Multilayer Electronic Components

Abstract

The effective part of the multilayer electronic component has dielectric layers and internal electrodes that are alternately stacked. The cover overlaps the effective part in the stacking direction of the dielectric layers and the internal electrodes. The external electrode covers the side surfaces of the effective part and the cover along the stacking direction, and is connected to a partial edge portion that is a part of the outer edge of the internal electrode. In the external electrode, the first metal layer is made of a polycrystalline body and is in close contact with the side surfaces of the effective part and the cover, and the second metal layer is made of a polycrystalline body having a larger average grain size than the first metal layer and overlaps the side surfaces of the effective part and the cover from above the first metal layer. In the portion of the external electrode that extends in the stacking direction with the length of the partial edge portion as a width, the portion covering the side surfaces of the effective part is referred to as the first portion, and the portion covering the side surfaces of the cover is referred to as the second portion. In this case, the area ratio of the first metal layer in the first portion is smaller than the area ratio of the first metal layer in the second portion.

Description

[Technical field]

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

[0002] As an example of a multilayer electronic component, a multilayer ceramic capacitor is known (for example, Patent Document 1 below). A multilayer ceramic capacitor has, for example, a main body that directly functions as a capacitor, and external electrodes for mounting the capacitor on a circuit board or the like. The main body has alternately stacked dielectric layers and flat internal electrodes. The edges of the internal electrodes are exposed from the side surfaces (surfaces along the lamination direction) of the main body. The external electrodes are composed of, for example, metal layers that cover the side surfaces of the main body. Patent Document 1 proposes forming an oxide on the external electrodes in order to improve the adhesive strength of the external electrodes to the main body (ceramics). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-170875 A Summary of the Invention

[0004] A capacitor according to an embodiment of the present disclosure includes an effective portion, a cover, and an external electrode. The effective portion includes dielectric layers and internal electrodes that are alternately stacked. The cover overlaps the effective portion in the stacking direction of the dielectric layers and the internal electrodes. The external electrode covers the side surfaces of the effective portion and the cover along the stacking direction, and is connected to a partial edge portion that is a part of the outer edge of the internal electrode. The external electrode includes a first metal layer made of a polycrystalline body and in close contact with the side surfaces of the effective portion and the side surfaces of the cover, and a second metal layer made of a polycrystalline body having a larger average grain size than the first metal layer and overlapping the side surfaces of the effective portion and the side surfaces of the cover from above the first metal layer. In a portion of the external electrode that extends in the stacking direction with the length of the partial edge portion as a width, a portion that covers the side surfaces of the effective portion is referred to as a first portion, and a portion that covers the side surfaces of the cover is referred to as a second portion. In this case, the area ratio of the first metal layer in the first portion is smaller than the area ratio of the first metal layer in the second portion. [Brief description of the drawings]

[0005] [Figure 1] FIG. 1 is a perspective view showing a capacitor according to a first embodiment. [Diagram 2] FIG. 2 is a schematic exploded perspective view of the capacitor of FIG. 1. [Diagram 3] FIG. 2 is a cross-sectional view taken along line III-III in FIG. [Figure 4] An enlarged view of region R4 in FIG. [Diagram 5] A view of part of the capacitor shown in Figure 4 from the +D1 side. [Figure 6] FIG. 5 is an enlarged view of region R6 in FIG. [Figure 7] FIG. 7 is an enlarged view of region R7 in FIG. [Figure 8] FIG. 11 is a cross-sectional view showing another example of an external electrode. [Figure 9] FIG. 13 is a diagram showing yet another example of an external electrode. [Figure 10] FIG. 11 is a perspective view showing a capacitor according to a second embodiment. [Figure 11]1 is a table showing characteristics of capacitors according to examples and comparative examples. [Figure 12] FIG. 11 is a cross-sectional view showing another example of the dummy layer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] Hereinafter, an embodiment according to 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 match the actual ones. In addition, 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 the shapes and / or dimensions may be extracted from the drawings.

[0007] Regarding the aspect described relatively later, basically, only the difference from the aspect described relatively earlier will be described. Matters not specifically mentioned may be the same as the aspect described earlier or may be inferred from the aspect described earlier. For the sake of convenience, the same reference numerals may be used for components corresponding to each other in different aspects, 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 above-mentioned concept of shape is valid. For example, a corner formed by two sides may be chamfered to a length of 1 / 5, 1 / 10, or 1 / 20 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 (error). The same applies to other polygons, etc.

[0009] (Overview of the embodiment) Fig. 1 is a perspective view showing a capacitor 1 (an example of a multilayer electronic component) according to a first embodiment. For convenience, a Cartesian coordinate system D1D2D3 is attached to Fig. 1 and other figures described later. The capacitor 1 may be used with either side being the upper or lower. However, in the description of the embodiment, for convenience, the +D3 side may be regarded as the upper side, and terms such as the upper surface and the 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 D3 direction). 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. The main body 3 has, for example, an effective portion 13 and two covers 15 respectively overlapping the upper and lower surfaces of the effective portion 13. The effective portion 13 has a plurality of dielectric layers 7 and a plurality of internal electrodes 9 which are alternately overlapped. That is, the effective portion 13 directly functions as a capacitor. The covers 15 contribute, for example, to improving the strength of the main body 3.

[0012] Of the outer surfaces of the main body 3, the surfaces along the lamination direction (D3 direction) of the multiple dielectric layers 7 and multiple internal electrodes 9 are referred to as side surfaces. The multiple internal electrodes 9 have a portion of their edges (sometimes referred to as partial edge portions 9c) exposed from the side surfaces of the main body 3. The external electrodes 5 cover the side surfaces of the main body 3 and are fixed to the partial edge portions 9c. This electrically connects the internal electrodes 9 and the external electrodes 5. The internal electrodes 9 facing each other via the dielectric layers 7 are connected to different external electrodes 5.

[0013] Of the portions of the external electrode 5 covering the side surfaces of the main body 3, the portion covering the side surfaces of the effective portion 13 is referred to as the first portion 5a, and the portion covering the side surfaces of the cover 15 is referred to as the second portion 5b. In this case, the volume ratio of the oxide phase in the first portion 5a is smaller than the volume ratio of the oxide phase in the second portion 5b. This can improve, for example, the electrical characteristics.

[0014] More specifically, for example, an oxide phase generally has a higher electrical resistivity than a non-oxidized phase. Therefore, by reducing the volume ratio of the oxide phase in the first portion 5a, the resistance value between the outside of the capacitor 1 and the internal electrode 9 can be reduced. As a result, for example, a reduction in equivalent series resistance (ESR), an improvement in the Q value, a reduction in the amount of heat generated, and an improvement in high frequency performance can be expected.

[0015] 4 to 6, the reduction in the oxide phase in the first portion 5a does not necessarily result in a reduction in ESR, due to the method of reducing the volume fraction of the oxide phase in the first portion 5a, as described in detail later. However, the above method improves the fixing strength of the external electrode 5 to the main body 3. As a result, it is easier to achieve both an improvement in fixing strength and suppression of an increase in ESR, compared to an embodiment in which the fixing strength is improved by increasing the volume fraction of the oxide phase in the first portion 5a.

[0016] Furthermore, for example, when the main component of the external electrode 5 is copper, the oxide phase exhibits a rectifying effect, which may in turn destabilize the characteristics of the capacitor 1. However, by reducing the volume fraction of the oxide phase in the first portion 5a, the likelihood of such a problem occurring can be reduced.

[0017] The comparison of the volume ratios may be performed within the length range of the partial edge portion 9c of the internal electrode 9 in the direction along the outer periphery of the main body portion 3 (the direction along the outer edge of the dielectric layer 7). Specifically, the comparison is as follows.

[0018] 1 illustrates one partial edge 9c that is joined to the external electrode 5 on the -D1 side and the -D2 side on the side surface of the main body 3. In the illustrated example, the length (D1 direction) of the partial edge 9c and the length of the external electrode 5 in the direction along the partial edge 9c (D1 direction) are approximately equal. However, the external electrode 5 can be extended further toward the +D1 side than the length of the partial edge 9c, as shown by the two-dot chain line. In such a case, it is not necessarily reasonable in light of the above-mentioned effects to compare the portion covering the side surface of the effective portion 13 and the portion covering the side surface of the cover 15 over the entire length of the external electrode 5 in the D1 direction.

[0019] Therefore, the volume fractions of the oxide phase may be compared for a portion of the external electrode 5 that extends in the D3 direction (stacking direction of the dielectric layers 7) with the length of the partial edge portion 9c as its width (hereinafter, this portion may be referred to as the "target portion 5c"). That is, the above-mentioned first portion 5a may be the portion of the target portion 5c that covers the side surface of the effective portion 13. The second portion 5b may be the portion of the target portion 5c that covers the side surface of the cover 15. Usually, the lengths of the partial edge portions 9c in the multiple internal electrodes 9 are the same, but when they are different from each other, the length of the smallest range that includes all the partial edge portions 9c may be used as the length of the partial edge portion 9c (the width of the target portion 5c).

[0020] The above is an overview of the embodiment. As can be understood from the above, the capacitor (1) may have various configurations as long as it has an effective portion 13, a cover 15, and an external electrode 5 covering the side surfaces of these. In other words, the overall configuration of the capacitor 1 (first embodiment) shown in FIG. 1 is merely one example. However, for convenience, the overall configuration of the capacitor 1 will be described below, and then the oxide phase of the external electrode 5 and the like will be described based on the configuration of the capacitor 1. After that, the overall configurations of other capacitors (second embodiment, etc.) will also be described.

[0021] Specifically, the embodiment will be described in the following order. 1. Configuration of the capacitor according to the first embodiment (FIGS. 1 to 3) 1.1. Overall structure 1.2. Effective part 1.3.Cover 1.3.1. Covers in general Insulating Layer 1.3.3.Dummy electrodes 1.4.Outline of external electrode configuration 2. Specific configuration of external electrodes (Figs. 4 to 9) 2.1.Oxide phase 2.2. First Metal Layer Pattern 2.3. Materials and dimensions of the first and second metal layers 2.4. Other Examples of Specific Electrode Configurations 2.4.1. Other examples of partial edges of internal electrodes (Fig. 8) 2.4.2. Other examples of laminated structures of external electrodes (Fig. 8) 2.4.3. Other examples of first metal layer patterns (Figure 9) 3. Capacitor manufacturing method 3.1.Complete manufacturing procedure of the capacitor 3.2. Method of forming the pattern of the first metal layer 3.3. Method for forming specific shapes of internal electrodes 3.4. Method for reducing the volume fraction of oxide phase 4. Configuration of a capacitor according to another embodiment (FIG. 10) 5. Example (Figure 11) 6. Summary of the embodiment

[0022] (1. Configuration of the Capacitor According to the First Embodiment) (1.1. Overall structure) The capacitor 1 according to the first embodiment shown in Fig. 1 is configured as, for example, a surface-mounted chip-type component. Specifically, for example, the capacitor 1 is arranged with its -D3 side or +D3 side surface facing a circuit board (not shown). Then, the four pads of the circuit board and the four external electrodes 5 are respectively joined with a conductive joining material (for example, solder) (not shown) to mount the capacitor on the circuit board.

[0023] The configuration (internal structure and external shape) of the capacitor 1 is, for example, approximately plane-symmetric with respect to a symmetry plane (not shown) that is parallel to the D1D2 plane and passes through the center of the capacitor 1 in the thickness direction. Also, 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.

[0024] The shape of the main body 3 is, for example, generally a thin rectangular parallelepiped. This rectangular parallelepiped may be a square (as shown in the example) or a rectangle (excluding a square; the same applies below) in plan view. For convenience, in the description of the embodiments, a square shape may be used unless otherwise specified.

[0025] The specific dimensions of the main body 3 (or the capacitor 1) are arbitrary. As an example of dimensions when the capacitor 1 is relatively small, the lengths of the main body 3 (or the capacitor 1) in the D1 and D2 directions are each 300 μm or more and 1000 μm or less, and the thickness in the D3 direction is 30 μm or more and 100 μm or less.

[0026] In addition, multiple components of the same type (e.g., 5, 7, 9, 15, 17, 19, or 21, etc.) may be provided with the same (or corresponding) shape, size, material, and position, etc., unless otherwise specified or unless a contradiction occurs. For example, multiple dielectric layers 7 may be configured with the same shape, size, and material, and may overlap each other without excess or deficiency in a planar perspective. Therefore, unless otherwise specified or unless a contradiction occurs, a description of one component may be considered to be common to multiple components of the same type. Also, individual mention of multiple components of the same type being able to overlap each other without excess or deficiency in a planar perspective may be omitted.

[0027] A layered (membrane-like) component (e.g., 5, 7, 9, 17, or 21) may be entirely made of one material, but may also be made of layers of different materials stacked on top of each other.

[0028] (1.2. Effective part) The shape of the effective portion 13 shown in Fig. 3 is, for example, generally a thin rectangular parallelepiped. Its planar shape is the same as that of the main body portion 3. The specific thickness of the effective portion 13 is arbitrary. For example, the thickness of the effective portion 13 may be 0.2 to 0.9 times the thickness of the main body portion 3 (both thicknesses are based on the surface of the insulating portion).

[0029] The dielectric layer 7 is basically a layer having a constant thickness (at least between the internal electrodes 9). The thickness of the dielectric layer 7 may be set appropriately depending on the characteristics required of the capacitor 1. An example of a relatively thin thickness is a thickness between the internal electrodes 9 of 3 μm or less, or 1 μm or less. The shape and dimensions of the dielectric layer 7 in a planar view are the same as the shape and dimensions of the effective portion 13 in a planar view. The material of the dielectric layer is, for example, ceramics, and the specific type is also arbitrary. The number of laminated dielectric layers 7 (internal electrodes 9) is arbitrary. One example is 10 layers or more and 30 layers or less.

[0030] The internal electrodes 9 are in the form of layers having a certain thickness. The thickness of the internal electrodes 9 is arbitrary, and may be thinner, approximately the same as, or thicker than the thickness of the region between the internal electrodes 9 of the dielectric layer 7. The material of the internal electrodes 9 is, for example, a metal. The specific type of metal is arbitrary, and may be, for example, a base metal (e.g., Ni and Cu).

[0031] Fig. 2 is an exploded perspective view of the capacitor 1. Fig. 2 is a schematic view 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.

[0032] 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 extraction 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 13. The pair of extraction 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.

[0033] In the two internal electrodes 9 that face each other with the dielectric layer 7 in between (that is, are adjacent to each other with the dielectric layer 7 in between), a pair of lead electrodes 9b of one internal electrode 9 and a pair of lead electrodes 9b of the other internal electrode 9 are located on different diagonal lines in a planar perspective view. Both are connected to a pair of external electrodes 5 that are different from each other.

[0034] The electrode body 9a and the extraction electrode 9b may have any dimensions. For example, the length of the extraction electrode 9b on one side of the dielectric layer 7 (i.e., the length of the partial edge portion 9c) is approximately the same as the length of the external electrode 5 along the above-mentioned one side.

[0035] (1.3. Cover) (1.3.1. Covers in general) The cover 15 shown in FIG. 3 is provided, for example, on both the upper and lower surfaces of the effective portion 13. Unlike the illustrated example, the cover 15 may be provided on only one of the upper and lower surfaces of the effective portion 13. The cover 15 is, for example, layered with a shape and dimensions that overlap the effective portion 13 exactly in plan view. The thickness of the cover 15 is roughly constant. The proportion of the thickness of the cover 15 to the thickness of the main body portion 3 is the reverse of the proportion of the thickness of the effective portion 13 to the thickness of the main body portion 3 (as described above), and therefore a specific example of that proportion will be omitted.

[0036] Each cover 15 has, for example, at least one (plurality in the illustrated example) insulating layer 17 and at least one (plurality in the illustrated example) dummy layer 21 overlapping the insulating layer 17. Each dummy layer 21 has, for example, four dummy electrodes 19 as shown in FIG. 2. The dummy electrodes 19 contribute, for example, to reinforcing the cover 15 and / or improving the connection strength between the main body portion 3 and the external electrodes 5. Unlike the illustrated example, the cover 15 may have only one or more insulating layers 17 (it may not have the dummy layer 21).

[0037] When the dummy layer 21 is provided, for example, a metal can be deposited on the surface of the dummy layer 21 by electroless plating or electrolytic plating to produce the external electrode 5. Moreover, regardless of the presence or absence of the dummy layer 21, the external electrode 5 can be formed by a dipping method or a printing method.

[0038] The insulating layers 17 and the dummy layers 21 are alternately stacked one by one. In other words, the dummy layers 21 are provided at the boundaries of all the insulating layers 17. Unlike the illustrated example, the dummy layers 21 may be provided only at some of the boundaries. For example, the dummy layers 21 may not be provided at one or more boundaries relatively close to the effective portion 13, and the dummy layers 21 may be provided only at one or more boundaries relatively far from the effective portion 13. However, in such a case, two or more insulating layers 17 that are in close contact with each other without the dummy layers 21 interposed therebetween may be regarded as one insulating layer 17.

[0039] There may be only one dummy layer 21. FIG. 12 shows an example different from the example of FIG. 3. In this example, one dummy layer 21 is provided on each of the upper and lower surfaces of the main body 3. More specifically, this dummy layer 21 is exposed from the upper or lower surface of the main body 3, and is insulated from the internal electrode 9 by one insulating layer 17 or one dielectric layer 7. In the example of FIG. 12, the dummy layer 21 is thicker than that in the example of FIG. 3, and has a thickness of, for example, 1 / 2 or more or 2 / 3 or more of the thickness of the cover 15 (of course, it is not necessary to have such a thickness). For convenience, the embodiment may be described on the premise of the aspect of FIG. 12 without any particular notice.

[0040] (1.3.2. Insulating Layer) The insulating layer 17 is a layer having a generally constant thickness, except for variations in thickness resulting from the presence or absence of overlap with the conductor layers (9 and 19). The planar shape of the insulating layer 17 is, for example, 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 the material of the dielectric layer 7, or may be different. Furthermore, the material of the insulating layer 17 may be, for example, ceramics, or a material other than ceramics.

[0041] The thickness of the insulating layer 17 is arbitrary. For example, the thickness of the insulating layer 17 may be thicker (as in the illustrated example) than the thickness of the dielectric layer 7 (either the thickness between the conductor layers or the thickness of the region not overlapping the conductor layers; the same applies below in this paragraph), may be equal to the thickness, or may be thinner. For example, the thickness of the insulating layer 17 may be two or more times, five or more times, or ten or more times the thickness of the dielectric layer 7, and may be 5 μm or more and 20 μm or less.

[0042] 3, the top layer of the effective portion 13 is a conductor layer including an internal electrode 9. The top internal electrode 9 is covered with a bottom insulating layer 17 of the upper cover 15. However, as long as the top internal electrode 9 and the dummy electrode 19 of the upper cover 15 are insulated from each other, the configuration at the boundary may be different from that shown in the illustrated example.

[0043] For example, the uppermost layer of the effective portion 13 may be the dielectric layer 7. The uppermost dielectric layer 7 may overlap the lowermost insulating layer 17 of the upper cover 15, or the uppermost dielectric layer 7 may overlap the lowermost dummy electrode 19. All of the dielectric layers 7 and all of the insulating layers 17 do not need to be distinguishable from each other in terms of their materials, thicknesses, etc. From another perspective, the boundary between the effective portion 13 and the cover 15 may be ambiguous.

[0044] However, in either embodiment, the material between the internal electrodes 9 functions as a dielectric for increasing the capacitance. Also, the material between the uppermost one of the multiple internal electrodes 9 and the lowermost one of the multiple dummy electrodes 19 of the upper cover 15 functions as an insulating layer for insulating them. From this point of view, the insulating layer between the uppermost one of the multiple internal electrodes 9 and the lowermost one of the multiple dummy electrodes 19 may be regarded as the insulating layer 17 of the cover 15, regardless of whether it has the same configuration as the dielectric layer 7 between the internal electrodes 9 or the insulating layer 17 between the dummy layers 21, or whether it is a combination of the previous two layers.

[0045] Although the upper cover 15 is taken as an example, the same applies to the lower cover 15. However, the words "top layer" and "bottom layer" are interchangeable.

[0046] (1.3.3. Dummy Electrode) The dummy electrode 19 (in other words, the dummy layer 21) is, for example, a layer having a certain thickness. The material of the dummy electrode 19 is, for example, a metal. The specific type of metal is arbitrary, and is, for example, a base metal (e.g., Ni and Cu). The material of the dummy electrode 19 may be the same as the material of the internal electrode 9, or may be different.

[0047] In a plan view, the position, shape and size of the dummy electrode 19 are arbitrary. In the example of FIG. 2, the dummy electrode 19 is located at the four corners of the dielectric layer 7 in a planar perspective view. From another perspective, the position of the dummy electrode 19 corresponds to the position of the external electrode 5. The planar shape of the dummy electrode 19 is rectangular (more specifically, square). The size of the dummy electrode 19 in a plan view is approximately the same as the size of the external electrode 5 in a plan view.

[0048] The dummy electrode 19 may overlap the electrode body 9a in plan view (overlapping a corner of the internal electrode 9 in the illustrated example), or may not overlap. In the latter case, the dummy electrode 19 may be formed, for example, in an L-shape along a corner (two intersecting sides) of the dielectric layer 7. When the dummy electrode 19 overlaps the internal electrode 9, for example, a wide area of ​​the dummy electrode 19 is ensured, and therefore the effect of improving the strength by the dummy electrode 19 is improved. When the dummy electrode 19 does not overlap the internal electrode 9, for example, the electrical influence of the dummy electrode 19 on the internal electrode 9 is reduced.

[0049] The dummy electrode 19 is exposed, for example, on a side surface of the main body 3. This exposed portion is fixed to the external electrode 5. This allows the dummy electrode 19 to contribute to improving the bonding strength between the main body 3 and the external electrode 5. Unlike the example shown in the figure, the dummy electrode 19 does not have to be connected to the external electrode 5. For example, the dummy electrode 19 may be provided so as not to be exposed from the side surface of the main body 3, and may contribute to improving the strength of the main body 3 without contributing to improving the connection strength with the external electrode 5.

[0050] The thickness of the dummy electrode 19 is arbitrary. For example, the thickness of the dummy electrode 19 may be thicker than the thickness of the internal electrode 9 (in the illustrated example), may be approximately the same as the thickness of the internal electrode 9, or may be thinner. For example, the thickness of the dummy electrode 19 may be two or more times, five or more times, or ten or more times the thickness of the internal electrode 9. Furthermore, the thickness of the dummy electrode 19 may be thinner than the thickness of the insulating layer 17 (in the illustrated example), may be the same as the thickness of the internal electrode 9, or may be thicker than the thickness of the insulating layer 17.

[0051] 3, a dummy layer 21 is provided on the top layer of the upper cover 15. The four dummy electrodes 19 are covered with the external electrodes 5. Unlike the illustrated example, the dummy layer 21 does not have to be provided on the top layer of the upper cover 15. As described above, the dummy layer 21 affects the method of forming the external electrodes 5, and therefore the presence or absence of the dummy layer 21 on the top layer may be determined taking this effect into consideration.

[0052] As described above, the layered (film-like) component may be composed of two or more layers. The external electrode 5 may also be composed of two or more layers. In this case, the lower layer of the external electrode 5 and the uppermost dummy electrode 19 may or may not be distinguishable from the viewpoint of thickness and / or material. Therefore, the presence or absence of the dummy electrode 19 may be recognized based on the presence or absence of the dummy electrode 19 covered by the insulating layer 17 from the side opposite to the effective portion 13 (dielectric layer 7).

[0053] In the illustrated example, the four dummy electrodes 19 overlap the internal electrodes 9 in a planar perspective view, and the four dummy electrodes 19 are connected to external electrodes 5 at different potentials. Therefore, the dummy layer 21 and the internal electrodes 9 need to be separated by the dielectric layer 7 and / or the insulating layer 17. However, this does not apply in cases where some or all of the four dummy electrodes 19 do not overlap the internal electrodes 9 in a planar perspective view, or where some or all of the four dummy electrodes 19 are not connected to the external electrodes 5.

[0054] (1.4. Schematic configuration of external electrodes) 1 is, for example, generally in the form of a layer covering four faces (upper face, lower face, and two side faces) of the main body 3 at the corners in a plan view of the main body 3. This allows one external electrode 5 to be connected to one extraction electrode 9b on two side faces of the main body 3, and also makes it possible to surface mount the capacitor 1 on either the upper or lower face. Note that, if a decrease in practicality is ignored, for example, the external electrode 5 may cover only two faces (a combination of the upper or lower face and one side face).

[0055] The shape, dimensions, and material of the portions on each surface of the external electrode 5 are arbitrary. The planar shape of the portion of the external electrode 5 located on the upper or lower surface of the main body 3 is, for example, rectangular (square in the illustrated example). 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 lateral length as the portion located on the upper or lower surface. The thickness of the external electrode 5 (film) may be, for example, thicker than the thicknesses of the internal electrodes 9 and dummy electrodes 19.

[0056] (2. Specific Configuration of External Electrodes) A specific configuration of the external electrode 5 with respect to the volume fraction of the oxide phase, etc. will be described. As described above, in the capacitor 1 according to the first embodiment, one external electrode 5 overlaps two side surfaces of the main body portion 3. However, in the following description, for convenience, attention is focused only on the portion of one external electrode 5 that overlaps one side surface. On that premise, the number of each portion, etc. may be mentioned. Furthermore, the requirements with respect to the volume fraction of the oxide phase, etc. for one external electrode 5 only need to be satisfied for one side surface. However, they may also be satisfied for both side surfaces as a whole.

[0057] As described with reference to FIG. 1 in the description of the outline of the embodiments, the requirements regarding the volume ratio of the oxide phase, etc., only need to be satisfied within the range of the length of the partial edge portion 9c (target portion 5c of the external electrode 5) in the direction along the outer periphery of the main body portion 3 (direction D1 or direction D2). However, in the first embodiment, the length of the external electrode 5 and the length of the partial edge portion 9c in the above direction are approximately equal. That is, the entire portion of the external electrode 5 located on one side surface may be regarded as the target portion 5c. Therefore, any reference to the target portion 5c may be omitted.

[0058] (2.1. Oxide Phase) Fig. 4 is an enlarged view of region R4 in Fig. 3. As shown in this figure, the external electrode 5 has a laminated structure made up of a first metal layer 23 and a second metal layer 25. The first metal layer 23 is in close contact with (or from another perspective, directly overlaps) the outer surface (e.g., side surface) of the main body portion 3. The second metal layer 25 overlaps the side surface of the main body portion 3 from above the first metal layer 23. From another perspective, the second metal layer 25 is in close contact with the outer surface of the first metal layer 23.

[0059] Fig. 5 is a view of a part of the portion shown in Fig. 4 as seen from the +D1 side. In other words, Fig. 5 is a view of the external electrode 5 located on the +D1 side and the +D2 side and its surroundings as seen in the direction indicated by the arrow a1 in Fig. 1. In Fig. 5, the second metal layer 25 is omitted. Also, the internal electrode 9 (more specifically, the partial edge portion 9c of the lead electrode 9b) and the dummy electrode 19, which are covered by the external electrode 5 and cannot be seen, are shown by dotted lines. Note that Fig. 4 is a cross-sectional view taken along the line IV-IV in Fig. 5.

[0060] 4 and 5, the first metal layer 23 does not extend continuously (in other words, without gaps) across the region where the external electrodes 5 are arranged, but extends discontinuously. In other words, a non-arrangement area A1 of the first metal layer 23 is formed on the side surface of the main body portion 3. The non-arrangement area A1 is mainly located on the side surface of the effective portion 13. In the non-arrangement area A1, the second metal layer 25 is in close contact with the side surface of the main body portion 3, not with the first metal layer 23.

[0061] Fig. 6 is an enlarged view of region R6 in Fig. 4. As shown in this figure, the outer surface of the first metal layer 23 (the surface opposite to the main body portion 3) is oxidized. From another perspective, the first metal layer 23 has a first material layer 23a and a first oxide layer 23b covering the first material layer 23a. The material of the first oxide layer 23b is an oxide of the material constituting the first material layer 23a.

[0062] Similar to the first metal layer 23, the outer surface of the second metal layer 25 is oxidized. From another perspective, the second metal layer 25 has a second material layer 25a and a second oxide layer 25b covering the second material layer 25a. The material of the second oxide layer 25b is an oxide of the material constituting the second material layer 25a.

[0063] As described above, the non-disposition area A1 of the first metal layer 23 is mainly located on the side surface of the effective portion 13 among the side surfaces of the main body portion 3. Therefore, the area ratio of the first oxide layer 23b on the side surface of the effective portion 13 is smaller than the area ratio of the first oxide layer 23b on the side surface of the cover 15. As a result, in the external electrode 5, the volume ratio of the oxide phase in the first portion 5a is smaller than the volume ratio of the oxide phase in the second portion 5b.

[0064] Here, the volume ratio of the oxide phase in the first portion 5a is the ratio of the volume of the oxide phase present in the first portion 5a to the volume of the external electrode 5 present in the first portion 5a, and the volume ratio of the oxide phase in the second portion 5b is the ratio of the volume of the oxide phase present in the second portion 5b to the volume of the external electrode 5 present in the second portion 5b. Moreover, the area ratio of the first oxide layer 23b on the side surface of the effective portion 13 is the ratio of the area of ​​the first oxide layer 23b present in the first portion 5a to the area of ​​the first portion 5a, and the area ratio of the first oxide layer 23b on the side surface of the cover 15 is the ratio of the area of ​​the first oxide layer 23b present in the second portion 5b to the area of ​​the second portion 5b.

[0065] For the sake of simplicity, the first material layer 23a and the first oxide layer 23b are clearly distinguished from each other, but the boundary between them does not have to be clear. From another perspective, the first material layer 23a may include an oxide phase, and conversely, the first oxide layer 23b may include a phase that is not an oxide phase. The same applies to the second material layer 25a and the second oxide layer 25b.

[0066] As described above, in the capacitor 1 according to the embodiment, the volume ratio of the oxide phase in the first portion 5a is reduced by making the first metal layer 23 discontinuous on the side surface of the effective portion 13. In this case, for example, the volume ratio of the oxide phase in the first portion 5a can be easily reduced while making the external electrode 5 a laminated structure. By making the external electrode 5 a laminated structure, for example, it is possible to deal with the difference between the inner surface side and the outer surface side regarding the function required of the external electrode 5. For example, the first metal layer 23 may have a high adhesion strength to the internal electrode 9 and / or the dielectric layer 7. The second metal layer 25 may be made to have a thickness that can be easily secured in terms of time and / or cost. Examples of the effects of reducing the volume ratio of the oxide phase in the first portion 5a have already been described.

[0067] By making the first metal layer 23 discontinuous in the effective portion 13 and / or the cover 15, effects from a different viewpoint than the above can be achieved. For example, when the first metal layer 23 is discontinuous, the surface area of ​​the first metal layer 23 becomes relatively large with respect to the volume of the first metal layer 23. Therefore, for example, the affinity between the first metal layer 23 and the second metal layer 25 can be improved while reducing the volume of the first metal layer 23. In addition, for example, the unevenness caused by the discontinuous first metal layer 23 has an anchor effect. For these reasons, for example, the thickness of the external electrode 5 can be secured by the relatively inexpensive second metal layer 25, while the fixing strength of the external electrode 5 to the main body portion 3 can be improved.

[0068] Whether or not the requirement that the volume fraction of the oxide phase in the first portion 5a is smaller than the volume fraction of the oxide phase in the second portion 5b is satisfied may be determined by an appropriate method. For example, in a mode in which the thicknesses of the first oxide layer 23b and the second oxide layer 25b can be substantially regarded as being approximately constant, the volume fraction is determined by the area of ​​the first oxide layer 23b (i.e., the surface area of ​​the first metal layer 23). Therefore, by comparing the area fraction of the first metal layer 23 between the first portion 5a and the second portion 5b, it may be determined whether or not the above requirement is satisfied.

[0069] Here, the area ratio of the first metal layer 23 in the first portion 5a is the ratio of the area of ​​the first metal layer 23 present in the first portion 5a to the area of ​​the first portion 5a, and the area ratio of the first metal layer 23b in the second portion 5b is the ratio of the area of ​​the first metal layer 23 present in the second portion 5b to the area of ​​the second portion 5b.

[0070] In the above case, if the area ratio of the first metal layer 23 in the first portion 5a is smaller than the area ratio of the first metal layer 23 in the second portion 5b by any amount, it may be determined that the above requirement is satisfied. However, taking into consideration measurement errors and the like, it may also be determined that the above requirement is satisfied when the area ratio of the former is 0.95 or less, 0.90 or less, or 0.80 or less relative to the area ratio of the latter. The area ratio may be determined based on the manufacturing process, or by analyzing the external electrode 5 after manufacturing. In the latter case, the area ratio may be determined, for example, by imaging and analyzing a mirror surface obtained by polishing the surface or cross section of the external electrode 5.

[0071] Even when the magnitude relationship of the volume ratio of the oxide phase is not specified by the area ratio of the first oxide layer 23b, the magnitude relationship may be determined based on the manufacturing process, or by analyzing the external electrode 5 after manufacturing. In the latter case, for example, an appropriate analysis device that performs qualitative and quantitative analysis of materials may be used. The measurement by the analysis device may be either a physical method or a chemical method, and may be either destructive or non-destructive. In addition, the measurement may be performed on the entire amount of each part (5a and 5b), or on multiple extracted parts of each part.

[0072] In addition, when the boundary between the first portion 5a and the second portion 5b is unclear, the volume ratios of the oxide phases of both portions may be compared by excluding the unclear portion to the minimum necessary size.

[0073] (2.2. First Metal Layer Pattern) The specific pattern for making the first metal layer 23 discontinuous is arbitrary. In the example shown in Fig. 5, the first metal layer 23 has a plurality of extending portions 23e in the effective portion 13, which extend along the D2 direction (a direction intersecting the stacking direction of the dielectric layers 7 and the internal electrodes 9). The positions of the plurality of extending portions 23e in the D3 direction (the stacking direction of the dielectric layers 7 and the internal electrodes 9) are different from one another. In other words, the plurality of extending portions 23e are spaced apart from one another in the D3 direction. This makes the first metal layer 23 discontinuous in the D3 direction.

[0074] At least one of the multiple extension portions 23e (all of them in the example of FIG. 5) has a discontinuity A3 midway in the D2 direction. From another perspective, the extension portion 23e has multiple separation portions 23f that are spaced apart from each other in the D2 direction. In other words, the first metal layer 23 has multiple separation portions 23f that are distributed apart from each other in the D2 and D3 directions. As a result, the first metal layer 23 is discontinuous not only in the D3 direction, but also in the D2 direction.

[0075] The portion of the first metal layer 23 that is a single unit (separation portion 23f in the illustrated example) may be single crystal or polycrystalline. In other words, in the former case, separation portion 23f may be a crystal that has grown in an island shape. Although not particularly illustrated, the island-shaped crystal may be even smaller than separation portion 23f in the illustrated example, and may not fit the concept of a portion obtained by dividing extension portion 23e in the length direction. For example, the grain size of the island-shaped crystal (in other words, crystal grain) may be smaller than the thickness of internal electrode 9. In the description of the embodiment, for convenience, it may be assumed that separation portion 23f is polycrystalline without any particular mention.

[0076] The specific positions, shapes, and dimensions of the multiple extensions 23e and multiple separations 23f are arbitrary. In the example of Fig. 5, the extensions 23e extend along a partial edge 9c (an edge exposed from the effective portion 13) of the internal electrode 9 while covering the partial edge 9c. Also, as shown in Figs. 4 and 5, the partial edge 9c has a non-exposed portion 9d (reference numeral in Fig. 4) that is not exposed from the side surface of the effective portion 13. The discontinuity A3 of the extensions 23e overlaps with the non-exposed portion 9d when seen through in the D1 direction (the normal direction of the first portion 5a).

[0077] 5, the shape of the extension portion 23e and the shape of the separation portion 23f are formed in an elongated shape extending with a generally constant width (length in the D3 direction). Unlike the illustrated example, the shape of the separation portion 23f (or the extension portion 23e) may be an ellipse with the D2 direction as the longitudinal direction. Furthermore, the shape of the separation portion 23f may be a shape that does not have a longitudinal direction (for example, a circular shape) or a shape with the D3 direction as the longitudinal direction.

[0078] When the extending portion 23e (or the separating portion 23f) extends in the D2 direction, it is sufficient that the maximum length in the D2 direction is longer than the maximum length in the D3 direction, for example. However, the former may be two or more times or five or more times the latter.

[0079] Furthermore, when the first metal layer 23 has a plurality of extending portions 23e at different positions in the D3 direction (or when the plurality of extending portions 23e are separated from one another in the D3 direction), the plurality of extending portions 23e do not have to be completely separated from one another. For example, when the extending portion 23e (or the separating portion 23f) is elliptical as described above, the wide portions of the adjacent extending portions 23e (separating portions 23f) may be connected to each other.

[0080] The number of interruptions A3 in one extending portion 23e is arbitrary, and may be one (as in the illustrated example) or may be two or more. The length of the interruptions A3 in the D2 direction is also arbitrary. For example, in one extending portion 23e, the total length of one or more interruptions A3 may be shorter than the total length of the uninterrupted portions of the extending portion 23e.

[0081] As described above, in the first embodiment, one external electrode 5 overlaps two side surfaces of the effective portion 13, and is fixed at the two side surfaces to partial edge portions 9c of the internal electrode 9. Two extension portions 23e connected to the same internal electrode 9 and located on two side surfaces may be connected to each other (see the first, third, and fifth extension portions 23e from the top in FIG. 5), or may not be connected to each other (see the other extension portions 23e in FIG. 5).

[0082] More specifically, the number and width of the extensions 23e and the number and length of the interruptions A3 may be set so as to realize, for example, an example of the coverage value of the first metal layer 23 described in the embodiment described later. Specifically, the ratio of the area of ​​the side surface of the effective portion 13 covered by the first portion 5a (first region) to the area of ​​the first region may be set to, for example, 50% or more and 95% or less. Then, the number and width of the extensions 23e and the number and length of the interruptions A3 may be set so as to realize this area ratio.

[0083] (2.3. Materials and dimensions of the first and second metal layers) The thickness of the first metal layer 23 and the second metal layer 25 is arbitrary. For example, the thickness of the first metal layer 23 (e.g., the maximum thickness; the same applies below in this paragraph) may be 0.2 μm or more and 3 μm or less. The thickness of the second metal layer 25 (e.g., the minimum thickness on the first metal layer 23; the same applies below in this paragraph) may be 2 μm or more and 10 μm or less. The second metal layer 25 may be thicker than the first metal layer 23. For example, the thickness of the second metal layer 25 may be 1.5 times or more or 10 times or more the thickness of the first metal layer 23.

[0084] The material of the first metal layer 23 and the second metal layer 25 is arbitrary. For example, the material of the first material layer 23a and the second material layer 25a or its main component may be a base metal. The base metal may be, for example, Cu, Ni, or an alloy containing at least one of Cu and Ni (e.g., a Cu-Ni alloy). The main component may be, for example, a component that occupies 60 mass % or more or 80 mass % or more of the material (the same applies to layers other than the first metal layer 23 and the second metal layer 25). When the material is Cu, Ni, or a Cu-Ni alloy, unintended impurities may be present. The impurities may be, for example, less than 1 mass % of the material. The material of the first oxide layer 23b and the second oxide layer 25b or its main component may be an oxide of the material exemplified above. For example, the oxide may be Cu, 2 O, CuO, NiO or Ni 2 O 3 It may be.

[0085] The materials or main components of the first metal layer 23 and the second metal layer 25 may be the same or different from each other. The difference between the materials may be, for example, based only on the component ratio of the elements, or based on the grain size of the crystal grains in addition to the component ratio of the elements (similar to the first metal layer 23 and the second metal layer 25). Even if the elements and grain size of the first metal layer 23 and the second metal layer 25 are the same, the first oxide layer 23b can confirm the existence of the first metal layer 23 and the second metal layer 25 in the configuration illustrated in FIG. 6. The material or main component of at least one of the first metal layer 23 and the second metal layer 25 may be the same as the material or main component of the internal electrode 9, or may be different.

[0086] Fig. 7 is an enlarged view of region R7 in Fig. 6. In this figure, crystal grains are depicted for the first metal layer 23 and the second metal layer 25. However, whether or not they are oxide phases is omitted. Moreover, crystal grains are omitted for portions other than the first metal layer 23 and the second metal layer 25.

[0087] As shown in this figure, the first metal layer 23 and the second metal layer 25 are, for example, made of polycrystals. That is, the first metal layer 23 has a plurality of first crystal grains 23p, and the second metal layer 25 has a plurality of second crystal grains 25p. The grain sizes of the two may be larger than one another (as shown in the example) or may be the same. In the example shown in the figure, the grain size of the first crystal grains 23p is smaller than the grain size of the second crystal grains 25p.

[0088] The particle size referred to here may be, for example, the circle equivalent diameter in the cross section (two-dimensional image from another point of view) of the metal layers (23 and 25). Furthermore, the particle sizes compared in the first metal layer 23 and the second metal layer 25 may be average particle sizes unless otherwise specified. The average particle size may be, for example, the particle size at which the area ratio becomes 50% when the areas of the smallest particle sizes are integrated in the above two-dimensional image. In other words, the average particle size may be the average value based on the area. The particle sizes of the first metal layer 23 and the second metal layer 25 may not distinguish whether they are oxide phases or not.

[0089] The specific values ​​of the grain size of the first crystal grains 23p and the grain size of the second crystal grains 25p and the difference between them are arbitrary. For example, the average grain size of the first crystal grains 23p may be less than 1 μm, more specifically, 0.1 μm or more and less than 1 μm. The average grain size of the second crystal grains 25p may be 1 μm or more, more specifically, 1 μm or more and less than 10 μm. The average grain size of the second crystal grains 25p may be two or more times or five or more times the average grain size of the first crystal grains 23p.

[0090] The grain size may be measured, for example, by mirror-finishing the surface or cross section of the metal layers (23 and 25), appropriately chemically etching the surface to clarify the grain boundaries, and imaging the mirror surface with an electron microscope. More specifically, for example, the first metal layer 23 is imaged at a scale including 30 to 50 first crystal grains 23p. The second metal layer 25 is imaged at a scale including 30 to 50 second crystal grains 25p. The scales may be different from each other. Then, known image processing is performed on the image of each metal layer to calculate the circle equivalent diameter. Multiple images may be imaged until the variation due to the imaging position converges, and the average value of the average grain size may be calculated.

[0091] Unlike the above, there are cases where it is desired to confirm the presence of the first metal layer 23 and the second metal layer 25 by identifying the presence of regions with different crystal grain sizes. In such a case, for example, in an embodiment in which the difference in grain size between the first crystal grains 23p and the second crystal grains 25p is large as shown in FIG. 7, the presence of the difference in grain size can be identified by visual inspection of the image, and the presence of the first metal layer 23 and the second metal layer 25 can be confirmed. In other embodiments, for example, images of a plurality of continuous regions are taken while appropriately changing the scale so that 30 to 50 crystal grains are included, and the grain size (circle equivalent diameter) of each crystal grain is measured. Then, the change in grain size of crystal grains located on a predetermined straight line spanning the plurality of regions may be analyzed to confirm the presence of the first metal layer 23 and the second metal layer 25. For example, when a moving average of the grain sizes of five or ten consecutive crystal grains along a straight line is calculated, the presence of the first metal layer 23 and the second metal layer 25 can be confirmed when the grain size at the peak (second metal layer 25) is more than two or five times the grain size at the valley (first metal layer 23).

[0092] (2.4. Other Examples of Specific Electrode Configurations) The following describes other examples of specific configurations of the internal electrode 9 and the external electrode 5. The examples already described and the other examples to be described below may be combined as appropriate.

[0093] (2.4.1. Other Examples of Partial Edges of Internal Electrodes) FIG. 8 is a diagram showing another example of the internal electrode 9 and the external electrode 5, and corresponds to FIG.

[0094] In the internal electrode 9, the thickness of the partial edge portion 9c (the portion exposed from the side surface of the effective portion 13) may be thicker than the portion inside the partial edge portion 9c. From another perspective, the exposed area of ​​the partial edge portion 9c to the outside may be made larger. The first metal layer 23 may cover the entire thickness of the partial edge portion 9c. In other words, the bonding area between the partial edge portion 9c and the first metal layer 23 may be expanded in the thickness direction (direction D3) of the internal electrode 9 compared to the embodiment of FIG. 4. In the following, the partial edge portion 9c that is thickened as described above may be referred to as the expanded edge portion 9e.

[0095] In the illustrated example, only two types of edges, the extended edge 9e and the non-exposed portion 9d, are shown as edges constituting the partial edge 9c. However, these edges and an edge having the same thickness as the thickness of the inner part of the internal electrode 9 (see FIG. 4; hereinafter, referred to as the "normal edge 9f") may be provided as appropriate. For example, other than the embodiments shown in FIG. 4 and FIG. 9, there are an embodiment in which the above three types of edges are provided, an embodiment in which the normal edge 9f and the extended edge 9e are provided, an embodiment in which only the normal edge 9f is provided, and an embodiment in which only the extended edge 9e is provided. In an embodiment in which both the normal edge 9f and the extended edge 9e are provided, the two may be provided on different partial edges 9c, or may be provided on the same partial edge 9c.

[0096] The specific shape and dimensions of the extended edge portion 9e are arbitrary. In the illustrated example, the extended edge portion 9e is shaped to gradually become thicker by equal amounts on both the top and bottom sides as it moves toward the outside (the external electrode 5 side). Examples of other shapes include a shape that is thicker only upward or downward, a shape that is thicker on both the top and bottom sides but the amount of thickening on one side is greater than the amount of thickening on the other side, and a shape that is thicker not gradually but has a step and / or is bent at the edge of the internal electrode 9. The thickness (e.g., maximum thickness) of the extended edge portion 9e may be, for example, 1.2 times or more, 1.5 times or more, or 2 times or more the thickness of the inner part of the internal electrode 9.

[0097] (2.4.2. Other Examples of Layered Structure of External Electrodes) The external electrode 5A shown in FIG. 8 is obtained by adding a third metal layer 27 and a fourth metal layer 29 to the external electrode 5 shown in FIG. 4. The third metal layer 27 and the fourth metal layer 29 contribute to, for example, reducing solder erosion of the second metal layer 25, reducing oxidation of the second metal layer 25, and / or improving the bonding strength to a bonding material (for example, solder). Only one of the third metal layer 27 and the fourth metal layer 29 may be provided, or another metal layer may be provided. The material and thickness of the third metal layer 27 and the fourth metal layer 29 may be appropriately set according to the purpose of these layers. For example, in the embodiment in which the first metal layer 23 and the second metal layer 25 are Cu as described above, the third metal layer 27 may be Ni, and the fourth metal layer 29 may be Sn.

[0098] 8, the outer electrode 5A is combined with an inner electrode 9 having an extended edge 9e and an unexposed portion 9d, although it is clear that the outer electrode 5A may be combined with an inner electrode 9 that does not have the extended edge 9e and / or the unexposed portion 9d.

[0099] (2.4.3. Other Examples of First Metal Layer Patterns) FIG. 9 is a diagram showing another example of the pattern of the first metal layer 23, and corresponds to FIG.

[0100] 9, the extension 23e does not have a discontinuity A3. In other words, the first metal layer 23 is discontinuous in the D3 direction (stacking direction) but is continuous in the D2 direction (direction intersecting the stacking direction). In addition, the partial edge 9c of the internal electrode 9 does not have a non-exposed portion 9d.

[0101] It is apparent that the partial edge 9c shown in Fig. 9 may be a normal edge 9f (Fig. 4) or an extended edge 9e (Fig. 8), or a combination of these. Depending on the method of forming the pattern of the first metal layer 23 (described later), the first metal layer 23 in the pattern shown in Fig. 9 may be combined with a non-exposed portion 9d.

[0102] (3. Capacitor manufacturing method (3.1. Overall Capacitor Manufacturing Procedure) The capacitor 1 may be manufactured by various methods. For example, the outline of the manufacturing process may be the same as a known process. An example is shown below.

[0103] First, ceramic green sheets that will become the dielectric layer 7 and the insulating layer 17 are prepared. Next, a conductive paste that will become the internal electrodes 9 or dummy electrodes 19 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 effective portion 13 and the stacking of the portion that will become the cover 15 on the laminate may be performed together or separately.

[0104] The above-mentioned steps up to the production of the laminate are carried out, for example, on a mother board of a size from which a large number of main body parts 3 are obtained. After the production of the laminate, the mother board including the laminate is diced (e.g., cut) into pieces of a size roughly corresponding to the size of the main body parts 3. Next, the laminate having the size of the main body parts 3 is fired. After that, a metal film is formed on the main body parts 3, and the external electrodes 5 are formed.

[0105] Degreasing may be performed before firing. Firing may be performed, for example, in a reducing atmosphere. Reoxidation 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. By polishing, partial edge portions 9c of the internal electrodes 9 and edges of the dummy electrodes 19 may be exposed from the side surfaces of the main body portion 3.

[0106] (3.2. Method of forming a pattern of the first metal layer) There is no particular limitation on the method for making the first metal layer 23 discontinuous. The following is an example.

[0107] Metal may be deposited by electroless plating or electrolytic plating on the surfaces of the internal electrodes 9 and dummy electrodes 19 that are exposed to the outside of the main body 3 (hereinafter, sometimes referred to as "exposed surfaces"), thereby forming the first metal layer 23. In this case, the pattern of the first metal layer 23 is based on the patterns of the exposed surfaces of the internal electrodes 9 and dummy electrodes 19. Therefore, by forming the patterns of the exposed surfaces of the internal electrodes 9 and dummy electrodes 19 into an appropriate shape and by preventing the metal deposited on the exposed surfaces from being connected via the non-placement areas of the exposed surfaces, the first metal layer 23 can be formed into an arbitrary pattern.

[0108] 4 and 5, for example, in the D3 direction, the gap between the exposed surfaces of the multiple dummy electrodes 19 is made smaller than the gap between the exposed surfaces of the multiple internal electrodes 9. Then, the plating conditions (e.g., deposition time) are adjusted so that the deposited metal connects between the exposed surfaces of the multiple dummy electrodes 19 and does not connect between the exposed surfaces of the multiple internal electrodes 9. In this way, a first metal layer 23 having multiple extensions 23e is formed.

[0109] Also, for example, the non-exposed portion 9d described above is provided on the partial edge portion 9c of the internal electrode 9. That is, the exposed surface of the internal electrode 9 is interrupted halfway. Then, the plating conditions (e.g., deposition time) are adjusted so that the metal deposited on the exposed surface of the internal electrode 9 does not continue beyond the interruption of the exposed surface. In this way, the extension portion 23e having the interruption A3 is formed. When the non-exposed portion 9d is provided at a position where adjacent extension portions 23e are likely to be connected to each other, the non-exposed portion 9d also makes it difficult for the multiple extension portions 23e to be connected to each other.

[0110] There are various other methods for making the first metal layer 23 discontinuous. For example, the first metal layer 23 may be formed through a mask, or the first metal layer 23 may be formed and then etched through a mask. The etching may be performed by, for example, a laser process or a blast process. As can be understood from this, the first metal layer 23 does not necessarily have to cover the exposed surface (partial edge portion 9c) of the internal electrode 9, and does not necessarily have to have a pattern corresponding to the pattern of the exposed surface of the internal electrode 9. The first metal layer 23 may also be formed by a method other than electroless plating and electrolytic plating (for example, sputtering).

[0111] When the first metal layer 23 is formed by electroless plating or electrolytic plating, either may be used. For example, the first metal layer 23 may be formed by electroless plating. Also, the second metal layer 25 may be formed by electrolytic plating. By doing so, for example, the adhesive strength between the internal electrode 9 and the first metal layer 23 can be improved, while the thickness of the second metal layer 25 can be ensured in a short time and / or at low cost.

[0112] (3.3. Method of forming specific shape of internal electrode) The method for forming the unexposed portion 9d of the internal electrode 9 (partial edge portion 9c) is arbitrary.

[0113] For example, the non-exposed portion 9d may be formed by a pattern when a conductive paste that becomes the internal electrode 9 is printed on a ceramic green sheet. That is, in a plan view of the internal electrode 9, the non-exposed portion 9d may be formed by making the shape of the partial edge portion 9c have a part that is separated from the edge portion of the dielectric layer 7, rather than making the shape of the partial edge portion 9c a straight line parallel to the edge portion of the dielectric layer 7.

[0114] And / or, for example, the side surface of the effective portion 13 (dielectric layer 7 (or insulating layer 17)) may be partially removed after (or before) firing to partially expose the partial edge portion 9c. That is, the portion of the partial edge portion 9c located in the region of the side surface of the effective portion 13 where no removal has been performed may be the non-exposed portion 9d. The removal may be performed, for example, by blasting or laser processing, or a mask may be used.

[0115] As described above, barrel polishing may be performed before and / or after firing. In barrel polishing, the chip (main body 3) is housed in a barrel, and polishing is performed by rotating the barrel. Therefore, the ridges of the main body 3 are easily chamfered, and the dummy electrodes 19 are more likely to be exposed on the outer surface of the main body 3 than the internal electrodes 9. As a result, when the first metal layer 23 is formed by depositing metal on the exposed surfaces of the internal electrodes 9 and dummy electrodes 19, the first metal layer 23 is more likely to extend continuously on the dummy electrodes 19 than on the internal electrodes 9.

[0116] The method of forming the extended edge portion 9e (FIG. 8) of the internal electrode 9 is also arbitrary. For example, the extended edge portion 9e may be formed by stretching and deforming the internal electrode 9 by a blasting process after (or before) firing. The blasting process may also serve as a process for partially removing the side surface of the above-mentioned effective portion 13. The extended edge portion 9e may also be formed by thickening only the portion that will become the extended edge portion 9e when applying a conductive paste that will become the internal electrode 9.

[0117] When blasting is performed to partially remove the side surface of the effective portion 13 and / or form the extended edge portion 9e, the material of the powder to be projected and the projection direction of the powder are arbitrary. For example, the projection direction may be inclined in the direction D3 with respect to the normal to the side surface of the effective portion 13. In this case, for example, it is easy to extend and deform the edge portion of the internal electrode 9 in the direction D3. The specific magnitude of the inclination angle is arbitrary.

[0118] (3.4. Method for reducing the volume fraction of the oxide phase) As will be understood from the above explanation, in the external electrode 5, a method for making the volume ratio of the oxide phase in the first portion 5a (portion covering the effective portion 13) smaller than the volume ratio of the oxide phase in the second portion 5b (portion covering the cover 15) may be achieved by making the area ratio of the first metal layer 23 in the first portion 5a smaller than the area ratio of the first metal layer 23 in the second portion 5b. As described above, a method for making the area ratio of the first metal layer 23 in the first portion 5a smaller is achieved by forming the first metal layer 23 into an appropriate pattern.

[0119] The first oxide layer 23b is formed, for example, by exposing the first metal layer 23 to an oxidizing atmosphere after the first metal layer 23 is formed with the material of the first material layer 23a and before the second metal layer 25 is formed. At this time, the thickness of the first oxide layer 23b (from another point of view, the volume ratio of the oxide phase in the first metal layer 23) may be adjusted by adjusting the time of exposure to the oxidizing atmosphere, etc. Also, the volume ratio of the oxide phase may be adjusted by using an oxidizing agent or a reducing agent.

[0120] Similarly, the second oxide layer 25b is formed by forming the second metal layer 25 with the material of the second material layer 25a, and then exposing the second metal layer 25 to an oxidizing atmosphere. When the third metal layer 27 is provided, the thickness of the second oxide layer 25b (or, from another perspective, the volume ratio of the oxide phase in the second metal layer 25) may be adjusted by adjusting the time for which the second metal layer 25 is exposed to the oxidizing atmosphere, etc. Also, the volume ratio of the oxide phase may be adjusted by using an oxidizing agent or a reducing agent.

[0121] The method of making the volume ratio of the oxide phase in the first portion 5a smaller than the volume ratio of the oxide phase in the second portion 5b is not limited to adjusting the area ratio of the first metal layer 23. From another point of view, the first metal layer 23 does not have to extend discontinuously, and may extend without gaps.

[0122] For example, the first metal layer 23 may be formed without any gaps over the entire area of ​​the side surface of the main body portion 3 that is to be covered by the external electrode 5. Then, after the first oxide layer 23b is formed, and before the second metal layer 25 is formed, the first oxide layer 23b may be removed from part or all of the side surface of the effective portion 13 in the above-mentioned area using a reducing agent.

[0123] Also, for example, the first portion 5a may be formed after the second portion 5b is formed. Then, after the second portion 5b is formed and before the first portion 5a is formed, a heat treatment may be performed to form an oxide phase in the region of the second portion 5b on the main body portion 3 side. In this case, for example, the oxide phase of the second portion 5b improves the fixing strength of the second portion 5b to the main body portion 3.

[0124] (4. Configuration of Capacitor According to Other Embodiments) Fig. 10 is a perspective view of a capacitor 201 according to the second embodiment. In the following description, Fig. 3 according to the first embodiment may be referred to as a cross-sectional view taken along line IIIB-IIIB in Fig. 10. However, reference numerals 1 and 3 in Fig. 3 are replaced with reference numerals 201 and 203. Also, it should be noted that the specific dimensions of each part and the like in Fig. 3 do not necessarily coincide with those in Fig. 10.

[0125] Generally speaking, capacitor 201 differs from capacitor 1, which is a four-terminal type, in that it is a two-terminal type. In other words, capacitor 201 has the same basic configuration for functioning as a capacitor as capacitor 1, and is also similar to capacitor 1 in that the volume fraction of the oxide phase in first portion 5a is smaller than the volume fraction of the oxide phase in second portion 5b. More specifically, this is as follows.

[0126] 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 (as in the illustrated example) or smaller than the width (length in the D2 direction). The length (D1 direction) of the rectangular parallelepiped is, for example, greater than the width. The dimensions of the main body 203 are arbitrary. Examples of relatively small dimensions include a length of 0.4 mm or more and 3.2 mm or less, and a width and height of 0.2 mm or more and 2.5 mm or less. The external electrode 5 is generally layered and covers the longitudinal ends of the main body 203 over five faces of the rectangular parallelepiped.

[0127] The main body 203 has an effective portion 13 and a cover 15, similar to the first embodiment (see FIG. 3). The effective portion 13 is configured by alternately laminating dielectric layers 7 and internal electrodes 9. The cover 15 has at least one insulating layer 17 and at least one dummy layer 21. The dummy layer 21 includes a plurality of dummy electrodes 19.

[0128] However, the position and shape of the internal electrode 9 in plan view are different from those in the first embodiment. Specifically, for example, in plan view, the shape of the internal electrode 9 is generally a rectangle having four sides parallel to the four sides of the rectangle of the main body 203 (dielectric layer 7). Of the four sides of the internal electrode 9, two long sides and one short side are located inside the side surface of the main body 203 (not exposed). The remaining one short side is exposed from the side surface of the +D1 side or -D1 side of the main body 203 and connected to the external electrode 5 on the +D1 side or -D1 side. The internal electrodes 9 connected to different external electrodes 5 are alternately stacked. The area of ​​the internal electrode 9 that overlaps with another internal electrode 9 in plan view is the electrode main body 9a. The part extending from the electrode main body 9a to the external electrode 5 is the extraction electrode 9b.

[0129] The position and shape of the dummy electrodes 19 in a plane may be different from those in the first embodiment. Specifically, for example, in a plan view, each dummy layer 21 has two dummy electrodes 19 at both ends in the longitudinal direction of the main body portion 203. The dummy electrodes 19 are rectangular across the entire width (length in the D2 direction) of the main body portion 203, and are exposed, for example, from the side surface on the +D1 side or -D1 side of the main body portion 203 and from the side surfaces on the +D2 side and -D2 side.

[0130] As described with reference to FIG. 1 in the description of the outline of the embodiment, the requirements for the volume ratio of the oxide phase, etc., may be satisfied within the range of the length of the partial edge portion 9c of the internal electrode 9 (the target portion 5c of the external electrode 5). Therefore, with respect to the above requirements, the portions of the external electrode 5 covering the upper and lower surfaces, the +D2 side surface, and the -D1 side surface of the main body portion 203 may be ignored. In addition, when focusing on the portion of the external electrode 5 covering the side surface on the +D1 side (or the -D1 side), the portion covering the so-called side margin portion from the +D1 side (or the -D1 side) may also be ignored. The side margin portion is the portion of the main body portion 203 from the edge portion on the +D2 side (or the -D2 side) of the internal electrode 9 to the side surface on the +D2 side (or the -D2 side) of the main body portion 203.

[0131] Although not specifically shown, still another example of the capacitor configuration will be given.

[0132] The capacitor may have an exterior resin that covers the entire structure illustrated in Fig. 1 or 10, and a lead wire that is connected to the external electrode 5 and extends 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 only cover one side surface.

[0133] 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 internal electrodes 9 connected to the same external electrode 5 and facing each other may be thinner than the thickness of the dielectric layer 7 between the internal electrodes 9 connected to different external electrodes 5 and facing each other. As can be understood from this, the multiple dielectric layers 7 do not need to have the same shape and size.

[0134] Furthermore, the 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.

[0135] In the second embodiment, the side margin portion has been mentioned. The side margin portion is formed, for example, by a portion of the dielectric layer 7 that extends toward the +D2 side or the -D2 side from the internal electrode 9. However, the side margin portion may be formed by overlapping another dielectric layer on the +D2 side or the -D2 side of the laminate formed by the dielectric layer 7. From another point of view, the main body portion 203 does not need to have a laminated structure in its entirety.

[0136] 5. Working Examples 11 is a table showing the results of investigating the characteristics of a prototype capacitor according to the embodiment (more specifically, capacitor 201 according to the second embodiment). This figure shows that, for example, by making first metal layer 23 discontinuous and reducing the volume fraction of the oxide phase in first portion 5a, it is possible to improve adhesion strength and reduce ESR at the same time. More specifically, this is as follows.

[0137] In this figure, "No." is an identification number assigned to the examples and comparative examples. As will be understood from the explanation below, No. 1 to No. 6 are examples, and No. 7 is a comparative example.

[0138] "First metal layer coverage" indicates the area percentage (%) of the first metal layer 23 in the region of the side surface of the effective portion 13 where the target portion 5c of the external electrode 5 should overlap (i.e., the region where the first portion 5a should be formed), except for No. 8. "Second metal layer coverage" indicates the area percentage of the second metal layer 25 in the above region. Note that, hereinafter, for convenience, the above area percentage may be referred to simply as the area percentage on the side surface of the effective portion 13, without mentioning that the area percentage is in the region where the target portion 5c should overlap.

[0139] "Electrode peeling (number)" indicates, as a fraction, the number of samples in which the external electrodes 5 peeled off in an experiment on 100 samples. "ESR (mΩ)" indicates the measured ESR value.

[0140] 11, in all of the examples (No. 1 to No. 8), the first metal layer 23 and the second metal layer 25 were each formed over the entire area of ​​the side surface of the cover 15 that should overlap the target portion 5c of the external electrode 5. That is, in the second portion 5b, the area ratio of each layer is 100%, and from another perspective, the area ratios of the two layers are the same as each other.

[0141] 11, in the examples (No. 1 to No. 6), the area ratio of the first metal layer 23 to the side surface of the effective portion 13 is less than 100% (specifically, 40% or more and 95% or less). Also, the area ratio of the second metal layer 25 to the side surface of the effective portion 13 is 80% or more and 100% or less. From another perspective, in the first portion 5a, the area ratio of the first metal layer 23 is smaller than the area ratio of the second metal layer 25.

[0142] In the second portion 5b, the area proportions of the first metal layer 23 and the second metal layer 25 are the same, so in examples (No. 1 to No. 6) in which the area proportion of the first metal layer 23 in the first portion 5a is smaller than the area proportion of the second metal layer 25, the volume proportion of the oxide phase in the first portion 5a is smaller than the volume proportion of the oxide phase in the second portion 5b.

[0143] In No. 7 (comparative example), the area ratio of each of the first metal layer 23 and the second metal layer 25 on the side surface of the effective portion 13 is 100%. From another perspective, in the first portion 5a, as in the second portion 5b, the area ratios of the two layers are the same. Therefore, the volume ratio of the oxide phase in the first portion 5a is the same as the volume ratio of the oxide phase in the second portion 5b.

[0144] In No. 8, the volume fraction of the oxide phase is increased by subjecting the first metal layer 23 to an oxidation treatment (a treatment not performed in Nos. 1 to 7) with the intention of forming the first metal layer 23 over a relatively wide area of ​​the side surface of the effective portion 13. As a result, in No. 8, the volume fraction of the oxide phase in the first portion 5a and the second portion 5b is larger than in the other examples (Nos. 1 to 7).

[0145] The first metal layer 23 is formed by electroless plating, and the second metal layer 25 is formed by electroless plating. In No. 1 to No. 8, the second metal layers 25 are intended to have the same thickness. In No. 1 and No. 2, the area ratio of the second metal layer 25 does not reach 100% due to the small area ratio of the first metal layer 23.

[0146] In an experiment to determine whether or not electrode peeling occurs, a force of 5 N was applied to capacitor 201 mounted on a circuit board in the D2 direction (the direction along the surface of the circuit board) to check whether or not external electrode 5 peels off. ESR was determined based on impedance measurement at 1 MHz.

[0147] The specifications of the capacitor 201 used in the experiment are shown below. Length in D1 direction: 1.0mm Length in D2 and D3 directions: 0.5mm Thickness of cover 15 (D3 direction): 30μm Side margin width (D2 direction): 30μm Thickness of dielectric layer 7: 1.0 μm Number of layers of internal electrode 9: 20 layers

[0148] The number of cases where electrode peeling occurred was 0 / 100 when the coverage of the first metal layer 23 was 40% or more and 80% or less (No. 1 to No. 5), and 1 / 100 when it was 95% (No. 6). In contrast, when the coverage of the first metal layer 23 became 100%, the number of cases where electrode peeling occurred increased sharply (10 / 100). Therefore, it can be said that the effect of reducing electrode peeling is easily achieved when the coverage of the first metal layer 23 is 40% or more and 95% or less (or 40% or more and 80% or less).

[0149] In the examples, as described in the first embodiment, a non-exposed portion 9d that is not exposed from the side surface of the main body portion 203 is provided at the partial edge portion 9c of the internal electrode 9 to prevent the first metal layer 23 from being deposited, thereby reducing the area ratio of the first metal layer 23 and, in turn, reducing the volume ratio of the oxide phase (first oxide layer 23b). Therefore, when the coverage of the first metal layer 23 is reduced, the volume ratio of the oxide phase with high electrical resistivity is reduced, but the cross-sectional area of ​​the connection portion between the internal electrode 9 and the external electrode 5 is reduced. As a result, the smaller the coverage of the first metal layer 23, the higher the ESR.

[0150] However, as can be seen from a comparison with No. 8, the ESR is reduced compared to when oxidation treatment was performed. On the other hand, in No. 8, the adhesion strength of the external electrode 5 to the main body portion 203 is improved by the oxidation treatment, and the number of external electrodes 5 that peeled off is 0 / 100. Therefore, it can be said that by reducing the area ratio of the first metal layer 23 in the effective portion 13, it is possible to improve the adhesion strength without performing oxidation treatment, thereby achieving both an improvement in adhesion strength and a reduction in ESR.

[0151] An example of the coverage range of the first metal layer 23 is 40% or more and 95% or less, which is the range in the embodiment. Also, from the viewpoint of the range in which no peeling occurs, 40% or more and 80% or less is mentioned. Since the ESR roughly doubles when the coverage of the first metal layer 23 increases from 50% to 40%, from this viewpoint, 50% or more and 95% or less is mentioned. As an overlapping portion of the previous two viewpoints, 50% or more and 80% or less is mentioned.

[0152] 11 is based on the capacitor 201 according to the second embodiment and on a sample of the capacitor 201 having specific specifications. However, it is clear that within the above range, a better effect can be obtained, although it may not be the best effect.

[0153] (6. Summary of the embodiment) As described above, the capacitor 1 (or 201) has an effective portion 13, a cover 15, and an external electrode 5. The effective portion 13 has dielectric layers 7 and internal electrodes 9 that are alternately stacked. The cover 15 overlaps the effective portion 13 in the stacking direction (D3 direction) of the dielectric layers 7 and the internal electrodes 9. The external electrode 5 covers the side surfaces of the effective portion 13 and the cover 15 along the D3 direction, and is connected to a partial edge portion 9c that is a part of the outer edge of the internal electrode 9. In the portion (target portion 5c) of the external electrode 5 that extends in the D3 direction with the length of the partial edge portion 9c as its width, the portion covering the side surface of the effective portion 13 is referred to as a first portion 5a, and the portion covering the side surface of the cover 15 is referred to as a second portion 5b. In this case, the volume ratio of the oxide phase in the first portion 5a is smaller than the volume ratio of the oxide phase in the second portion 5b.

[0154] In this case, for example, as described in the overview of the embodiment, it is possible to reduce the ESR, achieve both an improvement in the adhesive strength of the external electrodes 5 and a reduction in the ESR, and / or stabilize the electrical characteristics.

[0155] The external electrode 5 may have a first metal layer 23 and a second metal layer 25. The first metal layer 23 may be in close contact with the side surface of the effective portion 13 and the side surface of the cover 15. The second metal layer 25 may overlap the first metal layer 23 with the side surface of the effective portion 13 and the side surface of the cover 15. In the first portion 5a, the first metal layer 23 may extend discontinuously. This may form a non-disposition area A1 of the first metal layer 23. The second metal layer 25 may be in close contact with the side surface of the effective portion 13 in the non-disposition area A1.

[0156] In this case, for example, according to a normal metal film forming process, since there is a high probability that the first oxide layer 23b is formed on the surface of the first metal layer 23, the volume ratio of the oxide phase in the first portion 5a can be reduced by making the first metal layer 23 discontinuous on the side surface of the effective portion 13. This provides the above-mentioned effect of reducing ESR, etc. Also, for example, by making the first metal layer 23 discontinuous, as already described, the adhesive strength between the first metal layer 23 and the second metal layer 25 can be improved. As shown with reference to the examples, it is easy to achieve both a reduction in ESR and an improvement in adhesive strength.

[0157] Each of the first metal layer 23 and the second metal layer 25 may be made of a polycrystalline body. The average grain size of the first crystal grains 23p in the first metal layer 23 may be smaller than the average grain size of the second crystal grains 25p in the second metal layer 25.

[0158] In this case, the surface area of ​​the first metal layer 23 is likely to be large compared to, for example, an embodiment in which the average grain size of the first crystal grains 23p is relatively large (such an embodiment is also included in the technology according to the present disclosure). As a result, the affinity between the first metal layer 23 and the second metal layer 25 is improved, and the bonding strength between them is likely to be improved. Meanwhile, since the average grain size of the second crystal grains 25p is relatively large, the number of grain boundaries can be reduced. As a result, for example, the probability of moisture penetrating from the outside can be reduced.

[0159] The ratio of the area of ​​the side surface of the effective portion 13 that is covered by the first metal layer 23 to the area of ​​the first region that is covered by the first portion 5a may be 50% or more and 95% or less.

[0160] In this case, for example, as described with reference to FIG. 11, it is easy to achieve both a reduction in ESR and an improvement in adhesion strength.

[0161] When the first portion 5a is viewed in the normal direction, the first metal layer 23 may have a plurality of extending portions 23e extending in a direction intersecting the stacking direction (direction D3) (direction D2 in FIG. 5) at different positions in the stacking direction (direction D3). Note that the separating portion 23f may also be regarded as a type of extending portion depending on its shape.

[0162] In this case, for example, the first metal layer 23 and the second metal layer 25 are engaged in the stacking direction, which facilitates improving the bonding strength between them in the D3 direction. Usually, the capacitor 1 (201) often faces the circuit board on which the capacitor 1 is mounted in the D3 direction, and thus there is a high probability that the capacitor 1 will be peeled off from the circuit board in the D3 direction. Therefore, by improving the bonding strength in the D3 direction, it is easy to efficiently improve the strength of the external electrode 5.

[0163] At least one of the multiple extending portions 23e may have a discontinuity A3 midway in the intersecting direction (direction D2 in FIG. 5).

[0164] In this case, for example, the first metal layer 23 and the second metal layer 25 are engaged in two directions, that is, the direction D3 and the direction intersecting the direction D3, making it easier to improve the bonding strength in various directions.

[0165] The multiple extension portions 23e may extend along the partial edge portions 9c of the multiple internal electrodes 9 so as to cover the partial edge portions 9c.

[0166] In this case, for example, while making the first metal layer 23 discontinuous, it is easy to ensure the bonding area between the first metal layer 23 and the partial edge portion 9c. As a result, for example, it is easy to achieve the effect of improving the bonding strength between the internal electrode 9 and the second metal layer 25 by reducing the average particle size of the first metal layer 23 described above. In addition, for example, the extension portion 23e can be formed by forming the first metal layer 23 on the partial edge portion 9c by electroless plating or electrolytic plating. That is, the first metal layer 23 can be simply made discontinuous.

[0167] In at least one of the multiple internal electrodes 9, the partial edge portion 9c may have a non-exposed portion 9d (FIG. 4) midway in the intersecting direction (direction D2 in FIG. 5) that is not exposed from the side surface of the effective portion 13. The extension portion 23e covering the partial edge portion 9c having the non-exposed portion 9d may have an interruption A3 at a position overlapping the non-exposed portion 9d.

[0168] In this case, for example, it is easy to ensure the bonding area between the extension portion 23e and the partial edge portion 9c while making the extension portion 23e discontinuous in its extension direction. Also, for example, the extension portion 23e having the discontinuity A3 can be formed by forming the first metal layer 23 on the partial edge portion 9c by electroless plating or electrolytic plating. That is, it is possible to easily make the extension portion 23e discontinuous in its extension direction.

[0169] The thickness of the partial edge portion 9c may be greater than the thickness of the portion of the internal electrode 9 located more inward than the partial edge portion 9c.

[0170] In this case, for example, the bonding area between the external electrode 5 (for example, the first metal layer 23) and the partial edge portion 9c is increased, so that the bonding strength between them can be improved. Also, for example, when removing the side surface of the dielectric layer 7 by blasting to expose the partial edge portion 9c from the side surface of the main body portion 3, the internal electrode 9 can be stretched and deformed to thicken the partial edge portion 9c while performing the step of exposing it, so that the likelihood of an increase in the number of processes can be reduced.

[0171] The effective portion 13 may have a rectangular shape when viewed in the stacking direction (D3 direction). The cover 15 may have four dummy electrodes 19 and an insulating layer 17. The four dummy electrodes 19 may be located at four corners of the effective portion 13 when viewed in the D3 direction. The insulating layer 17 may cover the four dummy electrodes 19 from the side opposite to the effective portion 13. The four external electrodes 5 may be fixed to the four dummy electrodes 19.

[0172] In this case, for example, the adhesive strength of the external electrode 5 to the main body portion 3 can be improved. Also, for example, when forming the first metal layer 23 by electroless plating or electrolytic plating, by depositing metal on the dummy electrode 19, it becomes easy to form the first metal layer 23 without gaps on the side surface of the cover 15. Since the dummy electrode 19 is located on a diagonal line on the rectangular main body portion 3 where the length can be easily ensured, the dummy electrode 19 can be easily separated from the electrode main body 9a. As a result, the effect of the dummy electrode 19 on the characteristics of the effective portion 13 can be easily reduced.

[0173] The technology according to the present disclosure is not limited to the above-described embodiments and may be implemented in various forms.

[0174] For example, the multilayer electronic component is not limited to a capacitor. For example, in the multilayer electronic component, some of the internal electrodes may form a capacitor, and other parts of the internal electrodes may form an inductor or resistor. The multilayer electronic component may form an appropriate circuit (for example, a resonant circuit) as a whole. Furthermore, it is sufficient that at least a part of the multilayer electronic component is formed by laminating dielectric layers and internal electrodes, and the entirety or most of the multilayer electronic component does not necessarily have to be formed of a laminate.

[0175] From the present disclosure, a concept may be extracted that does not require that the volume ratio of the oxide phase in the first portion 5a be smaller than the volume ratio of the oxide phase in the second portion 5b. For example, a concept characterized in that the first metal layer 23 extends discontinuously may be extracted, or a concept characterized in that the partial edge portion 9c of the internal electrode 9 is thicker than the inner portion of the internal electrode 9 may be extracted.

[0176] The following concepts may be extracted from this disclosure. (Concept 1) an active portion having dielectric layers and internal electrodes alternately stacked; a cover overlapping the effective portion in a lamination direction of the dielectric layers and the internal electrodes; an external electrode covering a side surface of the effective portion and the cover along the stacking direction and connected to a partial edge portion that is a part of an outer edge of the internal electrode; It has In a portion of the external electrode that extends in the stacking direction with the length of the partial edge portion as a width, a portion covering a side surface of the effective portion is referred to as a first portion, and a portion covering a side surface of the cover is referred to as a second portion. A volume ratio of an oxide phase in the first portion is smaller than a volume ratio of an oxide phase in the second portion. Multilayer electronic components. (Concept 2) The external electrode is a first metal layer in close contact with a side surface of the effective portion and a side surface of the cover; a second metal layer overlapping the first metal layer on a side surface of the effective portion and a side surface of the cover, In the first portion, The first metal layer extends discontinuously, thereby forming a non-disposed region of the first metal layer; The second metal layer is in close contact with a side surface of the effective portion in the non-disposition region. 2. The multilayer electronic component according to claim 1. (Concept 3) The first metal layer and the second metal layer are each made of a polycrystalline material, The average grain size of the crystal grains in the first metal layer is smaller than the average grain size of the crystal grains in the second metal layer. 3. The multilayer electronic component according to claim 2. (Concept 4) A ratio of an area of ​​the first metal layer covering the first region to an area of ​​the side surface of the effective portion that is covered by the first portion is 50% or more and 95% or less. 4. The multilayer electronic component according to claim 2 or 3. (Concept 5) When the first portion is viewed in a normal direction thereof, the first metal layer has a plurality of extending portions extending in a direction intersecting the stacking direction at different positions in the stacking direction. The multilayer electronic component according to any one of Concepts 2 to 4. (Concept 6) At least one of the plurality of extension portions has a discontinuity in the intersecting direction. 6. The laminated electronic component according to claim 5. (Concept 7) The plurality of extension portions extend along the partial edge portions so as to cover the partial edge portions of the plurality of internal electrodes. 7. The multilayer electronic component according to Concept 5 or 6. (Concept 8) In at least one of the plurality of internal electrodes, the partial edge portion has a non-exposed portion that is not exposed from a side surface of the effective portion in the middle in the intersecting direction, The extension portion covering the edge of the portion having the unexposed portion has a discontinuity at a position overlapping the unexposed portion. 8. The laminated electronic component according to claim 7. (Concept 9) The thickness of the partial edge portion is greater than the thickness of a portion of the internal electrode that is more inside than the partial edge portion. The multilayer electronic component according to any one of Concepts 1 to 8. (Concept 10) The effective portion has a rectangular shape when viewed in the stacking direction, The cover is four dummy electrodes located at four corners of the effective portion when viewed in the stacking direction; an insulating layer covering the four dummy electrodes from the side opposite to the effective portion, The four external electrodes are fixed to the four dummy electrodes. The multilayer electronic component according to any one of Concepts 1 to 9. [Explanation of symbols]

[0177] 1... Capacitor, 5... External electrode, 5a... First part, 5b... Second part, 7... Dielectric layer, 9... Internal electrode, 9c... Partial edge.

Claims

1. an active portion having dielectric layers and internal electrodes alternately stacked; a cover overlapping the effective portion in a lamination direction of the dielectric layers and the internal electrodes; an external electrode covering a side surface of the effective portion and the cover along the stacking direction and connected to a partial edge portion that is a part of an outer edge of the internal electrode; It has The external electrode is a first metal layer made of a polycrystalline material and in close contact with a side surface of the effective portion and a side surface of the cover; a second metal layer that is made of a polycrystalline body having a larger average grain size than the first metal layer and that overlaps the first metal layer with a side surface of the effective portion and a side surface of the cover, In a portion of the external electrode that extends in the stacking direction with a width equal to the length of the partial edge portion, a portion covering a side surface of the effective portion is referred to as a first portion, and a portion covering a side surface of the cover is referred to as a second portion, an area ratio of the first metal layer in the first portion is smaller than an area ratio of the first metal layer in the second portion. Multilayer electronic components.

2. In the first portion, The first metal layer extends discontinuously, thereby forming a non-disposed region of the first metal layer; The second metal layer is in close contact with a side surface of the effective portion in the non-disposition region. The multilayer electronic component according to claim 1 .

3. The first metal layer is A material layer; and an oxide layer covering the material layer, the oxide layer being made of an oxide of the material that constitutes the material layer. The multilayer electronic component according to claim 1 or 2.

4. A ratio of an area of ​​the first metal layer covering the first region to an area of ​​the side surface of the effective portion that is covered by the first portion is 50% or more and 95% or less. The multilayer electronic component according to claim 1 .

5. When the first portion is viewed in a normal direction thereof, the first metal layer has a plurality of extending portions extending in a direction intersecting the stacking direction at different positions in the stacking direction. The multilayer electronic component according to claim 1 .

6. At least one of the plurality of extension portions has a discontinuity midway in the intersecting direction. The multilayer electronic component according to claim 5 .

7. The plurality of extension portions extend along the partial edge portions so as to cover the partial edge portions of the plurality of internal electrodes. The multilayer electronic component according to claim 5 .

8. In at least one of the plurality of internal electrodes, the partial edge portion has a non-exposed portion that is not exposed from a side surface of the effective portion in the middle in the intersecting direction, The extension portion covering the edge of the portion having the unexposed portion has a discontinuity at a position overlapping the unexposed portion. The multilayer electronic component according to claim 7 .

9. The thickness of the partial edge portion is greater than the thickness of a portion of the internal electrode that is more inside than the partial edge portion. The multilayer electronic component according to claim 1 .

10. The effective portion has a rectangular shape when viewed in the stacking direction, The cover is four dummy electrodes located at four corners of the effective portion when viewed in the stacking direction; an insulating layer covering the four dummy electrodes from the side opposite to the effective portion, The four external electrodes are fixed to the four dummy electrodes. The multilayer electronic component according to claim 1 .

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