It took a few attempts, but I think I've got the hang of PCB etching
Posted Feb 10, 2013, 5:44 PM UTC
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As a friendly bit of OCD advice for perfectly flat cut edges on boards: score both sides with a box cutter or other super sharp knife using a hunk of metal like an old-school ruler as a guide. do several passes so there's a pretty deep void. Scoring/cutting the copper keeps it from peeling (i am impatient so i frequently don't score enough on one or both sides and the copper peels and the fiberglass edge looks aesthetically horrible.) snap it over a sharp edge like on a desk or countertop to get beautiful clean edges, useful for aligning future patterns/boards on the leftovers.
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I'm gonna have to do this next time, I've just been using a dremel to cut the boards up.
fiberglass residue all over the place is not nice.
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Wear a good particle mask. N or P 95 or p99 or 100 also eye protection!
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What UV reactive material are you using?
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Where can you buy that stuff? It doesn't seem like there are any non-corporate providers. --> I'm in the US. I'm assuming you are in the UK?
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I've always only used the toner transfer method. Would you recommend moving up to photoresist?
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I've read an article stating that while it has its benefits, adds much more error possibilities. With toner transfer, once you have your printer density settings figured out, only thing is the proper temperature. Now with UV, you can under/over expose. Then, UV lamps are getting weaker over time, so you must have a lot, lot of experience to take that into account. Also, equpiment cost. Everyone has a unused iron around. Even if not, you can get one for free / next to free. Now, UV PCBs are more expensive. Developer costs too. If you earn money on PCBs it can be somewhat ignored, but if you are a hobbyist (which I assume you are, making PCB yourself) this is quite an expense. Plus, the lamps, as mentioned above.
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hells yes. Toner transfer drove me nuts!!!!!!!!
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Now do it in a pitch fine enough for SMDs, and do it on both sides.
Edit: Curious, was this photo etching or the toner method?
Edit: I'm stupid, I see the transparencies.
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Those failures are shockingly bad, what happened there?! It looks like you took it out of the etch too soon.
I've used Press'n'Peel as well as ironing down laser printer toner from a sheet of plastic, always had good results.
Glad to see you're using SMD parts though.
Double-sided professional PCBs are so cheap these days, I don't think it's worth making it yourself unless you desperately need a PCB that night.
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Those failures are shockingly bad, what happened there?!
Well firstly bear in mind this is the first time I've ever done etching, so I was learning as I went along, and working with kit in an unknown state.
From the top;
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Underdeveloped. Instructions suggested no more than a minute, and my hackspace buddies assured me that three minutes was certainly too much already. It wasn't.
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Underexposed. I was using paper here, and badly underestimated how long it would take. These are at 2, 3 and 4 minutes of UV I think.
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(not shown) Bad contrast, susequently swapped to acetate.
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These are braketed exposures again, left ones are underexposed. Underdeveloped, overstripped, and PRP not very clean
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The actually good one.
The last one is also on heavier copper, which I think gives more margin for error.
Double-sided professional PCBs are so cheap these days, I don't think it's work making it yourself unless you desperately need a PCB that night.
A reasonable point, and I suspect in five or ten years no one will do this any longer. I certainly wouldn't bother were it not for the fact I have a proper etching station at my hackerspace.
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Some advice, use GND/VCC planes. This way you are only etching what isolates the pads and traces.
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Exactly. No reason to dump tons and tons of copper into your solution.
Also, you can generally get away with gloves + a brush to wipe away the copper quicker. Don't leave it in there too long, or it'll start eating away at the sides of thin traces and completely detach them.
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Aah, I see, bracketed exposures, that makes sense. I have never tried photoresist because it always sounded like a real pain to use and somewhat trial and error. Drawing on the resist or the transfer method made the most sense to me. Press'n'peel works really well.
I once tried silk screen printing emulsion on a PCB. So I printed the PCB on to some transparency, covered a PCB in emulsion, then exposed it using the silkscreen equipment at the university, then washed off the emulsion. It looked terrible!
I have a proper etching station at my hackerspace.
Damn, I've really gotta move to London! I'm near Nottingham, but I haven't checked out their hackerspace yet.
I also miss attending a regular Dorkbot. I was pretty active in the Sydney Dorkbot, but there's not much around here ...
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looks like you are improving! I spent this weekend doing my first etched pcb also :) good luck.
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Which etching solution do you use? I use cupric chloride and gotten amazing results, plus i feel like it etches so much faster, its also wayyy cheep.
http://www.instructables.com/id/Stop-using-Ferric-Chloride-etchant!--A-better-etc/
Yep, cupric chloride here too. It was giving off some fairly unpleasant fumes though - hydrogen chloride I presume. Heated bubble tank, so it took about 10 minutes on 1oz board.
THANK YOU! I clicked a link from your link that took me to MG Chemicals. Under further investigation, I found MG Chemicals offers an aerosol product with nickel flake, for use on plastic enclosures to shield EMI/RFI.
This is a solution to a problem we have been struggling with at work for MONTHS.
so again, THANK YOU.