JP2011243703A - Coil sealed dust core and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coil sealed dust core capable of improving strength of a powder compact around a terminal electrode and preventing cracks and breakage from occurring in the powder compact when performing processing such as bending of the terminal electrode and to provide a method for manufacturing the same.SOLUTION: The coil sealed dust core 1 comprises the powder compact 3 of ferromagnetic metal powder embedding an air-core coil 2, and the terminal electrode 4 with a connection end part 40 connected to the edge parts 2a and 2b of the air-core coil 2 in the powder compact 3, and a terminal part 42 for an external connection which is extended from the connection end part 40 and protruded to the outside of the powder compact 3, where the terminal part 42 of the terminal electrode 4 is bent along the surface of the powder compact 3 and housed in the terminal housing depression 30 formed on the surface of the powder compact 3, and the connection end part 40 of the terminal electrode 4 is placed in a thick part β without the terminal housing depression 30 of the powder compact 3.

Description

  The present invention relates to a coil-embedded dust core used for inductors, transformers, and other electronic devices, and a method for manufacturing the same.

  In recent years, the miniaturization of electric and electronic devices has progressed, and there is a demand for a compact magnetic core that is small (low profile) and can handle a large current. Conventionally, ferrite powder has been used as the material for the dust core, but recently, it requires a large current that has a higher saturation magnetic flux density than that of ferrite powder and maintains DC superposition characteristics up to a high magnetic field. Ferromagnetic metal powders suitable for the intended use are used.

  Patent Document 1 discloses that an air core coil is embedded in a green compact body made of magnetic metal powder, a terminal electrode connected to an edge portion of the air core coil is bent along the outer surface of the powder compact body, and the surface of the powder compact body The structure which accommodates in the terminal accommodation recessed part formed in this is proposed.

JP 2003-309024 A

  In this patent document 1, the terminal electrode which protruded from the compacting body is bent in the position which overlaps with the terminal storage recessed part of a compacting body in a plane. That is, the bent portion of the terminal electrode is located within the width of the terminal housing recess. However, this type of coil-embedded powder magnetic core is required to be downsized (lower profile), and if the terminal electrode is bent at the thin portion of the powder molded body in which the terminal housing recess is formed, the terminal electrode is bent. Since force is sometimes applied to the green compact, cracks are likely to occur in the green compact.

  The present invention improves the strength of a powder molded body around the terminal electrode in a coil-filled powder magnetic core in which the terminal electrode is drawn from the powder molded body, and converts the terminal electrode into a powder molded body during processing such as bending of the terminal electrode. An object of the present invention is to provide a coil-embedded dust core in which cracks and breaks are not generated and a method for manufacturing the same.

  The present invention relates to an air core coil, a powder compact of ferromagnetic metal powder in which the air core coil is embedded, a connection end connected to the edge of the air core coil in the powder compact, and the connection end. A terminal electrode having a terminal portion for external connection that extends from the portion and protrudes outside the powder compacted body, the terminal portion of the terminal electrode being bent along the surface of the powder compacted body, In a coil-embedded dust core that is housed in a terminal housing recess formed on the surface, the powder compact has a thin portion having the terminal housing recess and a thick portion adjacent to the thin portion. The connection end of the terminal electrode is located in the thick part of the green compact.

  It is preferable that the air core coil and the terminal electrode are made of different members and are joined at an edge portion of the air core coil and a connection end portion of the terminal electrode. Alternatively, the air core coil and the terminal electrode are preferably made of the same member.

  According to another aspect of the present invention, there is provided a thin plate-like terminal electrode component having a connection end connected to an edge portion of an air-core coil and a terminal portion for external connection extended from the connection end. Preparing and joining the connection end portion of the terminal electrode component and the edge portion of the air core coil, and the connection end portion of the terminal electrode component and the air core in a state where the terminal portion of the terminal electrode component protrudes A step of embedding a coil in a ferromagnetic metal powder and compressing to form a green compact, and a step of bending a terminal portion protruding from the green compact along the outer surface of the green compact. In the step of forming the green compact, the terminal portion is stored on the surface of the green compact at a position that does not overlap in plan with the position where the terminal portion of the terminal electrode component protrudes. Forming a terminal storage recess That.

  According to the coil-embedded dust core of the present invention and the manufacturing method thereof, since the connection end of the terminal electrode connected to the edge portion of the air-core coil is located in the compacted portion of the dust compact, The strength of the green compact can be improved, and cracks and breaks can be prevented from occurring in the green compact during processing such as bending of the terminal electrode.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view partially showing a first embodiment of a coil-embedded dust core to which the present invention is applied. It is a top view which shows the terminal electrode plate (terminal electrode component) used for manufacture of the coil enclosure powder magnetic core of FIG. It is a figure which expands and shows the terminal electrode shape part of FIG. It is a figure which shows 1 process of the manufacturing method of the coil enclosure powder magnetic core to which this invention is applied. It is a figure which shows the next process of FIG. It is a figure which shows the next process of FIG. It is a perspective view which sees through partially and shows 2nd Embodiment of the coil enclosure type powder magnetic core to which this invention is applied. It is a figure which shows 1 process of the manufacturing method of the coil enclosure powder magnetic core in 2nd Embodiment.

  FIG. 1 shows an embodiment of a coil-embedded dust core to which the present invention is applied. The coil-embedded dust core 1 includes an air-core coil 2, a powder compact 3 made of ferromagnetic metal powder in which the air-core coil 2 is embedded, and a terminal electrode 4 electrically connected to the air-core coil 2. I have.

  The air-core coil 2 is formed by spirally winding a conductive wire coated with an insulating film, and edge portions (a pair of lead ends) drawn in a direction away from the start and end ends located on the upper and lower surfaces of the winding portion 2a. Part) 2b, 2b. The number of turns of the air-core coil 2 can be set as appropriate according to the required inductance.

  The green compact 3 is formed by press-molding magnetic powder made of ferromagnetic metal particles coated with an insulating material, and has a substantially rectangular parallelepiped shape covering the periphery of the air-core coil 2. The green compact 3 includes a terminal storage recess 30 for storing the terminal electrode 4 on a mounting surface (surface of the green compact) 3a used for connection with an external circuit. The terminal storage recess 30 is formed to be exposed on a pair of opposing sides of the mounting surface 3a, that is, the side surfaces 3b and 3c of the green compact 3 so that a part of the terminal electrode 4 can be folded and stored. It has become. The depth of the terminal storage recess 30 is about 0.225 mm, and the height can be reduced by this depth. Fe, Fe-based amorphous alloy, Fe—Ni alloy, Fe—Si alloy or the like can be used as the ferromagnetic metal particles used in the green compact 3, and silicone is used as an insulating material for coating the ferromagnetic metal particles. Resins, epoxy resins, and the like can be used.

  In the green compact 3, the region where the terminal storage recess 30 is formed is a thin portion α where the thickness of the green compact 3 is small, and the region where the terminal storage recess 30 is not formed is the thickness of the green compact 3. Becomes a thick part β.

  The terminal electrode 4 is formed by bending a thin plate-like electrode plate. The terminal electrode 4 protrudes out of the compacting body 3 and the connection end 40 and the claw part 41 embedded in the compacting body 3. Terminal portion 42. The connection end portion 40 and the claw portion 41 extend from both end portions in the width direction of the terminal portion 42 and are separated by an interval corresponding to the width dimension of the terminal portion 42. The width dimension of the terminal portion 42 is equal to or slightly smaller than the width dimension of the terminal housing recess 30. The broken line in FIG. 1 is a fold line.

  The connection end portion 40 is located in the thick portion β of the green compact 3 and the edge portion of the air-core coil 2 drawn to the vicinity of the side surface 3b or 3c of the green compact 3 in the thick portion β. 2b is electrically connected. The joint (connection) between the connection end 40 of the terminal electrode 4 and the edge 2b of the air-core coil 2 can be realized by spot welding, for example.

  The claw portion 41 is positioned at the thick portion β on the opposite side of the thin portion α with respect to the thick portion β where the connection end portion 40 is located, and the terminal electrode 4 is stably provided with respect to the green compact 3. It functions as a holding means for fixing. In the present embodiment, the connection end portion 40 and the claw portion 41 are positioned so as to be arranged symmetrically with respect to the center position of the terminal portion 42. Since the claw portion 41 is inclined by a predetermined angle θ (FIG. 3) with respect to the side surface 3b or 3c of the powder compact 3, it is difficult to come out of the powder compact 3. There is no electrical connection between the claw portion 41 and the air-core coil 2. The claw portion 41 can be omitted if the terminal electrode 4 has sufficient rigidity, or if the terminal portion 42 is fixed to the terminal housing recess 30 of the green compact 3 by means such as adhesion.

  The terminal portion 42 protrudes from the side surface 3b or 3c of the green compact 3 at the thick portion β adjacent to the thin portion α. The terminal portion 42 includes a first bent portion 42a that is bent from the connection end portion 40 and the claw portion 41 toward the side surface 3b or 3c of the green compact 3 and the green compact from the first bent portion 42a. The second bent portion 42b is bent toward the terminal housing recess 30 of the third mounting surface 3a. The electrical connection between the air-core coil 2 in the green compact 3 and the external circuit can be realized through the second bent portion 42b exposed on the mounting surface 3a. That is, the terminal electrode 4 functions as a surface mount terminal.

  Next, with reference to FIGS. 2-6, one Embodiment of the manufacturing method of the coil enclosure powder magnetic core to which this invention is applied is described.

  First, as shown in FIGS. 2 and 3, a thin plate-like terminal electrode plate (terminal electrode component) 45 provided with a large number of terminal electrode shape portions 4 ′ including the connection end portion 40, the claw portion 41 and the terminal portion 42 described above. Prepare. The terminal electrode shape portions 4 ′ are combined in pairs so that the connection end portions 40 and the claw portions 41 face each other with the installation space 45 b of the air-core coil 2 opened, and are connected to the support frame 45 a. . A large number of the pair of terminal electrode shapes 4 ′ are arranged on the terminal electrode plate 45 at a predetermined interval.

  Next, a large number of air-core coils 2 are prepared, and as shown in FIG. 4, the connection end 40 of each terminal electrode shape portion 4 ′ of the terminal electrode plate 45 and the edge portion 2 b of the air-core coil 2 are joined. For joining, for example, spot welding is used. By this joining, a large number of air core coils 2 and the terminal electrode plate 45 are integrated, and the corresponding air core coils 2 and the terminal electrode shape portions 4 ′ are electrically connected.

  Subsequently, magnetic powder made of ferromagnetic metal particles coated with an insulating material is prepared, and the connection end 40, the claw portion 41, and the air-core coil 2 with the terminal portion 42 of each terminal electrode shape portion 4 ′ exposed. Are embedded in the magnetic powder and compressed to form the green compacts 3 respectively. At the time of this compression molding, a molding die composed of a lower punch and an upper punch (not shown) is used, and the terminal receiving recess 30 is formed on the surface that becomes the surface of the green compact body at a position that does not overlap with the protruding position of each terminal portion 42. Form. The lower punch and the upper punch of the molding die are provided with a convex portion having a shape corresponding to the terminal accommodating concave portion to be formed, and if the magnetic powder is compressed through the convex portion, the terminal accommodating concave portion 30 having a desired shape is formed. Can be formed. Thereby, the compacting body 3 by which the terminal accommodation recessed part 30 shown by FIG. 5 was formed in the mounting surface (powder compacting body surface) 3a is obtained.

  In the green compact 3, the thin portion α in which the terminal storage recess 30 is formed does not overlap in plan with the protruding position of the terminal portion 42 of the terminal electrode shape portion 4 ′. That is, the connection end portion 40 and the claw portion 41 of the terminal electrode shape portion 4 ′ are located in the thick portion β where the terminal housing concave portion 30 of the green compact 3 is not formed, and the terminal portion is formed from the thick portion β. 42 protrudes.

  Subsequently, the support frame 45a of the terminal electrode plate is cut off along a cutting line I shown by a broken line in FIG. Thereby, each terminal electrode shape part 4 'is divided | segmented into each terminal electrode 4, and many coil enclosure dust cores which have the air-core coil 2, the compacting body 3, and the terminal electrode 4 are obtained simultaneously.

  Subsequently, as shown in FIG. 6, for each coil-embedded dust core, the terminal portion 42 of the terminal electrode 4 protruding from the thick portion β of the side surface 3b or 3c of the dust compact 3 is connected to the side surface 3b or Bend along 3c. A portion along the side surface 3b or 3c becomes the first bent portion 42a. Further, the first bent portion 42 a is bent along the terminal accommodating recess 30 of the green compact 3. A portion along the terminal housing recess 30 is a second bent portion 42b. Thereby, the coil-embedded dust core 1 of FIG. 1 is obtained.

  7 and 8 show a second embodiment of the coil-embedded dust core to which the present invention is applied. In the second embodiment, the air core coil 2 includes edge portions (a pair of pull-out end portions) 2b and 2b drawn in parallel (in the same pull-out direction) from the start end and the end end of the winding portion 2a. And the first embodiment described above in that the longitudinal direction of the conducting wire of both the edge portions 2b and the longitudinal direction of the connecting end portion 40 of the terminal electrode 4 are electrically connected in a positional relationship intersecting each other by 90 degrees. And different. The configuration other than the drawing direction of both edge portions 2b and the connection portion between both edge portions 2b and connection end portion 40 is the same as that of the first embodiment.

  If the two edge portions 2b of the air-core coil 2 are pulled out in the same direction as described above, the conducting wire can be wound about an extra half circumference as compared with the first embodiment in which both the edge portions 2b are pulled out to be separated from each other. Therefore, it is possible to increase the number of turns by about 0.5T. Further, since both edge portions 2b can be positioned outside the winding portion 2a of the air-core coil 2 (see FIG. 8), the width dimension of the terminal portion 42 of the terminal electrode 4 can be secured wider, and the outside When the present coil-embedded dust core 1 is mounted on the circuit board, the degree of freedom in positional accuracy can be increased. At the same time, the bonding area between the soldering land of the external circuit board and the terminal electrode 4 (especially the second bent portion 42b) can be increased, so that the bonding strength is also improved.

  The coil-embedded dust core according to the second embodiment can be manufactured by the same manufacturing process as that of the first embodiment described above, but a large number of air-core coils 2 are joined to the terminal electrodes 4 of the terminal electrode plate 45, respectively. In doing so, as shown in FIG. 8, both edge portions 2b of the air-core coil 2 drawn out in the same direction intersect with the connection end portions 40 of the terminal electrode shape portions 4 ′ of the terminal electrode plate 45 by 90 degrees. Electrical connection in positional relationship.

  According to each of the above embodiments, since the connection end 40 of the terminal electrode 4 connected to the edge 2b of the air-core coil 2 is positioned at the thick part β of the green compact 3, the connection end 40 The thickness of the green compact 3 around the bent position of the terminal portion 42 (the bent position of the first bent portion 42 a) extended from the green compact 3 and protruding from the green compact 3 can be secured sufficiently. It is possible to prevent cracks and breaks from occurring in the molded body.

  The embodiment has been described above in which the air core coil 2 and the terminal electrode 4 are provided as separate members, and the edge portion 2b of the air core coil 2 and the connection end portion 40 of the terminal electrode 4 are joined. May be composed of the same member.

1 Coil-packed powder magnetic core 2 Air-core coil 3 Powder compact 3a Mounting surface (surface)
3b, 3c Side surface 4 Terminal electrode 4 'Terminal electrode shape part 40 Connection end part 41 Claw part 42 Terminal part 42a 1st bending part 42b 2nd bending part 45 Terminal electrode plate (terminal electrode component)

Claims (4)

An air-core coil, a powder compact of ferromagnetic metal powder in which the air-core coil is embedded, a connection end connected to the edge of the air-core coil in the powder compact, and an extension from the connection end And a terminal electrode having a terminal part for external connection protruding outside the compacted body, and the terminal part of the terminal electrode is bent along the surface of the compacted compact and formed on the surface of the compacted compact. In the coil-filled dust core that is housed in the terminal housing recess,
The green compact has a thin part having the terminal accommodating recess, and a thick part adjacent to the thin part,
The coil-embedded dust core, wherein the connection end portion of the terminal electrode is located in a thick portion of the dust compact. The coil-embedded dust core according to claim 1, wherein the air-core coil and the terminal electrode are made of different members and are joined at an edge portion of the air-core coil and a connection end portion of the terminal electrode. Powder magnetic core. The coil-embedded dust core according to claim 1, wherein the air-core coil and the terminal electrode are made of the same member. A thin plate-like terminal electrode plate having a connection end connected to the edge portion of the air-core coil and an external connection terminal extending from the connection end is prepared. Joining the edge portion of the core coil;
Embedding the connecting end of the terminal electrode plate and the air-core coil in a ferromagnetic metal powder with the terminal portion of the terminal electrode plate protruding, and compressing to form a green compact,
Bending the terminal portion protruding from the green compact along the outer surface of the green compact,
In the step of forming the green compact,
Forming, on the surface of the green compact, a terminal housing recess for housing the terminal portion at a position that does not overlap in plan with the position where the terminal portion of the terminal electrode plate protrudes;
A method for manufacturing a coil-embedded dust core, characterized by: