We have had quite a bit of experience with excimer lasers.
They will ablate through polyimide without causing thermal
damage to the copper. However they are considerably slower than
CO2 or YAG lasers. Reckon to remove about 0.3 micron of material
per pulse. You will get 200 to 300 pulses per second from an
Exxcimer laser. Best bet is to speak to some manufacturers.









         Here are some UK phone numbers.

         Lumonics
         +44 1788 570321

         Exitech
         +441993 883324

         J Drake
         Celestica Ltd