Ram only gold plated on unpopulated side ?

[kernels]

Hello from rainy New Zealand guys . . . Was hoping for a bit more advice . . .

I've been taking a second look at the ram modules left over from my gold-plated-fingers harvest. This particular module is only populated on one side of the board and the un-populated side has the pads gold plated. Like this pic showing both sides of the same module:



So, after turning to Hoke for some advice, I decided to boil a piece of the board in some Hydrochloric acid to remove the left-over solder. All good so far.

I left the board boiling for a bit, keeping an eye on the gold plated side to make sure there was no effect from the boiling acid. After a while I removed the board and wiped the black residue from the pads. The result is that I have ended up with one side that is still gold plated and looking good and the other side appears to be just copper ? This is surprising since I would have expected the entire board to be gold plated before any components were fitted.

Any advice ? Am I doing something wrong or is it just that only the 'left over' pads were somehow plated ?

Pics of the two sides post acid are below:

 

[kernels]

 

[kernels]

 

[nickvc]

It's possible the black residue you wiped off was the gold.

 

[kernels]

It's possible the black residue you wiped off was the gold.

This is an excellent question, not sure why the gold would dissolve with the solder though, but seems like a logical train of thought.

Can anyone tell me whether boiling hydrochloric acid has any reaction with gold ?

 

[nickvc]

In chemistry we are taught gold is inert in HCl, this is true until you add an oxidiser and if you leave it open to absorb oxygen, AP, it will start to dissolve base metals and a little gold until it has enough base metals to cement the gold back out, possibly the black powder you wiped off.
Incinerate the wipe and dissolve in AR or whatever method you prefer and test with stannous and you will get your answer as to whether that was gold or not.

 

[patnor1011]

What Nick said.
That gold plating is flash plating and solder simply kind of dissolve it and mix with it so gold end up mixed up in blob of solder. Then you boil it in acid and you will get it as tiny amount of dark/black powder. So you perhaps did not dissolved gold but there is so little it goes off as powder and that powder is so dirty it appears dark/black. Not really worth chasing after, acids and energy used will cost you more than you will be able to recover.

 

[kernels]

What Nick said.
That gold plating is flash plating and solder simply kind of dissolve it and mix with it so gold end up mixed up in blob of solder. Then you boil it in acid and you will get it as tiny amount of dark/black powder. So you perhaps did not dissolved gold but there is so little it goes off as powder and that powder is so dirty it appears dark/black. Not really worth chasing after, acids and energy used will cost you more than you will be able to recover.

Thank you Patnor, sounds like you are on the money here. My real objective was to remove the solder so that I could process the boards with my regular AP solution without the possible added complexity of lead / tin in the mix. Is there a better way to prepare these boards for processing ?

 

[nickvc]

Throw the wipe in with your old filters, it's your gold at the end of the day.

 

[patnor1011]

Some people here remove green mask and try to recover tiny bit of plating sometimes present on some areas under green mask. I am not believer. While there is indeed gold present on some boards it is so little it would not warrant to bear cost associated with doing so. Perhaps I may be inclined if it would be some ancient board or military one but certainly not RAM stick. I am also not on friendly terms with hot lye bath and I try to avoid potential dangerous situation as much as I can. I believe that there is a beauty in simple things.

Put them in AP as they are or use cyanide based leach. There is one available and while I do not have personal experience with it yet I am in contact with person who does use it and do have interesting results. I plan to test it on various samples even RAM like you do have but even that I am ready to go with all reagents, chemicals and samples ready I do have to wait due to my recent health complications. Stay tuned I will post as much results as I can in the next 3-4 weeks.

 

[Anonymous]

I think people need to be very careful bandying figures like 1g per Kg around in all fairness because then it becomes expected. The range is frankly enormous.

 

[nickvc]

Jon I'm with you on that point, some may only get 1/2 a gram others 1/3 of a gram, in some cases it pays to sell as is and let others worry about the yield, very few home refiners will ever get all the values because of the many processes needed to recover them and the loses incurred can outway what you would get paid for them as is, the same as cats why refine them when you can sell them for more than you can recover.

 

[kernels]

Hi guys, maybe there has been some miscommunication, I'm not trying to remove the solder mask, have never found there to be anything other than copper under the solder mask of cheap-ish boards. I'm only trying to get rid of solder so that the boards can just be processed with the rest of the fingers in AP without the complications of lead and tin.

I can't seem to find a tutorial or thread that covers what to do with boards once you have removed the components to strip the lead and tin selectively. Was hoping the boiling in HCl would do it, but that appears to have some other pitfalls ! Do you guys just AP the boards with solder still on ?

 

[patnor1011]

Yes.

 

[Barren Realms 007]

Hi guys, maybe there has been some miscommunication, I'm not trying to remove the solder mask, have never found there to be anything other than copper under the solder mask of cheap-ish boards. I'm only trying to get rid of solder so that the boards can just be processed with the rest of the fingers in AP without the complications of lead and tin.

I can't seem to find a tutorial or thread that covers what to do with boards once you have removed the components to strip the lead and tin selectively. Was hoping the boiling in HCl would do it, but that appears to have some other pitfalls ! Do you guys just AP the boards with solder still on ?

You might not have run into it but you need to be aware that under the solder mask of some older gold fingered smaller RAM sticks there is gold plating.

 

[kernels]

Yes.

Billiant Thanks, that is what I was hoping. Will still run them separate from 'clean' items like fingers, but that will definitely make my life easier.

 

[kernels]

Hi guys, maybe there has been some miscommunication, I'm not trying to remove the solder mask, have never found there to be anything other than copper under the solder mask of cheap-ish boards. I'm only trying to get rid of solder so that the boards can just be processed with the rest of the fingers in AP without the complications of lead and tin.

I can't seem to find a tutorial or thread that covers what to do with boards once you have removed the components to strip the lead and tin selectively. Was hoping the boiling in HCl would do it, but that appears to have some other pitfalls ! Do you guys just AP the boards with solder still on ?

You might not have run into it but you need to be aware that under the solder mask of some older gold fingered smaller RAM sticks there is gold plating.

Thanks, will definitely check them out.

 

[g_axelsson]

What Patnor said!

Molten solder dissolves gold quite easily. The thin gold flash is only there as a protection against oxidation so the cards will be easy to solder. When the solder is dissolved (via HCl or in copper chloride) the gold will form a fine mud (probably black) that settles on the bottom after some time.

And a bit off topic, some boards that actually are worth going after the plating under the solder mask is boards from HP equipment from the 1970-1985 era. They made some beautiful boards with fully gold plated wires and solder mask only on one side. If you have seen one you will know what I'm talking about. They don't make them like that any longer.

Göran

 

[kernels]

What Patnor said!

Molten solder dissolves gold quite easily. The thin gold flash is only there as a protection against oxidation so the cards will be easy to solder. When the solder is dissolved (via HCl or in copper chloride) the gold will form a fine mud (probably black) that settles on the bottom after some time.

And a bit off topic, some boards that actually are worth going after the plating under the solder mask is boards from HP equipment from the 1970-1985 era. They made some beautiful boards with fully gold plated wires and solder mask only on one side. If you have seen one you will know what I'm talking about. They don't make them like that any longer.

Göran

Great, thank you for the advie When you just get started with this game the amount of things that are not as you would expect is huge!

 

[modtheworld44]

I think people need to be very careful bandying figures like 1g per Kg around in all fairness because then it becomes expected. The range is frankly enormous.

spaceships

I agree that bandying figures around is not a good practice,it gives false hope to newbies and other members alike that have not done a big enough batch to get a true result.I run a 21 pound batch of the fully depopulated ram sticks about 3 years ago and only got 0.2grams from it.This was about a year after I had started my own yield data base.



modtheworld44