KR20130034848A - Multilayer ceramic capacitor and manufacturing method thereof - Google Patents

Abstract

PURPOSE: A multilayer ceramic capacitor and a manufacturing method thereof are provided to improve capacitance thereof using an inner electrode, and to prevent dielectric breakdown. CONSTITUTION: A ceramic body(10) disperses semiconducting particles. An inner electrode(31,32) faces the inner part of the ceramics body. The volume ratio of semiconducting particles is in the range of 3 to 7. The semiconducting particles consist of silicon particles or semiconducting oxide particles. The ceramic body includes barium titanate.

Description

Multilayer Ceramic Capacitor and Manufacturing Method Thereof

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer ceramic electronic component and a method of manufacturing the same, and more particularly, to a multilayer ceramic electronic component and a method of manufacturing the same having increased dielectric constant and capacitance.

Multilayer ceramic capacitors are widely used as components of mobile communication devices such as computers, PDAs, and mobile phones due to their small size, high capacity, and easy mounting.

Recently, as electronic products are miniaturized and multifunctional, chip components are also miniaturized and highly functional. Therefore, multilayer ceramic capacitors are also required to have high capacity products with small sizes and large capacities.

In order to increase the capacity of the multilayer ceramic capacitor, the thickness of the dielectric layer and the internal electrode layer should be made thinner and the number of stacked layers should be increased.

However, as the dielectric layers and internal electrodes become thinner and the number of stacked layers increases, the likelihood of dielectric breakdown increases, and interlayer delamination and cracks occur, which may lower the reliability of the multilayer ceramic capacitor. .

Accordingly, there is a limit in miniaturization and high capacity of the multilayer ceramic capacitor.

An object of the present invention is to provide a multilayer ceramic electronic component having improved dielectric constant and capacitance and a method of manufacturing the same.

In one embodiment, a multilayer ceramic electronic component includes a ceramic body having semiconductive particles dispersed therein; And internal electrodes disposed to face the inside of the ceramic body.

The ratio of the volume of the semiconductive particles to the volume of the ceramic body may be 3 or more and 7 or less.

The ceramic body may comprise barium titanate.

The semiconductive particles may be silicon particles or semiconductive oxide particles.

The semiconductive oxide may include any one or more of indium tin oxide or ruthenium oxide which have been heat-treated by reduction.

The reduction heat treatment may be performed in a 1000 ℃ to 1100 ℃ hydrogen atmosphere.

According to another aspect of the present invention, there is provided a method of manufacturing a multilayer ceramic electronic component, comprising: weighing the ceramic powder and the semiconductive powder such that a ratio of the volume of the semiconductive powder to the volume of the ceramic powder is 3 or more and 7 or less; And adding an organic solvent, a binder, and the like to the mixture of the ceramic powder and the semiconducting powder: and preparing a ceramic slurry by ball milling the mixture.

After preparing the ceramic slurry, the method may further include preparing a ceramic green sheet by using the ceramic slurry and stacking the ceramic green sheet.

The ceramic powder may include barium titanate powder.

The semiconductive powder may be silicon powder or semiconductive oxide powder.

The semiconducting oxide may be indium tin oxide or ruthenium oxide which has been subjected to reduction heat treatment.

The reduction heat treatment may be performed in a 1000 ℃ to 1100 ℃ hydrogen atmosphere.

According to the present invention, a multilayer ceramic electronic component having improved dielectric constant and capacitance can be obtained.

1 is a perspective view of a multilayer ceramic electronic component according to one embodiment of the present invention.
FIG. 2 is a cross-sectional view along the line XX ′ of FIG. 1.
Fig. 3 is a modification of Fig.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention may be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below.

Furthermore, embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art.

Accordingly, the shapes and sizes of the elements in the drawings may be exaggerated for clarity of description, and the elements denoted by the same reference numerals in the drawings are the same elements.

1 is a perspective view of a multilayer ceramic electronic component according to one embodiment of the present invention. FIG. 2 is a cross-sectional view along the line X-X 'of FIG.

The multilayer ceramic electronic component may include a multilayer ceramic capacitor, chip inductor, chip beads, and the like. Although the present invention will be described in detail with reference to the multilayer ceramic capacitor as an example, the present invention is not limited thereto.

1 and 2, the multilayer ceramic electronic component according to the present embodiment includes a ceramic body 10, external electrodes 21 and 22 formed outside the ceramic body, and internal electrodes 31 formed inside the ceramic body. , 32).

The ceramic body 10 may be a rectangular parallelepiped. A direction in which the first and second external electrodes 21 and 22 are connected in a 'length direction' is a direction in which the internal electrodes 31 and 32 are stacked in a 'lamination direction' or a 'thickness direction', the length direction and the lamination. The direction perpendicular to the direction may be referred to as the 'width direction'.

The ceramic body 10 may have a length greater than a width and a thickness, and the width and the thickness may be the same.

The ceramic body 10 may have the semiconductive particles 30 dispersed therein.

The ceramic body 10 may be made of a ceramic material having a high dielectric constant, but is not limited thereto, and may be a barium titanate (BaTiO ₃ ) -based material or a strontium titanate (SrTiO ₃ ) -based material.

The ceramic body 10 is sintered after stacking a plurality of dielectric layers, and adjacent dielectric layers may be integrated to such an extent that the boundary thereof cannot be confirmed.

Semiconducting particles refer to particles having semiconducting properties, and the semiconducting particles may be silicon particles or semiconducting oxide particles.

The semiconducting particles may be particles of carbon and germanium which are tetravalent elements other than silicon.

A semiconducting oxide refers to an oxide having semiconductor properties among oxides.

Semiconducting oxides refer to oxides whose voltage-current characteristics are as follows. That is, in the case of the semiconducting oxide, when the applied voltage is low, almost no current flows, but as the applied voltage exceeds the threshold, the current increases as the applied voltage increases.

A characteristic of semiconducting materials is that some electrons are not free electrons, as in metals, but electrons with moderate band gap energy that are not distributed in a valence band with high band gap energy such as insulators. It exists.

When no voltage is applied, it exhibits the same characteristics as an insulator, but when voltage is applied, it exhibits the same behavior as free electrons. In this case, the motion in the state where the voltage is applied is isolated to the dielectric layer made of the insulator, thereby dipolar polarization. It causes polarization, similar to causing behavior.

The polarization action by free electrons is a small value proportional to the square of the refractive index of the material. However, the electrons trapped in the semiconducting particles exhibit the same characteristics as the grain-boundary barrier layer capacitor (GBLC) to achieve high dielectric constant. have.

The semiconducting oxide may comprise at least one of reduced heat treated indium-tin oxide or ruthenium oxide.

In addition, semiconductive oxides can be at least one selected from molybdenum oxide, iron oxide, tin oxide, zinc oxide, a group of _{CeO 2, Ga 2 O 3,} SrTiO 3, LaFeO 3, Cr x Ti y O 3.

Indium-specific examples of the tin oxide or ruthenium oxide _{RuO 2, IrO 2, ReO 3} , SrVO 3, SrRuO 3, SrMoO 3, CaRuO 3, BaRuO 3, PbRuO 3, BiRuO 3, LaTaO 3, Bi 2 Ru 2 O 7 Etc. can be mentioned.

In short, the semiconducting oxide can be prepared as follows. That is, a semiconductive oxide having a specific resistance of 10 ⁵ to 10 ⁸ Ωcm can be prepared by heat-treating an oxide having a specific resistance of 10 ¹² to 10 ¹⁴ Ωcm in a reducing atmosphere.

The reduction heat treatment may be performed in a 1000 ℃ to 1100 ℃ hydrogen atmosphere. The hydrogen concentration may be 1 to 3%, and the heat treatment may be performed for 2 to 10 hours.

Reduction heat treatment refers to the operation of applying heat in a space deficient in oxygen. When oxygen is insufficient in air, oxygen ions or oxygen atoms occupying a lattice in the conductive oxide may escape into the air. At this time, the oxygen atom leaves two electrons in the oxide as it exits in the form of oxygen molecules into the air, and the electrons can be semiconducting by the electrons.

The ratio of the volume of the semiconductive particles to the volume of the ceramic body may be 3 or more and 7 or less.

When the ratio of the volume of the semiconducting particles to the volume of the ceramic body is less than 3, the increase in dielectric constant of the ceramic body is insignificant, so that the capacitance of the laminated ceramic electronic component is also insignificant.

On the other hand, when the ratio of the volume of the semiconducting particles to the volume of the ceramic body exceeds 7, the gap between the semiconducting particles is narrowed, which may cause electrical conduction by the semiconducting particles. Insulation resistance may be lowered.

Since the semiconductive particles can be connected to form a new conductive passage, the ratio of the volume of the semiconductive particles to the volume of the ceramic body may be an important factor.

Adding semiconductive particles to the ceramic body may increase the dielectric constant of the ceramic body.

Conventional multilayer ceramic capacitors have secured the product's capacitance by realizing the dielectric constant using the dielectric phenomenon caused by the polarization of the dielectric.

As in the present invention, in the case where the semiconductive particles are dispersed in the dielectric, in addition to the existing dielectric phenomenon, the dielectric constant may be further increased due to the addition of the pseudopolarization action of the trapped electrons to the semiconducting particles.

In other words, electrons are trapped in the semiconducting particle, and the semiconducting properties of these electrons are similar to the polarization action by the dipole, and the dielectric constant may increase because the properties of the semiconducting particle are added to the dielectric properties of the existing dielectric. Can be.

Although the semiconductive particle has been exemplified in detail above, the present invention is not limited thereto, and a polarization phenomenon may be performed under a constant electric field.

Dispersing the semiconductive particles in the dielectric increases the dielectric constant of the dielectric, and this increase in dielectric permits the reduction of the number of internal electrodes stacked in the design of the capacitor product, thereby greatly reducing the cost burden.

The external electrodes 21 and 22 may be formed on the outer surface of the ceramic body 10.

The external electrodes 21 and 22 may be formed using a conductive paste including a conductive metal and glass frit, but the conductive metal may be made of copper, a copper alloy, nickel, a nickel alloy, silver, palladium, or the like. have.

The external electrodes 21 and 22 may be formed on both side surfaces of the ceramic body 10. In this case, the external electrodes 21 and 22 may be connected to the internal electrodes 31 and 32 formed to be exposed on one surface of the ceramic body 10.

The internal electrodes 31 and 32 may be stacked and disposed in the ceramic body 10.

The internal electrodes 31 and 32 may be formed such that one end is exposed to one surface of the ceramic body 10. If one end of one of the internal electrodes 31 is formed to be exposed to one surface of the ceramic body 10, one end of the inner electrode 32 adjacent thereto may be formed to be exposed to the opposite surface of the ceramic body 10. .

The internal electrodes 31 and 32 may generally be formed by printing a paste including a conductive metal, a binder, and a solvent on a dielectric green sheet and then baking the paste. Nickel (Ni), a nickel alloy, etc. can be used as a conductive metal. The conductive paste composition for internal electrodes may further include a ceramic common material, for example barium titanate. Polymer binders, such as polyvinyl butyral and ethyl cellulose, can be used as a binder. The solvent of the electrically conductive paste for internal electrodes is not restrict | limited, For example, terpineol, dihydroterpineol, butyl carbitol, a kerosene, etc. can be used.

The internal electrodes 31 and 32 may be formed on the dielectric green sheet by a method such as screen printing or gravure printing.

According to another aspect of the present invention, there is provided a method of manufacturing a multilayer ceramic electronic component, comprising: weighing the ceramic powder and the semiconductive powder such that a ratio of the volume of the semiconductive powder to the volume of the ceramic powder is 3 or more and 7 or less; And adding an organic solvent, a binder, and the like to the mixture of the ceramic powder and the semiconducting powder: and preparing a ceramic slurry by ball milling the mixture.

After preparing the ceramic slurry, the method may further include preparing a ceramic green sheet by using the ceramic slurry and stacking the ceramic green sheet.

In order to evenly disperse the semiconductive particles in the ceramic body, the ceramic powder and the conductive powder are weighed to have a volume ratio of 3 to 7, and then an organic solvent, a binder, a plasticizer, and other additives are added thereto, and alumina, zirconia, or the like is added thereto. The ceramic slurry can be manufactured by carrying out three roll ball milling using a ceramic ball.

Using a ceramic slurry in which semiconductive particles are evenly dispersed, a polymer film is applied to a carrier film through a method such as a doctor blade, and then dried to prepare a green sheet, followed by lamination to manufacture a laminated type capacitor. Can be.

However, the present invention is not limited thereto, and the capacitor of the bulk type may be manufactured as shown in FIG.

The ceramic powder may include barium titanate.

The semiconductive powder may be silicon powder or semiconducting oxide. The semiconducting oxide may be indium tin oxide or ruthenium oxide which has been subjected to reduction heat treatment. The reduction heat treatment may be performed in a 1000 ℃ to 1100 ℃ hydrogen atmosphere.

In the present embodiment, the matters related to the ceramic powder and the semiconductive oxide are the same as described above.

[Example]

A multilayer ceramic capacitor was manufactured by the following method.

First, indium tin oxide (ITO) having an average particle size of 250 nanometers was heat-treated in a hydrogen atmosphere at 1000 ° C to 1100 ° C and hydrogen concentration of 1 to 3% for 10 hours, so that the resistivity was about 10 ⁵ to 10 ^A semiconducting oxide of ⁸ cm 3 was prepared.

As the dielectric powder, barium titanate powder having an average particle size of 300 nanometers was prepared.

Next, the ratio of the volume of the semiconducting ITO particles to the ceramic body was measured to be 0%, 1%, 2.5%, 5%, and 10%.

Next, barium titanate powder is mixed with additives such as ethanol and a binder to produce a ceramic slurry in which ceramic powder is evenly dispersed by ball milling. Sheets were prepared.

Next, additives such as a solvent and a binder were added to the barium titanate and the semiconductive ITO mixed powder, and ball milling was performed to prepare a ceramic slurry in which the semiconducting ITO was evenly dispersed. The ceramic slurry was applied onto a polyethylene film through a doctor blade method and dried to prepare a ceramic green sheet.

Next, an internal electrode paste containing nickel as a main component was used to form internal electrodes on the ceramic green sheet using screen printing, and the green sheets were laminated to form a laminate, and the laminate was 1,000 kgf / After isostatic pressing at a pressure of cm 2, the laminate was cut to prepare a green chip.

The green chip was dipped in an external electrode paste and dried to form an external electrode on an outer surface of the green chip.

After the green chip on which the external electrode was formed was subjected to a binder removal process maintained at 230 ° C. for 60 hours in an air atmosphere, the green chip was baked at 900 ° C. in a reducing atmosphere, and the internal electrode and the external electrode were simultaneously fired.

Through the above process, a multilayer ceramic capacitor in which ITO, which is a conductive oxide, was evenly dispersed in the ceramic body was manufactured.

Table 1 shows the results of measuring dielectric constant and capacitance while changing the ratio of the volume of semiconductive ITO particles in the volume of the ceramic body.

Barium titanate Semiconductor ITO Volume ratio of semiconductive particles to ceramic body (%) permittivity Capacitance
(uF) size
(nm) Volume ratio
(vol%) size
(nm) Volume ratio
(vol%) Comparative Example 1 * 300 100 - - 0 3250 9.9 Comparative Example 2 * 300 99 250 One One 3310 10.3 Comparative Example 3 * 300 97.5 250 2.5 2.5 3560 11.0 Example 300 95 250 5 5 3930 12.9 Comparative Example 4 * 300 90 250 10 10 5900 18.8

*: Not within the scope of the present invention.

Referring to Table 1, Comparative Example 1 is a case where the semiconducting ITO is not added to the ceramic body, the dielectric constant is 3250, the capacitance is 9.9uF, Comparative Example 2 is the case where the volume ratio of the semiconducting ITO is 1%, the dielectric constant is 3310, the capacitance is 10.3 uF, Comparative Example 3 is a case where the volume ratio of the semiconducting ITO is 2.5%, the dielectric constant is 3560, the capacitance is 11.0 uF.

In Example 3, the volume ratio of the semiconducting ITO to the ceramic body is 5%. The dielectric constant is 3930 and the capacitance is 12.9 uF.

In Comparative Example 4, the volume ratio of the semiconducting ITO to the ceramic body was 10%. The dielectric constant was 5900 and the capacitance was 18.8 uF.

According to Table 1, it can be seen that the dielectric constant and capacitance increase as the content of the semiconducting ITO increases.

In particular, it can be seen that in Example 3 having a volume ratio of semiconducting ITO, dielectric constant and capacitance increase rapidly.

In the case of Comparative Example 4, the dielectric constant and capacitance have a considerably large value, but are not within the scope of the present invention. The reason for this is that as the volume occupied by the semiconducting ITO increases, the interval between the semiconducting ITO particles is shortened, thereby reducing the insulation resistance of the ceramic body.

The present invention is not limited by the above-described embodiments and the accompanying drawings, but is intended to be limited only by the appended claims. It will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. something to do.

10: Ceramic body
21, 22: (first and second) external electrodes
30: semiconductive particle
31, 32: internal electrode

Claims (12)

A ceramic body in which semiconductive particles are dispersed therein; And
Internal electrodes disposed to face the interior of the ceramic body;
Laminated ceramic electronic component comprising a.
The method of claim 1,
The ratio of the volume of the semiconductive particle to the volume of the ceramic body is 3 to 7 or less multilayer ceramic electronic component.
The method of claim 1,
The ceramic body is a multilayer ceramic electronic component comprising barium titanate.
The method of claim 1,
The semiconducting particles are silicon particles or semiconductive oxide particles.
5. The method of claim 4,
The semiconducting oxide comprises at least one of reduced heat treated indium-tin oxide or ruthenium oxide.
The method of claim 5,
The reduction heat treatment is a multilayer ceramic electronic component carried out in a 1000 ℃ to 1100 ℃ hydrogen atmosphere.
Weighing the ceramic powder and the semiconductive powder such that the ratio of the volume of the semiconductive powder to the volume of the ceramic powder is 3 or more and 7 or less;
Adding an organic solvent, a binder, and the like to the mixture of the ceramic powder and the semiconductive powder: and
Ball milling the mixture to prepare a ceramic slurry;
Method of manufacturing a multilayer ceramic electronic component comprising a.
The method of claim 7, wherein
After the preparing of the ceramic slurry, further comprising preparing a ceramic green sheet by using the ceramic slurry and stacking the ceramic green sheet.
The method of claim 7, wherein
The ceramic powder is a manufacturing method of a multilayer ceramic electronic component containing barium titanate powder.
The method of claim 7, wherein
The semiconducting powder is a silicon powder or a semiconducting oxide powder.
The method of claim 10,
The semiconducting oxide is a reduction heat treatment indium tin oxide or ruthenium oxide manufacturing method of a multilayer ceramic electronic component.
The method of claim 11,
The reduction heat treatment is a method of manufacturing a multilayer ceramic electronic component is carried out at 1000 ℃ to 1100 ℃ hydrogen atmosphere.

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