KR20160069816A - Multi-layer ceramic capacitor and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a multilayered ceramic capacitor to improve chip reliability by preventing a decrease in insulation resistance (IR) properties in a high humidity environment, and a manufacturing method thereof. According to the present invention, the multilayered ceramic capacitor comprises: a ceramic main body and an external electrode. A hydrophobic protective layer with the content of Fluorine (F) of 0.2-0.7% is formed on a surface of the ceramic main body exposed between the external electrodes.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer ceramic capacitor,

The present invention relates to a multilayer ceramic capacitor and a method of manufacturing the same.

In general, an electronic component using a ceramic material such as a capacitor, an inductor, and a piezoelectric element includes a ceramic body made of a ceramic material, internal electrodes formed inside the ceramic body, and external terminals provided on the surface of the ceramic body to be connected to the internal electrodes .

A multi-layer ceramic capacitor (MLCC) in a ceramic electronic part includes a plurality of ceramic dielectric sheets, an inner electrode interposed between the plurality of ceramic dielectric sheets, and an outer electrode electrically connected to the inner electrode.

Such MLCCs are small in size, can realize high capacitance, can be easily mounted on a substrate, and are widely used as capacitive parts of various electronic devices.

Recently, as the climate environment becomes increasingly harsh, MLCCs are required to have reliability (Insulation Resistance; IR) characteristics in harsh environments (high temperature, high humidity, high pressure, high ESD, etc.).

Korean Patent Publication No. 10-2005-0048855

An object of the present invention is to provide a multilayer ceramic capacitor capable of preventing degradation of IR (Insulation Resistance) characteristics in a high humidity environment and improving chip reliability.

It is also an object of the present invention to provide a method of manufacturing a multilayer ceramic capacitor capable of preventing a reduction in IR characteristics in a high humidity environment.

The object of the present invention is to provide a multilayer ceramic capacitor,

The present invention relates to a multilayer ceramic capacitor manufactured by a debindering process, a sintering process, and an external electrode formation process in a green process. In the multilayer ceramic capacitor, In order to prevent the IR characteristics of the liquid crystal display device from being degraded.

This is because the outer surface of the multilayer ceramic capacitor subjected to the sintering process forms a porous structure.

In order to achieve the above object, the present invention can be achieved by providing a multilayer ceramic capacitor in which a hydrophobic protective film containing fluorine (F) is formed on the surface of a ceramic body.

At this time, the hydrophobic protective film may be formed of CF ^{2 -} , CF ^{3 -} , and CF ^{3 -} based fluorocarbon-based compounds having a fluorine (F) content of 0.2% to 0.7%.

The hydrophobic protective film having a fluorine (F) content of 0.2% to 0.7% is subjected to a plasma treatment for 5 to 30 seconds under conditions of an RF power of 150 W to 160 W and a reaction gas flow rate of 200 sccm to 300 sccm And then performing a plasma treatment process.

According to the present invention, since the hydrophobic protective film containing fluorine (F) is formed on the surface of the ceramic body, moisture trapping and moisture wetting on the outer surface of the multilayer ceramic capacitor are suppressed in a high humidity environment, .

1 is a perspective view of a multilayer ceramic capacitor according to an embodiment of the present invention.
2 is a cross-sectional view taken along line I-I 'of FIG.
Fig. 3 is a partially exploded perspective view of the ceramic sheet used in the lamination of the ceramic body of Fig. 1; Fig.
4 is a flowchart showing a manufacturing process of a multilayer ceramic capacitor according to an embodiment of the present invention.
FIGS. 5 to 8 are process drawings showing a method of manufacturing the multilayer ceramic capacitor according to FIG. 4,
5 is a cross-sectional view in which coating layers of external electrodes are formed on both ends of the ceramic body,
6 is a cross-sectional view in which a hydrophobic protective film is formed on the coating layer of the external electrode and the exposed ceramic body,
7 is a cross-sectional view of the polished hydrophobic protective film,
8 is a cross-sectional view in which a plating layer is formed on a coating layer of an external electrode.

The terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. Also, " comprise "and / or" comprising "when used herein should be interpreted as excluding the presence or addition of the mentioned forms, numbers, steps, operations, elements, elements and / It is not.

BRIEF DESCRIPTION OF THE DRAWINGS The objectives, specific advantages and novel features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. It should be noted that, in the present specification, the reference numerals are added to the constituent elements of the drawings, and the same constituent elements are assigned the same number as much as possible even if they are displayed on different drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. The terms first, second, etc. in this specification are used to distinguish one element from another element, and the element is not limited by the terms.

Hereinafter, a multilayer ceramic capacitor and a method of manufacturing the same according to the present invention will be described in detail with reference to FIGS. 1 and 8. FIG.

FIG. 1 is a perspective view of a multilayer ceramic capacitor according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line I-I 'of FIG. 1, Fig.

1 and 2, a multilayer ceramic capacitor 100 according to the present embodiment includes a ceramic body 110, a pair of external electrodes 120 formed at both ends of the ceramic body 110, And a hydrophobic protective film 130 formed on the surface of the ceramic body 110 exposed through the insulating layer 120.

The ceramic body 110 is a body of the multilayer ceramic capacitor 100 and is formed by stacking a plurality of dielectric layers 112 therein and inserting the internal electrodes 114 between the plurality of dielectric layers 112 .

At this time, the dielectric layer 112 is a ceramic dielectric layer made of ceramic, and is a ceramic dielectric sheet made in the form of a sheet.

The ceramic body 110 is formed of a ceramic green sheet composed of a ferroelectric material such as barium titanate, which is completed in a laminated form through a plurality of lamination, pressing, and firing steps. Are so integrated that they can not distinguish their boundaries. Accordingly, the drawings are also shown integrally without discrimination of each ceramic sheet.

As shown in FIG. 2, the internal electrodes 114 are interposed between the plurality of dielectric layers 112, and the positive electrodes and the negative electrodes may be alternately arranged.

In this case, the first ceramic sheet 116 having the internal electrode 114 formed therein so that one end thereof is exposed to the outside, and the second ceramic sheet 116 having the second internal electrode 114 having the other end opposite to the one end exposed to the outside, The ceramic sheets 118 may be alternately stacked and then fired to form the ceramic body 110 of FIG.

In other words, the ceramic body 110 is formed so that the direction of the layer- A plurality of ceramic sheets on which the internal electrodes 114 are printed may be stacked.

The internal electrode 114 may be formed of one or more metals or alloys thereof selected from a conductive material, for example, Ni, Pd, Al, Fe, Cu, Ti, Cr, Au, have.

The internal electrode 114 may be formed of a metal thin film formed by sintering after a conductive paste such as a metal paste is applied on one surface of a ceramic sheet.

1 and 2, external electrodes 120 are formed at both ends of the ceramic body 110. [

The external electrode 120 may be connected to the internal electrode 114 whose end is exposed to the outside of the ceramic body 110 to serve as an external terminal for electrically connecting the internal electrode 114 and the external device.

One of the pair of external electrodes 120 is connected to the internal electrode 114 whose one end is exposed to the outside of the ceramic body 110 and the other is connected to the internal electrode 114 exposed to the outside of the ceramic body 110 (114).

For example, the internal electrode 114 connected to the external electrode 120 formed on one side of the ceramic body 110 may be an anode and the internal electrode 114 connected to the external electrode 120 formed on the other side of the ceramic body 110 ) May be a cathode.

The external electrode 120 is composed of a coating layer 122 and a plating layer 124 sequentially stacked on the ceramic body 110.

At this time, the coating layer 122 is formed on the surfaces of the both ends of the ceramic body 110, and may include conductive metal powder and glass frit.

The conductive metal powder is not particularly limited as long as it is for producing an external electrode, and may be, for example, copper (Cu).

The glass frit is preferably added for the purpose of improving the corrosion resistance of the plating liquid at the time of forming the plating layer 124, but may be omitted.

The coating layer 122 is formed by dispersing glass frit and conductive metal powder in an organic vehicle to prepare a paste, applying the paste to both ends of the ceramic body 110, and then forming a sintered metal thin film by sintering .

Here, the organic vehicle may be an organic binder that imparts liquid-phase characteristics to the paste composition, and may further include an organic solvent.

Of the layers constituting the external electrode 120, the plating layer 124 is formed on the coating layer 122 by a plating process.

This plating layer 124 is formed at the outermost portion of the external electrode 120 as a layer formed for the purpose of improving the solderability when the multilayer ceramic capacitor 100 is mounted on the circuit board.

The plating layer 124 may be formed as a single layer or a multilayer using a metal having excellent solderability such as tin (Sn), nickel (Ni), copper (Cu) or the like from the viewpoint of improvement in solderability. In Fig. 2, a plating layer 124 composed of a single layer is shown.

The hydrophobic protective film 130 of the present embodiment is formed for the purpose of preventing moisture trapping or moisture wetting on the surface of the ceramic body 110 of the chip-type multilayer ceramic capacitor 100 in a humid environment.

The hydrophobic protective film 130 is formed on the surface of the ceramic body 110 exposed between the pair of external electrodes 120, that is, the surface of the dielectric layer 112.

The hydrophobic protective layer 130 is a surface modifying coating layer formed by including a hydrophobic group having a low affinity for moisture and hydrophobic surface-modifying the surface of the dielectric layer 112 which is hydrophilic.

For example, the hydrophobic protective film 130 may be formed of a CF ^{2 -} , CF ^{3 -} , or CF ^{3 -} based fluorocarbon compound in which at least one fluorine group (F ^- ) is introduced into a carbon (C) , Any one of them may be selected.

This is because the fluorine (F) atom is a substance having a high hydrophobicity, and when the fluorine atom is bonded to the carbon atom, the fluorine (F) atom has chemically very stable characteristics, so that the hydrophobicity and the chemical resistance can be ensured at the same time.

Substantially, the hydrophobic protective film 130 has a structure in which a carbon atom is bonded to the surface of the dielectric layer 112 and a fluorine atom bonded to the carbon atom is exposed to the outside, and the hydrophobic protective film 130 is hydrophobic by the fluorine atom.

When the hydrophobic protective film 130 having a hydrophobic group is interposed between the surfaces of the exposed dielectric layers 112 between the pair of external electrodes 120, the surface of the dielectric layer 112 is hydrophobic due to fluorine atoms having low affinity for moisture. So that moisture trapping and moisture wetting on the exposed surface of the dielectric layer 112 can be suppressed.

The hydrophobic protective film 130 of this embodiment preferably contains 0.2 to 0.7% of fluorine (F) in the film from the viewpoint of preventing moisture accumulation and moisture wetting.

At this time, if the content of fluorine (F) is less than 0.2%, the effect of preventing moisture trapping and moisture wetting may be insufficient, while if it exceeds 0.7%, the increase of the material cost may be caused without further improving the effect.

The hydrophobic protective film 130 is formed on the exposed surface of the ceramic body 110 and the coating layer 122 of the external electrode 120 by plasma treatment, as will be described in more detail in the following method of manufacturing the multilayer ceramic capacitor After the hydrophobic protective film 130 having a predetermined thickness is formed, a hydrophobic protective film 130 corresponding to the coating layer 122 is formed by grinding.

The multilayer ceramic capacitor 100 having the above structure is formed by forming the hydrophobic protective film 130 containing fluorine F on the exposed surface of the dielectric layer 112 between the external electrodes 120, The moisture trapping and moisture wetting can be suppressed. Thus, in the humid environment, deterioration of the IR characteristics of the multilayer ceramic capacitor 100 is prevented, and chip reliability can be improved.

A method of manufacturing the multilayer ceramic capacitor according to the present embodiment will be described as follows.

The manufacturing method of the multilayer ceramic capacitor of the present embodiment describes the embodiment shown in Fig. 1 and the material such as the dielectric layer 112, the internal electrode 114, the external electrode 120 and the hydrophobic protective film 130 is the same as the above- The same explanation will be omitted.

FIG. 5 is a cross-sectional view illustrating a process of manufacturing a multilayer ceramic capacitor according to an embodiment of the present invention. FIGS. 5 to 8 are views showing a method of manufacturing a multilayer ceramic capacitor according to FIG. 6 is a cross-sectional view of a coated layer of the external electrode and a hydrophobic protective film formed on the exposed ceramic body, FIG. 7 is a sectional view of the polished hydrophobic protective film, and FIG. 8 is a cross- In which a plating layer is formed.

As shown in FIGS. 4 and 5, a method of manufacturing a multilayer ceramic capacitor according to the present embodiment includes preparing a ceramic body 110 having external electrode coating layers 122 formed on both ends thereof.

The ceramic body 110 is prepared by preparing a plurality of ceramic green sheets for constituting the dielectric layer 112 and then printing the internal electrodes 114 so that the direction of the interlayer exposed ends is different on each ceramic green sheet, A plurality of ceramic green sheets printed with the ceramic green sheet 114 may be laminated, pressed, and sintered at a temperature of about 1000 ° C to 1300 ° C to form a sintered ceramic sheet and a sintered metal thin film internal electrode 114.

At this time, a plurality of ceramic green sheets may be prepared by mixing a ceramic powder, a binder, and a solvent to prepare a slurry, coating the slurry on a carrier film by a doctor blade method or the like, and drying the same to form a sheet having a thickness of several millimeters .

The internal electrode 114 can be formed by mixing a metal powder, a binder, and a solvent to prepare a metal paste, coating the metal paste on one surface of the ceramic green sheet by a doctor blade method, and then firing it.

The external electrode coating layer 122 is prepared by mixing a metal powder, a binder and a solvent to prepare a metal paste. The metal paste is applied to both ends of the ceramic body 110 by a doctor blade method or the like, To form a sintered metal thin film.

Next, as shown in FIGS. 4 and 6, a hydrophobic protective film 130 made of a fluorocarbon compound is formed on the exposed surface of the ceramic body 110 and the coating layer 122 of the external electrode 120.

The hydrophobic protective layer 130 may be formed through a known plasma treatment process. The reactive gas used to treat the surface of the dielectric layer 112 may be CF ₃ , CF ₄ , C ₂ F ₆ , C ₃ F ₆ , C ₄ F _8, and mixtures thereof may be used as the fluorocarbon gas.

Having a hydrophobicity of a certain thickness on the exposed surface of the coating layer 122 and the ceramic body 110 of the outer electrode 120 by the plasma treatment process using a fluorocarbon gas as a reactive gas CF ^2-, CF ^3-, CF ^- The surface of the dielectric layer 112 exhibiting the hydrophilic property is modified to be hydrophobic while the hydrophobic protective film 130 made of the fluorocarbon type compound is formed.

In the plasma treatment process, it is preferable to control process parameters such as an RF (Radio Frequency) power source, a plasma treatment time, and a reaction gas flow rate so that the fluorine (F) content of the hydrophobic protective film 130 may be 0.2% to 0.7% Do.

For example, when an RF power source in the range of 150 W to 160 W and a reactant gas flow rate in the range of 200 sccm to 300 sccm are used, the plasma processing time may be at least 5 seconds, preferably 5 to 30 seconds. At this time, if the plasma processing time is less than 5 seconds, the thickness of the film is too thin to cause the IR drop of the chip, and if it exceeds 30 seconds, the IR drop of the chip is improved, but unnecessary work time may be increased.

Next, as shown in FIGS. 4 and 7, the hydrophobic protective film 130 corresponding to the coating layer 122 is removed.

This is because if the coating layer 122 is covered with the hydrophobic protective film 130, it is difficult to form a plating layer on the coating layer 122 to improve solderability.

The removal process of the hydrophobic protective film 130 corresponding to the coating layer 122 may be performed by grinding to remove unwanted films.

The surface of the coating layer 122 is exposed by this polishing and the hydrophobic protective film 130 remains only on the exposed surface of the dielectric layer 112. [

Next, as shown in FIGS. 4 and 8, a plating layer 124 is formed on the coating layer 122.

The plating layer 124 is formed by dipping a ceramic body 110 having a coating layer 122 and a hydrophobic protective layer 130 on a plating solution to selectively form tin (Sn), nickel (Ni), copper Cu) or the like and then sintered at a temperature of approximately 700 ° C to 900 ° C to form a sintered metal plating film.

A pair of external electrodes 120 composed of a coating layer 122 and a plating layer 124 are formed on both ends of the ceramic body 110 and a pair of external electrodes 120 formed on the surface of the dielectric layer 112 exposed between the pair of external electrodes 120 The multilayer ceramic capacitor 100 composed of the hydrophobic protective film 130 is completed.

Example

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

The contents not described here are sufficiently technically inferior to those skilled in the art, and a description thereof will be omitted.

One. Manufacture of specimens

Examples 1 to 8

A plasma treatment was carried out under the conditions shown in Table 1, followed by polishing. Thus, a multilayer ceramic capacitor in which a CF ₂ layer having a thickness of 1 to 2 탆 was coated on the surface of a dielectric layer of a ceramic body exposed between a pair of external electrodes was fabricated.

During the plasma treatment, a 150 W RF power source and a C ₃ F ₆ gas having a flow rate of 200 sccm were used.

Comparative Example 1

A conventional multilayer ceramic capacitor without CF ₂ layer formed by plasma treatment was used on the surface of the ceramic body.

Comparative Example 2

The rest was performed in the same manner as in Examples 1 to 8 except that the plasma treatment time was set to 3 seconds.

1608size (1.6 mm x 0.8 mm x 0.8 mm), 2 pF, and 50 V (model name: 10C221JB8GNN) were used as the multilayer ceramic capacitors of Examples 1 to 8 and Comparative Examples 1 and 2.

2. Property evaluation

The IR evaluation results of each of the ten specimens prepared according to Examples 1 to 8 and Comparative Examples 1 and 2 are shown in Table 1, and ESD analysis was carried out to compare the ten specimens prepared according to Examples 1 to 8 and Comparative Examples 1 and 2 measuring the fluorine content of any of CF ₂ layer to selected ones of the results are shown in Table 2. At this time, the IR evaluation was performed at a temperature of 32 DEG C and a humidity of 80%.

Referring to Tables 1 and 2, the specimens prepared according to Examples 1 to 8 satisfied the target values of fluorine (F) in the CF ₂ layer in the range of 0.2% to 0.7% The effect of inhibiting the decrease of

On the contrary, the specimen prepared according to Comparative Example 2 in which the plasma treatment time was relatively small had a fluorine (F) content of 0.1% in the CF ₂ layer, which was much lower than the target range of 0.2% to 0.7% It was confirmed that IR deterioration occurred remarkably.

It was also confirmed that Comparative Example 1 in which the CF ₂ layer was not formed on the surface of the dielectric layer exposed by the plasma treatment did also significantly reduce the IR in a high humidity environment.

As a result, when a hydrophobic coating layer having a fluorine (F) content of 0.2% to 0.7% is provided on the surface of the dielectric layer exposed between the external electrodes of the multilayer ceramic capacitor, the IR drop is prevented in a high humidity environment, Can be improved.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, and that various changes, substitutions and alterations can be made therein without departing from the spirit and scope of the invention. However, it should be understood that such substitutions, changes, and the like fall within the scope of the following claims.

100: Multilayer Ceramic Capacitor 110: Ceramic Body
112: dielectric layer 114: internal electrode
120: external electrode 122: coating layer
124: Plating layer 130: Hydrophobic protective film

Claims (7)

A multilayer ceramic capacitor including a ceramic body and an external electrode,
Wherein a hydrophobic protective film having a content of fluorine (F) of 0.2% to 0.7% is formed on a surface of the ceramic body exposed between the external electrodes.
The method according to claim 1,
The hydrophobic protective film
A multilayer ceramic capacitor formed by a fluorocarbon-based compound.
3. The method of claim 2,
The fluorocarbon compound
CF ^{2 -} , CF ^{3 -} , and CF ^{3 -} series compounds.
The method according to claim 1,
The hydrophobic protective film
Wherein the surface of the ceramic body is surface-modified by hydrophobic treatment.
The method according to claim 1,
The ceramic body
Wherein internal electrodes and dielectric layers are alternately laminated.
The method according to claim 1,
The outer electrode
A coating layer formed on both end surfaces of the ceramic body, and a plating layer formed on the coating layer.
A hydrophobic protective film having a fluorine (F) content of 0.2% to 0.7% formed on the surface of a ceramic body exposed between external electrodes,
Wherein the hydrophobic protective film is formed by performing a plasma treatment process for plasma treatment for 5 seconds to 30 seconds under an RF power of 150 W to 160 W and a reaction gas flow rate of 200 sccm to 300 sccm.

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