Vertical nanoribbon array (verna) thermal interface materials with enhanced thermal transport properties

Patent metadata

Field	Value
Publication number	US-2018342405-A1
Application number	US-201715602383-A
Country	US
Kind code	A1
Filing date	May 23, 2017
Priority date	May 23, 2017
Publication date	Nov 29, 2018
Grant date	—

Abstract

A thermal interface material (TIM) and method for manufacture is disclosed. A vertically aligned carbon nanotube (VACNT) array is formed on a substrate, then individual CNTs are cleaved to form a vertical nanoribbon array (VERNA). An array of aligned, upright, flat, highly-compliant ribbon elements permit a higher packing density, better ribbon-to-ribbon engagement factor, better contact with adjoining surfaces and potentially achievement of theoretical thermal conductance limit (˜1 GW/m2K) for such nanostructured polycyclic carbon materials. Methods for forming the VERNA include either or both of electrochemical and gas phase processing steps.

First claim

1 . A method of manufacturing a thermal interface material (TIM), comprising the steps of:
growing a vertically aligned carbon nanotube (VACNT) array on a substrate; placing the VACNT array in an electrolyte solution; anodically treating the VACNT to longitudinally cleave the carbon nanotubes (CNTs) into vertical graphene oxide nanoribbons (GONRs); and processing the GONRs to remove oxygen and create an array of vertically aligned graphene nanoribbons (VERNA).

2 . The method of claim 1 , wherein the substrate is an electrically conductive or semiconducting substrate.

3 . The method of claim 2 , wherein the processing step further comprises the steps of:
cathodically polarizing the GONR array to remove oxygen resulting from the step of anodically treating the VACNT; rinsing or exchanging the electrolyte solution with clean water or solvent; and freeze drying or supercritical fluid drying to remove the liquid phase.

4 . The method of claim 3 , further comprising a step of treating the VERNA with temperature of approximately 120 to 350 C to remove any remaining oxygen from the VERNA.

5 . The method of claim 2 , wherein the processing step further comprises the steps of:
rinsing or exchanging the electrolyte solution with clean water or solvent; freeze drying or supercritical fluid drying to remove the liquid phase; and treating the array of GONRs with temperature of approximately 120 to 350 C to remove oxygen.

6 . The method of claim 2 , wherein the processing step further comprises the steps of:
rinsing or exchanging the electrolyte solution with clean water or solvent; freeze drying or supercritical fluid drying to remove the liquid phase; and treating the array of GONRs with a gas phase reducing agent to create the VERNA.

7 . The method of claim 1 , further comprising a second processing step to longitudinally cleave a portion of each graphene nanoribbon (GNR) to create bifurcated GNRs.

8 . The method of claim 1 , wherein the processing step further comprises the steps of:
treating the VACNT with a gas phase reactant to create an array of graphene oxide nanoribbons (GONRs); and treating the array of GONRs with a gas phase reducing agent to create the VERNA.

9 . The method of claim 8 wherein the gas phase reactant is selected from a group including oxygen plasmas, atomic hydrogen and hydrogen plasmas.

10 . The method of claim 8 wherein the gas phase reducing agent is selected from a group including hydrazine vapor, ammonia gas, hydrogen, and gaseous mixtures consisting water vapor, nitrogen and hydrogen.

11 . The method of claim 10 , wherein the step of treating the array of GONRs with a gas phase reducing agent is conducted at temperatures of approximately 300 to 600 C.

12 . The method of claim 8 wherein the treating steps are conducted under ambient pressure conditions.

13 . The method of claim 8 wherein the treating steps are conducted under subambient pressure conditions.

14 . The method of claim 8 wherein the treating steps are conducted in pressurized vessels up to 100 bar.

15 . The method of claim 1 , wherein the processing step further comprises the steps of:
treating the VACNT with gas phase reactant to create an array of graphene oxide nanoribbons (GONRs); and treating the array of GONRs with a temperature of approximately 120 to 350 C to remove oxygen resulting in a VERNA.

16 . The method of claim 1 , wherein the processing step further comprises the steps of:
treating the VACNT with a gas phase reactant to create an array of graphene oxide nanoribbons (GONRs); placing the GONR array in an electrolyte solution; cathodically polarizing the GONR array to remove oxygen; rinsing or exchanging the electrolyte solution with clean water or solvent; and freeze drying or supercritical fluid drying to remove the liquid phase to create the VERNA.

17 . The method of claim 16 , further comprising a step of treating the VERNA with temperature of approximately 120 to 350 C to remove any remaining oxygen from the VERNA.

18 . A thermal interface material (TIM), formed using the method of claim 1 .

19 . A thermal interface material (TIM), formed using the method of claim 3 .

20 . A thermal interface material (TIM), formed using the method of claim 5 .

21 . A thermal interface material (TIM), formed using the method of claim 6 .

22 . A thermal interface material (TIM), formed using the method of claim 8 .

23 . A thermal interface material (TIM), formed using the method of claim 15 .

24 . A thermal interface material (TIM), formed using the method of claim 16 .

25 . A method of manufacturing a thermal interface material (TIM), comprising the steps of:
growing a vertically aligned carbon nanotube (VACNT) array on a substrate; processing the VACNT array to create an array of vertically aligned graphene nanoribbons (VERNA); and processing the VERNA to longitudinally cleave a portion of each graphene nanoribbon (GNR) to create bifurcated GNRs.

Assignees

• Northrop Grumman Systems Corp

Inventors

• Starkovich John A
• Lyon Bradley
• Silverman Edward M

Classifications

• H10W72/01371

  Cleaning, e.g. oxide removal or de-smearing · CPC title

• H10W72/01353

  by etching · CPC title

• H10W72/353

  not comprising solid metals or solid metalloids, e.g. ceramics · CPC title

• H10W40/251

  Organics · CPC title

• H10W40/70

  Fillings or auxiliary members in containers or in encapsulations for thermal protection or control · CPC title