Patent Grant
8779878
1. Field of the Invention
The present invention relates to a magnetic component including a magnetic core that includes a flange portion at each of opposite end portions of a winding shaft portion around which a conductive wire is wound, and a conductive terminal that includes a wire splicing surface for conductive wire connection, and a method for manufacturing such magnetic component.
2. Description of the Related Art
Conventionally, magnetic components such as disclosed in Japanese Laid-Open Patent Publication No. 2009-290093(A) are known. An example of this type of magnetic component is illustrated in
As illustrated in
The terminals 130A and 130B each include an electrode portion 131 extending along a lower surface of the lower flange portion 125, and a wire splicing portion 133 extending from an end portion of the electrode portion 131. The electrode portion 131 is attached to the lower flange portion 125 so as to be in contact with the lower surface of the lower flange portion 125. The wire splicing portion 133 includes a part extending upward in the Figure (direction toward the upper flange portion 123), which is flexed at an angle of 90 degrees from the end portion of the electrode portion 131 (hereinafter this part is referred to as “erected portion”), and a part extending laterally (direction perpendicular to an axis of the winding shaft portion 121), which is further flexed at an angle of 90 degrees from an upper end portion of the erected portion (hereinafter this part is referred to as “laterally-flexed portion”), and an upper surface of the laterally-flexed portion includes a wire splicing surface 135 for conductive wire connection. These terminals 130A and 130B are each formed by flexing a metal plate material via, e.g., press working.
The coil 140 includes a conductive wire 141 wound around the winding shaft portion 121. Respective end portions 141a and 141b of the conductive wire 141 are connected to the respective wire splicing surfaces 135 of the terminals 130A and 130B via, e.g., thermal compression bonding or resistance welding.
As illustrated in the Figure, the welding jig 170 includes projection portions 171A and 171B. These projection portions 171A and 171B are provided to support the respective wire splicing surfaces 135 of the terminals 130A and 130B (the above-described laterally-flexed portions) from the lower side, which are pressed from the upper side in the Figure by a welding electrode 180, when connecting the respective end portions 141a and 141b of the conductive wire 141 to the respective wire splicing surfaces 135 of the terminals 130A and 130B via thermal compression bonding.
In order to connect the respective end portions 141a and 141b of the conductive wire 141 to the respective wire splicing surfaces 135 of the terminals 130A and 130B of the above-described conventional magnetic component 110 with good precision via thermal compression bonding, it is necessary that welding electrode 180 sufficiently press the respective wire splicing surfaces 135 of the terminals 130A and 130B while crushing the respective end portions 141a and 141b of the conductive wire 141 to a predetermined extent. In particular, where the magnetic component 110 is downsized so as to have external dimensions of around several millimeters, each wire splicing surface 135 is inevitably downsized, resulting in reduction in the area of the part to be welded, and thus, provision of a proper extent of crushing of the respective end portions 141a and 141b of the conductive wire 141 during thermal compression bonding is important for favorable connection of the conductive wire 141.
However, since the terminals 130A and 130B of the conventional magnetic component 110 are each formed by flexing a metal plate via, e.g., press working, large variations easily occur in a dimension in the height direction of the wire splicing portions 133. This is because not only errors caused by processing using, e.g., a pressing machine but also a tolerance in thickness of the metal plate affect the dimension in the height direction of the wire splicing portions 133.
Where large variations occur in the dimension in the height of the wire splicing portions 133, a fixed distance between a lower surface of the welding electrode 180 and each wire splicing surface 135 during thermal compression bonding cannot be maintained, making is difficult to provide a proper extent of crushing of the respective end portions 141a and 141b of the conductive wire 141, which may cause various types of failures. For example, if the extent of crushing is reduced, it may be impossible to provide sufficient connection strength, and conversely, if the extent of crushing is overly increased, the conductive wire 140 may be disconnected.
Also, a problem lies also in errors in dimension in the height direction of the projection portions 171A and 171B included in the welding jig 170. In other words, if the height of the projection portions 171A and 171B is smaller than a prescribed value, a distance ε between lower surfaces of the laterally-flexed portions of the terminals 130A and 130B and upper surfaces of the projection portions 171A and 171B is large. If the distances is excessively large, the laterally-flexed portions of the terminals 130A and 130B are pressed by the welding electrode 180 and thereby bent downward during thermal compression bonding, whereby the extent of crushing of the respective end portions 141a and 141b of the conductive wire 141 becomes small, which may result in impossibility to provide sufficient connection strength. Conversely, if the height of the projection portions 171A and 171B is larger than the prescribed value, a position in height direction of the wire splicing surfaces 135 is raised, whereby the extent of crushing of the respective end portions 141a and 141b of the conductive wire 141 during thermal compression bonding becomes too large, which may cause disconnection of the conductive wire 140.
The present invention has been made in view of the aforementioned circumstances, and an object of the present invention is to provide a magnetic component enabling an end portion of a conductive wire wound around a winding shaft portion of a magnetic core to be stably and favorably connected to a wire splicing surface of a terminal, and a method for manufacturing such magnetic component.
In order to achieve the above object, a magnetic component according to the present invention has the following characteristics.
In other words, a magnetic component according to the present invention includes: a magnetic core including an upper flange portion on one end side of a winding shaft portion and a lower flange portion on another end side of the winding shaft portion; a conductive terminal attached to the lower flange portion; and a conductive wire wound around the winding shaft portion, wherein the terminal includes an electrode portion extending along a lower surface of the lower flange portion and including an end portion projecting outward relative to an outer periphery of the lower flange portion, and a columnar wire splicing portion erected from the end portion of the electrode portion; and wherein an upper end surface of the wire splicing portion includes a wire splicing surface for conductive wire connection, and an end portion of the conductive wire is connected to the wire splicing surface.
In the magnetic component according to the present invention, the conductive wire can be a coated conductive wire including a core wire and an insulating coating covering the core wire.
Also, it is preferable that the magnetic core be a ferrite core including an Ni—Zn ferrite or an Mn—Zn ferrite.
The terminal according to the present invention may include an electrode portion extending along an outer end surface of one of the flange portions and including an end portion projecting outward relative to an outer periphery of the one of the flange portions, and a triangular columnar wire splicing portion erected from the end portion of the electrode portion.
Further, it is preferable that the wire splicing surface, which is an upper end surface of the erected part of the wire splicing portion, is arranged perpendicular to a side surface of the erected part.
In the magnetic component according to the present invention, a height H of the wire splicing portion may be larger than a length T−R obtained by subtracting a length R corresponding to a radius of the conductive wire wound around the winding shaft portion from a thickness T of the one of the flange portions.
Further, the height H of the wire splicing portion may be smaller than a length T+W−D obtained by subtracting a length D corresponding to a diameter of the conductive wire wound around the winding shaft portion from a value obtained by adding a width W of the winding shaft portion to the thickness T.
Still further, the height H of the wire splicing portion may be smaller than a length T+D obtained by adding a length D corresponding to a diameter of the conductive wire wound around the winding shaft portion to the thickness T.
In the magnetic component according to the present invention, the conductive wire may have a diameter of 0.02 to 0.30 mm.
Further, the conductive wire may have a diameter of 0.02 to 0.10 mm.
In the magnetic component according to the present invention, a round surface is provided in a boundary part between a side surface of the wire splicing portion and the wire splicing surface.
The boundary part between a side surface of the wire splicing portion and the wire splicing surface may be a chamfered surface.
It is preferable that a side surface of the wire splicing portion of the terminal includes a curved surface.
Also, a method for manufacturing a magnetic component according to the present invention includes connecting the end portion of the conductive wire of the aforementioned magnetic component according to the present invention to the wire splicing surface via thermal compression bonding or resistance welding.
The “columnar” in the “columnar wire splicing portion” in the above basically refers to a shape in which a gauge (cross-sectional area) of a wire splicing portion is constant over the entire length in the height direction of the wire splicing portion, but is not intended to exclude a shape in which the gauge of the wire splicing portion varies.
A magnetic component and a method for manufacturing a magnetic component according to an embodiment of the present invention will be described in detail below with reference to the drawings.
<Configuration of Magnetic Component>
As illustrated in
The upper flange portion 23 and the lower flange portion 25 of the magnetic core 20 each have a same size and a same shape (octagonal shape), and the winding shaft portion 21 has an octagonal columnar shape. Also, the magnetic core 20 includes a ferrite core including a Ni—Zn ferrite or an Mn—Zn ferrite. Formation of the magnetic core 20 using an Ni—Zn ferrite or an Mn—Zn ferrite as described above enables the magnetic core 20 to be downsized compared to a case where the magnetic core 20 includes an Fe—Si alloy or an Fe—Ni alloy.
The terminals 30A and 30B each include an electrode portion 31 extending along a lower surface of the lower flange portion 25 and including an end portion projecting outward relative to an outer periphery of the lower flange portion 25, and a triangular columnar wire splicing portion 33 erected from the end portion of the electrode portion 31, and an upper end surface of the wire splicing portion 33 includes a wire splicing surface 35 for conductive wire connection. In other words, respective end portions 41a and 41b of the conductive wire 41 wound around the winding shaft portion 21 of the magnetic core 20 is connected to the wire splicing surface 35 via thermal compression bonding or resistance welding.
Furthermore, in the magnetic component 10 according to the present embodiment, as illustrated in
Furthermore, a gauge (cross-sectional area in a horizontal direction) of the wire splicing portion 33 is formed to be constant in the height direction of the wire splicing portion 33, and as illustrated in
Furthermore, a dimension H in the height direction (height from an upper surface of the electrode portion 31) (see
More specifically, the dimension H in the height direction of the wire splicing portion 33 is set to be larger than the dimension obtained by subtracting the length corresponding to the radius of the conductive wire 41 of the magnetic core 20 wound around the winding shaft portion 21 from the dimension T in the height direction of the lower flange portion 25, and also to be smaller than a dimension obtained by subtracting a length corresponding to a diameter of the conductive wire 41 wound around the winding shaft portion 21 of the magnetic core 20 from a dimension obtained by adding a dimension (width) W (see
In particular, it is preferable that the dimension H in the height direction of the wire splicing portion 33 be set to be larger than the dimension obtained by subtracting the length corresponding to the radius of the conductive wire 41 wound around the winding shaft portion 21 of the magnetic core 20 from the dimension T in the height direction of the lower flange portion 25, and also to be smaller than a dimension obtained by adding the length corresponding to the diameter of the conductive wire 41 wound around the winding shaft portion 21 of the magnetic core 20 to the dimension T.
As a result of determining the dimension H in the height direction of the wire splicing portion 33 as described above, the possibility of disconnection of the conductive wire 41 when connecting the respective end portions of the conductive wire 41 wound around the winding shaft portion 21 of the magnetic core 20 to the wire splicing surface 35 via, e.g., thermal compression bonding can be lowered.
The coil 40 includes the conductive wire 41 wound around the winding shaft portion 21 of the magnetic core 20. The conductive wire 41 includes a coated conductive wire including a core wire (not illustrated) and an insulating coating covering the core wire (not illustrated), and the respective end portions 41a and 41b of the conductive wire 41 are connected to the wire splicing surfaces 35 of the terminals 30A and 30B via, e.g., thermal compression bonding or resistance welding.
For the conductive wire 41, for example, one having an arbitrary gauge from among conductive wires having a diameter ranging from 0.02 to 0.30 mm can be used according to the size of the magnetic component 10. For example, an ultrafine wire having a diameter of around 0.02 to 0.05 mm or a fine wire having a diameter of around 0.05 to 0.10 mm can be used. Also, a wire having a diameter that is or exceeds around 0.10 to 0.20 mm can be used.
<Method for Manufacturing Magnetic Component>
As illustrated in
(1) The conductive wire 41 is wound around the winding shaft portion 21 of the magnetic core 20 and the magnetic component 10 with the respective end portions 41a and 41b of the conductive wire 41 mounted on the wire splicing surfaces 35 of the terminals 30A and 30B is set on a welding jig 70. Since the wire splicing portions 33 of the terminals 30A and 30B each have a columnar shape, the welding jig 70 has a planar shape so as to wholly support the terminals 30A and 30B, and has no projection portions 171A and 171B (see
(2) A distance of movement of the welding electrode 80 in the vertical direction in the Figure is adjusted. The adjustment of the distance of movement is made so that an extent of crushing of the end portions 41a and 41b becomes proper when the respective end portions 41a and 41b of the conductive wire 41 on the wire splicing surfaces 35 are pressed by the welding electrode 80, in consideration of the position in the height direction of the wire splicing surfaces 35 of the terminals 30A and 3013 (which is calculated based on a designed dimension in the height direction of the wire splicing portions 33) and the diameter of the conductive wire 41.
(3) The welding electrode 80 is lowered, and the respective end portions 41a and 41b of the conductive wire 41 on the wire splicing surfaces 35 are pressed and crushed by a lower surface of the welding electrode 80 to weld the respective end portions 41a and 41b to the wire splicing surfaces 35.
The position in the height direction of the wire splicing surfaces 35 of the magnetic component 10 has only a small variation from a designed value because the wire splicing portions 33 have a columnar shape. Thus, a proper extent of crushing of respective end portions 41a and 41b of a conductive wire 41 during thermal compression bonding can be provided to each of magnetic components 10 having same design specifications, enabling the respective end portions 41a and 41b of the conductive wire 41 to be connected to wire splicing surfaces 35 stably and favorably.
<Modification of Terminals>
In the terminal 30C illustrated in
Where the round surface 36 or the chamfered surface 37 is provided as described above, the area of the wire splicing surface 35 is narrowed compared to that of the terminals 30A and 30B described above, but the possibility of disconnection of a conductive wire when connecting an end portion of the conductive wire to the wire splicing surface 35 via, e.g., thermal compression bonding can be decreased.
In the terminal 30E illustrated in
In the terminal 30G illustrated in
<Other Modifications>
Although an embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and various modifications are possible.
For example, although the upper flange portion 23 and the lower flange portion 25 of the magnetic core 20 each have an octagonal shape in the above embodiment, the shape of the upper flange portion 23 and the lower flange portion 25 can be varied to various shapes, e.g., a round shape or an oval shape, or another polygonal shape such as a pentagonal shape or a hexagonal shape. Also, although in the above embodiment, the upper flange portion 23 and the lower flange portion 25 are identical to each other in size and shape, flange portions that are not identical to each other and are different from each other in shape and size can be used. The shape of the winding shaft portion 21 can be changed to an arbitrary shape such as a round columnar shape or an oval columnar shape.
Although in the above embodiment, the magnetic core 20 includes a Ni—Zn ferrite or a Mn—Zn ferrite, the magnetic core 20 may be formed using another magnetic material such as a Fe—Si alloy or a Fe—Ni alloy.
Also, although in the above embodiment, thermal compression bonding and resistance welding are indicated as examples of a method for connecting an end portion of a conductive wire to a wire splicing surface of a terminal, an end portion of a conductive wire may be connected by another method such as soldering.
In the magnetic component according to the present invention, a terminal includes a columnar wire splicing portion, and an upper end surface of the wire splicing portion is configured as a wire splicing surface for conductive wire connection, enabling provision of the following operation and effects.
In other words, when connecting an end portion of a conductive wire wound around a winding shaft portion of a magnetic core to a wire splicing surface of a columnar wire splicing portion, the columnar wire splicing portion can bear a force imposed on the wire splicing surface by itself, eliminating the need to form a projection portion for supporting the wire splicing surface in a welding jig. Thus, as opposed to the conventional technique, there are no adverse effects of errors in dimension of the projection portion on the precision of connection of the conductive wire.
Also, the columnar wire splicing portion can be formed by, e.g., cutting a metal member, enabling variation of a position in the height direction of the wire splicing surface to be reduced compared to those of terminals including a wire splicing portion formed by flexing a metal plate member as in the conventional technique.
Accordingly, for example, when connecting an end portion of a conductive wire to a wire splicing surface via thermal compression bonding, a substantially-fixed distance between a lower surface of a welding electrode and the wire splicing surface can be maintained, making it easy to provide a proper extent of crushing of the end portion of the conductive wire during the thermal compression bonding, and thus, enabling the end portion of the conductive wire to be stably and favorably connected to the wire splicing surface.
Also, a method for manufacturing a magnetic component according to the present invention enables an end portion of a conductive wire wound around a winding shaft portion of a magnetic core to be stably and favorably connected to a wire splicing surface of a terminal via thermal compression bonding or resistance welding.
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