METALLIC INK

• US 20080286488A1
• Filed: 05/15/2008
• Published: 11/20/2008
• Est. Priority Date: 05/18/2007
• Status: Active Grant

• Current Assignee: Applied Nanotech, Inc. (Nano Magic, Inc.)
• Original Assignee: Nano-Proprietary, Inc. (Nano Magic, Inc.)
• Inventors: Yaniv, Zvi, Fink, Richard Lee, Yang, Mohshi, Li, Yunjun, Pavlovsky, Igor, Roundhill, David Max
• Granted Patent: US 10,231,344 B2
• Time in Patent Office: Days
• US Class Current: 427/541
• CPC Class Codes: B22F 1/054 Nanosized particles
• CPC Class Codes: B22F 1/107 containing organic material comprising solvents, e.g. for slip casting
• CPC Class Codes: B22F 1/17 Metallic particles coated with metal
• CPC Class Codes: B22F 2999/00 Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: C22C 47/04 by coating, e.g. with a protective or activated covering
• CPC Class Codes: H01B 1/026 Alloys based on copper
• CPC Class Codes: H05K 1/0393 Flexible materials H05K1/038 takes precedence; specific organic compositions are classified in H05K1/0313 and subgroups
• CPC Class Codes: H05K 2201/0257 Nanoparticles inks comprising nanoparticles H05K1/097
• CPC Class Codes: H05K 2203/0514 Photodevelopable thick film, e.g. conductive or insulating paste
• CPC Class Codes: H05K 2203/107 Using laser light shaping a substrate by laser ablation H05K3/0026
• CPC Class Codes: H05K 2203/1131 Sintering, i.e. fusing of metal particles to achieve or improve electrical conductivity
• CPC Class Codes: H05K 2203/1545 Continuous processing, i.e. involving rolls moving a band-like or solid carrier along a continuous production path
• CPC Class Codes: H05K 3/02 in which the conductive material is applied to the surface of the insulating support and is thereafter removed from such areas of the surface which are not intended for current conducting or shielding

Abstract

Forming a conductive film comprising depositing a non-conductive film on a surface of a substrate, wherein the film contains a plurality of copper nanoparticles and exposing at least a portion of the film to light to make the exposed portion conductive. Exposing of the film to light photosinters or fuses the copper nanoparticles.

Claims

1. A method of forming a conductive film comprising:

depositing a film containing a plurality of copper nanoparticles on a surface of a substrate; and

exposing at least a portion of the film to light to make the exposed portion conductive.

2. The method of claim 1, wherein the exposing at least a portion of the film to light causes at least a portion of the copper nanoparticles to fuse together.

3. The method of claim 1, wherein the exposing at least a portion of the film photosinters at least a portion of the copper nanoparticles.

4. The method of claim 3, wherein the photosintering of copper nanoparticles comprises a first transformation of CuO and Cu₂O to Cu₂O and a second transformation of the Cu₂O to Cu.

5. The method of claim 4, wherein during the photosintering process, the copper oxide migrates away from an area where the nanoparticles are fusing.

6. The method of claim 1, wherein exposing at least a portion of the film comprises directing a laser at the film.

7. The method of claim 1, wherein exposing at least a portion of the film comprises exposing the film to a flash lamp.

8. The method of claim 1, wherein exposing at least a portion of the film comprises exposing the film to a focused beam of light.

9. The method of claim 1, wherein the intensity of the light and a time of exposure is sufficient to make the exposed portion conductive.

10. The method of claim 1, wherein the film exposure occurs in ambient air.

11. The method of claim 1, wherein the film exposure occurs in an inert environment.

12. The method of claim 1, wherein a size of each of the nanoparticles is less than 1000 nm.

13. The method of claim 1, wherein a size of each of the nanoparticles is less than 200 nm.

14. The method of claim 1, wherein the film is deposited from a solution containing copper nanoparticles.

15. The method of claim 14, further comprising adding the nanoparticles to a solvent to form the solution prior to depositing the non-conductive film.

16. The method of claim 15, further comprising adding a dispersing agent to the solution.

17. The method of claim 15, further comprising fragmenting the nanoparticles prior to adding the nanoparticles to the solvent.

18. The method of claim 15, further comprising including an additive in the solution, wherein the additive modifies a viscosity, surface tension, light heat capacity or energy absorbance of the solution.

19. The method of claim 15, further comprising treating the nanoparticles to remove oxides.

20. The method of claim 19, further comprising encapsulating the nanoparticles after the oxides have been removed.

21. The method of claim 1, wherein the film is exposed to the light through a backside of the substrate.

22. The method of claim 3, wherein the substrate is flexible.

23. The method of claim 1, wherein the substrate is a fiber.

33. The method of claim 2, wherein the fusion of the copper nanoparticles is performed in ambient air at room temperature by a photosintering process.

34. The method of claim 33, wherein the photosintering process precludes oxidation of interfaces between the copper nanoparticles.

35. The method of claim 2, wherein the CuO and Cu₂O are reduced during the fusion.

36. The method of claim 35, wherein the CuO is minimized.

37. The method of claim 13, wherein the fused copper nanoparticles have a size ≧

2 nm and ≦

200 nm.

38. The method of claim 1, wherein non-volatile components of the film comprise less than 10% of the total amount.

39. The method of claim 1, wherein the film has a viscosity in a range of 8-20 centipoise, and a surface tension in a range of 20-60 dyne/cm².

40. The method of claim 1, further comprising a repeat of the depositing and exposing steps in order to create multiple layers of the conductive film.

41. The method of claim 35, wherein a concentration of copper oxides in the fused film does not exceed 30%.

42. The method of claim 22, wherein photosintering textures a surface of the flexible substrate.

43. The method of claim 19, wherein the oxides are removed from the nanoparticles using glyoxylic acid.

44. The method of claim 19, wherein the oxides are removed from the nanoparticles using ascorbic acid.

45. The method of claim 19, wherein the oxides are removed from the nanoparticles using ethylenediamine.

46. The method of claim 2, wherein the fused copper nanoparticles have a fused portion between them with a narrower diameter than a diameter of the copper nanoparticles.

47. The method of claim 14, the solution comprising solvents and dispersant agents.

48. The method of claim 47, wherein the solvents are selected from the group consisting of 2-butoxyethyl acetate, Propylene glycol monomethyl ether acetate, Diethylene glycol monoethyl ether acetate, Ethylene glycol butyl ether, 2-Ethoxyethyl acetate, Ethylene Glycol Diacetate, Cyclohexanone, Cyclohexanol, 2-Ethoxyethyl acetate, Ethylene Glycol Diacetate, terpineol, isobutyl alcohol, and isopropyl alcohol.

49. The method of claim 47, wherein the dispersant agents are selected from the group consisting of Triton X-100, Triton X-15, Triton X-45, Triton QS-15, liner alkyl ether, quaternized alkyl imidazoline, polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycol, hexylamine, octylamine, polyethyleneime, amines, and polysiloxanes.

50. The method of claim 47, wherein the dispersant agents are selected from the group consisting of Disperbyk 180, Disperbyk 111, and styrene maleic anhydride copolymer.

51. The method of claim 47, wherein the weight percentage of the dispersant agents varies from 0.5% to 20%.

24. A method of forming a conductive film on a fiber in a roll-to-roll process comprising:

coating the short fibers or chopped fiber with a nanoparticle ink solution;

pre-curing the nanoparticle ink solution on the fiber to form a non-conductive film on the fiber; and

exposing at least a portion of the non-conductive film to light to make the film conductive.

25. The method of claim 24, further comprising dispensing the fiber from a spool.

26. The method of claim 24, wherein coating the fiber comprises immersing the fiber in a nanoparticle ink bath.

27. The method of claim 24, wherein coating the fiber comprises spraying a nanoparticle ink solution onto the fiber.

28. The method of claim 24, wherein pre-curing the nanoparticle ink solution comprises passing the fiber through a drying station to dry the ink.

29. The method of claim 24, wherein exposing at least a portion of the non-conductive film to light comprises passing the fiber to a photosintering station.

30. The method of claim 29, wherein exposing at least a portion of the non-conductive film to light further comprises activating one or more flash lamps in the photosintering station.

31. The method of claim 24, further comprising collecting the exposed fiber in a take-up spool.

32. The method of claim 24, further comprising cutting the exposed fiber into sections.