Depositing gradient thickness silver film on CNF/rGO/polyimide surface to form a sandwich structure for efficient electromagnetic interference shielding

Deployable satellites in space are exposed to high-frequency electromagnetic interference (EMI) for long periods of time, resulting in shortened lifetimes, so there is an urgent need for supportive electromagnetic shielding materials. To address this limitation, our team has developed innovative ultrathin carbon nanofiber/reduced graphene oxide/polyimide (CNF/rGO/PI) composites. It has excellent strength, shape memory properties, thermal stability and wide temperature range tolerance. Among them, polyimide with 4% CNFs and 4% rGO (CGPI44) has the best performance. Gradient-thick Ag films are deposited on both sides of the CGPI44 substrate by magnetron sputtering to form sandwich structure composites. With a sputtered Ag thickness of only about 5 μm and a total thickness of 0.146 mm, the material exhibited an extremely high electrical conductivity and excellent EMI shielding effectiveness (SE) of up to 112 dB in the 8.2-12.4 GHz band. Finite element analysis is performed to calculate the electric field strength and energy distribution. By providing a feasible scheme for highly effective shielding of high-frequency EMI, this approach will promote research on magnetron-sputtered polymer composites in the field of electromagnetic shielding.