Military electronic equipment is often subjected to harsh operational environments characterized by mechanical shocks, vibrations, and rapid temperature fluctuations. Therefore, reliably protecting internal components is crucial. To ensure system reliability, potting materials must provide both mechanical cushioning and environmental stability. While polydimethylsiloxane (PDMS) is a promising option due to its excellent flexibility, chemical stability, and environmental resistance, its low thermal conductivity limits its effectiveness in thermal management. In this study, we aimed to address these limitations by fabricating aluminum nitride (AlN)/PDMS composite potting materials. We evaluated their thermal and mechanical properties based on varying filler loadings. PDMS specimens with different AlN contents (0, 5, 10, and 20 wt%) were prepared, followed by systematic compressive tests and thermal conductivity measurements. The results indicated that both compressive strength and thermal conductivity improved consistently with increased AlN filler loading, achieving up to a 46.7% enhancement in thermal conductivity while reasonably maintaining the inherent elasticity of the elastomer. These findings suggest that AlN/PDMS composites can effectively serve as protective materials that meet the thermal management and mechanical cushioning requirements of defense electronics, providing a foundational guideline for designing military-grade potting materials.