Fabrication of oriented hBN scaffolds for thermal interface materials

Abstract

Thermal interface materials are widely used in thermal management, and usually require a high thermal conductivity, low coefficient of thermal expansion (CTE) and adequate softness. Herein, hBN/PDMS composites are fabricated by the infiltration of a PDMS prepolymer in the hBN scaffolds followed by a thermal curing process. The scaffolds are prepared by an ice templating method with hBN microplatelets, leading to a good alignment of hBN platelets along the z direction in the PDMS matrix. This unique structure results in a high thermal conductivity, which is about 3 times higher than that of the composites fabricated by a casting method, and the thermal conductivity is as high as 1.4 W m⁻¹ K⁻¹ along the z direction at ∼20 wt% of hBN microplatelets. The composites also possess low CTEs which are <100 ppm K⁻¹ along the z direction and maintain an adequate softness.