JP2005244041A - Inductance element and its production process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inductance element which can be mounted on the surface of a substrate with no external electrode. <P>SOLUTION: The inductance element 1 comprises a center core 2 having a coil fixing part 2a being applied with a coil 4, and a pair of side cores 3 provided on the opposite sides of the coil fixing part 2a of the center core 2 to project therefrom like a jaw. Opposite end parts 4b of the coil 4 are extended from the same side of the side face 3b of both side cores 3 to the opposite sides of the coil fixing part 2a, a protective coating 5 is provided on the outer circumference of the winding part 4a of the coil 4 being applied to the coil fixing part 2a, and the part 4b of the coil 4 extended from the winding part 4a is folded along the outer surface of the side core 3. With such an arrangement, circuit of the circuit board can be electrically connected with the opposite end parts 4b of the coil 4 directly. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an inductance element suitable for a choke coil, an inductor, and the like, and a method for manufacturing the inductance element.

In DC / DC converters mounted on portable electronic devices such as notebook computers and video cameras, inductance elements such as choke coils are mounted on the surface of a substrate.
In order to electrically connect the coil to the wiring (circuit) formed on the substrate, this type of inductance element is provided with an external electrode for SMT (surface mounting technology), and the coil and the external electrode are welded. Etc. (see, for example, Patent Documents 1 and 2).
FIG. 7 shows an example of a conventional inductance element. In FIG. 7, reference numeral 101 denotes an inductance element, reference numeral 102 denotes a drum core having a T-shaped longitudinal section, reference numeral 103 denotes a pot core, reference numeral 104 denotes a coil, reference numeral 105 denotes a frame electrode serving as an external electrode, and reference numeral 106 denotes a coil 104 and frame electrode 105. It is the welding part 106. In this inductance element 101, the coil 104 is wound around the shaft portion 102 a of the drum core 102 and is surrounded by the flange portion 102 b of the drum core 102 and the pot core 103. The drum core 102 and the pot core 103 form a closed magnetic path. Further, a part of the frame electrode 105 is inside the pot core 103, a part is exposed to the outer surface of the pot core 103, and extends to the bottom surface 103 b of the pot core 103. The end 104 b of the coil 104 is welded to the frame electrode 105 at the end edge 103 a of the pot core 103.
JP 2003-109824 A JP 2003-168607 A

  However, in the inductance element 101 as described above, since the gap between the flange portion 102b of the drum core 102 and the end edge 103a of the pot core 103 is narrow, it is difficult to weld the coil 104 and the frame electrode 105. For example, a laser is used. However, the manufacturing cost is high. In addition, a short prevention frame is required, and coil welding requires peeling forming of a coil lead wire (for example, a flat wire), which increases costs. In addition, there is a risk that variations in inductance will increase.

  This invention is made | formed in view of the said situation, and makes it a subject to provide the manufacturing method of an inductance element which can be mounted in the board | substrate surface etc., without using an external electrode.

In order to solve the above problems, the present invention provides a center core having a coil mounting portion around which a coil is wound, and is provided on both sides of the coil mounting portion of the center core and protrudes in a hook shape from the coil mounting portion. A pair of side cores having a shape, both end portions of the coil extending from the same side of the side surfaces of both side cores to both sides of the coil mounting portion, and wound around the coil mounting portion of the coil. Provided is an inductance element in which a protective coating is provided on an outer periphery of a winding portion, and an extending portion that is a portion extending from the winding portion of the coil is folded along an outer surface of a side core. To do.
In the inductance element, it is preferable to use a magnetic wire having magnetic plating on the outer periphery as a conducting wire constituting the coil.
The protective coating is preferably formed from a magnetic powder coated with a thermoplastic resin or a mixture of a thermoplastic resin and a magnetic powder.

  In the present invention, a coil is wound around the coil mounting portion of the center core, and side cores having a shape protruding from the coil mounting portion are mounted on both sides of the coil mounting portion of the center core. Each part extends from the same side of both side cores to both sides of the coil mounting part, and a protective coating is provided on the outer periphery of the winding part that is wound around the coil mounting part of the coil. Provided is a method of manufacturing an inductance element, wherein an extended portion that is a portion extended from a winding portion is folded along an outer surface of a side core.

According to the present invention, since the extending portion extending to both ends of the coil is folded along the outer surface of the side core, a wiring (circuit) can be directly connected to the extending portion. Therefore, the external electrode can be omitted and the manufacturing process can be simplified.
When a magnetic wire with magnetic plating on the outer periphery is used as the conducting wire that constitutes the coil, the magnetic flux exposed on the outer periphery of the coil is magnetically shielded so that the side cores have a substantially closed magnetic circuit structure, thus reducing leakage flux Thus, the characteristics can be improved.
When the protective coating is made of magnetic powder coated with thermoplastic resin or a mixture of thermoplastic resin and magnetic powder, the magnetic flux (magnetic material) contained in the protective coating reduces the leakage flux of the inductance element. The closed magnetic circuit characteristics can be improved.

The present invention will be described below with reference to the drawings based on the best mode.
1 to 3 are drawings showing an embodiment of the inductance element of the present invention. FIG. 1A is a one-side cutaway plan view of an inductance element according to the present embodiment, FIG. 1B is a one-side sectional front view, and FIG. 2 is an external perspective view. The right side of FIG. 1A shows a state in which the coil is exposed by cutting out the protective coating on the front side of the drawing. FIG. 3 is an exploded perspective view showing a core and a coil in the inductance element of FIG.
4 to 6 are diagrams illustrating a manufacturing process of the inductance element of FIG. 4 is a perspective view illustrating a state in which the coil is wound around the center core, FIG. 5 is a perspective view illustrating a state in which side cores are mounted on both sides of the center core around which the coil is wound, and FIG. It is a perspective view which illustrates the state where protective covering was provided.
As shown in FIGS. 1 to 3, the inductance element 1 of this embodiment includes a coil 4, a center core 2 having a coil mounting portion 2 a around which the coil 4 is wound, and the coil mounting of the center core 2. A pair of side cores provided on both sides of the portion 2a.

  Here, the center core 2 has a rectangular flat plate shape, and the coil mounting portion 2a is provided in the central portion excluding both end portions 2b of the center core 2. Here, the width of the coil mounting portion 2a is about twice the width of the flat wire, and it is possible to mount a coil formed so that the flat wire wound in an overlapping manner is arranged in two rows in the edge direction. Yes. Both end portions 2b of the center core 2 are side core mounting portions to which the side core 3 is mounted. In order to reduce the height (thinner) of the inductance element 1, the center core 2 is preferably flat. The center core 2 preferably has a high magnetic permeability in order to obtain a high inductance. Examples of the core material having high magnetic permeability include permalloy and iron.

The side core 3 has a hole 3a (here, a through hole having a rectangular cross section) into which both end portions 2b of the center core 2 are inserted. The side core 3 is shaped such that the side core 3 protrudes from the coil mounting portion 2 a of the center core 2 in a hook shape by mounting the side core 3 on both ends 2 b of the center core 2. Here, the side core 3 is formed in a square frame shape surrounding the hole 3a. The side core 3 is preferably made of a magnetic material having a high electric resistance such as ferrite in order to obtain insulation from the extended portion 4b of the coil 4 and an external circuit.
The center core 2 and the side core 3 are preferably fixed to each other using an adhesive or the like.

As the coil 4, for example, an air-core coil in which a rectangular copper wire is α-wound (a winding method in which both ends of a conductive wire wound in an overlapping manner come out of the winding) can be used. Both ends of the coil 4 are folded back in a direction perpendicular to the winding direction of the winding portion 4a, and are extended so as to protrude outward from the winding portion 4a. That is, the coil 4 includes a winding portion 4a that is a portion wound around the coil mounting portion 2a of the center core 2 and an extending portion 4b that is a portion extending from the winding portion 4a. The number of turns of the coil 4 is not particularly limited, and is preferably set so as to obtain desired characteristics.
Although the conducting wire which comprises the coil 4 may be a round wire etc., since a space factor can be made high, a strip | belt-shaped rectangular wire is preferable. Moreover, it is preferable that it is a magnetic wire which has magnetic plating (plating of magnetic substances, such as iron) in outer periphery. Particularly preferred is a flat magnetic wire.

A protective coating 5 is provided on the outer periphery of the winding portion 4 a of the coil 4. The protective coating 5 is preferably made of an electrically insulating synthetic resin such as a silicone resin, an epoxy resin, or a urethane resin. Thereby, the folding | returning part 4e between the coil | winding part 4a and the extension part 4b is covered with the protective coating 5, and the winding | winding deviation of a conducting wire and the damage by external force can be suppressed. Moreover, short-circuiting of the coil 4 can be suppressed by insulatingly covering the winding portion 4a. In addition, it is preferable that the resin is an elastomer such as a silicone elastomer in terms of impact resistance, shape followability to the substrate surface, and the like.
Further, the protective coating 5 may contain a magnetic material. In this case, the magnetic flux contained in the protective coating can reduce the leakage magnetic flux of the inductance element and improve the closed magnetic circuit characteristics. The protective coating 5 containing a magnetic body can be formed from, for example, a magnetic powder coated with a thermoplastic resin, or a mixture of a thermoplastic resin and a magnetic powder. As the magnetic material to be blended in the protective coating 5, it is preferable to use magnetic powder having electrical insulation properties such as ferrite. This eliminates the possibility of short circuit even if the magnetic material in the protective coating 5 is exposed. Examples of the thermoplastic resin include an epoxy resin, an acrylic resin, polyurethane, and enamel. The thermoplastic resin is preferably a resin that melts when heated to about 200 to 250 ° C., for example. By using the thermoplastic resin together with the magnetic powder, the magnetic powder can be fused with the molten thermoplastic resin.

  The coil 4 can be mounted in a state where the coil 4 is wound around the coil mounting portion 2a by passing the center core 2 through the hollow portion 4d of the winding portion 4a. The extending portion 4b of the coil 4 extends from the same side (upper side in FIG. 1B) of the side surface 3b of the side core 3. The extension 4b is folded along the outer surface of the side core 3, and both ends 4c of the coil 4 reach the side opposite to the extension start side of the extension 4b (the lower side in FIG. 1B). ing.

  In order to mount the inductance element 1 on the substrate, the inductance element 1 is disposed so that both ends 4c of the coil 4 face the substrate 6 side as shown in FIG. The portion 4b and the wiring (electronic circuit etc.) of the substrate 6 are electrically connected. The coil 4 and the substrate 6 can be connected by using, for example, solder, lead-free solder, a conductive adhesive, a bonding wire, or the like.

Next, a method for manufacturing the inductance element 1 according to this embodiment will be described. In this manufacturing method, first, as shown in FIG. 4, the center core 2 is inserted into the hollow portion 4 d of the coil 4, and the winding portion 4 a of the coil 4 is attached to the coil attachment portion 2 a of the center core 2.
Next, as shown in FIG. 5, the side cores 3 are mounted on both sides of the coil mounting portion 2 a of the center core 2. Thereby, the extension part 4b of the coil 4 will be in the state extended from the same side (upper side in FIG. 5) of the side surface 3b of both side cores 3, respectively.

Next, the coil 4 is surrounded by a rubber mold (not shown) and injected with resin, magnetic powder coated with thermoplastic resin, or a mixture of thermoplastic resin and magnetic powder, as shown in FIG. Further, a protective coating 5 is formed on the outer periphery of the winding portion 4 a of the coil 4. When the protective coating 5 is formed, the extended portion 4b is exposed outside the rubber mold, the folded portion 4e of the coil 4 is covered with the protective coating 5, and the extended portion 4b is exposed outside the protective coating 5. It is good to do so.
When the protective coating 5 is formed from magnetic powder coated with a thermoplastic resin, the magnetic powder coated with the thermoplastic resin is poured into a mold, and then heated to melt the thermoplastic resin so that the magnetic powders Can be self-fused.
When the protective coating 5 is formed from a mixture of a thermoplastic resin and magnetic powder, the mixture of the thermoplastic resin and magnetic powder is poured into a mold and then heated to melt the thermoplastic resin so that the magnetic powders Can be fused.
Further, by folding the extension 4b of the coil 4 along the outer surface of the side core 3, the inductance element 1 as shown in FIGS. 1 and 2 is obtained.

In the inductance element 1 according to the present embodiment, since the extended portions 4b extending to both ends of the coil 4 are extended and folded along the outer surface of the side core 3, a circuit is directly connected to the extended portion 4b. Therefore, it is suitable as a surface mount type inductance element. External electrodes for connection with the wiring of the substrate can be omitted, and the manufacturing process can be simplified. Since there is no welded portion connecting the coil and the external electrode, it is not necessary to use a fine welding technique such as laser spot welding, and the manufacturing cost can be reduced. Since the conducting wire of the coil 4 is a flat wire, the width of the portion exposed as the extending portion 4b is wide, and it is easy to connect to the substrate side wiring.
According to the inductance element manufacturing method of the present embodiment, no compacting or pressure forming is required for forming the core, and a small element can be easily manufactured by assembling the core and the air-core coil.

Since the protective coating 5 is provided on the outer periphery of the winding portion 4a of the coil 4, the folded portion 4e between the winding portion 4a and the extension portion 4b is covered with the protective coating 5, and winding of the lead wire and external force It is possible to suppress damage caused by. Moreover, short-circuiting of the coil 4 can be suppressed by insulatingly covering the winding portion 4a.
When a magnetic wire is used as the conductive wire constituting the coil 4, the magnetic plating exposed on the outer periphery of the coil 4 is magnetically shielded so that the side cores 3 and 3 have a substantially closed magnetic circuit structure. It can be reduced to improve the characteristics.
When the protective coating 5 contains magnetic powder, the closed magnetic circuit characteristics of the inductance element 1 can be improved.

  The inductance element of the present invention can be used as a choke coil or an inductor, and is suitable for surface mounting on a substrate. The inductance element of the present invention can also constitute a transformer by providing a plurality of coils. Further, the use of the inductance element of the present invention is not limited to the case where it is mounted on a substrate, and can be used by being connected to a conducting wire, for example.

It is (a) one side notch top view which shows an example of the inductance element of this invention, (b) one side sectional front view. It is an external appearance perspective view of the inductance element of FIG. It is a disassembled perspective view which shows the core and coil in the inductance element of FIG. FIG. 2 is a diagram illustrating a manufacturing process of the inductance element of FIG. 1, and is a perspective view illustrating a state where a coil is wound around a center core. FIG. 2 is a diagram illustrating a manufacturing process of the inductance element of FIG. 1, and is a perspective view illustrating a state in which side cores are mounted on both sides of a center core around which a coil is wound. FIG. 2 is a diagram illustrating a manufacturing process of the inductance element of FIG. 1, and is a perspective view illustrating a state in which a protective coating is provided on the outer periphery of the coil. It is a perspective view which shows an example of the conventional inductance element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Inductance element, 2 ... Center core, 2a ... Coil mounting part, 3 ... Side core, 3b ... One side surface of a side core, 4 ... Coil, 4a ... Winding part, 4b ... End part (extension part) of a coil, 4c ... coil ends, 5 ... protective coating.

Claims (4)

  A center core having a coil mounting portion around which a coil is wound, and a pair of side cores that are provided on both sides of the coil mounting portion of the center core and project from the coil mounting portion in a bowl shape, Both end portions of the coil are extended from the same side of both side cores to both sides of the coil mounting portion, and a protective coating is provided on the outer periphery of the winding portion which is a portion wound around the coil mounting portion of the coil. An inductance element, wherein an extended portion that is a portion extended from the winding portion of the coil is folded along an outer surface of the side core.   The inductance element according to claim 1, wherein the conductive wire constituting the coil is a magnetic wire having magnetic plating on an outer periphery.   The inductance element according to claim 1, wherein the protective coating is formed of magnetic powder coated with a thermoplastic resin or a mixture of thermoplastic resin and magnetic powder.   A coil is wound around the coil mounting portion of the center core, side cores that protrude from the coil mounting portion in a hook shape are respectively mounted on both sides of the coil mounting portion of the center core, and both end portions of the coil are respectively connected to both side cores. Extending from the same side of the coil to both sides of the coil mounting portion, providing a protective coating on the outer periphery of the winding portion that is the portion wound around the coil mounting portion of the coil, and extending from the winding portion of the coil A method of manufacturing an inductance element, wherein an extended portion as a protruding portion is folded along an outer surface of a side core.

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