Thermally Detachable Expandable Microspheres/Silver Composite Films for PCB-Level Conformal EMI Shielding

Conformal electromagnetic interference (EMI) shielding, which enables integrate EMI shielding materials onto printed circuit board assemblies (PCBAs), has emerged as a promising alternative to traditional metallic shielding covers owing to its lightweight, thin and conformal characteristics. In this work, high-performance silver flake/thermally expandable microsphere/thermoplastic polyurethane composite films (TDF) were designed for detachable conformal EMI shielding technology. The incorporation of thermally expandable microspheres engendered a segregated conductive architecture within the TDFs, yielding an optimal balance of prominent elongation at break (>500%), high electrical conductivity (>6000 S/cm), and exceptional EMI shielding effectiveness (>90 dB). Moreover, the TDFs demonstrated the capability for on-demand thermal detachment from PCBA substrates by heat treatment. This approach offers a novel strategy for designing repairable conformal EMI shielding materials suitable for next-generation consumer electronics.