JP2013149814A - Surface mounting inductor and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small surface mounting inductor advantageous for high density mounting on a circuit board, and to provide a manufacturing method therefor.SOLUTION: The surface mounting inductor includes a coil formed by winding a wire, a core internally sealing the coil principally consisting of a magnetic powder and a resin, and an L-shaped external electrode formed on the surface of the core by using a conductive paste. The core is formed to have an upper surface, a bottom face, and a pair of end faces narrower than the central part of the core and facing each other. The core is formed so that the ends of the coil are exposed, respectively, to the surface of end faces facing each other. An external electrode is formed by coating a part of the end face and the bottom face with a conductive paste by using a print system, and connecting electrically with the coil end. The external electrode is formed narrower than the central part of the core, and not to reach the upper surface of the core.

Description

  The present invention relates to a small surface-mount inductor and a manufacturing method thereof.

  2. Description of the Related Art Surface mount inductors that enclose a coil around which a wire is wound in a core are widely used. With recent downsizing and thinning of electronic devices such as mobile phones, electronic components such as surface mount inductors are also required to be downsized and low profiled. Therefore, the applicant described in Patent Document 1 filed earlier, a small surface-mount inductor using a coil and a pre-formed tablet in which a rectangular conductor is wound in a spiral shape so that both ends thereof are drawn to the outer periphery. And the manufacturing method was proposed.

  The surface-mount inductor disclosed in Patent Document 1 is set in a molding die with a coil wound with a flat conducting wire placed on a tablet, and compression-molded above the softening point of the tablet to obtain a rectangular parallelepiped shaped body. . External electrodes are formed from both side surfaces of the molded body using a method such as dipping. Therefore, as shown in FIG. 13, the external electrode 103 is formed over the five surfaces of the molded body 102.

JP 2010-245473 A

  However, as electronic devices are further reduced in size and increased in current, high-density mounting of electronic components on a circuit board is required. In the surface mount inductor as in the cited document 1, the width of the external electrode 103 is larger than the width of the rectangular parallelepiped shaped body 102 by the thickness of the electrode film, and the electrodes are formed up to the side surface. Therefore, it is necessary to provide a certain distance so that the external electrodes do not come into contact with each other, which is a disadvantageous structure for high-density mounting. And in the surface mount inductor of the cited reference 1, there was a possibility that the external electrode formed on the upper surface would contact the metal shield plate and short-circuit.

  Accordingly, an object of the present invention is to provide a small surface-mount inductor that is advantageous for high-density mounting on a circuit board.

  In order to solve the above-mentioned problems, a surface mount inductor according to the present invention includes a coil wound with a wire, a core portion mainly enclosing a coil made of magnetic powder and resin, and a conductive surface on the surface of the core portion. And an L-shaped external electrode formed using a paste. The core part is formed in a shape having an upper surface, a bottom surface, and a pair of opposing end surfaces having a width narrower than that of the central part of the core part. At this time, the core portion is formed so that each end portion of the coil is exposed on the surface of the opposing end face. A conductive paste is applied to a part of the end face and the bottom face using a printing method and electrically connected to the end of the coil to form an external electrode. The external electrode has a narrower width than the central portion of the core portion and is formed so as not to reach the upper surface of the core portion.

  In the surface mount inductor according to the present invention, the external electrodes are formed so as to be narrower than the width of the core portion, and are formed so as not to reach the top surface.

  Since the surface mount inductor of the present invention can increase the area of the core and winding by the thickness of the electrode other than the mounting surface as compared with the conventional surface mount inductor, the L value, DC resistance, DC superposition characteristics, etc. This is advantageous in terms of characteristics. Alternatively, it is possible to reduce the size and height by the thickness of the electrode. Since the electrode area is smaller than that of a conventional surface mount inductor, eddy current due to leakage magnetic flux hardly occurs, which is advantageous in terms of circuit efficiency.

It is a perspective view of the coil used in the Example of this invention. It is a perspective view of the core part of the 1st Example of the present invention. It is a top view of the core part of the 1st Example of the present invention. 1 is a perspective view of a surface-mount inductor according to a first embodiment of the present invention. It is a figure explaining the external electrode of the surface mount inductor of the 1st Example of this invention. It is a perspective view of other examples of the surface mount inductor of the present invention. It is a perspective view of other examples of the surface mount inductor of the present invention. It is a perspective view of the core part of the 2nd Example of this invention. It is a side view of the core part of the 2nd Example of this invention. It is a perspective view of the surface mount inductor of the 2nd example of the present invention. It is a perspective view of other examples of the surface mount inductor of the present invention. It is a perspective view of other examples of the surface mount inductor of the present invention. It is a perspective view of the conventional surface mount inductor.

  Embodiments of a surface mount inductor and a method for manufacturing the same according to the present invention will be described below with reference to the drawings.

(First embodiment)
A first embodiment of the surface-mount inductor according to the present invention will be described with reference to FIGS. FIG. 1 is a perspective view of a coil used in the following embodiments. 2 and 3 show the core portion of the first embodiment of the present invention, FIG. 2 is a perspective view, and FIG. 3 is a top view. FIG. 4 shows a perspective view from the bottom side of the surface-mount inductor according to the first embodiment of the present invention. FIG. 5 is a diagram for explaining the external electrodes of the surface-mount inductor according to the first embodiment of the present invention.

  First, as shown in FIG. 1, a coil 1 was obtained by winding a rectangular conductive wire having a self-bonding film around two stages of outer and outer windings using a winding core having an oval cross section. The coil 1 was formed in a shape having a winding part 1a around which a wire was wound and both end parts 1b drawn out so as to face each other with the winding part 1a interposed therebetween.

  Next, as shown in FIG. 2, the core part 2 was formed using a compression molding method so as to enclose the coil 1 with a sealing material obtained by mixing iron-based metal magnetic powder and an epoxy resin. . At this time, it forms so that the edge part 1b of the coil 1 may be exposed on the surface of the both end surfaces which the core part 2 opposes. As shown in FIG. 3, in this embodiment, the core portion 2 is formed in an octagon shape so that the width W <b> 2 of the end surface of the core portion 2 is smaller than the width W <b> 1 of the central portion of the core portion 2.

  Next, sandblasting is performed to remove the deburring and the coating on the exposed surfaces of both end portions 1b, and then a conductive paste is transferred onto a part of the end surface and bottom surface of the core portion 2 and cured. As a result, the conductive paste and the internal coil 1 are conducted. Finally, a plating process is performed to form a plating layer on the surface of the conductor paste, and the L-shaped external electrode 3 is formed to obtain a surface mount inductor as shown in FIG. At this time, the external electrode 3 is formed such that the width W3 of the external electrode 3 is narrower than the width W1 of the central portion of the core portion 2 as shown in FIG. Further, the conductive paste is transferred by a printing method so as not to reach the upper surface of the core part 2, and the external electrode 3 is formed so as not to reach the upper surface of the core part 2. Note that the electrode formed by plating may be formed by appropriately selecting one or a plurality of electrodes such as Ni, Sn, Cu, Au, and Pd.

  Here, another embodiment similar to the first embodiment is shown. 6 and 7 are perspective views of other embodiments of the surface mount inductor according to the present invention. Even if the core part 2 is formed in a cross shape as shown in FIG. 6 or a rounded rectangle as shown in FIG. 7, the same effect as the octagonal core part of the first embodiment is obtained.

(Second embodiment)
A second embodiment of the surface-mount inductor according to the present invention will be described with reference to FIGS. 8 and 9 show the core part of the second embodiment of the present invention. FIG. 8 is a perspective view and FIG. 9 is a side view. FIG. 10 is a perspective view from the upper surface side of the surface mount inductor according to the second embodiment of the present invention. In the second embodiment, the coil and the sealing material used in the first embodiment are used. The description of the same part as the first embodiment is omitted.

  First, the core portion 12 was formed using a compression molding method so as to enclose the coil with a sealing material. At this time, it forms so that the edge part 1b of a coil may be exposed on the surface of the both end surfaces which the core part 12 opposes. In this embodiment, the core portion 12 is formed in an octagonal shape as in the first embodiment, and the height H2 of the end face of the core portion 12 is lower than the height H1 of the center portion as shown in FIG. Thus, the upper surface was formed in a taper shape.

  Next, after sandblasting is performed to remove the deburring and the coating on the exposed surfaces of both end portions 1b, a conductive paste is applied to the end surface and part of the bottom surface of the core portion 12 by roller printing and cured. As a result, the conductive paste and the internal coil are conducted. Finally, a plating process is performed to form a plating layer on the surface of the conductive paste, and an L-shaped external electrode 13 is formed to obtain a surface mount inductor as shown in FIG. In the surface mount inductor of the second embodiment, the upper surface of the core portion is formed in a convex shape in advance, and the conductive paste is applied by a printing method. The electrode can be formed without reaching the upper surface of the core portion.

  Here, another embodiment similar to the second embodiment is shown. 11 and 12 are perspective views of other embodiments of the surface-mount inductor according to the present invention. Even if the core portion 12 is formed in a shape having a step on the upper surface of the core portion 12 as shown in FIGS. 11 and 12, the same effect as the core portion having the tapered upper surface of the second embodiment can be obtained.

  In the said Example, the iron-type metal magnetic powder was used for the magnetic powder as a sealing material, and the epoxy resin was used for the binder. By using iron-based metal magnetic powder, a surface-mount inductor having excellent DC superposition characteristics can be produced. However, the present invention is not limited thereto, and for example, ferrite magnetic powder or the like as magnetic powder, or magnetic powder subjected to surface modification such as insulation film formation or surface oxidation may be used. In addition, an inorganic substance such as glass powder may be added. A thermosetting resin such as polyimide resin or phenol resin, a thermoplastic resin such as polyethylene resin or polyamide resin, an inorganic binder, or the like may be used as the binder.

  In the above embodiment, an oval outer and outer coil is created using a flat wire, but not limited to this, a circular, fan-shaped, semi-circular, trapezoidal, polygonal shape, or a combination of them is used. It may be used. Further, a round wire or the like may be adopted instead of the flat wire, and an aligned winding or an edgewise winding may be used instead of the outer and outer windings.

  In the above embodiment, the core is created by using the compression molding method, which is one of the plastic molding methods. However, the core is not limited to this, and may be created by using a molding method such as a compacting method.

  In the above embodiment, sand blasting was used as a method for deburring and peeling the coating on the coil end surface. However, the present invention is not limited to this, and it is possible to use a coating peeling method such as deburring by barrel polishing or mechanical peeling. is there. Moreover, you may peel the coating | film | coat of an edge part previously before forming a core part.

1: Coil, 1a: Winding part, 1b: End part 2, 12: Core part 3, 13: External electrode

Claims (8)

A coil wound with a wire,
A core portion that encloses the coil mainly made of magnetic powder and resin,
An L-shaped external electrode formed on the surface of the core portion using a conductive paste,
The core portion is formed in a shape having a top surface, a bottom surface, and a pair of opposing end surfaces having a width narrower than the central portion of the core portion,
Each of the ends of the coil is exposed on the surface of the opposing end face,
A conductive paste is applied to the end surface and a part of the bottom surface using a printing method, and electrically connected to the end of the coil to form the external electrode,
At this time, the external electrode is formed so as to have a width narrower than that of the central portion of the core portion and not to reach the upper surface of the core portion. In the core part,
The surface-mount inductor according to claim 1, wherein the end face is formed in a shape in which four corners are cut so that a width of the end face is narrower than a center portion. In the core part,
3. The surface mount inductor according to claim 2, wherein the shape viewed from the upper surface is one of an octagon, a cross-shaped, and a rounded rectangle. In the core part,
4. The surface mount inductor according to claim 1, wherein the upper surface is formed in a convex shape, and the height of the end surface is lower than the height of the central portion of the core portion. In the core part,
The surface-mount inductor according to claim 4, wherein the upper surface has a tapered shape or a stepped shape. Winding a wire to form a coil;
A step of preparing a sealing material mainly composed of magnetic powder and resin;
Forming a core portion using the sealing material so as to enclose the coil therein;
Applying an electrically conductive paste to the end surface and a part of the bottom surface using a printing method to form an L-shaped external electrode by electrically connecting to the end of the coil, and
In the step of forming the core portion, the core portion is formed into a shape having a top surface, a bottom surface, and a pair of opposing end surfaces having a width narrower than that of the central portion of the core portion. Seal so that each end of the coil is exposed,
In the step of forming the external electrode, the external electrode is formed so as to have a width narrower than that of the central portion of the core portion and not to reach the upper surface of the core portion. In the step of forming the core part,
The method for manufacturing a surface mount inductor according to claim 6, wherein the end face is formed in a shape in which four corners are cut so that a width of the end face is narrower than a central portion. In the step of forming the core part,
8. The surface-mount inductor according to claim 6, wherein the upper surface is formed in a convex shape so that the height of the end surface is lower than the height of the central portion of the core portion. 9.

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