High-Precision Thermal Characterization of Ultra-Low Thermal Resistance Copper Nano-Wire-Polydimethylsiloxane Composite Thermal Interface Materials Tape

Abstract Thermal interface materials (TIMs) play a crucial role in thermal management in modern electronics, where minimizing overall thermal resistance is critical for reliable and efficient operation. Among various advanced TIMs, composites such as copper nanowires embedded in polydimethylsiloxane (CuNWs/PDMS) show great promise due to their high thermal conductivity and high mechanical compliance. However, thermal characterizations in previous studies have often been limited by poor thermal contact at the interfaces between TIMs and adjacent substrates, which introduces significant measurement uncertainties. In this work, we present a high-precision thermal characterization technique using infrared (IR) cross-sectional microscopy for CuNWs/PDMS composite TIMs. To overcome the limitations of dry contact resistance, we apply thin layers of a gallium-based liquid metal (LM) at the interfaces, which significantly reduce the interfacial thermal resistance from ∼10−4 to 1.4 × 10−6 m2K/W. When used with a 1 mm-thick silicon reference wafer, this configuration achieves an effective thermal resistance of (3.23±0.6) × 10−6 m2K/W for the CuNWs/PDMS composite. Theoretical analyses suggest the potential for achieving even lower thermal resistance values with optimized LM wetting thickness.