which will not adversely effect the via formation but it is not clear where the limitation of vias per second will be with focus and power adjusts on the fly regardless the present invention avoids these limitations effective laser drilled blind vias can be made on the fly down to levels four five and six using the present invention the current limitation is not the effectiveness of the laser energy source to vaporize polymer dielectric but the inability to reliably electroplate high aspect ratio laser drilled blind vias an early form of laser drilling of blind vias is described in applicant 39 s prior u s pat no 4 642 160 the described method and systems then available were insertable for laser drilling at multiple depths drilling on the fly using a single pulse per via this invention carries forward additional process improvements primarily through the invention of a laser drilling system allowing the method described to cost effectively be fabricated on a production basis fig4 depicts a long focal length lens 17 ranging from 127 mm to 254 mm when focused between 2 54 mm to about 50 mm below the top surface of the circuit board etched window 22 changes the gaussian curve for the beam creating a broad watt density curve 23 as shown in fig5 the amount of energy that is allowed to enter the etched window is controlled by pulse duration pulse duration rates between 800 microseconds and 2 500 microseconds depend on the volume of dielectric material to be vaporized with a 200 watt sealed rf controlled co2 laser with the ability to pulse at 10 000 per second at zero duty cycle can deliver between 1 250 vias per second and 400 vias per second a 700.