Lyle,
     
        Is it FR-4 or Polyimide?  Polyimide is tough! Have you tried 2nd
     drilling before etch?  (If you try this, get out the white gloves 
     and make sure the panels don't get scratched from handling or pins
     on the drill machine.) Also, my 2 nd drill parameters are pretty
     hot and fast. Maybe wind it up a little.
     
     Groovy
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Subject: FAB:haloing
Author:  [log in to unmask] at SMTPLINK-HADCO
Date:    6/6/96 11:28 AM


We are 2nd stage drilling .220" to .250" holes at NC rout and experiencing 
.020" to .030" haloing/delamination. The 2nd drill is in areas of bare 
laminate (no metal pad or ground plane).  Does anyone have suggestions to 
prevent this? Thanks for any input.
     
Lyle Anderson
Electrostar-Utah
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