September 12, 2004

We think root cause is poor PTH copper plating process control which allowed excessive build up of the copper.  Subsequent abrasion of the tin/lead plating over the copper with scotch brite allowed slivers of tin/lead/copper to flake off and become randomly dispersed over the surface of the PWB.  The ionic contamination test done just prior to solder mask did not detesct these slivers, and I would not expect it to..  Unfortunately the pre-solder mask coating did not remove these.  Attached is picture of one of the MIL-P-55110 test coupons which shows excessive copper plating bulidup.
  ----- Original Message ----- 
  From: Susan Mansilla<mailto:[log in to unmask]> 
  To: [log in to unmask]<mailto:[log in to unmask]> 
  Sent: Friday, September 10, 2004 9:01 PM
  Subject: Re: [TN] PWB Conductive Contamination Under Solder Mask; What Can Cause ...


  Since Jeff volunteered me, I would be happy to take a look and post photos so
  we can all see this phenomena that has all of us puzzling.

  Susan Mansilla
  Robisan Lab

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