An Innovative Way to Make Anisotropic Thermal Interface Materials

We present an innovative strategy to increase the through-plane thermal conductivity of TIM pads. In silicone matrices using several types of ceramic fillers, we demonstrate significant improvement in through-plane thermal conductivity. CondAlign's patented technology is based on dielectrophoresis. The process uses an external electric field to align and orient particles in polymers, resulting in anisotropic conductive films. By applying the electric field before polymerizing the matrix, particles dispersed in a polymer resin become polarized, and chain formation occurs due to dipole-dipole interactions between nearby particles. The effect of alignment is most pronounced for anisotropic particles such as hexagonal boron nitride (hBN), where controlling the particle orientation is particularly beneficial. We show that orienting the more conductive longitudinal axis of the hBN particles along the Z-axis of the TIM pads can lead to significant thermal enhancement. We also discuss optimal particle loading and show that our technology is most efficient at relatively low particle concentrations. This technology has the potential to provide both cost-saving solutions and improved performance. The first by retaining a given thermal conductivity with a lower amount of expensive filler particles, the latter by improving thermal conductivity at a given filler content.