You would need to do SEM EDX on one of the black spikes to determine its
composition.  That would go a long way in determining what the problem was.

I note that they are all near a through hole.  I suspect you had a
contaminant or processing fluid trapped in those holes that bled out,
contributing to the problem.


Doug Pauls
Principal Materials and Process Engineer
Rockwell Collins

On Thu, Mar 17, 2016 at 3:58 PM, Technet Legg <[log in to unmask]> wrote:

> There are two board images of a conformally coated Engine Control Unit at:
>
>
> https://www.flickr.com/photos/128859641@N02/25836586336/in/dateposted-public/
>
> Not the best images, but would anyone care to speculate on the composition
> of the star-burst patterns circled there?
>
> Base on an even fuzzier image, I'd speculated that it was dye
> concentration in
> an uneven curing process, but these give it a colour that suggests external
> contamination of some kind, possibly bleeding into cracks.
>
> The spikiness suggests a dendrite growth, but I don't want to get anyone
> excited.
>
> RL
>


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