VIA-HOLE DRILLING IN A PRINTED CIRCUIT BOARD USING A CARBON MONOXIDE LASER

摘要

Apparatus for drilling a via-hole in a printed circuit board (PCB) includes a carbon monoxide laser deliver laser radiation pulses. The pulses have a relatively broad wavelength-range, and slow rising and falling edges. The rising and falling edges of the pulses are clipped using and acousto-optic modulator. A dispersion-compensator compensates for dispersion in the clipped pulses introduced by the AOM. Achromatic focusing optics focus the dispersion-compensated, clipped pulses on the PCB for the via-hole drilling.

主权项

1. Apparatus for laser-drilling a work-piece, comprising:
a first acousto-optic modulator (AOM) a carbon monoxide (CO) laser emitting laser-radiation pulses with radiation in the pulses having a plurality of wavelengths in a wavelength range between about 4.5 micrometers and about 6.0 micrometers, the radiation pulses having a temporal rising edge and a temporal falling edge and the laser radiation pulses being incident on the AOM in an incidence direction; the AOM being arranged to receive the radiation pulses, disperse a central temporal portion of the pulses, excluding a portion of the rising edge and a portion of the falling edge, in a first range of wavelength-dependent dispersed directions at an angle to the incidence direction, and transmit residual portions of the pulses along the incidence direction; a dispersion-compensator arranged to receive the central temporal portion of the pulses and reduce the range of dispersed directions to a second range less than the first range; and at least one optical element arranged to achromatically focus the temporal pulse portions from the dispersion-compensator onto the work-piece.