Is there a standard process to pour conformal coating, similar to potting, but then drain the excess? The benefit of draining the excess is to reduce weight and get better cooling.
From my limited experience, potting usually involves pouring a solid block of 2-part epoxy or urethane in an electronic enclosure. Even with thermal fillers, the thermal resistance is typically high which results in reduced cooling. 2-part potting compounds are required because the solid block won't air-cure and the 2-part compounds add to process costs.
Conformal coating on the other hand is typically sprayed (resulting in spray shadows) or dipped (which doesn't work for enclosures).
I've never seen it done but it makes sense to pour a 1-part low viscosity conformal coat using a process similar to potting but then remove the excess by either pumping out or draining the cavity. Like a dipping process, the excess would be recycled for subsequent parts. Since the resulting coat is thin, a 1-part air-cure compound can be used.
Does anybody have experience or comments?
Best Answer
I've used Plasti Dip for very small quants w/ success on assembled boards <1 in sq. about 3-4 years ago and the assemblies have lasted to the present. I don't know how this would scale for larger boards, or for production. I used it because it wasn't a big deal if it failed, fast was more important than right, and I bought it off the shelf. Of course, if this is mission critical I'd recommend much more research.
Dow Corning has a conformal coating tutorial that you might find useful.