Abstract
In order to use the excimer laser ablation in the practical application of flexible printed circuit board production, a high-speed excimer laser micro-drilling apparatus has been developed. The apparatus has two significant technical points: (1) the increased energy efficiency of the optical system which is named Multiple Irradiation Optical System (MIOS), (2) the synchronous scanning system that enables large area processing. Newly developed MIOS with a spherical concave mirror is more stable than the MIOS with a flat mirror. The energy efficiency of the MIOS is high even for large mask openings.
The apparatus has been applied for drilling of via-holes of the size less than 20 microns. The processing time is about one minute for a polyimid film 100mm × 100mm wide and 25 microns thick.
