Rapid laser drilling on thick ceramic substrates for SiP applications

Drilling of thick ceramic material by using ultraviolet (UV) laser has been carefully investigated in this paper. Ceramic materials are commonly used in packaging of special Integrated circuit (IC), such as power IC, System-in-Chip (SiP) …etc. For thermal and strength reasons, the ceramic substrates have to maintain certain thickness. Also the number of via holes can be huge. Laser is a fine tool for drilling ceramic materials, however, the process can be very time consuming under this circumstance. Another issue is the flushness of the side wall. For thick substrate, laser drilling tends to create tapered side wall due to optical absorption. The helical-like rotation of laser beam is modified to improve the taper angle 1∼3 degree. For a 1.2 mm thick AhO3 ceramic plate, total laser scribing time: 5.35 minutes; top dia.2.59∼2.61 mm; bottom dia. 2.35∼2.57 mm. A 20W UV laser was used in the study. A series of comprehensive parametric study has been conducted in this paper.