KR20220053455A - Ceramic electronic component - Google Patents

Abstract

A ceramic electronic component according to one embodiment of the present invention comprises: a body comprising a dielectric layer and an internal electrode; and an external electrode disposed on the body and connected to the internal electrode, wherein the dielectric layer comprises a plurality of crystal grains and a crystal grain boundary disposed between the adjacent crystal grains, and a ratio (C2/C1) of an Mg content (C1) of the crystal grain to an Mg content (C2) of the crystal grain boundary is 3 or more. Therefore, the present invention is capable of improving a reliability.

Description

Ceramic electronic component {CERAMIC ELECTRONIC COMPONENT}

The present invention relates to a ceramic electronic component.

Multi-Layered Ceramic Capacitors (MLCCs), one of ceramic electronic components, are used in imaging devices such as liquid crystal displays (LCDs) and plasma display panels (PDPs), computers, and smartphones. and a chip-type capacitor mounted on a printed circuit board of various electronic products, such as cell phones, to charge or discharge electricity.

Such multilayer ceramic capacitors may be used as components of various electronic devices due to their small size, high capacity, and easy mounting. Recently, as various electronic devices such as computers and mobile devices are miniaturized and have high output, the demand for miniaturization and high capacity of multilayer ceramic capacitors is also increasing.

In order to achieve miniaturization and high capacity of the multilayer ceramic capacitor, it is necessary to increase the number of stacks by reducing the thickness of the dielectric layer and the internal electrode. Currently, the thickness of the dielectric layer has reached the level of about 0.6 μm, and thinning continues. However, as the thickness of the dielectric layer decreases, the electric field applied to the dielectric at the same operating voltage increases, so it is essential to secure the reliability of the dielectric.

One of several objects of the present invention is to provide a ceramic electronic component having excellent reliability.

One of several objects of the present invention is to provide a ceramic electronic component having improved insulation resistance.

One of several objects of the present invention is to provide a ceramic electronic component having excellent high-temperature reliability.

However, the object of the present invention is not limited to the above, and will be more easily understood in the course of describing specific embodiments of the present invention.

A ceramic electronic component according to an embodiment of the present invention includes a body including a dielectric layer and an internal electrode; and an external electrode disposed on the body and connected to the internal electrode. including, wherein the dielectric layer includes a plurality of dielectric grains and grain boundaries disposed between adjacent dielectric grains, and the ratio (C2/C1) of the Mg content (C1) of the grain boundaries to the Mg content (C2) of the grain boundaries is 3 More than that.

As one effect among various effects of the present invention, reliability may be improved by disposing Mg at the dielectric grain boundary.

However, various and beneficial advantages and effects of the present invention are not limited to the above, and will be more easily understood in the course of describing specific embodiments of the present invention.

1 schematically illustrates a perspective view of a ceramic electronic component according to an embodiment of the present invention.
FIG. 2 schematically illustrates a cross-sectional view II′ of FIG. 1 .
FIG. 3 schematically illustrates a cross-sectional view taken along II-II′ of FIG. 1 .
4 is an exploded perspective view schematically illustrating an exploded body of a ceramic electronic component according to an embodiment of the present invention.
FIG. 5 is an enlarged view of region P of FIG. 2 .
6 is an SEM-EDS mapping image taken at a magnification of 9900 at the center of the cross section in the length and thickness directions cut from the center in the width direction of Test No. 1;
7 is an SEM-EDS mapping image taken at a magnification of 9900 at the center of the cross section in the length and thickness directions cut from the center in the width direction of Test No. 2;
8 is a STEM-HAADF image in which grain boundaries stand parallel to an electron beam.
9 is a graph (IV curve) showing the amount of change in leakage current according to the applied voltage for Test Nos. 1 and 2;
10 is a graph showing the Weibull distribution of BDV for Test Nos. 1 and 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to specific embodiments and the accompanying drawings. However, the embodiment of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. Further, the embodiments of the present invention are provided in order to more completely explain the present invention to those skilled in the art. Accordingly, the shapes and sizes of elements in the drawings may be exaggerated for clearer description, and elements indicated by the same reference numerals in the drawings are the same elements.

And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and the size and thickness of each component shown in the drawings are arbitrarily indicated for convenience of description, so the present invention is not necessarily limited to the illustrated bar. . In addition, components having the same function within the scope of the same concept will be described using the same reference numerals. Furthermore, throughout the specification, when a part "includes" a certain element, it means that other elements may be further included, rather than excluding other elements, unless otherwise stated.

In the drawings, a first direction may be defined as a stacking direction or a thickness (T) direction, a second direction may be defined as a length (L) direction, and a third direction may be defined as a width (W) direction.

ceramic electronic components

1 schematically illustrates a perspective view of a ceramic electronic component according to an embodiment of the present invention.

FIG. 2 schematically illustrates a cross-sectional view taken along line II′ of FIG. 1 .

FIG. 3 schematically illustrates a cross-sectional view taken along II-II′ of FIG. 1 .

4 is an exploded perspective view schematically illustrating an exploded body of a ceramic electronic component according to an embodiment of the present invention.

FIG. 5 is an enlarged view of region P of FIG. 2 .

Hereinafter, a ceramic electronic component 100 according to an exemplary embodiment of the present invention will be described in detail with reference to FIGS. 1 to 5 . In addition, a multi-layered ceramic capacitor (hereinafter referred to as 'MLCC') will be described as an example of a ceramic electronic component, but the present invention is not limited thereto, and various ceramic electronic components using a ceramic material, for example For example, it may be applied to an inductor, a piezoelectric element, a varistor, or a thermistor.

A ceramic electronic component 100 according to an embodiment of the present invention includes a body 110 including a dielectric layer 111 and internal electrodes 121 and 122 ; and external electrodes 131 and 132 disposed on the body and connected to the internal electrodes; including, wherein the dielectric layer 111 includes a plurality of grains 111a and a grain boundary 111b disposed between adjacent grains, and the ratio of the Mg content of the grain boundaries to the Mg content of the grains (C1) (C2) (C2/C1) is 3 or more.

In the body 110 , a dielectric layer 111 and internal electrodes 121 and 122 may be alternately stacked.

Although the specific shape of the body 110 is not particularly limited, as shown, the body 110 may have a hexahedral shape or a shape similar thereto. Due to the shrinkage of the ceramic powder included in the body 110 during the firing process, the body 110 may not have a perfectly straight hexahedral shape, but may have a substantially hexahedral shape.

The body 110 includes first and second surfaces 1 and 2 facing each other in a first direction, and third and third surfaces connected to the first and second surfaces 1 and 2 and facing each other in a second direction. 4 surfaces 3 and 4, fifth and sixth surfaces connected to the first and second surfaces 1 and 2 and connected to the third and fourth surfaces 3 and 4 and facing each other in the third direction ( 5, 6) may have.

The plurality of dielectric layers 111 forming the body 110 are in a fired state, and the boundary between adjacent dielectric layers 111 can be integrated to the extent that it is difficult to check without using a scanning electron microscope (SEM). there is.

The dielectric layer 111 includes a plurality of grains 111a and a grain boundary 111b disposed between adjacent grains, and the ratio of the Mg content of the grain boundary (C1) to the Mg content of the grain boundary (C2) (C2/C1) may be 3 or more.

A multi-layer ceramic capacitor (MLCC), which is one of ceramic electronic components, tends to have a higher capacity and a thinner layer. As the thickness of the dielectric layer decreases, the electric field applied to the dielectric at the same operating voltage increases. Therefore, it is essential to secure the reliability of the dielectric.

The most important indicator of dielectric reliability is insulation resistance (IR), and studies on the degradation behavior of insulation resistance have been actively conducted to secure reliability of MLCC. The main component constituting the insulation resistance is known as the grain boundary resistance due to the Schottky type energy barrier existing at the dielectric grain boundary (grain boundary). Since grain boundary resistance is a major variable that determines insulation resistance, technology development has been made in the direction of increasing the number of grain boundaries by suppressing grain growth in order to improve MLCC reliability. However, when grain growth is suppressed, it is difficult to achieve high capacity due to a decrease in dielectric constant.

Therefore, in the present invention, it is intended to improve reliability by controlling the composition of grain boundaries without excessively suppressing grain growth. The grain boundary resistance may be generated by positive ions present at the dielectric grain boundary. A space charge layer is formed by the cations that are precipitated or not dissolved at the grain boundary, and the grain boundary resistance increases by creating an energy barrier. Therefore, the grain boundary resistance can be strengthened by lowering the solubility of the additive added to control the BaTiO ₃ (BT) dielectric properties.

Mg may be distributed at grain boundaries or in the shell region of dielectric grains having a core-shell structure to inhibit other elements from being dissolved into the dielectric grains. According to an embodiment of the present invention, by setting the ratio (C2/C1) of the Mg content (C1) of the grains to the Mg content (C2) of the grain boundaries to be 3 or more, the other elements are dielectrics without excessively suppressing grain growth. It is possible to suppress the solid solution into the crystal grains, thereby improving the grain boundary resistance.

When the ratio (C2/C1) of the Mg content (C2) of the grain boundary to the Mg content (C1) of the grains is less than the effect of improving the grain boundary resistance due to Mg and preventing other additives from being dissolved into the grains, the effect may be insufficient. .

On the other hand, the upper limit of the ratio (C2/C1) of the Mg content (C2) of the grain boundary to the Mg content of the grain (C1) does not need to be particularly limited, but the Mg content of the grain boundary (C2) compared to the Mg content of the grain (C1) When the ratio (C2/C1) of is greater than 10, the effect of improving the grain boundary resistance and preventing other additives from being dissolved into the crystal grains may be saturated. Therefore, it may be preferable that the upper limit of the ratio (C2/C1) of the Mg content (C1) of the grain boundary to the Mg content (C2) of the grain boundary is 10.

Here, the Mg content of the grains (C1) and the Mg content of the grain boundaries (C2) are averaged by analyzing the composition of 10 random positions in each of the three dielectric layers disposed in the center of the body in the length and thickness directions using STEM-EDS. can be a value. Referring to FIG. 5 , the Mg content (C2) of the grain boundary may be measured at a position marked with ○, which is the center of the grain boundary, and the Mg content (C1) of the grain boundary is 30 nm apart from the center of the grain boundary in the direction perpendicular to the grain boundary. It may be measured at the position marked with X, which is the The center of the grain boundary may mean a position with the highest Mg content as a result of performing a line-profile using STEM-EDS in a direction perpendicular to the grain boundary.

In one embodiment, the Mg content (C2) of the grain boundary is the Mg content at the center of the grain boundary, and the Mg content (C1) of the grain boundary is the Mg content at a position spaced from the center of the grain boundary by 30 nm in a direction perpendicular to the grain boundary. .

In this case, the Mg content (C2) of the grain boundary may be 0.2 at% or more and 0.6 at% or less, and preferably 0.25 at% or more and 0.55 at% or less.

In addition, the Mg content (C1) of the grains may be 0.01 at% or more and 0.15 at% or less, and preferably 0.05 at% or more and 0.1 at% or less.

The method of controlling the ratio (C2/C1) of the Mg content (C1) of the grain boundary to the Mg content (C2) of the grain boundary to 3 or more does not need to be particularly limited. However, in general, when Mg is added to the dielectric composition in the form of MgO, since MgO is more readily dissolved in NiO than BaTiO ₃ , Ni-Mg-O secondary phase is formed and agglomerated in an atmosphere where the Ni internal electrode can be oxidized. Therefore, it may be difficult to distribute Mg at grain boundaries, and accordingly, the effect of suppressing the solid solution of other elements into dielectric grains may be insignificant. Therefore, by proceeding firing in a firing atmosphere in which Ni cannot be thermodynamically oxidized, oxidation of the Ni internal electrode is prevented, and Mg is prevented from forming or segregating the Ni-Mg-O secondary phase, thereby uniformly distributing Mg at grain boundaries. The ratio (C2/C1) of the Mg content (C1) of the grain boundary to the Mg content (C2) of the grain boundary may be controlled to 3 or more.

In one embodiment, the internal electrodes 121 and 122 and the dielectric layer 111 may not include a Ni-Mg-O secondary phase. This is because, when the Ni-Mg-O secondary phase is formed, it may be difficult to distribute Mg at grain boundaries, and accordingly, the effect of suppressing the solid solution of other elements into the dielectric grains may be insignificant.

Here, the presence or absence of the Ni-Mg-O secondary phase can be confirmed from the SEM-EDS mapping image taken at 9900 magnification of the central portion of the cross-section in the length and thickness direction cut from the center in the width direction as shown in FIGS. 6 and 7, and in FIG. When a region in which Mg is segregated with a size of 10 nm or more present in the circled portion is observed, it can be determined that a Ni-Mg-O secondary phase exists.

In an embodiment, the grain boundary 111b may further include Dy. In this case, the Dy content does not need to be particularly limited, but preferably, the Dy content may be 0.5 at% or more and 2.0 at% or less, and more preferably 0.7 at% or more and 1.8 at% or less. Dy may also be included in the grains, but according to the present invention, when Mg is contained at the grain boundary compared to the grains according to the present invention, it is possible to suppress the dissolution of Dy into the dielectric grains, so the Dy content in the grains may be 0.5 at% or less. .

In an embodiment, the grain boundary 111b may further include Si. In this case, the Si content does not need to be particularly limited, but preferably, the Si content may be 1.0 at% or more and 5.0 at% or less, and more preferably, the Si content may be 1.6 at% or more and 3.7 at% or less. Si may also be included in the grains, but according to the present invention, when Mg is contained at the grain boundary compared to the grains according to the present invention, it is possible to suppress the Si from being dissolved into the dielectric grains, so the Si content in the grains may be 0.5 at% or less. .

In an embodiment, at least one of the plurality of grains may have a core-shell structure. When the grains have a core-shell structure, the Mg content (C1) of the grains may mean the Mg content in the shell region. it could be That is, the ratio of the Mg content of the grain boundary to the Mg content of the shell may be 3 or more.

In addition, the Mg content of the core may be 0.01 at% or less. The Mg content of the core may be measured at the center of the core region.

In one embodiment, the dielectric layer 111 may include BaTiO ₃ as a main component.

Meanwhile, the thickness td of the dielectric layer 111 does not need to be particularly limited.

However, in general, when the dielectric layer is thinly formed to a thickness of less than 0.6 μm, in particular, when the thickness of the dielectric layer is 0.5 μm or less, there is a fear that reliability may be deteriorated.

As described above, according to one embodiment of the present invention, the Mg content (C1) of the grain boundary to the Mg content (C2) of the grain boundary (C2/C1) is 3 or more to induce the Mg grain boundary distribution, thereby increasing the grain boundary resistance and reliability can be improved, so that excellent reliability can be secured even when the thickness of the dielectric layer 111 is 0.5 μm or less.

Accordingly, when the thickness of the dielectric layer 111 is 0.5 μm or less, the reliability improvement effect according to the present invention may be more remarkable.

The thickness td of the dielectric layer 111 may mean an average thickness of the dielectric layer 111 disposed between the first and second internal electrodes 121 and 122 .

The average thickness of the dielectric layer 111 may be measured by scanning an image of the length and thickness direction (L-T) cross-section of the body 110 with a scanning electron microscope (SEM).

For example, in the image scanned with a scanning electron microscope (SEM) of cross-sections in the first and second directions (length and thickness directions) cut from the central portion of the body 110 in the third direction (width direction) For any of the extracted dielectric layers, the average value can be determined by measuring the thickness at 30 points equally spaced in the longitudinal direction.

The thickness measured at the 30 points at equal intervals may be measured in the capacitor forming part Ac indicating a region where the first and second internal electrodes 121 and 122 overlap each other.

The body 110 is disposed inside the body 110 and includes a first internal electrode 121 and a second internal electrode 122 disposed to face each other with a dielectric layer 111 interposed therebetween, so that a capacitance is formed. It may include a capacitor forming part Ac and cover parts 112 and 113 formed on upper and lower portions of the capacitor forming part Ac in the first direction.

In addition, the capacitor forming part Ac is a part contributing to the capacitance formation of the capacitor, and may be formed by repeatedly stacking the plurality of first and second internal electrodes 121 and 122 with the dielectric layer 111 interposed therebetween. there is.

The cover parts 112 and 113 include an upper cover part 112 disposed above the capacitor forming part Ac in the first direction and a lower cover part 113 disposed below the capacitor forming part Ac in the first direction. ) may be included.

The upper cover part 112 and the lower cover part 113 may be formed by stacking a single dielectric layer or two or more dielectric layers on the upper and lower surfaces of the capacitor forming part Ac in the thickness direction, respectively, and are basically resistant to physical or chemical stress. It can serve to prevent damage to the internal electrode by the

The upper cover part 112 and the lower cover part 113 do not include an internal electrode and may include the same material as the dielectric layer 111 .

That is, the upper cover part 112 and the lower cover part 113 may include a ceramic material, for example, a barium titanate (BaTiO ₃ )-based ceramic material.

Meanwhile, the thickness of the cover portions 112 and 113 does not need to be particularly limited. However, in order to more easily achieve miniaturization and high capacity of the ceramic electronic component, the thickness tp of the cover parts 112 and 113 may be 20 μm or less.

In addition, margin portions 114 and 115 may be disposed on a side surface of the capacitance forming portion Ac.

The margin portions 114 and 115 may include a margin portion 114 disposed on the fifth surface 5 of the body 110 and a margin portion 115 disposed on the sixth surface 6 of the body 110 . That is, the margin portions 114 and 115 may be disposed on both sides of the ceramic body 110 in the width direction.

As shown in FIG. 3 , the margin portions 114 and 115 include both ends of the first and second internal electrodes 121 and 122 and the body in a cross-section cut in the width-thickness (W-T) direction of the body 110 . (110) may mean a region between the boundary surfaces.

The margins 114 and 115 may basically serve to prevent damage to the internal electrode due to physical or chemical stress.

The margin portions 114 and 115 may be formed by forming internal electrodes by applying a conductive paste on the ceramic green sheet except where the margin portion is to be formed.

In addition, in order to suppress the step difference due to the internal electrodes 121 and 122, after lamination, the internal electrodes are cut to be exposed to the fifth and sixth surfaces 5 and 6 of the body, and then a single dielectric layer or two or more dielectric layers are formed. The margin portions 114 and 115 may be formed by stacking on both side surfaces of the capacitance forming portion Ac in the width direction.

The internal electrodes 121 and 122 are alternately stacked with the dielectric layer 111 .

The internal electrodes 121 and 122 may include first and second internal electrodes 121 and 122 . The first and second internal electrodes 121 and 122 are alternately disposed to face each other with the dielectric layer 111 constituting the body 110 interposed therebetween, and the third and fourth surfaces 3 and 4 of the body 110 . ) can be exposed respectively.

Referring to FIG. 2 , the first internal electrode 121 is spaced apart from the fourth surface 4 and exposed through the third surface 3 , and the second internal electrode 122 is spaced apart from the third surface 3 . and may be exposed through the fourth surface 4 .

In this case, the first and second internal electrodes 121 and 122 may be electrically separated from each other by the dielectric layer 111 disposed in the middle.

Referring to FIG. 4 , the body 110 may be formed by alternately stacking a ceramic green sheet on which the first internal electrode 121 is printed and a ceramic green sheet on which the second internal electrode 122 is printed, followed by firing. .

The internal electrodes 121 and 122 may include Ni. However, the material for forming the internal electrodes 121 and 122 is not particularly limited, and a material having excellent electrical conductivity may be used. For example, the internal electrodes 121 and 122 may include nickel (Ni), copper (Cu), palladium (Pd), silver (Ag), gold (Au), platinum (Pt), tin (Sn), or tungsten (W). ), titanium (Ti), and may include one or more of alloys thereof.

In addition, the internal electrodes 121 and 122 are nickel (Ni), copper (Cu), palladium (Pd), silver (Ag), gold (Au), platinum (Pt), tin (Sn), tungsten (W), It may be formed by printing a conductive paste for internal electrodes including at least one of titanium (Ti) and an alloy thereof on a ceramic green sheet. The printing method of the conductive paste for internal electrodes may use a screen printing method or a gravure printing method, but the present invention is not limited thereto.

Meanwhile, the thickness te of the internal electrodes 121 and 122 does not need to be particularly limited.

However, in general, when the internal electrode is thinly formed to a thickness of less than 0.6 μm, in particular, when the thickness of the internal electrode is 0.5 μm or less, reliability may be deteriorated.

As described above, according to one embodiment of the present invention, the Mg content (C1) of the grain boundary to the Mg content (C2) of the grain boundary (C2/C1) is 3 or more to induce the Mg grain boundary distribution, thereby increasing the grain boundary resistance and reliability can be improved, excellent reliability can be secured even when the thickness of the internal electrodes 121 and 122 is 0.5 μm or less.

Therefore, when the thickness of the internal electrodes 121 and 122 is 0.5 μm or less, the effect according to the present invention may be more remarkable, and miniaturization and high capacity of the ceramic electronic component may be more easily achieved.

The thickness te of the internal electrodes 121 and 122 may mean an average thickness of the internal electrodes 121 and 122 .

The average thickness of the internal electrodes 121 and 122 may be measured by scanning an image of the length and thickness direction (L-T) cross-section of the body 110 with a scanning electron microscope (SEM).

For example, in the image scanned with a scanning electron microscope (SEM) of cross-sections in the first and second directions (length and thickness directions) cut from the central portion of the body 110 in the third direction (width direction) With respect to the extracted arbitrary first and second internal electrodes 121 and 122, the thickness may be measured at 30 equal intervals in the longitudinal direction to measure the average value.

The 30 equally spaced points may be measured in the capacitor forming part Ac, which means a region where the internal electrodes 121 and 122 overlap each other.

The external electrodes 131 and 132 may be disposed on the third surface 3 and the fourth surface 4 of the body 110 .

The external electrodes 131 and 132 are respectively disposed on the third and fourth surfaces 3 and 4 of the body 110 , respectively, and first and second external electrodes connected to the first and second internal electrodes 121 and 122 , respectively. It may include electrodes 131 and 132 .

Referring to FIG. 1 , the external electrodes 131 and 132 may be disposed to cover both end surfaces of the side margin portions 114 and 115 in the second direction.

In the present embodiment, a structure in which the ceramic electronic component 100 has two external electrodes 131 and 132 is described. However, the number and shape of the external electrodes 131 and 132 depends on the shape of the internal electrodes 121 and 122 . or for other purposes.

On the other hand, the external electrodes 131 and 132 may be formed using any material as long as they have electrical conductivity, such as metal, and specific materials may be determined in consideration of electrical characteristics and structural stability, and furthermore, may have a multilayer structure. there is.

For example, the external electrodes 131 and 132 may include electrode layers 131a and 132a disposed on the body 110 and plating layers 131b and 132b formed on the electrode layers 131a and 132a.

As a more specific example of the electrode layers 131a and 132a, the electrode layers 131a and 132a may be a firing electrode including a conductive metal and glass, or a resin-based electrode including a conductive metal and a resin.

In addition, the electrode layers 131a and 132a may have a form in which a fired electrode and a resin-based electrode are sequentially formed on a body. In addition, the electrode layers 131a and 132a may be formed by transferring a sheet including a conductive metal onto the body or by transferring a sheet including a conductive metal onto the firing electrode.

As the conductive metal included in the electrode layers 131a and 132a, a material having excellent electrical conductivity may be used, but is not particularly limited. For example, the conductive metal may be one or more of nickel (Ni), copper (Cu), and alloys thereof.

The plating layers 131b and 132b serve to improve mounting characteristics. The type of the plating layers 131b and 132b is not particularly limited, and may be a plating layer including at least one of Ni, Sn, Pd, and alloys thereof, and may be formed of a plurality of layers.

As a more specific example of the plating layers 131b and 132b, the plating layers 131b and 132b may be a Ni plating layer or a Sn plating layer, and a Ni plating layer and a Sn plating layer may be sequentially formed on the electrode layers 131a and 132a. and a Sn plating layer, a Ni plating layer, and a Sn plating layer may be sequentially formed. In addition, the plating layers 131b and 132b may include a plurality of Ni plating layers and/or a plurality of Sn plating layers.

The size of the ceramic electronic component 100 does not need to be particularly limited.

However, in order to achieve miniaturization and high capacity at the same time, since it is necessary to increase the number of stacks by making the thickness of the dielectric layer and the internal electrode thin, the ceramic electronic component 100 having a size of 1005 (length × width, 1.0 mm × 0.5 mm) or less. In the reliability and insulation resistance improvement effect according to the present invention can be more remarkable.

Accordingly, in consideration of manufacturing errors and external electrode sizes, when the length of the ceramic electronic component 100 is 1.1 mm or less and the width is 0.55 mm or less, the reliability improvement effect according to the present invention may be more significant. Here, the length of the ceramic electronic component 100 may mean the size of the ceramic electronic component 100 in the second direction, and the width of the ceramic electronic component 100 may mean the size of the ceramic electronic component 100 in the third direction. there is.

Manufacturing method of ceramic electronic components

Hereinafter, a method of manufacturing a ceramic electronic component according to another aspect of the present invention will be described in detail. However, in order to avoid overlapping descriptions, content overlapping with those described in the ceramic electronic component will be omitted.

According to another aspect of the present invention, a method of manufacturing a ceramic electronic component includes: obtaining a ceramic green sheet using a dielectric composition including Mg; forming an internal electrode pattern by applying a conductive paste for internal electrodes on the ceramic green sheet; obtaining a laminate by laminating a plurality of ceramic green sheets on which the internal electrode patterns are formed; preparing a body including a dielectric layer and an internal electrode by sintering the laminate in a reducing atmosphere and then re-oxidizing it in a reducing atmosphere; and forming an external electrode on the body; wherein the electromotive force of the reducing atmosphere during firing is 50 mV or more higher than the Ni/NiO equilibrium partial voltage electromotive force, and is not higher than 90 mV than the Ni/NiO equilibrium partial voltage electromotive force.

First, a ceramic green sheet is obtained using a dielectric composition containing Mg.

In this case, the dielectric composition may include BaTiO ₃ as a main component, and may contain 0.2 to 3 moles of Mg based on 100 moles of BaTiO3. When the Mg content is less than 0.2 mol, it may be difficult to control the grain growth of BaTiO ₃ , and it may be difficult to control the ratio (C2/C1) of the Mg content (C1) of the grains to the Mg content (C2) of the grain boundaries to 3 or more. there is. On the other hand, when the Mg content is more than 3 mol, grain growth may be excessively suppressed.

The content of elements included as subcomponents other than Mg does not need to be particularly limited, and may be appropriately controlled to obtain desired properties.

For example, the dielectric composition may contain 0.5 to 2 moles of Dy relative to 100 moles of BaTiO ₃ as an auxiliary component. In addition, the dielectric composition may contain 1 to 5 moles of Si relative to 100 moles of BaTiO ₃ as an auxiliary component. In addition to this, commonly added sub-ingredients may be added.

At this time, after adding the subcomponents to the main component powder, ethanol and toluene as solvents are mixed with the dispersing agent, and then the binder is mixed to prepare a ceramic sheet. Meanwhile, Mg may be added in the form of MgO, Si may be added in the form of SiO 2 , and Dy may be added in the form of Dy ₂ O ₃ .

Next, after the conductive paste for internal electrodes is printed on the ceramic green sheet, it is laminated to obtain a laminate. In this case, the conductive paste for the internal electrode may include Ni.

Next, a multilayer body may be obtained by laminating a plurality of ceramic green sheets on which the internal electrode patterns are formed. In this case, a process of cutting the laminate in chip units may be additionally performed.

Next, after the laminate is fired in a reducing atmosphere, it is reoxidized in a reducing atmosphere to prepare a body including a dielectric layer and an internal electrode.

The electromotive force of the reducing atmosphere during the firing may be higher than the Ni/NiO equilibrium partial pressure electromotive force by 50 mV or more, and may not be higher than 90 mV than the Ni/NiO equilibrium partial pressure electromotive force.

In general, the firing atmosphere is maintained at an oxygen partial pressure similar to the Ni/NiO equilibrium partial pressure in order to suppress the reduction of BaTiO ₃ as much as possible while preventing the oxidation of the Ni inner electrode of the MLCC. When maintaining the oxygen partial pressure similar to the Ni/NiO equilibrium partial pressure, it is difficult to completely prevent oxidation of the inner electrode of Ni, and Ni in the inner electrode may be partially oxidized to form NiO, and MgO is more easily soluble in NiO than BaTiO ₃ Because of this, a Ni-Mg-O secondary phase is formed and aggregated, making it difficult to distribute Mg at grain boundaries. Accordingly, it may be difficult to improve reliability because it is difficult to increase grain boundary resistance.

On the other hand, when the electromotive force of the reducing atmosphere during firing is higher than the Ni/NiO equilibrium partial voltage electromotive force by 50 mV or more, the Ni internal electrode cannot be thermodynamically oxidized. and Mg can be uniformly dispersed at grain boundaries. Accordingly, the ratio (C2/C1) of the Mg content (C1) of the grain boundary to the Mg content (C2) of the grain boundary can be controlled to 3 or more, thereby improving the grain boundary resistance and improving reliability.

However, when the electromotive force of the reducing atmosphere during firing is higher than the Ni/NiO equilibrium partial pressure electromotive force by more than 90 mV, oxygen vacancies are excessively formed and reliability deterioration may occur.

Ni/NiO equilibrium partial pressure electromotive force is an oxidation characteristic of Ni, which is an inherent property of a material and can be measured by constructing a solid electrochemical cell using an oxygen ion conductive ceramic such as yttria-stabilized zirconia (YSZ).

In one embodiment, the electromotive force of the reducing atmosphere during the reoxidation is equal to or greater than the Ni/NiO equilibrium partial pressure electromotive force, and may not be higher than 10 mV than the Ni/NiO equilibrium partial pressure electromotive force. In the reoxidation process, it may be desirable to proceed in an atmosphere similar to the equilibrium partial pressure as much as possible, since oxygen vacancies that are generated in the firing process and that may deteriorate reliability should be removed as much as possible. At this time, in order to fundamentally prevent Ni oxidation, since the reoxidation electromotive force should be maintained higher than the theoretical equilibrium electromotive force, it may be preferable to proceed with the reoxidation at a slightly higher electromotive force than the equilibrium point in the range of 10 mV.

Next, an external electrode may be formed on the body to obtain a ceramic electronic component.

(Experimental example)

After preparing a dielectric composition containing barium titanate (BaTiO ₃ ) as a main component and containing 1 mol of MgO, 3.375 mol of SiO ₂ and 0.8 mol of Dy ₂ O ₃ relative to 100 mol of BaTiO ₃ , a dielectric composition containing the dielectric composition was prepared. An internal electrode pattern was formed by applying a conductive paste for internal electrodes containing Ni on it. Then, the laminate obtained by laminating the ceramic green sheets on which the internal electrode patterns were formed was cut in chip units and then fired under the firing atmosphere conditions shown in Table 1 below. Then, re-oxidation heat treatment was performed to prepare a prototype multilayer ceramic capacitor (Proto-type MLCC).

The Mg and Dy contents of the dielectric grains and grain boundaries included in the dielectric layer were analyzed, and whether Ni-Mg-O secondary phase was formed was observed and described in Table 1 below. In addition, the results of the high-temperature accelerated life test are shown in Table 1 below.

Mg and Dy contents were measured using a scanning transmission electron microscope (STEM, FEI's Osiris model) equipped with an energy dispersive X-ray analysis equipment (EDS) under conditions of an acceleration voltage of 200 kV and a probe diameter of 1 nm.

First, a thinned specimen corresponding to a cross section cut in the length and thickness directions from the center of the body in the width direction was prepared using the microsampling method.

The composition of the grain boundary 111b was analyzed by observing the specimen with STEM to find the grain boundary standing parallel to the electron beam. Specifically, when the Fresnel fringes appearing when defocused in the STEM-HAADF image were observed symmetrically at both ends of the grain boundary as shown in FIG. 8, it was determined that the grain boundary stood parallel to the electron beam.

For the composition of the grains 111a, positions spaced apart by 30 nm from the center of the grain boundaries in a direction perpendicular to the grain boundaries were analyzed.

In the three dielectric layers disposed in the center of the body in the length and thickness directions, 10 random positions of grain boundaries and grains were analyzed using STEM-EDS, and the average values are shown in Table 1 below.

The presence or absence of the secondary phase in Table 1 below is determined in the STEM-EDS mapping image observed in the range of 10 μm x 10 μm in the central portion of the cross-section cut in the length and thickness directions from the central portion in the width direction of the body in the range of 10 μm x 10 μm, as shown in FIGS. 6 and 7 . O This is an analysis of the presence or absence of secondary phase formation.

For the high-temperature accelerated life test, 30 sample chips for each test number were prepared and a voltage of 9.45V was applied at 105°C for 12 hours, and the sample chips whose insulation resistance decreased to 1/10 or less of the initial value were judged as defective. and the number of chips determined to be defective.

exam
number firing
atmosphere
electromotive force
(mV) Ni/NiO
Equilibrium partial pressure
electromotive force
(mV) electromotive force
Difference Dy
(halitosis)
(at%) Dy
(Grain boundary)
(at%) Mg
(halitosis)
(at%) Mg
(Grain boundary)
(at%) Mg (grain boundary)/
Mg (in the mouth) secondary
existence and nonexistence High temperature
Acceleration
life span One 606 541 65 0.31 1.62 0.09 0.48 5.333 X 1/30 2* 516 543 -27 0.33 1.24 0.07 0.11 1.571 O 15/30 3 613 548 65 0.18 0.68 0.09 0.32 3.556 X 0/30 4* 514 541 -27 0.19 0.59 0.06 0.09 1.500 O 16/30 5 602 540 62 0.12 0.72 0.09 0.34 3.778 X 1/30 6* 506 529 -23 0.15 0.64 0.08 0.12 1.500 O 4/30

In Test Nos. 1, 3 and 5, which were fired in a firing atmosphere that is 50 mV or higher than the Ni/NiO equilibrium partial pressure electromotive force, Mg (grain boundary)/Mg (intragranular) is 3 or more, and Ni-Mg-O secondary phase is not observed, so Mg is at the grain boundary. It can be seen that they are evenly distributed. Accordingly, it can be confirmed that the high-temperature accelerated life characteristics are also excellent.

On the other hand, in Test Nos. 2, 4, and 6 calcined in a firing atmosphere that is less than 50 mV than the Ni/NiO equilibrium partial pressure electromotive force, Mg (grain boundary)/Mg (intragranular) was analyzed to be less than 3, and Ni-Mg-O secondary phase was observed. It can be confirmed that Mg is segregated. Accordingly, it can be confirmed that the high-temperature accelerated life characteristics are also inferior.

6 is an SEM-EDS mapping image taken at a magnification of 9900 at the center of the cross section in the length and thickness directions cut from the center in the width direction of Test No. 1; 7 is an SEM-EDS mapping image taken at a magnification of 9900 at the center of the cross section in the length and thickness directions cut from the center in the width direction of Test No. 2; In Test No. 1, the Ni-Mg-O secondary phase was not observed, but in Test No. 2, it can be confirmed that the Ni-Mg-O secondary phase was observed in the circled portion.

9 is a graph (I-V curve) showing the amount of change in leakage current according to the applied voltage for Test Nos. 1 and 2;

In order to precisely measure the amount of leakage current change according to the applied voltage, the voltage was applied in the form of a pulse by applying the stairway measurement method. At each voltage, the voltage was applied (charged) for 5 seconds and the current was measured after 5 seconds of discharge to measure the leakage at each voltage. The current was measured. If the change in leakage current according to voltage is represented by a double log graph (logI vs. logV), the Ohmic section in which IR does not deteriorate according to the slope (the section indicated by the dotted line with the slope of S1) and slow degradation due to the degradation of the intergranular resistance A section (a section indicated by a solid line having a slope of S2) and a section of rapid deterioration after the grain boundary resistance deteriorates can be distinguished. At this time, it can be determined that the grain boundary resistance is strengthened as the slow deterioration section due to the grain boundary resistance appears up to a high voltage.

As shown in the analysis result of FIG. 9 , it can be confirmed that the slow degradation section of Test No. 2 appears up to a high electric field, thereby delaying the entry into the fast degradation section. Therefore, it can be confirmed that the grain boundary resistance is strengthened when the Mg grain boundary distribution is induced through the firing atmosphere control.

10 is a graph showing the Weibull distribution of BDV for Test Nos. 1 and 2. It can be seen that the average value of BDV is 68V in Test No. 2 and 88V in Test No. 1, and it can be seen that the scale factor is also improved from 4.9 to 12.8, so that the dispersion is also improved.

Although the embodiment of the present invention has been described in detail above, the present invention is not limited by the above-described embodiment and the accompanying drawings, but is intended to be limited by the appended claims. Accordingly, various types of substitution, modification and change will be possible by those skilled in the art within the scope not departing from the technical spirit of the present invention described in the claims, and it is also said that it falls within the scope of the present invention. something to do.

100: ceramic electronic component
110: body
111: dielectric layer
111a: grains
111b: grain boundary
112, 113: cover part
114, 115: side margin part
121, 122: internal electrode
131, 132: external electrode
131a, 132a: electrode layer
131b, 132b: plating layer

Claims (17)

a body comprising a dielectric layer and an internal electrode; and
an external electrode disposed on the body and connected to the internal electrode; including,
The dielectric layer includes a plurality of grains and grain boundaries disposed between adjacent grains,
The ratio (C2/C1) of the Mg content (C1) of the grain boundary to the Mg content (C2) of the grain boundary is 3 or more
Ceramic electronic components.
According to claim 1,
wherein C2/C1 is 10 or less
Ceramic electronic components.
According to claim 1,
The Mg content (C2) of the grain boundary is the Mg content at the center of the grain boundary, and the Mg content (C1) of the grain boundary is the Mg content at a position spaced 30 nm from the center of the grain boundary in a direction perpendicular to the grain boundary.
Ceramic electronic components.
According to claim 1,
The dielectric layer and the internal electrode do not include a Ni-Mg-O-based secondary phase.
Ceramic electronic components.
According to claim 1,
The Mg content (C2) of the grain boundary is 0.2 at% or more and 0.6 at% or less.
Ceramic electronic components.
According to claim 1,
The Mg content (C1) of the grains is 0.01 at% or more and 0.15 at% or less
Ceramic electronic components.
According to claim 1,
At least one of the plurality of crystal grains has a core-shell structure,
The ratio of the Mg content of the grain boundary to the Mg content of the shell is 3 or more
Ceramic electronic components.
8. The method of claim 7,
The Mg content of the core is 0.01 at% or less
Ceramic electronic components.
According to claim 1,
The grain boundary further includes Dy, and the content of Dy is 0.5 at% or more and 2.0 at% or less.
Ceramic electronic components.
10. The method of claim 9,
The grain boundary further includes Si, and the content of Si is 1.0 at% or more and 5.0 at% or less.
Ceramic electronic components.
obtaining a ceramic green sheet using a dielectric composition including Mg;
forming an internal electrode pattern by applying a conductive paste for internal electrodes on the ceramic green sheet;
obtaining a laminate by laminating a plurality of ceramic green sheets on which the internal electrode patterns are formed;
preparing a body including a dielectric layer and an internal electrode by sintering the laminate in a reducing atmosphere and then re-oxidizing it in a reducing atmosphere; and
Including; forming an external electrode on the body;
The electromotive force of the reducing atmosphere during firing is 50mV or more higher than the Ni/NiO equilibrium partial pressure electromotive force, and is not higher than 90mV higher than the Ni/NiO equilibrium partial pressure electromotive force
A method for manufacturing a ceramic electronic component.
12. The method of claim 11,
The electromotive force of the reducing atmosphere during the reoxidation is equal to or greater than the Ni/NiO equilibrium partial voltage electromotive force, and is not higher than the Ni/NiO equilibrium partial pressure electromotive force by more than 10 mV
A method for manufacturing a ceramic electronic component.
12. The method of claim 11,
The dielectric layer includes a plurality of grains and grain boundaries disposed between adjacent grains,
The ratio (C2/C1) of the Mg content (C1) of the grain boundary to the Mg content (C2) of the grain boundary is 3 or more
A method for manufacturing a ceramic electronic component.
12. The method of claim 11,
The dielectric composition contains BaTiO ₃ as a main component, and contains 0.2 to 3 moles of Mg compared to 100 moles of BaTiO ₃
A method for manufacturing a ceramic electronic component.
12. The method of claim 11,
The conductive paste for the internal electrode contains Ni.
A method for manufacturing a ceramic electronic component.
12. The method of claim 11,
The dielectric composition contains 0.5 to 2 moles of Dy relative to 100 moles of BaTiO ₃
A method for manufacturing a ceramic electronic component.
17. The method of claim 16,
The dielectric composition contains 1 to 5 moles of Si relative to 100 moles of BaTiO ₃
A method for manufacturing a ceramic electronic component.

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