Multilayer ceramic electronic component and board having the same mounted thereon

A multilayer ceramic electronic component includes a multilayer ceramic capacitor including a ceramic body, and external electrodes disposed on first and second end surfaces of the ceramic body. First and second metal frames are each disposed along a respective one of two end surfaces of the multilayer ceramic capacitor, the first and second metal frames each disposed along upper and lower surfaces of the multilayer ceramic capacitor. An insulating cover encloses the multilayer ceramic capacitor and upper portions of the first and second metal frames. Lateral portions of the first and second metal frames disposed along end surfaces of the multilayer ceramic capacitor are in contact with the insulating cover, and lower portions of the first and second metal frames disposed along lower surfaces of the multilayer ceramic capacitor are spaced apart from the insulating cover by an interval.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority to Korean Patent Application No. 10-2017-0023722, filed on Feb. 22, 2017 with the Korean Intellectual Property Office, the entirety of which is incorporated herein by reference.

BACKGROUND

The present disclosure relates to a multilayer ceramic electronic component and a board having the same mounted thereon.

Multilayer ceramic capacitors (MLCCs), types of multilayer electronic component, are used in various types of electronic apparatuses due to inherent advantages thereof, such as small size, high capacitance, and ease of mounting.

Meanwhile, with the electrification of vehicles, the electronic control of such vehicles has become popular. As a result, the number of electrical control units (ECUs) mounted in such vehicles has increased. Further, operation control systems have increased in complexity due to the need for communications and networking between ECUs. Ultimately, each ECU that is directly associated with the safety performance of a vehicle requires high degrees of reliability and durability.

Such ECUs are used in environments in which temperatures are high, sudden changes in temperature can occur, and the ECUs may be exposed to mechanical stresses such as vibrations and shocks for an extended period of time.

The ECUs may each contain one or more MLCCs having excellent thermal or electrical reliability.

Such MLCCs may each include a stack of a plurality of dielectric layers, as well as internal electrodes alternately disposed between the dielectric layers and having different polarities through the stack.

Here, since the dielectric layers respectively have piezoelectric properties, when a direct current (DC) or alternating current (AC) voltage is applied to the MLCC, a piezoelectric phenomenon may occur between the internal electrodes, in which periodic vibrations are generated while the volume of a ceramic body is expanded and contracted, depending on the frequency of the voltage applied thereto.

Such vibrations may be transferred to a board through external electrodes of the MLCC and solders connecting the external electrodes to the board, such that the entirety of the board may act as a sound reflecting surface to generate vibration sound, experienced by users as noise.

The vibration sound may correspond to an audio frequency within a range of 20 Hz to 20,000 Hz, causing listener discomfort. The vibration sound causing listener discomfort, as described above, is known as acoustic noise.

Such acoustic noise may cause a reduction in quality of devices.

Meanwhile, as causes of defects in MLCCs, there may be cracking, or the like, due to the mechanical stress resulting from the vibrations described above. As a result, external moisture may permeate into the MLCC, and thus a level of insulating resistance may be reduced and the ECU may fail or otherwise stop operating.

Thus, a need exists for improving the reliability of MLCCs used in ECUs.

SUMMARY

An aspect of the present disclosure may provide a multilayer ceramic electronic component capable of reducing acoustic noise and increasing reliability of an electronic component, and a board having the same mounted thereon.

According to an aspect of the present disclosure, a multilayer ceramic electronic component includes: a multilayer ceramic capacitor including a ceramic body, and external electrodes disposed on first and second end surfaces of the ceramic body, the ceramic body having a plurality of dielectric layers and first and second internal electrodes alternately disposed between pairs of adjacent dielectric layers of the plurality of dielectric layers; first and second metal frames respectively disposed along first and second end surfaces of the multilayer ceramic capacitor, the first and second metal frames each being disposed along portions of upper and lower surfaces of the multilayer ceramic capacitor; and an insulating cover enclosing the multilayer ceramic capacitor and upper portions of the first and second metal frames. Lateral portions of the first and second metal frames disposed along end surfaces of the multilayer ceramic capacitor are in contact with the insulating cover, and lower portions of the first and second metal frames disposed along lower surfaces of the multilayer ceramic capacitor are spaced apart from the insulating cover by an interval.

According to another aspect of the present disclosure, a board assembly having a multilayer ceramic electronic component may include: a board having first and second electrode pads mounted thereon; and the multilayer ceramic electronic component mounted on the first and second electrode pads. The first and second metal frames are connected to the first and second electrode pads, respectively.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure will be described with reference to schematic views illustrating embodiments of the present disclosure. 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 disclosure should not be construed as being limited to the particular shapes of regions shown herein, for example, to include a change in shape resulting from manufacturing. The following embodiments may also be constituted alone or as a combination of several or all thereof.

The contents of the present disclosure described below may have a variety of configurations, and only a required configuration is proposed herein, but the present disclosure is not limited thereto.

FIG. 1is a perspective view schematically illustrating a multilayer ceramic electronic component according to an exemplary embodiment.

Referring toFIG. 1, the multilayer ceramic electronic component may include a multilayer ceramic capacitor, including a ceramic body110and first and second external electrodes131and132, first and second metal frames141and142, and an insulating cover161, enclosing the multilayer ceramic capacitor and upper portions of the first and second metal frames141and142.

In the exemplary embodiment, the ceramic body110may be formed by stacking a plurality of dielectric layers111(refer toFIG. 5) in a thickness direction of the ceramic body110and then sintering the dielectric layers111.

The respective adjacent dielectric layers111of the ceramic body110may be integrated with each other, so that boundaries therebetween may not be readily confirmed.

Further, the ceramic body110may have a hexahedral shape. However, the present disclosure is not limited thereto.

Directions of a hexahedron of the ceramic body110will be defined in order to more clearly describe exemplary embodiments. L, W, and T directions, depicted inFIG. 1, refer to a length direction, a width direction, and a thickness direction, respectively. A lower surface may be defined as a mounting surface, and an upper surface may be defined as opposing the mounting surface.

Further, cover layers, having a predetermined thickness, may be disposed above an upper surface of an internal electrode positioned uppermost in the ceramic body110and below a lower surface of an internal electrode positioned lowermost in the ceramic body110, respectively.

The cover layer may be formed of the same composition as the dielectric layers111, and may be formed by stacking at least one dielectric layer that does not include an internal electrode on upper and lower surfaces of the ceramic body110, respectively.

In the exemplary embodiment, the first and second metal frames141and142may have an approximately U shape.

The first and second metal frames141and142may include first and second terminal parts141band142bdisposed on a mounting surface of the ceramic body110and serving as a terminal for mounting on a board; first and second horizontal parts141cand142copposing the first and second terminal parts141band142bwith the ceramic body110disposed therebetween and connected to the first and second external electrodes131and132, respectively, on a surface of the ceramic body110opposite the mounting surface; and first and second vertical parts141aand142aconnecting the first and second horizontal parts141cand142cto the first and second terminal parts141band142b, respectively.

Further, the first and second terminal parts141band142bmay be subjected to surface treatment such as nickel (Ni)/tin (Sn) plating and/or Ni/gold (Au) plating, if desired, so that a contact feature with solders may be excellent at the time of mounting the multilayer ceramic capacitor on the board.

In the exemplary embodiment, the first and second horizontal parts141cand142cthat are the upper portions of the first and second metal frames141and142may be electrically connected to the first and second external electrodes131and132of the multilayer ceramic capacitor by first and second conductive adhesives151and152, respectively.

In an exemplary embodiment, the first and second vertical parts141aand142athat are lateral portions of the first and second metal frames141and142may be spaced apart from the first and second external electrodes131and132, respectively.

Further, the first and second terminal parts141band142bthat are lower portions of the first and second metal frames141and142may be spaced apart from the first and second external electrodes131and132, respectively.

Thus, the first and second metal frames141and142may have a structure in which only the first and second horizontal parts141cand142cthat are the upper portions of the first and second metal frames141and142may be attached to the first and second external electrodes131and132, respectively, to reduce an area for transferring the vibrations of the first and second external electrodes131and132, thus further reducing acoustic noise.

Further, the first and second metal frames141and142may absorb mechanical stress due to the deformation of the mounting board by elastic force and reduce the transfer of mechanical stress from the board to the ceramic body110, so as to prevent defects or damage such as cracking in the ceramic body110caused by mechanical stress, thus increasing reliability.

Further, according to the exemplary embodiment, even in the case that an interval between the first and second terminal parts141band142bof the first and second metal frames141and142and the first and second external electrodes131and132is set to be a significantly reduced value, sufficient elastic force may be obtained from the first and second metal frames141and142. Thus, a height of the multilayer ceramic electronic component may be reduced further than that of the existing metal frame product in which the interval between the lower terminal part and the lower surface of the multilayer ceramic capacitor is large.

Plating layers (not illustrated) may be formed on the first and second metal frames141and142.

Examples of the plating layers may include first and second Ni plating layers respectively formed on the first and second metal frames141and142, and first and second Sn plating layers respectively formed on the first and second Ni plating layers.

Other examples of the plating layers may include first and second Ni plating layers respectively formed on the first and second metal frames141and142, and first and second Au plating layers respectively formed on the first and second Ni plating layers.

FIGS. 2A through 2Care perspective views illustrating respective operations of a process of manufacturing the multilayer ceramic electronic component ofFIG. 1.

Referring toFIG. 2A, lower surfaces of the first and second metal frames141and142may have the first and second conductive adhesives151and152, respectively, applied thereto. The first and second conductive adhesives151and152may be electrically connected to upper surfaces of the external electrodes131and132, respectively, of the multilayer ceramic capacitor, including the first and second external electrodes131and132disposed on both end surfaces of the ceramic body110in the length direction.

As the first and second conductive adhesives151and152, a conductive resin paste may be used, but the present disclosure is not limited thereto. For example, soldering in a high temperature state may also be used.

Referring toFIG. 2B, the insulating cover161may be formed or disposed to enclose the multilayer ceramic capacitor and the upper portions of the upper portions of the first and second metal frames141and142. The insulating cover161may be formed using an insulating material to cover the multilayer ceramic capacitor having the first and second external electrodes131and132connected by the first and second conductive adhesives151and152to the first and second metal frames141and142.

The insulating material may be formed of a thermosetting resin such as an epoxy resin, but the present disclosure is not limited thereto.

Referring toFIG. 2C, the first and second metal frames141and142may be bent along the insulating cover161to form lateral and lower portions of the first and second metal frames141and142.

Accordingly, a cross section of each of the first and second metal frames141and142may have an approximately U shape.

FIG. 3is a cross-sectional view illustrating an interior of the multilayer ceramic electronic component ofFIG. 1.

Referring toFIG. 3, the insulating cover161may be formed or disposed to enclose the multilayer ceramic capacitor and the upper portions of the first and second metal frames141and142, while the first and second external electrodes131and132of the multilayer ceramic capacitor are connected to the first and second metal frames141and142by the first and second conductive adhesives151and152.

The insulating cover161may enclose the multilayer ceramic capacitor and the first and second horizontal parts141cand142cthat are the upper portions of the first and second metal frames141and142. The first and second terminal parts141band142band the first and second vertical parts141aand142athat are the lower and lateral portions of the first and second metal frames141and142may be exposed externally.

In an exemplary embodiment, the first and second vertical parts141aand142athat are the lateral portions of the first and second metal frames141and142may be in contact with the insulating cover161.

Further, the first and second terminal parts141band142bthat are the lower portions of the first and second metal frames141and142may be spaced apart from the insulating cover161by a predetermined interval.

According to an exemplary embodiment, the first and second vertical parts141aand142athat are the lateral portions of the first and second metal frames141and142may be in contact with the insulating cover161. In contrast, the first and second terminal parts141band142bthat are the lower portions of the first and second metal frames141and142may be spaced apart from the insulating cover161by the predetermined interval, thus reducing acoustic noise.

The first and second terminal parts141band142bare spaced apart from end surfaces of the multilayer ceramic capacitor, and the insulating cover161fills a space between the first and second terminal parts141band142band the end surfaces of the multilayer ceramic capacitor.

A structure, according to an exemplary embodiment, may have a better acoustic noise reduction effect than a common multilayer ceramic capacitor having no conventional metal frame, a structure to which only a metal frame is applied, and a structure to which a metal frame and an insulating cover are applied and in which lateral and lower portions of the metal frame are spaced apart from the insulating cover by a predetermined interval.

Further, according to an exemplary embodiment, the multilayer ceramic capacitor may be wrapped with an insulating resin to form the insulating cover161to prevent external moisture from permeating into the multilayer ceramic capacitor, thus increasing moisture resistance properties of the multilayer ceramic capacitor.

According to an exemplary embodiment, the first and second metal frames141and142may be formed of a material having a Young's modulus within a range of 50 GPa to 200 GPa.

Thus, mechanical strength may be excellent while reducing acoustic noise.

When the first and second metal frames141and142have a Young's modulus of 50 GPa or less, an acoustic noise reduction effect may be excellent due to good vibration absorption capabilities, but mechanical strength may be low.

When the first and second metal frames141and142have a Young's modulus greater than 200 GPa, the acoustic noise reduction effect may be low due to reduced vibration absorption capabilities.

FIG. 4is a cross-sectional view illustrating an interior of a multilayer ceramic electronic component according to another exemplary embodiment.

Referring toFIG. 4, the multilayer ceramic electronic component, according to another exemplary embodiment, may have additional first and second solder paste layers153and154respectively interposed between end portions of the insulating cover161and the conductive adhesives151and152.

The first and second solder paste layers153and154may be further inserted to further increase the sealability of the multilayer ceramic electronic component according to another exemplary embodiment, thus achieving better moisture resistance properties.

FIG. 5is an exploded perspective view schematically illustrating an example of an internal electrode disposition structure of a multilayer ceramic electronic component according to an exemplary embodiment.

A thickness of one dielectric layer111may be arbitrarily changed depending on a capacitance design of the multilayer ceramic capacitor. Further, the dielectric layer111may contain a high-k ceramic material, for example, a BaTiO3-based ceramic powder, or the like. However, the present disclosure is not limited thereto.

Examples of the BaTiO3-based ceramic powder may include (Ba1-xCax)TiO3, Ba(Ti1-yCay)O3, (Ba1-xCax)(Ti1-yZry)O3, and Ba(Ti1-yZry)O3in which calcium (Ca), zirconium (Zr), or the like is partially dissolved in BaTiO3, but the present disclosure is not limited thereto.

The dielectric layer111may further contain a ceramic additive, an organic solvent, a plasticizer, a binder, a dispersant, or the like, in addition to the ceramic powder.

As the ceramic additive, for example, at least one of a transition metal oxide, a carbide, a rare earth element, magnesium (Mg), aluminum (Al), or the like may be used.

As illustrated inFIG. 5, first and second internal electrodes121and122may alternately be formed on adjacent ceramic sheets, forming the dielectric layers111, may be stacked in the thickness direction, and may then be sintered, such that the first and second internal electrodes121and122may alternately be disposed in the ceramic body110with each of the dielectric layers111interposed therebetween.

The first and second internal electrodes121and122, having different polarities, may oppose each other in a direction in which the dielectric layers111are stacked, and may be electrically insulated from each other by the dielectric layers111disposed therebetween.

One end portion of each first internal electrode121may be exposed through one end surface of the ceramic body110, and one end portion of each second internal electrode122may be exposed through the other end surface of the ceramic body110opposite to the one end surface in the length direction of the ceramic body110.

The end portions of the first and second internal electrodes121and122alternately exposed through both end surfaces of the ceramic body110in the length direction, as described above, may respectively be electrically connected to the first and second external electrodes131and132disposed on both end surfaces of the ceramic body110in the length direction.

Hereinafter, the first and second external electrodes131and132may be separately termed the first external electrode131and the second external electrode132.

Here, the first and second internal electrodes121and122may be formed of a conductive metal, for example, a material such as Ni, a Ni alloy, or the like. However, the present disclosure is not limited thereto.

According to the configuration as described above, when predetermined levels of voltages are applied to the first and second external electrodes131and132, electric charges may be accumulated on the first and second internal electrodes121and122opposing each other.

Here, a capacitance of the multilayer ceramic capacitor may be proportional to an area of a region in which the first and second internal electrodes121and122are overlapped with each other in the direction in which the dielectric layers111are stacked.

Meanwhile, the exemplary embodiment illustrates a horizontal stack type multilayer ceramic capacitor in which the first and second internal electrodes121and122are stacked in the thickness direction of the ceramic body110that is parallel to the mounting surface, but the present disclosure is not limited thereto.

The first and second external electrodes131and132may be formed by sintering conductive pastes for forming external electrodes containing copper (Cu), in order to have good electrical properties and provide high reliability such as excellent heat cycle resistance, moisture resistance, and the like. However, the present disclosure is not limited thereto.

Plating layers (not illustrated) may be formed on the first and second external electrodes131and132.

Examples of the plating layers may include first and second Ni plating layers respectively formed on the first and second metal frames131and132, and first and second Sn plating layers respectively formed on the first and second Ni plating layers.

Table 1 below illustrates the results of comparison between an acoustic noise value according to an example and acoustic noise values according to Comparative Examples 1 to 3.

An example of an exemplary embodiment illustrates a structure which includes a multilayer ceramic capacitor, first and second metal frames, and an insulating cover, and in which lateral portions of the first and second metal frames are in contact with the insulating cover, and lower portions of the first and second metal frames are spaced apart from the insulating cover by a predetermined interval.

Comparative Example 1 is a structure as a conventional multilayer ceramic capacitor, having no metal frame and insulating cover.

Comparative Example 2 is a structure in which only a metal frame is disposed on a multilayer ceramic capacitor.

Comparative Example 3 is a structure in which a metal frame and an insulating cover are disposed on a multilayer ceramic capacitor, and lateral and lower portions of the metal frame are spaced apart from the insulating cover by a predetermined interval.

The multilayer ceramic capacitor, used in the tests, a product having a 3225 size (length×width×thickness, 3.2 mm×2.5 mm×2.5 mm) and a capacitance of 220 μF that was subjected to the test.

Referring to Table 1 above, it can be seen that the example in which the lateral portions of the first and second metal frames are in contact with the insulating cover and the lower portions thereof are spaced apart from the insulating cover by the predetermined interval has an acoustic noise reduction effect better than those of Comparative Examples 1 to 3.

FIG. 6is a cross-sectional view illustrating a board assembly200having a multilayer ceramic electronic component according to an exemplary embodiment.

Referring toFIG. 6, the board assembly200, having the multilayer ceramic electronic component according to the exemplary embodiment, may include a board210on which the multilayer ceramic electronic component is mounted, and first and second electrode pads211and212formed on an upper surface of the board210to be spaced apart from each other in the length direction.

While first and second terminal parts141band142bof first and second metal frames141and142disposed on a lower surface of a ceramic body110are respectively connected to the first and second electrode pads211and212on the board210, multilayer ceramic electronic components may be bonded by first and second solders221and222to be electrically connected to each other.

As described above, when voltages having different polarities are applied to first and second external electrodes131and132of the multilayer ceramic capacitor through the first and second metal frames141and142with the multilayer electronic component mounted on the board210, an inverse piezoelectric effect of the dielectric layer may cause the ceramic body110to expand and contract in the thickness direction, and both end portions of the first and second external electrodes131and132may contract and expand as opposed to the expansion and the contraction of the ceramic body110in the thickness direction due to the Poisson effect.

The above-mentioned expansion and contraction of the ceramic body110may generate vibrations which may be transferred to the board210through the first and second external electrodes131and132to radiate sound from the board210, experienced as acoustic noise.

According to the exemplary embodiment, the piezoelectric vibrations, transferred to the board210through the first and second external electrodes131and132of the multilayer ceramic capacitor, may be absorbed or attenuated by the elasticity of the first and second metal frames141and142, and mechanical stress, generated due to warpage of the board210, or the like, may also be absorbed by the first and second metal frames141and142, thus reducing the acoustic noise of the product.

In particular, first and second vertical parts141aand142athat are lateral portions of the first and second metal frames141and142may be in contact with an insulating cover161. In contrast, the first and second terminal parts141band142bthat are lower portions of the first and second metal frames141and142may be spaced apart from the insulating cover161by a predetermined interval, thus achieving a better acoustic noise reduction effect.

Further, because the first and second metal frames141and142absorb the mechanical stress, the stress may not be transferred to the multilayer ceramic capacitor, thus preventing damage such as cracking.

Further, the multilayer ceramic capacitor may be covered with an insulating resin, thus increasing moisture resistance properties.

As set forth above, according to the exemplary embodiments, since a metal frame may absorb mechanical stress, the stress may not be transferred to a multilayer ceramic capacitor (MLCC), thus preventing damage such as cracking.

Further, the MLCC may be covered with an insulating resin, thus increasing moisture resistance properties.

Further, the elasticity of the metal frame may absorb vibrations transferred through an external electrode of a ceramic body, thus reducing acoustic noise.