Coil device

Abstract

To provide a coil device that is excellent in inductance characteristics.SOLUTION: A coil device 1 has: a core 2; a coil 3 that has a wound part 30 arranged in the core 2, and a lead-out part 5a led out from the wound part 30; and a terminal 4a bonded to the lead-out part 5a and that has a wire connection part 40a arranged in the core 2. The wire connection part 40a is arranged substantially in parallel to a winding axis of the coil 3.SELECTED DRAWING: Figure 2A

Description

Technical Field

[0001] This application relates to a coil device.

Background Art

[0002] For example, as shown in Patent Document 1, a coil device in which a wire connection portion of a terminal is disposed inside a core is known. In this type of coil device, since the wire connection portion is not exposed outside the core, the wire connection portion can be protected from the risk of contact with other components.

[0003] However, when the wire connection portion is disposed inside the core, there is a risk that the wire connection portion blocks the magnetic flux path because the wire connection portion protrudes into the magnetic flux path. In this case, a problem occurs in that the flow of magnetic flux is obstructed by the wire connection portion, and the inductance characteristics of the coil device deteriorate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In view of such a situation, this application is made, and its object is to provide a coil device having excellent inductance characteristics.

Means for Solving the Problems

[0006] To achieve the above object, the coil device according to this application includes a core, a coil having a winding portion disposed inside the core and a lead-out portion drawn from the winding portion, and a terminal having a wire connection portion joined to the lead-out portion and disposed inside the core. The aforementioned connecting wire section is arranged substantially parallel to the winding axis of the coil.

[0007] In the coil device according to this application, the connecting wire section is arranged substantially parallel to the winding axis of the coil. Therefore, the protrusion of the magnetic flux from the connecting wire section into the passage is reduced, and the overlap between the connecting wire section and the magnetic flux passage is suppressed. As a result, the flow of magnetic flux is less likely to be obstructed by the connecting wire section, and the inductance characteristics of the coil device can be improved.

[0008] The connecting portion may be arranged substantially parallel to one or the other surface of the core, facing the winding shaft in a direction substantially perpendicular to it. In this case, the connecting portion is arranged in a predetermined orientation so as to direct the magnetic flux to a region where the magnetic flux is relatively small. As a result, the protrusion of the magnetic flux from the connecting portion into the passage is further reduced, and the connecting portion is less likely to obstruct the passage of magnetic flux.

[0009] A portion of the terminal is exposed from one or the other surface of the core, and the connecting portion may be arranged substantially parallel to one or the other surface of the core. In this case, the structure of the connecting portion can be simplified and the terminal can be made more compact.

[0010] With respect to the winding axis of the coil, one end of the connecting portion may be positioned approximately equal to one end of the coil. In this case, with respect to the winding axis of the coil, the range of the connecting portion to which the lead portion can be joined is extended to a position approximately equal to one end of the coil. Therefore, the lead portion can be joined to the connecting portion with a relatively high pressure, and the joint stability between the lead portion and the connecting portion can be improved.

[0011] The lead portion may be joined to the first surface of the connecting portion facing the coil. In this case, compared to joining the lead portion to the second surface opposite to the first surface, the lead portion can be drawn out to the position of the connecting portion (first surface) over a shorter distance, thereby reducing the resistance of the lead portion.

[0012] The core has a corner where a plurality of surfaces arranged substantially parallel to the winding axis of the coil intersect, and at least a portion of the connecting wire portion may be located at the corner. In this case, at least a portion of the connecting wire portion is positioned relatively far from the magnetic flux path. Therefore, the protrusion of the connecting wire portion into the magnetic flux path is further reduced, and the connecting wire portion is less likely to obstruct the magnetic flux path.

[0013] The aforementioned corner portion has a first corner portion and a second corner portion located on the opposite side of the first corner portion along a direction substantially perpendicular to the winding axis of the coil, and the connecting portion has a first connecting piece to which the lead portion is joined and a second connecting piece located on the opposite side of the first connecting piece along a direction substantially perpendicular to the winding axis of the coil, the first connecting piece may be located in the first corner portion and the second connecting piece may be located in the second corner portion. In this case, the first connecting piece and the second connecting piece are located relatively far from the magnetic flux path. Therefore, the protrusion of the connecting portion into the magnetic flux path is further reduced, and the connecting portion is less likely to obstruct the magnetic flux path.

[0014] The lead portion may be biased by its elastic force so as to press against the connecting portion. In this case, when joining the lead portion to the connecting portion, the lead portion can be temporarily fixed to the connecting portion by the elastic force of the lead portion.

[0015] The lead-out section has a joint that is joined to the connecting section, and the coil is made of flat-wound rectangular wire, and the wide surface of the rectangular wire may constitute the joining surface of the joint. In this case, the joining area between the joint and the connecting section can be increased, and the joint stability between the joint and the connecting section can be improved.

[0016] The lead-out portion has a jointed portion joined to the connecting portion and a non-jointed portion spaced apart from the jointed portion, and the first thickness of the jointed portion may be smaller than the second thickness of the non-jointed portion. In this case, since the jointed portion is compressed in the thickness direction, it is possible to join the jointed portion compactly to the connecting portion. Therefore, the volume of cores that can be placed around the jointed portion is increased, and the inductance characteristics of the coil device can be improved.

[0017] The third thickness of the joint portion may be greater than the first thickness of the joint portion. In this case, since the third thickness of the joint portion is relatively larger, it becomes possible to ensure the physical strength of the joint portion and improve the joint stability between the joint portion and the joint portion.

[0018] The first width of the joint may be greater than the second width of the non-jointed portion. In this case, since the first width of the joint is relatively larger, the joining area between the joint and the connecting portion can be increased, and the joint stability between the joint and the connecting portion can be improved.

[0019] The third width of the connecting portion may be greater than the first width of the joint portion. In this case, since the third width of the connecting portion is relatively larger, the joint portion is less likely to protrude outward in the width direction of the connecting portion, and the joint stability between the joint portion and the connecting portion can be improved.

[0020] The terminal has a first terminal and a second terminal, the connecting portion has a first connecting portion provided on the first terminal and a second connecting portion provided on the second terminal, and the lead portion has a first lead portion and a second lead portion, and the first lead portion and the second lead portion may be joined to the first connecting portion and the second connecting portion, respectively, on the same side of the core in the first direction. In this case, it becomes possible to join the first lead portion to the first connecting portion and the second lead portion to the second connecting portion from the same direction (the same side of the core in the first direction), thereby facilitating the manufacture of the coil device. Furthermore, the pressing force on the first lead portion and the second lead portion can be made uniform, and variations in the characteristics of the coil device can be suppressed.

[0021] The first lead-out portion and the second lead-out portion may be joined to one end portion in the first direction of the first connection line portion and one end portion in the first direction of the second connection line portion, respectively. At one end portion in the first direction of the first connection line portion and one end portion in the first direction of the second connection line portion, compared with other positions, the first lead-out portion and the second lead-out portion can be pressure-joined to the first connection line portion and the second connection line portion, respectively, with a relatively high pressing force, so that the joining stability between them can be improved.

Brief Description of the Drawings

[0022] [Figure 1] FIG. 1 is a perspective view of a coil device according to a first embodiment. [Figure 2A] FIG. 2A is a perspective view showing the internal structure of the coil device shown in FIG. 1. [Figure 2AA] FIG. 2AA is a cross-sectional view taken along line A-A of the non-joined portion shown in FIG. 2A. [Figure 2AB] FIG. 2AB is a cross-sectional view taken along line B-B of the joined portion shown in FIG. 2A. [Figure 3] FIG. 3 is a perspective view of the coil shown in FIG. 2A. [Figure 4] FIG. 4 is a perspective view of the terminal shown in FIG. 2A. [Figure 5A] FIG. 5A is a cross-sectional view taken along line VA-VA of the coil device shown in FIG. 2A. [Figure 5B] FIG. 5B is a cross-sectional view of a modified example of the coil device shown in FIG. 5A. [Figure 6] FIG. 6 is a plan view of the coil device shown in FIG. 2A. [Figure 7A] FIG. 7A is a cross-sectional view showing the peripheral structure of the joined portion shown in FIG. 2A. [Figure 7B] FIG. 7B is a perspective view showing the surface state of the joined portion shown in FIG. 7A. [Figure 7C] FIG. 7C is a cross-sectional view taken along line VIIC-VIIC of the structure shown in FIG. 7B. [Figure 7D] FIG. 7D is a cross-sectional view of a modified example of the peripheral structure of the joined portion shown in FIG. 7A. [Figure 8A]Figure 8A shows the manufacturing method for the coil device shown in Figure 1. [Figure 8B] Figure 8B shows the process following Figure 8A. [Figure 8C] Figure 8C shows the continuation of the process shown in Figure 8B. [Figure 8D] Figure 8D shows the process following Figure 8C. [Figure 9] Figure 9 is a perspective view of the coil device of the second embodiment. [Figure 10] Figure 10 is a perspective view of the terminals shown in Figure 9. [Figure 11] Figure 11 is a side view of the coil device of the third embodiment. [Modes for carrying out the invention]

[0023] Embodiments of this application will be described with reference to the drawings. While the drawings will be referenced as necessary, the illustrations are provided for illustrative purposes only to aid in understanding this application, and the appearance and dimensional ratios may differ from those of the actual product. Furthermore, while the embodiments will be described in detail below, the invention is not limited to these embodiments.

[0024] First Embodiment As shown in Figure 1, the coil device 1 of the first embodiment is, for example, a surface-mount type inductor and is mounted on various electronic devices.

[0025] As shown in Figure 2A, the coil device 1 includes a core 2, a coil 3, and terminals 4a and 4b. The core 2 is substantially rectangular in shape and has a first face 2a, a second face 2b, a third face 2c, a fourth face 2d, a fifth face 2e, and a sixth face 2f. In the drawing, the direction in which the first face 2a and the second face 2b face each other is defined as the X-axis direction (first direction), the direction in which the third face 2c and the fourth face 2d face each other is defined as the Y-axis direction (second direction), and the direction in which the fifth face 2e and the sixth face 2f face each other is defined as the Z-axis direction (third direction).

[0026] The dimensions of the coil device 1 are not particularly limited, but the length in the X-axis direction is, for example, 2 to 20 mm, the length in the Y-axis direction is, for example, 2 to 20 mm, and the length in the Z-axis direction is, for example, 1 to 10 mm.

[0027] Core 2 is formed from a material containing a magnetic material and a resin. Examples of magnetic materials forming Core 2 include ferrite particles or metallic magnetic particles. Examples of ferrite particles include Ni-Zn ferrite and Mn-Zn ferrite. Examples of metallic magnetic particles are not particularly limited, but include Fe-Ni alloy powder, Fe-Si alloy powder, Fe-Si-Cr alloy powder, Fe-Co alloy powder, Fe-Si-Al alloy powder, amorphous iron, etc. Examples of resins forming Core 2 are not particularly limited, but include epoxy resin, phenolic resin, polyester resin, polyurethane resin, polyimide resin, other synthetic resins, or other non-magnetic materials. Core 2 may also be a sintered body of a metallic magnetic material.

[0028] Core 2 is formed by powder compaction or injection molding, etc. The shape of Core 2 is not limited to a roughly rectangular parallelepiped shape, but may be other polygonal shapes or roughly cylindrical shapes. Furthermore, Core 2 may be formed by combining (compression molding) multiple molded bodies (multiple layers).

[0029] As shown in Figure 3, the coil 3 is an air-core coil and is formed from an insulated round wire. The wire material can be copper, silver, alloys containing these, or other metals or alloys. The diameter of the wire is, for example, 10 to 80 μm. At least a portion of the wire (for example, the lead-outs 5a and 5b) may be exposed from the insulating coating. The winding axis direction of the winding portion 30 of the coil 3 corresponds to the Z-axis direction and is perpendicular to the fifth surface 2e and the sixth surface 2f of the core 2 (Figure 2A). The number of turns of the winding portion 30 is not particularly limited and can be one turn or more.

[0030] As shown in Figure 2A, the coil 3 is embedded inside the core 2. The coil 3 has a winding section 30 formed by winding a wire, a lead-out section 5a extending from the winding section 30 to one end of the wire, and a lead-out section 5b extending from the winding section 30 to the other end of the wire.

[0031] The lead-out portion 5a has a joint portion 50a that is joined to terminal 4a and an unjointed portion 51a that is not joined to terminal 4a. The unjointed portion 51a is the portion located between the winding portion 30 of coil 3 and the joint portion 50a (the portion located at a distance from the joint portion 50a). The lead-out portion 5b has a joint portion 50b that is joined to terminal 4b and an unjointed portion 51b that is not joined to terminal 4b. The unjointed portion 51b is the portion located between the winding portion 30 of coil 3 and the joint portion 50b (the portion located at a distance from the joint portion 50b).

[0032] The lead portion 5a is led out toward the second surface 2b of the core 2. Similarly, the lead portion 5b is led out toward the second surface 2b of the core 2. That is, in this embodiment, the lead portions 5a and 5b are led out in the same direction. However, these lead directions may be opposite with respect to the X-axis direction. The lead portions 5a and 5b are joined to terminals 4a and 4b, respectively.

[0033] Terminals 4a and 4b are spaced apart in the Y-axis direction. As shown in Figure 4, terminal 4a has a connecting portion 40a, a first connecting portion 45a, a second connecting portion 46a, and an external electrode portion 47a, but is not limited to these, and in one embodiment, terminal 4a may have only a connecting portion 40a. Similarly, terminal 4b has a connecting portion 40b, a first connecting portion 45b, a second connecting portion 46b, and an external electrode portion 47b, but is not limited to these, and in one embodiment, terminal 4b may have only a connecting portion 40b. Terminals 4a and 4b may have the same shape or different shapes.

[0034] As shown in Figure 2A, the external electrode portions 47a and 47b are arranged on the fifth surface 2e of the core 2, spaced apart in the Y-axis direction. The coil device 1 may be mounted on an external substrate, for example, via the external electrode portions 47a and 47b. The external electrode portions 47a and 47b may be connected to the land pattern of the external substrate, for example, by solder or conductive adhesive.

[0035] The first connection portion 45a is located on the third surface 2c of the core 2 and is perpendicular to the external electrode portion 47a. The first connection portion 45a extends along the Z-axis direction on the third surface 2c. The first connection portion 45b is located on the fourth surface 2d of the core 2 and is perpendicular to the external electrode portion 47b. The first connection portion 45b extends along the fourth surface 2d for a predetermined length. The first connection portion 45a and the first connection portion 45b face each other in the Y-axis direction.

[0036] The length of the first connection portion 45a in the Z-axis direction is shorter than the length of the core 2 in the Z-axis direction. The length of the first connection portion 45b in the Z-axis direction is also shorter than the length of the core 2 in the Z-axis direction. Solder fillets, for example, can be formed on the first connection portion 45a and the first connection portion 45b.

[0037] The second connection portion 46a is located inside the core 2 and is perpendicular to the first connection portion 45a. The second connection portion 46b is located inside the core 2 and is perpendicular to the first connection portion 45b. Of the second connection portion 46a, the portion connected to the first connection portion 45a is exposed from the core 2, while the rest of the portion is located inside the core 2. Similarly, of the second connection portion 46b, the portion connected to the first connection portion 45b is exposed from the core 2, while the rest of the portion is located inside the core 2.

[0038] The lengths of the first connection portion 45a, the second connection portion 46a, and the external electrode portion 47a in the X-axis direction are approximately equal, but may be different. In this embodiment, the lengths of the first connection portion 45a, the second connection portion 46a, and the external electrode portion 47a in the X-axis direction are, for example, less than or equal to half the width of the core 2 in the X-axis direction.

[0039] The lengths of the first connection portion 45b, the second connection portion 46b, and the external electrode portion 47b in the X-axis direction are approximately equal, but may be different. In this embodiment, the lengths of the first connection portion 45b, the second connection portion 46b, and the external electrode portion 47b in the X-axis direction are, for example, less than or equal to half the width of the core 2 in the X-axis direction.

[0040] The connecting sections 40a and 40b have a flat plate shape and are arranged inside the core 20. The connecting section 50a of the lead section 5a is joined to at least a portion of the connecting section 40a, and the connecting section 50b of the lead section 5b is joined to at least a portion of the connecting section 40b.

[0041] The connecting wire section 40a is connected to the external electrode section 47a via the first connecting section 45a and the second connecting section 46a. The connecting wire section 40b is connected to the external electrode section 47b via the first connecting section 45b and the second connecting section 46b.

[0042] The connecting portion 40a is positioned parallel to the third surface 2c of the core 2 where the first connection portion 45a is exposed. The connecting portion 40b is positioned parallel to the fourth surface 2d of the core 2 where the first connection portion 45b is exposed. Furthermore, the connecting portions 40a and 40b are positioned parallel to the winding axis of the coil 3. In this embodiment, parallelism means that a variation of ±5% or less is permitted.

[0043] The connecting sections 40a and 40b are positioned perpendicular to the sixth surface 2f of the core 2 so as to direct the magnetic flux towards a region where the magnetic flux is relatively small. As a result, the overhang of the magnetic flux from the connecting sections 40a and 40b (especially the ends of the connecting sections 40a and 40b on the positive Z-axis side) into the magnetic flux path is reduced, and the connecting sections 40a and 40b are less likely to obstruct the magnetic flux path. In this embodiment, perpendicularity means that a variation of ±5% or less is permitted.

[0044] Furthermore, compared to the case where the connecting sections 40a and 40b are arranged parallel to the second surface 2b of the core 2, for example, the structure of the connecting sections 40a and 40b can be simplified, and the terminals 4a and 4b can be made more compact.

[0045] The connecting sections 40a and 40b have a first surface 401 that faces the coil 3 and a second surface 402 that faces the opposite side of the coil 3. The first surface 401 and the second surface 402 are arranged parallel to the third surface 2c and the fourth surface 2d of the core 2.

[0046] As shown in Figure 4, the connecting section 40a has a first connecting piece 41a, a second connecting piece 42a, an intermediate section 43a, and a curved section 44a. The connecting section 40b also has a first connecting piece 41b, a second connecting piece 42b, an intermediate section 43b, and a curved section 44b.

[0047] The curved portion 44a is formed on the outer edge of the connecting portion 40a on the side opposite in the Z-axis direction from the side to which the second connecting portion 46a is connected. The curved portion 44a may be formed, for example, spanning the first connecting piece 41a, the intermediate portion 43a, and the second connecting piece 42a.

[0048] The curved portion 44b is formed on the outer edge of the connecting portion 40b on the side opposite in the Z-axis direction from the side to which the second connecting portion 46b is connected. The curved portion 44b may be formed across, for example, the first connecting piece 41b, the intermediate portion 43b, and the second connecting piece 42b.

[0049] The intermediate section 43a is located along the X-axis direction between the first connecting wire piece 41a and the second connecting wire piece 42a, and connects them. The intermediate section 43b is located along the X-axis direction between the first connecting wire piece 41b and the second connecting wire piece 42b, and connects them.

[0050] The first connecting piece 41a and the second connecting piece 42a have the same shape, but their shapes may be different. Similarly, the first connecting piece 41b and the second connecting piece 42b have the same shape, but their shapes may be different. As shown in Figure 5A, the ends of the first connecting piece 41a and the first connecting piece 41b on the sixth surface 2f side are positioned at a distance D1 in the Z-axis direction from the sixth surface 2f of the core 2. The distance D1 is, for example, 1 / 8 or more and less than 1 / 2 of the width W in the Z-axis direction of the core 2. When D2 is the distance between the sixth surface 2f of the core 2 and the Z-axis direction end of the coil 3 on the sixth surface 2f side, D1 ≥ D2 is also acceptable.

[0051] With respect to the Z-axis direction, the Z-positive end of the first splice piece 41a and the first splice piece 41b is positioned approximately equal to the Z-positive end of the winding section 30. Therefore, with respect to the Z-axis direction, the range of the first splice piece 41a and the first splice piece 41b to which the joints 50a and 50b can be joined is extended to a position approximately equal to the Z-positive end of the winding section 30. As a result, the joints 50a and 50b can be joined to the first splice piece 41a and the first splice piece 41b, respectively, with relatively high pressure, and the joint stability between them can be improved. Note that the Z-positive end of the first splice piece 41a and the first splice piece 41b may be located on the fifth surface 2e side of the core 2 than the Z-positive end of the winding section 30. Furthermore, the position approximately equal to the Z-positive end of the winding section 30 includes a variation of 1 to 2 wires relative to the position of the end.

[0052] As shown in Figure 6, the joint portion 50a of the lead portion 5a may be joined to one side of the center of the first connecting wire piece 41a in the X-axis direction (one end of the connecting wire portion 40a in the X-axis direction). Similarly, the joint portion 50b of the lead portion 5b may be joined to one side of the center of the first connecting wire piece 41b in the X-axis direction (one end of the connecting wire portion 40b in the X-axis direction). In such positions, the joint portions 50a and 50b can be pressurized and joined to the first connecting wire pieces 41a and 41b with a relatively high pressure compared to other positions, thereby improving the joint stability between them.

[0053] Furthermore, both the joint portion 50a and the joint portion 50b may be joined to the first connecting wire piece 41a and the first connecting wire piece 41b on the same side (second surface 2b side) in the X-axis direction of the core 2. In this case, it becomes possible to join the joint portion 50a to the first connecting wire piece 41a and the joint portion 50b to the first connecting wire piece 41b from the same direction (same side in the X-axis direction). Therefore, it is possible to facilitate the manufacturing of the coil device 1 and to equalize the pressure applied to the joint portion 50a and the joint portion 50b, thereby suppressing manufacturing variations of the coil device 1.

[0054] The first connecting piece 41a (in particular, the joining position between the joint 50a and the first connecting piece 41a) may be located near the intersection of the second surface 2b and the third surface 2c of the core 2 (corner 2g of the core 2). For example, the first connecting piece 41a (in particular, the joining position with the joint 50a) may be located within 40% of the width of the third surface 2c in the X-axis direction (or the width of the second surface 2b in the Y-axis direction), or within 30% of the width of the third surface 2c in the X-axis direction (or the width of the second surface 2b in the Y-axis direction), centered on the intersection.

[0055] Furthermore, the first connecting piece 41b (in particular, the joining position between the joint 50b and the first connecting piece 41b) may be located near the intersection of the second surface 2b and the fourth surface 2d of the core 2 (corner 2h of the core 2). For example, the first connecting piece 41b (in particular, the joining position with the joint 50b) may be located within 40% of the width of the fourth surface 2d in the X-axis direction (or the width of the second surface 2b in the Y-axis direction), or within 30% of the width of the fourth surface 2d in the X-axis direction (or the width of the second surface 2b in the Y-axis direction), centered on the intersection.

[0056] By positioning the first connecting wire pieces 41a and 41b at corners 2g and 2h of the core 2, respectively, the first connecting wire pieces 41a and 41b are positioned relatively far from the magnetic flux path. Therefore, the protrusion of the first connecting wire pieces 41a and 41b into the magnetic flux path is reduced, and they are less likely to obstruct the magnetic flux path.

[0057] The second connecting piece 42a may be located near the intersection of the first surface 2a and the third surface 2c of the core 2 (at the corner 2i of the core 2). For example, the second connecting piece 42a may be located within a range of 40% of the width of the third surface 2c in the X-axis direction (or the width of the first surface 2a in the Y-axis direction) centered on the intersection, or within a range of 30% of the width of the third surface 2c in the X-axis direction (or the width of the first surface 2a in the Y-axis direction).

[0058] Furthermore, the second connecting piece 42b may be located near the intersection of the first surface 2a and the fourth surface 2d of the core 2 (at the corner 2j of the core 2). For example, the second connecting piece 42b may be located within 40% of the width of the fourth surface 2d in the X-axis direction (or the width of the first surface 2a in the Y-axis direction) centered on the intersection, or within 30% of the width of the fourth surface 2d in the X-axis direction (or the width of the first surface 2a in the Y-axis direction).

[0059] In this case, the first connecting piece 41a and the first connecting piece 41b are positioned at corners 2g and 2h, respectively, and the second connecting piece 42a and the second connecting piece 42b are positioned at corners 2i and 2j, respectively. Therefore, both the first connecting piece 41a and the first connecting piece 41b and the second connecting piece 42a and the second connecting piece 42b are positioned relatively far from the magnetic flux path. As a result, the overhang of the first connecting piece 41a and the first connecting piece 41b and the second connecting piece 42a and the second connecting piece 42b into the magnetic flux path is further reduced, making them less likely to obstruct the magnetic flux path.

[0060] The extension portion 5a may be biased by its elastic force so as to press against the first connecting piece 41a. Similarly, the extension portion 5b may be biased by its elastic force so as to press against the first connecting piece 41b. In this case, when joining the joint portions 50a and 50b to the first connecting piece 41a and 41b, the elastic force of the extension portions 5a and 5b can temporarily fix the joint portions 50a and 50b to the first connecting piece 41a and 41b.

[0061] The joints 50a and 50b may be joined to the first surface 401 (the surface facing the coil 3) of the first connecting piece 41a and 41b, respectively. In this case, compared to joining the joints 50a and 50b to the second surface 402 of the first connecting piece 41a and 41b, the joints 50a and 50b can be drawn out to the position of the first connecting piece 41a and 41b over a shorter distance, thereby reducing the resistance of the lead-out portions 5a and 5b.

[0062] As shown in Figure 2AB, in the cross-section (YZ section) perpendicular to the extension direction (X-axis direction) of the joint portion 50a and the joint portion 50b, the joint portion 50a and the joint portion 50b have a flattened shape.

[0063] On the other hand, as shown in Figure 2AA, in a cross-section perpendicular to the extension direction of the non-jointed portions 51a and 51b, the non-jointed portions 51a and 51b have a wire shape consisting of a substantially circular shape. Furthermore, the non-jointed portions 51a and 51b may be deformed in the vicinity of the jointed portions 50a and 50b into, for example, a substantially elliptical shape (a substantially elliptical shape with a major axis in the width direction).

[0064] In this embodiment, since the cross-sectional area of ​​the joint 50a is smaller than the cross-sectional area of ​​the non-joint 51a, the joint area between the joint 50a and the first connecting wire piece 41a increases, and an improvement in connection stability between them is expected. Similarly, since the cross-sectional area of ​​the joint 50b is smaller than the cross-sectional area of ​​the non-joint 51b, the joint area between the joint 50b and the first connecting wire piece 41b increases, and an improvement in connection stability between them is expected.

[0065] As shown in Figures 2AA and 2AB, the thickness L1 of the joint 50a and joint 50b is smaller than the thickness L2 of the non-jointed parts 51a and non-jointed parts 51b. This is because the joint 50a and joint 50b are compressed in the thickness direction when joined to the first connecting wire piece 41a and the first connecting wire piece 41b.

[0066] Note that the thickness L1 of the joint portion 50a is the length in the Y-axis direction between the joint surface of the joint portion 50a joined to the first connection piece 41a and the surface on the opposite side in the Y-axis direction thereof. Also, the thickness L1 of the joint portion 50b is the length in the Y-axis direction between the joint surface of the joint portion 50b joined to the first connection piece 41b and the surface on the opposite side in the Y-axis direction thereof. The thickness L2 of the non-joint portion 51a is the length in the direction corresponding to the thickness L1 of the joint portion 50a shown in FIG. 2AB in a cross-section orthogonal to the extending direction of the non-joint portion 51a shown in FIG. 2AA. Also, the thickness L2 of the non-joint portion 51b is the length in the direction corresponding to the thickness L1 of the joint portion 50b shown in FIG. 2AB in a cross-section orthogonal to the extending direction of the non-joint portion 51b shown in FIG. 2AA.

[0067] The aspect ratio L3 / L1 of the joint portion 50a may be, for example, 1 < L3 / L1 ≤ 10, or may be 1 < L3 / L1 ≤ 5. By pressing the joint portion 50a and the joint portion 50b so that the value of L3 / L1 falls within the above range, the joint strength between the joint portion 50a and the joint portion 50b and the first connection piece 41a and the first connection piece 41b can be improved.

[0068] The ratio L1 / L2 of these lengths may be, for example, 1 / 50 ≤ L1 / L2 < 1, or may be, for example, 1 / 50 ≤ L1 / L2 < 1 / 2. By pressing the joint portion 50a and the joint portion 50b so that the value of L1 / L2 falls within the above range, the joint strength between the joint portion 50a and the joint portion 50b and the first connection piece 41a and the first connection piece 41b can be improved.

[0069] The widths L3 of the joint portion 50a and the joint portion 50b are larger than the widths L4 of the non-joint portion 51a and the non-joint portion 51b. As described above, as a result of the joint portion 50a and the joint portion 50b being compressed in the thickness direction, the joint portion 50a and the joint portion 50b are rolled in the width direction.

[0070] Note that the width L3 of the joint portion 50a is the length of the joint portion 50a in the Z-axis direction (the length in the direction orthogonal to the thickness direction of the joint portion 50a). Also, the width L3 of the joint portion 50b is the length of the joint portion 50b in the Z-axis direction (the length in the direction orthogonal to the thickness direction of the joint portion 50b). The width L4 of the non-joint portion 51a is the length in the direction corresponding to the width L3 of the joint portion 50a shown in FIG. 2AB in a cross section orthogonal to the extending direction of the non-joint portion 51a shown in FIG. 2AA. Also, the width L4 of the non-joint portion 51b is the length in the direction corresponding to the width L3 of the joint portion 50b shown in FIG. 2AB in a cross section orthogonal to the extending direction of the non-joint portion 51b shown in FIG. 2AA.

[0071] The ratio L3 / L4 of these lengths may be, for example, 1 < L3 / L4 ≤ 5, or may be, for example, 1 < L3 / L4 ≤ 3. By pressing the joint portion 50a and the joint portion 50b so that the value of L3 / L4 falls within the above range, the bonding strength between the joint portion 50a and the joint portion 50b and the first connection pieces 41a and 41b can be improved. Also, the bonding area between the joint portion 50a and the joint portion 50b and the first connection pieces 41a and 41b can be increased, and the bonding stability between them can be improved.

[0072] The thickness L5 (FIG. 4) of the first connection pieces 41a and 41b may be larger than the thickness L1 of the joint portion 50a and the joint portion 50b. The ratio L5 / L1 of these lengths is, for example, 2 ≤ L5 / L1 ≤ 20. In this case, the thickness of the first connection pieces 41a and 41b becomes relatively large. Therefore, it is possible to more surely secure the physical strength of the first connection pieces 41a and 41b, and the bonding stability between the joint portion 50a and the joint portion 50b and the first connection pieces 41a and 41b can be improved.

[0073] Note that the thickness L5 of the first connection piece 41a is the length of the first connection piece 41a in the Y-axis direction (the direction orthogonal to the first surface 401). Also, the thickness L5 of the first connection piece 41b is the length of the first connection piece 41b in the Y-axis direction (the direction orthogonal to the first surface 401).

[0074] The width L6 (Figure 4) of the first connecting wire piece 41a and the first connecting wire piece 41b may be greater than the width L3 of the joint portion 50a and the joint portion 50b. In this case, the joint portion 50a and the joint portion 50b are less likely to protrude outward in the width direction of the first connecting wire piece 41a and the first connecting wire piece 41b, thereby improving the joint stability between them.

[0075] The width L6 of the first connecting wire piece 41a is the length of the first connecting wire piece 41a in the Z-axis direction (the direction in which the fifth surface 2e and the sixth surface 2f of the core 2 face each other). Similarly, the width L6 of the first connecting wire piece 41b is the length of the first connecting wire piece 41b in the Z-axis direction (the direction in which the fifth surface 2e and the sixth surface 2f of the core 2 face each other).

[0076] As shown in Figure 7A, a metal layer 60 is formed on the surface of terminal 4b. Similarly, a metal layer 60 is formed on the surface of terminal 4a. The metal layer 60 consists of a first metal layer 61 and a second metal layer 62 different from the first metal layer 61, and has a laminated structure. The first metal layers 61 and 62 are made of, for example, a plating film and are composed of metals or alloys thereof, such as Sn, Au, Ni, Pt, Ag, and Pd. For example, the first metal layer 61 contains Ni, and the second metal layer 62 contains Sn. Ni has the effect of preventing metal corrosion. Sn has the effect of improving the peel strength between the joints 50a and 50b when they are pressed against the first connecting piece 41a and the first connecting piece 41b, respectively. The metal layer 60 may also be formed by other thin-film methods such as sputtering. The thickness of the metal layer 60 may be 3 to 30 μm.

[0077] Between the joint 50b and the first connecting piece 41b, at least the first metal layer 61 of the first metal layer 61 and the second metal layer 62 is present. The first metal layer 61 connects the joint 50b and the first connecting piece 41b. The first metal layer 61, located between the joint 50b and the first connecting piece 41b, has the effect of improving the joint strength between them.

[0078] A second metal layer 62 is present at the Z-axis (width direction) end of the joint 50b, and this second metal layer 62 covers at least a portion of the Z-axis end of the joint 50b. Hereinafter, the second metal layer 62 covering at least a portion of the Z-axis end of the joint 50b will be referred to as the "adhesion portion 620". The adhesion portion 620 is obtained, for example, when the joint 50b and the first connecting wire piece 41b are joined by thermocompression bonding.

[0079] In other words, the attachment portion 620 is obtained when the joint portion 50b and the first connecting wire piece 41b are joined, for example, by the second metal layer 62 between them being pushed toward the Z-axis end of the joint portion 50b. Alternatively, after joining the joint portion 50b to the first connecting wire piece 41b, a separate process may be performed to form the attachment portion 620 at the Z-axis end of the joint portion 50b.

[0080] The thickness of the attachment portion 620 increases along the Z-axis direction as it approaches the joint portion 50b. The attachment portion 620 has the effect of improving the joint strength between the joint portion 50b and the first connecting wire piece 41b. A portion of the attachment portion 620 may be attached to the surface 53b of the joint portion 50b.

[0081] From the viewpoint of improving the joint strength between the joint portion 50b and the first connecting piece 41b, the thickness (maximum thickness or average thickness) of the second metal layer 62 on the first surface 401 of the first connecting piece 41b may be greater than the thickness (maximum thickness or average thickness) of the second metal layer 62 on the second surface 402.

[0082] A portion of the core 2 (such as magnetic particles) may be embedded inside the attachment portion 620. In this case, the volume of the core 2 arranged around the Z-axis end of the joint portion 50b increases, which can improve the inductance characteristics of the coil device 1.

[0083] The first surface 401 of the first connecting wire piece 41b joined to the joint 50b has a recess 403. The recess 403 is located within the joining area of ​​the first surface 401 facing the joining surface 52b. The recess 403 is curved to conform to the shape of the joining surface 52b facing the first surface 401.

[0084] The recess 403 is obtained, for example, by pressing the joint portion 50b against the first surface 401 with a jig and applying pressure during thermocompression bonding. At this time, as shown in Figure 7D, the recess 403 is formed on the first surface 401, and the first connecting wire piece 41b may also be curved. The presence of the recess 403 on the first surface 401 at the position of the joint portion 50b increases the bonding area between the joint portion 50b and the first connecting wire piece 41b, thereby improving the bonding strength between them.

[0085] In the YZ section, the joint 50b has an arc shape. Each end 55b of the joint 50b in the Z-axis direction is bent in a direction away from the first surface 401 of the first connecting piece 41b (towards the positive Y-axis direction). In addition, the central part of the joint 50b in the Z-axis direction is concave toward the second surface 402 of the first connecting piece 40b. As a result, the joining area between the joint 50b and the first connecting piece 41b is increased, and the joint strength between them can be improved.

[0086] As shown in Figures 7B and 7C, irregularities 54 are formed on the surface 53b of the joint 50b (the surface located on the opposite side in the Y-axis direction from the joint surface 52b shown in Figure 7A). Similarly, irregularities 54 are formed on the surface of the joint 50a. The irregularities 54 may be formed all over the surface 53b, or they may be formed locally.

[0087] Because irregularities 54 are formed on the surface 53b of the joint 50b, the surface roughness (arithmetic mean height) of the surface 53b of the joint 50b is greater than the surface roughness (arithmetic mean height) of the surface of the non-jointed portion 51b (Figure 2A). Also, the area of ​​the surface 53b of the joint 50b is greater than the area of ​​the surface of the non-jointed portion 51b (Figure 2A). Therefore, the core 2 adheres easily to the surface 53b of the joint 50b, thereby improving the bonding strength between the joint 50b and the core 2.

[0088] The difference in surface roughness between the surface 53b of the joint 50b and the surface roughness of the non-jointed portion 51b (Figure 2A) was confirmed by cutting (and further destroying by heat) the core 2 surrounding the joint 50b with a cutting tool, and then observing the exposed joint 50b with a laser microscope, or by cross-sectional observation with a scanning electron microscope.

[0089] Next, the manufacturing method of the coil device 1 will be described with reference to Figures 8A to 8D, etc. First, a conductive plate such as a metal plate is punched out into the shape shown in Figure 8A to form a frame 7 equipped with terminals 4a and 4b. Note that the frame 7 has terminals 4a and 4b formed on it in a state where the first connecting portion 45a and the first connecting portion 45b and the external electrode portion 47a and the external electrode portion 47b are not bent (see Figure 4).

[0090] A metal layer 60 (Figure 7A) having a first metal layer 61 and a second metal layer 62 may be formed on the surfaces of terminals 4a and 4b. The metal layer 60 can be formed, for example, by plating the surfaces of terminals 4a and 4b.

[0091] Next, as shown in Figure 8B, the coil 3 is placed between the connecting section 40a and the connecting section 40b. Then, for example, the extending end of the lead section 5a is joined to the first connecting piece 41a of the terminal 4a by thermocompression. Similarly, the extending end of the lead section 5b is joined to the first connecting piece 41b of the terminal 4b. Note that the insulating coating on the extending ends of the lead sections 5a and 5b may be removed beforehand.

[0092] During heat-sealing, the ends of the leading portions 5a and 5b in the extending direction are pressed against the first surface 401 of the first connecting wire pieces 41a and 41b using a jig and pressurized. As a result, the ends of the leading portions 5a and 5b in the extending direction are crushed, forming joint portions 50a and 50b having a substantially flattened shape. The joint portions 50a and 50b are arranged substantially parallel to the winding axis of the coil 3.

[0093] Next, terminal 4a is cut along cutting line C1, and terminal 4b is cut along cutting line C2 to form the assembly of coil 3 and terminals 4a and 4b shown in Figure 8C.

[0094] Next, the assembly shown in Figure 8C is placed in the mold, and the magnetic material (a composite magnetic material with thermoplastic resin or thermosetting resin as a binder) that constitutes the core 2 (Figure 2A) is filled into the inside of the mold. Then, the coil 3, along with the joint sections 40a and 40b to which the drawer sections 5a and 5b are joined, is covered with the magnetic material and compression molded. As a result, a molded body in which the coil 3 is embedded together with the joint sections 40a and 40b is obtained, as shown in Figure 8D.

[0095] Next, the first connecting portions 45a and 45b, and the external electrode portions 47a and 47b, which protrude from the outside of the molded body, are bent in the directions indicated by arrows B1 and B2. Then, the first connecting portion 45a is placed on the third surface 2c of the core 2 shown in Figure 2A, and the external electrode portion 47a is placed on the fifth surface 2e. Also, the first connecting portion 45b is placed on the fourth surface 2d of the core 2, and the external electrode portion 47b is placed on the fifth surface 2e. In this way, the coil device 1 can be obtained.

[0096] In the coil device 1 of this embodiment, as shown in Figure 2A, the connecting wire sections 40a and 40b are arranged substantially parallel to the winding axis of the coil 3. Therefore, the overhang of the magnetic flux from the connecting wire sections 40a and 40b into the magnetic flux path is reduced, and the overlap between the connecting wire sections 40a and 40b and the magnetic flux path is suppressed. As a result, the flow of magnetic flux is less likely to be obstructed by the connecting wire sections 40a and 40b, and the inductance characteristics of the coil device 1 can be improved.

[0097] Furthermore, the thickness L1 of the joint portion 50a and joint portion 50b is smaller than the thickness L2 of the non-joint portion 51a and non-joint portion 51b. As a result, the joint portion 50a and joint portion 50b are compressed in the thickness direction, making it possible to compactly join the joint portion 50a and joint portion 50b to the first connecting wire piece 41a and first connecting wire piece 41b. Consequently, the volume of core 2 that can be placed around the joint portion 50a and joint portion 50b is increased, and the inductance characteristics of the coil device 1 can be improved.

[0098] Second Embodiment The coil device 1A of the second embodiment shown in Figure 9 has the same configuration as the coil device 1 of the first embodiment, except for the points described below. In Figure 9, the same reference numerals are used for components that overlap with the coil device 1 of the first embodiment, and their detailed descriptions are omitted.

[0099] As shown in Figure 9, coil device 1A differs from coil device 1 in the first embodiment (Figure 2A) in that it has terminals 4aA and terminal 4bA. As shown in Figure 10, terminals 4aA and terminal 4bA do not have second connecting wire pieces 42a and 42b (Figure 4). In addition, along with the second connecting wire pieces 42a and 42b, a portion of the intermediate section 43a and intermediate section 43b is omitted from terminals 4a and 4b. On the other hand, terminals 4a and 4b have grooves 48a and 48b.

[0100] Grooves 48a and 48b are formed in the second connecting portion 46a and 46b, respectively, and extend along the Y-axis direction. A second connecting portion 46a_1 is formed on one side of groove 48a in the X-axis direction, and a second connecting portion 46a_2 is formed on the other side of groove 48a in the X-axis direction. That is, the second connecting portion 46a is divided into a second connecting portion 46a_1 and a second connecting portion 46a_2. The second connecting portion 46b has a similar configuration to the second connecting portion 46a and is divided into a second connecting portion 46b_1 and a second connecting portion 46b_2. By forming grooves 48a and 48b in the second connecting portion 46a and 46b, respectively, it becomes easier to bend the first connecting piece 41a and the first connecting piece 41b at the positions of the second connecting portion 46a and the second connecting portion 46b.

[0101] In this embodiment, the same effects as in the first embodiment can be obtained. In addition, in this embodiment, the second connecting wire piece 42a and the second connecting wire piece 42b are omitted from terminals 4a and 4b, thus simplifying the configuration of terminals 4a and 4b and facilitating the manufacture of the coil device 1.

[0102] Third Embodiment The coil device 1B of the third embodiment shown in Figure 11 has the same configuration as the coil device 1 of the first embodiment, except for the points described below. In Figure 11, the same reference numerals are used for components that overlap with the coil device 1 of the first embodiment, and their detailed descriptions are omitted.

[0103] Coil device 1B differs from coil device 1 in the first embodiment (Figure 2A) in that it has a coil 3B. Coil 3B is formed from flat-wound flat wire. Coil 3B may also be formed from edge-wound flat wire. In the YZ cross section, joint portions 50a and 50b have a substantially flattened shape (plate-like). Similarly, non-joint portions 51a and 51b also have a substantially flattened shape.

[0104] In this embodiment as well, the same effects as in the first embodiment can be obtained. In addition, in this embodiment, the wide surface of the rectangular wire constitutes the joint surface of joint 50a and joint 50b. Therefore, the joint area between joint 50a and joint 50b and the first connecting wire piece 41a and first connecting wire piece 41b can be increased, and the joint stability between them can be improved.

[0105] Furthermore, this application is not limited to the embodiments described above, and can be modified in various ways within the scope of this application.

[0106] In the above embodiments, examples of applying the coil device 1 to an inductor were shown, but the coil device 1 may be an electronic component other than an inductor.

[0107] In the first embodiment described above, as shown in Figures 2AB and 4, the width L3 of the joint 50a and joint 50b was smaller than the width L6 of the first connecting wire piece 41a and first connecting wire piece 41b (Figure 4). However, the width L3 may be equal to or greater than the width L6. The same applies to the second and third embodiments described above.

[0108] In the first embodiment described above, as shown in Figure 2A, the joints 50a and 50b were joined to the first surface 401 of the first connecting piece 41a and the first connecting piece 41b, but they may also be joined to the second surface 402. The same applies to the second and third embodiments described above.

[0109] In the first embodiment described above, as shown in Figure 5A, the mounting parts 47a and 47b were arranged on the fifth surface 2e of the core 2. However, as shown in Figure 5B, the mounting parts 47a and 47b may be arranged on the sixth surface 2f of the core 2. The same applies to the second and third embodiments described above.

[0110] In the first embodiment described above, the joint 50a and the joint 50b may be joined to the first connecting piece 41a and the first connecting piece 41b by a method other than thermocompression bonding (for example, laser welding). [Explanation of Symbols]

[0111] 1, 1A, 1B... Coil device 2... Core 3,3B...coil 30... Volume 30 4a, 4b, 4aA, 4bA… terminals 40a, 40b…Connection section 401...Side 1 402…Second side 403…recess 41a, 41b...1st connection piece 42a, 42b…Second connection piece 43a, 43b…middle part 44a, 44b... curved section 45a, 45b... First connection section 46a, 46b, 46a_1, 46b_1, 46a_2, 46b_2… Second connection section 47a, 47b…Implementation section 48a, 48b…Groove 5a,5b…Drawer part 50a,50b…Joint part 51a, 51b…Non-joint part 52b...joint surface 53b…Surface 54…Unevenness 6...Metal layer 61...first metal layer 62…Second metal layer 620...Attachment part 7...frames

Claims

1. The core and A coil having a winding portion disposed inside the core and a lead portion drawn out from the winding portion, It has a terminal having a connecting wire portion that is joined to the lead portion and arranged inside the core, The connecting portion, which has a flat plate shape, is arranged substantially parallel to the winding axis of the coil. The core has a corner where a plurality of surfaces, arranged substantially parallel to the winding axis of the coil, intersect. The aforementioned corner portion has a first corner portion and a second corner portion located on the opposite side of the first corner portion, along a direction substantially perpendicular to the winding axis of the coil. The flat-plate-shaped connecting portion comprises a first connecting piece to which the lead portion is joined, and a second connecting piece located on the opposite side from the first connecting piece, along a direction substantially perpendicular to the winding axis of the coil. The first connecting piece and the second connecting piece are formed along the first axial direction, The first connecting piece is positioned at the first corner, and the second connecting piece is positioned at the second corner. The joint of the lead-out portion is joined to one end of the first connecting wire piece in the first axial direction, rather than to the center in the first axial direction of the coil device.

2. The coil device according to claim 1, wherein the connecting portion is arranged substantially parallel to one or the other surface of the core that is facing the winding shaft in a direction substantially perpendicular to the winding shaft.

3. A portion of the terminal is exposed from one or the other side of the core. The coil device according to claim 2, wherein the connecting portion is arranged substantially parallel to one or the other surface of the core.

4. The coil device according to any one of claims 1 to 3, wherein, with respect to the winding axis direction of the coil, one end of the connecting portion is positioned at approximately the same position as one end of the coil.

5. The coil device according to any one of claims 1 to 3, wherein the lead portion is joined to the first surface of the connecting portion facing the coil.

6. The coil device according to any one of claims 1 to 3, wherein the lead portion is biased by the elastic force of the lead portion so as to press against the connecting portion.

7. The aforementioned lead-out portion has a joint portion joined to the aforementioned connecting portion, The coil consists of flat wire wound in a flatwise manner. The coil device according to any one of claims 1 to 3, wherein the wide surface of the rectangular wire constitutes the joint surface with the connecting wire portion of the joint.

8. The aforementioned lead portion has a joint portion joined to the connecting portion and a non-joint portion separated from the joint portion. The coil device according to any one of claims 1 to 3, wherein the first thickness of the joint is smaller than the second thickness of the non-jointed portion.

9. The coil device according to claim 8, wherein the third thickness of the joint portion is greater than the first thickness of the joint portion.

10. The coil device according to claim 8, wherein the first width of the joint is greater than the second width of the non-jointed portion.

11. The coil device according to claim 10, wherein the third width of the connecting portion is greater than the first width of the joint portion.

12. The terminal has a first terminal and a second terminal, The aforementioned connecting portion has a first connecting portion provided at the first terminal and a second connecting portion provided at the second terminal. The aforementioned drawer section has a first drawer section and a second drawer section. The coil device according to any one of claims 1 to 3, wherein the first lead portion and the second lead portion are joined to the first connecting portion and the second connecting portion, respectively, on the same side of the core in the first direction.

13. The coil device according to claim 12, wherein the first lead portion and the second lead portion are joined to one end of the first joint portion in the first direction and one end of the second joint portion in the first direction, respectively.

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