Diamond-reinforced thermal paste as the thermal interface materials for passive cooling applications

As thermally conductive fillers for thermal interface materials (TIMs), synthetic diamond has not been as popular as graphite-like carbon materials due to their economic viability. However, advancements in the synthesis technique significantly brought the cost of synthetic diamond down, and the price is projected to decrease further in the future. As such, synthetic diamond particles can now be economically considered for reinforcing TIMs. In this study, we incorporated synthetic diamond particles in commercially available silicone-based thermal paste for TIM application between a copper heat sink and a light-emitting diode (LED). Despite the increase in bondline thickness, the LED operation temperature gradually decreased. At 30 wt% loading, there was a 6-fold thermal conductivity increase, lowering the LED temperature by 3 °C and reducing the respective heat dissipation by 7%. These results show positive prospects regarding the use of synthetic diamond in this field, as its high isotropic thermal conductivity will offer a distinct advantage over graphite-like carbons, which require orientation control due to their anisotropy.