Photoresist is shipped with a clear protective covering film on the top and bottom. The covering film is removed by the user before the photoresist is applied. A comment by a poster in a forum says the top covering should be kept on during exposure and removed before developing. Is that true? Why is that?
"Note that the dry film resist should be exposed with the cover sheets on, and then held in a dark place for 15 minutes before removing the cover sheets and developing."
http://www.electro-tech-online.com/general-electronics-chat/14427-photoresist-pcb-etching-process.htmlJeff