Structure and property relationships in thermally conductive flake filled composites

Dielectric materials filled with thermally conductive particles have undergone significant development as candidates for thermal management in computational, high-power, and radio frequency electronics and devices. Specifically, particle-filled systems including thermal interface materials and polymer-ceramic composite encapsulants offer cheap, easy, and customizable solutions. Understanding the relationship between the microstructural design and emergent thermal conductivity of such composites can inform processing routes that realize drastically higher heat flow. To investigate the large variable space associated with these materials, finite element analysis is leveraged to systematically explore representative microstructures and establish causal links with emergent property outcomes. Here, several key structural parameters are isolated and investigated including filler aspect ratio, filler volume fraction, filler conductivity both with and without anisotropy, filler orientation, filler-matrix interface conductance, and matrix conductivity. The relative importance of each variable is discussed in detail. These findings can be utilized to tune resultant composite microstructures by adapting processing techniques, thus enabling higher effective composite thermal conductivity.