Coil component

This application claims benefit of priority to Japanese Patent Application No. 2020-188962, filed Nov. 12, 2020, the entire content of which is incorporated herein by reference.

The present disclosure relates to a coil component in which a wire is wound around a winding core of a core.

Background Art

Japanese Patent Application Laid-Open No. 2018-148078 discloses an example of a coil component in which a wire is wound around a winding core of a core. In this coil component, a terminal electrode is provided on a flange of the core, and an end of the wire is electrically connected to the terminal electrode.

An example of a method of electrically connecting the end of the wire to the terminal electrode will be described. For example, the end of the wire is temporarily fixed to the terminal electrode by thermal pressure bonding. By melting a metal constituting the terminal electrode in this state, a molten ball is created. The end of the wire can be electrically connected to the terminal electrode by the molten ball that become solidified.

When the metal constituting the terminal electrode is melted to create the molten ball, heat of the terminal electrode is also transferred to the wire whose end is temporarily fixed to the terminal electrode. The larger an amount of heat transferred to the wire is, the more greatly the wire is damaged.

Accordingly, a coil component includes a core having a winding core and a flange connected to an end of the winding core in an axial direction of the winding core, a terminal electrode provided on the flange, and a wire having an end and a winding portion wound around the winding core. The end is electrically connected to the terminal electrode. A part of the end is spaced apart from the terminal electrode.

In the above configuration, a part of the end of the wire is spaced apart from the terminal electrode. Therefore, heat is less likely to transfer from the terminal electrode to the wire as compared with a case where the end of the wire as a whole is in contact with the terminal electrode.

The present disclosure makes heat less likely to transfer from the terminal electrode to the wire.

FIG. 1 is a schematic perspective view illustrating an embodiment of a coil component;

FIG. 2 is a schematic side view of a part of the coil component;

FIG. 3 is a schematic view illustrating a connection state between an end of a wire and a terminal electrode in the coil component;

FIG. 4 is a schematic plan view of a part of the coil component; and

FIG. 5 is a schematic view illustrating a state in which the end of the wire is temporarily fixed to the terminal electrode when the coil component is produced.

Hereinafter, an embodiment of a coil component will be described with reference to FIGS. 1 to 5 . The drawings may show enlarged components to facilitate understanding. Dimensional ratios of the components may be different from those actual or those in another drawing. Although hatching is applied in a sectional view, hatching of some components may be omitted to facilitate understanding.

As illustrated in FIG. 1 , a coil component 10 includes a core 20 and a plurality of wires 31 and 41 wound around the core 20 . The coil component 10 is, for example, a common mode choke coil.

The core 20 contains, for example, an electrically insulating material. Specifically, the core 20 contains a non-magnetic material such as alumina or a resin, and a magnetic material such as ferrite or a magnetic powder-containing resin. The core 20 is preferably constituted by a sintered body such as alumina or ferrite.

The core 20 includes a winding core 21 , a first flange 22 connected to a first end of the winding core 21 in an axial direction Z 1 , and a second flange 23 connected to a second end of the winding core 21 in the axial direction Z 1 . That is, the winding core 21 extending in the axial direction Z 1 is disposed between a pair of the flanges 22 and 23 aligned in the axial direction Z 1 . The axial direction Z 1 is an extending direction of a central axis F of the winding core 21 .

Among side surfaces of the flanges 22 and 23 , a side surface corresponding to a circuit board when the coil component 10 is mounted on the circuit board is referred to as a mounting surface 25 a . In the embodiment, among directions orthogonal to the axial direction Z 1 , a direction along the mounting surface 25 a is referred to as a first direction Z 2 , and a direction orthogonal to the mounting surface 25 a is referred to as a second direction Z 3 .

Each of the flanges 22 and 23 protrudes outward in the first direction Z 2 from the winding core 21 and protrudes outward in the second direction Z 3 from the winding core 21 . The mounting surface 25 a is a side surface on a first side in the second direction Z 3 of the flanges 22 and 23 .

Recesses 26 are formed on both sides of each of the flanges 22 and 23 in the first direction Z 2 . By providing the recesses 26 , each of the flanges 22 and 23 has, as side surfaces, a longitudinal side surface 25 b connected to the mounting surface 25 a and a lateral side surface 25 c connected to the longitudinal side surface 25 b.

In the embodiment, the longitudinal side surface 25 b is formed such that an angle formed by the longitudinal side surface 25 b and the mounting surface 25 a is a right angle. The lateral side surface 25 c is a plane parallel to the mounting surface 25 a . However, it is sufficient that the angle formed by the longitudinal side surface 25 b and the mounting surface 25 a is substantially the right angle, and the angle need not be “90°”. It is sufficient that the lateral side surface 25 c is substantially parallel to the mounting surface 25 a , and the lateral side surface 25 c need not be precisely parallel to the mounting surface 25 a.

The coil component 10 includes a first terminal electrode 12 a and a second terminal electrode 12 b provided on the first flange 22 , and a third terminal electrode 12 c and a fourth terminal electrode 12 d provided on the second flange 23 . The first terminal electrode 12 a and the third terminal electrode 12 c are disposed on the first side with respect to the central axis F in the first direction Z 2 . The second terminal electrode 12 b and the fourth terminal electrode 12 d are disposed on the second side with respect to the central axis F in the first direction Z 2 . The second terminal electrode 12 b is located at an equal position to the first terminal electrode 12 a in the axial direction Z 1 . The fourth terminal electrode 12 d is located at an equal position to the third terminal electrode 12 c in the axial direction Z 1 .

Each of the terminal electrodes 12 a to 12 d is formed by processing a metal plate. That is, each of the terminal electrodes 12 a to 12 d has a base 131 located inside each of the recesses 26 in the first direction Z 2 . Each of the terminal electrodes 12 a to 12 d has a side wall 132 disposed along the longitudinal side surface 25 b . The side wall 132 is connected to the base 131 . Each of the terminal electrodes 12 a to 12 d has a connection 133 disposed on the lateral side surface 25 c . The connection 133 is coupled to the side wall 132 . That is, it can be said that the side wall 132 extends in the second direction Z 3 from a connected part with the connection 133 . Each connection 133 extends substantially in the axial direction Z 1 .

The first wire 31 and the second wire 41 are wound around the winding core 21 of the core 20 . In the embodiment, the first wire 31 and the second wire 41 are wound around the winding core 21 by lap winding. That is, the first wire 31 is directly wound around the winding core 21 , and the second wire 41 is wound around the winding core 21 over the first wire 31 . The number of windings of the first wire 31 around the winding core 21 is substantially the same as the number of windings of the second wire 41 around the winding core 21 .

A method of winding the first wire 31 and the second wire 41 around the winding core 21 need not be lap winding. For example, the first wire 31 and the second wire 41 may be wound around the winding core 21 by bifilar winding, or a region where the first wire 31 and the second wire 41 are wound around the winding core 21 by lap winding and a region where the first wire 31 and the second wire 41 are wound around the winding core 21 by bifilar winding may be both formed.

Each of the wires 31 and 41 has a winding portion 50 , a first end 51 , a second end 52 , a first extended portion 53 , and a second extended portion 54 . The winding portion 50 is a part of the wires 31 and 41 wound around the winding core 21 . FIG. 1 shows only a part of the winding portion 50 . The first end 51 is a part of the wires 31 and 41 located at an equal position to the first flange 22 in the axial direction Z 1 . The second end 52 is a part of the wires 31 and 41 located at an equal position to the second flange 23 in the axial direction Z 1 . The first extended portion 53 is a part of the wires 31 and 41 connecting the winding portion 50 and the first end 51 . The second extended portion 54 is a part of the wires 31 and 41 connecting the winding portion 50 and the second end 52 .

The first end 51 of the first wire 31 is electrically connected to the connection 133 of the first terminal electrode 12 a . That is, the first end 51 of the first wire 31 is electrically connected to the connection 133 by a molten ball 60 formed by dissolving a metal constituting the first terminal electrode 12 a . That is, the molten ball 60 , which becomes solidified as is simply referred to herein as the “molten ball 60 ”, and electrically connects the first terminal electrode 12 a and the first wire 31 , contains the metal constituting the first terminal electrode 12 a.

The first end 51 of the second wire 41 is electrically connected to the connection 133 of the second terminal electrode 12 b . That is, the first end 51 of the second wire 41 is electrically connected to the connection 133 by the molten ball 60 formed by dissolving a metal constituting the second terminal electrode 12 b . That is, the molten ball 60 electrically connecting the second terminal electrode 12 b and the second wire 41 contains the metal constituting the second terminal electrode 12 b.

The second end 52 of the first wire 31 is electrically connected to the connection 133 of the third terminal electrode 12 c . That is, the second end 52 of the first wire 31 is electrically connected to the connection 133 by the molten ball 60 formed by dissolving a metal constituting the third terminal electrode 12 c . That is, the molten ball 60 electrically connecting the third terminal electrode 12 c and the first wire 31 contains the metal constituting the third terminal electrode 12 c.

The second end 52 of the second wire 41 is electrically connected to the connection 133 of the fourth terminal electrode 12 d . That is, the second end 52 of the second wire 41 is electrically connected to the connection 133 by the molten ball 60 formed by dissolving a metal constituting the fourth terminal electrode 12 d . That is, the molten ball 60 electrically connecting the fourth terminal electrode 12 d and the second wire 41 contains the metal constituting the fourth terminal electrode 12 d.

Next, electrical connections between the terminal electrodes 12 a to 12 d and the ends of the wires 31 and 41 will be described in detail with reference to FIGS. 2 to 4 . FIGS. 2 to 4 illustrate an electrical connection between the first terminal electrode 12 a and the first end 51 of the first wire 31 . FIG. 2 is a part of a side view of the coil component 10 when the first flange 22 is viewed from a white arrow A 1 illustrated in FIG. 1 . FIG. 4 is a part of a side view of the coil component 10 when the first flange 22 is viewed from a white arrow A 2 illustrated in FIG. 1 . The arrow A 1 is an arrow extending in the first direction Z 2 . The arrow A 2 is an arrow extending in the second direction Z 3 .

As illustrated in FIGS. 2 and 3 , a part of the first end 51 is spaced apart from the connection 133 of the first terminal electrode 12 a . Specifically, a tip 51 a of the first end 51 is disposed in the molten ball 60 . The molten ball 60 is located on an opposite side of the winding core 21 with respect to a center of the first flange 22 in the axial direction Z 1 . When a part of the first end 51 spaced apart from the connection 133 is referred to as a “separate portion 51 b ”, the separate portion 51 b is disposed between the molten ball 60 and the winding core 21 in the axial direction Z 1 . That is, the separate portion 51 b is connected to the first extended portion 53 of the first wire 31 . A bent portion 56 that changes an extending direction of the first wire 31 is provided at a boundary between the separate portion 51 b and the first extended portion 53 .

A surface of the connection 133 is defined as a reference surface 133 a . In this case, a gap between the reference surface 133 a and the first wire 31 is preferably larger than or equal to a diameter D of the first wire 31 . In the embodiment, the gap is larger than the diameter D of the first wire 31 .

As illustrated in FIG. 2 , a part of the reference surface 133 a closer to the winding core 21 in the axial direction Z 1 than the molten ball 60 is an opposing surface facing the separate portion 51 b . In the embodiment, the separate portion 51 b extends in a direction along the reference surface 133 a . That is, the separate portion 51 b is parallel to the reference surface 133 a.

Of both ends of the connection 133 in the axial direction Z 1 , an end closer to the winding core 21 is referred to as an inner end 133 b of the connection 133 . In this case, the first wire 31 is not in contact with the inner end 133 b.

As illustrated in FIG. 3 , a positional relationship of the separate portion 51 b with respect to the reference surface 133 a preferably satisfies the following relational expression (Formula 1). In the relational expression (Formula 1), “X1” is a dimension of the molten ball 60 in a height direction. When a part of the molten ball 60 farthest from the reference surface 133 a in the second direction Z 3 is defined as a tip 61 of the molten ball 60 , the dimension of the molten ball 60 in the height direction is a distance between the reference surface 133 a and the tip 61 in the second direction Z 3 . That is, a dimension of the molten ball 60 in the second direction Z 3 is “X1”. In the relational expression (Formula 1), “X2” is a dimension from the reference surface 133 a to the separate portion 51 b in the second direction Z 3 corresponding to the height direction.

0< X 2≤ X 1·⅘  (Formula 1)

Accordingly, in the second direction Z 3 , the bent portion 56 of the first wire 31 is disposed between the tip 61 of the molten ball 60 and the reference surface 133 a . Furthermore, in the second direction Z 3 , the first extended portion 53 of the first wire 31 is disposed on an opposite side of the tip 61 across the bent portion 56 .

As illustrated in FIG. 4 , the separate portion 51 b of the first end 51 of the first wire 31 is not in contact with the side wall 132 of the first terminal electrode 12 a . That is, the separate portion 51 b is located outside the side wall 132 in the first direction Z 2 .

An electrical connection state between the second end 52 of the first wire 31 and the third terminal electrode 12 c , an electrical connection state between the first end 51 of the second wire 41 and the second terminal electrode 12 b , and an electrical connection state between the second end 52 of the second wire 41 and the fourth terminal electrode 12 d are equivalent to an electrical connection state between the first end 51 of the first wire 31 and the first terminal electrode 12 a . Therefore, a detailed description thereof will be omitted.

Next, an example of a method of electrically connecting the first end 51 of the first wire 31 to the first terminal electrode 12 a will be described with reference to FIG. 5 . An edge 511 of the first end 51 is pressed against the connection 133 of the first terminal electrode 12 a by a pressing member 100 in a direction indicated by an arrow in FIG. 5 . At this time, heat is applied to the edge 511 together with a pressing force. As a result, the edge 511 is temporarily fixed to the connection 133 by thermal pressure bonding. At this time, no pressing force is applied to a part of the first end 51 other than the edge 511 . Therefore, the part of the first end 51 other than the edge 511 is separated from the reference surface 133 a of the connection 133 in the second direction Z 3 . That is, the separate portion 51 b is formed.

When the temporary fixing is completed in this manner, the metal constituting the first terminal electrode 12 a is irradiated with a laser beam, and the metal is melted. At this time, a part of the first end 51 in contact with the first terminal electrode 12 a and a periphery of the part are also melted. Thus, the molten ball 60 is created. Then, as illustrated in FIG. 2 , the first end 51 of the first wire 31 is electrically connected to the first terminal electrode 12 a by the molten ball 60 . In FIG. 3 , a part indicated by a two-dot chain line of the first wire 31 is a part melted when the molten ball 60 is created.

When the first terminal electrode 12 a is irradiated with the laser beam, heat due to the irradiation of the laser beam is generated in the first terminal electrode 12 a . At this time, in a case where the first end 51 of the first wire 31 is as a whole in contact with the first terminal electrode 12 a , an amount of heat transferred from the first terminal electrode 12 a to the first wire 31 increases, and the first wire 31 is greatly damaged.

On the other hand, in the embodiment, a part of the first end 51 of the first wire 31 is not in contact with the first terminal electrode 12 a . Thus, when the molten ball 60 is formed, the amount of heat transferred from the first terminal electrode 12 a to the first wire 31 can be reduced. Accordingly, damage to the first wire 31 can be reduced.

In the embodiment, the following effects can be further obtained.

(1) A gap is interposed between each of the terminal electrodes 12 a to 12 d and the separate portion 51 b of the wires 31 and 41 . Therefore, when the coil component 10 is solder-mounted on the circuit board, the solder enters between each of the terminal electrodes 12 a to 12 d and the separate portion 51 b of the wires 31 and 41 . This can increase a connection strength when the coil component 10 is mounted on the circuit board.

(2) In the embodiment, as illustrated in FIG. 2 , the wires 31 and 41 are not in contact with the inner end 133 b of the connection 133 of each of the terminal electrodes 12 a to 12 d . As a result, it is possible to suppress disconnection of the wires 31 and 41 as compared with a case where the wires 31 and 41 are in contact with the inner end 133 b.

(3) In the embodiment, a gap between the reference surface 133 a of the connection 133 of each of the terminal electrodes 12 a to 12 d and the separate portion 51 b of the wires 31 and 41 is larger than the diameter D of the wires 31 and 41 . Therefore, as compared with a case where the separate portion Mb is close to the reference surface 133 a of the connection 133 , heat is less likely to transfer from the connection 133 of each of the terminal electrodes 12 a to 12 d to the wires 31 and 41 .

(4) In the embodiment, the separate portion Mb of the wires 31 and 41 are disposed between the tip 61 of the molten ball 60 and the reference surface 133 a in the second direction Z 3 . Accordingly, when the molten ball 60 is formed to electrically connect the wires 31 and 41 to the terminal electrodes 12 a to 12 d , the occurrence of connection failure can be reduced.

(5) In the embodiment, as illustrated in FIG. 3 , an angle θ formed between each of the ends 51 and 52 of the wires 31 and 41 and each of the extended portions 53 and 54 is larger than “90°” and smaller than “180°”. As a result, a stress on the wires 31 and 41 can be reduced as compared with the case where the angle θ is less than or equal to “90°”. Accordingly, when the molten ball 60 is formed to electrically connect the wires 31 and 41 to the terminal electrodes 12 a to 12 d , the occurrence of connection failure can be reduced.

(6) In the embodiment, as illustrated in FIG. 4 , the wires 31 and 41 are not in contact with the side walls 132 of the terminal electrodes 12 a to 12 d , either. As a result, the amount of heat transferred from the wires 31 and 41 from the connection 133 of each of the terminal electrodes 12 a to 12 d can be further reduced.

(7) In the embodiment, the above relational expression (Formula 1) is satisfied. Accordingly, when the molten ball 60 is formed to electrically connect the wires 31 and 41 to the terminal electrodes 12 a to 12 d , the occurrence of connection failure can be reduced.

The above embodiment can be modified as follows. The embodiment and the following modifications can be implemented in combination with each other so as not to technically contradict.

One of the first end 51 or the second end 52 of the first wire 31 may be in contact with the side walls 132 of the terminal electrode 12 a or 12 c.

One of the first end 51 or the second end 52 of the second wire 41 may be in contact with the side wall 132 of the terminal electrode 12 b or 12 d . The separate portion 51 b of the first end 51 of the first wire 31 need not be parallel to the reference surface 133 a of the connection 133 of the first terminal electrode 12 a.

The separate portion 51 b of the second end 52 of the first wire 31 need not be parallel to the reference surface 133 a of the connection 133 of the third terminal electrode 12 c . The separate portion 51 b of the first end 51 of the second wire 41 need not be parallel to the reference surface 133 a of the connection 133 of the second terminal electrode 12 b.

The separate portion 51 b of the second end 52 of the second wire 41 need not be parallel to the reference surface 133 a of the connection 133 of the fourth terminal electrode 12 d . A positional relationship between the separate portion 51 b of the first end 51 of the first wire 31 and the reference surface 133 a of the connection 133 of the first terminal electrode 12 a need not satisfy the relational expression (Formula 1).

A positional relationship between the separate portion 51 b of the second end 52 of the first wire 31 and the reference surface 133 a of the connection 133 of the third terminal electrode 12 c need not satisfy the relational expression (Formula 1).

A positional relationship between the separate portion 51 b of the first end 51 of the second wire 41 and the reference surface 133 a of the connection 133 of the second terminal electrode 12 b need not satisfy the relational expression (Formula 1).

A positional relationship between the separate portion 51 b of the second end 52 of the second wire 41 and the reference surface 133 a of the connection 133 of the fourth terminal electrode 12 d need not satisfy the relational expression (Formula 1).

The first extended portion 53 of the first wire 31 may have a part located on an opposite side of the reference surface 133 a across the bent portion 56 in the second direction Z 3 . The second extended portion 54 of the first wire 31 may have a part located on the opposite side of the reference surface 133 a across the bent portion 56 in the second direction Z 3 .

The first extended portion 53 of the second wire 41 may have a part located on the opposite side of the reference surface 133 a across the bent portion 56 in the second direction Z 3 . The second extended portion 54 of the second wire 41 may have a part located on the opposite side of the reference surface 133 a across the bent portion 56 in the second direction Z 3 .

The bent portion 56 provided at a boundary between the first end 51 and the first extended portion 53 of the first wire 31 may be located on an opposite side of the tip 61 of the molten ball 60 across the reference surface 133 a in the second direction Z 3 .

The bent portion 56 provided at a boundary between the second end 52 and the second extended portion 54 of the first wire 31 may be located on the opposite side of the tip 61 of the molten ball 60 across the reference surface 133 a in the second direction Z 3 .

The bent portion 56 provided at a boundary between the first end 51 and the first extended portion 53 of the second wire 41 may be located on the opposite side of the tip 61 of the molten ball 60 across the reference surface 133 a in the second direction Z 3 .

The bent portion 56 provided at a boundary between the second end 52 and the second extended portion 54 of the second wire 41 may be located on the opposite side of the tip 61 of the molten ball 60 across the reference surface 133 a in the second direction Z 3 .

A gap between at least a part of the separate portion 51 b of the first end 51 of the first wire 31 and the reference surface 133 a may be smaller than the diameter D of the first wire 31 . A gap between at least a part of the separate portion 51 b of the second end 52 of the first wire 31 and the reference surface 133 a may be smaller than the diameter D of the first wire 31 .

A gap between at least a part of the separate portion 51 b of the first end 51 of the second wire 41 and the reference surface 133 a may be smaller than the diameter D of the first wire 31 . A gap between at least a part of the separate portion 51 b of the second end 52 of the second wire 41 and the reference surface 133 a may be smaller than the diameter D of the first wire 31 .

The first wire 31 may be in contact with the inner end 133 b of the connection 133 of the first terminal electrode 12 a . The first wire 31 may be in contact with the inner end 133 b of the connection 133 of the third terminal electrode 12 c.

The second wire 41 may be in contact with the inner end 133 b of the connection 133 of the second terminal electrode 12 b . The second wire 41 may be in contact with the inner end 133 b of the connection 133 of the fourth terminal electrode 12 d.

If the separate portion 51 b can be formed at the first end 51 of the first wire 31 , the first end 51 may be electrically connected to the first terminal electrode 12 a by a method different from the method of electrically connecting the first end 51 to the first terminal electrode 12 a using the molten ball 60 . For example, the first end 51 may be electrically connected to the first terminal electrode 12 a using solder.

If the separate portion 51 b can be formed at the second end 52 of the first wire 31 , the second end 52 may be electrically connected to the third terminal electrode 12 c by a method different from the method of electrically connecting the second end 52 to the third terminal electrode 12 c using the molten ball 60 . For example, the first end 51 may be electrically connected to the first terminal electrode 12 a using solder.

If the separate portion 51 b can be formed at the first end 51 of the second wire 41 , the second end 52 may be electrically connected to the second terminal electrode 12 b by a method different from the method of electrically connecting the first end 51 to the second terminal electrode 12 b using the molten ball 60 . For example, the first end 51 may be electrically connected to the first terminal electrode 12 a using solder.

If the separate portion 51 b can be formed at the second end 52 of the second wire 41 , the second end 52 may be electrically connected to the fourth terminal electrode 12 d by a method different from the method of electrically connecting the second end 52 to the fourth terminal electrode 12 d using the molten ball 60 . For example, the first end 51 may be electrically connected to the first terminal electrode 12 a using solder.

If a part of the ends of the wires 31 and 41 is spaced apart from the connection 133 of the terminal electrode, the remaining part of the ends of the wires 31 and 41 may be in contact with the connection 133 . In the coil component, only one wire may be wound around the core.

The coil component need not be a common mode choke coil.