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copper chloride stooped mid etch!

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tracidfish

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Okay so I have been ethcing using copper chloride but now it has stopped etching mid way through an etch.

i have heard it is possible to regenerate it but havent found out how.

What can i do?

is the surrent board in the etch tank ruined?
 
Reading your threads you've been making your own etchant, I've made boards with ferric chloride, and if you wash off the board thoroughly and kept dry and out of light you'll should be able to keep it for a day or more and continue etching.
The thing that can go wrong is the etch resist, and seeing as you've made you r own etchant that might happen.
 
What is the concentration of copper chloride? How much free acid is there (approximately)? Are you generating the copper chloride in situ using hydrogen peroxide and HCl?

With fresh etchant and under reasonable conditions, it is hard to imagine that the etchant became exhausted with just one board. I suspect it is something else.

Can you post a picture of your etchant that stopped working against a white background. A drop or two on clear glass with white background would be even more informative. Can you show the board?

Is your resist toner or a photosensitive resist? Positive or negative acting? If your developer is alkaline (e.g., sodium hydroxide, sodium carbonate, etc.), then your partially etched boards should be stable once washed. No need for darkness, but I would't lay them in bright sunlight.

As for regenerating the etchant, the easiest way is to just bubble air through it. Hydrogen peroxide will do the same a bit quicker, but you may want to use a more concentrated, such as 30% or more as mentioned before.

John
 
What is the concentration of copper chloride? How much free acid is there (approximately)? Are you generating the copper chloride in situ using hydrogen peroxide and HCl?

With fresh etchant and under reasonable conditions, it is hard to imagine that the etchant became exhausted with just one board. I suspect it is something else.

Can you post a picture of your etchant that stopped working against a white background. A drop or two on clear glass with white background would be even more informative. Can you show the board?

Is your resist toner or a photosensitive resist? Positive or negative acting? If your developer is alkaline (e.g., sodium hydroxide, sodium carbonate, etc.), then your partially etched boards should be stable once washed. No need for darkness, but I would't lay them in bright sunlight.

As for regenerating the etchant, the easiest way is to just bubble air through it. Hydrogen peroxide will do the same a bit quicker, but you may want to use a more concentrated, such as 30% or more as mentioned before.

John

Hi There

Thanks for your help. Im sorry if i cant answear all your questions correctly as i am new to this but here goes;

I started with
600 ml hydrochloric acid (28%)
400 ml hydrocgen peroxide (9%)

I am using posotive photosensitised resist. The developer is sodium hydroxide 10grams in 1L. The board developed
niclye showing sharp dark lines where they should be.

I have done some test boards. Though i did not get the "fizz" i was expecting after wathing videos on you tube. I did get some fizz but not as much as i was expecting.

I cannot get any pictures at the moment. The etchant is green though not hugley dark green.

I think i have made a few mistakes that i can see.
Firstly I poured all of the solution I made into my etching tray. i think I may have been better just using what I needed.
Secondly i made the solution using all of the peroxide I had in stock. this has left me little room for regeneration.
Thirdly I did some test strips to get comfortable witht the process.. probably used 2 160x200mm cards. Maybe this has exhausted the ethcant.

How long does it take to regenerate using air?
I have seen ething tanks with air diffusers in, i think making one of those will be my next task.

Thanks again
your help is appreciated.
 
Based on those proportions, that mixture has plenty of HCl.

Let's start with the peroxide. There are some confusing ways to describe its concentration. For example, peroxide that is used in cosmetic shops to lighten hair has a rating system that makes it sound quite potent, but it is really quite weak.

Where did you get the peroxide?

When the solution is active, it is bright green. If the solution appears olive drab or has any brownish character to it, it is not completely oxidized to cupric(II) chloride. A small drop against a wjite background will show the brown. Have you seen Seychell's how to do it? Unfortunately, Chrome gives a warning for the site now. This picture is from that description. The upper left dot is fresh cupric(II) chloride. Copper(I) is not active. So the more copper(I) the more exhausted the etchant is.

untitled.png

Do you have any bare copper, like from electrical wiring? Try putting some of that in your solution.

As for air regeneration, that is what I use, and I just go by color. Overnight bubbling will probably work. I have never timed it. At this point, however, I suspect you have very little cupric chloride and will need to depend on the peroxide to get etching. That is why I suggested starting with figuring out the type of peroxide you had.

John
 
Thanks once again.

My peroxide is from a pharmacy, used for mouth wash and skin disinfectant.

It says it is 9 % but there is a 30 Vols beneath it, i do not know what this means.

The colour is of the 2nd one so 0.5 mg/l? Do you have a link to Seychell's?

I will find some bare copper to try.

When you say I may have little cupric chloride can you explain this to me? Is the cupric chloride what has turned the liquid green?
 
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It says it is 9 % but there is a 30 Vols beneath it, i do not know what this means.

The first is probably the correct, as a chemist, way to express the percentage. The vols% represents the volume of oxygen produced by one unit volume (e.g., 1 mL) of the liquid. It can be converted to weight percentage of peroxide easily, but that is not important here (22.4Lof gas = 1 mole = 32g of oxygen) . It illustrates what I meant by the misleading percentage used for peroxide used to bleach hair.

As for bare copper, you must have some electrical wire as is used in a house. It won't take much. Just remove the insulation and put the wire in your etching bath. Remember that your PCB is probably 0.5 or 1.0 oz of copper per foot^2. One ounce (30 g) of copper wire will suffice to make an etching bath.

Remember, peroxide plus HCl will etch too, and many people use just that. The problem, if it is one, is that one never knows the concentration of peroxide present, because peroxide can simply decompose to water and oxygen. I use copper(II) chloride (cupric chloride) like you are trying to do. In that case, you know or have a pretty good idea of the concentration of cupric ion that is present.

Here s the link for Adam Seychell's article: **broken link removed**
Chrome gives a warning, but it may be a little too sensitive.

John
 
Thanks.

I have put the copper wire in as you suggested. It appears to have turned a slightly lighter colour.

So would you suggest that i nay have needed more hydroxide to start with?
 
It is not a good idea to work with two user ID's on this site. Are you tracidfish?

Maybe a moderator can fix that issue.

John
 
How dark green is your solution? Mine, which I made from cupric oxide + HCl, is a deep emerald green and etches quite well. I am sure something less concentrated will work too, but as mentioned, if it is pale green, you may need more peroxide to keep it going. Also, if you put your etch tank in a bowl of hot water (<=60 C) the etch speed will increase considerably.

John
 
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