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Sponge + Ferric Chloride Method -- Etch PCBs in One Minute!

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Step 3: Etch the Board (Instant Gratification!)

Put on your rubber gloves.

Open the bottle of ferric chloride and put the sponge over the opening, and tip the bottle to let about a tablespoon or so of solution saturate into the sponge.

Now with the circuit board in the palm of one hand, simply wipe the solution-saturated sponge over the surface of the board over and over. Don't scrub, just keep wiping it all over. In just a few seconds of wiping, you will see the copper start to disappear!

You will find that unlike the submersion etching method, the copper in the center of the board etches away first, so you might want to try to focus on the edges as you wipe.

In less than a minute of continuous gentle wiping, your board will be fully etched before your eyes!

Drop the etched circuit board into the bowl of water to stop the etching action.

If you are etching multiple boards, you can rinse out the sponge, squeeze out most of the water, then re-apply ferric chloride solution if desired, but I have found that I can etch two 2" x 3" boards with one application.
 
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mjenkins12 years ago
Great instructable Jim!

Those of you having trouble, I can explain. Jim is using 1/2 oz copper laminate. If you're using 1 oz, it takes considerably longer. I like using the 1/2 oz copper boards just for this reason - it goes so much quicker. (I've done it with both types of board.)
Aha! Thats why this didn't work for me like described. I didn't see it disappear before my eyes...I had to scrub and scrub and scrub until I scrubbed away the toner. I didn't pay attention to the oz of the boards I bought...ugh. I'm guessing they are all 1oz because of the way they reacted.

Well, you live and learn. At least I did it! :) I used wax paper and laser printer. Just FYI, that method fattens up your traces. So next time I'm using one of the other proven methods.

Fun stuff though!
Whilst this looks great for most boards, I would not recommend that you use it for boards with permanent marker resist — I just tried, and it wiped some of the marker off! I quickly changed plan and used the tub method.

Regardless, it was my first ever PCB and it's not too bad, I think!
Forget the permanent markers, get a proper 'Dalo Pen' for PCB work instead.

I use mine for touching up toner transfer on the occasion there is a hole or some other problem.
TechShopJim (author)  Barnaby Walters2 years ago

Good point! Yes, Sharpie pen will often rub off, even during traditional tank etching.

I've never tried this, but I wonder if a paint pen would work? It might be a little bit too coarse, though.

There is a so a type of pen called a Rapidograph made by Koh-I-Noor (intro video on YouTube at http://youtu.be/xHSIk4Y79BY) that are really amazing and cool pens for drawing VERY detailed drawings. You fill them yourself with any india ink, so if you used a waterproof india ink, I wonder if that would work for resist for PCBs?
I have heard that 'lacquer applicator' pens work very well as their ink flows better and is a bit gloopier than the thin permanent marker pens. I was using a sharpie, and found that, whilst the thin end was required for the smaller details, I actually got fantastic results with larger traces using the felt end.

The rapidograph looks interesting — I may have to get hold of one of those.

P.S. My PCB soldered very well — on to testing now :|
jeff-o3 years ago
I just used this method to make a board. It was indeed faster than simply dropping it in a vat of ferric chloride, but not quite as fast as it seemed to take for you! Also, I needed to refresh the ferric chloride in my sponge a few times for each side of my board, because it was becoming saturated. Indeed, when I squeezed out the sponge, there was a lot of black and a lot of bright green; indicating the solution was saturated with copper.
shimniok4 years ago
Thanks for this instructable!  Really helped inspire me to make my own boards, something I've been "scared of" for years and years.

Have tried the sponge approach a couple of times on small boards (2x3 or smaller) and am finding that just rubbing with the sponge takes awhile and requires multiple rewetting of the sponge with FeCl to be effective.  Maybe I am doing something wrong?

The last board I did I instead tried soaking my board in pure FeCl for about 30 min, then rubbing with sponge and didn't use any water whatsoever. The rubbing part took much less time with less mess.  Still experimenting...
EdgarX4 years ago
I think it's good the method, but we need to deposite all the copperremoved when you clean it in a place safe for avoid to pollute the enviroment.
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