Photolithographically-patterned out-of-plane coil structures and method of making

• US 6,392,524 B1
• Filed: 06/09/2000
• Issued: 05/21/2002
• Est. Priority Date: 06/09/2000
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Fork, David K., Chua, Christopher L., Biegelsen, David K.
• Primary Examiner(s): Abrams, Neil
• Application Number:
  US09/591,262
• Time in Patent Office: 711 Days
• Field of Search: 336/200, 336/233, 336/232, 438/381, 296/021
• US Class Current: 336/200
• CPC Class Codes: H01F 17/0006 Printed inductances printed coils for dynamo-electric machines H02K3/26; printed circuits H05K
• CPC Class Codes: H01F 17/0033 with the coil helically wound around a magnetic core
• CPC Class Codes: H01F 17/02 without magnetic core
• CPC Class Codes: H01F 2027/2814 with only part of the coil or of the winding in the printed circuit board, e.g. the remaining coil or winding sections can be made of wires or sheets
• CPC Class Codes: H01F 41/041 Printed circuit coils apparatus or processes for manufacturing printed circuits in general H05K3/00
• CPC Class Codes: H01G 5/18 due to change in inclination, e.g. by flexing, by spiral wrapping
• CPC Class Codes: H01G 5/38 Multiple capacitors, e.g. ganged
• CPC Class Codes: H01L 2224/05568 the whole external layer protruding from the surface
• CPC Class Codes: H01L 2224/05573 Single external layer
• CPC Class Codes: H01L 2224/05624 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/11 Manufacturing methods
• CPC Class Codes: H01L 2224/13155 Nickel [Ni] as principal constituent
• CPC Class Codes: H01L 2224/13171 Chromium [Cr] as principal constituent
• CPC Class Codes: H01L 2224/1318 Molybdenum [Mo] as principal constituent
• CPC Class Codes: H01L 2224/16238 the bump connector connecting to a bonding area protruding from the surface of the item
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/73203 Bump and layer connectors
• CPC Class Codes: H01L 24/11 Manufacturing methods for bumps on insulating substrates H01L21/4853
• CPC Class Codes: H01L 24/13 of an individual bump connector
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01024 : Chromium [Cr]
• CPC Class Codes: H01L 2924/0104 : Zirconium [Zr]
• CPC Class Codes: H01L 2924/01042 : Molybdenum [Mo]
• CPC Class Codes: H01L 2924/013 : Alloys
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/19042 : being an inductor
• CPC Class Codes: H05K 3/4092 : Integral conductive tabs, i.e. conductive parts partly detached from the substrate

Abstract

An out-of-plane micro-structure which can be used for on-chip integration of high-Q inductors and transformers places the magnetic field direction parallel to the substrate plane without requiring high aspect ratio processing. The photolithographically patterned coil structure includes an elastic member having an intrinsic stress profile. The intrinsic stress profile biases a free portion away from the substrate forming a loop winding. An anchor portion remains fixed to the substrate. The free portion end becomes a second anchor portion which may be connected to the substrate via soldering or plating. Alternately, the loop winding can be formed of two elastic members in which the free ends are joined in mid-air. A series of individual coil structures can be joined via their anchor portions to form inductors and transformers.

Claims

1. An out-of-plane coil structure, comprising:

a substrate;

an elastic member comprising a first anchor portion, a loop winding and a second anchor portion, the first anchor portion and the second anchor portion being fixed to the substrate;

wherein the elastic member further comprises a first elastic member comprising a first anchor portion and a first free portion and a second elastic member comprising a second anchor portion and a second free portion;

wherein the first free portion and the second free portion are initially fixed to the substrate, but are released from the substrate to become separated from the substrate, and wherein an intrinsic stress profile in the first elastic member biases the first free portion away from the substrate and wherein an intrinsic stress profile in the second elastic member biases the second free portion away from the substrate; and

wherein the first free portion and the second free portion are connected together forming the loop winding.

2. The coil structure of claim 1, wherein the first anchor portion is fixed to a contact pad on the substrate and the second anchor pad is fixed to a contact pad on the substrate.

3. The coil structure of claim 1, wherein the first free portion is soldered to the second free portion.

4. The coil structure of claim 1, wherein the first free portion and the second free portion are connected together by electroless plating.

5. The coil structure of claim 1, wherein the elastic member is formed of an electrically conductive material.

6. The coil structure of claim 1, further comprising an electrically conductive layer formed on a portion of at least one of an inner surface and an outer surface of the loop winding.

7. The coil structure of claim 1, wherein the second anchor portion is offset tangentially from the first anchor portion.

8. The coil structure of claim 1, further comprising a ferromagnetic core axially disposed within the loop winding.

9. The coil structure of claim 8, wherein the ferromagnetic core comprises ferrite particles disposed in epoxy.

10. The coil structure of claim 8, wherein the ferromagnetic core comprises an electroplated nickel iron permalloy core.

11. An out-of-plane, multi-turn coil structure, comprising:

a substrate; and

a plurality of elastic members, each elastic member comprising a first anchor portion, a loop winding and a second anchor portion, the first anchor portion and the second anchor portion being fixed to the substrate;

wherein the elastic member further comprises a first elastic member comprising a first anchor portion and a first free portion and a second elastic member comprising a second anchor portion and a second free portion;

wherein the first free portion and the second free portion are initially fixed to the substrate, but are released from the substrate to become separated from the substrate, and wherein an intrinsic stress profile in the first elastic member biases the first free portion away from the substrate and wherein an intrinsic stress profile in the second elastic member biases the second free portion away from the substrate; and

wherein the first free portion and the second free portion are connected together forming the loop winding;

wherein the loop windings of the elastic members are disposed axially adjacent to one another and wherein the first anchor portion of one of the plurality of elastic members is connected to the second anchor portion of an adjacent one of the plurality of elastic members.

12. The coil structure of claim 11, wherein each first anchor portion is fixed to a contact pad on the substrate and each second anchor pad is fixed to a contact pad on the substrate.

13. The coil structure of claim 11, wherein each first free portion is soldered to its respective second free portion.

14. The coil structure of claim 11, wherein the first free portion is connected to its respective second free portion by electroless plating.

15. The coil structure of claim 11, wherein each elastic member is formed of an electrically conductive material.

16. The coil structure of claim 11, further comprising, for each elastic member, an electrically conductive layer formed on a portion of at least one of an inner surface and an outer surface of the loop winding.

17. The coil structure of claim 11, wherein for each elastic member, the second anchor portion is offset tangentially from the first anchor portion.

18. The coil structure of claim 11, further comprising a ferromagnetic core axially disposed within the loop windings.

19. The coil structure of claim 18, wherein the ferromagnetic core comprises ferrite particles disposed in epoxy.

20. The coil structure of claim 18, wherein the ferromagnetic core comprises an electroplated nickel iron permalloy core.

21. The coil structure of claim 11, wherein the plurality of elastic members is aligned with an axis which is substantially parallel to the substrate.

22. The coil structure of claim 21, wherein the axis is a straight line.

23. The coil structure of claim 21, wherein the axis is in the shape of a loop, forming a toroidal shaped coil structure.