Abstract: A method for waterproofing a device and the resulting device are provided. The device includes a printed circuit board assembly (PCBA), which includes a printed circuit board, and at least one electronic component disposed on the printed circuit board. A waterproof coating such as a polymer coating is disposed on or in contact with at least one portion of the at least one electronic component. A nanofilm is disposed on the PCBA. The nanofilm includes an inner coating and an outer coating. The inner coating is disposed on the printed circuit board or in contact with the waterproof coating. The inner coating comprises metal oxide nanoparticles having a particle diameter in a range of about 5 nm to about 100 nm. The outer coating in contact with the inner coating, and comprises silicon dioxide nanoparticles having a particle diameter in a range of 0.1 nm to 10 nm.

Abstract: A method includes steps of forming an inner coating on an object and forming an outer coating in contact with the inner coating. A first solution including metal oxide nanoparticles and a first solvent is applied onto the object. The first solvent is removed to form the inner coating with the metal oxide nanoparticles. A second solution having silicon dioxide nanoparticles and a second solvent is applied onto the object. The second solvent is removed to form the outer coating with the silicon dioxide nanoparticles. The interfacial binding force between the metal oxide nanoparticles and the silicon dioxide nanoparticles is then strengthened, for example, by applying a third solution such as water, ethanol or a mixture thereof to the inner coating and the outer coating.