CN110797191A - Multilayer ceramic capacitor and method of manufacturing the same - Google Patents

Abstract

The present disclosure provides a multilayer ceramic capacitor and a method of manufacturing the same, the multilayer ceramic capacitor including: a ceramic body including a dielectric layer and having first and second surfaces opposite to each other, third and fourth surfaces connecting the first and second surfaces to each other, and fifth and sixth surfaces connected to the first to fourth surfaces and opposite to each other; a plurality of internal electrodes disposed in the ceramic body, exposed to the first surface and the second surface, and having one end exposed to the third surface or the fourth surface; and first and second side edge portions provided on the first and second surfaces of the ceramic main body, respectively, exposing the internal electrodes. The thickness of each of the first side edge portion and the second side edge portion is 10 μm or more and less than 45 μm.

Description

Multilayer ceramic capacitor and method of manufacturing the same

This application claims the benefit of priority of korean patent application No. 10-2018-0102123 filed in the korean intellectual property office at 29.8.2018 and korean patent application No. 10-2018-0090717 filed in the korean intellectual property office at 3.8.2018, the disclosures of which are incorporated herein by reference in their entireties.

Technical Field

The present disclosure relates to a multilayer ceramic capacitor and a method of manufacturing the same, which can have improved moisture-proof reliability by controlling the thickness of side edge portions provided on side surfaces of a ceramic main body to prevent penetration of moisture.

Background

In general, an electronic component (such as a capacitor, an inductor, a piezoelectric element, a varistor, a thermistor, etc.) using a ceramic material includes a ceramic body formed using a ceramic material, internal electrodes formed in the ceramic body, and external electrodes disposed on a surface of the ceramic body to be connected to the internal electrodes.

Recently, as electronic products are miniaturized and multi-functionalized, multilayer ceramic electronic components are also tending to be miniaturized and multi-functionalized. Therefore, there has been a demand for a multilayer ceramic capacitor having a small size and a high capacitance.

In order to miniaturize and increase the capacitance of the multilayer ceramic capacitor, it is necessary to significantly increase the electrode effective area (increase the effective volume fraction required to achieve the capacitance).

In order to realize the miniaturized and high-capacitance multilayer ceramic capacitor as described above, in manufacturing the multilayer ceramic capacitor, a method of significantly increasing the area of the inner electrode in the width direction of the body by a rimless design has been used as follows: the multilayer ceramic capacitor is completed by exposing the internal electrodes in the width direction of the body, and by separately attaching the side edge portions to the electrode exposed surfaces in the width direction of the multilayer ceramic capacitor body in a process before sintering after manufacturing the multilayer ceramic capacitor body.

However, in this method, when the thickness of the side edge portion is excessively small in the process of forming the side edge portion, moisture may penetrate into the main body, so that moisture-proof reliability may be lowered.

Therefore, there has been a need for research into a technology capable of improving moisture-proof reliability of a subminiature and high-capacitance multilayer ceramic capacitor.

Disclosure of Invention

An aspect of the present disclosure may provide a multilayer ceramic capacitor having improved moisture-proof reliability by preventing penetration of moisture by controlling a thickness of a side edge portion disposed on a side surface of a ceramic main body, and a method of manufacturing the same.

According to an aspect of the present disclosure, a multilayer ceramic capacitor may include: a ceramic body including a dielectric layer and having first and second surfaces opposite to each other, third and fourth surfaces connecting the first and second surfaces to each other, and fifth and sixth surfaces connected to the first to fourth surfaces and opposite to each other; a plurality of internal electrodes disposed in the ceramic body, exposed to the first surface and the second surface, and having one end exposed to the third surface or the fourth surface; and first and second side edge portions provided on the first and second surfaces of the ceramic main body, respectively, exposing the internal electrodes. Each of the first side edge portion and the second side edge portion may have a thickness of 10 μm or more and less than 45 μm.

According to another aspect of the present disclosure, a method of manufacturing a multilayer ceramic capacitor may include: preparing first ceramic green sheets having a plurality of first internal electrode patterns formed thereon at predetermined intervals and second ceramic green sheets having a plurality of second internal electrode patterns formed thereon at predetermined intervals; forming a ceramic green sheet multilayer body by stacking the first ceramic green sheet and the second ceramic green sheet such that the first internal electrode pattern and the second internal electrode pattern are overlapped with each other; cutting the multilayer body of ceramic green sheets to have side surfaces exposing ends of the first and second internal electrode patterns in a width direction; forming first and second side edge portions on side surfaces exposing the ends of the first and second internal electrode patterns, respectively; a ceramic body including dielectric layers and internal electrodes is prepared by sintering the cut multilayer body of ceramic green sheets. Each of the first side edge portion and the second side edge portion may have a thickness of 10 μm or more and less than 45 μm.

Drawings

The above and other aspects, features and advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

fig. 1 is a schematic perspective view illustrating a multilayer ceramic capacitor according to an exemplary embodiment in the present disclosure;

fig. 2 is a perspective view showing an exterior of the ceramic main body of fig. 1;

FIG. 3 is a perspective view showing a multilayer body of ceramic green sheets before sintering the ceramic main body of FIG. 2;

fig. 4 is a side view when viewed in the direction B of fig. 2;

fig. 5A to 5F are a schematic cross-sectional view and a schematic perspective view illustrating a method of manufacturing a multilayer ceramic capacitor according to another exemplary embodiment in the present disclosure.

Detailed Description

Hereinafter, exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings.

Fig. 1 is a schematic perspective view illustrating a multilayer ceramic capacitor according to an exemplary embodiment in the present disclosure.

Fig. 2 is a perspective view showing an exterior of the ceramic main body of fig. 1.

Fig. 3 is a perspective view showing a multilayer body of ceramic green sheets before sintering the ceramic main body of fig. 2.

Fig. 4 is a side view when viewed in the B direction of fig. 2.

Referring to fig. 1 to 4, the multilayer ceramic capacitor 100 according to the present exemplary embodiment may include a ceramic body 110, a plurality of internal electrodes 121 and 122 formed in the ceramic body 110, and external electrodes 131 and 132 formed on an outer surface of the ceramic body 110.

The ceramic body 110 may have first and second surfaces 1 and 2 opposite to each other, third and fourth surfaces 3 and 4 connecting the first and second surfaces to each other, and fifth and sixth surfaces 5 and 6 as upper and lower surfaces, respectively.

The first surface 1 and the second surface 2 refer to surfaces of the ceramic main body 110 that are opposite to each other in the width direction W (second direction), the third surface 3 and the fourth surface 4 refer to surfaces of the ceramic main body 110 that are opposite to each other in the length direction L (first direction), and the fifth surface 5 and the sixth surface 6 refer to surfaces of the ceramic main body 110 that are opposite to each other in the thickness direction T (third direction).

The shape of the ceramic main body 110 is not particularly limited, but may be a rectangular parallelepiped shape as shown.

One ends of the plurality of internal electrodes 121 and 122 formed in the ceramic main body 110 may be exposed to the third surface 3 or the fourth surface 4 of the ceramic main body.

The internal electrodes 121 and 122 may include a pair of first and second internal electrodes 121 and 122 having different polarities.

One end of the first internal electrode 121 may be exposed to the third surface 3 and one end of the second internal electrode 122 may be exposed to the fourth surface 4.

The other end of the first internal electrode 121 may be spaced apart from the fourth surface 4 by a predetermined interval. The other end of the second internal electrode 122 may be spaced apart from the third surface 3 by a predetermined interval.

The first and second external electrodes 131 and 132 may be formed on the third and fourth surfaces 3 and 4 of the ceramic main body, respectively, and may be electrically connected to the internal electrodes.

The multilayer ceramic capacitor 100 according to an exemplary embodiment in the present disclosure may include a plurality of internal electrodes 121 and 122 disposed in the ceramic main body 110, exposed to the first surface 1 and the second surface 2, and having one ends exposed to the third surface 3 or the fourth surface 4, and first and second side edge portions 112 and 113 disposed on side portions (i.e., distal ends) of the internal electrodes 121 and 122 exposed to the first and second surfaces 1 and 2, respectively.

A plurality of internal electrodes 121 and 122 may be formed in the ceramic main body 110, respective side portions of the plurality of internal electrodes 121 and 122 may be exposed to the first and second surfaces 1 and 2 (surfaces of the ceramic main body 110 in the width direction), and first and second side edge portions 112 and 113 may be disposed on the exposed side portions.

The average thickness tc of each of the first and second side edge portions 112, 113 may be 10 μm or more and less than 45 μm.

According to an exemplary embodiment in the present disclosure, the ceramic main body 110 may include a laminate in which a plurality of dielectric layers 111 are stacked, and a first side edge portion 112 and a second side edge portion 113 respectively disposed on opposite side surfaces of the laminate.

The plurality of dielectric layers 111 may be in a sintered state, and adjacent dielectric layers may be integrated with each other such that the boundary therebetween is not easily apparent.

The length of the ceramic body 110 may correspond to the distance from the third surface 3 of the ceramic body to the fourth surface 4 of the ceramic body.

The length of the dielectric layer 111 may form the distance between the third surface 3 and the fourth surface 4 of the ceramic body.

According to an exemplary embodiment in the present disclosure, the length of the ceramic body may be 400 to 1400 μm, but is not limited thereto. More specifically, the length of the ceramic body may be 400 μm to 800 μm or may be 600 μm to 1400 μm.

The internal electrodes 121 and 122 may be formed on the dielectric layer 111, and the internal electrodes 121 and 122 may be formed in the ceramic main body by sintering with the dielectric layer interposed between the internal electrodes 121 and 122.

Referring to fig. 3, the first internal electrode 121 may be formed on the dielectric layer 111. The first internal electrode 121 may not be completely formed on the dielectric layer in the length direction of the dielectric layer. That is, one end of the first internal electrode 121 may be formed up to the third surface 3 to be exposed to the third surface 3, and the other end of the first internal electrode 121 may be formed to be separated from the fourth surface of the ceramic main body by a predetermined interval.

An end portion of the first internal electrode exposed to the third surface 3 of the ceramic body may be connected to the first external electrode 131.

Opposite to the first internal electrode, one end of the second internal electrode 122 may be exposed to the fourth surface 4 to be connected to the second external electrode 132, and the other end of the second internal electrode 122 may be formed to be separated from the third surface 3 by a predetermined interval.

In order to realize a high-capacitance multilayer ceramic capacitor, four hundred or more layers of internal electrodes may be stacked, but the number of internal electrodes is not necessarily limited thereto.

The dielectric layer 111 may have the same width as that of the first inner electrode 121. That is, the first internal electrodes 121 may be entirely formed on the dielectric layer 111 in the width direction thereof. The dielectric layer 111 may have the same width as that of the second inner electrode 122. That is, the second internal electrodes 122 may be entirely formed on the dielectric layer 111 in the width direction thereof.

According to an exemplary embodiment in the present disclosure, the width of the dielectric layer and the width of the internal electrode may be 100 to 900 μm, but is not limited thereto. More specifically, the width of the dielectric layer and the width of the internal electrode may be 100 μm to 500 μm or may be 100 μm to 900 μm.

Since the ceramic main body is miniaturized, the thickness of each of the side edge portions has an influence on the electrical characteristics of the multilayer ceramic capacitor. According to an exemplary embodiment in the present disclosure, each of the side edge portions may be formed in a thickness of less than 45 μm, so that moisture-proof characteristics and other electrical characteristics of the miniaturized multilayer ceramic capacitor may be improved.

That is, each of the side edge portions may be formed with a thickness of less than 45 μm, so that a stacking area forming capacitance between the internal electrodes may be secured as much as possible to realize a high capacitance and a small-sized multilayer ceramic capacitor. Further, each of the side edge portions may be formed with a thickness of less than 45 μm, so that moisture may be prevented from penetrating into the ceramic main body to improve moisture-proof reliability of the multilayer ceramic capacitor.

The ceramic body 110 may include an effective portion a contributing to the capacitance forming the capacitor, and upper and lower cover portions 114 and 115 as upper and lower edge portions formed on upper and lower surfaces of the effective portion a, respectively.

The effective portion a may be formed by repeatedly stacking a plurality of first and second internal electrodes 121 and 122 with the dielectric layer 111 interposed between the first and second internal electrodes 121 and 122.

The upper and lower caps 114 and 115 may be formed using the same material as that of the dielectric layer 111 and have the same configuration as that of the dielectric layer 111, except that the upper and lower caps 114 and 115 do not include an inner electrode.

That is, the upper and lower caps 114 and 115 may include a ceramic material, such as barium titanate (BaTiO)₃) A base ceramic material.

Each of the upper and lower sheathing parts 114 and 115 may have a thickness of 20 μm or less, but is not necessarily limited thereto.

In exemplary embodiments in the present disclosure, the internal electrodes and the dielectric layers, which are simultaneously cut and formed, may be formed with the same width. More details thereof will be described below.

In the present exemplary embodiment, the dielectric layer may be formed in the same width as that of the internal electrodes, and thus side portions of the internal electrodes 121 and 122 may be exposed to the first and second surfaces of the ceramic main body 110 in the width direction.

The first and second side edge portions 112 and 113 may be formed on the opposite side surfaces of the ceramic main body 110 in the width direction, to which the side portions of the internal electrodes 121 and 122 are exposed, respectively.

Each of the first side edge portion 112 and the second side edge portion 113 may have a thickness of less than 45 μm. In the case of a multilayer ceramic capacitor having the same size, the smaller the thickness of each of the first side edge portion 112 and the second side edge portion 113, the larger the overlapping area between the internal electrodes formed in the ceramic main body.

The thickness of each of the first side edge portion 112 and the second side edge portion 113 is not particularly limited as long as a short circuit between internal electrodes exposed to the side surface of the ceramic main body due to moisture penetration can be prevented, and may be, for example, 10 μm or more.

When the thickness of each of the first and second side edge portions 112 and 113 is 10 μm or more, the moisture permeability may be substantially 0.

When the thickness of each of the first and second side edge portions 112 and 113 is less than 10 μm, the thickness of each of the first and second side edge portions 112 and 113 may be small, so that moisture may penetrate into the ceramic main body through the side edge portions, thereby degrading moisture-proof reliability.

Meanwhile, when the thickness of each of the first and second side edge portions 112 and 113 is 45 μm or more, the overlapping area between the internal electrodes may be relatively reduced, so that it may be difficult to secure a high capacitance of the multilayer ceramic capacitor.

Further, in the case where the thickness of each of the first side edge portion 112 and the second side edge portion 113 is 45 μm or more, sintering may not be sufficiently performed at the same sintering temperature, so that holes may be generated in the surface of each of the first side edge portion 112 and the second side edge portion 113, thereby increasing surface moisture absorption, as compared to the case where the thickness of each of the first side edge portion 112 and the second side edge portion 113 is less than 45 μm. Therefore, the reliability of moisture resistance may be lowered.

In order to significantly improve the capacitance of the multilayer ceramic capacitor, a method of reducing the thickness of each of the dielectric layers, a method of increasing the number of dielectric layers stacked in which the thickness of each of the dielectric layers is reduced, a method of improving the coverage of each of the internal electrodes, and the like have been considered.

Further, a method of increasing the overlap area between the internal electrodes forming the capacitance has been considered.

In order to increase the overlapping area between the internal electrodes, it is necessary to significantly reduce the area of the edge portion in which the internal electrodes are not formed.

In particular, as the multilayer ceramic capacitor is miniaturized, the edge portion region needs to be significantly reduced to increase the overlapping area between the internal electrodes.

Generally, as the number of stacked dielectric layers increases, the thicknesses of the dielectric layers and the internal electrodes may decrease. Therefore, a phenomenon of short-circuiting of the internal electrodes frequently occurs. In addition, when the internal electrodes are formed only on a portion of the dielectric layer, steps due to the internal electrodes may be generated, so that the insulation resistance or reliability of the multilayer ceramic capacitor may be lowered.

However, according to the present exemplary embodiment, even if the internal electrodes and the dielectric layers formed using the thin films are formed, since the internal electrodes may be completely formed on the dielectric layers in the width direction of the dielectric layers, the overlapping area between the internal electrodes may be increased, and thus the capacitance of the multilayer ceramic capacitor may be increased.

Further, steps due to the internal electrodes can be reduced, so that insulation resistance can be improved, and a multilayer ceramic capacitor having excellent capacitance characteristics and excellent reliability can be provided.

According to the present exemplary embodiment, the internal electrodes may be formed on the entire dielectric layer in the width direction of the dielectric layer, and each of the side edge portions may be set to 10 μm or more and less than 45 μm, so that the overlapping area between the internal electrodes may be large.

Therefore, a subminiature and high-capacitance multilayer ceramic capacitor can be realized, and moisture-proof reliability can also be improved.

In particular, the multilayer ceramic capacitor according to an exemplary embodiment in the present disclosure may be a subminiature and high-capacitance multilayer ceramic capacitor in which the thickness of the dielectric layer 111 is 0.4 μm or less and the thickness of each of the internal electrodes 121 and 122 is 0.4 μm or less.

As in the exemplary embodiment in the present disclosure, in the case of a subminiature and high-capacitance multilayer ceramic capacitor in which the dielectric layer 111 and the internal electrodes 121 and 122 formed using a thin film having a thickness of 0.4 μm or less are used, a problem of a decrease in moisture-proof reliability due to moisture penetration into the side edge portions may be a very important problem.

That is, the technology according to the exemplary embodiment in the present disclosure is applied to a subminiature and high-capacitance multilayer ceramic capacitor in which the thickness of the dielectric layer 111 is 0.4 μm or less and the thickness of each of the internal electrodes 121 and 122 is 0.4 μm or less, as compared to the multilayer ceramic capacitor according to the related art. Therefore, the thickness of the dielectric layer and the internal electrode may be small, so that the possibility that the reliability of moisture resistance will be reduced due to the penetration of moisture is increased.

However, as in the exemplary embodiment in the present disclosure, in the subminiature and high-capacitance multilayer ceramic capacitor to which the separate side edge portions are attached, the average thickness tc of each of the first and second side edge portions 112 and 113 may be controlled to be 10 μm or more and less than 45 μm, so that the moisture-proof reliability may be improved even in the case where the dielectric layer 111 and the first and second internal electrodes 121 and 122 are formed using a thin film having a thickness of 0.4 μm or less.

However, the thin film does not mean that the thickness of the dielectric layer 111 and the first and second internal electrodes 121 and 122 is 0.4 μm or less, but may conceptually include: the thicknesses of the dielectric layers and the internal electrodes are less than those of the dielectric layers and the internal electrodes of the multilayer ceramic capacitor according to the related art.

Referring to fig. 4, a ratio of a thickness tc2 of a region of the first or second side edge portion contacting a tip of an internal electrode disposed at an outermost portion of the ceramic main body in a direction in which the plurality of internal electrodes are stacked to a thickness tc1 of a region of the first or second side edge portion contacting a tip of an internal electrode disposed in a central portion of the ceramic main body in a direction in which the plurality of internal electrodes are stacked may be 1.0 or less.

A lower limit value of a ratio of a thickness tc2 of a region of the first or second side edge portion that is in contact with a tip of an internal electrode disposed at an outermost portion of the ceramic main body in a direction in which the plurality of internal electrodes are stacked to a thickness tc1 of a region of the first or second side edge portion that is in contact with a tip of an internal electrode disposed at a central portion of the ceramic main body in the direction in which the plurality of internal electrodes are stacked is not particularly limited, and may be 0.9 or more.

According to exemplary embodiments in the present disclosure, unlike the related art, the first or second side edge portion may be formed by attaching a ceramic green sheet to a side surface of a ceramic main body, and thus, the thickness of the first or second side edge portion at each position may be constant.

That is, in the related art, the side edge portion is formed in such a manner that the ceramic paste is applied or printed, and thus the deviation of the thickness of the side edge portion at each position is large.

In detail, in the related art, the thickness of a region of the first side edge portion or the second side edge portion, which is in contact with the tip of the internal electrode provided at the central portion of the ceramic main body, is greater than the thickness of the other region.

For example, in the related art, a ratio of a thickness of a region of the first side edge portion or the second side edge portion that is in contact with the tip of the internal electrode disposed at the outermost portion of the ceramic main body in the direction in which the plurality of internal electrodes are stacked to a thickness of a region of the first side edge portion or the second side edge portion that is in contact with the tip of the internal electrode disposed at the central portion of the ceramic main body in the direction in which the plurality of internal electrodes are stacked is less than about 0.9, so that a deviation of the thicknesses is large.

In the related art in which the deviation of the thickness of the side edge portion at each position is large, in the multilayer ceramic capacitor having the same size, the portion occupied by the side edge portion is large, so that a large-sized capacitance forming portion may not be ensured, resulting in difficulty in ensuring high capacitance.

On the other hand, in the exemplary embodiment in the present disclosure, the average thickness tc of each of the first side edge portion 112 and the second side edge portion 113 may be 10 μm or more and less than 45 μm, and the ratio of the thickness tc2 of the region of the first side edge portion or the second side edge portion that is in contact with the tip end of the internal electrode disposed at the outermost portion of the ceramic main body in the direction in which the plurality of internal electrodes are stacked to the thickness tc1 of the region of the first side edge portion or the second side edge portion that is in contact with the tip end of the internal electrode disposed at the central portion of the ceramic main body in the direction in which the plurality of internal electrodes are stacked may be 0.9 or more and 1.0 or less. Therefore, the thickness of the side edge portion can be small and the deviation of the thickness of the side edge portion can be small, so that a large-sized capacitance forming portion can be secured.

In the exemplary embodiments in the present disclosure, unlike the related art, the first side edge portion or the second side edge portion may be formed by attaching the ceramic green sheet to the side surface of the ceramic main body, and thus, the thickness of the first side edge portion or the second side edge portion at each position may be constant.

Thus, a high-capacitance multilayer ceramic capacitor can be realized.

Meanwhile, referring to fig. 4, a ratio of a thickness tc3 of a region of the first or second side edge portion contacting an edge of the ceramic main body 110 to a thickness tc1 of a region of the first or second side edge portion contacting a tip of an internal electrode among the plurality of internal electrodes 121 and 122 disposed at a central portion of the ceramic main body in a direction in which the plurality of internal electrodes are stacked may be 1.0 or less.

A lower limit value of a ratio of a thickness tc3 of a region of the first or second side edge portion in contact with an edge of the ceramic main body 110 to a thickness tc1 of a region of the first or second side edge portion in contact with a tip of an internal electrode disposed at a central portion of the ceramic main body in a direction in which the plurality of internal electrodes are stacked may be 0.9 or more.

Due to the above feature, the deviation of the thickness of the side edge portion in each region can be small, so that a large-sized capacitance forming portion can be ensured. Thus, a high-capacitance multilayer ceramic capacitor can be realized.

Fig. 5A to 5F are a schematic cross-sectional view and a schematic perspective view illustrating a method of manufacturing a multilayer ceramic capacitor according to another exemplary embodiment in the present disclosure.

According to another exemplary embodiment in the present disclosure, a method of manufacturing a multilayer ceramic capacitor may include: preparing a first ceramic green sheet on which a plurality of first internal electrode patterns are formed at predetermined intervals and a second ceramic green sheet on which a plurality of second internal electrode patterns are formed at predetermined intervals; forming a ceramic green sheet multilayer body by stacking a first ceramic green sheet and a second ceramic green sheet such that a first internal electrode pattern and a second internal electrode pattern are superposed on each other; cutting the multilayer body of ceramic green sheets to have a side surface exposing ends of the first and second internal electrode patterns in a width direction; forming first and second side edge portions on side surfaces exposing ends of the first and second internal electrode patterns, respectively; a ceramic body including dielectric layers and first and second internal electrodes is prepared by sintering the cut multilayer body of ceramic green sheets. The average thickness tc of each of the first side edge portion 112 and the second side edge portion 113 is 10 μm or more and less than 45 μm.

Hereinafter, a method of manufacturing a multilayer ceramic capacitor according to another exemplary embodiment in the present disclosure will be described.

As shown in fig. 5A, a plurality of first inner electrode patterns 221 having a bar shape may be formed on the ceramic green sheet 211 at predetermined intervals. A plurality of first inner electrode patterns 221 having a bar shape may be formed parallel to each other.

The ceramic green sheet 211 may be formed using a ceramic paste containing ceramic powder, an organic solvent, and an organic binder (binder).

As the material having a high dielectric constant, the ceramic powder may be barium titanate (BaTiO)₃) Base material, lead composite perovskite base material, strontium titanate (SrTiO)₃) A base material, etc., and may preferably be barium titanate (BaTiO)₃) Powder, but not limited thereto. When the ceramic green sheet 211 is sintered, the ceramic green sheet 211 may become the dielectric layer 111 constituting the ceramic main body 110.

The first inner electrode patterns 221 having a stripe shape may be formed using an inner electrode paste including a conductive metal. The conductive metal may be nickel (Ni), copper (Cu), palladium (Pd), or an alloy thereof, but is not limited thereto.

A method of forming the first inner electrode patterns 221 having a stripe shape on the ceramic green sheets 211 is not particularly limited, but may be a printing method such as a screen printing method or a gravure printing method.

Further, although not shown, a plurality of second internal electrode patterns 222 having a bar shape may be formed on another ceramic green sheet 211 with a predetermined interval between the plurality of second internal electrode patterns 222.

Hereinafter, the ceramic green sheet on which the first internal electrode pattern 221 is formed may be referred to as a first ceramic green sheet, and the ceramic green sheet on which the second internal electrode pattern 222 is formed may be referred to as a second ceramic green sheet.

Next, as shown in fig. 5B, the first and second ceramic green sheets may be alternately stacked such that the first internal electrode patterns 221 having a bar shape and the second internal electrode patterns 222 having a bar shape are alternately stacked.

Thereafter, the first internal electrode patterns 221 having the bar shapes may become the first internal electrodes 121, and the second internal electrode patterns 222 having the bar shapes may become the second internal electrodes 122.

According to another exemplary embodiment in the present disclosure, the thickness td of each of the first and second ceramic green sheets may be 0.6 μm or less, and the thickness te of each of the first and second internal electrode patterns may be 0.5 μm or less.

Since the subminiature and high-capacitance multilayer ceramic capacitor in which the dielectric layers and the internal electrodes are formed with the thin film having the thickness of 0.4 μm or less is provided in the present disclosure, the thickness td of each of the first and second ceramic green sheets may be 0.6 μm or less, and the thickness te of each of the first and second internal electrode patterns may be 0.5 μm or less.

Fig. 5C is a sectional view illustrating a ceramic green sheet multilayer body 220 in which a first ceramic green sheet and a second ceramic green sheet are stacked according to another exemplary embodiment in the present disclosure, and fig. 5D is a perspective view illustrating the ceramic green sheet multilayer body 220 in which the first ceramic green sheet and the second ceramic green sheet are stacked.

Referring to fig. 5C and 5D, a first ceramic green sheet on which a plurality of first internal electrode patterns 221 are printed in parallel with each other and have a bar shape and a second ceramic green sheet on which a plurality of second internal electrode patterns 222 are printed in parallel with each other and have a bar shape may be alternately stacked.

In more detail, the first and second ceramic green sheets may be stacked such that intervals between a central portion of the first internal electrode pattern 221 having a bar shape printed on the first ceramic green sheet and the second internal electrode pattern 222 having a bar shape printed on the second ceramic green sheet overlap each other.

Next, as shown in fig. 5D, the ceramic green sheet multilayer body 220 may be cut across the plurality of first inner electrode patterns 221 having a stripe shape and the plurality of second inner electrode patterns 222 having a stripe shape. That is, the ceramic green sheet multilayer body 220 may be cut into the multilayer body 210 along cutting lines C1-C1 and C2-C2 that are orthogonal to each other.

In more detail, the first and second internal electrode patterns 221 and 222 having a bar shape may be cut along a length direction (a direction of a cutting line C1-C1) to be divided into a plurality of internal electrodes having a predetermined width. In this case, the stacked ceramic green sheets may be cut together with the internal electrode patterns. Accordingly, the dielectric layer may be formed to have the same width as that of the internal electrode.

Further, the ceramic green sheet multilayer body may be cut in a single ceramic body size along the cutting line C2-C2. That is, before the first and second side edge portions are formed, a laminated body having a rod shape may be cut in a single ceramic body size along the cutting line C2-C2 to form a plurality of multilayer bodies 210.

That is, the stacked body having a bar shape may be cut such that the central portion of the first internal electrodes and the predetermined interval formed between the second internal electrodes, which are stacked one on another, are cut at the same cutting line. Accordingly, one ends of the first and second internal electrodes may be alternately exposed to the cutting surface.

Then, first and second side edge portions may be formed on the first and second side surfaces of the multi-layer body 210.

Then, as shown in fig. 5E, a first side edge portion 212 and a second side edge portion (not shown) may be formed on the first side surface and the second side surface of the multilayer body 210, respectively.

In detail, in a method of forming the first side edge portion 212, a ceramic green sheet 212 for a side surface coated with an adhesive (not shown) may be disposed on the stamp elastic material 300 formed of rubber.

Then, the multilayer body 210 may be rotated by 90 ° so that the first side surface of the multilayer body 210 faces the ceramic green sheet for side surface 212 to which a binder (not shown) is applied, and then the multilayer body 210 may be pressurized and the multilayer body 210 may be closely adhered to the ceramic green sheet for side surface 212 to which a binder (not shown) is applied.

When the ceramic green sheets 212 for the side surfaces are transferred to the multilayer body 210 by pressurizing the multilayer body 210 and closely adhering the multilayer body 210 to the ceramic green sheets 212 for the side surfaces to which a binder (not shown) is applied, the ceramic green sheets 212 for the side surfaces may be formed to edge portions of the side surfaces of the multilayer body 210 due to the punching elastic material 300 formed using rubber, and the remaining portions may be cut.

Fig. 5F shows a ceramic green sheet 212 for side surface formed to an edge portion of the side surface of the multilayer body 210.

Then, the multilayer body 210 may be rotated, and a second side edge portion may be formed on a second side surface of the multilayer body 210.

Then, the multilayer body 210 having the first and second side edge portions respectively formed on the opposite side surfaces thereof may be fired and sintered to form a ceramic main body including the dielectric layers and the first and second internal electrodes.

According to another exemplary embodiment of the present disclosure, a binder is applied to the ceramic green sheets 212 for side surfaces differently from the related art, and thus the ceramic green sheets 212 for side surfaces may be transferred to the side surfaces of the multilayer body 210 under low temperature and low pressure conditions.

Accordingly, damage to the multilayer body 210 can be significantly reduced, so that deterioration of electrical characteristics of the multilayer ceramic capacitor after sintering can be prevented and reliability of the multilayer ceramic capacitor can be improved.

Further, the ceramic green sheet 212 for side surface coated with the binder may be transferred to a side surface of the multilayer body 210 and pressed in a sintering process to increase close adhesion between the multilayer body and the ceramic green sheet for side surface.

Then, external electrodes may be formed on the third side surface of the ceramic body exposing the first internal electrodes and the fourth side surface of the ceramic body exposing the second internal electrodes, respectively.

According to another exemplary embodiment of the present disclosure, the thickness of the ceramic green sheets for the side surfaces may be small and the deviation of the thickness of the ceramic green sheets for the side surfaces may be small, so that a large-sized capacitance forming part may be secured.

In detail, the average thickness tc of each of the first and second side edge portions 112 and 113 after sintering may be 10 μm or more and 45 μm or less, and the deviation of the thickness of each of the first and second side edge portions 112 and 113 at each position may be small, so that a large-sized capacitance forming portion may be ensured and the moisture-proof reliability may be excellent.

Thus, a high-capacitance multilayer ceramic capacitor can be realized.

To avoid repetitive description, description of the same features as those in the above-described exemplary embodiments in the present disclosure will be omitted.

Hereinafter, the present disclosure will be described in more detail by experimental examples. However, the experimental examples are only to help the detailed understanding of the present disclosure, and the scope of the present disclosure is not limited by the experimental examples.

Examples of the tests

The multilayer ceramic capacitors according to invention examples 1 and 2 were manufactured such that the average thickness tc of each of the first side edge portion 112 and the second side edge portion 113 was 10 μm and 25 μm, respectively, and the multilayer ceramic capacitor according to the comparative example was manufactured such that the average thickness of each of the first side edge portion and the second side edge portion was 45 μm.

Further, as in the comparative example and the invention example, a ceramic green sheet multilayer body was formed, and a side edge portion was formed by attaching ceramic green sheets for side surfaces to an electrode exposed portion of the ceramic green sheet multilayer body having no edge due to exposure of internal electrodes in the width direction.

A multilayer ceramic capacitor green sheet having 0603 dimensions (length × width × height of 0.6mm × 0.3mm × 0.3mm) was manufactured by attaching ceramic green sheets for side surfaces to opposite side surfaces of a ceramic green sheet multilayer body by applying predetermined temperature and pressure under conditions that significantly suppress deformation of the sheet.

The multilayer ceramic capacitor samples manufactured as described above were subjected to a calcination process at a temperature of 400 ℃ or less in a nitrogen atmosphere, and 0.5% H at a sintering temperature of 1200 ℃ or less₂Or lower H₂Sintering is performed under the condition of hydrogen concentration of (1). Then, the moisture permeability of the multilayer ceramic capacitor sample was confirmed.

The measurement of moisture vapor permeability was performed by observing the multilayer ceramic capacitors according to the comparative example and inventive examples 1 and 2 at a temperature of 160 ℃ and a relative humidity of 90% for 300 minutes.

[ Table 1]

	Thickness of side edge part (μm)	Moisture vapor transmission rate (wt%)
			Inventive example 1	10	0.001
Inventive example 2	25	0.002
			Comparative example	45	0.783

As a result of measurement of the above test, it can be seen that in inventive example 1 and inventive example 2, the moisture vapor permeability has a value almost close to 0, so that the moisture proof reliability is excellent.

On the other hand, it can be seen that in the comparative example, the moisture permeability is high (0.783 wt%), so that the moisture-proof reliability is low.

This proves that, in the comparative example, in the case where the multilayer ceramic capacitor was manufactured such that the average thickness of each of the first side edge portion and the second side edge portion was 45 μm or more, sufficient sintering was not performed such that pores were generated in the interior and the surface of each of the side edge portions, and thus moisture penetrated into the multilayer ceramic capacitor.

As set forth above, according to exemplary embodiments in the present disclosure, the thickness of the side edge portion disposed on the side surface of the ceramic main body may be controlled to prevent penetration of moisture, thereby improving moisture-proof reliability.

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

Claims (13)

1. A multilayer ceramic capacitor, comprising:

a ceramic body including a dielectric layer and having first and second surfaces opposite to each other, third and fourth surfaces connecting the first and second surfaces to each other, and fifth and sixth surfaces connected to the first to fourth surfaces and opposite to each other;

a plurality of internal electrodes disposed in the ceramic body, exposed to the first surface and the second surface, and having one end exposed to the third surface or the fourth surface; and

first and second side edge portions provided on the first and second surfaces of the ceramic main body, respectively, exposing the internal electrodes,

wherein a thickness of each of the first side edge portion and the second side edge portion is 10 μm or more and less than 45 μm.

2. The multilayer ceramic capacitor according to claim 1, wherein a ratio of a thickness of a region of the first side edge portion or the second side edge portion that is in contact with an end of an internal electrode disposed at an outermost portion of the ceramic main body in a direction in which the plurality of internal electrodes are stacked to a thickness of a region of the first side edge portion or the second side edge portion that is in contact with an end of an internal electrode of the plurality of internal electrodes disposed in a central portion of the ceramic main body in the direction in which the plurality of internal electrodes are stacked is 0.9 or more and 1.0 or less.

3. The multilayer ceramic capacitor according to claim 1, wherein a ratio of a thickness of a region of the first side edge portion or the second side edge portion that is in contact with an edge of the ceramic main body to a thickness of a region of the first side edge portion or the second side edge portion that is in contact with a tip of one of the plurality of internal electrodes disposed in a central portion of the ceramic main body in a direction in which the plurality of internal electrodes are stacked is 0.9 or more and 1.0 or less.

4. The multilayer ceramic capacitor according to claim 1, wherein the dielectric layer has a thickness of 0.4 μm or less, and the internal electrode has a thickness of 0.4 μm or less.

5. The multilayer ceramic capacitor according to claim 1, wherein the ceramic main body includes an effective portion in which a capacitance is formed by including the plurality of internal electrodes disposed facing each other with the dielectric layer interposed therebetween, and cover portions which are respectively formed on upper and lower surfaces of the effective portion and between which the dielectric layer is interposed, and the cover portions are respectively formed

The thickness of the covering part is 20 μm or less.

6. The multilayer ceramic capacitor according to claim 1, wherein the number of the plurality of internal electrodes is 400 or more.

7. A method of manufacturing a multilayer ceramic capacitor, the method comprising:

preparing first ceramic green sheets having a plurality of first internal electrode patterns formed thereon at predetermined intervals and second ceramic green sheets having a plurality of second internal electrode patterns formed thereon at predetermined intervals;

forming a ceramic green sheet multilayer body by stacking the first ceramic green sheet and the second ceramic green sheet such that the first internal electrode pattern and the second internal electrode pattern are overlapped with each other;

cutting the multilayer body of ceramic green sheets to have side surfaces exposing ends of the first and second internal electrode patterns in a width direction;

forming first and second side edge portions on the side surfaces exposing the ends of the first and second internal electrode patterns, respectively; and

preparing a ceramic body including dielectric layers and internal electrodes by sintering the cut multilayer body of the ceramic green sheets,

wherein a thickness of each of the first side edge portion and the second side edge portion is 10 μm or more and less than 45 μm.

8. The method according to claim 7, wherein each of the first and second ceramic green sheets has a thickness of 0.6 μm or less, and each of the first and second internal electrode patterns has a thickness of 0.5 μm or less.

9. The method according to claim 7, wherein a ratio of a thickness of a region of the first side edge portion or the second side edge portion that is in contact with a tip of an internal electrode disposed at an outermost portion of the ceramic main body in the direction in which the internal electrodes are stacked to a thickness of a region of the first side edge portion or the second side edge portion that is in contact with a tip of an internal electrode disposed at a central portion of the ceramic main body in the direction in which the internal electrodes are stacked is 0.9 or more and 1.0 or less.

10. The method according to claim 7, wherein a ratio of a thickness of a region of the first side edge portion or the second side edge portion that is in contact with an edge of the ceramic main body to a thickness of a region of the first side edge portion or the second side edge portion that is in contact with a tip of one of the internal electrodes disposed in a central portion of the ceramic main body in a direction in which the internal electrodes are stacked is 0.9 or more and 1.0 or less.

11. The method according to claim 7, wherein the ceramic main body includes an effective portion in which a capacitance is formed by including the internal electrodes disposed to face each other with the dielectric layer interposed therebetween, and cover portions formed on upper and lower surfaces of the effective portion, respectively, and

the thickness of the covering part is 20 μm or less.

12. The method of claim 7, wherein the number of inner electrodes is 400 or greater.

13. The method according to claim 7, wherein the first side edge portion is formed by transferring a portion of a third ceramic green sheet to one of the side surfaces of the cut multilayer ceramic green sheet, and the second side edge portion is formed by transferring a portion of a fourth ceramic green sheet to another one of the side surfaces of the cut multilayer ceramic green sheet.

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