Multilayer ceramic capacitor

Abstract

A multilayer ceramic capacitor of the present disclosure may include: a ceramic body; the inner electrode is arranged inside the ceramic main body; and an outer electrode including a plating layer in contact with a surface of the ceramic body and connected to the inner electrode, in which a microcrack is present inward from a portion of the surface of the ceramic body in contact with the plating layer, and the microcrack may be filled with a metal forming the plating layer, and the portion of the surface of the ceramic body in contact with the plating layer may include an amorphous structure.

Description

Technical Field

[0001] The present disclosure relates to a multilayer ceramic capacitor. Background Art

[0002] Electronic components using ceramic materials include capacitors (such as multilayer ceramic capacitors), inductors, piezoelectric elements, varistors, thermistors, etc. Among these ceramic electronic components, multilayer ceramic capacitors (MLCCs) are used in various electronic devices due to their advantages of being small, ensuring high capacity, and being easy to mount.

[0003] For example, multilayer ceramic capacitors can be used as chip capacitors mounted on boards of various electronic products such as imaging devices (such as liquid crystal display (LCD) devices, plasma display panel (PDP) devices, and organic light emitting diodes (OLED)), computers, personal portable terminals, and smart phones to charge or discharge them.

[0004] A multilayer ceramic capacitor may include an inner electrode disposed inside a ceramic body and an outer electrode disposed outside the ceramic body and connected to the inner electrode. Typically, the outer electrode includes a base electrode formed by immersing the ceramic body in a conductive paste and blotting and a plating layer covering the base electrode. In this case, there is a problem that it is difficult to reduce the volume occupied by the outer electrode.

[0005] A metal thin film may be formed on the surface of a ceramic body and used as a seed layer to grow a plating layer, but there is a problem that the seed layer may peel or fall off during the plating process, resulting in poor plating. Summary of the invention

[0006] An aspect of the present disclosure is to provide a multilayer ceramic capacitor including external electrodes having a reduced volume.

[0007] Another aspect of the present disclosure is to provide a multilayer ceramic capacitor including an external electrode having a plating layer firmly bonded to a ceramic body.

[0008] However, the problems to be solved by the present disclosure are not limited to the above-mentioned problems, and can be expanded in various ways within the scope of the technical ideas included in the present disclosure.

[0009] According to an embodiment, a multilayer ceramic capacitor includes: a ceramic body; an inner electrode arranged inside the ceramic body; and an outer electrode including a plating layer contacting a surface of the ceramic body and connected to the inner electrode, wherein microcracks exist from a portion of the surface of the ceramic body contacting the plating layer to the inside, and the microcracks may be filled with a metal forming the plating layer, and the portion of the surface of the ceramic body contacting the plating layer may include an amorphous structure.

[0010] In one embodiment, the portion of the surface of the ceramic body in contact with the plating layer may include a bent portion.

[0011] In one embodiment, the curved portion includes an irregular pattern including repeated valleys and ridges, and an average period of the valleys or ridges may be greater than or equal to 0.1 μm and less than or equal to 8 μm, and an average amplitude of the valleys or ridges may be greater than or equal to 0.01 μm and less than or equal to 1 μm.

[0012] In one embodiment, the curved portion may include valleys and ridges, and microcracks may exist in the ridges.

[0013] In one embodiment, the depth of the microcracks may be greater than or equal to 10 nm and less than or equal to 1000 nm.

[0014] In one embodiment, the ceramic body may include barium (Ba) and titanium (Ti), and a ratio of the barium (Ba) content to the titanium (Ti) content (Ba / Ti) in the amorphous structure may be smaller than a ratio of the barium (Ba) content to the titanium (Ti) content (Ba / Ti) in the remaining area of ​​the surface of the ceramic body excluding the amorphous structure.

[0015] In one embodiment, the portion of the surface of the ceramic body in contact with the plating layer may have a resistance lower than a resistance of a portion of the surface of the ceramic body not in contact with the plating layer.

[0016] In one embodiment, the ratio of the resistance of the portion of the surface of the ceramic body that contacts the plating layer to the resistance of the portion of the surface of the ceramic body that does not contact the plating layer may be greater than or equal to 1 / 10. 4 And less than 1.

[0017] In one embodiment, the curved portion may include valleys and ridges, and a resistance of the ridges may be smaller than a resistance of the valleys.

[0018] In one embodiment, the thickness of the coating layer may be greater than 0 μm and less than or equal to 1 μm.

[0019] In one embodiment, the ceramic body may include a laser irradiated area formed by laser irradiation and a laser non-irradiated area not irradiated by the laser, wherein the laser irradiated area extends from a portion of the surface of the ceramic body in contact with the plating layer toward the interior of the ceramic body to a predetermined depth.

[0020] In one embodiment, the resistance of the laser irradiated area may be smaller than the resistance of the laser non-irradiated area.

[0021] In one embodiment, the ceramic body may include barium (Ba) and titanium (Ti), and a ratio of the barium (Ba) content to the titanium (Ti) content (Ba / Ti) in the amorphous structure in the laser irradiated region may be smaller than a ratio of the barium (Ba) content to the titanium (Ti) content (Ba / Ti) in the laser non-irradiated region.

[0022] In one embodiment, the laser irradiation area may include an outer layer portion and an inner layer portion, the outer layer portion may be a portion forming the outer surface of the laser irradiation area and in contact with the coating, the microcracks may exist in the outer layer portion, the inner layer portion may be a portion forming the inner surface of the laser irradiation area and in contact with the laser non-irradiated area, and microcracks may not exist in the inner layer portion.

[0023] In the multilayer ceramic capacitor according to the present embodiment, by reducing the volume of the external electrodes, the portion contributing to forming the capacitance can be made larger.

[0024] Furthermore, in the multilayer ceramic capacitor according to the present embodiment, the plating layers of the external electrodes can be firmly bonded to the ceramic body. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic perspective view of a multilayer ceramic capacitor according to an embodiment.

[0026] Figure 2 It is along Figure 1 A cross-sectional view taken along line II-II'.

[0027] Figure 3 yes Figure 1 Exploded perspective view of the multilayer structure of internal electrodes and dielectric layers in a multilayer ceramic capacitor.

[0028] Figure 4 It is laser irradiation Figure 1 A perspective view of a ceramic body of a multilayer ceramic capacitor.

[0029] Figure 5 yes Figure 2 Magnified view of area A.

[0030] Figure 6 yes Figure 4 A top plan view of a laser irradiated area of ​​a ceramic body of a multilayer ceramic capacitor.

[0031] Figure 7 yes Figure 6 Magnified view of area B in FIG.

[0032] Figure 8 It is shown Figure 7Figure 2. Measurement results of the shape of the bent portion.

[0033] Figures 9 to 12 A field emission (FE)-transmission electron microscope (TEM) analysis image and an energy dispersive spectroscopy (EDS) element analysis result according to an embodiment are shown. DETAILED DESCRIPTION

[0034] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings, and thus the embodiments can be easily implemented by a person skilled in the art to which the present disclosure belongs. The accompanying drawings and descriptions are considered to be illustrative and not restrictive in nature. Throughout the specification, the same or similar reference numerals represent the same or similar elements. In addition, some of the constituent elements in the accompanying drawings are enlarged, omitted or schematically shown, and the size of each constituent element does not fully reflect the actual size.

[0035] The drawings are only used to make the embodiments disclosed in this specification easy to understand, and the technical concepts disclosed in this specification are not limited to the drawings, and should be understood to include all changes, equivalents or alternatives included in the spirit and scope of the present disclosure.

[0036] Terms including ordinal numbers such as first, second, etc. may be used to describe elements of various structures, but the constituent elements are not limited by the terms. These terms are used only for the purpose of distinguishing one constituent element from other constituent elements.

[0037] It should be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, the element may be directly on the other element, or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements. In addition, throughout the specification, the term "on" a target element will be understood as being above or below the target element, and will not necessarily be understood as being on the "upper side" based on a direction opposite to the direction of gravity.

[0038] In this specification, terms such as "include" or "have" are intended to indicate the presence of features, quantities, steps, actions, constituent elements, parts or combinations thereof described in the specification, and therefore it should be understood that the possibility of the presence or addition of one or more other features, quantities, steps, actions, constituent elements, parts or combinations thereof is not precluded. In addition, unless explicitly described to the contrary, the words "include" or "have" will be understood to imply the inclusion of other constituent elements without excluding any other constituent elements.

[0039] Furthermore, throughout the specification, the phrase “on a plane” means observing a target portion from the top, and the phrase “on a cross section” means observing a cross section formed by vertically cutting the target portion from the side.

[0040] In addition, throughout the specification, “connected to” means not only that two or more constituent elements are directly connected, but also that two or more constituent elements are indirectly connected, physically connected and / or electrically connected through other constituent elements, or that two or more constituent elements are integrated and represented by different names according to position or function.

[0041] Figure 1 is a schematic perspective view of a multilayer ceramic capacitor according to an embodiment, Figure 2 It is along Figure 1 A cross-sectional view taken along line II-II', Figure 3 yes Figure 1 Exploded perspective view of the multilayer structure of internal electrodes and dielectric layers in a multilayer ceramic capacitor.

[0042] Reference Figure 1 , Figure 2 and Figure 3 , the multilayer ceramic capacitor 1000 according to the present embodiment includes a ceramic body 110 , a first external electrode 120 , a second external electrode 130 , a plurality of first internal electrodes 150 , and a plurality of second internal electrodes 160 .

[0043] First, in order to clearly describe the present embodiment, an L-axis direction, a W-axis direction, and a T-axis direction shown in the drawings represent a length direction, a width direction, and a thickness direction of the multilayer ceramic capacitor 1000, respectively.

[0044] The thickness direction (T-axis direction) may be a direction perpendicular to a wide surface (main surface) of a constituent element having a sheet shape such as the ceramic body 110. For example, the thickness direction (T-axis direction) may be used as the same concept as a direction in which dielectric layers are stacked.

[0045] The length direction (L-axis direction) may be a direction parallel to the wide surface (main surface) of the sheet-shaped component, that is, a direction intersecting (or orthogonal) with the thickness direction (T-axis direction). For example, the length direction (L-axis direction) may be a direction along which the first external electrode 120 and the second external electrode 130 are opposite to each other.

[0046] The width direction (W-axis direction) may be a direction parallel to the wide surface (main surface) of the sheet-shaped component, that is, a direction intersecting (or orthogonal to) both the thickness direction (T-axis direction) and the length direction (L-axis direction).

[0047] The ceramic body 110 may have a substantially hexahedral shape, but the present embodiment is not limited thereto. Due to shrinkage during sintering, the ceramic body 110 may not have a completely hexahedral shape, but may generally have a hexahedral shape. For example, the ceramic body 110 has a substantially cubic shape, but the corners or vertices may have a rounded shape.

[0048] In the present embodiment, for the convenience of description, the surfaces of the ceramic body 110 that are opposite to each other in the length direction (L-axis direction) are defined as the first surface S1 and the second surface S2, respectively. The surfaces of the ceramic body 110 that are opposite to each other in the width direction (W-axis direction) and connect the first surface S1 and the second surface S2 are defined as the third surface S3 and the fourth surface S4, respectively. The surfaces of the ceramic body 110 that are opposite to each other in the thickness direction (T-axis direction) and connect the first surface S1 and the second surface S2 and the third surface S3 and the fourth surface S4 are defined as the fifth surface S5 and the sixth surface S6, respectively.

[0049] Therefore, the first direction along which the first surface S1 and the second surface S2 are relative to each other can be the length direction (L-axis direction), and the second direction and the third direction perpendicular to the first direction and to each other can be the thickness direction (T-axis direction) and the width direction (W-axis direction), respectively, or the width direction (W-axis direction) and the thickness direction (T-axis direction), respectively.

[0050] Based on an optical microscope image or a scanning electron microscope (SEM) image of a cross section in the length direction (L axis direction) and the thickness direction (T axis direction) taken at the central portion in the width direction (W axis direction) of the ceramic body 110, the length of the ceramic body 110 may refer to: the maximum value among the lengths of a plurality of line segments connecting two outermost boundary lines and parallel to the length direction (L axis direction), the two outermost boundary lines being opposite to each other in the length direction (L axis direction) of the ceramic body 110 shown in the above cross-sectional image. In addition, the length of the ceramic body 110 may refer to: the minimum value among the lengths of a plurality of line segments connecting two outermost boundary lines and parallel to the length direction (L axis direction), the two outermost boundary lines being opposite to each other in the length direction (L axis direction) of the ceramic body 110 shown in the above cross-sectional image. On the other hand, the length of the ceramic body 110 may refer to the arithmetic mean of the lengths of at least two line segments among a plurality of line segments connecting two outermost boundary lines and parallel to the length direction (L-axis direction), wherein the two outermost boundary lines are opposite to each other in the length direction (L-axis direction) of the ceramic body 110 shown in the above-mentioned cross-sectional image.

[0051] Based on an optical microscope image or a scanning electron microscope (SEM) image of a cross section in the length direction (L axis direction) and the thickness direction (T axis direction) taken at the central portion of the ceramic body 110 in the width direction (W axis direction), the thickness of the ceramic body 110 may refer to the maximum value among the lengths of a plurality of line segments connecting two outermost boundary lines and parallel to the thickness direction (T axis direction), the two outermost boundary lines being opposite to each other in the thickness direction (T axis direction) of the ceramic body 110 shown in the above cross-sectional image. In addition, the thickness of the ceramic body 110 may refer to the minimum value among the lengths of a plurality of line segments connecting two outermost boundary lines and parallel to the thickness direction (T axis direction), the two outermost boundary lines being opposite to each other in the thickness direction (T axis direction) of the ceramic body 110 shown in the above cross-sectional image. On the other hand, the length of the ceramic body 110 may refer to the arithmetic mean of the lengths of at least two of a plurality of line segments connecting two outermost boundary lines and parallel to the thickness direction (T-axis direction), wherein the two outermost boundary lines are opposite to each other in the thickness direction (T-axis direction) of the ceramic body 110 shown in the above cross-sectional image.

[0052] Based on an optical microscope image or a scanning electron microscope (SEM) image of a cross section in the length direction (L axis direction) and the width direction (W axis direction) taken at the central portion of the ceramic body 110 in the thickness direction (T axis direction), the width of the ceramic body 110 may refer to the maximum value among the lengths of a plurality of line segments connecting two outermost boundary lines and parallel to the width direction (W axis direction), the two outermost boundary lines being opposite to each other in the width direction (W axis direction) of the ceramic body 110 shown in the above cross-sectional image. In addition, the width of the ceramic body 110 may refer to the minimum value among the lengths of a plurality of line segments connecting two outermost boundary lines and parallel to the width direction (W axis direction), the two outermost boundary lines being opposite to each other in the width direction (W axis direction) of the ceramic body 110 shown in the above cross-sectional image. On the other hand, the width of the ceramic body 110 may refer to the arithmetic mean of the lengths of at least two of a plurality of line segments connecting two outermost boundary lines and parallel to the width direction (W-axis direction), wherein the two outermost boundary lines are opposite to each other in the width direction (W-axis direction) of the ceramic body 110 shown in the above cross-sectional image.

[0053] The ceramic body 110 may include a plurality of dielectric layers stacked in a thickness direction (T-axis direction). The boundaries between the dielectric layers may be difficult to identify. For example, it is difficult to identify the boundaries between the dielectric layers 140 without using a scanning electron microscope (SEM), and the plurality of dielectric layers 140 may appear to be an integral structure.

[0054] The first internal electrodes 150 and the second internal electrodes 160 may be alternately stacked with the dielectric layer 140 interposed therebetween. Such a stacking structure may be repeated within the ceramic body 110, and the internal electrode closest to the fifth surface S5 of the ceramic body 110 may be the first internal electrode 150 or the second internal electrode 160. The internal electrode closest to the sixth surface S6 of the ceramic body 110 may be the first internal electrode 150 or the second internal electrode 160.

[0055] The first and second internal electrodes 150 and 160 have different polarities and may be electrically insulated from each other by the dielectric layer 140 disposed therebetween.

[0056] The first internal electrode 150 and the second internal electrode 160 may be arranged to be offset from each other in the length direction (L-axis direction) with the dielectric layer 140 interposed therebetween. One end of the first internal electrode 150 may be exposed from the first surface S1 of the ceramic body 110, and one end of the second internal electrode 160 may be exposed from the second surface S2 of the ceramic body 110. The end of the first internal electrode 150 exposed from the first surface S1 of the ceramic body 110 may be connected to the first external electrode 120. The end of the second internal electrode 160 exposed from the second surface S2 of the ceramic body 110 may be connected to the second external electrode 130.

[0057] The first and second internal electrodes 150 and 160 may be formed by printing a conductive paste including a conductive metal on the surface of the dielectric layer 140. For example, the internal electrodes may be formed by printing a conductive paste including nickel (Ni) or a nickel (Ni) alloy on the surface of the dielectric layer using a screen printing method or a gravure printing method. However, the present embodiment is not limited thereto.

[0058] For example, average thicknesses of the first and second internal electrodes 150 and 160 may be approximately 0.1 μm or more and 2 μm or less, respectively.

[0059] According to the above configuration, when a voltage is applied to the first external electrode 120 and the second external electrode 130, charges are accumulated between the first internal electrode 150 and the second internal electrode 160 facing each other. That is, capacitance may be obtained between the first internal electrode 150 electrically connected to the first external electrode 120 and the second internal electrode 160 electrically connected to the second external electrode 130. The capacitance of the multilayer ceramic capacitor 1000 is proportional to an overlapping area in which the first internal electrode 150 and the second internal electrode 160 overlap each other in the thickness direction (T-axis direction).

[0060] In other words, the multilayer ceramic capacitor 1000 may include an active region and an edge region. The active region may refer to a region where the first internal electrode 150 and the second internal electrode 160 overlap each other in the thickness direction (T-axis direction), and the edge region may refer to a region between the active region and the first surface S1 of the ceramic body 110 and a region between the active region and the second surface S2 of the ceramic body 110.

[0061] The multilayer ceramic capacitor 1000 is classified based on its length and width. Therefore, even in a multilayer ceramic capacitor having the same length or the same width, the size of the ceramic body may vary according to the thickness of the external electrode. In other words, in the case where the size of the multilayer ceramic capacitor is the same, the multilayer ceramic capacitor having a thinner external electrode may have a larger ceramic body than the multilayer ceramic capacitor having a thicker external electrode. A larger ceramic body means that the above-mentioned effective area is larger, which may further mean that the capacitance is larger. Therefore, as the external electrodes of the multilayer ceramic capacitor become thinner, the capacitance may become larger. In the present embodiment, by forming the external electrodes of the multilayer ceramic capacitor with a plating layer, the thickness of the external electrode may be made thinner, and a corresponding advantageous effect may be obtained. This will be described in more detail below.

[0062] The first cover layer 143 and the second cover layer 145 may be disposed outside the active region in a thickness direction (T-axis direction).

[0063] The first cover layer 143 is disposed between the fifth surface S5 of the ceramic body 110 and the internal electrode closest to the fifth surface S5. The second cover layer 145 is disposed between the sixth surface S6 of the ceramic body 110 and the internal electrode closest to the sixth surface S6.

[0064] That is, the first cover layer 143 is disposed on the upper portion of the uppermost inner electrode in the ceramic body 110, and the second cover layer 145 may be disposed on the lower portion of the lowermost inner electrode in the ceramic body 110. The first cover layer 143 and the second cover layer 145 may have the same composition or different compositions as the dielectric layer 140. The first cover layer 143 and the second cover layer 145 may be formed by stacking one or more dielectric layers on the outer surface of the uppermost inner electrode and the outer surface of the lowermost inner electrode, respectively.

[0065] The first and second capping layers 143 and 145 may serve to prevent the first and second internal electrodes 150 and 160 from being damaged by physical stress or chemical stress.

[0066] The dielectric layer 140 may include a ceramic material having a high dielectric constant. For example, the ceramic material may include a dielectric ceramic material containing components such as BaTiO3, CaTiO3, SrTiO3, or CaZrO3. In addition, the dielectric layer 140 may further include auxiliary components such as manganese (Mn) compounds, iron (Fe) compounds, chromium (Cr) compounds, cobalt (Co) compounds, and nickel (Ni) compounds. For example, the dielectric layer may include (Ba 1-x Ca x )TiO3 (0 < x < 1), Ba(Ti 1-y Ca y )O3 (0 < y < 1), (Ba 1-x Ca x )(Ti 1-y Zr y )O3 (0 < x < 1, 0 < y < 1), Ba(Ti 1-y Zr y )O3 (0 < y < 1), etc., but this embodiment is not limited thereto.

[0067] In addition, the dielectric layer 140 may include one or more of a ceramic additive, an organic solvent, a plasticizer, a coupling agent, and a dispersant. The ceramic additive may be, for example, a transition metal oxide or carbide, a rare earth element, magnesium (Mg), aluminum (Al), etc.

[0068] For example, the average thickness of the dielectric layer 140 may be from 0.1 μm to 10 μm, but this embodiment is not limited thereto.

[0069] The first external electrode 120 and the second external electrode 130 are provided outside the ceramic body 110. The thicknesses of both the first external electrode 120 and the second external electrode 130 are greater than 0 μm and less than or equal to 1 μm.

[0070] The first external electrode 120 is provided on the first surface S1 of the ceramic body 110 and may extend to the third surface S3, the fourth surface S4, the fifth surface S5, and / or the sixth surface S6. The second external electrode 130 is provided on the second surface S2 of the ceramic body 110 and may extend to the third surface S3, the fourth surface S4, the fifth surface S5, and / or the sixth surface S6. In other embodiments, the first external electrode 120 and the second external electrode 130 may each extend to at least one of the fifth surface S5 and the sixth surface S6.

[0071] The first external electrode 120 includes a first end portion 121, a first belt portion 123, and a first edge portion 125.

[0072] The first end portion 121 is a portion covering the first surface S1 of the ceramic body 110 and electrically connected to exposed ends of the plurality of first internal electrodes 150 .

[0073] The first band portion 123 extends from the first end portion 121 and covers at least a portion of at least one of the third, fourth, fifth, and sixth surfaces S3, S4, S5, and S6 of the ceramic body 110. The first band portion 123 may allow the first external electrode 120 to adhere to the ceramic body 110 more firmly.

[0074] The first edge portion 125 may be a portion connecting the first end portion 121 and the first belt portion 123 .

[0075] The second external electrode 130 includes a second end portion 131 , a second band portion 133 , and a second edge portion 135 .

[0076] The second end portion 131 is a portion covering the second surface S2 of the ceramic body 110 and electrically connected to exposed ends of the plurality of second internal electrodes 160 .

[0077] The second band portion 133 extends from the second end portion 131 and covers at least a portion of at least one of the third, fourth, fifth, and sixth surfaces S3, S4, S5, and S6 of the ceramic body 110. The second band portion 133 may allow the second external electrode 130 to adhere to the ceramic body 110 more firmly.

[0078] The second edge portion 135 may be a portion connecting the second end portion 131 and the second belt portion 133 .

[0079] Based on an optical microscope image or a scanning electron microscope (SEM) image of a cross section in the length direction (L-axis direction) and the thickness direction (T-axis direction) taken at the central portion in the width direction (W-axis direction) of the ceramic body 110, the first end portion 121 and the second end portion 131 may have a shape substantially parallel to the thickness direction (T-axis direction), the first band portion 123 and the second band portion 133 may have a shape substantially parallel to the length direction (L-axis direction), and the first edge portion 125 and the second edge portion 135 may have a curved shape. The curved shape may be a curved shape having a tangent line whose slope changes from a direction parallel to the thickness direction (T-axis direction) to a direction parallel to the length direction (L-axis direction) (or vice versa).

[0080] In addition, the first external electrode 120 may include a first plating layer 127 , and the second external electrode 130 may include a second plating layer 137 , and this will be described in detail below.

[0081] Figure 4 It is laser irradiation Figure 1 A perspective view of a ceramic body of a multilayer ceramic capacitor.

[0082] Reference Figure 4 The ceramic body 110 may include a first laser irradiation region 200, a second laser irradiation region 300, and a laser non-irradiation region 400, and the first laser irradiation region 200 and the second laser irradiation region 300 are irradiated with laser. The irradiated laser here may be a femtosecond laser, but the present embodiment is not limited thereto.

[0083] After the laser irradiation is completed, a plating process may be performed on the first laser irradiation region 200 to form a first plating layer 127, and a plating process may be performed on the second laser irradiation region 300 to form a second plating layer 137. That is, the first laser irradiation region 200 is a region in which the first external electrode 120 is to be formed, and the second laser irradiation region 300 is a region in which the second external electrode 130 is to be formed.

[0084] For example, the first laser irradiation region 200 may include the first surface S1 and a portion of the third surface S3, a portion of the fourth surface S4, a portion of the fifth surface S5, and a portion of the sixth surface S6 of the ceramic body 110, and the second laser irradiation region 300 may include the second surface S2 and a portion of the third surface S3, a portion of the fourth surface S4, a portion of the fifth surface S5, and a portion of the sixth surface S6 of the ceramic body 110. However, the present embodiment is not limited thereto, and the range of the laser irradiation region may vary according to the shape of the external electrode to be formed.

[0085] As an example, the ceramic body 110 may include laser irradiation regions 200 and 300 formed by laser irradiation and a laser non-irradiation region 400 that is not irradiated by the laser, and the laser irradiation regions 200 and 300 extend from a portion of the surface of the ceramic body 110 that contacts the first plating layer 127 and the second plating layer 137 to a predetermined depth toward the inside of the ceramic body 110. The laser non-irradiation region 400 is a portion of the ceramic body 110 other than the first laser irradiation region 200 and the second laser irradiation region 300. The laser non-irradiation region 400 includes not only the surface of the ceramic body 110 but also an internal region, that is, a lower region of the first laser irradiation region 200 and the second laser irradiation region 300.

[0086] The first laser irradiation region 200 and the second laser irradiation region 300 may have a resistance smaller than that of the rest of the ceramic body 110. That is, the surface resistance of the first laser irradiation region 200 may be smaller than that of the laser non-irradiation region 400, and the surface resistance of the second laser irradiation region 300 may be smaller than that of the laser non-irradiation region 400. For example, the ratio of the surface resistance of the first laser irradiation region 200 (or the second laser irradiation region 300) to the surface resistance of the laser non-irradiation region 400 may be 1 / 10. 4or greater and less than 1.

[0087] Since the first laser irradiation region 200 and the second laser irradiation region 300 have relatively small resistance, when a plated layer is formed by electroplating, a reduction reaction of the metal may occur more easily in the first laser irradiation region 200 and the second laser irradiation region 300 than in the laser non-irradiation region 400. Therefore, the plated metal may be deposited faster and more easily from the first laser irradiation region 200 and the second laser irradiation region 300.

[0088] Figure 5 yes Figure 2 Magnified view of area A.

[0089] Reference Figure 5 and Figure 2 The first external electrode 120 includes a first plating layer 127 , and the first plating layer 127 may be disposed in the first laser irradiation region 200 of the ceramic body 110 .

[0090] The first plating layer 127 may be formed by directly plating a conductive metal on the first laser irradiation region 200. Here, the conductive metal may include at least one of nickel (Ni), copper (Cu), tin (Sn), palladium (Pd), platinum (Pt), gold (Au), silver (Ag), tungsten (W), titanium (Ti), lead (Pb), and alloys thereof, but the present embodiment is not limited thereto.

[0091] The second plating layer 137 is identical in structure and composition to the first plating layer 127 except for the position, and thus a redundant description thereof will be omitted.

[0092] Since the second plating layer 137 has the same structure and composition as the first plating layer 127 except for its position, the following description will mainly focus on the first laser irradiation region 200 .

[0093] The first laser irradiation region 200 may include an outer layer portion 210 and an inner layer portion 220. The outer layer portion 210 is a portion that forms the outer surface of the first laser irradiation region 200 and contacts the first plating layer 127. Microcracks 213 exist in the outer layer portion 210. The microcracks 213 may be generated by melting the outer layer portion 210 by laser irradiation and rapidly cooling the outer layer portion 210. For example, the microcracks 213 may have a depth of greater than or equal to 10 nm and less than or equal to 1000 nm. If the depth of the microcracks 213 is less than 10 nm, the adhesion of the plating layer may be weak, and if it exceeds 1000 nm, there is a risk of affecting the inner electrode of the multilayer ceramic capacitor.

[0094] The presence and depth of the microcracks 213 are observed and measured based on field emission (FE) type scanning electron microscope (SEM) (accelerating voltage: 5 kV) images of cross sections in the length direction (L axis direction) and the thickness direction (T axis direction) taken at the central portion in the width direction (W axis direction) of the multilayer ceramic capacitor 1000. The depth of the microcracks 213 can be measured by a standard method that is obvious and understandable to those of ordinary skill in the art.

[0095] The microcracks 213 of the outer layer portion 210 are filled with the metal forming the first plating layer 127. In other words, the plated metal may grow from the inside of the microcracks 213 to form the first plating layer 127. For example, the first external electrode 120 may include the first plating layer 127 that contacts the surface of the ceramic body 110 and is connected to the inner electrode, and the microcracks 213 exist inward from the portion of the surface of the ceramic body 110 that contacts the first plating layer 127, and the microcracks 213 may be filled with the metal forming the first plating layer 127. In this case, the contact area between the plating layer and the outer layer portion is wider than in the case where the microcracks do not exist, and thus the plating layer may be more firmly bonded to the ceramic body.

[0096] The inner layer portion 220 is a portion that forms the inner surface of the first laser irradiation region 200 and contacts the laser non-irradiation region 400. Microcracks do not exist in the inner layer portion 220. For example, the inner surface of the first laser irradiation region 200 may be an interface between the first laser irradiation region 200 and the laser non-irradiation region 400.

[0097] In addition, the first laser irradiation region 200 may include an amorphous structure. In contrast, the remaining portion of the ceramic body 110 may have a lattice structure. In other words, as a result of laser irradiation of the surface of the ceramic body 110, the lattice structure of the corresponding region (e.g., the region corresponding to the laser irradiation regions 200 and 300) may be reformed into an amorphous structure. In a lattice structure, in order to maintain electrostatic balance and stoichiometry, the proportion of a specific element within the structure cannot be increased beyond a certain level, while the amorphous structure in the laser irradiation region has no such limitation, so the proportion of a specific element within the amorphous structure can be increased. In other words, when the laser is irradiated to the laser irradiation region, the microstructure of the region changes from a lattice structure to an amorphous structure, generating excess electrons or holes that did not exist before and reducing the band gap energy within the structure (similar to the effect of doping a semiconductor). Therefore, when the laser irradiation region is irradiated with laser, the energy barrier for metal precipitation (reduction reaction) during plating is reduced, and the structure can be changed to a structure that is easier to plate. As an example, a portion of the surface of the ceramic body 110 that contacts the plating layer (127 or 137) includes an amorphous structure, and a ratio of a barium (Ba) content to a titanium (Ti) content (Ba / Ti) in the amorphous structure may be smaller than a ratio of a barium (Ba) content to a titanium (Ti) content (Ba / Ti) in a remaining area of ​​the surface of the ceramic body 110 excluding the amorphous structure.

[0098] The ceramic body 110 includes barium (Ba) and titanium (Ti), and a ratio (Ba / Ti) of a barium (Ba) content (unit: at%) to a titanium (Ti) content (unit: at%) in the first laser irradiation region 200 may be smaller than a ratio (Ba / Ti) of a barium (Ba) content to a titanium (Ti) content in the laser non-irradiation region 400. That is, the first laser irradiation region 200 may be a region relatively rich in titanium (Ti) compared to the laser non-irradiation region 400. Since titanium is relatively abundant in the laser irradiation region, a band gap in the region may be reduced or surface resistance of the region may be reduced.

[0099] For example, the ratio (Ba / Ti) of the barium (Ba) content (unit: at%) to the titanium (Ti) content (unit: at%) in the first laser irradiation area 200 is greater than or equal to 0.01 and less than or equal to 0.02, but the ratio (Ba / Ti) of the barium (Ba) content to the titanium (Ti) content in the laser non-irradiation area 400 may be greater than or equal to 0.9 and less than or equal to 1.1.

[0100] Figure 6 yes Figure 4 A top plan view of the laser irradiated area of ​​the ceramic body of the multilayer ceramic capacitor, Figure 7 yes Figure 6 is an enlarged view of region B in FIG. 1 , and Figure 8 It is shown Figure 7Figure 2. Measurement results of the shape of the bent portion.

[0101] Reference Figure 6 , Figure 7 and Figure 8 , the first laser irradiation region 200 may include a curved portion 230 , and the curved portion 230 may include an irregular pattern including repeated valleys 233 and ridges 235 .

[0102] The profiles of the valleys 233 and ridges 235 of the curved portion 230 may be measured using a focus variation mode or a confocal laser mode of a three-dimensional profiler (3D profiler). For example, an average profile of more than 200 line segments connecting the valleys or ridges may be measured. The average period of the valleys or ridges may be greater than or equal to 0.1 μm and less than or equal to 8 μm, and the average amplitude may be greater than or equal to 0.01 μm and less than or equal to 1 μm. For example, referring to Figure 8 The average period may refer to the average value of the distances between the maximum amplitudes of adjacent valleys, or may refer to the average value of the distances between the maximum amplitudes of adjacent ridges (see Figure 8 ).

[0103] The above-described micro cracks 213 may exist in the ridges 235 , and the resistance in the ridges 235 may be smaller than the resistance in the valleys 233 .

[0104] The bent portion 230 exists in the first laser irradiation region 200, and thus the moisture permeation path can be extended, thereby improving the moisture-proof reliability of the multilayer ceramic capacitor 1000. In addition, since the specific surface areas of the first plating layer 127 of the first external electrode 120 and the first laser irradiation region 200 are increased due to the presence of the bent portion 230, the adhesion strength of the first plating layer 127 can be improved.

[0105] As in the present embodiment, after laser irradiation, forming a plating layer on the surface of the ceramic body can produce a thin external electrode. For example, the external electrode can have a thickness greater than 0 μm and less than or equal to 1 μm. When the external electrode is thin, the portion that contributes to the formation of capacitance can be increased, thereby improving the performance of the multilayer ceramic capacitor.

[0106] Furthermore, in the present embodiment, micro cracks are formed on the surface of the ceramic body irradiated with the laser, and the micro cracks are filled with the plating layer, so the plating layer can be firmly bonded to the surface of the ceramic body.

[0107] However, unlike the present embodiment, when a plating layer is formed on a base electrode formed by immersing a ceramic body in a conductive paste and absorbing it, the sum of the thickness of the base electrode and the plating layer may be about 10 μm or more, which is greater than the thickness of the external electrode according to the present embodiment (greater than 0 μm and less than or equal to 1 μm). Compared with the present embodiment, when the external electrode according to the prior art is relatively thick and the volume occupied by the external electrode is large, the size of the portion that contributes to the formation of capacitance is relatively reduced, thereby deteriorating the performance of the multilayer ceramic capacitor.

[0108] Furthermore, unlike the present embodiment, when a metal film is formed on the surface of a ceramic body without laser irradiation according to the prior art and then a plating layer is formed using the metal film as a seed layer, the seed layer may peel off during the plating layer forming process, resulting in poor plating.

[0109] Hereinafter, detailed embodiments of the present disclosure will be disclosed. However, the embodiments described below are only for illustrating or describing the present disclosure in detail and should not limit the scope of the present invention.

[0110] [Production Example: Manufacture of Multilayer Ceramic Capacitor]

[0111] (Example)

[0112] A paste including barium titanate (BaTiO 3 ) powder is coated on a carrier film and dried to prepare a plurality of dielectric green sheets.

[0113] A conductive paste containing nickel (Ni) is applied on the dielectric green sheet using a screen printing method to form a conductive paste layer.

[0114] The dielectric green sheet laminate is manufactured by stacking a plurality of dielectric green sheets while ensuring that at least a portion of the conductive paste layers overlap each other.

[0115] The dielectric green sheet laminate was cut into individual chips, held at 350° C. for 66 hours in an air atmosphere to remove the binder, and fired at 1165° C. to produce a ceramic body.

[0116] Next, a femtosecond laser is irradiated to the laser irradiation area of ​​the ceramic body to form an irregular pattern having a period of 0.1 μm or more and 8 μm or less and an amplitude of 0.01 μm or more and 1 μm or less.

[0117] Next, a copper (Cu) plating layer is formed in the laser irradiated region to manufacture a multilayer ceramic capacitor.

[0118] (Comparison example)

[0119] A paste including barium titanate (BaTiO 3 ) powder is coated on a carrier film and dried to prepare a plurality of dielectric green sheets.

[0120] A conductive paste containing nickel (Ni) is applied on the dielectric green sheet using a screen printing method to form a conductive paste layer.

[0121] The dielectric green sheet laminate is manufactured by stacking a plurality of dielectric green sheets while ensuring that at least a portion of the conductive paste layers overlap each other.

[0122] The dielectric green sheet laminate was cut into individual chips, held at 350° C. for 66 hours in an air atmosphere to remove the binder, and fired at 1165° C. to produce a ceramic body.

[0123] Next, the ceramic body was dipped into a slurry including glass frit and copper (Cu) and sucked dry, and then thermally dried and sintered at 820° C. for 60 minutes to form a base electrode.

[0124] Then, a nickel (Ni) layer and / or a tin (Sn) layer is plated on the base electrode to manufacture a multilayer ceramic capacitor.

[0125] [Experimental example: Performance of multilayer ceramic capacitors]

[0126] The thickness, surface resistance, and ratio of barium (Ba) content to titanium (Ti) content (Ba / Ti) of the external electrodes of the multilayer ceramic capacitors manufactured in the example and the comparative example were measured, and it was determined whether an amorphous structure existed.

[0127] 1) Method for measuring the thickness of the outer electrode

[0128] Each of the five manufactured multilayer ceramic capacitors was mounted in an epoxy resin mold, and the surfaces in the L-axis direction and the T-axis direction were polished to a depth of about 1 / 2 along the W-axis direction and finished with diamond paste to prepare a cross-sectional sample.

[0129] In the prepared cross-sectional sample, the position of the visible first or second external electrode at about 70 μm in a direction from the interface of the first or second external electrode and the ceramic body to the plating layer was measured using a metallographic microscope in bright field mode and 500 times magnification.

[0130] 2) Method for measuring surface resistance

[0131] The atomic force microscope (AFM, such as Dimension ICON) (test conditions are as follows, AFM probe: DDESP-V2; material: coated conductive diamond; scanning area: 20×20 μm 2 ; Scanning speed: <0.3 Hz Line direction: retrace; Microscope mode: SSRM mode) Surface resistance was measured. Here, the bias voltage was limited to 10 V and the contact force was limited to 10 μN.

[0132] 3) Methods for identifying amorphous structures

[0133] Each of the five manufactured multilayer ceramic capacitors was mounted in an epoxy resin mold, and the surfaces in the L-axis direction and the T-axis direction were polished to a depth of about 1 / 2 along the W-axis direction and finished with diamond paste to prepare a cross-sectional sample.

[0134] In the prepared cross-sectional sample, a field emission (FE)-transmission electron microscope (TEM) is used to measure the position of the visible first external electrode or the second external electrode at approximately 70 μm in the direction from the interface of the first external electrode or the second external electrode and the ceramic body to the plating layer, and the diffraction patterns in the laser irradiated area and the laser non-irradiated area are compared and observed to determine whether an amorphous structure exists.

[0135] For example, the STEM image was observed with a JEOL-ARM200F at 200 kV using a condenser lens aperture, and the diffraction pattern was observed in the BF mode at 200 kV using a condenser lens aperture of 100 μm.

[0136] 4) Ba / Ti measurement method

[0137] Each of the five manufactured multilayer ceramic capacitors was mounted in an epoxy resin mold, and the surfaces in the L-axis direction and the T-axis direction were polished to a depth of about 1 / 2 along the W-axis direction and finished with diamond paste to prepare a cross-sectional sample.

[0138] In the prepared cross-sectional sample, the position of the visible first external electrode or the second external electrode at approximately 70 μm in the direction from the interface of the first external electrode or the second external electrode with the ceramic body to the plating layer was measured using a field emission (FE)-transmission electron microscope (TEM), and energy dispersive spectroscopy (EDS) was performed to calculate the ratio (Ba / Ti) of the barium (Ba) content (unit: at %) to the titanium (Ti) content (unit: at %).

[0139] For example, STEM images were observed using a JEOL-ARM200F at 200 kV using a condenser lens aperture, and energy dispersive spectroscopy was performed using Oxford's X-max.

[0140] The results of measuring the thickness and surface resistance of the external electrodes of the multilayer ceramic capacitors manufactured in the example and the comparative example and determining whether the amorphous structure existed are shown in Table 1.

[0141] (Table 1)

[0142]

[0143] Referring to Table 1, it can be confirmed that the thickness of the external electrode of the multilayer ceramic capacitor manufactured in the example is greater than 0 μm and less than or equal to 1 μm. On the other hand, it can be confirmed that the thickness of the external electrode of the multilayer ceramic capacitor manufactured in the comparative example is greater than or equal to 10 μm and less than or equal to 40 μm. In this way, the thickness of the external electrode of the multilayer ceramic capacitor manufactured in the example is less than 10 μm, which is less than the thickness of the external electrode of the multilayer ceramic capacitor manufactured in the comparative example.

[0144] Therefore, when the size of the multilayer ceramic capacitor is the same, the external electrode according to the present embodiment can be made thinner, and the volume of the portion that contributes to forming the capacitance (such as the inner electrode and the dielectric layer) can be made larger. That is, according to the present embodiment, by reducing the volume of the external electrode, the portion that contributes to forming the capacitance can be made larger.

[0145] Furthermore, it was confirmed that the surface resistance of the laser irradiated region of the multilayer ceramic capacitor manufactured in the example was smaller than the surface resistance of the laser non-irradiated region.

[0146] Furthermore, it was confirmed that an amorphous structure existed in the laser irradiated region of the multilayer ceramic capacitor manufactured in the example, whereas an amorphous structure did not exist in the laser non-irradiated region.

[0147] Figures 9 to 12 FE-TEM analysis images and EDS analysis results according to the embodiment are shown, and Table 2 shows the results of measuring Ba / Ti in a selected area of ​​each figure.

[0148] (Table 2)

[0149]

[0150]

[0151] Reference Figures 9 to 12 As shown in Table 2, in the multilayer ceramic capacitor manufactured in the example, the ratio of the barium (Ba) content to the titanium (Ti) content (Ba / Ti) in the laser irradiated area is less than the ratio of the barium (Ba) content to the titanium (Ti) content (Ba / Ti) in the laser non-irradiated area. In other words, it can be confirmed that the laser irradiated area is relatively rich in titanium (Ti).

[0152] While the present disclosure has been described in connection with what are presently considered to be practical embodiments, it should be understood that the present disclosure is not limited to the disclosed embodiments, but is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A multilayer ceramic capacitor comprising: Ceramic body; An inner electrode, disposed inside the ceramic body; as well as an outer electrode including a plating layer contacting with a surface of the ceramic body and connected to the inner electrode, wherein microcracks exist from a portion of the surface of the ceramic body in contact with the plating layer toward the inside, and the microcracks are filled with a metal forming the plating layer, and The portion of the surface of the ceramic body in contact with the plating layer includes an amorphous structure.

2. The multilayer ceramic capacitor according to claim 1, wherein: The portion of the surface of the ceramic body in contact with the plating layer includes a bent portion.

3. The multilayer ceramic capacitor of claim 2, wherein: The curved portion comprises an irregular pattern comprising repeating valleys and ridges, and An average period of the valleys or the ridges is greater than or equal to 0.1 μm and less than or equal to 8 μm, and an average amplitude of the valleys or the ridges is greater than or equal to 0.01 μm and less than or equal to 1 μm.

4. The multilayer ceramic capacitor of claim 2, wherein: The curved portion includes valleys and ridges, and The microcracks are present in the ridges.

5. The multilayer ceramic capacitor of claim 1, wherein: The depth of the microcracks is greater than or equal to 10 nm and less than or equal to 1000 nm.

6. The multilayer ceramic capacitor of claim 1, wherein: The ceramic body includes barium and titanium, and A ratio of a barium content to a titanium content in the amorphous structure is smaller than a ratio of a barium content to a titanium content in a remaining region of the surface of the ceramic body excluding the amorphous structure.

7. The multilayer ceramic capacitor of claim 1, wherein: The portion of the surface of the ceramic body that is in contact with the plating layer has a lower resistance than a portion of the surface of the ceramic body that is not in contact with the plating layer.

8. The multilayer ceramic capacitor of claim 7, wherein: The ratio of the resistance of the portion of the surface of the ceramic body that contacts the plating layer to the resistance of the portion of the surface of the ceramic body that does not contact the plating layer is greater than or equal to 1 / 10. 4 And less than 1.

9. The multilayer ceramic capacitor of claim 2, wherein: The curved portion includes valleys and ridges, and The resistance of the ridges is smaller than the resistance of the valleys.

10. The multilayer ceramic capacitor of claim 1, wherein: The thickness of the coating is greater than 0 μm and less than or equal to 1 μm.

11. The multilayer ceramic capacitor of claim 1, wherein: The ceramic body includes a laser irradiated area formed by laser irradiation and a laser non-irradiated area not irradiated by laser, wherein the laser irradiated area extends from the portion of the surface of the ceramic body in contact with the plating layer toward the inside of the ceramic body by a predetermined depth.

12. The multilayer ceramic capacitor of claim 11, wherein: The resistance of the laser irradiated region is lower than the resistance of the laser non-irradiated region.

13. The multilayer ceramic capacitor of claim 11, wherein: The ceramic body includes barium and titanium, and A ratio of a barium content to a titanium content in the amorphous structure located in the laser irradiated region is smaller than a ratio of a barium content to a titanium content in the laser non-irradiated region.

14. The multilayer ceramic capacitor of claim 11, wherein: The laser irradiation area includes an outer layer part and an inner layer part, The outer layer portion is a portion that forms the outer surface of the laser irradiation area and contacts the plating layer, The microcracks are present in the outer layer portion, The inner layer portion is a portion that forms the inner surface of the laser irradiated region and is in contact with the laser non-irradiated region, and No microcracks exist in the inner layer portion.

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