Abstract

A method of making circuit boards is disclosed that is suitable for use in a high-volume automated processing plant. The method can be used to produce either single-sided or double-sided circuit boards with access windows allowing electrical access and connection between traces from both sides. In the process, access holes are punched in a coverfilm. A copper sheet having a tin plating on one side is laminated to the coverfilm, with the tin side facing the coverfilm. A pattern representing a circuit is screened on the resulting laminate with a UV-curable resist, developed in a UV dryer, and then the unprotected copper is etched away. The remaining tin is then removed with solder stripping agent, and the resulting circuit is protected with a coverfilm. The process can be applied to large rolls of materials in an automated process, with large numbers of circuits applied to the laminated board. The circuits can then be punched out of the web with a hydraulic press in large numbers. The use of two copper sheets and double-sided covering (i.e., having adhesive on both sides) in a slightly modified process permits the efficient manufacture of double-sided circuit boards.