Lyle
     
     We experienced the same problem with polyimide. We added copper pads 
     around the NPTH drill diameter OR Drill NPTH while copper is still on 
     the board prior to etch. This eliminates the haloing.
     
     Roxanne Tovey


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Subject: FAB:haloing
Author:  [log in to unmask] at esdigate
Date:    6/6/96 8:20 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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