COIL COMPONENT

TECHNICAL FIELD

The present disclosure relates to a coil component. This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2022-000383, filed on Jan. 5, 2022, the entire contents of which are incorporated herein by reference.

BACKGROUND

Japanese Patent Application Laid-Open No. 2013-38263discloses a multilayer inductor including a magnetic portion formed by laminating a plurality of magnetic layers, a coil disposed in the magnetic portion, and external terminals provided at both end portions of the magnetic portion and connected to the coil.

SUMMARY

An object of the present disclosure is to provide a coil component capable of improving the junction strength between an internal conductor and an external electrode.

A coil component according to a first aspect of the present disclosure includes: an element body; a coil including a plurality of coil conductors disposed in the element body and electrically connected to each other; an external electrode disposed on the element body; and a connection conductor that connects the coil and the external electrode. The connection conductor has an end portion exposed from an outer surface of the element body and connected to the external electrode. The end portion has a shape extending outward over an entire circumference.

In the coil component according to the first aspect of the present disclosure, the connection conductor has the shape expanding outward over the entire circumference in the end portion. This increases the junction area between the connection conductor and the external electrode. Therefore, the junction strength between the connection conductor, which is an internal conductor, and the external electrode can be improved.

A coil component according to a second aspect of the present disclosure includes: an element body; a coil including a plurality of coil conductors disposed in the element body and electrically connected to each other; an external electrode disposed on the element body; and a connection conductor that connects the coil and the external electrode.

The connection conductor has an end portion exposed from an outer surface of the element body and connected to the external electrode. The end portion has a shape in which a cross-sectional area of the end portion gradually increases toward the external electrode.

In the coil component according to the second aspect of the present disclosure, the end portion of the connection conductor has the shape in which the cross-sectional area of the end portion gradually increases toward the external electrode. This increases the junction area between the connection conductor and the external electrode. Therefore, the junction strength between the connection conductor, which is an internal conductor, and the external electrode can be improved.

The element body may include a plurality of element body layers laminated in the first direction. The element body layer may include a plurality of soft magnetic metal particles.

A coil component according to a third aspect of the present disclosure includes: an element body; a coil including a plurality of coil conductors disposed in the element body and electrically connected to each other; an external electrode disposed on the element body; and a connection conductor that connects the coil and the external electrode. The element body includes a plurality of element body layers laminated in a first direction. Each of the plurality of element body layers includes a plurality of soft magnetic metal particles. The connection conductor has an end portion exposed from an outer surface of the element body and connected to the external electrode. A length of the end portion in the first direction is longer than a length of each of the plurality of coil conductors in the first direction. Two or more soft magnetic metal particles are disposed along the first direction between a coil conductor of the plurality of coil conductors and the connection conductor that are adjacent to each other in the first direction.

In the coil component according to the third aspect of the present disclosure, the length of the first direction of the end portion of the connection conductor is longer than the length of the first direction of the coil conductor. This increases the junction area between the connection conductor and the external electrode. Therefore, the junction strength between the connection conductor, which is an internal conductor, and the external electrode can be improved. Further, two or more soft magnetic metal particles are disposed between the connection conductor and the coil conductor along the first direction. As a result, the interlayer withstand voltage between the connection conductor and the coil conductor can be improved.

A line width of the end portion may be greater than a line width of each of the plurality of coil conductors when viewed from the first direction. In this case, the junction area between the connection conductor and the external electrode is reliably increased. Therefore, the junction strength between the connection conductor and the external electrode can be reliably improved.

The external electrode may be a conductive resin layer. In this case, the density of metal particles in the external electrode is lower than that in a configuration in which the external electrode is a sintered metal layer. Therefore, the stray capacitance between the external electrode and the coil conductor can be suppressed.

A length of the end portion in a length direction of the connection conductor may be half or less of a separation distance between the plurality of coil conductors and the external electrode. In this case, a withstand voltage between the end portion and the coil conductor may be secured.

An outer surface of the end portion may be curved so as to be recessed inward of the connection conductor in a cross section orthogonal to the outer surface on which the end portion is exposed. In this case, it is easy to secure a withstand voltage between the end portion and the coil conductor.

A separation distance between the plurality of coil conductors and the external electrode may be longer than a separation distance between adjacent coil conductors of the plurality of coil conductors. In this case, since the voltage applied between the coil conductor and the external electrode is larger than the voltage applied between the adjacent coil conductors, it is easy to secure the withstand voltage of the coil.

The connection conductor may be a plated conductor. In this case, the density of the connection conductor can be increased as compared with the case where the connection conductor is a sintered metal conductor. Therefore, the junction area between the connection conductor and the external electrode can be further increased.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating a coil component according to an embodiment.

FIG. 2 is an exploded perspective view of the coil component shown in FIG. 1. FIG. 3 is a cross-sectional view of the coil component shown in

FIG. 1.

FIG. 4 is a perspective view showing a first end portion of a first connection conductor.

FIG. 5 is a partially enlarged view of FIG. 3.

DETAILED DESCRIPTION

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and redundant description is omitted.

As shown in FIG. 1, a coil component 1 according to the embodiment includes an element body 2, a first external electrode 4, a second external electrode 5, a first electrode part 6, and a second electrode part 7.

The element body 2 has a substantially rectangular parallelepiped shape. The rectangular parallelepiped shape includes a rectangular parallelepiped shape in which corner portions and ridge portions are chamfered and a rectangular parallelepiped shape in which corner portions and ridge portions are rounded. The element body 2 has, as its outer surface, a pair of end surfaces 2a and 2b opposing each other, a pair of main surfaces 2c and 2d opposing each other, and a pair of side surfaces 2e and 2f opposing each other. An opposing direction in which the pair of main surfaces 2c and 2d are opposed to each other is a first direction D1. An opposing direction in which the pair of end surfaces 2a and 2b are opposed to each other is a second direction D2. An opposing direction in which the pair of side surfaces 2e and 2f are opposed to each other is a third direction D3. In the present embodiment, the first direction D1 is a height direction of the element body 2. The second direction D2 is a longitudinal direction of the element body 2 and is orthogonal to the first direction D1. The third direction D3 is a width direction of the element body 2 and is orthogonal to the first direction D1 and the second direction D2.

The pair of end surfaces 2a and 2b extends in the first direction D1 so as to connect between the pair of main surfaces 2c and 2d. The pair of end surfaces 2a and 2b also extends in the third direction D3 (short side direction of the pair of main surfaces 2c and 2d). The pair of side surfaces 2e and 2f extends in the first direction D1 so as to connect between the pair of main surfaces 2c and 2d. The pair of side surfaces 2e and 2f also extends in the second direction D2 (long side direction of the pair of end surfaces 2a and 2b). The main surface 2d may be defined as a mounting surface that faces another electronic device (for example, a circuit board or an electronic component) when the coil component 1 is mounted on the other electronic device.

As shown in FIG. 2, the element body 2 has a plurality of element body layers 10a to 10p that are laminated in the first direction D1. The coil component 1 is a multilayer coil component. Each of the element body layers 10a to 10p is laminated in this order in the first direction D1. That is, the first direction D1 is the laminating direction. In the actual element body 2, the element body layers 10a to 10p are integrated to such an extent that the boundary between the layers cannot be visually recognized. In FIG. 2, each of the element body layer 10a to 10p is illustrated one by one, but a plurality of element body layers 10a and a plurality of element body layers 10o are laminated. The main surface 2c is constituted by the main surface of the element body layer 10a located at the laminated end. The main surface 2d is constituted by the main surface of the element body layer 10p.

The thicknesses of each element body layer 10a to 10p (lengths of the first direction D1) are, for example, 1 μm or more 100 μm or less.

In FIG. 2, the thicknesses of the element body layers 10a to 10p are shown to be equal, but the element body layers 10b, 10d, 10f, 10h, 10j, 10l, and 10n are thicker than the element body layers 10c 10e 10g 10i 10k 10m and 10o. The coil conductors 21 to 25, a first connection conductor 8, and a second connection conductor 9 described later are provided in the element body layers 10b, 10d, 10f, 10h, 10j, 10l, and 10n. The through-hole conductors 31 to 36 described later are provided in the element body layers 10c 10e 10g 10i 10k 10m and 10o. The thicknesses of the element body layers 10b, 10d, 10f, 10h, 10j, 10l, and 10n are equal to each other in the present embodiment and are, for example, 15 μm or more 100 μm or less. The thicknesses of the element body layers 10c, 10e, 10g, 10i, 10k, 10m, and 10o are equal to each other in the present embodiment and are, for example, 1 μm or more 15 μm or less.

Each of the element body layers 10a to 10p includes a plurality of soft magnetic metal particles M (see FIG. 5). The soft magnetic metal particles M is made of a soft magnetic alloy (soft magnetic material). The soft magnetic alloy is, for example, an Fe—Si-based alloy. When the soft magnetic alloy is the Fe—Si-based alloy, the soft magnetic alloy may contain P. The soft magnetic alloy may be, for example, an Fe—Ni—Si—M-based 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.

The soft magnetic metal particles M are coupled to each other in each of the element body layers 10a to 10p. The coupling between the soft magnetic metal particles M is realized by coupling between oxide films formed on surfaces of the soft magnetic metal particles M, for example. The soft magnetic metal particles M are electrically insulated from each other by coupling of oxide films in each of the element body layers 10a to 10p. The thicknesses of the oxide films are, for example, 5 nm or more 60 nm or less. The oxide film may include one or more layers.

The element body 2 contains resins. The resins are present between the plurality of soft magnetic metal particles M. The resin is an insulating resin having electrical insulating properties. The insulating resin includes, for example, silicone resin, phenol resin, acrylic resin, or epoxy resin.

As shown in FIG. 3, in the element body 2, a part of the main surface 2d forms steps. To be specific, a portion close to each of the end surfaces 2a and the end surface 2b is recessed toward the main surface 2c from the central portion in the main surface 2d.

As shown in FIGS. 1 and 3, the first external electrode 4 and the second external electrode 5 are disposed on the element body 2. The first external electrode 4 and the second external electrode 5 are disposed on an outer surface of the element body 2. The first external electrode 4 is located at one end portion of the second direction D2 of the element body 2. The second external electrode 5 is located at the other end portion of the second direction D2 of the element body 2. The first external electrode 4 and the second external electrode 5 are spaced apart from each other in the second direction D2.

The first external electrode 4 includes a first electrode portion 4a located on the end surface 2a, a second electrode portion 4b located on the main surface 2c, a third electrode portion 4c located on the main surface 2d, a fourth electrode portion 4d located on the side surface 2e, and a fifth electrode portion 4e located on a side surface 2f. The first electrode portion 4a extends along the first direction D1 and the third direction D3 and has a rectangular shape when viewed from the second direction D2. The second electrode portion 4b extends along the second direction D2 and the third direction D3 and has a rectangular shape when viewed from the first direction D1. The third electrode portion 4c extends along the second direction D2 and the third direction D3 and has a rectangular shape when viewed from the first direction D 1. The fourth electrode portion 4d extends along the first direction D1 and the second direction D2 and has a rectangular shape when viewed from the third direction D3. The fifth electrode portion 4e extends along the first direction D1 and the second direction D2 and has a rectangular shape when viewed from the third direction D3.

The first electrode portion 4a, the second electrode portion 4b, the third electrode portion 4c, the fourth electrode portion 4d, and the fifth electrode portion 4e are connected at the ridges of the element body 2, and are electrically connected to each other. The first external electrode 4 is formed on five surfaces that include the end surface 2a, the pair of main surfaces 2c and 2d, and the pair of side surfaces 2e and 2f. The first electrode portion 4a, the second electrode portion 4b, the third electrode portion 4c, the fourth electrode portion 4d, and the fifth electrode portion 4e are integrally formed.

The second external electrode 5 includes a first electrode portion 5a located on the end surface 2b, a second electrode portion 5b located on the main surface 2c, a third electrode portion 5c located on the main surface 2d, a fourth electrode portion 5d located on the side surface 2e, and a fifth electrode portion 5e located on the side surface 2f The first electrode portion 5a extends along the first direction D1 and the third direction D3 and has a rectangular shape when viewed from the second direction D2. The second electrode portion 5b extends along the second direction D2 and the third direction D3 and has a rectangular shape when viewed from the first direction D1. The third electrode portion 5c extends along the second direction D2 and the third direction D3 and has a rectangular shape when viewed from the first direction D 1. The fourth electrode portion 5d extends along the first direction D1 and the second direction D2 and has a rectangular shape when viewed from the third direction D3. The fifth electrode portion 5e extends along the first direction D1 and the second direction D2 and has a rectangular shape when viewed from the third direction D3.

The first electrode portion 5a, the second electrode portion 5b, the third electrode portion 5c, the fourth electrode portion 5d, and the fifth electrode portion 5e are connected at the ridges of the element body 2, and are electrically connected to each other. The second external electrode 5 are formed on five surfaces that include the end surface 2b, the pair of main surfaces 2c and 2d, and the pair of side surfaces 2e and 2f. The first electrode portion 5a, the second electrode portion 5b, the third electrode portion 5c, the fourth electrode portion 5d, and the fifth electrode portion 5e are integrally formed.

The first external electrode 4 and the second external electrode 5 are conductive resin layers. As the conductive resin, a thermosetting resin mixed with a conductive material, an organic solvent and the like is used. As the conductive material, for example, a conductive filler is used. The conductive filler is a metal powder. As the metal powder, for example, Ag powder is used. As the thermosetting resin, for example, a phenol resin, an acrylic resin, a silicone resin, an epoxy resin, or a polyimide resin is used.

The first electrode part 6 and the second electrode part 7 are located in the main surface 2d so as to be spaced apart from each other in the second direction D2. The first electrode part 6 and the second electrode part 7 have rectangular shapes when viewed from the first direction D1 and extend along the second direction D2 and the third direction D3. The first electrode part 6 and the second electrode part 7 are provided on the entire main surface 2d of the third direction D3.

The first electrode part 6 is provided so as to fill the step provided on the end surface 2a side of the main surface 2d. The first electrode part 6 is flush with the main surface 2d, the end surface 2a, the side surface 2e, and the side surface 2f It can be said that the first electrode part 6 is buried in the element body 2 so as to be exposed from the main surface 2d, the end surface 2a, the side surface 2e and the side surface 2f. The second electrode part 7 is provided so as to fill the step provided on the end surface 2b side of the main surface 2d. The second electrode part 7 is flush with the main surface 2d, the end surface 2b, the side surface 2e, and the side surface 2f It can be said that the second electrode part 7 is buried in the element body 2 so as to be exposed from the main surface 2d, the end surface 2b, the side surface 2e and the side surface 2f.

As shown in FIG. 2, the first electrode part 6 and the second electrode part 7 are provided so as to sandwich the element body layer 10p in the second direction D2. The first electrode part 6, the second electrode part 7, and the element body layer 10p have the same thicknesses, that is, the same lengths in the first direction D1. The first electrode part 6 and the second electrode part 7 are, for example, printing pastes or plated conductors. The first electrode part 6 and the second electrode part 7 contain electrically conductive material. The conductive material is, for example, Ag, Pd, Cu, Al, or Ni.

As shown in FIGS. 2 and 3, the coil component 1 further includes a coil 3, the first connection conductor 8 and the second connection conductor 9.

The coil 3 is disposed in the element body 2. In the present embodiment, the coil 3 is disposed at the center of the element body 2 in the second direction D2 and the third direction D3. In other words, a separation distance between the coil 3 and the end surface 2a is equal to a separation distance between the coil 3 and the end surface 2b. A separation distance between the coil 3 and the side surface 2e is equal to a separation distance between the coil 3 and the side surface 2f. In the present specification, the separation distance means the shortest separation distance.

The coil 3 includes coil conductors 21 to 25 and through-hole conductors 31 to 36 which are electrically connected to each other. The coil conductors 21 to 25 and the through-hole conductors 31 to 36 are inner conductors disposed inside the coil 3 together with the first connection conductor 8 and the second connection conductor 9. The internal conductor is, for example, a plated conductor. The inner conductor includes an electrically conductive material. The conductive material is, for example, Ag, Pd, Cu, Al, or Ni. The inner conductors are made of the same material, for example. The inner conductor is made of, for example, the same material as the first electrode part 6 and the second electrode part 7.

The coil axes of the coils 3 are provided along the first direction D1. The coil conductors 21 to 25 are arranged so as to at least partially overlap each other when viewed from the first direction D1. One end portion 21a of a coil conductor 21 constitutes one end portion 3a of the coil 3. The other end portion 21b of the coil conductor 21 is connected by a through-hole conductor 32 to one end portion 22a of a coil conductor 22. The other end portion 22b of the coil conductor 22 is connected by a through-hole conductor 33 to one end portion 23a of a coil conductor 23. The other end portion 23b of the coil conductor 23 is connected by a through-hole conductor 34 to one end portion 24a of a coil conductor 24. The other end portion 24b of the coil conductor 24 is connected by a through-hole conductor 35 to one end portion 25a of a coil conductor 25. The other end portion 25b of the coil conductor 25 constitutes the other end portion 3b of the coil 3.

Each of the end portions 21a to 25a and 21b to 25b of the coil conductors 21 to 25 is formed in a circular shape when viewed from the first direction D1. When viewed from the first direction D1, the diameter of each end portion 21a to 25a and 21b to 25b is greater than a line width W1 of each coil conductor 21 to 25. The line width W1 is line widths of the portions other than the end portions 21a to 25a and 21b to 25b of the coil conductors 21 to 25. Since each end portion 21a to 25a and 21b to 25b is enlarged, the end portions 21a to 25a and 21b to 25b can be easily connected to the through-hole conductors 31 to 36. The line width W1 is, for example, 5 μm or more 300 μm or less. The diameter of each end portion 21a to 25a and 21b to 25b is equivalent to the diameters of each through-hole conductor 31 to 36, and is, for example, 10 μm or more 300 μm or less.

The coil conductor 21 is provided on the element body layer 10d. The coil conductor 22 is provided on the element body layer 10f. The coil conductor 23 is provided on the element body layer 10h. The coil conductor 24 is provided on the element body layer 10j. The coil conductor 25 is provided on the element body layer 10l. The coil conductors 21 to 25 are provided so as to pass through the corresponding element body layer 10d, 10f, 10h, 10j, and 10l in the thickness direction (that is, the first direction D1) thereof.

The lengths L1 of the coil conductors 21 to 25 in the first direction D1 are equal to each other in present embodiment. The lengths L1 of the coil conductors 21 to 25 in the first direction D1 are equivalent to the thicknesses of the corresponding element body layer 10d, 10f, 10h, 10_jand 10l.

The through-hole conductor 31 is provided on the element body layer 10c. The through-hole conductor 32 is provided on the element body layer 10e. The through-hole conductor 33 is provided on the element body layer 10g. The through-hole conductor 34 is provided on the element body layer 10i. The through-hole conductor 35 is provided on the element body layer 10k. The through-hole conductor 36 is provided on the element body layer 10m. Each of the through-hole conductors 31 to 36 is provided so as to pass through the corresponding element body layer 10c, 10e, 10g, 10i, 10k, and 10m in the thickness direction (that is, the first direction D1) thereof.

The lengths L2 of the through-hole conductors 31 to 36 in the first direction D1 are equal to each other in present embodiment. The lengths L2 of the through-hole conductors 31 to 36 in the first direction D1 are equal to the thicknesses of the corresponding element body layers 10c, 10e, 10g, 10i, 10k, and 10m. The lengths L2 are equal to each of a separation distance between adjacent coil conductors 21 to 25, a separation distance between the first connection conductor 8 and the coil conductor 21, and a separation distance between the second connection conductor 9 and the coil conductor 25. The lengths L1 are longer than the lengths L2.

The first connection conductor 8 connects one end portion 3a of the coil 3 to the first electrode portion 4a of the first external electrode 4. The first connection conductor 8 extends in the second direction D2. The first connection conductor 8 has a first end portion 8a and a second end portion 8b. The first end portion 8a is exposed from the end surface 2a and connected to the first electrode portion 4a. The first end portion 8a includes a connection surface 8c in contact with the first electrode portion 4a.

The second end portion 8b is connected to one end portion 3a of the coil 3 by the through-hole conductor 31. The second end portion 8b is formed in a circular shape when viewed from the first direction D1. As viewed from the first direction D1, the diameter of the second end portion 8b is greater than the line widths of portions other than both end portions 8a and 8b of the first connection conductor 8. Since the second end portion 8b is enlarged in this manner, the second end portion 8b and the through-hole conductor 31 are easily connected. When viewed from the first direction D1, the line widths of the portions other than both end portions 8a and 8b of the first connection conductor 8 are equivalent to the line width W1 of each coil conductors 21 to 25.

The second connection conductor 9 connects the other end portion 3b of the coil 3 and the first electrode portion 5a of the second external electrode 5. The second connection conductor 9 extends in the second direction D2. The second connection conductor 9 has a first end portion 9a and a second end portion 9b. The first end portion 9a is exposed from the end surface 2b and connected to the first electrode portion 5a. The first end portion 9a includes a connection surface 9c in contact with the first electrode portion 5a.

The second end portion 9b is connected to the other end portion 3b of the coil 3 by the through-hole conductor 36. The second end portion 9b is formed in a circular shape when viewed from the first direction D1. As viewed from the first direction D1, the diameter of the second end portion 9b is greater than the line widths of portions other than both end portions 9a and 9b of the second connection conductor 9.

Since the second end portion 9b is enlarged in this manner, the second end portion 9b and the through-hole conductor 36 are easily connected. When viewed from the first direction D1, the line widths of the portions other than both end portions 9a and 9b of the second connection conductor 9 are equivalent to the line width W1 of each coil conductor 21 to 25.

As shown in FIGS. 2 to 4, the first end portion 8a of the first connection conductor 8 has a shape in which the cross-sectional area of the first end portion 8a (cross-sectional area parallel to the end surface 2a or cross-sectional area orthogonal to the second direction D2, which is the longitudinal direction of the first connection conductor 8) gradually increase toward the first electrode portion 4a. The first connection conductor 8 has a shape that spreads outward over the entire circumference of the first end portion 8a. The first end portion 8a has a tapered shape gradually expanding outward over the entire circumference toward the first electrode portion 4a. The outer surface 8d of the first end portion 8a (see FIG. 5) has a tapered shape in all cross sections orthogonal to the end surface 2a. The outer surface 8d is curved so as to be recessed to the inside of the first connection conductor 8 in a cross section orthogonal to the end surface 2a, and has an R shape. The first end portion 8a has a tapered shape throughout the second direction D2.

The length L3 (maximum length) of the first end portion 8a in the first direction D1 is longer than the lengths L1 of coil conductors 21 to 25 in the first direction D1. The length L3 is, for example, 5 μm or more 150 μm or less. When viewed from the first direction D1, a line width W2 of the first end portion 8a (the maximum length of the first end portion 8a in the third direction D3) is greater than the line widths W1 of the coil conductors 21 to 25. The line width W2 is, for example, 10 μm or more 400 μm or less.

A length L4 of the first end portion 8a in the longitudinal direction (the second direction D2) of the first connection conductor 8 is half or less of a separation distance L5 between coil conductors 21 to 25 and the first external electrode 4. The first end portion 8a does not overlap the coil conductors 21 to 25 when viewed from the first direction D1. The length L4 is, for example, equivalent to the curvature radius of the outer surface 8d in a cross section orthogonal to the end surface 2a. The length L4 is, for example, 5 μm or more and 30 μm or less. The separation distance L5 is, for example, 30 μm or more 150 μm or less.

The lengths L2 are shorter than the separation distance L5. The lengths L2 are the lengths of the through-hole conductors 31 to 36 as described above, and are equivalent to the thicknesses of the element body layers 10c, 10e, 10g, 10i, 10k, and 10m. Therefore, the lengths L2 are equal to the separation distance between two adjacent internal conductors among the coil conductors 21 to 25, the first connection conductor 8, and the second connection conductor 9.

Although a perspective view of the second connection conductor 9 is omitted, the first end portion 9a of the second connection conductor 9 has the same shape as the first end portion 8a of the first connection conductor 8. The first end portion 9a has a shape in which the cross section of the first end portion 9a (the cross section parallel to the end surface 2b or the cross section perpendicular to the second direction D2, which is the longitudinal direction of the second connection conductor 9) gradually increases toward the first electrode portion 5a. The second connection conductor 9 has a shape that spreads outward over the entire circumference of the first end portion 9a. The first end portion 9a has a tapered shape gradually expanding outward over the entire circumference toward the first electrode portion 5a. The outer surface of the first end portion 9a has a tapered shape in all cross sections perpendicular to the end surface 2b. The outer surface of the first end portion 9a is curved so as to be recessed toward the inside of the second connection conductor 9 in a cross section orthogonal to the end surface 2b, and has an R shape. The first end portion 9a has a tapered shape throughout the second direction D2.

The length L6 (maximum lengths) of the first end portion 9a in the first direction D1 is longer than the lengths L1. The lengths L6 are equivalent to the lengths L3. When viewed from the first direction D1, the line width W3 of the first end portion 9a (the maximum length of the first end portion 9a in the third direction D3) is greater than the line widths W1 of the coil conductors 21 to 25. The length L7 of the first end portion 9a in the longitudinal direction (the second direction D2) of the second connection conductor 9 is half or less of a separation distance L8 between the coil conductors 21 to 25 and the second external electrode 5. The length L7 is equivalent to the lengths L4. The separation distance L8 is equivalent to the separation distance L5. The first end portion 9a does not overlap the coil conductors 21 to 25 when viewed from the first direction D1. The length L7 is, for example, equal to the curvature radius of the outer surface of the first end portion 9a in a cross-section orthogonal to the end surface 2b.

As shown in FIG. 5, two or more soft magnetic metal particles M are arranged along the first direction D1 between the coil conductor 21 and the first connection conductor 8 adjacent to each other in the first direction D1. In FIG. 5, hatching of resins present between the soft magnetic metal particles M portions is omitted. Although a partially enlarged view of the second connection conductor 9 is not shown, two or more soft magnetic metal particles M are also arranged along the first direction D1 between the coil conductor 25 and the second connection conductor 9 adjacent to each other in the first direction D1.

Next, a method of manufacturing the coil component 1 will be described.

The soft magnetic metal particles M, insulating resins, solvents and the like are mixed to prepare slurry. The prepared slurry is provided on a base material (for example, a polyethylene terephthalate film) by, for example, a screen printing method or a doctor-blade method to form a plurality of green sheets serving as the plurality of element body layers 10a on the base material. Similarly, a plurality of green sheets serving as the plurality of element body layers 10o is formed on the base material.

A conductor pattern to be the first connection conductor 8 is formed on a base material by screen printing or plating. Subsequently, the slurry is applied onto the base material by, for example, the screen printing method so as to fill the periphery of the conductor pattern. Thus, a plurality of green sheets serving as the plurality of element body layers 10b is formed on the base material. A plurality of green sheets which becomes the plurality of element body layers 10c to 10n and 10p is also formed so as to fill the periphery after forming the corresponding conductor pattern on a base material.

Next, green sheets to be element body layers 10a to 10p are transferred and laminated together with the conductor pattern in this order. The green sheets are pressed from the laminating direction to form a laminate. Subsequently, the laminate of the green sheets is fired to form a laminate substrate. Subsequently, the laminate substrate is cut into chips of a predetermined size by a cutting machine including a rotary blade to form individualized laminates.

In the above-described step of forming the conductor pattern, the conductor pattern serving as the first connection conductor 8 and the second connection conductor 9 is formed so as to cover a portion serving as a cutting margin in the step of cutting the laminate substrate. For example, one of adjacent conductor patterns may be inverted so that conductor patterns serving as the first connection conductor 8 are continuous through the portion serving as the cutting margin, and conductor patterns serving as the second connection conductor 9 may be continuous through the portion serving as the cutting margin. The first end portion 8a and the first end portion 9a can be formed into a desired shape by scraping the conductor of the cutting margin by the rotary blade.

The shapes of the first end portion 8a and the first end portion 9a are appropriately adjusted according to cutting conditions such as the materials of the element body 2 and the conductor and the rotation speed of the rotary blade.

Subsequently, the laminate is immersed in a resin solution to impregnate the laminate with the resin. Thus, the element body 2 is formed. Resin electrode layers serving as the first external electrode 4 and the second external electrode 5 are formed on both end portions of the element body 2 by, for example, a dipping method. As described above, the coil component 1 is formed.

As described above, in the coil component 1 according to the present embodiment, the first connection conductor 8 has a shape that spreads outward over the entire circumference in the first end portion 8a. This increases the junction area between the first connection conductor 8 and the first external electrode 4. Therefore, the junction strength between the first connection conductor 8 and the first external electrode 4 can be improved. The second connection conductor 9 has a shape that spreads outward over the entire circumference in the first end portion 9a. This increases the junction area between the second connection conductor 9 and the second external electrode 5. Therefore, the junction strength between the second connection conductor 9 and the second external electrode 5 can be improved.

The first end portion 8a has a shape in which the cross section gradually increases toward the first external electrode 4. This increases the junction area between the first connection conductor 8 and the first external electrode 4. Therefore, the junction strength between the first connection conductor 8 and the first external electrode 4 can be improved. The first end portion 9a has a shape in which the cross section gradually increases toward the second external electrode 5. This increases the junction area between the second connection conductor 9 and the second external electrode 5. Therefore, the junction strength between the second connection conductor 9 and the second external electrode 5 can be improved.

The element body 2 includes the plurality of soft magnetic metal particles M.

The length L3 of the first end portion 8a in the first direction D1 is longer than the lengths L1 of the coil conductors 21 to 25 in the first direction D1. This increases the junction area between the first connection conductor 8 and the first external electrode 4. Therefore, the junction strength between the first connection conductor 8 and the first external electrode 4 can be improved. In addition, two or more soft magnetic metal particles M are arranged between the first connection conductor 8 and the coil conductor 21 along the first direction D1. As a result, the interlayer withstand voltage between the first connection conductor 8 and the coil conductor 21 can be improved. The length L6 of the first end portion 9a in the first direction D1 is longer than the length L1. This increases the junction area between the second connection conductor 9 and the second external electrode 5. Therefore, the junction strength between the second connection conductor 9 and the second external electrode 5 can be improved. Also, two or more soft magnetic metal particles M are arranged between the second connection conductor 9 and the coil conductor 25 along the first direction D1. As a result, withstand voltage between the second connection conductor 9 and a coil conductor 26 layers can be improved.

When viewed from the first direction D1, the line width W2 of the first end portion 8a is greater than the line widths W1 of coil conductors 21 to 25. Therefore, the junction area between the first connection conductor 8 and the first external electrode 4 are reliably increased. Therefore, the junction strength between the first connection conductor 8 and the first external electrode 4 can be reliably improved. When viewed from the first direction D1, the line width W3 of the first end portion 9a is greater than the line widths W1 of coil conductors 21 to 25. Therefore, the junction area between the second connection conductor 9 and the second external electrode 5 are reliably increased. Therefore, the junction strength between the second connection conductor 9 and the second external electrode 5 can be reliably improved.

The first external electrode 4 and the second external electrode 5 are conductive resin layers. Therefore, the densities of metal particles in the first external electrode 4 and the second external electrode 5 are lower than those in a configuration in which the first external electrode 4 and the second external electrode 5 are sintered metal layers. Therefore, the stray capacitance between the first external electrode 4 and the second external electrode 5 and the coil conductors 21 to 25 can be suppressed.

The length L4 of the first end portion 8a is half or less of the separation distance L5 between the coil conductor 21 and the first external electrode 4. Thus, the withstand voltage between the first end portion 8a and the coil conductor 21 can be secured. The length L7 of the first end portion 9a is half or less of the separation distance L8 between the coil conductor 25 and the second external electrode 5. Thus, the withstand voltage between the first end portion 9a and the coil conductor 25 can be secured.

The outer surface 8d of the first end portion 8a is curved so as to be recessed inward of the first connection conductor 8 in a cross section orthogonal to the end surface 2a. For this reason, it is easy to secure the withstand voltage between the first end portion 8a and the coil conductor 21. The outer surface of the first end portion 9a is curved so as to be recessed inward of the second connection conductor 9 in a cross section orthogonal to the end surface 2b. For this reason, it is easy to secure the withstand voltage between the first end portion 9a and the coil conductor 25.

The separation distance between adjacent coil conductors 21 to 25 is equal to the length L2. The separation distance L5 between the first external electrode 4 and the coil conductors 21 to 25 is longer than the length L2. The voltage between the coil conductors 22 to 25 and the first external electrode 4 is greater than the voltage between adjacent coil conductors 21 to 25. Since the separation distance L5 is longer than the length L2, the withstand voltage of the coil 3 is easily secured. The separation distance L8 between the second external electrode 5 and the conductors 21 to 25 is longer than the length L2. The voltage applied between the coil conductors 21 to 24 and the second external electrode 5 is greater than the voltage applied between adjacent coil conductors 21 to 25. Since the separation distance L8 is longer than the length L2, the withstand voltage of the coil 3 is easily secured.

The first connection conductor 8 and the second connection conductor 9 may be plated conductors. In the case of the plated conductors, the densities of the first connection conductor 8 and the second connection conductor 9 can be increased as compared with the case where the first connection conductor 8 and the second connection conductor 9 are sintered metal conductors. Therefore, the junction area between the first connection conductor 8 and the first external electrode 4 can be further increased. In addition, the junction area between the second connection conductor 9 and the second external electrode 5 can be further increased. The coil conductors 21 to 25 may also be plated conductors. In the case of the plated conductors, for example, the density of the conductor can be increased, and the electrical resistivity of the conductor can be decreased. Thus, the characteristics of the coil 3 can be improved.

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 can be made without departing from the scope of the present invention.

The element body 2 does not necessarily include soft magnetic metal particles, and may be made of ferrite (for example, Ni—Cu—Zn ferrite, Ni—Cu—Zn—Mg ferrite, or Cu—Zn ferrite), a dielectric material, or the like. The coil conductors 21 to 25, the through-hole conductors 31 to 36, the first connection conductor 8, the second connection conductor 9, the first electrode part 6, and the second electrode part 7 may be sintered metal conductors.

The second end portion 8b of the first connection conductor 8, the second end portion 9b of the second connection conductor 9, and the end portions 21a to 25a and 21b to 25b of the coil conductors 21 to 25 are enlarged when viewed from the first direction D1, but may not be enlarged. In this case, the first connection conductor 8, the second connection conductor 9, and coil conductors 21 to 25 are formed with the line width W1 up to each end portion.

The first connection conductor 8 and the coil conductor 21 are disposed on the element body layers different from each other, but may be disposed on the same element body layer. In this case, the first connection conductor 8 and the coil conductor 21 are directly connected so as to be continuous within the same element body layer without the through-hole conductor 31. The second connection conductor 9 and the coil conductor 25 are disposed on the element body layers different from each other, but may be disposed on the same element body layer. In this case, the second connection conductor 9 and the coil conductor 25 are directly connected so as to be continuous within the same element body layer without the through-hole conductor 36.

While the first connection conductor 8 is exposed to the end surface 2a and the second connection conductor 9 is exposed to the end surface 2b, the first connection conductor 8 and the second connection conductor 9 may be exposed to the main surface 2d. In this case, the first external electrode 4 and the second external electrode 5 may be bottom electrodes provided on the main surface 2d. Also, the laminating direction of the element body layers may be the second direction D2 or the third direction D3.

The first end portion 8a and the first end portion 9a may have different shapes from each other. At least one of the first end portion 8a and the first end portion 9a may have a shape expanding outward over the entire circumference toward the first external electrode 4 and the second external electrode 5.

COIL COMPONENT

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