Multilayer ceramic capacitor

Abstract

The present disclosure provides a multilayer ceramic capacitor including: a ceramic body including stacked dielectric layers and inner electrodes; and an external electrode disposed outside the ceramic body, in which at least one of the internal electrodes includes a protrusion protruding from a surface of the ceramic body and in contact with an interdiffusion portion, and the interdiffusion portion includes an alloy of a material of the inner electrode and a material of the outer electrode or an intermetallic compound (IMC) of the material of the inner electrode and the material of the outer electrode.

Description

Technical Field

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

[0002] Electronic components using ceramic materials include 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 small size, high capacity, and ease of mounting.

[0003] For example, multilayer ceramic capacitors can be used as chip capacitors mounted on substrates of various electronic products (such as, imaging devices (such as liquid crystal displays (LCDs), plasma display panels (PDPs), organic light emitting diode (OLED) displays), computers, personal portable devices, and smart phones) and used for charging or discharging.

[0004] The 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. When the material of the outer electrode and the material of the inner electrode are different from each other, radiation cracks may occur. Summary of the invention

[0005] An aspect of the present disclosure is to provide a multilayer ceramic capacitor that can prevent the occurrence of radiation cracks.

[0006] The present disclosure provides a multilayer ceramic capacitor, comprising: a ceramic body including stacked dielectric layers and inner electrodes; and outer electrodes arranged outside the ceramic body, wherein at least one of the inner electrodes includes a protrusion protruding from a first surface of the ceramic body and contacting an interdiffusion portion, and the interdiffusion portion includes an alloy of a material of the inner electrode and a material of the outer electrode or an intermetallic compound (IMC) of a material of the inner electrode and a material of the outer electrode.

[0007] The interdiffusion portion may surround the protrusion.

[0008] The interdiffusion portion may be disposed on the first surface of the ceramic body.

[0009] A material of the at least one of the internal electrodes may include nickel (Ni), copper (Cu), palladium (Pd), silver (Ag), iron (Fe), or an alloy thereof.

[0010] The material of the external electrode may include nickel (Ni), copper (Cu), palladium (Pd), gold (Au), silver (Ag), cobalt (Co), chromium (Cr), iron (Fe), tin (Sn), platinum (Pt), indium (In), iridium (Ir), rhodium (Rh), zinc (Zn) or an alloy thereof.

[0011] A length of the interdiffusion portion in the length direction of the ceramic body may be greater than a length of the protrusion of the at least one of the internal electrodes in the length direction.

[0012] The length of the interdiffusion portion in the longitudinal direction may be greater than or equal to 0.5 μm and less than or equal to 2 μm.

[0013] The multilayer ceramic capacitor may further include a plating layer covering the external electrodes.

[0014] The plating layer may include: a first layer covering the external electrode; a second layer covering the first layer; and a third layer covering the second layer.

[0015] The first layer may include nickel (Ni), the second layer may include copper (Cu), and the third layer may include tin (Sn).

[0016] Each of the internal electrodes may include a protrusion protruding from the first surface of the ceramic body, and the interdiffusion portion may include a plurality of interdiffusion portions respectively surrounding the protrusions.

[0017] The plurality of interdiffusion portions may be spaced apart from one another.

[0018] The external electrode may include an end portion, a band portion, and an edge portion, wherein the end portion covers a portion of the first surface of the ceramic body, the band portion extends from the end portion to cover at least a portion of four surfaces of the ceramic body connected to the first surface, and the edge portion connects the end portion and the band portion.

[0019] According to the multilayer ceramic capacitor of the present disclosure, an alloy or an intermetallic compound may be formed between the protrusion of the inner electrode protruding outward from the ceramic body and the outer electrode to prevent the occurrence of radiation cracks. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A perspective view schematically illustrates a multilayer ceramic capacitor according to an embodiment.

[0021] Figure 2 Shown along Figure 1 A cross-sectional view taken along line II-II'. DETAILED DESCRIPTION

[0022] The present disclosure will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the present disclosure are shown. The drawings and description are to be considered illustrative rather than restrictive in nature. Throughout the specification, similar reference numerals represent similar elements. In addition, some constituent elements are enlarged, omitted or briefly shown in the drawings, and the sizes of the individual constituent elements do not reflect the actual sizes.

[0023] The accompanying drawings are provided only to make the embodiments disclosed in this specification easier to understand and shall not be interpreted as limiting the spirit disclosed in this specification. It will be understood that the present disclosure includes all modifications, equivalents, and alternatives without departing from the scope and spirit of the claims of the present disclosure.

[0024] Terms including ordinal numbers such as first, second, etc. will only be used to describe various constituent elements and will not be interpreted as limiting these constituent elements. These terms are only used to distinguish one constituent element from other constituent elements.

[0025] It will be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" or "over" another element, the element may be directly on the other element, or there may be intervening elements. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements. Furthermore, in the specification, the words "on" or "over" mean disposed on or below an object, and do not necessarily mean disposed on the upper side of an object based on the direction of gravity.

[0026] Throughout the specification, it should be understood that the terms "include", "comprising", "having" or "configured" indicate the presence of the features, quantities, steps, operations, parts or combinations thereof described in the specification, but do not exclude the possibility of the presence or addition of one or more other features, quantities, steps, operations, parts or combinations thereof. Unless explicitly described to the contrary, the word "include" and variations such as "including" or "having" will be understood to imply the inclusion of the stated elements but not the exclusion of any other elements.

[0027] Furthermore, throughout the specification, the phrase “in a plan view” or “on a plane” means observing an object from the top, and the phrase “in a cross-sectional view” or “on a cross section” means observing a cross section formed by vertically cutting an object from the side.

[0028] In addition, throughout the specification, "connection" means not only a case where two or more elements are directly connected, but also a case where two or more elements are indirectly connected through other elements and a case where two or more elements are physically and / or electrically connected. In addition, "connection" also includes a case where two or more elements are substantially integrated and connected to each other although they are represented by different names according to positions or functions.

[0029] Figure 1 A perspective view schematically shows a multilayer ceramic capacitor according to an embodiment, and Figure 2 Shown along Figure 1 A cross-sectional view taken along line II-II'.

[0030] Reference Figure 1 and Figure 2 , 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 .

[0031] First, directions are defined in order to clearly describe the present embodiment, and an L axis, a W axis, and a T axis shown in the drawings indicate axes representing a length direction, a width direction, and a thickness direction of the multilayer ceramic capacitor 1000 , respectively.

[0032] The thickness direction (T-axis direction) may be a direction perpendicular to the wide surface (main surface) of the sheet member. For example, the thickness direction (T-axis direction) may be used as the same concept as the direction in which the dielectric layer 140 is stacked.

[0033] The length direction (L-axis direction) is a direction parallel to the wide surface (main surface) of the sheet component and may be a direction intersecting (or perpendicular to) the thickness direction (T-axis direction). For example, the length direction (L-axis direction) may be a direction in which the first external electrode 120 and the second external electrode 130 are opposite to each other.

[0034] The width direction (W-axis direction) is a direction parallel to the wide surface (main surface) of the sheet component and may be a direction intersecting (or perpendicular to) both the thickness direction (T-axis direction) and the length direction (L-axis direction).

[0035] 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 have a substantially hexahedral shape, although not a completely hexahedral shape. For example, the ceramic body 110 may have a substantially rectangular hexahedral shape, but the corners or vertex portions may have a rounded shape.

[0036] In this embodiment, for the convenience of description, surfaces opposite to each other in the length direction (L-axis direction) are defined as a first surface S1 and a second surface S2, surfaces opposite to each other in the width direction (W-axis direction) and connecting the first surface S1 and the second surface S2 are defined as a third surface S3 and a fourth surface S4, and surfaces opposite to each other in the thickness direction (T-axis direction) and connecting the first surface S1 to the fourth surface S4 are defined as a fifth surface S5 and a sixth surface S6.

[0037] Therefore, the first direction relative to the first surface S1 and the second surface S2 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), or the width direction (W-axis direction) and the thickness direction (T-axis direction), respectively.

[0038] The length of the ceramic body 110 may refer to: based on an optical microscope photograph or a scanning electron microscope (SEM) photograph of a cross section taken along the length direction (L axis direction)-thickness direction (T axis direction) at the center of the width direction (W axis direction) of the ceramic body 110, the maximum value of the lengths of a plurality of line segments connecting two outermost boundary lines of the ceramic body 110 shown in the cross-sectional photograph that are opposite to each other in the length direction (L axis direction) and parallel to the length direction (L axis direction). In addition, the length of the ceramic body 110 may refer to the minimum value of the lengths of a plurality of line segments connecting two outermost boundary lines of the ceramic body 110 shown in the cross-sectional photograph that are opposite to each other in the length direction (L axis direction) and parallel to the length direction (L axis direction). 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 the plurality of line segments, the plurality of line segments connecting two outermost boundary lines of the ceramic body 110 shown in the cross-sectional photograph that are opposite to each other in the length direction (L axis direction) and parallel to the length direction (L axis direction). The length of the ceramic body 110 may be measured by standard methods that will be readily appreciated and understood by one of ordinary skill in the art.

[0039] The thickness of the ceramic body 110 may refer to: based on an optical microscope photograph or a scanning electron microscope (SEM) photograph of a cross section taken along the length direction (L axis direction)-thickness direction (T axis direction) at the center of the width direction (W axis direction) of the ceramic body 110, the maximum value of the lengths of a plurality of line segments connecting two outermost boundary lines of the ceramic body 110 shown in the cross-sectional photograph that are opposite to each other in the thickness direction (T axis direction) and parallel to the thickness direction (T axis direction). In addition, the thickness of the ceramic body 110 may refer to the minimum value of the lengths of a plurality of line segments connecting two outermost boundary lines of the ceramic body 110 shown in the cross-sectional photograph that are opposite to each other in the thickness direction (T axis direction) and parallel to the thickness direction (T axis direction). On the other hand, the thickness of the ceramic body 110 may refer to the arithmetic mean of the lengths of at least two line segments among the plurality of line segments, the plurality of line segments connecting two outermost boundary lines of the ceramic body 110 shown in the cross-sectional photograph that are opposite to each other in the thickness direction (T axis direction) and parallel to the thickness direction (T axis direction). The thickness of the ceramic body 110 may be measured by standard methods that will be readily appreciated and understood by one of ordinary skill in the art.

[0040] The width of the ceramic body 110 may refer to: based on an optical microscope photograph or a scanning electron microscope (SEM) photograph of a cross section taken along the length direction (L axis direction)-width direction (W axis direction) at the center of the thickness direction (T axis direction) of the ceramic body 110, the maximum value of the lengths of a plurality of line segments connecting two outermost boundary lines of the ceramic body 110 shown in the cross-sectional photograph that are opposite to each other in the width direction (W axis direction) and are parallel to the width direction (W axis direction). In addition, the width of the ceramic body 110 may refer to the minimum value of the lengths of a plurality of line segments connecting two outermost boundary lines of the ceramic body 110 shown in the cross-sectional photograph that are opposite to each other in the width direction (W axis direction) and are parallel to the width direction (W axis direction). On the other hand, the width of the ceramic body 110 may refer to the arithmetic mean of the lengths of at least two line segments among the plurality of line segments, the plurality of line segments connecting two outermost boundary lines of the ceramic body 110 shown in the cross-sectional photograph that are opposite to each other in the width direction (W axis direction) and are parallel to the width direction (W axis direction). The width of the ceramic body 110 may be measured by standard methods that will be readily appreciated and understood by one of ordinary skill in the art.

[0041] The ceramic body 110 may include a plurality of dielectric layers 140 stacked in a thickness direction (T-axis direction). The boundaries between the dielectric layers 140 may be unclear. For example, it is difficult to confirm the boundaries between the dielectric layers 140 without using a scanning electron microscope (SEM), and the plurality of dielectric layers 140 may be a structure that appears to be integrated.

[0042] The first internal electrodes 150 and the second internal electrodes 160 may be alternately stacked with the dielectric layer 140 interposed between the first internal electrodes 150 and the second internal electrodes 160. This 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. Similarly, 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.

[0043] 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.

[0044] The first inner electrode 150 and the second inner electrode 160 may be disposed to be offset from each other in the length direction (L-axis direction) with the dielectric layer 140 interposed therebetween. Ends of the first inner electrode 150 may be exposed from the first surface S1 of the ceramic body 110, and ends of the second inner electrode 160 may be exposed from the second surface S2 of the ceramic body 110. That is, at least one of the first inner electrodes 150 may include a first protrusion 151 protruding from the first surface S1 of the ceramic body 110, and / or at least one of the second inner electrodes 160 may include a second protrusion 161 protruding from the second surface S2 of the ceramic body 110. The first protrusion 151 of the first inner electrode 150 may be connected to the first outer electrode 120, and the second protrusion 161 of the second inner electrode 160 may be connected to the second outer electrode 130. This will be described later.

[0045] For example, the first and second internal electrodes 150 and 160 may include nickel (Ni), copper (Cu), palladium (Pd), silver (Ag), iron (Fe), or an alloy thereof.

[0046] 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 containing nickel (Ni) or a nickel (Ni) alloy on the surface of the dielectric layer using screen printing or gravure printing. However, the present embodiment is not limited thereto.

[0047] For example, the average thicknesses of the first and second internal electrodes 150 and 160 may be approximately equal to or greater than 0.1 μm and equal to or less than 2 μm, respectively.

[0048] Here, the thickness of the inner electrode 150 or 160 may refer to the average thickness of one inner electrode disposed between two dielectric layers. The average thickness of the inner electrode may be: based on a scanning electron microscope (SEM) photograph of a cross section taken along the length direction (L axis direction)-thickness direction (T axis direction) at the center of the width direction (W axis direction) of the ceramic body 110 with a magnification of 10,000 times, the arithmetic mean of the thickness measured at 30 equally spaced points in the length direction (L axis direction) of one inner electrode shown in the above cross-sectional photograph. The above 30 points may be specified in the effective area to be described later. In this way, the average thickness of the inner electrode may be further generalized by measuring the average thickness of 10 inner electrodes respectively and then obtaining the arithmetic mean of the measured values. The measurement of the average thickness is not limited to these examples, and if necessary, a person of ordinary skill may select the number of measurement points, the intervals between the measurement points, the number of inner electrodes, etc.

[0049] 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 that are opposite to 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 the overlapping area of ​​the first internal electrode 150 and the second internal electrode 160 that overlap each other in the thickness direction (T-axis direction).

[0050] 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 along 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. In addition, a region between the active region and the third surface S3 of the ceramic body 110 and a region between the active region and the fourth surface S4 of the ceramic body 110 may also be referred to as an edge region.

[0051] The first cover layer 143 and the second cover layer 145 may be disposed outside the active region in the thickness direction (T-axis direction).

[0052] The first cover layer 143 is disposed between the fifth surface S5 of the ceramic body 110 and the inner electrode closest to the fifth surface S5 of the ceramic body 110. The second cover layer 145 is disposed between the sixth surface S6 of the ceramic body 110 and the inner electrode closest to the sixth surface S6 of the ceramic body 110.

[0053] That is, the first cover layer 143 may be 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. The first cover layer 143 and the second cover layer 145 may have the same composition as that of 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. In addition, the first cover layer 143 and the second cover layer 145 may have a composition different from that of the dielectric layer 140.

[0054] The first and second capping layers 143 and 145 may serve to prevent damage to the first and second internal electrodes 150 and 160 due to physical stress or chemical stress.

[0055] The dielectric layer 140 may include a ceramic material having a high dielectric constant. For example, the ceramic material may include a dielectric ceramic including a component such as BaTiO3, CaTiO3, SrTiO3, or CaZrO3. In addition, auxiliary components such as manganese (Mn), iron (Fe), chromium (Cr), cobalt (Co), and nickel (Ni) may be included in these components. For example, the dielectric layer 140 may include a BaTiO3 in which calcium (Ca), zirconium (Zr), etc. are partially dissolved in the BaTiO3. 1-x Ca x )TiO3、Ba(Ti 1-y Ca y )O3、(Ba 1-x Ca x )(Ti 1- y Zr y )O3 or Ba(Ti 1-y Zr y )O3, wherein 0<x<1 and 0<y<1, but the present disclosure is not limited thereto.

[0056] In addition, the dielectric layer 140 may further include one or more of a ceramic additive, an organic solvent, a plasticizer, a binder, and a dispersant. The ceramic additive may be, for example, a transition metal oxide, a transition metal carbide, a rare earth element, magnesium (Mg), or aluminum (Al).

[0057] For example, the average thickness of the dielectric layer 140 may be 0.1 μm to 10 μm, but the embodiment is not limited thereto.

[0058] The first and second external electrodes 120 and 130 are disposed outside the ceramic body 110 .

[0059] For example, the first and second external electrodes 120 and 130 may include nickel (Ni), copper (Cu), palladium (Pd), gold (Au), silver (Ag), cobalt (Co), chromium (Cr), iron (Fe), tin (Sn), platinum (Pt), indium (In), iridium (Ir), rhodium (Rh), zinc (Zn), or alloys thereof.

[0060] The first external electrode 120 is disposed 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 the sixth surface S6. The second external electrode 130 is disposed 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 the sixth surface S6. In other embodiments, the first external electrode 120 and the second external electrode 130 may extend to a portion of at least one of the fifth surface S5 and the sixth surface S6.

[0061] The first external electrode 120 includes a first end portion 121 , a first band portion 123 , and a first edge portion 125 .

[0062] The first end portion 121 covers the first surface S1 of the ceramic body 110 and is electrically connected to the first protrusions 151 of the plurality of first internal electrodes 150 .

[0063] The first interdiffusion portion 171 may be disposed between the first end portion 121 and the first protrusion 151. The first interdiffusion portion 171 may include an alloy or an intermetallic compound (IMC) formed by interdiffusion of a material of the first external electrode 120 and a material of the first internal electrode 150.

[0064] The presence and composition of the first interdiffusion portion 171 can be determined by performing energy dispersive spectroscopy (EDS) analysis. For example, a multilayer ceramic capacitor is manufactured and then mounted in an epoxy resin mold, and the length (L axis direction)-thickness direction (T axis direction) surface is ground to a position of about 1 / 2 of the width of the multilayer ceramic capacitor along the width direction (W axis direction), and polished with diamond paste to prepare a cross-sectional sample. In the prepared cross-sectional sample, the following positions are measured with a field emission (FE)-transmission electron microscope (TEM) and energy dispersive spectroscopy elemental analysis (EDS elemental analysis) is performed to determine the presence and composition of the first interdiffusion portion 171: the position is about 70 μm away from the interface of the first external electrode and the ceramic body or the interface of the second external electrode and the ceramic body in the direction toward the plating layer (described below), and the first external electrode or the second external electrode can be seen from the position.

[0065] For example, if the material of the first inner electrode 150 includes nickel (Ni), the material of the first outer electrode 120 may include silver (Ag), gold (Au), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), tin (Sn), platinum (Pt), palladium (Pd), or alloys thereof.

[0066] As another example, if the material of the first inner electrode 150 includes copper (Cu), the material of the first outer electrode 120 may include silver (Ag), gold (Au), cobalt (Co), chromium (Cr), iron (Fe), indium (In), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), rhodium (Rh), tin (Sn), zinc (Zn), or alloys thereof.

[0067] As yet another example, if the material of the first internal electrode 150 includes palladium (Pd), the material of the first external electrode 120 may include copper (Cu), iron (Fe), nickel (Ni), rhodium (Rh), tin (Sn), or alloys thereof.

[0068] As another example, if the material of the first inner electrode 150 includes silver (Ag), the material of the first outer electrode 120 may include gold (Au), cobalt (Co), chromium (Cr), iron (Fe), indium (In), nickel (Ni), palladium (Pd), tin (Sn), zinc (Zn), or alloys thereof.

[0069] The first interdiffusion portion 171 may contact the first protrusion 151 of the first internal electrode 150. The first interdiffusion portion 171 may surround the first protrusion 151 of the first internal electrode 150. The first interdiffusion portion 171 may be disposed on the first surface S1 of the ceramic body 110. The first interdiffusion portion 171 may contact the first surface S1 of the ceramic body 110. For example, the first interdiffusion portion 171 may contact and surround the first protrusion 151 of the first internal electrode 150, and contact the first surface S1 of the ceramic body 110.

[0070] The cross-sectional shape of the first interdiffusion portion 171 may be circular, triangular, or quadrilateral, but the present embodiment is not limited thereto. The cross-sectional shape of the first interdiffusion portion 171 may be confirmed based on an optical microscope photograph or a scanning electron microscope (SEM) photograph of a cross section taken along the length direction (L direction)-thickness direction (T direction) at the center in the width direction (W direction) of the ceramic body 110.

[0071] In addition, the length of the first interdiffusion portion 171 is greater than that of the first protrusion 151 . The length of the first interdiffusion portion 171 may be greater than or equal to 0.5 μm and less than or equal to 2 μm, and the length of the first protrusion 151 may be less than that of the first interdiffusion portion 171 .

[0072] If the length of the first interdiffusion portion 171 is less than 0.5 μm, the length of the first protrusion 151 is too short, so there is a possibility of poor electrical connection between the first internal electrode 150 and the first external electrode 120, and a short circuit may occur. In addition, if the length of the first interdiffusion portion 171 exceeds 2 μm, the continuity of the first external electrode 120 may be reduced.

[0073] The length of the first interdiffusion portion 171 and the length of the first protrusion 151 can be confirmed based on an optical microscope photograph or a scanning electron microscope (SEM) photograph of a cross section taken along the length direction (L axis direction)-thickness direction (T axis direction) at the center in the width direction (W axis direction) of the ceramic body 110. The length of the first interdiffusion portion 171 may be the arithmetic average of the following distances: the distance in the length direction (L-axis direction) between the outer surfaces of the three uppermost first interdiffusion portions 171 of the ceramic body 110 shown in the above cross-sectional photograph that are away from the first surface S1 of the ceramic body 110 and the first surface S1 of the ceramic body 110, the distance in the length direction (L-axis direction) between the outer surfaces of the three lowermost first interdiffusion portions 171 of the ceramic body 110 shown in the above cross-sectional photograph that are away from the first surface S1 of the ceramic body 110 and the first surface S1 of the ceramic body 110, and the distance in the length direction (L-axis direction) between the outer surfaces of the three central first interdiffusion portions 171 of the ceramic body 110 shown in the above cross-sectional photograph that are away from the first surface S1 of the ceramic body 110 and the first surface S1 of the ceramic body 110. In addition, the length of the first protrusion 151 may be the arithmetic mean of the lengths of the three uppermost first protrusions 151 of the ceramic body 110 shown in the above cross-sectional photograph in the length direction (L-axis direction), the lengths of the three lowermost first protrusions 151 of the ceramic body 110 shown in the above cross-sectional photograph in the length direction (L-axis direction), and the lengths of the three central first protrusions 151 of the ceramic body 110 shown in the above cross-sectional photograph in the length direction (L-axis direction). The length of the first interdiffusion portion 171 and the length of the first protrusion 151 may be measured by a standard method that will be easily understood and comprehended by a person of ordinary skill in the art.

[0074] In other embodiments, the first end portion 121 may cover a portion of the first surface S1 of the ceramic body 110 .

[0075] The first band portion 123 extends from the first end portion 121 to cover at least a portion of each 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.

[0076] The first edge portion 125 may be a portion connecting the first end portion 121 and the first belt portion 123 .

[0077] The second external electrode 130 includes a second end portion 131 , a second band portion 133 , and a second edge portion 135 .

[0078] The second end portion 131 covers the second surface S2 of the ceramic body 110 and is electrically connected to the second protrusions 161 of the plurality of second internal electrodes 160 .

[0079] The second interdiffusion portion 173 may be disposed between the second end portion 131 and the second protrusion 161. The second interdiffusion portion 173 may include an alloy or an intermetallic compound (IMC) formed by interdiffusion of materials of the second external electrode 130 and the second internal electrode 160.

[0080] The second interdiffusion portion 173 may contact the second protrusion 161 of the second internal electrode 160. The second interdiffusion portion 173 may surround the second protrusion 161 of the second internal electrode 160. The second interdiffusion portion 173 may be disposed on the second surface S2 of the ceramic body 110. The second interdiffusion portion 173 may contact the second surface S2 of the ceramic body 110. For example, the second interdiffusion portion 173 may contact and surround the second protrusion 161 of the second internal electrode 160, and contact the second surface S2 of the ceramic body 110.

[0081] The cross-sectional shape of the second interdiffusion portion 173 may be circular, triangular, or quadrilateral, but the present embodiment is not limited thereto. The cross-sectional shape of the second interdiffusion portion 173 may be confirmed based on an optical microscope photograph or a scanning electron microscope (SEM) photograph of a cross section taken along the length direction (L direction)-thickness direction (T direction) at the center in the width direction (W direction) of the ceramic body 110.

[0082] In addition, the length of the second interdiffusion portion 173 is greater than that of the second protrusion 161 . The length of the second interdiffusion portion 173 may be greater than or equal to 0.5 μm and less than or equal to 2 μm, and the length of the second protrusion 161 may be less than that of the second interdiffusion portion 173 .

[0083] If the length of the second interdiffusion portion 173 is less than 0.5 μm, the length of the second protrusion 161 is too short, so there is a possibility of poor electrical connection between the second inner electrode 160 and the second outer electrode 130, and a short circuit may occur. In addition, if the length of the second interdiffusion portion 173 exceeds 2 μm, the continuity of the second outer electrode 130 may be reduced.

[0084] Except for the position of the second interdiffusion portion 173 , the remaining configuration thereof, such as structure and composition, is the same as or corresponds to that of the first interdiffusion portion 171 , and thus a redundant description thereof will be omitted.

[0085] In other embodiments, the second end portion 131 may cover a portion of the second surface S2 of the ceramic body 110 .

[0086] The second band portion 133 extends from the second end portion 131 to cover at least a portion of each 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.

[0087] The second edge portion 135 may be a portion connecting the second end portion 131 and the second belt portion 133 .

[0088] Based on an optical microscope photograph or a scanning electron microscope (SEM) photograph of a cross section taken along the length direction (L axis direction)-thickness direction (T axis direction) at the center in the width direction (W axis direction) of the multilayer ceramic capacitor 1000, in the multilayer ceramic capacitor 1000 shown in the above cross-sectional photograph, 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 above curved shape may be a curved shape having a tangent 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 the slope of the tangent changes in the opposite direction).

[0089] In addition, the first external electrode 120 may be covered by the first plating layer 180 , and the second external electrode 130 may be covered by the second plating layer 190 .

[0090] The first plating layer 180 and the second plating layer 190 may each include a plurality of layers. For example, the first plating layer 180 may include a first layer 181 covering the first external electrode 120, a second layer 183 covering the first layer 181, and a third layer 185 covering the second layer 183. The first layer 181 may include nickel (Ni), the second layer 183 may include copper (Cu), and the third layer 185 may include tin (Sn), but the present embodiment is not limited thereto.

[0091] In addition, the second plating layer 190 may include a first layer 191 covering the second external electrode 130, a second layer 193 covering the first layer 191, and a third layer 195 covering the second layer 193. The first layer 191 may include nickel (Ni), the second layer 193 may include copper (Cu), and the third layer 195 may include tin (Sn), but the embodiment is not limited thereto.

[0092] According to the present disclosure, since the internal electrode protrudes from the surface of the ceramic body, the interdiffusion layer (ie, the above-mentioned interdiffusion part) can be formed only outside the ceramic body. That is, according to the present disclosure, the interdiffusion layer is difficult to be formed inside the ceramic body.

[0093] Unlike the present disclosure, if there is no protrusion in the inner electrode, that is, if the inner electrode does not protrude from the surface of the ceramic body, the interdiffusion layer may be formed to the inside of the ceramic body. In this case, there is a possibility that the interdiffusion layer may expand inside the ceramic body and cause radiation cracks.

[0094] In addition, according to the present disclosure, the interdiffusion layer can also suppress moisture penetration, thereby preventing degradation of the multilayer ceramic capacitor.

[0095] In addition, according to the present disclosure, the inner electrode includes a protrusion, so that the contact area between the inner electrode and the outer electrode is larger than that without the protrusion. Therefore, according to the present disclosure, the inner electrode and the outer electrode can be better connected.

[0096] While the disclosure has been described in connection with what are presently considered to be practical embodiments, it will be understood that the disclosure is not limited to the disclosed embodiments, but on the contrary, the disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0097] <Description of symbols>

[0098] 1000: Multilayer ceramic capacitors

[0099] 110: Ceramic body

[0100] 120: First outer electrode

[0101] 121: First end

[0102] 123: First belt

[0103] 125: First edge

[0104] 130: Second outer electrode

[0105] 131: Second end

[0106] 133: Second belt

[0107] 135: Second edge

[0108] 140: Dielectric layer

[0109] 143: First covering layer

[0110] 145: Second covering layer

[0111] 150: First inner electrode

[0112] 151: The first protrusion

[0113] 160: Second inner electrode

[0114] 161: Second protrusion

[0115] 171: First interdiffusion section

[0116] 173: Second interdiffusion section

[0117] 180: First coating

[0118] 190: Second coating

[0119] 181, 191: First floor

[0120] 183, 193: Second floor

[0121] 185, 195: The third floor.

Claims

1. A multilayer ceramic capacitor comprising: a ceramic body including stacked dielectric layers and internal electrodes; An external electrode, disposed outside the ceramic body; as well as an interdiffusion portion including an alloy of the material of the inner electrode and the material of the outer electrode or an intermetallic compound of the material of the inner electrode and the material of the outer electrode, At least one of the internal electrodes includes a protrusion that protrudes from the first surface of the ceramic body and contacts the interdiffusion portion.

2. The multilayer ceramic capacitor according to claim 1, wherein The interdiffusion portion surrounds the protrusion.

3. The multilayer ceramic capacitor according to claim 1, wherein The interdiffusion portion is disposed on the first surface of the ceramic body.

4. The multilayer ceramic capacitor according to claim 1, wherein A material of the at least one of the internal electrodes includes nickel, copper, palladium, silver, iron, or an alloy thereof.

5. The multilayer ceramic capacitor according to claim 1, wherein The material of the external electrode includes nickel, copper, palladium, gold, silver, cobalt, chromium, iron, tin, platinum, indium, iridium, rhodium, zinc or alloys thereof.

6. The multilayer ceramic capacitor according to claim 1, wherein The length of the interdiffusion portion in the length direction of the ceramic body is greater than the length of the protrusion of the at least one of the internal electrodes in the length direction.

7. The multilayer ceramic capacitor according to claim 1, wherein: The length of the interdiffusion portion in the longitudinal direction of the ceramic body is greater than or equal to 0.5 μm and less than or equal to 2 μm.

8. The multilayer ceramic capacitor of claim 1, further comprising: A plating layer covers the outer electrode.

9. The multilayer ceramic capacitor according to claim 8, wherein: The coating comprises: a first layer, covering the outer electrode, a second layer, covering the first layer, and The third layer covers the second layer.

10. The multilayer ceramic capacitor according to claim 9, wherein The first layer comprises nickel, The second layer includes copper, and The third layer includes tin.

11. The multilayer ceramic capacitor according to claim 1, wherein Each of the inner electrodes includes a protrusion protruding from the first surface of the ceramic body, and The interdiffusion portion includes a plurality of interdiffusion portions respectively surrounding the protrusions.

12. The multilayer ceramic capacitor according to claim 11, wherein The plurality of interdiffusion portions are spaced apart from one another.

13. The multilayer ceramic capacitor according to any one of claims 1 to 12, wherein: The external electrode includes an end portion, a band portion, and an edge portion, wherein the end portion covers a portion of the first surface of the ceramic body, the band portion extends from the end portion to cover at least a portion of four surfaces of the ceramic body connected to the first surface, and the edge portion connects the end portion and the band portion.

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