Well Jack, sometimes the board edges are metallized so that it serves as a
grounding path and sometimes as a thermal conduction path.  In those cases,
the presence of conformal coating interferes with the function of the board
and so it should not be present.  That is usually the question I ask
designers all the time - will conformal coating in Location X interfere
with the form, fit or function of the unit.  If yes, then it is a keep out
zone.


Doug Pauls
Principal Materials and Process Engineer
Rockwell Collins

On Mon, Mar 5, 2018 at 10:00 AM, Jack Olson <[log in to unmask]> wrote:

> Typically the goal is to protect conductive surfaces, and board edges
> don't often have conductive surfaces (and if they do, they might need to
> stay exposed).
>
> If you have seen the board edges coated it is probably a result of the
> method that was used to coat them (spraying or dipping), not because it was
> required.
>
>
>
> On Thu, 1 Mar 2018 09:45:26 -0600, Caitlen Gahm <[log in to unmask]>
> wrote:
>
> >Greetings,
> >
> >We are wondering what the general thought is regarding whether or not the
> edge of a CCA/PWB needs to be conformally coated?  We received CCA's from a
> supplier and noticed that the edges were not coated.  Our thinking thus far
> is that since our drawing does not state that coating on the edge is
> optional or not required, it would be required.
> >
> >What we are curious to know is what the general consensus is regarding
> whether or not it is necessary to coat the edge of the CCA and instances
> when this would or would not be desired.
> >
> >Thank you,
> >Caitlen Gahm
> >Materials and Process Engineer
> >Crane Aerospace & Electronics
>