Unveiling the Degradation Mechanism of Polymer-Based Thermal Interface Materials Under Thermo-Oxidative Condition

With the growing power density and miniaturization of electronic devices, their thermal management and reliability are becoming more and more important. Polymer-based thermal interface materials, which are used to fill the gap between chip and heat sink, play an important role for the heat dissipation, but their reliability is rarely studied in academia, especially under thermo-oxidative condition. Here, a polymer-based thermal interface material, highly filled thermal conductive gel, is used as a model to study the degradation mechanism under thermo-oxidative condition. The results show that aging mainly deteriorates the mechanical performance instead of its intrinsic thermal conductivity. The elongation at break of aged sample is reduced and the corresponding modulus is increased as a function of aging time. Relaxation spectra indicate that the relaxation time of aged sample increases. The longer relaxation time of aged sample is attributed to the chain scission and oxidation of alky chain at interface and the depolymerization of polydimethylsiloxane chain, resulting in a more crosslinked polymer network. Thus, both interfacial aging and depolymerization of polymers contribute to the slowdown of polymer chain dynamics and degradation of mechanical properties. This work provides an insight into the degradation mechanism of thermal interface materials and guides the development of high-reliability thermal interface materials.