KR20100000730A - Method for manufacturing paste for internal electrode of high multi layer ceramic capacitor - Google Patents

Abstract

PURPOSE: A method for manufacturing paste for an internal electrode is provided to reduce residual carbon, to minimize the conversion of nickel oxide(NiO), and to prevent the conductivity of the internal electrode. CONSTITUTION: A method for manufacturing paste for an internal electrode comprises the steps of: preparing nickel(Ni) compound powder; preparing rare earth and additive coating ceramic porous material; mixing a binder, organic solvent and di-2-ethylhexyl phthalate then filtering the mixture to obtain an organic vehicle; homogeneously mixing the nickel(Ni) compound powder, the organic vehicle, and glyceryl monooleic acid with a planetary mixer, and adding sodium cocoyl glutamate to the mixture, and dispersing it at a viscosity of 50,000-90,000 cps with a 3- roll mill to manufacture a nickel(Ni) metal paste; mixing a rare earth coating ceramic porous material, organic vehicle and nonylphenol ethoxylate phosphate ester and then dispersing it at a viscosity of 100-3,000 cps with a basket mill to prepare ceramic porous material slurry; and mixing the nickel(Ni) metal paste and ceramic porous material slurry, filtering the mixture, and removing bubbles.

Description

Method for manufacturing paste for internal electrode of high multi layer ceramic capacitor

The present invention relates to a method for manufacturing the internal electrode paste of MLCC, and more particularly, to the oxidation start temperature when forming the internal electrode of the MLCC using the internal electrode paste through the coating of nickel (Ni) powder and ceramic co-powder. The present invention relates to a method for manufacturing an internal electrode paste for an ultra high capacity MLCC, which can be prevented from being suspended by separation between a ceramic common powder and nickel (Ni) powder.

Internal electrode pastes are used for internal electrodes of chip components such as multi-layer ceramic capacitors (MLCCs) and chip inductors. An example in which an internal electrode paste is used will be described below using MLCC. MLCC is applied by cutting paste for internal electrode on green sheet to form internal electrode, and then stacked, pressed and cut to alternately stack them. The chip is sintered at 1100 to 1400 ° C after degreasing the organic matter in the range of 200 to 700 ° C. After polishing the sintered chip to form an external electrode to produce the MLCC as shown in FIG.

FIG. 1 is a partial cutaway perspective view of a conventional MLCC. As shown in FIG. 1, the MLCC 10 includes a pair of external electrodes connecting the stack 11 and the internal electrodes 12 on which the internal electrodes 12 are formed. 13), and the external electrode 13 is made of conductive metal such as silver (Ag) or copper (Cu). Here, the internal electrode 12 shown in FIG. 1 shows an abnormal state in which the connection is broken.

The laminate 11 is formed by stacking a green sheet (not shown) in which a plurality of internal electrodes 12 are formed. The green sheet is a mixture of a barium titanate (BaTiO ₃ ) -based dielectric material and an organic binder, followed by a doctor blade ( It is manufactured by a doctor blade method, a lip casting method and the like. The laminate 11 was manufactured by stacking 400 layers or less by applying a thickness of 2.0 μm or more of a green sheet to which the particle size of the dielectric material is applied to a size of 300 nm or more. The demand for high capacity MLCCs is increasing, and to solve this problem, we have developed and mass-produced products with more than 1,000 layers by applying the thickness of green sheet less than 2.0㎛.

The internal electrode 12 may be made of silver (Ag), palladium (Pd), platinum (Pt), Ag-Pd alloy (Ag-Pd), etc. Recently, in consideration of economical efficiency, nickel (Ni), copper (Cu) And so on. In forming the internal electrode 12, a screen printing method is generally applied. In order to form the internal electrode 12 by the screen printing method, the internal electrode 12 is applied with a paste.

The paste for the internal electrode 12 is prepared by selecting nickel (Ni) powder prepared by using a wet or dry manufacturing method, and then mixing the ceramic powder and an organic vehicle. In the preparation of the internal electrode paste, a fine powder having a particle size of 200 to 300 nm is used when the thickness of the green sheet is less than or equal to 2.0 μm. In addition, in the case of a ceramic blank for controlling the shrinkage rate, the ceramic powder having a size of 30 to 100 nm is applied to the internal electrode 12.

In the paste for internal electrodes applied to the conventional high-layered MLCC, the ceramic powder may be suspended due to the density difference between the nickel powder and the ceramic powder. In this case, when the ceramic open powder is suspended, when the laminate is sintered at a high temperature of 1100 ° C. or higher, the ceramic powder and nickel (Ni) powder are sintered differently so that the internal electrode is broken, or delamination or crack is observed. Etc. There is a problem that occurs.

In addition, when the nickel (Ni) powder is atomized, it becomes difficult to disperse the powder due to the high energy to agglomerate due to the electrostatic force between the powders, resulting in uneven surface roughness and density of the paste, resulting in low adhesion to the green sheet or internal electrodes. This short circuit causes a problem that the conductivity is lowered and the loss is increased or the capacity of the MLCC is reduced.

In addition, the specific surface area of the powder of nickel (Ni) is increased, and the oxidation start temperature is lowered. Therefore, the binder degreasing temperature cannot be increased, thereby reducing the reliability of residual carbon. The ceramic material is a dielectric material used as a green sheet material. Reacting with magnesium oxide (MgO), manganese oxide (Mn ₃ O ₄ ), and silicon oxide (SiO ₂ ) added to the other forms a different interface between the internal electrode and the dielectric material, thereby lowering the electrical reliability of the MLCC.

Disclosure of Invention An object of the present invention is to provide a method for manufacturing an internal electrode paste of MLCC that can prevent the floating of the ceramic co-powder as well as increasing the oxidation start temperature.

Another object of the present invention is to prevent the floating of the ceramic material powder, the internal electrode that may be generated due to the different sintering of the ceramic material powder and nickel (Ni) powder when the MLCC laminate is hot sintered due to the floating of the ceramic material powder The present invention provides a method for preparing an internal electrode paste for an MLCC that can prevent breakage, delamination, or cracking, and improve electrical reliability.

It is still another object of the present invention to provide a method for manufacturing an internal electrode paste of MLCC which can prevent occurrence of a dielectric material and other phases between an internal electrode and a dielectric material by coating rare earth on nickel (Ni) powder or ceramic co-powder. Is in.

In the method of manufacturing the internal electrode paste of the MLCC of the present invention, nickel (Ni) is mixed by mixing 60 to 90 wt.% Of nickel (Ni) powder and 10 to 40 wt.% Of rare earth coated nickel (Ni) powder coated with rare earth metal oxide. Preparing a mixed powder; coating a rare earth metal oxide and an additive on the surface of the ceramic powder; and preparing a rare earth and additive coated ceramic powder, 1 to 20% by weight of binder and 40 to 80% of organic solvent. % And DOP (di-2-ethylhexyl phthalate) with a plasticizer and mixed with 0.1 to 2% by weight to prepare an organic vehicle, a nickel (Ni) mixed powder, an organic vehicle and a glyceryl monooleic acid ( Homogeneously mix glycerol-alpha-monooleate with a planetary mixer and add sodium cocoyl glutamic acid as a sedimentation agent to achieve a 3-roll mill at a viscosity of 50,000 to 90,000 cps. Preparing a nickel (Ni) metal paste by dispersing, mixing a rare earth-coated ceramic powder, an organic vehicle, and a nonylphenol ethoxylate phosphate ester with a dispersant to obtain a basket mill at a viscosity of 100 to 3,000 cps. preparing a ceramic slurry by dispersing it in a basket mill), and mixing 40 to 60 weight% of a nickel (Ni) metal paste with 40 to 60 weight% of a ceramic slurry, and filtering and removing bubbles. It is characterized by consisting of a step of preparing a paste.

In the method for preparing the internal electrode paste of the MLCC of the present invention, a nano-coating layer is formed on nickel (Ni) powder using glyceryl monooleic acid to increase the oxidation start temperature to increase the binder degreasing temperature to reduce residual carbon, and nickel oxide (NiO). By minimizing the change to) provides an advantage that can prevent the conductivity of the internal electrode is lowered.

In addition, by adding sodium cocoyl glutamic acid, an amino acid metallic surfactant, the flocculation and dispersion of nickel (Ni) powders and ceramic fillers are optimized to prevent flocculation and dispersion of the ceramic filler powders, thereby preventing the floating of ceramic filler powders. This provides the advantage of obtaining excellent paste properties.

In addition, through the rare earth-based coating on the metal powder and the ceramic material, when the MLCC laminate is sintered at high temperature, the interfacial reaction between the dielectric ceramic and the internal electrode minimizes the nonuniformity of the dielectric ceramic composition, thereby improving reliability and reducing nickel. ) It provides an advantage of preventing breakage, delamination or cracking of the internal electrode, which may be caused by different sintering of the powder and the ceramic common powder.

An embodiment of the paste manufacturing method of the present invention will be described with reference to the accompanying drawings.

2 is a flowchart illustrating a method of manufacturing an internal electrode paste of an MLCC of the present invention.

As shown in FIG. 2, the method for preparing the internal electrode paste of the MLCC (10: shown in FIG. 1) of the present invention first includes 60-90 wt.% Nickel (Ni) powder and rare earth-coated nickel (coated with rare earth metal oxide). Ni) 10 to 40% by weight of the powder is mixed to prepare a nickel (Ni) mixed powder (S10).

To prepare a nickel (Ni) mixed powder, first, a nickel (Ni) powder is prepared (S11). The nickel (Ni) powder prepared in this step (S11) is a powder prepared by a dry method is used nickel (Ni) powder is not coated with an organic material, the particle size of the powder is prepared to be about 100 to 400nm. As such, nickel (Ni) powder manufactured by a dry method, which is not coated with organic materials, can be purchased at a lower cost than a wet method, and thus manufacturing cost can be reduced when manufacturing the internal electrode paste of the MLCC 10. Here, the dry method, which is a method of manufacturing nickel (Ni) powder, is well known in the art (chemical vapoor deposition (CVD) method, PVD (physical vapor deposition) method), so a detailed description thereof will be omitted.

When nickel (Ni) powder is prepared, yttrium oxide (Y ₂ O ₃ ), erbium oxide (Er ₂ O ₃ ), holmium oxide (Ho ₂ O ₃ ), and dysprosium oxide (Dy ₂ O ₃ ) are formed on the surface of the nickel (Ni) powder. One rare earth metal oxide is selected and coated using one of self propagation high-temperature synthesis (SHS) and electron beam (EB) deposition (S12). The rare earth metal oxide coated on the surface of the nickel (Ni) powder in the preparation of the rare earth coated nickel (Ni) powder is 5 to 50 nm.

When the rare earth-coated nickel (Ni) powder is manufactured using the SHS method or the EB deposition method, 60 to 90 weight% of the nickel powder and 10 to 40 weight% of the rare earth coated nickel powder are mixed ( S13) Mixing nickel (Ni) (S13) to prepare a nickel (Ni) mixed powder.

While preparing a nickel (Ni) mixed powder through the above process, a rare earth metal oxide and an additive are coated on the surface of the ceramic powder to prepare a rare earth and additive coating ceramic powder (S20).

In order to control the sintering shrinkage by the ceramic powder, but in order to minimize the reaction between the internal electrode 12 and the dielectric material of the green sheet when applying a material of 100 nm or less, first, to prepare a rare earth-coated ceramic powder, The ceramic powder is prepared (S21). Here, the material of the ceramic powder is the same material as the laminate 11 of MLCC (10), but barium titanate (BaTiO ₃ ), barium zirconium titanate (Ba (TiZr) O ₃ ), BaTiO ₃ -Y ₂ O ₃ ( One of the rare earth system) -MgO-Mn ₃ O ₄ -SiO ₂ system is selected and applied, and the particle size is prepared in the range of 30 to 200 nm.

When the ceramic common powder is prepared, the rare earth metal oxide and the additive are coated (S22) to prepare a rare earth and additive coated ceramic common powder. Rare Earth and Additive Coating The thickness of the rare earth and additives coated on the surface of the ceramic powder when the ceramic powder is manufactured is 5 to 50 nm, and the materials of the rare earth metal oxides are yttrium oxide (Y ₂ O ₃ ) and erbium oxide (Er ₂ O). ₃ ), one of holmium oxide (Ho ₂ O ₃ ), dysprosium oxide (Dy ₂ O ₃ ) is applied, the additives are magnesium oxide (MgO), manganese oxide (Mn ₃ O ₄ ), silicon oxide (SiO ₂ ) Add. The rare earth metal oxide and the additive is coated with one of the SHS method and the EB deposition method, and the rare earth metal oxide and the additive are coated on the ceramic powder to have the same composition as the dielectric ceramic which is the material of the green sheet of the laminate 11. do.

Coating the rare earth metal oxide on the nickel (Ni) powder or the ceramic powder as described above improves electrical reliability and dielectric properties by preventing the formation of a secondary phase at the interface of the internal electrode 12 (shown in FIG. 1). There is. For example, when X7R, a green sheet material, is applied, barium titanate (BaTiO ₃ ) is castable and yttrium oxide (Y ₂ O ₃ ), magnesium oxide (MgO), and manganese oxide (Mn ₃ O ₄ ) as additives. ), Silicon oxide (SiO ₂ ), glass frit, etc. are added, and glass frit (BaTiO ₃ ) having a particle size of 200 nm is applied to prepare a high-capacity MLCC, particularly in high lamination. Since glass frit is difficult to use as a low-temperature sintering aid, low-temperature sintering is applied by applying silicon dioxide (SiO ₂ ) having a particle size of 100 nm or less.

X7R (BaTiO ₃ -Y ₂ O ₃ -MgO-Mn ₃ O ₄ -SiO ₂ ) and the internal electrode (12: FIG. 1), which are materials of the green sheet, are sintered using silicon oxide (SiO ₂ ) or less at 100 nm or lower Nickel (Ni) applied for the purpose of reacting with each other to form a secondary phase at the electrode interface of the internal electrode 12 (shown in FIG. 1) to lower the insulation characteristics and reliability. In order to improve this, by coating rare earth on nickel (Ni) powder or ceramic powder, the secondary phase is prevented from being formed at the interface of the internal electrode 12, thereby improving electrical reliability and dielectric properties. That is, by coating rare earth on nickel (Ni) powder or ceramic powder, it is possible to improve the electrical reliability and dielectric properties of the MLCC by preventing the dielectric material and other phases from being generated between the internal electrode 12 and the dielectric material.

Through the above process, a nickel (Ni) mixed powder and a rare earth and additive coating ceramic co-powder are prepared as well as an organic vehicle (S30).

An organic vehicle is prepared by mixing 1 to 20% by weight of a binder, 40 to 80% by weight of an organic solvent and 0.1 to 2% by weight of di-2-ethylhexyl phthalate (DOP) with a plasticizer, followed by filtration. Cartridge filter of 1 탆 is applied.

The binder used in the preparation of the organic vehicle uses ethyl cellulose (Ethyl Cellulose, EC), and a resin having a molecular weight of 180,000 to 300,000 is used. These binders have good compatibility with terpineol series when terpineol series is used as an organic solvent, so they are well dissolved and have high adhesive strength. In addition, the organic solvent is applied to one of terpineol (Terpineol), alpha terpineol (α-Terpineol), dihydro terpineol (Dethydro-Terpineol), dihydro terpineol acetate (Dethydro-Terpineol-Acetate) do. In the case where terpineol is applied as the organic solvent, when applying the conductive paste for the inner electrode to the green sheet, a hydrocarbon-based low-attack and low-cost attack is applied.

The plasticizer is phthalic acid-based DOP (di-2-ethylhexyl phthalate) is applied. Such a plasticizer softens the binder, ie, ethyl cellulose, which aggregates with a strong intermolecular force, thereby improving printability.

Nickel (Ni) Mixed Powder and Rare Earth Coated Ceramic Powders and organic vehicles are prepared. After the addition of sodium cocoyl glutamic acid as a sedimentation inhibitor to disperse in a three-roll mill (roll mill) at a viscosity of 50,000 to 90,000cps to prepare a nickel (Ni) metal paste (S40).

In the preparation of nickel (Ni) metal paste, 30 to 70% by weight of nickel (Ni) mixed powder, 10 to 50% by weight of organic vehicle, glycerol-alpha-monooleate as a dispersant, and a chemical formula: CH ₃ (CH ₂ ) ₇ CH = CH (CH ₂ ) ₇ COOCH ₂ CCH ₂ OHH) 0.1-3 wt.% And sodium cocoyl glutamic acid, an amino acid metallic surfactant that is an antisettling agent (the chemical formula is shown in FIG. 3) As the pH of 0.1 to 9.0, 0.1 to 5% by weight is added.

Glyceryl monooleic acid can act as an organic coating film to prevent a decrease in the reliability of MLCC (10: shown in FIG. 1), which may be generated by carbon remaining due to failure to increase the binder degreasing temperature. Surfactant to which sodium cocoyl glutamic acid, an amino acid metallic surfactant is applied, is adsorbed on the surface of particles to improve the dispersibility by interfering with the adsorption between powders by electrostatic force or tin g (such as polymer film) between particles. The difference in density is added to prevent the ceramic powder from floating. That is, the ceramic powder is prevented from being suspended by optimizing the aggregation and dispersion caused by the specific gravity difference and the ion difference between the nickel powder and the ceramic powder.

In addition, when the nickel (Ni) metal paste is manufactured, a difference in density occurs between the nickel (Ni) powder and the ceramic powder due to the deterioration of the wettability of the nickel (Ni) powder. In the sintering of the laminate 11 (shown in FIG. 1), the ceramic material and the nickel (Ni) powder are sintered differently so that the internal electrode 12 (shown in FIG. 1) is broken or the laminate 11 is delaminated ( Prevent delamination or cracking.

Non-phenolic ethoxylate phosphate esters are mixed with rare earth-coated ceramic powders, organic vehicles, and dispersants with the manufacture of nickel (Ni) metal pastes, into basket mills at a viscosity of 100 to 3,000 cps. Dispersion to prepare a ceramic slurry (S50). That is, the ceramic paste is prepared by dispersing low viscosity (100 to 3,000 cps). At the time of manufacture of a ceramic slurry, 30-70 weight% of ceramic powders, 10-50 weight% of an organic vehicle, and 0.1-5 weight% of nonylphenol ethoxylate phosphate esters are mixed with a dispersing agent.

When the nickel (Ni) metal paste and the ceramic paste are prepared, 40 to 60 wt.% Of the nickel (Ni) metal paste and 40 to 60 wt.% Of the ceramic paste are mixed, followed by filtration and air bubbles to remove the internal electrode paste. To manufacture (S60). Paste mixing is a three-roll mill and when the internal electrode paste is prepared, it is first filtered through a 400 mesh filter and then secondly filtered through a 1400 to 2000 mesh filter. The internal electrode paste, which has been filtered, is manufactured to remove microbubbles in a vacuum state again so that the paste becomes homogeneous, thereby completing the internal electrode paste preparation of MLCC. The viscosity of the final paste is adjusted to 12,000 to 25,000 cps using a solvent and diluent.

The internal electrode paste manufacturing method of the highly laminated MLCC of the present invention can be applied to the field of manufacturing a high capacity MLCC by laminating a multilayer dielectric of a thin film. In particular, it can be applied to the production of electronic component electrodes that require high reliability, and can be applied as a paste manufacturing method with excellent dispersibility and low cost.

1 is a partial cutaway perspective view of a conventional MLCC,

2 is a flow chart showing a method for manufacturing an internal electrode paste of the MLCC of the present invention;

3 is a chemical formula of sodium cocoyl glutamic acid used as a dispersant in the nickel (Ni) metal paste shown in FIG.

Claims (8)

Preparing a nickel (Ni) mixed powder by mixing 60 to 90 weight% of nickel (Ni) powder and 10 to 40 weight% of rare earth coated nickel (Ni) powder coated with rare earth metal oxide; Preparing a rare earth and additive coated ceramic common powder by coating a rare earth metal oxide and an additive on the surface of the ceramic common powder; Preparing an organic vehicle by mixing 1 to 20% by weight of a binder, 40 to 80% by weight of an organic solvent and 0.1 to 2% by weight of di-2-ethylhexyl phthalate (DOP) with a plasticizer, followed by filtration; Homogeneously mix glycerol-alpha-monooleate with the nickel (Ni) mixed powder, the organic vehicle and the dispersant with a planetary mixer, and then add sodium cocoyl glutamic acid as a sedimentation inhibitor. Dispersing in a 3-roll mill at a viscosity of 50,000 to 90,000 cps to produce a nickel (Ni) metal paste; Non-phenol ethoxylate phosphate ester is mixed with the rare earth-coated ceramic powder and the organic vehicle and a dispersant to disperse into a basket mill at a viscosity of 100 to 3,000 cps to prepare a ceramic powder slurry. Steps, MLCC, characterized in that for preparing the internal electrode paste by mixing 40 to 60% by weight of the nickel (Ni) metal paste and 40 to 60% by weight of the ceramic common slurry, followed by filtration and air bubbles. Method for producing paste for internal electrodes The method of claim 1, wherein the preparing of the nickel (Ni) mixed powder comprises preparing a nickel (Ni) powder; Rare earth metal oxide of one of yttrium oxide (Y ₂ O ₃ ), erbium oxide (Er ₂ O ₃ ), holmium oxide (Ho ₂ O ₃ ), and dysprosium oxide (Dy ₂ O ₃ ) on the surface of the nickel (Ni) powder Selecting and coating by using one of the self propagation high-temperature synthesis (SHS) method and the electron beam (EB) deposition method, 60 to 90% by weight of the nickel (Ni) powder and 10 to 40% by weight of rare earth-coated nickel (Ni) powder is mixed. The nickel (Ni) powder is manufactured by a dry method and has a particle size of 100 to 400 nm, and the thickness of the rare earth metal oxide coated on the surface of the rare earth coated nickel (Ni) powder is 5 to 50 nm. Method for manufacturing paste for The method of claim 1, wherein the preparing of the rare earth and the additive coated ceramic common powder comprises the steps of preparing a ceramic common powder; When the ceramic co-powder is prepared consists of coating a rare earth metal oxide and additives, The material of the ceramic powder is barium titanate (BaTiO ₃ ), barium zirconium titanate (Ba (TiZr) O ₃ ), BaTiO ₃ -Y ₂ O ₃ (rare earth system) -MgO-Mn ₃ O ₄ -SiO ₂ system One is applied, the particle size is 30 to 200nm, the thickness of the rare earth and additives coated on the ceramic co-powder powder is a method for producing an internal electrode paste of MLCC, characterized in that 5 to 50nm. The rare earth metal oxide of claim 3, wherein the rare earth metal oxide is coated with yttrium oxide (Y ₂ O ₃ ), erbium oxide (Er ₂ O ₃ ), holmium oxide (Ho ₂ O ₃ ), and dysprosium oxide. One of (Dy ₂ O ₃ ) is applied, the additive is magnesium oxide (MgO), manganese oxide (Mn ₃ O ₄ ), silicon oxide (SiO ₂ ) is applied, the rare earth metal oxide and the coating method of the additive is SHS method And EB deposition method of the internal electrode paste of the MLCC, characterized in that applied. The method of claim 1, wherein in the manufacturing of the organic vehicle, the binder is one of ethyl cellulose, butyral, and acryl. The organic solvent is terpineol, alpha terpineol, dihydro terpine. Method for producing an internal electrode paste of MLCC, characterized in that one of all, dihydro terpineol acetate is applied. The method of claim 1, wherein a 1 μm cartridge filter is applied during filtration in the manufacturing of the organic vehicle. The method of claim 1, wherein the acidity of sodium cocoyl glutamic acid in the step of manufacturing the nickel (Ni) metal paste is prepared for the internal electrode paste of MLCC, characterized in that the pH is applied from 7.0 to 9.0 Way. The method of claim 1, wherein the viscosity of the internal electrode paste in the step of preparing the internal electrode paste is 12,000 ~ 25,000 cps, the internal electrode paste manufacturing method of the MLCC.

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