EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: Jebnor on July 12, 2013, 05:43:33 pm
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Does anyone have a PCB Etching test pattern for a 4x6, or smaller, board? I have had to buy a new UV Lamp and I'd like to test it before I etch 'real' boards.
Ideally, I'll have 4-6 of the same pattern on a 4x6" board. I'll then bracket the expected exposure time to see which turns out best. If I can't find one, I'll make one. It will probably just have positive and negative trace widths and a couple of drill pad diameters. When building my own boards I just leave a 16mil center for the pads and vary the outer diameter to the required size. This allows me to use whatever drill size is appropriate and if I miss a little, I don't have non-copper next to the hole. If I end up making one, I'll post it.
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Why not use some free download PCB generating software and make your own in a few minutes?
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I have made one in the past for exactly this purpose (calibrating exposure time for my UV source).
I'll try to find whether I still have it when I get back to my computer in a bit...
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This seemed like a good reason to fire up eagle and see if I could still use it, I'm not sure if this is what you had in mind or not:
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Found it, here it is. Eagle format (5.x I think, it's been a while). Don't forget to run Ratsnest before printing it.
Its very simple. Cover it all, leave just the section 10 exposed. Turn on the UV light, and every time interval (I used 1 minute at the time, my UV source was not very strong) uncover another section.
When you develop the board, low numbers will be underexposed, high will be overexposed, and somewhere in between there will be your sweet spot ;) Turned out to be about 4 minutes for me at the time (UV lightbulb for dark light, not very ideal, too short wavelength). With my new UV LED based source it would be more like 10 second intervals.