Nanoscale Conformable Thermal Interface Materials with Electronically Enhanced Heat Conduction

Award Information
Agency:
Department of Defense
Branch
Air Force
Amount:
$99,956.00
Award Year:
2010
Program:
STTR
Phase:
Phase I
Contract:
FA9550-10-C-0112
Award Id:
94993
Agency Tracking Number:
F09B-T22-0299
Solicitation Year:
n/a
Solicitation Topic Code:
AF 09TT22
Solicitation Number:
n/a
Small Business Information
1250 Capital of Texas Highway South, Building 3, Suite 400, Austin, TX, 78746
Hubzone Owned:
N
Minority Owned:
N
Woman Owned:
N
Duns:
788622012
Principal Investigator:
Koneru Ramakrishna
Principal Investigator
(512) 680-4169
rama@privatran.com
Business Contact:
Glenn Mortland
President
(512) 633-3476
glenn@privatran.com
Research Institution:
Stanford University
Kenneth E Goodson
Dept. Mechanical Engineering
Bldg. 530, 440 Escondido Mall
Stanford, CA, 94305
(650) 725-2086
Nonprofit college or university
Abstract
Carbon nanotubes (CNTs), single and multi-walled, have very high thermal conductivity and are natural choices to increase teffective thermal conductivity of thermal interface materials (TIMs). However, they have high interfacial thermal resistances of CNT at the base (seed) and at the heat sink end. Broadly, two approaches have been taken to reduce interfacial thermal resistance of CNT on heatsink side. The first method involves increasing the interfacial pressure and the material above (Fischer and co-workers). In the second approach a layer of solder is introduced between CNT and the heat sink. The later approach reduced the interfacial thermal resistance by an order of magnitude. No attempts have been made to reduce the interfacial resistance on the seed side of CNT. In this proposal, a metallic conformal coatings have been proposed. They consist of a flash of Pd, followed by Cu, followed by solder. Such a conformal layer ensures complete, area coverage and is tolerant to variations in manufacturing variable such as statistical variation in CNT heights. On the seed side, it is proposed to etch out the seed followed by polishing/CMP is proposed to eliminate that interface. We propose to investigate indium and a lead-free solder. Attempts will be made to understand the interfaces through modeling. We also propose to simulate thermal performance of a package, to be chosen by Air Force, with proposed changes to TIM. BENEFIT: The proposed conformal coatings can significantly decrease the overall thermal resistance of a TIM with CNT compared to a CNT-solder interface. They can accommodate statistical variations common to CNT manufacturing process. The conformal coatings are compliant and can better withstand cyclic stresses induced due to coefficient of thermal expansion mismatch during temperature cycling. Additionally, we are the first ones to decrease (eliminate) the interfacial stress between CNT and its seed. The impact of significantly decreasing TIM thermal interfacial resistance is beneficial across all product lines where TIMs are used.

* information listed above is at the time of submission.

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