An ultra-light and high electromagnetic shielding effectiveness material based on melamine foam with its skeleton metallized

Abstract

In this paper, an ultra-light and high electromagnetic shielding effectiveness (SE) composite material based on melamine foam with its skeleton metallized was prepared via electroless silver plating techniques. Salt-based colloid palladium was applied as the activator to modify the foam skeleton. X-ray photoelectron spectroscopy was used for tracking the Pd activated process. The effects of silver plating time, dynamic and static electroless plating conditions on the surface morphology, electrical and EMI shielding properties were investigated. The silver content in the foams subjected to electroless plating for different time was measured by thermo gravimetric analysis. Crystal structure of the silver nanoparticles was examined by the X-ray diffraction (XRD). Results show that a dense, uniform, consecutive silver layer forms on the surface of foam skeleton with the electroless silver plating time increases. A relatively dynamic electroless plating conditions do not help to construct a complete silver layer without cracks. The conductivity and SE of the foams is enhanced with the extension of silver plating time. The foam just containing 63.5 wt% silver achieves a minimum resistivity of 0.06 Ω cm and a SE of above 90 dB at the frequency range of 0.05–18 GHz. The foam prepared under a dynamic electroless plating condition exhibits lower SE than that under a static electroless plating condition. The XRD pattern shows the deposited silver coating exists as a typical face-centered cubic crystalline structure and the average crystal size is 14.4 nm. All results imply that such conductive melamine foam exhibits excellent electrical and EMI shielding properties, which can be used in a broad application range.