Vapor-deposited environmental-friendly bilayer coatings with synergistic anti-corrosion effect for electronic device protection

Electronic devices working under harsh environments require protective polymer coatings that can resist the corrosion of their metallic components. Solvent-based polymer coating methods, however, are failing to meet the increasing demand by the trending miniaturization and high integration of devices. Here, we present an ultrathin bilayer conformal coating with excellent protection capability fabricated via a solvent-free initiated chemical vapor deposition method. The bilayer coating consists of a bottom barrier layer crosslinked through urea linkages and a short-fluorinated hydrophobic surface layer anchored by aromatic crosslinkers. The hydrophobic surface resists the adhesion of water and corrosive species while the barrier layer further inhibits their penetration. As a result, the bilayer coating exhibits superior anti-corrosion performance compared to single-layered coatings with a more than 10 3 -fold decrease in corrosion rate than bare copper and protection efficiency higher than 99.9%. Using an LED circuit board as a model device, the bilayer coating can be conformally deposited on different parts of the device. The bilayer-coated device endured 24 h working underwater, whereas device spray-coated with conventional polyurethane resin coating failed after 550 min, suggesting promising practical applications of the reported method in the protection of various electronic devices.