Coil component

Abstract

To provide a coil component that can improve the bonding strength between the external electrode and solder.SOLUTION: A coil component 1 includes an element body 2 containing soft magnetic metal particles P, a coil 5 disposed within the element body 2, and external electrodes 3 and 4 connected to the coil 5. The external electrodes 3 and 4 have a base metal layer 8 provided on the outer surface 2s of the element body 2, and a plating layer 9 covering the base metal layer 8. The plating layer 9 is provided on an outer edge 9a of the plating layer 9 and has protrusions 9b that extend into the element body 2.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a coil component. [Background technology]

[0002] A coil component is known that includes an element body, a coil disposed within the element body, and external electrodes connected to the coil (see, for example, Patent Document 1). Patent Document 1 describes that the external electrodes of the passive component are soldered to land patterns, thereby mounting the passive component on a circuit board. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-141079 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present disclosure is to provide a coil component that can improve the bonding strength between external electrodes and solder. [Means for solving the problem]

[0005] (1) A coil component according to one aspect of the present disclosure comprises a base body containing soft magnetic metal particles, a coil disposed within the base body, and an external electrode connected to the coil, wherein the external electrode has a base metal layer provided on an outer surface of the base body and a plating layer covering the base metal layer, and the plating layer has a protrusion provided on the outer edge of the plating layer and extending into the base body.

[0006] In the coil component described above, the plating layer has protrusions that penetrate into the body, which increases the surface area of ​​the plating layer that bonds with the solder compared to a configuration in which the plating layer does not have protrusions, thereby improving the bonding strength between the external electrodes and the solder.

[0007] (2) In the coil component of (1) above, the outer surface may have a mounting surface, and the external electrodes may be provided only on the mounting surface. In this case, improving the bonding strength between the external electrodes and the solder is more important than in a configuration in which the external electrodes are provided across multiple surfaces. Therefore, a configuration in which the plating layer has protrusions is particularly effective.

[0008] (3) In the coil component of (1) or (2), the base metal layer may have an embedded portion embedded in the element body. In this case, the external electrodes are less likely to peel off from the element body. This improves the mounting strength when the coil component is mounted on a circuit board by soldering.

[0009] (4) In the coil component of (3) above, the outer surface may have a peripheral portion of the external electrode, and the embedded portion may have an exposed surface exposed from the outer surface and a side surface adjacent to the exposed surface, and the angle formed between the peripheral portion and the side surface may be 90 degrees or less. In this case, the gap between the soft magnetic metal particle and the side surface of the embedded portion tends to be large. By forming protrusions of the plating layer in the large gap, the surface area of ​​the plating layer that bonds with the solder is further increased. This can further improve the bonding strength between the external electrode and the solder.

[0010] (5) In any one of the coil components (1) to (4) above, the base metal layer may not contain a glass component. In this case, the area of ​​the base metal material on the surface of the base metal layer is larger than when the base metal layer contains a glass component. This makes it easier to form a plating.

[0011] (6) In the coil component of any one of (1) to (5) above, the protrusions may be provided along the entire periphery of the plating layer. In this case, the surface area of ​​the plating layer increases along the entire periphery of the plating layer, thereby further improving the bonding strength between the external electrode and the solder.

[0012] (7) In any one of the coil components (1) to (6) above, the outer surface may have a mounting surface and a pair of end surfaces adjacent to the mounting surface and facing each other, the pair of external electrodes may be provided on the mounting surface spaced apart from each other in the opposing direction of the pair of end surfaces, the mounting surface may have a central region disposed between the pair of external electrodes when viewed from a direction perpendicular to the mounting surface, and the protrusions may be provided on an outer edge of the plating layer adjacent to the central region. In this case, when the coil component is mounted on a circuit board, stress is likely to be applied between the central region and the external electrodes. By providing the protrusions along the central region, it is possible to improve the bonding strength between the external electrodes and the solder in the area where stress is likely to be applied when the coil component is mounted.

[0013] (8) In the coil component of any one of (1) to (7), the element body may have a first region provided in contact with the external electrode and a second region provided in contact with the coil, and the average particle size of the soft magnetic metal particles contained in the first region may be larger than the average particle size of the soft magnetic metal particles contained in the second region. In this case, it is easy to form protrusions while maintaining the characteristics of the coil.

[0014] (9) In the coil component according to any one of (1) to (8), the average depth to which the protrusions penetrate into the element body may be equal to or greater than half the average particle diameter of the soft magnetic metal particles, thereby reliably improving the bonding strength between the external electrodes and the solder. [Effects of the Invention]

[0015] According to the present disclosure, a coil component is provided that can improve the bonding strength between the external electrodes and the solder. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a perspective view of a coil component according to a first embodiment. [Figure 2] FIG. 2 is a see-through perspective view of the coil component shown in FIG. [Figure 3]FIG. 3 is an exploded perspective view of the coil component shown in FIG. [Figure 4] FIG. 4 is a view of the coil component shown in FIG. 1 as seen from the mounting surface side. [Figure 5] FIG. 5 is a cross-sectional view of the coil device shown in FIG. [Figure 6] FIG. 6 is a perspective view of a coil component according to the second embodiment. [Figure 7] FIG. 7 is a cross-sectional view of the coil device shown in FIG. [Figure 8] FIG. 8 is an exploded perspective view of the coil component shown in FIG. [Figure 9] FIG. 9 is a cross-sectional view of a coil component according to a first modified example of the first embodiment. [Figure 10] FIG. 10 is a cross-sectional view of a coil component according to a second modified example of the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or corresponding elements are designated by the same reference numerals, and redundant description will be omitted.

[0018] (First embodiment) A coil component 1 according to a first embodiment will be described with reference to Figures 1 to 5. As shown in Figures 1 to 5, the coil component 1 includes an element body 2, external electrodes 3 and 4, a coil 5, a first connecting conductor 6, and a second connecting conductor 7. The coil component 1 is a laminated coil component. For ease of explanation, the element body 2 is indicated by a dashed line in Figure 2.

[0019] The element body 2 has a rectangular parallelepiped shape. The rectangular parallelepiped shape includes a rectangular parallelepiped shape with chamfered corners and ridges, and a rectangular parallelepiped shape with rounded corners and ridges. The outer surface 2s of the element body 2 has a pair of end faces 2a and 2b, a pair of main faces 2c and 2d, and a pair of side faces 2e and 2f. The end faces 2a and 2b face each other. The main faces 2c and 2d face each other. The side faces 2e and 2f face each other. In this embodiment, the opposing direction of the main faces 2c and 2d is defined as a first direction D1, the opposing direction of the end faces 2a and 2b is defined as a second direction D2, and the opposing direction of the side faces 2e and 2f is defined as a third direction D3. The first direction D1, the second direction D2, and the third direction D3 are substantially perpendicular to each other.

[0020] The end faces 2a, 2b extend in the first direction D1 to connect the principal faces 2c, 2d. The end faces 2a, 2b also extend in the third direction D3 to connect the side faces 2e, 2f. The principal faces 2c, 2d extend in the second direction D2 to connect the end faces 2a, 2b. The principal faces 2c, 2d also extend in the third direction D3 to connect the side faces 2e, 2f. The side faces 2e, 2f extend in the first direction D1 to connect the principal faces 2c, 2d. The side faces 2e, 2f also extend in the second direction D2 to connect the end faces 2a, 2b.

[0021] The main surface 2d is a mounting surface, and is the surface that faces another electronic device (not shown) when the coil component 1 is mounted on the other electronic device (for example, a circuit board or a laminated coil component). The end surfaces 2a and 2b are surfaces that are continuous with the mounting surface (i.e., the main surface 2d). The end surfaces 2a and 2b are also surfaces that are adjacent to the mounting surface.

[0022] The length of the element body 2 in the second direction D2 is longer than the length of the element body 2 in the first direction D1 and the length of the element body 2 in the third direction D3. The length of the element body 2 in the third direction D3 is longer than the length of the element body 2 in the first direction D1. That is, in this embodiment, the end faces 2a, 2b, main faces 2c, 2d, and side faces 2e, 2f have a rectangular shape. The length of the element body 2 in the first direction D1 may be equal to or shorter than the length of the element body 2 in the third direction D3.

[0023] In the description of the embodiments, "equivalent" may mean not only equal but also values ​​that include slight differences or manufacturing errors within a preset range. For example, if multiple values ​​are within a range of ±5% of the average value of the multiple values, the multiple values ​​are defined as equivalent.

[0024] The element body 2 is formed by stacking a plurality of element layers (magnetic layers) 10a-10h in a first direction D1. That is, the stacking direction of the element body 2 is the first direction D1. The specific stacking configuration will be described later. In the actual element body 2, the plurality of element layers 10a-10h are integrated to the extent that the boundaries between the layers are not visible.

[0025] The element body 2 includes a plurality of soft magnetic metal particles P (see FIG. 5). The soft magnetic metal particles P are made of a soft magnetic alloy (soft magnetic material). The soft magnetic alloy is, for example, an Fe-Si alloy. When the soft magnetic alloy is an Fe-Si alloy, it may also include P. The soft magnetic alloy may also be, for example, an Fe-Ni-Si-M alloy. "M" includes one or more elements selected from Co, Cr, Mn, P, Ti, Zr, Hf, Nb, Ta, Mo, Mg, Ca, Sr, Ba, Zn, B, Al, and rare earth elements.

[0026] In the element body 2, the soft magnetic metal particles P, P are bonded to each other. The bond between the soft magnetic metal particles P, P is realized, for example, by bonding between oxide films (not shown) formed on the surfaces of the soft magnetic metal particles P. The thickness of the oxide film is, for example, 5 nm to 60 nm. The oxide film may be composed of one or more layers. Resin is present in at least some of the gaps between the soft magnetic metal particles P, P. The resin has electrical insulating properties and may be, for example, silicone resin, phenol resin, acrylic resin, or epoxy resin.

[0027] As shown in FIG. 5, the element body 2 has a first region R1 provided in contact with the external electrodes 3, 4, and a second region R2 provided in contact with the coil 5. In this embodiment, the first region R1 includes the entire main surface 2d and is a region that is thicker than the embedded portion 8b in the first direction D1. The second region R2 is all of the region of the element body 2 other than the first region R1. The size (volume) of the gaps between the soft magnetic metal particles P, P in the first region R1 is larger than the size (volume) of the gaps between the soft magnetic metal particles P, P in the second region R2. For example, the first region R1 includes an element body layer 10h (see FIG. 3) and one element body layer 10g (see FIG. 3) adjacent to the element body layer 10h. The second region R2 includes the remaining element body layers.

[0028] The external electrodes 3 and 4 are provided on the element body 2 and connected to the coil 5. The external electrodes 3 and 4 are so-called bottom electrodes and are provided only on the mounting surface (principal surface 2d). The external electrodes 3 and 4 have the same shape. The external electrodes 3 and 4 are provided on the mounting surface (principal surface 2d) spaced apart from each other in the second direction D2. Specifically, the external electrode 3 is arranged on the end surface 2a side of the element body 2. The external electrode 4 is arranged on the end surface 2b side of the element body 2.

[0029] The coil 5 is disposed within the element body 2. As shown in FIG. 3, the coil 5 is composed of a plurality of coil conductor layers 12a to 12e. The plurality of coil conductor layers 12a to 12e are electrically connected to each other to form the coil 5 within the element body 2. The coil axis of the coil 5 is provided along the first direction D1. The coil conductor layers 12a to 12e are disposed so as to at least partially overlap each other when viewed from the first direction D1. The plurality of coil conductor layers 12a to 12e are made of a conductive material (for example, Ag or Pd). In this embodiment, the plurality of coil conductor layers 12a, 12c, and 12e are plated conductors. The coil conductor layers 12a to 12e are disposed spaced apart from the end faces 2a and 2b, the main faces 2c and 2d, and the side faces 2e and 2f.

[0030] As shown in FIG. 2, the first connecting conductor 6 is disposed within the element body 2. The first connecting conductor 6 connects the external electrode 3 and the coil 5. The first connecting conductor 6 is a through-hole conductor. The first connecting conductor 6 extends in a first direction D1 and is connected to the external electrode 3 and one end of the coil 5. The first connecting conductor 6 is composed of a plurality of first connecting conductor layers 14a (see FIG. 3). In this embodiment, the first connecting conductor 6 has a rectangular cross section (cross section along the second direction D2 and the third direction D3) perpendicular to the extension direction (first direction D1). That is, the first connecting conductor 6 has a prismatic shape.

[0031] The second connecting conductor 7 is disposed within the element body 2. The second connecting conductor 7 connects the external electrode 4 and the coil 5. The second connecting conductor 7 is a through-hole conductor. The second connecting conductor 7 extends in the first direction D1 and is connected to the external electrode 4 and the other end of the coil 5. The second connecting conductor 7 is composed of multiple second connecting conductor layers 16a, 16b, 16c, 16d, and 16e (see FIG. 3). In this embodiment, the second connecting conductor 7 has a rectangular cross section (cross section along the second direction D2 and the third direction D3) perpendicular to the extension direction (first direction D1). That is, the second connecting conductor 7 has a prismatic shape.

[0032] 3, the coil component 1 includes multiple layers La, Lb, Lc, Ld, Le, Lf, Lg, and Lh. The coil component 1 is configured, for example, by stacking the layers La to Lh in order from the main surface 2c side. The coil component 1 according to this embodiment includes multiple layers Lc and multiple layers Lg.

[0033] The layer La is composed of the element body layer 10a. The layer La forms the main surface 2c of the element body 2.

[0034] Layer Lb is formed by combining an element layer 10b and a coil conductor layer 12a. The element layer 10b has a shape corresponding to the coil conductor layer 12a and is provided with a recess (not shown) into which the coil conductor layer 12a is fitted. The element layer 10b and the coil conductor layer 12a have a complementary relationship.

[0035] The layer Lc is formed by combining an element layer 10c, a coil conductor layer 12b, and a second connecting conductor layer 16a. The element layer 10c has shapes corresponding to the coil conductor layer 12b and the second connecting conductor layer 16a, and is provided with recesses (not shown) into which the coil conductor layer 12b and the second connecting conductor layer 16a are fitted. The element layer 10c, the coil conductor layer 12b, and the second connecting conductor layer 16a have a mutually complementary relationship.

[0036] The layer Ld is formed by combining an element layer 10d, a coil conductor layer 12c, and a second connecting conductor layer 16b. The element layer 10d has shapes corresponding to the coil conductor layer 12c and the second connecting conductor layer 16b, and is provided with recesses (not shown) into which the coil conductor layer 12c and the second connecting conductor layer 16b are fitted. The element layer 10d, the coil conductor layer 12c, and the second connecting conductor layer 16b have a complementary relationship with each other.

[0037] The layer Le is formed by combining an element layer 10e, a coil conductor layer 12d, and a second connecting conductor layer 16c. The element layer 10e has recesses (not shown) that have shapes corresponding to the coil conductor layer 12d and the second connecting conductor layer 16c and into which the coil conductor layer 12d and the second connecting conductor layer 16c are fitted. The element layer 10e, the coil conductor layer 12d, and the second connecting conductor layer 16c have a complementary relationship with each other.

[0038] The layer Lf is formed by combining an element layer 10f, a coil conductor layer 12e, and a second connecting conductor layer 16d. The element layer 10f has cutouts (not shown) that have shapes corresponding to the coil conductor layer 12e and the second connecting conductor layer 16d and into which the coil conductor layer 12e and the second connecting conductor layer 16d are fitted. The element layer 10f, the coil conductor layer 12e, and the second connecting conductor layer 16d have a complementary relationship.

[0039] The layer Lg is formed by combining an element layer 10g, a first connecting conductor layer 14a, and a second connecting conductor layer 16e. The element layer 10g has shapes corresponding to the first connecting conductor layer 14a and the second connecting conductor layer 16e, and is provided with recesses (not shown) into which the first connecting conductor layer 14a and the second connecting conductor layer 16e are fitted. The element layer 10g, the first connecting conductor layer 14a, and the second connecting conductor layer 16e have a mutually complementary relationship.

[0040] The layer Lh is formed by combining an element layer 10h, a metal base layer 8 of the external electrode 3, and a metal base layer 8 of the external electrode 4. The element layer 10h has a shape corresponding to each metal base layer 8, and is provided with recesses (not shown) into which each metal base layer 8 is fitted. The element layer 10h, the metal base layer 8 of the external electrode 3, and the metal base layer 8 of the external electrode 4 have a mutually complementary relationship. The layer Lh forms the main surface 2d of the element body 2.

[0041] Next, the external electrodes 3 and 4 will be described in detail. As shown in Fig. 4, the external electrodes 3 and 4 have a rectangular shape when viewed from the first direction D1, with the short side direction aligned in the second direction D2 and the long side direction aligned in the third direction D3. The external electrodes 3 and 4 are arranged apart from the outer edge of the main surface 2d.

[0042] The mounting surface (principal surface 2d) has a central region 2g disposed between the external electrodes 3 and 4 when viewed in a first direction D1 perpendicular to the mounting surface. The central region 2g has a rectangular shape. The outer surface 2s has a pair of peripheral edge portions 2h surrounding the external electrodes 3 and 4, respectively. The peripheral edge portions 2h have a rectangular ring shape.

[0043] As shown in FIG. 5, each of the external electrodes 3, 4 has a metal base layer 8 and a plating layer 9. The metal base layer 8 is provided on the outer surface 2s. The metal base layer 8 is provided only on the mounting surface (main surface 2d). The metal base layer 8 has an exposed surface 8a exposed from the element body 2. In this embodiment, the exposed surface 8a forms the same plane as the main surface 2d.

[0044] The base metal layer 8 has an embedded portion 8b embedded inside the element body 2. The embedded portion 8b is a portion located inside the element body 2 relative to the outer surface 2s (here, the main surface 2d). In this embodiment, the entire base metal layer 8 constitutes the embedded portion 8b. The embedded portion 8b has an opposing surface 8c opposing the exposed surface 8a and four side surfaces 8d adjacent to the exposed surface 8a. The side surfaces 8d extend toward the inside of the element body 2 so as to connect the exposed surface 8a and the opposing surface 8c. The angle formed between the side surface 8d and the peripheral edge portion 2h is, for example, less than 90 degrees. When the side surface 8d and the peripheral edge portion 2h are spaced apart from each other, the angle formed between an imaginary plane including the side surface 8d and an imaginary plane including the peripheral edge portion 2h may be the angle formed between the side surface 8d and the peripheral edge portion 2h. It can also be said that the angle formed between the side surface 8d and the exposed surface 8a is, for example, 90 degrees or greater. The angle formed between the side surface 8d and the peripheral edge portion 2h may be 90 degrees or more.

[0045] The metal base layer 8 is formed of a conductive material such as Ag, Cu, Ni, Sn, or Au. The metal base layer 8 is substantially free of glass components. The glass component content of the metal base layer 8 is, for example, less than 0.5%. Therefore, the area of ​​the metal base material on the surface of the metal base layer 8 is larger than that of a metal base layer containing a glass component. This makes plating easier.

[0046] The plating layer 9 covers the base metal layer 8. The plating layer 9 covers the entire exposed surface 8a. The plating layer 9 is provided on the outer edge 9a of the plating layer 9 and has a protrusion 9b that penetrates into the element body 2. The protrusion 9b covers the end of the side surface 8d that is closer to the exposed surface 8a. The protrusion 9b is provided, for example, on the outer edge 9a adjacent to the central region 2g. The protrusion 9b is provided, for example, around the entire periphery of the outer edge 9a.

[0047] The protrusions 9b are formed by the plating penetrating into the gaps between the soft magnetic metal particles P and the embedded portions 8b. The average depth to which the protrusions 9b penetrate into the element body 2 is, for example, equal to or greater than half the average particle diameter of the soft magnetic metal particles P.

[0048] The average particle diameter of the soft magnetic metal particles P can be obtained, for example, as follows: A cross-sectional photograph of the coil component 1 is obtained. The obtained cross-sectional photograph is subjected to image processing using software. The boundaries of the soft magnetic metal particles P are identified through image processing, and the area of ​​the soft magnetic metal particles P is determined. From the determined area of ​​the soft magnetic metal particles P, the particle diameter converted into a circle-equivalent diameter is determined. Here, the particle diameters of 100 or more soft magnetic metal particles P are calculated, and the particle size distribution of these soft magnetic metal particles P is determined. The particle diameter at 50% of the integrated value (d50) in the determined particle size distribution is defined as the "average particle diameter." The particle shape of the soft magnetic metal particles P is not particularly limited.

[0049] The average depth of the protrusions 9b can be obtained, for example, as follows: A cross-sectional photograph of the coil component 1 is obtained. The cross-sectional photograph can be obtained, for example, by photographing a cross section of the coil component 1 cut along a plane parallel to the side surfaces 2e and 2f and passing through the external electrodes 3 and 4. Multiple cross-sectional photographs are obtained while changing the position in the third direction D3. In the obtained cross-sectional photograph, a plane including the main surface 2d is used as a reference plane, and the length in the first direction D1 from the reference plane to the tip of the protrusion 9b is calculated as the depth of the protrusion 9b. The depths of up to four protrusions 9b can be calculated from one cross-sectional photograph. Here, the depths of the protrusions 9b are calculated from, for example, five or more cross-sectional photographs, and the average value of these depths is used as the "average depth" of the protrusions 9b.

[0050] Next, a description will be given of a method for manufacturing the coil component 1. The soft magnetic metal particles P are mixed with an insulating resin, a solvent, and the like to prepare a slurry containing the soft magnetic metal particles P. For example, the slurry is applied to a substrate (such as a PET film) by screen printing or doctor blade method, and a green sheet that will become the element layer 10a is formed on the substrate.

[0051] A conductive pattern is formed on the substrate by plating or screen printing. Then, a slurry is applied to the substrate by, for example, screen printing so as to fill in the periphery of the conductive pattern. This forms green sheets on the substrate that will become the multiple element layers 10b, 10c, 10d, 10e, 10f, 10g, and 10h.

[0052] In this embodiment, a first slurry for forming the first region R1 and a second slurry for forming the second region R2 are prepared as the above-mentioned slurries. The insulating resin and solvent contents of the first slurry are greater than the insulating resin and solvent contents of the second slurry. For example, the first slurry is used to form the element layer 10h and one element layer 10g adjacent to the element layer 10h. The second slurry is used to form the remaining element layers.

[0053] Next, the green sheets that will become the multiple element layers 10a-10h are transferred and stacked in this order, each with its conductor pattern. The green sheets are pressed in the stacking direction to form a laminate substrate. The laminate substrate is then cut into chips of a predetermined size using a cutting machine equipped with a rotary blade to form individual laminates. The individual laminates are then fired to form a laminate. The insulating resin and solvent in the slurry are burned away by firing, so gaps are formed between the soft magnetic metal particles P, P. Because the insulating resin and solvent content of the first slurry is greater than the insulating resin and solvent content of the second slurry, the size of the gaps in the first region R1 is greater than the size of the gaps in the second region R2.

[0054] Next, the laminate is immersed in a resin solution, and the resin is impregnated into the laminate and cured by heat. This forms the element body 2. Next, a plating layer 9 is formed by plating. At this time, since the volume of the gap is large in the first region R1, the protrusions 9b are easily formed. In this way, the coil component 1 is formed.

[0055] As described above, in the coil component 1 according to this embodiment, the plating layer 9 has the protrusions 9b that penetrate into the element body 2, which increases the surface area of ​​the plating layer 9 that bonds with the solder compared to a configuration in which the plating layer 9 does not have the protrusions 9b. This improves the bonding strength between the external electrodes 3, 4 and the solder.

[0056] Since the external electrodes 3, 4 are provided only on the main surface 2d, which is the mounting surface, it is important to improve the bonding strength between the external electrodes 3, 4 and the solder compared to a configuration in which the external electrodes 3, 4 are provided across multiple surfaces of the element body 2. Therefore, a configuration in which the plating layer 9 has protrusions 9b is particularly effective.

[0057] The base metal layer 8 has an embedded portion embedded inside the element body 2. This makes it difficult for the external electrodes 3 and 4 to peel off from the element body 2. This improves the mounting strength when the coil component 1 is mounted on a circuit board by soldering.

[0058] The angle formed between the peripheral edge 2h of the element body 2 and the side surface 8d of the embedded portion 8b is less than 90 degrees. This tends to result in large gaps between the soft magnetic metal particles P and the side surface 8d. The formation of protrusions 9b of the plating layer 9 in the large gaps further increases the surface area of ​​the plating layer 9 that bonds with the solder. This further improves the bonding strength between the external electrodes 3, 4 and the solder.

[0059] Since the base metal layer 8 does not contain a glass component, the area of ​​the base metal material on the surface of the base metal layer 8 is larger than in a configuration in which the base metal layer 8 contains a glass component. Therefore, plating can be easily performed.

[0060] The protrusions 9b are provided all around the outer edge 9a of the plating layer 9. This increases the surface area of ​​the plating layer 9 all around the outer edge 9a, further improving the bonding strength between the external electrodes 3, 4 and the solder.

[0061] By providing the protrusion 9b on the outer edge portion 9a adjacent to the central region 2g, the bonding strength between the external electrodes 3, 4 and the solder can be improved in the area that is likely to be subjected to stress when the coil component 1 is mounted, i.e., the area between the central region 2g and the external electrodes 3, 4.

[0062] The average depth to which the protrusions 9b penetrate into the element body 2 is at least half the average particle diameter of the soft magnetic metal particles P. This ensures that the bonding strength between the external electrodes 3, 4 and the solder is improved.

[0063] The average particle size of the soft magnetic metal particles P contained in the first region R1 is larger than the average particle size of the soft magnetic metal particles P contained in the second region R2. In the first region R1, the gaps between the soft magnetic metal particles P tend to become larger, making it easier to form protrusions 9b. In the second region R2, the gaps between the soft magnetic metal particles P tend to become smaller, making it possible to maintain the characteristics of the coil 5.

[0064] Second Embodiment A coil component 1 according to a second embodiment will be described with reference to Fig. 6 and Fig. 7. Fig. 6 is a perspective view of the coil component according to the second embodiment. Fig. 7 is a cross-sectional view of the coil component shown in Fig. 6. Fig. 8 is an exploded perspective view of the coil component shown in Fig. 6. As shown in Figs. 6 to 8, the coil component 20 includes an element body 22, external electrodes 23 and 24, a coil 25, a first connecting conductor 26, and a second connecting conductor 27. The coil component 20 is a laminated coil component.

[0065] The element body 22 has, for example, the same shape as the element body 2 of the coil device 1. The outer surface 22s of the element body 22 has a pair of end faces 22a and 22b, a pair of main faces 22c and 22d, and a pair of side faces 22e and 22f. The end faces 22a and 22b face each other. The main faces 22c and 22d face each other. The side faces 22e and 22f face each other. In this embodiment, the facing direction of the main faces 22c and 22d is defined as a first direction D1, the facing direction of the end faces 22a and 22b is defined as a second direction D2, and the facing direction of the side faces 22e and 22f is defined as a third direction D3. The first direction D1, the second direction D2, and the third direction D3 are approximately perpendicular to each other.

[0066] The end faces 22a, 22b extend in the first direction D1 to connect the principal faces 22c, 22d. The end faces 22a, 22b also extend in the third direction D3 to connect the side faces 22e, 22f. The principal faces 22c, 22d extend in the second direction D2 to connect the end faces 22a, 22b. The principal faces 22c, 22d also extend in the third direction D3 to connect the side faces 22e, 22f. The side faces 22e, 22f extend in the first direction D1 to connect the principal faces 22c, 22d. The side faces 22e, 22f also extend in the second direction D2 to connect the end faces 22a, 22b.

[0067] The main surface 22d is a mounting surface, and is the surface that faces another electronic device (not shown) when the coil component 1 is mounted on the other electronic device (for example, a circuit board or a laminated coil component). The end surfaces 22a and 22b are surfaces that are continuous with the mounting surface (i.e., the main surface 22d). The end surfaces 22a and 22b are surfaces that are adjacent to the mounting surface.

[0068] The end faces 22a and 22b have, for example, the same shape as the end faces 2a and 2b of the coil device 1. The main faces 22c and 22d have, for example, the same shape as the main faces 2c and 2d of the coil device 1. The side faces 22e and 22f have, for example, the same shape as the side faces 2e and 2f of the coil device 1.

[0069] The element body 22 is formed by stacking a plurality of element layers (magnetic layers) 30 in a first direction D1. That is, the stacking direction of the element body 22 is the first direction D1. A specific stacking configuration will be described later. In an actual element body 22, the plurality of element layers 30 are integrated to the extent that the boundaries between the layers are not visible. The element body 22 is made of, for example, the same material as the element body 2 of the coil device 1, and contains a plurality of soft magnetic metal particles P (see FIG. 5). Resin is present in at least some of the gaps between the soft magnetic metal particles P, P. The resin has electrical insulating properties and may be, for example, a silicone resin, a phenolic resin, an acrylic resin, or an epoxy resin.

[0070] The external electrodes 23 and 24 are provided on the element body 22 and connected to the coil 25. The external electrodes 23 and 24 are provided at both ends of the element body 22 in the second direction D2 and are spaced apart from each other in the second direction D2. The external electrodes 23 and 24 have the same shape.

[0071] The external electrode 23 is disposed on the end face 22a side of the element body 22. The external electrode 23 includes five electrode portions: a first electrode portion 23a located on the end face 22a, a second electrode portion 23b located on the main face 22c, a third electrode portion 23c located on the main face 22d, a fourth electrode portion 23d located on the side face 22e, and a fifth electrode portion 23e located on the side face 22f. The first electrode portion 23a, the second electrode portion 23b, the third electrode portion 23c, the fourth electrode portion 23d, and the fifth electrode portion 23e are connected at the ridges of the element body 22 and are electrically connected to one another. The external electrode 23 is formed on five surfaces: the end face 22a, the pair of main faces 22c and 22d, and the pair of side faces 22e and 22f. The first electrode portion 23a, the second electrode portion 23b, the third electrode portion 23c, the fourth electrode portion 23d, and the fifth electrode portion 23e are integrally formed.

[0072] In this embodiment, the edges (end faces) of the second electrode portion 23b and the third electrode portion 23c of the external electrode 23 extend along, for example, the third direction D3. The edge of the second electrode portion 23b is formed linearly on the main surface 22c. The edge of the third electrode portion 23c is formed linearly on the main surface 22d. The edges of the fourth electrode portion 23d and the fifth electrode portion 23e of the external electrode 23 extend along the first direction D1. The edge of the fourth electrode portion 23d is formed linearly on the side surface 22e. The edge of the fifth electrode portion 23e is formed linearly on the side surface 22f. The edges of the second electrode portion 23b, the third electrode portion 23c, the fourth electrode portion 23d, and the fifth electrode portion 23e may each be curved or uneven.

[0073] The external electrode 24 is disposed on the end face 22b side of the element body 22. The external electrode 24 includes five electrode portions: a first electrode portion 24a located on the end face 22b, a second electrode portion 24b located on the main face 22c, a third electrode portion 24c located on the main face 22d, a fourth electrode portion 24d located on the side face 22e, and a fifth electrode portion 24e located on the side face 22f. The first electrode portion 24a, the second electrode portion 24b, the third electrode portion 24c, the fourth electrode portion 24d, and the fifth electrode portion 24e are connected at the ridges of the element body 22 and are electrically connected to one another. The external electrode 24 is formed on five surfaces: the end face 22b, the pair of main faces 22c and 22d, and the pair of side faces 22e and 22f. The first electrode portion 24a, the second electrode portion 24b, the third electrode portion 24c, the fourth electrode portion 24d, and the fifth electrode portion 24e are integrally formed.

[0074] In this embodiment, the edges of the second electrode portion 24b and the third electrode portion 24c of the external electrode 24 extend along, for example, the third direction D3. The edge of the second electrode portion 24b is formed linearly on the main surface 22c. The edge of the third electrode portion 24c is formed linearly on the main surface 22d. The edges of the fourth electrode portion 24d and the fifth electrode portion 24e of the external electrode 24 extend along the first direction D1. The edge of the fourth electrode portion 24d is formed linearly on the side surface 22e. The edge of the fifth electrode portion 24e is formed linearly on the side surface 22f. The edges of the second electrode portion 24b, the third electrode portion 24c, the fourth electrode portion 24d, and the fifth electrode portion 24e may each be curved or uneven.

[0075] Each of the external electrodes 23, 24 has a metal base layer 28 and a plating layer 29. The metal base layer 28 is provided on the outer surface 22s. The metal base layer 28 of the external electrode 23 is provided on five surfaces, including the end surface 22a, the pair of main surfaces 22c, 22d, and the pair of side surfaces 22e, 22f. The metal base layer 28 of the external electrode 24 is provided on five surfaces, including the end surface 22a, the pair of main surfaces 22c, 22d, and the pair of side surfaces 22e, 22f. The metal base layer 28 is provided, for example, on the outside of the element body 22 and is not embedded inside the element body 22. The metal base layer 28 is formed of a conductive material such as Ag, Cu, Ni, Sn, or Au. The metal base layer 28 contains, for example, a glass component, but may not substantially contain a glass component.

[0076] The plating layer 29 covers the base metal layer 28. The plating layer 29 covers the entire outer surface of the base metal layer 28. The plating layer 29 is provided on an outer edge 29a of the plating layer 29 and has protrusions 29b that penetrate into the element body 2. The protrusions 29b are provided, for example, around the entire periphery of the outer edge 29a. The protrusions 29b may be provided, for example, on the outer edge 29a only on the main surface 22d (mounting surface) out of the main surfaces 22c, 22d and the side surfaces 22e, 22f.

[0077] The protrusions 29b are formed by plating entering into the gaps between the soft magnetic metal particles P (see FIG. 5). The average depth to which the protrusions 29b enter the element body 22 is, for example, ½ or more of the average particle diameter of the soft magnetic metal particles P.

[0078] The coil 25 is disposed within the element body 22. The coil 25 is composed of a plurality of coil conductors 32a to 32h (see FIG. 8). The plurality of coil conductors 32a to 32h are electrically connected to one another to form the coil 25 within the element body 22. The coil axis of the coil 25 is arranged along the first direction D1. Adjacent coil conductors 32a to 32h are electrically connected by through-hole conductors (not shown). The coil conductors 32a to 32h are disposed apart from the end faces 22a and 22b, the main faces 22c and 22d, and the side faces 22e and 22f.

[0079] The first connecting conductor 26 is disposed within the element body 22. The first connecting conductor 26 connects the external electrode 23 and the coil 25. The first connecting conductor 26 is connected to the external electrode 23 and one end of the coil 25. The first connecting conductor 26 is formed integrally with the coil conductor 32a.

[0080] The second connecting conductor 27 is disposed within the element body 22. The second connecting conductor 27 connects the external electrode 24 and the coil 25. The second connecting conductor 27 is connected to the external electrode 24 and the other end of the coil 25. The second connecting conductor 27 is formed integrally with the coil conductor 32a.

[0081] The coil conductors 32a to 32h, the first connecting conductor 26, and the second connecting conductor 27 are made of a conductive material typically used as a coil conductor. Examples of conductive materials that can be used include Ag, Cu, Au, Al, Pd, and Pd / Ag alloys. In this embodiment, the conductive material is Ag. The coil conductors 32a to 32h, the first connecting conductor 26, and the second connecting conductor 27 are formed as sintered bodies of conductive pastes containing the above conductive materials.

[0082] In the method of manufacturing coil component 20, the contents of insulating resin and solvent in the slurry may also be adjusted to increase the volume of the gap in the region of element body 22 that contacts outer edge portion 29a of plating layer 29.

[0083] As described above, in the coil component 20 according to this embodiment, the plating layer 29 has the protrusions 29b that penetrate into the element body 22, and therefore the surface area of ​​the plating layer 29 that bonds with the solder is increased compared to a configuration in which the plating layer 29 does not have the protrusions 29b. This can improve the bonding strength between the external electrodes 23, 24 and the solder.

[0084] The average particle size of the soft magnetic metal particles P in the region of the element body 22 near the main surface 22d may be larger than the average particle size of the soft magnetic metal particles P in other regions. In this case, the protrusions 29b on the main surface 22d are larger than the protrusions 29b on the main surface 22c and the side surfaces 22e and 22f. This further increases the surface area of ​​the plating layer 29 that bonds with the solder on the main surface 22d. As a result, the mounting strength can be improved.

[0085] Although the embodiments of the present invention have been described above, the present invention is not necessarily limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention.

[0086] In the above embodiment, the coil components 1 and 20 have been described as examples of coil components. However, the coil components are not limited to the coil components 1 and 20, and may be other coil components. For example, the number and shape of the coil conductors constituting the coils 5 and 25 are not limited.

[0087] 9 is a cross-sectional view of a coil device according to a first modified example of the first embodiment. As shown in the figure, the coil device 1A according to the first modified example differs from the coil device 1 in that the first region R1 includes a third region R3. The average particle size of the soft magnetic metal particles P in the third region R3 is larger than the average particle size of the soft magnetic metal particles P in the remaining region of the first region R1 and the average particle size of the soft magnetic metal particles in the second region R2. The volume of the gaps in the third region R3 is equivalent to the volume of the gaps in the remaining part of the first region R1 and is larger than the volume of the gaps in the second region R2.

[0088] The third region R3 is provided, for example, between the embedded portions 8b of the external electrodes 3, 4. The third region R3 includes the central region 2g as an outer surface. For example, the third region R3 includes a region of the element layer 10h that corresponds to the central region 2g. The thickness (length in the first direction D1) of the third region R3 is, for example, equivalent to the thickness (length in the first direction D1) of the external electrodes 3, 4.

[0089] When manufacturing the coil component 1A, in addition to the first and second slurries, a third slurry is prepared to form the third region R3. The contents of the insulating resin and solvent in the third slurry are equal to those in the first slurry and greater than those in the second slurry. The average particle size of the soft magnetic metal particles P in the third slurry is greater than the average particle size of the soft magnetic metal particles P in the first slurry and the average particle size of the soft magnetic metal particles P in the second slurry.

[0090] The plating layer 9 also has protrusions 9b in the coil component 1A, providing the same effect as the coil component 1. In the third region R3, the average particle diameter of the soft magnetic metal particles P is large, so the gaps between the side surface 8d and the soft magnetic metal particles P at the side surface 8d in contact with the third region R3 tend to become even larger. The formation of protrusions 9b of the plating layer 9 in the large gaps further increases the surface area of ​​the plating layer 9 that bonds with the solder. This further improves the bonding strength between the external electrodes 3, 4 and the solder.

[0091] Because the third region R3 includes the central region 2g as its outer surface, the protrusions 9b provided on the outer edge 9a adjacent to the central region 2g tend to be larger than the protrusions 9b provided on the outer edge 9a away from the central region 2g. Therefore, the average depth of the protrusions 9b provided on the outer edge 9a adjacent to the central region 2g can be made deeper than the average depth of the protrusions 9b provided on the outer edge 9a away from the central region 2g. In this way, when the average particle diameter of the soft magnetic metal particles P varies depending on the location where the protrusions 9b are provided, the average depth to which the protrusions 9b penetrate into the element body 2 is at least half the average particle diameter of the soft magnetic metal particles P provided adjacent to the protrusions 9b.

[0092] In the coil device 1A, the third region R3 is a part of the first region R1, but the third region R3 may be provided over the entire first region R1, in which case there is no need to prepare the first slurry.

[0093] FIG. 10 is a cross-sectional view of a coil component according to a second modified example of the first embodiment. As shown in the figure, the coil component 1B according to the second modified example differs from the coil component 1 in that the base metal layer 8 has a bent portion 8e. The bent portion 8e is bent toward the inside of the element body 2. When viewed from the third direction D3, the bent portion 8e protrudes from the end of the exposed surface 8a on the side of the central region 2g toward the center of the element body 2 in the second direction D2 and the center of the element body 2 in the first direction D1. When viewed from the first direction D1, the bent portion 8e overlaps with the central region 2g. The bent portion 8e is embedded inside the element body 2. The entire base metal layer 8, including the bent portion 8e, constitutes the embedded portion 8b.

[0094] In coil component 1B, plating layer 9 also has protrusions 9b, providing the same effect as coil component 1. In coil component 1B, base metal layer 8 has bent portions 8e embedded inside element body 2, making it even more difficult for external electrodes 3, 4 to peel off from element body 2. This further improves mounting strength when coil component 1B is mounted on a circuit board by soldering. Due to bending stress during mounting, cracks are likely to occur in element body 2, originating from the portion between central region 2g and external electrodes 3, 4. In coil component 1B, bent portions 8e are provided in locations where cracks are likely to occur. This makes it possible to suppress cracks.

[0095] The bent portion 8e includes one of the four side surfaces 8d. The angle formed between the side surface 8d of the bent portion 8e and the peripheral edge portion 2h is smaller than the angles formed between the other three side surfaces 8d and the peripheral edge portion 2h, for example. This tends to increase the gap between the side surface 8d of the bent portion 8e and the soft magnetic metal particles P. The formation of the protrusions 9b of the plating layer 9 in the large gaps further increases the surface area of ​​the plating layer 9 that bonds with the solder. This further improves the bonding strength between the external electrodes 3, 4 and the solder.

[0096] Because the bent portion 8e is provided adjacent to the end portion of the exposed surface 8a on the central region 2g side, the protrusions 9b provided on the outer edge portion 9a adjacent to the central region 2g tend to be larger than the protrusions 9b provided on the outer edge portion 9a away from the central region 2g. Therefore, similar to the coil device 1A, the average depth of the protrusions 9b provided on the outer edge portion 9a adjacent to the central region 2g can be made deeper than the average depth of the protrusions 9b provided on the outer edge portion 9a away from the central region 2g. [Explanation of symbols]

[0097] DESCRIPTION OF SYMBOLS 1, 1A, 1B... coil component, 2... element body, 2a, 2b... end faces, 2d... main surface (mounting surface), 2g... central region, 2h... peripheral portion, 2s... outer surface, 3, 4... external electrode, 5... coil, 8... base metal layer, 8b... embedded portion, 9... plating layer, 9a... outer edge portion, 9b... protrusion portion, 20... coil component, 22... element body, 22a, 22b... end faces, 22d... main surface (mounting surface), 22s... outer surface, 23, 24... external electrode, 25... coil, 28... base metal layer, 29... plating layer, 29a... outer edge portion, 29b... protrusion portion, P... soft magnetic metal particle.

Claims

1. an element body including soft magnetic metal particles; a coil disposed within the element body; an external electrode connected to the coil, the external electrodes each have a metal base layer provided on an outer surface of the element body and a plating layer covering the metal base layer; the plating layer has a protrusion provided on an outer edge of the plating layer and extending into the element body. Coil parts.

2. the outer surface has a mounting surface; the external electrodes are provided only on the mounting surface; The coil component according to claim 1 .

3. the base metal layer has a buried portion buried inside the element body; The coil component according to claim 1 or 2.

4. the outer surface includes a peripheral edge of the external electrode; the embedded portion has an exposed surface exposed from the outer surface and a side surface adjacent to the exposed surface, The angle between the peripheral edge and the side surface is 90 degrees or less. The coil component according to claim 3 .

5. The metal base layer does not contain a glass component. The coil component according to claim 1 or 2.

6. The protrusion is provided around the entire outer edge of the plating layer. The coil component according to claim 1 or 2.

7. the outer surface has a mounting surface and a pair of end surfaces adjacent to the mounting surface and facing each other, the pair of external electrodes are provided on the mounting surface spaced apart from each other in the opposing direction of the pair of end surfaces, the mounting surface has a central region disposed between the pair of external electrodes when viewed in a direction perpendicular to the mounting surface, The protrusion is provided on an outer edge of the plating layer adjacent to the central region. The coil component according to claim 1 or 2.

8. the element body has a first region provided in contact with the external electrode and a second region provided in contact with the coil, the average particle size of the soft magnetic metal particles contained in the first region is larger than the average particle size of the soft magnetic metal particles contained in the second region; The coil component according to claim 1 or 2.

9. the average depth to which the protrusions penetrate into the element body is equal to or greater than half the average particle diameter of the soft magnetic metal particles; The coil component according to claim 1 or 2.

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