Laser micro drilling of around 3 microns into Ajinomoto Build-up Film

As the electrode spacing of the chip decreases, the diameter of the via holes in the redistribution layer or build-up substrate must also decrease. Here, we have demonstrated a via hole creation with a diameter of 3 microns on Ajinomoto Build-up Film (ABF) by irradiation of a picosecond, 266-nm wavelength laser. A copper wiring pattern was created on a glass substrate, and 3-micorometer-thick ABF was attached on top of the pattern, which was used as a model substrate.