Testing the photo resist by itself might be interesting but what really needs to be done is to test the system. Add your artwork and any hold down glass or vacuum frame and then run an exposure test with the step gauge over real PCB traces. At the wedge's dark end the board will be way underexposed and the resist will just wash away. At the other end, the UV will blast through even your "black" traces and when etching you will get solid copper without traces. In-between those two extremes you will hopefully have a good section if the artwork is good enough. Bertho [Non-text portions of this message have been removed]
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RE: [Homebrew_PCBs] UV LED box
2008-06-20 by Bertho Boman