Sheng-Chang Ding,Jian-Feng Fan,Dong-Yi He,Lin-Feng Cai,Xiang-Liang Zeng,Lin-Lin Ren,Guo-Ping Du,Xiao-Liang Zeng,Rong Sun
The emerging applications of composite gels as thermal interface materials (TIMs) for chip heat dissipation in intelligent vehicle and wearable devices require high thermal conductivity and remarkable damping properties. However, thermal conductivity and damping properties are usually correlated and coupled each other. Here, inspired by Maxwell theory and adhesion mechanism of gecko's setae, we present a strategy to fabricate polydimethylsiloxane-based composite gels integrating high thermal conductivity and remarkable damping properties over a broad frequency and temperature range. The multiple relaxation modes of dangling chains and the dynamic interaction between the dangling chains and aluminum fillers can efficiently dissipate the vibration energy, endowing the composite gels with ultrahigh damping property (tan δ > 0.3) over a broad frequency (0.01 – 100 Hz) and temperature range (–50 – 150 °C), which exceeds typical state-of-the-art damping materials. The dangling chains also comfort to the interfaces between polymer matrix and aluminum via van der Waals interaction, resulting in high thermal conductivity (4.72 ± 0.04 W m –1 K –1 ). Using the polydimethylsiloxane-based composite gel as TIMs, we demonstrate effective heat dissipation in chip operating under vigorous vibrations. We believe that our strategy could be applied to a wide range of composite gels and lead to the development of high-performance composite gels as TIMs for chip heat dissipation.
Problems of leakage and low thermal conductivity of phase change materials (PCMs) limit their applications to practical thermal management systems. To overcome these obstacles, a series of flexible composite phase change materials (FCPCMs) of silicone rubber (SR)/paraffin@melamine-formaldehyde resin (Pa@MF) microcapsules/expanded graphite (EG) were prepared in this study. The prepared FCPCMs showed significantly improved normal thermal conductivity with a value of 2.357 W/(m·K) at a microcapsule mass fraction of 25 % and EG mass fraction of 20 % (FCPCM-20), which are 1339 % higher than that of pure SR. Furthermore, the composite has excellent thermal buffering and heat dissipation capability. In the chip thermal management test, FCPCM-20 can significantly reduce the operating temperature of the chip, which is 66.77 % lower than that of SR. By comparing with the sample that only has added an equal amount of EG, the temperature reduction at heating powers of 10 W, 15 W and 20 W reached 19.80 %, 22.79 %, and 23.53 %, respectively. The results demonstrate that the fabricated composites possess superior thermal buffering and thermal regulation performance, showcasing great potential of applications to chip thermal management such as heat dissipation.
Wen Zhang,Wenchao Chen,Xiaoqin Ma,Yanfu Feng,Xiangpeng Geng,Qin Gong,Dekai Guan,Yaxin Liu,Bin Ma
The thermal management of highly integrated chips under high thermal flux density is hindered by disordered high-thermal-conductivity matrices that reduce phonon transport efficiency. To address this challenge, this study employs directional freezing to systematically align multi-walled carbon nanotubes, thereby establishing efficient thermal conduction pathways. Subsequent vacuum impregnation with the CaCl 2 ·6H 2 O phase change material (PCM) yields a composite material with pronounced anisotropic thermal conductivity—6.86 W·m −1 ·K −1 along the axial direction and 0.08 W·m −1 ·K −1 along the radial direction. This structural design not only enhances axial heat transfer and accelerates thermal equilibrium, but it also significantly suppresses PCM leakage via nanoconfinement and capillary effects, accelerating its phase transition by reducing subcooling to 11.41 °C. When employed for the transient thermal management of CPUs, the proposed material effectively directs heat flow, resulting in a 24 °C reduction in peak core temperature and a 19.5 °C reduction in peak surface temperature. Furthermore, this material demonstrates excellent thermal stability over 20 thermal cycles, with a maximum temperature fluctuation of only 5.2 °C. This study thus presents an effective strategy for the development of high-performance, structurally controllable PCM-based thermal interface materials.
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