Methods for fabricating current-carrying structures using voltage switchable dielectric materials

• US 8,117,743 B2
• Filed: 11/23/2010
• Issued: 02/21/2012
• Est. Priority Date: 08/27/1999
• Status: Expired due to Fees

• Current Assignee: Littelfuse Incorporated
• Original Assignee: Shocking Technologies, Inc.
• Inventors: Kosowsky, Lex
• Primary Examiner(s): Banks, Derris
• Assistant Examiner(s): PARVEZ, AZM A
• Application Number:
  US12/953,158
• Publication Number:
  US 20110061230A1
• Time in Patent Office: 455 Days
• Field of Search: 298/25, 298/30, 298/31, 298/46, 205/103, 205/104, 205/119, 205/123, 205/125, 205/157, 205/170, 205/222
• US Class Current: 29/846
• CPC Class Codes: H05K 1/0254 High voltage adaptations; Electrical insulation details; Overvoltage or electrostatic discharge protection electrostatic discharge protection for electric apparatus in general H05K9/0067, H05K9/0079; Arrangements for regulating voltages or for using plural voltages
• CPC Class Codes: H05K 1/0373 containing additives, e.g. fillers H05K1/036 takes precedence
• CPC Class Codes: H05K 1/167 incorporating printed resistors
• CPC Class Codes: H05K 2201/0215 Metallic fillers
• CPC Class Codes: H05K 2201/0738 Use of voltage responsive materials, e.g. voltage switchable dielectric or varistor materials
• CPC Class Codes: H05K 2203/105 Using an electrical field; Special methods of applying an electric potential
• CPC Class Codes: H05K 3/188 by direct electroplating
• CPC Class Codes: H05K 3/423 characterised by electroplating method
• CPC Class Codes: H05K 3/426 initial plating of through-holes in substrates without metal
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing
• CPC Class Codes: Y10T 29/49126 Assembling bases
• CPC Class Codes: Y10T 29/49128 Assembling formed circuit to base
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base

Abstract

A method includes providing a voltage switchable dielectric material having a characteristic voltage, exposing the voltage switchable dielectric material to a source of ions associated with an electrically conductive material, and creating a voltage difference between the source and the voltage switchable dielectric material that is greater than the characteristic voltage. Electrical current is allowed to flow from the voltage switchable dielectric material, and the electrically conductive material is deposited on the voltage switchable dielectric material. A body comprises a voltage switchable dielectric material and a conductive material deposited on the voltage switchable dielectric material using an electrochemical process. In some cases, the conductive material is deposited using electroplating.

Claims

1. A method for fabricating a current-carrying formation, the method comprising:

providing a first voltage switchable dielectric (VSD) material having a first characteristic voltage;

exposing the first VSD material to a first source of ions associated with a first electrically conductive material;

creating a first voltage difference between the first source and the first voltage switchable dielectric material, the first voltage difference greater than the first characteristic voltage, and depositing at least a portion of the first electrically conductive material on the first VSD material to form a first current-carrying layer;

exposing the first current-carrying layer to a second source of ions associated with a second electrically conductive material, creating a second voltage difference between the second source and the first current-carrying layer, the second voltage difference greater than the first characteristic voltage; and

depositing at least a portion of the second electrically conductive material on at least a portion of the first current-carrying layer to form a second current-carrying layer.

2. The method of claim 1 wherein the first voltage difference and the second voltage difference are substantially the same.

3. The method of claim 1, further comprising:

providing a second VSD material having a second characteristic voltage;

creating a third voltage differential between the first source and the second VSD material and/or between the second source and the second VSD material, the third voltage differential being greater than the second characteristic voltage; and

depositing at least one of the electrically conductive materials on the second VSD material.

4. The method of claim 1, further comprising:

creating a third voltage differential relative to the second current-carrying layer, the third voltage differential being greater than the first characteristic voltage; and

depositing the first electrically conductive material on at least a portion of the second current-carrying layer.

5. The method of claim 1 wherein the first VSD material is disposed on at least a portion of a substrate.

6. The method of claim 5 wherein the substrate is flexible.

7. The method of claim 5, wherein the substrate includes any of a printed circuit board, printed wiring board, flex circuit, semiconductor wafer, smart card, or RFID tag.

8. The method of claim 1, wherein the first electrically conductive material is deposited in a pin receptacle.

9. The method of claim 1, wherein the first electrically conductive material is deposited in a via.

10. The method of claim 1 wherein depositing includes electroplating.

11. The method of claim 1 wherein depositing includes plasma depositing.

12. The method of claim 1 wherein depositing includes using an electrostatic process.

13. The method of claim 1 wherein depositing includes pulse plating.

14. The method of claim 1 wherein depositing includes reverse pulse plating.

15. The method of claim 1 further comprising polishing the first electrically conductive material.

16. The method of claim 15 wherein polishing includes chemical-mechanical polishing.

17. The method of claim 1 wherein the first electrically conductive material includes a magnetic material.

18. The method of claim 1, wherein providing includes dissolving an electrode that provides the first source of ions.

19. The method of claim 1, wherein the first electrically conductive material includes any of Au, Ag, Cu, Sn, and Al.

20. The method of claim 1, wherein the first electrically conductive material includes Cu.

21. The method of claim 1, wherein the first electrically conductive material includes Au.

22. The method of claim 1, wherein depositing includes depositing on a bottom surface.

23. The method of claim 1, wherein the first characteristic voltage is between 1 and 100 volts.

24. The method of claim 23, wherein the first characteristic voltage is between 5 and 50 volts.

25. The method of claim 1, further comprising masking a portion of the first VSD material such that the masked portion is not exposed to the first source of ions.

26. The method of claim 25, wherein the first electrically conductive material is deposited on an unmasked region of the first VSD material.

27. A method for fabricating a current-carrying formation, the method comprising:

providing a first voltage switchable dielectric (VSD) material having a first characteristic voltage;

exposing the first VSD material to a first source of ions associated with a first electrically conductive material;

creating a first voltage differential between the first source and the first VSD material, the first voltage differential being greater than the first characteristic voltage; and

depositing at least a portion of the first electrically conductive material on the first VSD material to form a current-conducting layer;

wherein the current-carrying layer is disposed on a bottom surface.