Thermal Interface Materials for Power System Components

ABSTRACT: Improving heat transfer and enhancing mechanical compliance at interfaces has significant impact on military and commercial applications. For example, silicon carbide power electronics operate at much higher temperatures (~250 oC) than their silicon counterparts (<~120 oC) and occupy smaller volumes. Unfortunately, with current thermal management techniques, decreased heat sink volume and air flow available for cooling associated with miniaturization of devices result in thermal management challenges. Mismatch of mechanical properties is also exacerbated by the broader range of component operating temperatures. New, thermal interface materials (TIMs) are needed to prolong the lifetime of high power electronic components, and can be accomplished in two ways: (1) Reducing the device junction temperature given an equivalent thermal management system and (2) accommodation of thermal strains at heterogeneous interfaces to inhibit mechanical failure. Our work plan is designed to develop new materials to address both challenges. We will investigate two different, macroscopic carbon nanotube (CNT) architecutresdouble sided vertically aligned arrays on foil substrates, and planar CNT-based paper materials. The materials will be decorated with nanoparticles designed to reduce acoustic mismatch and promote interfacial heat transfer, as well as enhance elastic recovery of the TIM after expansion and contraction associated with thermal cycling. BENEFIT: The primary benefits are performance improvements derived from enhanced thermal conductance and extreme mechanical compliance that will be stable over multiple thermal cycles. For example, we have developed CNT-based TIMS with<10 mm2 K W-1 at contact pressures of 0.2 MPa, resulting in potentially significant component lifetime (>3x) lifetime improvements. We have also characterized the mechanical response of CNT-based TIMs to cyclic compression, and observed remarkable elastic recovery in the native CNT materials. We believe the nanoparticles will further enhance mechanical compliance.