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Published on Jun 1, 2017
I designed this PCB to use for tests with using the dry film photoresist that is widely sold on eBay. I've never had much luck with it in the past, but was trying it with a technique where it is applied onto a film of moisture to help it slide and allow full removal of bubbles and ripples. I'll be doing some more tests with it, especially as it provided very good results with wide margins of exposure, developing and etching. I also tried sodium persulfate as an etchant, but was not impressed. It's nice that it's clear, but it is slow and has a short shelf life as opposed to the traditional ferric chloride etchant which has near enough unlimited shelf life. The design itself started off as a cluster of LEDs with two rows of resistors, but then I decided to put the resistors in a circle round the LED connections, and then added the channel name in an arc round the board too.