Engineering oxide ceramic fillers for thermal interface materials: Enhanced thermal conductivity and thixotropy through hydrophobated MgO/PDMS composite materials

Abstract

Advanced thermal interface materials (TIMs) require high contents of ceramic fillers to exhibit both high isotropic thermal conductivity and suitable rheological viscosity for ensuring low contact thermal resistance. Traditional approaches for achieving this balance often fail and pose ongoing academic and industrial challenges. We develop a novel approach for enhancing both the rheological mobility and thermal conductivity of magnesia (MgO)/polydimethylsiloxane (PDMS) TIMs by employing Ce- and Ti-assisted liquid-phase sintering of MgO fillers (CT-MgO fillers) using a scalable spray-drying method. The liquid-phase sintering of MgO fillers with Ce and Ti additives, which facilitate low-temperature sintering and densification, results in higher thermal conductivity of TIM (8.2 W m−1 K−1 at a filler content of 80 vol.%) compared with commercial alumina filler-based TIMs. Additionally, the hydrophobic surface of CT-MgO fillers enables efficient mixing with PDMS and allows high-loading TIMs (80 vol.%) to maintain a thixotropic state, thereby effectively reducing contact thermal resistance with a copper substrate. This filler-modification strategy, which also provides electrical insulation, is expected to promote the development of high-performance polymer-based TIMs for advanced electronics.