If the "Spots" are vias they would not be on a grid. You can see what appears as large capped stitching vias on a grid but it is a fairly large grid.
Bob K.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Tuesday, July 29, 2014 4:16 PM
To: [log in to unmask]
Subject: Re: [TN] Trying to figure out possible mechanism for contamination
Wow, if they are microvias on a grid pattern, that would be the first time I've ever seen that. I can't even wrap my head around how many holes that board would have!
Steve
On Tue, Jul 29, 2014 at 1:50 PM, Stadem, Richard D. < [log in to unmask]> wrote:
> Yes, they do look like microvias. Plugged during fabrication and blown
> open by the reflow process.
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Kondner
> Sent: Tuesday, July 29, 2014 2:31 PM
> To: [log in to unmask]
> Subject: Re: [TN] Trying to figure out possible mechanism for
> contamination
>
> I still think they look a lot like vias but some would have to be
> micro vias.
>
> Yes, the consistent "Roundness" sure looks like via clearance etch back.
>
> But it is SO SIMPLE - Are there holes? :-)
>
> Bob K.
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of David Hillman
> Sent: Tuesday, July 29, 2014 3:21 PM
> To: [log in to unmask]
> Subject: Re: [TN] Trying to figure out possible mechanism for
> contamination
>
> 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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