Electromagnetic interference shielding effectiveness of electroless Cu-plated PET fabrics

In order to develop the high quality electromagnetic interference (EMI) shielding textiles for protective clothing, polyester fabrics were electroless copper-plated. Effects of pretreatment conditions such as scouring, etching, and catalyzation on electromagnetic interference shielding effectiveness (EMISE) and physical properties of treated fabrics were investigated. High EMISE of fabrics over the wide range of frequency level were obtained when fabrics were scoured with 0.3% NaOH and 1.0% Triton X-100, and etched with the mixture of HCl/HNO₃ at 25°C for 30min before activation. We found that KCl was the better catalyst activator than commonly used SnCl₂. EMISE of copper-plated fabrics increased as the concentration of KCl increased up to 1:8 molar ratio of PdCl₂:KCl then decreased with further addition. As the catalyzation temperature increased from 25 to 40°C, the EMISE of copper-plated fabrics increased, whereas their EMISE reduced to about zero when the activation temperature exceeded over 40°C. Physical properties including tensile extension and drape stiffness of copper-plated fabrics are higher than those of the untreated PET, but tensile strength was slightly decreased. By scanning electron microscope (SEM), we found special fracturing behavior of the copper-coated PET fabrics due to the ductility and brittleness of copper film on the PET fabric.