Coil-embedded dust core and method for manufacturing the same

• US 6,791,445 B2
• Filed: 02/19/2002
• Issued: 09/14/2004
• Est. Priority Date: 02/21/2001
• Status: Active Grant

• Current Assignee: TDK Corporation
• Original Assignee: TDK Corporation
• Inventors: Chou, Tsutomu, Suzuki, Tsuneo, Shibata, Kazuhiko, Moro, Hideharu, Kitajima, Yasuhiko, Nagasaka, Takashi, Tamura, Junetsu
• Primary Examiner(s): Mai, Anh
• Application Number:
  US10/078,947
• Publication Number:
  US 20020158739A1
• Time in Patent Office: 938 Days
• Field of Search: 336/90, 336/92, 336/96, 336/160, 336/192, 336/83, 336/198, 336/200, 336/223, 336/232
• US Class Current: 336/90
• CPC Class Codes: H01F 17/04 with magnetic core
• CPC Class Codes: H01F 2017/046 helical coil made of flat wire, e.g. with smaller extension of wire cross section in the direction of the longitudinal axis
• CPC Class Codes: H01F 27/027 specially adapted for combination of signal type inductors or transformers with electronic circuits, e.g. mounting on printed circuit boards
• CPC Class Codes: H01F 41/0246 Manufacturing of magnetic circuits by moulding or by pressing powder magnetic cores made by moulding or by pressing powder H01F27/255; soft magnetic particles H01F1/20, H01F1/36
• CPC Class Codes: H01F 41/127 Encapsulating or impregnating encapsulating coil and core H01F41/005
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor
• CPC Class Codes: Y10T 29/49071 by winding or coiling

Abstract

A coil-embedded dust core and a method for manufacturing the coil-embedded dust core are provided. The coil-embedded dust core comprises a coil formed from a flat conductor wound in a coil configuration, and a green body consisting of insulating material-coated ferromagnetic metal particles. This results in a coil-embedded dust core more compact in size but with larger inductance. A rectangular wire can be used as the flat conductor. In addition, parts of the coil may function as terminal sections. In this case, the terminal sections of the coil may be formed wider than other part of the coil. The coil-embedded dust core is less prone to joint failures between a coil and terminal sections and to insulation failures of the coil and the terminal section with respect to the magnetic powder. The coil-embedded dust core is more compact while achieving larger inductance.

Claims

1. A coil-embedded dust core, comprising:

a green body formed from ferromagnetic metal particles coated with an insulating material; and

a coil embedded inside the green body, the coil being formed from a flat, insulation-coated conductor wound in a coil.

2. A coil-embedded dust core according to claim 1, wherein the coil is formed from a rectangular wire wound in a coil.

3. A coil-embedded dust core according to claim 1 or claim 2, wherein the coil has parts that function as terminal sections.

4. A coil-embedded dust core according to claim 1, wherein the flat conductor includes a end section having two opposed surface that are exposed outside the green body.

5. A coil-embedded dust core according to claim 3, wherein the terminal sections are wider than other parts of the coil.

6. A coil-embedded dust core according to claim 2, wherein lead-out end sections of the rectangular wire are formed into wide terminal sections by a flattening process.

7. A coil-embedded dust core according to claim 1, wherein the green body has front and back surfaces that oppose each other across a predetermined space and side surfaces formed around the front and back surfaces, and an end section of the coil extends outside the green body along one of the side surfaces.

8. A coil-embedded dust core according to claim 1, wherein the rectangular wire has flat parallel surfaces defining a width of the rectangular wire and side surfaces defining a height of the rectangular wire on both sides of the flat parallel surfaces, the flat parallel surfaces being wider than the side surfaces, wherein the rectangular wire is wound in a coil in edgewise winding to form layers of windings in the coil such that the flat parallel surfaces of the windings are substantially stacked on top of the other.

9. A coil-embedded dust core according to claim 8, wherein the coil defines an outer circumference side and an inner circumference side of the flat parallel surfaces, and a thickness of the flat conductor on the outer circumference side is smaller than a thickness thereof on the inner circumference side.

10. A coil-embedded dust core, comprising:

a dust core section molded with magnetic powder formed from ferromagnetic metal particles coated with an insulating material and a coil embedded inside the magnetic powder; and

terminal sections outside the dust core section,

wherein the coil and the terminal sections are not connected to one another.

11. A coil-embedded dust core comprising:

a green body formed from ferromagnetic metal particles coated with an insulating material; and

a coil embedded inside the green body, the coil being formed from a flat, insulation-coated conductor, the flat conductor being wound in edgewise winding in the coil such that the flat conductors are stacked on top of one another with substantially no spacing between adjacent flat conductors.