Hierarchical Synthesis of Particulate Thermal Interface Materials

A novel and computationally efficient analysis procedure is developed and applied to design particulate composites in general, and thermal interface materials in particular, in the present paper. The procedure is based on constructing complex behavioral fields through Boolean operations (compositions) on primitive fields. It is demonstrated that the Boolean operations and an associated meshless implementation efficiently model topological changes caused by the modification/rearrangement of the second phases in the heterogeneous material microstructure. The developed method was applied to evaluate the effective thermal conductivity of the thermal interface material. The inclusions in the microstructure of the thermal interface material are modeled through inclusion dominated Boolean union operation. A unit cell strategy is coupled with the constructive analysis to simulate the microstructure and to evaluate the effective properties. Thirty three-dimensional simulations of random arrangements of the heterogeneous microstructure at a fixed 58% volume fraction were carried out. The microstructures were systematically characterized using void nearest surface exclusion probability functions. The results of the simulation range within 10% with the fifteen experimentally measured values of an identically constituted system. A Pareto-optimal design procedure for studying the trade-off between the thermal conductivity and the viscosity was developed. The optimal volume fraction of the filler against increasing importance of viscosity (as quantified by its weight in the objective function) was determined. The trade-off curves represent optimal design solutions for various acceptable viscosity values