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silicone glue for potting my high power led system?

I'm working on a portable high power LED system and I'm thinking of potting it in silicone for durability. It is gonna get banged around a lot... 

I need a little guidance.

I've searched the internet and I can't figure out what silicone to buy? I'm looking for something as cheap as possible, but it needs to dry clear and feel somewhat like rubber when it is dry. Can someone help me find a CHEAP product online that will allow for this?

Or maybe I should use epoxy? (would that come out really hard and plastic-like when it dries?)

Also can someone point out the pros and cons of using this method? Will the epoxy increase the chances of the circuit overheating? Should I embed heat syncs against the mosfets and leds or what?


An example of this occurring is in this instructable:
https://www.instructables.com/id/Power-LED-s---simplest-light-with-constant-current/step9/permanant-ize-it/

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standard sealant isn't suitable for potting electronics, which is why the real thing is so expensive. Standard sealant uses an "Acetoxy" cure - which liberates free acid in the rubber as part of the curing action....which corrodes your parts....

Potting rubbers use a platinum catalyst in a two pack formulation and DON'T attack the parts. They also tend to be very low modulus rubbers, so parts don't get strained.

Steve
SpiffyChee (author)  steveastrouk6 years ago
thanks for the tip! Do you know what brand makes some? and where I can buy it online?
That depends where you are in the world.

Steve
SpiffyChee (author)  steveastrouk6 years ago
USA. Washington State (seattle)
My UK supplier isn't going to be much use to you then !
AndyGadget6 years ago
You can get silicone sealant from ant DIY shop - It's used for sealing around the edge of baths, sinks etc. Look in the plumbing department.

Epoxy will be a better bet as it keeps things rigidly in place and is more heat resistant, and you can drill it to attach it to the case.

On the circuit you show, R3 and the MOSFET are going to get hot so don't embed these and use a decent heatsink, which needs to get some airflow across it.
I haven't done the sums, but 'finger in the air' tells me that the circuit in the Instructable is going to FRY if he draws any decent current from it as he has no cooling.