JP2002025827A - Coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent breakage of the corner sections of core members. SOLUTION: A core-combining member 5, which combines a pair of core members 4a and 4b with each other, is formed into a U-shape and has claw sections 14, formed by folding the front ends of the U-shaped leg sections 13. The corner sections 30 of the core member 4b, which come into contact with the folded corner sections 31 of the front ends of the leg sections 13, are rounded. The radius of curvature R' of the rounded sections are made larger than R of the folded corner sections 31 of the core-combining member 5. The folded corner sections 30 of the core member 4b come into face-contact with the inner peripheral surfaces of the folded corner sections 31, and the local impression of strong forces upon the corner sections 30 is prevented. Consequently, the breakage of the corner sections 30 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coil device functioning as a transformer or a choke coil.

[0002]

2. Description of the Related Art FIG. 9 (a) shows an example of a coil device in an exploded state, and FIG. 9 (b) is a sectional view of an AA portion of the coil device shown in FIG. 9 (a). ing. These FIG.
The coil device 1 shown in FIGS. 1A and 1B is incorporated in a circuit such as a DC-DC converter and functions as a transformer or a choke coil.
And a coil pattern portion 3 formed on the electronic component mounting board 2, a pair of core members 4 (4 a, 4 b), and a core combination member 5.

[0003] The electronic component mounting substrate 2 is a substrate on which electronic components constituting a circuit are mounted and a circuit pattern is formed. The electronic component mounting substrate 2 is a multi-layer substrate formed by laminating a plurality of substrates. For example, the coil patterns 7 are arranged and formed on the plurality of substrates constituting the electronic component mounting substrate 2 with their central axes coaxial. The coil pattern section 3 is configured by the plurality of coil patterns 7. When the coil device 1 is configured as a transformer device, at least one of the plurality of coil patterns 7 forms a primary coil, and the rest forms a secondary coil.

In the example shown in FIGS. 9 (a) and 9 (b), the paired core members 4a and 4b are both formed by pressing a magnetic material powder such as ferrite and sinter molding. A top plate portion 8 having a flat plate shape, and core legs 9 (9a, 9b, 9) standing upright at the center portion and left and right end portions of the top plate portion 8.
c) is an E-shaped core member having an E-shaped cross section.

In the electronic component mounting board 2, through holes 10 (10a, 10b) for inserting core feet into a board portion located at the center of the coil pattern portion 3 and a board portion outside the coil pattern portion 3 are provided. , 10c) are provided. These core leg insertion through holes 10a, 1
9b, each of the core feet 9 (9a, 9b, 9b, 9b, 9c, 9d) of the core members 4a, 4b from the front and back sides of the electronic component mounting board 2, respectively, as shown in FIG.
9c) is inserted, and the core feet 9 of the core member 4a on the front side and the core feet 9 of the core member 4b on the rear side are abutted.

[0006] The core combination member 5 corresponds to FIG.
As shown in (b), the paired core members 4a, 4b
The base plate 12, the feet 13, and the claws 14 are formed by bending a metal plate. In other words, both left and right sides of the base surface portion 12 covering the top plate portion 8 of the core member 4 are bent in the rising directions along the core feet 9 of the core member 4 to form the foot portions 13, and further, the tip of the foot portion 13 is formed. The side is bent inward to form the claw portion 14.

As shown in FIG. 9B, the distance between the base surface portion 12 and the claw portion 14 is the same as the core leg 9 of the core member 4a on the front side.
From the top surface 8a of the top plate portion 8 of the core member 4a to the top surface 8a of the top plate portion 8 of the core member 4b in a state where the core legs 9 of the core member 4b on the back side abut against each other. The distance h is substantially equal to the distance h. As shown in FIG. 9B, the core combination member 5 and the core members 4a and 4b in the butted state are fitted to each other, so that the base surface portion 12 and the claw portion 14 are positioned on both sides. And the left and right ends of the core members 4a and 4b in the butted state. This allows
The core members 4a and 4b are relatively formed by α shown in FIG.
They are combined so that they can move in the direction (front-back direction).
The length W in the front-rear direction of each of the core foot insertion through holes 10 is a length that allows the core member 4 to move in the front-rear direction as described above.

The coil device 1 shown in FIG. 9 is assembled as follows. First, a core member 4a is arranged on the front side of the electronic component mounting board 2 in which the coil pattern portion 3 and the core hole insertion through hole 10 are formed, and a core member 4b is arranged on the back side. Each core foot 9 of the core member 4a on the side is inserted from the surface side of the electronic component mounting board 2 into the corresponding core foot insertion through hole 10,
Similarly, each of the core feet 9 of the core member 4b on the back side is inserted from the back side of the electronic component mounting board 2 into the corresponding through hole 10 for inserting a core foot, so that the core feet 9 of the core member 4a on the front side are formed. 9 and the core leg 9 of the core member 4b on the back side are abutted.

Then, the core member 4 in the butted state is
From the upper side of a and 4b, the left foot 13a of the core combination member 5 is inserted into the left core foot insertion through hole 10a, and the right foot 13b of the core combination member 5 is inserted into the right core foot insertion hole. The core members 4 are inserted into the holes 10c at positions outside the core feet 9 respectively.

As a result, the core members 4a, 4b in the butted state and the core combination member 5 are fitted to each other,
The core members 4a and 4b are combined by the core combination member 5 and incorporated into the electronic component mounting board 2. By being incorporated into the electronic component mounting board 2 in this manner, the core members 4a and 4b are mounted on the coil pattern section 3 in such a manner that a part of the coil pattern section 3 is sandwiched from both front and back sides of the electronic component mounting board 2. The Rukoto.

Thereafter, the combined core member 4
The a and 4b are relatively slid in the front-rear direction so that the contact portions of the core members 4a and 4b, that is, the abutting end surfaces of the core feet 9 are rubbed against each other. In this manner, the tip surfaces of the core feet 9 are rubbed (rubbing of the cores).
, The following effects can be obtained.

That is, as described above, since the core member 4 is formed by sintering a magnetic material powder, the tip surface of the core foot 9 of the core member 4 is rough. Since dust enters between the front end surfaces of the butted core legs 9 during the assembling work of the core members 4a and 4b, the adhesion between the front end surfaces of the butted core legs 9 is low as it is. It is. On the other hand, as described above, by rubbing the cores and rubbing the tip surfaces of the core feet 9, the core feet 9 are rubbed.
Of the core foot 9 of the front-side core member 4a, since the tip face of the core member 4a is polished to a state close to a mirror surface, and dust entering between the tip faces of the core foot 9 is crushed and removed. And the front end surface of the core foot 9 of the core member 4b on the back side. Thus, the core members 4a,
By bringing the 4b into close contact, a decrease in the inductance value can be prevented, and the performance of the coil device can be prevented from deteriorating.

[0013]

By the way, in the configuration of the core combination member 5 as shown in FIG. 9, if the core member 4 is smaller than the design size, a gap is provided between the core members 4a and 4b and the core combination member 5. This causes a problem that the core combination member 5 cannot firmly hold the core members 4a and 4b. Also, on the contrary,
If the core member 4 is larger than the design dimension, the core combination member 5 and the pair of core members 4a and 4b cannot be fitted together, or even if the core combination member 5 can be fitted together, , 4b are applied with a very large force, and problems such as the inability to smoothly rub the core as described above occur. As described above, since the core members 4a and 4b are formed by sintering a magnetic material powder, the dimensional accuracy is not preferable, and the core member 4 often deviates from the design dimensions. For this reason, the core members 4a,
There has been a problem that failure of fitting of the 4b and the core combination member 5 frequently occurs.

Therefore, a core combination member 5 having a form as shown in FIG. 7A has been proposed. FIG. 7 (a)
The core combination member 5 shown in FIG. 1 is manufactured by bending a metal plate member, and includes a base surface portion 12 and the base surface portion 1.
2 has a substantially U-shape having leg portions 13 formed upright at both end positions. As shown in FIG. 7B, the core combination member 5 includes a pair of core members 4a,
Combine 4b.

In the configuration shown in FIG. 7A, the base surface 12 of the core combination member 5 is bent to have elasticity, and a concave portion is formed in the center of the base surface 12. The central recess of the base surface 12 is the core member 4.
And a pressing portion 12a for contacting and pressing the top surface 8a of the top plate portion 8. As shown in FIG. 7B, the distance H between the pressing portion 12a and the claw portion 14 is changed from the top surface 8a of the top plate 8 of the one core member 4a butted to the top of the other core member 4b. It is slightly smaller than the distance h to the top surface 8a of the plate portion 8.

For this reason, as shown in FIG.
When the core members 4a and 4b in the butted state and the core combination member 5 are fitted together, the feet 13 of the core combination member 5 are inclined outwardly away from the core member 4 from the lower side to the upper side in the drawing. In addition, the pressing portion 12a of the base surface portion 12 of the core combination member 5 applies a downward pressing force in the figure to the core member 4a. The pressing portions 12a of the base surface portion 12 of the core combination member 5 and the claw portions 14 cause the core members 4a,
4b is held and combined so as to be relatively movable in the front-rear direction.

By utilizing the core combination member 5 having the structure shown in FIG. 7, the core members 4a, 4b
Is slightly deviated from the design size, the pair of core members 4a, 4
b can be firmly held in a state in which it can smoothly slide in the front-rear direction.

The core combination member 5 is formed by bending a metal plate as described above, and as shown in FIG. 31 has a radius of curvature R (for example, R ≧ (t / 2)) corresponding to the thickness t of the metal plate in order to prevent the occurrence of cracks. On the contrary,
Since the core member 4 is formed by pressing a powder of a magnetic material such as ferrite and sintering the same, the corners 30 of the core member 4 can be formed in a right-angled shape. As such, the core member 4 (4
If the corner 30 of b) has a right-angled shape, the corner 3
No. 0 comes into line contact with the inner peripheral surface of the bent corner portion 31 of the core combination member 5 at only one location.

In such a case, a large force acts on the corner portion 30 of the core member 4b from the core combination member 5 to cause the corner portion 30 to be chipped, or the core portion 4b to be broken as shown in FIG. A gap s may be generated between the claw portion 14 of the combination member 5 and the core member 4b, which may adversely affect the combination state of the core members 4a and 4b.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to prevent a large force from being locally applied to a corner of a core member from a core combination member to prevent the core member from being applied. An object of the present invention is to provide a coil device that prevents breakage of a corner portion and improves the fitting state of a core member and a core combination member.

[0021]

Means for Solving the Problems In order to achieve the above object, the present invention has the following structure to solve the above problems. That is, a first aspect of the present invention provides a coil pattern portion formed on an electronic component mounting board; and a part of the coil pattern portion is mounted on the coil pattern portion so as to be sandwiched from both sides of the electronic component mounting substrate. A pair of core members; a through hole for inserting a core foot provided in an area where the coil pattern portion is formed and provided in at least one of the pair of core members; and a through hole for inserting a core foot. And a core combination member that combines the pair of core members by using the core combination member, wherein the core combination member has a base surface and foot portions formed to stand upright at both ends of the base surface. The tip of each foot is bent inward facing each other to form a claw, and the claw and the base surface are used to form the claw. The pair of core members are sandwiched and assembled from both sides, and the corner of the core member that contacts the bending corner at the tip of the foot in the core combining member has a curvature of the bending corner. It is characterized by being rounded with a radius of curvature greater than or equal to the radius.

According to a second aspect of the present invention, there is provided a coil pattern portion formed on an electronic component mounting board; a portion of the coil pattern portion being mounted on the coil pattern portion so as to be sandwiched from both sides of the electronic component mounting substrate. A pair of core members; a through hole for inserting a core foot provided in a region where the coil pattern portion is formed and provided in at least one of the pair of core members; and a through hole for inserting the core leg. A core combination member that combines the pair of core members by using a hole, wherein the core combination member has a base surface and legs that are respectively formed upright at both end positions of the base surface. The legs of the legs are bent inward to face each other to form a claw portion, and the claw portion and the base surface portion form a U-shape. The pair of core members are sandwiched from both front and back sides and combined, and the corners of the core members that contact the bent corners of the tips of the feet in the core combination member are chamfered corner cuts. It is characterized by being a part.

In the invention having the above structure, the corner of the core member which comes into contact with the bent corner at the tip of the foot in the core combined member is rounded with a radius of curvature equal to or larger than the radius of curvature of the bent corner. , Or a chamfered corner cut. Most of the corners of the core member having such a specific form come into surface contact with the inner peripheral surface of the bent corner of the core combination member, or come into surface contact or line contact at a plurality of locations, and It is possible to prevent a large force from being locally applied to the corner of the core member from the combination member. Accordingly, it is possible to reliably prevent the corner of the core member from being damaged due to the application of the force from the core combination member.

Further, the gap between the claw portion of the core combination member and the core member can be substantially eliminated, and the pair of core members can be more securely held between the claw portion and the base surface portion of the core combination member. As a result, it is possible to obtain a good combination state of the core members.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1A shows a characteristic core member extracted from the coil device of the first embodiment. The first embodiment is characterized in the configuration of the core member, and the other configurations are the same as those of the proposed coil device including the core combination member shown in FIGS.
In the description of the first embodiment, the same components as those of the coil device of the above-described proposal are denoted by the same reference numerals, and the description of the common portions will not be repeated.

The feature of the first embodiment is that the core member 4b comes into contact with the bent corner 31 at the tip of the foot 13 of the core combination member 5 as shown in FIGS. 8 (a) and 8 (b). Is rounded as shown in FIG. 1A. In the first embodiment, the roundness of the corner 30 of the core member 4b is such that the radius of curvature R 'thereof is larger than the radius of curvature R of the bent corner 31 of the core combination member 5 (R'≥R). It is round.

According to the first embodiment, the bent corner 31 at the tip of the foot 13 in the core combination member 5
Since the corner portion 30 of the core member 4b that comes into contact with the base member 4b is rounded with a radius of curvature R 'equal to or greater than the radius of curvature R of the bent corner portion 31, as shown in the enlarged view of FIG. The corner 30 of the core member 4b comes into surface contact with the inner peripheral surface of the bent corner 31 of the core combination member 5. For this reason, from the core combination member 5 to the core member 4
It is possible to prevent a very large force from being locally applied to the corner 30b, and to avoid damage to the corner 30 due to the application of the force from the core combination member 5.

Also, in the first embodiment, the corners 30 of the core member 4b are rounded as described above.
As shown in (b), a gap can be avoided between the claw portion 14 of the core combination member 5 and the core member 4b. Thereby, the core combination members 5 can combine the core members 4a and 4b in a very good state.

Incidentally, there is a coil device 1 having a form as shown in FIG. The coil device 1 shown in FIG. 10 is also similar to the coil device of the first embodiment.
Coil pattern portion 3 formed on electronic component mounting substrate 2
A pair of core members 4a and 4b are mounted on the pair of core members 4a and 4b.
a and 4b are combined by a clip-type core combining member 16.

The clip-type core combination member 16
Is a pair of core members 4a, 4b from the lateral direction shown in FIG.
Therefore, the pair of core members 4 a and 4 b must be arranged in the edge region of the electronic component mounting board 2. As described above, since the arrangement positions of the core members 4a and 4b are restricted, there is a problem that the degree of freedom of component arrangement on the electronic component mounting board 2 is reduced.

On the other hand, in the first embodiment,
As shown in FIGS. 7B and 8B, the core combination member 5 is of a type that is fitted from above the core members 4a and 4b, so that the core members 4a and 4b are attached to the electronic component mounting board 2. It is possible to arrange not only in the edge region but also in the central region, and the degree of freedom of component arrangement in the electronic component mounting board 2 can be increased.

When the clip-type core combination member 16 as shown in FIG. 10 is used, the clip-type core combination member 16 is easily detached, and the combination of the core members 4a and 4b is released. Therefore, there is a high possibility that such a serious problem occurs, and the reliability of the coil device 1 may be reduced. On the other hand, in the first embodiment, for example, as shown in FIG. 7B, the claw portion 14 is provided on the tip side of the foot portion 13 of the core combination member 5, so that the claw portion is provided. The configuration is such that the portion 14 is hooked on the core member 4b and the core combination member 5 can be reliably prevented from coming off. Thereby, the problem of a decrease in the reliability of the coil device 1 due to the detachment of the core combination member 5 can be suppressed.

Further, there is a case where a coil pattern (side coil pattern) centering on the left core leg 9a and the right core leg 9c of the core member 4 is formed.
In the configuration shown in FIG.
Is provided, and the core foot 9 (9a) is inserted through the notch 17, so that there is an inconvenience that a coil pattern centering on the core foot 9 (9a) cannot be formed.

On the other hand, in the first embodiment,
As described above, since the core member 4 can be arranged in a region other than the edge region of the electronic component mounting board 2, the core leg 9 is centered on any of the core legs 9 a and 9 c of the core member 4. Thus, it is possible to form a coil pattern having a predetermined shape, thereby increasing the degree of freedom in design.

Further, for example, as shown in FIG. 6, a circuit 2 such as an insulated DC-DC converter
After forming a plurality of circuit boards 1, the motherboard 20 may be cut along a dicing line 22 as shown by a dotted line in FIG. . In the configuration of the coil device 1 as shown in FIG. 10, the clip-type core combination member 16 is fitted from the lateral direction of the core members 4a and 4b. After that, the core member 4
The work of incorporating the a and 4b is performed. There is a problem that the work of assembling the core members 4a and 4b is not easy because the work is performed in a state of a finely divided substrate.

On the other hand, in the first embodiment,
As described above, the core combination member 5 includes the core members 4a, 4
b, the core members 4a and 4b are connected to the circuit using the core combination member 5 in the state of the motherboard 20 before being separated for each circuit board 21 as shown in FIG. 21 can be incorporated.
In this manner, the core member 4 is held in the state of the motherboard 20.
Since the work for assembling the core members 4a and 4b can be performed easily.

In the example shown in FIG. 1B, a gap is formed between the inner peripheral surface of the bent corner 31 of the core combination member 5 and the rounded portion of the corner 30 of the core member 4b. However, when the roundness of the corner portion 30 has a curvature radius R ′ substantially equal to the curvature radius R of the bent corner portion 31,
Most of the corners 30 are made of the core combination member 5
Are brought into surface contact with the inner peripheral surface of the bent corner portion 31.

Hereinafter, a second embodiment will be described. The characteristic of the second embodiment is that, as shown in FIG. 2A, the corner 30 of the core member 4 (4b) (that is, the corner 30)
The portion of the core combination member 5 that contacts the bent corner portion 31 at the tip of the foot portion 13) forms a corner cut portion. The other configuration is the same as that of the first embodiment. In the description of the second embodiment, the same components as those of the first embodiment are denoted by the same reference numerals, and the description of the common portions will be repeated. Is omitted.

In the second embodiment, as shown in FIG. 2B, the corner 30 of the core member 4 (4b) is
2B having a radius of curvature R ′ (a radius of curvature equal to or larger than the radius of curvature R of the bent corner portion 31 of the core combination member 5) shown in the embodiment, and having a rounded portion cut off. are doing.

According to the second embodiment, the core member 4
As shown in FIG. 2C, since the corner 30 of b is a corner cut, the corner 30 comes into line contact with the bent corner 31 of the core combination member 5 at a plurality of positions. A situation in which a very large force is locally applied to the corner 30 can be prevented. This allows
It is possible to prevent the corner 30 of the core member 4b from being damaged due to the application of the force from the core combination member 5. Also,
As shown in FIG. 2C, a gap between the claw portions 14 of the core member 4b and the core combination member 5 can be eliminated, and the core combination member 5 can further satisfactorily combine the pair of core members 4a and 4b. You can do it.

It should be noted that the present invention is not limited to the above embodiments, but can take various embodiments. For example, in the second embodiment, the corner 3 of the core member 4b is
Although there was only one cut surface, for example, as shown in FIG. 3, the corner portions 30 were formed so that a plurality of cut surfaces were formed.
May be corner-cut. In this case, the first
It is possible to approach the round shape of the corner 30 having a radius of curvature R ′ (a radius of curvature equal to or larger than the radius of curvature R of the bent corner 31 of the core combination member 5) as shown in the embodiment. The corner 30 having such a plurality of cut surfaces is formed on the inner peripheral surface of the bent corner 31 of the core combination member 5 by the second
Line contact occurs at a plurality of places more than in the embodiment, and the problem of breakage of the corner 30 of the core member 4b due to the application of force from the core combination member 5 can be avoided more reliably.

Further, in each of the above embodiments, the core combination member 5 has the shape shown in FIG. 7 and the like, but the shape of the core combination member 5 is not limited to the shape shown in each of the above embodiments. Instead, the shape may be, for example, as shown in FIG. Also in this case, the base portion 12 of the core combination member 5 is bent and formed to have elasticity, and the central portion 12a of the base portion 12 presses against the top plate 8 of the core member 4 by pressing. And

Further, in each of the above embodiments, the paired core members 4a and 4b are both E-shaped core members. For example, as shown in FIG. The member 4 may be an E-shaped core member, and the core member 4 on the other side may be an I-shaped core member having an I-shaped cross section. Further, as shown in FIG. 5B, an EER-type core member 4 having a columnar core foot 9b may be used. Further, FIG.
As shown in (c), a UR-type core having a U-shaped cross section, one of the two core legs 9 having a square pole shape, and the other core leg 9 having a columnar shape. The member 4 may be used. When the UR-type core member 4 is mounted on the coil pattern portion 3, one of the two core legs 9 is located at the center of the coil pattern portion 3 formed on the electronic component mounting board 2. And the other core leg 9 is disposed outside the coil pattern portion 3.

Each of the core members 4a and 4b shown in FIGS. 5A to 5C can be combined by the core combination member 5 having the same configuration as that shown in each of the above-described embodiments. The corner 30 of the core member 4 that contacts the bent corner 31 of the combination member 5 may be rounded in the same manner as in the first embodiment, or
By corner-cutting the corner 30 in the same manner as in the second embodiment, the same effect as in each of the above embodiments can be obtained.

[0046]

According to the present invention, the corner of the core member, which comes into contact with the bent corner at the tip of the foot in the core combined member, is rounded to have a radius of curvature equal to or greater than the radius of curvature of the bent corner. Or a configuration forming a chamfered corner cut portion. By providing such a configuration, most of the corners of the core member are brought into surface contact with the inner peripheral surface of the bent corners of the core combination member, or the corners of the core member are bent at the corners of the core combination member. Can be brought into surface contact or line contact with the inner peripheral surface at a plurality of locations.

For this reason, it is possible to avoid a situation where a very large force is locally applied to the corners of the core member from the core combination member, and it is possible to prevent the core member from applying a force from the core combination member. Damage can be prevented.

Further, the gap between the claw portion of the core combination member and the core member can be substantially eliminated. Thereby, the pair of core members can be more appropriately combined by the core combination member, and the reliability of the performance of the coil device can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a characteristic portion extracted from a coil device according to a first embodiment;

FIG. 2 is an explanatory diagram showing a characteristic portion extracted from a coil device according to a second embodiment;

FIG. 3 is an explanatory diagram showing another embodiment.

FIG. 4 is an explanatory view showing still another embodiment.

FIG. 5 is an explanatory view showing another embodiment of the core member.

FIG. 6 is a view for explaining effects obtained by using the core combination member shown in each of the above embodiments.

FIG. 7 is an explanatory view showing a proposal example of a core combination member.

FIG. 8 is a diagram for explaining a problem that occurs when the core combination member shown in FIG. 7 is used.

FIG. 9 is an explanatory view showing an example of a conventional coil device.

FIG. 10 is an explanatory view showing an example of a clip-type core combination member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Coil device 2 Electronic component mounting board 3 Coil pattern part 4 Core member 5 Core combination member 9 Core foot 10 Core foot insertion through hole 12 Base surface part 13 Foot part 14 Claw part 30 Corner part 31 Bent corner part

Claims (2)

[Claims] A coil pattern portion formed on an electronic component mounting substrate; and a pair of cores mounted on the coil pattern portion in such a manner that a part of the coil pattern portion is sandwiched from both sides of the electronic component mounting substrate. A member; a through hole for inserting a core foot provided in an area where the coil pattern portion is formed and provided in at least one of the pair of core members; and a through hole for inserting a core foot. And a core combination member for combining the pair of core members, wherein the core combination member has a substantially U-shape having a base surface and feet formed to stand upright at both ends of the base surface. The tip of each foot is bent inward facing each other to form a claw portion, and the claw portion and the base surface portion form the pair of legs. The core member is sandwiched from both the front and back sides and configured to be combined, and the corner of the core member that contacts the bending corner at the tip of the foot in the core combining member has a radius of curvature equal to or greater than the radius of curvature of the bending corner. A coil device characterized by being rounded with a radius of curvature. 2. A coil pattern portion formed on an electronic component mounting substrate; and a pair of cores mounted on the coil pattern portion in such a manner that a part of the coil pattern portion is sandwiched from both sides of the electronic component mounting substrate. A member; a through hole for inserting a core foot provided in an area where the coil pattern portion is formed and provided in at least one of the pair of core members; and a through hole for inserting a core foot. And a core combination member for combining the pair of core members, wherein the core combination member has a substantially U-shape having a base surface and feet formed to stand upright at both ends of the base surface. The tip of each foot is bent inward facing each other to form a claw portion, and the claw portion and the base surface portion form the pair of legs. The core member is sandwiched from both the front and back sides and combined, and the corner of the core member in contact with the bent corner at the tip of the foot in the core combination member is formed as a chamfered corner cut portion. A coil device characterized in that: