Hi gang - I had the same first impression as Dick that these were solder
splatters from reflow/wave/stencil but when I looked closer, it the
splatters are very very uniform in size plus the center "dot' is equally
uniform. Someone had mention a filled micro via delamin-ish problem could
be the root cause. Take a look at the photo again - doesn't it seem that
these are too uniform for a solder splatter root cause?

Dave Hillman
Rockwell Collins
[log in to unmask]


On Tue, Jul 29, 2014 at 11:30 AM, Richard Krug <[log in to unmask]> wrote:

> To me it looks like solder paste spatter / fines that landed on ENIG
> surface.  Can be caused by too steep a ramp rate during preheat stage of
> reflow profile.  Was measured reflow profile within manufacturer's spec?
>
> Dick Krug, CSSBB, CSMTPE
> Lead Process Engineer
> Sparton Brooksville, LLC
> 30167 Power Line Road
> Brooksville, FL  34602-8299
> p (352) 540-4012  (Internal Ext. 2012)
> [log in to unmask]
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of John Foster
> Sent: Tuesday, July 29, 2014 12:13 PM
> To: [log in to unmask]
> Subject: [TN] Trying to figure out possible mechanism for contamination
>
> We have been seeing a problem recently on several different CCA'S that we
> are having assembled.
> The boards are ENIG with plug and plate.  The assembly shop is assuring us
> that these gold areas are being Protected during the entire assembly
> process with kapton tape.
> I was thinking it was flux splatter since the areas are always almost
> perfectly circular.
> The locations are very random and range from nothing to what is in the
> picture.
> Is there any other mechanism that might be causing this? On our next run I
> am going to go to the shop To witness the taping. But I was curious if
> maybe it's some other cause.
> Mr. Gregory was kind enough to post a picture.
> http://stevezeva.homestead.com/spots.jpg
>
> Any thoughts would be appreciated
> Thank You
> John Foster
> L3 Communicatons
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