JP2015035633A - Coil component and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coil component with an excellent magnetic efficiency and reliability by entirely increasing the density of magnetic core.SOLUTION: The coil component includes: a magnetic core 16 formed by pressuring a magnetic material 15 of a mixture of a powder of metal magnetic substance and a binding material; and a coil 12 of a conductor wire which is spirally wound and embedded in the magnetic core 16. The coil component has a winding shaft of the coil 12. When viewing the cross section with the winding shaft vertical, the dimension of central portion between the inner periphery and an outer periphery of the coil 12 in the winding shaft direction is larger the dimension between the inner periphery and outer periphery of the coil 12 in the winding shaft direction. With this arrangement, the magnetic material 15 flows well when forming and pressing, and uniform density is achieved; and thus, a high reliable coil component superior in electric characteristics is achieved.

Description

  The present invention relates to a coil component used in various electronic devices.

  In recent years, electronic devices incorporating LSIs such as CPUs typified by notebook computers have become lighter, thinner, and smaller, and power supply circuit units such as DC / DC converters that drive these electronic devices have increased in driving frequency from 300 kHz to 1 MHz. In addition, the electronic components to be mounted are reduced in size and thickness by increasing the driving power supply at low voltage and high current, etc., so that the electronic devices can be made light and thin.

  Coil parts such as choke coils used in such power supply circuit sections have reduced eddy current loss for high-frequency currents by powdering a metal magnetic material mainly composed of iron, which has a saturation magnetic flux density higher than that of ferrite. By using metal magnetic powder and embedding a coil in a magnetic material that is a mixture of this metal magnetic powder and a thermosetting resin binder, it is compact, thin, and capable of handling high-frequency, high-current applications. doing.

  Next, such a conventional coil component will be described with reference to the drawings.

  12 is a transparent perspective view of a conventional coil component, and FIG. 13 is a cross-sectional view taken along line AA of FIG.

As shown in FIGS. 12 and 13, a conventional coil component includes a coil 2 in which an insulating film copper wire having a hollow core 1 at the center is wound, and lead wires 3 at both ends of the coil 2, A terminal 4 formed by processing a conductive metal flat plate connected to the lead wire 3, a metal magnetic powder made of a metal magnetic material containing iron as a main component, and a thermosetting resin are mixed. It consists of a magnetic core 6 formed by pressing a magnetic material 5 granulated into a granule, and a part of the coil 2 and the terminal 4 are placed in a molding die (not shown). After the mold 2 is filled with the magnetic material 5 so as to cover the coil 2 and part of the terminal 4, the coil 2 is pressed by punching (not shown) in the vertical direction of the coil 2 to 2-4 t / cm ^2. 2 is embedded, and the pressure-molded magnetic core 6 is 150 to 180 ° C. After curing the thermosetting resin is subjected to a heat treatment of 1 to 2 hours in degrees, it constituted the coil component by bending toward the terminal 4 from the side of the magnetic core 6 to the bottom surface.

  As prior art document information related to the invention of this application, for example, Patent Document 1 is known.

JP 2003-217941 A

  In the above-described conventional coil component, the coil 2 is embedded in the magnetic material 5 granulated into a granule and press-molded. Therefore, the magnetic material 5 positioned on the upper surface and the lower surface of the coil 2 as pressed by the punch Since the degree of compression becomes larger and stronger than the magnetic material 5 in the core 1 of the coil 2 and the outer peripheral portion of the coil 2, the strong portions of the magnetic material 5 on the upper surface and the lower surface of the coil 2 This has hindered sufficient pressurization of the magnetic material 5 on the core portion 1 without the coil 2 and the outer peripheral portion of the coil 2. That is, since the degree of compression is smaller in the core portion 1 and the outer peripheral portion where there is no coil than in the upper and lower portions of the coil, the density of the magnetic core 6 in the core portion 1 is reduced, and as a result, the magnetic efficiency is improved. It will be bad.

  Further, since the density of the magnetic material 5 is small in the core portion 1 without the coil 2 and the outer peripheral portion of the coil 2 where the degree of compression becomes small, the insulation coating of the coil 2 when the magnetic core 6 is heat-treated The crack 7 is likely to occur due to the stress in the vertical direction generated by the thermal expansion of the resin of the resin, and the crack 7 is formed near the center of the height of the coil 2 of the coil 2 as shown in FIG. As shown in FIG. 14, the crack 7 is likely to occur from the vicinity of the edge portion of the embedded portion of the terminal 4 in the outer peripheral portion of the coil 2.

  The present invention solves the above-mentioned conventional problems. In a coil component in which a coil is embedded in a magnetic core made of a metal magnetic powder, the magnetic efficiency is increased by increasing the density of the magnetic metal powder of the magnetic core as a whole. It is an object of the present invention to provide a highly reliable coil component that suppresses the occurrence of cracks in the magnetic core.

  In order to solve the above problems, the present invention provides a magnetic core formed by mixing metal magnetic powder and a binder and press-molding, and a coil formed by spirally winding a conductive wire embedded in the magnetic core. When the cross section including the winding axis of the coil is taken up and down, the dimensions in the direction of the winding axis of the central portion between the inner periphery and the outer periphery of the coil are determined. Is larger than the dimension in the winding axis direction.

  With the above configuration, the metal magnetic powder can easily flow into the core and the outer periphery during pressure molding, and the overall density of the magnetic metal powder can be increased. Electrical characteristics and reliability Can be obtained.

1 is a transparent perspective view of a coil component according to an embodiment of the present invention. BB sectional view of FIG. Sectional drawing of the insulation film copper wire with a fusion | melting layer in one embodiment of this invention Sectional drawing of the coil which shows the other example in one embodiment of this invention Sectional drawing of the coil which shows the other example in one embodiment of this invention The figure explaining the manufacturing method of the coil components in one embodiment of this invention The figure explaining the manufacturing method of the coil components in one embodiment of this invention The figure explaining the manufacturing method of the coil components in one embodiment of this invention The figure explaining the manufacturing method of the coil components in one embodiment of this invention The figure explaining the manufacturing method of the coil components in one embodiment of this invention The figure explaining the manufacturing method of the coil components in one embodiment of this invention Transparent perspective view of conventional coil components AA line sectional view of FIG. Terminal side view of conventional coil components

  Hereinafter, a coil component according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a transparent perspective view of a coil component according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line BB in FIG. FIG. 2 shows a cross-sectional view of the coil cut along a plane including the winding axis and viewed with the winding axis up and down. As shown in FIGS. 1 and 2, the coil component in one embodiment of the present invention is formed by spirally winding an insulating film copper wire 21 having an insulating coating on the surface, and has a hollow core 11 in the center. A coil 12 having a lead wire, lead wires 13 at both ends of the coil 12, terminals 14 made of a metal plate such as a phosphor bronze plate connected to the lead wire 13, and a metal magnetic material containing iron as a main component. A magnetic core 16 made of a magnetic material 15 is prepared by mixing a metallic magnetic powder and a binder made of a thermosetting resin such as an epoxy resin, and granulating the binder. A magnetic core 16 is formed integrally with the coil 12 by embedding a part in the magnetic material 15 and press-molding, and the thermoset resin as a binder is cured by heat-treating the press-molded magnetic core 16. After that, exposed from the side of the magnetic core 16 Constitute a coil component to the terminal 14 from the side surface of the magnetic core 16 is subjected to bending toward the bottom.

  In order to maintain the shape of the coil 12 when the coil 12 is embedded in the magnetic material 15 and press-molded, as shown in FIG. 3, an insulating layer 18 made of an insulating resin is provided on the surface of the copper wire 17. It is desirable to use an insulating film copper wire 21 with a fusion layer 19 in which a fusion layer 19 made of epoxy resin or the like is coated on the surface of the insulation film copper wire 21 coated with It is good to fix with the layer 19.

  Here, as shown in FIG. 2, the outer shape of the cross section of the coil 12 is such that b <a, where the width a of the central portion is the width b of the upper and lower ends. By doing in this way, since it can incline toward the center direction of a winding axis | shaft from the upper and lower parts of the coil 12 on the external shape of the cross section of the coil 12, the magnetic material 15 granulated into the granule is pressure-molded. When the pressure is applied, the magnetic material 15 easily flows from the upper surface and the lower surface of the coil 12 to the core portion 11 and the outer peripheral portion by the pressure, and the magnetic material 15 positioned on the upper surface and the lower surface of the coil 12 It is possible to prevent the core 11 and the outer peripheral portion from being strongly compressed before increasing the density of the magnetic core 16, and the density becomes uniform, so that cracks and the like are less likely to occur.

  Further, when the magnetic core 16 formed by pressure is heat-treated to thermally cure the binder, the resin of the insulating layer 18 of the insulating coating copper wire 21 and the resin of the fusion layer 19 are thermally expanded, and the magnetic core 16 Stress is generated in the vertical direction. At this time, the insulating film copper wire 21 on which the coil 12 is formed has a cross-sectional shape of the insulating film copper wire 21 between the adjacent insulating film copper wires 21 as shown in FIG. Since it is deformed into a shape and is in close contact, it is easily affected by the thermal expansion stress of the resin of the insulating layer 18 and the fusion layer 19. The stress due to the thermal expansion is likely to be concentrated in the vertical direction of the magnetic core 6 when the coil 2 has a rectangular cross-sectional shape as in a conventional coil component, and cracks are likely to occur in the magnetic core 6. However, since the upper and lower portions of the coil 12 are inclined as in the present invention, the direction of stress due to thermal expansion can be dispersed as shown by the arrow c in FIG. Cracks are less likely to occur in the core 11 and the outer periphery.

  Furthermore, compared with the conventional coil component having a rectangular cross-sectional outer shape, the coil 12 has a cross-section of the coil 12 with respect to the same number of turns. Since the magnetic path length around the periphery can be shortened, the magnetic efficiency can be improved and the electrical characteristics can be improved.

  In order to improve the flow of the magnetic material 15 granulated into granules, it is preferable to widen the inclined areas of the upper and lower portions of the coil 12, and it is more preferable that 2b ≦ a.

  Further, in the present embodiment, the outer shape of the cross section of the coil 12 has been described as a hexagonal shape (the shape indicated by the broken line in FIG. 2), but the other in the embodiment of the present invention of FIGS. As shown in the cross-sectional view of the coil shown in FIG. 5, the same effect as that of the present embodiment can be obtained by using the diamond shape shown in FIG. 4 or the octagonal shape shown in FIG.

  Next, the manufacturing method of the coil component in one embodiment of this invention is demonstrated using FIGS.

  First, the insulating film copper wire 21 having a diameter of about 0.12 mm is passed through the nozzle 20, and the coil 12 is formed by rotating the winding shaft 23 and winding the insulating film copper wire 21 a predetermined number of times (FIG. 6). Here, an insulating layer 18 made of polyimide amide as an insulating material is formed with a thickness of 0.01 mm on the surface of the copper wire 17 of the insulating coating copper wire 21, and further fused on the surface thereof with an uncured epoxy resin. Layer 19 is formed with a thickness of 0.005 mm. Further, the winding shaft 23 has a shape in which cones are joined so as to be thin at the center portion, and has a split shape that can be divided at the center portion.

  The coil 12 starts to be wound from the narrowest portion of the winding shaft 23, winds the insulating coating copper wire 21 in alignment while moving the nozzle 20, winds the entire width of the winding shaft 23, and then further outwards. The insulating coating copper wire 21 is overlaid on the winding shaft 23 and wound around the entire width of the winding shaft 23. By repeating this a predetermined number of times and winding the insulating film copper wire 21 in accordance with the shape of the winding shaft 23, the cross-sectional shape of the outer shape of the coil 12 spreads from the center side of the winding axis toward the upper and lower portions of the coil 12. In this way, an inclined portion is formed, and then the winding width of the nozzle 20 is wound for each winding layer on which the insulating coating copper wire 21 is overlapped on the outside, and this is repeated a predetermined number of times, thereby repeating the outer shape of the coil 12. An inclined portion is formed so that the cross-sectional shape becomes narrower from the upper and lower portions toward the center side of the winding shaft. At this time, the insulating coating copper wire 21 is wound while hot air is applied to the winding shaft 23 so that the temperature of the insulating coating copper wire 21 wound around the winding shaft 23 is about 160 to 180 ° C. By doing so, the insulating coating copper wire 21 is wound while the fusion layer 19 is cured, so that the shape of the coil 12 does not collapse even when the coil 12 inclined from the upper and lower parts toward the center side is formed.

  Thereafter, the winding shaft 23 is separated at the central portion and is detached from the winding shaft 23, whereby the coil 12 having an inclination from the upper and lower portions toward the center of the winding shaft as shown in FIG. 7 is obtained. Can do. Also at this time, the outer shape of the cross section of the coil 12 is such that the width of the central portion is larger than the width of the upper and lower ends, but the shape of the coil 12 is fixed because each other is fixed by the fusion layer 19. Will not collapse.

  Next, the lead wire 13 of the coil 12 is connected to the terminal 14 formed by processing a metal flat plate such as a phosphor bronze plate by electric welding or the like (FIG. 8). The terminal 14 may be formed as a single piece or in a continuous hoop shape, and it is desirable to form a continuous hoop shape in consideration of productivity.

Next, a die having an upper die 25 and a lower die 26 having a through hole 24, and an upper punch 27 and a lower punch 28 which are inserted into the through hole 24 and slidable (FIG. 9A). )), The terminal 14 is sandwiched and supported by the upper die 25 and the lower die 26, and the coil 12 is placed in the die (FIG. 9B). Then, the lower punch 28 is arranged at a predetermined position, and a metal magnetic powder made of a metal magnetic material containing iron as a main component and a binder made of a thermosetting resin such as an epoxy resin are mixed, and this is granulated. A predetermined amount of the magnetic material 15 granulated in a shape is filled in the mold (FIG. 9C). Thereafter, the upper punch 27 and the lower punch 28 are press-formed in the winding axis direction of the coil 12 (in the direction of the arrow in FIG. 9D) from above and below with a pressing force of ² to 4 t / cm ² to thereby form the magnetic core 16. Is formed (FIG. 9D). At this time, since the upper and lower portions of the outer shape of the cross section of the coil 12 are inclined, the magnetic material 15 granulated into a granular shape becomes magnetic as it is pressed by the upper punch 27 and the lower punch 28 when pressed. The material 15 can easily flow from the upper surface and the lower surface of the coil 12 to the core portion 11 and the outer peripheral portion, so that the density of the magnetic core 16 can be increased as a whole. Is less likely to occur.

  Next, the pressure-molded magnetic core 16 is taken out from the mold (FIG. 10), and heat treatment is performed at 160 to 180 ° C./1 to 2 hours to cure the binder of the magnetic material 15.

  Finally, an excessive portion of the hoop-shaped terminal 14 is cut at a predetermined position and bent from the side surface of the magnetic core 16 toward the bottom surface (FIG. 11), whereby a coil component can be obtained.

  In the coil component according to the present invention, it is industrially useful to obtain a coil component that can increase the density of the magnetic metal powder of the magnetic core as a whole and has excellent electrical characteristics and reliability.

DESCRIPTION OF SYMBOLS 11 Middle core part 12 Coil 13 Lead wire 14 Terminal 15 Magnetic material 16 Magnetic core 17 Copper wire 18 Insulation layer 19 Fusion layer 20 Nozzle 21 Insulation film copper wire 23 Winding shaft 24 Through-hole 25 Upper die 26 Lower die Mold 27 Upper punch 28 Lower punch

Claims (4)

A magnetic core formed by mixing metal magnetic powder and a binder and press-molding, and a coil formed by spirally winding a conductive wire embedded in the magnetic core, and a winding axis of the coil Including the dimensions of the winding axis direction of the central portion of the inner periphery and outer periphery of the coil when the cross section with the winding axis up and down is viewed, and the winding axis direction of the inner periphery and outer periphery of the coil Coil parts larger than the dimensions of A coil component in which the outer shape of the cross section of the coil is a hexagonal shape, a rhombus shape, or an octagonal shape. A coil component comprising: a step of forming a coil by winding a conducting wire having a circular cross-sectional shape; and a step of forming a magnetic core formed by pressing and embedding the coil in a mixture of a metal magnetic powder and a binder. The method of forming the coil includes the step of passing the conductive wire through a nozzle movable in the winding axis direction of the coil, and a plurality of the conductive wires from an inner peripheral side to an outer peripheral side on a rotating winding shaft. The layer is wound, and the shaft can be divided at the central part in the winding axis direction of the coil, and the central part of the winding axis is thin and is formed so as to become thicker as the distance from the central part increases. The nozzle is moved from the thinnest part of the winding shaft to the shape of the winding shaft on the inner peripheral side of the coil to wind the conductive wire in a plurality of layers, and the nozzle is wound for each winding layer on the outer peripheral side of the coil. Movement width By winding the conducting wire while narrowing in the direction of the center side, when a cross section including the winding axis of the coil and including the winding axis up and down is viewed, the central portion between the inner periphery and the outer periphery of the coil The dimensions of the winding axis of the coil are formed larger than the dimensions of the inner and outer circumferences of the coil in the direction of the winding axis, and the coil is taken out by separating the winding shaft at the center. Manufacturing method of coil parts. The manufacturing method of the coil components which formed the external shape of the cross section of the said coil in the hexagon shape, the rhombus shape, or the octagon shape.

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