KR102022272B1 - Surface mount inductor and method of manufacturing the same - Google Patents

Abstract

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a small surface-mount inductor which is advantageous for high-density mounting on a circuit board and a manufacturing method thereof.
[Solution] The surface mount inductor of the present invention has an L-shaped coil formed by using a conductive paste on the surface of a core wound with a coil wound around a wire rod, a core part mainly containing magnetic powder and a resin, and a conductive paste on the surface of the core part. It has an external electrode. A core part is formed in the shape which has an upper surface, a bottom face, and a pair of opposing end faces of width narrower than the center part of a core part. At this time, the core portion is formed so that each end of the coil is exposed on the surface of the opposite end surface. A conductive paste is applied to a part of the end face and the bottom face by a printing method to be 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.

Description

SURFACE MOUNT INDUCTOR AND METHOD OF MANUFACTURING THE SAME

The present invention relates to a small surface mount inductor and a method of manufacturing the same.

BACKGROUND OF THE INVENTION A surface mount inductor containing a coil wound around a wire in a core is widely used. Background Art With the recent miniaturization and ultra-thinning of electronic devices such as mobile phones, electronic components such as surface mount inductors are also required to be miniaturized and reduced in size. The applicant has proposed a coil wound in a spiral shape so that both ends of the flat conductor are drawn out to the outer circumference, a small surface mount inductor using a preformed tablet, and a method of manufacturing the same (Japanese Patent Laid-Open No. 2010-245473).

This surface mount inductor is set in a molding die in a state in which a coil wound with a flat lead wire is mounted on a tablet, and a molded article having a rectangular parallelepiped shape is obtained by compression molding at a softening point or more of the tablet. In the molded body, external electrodes are formed using a method such as dip from both sides. Therefore, in this surface mount inductor, as shown in FIG. 13, the external electrode 103 is formed over five surfaces of the molded object 102. As shown in FIG.

As electronic devices become more miniaturized and larger in current, high density mounting on circuit boards of electronic components is required. In the conventional surface mount inductor, 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 electrode is formed on the side surface. Therefore, such a surface mount inductor needs to be mounted at a certain distance so that external electrodes of neighboring electronic components do not come into contact with each other, which is disadvantageous for high density mounting. Moreover, in such a surface mount inductor, there was a possibility that the external electrode formed on the upper surface was shorted in contact with the metal shield plate.

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

In order to solve the above problems, the surface-mount inductor of the present invention includes a coil wound around a wire rod, a core portion enclosing a coil mainly made of magnetic powder and a resin therein, and L formed using a conductive paste on the surface of the core portion. It has a magnetic external electrode. A core part is formed in the shape which has an upper surface, a bottom face, and a pair of opposing end faces of width narrower than the center part of a core part. At this time, the core portion is formed so that each end of the coil is exposed on the surface of the opposite end surface. An electrically conductive paste is applied to a part of the end face and the bottom face of the core portion and electrically connected to the end portion of the coil to form an external electrode. The external electrode is formed to have a narrower width than the central portion of the core portion and does not reach the upper surface of the core portion.

(Effects of the Invention)

Since the surface mount inductor of the present invention forms the external electrode to be narrower than the width of the core portion and does not reach the top surface, high density mounting on the circuit board can be realized.

Since the surface mount inductor of the present invention can increase the area of the core and the coil by the thickness of the electrode other than the mounting surface compared with the conventional surface mount inductor, the surface mount inductor is advantageous in terms of the L value, the DC resistance, and the DC superposition characteristic. Alternatively, the size of the electrode can be reduced or reduced.

In addition, since the surface area inductor of the present invention has a smaller electrode area than conventional surface mount inductors, eddy currents due to leakage magnetic flux are less likely to occur, which is advantageous in terms of circuit efficiency.

1 is a perspective view of a coil used in an embodiment of the present invention.
Fig. 2 is a perspective view of the core portion of the first embodiment of the present invention.
3 is a top view of the core portion of the first embodiment of the present invention.
4 is a perspective view of the surface mount inductor of the first embodiment of the present invention.
5 is a view for explaining an external electrode of the surface mount inductor of the first embodiment of the present invention.
6 is a perspective view of another embodiment of the surface mount inductor of the present invention.
7 is a perspective view of another embodiment of the surface mount inductor of the present invention.
8 is a perspective view of a core portion of a second embodiment of the present invention.
Fig. 9 is a side view of the core portion of the second embodiment of the present invention.
10 is a perspective view of the surface mount inductor of the second embodiment of the present invention.
11 is a perspective view of another embodiment of the surface mount inductor of the present invention.
12 is a perspective view of another embodiment of the surface mount inductor of the present invention.
13 is a perspective view of a conventional surface mount inductor.

EMBODIMENT OF THE INVENTION Below, the Example of the surface mount inductor of this invention and its manufacturing method is demonstrated, referring drawings.

EXAMPLE

(First embodiment)

1 to 5, a first embodiment of the surface mount inductor of the present invention will be described. The perspective view of the coil used by the following example in FIG. 1 is shown. 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 of the first embodiment of the present invention. 5 is a view for explaining an external electrode of the surface mount inductor of the first embodiment of the present invention.

First, as shown in FIG. 1, the coil 1 was obtained by winding the flat conducting wire which has a self-adhesive film in two outer periphery windings using the elliptical winding of cross-sectional shape. The coil 1 was produced in the shape which has the winding part 1a which wound the wire rod, and the both ends 1b which led out so that the winding part 1a could be opposed.

Next, as shown in FIG. 2, the core part 2 was formed using the compression molding method so that the coil 1 might be enclosed in the sealing material obtained by mixing iron type magnetic metal powder and an epoxy resin. At this time, the end part 1b of the coil 1 is formed so that it may expose on the surface of the opposing both end surface of the core part 2. As shown in FIG. 3, in the present embodiment, the core portion 2 is formed in an octagonal shape such that the width W2 of the end surface of the core portion 2 is smaller than the width W1 of the central portion of the core portion 2. .

Subsequently, sandblasting is performed to remove burrs and the coating on the surfaces of both ends 1b to be exposed, and then a conductive paste is transferred and cured to a part of the end face and the bottom face of the core portion 2. As a result, the conductive paste and the internal coil 1 become conductive. Finally, a plating process is performed to form a plating layer on the surface of the conductor paste, and an 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. In addition, the conductive paste is transferred so as not to reach the upper surface of the core portion 2 by a printing method, so that the external electrode 3 is formed so as not to reach the upper surface of the core portion 2. In addition, what is necessary is just to form the electrode formed by plating process by selecting one or more from Ni, Sn, Cu, Au, Pd, etc. suitably.

Here, another embodiment similar to the first embodiment is shown. 6 and 7 show perspective views of another embodiment of the surface mount inductor of the present invention. The core portion 2 has the same effect as the octagonal core portion of the first embodiment even if it is formed in a cross shape as shown in FIG. 6 or a rectangle with rounded corners as shown in FIG.

(Second embodiment)

A second embodiment of the surface mount inductor of the present invention will be described with reference to FIGS. 8 to 10. 8 and 9 show a core part of a second embodiment of the present invention, FIG. 8 is a perspective view and FIG. 9 is a side view. 10 is a perspective view from an upper surface side of the surface mount inductor of the second embodiment of the present invention. In the second embodiment, the coil and the sealing material used in the first embodiment are used. Description of portions overlapping with the first embodiment will be omitted.

First, the core part 12 was formed using the compression molding method so that a coil might be enclosed in the inside with a sealing material. At this time, the end portion 1b of the coil is formed to be exposed on the surfaces of opposing end surfaces of the core portion 12. In this embodiment, as in the first embodiment, the core portion 12 is formed in an octagonal shape, and as shown in FIG. 9, the height H2 of the end surface of the core portion 12 is greater than the height H1 of the center portion. The upper surface was formed in taper shape so that it might become low.

Subsequently, sandblasting is performed to remove the burr and to remove the coating on the surfaces of the both ends 1b exposed, and then a conductive paste is applied to the end face and a part of the bottom face of the core portion 12 by roller printing to cure. As a result, the conductive paste and the internal coils become conductive. Finally, a plating process is performed to form a plating layer on the surface of the conductor 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 printing, so that the external electrode does not reach the upper surface of the core portion without the need for height control as in the first embodiment. It can be formed without.

Here, another embodiment similar to the second embodiment is shown. 11 and 12 show perspective views of another embodiment of the surface mount inductor of the present invention. As shown in FIG. 11 and FIG. 12, even if the core part 12 is formed in the shape which has a level | step difference on the upper surface of the core part 12, the same effect as the core part which has a tapered upper surface of 2nd Example is acquired.

In the above embodiment, an iron-based magnetic metal powder was used as the magnetic powder, and an epoxy resin was used as the binder. By using ferrous metal magnetic powder, it is possible to fabricate a surface mount inductor having excellent DC superposition characteristics. However, the present invention is not limited to this. For example, ferrite-based magnetic powder or the like, or magnetic powder subjected to surface modification such as insulating film formation or surface oxidation may be used. Moreover, you may add inorganic substances, such as glass powder. And as a binder, you may use thermosetting resins, such as a polyimide resin and a phenol resin, thermoplastic resins, such as a polyethylene resin and a polyamide resin, an inorganic binder, etc.

In the above embodiment, an elliptical circumferential wound coil was produced using a flat conductor, but not limited to this, a coil having a shape of a circle, a fan, a semicircle, a trapezoid or a polygon, or a combination thereof may be used. Moreover, a round wire etc. which are not a flat conducting wire may be employ | adopted, an alignment winding, edgewise winding, etc. may be sufficient as a non-peripheral winding.

In the said embodiment, although the core was produced using the compression molding method which is one of the plastic shaping | molding methods, it is not limited to this, For example, you may produce a core using shaping | molding methods, such as a press molding method.

In the said embodiment, although sandblasting was used as a method of removing a burr and peeling off the film of the end surface of a coil, it is not limited to this, The film peeling methods, such as burr removal by a barrel grinding etc. and mechanical peeling, can also be used. In addition, you may peel a film of an edge part before forming a core part.

1: coil 1a: winding part
1b: end 2, 12: core
3, 13: external electrode

Claims (13)

With the coil wound the wire rod,
A core part including magnetic powder and resin, and encapsulating the coil therein;
Has 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 an upper surface, a bottom surface, and a pair of opposite end surfaces having a narrower width than a central portion of the core portion.
Each end of the coil is exposed on the surface of the opposite end face,
Applying an electrically conductive paste to the end surface and a part of the bottom surface to electrically connect with the end of the coil, and to form an external electrode covering the end surface and a part of the bottom surface;
In this case, the external electrode is a surface-mount inductor, characterized in that the width is narrower than the central portion of the core portion and is formed so as not to reach the upper surface of the core portion. The method of claim 1,
The surface-mount inductor of the core portion is formed in a shape in which the four corners are cut out so that the width of the end surface is narrower than the center portion. The method of claim 2,
The surface-mount inductor of the core portion is any one of an octagon, a cross-shaped, and a rounded rectangle. The method of claim 1,
And the upper surface of the core portion is formed in a convex shape, and the height of the end surface is lower than the height of the center portion of the core portion. The method of claim 2,
And the upper surface of the core portion is formed in a convex shape, and the height of the end surface is lower than the height of the center portion of the core portion. The method of claim 3, wherein
And the upper surface of the core portion is formed in a convex shape, and the height of the end surface is lower than the height of the center portion of the core portion. The method of claim 4, wherein
And the upper surface of the core portion has a tapered shape or a stepped shape. The method of claim 5,
And the upper surface of the core portion has a tapered shape or a stepped shape. The method of claim 6,
And the upper surface of the core portion has a tapered shape or a stepped shape. Winding the wire rod to form a coil,
Preparing a sealing material containing a magnetic powder and a resin;
Forming a core part using the sealant to seal the coil therein;
Applying an electrically conductive paste to a portion of the end face and the bottom face of the core part to electrically connect the end portion of the coil, and to form an L-shaped external electrode covering the end face and a part of the bottom face,
In the step of forming the core portion, the core portion is formed in a shape having an upper surface, a bottom surface, and a pair of opposing end surfaces having a narrower width than a central portion of the core portion, and each end of the coil is formed on a surface of the opposing end surface. Sealed so that it is exposed,
And in the step of forming the external electrode, the external electrode is formed to have a width narrower than the center portion of the core portion and does not reach the upper surface of the core portion. The method of claim 10,
In the step of forming the core portion, the manufacturing method of the surface mount inductor, characterized in that the four corners are formed in a shape that is cut so that the width of the end surface is narrower than the center portion. The method of claim 10,
In the step of forming the core portion, the upper surface is formed in a convex shape, the manufacturing method of the surface-mount inductor, characterized in that the height of the end surface is lower than the height of the center portion of the core portion. The method of claim 11,
In the step of forming the core portion, the upper surface is formed in a convex shape, the manufacturing method of the surface-mount inductor, characterized in that the height of the end surface is lower than the height of the center portion of the core portion.

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