Method of producing fine-line circuit boards using chemical polishing

Abstract

A printed circuit board is produced by patterning a resist layer according to a circuit mask that defines desired circuit paths. The resist pattern layer is formed by removing the resist from the board in the desired circuit paths and a conductive material is plated onto the board in the resist voids defined by the circuit mask so that the height of the conductive material relative to the substrate equals or exceeds the height of the resist layer relative to the substrate. A low-reactive solution is applied over the conductive material and removes a surface portion of the conductive material. As the solution removes the conductive layer, it forms a film barrier and the solution composition changes, both of which substantially inhibits any further removal of the conductive material. Next, the film barrier is removed from the board allowing another film barrier to form stimulating the removal of further conductive material. The removal step is repeated until the conductive material is at a desired height relative to the height of the resist layer. The board is then finished using conventional circuit board fabrication techniques.