JP7038275B2 - Inductors and their manufacturing methods - Google Patents

Description

The present invention relates to an inductor used in various electronic devices and a method for manufacturing the same.

Conventionally, inductors have been widely used in electronic devices such as DC-DC converter devices for the purpose of raising and lowering the power supply voltage, smoothing DC current, and the like.

In recent years, the switching frequency in the drive circuit of the DC-DC converter has shifted to the high frequency side, and the inductance value of the inductor has become smaller due to the higher frequency of the switching frequency.

Such low inductance value inductors include a core member, a flat plate-shaped conductor provided inside the core member and extending linearly, and an inductor provided on the outer surface of the core member and electrically connected to the conductor. At the same time, an inductor having a terminal electrode that is electrically connected to a mounting board to be mounted is known.

International Publication No. 2006/070544

As described above, in the conventional inductor configuration, the conductor provided inside the core member is a flat plate-shaped conductor. Therefore, if the conductor is flat-shaped, the magnetic flux path length circulating around the conductor becomes long. Therefore, there is a problem that the magnetic efficiency tends to decrease.

The present invention solves the above-mentioned conventional problems, and provides an inductor having high magnetic efficiency and a method for manufacturing the same, which suppresses a decrease in magnetic efficiency even in an inductor using a conductor stretched in a straight line. The purpose is.

In order to achieve the above object, one aspect of the present invention includes a conductor portion made of a metal plate and stretched linearly, an exterior body made of a magnetic material and covering the conductor portion, and an exterior body connected to the conductor portion and exposed from the exterior body. The conductor portion is bent in a bellows fold in the width direction.

Further, another aspect of the present invention includes a conductor portion made of a metal plate and stretched linearly, an exterior body made of a magnetic material and covering the conductor portion, and an external electrode connected to the conductor portion and exposed from the exterior body. In the method of manufacturing the conductor, the process of forming the conductor part includes a metal plate preparation step of preparing a linearly stretched metal plate and a bending conductor part forming step of bending the metal plate in a bellows fold in the width direction. Have.

According to one aspect of the present invention, since the conductor portion is bent in a bellows shape in the width direction, it is possible to obtain the effect that the magnetic efficiency of the inductor can be improved.

Further, according to another aspect of the present invention, the steps of forming the conductor portion include a metal plate preparation step of preparing a linearly stretched metal plate and a bent conductor portion forming in which the metal plate is bent in a bellows fold in the width direction. Since it has a process, it is possible to obtain the effect that the magnetic efficiency of the inductor can be improved.

Perspective view of the inductor according to the embodiment of the present invention. A transmission perspective view of an inductor according to an embodiment of the present invention. Sectional drawing of line AA in FIG. Sectional drawing of line BB in FIG. The figure explaining the manufacturing process of the inductor in one Embodiment of this invention. The figure explaining the manufacturing process of the inductor in one Embodiment of this invention. The figure explaining the manufacturing process of the inductor in one Embodiment of this invention. The figure explaining the manufacturing process of the inductor in one Embodiment of this invention. Sectional drawing which shows another example of the inductor in one Embodiment of this invention. Perspective view of a metal plate showing another example of an inductor in one embodiment of the present invention. Transmissive perspective view showing another example of the inductor in one embodiment of the present invention.

Hereinafter, the inductor according to the embodiment of the present invention will be described with reference to FIGS. 1 to 4.

1 is a perspective view of an inductor according to an embodiment of the present invention, FIG. 2 is a transmission perspective view of the inductor, FIG. 3 is a sectional view taken along line AA in FIG. 1, and FIG. 4 is FIG. It is sectional drawing of BB line.

Note that FIG. 2 is a transparent perspective view through the exterior body 20 described later, and the outline of the exterior body 20 is shown by a broken line.

As shown in FIGS. 1 to 4, the inductor 100 of the present embodiment has a conductor portion 10 made of a metal plate and linearly stretched, an exterior body 20 made of a magnetic material and covering the conductor portion 10, and a conductor portion. An external electrode 30 connected to 10 and exposed from the exterior body 20 is provided.

Here, in the present specification, as shown in FIG. 1, the direction in which the conductor portion 10 extends linearly is defined as the first direction 201, the tip direction of the arrow is the back side, and the side opposite to the tip of the arrow is the back side. Sometimes referred to as the front side.

Further, the direction orthogonal to the first direction 201 and along the width direction of the conductor portion 10 and the external electrode 30 is defined as the second direction 202, the tip direction of the arrow is the back side, and the side opposite to the tip of the arrow is the front side. May be called.

The direction orthogonal to the first direction 201 and the second direction 202 may be defined as the third direction 203, the tip direction of the arrow may be referred to as the upper side, and the side opposite to the tip of the arrow may be referred to as the lower side.

The first, second, and third directions are the same in the drawings after FIG. 1.

In the inductor 100 of the present embodiment, the exterior body 20 is made of a magnetic material in which a magnetic material powder and a binder are mixed. The magnetic material is made into granular granulated powder, and the conductor portion 10 is added to the granulated powder. It is embedded and pressure molded.

In this way, the exterior body 20 covers the conductor portion 10 and serves both as the magnetic core of the closed magnetic path of the inductor 100 and the exterior body 20 which is the main body portion of the inductor 100.

Among the magnetic material powder and the binder constituting the exterior body 20, the magnetic material powder is a metal magnetic material mainly composed of iron or iron, which has a high saturation magnetic flux density among soft magnetic materials, for example, iron-nickel alloy, iron-. A metal magnetic material having a crystalline composition such as a silicon alloy, an iron-silicon-aluminum alloy, an iron-silicon-chromium alloy, or an amorphous composition such as an iron-silicon-boron alloy can be pulverized or atomized. It is powdered with iron.

The binder coats the particles of the magnetic powder and intervenes between the particles to bond the particles to each other and insulate the flow of eddy currents between the particles, thereby suppressing an increase in the eddy current loss of the exterior body 20. It is something to do.

The binder is preferably an insulating thermosetting resin such as an epoxy resin or a silicone resin, which is mixed with a metal magnetic powder to insulate the particles and bonded by heat treatment after pressure molding. It is preferable because the material can be thermoset to bond the particles to each other.

The exterior body 20 has a bottom surface 21 on the lower side of the third direction 203, a top surface 22 on the opposite side of the bottom surface 21, and a first side surface connecting the bottom surface 21 and the top surface 22 on the front side of the first direction 201. 23, the second side surface 24 on the opposite side of the first side surface 23, the third side surface 25 connecting the first side surface 23 and the second side surface 24 on the back side of the second direction 202, and the opposite of the third side surface 25. It has a fourth side surface 26 in which the first side surface 23 and the second side surface 24 are connected to each other on the side, and in the present embodiment, the external dimensions of the exterior body 20 are approximately 4 of 4.0 mm × 4.0 mm × 2.6 mm. It has a prismatic shape.

The external electrode 30 is connected to a conductor portion 10 embedded inside the exterior body 20, and is exposed to the outside of the exterior body 20 from each of the first side surface 23 and the second side surface 24 of the exterior body 20, and is an external circuit. Used for connection with (not shown).

The external electrode 30 is made of a metal plate 11 such as a copper material, and in the present embodiment, a copper plate having a thickness of 0.15 mm and a width dimension of 2.4 mm is formed, and the width direction thereof is along the second direction 202. It is exposed to the outside of the exterior body 20 in the orientation, and is bent along the bottom surface 21 from the first side surface 23 and the bottom surface 21 from the second side surface 24 to be processed into a surface mount type external electrode 30.

The conductor portion 10 is made of a metal plate 11 such as a linearly stretched copper material, and in the present embodiment, a copper plate having a thickness of 0.15 mm and a width dimension of 2.4 mm is placed in the direction of the first direction 201. It is linearly stretched to a length of 2.0 mm.

The conductor portion 10 is bent in a bellows fold in the width direction (second direction 202).

Here, folding in a bellows fold in the width direction means that, as shown in FIG. 3, mountain folds and valley folds, or valley folds and mountain folds are alternately repeated in the width direction of the conductor portion 10, and the width of the conductor portion 10 is bent. It means that it is bent so as to be zigzag in the direction.

In the example shown in FIGS. 1 to 4, the conductor portion 10 is formed by dividing a metal plate 11 having a width dimension of 2.4 mm into four evenly with a width dimension of 0.6 mm and bending it into a bellows fold. It is linearly stretched to a length of 2.0 mm.

As described above, the inductor 100 of this embodiment is configured.

According to the inductor 100 of the present embodiment described above, the conductor portion 10 is bent in a bellows shape in the width direction according to the above configuration, so that the metal plate 11 forming the conductor portion 10 has a flat plate shape as compared with the case where the conductor portion 10 is formed in a flat plate shape. The magnetic path length of the magnetic flux orbiting around the conductor portion 10 can be shortened, and the effect of improving the magnetic efficiency can be obtained.

The fact that this magnetic path length can be shortened will be described in more detail. Assuming that the shortest magnetic path length is the outer peripheral dimension of the conductor portion 10, the conductor portion 10 has a metal plate 11 having a flat conductor portion as in a conventional inductor and an inductor 100 in the present embodiment. A metal plate 11 bent in a bellows fold in the width direction is compared.

In the case of the conventional inductor, the width dimension of the metal plate 11 is 2.4 mm and the thickness dimension is 0.15 mm, so that the outer peripheral dimension of the conductor portion is twice the width dimension of 2.4 mm and the thickness dimension of 0.15 mm. The total dimension of the doubles is 5.1 mm.

On the other hand, in the conductor portion 10 of the present embodiment, the width dimension of the metal plate 11 is twice equal to 0.6 mm, which is evenly divided into four, and the thickness dimension of four metal plates 11 (0.15 mm). (4 times) The total dimension of 0.6 mm is 2.4 mm. Compared to the conventional inductor, the inductor 100 of this embodiment has the outer peripheral dimension of the conductor portion 10, that is, the shortest magnetic path length. It can be shortened from 1 mm to 2.4 mm.

Since the magnetic permeability of the inductor is inversely proportional to the magnetic path length, the magnetic permeability increases as the magnetic path length becomes shorter, the magnetic efficiency of the inductor 100 can be improved, and the inductor 100 can be made smaller. Is something that can be done.

In the present embodiment, as shown in FIGS. 2 and 3, it is preferable that the metal plate 11 of the conductor portion 10 is laminated in the width direction of the conductor portion 10 in the conductor portion 10. Laminating in the width direction of the conductor portion 10 means that the conductor portions 10 are bent in a bellows fold and are close to each other until the adjacent metal plates 11 come into contact with each other.

As a result, the magnetic path length can be shortened, and the magnetic efficiency of the inductor 100 can be further improved.

In this case, it is preferable to have an insulating layer (not shown) on at least the laminated surface 12 of the conductor portion 10.

The laminated surface 12 means the surface of the metal plate 11 in contact with the laminated surface 12.

Further, for this insulating layer, for example, a technique such as transfer of an insulating resin such as polyurethane resin, polyester resin, enamel resin, or polyamide-imide resin to a portion to be a laminated surface 12 with a desired thickness of 5 to 50 μm is applied. It was applied using and cured by heat treatment.

As a result, even if the metal plates 11 that are bent in a bellows fold and are adjacent to each other come into contact with each other, they are insulated by the insulating layer, so that the influence of the skin effect is suppressed even if the current energizing the inductor 100 is a high frequency current. You can get the effect that you can.

The insulating layer may be interposed at least in the laminated surface 12, but may have an insulating layer so as to cover the entire conductor portion 10.

Further, in the present embodiment, the conductor portion 10 and the external electrode 30 can be integrally formed via the connecting portion 40.

The connecting portion 40 is a single metal plate 11, and is formed by integrally forming a conductor portion 10, a connecting portion 40 connected to both sides of the conductor portion 10, and an external electrode 30 connected to the connecting portion 40. be.

The connecting portion 40 is plastically deformed between the conductor portion 10 and the external electrode 30 by bending the conductor portion 10 into a bellows fold to connect the conductor portion 10 and the external electrode 30.

As a result, the connection between the conductor portion 10 and the external electrode 30 can be omitted, and there is no risk that the welded portion will come off as compared with the case where the conductor portion 10 and the external electrode 30 are connected by welding or the like, and the conductor The effect of improving the connection reliability between the unit 10 and the external electrode 30 can be obtained.

In this case, the connecting portion 40 has a first main surface 41 on the upper side of the third direction 203 and a second main surface 42 on the lower side of the third direction 203 on the back side of the first main surface 41. It is preferable that either one of the 41 and the second main surface 42, or both the first main surface 41 and the second main surface 42, have a recess 43 extending along the width direction of the conductor portion 10.

When the conductor portion 10 is bent into a bellows fold, the concave portion 43 has a convex portion extending along the width direction of the conductor portion 10 provided in the holding mold for holding the metal plate 11 and has an external electrode of the connecting portion 40. It is formed when it is pressed against the edge portion on the 30 side until it bites into it.

As a result, when the conductor portion 10 is bent in a bellows fold, it is possible to suppress the plastic deformation of the connecting portion 40 from extending to the external electrode 30, and it is possible to suppress the deterioration of the flatness of the external electrode 30. It is possible to obtain the effect curing that it is possible to suppress the deterioration of the connection reliability between the external electrode 30 and the external circuit.

The depth dimension of the recess 43 is not particularly limited, but a depth of about 5 to 20 μm is preferable, and if it is smaller than 5 μm, the holding force for holding the metal plate 11 is weakened, which is not preferable, and is more than 20 μm. If it is large, the influence that the cross-sectional area of the metal plate 11 becomes small becomes large, which is not preferable. It is more preferably 10 to 15 μm.

Next, the manufacturing method of the inductor 100 of the present embodiment described above will be described with reference to FIGS. 5 to 8.

First, the conductor portion forming step for forming the conductor portion 10 will be described.

The conductor portion forming step includes a metal plate preparing step of preparing a linearly stretched metal plate 11 and a bent conductor portion forming step of bending the metal plate 11 into a bellows fold in the width direction.

Among these, in the metal plate preparation step, as shown in FIG. 5, a linearly stretched metal plate 11 is prepared.

In this case, the metal plate 11 is a copper plate having a thickness of 0.15 m and a width dimension of 2.4 mm, which is previously connected to the conductor portion 10, the connecting portions 40 connected to both sides of the conductor portion 10, and the connecting portion. The length may be the sum of the dimensions of the external electrodes 30 to be connected, and it is preferable to prepare a metal plate 11 in which the conductor portion 10, the connecting portion 40, and the external electrode 30 are integrated.

Here, FIG. 5 shows an imaginary line of a bending line when the conductor portion 10 is bent into a bellows fold in the middle portion in the extending direction of the metal plate 11 when viewed from the upper side of the third direction 203. The bent line 13 indicated by the alternate long and short dash line is a mountain fold line, and the bent line 14 indicated by the alternate long and short dash line indicates a valley fold line.

As described above, in the bending lines 13 and 14, mountain fold lines and valley fold lines are alternately arranged along the linear stretching direction of the metal plate 11.

Next, in the folding conductor portion forming step, as shown in FIG. 6, the bending line 13 is bent into a mountain fold and the bending line 14 is bent into a valley fold along the bending lines 13 and 14 by press working, and the metal is formed. The plate 11 is bent in a bellows fold along the stretching direction.

In this case, as the internal angle between the bent adjacent metal plates 11 decreases from 180 °, the interval between the mountain fold and the valley fold gradually narrows when viewed from the upper side of the third direction 203.

Therefore, it is preferable to bend the internal angles in a plurality of times, for example, 150 °, 120 °, 90 °, so that the internal angles of the adjacent metal plates 11 gradually become smaller.

The example shown in FIG. 6 shows an example in which the internal angles of the folded adjacent metal plates 11 are bent to 90 °.

Next, in the conductor portion forming step, it is preferable to perform the conductor portion compression step after the bent conductor portion forming step.

In the conductor portion compression step, as shown in FIG. 7, the conductor portion 10 is compressed in the width direction of the conductor portion 10 from both sides in the width direction (second direction 202) of the conductor portion 10 by using the compression mold 50. As a result, the metal plates 11 adjacent to each other in the width direction of the conductor portion 10 are laminated.

In this case, it is preferable to perform an insulating layer forming step between the metal plate preparation step and the bent conductor portion forming step.

In this insulating layer forming step, an insulating layer (not shown) is formed on at least the laminated surface 12 of the conductor portion 10 on which the metal plate 11 is laminated. For example, polyurethane resin, polyester resin, enamel resin, or polyamide is formed. An insulating resin such as an imide resin is applied to a portion to be a laminated surface 12 with a desired thickness of 5 to 50 μm by using a technique such as transfer, and is heat-treated to be cured.

The insulating layer may be formed on the entire conductor portion 10.

Here, when the conductor portion 10, the connecting portion 40, and the external electrode 30 are integrally formed by the metal plate 11, the connecting portion 40 has the first main surface 41 and the third direction 203 on the upper side of the third direction 203. It has a second main surface 42 on the lower side and behind the first main surface 41.

Then, in the bending conductor portion forming step and the conductor portion compression step in the conductor portion forming step, the edge portion of the connecting portion 40 on the external electrode 30 side is held by the holding metal from both sides of the first main surface 41 and the second main surface 42. It is preferable to bend the conductor portion 10 into a bellows fold while sandwiching and holding the conductor portion 10 with a mold (not shown).

Further, the conductor portion 10 is placed on the holding surface of either the first main surface 41 side and the second main surface 42 side, or both the first main surface 41 side and the second main surface 42 side of the holding mold. It is more preferable to provide a convex portion (not shown) extended in the width direction and hold the convex portion by a force that bites into the connecting portion 40.

As a result, when the conductor portion 10 is bent in a bellows fold, it is possible to prevent the plastic deformation of the connecting portion 40 from extending to the external electrode 30.

Next, the exterior body forming step is performed.

In the exterior body forming step, as shown in FIG. 8, a magnetic material in which a magnetic material powder and a binder are mixed, a conductor portion 10 and a connecting portion 40 are placed in a cavity 60 of a molding die for molding the exterior body 20. The outer body 20 is obtained by putting the external electrode 30 out of the cavity 60, pressure-molding the magnetic material, and then curing the binder.

Finally, if necessary, the surface of the external electrode 30 is solder-plated, the external electrode is cut to a desired length, and the external electrode 30 is bent. The inductor 100 shown in 2 can be obtained.

According to the above-described method for manufacturing an inductor of the present embodiment, the same action and effect as those described for the above-mentioned inductor 100 of the present embodiment can be obtained by the above-mentioned manufacturing method.

In the present embodiment, the conductor portion 10 is bent in a bellows direction in the width direction and laminated, but as shown in FIG. 9 showing another example of the inductor of the present embodiment, simply, The conductor portion 10 may be bent in a bellows fold in the width direction.

In the example shown in FIG. 9, the conductor portion 10 shown in FIG. 6 is covered with the exterior body 20, and the cross section orthogonal to the linearly extending direction of the conductor portion 10 is seen as in the cross-sectional view of FIG. Yes, it is possible to obtain the same effect as that of the present embodiment described above.

Further, in the present embodiment, the width dimension of the metal plate 11 of the conductor portion 10 and the width dimension of the metal plate 11 of the external electrode 30 are the same, and the cross-sectional area of the conductor portion 10 and the external electrode 30 is the same area. As described above, the cross-sectional area of the conductor portion 10 may be larger than the cross-sectional area of the external electrode 30 in the cross section orthogonal to the stretching direction of the conductor portion 10.

Other examples of such an inductor of this embodiment are shown in FIGS. 10 and 11.

As shown in FIG. 10, in the metal plate preparation step, a metal plate is prepared in which the width dimension of the portion forming the conductor portion 10 is larger than the width dimension of the portion forming the connecting portion 40 and the external electrode 30.

Then, as shown in FIG. 11, the valley fold bending line 14 is also arranged in the connecting portion 40 of the conductor portion 10 and the portion larger than the width dimension of the external electrode 30, and the conductor portion is bent into a bellows fold. In the cross section orthogonal to the stretching direction of 10, the cross-sectional area of the conductor portion 10 is larger than the cross-sectional area of the external electrode 30.

Also in the inductors shown in FIGS. 10 and 11 and the manufacturing method thereof, the same operation and effect as those of the inductor 100 of the present embodiment described above and the manufacturing method thereof can be obtained, and further, the cross-sectional area of the conductor portion 10 is increased. By increasing the size, the DC resistance of the conductor portion 10 can be reduced, and the effect that the loss as an inductor can be reduced can be obtained.

The inductor configuration and the manufacturing method thereof according to the present invention are industrially useful because even an inductor using a linearly stretched conductor can be an inductor with good magnetic efficiency.

10 Conductor 11 Metal plate 12 Laminated surface 13 Folded line 14 Folded line 20 Exterior body 21 Bottom surface 22 Top surface 23 First side surface 24 Second side surface 25 Third side surface 26 Fourth side surface 30 External electrode 40 Connecting part 41 First main surface 42 Second main surface 43 Recess 50 Compression mold 60 Cavity 100 Inductor 201 First direction 202 Second direction 203 Third direction

Claims (8)

It is provided with a conductor portion made of a metal plate and linearly stretched, an exterior body made of a magnetic material covering the conductor portion, and an external electrode connected to the conductor portion and exposed from the exterior body, and the conductor portion is provided in the width direction. The conductor portion and the external electrode are integrally formed via a connecting portion, and the connecting portion has a first main surface and a second main surface on the back side of the first main surface. The first main surface and the second main surface, or both the first main surface and the second main surface, have recesses extending along the width direction of the conductor portion. An inductor characterized by. The inductor according to claim 1, wherein the conductor portion is formed by laminating the metal plates of the conductor portion in the width direction. The inductor according to claim 2, wherein the inductor has an insulating layer on at least the laminated surface of the conductor portion. It is provided with a conductor portion made of a metal plate and linearly stretched, an exterior body made of a magnetic material covering the conductor portion, and an external electrode connected to the conductor portion and exposed from the exterior body, and the conductor portion is provided in the width direction. An inductor characterized in that the cross-sectional area of the conductor portion is larger than the cross-sectional area of the external electrode in a cross section orthogonal to the stretching direction of the conductor portion. It is a method for manufacturing an inductor having a conductor portion made of a metal plate and linearly stretched, an exterior body made of a magnetic material covering the conductor portion, and an external electrode connected to the conductor portion and exposed from the exterior body. The step of forming the conductor portion includes a metal plate preparation step of preparing a linearly stretched metal plate and a bent conductor portion forming step of bending the metal plate in a bellows fold in the width direction. In the preparation step, the metal plate having a length for integrally forming the connecting portion connected to each of the conductor portion and both sides of the conductor portion in the stretching direction and the external electrode connected to the connecting portion is prepared. The connecting portion has a first main surface and a second main surface on the back side of the first main surface, and in the bending conductor portion forming step, the connecting portion is connected to the first main surface and the second main surface. The conductor portion is bent into a bellows fold while being sandwiched and held by a mold from both sides of the main surface, and either one of the first main surface side and the second main surface side, or the first main surface. It is characterized in that a convex portion extending in the width direction of the conductor portion is provided on the holding surface of the mold on both the surface side and the second main surface side, and the convex portion is made to bite into the connecting portion and held . How to manufacture the inductor. The conductor portion forming step is characterized by having a conductor portion compression step of laminating the metal plate of the conductor portion in the width direction by compressing the conductor portion in the width direction after the bending conductor portion forming step. 5. The method for manufacturing an inductor according to claim 5 . The method for manufacturing an inductor according to claim 6 , further comprising an insulating layer forming step of forming an insulating layer on at least a laminated surface of the conductor portion between the metal plate preparation step and the bent conductor portion forming step. The method for manufacturing an inductor according to claim 5 , wherein in the metal plate preparation step, the width dimension of the portion forming the conductor portion is made larger than the width dimension of the connecting portion and the portion forming the external electrode. ..

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