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October 1999

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From:
"Ingemar Hernefjord (EMW)" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 13 Oct 1999 11:09:21 +0200
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Hi Ron,
I'm also curious about 'Black Plague' because we see many kinds of boards passing all day long. I feel I have been misunderstanding the whole thing, because we use a similar expression for describing dewetted areas i.e. copper/nickel/gold pads where the gold was first alloyed with the Sn/Pb in milliseconds, followed by solder withdrawal, which leaves the nickelplating with solder remnants so thin that the pads appear blackish. Further analysis showed lead oxides and copper. Copper seemed to have diffused extremly rapid cross the surface from conductor sides. Fortunately, this happened so seldom that it became no big affair. So it's more than ten years since I heard anything.

Ingemar



Franklin
We are seeing the problem mainly at our wavesoldering operation.  We have
seen some, little, at the SMD workcell.  We have checked our wavesolder
process and profile and it has not changed.  The problem is lot number
dependent.  A specific date code may have multiple lot numbers, and the
issue show up on one lot number only and not every board in the lot.  Bare
board condition shows no early warning signs that we have detected at this
time.  We have cross sectioned some boards to see if there may be a tell
tale sign, but nothing outstanding.  We do have a couple boards in for that
cross sectioning at the present time.  No data back yet.

Ron

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