KR102118492B1 - Multi-layer ceramic capacitor and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a multilayer ceramic capacitor and a method for manufacturing the same, and according to the present invention, in a multilayer ceramic capacitor including a ceramic body and an external electrode, the content of fluorine (F) on the surface of the ceramic body exposed between the external electrodes It is characterized in that a hydrophobic protective film of 0.2% to 0.7% is formed.

Description

Multilayer ceramic capacitor and manufacturing method therefor{MULTI-LAYER CERAMIC CAPACITOR AND METHOD FOR MANUFACTURING THE SAME}

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

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

A multilayer ceramic capacitor (MLCC) among ceramic electronic components includes a plurality of ceramic dielectric sheets, an internal electrode interposed between the plurality of ceramic dielectric sheets, and an external electrode electrically connected to the internal electrode.

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

Recently, as the climatic environment becomes more and more severe, MLCC requires reliability in harsh environments (high temperature, high humidity, high pressure, high ESD, etc.), that is, insulation resistance (IR) characteristics.

Korean Patent Publication No. 10-2005-0048855

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

In addition, an object of the present invention is to provide a method of manufacturing a multilayer ceramic capacitor that can prevent the degradation of IR characteristics in a humid environment.

The purpose of the multilayer ceramic capacitor according to the present invention,

In a multilayer ceramic capacitor produced by a process of manufacturing in a green process, by a binder removal, a sintering process, and an external electrode formation process, the chip is formed by moisture collection or moisture wetting on the outer surface of the multilayer ceramic capacitor in a humid environment. It is to prevent the IR characteristics of the deterioration.

This is because the outer surface of the multilayer ceramic capacitor that has undergone 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 having a hydrophobic protective film containing fluorine (F) on the surface of the ceramic body.

At this time, from the viewpoint of preventing the degradation of IR characteristics, the hydrophobic protective film may be formed of a fluorocarbon-based compound of CF ^2- , CF ^3- and CF ^- having a fluorine (F) content of 0.2% to 0.7%.

In addition, the hydrophobic protective film having a content of fluorine (F) of 0.2% to 0.7% is plasma power treatment for 5 seconds to 30 seconds under the conditions that the RF power is 150W to 160W and the reaction gas flow rate is 200 sccm to 300 sccm. It may be formed by performing a plasma treatment process.

According to the present invention, since a hydrophobic protective film containing fluorine (F) is formed on the surface of the ceramic body, moisture collection or moisture wetting on the outer surface of the multilayer ceramic capacitor is suppressed in a humid environment, thereby preventing degradation of IR characteristics and improving chip reliability. Can be.

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. 1.
3 is a partially exploded perspective view of a ceramic sheet used for laminating the ceramic body of FIG. 1.
4 is a flowchart illustrating a manufacturing process of a multilayer ceramic capacitor according to an embodiment of the present invention.
5 to 8 is a process diagram showing a method of manufacturing a multilayer ceramic capacitor according to Figure 4,
5 is a cross-sectional view of the outer electrode coating layer formed on both ends of the ceramic body,
6 is a cross-sectional view of a hydrophobic protective film 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 of a plating layer formed on a coating layer of an external electrode.

The terminology used herein is used to describe a specific embodiment and is not intended to limit the present invention. As used herein, singular forms may include plural forms unless the context clearly indicates otherwise. Also, as used herein, “comprise” and/or “comprising” excludes the presence or addition of the mentioned shapes, numbers, steps, actions, elements, elements and/or groups. It is not.

The objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments that are associated with the accompanying drawings. In addition, it should be noted that, in addition to reference numerals to the components of each drawing in the present specification, the same components have the same numbers as possible even though they are displayed on different drawings. In addition, in the description of the present invention, when it is determined that detailed descriptions of related known technologies may unnecessarily obscure the subject matter of the present invention, detailed descriptions thereof will be omitted. In the present specification, terms such as first and second are used to distinguish one component from other components, and the component 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.

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 line I-I' of FIG. 1, and FIG. 3 is a ceramic sheet used for stacking the ceramic body of FIG. 1 Partial exploded perspective view.

1 and 2, the multilayer ceramic capacitor 100 of this embodiment includes a ceramic body 110, a pair of external electrodes 120 formed at both ends of the ceramic body 110, and a pair of external electrodes It comprises a hydrophobic (hydrophobic) protective film 130 formed on the surface of the ceramic body 110 exposed between (120).

The ceramic body 110 is a body of the multilayer ceramic capacitor 100, in which a plurality of dielectric layers 112 are stacked, and an internal electrode 114 is inserted 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 produced in the form of a sheet.

The ceramic body 110 is, for example, a plurality of ceramic green sheets made of a ferroelectric material such as barium titanate (Ceramic green sheet) is laminated, pressed and completed in a housing shape through a firing process, between adjacent ceramic sheets Is integrated so that the boundary cannot be distinguished. Accordingly, even in the drawings, each ceramic sheet is integrally illustrated.

As illustrated in FIG. 2, the internal electrode 114 is interposed between the plurality of dielectric layers 112, so that the positive electrode and the negative electrode may be alternately arranged.

In this case, the first ceramic sheet 116 in which the inner electrode 114 is formed so that one end is exposed to the outside, shown in FIG. 3, and the second inner electrode 114 is formed so that the other end opposite to the one end is exposed to the outside. The ceramic body 110 of FIG. 2 may be formed by alternately laminating and firing the ceramic sheets 118.

That is, the ceramic body 110 so that the direction of the interlayer exposed end is different A plurality of ceramic sheets on which the internal electrodes 114 are printed may be stacked and formed.

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

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

Referring to FIGS. 1 and 2 again, the 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, the end of which is exposed to the outside of the ceramic body 110, and may serve as an external terminal for electrically connecting the internal electrode 114 and the external element.

One of the pair of external electrodes 120 is connected to the inner electrode 114, one end of which is exposed to the outside of the ceramic body 110, and the other is an inner electrode of which the other end is exposed to the outside of the ceramic body 110. It is connected to 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 surface of both ends of the ceramic body 110, it may be formed of a conductive metal powder and glass frit (glass frit).

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

Glass frit is preferably added to improve the corrosion resistance of the plating solution when forming the plating layer 124, but can be omitted.

The coating layer 122 is formed of a paste in which glass frit and conductive metal powder are dispersed in an organic vehicle, and then the paste is applied to both ends of the ceramic body 110 and then formed into a thin metal film sintered through a firing process. Can be.

In this case, the organic vehicle may be an organic binder that imparts liquid properties to the paste composition, and may further include an organic solvent.

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

The plating layer 124 is a layer formed for the purpose of improving solderability when the multilayer ceramic capacitor 100 is mounted on a circuit board, and is configured on the outermost side of the external electrode 120.

The plating layer 124 may be formed of a single layer or multiple layers by using a metal having excellent solderability, for example, tin (Sn), nickel (Ni), copper (Cu), etc. from the viewpoint of improving solderability. In FIG. 2, a plating layer 124 composed of a single layer is illustrated.

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

To this end, the hydrophobic protective layer 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 passivation layer 130 is formed of a hydrophobic group having little affinity for moisture, and is a surface-modifying coating layer that surface-modifies the surface of the hydrophilic dielectric layer 112 to be hydrophobic.

For example, the hydrophobic protective film 130 is a carbon (C) at least one fluorine group (F ^-) on the introduction of atoms ^2- CF, CF ^3-, CF ^- can be formed of a fluorocarbon (fluorocarbon) in series compound, and , Any one of these can be selected.

This is because the fluorine (F) atom is a material having high hydrophobicity, and when the fluorine atom is combined with a carbon atom, it has a very chemically stable property, and thus it is possible to secure both hydrophobicity and chemical resistance.

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

As such, when the hydrophobic protective film 130 having a hydrophobic group is interposed on the surface of the exposed dielectric layer 112 between the pair of external electrodes 120, the surface of the dielectric layer 112 is hydrophobic by a fluorine atom having low affinity with moisture. Modified by, moisture capture or moisture wetting on the exposed surface of the dielectric layer 112 can be suppressed.

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

At this time, if the content of fluorine (F) is less than 0.2%, the effect of preventing moisture collection or moisture wetting may be insufficient, whereas if it exceeds 0.7%, it may lead to an increase in material cost without further effect improvement.

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

The multilayer ceramic capacitor 100 configured as described above is formed by forming a hydrophobic protective film 130 containing fluorine (F) on the surface of the exposed dielectric layer 112 between the external electrodes 120, thereby forming the outer surface of the multilayer ceramic capacitor 100. Moisture trapping or moisture wetting in can be suppressed. Accordingly, the degradation of the IR characteristics of the multilayer ceramic capacitor 100 in a humid environment is prevented, thereby improving chip reliability.

Looking at the manufacturing method for the multilayer ceramic capacitor of the present embodiment configured as described above is as follows.

The method of manufacturing the multilayer ceramic capacitor of this embodiment describes the embodiment illustrated in FIG. 1, and materials such as the dielectric layer 112, the inner electrode 114, the outer electrode 120, and the hydrophobic protective film 130 are as described above. Since it is the same, duplicate description will be omitted.

4 is a flow chart showing a manufacturing process of a multilayer ceramic capacitor according to an embodiment of the present invention, FIGS. 5 to 8 are process diagrams showing a manufacturing method of the multilayer ceramic capacitor according to FIG. 4, FIG. A cross-section of a coating layer of an external electrode is formed at both ends, FIG. 6 is a cross-sectional view of a hydrophobic protective film formed on a coating layer of an external electrode and an exposed ceramic body, FIG. 7 is a cross-sectional view of a polished hydrophobic protective film, and FIG. 8 is a coating layer of an external electrode It is a sectional view in which a plating layer is formed.

4 and 5, in the manufacturing method of the multilayer ceramic capacitor of this embodiment, first, a ceramic body 110 having a coating layer 122 for external electrodes formed at both ends is prepared.

The ceramic body 110 prepares a plurality of ceramic green sheets for constituting the dielectric layer 112, and then prints the inner electrodes 114 to change the direction of the interlayer exposed end on each ceramic green sheet, and then prints the inner electrodes A plurality of ceramic green sheets printed with 114 may be laminated, pressurized, and fired at a temperature of approximately 1000°C to 1300°C to form the sintered ceramic sheet and the internal electrode 114 of the sintered metal thin film.

At this time, the plurality of ceramic green sheets may be prepared in a sheet form having a thickness of several mm by preparing a slurry by mixing ceramic powder, a binder, and a solvent, and applying the slurry on a carrier film using a doctor blade method or the like and drying the slurry. .

The internal electrode 114 may be formed by mixing a metal powder, a binder, and a solvent to prepare a metal paste, and applying the metal paste on one surface of a ceramic green sheet by a doctor blade method or the like, followed by firing.

The coating layer 122 for the external electrode is prepared by mixing a metal powder, a binder, and a solvent to prepare a metal paste, and after applying the metal paste to both ends of the ceramic body 110 by a doctor blade method, the temperature is approximately 700°C to 900°C. It can be fired in 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 coating layer 122 of the external electrode 120 and the exposed surface of the ceramic body 110.

The hydrophobic protective film 130 may be formed through a known plasma treatment process, and the reaction gas used to treat the surface of the dielectric layer 112 as hydrophobic is CF ₃ , CF ₄ , C ₂ F ₆ , C ₃ F ₆ , C ₄ F ₈ and mixtures thereof, any one of fluorocarbon gases may be used.

CF ² , CF ³ , CF ^- having a certain thickness of hydrophobicity on the exposed surface of the coating layer 122 of the external electrode 120 and the ceramic body 110 by a plasma treatment process using fluorocarbon gas as a reaction gas As the hydrophobic protective film 130 made of a fluorocarbon-based compound is formed, the surface of the dielectric layer 112 exhibiting hydrophilic properties is modified to be hydrophobic.

In the plasma treatment process, it is preferable to control process parameters such as radio frequency (RF) power, plasma treatment time, and 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 150W to 160W and a reaction gas flow rate in the range of 200sccm to 300sccm are used, the plasma treatment time may be at least 5 seconds or more, preferably 5 seconds to 30 seconds. At this time, if the plasma treatment time is less than 5 seconds, the thickness of the film is too thin to cause IR degradation of the chip, and if it exceeds 30 seconds, the IR degradation of the chip is improved, but unnecessary working 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 when the coating layer 122 is covered with the hydrophobic protective layer 130, it is difficult to form a plating layer on the coating layer 122 to improve solderability.

The process of removing the hydrophobic protective film 130 corresponding to the coating layer 122 may be performed through grinding to remove unnecessary films.

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

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

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

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

Example

Hereinafter, the configuration and operation of the present invention through a preferred embodiment of the present invention will be described in more detail. However, this is provided as a preferred example of the present invention and cannot be interpreted as limiting the present invention by any means.

The contents not described here will be sufficiently technically inferred by those skilled in the art, and thus the description thereof will be omitted.

One. Preparation of specimen

Examples 1 to 8

After performing plasma treatment under the conditions described in Table 1, polishing was performed to prepare a multilayer ceramic capacitor coated with a CF ₂ layer having a thickness of 1 to 2 μm on the surface of the dielectric layer of the ceramic body exposed between the pair of external electrodes.

At this time, a 150W RF power supply and a C ₃ F ₆ gas having a flow rate of 200 sccm were used for plasma treatment.

Comparative Example 1

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

Comparative Example 2

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

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

2. Property evaluation

Table 1 shows IR evaluation results of 10 specimens prepared according to Examples 1 to 8 and Comparative Examples 1 to 2, and 10 specimens prepared according to Examples 1 to 8 and Comparative Examples 1 to 2 by ESD analysis. The fluorine content of any one of the CF ₂ layers selected was measured and the results are shown in Table 2. At this time, the IR evaluation was measured at a temperature of 32°C and a humidity of 80%.

Referring to Table 1 and Table 2, all the specimens prepared according to Examples 1 to 8 satisfy the target range of 0.2% to 0.7%, the content of fluorine (F) in the CF ₂ layer, and the IR value in a humid environment. It was confirmed that the effect of preventing the degradation.

On the other hand, the specimen prepared according to Comparative Example 2, which has a relatively low plasma treatment time, has a content of fluorine (F) in the CF ₂ layer of 0.1%, significantly lower than the target range of 0.2% to 0.7%, and in a humid environment. It was confirmed that IR deterioration occurred remarkably.

In addition, Comparative Example 1, in which the CF ₂ layer was not formed on the surface of the dielectric layer exposed by the plasma untreatment, was also confirmed to have a significant reduction in IR in a humid environment.

As a result, when a hydrophobic coating layer having a fluorine (F) content of 0.2% to 0.7% is interposed on the surface of the dielectric layer exposed between the external electrodes of the multilayer ceramic capacitor, the reliability of the chip is prevented by preventing IR deterioration in a humid environment. Can be improved.

The preferred embodiments of the present invention described above are disclosed for the purpose of illustration, and various substitutions, modifications and changes within the scope of the technical spirit of the present invention to those skilled in the art to which the present invention pertains This will be possible, but such substitution, modification, etc. should be regarded as belonging to 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)

In the multilayer ceramic capacitor comprising a ceramic body and an external electrode,
A hydrophobic protective film having a content of fluorine (F) of 0.2% to 0.7% is formed on the surface of the ceramic body exposed between the external electrodes,
The hydrophobic protective layer is disposed on the exposed surface of the ceramic body, CF ₂ ^-, CF ₃ ^- and CF ^- The multilayer ceramic capacitor is formed of any one fluorocarbon (fluorocarbon) compounds selected among the compounds of the series.
delete delete According to claim 1,
The hydrophobic protective film
A multilayer ceramic capacitor that hydrophobically modifies the surface of the ceramic body.
According to claim 1,
The ceramic body
A multilayer ceramic capacitor formed by alternately stacking internal electrodes and dielectric layers.
According to claim 1,
The external electrode
A multilayer ceramic capacitor comprising a coating layer formed on the surface of both ends of the ceramic body and a plating layer formed on the coating layer.
A method of manufacturing a multilayer ceramic capacitor in which a hydrophobic protective film having an amount of fluorine (F) of 0.2% to 0.7% is formed on a surface of a ceramic body exposed between external electrodes,
The hydrophobic protective layer is CF ₂ ^-, CF ₃ ^- and CF ^- is formed by the fluorocarbon (fluorocarbon) compounds any of the selected ones of the compound series, and the RF power 150W to 160W, the conditions the reaction gas flow rate was 200sccm to 300sccm Under, it is formed by performing a plasma treatment process for performing plasma treatment for 5 seconds to 30 seconds,
And removing the hydrophobic protective film corresponding to the external electrode after the plasma treatment process.

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