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After etching a PCB I discovered a big spot across some of the traces - probably from a finger. I transferred the PCB layout from a transparent film.

What would be the best way to remove "finger" and others from both the PCB and the film before etching without destroying them?

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We wash with a mild detergent and then put the PCB through a very quick bath in etchant.

After this point, we use gloves. The gloves are an attempt to keep our body oils off of the board. The board is very clean and nice for the photo-resist at this point, and it has paid off well.

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I would say it is impossible and you just need to expose a new board or try to fix the old one after etching. I'd just try etching the board and then just scraping the traces off from each other with a dremel or some other tool, depending where the fingerprint is.

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  • \$\begingroup\$ Yeah, my answer is geared towards future boards, the current one is probably easier to cut the traces yourself. \$\endgroup\$ – Kortuk Nov 23 '09 at 19:57
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Make sure you have the transparency in direct contact with your photosensitive board. Any distance between them will cause distortions. Similarily, you will want a glass plate on top of the transparency to keep it flat. Remember, your etching will only be as good as the artwork.

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We have had a lot of luck subsituting regular white paper stock for the transparency. We have found that the process ends up with less broken tracees and "blob" spots. You have to increase the exposure time for the time under the UV light. This only works for photo-etching.

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Tracing paper in a laser printer is better than film you get better toner adhesion. Use the thick stuff >=90gsm to avoid crinkling in the fuser.

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