Electronic component

Abstract

The purpose of the present invention is to provide an electronic component having an exceptional anti-migration effect. The present invention provides an electronic component comprising a ceramic element body, and an external electrode continuously covering an end surface of the ceramic element body and some of a side surface adjacent to the end surface, wherein the ceramic element body includes a recessed part having an inner wall and a bottom part opened on the side surface. In a cross-sectional view, the inner wall is connected to the side surface at an edge part of an opening of the recessed part and inclined so that an acute angle is formed with the side surface. The external electrode does not reach the bottom part of the recessed part.

Description

Electronic Components

[0001] The present invention relates to an electronic component, and more particularly to an electronic component including a ceramic body and external electrodes provided on the surface of the ceramic body.

[0002] In electronic components that include a ceramic body and a pair of external electrodes attached to the ceramic body, migration of the metal material forming the external electrodes can occur in a humid environment, resulting in a short circuit between the external electrodes. To prevent or mitigate this migration, various improvements have been made to the structure of the external electrodes and their vicinity.

[0003] For example, Patent Document 1 discloses an electronic component including a ceramic body and external electrodes attached to the ceramic body, in which recesses are formed on the side surfaces of the ceramic body to coincide with the edges of the external electrodes. This recess increases the surface distance between the electrodes, thereby suppressing migration. Patent Document 2 discloses a chip-type ceramic component including a ceramic electronic component body and terminal electrodes covering the end surfaces and side surfaces of the body, in which the terminal electrodes have bonded portions bonded to the end surfaces and side surfaces of the body and non-bonded portions spaced apart from the side surfaces. This ceramic component has been confirmed to have a low failure (short-circuit) rate in a humidity load test.

[0004] International Publication No. WO 2022 / 264969 International Publication No. WO 2017 / 002495

[0005] In order to more reliably reduce malfunctions of electronic components in humid environments, it is desirable to further improve the migration suppression effect obtained by the electronic components disclosed in Patent Documents 1 and 2. Therefore, an object of the present invention is to provide an electronic component with an excellent migration suppression effect.

[0006] According to one aspect of the present invention, there is provided an electronic component comprising a ceramic body and an external electrode continuously covering an end face of the ceramic body and a portion of a side face adjacent to the end face, wherein the ceramic body has a recess that opens into the side face and has an inner wall and a bottom, and in a cross-sectional view, the inner wall connects to the side face at the edge of the opening of the recess and is inclined so that it forms an acute angle with the side face, and the external electrode does not reach the bottom of the recess.

[0007] According to the present invention, it is possible to provide an electronic component that has an excellent migration suppression effect.

[0008] FIG. 1 is a schematic cross-sectional view of a thermistor according to an embodiment. FIG. 2 is an enlarged cross-sectional view of range A in FIG. 1 , showing a preferred embodiment of the recesses in the ceramic body and the external electrodes. FIG. 3A is an enlarged cross-sectional view of range A in FIG. 1 , showing another preferred embodiment of the recesses in the ceramic body and the external electrodes. FIG. 3B is an enlarged cross-sectional view of range A in FIG. 1 , showing yet another preferred embodiment of the recesses in the ceramic body and the external electrodes. FIG. 3C is an enlarged cross-sectional view of range A in FIG. 1 , showing yet another preferred embodiment of the recesses in the ceramic body and the external electrodes. FIG. 3D is an enlarged cross-sectional view of range A in FIG. 1 , showing yet another preferred embodiment of the recesses in the ceramic body and the external electrodes. FIG. 4A is an enlarged cross-sectional view illustrating a method for manufacturing an electronic component according to an embodiment of the present invention. FIG. 4B is an enlarged cross-sectional view illustrating a method for manufacturing an electronic component according to an embodiment of the present invention. FIG. 5 is a schematic cross-sectional view illustrating the configuration of the recesses in the ceramic body and the external electrodes of electronic components according to examples and comparative examples.

[0009] 1 is a schematic cross-sectional view of an electronic component 10 according to an embodiment of the present invention, which shows a so-called multilayer ceramic thermistor. The size of the electronic component 10 is not particularly limited, but can be, for example, 0201 size to 2012 size, and a typical example is 1005 size.

[0010] The electronic component 10 shown in FIG. 1 includes a ceramic body 20 and external electrodes (a pair of external electrodes 31, 32 in FIG. 1 ) provided on the ceramic body 20. One external electrode (first external electrode 31) continuously covers one end face 21 of the ceramic body 20 and a portion of the side face 23 adjacent to the end face 21. The other external electrode (second external electrode 32) continuously covers the other end face 22 of the ceramic body 20 and a portion of the side face 23 adjacent to the end face 22. As shown in FIG. 1 , the electronic component 10 may include a pair of external electrodes 31, 32 provided on both ends of the ceramic body 20, but depending on the type of electronic component, only one of the external electrodes may be provided.

[0011] Each external electrode 31, 32 preferably includes a base layer 31 a, 32 a and a plating layer 31 b, 32 b covering the base layer. The plating layer may have a laminated structure of multiple layers, and in Fig. 1, a two-layer structure is shown, including plating layers 31 b, 32 b (sometimes referred to as "first plating layers") and second plating layers 31 c, 32 c covering the first plating layers 31 b, 32 b. The base layers 31 a, 32 a continuously cover the end faces 21, 22 of the ceramic body 20 and portions of the side faces 23 adjacent to the end faces 21, 22.

[0012] In the following description, the first external electrode 31 and its surrounding structure will be mainly referred to, but the second external electrode 32 and its surrounding structure can also be configured in a similar manner.

[0013] 1 and 2 , electronic component 10 according to this embodiment has a recess 40 on the side surface of ceramic body 20. That is, recess 40 opens to side surface 23 of ceramic body 20. Recess 40 has an inner wall 402 and a bottom 403.

[0014] In a cross-sectional view as shown in FIG. 2 , both the inner wall 402 and the bottom 403 have portions inclined with respect to the side surface 23, but the inclination directions are different. In particular, from the viewpoint of suppressing migration, the inclination direction of the inner wall 402 is important. The inner wall 402 connects to the side surface 23 at the edge 401 a of the opening 401 of the recess 40. The position where the inner wall 402 intersects with the bottom 403 is defined as the intersection position 402 a. In a cross-sectional view, a line connecting the upper edge (edge ​​401 a of the opening 401) and the lower edge (intersection position 402 a) of the inner wall 402 is defined as the reference line L that determines the inclination direction of the inner wall 402. The inner wall 402 is inclined so that the angle θ1 formed between the side surface 23 and the reference line L of the inner wall 402 is an acute angle (less than 90 degrees). In other words, the inner wall 402 is inclined so that the width of the recess 40 increases from the opening 401 toward the bottom 403 (toward the interior of the ceramic body 20) (see FIG. 1 in particular). When such an inner wall 402 is formed, part of the recess 40 extends below the side surface 23 of the ceramic body 20, forming a small space. From another perspective, a portion (protrusion 202a) is formed between the side surface 23 and the inner wall 402, and this protrusion 202a acts as a canopy that covers part of the recess 40.

[0015] The external electrode 31 is formed so as not to reach the bottom 403 of the recess 40. By configuring the external electrode 31 to be spaced apart from the bottom 403 of the recess 40, migration of metal ions from the external electrode 31 can be suppressed. This mechanism will be explained in detail. Arrows (i), (ii), and (iii) in FIG. 2 indicate the direction of migration of metal ions from the external electrode 31 along the surface of the ceramic body 20. Assume that the direction of the electric field generated during use of the electronic component 10 is from left to right in the figure. When each of the arrows (i) to (iii) (vectors) indicating the direction of migration of metal ions is decomposed into a horizontal component and a vertical component, if the horizontal component coincides with the direction of the electric field (from left to right), the migration of metal ions is promoted by the electric field. Conversely, if the horizontal component of the arrow is opposite the direction of the electric field (from right to left), the migration of metal ions is hindered by the electric field.

[0016] In Figure 2, when metal ions move from the external electrode 31 located to the left of the edge 401a of the opening 401 toward the edge 401a, the metal ions travel in the direction of arrow (i) along the side surface 23 of the ceramic body 20 (or along the surface of the external electrode 31). As is clear from Figure 2, the left-right component of the arrow (i) points to the right and coincides with the direction of the electric field. Therefore, it is thought that the metal ions from the external electrode 31 easily reach the edge 401a of the opening 401.

[0017] The metal ions that reach the edge 401a proceed along the inner wall 402 of the recess 40 in the direction of arrow (ii). Here, because the inner wall 402 is inclined so that the angle θ1 between the side surface 23 and the inner wall 402 is an acute angle (less than 90 degrees), the left-right component of the arrow (ii) points leftward, which is opposite to the direction of the electric field. Therefore, the metal ions are prevented from proceeding along the inner wall 402, and it is difficult for them to reach the intersection 402a where the inner wall 402 and the bottom 403 intersect.

[0018] When the metal ions reach the intersection position 402a, they travel in the direction of the arrow (iii) along the bottom 403. The horizontal component of the arrow (iii) points to the right, which coincides with the direction of the electric field. Therefore, the metal ions easily move (migrate) along the bottom 403.

[0019] In this way, by setting the inclination direction of the inner wall 402 of the recess 40 in the opposite direction to the direction of the electric field, it is possible to suppress migration of metal ions from the external electrode 31. Note that if the external electrode 31 reaches the bottom 403 of the recess 40, the external electrode 31 will exceed the intersection position 402a, and the migration suppression effect of the inner wall 402 will not be exerted. Furthermore, there is a risk that metal ions from the external electrode 31 will easily move (migrate) in the direction of the arrow (iii). Therefore, the external electrode 31 needs to be formed so that it does not reach the bottom 403.

[0020] The smaller the angle θ1 between the side surface 23 and the inner wall 402 of the recess 40, the larger the left-right component of the arrow (ii) (the component opposite to the direction of the electric field), and the greater the effect of suppressing migration. Therefore, the angle θ1 is preferably 70 degrees or less, more preferably 60 degrees or less, and particularly preferably 50 degrees or less. On the other hand, if the angle θ1 is too small, the strength of the protrusion 202a sandwiched between the side surface 23 and the inner wall 402 decreases, so the angle θ1 is preferably 5 degrees or more.

[0021] The external electrode 31 can take various forms as shown in Figures 3A to 3D. In the example shown in Figure 3A, the external electrode 31 (composed of an underlayer 31a and a plating layer 31b) covering the side surface 23 extends to the edge 401a of the opening 401 of the recess 40. The underlayer 31a extends to the vicinity of the edge 401a (but does not reach the edge 401a), and the plating layer 31b covers the entire underlayer 31a and reaches the edge 401a.

[0022] 3B, similarly to Fig. 3A, the external electrode 31 covering the side surface 23 extends to the edge 401a of the opening 401 of the recess 40. Note that the base layer 31a extends to the edge 401a, and a portion of the base layer 31a (more specifically, the portion of the base layer 31a covering the side surface 23 near the edge 401a) is not covered with the plating layer 31b and is therefore exposed from the plating layer 31b.

[0023] 3C , the external electrode 31 (comprised of the base layer 31a and the plating layer 31b) covering the side surface 23 extends beyond the edge 401a of the opening 401 of the recess 40 to the inner wall 402, and a portion of the inner wall 402 is covered by the external electrode 31. The base layer 31a extends to the edge 401a, and the plating layer 31b covers the entire base layer 31a and also partially covers the inner wall 402 of the recess 40.

[0024] 3D , the external electrode 31 covering the side surface 23 is peeled off from the side surface 23 near the edge 401 a of the opening 401 of the recess 40. In other words, in the present invention, the external electrode 31 does not need to extend to the edge 401 a of the opening 401.

[0025] Referring again to FIG. 2 , the ceramic body 20 is preferably made of porous ceramic. Using porous ceramic allows the glass component contained in the base layer 31a to be impregnated near the surface of the side surface 23. The portion of the ceramic body 20 containing the glass component is referred to as the “surface layer 202,” and the portion of the ceramic body 20 not containing the glass component is referred to as the “porous ceramic layer 201.” Because the surface layer 202 is less susceptible to etching than the porous ceramic layer 201, the porous ceramic layer 201 can be preferentially etched to form the recess 40 having the shape shown in FIG. 2 . From the viewpoint of facilitating the formation of the recess 40 having the shape shown in FIG. 2 , the ceramic body 20 preferably includes the surface layer 202 containing the glass component. The surface layer 202 can be formed mainly in the region of the surface of the ceramic body 20 that is covered by the base layer 31a (and the surrounding region). Since the surface layer 202 is formed by impregnation with the glass component contained in the base layer 31a, the surface layer 202 may contain an element identical to at least one of the elements contained in the base layer 31a (particularly, the element contained in the glass component).

[0026] It can be confirmed from element mapping in cross-sectional SEM-EDX measurement that the surface layer 202 contains the same elements (glass components) as those contained in the base layer 31a. If the element to be identified is not contained in the ceramic body 20, the area of ​​the ceramic body 20 that contains the element is the surface layer 202. If the element to be identified is contained in the ceramic body 20, the area of ​​the ceramic body 20 that contains the element in relatively high amounts is the surface layer 202, and the area of ​​the ceramic body 20 excluding the surface layer 202 that contains the element in relatively low amounts is the ceramic body 20.

[0027] In the surface layer 202, the glass component can penetrate into the pores of the porous ceramic, so the number of pores is reduced compared to the original porous ceramic. In other words, the porosity of the surface layer 202 is lower than the porosity of the ceramic body 20 (porous ceramic layer 201) other than the surface layer 202. The fact that the porosity of the surface layer 202 is lower than the porosity of the ceramic body 20 other than the surface layer 202 can be easily confirmed by visually observing a cross-sectional SEM image.

[0028] As will be described later, the recess 40 can be formed by taking advantage of the fact that the surface layer 202 is resistant to etching. In other words, when the ceramic body 20 is etched after the surface layer 202 is formed, the surface layer 202 remains, and etching of the ceramic body 20 (porous ceramic) below the surface layer 202 progresses. As a result, the unetched surface layer 202 forms the inner wall 402, and the ceramic body 20 (porous ceramic layer 201) other than the surface layer 202 forms the bottom 403, thereby forming the recess 40. In other words, within the recess 40, the surface layer 202 is exposed only at the inner wall 402, and the ceramic body 20 (porous ceramic layer 201) other than the surface layer 202 is exposed from the bottom 403.

[0029] The base layer 31a preferably contains, as a metal element, one or more selected from the group consisting of Ag, AgPd, and Cu, and, as a glass component, preferably contains, as an oxide of one or more selected from the group consisting of Si, Al, B, Ba, Zn, Ti, and Zr.

[0030] The thickness of the surface layer 202 is, for example, 1 μm or more and 20 μm or less. Because the thickness of the surface layer 202 is related to the length of the inner wall 402, by making the thickness of the surface layer 202 1 μm or more, the inner wall 402 can be formed with a sufficient distance, further improving the migration suppression effect. Furthermore, because the thickness of the surface layer 202 is related to the depth of the recess 40 (the amount of removal of the ceramic body 20), by making the thickness of the surface layer 202 20 μm or less, the amount of the ceramic body 20 removed by etching can be reduced. Because the volume of the ceramic body 20 affects the characteristics of electronic components, reducing the amount of removal of the ceramic body 20 can reduce deterioration of the characteristics of electronic components.

[0031] The thickness of the surface layer 202 is determined from the cross-sectional SEM-EDX image. The surface layer 202 is determined from the cross-sectional SEM-EDX image using the method described above, and the thickest part is defined as the "thickness (maximum thickness) of the surface layer 202."

[0032] Examples of electronic components 10 suitable for application of the present invention include chip-type ceramic electronic components such as thermistors, including positive temperature coefficient (PTC) thermistors and negative temperature coefficient (NTC) thermistors, varistors, and capacitors. Note that for these electronic components, the material and configuration of the ceramic layer 20c can be selected depending on the desired characteristics.

[0033] 1, the ceramic body 20 may have a layered structure including ceramic layers (e.g., semiconductor ceramic layers) 20c and internal electrodes 20e. The ceramic material (e.g., ceramic semiconductor material) for forming the ceramic layers 20c is selected according to the type of desired electronic component 10.

[0034] For example, in the case of an NTC thermistor having a negative resistance-temperature characteristic, the ceramic semiconductor material contains a P-type semiconductor having a negative resistance-temperature characteristic as a main component, such as a ceramic containing manganese oxide as a main component, and may contain one or more of nickel oxide, cobalt oxide, alumina, iron oxide, titanium oxide, zirconium oxide, copper oxide, zinc oxide, etc.

[0035] In the case of a multilayer capacitor, the ceramic material is, for example, BaTiO ３ , CaTiO ３ , SrTiO ３ , CaZrO ３ , (BaSr)TiO ３ , Ba(ZrTi)O ３ and (BiZn)Nb ２ O ７ The dielectric materials used are as follows.

[0036] The material for forming the internal electrode 20e is not particularly limited as long as it is conductive, and examples thereof include materials containing one or more of Ag, Cu, Pt, Ni, Al, Pd, Au, etc., and materials containing one or more of Ag, Cu, and Ni are particularly preferred.

[0037] As will be described later, in the electronic component 10 according to this embodiment, the recesses 40 can be formed mainly by two methods: etching with acid (chemical processing) and cutting (mechanical processing) such as laser processing. Chemical processing is preferable because it allows the recesses to be formed in accordance with the positions of the external electrodes 31 and allows multiple electronic components 10 to be processed simultaneously. However, chemical processing has the limitation that the material constituting the ceramic layer must be soluble in the etching solution. An example of an electronic component having a ceramic layer (semiconductor ceramic layer) 20c that can be chemically processed is a thermistor.

[0038] An example of an electronic component to which chemical processing cannot be applied is a varistor. In the case of a varistor, mechanical processing is performed instead of chemical processing. Mechanical processing is preferable in that it does not require consideration of solubility in acid (etchant), and therefore recesses 40 can be formed in any electronic component.

[0039] [Method for Manufacturing Electronic Component 10] A method for manufacturing electronic component 10 according to this embodiment will be described below using a thermistor having the structure shown in Fig. 1 as an example. A method for forming recess 40 will be described with reference to Figs. 4A and 4B.

[0040] (Fabrication of Ceramic Body 20) The ceramic body 20 is preferably formed from porous ceramic. Porous ceramic can be manufactured by known techniques such as adjusting the amount of binder to be mixed and controlling the firing temperature and firing time.

[0041] First, for example, Mn ３ O ４ Powder, Co ３ O ４ Starting materials such as NiO powder and NiO powder are weighed to obtain a predetermined composition and wet-mixed in a ball mill. The mixed materials are then calcined at, for example, 900°C. The calcined materials are then pulverized again in a ball mill, and a dispersant and an organic binder are added and mixed to obtain a slurry.

[0042] The resulting slurry is then molded using a doctor blade method or the like to produce ceramic green sheets. Next, a conductive paste for internal electrodes (e.g., a conductive paste mainly composed of Ag—Pd) is applied to the surfaces of the ceramic green sheets to form internal electrode patterns. The internal electrode paste may be applied, for example, by screen printing or the like. A predetermined number of ceramic green sheets with internal electrode patterns formed in this manner are stacked, and then sandwiched and pressure-bonded between ceramic green sheets without internal electrode patterns to produce a laminate. This laminate is then cut to a predetermined size, subjected to a binder removal process, and then fired in air at a predetermined temperature (1200 to 1400°C) to obtain a ceramic element body 20 (ceramic laminate) having a laminated structure consisting of ceramic layers 20c and internal electrodes 20e.

[0043] (Formation of Base Layers 31a, 32a) As shown in FIG. 1 , the base layers 31a, 32a are formed to cover the end faces 21, 22 and a portion of the side face 23 of the ceramic body 20. The base layers 31a, 32a are formed by various thin film formation methods, various printing methods, dipping methods, or the like. For example, when forming the base layers 31a, 32a by dipping, a conductive paste is applied to both end faces of the ceramic body and then baked. The conductive paste contains an organic solvent, metal particles, and a glass component. The metal particles contained in the conductive paste preferably contain one or more metals selected from the group consisting of Ag, AgPd, and Cu. The glass component contained in the conductive paste preferably contains one or more oxides selected from the group consisting of Si, Al, B, Ba, Zn, Ti, and Zr.

[0044] The baking temperature of the conductive paste is, for example, 840°C. During this baking process, some of the glass components contained in the conductive paste penetrate into the ceramic body 20 made of porous ceramic, forming a surface layer 202 (see FIG. 4A). The portion of the ceramic body 20 other than the surface layer 202 is referred to as a "porous region 201'." Note that while FIG. 4A illustrates a plating layer 31b covering the base layer 31a, the plating layer 31b is not formed when the conductive paste is baked. The thickness of the surface layer 202 can be adjusted by the baking conditions of the conductive paste (baking temperature and baking time), the porosity of the ceramic body 20 (porous ceramic), and the like.

[0045] (Formation of recess 40) The side surface 23 of the ceramic body 20 is etched to form the recess 40 (see FIGS. 1 and 2). When the ceramic body 20 is acid-etched, the porous region 201' is eroded by the etching, while the surface layer 202 remains largely unetched. Therefore, after the acid etching, the surface layer 202 remains, forming the protruding portion 202a, and the porous region 201' below the surface layer 202 (protruding portion 202a) is etched, forming the recess 40 (see FIG. 4B). The porous region 201' remaining after etching becomes the porous ceramic layer 201.

[0046] (Formation of plating layers 31b, 32b, second plating layers 31c, 32c) The plating layers 31b, 32b (see FIG. 1) are formed to cover the surfaces of the base layers 31a, 32a. The plating layers 31b, 32b can be formed by electrolytic plating of one or more metal materials selected from, for example, Ni, Sn, Pd, and Au.

[0047] The morphology of the plating layers 31b, 32b can be controlled by changing the time for forming the plating layers 31b, 32b. Shortening the plating time results in a morphology in which the plating layer 31b partially covers the base layer 31a, as shown in Fig. 3B. Longer plating time results in a morphology in which the plating layer 31b completely covers the base layer 31a, as shown in Fig. 3A. Further increasing the plating time results in a morphology in which the plating layer 31b extends to the inner wall 402 of the recess 40, as shown in Fig. 3C.

[0048] 1, the plating layer may have a two-layer structure. In this case, after plating layers (first plating layers) 31b, 32b are formed, second plating layers 31c, 32c are formed to cover the first plating layers 31b, 32b. When forming a plating layer with a two-layer structure, the first plating layers 31b, 32b are preferably formed by electrolytic plating of at least one of Ni and Cu, for example, and the second plating layers 31c, 32c are preferably formed by electrolytic plating of Sn, for example.

[0049] The plating layers (first plating layers) 31b, 32b and the second plating layers 31c, 32c can be formed by a known plating method, for example, barrel plating using balls.

[0050] In the above-described method, after forming the base layers 31a and 32a, the recesses 40 are formed by etching, and then the plating layers 31b and 32b are formed, but the plating layers 31b and 32b may be formed before forming the recesses 40. For example, as shown in Fig. 3A, a configuration in which the plating layer 31b extends to the edge 401a of the opening 401 can be easily formed by forming the plating layers 31b and 32b and then etching to form the recesses 40.

[0051] [Electronic Component Manufacturing Method (Modified Example)] The modified example differs from the above-described manufacturing method using chemical processing (etching) in that the recess 40 is formed by mechanical processing. First, as in the manufacturing method according to the present embodiment, the ceramic body 20 is formed. Then, the recess 40 is formed on the side surface 23 of the ceramic body 20 by mechanical processing such as laser processing. Then, as in the manufacturing method according to the present embodiment, the base layers 31 a, 32 a and the plating layers 31 b, 32 b (and the second plating layers 31 c, 32 c) are formed in sequence. This modified example makes it possible to manufacture an electronic component 10 having the recess 40 even when the ceramic layer 20 c included in the ceramic body 20 is formed of a material that is insoluble in a plating solution.

[0052] The method for manufacturing an electronic component according to an embodiment of the present invention and its modified examples have been described above using an NTC thermistor having internal electrodes as an example. However, other electronic components such as NTC thermistors, PTC thermistors, varistors, and capacitors that do not have internal electrodes can also be manufactured as appropriate based on the description in this specification.

[0053] An electronic component (thermistor) having the structure shown in Figure 1 was produced using the manufacturing method for electronic component 10 according to the embodiment. The material and dimensions of the thermistor were as follows: Electronic component: Multilayer ceramic type thermistor Electronic component size: 1005 size, prismatic type Ceramic layer material: Porous ceramics mainly composed of manganese oxide, containing nickel oxide and cobalt oxide Base layer material: Cu Plating film material: First plating layer Ni, second plating layer Sn Number of plating film layers: 2

[0054] Electronic components (Example and Comparative Example) having a recess with a cross-sectional shape as shown in FIG. 5 were fabricated. In the electronic component 10 of the Example, the angle θ1 between the side surface and the inner wall of the recess was an acute angle (approximately 30 degrees), while in the electronic component 100 of the Comparative Example, the angle θ1 was an obtuse angle (approximately 150 degrees). The resulting electronic components 10 and 100 were mounted on a mounting board, and then energized in a humid environment to confirm whether migration occurred. The test conditions were controlled so that the electronic components were cycled between a high-humidity environment and a dry environment to a degree that prevented thermal runaway. After the test, the side surface 23 of the ceramic body 20 was observed with a stereomicroscope to confirm whether migration had occurred. If migration had occurred, a metallic luster was observed on the side surface 23. It is also possible to confirm whether migration had occurred on the side surface 23 by performing surface SEM-EDX measurement of the side surface 23 and observing elemental mapping of the metal element (Ag).

[0055] In electronic component 10 of the example, no migration was observed on side surface 23 of ceramic body 20. On the other hand, in electronic component 100 of the comparative example, traces of migration (metallic luster) were observed on side surface 23.

[0056] The disclosure of this specification may include the following aspects: <1> An electronic component including a ceramic body and an external electrode continuously covering an end face of the ceramic body and a part of a side face adjacent to the end face, wherein the ceramic body has a recess that opens to the side face and has an inner wall and a bottom, wherein, in a cross-sectional view, the inner wall connects to the side face at an edge of the opening of the recess and is inclined so as to form an acute angle with the side face, and the external electrode does not reach the bottom of the recess.

[0057] <2> The electronic component according to <1>, wherein the external electrode further extends from the part of the side surface to cover the edge of the opening of the recess.

[0058] <3> The electronic component according to <1> or <2>, wherein the external electrode further continuously covers the part of the side surface, beyond the edge of the opening of the recess, and onto a part of the inner wall.

[0059] <4> The electronic component according to <1>, wherein the external electrodes are peeled off from the side surfaces near the edges of the openings of the recesses.

[0060] <5> The electronic component according to any one of <1> to <4>, wherein the external electrodes include an underlayer in contact with the ceramic body and a plating layer covering the underlayer.

[0061] <6> The electronic component according to <5>, wherein the underlayer continuously covers an area from the end face of the ceramic body to the edge of the opening of the recess, and a portion covering the vicinity of the edge is exposed from the plating layer.

[0062] <7> The electronic component according to <5>, wherein the base layer continuously covers from the end face of the ceramic body to the edge of the opening of the recess, and the plating layer continuously covers the base layer and a portion of the inner wall of the recess.

[0063] <8> The electronic component according to any one of <5> to <7>, wherein the ceramic body is made of porous ceramic, the surface of the ceramic body has a surface layer in a region covered with the base layer, the surface layer containing at least one element identical to the element contained in the base layer, and the surface layer is exposed only from the inner wall within the recess.

[0064] <9> The electronic component according to <8>, wherein the element contained in the underlayer is at least one element selected from the group consisting of Si, Al, B, Ba, Zn, Ti, and Zr.

[0065] <10> The electronic component according to <8> or <9>, wherein the porosity of the surface layer is lower than the porosity of the ceramic body other than the surface layer.

[0066] <11> The electronic component according to any one of <8> to <10>, wherein the surface layer has a thickness of 1 μm or more and 20 μm or less.

[0067] <12> The electronic component according to any one of <1> to <11>, wherein the ceramic body has a laminated structure made up of semiconductor ceramic layers and internal electrodes.

[0068] <13> The electronic component according to any one of <1> to <12>, which is a thermistor.

[0069] This application claims priority based on Japanese Patent Application No. 2024-071839, filed on April 25, 2024, the entire contents of which are incorporated herein by reference.

[0070] REFERENCE SIGNS LIST 10 Electronic component 20 Ceramic body 21, 22 End faces of ceramic body 23 Side face of ceramic body 201 Porous ceramic layer 201' Porous region 202 Surface layer 31, 32 External electrodes 31a, 32a Underlayer 31b, 32b Plating layer (first plating layer) 31c, 32c Second plating layer 40 Recess 401 Opening of recess 401a Edge of opening 402 Inner wall 403 Bottom

Claims

1. An electronic component comprising a ceramic body and an external electrode continuously covering an end face of the ceramic body and a portion of a side face adjacent to the end face, wherein the ceramic body has a recess that opens to the side face and has an inner wall and a bottom, and in a cross-sectional view, the inner wall connects to the side face at the edge of the opening of the recess and is inclined so that it forms an acute angle with the side face, and the external electrode does not reach the bottom of the recess.

2. The electronic component according to claim 1, wherein said external electrodes further extend to cover said portions of said side surfaces as well as said edges of said openings of said recesses.

3. The electronic component according to claim 1 or 2, wherein the external electrode further covers continuously from the part of the side surface, beyond the edge of the opening of the recess, to a part of the inner wall.

4. The electronic component according to claim 1, wherein the external electrodes are peeled off from the side surfaces near the edges of the openings of the recesses.

5. The electronic component according to any one of claims 1 to 4, wherein the external electrodes include an underlayer in contact with the ceramic body, and a plating layer covering the underlayer.

6. The electronic component according to claim 5, wherein the base layer continuously covers from the end face of the ceramic body to the edge of the opening of the recess, and the portion covering the vicinity of the edge is exposed from the plating layer.

7. The electronic component according to claim 5, wherein the base layer continuously covers from the end face of the ceramic body to the edge of the opening of the recess, and the plating layer continuously covers the base layer and a portion of the inner wall of the recess.

8. An electronic component according to any one of claims 5 to 7, wherein the ceramic body is made of porous ceramic, the surface of the ceramic body has a surface layer in the area covered with the base layer, the surface layer containing at least one element identical to the elements contained in the base layer, and the surface layer is exposed only from the inner wall within the recess.

9. The electronic component according to claim 8, wherein the element contained in the underlayer is one or more elements selected from the group consisting of Si, Al, B, Ba, Zn, Ti, and Zr.

10. The electronic component according to claim 8 or 9, wherein the porosity of the surface layer is lower than the porosity of the ceramic body other than the surface layer.

11. The electronic component according to any one of claims 8 to 10, wherein the surface layer has a thickness of 1 μm or more and 20 μm or less.

12. The electronic component according to any one of claims 1 to 11, wherein the ceramic body has a laminated structure made up of semiconductor ceramic layers and internal electrodes.

13. The electronic component according to any one of claims 1 to 12, which is a thermistor.

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