JP5329202B2 - Molded coil manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a molded coil, and more particularly to a method for sealing an air-core coil with a magnetic mold resin.

  Conventionally, a molded coil in which a coil is sealed with a magnetic mold resin obtained by kneading magnetic powder and resin has been widely used. In a conventional method of manufacturing a molded coil, a coil wound around a core such as a ferrite core is placed in a cavity of a mold, and then the molten magnetic mold resin is filled in the cavity to seal the coil. . Patent Document 1 and Patent Document 2 disclose a method of manufacturing a molded coil using a winding core.

For example, when trying to seal an air core coil without using a winding core with a magnetic mold resin as it is, the air core coil is deformed by the filling pressure of the magnetic mold resin, or it is inclined to one side in the cavity or tilted. Sometimes deviated from a predetermined position. These deformation and misalignment of the coils not only cause appearance defects, but also affect electrical characteristics such as inductance values and DC superimposition characteristics. Therefore, conventionally, in order to prevent deformation and displacement of the coil, it has been common to use a winding core, a frame, or the like.
JP-A-4-338613 JP 2006-32847 A

  In recent years, technological innovation for downsizing and high functionality of electronic devices has been remarkable, and accordingly, electronic components such as molded coils are also demanded for downsizing, high performance, and low price. However, the cores and frames used in the conventional mold coil hinder the miniaturization and low profile of the mold coil, and further increase the cost.

  Therefore, the applicant has proposed a method for manufacturing a molded coil that does not require a winding core or a frame using a molding die having a positioning pin and a support pin in Japanese Patent Application No. 2008-97874 filed earlier. However, when this method is used, if the shape of the inner diameter of the air-core coil is a shape close to a perfect circle (hereinafter referred to as a substantially perfect circle), the air-core coil is placed in the cavity of the molding die or in the cavity. When the magnetic mold resin is filled in, the air-core coil 101 sometimes rotates around the positioning pin 103a as shown in FIG. If the air-core coil is sealed while being rotated, the end of the coil may be shifted to an inappropriate position or the coil may be distorted. In addition, when integral molding is performed with the external electrode attached to the end of the coil by spot welding or the like, the external electrode may be distorted if the external electrode is made of a material such as metal foil. If the magnetic mold resin is filled while the coil is rotating, stress is applied to the connection portion between the external electrode and the end portion of the coil, and in the worst case, there is a possibility of causing molding defects such as disconnection. .

  An object of the present invention is to provide a method for manufacturing a molded coil that is small in size and excellent in mass productivity and has few molding defects.

In order to solve the above-described problems, the mold coil manufacturing method of the present invention uses a plastic molding method to seal an air-core coil with a magnetic mold resin obtained by kneading a magnetic powder and a resin. An air-core coil whose shape is not substantially circular is used. A molding die having a cavity formed from a plurality of molds and a positioning pin movable in the vertical direction in the cavity is used, and includes the following operations.
(A) An air core coil is arranged at a predetermined position in the cavity by a positioning pin.
(B) Fill the cavity with a magnetic mold resin.
(C) During the filling, the positioning pin is moved to a predetermined position.

  In the mold coil manufacturing method of the present invention, a cavity formed from a plurality of molds, a molding die having positioning pins that can move in the vertical direction in the cavity, and an air core coil that is not substantially circular in shape Is used. Therefore, the air-core coil is positioned at an appropriate position in the cavity by the positioning pin in the cavity. Further, since an air core coil whose inner diameter is not substantially circular is used, it does not rotate in the cavity. Thereby, a mold coil with high forming accuracy can be formed.

(First embodiment)
A first embodiment of a method for manufacturing a molded coil according to the present invention will be described with reference to FIGS. In the drawings, reference numeral 1 denotes an air core coil, 2 denotes an upper die, 3 denotes a lower die, 4 denotes a cavity, 5 denotes a magnetic mold resin, 6 denotes a punch, and 7 denotes an external electrode.

  First, the air-core coil 1 used in the first embodiment will be described. FIG. 1 shows a perspective view of an air-core coil 1 used in the first embodiment. The air-core coil 1 uses a self-bonding rectangular wire having a width of 0.25 mm and a thickness of 0.06 mm, and a core material having an elliptical cross section and wound by 12 turns with external and external windings. Use.

  Next, the molding die used in the present embodiment will be described. FIG. 2 shows a molding die used in the embodiment of the present invention, FIG. 2 (a) is a top view, and FIG. 2 (b) is a cross-sectional view taken along line AA of FIG. 2 (a). As shown in FIG. 2, the molding die used in this embodiment has an upper die 2 and a lower die 3, and the cavity 4 is formed by combining the upper die 2 and the lower die 3. The lower mold 3 is combined with the upper mold 2 to form the bottom of the cavity 4. Further, the lower die 3 is provided with a positioning pin 3a and a support pin 3b which can be moved up and down (movable in the vertical direction) in the vertical direction of the cavity 4 protruding toward the opening of the cavity 4 at the bottom of the cavity 4.

  In this embodiment, the positioning pin 3a is a columnar metal bar having an oval cross section and a diameter 20 μm smaller than the core material when the air-core coil 1 is formed. A cylindrical metal rod having a diameter of 0.4 mm was used as the support pin 3b. The positioning pin 3a has a height h1 protruding from the bottom of the cavity 4 set to 0.75 mm as an initial state, and the support pin 3b has a height h2 protruding from the bottom of the cavity 4 to 0.38 mm as an initial state. Set.

  Next, a method for manufacturing the molded coil of the first embodiment will be described. FIG. 3 is a top view showing the arrangement of the air-core coil according to the first embodiment of the present invention. 4 and 5 show the main part of the manufacturing process of the molded coil of the first embodiment. FIG. 6 shows a perspective view of the molded coil of the first embodiment of the present invention. 4 and 5 show cross sections at each stage in the AA cross sectional view of FIG.

  As shown in FIGS. 3 and 4 (a), the air-core coil 1 is placed in the cavity 4, and the molding dies (upper mold 2 and lower mold 3) are preheated at 180 ° C. At this time, the air-core coil 1 is arranged such that the positioning pin 3a is inserted into the inner diameter portion of the air-core coil 1, and the bottom surface of the air-core coil 1 is placed on the support pin 3b. Thus, the air core coil 1 is fixed by the positioning pin 3a without rotating in the horizontal direction in the cavity 4, and is held hollow by the support pin 3b. Further, the preheating temperature may be set to a temperature at which the magnetic mold resin can be softened (a temperature equal to or higher than the softening temperature of the resin in the magnetic mold resin), and is set to 180 ° C. in this embodiment.

  As shown in FIG. 4B, a magnetic mold resin 5 weighed in a predetermined amount from the opening of the upper mold 2 onto the air core coil 1 is put into the cavity 4, and the magnetic mold is preheated by the molding die. Resin 5 is melted. In this embodiment, the magnetic mold resin 5 is a powdery material obtained by kneading and dispersing an amorphous alloy powder and a novolac-type epoxy resin, and cooling and kneading the kneaded product. In addition, it prepared so that the filling rate of the amorphous alloy powder in magnetic body resin might be set to 60 Vol%.

  As shown in FIG. 4 (c), the punch 6 is set in the opening of the upper mold 2. Next, as shown in FIG. 5A, the punch 6 is pressurized with 3 kgf for 5 seconds. Next, as shown in FIG. 5B, the positioning pin 3 a is lowered to the position of the bottom of the cavity 4, and then pressurized with a punch 6 at 5 kgf for 20 seconds. If it does in this way, the magnetic body mold resin 5 will be filled in the part with the positioning pin 3a. Next, after the pressurization from the punch 6 is stopped and the punch 6 is brought into a free state, the support pin 3b is lowered to the position of the bottom of the cavity 4 as shown in FIG. Subsequently, the punch 6 is again pressurized with 10 kgf for 20 seconds. If it does in this way, the magnetic body mold resin 5 will be filled in the part with the support pin 3b. Thereafter, the magnetic mold resin 5 is hardened by heating at 180 ° C. for 10 minutes.

  The molded body obtained by curing the magnetic mold resin 5 is taken out of the molding die, deburred by sandblasting, and the end of the air-core coil 1 is exposed. The molded body is covered with an epoxy resin except for the portion where the external electrode is formed. The external electrode 7 is formed by plating so as to connect to the exposed end portion of the air-core coil 1 to obtain a molded coil as shown in FIG.

(Second embodiment)
A second embodiment of the method for producing a molded coil according to the present invention will be described with reference to FIGS. FIG. 7 is a view showing a coil member used in the second embodiment of the present invention. FIG. 8 is a view showing the arrangement of air-core coils according to the second embodiment of the present invention. FIG. 9 is a view showing a molded coil according to a second embodiment of the present invention. In the second embodiment, a method of integrally forming simultaneously with an air-core coil using a metal foil as an external electrode will be described. In the second embodiment, the molding die used in the first embodiment is used, and the description of the parts common to the first embodiment is omitted.

  The air-core coil 1 and metal foil 8 used in the first example were spot welded to obtain a coil member as shown in FIG. As shown in FIG. 8, the positioning pin 3 a is inserted into the inner diameter portion of the air-core coil 1, and the coil member is disposed so that the metal foil 8 is on the bottom side of the cavity 4. At this time, the air-core coil 1 formed in an oval shape is properly arranged without rotating by the positioning pin 3a. After arranging the coil member, the operation described with reference to FIGS. 4 and 5 in the first embodiment was performed, and the coil member was sealed with a magnetic mold resin and cured. A molded body obtained by curing the magnetic mold resin is taken out from the molding die, deburred by sandblasting, and the end of the air-core coil 1 and the metal foil 8 are exposed. The molded body is dipped in a solder bath so as to be connected to both the exposed end portion of the air-core coil 1 and the metal foil 8 to form a solder layer 9 to obtain a molded coil as shown in FIG.

(Third embodiment)
A third embodiment of the method for manufacturing a molded coil according to the present invention will be described with reference to FIGS. The third embodiment shows a method using a molding die provided with positioning pins on the side surface of the cavity. In the third embodiment, the magnetic mold resin and the rectangular wire used in the first embodiment are used, and the description of the parts common to the first embodiment is omitted.

  First, the air core coil used in the present embodiment will be described. FIG. 10 shows a perspective view of an air core coil used in the third embodiment. Using the rectangular wire and the core material used in the first example, 12 turns were wound by external and external winding. Furthermore, both ends of the flat wire were drawn out in the same direction, and the ends were bent to obtain an air-core coil 10 shown in FIG.

  Next, a molding die used in the third embodiment will be described. FIG. 11 shows a molding die used in the third embodiment of the present invention, where (a) shows a top view and (b) shows a front view. As shown in FIG. 11, the molding die used in the third embodiment has an upper die 11 and a lower die 12, and a cavity 13 is formed by combining the upper die 11 and the lower die 12. A positioning pin 11 a protruding into the cavity 13 is provided on one of the side surfaces of the upper mold 11. At this time, the positioning pin 11a protrudes into the cavity 11 in the direction of the side surface facing the side surface where the positioning pin 11a is provided, and can move in the front-rear direction of the protruding direction (the horizontal direction of the cavity 13). Like that. In the present embodiment, as in the first embodiment, a columnar metal rod having a diameter 20 μm smaller than the core material is used for the positioning pin 11 a, and the center thereof is positioned 1.0 mm from the bottom of the cavity 13. The upper die 11 was provided.

  Next, a method for manufacturing the molded coil of the first embodiment will be described. 12 to 15 show the main part of the manufacturing process of the molded coil of the third embodiment. FIG. 16 is a perspective view of a molded coil according to an embodiment of the present invention. In addition, FIGS. 12-15 shows the top view and front view in each process, (a) is a top view, (b) is a front view.

  As shown in FIG. 12, the air-core coil 10 is placed in the cavity 13 and the molding die is preheated at 180 ° C. At this time, the positioning pin 11 a is inserted into the inner diameter portion of the air-core coil 10. As shown in FIG. 13, a magnetic mold resin 14 weighed in a predetermined amount from the opening of the upper mold 11 onto the air core coil 10 is put into the cavity 13, and the magnetic mold resin 14 is preheated by the molding die. Melt.

  As shown in FIG. 14, the punch 15 is set in the opening of the upper mold 11 and is pressurized with 5 kgf for 5 seconds using the punch 15. The air-core coil 10 is sealed with the magnetic molding resin 14 except for a portion where the positioning pin 11a is provided. Next, after the pressurization from the punch 15 is stopped and the punch 15 is brought into a free state, the positioning pin 11a is positioned so that the end thereof is positioned at the side surface of the cavity 13 as shown in FIG. Move. Further, as shown in FIG. 15B, the punch 15 is pressurized with 10 kgf for 20 seconds. In this way, the magnetic mold resin 14 is filled in the portion where the positioning pin 11a was present. Thereafter, the magnetic mold resin 14 is cured by heating at 180 ° C. for 10 minutes.

  The molded body obtained by curing the magnetic mold resin 14 is taken out of the molding die and deburred by sandblasting, and the end of the air-core coil 10 is exposed on the side surface of the molded body. The molded body is covered with an epoxy resin except for the portion where the external electrode is formed. The external electrode 16 is formed by plating so as to connect to the exposed end portion of the air-core coil 10 to obtain a molded coil as shown in FIG.

  In the above embodiment, an elliptical air-core coil is used. However, the present invention is not limited to this, and any shape other than a substantially perfect circle can be used. For example, it can be implemented in a semicircular shape, a fan shape, an elliptical shape, a substantially polygonal shape, or a combination thereof. In the above embodiment, one positioning pin having an oval cross-sectional shape is used. However, the present invention is not limited to this. A pin may be used.

  In this embodiment, the molded coil is formed by using the compression molding method, but the present invention can also be carried out by using other plastic molding methods such as a transfer molding method and an injection molding method.

It is a figure which shows the coil used in the 1st Example of this invention. It is a figure which shows the molding die used in the Example of this invention, (a) is a top view, (b) is AA sectional drawing of (a). It is a figure which shows arrangement | positioning of the air-core coil of 1st Example of this invention. It is a figure explaining the manufacturing method of the mold coil of the 1st Example of the present invention. It is a figure explaining the manufacturing method of the mold coil of the 1st Example of the present invention. It is a figure which shows the mold coil of the 1st Example of this invention. It is a figure which shows the coil member used in the 2nd Example of this invention. It is a figure which shows arrangement | positioning of the coil member of 2nd Example of this invention. It is a figure which shows the mold coil of the 2nd Example of this invention. It is a figure which shows the coil used in the 3rd Example of this invention. It is a figure which shows the shaping die used in the 3rd Example of this invention, (a) is a top view, (b) is a front view. It is a figure which shows arrangement | positioning of the air-core coil of the 3rd Example of this invention, (a) is a top view, (b) is a front view. It is a figure explaining the manufacturing method of the molded coil of the 3rd Example of this invention, (a) is a top view, (b) is a front view. It is a figure explaining the manufacturing method of the molded coil of the 3rd Example of this invention, (a) is a top view, (b) is a front view. It is a figure explaining the manufacturing method of the molded coil of the 3rd Example of this invention, (a) is a top view, (b) is a front view. It is a figure which shows the mold coil of the 3rd Example of this invention. It is a top view which shows arrangement | positioning of the conventional air core coil.

Explanation of symbols

1: air core coil, 2: upper mold, 3 lower mold, 3a: positioning pin, 3b: support pin, 4: cavity, 5 magnetic mold resin, 6: punch, 7: external electrode, 8: metal foil, 9: Solder layer, 10: Air core coil, 11: Upper die, 11a: Positioning pin, 12: Lower die, 13: Cavity, 14: Magnetic molding resin, 15: Punch, 16: External electrode

Claims (4)

In a method for producing a molded coil, in which an air-core coil is sealed with a magnetic molding resin in which magnetic powder and resin are kneaded using a plastic molding method,
The flat wire wound so as to both ends thereof positioned on the outer peripheral, and to form an air core coil shape is not substantially a perfect circle shape, Ru attaching an external electrode to the air core coil process,
A cavity formed from a plurality of molds, a positioning pin that is vertically movable in the cavity projecting from the bottom of the cavity, and a cavity projecting from the bottom of the cavity A mold having a pair of support pins movable in the vertical direction is used, and the pair of support pins and the positioning pins are supported from the bottom of the cavity so that the positioning pins protrude from the pair of support pins. With the pin protruding, the air core coil is disposed in the cavity , and the horizontal direction of the cavity is fixed by the positioning pin inserted into the hollow portion of the air core coil. Hollow holding with the set of support pins in contact with the bottom surface ;
The positioning after filling the molded metal mold magnetic molding resin magnetic powder to the positioning pin and the portion other than the support pins in the cavity is filled more than 60 vol% in the magnetic body mold resin After the pin is lowered to a predetermined position, pressure is applied by the punch of the molding die to fill the magnetic mold resin in the initial position portion of the positioning pin in the cavity, and then the support pin is fixed. A step of lowering to the position of the mold, applying pressure by the punch of the molding die , filling the portion of the support pin in the initial position of the support pin with the magnetic mold resin, and heating and curing to form a molded body; ,
A method for producing a molded coil, comprising a step of deburring the molded body to form an external electrode connected to the air-core coil on the surface of the molded body. The method of manufacturing a molded coil according to claim 1, wherein the air-core coil has a semicircular shape, a fan shape, an oval shape, an elliptical shape, a substantially polygonal shape, or a shape obtained by combining them. In a method for producing a molded coil, in which an air-core coil is sealed with a magnetic molding resin in which magnetic powder and resin are kneaded using a plastic molding method,
An air core in which a flat wire is wound so that both ends thereof are positioned on the outer periphery, the lead-out portion is pulled out in the same direction, and the end portion is bent to have a bent portion. Forming a coil;
A cavity formed by combining upper and lower molds, a mold having a positioning pin is not movable within the cavity in the horizontal direction on the side surface of the upper mold section is substantially a perfect circle shape using, The positioning pin is inserted into the hollow portion of the air-core coil, and the air-core coil is placed in the cavity so that the winding axis is parallel to the lower die surface and the bent portion is in contact with the lower die surface . A process of arranging in
After the magnetic mold resin is filled with 60% or more by volume of the magnetic powder in the magnetic material molding resin, the positioning pin is set to a predetermined position in the cavity other than the positioning pin in the cavity. A step of forming the molded body by applying pressure by the punch of the molding die, filling the magnetic mold resin in the initial position portion of the positioning pin in the cavity, and heating and curing the resin. When,
And comprising the step of exposing the bent portion of the air core coil to the surface of the molded body is subjected to deburring on the molded article, it is formed an external electrode connected to the air core coil to the molded article A method for manufacturing a molded coil. The method of manufacturing a molded coil according to claim 3, wherein the shape of the air-core coil is any one of a semicircle, a fan, an oval, an ellipse, a substantially polygon, or a combination thereof.

Images