Boron Nitride/Fluorinated-Polysiloxane Composite Films with Superior Thermal Conductivity and Hydrophobicity for Microelectronics Thermal Management

A series of boron nitride/fluorinated-polysiloxane (m-BN/f-PSi) composite films was designed and developed for effective thermal management and moisture resistance of microelectronic devices. Fluorinated-polymethylhydrosiloxane (f-PMHS) was synthesized via a ring-opening copolymerization of 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane and 1,3,5,7-tetramethylcyclotetrasiloxane. The biobased curing agent allyl-functionalized magnolol (allyl-Magnolol) was synthesized via the Williamson reaction. The modified BN (m-BN) with methacryloxy functional groups was prepared by reacting with γ-methacryloxypropyltrimethoxysilane (KH-570), which was subsequently mixed with f-PMHS and allyl-Magnolol. Subsequently, the m-BN/f-PSi composite films were fabricated by using the above mixture through a curing process followed by hot pressing. With an optimized loading level of 30 wt % m-BN, the composite film exhibits in-plane and out-of-plane thermal conductivities of 2.35 and 0.70 W·m–1·K–1, respectively. Additionally, the water contact angle of the film is measured at 136°. Thermogravimetric analysis also shows that the composite film has an increased onset degradation temperature of 343 °C (Td,5%, defined as the temperature corresponding to 5% mass loss) and a char yield of 63.0%. m-BN/f-PSi composite films offer a favorable combination of high thermal conductivity, excellent hydrophobicity, and sufficient thermal stability, making them highly promising candidates for thermal management applications in microelectronic devices.