# Here is the answer to solder removal.



## DNIndustry (Feb 26, 2010)

I think that the 4th most asked question on the board has been how to remove solder. 
Here ya go.

1 Part Acetic Acid + 1 Part 30% H2O2

Slow to start and no heat is required.
Do it in a ventalated area.
After a couple of hours it got really vigorous...seriously. Could have been the Iron in the pin that catalized the h2o2. I dont believe additions of peroxide are really necessary. 
Check on it after a few hours. they should be all done
Mine mechanically removed the lid to some pentiums so it saved time, but to show off it ate through the ceramic style lids....


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## Oz (Feb 26, 2010)

Well if vinegar can do that, especially without the 30% H2O2 you are really on to something. I would love to hear greater details.


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## hemicuda (Feb 26, 2010)

Yes this does sound very interesting, I will be looking forward to hearing more on this topic as well!! :shock:


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## DNIndustry (Feb 26, 2010)

What I meant by additions of H2O2 was after the initial mix. I dont believe periodic h202 injection is necessary like with AP, but I guess that would be relative to how much solder you are removing.
Just enough to submerge the item with a 1/4 inch of liquid above it is sufficient


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## Irons (Feb 26, 2010)

DNIndustry said:


> What I meant by additions of H2O2 was after the initial mix. I dont believe periodic h202 injection is necessary like with AP, but I guess that would be relative to how much solder you are removing.
> Just enough to submerge the item with a 1/4 inch of liquid above it is sufficient



Add a little Sulfuric as a catalyst, if you're making it up in advance.

Peracetic Acid:

http://en.wikipedia.org/wiki/Peracetic_acid


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## shyknee (Mar 12, 2010)

quick question? what % was the acid or was it straight Glacial Acetic acid ?
one more question did the mix turn blue ? as in copper dissolving as well ?
i have to try this on some heavily soldered stuff


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## Scott2357 (Mar 12, 2010)

Just as an experiment I used straight 32% HCL. Gets the solder but leaves the copper alone *IF* you keep the oxygen out as I found out in this thread http://goldrefiningforum.com/phpBB3/viewtopic.php?f=37&t=6471&p=57294#p57294 Oxygen is absorbed through contact with the air and a green copper chloride monster is born which will devour all your nice pink copper along with the solder. Use Sodium Sulfite to use up the oxygen and copper is preserved. This in combo with removing the solder mask seems to be a practical way to harvest copper without the troublesome tin/lead getting in the way. Still tweeking the process to get a predictable recipe. Hoping to find a way to sell the seperated solder as well. Will post results when I get more info.


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## Irons (Mar 13, 2010)

Scott2357 said:


> Just as an experiment I used straight 32% HCL. Gets the solder but leaves the copper alone *IF* you keep the oxygen out as I found out in this thread http://goldrefiningforum.com/phpBB3/viewtopic.php?f=37&t=6471&p=57294#p57294 Oxygen is absorbed through contact with the air and a green copper chloride monster is born which will devour all your nice pink copper along with the solder. Use Sodium Sulfite to use up the oxygen and copper is preserved. This in combo with removing the solder mask seems to be a practical way to harvest copper without the troublesome tin/lead getting in the way. Still tweeking the process to get a predictable recipe. Hoping to find a way to sell the seperated solder as well. Will post results when I get more info.



Poor man's HBr. :mrgreen:


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## Scott2357 (Mar 13, 2010)

Isn't it common to nickel plate the copper before solder is applied? If present, that will have to be seperated from solder as well, or just sell it with the understanding there are unknown percentages of nickel in it.


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## shyknee (Mar 14, 2010)

glacial acetic or 5% ?
DNI any pictures available of results


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## leavemealone (Mar 14, 2010)

> Isn't it common to nickel plate the copper before solder is applied?


Yes that is very common.I don't believe samtek offers any pins that are not nickle plated first.I am not sure about Amphenol but Im sure they are the same.
Johnny


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## Buzz (Mar 14, 2010)

From a disposal point of view, what are we likely to be left with when using Acetic acid and H2O2 on
the solder?

Anything nasty?

Regards
Buzz


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## qst42know (Mar 14, 2010)

http://tinyurl.com/7ed5b


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## DNIndustry (Mar 15, 2010)

Sorry about the delay. I just realized I havent checked this post in a while. I will try and answer your questions a little later tonight.


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## gmiller (Dec 2, 2010)

What gases are given off by this process? Should I be doing this under a fume hood and should the gases be scrubbed prior to being released into the atmosphere? 

It works great on fingers. Lots of little foils floating after several days in near freezing temps. outside. I just placed the closely trimmed fingers in a coffee pot, added the solution and put a clear glass plate on top to keep the rain/snow from diluting my solution and after several days sitting outside in near freezing temps. I have lots of floating gold foils, light green solution and clean fiberglass pieces that used to be "fingers".

If the gases aren't too bad this could be a really viable alternative to several of the other formulas embraced by the forum members.

Later, 

Gary


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## Yggdrasil (Apr 1, 2016)

This seems to be one of the topics that is everlasting 

I have been trying different ways of removing solder from PCBs in minute batches.
Amongs others straight HCL, Acetic acid 35% and Sodium Hydroxide.
With Straight HCL the first trial resulted in dissolved copper due to oxygen uptake in the solution.
Second time I decided to try blocking access to the air by adding a lid of food grade vegetable oil.
This had been sitting for a couple of weeks with no apparent action, solder seemed untouched, but suddenly I noticed floating gold specs.
The color was a very light green. And then I checked the forum again, and lo and behold, HCl do dissolve nickel by itself. :-(
Then the "funny" part happened. 
I by accident added the temeparature sensor from my magnetic stirrer into the solution while heating to 40 centigrade.
I had something else to do and forgot the whole thing over night. 
In the morning the temperature probe had dissolved completely in the barrier zone between the HCl and the oil. The color now was dark emerald green.
So now I have to do some tests with emusified oil in HCl just to see what happens, but it is a messy business. ;-)

Sodium Hydroxide gave no tangible result even at 70 centigrade and added H2O2 (Just a splash of 10%) NaOH was made from powdered caustic with no concentration control

I did 2 trials with Acetic acid and H2O2.(35% acetic and a splash of 10% H2O2)
First batch was running for some days with a air bubbler and gave no result, I then added Hydrogen Peroxide. The next day the solution had a beautiful pink/orange color, solder still intact though. Now a week or so later the solder seems to have dissapeared. I'm curious of which meatal is responsible for the color.
The second batch gave a completely different result. Now the color just kept at a pale bluish green untill it evaporated completely.


Do anyone have an explanation of the different results in the acetic batches?

Regards Per-Ove


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## jungle_Dave (Jun 21, 2016)

I've been using peracetic acid with varying results.
If it's hard to get hcl like where I live or you have cheap concentrated vinagar
Peracetic acid is etty well which is a cheap but slow alternative for me
It will also remove tin and lead which becomes lead acetate. 
I recently put a 200 gram batch of mixed pins in 12% vinagar with equal volume of H2O2 at 12%. Added 40 grams of table salt and about 10 ml of 2% H2SO4. I let that go for a week. The solution went from green to blue to yellow. I did strip the solder but not all the foils so I filtered or tryed to filter and made a new batch. Round 2 stripped the foils from the pins for 80% or better after a month.. I forgot about it. but I'm left with a white goo that passes through 3 filters. What's also interesting is that I have no foils in my filter. So what's the goo and where's the gold?

Trimmed ram fingers worked great as did my depopulated phone boards. Took longer then AP but at a fraction of the cost! 
The lead acetate aspect bothers me as its soluble in water.. my attempt to convert it to sulfate failed.


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## kernels (Jun 21, 2016)

Whenever you have a solution of something and you are missing gold, the next thought should be Stannous Chloride. If HCl or Tin is impossible to come by then that makes things substantially harder.


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## jungle_Dave (Jun 21, 2016)

Sorry for the double post..
I know silver can be an acetate as can lead but the white precipitation can be neither. There is no way gold can go into acetic solution nor Pd or Pt?


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## patnor1011 (Jun 22, 2016)

Perhaps you did use too much and too strong H2O2. It is a strong oxidizer and that may be the case that it help to dissolve your gold?


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## jungle_Dave (Jun 22, 2016)

I did add another 40 ml of 12% H2O2 on day 3 as the reaction died down. That's also when it turned yellow. Got to test it!


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## jungle_Dave (Jun 23, 2016)

patnor1011 said:


> Perhaps you did use too much and too strong H2O2. It is a strong oxidizer and that may be the case that it help to dissolve your gold?


Spot on!
Just to test I did a crude experiment.
Added 10 ml of 2% H2SO4 to the first filtrate,agitated and let settle 24 hours.
I have a spiderweb matrix of inpure metailc gold on the bottom of the flask.

I oxidized the gold into solution or micro particulated
How cool is that!

Back to the original post. ..
I used an excess of H2O2 at 12% and it oxidized gold.
30 % H2O2 would for sure.
That's a risk.
I'm waiting on new sncl but I'm saving everything filtrate solution and control sample.


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