Winding-type coil component

Abstract

A winding-type coil component includes a first wire and a second wire having a twisted wire portion where the first wire and the second wire are twisted together. Switching positions of the first wire and the second wire in the twisted wire portion are shifted in a circumferential direction of a winding core portion every turn.

Claims

1. A winding-type coil component, comprising: a core including a winding core portion and a first flange portion and a second flange portion, the first flange portion and the second flange portion being provided on a first end of the winding core portion and a second end of the winding core portion, respectively, the first end and the second end being opposite to each other; and a first wire and a second wire wound around the winding core portion with substantially the same number of turns, not electrically connected to each other, and having a twisted wire portion where the first wire and the second wire are twisted together, wherein the winding-type coil component is mounted on a mount board with the winding core portion oriented parallel to the mount board, and each switching position of the first wire and the second wire in the twisted wire portion in a first turn of the winding core portion is shifted in a circumferential direction of the winding core portion relative to each switching position of the first wire and the second wire in the twisted wire portion in a second turn of the winding core portion, the second turn being adjacent to the first turn in an axial direction of the winding core portion.

2. The winding-type coil component according to claim 1, wherein when viewed from the mount board, a disposition of the first wire and the second wire in the first turn of the twisted wire portion is the same as or reverse to a disposition of the first wire and the second wire in a last turn of the twisted wire portion.

3. The winding-type coil component according to claim 1, wherein a total of shift amounts of the switching positions in all turns of the twisted wire portion is greater than a distance between adjacent switching positions in a same turn.

4. The winding-type coil component according to claim 1, wherein a surface of the winding core portion facing the mount board is a planar surface that is parallel to the mount board.

5. The winding-type coil component according to claim 4, wherein a sectional shape of the winding core portion that is perpendicular to a central axis thereof is a substantially rectangular shape.

6. The winding-type coil component according to claim 1, further comprising: a first terminal electrode and a third terminal electrode that are provided on the first flange portion; and a second terminal electrode and a fourth terminal electrode that are provided on the second flange portion, wherein one end portion and the other end portion of the first wire is connected to the first terminal electrode and the second terminal electrode, respectively, and one end portion and the other end portion of the second wire is connected to the third terminal electrode and the fourth terminal electrode, respectively.

7. The winding-type coil component according to claim 6, wherein the winding-type coil component is a common mode choke coil.

8. The winding-type coil component according to claim 1, wherein the number of turns of each of the first and second wires is about 15 or more.

9. The winding-type coil component according to claim 1, wherein the number of twists of the twisted wire portion per one turn is about three or less.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1A and 1B illustrate a common mode choke coil, serving as a winding-type coil component, according to a first embodiment of the present disclosure, with FIG. 1A being a bottom view of a surface facing a mount board and FIG. 1B being a front view and a partial sectional view along line 1-1 in FIG. 1A.

(2) FIG. 2A is an enlarged view of a state in which a first wire and a second wire are twisted together.

(3) FIG. 2B shows a form of illustration of a twisted wire including the two wires, the form of illustration being used in subsequent figures below.

(4) FIG. 3 shows in the form shown in FIG. 2B a wound state of the first and second wires viewed from a mount-board side of the common mode choke coil shown in FIG. 1.

(5) FIG. 4 is a bottom view corresponding to FIG. 1A and showing a common mode choke coil according to a comparative example.

(6) FIG. 5 shows in the form shown in FIG. 2B a wound state of first and second wires viewed from a mount-board side of the common mode choke coil shown in FIG. 4.

(7) FIGS. 6A and 6B each show a comparison between S-(Scattering)-parameter (Sdc21) frequency characteristics of the common mode choke coil according to the embodiment of the present disclosure and S-parameter (Sdc21) frequency characteristics of the common mode choke coil according to the comparative example, the comparisons being indicated for two cases, that is, a case shown in FIG. 6A in which the wires are close to the mount board and a case shown in FIG. 6B in which the wires are far from the mount board.

(8) FIG. 7 shows in the form shown in FIG. 2B a wound state of first and second wires viewed from a mount-board side of a common mode choke coil according to a second embodiment of the present disclosure.

(9) FIG. 8 shows in the form shown in FIG. 2B a wound state of first and second wires viewed from a mount-board side of a common mode choke coil according to a third embodiment of the present disclosure.

(10) FIG. 9 shows in the form shown in FIG. 2B a wound state of first and second wires viewed from a mount-board side of a common mode choke coil according to a fourth embodiment of the present disclosure.

(11) FIG. 10 shows in the form shown in FIG. 2B a wound state of first and second wires viewed from a mount-board side of a common mode choke coil according to a comparative example of the embodiment shown in FIG. 9.

(12) FIG. 11 shows in the form shown in FIG. 2B a wound state of first and second wires viewed from a mount-board side of a common mode choke coil according to a fifth embodiment of the present disclosure.

(13) FIG. 12 shows in the form shown in FIG. 2B a wound state of first and second wires viewed from a mount-board side of a common mode choke coil according to a sixth embodiment of the present disclosure.

(14) FIG. 13 shows in the form shown in FIG. 2B a wound state of first and second wires viewed from a mount-board side of a common mode choke coil according to a seventh embodiment of the present disclosure.

(15) FIG. 14 shows in the form shown in FIG. 2B a wound state of first and second wires viewed from a mount-board side of a common mode choke coil according to an eighth embodiment of the present disclosure.

(16) FIG. 15 shows a sectional shape that is perpendicular to a central axis of a winding core portion of a common mode choke coil according to a ninth embodiment of the present disclosure.

(17) FIG. 16 shows in the form shown in FIG. 2B a wound state of first and second wires viewed from a mount-board side of the common mode choke coil including the winding core portion shown in FIG. 15.

(18) FIG. 17 shows a sectional shape of a winding core portion that is perpendicular to a central axis of the winding core portion of a common mode choke coil according to a tenth embodiment of the present disclosure.

(19) FIG. 18 shows a sectional shape of a winding core portion that is perpendicular to a central axis of the winding core portion of a common mode choke coil according to an eleventh embodiment of the present disclosure.

(20) FIG. 19 shows a sectional shape of a winding core portion that is perpendicular to a central axis of the winding core portion of a common mode choke coil according to an twelfth embodiment of the present disclosure.

(21) FIG. 20 shows a sectional shape of a winding core portion that is perpendicular to a central axis of the winding core portion of a common mode choke coil according to a thirteenth embodiment of the present disclosure.

DETAILED DESCRIPTION

First Embodiment

(22) A common mode choke coil 1, serving as a coil component, according to a first embodiment of the present disclosure is described with reference to FIG. 1.

(23) The common mode choke coil 1 includes a substantially drum-shaped core 2, and a first wire 3 and a second wire 4, each constituting an inductor. In FIG. 1, in order to make it possible to clearly distinguish between the first wire 3 and the second wire 4, the first wire 3 is shown in white and the second wire 4 is shown in black.

(24) The core 2 is made of an electric insulating material, more specifically, for example, a nonmagnetic material, such as alumina, a magnetic material, such as NiZn-based ferrite, or resin. The wires 3 and 4 are each made of, for example, a copper wire subjected to insulating coating.

(25) The core 2 includes a winding core portion 5, and a first flange portion 9 and a second flange portion 10. The first flange portion 9 and the second flange portion 10 are provided on a first end 7 of the winding core portion 5 and a second end 8 of the winding core portion 5, respectively. The first end 7 and the second end 8 are opposite to each other. The sectional shape of the winding core portion 5 that is perpendicular to a central axis thereof is a substantially rectangular shape.

(26) A first terminal electrode 11 and a third terminal electrode 13 are provided on the first flange portion 9. A second terminal electrode 12 and a fourth terminal electrode 14 are provided on the second flange portion 10. The terminal electrodes 11 and 14 are formed by, for example, baking a conductive paste, plating with a conductive metal, or attaching a conductive metallic piece.

(27) One end portion and the other end portion of the first wire 3 is connected to the first terminal electrode 11 and the second terminal electrode 12, respectively. One end portion and the other end portion of the second wire 4 is connected to the third terminal electrode 13 and the fourth terminal electrode 14, respectively. These connections are performed by, for example, thermal pressure bonding or welding.

(28) Excluding the end portions of the first wire 3 that are connected to the first terminal electrode 11 and the second terminal electrode 12 and the end portions of the second wire 4 that are connected to the third terminal electrode 13 and the fourth terminal electrode 14, most of the first wire 3 and most of the second wire 4 are twisted together and configure a twisted wire portion. Ordinarily, the first wire 3 and the second wire 4 are twisted together while winding the first wire 3 and the second wire 4 around the winding core portion 5. The first wire 3 and the second wire 4 in the twisted wire portion are helically wound around the winding core portion 5 with substantially the same number of turns. Since, as mentioned above, the first wire 3 and the second wire 4 are subjected to insulating coating, the first wire 3 and the second wire 4 are not electrically connected to each other.

(29) The first wire 3 and the second wire 4 may have portions that are not twisted together other than at the end portions of the first wire 3 that are connected to the terminal electrodes 11 and 12 and at the end portions of the second wire 4 that are connected to the terminal electrodes 13 and 14. That is, a first wire 3 and the second wire 4 have at least a twisted wire portion where the first wire 3 and the second wire 4 are twisted together.

(30) As shown by an alternate long and two short dashed line in FIG. 1B, the common mode choke coil 1 may include a substantially plate-shaped core 15. As with the substantially drum-shaped core 2, the substantially plate-shaped core 15 is made of, for example, a nonmagnetic material, such as alumina, a magnetic material, such as NiZn-based ferrite, or resin. When the substantially drum-shaped core 2 and the substantially plate-shaped core 15 are made of magnetic materials, the substantially plate-shaped core 15 is provided so as to connect the first flange portion 9 and the second flange portion 10, so that the substantially drum-shaped core 2 cooperates with the substantially plate-shaped core 15 to form a closed magnetic path.

(31) As shown by an alternate long and short dashed line in FIG. 1B, the common mode choke coil 1 is intended to be mounted on a mount board 16. That is, the common mode choke coil 1 is intended to be mounted on the mount board 16 with the winding core portion 5 oriented parallel to the mount board 16 for applying a reference potential. At this time, the terminal electrodes 11 to 14 face the mount board 16, and are electrically and mechanically connected to conductive lands of the mount board 16.

(32) FIGS. 2A and 2B show forms of illustrations of a twisted wire portion 17 including the two wires, that is, the wires 3 and 4, the forms of illustration being used in, for example, FIG. 3 and subsequent figures. FIG. 2A is an enlarged front view of the twisted wire portion 17 where the first wire 3 and the second wire 4 are twisted together. FIG. 2B schematically shows the twisted wire portion 17 in FIG. 2A including the first wire 3 and the second wire 4. In FIGS. 2A and 2B, in order to make it possible to clearly distinguish between the first wire 3 and the second wire 4, the first wire 3 is shown in white and the second wire 4 is shown shaded. Although, in FIG. 2A, the twisted wire portion 17 is a Z-shaped twisted wire, the twisted wire may be an S-shaped twisted wire whose twisting direction is opposite to that of the Z-shaped twisted wire, or may be a wire including a Z-shaped twisted wire and an S-shaped twisted wire.

(33) FIG. 2A intends to show that the mount board 16 shown in FIG. 1B is positioned at a near side in the plane of FIG. 2A. Therefore, the winding core portion 5 exists on the far side in the plane of FIG. 2A.

(34) In the twisted wire portion 17 of the first wire 3 and the second wire 4 viewed from the mount board 16, as shown in FIG. 2A, when a direction that is perpendicular to the direction of extension of the twisted wire portion 17 is defined as a width direction, switching positions 18 of the first wire 3 and the second wire 4 are defined as positions where a wire that is larger in the width direction as viewed from the near side in the plane of FIG. 2A (that is, from the mount board 16) is switched from either one of the first wire 3 and the second wire 4 to the other of the first wire 3 and the second wire 4. In FIG. 2B, the twisted wire portion 17 is shown as a single wire, or a portion from a switching position 18 to the next switching position 18 is shown as the first wire 3 or the second wire 4. Such forms of illustrations are used in, for example, FIG. 3 and subsequent figures.

(35) The term switching means that the position of the first wire 3 and the position of the second wire 4 viewed from the mount board are directly opposite to each other. Two switchings are equivalent to one twist.

(36) The wound state of the twisted wire portion 17 including the first wire 3 and the second wire 4 of the common mode choke coil 1 shown in FIG. 1 is schematically shown in FIG. 3. In FIG. 1, a portion of the first wire 3 and a portion of the second wire 4 of the twisted wire portion 17 are shown as being separated from each other. However, as shown in FIG. 2A, the first wire 3 and the second wire 4 may be twisted together while in contact with each other. Although the states of the twisted wire portion 17 shown in FIGS. 1 and 3 are not the same, the wound state of the twisted wire portion 17 is described with reference to FIG. 3.

(37) With reference to FIG. 3, in the common mode choke coil 1, the switching positions 18 of the first wire 3 and the second wire 4 in the twisted wire portion are shifted in the circumferential direction D of the winding core portion 5 every turn.

(38) By virtue of such a structure described above, it is possible to prevent an accumulation amount (length, area) of a region where each wire opposes the mount board from being distributed towards one of the first wire 3 and the second wire 4. Therefore, it is possible to reduce the difference between the stray capacitance occurring between the mount board, on which the common mode choke coil 1 is mounted, and the first wire 3 and the stray capacitance occurring between the mount board, on which the common mode choke coil 1 is mounted, and the second wire 4. Therefore, it is possible to improve mode conversion characteristics of the common mode choke coil 1.

(39) FIG. 4 is a bottom view of a common mode choke coil 1a according to a comparative example. FIG. 4 corresponds to FIG. 1A. FIG. 5 shows in the form shown in FIG. 2B a wound state of a first wire 3 and a second wire 4 viewed from a mount-board side of the common mode choke coil 1a shown in FIG. 4. In FIGS. 4 and 5, corresponding elements to those shown in FIGS. 1A and 1B and FIG. 3 are given the same reference numerals, and the same descriptions thereof are not repeated.

(40) In the common mode choke coil 1a according to the comparative example, switching positions 18 of the first wire 3 and the second wire 4 in the twisted wire portion are not shifted in the circumferential direction D. In this case, if there is a difference between the stray capacitance at the first wire 3 and the stray capacitance at the second wire 4 in one turn, the difference between the stray capacitance occurring between the mount board, on which the common mode choke coil 1a is mounted, and the first wire 3 and the stray capacitance occurring between the mount board, on which the common mode choke coil 1a is mounted, and the second wire 4 accumulates as the winding extends. Therefore, the difference is larger than that in the common mode choke coil 1. Consequently, it is presumed that mode conversion characteristics deteriorate.

(41) FIGS. 6A and 6B each show a comparison between S-(Scattering)-parameter-(Sdc21) frequency characteristics, which are indicators of mode conversion characteristics, of the common mode choke coil 1 according to the embodiment of the present disclosure and S-parameter-(Sdc21) frequency characteristics, which are indicators of mode conversion characteristics, of the common mode choke coil 1a according to the comparative example, the comparisons being indicated for two cases, that is, a case shown in FIG. 6A in which the wires are close to the mount board and a case shown in FIG. 6B in which the wires are far from the mount board.

(42) In FIGS. 6A and 6B, the characteristics of the common mode choke coil 1 according to the embodiment are indicated by a solid line, and the characteristics of the common mode choke coil 1a according to the comparative example are indicated by a broken line. Here, the common mode choke coils 1 and 1a, serving as samples, each have a planar dimension of about 3.2 mm2.5 mm, the thickness of the substantially plate-shaped core 15 (refer to FIG. 1B) is about 0.7 mm, the diameters of the wires 3 and 4 are about 30 m, and the number of turns is about 15. In the common mode choke coil 1 according to the embodiment, the shift amount between the switching positions 18 for adjacent turns is about 1/15 of an outer periphery.

(43) FIGS. 6A and 6B show that, according to the common mode choke coil 1 according to the embodiment, Sdc21 is improved by approximately 7 dB in a frequency range greater than about 100 MHz compared to that in the common mode choke coil 1a according to the comparative example. Such an improvement in Sdc21 occurs when (A) the wires are close to the mount board and (B) when the wires are far from the mount board, so that the improvement does not depend upon the distance between each entire wire and the mount board.

(44) In the description below, FIGS. 7 to 14 and FIG. 16 are referred to. FIGS. 7 to 14 and FIG. 16 correspond to FIG. 3. Therefore, in each of FIGS. 7 to 14 and FIG. 16, elements corresponding to those shown in FIG. 3 are given the same reference numerals, and the same descriptions are not repeated.

Second Embodiment

(45) A common mode choke coil 21, serving as a coil component, according to a second embodiment of the present disclosure is described with reference to FIG. 7.

(46) The second embodiment is a special mode of the first embodiment. Therefore, the second embodiment includes the structure according to the first embodiment in which the switching positions 18 of the first wire 3 and the second wire 4 in the twisted wire portion are shifted in the circumferential direction D of the winding core portion 5 every turn, and also the following characteristic structure.

(47) That is, as shown in FIG. 7, when viewed from the mount board, a disposition of the first wire 3 and the second wire 4 in the first turn of the twisted wire portion is reverse to a disposition of the first wire 3 and the second wire 4 in the last turn of the twisted wire portion.

(48) According to this structure, regarding the entire first wire 3 and the entire second wire 4 in the twisted wire portion, the total length of a portion of the first wire 3 that is closer to the mount board and the total length of a portion of the second wire 4 that is closer to the mount board can be made close to each other.

Third Embodiment

(49) A common mode choke coil 22, serving as a coil component, according to a third embodiment of the present disclosure is described with reference to FIG. 8.

(50) As with the second embodiment, the third embodiment is a special mode of the first embodiment. Therefore, the third embodiment also includes the structure according to the first embodiment in which the switching positions 18 of the first wire 3 and the second wire 4 in the twisted wire portion are shifted in the circumferential direction D of the winding core portion 5 every turn.

(51) In the third embodiment, when viewed from the mount board, a disposition of the first wire 3 and the second wire 4 in the first turn of the twisted wire portion is the same as a disposition of the first wire 3 and the second wire 4 in the last turn of the twisted wire portion. A disposition of the first wire 3 and the second wire 4 in the intermediate turn of the twisted wire portion is reverse to the disposition of the first wire 3 and the second wire 4 in the first turn and the last turn.

(52) Even according to this structure, regarding the entire first wire 3 and the entire second wire 4, the total length of a portion of the first wire 3 that is closer to the mount board and the total length of a portion of the second wire 4 that is closer to the mount board can be made equal to each other.

(53) The effects provided by the above-described second and third embodiments can be provided if the disposition of the first wire 3 and the second wire 5 in the first turn of the twisted wire portion is the same as or reverse to the disposition of the first wire 3 and the second wire 4 in the last turn of the twisted wire portion. However, the intermediate turn where the disposition of the first wire 3 and the second wire 4 is the same as or reverse to the disposition of the first wire 3 and the second wire 4 in the first turn or the last turn may be any number of turns. There may be a plurality of the intermediate turns.

Fourth Embodiment

(54) A common mode choke coil 23, serving as a coil component, according to a fourth embodiment of the present disclosure is described with reference to FIG. 9.

(55) As with the second and third embodiments, the fourth embodiment is a special mode of the first embodiment. Therefore, the fourth embodiment also includes the structure according to the first embodiment in which the switching positions 18 of the first wire 3 and the second wire 4 in the twisted wire portion are shifted in the circumferential direction D of the winding core portion 5 every turn.

(56) Further, in the fourth embodiment, the total of shift amounts 19 of the switching positions 18 in all turns of the twisted wire portion is greater than the distance between adjacent switching positions 18a and 18b in a same turn. The switching position 18a is the position where the first wire 3 switches to the second wire 4, and the switching position 18b is the position where the second wire 4 switches to the first wire 3.

(57) Even according to this structure, in a portion between the first turn of the twisted wire portion and the last turn of the twisted wire portion, there exist some turns which have the disposition of the first wire 3 and the second wire 4 viewed from the mount board reverse to each other. Therefore, regarding the entire first wire 3 and the entire second wire 4 in the twisted wire portion, the difference between the total length of a portion of the first wire 3 that is closer to the mount board and the total length of a portion of the second wire 4 that is closer to the mount board can be less than or equal to a certain difference, that is, can be less than or equal to the distance between the switching position 18a and the switching position 18b. Consequently, the difference between the stray capacitance at the first wire 3 side and the stray capacitance at the second wire 4 side can fall within a certain range.

(58) FIG. 10 corresponds to FIG. 9, and shows a common mode choke coil 23a according to a comparative example of the embodiment shown in FIG. 9. The number of turns of wires 3 and of the common mode choke coil 23 shown in FIG. 9 and the number of turns of wires 3 and 4 of the common mode choke coil 23a shown in FIG. 10 are the same.

(59) Unlike the above-described case, as shown in FIG. 10, when a shift amount 19 between switching positions 18 of the first wire 3 and the second wire 4 in the twisted wire portion is small, any turns where the dispositions of the first wire 3 and the position of the second wire 4 are reverse to each other cannot both exist together. Therefore, regarding the entire first wire 3 and the entire second wire 4, the difference between the length of a portion of the first wire 3 that is closer to the mount board and the length of a portion of the second wire 4 that is closer to the mount board remains relatively large, and cannot be less than or equal to a certain difference.

Fifth Embodiment

(60) A common mode choke coil 24, serving as a coil component, according to a fifth embodiment of the present disclosure is described with reference to FIG. 11.

(61) In the fifth embodiment, unlike in the first embodiment, switching positions 18 in the twisted wire portion are not shifted in the circumferential direction D. In the fifth embodiment, as shown in FIG. 11, when viewed from a mount board, the total length of a portion of the first wire 3 that is closer to the mount board than the second wire 4 and the total length of a portion of the second wire 4 that is closer to the mount board than the first wire 3 are equal to each other in each turn of the twisted wire portion.

(62) According to such a structure, the length of the portion of the first wire 3 that is closer to the mount board and the length of the portion of the second wire 4 that is closer to the mount board can be the same in each turn. Therefore, even the fifth embodiment provides the same effects as those provided by the first to fourth embodiments.

Sixth Embodiment

(63) A common mode choke coil 25, serving as a coil component, according to a sixth embodiment of the present disclosure is described with reference to FIG. 12.

(64) The sixth embodiment has similar characteristics to those according to the above-described fifth embodiment. That is, when viewed from a mount board, the total length of a portion of the first wire 3 that is closer to a mount board than the second wire 4 and the total length of a portion of the second wire 4 that is closer to the mount board than the first wire 3 are equal to each other in each turn of the twisted wire portion.

(65) In the fifth embodiment, as shown in FIG. 11, there are four switching positions 18 for one turn, whereas, in the sixth embodiment, as shown in FIG. 12, there are two switching positions 18.

Seventh Embodiment

(66) A common mode choke coil 26, serving as a coil component, according to a seventh embodiment of the present disclosure is described with reference to FIG. 13.

(67) The seventh embodiment also has similar characteristics to those according to the above-described fifth embodiment. The seventh embodiment differs from the fifth embodiment in that switching positions 18 of a first wire 3 and a second wire 4 in the twisted wire portion are shifted in a circumferential direction D of a winding core portion 5. Even here, when viewed from a mount board, the total length of a portion of the first wire 3 that is closer to the mount board than the second wire 4 and the total length of a portion of the second wire 4 that is closer to the mount board than the first wire 3 are kept equal to each other in each turn of the twisted wire portion.

Eighth Embodiment

(68) A common mode choke coil 27, serving as a coil component, according to an eighth embodiment of the present disclosure is described with reference to FIG. 14.

(69) In the fifth to seventh embodiments, when viewed from a mount board, the total length of the portion of the first wire 3 that is closer to the mount board than the second wire 4 and the total length of the portion of the second wire 4 that is closer to the mount board than the first wire 3 are equal to each other in each turn. However, in the eighth embodiment, as shown in FIG. 14, they are equal to each other in each two turns of the twisted wire portion that are adjacent to each other.

(70) According to such a structure, the total length of the portion of the first wire 3 that is closer to the mount board and the total length of the portion of the second wire 4 that is closer to the mount board can be made equal to each other in each two turns.

(71) Such a structure according to the eighth embodiment is realized when the number of switchings in one turn of the first wire 3 and the second wire 4 is an odd number.

(72) When viewed from the mount board, the total length of the portion of the first wire 3 that is closer to the mount board than the second wire 4 and the total length of the portion of the second wire 4 that is closer to the mount board than the first wire 3 are equal to each other in each turn of the twisted wire portion in the fifth to seventh embodiments and in each two turns of the twisted wire portion that are adjacent to each other in the eighth embodiment. However, they may be equal to each other in each three or more turns that are adjacent to each other. That is, when they may be equal to each other in each N turns of the twisted wire portion that are adjacent to each other, and N is a natural number including one.

(73) In the above-described first to eighth embodiments, it is desirable that a surface of the winding core portion 5 facing the mount board be a planar surface that is parallel to the mount board, and it is more desirable that the sectional shape of the winding core portion 5 that is perpendicular to a central axis thereof be a substantially rectangular shape. According to this structure, regarding the first wire 3 and the second wire 4, the stray capacitance occurring between the portion of the first wire 3 that is closer to the mount board and the stray capacitance occurring between the portion of the second wire 4 that is closer to the mount board are proportional to the length of the portion of the first wire 3 that is closer to the mount board and the length of the portion of the second wire 4 that is closer to the mount board. Therefore, it becomes easier to provide a design for equalizing the stray capacitance occurring in association with the first wire 3 and the stray capacitance occurring in association with the second wire 4.

(74) In contrast, in the embodiments described below, the sectional shape of a winding core portion 5 that is perpendicular to a central axis thereof is a substantially protruding shape extending towards a mount board. In this case, in order to reduce the difference between a first stray capacitance occurring between a first wire 3 and the mount board and a second stray capacitance occurring between a second wire 4 and the mount board, of the first wire 3 and the second wire 4, as viewed from the mount board, an opposing area of the nearer wire opposing the mount board is smaller than an opposing area of the farther wire opposing the mount board.

Ninth Embodiment

(75) A common mode choke coil 28, serving as a coil component, according to a ninth embodiment of the present disclosure is described with reference to FIGS. 15 and 16.

(76) In the ninth embodiment, as shown in FIG. 15, the sectional shape of the winding core portion 5 that is perpendicular to a central axis thereof is substantially circular. The substantially circular shape may refer to a perfect circle or an elliptical shape. As shown in FIG. 16, in twisted wire portion of the first wire 3 and the second wire 4, when viewed from the mount board, a facing area of the nearest wire (in this case the second wire 4) to the mount board between the first wire 3 and the second wire 4 is smaller than a facing area of the other wire (that is, the first wire 3) between the first wire 3 and the second wire 4.

(77) As the facing area of a pair of electrodes that face each other is increased, the electrostatic capacity increases; and, as the distance between the pair of electrodes decreases, the electrostatic capacity increases. Therefore, the above-described structure makes it possible to balance the stray capacitance at the first wire 3 and the stray capacitance at the second wire 4.

(78) Such a twisted wire portion of the wire 3 and the wire 4 is even used in the tenth to thirteenth embodiments below.

Tenth Embodiment

(79) FIG. 17 shows the winding core portion 5 of a common mode choke coil 29, serving as a coil component, according to the tenth embodiment of the present disclosure.

(80) In the tenth embodiment, the sectional shape of the winding core portion 5 that is perpendicular to a central axis thereof is such that a bottom side of a substantially oblong rectangular shape is rounded into a substantially protruding shape. In this case, the bottom side faces the mount board.

Eleventh Embodiment

(81) FIG. 18 shows the winding core portion 5 of a common mode choke coil 30, serving as a coil component, according to the eleventh embodiment of the present disclosure.

(82) In the eleventh embodiment, the sectional shape of the winding core portion 5 that is perpendicular to a central axis thereof is a substantially flat hexagonal shape. In this case, two downwardly facing sides in FIG. 18 face the mount board.

Twelfth Embodiment

(83) FIG. 19 shows the winding core portion 5 of a common mode choke coil 31, serving as a coil component, according to the twelfth embodiment of the present disclosure.

(84) In the twelfth embodiment, the sectional shape of the winding core portion 5 that is perpendicular to a central axis thereof is a substantially pentagonal shape including a substantially triangular shape in which two sides of a substantially protruding shape are formed on a bottom side of a substantially oblong rectangular shape. In this case, two downwardly facing sides in FIG. 19 face the mount board.

(85) Regarding the embodiment shown in FIG. 19, for example, the winding core portion 5 may have a sectional shape whose upper and lower sides are the reverse of those of the shape shown in FIG. 19, in which the bottom side is flat and the upper side has a substantially protruding shape instead of being flat.

Thirteenth Embodiment

(86) FIG. 20 shows the winding core portion 5 of a common mode choke coil 32, serving as a coil component, according to the thirteenth embodiment of the present disclosure.

(87) In the thirteenth embodiment, the sectional shape of the winding core portion 5 that is perpendicular to a central axis thereof is a shape including two substantially rectangular protruding portions on respective ends of a substantially oblong ellipse in a major-axis direction thereof. In this case, the downwardly facing sides in FIG. 20 face the mount board.

(88) In all of the embodiments described above, it is desirable that the number of turns of the first wire 3 and the second wire 4 be about 15 or more. For example, in the winding-type coil component having a planar dimension of about 4.5 mm3.2 mm, when the number of turns is about 15 or more, it is possible to obtain an inductance of at least about 50 H.

(89) In the structure according to the comparative example shown in FIG. 4, the difference between the stray capacitance at the first wire 3 and the stray capacitance at the second wire 4 accumulates with every turn. Therefore, in proportion to the number of turns, the difference increases. Consequently, as described above, as the number of turns increases, the structure according to the present disclosure becomes more effective.

(90) In all of the embodiments, it is desirable that the number of twists of the twisted wire portion per one turn be about three or less, that is, the number of switchings of the first wire 3 and the second wire 4 in the twisted wire portion per one turn be about six or less. In this way, when the number of twists is about three or less, the opposing area between the mount substrate and one of the two wires 3 and 4 and the opposing area between the mount substrate and the other of the two wires 3 and 4, and the distance between the mount substrate and one of the two wires 3 and 4 and the distance between the mount substrate and the other of the two wires 3 and 4 tend to differ from each other. Therefore, mode conversion characteristics tend to deteriorate. Consequently, the structure according to present disclosure is more effective.

(91) The phrase the number of twists is about three or less may refer to the number of twists that correspond to an odd number of switchings, such as 0.5, 1.5, or 2.5. Since the number of twists per one turn is an issue, for example, the number of twists may be intermediate values, such as 2.1 to 2.9. However, as described above, although some modifications can be considered, it is desirable that the number of twists be an integral number from the start of the winding to the end of the winding.

(92) The first wire 3 and the second wire 4 may be wound in about two layers or more. In this way, when they are wound in about two layers or more, basically, a portion of the wire that forms an outermost layer only needs to satisfy the structure according to the present disclosure. In other words, the two wires may be arbitrarily switched in an inner layer.

(93) Although the present disclosure is described in relation to the embodiments of the illustrated common mode choke coils, the present disclosure is applicable to, for example, BALUN or transformers.

(94) Although the illustrated embodiments are exemplifications, the structures according to different embodiments may be partly replaced or combined.

(95) While preferred embodiments of the disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the disclosure. The scope of the disclosure, therefore, is to be determined solely by the following claims.