What percent ratio of the foil is the nailheading?  The chipload for 
     the 0.0135 may be aggressive.  How do the drill bits look after use?  
     Are non-functional pads present?  For the smaller hole sizes, 14 to 26 
     ounces of copper per hole is a lot to ask for from a drill.  
     
     How is the cure on the material?
     What kind of backup and entry material?
     Drilling machine Type?
     Stack Height for the 104 mil material is 2 high?
     
     
     


______________________________ Reply Separator _________________________________
Subject: Random Nailheading
Author:  [log in to unmask] at corp
Date:    4/26/96 1:10 PM


     Problem:
     Random Nailheading within a X-section with layer-to-layer variations 
     (example: Layer 5 good, layer 6: left side bad, right side good...) 
     Also some half-nailheading (into B-stage side, but not C-stage side).  
     No resin smear or post-sep detected.  Bits used are new & 1st repoints 
     only with 1500 hits max (Tycom).
     
     Product: 8-12 layers, stack height 2, thickness 62-104 mils, FR4
     
     Typical Parameters:
     .0135" dia, 100krpm, 111 ipm infeed, 800 retract 
     .033"  dia, 66.6krpm, 173 ipm infeed, 800 retract
     
     Any advice would be appreciated.