I-Corps: Thermally Conductive Polymer Based Interface Materials and Substrates

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

As electronic systems continue to shrink and become more energy dense, thermal dissipation is emerging as a roadblock to sustained performance and reliability. One of the main challenges to heat removal is heat transport across interfaces where two surfaces are placed in contact during device packaging. In order to maximize the thermal transport across interfaces, thermally conductive materials are placed between the two surfaces and these materials form the nearly 1 billion dollar market for thermal interface materials (TIMs) (BCC Research). TIMs are found in nearly all forms of electronic devices including consumer products (cell phones, labtops, etc.), power electronics (electric vehicles and power converters for renewable energy applications), and lighting assemblies (including the emerging field of light emitting diodes), to name a few. As the performance and power demands of these devices continues to increase, more heat is being generated and needs to be removed, yet traditional TIMs lack the thermal properties required to enable sufficient heat removal. This team has developed a new technique to fabricate polymers, which traditionally do not conduct heat well, with very high thermal conductivity for use as TIMs. These materials will provide packaging and thermal engineers with a new weapon to combat the electronics heating problem, which will allow for continued innovation across a wide breath of technological systems. The proposed thermal interface materials (TIMs) demonstrate enhanced mechanical compliance and thermal conductivity, resulting in "soft" materials that are exclusively composed of polymer with unprecedented thermal conductivity. Traditionally, "soft" and mechanically compliant materials such as polymers are plagued by low thermal conductivity due to molecular disorder which results in phonon scattering. To overcome low thermal conductivity, high conductivity fillers are often added to improve composite conductivity, but the improvement in thermal conductivity is limited by interfacial phonon scattering and high fill fractions can compromise the materials mechanical properties. This team has found that nanoscale confinement (forcing the polymer into very small pores) can be used to induce alignment of polymer chains, which greatly improves polymer thermal conductivity in the direction of alignment. Using alumina oxide nanoporous templates the team is able to fabricate large area arrays of nanoconfined polymer nanowires with improved thermal conductivity for use as thermal interface materials. The proposed materials are processed through melt or electrochemical methods and can be fabricated using a multitude of polymer systems and architectures, making them suitable for many potential thermal management applications. These materials exhibit thermal conductivities greater than 50x that of bulk polymer and will allow for improved electronics that can maintain low operational temperatures even at increased power densities.