US Patent 7955783 Lamination for printed photomask

A method for masking regions of photoresist in the manufacture of a soldermask for printed circuit boards is disclosed. Following application of photoresist over patterned traces on a substrate, a sheet-like thin film is applied over the photosensitive material. The thin film may adhere to the photosensitive material by way of the adhesive state of the photosensitive material or by way of an adhesive applied to the photosensitive material or the thin film or carried by the thin film. Digital mask printing may proceed on the surface of the thin film. The photosensitive material may then be exposed through the printed photomask, the thin film (with photomask) removed, and the photosensitive material developed.