HADCO advocates the removal of what is referred to as non-functional pads. We have not really seen it add rigidity to the hole wall. The reason why we ask for them to be removed is because they may detach and "float" during the inner layer fabrication process, ending up causing a short which would have to be removed when detected during the AOI (Automated Optical Inspection) process. Another reason for advocating removal is because of an increase in layer counts. Take a 14 layer with 1 oz. cu. inners and 1/2 oz. outers. If every layer had a pad, that would equate to drilling through almost .018" of copper! The excessive wear and tear on the carbide drills might actually contribute to poorer hole wall quality without the proper checks in place. Less drill usage would also equate to a cost adder. I am unaware of any returns from our customers which could be attributed to removal of non-functional pads (inner layer pads with no incoming traces). I hope this helps. Tom Coyle Customer Services Engineer HADCO Corporation [log in to unmask]