“Photo ablation of Dupont Kapton at energy densities in excess of 5J/sq.cm.” Available to Purchase

With the requirements on the multi-substrate technology involving smaller diameter vias through thicker layers of dielectric, the aspect ratio (thickness/diameter) of vias has been increasing from a range of 0.067 to 0.13 to a higher range of 0.833 to 1.25. This paper reports on the preliminary investigation in an on-going series of experiments to study the etching of these higher aspect ratio vias with fluences between 5J/cm² to 15J/cm². Two different optical systems were used, a 10X system consisting of a singlet lens, and a 10X system containing a defraction limited 10X multi-element lens. Etch rates were estimated and wall angle given.