Mr. Tryzbiak,
   Sorry for the delay in this reply, but here are the answers you 
were looking for with regards to your drilling scenario.  We are the 
Pluritec representatives in the southeast, and have one of the best 
CNC service engineers on staff.  We also maintain a service center 
repairing spindles, servo motors, lead screws, etc.
   Your example was a 6 layer PCMCIA board with half ounce copper 
inside, 16 mils thick, with 20 mil pads.  Using a 10 mil drill bit, 
these are the responses to your inquiry:
     1. Drill height should be .020" above the entry material, with a 
feed rate of 70 ipm, spindle speed of 100k rpm
     2. No drill breakage should occur during one table load. 
Penetration into the back-up material will be the major factor for 
breakage.
     3. The ideal flute length should be .01" greater than the stack 
height + entry + back-up penetration
     4. The retract rate should definitely be lower, a good starting 
point would be 300-400 ipm.
     5. How far you drill into the back-up will depend on the 
flatness of the table. The minimum should be achieved, .010" would be 
sufficient.  If flatness varies by .005", this will need compensation 
by splitting the difference and over-penetrating.
     6. No specific brand of back-up or entry is needed, but a hard 
phenolic back-up and .007"-.010" aluminum entry should be used.
     7. Entry material is used and necessary for registration and 
wear properties.
     8. Drill wander or splay should be minimum if not almost 
undetectable. If drill wander is detected with a .008" or .010" drill 
bit, breakage will soon follow. A good guess for tolerance would be 
no more than .0003".

I hope this answers all your questions. If you need more specific 
information, do not hesitate to call me direct at Sun Coast Supply (1-
800-264-1250).

David Mander
Sun Coast Supply