Flexible graphite sheet support structure and thermal management arrangement

• US 10,177,070 B2
• Filed: 12/02/2015
• Issued: 01/08/2019
• Est. Priority Date: 12/10/2014
• Status: Active Grant

• Current Assignee: NeoGraf Solutions, LLC
• Original Assignee: NeoGraf Solutions, LLC
• Inventors: Dornauer, Frank P., Kramer, Greg P., Smalc, Martin D.
• Primary Examiner(s): Williams, Alexander Oscar
• Application Number:
  US15/529,644
• Publication Number:
  US 20170365538A1
• Time in Patent Office: 1,133 Days
• Field of Search: 257713, 257718, 257706, 361 78, 361720, 361709, 361710, 361704, 361705, 361708, 361711, 361719, 165 803, 16510433, 165185
• CPC Class Codes: C01B 32/20 Graphite
• CPC Class Codes: F28F 21/02 of carbon, e.g. graphite
• CPC Class Codes: F28F 2255/02 Flexible elements
• CPC Class Codes: H01L 23/3672 Foil-like cooling fins or heat sinks being part of lead-frames H01L23/49568
• CPC Class Codes: H01L 23/373 Cooling facilitated by selection of materials for the device or materials for thermal expansion adaptation, e.g. carbon
• CPC Class Codes: H01L 23/3738 Semiconductor materials
• 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 33/641 characterized by the materials
• CPC Class Codes: H01L 33/642 characterized by the shape
• CPC Class Codes: H05K 7/20481 characterised by the material composition exhibiting specific thermal properties

Abstract

A flexible graphite sheet support structure forms a thermal management arrangement for device having a heat source. The flexible graphite sheet support structure includes first and second spaced apart support members and a flexible graphite sheet secured to the spaced apart support members forming a free standing flex accommodating section that spans between them. Curve retention members having convex curved surfaces are used to keep the flex accommodating section in a bell shaped curve while preventing the flexible graphite sheet from exceeding a minimum bend radius. The thermal management arrangement formed by the flexible graphite sheet support structure enables the flexible graphite sheet to move heat from one support structure to the other while reducing the transmission of vibration between them and allowing relative movement between the spaced apart support structures.

Claims

1. A flexible graphite sheet support structure comprising:

a first support member and a second support member spaced apart from the first support member, wherein one of the first and second support members is adapted for movement relative to the other;

a flexible graphite sheet secured to the first and second spaced apart support members and having a free standing flex accommodating section extending between the first and second spaced apart members, wherein the flex accommodating section is bell curve-shaped having a central curved portion disposed between and adjacent to oppositely disposed outwardly facing concave curved portions such that the free standing flex accommodating section is not secured to other structures; and

a first curve retention member disposed adjacent to the first support member, the first curve retention member having a convex curved surface disposed adjacent and facing a respective one of the outwardly facing concave curved portions, and a second curve retention member disposed adjacent to the second support member, the second curve retention member having a convex curved surface disposed adjacent and facing the other one of the outwardly facing concave curved portions, wherein the flexible graphite sheet is not secured to the convex curved surfaces.

2. The flexible graphite sheet support structure of claim 1 wherein the flexible graphite sheet has a thickness from between about 0.025 mm to about 0.500 mm and a density from between about 0.6 g/cc to about 2.0 g/cc.

3. The flexible graphite sheet support structure of claim 1 wherein the outwardly facing concave curved portions of the flexible graphite sheet have respective radii R₂ and R₃ and the central curved portion has a radius R₁, and further comprising at least one of:

a. R₁≠

R₂ and R₁≠

R₃;

b. R₁=R₂=R₃;

c. R₂≠

R₃;

d. R₂ and R₃ are constant over the convex curved surfaces;

e. R₂ and R₃ are equal over the convex curved surfaces; and

f. R₂ and R₃ vary along the convex curved surfaces such that the convex curved surfaces define surfaces which are at least one of non-circular curves, Euler spirals, spiral curves and cubic curves.

4. The flexible graphite sheet support structure of claim 1 wherein the outwardly facing concave curved portions of the flexible graphite sheet have respective radii R₂ and R₃ and the central curved portion has a radius R₁, and wherein the support members are spaced apart by distance D_G and wherein R₁+R₁+R₂+R₃=D_G and R₁=R₂=R₃.

5. The flexible graphite sheet support structure of claim 1 wherein the flexible graphite sheet further comprises at least one portion which includes a plurality of graphite sheets laminated together and at least one portion which includes the plurality of graphite sheets as separate graphite sheets not laminated together.

6. The flexible graphite sheet support structure of claim 1 wherein the flexible graphite sheet comprises at least one of one or more sheets of compressed particles of exfoliated graphite and one or more sheets of pyrolytic graphite.

20. The flexible graphite sheet support structure of claim 1 wherein a first one of the concave curved portions is disposed adjacent the first support member and a second one of the concave curved portions is disposed adjacent the second support member.

21. The flexible graphite sheet support structure of claim 1 wherein the flexible graphite sheet consists of one or more sheets of compressed particles of exfoliated graphite.

22. The flexible graphite sheet support structure of claim 1 wherein the flexible graphite sheet consists of one or more sheets of pyrolytic graphite.

23. The flexible graphite sheet support structure of claim 1 wherein the first curve retention member is formed integrally with the first support member and the second curve retention member is formed integrally with the second support member.

7. A thermal management arrangement comprising:

a first support member;

a second support member spaced apart from the first support member; and

a flexible graphite sheet secured to the first and second support members for transferring heat across a span between the first and second spaced apart support members, the flexible graphite sheet having a free standing curve-shaped flex accommodating section extending between the spaced apart support members, wherein the flex accommodating section has a central curved portion disposed between and adjacent to oppositely disposed outwardly facing concave curved portions such that a first one of the concave curved portions is disposed adjacent the first support member and a second one of the concave curved portions is disposed adjacent the second support member, and wherein the free standing flex accommodating section is not secured to other structures.

8. The thermal management arrangement according to claim 7 further comprising at least one heat generating electronic component in thermal contact with the flexible graphite sheet.

9. The thermal management arrangement of claim 7 further comprising:

a first curve retention member disposed adjacent to the first support member, the first curve retention member having a convex curved surface disposed adjacent and facing a respective one of the outwardly facing concave curved portions for maintaining predetermined bend radius in the flexible graphite; and

a second curve retention member disposed adjacent to the second support member, the second curve retention member having a convex curved surface disposed adjacent and facing the other one of the outwardly facing concave curved portions for maintaining predetermined bend radius in the flexible graphite.

10. The thermal management arrangement according to claim 7 wherein the flexible graphite sheet comprises at least one of one or more sheets of compressed particles of exfoliated graphite and one or more sheets of pyrolytic graphite.

11. The thermal management arrangement according to claim 7 wherein the flexible graphite sheet has an in-plane thermal conductivity of at least 150/m*K.

12. The thermal management arrangement according to claim 7 wherein the flexible graphite sheet has a thickness from between about 0.025 mm to about 0.500 mm and a density from between about 0.6 g/cc to about 2.0 g/cc.

13. The thermal management arrangement according to claim 9 wherein the flexible graphite sheet is not secured to the convex curved surfaces of the curve retention members.

14. The thermal management arrangement according to claim 7 wherein the flexible graphite sheet includes a plurality of flexible graphite sheets as separate graphite sheets not laminated together.

15. The thermal management arrangement according to claim 7 wherein the flexible graphite sheet includes at least one portion which includes a plurality of graphite sheets laminated together and at least one portion which includes the plurality of graphite sheets as separate graphite sheets not laminated together.

24. The thermal management arrangement of claim 7 wherein the flexible graphite sheet consists of one or more sheets of compressed particles of exfoliated graphite.

25. The thermal management arrangement of claim 7 wherein the flexible graphite sheet consists of one or more sheets of pyrolytic graphite.

26. The thermal management arrangement of claim 7 wherein the first curve retention member is formed integrally with the first support member and the second curve retention member is formed integrally with the second support member.

16. A method of forming a thermal management arrangement comprising:

providing first and second spaced apart support members forming a span between the spaced apart support members;

securing a flexible graphite sheet to the first and second spaced apart support members forming a free standing curve-shaped flex accommodating section extending between the first and second spaced apart members, wherein the flex accommodating section has a central curved portion disposed between and adjacent to oppositely disposed outwardly facing concave curved portions such that a first one of the concave curved portions is disposed adjacent the first support member and a second one of the concave curved portions is disposed adjacent the second support member, and wherein the free standing flex accommodating section is not secured to other structures;

generating heat with a heat source in thermal contact with flexible graphite sheet; and

transferring the heat across the span using the flexible graphite sheet.

17. The method of claim 16 further comprising moving one of the first and second support members relative to the other of the first and second support members.

18. The method of claim 16 wherein the flexible graphite sheet includes a plurality of separate graphite sheets.

19. The method of claim 16 wherein the flex accommodating portion includes a plurality of graphite sheets as separate graphite sheets not laminated together.

27. The method of claim 16 wherein the flexible graphite sheet consists of one or more sheets of compressed particles of exfoliated graphite.

28. The method of claim 16 wherein the flexible graphite sheet consists of one or more sheets of pyrolytic graphite.

29. The method of claim 16 wherein the flexible graphite sheet comprises one or more sheets of pyrolytic graphite and one or more sheets of compressed particles of exfoliated graphite.