Formulations for voltage switchable dielectric materials having a stepped voltage response and methods for making the same

• US 8,163,595 B2
• Filed: 11/23/2010
• Issued: 04/24/2012
• Est. Priority Date: 09/24/2006
• Status: Expired due to Fees

• Current Assignee: Littelfuse Incorporated
• Original Assignee: Shocking Technologies, Inc.
• Inventors: Kosowsky, Lex, Fleming, Robert
• Primary Examiner(s): HO, TU TU V
• Application Number:
  US12/953,309
• Publication Number:
  US 20110062388A1
• Time in Patent Office: 518 Days
• Field of Search: 438/99, 438/478, 438/900, 257/3, 257/40, 257/183, 257/E45.001, 252/500
• US Class Current: 438/99
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: H01C 7/12 Overvoltage protection resistors series resistors structurally associated with spark gaps H01T1/16
• CPC Class Codes: H01L 21/02112 characterised by the material of the layer
• CPC Class Codes: H01L 21/02118 carbon based polymeric organic or inorganic material, e.g. polyimides, poly cyclobutene or PVC polymers per se C08G, photoresist per se G03F
• CPC Class Codes: H01L 21/02126 the material containing Si, O, and at least one of H, N, C, F, or other non-metal elements, e.g. SiOC, SiOC:H or SiONC
• CPC Class Codes: H01L 21/02167 the material being a silicon carbide not containing oxygen, e.g. SiC, SiC:H or silicon carbonitrides H01L21/02126 and H01L21/0214 take precedence
• CPC Class Codes: H01L 21/02175 characterised by the metal H01L21/02197 takes precedence
• CPC Class Codes: H01L 21/312 Organic layers, e.g. photoresist H01L21/3105, H01L21/32 take precedence; photoresists per se G03C
• CPC Class Codes: H01L 21/3148 Silicon Carbide layers
• CPC Class Codes: H01L 21/318 composed of nitrides
• CPC Class Codes: Y10S 438/90 Bulk effect device making

Abstract

Formulations for voltage switchable dielectric materials include two or more different types of semiconductive materials uniformly dispersed within a dielectric matrix material. The semiconductive materials are selected to have different bandgap energies in order to provide the voltage switchable dielectric material with a stepped voltage response. The semiconductive materials may comprise inorganic particles, organic particles, or an organic material that is soluble in, or miscible with, the dielectric matrix material. Formulations optionally can also include electrically conductive materials. At least one of the conductive or semiconductive materials in a formulation can comprise particles characterized by an aspect ratio of at least 3 or greater.

Claims

1. A method for fabricating a voltage switchable dielectric material comprising:

adding first, second, and third semiconductive materials to a resin, each of the first, second, and third semiconductive materials being characterized by a different bandgap energy;

mixing the resin until the first, second, and third semiconductive materials are uniformly dispersed in the resin; and

curing the resin, wherein curing includes exposing the resin to a plurality of curing periods, wherein at least one of the curing periods is at a higher temperature than the immediately preceding curing period.

2. The method of claim 1 wherein mixing includes sonication.

3. The method of claim 1 wherein mixing is performed with a rotor-stator mixer.

4. The method of claim 1 further comprising adding a solvent to the resin during mixing.

5. The method of claim 1 wherein the solvent comprises N-methyl-2 pyrrolidone.

6. The method of claim 1 further comprising adding a conductive material to the resin before mixing the resin.

7. The method of claim 1 wherein at least one of the first, second, or third semiconductive materials comprises a solvent soluble organic material.

8. A method for fabricating a voltage switchable dielectric material comprising:

adding first, second, and third semiconductive materials to a resin, each of the first, second, and third semiconductive materials being characterized by a different bandgap energy;

mixing the resin until the first, second, and third semiconductive materials are uniformly dispersed in the resin, and adding a solvent to the resin during mixing; and

curing the resin.

9. The method of claim 8 wherein mixing includes sonication.

10. The method of claim 8 wherein mixing is performed with a rotor-stator mixer.

11. The method of claim 8 wherein curing the resin includes exposing the resin to a plurality of curing periods, wherein at least one of the curing periods is at a higher temperature than the immediately preceding curing period.

12. The method of claim 8 wherein the solvent comprises N-methyl-2 pyrrolidone.

13. The method of claim 8 further comprising adding a conductive material to the resin before mixing the resin.

14. The method of claim 8 wherein at least one of the first, second, or third semiconductive materials comprises a solvent soluble organic material.

15. A method for fabricating a voltage switchable dielectric material comprising:

adding first, second, and third semiconductive materials to a resin, each of the first, second, and third semiconductive materials being characterized by a different bandgap energy, wherein at least one of the first, second, or third semiconductive materials comprises a solvent soluble organic material;

mixing the resin until the first, second, and third semiconductive materials are uniformly dispersed in the resin; and

curing the resin.

16. The method of claim 15, wherein the soluble organic semiconductor material is at least one of carbon, carbon nanotubes, and carbon fullerenes.

17. The method of claim 15, wherein the soluble organic semiconductor material is a covalently bonded chemical group or moiety of a nanotube.

18. The method of claim 15, wherein the soluble organic semiconductor material is at least one of poly-3-hexylthiophene, polythiophene, polyacteylene, poly(3,4-ethylenedioxythiophene), poly(styrenesulfonate), pentacene, (8-hydroxyquinolinolato) aluminum (III), or N,N′

-di-[(naphthalenyl)-N,N′

diphenyl]-1,1′

-biphenyl-4,4′

-diamine (NPD).

19. The method of claim 15, wherein the soluble organic semiconductor material is derived from at least one of a monomer, oligomer, or polymer of thiophene, analine, phenylene, vinylene, fluorene, naphthalene, pyrrole, acetylene, carbazole, pyrrolidone, cyano materials, anthracene, pentacene, rubrene, perylene, or oxadizole.

20. The method of claim 15, wherein the soluble organic semiconductor material is a photo-active organic material.

21. The method of claim 15, wherein the soluble organic semiconductor material is polythiophene.

22. The method of claim 15 wherein mixing includes sonication.

23. The method of claim 15 wherein mixing is performed with a rotor-stator mixer.

24. The method of claim 15 wherein curing includes exposing the resin to a plurality of curing periods, wherein at least one of the curing periods is at a higher temperature than the immediately preceding curing period.

25. The method of claim 15 further comprising adding a solvent to the resin during the mixing process.

26. The method of claim 15 wherein the solvent comprises N-methyl-2 pyrrolidone.

27. The method of claim 15 further comprising adding a conductive material to the resin before mixing the resin.

28. An electronic device comprising a voltage switchable dielectric (VSD) material, the VSD material comprising:

a resin;

a first, a second, and a third semiconductive material, each of the first, second, and third semiconductive materials being characterized by a different bandgap energy;

wherein

at least one of the first, second, or third semiconductive materials comprises a solvent soluble organic material;

the first, second, and third semiconductive materials are dispersed in the resin; and

the VSD material is cured.

29. The electronic device of claim 28, wherein the electronic device is at least one of a printed circuit board, a semiconductor package, a radio frequency identification (RFID) tag, a light emitting diode (LED), a display backplane, or a discrete surge suppressing device.

30. The electronic device of claim 28, wherein the soluble organic semiconductor material is at least one of carbon, carbon nanotubes, and carbon fullerenes.

31. The electronic device of claim 28, wherein the soluble organic semiconductor material is a covalently bonded chemical group or moiety of a nanotube.

32. The electronic device of claim 28, wherein the soluble organic semiconductor material is at least one of poly-3-hexylthiophene, polythiophene, polyacteylene, poly(3,4-ethylenedioxythiophene), poly(styrenesulfonate), pentacene, (8-hydroxyquinolinolato) aluminum (III), or N,N′

-di-[(naphthalenyl)-N,N′

diphenyl]-1,1′

-biphenyl-4,4′

-diamine (NPD).

33. The electronic device of claim 28, wherein the soluble organic semiconductor material is derived from at least one of a monomer, oligomer, or polymer of thiophene, analine, phenylene, vinylene, fluorene, naphthalene, pyrrole, acetylene, carbazole, pyrrolidone, cyano materials, anthracene, pentacene, rubrene, perylene, or oxadizole.

34. The electronic device of claim 28, wherein the soluble organic semiconductor material is a photo-active organic material.

35. The electronic device of claim 28, wherein the soluble organic semiconductor material is polythiophene.