Thermal interface material of carbon fiber enhanced micro-nano Cu sintering for power module thermal management

The pursuit of higher power and density in wide bandgap power modules makes thermal management a critical challenge. Thermal interface materials (TIMs) play a critical role by filling microscopic air gaps and thereby enhancing heat transfer for power electronics. Combining the recent development of nano metal sintering technology and exceptional intrinsic thermal conductivity of certain carbon allotropes, micro-nano Cu sintering with carbon fiber (CF) reinforcement was promoted as potential high performance and cost-effective TIM for power modules. In this work, a Cu/CF composite paste was synthesized and sintered by the thermal-compressing process, followed by the detailed investigation and simulation on its sintered interfacial microstructure and mechanical and thermal properties. This work demonstrated a significant improvement of thermal and mechanical properties through the optimization of CF doping ratio. The addition of 5 wt. % CF increased the average shear strength of Cu sintering joints by 65.3% to 44.8 MPa, which is attributed to enhanced interface adhesion from the nano Ni particle coating on the CF surface. Thermal conductivity rose from 77.1 to 87.4 W/(m K) and 107 W/(m K) with 5 and 10 wt. % CF doped, respectively. Furthermore, adding 10 wt. % CF increased thermal diffusivity by 27.4%, which helps alleviate transient thermal loads. This work highlights the strong potential of Cu/CF composites as future TIM for high-density power modules.