KR101981515B1 - Method of manufacturing surface mount inductor - Google Patents

Abstract

[PROBLEMS] To provide a method of manufacturing a small-sized surface-mounted inductor.
[MEANS FOR SOLVING PROBLEMS] In a method of manufacturing a surface-mounted inductor of the present invention, a tablet is formed by preforming a sealing material into a shape having a columnar convex portion in a peripheral edge portion of a flat plate. The coil is formed by winding the flat wire. The coils are mounted on the tablet, and both ends of the coils are arranged on the molding die along the outer side surfaces of the columnar convex portions of the tablet. The core and the coil are integrally formed by using a resin molding method or a powder compacting method in a state where both ends of the coil are sandwiched between the outer side face of the columnar convex part of the tablet and the inner wall face of the molding die. The surface of the core portion other than the surface on which both ends of the coil are exposed is polished or cut to resize the core portion. And an external electrode is provided on the surface of the core portion, the external electrode being connected to a portion where at least a part of both ends of the coil are exposed.

Description

METHOD OF MANUFACTURING SURFACE MOUNT INDUCTOR [0002]

The present invention relates to a method of manufacturing a small-sized surface-mounted inductor.

Surface-mounted inductors in which a coil wound with a wire is enclosed in a core are widely used. 2. Description of the Related Art Recently, electronic devices such as surface mounted inductors have been required to be miniaturized and reduced in height due to miniaturization and thinning of electronic devices such as cellular phones. Therefore, the applicant proposed a small surface mounted inductor using a coil and a preformed tablet wound in a spiral shape so that both ends of the end portion of the square conductor are drawn out to the outer periphery, and a manufacturing method thereof.

In this conventional method of manufacturing a surface-mounted inductor, a sealing material containing a resin and a filler is first preliminarily formed into a shape having a columnar convex portion in a peripheral edge portion of a flat plate to prepare a tablet. Next, a conductor having a flat cross section is wound to form a coil, and the coil is mounted on the tablet. At this time, both ends of the coil are disposed along the columnar convex part of the tablet, and the coil and the tablet are arranged in the molding die so that both ends of the coil are sandwiched between the outer side face of the columnar convex part of the tablet and the inner wall face of the molding die, The preformed sealing material is loaded in the mold. Then, the coil and the sealing material are integrated by using a resin molding method or a powder compacting method in a state where both ends of the coil are sandwiched between the outer side face of the columnar convex part of the tablet and the inner wall face of the molding die. Finally, an external electrode connected to a portion where at least a part of both ends of the coil are exposed is formed on the surface or the outer periphery of the molded body to obtain a surface-mounted inductor.

Japanese Patent Application Laid-Open No. 2010-245473

In a conventional method of manufacturing a surface-mounted inductor, a sealing material containing a resin and a filler is preliminarily molded in advance into a tablet having a columnar convex portion in the periphery of a planar shape. Particularly, considering the position of the coil, it is preferable to form the tablet 102 in a shape having a columnar convex portion 102a surrounding the coil 101 as shown in Fig. However, in order to obtain a surface mounted inductor having a size of 2 mm or less, the size of the tablet is reduced and the columnar convex portion must also be thinned. In the tablet made of the sealing material (in particular, the content of the filler is 60 vol% or more) by including the resin and the filler in the case where the size of the tablet is made small, it is possible to secure sufficient mechanical strength by preforming into a complicated shape having the columnar convex portion It becomes difficult. When the mechanical strength of the tablet is lowered, a part of the tablet is likely to be defective or damaged when the tablet is carried or loaded with a molding die. If a part of the tablet is defected or damaged, there is a possibility that the position of the internal coil is shifted or a defective shape is formed, and the inductor characteristic or imbalance may occur. Therefore, the columnar convex portion of the tablet has to be secured to a certain thickness, and there is a limit to the miniaturization and the lowering in the manufacturing method of the conventional surface-mounted inductor.

However, when a core portion containing a coil is formed by using a magnetic material-containing resin obtained by mixing magnetic powder and resin as a sealing material, the structure becomes a closed-loop structure. The magnetic flux passes through the core portion so as to surround the peripheral edge of the coil from the core portion to the outer peripheral portion of the coil. Considering the magnetic saturation of the core portion containing the coil, it is sufficient that the outer peripheral portion of the coil in the core portion is secured to the same extent as the area of the core portion of the coil. 18 shows the top surface transmittance of the core portion formed by the conventional method of manufacturing a surface-mounted inductor. In the core portion 103, the area S2 of the outer peripheral portion is formed larger than the area S1 of the core portion. This is because, in the case of the conventional method of manufacturing a surface-mounted inductor, it is necessary to secure a certain thickness to the columnar convex portion of the tablet and thereby to make the area S2 of the outer peripheral portion of the core portion 103 larger than necessary . The smaller the size of the core itself, the smaller the size of the coil itself, but the thickness of the columnar convex portion of the tablet can not be made thinner than a certain level, and this tendency becomes remarkable.

Therefore, it is an object of the present invention to provide a method of manufacturing a smaller surface-mounted inductor.

In order to solve the above problems, a method of manufacturing a surface-mounted inductor according to the present invention uses a molding die to seal a coil with a sealing material containing a resin and a filler. The tablet is formed by preliminarily molding the sealing material into a shape having a columnar convex portion in the peripheral edge portion of the flat plate shape. A wire having a flat cross section forms a wound coil. The coils are mounted on the tablet, and both ends of the coils are disposed along the outer side surfaces of the columnar convex portions of the tablet. Then, the coil and the sealing material are integrated by the resin molding method or the powder compacting method in a state in which both ends of the coil are sandwiched between the outer side surface of the columnar convex portion of the tablet and the inner wall surface of the molding die. At least one surface other than the surface on which both ends of the coil of the core portion are exposed is polished or cut to resize the core portion. And an external electrode connected to a portion of the core portion on which at least a part of both ends of the coil are exposed is provided on a surface or an outer periphery of the core portion.

[Effects of the Invention]

The method of manufacturing a surface-mounted inductor of the present invention realizes a further miniaturization and a reduction in surface-mounted inductors. In addition, if a surface-mount inductor of the same size as the conventional one is formed, the built-in coil can be made larger or the coarse wire can be selected. As a result, characteristics of the surface-mounted inductor such as reduction in direct current resistance and improvement in inductance value can be improved.

1 is a perspective view of a coil used in the first embodiment of the present invention.
2 is a perspective view showing the arrangement of a coil, a tablet, and a plate-like tablet according to the first embodiment of the present invention.
3 is a top view showing the arrangement of a coil and a tablet in a forming die of the first embodiment of the present invention.
Fig. 4 is a cross-sectional view for explaining a process of disposing a coil and a tablet in a molding die in the manufacturing method of the first embodiment of the present invention, and corresponds to the ABCD combination section in Fig.
5 is a cross-sectional view for explaining a forming step of the core portion in the manufacturing method of the first embodiment of the present invention, and corresponds to the ABCD combination cross section in Fig.
6 is a perspective view of a core portion before resizing of the first embodiment of the present invention.
7 is a top surface transmission of the core portion after the resizing of the first embodiment of the present invention.
8 is a perspective view of a core portion after resizing of the first embodiment of the present invention.
9 is a perspective view of a surface-mounted inductor according to the first embodiment of the present invention.
10 is a perspective view of a coil used in a second embodiment of the present invention.
11 is a perspective view showing the arrangement of a coil and a tablet in the second embodiment of the present invention.
12 is a top view showing the arrangement of a coil and a tablet in a molding die of a second embodiment of the present invention.
Fig. 13 is a cross-sectional view for explaining a part of the manufacturing process of the second embodiment of the present invention, and shows the steps of the ABCD combination cross section of Fig. 12.
14 is a perspective view of a core portion before resizing of the second embodiment of the present invention.
15 is a perspective view of a core portion after resizing of the second embodiment of the present invention.
16 is a perspective view of a surface-mounted inductor according to a second embodiment of the present invention.
17 is a perspective view illustrating a conventional tablet.
18 is a top view transmission of a conventional core portion.

Hereinafter, a method of manufacturing the surface-mounted inductor of the present invention will be described with reference to the drawings.

(Embodiment 1)

A first embodiment of a method of manufacturing a surface-mounted inductor of the present invention will be described with reference to Figs. 1 to 9. Fig. First, the coil used in the first embodiment will be described. 1 is a perspective view of a coil used in the first embodiment. As shown in Fig. 1, the coil 1 is obtained by forming the winding portion 1a by winding the flat wire in two outer windings so that the both ends 1b are the outermost periphery. And the end portion 1b is drawn out so as to face each other with the winding portion 1a interposed therebetween.

Next, the sealing material used in the first embodiment will be described. In this embodiment, a mixture of an iron-based metal magnetic powder and an epoxy resin is used as a sealing material. A tablet is prepared using this sealing material. Fig. 2 shows the arrangement relationship between the coil, the tablet and the plate-like tablet of the first embodiment. The tablet 2 and the plate-shaped tablet 3 are prepared by press molding. In order to increase the strength of the tablet 2 in this embodiment, the heat treatment is further carried out to set the sealing material to a semi-cured state. As shown in Fig. 2, the tablet 2 is formed into a shape having two columnar convex portions 2a at the periphery of the plane portion so as to surround the coil 1. [ Both ends 1b of the coil 1 are arranged along the outer side surface of the columnar convex portion 2a.

Next, the step of arranging the coil and the tablet of the manufacturing method of the first embodiment in the forming die will be described. Figs. 3 and 4 show arrangements of coils and tablets in a molding die. Fig. 4 is a cross-sectional view corresponding to the A-B-C-D combination cross section in Fig. As shown in Figs. 3 and 4, in the first embodiment, the die 4 made of the split mold die 4a and the split mold die 4b, and the molding die having the lower mold 5 and the punch 6 . The tablet 2 in which the coil 1 is disposed is loaded in the forming die and the plate-like tablet 3 is loaded thereon. When the coil 1 and the tablet 2 are arranged as described above, the coil 1 is arranged at a suitable height in the molding die depending on the thickness of the flat portion of the tablet 2. [ Both end portions 1b of the coil 1 are held by the inner wall surfaces of the columnar convex portion 2a of the tablet 2 and the die 4b and both end portions 1b of the coil 1 are positioned at appropriate positions . Then, the punch 6 is set to preheat the molding die. In this embodiment, the forming die is preheated to a softening temperature of the sealing material or higher, so that the tablet 2 and the plate-shaped tablet 3 are softened.

Next, a step of molding the core portion of the manufacturing method of the first embodiment will be described. Fig. 5 is a cross-sectional view for explaining a molding step of the core portion in the manufacturing method of the first embodiment. 5 corresponds to the A-B-C-D combination cross section in Fig. As shown in Fig. 5, the tablet 2 and the tabular tablet 3 are integrated by pressing using the punch 6 to cure the sealing material. At this time, the tablet 2 and the plate-shaped tablet 3 are softened and easily seal the coil 1. Both end portions 1b of the coil 1 are sealed in a state in which at least a part thereof is buried in the sealing material without positional deviation. Then, the core portion 7 obtained by hardening the sealing material is drawn out from the molding die. The plane of the end portion 1b of the coil 1 is exposed on the surface of the core portion 7 as shown in Fig.

Next, the resizing process of the core portion will be described. 7 and 8 show the core portion after resizing. As shown in Figs. 7 and 8, in the first embodiment, the two side surfaces of the core portion 7 where the end portion 1b of the coil is not exposed are polished to resize the core portion 7. 7, the core portion 7 is resized so that the area S2 of the outer peripheral portion of the coil 1 in the core portion 7 is in the range up to the area S1 of the core portion of the coil 1, , And it is more preferable to resize such that S1 and S2 are equal to each other.

Finally, conductive resin is applied to the surface of the core portion 7 so as to be connected to the end portion 1b exposed on the surface of the core portion 7. In this embodiment, the two side surfaces and the bottom surface on which the end portion 1b is exposed are coated in an L-shape so as to face each other using a printing method. Subsequently, plating is performed to form the external electrode 8 to obtain the surface-mounted inductor shown in Fig. The electrode formed by the plating process may be formed by appropriately selecting one electrode or a plurality of electrodes from Ni, Sn, Cu, Au, Pd or the like.

(Second Embodiment)

A second embodiment of a method of manufacturing a surface-mounted inductor of the present invention will be described with reference to FIGS. 10 to 16. FIG. In the second embodiment, a material having the same composition as that of the sealing material used in the first embodiment is used. Further, the description of the parts common to those of the first embodiment will be omitted.

First, the coil used in the second embodiment will be described. 10 shows a perspective view of the coil used in the second embodiment. As shown in Fig. 10, the coil 1 is obtained by winding a flat wire through two outer windings. So that the end portion 1b is drawn out to the same side of the coil 1 side.

Next, the tablet used in the second embodiment will be described. 11 is a perspective view for explaining the arrangement of the coil and tablet of the second embodiment. The tablet 12 is formed using the sealing material by press molding. In this embodiment, the tablet 12 is used in an uncured state. As shown in Fig. 11, the tablet 12 and the coil 11 are molded into a shape having a columnar convex portion 12a at the periphery of the plane portion so as to surround the tablet 12 and the coil 11. [ Both end portions 11b of the coil 11 are disposed so as to extend along the outer side surfaces of the columnar convex portions 12a so that the same side of the tablet 12 is drawn out.

Next, the process of arranging the coil and the tablet in the molding die and the process of molding the core portion in the manufacturing method of the second embodiment will be described. Fig. 12 shows the arrangement of coils and tablets in a molding die. 13 is a cross-sectional view illustrating a part of the manufacturing process of the second embodiment. 13 corresponds to the A-B-C-D combination cross section in Fig. 12 and 13 (a), in the second embodiment, the die 14 composed of the split mold die 14a and the split die 1 (die) 14b and the die 14 composed of the lower die 15 and the punch 16 ) Is used. The tablet 12 in which the coil 11 is disposed is placed in the molding die.

Subsequently, as shown in Fig. 13 (b), the powdery sealing material 13 is put on the coil 11 and the tablet 12 in a predetermined amount, and the punch 16 is set. In this embodiment, a seal material having the same composition as that used when the tablet 12 was prepared as a powder-form seal material was used. The powdery sealing material may be formed in an uncured or semi-cured state like a tablet.

Subsequently, as shown in Fig. 13 (c), the tablet 12 and the powdery sealing material 13 are integrally formed by a punch molding method using the punch 16 to form the core portion 17. At this time, the tablet 12 is reshaped to seal the coil 11 together with the powdery sealing material 13. The end portion 11b of the coil 11 is sealed in a state in which at least a part of the end portion 11b is buried in the core portion 17 without positional deviation. After the sealing material is cured, it is taken out from the molding die to obtain the core portion 17 shown in Fig. 14, the plane of the end portion 11b of the coil 11 is exposed on one side surface of the core portion 17, as shown in Fig.

Next, the resizing process of the core portion will be described. Fig. 15 is a perspective view of the core after resizing. In the second embodiment, the three side surfaces and the top and bottom surfaces of the core portion 17 where the end portion 11b of the coil is not exposed are cut off, and the core portion 17 is resized. In this embodiment, the core portion is further downsized with a smaller size. At this time, as for the side to be cut, the core portion may be resized so that the area of the outer peripheral portion of the coil is within the range of the area of the core portion of the coil, as in the first embodiment. For the upper and lower surfaces, the minimum cross-sectional area through which the magnetic flux passes may be ensured. An area obtained by multiplying the circumferential length of the core portion of the coil by the height of the top surface or bottom surface from the coil is equal to or larger than the area of the core portion of the coil. In the case of this embodiment, the core portion was cut out so that the product of the circumferential length of the core portion of the ellipse and the height from the coil to the upper surface or the bottom surface is equal to the area of the core portion of the coil.

Finally, a conductive resin is applied to the surface of the core portion 17 so as to be connected to the end portion 11b. Subsequently, plating is performed to form the external electrode 18 to obtain the surface-mounted inductor shown in Fig.

In the above embodiment, iron-based metal magnetic powder and epoxy resin were used as the sealing material. By using the iron-based metal magnetic powder, it is possible to manufacture a surface-mounted inductor excellent in direct current superposition characteristics. However, the present invention is not limited to this, and for example, ferrite magnetic powder, glass powder, or the like may be used as a filling material. As the resin, a thermosetting resin such as a polyamide resin or a phenol resin, or a thermoplastic resin such as a polyethylene resin or a polyamide resin may be used. The core portion may be formed by combining different kinds of cores such as a ferrite core. However, when the surface of the core portion is formed of the same material at the time of polishing or the like, the stress applied to the core portion becomes uniform.

In the above embodiment, an air-core coil wound with two outer windings is used as the coil. However, the present invention is not limited to this, and for example, a winding method such as edge-wise winding or a coil having a circular, rectangular or trapezoidal shape may be used.

Although the plate-shaped tablet is used in the first embodiment, it is not limited to the plate shape but may be preformed into a shape such as a T shape or an E shape. Further, it may be a semi-cured state instead of an uncured state. The molding method may be suitably selected in accordance with the application such as a pressure molding method or a method in which the molded article is taken out from the sheet molding.

1, 11: coil (1a, 11a: winding section, 1b, 11b: end)
2, 12: Tablet
3: Tabular tablet
4, 14: dies 4a, 4b, 14a, 14b: split mold die)
5, 15: Lower mold
6, 16: punch
7, 17: core part
8, 18: external electrode
13: Powder-shaped sealing material

Claims (3)

A method of manufacturing a surface-mounted inductor in which an air-core coil wound with a conductive wire having a rectangular cross-section is sealed with a sealing material containing a resin and magnetic powder using a molding die, comprising:
Molding the tablet by preforming the sealing material into a shape having a columnar convex portion formed so as to surround the coil in a peripheral edge portion of a flat plate shape;
Winding a lead wire having a flat cross section such that the lead-out end is located at the outermost periphery, thereby forming the coil;
Placing the coil on the tablet and disposing the lead-out end of the coil along the outer side surface of the columnar convex portion of the tablet to the forming die;
The coil and the sealing material are integrated by using a resin molding method or a powder compacting method in a state where the lead-out end of the coil is sandwiched between the outer side face of the columnar convex portion of the tablet and the inner wall face of the molding die, A step of forming a core portion in which a surface of a lead-out end of the core portion is exposed,
A step of polishing or cutting the two side surfaces orthogonal to the side surface of the core portion on which the lead-out end of the coil is exposed to resize the core portion;
And a step of providing an external electrode on the surface or the periphery of the core portion, the external electrode being connected to a surface of the core portion, the portion being exposed at least a part of the lead-
Wherein the core portion has an outer peripheral portion area of the coil and an inner core area of the coil are the same. A method of manufacturing a surface-mounted inductor in which an air-core coil wound with a conductive wire having a rectangular cross-section is sealed with a sealing material containing a resin and magnetic powder using a molding die, comprising:
Molding the tablet by preforming the sealing material into a shape having a columnar convex portion formed so as to surround the coil in a peripheral edge portion of a flat plate shape;
Winding a lead wire having a flat cross section such that the lead-out end is located at the outermost periphery, thereby forming the coil;
Placing the coil on the tablet and disposing the lead-out end of the coil along the outer side surface of the columnar convex portion of the tablet to the forming die;
The coil and the sealing material are integrated by using a resin molding method or a powder compacting method in a state in which the lead end of the coil is sandwiched between the outer side face of the columnar convex part of the tablet and the inner wall face of the molding die, Forming a core portion exposed on the same side of the surface,
A step of polishing or cutting the three side surfaces of the core portion where the lead-out end of the coil is not exposed, thereby resizing the core portion;
And a step of providing an external electrode on the surface or the periphery of the core portion, the external electrode being connected to a surface of the core portion, the portion being exposed at least a part of the lead-
Wherein the core portion has an outer peripheral portion area of the coil and an inner core area of the coil are the same. 3. The method according to claim 1 or 2,
Wherein a plate-like tablet or powder-like sealing material is loaded in the molding die on the tablet on which the coil is mounted, and the coil and the sealing material are integrated by using a resin molding method or a powder compacting method.

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