Potting boards...

(repost with [EE] tag.  sorry.)



Hello all, I have a client who wants to pot the board I'm making to make
it as indestructible as possible.

I haven't done this before, and wonder a few things.
Maybe someone would like to offer advice?

Heat.  The components being potted generate some heat, not a lot, and
there will be a heatsink of some sort on the underside of the board.
(only the top is being potted).  So I'm not too worried about this.

My main concern is what being potted may do the following component types:

Electrolytic caps: they have some sort of safety vent, right?  If
sealed, and should disaster occur somehow, I figure failing in potting
couldn't be any worse than failing in open air?

Inductors: I'm using 5 for dc/dcs, 4 of which handle significant current
(2amps) in pulses.  They get pretty warm.  I just wonder if the potting
compound could cause them to change behavior (inductance value, current
capacity) in a significant way, by possibly squeezing them a little when
it cures?  Seems unlikely, thought I'd ponder.

Crystal: there is a 10mhz xtal that needs to be reasonably accurate
(250K baud serial coming in), and I remember somebody here saying once
how potting a board made their xtal drift.  How problematic might this be?

Any advice appreciated.

Thanks all-
J




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