Thermally conductive pad with an array of carbon nanotubes and method for making the same

• US 20090053515A1
• Filed: 12/20/2007
• Published: 02/26/2009
• Est. Priority Date: 08/24/2007
• Status: Active Grant

• Current Assignee: Hon Hai Precision Industry Co., Ltd., Tsinghua University
• Original Assignee: Hon Hai Precision Industry Co., Ltd., Tsinghua University
• Inventors: Liu, Chang-Hong, Fan, Shou-Shan, Jiang, Kai-Li, Liu, Liang, Luo, Chun-Xiang
• Granted Patent: US 9,023,477 B2
• Time in Patent Office: Days
• US Class Current: 428/339
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C08J 5/005 Reinforced macromolecular compounds with nanosized materials, e.g. nanoparticles, nanofibres, nanotubes, nanowires, nanorods or nanolayered materials
• CPC Class Codes: C08K 2201/011 Nanostructured additives
• CPC Class Codes: C08K 7/24 inorganic
• CPC Class Codes: C08L 63/00 Compositions of epoxy resins; Compositions of derivatives of epoxy resins
• CPC Class Codes: C08L 83/04 Polysiloxanes
• CPC Class Codes: Y10S 977/742 Carbon nanotubes, CNTs
• CPC Class Codes: Y10T 428/269 including synthetic resin or polymer layer or component
• CPC Class Codes: Y10T 428/30 Self-sustaining carbon mass or layer with impregnant or other layer

Abstract

The present invention relates to a thermally conductive pad and a method for producing the same. The thermally conductive pad includes an array of carbon nanotubes and a polymer matrix. The array of carbon nanotubes has a density in the approximate range from 0.1 g/cm³ to 2.2 g/cm³. The array of carbon nanotubes is incorporated in the polymer matrix by way of polymerization of a pre-polymer of the polymer matrix in situ. Moreover, the method for producing the thermally conductive pad is also included.

Claims

1. A thermally conductive pad comprising:

a polymer matrix; and

an array of carbon nanotubes having a density in the approximate range from 0.1 g/cm³ to 2.2 g/cm³;

the array of carbon nanotubes being incorporated in the polymer matrix by way of polymerization of a pre-polymer of the polymer matrix in situ.

2. The thermally conductive pad as claimed in claim 1, having a thickness in the approximate range from 20 micrometers to 5 millimeters.

3. The thermally conductive pad as claimed in claim 2, wherein the polymer matrix has a first surface and a second surface opposite to the first surface, and the carbon nanotubes being substantially parallel to each other and extending between the first and second surfaces.

4. The thermally conductive pad as claimed in claim 2, wherein each of the carbon nanotubes has a first open end and an opposite second open end.

5. The thermally conductive pad as claimed in claim 3, wherein the carbon nanotubes protrude out from at least one of the first and second surfaces of the polymer matrix.

6. The thermally conductive pad as claimed in claim 1, wherein the carbon nanotubes are densely packed and aligned.

7. The thermally conductive pad as claimed in claim 1, wherein the carbon nanotubes are selected from the group consisting of single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes.

8. The thermally conductive pad as claimed in claim 1, wherein the pre-polymer is selected from the group consisting of silicone rubber, pouring sealant, epoxy resin, and paraffin.

9. A method for producing a thermally conductive pad, the method comprising:

(a) providing a substrate with an array of carbon nanotubes formed thereon;

(b) applying a liquid polymer precursor to the array of carbon nanotubes such that the liquid polymer precursor infuses into the array of carbon nanotubes;

(c) compressing the array of carbon nanotubes in directions parallel to a first axis parallel to a surface of the substrate to form a high-density array of carbon nanotubes with a density in the approximate range from 0.1 g/cm³ to 2.2 g/cm³;

(d) polymerizing the liquid polymer precursor to form a composite material comprising a polymer matrix with the high-density array of carbon nanotubes incorporated therein; and

(e) cutting the composite material in a direction traversing a lengthwise direction of the carbon nanotubes to obtain a thermally conductive pad.

10. The method as claimed in claim 9, further comprising compressing the array of carbon nanotubes in directions parallel to a second axis parallel to the surface of the substrate to form the high-density array of carbon nanotubes, the second axis being perpendicular to the first axis.

11. The method as claimed in claim 9, wherein step (b) comprises the step of dropping the liquid polymer precursor into the array of carbon nanotubes.

12. The method as claimed in claim 9, wherein the array of carbon nanotubes is compressed in a vacuum chamber.

13. The method as claimed in claim 12, wherein a degree of vacuum is less than 0.2 atmospheric pressures.

14. The method as claimed in claim 9, wherein the liquid polymer precursor contains a solidifying agent.

15. The method as claimed in claim 14, wherein the solidifying agent is comprised of epoxy agent, alkaline solidifying agent and acid solidifying agent;

and the alkaline solidifying agent is comprised at least one of aliphatic diamine, aromatic polyamines, modified fatty amines and other nitrogen compounds, and the acidic solidifying agent is comprised at least one of organic acid, acid anhydride, boron trifluoride and complex of them.

16. The method as claimed in claim 9, further comprising a step of solidifying the polymerized polymer precursor at room temperature or at a raised temperature.

17. The method as claimed in claim 9, wherein the surface of the composite material is treated using a process selected from the group consisting of plasma etching, chemical modification, and metal deposition.