Ageing Characteristics of Novel Thermal Interface Materials Based on Poly(Ionic Liquid)s and Liquid Metal

Thermal interface materials (TIMs) play a crucial role in managing heat transfer in electronics. However, the high-density chiplet packaging also poses challenges to the mechanical reliability of TIMs. The conventional organic silicon system faces technical hurdles such as poor flexibility and weak adhesion, necessitating the development of next-generation TIMs. Previous studies have demonstrated that poly(ionic liquid)s (PILs) exhibit superior adhesion and mechanical properties compared to conventional polymer matrices, alongside self-healing capabilities. These characteristics make PIL-based TIMs feasible. To further validate their practical viability, in-depth studies on their thermal, mechanical, and reliability properties are needed. In this study, we investigated the preparation and aging behavior of TIM based on poly(ionic liquid)s and liquid metal. These TIMs were synthesized by simply combining PILs with liquid metal in solvent, followed by drying. Their physical characteristics, including thermal conductivity and mechanical properties, were thoroughly analyzed. To assess the reliability via aging characteristics of PILs-based TIMs, we employed X-ray chip inspection system to observe coverage variations of TIMs under different aging conditions. Our results show that these TIMs exhibit excellent thermal stability. After high temperature storage aging tests, the coverage of pure P[OVIm]NTf₂ and P[OVIm]NTf₂/LM (18 vol%) were maintained at 99.15% and 99.12%, respectively, with coverage decreases of only 0.84% and 0.71%. This minimal reduction in coverage demonstrates their suitability for practical applications. In summary, our study emphasizes the aging performance of poly(ionic liquid)s-based TIMs and underscores their potential as replacements for conventional organic silicon systems. This research provides valuable insights into the preparation of high-performance chip-level TIMs.