Coil component and method of manufacturing the same

• US 20040046626A1
• Filed: 06/26/2003
• Published: 03/11/2004
• Est. Priority Date: 02/27/2001
• Status: Active Grant

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Imanishi, Tsunetsugu, Nakata, Toshiyuki, Hamamoto, Hiroyuki, Hiwatashi, Hidetoshi, Kitagawa, Tomokazu
• Granted Patent: US 7,015,783 B2
• Time in Patent Office: Days
• US Class Current: 336/83
• CPC Class Codes: H01F 17/04 with magnetic core
• CPC Class Codes: H01F 17/043 with two, usually identical or nearly identical parts enclosing completely the coil (pot cores)
• 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 27/022 Encapsulation
• 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 27/255 made from particles H01F27/26 takes precedence
• CPC Class Codes: H01F 27/263 Fastening parts of the core together
• CPC Class Codes: H01F 27/2847 Sheets; Strips H01F27/2866 takes precedence
• CPC Class Codes: H01F 27/2852 Construction of conductive connections, of leads
• CPC Class Codes: H01F 27/292 Surface mounted devices
• CPC Class Codes: H01F 3/10 Composite arrangements of magnetic circuits
• CPC Class Codes: H01F 41/005 Impregnating or encapsulating insulating of windings H01F41/12
• 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: Y10T 29/4902 Electromagnet, transformer or inductor

Abstract

A coil component comprising; a coil 2 having a through-hole 1, a magnetic core including the coil, and a terminal 4, wherein magnetic core comprises a top portion 11 disposed at an upper part of the coil, a bottom portion 12 disposed at a lower part of the coil, and a middle portion 13. An outer layer thickness of the middle portion (W1) is less than a diameter of the through-hole, while the top portion and the bottom portion are higher in density than the middle portion. The configuration of the present invention provides a small size coil component with less occurrence of magnetic saturation to prevent lowering of inductance even with thin top portion 11 and bottom portion 12. The coil component further has improved reliability.

Claims

1. A coil component comprising:

a coil having a through-hole;

a magnetic core including said coil; and

a terminal connected to said coil, wherein

said magnetic core includes a top portion disposed at an upper part of said coil, a bottom portion disposed at a lower part of said coil, and a middle portion disposed at the height of said coil, an outer layer thickness of said middle portion is less than a diameter of said through-hole, while said top portion and said bottom portion are higher in density than said middle portion.

2. The coil component of claim 1, wherein said middle portion comprises an inside middle portion positioned in the through-hole and an outside middle portion surrounding an outer part of said coil, said outside middle portion being higher in density than said inside middle portion.

3. The coil component of claim 1, wherein said magnetic core is formed so that a densities of said top portion and said bottom portion are in a range from 5.0 to 6.0 g/cm³ and a density of said inside middle portion is 85% to 98% of the densities of said top portion and said bottom portion.

4. The coil component of claim 1, wherein said coil is an edgewise coil formed by winding a flat wire in such manner that adjacent flat wires are in tight contact with each other.

5. The coil component of claim 1, wherein said magnetic core comprises a binder including thermosetting resin and magnetic powder.

6. The coil component of claim 5, wherein said thermosetting resin is a silicone resin including tough resin component and elastic resin component.

7. The coil component of claim 5, wherein a compressed powder used as a material for manufacturing said magnetic core has a weak portion being unable to keep a shape of said compressed powder and a strong portion being able to keep the shape of said compressed powder, when said compressed powder is re-molded.

8. The coil component of claim 7, wherein a cross section of said compressed powder has E-shape with a back portion, central portion and outside portion.

9. The coil component of claim 8, wherein the back portion of said compressed powder is the strong portion, while the central portion and the outside portion serve as the weak portion.

10. The coil component of claim 7, wherein tip end of the central portion or outside portion of said compressed powder has small peaks and valleys.

11. The coil component of claim 7, wherein at least one dividing groove is provided at the back portion of said compressed powder.

12. A method of manufacturing coil component comprising the steps of:

encapsulating a coil having a through-hole with a magnetic core including magnetic powder; and

forming a terminal connected to said coil, wherein

said encapsulating is processed such that an outer layer thickness of a middle portion including said coil is made less than a diameter of said through-hole, and a top portion of said magnetic core disposed at an upper part of said coil and a bottom portion of said magnetic core disposed at a lower part of said coil are made higher in density than said middle portion.

13. The method of claim 12, wherein said middle portion comprises an inside middle portion disposed in said through-hole and an outside middle portion disposed at an outer periphery of said coil, and a density of said outside middle portion is higher than a density of said inside middle portion.

14. The method of claim 12, wherein densities of said top portion and said bottom portion are in a range from 5.0 to 6.0 g/cm³ and the density of said inside middle portion is from 85% to 98% of the densities of said top portion and said bottom portion.

15. The method of claim 12, wherein said encapsulating process further comprises the steps of:

forming compressed powder with binder including thermosetting resin and magnetic powder; and

forming an encapsulating magnetic core by re-molding said compressed powder under pressure so as to cover said coil.

16. The method of claim 15, wherein said compressed powder is formed through mixing and molding without heating so as not to cure said thermosetting resin, and is re-molded under heat and pressure so that said thermosetting resin cures.

17. The method of claim 15, wherein said forming of compressed powder includes forming of a weak portion and a strong portion, said weak portion being unable to keep a shape of said compressed powder during said re-molding and said strong portion being able to keep a shape of said compressed powder during said re-molding.

18. The method of claim 15, wherein said thermosetting resin comprises silicone resin including tough resin component and elastic resin component.

19. The method of claim 17, wherein said encapsulating magnetic core forming process is executed in such manner that one side of the coil is supported by the strong portion of said compressed powder while the other side of said coil is covered with said weak portion.

20. The method of claim 17, wherein the cross section of said compressed powder has E-shape with a back portion, central portion and outside portion, said back portion being said strong portion, while said central portion and said outside portion being said weak portion.

21. The method of claim 15, wherein tip end of the central portion or outside portion of said compressed powder has small peaks and valleys.

22. The method of claim 15, wherein at least one dividing groove is provided at the back portion of said compressed powder.