The coating, which the folks at Daikin say is environmentally friendly, is a fluorinated solvent. The components are simply dipped in the solvent and then left to dry, a process that takes approximately one minute at room temperature.
A spokesman for the company explained (translation by Diginfo):
This product isn’t intended for full waterproofing, but for raising the baseline in waterproofing to everyday standards. So we’re suggesting this coating as a way to reduce the risk of phones malfunctioning if they happen to get dropped in water.
This product is made by dissolving a fluoropolymer in a fluorinated solvent. The fluoropolymer is nonflammable and has low toxicity. By using this solvent, which isn’t subject to any particular regulations, we’ve achieved a coating that’s environmentally friendly.
Protection from water and moisture is achieved using a film thickness of between 0.1 micron and 1 micron – because it is so thin, it can also be used to protect speaker mesh and earphone jacks.
Personally, I have never managed to drop my phone in water, but I know a few people who have and while it is possible to rescue most phones after a brief immersion, a little extra protection never went astray. If it is environmentally friendly and doesn’t add too much more to the overall cost of production then I am all for it.