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IP.com Disclosure Number: IPCOM000024985D
Original Publication Date: 1983-Apr-30
Included in the Prior Art Database: 2004-Apr-04

Publishing Venue

Xerox Disclosure Journal


Photolithographic techniques are used to fabricate most integrated circuit chips as well as less complicated and exact circuit boards. To perform this function, a phototool comprising an opaque pattern on a clear field is used to contact expose, proximity expose or projection image expose the details on a photosensitive material. The latent image on the photosensitive material is then developed and the pattern formed by chemical milling, plating or other techniques to form the desired structure. To produce a single-sided circuit board, a photosensitive material is applied to a copper clad glass filled epoxy board and a latent image formed by contact exposure through a phototool. The photosensitive material is developed leaving the desired pattern in the form of an etch mask. The copper in the unprotected area is then removed by etching through this etch mask. The etch mask is then stripped, leaving a circuit board with the desired copper runs. The most difficult part of this process is the manufacture of the phototool. This has been traditionally done by using photographic techniques which require sophisti-cated equipment. First, the pattern is generated by either manually cutting the pattern or composing this pattern on a material of opposite contrast. The pattern is then photographically copied or reduced to form a mask. The mask is used to contact print the phototool by a traditional photographic emulsion on either glass or polyester, or a more sophisticated chrome on glass.