The present invention relates to a coil component and, more particularly, to a coil component using a drum-shaped core.
A coil component using a drum-shaped core is widely used in electronic devices such as smartphones for the reason that it is smaller in size than a coil component using a toroidal-shaped core and can be mounted on the surface of a circuit board. The drum-shaped core has a winding core part around which wires are wound and a pair of flange parts provided at both axial end portions of the winding core part, and end portions of respective wires are connected respectively to a plurality of terminal electrodes provided on each of the flange parts. While coil winding work around the winding core part and connecting work between the wire and the terminal electrode are achieved usually by using an automatic winding machine, it is not easy to accurately connect the wires and terminal electrodes due to recent miniaturization of the coil component.
In this regard, JP 2011-119379 A proposes a method that forms a V-cut in the vicinity of the terminal electrode and inserts the wire into the V-cut so as to stabilize the positional relationship between the terminal electrode and the wire.
However, as described in JP 2017-17288 A, in a coil component having many terminal electrodes on the flange part, a terminal electrode positioned at the end portion of the flange part may be distanced from the winding core part. In this case, even when the V-cut is formed in the vicinity of the terminal electrode, the wire needs to be bent at an acute angle in the V-cut, applying stress to the wire. Particularly, in a small-sized coil component, a wire having a small diameter is used, so that application of excessive stress may cause disconnection in the worst case.
It is therefore an object of the present invention to provide a coil component capable of stabilizing the positional relationship between the terminal electrode and the wire even when the terminal electrode is distanced from the winding core part.
A coil component according to the present invention includes: a core including a winding core part extending in a first direction, a first flange part provided at one axial end of the winding core part, and a second flange part provided at other axial end of the winding core part; a plurality of terminal electrodes provided on the first flange part so as to be arranged in a second direction perpendicular to the first direction; a plurality of terminal electrodes provided on the second flange part so as to be arranged in the second direction; and a plurality of wires wound around the winding core part such that one end of each wire is connected to any one of the plurality of terminal electrodes provided on the first flange part and other end of each wire is connected to any one of the plurality of terminal electrodes provided on the second flange part. The plurality of terminal electrodes provided on the first flange part include a first terminal electrode whose position in the second direction does not overlap the winding core part, and the plurality of terminal electrodes provided on the second flange part include a second terminal electrode whose position in the second direction does not overlap the winding core part. The plurality of wires include first and second wires connected to the first and second terminal electrodes, respectively. Each of the first and second wires includes a wound part wound around the winding core part and drawn part drawn from the wound part, running across the winding core part in a third direction perpendicular to the first and second directions and connected to one of the first and second terminal electrodes. The core has a first positioning part that positions the drawn part of the first wire in the second direction and a second positioning part that positions the drawn part of the second wire in the second direction.
According to the present invention, the core has the first and second positioning parts, whereby the positional relationship between a terminal electrode distanced from the winding core part and the wire can be stabilized.
In the present invention, the first positioning part may be a groove or a step provided in the first flange part and extending in the third direction, and the second positioning part may be a groove or a step provided in the second flange part and extending in the third direction. With this configuration, the wire is bent more gently than when a V-cut is formed in the vicinity of the terminal electrode, making it possible to relieve stress applied to the wire.
In the present invention, the groove or step may have an inclined surface making the depth thereof in the first direction increase toward the first and second terminal electrodes. This can further relieve the stress applied to the wire.
In the present invention, the first positioning part may be formed over the entire length area of the first flange part in the third direction, and the second positioning part may be formed over the entire length area of the second flange part in the third direction. This facilitates production of the core using a die.
In the present invention, the first positioning part may have a length in the third direction shorter than the length of the first flange part in the third direction and have a shape in which the end portion thereof on the first terminal electrode side is opened, and the second positioning part may have a length in the third direction shorter than the length of the second flange part in the third direction and have a shape in which the end portion thereof on the second terminal electrode side is opened. With this configuration, the volume of the core can be ensured to thereby obtain high magnetic characteristics.
In the present invention, each of the first and second positioning parts partially overlaps the winding core part in the third direction. With this configuration, the wire is bent gently, so that the stress applied to the wire can be relieved.
In the present invention, the first and second flange parts may each include a first area whose position in the first direction overlaps the plurality of terminal electrodes and a second area positioned between the first area and the winding core part and whose position in the first direction does not overlap the plurality of terminal electrodes. A step may be formed between the end portions of the respective first and second areas in the third direction, making the second region be lower in position than the first area in the third direction. Both the first and second positioning parts may be formed in the second area. This can relieve the stress applied to the wire.
In the present invention, the first positioning part may be a projection provided on the first flange part, and the second positioning part may be a projection provided on the second flange part. With this configuration, it is possible to stabilize the positional relationship between a terminal electrode distanced from the winding core part and the wire without reducing the volume of the core.
As described above, according to the present invention, it is possible to stabilize the positional relationship between the terminal electrode and the wire even when the terminal electrode is distanced from the winding core part.
The above and other objects, features and advantages of this invention will become more apparent by reference to the following detailed description of the invention taken in conjunction with the accompanying drawings, wherein:
Preferred embodiments of the present invention will now be explained in detail with reference to the drawings.
The coil component 1 according to the first embodiment is a surface-mount type pulse transformer and has a drum-shaped core 10, a plate-like core 20 bonded to the core 10, and four wires W1 to W4 wound around a winding core part 13 of the core 10 as illustrated in
However, the coil component according to the present invention is not limited to the pulse transformer, but may be a transformer component of another type such as a balun transformer or a boosting transformer, or a filter component such as a common mode choke coil.
The cores 10 and 20 are each made of a magnetic material having comparatively high permeability, such as a sintered body of an Ni—Zn based ferrite or an Mn—Zn based ferrite. In general, a magnetic material having high permeability such as the Mn—Zn based ferrite is low in specific resistance and thus has conductivity.
The drum-shaped core 10 integrally has a rod-like winding core part 13 whose axis extends in the x-direction and first and second flange parts 11 and 12 provided at both ends of the winding core part 13 in the x-direction. The first flange part 11 has an inner surface 11i and an outer surface 11o which constitute the yz plane and a mounting surface 11b and a bonding surface 11t which constitute the xy plane. Similarly, the second flange part 12 has an inner surface 12i and an outer surface 12o which constitute the yz plane and a mounting surface 12b and a bonding surface 12t which constitute the xy plane.
The coil component 1 is a chip component surface-mounted on a printed circuit board when used and is mounted with the mounting surfaces 11b and 12b of the flange parts 11 and 12 facing the printed circuit board. The plate-like core 20 is fixed to the bonding surfaces 11t and 12t of the flange parts 11 and 12 with an adhesive. A closed magnetic loop is formed by the thus configured drum-shaped core 10 and plate-like core 20.
Four terminal electrodes 31 to 34 are arranged in the y-direction on the mounting surface 11b of the first flange part 11, and four terminal electrodes 35 to 38 are arranged in the y-direction on the mounting surface 12b of the second flange part 12. The terminal electrodes 31 to 34 may be formed over the mounting surface 11b and outer surface 11o, and the terminal electrodes 35 to 38 may be formed over the mounting surface 12b and outer surface 12o. Further, the terminal electrodes 31 to 38 may be formed not only on the mounting surfaces 11b and 12b, but also on their opposing bonding surfaces 11t and 12t. The terminal electrodes 31 to 38 may each be a conductive film applied to the corresponding flange part 11 or 12 or may each be a terminal fitting. Of the terminal electrodes 31 to 38, the terminal electrodes 31, 34, 35, and 38 each positioned at the end portion in the y-direction do not overlap the winding core part 13 in the y-direction; the remaining terminal electrodes 32, 33, 36, and 37 overlap the winding core part 13 in the y-direction.
As illustrated in
Although not particularly limited, the wire W1 is connected to the terminal electrodes 31 and 36, and the winding direction thereof is, for example, clockwise. The wire W2 is connected to the terminal electrodes 32 and 35, and the winding direction thereof is, for example, counterclockwise. The wire W3 is connected to the terminal electrodes 33 and 38, and the winding direction thereof is, for example, clockwise. The wire W4 is connected to the terminal electrodes 34 and 37, and the winding direction thereof is, for example, counterclockwise. With this configuration, for example, the terminal electrodes 31 and 32 can be used as the primary side input/output terminal of the pulse transformer, the terminal electrodes 37 and 38 can be used as the secondary side input/output terminal of the pulse transformer, the terminal electrodes 35 and can be used as the primary center tap of the pulse transformer, and the terminal electrodes 33 and 34 can be used as the secondary center tap of the pulse transformer. The terminal electrodes 35 and 36 constituting the primary center tap may be combined into a single terminal electrode. Similarly, the terminal electrodes 33 and 34 constituting the secondary center tap may be combined into a single terminal electrode.
In the coil component 1 according to the present embodiment, grooves 41 and 42 are formed in the inner surface 11i of the flange part 11, and grooves 43 and 44 are formed in the inner surface 12i of the second flange part 12. The grooves 41 and 42 are formed at substantially the same position in the y-direction as the terminal electrodes 31 and 34, respectively and each constitute a first positioning part for positioning a drawn part of the wire (W1 and W4) in the y-direction. Similarly, the grooves 43 and 44 are formed at substantially the same position in the y-direction as the terminal electrodes 35 and 38, respectively and each constitute a second positioning part for positioning a drawn part of the wire (W2 and W3) in the y-direction. The drawn parts of the wires W1 to W4 refer to portions drawn from the wound part of the wire wound around the winding core part 13, running across the winding core part 13 in the z-direction, and connected to the terminal electrodes 31, 34, 35, and 38, respectively.
In the present embodiment, the grooves 41 and 42 are formed over the entire length area of the flange part 11 in the z-direction, and the grooves 43 and 44 are formed over the entire length area of the flange part 12 in the z-direction. Thus, when the core 10 having the grooves 41 to 44 are produced using a die, the shape of the die can be simplified, and removal of the core 10 from the die can be facilitated.
As illustrated in
On the other hand, when the groove 41 does not exist as illustrated in
The above problem can be solved by bending the wire W1 in the vicinity of the terminal electrode 31 as illustrated in
On the other hand, in the present embodiment, the drawn part W1b of the wire W1 shifted in position in the y-direction is positioned in the y-direction by the inner wall surface 41a of the groove 41, so that, as described above, after being detached from the groove 41, the wire W1 can be drawn substantially straight in the x-direction with respect to the terminal electrode 31. This can prevent connection failure or defect in appearance and can relieve the stress applied to the wire W1.
Further, as illustrated in
The same applies to the other wires W2 to W4. That is, the wires W2, W3, and W4 are positioned by their corresponding grooves 43, 44, and 42, respectively and connected to their corresponding terminal electrodes 35, 38, and 34, respectively.
As described above, in the coil component 1 according to the present embodiment, the grooves 41 and 42 are formed in the inner surface 11i of the flange part 11, and the grooves 43 and 44 are formed in the inner surface 12i of the flange part 12. The wires W1 to W4 are positioned in the y-direction by their corresponding grooves 41 to 44, respectively, so that it is possible to stabilize the positional relationship between the terminal electrodes 31 to 38 and the wires W1 to W4 while relieving the stress applied to the wires W1 to W4. In addition, in the present embodiment, the grooves 41 and 42 are formed over the entire length area of the flange part 11 in the z-direction, and the grooves 43 and 44 are formed over the entire length area of the flange part 12 in the z-direction. Thus, when the core 10 having the grooves 41 to 44 are produced using a die, the shape of the die can be simplified, and removal of the core 10 from the die can be facilitated.
As illustrated in
In the present embodiment, one end portion of each of the grooves 41 to 44 in the z-direction is opened at the side of the mounting surface (11b, 12b), i.e., the side of the terminal electrode (31 to 38), while the other end portion thereof in the z-direction does not reach the bonding surface (11t, 12t) but is terminated halfway. While the specific length in the z-direction of each of the grooves 41 to 44 is not particularly limited, the stress applied to the wires W1 to W4 becomes smaller as the groove becomes deeper, whereas the volume of the core 10 is increased as the groove becomes shallower. In order to ensure a sufficient volume of the core 10 while effectively relieving the stress applied to the wires W1 to W4, the grooves 41 to 44 are preferably made shallow within a range that the grooves overlap the winding core part 13 in the z-direction.
As exemplified in the present embodiment, in the present invention, the grooves 41 to 44 each constituting the positioning part need not be formed over the entire length area of the flange part (11, 12) in the z-direction.
As illustrated in
The steps 51 to 54 are each a portion where the thickness in the x-direction is reduced at the end portion of the flange part (11, 12) in the y-direction and each equivalent to a shape illustrated in
As exemplified in the present embodiment, in the present invention, the positioning part need not be constituted by the groove (41 to 44), but may be constituted by the step (51 to 54).
As illustrated in
In the present embodiment, one end portion of each of the steps 51 to 54 in the z-direction is opened at the side of the mounting surface (11b, 12b), i.e., the side of the terminal electrode (31 to 38), while the other end portion thereof in the z-direction does not reach the bonding surface (11t, 12t) but is terminated halfway. While the specific length of each of the steps 51 to 54 is not particularly limited, the stress applied to the wires W1 to W4 becomes smaller as the step becomes deeper, whereas the volume of the core 10 is increased as the step becomes shallower. In order to ensure a sufficient volume of the core 10 while effectively relieving the stress applied to the wires W1 to W4, the steps 51 to 54 are preferably made shallow within a range that the steps overlap the winding core part 13 in the z-direction.
As exemplified in the present embodiment, in the present invention, the steps 51 to 54 each constituting the positioning part need not be formed over the entire length area of the flange part (11, 12) in the z-direction.
As illustrated in
According to the present embodiment, the stress applied to the wires W1 to W4 can be further relieved, and the volume of the core 10 can be increased more than in the coil component 4 according to the fourth embodiment.
Thus, higher magnetic characteristics can be obtained.
As illustrated in
The first area 11A is an area whose position in the x-direction overlaps the terminal electrodes 31 to 34, and the second area 11B is an area whose position in the x-direction does not overlap the terminal electrodes 31 to 34. Similarly, the first area 12A is an area whose position in the x-direction overlaps the terminal electrodes 35 to 38, and the second area 12B is an area whose position in the x-direction does not overlap the terminal electrodes 35 to 38. The first and second areas 11A and 11B form a step, and the position of the end portion of the second area 11B in the z-direction is lower than that of the first area 11A. Similarly, the first and second areas 12A and 12B form a step, and the position of the end portion of the second area 12B in the z-direction is lower than that of the first area 12A.
As exemplified in the present embodiment, when the flange part includes the first and second areas, it is possible to relieve the stress applied to the wires W1 to W4 by forming the grooves 41 to 44 (or steps 51 to 54) in the second area.
As illustrated in
Other configurations are basically the same as those of the coil component 6 according to the sixth embodiment, so the same reference numerals are given to the same elements, and overlapping description will be omitted.
The projections 61 and 62 have outer surfaces whose y-direction positions are substantially the same as those of the terminal electrodes 31 and 34 and constitute first positioning parts that position the drawn parts of the respective wires W1 and W4 in the y-direction. Similarly, the projections 63 and 64 have outer surfaces whose y-direction positions are substantially the same as those of the terminal electrodes 35 and 38 and constitute second positioning parts that position the drawn parts of the respective wires W2 and W3 in the y-direction.
As exemplified in the present embodiment, in the present invention, the positioning part need not be the groove or step, but may be the projection.
It is apparent that the present invention is not limited to the above embodiments, but may be modified and changed without departing from the scope and spirit of the invention.
Number | Date | Country | Kind |
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2018-076658 | Apr 2018 | JP | national |