JP2000068129A - Coil device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coil device for high frequency large current which can ensure high attaching stability and large mechanical connection strength. SOLUTION: A first core member 1 and a second core member 2 are overlapped mutually with each other. Trenches 41, 42 are stretched almost parallel in the longitudinal direction X with a gap kept in the widthwise direction Y and opened at both ends of the longitudinal direction X. A first and a second conductor edges 31, 32 of a coil conductor 3 face each other with a gap, one of the respective ends constitutes terminal parts 311, 321, and the other of the ends is continuous through a third conductor edge 33. The first and the second conductor edges 31, 32 are electrically insulated and inserted in the trenches 41, 42. The terminal parts 311, 321 and the third conductor edge 33 are bent in the same direction in the outside of the trenches 41, 42.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a coil device, and more particularly, to a coil device suitable for passing high frequency and large current.

[0002]

2. Description of the Related Art In recent years, the switching frequency of a switching power supply has been increased to 200 kHz or more due to demands for miniaturization and weight reduction. In such a high-frequency switching power supply, the coil device driven by the switching frequency requires only a small number of turns because the inductance may be small. However, since a large current of about 20 A flows, for example, a sufficiently large current capacity It is necessary to have Such a coil device is disclosed, for example, in Japanese Utility Model Laid-Open No. 2-101510. The coil device described in this known document has a one-turn structure in which a U-shaped coil conductor is insulated and sandwiched between a pair of E-shaped ferrite cores. The coil conductor is
It is obtained by processing a conductor plate such as a copper plate into a U shape.

[0003] Both ends of the U-shaped coil conductor are led out of the ferrite core, bent in the same direction, and the bent tip is used as an external connection terminal. The opposite side from both ends to be external connection terminals is a U-shaped bottom (returned portion), and is formed outside the pair of ferrite cores as a plane substantially parallel to the superposed surface of the pair of ferrite cores. Have been.

[0004]

The problem with the prior art described above is that since both ends of the U-shaped coil conductor are used as external connection terminals, they must be mounted on a circuit board or the like in a cantilevered state. It is easy to cause problems such as an unstable mounting state and an insufficient mechanical connection strength.

In addition, the coil conductor is disposed between the pair of ferrite cores, and the weight of the ferrite core is added to the cantilevered coil conductor. Also, the mechanical connection strength tends to deteriorate.

[0006] An object of the present invention is to provide a coil device suitable for passing a high frequency high current.

Another object of the present invention is to provide a coil device capable of securing a high degree of mounting stability and a large mechanical connection strength when mounted on a circuit board or the like.

Another object of the present invention is to provide a coil device having a structure suitable for reduction in size, thickness, and weight.

[0009]

In order to solve the above-mentioned problems, a coil device according to the present invention comprises a first core member,
A second core member and a coil conductor are included. The first core member and the second core member are overlapped so that one surface faces each other. At least one of the first core member and the second core member has at least one groove in a superposed surface.

[0010] The number of the grooves generated when the first core member and the second core member are overlapped is two. When the length direction and the width direction are imagined in the overlapping surface, the two grooves extend in the length direction at an interval from each other in the width direction, and are open at both ends in the length direction.

[0011] The coil conductor is formed of a metal conductor plate and includes a first conductor side, a second conductor side, and a third conductor side. The first conductor side and the second conductor side are:
The terminals face each other at an interval, one ends of which are terminal portions, and the other ends are connected to each other by the third conductor side.

The first conductor side and the second conductor side are inserted into the groove with electrical insulation.

According to the above configuration, a coil device is obtained in which a coil conductor of about one turn is disposed in two grooves on a surface where the first core member and the second core member are superposed. Since the coil conductor is formed of a metal conductor plate, the cross-sectional area increases, and a large current capacity is secured. Such a coil device is suitable for a high-frequency high-current circuit such as an output circuit of a chopper-type switching power supply.

The first core member and the second core member are superposed on each other with one surface facing each other, and the first conductor side and the first conductor side of the coil conductor are inserted into a groove formed in the superposed surface. Since the two conductor sides are inserted while being electrically insulated, a closed magnetic path is formed by the first core member and the second core member with respect to the magnetic flux generated by the current flowing through the coil conductor.

Further, the first conductor side and the second conductor side are
The terminals are opposed to each other at an interval, and one end of each terminal is a terminal portion. The terminal portion is led out of the groove and is bent in one direction when viewed in the overlapping direction. Therefore, both terminal portions of the first conductor side and the second conductor side can be used as external connection terminals, and can be connected and fixed to a conductor pattern provided on a circuit board or the like by means such as soldering.

Moreover, at least a part of the third conductor side located on the opposite side of both the first conductor side and the second conductor side from the terminal part is bent in the same direction as the terminal part outside the groove. Have been. Therefore, even on the opposite side of both the first conductor side and the second conductor side from both terminal portions, a part of the third conductor side is used as a dummy terminal and soldered to the dummy conductor pattern on the circuit board. The connection can be fixed by this means.

After all, as a mounting state, both terminal portions of the first conductor side and the second conductor side and a part of the third conductor side on the opposite side are connected to the conductor pattern on the circuit board. The structure is fixed by connection such as soldering. For this reason, when mounted on a circuit board or the like, a high degree of mounting stability and high mechanical connection strength can be ensured.

Preferably, both terminal portions of the first conductor side and the second conductor side and the third conductor side are bent along the side surface of the first core member. According to this structure, the length and length can be minimized, and the size and weight can be reduced.
Moreover, since the third conductor side operates as a heat radiating portion,
Heat dissipation can be improved.

In a further preferred aspect, the first core member has an inclined surface between the bottom surface facing the overlapping surface and the side surface. The inclined surface may be the first core member or the second core member.
As the distance from the outer surface of the core member increases, the distance between the terminal portion and the third conductor side is increased. According to this structure, even when the terminal portion and the third conductor side are bent close to the side surfaces of the first core member and the second core member, the terminal portion and the third conductor side are bent by the inclined side. Between the conductor side and the first core member and the second core member,
A large solder adhesion space is generated, and sufficient soldering strength can be secured.

The coil device according to the present invention can be used for a switching circuit. A specific example of such a switching circuit is a switching power supply that converts a switching output of a switch element into a DC voltage and outputs the DC voltage, in particular, a chopper switching power supply.

Other objects, configurations and advantages of the present invention will be described more specifically with reference to the accompanying drawings. The accompanying drawings merely show examples.

[0022]

FIG. 1 is an exploded perspective view of a coil device according to the present invention, FIG. 2 is an external perspective view of the coil device shown in FIG. 1, and FIG. 3 shows the coil device shown in FIG. FIG. 4 is a cross-sectional view taken along line 4-4 in FIG. As shown, the coil device according to the present invention comprises:
It includes a first core member 1, a second core member 2, and a coil conductor 3. First core member 1 and second core member 2
Are superposed on each other so as to face each other. The first core member 1 and the second core member 2 may be joined by an adhesive or the like on the overlapping surface, or may be joined to each other by an elastic band or tape. First core member 1 and second core member 2
Can be made of, for example, a MnZn-based ferrite, a NiZn-based ferrite magnetic material, or the like. The first core member 1 and the second core member 2 may have substantially the same or different magnetic properties.

At least one of the first core member 1 and the second core member 2 has at least one groove 41, 42 on the overlapping surface. The number of grooves 41 and 42 generated when the first core member 1 and the second core member 2 are overlapped is two. In preparing the two grooves 41 and 42,
One of the grooves 41 and 42 is provided in the first core member 1 and the groove 4
A structure in which the other of the first and second members 42 may be provided in the second core member 2, or a structure in which the two grooves 41 and 42 are provided in one of the first core member 1 and the second core member 2.

In the embodiment, the two grooves 41, 42
The core member 1 is provided on the superposed surface. When the length direction X and the width direction Y are imagined on the superposed surface, these grooves 41 and 42 extend substantially parallel to the length direction X at intervals in the width direction Y, and both ends in the length direction X. It is open at. The second core member 2 has a flat overlapping surface.

The coil conductor 3 is constituted by a metal conductor plate,
It includes a first conductor side 31, a second conductor side 32, and a third conductor side 33. The coil conductor 3 is, for example, 0.5 m
It can be manufactured by punching a copper plate having a thickness of at least m. The first conductor side 31 and the second conductor side 32 face each other at an interval, and one end of each of the first conductor side 31 and the second conductor
1, 321 and the other ends are connected to each other by the third conductor side 33. The first conductor side 31 and the second conductor side 32 are inserted into the grooves 41 and 42 with electrical insulation. The first conductor side 31, the second conductor side 32, and the third
The width of the conductor side 33 is determined in consideration of the flowing current, based on the above-described thickness. As an example, for a switching power supply, a thickness of 0.5 mm, 2-3 mm
It is selected in the range of about.

According to the above configuration, the first core member 1 and
A coil device in which the coil conductor 3 of about one turn is disposed inside the two grooves 41 and 42 on the surface to be overlapped with the second core member 2 is obtained. Since the coil conductor 3 is formed of a metal conductor plate, the cross-sectional area increases, and a large current capacity is secured. Such a coil device,
For example, it is suitable for a high-frequency high-current circuit such as an output circuit of a chopper-type switching power supply.

The first core member 1 and the second core member 2 are superposed on each other so as to face each other. The grooves 41 and 42 formed on the superimposed surfaces have the coil conductor 3 inside. Since the first conductor side 31 and the second conductor side 32 are configured to be electrically insulated and inserted, the first core member 1 and the second core A closed magnetic path is formed by the member 2.

First conductor side 31 and second conductor side 32
Are opposed to each other at an interval, one ends of which are terminal portions 311 and 321, respectively.
Are led out of the grooves 41 and 42 and are bent in one direction when viewed in the overlapping direction. Therefore, when mounting on the circuit board, as shown in FIG. 5, both terminal portions 311, 3 of the first conductor side 31 and the second conductor side 32 are provided.
21 can be used as an external connection terminal and can be connected and fixed to a conductor pattern 51 provided on the circuit board 5 by means of soldering 61 or the like.

Further, at least a part of the third conductor side 33 located on the opposite side of the first conductor side 31 and the second conductor side 32 from the terminal portions 311 and 321 is formed outside the grooves 41 and 42. , And are bent in the same direction as the terminal portions 311 and 321. Therefore, as shown in FIG. 5, both terminal portions 311 and 321 of the first conductor side 31 and the second conductor side 32 are provided.
On the side opposite to the above, a part of the third conductor side 33 is used as a dummy terminal to form a dummy conductor pattern 5 on the circuit board 5.
2 can be connected and fixed by means such as soldering 62.

After all, the mounting state is as follows.
Not only the terminal portions 311 and 321 of the first and second conductor sides 32 but also a part of the third conductor side 33 on the opposite side are soldered to the conductor patterns 51 and 52 on the circuit board 5. A structure fixed and connected by means such as 61 and 62 is obtained. For this reason, when mounted on the circuit board 5, a high degree of mounting stability and a large mechanical connection strength can be ensured.

In the embodiment, both the terminal portions 311 and 321 of the first conductor side 31 and the second conductor side 32 and the third conductor side 33 extend along the side surfaces 11 and 12 of the first core member 1. Bendable. According to this structure, the length and length can be minimized, and the size and weight can be reduced. In addition, since the third conductor side 33 is located outside the first core member 1 and the second core member 2 and operates as a heat radiating portion, heat radiation is improved.

The terminal portions 311 and 321 and the third conductor side 33 are formed such that the tip ends thereof are the first core member 1 or the second
Is bent so as to protrude from the outer surface of the core member 2. According to this structure, the terminal portions 311 and 321 and the end portions of the third conductor side 33 are brought into contact with the conductor patterns 51 and 52 on the circuit board 5 to securely solder them 61 and 6.
You can do 2.

Further, in the embodiment shown in FIGS. 1 to 4, the first core member 1 is inclined at an angle θ between the outer surface (bottom surface) facing the overlapping surface and the side surfaces 11, 12. FIG.
(See FIG. 2). Inclined surface 13, 1
4 inclines in a direction to increase the distance between the terminal portions 311 and 321 and the third conductor side 33 as approaching the outer surface of the first core member 1 or the second core member 2. According to this structure, even when the terminal portions 311, 321 and the third conductor side 33 are bent close to the side surfaces of the first core member 1 and the second core member 2, the inclined surface 13,
14, a large solder adhesion space is generated between the terminal portions 311, 321 and the third conductor side 33 and the first core member 1 and the second core member 2, and the soldering 61, 6
The solder used in Step 2 is wrapped around this space (see FIG. 5) to ensure sufficient soldering strength.

The first conductor side 31 of the coil conductor 3 and the second conductor side 31
The following three aspects can be taken as means for electrically inserting the conductor side 32 into the grooves 41 and 42.

The first mode is that at least the coil conductor 3
Is to cover the first conductor side 31 and the second conductor side 32 with an electric insulating film.

FIG. 6 is a perspective view of the coil conductor subjected to the electrical insulation treatment according to the first embodiment, and FIG. 7 is a sectional view taken along the line 7-7 in FIG. In this embodiment, the first of the coil conductors 3
Almost the entire conductor side 31 and the second conductor side 32 are covered with an electric insulating film 30. The terminal portions 311, 321 and the third conductor side 33 are not covered with the electric insulating film 30 for soldering to the conductor pattern (see FIG. 5).
As the electric insulating film 30, for example, a fluorine film having a film thickness of about 50 μm is suitable. Such an electrical insulating film 30 made of a fluorine film can be formed by a coating technique.

According to the insulation treatment shown in FIGS. 6 and 7,
Since the coil conductor 3 can be directly incorporated into the first core member 1 and the second core member 3, the assembling work becomes easy and the number of assembling steps can be reduced. Further, as the material of the first core member 1 and the second core member 2, a material having good high-frequency magnetic characteristics is selected and used exclusively without much consideration of the level of electric insulation resistance to improve the magnetic characteristics. be able to.

The second aspect is to provide at least the inner surfaces of the grooves 41 and 42 with electric insulation. FIG. 8 shows the second
FIG. 9 is an enlarged side view of the first core member 1 shown in FIG. 8 and FIG.

As shown in the figure, the electric insulating film 30 is attached to the inner surfaces of the grooves 41 and 42. The electric insulating film 30 can be constituted by the above-mentioned fluorine film. When the second mode is adopted, the coil conductor 3 which is not subjected to the insulation treatment can be used, and the first core member 1 and the second core member 1 can be used.
As a material of the core member 2, a material having good high-frequency magnetic characteristics can be selected and used exclusively without much consideration of the level of electric insulation resistance, and the magnetic characteristics can be improved.

The third mode is that the first core member 1 and the second core member 1
The core member 2 is made of a magnetic material having electrical insulation. One example is the first core member 1 and the second core member 1.
Is made of a ferrite magnetic material having a high specific resistance value, for example, a NiZn-based ferrite magnetic material. Another example is the first core member 1 and the second core member 1.
The core member 2 is made of a composite magnetic material in which a magnetic powder such as a metal magnetic powder or a ferrite magnetic powder is mixed with an insulating resin. According to the third aspect, the coil conductor 3 that is not subjected to the insulation treatment can be used.

The coil device according to the present invention can be used for a switching circuit. Specifically, it is a switching power supply, particularly a chopper type switching power supply.
This switching power supply may be a step-up type or a step-down type.

FIG. 10 is a circuit diagram of a step-down type chopper switching power supply. This switching power supply
It includes a switch element 71, a choke coil 72, a diode 73, a capacitor 74, and a control circuit 75.
The choke coil 72 is constituted by a coil device according to the present invention. The switch element 71 includes a control circuit 75
The switching operation is controlled by the DC input voltage Vin supplied from the DC power supply 76 by, for example, 20
It switches at a high switching frequency of 0 kHz. During the ON period of the switch element 71, a current flows through the choke coil 72, and power is supplied to the load 77.

The energy stored in the choke coil 72 during the ON period of the switch element 71 is
During the off period of 1, the voltage is supplied to the load 77 through the diode 73.

The choke coil 72 is a coil device according to the present invention, and includes a first core member 1 and a second core member 2.
(See FIGS. 1 to 4), and the inductance is small, but there is no problem since the coil conductor 3 is used at a high switching frequency of 200 kHz or more. Moreover, the coil conductor 3
Is made of a metal conductor plate, so that its cross-sectional area becomes large and a large load current can flow.

[0045]

As described above, according to the present invention, the following effects can be obtained. (A) It is possible to provide a coil device suitable for passing a high-frequency large current. (B) When mounted on a circuit board or the like, it is possible to provide a coil device that can ensure a high degree of mounting stability and a large mechanical connection strength. (C) It is possible to provide a coil device having a structure suitable for reduction in size, thickness, and weight.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a coil device according to the present invention.

FIG. 2 is an external perspective view of the coil device shown in FIG.

FIG. 3 is a perspective view of the coil device shown in FIG. 1 as viewed from a direction opposite to FIG. 2;

FIG. 4 is a sectional view taken along line 4-4 in FIG. 2;

FIG. 5 is a view showing a use state of the coil device shown in FIGS. 1 to 4;

FIG. 6 is a perspective view of a coil conductor that has been subjected to an electrical insulation process according to the first embodiment.

FIG. 7 is a sectional view taken along the line 7-7 in FIG. 6;

FIG. 8 is a perspective view of a first core member subjected to an insulation process according to a second embodiment.

FIG. 9 is an enlarged side view of the first core member shown in FIG.

FIG. 10 is a circuit diagram of a switching power supply using the coil device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st core member 2 2nd core member 3 Coil conductor 31 1st conductor side 32 2nd conductor side 33 3rd conductor side 41, 42 Groove

Claims (9)

[Claims] A first core member, a second core member,
A coil device including a coil conductor, wherein the first core member and the second core member are overlapped with one surface facing each other, and the first core member and the second core member Has at least one groove on a superimposed surface, wherein the number of the grooves generated when the first core member and the second core member are superimposed is two, When the length direction and the width direction are imagined in the overlapping surface, the two grooves extend in the width direction in the length direction at an interval from each other, and are open at both ends in the length direction. Is composed of a metal conductor plate, and includes a first conductor side, a second conductor side, and a third conductor side. The first conductor side and the second conductor side are spaced apart from each other. Opposite each other, one end is a terminal part, the other end is The first conductor side and the second conductor side are inserted into the groove while being electrically insulated, and the terminal portion is led out of the groove. And a coil device which is bent in one direction as viewed in the overlapping direction, and at least a part belonging to the third conductor side is bent in the same direction as the terminal portion outside the groove. 2. The coil device according to claim 1, wherein the first core member and the second core member are made of a magnetic material having electrical insulation. 3. The coil device according to claim 2, wherein the first core member and the second core member are made of a ferrite magnetic material. 4. The coil device according to claim 1, wherein in the first core member and the second core member, at least an inner surface of the groove has electrical insulation. 5. The coil device according to claim 1, wherein at least a surface of the first conductor side and the second conductor side of the coil conductor is electrically insulated. . 6. The coil device according to claim 1, wherein the two grooves are provided in the first core member. 7. The coil device according to claim 6, wherein the terminal portion and the third conductor side are bent along a side surface of the first core member. 8. The coil device according to claim 7, wherein a tip of the terminal portion and the third conductor side protrudes from a bottom surface of the first core member. 9. The coil device according to claim 7, wherein the first core member has an inclined surface between the bottom surface facing the overlapping surface and the side surface. The coil device, wherein the inclined surface is inclined in a direction to increase a distance between the terminal portion and the third conductor side as approaching the bottom surface.