Method for making conductive circuits using powdered metals

• US 7,237,330 B2
• Filed: 09/29/2004
• Issued: 07/03/2007
• Est. Priority Date: 09/10/2001
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Kuhns, David W., Koskenmaki, David C.
• Primary Examiner(s): Trinh; Minh
• Application Number:
  US10/952,673
• Publication Number:
  US 20050039329A1
• Time in Patent Office: 1,007 Days
• Field of Search: 298/25, 29829-834, 29846-852, 298/62, 29600-6021, 343728-729, 343508-509, 343/880, 343/895, 235/441, 361401-402, 361/737, 361/739, 361/752, 361/772, 361/777, 174255-264, 428/209
• US Class Current: 29/825
• CPC Class Codes: H05K 3/102 by bonding of conductive powder, i.e. metallic powder H05K3/12 takes precedence
• 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
• CPC Class Codes: Y10T 428/24273 including aperture
• CPC Class Codes: Y10T 428/24331 including nonapertured component
• CPC Class Codes: Y10T 428/24479 including variation in thickness
• CPC Class Codes: Y10T 428/24917 including metal layer

Abstract

Conductive circuits and methods of making conductive circuits are disclosed.

Claims

1. A method for making an electrically conductive pattern, comprising:

(a) depositing on a substrate a metal powder composition consisting essentially of at least one metal powder, wherein the substrate is selected from the group consisting of (i) paper and (ii) materials that are at least about 10% compressible; and

(b) densifying the composition to form a conductive pattern on the substrate,

wherein percent compressible, represented by X %, means that a substrate dimension measured in a direction parallel to an applied pressure of 30 MPa is [(100−

X)/100]times its dimension in the same direction at an applied pressure of 0.07 MPa and a total volume of the substrate measured at an applied pressure of 30 MPa is [(100−

X)/100]times its volume at an applied pressure of 0.07 MPa.

2. The method of claim 1, further comprising, prior to step (b):

applying a first pressure in a pattern to capture at least a portion of the composition on the substrate.

3. The method of claim 2, further comprising:

removing any uncaptured metal powder composition from the substrate prior to said densifying step.

4. The method of claim 2, wherein said densifying step comprises applying a second pressure, different from the first pressure, to the composition to form the conductive pattern.

5. The method of claim 4, wherein the second pressure is applied substantially equally to (i) portions of the substrate having metal powder composition thereon, and (ii) portions of the substrate without metal powder composition thereon.

6. The method of claim 2, wherein said applying step and said densifying step are performed simultaneously.

7. The method of claim 1, wherein said densifying step (b) comprises applying at least one of pressure, heat, microwave energy and acoustic energy.

8. The method of claim 2, wherein said applying step further comprises application of at least one of heat, microwave energy and acoustic energy.

9. The method of claim 1, further comprising:

removing at least a portion of oxides from surfaces of the metal powder.

10. The method of claim 1, wherein the substrate comprises a material selected from the group consisting of microporous materials, foam materials, nonwoven materials and woven materials.

11. The method of claim 1 wherein the metal powder composition consists essentially of at least one metal powder selected from the group consisting of copper, tin, lead, silver, gold, platinum, graphite, aluminum, nickel, iron, steel and zinc and alloys and combinations thereof.

12. The method of claim 11, wherein the metal powder comprises copper.

13. The method of claim 12, wherein the metal powder further comprises tin.

14. The method of claim 1 wherein the metal powder composition further comprises a liquid.

15. The method of claim 14, wherein the liquid comprises water.

16. The method of claim 1 wherein said densifying step (b) is conducted at a temperature of about 50 to about 300°

C.

17. The method of claim 1, wherein said densifying step (b) is conducted at pressures of about 20 MPa to about 400 MPa.

18. The method of claim 1, wherein the metal powder composition fills at least one via in the substrate and wherein the metal powder provides a conductive path across the via after step (a).

19. The method of claim 1, wherein the substrate comprises a paper.

20. A method for making an electrically conductive pattern, comprising:

(a) depositing on a substrate a metal powder composition comprising at least one metal powder, wherein the substrate is selected from the group consisting of (i) paper and (ii) materials that are at least about 10% compressible;

(b) applying a first pressure in a pattern to capture at least a portion of the composition on at least a portion of the substrate; and

(c) densifying the composition to form a conductive pattern on the substrate, wherein the conductive pattern contains less than 5% by weight of any additives that may have been used during said depositing step.

21. The method of claim 20, wherein the metal powder composition consists essentially of one or more metals.

22. A method for making an electrically conductive pattern, comprising:

(a) depositing on a substrate a metal powder composition comprising at least one metal powder, wherein the substrate is selected from the group consisting of (i) paper and (ii) materials that are at least about 10% compressible;

(b) applying a first pressure in a pattern to capture at least a portion of the composition on at least a portion of the substrate;

(c) removing any uncaptured metal powder from the substrate; and

(d) densifying the composition to form a conductive pattern on the substrate.

23. The method of claim 22, wherein the substrate is paper.