UV laser micromachining for the electronics industry

Abstract

Ultraviolet laser micromachining has increasingly been applied to the electronics industry where precision machining of high-density, multi-layer, and multi-material components is in a strong demand. Due to the ever-decreasing size of electronic products such as cellular phones, MP3 players, digital cameras, etc., flexible printed circuit board (FPCB), multi-layered with polymers and metals, tends to be thicker. In present, multi-layered FPCBs are being mechanically cut with a punching die. The mechanical cutting of FPCBs causes such defects as burr on layer edges, cracks in terminals, delamination and chipping of layers. We have used a UV nanosecond laser and a picosecond laser (355 and 532 nm) to cut FPCBs in order to examine the applicability of laser and to compare the cut quality. Hydrophobic surface can be easily cleaned, due to the self-cleaning effect which can help keep hand-held mobile devices cleaner. With a UV picosecond laser, we have directly engraved 10-micron hydrophobic conical patterns on the surface of a mold metal, NAK80. The contact angle of a PDMS replica increased from 90° to 157° We also have directly fabricated a diffraction grating mold using NAK80 for cell phones. It has 2-micron line patterns. Wafer drilling for multi-chip packaging requires via hole diameters of several tens of microns. As an attempt to reduce time and cost, more and more electronic device manufacturers rely on UV laser drilling of through via holes. Using a UV laser, we drilled through via holes in silicon having a sub-15-micron diameter.Ultraviolet laser micromachining has increasingly been applied to the electronics industry where precision machining of high-density, multi-layer, and multi-material components is in a strong demand. Due to the ever-decreasing size of electronic products such as cellular phones, MP3 players, digital cameras, etc., flexible printed circuit board (FPCB), multi-layered with polymers and metals, tends to be thicker. In present, multi-layered FPCBs are being mechanically cut with a punching die. The mechanical cutting of FPCBs causes such defects as burr on layer edges, cracks in terminals, delamination and chipping of layers. We have used a UV nanosecond laser and a picosecond laser (355 and 532 nm) to cut FPCBs in order to examine the applicability of laser and to compare the cut quality. Hydrophobic surface can be easily cleaned, due to the self-cleaning effect which can help keep hand-held mobile devices cleaner. With a UV picosecond laser, we have directly engraved 10-micron hydrophobic conical patterns o...