Interesting Etching Method

[irmcdermott]

So, in my effort to save money, and save etchant, i just tried a different etching method that I found here:
http://www.instructables.com/id/Sponge-Ferric-Chloride-Method-Etch-Circuit-Bo/

After giving it a shot, here were my results on the Faultline board I just etched:



Thoughts:
- It took WAY longer than "one minute" like the title suggests. Maybe 15-20, but it was my first try, so I may not have had enough on my sponge.
- I did have to reapply the sponge with some etchant 2-3 times, but again, maybe I didn't have enough on there to start.
- Not sure I'm comfortable with just rinsing out the sponge down my sink. Usually with my used etchant I keep it in plastic bottles... haven't figured out where in my town I can take it.
- I'm happy with the results (only see one or to spots I may need to fix) and I like the idea of only using what I need, making my etchant go a lot farther than it is right now.

Ian

[madbean]

FYI: with a 1:1 mix in a plastic bin, a 4x6" piece of 1oz PCB will etch in about 5-6 minutes. A 1/2oz board will etch in about 3 min. You can add additional peroxide to re-activate the solution, too.

[stecykmi]

looks like a good quality etch (except for the small blemish in the bottom right edge). perhaps it took longer because you're using thicker copper clad board?

[irmcdermott]

FYI: with a 1:1 mix in a plastic bin, a 4x6" piece of 1oz PCB will etch in about 5-6 minutes. A 1/2oz board will etch in about 3 min. You can add additional peroxide to re-activate the solution, too.

Sorry, a 1:1 mix of what? right now i'm just using radio shacks copper etchant.

[madbean]

Oh, my bad. You are using FeCl as your enchant. I was talking about Muriatic Acid and Hydrogen Peroxide. You can buy the acid at Lowes for $6 and the Peroxide anywhere for $1. It lasts a long time. Cheaper and less environmental impact. Plus, much less nasty. However, you need to use a mask when you mix it. The acid is very potent. It's not too dangerous, though. It causes mild irritation to the skin.

[irmcdermott]

Definitely going to try that. I've never been a fan of FeCl, but it's all that i've used. I found an instructables tutorial on this method. so you suggest a 1:1 ratio? I saw somewhere else that suggested 2 parts H202 to 1 part HCl

[madbean]

1:1 is the way to go. You don't need that much peroxide to activate the solution.

[stecykmi]

Definitely going to try that. I've never been a fan of FeCl, but it's all that i've used. I found an instructables tutorial on this method. so you suggest a 1:1 ratio? I saw somewhere else that suggested 2 parts H202 to 1 part HCl

i use the hydrogen peroxide, hydrochloric acid method. the actual etching has worked fine for me, but I for some reason that I've yet to determine, the solution looses ALL potency after sitting for a while. I've done two big batches of various PCBs, and each time I'm forced to make a new batch of etchant. I suspect something is evaporating (possibly the chlorine), but I'm not a good enough chemist to figure it out for sure...

[irmcdermott]

from what i've read, and based on what madbean said, it seems that you need to add more oxygen (in our case the hydrogen peroxide, or H2O2).

This page does a good job explaining what is going on chemically in this etchant:

http://www.instructables.com/id/Stop-using-Ferric-Chloride-etchant!--A-better-etc/step4/Chemistry-Break/

[irmcdermott]

also, i just etched another Faultline board, this time with the HCl/H2O2 solution.... it did great and was super fast... unfortunately, i guess my transfer wasn't the greatest, and my Sharpie didn't do a great job when I was touching up the board before putting it in the etchant. i'll be giving it another shot tomorrow. very excited about the longevity of this etchant. thanks again!

[madbean]

You can re-activate it with more peroxide as you are etching. Once it turns dark usually a splash or two will turn it green again. It can be re-used, but in my experience it is much weaker the second or third time around.

For disposal, I keep a 5-gallon drum I bought from Lowes to store the used etchant. This can be taken to a chemical dump. In Austin, you could dispose up to 5 gallons for free. I actually only have to do this about once a year. The stuff goes a long way!

[irmcdermott]

You can re-activate it with more peroxide as you are etching. Once it turns dark usually a splash or two will turn it green again. It can be re-used, but in my experience it is much weaker the second or third time around.

For disposal, I keep a 5-gallon drum I bought from Lowes to store the used etchant. This can be taken to a chemical dump. In Austin, you could dispose up to 5 gallons for free. I actually only have to do this about once a year. The stuff goes a long way!

So are you saying that you mix a new batch every times you etch a series of boards?

Tonight I re-used the batch I had last night, and I added more peroxide to it, but it took a couple of hours to completely etch. Thoughts?

[Haberdasher]

Rather than start a new thread I thought I'd ask about paper here.

I've read that a lot of people use the Staples brand 'photo basic' paper to transfer the toner to the board, although I'm not sure what would make it better than other papers.  Presumably because it breaks down easily  in the water afterwards..

Any other brand names/suggestions to use for this application?

[madbean]

You cannot get that type of paper anymore, unfortunately. They changed the thickness and bonding on it a while back, and the new stuff just doesn't work. There's a thread on diystompboxes about it.

Other things you can use: PNP Blue, magazine paper, transparency.

I'm currently testing out another type for transfers that is relatively cheap (about 3 cents a page). I'll post more details in the forthcoming tutorial.

[Haberdasher]

Excellent Brian, thanks.

This might be a dumb question, but why is it that everywhere I see artwork for a board there are always two images?  What is the second image for?