| 摘要 |
1493834 Photographic processes for making printed circuits SHIPLEY CO Inc 23 Oct 1974 [25 Oct 1973] 30114/77 Divided out of 1493833 Heading G2C Printed circuits are made by imagewise exposing a material comprising a metal clad circuit board, a non-photo-sensitive intermediate layer on the metal cladding and a photo-resist layer, selectively developing with a first developer the photo-resist layer, developing the bared areas of the intermediate layer with a second developer and selectively etching the cladding. The exemplified photo-resist is a napthoquinone diazide and a novolak resin and the exemplified interlayer is a mixture of polyvinyl alcohol and melamine resin which has been cross-linked; the photo-resist being developed with alkali and the interlayer being developed with acid. There may be two interlayers, the top one of which may be developed by the developer for the photo-resist. Photo-sensitive polymers, polyvinyl azidophthalate or bichromated materials may also be used as the photo-resist. The interlayer and photo-resist layer may be applied to a temporary support and the interlayer then laminated to the metal deck board and the temporary support is removed. |
