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.