Multilayer ceramic capacitor

A multilayer ceramic capacitor may include a ceramic body having a plurality of dielectric layers; first and second internal electrodes disposed in the ceramic body to be alternately exposed to the first and second end surfaces of the ceramic body, having the dielectric layers interposed therebetween; and first and second external electrodes electrically connected to the first and second internal electrodes, respectively. The first and second external electrodes may include: first and second internal conductive layers; first and second insulating layers; and first and second external conductive layers.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No. 10-2013-0133450 filed on Nov. 5, 2013, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND

The present disclosure relates to a multilayer ceramic capacitor.

As electronic components using a ceramic material, there are a capacitor, an inductor, a piezoelectric element, a varistor, a thermistor, and the like.

Among these ceramic electronic components, a multilayer ceramic capacitor (MLCC) is an electronic component having advantages such as miniaturization, high capacity, and easiness of mounting.

The multilayer ceramic capacitor is a chip shaped condenser mounted on circuit boards of various electronic products such as a display device, for example, a liquid crystal display (LCD), a plasma display panel (PDP), or the like, a computer, a personal digital assistants (PDA), a mobile phone, and the like, to serve to charge electricity or discharge electricity.

Recently, due to an increase in a size of display devices, an increase in a speed of a central processing unit (CPU), or the like, a severe heat generation defect has occurred in the electronic device.

Therefore, in the multilayer ceramic capacitor, the securing of sufficient capacitance and reliability is required even at a high temperature for a stable operation of an integrated circuit (IC) installed in the electronic device.

Such a multilayer ceramic capacitor may have a structure in which a plurality of dielectric layers are stacked while internal electrodes having different polarities are alternately disposed with the respective dielectric layers interposed therebetween.

In this case, since the dielectric layers have piezoelectricity, when direct current (DC) or alternate current (AC) voltage is applied to the multilayer ceramic capacitor, a piezoelectric phenomenon is generated between the internal electrodes, thereby generating periodic vibrations while a volume of a ceramic body is expanded and contracted according to a frequency.

The vibrations are transferred to a printed circuit board through an external electrode of the multilayer ceramic capacitor and a soldering material connecting the external electrode to the printed circuit board at the time of mounting the multilayer ceramic capacitor on the board, such that the entire printed circuit board may become an acoustic reflective surface to generate a vibration sound, which is noise.

This vibration sound may have a frequency corresponding to an audio frequency in a region of 20 to 20,000 Hz, which may cause listener discomfort and is referred to as acoustic noise.

Recently, in electronic devices, since acoustic noise generated in the multilayer ceramic capacitor as described above may become prominent due to a noise reduction of components, research into a technology of effectively decreasing acoustic noise generated in the multilayer ceramic capacitor has been required.

As a method of decreasing acoustic noise, a method of attaching a metal terminal having a frame shape to both end surface of a multilayer ceramic capacitor to thereby mount the multilayer ceramic capacitor so as to be spaced apart from a printed circuit board by a predetermined interval has been disclosed.

However, in order to decrease the acoustic noise to a predetermined level using the metal terminal, a height of the metal terminal needs to be increased to a level more than a predetermined standard.

In this case, since an increase in the height of the metal terminal may increase a height of a component in which the multilayer ceramic capacitor is mounted, thereby leading to an inability to be used in a product having a height limitation.

SUMMARY

An exemplary embodiment of the present disclosure may provide a multilayer ceramic capacitor capable of effectively reducing acoustic noise generated due to vibrations being transferred to a printed circuit board, the vibrations being generated by a piezoelectric phenomenon in the multilayer ceramic capacitor.

According to an exemplary embodiment of the present disclosure, a multilayer ceramic capacitor may include: a ceramic body including a plurality of dielectric layers and having first and second main surfaces opposing each other in a thickness direction, first and second end surfaces opposing each other in a length direction, and first and second side surfaces opposing each other in a width direction; a plurality of first and second internal electrodes disposed in the ceramic body to be alternately exposed to the first and second end surfaces of the ceramic body, having the dielectric layers interposed therebetween; and first and second external electrodes electrically connected to the first and second internal electrodes, respectively, wherein the first and second external electrodes includes: first and second internal conductive layers extended from the first and second end surfaces of the ceramic body to portions of the first main surface, respectively; first and second insulating layers extended from the first and second internal conductive layers on the first and second end surfaces to portions of the first and second internal conductive layers on the first main surface, respectively, and having a length shorter than that of the first and second internal conductive layers in such a manner that portions of the first and second internal conductive layers are exposed to the first main surface; and first and second external conductive layers formed on the first and second internal conductive layers on the first main surface, respectively.

According to exemplary embodiment of the present disclosure, a multilayer ceramic capacitor may include: a ceramic body including a plurality of dielectric layers and having first and second main surfaces opposing each other in a thickness direction, first and second end surfaces opposing each other in a length direction, and first and second side surfaces opposing each other in a width direction; a plurality of first and second internal electrodes disposed in the ceramic body to be alternately exposed to the first and second end surfaces of the ceramic body, having the dielectric layers interposed therebetween; and first and second external electrodes electrically connected to the first and second internal electrodes, respectively, wherein the first and second external electrodes respectively includes: first and second internal conductive layers extended from the first and second end surfaces of the ceramic body to portions of the first main surface, respectively; first and second insulating layers formed on the first and second internal conductive layers on the first main surface, respectively, while having a width narrower than that of the first and second internal conductive layers so as to expose portions of the first and second internal conductive layers; and first and second external conductive layers formed on the first and second internal conductive layers on the first main surface, respectively.

The first and second external conductive layers may be simultaneously formed on the first internal conductive layer and the first insulating layer on the first main surface, and the second internal conductive layer and the second insulating layer on the first main surface, respectively.

The multilayer ceramic capacitor may further include a third insulating layer formed on the first main surface of the ceramic body to connect the first and second insulating layers to each other.

The first and second insulating layers may be extended from the first and second internal conductive layers on the first main surface to portions of the first and second end surfaces, respectively.

The first and second external conductive electrodes may be extended from the first and second internal conductive layers on the first main surface to portions of the first and second side surfaces, respectively.

The first and second insulating layers may have a thickness of 50 μm or more.

The first and second insulating layers may be formed of a material containing an insulating epoxy.

The first and second external conductive layers may be formed of a material containing a conductive epoxy.

DETAILED DESCRIPTION

The disclosure may, however, be exemplified in many different forms and should not be construed as being limited to the specific embodiments set forth herein.

Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

The present disclosure relates to a multilayer ceramic electronic component. Examples of the multilayer ceramic electronic component according to an exemplary embodiment of the present disclosure may include a multilayer ceramic capacitor, an inductor, a piezoelectric element, a varistor, a chip resistor, a thermistor, and the like. Hereinafter, a multilayer ceramic capacitor will be described as an example of the multilayer ceramic electronic component.

In addition, directions of a hexahedron will be defined in order to clearly describe exemplary embodiments of the present disclosure. L, W and T shown inFIG. 1refer to a length direction, a width direction, and a thickness direction, respectively, of the hexahedron.

Here, the thickness direction may be used to have the same concept as that of a direction in which dielectric layers are stacked.

FIG. 1is a perspective view showing a schematic structure of a multilayer ceramic capacitor according to an exemplary embodiment of the present disclosure, andFIG. 2is a cross-sectional view taken along line A-A′ ofFIG. 1.

Referring toFIGS. 1 and 2, a multilayer ceramic capacitor100according to an exemplary embodiment of the present disclosure may include a ceramic body110in which a plurality of dielectric layers111are stacked in the thickness direction, a plurality of first and second internal electrodes121and122, and first and second external electrodes electrically connected to the first and second internal electrodes121and122, respectively.

The ceramic body110may be formed by stacking the plurality of dielectric layers111and then sintering the stacked dielectric layers, and the dielectric layers111may be integrated so as not to confirm a boundary between the dielectric layers111adjacent to each other.

In addition, the ceramic body110may have a hexahedral shape.

In the exemplary embodiment, surfaces of the ceramic body110, opposing each other in the thickness direction, that is, a direction in which the dielectric layers111are stacked, may be defined as first and second main surfaces, end surfaces of the ceramic body110, connecting the first and second main surfaces to each other and opposing each other in the length direction may be defined as first and second end surfaces, and side surfaces of the ceramic body110, opposing each other in the width direction may be defined as first and second side surfaces.

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

In addition, if necessary, the dielectric layers111may further contain various types of ceramic additive such as a transition metal oxide or carbide, a rare earth element, magnesium (Mg), aluminum (Al), or the like, an organic solvent, a plasticizer, a binder, a dispersant, and the like, in addition to the ceramic powder.

The first and second internal electrodes121and122, electrodes having different polarities, may be formed and stacked on at least one surface of a ceramic sheet forming the dielectric layer111and be alternately exposed to the first and second end surfaces of the ceramic body110, having each dielectric layer111interposed therebetween in the ceramic body110.

In this case, the first and second internal electrodes121and122may be electrically insulated from each other by the dielectric layer disposed therebetween, and capacitance of the multilayer ceramic capacitor100may be in proportion to an area of an overlapped portion between the first and second internal electrodes121and122in the direction in which the dielectric layers111are stacked.

In addition, the first and second internal electrodes121and122may be formed of a conductive metal, for example, any one of silver (Ag), lead (Pb), platinum (Pt), nickel (Ni), and copper (Cu), an alloy thereof, or the like, but the present disclosure is not limited thereto.

FIG. 3is a bottom view of the multilayer ceramic capacitor according to an exemplary embodiment of the present disclosure, andFIG. 4is a cross-sectional view taken along line B-B′ ofFIG. 1.

Referring toFIGS. 3 and 4, the first and second external electrodes may include first and second internal conductive layers131and132, first and second insulating layers141and142, and first and second external conductive layers151and152.

In an exemplary embodiment, the first and second internal conductive layers131and132may be extended from the first and second end surfaces of the ceramic body110to portions of the first main surface, a mounting surface, such that the first and second internal conductive layers131and132cover the plurality of first and second internal electrodes121and122alternately exposed to the first and second end surfaces of the ceramic body to thereby be electrically connected thereto, in a cross-section of the ceramic body110in a width-thickness (W-T) direction.

Further, the first and second internal conductive layers131and132may be extended from the first and second end surfaces of the ceramic body110to portions of the second main surface or the first and second side surfaces of the ceramic body110in order to suppress moisture or a plating solution from infiltrating into the internal electrodes at the time of forming first and second plating layers to be described below.

In this case, the first and second internal conductive layers131and132may be formed using a copper-glass (Cu-glass) paste in order to provide high reliability such as excellent heat cycle resistance, moisture resistance, and the like, while having excellent electrical properties, but the present disclosure is not limited thereto.

The first and second insulating layers141and142may be formed on the first and second internal conductive layers131and132and may allow solder not to be formed or to be minimized on circumferential surfaces except for mounting surfaces of the first and second external electrodes at the time of mounting the multilayer ceramic capacitor100on a printed circuit board, or the like, as well as suppressing moisture or a plating solution from infiltrating into the internal electrodes at the time of forming first and second plating layers to be described below.

The first and second insulating layers141and142as described above may be formed on the first and second internal conductive layers131and132to be extended from the first and second end surfaces to portions of the first main surface, while having a length shorter than a length of the first and second internal conductive layers131and132formed on the first main surface in such a manner that portions of the respective first and second internal conductive layers131and132are exposed to the first main surface.

In addition, if necessary, the first and second insulating layers141and142may be extended to portions of the first and second internal conductive layers131and132on the first and second side surfaces, respectively.

In this case, the first and second insulating layers141and142may be formed using an epoxy resist having insulating properties, or the like, but the present disclosure is not limited thereto.

In addition, the first and second insulating layers141and142may be formed by one of a wheel coating method, a method of forming grooves in surfaces of the first and second internal conductive layers131and132, filling the grooves with an insulating epoxy paste, or the like, and then transferring the paste, a screen printing method, and the like.

Referring to the following Table 1, the first and second insulating layers141and142may have a thickness of 50 μm or more in a similar manner to the case of samples 3 to 7 in order to decrease a vibration sound.

The reason for this is that in the case in which the thickness of the first and second insulating layers141and142is less than 50 μm, for example, in the cases of samples 1 and 2, since a sufficient separation distance between the multilayer ceramic capacitor100and the board was not secured at the time of mounting the multilayer ceramic capacitor on a board, a vibration sound of 30 dB or more was generated, such that effects of decreasing a vibration transfer was insignificant.

The first and second external conductive layers151and152may be respectively formed on exposed portions of the first and second internal conductive layers131and132on the first main surface, and serve as external connection terminals attached to a printed circuit board or the like by solder at the time of mounting the multilayer ceramic capacitor on the printed circuit board.

In addition, the mounting surface of the multilayer ceramic capacitor100may be clearly distinguished by the first and second external conductive layers151and152, thereby protecting the multilayer ceramic capacitor100from being mounted in a vertically reversed manner.

In this case, the first and second external conductive layers151and152may be formed, for example, using a copper-epoxy (Cu-epoxy) paste, or the like, capable of absorbing mechanical stress to improve reliability while having excellent conductivity, but the present disclosure is not limited thereto.

Further, the first and second external conductive layers151and152may be simultaneously attached to the first internal conductive layer131and the first insulating layer141on the first main surface, and the second internal conductive layer132and the second insulating layer142on the first main surface, respectively.

Meanwhile, plating layers may be formed on the first and second external conductive layers151and152, respectively.

The plating layers may include a nickel (Ni) plating layer formed on the first and second external conductive layers151and152and a tin (Sn) plating layer formed on the nickel plating layer.

The plating layers may be provided to increase adhesion strength between the multilayer ceramic capacitor100and the printed circuit board at the time of mounting the multilayer ceramic capacitor100on the printed circuit board, or the like, by solder.

The first and second external electrodes configured as described above may significantly decrease a height of a solder fillet formed at the time of mounting the multilayer ceramic capacitor on the printed circuit board due to the first and second insulating layers141and142formed on the first and second end surfaces or first and second side surfaces of the ceramic body110to thereby significantly decrease vibrations transferred to the board through the solder fillet. The first and second insulating layers141and142may have flexible characteristics, such that additional effects capable of absorbing vibrations may be expected.

In addition, an interval between the multilayer ceramic capacitor100and the printed circuit board may be increased due to thicknesses of the first and second insulating layers141and142and the first and second external conductive layers151and152formed in a stepped manner on the first main surface, which is the mounting surface of the ceramic body110, thereby decreasing a vibration transfer at the time of mounting the multilayer ceramic capacitor100on the printed circuit board.

FIG. 5is a perspective view showing a schematic structure of a multilayer ceramic capacitor according to another exemplary embodiment of the present disclosure, andFIG. 6is a cross-sectional view taken along line A-A′ ofFIG. 5.

Referring toFIGS. 5 and 6, a multilayer ceramic capacitor200according to another exemplary embodiment of the present disclosure may include a ceramic body210in which a plurality of dielectric layers211are stacked in the thickness direction, a plurality of first and second internal electrodes221and222, and first and second external electrodes electrically connected to the first and second internal electrodes221and222, respectively.

Here, since structures of the ceramic body210and the first and second internal electrodes221and222are similar to those in the above-mentioned exemplary embodiment, a detailed description thereof will be omitted in order to avoid an overlapped description, and the first and second external electrodes having a different structure from that in the above-mentioned exemplary embodiment will be described in detail based on the accompanying drawings.

FIG. 7is a bottom view of the multilayer ceramic capacitor according to another exemplary embodiment of the present disclosure, andFIG. 8is a cross-sectional view taken along line B-B′ ofFIG. 5.

Referring toFIGS. 7 and 8, the first and second external electrodes may include first and second internal conductive layers231and232, first and second insulating layers241and242, and first and second external conductive layers251and252.

In this exemplary embodiment, the first and second internal conductive layers231and232may be extended from the first and second end surfaces of the ceramic body210to portions of the first main surface, a mounting surface, to cover the plurality of first and second internal electrodes221and222alternately exposed to the first and second end surfaces of the ceramic body210, thereby being electrically connected thereto, in a cross-section of the ceramic body210in a width-thickness (W-T) direction.

In addition, if necessary, the first and second internal conductive layers231and232may be formed to be extended from the first and second end surfaces of the ceramic body210to portions of the first and second side surfaces thereof.

Further, the first and second internal conductive layers231and232may be extended from the first and second end surfaces of the ceramic body210to portions of the second main surface or the first and second side surfaces of the ceramic body210in order to suppress moisture or a plating solution from infiltrating into the internal electrode at the time of forming first and second plating layers to be described below.

In this case, the first and second internal conductive layers231and232may be formed using a copper-glass (Cu-glass) paste in order to provide high reliability such as excellent heat cycle resistance, moisture resistance, and the like, while having excellent electrical properties, but the present disclosure is not limited thereto.

The first and second insulating layers241and242may be formed on the first and second internal conductive layers231and232and suppress moisture or the plating solution from infiltrating into the internal electrode at the time of forming first and second plating layers to be described below, as well as having flexible characteristics, such that additional effects capable of absorbing vibrations may be expected.

The first and second insulating layers241and242as described above may formed on the first and second internal conductive layers231and232on the first main surface, while having a width narrower than that of the first and second internal conductive layers231and232so as to expose portions of the first and second internal conductive layers231and232formed on the first main surface.

In addition, if necessary, the first and second insulating layers241and242may be formed on the first and second internal conductive layers231and232so that both end portions thereof are extended from the first main surface to portions of the first and second side surfaces, respectively.

In this case, the first and second insulating layers241and242may be formed using an epoxy resist having insulating properties, or the like, but the present disclosure is not limited thereto.

In addition, the first and second insulating layers241and242may be formed by one of a wheel coating method, a method of forming grooves in surfaces of the first and second internal conductive layers231and232, filling the grooves with an insulating epoxy paste, or the like, and then transferring the paste, a screen printing method, and the like.

Further, the first and second insulating layers241and242may have a thickness of 50 μm or more.

The reason for this is that in the case in which the thickness of the first and second insulating layers241and242is less than 50 μm, a sufficient separation distance between the multilayer ceramic capacitor200and the board was not secured at the time of mounting the multilayer ceramic capacitor on a board, such that effects of decreasing a vibration transfer may be insufficient.

Meanwhile, a third insulating layer243may be formed on the first surface of the ceramic body210to connect the first and second insulating layers241and242to each other in the length direction. In this exemplary embodiment, the first to third insulating layers241to243may configure a single insulating layer240.

The first and second external conductive layers251and252may be connected to exposed portions of the first and second internal conductive layers231and232on the first main surface, the exposed portion not being covered by the first and second insulating layers241, and may serve as external connection terminals attached to a printed circuit board, or the like by solder at the time of mounting the multilayer ceramic capacitor on the board.

In this case, the first and second external conductive layers251and252may be formed on the first main surface in the width direction of the ceramic body and be extended to portions of the first and second internal conductive layers231and232on the first and second side surfaces, respectively.

In addition, the mounting surface of the multilayer ceramic capacitor200may be clearly distinguished by the first and second external conductive layers251and252, thereby protecting the multilayer ceramic capacitor200from being mounted in a vertically reversed manner.

In this case, the first and second external conductive layers251and252may be formed, for example, using a copper-epoxy (Cu-epoxy) paste, or the like, capable of absorbing mechanical stress to improve reliability while having excellent conductivity, but the present disclosure is not limited thereto.

Further, the first and second external conductive layers251and252may be simultaneously attached to the first internal conductive layer231and the first insulating layer241on the first main surface, and the second internal conductive layer232and the second insulating layer242on the first main surface, respectively.

Meanwhile, plating layers may be formed on the respective first and second external conductive electrodes251and252.

The plating layers may include a nickel (Ni) plating layer formed on the first and second external conductive layers251and252and a tin (Sn) plating layer formed on the nickel plating layer.

The plating layers may be provided to increase adhesion strength between the multilayer ceramic capacitor200and the printed circuit board at the time of mounting the multilayer ceramic capacitor200on the printed circuit board, or the like, by solder.

The first and second external electrodes configured as described above may increase an interval between the multilayer ceramic capacitor200and the printed circuit board due to thicknesses of the first and second insulating layers241and242and the first and second external conductive layers251and252formed in a stepped manner on the first main surface, which is the mounting surface of the ceramic body210, thereby decreasing a vibration transfer at the time of mounting the multilayer ceramic capacitor200on the printed circuit board.

As set forth above, according to exemplary embodiments of the present disclosure, the interval between the multilayer ceramic capacitor and the printed circuit board may be increased at the time of mounting the multilayer ceramic capacitor on the printed circuit board due to thicknesses of the first and second insulating layers and the first and second external conductive layers formed in a stepped manner on the first main surface, which is the mounting surface of the ceramic body, such that vibrations transferred to the printed circuit board may be decreased, thereby decreasing acoustic noise.

Further, the insulating layer of the external electrode may have flexible characteristics, such that additional effects capable of absorbing vibrations may be expected.