Coil device and manufacturing method thereof

Abstract

The present disclosure provides a coil device capable of preventing the occurrence of short circuit defects and a method of manufacturing the same. The coil device includes: a magnetic core including a magnetic material and 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 extending from the winding portion toward the third side surface, and a flat terminal portion continuous with the base end portion and extending at least along the third side surface. A plating layer is formed on the terminal portion. A recess recessed toward the side opposite to the mounting surface is formed at the periphery of a boundary portion between the base end portion and the terminal portion.

Description

Technical Field

[0001] The present disclosure relates to a coil device and a method for manufacturing the same. 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 terminal portion that is drawn out from the winding portion and flattened into a flat shape. A part of the terminal portion is disposed inside the magnetic core. The remaining part of the terminal 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, a conductive bonding material (such as solder or a conductive adhesive) can be used to connect the terminal portion disposed on the mounting surface to the mounting substrate. That is, since the terminal portion functions as a terminal of the coil device, it is not necessary to additionally provide a terminal in 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] However, in order to improve the adhesion of the bonding material, a plating layer (such as solder plating) is formed on the terminal portion. However, when the plating layer is formed on the terminal portion, for example, due to the heat of reflow, the plating layer of the terminal portion may melt. In this case, there is a possibility that the melted plating layer wets the winding portion through the terminal portion and causes a short-circuit defect.

[0008] The present disclosure provides a coil device and a method for manufacturing the same that can prevent the occurrence of short-circuit defects.

[0009] Means for Solving the Technical Problem

[0010] The present disclosure provides a coil device having:

[0011] 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

[0012] a wire having a winding portion disposed inside the magnetic core and a lead-out portion drawn out from the winding portion,

[0013] the lead-out portion having a base end portion extending from the winding portion toward the side surface and a flat terminal portion continuous with the base end portion and extending at least along the side surface,

[0014] a plating layer is formed on the terminal portion,

[0015] A recess that is recessed toward a side opposite to the mounting surface is formed around a boundary portion between the base end portion and the terminal portion.

[0016] Alternatively, at least a part of the recess may be exposed from the magnetic core.

[0017] Alternatively, the lead-out portion has an inner surface facing the mounting surface or the side surface, and an outer surface opposite to the inner surface, and the recess is formed in the inner surface.

[0018] Alternatively, the base end portion has an inclined portion, at least a part of the inclined portion is exposed from the magnetic core, 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 boundary portion.

[0019] Alternatively, the inclined portion has an inclined surface that inclines toward a side opposite to the mounting surface as it approaches the boundary portion.

[0020] Alternatively, the lead-out portion has an inner surface facing the mounting surface or the side surface, and an outer surface opposite to the inner surface, a part of the recess is formed along the inclined surface, and the remaining part of the recess is formed along the inner surface of the terminal portion.

[0021] Alternatively, the lead-out portion has an inner surface facing the mounting surface or the side surface, and an outer surface opposite to the inner surface, and the plating layer is formed at least on the inner surface in the recess.

[0022] Alternatively, in a cross section perpendicular to the mounting surface and the side surface, the thickness of the lead-out portion is the thinnest in the recess.

[0023] Alternatively, the terminal portion has a side portion extending along the side surface and a mounting portion extending along the mounting surface.

[0024] The present disclosure provides a method for manufacturing a coil device, which includes:

[0025] a step of preparing a wire having a winding portion and a lead-out portion led out from the winding portion;

[0026] a step of flattening the lead-out portion to form a flat terminal portion and an inclined portion having a thickness that becomes thinner as it goes from the winding portion toward the terminal portion;

[0027] a step of disposing the wire in a cavity of a mold and filling the cavity with a magnetic core material containing a magnetic material and a resin in such a manner that the winding portion is embedded;

[0028] a step of compressing the magnetic core material to form a magnetic core;

[0029] A process of forming a coating layer at least on the terminal portion; and

[0030] A process of bending the terminal portion relative to the inclined portion toward the magnetic core around the periphery of the boundary portion between the inclined portion and the terminal portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1A is a perspective view of a coil device according to an embodiment of the present disclosure.

[0032] Figure 1B is a perspective view showing Figure 1A the internal structure of the coil device.

[0033] Figure 1C is Figure 1A a bottom view of the coil device shown in

[0034] Figure 2 is Figure 1B a perspective view of the wire shown in

[0035] Figure 3 is Figure 1B a top view of the coil device shown in

[0036] Figure 4A is a cross-sectional view taken along the line IVA-IVA shown in Figure 3

[0037] Figure 4B is Figure 4A a cross-sectional view of a modified example of the lead-out portion shown in

[0038] Figure 4C Figure 4A is a cross-sectional view of another modified example of the lead-out portion shown in

[0039] Figure 4D Figure 4C is a cross-sectional view of a modified example of the lead-out portion shown in

[0040] Figure 4E is Figure 4C a cross-sectional view of another modified example of the lead-out portion shown in

[0041] Figure 5A is a top view showing Figure 1A the manufacturing method of the coil device shown in

[0042] Figure 5B is a top view showing Figure 5A the subsequent process of the process shown in

[0043] Figure 5C is a top view showing Figure 5BTop view of the subsequent process of the process shown.

[0044] Figure 5D It represents Figure 5C Top view of the subsequent process of the process shown.

[0045] Explanation of reference numerals

[0046] 1... Coil device

[0047] 10... Magnetic core

[0048] 11... First side

[0049] 12... Second side

[0050] 13... Third side

[0051] 14... Fourth side

[0052] 15... Mounting surface

[0053] 16... Opposite mounting surface

[0054] 17a, 17b... First recess

[0055] 18a, 18b... Second recess

[0056] 19... Chamfered portion

[0057] 20... Lead wire

[0058] 21... Winding portion

[0059] 22a, 22b... Lead-out portion

[0060] 22a2, 22b2... Tip portion

[0061] 23... Base end portion

[0062] 230... Inclined portion

[0063] 231a, 231b... Inclined surface

[0064] 232... Non-inclined portion

[0065] 24... Terminal portion

[0066] 240... Side portion

[0067] 241... Mounting portion

[0068] 242... Bending portion

[0069] 25... Inner surface

[0070] 26... Outer surface

[0071] 27, 22a1, 22b1... boundary parts

[0072] 28... concave part

[0073] 29... space

[0074] 30... coating Detailed implementation manners

[0075] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying 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 objects. Additionally, the present disclosure is not limited to the following embodiments.

[0076] 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 wire 20( Figure 1B ). The shape of the magnetic core 10 is not particularly limited. In the Figure 1A shown example, 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 surface 11, a second side surface 12, a third side surface 13, a fourth side surface 14, a mounting surface 15, and a mounting opposite surface 16.

[0077] The edge part between the second side surface 12 and the third side surface 13 is chamfered, and a chamfered part 19 is formed at the edge part between the second side surface 12 and the third side surface 13. By forming the chamfered part 19 on the magnetic core 10, it is easy to identify the orientation of the magnetic core 10. However, the chamfered part 19 is not essential and can also be omitted.

[0078] The first side surface 11 and the second side surface 12 face each other. The third side surface 13 and the fourth side surface 14 face each other. The mounting surface 15 and the mounting opposite surface 16 face each other.

[0079] In Figure 1A etc., the X-axis is the axis along the direction in which the first side surface 11 and the second side surface 12 face each other. The Y-axis is the axis along the direction in which the third side surface 13 and the fourth side surface 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).

[0080] 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.

[0081] 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.

[0082] The magnetic core 10 is made 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 this 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 system ferrite, Mn-Zn system 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.

[0083] 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.

[0084] 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 240 of the lead-out portion 22a described later is disposed in the first recess 17a, and the side portion 240 of the lead-out 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 240 in the X-axis direction.

[0085] The second recesses 18a and 18b are formed on the mounting surface 15. The mounting portion 241 of the lead-out portion 22a described later is disposed in the second recess 18a, and the mounting portion 241 of the lead-out 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 241 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 241. 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.

[0086] AsFigure 1B As shown, the wire 20 has a winding portion 21, a lead-out portion 22a, and a lead-out portion 22b. The wire 20 is, for example, an insulated coated wire in which a conductive core wire is coated with an insulating film (insulation coating layer). As the wire 20, for example, known windings such as AIW (polyamideimide copper wire), UEW (urethane 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 it can also be a flat wire (for example, an edgewise-wound flat wire). The diameter of the wire 20 is not particularly limited and is, for example, 0.3 to 2.0 mm.

[0087] 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 1.5 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 two layers (see Figure 4A ). However, the number of turns of the wire 20 is not particularly limited and can also be 1.5 turns or more (for example, 2.5 turns or 3.5 turns). In addition, the number of layers in the winding axis direction of the winding portion 21 can also be two layers or four layers or more. In the winding portion 21, an insulating film (insulation coating layer) is formed on the surface of the wire 20. 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, but it can also be elliptical or the like.

[0088] The lead-out portion 22a is led out from the second layer in the winding axis direction of the winding portion 21. The lead-out portion 22b is led out from the first layer in the winding axis 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 terminal 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.

[0089] The base end portion 23 and the terminal portion 24 are formed by flattening (stamping or pressing) the lead-out portion 22a or 22b. The terminal 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 terminal portion 24. In other words, unlike the terminal 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 terminal portion 24 will be described.

[0090] The base end portion 23 extends from the winding portion 21 toward the side surface of the magnetic core 10 (the third side surface 13 or the fourth side surface 14). 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 terminal portion 24.

[0091] The base end portion 23 has an inclined portion 230 and a non-inclined portion 232. At least a part of the inclined portion 230 (in Figure 4A the example shown, it is the whole of the inclined portion 230) is exposed from the side surface of the magnetic core 10 (the third side surface 13 or the fourth side surface 14). In a cross-section perpendicular to the mounting surface 15 and the third side surface 13 (i.e., the YZ cross-section), the thickness of the inclined portion 230 (the thickness between the inner surface 25 and the outer surface 26) becomes thinner as it approaches the boundary portion 27 between the base end portion 23 and the terminal portion 24. In the present embodiment, the boundary portion 27 between the base end portion 23 and the terminal portion 24 is exposed from the magnetic core 10 and is not disposed inside the magnetic core 10.

[0092] As Figure 3 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 27 between the base end portion 23 (the inclined portion 230) and the terminal portion 24 ( Figure 4A ).

[0093] 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 upward) as it approaches the boundary portion 27 between the base end portion 23 and the terminal portion 24. 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°.

[0094] 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 27 between the base end portion 23 and the terminal portion 24. 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°.

[0095] 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 the 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.

[0096] However, the non-inclined portion 232 is not essential. The non-inclined portion 232 may also be omitted from the base end portion 23, and the base end portion 23 may also be formed only with the inclined portion 230. For example, the base end portion 23 may be inclined in such a manner that the thickness of the base end portion 23 (the thickness between the inner surface 25 and the outer surface 26) becomes thinner as it approaches the boundary portion 27 between the base end portion 23 and the terminal portion 24 from the boundary portion between the winding portion 21 and the base end portion 23. In this case, one end in the extending direction of the inclined portion 230 is continuous with the winding portion 21, and the other end in the extending direction of the inclined portion 230 is continuous with the terminal portion 24.

[0097] In the inclined portion 230, the coating film of the wire 20 is peeled off, and the inclined surfaces 231a and 231b are not covered with the coating film. However, the coating film may also remain on at least one of the inclined surfaces 231a and 231b. On the other hand, in the non-inclined portion 232, the coating film of the wire 20 is not peeled off, and the surface of the non-inclined portion 232 is covered with the coating film.

[0098] It may also be as Figure 4B shown, a part of the inclined portion 230 is disposed inside the magnetic core 10, and the remaining part of the inclined portion 230 is exposed from the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10. In Figure 4B the example shown, more than 50% of the area of the inclined portion 230 is exposed from the side surface of the magnetic core 10, but an area less than 50% of the inclined portion 230 may also be exposed from the side surface of the magnetic core 10. In addition, it may also be as Figure 4C shown, the inclined portion 230 has the inclined surface 231a, and on the other hand, does not have the inclined surface 231b ( Figure 4A ). In Figure 4C the example shown, the outer surface 26 of the inclined portion 230 is not inclined and is parallel to the mounting surface 15.

[0099] In addition, as Figure 4D shown, in the cross section (i.e., the YZ cross section) perpendicular to the mounting surface 15 and the third side surface 13, the thickness of the terminal portion 24 (the side portion 240) may also gradually become thinner as it approaches the boundary portion 27 between the base end portion 23 and the terminal portion 24. In Figure 4D the example shown, the thickness of the terminal portion 24 is the thinnest at the recess 28.

[0100] As Figure 4AAs shown, the terminal portion 24 is continuous with the base end portion 23 and 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. The thickness of the terminal portion 24 (the thickness between the inner surface 25 and the outer surface 26) is substantially constant along the extending direction of the terminal portion 24. However, "substantially constant" means that the error of the thickness of the terminal portion 24 is within several percent to several tens of percent (not particularly limited, for example, ±10%, or ±5%, or ±3%). In the terminal portion 24, the coating of the wire 20 is peeled off, and the surface of the terminal portion 24 is not covered by the coating of the wire 20. As Figure 2 shown, the terminal 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.

[0101] Figure 2 The width W in the X-axis direction of the terminal portion 24 shown is not particularly limited, for example, it is 1 to 10 mm. The ratio W / Φ of the width W in the X-axis direction of the terminal 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, for example, 1 < W / Φ ≤ 10, or 2 ≤ W / Φ ≤ 8.

[0102] The thickness of the terminal portion 24 is not particularly limited, for example, it is 0.05 to 0.5 mm. The ratio T / Φ of the thickness T of the terminal 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, for example, 1 / 15 ≤ T / Φ ≤ 1 / 2, or 1 / 10 ≤ T / Φ ≤ 1 / 3.

[0103] As Figure 4A shown, the terminal portion 24 has a side portion 240 and a mounting portion 241. The side portion 240 is continuous with the inclined portion 230 and extends along the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10. The side portion 240 has a bent portion 242. In the present embodiment, around the boundary portion 27 between the base end portion 23 and the terminal portion 24, the terminal portion 24 is bent with respect to the inclined portion 230 toward the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10. Therefore, the bent portion 242 is formed at the bending position of the terminal portion 24.

[0104] The bent portion 242 is located at the upper end portion of the side portion 240 and is bent (buckled) in a direction protruding from the side surface (the third side surface 13 or the fourth side surface 14) or the mounting surface 15 of the magnetic core 10. At the bent portion 242, both the inner surface 25 and the outer surface 26 are bent, and a concave portion 28 is formed on the inner surface 25 of the bent portion 242. The bent portion 242 bends from the boundary portion 27 between the base end portion 23 and the terminal portion 24 toward the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10. However, it may also be as Figure 4E shown, the bent portion 242 is bent only around the boundary portion 27. In Figure 4EIn the example shown, the side portion 240 (a portion excluding the bent portion 242 ) extends parallel to the side surface of the magnetic core 10 .

[0105] In addition, in the present embodiment, "parallel" is not limited to strictly parallel, and a state that deviates from strictly parallel by a few degrees (not specifically limited, for example, 3 degrees) or less is also included in the concept of "parallel". In addition, "perpendicular" is not limited to strictly perpendicular, and a state that deviates from strictly perpendicular by a few degrees (not specifically limited, for example, 3 degrees) or less is also included in the concept of "perpendicular".

[0106] like Figure 4A As shown, a portion of the side portion 240 abuts against the side surface (the third side surface 13 or the fourth side surface 14) of the magnetic core 10. However, it is also possible Figure 4E As shown, the side portion 240 does not abut against the side surface of the magnetic core 10 , and a gap may be formed between the side portion 240 and the side surface of the magnetic core 10 .

[0107] The mounting portion 241 is continuous with the side portion 240 and extends in a direction perpendicular to the side portion 240. The mounting portion 241 extends along the mounting surface 15. The mounting portion 241 is a portion connected to a mounting substrate (not shown) by a conductive bonding material (solder, conductive adhesive, etc.).

[0108] like Figure 1A As shown, the mounting portion 241 of the lead portion 22a is arranged in the second recess 18a formed on the mounting surface 15. In addition, the mounting portion 241 of the lead portion 22b is arranged in the second recess 18b formed on the mounting surface 15. In addition, the side portion 240 of the lead portion 22a is arranged in the first recess 17a formed on the third side surface 13. In addition, the side portion 240 of the lead portion 22b is arranged in the first recess 17b formed on the fourth side surface 14.

[0109] like Figure 4A As shown, a plating layer 30 is formed on the inner surface 25 and the outer surface 26 of the lead-out portion 22a. Although detailed illustration is omitted, a plating layer 30 is formed on the inner surface 25 and the outer surface 26 of the lead-out portion 22b. In particular, by forming the plating layer 30 on the outer surface 26, when the coil device 1 is installed, the adhesion of the bonding material (for example, solder or conductive adhesive) relative to the outer surface 26 is improved. The plating layer 30 can be a single layer, or it can be a multiple layer. The plating layer 30 is not particularly limited, and for example, it is Cu plating, Ni plating, Sn plating, Ni-Sn plating, Cu-Ni-Sn plating, Ni-Au plating, Au plating, Sn-Pb plating (solder plating).

[0110] The plating layer 30 is formed on the portion of the base end portion 23 that is exposed from the magnetic core 10, that is, the inclined portion 230. The plating layer 30 is formed on both the inner surface 25 (inclined surface 231a) and the outer surface 26 (inclined surface 231b) of the inclined portion 230, but may be formed on only one of the inner surface 25 and the outer surface 26. For example, the plating layer 30 may not be formed on the inner surface 25 of the inclined portion 230, and the inner surface 25 of the inclined portion 230 may be covered by the coating of the conductive wire 20.

[0111] In addition, the plating layer 30 is formed on both the inner surface 25 and the outer surface 26 of the terminal portion 24. However, the plating layer 30 may not be formed on the inner surface 25 of the terminal portion 24 (the side portion 240 or the mounting portion 241), but may be formed on the outer surface 26 of the terminal portion 24 (the side portion 240 or the mounting portion 241). In this case, the inner surface 25 of the terminal portion 24 (the side portion 240 or the mounting portion 241) may also be covered by the coating of the lead wire 20.

[0112] The plating layer 30 is formed on both the side portion 240 and the mounting portion 241 of the terminal portion 24. However, the plating layer 30 may not be formed on the side portion 240 but may be formed on the mounting portion 241. In this case, the side portion 240 may be covered with the coating of the lead wire 20.

[0113] A recessed portion 28 is formed around the boundary portion 27 between the base end portion 23 and the terminal portion 24 (see Figure 4A (enlarged view in FIG. 1 ). The recess 28 is formed in the inner surface 25 of the lead portion 22a or 22b. The inner surface 25 of the lead portion 22a or 22b is bent or curved along the recess 28 around the boundary 27 between the base end portion 23 and the terminal portion 24. The recess 28 is recessed toward the side opposite to the mounting surface 15 (the mounting opposite surface 16 side or the upper side). Figure 4A In the example shown, the recessed portion 28 is recessed toward the side opposite to the mounting surface 15 and away from the side surface (the third side surface 13 or the fourth side surface 14 ) of the magnetic core 10 .

[0114] The recess 28 is formed by the inclined surface 231a of the base end portion 23 (inclined portion 230) and the inner surface 25 of the terminal portion 24 (side portion 240). That is, a portion of the recess 28 is formed along the inclined surface 231a, and the remaining portion of the recess 28 is formed along the inner surface 25 of the terminal portion 24 (side portion 240). In particular, the recess 28 is formed along the inclined surface 231a and the inner surface 25 of the curved portion 242 (that is, the curved surface of the curved portion 242) around the boundary portion 27 between the base end portion 23 and the terminal portion 24. The bottom of the recess 28 is formed around the boundary portion 27 between the base end portion 23 and the terminal portion 24.

[0115] At least a portion (in this embodiment, the entirety) of the recess 28 is exposed from the magnetic core 10. However, a portion of the recess 28 may be exposed from the magnetic core 10, and the remaining portion of the recess 28 may be disposed inside the magnetic core 10. For example, Figure 4B As shown, when a portion of the inclined portion 230 is disposed inside the magnetic core 10, a portion of the recessed portion 28 is exposed from the magnetic core 10, and the remaining portion of the recessed portion 28 is disposed inside the magnetic core 10. Figure 4A As shown, the bottom of the recessed portion 28 is located away from the side surface (the third side surface 13 or the fourth side surface 14 ) of the magnetic core 10 toward the outside in the Y-axis direction.

[0116] The plated layer 30 is formed in the recessed portion 28. That is, in the recessed portion 28, the plated layer 30 is formed on the inner surface 25 (the inclined surface 231a) of the inclined portion 230. In addition, in the recessed portion 28, the plated layer 30 is formed on the inner surface 25 of the terminal portion 24 (the side portion 240). However, the plated layer 30 may not be formed in the recessed portion 28. In this case, in the recessed portion 28, the inclined surface 231a and the inner surface 25 of the terminal portion 24 may be covered by the coating of the lead wire 20.

[0117] A space 29 is formed inside the recess 28. The space 29 is surrounded by the inclined surface 231a, the inner surface 25 of the terminal portion 24 (side portion 240), and the side surface (third side surface 13 or fourth side surface 14) of the magnetic core 10. In a cross section perpendicular to the mounting surface 15 and the third side surface 13 (i.e., a YZ cross section), the space 29 extends from the bottom of the recess 28 toward the side surface (third side surface 13 or fourth side surface 14) of the magnetic core 10. However, as Figure 4E As shown, the space 29 may also extend along the side surface (the third side surface 13 or the fourth side surface 14 ) of the magnetic core 10 toward the mounting surface 15 .

[0118] Next, refer to Figures 5A - 5D Equal Figure 1B The manufacturing method of the coil device 1 shown in FIG. Figure 5A As shown, a conductor 20 having a winding portion 21 and lead portions 22a and 22b led out from the winding portion 21 is prepared. The conductor 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 are led out from the winding portion 21 toward opposite sides.

[0119] Then, if Figure 5B As shown, the lead portion 22a is flattened, and a flat terminal portion 24 and an inclined portion 230 (see FIG. Figure 4AThe inclined portion 230 has a thickness (thickness between the inner surface 25 and the outer surface 26) that gradually becomes thinner as it moves from the winding portion 21 toward the terminal portion 24. The range of the flattened lead portion 22a is, for example, the range from the boundary 22a1 between the winding portion 21 and the lead portion 22a to the front end 22a2 of the lead portion 22a. Thus, a thin film having a thickness of 22a1 is formed around the boundary 22a1 between the winding portion 21 and the lead portion 22a. Figure 4A The base end portion 23 of the inclined portion 230 is shown. In addition, the terminal portion 24 is formed on the front end side of the lead portion 22a rather than the base end portion 23.

[0120] In addition, if Figure 5B As shown, the lead portion 22b is flattened, and a flat terminal portion 24 and an inclined portion 230 (see FIG. Figure 4A The inclined portion 230 has a thickness that gradually becomes thinner as it moves from the winding portion 21 toward the terminal portion 24. The range of the flattened lead portion 22b is, for example, the range from the boundary portion 22b1 between the winding portion 21 and the lead portion 22b to the front end portion 22b2 of the lead portion 22b. Thus, a thin film having a thickness of 0.04 mm is formed around the boundary portion 22b1 between the winding portion 21 and the lead portion 22b. Figure 4A The base end portion 23 of the inclined portion 230 is shown. In addition, the terminal portion 24 is formed on the front end side of the lead portion 22b rather than the base end portion 23.

[0121] Next, the conductor 20 is placed in the cavity of the mold (not shown), and the cavity is filled with a magnetic core material containing a magnetic material and a resin. At this time, the cavity is filled with the magnetic core material in such a manner that the winding portion 21 is buried in the magnetic core material, at least a portion of the base end portion 23 is exposed from the magnetic core material, and the terminal portion 24 is exposed from the magnetic core material. Next, the magnetic core material filled in the cavity is compressed and cured at a predetermined mold temperature for a predetermined period of time to form a Figure 5C The magnetic core 10 is shown.

[0122] Next, for example, the terminal portion 24 exposed from the core 10 is irradiated with laser light to remove the coating on the surface of the terminal portion 24. Also, for example, the base end portion 23 (inclined portion 230) exposed from the core 10 is irradiated with laser light to remove the coating on the surface of the base end portion 23.

[0123] Then, if Figure 5D As shown in FIG. 1 , a plating layer 30 is formed on the terminal portion 24 exposed from the magnetic core 10. In the present embodiment, the inner surface 25 ( Figure 4A ) and outer surface 26( Figure 4A), but the plating 30 may be formed only on the outer surface 26 of the terminal portion 24. In addition, the plating 30 is formed on the inner surface 25 (inclined surface 231a) and the outer surface 26 (inclined surface 231b) of the base end portion 23 (inclined portion 230) exposed from the magnetic core 10. In the present embodiment, the plating 30 is formed on the inner surface 25 and the outer surface 26 of the base end portion 23, but the plating 30 may be formed only on the outer surface 26 of the base end portion 23. The plating 30 is not particularly limited, and may be, for example, Sn-Pb plating (solder plating). The method for forming the plating 30 is not particularly limited, and may be, for example, electroless plating, electrolytic plating, or dipping. In addition, the process of forming the plating 30 on the terminal portion 24 and / or the base end portion 23 may be performed before the forming of the magnetic core 10 ( Figure 5C before the process shown).

[0124] Then, if Figure 4A As shown, at the periphery of the boundary portion 27 between the base end portion 23 (inclined portion 230) and the terminal portion 24, the terminal portion 24 of the lead portion 22a is bent relative to the base end portion 23 (inclined portion 230) toward the third side surface 13 of the magnetic core 10 (see Figure 4A 14. The side portion 240 of the terminal portion 24 is thus arranged along the third side surface 13. In addition, the terminal portion 24 of the lead portion 22b is bent relative to the base end portion 23 (inclined portion 230) toward the fourth side surface 14 of the magnetic core 10 at the periphery of the boundary portion 27 between the base end portion 23 (inclined portion 230) and the terminal portion 24. Thus, the side portion 240 of the terminal portion 24 is arranged along the fourth side surface 14.

[0125] Next, the front end portion of the terminal portion 24 arranged along the third side surface 13 is bent toward the mounting surface 15 of the magnetic core 10. Thus, the mounting portion 241 of the terminal portion 24 is arranged along the mounting surface 15. In addition, the front end portion of the terminal portion 24 arranged along the fourth side surface 14 is bent toward the mounting surface 15 of the magnetic core 10. Thus, the mounting portion 241 of the terminal portion 24 is arranged along the mounting surface 15. As described above, the coil device 1 can be manufactured.

[0126] When the coil device 1 is manufactured, for example, the plating layer 30 of the terminal portion 24 may melt due to the heat of reflow. Figure 4AAs shown, a recessed portion 28 is formed around the boundary portion 27 between the base end portion 23 and the terminal portion 24, which is recessed toward the side opposite to the mounting surface 15. Therefore, the melted plating 30 (hereinafter referred to as "molten plating") is easily accumulated in the recessed portion 28, and is not easy to wet the winding portion 21 through the terminal portion 24 and the base end portion 23. In addition, since the recessed portion 28 is formed in the lead portion 22a, the creepage distance from the terminal portion 24 to the winding portion 21 becomes longer accordingly, so it is not easy for the molten plating to wet the winding portion 21 through the terminal portion 24 and the base end portion 23. As a result, the molten plating is not easy to adhere to the winding portion 21, and the occurrence of a short circuit defect can be prevented.

[0127] In addition, when the coil device 1 is mounted, when the terminal portion 24 is connected to the mounting substrate (not shown) by using a bonding material (solder or conductive adhesive, etc.), the bonding material may be wetted through the terminal portion 24. In this case, the bonding material is also likely to accumulate in the recessed portion 28, so it is not easy to wet the winding portion 21 through the terminal portion 24 and the base end portion 23. In addition, the recessed portion 28 is formed in the lead portion 22a, and the creepage distance from the terminal portion 24 to the winding portion 21 is correspondingly longer, so it is not easy for the bonding material to wet the winding portion 21 through the terminal portion 24 and the base end portion 23. As a result, the bonding material is not easy to adhere to the winding portion 21, and the occurrence of a short circuit defect can also be prevented in this regard.

[0128] In addition, at least a portion (in this embodiment, the entirety) of the recess 28 is exposed from the magnetic core 10. Therefore, when the coil device 1 is installed, the molten plating or bonding material is easily accumulated in the recess 28 outside the magnetic core 10 and is not easy to enter the inside of the magnetic core 10. As a result, the molten plating or bonding material can be effectively prevented from wetting the winding portion 21.

[0129] In addition, the lead portion 22a has an inner surface 25 facing the mounting surface 15 or the third side surface 13 and an outer surface 26 opposite to the inner surface 25. Moreover, a recessed portion 28 is formed on the inner surface 25. Therefore, the recessed portion 28 is bent (curved) toward the side opposite to the mounting surface 15. Thus, the molten plating or bonding material is easily accumulated in the recessed portion 28, and the molten plating or bonding material can be effectively prevented from wetting the winding portion 21.

[0130] In addition, the base end portion 23 has an inclined portion 230, and at least a portion (in the present embodiment, the entire portion) of the inclined portion 230 is exposed from the magnetic core 10. Moreover, in a cross section (i.e., a 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 boundary portion 27. Therefore, when manufacturing the coil device 1, it is easy to bend the terminal portion 24 relative to the inclined portion 230 around the boundary portion 27 between the inclined portion 230 and the terminal portion 24. Thus, it is easy to form a recessed portion 28 that is recessed toward the side opposite to the mounting surface 15 around the boundary portion 27 between the inclined portion 230 and the terminal portion 24.

[0131] In addition, the inclined portion 230 has an inclined surface 231a, which is inclined toward the side opposite to the mounting surface 15 as it approaches the boundary portion 27. Therefore, when the coil device 1 is manufactured, the concave portion 28 is formed along the inclined surface 231a around the boundary portion 27 between the inclined portion 230 and the terminal portion 24 when the terminal portion 24 is bent relative to the inclined portion 230. Thus, it is easy to form a concave portion 28 that is recessed toward the side opposite to the mounting surface 15 around the boundary portion 27 between the inclined portion 230 and the terminal portion 24. In addition, it is possible to form a concave portion 28 with a depth corresponding to the inclination angle of the inclined surface 231a. Therefore, the storage amount of the molten plating or bonding material in the concave portion 28 can be adjusted according to the depth of the concave portion 28.

[0132] In addition, a part of the recess 28 is formed along the inclined surface 231a, and the remaining part of the recess 28 is formed along the inner surface 25 of the terminal portion 24. Therefore, the recess 28 can be formed so that the bottom of the recess 28 is located around the boundary portion 27 between the inclined portion 230 and the terminal portion 24 and is recessed toward the side opposite to the mounting surface 15. As a result, the molten plating or bonding material is easily accumulated in the recess 28, and the molten plating or bonding material can be effectively prevented from wetting the winding portion 21.

[0133] In addition, the plating layer 30 is formed at least on the inner surface 25 of the recessed portion 28. Therefore, the molten plating or bonding material flowing into the recessed portion 28 is easily accumulated in the recessed portion 28, and is not easy to flow out from the recessed portion 28 toward the winding portion 21. Thus, the molten plating or bonding material can be effectively prevented from wetting the winding portion 21.

[0134] In addition, if Figure 4D As shown, in the cross section (i.e., YZ cross section) perpendicular to the mounting surface 15 and the third side surface 13, the thickness of the lead portion 22a or 22b is thinnest in the recess 28. Therefore, a deeper recess 28 can be formed toward the side opposite to the mounting surface 15, making it easy for the molten plating or bonding material to accumulate in the recess 28.

[0135] In addition, if Figure 4A As shown, the terminal portion 24 has a side portion 240 extending along the third side surface 13 and a mounting portion 241 extending along the mounting surface 15. Therefore, the mounting portion 241 can be connected to the mounting substrate using a bonding material. In addition, a fillet of the bonding material can be formed on the side portion 240, thereby improving the mounting strength of the coil device 1.

[0136] In addition, in the manufacturing method of the coil device 1 of the present embodiment, the terminal portion 24 is bent relative to the inclined portion 230 toward the magnetic core 10 at the periphery of the boundary portion 27 between the inclined portion 230 and the terminal portion 24. Therefore, the recessed portion 28 recessed toward the side opposite to the mounting surface 15 can be formed along the inclined portion 230 and the terminal portion 24 at the periphery of the boundary portion 27 between the inclined portion 230 and the terminal portion 24. As a result, when the coil device 1 is mounted, the molten plating or bonding material is easily accumulated in the recessed portion 28, and the molten plating or bonding material can be prevented from wetting the winding portion 21.

[0137] The present disclosure is not limited to the above-described embodiments, and various modifications can be made within the scope of the present disclosure.

[0138] In the above-mentioned respective embodiments, examples in which the present disclosure is applied to an inductor are described, but the present disclosure can also be applied to other coil devices.

[0139] Figures 4C - 4E The inclined portion 230 shown in FIG. 1 has one inclined surface 231a, but may also have two inclined surfaces 231a and 231b (see FIG. 2A ). Figure 4A ).in addition, Figures 4C - 4E The inclined portion 230 is shown as a whole exposed from the magnetic core 10, but may be partially exposed from the magnetic core 10 (see Figure 4B ).Right now, Figures 4C - 4E A portion of the inclined portion 230 shown may also be disposed inside the magnetic core 10 .

Claims

1. A coil device, wherein: have: A magnetic core comprising a magnetic material and 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 extending from the winding portion toward the side surface, and a flat terminal portion continuous with the base end portion and extending at least along the side surface. A plating layer is formed on the terminal portion, A recessed portion that is recessed toward a side opposite to the mounting surface is formed around a boundary portion between the base end portion and the terminal portion.

2. The coil device according to claim 1, wherein: At least a portion of the recess is exposed from the magnetic core.

3. The coil device according to claim 1 or 2, wherein: The lead-out portion has an inner surface facing the mounting surface or the side surface, and an outer surface opposite to the inner surface. The recess is formed on the inner surface.

4. The coil device according to claim 1 or 2, wherein: The base end portion has an inclined portion, At least a portion of the inclined portion is exposed from the magnetic core, In a cross section perpendicular to the mounting surface and the side surface, the thickness of the inclined portion decreases as it approaches the boundary portion.

5. The coil device according to claim 4, wherein: The inclined portion has an inclined surface that is inclined toward a side opposite to the mounting surface as it approaches the boundary portion.

6. The coil device according to claim 5, wherein: The lead-out portion has an inner surface facing the mounting surface or the side surface, and an outer surface opposite to the inner surface. A portion of the recess is formed along the inclined surface, A remaining portion of the recess is formed along the inner surface of the terminal portion.

7. The coil device according to claim 1 or 2, wherein: The lead-out portion has an inner surface facing the mounting surface or the side surface, and an outer surface opposite to the inner surface. In the recessed portion, the plating layer is formed at least on the inner surface.

8. The coil device according to claim 1 or 2, wherein: In a cross section perpendicular to the mounting surface and the side surface, the thickness of the lead portion is thinnest at the recessed portion.

9. The coil device according to claim 1 or 2, wherein: The terminal portion includes a side portion extending along the side surface and a mounting portion extending along the mounting surface.

10. A method for manufacturing a coil device, wherein: have: a step of preparing a conductive wire having a winding portion and a lead portion led out from the winding portion; The step of flattening the lead portion to form a flat terminal portion and an inclined portion having a thickness that decreases from the winding portion toward the terminal portion; The step of placing the conductive wire in a cavity of a mold and filling the cavity with a magnetic core material including a magnetic material and a resin so as to bury the winding portion; A step of compressing the magnetic core material to form a magnetic core; A step of forming a plating layer at least on the terminal portion; and The step of bending the terminal portion toward the magnetic core relative to the inclined portion in the vicinity of a boundary portion between the inclined portion and the terminal portion.

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