The problem of Blurry PCBs
I have a new UV exposure unit with tubes on both sides to avoid flipping the PCB when making a double sided one.
I have tried different exposure times, but the final results come out all blurry. The toner of the film is placed against the bare PCB to avoid light from the sides and reflective film in the bottom of the unit creates a uniform light exposure.
Have anyone met this problem before and know the cause of this?
I have been using the photo method since the late 1990's and have never had that problem. Did have some bad resist once, but that manifested itself as flaking of the resist.
I am happy that you shared this helpful information with us.