Apparatus and methods for processing exfoliated graphite materials
Methods and apparatus for processing flexible graphite sheet material involve patterning the material, on at least one major surface, prior to further processing of the material such as densification, lamination, folding or shaping into three-dimensional structures. For densification and lamination, the patterning is selected to facilitate the removal of air from the flexible graphite sheet material during the densification and lamination process. For folding or shaping, the patterning is selected to render the graphite sheet material more flexible. In some embodiments, methods for increasing the through-plane conductivity of flexible graphite sheet material are employed. Integrated heat removal devices include sheets of graphite material that have been selectively patterned in different regions to impart desirable localized properties to the material prior to it being shaped or formed into an integrated heat removal device. Coatings and/or resin impregnation can also be used to impart desirable properties to the material or device.
1. An integrated heat removal device comprising a selectively patterned graphite sheet material formed into a three-dimensional structure, wherein said selectively patterned graphite sheet material is patterned on at least one surface with an array of flattened protrusions in a first region of said graphite sheet material to increase a through-plane thermal conductivity of said graphite sheet material in said first region relative to a through-plane thermal conductivity in another region of said graphite sheet material,
wherein said at least one surface is substantially flat in said first region, and a proportion of graphite flakes of said first region that are oriented in a through-plane direction in the first region is greater than a proportion of graphite flakes in another region that are oriented in the through-plane direction in the another region.
2. The integrated heat removal device of claim 1 , wherein said first region comprises a plurality of discrete first regions.
3. The integrated heat removal device of claim 1 , wherein said at least one surface includes two opposing major surfaces, said selectively patterned graphite sheet material is patterned on said two opposing major surfaces with said array of flattened protrusions in said first region of said graphite sheet material.
4. The integrated heat removal device of claim 1 , wherein said selectively patterned graphite sheet material is patterned on at least one of said at least one surface or another surface with a pattern in a second region of said graphite sheet material to increase a surface area of said graphite sheet material in said second region, wherein said pattern is different from said array of flattened protrusions.
5. The integrated heat removal device of claim 1 , wherein said selectively patterned graphite sheet material is patterned on at least one of said at least one surface or another surface with a pattern in a second region of said graphite sheet material to increase a flexibility of said graphite sheet material in said second region, wherein said pattern is different from said array of flattened protrusions.
6. The integrated heat removal device of claim 1 , wherein at least a portion of said integrated heat removal device is impregnated with resin.
7. The integrated heat removal device of claim 1 , wherein at least a portion of said integrated heat removal device is coated with an electrically insulative coating.
8. The integrated heat removal device of claim 7 , wherein said coating comprises poly(p-xylene).
9. The integrated heat removal device of claim 1 , wherein said three-dimensional structure comprises at least one fin.
10. The integrated heat removal device of claim 1 , further comprising an electronic heat generating component mounted upon said first region of said selectively patterned graphite sheet material.
11. A method of making an integrated heat removal device comprising:
(a) selectively patterning a graphite sheet material to form a selectively patterned graphite sheet material; and
(b) forming said selectively patterned graphite sheet material into a three-dimensional structure;
wherein said selectively patterning a graphite sheet material to form a selectively patterned graphite sheet material comprises embossing at least one surface of said graphite sheet material with an array of protrusions in a first region of said graphite sheet material and then compressing said protrusions so that said at least one surface of said graphite sheet material in said first region is substantially flat, to increase a through-plane thermal conductivity of said graphite sheet material relative to a through-plane thermal conductivity in another region of said graphite sheet material.
12. The method of claim 1 , wherein said first region comprises a plurality of discrete first regions.
13. The method of claim 1 , wherein said at least one surface includes two opposing major surfaces, said selectively patterning said at least one surface of said graphite sheet material to form the selectively patterned graphite sheet material comprises embossing the two opposing surfaces of said graphite sheet material with said array of protrusions in said first region of said graphite sheet material.
14. The method of claim 1 , wherein said selectively patterning the graphite sheet material to form the selectively patterned graphite sheet material further comprises patterning at least one of said at least one surface or another surface of said graphite sheet material with a pattern in a second region thereof to increase a surface area of said graphite sheet material in said second region, wherein said pattern is different from said array of protrusions.
15. The method of claim 1 , wherein said selectively patterning the graphite sheet material to form the selectively patterned graphite sheet material further comprises patterning at least one of said at least one surface or another surface of said graphite sheet material with a pattern in a second region thereof to increase the flexibility of said graphite sheet material in said second region, wherein said pattern is different from said array of protrusions.
16. The method of claim 1 , further comprising impregnating at least a portion of said three-dimensional structure with a resin after step (b).
17. The method of claim 1 , further comprising coating at least a portion of said selectively patterned graphite sheet material with an electrically insulative coating.
18. The method of claim 17 , wherein said electrically insulative coating comprises poly(p-xylene).
19. The method of claim 1 , wherein said forming said selectively patterned graphite sheet material into the three-dimensional structure comprises at least one of: folding, corrugating, pleating, bending, and shaping.