| With the fast development of new energy vehicles and wearable devices in recent years,the excessive heat and inevitable vibrations are the two vital factors in the serious threats to the reliability of chips（e.g.,CPU and GPU）.Thermal interface materials are a key solution to transfer thermal energy efficiently from the back of the chip to the heat spreader.Thermal gels are widely utilized as TIMs because of their high flexibility,low cost,and easy process.To eliminate vibration interference and meet the heat dissipation requirements,there is an urgent need to develop next-generation TIMs that combine efficiently heat dissipation along with high damping and high resilience.This thesis mainly focuses on the difficulty of damping,thermal conductivity and resilience in TIMs.By using polydimethylsiloxane as matrix and aluminum powder as thermal conductivity filler,we fabricated TIMs with high damping and high thermal conductivity in a wide frequency and temperature range based on the molecular structure regulation design.The TIMs with high thermal conductivity and high resilience was prepared by in-situ modification of thermal conductive filler.This thesis focuses on the coupling relationship between damping,resilience and thermal conductivity in silicone TIMs.The specific research is summarized as follows:（1）Preparation and properties of TIMs with high thermal conductivity and high dampingComprehensively considering Maxwell theory and dynamic interaction,we report a polydimethylsiloxane（PDMS）-based thermal gels integrating high thermal conductivity and remarkable damping properties,by introducing dangling chains into PDMS network.The introduction of suspension chains adds new relaxation mode units,leading to a broadening of the relaxation spectrum.We achieve multi-level control of the dissipation of the energy layer of the material through multi-scale control of the molecular relaxation time.Thermally gels with ultrahigh damping properties（tanδ>0.3）over a broad frequency（0.01～100 Hz）and temperature range（-50～150℃）.Thermally gels show good thermal conductivity(4.72 W m-1 K-1)and low thermal resistance(0.49 K cm2 W-1)and maintained good flexibility,elongation at break up to131%,Young’s modulus is only 89 KPa.We confirm that it can effectively dissipate heat as TIMs in chips working under severe vibration,showing excellent heat dissipation performance and thermal stability.（2）Preparation and properties of TIMs with high thermal conductivity and high resilienceThe TIMs with high thermal conductivity and high resilience was prepared by in-situ modification of the coupling agent used in the thermal conductivity packing to improve the dispersibility of the packing.We mainly analyze the influence of the dispersion of filler in the matrix and the interaction of polymer matrix on the mechanical and thermal conductivity of the TIMs.The elongation at break of DTS-5000 is 125%,the toughness is 831.45 J m-2,and the strain recovery rate is 75%.We performed a drop ball simulation experiment on the DTS-5000,which showed the same excellent damping performance and ultra-high energy dissipation as the M500.The DTS-5000 showed good thermal conductivity(3.42 W m-1 K-1)and as TIMs,it exhibits thermal shock stability in the 1200 cycles of the T3Ster cycle,demonstrating excellent heat dissipation ability and thermal management application potential.This work provides a new perspective to solve the problem that TIMs cannot have both high thermal conductivity and elastic energy. |
