Printable electrical conductors

• US 20060163744A1
• Filed: 01/13/2006
• Published: 07/27/2006
• Est. Priority Date: 01/14/2005
• Status: Abandoned Application

• Current Assignee: Cabot Corporation
• Original Assignee: Cabot Corporation
• Inventors: Vanheusden, Karel, Kunze, Klaus, Kim, Hyungrak, Hampden-Smith, Mark J., Caruso, James, Kowalski, Mark H., Kodas, Toivo T., James, Anthony R., Stump, Aaron D., Edwards, Chuck, Haubrich, Scott Thomas, Schult, Allen B.
• Application Number:
  US11/331,231
• Publication Number:
  US 20060163744A1
• Time in Patent Office: Days
• US Class Current: 257/773
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C09D 11/101 Inks specially adapted for printing processes involving curing by wave energy or particle radiation, e.g. with UV-curing following the printing
• CPC Class Codes: C09D 11/322 Pigment inks
• CPC Class Codes: C09D 11/36 based on non-aqueous solvents
• CPC Class Codes: C09D 11/52 Electrically conductive inks
• CPC Class Codes: H01L 21/288 from a liquid, e.g. electrolytic deposition
• CPC Class Codes: H01L 2224/8384 Sintering
• CPC Class Codes: H01L 23/49883 the conductive materials containing organic materials or pastes, e.g. for thick films for printed circuits H05K1/092
• CPC Class Codes: H01L 23/5328 containing conductive organic materials or pastes, e.g. conductive adhesives, inks
• CPC Class Codes: H01L 24/27 Manufacturing methods
• CPC Class Codes: H01L 24/29 of an individual layer connector
• 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 2924/12044 OLED
• CPC Class Codes: H05K 1/095 for polymer thick films, i.e. having a permanent organic polymeric binder
• CPC Class Codes: H05K 1/097 Inks comprising nanoparticles and specially adapted for being sintered at low temperature H05K1/095 takes precedence
• CPC Class Codes: H05K 2201/0116 Porous, e.g. foam
• CPC Class Codes: H05K 2203/1131 Sintering, i.e. fusing of metal particles to achieve or improve electrical conductivity
• CPC Class Codes: H05K 3/12 using thick film techniques, e.g. printing techniques to apply the conductive material or similar techniques for applying conductive paste or ink patterns
• CPC Class Codes: H05K 3/125 : by ink-jet printing
• CPC Class Codes: H05K 3/1283 : After-treatment of the printed patterns, e.g. sintering or curing methods
• CPC Class Codes: H10K 71/611 : using printing deposition, e.g. ink jet printing

Abstract

An electrical conductor formed from one or more metallic inks. The electrical conductor comprises a network of interconnected metallic nodes. Each node comprises a metallic composition, e.g., one or more metals or alloys. The network defines a plurality of pores having an average pore volume of less than about 10,000,000 nm³. The electrical conductors advantageously have a high degree of conductivity, e.g., a resistivity of not greater than about 10× the resistivity of the (bulk) metallic composition, which forms the individual nodes.

Claims

1. An electrical conductor, comprising a network of interconnected metallic nodes, the nodes comprising a metallic composition, the network defining a plurality of pores having an average pore volume of less than about 10,000,000 nm³, and the electrical conductor having a resistivity of not greater than about 10×

the resistivity of the bulk metallic composition.

2. The electrical conductor of claim 1, wherein the network comprises fused interconnected metallic nodes.

3. The electrical conductor of claim 2, wherein the metallic composition comprises a metal selected from the group consisting of silver, gold, copper, nickel, cobalt, palladium, platinum, indium, tin, zinc, titanium, chromium, tantalum, tungsten, iron, rhodium, iridium, ruthenium, osmium, aluminum and lead.

4. The electrical conductor of claim 2, wherein the metallic composition comprises an alloy comprising at least two metals, each of the two metals being selected from the group consisting of silver, gold, copper, nickel, cobalt, palladium, platinum, indium, tin, zinc, titanium, chromium, tantalum, tungsten, iron, rhodium, iridium, ruthenium, osmium, aluminum and lead.

5. The electrical conductor of claim 4, wherein the alloy comprises a combination of metals selected from the group consisting of silver/nickel, silver/copper, silver/cobalt, platinum/copper, platinum/ruthenium, platinum/iridium, platinum/gold, palladium/gold, palladium/silver, nickel/copper, nickel/chromium, and titanium/palladium/gold.

6. The electrical conductor of claim 4, wherein the alloy comprises at least three metals.

7. The electrical conductor of claim 2, wherein the resistivity is not greater than 5×

the resistivity of the metallic composition.

8. The electrical conductor of claim 2, wherein at least a portion of the pores are at least partially filled with a composition selected from the group consisting of carbon, alumina, silica, and glass.

9. The electrical conductor of claim 2, wherein at least a portion of the pores are at least partially filled with an organic material.

10. The electrical conductor of claim 9, wherein the organic material comprises an organic polymer.

11. The electrical conductor of claim 10, wherein the polymer comprises units of a monomer, which comprises at least one heteroatom selected from O and N.

12. The electrical conductor of claim 10, wherein the polymer comprises units of a monomer which comprises one or more of a hydroxyl group, a carbonyl group, an ether group, an amido group, a carboxyl group, an imido group and an amino group.

13. The electrical conductor of claim 10, wherein the polymer comprises units of at least one monomer which comprises a structural element selected from —

COO—

, —

O—

CO—

O—

, —

C—

O—

C—

, —

CO—

O—

CO—

, —

CONR—

, —

NR—

CO—

O—

, —

NR¹—

CO—

NR²—

, —

CO—

NR—

CO—

, —

SO₂—

NR— and

—

SO₂—

O—

, wherein R, R¹ and R² independently represent hydrogen or an organic radical.

14. The electrical conductor of claim 10, wherein the polymer comprises a polymer of vinylpyrrolidone.

15. The electrical conductor of claim 14, wherein the polymer of vinylpyrrolidone comprises a homopolymer.

16. The electrical conductor of claim 14, wherein the polymer of vinylpyrrolidone comprises a copolymer.

17. The electrical conductor of claim 16, wherein the copolymer is selected from the group consisting of a copolymer of vinylpyrrolidone and vinylacetate;

a copolymer of vinylpyrrolidone and vinylimidazole;

a copolymer of vinylpyrrolidone and styrene;

a copolymer of vinylpyrrolidone and 2-dimethylaminoethyl methacrylate; and

a copolymer of vinylpyrrolidone and vinylcaprolactam.

18. The electrical conductor of claim 2, wherein the average pore volume is less than about 1,000,000 nm³.

19. The electrical conductor of claim 18, wherein the average pore volume is less than about 100,000 nm³.

20. The electrical conductor of claim 2, wherein the average distance between adjacent pores is from about 1 nm to about 500 nm.

21. The electrical conductor of claim 2, wherein the electrical conductor comprises the pores in an amount less than about 50 volume percent, based on the total volume of the electrical conductor.

22. The electrical conductor of claim 21, wherein the pores comprise less than about 25 volume percent of the electrical conductor, based on the total volume of the electrical conductor.

23. The electrical conductor of claim 2, wherein the pores have an ordered arrangement within the electrical conductor.

24. The electrical conductor of claim 2, wherein the pores have a random arrangement within the electrical conductor.

25. The electrical conductor of claim 2, formed by a process comprising the steps of:

(a) providing an ink comprising metallic nanoparticles and a liquid vehicle;

(b) depositing the ink on a substrate; and

(c) removing a majority of the liquid vehicle from the deposited ink to form the nodes and the pores in the electrical conductor.

26. The electrical conductor of claim 25, wherein step (c) comprises:

heating the deposited ink under conditions effective to remove the majority of the liquid vehicle, and sinter adjacent metallic nanoparticles to one another to form the nodes and the pores of the electrical conductor.

27. The electrical conductor of claim 26, wherein step (c) comprises heating the ink on the substrate to a maximum temperature of less than about 200°

C.

28. The electrical conductor of claim 26, wherein the maximum temperature is less than about 100°

C.

29. The electrical conductor of claim 26, wherein the ink further comprises a composition selected from the group consisting of alumina, silica, glass, and carbon, the composition filling at least a portion of the pores in step (c).

30. The electrical conductor of claim 26, wherein the ink further comprises an organic material, which fills at least a portion of the pores in step (c).

31. The electrical conductor of claim 30, wherein the organic material comprises a composition selected from the group consisting of remaining ink solvents, carbon and an organic polymer.

32. The electrical conductor of claim 31, wherein the polymer comprises units of a monomer, which comprises at least one heteroatom selected from O and N.

33. The electrical conductor of claim 31, wherein the polymer comprises units of a monomer which comprises one or more of a hydroxyl group, a carbonyl group, an ether group, an amido group, a carboxyl group, an imido group and an amino group.

34. The electrical conductor of claim 31, wherein the polymer comprises units of at least one monomer which comprises a structural element selected from —

COO—

, —

O—

CO—

O—

, —

C—

O—

C—

, —

CO—

O—

CO—

, —

CONR—

, —

NR—

CO—

O—

, —

NR¹—

CO—

NR²—

, —

CO—

NR—

CO—

, —

SO₂—

NR— and

—

SO₂—

O—

, wherein R, R¹ and R² independently represent hydrogen or an organic radical.

35. The electrical conductor of claim 31, wherein the polymer comprises a polymer of vinyl pyrrolidone.

36. The electrical conductor of claim 35, wherein the polymer of vinyl pyrrolidone comprises a homopolymer.

37. An electrical conductor, comprising a plurality of touching metallic nanoparticles, wherein the nanoparticles are tightly packed and form a plurality of voids, wherein at least about 95 percent of the nanoparticles, by number, are not sintered to any adjacent nanoparticles, the electrical conductor having a resistivity of not greater than about 20×

the resistivity of the bulk metallic composition.

38. The electrical conductor of claim 37, wherein the metallic nanoparticles comprise a metal selected from the group consisting of silver, gold, copper, nickel, cobalt, palladium, platinum, indium, tin, zinc, titanium, chromium, tantalum, tungsten, iron, rhodium, iridium, ruthenium, osmium, aluminum and lead.

39. The electrical conductor of claim 37, wherein the metallic nanoparticles comprise an alloy comprising at least two metals, each of the two metals being selected from the group consisting of silver, gold, copper, nickel, cobalt, palladium, platinum, indium, tin, zinc, titanium, chromium, tantalum, tungsten, iron, rhodium, iridium, ruthenium, osmium, aluminum and lead.

40. The electrical conductor of claim 39, wherein the alloy comprises a combination of metals selected from the group consisting of silver/nickel, silver/copper, silver/cobalt, platinum/copper, platinum/ruthenium, platinum/iridium, platinum/gold, palladium/gold, palladium/silver, nickel/copper, nickel/chromium, and titanium/palladium/gold.

41. The electrical conductor of claim 39, wherein the alloy comprises at least three metals.

42. The electrical conductor of claim 37, wherein the resistivity is not greater than 10×

the resistivity of the metallic composition.

43. The electrical conductor of claim 42, wherein the resistivity is not greater than 5×

the resistivity of the metallic composition.

44. The electrical conductor of claim 37, wherein at least a portion of the voids are at least partially filled with a composition selected from the group consisting of carbon, alumina, silica, and glass.

45. The electrical conductor of claim 37, wherein at least a portion of the voids are at least partially filled with an organic material.

46. The electrical conductor of claim 45, wherein the organic material fills at least 70 volume percent of the voids.

47. The electrical conductor of claim 46, wherein the organic material fills at least 90 volume percent of the voids.

48. The electrical conductor of claim 47, wherein the organic material fills at least 95 volume percent of the voids.

49. The electrical conductor of claim 45, wherein the organic material comprises an organic polymer.

50. The electrical conductor of claim 45, wherein the polymer comprises units of a monomer, which comprises at least one heteroatom selected from O and N.

51. The electrical conductor of claim 45, wherein the polymer comprises units of a monomer which comprises one or more of a hydroxyl group, a carbonyl group, an ether group, an amido group, a carboxyl group, an imido group and an amino group.

52. The electrical conductor of claim 45, wherein the polymer comprises units of at least one monomer which comprises a structural element selected from —

COO—

, —

O—

CO—

O—

, —

C—

O—

C—

, —

CO—

O—

CO—

, —

CONR—

, —

NR—

CO—

O—

, —

NR¹—

CO—

NR²—

, —

CO—

NR—

CO—

, —

SO₂—

NR— and

—

SO₂—

O—

, wherein R, R¹ and R² independently represent hydrogen or an organic radical.

53. The electrical conductor of claim 45, wherein the polymer comprises a polymer of vinylpyrrolidone.

54. The electrical conductor of claim 53, wherein the polymer of vinylpyrrolidone comprises a homopolymer.

55. The electrical conductor of claim 53, wherein the polymer of vinylpyrrolidone comprises a copolymer.

56. The electrical conductor of claim 55, wherein the copolymer is selected from the group consisting of a copolymer of vinylpyrrolidone and vinylacetate;

a copolymer of vinylpyrrolidone and vinylimidazole;

a copolymer of vinylpyrrolidone and styrene;

a copolymer of vinylpyrrolidone and 2-dimethylaminoethyl methacrylate; and

a copolymer of vinylpyrrolidone and vinylcaprolactam.

57. The electrical conductor of claim 37, wherein the plurality of voids has an average void volume of less than about 10,000,000 nm³.

58. The electrical conductor of claim 57, wherein the average void volume is less than about 1,000,000 nm³.

59. The electrical conductor of claim 58, wherein the average void volume is less than about 100,000 nm³.