Meshtastic

Epoxy as a Case?

Hi All,

Looking to potentially by a unit, hoping some hunting buddies will get into it to for when we don’t have cell communication etc.

Although I do have access to 3D printing, I worry about waterproofness… I’m wondering would there be any issues with doing an epoxy pour to encase the electronics, maybe including a thin layer over the screen? I’d have to figure out what I would do with the battery set up, but otherwise it seems attractive, and I have epoxy. My only concern would be epoxy acting like an insulator and causing overheating issues.

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What you’re talking about is called a conformal coating.

You can purchase products for it on Amazon but if you really want to go cheap, buy a bottle of clear nail polish from the dollar store.

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Hmm I was thinking a bit beyond that. I was thinking something I could have the screen embedded in as well, so not just a thin coating, but actually pour an epoxy rectangular prism with the pcb etc inside.

May be worth trying.

I’d be concerned about what the additional dielectric would do to the tuning of the RF paths on the PCB.

It would look really cool.

Do you think if I did a conformal coating first that would mitigate any of that? I’m no expert on the dielectric end of things so that may be an irrelevant question.

A dielectric is an insulator. The RF traces of the PCB was designed with air as the dielectric on one side of the circuit and fiberglass epoxy (the core of the pcb) on the other.

Adding a significant amount of anything other than air will change things.

This is one of those gray areas where doing RF design is almost black magic. For a given design, you have a few rules of thumb to work with. Stepping outside of that, you just gotta try it, run tests and try again.

If I were to bet, I would guess that it should work to be fully encased in epoxy.

If conformal coating is not enough, then potting could be the way. Many variants are on the market - from soft (gel or silicone type) to super hard (epoxy).

Yes potting is exactly what I’m thinking about.

Potting has been used for years - we were putting automative and defence gadgets in black epoxy resin 30 years ago (including RF stuff). My only advice … check you tested it and wired it up fully first :slight_smile:

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