Photosensitive hybrid polysilsesquioxanes for etching-free processing of flexible copper clad laminate

Abstract A photosensitive ladder-structured polysilsesquioxane was synthesized for the development of flexible copper clad laminates through electroless plating of Cu. The developed ladder-structured polysilsesquioxane with controlled structure enabled easy introduction of protected thiol and allyl functional group, which under acidic conditions, the thiol group becomes deprotected. This deprotected thiol group enables UV-initiated thiol-ene curing of the exposed regions, while the unexposed regions containing free thiol groups act as seed initiators for Cu electroless plating, and the corresponding negative pattern fabrication process also possible. Through this facile method, we were able to develop flexible copper clad laminates of tunable Cu interconnect width size of high electrical conductivity according to photomask pattern and the insulating dielectric surrounding layer exhibiting low dielectric constant and low loss behavior without any corrosive Cu etching steps.