Absorption-Driven Near-Field EMI Shielding of Si-CNT Composite for LED Displays: A Solution for the Transition from Reflective Inefficiency to Absorptive Suppression

The issue of near-field electromagnetic interference (EMI) is being made worse by the widespread use of highly integrated electronic devices, including commercial LED displays. Although highly conductive pristine carbon networks, like recycled carbon fiber nonwovens (rCFNWs), have excellent far-field shielding effects (~43 dB) in theory, their purely reflection-oriented mechanisms cause severe secondary signal interference in practical near-field applications due to reflective inefficiency. This study suggests employing a custom-formulated silicone-carbon nanotube (Si-CNT) composite to switch to an absorption-based shielding mechanism in order to get around these restrictions. This study used FE-SEM, Raman spectroscopy, XPS, ICP-AES, FTIR, and TGA-DTG to systematically investigate the morphological, chemical, and thermal properties of the rCFNW, Si-CNT composite, and a Cu-integrated variant (Si-CNT-Cu). Surface reflection was greatly reduced by adding CNTs to the silicone matrix, converting the materials into absorption-oriented localized shielding composite materials (~16 dB). Both the designed Si-CNT membrane and the Cu-integrated Si-CNT-Cu product totally eliminated the 850 MHz switching noise peak (>40 dBuV) in real near-field tests of commercial LED modules running under worst-case conditions (5.36 A). Additionally, the bare Si-CNT membrane showed a lower coefficient of thermal expansion (CTE) in the thermomechanical analysis (TMA) than the Si-CNT-Cu product. On the other hand, the macroscopic integration of Cu wires in the Si-CNT-Cu composite provided remarkable thermomechanical stability, preventing thermal softening by preserving an exceptionally high storage modulus of 97.54 MPa at 198 °C, according to dynamic mechanical analysis (DMA). These findings show that using absorptive suppression to overcome near-field inefficiency is a very successful method for creating dependable EMI shielding composite materials in high-power electronic systems.