JP4376168B2 - Inductor and manufacturing method thereof - Google Patents

Description

  The present invention relates to an inductor used for a power supply circuit of a portable terminal, an electronic device, and the like and a manufacturing method thereof.

  In recent years, with the miniaturization and high output of devices, demands for low resistance and miniaturization are increasing for inductors used in power supply circuits. In response to these requirements, inductors have been developed in which windings are placed in magnetic powder and compacted in a molding die. Since this inductor is an inductor having a low resistance due to a high line occupancy ratio and no useless space, market needs are very high, high productivity is required, and many inventions for improving productivity have been proposed.

FIG. 6 is a cross-sectional view when the winding 41 is inserted into a molding die in a conventional inductor. The green compact 1c previously formed is placed on the lower punch 71 of the molding die, and then the winding 41 is disposed between the lower die 51 of the molding die and the upper die 61 of the molding die, and the magnetic powder is introduced. Then, the whole is molded to obtain an inductor.

  For example, Patent Document 1 proposes a manufacturing method in which two green compacts are formed in advance, placed together with a winding in a molding die, and the green compact is crushed and reconsolidated. However, with this method, the winding terminal can be accurately gripped and positioned in the mold. However, in the case of winding with a large amount of spring back such as a rectangular wire, the terminal shape varies greatly, and the inside of the mold Winding position will fluctuate greatly.

  In Patent Document 2, both terminals of the winding are once exposed to the outside of the green compact, and the terminals are separately joined thereto. However, this method increases the number of steps involved in joining and makes the structure complicated. This will be a factor that hinders downsizing of the inductor.

  In Patent Document 3, a manufacturing method is proposed in which a winding is connected and fixed to a lead frame, and positioning is performed using a lead frame in a molding die. However, as in Patent Document 2, a connection process to a lead frame is performed. It will increase. Furthermore, there is a proposal that positioning can be performed accurately by making the shape of the green compact into a spiral shape, but considering the possibility of contact with the green compact when inserting the winding, a simple spiral shape has some degree of A gap must be made. In that case, it is necessary to secure a gap with a degree of variation in winding position due to the above-described springback, which is not an effective measure for positioning the winding.

JP 2002-252120 A JP 2002-324714 A JP 2002-319517 A

  Inductors that are manufactured by compacting and forming a winding inside the green compact have a problem in the positioning accuracy of the winding. For this reason, the product dimensions have to be set larger than the coil outer shape, which is one factor that hinders downsizing of the inductor. Accordingly, an object of the present invention is to provide an inductor and a method of manufacturing the same that ensure the winding positioning accuracy.

In the present invention, the green compact, which is the first part, is placed in the mold in advance, the winding is positioned inside the mold, and the green compact is fitted to the inner diameter of the coil. And a frustoconical shape at the tip of the projection .

That is, the present invention relates to an inductor composed of a magnetic core formed by combining a first portion and a second portion, a winding included in the magnetic core, and an external terminal. The external terminal is formed such that an end portion of the winding is drawn out of the magnetic core, and the first portion has a cylindrical portion and a truncated cone shape at the center of a flat plate. The green compact is a green compact in which protrusions in the shape of the unit are arranged, and is preformed before the integral molding of the inductor, and the second part is the green compact as the first part. And an inductor having a shape formed at the stage of press molding after assembling the wire and the winding.

Further, the present invention, the magnetic powder in the green compact is molded by pressing in advance, after fitting the windings, the magnetic powder in the mold was charged, it is manufactured by press-forming the whole in the method for manufacturing an inductor, the powder compact has a protruding portion for the inner diameter mating of the winding, and the shape of the protrusions, and the cylindrical section, the coalesced shape of a truncated cone shape of the tip and, after the powder compact was placed in a mold, the projection portion of the green compact, is a manufacturing method of the inductor to be fitted inside the winding.

  With the above configuration, when the coil is inserted after the green compact is placed in the mold, the truncated cone-shaped portion at the tip of the projection serves as a guide, and the coil can be guided to a predetermined position. The gap between the coil inner diameters can be set small. For this reason, it is possible to accurately position the coil with respect to the molding die, it is possible to reduce molding defects due to the displacement of the coil, and it is very effective for downsizing the inductor.

  Hereinafter, embodiments of the inductor of the present invention will be described with reference to the drawings.

  FIG. 1 is an explanatory diagram of an inductor according to the present invention. FIG. 1A is a top view, and FIG. 1B is a cross-sectional view taken along line AA in FIG. The inductor 10 includes a green compact 1a, a winding 40, and a magnetic core portion excluding the green compact 1a. Here, the boundary between the green compact 1a and the magnetic core portion excluding the green compact 1a remains even after the inductor is completed.

  FIG. 2 is a perspective view of a green compact 1a which is the first part of the inductor according to the present invention. FIG. 3 is a perspective view of another example of the green compact 1b of the inductor of the present invention, and FIG. 4 shows the green compact 1b shown in FIG. It is sectional drawing when inserting a coil | winding. FIG. 5 is a cross-sectional view when a winding is inserted into the green compact shown in FIG. 3 with a molding die in the inductor manufacturing method of the present invention.

  As shown in FIGS. 2 and 3, the green compact of the inductor according to the present invention has a truncated cone-shaped protrusion, so that the winding is inserted into the mold as shown in FIGS. At this time, since the projection functions as a guide for fitting with the inner diameter of the winding, it is possible to accurately position the winding. At that time, the terminal position varies due to the spring back of the winding, so the center position of the winding also tends to change, but because of the frustoconical shape part of the green compact, it exceeds the gap between the inner diameter of the winding and the outer shape of the protrusion. It does not fluctuate.

  Furthermore, since the projection has a guide having a conical shape, it can be easily inserted and the gap between the inner diameter of the winding and the outer shape of the projection can be made smaller than a green compact having a rectangular cross section. A flat wire is mainly used for the winding, and it is usually manufactured by edgewise winding. However, since the inner diameter of the winding is regulated by the outer shape of the core used at the time of winding, there is a variation compared to the winding outer shape. There are very few. For this reason, since it is only necessary to consider a gap between the green outer diameters of the protrusions of the green compact, variations in the coil position in the present invention are reduced compared to the case where the outer diameter of the winding is used for positioning. be able to.

  After inserting the winding, the inductor is formed by supplying magnetic powder or green compact above the winding and compacting it. In this case, it is obvious that the present invention is effective regardless of whether the magnetic powder is supplied or the green compact is supplied. In the drawing, the tip of the protrusion has a planar shape, but it may be a tip shape, and the same effect can be expected with a spherical shape.

  As the material for the magnetic core, FeSi-based, FeSiAl-based, or FeSiB-based dust materials are usually used, but amorphous materials can also be used.

  The inductor according to the present invention can improve the productivity of the inductor since the positioning of the winding is easy.

Explanatory drawing of the inductor of this invention. FIG. 1A is a top view, and FIG. 1B is a cross-sectional view taken along line AA in FIG. The perspective view of the compact used for the inductor of this invention. The perspective view of the green compact of the other example used for the inductor of this invention. Sectional drawing when inserting a coil | winding in the compact shown in FIG. 2 with a shaping die in the manufacturing method of the inductor of this invention. Sectional drawing when inserting a coil | winding in the compact shown in FIG. 3 with a shaping die in the manufacturing method of the inductor of this invention. Sectional drawing when inserting a coil | winding in a shaping die in the manufacturing method of the conventional inductor.

Explanation of symbols

1a, 1b, 1c Green compact 2a, 2b Protrusion 3a, 3b Frustum shaped part 4, 41 Winding 5, 51 Mold lower mold 6, 61 Mold upper mold 7, 71 Mold lower punch 8, 81 Punch on molding die 10 Inductor 40 Winding

Claims (2)

In the inductor composed of a magnetic core formed by combining the first part and the second part, a winding included in the magnetic core, and an external terminal, the external terminal is: An end portion of the winding is formed by being drawn out of the magnetic core, and the first portion is formed by combining a cylindrical portion and a truncated cone shape at the center of the flat plate . A green compact in which a protrusion is arranged, which is pre-molded before the inductor is integrally formed, and the second part is a green compact and a winding that are the first part. An inductor having a shape formed at the stage of press molding after assembling. The green compact is shaped by pressing magnetic powder in advance, after fitting the windings, the magnetic powder in the mold was put, in the manufacturing method of the inductor is manufactured by press-forming the whole, the green compact has a protrusion for inner diameter and fitting the windings in the center of the plate, and the shape of the protrusion, and a columnar portion, the coalesced shape of a truncated cone shape of the tip , after said green compact was placed in a mold, the projection portion of the green compact, the manufacturing method of the inductor, characterized in that to fit inside the winding.

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