A FLEXIBLE CIRCUIT AND A METHOD OF PRODUCING THE SAME

摘要

A structure comprising a flexible dielectric film supporting on at least one side a thermoplastic polyimide layer, and on it a conductive layer, is treated by an "semi- additive" process. The "semi-additive" process comprises forming a patterned photo¬ resist layer, filling gaps in the photo-resist layer with conductive material, removing the photo-resist and exposed portions of the laminated conductive layer, and covering the structure with a coverlay. The inventors have realized that the process of laminating the copper layer onto the thermoplastic polyimide layer roughens the surface of the thermoplastic polyimide layer, thus anchoring the copper layer to the polyimide, which means that when the conductive material is deposited into the gaps in the photo-resist, conductive bodies are formed which are strongly anchored to the thermoplastic polyimide layer, and which can be used as electrodes of a flexible circuit.