Patent ID: 9622353
Date: 2017-04-11
CPC Classifications: G03F,H05K

Claim:
1. A method comprising: a. providing a substrate comprising raised traces, and one or more apertures selected from the group consisting of through-holes and vias; b. applying an aqueous alkaline soluble UV photosensitive material adjacent a surface of the substrate comprising the one or more apertures and the raised traces to provide an unplanarized surface on the aqueous alkaline soluble UV photosensitive material; c. applying a flexible aqueous soluble UV transparent film adjacent the aqueous alkaline soluble UV photosensitive material with the unplanarized surface to planarize the surface, wherein the flexible aqueous soluble UV transparent film is selected from the group consisting of aqueous soluble polyvinyl alcohols, water soluble cellulose ethers, water soluble carboxyalkylcellulose ethers, water soluble salts of carboxyalkylcellulose, water soluble salts of carboxyalkyl starch, water soluble polyvinyl pyrrolidone, water soluble polyacrylamides, water soluble salts of polyacrylic acid, gelatin and ethylene oxide polymers; d. selectively applying an aqueous alkaline strippable UV blocking composition adjacent the flexible aqueous soluble UV transparent film; e. exposing the aqueous alkaline soluble UV photosensitive material with the planarized surface to UV radiation except in regions covered with the aqueous alkaline strippable UV blocking composition; and f. simultaneously removing the aqueous alkaline strippable UV blocking composition, the flexible aqueous soluble UV transparent film and selective portions of the aqueous alkaline soluble UV photosensitive material with the planarized surface with an aqueous alkaline solution.