Process for plasma desmear etching of printed circuit boards and apparatus used therein

摘要

The inconsistent etch-back characteristics of conventional plasma treatment of multilayered printed circuit boards, are overcome by use of a shield, preferably of aluminum, temporarily affixed to each surface of the circuit board during the plasma desmear and etch process. The shield is sufficient size to overlap virtually the entire circuit board and contains an aperture pattern which is substantially congruent with the aperture pattern of the circuit board. The shield affects the plasma process, rendering the etch-back effect substantially homogeneous and consistent throughout the circuit board irrespective of the location of each etched aperture on the circuit board. Alternative embodiments include a wire mesh which obviates the congruent hole pattern requirement and use of a low D.C. bias voltage to further regulate and control the plasma effect.