Abstract: An apparatus for laminating multilayered printed circuit boards while radically reducing the volume of inert gas that must otherwise be used to effect the lamination process. The invention employs a novel ring assembly, each such assembly disposed on a moveable, horizontally disposed shelf. Each such ring assembly comprises a hollow circular cylinder, the interior of which is adapted to radially enclose a multiple layer circuit module mounted on a heating platen. The axial surfaces of the cylinder are capped by a pair of seal plates and O-rings to form a gas-tight laminating chamber. Each shelf is adapted to travel vertically along a pair of support tubes whereby the entire array of shelves may be compressed relative to the respective shelves by a hydraulic or pneumatic cylinder the rod of which is affixed to the bottom surface of the lowermost shelf.

Abstract: 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.