Method for forming an inductor

• US 6,990,729 B2
• Filed: 09/05/2003
• Issued: 01/31/2006
• Est. Priority Date: 09/05/2003
• Status: Active Grant

• Current Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Pleskach, Michael D., Thomson, Andrew J.
• Primary Examiner(s): Tugbang, A. Dexter
• Assistant Examiner(s): KIM, PAUL D
• Application Number:
  US10/657,054
• Publication Number:
  US 20050052268A1
• Time in Patent Office: 879 Days
• Field of Search: 296/021, 29604-606, 336/176, 336/200, 336/229, 156/89.11, 156/89.12, 156/250
• US Class Current: 29/606
• CPC Class Codes: H01F 17/0033 with the coil helically wound around a magnetic core
• CPC Class Codes: H01F 41/046 structurally combined with ferromagnetic material
• CPC Class Codes: H01L 23/49822 Multilayer substrates multilayer metallisation on monolayer substrate H01L23/498
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/3011 Impedance
• CPC Class Codes: H05K 1/0298 Multilayer circuits
• CPC Class Codes: H05K 1/115 Via connections; Lands around holes or via connections H05K1/112 takes precedence
• CPC Class Codes: H05K 1/165 incorporating printed inductors
• CPC Class Codes: Y10T 156/1052 with cutting, punching, tearing or severing
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor
• CPC Class Codes: Y10T 29/49069 Data storage inductor or core
• CPC Class Codes: Y10T 29/49071 by winding or coiling
• CPC Class Codes: Y10T 29/49073 by assembling coil and core

Abstract

A method for making an embedded toroidal inductor (118) includes forming in a ceramic substrate (100) a first plurality of conductive vias (102) radially spaced a first distance from a central axis (101) so as to define an inner circumference. A second plurality of conductive vias (104) is formed radially spaced a second distance about the central axis so as to define an outer circumference. A first plurality of conductive traces (110) forming an electrical connection between substantially adjacent ones of the first and second plurality of conductive vias is formed on a first surface (106) of the ceramic substrate. Further, a second plurality of conductive traces (110) forming an electrical connection between circumferentially offset ones of the first and second plurality of conductive vias is formed on a second surface of the ceramic substrate opposed from the first surface to define a three dimensional toroidal coil.

Claims

1. A method for forming an inductor, comprising:

forming a ceramic substrate by stacking a plurality of unfired ceramic layers

forming in said ceramic substrate a first plurality of conductive vias radially spaced a first distance from a central axis so as to define an inner circumference;

forming in said ceramic substrate a second plurality of conductive vias radially spaced a second distance about said central axis so as to define an outer circumference;

forming a first plurality of conductive traces disposed in a first plane defined orthogonal to said central axis, said first plurality of conductive traces forming an electrical connection between substantially radially adjacent ones of said first and second plurality of conductive vias;

forming a second plurality of conductive traces disposed in a second plane spaced from said first plane and defined orthogonal to said central axis to define an electrical connection between circumferentially offset ones of said first and second plurality of conductive vias to define a three dimensional toroidal coil;

wherein at least a first one of said ceramic layers has a permeability greater than one over an area that includes said entire substrate, and at least a portion of said first one of said ceramic layers is contained within a toroid shaped core region of said ceramic substrate, defined within said toroidal coil.

2. The method according to claim 1 further comprising the step of firing said ceramic substrate after said conductive vias and said traces have been formed.

3. The method according to claim 1, further comprising the step of selecting at least a second one of said ceramic layers to have a permeability different from said first one of said ceramic layers.

4. The method according to claim 1 wherein said ceramic layers are formed of a low-temperature co-fired ceramic (LTCC) material.

5. The method according to claim 1 further comprising the steps of:

forming a third plurality of conductive vias radially spaced a third distance from said central axis so as to define an second inner circumference, said third distance less than said first distance

forming in said ceramic substrate a fourth plurality of conductive vias radially spaced a fourth distance about said central axis so as to define a second outer circumference, said fourth distance larger than said second distance;

forming a third plurality of conductive traces disposed in a third plane defined orthogonal to said central axis, said third plurality of conductive traces forming an electrical connection between substantially radially adjacent ones of said third and fourth plurality of conductive vias;

forming a fourth plurality of conductive traces disposed in a fourth plane spaced from said first plane and defined orthogonal to said central axis to define an electrical connection between circumferentially offset ones of said third and fourth plurality of conductive vias to define a second three dimensional toroidal coil.

6. The method according to claim 5 further comprising the step of forming an electrical connection between the first and second three-dimensional conductive toroidal coils.

7. The method according to claim 6 further comprising the step of configuring said electrical connection so that the first and second toroidal coils generate a magnetic field in a common direction.

8. A method for forming an inductor, comprising:

forming in a ceramic substrate a first plurality of conductive vias radially spaced a first distance from a central axis so as to define an inner circumference;

forming in said ceramic substrate a second plurality of conductive vias radially spaced a second distance about said central axis so as to define an outer circumference;

forming a first plurality of conductive traces disposed in a first plane defined orthogonal to said central axis, said first plurality of conductive traces forming an electrical connection between substantially radially adjacent ones of said first and second plurality of conductive vias;

forming a second plurality of conductive traces disposed in a second plane spaced from said first plane and defined orthogonal to said central axis to define an electrical connection between circumferentially offset ones of said first and second plurality of conductive vias to define a three dimensional toroidal coil;

forming a third plurality of conductive vias radially spaced a third distance from said central axis so as to define an second inner circumference, said third distance less thin said first distance;

forming in said ceramic substrate a fourth plurality of conductive vias radially spaced a fourth distance about said central axis so as to define a second outer circumference, said fourth distance larger than said second distance;

forming a third plurality of conductive traces disposed in a third plane defined orthogonal to said central axis, said third plurality of conductive traces forming an electrical connection between substantially radially adjacent ones of said third and fourth plurality of conductive vias;

forming a fourth plurality of conductive traces disposed in a fourth plane spaced from said first plane and defined orthogonal to said central axis to define an electrical connection between circumferentially offset ones of said third and fourth plurality of conductive vias to define a second three dimensional toroidal coil.

9. The method according to claim 8 further comprising the step of forming an electrical connection between the first and second three-dimensional conductive toroidal coils.

10. The method according to claim 9 further comprising the step of configuring said electrical connection so that the first and second toroidal coils generate a magnetic field in a common direction.