JP7681985B2 - Ceramic slurry composition and method for manufacturing multilayer ceramic electronic components using same - Google Patents

Description

This disclosure relates to a ceramic slurry composition and a method for manufacturing a multilayer ceramic electronic component using the same.

Multilayer ceramic electronic components such as multilayer ceramic capacitors are known as multilayer electronic components in which dielectric layers and conductor layers are alternately stacked. In multilayer ceramic electronic components, in order to suppress internal loss that occurs when used for high-frequency applications, materials such as silver and copper, which have low melting points and low electrical resistance, are used as materials for the conductor layers. However, because low-resistance materials such as silver and copper have low melting points, they cannot be fired simultaneously with normal ceramic green sheets.

Against this background, ceramic green sheets formed from a ceramic slurry composition containing ceramic powder and a boron compound have been developed as ceramic green sheets that can be co-fired with low-resistance materials. The sintering temperature is reduced by adding a boron compound to the ceramic powder.

However, ceramic green sheets are required to have strength. To form high-strength ceramic green sheets, ceramic slurry compositions have been developed that contain a resin with hydroxyl groups, such as high-strength polyvinyl butyral resin, as a binder component.

For example, Patent Document 1 discloses a slurry composition for ceramic green sheets that contains a ceramic raw material powder containing boron, a binder component having a hydroxyl group, a β-diketone as a chelating agent, and an organic solvent, with the β-diketone content falling within a specific range.

JP 2005-139034 A

However, when a ceramic slurry composition contains a boron compound and a polyvinyl butyral resin, a reaction between the boron compound and the polyvinyl butyral resin proceeds. This reaction can cause gelation, making it difficult to form ceramic green sheets. The slurry composition disclosed in Patent Document 1 does not sufficiently suppress gelation.

Therefore, one aspect of the present invention aims to provide a ceramic slurry composition that suppresses gelation and a method for manufacturing a multilayer ceramic electronic component using the same.

One aspect of the present invention is a ceramic slurry composition that contains a ceramic powder, a boron compound, a binder component containing a polyvinyl butyral resin, an organic solvent containing a monohydric alcohol, and a compound having a 1,2-diol structure.

In one embodiment, the monohydric alcohol may be at least one selected from the group consisting of methanol, ethanol, 1-propanol, and 2-propanol.

In one embodiment, the content of the compound having a 1,2-diol structure may be 2.5 to 100 mass % based on the total amount of boron compounds converted into boric acid (H ₃ BO ₃ ).

In one embodiment, the solubility of the compound having a 1,2-diol structure in 1-propanol at 20°C may be 0.1 g/100 g or more.

In one embodiment, the compound having a 1,2-diol structure may be at least one selected from the group consisting of sugars, sugar alcohols, and sugar acids.

In one embodiment, the compound having a 1,2-diol structure may be at least one selected from the group consisting of sugar alcohols and sugar acids.

In one embodiment, the water content may be 1% by mass or less based on the total amount of the composition.

Another aspect of the present invention is a method for producing a multilayer ceramic electronic component, comprising the steps of: laminating and firing a lamination sheet comprising a ceramic green sheet formed using a ceramic slurry composition and an internal electrode pattern formed on the main surface of the ceramic green sheet to obtain a ceramic body; and forming a terminal electrode on the ceramic body, the ceramic slurry composition containing a ceramic powder, a boron compound, a binder component including a polyvinyl butyral resin, an organic solvent including a monohydric alcohol, and a compound having a 1,2-diol structure.

According to one aspect of the present invention, it is possible to provide a ceramic slurry composition in which gelation is suppressed and a method for manufacturing a multilayer ceramic electronic component using the same.

1 is a diagram illustrating a cross-sectional configuration of a multilayer ceramic electronic component according to one embodiment. 13A and 13B are diagrams illustrating a case where streaks occur in the evaluation of streaks on a sheet.

A preferred embodiment of the present invention will now be described with reference to the drawings. In the drawings, equivalent components are designated by equivalent reference numerals.

[Ceramic Slurry Composition]
The ceramic slurry composition according to this embodiment contains a ceramic powder, a boron compound, a binder component containing a polyvinyl butyral resin, an organic solvent containing a monohydric alcohol, and a compound having a 1,2-diol structure.

The ceramic powder is not particularly limited, and examples thereof include powders of oxides containing titanium and oxides containing zirconium. Specifically, examples thereof include powders of BaTiO ₃ and (Ca, Sr) (Ti, Zr) O _3. These oxides may be calcined. When calcining, the temperature may be, for example, 900°C or higher and 1350°C or lower. The calcination time is preferably, for example, 0.5 to 24 hours. The ceramic powder does not need to be an oxide from the beginning, and may be, for example, a carbonate, a hydroxide, or the like, which becomes an oxide by heat treatment. The ceramic powder may be used alone or in combination of two or more types.

The boron compound is a compound containing boron as a constituent element. Examples of the boron compound include H ₃ BO ₃ , B ₂ O ₃ , and glass containing boron such as boric acid glass. The content of the boron compound converted into boric acid (H ₃ BO ₃ ) may be 0.1 to 20 mass % based on the total amount of the ceramic powder and the boron compound converted into boric acid (H ₃ BO ₃ ).

The ceramic slurry composition according to this embodiment may contain an auxiliary agent. Examples of the auxiliary agent include a magnesium compound containing magnesium as a constituent element, a rare earth element compound containing a rare earth element as a constituent element, a manganese compound containing manganese as a constituent element, a chromium compound containing chromium as a constituent element, a silicon compound containing silicon as a constituent element, an aluminum compound containing aluminum as a constituent element, and a vanadium compound containing vanadium as a constituent element. These compounds may be oxides, carbonates, or hydroxides. The auxiliary agent may be used alone or in combination of two or more.

The content of the auxiliary agent may be 0.1 to 20 mass% based on the total amount of the ceramic powder.

The binder component includes a polyvinyl butyral resin. The content of the polyvinyl butyral resin may be 80% by mass or more, 90% by mass or more, or 100% by mass based on the total amount of the binder component.

The binder component may contain a resin component other than polyvinyl butyral resin. Examples of such resin components include acrylic resin and ethyl cellulose resin.

The content of the binder component may be 4 to 12 mass% based on the total amount of ceramic powder.

The organic solvent includes a monohydric alcohol. The number of carbon atoms in the monohydric alcohol may be, for example, 1 to 10, 1 to 8, or 1 to 5 or less, and from the viewpoint of suppressing gelation, it is preferable that the number of carbon atoms is 1 to 3, and more preferable that the number of carbon atoms is 1 or 2. Examples of monohydric alcohols include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and 2-butanol, and from the viewpoint of suppressing gelation, it is preferable that the number of carbon atoms is methanol, ethanol, 1-propanol, and 2-propanol, and more preferable that the number of carbon atoms is methanol and ethanol.

From the viewpoint of suppressing gelation, the content of the monohydric alcohol is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more, based on the total amount of the organic solvent.

The organic solvent may contain an organic solvent other than a monohydric alcohol. Examples of such organic solvents include hydrocarbon solvents such as mineral spirits, xylene, and toluene, ketone solvents such as methyl ethyl ketone (MEK) and acetone, and ethyl acetate. The organic solvent may be used alone or in combination of two or more.

The organic solvent content may be 100 to 250 mass % based on the total amount of ceramic powder.

A 1,2-diol structure is a structure in which two hydroxyl groups are each bonded to two different adjacent carbons. Examples of compounds having a 1,2-diol structure include sugars, sugar alcohols, sugar acids, and polyhydric alcohols other than sugar alcohols. Examples of sugars include monosaccharides, disaccharides, and polysaccharides. Examples of monosaccharides include heptose (seven carbon sugar), hexose (six carbon sugar), and pentose (five carbon sugar). Examples of heptose include sedoheptulose. Examples of hexose include α-glucose (glucose), β-glucose (glucose), fructose (fruit sugar), galactose, talose, and allose. Examples of pentose include ribulose, apiose, and ribose. Examples of disaccharides include sucrose (sucrose), lactose (milk sugar), maltose (malt sugar), and cellobiose. Examples of polysaccharides include amylose (starch), cellulose, amylopectin, glycogen (animal starch), pectin, and glucomannan. Examples of sugar alcohols include sorbitol, xylitol, and mannitol. Examples of sugar acids include ascorbic acid, glyceric acid, neuraminic acid, glucuronic acid, and tartaric acid. Examples of polyhydric alcohols other than sugar alcohols include ethylene glycol and glycerin.

The compound having a 1,2-diol structure is preferably a sugar, a sugar alcohol, or a sugar acid from the viewpoint of suppressing gelation, and is preferably a sugar alcohol or a sugar acid from the viewpoint of suppressing the occurrence of streaks in the ceramic green sheet obtained using the ceramic slurry composition. The compound having a 1,2-diol structure may be used alone or in combination of two or more kinds.

From the viewpoint of suppressing gelation, the content of the compound having a 1,2-diol structure is preferably 2.5 to 100 mass %, and more preferably 12.5 to 75 mass %, based on the total amount of boron compounds converted into boric acid (H ₃ BO ₃ ).

The solubility of the compound having a 1,2-diol structure in 1-propanol at 20°C is preferably 0.1 g/100 g or more, more preferably 0.2 g/100 g or more, and even more preferably 0.3 g/100 g or more, from the viewpoint of suppressing the occurrence of streaks in the ceramic green sheet obtained using the ceramic slurry composition.

From the viewpoint of suppressing gelation, the number of hydroxyl groups contained in the molecule of the compound having a 1,2-diol structure is preferably 4 or more, and more preferably 5 or more. The number of hydroxyl groups contained in the molecule of the compound having a 1,2-diol structure may be 8 or less.

The molecular weight of the compound having a 1,2-diol structure is preferably 180 or less from the viewpoint of suppressing the occurrence of streaks in the ceramic green sheet obtained using the ceramic slurry composition.

The ceramic slurry composition according to this embodiment may contain other components, such as a plasticizer, a dispersant, and water.

Examples of plasticizers include dioctyl phthalate, benzyl butyl phthalate, diisononyl phthalate, and dioctyl adipate.

Examples of dispersants include alkyl imidazolines and high molecular weight polyester acid amide amine salts.

The water content is preferably 1 mass % or less, and more preferably 0.5 mass % or less, based on the total amount of the ceramic slurry composition, from the viewpoint of suppressing the occurrence of pinholes in the green sheet. The ceramic slurry composition according to this embodiment does not need to contain water.

The ceramic slurry composition according to this embodiment is obtained by mixing a ceramic powder, a boron compound, a binder component, an organic solvent, and a compound having a 1,2-diol structure. The order of mixing is not particularly limited, but from the viewpoint of suppressing gelation, it is preferable to first mix the ceramic powder, the boron compound, and the organic solvent, and then add and mix the binder component. The ceramic powder and the boron compound may or may not be mixed in advance. When the ceramic powder and the boron compound are mixed in advance, the boron compound may be in a state of being attached to the ceramic powder. The ceramic powder may be attached to the ceramic powder by calcination or coating.

<Action and effect>
The ceramic slurry composition according to the present embodiment contains a combination of an organic solvent containing a monohydric alcohol and a compound having a 1,2-diol structure in addition to a boron compound and a polyvinyl butyral resin, and thus gelation can be suppressed compared to a ceramic slurry composition that does not contain an organic solvent containing a monohydric alcohol or does not contain a compound having a 1,2-diol structure. In addition, since the ceramic slurry composition according to the present embodiment contains a boron compound and a polyvinyl butyral resin, it can be fired even at a low temperature and has excellent strength.

[Ceramic electronic components]
Next, an example of a multilayer ceramic electronic component including ceramic layers formed using the ceramic slurry composition according to the above embodiment will be described. Fig. 1 is a schematic diagram showing a cross-sectional configuration of a multilayer ceramic electronic component according to a preferred embodiment. The multilayer ceramic electronic component 100 shown in Fig. 1 includes a ceramic body 3 and terminal electrodes 7 provided on both ends of the ceramic body.

The ceramic body 3 is composed of a plurality of ceramic layers 1 (three layers in this example) formed using the ceramic slurry composition according to the above embodiment, and a plurality of internal electrodes 2 provided between the ceramic layers 1. In other words, the ceramic body 3 is composed of a laminate in which the ceramic layers 1 and the internal electrodes 2 are alternately stacked. In this ceramic body 3, the internal electrodes 2 are provided (drawn out) so that one end of each is exposed on different opposing end faces of the ceramic body 3, and the exposed portions are connected to the terminal electrodes 7.

The material of the internal electrode 2 is not particularly limited. Examples include the metal elements Cu, Ag, Pd, Ni, and Al, and materials (alloys, compounds, etc.) that contain these as main components. Since the ceramic slurry composition of the above embodiment can be fired even at low temperatures, it is preferable that the internal electrode 2 contains Cu and Ag.

A pair of terminal electrodes 7 are provided on the end faces of the ceramic body 3 where the internal electrode 2 is exposed. The terminal electrode 7 includes a base electrode 4, a first layer formed on the base electrode 4, and a second layer formed on the first layer. Examples of materials for the terminal electrode 7 include Cu, Ag, Pd, Ni, Sn, and conductive resin. For example, the terminal electrode 7 may have a base electrode 4 containing Cu, a first layer that is a Ni layer containing Ni, and a second layer that is a Sn layer containing Sn. The terminal electrode 7 may be a single layer without multiple layers.

Next, a preferred embodiment of the method for manufacturing the multilayer ceramic electronic component 100 according to the above embodiment will be described.

The method for manufacturing the laminated ceramic electronic component 100 according to this embodiment includes a step of laminating and firing a laminate sheet including a ceramic green sheet formed using the ceramic slurry composition according to the above embodiment and an internal electrode pattern formed on the main surface of the ceramic green sheet to obtain a ceramic body 3, and a step of forming a terminal electrode 7 on the ceramic body 3.

The ceramic green sheet can be obtained, for example, by applying the ceramic slurry composition according to the above embodiment onto a support sheet and drying the resulting coating.

The support sheet may be, for example, a PET film. The method for applying the ceramic slurry composition is not particularly limited, but may be, for example, a doctor blade method. The drying time is not particularly limited. The drying temperature may be, for example, 60 to 120°C. The thickness of the ceramic green sheet may be 0.5 to 30 μm.

The lamination sheet is obtained by screen printing or the like of a conductive paste on the main surface of a ceramic green sheet to form a pattern of the internal electrode 2.

The firing temperature is preferably 800 to 1085°C, and more preferably 800 to 961°C, since the ceramic slurry composition of the above embodiment is suitable for firing at low temperatures. The firing time may be, for example, 0.5 to 20 hours, or 1 to 10 hours.

The method for forming the terminal electrode is not particularly limited, but may be, for example, the following method. That is, first, a paste containing Cu particles, glass frit, resin, and a solvent is applied to the end surface of the ceramic body 3 to form a coating film. Next, the formed coating film is baked at high temperature to form a Cu sintered body on the end surface of the ceramic body 3. Next, Ni plating is applied to the Cu sintered body to form a Ni layer. Next, Sn plating is applied to the Ni layer to form a Sn layer, thereby forming the terminal electrode.

In the above embodiment, a ceramic capacitor has been described as an example of a multilayer ceramic electronic component, but the present invention is not limited to this. The present invention can also be applied to electronic components such as inductors, varistors, thermistors, LC filters, and resistors, as long as the electronic components have a ceramic body.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples in any way.

[First Consideration]
<Preparation of Composition>
(Example 1-1)
A mixture was obtained by adding spherical stabilized zirconia media with a diameter of 2 mm and the materials shown in Table 1 in the amounts shown in Table 1 to a ball mill and mixing them. Also, 1.89 g of polyvinyl butyral resin (manufactured by Sekisui Chemical Co., Ltd., product name "BH6") and 10.70 g of 1-propanol were mixed to obtain a lacquer in which the polyvinyl butyral resin was dissolved. The lacquer was added to the obtained mixture and mixed to obtain a composition. The proportion of monohydric alcohol in the total amount of organic solvent was 37.0 mass%.

(Comparative Example 1-1)
As shown in Table 1, a mixture was obtained in the same manner as in Example 1-1, except that H ₃ BO ₃ and additives were not added. A polyvinyl butyral resin that had been dissolved in an organic solvent in advance to form a lacquer was added to the mixture and mixed to obtain a composition.

(Comparative Example 2-2)
As shown in Table 1, a mixture was obtained in the same manner as in Example 1-1, except that no additive was added. A polyvinyl butyral resin that had been dissolved in an organic solvent in advance to form a lacquer was added to the mixture, and the mixture was mixed to obtain a composition.

(Examples 1-2 to 1-7 and Comparative Examples 1-3 and 1-4)
A composition was obtained in the same manner as in Example 1-1, except that the additives were changed as shown in Tables 1 and 2. The weight-average molecular weight of the polyethylene glycol used as the additive in Comparative Example 1-4 was 380 to 420.

<Measurement of Viscosity>
(Examples 1-1 to 1-7 and Comparative Examples 1-1 to 1-4)
The viscosity of the resulting composition was measured using a B-type rotational viscometer at a temperature of 25° C. and a rotation speed of 100 rpm. The results are shown in Tables 1 and 2.

[Second Consideration]
(Examples 2-1 to 2-8)
Compositions were prepared in the same manner as in Example 1-3, except that the amount of xylitol was changed as shown in Tables 3 and 4. The viscosity of the obtained compositions was measured in the same manner as in Example 1-3. The results are shown in Tables 3 and 4.

[Third Consideration]
<Preparation of Composition>
(Examples 3-1 to 3-3)
A mixture was obtained by adding spherical stabilized zirconia media having a diameter of 2 mm and the materials shown in Table 5 to a ball mill and mixing them. In addition, 21.13 g of methyl ethyl ketone and 1.91 g of polyvinyl butyral resin (manufactured by Sekisui Chemical Co., Ltd., product name "BH6") were mixed to obtain a lacquer in which the polyvinyl butyral resin was dissolved. The lacquer was added to the obtained mixture in the amount shown in Table 5, and the mixture was mixed in a ball mill to obtain a composition.

(Comparative Example 3-1)
As shown in Table 5, compositions were obtained in the same manner as in Example 3-1, except that no additive was added and methyl ethyl ketone was used instead of 1-propanol to prepare the mixture.

(Comparative Example 3-2)
As shown in Table 5, compositions were obtained in the same manner as in Example 3-1, except that the mixture was prepared without adding any additives.

(Comparative Example 3-3)
As shown in Table 5, compositions were obtained in the same manner as in Example 3-1, except that the mixture was prepared by using methyl ethyl ketone instead of 1-propanol.

<Measurement of Viscosity>
(Examples 3-1 to 3-3 and Comparative Examples 3-1 to 3-3)
The viscosity was measured in the same manner as in Examples 1-1 to 1-7 and Comparative Examples 1-1 to 1-4. The results are shown in Table 5. In the table, "not measurable" indicates that the composition gelled.

[Fourth Consideration]
<Preparation of Composition>
(Examples 4-1 to 4-2 and Comparative Examples 4-1 to 4-4)
A composition was obtained in the same manner as in Example 3-1, except that the materials shown in Table 6 were used.

<Measurement of Viscosity>
(Examples 4-1 to 4-2 and Comparative Examples 4-1 to 4-4)
The viscosity was measured in the same manner as in Example 3-1, and the results are shown in Table 6.

[Fifth Consideration]
<Preparation of Composition>
(Examples 5-1 to 5-5)
A mixture was prepared in the same manner as in Example 1-1, except that the materials shown in Table 7 were charged into the ball mill in the amounts shown in Table 7, instead of the materials shown in Table 1. A composition was prepared in the same manner as in Example 1-1, except that the lacquer in which the polyvinyl butyral resin was dissolved was blended into the mixture in the amounts shown in Table 7. The proportion of monohydric alcohol in the total amount of organic solvent was 42.2 mass%.

<Preparation of Sheet>
(Examples 5-1 to 5-5)
A silicone resin-coated PET film (width: 100 mm) was prepared. The composition obtained was then applied to the PET film using a dam coater. The gap between the PET film and the dam coater was 100 μm for both the inner layer and the outer layer. The composition applied to the PET film was then dried using a dryer to obtain a sheet in which a dry film of the composition was formed on the PET film. The temperature of the dryer was 80° C. The length of the ceramic layer in the TD direction was 80 mm.

<Evaluation of streaks in sheets>
(Examples 5-1 to 5-5)
Cellophane tape (registered trademark) was attached to the obtained sheet in the TD direction. The length of the cellophane tape was set to be equal to or greater than the length of the dry film in the TD direction. Then, the attached cellophane tape was peeled off in the MD direction to peel off a part of the dry film from the PET film. For the dry film that was not peeled off and remained on the PET film, the number of mountain-shaped protrusions indicated by the arrows in FIG. 2 was taken as the number of streaks that occurred on the sheet. The results are shown in Table 7.

<Measurement of solubility of compounds having a 1,2-diol structure>
(Examples 5-1 to 5-5)
1-propanol was placed in a flask as a solvent. The compound having a 1,2-diol structure was added to the 1-propanol until a precipitate remained. The flask was then sealed, thoroughly shaken, and allowed to stand until the supernatant and precipitate were completely separated. The supernatant was transferred to a heat-resistant container and evaporated at 120°C, and the solubility of the compound having a 1,2-diol structure in 1-propanol was calculated from the mass of the supernatant and the mass of the residue after evaporation. The results are shown in Table 7.

<Measurement of Viscosity of Composition>
(Examples 5-1 to 5-5)
The viscosity of the composition was measured in the same manner as in Example 1-1, and the results are shown in Table 7.

1...ceramic layer, 2...internal electrode, 3...ceramic body, 4...base electrode, 5...first layer, 6...second layer, 7...terminal electrode, 100...multilayer ceramic electronic component.

Claims (5)

The ceramic powder contains a ceramic powder, a boron compound, a binder component containing a polyvinyl butyral resin, an organic solvent containing a monohydric alcohol, and a compound having a 1,2-diol structure,
the content of the compound having a 1,2-diol structure is 12.5 to 75 mass% based on the total amount of the boron compound converted into boric acid (H ₃ BO ₃ );
the compound having a 1,2-diol structure is at least one selected from the group consisting of sugars, sugar alcohols, and sugar acids,
the molecular weight of the compound having a 1,2-diol structure is 180 or less,
The ceramic slurry composition , wherein the compound having a 1,2-diol structure has a solubility in 1-propanol at 20° C. of 0.1 g/100 g or more . The ceramic slurry composition according to claim 1, wherein the monohydric alcohol is at least one selected from the group consisting of methanol, ethanol, 1-propanol, and 2-propanol. 3. The ceramic slurry composition according to claim 1 , wherein the compound having a 1,2-diol structure is at least one selected from the group consisting of sugar alcohols and sugar acids. The ceramic slurry composition according to any one of claims 1 to 3 , wherein the water content is 1 mass % or less based on the total amount of the composition. a step of laminating a ceramic green sheet formed using the ceramic slurry composition and a lamination sheet including an internal electrode pattern formed on a main surface of the ceramic green sheet, and firing the laminate to obtain a ceramic body;
forming a terminal electrode on the ceramic body;
Equipped with
the ceramic slurry composition contains a ceramic powder, a boron compound, a binder component containing a polyvinyl butyral resin, an organic solvent containing a monohydric alcohol, and a compound having a 1,2-diol structure;
In the ceramic slurry composition, the content of the compound having a 1,2-diol structure is 12.5 to 75 mass% based on the total amount of the boron compound converted into boric acid (H ₃ BO ₃ ),
the compound having a 1,2-diol structure is at least one selected from the group consisting of sugars, sugar alcohols, and sugar acids,
the molecular weight of the compound having a 1,2-diol structure is 180 or less,
The method for producing a multilayer ceramic electronic component , wherein the compound having a 1,2-diol structure has a solubility in 1-propanol at 20° C. of 0.1 g/100 g or more .

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