Polymer-based microfabricated thermal ground plane
Embodiments described herein relate to the concept and designs of a polymer-based thermal ground plane. In accordance with one embodiment, a polymer is utilized as the material to fabricate the thermal ground plane. Other embodiments include am optimized wicking structure design utilizing two arrays of micropillars, use of lithography-based microfabrication of the TGP using copper/polymer processing, micro-posts, throttled releasing holes embedded in the micro-posts, atomic layer deposition (ALD) hydrophilic coating, throttled fluid charging structure and sealing method, defect-free ALD hermetic coating, and compliant structural design.
1. A method for forming a thermal ground plane comprising:
depositing a first sacrificial layer in a first pattern on a first polymer layer;
depositing a second polymer layer on the first sacrificial layer;
depositing a second sacrificial layer on the second polymer layer;
depositing a first masking layer on the second polymer layer having a plurality of exposed regions that expose portions of the second polymer layer;
etching portions of the second polymer layer that are exposed by the first masking layer;
removing the first masking layer;
depositing a sacrificial vapor core layer in a pattern on the second sacrificial layer;
depositing a third polymer layer on the sacrificial vapor core layer;
depositing a second masking layer on the third polymer layer having a plurality of exposed regions that expose portions of the third polymer layer;
etching portions of the third polymer layer that are exposed by the second masking layer;
removing the second masking layer;
removing portions of the sacrificial vapor core layer using the holes in the third polymer layer; and
sealing the holes in the third polymer layer.
2. The method according to claim 1 , further comprising depositing the first polymer layer on a substrate.
3. The method according to claim 1 , wherein after removing portions of the sacrificial vapor core layer the third polymer layer forms a plurality of pillars.
4. The method according to claim 1 , wherein the first pattern comprises a negative of a plurality of pillars.
5. The method according to claim 1 , wherein the second polymer layer comprises a mesh layer.
6. The method according to claim 1 , wherein the masking layer comprises a metal.
7. The method according to claim 1 , wherein the masking layer comprises a plurality of exposed regions.
8. The method according to claim 1 , where the sacrificial vapor core layer may be electroplated on the second polymer layer.
9. The method according to claim 1 , where the vapor core layer form a plurality of pillars.
10. The method according to claim 1 , wherein removing portions of the sacrificial vapor core layer using the holes in the third polymer layer further comprises introducing an introducing an acid through the holes in the third polymer layer.
11. The method according to claim 1 , wherein the sacrificial vapor core layer has a thickness of less than 200 microns.
12. The method according to claim 1 , wherein the second polymer layer has a thickness of less than 50 microns.
13. The method according to claim 1 , wherein the first polymer layer has a thickness of less than 50 microns.
14. The method according to claim 1 , wherein removing portions of the sacrificial vapor core layer using the holes in the third polymer layer further comprises removing portions of the first sacrificial layer.
15. The method according to claim 1 , wherein depositing a third polymer layer on the sacrificial vapor core layer further comprises depositing the third polymer layer into cavities or channels in the sacrificial vapor core layer.