High-Adhesion Ag Film with Enhanced Electromagnetic Shielding Performance via Post-Treatment of a Polydopamine Adhesive Layer

Low adhesion limits the application of the conformal metal coating based on metal-organic complexing deposition (MOD) ink in electromagnetic interference shielding with an ultrathin thickness and excellent electromagnetic shielding performance. Here, the mussel-inspired polydopamine (PDA) coating with double-sided adhesive characteristic was used to modify the substrate surface, and a high-adhesion silver film was prepared by spin-coating MOD ink on the PDA-modified substrate. The surface chemical bond of the deposited PDA coating was found to change with the exposure time under air in this work, and three post-treatment methods were carried out on the PDA coatings, including exposure to air for 1 min, exposure to air for a day, and oven heat treatment. The influences of such three post-treatment methods of PDA coating on the structure of the substrate surface, the silver film adhesion property, the electrical property, and the electromagnetic shielding property were studied. The adhesion of the silver film was effectively enhanced up to 20.45 MPa by controlling the post-treatment method of the PDA coating. The PDA coating was found to increase the sheet resistance of the silver film and to absorb electromagnetic waves. By optimizing the deposition time and the post-treatment condition of the PDA coating, superior electromagnetic shielding effectiveness up to 51.18 dB was obtained with a thin silver film of 0.42 μm. The introduction of the PDA coating improves the applicability of the MOD silver ink in the field of conformal electromagnetic shielding.