...for a bit of insulation. Are either of these available in a brush on bottle type of thing that you can get locally? I'm looking for something thin/clear so not that visible, but provides some insulation.
You guys mentioned NeverWet or Acryllic
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I saw some liquid tape at Walmart on their website, but it too is dark and not clear.
I guess more context as to what you want to do, then we can offer more suggestions, thus avoiding the X/Y problem.
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alank2 wrote:
... and UV resistance?
I'm looking for something thin/clear so not that visible, but provides some insulation.
IIRC, industrial NeverWet two-part is UV-tolerant.
Rust-Oleum® NeverWet® - Homeowner
NeverWet Superhydrophobic Coating Products | Hydrophobic Coating & Water Repellent Spray
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Overview | Experimenting with NeverWet + Electronics | Adafruit Learning System
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Its UV sensitivity means we'd have to reapply the coating frequently. The white chalky appearance and powdery feel might not work for all applications or uses, however overall we had fun experimenting!
Last Edited: Wed. Nov 18, 2020 - 02:20 AM
ki0bk - see the other thread about show your 2020 project. I've got a binaryEnigma that is a CR2032 project that is completely open. I'd like to prevent any higher current shorts with it which is mostly protecting one point before it goes through the PTC, but if something was thin to apply and not unsightly then perhaps the other pins as well.
https://www.avrfreaks.net/forum/...
I had envisioned not a "insulation coating", but a thick dip of some sort, like you see in bar table tops (where they coat over coins, beer caps, etc)...It's maybe 1/8 thick...was thinking you might be able to dip it to get the effect (otrmaybe pour into a mould.
https://www.pinterest.com/pin/42...
https://www.amazon.com/Crystal-C...
do a search for PCB keychain epoxy ...there's a ton of examples
Last Edited: Tue. Nov 17, 2020 - 07:50 PM
I see where you are going with that avrcandies - a gloop approach. Does anyone remember gloop (Christmas cartoon from many years ago where the antagonist wanted to cover all toys in solid gloop so they would never break or get old)? It certainly would make it keychain proof! I think I'd still like to have it more bare, but maybe I've got to try it to see what it looks like.
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A favorite of mine is DOWSIL™ 734 Flowable Sealant, a self levelling silicone rubber type. While having electrical properties specified there is no recommendation for electronic applications, as there is a corrosive effect with acetic acid being released during curing.
Data sheet attached, Dow product link https://www.dow.com/en-us/pdp.dowsil-734-flowable-sealant.01907506z.html
Other silicone sealants at McMaster-Carr https://www.mcmaster.com/sealants/container-type~tube/formulation~silicone/
Attachment(s):
Last Edited: Tue. Nov 17, 2020 - 06:26 PM
I was thinking of something that was a coating about as thick as the height of the chip or leds, but not too thick (why I was thinking of a dip), maybe like 20 pages of paper thick, so the shape is well maintained, yet the whole thing feels very smooth.
some tips: https://www.edn.com/artist-turns...
Last Edited: Tue. Nov 17, 2020 - 07:55 PM
Thanks avrcandies; that does look sharp.
What you want is CONFORMAL COATING:
https://www.henkel-adhesives.com...
I have used teh spray on stuff and it works very well.
https://www.henkel-adhesives.com...
Jim
What you want is CONFORMAL COATING:
That is somewhat thin...not what I was suggesting, but maybe that is in the consideration ring as well. In fact, our circuit board dept used or looked at parylene coatings, which require special deposition equipment---the thickness proposed was only around 1000 nanometers ---that's thin (But it works really great).
There are a bunch of "conformal coating" companies - MG Chemicals, Tech-Spray, etc. Aimed specifically at electronics, and in several choices of resin and coloration.
There are many MORE companies selling "casting resins" for artists and such. Alumilite, Smooth-on, Tap Plastics...
I don't know if there's anything specifically designed for "bulking up" a free-form circuit sculpture. Dipping seems like it would be really wasteful. I wonder if you could use multiple layers of some of the UV-curable 3d-printing resins?
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alank2 wrote:
brush on bottle type of thing
Women's clear nail top coat, from your local market.
Back when I was designing underground robots, we stashed the electronics in inconel tubes. Conformal coated and then filled with a flowable silicone inside a carbon fibre tube sized to slide into the inconel. We had to add polystyrene beads to the mix to provide space for thermal expansion. The entire thing was, in technical terms, bleedin' expensive, but it could stand being on arctic ice and three miles down a drill bore (and the careful handling of the riggers!).
Probably more than you need...
Neil
polystyrene beads to the mix to provide space for thermal expansion.
Oh! That's a neat idea!
> Women's clear nail top coat, from your local market.
I was thinking about trying this.
Or you could ditch the glue altogether and stick it in a nice enclosure like 1 of these CS75 cases. Has a 1 x CR2032 battery compartment and a lanyard loop hole. Looks the perfect fit for your Enigma. Sadly it doesn't come in a clear plastic so your fancy PCB solder mask colours will be lost. 
Cheers,
Steve
P.S. If you use Altium Designer, I have a component for the mechanicals for this case. 
Last Edited: Wed. Nov 18, 2020 - 09:59 PM
Dipping seems like it would be really wasteful
I was thinking it would be like dipping it into pancake syrup or warm honey & letting it dribble back into the can & then take away & harden, possibly repeating if needed.
I used to have some stuff like that to dip your pliers handles into--shockproof red!
>> Dipping seems like it would be really wasteful
I was thinking it would be like dipping it into pancake syrup or warm honey & letting it dribble back into the can & then take away & harden, possibly repeating if needed.
That'd work for a solvent-based coating, if you have a container with a nice, tight, lid. A lot of the more robust coatings are catalyst-activated.
My track record for storing various coatings and resins is pretty poor :-( If you have a lot to do in a relatively short time, it might work out.
For the people suggesting conformal coat what that is is just clear acrylic paint with UV coloration added so it'll show up under a black light during quality assurance inspection to keep the material off conductors/keep out areas.
If the UV isn't needed regular clear acrylic works for this.
Last Edited: Fri. Nov 27, 2020 - 09:05 PM
Um. "Conformal coating" is a generic term. One of the distributershas 29 PAGES of products in that category: https://www.ellsworth.com/produc...
I've got some third party units here for repair where the PCB has been coated on both sides with clear silicone sealant. The smoothness of the finish would imply that it must have been a pourable mix. I'm guessing that the two sides would have been done as separate operations.
I'm also guessing that it must be a neutral curing sealant as I don't think acid and PCBs mix.
Last Edited: Sat. Nov 28, 2020 - 08:01 AM