Quote:
Originally Posted by chrisridd
I don't know how the HZO coating works - is it on the whole assembled internals, or on subassemblies that get joined together? The HZO website does mention subassemblies, but that may not apply to Kobo's devices.
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It's a coating on the final fully assembled board. Seems to be just a modern version of the late 1930s (or maybe early 1940s) lacquer or varnish coating called tropicalization. Later the actual bare PCBs often had a "procoat" (protective coating) screen printed on that covered the tracks but not the solder pads (common since 1960s, though PCBs date from 1950s). The HzO like all tropicalization is an additional coating after soldering and assembly so gives the effect as if cables (and SD card if there is one) are glue in. The USB connector contacts are masked during application and usually gold plated anyway. Tropicalization, procoats and conformal coatings are synonyms and may be applied by a spray or dip.
Interestingly, car spray paints (including clear top coats) are slightly porous so zinc plating of the steel is needed. Boats and ships are in a hazardous environment so yacht "varnish" is polyurethane. The two part version or single can version will DIY waterproof better than HZO but takes ages to dry/set so is never used for consumer electronics. The switches and internal connections have to be inherently waterproof. External connections need to be suitably plated (gold isn't the only option).
Two part epoxy paint is used in some cases, especially if polyurethane would peel.
https://www.yokogawa.com/us/library/...opicalization/
https://www.ifotec.com/en/tropicaliz...tronic-boards/
HZO is just one of many companies selling protective coatings for electronicss. Nothing unique or new.
https://en.wikipedia.org/wiki/HZO
Nanotech is misleading. You maight as well call traditional lacquer known as shellac (literally made from the secretions of the Lac insect) a nanotechnology.
https://en.wikipedia.org/wiki/Shellac
https://en.wikipedia.org/wiki/Kerria_lacca Also provides a red dye.
It isn't true waterproofing as salt water, solvents, bath salts and detergents will degrade it. Hence a few minutes of very shallow immersion in anything other than pure water, and the need to rinse well afterwards.
There are cheap consumer products with real waterproofing. They will have rubbery bungs or covers for any connectors, or sealing rings on battery hatches.
Edit:
Nail polish remover (acetone) softens and dissolves the thick HZO coating at the internal SD card. It needs quickly rinsed off or it will dissolve other stuff. Alcohol (Meths or IPA*) seems too slow.
(* Not India Pale Ale, but the iso-propranolol used in electronics PCB cleaning).