Thermo-optical properties of packed nanoparticle thermal interface materials

Heat dissipation has become one of the biggest challenges to improving the performance, reliability and power density of electronic devices. One of the crucial components in electronics packaging that must be further developed to address this challenge is thermal interface materials (TIMs). Recently, packed SiO
₂
nanoparticles, which could serve as TIMs when embedded in a polymer matrix, have been shown to greatly enhance thermal transport due to near-field electromagnetic interactions. Here we investigate the optical excitations of these types of nanoparticle configurations by solving Maxwell's equations by applying the Finite Difference Frequency Domain technique. We show that near-field thermal energy enhancement between the nanoparticles is affected by different configurations of nanoparticles. We also show that by changing the particle spacing, the surface plasmonic effects could be tuned to achieve high absorption in a narrow spectral range, corresponding to a high density of states of thermal emission. Results are compared to first-principle calculations of the nearfield spectral thermal emission with excellent agreement. These results give insight into the electromagnetic interactions in high thermal conductivity packed particle beds and will aid in the design of new TIM materials.