Covering Maxflex in sealant??

[piesoup]

Hello everyone
Can I cover a MaxFlex3 in sealant providing there is a good thermal path from the gold area (to the alu body of the light) and a small heatsink on U1?
I'll be using an aircraft grade sealant called PR1428B1/2. I havent got a clue what the civillian version is! Running 4 XR-E R2s @ 1200mA from a 11.1v Li-Ion battery. Max input current from the battery will be 2.3A with 1.43W loss.
Thanks for any suggestions
Andrew

 

[hootsmon]

Well I'm no expert, but as I understand it, George doesn't particularly recommend potting the maxFlex drivers. From memory, he says the switcher IC runs at a high enough frequency that you'd need to be aware of capacitance issues, with whatever medium you're potting it in.

Out of curiousity; what's the rationale for covering a MaxFlex in sealant anyway? My *guess* is silicone sealant is probably a poor conductor of heat, so the other possible reasoning might be weatherproofing perhaps?

One more thought; dunno about your MIL-spec sealant, but I think common-or-garden silicone releases a lot of acetic acid when it cures, which would spell disaster for any electronics bits potted in it.

Anyway, to sum up I don't think sealant is a great idea; Instead, I'm planning to use a generous squeeze of Arctic Alumina adhesive, to pot the gold-pad side only.

Finally, you could try posting your question on the Forum at TaskLED.com.
You often get prompt answers to TaskLED technical questions over there.