The Fluoro Surf® FG-3000 series, specifically designed for moisture-proof, waterproof, and acid-resistant applications on printed circuit boards (PCBs), exhibits excellent moisture resistance and electrical insulation properties. It demonstrates high performance as an insulating and moisture-proof coating for circuit boards and electronic components, as well as an acid- and corrosion-resistant coating.
Conventional water- and oil-repellent treatments generally suffer from poor mechanical film properties and are prone to cracking under thermal shock. As a result, products available on the market are typically limited to a film thickness of approximately 1 μm (at a resin concentration of 2%). Table 1 lists water vapor transmission data categorized by coating type and film thickness. From this table, it is evident that moisture resistance is proportional to film thickness. Therefore, when the film thickness is below a few micrometers, even fluoropolymer films with high intrinsic moisture resistance cannot exhibit sufficient performance.
The Fluoro Surf® FG-3000 series can easily form coatings with a wide range of thicknesses, from several micrometers to several tens of micrometers or more. Even at high film thicknesses, the coatings can withstand thermal cycling without cracking, thereby delivering excellent moisture- and water-proofing performance.
LED lighting is increasingly replacing incandescent and fluorescent lamps due to its low power consumption and long service life. However, the brightness of thin-type LEDs may gradually decrease over time. The structure of an LED includes a silver-plated reflector on the back of the light-emitting element, which efficiently directs light forward (Figure 3). The light-emitting element is encapsulated with silicone resin; however, trace amounts of hydrogen sulfide present in the atmosphere can permeate the sealing resin and cause sulfurization of the silver reflector. This results in the formation of silver sulfide, turning the surface black and reducing reflectivity, leading to decreased brightness.
This phenomenon occurs more readily in surface-mount thin-type LEDs because their encapsulation resin is thinner than that of bullet-type LEDs. As a countermeasure, several coating resins were evaluated, and fluoropolymer coatings were found to be the most effective. Figure 4 shows silver-plated LED substrates exposed to an air environment containing 15–20 ppm of hydrogen sulfide. Without coating protection, the silver surface rapidly sulfurizes and turns black, whereas no noticeable change is observed on coated samples.
These results demonstrate that fluoropolymer coating products are effective in preventing LED sulfurization, and they have already been successfully applied in many practical applications.
