High-Precision Thermal Characterization of Ultra-Low Thermal Resistance Copper Nano-Wire (CuNWs)-Polydimethylsiloxane (PDMS) Composite Thermal Interface Materials (TIMs) Tape

Abstract This work details high-precision thermal characterization of CuNWs-PDMS composite TIMs using infrared (IR) cross-sectional microscopy. To enhance measurement sensitivity and to reduce the thermal resistances across TIM tester components and sample, we apply thin layers of high thermal conductivity gallium-based liquid metal (LM) to reduce the dry contact thermal interface resistances from ∼10−4 to 1.4 × 10−6 m2KW−1. Application of the LM in combination with a 1 mm thick silicon wafer as the reference layer, yields thermal resistance of ∼(3.23 ± 0.6) × 10−6 m2KW−1 for the CuNWs/PDMS composite. Theoretical analyses suggest the potential for achieving even lower thermal resistance values with optimized LM wetting thickness while the accuracy of the measurements can be further improved by pattering a heater on the backside of the 1 mm thick silicon reference substrate.