Inductor or transformer having a ferromagnetic core that is formed on a printed circuit board

• US 7,005,955 B2
• Filed: 04/23/2003
• Issued: 02/28/2006
• Est. Priority Date: 04/23/2003
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Schumacher, Richard A.
• Primary Examiner(s): Barrera, Ramon M.
• Application Number:
  US10/421,066
• Publication Number:
  US 20040212475A1
• Time in Patent Office: 1,042 Days
• Field of Search: 336/200, 336/234
• US Class Current: 336/200
• CPC Class Codes: H01F 17/0013 with stacked layers
• CPC Class Codes: H01F 17/0033 with the coil helically wound around a magnetic core
• CPC Class Codes: H01F 17/04 with magnetic core
• CPC Class Codes: H01F 27/2804 Printed windings
• CPC Class Codes: H01F 41/046 structurally combined with ferromagnetic material
• CPC Class Codes: H05K 1/165 incorporating printed inductors
• CPC Class Codes: H05K 2201/086 for inductive purposes, e.g. printed inductor with ferrite core
• CPC Class Codes: H05K 2201/09609 Via grid, i.e. two-dimensional array of vias or holes in a single plane interposers H05K2201/10378
• CPC Class Codes: H05K 3/181 by electroless plating adhesives therefor H05K3/387
• CPC Class Codes: H05K 3/244 Finish plating of conductors, especially of copper conductors, e.g. for pads or lands selective plating methods H05K3/243; finish plating of conductors made by printing techniques H05K3/246; solder as finish H05K3/3457, e.g. by plating H05K3/3473
• CPC Class Codes: H05K 3/429 Plated through-holes specially for multilayer circuits, e.g. having connections to inner circuit layers
• CPC Class Codes: H05K 3/4611 by laminating two or more circuit boards H05K3/4652 takes precedence

Abstract

One embodiment of the invention is an inductor that is formed on a printed circuit board comprising a core of ferromagnetic material that is formed on a layer of the printed circuit board, and a winding that surrounds a portion of the core and is formed from a plurality of vias in the printed circuit board.

Claims

1. An inductor that is formed on a printed circuit board comprising:

a core of ferromagnetic material that is formed on a layer of the printed circuit board; and

a winding that surrounds a portion of the core and is formed from a plurality of vias in the printed circuit board;

wherein said core comprises a plurality of layers of ferromagnetic material; and

wherein each layer is separated from an adjacent layer by a layer of dielectric material.

2. The inductor of claim 1, wherein the ferromagnetic material comprises nickel.

3. The inductor of claim 1 further comprising:

another winding that surrounds a portion of the core and is formed from another plurality of vias in the printed circuit board;

wherein the inductor is a transformer.

4. The inductor of claim 1 wherein at least a portion of the printed circuit board that has the inductor is used in an electronic system.

5. The inductor of claim 1, further comprising:

a magnetic shield that is composed of a ferromagnetic material that reduces interference between the inductor and another device.

6. The inductor of claim 1, wherein the inductor is a transformer.

7. A method for forming an inductor on a printed circuit board comprising:

depositing a core of ferromagnetic material onto a portion of the printed circuit board;

forming a plurality of vias around a portion of the core through the printed circuit board;

forming a first connection trace on one side of the printed circuit board; and

forming a second connection trace on another side of the printed circuit board;

wherein the plurality of vias, the first connection trace, and the second connection trace form a coil around a portion of the core;

wherein said core comprises a plurality of layers of ferromagnetic material; and

wherein each layer is separated from an adjacent layer by a layer of dielectric material.

8. The method of claim 7, wherein the method forms a plurality of inductors, the method further comprising:

repeating the depositing a layer of ferromagnetic material, the forming a plurality of vias, the forming a first connection trace, and the forming a second connection trace to form the plurality of inductors on the printed circuit board.

9. The method of claim 8, further comprising:

removing each inductor of the plurality of inductors from the printed circuit board to form a plurality of discreet inductors.

10. The method of claim 7, wherein the ferromagnetic material comprises nickel.

11. The method of claim 7, wherein the inductor is a transformer, the method further comprises:

forming another plurality of vias around a portion of the layer through the printed circuit board;

forming a third connection trace on one side of the printed circuit board; and

forming a fourth connection trace on another side of the printed circuit board;

wherein the another plurality of vias, the third connection trace, and the fourth connection trace form another coil around a portion of the layer.