Desoldering with Hydrochloric Acid

[king_joolian]

This appears to be the simplest method for removing large numbers of components. Someone more experienced may inform us of any stupidity relating to this idea. Couldn't find any other info relating to doing this, didn't spend hours looking.

Dump your populated boards in a bucket, add 50/50 hydrochloric acid / water to cover the boards.
Sit back and relax, for 3 days, without breathing any fumes. Do this outside.

The solder will be 'one of the first things' to get attacked and may leave a sticky mess all over everything. Possibly causing other problems down the line. This was attempted with old leaded components, not any premium silver based junk.

Pour off and keep the acid, when you can see that the solder blobs have been removed, it should no longer be fizzing at any great rate either.

Wash everything down with hot water and keep all the juices, they may contain something useful, or at the very least be completely toxic and corrosive.

I have only tested this out on SDRAM sticks so far. Chips and other SMD components rubbed right off.

 

[patnor1011]

and tell me what is this your "process" good for?

 

[Lino1406]

What'll you do with the lead chloride formed?

 

[Trigg3r]

Sounds like a expensive way to get lead. After drooping and seeling the lead i belive the Hydrocloric acid will be more expensive than the lead u recover.

 

[butcher]

lead passivates, oxidizes and builds protective layer, so other metals can be disolved faster in same solution, tin from solder can really complicate things, filtering is almost impossible with any quantity of tin, you can settle and decant, but still troublesome to seperate metals wanted from the tin matrix, inceneration and several steps it can be done but, you are setting yourself up for much more work and troubles.

seperating your components may seem time consuming but dissolving solder into your metals is an endless battle to get back the values, keep out the solder as much as possible,
you can recover from it but why make yourself trouble?

 

[Lino1406]

That's right. Tin will cause trouble when using Nitric acid .
Lead (and silver) when using HCl. Until leadless solder
prevails, better not to attack the problem from
that angle, but to minimize by using A/P process

 

[king_joolian]

The whole point of this isnt to collect the lead. It is to collect all the components without having to cut them off.
Certain old components can be much more valuable than the metals they contain.
That is not to say that flatpacks and others are not worth processing for their metal content.

It takes roughly 1-2 cents worth of HCL per motherboard, If there isnt even 2 cents worth of values in components to be harvested from a fully populated motherboard, why does anyone even bother?
Unless youve got a secret method to harvest any precious metals present that doesnt even involve opening the computer??

Is it the lead in the solder dissolving and the tin bubbling onto everything?

Lead is not even remotely on my list of collected metals, it seems like a good idea to be removing it.

Take lead waste to a battery recycling place if you really cant think of what to do with it.

 

[eeTHr]

I had some ram boards, with gold printed circuit traces, that I soaked in muriatic to get the solder and components off. The components and what looked like powdered solder fell to the bottom of the jar.

The reason I did that is because i didn't want the solder in my aqua regia solution, and I figured the components would fall off at the same time, which they did.

I also did this with some power transistors which were solid copper on the bottom, ceramic round tops, with wide flat "pins" coming out from between the ceramic and the bottom. The entire bottom and the tabs were dull gold plated, and there was gold under the ceramic also. The muriatic took the solder off the tabs and also ate whatever was holding the tops on, as a bonus.

In both cases there remained a very thin dull gray where the solder had been, but whatever that was didn't screw up the AR like I think the solder would have.

So I thought it worked great.

Is there something wrong with doing this?

 

[butcher]

tin will disolve in hcl, lead will just break down to lead chloride powder insoluble,tin or lead can collect any values in solution, as long as no gold disolved or is left in the powder at the bottom of your vessel, you should be ok, but that will not always be the case,the dissolved tin in solution is not too much of a problem with just HCl, as long as it is not in high volumes,but when in nitric or if much in aqua regia you'll have troubles, not trying to discourage you but I have done this and spent months seperating the silver tin lead and gold, when a little work seperating them before mechanically would only have taken a small amount of time, I think if you persue this method you will find it a balancing act, with how much lead tin solder is in solution and if oxidizers used whether values are mixed with these,
there are reasons why people try to discourage certain ways of doing things,either we tried and found out the problems, or know of better ways. also you may be able to do something once you learn how to deal with all the troubles that come with it but many starting out will not, and then they loose there values or are constantly asking help for how to get out of the messes they created,with that said my suggestion seperate mechanically as best as possible, eliminate base metals period, or learn or ask how do I get my gold out of this mess, I am not saying it can not be done just since I have done it, am saying there are better ways less trouble and less wasted. good luck if you want to keep doing this, sometimes we have to try and get our own education on these things, but darn I wished I wasn't so hard headed and did not have to always learn the hard ways first. :lol:

 

[eeTHr]

butcher;

First, l want to say that I appreciate your, and everyone's, help on this forum very much.

However, either you are totally misunderstanding king_joolian and me, or I am totally misunderstanding one or both of you two!

Let me try to make this as simple and clear as possible---

I soak boards in HCl, remove the boards and wash, then dissolve the Au in an entirely different solution. I think that's what king_joolian was saying also.

How could this muck up the Au solution? (Which it didn't.) :?:

 

[butcher]

Maybe I am misunderstanding what you are doing here, but trying whole circuit boards in acid complicates things, bsides the organics involved ,gold is fine plated, hcl can disolve base metal underneath, gold and silver can mix with the lead powders at bottom, but can also plate to metals higher in series left, as i said it can be done, but can also complicate things, I have used this for a recovery process, with good results, but also I have seperated the tin, lead, silver, copper, and gold, from each other and this can get very time consuming and it is almost impossible to seperate them completly without loosing some values in each, with the little bit of precious metals involved, and the time consumed the cost of chemicals, and waste materials to deal with I am just saying why? there are better methods.

 

[eeTHr]

butcher;

Like I said, it worked fine for me with a few memory sticks. It prevented the solder from getting into the A/R. I do it with desoldered pin headers, too.

But I'm always ready to learn. What is the better method of removing solder?

And is there a better way of removing components, too?

 

[patnor1011]

this is only my opinion.
i did not heard about any of big guys in factories processing escrap this way. that means the process is more then likely not economical. another thing is that by doing this you are putting itself in situation where you have acid contaminated by various metals which is hard and not easy to separate so you have more waste to deal with when properly disposing. if ram stick is the case, when fingers and chips are cut off, you can toss it into pile and sell to recycler. board soaked in hcl cant be looking good for them to pay for

 

[butcher]

http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=39&t=831

 

[patnor1011]

http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=39&t=831

hehe you are reading my mind. i was getting info from there too as i was looking for something for another member... :lol:

 

[eeTHr]

if ram stick is the case, when fingers and chips are cut off, you can toss it into pile and sell to recycler.

I had some ram boards, with gold printed circuit traces

there are better methods.

I do it with desoldered pin headers, too.

Thanks fellas. I think I'm getting the picture now.

8)

 

[king_joolian]

Could be a pain getting gold out of solution.
I guessed the copper under the gold wasnt getting a chance to dissolve, but on closer inspection there is a tiny bit of gold missing from the ram stick. Although for me, cutting off all those fingers is far worse. Maybe electrolysis could help retrieve that gold. 99.9xx% still remains on the board after HCL treatment though.

eeTHr says "I soak boards in HCl, remove the boards and wash, then dissolve the Au in an entirely different solution."
That is entirely the right idea and works great on everything ive tested so far.
Just dont leave the boards in the HCL for long enough to attack the copper. Boiling HCL also rips through copper, so keep it room temp.
Now you have boards with only the gold, and plastic layer masking the copper tracks.

The toaster oven method in the above mentioned link sounds interesting, but toasting exotic plastics and fire retardants in the back yard, sounds 'not that sensible', when you could be leaving the plastic in place and attacking the solder with HCL.

This has only been tested at bucket in the backyard scale. For commercial operations, im sure the fire breathing mega machine will do the job much cheaper.

patnor1011 says "...if ram stick is the case, when fingers and chips are cut off, you can toss it into pile and sell to recycler. board soaked in hcl cant be looking good for them to pay for "
What do companies that take the depopulated, gold free boards go after?
If it was me, itd predominantly be the copper. Based on that, Im sure they would want some boards that look straight from the factory, free of solder. Its not like the hcl etches swastikas into them.

If anyones still not convinced, demand some photos of why HCL beats the chisel. Or take my worthless n00b word for it and try it out. Its not like you have to spend 10 hours cutting fingers or pins.

Thanks for the input and link to the possible methods.

 

[eeTHr]

king_joolian;

Now you have boards with only the gold, and plastic layer masking the copper tracks.

Although for me, cutting off all those fingers is far worse.

On my ram sticks, I had already cut off the fingers. Then I had soaked the boards in lye, which removed the masking to expose the gold circuit traces. That's when I soaked them in HCl to get rid of the solder and the components.

I guess I could have just left the fingers on, but I did a batch of fingers before I even thought of how I would do the ram stick boards thenselves.

 

[glorycloud]

Gentlemen, do as you please but there is a wealth of information on this forum
and members that are eager to help those that want to be helped. It doesn't take
long for those who are trying to help to spot folks who don't really want to be helped
by following instruction from those with perhaps more experience.

The object is to process your material to most effectively be able to refine your
gold and other precious metals "trapped" on all those computer boards. Processing
material is soooooooooooooooo much different than refining material.

A word to the wise is usually sufficient. 8)

 

[Harold_V]

Processing material is soooooooooooooooo much different than refining material.

Exactly why I am not of much use on this forum. My expertise, if there is any, revolves around refining extracted metals. I have very little experience with e scrap, which appears to be the main focus of this group.

A word to the wise is usually sufficient. 8)

Chuckle!

It is often beyond reason to expect that those that read comments have the key element, which is wisdom. Some folks simply refuse to be educated and will stick by methods that are less than functional, secure in the belief that they know what they're doing and have no need for enlightenment. We have readers like that on this board. You can't tell them a thing to help them, so I no longer try. They don't want to be educated, they tend to seek others that agree with them, and nothing more.

Harold