JP2002043163A - Laminated ceramic electronic component and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further prevent structural defects from being produced in a laminated ceramic capacitor, formed by baking a raw laminate in which a ceramic green layer for absorbing a step is formed on a ceramic green sheet, so as to substantially eliminate a step caused by an internal electrode. SOLUTION: Before a composite structure 6, formed by the internal electrode 1 and the ceramic green layer 5 for absorbing a step is laminated on the ceramic green sheet 2, the composite structure 6 is rolled by calendar rolls 7, 8 to thereby make its surface smooth.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer ceramic electronic component and a method for manufacturing the same.
Multilayer ceramic electronic component having a step absorbing ceramic layer formed with a negative pattern of an internal circuit element film pattern to absorb a step caused by the thickness of an internal circuit element film formed between ceramic layers, and a method of manufacturing the same It is about.

[0002]

2. Description of the Related Art When manufacturing a multilayer ceramic electronic component such as a multilayer ceramic capacitor, a plurality of ceramic green sheets are prepared and these ceramic green sheets are stacked. Depending on the function of the multilayer ceramic electronic component to be obtained, internal circuits such as conductor films and resistor films for forming capacitors, resistors, inductors, varistors, filters, etc., on specific ceramic green sheets An element film is formed.

In recent years, electronic devices such as mobile communication devices have been reduced in size and weight. In such electronic devices, for example, when a multilayer ceramic electronic component is used as a circuit element, such electronic devices have been described. There has been a strong demand for smaller, thinner and lighter ceramic electronic components. For example, in the case of a multilayer ceramic capacitor, there is an increasing demand for a reduction in size or thickness and an increase in capacity.

In order to manufacture a multilayer ceramic capacitor, typically, a ceramic slurry is prepared by mixing a dielectric ceramic powder, an organic binder, a plasticizer, and an organic or aqueous solvent, and the ceramic slurry is peeled off. By applying a doctor blade method or the like on a support such as a polyester film coated with a silicone resin or the like as an agent to form a sheet having a thickness of several μm, for example, the ceramic green A sheet is made and then the ceramic green sheet is dried.

[0005] Next, a conductive paste is applied on the main surface of the above-described ceramic green sheet in a plurality of patterns spaced apart from each other by screen printing.
By drying this, an internal electrode as an internal circuit element film is formed on the ceramic green sheet. FIG. 8 is a plan view showing a part of the ceramic green sheet 2 on which the internal electrodes 1 are formed at a plurality of locations as described above.

Next, after the ceramic green sheets 2 are peeled off from the support and cut into appropriate sizes, a predetermined number of the sheets are stacked as shown in FIG. By stacking a predetermined number of ceramic green sheets on which no internal electrodes are formed, a green laminate 3 is manufactured.

After the green laminate 3 is pressed in the laminating direction, as shown in FIG. 9, it is cut into a size to be a laminated chip 4 for each laminated ceramic capacitor. After passing through the binder step, it is subjected to a firing step, and finally an external electrode is formed, whereby a multilayer ceramic capacitor is completed.

In such a multilayer ceramic capacitor, in order to satisfy the demand for miniaturization, thinning, and large capacity, it is necessary to increase the number of stacked ceramic green sheets 2 and internal electrodes 1 and to reduce the thickness of the ceramic green sheets 2. It is necessary to stratify.

However, as the above-described multi-layering and thinning progress, the accumulation of the thicknesses of the internal electrode 1 results in the gap between the portion where the internal electrode 1 is located and the portion where it is not, or The difference in thickness between the portion where the electrodes 1 are arranged in a relatively large number in the stacking direction and the portion where the electrode 1 is not so large becomes more conspicuous. For example, as shown in FIG. With regard to, deformation occurs such that one of the main surfaces becomes convex.

If the laminated chip 4 is deformed as shown in FIG. 9, in a portion where the internal electrodes 1 are not located or in a portion where only a relatively small number of the internal electrodes 1 are arranged in the laminating direction, Since a relatively large strain is caused during the pressing process and the adhesion between the ceramic green sheets 2 is poor, structural defects such as delamination and minute cracks are caused by internal stress caused during firing. Likely to happen.

The deformation of the laminated chip 4 as shown in FIG. 9 results in the internal electrode 1 being undesirably deformed.
This may cause a short-circuit failure.

Such inconvenience causes a reduction in the reliability of the multilayer ceramic capacitor.

In order to solve the above-described problem, for example, as shown in FIG. 2, a ceramic green layer 5 for absorbing a step is formed in a region on the ceramic green sheet 2 where the internal electrode 1 is not formed. The step-absorbing ceramic green layer 5 can substantially eliminate the step due to the thickness of the internal electrode 1 on the ceramic green sheet 2 as disclosed in, for example, JP-A-56-94719 and JP-A-3-74820. And JP-A-9-106925.

As described above, by forming the step absorbing ceramic green layer 5, as shown in FIG. 1, when the raw laminate 3a is manufactured, the portion where the internal electrode 1 is located is the same as the portion where the internal electrode 1 is located. And the thickness difference between the portion where the internal electrodes 1 are arranged in a relatively large number in the stacking direction and the portion where the internal electrode 1 is not so much does not substantially occur.
As shown in FIG. 3, in the obtained laminated body chip 4a, undesired deformation as shown in FIG. 9 hardly occurs.

As a result, problems such as the above-described structural defects such as delamination and minute cracks and short-circuit failure due to deformation of the internal electrode 1 can be suppressed, and the reliability of the obtained multilayer ceramic capacitor can be improved. Can be.

[0016]

In the method described with reference to FIGS. 1 to 3 described above, since the thickness of the internal electrode 1 is 2 μm or less, the thickness of the step absorbing ceramic green layer 5 is also However, when the dispersibility of the ceramic paste used to form the step-absorbing ceramic green layer 5 is poor, the step-absorbing ceramic green layer 5 cannot be formed with high accuracy, for example, by printing. Not only that, the smoothness of the surface of the step absorbing ceramic green layer 5 may be deteriorated.

In order to improve the dispersibility of the ceramic paste, it is conceivable to lower the viscosity of the ceramic paste and increase the efficiency in the dispersion treatment. Must increase the amount of solvent added in the ceramic paste. However, when the amount of the solvent added is increased, the time required for removing the solvent after the dispersion treatment becomes longer, which causes a decrease in productivity of the multilayer ceramic electronic component.

A similar problem is encountered in other multilayer ceramic electronic components such as multilayer inductors other than multilayer ceramic capacitors.

An object of the present invention is to provide a method for manufacturing a multilayer ceramic electronic component and a multilayer ceramic electronic component obtained by the manufacturing method, which can solve the above-described problems. .

[0020]

The present invention is first directed to a method for manufacturing a multilayer ceramic electronic component. In this manufacturing method, basically, the following steps are performed.

First, a ceramic slurry, a conductive paste, and a ceramic paste are prepared.

Next, the ceramic green sheet obtained by molding the ceramic slurry and the conductive paste are partially applied to the main surface of the ceramic green sheet so as to provide a step due to the thickness thereof. Formed on the main surface of the ceramic green sheet and applying a ceramic paste to a region where the internal circuit element film is not formed so as to substantially eliminate a step due to the thickness of the internal circuit element film. A plurality of composite structures including the step-absorbing ceramic green layer are produced.

Next, a green laminate is produced by stacking the plurality of composite structures.

Then, the green laminate is fired.

In the method of manufacturing a multilayer ceramic electronic component having such basic steps, in order to solve the above-mentioned technical problems, before stacking a plurality of composite structures, the surface of each composite structure is rolled. The method further comprises a step of performing smoothing.

The above-mentioned rolling is performed, for example, by applying a calender roll method to each composite structure, or by applying a method of pressing each composite structure between two metal plates. Or you can.

In the present invention, the above-mentioned ceramic paste comprises at least a primary dispersion step of subjecting a primary mixture containing at least a ceramic powder and a first organic solvent to a dispersion treatment; A secondary dispersion step of dispersing the secondary mixture to which the binder has been added;
After the step of including the second organic solvent having a higher boiling point than the organic solvent in the primary mixture and / or the secondary mixture, and after the secondary dispersion step, the secondary mixture is subjected to heat treatment to thereby form the first organic solvent.
And a removing step of selectively removing the organic solvent.

Further, in the present invention, the first ceramic powder preferably has substantially the same composition as the second ceramic powder.

In a specific embodiment of the present invention, the first and second ceramic powders contained in the ceramic slurry and the ceramic paste are both dielectric ceramic powders. In this case, when the internal circuit element films are the internal electrodes arranged so as to form a capacitance therebetween, a multilayer ceramic capacitor can be manufactured.

In another specific embodiment of the present invention, the ceramic powder contained in each of the ceramic slurry and the ceramic paste is a magnetic ceramic powder. In this case, the internal circuit element film is
When the coil conductor film extends in a coil shape, a laminated inductor can be manufactured.

The present invention is also directed to a multilayer ceramic electronic component obtained by the above-described manufacturing method.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described.
A method for manufacturing a multilayer ceramic capacitor will be described.
The method for manufacturing the multilayer ceramic capacitor according to this embodiment can be described with reference to FIGS. 1 to 3 described above.

In carrying out this embodiment, a ceramic slurry for the ceramic green sheet 2, a conductive paste for the internal electrode 1, and a ceramic paste for the step-absorbing ceramic green layer 5 are prepared.

In order to obtain the ceramic green sheet 2 from the above-mentioned ceramic slurry, the ceramic slurry is applied to a doctor blade, for example, on a support (not shown) such as a polyester film coated with a silicone resin or the like as a release agent. It is formed by a method or the like and then dried. Ceramic green sheet 2
Are, for example, several μm after drying.

On the main surface of the ceramic green sheet 2, the internal electrodes 1 are formed to have a thickness of, for example, about 1 μm after drying so as to be distributed at a plurality of locations. The internal electrode 1 is formed, for example, by applying a conductive paste by screen printing or the like and drying the conductive paste. Each of the internal electrodes 1 has a predetermined thickness. Therefore, a step is generated on the ceramic green sheet 2 due to the thickness.

Next, in order to substantially eliminate the step due to the thickness of the internal electrode 1, a step-absorbing ceramic is provided on the main surface of the ceramic green sheet 2 where the internal electrode 1 is not formed. A green layer 5 is formed. The step absorbing ceramic green layer 5 includes the internal electrode 1.
Is formed by applying the above-mentioned ceramic paste by screen printing or the like with the negative pattern described above, and then dried.

In the above description, the step absorbing ceramic green layer 5 was formed after the internal electrode 1 was formed.
Conversely, the internal electrode 1 may be formed after the step absorption ceramic green layer 5 is formed.

As described above, the composite structure 6 as shown in FIG. 2 in which the internal electrode 1 and the step absorbing ceramic green layer 5 are formed on the ceramic green sheet 2,
After peeling from the support, to smooth its surface,
It is subjected to a rolling process.

FIG. 4 shows a state where the rolling process is being performed on the composite structure 6. In the illustrated rolling process, a calender roll method in which the composite structure 6 is passed between a pair of calender rolls 7 and 8 is applied. The material and size of the calender rolls 7 and 8 to be used are not particularly limited, but it is preferable to use, for example, a metal roll made of stainless steel, whose surface is polished and subjected to chrome plating. Although not shown, the calender rolls 7 and 8 are preferably provided with a heating means.

Instead of the calender roll method shown in FIG. 4, a method in which the composite structure 6 is pressed between two metal plates and pressed may be applied. In this case, for example, a mirror-polished stainless steel metal plate is advantageously used, and it is preferable to press while applying heat by using a hot press machine or the like.

The rolling step may be repeated a plurality of times as necessary. Further, the rolling process is performed in the composite structure 6.
Is carried out before peeling from the support, and after the rolling process,
The composite structure 6 may be separated from the support.

As described above, a plurality of composite structures 6 whose surfaces have been smoothed are prepared, and these composite structures 6 are cut into a suitable size, stacked by a predetermined number, and furthermore, vertically. By stacking the ceramic green sheets on which the internal electrodes and the step absorbing ceramic green layer are not formed, a raw laminate 3a partially shown in FIG. 1 is produced.

After the green laminate 3a is pressed in the laminating direction, as shown in FIG. 3, the green laminate 3a is cut into a size to become a laminate chip 4a for each multilayer ceramic capacitor. After passing through the binder step, it is subjected to a firing step, and finally an external electrode is formed, whereby a multilayer capacitor is completed.

As described above, by forming the step absorbing ceramic green layer 5, as shown in FIG. 1, a portion where the internal electrode 1 is located and a portion where the internal electrode 1 is not located in the raw laminate 3 a. A difference in thickness between a portion where the internal electrodes 1 are arranged in a relatively large number in the stacking direction and a portion where the internal electrodes 1 are not so arranged substantially does not occur.

Before the composite structures 6 are stacked, their surfaces are smoothed by rolling, for example, as shown in FIG. Therefore, the unevenness of the surface of the composite structure 6 is eliminated, and the thickness variation is reduced.

From these facts, as shown in FIG. 3, undesired deformation hardly occurs in the multilayer chip 4a, and in the obtained multilayer ceramic capacitor, structural defects such as delamination and minute cracks are reduced. Problems such as short-circuit failure can be suppressed.

The conductive paste used to form the internal electrode 1 contains a conductive powder, a solvent, and a resin component such as an organic binder. As the solvent contained, it is preferable to use a solvent having a boiling point of 150 ° C. or higher in consideration of screen printability.
It is more preferable to use one having a boiling point of about 0 to 250 ° C. If the temperature is lower than 150 ° C., the ceramic paste or the conductive paste is apt to dry, so that the mesh of the printed pattern is liable to be clogged.
If the temperature exceeds 250 ° C., the printed coating film is difficult to dry, and it takes a long time for drying.

When the solvent contained in the ceramic slurry, ceramic paste and conductive paste is an organic solvent, examples of such an organic solvent include ketones such as methyl ethyl ketone, methyl isobutyl ketone, acetone, toluene, benzene and xylene. , Hydrocarbons such as normal hexane, alcohols such as methanol, ethanol, isopropanol, butanol and amyl alcohol, esters such as ethyl acetate, butyl acetate and isobutyl acetate, diisopropyl ketone, ethyl cellosolve, butyl cellosolve and cellosolve. Acetate, methylcellosolve acetate, butyl carbitol, cyclohexanol, pine oil, dihydroterpineol, isophorone, terpineol, cipropylene glycol, dimethyl phthalate, etc. Emissions, esters, hydrocarbons,
Examples include alcohols, chlorinated hydrocarbons such as methylene chloride, and mixtures thereof.

Further, as the organic binder,
At room temperature, those soluble in the above-mentioned solvents are preferred. Examples of such organic binders include polyacetals such as polyvinyl butyral and polybutyl butyral, modified celluloses such as poly (meth) acrylates, ethyl cellulose, alkyds, vinylidenes, polyethers, and epoxy resins. , Urethane resins, polyamide resins, polyimide resins, polyamide imide resins, polyester resins, polysulfone resins, liquid crystal polymers, polyimidazole resins, polyoxazoline resins, and the like.

The polyvinyl butyral exemplified above as the organic binder is obtained by condensation of polyvinyl alcohol and butyraldehyde, and is a low polymer product having an acetyl group of 6 mol% or less and a butyral group of 62 to 82 mol%. , Medium polymerization products and high polymerization products. The polyvinyl butyral used as the organic binder in the ceramic paste is preferably a medium polymerized product having a butyral group of about 65 mol% from the balance between the dissolution viscosity in an organic solvent and the toughness of the dried coating film.

In particular, in producing a ceramic paste for the step absorbing ceramic green layer 5, it is preferable to employ the following method.

That is, as the organic solvent, a first organic solvent having a relatively high boiling point and a second organic solvent having a relatively low boiling point are used, and at least the second ceramic powder and the second organic solvent are contained. A primary dispersion step for dispersing the secondary mixture and a secondary dispersion step for dispersing a secondary mixture obtained by adding at least an organic binder to the primary mixture after the primary dispersion step are performed. The first organic solvent is added at the stage of the primary dispersion process or the stage of the secondary dispersion process, or at both the stage of the primary dispersion process and the stage of the secondary dispersion process. Then, finally, after the secondary dispersion step, the second organic solvent is selectively removed by heat-treating the secondary mixture.

As described above, in the primary dispersion step, since the organic binder has not been added yet, the dispersion treatment can be performed under a low viscosity, and therefore, it is easy to enhance the dispersibility of the second ceramic powder. . In this primary dispersion step, the second
The air adsorbed on the surface of the ceramic powder is replaced with the second organic solvent, and the second ceramic powder can be sufficiently wetted with the second organic solvent. Can be sufficiently disintegrated.

In the secondary dispersion step, as described above,
The organic binder can be sufficiently and uniformly mixed while maintaining the high dispersibility of the second ceramic powder obtained in the primary dispersion step, and a further pulverizing effect of the second ceramic powder can be expected.

Also, since the removal of the second organic solvent is performed after the secondary dispersion step, the viscosity of the secondary mixture can be kept relatively low even at the stage of the secondary dispersion step. Accordingly, the dispersion efficiency can be kept relatively high, and the solubility of the organic binder added in the secondary dispersion step as described above can be increased.

The second organic solvent described above includes
Considering the relationship with the boiling point of the first organic solvent, for example, methyl ethyl ketone, methyl isobutyl ketone, acetone, toluene, benzene, methanol, ethanol, isopropanol, ethyl acetate, isobutyl acetate,
Butyl acetate, and mixtures thereof, can be used to advantage.

The first ceramic powder contained in the ceramic slurry for the ceramic green sheet 2 has substantially the same composition as the second ceramic powder contained in the ceramic paste for the step absorbing ceramic green layer 5. It is preferable to have. This is because the sinterability between the step absorbing ceramic green layer 5 and the ceramic green sheet 2 is matched.

Note that having substantially the same composition as described above means that the main components are the same. For example,
Even if minor components such as trace addition metal oxide and glass are different,
It can be said that they have substantially the same composition. Also,
If the ceramic powder contained in the ceramic green sheet 2 has a temperature characteristic of the capacitance that satisfies the B characteristic stipulated by the JIS standard and the X7R characteristic stipulated by the EIA standard, the step-absorbing ceramic green layer 5 is used. The ceramic powder contained in the ceramic paste may have different sub-components as long as they have the same main component and satisfy the B characteristics and the X7R characteristics.

In the ceramic slurry for the ceramic green sheet 2 and the ceramic paste for the ceramic green layer 5 for absorbing a level difference, a dispersant, a plasticizer, an antistatic agent, an antifoaming agent and the like may be added as necessary. May be done.

FIG. 5 is a view for explaining a method of manufacturing a laminated inductor according to another embodiment of the present invention. FIG. 6 is a perspective view showing the appearance of the laminated inductor manufactured by this method. FIG. 2 is an exploded perspective view showing elements constituting a raw laminate 13 prepared for obtaining a laminate chip 12 provided in 11.

The green laminate 13 includes a plurality of ceramic green sheets 14, 15, 16, 17,...
9 and these ceramic green sheets 14 to 19
Are obtained by laminating.

The ceramic green sheets 14 to 19 are
It is obtained by shaping a ceramic slurry containing a magnetic ceramic powder by a doctor blade method or the like and drying. Each thickness of the ceramic green sheets 14 to 19 is, for example, 10 to 30 μm after drying.

Among the ceramic green sheets 14 to 19, the ceramic green sheets 15 to 1 located in the middle
8, a coil conductor film extending in a coil shape and a step absorbing ceramic green layer are formed as described in detail below.

First, the coil conductor film 20 is formed on the ceramic green sheet 15. Coil conductor film 20
Is formed such that its first end reaches the edge of the ceramic green sheet 15. A via-hole conductor 21 is formed at the second end of the coil conductor film 20.

In order to form such a coil conductor film 20 and via-hole conductor 21, for example, a through-hole for via-hole conductor 21 is formed in ceramic green sheet 15 by a method such as laser or punching. And a conductive paste that becomes the via-hole conductor 21 is applied by screen printing or the like,
Drying is performed.

In order to substantially eliminate the above-mentioned step due to the thickness of the coil conductor film 20, a region where the coil conductor film 20 is not formed on the main surface of the ceramic green sheet 15 is provided. A ceramic green layer 22 is formed. Ceramic green layer for step absorption 2
2 is formed by applying the ceramic paste containing the magnetic ceramic powder, which is a feature of the present invention, by screen printing or the like, and drying the paste.

Next, on the ceramic green sheet 16, the coil conductor film 23, the via-hole conductor 24 and the step absorbing ceramic green layer 25 are formed in the same manner as described above. First of the coil conductor film 23
Is connected to the second end of the coil conductor film 20 via the via-hole conductor 21 described above. The via-hole conductor 24 is formed at the second end of the coil conductor film 23.

Next, on the ceramic green sheet 17, a coil conductor film 26, a via-hole conductor 27 and a step-absorbing ceramic green layer 28 are similarly formed. The first end of the coil conductor film 26 is connected to the second end of the coil conductor film 23 via the via-hole conductor 24 described above. The via-hole conductor 27 is formed of the coil conductor film 2.
6 formed at the second end.

The above-mentioned lamination of the ceramic green sheets 16 and 17 is repeated a plurality of times as necessary.

Next, a coil conductor film 29 and a step absorbing ceramic green layer 30 are formed on the ceramic green sheet 18. The first end of the coil conductor film 29 is connected to the second end of the coil conductor film 26 via the via-hole conductor 27 described above. Coil conductor film 29
Is formed such that its second end reaches the edge of the ceramic green sheet 18.

The above-mentioned coil conductor films 20, 23,
The thickness of each of 26 and 29 is, for example, about 30 μm after drying.

Such a ceramic green sheet 14
In the raw laminated body 13 obtained by laminating a plurality of composite structures each including-to 19, a plurality of coil conductor films 20, 23, 26 and 29 each extending in a coil shape are formed in the via-hole conductors 21, 24 and 27. , A plurality of turns of the coil conductor are formed as a whole.

Each of the plurality of composite structures including the ceramic green sheets 14 to 19 for obtaining the above-described green laminate 13 is rolled before stacking them, and the surface thereof is smoothed. For this rolling, the calender roll method shown in FIG. 4 as described above, the method of pressing between two metal plates, and the like are applied.

Next, the green laminate 13 is fired to obtain the multilayer chip 12 for the multilayer inductor 11 shown in FIG. Although the raw laminate 13 is shown in FIG. 5 as one for obtaining one laminated chip 12, it is produced for obtaining a plurality of laminated chips and cut. Thereby, a plurality of stacked chips may be taken out.

Next, as shown in FIG. 6, the opposite ends of the laminated chip 12 are provided with the above-described coil conductor film 2.
The external electrodes 30 and 31 are formed so as to be connected to the first end of the coil 0 and the second end of the coil conductor film 29, respectively, whereby the laminated inductor 11 is completed.

In the multilayer ceramic electronic component such as the multilayer ceramic capacitor described with reference to FIGS. 1 to 3 or the multilayer inductor 11 described with reference to FIGS. 5 and 6, the ceramic green sheet or the step absorbing ceramic is used. Typical ceramic powders contained in the green layer include oxide ceramic powders such as alumina, zirconia, magnesia, titanium oxide, barium titanate, lead zirconate titanate, and ferrite-manganese, silicon carbide, and silicon nitride. And non-oxide ceramic powder such as sialon. The average particle diameter of the powder is preferably 5 μm.
Hereinafter, more preferably, a 1 μm spherical or pulverized material is used.

When barium titanate having an alkali metal oxide content of 0.1% by weight or less as an impurity is used as a ceramic powder, the following metal oxide is added to the ceramic powder as a trace component. An article or a glass component may be contained.

As the metal oxide, terbium oxide, dysprosium oxide, holmium oxide, erbium oxide,
Examples include ytterbium oxide, manganese oxide, cobalt oxide, nickel oxide, and magnesium oxide.

The glass component is Li_Two− (S
iTi) O_Two-MO (where MO is Al_TwoO_ThreeOr
ZrO_Two), SiO_Two-TiO_Two-MO (however, MO
Is BaO, CaO, SrO, MgO, ZnO or Mn
O), Li_TwoOB_TwoO_Three-(SiTi) O_Two+ MO
(However, MO is Al_TwoO_ThreeOr ZrO_Two), B_TwoO
_Three-Al_TwoO_Three-MO (where MO is BaO, Ca
O, SrO or MgO), or SiO_TwoEtc.

In the multilayer ceramic capacitor described with reference to FIGS. 1 to 3 or the multilayer inductor 11 described with reference to FIGS.
Alternatively, as the conductive paste used for forming coil conductor films 20, 23, 26 and 29 and via hole conductors 21, 24 and 27, for example, the following can be used.

The conductive paste used in the multilayer ceramic capacitor has an average particle size of 0.02 μm.
３3 μm, preferably 0.05-0.5 μm,
Ag / Pd is 60% by weight / 40% by weight to 10% by weight / 9
0% by weight of a conductive powder made of an alloy, a nickel metal powder or a copper metal powder, and the like, 100 parts by weight of this powder and 2 to 20 parts by weight of an organic binder (preferably 5 to 1 part by weight).
0 parts by weight) and Ag, Au, Pt,
About 0.1 to 3 parts by weight (preferably 0.5 to 1 part by weight) of a metal resinate such as Ti, Si, Ni or Cu in terms of metal, and about 35 parts by weight of an organic solvent are rolled with three rolls. After kneading, a conductive paste obtained by further adding the same or another organic solvent and adjusting the viscosity can be used.

The metal powder used in the conductive paste can be produced by various methods. For example, a metal powder having an average particle diameter of 1 produced by a gas phase method can be used.
Those having a thickness of about 00 nm can also be used. When nickel metal powder or copper metal powder is used,
In the firing step, a reducing atmosphere is applied.

The conductive paste used in the laminated inductor 11 is such that Ag / Pd is 80% by weight / 20.
% By weight of a conductive powder composed of an alloy or Ag in an amount of 100% by weight to 100% by weight of an organic binder as in the case of the conductive paste for a multilayer ceramic capacitor described above. After kneading the sintering inhibitor and the organic solvent in the same ratio with three rolls, the same or another organic solvent is further added to adjust the viscosity, so that a conductive paste obtained can be used.

Hereinafter, the present invention will be described based on experimental examples.
This will be described more specifically.

[0085]

EXPERIMENTAL EXAMPLE 1 Experimental example 1 relates to a multilayer ceramic capacitor.

1. Preparation of Dielectric Ceramic Powder First, barium carbonate (BaCO ₃ ) and titanium oxide (TiO ₂ ) were weighed so as to have a molar ratio of 1: 1 and wet-mixed using a ball mill, followed by dehydration drying. Next, after calcining at a temperature of 1000 ° C. for 2 hours, the resultant was pulverized to obtain a dielectric ceramic powder.

2. Preparation of Ceramic Slurry and Preparation of Ceramic Green Sheet 100 parts by weight of dielectric ceramic powder previously prepared, 7 parts by weight of polyvinyl butyral having a medium polymerization degree and a high degree of butyralization, and DOP (dioctyl phthalate) 3 as a plasticizer
Parts by weight, 30 parts by weight of methyl ethyl ketone, 20 parts by weight of ethanol, and 20 parts by weight of toluene
Together with 600 parts by weight of a zirconia-made boulder, and placed in a ball mill, and wet-mixed for 20 hours to obtain a dielectric ceramic slurry.

Then, a doctor blade method was applied to this dielectric ceramic slurry to obtain a 3 μm thick ceramic slurry.
A dielectric ceramic green sheet (having a thickness of 2 μm after firing) was formed. Drying was performed at 80 ° C. for 5 minutes.

3. Preparation of conductive paste 100 parts by weight of metal powder of Ag / Pd = 30/70, 4 parts by weight of ethyl cellulose, 2 parts by weight of alkyd resin, and 3 parts by weight of Ag metal resinate (17.5% as Ag)
Parts by weight) and 35 parts by weight of butyl carbitol acetate were kneaded with a three-roll mill, and 35 parts by weight of terpineol was added to adjust the viscosity.

4. Preparation of Ceramic Paste for Ceramic Green Layer for Absorbing Step-Samples 1 and 2 (Example) and Sample 4 (Comparative Example)
-100 parts by weight of the previously prepared dielectric ceramic powder, 40 parts by weight of terpineol having a boiling point of 220 ° C, and 5 parts by weight of ethyl cellulose resin were mixed in an automatic mortar,
The mixture was sufficiently kneaded with this roll to obtain a dielectric ceramic paste.

-Sample 3 (Example)-100 parts by weight of the dielectric ceramic powder prepared above, 70 parts by weight of methyl ethyl ketone having a boiling point of 79.6 ° C., and a quaternary ammonium polyacrylate dispersant (weight average molecular weight: 1000) 0.5 part by weight and 600 parts by weight of a zirconia cobblestone having a diameter of 1 mm were charged into a ball mill, and wet-mixed for 16 hours as a primary dispersion step. Next, 10 parts by weight of terpineol having a boiling point of 220 ° C. and 5 parts by weight of ethylcellulose resin were added to the same pot, and the mixture was further mixed for 16 hours as a secondary dispersion step to obtain a ceramic slurry mixture.

Next, the above-mentioned ceramic slurry mixture was distilled under reduced pressure in an evaporator at 60 ° C. for 2 hours to completely remove methyl ethyl ketone to obtain a dielectric ceramic paste. Then, for viscosity adjustment, 10 to 20 parts by weight of terpineol was added and dispersed and adjusted by an automatic mortar.

[0093] 5. Preparation of Composite Structure In order to form internal electrodes on the main surface of the previously prepared dielectric ceramic green sheet, a conductive paste was screen-printed and dried at 80 ° C. for 10 minutes. The dimensions, shape and position of the internal electrodes were set so as to be compatible with the laminated chip obtained in a later step. Next, in order to form a step absorption ceramic green layer on the main surface of the dielectric ceramic green sheet, each dielectric ceramic paste according to Samples 1 to 4 was screen-printed,
Dry for 0 minutes. Each thickness of the internal electrode and the step absorbing ceramic green layer is 1.5 μm after drying.
(The thickness after firing was 0.8 μm).

6. Rolling of Composite Structure -Sample 1 (Example)-The composite structure obtained as described above was sandwiched between two mirror-polished stainless steel metal plates, and heated at 50 ° C.
, And pressed for 1 minute under a pressing condition of 50 kg / cm ² .

-Samples 2 and 3 (Examples)-The composite structure obtained as described above was lined with a carrier film made of polyethylene terephthalate as a support used in forming a dielectric ceramic green sheet. While in the state, a pair of mirror-polished stainless steel calender rolls are placed at a speed of 2 m / min.
I passed. At this time, the calender roll was heated to 80 ° C., and the interval between the calender rolls was set to a size obtained by adding 6 μm to the thickness of the carrier film.

-Sample 4 (Comparative Example)-The composite structure obtained as described above was not rolled.

7. Completion of Multilayer Ceramic Capacitor Next, as described above, 500 dielectric ceramic green sheets forming the internal electrodes and the step absorbing ceramic green layer, that is, 500 composite structures,
The laminate is stacked so as to be sandwiched between 20 dielectric ceramic green sheets to which no internal electrode or the like is provided, and a raw laminate is produced.
It was hot-pressed under a pressure of cm ² .

Next, the above-mentioned green laminate is cut with a cutting blade so as to have a size of 3.2 mm in length × 1.6 mm in width × 1.6 mm in thickness after sintering. I got a body chip.

Next, on the firing setter on which a small amount of zirconia powder was sprayed, the above-mentioned plurality of laminated chips were aligned, and the temperature was raised from room temperature to 250 ° C. over 24 hours to remove the organic binder. Next, the laminated chip was put into a firing furnace and fired at a maximum of 1300 ° C. for a profile of about 20 hours.

Next, the obtained sintered compact chip was placed in a barrel, and after polishing the end face, external electrodes were provided at both ends of the sintered compact to complete a multilayer ceramic capacitor as a sample.

8. Evaluation of Characteristics Various characteristics were evaluated for the composite structure and the multilayer ceramic capacitor according to each of Samples 1 to 4 described above.
The results are shown in Table 1.

[0102]

[Table 1]

The characteristics evaluation in Table 1 was performed as follows.

“Surface roughness”: The surface roughness Ra of the composite structures immediately before stacking, that is, the value obtained by averaging the absolute value of the deviation between the center line obtained by averaging the undulations and the roughness curve, is defined as the ratio It was determined from the measurement result by a contact type laser surface roughness meter.

“Thickness variation”: For the composite structure immediately before stacking, an arbitrary area having an area of 25 cm ² was selected.
The thickness at any nine locations in this region was measured with a micrometer, and the thickness variation σ _n-1 was calculated.

"Structural defect defect rate": When abnormalities were found in the appearance inspection of the sintered chip for the obtained multilayer ceramic capacitor and the inspection with an ultrasonic microscope, the internal structural defects were confirmed by polishing, (Number of sintered chips having structural defects) / (total number of sintered chips) was defined as the structural defect defect rate.

In Table 1, when the comparison is made between Samples 1 to 3 as the examples and Sample 4 as the comparative example, Samples 1 to 3 according to the Example are compared with Sample 4 as the comparative example. It can be seen that excellent results are shown in “surface roughness”, “thickness variation” and “structural defect defect rate”.

In particular, when comparing Samples 1 to 3 as examples, in order to obtain a dielectric ceramic paste for the step-absorbing ceramic green layer, a primary dispersion step and a secondary dispersion step were employed. According to Sample 3, in which the organic binder was added in the secondary dispersion step, an excellent dispersion state can be obtained in the dielectric ceramic paste as compared with Samples 1 and 2, which did not perform such a process.
Reflecting this, “surface roughness”, “thickness variation”
Further, it can be seen that the results are more excellent in the “structural defect defect rate”.

[0109]

[Experiment 2] Experiment 2 relates to a multilayer inductor.

1. Preparation of Magnetic Ceramic Powder First, 49.0 mol% of ferric oxide and 29.90% of zinc oxide were used.
It was weighed so that 0 mol%, nickel oxide was 14.0 mol%, and copper oxide was 8.0 mol%, wet-mixed using a ball mill, and then dehydrated and dried. Then 750
After calcining at 1 ° C. for 1 hour, the powder was pulverized to obtain a magnetic ceramic powder.

[0111] 2. Preparation of ceramic slurry and preparation of ceramic green sheet 100 parts by weight of magnetic ceramic powder prepared above,
A dispersant comprising 0.5 part by weight of a maleic acid copolymer,
A solvent consisting of 30 parts by weight of methyl ethyl ketone and 20 parts by weight of toluene was put into a ball mill together with 600 parts by weight of a zirconia ball having a diameter of 1 mm, and stirred for 4 hours. 7 parts by weight of polyvinyl butyral and 3 parts by weight of DOP (dioctyl phthalate) as a plasticizer
And 20 parts by weight of ethanol were added, and the mixture was wet-mixed for 20 hours to obtain a magnetic ceramic slurry.

Then, a doctor blade method was applied to the magnetic ceramic slurry to form a 20 μm thick magnetic ceramic slurry.
A magnetic ceramic green sheet (having a thickness of 15 μm after firing) was formed. Drying was performed at 80 ° C. for 5 minutes.

3. Preparation of conductive paste 80 parts by weight of Ag metal powder, 20 parts by weight of Pd metal powder, 4 parts by weight of ethyl cellulose, 2 parts by weight of alkyd resin, and 35 parts by weight of butyl carbitol were kneaded with three rolls. Then, 35 parts by weight of terpineol was added to adjust the viscosity to obtain a conductive paste.

4. Preparation of Ceramic Paste for Step Absorbing Ceramic Green Layer-Samples 5 and 6 (Example) and Sample 8 (Comparative Example)
-100 parts by weight of the magnetic ceramic powder prepared above, 40 parts by weight of terpineol having a boiling point of 220 ° C., and 5 parts by weight of ethylcellulose resin were mixed in an automatic mortar and mixed.
The mixture was well kneaded with this roll to obtain a magnetic ceramic paste.

-Sample 7 (Example)-100 parts by weight of the magnetic ceramic powder prepared above, 70 parts by weight of methyl ethyl ketone having a boiling point of 79.6 ° C., and a quaternary ammonium polyacrylate ammonium salt dispersant (weight average molecular weight: 1000) 0.5 part by weight and 600 parts by weight of zirconia cobblestone having a diameter of 1 mm were put into a ball mill, and wet-mixed for 16 hours as a primary dispersion step. Next, 10 parts by weight of terpineol having a boiling point of 220 ° C. and 5 parts by weight of ethyl cellulose resin were added to the same pot, and the mixture was further mixed for 16 hours as a secondary dispersion step to obtain a magnetic ceramic slurry mixture. .

Next, the above-mentioned magnetic ceramic slurry mixture was distilled under reduced pressure in an evaporator at 60 ° C. for 2 hours to completely remove methyl ethyl ketone to obtain a magnetic ceramic paste. Then
For viscosity adjustment, 10 to 20 parts by weight of terpineol was added and dispersed and adjusted by an automatic mortar.

5. Preparation of composite structure In order to form a coil conductor extending in a coil shape after laminating a plurality of magnetic ceramic green sheets, at a predetermined position of the magnetic ceramic green sheet prepared earlier,
In order to form a through hole for a via hole conductor and to form a coil conductor film on the main surface of the magnetic ceramic green sheet and a via hole conductor in the through hole, a conductive paste is screen-printed, and the paste is formed at 80 ° C. for 10 minutes. Dried. Next, on the magnetic ceramic green sheet, to form a magnetic ceramic green layer for step absorption,
Screen printing of magnetic ceramic paste, 80 ℃
For 10 minutes. The thickness of each of the coil conductor film and the step-absorbing magnetic ceramic green layer was 30 μm after drying (the thickness after firing was 20 μm).

6. Rolling of Composite Structure -Sample 5 (Example)-The composite structure obtained as described above was sandwiched between two mirror-polished stainless steel metal plates, and heated at 50 ° C.
, And pressed for 1 minute under a pressing condition of 50 kg / cm ² .

-Samples 6 and 7 (Example)-The composite structure obtained as described above was lined with a carrier film made of polyethylene terephthalate as a support used in forming a dielectric ceramic green sheet. While in the state, a pair of mirror-polished stainless steel calender rolls are placed at a speed of 2 m / min.
I passed. At this time, the calender roll was heated to 80 ° C., and the interval between the calender rolls was set to a size obtained by adding 29 μm to the thickness of the carrier film.

-Sample 8 (Comparative Example)-The composite structure obtained as described above was not rolled.

7. Completion of multilayer inductor Next, as described above, the coil conductor film and via-hole conductor
And a ceramic green layer for absorbing steps
9 magnetic ceramic green sheets, ie, 9
Layers of composite structure so that coil conductors are formed.
And no coil conductor film etc.
6 magnetic ceramic green sheets
And a laminate of 1000 K at 80 ° C.
g / cm ^TwoWas hot pressed under pressure.

Next, the above-mentioned green laminate was cut with a cutting blade so as to have a length of 1.0 mm × a width of 0.5 mm × a thickness of 0.5 mm after firing. I got a body chip.

Next, on the firing setter on which a small amount of zirconia powder was sprayed, the above-mentioned plurality of laminated chips were aligned, and the temperature was raised from room temperature to 250 ° C. over 24 hours to remove the organic binder. Next, the laminated chip was put into a firing furnace and fired at a maximum of 970 ° C. with a profile of about 20 hours.

Next, the obtained sintered body chip was put into a barrel, and the end face was polished. After that, external electrodes mainly composed of silver were provided at both ends of the sintered body to form a chip-shaped chip as a sample. Completed a multilayer inductor.

8. Evaluation of Characteristics Experimental Example 1 of the multilayer inductor according to the above-described sample.
"Surface roughness", "Thickness variation", and "Structural defect defect rate" were evaluated in the same manner as in the above case. The results are shown in Table 2.

[0126]

[Table 2]

In Table 1, when comparison is made between Samples 5 to 7 as Examples and Sample 8 as Comparative Examples, Samples 5 to 7 according to Examples are compared with Sample 4 as Comparative Example. It can be seen that excellent results are shown in “surface roughness”, “thickness variation” and “structural defect defect rate”.

In particular, when comparing Samples 5 to 7 as Examples, in order to obtain a magnetic ceramic paste for the ceramic green layer for absorbing a step, a primary dispersion step and a secondary dispersion step were employed. According to Sample 7, in which the organic binder was added in the secondary dispersion step, an excellent dispersion state can be obtained in the magnetic ceramic paste as compared with Samples 5 and 6, which did not perform such a process.
Reflecting this, “surface roughness”, “thickness variation”
Further, it can be seen that the results are more excellent in the “structural defect defect rate”.

As described above, the case where the dielectric ceramic powder or the magnetic ceramic powder is used as the ceramic powder contained in the ceramic paste according to the present invention has been described. However, in the present invention, the electric characteristics of the ceramic powder used are influenced by the ceramic powder. Therefore, even if, for example, an insulating ceramic powder or a piezoelectric ceramic powder is used, a ceramic paste that can be expected to have the same effect can be obtained.

[0130]

As described above, according to the present invention, by forming the step absorbing ceramic green layer,
In a raw laminate, between a portion where internal circuit element films such as internal electrodes and coil conductor films are located and a portion where it is not, or a portion where a relatively large number of internal circuit element films are arranged in the stacking direction And a ceramic green sheet, an internal circuit element film, and a step-absorbing ceramic green layer for producing a green laminate. Since the surfaces of the composite structures are smoothed by rolling before the composite structures are stacked, unevenness on the surfaces of the composite structures can be eliminated, and variations in the thickness can be reduced.

As a result, undesired deformation hardly occurs in the raw laminate, and problems such as structural defects such as delamination and minute cracks and short-circuit defects do not easily occur in the obtained multilayer ceramic electronic component. can do.

Therefore, the ceramic green sheet used for manufacturing the multilayer ceramic electronic component can be advantageously made thinner, and even if such thinning proceeds, structural defects are less likely to occur and reliability is reduced. A high multilayer ceramic electronic component can be realized. In addition, it is possible to realize a highly reliable multilayer ceramic electronic component that does not easily cause structural defects even when the thickness of an internal circuit element film such as an internal electrode or a coil conductor film is increased.

As described above, according to the present invention, it is possible to sufficiently cope with a demand for a reduction in the size, thickness, and weight of a multilayer ceramic electronic component. When the present invention is applied to a multilayer ceramic capacitor, In addition, the multilayer ceramic capacitor can be advantageously reduced in size or thickness and increased in capacity.

In the present invention, the above-mentioned ceramic paste for forming the step absorption ceramic green layer comprises a primary dispersion step of dispersing a primary mixture containing at least a ceramic powder and a first organic solvent; A secondary dispersion step of subjecting the secondary mixture obtained by adding at least an organic binder to the primary mixture that has undergone the secondary dispersion step, and a primary mixture and / or a second organic solvent having a higher boiling point than the first organic solvent. After the step of including in the next mixture, after the secondary dispersion step, by heating treatment of the secondary mixture, by the removal step of selectively removing the first organic solvent, it is produced through a ceramic paste, An excellent dispersion state can be obtained, and the above-described effects are more remarkably exhibited.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically illustrating a part of a green laminate 3a for explaining a method of manufacturing a multilayer ceramic capacitor according to an embodiment of the present invention, which is of interest to the present invention. .

FIG. 2 is a plan view showing a part of a composite structure 6 manufactured in the method for manufacturing the multilayer ceramic capacitor shown in FIG.

FIG. 3 is a cross-sectional view schematically showing a multilayer chip 4a manufactured in the method for manufacturing the multilayer ceramic capacitor shown in FIG.

FIG. 4 is a cross-sectional view schematically showing a state where rolling is performed on the composite structure 6 shown in FIG. 2 by applying a calender roll method.

FIG. 5 is an exploded perspective view showing elements constituting a raw laminate 13 prepared for manufacturing a laminated inductor according to another embodiment of the present invention.

6 is a perspective view showing the appearance of a multilayer inductor 11 including a multilayer chip 12 obtained by firing the raw multilayer body 13 shown in FIG.

FIG. 7 is a cross-sectional view schematically illustrating a part of a raw laminate 3 for explaining a method of manufacturing a conventional multilayer ceramic capacitor that is interesting to the present invention.

8 is a plan view showing a part of a ceramic green sheet 2 on which an internal electrode 1 is formed, which is manufactured in the method for manufacturing a multilayer ceramic capacitor shown in FIG.

9 is a cross-sectional view schematically showing a multilayer chip 4 manufactured in the method for manufacturing the multilayer ceramic capacitor shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Internal electrode (internal circuit element film) 2, 14-19 Ceramic green sheet 3a, 13 Raw laminated body 4a, 12 Laminated chip 5, 22, 25, 28, 30 Ceramic green layer for step difference absorption 6 Composite structure 7 , 8 Calendar roll 11 Multilayer inductor (multilayer ceramic electronic component) 20, 23, 26, 29 Coil conductor film (internal circuit element film)

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Koji Kimura, Inventor 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto F-term in Murata Manufacturing Co., Ltd. (Reference) 5E001 AB03 AH01 AH05 AH09 AJ01 AJ02 5E070 AA01 AB02 CB02 CB13 CC02 5E082 AB03 BC38 BC40 EE04 EE35 FG06 FG26 FG54 LL01 LL02 MM22 MM24

Claims (10)

[Claims] 1. A ceramic green sheet obtained by preparing a ceramic slurry, a conductive paste, and a ceramic paste, and forming the ceramic slurry, and providing a step on the main surface of the ceramic green sheet due to its thickness. And an internal circuit element film formed by partially applying the conductive paste, and the main surface of the ceramic green sheet so as to substantially eliminate a step due to the thickness of the internal circuit element film. Producing a plurality of composite structures, comprising a step absorption ceramic green layer formed by applying the ceramic paste to a region where the internal circuit element film is not formed, and stacking the plurality of the composite structures. To produce a raw laminate, and firing the raw laminate A method of manufacturing a multilayer ceramic electronic component, comprising: forming, prior to stacking a plurality of the composite structures, further comprising: smoothing a surface of each of the composite structures by rolling. Method of manufacturing ceramic electronic components. 2. The method of claim 1, wherein the rolling is performed by applying a calender roll method to each of the composite structures. 3. The method for manufacturing a multilayer ceramic electronic component according to claim 1, wherein the rolling is performed by applying a method in which each of the composite structures is pressed between two metal plates. 4. The ceramic paste contains at least ceramic powder and a first organic solvent.
A first dispersion step of dispersing the next mixture; a second dispersion step of dispersing a second mixture obtained by adding at least an organic binder to the first mixture after the first dispersion step; A step of including a high-boiling second organic solvent in the primary mixture and / or the secondary mixture; and, after the secondary dispersion step, heat-treating the secondary mixture to thereby form the first organic solvent. 4. The method for producing a multilayer ceramic electronic component according to claim 1, wherein the method is performed through a removing step of selectively removing a solvent. 5. The method according to claim 1, wherein the first ceramic powder comprises the second ceramic powder.
The method for producing a multilayer ceramic electronic component according to any one of claims 1 to 4, which has substantially the same composition as the ceramic powder of (1). 6. The method for manufacturing a multilayer ceramic electronic component according to claim 1, wherein the first and second ceramic powders are both dielectric ceramic powders. 7. The multi-layer ceramic electronic component according to claim 6, wherein the internal circuit element films are internal electrodes arranged so as to form a capacitance therebetween, and the multilayer ceramic electronic component is a multilayer ceramic capacitor. A manufacturing method of the multilayer ceramic electronic component according to the above. 8. The method for manufacturing a multilayer ceramic electronic component according to claim 1, wherein said first and second ceramic powders are both magnetic ceramic powders. 9. The method of manufacturing a multilayer ceramic electronic component according to claim 8, wherein the internal circuit element film is a coil conductor film extending in a coil shape, and the multilayer ceramic electronic component is a multilayer inductor. 10. A multilayer ceramic electronic component obtained by the manufacturing method according to claim 1.