Simultaneous Reduction of Bulk and Contact Thermal Resistance in High‐Loading Thermal Interface Materials Using Self‐Assembled Monolayers

Abstract Thermal interface materials (TIMs) play a pivotal role in the transfer of heat from high‐temperature sources, such as CPUs, to heat sinks in power electronics. The effectiveness of grease‐type TIMs is determined by their effective thermal impedance (R_EFF), which hinges on optimizing both the specific bulk (R_B) and contact (R_C) thermal resistances. Achieving concurrent optimization of these resistances poses a significant challenge, especially in high filler loading TIMs, typically above 76 vol%. This research leverages interface engineering through Self‐Assembled Monolayers (SAMs) to address this challenge. A substantial decrease in R_EFF is realized to 0.169 K cm² W⁻¹, a tenfold enhancement compared to non‐SAM treated TIMs, which exhibit R_EFF values of 2.265 K cm² W⁻¹. This leap in performance is primarily ascribed to the reduced surface energy of SAM treated Al₂O₃, leading to lower particle‐to‐particle Van der Waals forces, thereby improving particle dispersion and strengthening interfacial bonds. Furthermore, longer carbon chains in SAMs result in increased R_B, yet a decrease in R_C, due to the chains' capacity for enhanced energy absorption and molecular entanglement. The investigation underscores the significance of shorter‐chain SAMs in fine‐tuning thermal resistance, highlighting the crucial role of molecular architecture in the design of advanced TIMs.