Rheological Engineering of Bimodal h-BN/Al2O3-Filled Epoxy Composites for Directional Thermal Management

Epoxy resin is widely used in semiconductor packaging because of its processability, adhesion, and electrical insulation. However, its low thermal conductivity limits heat dissipation and reliability under thermal cycling. To address this limitation, this study investigates a moldable thermally conductive epoxy composite using hexagonal boron nitride (h-BN) and spherical alumina (s-Al₂O₃) in a Bisphenol F diglycidyl ether (BFDGE) matrix.
The total filler content was varied to examine the relationship between filler loading, rheological behavior, and thermal properties. As the filler content increased, stronger interparticle interactions caused a transition from liquid-like to solid-like behavior. Rheological behavior, thermal conductivity, and fracture morphology were characterized using standard analytical methods.
Based on the observed moldable behavior, a layered thermal management structure was designed by combining an aerogel/epoxy thermal insulation layer with a ceramic/epoxy heat-dissipation layer. This structure can help guide heat flow in a designed direction while maintaining mechanical stability. Therefore, the developed composite shows potential for applications in semiconductor packaging, power modules, thermal interface materials, and free-form thermal management parts that require both heat control and structural reliability.