Hole taper control in femtosecond pulsed laser drilling of silicon carbide ceramic

Abstract Femtosecond pulsed laser drilling of silicon carbide (SiC) ceramic was performed to investigate effects of spiral scanning turns on hole taper control. Experimental results indicated that positive cone, cylinder and negative cone could be processed by adjusting spiral scanning turns. Although hole taper presented a decreasing trend as spiral scanning turns increased, it increased slightly at the condition of more dense paths. The changes of laser energy, debris and plasma caused by the change of spiral scanning turns were analyzed. It was worth mentioning that more spiral scanning turns meant longer drilling time, which would not only prolong the interaction between laser and materials, but also reduce the efficiency of laser drilling. On the premise of meeting the hole taper requirements, less spiral scanning turns were the preferred processing parameters. Differences of microstructure and elemental contents at hole wall were analyzed and discussed. Results indicated that contents of Si and O were higher, content of C was lower near the exit than that near the entrance.