JP2021160947A - Method for manufacturing electrode, and method for manufacturing laminated electronic component - Google Patents

Abstract

To provide a method for forming electrode on the surface of a substrate and a method for manufacturing laminated electronic component in which problems caused by solvent or de-binder can be avoided.SOLUTION: A method for manufacturing electrode includes supplying a carrier gas and a metal powder into a plasma gas that is plasmanized in advance under atmospheric pressure, and mixing to form a metal powder-containing plasma gas, and spraying the metal powder-containing plasma gas onto the surface of a substrate to form an electrode precursor on the surface of the substrate and obtain a substrate with electrode precursor, and calcining the substrate with electrode precursor to form an electrode on the surface of the substrate.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for forming an electrode on the surface of a base material and a method for forming a laminated electronic component using a base material on which a precursor of an electrode is formed.

A thick-film conductor paste containing metal powder, binder resin, and solvent is screen-printed on the surface of the base material, the solvent is volatilized by heating, etc., the metal powder and binder resin are fixed to the base material, and then the metal powder and binder resin are removed by firing. The thick film technique of forming a thick film electrode by adhering a metal powder to a base material by fusing with a binder has been widely applied to electronic parts.

When firing a thick-film conductor paste, there is a debinder process in which the binder resin is burned or decomposed to gasify. The gas generated during the debindering process can cause defects in the thick film electrodes.

FIG. 2 is a cross-sectional view of a multilayer ceramic capacitor (MLCC). The MLCC is configured by alternately laminating a porcelain dielectric 11 made of barium titanate or the like and an internal electrode 12 made of nickel, palladium or the like, and silver powder and a thermosetting resin are mixed at both ends of the laminated body. A terminal electrode 13 is provided.

In MLCC, a thick film conductive paste for forming an internal electrode is printed on a green sheet formed of a ceramic powder such as barium titanate powder, a solvent, and a binder resin, and a green sheet printed with the thick film conductive paste is laminated. It is produced by crimping, and then simultaneously firing the green sheet and the thick film conductive paste. Therefore, it is necessary to prevent cracks due to the gas generated by the debinder during firing.

On the other hand, Japanese Patent Application Laid-Open No. 2009-088410 discloses a technique relating to a resin that suppresses cracks due to debindering. In addition to MLCCs, laminated electronic components such as chip inductors and low-temperature co-fired ceramics (LTCC) substrates need to prevent cracks due to gas generated by debindering.

When a green sheet is used as the base material, when the thick film conductor paste is printed, a sheet attack phenomenon occurs in which the solvent of the thick film conductor paste dissolves the binder resin of the green sheet of the base material, and the green sheet may be wrinkled. be.

On the other hand, Japanese Patent Application Laid-Open No. 2010-287763 discloses a technique for conducting a conductive paste that suppresses sheet attack. Also, when a fired ceramic substrate such as an alumina substrate is used as the substrate, if the solvent contained in the thick film conductor paste is inappropriate, bleeding of the solvent may occur around the printed thick film conductor paste. May occur.

Japanese Patent Application Laid-Open No. 2009-088410 JP-A-2010-287763

The present invention provides a method for forming an electrode on the surface of a base material and a base material on which a precursor of the electrode is formed, which can avoid problems caused by a solvent or debinder of a conventional thick-film conductor paste. It is an object of the present invention to provide a method for forming a laminated electronic component used.

The method for manufacturing an electrode of the present invention
A process of supplying a carrier gas and a metal powder into a plasma gas that has been pre-plasma-ized under atmospheric pressure and mixing them to form a plasma gas containing the metal powder.
A step of spraying the metal powder-containing plasma gas onto the surface of the base material to form an electrode precursor on the surface of the base material to obtain a base material with the electrode precursor, and
A step of firing the base material with an electrode precursor to form an electrode on the surface of the base material, and
It is characterized by having.

As the metal powder, it is preferable to use at least one selected from gold powder, silver powder, palladium powder, copper powder, nickel powder, aluminum powder, silver-palladium alloy powder, copper alloy powder, and aluminum alloy powder.

It is preferable that the metal powder-containing plasma gas contains an inorganic oxide powder.

As the inorganic oxide powder, at least one selected from aluminum oxide powder, zinc oxide powder, titanium oxide powder, murite powder, barium titanate powder, lead zirconate titanate powder, and silicic acid-based glass powder is used. Is preferable.

It is preferable to obtain the plasma gas by plasmaizing at least one selected from argon, helium, nitrogen, oxygen, and air.

As the carrier gas, it is preferable to use at least one selected from argon, helium, and nitrogen.

A ceramic green sheet can be used as the base material. Further, an alumina substrate or a glass substrate can also be used as the base material.

In the method for manufacturing a laminated electronic component of the present invention, a ceramic green sheet is used as the base material, and in the method for manufacturing an electrode of the present invention, after the step of obtaining the base material with the electrode precursor, the base material with the electrode precursor is used. It is characterized in that a laminated electronic component is obtained by laminating, and then firing the base material with an electrode precursor to form an electrode on the surface of the base material.

According to the present invention, a metal powder can be fixed to the surface of a base material to form an electrode precursor without using a solvent or a binder, and the electrode precursor is fired to form an electrode on the surface of the base material. Can be formed. As described above, in the present invention, since the electrode can be formed without using a solvent or a binder, it is possible to avoid problems caused by the solvent or debinder of the conventional thick film conductor paste.

As described above, according to the present invention, a solvent or a binder is not required for electrode formation, and an electrode for an electronic component and a laminated electronic component can be produced with a high yield.

FIG. 1 is a flow chart illustrating an outline of an example of a method for manufacturing an electrode (laminated electronic component) of the present invention. FIG. 2 is a cross-sectional view of a multilayer ceramic capacitor (MLCC). FIG. 3 is a schematic view showing an example of a pattern in which an electrode precursor is arranged on the surface of a green sheet when MLCC is manufactured.

As shown in FIG. 1, the electrode manufacturing method of the present invention supplies a carrier gas and a metal powder into a plasma gas that has been pre-plasmaized under atmospheric pressure and mixes them to form a metal powder-containing plasma gas. Step (S1) and a step (S2) of spraying the metal powder-containing plasma gas onto the surface of the base material to form an electrode precursor on the surface of the base material to obtain a base material with the electrode precursor. , And a step (S4) of firing the base material with the electrode precursor to form an electrode on the surface of the base material.

Further, in the method for manufacturing a laminated electronic component of the present invention, a ceramic green sheet is used as the base material, and in the method for manufacturing an electrode of the present invention, after the step of obtaining the base material with the electrode precursor, the group with the electrode precursor is used. It is characterized in that a laminated electronic component is obtained by providing a step (S3) of laminating materials and then performing a step of firing the base material with an electrode precursor to form an electrode on the surface of the base material. And.

In the present invention, the carrier gas and the metal powder are supplied and mixed in the plasma gas converted into plasma to form the plasma gas containing the metal powder. The surface of each particle constituting the metal powder in contact with the plasma gas turned into plasma reacts and is activated. When the inorganic oxide powder is added together with the metal powder, the surfaces of the particles constituting the inorganic oxide powder and the oxides, hydroxides, and carbon dioxide compounds present on the surface react and are activated. These materials are oxidized if the plasma gas is oxygen plasma and reduced if the plasma gas is nitrogen plasma.

In the case of only metal particles, the surface-activated metal particles are sprayed onto the base material, so that they physically bite into the surface of the base material or react with the surface of the base material. It is fixed to the material. When the inorganic oxide powder is contained, the particles constituting the inorganic oxide powder adhere to the base material or the particles constituting the metal powder deposited on the surface of the base material to form the metal particles and the base material. Stick.

As described above, the present invention differs from the conventional technique using the thick-film conductor paste in that the metal powder is fixed to the base material even if it does not contain the binder resin. In the present invention, since the binder resin for fixing the metal powder to the base material is not used, the debinder gas is not generated in the firing step of the electrode precursor.

In the conventional thick-film conductor paste containing a binder resin, a debinder gas is generated in the firing step, and further, the catalytic activity of the metal powder on the binder resin causes a rapid decomposition reaction and combustion of the binder to cause the debinder gas. In addition, there may be a problem that pinholes on the electrode surface and cracks in the laminated electronic component occur due to these problems. However, in the present invention, the problem caused by the generation of these debinder gas does not occur.

Further, in the present invention, since the electrode precursor does not contain a solvent, it is possible to prevent the green sheet attack of the base material and the occurrence of bleeding due to the solvent, which have occurred when a conventional thick film conductor paste containing a solvent is used. Will be done.

Hereinafter, based on an example of the embodiment of the present invention, the metal powder-containing plasma gas forming step (S1), the electrode precursor forming step (S2), the laminating step (S3), and the firing step (S4) will be described in this order.

(1) Metal powder-containing plasma gas forming step In the metal powder-containing plasma gas forming step, a carrier gas and a metal powder are supplied to a plasma gas that has been pre-plasma-ized under atmospheric pressure, mixed, and the metal powder-containing plasma is formed. This is a step (S1) of forming a gas.

(1-1) Metal powder The metal powder is selected in consideration of the characteristics of the electrode and the firing process. The metal powder is preferably selected from gold powder, silver powder, palladium powder, copper powder, nickel powder, aluminum powder, silver-palladium alloy powder, copper alloy powder, and aluminum alloy powder. Considering the characteristics of electrodes, silver powder and copper powder are used for applications that require conductivity, and copper alloy powder and silver-palladium alloy powder such as Constantan and Monel are used for applications that require electrical resistance. For applications that require chemical resistance, gold powder, palladium powder, silver-palladium alloy powder, and copper alloy powder such as Monel can be used, respectively.

Further, when a green sheet is used as the base material and the electrode precursor and the base material are fired at the same time, it is necessary to select the metal powder in consideration of the melting temperature of the metal in the firing step. In particular, when the base material is a ceramic green sheet such as barium titanate for MLCC use, it is desirable to use palladium powder or nickel powder from the firing temperature of the green sheet.

The shape of the metal powder may be spherical, scaly, mixed powder of spherical and scaly, etc., but if it can be sprayed on the surface of the base material, it is limited to or among these. The shape of the metal powder can be appropriately selected without being carried out.

When a spherical metal powder is used, the cumulative volume particle size D ₅₀ (median diameter) of the metal powder is preferably 10 μm or less, more preferably 5 μm or less, and further preferably 0.1 μm or more and 3 μm or less. desirable. If the D _{50 of the} metal powder exceeds 10 μm, defects or pinholes may occur in the finally obtained electrode, and the effective area of the electrode calculated from the metal occupying the electrode may become too small. Further, if the D _{50 of} the metal powder exceeds 10 μm, the film thickness of the obtained electrode exceeds 10 μm, and when the element is formed on the base material so as to cover a part of the surface of the electrode, a step is formed on the element. Is not preferable because it causes cracks in the element.

Further, the electrode precursor is formed by depositing the sprayed metal powder on the surface of the base material. Therefore, a gap is generated between the particles constituting the metal powder. This gap becomes larger as _{the D 50 of} the metal powder becomes larger. To explain the process of sintering the metal powder of the electrode precursor in more detail in the firing step, the particles constituting the metal powder are fused and the particles are connected to each other to form an electrode. Therefore, if the D _{50 of} the metal powder exceeds 10 μm, the gaps between the particles of the metal powder of the electrode precursor become too large, and the gaps between the particles cannot be filled only by fusing the particles. As a result, electrode defects and pinholes may be formed. From this point of view, _{D 50} of the metal powder is limited to 10μm or less.

On the other hand, _{if the D 50 of} the metal powder is 0.1 μm or more, it can be easily handled industrially.

When applied to the internal electrode application of MLCC, the D ₅₀ of the metal powder is preferably 0.1 μm or more and 1.0 μm or less.

When the spherical metal powder is used, as described above, a gap is generated between the particles of the metal powder of the electrode precursor. From the viewpoint of suppressing such gaps, it is also beneficial to use scaly metal powder. When using scaly metal powder, it is necessary to align the orientation of each particle constituting the metal powder. As a means for aligning this orientation, for example, when laminating a base material with an electrode precursor on a base material using a green sheet, which will be described later, the orientation can be made by the pressure of crimping at the time of laminating.

It is also possible to use a spherical metal powder and a scaly metal powder together. This makes it possible to reduce the gaps between the particles that occur when only spherical metal powder is used. Further, by mixing metal powders having different particle sizes, the gaps between the particles can be reduced.

(1-2) Inorganic oxide powder The inorganic oxide powder can be contained in the metal powder-containing plasma gas from the viewpoint of controlling the sintering behavior of the electrode precursor and improving the adhesion between the electrode and the base material. The inorganic oxide powder is mixed with the metal powder and introduced into the plasma gas by the carrier gas. The inorganic oxide powder also comes into contact with the plasma gas, and the surfaces of the particles constituting the inorganic oxide powder and the oxides, hydroxides, and carbon dioxide compounds present on the surface react with each other to activate the inorganic oxide powder.

The inorganic oxide powder is preferably selected from aluminum oxide powder, zinc oxide powder, titanium oxide powder, mullite powder, barium titanate powder, lead zirconate titanate powder, and silicic acid-based glass powder.

When a green sheet is used as the base material, it is more desirable to use aluminum oxide powder, zinc oxide powder, titanium oxide powder, mullite powder, barium titanate powder, and lead zirconate titanate powder among these inorganic oxide powders. When a green sheet is used as the base material, the base material and the electrode precursor are fired at the same time. Sintering of the electrode precursor starts shrinkage due to sintering at a lower temperature than the green sheet. That is, in the firing step, the electrode precursor begins to shrink from the green sheet. The inorganic oxide has the effect of inhibiting the shrinkage of the electrode precursor in the firing step and matching the shrinkage of the electrode precursor in the firing step with the shrinkage of the green sheet.

When a ceramic substrate such as an alumina substrate, a silicon nitride substrate, or an aluminum nitride substrate, or a soda lime glass substrate or a glass ceramic substrate is used as the base material, a silicic acid-based inorganic oxide powder is used to improve the adhesion between the electrode and the base material. Glass powder can be used. In the firing process, silicic acid-based glass reacts with the base material and chemically bonds. Examples of the silicate-based glass powder include lead borosilicate glass powder, bismuth-based borosilicate glass powder, zinc borosilicate-based glass powder, calcium borosilicate-based glass powder, and barium borosilicate glass powder. SiO ₂ component constituting these glasses constitute the glass _{skeleton, PbO, B 2 O 3,} RO (R is an alkaline earth element) adjusts the meltability of glass. Further, for the purpose of adjusting the weather resistance of the glass and the fluidity during firing, it is selected from Al ₂ O ₃ , ZrO ₂ , TIO ₂ , SnO ₂ , ZnO, Li ₂ O, Na ₂ O, K ₂ O and the like. It can contain one or more kinds. Al ₂ O ₃ easily suppresses the phase separation of the glass, ZrO ₂ and TiO ₂ improve the weather resistance of the glass, and SnO ₂ , ZnO, Li ₂ O, Na ₂ O, K ₂ O and the like flow the glass. It has a function to enhance sex.

Glass can generally be produced by mixing predetermined components or precursors thereof according to the desired formulation, melting the resulting mixture and quenching. The heating temperature of the glass at the time of melting is not particularly limited, but is set to, for example, around 1400 ° C. Further, quenching is often performed by putting the melt in cold water or flowing it on a cold belt. The glass is pulverized by a ball mill, a vibration mill, a planetary mill, a bead mill, or the like until the desired particle size is reached.

The softening point is a measure that affects the fluidity of glass during firing. In the present invention, glass powder having a softening point equal to or lower than the temperature of the firing step can be used.

The softening point is that the temperature of the glass is raised at 10 ° C./min in the air by differential thermal analysis (TG-DTA) and heated, and the difference in the differential heat curve on the lowest temperature side of the obtained differential thermal curve is reduced. It is the temperature of the peak at which the next differential thermal curve on the higher temperature side than the developed temperature decreases.

The cumulative volume particle size D ₅₀ (median diameter) of the inorganic oxide powder is preferably 5 μm or less, and more preferably 3 μm or less. If the D50 of the inorganic oxide powder exceeds 5 μm, the effective area of the electrode may decrease due to the inorganic oxide present on the surface of the obtained electrode.

In the application of MLCC, it is desirable to use barium titanate powder as the inorganic oxide powder, and the average particle size (specific surface area average particle size) obtained from the specific surface area measured by the BET method is 0.01 μm or more. It is desirable that it is 0.2 μm or less. Thus, the inorganic oxide powder is too small, in which case the measurement of the D ₅₀ is difficult, it is also possible to evaluate an average particle diameter of the specific surface area thereof. The specific surface area average particle size is calculated by the following formula.
Specific surface area average particle size = 6 / pS (p: specific gravity, S: specific surface area)

The content of the inorganic oxide powder is preferably 25 parts by mass or less with respect to 100 parts by mass of the metal powder. When the content of the inorganic oxide powder exceeds 25 parts by weight, for example, the thickness of the dielectric layer expands due to the sintering of the inorganic oxide in the internal electrode and the ceramic particles in the dielectric layer, and the composition shifts. Since it occurs, it may adversely affect the electrical characteristics such as a decrease in the dielectric constant.

When a green sheet is used as a base material and the inorganic oxide powder is selected from aluminum oxide powder, zinc oxide powder, titanium oxide powder, murite powder, barium titanate powder, and lead zirconate titanate powder. The content of the inorganic oxide powder is preferably 3 parts by mass or more and 25 parts by mass or less, and more preferably 5 parts by mass or more and 15 parts by mass or less with respect to 100 parts by weight of the metal powder. In this case, if the content of the inorganic oxide powder is less than 3 parts by weight, for example, the sintering of the metal powder cannot be controlled, the mismatch between the sintering shrinkage behavior of the electrode precursor and the green sheet becomes remarkable, and further, the electrode Sintering of the precursor starts from a low temperature, and the difference in sintering temperature between the electrode precursor and the green sheet becomes large, so that firing cracks occur.

When a green sheet is not used as the base material and the inorganic oxide powder is a silicic acid-based glass powder, the content of the silicic acid-based glass powder is 0.5 parts by mass or more with respect to 100 parts by mass of the metal powder. It is desirable that it is less than a part by mass. If the content of the silicic acid-based glass powder exceeds 5% by mass, the glass component may cover a part of the electrode surface obtained after firing.

(1-3) Plasma Gas In the present invention, the metal powder-containing plasma gas for forming the electrode precursor can be formed only by atmospheric pressure plasma treatment under limited conditions.

Plasma treatment is a widely known technique, but the atmospheric pressure plasma polymerization treatment of the present invention is characterized in that a chemical reaction that does not normally proceed is allowed to proceed under atmospheric pressure by activating reaction particles by the atmospheric pressure plasma. Has. Atmospheric pressure plasma is suitable for continuous processing, so that it is highly productive, and because it does not require a vacuum device, the processing cost is low, and it can be carried out with a simple device configuration.

However, in the conventionally known atmospheric pressure plasma CVD method, after supplying the reaction gas, the carrier gas, and the reaction particles into the apparatus, the reaction gas is turned into plasma and the reaction particles are activated in the reaction region. It is common to do it at the same time.

On the other hand, in the atmospheric pressure plasma treatment of the present invention, the reaction gas is sufficiently plasma-generated in advance, and then metal particles are introduced into the plasma-generated reaction gas region, more preferably the reaction gas is plasma-generated. It differs from the conventional method in that metal particles are introduced in a region different from the region where the above is performed. In this way, since the metal particles are not introduced during the plasma conversion of the reaction gas, it is possible to prevent an emergency stop of the atmospheric pressure plasma processing device due to abnormal discharge by the metal particles during the plasma conversion, and the productivity is improved. In addition, cleaning and maintenance of atmospheric pressure plasma processing equipment can be facilitated.

Examples of the discharge method used for atmospheric pressure plasma include corona discharge, dielectric barrier discharge, RF discharge, microwave discharge, arc discharge, and the like, but in the present invention, any of them can be applied without particular limitation. Is. Therefore, as the device used for plasma conversion, a known plasma generator can be used without particular limitation as long as the reaction gas can be converted into plasma under atmospheric pressure. .. In the present invention, the atmospheric pressure includes the atmospheric pressure (1013.25 hPa) and the atmospheric pressure in the vicinity thereof, and also includes the atmospheric pressure within the range of the change of the normal atmospheric pressure.

In the conventional plasma treatment, it is common to use an inert gas such as argon (Ar) or helium (He) as the plasma gas. In the atmospheric pressure plasma treatment of the present invention, nitrogen (N ₂ ), oxygen (O ₂ ), and air can be used as the plasma gas (ionizing gas) in addition to argon and helium. These carrier gases may be used alone or in combination of two or more at a predetermined ratio. That is, it is possible to use a mixed gas of nitrogen and oxygen, which usually contains the atmosphere. Since nitrogen, oxygen, and air are inexpensive and easy to handle, not only productivity can be improved, but also workability can be improved. Of these gases, using nitrogen as the plasma gas is excellent in terms of the effect of fixing the metal powder to the substrate and economic efficiency.

In the case of generating nitrogen plasma, the nitrogen content in the plasma gas is preferably 30% by volume or more and 100% by volume or less.

(1-4) Carrier gas The carrier gas is not particularly limited as long as it can carry metal powder and inorganic oxide powder. Argon, helium, and nitrogen can be used. These carrier gases may be used alone or in combination of two or more at a predetermined ratio. From the viewpoint of production cost, it is preferable to use nitrogen.

(1-5) Plasmaization conditions The conditions for converting a reaction gas such as nitrogen gas into plasma to obtain plasma gas should be appropriately selected depending on the performance of the equipment used, the target film thickness, and the like. From the viewpoint of efficiently activating the metal powder of the present invention and appropriately adhering to the substrate, it is preferable to set the generator output voltage to 150 V or more and 350 V or less, and more preferably 200 V or more and 330 V or less. .. When the generator output voltage is less than 150 V, the nitrogen gas cannot be sufficiently plasma-generated, so that the surface of the metal powder may not be sufficiently activated. If the generator output voltage exceeds 350V, the problem of equipment damage may occur.

The method of mixing the metal powder in the plasma gas is not particularly limited, and the metal powder may be introduced into the plasma gas plasmalized in atmospheric pressure with a carrier gas, and the metal powder-containing plasma is subjected to such processing. You can get gas.

When the metal powder introduced into the plasma gas comes into contact with the plasma gas, a reaction that activates it instantly proceeds.

(2) Electrode precursor forming step In the electrode precursor forming step, a metal powder-containing plasma gas is sprayed on the surface of the base material to form an electrode precursor on the surface of the base material, and the base material with the electrode precursor is formed. This is the obtaining step (S2).

(2-1) Base material As the base material, a ceramic substrate such as an alumina substrate, a silicon nitride substrate, or an aluminum nitride substrate, a soda lime glass substrate, a glass ceramic substrate, and a green sheet can be used. As the green sheet, a ceramic green sheet containing alumina, barium titanate, or the like, or a green sheet made of a mixture of ceramic and glass such as alumina or zirconia can be used. The green sheet, which is a dielectric material containing barium titanate as a main component, is mainly used in the production of MLCC. Green sheets made of a mixture of ceramic and glass such as alumina and zirconia are mainly used in the production of LTCC substrates.

A green sheet containing barium titanate powder for MLCC as a main component is obtained by applying a mixture of barium titanate powder, a solvent and a polybutyral resin, which is a binder resin, to the surface of a base film by a roll coater method or the like and drying. Is formed. The thickness of the green sheet is 5 μm or less. The cumulative volume particle size D ₅₀ (median diameter) of the barium titanate powder is preferably 1.0 μm or less. When the barium titanate powder is composed of finer particles, the particle size can be evaluated by the average particle size of the specific surface area measured by the BET method.

A green sheet consisting of a mixture of ceramic and glass for LTCC substrates is prepared by applying a mixture of ceramic powder, glass powder, solvent, and binder resin, polybutyral resin or acrylic resin, to the surface of the base film by a roll coater method or the like. , Formed by drying. The thickness of the green sheet is 1 mm or less. The cumulative volume particle size D ₅₀ (median diameter) of the ceramic powder is preferably 0.5 μm or more and 1.0 μm or less, and the cumulative volume particle size D ₅₀ (median diameter) of the glass powder is preferably 5 μm or less. Further, as the glass powder, silicic acid-based glass powder can be used.

(2-2) Nozzle distance and nozzle movement speed The film thickness of the electrode precursor is appropriately set according to the application, and the film thickness of this electrode precursor depends on the condition setting of the atmospheric pressure plasma processing device to be used. It can be adjusted as appropriate.

For example, when an atmospheric pressure plasma polymerization processing apparatus (plasma polymer lab system PAD-1 type) manufactured by Plasmatreat is used as the atmospheric pressure plasma processing apparatus, the nozzle distance is preferably 5 mm or more and 30 mm or less, more preferably. Is set to 7 mm or more and 25 mm or less. The nozzle moving speed can be appropriately determined according to the film thickness of the electrode precursor.

(2-3) Pattern formation of electrode precursor A known metal mask or the like can be used for pattern formation of the electrode precursor. Use a metal mask having openings according to the location where the pattern of the electrode precursor is desired to be formed.

FIG. 3 is an example of a pattern in which the electrode precursor 22 is arranged on the surface of the green sheet 21 when manufacturing the MLCC. In MLCC, an electrode precursor serving as an internal electrode for forming a plurality of MLCCs is formed on one green sheet.

(3) Laminating Step In the laminating step, in the case of manufacturing a laminated electronic component by applying the electrode manufacturing method of the present invention and using a green sheet as a base material, after the electrode precursor forming step and before the firing step. This is a step (S3) of laminating base materials with electrode precursors and crimping the laminated bodies after laminating.

As the crimping means, a rigid body press, a hydrostatic pressure press, or the like can be used. As the conditions for the hydrostatic pressure press, it is preferable to set the temperature at the time of pressing to be 50 ° C. or higher and 80 ° C. or lower, the press pressure to be 50 MPa or higher and 125 MPa or lower, and the press time to be 300 seconds or longer and 600 seconds or lower. ..

In the case of MLCC, an electrode precursor serving as an internal electrode for forming a plurality of MLCCs is formed on one green sheet. After being crimped, it is cut into a predetermined shape and size by a guillotine or dicing method and individualized to obtain a laminated chip having a predetermined size.

(6) Firing Step The firing step is a step (S4) of firing a base material with an electrode precursor to form an electrode on the surface of the base material. In the manufacture of laminated electronic components, a step of firing a laminated base material with an electrode precursor, more specifically, a laminated body chip to form an electrode on the surface of the base material to obtain a laminated electronic component. be.

In the firing step, conditions can be appropriately selected depending on the metal powder and the base material.

When a glass substrate is used as the base material, it is fired at a temperature equal to or lower than the glass transition point of the glass substrate. Specifically, the temperature is 650 ° C. or lower. In this case, the metal powder includes silver powder, palladium powder, mixed powder of silver powder and palladium powder, silver-palladium alloy powder, copper powder, copper alloy powder, and aluminum powder. , Aluminum alloy powder is used. Of these, when copper powder, copper alloy powder, aluminum powder, and aluminum alloy powder are used, it is desirable that the atmosphere of the firing step be an inert atmosphere such as nitrogen.

When a ceramic substrate is used as the base material, the firing temperature is determined by the metal powder. In the case of gold powder, silver powder, palladium powder, mixed powder of silver powder and palladium powder, silver-palladium alloy powder, copper powder, and copper alloy powder, it can be fired at a temperature of 1000 ° C. or lower.

When a green sheet is used as the base material, the firing temperature is determined by the firing conditions of the green sheet. Therefore, it is preferable to set the firing temperature to 900 ° C. or higher and 1300 ° C. or lower. In the case of producing MLCC, when palladium powder is used as the metal powder constituting the electrode precursor, it is in an atmospheric atmosphere, and when nickel powder is used, it is in a nitrogen atmosphere or 5% by volume or less in nitrogen. It is preferable to bake in a reducing atmosphere to which hydrogen is added.

After the firing process, it is completed as an electronic component or a laminated electronic component by performing necessary processing on the electronic component such as attachment of terminal electrodes.

Hereinafter, examples of the present invention will be described in more detail with reference to the production of MLCC as an example, but the present invention is not limited to the following examples.

[Example 1]
(Metal powder-containing plasma gas forming step: S1)
An atmospheric pressure plasma polymerization treatment apparatus (PAD-1 type manufactured by Plasma Treat Co., Ltd.) was used. As the metal powder, the volume cumulative particle size _{D 50} was used spherical nickel powder is 0.2 [mu] m (200 nm). As the inorganic oxide powder, barium titanate powder having a specific surface area average particle diameter of 0.04 μm (40 nm) was used. The ratio of the nickel powder to the barium titanate powder was set to 15 parts by mass of the barium titanate powder with respect to 100 parts by mass of the nickel powder.

Nitrogen gas was used as both the plasma gas and the carrier gas. The conditions for plasma conversion of plasma gas were as follows.

<Plasma conversion conditions>
・ Transmission frequency of plasma generator: 21kHz
・ Output voltage of generator: 280V
-Pressure: Atmospheric pressure (1013.25 hPa)

Nitrogen gas is turned into plasma by an atmospheric pressure plasma processing device to obtain nitrogen plasma gas, and nitrogen plasma gas is introduced into a part different from the plasma gas generating part in the device, and the nitrogen plasma gas is mixed with the carrier gas. Nickel powder and barium titanate powder were introduced to form a metal powder-containing plasma gas.

(Electrode precursor forming step: S2)
A barium titanate green sheet having a thickness of 2 μm was used as a base material. Since the pattern of the electrode precursor as shown in FIG. 3 is formed on the surface of the green sheet, the size of the electrode precursor is suitable for 3216 size MLCC (length 3.2 mm, width 1.6 mm). A metal mask configured as described above was placed. A green sheet on which a metal mask was placed was installed in advance in the apparatus.

The distance between the spray nozzle for spraying the metal powder-containing plasma gas and the green sheet was set to 10 mm, and the metal powder-containing plasma gas was sprayed. As a result, the activated nickel powder and barium titanate powder introduced into the plasma gas adhere to the portion of the surface of the green sheet that is not masked by the metal mask, and an electrode precursor having a thickness of 2 μm is formed. Formed.

Using an atmospheric pressure plasma processing apparatus, 300 base materials (green sheets) with an electrode precursor on which such an electrode precursor was formed were produced. The occurrence of breakage or tearing of the base material (green sheet) with an electrode precursor was evaluated as a primary defect. Specifically, the electrode precursor of the base material with the electrode precursor was touched with tweezers, and the presence or absence of peeling of the electrode precursor was confirmed. As a result, the incidence of primary defects was 0%.

(Laminating process: S3)
Ten base materials (green sheets) with an electrode precursor and one green sheet on which no electrode precursor was formed were laminated. At the time of laminating, the base film of each green sheet was peeled off. Further, the orientation of the base material (green sheet) with the electrode precursor was adjusted so that each of the laminated layers had the same arrangement of the internal electrodes as the cross section of the MLCC in FIG. After laminating, each layer was pressure-bonded by holding at a pressure of 100 MPa at a temperature of 60 ° C. for 300 seconds by a hydrostatic press. After crimping, the chips were cut into 3216 size chips by dicing.

(Baking step: S4)
Thirty cut chips were fired in an electric furnace. As the debinder in the firing step, a primary debinder step of holding at a temperature of 280 ° C. for 6 hours in an atmospheric atmosphere and a secondary debinder holding at a temperature of 700 ° C. for 2 hours in a nitrogen atmosphere after the completion of the primary debindering step. A debinder step was performed.

After the secondary debinder, the maximum firing temperature was 1200 ° C., and the firing atmosphere was maintained as a mixed atmosphere of nitrogen and hydrogen for 1 hour for firing, and then the temperature was lowered to room temperature to obtain MLCC.

The obtained MLCC was observed by SEM in cross section, and the final defect rate was confirmed from the presence or absence of cracks. As a result, the final defective rate was 0%.

[Example 2]
The nickel powder used in Example 1 was introduced together with the carrier gas into the nitrogen plasma gas formed under the same conditions using the same atmospheric pressure plasma polymerization treatment apparatus as in Example 1 to form a metal powder-containing plasma gas. As the base material, 10 alumina substrates 1 in (25.4 mm) square and 1 mm thick were used, and an electrode precursor was formed on the entire surface of one surface of the base material. The electrode precursor of the base material with the electrode precursor was touched with tweezers, and the presence or absence of peeling of the electrode precursor was confirmed. As a result, the incidence of primary defects was 0%.

It was fired under the same conditions as the firing step of Example 1 to form a nickel electrode film on the surface of the alumina substrate. In Example 2, debinder is not required, but the firing was performed under the same conditions as in Example 1 due to the setting of the firing furnace. No defects such as peeling of the electrode from the base material and damage to the base material were found.

As described above, in the manufacturing process of the electrode and the laminated electronic component of the present invention, the electrode core formed by spraying the metal powder activated by the atmospheric pressure plasma does not peel off from the base material, and the base is formed. It was confirmed that no damage to the material was observed. In addition, no defects such as cracks were confirmed in the MLCC obtained in the firing step.

11 Porcelain Dielectric 12 Internal Electrode 13 Terminal Electrode 21 Green Sheet 22 Electrode Precursor

Claims (8)

A step of supplying a carrier gas and a metal powder into a plasma gas that has been pre-plasma-ized under atmospheric pressure and mixing them to form a plasma gas containing the metal powder.
A step of spraying the metal powder-containing plasma gas onto the surface of the base material to form an electrode precursor on the surface of the base material to obtain a base material with the electrode precursor, and
A method for manufacturing an electrode, comprising a step of firing the base material with an electrode precursor to form an electrode on the surface of the base material. Claim 1 uses, as the metal powder, at least one selected from gold powder, silver powder, palladium powder, copper powder, nickel powder, aluminum powder, silver-palladium alloy powder, copper alloy powder, and aluminum alloy powder. The method for manufacturing an electrode according to. The method for producing an electrode according to claim 1 or 2, wherein the metal powder-containing plasma gas contains an inorganic oxide powder. As the inorganic oxide powder, at least one selected from aluminum oxide powder, zinc oxide powder, titanium oxide powder, murite powder, barium titanate powder, lead zirconate titanate powder, and silicic acid-based glass powder is used. Item 3. The method for manufacturing an electrode according to Item 3. The method for producing an electrode according to any one of claims 1 to 4, wherein the plasma gas is obtained by converting at least one selected from argon, helium, nitrogen, oxygen, and air into plasma. The method for producing an electrode according to any one of claims 1 to 5, wherein at least one selected from argon, helium, and nitrogen is used as the carrier gas. The method for producing an electrode according to any one of claims 1 to 6, wherein a ceramic green sheet is used as the base material. After the step of obtaining the base material with the electrode precursor using the method for producing an electrode according to claim 7, the base material with the electrode precursor is laminated, and then the base material with the electrode precursor is fired. A method for manufacturing a laminated electronic component, wherein a laminated electronic component is obtained by performing a step of forming an electrode on the surface of the base material.

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