Abstract: A method of making a flexible circuit member including a stainless steel base member, a dielectric layer (polyimide) on the base member and a conductive circuit (copper) on the dielectric. The circuit member may be first formed as a laminate structure wherein the dielectric polyimide is coated on the stainless steel and appropriately treated (cured). The copper circuitry is then formed utilizing resist application and exposure techniques. Significantly, the copper-containing circuitry and stainless steel base member are simultaneously etched using a cupric chloride etchant solution to effectively remove desired portions of these metallic materials and produce the desired flexible circuit member.

Abstract: A method is disclosed for making circuitized, flexible film substrates in a continuous tape format using a transfer technique. The tape is made with window-like openings having a relatively thin layer of polyimide spanning the openings. The relatively thin layer of polyimide is transferred to the tape from a metal carrier foil, preferably by using a special adhesive system. After the polyimide is transferred to the tape, the polyimide spanning the window-like openings in the tape is circuitized to form individual, circuitized, flexible film substrates which may be handled in the tape format for further processing. Preferably, the tape includes perforations for engaging sprockets of automated manufacturing equipment, or the like.