JP2010010426A - Inductor and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly durable inductor, and to provide a method of manufacturing the same. <P>SOLUTION: In the inductor 30a, having a magnetic molding 31 obtained by performing compression molding to magnetic powder 22 containing a thermosetting resin and a powder-like magnetic material, and a coil 21 incorporated in the magnetic molding 31, the magnetic molding 31 includes a recess 35a formed along a center axis 21s of the coil 21. By providing the recess 35a along the center axis 21s, an internal stress by a restoring force of the coil 21 can be relaxed, thus preventing the cracks in the magnetic molding 31, thereby providing the highly durable inductor 30a. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an inductor manufacturing method, and more particularly to an inductor manufacturing method in which a coil and a magnetic body are integrally formed.

  Patent Document 1 includes a coil part having an air core, an exterior part made of a magnetic body including the coil part, and a terminal that is connected to the coil part and protrudes from the exterior part. Combine the binder containing the thermosetting resin and the magnetic powder in a non-heated state where the thermosetting resin is not completely cured and pressurize and mold the two green compacts while breaking the shape of the coil part. It is described that re-press molding so as to coat and heating and molding so that the thermosetting resin is completely cured.

  Patent Document 2 describes a mold used for forming an inductor in which an inductor terminal is coupled to an inductor coil without using a welding method in forming an inductor, and a method for forming an inductor using the mold. The mold is provided with a mold body portion provided with a hollow portion, a mold base portion detachably fixed to the bottom portion of the mold body portion, an insertion hole for inserting a coil, and a pressure receiving pressure inserted and installed in the hollow portion. And a support portion. This mold can provide a wide contact surface between the internal coil of the inductor body and the inductor terminal by integrally molding the inductor body and the inductor terminal.

JP 2002-252120 A JP 2007-13176 A

  An inductor in which a coil and a magnetic body are integrated is being used for various applications as a surface mount device (SMD). Therefore, there is a demand for improvement in performance including further improvement in durability in various use environments.

  In a device having a green compact (magnetic molded body) obtained by pressure molding magnetic powder containing a powdered magnetic body and a thermosetting resin with a built-in coil, typically in an inductor, an air core portion of the coil The inventors of the present application have found that the state of the powder filling the (hollow part) and forming the core coil may affect the performance improvement including the durability. Typically, the occurrence of cracks is observed in the portion filling the air core portion of the coil after pressure molding. This phenomenon is assumed to be due to the repulsive force caused by the coil. Specific factors of the repulsive force are assumed to be the elasticity of the coil itself, the elasticity of the covering material covering the coil wire, and the like.

  One embodiment of the present invention is a device having a magnetic molded body obtained by pressure molding magnetic powder containing a thermosetting resin and a powdered magnetic body, and a coil incorporated in the magnetic molded body, A molded body is a device that includes a recess recessed along the central axis of the coil. A typical device is an inductor.

  By providing the magnetic molding with a dent that is recessed along the central axis of the coil, it is possible to relieve the tensile stress (tension) along the central axis of the coil among the internal stress due to the repulsive force caused by the coil. Therefore, it can suppress that a crack generate | occur | produces in the part (filled part) which filled the air core part of the coil through which the central axis of a coil passes among magnetic moldings. Moreover, since there are few magnetic flux lines (magnetic flux density is small) which passes through the part along the central axis of a coil among magnetic moldings, especially the part of both sides (upper and lower) along a central axis, Providing a recess along the central axis of the coil does not significantly affect the performance as an inductor. Therefore, it is possible to improve the performance including the durability of the device having the magnetic molded body and the coil incorporated therein.

  The magnetic molded body preferably includes a plurality of recesses that are recessed from both sides along the central axis of the coil. The tension along the central axis, which is generated by the repulsive force caused by the coil, can be further relaxed. The dent may penetrate the magnetic molded body.

  Another aspect of the present invention is a method for manufacturing a device having a magnetic molded body obtained by press-molding a magnetic powder containing a thermosetting resin and a powdered magnetic body, and a coil built in the magnetic molded body. It is. This manufacturing method includes a step of pressure-molding the magnetic molded body into a shape including a recess recessed along the central axis of the coil.

  After pressure molding, the repulsive force caused by the coil is released, and even if internal stress occurs in the magnetic molded body, the tension component along the central axis of the coil can be relieved, so the air core part of the coil is filled It can suppress that a crack etc. generate | occur | produce in the part which has done.

  The molding step is typically performed by a press apparatus using a press die. The step of molding includes pressing the magnetic powder with a press plate having a press surface protruding from a portion along the central axis of the coil.

  Further details will be described below with reference to the drawings. Inductors including a magnetic body with a built-in coil are on the market. It was found that when these inductors were cut, many cracks were generated inside.

  FIG. 1 shows one of the possible mechanisms for occurrence of internal cracks. An inductor with a built-in coil is formed as follows using a compression molding method. First, as shown to Fig.1 (a), the coil 21 is set to the metal mold | die 19 for compression molding (mold press), and the magnetic powder 22 which is a to-be-compressed material is filled. A typical mold 19 includes bases (mold bases, cores) 12a and 12b for forming the hollow portion 11 filled with the magnetic powder 22, and a press plate for applying pressure to the magnetic powder 22 in the hollow portion 11. 15a and 15b. In this example, the hollow portion 11 has a cylindrical shape or a square tube shape whose both ends are open, and the press plates 15 a and 15 b arranged above and below the hollow portion 11 serve as a pressing die, and pressure is applied to the magnetic powder 22 from above and below. And press molding the magnetic powder 22.

  A typical coil (inductor coil) 21 is formed by winding a predetermined number of turns of a copper wire or copper body covered with an insulating layer such as polyamideimide. The terminal 21 t of the coil 21 is extended in a direction horizontal or perpendicular to the coil 21. In this example, the terminal 21t of the coil 21 is extended in the horizontal (left-right) direction. The coil 21 can be held at a predetermined position of the hollow portion 11 by inserting or sandwiching the terminal 21t into the mold bases 12a and 12b.

  The magnetic powder 22 is pressure-molded by the mold 19 in a state where the inductor is built in, so that a magnetic molded body is formed. The magnetic powder 22 includes a thermosetting resin and a powdered magnetic material. An example of the magnetic powder is described in JP-A-2006-283190. In JP-A-2006-238190, as an example of a method for producing the magnetic powder 22, the surface of a magnetic conductive metal powder (powdered magnetic material) is coated with a PHPS (perhydropolysilazane) solution, and then an organic system. The binder solution (thermosetting resin) is mixed with an epoxy functional silane or amino functional silane alone or with a coupling agent mixed therewith, and the solution is evaporated to be removed. In this manufacturing method, oxidation is caused when the solution is removed, so that a silica film is formed on the surface of the metal powder, and an insulating magnetic powder (insulating magnetic powder) is formed by the silica film.

  A typical powdery magnetic material (magnetic conductor metal powder) used for the magnetic powder 22 in this embodiment is a dry carbonyl iron powder having an average particle size of 0.5 to 10 μm. A typical organic binder which is a thermosetting resin is a mixed binder of a phenol resin and an epoxy resin. The thermosetting resin may be a urethane resin, a polyimide resin, or a mixture thereof. The powdery magnetic body may be another magnetic body such as an iron-based amorphous alloy. Furthermore, the magnetic powder is a mixture containing a binder containing a thermosetting resin such as a phenol resin, an epoxy resin, a urethane resin, a polyimide resin, or a silicone resin, and a powdered magnetic substance instead of the insulating magnetic powder. (Mixture) may be sufficient.

  As shown in FIG. 1 (b), a pressure (press) of about 0.5 GPa to 2.0 GPa is applied to the magnetic powder 22 filled in the hollow portion 11 of the mold 19 by upper and lower press plates (pressing molds) 15a and 15b. Pressure) F is applied. Further, as shown in FIG. 1C, the upper and lower press plates 15a and 15b are separated, and the magnetic powder 22 is molded into a predetermined shape to form a molded body (a green compact, a magnetic molded body) 25. The product is removed as inductor 90. When this inductor 90 is cut along the plane including the air core portion 21c of the coil 21, a crack (crack) 29 occurs in a portion (center portion) 26 corresponding to the air core portion 21c of the coil 21 of the molded body 25. There is.

  One of the causes of the generation of the crack 29 is a repulsive force caused by the coil 21 generated after pressure molding. Due to this repulsive force, a vertical pulling force (tension, internal stress) acts on the central portion 26 of the molded body 25 filling the air core 21 c of the coil 21. The main factor of the repulsive force resulting from the coil 21 is considered to be the elasticity of the insulating layer covering the copper wire of the coil 21. That is, the insulating layer is compressed and contracted by a press pressure of about 1.0 GPa during pressure molding. Insulating layers such as polyamideimide are often resin-based materials having a relatively large elastic modulus, and when released from the press pressure, the insulating layers tend to return to their original state (thickness). The restoring force (elastic force) becomes an internal stress and acts as a tensile stress on the central portion 26 of the molded body 25.

[First Embodiment]
FIG. 2 shows an outline of the inductor according to the first embodiment of the present invention. The inductor 30a includes a magnetic molded body 31 obtained by pressure-molding the magnetic powder 22, and a coil 21 housed therein. The magnetic molded body 31 is substantially a rectangular parallelepiped as a whole. The upper and lower surfaces 31 a and 31 b of the magnetic molded body 31 are surfaces perpendicular to the central axis 21 s passing through the center of the air core portion 21 c of the built-in coil 21. The contours of these surfaces 31a and 31b are square, and a recess 35a that is recessed from the surrounding surface along the central axis 21s of the coil 21 is provided at the center of the upper and lower surfaces 31a and 31b. The terminal 21 t of the coil 21 built in the magnetic molded body 31 protrudes outward from the side surface 31 c of the magnetic molded body 31. The terminal 21t is bent toward the lower surface 31b.

  FIG. 3 shows a cross section of the inductor 30a. The magnetic molded body 31 includes two recesses 35 a and 35 b that are recessed from both sides along the central axis 21 s of the coil 21. That is, a recess 35 b that is recessed along the central axis 21 s of the coil 21 is also provided at the center of the lower surface 31 b of the magnetic molded body 31. These dents 35a and 35b have a truncated cone shape that narrows toward the center (air core portion) 21c of the coil 21. The recesses 35 a and 35 b are preferably entirely within the range of the air core 21 c of the coil 21, and the maximum diameters of the recesses 35 a and 35 b are preferably narrower than the inner diameter of the coil 21.

  As shown in FIG. 3, when the inductor 30a is press-molded by a press mold 10a described later, an internal stress 41 is generated by a repulsive force caused by the coil 21 particularly after the molding. This internal stress 41 acts as a tensile stress on the central portion 26 of the magnetic molded body 31. As described above, the center portion 26 is a portion that fills the air core portion 21c of the coil 21 and forms a core coil. In this inductor 30a, recesses 35a and 35b are formed above and below the center portion 26. According to simulations by the inventors, the tensile stress 41 applied to the center portion 26 is greater than when the recesses 35a and 35b are not provided. Has been obtained. It is conceivable that these recesses 35a and 35b are deformed in a direction in which the stress applied to the central portion 26 decreases due to the tensile stress 41. Accordingly, the tensile stress 41 applied to the central portion 26 is relaxed, and the generation of cracks in the central portion 26 can be suppressed.

  The central portion 26 of the magnetic molded body 31 is a portion that fills the air core portion 21c of the coil 21 and forms a core coil. However, as indicated by broken lines in FIG. 3, the magnetic flux lines 45 are formed around the coil 21, and the density of the magnetic flux lines passing through the recesses 35 a and 35 b along the central axis 21 s of the coil 21 is low. Therefore, by providing the magnetic molded body 31 with the recesses 35a and 35b along the central axis 21s, it is possible to improve durability without significantly affecting the performance as the inductor 30a, for example, the inductance.

  FIG. 4 shows a step of forming the magnetic molded body 31 by press molding the magnetic powder 22 into a predetermined shape in the manufacturing method of the inductor 30a. The inductor 30a is manufactured by heating and hardening the magnetic molded body 31 after molding the magnetic molded body 31, and bending the coil terminal 21t protruding from the magnetic molded body 31 in the horizontal direction downward for surface mounting. .

  As shown in FIG. 4A, a coil 21 is set in a mold 10a for compression molding (mold press), and a magnetic powder 22 as a material to be compressed is filled. The mold 10a is an open mold similar to the mold 19, and has a base 12a and 12b for forming the rectangular hollow portion 11 filled with the magnetic powder 22, and magnetically moving up and down in the hollow portion 11. Press plates (pressing dies) 16a and 16b for applying pressure to the powder 22 from above and below are provided. The press plates 16a and 16b arranged above and below the hollow portion 11 have substantially flat press surfaces 16s, respectively, except for the protruding portion 16c at the center. The protruding portion 16c protrudes in the shape of a truncated cone in the vertical direction along the central axis 21s of the coil 21 from the flat peripheral portion.

  The coil 21 is fixed at a predetermined position and height of the hollow portion 11 by setting the terminal 21t on the bases 12a and 12b. The magnetic powder 22 is filled on the press surface 16s of the lower press plate 16b inside the hollow portion 11 until a predetermined height (thickness) at which the coil 21 is buried.

  As shown in FIG. 4B, the pressure F1 is applied to the upper and lower press plates 16a and 16b, and the magnetic powder 22 is pressure-molded. The press pressure F1 applied in this step is about 0.5 GPa to 2.0 GPa. Further, as shown in FIG. 4C, the upper and lower press plates 16a and 16b are separated. Thereby, the magnetic powder 22 can be pressure-molded into the magnetic molded body 31 having a shape including the recesses 35a and 35b at the centers of the upper and lower surfaces 31a and 31b. The magnetic molded body 31 incorporates the coil 21, and the recesses 35 a and 35 b are recessed toward the air core portion 21 c of the coil 21 along the central axis 21 s of the coil 21. The inductor 30a is magnetically molded after being taken out of the mold 10a or together with the mold 10a by heating at 120 ° C. to 180 ° C. for 20 minutes to 1 hour, preferably 130 ° C. to 140 ° C. for about 1 hour. The body 31 is cured.

  In the inductor 30a, a magnetic molded body 31 is molded into a shape having recesses 35a and 35b. For this reason, even if a tensile stress is generated inside the magnetic molded body 31 due to the restoring force of the coil 21 when the press pressure is released in FIG. 4C, the tensile stress in the central portion 26 of the magnetic molded body 31 is reduced. Can be relaxed. For this reason, generation | occurrence | production of the crack in the center part 26 of the magnetic molding 31 can be suppressed, and the inductor (device) 30a with which the performance including the durability under use conditions, such as high humidity and high temperature, was improved can be provided.

  It is considered that the tensile stress due to the repulsive force caused by the coil tends to concentrate on the portion of the magnetic molded body 31 along the central axis 21s of the coil 21 and easily causes cracks. Accordingly, by introducing a shape or a surface that can be deformed (microdeformation or microdisplacement) by tensile stress along or near the central axis 21 s of the coil 21 of the magnetic molding 31, The tensile stress in the central portion 26 can be relaxed. As described above, it has been confirmed by the inventors' simulation that the tensile stress when the inductor 30a is removed from the mold 10a is alleviated by introducing the recesses 35a and 35b.

  In this example, recesses 35a and 35b recessed from the periphery are provided on both sides of the coil 21 of the magnetic molded body 31 along the central axis 21s, that is, on the upper and lower surfaces 35a and 35b, respectively. Even if the dent is a device provided with a dent only on one side, that is, one of the surfaces 31a and 31b of the magnetic molded body 31, not on both sides along the central axis 21s, the tensile stress can be reduced. Generation of cracks can be suppressed.

[Second Embodiment]
FIG. 5 shows an outline of the inductor according to the second embodiment of the present invention. The inductor 30b includes a magnetic molded body 32 obtained by pressure-molding the magnetic powder 22, and a coil 21 housed therein. The overall shape of the magnetic molded body 32 is the same as that of the magnetic molded body 31 of the first embodiment. The magnetic molded body 32 of the inductor 30b has a hole 36 penetrating the magnetic molded body 32 along the central axis 21s of the coil 21 at the center of the upper and lower surfaces 32a and 32b. That is, the magnetic molded body 32 of the inductor 30 b includes a recess that is recessed along the central axis 21 s of the coil 21, and the recess 36 is formed as a hole 36 that penetrates the magnetic molded body 32.

  FIG. 6 shows a cross section of the inductor 30b. The hole 36 penetrating the magnetic molded body 32 along the central axis 21 s of the coil 21 has a cylindrical shape, a rectangular tube shape, or a truncated cone shape that narrows toward the center (air core portion) 21 c of the coil 21. It may be a combination. The entire through-hole 36 is preferably within the range of the air core 21 c of the coil 21, and the maximum diameter is preferably narrower than the inner diameter of the coil 21. Furthermore, the diameter of the portion of the through hole 36 that passes through the air core 21c is preferably sufficiently smaller than the inner diameter of the coil 21, for example, about 5 to 50% of the inner diameter, and further 5 to 20% of the inner diameter. It is desirable that the degree.

  The inductor 30 b is provided with a through hole 36 in the magnetic molded body 32 along the central axis 21 s of the coil 21, and the through hole 36 functions as a shape that can be deformed by an internal stress (tensile stress) 41. Therefore, similarly to the inductor 30a of the first embodiment, the internal stress 41 caused by the repulsive force of the coil 21 generated after molding can be relieved. Accordingly, the tensile stress 41 applied to the central portion 26 is relaxed, and the generation of cracks in the central portion 26 can be suppressed. Furthermore, as shown by a broken line in FIG. 6, a through hole 36 is formed along the central axis 21s through which the magnetic flux lines 45 formed around the coil 21 do not pass so much. For this reason, durability can be improved without significantly affecting the performance of the inductor 30b, for example, the inductance.

  FIG. 7 shows a step of forming the magnetic molded body 32 by press-molding the magnetic powder 22 into a predetermined shape in the manufacturing method of the inductor 30b. As shown to Fig.7 (a), the coil 21 is set to the metal mold | die 10b for compression molding (mold press), and the magnetic powder 22 which is a to-be-compressed material is filled. The mold 10b has bases 12a and 12b for forming a rectangular hollow portion 11 filled with the magnetic powder 22, and a pressure for moving the inside of the hollow portion 11 up and down to apply pressure to the magnetic powder 22 from above and below. Press plates (pressing dies) 17a and 17b are provided. The lower press plate 17 b includes a substantially flat press surface 17 s and a rod-shaped portion 17 c that protrudes from the press surface 17 s along the central axis 21 s of the coil 21. The upper press plate 17a includes a substantially flat press surface 17s and a hole 17h into which a rod-shaped portion 17c is inserted.

  The coil 21 is fixed at a predetermined position and height of the hollow portion 11 by setting the terminal 21t on the bases 12a and 12b. The magnetic powder 22 is filled on the press surface 17s of the lower press plate 17b inside the hollow portion 11 until a predetermined height (thickness) at which the coil 21 is buried. The rod-shaped portion 17c protruding from the lower press plate 17b protrudes from the layer of the magnetic powder 22, and the tip of the rod-shaped portion 17c is received in the hole 17h of the upper press plate 17a.

  As shown in FIG. 7B, the pressure F1 is applied to the upper and lower press plates 17a and 17b, and the magnetic powder 22 is pressure-molded. The press pressure F1 applied in this step is about 0.5 GPa to 2.0 GPa. Further, as shown in FIG. 7C, the upper and lower press plates 17a and 17b are separated. Thereby, the magnetic powder 22 can be pressure-molded into the magnetic molded body 32 having a shape including the hole 36 penetrating along the central axis 21 s of the coil 21. The magnetic molded body 32 incorporates the coil 21, and the hole 36 passes through the air core 21 c of the coil 21 along the central axis 21 s of the coil 21. The inductor 30b is magnetically molded after being taken out of the mold 10b or together with the mold 10b by heating at 120 ° C. to 180 ° C. for 20 minutes to 1 hour, preferably at 130 ° C. to 140 ° C. for about 1 hour. The body 32 is cured.

  Also in the inductor 30b, when the press pressure is released in FIG. 7C, a tensile stress is generated inside the magnetic molded body 32 due to the restoring force of the coil 21. However, since the magnetic molded body 32 is provided with the hole 36 penetrating the center up and down, the tensile stress in the central portion 26 of the magnetic molded body 32 can be relieved. For this reason, generation | occurrence | production of the crack in the center part 26 of the magnetic molding 32 can be suppressed, and the inductor (device) 30b in which the performance including the durability in use conditions, such as high humidity and high temperature, was improved can be provided.

[Third Embodiment]
FIG. 8 shows an outline of the inductor according to the third embodiment of the present invention. The inductor 60 is also a surface-mount type device, and has a magnetic solid body 61 that is a rectangular parallelepiped as a whole, and the coil 21 is incorporated (included) in the magnetic molded body 61. Electrodes 75 in which metal powder is pressure-molded are formed at the four corners of one of the upper and lower surfaces 61a and 61b (upper surface in this figure) 61a of the magnetic molded body 61. The terminal 21 t of the built-in coil 21 is connected to two electrodes of these electrodes 75. By mounting the inductor 60 on a printed circuit board (printed wiring board) together with other circuit elements, a device such as a power supply chip can be manufactured. In addition, a circuit including other circuit elements can be formed on one surface of the inductor 60, and a surface-mount type device including a circuit including the inductor can be provided.

  The inductor 60 includes recesses 65a and 65b provided at the centers of the upper and lower surfaces 61a and 61b of the magnetic molded body 61. These recesses 65a and 65b are recesses that are recessed in a substantially truncated cone shape from the surrounding surface along the central axis 21s of the coil 21. Therefore, the cross section of the magnetic molded body 61 is substantially the same as the cross section of the inductor 30a shown in FIG. 3 except for the connection portion of the terminal 21t. Therefore, similarly to the inductor 30a of the first embodiment, the recesses 65a and 65b alleviate the internal stress 41 due to the repulsive force of the coil 21, and can suppress the occurrence of cracks in the central portion. Furthermore, since there is almost no interference between the recesses 65a and 65b and the magnetic flux lines formed around the coil 21, it is possible to improve the durability without significantly affecting the performance of the inductor 60, for example, the inductance.

  FIG. 9 and FIG. 10 show a step of forming a magnetic molded body by pressurizing magnetic powder in the method of manufacturing the inductor 60 according to the third embodiment of the present invention. In this example, the step of forming a magnetic molded body includes a step of temporarily molding magnetic powder into a predetermined shape with a coil built therein, and a layer of a metal powder serving as a surface mounting terminal on the temporarily molded product. Then, a main molding step of integrally molding the inductor is included.

  FIGS. 9A and 9B show a process of temporarily forming the magnetic powder 22 into a predetermined shape. As shown in FIG. 9A, a coil 21 is set in a compression molding (mold press) mold 50a and filled with magnetic powder 22 as a material to be compressed. The mold 50a is an open type, and a base 52 for forming a rectangular hollow portion 51 filled with the magnetic powder 22, and a press for applying pressure to the magnetic powder 22 in the hollow portion 51 from above and below. Plates (pressing dies) 56a and 56b are provided. The press plates 56a and 56b arranged above and below the hollow portion 51 have portions 56c along the central axis 21s of the coil 21 projecting in a truncated cone shape in the vertical direction, respectively, and press surfaces 56s having a flat periphery. Each has.

  A setting hole 56h for inserting the terminal (terminal) 21t of the coil 21 is provided in the lower press plate 56b. The coil 21 is set at a predetermined position and height inside the hollow portion 51 by inserting the terminal 21t into the setting hole 56h of the lower press plate 56b. The magnetic powder 22 is filled on the press surface 56s of the lower press plate 56b inside the hollow portion 51 until a predetermined height (thickness) at which the coil 21 is buried.

  As shown in FIG. 9B, the pressure F11 is applied to the upper and lower press plates 56a and 56b, and the magnetic powder 22 is pressure-molded. The press pressure F11 applied in this temporary molding step is about 0.01 GPa to 0.05 GPa. In the temporary molding step, a product (intermediate body) 64 in which the magnetic powder 22 is temporarily molded into a molded body (green compact) 63 can be formed. The molded body 63 contains (includes) the coil 21. The molded body 63 further has recesses 67a and 67b recessed in a truncated cone shape in the direction of the air core portion 21c along the central axis 21s of the coil 21 at the center of the upper and lower surfaces 63a and 63b. Also in the temporary molding process, internal stress (tensile stress) is generated by the restoring force of the coil 21 when the press pressure is released. In this example, since the dents 67a and 67b are formed along the central axis 21s of the coil 21, the tensile stress applied to the portion (center portion) 63c that fills the air core portion 21c of the coil 21 can be relaxed.

  10A and 10B show the main molding process. In the main molding step, the temporary molded body 63 is further pressurized (main pressure) by the mold 50b. Before the main pressing, the temporary molded body 63 is processed so that a portion (concave portion) on which the metal powder layer is laminated is formed. The mold 50b is obtained by replacing the upper and lower press plates 56a and 56b of the mold 50a with different press plates (pressing molds) 58a and 58b. Each of the press plates 58a and 58b also includes a press surface 58s in which a portion 58c along the central axis 21s of the coil 21 protrudes in a vertical truncated cone shape and the periphery is flat. Therefore, the press plates 58a and 58b can be pressed in a state where the respective press surfaces 58s and the surfaces 63a and 63b of the temporary molded body 63 are in close contact with each other.

  As shown in FIG. 10A, in the molding process, the molded body 63 is inverted, the lower surface 63b from which the terminal 21t of the coil 21 protrudes is the upper surface, and dents are formed by a method such as embossing, machining, and etching. Provide. Next, the metal powder layer 71 is formed by filling the recess with metal powder. A typical metal powder is copper powder. The terminal 21 t of the coil 21 protruding from the temporary molded body 63 is bent and embedded in the metal powder layer 71, and the terminal 21 t is included in the metal powder layer 71. Further, as shown in FIG. 10B, a pressure F <b> 12 of 0.65 GPa to 1.0 GPa is applied to the temporary molded body 63 together with the metal powder layer 71 laminated on the temporary molded body 63. Thereby, the magnetic molding 61 in which the magnetic powder 22 is compressed and solidified is formed. The magnetic molded body 61 is provided with recesses 65a and 65b that are recessed from the upper surface 61a and the lower surface 61b toward the central portion 61c along the central axis 21s of the coil 21. Thereafter, the magnetic molded body 61 is heated at 120 ° C. to 180 ° C. for 20 minutes to 1 hour, preferably at 130 ° C. to 140 ° C. for 1 hour. Thereby, hardening of the magnetic molding 61 is achieved.

  In the inductor 60 as well, when the press pressure is released, tensile stress is generated inside the magnetic molded body 61 due to the restoring force of the coil 21. However, since the magnetic molded body 61 is provided with the recesses 65a and 65b, the tensile stress at the central portion 61c of the magnetic molded body 61 can be relieved. For this reason, generation | occurrence | production of the crack in the center part 61c of the magnetic molding 61 can be suppressed, and the inductor (device) 60 with improved performance including durability under use conditions such as high humidity and high temperature can be provided.

  Also in the third embodiment, similarly to the first embodiment, the magnetic molded body 61 may be molded into a shape in which only one side along the central axis 21 s of the coil 21 is recessed. Moreover, although the case where the metal compression method is used is described in the above manufacturing method, a device including a magnetic molded body having the same shape can be manufactured by a metal powder injection molding method.

It is a figure which shows a mode that a crack generate | occur | produces inside a magnetic molding. It is a perspective view which shows the outline | summary of the inductor of 1st Embodiment. It is sectional drawing which shows the cross section (III-III) of the inductor of 1st Embodiment. It is a figure which shows the manufacturing method of 1st Embodiment. It is a perspective view which shows the outline | summary of the inductor of 2nd Embodiment. It is sectional drawing which shows the cross section (VI-VI) of the inductor of 2nd Embodiment. It is a figure which shows the manufacturing method of 2nd Embodiment. It is a perspective view which shows the outline | summary of the inductor of 3rd Embodiment. It is a figure which shows the process of temporary molding of 3rd Embodiment. It is a figure which shows the process of this shaping | molding of 3rd Embodiment.

Explanation of symbols

  10a, 10b, 19, 50a, 50b ... mold, 11, 51 ... hollow part, 12a, 12b, 52 ... base, 15a, 15b, 16a, 16b, 17a, 17b, 56a, 56b, 58a, 58b ... press plate 16c, 56c, 58c ... protruding part in the center, 16s, 17s, 56s, 58s ... press surface, 21 ... coil, 21t ... end of coil, 21c ... air core part, 21s ... central axis, 22 ... magnetic powder, 25, 31, 32, 61, 63 ... molded body, 26, 61c, 63c ... center portion, 35a, 35b, 65a, 65b, 67a, 67b ... depression, 36 ... through hole, 29 ... crack, 31a, 31b, 32a , 32b, 61a, 61b, 63a, 63b ... the surface of the molded body, 30a, 30b, 60, 90 ... inductor, 71 ... metal powder layer, 76 ... electrode

Claims (6)

A magnetic molded body obtained by pressure-molding a magnetic powder containing a thermosetting resin and a powdered magnetic body;
A device having a coil built in the magnetic molded body,
The magnetic molded body includes a dent recessed along a central axis of the coil.   The device according to claim 1, wherein the magnetic molded body includes a plurality of recesses that are recessed from both sides along a central axis of the coil.   The device according to claim 1, wherein the recess penetrates the magnetic molded body. A method of manufacturing a device having a magnetic molded body obtained by pressure molding a magnetic powder containing a thermosetting resin and a powdered magnetic body, and a coil built in the magnetic molded body,
The manufacturing method including the process of pressure-molding the said magnetic molding to the shape containing the dent dented along the central axis of the said coil. In claim 4,
The step of press molding includes pressing the magnetic powder with a press plate having a press surface protruding from a portion along the central axis of the coil.   6. The manufacturing method according to claim 4, wherein the device is an inductor.

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