Multilayer ceramic capacitor and board having the same

A multilayer ceramic capacitor includes a ceramic body having a plurality of dielectric layers stacked therein, and first and second internal electrodes alternately disposed with at least one among the plurality of dielectric layers interposed therebetween. The first internal electrodes include first and second lead portions exposed to a mounting surface of the ceramic body, and disposed to be spaced apart from each other in a length direction of the ceramic body. The second internal electrodes include a third lead portion exposed to the mounting surface of the ceramic body, and disposed between the first and second lead portions in the length direction of the ceramic body.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Korean Patent Application No. 10-2015-0120145, filed on Aug. 26, 2015 with the Korean Intellectual Property Office, the entirety of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a multilayer ceramic capacitor and a board having the same.

BACKGROUND

In accordance with the recent trend towards miniaturization and increased levels of capacitance in electronic products, demand has increased for electronic components used in electronic products having a small size and high capacitance.

When the equivalent series inductance (hereinafter referred to as “ESL”) of a multilayer ceramic capacitor increases, the performance of the electronic product incorporating the multilayer ceramic capacitor may deteriorate. In addition, in accordance with the miniaturization and increased capacitance of the applied electronic component, an increase in ESL of the multilayer ceramic capacitor may more significantly deteriorate the performance of the electronic product.

Particularly, in accordance with an increase in performance of integrated circuits (ICs), decoupling capacitors have increasingly been used. Therefore, demand for multilayer ceramic capacitors (MLCCs) having a three-terminal vertical multilayer structure, so-called “low inductance chip capacitors (LICC)”, capable of decreasing inductance in capacitors by decreasing a distance between external terminals to decrease a current flow path, has increased.

SUMMARY

An aspect of the present inventive concept provides a multilayer ceramic capacitor having increased capacitance with significantly reduced ESL characteristics, and a board having the same.

Another aspect of the present inventive concept provides a multilayer ceramic capacitor having a three-terminal vertical multilayer structure in which external electrodes are disposed on a mounting surface of a ceramic body to be spaced apart from each other, internal electrodes being extended to be exposed to a surface opposing the mounting surface of the ceramic body, an insulating layer being formed on the surface opposing the mounting surface of the ceramic body, and a board having the same.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present inventive concept will be described as follows with reference to the attached drawings.

Spatially relative terms, such as “above,” “upper,” “below,” and “lower” and the like, may be used herein for ease of description to describe one element's relationship to another element(s) as shown in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, elements described as “upper,” or “above” other elements would then be oriented “lower,” or “below” the other elements or features. Thus, the term “above” can encompass both the above and below orientations depending on a particular direction of the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may be interpreted accordingly.

Hereinafter, embodiments of the present inventive concept will be described with reference to schematic views illustrating embodiments of the present inventive concept. In the drawings, for example, due to manufacturing techniques and/or tolerances, modifications of the shape shown may be estimated. Thus, embodiments of the present inventive concept should not be construed as being limited to the particular shapes of regions shown herein, for example, to include a change in shape results in manufacturing. The following embodiments may also be constituted by one or a combination thereof.

The contents of the present inventive concept described below may have a variety of configurations and propose only a required configuration herein, but are not limited thereto.

Directions of a hexahedron will be defined in order to clearly describe exemplary embodiments in the present inventive concept. L, W and T shown inFIG. 1refer to a length direction, a width direction, and a thickness direction, respectively. Here, the width direction may be used to have the same concept as a direction in which dielectric layers are stacked.

Multilayer Ceramic Capacitor

FIG. 1AandFIG. 1Bare perspective views schematically illustrating a multilayer ceramic capacitor according to an exemplary embodiment of the present inventive concept.FIG. 2is a perspective view illustrating a ceramic body of the multilayer ceramic capacitor ofFIG. 1Ain a state in which the ceramic body is inverted.FIG. 3is a separate perspective view schematically illustrating a stacked structure of internal electrodes in the multilayer ceramic capacitor ofFIG. 1A. FIG.4A andFIG. 4Bare cross-sectional views respectively illustrating the multilayer ceramic capacitor ofFIG. 1A.

Referring toFIGS. 1A through 4B, a multilayer ceramic capacitor100according to the exemplary embodiment may include a ceramic body110in which a plurality of dielectric layers111are stacked in the width direction, an active region including a plurality of first and second internal electrodes121and122, first, second and third external electrodes131,132and133, and an insulating layer150.

The multilayer ceramic capacitor100according to the exemplary embodiment may be a three-terminal vertical multilayer capacitor having a total of three external terminals and including internal electrodes stacked therein and disposed perpendicularly with respect to amounting surface of a board.

The ceramic body110may have first and second surfaces S1and S2opposing each other in the thickness direction, third and fourth surfaces S3and S4connecting the first and second surfaces S1and S2and opposing each other in the length direction, and fifth and sixth surfaces S5and S6opposing each other in the width direction.

Hereinafter, in the exemplary embodiment, a mounting surface of the multilayer ceramic capacitor100may be the first surface S1of the ceramic body110.

The ceramic body110as described above may be formed by stacking the plurality of dielectric layers111in the width direction and then sintering the stacked dielectric layers111, and a shape thereof is not particularly limited, but may be a hexahedral shape as illustrated in the accompanying drawings.

The plurality of dielectric layers111configuring the ceramic body110may be in a sintered state, and boundaries between dielectric layers111adjacent to each other may be integrated such that they may not be readily discernible without the use of a scanning electron microscope (SEM).

The dielectric layers111may contain a ceramic powder having high permittivity, for example, a barium titanate (BaTiO3)-based powder or a strontium titanate (SrTiO3) based powder, or the like, but the present inventive concept is not limited thereto as long as sufficient capacitance may be obtained.

Furthermore, in addition to the ceramic powder, a ceramic additive, an organic solvent, a plasticizer, a binder, a dispersant, and the like, may be further added to the dielectric layers111.

The ceramic body110as described above may include the active region having the plurality of internal electrodes therein, as a part contributing to capacitance formation of the capacitor, and cover layers112and113formed on both side surfaces of the active region, respectively, as margin parts in the width direction.

The active region may be formed by repeatedly stacking the plurality of first and second internal electrodes121and122with the respective dielectric layers111interposed therebetween.

The cover layers112and113may have the same material and configuration as those of the dielectric layers111except that internal electrodes are not included therein.

The cover layers112and113may be formed by stacking a single dielectric layer or at least two dielectric layers on both side surfaces of the active region in the width direction, respectively, and may generally serve to prevent the first and second internal electrodes121and122from being damaged by physical or chemical stress.

The first and second internal electrodes121and122, electrodes having different polarities, may be formed in the ceramic body110and disposed to face each other, with respective dielectric layers111interposed therebetween.

The first and second internal electrodes121and122may be electrically insulated from each other by the dielectric layers111disposed therebetween.

In addition, the first and second internal electrodes121and122may be disposed to be spaced apart from the third and fourth surfaces S3and S4of the ceramic body110by a predetermined distance in order to prevent the infiltration of an external foreign substance and to increase reliability.

In addition, a material for forming the first and second internal electrodes121and122is not particularly limited. For example, the first and second internal electrodes121and122may be formed using a conductive paste formed of at least one of a noble metal material such as palladium (Pd), a palladium-silver (Pd—Ag) alloy, or the like, nickel (Ni), and copper (Cu).

Further, as a method of printing the conductive paste, a screen printing method, a gravure printing method, or the like, may be used, but the present inventive concept is not limited thereto.

The first and second internal electrodes121and122may include first and second body portions121aand122aoverlapping the internal electrodes adjacent thereto to contribute to capacitance formation, and first and second lead portions121band121b′ and a third lead portion122b, regions formed by increasing widths of portions of the first and second body portions121aand122ato be extended to the mounting surface of the ceramic body110.

Upper ends of the first and second body portions121aand122amay be extended to be exposed to upper surfaces of the dielectric layers111. That is, the first and second internal electrodes121and122may be structured to be exposed to the second surface S2of the ceramic body110.

According to such a structure, an area of overlap of the first and second internal electrodes121and122may be further increased, thereby leading to an increase in capacitance of the multilayer ceramic capacitor100.

In addition, when the upper ends of the first and second body portions121aand122aare exposed to upper surfaces of the dielectric layers111, a debinder path may be increased to improve reliability.

End portions of the first and second lead portions121band121b′ and the third lead portion122bmay be externally exposed to the mounting surface of the ceramic body110.

In addition, lengths of the first and second lead portions121band121b′ and the third lead portion122bare not limited, but may have lengths shorter than those of the first and second body portions121aand122ain the thickness direction in order to increase capacitance.

In the exemplary embodiment, the first and second lead portions121band121b′ may be disposed to be spaced apart from each other in the length direction of the ceramic body110, and may be extended from the first body portion121aof the first internal electrode121to be exposed to the first surface S1, the mounting surface of the ceramic body110.

The third lead portion122bmay be disposed between the first and second lead portions121band121b′, and may be extended from the second body portion122aof the second internal electrode122to be exposed to the first surface S1of the ceramic body110.

The first and second external electrodes131and132, electrodes having the same polarity as each other, may be disposed on the first surface S1of the ceramic body110to be spaced apart from each other in the length direction of the ceramic body110, and may come into contact with the first and second lead portions121band121b′ exposed to the first surface S1of the ceramic body110, respectively, to thereby be electrically connected thereto.

The first and second external electrodes131and132may be formed to be extended from the first surface S1of the ceramic body110to portions of the fifth and sixth surfaces S5and S6of the ceramic body110in the width direction so as to improve adhesion strength.

In addition, as illustrated inFIG. 1B, first and second external electrodes131′ and132′ may be formed to be extended from the first surface S1of the ceramic body110to portions of the third and fourth surfaces S3and S4of the ceramic body110in the length direction, respectively, in order to improve adhesion strength and to increase electrical connectivity when the capacitor is mounted on a board.

The third external electrode133, an electrode having a different polarity from that of the first and second external electrodes131and132, may be used as a ground terminal in the exemplary embodiment.

The third external electrode133may be disposed between the first and second external electrodes131and132and come into contact with the third lead portion122bexposed to the first surface S1of the ceramic body110to thereby be electrically connected thereto.

The third external electrode133may be extended from the first surface S1of the ceramic body110to portions of the fifth and sixth surfaces S5and S6of the ceramic body110in the width direction so as to improve adhesion strength.

In a two-terminal multilayer ceramic capacitor, since external electrodes may be disposed on both opposing surfaces of a ceramic body in a length direction and a current path may be relatively long when an alternating current signal is applied to the external electrodes, a current loop may be further increased and the magnitude of induced magnetic field may be higher, thereby leading to defects such as an increase in inductance.

In the exemplary embodiment, the first, second and third external electrodes131,132and133may be disposed on the first surface S1, the mounting surface of the ceramic body110in the thickness direction, whereby a current path may be decreased when an alternating current signal is applied to the external electrodes to shorten a current loop, and accordingly, the magnitude of induced magnetic field may be decreased to result in a decrease in inductance (ESL) of the capacitor.

In the exemplary embodiments, widths of the first to third lead portions121b,121b′ and122bmay be formed narrower than those of the first to third external electrodes131,132and133.

That is, according to such a structure, all portions of the first to third lead portions121b,121b′ and122bexposed to the first surface S1of the ceramic body110may be covered by the first, second and third external electrodes131,132and133, whereby defects such as short circuits between the internal electrodes, deteriorations in moisture resistance properties due to external foreign substances, or the occurrence of short circuits may be prevented.

Meanwhile, the first, second and third external electrodes131,132and133according to the exemplary embodiment may include conductive layers and plating layers.

For example, the first, second and third external electrodes131,132and133may include first, second and third conductive layers131a,132a, and133acoming into contact with the lead portions of the internal electrodes disposed in positions corresponding to the conductive layers, respectively, to thereby be connected thereto, first, second and third nickel (Ni) plating layers131b,132b, and133bformed to cover the first to third conductive layers131a,132a, and133a, and first, second and third tin (Sn) plating layers131c,132c, and133cformed to cover the first, second and third nickel plating layers131b,132b, and133b.

In this case, the first, second and third conductive layers131a,132a, and133amay be formed of the same conductive material as that of the first and second internal electrodes121and122.

However, the present inventive concept is not limited thereto. For example, the first, second and third conductive layers131a,132a, and133amay be formed using powder particles of a metal such as copper (Cu), silver (Ag), nickel (Ni), and the like, and may be formed by applying a conductive paste prepared by adding a glass frit to the metal powder particles and then sintering the applied conductive paste.

The insulating layer150may be disposed on the second surface S2opposing the mounting surface of the ceramic body110, and may cover exposed portions of the first and second body portions121aand122aof the first and second internal electrodes121and122exposed to the second surface S2opposing the mounting surface of the ceramic body110, thereby preventing defects such as short circuits between the internal electrodes, deterioration in moisture resistance properties due to external foreign substances, or the occurrence of short circuits.

The insulating layer150may be formed of an insulating material such as epoxy or a ceramic slurry, but the present inventive concept is not limited thereto.

In addition, the insulating layer150may reduce chipping defects of the ceramic body, capable of occurring in a manufacturing process.

In addition, when the multilayer ceramic capacitor is lifted by bringing a nozzle into contact with an upper surface of the ceramic body in order to use the multilayer ceramic capacitor, the insulating layer150may decrease the influence of impacts when the nozzle contacts the ceramic body to thereby improve the durability of a product.

Modified Examples

FIG. 5is a perspective view schematically illustrating a multilayer ceramic capacitor according to another exemplary embodiment of the present inventive concept.FIG. 6AandFIG. 6Bare plan views schematically illustrating structures of first and second internal electrodes in the multilayer ceramic capacitor ofFIG. 5.FIG. 7AandFIG. 7Bare cross-sectional views respectively illustrating the multilayer ceramic capacitor ofFIG. 5.

A detailed description of the same structure as that in the above-mentioned exemplary embodiment will be omitted in order to avoid an overlapping description, and first and second lead portions21band21b′ of a first internal electrode21, a third lead portion22bof a second internal electrode22, and first and second insulating parts141and142having different structures from those in the above-mentioned exemplary embodiment will be described in detail.

Referring toFIG. 5throughFIG. 7B, in a multilayer ceramic capacitor100′ according to the exemplary embodiment of the present inventive concept, the first internal electrode21may include a first body portion21aand the first and second lead portions21band21b′ extending from the first body portion21ato be exposed to a first surface S1of a ceramic body110′, and portions of the first and second lead portions21band21b′ exposed outwardly of the ceramic body110′ may not be covered by the first and second external electrodes131and132and may be exposed to the first surface S1of the ceramic body110′.

In addition, the second internal electrode22may include a second body portion22aand the third lead portion22bextending from the second body portion22ato be exposed to the first surface S1of the ceramic body110′, and a portion of the third lead portion22bexposed outwardly of the ceramic body110′ may not be covered by the third electrode133and may be exposed to the first surface S1of the ceramic body110′.

In addition, the first and second insulating parts141and142may be disposed on the first surface S1of the ceramic body110′ so as to cover the portions of the first, second and third lead portions21b,21b′ and22bthat are not covered by the first, second and third external electrodes131,132and133and are exposed to the first surface S1of the ceramic body110′.

The first and second insulating parts141and142may be formed of an insulating material such as epoxy or ceramic slurry, but the present inventive concept is not limited thereto.

In this case, the first insulating part141may be disposed between the first and third external electrodes131and133on the first surface S1of the ceramic body110′, and the second insulating part142may be disposed between the second and third external electrodes132and133on the first surface S1of the ceramic body110′.

The first and second insulating parts141and142may cover all of the exposed portions of the first to third lead portions21b,21b′ and22bto thereby prevent defects in which portions of the first to third lead portions21b,21b′ and22bare exposed outwardly of the ceramic body110′ to cause short circuits between the lead portions, deterioration in moisture resistance properties due to external foreign substances, or the occurrence of short circuits.

The first and second insulating parts141and142may be formed to be extended from the first surface S1of the ceramic body110′ to portions of the fifth and sixth surfaces S5and S6of the ceramic body110′ in the width direction so as to improve adhesion strength.

FIG. 8is a perspective view schematically illustrating a multilayer ceramic capacitor according to another exemplary embodiment of the present inventive concept.FIG. 9AandFIG. 9Bare plan views schematically illustrating structures of first and second internal electrodes in the multilayer ceramic capacitor ofFIG. 8.FIG. 10AandFIG. 10Bare cross-sectional views respectively illustrating the multilayer ceramic capacitor ofFIG. 8.

A detailed description of the same structure as that in the above-mentioned exemplary embodiment will be omitted in order to avoid an overlapping description, and first and second lead portions1210band1210b′ of a first internal electrode1210and a third lead portion1220bof a second internal electrode1220having different structures from those in the above-mentioned exemplary embodiment will be described in detail.

Referring toFIG. 8throughFIG. 10B, in a multilayer ceramic capacitor1000according to the exemplary embodiment of the present inventive concept, the first internal electrode1210may include a first body portion1210aand first and second lead portions1210band1210b′ extended from the first body portion1210ato be exposed to a first surface S1of a ceramic body1110. Portions of the first and second lead portions1210band1210b′ exposed outwardly of the ceramic body1110may not be covered by the first and second external electrodes131and132and may be exposed to the first surface S1of the ceramic body1110.

In addition, the second internal electrode1220may include a second body portion1220aand the third lead portion1220bextended from the second body portion1220ato be exposed to the first surface S1of the ceramic body1110, and a portion of the third lead portion1220bexposed outwardly of the ceramic body1110may not be covered by the third electrode133and may be exposed to the first surface S1of the ceramic body1110.

In addition, the first and second insulating parts141and142may be disposed on the first surface S1of the ceramic body1110so as to cover the portions of the first, second and third lead portions1210b,1210b′ and1220bthat are not covered by the first, second and third external electrodes131,132and133and are exposed to the first surface S1of the ceramic body1110.

However, in the exemplary embodiment ofFIG. 5throughFIG. 7B, a gap MW1between the first and second lead portions21band21b′ may be formed to be greater than a length EW1of the third lead portion22b, and accordingly, the first and second lead portions21band21b′ and the third lead portion22bmay not overlap each other in a direction in which the first and second internal electrodes21and22are stacked.

In the exemplary embodiment ofFIG. 8throughFIG. 10B, a gap MW2between the first and second lead portions1210band1210b′ may be formed to be narrower than a length EW2of the third lead portion1220b.

Accordingly, portions of the first and second lead portions1210band1210b′ and a portion of the third lead portion1220bmay overlap each other in a direction in which the first and second internal electrodes1210and1220are stacked, whereby the overall area of overlap of the first and second internal electrodes1210and1220may be increased, thereby leading to an increase in capacitance of the multilayer ceramic capacitor1000.

Board Having Multilayer Ceramic Capacitor

FIG. 11is a perspective view illustrating an exemplary embodiment in which the multilayer ceramic capacitor ofFIG. 1Ais mounted on a board.FIG. 12is a cross-sectional view ofFIG. 11.

Referring toFIGS. 11 and 12, a board200having a multilayer ceramic capacitor according to the exemplary embodiment may include a substrate210on which the multilayer ceramic capacitor100is mounted and first, second and third electrode pads221,222and223formed on an upper surface of the substrate210to be spaced apart from one another.

In this case, the multilayer ceramic capacitor100may be electrically connected to the substrate210by soldering portions230in a state in which first, second and third external electrodes131,132, and133are respectively positioned on the first, second and third electrode pads221,222and223to come into contact therewith.

Although the case in which the multilayer ceramic capacitor ofFIG. 1Ais mounted is described in the exemplary embodiment, the present inventive concept is not limited thereto. For example, the multilayer ceramic capacitor shown inFIG. 1B,FIG. 5orFIG. 8may be mounted on a board in a similar manner to the above case, such that boards having a multilayer ceramic capacitor may be configured.

As set forth above, according to exemplary embodiments of the present inventive concept, ESL characteristics may be reduced by a three-terminal vertical multilayer structure, and an area of overlap of the first and second internal electrodes may be increased to thereby allow for an increase in capacitance of the multilayer ceramic capacitor.

While exemplary embodiments have been shown and described above, it will be apparent to those skilled in the art that modifications and variations could be made without departing from the scope of the invention as defined by the appended claims.