UV-curable, 3D printable, thermally conductive polysiloxane composites for thermal interface devices

Abstract

Thermally conductive polysiloxane composites play an important role in 5 G electronics to efficiently dissipate accumulated heat. However, these polysiloxane composites are still challenged by long curing time, high energy consumption and huge amounts of waste from traditional subtractive manufacturing processes. In this work, UV-curable, 3D printable, thermally conductive polysiloxane composites are developed using mercaptopropyl-functionalized polydimethylsiloxane (PDMS-SH) and 2,4,6,8-tetravinyl-2,4,6,8-tetramethylcyclotetrasiloxane (V₄) as matrix, and different sized spherical Al₂O₃ and BN particles as thermally conductive fillers. Using V₄ instead of the common vinyl-terminated polydimethylsiloxane (PDMS-Vi) can greatly reduce the viscosity to fill more fillers (6 wt% BN and 76 wt% Al₂O₃) for higher thermal conductivity (2.02 ± 0.02 W/mK). The rational combination of larger particle size BN (200 μm) with different sizes of Al₂O₃ (5 and 90 μm) has a fast gelation behavior (within 5 s) and low critical exposure energy (3 mJ/cm²). Furthermore, the composites developed can be 3D printed into thermally conductive devices with complex 3D structures, and the 3D objects show outstanding heat conduction and dissipation capabilities. Therefore, these UV-curable, 3D printable, thermally conductive polysiloxane composites will be used in 3D thermal interfacial objects with high production efficiency, low energy consumption and customization.