Surface wrinkles enhancing electromagnetic interference shielding of copper coated polydimethylsiloxane: A simulation and experimental study

• Wrinkles for EMI shielding are evaluated by a simulation and experimental study. • The wavelength and amplitude of wrinkles can be easily regulated. • Wrinkles improve the EMI SE values and reduce the R values for the composites. • Wrinkles affect distributions of current density, electric and magnetic field. • Wrinkles enhance conduction loss, interface polarization, Salisbury screen effect. Herein, the sandwiched copper/polydimethylsiloxane/copper (Cu/PDMS/Cu) composites with periodic micro-wrinkles were fabricated by a Cu sputtering deposition on the surface of the stretched PDMS substrates. The effect of Cu micro-wrinkles on electromagnetic interference shielding effectiveness (EMI SE) was evaluated by a simulation and experimental study via tuning pre-stretching strain and thickness of PDMS substrates. The results show that the EMI SE values increase with the increase of pre-stretching strain of substrates due to the formation of more micro-wrinkles on the surface. The shielding mechanism of the sandwiched Cu/PDMS/Cu composites with micro-wrinkles was also discussed in this study. The micro-wrinkles can induce the heterogeneous distribution of surface electrons, and then enhance conductive loss and multiple scattering of electromagnetic waves (EMW) on the surface. In addition, the micro-wrinkles also increase the surface area of the composites which enhance the Salisbury screen effect and then reduce the reflection of microwaves.