Laminated electronic component

Abstract

This laminated electronic component comprises an effective part and a cover. The effective part comprises dielectric layers and internal electrodes which are laminated alternatingly in a lamination direction. The cover overlaps with the effective part in the lamination direction. The cover comprises a plurality of insulating layers laminated in the lamination direction and dummy electrodes positioned between the plurality of insulating layers. The dummy electrodes each have at least one oxidation region.

Description

Multilayer electronic components

[0001] The present disclosure relates to multilayer electronic components such as multilayer ceramic capacitors.

[0002] Multilayer ceramic capacitors are known as multilayer electronic components (see, for example, Patent Document 1 below). A multilayer ceramic capacitor includes, for example, an active portion, a cover, and external electrodes. The active portion includes alternately stacked dielectric layers and flat internal electrodes, and directly functions as a capacitor. The cover covers the active portion in the stacking direction of the dielectric layers and internal electrodes, contributing to the protection of the active portion. The external electrodes are formed by metal layers covering the sides of the main body, which is made up of the active portion and the cover, and contribute to mounting the capacitor on a circuit board, etc. In Patent Document 1, a dummy electrode (auxiliary electrode) is provided on the cover. The dummy electrode contributes to depositing a metal that will become the external electrode, for example, by plating.

[0003] JP 2014-212298 A

[0004] A multilayer electronic component according to one aspect of the present disclosure includes an effective portion and a cover. The effective portion includes dielectric layers and internal electrodes alternately stacked in a stacking direction. The cover overlaps the effective portion in the stacking direction. The cover includes a plurality of insulating layers stacked in the stacking direction and a dummy electrode positioned between the insulating layers. The dummy electrode includes at least one oxidized region.

[0005] Fig. 3 is a perspective view showing a capacitor according to a first embodiment. Fig. 4 is a schematic exploded perspective view of the capacitor of Fig. 1. Fig. 5 is a cross-sectional view taken along line III-III of Fig. 1. Fig. 6 is an enlarged view of region IV of Fig. 3. Fig. 7 is a perspective view showing a capacitor according to a second embodiment.

[0006] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The drawings used in the following description are schematic. Therefore, for example, the dimensional ratios in the drawings do not necessarily correspond to the actual ones. Furthermore, the dimensional ratios may not match between drawings. Certain shapes and / or dimensions may be exaggerated, and details may be omitted. However, the above does not deny that the actual shapes and / or dimensions may be as shown in the drawings, or that features of shapes and / or dimensions may be extracted from the drawings.

[0007] Regarding the embodiments described relatively later, basically, only the differences from the embodiments described relatively earlier will be described. Matters not specifically mentioned may be considered to be the same as the embodiments described earlier or may be inferred from the embodiments described earlier. For convenience, the same reference numerals may be used for corresponding components between different embodiments, even if there are differences.

[0008] In the following description, when referring to a "rectangle" (or rectangular shape), a "square" (or square shape), and a "rectangle" (or rectangular shape), the corners may be chamfered by a curved surface or the like, as long as the concept of the shape is valid. For example, a corner formed by two sides may be chamfered to a length of 1 / 5 or less, 1 / 10 or less, or 1 / 20 or less of the length of the shorter of the two sides. It goes without saying that, when viewed microscopically, the corners may be rounded due to manufacturing precision (errors). The same applies to other polygons, etc.

[0009] (Overview of the Embodiments) Fig. 1 is a perspective view showing a capacitor 1 (an example of a multilayer electronic component) according to a first embodiment. For convenience, Fig. 1 and other figures described below are illustrated with a Cartesian coordinate system D1D2D3. The capacitor 1 may be used with either side designated as upper or lower. However, in the description of the embodiments, for convenience, the +D3 side may be designated as upper, and terms such as upper surface and lower surface may be used.

[0010] The capacitor 1 is, for example, a multilayer ceramic capacitor. The capacitor 1 has a roughly rectangular parallelepiped body 3 and four external electrodes 5 located at the four corners of the body 3 in a plan view (as viewed in the direction D3). The external electrodes 5 contribute to electrical connection between the capacitor 1 and other electronic components (for example, a circuit board (not shown)).

[0011] Fig. 3 is a cross-sectional view taken along line III-III in Fig. 1. Fig. 3 shows a D1D3 cross-section taken through the external electrode 5 on the +D2 side. However, the D1D3 cross-section taken through the external electrode 5 on the -D2 side, the D2D3 cross-section taken through the external electrode 5 on the -D1 side, and the D2D3 cross-section taken through the external electrode 5 on the +D1 side are basically the same. In explaining the embodiments, for convenience, the positional relationships between components may be explained using the terms D1, D2, and D3 without any particular mention, assuming the cross-section shown in Fig. 3.

[0012] The main body 3 has, for example, an active portion 11, two covers 13 respectively overlapping the upper and lower surfaces of the active portion 11, and an underlayer 15 overlapping the surface of each cover 13 opposite the active portion 11. The active portion 11 has a plurality of alternating dielectric layers 7 and a plurality of internal electrodes 9. The multiple internal electrodes 9 include a plurality of first internal electrodes 9A and a plurality of second internal electrodes 9B. Each underlayer 15 has, for example, four underlayer electrodes 16 at positions corresponding to the positions of the four external electrodes 5.

[0013] The active portion 11 directly functions as a capacitor. The cover 13 contributes, for example, to protecting and strengthening the main body portion 3. The base electrode 16 contributes, for example, to depositing a metal that will become the external electrode 5 by plating and / or improving the adhesive strength of the external electrode 5 to the main body portion 3.

[0014] Each cover 13 has, for example, a plurality of insulating layers 17 (two in the example of FIG. 3 ) and at least one dummy layer 19 (one in the example of FIG. 3 ) located between the plurality of insulating layers 17. Each dummy layer 19 has, for example, four dummy electrodes 20 at positions corresponding to the positions of the four external electrodes 5. The dummy electrodes 20 contribute to, for example, reinforcing the cover 13 and / or improving the connection strength between the main body 3 and the external electrodes 5, and also function as a base for the external electrodes 5 in an embodiment in which the external electrodes 5 are formed by plating.

[0015] Fig. 4 is an enlarged view of region IV in Fig. 3. The dummy electrode 20 has at least one oxidized region 20x (three in Fig. 4).

[0016] The formation of the oxidized region 20x increases, for example, the volume of the dummy electrode 20. As a result, for example, the adhesion between the dummy electrode 20 and the insulating layer 17 is improved. In other words, the likelihood of a gap being formed between them is reduced. The improved adhesion improves, for example, the strength of the cover 13. In addition, for example, the likelihood that gas and / or liquid that has entered the gap for some reason will affect the mechanical and / or electrical properties is reduced. In an embodiment in which the external electrode 5 is formed by plating, the likelihood that a plating solution will enter the gap and affect the mechanical and / or electrical properties is reduced.

[0017] The above is an overview of the embodiments. Specifically, the embodiments will be described roughly in the following order: 1. Structure of the capacitor according to the first embodiment (FIGS. 1 to 3) 1.1. Overall structure 1.2. Effective portion 1.3. Cover 1.4. Base electrode 1.5. External electrode 2. Oxidized region 2.1. Oxidized region of dummy electrode 2.2. Comparison with oxidized regions of other electrodes 3. Method of manufacturing a capacitor 4. Structure of a capacitor according to another embodiment (FIG. 6) 5. Summary of the embodiment

[0018] (1. Configuration of the Capacitor According to the First Embodiment) (1.1. Overall Configuration) The capacitor 1 shown in FIG. 1 is configured, for example, as a surface-mounted chip component. Specifically, for example, the capacitor 1 is placed with the −D3 side or +D3 side facing a circuit board (not shown). Then, the four pads on the circuit board and the four external electrodes 5 are respectively joined with a conductive bonding material (for example, solder) (not shown), thereby mounting the capacitor on the circuit board.

[0019] The configuration (internal structure and external shape) of the capacitor 1 is, for example, approximately plane-symmetric with respect to a plane of symmetry (not shown) that is parallel to the D1D2 plane and passes through the center of the thickness direction (D3 direction) of the capacitor 1. Furthermore, the configuration of the capacitor 1 is, for example, rotationally symmetric by 180° when viewed in the D3 direction. Of course, the capacitor 1 does not have to have such symmetry.

[0020] The shape of the main body 3 is, for example, a generally thin rectangular parallelepiped. This rectangular parallelepiped may be square (as in the illustrated example) or rectangular (excluding squares; the same applies below) in plan view. For convenience, in the description of the embodiments, a square shape may be assumed unless otherwise specified.

[0021] The specific dimensions of the main body 3 (or capacitor 1) are arbitrary. To give an example of dimensions when the capacitor 1 is relatively small, the lengths of the main body 3 (or capacitor 1) in the D1 and D2 directions may each be 0.030 mm or more and 0.200 mm or less. When the length in the D1 direction is L and the length in the D2 direction is W, L / W may be 0.5 or more and 2.0 or less. The thickness in the D3 direction may be 0.030 mm or more and 0.200 mm or less. When the surface of the main body 3 is not flat, for example, the maximum values ​​of the various dimensions may satisfy the above ranges (the same applies hereinafter to the various dimensions of other components unless a contradiction arises).

[0022] Unless otherwise specified, the examples of dimensions of each component described below are for a relatively small capacitor 1. Therefore, dimensions larger (or smaller) than the illustrated dimensions may be used.

[0023] A plurality of components of the same type (e.g., 5, 7, 9, 13, 15, 16, 17, 19, or 20, etc.) may basically (except for relatively small differences, for example; the same applies hereinafter) be provided with the same (or corresponding) shape, size, material, position, etc. unless otherwise specified or unless a contradiction occurs. Therefore, unless otherwise specified or unless a contradiction occurs, a description of one component may be considered to be common to a plurality of components of the same type.

[0024] A layer (film) of a component (e.g., 5, 7, 9, 15, 17, or 19) may be entirely made of a single material, but may also be made of layers of different materials stacked on top of each other.

[0025] (1.2. Effective Portion) The shape of the effective portion 11 shown in FIG. 3 is, for example, a generally thin rectangular parallelepiped. Its planar shape is basically the same as that of the main body portion 3. The specific thickness of the effective portion 11 is arbitrary. For example, the thickness of the effective portion 11 may be 30% or more, 40% or more, or 50% or more of the thickness of the main body portion 3, and may be 90% or less, 80% or less, or 70% or less. The above lower and upper limits may be combined arbitrarily. The thickness of the main body portion 3 is, for example, the thickness from the upper surface of the upper base electrode 16 to the lower surface of the lower base electrode 16. The thickness of the effective portion 11 is, for example, the thickness from the upper surface of the uppermost internal electrode 9 to the lower surface of the lowermost internal electrode 9.

[0026] The dielectric layer 7 is essentially a layer having a constant thickness (at least between the internal electrodes 9). The thickness of the dielectric layer 7 may be appropriately set depending on the characteristics required of the capacitor 1. Examples of relatively thin thicknesses include a thickness between adjacent internal electrodes 9 (between the first internal electrode 9A and the second internal electrode 9B) of 0.1 μm or more or 0.5 μm or more, and a thickness of 3.0 μm or less, 2.0 μm or less, or 1.0 μm or less. The above lower and upper limits may be combined arbitrarily. The shape and dimensions of the dielectric layer 7 in a planar view are basically the same as those of the active portion 11 in a planar view. The material of the dielectric layer is, for example, ceramic, and the specific type is also arbitrary. The number of laminated dielectric layers 7 (internal electrodes 9) is arbitrary. For example, the number may be 10 to 30.

[0027] The internal electrode 9 is a layer having a constant thickness. The thickness of the internal electrode 9 is arbitrary, and may be thinner, the same as, or thicker than the thickness of the region of the dielectric layer 7 between the internal electrodes 9. Examples of relatively thin thicknesses include the thickness of the internal electrode 9 being 0.3 μm or more or 0.5 μm or more, and 3.0 μm or less, 2.0 μm or less, or 1.0 μm or less. The above lower and upper limits may be combined arbitrarily. The material of the internal electrode 9 is, for example, a metal. The specific type of metal is arbitrary, and for example, the entire or main component (e.g., 60 mass% or more of a component; the same applies hereinafter) is a base metal (e.g., Ni and / or Cu).

[0028] Fig. 2 is an exploded perspective view of the capacitor 1. Fig. 2 is a schematic diagram for understanding the shapes and relative positions of the internal electrodes 9, etc. Therefore, Fig. 2 shows a smaller number of various layers than Fig. 3.

[0029] The internal electrode 9 has, for example, a rectangular (square in the illustrated example) electrode body 9a in a plan view and a pair of lead electrodes 9b extending from a pair of opposing corners of the electrode body 9a. The internal electrode 9 is located inside the outer edge of the dielectric layer 7 and is not exposed from the side surface of the effective portion 11. The pair of lead electrodes 9b reach the outer edge of the dielectric layer 7 and are connected to a pair of external electrodes 5 located at a pair of opposing corners of the main body portion 3.

[0030] The first internal electrode 9A and the second internal electrode 9B face each other across the dielectric layer 7. A pair of lead electrodes 9b of the first internal electrode 9A and a pair of lead electrodes 9b of the second internal electrode 9B are located on different diagonal lines in a planar perspective view, and are connected to different pairs of external electrodes 5.

[0031] The electrode body 9a and the lead electrode 9b may have any dimensions. For example, the length of the lead electrode 9b on one side of the dielectric layer 7 is approximately the same as the length of the external electrode 5 along the same side.

[0032] (1.3. Cover) The cover 13 shown in FIG. 3 is, for example, a layer having a shape and dimensions that overlap the effective portion 11 without excess or deficiency. The thickness of the cover 13 is approximately constant in both the region where the base electrode 16 is disposed and the region where the base electrode 16 is not disposed. The ratio of the thickness of the cover 13 to the thickness of the main body portion 3 may be approximately the reverse of the ratio of the thickness of the effective portion 11 to the thickness of the main body portion 3 (as described above). For example, in an embodiment in which covers 13 are provided on both sides in the D3 direction, the thickness of one cover 13 may be, for example, 5% or more, 10% or more, or 15% or more of the thickness of the main body portion 3, or 35% or less, 30% or less, or 25% or less. The above lower and upper limits may be arbitrarily combined. The thickness of the cover 13 is, for example, the thickness in the region that overlaps the internal electrode 9 but does not overlap the base electrode 16 (i.e., the region that is not crushed by the base electrode 16).

[0033] The insulating layers 17 and the dummy layers 19 are alternately stacked one on top of the other. In other words, the dummy layers 19 are provided at the boundaries of all the insulating layers 17. Unlike the illustrated example, the dummy layers 19 may be provided only at some of the boundaries. For example, the dummy layers 19 may not be provided at one or more boundaries relatively close to the effective portion 11, and the dummy layers 19 may be provided only at one or more boundaries relatively far from the effective portion 11. However, in such a case, two or more insulating layers 17 that are in close contact with each other without a dummy layer 19 interposed therebetween may be regarded as a single insulating layer 17.

[0034] The insulating layer 17 is a layer having a substantially constant thickness, excluding variations in thickness resulting from the presence or absence of overlap with the conductor layers (9, 15, and 19). The planar shape of the insulating layer 17 is, for example, basically the same as the planar shape of the dielectric layer 7. The material of the insulating layer 17 is arbitrary. For example, the material of the insulating layer 17 may be the same as or different from the material of the dielectric layer 7. Furthermore, the material of the insulating layer 17 may be, for example, ceramics or a material other than ceramics.

[0035] The thickness of the insulating layer 17 is arbitrary. For example, the thickness of the insulating layer 17 may be thicker (in the illustrated example), equal to, or thinner than the thickness of the dielectric layer 7 (both of which are thicknesses between conductor layers or thicknesses of regions not overlapping conductor layers; the same applies hereinafter in this paragraph). For example, the thickness of the insulating layer 17 may be two or more, three or more, or five or more times the thickness of the dielectric layer 7, and may be 20 or less, 10 or less, or 5 or less times the thickness of the dielectric layer 7. The above lower and upper limits may be combined in any combination. For example, the thickness of the insulating layer 17 may be 1.0 μm or more or 2.0 μm or more, and may be 10.0 μm or less or 5.0 μm or less. The above lower and upper limits may be combined in any combination. Note that an insulating layer overlapping the uppermost internal electrode 9 may be considered to be the insulating layer 17, not the dielectric layer 7, regardless of its material and thickness. The same applies to an insulating layer overlapping the lowermost internal electrode 9.

[0036] The dummy electrode 20 is, for example, a layer having a substantially constant thickness. The material of the dummy electrode 20 is, for example, a metal. The specific type of metal is arbitrary, and for example, the entire or main component thereof is a base metal (e.g., Ni and / or Cu). The material of the dummy electrode 20 may be the same as or different from the material of the internal electrode 9. The position, shape, and size of the dummy electrode 20 are arbitrary in plan view. In the examples of FIGS. 2 and 3 , the position, shape, and size of the dummy electrode 20 are such that, in plan perspective, they overlap approximately exactly with the external electrode 5 (however, the external electrode 5 is slightly wider). The dummy electrode 20 is exposed, for example, on the side surface of the main body 3. This exposed portion is fixed to the external electrode 5.

[0037] The thickness of the dummy electrode 20 is arbitrary. For example, the thickness of the dummy electrode 20 may be thicker than, equal to, or thinner than the thickness of the internal electrode 9 (as in the illustrated example). For example, the thickness of the dummy electrode 20 may be 1 time or more, 1.5 times or more, or 2 times or more, or 10 times or less, 5 times or less, or 2 times or less, of the thickness of the internal electrode 9. The above lower and upper limits may be combined in any combination. For example, the thickness of the dummy electrode 20 may be 0.3 μm or more, 0.5 μm or more, 1.0 μm or more, or 2.0 μm or more, or 10.0 μm or less, 5.0 μm or less, 3.0 μm or less, or 2.0 μm or less. The above lower and upper limits may be combined in any combination. The thickness of the dummy electrode 20 may be thinner than, equal to, or thicker than the thickness of the insulating layer 17 (as in the illustrated example).

[0038] (1.4. Base Electrode) The base electrode 16 is, for example, a layer having a substantially constant thickness. The material of the base electrode 16 is, for example, a metal. The specific type of metal is arbitrary, and for example, the entire or main component thereof is a base metal (e.g., Ni and / or Cu). The material of the base electrode 16 may be the same as or different from the material of the internal electrode 9 and / or the material of the dummy electrode 20. In a plan view, the position, shape, and size of the base electrode 16 are arbitrary. In the examples of Figures 2 and 3, the position, shape, and size of the base electrode 16 are such that, in a planar perspective view, they approximately overlap with the external electrode 5 without excess or deficiency (however, the external electrode 5 is slightly wider).

[0039] The thickness of the base electrode 16 is arbitrary. For example, the thickness of the base electrode 16 may be thicker than, equal to, or thinner than the thickness of the internal electrode 9 and / or the dummy electrode 20 (as in the illustrated example). For example, the thickness of the base electrode 16 may be two or more times, three or more times, or five or more times the thickness of the internal electrode 9 and / or the dummy electrode 20, and may be 20 or less times, 10 or less times, or 5 or less times the thickness of the internal electrode 9 and / or the dummy electrode 20. The above lower and upper limits may be combined in any combination. For example, the thickness of the base electrode 16 may be 2.0 μm or more, 3.0 μm or more, or 5.0 μm or more, and may be 20.0 μm or less, 10.0 μm or less, or 5.0 μm or less. The above lower and upper limits may be combined in any combination. The thickness of the base electrode 16 may be thinner, equal to, or thicker than the thickness of the insulating layer 17 (as in the illustrated example).

[0040] (1.5. External Electrode) The external electrode 5 is, for example, a layer having a substantially constant thickness. The material of the external electrode 5 is, for example, a metal. The specific type of metal is arbitrary, and for example, the entire or main component thereof is a base metal (for example, Ni and / or Cu). Furthermore, the external electrode 5 may be formed by laminating different materials as necessary. For example, the external electrode 5 may be formed by laminating Cu, Ni, and Sn from the side of the base electrode 16. The material of the external electrode 5 may be the same as or different from the material of the internal electrode 9, the material of the dummy electrode 20, and / or the material of the base electrode 16.

[0041] As shown in FIG. 1 , the external electrodes 5 cover the four surfaces (top, bottom, and two side surfaces) of the main body 3, for example, roughly at the corners of the main body 3 in a plan view. This allows one external electrode 5 to be connected to one extraction electrode 9b on two side surfaces of the main body 3, and also makes it possible to surface mount the capacitor 1 on either the top or bottom surface. The shape and dimensions of the portions of the external electrodes 5 on each surface are arbitrary. The planar shape of the portion of the external electrode 5 located on the top or bottom surface of the main body 3 is, for example, rectangular (square in the illustrated example). Furthermore, the planar shape and dimensions of the portion of the external electrode 5 located on the side surface of the main body 3 are, for example, rectangular with the same horizontal length as the portion located on the top or bottom surface.

[0042] The thickness of the external electrode 5 is arbitrary. For example, the thickness of the external electrode 5 may be thicker than the thicknesses of the internal electrode 9, the dummy electrode 20, and the base electrode 16. For example, the thickness of the external electrode 5 may be 1.2 times or more, 2 times or more, or 3 times or more the thickness of the base electrode 16, or 10 times or less, 5 times or less, or 3 times or less. The above lower limit and upper limit may be combined arbitrarily. Furthermore, for example, the thickness of the external electrode 5 may be 3 μm or more, 5 μm or more, or 10 μm or more, or 30 μm or less, 20 μm or less, or 10 μm or less. The above lower limit and upper limit may be combined arbitrarily.

[0043] (2. Oxidized Region) (2.1. Oxidized Region of Dummy Electrode) In the oxidized region 20x ( FIG. 4 ), the metal contained in the dummy electrode 20 is oxidized. That is, the oxidized region 20x is configured to contain a metal oxide. The specific type of metal oxide is arbitrary. For example, when the entire or main component of the dummy electrode 20 (before oxidation) is Ni, the oxidized region 20x contains NiO.

[0044] The oxidized region 20x can be observed, for example, by a scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). Specifically, when observed with an SEM at an appropriate magnification, the oxidized region 20x is observed as a region (hereinafter referred to as a different hue region) that exhibits a different hue from the region of the dummy electrode 20 other than the oxidized region 20x. Furthermore, if the presence of elements that are the main components of the dummy electrode 20 and oxygen elements is confirmed by EDS in the spot where the different hue region identified by SEM is located, the different hue region can be said to be the oxidized region 20x in which the dummy electrode 20 is oxidized. Note that by identifying the range of the different hue region with an SEM, the range of the oxidized region 20x can be identified and the dimensions of the range can be measured.

[0045] Methods for confirming the presence of oxygen elements using EDS include, for example, point analysis and mapping analysis. For example, point analysis may be used to confirm the presence of oxygen elements in the different hue regions by confirming the spectrum of oxygen elements from the spots where the different hue regions are located. Alternatively, mapping analysis may be used to confirm that the oxygen element concentration in the spots where the different hue regions are located is higher than the oxygen element concentration in regions other than the different hue regions on the dummy electrode 20. This is because it is unreasonable to consider the oxidized region 20x to be publicly known based on the unavoidable and extremely small amount of oxygen present in known technology.

[0046] The above-described point analysis or mapping analysis can be used as a method for confirming the presence of the element that is the main component of the dummy electrode 20. In this paragraph, Ni will be described as an example of the element that is the main component of the dummy electrode 20. For example, the presence of Ni element in the different hue region may be confirmed by confirming the spectrum of Ni element from the spot where the different hue region is located using point analysis. Furthermore, the presence of Ni element in the different hue region may be confirmed by confirming, for example, using mapping analysis, that the Ni element concentration in the spot where the different hue region is located is higher than the Ni element concentration in the insulating layer 17.

[0047] In the above mapping analysis, the area for calculating the concentration of oxygen elements may be set appropriately. For example, the oxygen concentration may be calculated for each predetermined unit area in a cross section parallel to the D3 direction (e.g., a D1D3 cross section) as shown in FIG. 4 . The unit area may be set to an appropriate size. For example, the unit area may be 0.01 μm ２ (or an even smaller area). Note that the unit area may be larger (i.e., the accuracy may be lower) depending on the situation. The shape of each unit area may be, for example, a square (e.g., a 0.1 μm×0.1 μm square).

[0048] As an SEM-EDS analysis device for observing the oxidized region 20x, for example, JSM-6010LV manufactured by JEOL Ltd. can be used.

[0049] In a cross section parallel to the D3 direction as shown in FIG. 4 (for example, a D1D3 cross section), the number, distribution pattern, area ratio (volume ratio), size, shape, etc. of the oxidized regions 20x of one dummy electrode 20 are arbitrary.

[0050] For example, the dummy electrode 20 may have multiple oxidized regions 20x (as in the illustrated example), the entire dummy electrode 20 may be an oxidized region 20x, or the dummy electrode 20 may have one oxidized region 20x as a partial region. The multiple oxidized regions 20x may be distributed in the D1 direction, as in the illustrated example. And / or the multiple oxidized regions 20x may include, for example, a layered oxidized region 20x that forms the upper surface of the dummy electrode 20 and a layered oxidized region 20x that forms the lower surface of the dummy electrode 20. The single oxidized region 20x that forms a partial region of the dummy electrode 20 may be, for example, a partial region in the D1 direction, as in the illustrated example, or may be a partial region that forms the upper or lower surface of the dummy electrode 20.

[0051] Furthermore, for example, in an aspect in which one or more oxidized regions 20x are formed as part of the dummy electrode 20, the proportion of the total area of ​​the oxidized regions 20x to the area of ​​the dummy electrode 20 is arbitrary. For example, the proportion may be 3% or more, 5% or more, 7% or more, 10% or more, 50% or more, or 80% or more, or 80% or less, 50% or less, 20% or less, 15% or less, or 10% or less. The above lower limit and upper limit may be arbitrarily combined as long as no contradiction occurs.

[0052] For example, when the ratio of the total area of ​​the oxidized regions 20x to the area of ​​the dummy electrode 20 is 3% or more, the increase in the volume of the oxidized regions 20x improves the adhesion between the dummy electrode 20 and the insulating layer 17, significantly reducing the penetration of plating liquid. On the other hand, when the total area of ​​the oxidized regions 20x relative to the area of ​​the dummy electrode 20 becomes excessively large, the increased volume increases the risk of stress being applied inside the capacitor, increasing the likelihood of cracks occurring. For example, when the ratio of the total area of ​​the oxidized regions 20x to the area of ​​the dummy electrode 20 is 20% or less, the excessive increase in the volume of the dummy electrode 20 can be reduced, thereby reducing the likelihood of cracks occurring.

[0053] Furthermore, for example, in a configuration in which one or more oxidized regions 20x are formed as part of the dummy electrode 20, the oxidized regions 20x may be uniformly or non-uniformly distributed across the dummy electrode 20. An example of the latter is given below. The dummy electrode 20 is divided into a region on the −D1 side and a region on the +D1 side, with the center in the D1 direction (see the center line CL) as the boundary. In FIG. 4 , the −D1 side is the end side of the cover 13, and the +D1 side is the central side of the cover 13. In this case, for example, the total area of ​​the oxidized regions 20x in the −D1 side region may be larger than the total area of ​​the oxidized regions 20x in the +D1 side region. In other words, the area ratio of the oxidized regions 20x on the end side of the cover 13 may be higher than that on the central side of the cover 13. In this case, the difference between the areas (or ratios) of the two regions may be arbitrary. For example, the area of ​​the former may be 1.2 times or more or 2 times or more the area of ​​the latter.

[0054] Furthermore, for example, in an embodiment in which one or more oxidized regions 20x are formed as part of the dummy electrode 20, as can be understood from the above description, each oxidized region 20x may extend across the entire thickness of the dummy electrode 20 (as in the illustrated example), or may occupy only a portion of the thickness. In the latter embodiment, the oxidized region 20x is not limited to the layered shape already mentioned, but may also be in a block shape. Furthermore, the specific size of the diameter of the oxidized region 20x in the D3 direction is also arbitrary. For example, the diameter of the oxidized region 20x in the D3 direction (or the maximum length in the D3 direction) may be greater than or equal to half the thickness of the dummy electrode 20.

[0055] Furthermore, for example, in an embodiment in which one or more oxidized regions 20x are formed as part of the dummy electrode 20, as can be understood from the above description, the diameter in the D1 direction of each oxidized region 20x may also be arbitrary. For example, the diameter in the D1 direction of each oxidized region 20x (or the maximum length in the D1 direction) may be equal to or greater than half the length in the D1 direction of the dummy electrode 20. Furthermore, the diameter in the D1 direction of each oxidized region 20x (or the maximum length in the D1 direction) may be equal to or greater than half the thickness of the dummy electrode 20.

[0056] Furthermore, for example, in a configuration in which one or more oxidized regions 20x are formed as part of the dummy electrode 20, as can be understood from the above description, the aspect ratio of each oxidized region 20x is arbitrary. For example, the diameter in the D1 direction (or the maximum length in the D1 direction) may be equal to or greater than half the diameter in the D3 direction (or the maximum length in the D3 direction). The shape of the oxidized region 20x is also arbitrary, and may be, for example, a circle, an ellipse, an oval (as in the illustrated example), or a rectangle.

[0057] Furthermore, as can be understood from the above description, the diameter (minimum diameter, maximum diameter, circle-equivalent diameter, etc.) of the oxidized region 20x is arbitrary. Note that the diameter is the distance across the geometric center (centroid) of the oxidized region 20x. For example, the minimum diameter of the oxidized region 20x may be 0.5 μm or more, 1.0 μm or more, or 2.0 μm or more. Furthermore, the minimum diameter may be the same as the thickness of the dummy electrode 20 and may or may not be the diameter in the D3 direction.

[0058] Focus on one dummy electrode 20. The dummy electrode 20 has a length in the D2 direction. Therefore, there are an infinite number of D1D3 cross sections such as those shown in FIG. 4 in the D2 direction. When the configuration (oxygen concentration, distribution pattern, area ratio, size and / or shape, etc.) of the oxidized region 20x in the D1D3 cross section described above is said to be valid, it is not necessary that the configuration of the oxidized region 20x be valid in all cross sections. For example, the configuration may be valid over one-third or more, one-half or more, or two-thirds or more of the length of the dummy electrode 20 in the D2 direction. Of course, the configuration may be valid over the entire length of the dummy electrode 20 in the D2 direction.

[0059] Whether or not the configuration related to the oxidized region 20x is valid within the above-described length range may be determined, for example, based on a predetermined number (e.g., 3, 5, or 10) of D1D3 cross-sectional images set at equal distances along the length of the dummy electrode 20 in the D2 direction. If it is difficult to extract multiple cross-sectional images from one capacitor 1, multiple cross-sectional images may be extracted from multiple capacitors 1 of the same type.

[0060] In the examples of FIGS. 1 to 3, a plurality of dummy electrodes 20 are provided. The above-described configuration related to the oxidized region 20x does not need to be true for all of the plurality of dummy electrodes 20. For example, in an embodiment in which one cover 13 has a plurality of dummy layers 19, only the dummy layer 19 close to the effective portion 11 or the dummy layer 19 far from the effective portion 11 may have the above-described configuration related to the oxidized region 20x. Furthermore, for each dummy electrode 20, the above-described configuration related to the oxidized region 20x may be true in both the D1 direction and the D2 direction, but it is not necessary for the above-described configuration to be true in both directions. Of course, the above-described configuration related to the oxidized region 20x may be true for all dummy electrodes 20 and in all directions.

[0061] (2.2. Comparison with Oxidized Regions of Other Electrodes) The presence or absence of oxidized regions in the other electrodes (internal electrode 9, base electrode 16, and external electrode 5), and the specific form of the oxidized regions if they exist, are arbitrary. The above description of the oxidized region 20x (concentration threshold, distribution pattern, area ratio, size, shape, etc.) may be applied to other electrodes as long as no contradictions arise.

[0062] Also, for example, in the same cross section, the area ratio of the oxidized region 20x in the dummy electrode 20 may be larger, equal to, or smaller than the area ratio of the oxidized region in the other electrodes.

[0063] Note that, like the configuration related to the oxidized region 20x, the example described below does not need to be true for all dummy electrodes 20 (or other electrodes), and does not need to be true for all of the countless D1D3 cross sections that exist in the D2 direction. In this regard, the above-mentioned explanation related to the oxidized region 20x may also be used.

[0064] The region of the internal electrode 9 where the metal is oxidized is referred to as the oxidized region 9x. The ratio of the total area of ​​all the oxidized regions 20x to the area of ​​the dummy electrode 20 (hereinafter referred to as the "first ratio") may be greater than the ratio of the total area of ​​all the oxidized regions 9x to the area of ​​the internal electrode 9 (hereinafter referred to as the "second ratio"). In this regard, the internal electrode 9 may or may not have an oxidized region 9x. When an oxidized region 9x exists, the difference between the first ratio and the second ratio may be any value. For example, the first ratio may be 1.2 times or more, or 2 times or more, the second ratio.

[0065] The above description of the comparison between the dummy electrode 20 and the internal electrode 9 may be applied to the base electrode 16 by substituting the term internal electrode 9 for the term base electrode 16. FIG. 4 illustrates an example in which no oxidized region exists in the base electrode 16.

[0066] Furthermore, the above description of the comparison between the dummy electrode 20 and the internal electrode 9 may be applied to the external electrode 5 by replacing the term internal electrode 9 with the term external electrode 5. Fig. 4 illustrates an example in which no oxidized region exists in the external electrode 5. Furthermore, in the case where the external electrode 5 includes a plurality of metal layers, the above description of the comparison between the dummy electrode 20 and the internal electrode 9 may be applied to some of the plurality of metal layers.

[0067] (3. Method for Manufacturing Capacitor) The capacitor 1 may be manufactured by various methods. For example, the general procedure may be the same as a known procedure. An example is shown below.

[0068] First, ceramic green sheets that will become the dielectric layers 7 and insulating layers 17 are prepared. Next, a conductive paste that will become the internal electrodes 9, dummy electrodes 20, or base electrodes 16 is applied (e.g., printed) to the ceramic green sheets. Next, the ceramic green sheets are stacked to prepare a laminate that will become the main body portion 3. Note that the stacking of the laminate that will become the active portion 11 and the stacking of the portion that will become the cover 13 on the laminate may be performed together or separately.

[0069] The process up to the production of the laminate is carried out, for example, on a mother substrate the size of which will be used to produce a large number of main body portions 3. After the laminate is produced, the mother substrate including the laminate is diced (e.g., cut) into pieces each having a size roughly corresponding to the size of the main body portion 3. Next, the laminate having the size of the main body portion 3 is fired. After that, a metal film is formed on the main body portion 3, and the external electrodes 5 are formed.

[0070] Degreasing may be performed before firing. Firing may be performed, for example, in a reducing atmosphere. Re-oxidation heat treatment may be performed after firing. Polishing (e.g., barrel polishing) of the main body portion 3 may be performed before and / or after firing. In polishing, for example, the ridges of the main body portion 3 may be chamfered or the side surfaces of the main body portion 3 may be polished.

[0071] The external electrode 5 may be formed by various methods. For example, metal may be deposited on the surface of the base electrode 16 and on the exposed edges of the internal electrode 9 and dummy electrode 20 by electroless plating and / or electrolytic plating. Alternatively, a thin film formation method such as a dipping method, a printing method, CVD (Chemical Vapor Deposition), or PVD (Physical Vapor Deposition) may be employed. As understood from the above, the base electrode 16 and the dummy electrode 20 may or may not contribute to the deposition of metal.

[0072] The method for forming the oxidized region 20x (and other oxidized regions) and the method for adjusting the area ratio, etc. are arbitrary. For example, the degree of oxidation of the internal electrode 9 and the dummy electrode 20 may be adjusted by adjusting the amount of oxygen contained in the conductive paste before application and / or adjusting the time for which the ceramic green sheets coated with the conductive paste before lamination are exposed to an oxidizing atmosphere. Furthermore, for example, an oxidizing agent or a reducing agent may be used at an appropriate time. By making the entire or part of the dummy electrode 20 thicker than a certain level, the dummy electrode 20 may be more easily exposed to oxygen during or after firing, thereby increasing the degree of oxidation absolutely or relatively to that of the internal electrode 9. The same method may be used for the base electrode 16. Furthermore, since the base electrode 16 is exposed to the outside before the formation of the external electrode 5, the degree of oxidation may be adjusted after firing using an oxygen atmosphere, an oxidizing agent, or a reducing agent.

[0073] 5 is a perspective view of a capacitor 201 according to a second embodiment. FIGS. 3 and 4 according to the first embodiment may be referred to as cross-sectional views of the capacitor 201.

[0074] Generally speaking, the capacitor 201 is a two-terminal type, which differs from the four-terminal type capacitor 1. In the capacitor 201, an oxidized region 20x may be formed on the dummy electrode 20, as described with reference to FIGS.

[0075] The specific shapes and dimensions of the components of capacitor 201 may differ from those of capacitor 1, since capacitor 201 is a two-terminal type. Specifically, they are as follows.

[0076] The shape of the main body 203 (or the capacitor 201) is, for example, a roughly rectangular parallelepiped. For example, the height (length in the D3 direction) of this rectangular parallelepiped may be equal to or smaller than the width (length in the D2 direction) (as in the illustrated example). The length (D1 direction) of the rectangular parallelepiped is, for example, greater than the width. The dimensions of the main body 203 are arbitrary. As long as the length in the D1 direction is longer than the length in the D2 direction, the specific examples of the dimensions of the main body 3 in the first embodiment may be applied to the dimensions of the main body 203. The external electrode 5 is generally layer-like, covering the longitudinal ends of the main body 203 over five faces of the rectangular parallelepiped.

[0077] The planar shape of the internal electrode 9 is, for example, approximately a rectangle having four sides parallel to the four sides of the rectangular main body 203 (dielectric layer 7). Of the four sides of the internal electrode 9, two long sides and one short side are, for example, located inside the side surface of the main body 203 (not exposed). The remaining short side is exposed from the side surface on the +D1 side or the -D1 side of the main body 203. The region of the internal electrode 9 that overlaps with other internal electrodes 9 in a planar perspective view is the electrode main body 9a. The portion extending from the electrode main body 9a to the external electrode 5 is the extraction electrode 9b.

[0078] Each dummy layer 19 has, for example, two dummy electrodes 20 at both ends in the longitudinal direction of the main body portion 203. The planar shape of the dummy electrode 20 is, for example, a rectangle spanning the entire width (length in the D2 direction) of the main body portion 203, and is exposed, for example, from the side surface on the +D1 side or the −D1 side of the main body portion 203 and from the side surface on the +D2 side and the −D2 side. The above description of the configuration of the dummy layer 19 (dummy electrode 20) in a planar view may be applied to the configuration of the base layer 15 (base electrode 16) in a planar view.

[0079] Although not specifically shown, another example of the capacitor configuration will be given below.

[0080] The capacitor may have an exterior resin that covers the entire structure illustrated in Fig. 1 or 5, and lead wires that are connected to the external electrodes 5 and extend from the exterior resin. From another perspective, the capacitor may be a through-hole mount type rather than a surface mount type. In such an embodiment, one external electrode 5 may cover only one side surface.

[0081] Two types of internal electrodes 9 connected to different external electrodes 5 may be alternately stacked two by two, rather than one by one. In this case, for example, the thickness of the dielectric layer 7 between the mutually opposing internal electrodes 9 connected to the same external electrode 5 may be thinner than the thickness of the dielectric layer 7 between the mutually opposing internal electrodes 9 connected to different external electrodes 5. As can be understood from this, the multiple dielectric layers 7 do not need to have the same shape and size.

[0082] Furthermore, two types of internal electrodes 9 connected to different external electrodes 5 do not have to face each other. For example, two types of internal electrodes 9 connected to different external electrodes 5 may be provided in the same layer, and an internal electrode 9 facing the two types of internal electrodes 9 may be provided, thereby forming a circuit in which two parallel plate capacitors are connected in series. Also, a circuit in which three or more parallel plate capacitors are connected in series may be formed.

[0083] In the example of Figure 5, the edge of the internal electrode 9, for example, a portion other than the -D1 side or the +D1 side (referred to in this paragraph as the "non-exposed edge portion") is not exposed from the side surface of the main body portion 203. This non-exposed edge portion is covered by the portions of the dielectric layer 7 and the insulating layer 17 that extend outward beyond the non-exposed edge portion. However, the non-exposed edge portion may be covered by overlapping another dielectric layer on the side surface of the laminate formed by the dielectric layer 7 and the insulating layer 17, thereby preventing it from being exposed. From another perspective, the main body portion 203 does not need to have a laminated structure in its entirety.

[0084] (5. Summary of the Embodiments) In the following description, for convenience, the reference numerals of the first embodiment will be used, but the matters described below also apply to the other embodiments unless a contradiction arises.

[0085] The multilayer electronic component (capacitor 1) has an active portion 11 and a cover 13. The active portion 11 has dielectric layers 7 and internal electrodes 9 alternately stacked in a stacking direction (direction D3). The cover 13 overlaps the active portion 11 in the direction D3. The cover 13 has a plurality of insulating layers 17 stacked in the direction D3, and a dummy electrode 20 located between the plurality of insulating layers 17. The dummy electrode 20 has at least one oxidized region 20x.

[0086] Therefore, for example, as described in the outline of the embodiment, the volume of the dummy electrode 20 increases, and the gap between the dummy electrode 20 and the insulating layer 17 is reduced, thereby achieving various effects.

[0087] The thickness of the dummy electrode 20 may be greater than the thickness of the internal electrode 9 .

[0088] In this case, for example, the dummy electrode 20 shrinks relatively greatly due to firing, and the probability of gaps occurring is relatively high. The effect of the oxidized region 20x is useful because the gaps are reduced by forming the oxidized region 20x in the dummy electrode 20. While the shrinkage due to firing has been described, the same can be said for shrinkage due to temperature changes after fabrication and / or during use.

[0089] In a cross section parallel to the stacking direction (D3 direction), the ratio (first ratio) of the total area of ​​the oxidized regions 20x in the dummy electrode 20 to the area of ​​the dummy electrode 20 may be greater than the ratio (second ratio, which may be 0) of the total area of ​​the oxidized regions 9x in the internal electrode 9 to the area of ​​the internal electrode 9.

[0090] Here, if the degree of oxidation of the internal electrode 9 increases, for example, the electrical resistivity increases, degrading the electrical characteristics of the capacitor 1. On the other hand, since the dummy electrode 20 does not directly contribute to the electrical characteristics of the capacitor 1, it does not matter if the electrical resistivity increases due to oxidation. Therefore, by making the degree of oxidation of the dummy electrode 20 greater than the degree of oxidation of the internal electrode 9, it is easier to achieve the effect of reducing the gap associated with the dummy electrode 20 described above while maintaining the electrical characteristics of the capacitor 1.

[0091] In a cross section parallel to the stacking direction (D3 direction), the dummy electrode 20 may have an oxidized region 20x with a minimum diameter of 0.5 μm or more.

[0092] In this case, for example, the oxidized region 20x is relatively large, which improves the effect of reducing the gap. In particular, in a small capacitor 1, the thickness of the internal electrode 9 may be 1 μm or less, and the dummy electrode 20 may also be relatively thin. In such a configuration, the oxidized region 20x having a diameter of 0.5 μm or more functions effectively.

[0093] In a cross section parallel to the stacking direction (D3 direction), the dummy electrode 20 may have an oxidized region 20x that is large enough to cover the entire thickness of the dummy electrode 20.

[0094] In this case, the volume of the dummy electrode 20 increases to the maximum in the thickness direction in at least a part of the D1 direction (or the D2 direction) (excluding the effect of the oxygen concentration in the oxidized region 20x), thereby improving the effect of reducing the gap described above.

[0095] In a cross section parallel to the stacking direction (D3 direction) and a first direction (e.g., D1 direction) perpendicular to the D3 direction, the dummy electrode 20 may be located closer to the end than to the center in the D1 direction with respect to the cover 13 (the dummy electrode 20 shown in FIG. 4 is on the −D1 side). In the dummy electrode 20, the total area of ​​the oxidized region 20x in the half on the end side of the cover 13 may be larger than the total area of ​​the oxidized region 20x in the half on the center side of the cover 13.

[0096] In this case, for example, the gap is reduced closer to the end of the cover 13. As a result, for example, the unintended intrusion of gas and / or liquid into the gap is more likely to be prevented at the end of the cover 13. Therefore, the intrusion of gas and / or liquid into the depths of the dummy electrode 20 can be effectively reduced relative to the degree of oxidation of the entire dummy electrode 20. As a result, for example, the electrical characteristics of the capacitor 1 are more likely to be maintained.

[0097] The capacitor 1 may further have a base electrode 16 that overlaps the cover 13 from the side opposite to the effective portion 11. In a cross section parallel to the stacking direction (direction D3), the ratio of the total area of ​​the oxidized regions 20x in the dummy electrode 20 to the area of ​​the dummy electrode 20 may be larger than the ratio of the total area of ​​the oxidized regions (not shown) in the base electrode 16 to the area of ​​the base electrode 16.

[0098] Here, if the degree of oxidation of the base electrode 16 increases, for example, the adhesive strength of the external electrode 5 to the base electrode 16 decreases. On the other hand, although the dummy electrode 20 contributes to improving the adhesive strength of the external electrode 5, it has a smaller effect on peeling of the external electrode 5 than the base electrode 16. Therefore, by making the degree of oxidation of the dummy electrode 20 greater than the degree of oxidation of the base electrode 16, it is easier to achieve the effect of reducing the gap associated with the dummy electrode 20 described above while maintaining the peel strength of the external electrode 5.

[0099] The base electrode 16 does not necessarily have to have an oxidized region.

[0100] In this case, for example, the effect of reducing the gaps associated with the dummy electrodes 20 is improved while maintaining the peel strength of the external electrodes 5 described above.

[0101] As described above, in the embodiment in which the area ratio of the oxidized region 20 x in the dummy electrode 20 is larger than the area ratio of the oxidized region in the base electrode 16 , the dummy electrode 20 may be thinner than the base electrode 16 .

[0102] In this case, for example, by making the base electrode 16 that has a relatively strong adhesive force to the external electrode 5 relatively thick, the adhesive force of the external electrode 5 to the capacitor 1 can be efficiently improved.

[0103] The technology according to the present disclosure is not limited to the above-described embodiments and may be implemented in various forms.

[0104] For example, the multilayer electronic component is not limited to a capacitor. For example, in a multilayer electronic component, some of the multiple internal electrodes may form a capacitor, and the other multiple internal electrodes may form an inductor or resistor. The multilayer electronic component may also form an appropriate circuit (e.g., a resonant circuit) as a whole. Furthermore, the cover, base electrode, and external electrode may be provided on only one of the upper and lower surfaces of the active portion.

[0105] 1...capacitor, 5...external electrode, 7...dielectric layer, 9...internal electrode, 11...active portion, 13...cover, 17...insulating layer, 20...dummy electrode, 20x...oxidized region (of dummy electrode).

Claims

1. A multilayer electronic component comprising: an effective portion having dielectric layers and internal electrodes alternately stacked in a stacking direction; and a cover overlapping said effective portion in said stacking direction, said cover having a plurality of insulating layers stacked in said stacking direction; and a dummy electrode located between said plurality of insulating layers, said dummy electrode having at least one oxidized region.

2. The multilayer electronic component according to claim 1, wherein the thickness of the dummy electrodes is greater than the thickness of the internal electrodes.

3. The multilayer electronic component according to claim 1 or 2, wherein, in a cross section parallel to the lamination direction, the ratio of the total area of ​​the oxidized regions of the dummy electrodes to the area of ​​the dummy electrodes is greater than the ratio of the total area of ​​the oxidized regions of the internal electrodes to the area of ​​the internal electrodes.

4. The multilayer electronic component according to any one of claims 1 to 3, wherein the dummy electrode has an oxidized region with a minimum diameter of 0.5 μm or more in a cross section parallel to the lamination direction.

5. The multilayer electronic component according to any one of claims 1 to 4, wherein in a cross section parallel to the lamination direction, the dummy electrode has an oxidized region whose size extends across the entire thickness of the dummy electrode.

6. The multilayer electronic component according to any one of claims 1 to 5, wherein, in a cross section parallel to the stacking direction and a first direction perpendicular to the stacking direction, the dummy electrodes are located closer to the ends than to the center in the first direction with respect to the cover, and a total area of ​​the oxidized regions in a half of the dummy electrodes on the end side is larger than a total area of ​​the oxidized regions in a half of the dummy electrodes on the center side.

7. The multilayer electronic component according to any one of claims 1 to 6, further comprising a base electrode overlapping said cover from the opposite side to said effective portion, and in a cross section parallel to said lamination direction, a ratio of a total area of ​​oxidized regions of said dummy electrode to an area of ​​said dummy electrode is larger than a ratio of a total area of ​​oxidized regions of said base electrode to an area of ​​said base electrode.

8. The multilayer electronic component according to claim 7, wherein the base electrode does not have an oxidized region.

9. The multilayer electronic component according to claim 7 or 8, wherein the dummy electrodes are thinner than the base electrodes.

10. The multilayer electronic component according to any one of claims 1 to 9, wherein in a cross section parallel to the lamination direction, the ratio of the total area of ​​the oxidized regions in the dummy electrodes to the area of ​​the dummy electrodes is 5% or more.

11. The multilayer electronic component according to any one of claims 1 to 10, wherein in a cross section parallel to the lamination direction, a ratio of a total area of ​​an oxidized region in the dummy electrode to an area of ​​the dummy electrode is 20% or less.

Images