The applicability of electrodeposited photoresist in producing ultra-fine lines using sputtered seeding layers

Photolithographic techniques are universally employed in the manufacturing of multilayer printed circuit-boards. Photoresist is one of the most complex materials used in circuit-board fabrication. Negative acting dry film type photoresists are mainly utilized in patterning, although liquid photoresist may be a good alternative. A uniform coating of the photoresist is critical because of variation in the thickness of the photoactive layer when spraying, or using roller-coating or dip-coating. When the photoresist system is based on an electrodeposition method, both the uniformity and thickness of the resist can be controlled. In this work, we tested the capability of electrodeposited, positive-acting photoresist thin film circuits on a sputtered seeding layer such as chromium. Full additive copper was used to produce copper lines. Epoxy reinforced fiberglass was used as a core material. The properties related to the quality of the process were examined, along with limitations of the process compared to a conventional dry film method and to a spin coating method.