If they were filled with CB100 by DuPont, that material consumes the copper if they go through an extended cycle reflow, rework, or Pb-free processing.  It was among the first via fills out there, and for some reason is still specified occasionally.

Wayne

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dwight Mattix
Sent: Monday, September 17, 2012 1:09 PM
To: [log in to unmask]
Subject: Re: [TN] Broken Vias

start with x-section to see what basic failure mode is and look for latent mfg defects first.

At 10:02 AM 9/17/2012, Julie Silk wrote:
>Where's Paul Reid?  He made a comment in a seminar that he sees a
>higher failure rate for filled/plated over vias than for open ones.  I
>agree that your exact fill material and characteristics are needed.
>While this process is well-known, the fill and the wrap are significant
>variables.  Good selection for the fill, good process control for the
>wrap.  And look at what heat has been applied.  Any rework?  For these
>parts or nearby?


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