Author Topic: General Etching issue  (Read 1009 times)

Geetarded

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General Etching issue
« on: October 22, 2016, 10:03:21 PM »
Hi,

I am etching using HP gloss paper and an iron to do toner transfer. I have tried both FeCl3 and H2O2/HCl and in both cases the ground plane gets etched and pitted. I keep a close eye on the board and pull it into a water bath as soon as the traces are etched. Any tips? I have set my printer density as high as it goes and have also tried coloring in larger sections with sharpie after the toner transfer is complete just to add some protection. The transfer itself looks good, no peeling or bubbles.

Thanks for any tips you can offer.

m-Kresol

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Re: General Etching issue
« Reply #1 on: October 22, 2016, 11:44:04 PM »
First, please stay away from the HCl/H2O2 combination. This will give you chlorine gas, which in turn is rather toxic, gives you lung oedema and other nasty business and needs a professional fume hood to work with. It's just not worth the risk.

The issue sounds like one of two possible things.
*) your toner transfer is not fully sticking to the copper. Make sure you ruff the copper up a bit with the scratchy side of a sponge or 600 grit paper to remove any impurities and give the toner something to stick to. Maybe give it 5 extra minutes with the iron just to be sure.
*) concentration of your etchant. What kind are you using? Is it getting hot? The FeCl3 solution is acidic by nature, so if it is too concentrated it might just be too aggressive for your toner. Maybe try to dilute it a bit.
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Geetarded

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Re: General Etching issue
« Reply #2 on: October 23, 2016, 03:03:24 PM »
Thanks for the tips m-Kresol. I have a background in chem and understand that the HCl method is a risk. Only work outside with that stuff and keep your face back kids! My PCB prep method is nearly as you describe. I rough it up, wash with water and dish soap, then rinse and dry without touching it directly again. I hit it with the iron for 10 min going in small circles. The transfer looks like it works well; I think the issue is likely with your point number 2.
HCl/H2O2 is too aggressive for my liking. The FeCl3 solution is homemade by dissolving iron in HCl then oxidizing with H2O2. I wasn't able to add enough iron initially to be in the proper molar proportions due to the size of my container, then got impatient and wanted to try it right away so I dumped in the H2O2. What I may have ended up with is a dilute sol'n of FeCl3 in a relatively concentrated sol'n of HCl/Water. I have some pH strips en-route, so maybe I can do some troubleshooting based on the pH. I am guessing it will still be somewhat ambiguous and I may be better off just throwing some more iron in there and heating it.


m-Kresol

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Re: General Etching issue
« Reply #3 on: October 24, 2016, 01:12:37 AM »
ok, I see. I actually would not even bother making it on your own. you can usually get ready to use FeCl3 solutions for etching at your local electronics shop.
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stringsthings

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Re: General Etching issue
« Reply #4 on: October 25, 2016, 06:34:47 AM »
Make sure you agitate the solution during etching.  This helps to keep fresher etch solution over the copper bits.
I just rock the container back and forth gently.  I also time the etching.  If it's taking longer than usual, the etch solution is spent.
I use HCL/H202 and the average time is 3-4 minutes.  Muriatic acid is easy to find and not too concentrated.  Hydrogen peroxide is even
easier to find.


For ferric chloride, I believe heating the solution is effective.  A warm water bath is easy to do or you could use a double boiler setup.
I've also seen people use an air bubble stream ( like from an aquarium pump ).
« Last Edit: October 25, 2016, 06:37:18 AM by stringsthings »

EBRAddict

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Re: General Etching issue
« Reply #5 on: October 25, 2016, 01:17:25 PM »
This is something you might try: one of the ready-made kits supplies a heat-applied plastic based foil which sticks brilliantly to the heated toner. I'm guessing it is some cheap craft-type iron-on foil. Anyway, it works amazingly well at keeping the ferric chloride away from the large ground planes. I just touch it up with some nail polish if there are any creases after running it through my modded laminator.

Check out "fab-in-a-box". I'm hesitant to leave a recommendation because the instructions suck and I found the person who responded to my help request fairly rude, telling me to read the instructions when the instructions didn't include the information I needed. It might have been a language issue. It works OK as a system but I had to modify some of the steps (like gently brushing away the foil from the copper I wanted gone before the acid wipe down).

Fndr8875

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Re: General Etching issue
« Reply #6 on: December 21, 2016, 12:58:24 PM »
i used adobe acrobat and cut and paste as many transfers as i can fit on a couple pages, put it on thumb drive, then go to office depot and get it printed there. They have the massive laser printers and nice thin gloss paper. Think i paid like 4 bucks and i have about 100 different transfers, prob more like 35 as i never do just 1. But it sucks not being able to just print someting out and do it right then. You can also upload them to there site and when you go your in and out. they also have nice paper trimming deal not sure what its called where you can slide the blade  to cut it. But i only iron for a min or two and it comes out dark traces. also depends on if your using single or double sided pcbs. Another thing i found was go to walmart and get some tin snips, that used to be the worst part of etching for me, dremel or rotary will create so much dust its unbelievable. But they had some 7" ones for like under 5 bucks. The double sided pcb didnt work well , one side would get these cracks along the cut, but i finally just ordered 3 big ass slabs of single sided. Im impatient , but i finally ordered the single sided and it irons on betters, is easier on my pcb drill bits, uses less Fe CL, and its opaque so you can hold up to light and see if all copper is gone. The scotch tl902 from walmart is awesome 20 bucks and gives a super even image, but i burned mine out using dumb radioshack double sided, and have a decent iron, and since it only takes couple min tops to iron on im just doing that for now, will be getting another laminator very  soon.

flanagan0718

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Re: General Etching issue
« Reply #7 on: December 21, 2016, 03:04:06 PM »
Are you cleaning the Copper Clad before you transfer the toner? I usually wet sand the copper clad with some 1200 grit then clean it off with "Goof Off". Then I Iron the toner on. I noticed some of my etches looked pitted or "dulled". That's when I started doing the 10 min of Copper clad prep before ironing. It made a huge difference on my etches.

Fndr8875

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Re: General Etching issue
« Reply #8 on: February 12, 2017, 03:20:09 PM »
Fresh Fe Chl, heat it up for like 10-15 seconds in microwave, then put board in, put top back on plastic tupperware, and shake the hell out of it. Itll give me a perfect etch in like 5 min or less. I think the most important thing is prepping. I use fine steel wool til its super shiny, I thought i was out of Fe Chl but found a small tupperware container last night. It was pretty nasty, really dark and thick, anyway i prepped board like i always do, didnt heat it, barely agitated it other than a few shakes her n there. about 20 min later it was almost done. I took it out, used a sponge to dab the parts it didnt eat away. after rinsing suprisingly results were as good as with fresh. Im curious about sodium persulfate, just because the ferric stuff is just nasty, will stain the shit out of everything, u gotta really pay attention.