Multilayer electronic component

Abstract

The present disclosure provides a multilayer electronic component including: a body including a dielectric layer and an internal electrode; and an external electrode disposed on the body, in which the external electrode may include: a connection electrode layer disposed on the body and connected to the internal electrode and including a conductive metal; a band electrode layer in contact with the connection electrode layer, disposed on the main body, and including a conductive polymer; and a plating layer provided on the connection electrode layer and the band electrode layer, and the conductive metal may include at least one selected from the group consisting of palladium (Pd), silver (Ag), rhodium (Rh), and ruthenium (Ru).

Description

[0001] This application claims the benefit of priority from Korean Patent Application No. 10-2023-0158968 filed in the Korean Intellectual Property Office on November 16, 2023, the disclosure of which is incorporated herein in its entirety by reference. Technical Field

[0002] The present disclosure relates to a multi-layer electronic assembly. Background Art

[0003] Multilayer ceramic capacitors (MLCC, a type of multilayer electronic component) are chip-type capacitors that are mounted on printed circuit boards of various types of electronic products such as image display devices (including liquid crystal displays (LCDs) and plasma display panels (PDPs)), computers, and mobile phones, and are used to charge or discharge them.

[0004] Multilayer ceramic capacitors are used as components in various electronic devices because they have a small size, ensure high capacitance, and are easy to mount. As various electronic devices such as computers and mobile devices are miniaturized and high output power is achieved, the demand for miniaturization and high capacitance of multilayer ceramic capacitors is also increasing.

[0005] The application range of such multilayer ceramic capacitors is expanding, not only for information technology (IT) but also for industrial applications such as electric vehicles and electronic applications, and high reliability and durability are required. In order to manufacture multilayer ceramic capacitors that operate stably in various extreme environments with a ceramic body (brittle material), a structure or material that suppresses or buffers stress from external conditions or processing is required. If the stress from external conditions or processing is not sufficiently prevented, there may be a risk of problems such as reliability degradation or short circuits.

[0006] Therefore, a method of changing the structure or material of an external electrode portion mounted on a board to protect the body from external impact has been applied. Summary of the invention

[0007] An aspect of the present disclosure is to provide a multilayer electronic component having enhanced bending strength and impact resistance.

[0008] An aspect of the present disclosure is to provide a multilayer electronic component having improved reliability and durability.

[0009] However, aspects of the present disclosure are not limited to the above and may be more easily understood in describing specific example embodiments of the present disclosure.

[0010] A multilayer electronic component according to some example embodiments of the present disclosure may include: a body including a dielectric layer and internal electrodes alternately arranged with the dielectric layer in a first direction, and including a first surface and a second surface opposite to each other in the first direction, a third surface and a fourth surface connected to the first surface and the second surface and opposite to each other in the second direction, and a fifth surface and a sixth surface connected to the first surface, the second surface, the third surface and the fourth surface and opposite to each other in the third direction; and an external electrode disposed on the body, and the external electrode may include a connecting electrode layer, a strip electrode layer, and a plating layer, the connecting electrode layer being disposed on the third surface and the fourth surface and connected to the internal electrode and including a conductive metal, the strip electrode layer being in contact with the connecting electrode layer, being disposed on a portion of the first surface and the second surface and / or a portion of the fifth surface and the sixth surface and including a conductive polymer, the plating layer being disposed on the connecting electrode layer and the strip electrode layer, and the conductive metal may include at least one selected from the group consisting of palladium (Pd), silver (Ag), rhodium (Rh), and ruthenium (Ru).

[0011] One of various effects of the present disclosure may be to enhance bending strength and impact resistance of a multilayer electronic component.

[0012] One of various effects of the present disclosure may be to improve reliability and durability of a multilayer electronic component.

[0013] However, the advantages and effects of the present application are not limited to the foregoing and may be more easily understood in the course of describing specific exemplary embodiments of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The above and other aspects, features and advantages of the present disclosure will be more clearly understood through the following detailed description in conjunction with the accompanying drawings, in which: Figure 1 is a perspective view schematically illustrating a multilayer electronic component according to an example embodiment of the present disclosure; Figure 2 An exploded perspective view schematically shows a stacked structure of inner electrodes; Figure 3 is along Figure 1 A schematic cross-sectional view taken along line II' of ; Figure 4 is along Figure 1 A schematic cross-sectional view taken along line II-II'; and Figure 5 Schematically shows Figure 3 Magnified view of area P. DETAILED DESCRIPTION

[0015] Hereinafter, some example embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the example embodiments of the present disclosure may be illustrated in many different forms and should not be construed as being limited to the specific embodiments set forth herein. The example embodiments disclosed herein are provided to enable those skilled in the art to better explain the present disclosure. Therefore, in the accompanying drawings, for the sake of clarity, the shapes and sizes of the elements may be exaggerated, and the same reference numerals will always be used to represent the same elements.

[0016] In addition, in order to clearly describe the present disclosure, the contents irrelevant to the description are omitted in the drawings, and since the size and thickness of each component in the drawings are arbitrarily illustrated for the convenience of description, the present disclosure is not limited thereto. In addition, the same reference numerals are used to describe components having the same functions within the same scope of the concept. Throughout the specification, unless otherwise specified, when a part is described as "including" or "comprising" a component, this indicates that other components are not excluded and other components may be further included.

[0017] In the drawings, a first direction may be defined as a thickness direction, a second direction may be defined as a length direction, and a third direction may be defined as a width direction.

[0018] Multilayer electronic components Figure 1 is a perspective view schematically illustrating a multilayer electronic component according to an example embodiment of the present disclosure.

[0019] Figure 2 An exploded perspective view schematically shows a stacked structure of internal electrodes.

[0020] Figure 3 is along Figure 1 Schematic cross-sectional view taken along line II'.

[0021] Figure 4 It is along Figure 1 Schematic cross-sectional view taken along line II-II'.

[0022] Figure 5 Schematically shows Figure 3 Magnified view of area P.

[0023] In the following, reference will be made to Figures 1 to 5 A multilayer electronic component according to some example embodiments of the present disclosure is described in detail. A multilayer ceramic capacitor will be described as an example of a multilayer electronic component, but the multilayer electronic component of the present disclosure can also be applied to various electronic products using a dielectric composition, such as an inductor, a piezoelectric element, a varistor, or a thermistor.

[0024] A multilayer electronic component 100 according to some example embodiments of the present disclosure may include: a body 110 including a dielectric layer 111 and internal electrodes 121 and 122 arranged alternately with the dielectric layer 111 in a first direction, and including a first surface 1 and a second surface 2 opposite to each other in the first direction, a third surface 3 and a fourth surface 4 connected to the first surface 1 and the second surface 2 and opposite to each other in the second direction, and a fifth surface 5 and a sixth surface 6 connected to the first surface 1, the second surface 2, the third surface 3, and the fourth surface 4 and opposite to each other in the third direction; and external electrodes 131 and 132 disposed on the body 110, and the external electrodes 131 and 132 may include connecting electrode layers 131a-1 and 131b-2. 2a-1, electrode layers 131a-2 and 132a-2, and a plating layer, the connecting electrode layers 131a-1 and 132a-1 are arranged on the third surface 3 and the fourth surface 4 and are connected to the internal electrodes 121 and 122 and include a conductive metal, the electrode layers 131a-2 and 132a-2 are in contact with the connecting electrode layers 131a-1 and 132a-1 and are arranged on a portion of the first surface 1 and the second surface 2 and include a conductive polymer, the plating layer is arranged on the connecting electrode layers 131a-1 and 132a-1 and the electrode layers 131a-2 and 132a-2, and the conductive metal may include at least one selected from the group consisting of palladium (Pd), silver (Ag), rhodium (Rh) and ruthenium (Ru).

[0025] The body 110 may have dielectric layers 111 and internal electrodes 121 and 122 that are alternately stacked.

[0026] More specifically, the body 110 may include therein a capacitance forming part Ac for forming capacitance, the capacitance forming part Ac including first and second internal electrodes 121 and 122 alternately arranged to face each other and a dielectric layer 111 interposed therebetween.

[0027] There is no particular limitation on the specific shape of the main body 110, but Figure 1 As shown in FIG, the body 110 may have a hexahedral shape or a shape similar to the hexahedral shape. Due to shrinkage of the ceramic powder included in the body 110 during the sintering process, the body 110 may not have a hexahedral shape with perfect straight lines but may generally have a hexahedral shape.

[0028] The body 110 may have a first surface 1 and a second surface 2 opposite to each other in a first direction, a third surface 3 and a fourth surface 4 connected to the first surface 1 and the second surface 2 and opposite to each other in the second direction, and a fifth surface 5 and a sixth surface 6 connected to the first surface 1, the second surface 2, the third surface 3 and the fourth surface 4 and opposite to each other in a third direction.

[0029] In a state where a plurality of dielectric layers 111 included in the main body 110 are sintered, adjacent dielectric layers 111 may be integrated such that it is difficult to identify the boundary therebetween without using a scanning electron microscope (SEM).

[0030] There is no limitation on the material included in the dielectric layer 111a as long as sufficient electrostatic capacitance can be obtained therefrom. Generally, perovskite (ABO3)-based materials can be used, and for example, barium titanate-based materials, lead composite perovskite-based materials, or strontium titanate-based materials can be used. The barium titanate-based material may include BaTiO3-based ceramic particles, and examples of the BaTiO3-based ceramic particles may include BaTiO3 and (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) or Ba(Ti 1-y Zr y )O3 (0 < y < 1).

[0031] In addition, as the material included in the dielectric layer 111, various ceramic additives, organic solvents, binders, dispersants, etc. can be added to particles such as barium titanate (BaTiO3) according to the purpose of the present disclosure.

[0032] There is no limitation on the thickness td of the dielectric layer 111.

[0033] To ensure the reliability of the multilayer electronic component 100 in a high-voltage environment, the thickness of the dielectric layer 111 may be less than or equal to 10.0 μm. In addition, to achieve miniaturization and high capacitance of the multilayer electronic component 100, the thickness of the dielectric layer 111 may be less than or equal to 3.0 μm, and to more easily achieve miniaturization and high capacitance, the thickness of the dielectric layer 111 may be less than or equal to 1.0 μm, preferably less than or equal to 0.6 μm, and more preferably less than or equal to 0.4 μm.

[0034] Here, the thickness td of the dielectric layer 111 may refer to the thickness td of the dielectric layer 111 disposed between adjacent first internal electrode 121 and second internal electrode 122.

[0035] In addition, the thickness td of the dielectric layer 111 may refer to the first-direction dimension of the dielectric layer 111. In addition, the thickness td of the dielectric layer 111 may refer to the average thickness of the dielectric layer 111, and may refer to the average dimension of the dielectric layer 111 in the first direction.

[0036] The average size of the dielectric layer 111 in the first direction can be measured by scanning the first and second direction cross sections of the body 110 with a scanning electron microscope (SEM) at a magnification of 10,000 times. More specifically, the average size of one dielectric layer 111 in the first direction can be an average value calculated by measuring the first direction size of one dielectric layer 111 at 10 regions spaced apart from each other at equal intervals in the second direction in the scanned image. The 10 regions spaced apart from each other at equal intervals can be specified in the capacitor forming portion Ac. In addition, when the average value is obtained by extending the average thickness measurement to 10 dielectric layers 111, the average thickness of the dielectric layer 111 in the first direction can be further generalized.

[0037] The internal electrodes 121 and 122 may be alternately stacked with the dielectric layers 111 .

[0038] The inner electrode may include first and second inner electrodes 121 and 122 which may be alternately arranged to face each other with the dielectric layer 111 interposed therebetween and may be exposed to the third and fourth surfaces 3 and 4 of the body 110 , respectively.

[0039] More specifically, the first inner electrode 121 may be spaced apart from the fourth surface 4 and may be exposed through the third surface 3, and the second inner electrode 122 may be spaced apart from the third surface 3 and may be exposed through the fourth surface 4. The first outer electrode 131 may be disposed on the third surface 3 of the body 110 and may be connected to the first inner electrode 121, and the second outer electrode 132 may be disposed on the fourth surface 4 of the body 110 and may be connected to the second inner electrode 122.

[0040] That is, the first internal electrode 121 may be connected to the first external electrode 131 without being connected to the second external electrode 132, and the second internal electrode 122 may be connected to the second external electrode 132 without being connected to the first external electrode 131. In this case, the first internal electrode 121 and the second internal electrode 122 may be electrically separated from each other by the dielectric layer 111 disposed therebetween.

[0041] In addition, the body 110 may be formed by alternately stacking ceramic green sheets on which the conductive paste for the first internal electrode 121 is printed and ceramic green sheets on which the conductive paste for the second internal electrode 122 is printed, and then sintering the ceramic green sheets.

[0042] The material included in the internal electrodes 121 and 122 is not particularly limited, and any material having excellent conductivity may be used. For example, the internal electrodes 121 and 122 may include one or more selected from the group consisting of nickel (Ni), copper (Cu), palladium (Pd), silver (Ag), gold (Au), platinum (Pt), tin (Sn), tungsten (W), titanium (Ti), and alloys thereof.

[0043] In addition, the internal electrodes 121 and 122 may be formed by printing a conductive paste for internal electrodes including one or more selected from the group consisting of nickel (Ni), copper (Cu), palladium (Pd), silver (Ag), gold (Au), platinum (Pt), tin (Sn), tungsten (W), titanium (Ti), and alloys thereof on a ceramic green sheet. The printing method of the conductive paste for internal electrodes may be a screen printing method or a gravure printing method, but the present disclosure is not limited thereto.

[0044] In addition, the thickness te of the internal electrodes 121 and 122 is not limited.

[0045] In order to ensure the reliability of the multilayer electronic component 100 under a high voltage environment, the thickness te of the internal electrodes 121 and 122 may be less than or equal to 3.0 μm. In addition, in order to achieve miniaturization and high capacitance of the multilayer electronic component 100, the thickness of the internal electrodes 121 and 122 may be less than or equal to 1.0 μm, and in order to more easily achieve ultra-miniaturization and high capacitance, the thickness of the internal electrodes 121 and 122 may be less than or equal to 0.6 μm, and more preferably, less than or equal to 0.4 μm.

[0046] Here, the thickness te of the internal electrodes 121 and 122 may refer to a first direction dimension of the internal electrodes 121 and 122. In addition, the thickness te of the internal electrodes 121 and 122 may refer to an average thickness of the internal electrodes 121 and 122 and may refer to an average dimension of the internal electrodes 121 and 122 in the first direction.

[0047] The average size of the internal electrodes 121 and 122 in the first direction can be measured by scanning an image of a first direction and a second direction cross section of the body 110 with a scanning electron microscope (SEM) at a magnification of 10,000 times. More specifically, the average size of one internal electrode in the first direction can be an average value calculated by measuring the first direction size of one internal electrode at 10 regions spaced apart from each other at equal intervals in the second direction in the scanned image. The 10 regions spaced apart from each other at equal intervals can be specified in the capacitor forming portion Ac. In addition, when the average value is obtained by extending the average thickness measurement to 10 internal electrodes, the average thickness of the internal electrode in the first direction can be further generalized.

[0048] In addition, in some example embodiments of the present disclosure, an average thickness td of at least one of the plurality of dielectric layers 111 and an average thickness te of at least one of the plurality of internal electrodes 121 and 122 may satisfy 2×te <td。

[0049] In other words, the average thickness td of one dielectric layer 111 may be greater than twice the average thickness te of one internal electrode 121 or 122. Preferably, the average thickness td of the plurality of dielectric layers 111 may be greater than twice the average thickness te of the plurality of internal electrodes 121 and 122.

[0050] Generally, high voltage electronic components have major reliability issues due to the reduction of breakdown voltage (BDV) under high voltage environments.

[0051] Therefore, in order to prevent a decrease in breakdown voltage under a high voltage environment, the average thickness td of the dielectric layer 111 may be made greater than twice the average thickness te of the internal electrodes 121 and 122 so that the thickness of the dielectric layer, which is the distance between the internal electrodes, may be increased, thereby improving breakdown voltage (BDV) characteristics.

[0052] When the average thickness td of the dielectric layer 111 is less than or equal to twice the average thickness te of the internal electrodes 121 and 122 , the average thickness of the dielectric layer (the distance between the internal electrodes) may be thin, which may reduce a breakdown voltage and a short circuit may occur between the internal electrodes.

[0053] In addition, the body 110 may include cover parts 112 and 113 disposed on both surfaces of the capacitance forming part Ac in the first direction.

[0054] Specifically, the covering portions 112 and 113 may include a first covering portion 112 disposed on one surface of the capacitor forming portion in the first direction and a second covering portion 113 disposed on another surface of the capacitor forming portion in the first direction, and more specifically, the covering portions 112 and 113 may include an upper covering portion 112 (i.e., the first covering portion 112) disposed above the capacitor forming portion in the first direction and a lower covering portion 113 (i.e., the second covering portion 113) disposed below the capacitor forming portion in the first direction.

[0055] The upper covering portion 112 and the lower covering portion 113 may be formed by stacking a single dielectric layer 111a or two or more dielectric layers 111a on the upper surface and the lower surface of the capacitor forming portion in the first direction, respectively, and may be mainly used to prevent damage to the internal electrodes 121 and 122 due to physical stress and / or chemical stress.

[0056] The upper and lower covers 112 and 113 do not include the internal electrodes 121 and 122 and may include the same material as the dielectric layer 111a. That is, the upper and lower covers 112 and 113 may include a ceramic material and may include, for example, a barium titanate (BaTiO3)-based ceramic material.

[0057] In addition, the thickness tc of the covering portions 112 and 113 is not limited.

[0058] However, to more easily achieve miniaturization and high capacitance of multilayer electronic component 100 , thickness tc of covers 112 and 113 may be 100 μm or less, preferably 30 μm or less, and more preferably 20 μm or less in ultra-small products.

[0059] Here, the thickness tc of the covers 112 and 113 may refer to the first direction dimension of the covers 112 and 113. In addition, the thickness tc of the covers 112 and 113 may refer to the average thickness of the covers 112 and 113 and may refer to the average dimension of the covers 112 and 113 in the first direction.

[0060] The average size of the covering portions 112 and 113 in the first direction may be measured by scanning an image obtained by scanning a first-direction and a second-direction cross section of the body 110 with a scanning electron microscope (SEM) at a magnification of 10,000 times. More specifically, the average size of the covering portions 112 and 113 in the first direction may refer to an average value calculated by measuring the first-direction sizes of 10 regions of one covering portion in the scanned image that are equally spaced from each other in the second direction.

[0061] In addition, the average size of the covering portion in the first direction measured by the above method may be substantially the same as the average size of the covering portion in the first direction measured in the first and third direction cross sections of the body 110 .

[0062] In addition, the multilayer electronic component 100 may include side edge portions 114 and 115 disposed on both surfaces of the capacitance forming portion Ac in the third direction.

[0063] More specifically, the side edge portions 114 and 115 may include a first side edge portion 114 disposed on one surface of the capacitance forming portion Ac in the third direction and a second side edge portion 115 disposed on the other surface of the capacitance forming portion Ac in the third direction.

[0064] like Figure 4 As shown in , the side edge portions 114 and 115 may refer to regions between end surfaces of the first and second internal electrodes 121 and 122 in the third direction and an outer surface of the body 110 based on first and third direction sections of the body 110 .

[0065] The side edge portions 114 and 115 may be formed by applying a conductive paste to form internal electrodes 121 and 122 on ceramic green sheets except for positions where the side edge portions 114 and 115 are to be formed, and stacking the ceramic green sheets to form a stack, cutting the stack so that the internal electrodes 121 and 122 are exposed to both surfaces of the capacitor forming portion Ac in the third direction to suppress step portions caused by the internal electrodes 121 and 122, and then stacking a single dielectric layer 111 or two or more dielectric layers 111 on both surfaces of the capacitor forming portion Ac in the third direction.

[0066] The side margin parts 114 and 115 may mainly serve to prevent damage of the internal electrodes 121 and 122 due to physical stress and / or chemical stress.

[0067] The first and second side margin parts 114 and 115 do not include the internal electrodes 121 and 122 and may include the same material as the dielectric layer 111. That is, the first and second side margin parts 114 and 115 may include a ceramic material and may include, for example, a barium titanate (BaTiO3)-based ceramic material.

[0068] In addition, the width wm of the first side margin portion 114 and the second side margin portion 115 is not limited.

[0069] However, to more easily achieve miniaturization and high capacitance of the multilayer electronic component 100 , the width wm of the side margin portions 114 and 115 may be 100 μm or less, preferably 30 μm or less, and more preferably 20 μm or less in ultra-small products.

[0070] Here, the width wm of the side margin portions 114 and 115 may refer to the third direction dimension of the side margin portions 114 and 115. In addition, the width wm of the side margin portions 114 and 115 may refer to the average width of the side margin portions 114 and 115, and may refer to the average dimension of the side margin portions 114 and 115 in the third direction.

[0071] The average size of the side edge portions 114 and 115 in the third direction may be measured by scanning an image of the first and third direction cross sections of the body 110 using a scanning electron microscope (SEM) at a magnification of 10,000 times. More specifically, the average size of the side edge portions 114 and 115 in the third direction may refer to an average value calculated by measuring the third direction size of 10 regions of one side edge portion in the scanned image that are equally spaced from each other in the first direction.

[0072] In some example embodiments of the present disclosure, a structure in which the multilayer electronic component 100 has two external electrodes 131 and 132 is described, but the number or shape of the external electrodes 131 and 132 may be changed according to the shapes of the internal electrodes 121 and 122 or other purposes.

[0073] The external electrodes 131 and 132 may be disposed on the body 110 , and may be connected to the internal electrodes 121 and 122 .

[0074] More specifically, the external electrodes 131 and 132 may be disposed on the third surface 3 and the fourth surface 4 of the body 110, respectively, and may include a first external electrode 131 and a second external electrode 132 respectively connected to the first internal electrode 121 and the second internal electrode 122. That is, the first external electrode 131 may be disposed on the third surface 3 of the body and may be connected to the first internal electrode 121, and the second external electrode 132 may be disposed on the fourth surface 4 of the body and may be connected to the second internal electrode 122.

[0075] In addition, the external electrodes 131 and 132 may be provided to extend to a portion of the first surface 1 and the second surface 2 of the body 110, and may also be provided to extend to a portion of the fifth surface 5 and the sixth surface 6 of the body 110. That is, the first external electrode 131 may be provided on a portion of the first surface 1, the second surface 2, the fifth surface 5, and the sixth surface 6 of the body 110 and on the third surface 3 of the body 110, and the second external electrode 132 may be provided on a portion of the first surface 1, the second surface 2, the fifth surface 5, and the sixth surface 6 of the body 110 and on the fourth surface 4 of the body 110.

[0076] In addition, the external electrodes 131 and 132 may be formed by using any material as long as the material has conductivity, such as metal, and a specific material may be determined in consideration of electrical characteristics, structural stability, etc., and the external electrodes 131 and 132 may further have a multi-layered structure.

[0077] For example, the external electrodes 131 and 132 may include electrode layers 131 a and 132 a disposed on the body 110 and a plating layer disposed on the electrode layers 131 a and 132 a .

[0078] Here, the electrode layers 131a and 132a may include connecting electrode layers 131a-1 and 132a-1 and strip electrode layers 131a-2 and 132a-2, wherein the connecting electrode layers 131a-1 and 132a-1 are arranged on the third surface 3 and the fourth surface 4 of the body 110 and are connected to the internal electrodes 121 and 122 and include a conductive metal, and the strip electrode layers 131a-2 and 132a-2 are in contact with the connecting electrode layers 131a-1 and 132a-1 and are arranged on a portion of the first surface 1 and the second surface 2 and / or a portion of the fifth surface 5 and the sixth surface 6 of the body 110 and include a conductive polymer.

[0079] In other words, the first external electrode 131 may include an electrode layer 131a disposed in contact with the body 110. More specifically, the electrode layer 131a may include a connecting electrode layer 131a-1 disposed in contact with the third surface 3 of the body 110 and connected to the first internal electrode 121 and including a conductive metal, and a strip electrode layer 131a-2 in contact with the connecting electrode layer 131a-1 and disposed in contact with a portion of the first surface 1 and the second surface 2 and / or a portion of the fifth surface 5 and the sixth surface 6 of the body 110 and including a conductive polymer.

[0080] The second external electrode 132 may include an electrode layer 132a disposed in contact with the body 110. More specifically, the electrode layer 132a may include a connection electrode layer 132a-1 disposed in contact with the fourth surface 4 of the body 110 and connected to the second internal electrode 122 and including a conductive metal, and a strip electrode layer 132a-2 in contact with the connection electrode layer 132a-1 and disposed in contact with a portion of the first surface 1 and the second surface 2 and / or a portion of the fifth surface 5 and the sixth surface 6 of the body 110 and including a conductive polymer.

[0081] The conductive metal included in the connection electrode layers 131 a - 1 and 132 a - 1 may include at least one selected from the group consisting of palladium (Pd), silver (Ag), rhodium (Rh), and ruthenium (Ru).

[0082] The method of forming the connection electrode layers 131a-1 and 132a-1 is not particularly limited thereto, but the connection electrode layers 131a-1 and 132a-1 may be formed by applying a salt solution including ions of a conductive metal (e.g., at least one selected from the group consisting of palladium (Pd), silver (Ag), rhodium (Rh), and ruthenium (Ru)) to the third and fourth surfaces 3 and 4 of the body and performing heat treatment thereon.

[0083] Since the connection electrode layers 131 a - 1 and 132 a - 1 are formed by coating a salt solution, the connection electrode layers 131 a - 1 and 132 a - 1 may have excellent bonding strength with the body 110 and with first plating layers 131 b and 132 b to be described below.

[0084] In addition, an average thickness of the connection electrode layers 131 a - 1 and 132 a - 1 in the second direction may be greater than or equal to 0.1 μm and less than or equal to 4 μm.

[0085] When the average thickness of the connection electrode layers 131a-1 and 132a-1 satisfies 0.1 μm or more and 4 μm or less, sufficient electrical connectivity with the internal electrodes 121 and 122 can be ensured, and bonding strength with the first plating layers 131b and 132b described later can be excellent.

[0086] When the average thickness of the connection electrode layers 131a-1 and 132a-1 is less than 0.1 μm, since sufficient thickness is not formed, the bonding strength with the first plating layers 131b and 132b may be deteriorated, and thus, there may be a risk of lift-off or delamination of the external electrodes 131 and 132 occurring.

[0087] When the average thickness of the connection electrode layers 131 a - 1 and 132 a - 1 is greater than 4 μm, equivalent series resistance (ESR) may increase, which may make it difficult to achieve miniaturization of the multilayer electronic component 100 .

[0088] In the present disclosure, the average thickness of the connecting electrode layers 131a-1 and 132a-1 may correspond to the average size of the connecting electrode layers 131a-1 and 132a-1 in the second direction. For example, when the first and second direction cross-sections of the multilayer electronic component 100 are observed with a scanning electron microscope (SEM), the average thickness of the connecting electrode layers 131a-1 and 132a-1 may refer to the average value obtained by measuring the second direction size of the connecting electrode layers 131a-1 and 132a-1 at three arbitrary points spaced apart from each other in the first direction, but the present disclosure is not particularly limited thereto. Here, the three arbitrary points spaced apart from each other in the first direction may be selected from the extension line (extended surface) of the edge of the capacitor forming portion Ac in which the internal electrode is disposed in the first direction.

[0089] When the connection electrode layers 131 a - 1 and 132 a - 1 are formed using an ionic salt solution and a heat treatment is performed, the conductive metal of the connection electrode layers 131 a - 1 and 132 a - 1 may be diffused into the internal electrodes 121 and 122 .

[0090] Therefore, the internal electrodes 121 and 122 may include a diffusion portion which is a region contacting the connection electrode layers 131 a - 1 and 132 a - 1 and including a conductive metal.

[0091] That is, the internal electrodes 121 and 122 may include a non-diffusion portion and a diffusion portion, wherein the non-diffusion portion is a region of the internal electrodes 121 and 122 that does not include the conductive metal connecting the electrode layers 131a-1 and 132a-1, and the diffusion portion is a region of the internal electrodes 121 and 122 that includes the conductive metal connecting the electrode layers 131a-1 and 132a-1.

[0092] In addition, in the present disclosure, the non-diffusion portion (not shown) and the diffusion portion (not shown) of the first internal electrode 121 are not shown. Figure 5 , only the non-diffusion portion 122a and the diffusion portion 122b of the second inner electrode 122 are shown using the second inner electrode 122 and the second outer electrode 132 as examples, but it is easy for those skilled in the art to understand that the structures of the non-diffusion portion (not shown) and the diffusion portion (not shown) of the first inner electrode 121 can be understood to be the same as those of the second inner electrode 122.

[0093] In this case, the diffusion portion of the internal electrode may include an alloy between the main component metal of the internal electrodes 121 and 122 and the conductive metal connecting the electrode layers 131 a - 1 and 132 a - 1 .

[0094] In the present disclosure, “main component” may refer to a component occupying a relatively large weight ratio compared to other components, and may refer to a component greater than or equal to 50 wt % based on the weight of the entire composition or the entire dielectric layer.

[0095] For example, in the case where the internal electrodes 121 and 122 include nickel (Ni) as a main component and the connecting electrode layers 131 a - 1 and 132 a - 1 include palladium (Pd), the internal electrodes 121 and 122 may form a diffusion portion due to the diffusion of a conductive metal into the internal electrodes 121 and 122 during a sintering process of the connecting electrode layers 131 a - 1 and 132 a - 1 in a salt solution state, and the diffusion portion may include a nickel-palladium (Ni—Pd) alloy due to an alloy reaction between nickel (Ni) as a main component metal of the internal electrodes 121 and 122 and palladium (Pd) diffused from the connecting electrode layers 131 a - 1 and 132 a - 1.

[0096] The diffusion portion may include an alloy including a main component metal of the inner electrodes 121 and 122 and a conductive metal of the connecting electrode layers 131a-1 and 132a-1, which may reduce the hydrogen diffusion coefficient and may prevent the penetration of external moisture and hydrogen, or the diffusion portions 122a and 122b may prevent the penetration of a plating solution to suppress the degradation of the inner electrodes 121 and 122, thereby preventing an increase in the equivalent series resistance (ESR). In addition, the bonding strength between the inner electrodes 121 and 122 and the connecting electrode layers 131a-1 and 132a-1 may be improved to suppress the occurrence of lift or delamination between the outer electrodes 131 and 132 and the body 110, and the electrical connectivity may also be improved.

[0097] Here, the diffusion parts may be regions of the internal electrodes, each having an average size within 6 μm in the inner direction (second direction) of the body 110 from a point where the internal electrodes 121 and 122 and the connection electrode layers 131 a - 1 and 132 a - 1 contact each other.

[0098] In other words, the diffusion portion may be a region having an average size within 6 μm in the inner direction of the body 110 based on the second direction from the point where the internal electrodes 121 and 122 and the connecting electrode layers 131 a - 1 and 132 a - 1 contact each other, and the average size of the diffusion portion in the second direction may be less than or equal to 6 μm, that is, the average length of the diffusion portion may be less than or equal to 6 μm.

[0099] Since the diffusion portion is formed within an average size of 6 μm along the inner direction of the body 110 from the point where the internal electrodes 121 and 122 and the connecting electrode layers 131 a - 1 and 132 a - 1 contact each other, the hydrogen diffusion coefficient can be reduced to more effectively prevent external moisture and hydrogen penetration, or the diffusion portion can more effectively prevent penetration of the plating solution, thereby suppressing degradation of the internal electrodes 121 and 122 and preventing an increase in the equivalent series resistance (ESR).

[0100] The lower limit of the average size of the diffusion portion is not particularly limited, but may be, for example, 0.1 μm or more.

[0101] Here, the point at which the internal electrodes 121 and 122 and the connection electrode layers 131a-1 and 132a-1 contact each other does not need to be parallel to the surface of the body 110, and may correspond to a point at which the internal electrodes 121 and 122 are introduced into the inside of the body 110 and the connection electrode layers 131a-1 and 132a-1 also penetrate into and contact the inside of the body 110. Alternatively, when the internal electrodes 121 and 122 are shaped to protrude to the outside of the body 110, the point may correspond to a point at which the internal electrodes 121 and 122 protrude to the outside of the body 110 to contact the connection electrode layers 131a-1 and 132a-1, but the present disclosure is not particularly limited thereto.

[0102] As a method of measuring the average size (average length) of the diffusion portion in the second direction, for example, the average size may be obtained by calculating the average value of the maximum value and the minimum value of the second direction size L1 of the diffusion portion, or the average size may be obtained by calculating the average value of the values ​​measured in the second direction at three arbitrary points of the diffusion portion spaced from each other in the first direction (thickness direction) of the diffusion portion. Alternatively, after extracting the region of the diffusion portion from an image obtained using a scanning electron microscope (SEM) by a program, the method of calculating the average value of the second direction size may be used in the program, but the present disclosure is not particularly limited thereto.

[0103] When the diffusion portions 121 b and 122 b exceed an average size of 6 μm in an inner direction of the body 110 from a point where the internal electrodes 121 and 122 and the connection electrode layers 131 a - 1 and 132 a - 1 contact each other, there may be a risk of deterioration of electrical connectivity or increase in equivalent series resistance (ESR) due to excessive diffusion of the conductive metal included in the connection electrode layers 131 a - 1 and 132 a - 1, which may deteriorate electrical characteristics.

[0104] In some example embodiments of the present disclosure, the external electrodes 131 and 132 may not include glass. However, the present disclosure is not particularly limited thereto, and when the connection electrode layers 131a-1 and 132a-1 do not include glass, the strip electrode layers 131a-2 and 132a-2 may include glass, and when the strip electrode layers 131a-2 and 132a-2 do not include glass, the connection electrode layers 131a-1 and 132a-1 may include glass, and both the connection electrode layers 131a-1 and 132a-1 and the strip electrode layers 131a-2 and 132a-2 may not include glass. Details thereof will be described below.

[0105] The connection electrode layers 131 a - 1 and 132 a - 1 may not include glass.

[0106] For a typical sintered electrode, a method of improving adhesion to the body by adding glass to a paste for an external electrode is used, but when the connecting electrode layers 131a-1 and 132a-1 are formed by coating an ionic salt solution, the bonding strength with the body 110 can be excellent even without adding glass, so that glass may not be an essential element, but glass can be added as needed.

[0107] The conductive polymer included in the electrode-bearing layers 131 a - 2 and 132 a - 2 may include at least one selected from the group consisting of polypyrrole, polyaniline, polythiophene, and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS).

[0108] Since the electrode layers 131 a - 2 and 132 a - 2 include a conductive polymer, the electrode layers 131 a - 2 and 132 a - 2 may serve to absorb external impact, thereby improving bending strength and preventing an equivalent series resistance (ESR) from increasing.

[0109] The method of forming the electrode layers 131a-2 and 132a-2 is not particularly limited to this, but the electrode layers 131a-2 and 132a-2 can be formed in the following manner: a solution including at least one of a conductive polymer such as polypyrrole, polyaniline, polythiophene and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is formed on a portion of the first surface 1 and the second surface 2 and / or a portion of the fifth surface 5 and the sixth surface 6 of the body 110 using an inkjet method or the like, and oven drying can be performed in a temperature range of greater than or equal to 100°C and less than or equal to 120°C.

[0110] Here, the solution including the conductive polymer may further include a silane coupling agent and a binder.

[0111] In addition, the electrode-bearing layers 131a-2 and 132a-2 may not include glass.

[0112] For a typical sintered electrode, a method of improving the bonding strength with the body 110 is used by adding glass to the paste for the external electrode, but in the case of the electrode layers 131a-2 and 132a-2 including a conductive polymer, since the electrode layers 131a-2 and 132a-2 include additives such as a silane coupling agent or an adhesive, the adhesion with the body 110 can be excellent even without adding glass, so that glass may not be a necessary element, but glass can be added as needed.

[0113] In addition, the average thickness of the electrode-bearing layers 131 a - 2 and 132 a - 2 in the first direction may be greater than or equal to 0.1 μm and less than or equal to 4 μm.

[0114] Since the average thickness of electrode layers 131a-2 and 132a-2 in the first direction satisfies 0.1 μm or more and 4 μm or less, bending stress applied to multilayer electronic component 100 can be sufficiently absorbed, thereby ensuring sufficient bending strength to prevent cracks.

[0115] When the average thickness of the electrode layers 131a-2 and 132a-2 in the first direction is less than 0.1 μm, the bending strength may not be sufficiently improved due to failure to form a sufficient thickness, and when the average thickness of the electrode layers 131a-2 and 132a-2 is greater than 4 μm, the equivalent series resistance (ESR) may increase and it may be difficult to achieve miniaturization of the multilayer electronic component 100.

[0116] In the present disclosure, the average thickness of the electrode layers 131a-2 and 132a-2 in the first direction may correspond to the average size of the connecting electrode layers 131a-1 and 132a-1 in the second direction. For example, when the first and second direction cross-sections of the multilayer electronic component 100 are observed with a scanning electron microscope (SEM), the average thickness may refer to the average value of the first direction size of the electrode layers 131a-2 and 132a-2 measured at three arbitrary points spaced apart from each other in the second direction, but the present disclosure is not particularly limited thereto. Here, the three arbitrary points spaced apart in the second direction may refer to points in contact with one surface of the body 110, and may be selected from a body region having substantially parallel surfaces rather than a curved edge region.

[0117] In addition, in some example embodiments of the present disclosure, the connecting electrode layers 131a-1 and 132a-1 may not be arranged between the extension line EL3 of the third surface and the extension line EL4 of the fourth surface, and the strip electrode layers 131a-2 and 132a-2 may be arranged between the extension line EL3 of the third surface and the extension line EL4 of the fourth surface.

[0118] This can be achieved by the following method: first, electrode layers 131a-2 and 132a-2 are formed on a portion of the first surface 1 and the second surface 2 and / or a portion of the fifth surface and the sixth surface, and then the electrode layers 131a-2 and 132a-2 formed outside the extension line EL3 of the third surface and the extension line EL4 of the fourth surface are polished using sandblasting, and connecting electrode layers 131a-1 and 132a-1 are formed on the third surface 3 and the fourth surface 4, but the present disclosure is not particularly limited to this.

[0119] More specifically, after forming the electrode layers 131a-2 and 132a-2 on a portion of the first surface 1 and the second surface 2 and / or a portion of the fifth surface and the sixth surface of the body 110, the unnecessary electrode layers 131a-2 and 132a-2 formed on the third surface 3 and the fourth surface 4 of the body 110 may be polished and removed. In addition, sulfuric acid and surfactant treatment may be performed to remove organic substances remaining on the polished surface.

[0120] Next, after washing away the sulfuric acid and the surfactant, oxide regions of the internal electrodes 121 and 122 exposed outside the body 110 may be removed, and a hydrochloric acid aqueous solution treatment may be performed to increase the amount of conductive metal precipitation in the connection electrode layers 131a-1 and 132a-1.

[0121] Next, after washing away the hydrochloric acid solution, the third surface 3 and the fourth surface 4 of the body 110 are immersed in an ionic salt solution to form connecting electrode layers 131a-1 and 132a-1. In this case, sufficient ion circulation can be achieved by stirring the ionic salt solution, so that the connecting electrode layers 131a-1 and 132a-1 with substantially uniform thickness are grown.

[0122] To this end, since the connecting electrode layers 131a-1 and 132a-1 are not arranged between the extension line EL3 on the third surface and the extension line EL4 on the fourth surface, and the electrode layers 131a-2 and 132a-2 are arranged between the extension line EL3 on the third surface and the extension line EL4 on the fourth surface, the bonding strength with the first plating layers 131b and 132b can be improved, and impact resistance can be provided while blocking the external moisture penetration path.

[0123] The plating layers 131 b , 132 b , 131 c , 132 c , 131 d , and 132 d may be used to improve mounting characteristics.

[0124] The types of the plating layers 131b, 132b, 131c, 132c, 131d, and 132d are not particularly limited, and the external electrodes 131 and 132 may include single-layer plating layers 131b and 132b, respectively, including one or more selected from the group consisting of copper (Cu), nickel (Ni), tin (Sn), silver (Ag), palladium (Pd), and alloys thereof, and the external electrodes 131 and 132 may include a plurality of plating layers, and for example, the external electrodes 131 and 132 may include two-layer plating layers 131b and 131c and 132b and 132c, respectively, or three-layer plating layers 131b, 131c, and 131d and 132b, 132c, and 132d, respectively.

[0125] For a more specific example of the plating layers 131b, 132b, 131c, 132c, 131d and 132d, the plating layers 131b, 132b, 131c, 132c, 131d and 132d may include first plating layers 131b and 132b disposed on the connecting electrode layers 131a-1 and 132a-1 and the strip electrode layers 131a-2 and 132a-2 and including copper (Cu), second plating layers 131c and 132c disposed on the first plating layers 131b and 132b, respectively, and including nickel (Ni), and third plating layers 131d and 132d disposed on the second plating layers 131c and 132c, respectively, and including tin (Sn).

[0126] Here, the average thickness of the first plating layers 131b and 132b may be greater than or equal to 5μm and less than or equal to 8μm, the average thickness of the second plating layers 131c and 132c may be greater than or equal to 2μm and less than or equal to 4μm, and the average thickness of the third plating layers 131d and 132d may be greater than or equal to 2μm and less than or equal to 4μm.

[0127] In the present disclosure, the average thickness of the first plating layers 131b and 132b, the second plating layers 131c and 132c, and the third plating layers 131d and 132d may correspond to the average size of each of the first plating layers 131b and 132b, the second plating layers 131c and 132c, and the third plating layers 131d and 132d in the second direction on the third surface 3 and the fourth surface 4, or the average size of a portion on the first surface 1 and the second surface 2 and / or a portion of the fifth surface and the sixth surface in the first direction.

[0128] For example, when the first and second direction cross sections of the multilayer electronic component 100 are observed with a scanning electron microscope (SEM), the average thickness of the first plating layers 131b and 132b, the second plating layers 131c and 132c, and the third plating layers 131d and 132d may refer to an average value obtained by measuring the second direction dimension of each of the first to third plating layers 131b, 132b, 131c, 132c, 131d, and 132d at three arbitrary points spaced apart from each other in the first direction, but the present disclosure is not particularly limited thereto. Here, the three arbitrary points spaced apart from each other in the first direction may be selected from the extension line (extension surface) of the edge of the capacitance forming portion Ac in which the internal electrode is disposed in the first direction.

[0129] However, the present disclosure is not particularly limited to this, and in order to further generalize the average thickness of each of the first to third plating layers 131b, 132b, 131c, 132c, 131d and 132d, the average thickness can be calculated as the average value of each of the first to third plating layers 131b, 132b, 131c, 132c, 131d and 132d provided on a portion of the first surface 1 and the second surface 2 of the body and / or a portion of the fifth surface and the sixth surface in the first direction and / or the third direction, so that the average thickness of each of the first to third plating layers 131b, 132b, 131c, 132c, 131d and 132d can be generalized.

[0130] The average size of each of the first to third plating layers 131b, 132b, 131c, 132c, 131d, and 132d in the first direction may be, for example, when observing the first and second direction cross-sections of the multilayer electronic component 100 with a scanning electron microscope (SEM), the first direction size of each of the first to third plating layers 131b, 132b, 131c, 132c, 131d, and 132d is measured from three arbitrary points spaced apart from each other in the second direction. The average value is obtained, but the present disclosure is not particularly limited thereto. Here, the three arbitrary points spaced apart from each other in the second direction may refer to points in contact with one surface of the body 110 or points on an extension line of the point, and may be selected from a body region having substantially parallel surfaces rather than a curved edge region.

[0131] Since the average thickness of the first plating layers 131b and 132b satisfies the range of greater than or equal to 5μm and less than or equal to 8μm, external moisture can be effectively prevented from penetrating into the connecting electrode layers 131a-1 and 132a-1 and the strip electrode layers 131a-2 and 132a-2, and the penetration of the plating solution used to form the second plating layers and the third plating layers can be suppressed, and the miniaturization and high capacitance of the multilayer electronic component 100 can be achieved by reducing the thickness of the external electrodes 131 and 132.

[0132] In addition, since the average thickness of the second plating layers 131c and 132c satisfies the range of greater than or equal to 2μm and less than or equal to 4μm, external moisture can be effectively prevented from penetrating into the connecting electrode layers 131a-1 and 132a-1 and the electrode layers 131a-2 and 132a-2, and the penetration of the plating solution used to form the third plating layer can be suppressed.

[0133] In addition, since the average thickness of the third plating layers 131d and 132d satisfies the range of greater than or equal to 2μm and less than or equal to 4μm, external moisture can be effectively prevented from penetrating into the connecting electrode layers 131a-1 and 132a-1 and the strip electrode layers 131a-2 and 132a-2, and when the multilayer electronic component 100 is mounted on a board by plating, the bonding strength with the solder can be excellent.

[0134] The size of the multilayer electronic component 100 does not need to be particularly limited.

[0135] However, in order to achieve both miniaturization and high capacitance, the thickness of the dielectric layer and the internal electrode must be thinned to increase the number of stacks, so that the effect according to the present disclosure can be more significant in a multilayer electronic component 100 having a size of 3216 (length×width: 3.2 mm×1.6 mm) or less.

[0136] Although the exemplary embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the above embodiments and the accompanying drawings, and the scope of the present disclosure is defined by the appended claims. Therefore, those of ordinary skill in the art may make various substitutions, modifications or alterations without departing from the scope of the present disclosure defined by the appended claims, and these substitutions, modifications or alterations should be interpreted as being included within the scope of the present disclosure.

[0137] In addition, the expressions "exemplary embodiments" and "some embodiments" used in the present disclosure do not mean the same embodiment, and are provided to emphasize and explain different unique characteristics. However, the embodiments presented above do not exclude implementation in combination with features of another embodiment. For example, although a matter described in a specific embodiment is not described in another embodiment, unless there is a description in another embodiment that is contrary or contradictory to the matter, the matter can be understood as a description related to another embodiment.

[0138] In the present disclosure, the terms are only used to describe specific embodiments and are not intended to limit the present disclosure. Unless the context clearly indicates otherwise, a singular meaning may also include a plural meaning.

Claims

1. A multilayer electronic component comprising: a body including a dielectric layer and inner electrodes alternately arranged with the dielectric layer in a first direction, and including a first surface and a second surface opposite to each other in the first direction, a third surface and a fourth surface connected to the first surface and the second surface and opposite to each other in the second direction, and a fifth surface and a sixth surface connected to the first surface, the second surface, the third surface and the fourth surface and opposite to each other in the third direction; as well as an outer electrode, disposed on the body, The external electrode includes: a connecting electrode layer, which is arranged on the third surface and the fourth surface and connected to the internal electrode and includes a conductive metal; a strip electrode layer, which contacts the connecting electrode layer, is arranged on a portion of the first surface and the second surface and / or a portion of the fifth surface and the sixth surface and includes a conductive polymer; and a plating layer, which is arranged on the connecting electrode layer and the strip electrode layer, and The conductive metal includes at least one selected from the group consisting of palladium, silver, rhodium, and ruthenium.

2. The multilayer electronic component according to claim 1, wherein The internal electrode includes a diffusion portion, which is a region contacting the connection electrode layer and including the conductive metal.

3. The multilayer electronic component according to claim 2, wherein: The diffusion portion includes an alloy including a main component metal of the inner electrode and the conductive metal.

4. The multilayer electronic component according to claim 2, wherein: The diffusion portion is a region having an average size within 6 μm along an inner direction of the body from a point where the internal electrode and the connection electrode layer contact each other.

5. The multilayer electronic component according to claim 1, wherein The connecting electrode layer does not include glass.

6. The multilayer electronic component according to claim 1, wherein: The conductive polymer includes at least one selected from the group consisting of polypyrrole, polyaniline, polythiophene, and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate.

7. The multilayer electronic component according to claim 1, wherein: The electrode-bearing layer does not include glass.

8. The multilayer electronic component according to claim 1, wherein The outer electrode does not include glass.

9. The multilayer electronic component according to claim 1, wherein: Each of an average thickness of the connection electrode layer in the second direction and an average thickness of the strip electrode layer in the first direction is greater than or equal to 0.1 μm and less than or equal to 4 μm.

10. The multilayer electronic component according to claim 1, wherein The connection electrode layer is not arranged between an extension line of the third surface and an extension line of the fourth surface.

11. The multilayer electronic component according to claim 1, wherein The electrode layer is disposed between an extension line of the third surface and an extension line of the fourth surface.

12. The multilayer electronic component according to claim 1, wherein The plating layer includes a first plating layer including copper.

13. The multilayer electronic component according to claim 1, wherein The plating layer includes: a first plating layer disposed on the connection electrode layer and the strip electrode layer and including copper; a second plating layer disposed on the first plating layer and including nickel; and a third plating layer disposed on the second plating layer and including tin.

14. The multilayer electronic component according to claim 13, wherein: The average thickness of the first plating layer is greater than or equal to 5 μm and less than or equal to 8 μm, and the average thickness of each of the second plating layer and the third plating layer is greater than or equal to 2 μm and less than or equal to 4 μm.

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