JP2013183052A - Surface-mounting inductor manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small surface-mounting inductor manufacturing method.SOLUTION: In a surface-mounting inductor manufacturing method according to the present invention, a sealing material is preliminary molded into a shape having a columnar projection at a peripheral edge of a plane shape to form a tablet. A flat wire is wound to form a coil. The coil is located on the tablet, and both ends of the coil are arranged on a molding die along an outside face of the columnar projection of the tablet. While both ends of the coil are sandwiched between the outside face of the columnar projection of the tablet and an inner wall of the molding die, the coil and the sealing material are integrated using a resin molding method or a powder compaction method, so as to form a core section. By polishing or cutting a surface of the core section except for a surface on which both ends of the coil are exposed, the core section is resized. An external electrode connected to a portion at which at least one part of both ends of the coil is provided on the surface of the core section.

Description

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

  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. In view of this, the applicant has disclosed a small surface-mount inductor using a coil and a pre-formed tablet in which a flat conductor is wound in a spiral shape so that both ends thereof are drawn to the outer periphery in Patent Document 1 previously filed. And the manufacturing method was proposed.

  In the method for manufacturing a surface-mount inductor disclosed in Patent Document 1, a tablet is first prepared by pre-molding a sealing material including a resin and a filler into a shape having columnar protrusions on a peripheral edge of a flat plate shape. Next, a coil having a rectangular cross section is wound to create a coil, and the coil is placed on the tablet. At this time, both ends of the coil are arranged along the columnar convex portion of the tablet, and 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. The tablet is placed in a molding die, and a preforming sealing material is loaded into the molding die. Next, the coil and the sealing material are integrated using a resin molding method or a powder molding method with both ends of the coil sandwiched between the outer side surface of the columnar convex portion of the tablet and the inner wall surface of the molding die. To obtain a molded body. Finally, an external electrode connected to a portion where at least a part of both ends of the coil is exposed on the surface of the molded body is provided on the surface or outer periphery of the molded body to obtain a surface mount inductor.

JP 2010-245473 A

  As described above, in the method of Patent Document 1, a sealing material including a resin and a filler is preliminarily molded into a tablet having a shape having columnar protrusions on a flat peripheral edge. In particular, considering the position of the coil, as shown in FIG. 17, it is desirable to form the tablet 102 in a shape having a columnar convex portion 102 a surrounding the coil 101. However, when trying to obtain a surface-mount inductor having a size of 2 mm square or less, the size of the tablet is also reduced, and the columnar protrusions have to be thinned. Therefore, in a tablet made of a sealing material containing a resin and a filler (particularly, the content of the filler is 60 Vol% or more), it is sufficient to preform it in a complicated shape having a columnar protrusion. It becomes difficult to ensure mechanical strength. When the mechanical strength of the tablet is reduced, a part of the tablet is easily lost or damaged when it is transported or loaded into a molding die. If a part of the tablet is missing or damaged, the internal coil may be misaligned or molded, which may result in poor inductor characteristics or variations. Therefore, the columnar convex portion of the tablet has to secure a certain thickness, and there is a limit to the reduction in size and the reduction in height by the method of Patent Document 1.

  By the way, if the core part which encloses a coil is formed using the magnetic material containing resin obtained by mixing magnetic powder and resin as a sealing material, it will become a closed magnetic circuit structure. The magnetic flux passes through the core part so as to surround the coil from the core part of the coil to the outer peripheral part. In consideration of the magnetic saturation of the core part including such a coil, the outer peripheral part of the coil in the core part may be secured to the same extent as the area of the core part of the coil. Here, FIG. 18 shows a top transparent view of the core portion produced by the conventional manufacturing method. The core portion 103 has an outer peripheral area S2 larger than the core area S1. In the case of the conventional manufacturing method, a certain amount of thickness must be secured in the columnar convex portion of the tablet, and accordingly, the area S2 of the outer peripheral portion of the core portion 103 must be formed larger than necessary. Because. This tendency becomes more prominent as the size of the coil itself can be reduced as the core portion is made smaller, but the thickness of the columnar convex portion of the tablet cannot be reduced more than a certain value.

  Accordingly, an object of the present invention is to provide a method for manufacturing a smaller surface-mount inductor.

  In order to solve the above-described problems, a method for manufacturing a surface-mount inductor according to the present invention uses a molding die to seal a coil with a sealing material including a resin and a filler. A tablet is formed by preforming the sealing material into a shape having columnar protrusions on the peripheral edge of a flat plate shape. A coil is formed by winding a conducting wire having a flat cross section. The coil is placed on the tablet, and both ends of the coil are arranged on the molding die along the outer side surface of the columnar convex portion of the tablet. The coil and the sealing material are integrated using a resin molding method or a powder molding method with both ends of the coil being sandwiched between the outer side surface of the columnar convex portion of the tablet and the inner wall surface of the molding die. To form a core part. The core part is resized by polishing or cutting at least one surface other than the surface where both ends of the coil of the core part are exposed. An external electrode connected to a portion where at least a part of both end portions of the coil is exposed on the surface of the core portion is provided on the surface or outer periphery of the core portion.

  The method for manufacturing a surface-mount inductor according to the present invention realizes further reduction in size and height of the surface-mount inductor. Alternatively, if a surface-mount inductor having the same size as the conventional one is created, it is possible to increase the size of the built-in coil or select a thick wire rod. As a result, improvement in characteristics of the surface mount inductor such as reduction of DC resistance and improvement of inductance value is realized.

It is a perspective view of the coil used in the 1st example of the present invention. It is a perspective view which shows arrangement | positioning of the coil of 1st Example of this invention, a tablet, and a plate-shaped tablet. It is a top view which shows arrangement | positioning of the coil and tablet in the shaping die of the 1st Example of this invention. It is sectional drawing explaining the process of arrange | positioning the coil and tablet of the manufacturing method of 1st Example of this invention to a shaping | molding die, and respond | corresponds to the ABCD combined cross section of FIG. It is sectional drawing explaining the formation process of the core part of the manufacturing method of the 1st Example of this invention, and respond | corresponds to the ABCD combined cross section of FIG. It is a perspective view of the core part before resizing of the 1st Example of this invention. It is an upper surface penetration figure of the core part after resizing of the 1st example of the present invention. It is a perspective view of the core part after the resizing of 1st Example of this invention. 1 is a perspective view of a surface-mount inductor according to a first embodiment of the present invention. It is a perspective view of the coil used in the 2nd example of the present invention. It is a perspective view which shows arrangement | positioning of the coil and tablet of 2nd Example of this invention. It is a top view which shows arrangement | positioning of the coil and tablet in the shaping die of the 2nd Example of this invention. It is sectional drawing explaining a part of manufacturing process of 2nd Example of this invention, and shows the mode of each step in the ABCD combined cross section of FIG. It is a perspective view of the core part before resizing of the 2nd Example of this invention. It is a perspective view of the core part after the resizing of 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 explaining the conventional tablet. It is an upper surface penetration figure of the conventional core part.

  Below, the manufacturing method of the surface mount inductor of this invention is demonstrated, referring drawings.

(First embodiment)
A first embodiment of a method for manufacturing a surface mount inductor according to the present invention will be described with reference to FIGS. First, the coil used in the first embodiment will be described. FIG. 1 shows a perspective view of a coil used in the first embodiment. As shown in FIG. 1, a coil 1 is obtained by winding a flat wire around two stages of outer and outer windings so that both end portions 1b are at the outermost periphery to form a wound portion 1a. The end portion 1b was pulled 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, as the sealing material, a mixture of iron-based metal magnetic powder and epoxy resin is used. A tablet is produced using this sealing material. FIG. 2 shows the positional relationship among the coil, tablet, and plate tablet of the first embodiment. The tablet 2 and the plate-like tablet 3 are created by pressure molding. In this example, in order to increase the strength of the tablet 2, the heat treatment was further performed to make the sealing material semi-cured. As shown in FIG. 2, the tablet 2 is formed in a shape having two columnar convex portions 2 a on the periphery of the flat portion so as to surround the coil 1. Both end portions 1b of the coil 1 are arranged along the outer side surface of the columnar convex portion 2a.

  Next, the process of arranging the coil and tablet of the manufacturing method of the first embodiment in a molding die will be described. 3 and 4 show the arrangement of coils and tablets in the molding die. FIG. 4 is a cross-sectional view corresponding to the cross section taken along the line ABCD in FIG. As shown in FIGS. 3 and 4, in the first embodiment, a molding die having a die 4 composed of a split die 4a and a split die 4b, a lower die 5 and a punch 6 is used. The tablet 2 in which the coil 1 is arranged in this molding die and the plate-like tablet 3 are loaded thereon. If the coil 1 and the tablet 2 are arranged in this way, the coil 1 is arranged at an appropriate height in the molding die depending on the thickness of the flat portion of the tablet 2. And the both ends 1b of the coil 1 will be in the state pinched | interposed by the columnar convex part 2a of the tablet 2, and the inner wall face of the die | dye 4b, and the both ends 1b of the coil 1 are fixed in an appropriate position. Then, the punch 6 is set and the mold is preheated. In this embodiment, the molding die is preheated to a temperature higher than the softening temperature of the sealing material, and the tablet 2 and the plate-like tablet 3 are in a softened state.

  Next, the process of forming the core part of the manufacturing method of the first embodiment will be described. FIG. 5 is a cross-sectional view for explaining a core part forming step of the manufacturing method of the first embodiment. In addition, the cross section of FIG. 5 respond | corresponds to the AB-C-D combined cross section of FIG. As shown in FIG. 5, pressurization is performed using a punch 6 to integrate the tablet 2 and the plate-like tablet 3, and the sealing material is cured. At this time, the tablet 2 and the plate-like tablet 3 are in a softened state, and the coil 1 is easily sealed. And the both ends 1b of the coil 1 are sealed in a state where at least a part thereof is buried in the sealing material without being displaced. And the core part 7 obtained by hardening a sealing material is taken out from a shaping die. As shown in FIG. 6, the surface of the end portion 1 b of the coil 1 is exposed on the surface of the core portion 7.

  Next, the core size resizing process will be described. The core part after resizing is shown in FIG. 7 and FIG. As shown in FIGS. 7 and 8, in the first embodiment, the two side surfaces of the core portion 7 where the end portion 1 b of the coil is not exposed are polished, and the core portion 7 is resized. At this time, as shown in FIG. 7, in the core portion 7, the core portion 7 may be resized so that the area S2 of the outer peripheral portion of the coil 1 is in a range up to the area S1 of the core portion of the coil 1, and S1 and S2 It is more preferable to resize so as to be equivalent.

  Finally, a conductive resin is applied to the surface of the core portion 7 so as to be connected to the end portion 1 b exposed on the surface of the core portion 7. In this embodiment, the two side surfaces where the end portion 1b is exposed and a part of the bottom surface are applied 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 mount inductor shown in FIG. 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.

(Second embodiment)
With reference to FIGS. 10-16, the 2nd Example of the manufacturing method of the surface mount inductor of this invention is described. In the second embodiment, the same composition as that of the sealing material used in the first embodiment is used. The description of the parts common to the first embodiment is omitted.

  First, the coil used in the second embodiment will be described. FIG. 10 shows a perspective view of a coil used in the second embodiment. As shown in FIG. 10, the coil 1 is obtained by winding a rectangular wire around two stages of outer and outer windings. The end 1b was drawn out to the same side of the coil 1.

  Next, the tablet used in the second embodiment will be described. FIG. 11 is a perspective view for explaining the arrangement of the coil and tablet of the second embodiment. The tablet 12 is created using pressure molding of the sealing material. In this embodiment, the tablet 12 is used in an uncured state. As shown in FIG. 11, it forms in the shape which has the columnar convex part 12a in the periphery of a plane part so that the tablet 12 coil 11 may be enclosed. Both end portions 11b of the coil 11 are arranged along the outer side surface of the columnar convex portion 2a so that the same side surface of the tablet 12 is pulled out.

  Next, the process of arranging the coil and tablet in the molding method of the second embodiment and the process of forming the core part will be described. FIG. 12 shows the arrangement of coils and tablets in the molding die. FIG. 13 is a sectional view for explaining a part of the manufacturing process of the second embodiment. The cross section of FIG. 13 corresponds to the cross section A-B-C-D of FIG. As shown in FIGS. 12 and 13A, in the second embodiment, a molding die having a die 14 composed of a split die 14a and a split die 1b 4b, a lower die 15 and a punch 16 is used. Use. The tablet 12 in which the coil 11 is arranged is loaded into this molding die.

  Next, as shown in FIG. 13 (b), a predetermined amount of the powdery sealing material 13 is put on the coil 11 and the tablet 12, and the punch 16 is set. In this example, a powdery sealing material having the same composition as that of the tablet 12 was used. And a powdery sealing material should just shape | mold to a non-hardened or semi-hardened state similarly to a tablet.

  Next, as shown in FIG.13 (c), the tablet part 12 and the powdery sealing material 13 are integrated by the compacting method using the punch 16, and the core part 17 is formed. At this time, the tablet 12 is reshaped to seal the coil 11 together with the powdery sealing material 13. The end portion 11 b of the coil 11 is sealed with at least a portion thereof buried in the core portion 17 without being displaced. After the sealing material is cured, it is taken out from the molding die to obtain the core portion 17 shown in FIG. As shown in FIG. 14, the core portion of the present embodiment is in a state where the plane of the end portion 11 b of the coil 11 is exposed on one side surface of the core portion 17.

  Next, the core size resizing process will be described. FIG. 15 is a perspective view of the core portion after resizing. In the second embodiment, the core portion 17 is resized by cutting the three side surfaces and the upper and lower surfaces where the end portion 11b of the coil of the core portion 17 is not exposed. In the present embodiment, the core portion is further reduced in size and reduced in height. At this time, similarly to the first embodiment, the side surface to be cut may be resized so that the area of the outer peripheral portion of the coil is in the range up to the area of the core portion of the coil. In addition, it is sufficient to ensure the minimum cross-sectional integral through which the magnetic flux passes for the upper and lower surfaces, and the area obtained by multiplying the circumference of the coil core by the height of the top surface or the bottom surface from the coil is the area of the coil core. Equivalent to or better than. In the case of this example, the core portion was cut so that the product of the circumference of the elliptical core portion and the height from the coil to the top surface or the bottom surface was 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 1b. Subsequently, a plating process is performed to form the external electrode 18 to obtain the surface mount inductor shown in FIG.

  In the said Example, the iron-type metal magnetic powder was used for the filler as a sealing material, and the epoxy resin was used for resin. By using iron-based metal magnetic powder, a surface-mount inductor having excellent DC superposition characteristics can be produced. However, not limited to this, for example, ferrite magnetic powder or glass powder may be used as the filler. Further, a thermosetting resin such as a polyimide resin or a phenol resin, or a thermoplastic resin such as a polyethylene resin or a polyamide resin may be used as the resin. In addition, the core part may be formed by combining cores using different materials such as ferrite cores. However, when the surface of the core part is formed of the same material when polishing or the like, Since the stress applied to is uniform, it is excellent in workability.

  In the above embodiment, an air-core coil wound in two stages of outer and outer windings is used as the coil. However, the present invention is not limited to this. For example, a winding method such as edgewise winding or a coil having a circular, rectangular, or trapezoidal shape is used. It may be used.

  In the first embodiment, a plate-like tablet is used, but it may be preformed into a shape such as a T shape or an E shape without being limited to a plate shape. Moreover, not a non-hardened state but a semi-hardened state may be sufficient. The molding method may be appropriately selected according to the application such as a pressure molding method or cutting out from a sheet-like molded product.

1, 11: Coil (1a, 11a: winding part, 1b, 11b: end part)
2, 12: Tablet 3: Plate-shaped tablet 4, 14: Die (4a, 4b, 14a, 14b: Split die)
5, 15: Lower mold 6, 16: Punch 7, 17: Core part 8, 18: External electrode 13: Powdery sealing material

Claims (3)

In a method for manufacturing a surface mount inductor in which a coil is sealed with a sealing material including a resin and a filler using a molding die,
A step of preforming the sealing material into a shape having a columnar convex portion at a peripheral edge portion of a flat plate shape to form a tablet;
Forming a coil by winding a conducting wire having a flat cross section; and
Placing the coil on the tablet, placing both ends of the coil along the outer side surface of the columnar convex portion of the tablet in the mold,
Using the resin molding method or the powder molding method for the coil and the sealing material with both end portions of the coil being sandwiched between the outer side surface of the columnar convex portion of the tablet and the inner wall surface of the molding die And forming a core part by integrating them,
Polishing or cutting at least one surface of the core portion other than the surface where both ends of the coil are exposed, and resizing the core portion;
A method for manufacturing a surface-mount inductor, comprising a step of providing, on the surface or outer periphery of the core portion, an external electrode connected to a portion where at least a part of both ends of the coil is exposed on the surface of the core portion.   The method for manufacturing a surface-mount inductor according to claim 1, wherein the filler is magnetic powder. In the step of resizing the core part,
3. The surface-mount inductor according to claim 1, wherein the core portion is resized so that an area of an outer peripheral portion of the coil in the core portion is not smaller than an area of a core portion of the coil. Production method.

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