Method for making a high current low profile inductor

• US 7,263,761 B1
• Filed: 12/11/2006
• Issued: 09/04/2007
• Est. Priority Date: 07/18/1995
• Status: Expired due to Fees

• Current Assignee: Vishay Dale Electronics (Vishay Intertechnology Incorporated)
• Original Assignee: Vishay Dale Electronics (Vishay Intertechnology Incorporated)
• Inventors: Shafer, Timothy M., Jelkin, Brett W.
• Primary Examiner(s): Nguyen; Tuyen T.
• Application Number:
  US11/609,165
• Publication Number:
  US 20070186407A1
• Time in Patent Office: 267 Days
• Field of Search: 336/65, 336/83, 336/96, 336/192, 336/200, 336/336, 336/233, 29849-585
• US Class Current: 29/602.1
• CPC Class Codes: B29C 43/003 characterised by the choice of material
• CPC Class Codes: B29C 43/18 incorporating preformed parts or layers, e.g. compression moulding around inserts or for coating articles B29C43/206 takes precedence
• CPC Class Codes: B29K 2303/06 Metal powders, metal carbides or the like
• CPC Class Codes: B29K 2995/0008 Magnetic or paramagnetic
• CPC Class Codes: H01F 1/26 by macromolecular organic substances
• CPC Class Codes: H01F 2017/048 with encapsulating core, e.g. made of resin and magnetic powder
• CPC Class Codes: H01F 2027/2861 Coil formed by folding a blank
• 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 27/2847 Sheets; Strips H01F27/2866 takes precedence
• CPC Class Codes: H01F 27/292 Surface mounted devices
• CPC Class Codes: H01F 37/00 Fixed inductances not covered by group H01F17/00
• 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 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor

Abstract

A high current, low profile inductor includes a conductor coil surrounded by magnetic material to form an inductor body. The inductor coil is formed from a flat plate which is cut into a sine-shaped configuration and then is folded in accordion fashion to create a helical coil.

Claims

1. A method for making a high current low profile inductor comprising:

forming an inductor element comprising a coil having and open center and an outside surface, the coil also having first and second coil ends;

making a dry mixture comprising a dry resin and an insulated dry powdered magnetic powder;

compressing the dry mixture around the outside surface of the coil and within the open center of the coil to create an inductor body without liquefying the dry mixture, whereby the inductor body engages the coil both within the coil open center and also the coil outside surface;

the compressing step being done at least at a pressure of 15 tons per square inch.

2. The method according to claim 1 wherein the compressing step is done at from 15 tons per square inch to 25 tons per square inch.

3. The method according to claim 1 wherein a filler and a lubricant are added to the mixture before the compressing step is started.

4. A method for making a high current low profile inductor comprising:

forming an inductor element comprising a coil having and open center and an outside surface, the coil also having first and second coil ends;

insulating a dry magnetic iron powder;

making a dry mixture comprising a dry resin and a dry insulated magnetic iron powder;

compressing the mixture in a single step while the mixture is dry around the outside surface of the coil and within the open center of the coil to create an inductor body, whereby the inductor body engages the coil both within the coil open center and also the coil outside surface.

5. The method of claim 4 wherein the insulating step comprises using phosphoric acid.

6. The method of claim 4 and further comprising wetting the mixture of resin and iron powder and then drying the wetted mixture before the compressing step;

and screening the mixture to a predetermined particle size after the drying step and before the compressing step.

7. The method of claim 6 and further comprising screening the mixture to a particle size of −

50 mesh.

8. A method for making a high current low profile inductor comprising:

forming an inductor element comprising a coil having and open center and an outside surface, the coil also having first and second coil ends;

making a dry mixture comprising a dry resin and an insulated dry powdered magnetic powder;

compressing the dry mixture around the outside surface of the coil and within the open center of the coil to create an inductor body without liquefying the dry mixture, whereby the inductor body engages the coil both within the coil open center and also the coil outside surface;

baking the compressed inductor body, whereby the baked inductor body is self shielding, has a high resistivity exceeding 3 mega ohms, operates up to 1 MHz, and yields a low DC resistance to inductance ratio of two milliohms per micro Henry.