LASER THROUGH-HOLE DRILLING AND LASER CUTTING IN TEFLON

We report a novel technique for laser highspeed drilling and cutting i n teflon films. The new laser drilling surpasses the conventional tech niques in simplicity, throughput and spatial resolution. The laser cut ting and drilling process consists of three simple steps. First, a thi n absorbing layer (in this case 300 Angstrom of gold) is deposited on the teflon to allow for laser absorption. Second, the drilling is perf ormed by pulsed-laser irradiation at the rate of one hole per pulse. T he irradiation process does not completely open the holes in which deb ris still remain. Third, the ultrasonic cleaning in water is used to r emove the modified and weakly bound material inside the drilled holes, leaving behind 50 mu m diameter through holes in 25 mu m thick teflon sheets. The drilling process-window is well mapped. The cutting proce ss is obtained by fast scanning the laser beam at laser powers above a threshold value. This new technique is desirable for packaging becaus e of its drilling speed as high as 60 000 holes per minute, its fast c utting and its low laser equipment cost.