Coil device

Abstract

The invention provides a coil device which can easily ensure installation strength and prevent short circuit between a lead-out part and a winding part. The coil device includes a magnetic material, and includes: a magnetic core having a mounting surface and a third side surface extending in a direction perpendicular to the mounting surface; and a lead wire having a winding portion disposed inside the magnetic core and a lead-out portion led out from the winding portion. The lead-out portion has a base end portion continuous with the winding portion, and a flat portion continuous with the base end portion and flattened into a flat shape. The flat portion has an embedded portion disposed inside the magnetic core, and a terminal portion having a plating layer and disposed outside the magnetic core. The embedded portion extends obliquely from the base end portion toward the third side surface. The terminal portion is exposed from the magnetic core at a central portion of the third side surface in a direction perpendicular to the mounting surface, and extends from the central portion of the third side surface toward the mounting surface.

Description

Technical Field

[0001] The present disclosure relates to a coil device. Background Art

[0002] For example, Patent Document 1 discloses a coil device that can be used as an inductor. The coil device of Patent Document 1 has a winding portion disposed inside a magnetic core and a lead-out portion led out from the winding portion. The lead-out portion has a flattened portion flattened into a flat shape and is led out from the side surface of the winding portion toward the magnetic core. A part of the flattened portion is disposed inside the magnetic core. The remaining part of the flattened portion protrudes from the magnetic core and extends along the side surface and the mounting surface of the magnetic core.

[0003] In the coil device of Patent Document 1, the flattened portion disposed on the mounting surface can be connected to the mounting substrate using a conductive bonding material (such as solder or a conductive adhesive). Thus, the flattened portion functions as a terminal of the coil device. Therefore, it is not necessary to additionally provide a terminal on the coil device, and miniaturization of the coil device and reduction in the number of components can be achieved.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2009-123927 Summary of the Invention

[0007] Technical Problem to be Solved by the Invention

[0008] However, in the coil device of Patent Document 1, the flattened portion is led out along the outer peripheral surface of the winding portion in a manner that is locally adjacent to the winding portion inside the magnetic core. Therefore, when the distance between the flattened portion and the winding portion becomes short due to miniaturization of the coil device, a short-circuit defect may occur between the flattened portion and the winding portion. In addition, in the coil device of Patent Document 1, since the area of the flattened portion disposed on the side surface of the magnetic core is small, it is difficult to form a fillet of solder or the like on the flattened portion disposed on the side surface of the magnetic core. Therefore, there is a problem that it is difficult to ensure the mounting strength of the coil device.

[0009] The present disclosure provides a coil device that can easily ensure the mounting strength and prevent a short-circuit defect from occurring between the lead-out portion and the winding portion.

[0010] Means for Solving the Technical Problem

[0011] The coil device of the present disclosure includes:

[0012] a magnetic core including a magnetic material, having a mounting surface and a side surface extending in a direction perpendicular to the mounting surface; and

[0013] A wire having a winding portion disposed inside the magnetic core and a lead portion extending from the winding portion.

[0014] The lead portion has a base end portion continuous with the winding portion and a flat portion continuous with the base end portion and flattened into a flat shape.

[0015] The flat portion has an embedded portion disposed inside the magnetic core and a terminal portion having a plating layer and disposed outside the magnetic core.

[0016] The embedded portion extends obliquely from the base end portion toward the side surface.

[0017] The terminal portion is exposed from the magnetic core at the central portion of the side surface in a direction perpendicular to the mounting surface and extends from the central portion of the side surface toward the mounting surface.

[0018] Alternatively, the embedded portion may extend from the base end portion to the central portion of the winding portion in a direction perpendicular to the mounting surface.

[0019] Alternatively, the embedded portion may extend obliquely from the base end portion to the side surface without being bent at a right angle.

[0020] Alternatively, the base end portion may have an inclined portion, and in a cross-section perpendicular to the mounting surface and the side surface, the thickness of the inclined portion becomes thinner as it approaches the flat portion.

[0021] Alternatively, the lead portion may bend at the boundary portion between the base end portion and the flat portion, and the radius of curvature of the lead portion at the boundary portion is greater than the thickness of the flat portion.

[0022] Alternatively, the wire may be a round wire or an edgewise-wound flat wire, and the winding portion has an insulating coating layer.

[0023] Alternatively, when viewed from a direction perpendicular to the mounting surface, the shape of the outer peripheral surface of the winding portion is circular.

[0024] Alternatively, the winding axis direction of the winding portion may be inclined with respect to the direction perpendicular to the mounting surface. Description of the Drawings

[0025] Figure 1A is a perspective view of the coil device of the first embodiment.

[0026] Figure 1B is a representation of Figure 1A a perspective view of the internal structure of the coil device.

[0027] Figure 2 is Figure 1B a perspective view of the wire shown.

[0028] Figure 3 is Figure 1B The top view of the coil device shown in the figure.

[0029] Figure 4A is along Figure 3 The sectional view taken along the line IVA-IVA shown in the figure.

[0030] Figure 4B is Figure 4A The sectional view of a modified example of the lead-out portion shown in the figure.

[0031] Figure 5A represents Figure 1A The top view of the manufacturing method of the coil device shown in the figure.

[0032] Figure 5B represents Figure 5A The top view of the subsequent process of the process shown in the figure.

[0033] Figure 5C represents Figure 5B The top view of the subsequent process of the process shown in the figure.

[0034] Figure 5D represents Figure 5C The top view of the subsequent process of the process shown in the figure.

[0035] Figure 5E represents Figure 5D The top view of the subsequent process of the process shown in the figure.

[0036] Figure 6A The sectional view of the coil device of the second embodiment.

[0037] Figure 6B is Figure 4A or Figure 6A The sectional view of a modified example of the winding portion shown in the figure.

[0038] Explanation of reference numerals

[0039] 1, 1A... Coil device

[0040] 10... Magnetic core

[0041] 11... First side

[0042] 12... Second side

[0043] 13... Third side

[0044] 14... Fourth side

[0045] 15... Mounting surface

[0046] 16... Opposite mounting surface

[0047] 17a, 17b... the first recess

[0048] 18a, 18b... the second recess

[0049] 19... the chamfered portion

[0050] 20, 20A... the lead

[0051] 21, 21A... the winding portion

[0052] 210a... the top surface

[0053] 210b... the bottom surface

[0054] 22a, 22b... the lead-out portion

[0055] 23... the base end portion

[0056] 230... the inclined portion

[0057] 231a, 231b... the inclined surface

[0058] 232... the non-inclined portion

[0059] 24... the flat portion

[0060] 240... the buried portion

[0061] 242... the terminal portion

[0062] 244... the side portion

[0063] 246... the mounting portion

[0064] 25... the inner surface

[0065] 26... the outer surface

[0066] 27a, 27b, 22a1, 22b1... the boundary portion

[0067] 30... the coating Detailed implementation manners

[0068] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In addition, the content shown in the drawings is only schematically and exemplarily shown for understanding the present disclosure, and the appearance, dimensional ratios, etc. may be different from the actual object. In addition, the present disclosure is not limited to the following embodiments.

[0069] (First Embodiment)

[0070] Figure 1A The shown coil device 1 is a surface-mounted inductor, for example, mounted on the power supply circuit of an electronic device. The coil device 1 has a magnetic core 10 and a lead 20(Figure 1B )。The shape of the magnetic core 10 is not particularly limited. In the Figure 1A example shown, it is actually a hexahedron. The shape of the magnetic core 10 can also be a cylinder, an elliptical cylinder, an n-sided polyhedron (n≥7), or other polygons. The magnetic core 10 has a first side 11, a second side 12, a third side 13, a fourth side 14, a mounting surface 15, and a mounting opposite surface 16.

[0071] The edge portion between the second side 12 and the third side 13 is chamfered, and a chamfered portion 19 is formed at the edge portion between the second side 12 and the third side 13. By forming the chamfered portion 19 on the magnetic core 10, the orientation of the magnetic core 10 can be easily identified. However, the chamfered portion 19 is not essential and can be omitted.

[0072] The first side 11 and the second side 12 face each other. The third side 13 and the fourth side 14 face each other. The mounting surface 15 and the mounting opposite surface 16 face each other.

[0073] In Figure 1A etc., the X-axis is the axis along the direction in which the first side 11 and the second side 12 face each other. The Y-axis is the axis along the direction in which the third side 13 and the fourth side 14 face each other. The Z-axis is the axis along the direction in which the mounting surface 15 and the mounting opposite surface 16 face each other (the direction perpendicular to the mounting surface 15).

[0074] The X-axis, Y-axis, and Z-axis are perpendicular to each other. Hereinafter, for each of the X-axis, Y-axis, and Z-axis, the direction away from the center of the magnetic core 10 is defined as "outer side", and the direction approaching the center of the magnetic core 10 is defined as "inner side". In addition, the positive direction side of the Z-axis is defined as "upper side", and the negative direction side of the Z-axis is defined as "lower side". However, the upper side in the Z-axis direction does not necessarily coincide with the upper side in the vertical direction. In addition, the lower side in the Z-axis direction does not necessarily coincide with the lower side in the vertical direction.

[0075] The width of the magnetic core 10 in the X-axis direction is not particularly limited, for example, it is 3.0 to 10.0 mm. The width of the magnetic core 10 in the Y-axis direction is not particularly limited, for example, it is 3.0 to 10.0 mm. The width of the magnetic core 10 in the Z-axis direction (the thickness of the magnetic core 10) is not particularly limited, and it is 2.0 to 10.0 mm.

[0076] The magnetic core 10 is composed of a composite material containing a magnetic material and a resin. The method of forming the magnetic core 10 is not particularly limited, for example, it is powder pressing, injection molding, or machining. In the present embodiment, the magnetic core 10 is a powder compact containing a magnetic material and a resin. The magnetic material constituting the magnetic core 10 is not particularly limited, for example, it is ferrite (Ni-Zn based ferrite, Mn-Zn based ferrite, etc.) or a metal magnetic material. The resin constituting the magnetic core 10 is not particularly limited, for example, it is an epoxy resin or a phenolic resin.

[0077] The magnetic core 10 has first recesses 17a and 17b and second recesses 18a and 18b. The first recesses 17a and the second recesses 18a are continuously formed from the third side surface 13 to the mounting surface 15. The first recesses 17b and the second recesses 18b are continuously formed from the fourth side surface 14 to the mounting surface 15.

[0078] The first recess 17a is formed on the third side surface 13, and the first recess 17b is formed on the fourth side surface 14. The side portion 244 of the lead portion 22a described later is disposed in the first recess 17a, and the side portion 244 of the lead portion 22b described later is disposed in the first recess 17b. The width of the first recess 17a or 17b in the X-axis direction is wider than the width of the side portion 244 in the X-axis direction.

[0079] The second recesses 18a and 18b are formed on the mounting surface 15. The mounting portion 246 of the lead portion 22a described later is disposed in the second recess 18a, and the mounting portion 246 of the lead portion 22b described later is disposed in the second recess 18b. The width of the second recess 18a or 18b in the X-axis direction is wider than the width of the mounting portion 246 in the X-axis direction. The depth of the second recess 18a or 18b is equal to or less than the thickness of the mounting portion 246. The first recesses 17a and 17b and the second recesses 18a and 18b are not essential and may be omitted from the magnetic core 10.

[0080] As Figure 1B shown, the wire 20 has a winding portion 21, a lead portion 22a, and a lead portion 22b. The wire 20 is, for example, an insulated coated wire in which a conductive core wire is coated with an insulating film (insulating coating layer). As the wire 20, for example, known windings such as AIW (polyamideimide copper wire), UEW (polyurethane copper wire), and PEW (polyester copper wire) can be used. The material constituting the wire is not particularly limited and is, for example, copper, copper alloy, silver, or nickel. The wire 20 is a round wire, but may also be a flat wire (for example, a flat wire wound flatly), etc. The diameter of the wire 20 is not particularly limited and is, for example, 0.3 to 2.0 mm.

[0081] The winding portion 21 is an air-core coil and is disposed inside the magnetic core 10. As Figure 2 shown, the wire 20 is wound in a spiral shape with 2.5 turns in the winding portion 21. The winding axis direction of the winding portion 21 corresponds to the Z-axis direction. The number of layers in the winding axis direction (Z-axis direction) of the winding portion 21 is 3 layers (refer to Figure 4A)。However, the number of turns of the wire 20 is not particularly limited and may be 1.5 turns or 3.5 turns or more. In addition, the number of layers in the winding direction of the winding portion 21 may be 2 layers or 4 layers or more. In the winding portion 21, an insulating film (insulating coating layer) is formed on the surface of the wire 20. When viewed from a direction (Z-axis direction) perpendicular to the mounting surface 15, the shape of the outer peripheral surface of the winding portion 21 is circular, but it may also be elliptical or the like.

[0082] The lead-out portion 22a is led out from the third layer in the winding direction of the winding portion 21. The lead-out portion 22b is led out from the first layer in the winding direction of the winding portion 21 toward the side opposite to the lead-out portion 22a. The lead-out portions 22a and 22b each have a base end portion 23 and a flat portion 24. As Figure 4A shown, the lead-out portion 22a has an inner surface 25 facing the mounting surface 15 or the inner surface of the third side surface 13 and an outer surface 26 opposite to the inner surface 25. In addition, the lead-out portion 22b has an inner surface 25 facing the mounting surface 15 or the inner surface of the fourth side surface 14 and an outer surface 26 opposite to the inner surface 25.

[0083] The base end portion 23 and the flat portion 24 are formed by flattening (stamping or extrusion) the lead-out portion 22a or 22b. The flat portion 24 is the portion where the lead-out portion 22a or 22b is flattened into a flat shape. On the other hand, the base end portion 23 is the portion where the thickness (the thickness between the inner surface 25 and the outer surface 26) of the lead-out portion 22a or 22b gradually becomes thinner as it goes from the winding portion 21 toward the flat portion 24. In other words, unlike the flat portion 24, the base end portion 23 is the portion where the lead-out portion 22a or 22b is not completely flattened. Hereinafter, the details of the base end portion 23 and the flat portion 24 will be described.

[0084] The base end portion 23 has a front tapered shape that tapers from the winding portion 21 toward the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10. The base end portion 23 is disposed inside the magnetic core 10. One end in the extending direction of the base end portion 23 is continuous with the winding portion 21, and the other end in the extending direction of the base end portion 23 is continuous with the flat portion 24. The base end portion 23 of the lead-out portion 22a is located above the center of the magnetic core 10 in the Z-axis direction. In addition, the base end portion 23 of the lead-out portion 22b is located below the center of the magnetic core 10 in the Z-axis direction.

[0085] The base end portion 23 has an inclined portion 230. The inclined portion 230 is disposed inside the magnetic core 10. In a cross section (i.e., YZ cross section) perpendicular to the mounting surface 15 and the third side surface 13, the thickness (the thickness between the inner surface 25 and the outer surface 26) of the inclined portion 230 becomes thinner as it approaches the boundary portion 27a between the base end portion 23 and the flat portion 24. The boundary portion 27a between the base end portion 23 and the flat portion 24 is disposed inside the magnetic core 10 and does not protrude from the magnetic core 10.

[0086] AsFigure 3 As shown, when viewed from a direction perpendicular to the mounting surface 15 (i.e., the Z-axis direction), the width of the inclined portion 230 in the X-axis direction becomes wider as it approaches the boundary portion 27a between the base end portion 23 (inclined portion 230) and the flat portion 24 ( Figure 4A ).

[0087] As Figure 4A shown, an inclined surface 231a is formed on the inner surface 25 of the inclined portion 230. The inclined surface 231a inclines toward the side opposite to the mounting surface 15 (the mounting opposite surface 16 side or above) as it approaches the boundary portion 27a between the base end portion 23 and the flat portion 24. At the center of the inclined surface 231a in the Y-axis direction, the inclination angle of the inclined surface 231a with respect to the mounting surface 15 is not particularly limited, for example, it is 10° or more and less than 90° or 30° or more and less than 90°. The inclined surface 231a is a curved surface, but it can also be a flat surface.

[0088] An inclined surface 231b is formed on the outer surface 26 of the inclined portion 230. The inclined surface 231b inclines toward the mounting surface 15 side (downward) as it approaches the boundary portion 27a between the base end portion 23 and the flat portion 24. At the center of the inclined surface 231b in the Y-axis direction, the inclination angle of the inclined surface 231b with respect to the mounting opposite surface 16 is not particularly limited, for example, it is 10° or more and less than 90° or 30° or more and less than 90°. The inclined surface 231b is a curved surface, but it can also be a flat surface.

[0089] At the base end portion 23 (inclined portion 230), the coating film of the wire 20 is not peeled off, and the surface of the base end portion 23 (inclined portion 230) is covered with the coating film. However, the coating film of the wire 20 can also be peeled off at at least a part of the base end portion 23 (inclined portion 230).

[0090] Although detailed illustrations are omitted, the inclined portion 230 can also have the inclined surface 231a, and on the other hand, does not have the inclined surface 231b. Or, the inclined portion 230 can also have the inclined surface 231b, and on the other hand, does not have the inclined surface 231a.

[0091] As Figure 4B shown, in addition to the inclined portion 230, the base end portion 23 can also have a non-inclined portion 232. The non-inclined portion 232 is located between the winding portion 21 and the inclined portion 230. Different from the inclined portion 230, the non-inclined portion 232 is a portion where the lead-out portion 22a or 22b is not flattened. Therefore, the diameter of the wire 20 in the non-inclined portion 232 is equal to the diameter of the wire 20 in the winding portion 21.

[0092] As Figure 4A shown, the flat portion 24 is continuous with the base end portion 23 and is flattened into a flat shape. As Figure 2As shown, the flat portion 24 has a flat shape and is formed to be wider than the diameter Φ of the wire 20 in the X-axis direction. Figure 2 The width W in the X-axis direction of the flat portion 24 shown is not particularly limited and is, for example, 1 to 10 mm. The ratio W / Φ of the width W in the X-axis direction of the flat portion 24 to the diameter (where the diameter of the wire 20 in the winding portion 21) Φ of the wire 20 is not particularly limited and is, for example, 1 < W / Φ ≤ 10, or 2 ≤ W / Φ ≤ 8.

[0093] The thickness of the flat portion 24 is not particularly limited and is, for example, 0.05 to 0.5 mm. The ratio T / Φ of the thickness T of the flat portion 24 to the diameter (where the diameter of the wire 20 in the winding portion 21) Φ of the wire 20 is not particularly limited and is, for example, 1 / 15 ≤ T / Φ ≤ 1 / 2, or 1 / 10 ≤ T / Φ ≤ 1 / 3.

[0094] The thickness (the thickness between the inner surface 25 and the outer surface 26) of the flat portion 24 is substantially constant along the extending direction of the flat portion 24. However, "substantially constant" means that the error of the thickness of the flat portion 24 is within several % to several tens % (not particularly limited, for example, ±10%, or ±5%, or ±3%).

[0095] As Figure 4A shown, the lead-out portion 22a or 22b buckles at the boundary portion 27a between the base end portion 23 and the flat portion 24. At the boundary portion 27a between the base end portion 23 and the flat portion 24, the radius of curvature of the lead-out portion 22a is not particularly limited but is larger than the thickness of the flat portion 24. In addition, at the boundary portion 27a between the base end portion 23 and the flat portion 24, the radius of curvature of the lead-out portion 22b is not particularly limited but is larger than the thickness of the flat portion 24. However, in Figure 4A the flat portion 24 has a relatively large thickness shown, so that at the boundary portion 27a, the radius of curvature of the lead-out portion 22a or 22b is shown to be smaller than the thickness of the flat portion 24. At the boundary portion 27a, the radius of curvature of the lead-out portion 22a or 22b may be equal to the thickness of the flat portion 24 or may also be smaller than the thickness of the flat portion 24.

[0096] The flat portion 24 has a buried portion 240 and a terminal portion 242. The buried portion 240 is disposed inside the magnetic core 10. In the buried portion 240, the coating film of the wire 20 is not peeled off, and the surface of the buried portion 240 is covered with the coating film of the wire 20. The buried portion 240 extends obliquely from the base end portion 23 toward the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10 in a manner buckled with respect to the base end portion 23. In Figure 4A the example shown, the entire region along the extending direction of the buried portion 240 is inclined with respect to the side surface of the magnetic core 10, but a part of the buried portion 240 along the extending direction may also be inclined with respect to the side surface of the magnetic core 10.

[0097] The extending direction of the buried portion 240 is inclined with respect to the direction (Z-axis direction) perpendicular to the mounting surface 15. Further, the extending direction of the buried portion 240 is inclined with respect to the winding axis direction (Z-axis direction) of the winding portion 21. Further, the extending direction of the buried portion 240 is inclined with respect to the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10. Further, the extending direction of the buried portion 240 is inclined with respect to the mounting surface 15 and the mounting opposite surface 16.

[0098] Around the boundary portion 27a between the base end portion 23 and the flat portion 24, the inclination angle of the buried portion 240 with respect to the winding axis direction (Z-axis direction) of the winding portion 21 or the direction (Z-axis direction) perpendicular to the mounting surface 15 is not particularly limited, and is, for example, 5° or more and less than 90°, 10° or more and less than 80°, or 20° or more and less than 70°. The above inclination angle is the same around the boundary portion 27b between the buried portion 240 and the terminal portion 242. Further, the above inclination angle is the same at the central portion in the extending direction of the buried portion 240.

[0099] Around the boundary portion 27a between the base end portion 23 and the flat portion 24, the inclination angle of the buried portion 240 with respect to the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10 is not particularly limited, and is, for example, 5° or more and less than 90°, 10° or more and less than 80°, or 20° or more and less than 70°. The above inclination angle is the same around the boundary portion 27b between the buried portion 240 and the terminal portion 242. Further, the above inclination angle is the same at the central portion in the extending direction of the buried portion 240.

[0100] The buried portion 240 linearly extends from the base end portion 23 toward the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10. However, the buried portion 240 may also extend while buckling or bending in a manner not bent at a right angle from the base end portion 23 toward the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10. However, in the present embodiment, "right angle" is not limited to a strict right angle (i.e., 90°), and a state deviated from the strict right angle by several degrees (not particularly limited, for example, 3 degrees) or less is also included in the concept of "right angle".

[0101] For example, the buried portion 240 may also buckle or bend from the base end portion 23 toward the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10 in a manner convex toward the mounting surface 15 as a whole. Or, the buried portion 240 may also buckle or bend from the base end portion 23 toward the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10 in a manner convex toward the mounting opposite surface 16 as a whole. Or, the buried portion 240 may also buckle or bend from the base end portion 23 toward the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10 in a wavy manner.

[0102] The inclination angle of the buried portion 240 of the lead-out portion 22a with respect to the reel direction (Z-axis direction) of the winding portion 21 or the direction (Z-axis direction) perpendicular to the mounting surface 15 is substantially equal to the inclination angle of the buried portion 240 of the lead-out portion 22b with respect to the reel direction (Z-axis direction) of the winding portion 21 or the direction (Z-axis direction) perpendicular to the mounting surface 15. However, "substantially equal" is defined as a concept that includes not only the case where the inclination angle of the former is exactly the same as the inclination angle of the latter, but also the case where the inclination angle of the former differs from the inclination angle of the latter by within ±3°. The inclination angle of the former can be smaller than the inclination angle of the latter, or can also be larger than the inclination angle of the latter.

[0103] The buried portion 240 of the lead-out portion 22a extends in a descending manner from the base end portion 23 toward the central portion in the Z-axis direction of the third side surface 13. The buried portion 240 of the lead-out portion 22b extends in an ascending manner from the base end portion 23 toward the central portion in the Z-axis direction of the fourth side surface 14. However, the central portion in the Z-axis direction of the third side surface 13 or the fourth side surface 14 is not limited to the strict center in the Z-axis direction of the third side surface 13 or the fourth side surface 14, but also includes positions at a prescribed length above and below the strict center in the Z-axis direction. Here, the prescribed length is not particularly limited. For example, it is a length equivalent to Figure 4A 10% or less, 8% or less, 5% or less, or 3% or less of the height H of the magnetic core 10 shown.

[0104] In the direction perpendicular to the mounting surface 15 (Z-axis direction), the buried portion 240 extends from the base end portion 23 to the central portion of the winding portion 21. Here, the central portion in the Z-axis direction of the winding portion 21 is not limited to the strict center in the Z-axis direction of the winding portion 21, but also includes positions at a prescribed length above and below the strict center in the Z-axis direction. Here, the prescribed length is not particularly limited. For example, it is a length equivalent to 10% or less, 8% or less, 5% or less, or 3% or less of the height of the winding portion 21 along the reel direction. In Figure 4A the example shown, in the direction perpendicular to the mounting surface 15 (Z-axis direction), the buried portion 240 extends from the base end portion 23 of the first layer or the third layer of the winding portion 21 to the second layer of the winding portion 21.

[0105] In the present embodiment, the central portion in the Z-axis direction of the winding portion 21 is located at the central portion in the Z-axis direction of the magnetic core 10. However, the central portion in the Z-axis direction of the winding portion 21 can be located above the central portion in the Z-axis direction of the magnetic core 10, or can also be located below the central portion in the Z-axis direction of the magnetic core 10.

[0106] The terminal portion 242 is continuous with the buried portion 240 and is disposed outside the magnetic core 10. The terminal portion 242 extends along the side surface (the third side surface 13 or the fourth side surface 14) and the mounting surface 15 of the magnetic core 10. In the terminal portion 242, the coating film of the wire 20 is peeled off, and the surface of the terminal portion 242 is not covered by the coating film of the wire 20. Around the boundary portion 27b between the buried portion 240 and the terminal portion 242, the terminal portion 242 faces the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10 and is bent with respect to the buried portion 240. The boundary portion 27b between the buried portion 240 and the terminal portion 242 is not disposed inside the magnetic core 10 and is exposed from the magnetic core 10.

[0107] The flat portion 24 buckles at the boundary portion 27b between the buried portion 240 and the terminal portion 242. At the boundary portion 27b between the buried portion 240 and the terminal portion 242, the radius of curvature of the flat portion 24 is not particularly limited, but is larger than the thickness of the flat portion 24. However, at the boundary portion 27b between the buried portion 240 and the terminal portion 242, the radius of curvature of the flat portion 24 may be equal to the thickness of the flat portion 24, or may be smaller than the thickness of the flat portion 24.

[0108] The terminal portion 242 has a side portion 244 and a mounting portion 246. The side portion 244 is continuous with the buried portion 240 and is bent with respect to the buried portion 240. The side portion 244 is exposed from the magnetic core 10 at the central portion of the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10 in the direction (Z-axis direction) perpendicular to the mounting surface 15. Moreover, the side portion 244 extends along the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10 from the central portion of the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10 toward the mounting surface 15.

[0109] The side portion 244 is disposed parallel to the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10. In the present embodiment, "parallel" is not limited to strict parallelism, and a state deviated from strict parallelism by several degrees (not particularly limited, for example, 3 degrees) or less is also included in the concept of "parallel". In addition, "perpendicular" is not limited to strict perpendicularity, and a state deviated from strict perpendicularity by several degrees (not particularly limited, for example, 3 degrees) or less is also included in the concept of "perpendicular".

[0110] The side portion 244 abuts against the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10. However, the side portion 244 may not abut against the side surface of the magnetic core 10, or a gap may be formed between the side portion 244 and the side surface of the magnetic core 10. In Figure 4A the example shown, the entire side portion 244 abuts against the side surface of the magnetic core 10, but a part of the side portion 244 may also abut against the side surface of the magnetic core 10.

[0111] The length of the side portion 244 along the Z axis is approximately equal to 1 / 2 of the height H of the magnetic core 10. However, "approximately equal" is defined as a concept that includes not only the case where the length of the side portion 244 along the Z axis is exactly the same as 1 / 2 of the height H of the magnetic core 10, but also the case where the length of the side portion 244 along the Z axis differs from 1 / 2 of the height H of the magnetic core 10 by within ±5%.

[0112] The side portion 244 extends obliquely with respect to the buried portion 240. In addition, the side portion 244 extends linearly from the boundary portion 27b between the buried portion 240 and the terminal portion 242 toward the mounting surface 15. However, the side portion 244 may also extend from the boundary portion 27b between the buried portion 240 and the terminal portion 242 toward the mounting surface 15 while buckling or bending.

[0113] The mounting portion 246 is continuous with the side portion 244 and extends in a direction orthogonal to the side portion 244. The mounting portion 246 extends along the mounting surface 15. The mounting portion 246 is a portion connected to a mounting substrate (not shown) using a conductive bonding material (such as solder and conductive adhesive).

[0114] As Figure 1A shown, the mounting portion 246 of the lead-out portion 22a is disposed in the second recess 18a formed on the mounting surface 15. In addition, the mounting portion 246 of the lead-out portion 22b is disposed in the second recess 18b formed on the mounting surface 15. In addition, the side portion 244 of the lead-out portion 22a is disposed in the first recess 17a formed on the third side surface 13. In addition, the side portion 244 of the lead-out portion 22b is disposed in the first recess 17b formed on the fourth side surface 14.

[0115] As Figure 4A shown, a plating layer 30 is formed on the inner surface 25 and the outer surface 26 of the lead-out portion 22a. In addition, a plating layer 30 is formed on the inner surface 25 and the outer surface 26 of the lead-out portion 22b. The plating layer 30 is formed on the terminal portion 242, which is the portion of the lead-out portion 22a or 22b that is exposed from the magnetic core 10. By forming the plating layer 30 on the outer surface 26 of the terminal portion 242, the adhesion of the bonding material (such as solder or conductive adhesive) to the outer surface 26 is improved during the installation of the coil device 1. The plating layer 30 may be a single layer or may also be a multi-layer. The plating layer 30 is not particularly limited, and examples include Cu plating, Ni plating, Sn plating, Ni-Sn plating, Cu-Ni-Sn plating, Ni-Au plating, Au plating, and Sn-Pb plating (solder plating).

[0116] A plating layer 30 is formed on either the inner surface 25 or the outer surface 26 of the terminal portion 242. However, the plating layer 30 may not be formed on the inner surface 25 of the terminal portion 242 (side portion 244 or mounting portion 246), or may be formed on the outer surface 26 of the terminal portion 242 (side portion 244 or mounting portion 246). In this case, the inner surface 25 of the terminal portion 242 (side portion 244 or mounting portion 246) may also be covered with the coating film of the wire 20.

[0117] The plating layer 30 is formed on any part of the side portion 244 and the mounting portion 246 of the terminal portion 242. However, the plating layer 30 may also be formed on the mounting portion 246, and on the other hand, may not be formed on the side portion 244. In this case, the side portion 244 may also be covered with the coating film of the wire 20.

[0118] In the flat portion 24, the buried portion 240 disposed inside the magnetic core 10 is not formed with the plating layer 30. In addition, the base end portion 23 disposed inside the magnetic core 10 is not formed with the plating layer 30. However, the plating layer 30 may also be formed on the inner surface 25 and / or the outer surface 26 of the buried portion 240. In addition, the plating layer 30 may also be formed on the inner surface 25 and / or the outer surface 26 of the base end portion 23.

[0119] Next, with reference to Figures 5A - 5E etc., Figure 1B The manufacturing method of the coil device 1 shown will be described. First, as Figure 5A shown, a wire 20 having a winding portion 21 and lead portions 22a and 22b led out from the winding portion 21 is prepared. The wire 20 is a round wire, but may also be a flat wire. The winding portion 21 is an air-core coil, and the lead portions 22a and 22b face opposite sides to each other and are led out from the winding portion 21.

[0120] Next, as Figure 5B shown, the lead portion 22a is flattened to form a flat portion 24 in a flat shape and an inclined portion 230 in an inclined shape on the lead portion 22a (refer to Figure 4A ). The inclined portion 230 has a thickness (the thickness between the inner surface 25 and the outer surface 26) that gradually thins as it goes from the winding portion 21 toward the flat portion 24. The range of flattening the lead portion 22a is, for example, the range from the boundary portion 22a1 between the winding portion 21 and the lead portion 22a to the front end portion 22a2 of the lead portion 22a. As a result, a base end portion 23 having the inclined portion 230 shown in Figure 4A is formed around the boundary portion 22a1 between the winding portion 21 and the lead portion 22a. In addition, a flat portion 24 is formed on the front end side of the lead portion 22a with respect to the base end portion 23.

[0121] In addition, as Figure 5B shown, the lead portion 22b is flattened to form a flat portion 24 in a flat shape and an inclined portion 230 in an inclined shape on the lead portion 22b (refer toFigure 4A )。 The inclined portion 230 has a thickness that gradually thins as it goes from the winding portion 21 toward the flat portion 24. The range where the flattened lead-out portion 22b is flattened is, for example, the range from the boundary portion 22b1 between the winding portion 21 and the lead-out portion 22b to the front end portion 22b2 of the lead-out portion 22b. Thus, a base end portion 23 of the inclined portion 230 as shown is formed around the periphery of the boundary portion 22b1 between the winding portion 21 and the lead-out portion 22b. In addition, a flat portion 24 is formed on the front end side of the lead-out portion 22b with respect to the base end portion 23. Figure 4A shown.

[0122] Next, as Figure 5C shown, the flat portion 24 of the lead-out portion 22a is bent at two places. First, at the boundary portion 27a between the base end portion 23 and the flat portion 24, the flat portion 24 extending horizontally (refer to Figure 5B ) is bent downward. Thus, as Figure 5C shown, the flat portion 24 extends obliquely downward with respect to the base end portion 23. In addition, for example, on the side of the flat portion 24 closer to the winding portion 21 than the center in the extending direction, the flat portion 24 (the portion shown by the dashed line in Figure 5C ) is bent upward (the orientation indicated by the arrow in Figure 5C ). More specifically, the flat portion 24 (the portion shown by the dashed line in Figure 5C ) is bent upward in such a manner that the bent portion is perpendicular to the winding axis direction of the winding portion 21. Thus, a buried portion 240 that is inclined with respect to the winding axis direction of the winding portion 21 and a terminal portion 242 that is orthogonal to the winding axis direction of the winding portion 21 are formed in the flat portion 24.

[0123] In addition, the flat portion 24 of the lead-out portion 22b is bent at two places. First, at the boundary portion 27a between the base end portion 23 and the flat portion 24, the flat portion 24 extending horizontally (refer to Figure 5B ) is bent upward. Thus, as Figure 5C shown, the flat portion 24 extends obliquely upward with respect to the base end portion 23. In addition, for example, on the side of the flat portion 24 closer to the winding portion 21 than the center in the extending direction, the flat portion 24 (the portion shown by the dashed line in Figure 5C ) is bent downward. More specifically, the flat portion 24 (the portion shown by the dashed line in Figure 5C ) is bent downward in such a manner that the bent portion is perpendicular to the winding axis direction of the winding portion 21. Thus, a buried portion 240 that is inclined with respect to the winding axis direction of the winding portion 21 and a terminal portion 242 that is orthogonal to the winding axis direction of the winding portion 21 are formed in the flat portion 24.

[0124] Next, it is set in the cavity of a mold (not shown) Figure 5CThe wire 20 shown fills the chamber with a core material containing a magnetic material and a resin. At this time, the winding portion 21 is buried in the core material, the buried portion 240 is buried in the core material, and the terminal portion 242 is exposed from the core material, and the core material is filled into the chamber. Then, during a specified time period, the core material filled into the chamber is compressed and cured at a specified mold temperature to form Figure 5D the core 10 shown.

[0125] Next, for example, a laser is irradiated on the terminal portion 242 exposed from the core 10 to peel the coating film on the surface of the terminal portion 242. Next, as Figure 5E shown, a plating layer 30 is formed on the terminal portion 242 exposed from the core 10. In the present embodiment, the plating layer 30 is formed on the inner surface 25 ( Figure 4A ) and the outer surface 26 ( Figure 4A ) of the terminal portion 242, but the plating layer 30 may be formed only on the outer surface 26 of the terminal portion 242. The plating layer 30 is not particularly limited, for example, it is Sn-Pb plating (solder plating). The method of forming the plating layer 30 is not particularly limited, for example, electroless plating, electroplating or dipping. In addition, the process of forming the plating layer 30 on the terminal portion 242 may also be performed before the forming of the core 10 ( Figure 5D shown process).

[0126] Next, as Figure 4A shown, around the boundary portion 27b between the buried portion 240 and the terminal portion 242, the terminal portion 242 of the lead-out portion 22a is bent with respect to the buried portion 240 toward the third side surface 13 of the core 10 (refer to Figure 4A the figure shown by the double-dot chain line). Thus, the side portion 244 of the terminal portion 242 is arranged along the third side surface 13. In addition, around the boundary portion 27b between the buried portion 240 and the terminal portion 242, the terminal portion 242 of the lead-out portion 22b is bent with respect to the buried portion 240 toward the fourth side surface 14 of the core 10. Thus, the side portion 244 of the terminal portion 242 is arranged along the fourth side surface 14.

[0127] Next, the front end portion of the terminal portion 242 arranged along the third side surface 13 is bent toward the mounting surface 15 of the core 10. Thus, the mounting portion 246 of the terminal portion 242 is arranged along the mounting surface 15. In addition, the front end portion of the terminal portion 242 arranged along the fourth side surface 14 is bent toward the mounting surface 15 of the core 10. Thus, the mounting portion 246 of the terminal portion 242 is arranged along the mounting surface 15. As described above, the coil device 1 can be manufactured.

[0128] As Figure 4AAs shown, in the coil device 1 of the present embodiment, the buried portion 240 extends obliquely from the base end portion 23 toward the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10. Therefore, as it approaches the side surface of the magnetic core 10 (or as it moves away from the base end portion 23), the buried portion 240 moves away from the winding portion 21, and the distance (the distance along the Y axis) between the buried portion 240 and the winding portion 21 becomes longer. Thereby, it is possible to prevent a short-circuit defect from occurring between the buried portion 240 and the winding portion 21.

[0129] In addition, the terminal portion 242 protrudes from the magnetic core 10 at the central portion of the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10 in the direction perpendicular to the mounting surface 15 (the Z-axis direction). Moreover, the terminal portion 242 extends from the central portion of the side surface of the magnetic core 10 toward the mounting surface 15. Therefore, it is easy to ensure the area of the terminal portion 242 (i.e., the side portion 244) disposed on the side surface of the magnetic core 10, and it is easy to form a solder fillet on the terminal portion 242 (side portion 244) disposed on the side surface of the magnetic core 10. Thereby, the mounting strength of the coil device 1 can be ensured.

[0130] In addition, when the terminal portion 242 protrudes from the magnetic core 10 at the central portion of the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10, compared with the case where the terminal portion 242 protrudes from the magnetic core 10 at the lower portion of the side surface of the magnetic core 10, it is easier to bend the terminal portion 242 relative to the buried portion 240 toward the side surface of the magnetic core 10. Thereby, it is possible to facilitate the manufacture of the coil device 1. In addition, when the terminal portion 242 protrudes from the magnetic core 10 at the central portion of the side surface of the magnetic core 10, compared with the case where the terminal portion 242 protrudes from the magnetic core 10 at the upper portion of the side surface of the magnetic core 10, the DC resistance of the coil device 1 can be reduced.

[0131] In addition, the buried portion 240 extends from the base end portion 23 to the central portion of the winding portion 21 in the direction perpendicular to the mounting surface 15 (the Z-axis direction). Therefore, the center of gravity of the wire 20 (winding portion 21) is stable. Thereby, in the manufacturing process of the coil device 1, for example, when the wire 20 is disposed in a mold and compression-molded, it is possible to prevent the displacement of the wire 20.

[0132] In addition, the buried portion 240 extends obliquely from the base end portion 23 to the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10 without being bent at a right angle. Therefore, the DC resistance of the coil device 1 can be reduced. In addition, damage to the buried portion 240 caused by bending can be prevented.

[0133] In addition, the base end portion 23 has an inclined portion 230. Moreover, in a cross-section (YZ cross-section) perpendicular to the mounting surface 15 and the third side surface 13, the thickness of the inclined portion 230 becomes thinner as it approaches the flat portion 24. By providing the inclined portion 230 at the base end portion 23, compared with the case where the inclined portion 230 is not provided at the base end portion 23 (that is, the case where the thickness of the base end portion 23 suddenly or abruptly thins at the boundary portion 27a between the base end portion 23 and the flat portion 24), the DC resistance of the coil device 1 can be reduced.

[0134] In addition, the lead-out portion 22a buckles at the boundary portion 27a between the base end portion 23 and the flat portion 24. Moreover, the radius of curvature of the lead-out portion 22a at the boundary portion 27a is larger than the thickness of the flat portion 24. Therefore, it is easy to lead out the buried portion 240 obliquely from the base end portion 23 toward the side surface of the magnetic core 10 so that the buried portion 240 moves away from the winding portion 21 as it approaches the side surface of the magnetic core 10 (the third side surface 13 or the fourth side surface 14) (or as it moves away from the base end portion 23). Therefore, it is easy to ensure the distance between the buried portion 240 and the winding portion 21, and it is possible to effectively prevent a short-circuit defect from occurring between the buried portion 240 and the winding portion 21.

[0135] In addition, the wire 20 is a round wire or a flat wire wound flat (in the present embodiment, it is a round wire), and the winding portion 21 has an insulating coating layer. Therefore, it is easy to flatten the lead-out portion 22a into a flat shape, and it is easy to form the flat portion 24 on the lead-out portion 22a. In addition, through the insulating coating layer, the winding portion 21 can be insulated from the magnetic material constituting the magnetic core 10.

[0136] In addition, when viewed from the direction (Z-axis direction) perpendicular to the mounting surface 15, the shape of the outer peripheral surface of the winding portion 21 is circular. Therefore, as Figure 1A shown, in the case where the magnetic core 10 has a first side surface 11 and a second side surface 12 opposite to each other in the X-axis direction, and a third side surface 13 and a fourth side surface 14 opposite to each other in the Y-axis direction, the following effects can be obtained. That is, in this case, as Figure 3As shown, when viewed from a direction perpendicular to the mounting surface 15, the distance in the X-axis direction between the outer peripheral surface of the winding portion 21 and the first side surface 11 is likely to be equal to the distance in the X-axis direction between the outer peripheral surface of the winding portion 21 and the second side surface 12. In addition, the distance in the Y-axis direction between the outer peripheral surface of the winding portion 21 and the third side surface 13 is likely to be equal to the distance in the Y-axis direction between the outer peripheral surface of the winding portion 21 and the fourth side surface 14. Therefore, the volume of the magnetic core 10 filled between the outer peripheral surface of the winding portion 21 and the first side surface 11 is likely to be equal to the volume of the magnetic core 10 filled between the outer peripheral surface of the winding portion 21 and the second side surface 12. In addition, the volume of the magnetic core 10 filled between the outer peripheral surface of the winding portion 21 and the third side surface 13 is likely to be equal to the volume of the magnetic core 10 filled between the outer peripheral surface of the winding portion 21 and the fourth side surface 14. Thereby, the inductance characteristics of the coil device 1 can be improved.

[0137] In addition, in the present embodiment, as Figure 5C shown, before the step ( Figure 5D ) of compression molding the magnetic core material, the flat portion 24 is formed into a shape in which an inclined buried portion 240 is formed in the flat portion 24. The wire 20 that has been subjected to such forming is disposed in a mold, and the magnetic core material is compression molded in the mold, whereby the displacement of the wire 20 during compression molding can be effectively prevented.

[0138] (Second Embodiment)

[0139] Figure 6A The coil device 1A of the second embodiment shown has the same structure as the coil device 1 of the first embodiment except for the points described below. The same reference numerals are assigned to the parts that are the same as those of the coil device 1 of the first embodiment, and the detailed description thereof is omitted.

[0140] The coil device 1A has a wire 20A. The wire 20A has a winding portion 21A. The extending direction of the reel O of the winding portion 21A (the reel direction of the winding portion 21A) is inclined with respect to the direction perpendicular to the mounting surface 15 (Z-axis direction). In addition, the reel direction of the winding portion 21A is inclined with respect to the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10. In addition, the reel direction of the winding portion 21A is inclined with respect to the mounting surface 15 and the mounting opposite surface 16.

[0141] The inclination angle θ of the reel direction of the winding portion 21A with respect to the direction perpendicular to the mounting surface 15 (Z-axis direction) is not particularly limited, for example, 0° < θ ≤ 70°, 5° ≤ θ ≤ 60°, or 10° ≤ θ ≤ 50°. The inclination angle θ of the reel direction of the winding portion 21A with respect to the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10 is the same.

[0142] In the present embodiment, the top surface 210a of the winding portion 21A is inclined with respect to the mounting surface 15. Further, the bottom surface 210b of the winding portion 21A is inclined with respect to the mounting surface 15. However, as Figure 6B shown, the top surface 210a of the winding portion 21A may also be parallel to the mounting surface 15. Further, the bottom surface 210b of the winding portion 21A may also be parallel to the mounting surface 15.

[0143] As Figure 6A shown, the buried portion 240 is obliquely led out from the central portion in the Z-axis direction of the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10 toward the base end portion 23. The extending direction of the buried portion 240 is orthogonal to the winding axis direction of the winding portion 21A. However, in the present embodiment, "orthogonal" is not limited to strict orthogonality (i.e., the extending direction of the buried portion 240 intersects the winding axis direction of the winding portion 21A at 90°), and a state deviated by several degrees (not particularly limited, for example, 3 degrees) or less from strict orthogonality is also included in the concept of "orthogonal".

[0144] In the present embodiment, the same effects as those of the first embodiment can also be obtained. Further, in the present embodiment, the winding axis direction of the winding portion 21A is inclined with respect to the direction (Z-axis direction) perpendicular to the mounting surface 15. Therefore, even if the buried portion 240 is bent without being inclined with respect to the base end portion 23 (or even if the bending angle of the buried portion 240 with respect to the base end portion 23 is small), the buried portion 240 can be inclined toward the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10 according to the inclination angle of the winding axis direction of the winding portion 21A. Thus, the buried portion 240 extends obliquely from the base end portion 23 toward the side surface of the magnetic core 10. Therefore, the distance (distance along the Y-axis) between the buried portion 240 and the winding portion 21A can be ensured, and a short-circuit defect between the buried portion 240 and the winding portion 21A can be prevented.

[0145] Further, the buried portion 240 can be inclined toward the side surface of the magnetic core 10 according to the inclination angle of the winding axis direction of the winding portion 21A, so that the terminal portion 242 is exposed from the magnetic core 10 at the central portion of the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10. Moreover, the terminal portion 242 can be arranged from the central portion of the side surface of the magnetic core 10 to the mounting surface 15 in the direction (Z-axis direction) perpendicular to the mounting surface 15. Thus, it is easy to ensure the area of the terminal portion 242 arranged on the side surface of the magnetic core 10 (i.e., the area of the side portion 244), and it is easy to form a solder fillet on the terminal portion 242 (side portion 244) arranged on the side surface of the magnetic core 10. Therefore, the mounting strength of the coil device 1A can be ensured.

[0146] The present disclosure is not limited to the above-described embodiments, and various changes can be made within the scope of the present disclosure.

[0147] In the above-described embodiments, application examples of the present disclosure for inductors have been described, but the present disclosure can also be applied to other coil devices.

[0148] In the above-described embodiments, Figure 4A as shown in etc., the entire region from one end to the other end in the extending direction of the buried portion 240 extends obliquely from the base end portion 23 toward the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10. However, the entire region in the extending direction of the buried portion 240 may not necessarily extend obliquely from the base end portion 23 toward the side surface of the magnetic core 10. For example, a portion that does not extend obliquely from the base end portion 23 toward the side surface of the magnetic core 10 may be included between one end and the other end in the extending direction of the buried portion 240. That is, at least a part of the extending direction of the buried portion 240 may extend obliquely from the base end portion 23 toward the side surface of the magnetic core 10.

Claims

1. A coil device, wherein: have: A magnetic core comprising a magnetic material, having a mounting surface, and a side surface extending in a direction perpendicular to the mounting surface; as well as a conductive wire having a winding portion disposed inside the magnetic core and a lead portion led out from the winding portion, The lead portion includes a base end portion continuous with the winding portion, and a flat portion continuous with the base end portion and flattened into a flat shape. The flat portion includes an embedded portion disposed inside the magnetic core and a terminal portion having a plated layer and disposed outside the magnetic core. The embedded portion extends obliquely from the base end portion toward the side surface, The terminal portion is exposed from the magnetic core at a center portion of the side surface in a direction perpendicular to the mounting surface, and extends from the center portion of the side surface toward the mounting surface.

2. The coil device according to claim 1, wherein: The embedded portion extends from the base end portion to a center portion of the winding portion in a direction perpendicular to the mounting surface.

3. The coil device according to claim 1 or 2, wherein: The embedded portion extends obliquely from the base end portion to the side surface without being bent at a right angle.

4. The coil device according to claim 1 or 2, wherein: The base end portion has an inclined portion, In a cross section perpendicular to the mounting surface and the side surface, the thickness of the inclined portion becomes thinner as it approaches the flat portion.

5. The coil device according to claim 1 or 2, wherein: The lead portion is bent at a boundary between the base end portion and the flat portion, A radius of curvature of the lead-out portion in the boundary portion is greater than a thickness of the flat portion.

6. The coil device according to claim 1 or 2, wherein: The conductor is a round wire or a flat wire. The winding portion has an insulating coating layer.

7. The coil device according to claim 1 or 2, wherein: When viewed from a direction perpendicular to the mounting surface, the outer peripheral surface of the winding portion has a circular shape.

8. The coil device according to claim 1 or 2, wherein: A winding axis direction of the winding portion is inclined relative to a direction perpendicular to the mounting surface.

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