Effective thermal contact conductance of encased silicon ball from molecular dynamics simulations

The heat dissipation performance of point-contact structures in many micro/nano-devices is critical. In this study, the effects of the normal load and diameter of the silicon ball on the effective thermal contact conductance (Geff) of the encased silicon ball between two silicon plates were studied by using the non-equilibrium molecular dynamics method. The results show that increasing the normal load increases the real contact area between the silicon ball and silicon plate, and thus improves the transmission channel and the density of states of low-frequency phonons, resulting in the observation that the Geff increases with increasing normal load. It is also found that the Geff is not sensitive to the diameter of the silicon ball from 2.66 to 4.16 nm at low normal load due to the competition between the enhanced interfacial thermal conductance across the contact region and the reduced internal thermal conductance of the silicon ball. The variation of Geff in the encased silicon ball structure with the external load and diameter has important guidance for the packaging and thermal design of micro/ nano-devices.