초록 ▼

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 s

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.

대표청구항 ▼

An improved process for desmearing and etching the drilled apertures of a multilayered printed circuit board, the board of the type having a plurality of laminated layers, the process of the type that employs an evacuatable chamber having at least one pair of electrode plates for generating a plasma

An improved process for desmearing and etching the drilled apertures of a multilayered printed circuit board, the board of the type having a plurality of laminated layers, the process of the type that employs an evacuatable chamber having at least one pair of electrode plates for generating a plasma field therebetween; the improvement comprising the steps of: providing a pair of metal shields, each such shield being substantially identical in configuration to said circuit board and being substantially identical in aperture pattern to said circuit board, securing said shields to opposite surfaces of said printed circuit board in substantially congruent relation thereto, subjecting said shields and circuit board to plasma desmear and etching within said plasma chamber for a selected period of time, and removing said shields from said printed circuit board upon the withdrawal of said shields and circuit board from said plasma chamber.