Via-hole drilling in a printed circuit board using a carbon monoxide laser
AssigneeCoherent, Inc.
InventorsGongxue HUA, Eric R. MUELLER
Life of this patent
Estimating the term…
Abstract
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.
Claims16
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.
Apparatus for laser-drilling a work-piece, comprising:
- a first acousto-optic modulator (AOM) sequentially operated by at least first and second RF signals having the same frequency but different magnitude;
- 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 first and second central temporal portions of the pulses excluding a portion of the rising edge and a portion of the falling edge through application to the AOM of the first and second FR signals, with the first and second temporal portions being dispersed in a first range of wavelength-dependent dispersed directions at an angle to the incidence direction, the first and second magnitudes of the RF signals being selected such that the peak power of the first and second temporally adjacent central temporal portions is about equal;
- a dispersion-compensator arranged to receive the central temporal portions 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.
Dependencies are inferred from the claim text.