Photoimageable permanent resist

Claim 1

A process for applying a permanent, photodefined coating on a substrate, the process comprising: a. providing a photodefinable polymeric composition composed of a free radical photoinitiator, a monomer capable of being polymerized by action of the photoinitiator, said monomer having a viscosity greater than about 1 kPa-s or being a solid at room temperature, a resinous compound, selected from solid, resinous compounds having epoxide and acidic functional groups, the epoxide functionality of the resinous compound being greater than 2, and the acid number being greater than about 15 and less than 60, the photodefinable polymeric solution being dispersed in a solvent to form a fluid coating composition; b. coating the substrate with the fluid coating composition; c. drying the fluid coating composition providing a dried, photodefinable coating on the substrate; d. exposing at least part of the photodefineable coating to ultraviolet light while protecting the rest from the ultraviolet light, the energy of the ultraviolet light being sufficient to activate the photoinitiator and polymerize the monomer in the coating and render the exposed portion of the coating insoluble; e. subsequently contacting the coating with an aqueous, alkaline, developing solution, in an amount and for a time sufficient to dissolve away the portions of the photodefinable coating which had been protected from the ultraviolet light, leaving a photodefined coating on the substrate; f. thermally crosslinking the resinous compound by reacting the epoxide functional groups, forming the permanent, photodefined coating.