Multilayer electronic components

Abstract

In this laminated electronic component, an effective portion has a dielectric layer and an internal electrode which are alternately laminated in the lamination direction. A cover overlaps the effective portion from a first side in the lamination direction. A base electrode overlaps the cover from the first side. An external electrode overlaps the base electrode from the first side. The base electrode and the external electrode are fixed by sharing a diffusion layer in which a material of the base electrode and a material of the external electrode are mixed with each other.

Description

Technical Field

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

Background Art

[0002] As a multilayer electronic component, for example, a multilayer ceramic capacitor is known (for example, Patent Documents 1 and 2 below). The multilayer ceramic capacitor has, for example, a main body portion that directly functions as a capacitor, and an external electrode for mounting the capacitor on a circuit board or the like. The main body portion has dielectric layers and flat internal electrodes that are alternately laminated. In Patent Documents 1 and 2, a base electrode that constitutes the surface of the main body portion is provided, and a metal layer is deposited on the base electrode by plating, thereby forming an external electrode.

Prior Art Documents

Patent Documents

[0006] The embodiments relating to this disclosure will be described below with reference to the drawings. The figures used in the following description are schematic. Therefore, for example, the dimensional ratios on the drawings do not necessarily match those of reality. Also, the dimensional ratios may not match between drawings. Certain shapes and / or dimensions may be exaggerated, or details may be omitted. However, the above does not negate the fact that the actual shape and / or dimensions may be as shown in the drawings, or that the characteristics of the shape and / or dimensions may be extracted from the drawings.

[0007] Regarding aspects described relatively later, only the differences from aspects described relatively earlier will be mentioned. Unless otherwise specified, matters may be treated the same as those described earlier, or inferred from those aspects. For convenience, the same symbols may be used for corresponding components in different aspects, even if there are differences.

[0008] In the following explanation, when we refer to a "rectangle" (or rectangular shape), "square" (or square shape), and "rectangle" (or rectangular shape), the corners may be chamfered by curved surfaces, etc., as long as the above concept of shape holds true. For example, the 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 (errors). The same applies to other polygons, etc.

[0009] (Summary of the embodiment) Figure 1 is a perspective view showing a capacitor 1 (an example of a multilayer electronic component) according to the first embodiment. For convenience, Figure 1 and other figures described later are labeled with a Cartesian coordinate system D1D2D3. The capacitor 1 may be used with either the top or bottom facing upwards. However, in the description of the embodiment, for convenience, the +D3 side may be considered the top, and terms such as top surface and bottom surface may be used.

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

[0011] Figure 3 is a cross-sectional view taken along line III-III in Figure 1. Note that Figure 3 shows the D1D3 cross-section where the external electrode 5 on the +D2 side is cut. However, the D1D3 cross-section where the external electrode 5 on the -D2 side is cut, the D2D3 cross-section where the external electrode 5 on the -D1 side is cut, and the D2D3 cross-section where the external electrode 5 on the +D1 side is cut are basically the same. In the description of the embodiment, for convenience, the terms D1, D2, and D3 may be used to describe the positional relationships between components, etc., assuming the cross-section shown in Figure 3, without further explanation.

[0012] The main body 3 includes, for example, an effective section 11, two covers 13 that overlap the upper and lower surfaces of the effective section 11, and a base layer 15 that overlaps the surface of each cover 13 opposite to the effective section 11. The effective section 11 has a plurality of alternatingly overlapping dielectric layers 7 and a plurality of internal electrodes 9. The plurality of internal electrodes 9 include a plurality of first internal electrodes 9A and a plurality of second internal electrodes 9B. Each base layer 15 has, for example, four base electrodes 16 at positions corresponding to the positions of four external electrodes 5. The external electrodes 5 overlap the base electrodes 16.

[0013] The active portion 11 directly performs the function of a capacitor. The cover 13 contributes, for example, to the protection and strength improvement of the main body 3. The base electrode 16 contributes, for example, to the deposition of the metal that will become the external electrode 5 by a plating method, and / or to the adhesion force of the external electrode 5 to the main body 3.

[0014] The lower part of Figure 3 shows an enlarged view of the boundary between the base electrode 16 and the external electrode 5. The external diffusion layer 5a is formed by the diffusion of the material of the base electrode 16 (e.g., metal) into the external electrode 5. The base diffusion layer 16a is formed by the diffusion of the material of the external electrode 5 (e.g., metal) into the base electrode 16. The diffusion layer 21 is formed by the external diffusion layer 5a and the base diffusion layer 16a. In other words, the base electrode 16 and the external electrode 5 share a diffusion layer 21 in which the materials of the base electrode 16 and the materials of the external electrode 5 are mixed together, thereby fixing them to each other.

[0015] The presence of the diffusion layer 21 increases the adhesion force of the external electrode 5 to the base electrode 16. Consequently, the likelihood of the external electrode 5 peeling off from the main body 3 is reduced. Note that heating to an appropriate temperature or higher is necessary to form the diffusion layer 21; simply depositing a metal material on the base electrode 16 will not form the diffusion layer 21.

[0016] Note that the above-described effects do not necessarily have to be achieved. Also, technical ideas from viewpoints different from the above may be extracted from the present disclosure. For example, a technical idea related to the relative relationship between the lengths Li and Ld described later may be extracted. In this case, for example, diffusion between the base electrode 16 and the external electrode 5 may not occur.

[0017] The above is the outline of the embodiment. Specifically, the embodiment will be described in the following order, generally. 1. Configuration of the capacitor according to the first embodiment (Figs. 1 to 3) 1.1. Overall configuration 1.2. Active part 1.3. Cover 1.4. Base electrode 1.5. External electrode 2. Diffusion layer 2.1. Material of the diffusion layer 2.2. Thickness of the diffusion layer 3. Method for manufacturing the capacitor 4. Configuration of the capacitor according to other embodiments 4.1. Second embodiment (Fig. 4) etc. 4.2. Third embodiment (Fig. 6) 5. Examples 6. Summary of the embodiment

[0018] (1. Configuration of the capacitor according to the first embodiment) (1.1. Overall configuration) The capacitor 1 shown in Fig. 1 is configured as, for example, a chip-type component to be surface-mounted. Specifically, for example, the capacitor 1 is arranged with the surface on the -D3 side or the +D3 side facing a circuit board (not shown). Then, the four pads of the circuit board and the four external electrodes 5 are joined by a conductive joining material (e.g., solder) (not shown), respectively, so that the capacitor is mounted on the circuit board.

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

[0020] 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 illustration) or a rectangle (excluding squares; the same applies hereinafter) when viewed from above. In the description of the embodiment, for convenience, the description may assume a square shape unless otherwise specified.

[0021] The specific dimensions of the main body 3 (or capacitor 1) are arbitrary. For example, when capacitor 1 is relatively small, the lengths in the D1 and D2 directions of the main body 3 (or capacitor 1) may be between 0.030 mm and 0.200 mm. When the length in the D1 direction is L and the length in the D2 direction is W, L / W may be between 0.5 and 2.0. The thickness in the D3 direction may be between 0.030 mm and 0.200 mm. If the surface of the main body 3 is not planar, for example, the maximum values ​​of the various dimensions may satisfy the above ranges (the same applies to the various dimensions of other components, unless contradictions arise).

[0022] Note that the example dimensions of each component described later are for the case where capacitor 1 is relatively small, unless otherwise specified. Therefore, larger (or smaller) dimensions than those exemplified may be used.

[0023] Multiple components of the same type (e.g., 5, 7, 9, 13, 15, 16, 17, 19, or 20, etc.) may be provided with the same (or corresponding) shape, size, material, and position, etc., unless otherwise specified and unless contradictions arise. Therefore, unless otherwise specified and unless contradictions arise, the description of one component may be considered common to multiple components of the same type.

[0024] A single layered (membrane) component (e.g., 5, 7, 9, 15, 17, or 19, etc.) may be composed entirely of one material. However, it may also be composed of layers made of different materials stacked on top of each other.

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

[0026] The dielectric layer 7 is basically a layered structure with a constant thickness (at least between the internal electrodes 9). The thickness of the dielectric layer 7 may be set appropriately according to the characteristics required of the capacitor 1. As an example of a relatively thin thickness, the thickness between adjacent internal electrodes 9 (between the first internal electrode 9A and the second internal electrode 9B) may be 0.1 μm or more or 0.5 μm or more, and may also be 3.0 μm or less, 2.0 μm or less, or 1.0 μm or less. The above lower and upper limits may be combined in any way. The shape and dimensions of the dielectric layer 7 in plan view are basically the same as the shape and dimensions of the effective portion 11 in plan view. The material of the dielectric layer is, for example, ceramics, and the specific type is also arbitrary. The number of layers of dielectric layer 7 (internal electrodes 9) is arbitrary. For example, it may be 10 to 30 layers.

[0027] The internal electrode 9 is layered and has a certain thickness. The thickness of the internal electrode 9 is arbitrary; for example, it may be thinner than, the same as, or thicker than the thickness of the region between the internal electrodes 9 in the dielectric layer 7. As an example of a relatively thin thickness, the thickness of the internal electrode 9 may be 0.3 μm or more or 0.5 μm or more, or it may be 3.0 μm or less, 2.0 μm or less, or 1.0 μm or less. The above lower and upper limits may be combined in any way.

[0028] The material of the internal electrode 9 is, for example, a metal. The specific type of metal is arbitrary. For example, all or the main component (for example, 60% by mass or more of the component; the same applies to other materials hereinafter) of the metal (or material of the internal electrode 9) of the internal electrode 9 is a base metal (for example, Ni and / or Cu). In addition to metal, the internal electrode 9 may also contain ceramics. These ceramics may be the same material (hereinafter, for convenience, the ceramics in the electrode will be referred to as the same material) when the internal electrode 9 is constructed by a conductive paste that is fired together with the ceramic green sheet that becomes the dielectric layer 7. The same material may be, for example, the same component (for example, the main component) of the dielectric layer 7. As an example, the same material may be barium titanate. The content of the same material in the internal electrode 9 (after firing) is arbitrary, and may be, for example, 1% by mass or more and 30% by mass or less.

[0029] Figure 2 is an exploded perspective view of capacitor 1. Figure 2 is a schematic representation for understanding the shape and relative position of internal electrodes 9, etc. Therefore, in Figure 2, various layers are shown in fewer numbers compared to Figure 3.

[0030] The internal electrode 9, for example, in a plan view, has a rectangular (square in the illustrated example) electrode body 9a and a pair of leading 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 of the effective portion 11. The pair of leading 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 3.

[0031] The first internal electrode 9A and the second internal electrode 9B face each other with the dielectric layer 7 in between. The pair of lead electrodes 9b of the first internal electrode 9A and the pair of lead electrodes 9b of the second internal electrode 9B are located on opposite diagonals in a planar perspective view. They are connected to two different pairs of external electrodes 5.

[0032] The dimensions of the electrode body 9a and the lead electrode 9b are arbitrary. For example, the length of one side of the dielectric layer 7 of the lead electrode 9b (the length of one side of the edge) is approximately the same as the length of the external electrode 5 along that same side.

[0033] (1.3. Cover) The cover 13 shown in Figure 3 is, for example, a layered structure with a shape and dimensions that overlap the effective portion 11 without excess or deficiency. The thickness of the cover 13 is approximately constant in both the area where the base electrode 16 is placed and the area where it is not placed. The ratio of the thickness of the cover 13 to the thickness of the main body 3 may be approximately the inverse of the ratio of the thickness of the effective portion 11 to the thickness of the main body 3 (as described above). For example, in an embodiment in which covers 13 are provided on both sides in the D3 direction, the thickness of one cover 13 may be, for example, 5% or more, 10% or more, or 15% or more of the thickness of the main body 3, and may also be 35% or less, 30% or less, or 25% or less. The above lower and upper limits may be combined in any way. The thickness of the cover 13 is, for example, the thickness in the area that overlaps the internal electrode 9 and does not overlap the base electrode 16 (is not crushed by the base electrode 16).

[0034] Each cover 13 has, for example, multiple (two in the example of Figure 3) insulating layers 17 and at least one (one in the example of Figure 3) dummy layer 19 located between the multiple insulating layers 17. Each dummy layer 19 has, for example, four dummy electrodes 20 at positions corresponding to the positions of the four external electrodes 5. The dummy electrodes 20 contribute, for example, to reinforce the cover 13 and / or to improving the connection strength between the main body 3 and the external electrodes 5, and also function as a base in embodiments in which the external electrodes 5 are formed by a plating method. Unlike the illustrated example, the cover 13 may have only one or more insulating layers 17 (it may not have any dummy layers 19).

[0035] The insulating layer 17 and the dummy layer 19 overlap alternately, one at a time. In other words, a dummy layer 19 is provided at the boundary of all insulating layers 17. Unlike the illustrated example, the dummy layer 19 may be provided at only some of the multiple boundaries. For example, one or more boundaries relatively close to the effective part 11 may not have a dummy layer 19, while one or more boundaries relatively far from the effective part 11 may have a dummy layer 19. However, in such a case, two or more insulating layers 17 that are in close contact with each other without an intervening dummy layer 19 may be treated as a single insulating layer 17.

[0036] The insulating layer 17 is layered and has a generally constant thickness, except for variations in thickness due to differences in overlap with the conductive layers (9, 15, and 19). The planar shape of the insulating layer 17 is, for example, basically the same as the planar shape of the dielectric layer 7. The material of the insulating layer 17 is arbitrary. For example, the material of the insulating layer 17 may be the same as or different from the material of the dielectric layer 7. Also, the material of the insulating layer 17 may be, for example, ceramics or a material other than ceramics.

[0037] The thickness of the insulating layer 17 is arbitrary. For example, the thickness of the insulating layer 17 may be thicker than the thickness of the dielectric layer 7 (in both cases, the thickness between conductor layers, or the thickness of regions not overlapping with conductor layers; the same applies hereafter in this paragraph), the same as, or thinner than the thickness of the dielectric layer 7. For example, the thickness of the insulating layer 17 may be 2 times or more, 3 times or more, or 5 times or more the thickness of the dielectric layer 7, or 20 times or less, 10 times or less, or 5 times or less. The above lower and upper limits may be combined in any way. Also, for example, the thickness of the insulating layer 17 may be 1.0 μm or more, or 2.0 μm or more, or 10.0 μm or 5.0 μm or less. The above lower and upper limits may be combined in any way. Note that the insulating layer overlapping the uppermost internal electrode 9 may be considered as the insulating layer 17, not the dielectric layer 7, regardless of its material and thickness. The same applies to the insulating layer that overlaps the inner electrode 9 in the lowest layer.

[0038] The dummy electrode 20 is, for example, layered, with a basically constant thickness. The material of the dummy electrode 20 is, for example, a metal. The specific type of metal is arbitrary. For example, all or the main component of the metal (or material of the dummy electrode 20) of the dummy electrode 20 is a base metal (e.g., Ni and / or Cu). The dummy electrode 20 may also contain ceramics, similar to the internal electrode 9. The description of ceramics in the internal electrode 9 may be applied to the ceramics in the dummy electrode 20 by replacing the terms "internal electrode 9" and "dielectric layer 7" with the terms "dummy electrode 20" and "insulating layer 17," respectively. The material of the dummy electrode 20 may be the same as or different from the material of the internal electrode 9.

[0039] In a plan view, the position, shape, and dimensions of the dummy electrode 20 are arbitrary. In the examples of Figures 2 and 3, the position, shape, and dimensions of the dummy electrode 20 are such that, in a plan view, they roughly overlap with the external electrode 5 without excess or deficiency (however, the external electrode 5 is slightly wider). The dummy electrode 20 is exposed, for example, on the side of the main body 3. This exposed portion is fixed to the external electrode 5.

[0040] The thickness of the dummy electrode 20 is arbitrary. For example, the thickness of the dummy electrode 20 may be thicker than the thickness of the internal electrode 9 (as shown in the illustration), the same as, or thinner than. For example, the thickness of the dummy electrode 20 may be 1 or more, 1.5 or more, or 2 or more than the thickness of the internal electrode 9, or 10 or less, 5 or less, or 2 or less. The above lower and upper limits may be combined in any way. Also, for example, the thickness of the dummy electrode 20 may be 0.3 μm or more, 0.5 μm or more, 1.0 μm or more, or 2.0 μm or more, or 10.0 μm or less, 5.0 μm or less, 3.0 μm or less, or 2.0 μm or less. The above lower and upper limits may be combined in any way. Also, the thickness of the dummy electrode 20 may be thinner than the thickness of the insulating layer 17 (as shown in the illustration), the same as, or thicker than.

[0041] (1.4. Underlay electrode) The base electrode 16 is, for example, a layer having a basically constant thickness. The material of the base electrode 16 is, for example, a metal. The specific type of metal is arbitrary. For example, all or the main component of the metal (or material of the base electrode 16) of the base electrode 16 is a base metal (e.g., Ni and / or Cu). The base electrode 16 may also contain ceramics, similar to the internal electrode 9 and the dummy electrode 20. The description of ceramics in the internal electrode 9 may be applied to the ceramics in the base electrode 16 by replacing the terms "internal electrode 9" and "dielectric layer 7" with the terms "base electrode 16" and "insulating layer 17," respectively. The material of the base electrode 16 may be the same as or different from the material of the internal electrode 9 and / or the material of the dummy electrode 20.

[0042] In a plan view, the position, shape, and dimensions of the base electrode 16 are arbitrary. In the examples in Figures 2 and 3, the position, shape, and dimensions of the base electrode 16 are such that, in a plan perspective view, they roughly overlap with the external electrode 5 without excess or deficiency (however, the external electrode 5 is slightly wider).

[0043] The thickness of the base electrode 16 is arbitrary. For example, the thickness of the base electrode 16 may be thicker than the thickness of the internal electrode 9 and / or the dummy electrode 20 (as shown in the illustration), the same as, or thinner than. For example, the thickness of the base electrode 16 may be 2 times or more, 3 times or more, or 5 times or more the thickness of the internal electrode 9 and / or the dummy electrode 20, or 20 times or less, 10 times or less, or 5 times or less. The above lower and upper limits may be combined in any way. Also, for example, the thickness of the base electrode 16 may be 2.0 μm or more, 3.0 μm or more, or 5.0 μm or more, or 20.0 μm or less, 10.0 μm or less, or 5.0 μm or less. The above lower and upper limits may be combined in any way. Also, the thickness of the base electrode 16 may be thinner than, the same as, or thicker than the thickness of the insulating layer 17 (as shown in the illustration).

[0044] (1.5.External electrode) The external electrode 5 is, for example, layered, with a basically constant thickness. The material of the external electrode 5 is, for example, a metal. The specific type of metal is arbitrary. For example, all or the main component of the metal (or material of the external electrode 5) of the external electrode 5 is a base metal (e.g., Ni and / or Cu). The external electrode 5 may or may not contain nonmetals (e.g., ceramics). In the description of the embodiments, the latter will be taken as an example. Also, the external electrode 5 may be constructed by laminating different materials as needed. For example, the external electrode 5 may be constructed by laminating Cu, Ni, and Sn from the side of the base electrode 16. The material of the external electrode 5, the material of the internal electrode 9, the material of the dummy electrode 20, and / or the material of the base electrode 16 may be the same or different. However, before diffusion bonding, the material of at least the layer of the external electrode 5 that is in contact with the base electrode 16 is different from the material of the layer of the base electrode 16 that is in contact with the external electrode 5.

[0045] As shown in Figure 1, the external electrode 5 covers four surfaces (top, bottom, and two sides) of the main body 3, for example, at the corners in a plan view of the main body 3. This allows one external electrode 5 to be connected to one lead electrode 9b on two sides of the main body 3, and also allows surface mounting of the capacitor 1 on either the top or bottom surface. The shape and dimensions of the portions of the external electrode 5 on each surface are arbitrary. The planar shape of the portion of the external electrode 5 located on the top or bottom surface of the main body 3 is, for example, rectangular (square in the illustrated example). 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 top or bottom surface.

[0046] The thickness of the external electrode 5 is arbitrary. For example, the thickness of the external electrode 5 may be greater than the thickness of the internal electrode 9, the dummy electrode 20, and the base electrode 16. For example, the thickness of the external electrode 5 may be 1.2 times or more, 2 times or more, or 3 times or more, or 10 times or less, 5 times or less, or 3 times or less, than the thickness of the base electrode 16. The above lower and upper limits may be combined in any way. Also, for example, the thickness of the external electrode 5 may be 3 μm or more, 5 μm or more, or 10 μm or more, or 30 μm or less, 20 μm or less, or 10 μm or less. The above lower and upper limits may be combined in any way.

[0047] (2. Diffusion layer) (2.1. Materials for the diffusion layer) The main component of the base electrode 16 (or its metal component; the same applies hereinafter) shall be referred to as the first metal. The main component of the external electrode 5 shall be referred to as the second metal. The first metal and the second metal are different from each other. For convenience, without further explanation, the first metal may be used as an example of the material of the base electrode 16 that diffuses into the external electrode 5, and the second metal may be used as an example of the material of the external electrode 5 that diffuses into the base electrode 16. In the following explanation, unless contradictions arise, the term "first metal" may be substituted for the term "material of the base electrode 16," and the term "second metal" may be substituted for the term "material of the external electrode 5."

[0048] Furthermore, for convenience, the following explanation may focus solely on metals when describing diffusion, without further explanation. For example, the mass percentages shown below may be considered as values ​​that ignore the co-material (metals and nonmetals contained in the co-material) of the base electrode 16, unless contradictions arise. However, unless contradictions arise, the mass percentages may also be considered as values ​​that take into account the co-material (or, from another perspective, all components of the base electrode 16). Also, exceptionally, the atomic percentages described below include all atoms contained in the base electrode 16 or the external electrode 5. For example, the denominator (or numerator) of the atomic percentage in the base electrode 16 includes the amount of elements contained in the co-material.

[0049] The portion of the base electrode 16 other than the base diffusion layer 16a shall be referred to as the base non-diffusing layer 16b. The portion of the external electrode 5 other than the external diffusion layer 5a shall be referred to as the external non-diffusing layer 5b. The boundary between the base electrode 16 and the external electrode 5 shall be referred to as the interface BS.

[0050] The non-diffusing base layer 16b is not required. In other words, the second metal of the external electrode 5 may diffuse throughout the entire thickness of the base electrode 16, so that the entire base electrode 16 becomes the diffusing base layer 16a. The same applies to the external non-diffusing layer 5b, although the non-diffusing base layer 16b has been described.

[0051] Before the first metal of the base electrode 16 diffuses into the external electrode 5, the external diffusion layer 5a and the external non-diffusion layer 5b are a single metal layer made of the same material. The external electrode 5 may be composed of multiple metal layers stacked together before the above diffusion. However, for convenience, in the following explanation, unless otherwise specified, the single metal layer described above may be referred to as the external electrode 5. The same applies to the base electrode 16, as described for the external electrode 5.

[0052] When another metal layer exists on the opposite side of the outer non-diffusing layer 5b from the underlying electrode 16, the material of the other metal layer may diffuse into the outer non-diffusing layer 5b. For convenience, such diffusion will not be described in the following explanation. Unless otherwise specified, and unless contradictions arise, the explanation of the components of the outer non-diffusing layer 5b in the following explanation may be valid in the manner in which such diffusion occurs and / or does not occur. The same applies to the underlying electrode 16, although the outer electrode 5 has been described.

[0053] As previously described, components making up 60% by mass or more are referred to as the main component, and the main component of the base electrode 16 is referred to as the first metal. Whether or not any component makes up 60% by mass or more can be determined, for example, based on the material of the base electrode 16 before diffusion occurs. Alternatively, when determining the main component of the base electrode 16 based on the base electrode 16 after diffusion, it can be determined, for example, in the region of the thickness of the base electrode 16 in which the second metal has not diffused. As can be understood from the explanation described later, this region may be, for example, a region of the base non-diffusing layer 16b that is further away from the external electrode 5 than the base diffusion layer 16a.

[0054] In embodiments where there is no region in the base electrode 16 where the diffusion of the second metal as described above has not occurred, for example, it may be determined whether or not each component is 60% by mass or more in the region (or the region where it is expected to be) with the lowest diffusion amount (e.g., atomic %) of the second metal. A region where the second metal has not diffused can also be considered an example of a region with the lowest diffusion amount of the second metal. In situations where the second metal is not specified, for example, the region furthest from the external electrode 5 (or the central region of the thickness of the base electrode 16 depending on the configuration on the opposite side of the external electrode 5) may be used as the region where the diffusion amount of the second metal is expected to be lowest.

[0055] The main components of the base electrode 16 have been described, and the same applies to the main components of the external electrode 5. Furthermore, in the following explanation, terms such as "base electrode 16 before diffusion" may be replaced with terms such as "the region of the base electrode 16 in which the diffusion amount of the second metal is smallest," unless such a contradiction arises. Similarly, terms such as "external electrode 5 before diffusion" may be replaced with terms such as "the region of the external electrode 5 in which the diffusion amount of the first metal is smallest," unless such a contradiction arises.

[0056] Specific embodiments of the diffusion layer 21 include, for example, the following first and second embodiments.

[0057] In the first embodiment, the base electrode 16 and the external electrode 5 before diffusion have different pure metals. The elements of these pure metals are the first metal and the second metal. The diffusion layer 21 is an alloy of the first metal and the second metal. Specifically, the first metal (base electrode 16) is Ni, the second metal (external electrode 5) is Cu, and the material of the diffusion layer 21 is a Ni-Cu alloy and / or a Cu-Ni alloy.

[0058] It should be noted that even in the case of pure metals, it is inevitable that impurities may be present. These impurities are metals and / or nonmetals. The amount of these impurities may be taken into consideration when determining whether the requirements for the main component, such as 60% by mass or 12.5 atomic% (described later), are met. The treatment of impurities in non-pure metals is the same.

[0059] In the second embodiment, at least one of the base electrode 16 and the external electrode 5 before diffusion is an alloy. However, the main components (first metal and second metal) of the material of the base electrode 16 and the material of the external electrode 5 are different from each other. The diffusion layer 21 is an alloy containing the main components of both. To give a specific example, the base electrode 16 is made of a Ni alloy (the first metal is Ni), the external electrode 5 is made of a Cu alloy (the second metal is Cu), and the material of the diffusion layer 21 is a Ni-Cu alloy and / or a Cu-Ni alloy.

[0060] In the specific example relating to the second embodiment described above, examples of minor components (for example, components making up 40% by mass or less) contained in the Ni alloy (the metal constituting the base electrode 16 before diffusion) include Cr, Mo, Fe, Co, and Cu. Examples of minor components contained in the Cu alloy (the metal constituting the external electrode 5 before diffusion) include Sn, Zn, Pb, Fe, Mn, Al, Be, W, and Ni.

[0061] As can be understood from the above examples, in the second embodiment, the base electrode 16 (e.g., Ni alloy) before diffusion may contain the main component (second metal: e.g., Cu) of the external electrode 5 before diffusion as a minor component. However, when adopting the definition of the diffusion layer 21 described later, the embodiment in which the presence of the base diffusion layer 16a can be identified is when the amount of the second metal contained as a minor component in the base electrode 16 before diffusion is less than 12.5 atomic percent. The same applies to the minor components of the external electrode 5, as described for the minor components of the base electrode 16.

[0062] In the above specific example relating to the second embodiment, the main components (the first metal and the second metal, respectively) may, for example, contain one element and / or be considered to have one element as the main component. However, as long as the elements contained in the first metal and the second metal are not common, two or more elements may be the main components and / or two or more elements may be considered to have two or more elements as the main components. For example, consider an embodiment in which the base electrode 16 before diffusion is Ni (pure metal) and the external electrode 5 before diffusion is a Cu-Al alloy. In this case, the requirement of 60 mass% or more of Cu alone may be satisfied in the external electrode 5, or the requirement of 60 mass% or more of Cu and Al combined may be satisfied. In the former case, only Cu may be considered to have the main component of the external electrode 5, or both Cu and Al may be considered to have the main component.

[0063] The state of the alloy in the diffusion layer 21 is arbitrary. For example, the alloy may be mainly a solid solution, eutectic, or intermetallic compound. For example, Ni-Cu alloys or Cu-Ni alloys are usually solid solutions. In addition, grain boundary diffusion and / or volume diffusion may occur in the diffusion layer 21.

[0064] (2.2. Thickness of the diffusion layer) The thickness t1 of the base diffusion layer 16a and the thickness t2 of the outer diffusion layer 5a are arbitrary. For example, the thickness t1 may be 1.0 μm or more and 3.5 μm or less, and / or 0.25 or more and 0.88 or less relative to the thickness of the base electrode 16. The thickness t2 may be 1.0 μm or more and 3.5 μm or less, and / or 0.10 or more and 0.58 or less relative to the thickness of the outer electrode 5. Furthermore, the thicknesses t1 and t2 may be the same or different. In the latter case, the degree of difference is also arbitrary. For example, the thickness t1 may be 2 / 3 or more and 3 / 2 or less of the thickness t2, or 6 / 7 or more and 7 / 6 or less. In the embodiments described later, it will be shown that a certain degree of adhesion force of the outer electrode 5 is ensured in the case of the above thicknesses.

[0065] Here, in the region of the base electrode 16 that is relatively far from the external electrode 5, for example, the amount of diffusion of the main component (second metal) of the external electrode 5 gradually decreases as you move away from the external electrode 5. Therefore, the boundary line of the base diffusion layer 16a on the opposite side of the external electrode 5 (the boundary line between the base diffusion layer 16a and the base non-diffusing layer 16b) used to determine the thickness t1 may be, for example, the position where the second metal is present at 12.5 atomic percent. In other words, the base diffusion layer 16a may be defined as the region containing the second metal at 12.5 atomic percent or more. The same applies to the boundary line used to determine the thickness t2. That is, the external diffusion layer 5a may be defined as the region containing the main component (first metal) of the base electrode 16 at 12.5 atomic percent or more.

[0066] The value 12.5 atomic percent is the value used to determine thicknesses t1 and t2 in the examples described later. Here, the diffusion layer is defined using the value 12.5 atomic percent for the purpose of determining thicknesses t1 and / or t2. However, if it is not necessary to determine thicknesses t1 and / or t2, the diffusion layer does not need to be defined in this way. However, in situations other than when determining thicknesses t1 and / or t2, the above definition may be used as needed.

[0067] The boundary line between the underlying diffusion layer 16a and the underlying non-diffusing layer 16b may be identified with the precision necessary to determine, for example, the thickness of the diffusion layer 21. For example, since the significant digits of the range of thicknesses t1 and t2 exemplified in this disclosure (as described above) are 0.1 μm, the boundary line may be identified with an precision of 0.1 μm (or even higher precision). Furthermore, the atomic percentage may be calculated, for example, in a unit area where the boundary line can be identified with the precision described above. For example, when determining the boundary line with a precision of 0.1 μm, the above unit area is, for example, 0.01 μm. 2 (Or an even smaller area may be used.) The shape of each unit area may be, for example, a square (e.g., a square of 0.1 μm × 0.1 μm).

[0068] The boundary line where the diffusion rate is 12.5 atomic percent is not necessarily straight, but may have undulations (wavy shape). If the undulations affect the determination of whether thicknesses t1 and / or t2 fall within the range exemplified in the embodiment, then thicknesses t1 and t2 may be determined, for example, based on the average height of the boundary line. In the examples described later, the average height is also used.

[0069] In the examples shown in Figures 1 to 3, the base electrodes 16 are located at the four corners of both the upper and lower surfaces of the main body 3, with a total of eight base electrodes 16 provided. The above-mentioned thickness ranges t1 and / or t2 do not need to be satisfied for all of the multiple (eight) base electrodes 16. For example, the above thickness range may be satisfied for only one base electrode 16. Of course, the above thickness range may be satisfied for all of the base electrodes 16.

[0070] When considering each base electrode 16, the above thickness range does not necessarily have to be filled over the entire base electrode 16. For example, it may be filled only over 50% or 80% of the area of ​​the base electrode 16. Of course, the above thickness range may be filled over the entire base electrode 16. However, even in this case, the unique portion may be excluded. An example of a unique portion is the edge of the base electrode 16. Since the edge is covered by the external electrode 5 not only on the top surface but also on the sides, the diffusion layer 21 is basically formed over the entire thickness.

[0071] Whether the thickness range exemplified in the embodiment is satisfied over a certain area of ​​each base electrode 16 may be determined, for example, based on a predetermined number (e.g., 3, 5, or 10) of D1D3 cross-sectional images set at equal distances from the length of the base electrode 16 in the D2 direction. If it is difficult to extract multiple cross-sectional images from a single capacitor 1, multiple cross-sectional images may be extracted from multiple capacitors 1 of the same type.

[0072] Cross-sectional images may be acquired, for example, by a Scanning Electron Microscope (SEM) at an appropriate magnification. SEMs may have a function to color-code regions within the image according to the atomic percentage value of a specific element. This function may be used to identify and measure the dimensions of regions where the first or second metal is present in 12.5 atomic percent or more.

[0073] Even when the materials of the base electrode 16 and the external electrode 5 are mixed, an interface BS can be observed in the SEM image. This is because a cavity exists between the two materials, and / or the crystal grain sizes of the two materials are different. The interface BS, like the 12.5% ​​atomic boundary, may be identified with the accuracy necessary for calculating (determining) the thickness t1 and / or thickness t2, and the average height may be identified as needed. Of course, if the thickness t1 and / or t2 are not measured, the interface BS does not need to be observable.

[0074] (3. Capacitor manufacturing method) The manufacturing method for capacitor 1 can be varied. For example, the general procedure may be the same as a known procedure. An example is shown below.

[0075] First, ceramic green sheets are prepared to form the dielectric layer 7 and the insulating layer 17. Next, conductive paste is applied (for example, printed) to the ceramic green sheets to form the internal electrodes 9, dummy electrodes 20, or base electrodes 16. Then, the ceramic green sheets are laminated to form the main body 3. The lamination of the laminate that will form the effective part 11 and the lamination of the part that will form the cover 13 for the laminate may be performed together or separately.

[0076] Up to the point of fabricating the laminate described above, the process is carried out using a base substrate that is large enough to produce multiple main body parts 3. After fabricating the laminate, the base substrate containing the laminate is pieced into pieces (for example, cut) that roughly correspond 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 to form the external electrodes 5.

[0077] Degreasing may be performed before firing. Firing may be carried out, for example, in a reducing atmosphere. Re-oxidation heat treatment may be performed after firing. Polishing (e.g., barrel polishing) of the main body 3 may be performed before and / or after firing. During polishing, for example, the edges of the main body 3 may be chamfered, or the sides of the main body 3 may be polished.

[0078] The external electrode 5 may be formed by various methods. For example, metal may be deposited on the surface of the base electrode 16 and on the edges of the internal electrode 9 by electroless plating and / or electroplating. Alternatively, thin film formation methods such as the dip method, printing method, CVD (Chemical Vapor Deposition), or PVD (Physical Vapor Deposition) may be employed. As can be understood from the above, the base electrode 16 may or may not contribute to the deposition of metal.

[0079] To form the diffusion layer 21, the external electrode 5 and the base electrode 16 are heated while being pressurized. The specific method of this is arbitrary. For example, a heater may be pressed against the external electrode 5, or the condenser 1 may be placed in the furnace together with a device that presses the external electrode 5 against the base electrode 16. Note that the process for forming the diffusion layer 21 may also be combined with other processes (e.g., annealing).

[0080] The heating temperature may be set appropriately according to the specific types of the first and second metals. For example, in the case of Ni and Cu, heating may be carried out so that their temperatures reach 450°C or higher or 600°C or higher. However, this temperature is, for example, below the solidus. The specific magnitude of the pressure is also arbitrary. The thickness of the diffusion layer 21 can be adjusted, for example, by controlling the heating temperature, heating time, and number of heating cycles.

[0081] (4. Capacitor configuration according to other embodiments) (4.1. Second Embodiment, etc.) Figure 4 is a perspective view of the capacitor 201 according to the second embodiment. Figure 3 according to the first embodiment may be referred to as a cross-sectional view of the capacitor 201.

[0082] Generally speaking, capacitor 201 differs from capacitor 1, which is a four-terminal type, in that it is a two-terminal type. In such capacitor 201 as well, a diffusion layer 21 may be configured, as explained with reference to Figure 3.

[0083] The specific shape and dimensions of each part of capacitor 201 may differ from those of capacitor 1, depending on whether it is a two-terminal type. Specifically, they are as follows:

[0084] The shape of the main body 203 (or capacitor 201) is, for example, generally rectangular. This rectangular prism may have a height (length in the D3 direction) equal to or smaller than its width (length in the D2 direction) (as shown in the illustration). The length of the rectangular prism (in the D1 direction) is, for example, greater than its width. The dimensions of the main body 203 are arbitrary. As long as the length in the D1 direction is longer than the length in the D2 direction, specific examples of the dimensions of the main body 3 in the first embodiment may be applied to the dimensions of the main body 203. The external electrodes 5 are generally layered, covering the longitudinal end of the main body 203 across five faces of the rectangular prism.

[0085] The planar shape of the internal electrode 9 is, for example, roughly a rectangle with four sides parallel to the four sides of the rectangular main body 203 (dielectric layer 7). Of the four sides of the internal electrode 9, two long sides and one short side are located inside (not exposed) the side surface of the main body 203, for example. The remaining short side is exposed from the +D1 side or -D1 side of the main body 203. The region of the internal electrode 9 that overlaps with other internal electrodes 9 in a planar view is the electrode body 9a. The portion extending from the electrode body 9a to the external electrode 5 is the lead-out electrode 9b.

[0086] Each dummy layer 19 has, for example, two dummy electrodes 20 at both ends in the longitudinal direction of the main body 203. The planar shape of the dummy electrodes 20 is, for example, rectangular, extending over the entire width (length in the D2 direction) of the main body 203, and is exposed from, for example, the +D1 side or the -D1 side of the main body 203, as well as from the +D2 side and the -D2 side. The above description of the planar configuration of the dummy layer 19 (dummy electrodes 20) may be used in conjunction with the description of the planar configuration of the base layer 15 (base electrode 16).

[0087] Although not specifically illustrated, further examples of capacitor configurations are given.

[0088] The capacitor may have an outer resin covering the entire structure as illustrated in Figure 1 or Figure 4, and lead wires connected to the external electrodes 5 and extending from the outer resin. In another view, the capacitor may be a through-hole mounting type rather than a surface-mount type. In such an embodiment, one external electrode 5 may cover only one side.

[0089] The two types of internal electrodes 9, each connected to a different external electrode 5, may be stacked alternately in pairs rather than one at a time. In this case, for example, the thickness of the dielectric layer 7 between two opposing internal electrodes 9 connected to the same external electrode 5 may be thinner than the thickness of the dielectric layer 7 between two opposing internal electrodes 9 connected to different external electrodes 5. As can be seen from this, the multiple dielectric layers 7 do not have to have the same shape and size.

[0090] Furthermore, the two types of internal electrodes 9 connected to different external electrodes 5 do not necessarily have to face each other. For example, a circuit in which two parallel plate capacitors are connected in series may be formed by providing two types of internal electrodes 9 connected to different external electrodes 5 on the same layer, and providing an internal electrode 9 facing the two types of internal electrodes 9. Alternatively, a circuit in which three or more parallel plate capacitors are connected in series may be formed.

[0091] In the example shown in Figure 4, the portion of the edge of the internal electrode 9 other than, for example, the -D1 side or the +D1 side (referred to in this paragraph as the "non-exposed edge") is not exposed from the side of the main body 203. This non-exposed edge is covered by the portion of the dielectric layer 7 and the insulating layer 17 that extends outward from the non-exposed edge. However, the non-exposed edge may also be covered by layering another dielectric layer on the side of the laminate formed by the dielectric layer 7 and the insulating layer 17, thereby preventing exposure. From another viewpoint, the main body 203 does not need to be a laminated structure in its entirety.

[0092] (4.2. Third Embodiment) Figure 6 is a schematic cross-sectional view showing a part of the capacitor 301 according to the third embodiment, and corresponds to region VI in Figure 3.

[0093] In capacitor 301, diffusion occurs between the internal electrode 9 and the external electrode 5. Diffusion also occurs between the dummy electrode 20 and the external electrode 5. Note that only one of the former or the latter diffusion may occur. Furthermore, the third embodiment may be applied to any of the embodiments described above. The previously stated explanation regarding diffusion between the base electrode 16 and the external electrode 5 (the explanation in Section 2, etc.) may be applied to the diffusion related to the internal electrode 9 and the diffusion related to the dummy electrode 20, for example, by replacing the term "base electrode 16" with the term "internal electrode 9" or "dummy electrode 20," as long as no contradictions arise.

[0094] Specifically, as already mentioned, the lead electrode 9b of the internal electrode 9 (in other words, the edge of the internal electrode 9) and the inner surface of the external electrode 5 are in contact. The internal electrode 9 and the external electrode 5 are fixed together, sharing a diffusion area where their materials are mixed. In a planar perspective view, this diffusion area extends along the edge of the internal electrode 9. In Figure 6, only the internal diffusion area 9c, which is formed by the diffusion of the material of the external electrode 5 into the material of the internal electrode 9, is shown. That is, the external diffusion area, which is formed by the diffusion of the material of the internal electrode 9 into the material of the external electrode 5, is not shown. Note that the contact area between the internal electrode 9 and the external electrode 5 is small. Therefore, the external diffusion area does not actually need to be formed, or it may be so small that it is difficult to observe.

[0095] The above explanation may be applied to the diffusion between the dummy electrode 20 and the external electrode 5, by substituting the term "internal electrode 9" with the term "dummy electrode 20" and the term "internal diffusion section 9c" with the term "dummy diffusion section 20c," provided that no inconsistencies arise.

[0096] The materials of the internal electrode 9, the dummy electrode 20, and the base electrode 16 may be the same as each other or different from each other as described above. This is the same even when diffusion occurs between the internal electrode 9 and the external electrode 5 and / or between the dummy electrode 20 and the external electrode 5. For example, the internal electrode 9, the dummy electrode 20, and the base electrode 16 may be made of Ni or an alloy mainly composed of Ni, and the external electrode 5 may be made of Cu or an alloy mainly composed of Cu.

[0097] The length Li of the internal diffusion part 9c from the edge of the internal electrode 9 (in another aspect, the width of the internal diffusion part 9c extending along the edge of the internal electrode 9 in plan view) is arbitrary. Similarly, the length Ld of the dummy diffusion part 20c from the edge of the dummy electrode 20 (in another aspect, the width of the dummy diffusion part 20c extending along the edge of the dummy electrode 20 in plan view) is arbitrary. For example, at least one of Li < t1, t1 < Ld, and Li < Ld may hold, or all may not hold. For example, Li < t1 < Ld may hold (illustrated example).

[0098] The specific dimensions of Li, Ld, and t1 when the above relative relationship holds are also arbitrary. For example, an example where Li < t1 < Ld (or a part thereof) holds is given. t1 may be 1.05 or more, 1.10 or more, or 1.50 or more of Li, and may be 7.00 or less, 6.00 or less, or 5.00 or less. The above lower and upper limits may be combined arbitrarily with each other. Ld may be 1.05 or more, 1.10 or more, or 1.50 or more of t1, and may be 5.00 or less, 3.00 or less, or 2.00 or less. The above lower and upper limits may be combined arbitrarily with each other. Ld may be 1.10 or more, 1.20 or more, or 1.50 or more of Li, and may be 12.00 or less, 10.00 or less, or 5.00 or less. The above lower and upper limits may be combined arbitrarily with each other. t1 may be 0.30 μm or more and 6.00 μm or less. Li may be 0.20 μm or more and 5.90 μm or less (however, Li < t1). Ld may be 1.00 μm or more and 7.00 μm or less (however, Ld > Li and / or Ld > t1). The difference between Li and t1 may be 0.10 μm or more or 0.30 μm or more. The difference between t1 and Ld may be 0.10 μm or more or 0.30 μm or more. The difference between Li and Ld may be 0.20 μm or more or 0.4 μm or more.

[0099] The above relative relationship and / or conditions such as dimensions may hold only for one external electrode 5, or may hold for two or more (for example, all or more than 50%) of the external electrodes 5. Also, when focusing on each external electrode 5, the above conditions may hold only for one base electrode 16, one internal electrode 9, and / or one dummy electrode 20 joined to the one external electrode 5, or may hold for two or more (for example, all or more than 50%) of each electrode (16, 9, or 20). In the latter case, the actual values of each electrode may satisfy the above conditions, or the average value may satisfy the above conditions.

[0100] For example, when comparing the thickness t1 of one base electrode 16 with the length Li of an internal electrode 9 connected to the same external electrode 5 as the base electrode 16, the average length Li of 10 or more internal electrodes 9 and / or 30% or more (or 60% or more) of the total number of internal electrodes 9 may be used. Similarly, when comparing the thickness t1 (or the average length Li) of one base electrode 16 with the length Ld of a dummy electrode 20 connected to the same external electrode 5 as the base electrode 16, the average length Ld of 2 or more (however, 1 if only one dummy electrode 20 is provided) dummy electrodes 20 and / or 30% or more (or 60% or more) of the total number of dummy electrodes 20 may be compared with the thickness t1 (or the average length Li).

[0101] The above-mentioned conditions relating to the relative relationships and / or dimensions of Li, t1, and Ld do not necessarily have to be met over the entire length of the edges (those in contact with the external electrode 5) of the internal electrode 9 and / or dummy electrode 20. For example, the conditions may be met for 50% or more, or 80% or more, of the length of a specific edge (one or two sides) of the internal electrode 9 (or dummy electrode 20) that is in contact with the external electrode 5. Whether or not the above conditions are met over a certain length can be determined, for example, based on images of a predetermined number of cross-sections (e.g., D1D3 cross-sections) set at equal distances from the edge. If it is difficult to extract images of multiple cross-sections from a single capacitor 1, images of multiple cross-sections can be extracted from multiple capacitors 1 of the same type.

[0102] The length Li may be obtained from a cross-sectional image, such as that shown in Figure 6, obtained by SEM or the like. The cross-section may be, for example, one that follows a direction perpendicular to the edge of the internal electrode 9 in a plan view (for example, the D1 direction), or one that is appropriately separated from the edge (singular portion) of the internal electrode 9 along the above cutting direction (for example, a cross-section that crosses the central position of the edge extending in the D2 direction). Then, similar to the thickness t1, the range in which the main component (second metal) of the external electrode 5 is 12.5 atomic percent or more may be identified as the internal diffusion region 9c, and the length Li may be measured. If there is variation in the length Li in the thickness direction of the internal electrode 9, for example, the maximum value may be used as the length Li for comparison with the thickness t1, etc.

[0103] The above explanation may be applied to length Ld by substituting the terms internal electrode 9, internal diffusion portion 9c, and length Li with the terms dummy electrode 20, dummy diffusion portion 20c, and length Ld, respectively. When determining whether the previously described conditions relating to the relative relationship and / or dimensions of Li, t1, and Ld are satisfied, Li, t1, and Ld may be obtained from the same set of cross-sectional images (or even a single cross-sectional image depending on the circumstances). In this case, a comparison may be made in each cross-section to determine whether the above conditions are satisfied in multiple cross-sections (e.g., 60% or more), or the average values ​​of each dimension (Li, t1, or Ld) in multiple cross-sections may be compared to determine whether the above conditions are satisfied. The thickness t1 measured in each cross-section and compared with Li and / or Ld may be the average value excluding singular parts (e.g., edges). The above average value of thickness t1 may be, for example, the average value over a length of 30% or more, 50% or more, or 80% or more of the total length in the D1 direction of the base electrode 16, taking the D1D3 cross section as an example.

[0104] The manufacturing method for realizing the above conditions regarding the relative relationship and / or dimensions of Li, t1, and Ld is arbitrary. For example, in the manufacturing method described in the first embodiment, the above conditions may be realized by adjusting the particle size of metal particles (e.g., Ni particles) contained in the conductive paste that becomes the base electrode 16, the internal electrode 9, and / or the dummy electrode 20. The larger the particle size of the metal particles contained in each electrode (16, 9, or 20), the easier it is for the material of the external electrode 5 (e.g., Cu) to diffuse into the former electrode. Considering the temperature of each electrode in the heat treatment and the like, by adjusting the particle size, arbitrary Li, t1, and Ld can be realized. For example, in the applicant's prototype, the above conditions were realized by setting the particle size of Ni particles contained in the conductive paste that becomes the internal electrode 9, the base electrode 16, and the dummy electrode 20 to 150 nm to 200 nm, 350 nm to 400 nm, and 350 nm to 400 nm, respectively.

[0105] (5. Example) A prototype of the capacitor 1 according to the embodiment was fabricated, and the adhesion of the external electrode 5 was evaluated. As a result, it was confirmed that a capacitor 1 with a large adhesion of the external electrode 5 can be obtained by the diffusion layer 21. Specifically, it is as follows.

[0106] FIG. 5 is a chart showing the specifications of the capacitor 1 according to the example.

[0107] In this figure, "No." indicates the type of the capacitor according to the example. In Examples E1 to E7, the configurations (thickness t1 and / or thickness t2) related to the diffusion layer 21 are different from each other.

[0108] The columns of "t1 (μm)" and "t2 (μm)" show the values of the thicknesses t1 and t2 in each example. In Examples E1 to E7, each of the thicknesses t1 and t2 is set within the range of 0.9 μm to 3.5 μm. In Examples E1, E6, and E7, t1 = t2. In Examples E2 and E4, t1 < t2. In Examples E3 and E5, t1 > t2.

[0109] The "Qual." column shows the quality evaluation results for capacitor 1 in the examples. Specifically, for each of Examples E1 to E7, 100 samples were prepared and examined for peeling of the external electrode 5 from the underlying electrode 16. In the column above, the number of samples in which peeling occurred is shown as the numerator of the fraction.

[0110] The material of the base electrode 16 was Ni. The material of the external electrode 5 was Cu. The thickness of the base electrode 16 was set to a value within the range of 2 μm to 4 μm (design value: 3 μm). The thickness of the external electrode 5 was set to a value within the range of 2 μm to 10 μm (design value: 6 μm). The thicknesses t1 and t2 were measured based on images obtained by SEM, as described above.

[0111] As shown in Figure 5, in Example E7, where thicknesses t1 and t2 were thinnest, delamination occurred in 2 samples, but in the other Examples E1 to E6, no delamination occurred in 100 samples. Although no samples without the diffusion layer 21 were prepared, the above results suggest that the formation of the diffusion layer 21 reduces the likelihood of the external electrode 5 delaminating.

[0112] In Example E7, where peeling occurred, the thicknesses t1 and t2 were both 0.9 μm. In Examples E1 to E6, where peeling did not occur, the thicknesses t1 and t2 were both 1.0 μm or greater. Therefore, it can be seen that a certain level of adhesion can be obtained by making the thicknesses t1 and t2 each 1.0 μm or greater.

[0113] When the minimum thickness t1 of Examples E1 to E6 (1.0 μm) is normalized by dividing it by an appropriate value selected from the range of thicknesses of the sample's underlying electrode 16 (e.g., 2.0 μm, 3.0 μm, or 4.0 μm), the results are 0.50, 0.33, or 0.25 (rounded to the third decimal place; the same applies hereafter). When the maximum thickness t1 of Examples E1 to E6 (3.5 μm) is normalized by dividing it by an appropriate value selected from the range of thicknesses of the sample's underlying electrode 16 (e.g., 3.5 μm or 4.0 μm), the results are 1.00 or 0.88. The range of thickness t1 may be defined by the lower and / or upper limits obtained in this way. One example of this has already been described.

[0114] When the minimum thickness t2 (1.0 μm) of Examples E1 to E6 is normalized by dividing it by an appropriate value selected from the range of thicknesses of the external electrode 5 of the sample (e.g., 2.0 μm, 6.0 μm, or 10.0 μm), the results are 0.50, 0.17, or 0.10. When the maximum thickness t2 (3.5 μm) of Examples E1 to E6 is normalized by dividing it by an appropriate value selected from the range of thicknesses of the underlying electrode 16 of the sample (e.g., 3.5 μm, 6 μm, or 10 μm), the results are 1.00, 0.58, or 0.35. The range of thickness t2 may be defined by the lower and / or upper limits obtained in this way. One example of this has already been described.

[0115] (6. Summary of Embodiments) In the following description, for convenience, the reference numerals of any of the embodiments will be used. However, the matters described below are also applicable to other embodiments unless they result in inconsistencies. Furthermore, the effects exemplified below do not necessarily have to be achieved.

[0116] The multilayer electronic component (capacitor 1) has an effective portion 11, a cover 13, a base electrode 16, and an external electrode 5. The effective portion 11 has dielectric layers 7 and internal electrodes 9 that are alternately stacked in the stacking direction (D3 direction). The cover 13 on the +D3 side overlaps the effective portion 11 from the +D3 side, of the first side (e.g., +D3 side) and second side (e.g., -D3 side) in the D3 direction. The base electrode 16 on the +D3 side overlaps the cover 13 from the +D3 side. The external electrode 5 on the +D3 side overlaps the base electrode 16 on the +D3 side from the +D3 side. The base electrode 16 and the external electrode 5 may be fixed together by sharing a diffusion layer 21 in which the materials of the base electrode 16 and the materials of the external electrode 5 are mixed with each other.

[0117] Therefore, as described in the overview of the embodiment, for example, the adhesion force of the external electrode 5 to the base electrode 16 can be increased. As a result, the probability of producing defective products in which the external electrode 5 peels off from the base electrode 16 is reduced, and productivity is improved.

[0118] The edge of the internal electrode 9 and the external electrode 5 may be in contact. The thickness t1 of the material of the external electrode 5 that is diffused into the underlying electrode 16 at a concentration of 12.5 atomic percent or more may be greater than the length Li of the portion of the material of the external electrode 5 that is diffused into the internal electrode 9 at a concentration of 12.5 atomic percent or more (internal diffusion portion 9c) from the edge of the internal electrode 9.

[0119] In this case, for example, a relatively thicker thickness t1 improves the effect of increasing the bonding force as described above. On the other hand, a relatively shorter length Li reduces the likelihood of the internal electrode 9 expanding due to diffusion. As a result, for example, the likelihood of delamination between the internal electrode 9 and the dielectric layer 7 is reduced. Furthermore, for example, the likelihood of the capacitor 301's characteristics deteriorating due to expansion (and even delamination) of the internal electrode 9 is reduced.

[0120] The cover 13 may have two or more insulating layers 17 stacked in the D3 direction, and a dummy electrode 20 located at the boundary between the two or more insulating layers 17. The edge of the dummy electrode 20 may be in contact with the external electrode 5. The thickness t1 of the material of the external electrode 5 that is diffused into the base electrode 16 at a concentration of 12.5 atomic percent or more may be smaller than the length Ld from the edge of the dummy electrode 20 of the portion (dummy diffusion portion 20c) where the material of the external electrode 5 is diffused into the dummy electrode 20 at a concentration of 12.5 atomic percent or more.

[0121] In this case, for example, because the length Ld is relatively long, the bonding force between the dummy electrode 20 and the external electrode 5 can be increased. Unlike the internal electrode 9, the dummy electrode 20 does not directly affect the characteristics of the capacitor 1, so when the length Ld is increased, unlike when the length Li is increased, the probability of the characteristics of the capacitor 1 deteriorating is low. Also, the contact area between the dummy electrode 20 and the external electrode 5 is usually smaller than the contact area between the base electrode 16 and the external electrode 5. Therefore, by setting Ld > t1, the overall bonding force of the external electrode 5 to the cover 13 can be easily improved.

[0122] The edge (first edge) of the internal electrode 9 may be in contact with the external electrode 5, and the edge (second edge) of the dummy electrode 20 may be in contact with the external electrode 5. The length Li may be shorter than the length Ld.

[0123] In this case, as can be understood from the explanation above, the bonding force between the dummy electrode 20 and the external electrode 5 can be increased. On the other hand, the probability of expansion (and even detachment) of the internal electrode 9 due to diffusion is reduced.

[0124] The thickness t1 of the material (and / or second metal) of the external electrode 5, which is diffused into the base electrode 16 at a concentration of 12.5 atomic percent or more, may be between 1.0 μm and 3.5 μm. Alternatively, the thickness t1 may be between 0.25 and 0.88 of the thickness of the base electrode 16.

[0125] In this case, for example, by having a thickness t1 of 1.0 μm or more and / or 0.25 or more, the adhesion force of the external electrode 5 to the underlying electrode 16 can be set to a certain level or higher, as described in the examples. If the thickness t1 becomes too large, for example, depending on the types of the first and second metals, the volume of the underlying diffusion layer 16a generally increases. As a result, for example, stress is generated between the underlying diffusion layer 16a and other layers (for example, the insulating layer 17 and / or the underlying non-diffusing layer 16b), causing cracks to form. By having a thickness t1 of 3.5 μm or less and / or 0.88 or less, for example, the probability of such cracks forming can be reduced.

[0126] The thickness t2 of the material (and / or first metal) of the base electrode 16, which is diffused into the external electrode 5 at a concentration of 12.5 atomic percent or more, may be between 1.0 μm and 3.5 μm. Alternatively, the thickness t2 may be between 0.10 and 0.58 of the thickness of the external electrode 5.

[0127] In this case, for example, by having a thickness t2 of 1.0 μm or more and / or 0.10 or more, the adhesion force of the external electrode 5 to the base electrode 16 can be set to a certain level or higher, as described in the examples. When diffusion bonding is performed, voids are formed, depending on the conditions. If the thickness t2 is too large, the proportion of the total volume of voids to the volume of the external electrode 5 becomes high. As a result, for example, the electrical resistivity of the external electrode 5 increases, and the electrical characteristics of the capacitor 1 deteriorate. By having a thickness t2 of 3.5 μm or less and / or 0.58 or less, for example, the deterioration of electrical characteristics as described above can be reduced.

[0128] The thickness t2 may be between 2 / 3 and 3 / 2 of the thickness t1. In other words, the thickness t1 may be between 2 / 3 and 3 / 2 of the thickness t2.

[0129] In this case, for example, the diffusion layer 21 is biased towards one of the substrate electrode 16 and the external electrode 5, and as a result, the probability that the thickness t1 or t2 of the diffusion layer 21 becomes thicker than the total thickness (t1+t2) is reduced. Consequently, the probability of the aforementioned problems occurring due to the thickness t1 or t2 becoming too thick is reduced. From another perspective, the adhesion strength can be increased by increasing the thickness of the diffusion layer 21 while reducing the probability that the thickness t1 or t2 becomes too thick.

[0130] The base electrode 16 may be mainly composed of a first metal in a region at least far from the external electrode 5. The external electrode 5 may be mainly composed of a second metal different from the first metal in a region at least far from the base electrode 16. In the diffusion layer 21, the first metal may be diffused into the external electrode 5, and the second metal may be diffused into the base electrode 16. The diffusion layer 21 has a thickness of 0.01 μm in a cross-section parallel to the D3 direction. 2 The material may contain 12.5 atomic percent or more of the first metal per unit area, and may contain 12.5 atomic percent or more of the first metal.

[0131] In this case, for example, because a certain degree of diffusion occurs, the effects described above are more effectively realized.

[0132] The technology relating to this disclosure is not limited to the embodiments described above and may be implemented in various forms.

[0133] For example, multilayer electronic components are not limited to capacitors. For instance, in a multilayer electronic component, some of the multiple internal electrodes may constitute a capacitor, while the other parts of the multiple internal electrodes may constitute an inductor or resistor. Furthermore, the multilayer electronic component as a whole may constitute an appropriate circuit (e.g., a resonant circuit). In addition, the cover, base electrode, and external electrode may be provided only on either the upper or lower surface of the effective portion.

[0134] The external electrode 5 does not have to be in contact with the internal electrode 9 and / or the dummy electrode 20. For example, the base electrode 16 may cover the end face of the cover 13 and be in contact with the dummy electrode 20, or it may cover the end face of the effective portion 11 and be in contact with the internal electrode 9. [Explanation of Symbols]

[0135] 1...Capacitor, 5...External electrode, 7...Dielectric layer, 9...Internal electrode, 11...Effective part, 13...Cover, 16...Base electrode, 21...Diffusion layer.

Claims

1. An effective portion having dielectric layers and internal electrodes that are alternately stacked in the stacking direction, A cover overlapping the effective portion from the first side, of the first and second sides in the stacking direction, The base electrode overlapping the cover from the first side, It has an external electrode that overlaps the aforementioned base electrode from the first side, The main component of the internal electrode is Ni, The main component of the aforementioned base electrode is Ni, The main component of the external electrode is Cu, The base electrode and the external electrode are fixed together, sharing a diffusion layer in which Ni contained in the base electrode and Cu contained in the external electrode are mixed together. The edge of the internal electrode and the external electrode are in contact. The thickness of the Cu contained in the external electrode that is diffused into the underlying electrode at a concentration of 12.5 atomic percent or more is greater than the length from the edge of the portion of the Cu contained in the external electrode that is diffused into the internal electrode at a concentration of 12.5 atomic percent or more. Stacked electronic components.

2. The aforementioned cover is Two or more insulating layers stacked in the aforementioned stacking direction, It has a dummy electrode located at the boundary of the two or more insulating layers, the main component of which is Ni. The edge of the dummy electrode and the external electrode are in contact. The thickness of the Cu contained in the external electrode that is diffused into the base electrode at a concentration of 12.5 atomic percent or more is smaller than the length from the edge of the portion of the Cu contained in the external electrode that is diffused into the dummy electrode at a concentration of 12.5 atomic percent or more. The stacked electronic component according to claim 1.

3. The aforementioned cover is Two or more insulating layers stacked in the aforementioned stacking direction, It has a dummy electrode located at the boundary of the two or more insulating layers, the main component of which is Ni. The first edge of the internal electrode and the external electrode are in contact. The second edge of the dummy electrode and the external electrode are in contact. The length from the first edge of the portion of the external electrode containing 12.5 atomic percent or more of Cu that is diffused into the internal electrode is shorter than the length from the second edge of the portion of the external electrode containing 12.5 atomic percent or more of Cu that is diffused into the dummy electrode. The stacked electronic component according to claim 1.

4. An effective portion having dielectric layers and internal electrodes that are alternately stacked in the stacking direction, A cover overlapping the effective portion from the first side, of the first and second sides in the stacking direction, The base electrode overlapping the cover from the first side, An external electrode overlapping the aforementioned base electrode from the first side, It has, The base electrode and the external electrode are fixed together, sharing a diffusion layer in which Ni contained in the base electrode and Cu contained in the external electrode are mixed together. The aforementioned cover is Two or more insulating layers stacked in the aforementioned stacking direction, It has a dummy electrode located at the boundary of the two or more insulating layers, the main component of which is Ni. The edge of the dummy electrode and the external electrode are in contact. The thickness of the Cu contained in the external electrode that is diffused into the base electrode at a concentration of 12.5 atomic percent or more is smaller than the length from the edge of the portion of the Cu contained in the external electrode that is diffused into the dummy electrode at a concentration of 12.5 atomic percent or more. Stacked electronic components.

5. An effective portion having dielectric layers and internal electrodes that are alternately stacked in the stacking direction, A cover overlapping the effective portion from the first side, of the first and second sides in the stacking direction, The base electrode overlapping the cover from the first side, An external electrode overlapping the aforementioned base electrode from the first side, It has, The base electrode and the external electrode are fixed together, sharing a diffusion layer in which Ni contained in the base electrode and Cu contained in the external electrode are mixed together. The aforementioned cover is Two or more insulating layers stacked in the aforementioned stacking direction, It has a dummy electrode located at the boundary of the two or more insulating layers, the main component of which is Ni. The first edge of the internal electrode and the external electrode are in contact. The second edge of the dummy electrode and the external electrode are in contact. The length from the first edge of the portion of the external electrode containing 12.5 atomic percent or more of Cu that is diffused into the internal electrode is shorter than the length from the second edge of the portion of the external electrode containing 12.5 atomic percent or more of Cu that is diffused into the dummy electrode. Stacked electronic components.

6. The Cu contained in the external electrode is 12.5 atomic percent or more, and the thickness to which it is diffused in the base electrode is 1.0 μm or more and 3.5 μm or less. Stacked electronic component according to any one of claims 1 to 5

7. The Ni contained in the base electrode is 12.5 atomic percent or more, and the thickness to which it is diffused into the outer electrode is 1.0 μm or more and 3.5 μm or less. A stacked electronic component according to any one of claims 1 to 5.

8. The thickness to which Cu contained in the external electrode is diffused into the base electrode, with a concentration of 12.5 atomic percent or more, is 0.25 to 0.88 of the thickness of the base electrode. A stacked electronic component according to any one of claims 1 to 5.

9. The Ni contained in the base electrode is 12.5 atomic percent or more, and the thickness to which it is diffused into the outer electrode is 0.10 to 0.58 of the thickness of the outer electrode. A stacked electronic component according to any one of claims 1 to 5.

10. The thickness to which Cu contained in the external electrode is diffused into the base electrode at a concentration of 12.5 atomic percent or more is 2 / 3 or more and 3 / 2 or less than the thickness to which Ni contained in the base electrode is diffused into the external electrode at a concentration of 12.5 atomic percent or more. A stacked electronic component according to any one of claims 1 to 5.

11. In the diffusion layer, Ni contained in the base electrode is diffused to the outer electrode and Cu contained in the outer electrode is diffused to the base electrode, The diffusion layer has a cross-section parallel to the stacking direction of 0.01 μm ２ It contains 12.5 atomic percent or more of Ni and 12.5 atomic percent or more of Cu per unit area. A stacked electronic component according to any one of claims 1 to 5.

12. The external electrode is a plated film. A stacked electronic component according to any one of claims 1 to 5.

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