The applicability of electrodeposited photoresists in producing ultra‐fine lines using sputtered seeding layers

Photolithographic techniques are universally employed in multi‐layer printed circuit board manufacturing. The growing demand for miniaturization of electronics means that finer lines and smaller vias are increasingly required and these very fine lines on the substrate are increasingly difficult to produce by conventional means. One very promising means of meeting these fine line requirements is via the etching of sputtered thin films on a substrate and then growing copper on these lines using an additive method. In this work we tested the capability of an electrodeposited, positive‐acting photoresist for patterning thin film circuits on sputtered seed layers such as chromium. A fully additive electroless copper was then used to produce the copper lines. Epoxy reinforced fibreglass was used as a core material. The performance and quality properties of the process were examined, along with limitations of the process when compared with both a conventional dry film method and a spin coating method.