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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?

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  • \$\begingroup\$ @stevenvh It says 80% from here, unless he just in the last 30 minutes accepted a bunch of answers. \$\endgroup\$ – Shamtam Sep 5 '12 at 18:07
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    \$\begingroup\$ stevenvh: 100% now. Thanks for the feedback. \$\endgroup\$ – JimFred Sep 5 '12 at 18:07
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    \$\begingroup\$ Look at Dow Corning 2570. Dip/Brush/Spray. 0.1mm thick!!!. Wear a mask and ventilate well!!! \$\endgroup\$ – Russell McMahon Sep 5 '12 at 18:15
  • \$\begingroup\$ Russell: I searched for '2570' at dowcorning.com, got 'no result found'. Google didn't help either. Is there a prefix or suffix for that number? \$\endgroup\$ – JimFred Sep 5 '12 at 18:29
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    \$\begingroup\$ @Andrew - It's not about reputation, it's about appreciation. Upvoting and accepting is like saying "Thanks". I hit the daily 200 rep cap often, but I'm still happy with the upvotes which don't give me rep anymore. It's that thankfulness which motivates me. \$\endgroup\$ – stevenvh Sep 15 '12 at 17:54
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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.

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  • \$\begingroup\$ Would we be correct in declaring the solder mask as being a kind of conformal coating? It's a thin layer that protects circuit board components, namely the copper itself. (Not only from solder during wave soldering, but thereafter from the environment.) \$\endgroup\$ – Kaz Dec 14 '12 at 1:25
  • \$\begingroup\$ @Kaz a Conformal coating is traditionally used to cover the exposed parts after assembly. The exposed tracts and components are not protected by the solder mask in any way. The tracks covered by the solder mask are usually reliably protected unless corrosion or de-lamination takes place from exposed edges. +1 to Scott for the tutorial \$\endgroup\$ – KalleMP May 9 '17 at 10:46
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MGChemicals - they have pourable type.

I have also used "tooldip" which is used on tool handles.

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