoothness decreases. Therefore, using a laser microscope (OLS-5000 manufactured by Evident Corporation), the surface roughness Sa (arithmetic mean height) of the prepared dried film was measured based on the standard of ISO 25178. The smaller the value of the surface roughness Sa (arithmetic mean height), the smoother the surface of the dried film. The measurement results are shown in Table 5.

[0165] <Adhesion between the Dried Film and the Green Sheet> The prepared conductive paste was printed on a BaTiO3 dielectric green sheet with a size of 2.54 cm (1 inch) square so that the film thickness after printing was 5 to 10 μm. After printing, it was dried at 120 °C for 20 minutes to form a dry film of the conductive paste on the surface of the green sheet. Next, a BaTiO3 dielectric green sheet was placed on the dry film of the conductive paste, and the dry film of the conductive paste and the BaTiO3 dielectric green sheet were thermocompression bonded with a hydrostatic pressure press at 80 °C and 98 MPa to prepare a laminate. The adhesion between the dry film of the conductive paste and the BaTiO3 dielectric green sheet was evaluated by measuring the force required to peel them off. This adhesion was taken as the average of five points measured by a thin film adhesion strength measuring machine (Romulus manufactured by QUAD).

[0166] Specifically explaining the process of adhesion evaluation with a thin film adhesion strength measuring machine, an aluminum stud pin coated with an epoxy adhesive was vertically adhered to the center of the laminate, and an alumina plate coated with an adhesive was adhered to the opposite side. A sample for adhesion evaluation with the stud pin vertically adhered was prepared, and the adhesion between the dry film of the conductive paste and the BaTiO3 dielectric green sheet was evaluated by pulling the stud pin of the sample away from the surface of the laminate. The measurement results are shown in Table 5.

[0167] <Dry film density> 20 mg of nickel paste was dropped in a dome shape on glass and dried in a drying oven at 80 °C for 2 hours. The dry film density was calculated from the volume obtained by a laser microscope (OLS-5000 manufactured by Evident) and the weight difference of the nickel paste before and after drying.

[0168] <Evaluation> Based on the measurement results of the dry film density, surface roughness, and adhesion between the dry film and the green sheet, the performance of the dry film was evaluated as follows. 〇: The dry film density was 5.20 g / cm 3 or more, the surface roughness Sa was 55 nm or less, and all values of adhesion were 8.0 MPa or more were satisfied. ×: The dry film density was 5.20 g / cm3 Among them, there were some that did not satisfy any of the conditions where the surface roughness Sa was 55 nm or less and the adhesion value was 8.0 MPa or more.

[0169] Even in the case of the dielectric layer (e.g., 1.0 μm or less) and the internal electrode layer (e.g., 1.5 μm or less) of the thinned MLCC, if the surface roughness Sa is 55 nm or less, the decrease in the insulation resistance of the dielectric layer due to the unevenness of the internal electrode layer can be suppressed. If the adhesion value is 8.0 MPa or more, even if the dielectric layer and the internal electrode layer are thinned, poor adhesion can be suppressed. Also, regarding the dry film density, if it is 5.20 g / cm 3 or more, the contact area with the dielectric layer can be increased and the capacitance of the MLCC can be increased. Therefore, by satisfying the above conditions, the dielectric layer and the internal electrode layer can be thinned, and it becomes possible to manufacture a smaller and higher-capacity MLCC.

[0170] Table 5 to 7 show the materials used in the conductive paste of Example 1 and their usage amounts, the formulation of the conductive paste, the measured values of the dry film density of the dry film formed using the conductive paste, the measured values of the surface roughness Sa, the measured values of the adhesion, and the above evaluation results (〇 or ×). The formulations and measurement results of Examples 2 to 13 and Comparative Examples 1 to 4 are also shown in the same manner as Example 1.

[0171] [Table 5]

[0172] [Table 6]

[0173] [Table 7]

[0174] [Examples 2 to 13] Based on the formulations shown in Tables 5 and 6, Ni powder, BaTiO3 powder, polymer compound, dispersant, organic solvent, etc. were mixed, and conductive pastes of Examples 2 to 13 were prepared in the same manner as in Example 1. Using the prepared conductive pastes, a dry film was formed in the same manner as in Example 1, and the surface roughness, adhesion to the green sheet, and dry film density of the obtained dry film were measured and evaluated in the same manner as in Example 1.

[0175] [Comparative Examples 1 to 4] Based on the formulations shown in Table 7, Ni powder, BaTiO3 powder, polymer compound, dispersant, organic solvent, etc. were mixed, and conductive pastes of Comparative Examples 1 to 4 were prepared in the same manner as in Example 1. Using the prepared conductive pastes, a dry film was formed in the same manner as in Example 1, and the surface roughness, adhesion to the green sheet, and dry film density of the obtained dry film were measured and evaluated in the same manner as in Example 1.

[0176] [Evaluation Results] The dry films formed with the conductive pastes of Examples 1 to 13 had a dry film density of 5.20 g / cm as shown in Tables 5 and 6 3 or more, and it can be seen that the surface roughness Sa (arithmetic mean height) was 55 nm or less and the adhesion was 8.0 MPa or more. On the other hand, the dry film formed with the conductive paste of Comparative Example 1 had poor adhesion because the polymer compound was not contained in the present invention. The dry film formed with the conductive paste of Comparative Example 2 had poor surface roughness because the molecular weight of the polymer compound was 150,000 or more. The dry film formed with the conductive paste of Comparative Example 3 had poor adhesion because the molecular weight of the polymer compound was less than 30,000. The dry film formed with the conductive paste of Comparative Example 4 had poor surface roughness because the molar ratio of sulfur atoms to the cellulose-based compound exceeded 1.7.

[0177] As described above, the conductive paste of the present invention can provide a conductive paste having a smooth dry film even when using miniaturized conductive powder or ceramic powder, and having excellent adhesion. Therefore, it can be suitably used as a raw material for internal electrodes of multilayer ceramic capacitors, which are chip components (electronic components) of electronic devices such as mobile phones and digital devices, and thus is industrially useful.

Explanation of Signs

[0178] 1 Multilayer ceramic capacitor 10 Ceramic laminate 11 Internal electrode layer 12 Dielectric layer 20 External electrode 21 External electrode layer 22 Plating layer

Claims

1. A conductive paste comprising a conductive powder, a ceramic powder, a dispersant, a binder resin, and an organic solvent, wherein the binder resin contains a polymer compound in which a cellulose-based compound and a polyvinyl acetal-based compound are bonded by a sulfur atom, the molar ratio of the sulfur atoms contained in the polymer compound to the cellulose-based compound is 0.3 to 1.7, and the weight average molecular weight of the polymer compound is 30,000 or more and less than 150,000. A conductive paste.

2. The conductive paste according to Claim 1, wherein the weight average molecular weight of the polymer compound is 60,000 or more and 130,000 or less.

3. The cellulose-based compound is a cellulose derivative having a thiol group or a vinyl group, the polyvinyl acetal-based compound is a polyvinyl acetal resin having a thiol group or a vinyl group, when the cellulose derivative has a thiol group, the polyvinyl acetal resin has a vinyl group that reacts with the thiol group, and when the cellulose derivative has a vinyl group, the polyvinyl acetal resin has a thiol group that reacts with the vinyl group. The conductive paste according to Claim 1 or 2.

4. The cellulose derivative is ethyl cellulose having a thiol group or a vinyl group, and the polyvinyl acetal resin is polyvinyl butyral having a thiol group or a vinyl group. The conductive paste according to Claim 3.

5. The cellulose-based compound is a first esterification reactant obtained by dehydration condensation of a carboxy group of a carboxylic acid having a thiol group or a vinyl group and a hydroxyl group of cellulose, the polyvinyl acetal-based compound is a second esterification reactant obtained by dehydration condensation of a carboxy group of a carboxylic acid having a thiol group or a vinyl group and a hydroxyl group of polyvinyl acetal, when the first esterification reactant has a thiol group, the second esterification reactant has a vinyl group, when the first esterification reactant has a vinyl group, the second esterification reactant has a thiol group, and the polymer compound is a thiol-ene reactant of the first esterification reactant and the second esterification reactant. The conductive paste according to Claim 1.

6. The first esterification reactant is an esterification reactant obtained by dehydration condensation of a carboxy group of 3-allyloxypropionic acid and a hydroxyl group of ethyl cellulose. The conductive paste according to claim 5, wherein the second esterification reactant is an esterification reactant obtained by dehydration condensation of the carboxy group of 3-mercapto propionic acid and the hydroxyl group of polyvinyl butyral.

7. The conductive paste according to claim 1, wherein the binder resin contains at least one of cellulose and polyvinyl acetal.

8. The conductive paste according to claim 1 or 2, wherein the conductive powder is nickel powder.

9. The conductive paste according to claim 1, wherein the number average particle diameter of the conductive powder is 0.05 μm or more and 0.3 μm or less.

10. The conductive paste according to claim 1, wherein the ceramic powder contains barium titanate.

11. The conductive paste according to claim 1, wherein the number average particle diameter of the ceramic powder is 0.01 μm or more and 0.5 μm or less.

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

13. The conductive paste according to claim 1, which is for an internal electrode of a multilayer ceramic component.

14. An electronic component formed using the conductive paste according to claim 1.

15. It has at least a laminate in which a dielectric layer and an internal electrode layer are laminated, The internal electrode layer is a multilayer ceramic capacitor formed using the conductive paste according to claim 1.

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